Mercurial > hg > graal-jvmci-8
annotate src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp @ 23515:ecbeafff096f
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| author | asaha |
|---|---|
| date | Fri, 18 Sep 2015 08:41:04 -0700 |
| parents | 1bfa56af8869 1f646daf0d67 |
| children | b5f3a471e646 626f594dffa6 |
| rev | line source |
|---|---|
| 0 | 1 /* |
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2 * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved. |
| 0 | 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 4 * | |
| 5 * This code is free software; you can redistribute it and/or modify it | |
| 6 * under the terms of the GNU General Public License version 2 only, as | |
| 7 * published by the Free Software Foundation. | |
| 8 * | |
| 9 * This code is distributed in the hope that it will be useful, but WITHOUT | |
| 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 12 * version 2 for more details (a copy is included in the LICENSE file that | |
| 13 * accompanied this code). | |
| 14 * | |
| 15 * You should have received a copy of the GNU General Public License version | |
| 16 * 2 along with this work; if not, write to the Free Software Foundation, | |
| 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
| 18 * | |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
| 0 | 22 * |
| 23 */ | |
| 24 | |
| 1972 | 25 #include "precompiled.hpp" |
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26 #include "classfile/classLoaderData.hpp" |
| 1972 | 27 #include "classfile/symbolTable.hpp" |
| 28 #include "classfile/systemDictionary.hpp" | |
| 29 #include "code/codeCache.hpp" | |
| 30 #include "gc_implementation/concurrentMarkSweep/cmsAdaptiveSizePolicy.hpp" | |
| 31 #include "gc_implementation/concurrentMarkSweep/cmsCollectorPolicy.hpp" | |
| 32 #include "gc_implementation/concurrentMarkSweep/cmsGCAdaptivePolicyCounters.hpp" | |
| 33 #include "gc_implementation/concurrentMarkSweep/cmsOopClosures.inline.hpp" | |
| 34 #include "gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.hpp" | |
| 35 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.inline.hpp" | |
| 36 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp" | |
| 37 #include "gc_implementation/concurrentMarkSweep/vmCMSOperations.hpp" | |
| 38 #include "gc_implementation/parNew/parNewGeneration.hpp" | |
| 39 #include "gc_implementation/shared/collectorCounters.hpp" | |
| 10405 | 40 #include "gc_implementation/shared/gcTimer.hpp" |
| 41 #include "gc_implementation/shared/gcTrace.hpp" | |
| 42 #include "gc_implementation/shared/gcTraceTime.hpp" | |
| 1972 | 43 #include "gc_implementation/shared/isGCActiveMark.hpp" |
| 44 #include "gc_interface/collectedHeap.inline.hpp" | |
| 10405 | 45 #include "memory/allocation.hpp" |
| 1972 | 46 #include "memory/cardTableRS.hpp" |
| 47 #include "memory/collectorPolicy.hpp" | |
| 48 #include "memory/gcLocker.inline.hpp" | |
| 49 #include "memory/genCollectedHeap.hpp" | |
| 50 #include "memory/genMarkSweep.hpp" | |
| 51 #include "memory/genOopClosures.inline.hpp" | |
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52 #include "memory/iterator.inline.hpp" |
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53 #include "memory/padded.hpp" |
| 1972 | 54 #include "memory/referencePolicy.hpp" |
| 55 #include "memory/resourceArea.hpp" | |
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56 #include "memory/tenuredGeneration.hpp" |
| 1972 | 57 #include "oops/oop.inline.hpp" |
| 58 #include "prims/jvmtiExport.hpp" | |
| 59 #include "runtime/globals_extension.hpp" | |
| 60 #include "runtime/handles.inline.hpp" | |
| 61 #include "runtime/java.hpp" | |
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62 #include "runtime/orderAccess.inline.hpp" |
| 1972 | 63 #include "runtime/vmThread.hpp" |
| 64 #include "services/memoryService.hpp" | |
| 65 #include "services/runtimeService.hpp" | |
| 0 | 66 |
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67 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC |
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68 |
| 0 | 69 // statics |
| 70 CMSCollector* ConcurrentMarkSweepGeneration::_collector = NULL; | |
| 10405 | 71 bool CMSCollector::_full_gc_requested = false; |
| 72 GCCause::Cause CMSCollector::_full_gc_cause = GCCause::_no_gc; | |
| 0 | 73 |
| 74 ////////////////////////////////////////////////////////////////// | |
| 75 // In support of CMS/VM thread synchronization | |
| 76 ////////////////////////////////////////////////////////////////// | |
| 77 // We split use of the CGC_lock into 2 "levels". | |
| 78 // The low-level locking is of the usual CGC_lock monitor. We introduce | |
| 79 // a higher level "token" (hereafter "CMS token") built on top of the | |
| 80 // low level monitor (hereafter "CGC lock"). | |
| 81 // The token-passing protocol gives priority to the VM thread. The | |
| 82 // CMS-lock doesn't provide any fairness guarantees, but clients | |
| 83 // should ensure that it is only held for very short, bounded | |
| 84 // durations. | |
| 85 // | |
| 86 // When either of the CMS thread or the VM thread is involved in | |
| 87 // collection operations during which it does not want the other | |
| 88 // thread to interfere, it obtains the CMS token. | |
| 89 // | |
| 90 // If either thread tries to get the token while the other has | |
| 91 // it, that thread waits. However, if the VM thread and CMS thread | |
| 92 // both want the token, then the VM thread gets priority while the | |
| 93 // CMS thread waits. This ensures, for instance, that the "concurrent" | |
| 94 // phases of the CMS thread's work do not block out the VM thread | |
| 95 // for long periods of time as the CMS thread continues to hog | |
| 96 // the token. (See bug 4616232). | |
| 97 // | |
| 98 // The baton-passing functions are, however, controlled by the | |
| 99 // flags _foregroundGCShouldWait and _foregroundGCIsActive, | |
| 100 // and here the low-level CMS lock, not the high level token, | |
| 101 // ensures mutual exclusion. | |
| 102 // | |
| 103 // Two important conditions that we have to satisfy: | |
| 104 // 1. if a thread does a low-level wait on the CMS lock, then it | |
| 105 // relinquishes the CMS token if it were holding that token | |
| 106 // when it acquired the low-level CMS lock. | |
| 107 // 2. any low-level notifications on the low-level lock | |
| 108 // should only be sent when a thread has relinquished the token. | |
| 109 // | |
| 110 // In the absence of either property, we'd have potential deadlock. | |
| 111 // | |
| 112 // We protect each of the CMS (concurrent and sequential) phases | |
| 113 // with the CMS _token_, not the CMS _lock_. | |
| 114 // | |
| 115 // The only code protected by CMS lock is the token acquisition code | |
| 116 // itself, see ConcurrentMarkSweepThread::[de]synchronize(), and the | |
| 117 // baton-passing code. | |
| 118 // | |
| 119 // Unfortunately, i couldn't come up with a good abstraction to factor and | |
| 120 // hide the naked CGC_lock manipulation in the baton-passing code | |
| 121 // further below. That's something we should try to do. Also, the proof | |
| 122 // of correctness of this 2-level locking scheme is far from obvious, | |
| 123 // and potentially quite slippery. We have an uneasy supsicion, for instance, | |
| 124 // that there may be a theoretical possibility of delay/starvation in the | |
| 125 // low-level lock/wait/notify scheme used for the baton-passing because of | |
| 126 // potential intereference with the priority scheme embodied in the | |
| 127 // CMS-token-passing protocol. See related comments at a CGC_lock->wait() | |
| 128 // invocation further below and marked with "XXX 20011219YSR". | |
| 129 // Indeed, as we note elsewhere, this may become yet more slippery | |
| 130 // in the presence of multiple CMS and/or multiple VM threads. XXX | |
| 131 | |
| 132 class CMSTokenSync: public StackObj { | |
| 133 private: | |
| 134 bool _is_cms_thread; | |
| 135 public: | |
| 136 CMSTokenSync(bool is_cms_thread): | |
| 137 _is_cms_thread(is_cms_thread) { | |
| 138 assert(is_cms_thread == Thread::current()->is_ConcurrentGC_thread(), | |
| 139 "Incorrect argument to constructor"); | |
| 140 ConcurrentMarkSweepThread::synchronize(_is_cms_thread); | |
| 141 } | |
| 142 | |
| 143 ~CMSTokenSync() { | |
| 144 assert(_is_cms_thread ? | |
| 145 ConcurrentMarkSweepThread::cms_thread_has_cms_token() : | |
| 146 ConcurrentMarkSweepThread::vm_thread_has_cms_token(), | |
| 147 "Incorrect state"); | |
| 148 ConcurrentMarkSweepThread::desynchronize(_is_cms_thread); | |
| 149 } | |
| 150 }; | |
| 151 | |
| 152 // Convenience class that does a CMSTokenSync, and then acquires | |
| 153 // upto three locks. | |
| 154 class CMSTokenSyncWithLocks: public CMSTokenSync { | |
| 155 private: | |
| 156 // Note: locks are acquired in textual declaration order | |
| 157 // and released in the opposite order | |
| 158 MutexLockerEx _locker1, _locker2, _locker3; | |
| 159 public: | |
| 160 CMSTokenSyncWithLocks(bool is_cms_thread, Mutex* mutex1, | |
| 161 Mutex* mutex2 = NULL, Mutex* mutex3 = NULL): | |
| 162 CMSTokenSync(is_cms_thread), | |
| 163 _locker1(mutex1, Mutex::_no_safepoint_check_flag), | |
| 164 _locker2(mutex2, Mutex::_no_safepoint_check_flag), | |
| 165 _locker3(mutex3, Mutex::_no_safepoint_check_flag) | |
| 166 { } | |
| 167 }; | |
| 168 | |
| 169 | |
| 170 // Wrapper class to temporarily disable icms during a foreground cms collection. | |
| 171 class ICMSDisabler: public StackObj { | |
| 172 public: | |
| 173 // The ctor disables icms and wakes up the thread so it notices the change; | |
| 174 // the dtor re-enables icms. Note that the CMSCollector methods will check | |
| 175 // CMSIncrementalMode. | |
| 176 ICMSDisabler() { CMSCollector::disable_icms(); CMSCollector::start_icms(); } | |
| 177 ~ICMSDisabler() { CMSCollector::enable_icms(); } | |
| 178 }; | |
| 179 | |
| 180 ////////////////////////////////////////////////////////////////// | |
| 181 // Concurrent Mark-Sweep Generation ///////////////////////////// | |
| 182 ////////////////////////////////////////////////////////////////// | |
| 183 | |
| 184 NOT_PRODUCT(CompactibleFreeListSpace* debug_cms_space;) | |
| 185 | |
| 186 // This struct contains per-thread things necessary to support parallel | |
| 187 // young-gen collection. | |
| 6197 | 188 class CMSParGCThreadState: public CHeapObj<mtGC> { |
| 0 | 189 public: |
| 190 CFLS_LAB lab; | |
| 191 PromotionInfo promo; | |
| 192 | |
| 193 // Constructor. | |
| 194 CMSParGCThreadState(CompactibleFreeListSpace* cfls) : lab(cfls) { | |
| 195 promo.setSpace(cfls); | |
| 196 } | |
| 197 }; | |
| 198 | |
| 199 ConcurrentMarkSweepGeneration::ConcurrentMarkSweepGeneration( | |
| 200 ReservedSpace rs, size_t initial_byte_size, int level, | |
| 201 CardTableRS* ct, bool use_adaptive_freelists, | |
| 6026 | 202 FreeBlockDictionary<FreeChunk>::DictionaryChoice dictionaryChoice) : |
| 0 | 203 CardGeneration(rs, initial_byte_size, level, ct), |
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204 _dilatation_factor(((double)MinChunkSize)/((double)(CollectedHeap::min_fill_size()))), |
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205 _debug_collection_type(Concurrent_collection_type), |
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206 _did_compact(false) |
| 0 | 207 { |
| 208 HeapWord* bottom = (HeapWord*) _virtual_space.low(); | |
| 209 HeapWord* end = (HeapWord*) _virtual_space.high(); | |
| 210 | |
| 211 _direct_allocated_words = 0; | |
| 212 NOT_PRODUCT( | |
| 213 _numObjectsPromoted = 0; | |
| 214 _numWordsPromoted = 0; | |
| 215 _numObjectsAllocated = 0; | |
| 216 _numWordsAllocated = 0; | |
| 217 ) | |
| 218 | |
| 219 _cmsSpace = new CompactibleFreeListSpace(_bts, MemRegion(bottom, end), | |
| 220 use_adaptive_freelists, | |
| 221 dictionaryChoice); | |
| 222 NOT_PRODUCT(debug_cms_space = _cmsSpace;) | |
| 223 if (_cmsSpace == NULL) { | |
| 224 vm_exit_during_initialization( | |
| 225 "CompactibleFreeListSpace allocation failure"); | |
| 226 } | |
| 227 _cmsSpace->_gen = this; | |
| 228 | |
| 229 _gc_stats = new CMSGCStats(); | |
| 230 | |
| 231 // Verify the assumption that FreeChunk::_prev and OopDesc::_klass | |
| 232 // offsets match. The ability to tell free chunks from objects | |
| 233 // depends on this property. | |
| 234 debug_only( | |
| 235 FreeChunk* junk = NULL; | |
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236 assert(UseCompressedClassPointers || |
| 187 | 237 junk->prev_addr() == (void*)(oop(junk)->klass_addr()), |
| 0 | 238 "Offset of FreeChunk::_prev within FreeChunk must match" |
| 239 " that of OopDesc::_klass within OopDesc"); | |
| 240 ) | |
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241 if (CollectedHeap::use_parallel_gc_threads()) { |
| 0 | 242 typedef CMSParGCThreadState* CMSParGCThreadStatePtr; |
| 243 _par_gc_thread_states = | |
| 6197 | 244 NEW_C_HEAP_ARRAY(CMSParGCThreadStatePtr, ParallelGCThreads, mtGC); |
| 0 | 245 if (_par_gc_thread_states == NULL) { |
| 246 vm_exit_during_initialization("Could not allocate par gc structs"); | |
| 247 } | |
| 248 for (uint i = 0; i < ParallelGCThreads; i++) { | |
| 249 _par_gc_thread_states[i] = new CMSParGCThreadState(cmsSpace()); | |
| 250 if (_par_gc_thread_states[i] == NULL) { | |
| 251 vm_exit_during_initialization("Could not allocate par gc structs"); | |
| 252 } | |
| 253 } | |
| 254 } else { | |
| 255 _par_gc_thread_states = NULL; | |
| 256 } | |
| 257 _incremental_collection_failed = false; | |
| 258 // The "dilatation_factor" is the expansion that can occur on | |
| 259 // account of the fact that the minimum object size in the CMS | |
| 260 // generation may be larger than that in, say, a contiguous young | |
| 261 // generation. | |
| 262 // Ideally, in the calculation below, we'd compute the dilatation | |
| 263 // factor as: MinChunkSize/(promoting_gen's min object size) | |
| 264 // Since we do not have such a general query interface for the | |
| 265 // promoting generation, we'll instead just use the mimimum | |
| 266 // object size (which today is a header's worth of space); | |
| 267 // note that all arithmetic is in units of HeapWords. | |
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268 assert(MinChunkSize >= CollectedHeap::min_fill_size(), "just checking"); |
| 0 | 269 assert(_dilatation_factor >= 1.0, "from previous assert"); |
| 270 } | |
| 271 | |
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272 |
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273 // The field "_initiating_occupancy" represents the occupancy percentage |
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274 // at which we trigger a new collection cycle. Unless explicitly specified |
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275 // via CMSInitiatingOccupancyFraction (argument "io" below), it |
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276 // is calculated by: |
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277 // |
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278 // Let "f" be MinHeapFreeRatio in |
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279 // |
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280 // _intiating_occupancy = 100-f + |
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281 // f * (CMSTriggerRatio/100) |
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282 // where CMSTriggerRatio is the argument "tr" below. |
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283 // |
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284 // That is, if we assume the heap is at its desired maximum occupancy at the |
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285 // end of a collection, we let CMSTriggerRatio of the (purported) free |
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286 // space be allocated before initiating a new collection cycle. |
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287 // |
| 8035 | 288 void ConcurrentMarkSweepGeneration::init_initiating_occupancy(intx io, uintx tr) { |
| 289 assert(io <= 100 && tr <= 100, "Check the arguments"); | |
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290 if (io >= 0) { |
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291 _initiating_occupancy = (double)io / 100.0; |
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292 } else { |
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293 _initiating_occupancy = ((100 - MinHeapFreeRatio) + |
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294 (double)(tr * MinHeapFreeRatio) / 100.0) |
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295 / 100.0; |
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296 } |
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297 } |
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298 |
| 0 | 299 void ConcurrentMarkSweepGeneration::ref_processor_init() { |
| 300 assert(collector() != NULL, "no collector"); | |
| 301 collector()->ref_processor_init(); | |
| 302 } | |
| 303 | |
| 304 void CMSCollector::ref_processor_init() { | |
| 305 if (_ref_processor == NULL) { | |
| 306 // Allocate and initialize a reference processor | |
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307 _ref_processor = |
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308 new ReferenceProcessor(_span, // span |
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309 (ParallelGCThreads > 1) && ParallelRefProcEnabled, // mt processing |
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310 (int) ParallelGCThreads, // mt processing degree |
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311 _cmsGen->refs_discovery_is_mt(), // mt discovery |
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312 (int) MAX2(ConcGCThreads, ParallelGCThreads), // mt discovery degree |
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313 _cmsGen->refs_discovery_is_atomic(), // discovery is not atomic |
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314 &_is_alive_closure); // closure for liveness info |
| 0 | 315 // Initialize the _ref_processor field of CMSGen |
| 316 _cmsGen->set_ref_processor(_ref_processor); | |
| 317 | |
| 318 } | |
| 319 } | |
| 320 | |
| 321 CMSAdaptiveSizePolicy* CMSCollector::size_policy() { | |
| 322 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 323 assert(gch->kind() == CollectedHeap::GenCollectedHeap, | |
| 324 "Wrong type of heap"); | |
| 325 CMSAdaptiveSizePolicy* sp = (CMSAdaptiveSizePolicy*) | |
| 326 gch->gen_policy()->size_policy(); | |
| 327 assert(sp->is_gc_cms_adaptive_size_policy(), | |
| 328 "Wrong type of size policy"); | |
| 329 return sp; | |
| 330 } | |
| 331 | |
| 332 CMSGCAdaptivePolicyCounters* CMSCollector::gc_adaptive_policy_counters() { | |
| 333 CMSGCAdaptivePolicyCounters* results = | |
| 334 (CMSGCAdaptivePolicyCounters*) collector_policy()->counters(); | |
| 335 assert( | |
| 336 results->kind() == GCPolicyCounters::CMSGCAdaptivePolicyCountersKind, | |
| 337 "Wrong gc policy counter kind"); | |
| 338 return results; | |
| 339 } | |
| 340 | |
| 341 | |
| 342 void ConcurrentMarkSweepGeneration::initialize_performance_counters() { | |
| 343 | |
| 344 const char* gen_name = "old"; | |
| 345 | |
| 346 // Generation Counters - generation 1, 1 subspace | |
| 347 _gen_counters = new GenerationCounters(gen_name, 1, 1, &_virtual_space); | |
| 348 | |
| 349 _space_counters = new GSpaceCounters(gen_name, 0, | |
| 350 _virtual_space.reserved_size(), | |
| 351 this, _gen_counters); | |
| 352 } | |
| 353 | |
| 354 CMSStats::CMSStats(ConcurrentMarkSweepGeneration* cms_gen, unsigned int alpha): | |
| 355 _cms_gen(cms_gen) | |
| 356 { | |
| 357 assert(alpha <= 100, "bad value"); | |
| 358 _saved_alpha = alpha; | |
| 359 | |
| 360 // Initialize the alphas to the bootstrap value of 100. | |
| 361 _gc0_alpha = _cms_alpha = 100; | |
| 362 | |
| 363 _cms_begin_time.update(); | |
| 364 _cms_end_time.update(); | |
| 365 | |
| 366 _gc0_duration = 0.0; | |
| 367 _gc0_period = 0.0; | |
| 368 _gc0_promoted = 0; | |
| 369 | |
| 370 _cms_duration = 0.0; | |
| 371 _cms_period = 0.0; | |
| 372 _cms_allocated = 0; | |
| 373 | |
| 374 _cms_used_at_gc0_begin = 0; | |
| 375 _cms_used_at_gc0_end = 0; | |
| 376 _allow_duty_cycle_reduction = false; | |
| 377 _valid_bits = 0; | |
| 378 _icms_duty_cycle = CMSIncrementalDutyCycle; | |
| 379 } | |
| 380 | |
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381 double CMSStats::cms_free_adjustment_factor(size_t free) const { |
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382 // TBD: CR 6909490 |
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383 return 1.0; |
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384 } |
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385 |
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386 void CMSStats::adjust_cms_free_adjustment_factor(bool fail, size_t free) { |
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387 } |
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388 |
| 0 | 389 // If promotion failure handling is on use |
| 390 // the padded average size of the promotion for each | |
| 391 // young generation collection. | |
| 392 double CMSStats::time_until_cms_gen_full() const { | |
| 393 size_t cms_free = _cms_gen->cmsSpace()->free(); | |
| 394 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
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395 size_t expected_promotion = MIN2(gch->get_gen(0)->capacity(), |
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396 (size_t) _cms_gen->gc_stats()->avg_promoted()->padded_average()); |
| 0 | 397 if (cms_free > expected_promotion) { |
| 398 // Start a cms collection if there isn't enough space to promote | |
| 399 // for the next minor collection. Use the padded average as | |
| 400 // a safety factor. | |
| 401 cms_free -= expected_promotion; | |
| 402 | |
| 403 // Adjust by the safety factor. | |
| 404 double cms_free_dbl = (double)cms_free; | |
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405 double cms_adjustment = (100.0 - CMSIncrementalSafetyFactor)/100.0; |
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406 // Apply a further correction factor which tries to adjust |
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407 // for recent occurance of concurrent mode failures. |
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408 cms_adjustment = cms_adjustment * cms_free_adjustment_factor(cms_free); |
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409 cms_free_dbl = cms_free_dbl * cms_adjustment; |
| 0 | 410 |
| 411 if (PrintGCDetails && Verbose) { | |
| 412 gclog_or_tty->print_cr("CMSStats::time_until_cms_gen_full: cms_free " | |
| 413 SIZE_FORMAT " expected_promotion " SIZE_FORMAT, | |
| 414 cms_free, expected_promotion); | |
| 415 gclog_or_tty->print_cr(" cms_free_dbl %f cms_consumption_rate %f", | |
| 416 cms_free_dbl, cms_consumption_rate() + 1.0); | |
| 417 } | |
| 418 // Add 1 in case the consumption rate goes to zero. | |
| 419 return cms_free_dbl / (cms_consumption_rate() + 1.0); | |
| 420 } | |
| 421 return 0.0; | |
| 422 } | |
| 423 | |
| 424 // Compare the duration of the cms collection to the | |
| 425 // time remaining before the cms generation is empty. | |
| 426 // Note that the time from the start of the cms collection | |
| 427 // to the start of the cms sweep (less than the total | |
| 428 // duration of the cms collection) can be used. This | |
| 429 // has been tried and some applications experienced | |
| 430 // promotion failures early in execution. This was | |
| 431 // possibly because the averages were not accurate | |
| 432 // enough at the beginning. | |
| 433 double CMSStats::time_until_cms_start() const { | |
| 434 // We add "gc0_period" to the "work" calculation | |
| 435 // below because this query is done (mostly) at the | |
| 436 // end of a scavenge, so we need to conservatively | |
| 437 // account for that much possible delay | |
| 438 // in the query so as to avoid concurrent mode failures | |
| 439 // due to starting the collection just a wee bit too | |
| 440 // late. | |
| 441 double work = cms_duration() + gc0_period(); | |
| 442 double deadline = time_until_cms_gen_full(); | |
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443 // If a concurrent mode failure occurred recently, we want to be |
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444 // more conservative and halve our expected time_until_cms_gen_full() |
| 0 | 445 if (work > deadline) { |
| 446 if (Verbose && PrintGCDetails) { | |
| 447 gclog_or_tty->print( | |
| 448 " CMSCollector: collect because of anticipated promotion " | |
| 449 "before full %3.7f + %3.7f > %3.7f ", cms_duration(), | |
| 450 gc0_period(), time_until_cms_gen_full()); | |
| 451 } | |
| 452 return 0.0; | |
| 453 } | |
| 454 return work - deadline; | |
| 455 } | |
| 456 | |
| 457 // Return a duty cycle based on old_duty_cycle and new_duty_cycle, limiting the | |
| 458 // amount of change to prevent wild oscillation. | |
| 459 unsigned int CMSStats::icms_damped_duty_cycle(unsigned int old_duty_cycle, | |
| 460 unsigned int new_duty_cycle) { | |
| 461 assert(old_duty_cycle <= 100, "bad input value"); | |
| 462 assert(new_duty_cycle <= 100, "bad input value"); | |
| 463 | |
| 464 // Note: use subtraction with caution since it may underflow (values are | |
| 465 // unsigned). Addition is safe since we're in the range 0-100. | |
| 466 unsigned int damped_duty_cycle = new_duty_cycle; | |
| 467 if (new_duty_cycle < old_duty_cycle) { | |
| 468 const unsigned int largest_delta = MAX2(old_duty_cycle / 4, 5U); | |
| 469 if (new_duty_cycle + largest_delta < old_duty_cycle) { | |
| 470 damped_duty_cycle = old_duty_cycle - largest_delta; | |
| 471 } | |
| 472 } else if (new_duty_cycle > old_duty_cycle) { | |
| 473 const unsigned int largest_delta = MAX2(old_duty_cycle / 4, 15U); | |
| 474 if (new_duty_cycle > old_duty_cycle + largest_delta) { | |
| 475 damped_duty_cycle = MIN2(old_duty_cycle + largest_delta, 100U); | |
| 476 } | |
| 477 } | |
| 478 assert(damped_duty_cycle <= 100, "invalid duty cycle computed"); | |
| 479 | |
| 480 if (CMSTraceIncrementalPacing) { | |
| 481 gclog_or_tty->print(" [icms_damped_duty_cycle(%d,%d) = %d] ", | |
| 482 old_duty_cycle, new_duty_cycle, damped_duty_cycle); | |
| 483 } | |
| 484 return damped_duty_cycle; | |
| 485 } | |
| 486 | |
| 487 unsigned int CMSStats::icms_update_duty_cycle_impl() { | |
| 488 assert(CMSIncrementalPacing && valid(), | |
| 489 "should be handled in icms_update_duty_cycle()"); | |
| 490 | |
| 491 double cms_time_so_far = cms_timer().seconds(); | |
| 492 double scaled_duration = cms_duration_per_mb() * _cms_used_at_gc0_end / M; | |
| 493 double scaled_duration_remaining = fabsd(scaled_duration - cms_time_so_far); | |
| 494 | |
| 495 // Avoid division by 0. | |
| 496 double time_until_full = MAX2(time_until_cms_gen_full(), 0.01); | |
| 497 double duty_cycle_dbl = 100.0 * scaled_duration_remaining / time_until_full; | |
| 498 | |
| 499 unsigned int new_duty_cycle = MIN2((unsigned int)duty_cycle_dbl, 100U); | |
| 500 if (new_duty_cycle > _icms_duty_cycle) { | |
| 501 // Avoid very small duty cycles (1 or 2); 0 is allowed. | |
| 502 if (new_duty_cycle > 2) { | |
| 503 _icms_duty_cycle = icms_damped_duty_cycle(_icms_duty_cycle, | |
| 504 new_duty_cycle); | |
| 505 } | |
| 506 } else if (_allow_duty_cycle_reduction) { | |
| 507 // The duty cycle is reduced only once per cms cycle (see record_cms_end()). | |
| 508 new_duty_cycle = icms_damped_duty_cycle(_icms_duty_cycle, new_duty_cycle); | |
| 509 // Respect the minimum duty cycle. | |
| 510 unsigned int min_duty_cycle = (unsigned int)CMSIncrementalDutyCycleMin; | |
| 511 _icms_duty_cycle = MAX2(new_duty_cycle, min_duty_cycle); | |
| 512 } | |
| 513 | |
| 514 if (PrintGCDetails || CMSTraceIncrementalPacing) { | |
| 515 gclog_or_tty->print(" icms_dc=%d ", _icms_duty_cycle); | |
| 516 } | |
| 517 | |
| 518 _allow_duty_cycle_reduction = false; | |
| 519 return _icms_duty_cycle; | |
| 520 } | |
| 521 | |
| 522 #ifndef PRODUCT | |
| 523 void CMSStats::print_on(outputStream *st) const { | |
| 524 st->print(" gc0_alpha=%d,cms_alpha=%d", _gc0_alpha, _cms_alpha); | |
| 525 st->print(",gc0_dur=%g,gc0_per=%g,gc0_promo=" SIZE_FORMAT, | |
| 526 gc0_duration(), gc0_period(), gc0_promoted()); | |
| 527 st->print(",cms_dur=%g,cms_dur_per_mb=%g,cms_per=%g,cms_alloc=" SIZE_FORMAT, | |
| 528 cms_duration(), cms_duration_per_mb(), | |
| 529 cms_period(), cms_allocated()); | |
| 530 st->print(",cms_since_beg=%g,cms_since_end=%g", | |
| 531 cms_time_since_begin(), cms_time_since_end()); | |
| 532 st->print(",cms_used_beg=" SIZE_FORMAT ",cms_used_end=" SIZE_FORMAT, | |
| 533 _cms_used_at_gc0_begin, _cms_used_at_gc0_end); | |
| 534 if (CMSIncrementalMode) { | |
| 535 st->print(",dc=%d", icms_duty_cycle()); | |
| 536 } | |
| 537 | |
| 538 if (valid()) { | |
| 539 st->print(",promo_rate=%g,cms_alloc_rate=%g", | |
| 540 promotion_rate(), cms_allocation_rate()); | |
| 541 st->print(",cms_consumption_rate=%g,time_until_full=%g", | |
| 542 cms_consumption_rate(), time_until_cms_gen_full()); | |
| 543 } | |
| 544 st->print(" "); | |
| 545 } | |
| 546 #endif // #ifndef PRODUCT | |
| 547 | |
| 548 CMSCollector::CollectorState CMSCollector::_collectorState = | |
| 549 CMSCollector::Idling; | |
| 550 bool CMSCollector::_foregroundGCIsActive = false; | |
| 551 bool CMSCollector::_foregroundGCShouldWait = false; | |
| 552 | |
| 553 CMSCollector::CMSCollector(ConcurrentMarkSweepGeneration* cmsGen, | |
| 554 CardTableRS* ct, | |
| 555 ConcurrentMarkSweepPolicy* cp): | |
| 556 _cmsGen(cmsGen), | |
| 557 _ct(ct), | |
| 558 _ref_processor(NULL), // will be set later | |
| 559 _conc_workers(NULL), // may be set later | |
| 560 _abort_preclean(false), | |
| 561 _start_sampling(false), | |
| 562 _between_prologue_and_epilogue(false), | |
| 563 _markBitMap(0, Mutex::leaf + 1, "CMS_markBitMap_lock"), | |
| 564 _modUnionTable((CardTableModRefBS::card_shift - LogHeapWordSize), | |
| 565 -1 /* lock-free */, "No_lock" /* dummy */), | |
| 566 _modUnionClosure(&_modUnionTable), | |
| 567 _modUnionClosurePar(&_modUnionTable), | |
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568 // Adjust my span to cover old (cms) gen |
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569 _span(cmsGen->reserved()), |
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570 // Construct the is_alive_closure with _span & markBitMap |
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571 _is_alive_closure(_span, &_markBitMap), |
| 0 | 572 _restart_addr(NULL), |
| 573 _overflow_list(NULL), | |
| 574 _stats(cmsGen), | |
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575 _eden_chunk_lock(new Mutex(Mutex::leaf + 1, "CMS_eden_chunk_lock", true)), |
| 0 | 576 _eden_chunk_array(NULL), // may be set in ctor body |
| 577 _eden_chunk_capacity(0), // -- ditto -- | |
| 578 _eden_chunk_index(0), // -- ditto -- | |
| 579 _survivor_plab_array(NULL), // -- ditto -- | |
| 580 _survivor_chunk_array(NULL), // -- ditto -- | |
| 581 _survivor_chunk_capacity(0), // -- ditto -- | |
| 582 _survivor_chunk_index(0), // -- ditto -- | |
| 583 _ser_pmc_preclean_ovflw(0), | |
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584 _ser_kac_preclean_ovflw(0), |
| 0 | 585 _ser_pmc_remark_ovflw(0), |
| 586 _par_pmc_remark_ovflw(0), | |
| 587 _ser_kac_ovflw(0), | |
| 588 _par_kac_ovflw(0), | |
| 589 #ifndef PRODUCT | |
| 590 _num_par_pushes(0), | |
| 591 #endif | |
| 592 _collection_count_start(0), | |
| 593 _verifying(false), | |
| 594 _icms_start_limit(NULL), | |
| 595 _icms_stop_limit(NULL), | |
| 596 _verification_mark_bm(0, Mutex::leaf + 1, "CMS_verification_mark_bm_lock"), | |
| 597 _completed_initialization(false), | |
| 598 _collector_policy(cp), | |
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599 _should_unload_classes(CMSClassUnloadingEnabled), |
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600 _concurrent_cycles_since_last_unload(0), |
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601 _roots_scanning_options(GenCollectedHeap::SO_None), |
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602 _inter_sweep_estimate(CMS_SweepWeight, CMS_SweepPadding), |
| 10405 | 603 _intra_sweep_estimate(CMS_SweepWeight, CMS_SweepPadding), |
| 604 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) CMSTracer()), | |
| 605 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), | |
| 606 _cms_start_registered(false) | |
| 0 | 607 { |
| 608 if (ExplicitGCInvokesConcurrentAndUnloadsClasses) { | |
| 609 ExplicitGCInvokesConcurrent = true; | |
| 610 } | |
| 611 // Now expand the span and allocate the collection support structures | |
| 612 // (MUT, marking bit map etc.) to cover both generations subject to | |
| 613 // collection. | |
| 614 | |
| 615 // For use by dirty card to oop closures. | |
| 616 _cmsGen->cmsSpace()->set_collector(this); | |
| 617 | |
| 618 // Allocate MUT and marking bit map | |
| 619 { | |
| 620 MutexLockerEx x(_markBitMap.lock(), Mutex::_no_safepoint_check_flag); | |
| 621 if (!_markBitMap.allocate(_span)) { | |
| 622 warning("Failed to allocate CMS Bit Map"); | |
| 623 return; | |
| 624 } | |
| 625 assert(_markBitMap.covers(_span), "_markBitMap inconsistency?"); | |
| 626 } | |
| 627 { | |
| 628 _modUnionTable.allocate(_span); | |
| 629 assert(_modUnionTable.covers(_span), "_modUnionTable inconsistency?"); | |
| 630 } | |
| 631 | |
| 1284 | 632 if (!_markStack.allocate(MarkStackSize)) { |
| 0 | 633 warning("Failed to allocate CMS Marking Stack"); |
| 634 return; | |
| 635 } | |
| 636 | |
| 637 // Support for multi-threaded concurrent phases | |
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638 if (CMSConcurrentMTEnabled) { |
| 1284 | 639 if (FLAG_IS_DEFAULT(ConcGCThreads)) { |
| 0 | 640 // just for now |
| 1284 | 641 FLAG_SET_DEFAULT(ConcGCThreads, (ParallelGCThreads + 3)/4); |
| 642 } | |
| 643 if (ConcGCThreads > 1) { | |
| 0 | 644 _conc_workers = new YieldingFlexibleWorkGang("Parallel CMS Threads", |
| 1284 | 645 ConcGCThreads, true); |
| 0 | 646 if (_conc_workers == NULL) { |
| 647 warning("GC/CMS: _conc_workers allocation failure: " | |
| 648 "forcing -CMSConcurrentMTEnabled"); | |
| 649 CMSConcurrentMTEnabled = false; | |
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650 } else { |
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651 _conc_workers->initialize_workers(); |
| 0 | 652 } |
| 653 } else { | |
| 654 CMSConcurrentMTEnabled = false; | |
| 655 } | |
| 656 } | |
| 657 if (!CMSConcurrentMTEnabled) { | |
| 1284 | 658 ConcGCThreads = 0; |
| 0 | 659 } else { |
| 660 // Turn off CMSCleanOnEnter optimization temporarily for | |
| 661 // the MT case where it's not fixed yet; see 6178663. | |
| 662 CMSCleanOnEnter = false; | |
| 663 } | |
| 1284 | 664 assert((_conc_workers != NULL) == (ConcGCThreads > 1), |
| 0 | 665 "Inconsistency"); |
| 666 | |
| 667 // Parallel task queues; these are shared for the | |
| 668 // concurrent and stop-world phases of CMS, but | |
| 669 // are not shared with parallel scavenge (ParNew). | |
| 670 { | |
| 671 uint i; | |
| 1284 | 672 uint num_queues = (uint) MAX2(ParallelGCThreads, ConcGCThreads); |
| 0 | 673 |
| 674 if ((CMSParallelRemarkEnabled || CMSConcurrentMTEnabled | |
| 675 || ParallelRefProcEnabled) | |
| 676 && num_queues > 0) { | |
| 677 _task_queues = new OopTaskQueueSet(num_queues); | |
| 678 if (_task_queues == NULL) { | |
| 679 warning("task_queues allocation failure."); | |
| 680 return; | |
| 681 } | |
| 6197 | 682 _hash_seed = NEW_C_HEAP_ARRAY(int, num_queues, mtGC); |
| 0 | 683 if (_hash_seed == NULL) { |
| 684 warning("_hash_seed array allocation failure"); | |
| 685 return; | |
| 686 } | |
| 687 | |
| 1665 | 688 typedef Padded<OopTaskQueue> PaddedOopTaskQueue; |
| 0 | 689 for (i = 0; i < num_queues; i++) { |
| 1665 | 690 PaddedOopTaskQueue *q = new PaddedOopTaskQueue(); |
| 691 if (q == NULL) { | |
| 0 | 692 warning("work_queue allocation failure."); |
| 693 return; | |
| 694 } | |
| 1665 | 695 _task_queues->register_queue(i, q); |
| 0 | 696 } |
| 697 for (i = 0; i < num_queues; i++) { | |
| 698 _task_queues->queue(i)->initialize(); | |
| 699 _hash_seed[i] = 17; // copied from ParNew | |
| 700 } | |
| 701 } | |
| 702 } | |
| 703 | |
|
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704 _cmsGen ->init_initiating_occupancy(CMSInitiatingOccupancyFraction, CMSTriggerRatio); |
|
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705 |
| 0 | 706 // Clip CMSBootstrapOccupancy between 0 and 100. |
|
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707 _bootstrap_occupancy = ((double)CMSBootstrapOccupancy)/(double)100; |
| 0 | 708 |
| 709 _full_gcs_since_conc_gc = 0; | |
| 710 | |
| 711 // Now tell CMS generations the identity of their collector | |
| 712 ConcurrentMarkSweepGeneration::set_collector(this); | |
| 713 | |
| 714 // Create & start a CMS thread for this CMS collector | |
| 715 _cmsThread = ConcurrentMarkSweepThread::start(this); | |
| 716 assert(cmsThread() != NULL, "CMS Thread should have been created"); | |
| 717 assert(cmsThread()->collector() == this, | |
| 718 "CMS Thread should refer to this gen"); | |
| 719 assert(CGC_lock != NULL, "Where's the CGC_lock?"); | |
| 720 | |
| 721 // Support for parallelizing young gen rescan | |
| 722 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 723 _young_gen = gch->prev_gen(_cmsGen); | |
| 724 if (gch->supports_inline_contig_alloc()) { | |
| 725 _top_addr = gch->top_addr(); | |
| 726 _end_addr = gch->end_addr(); | |
| 727 assert(_young_gen != NULL, "no _young_gen"); | |
| 728 _eden_chunk_index = 0; | |
| 729 _eden_chunk_capacity = (_young_gen->max_capacity()+CMSSamplingGrain)/CMSSamplingGrain; | |
| 6197 | 730 _eden_chunk_array = NEW_C_HEAP_ARRAY(HeapWord*, _eden_chunk_capacity, mtGC); |
| 0 | 731 if (_eden_chunk_array == NULL) { |
| 732 _eden_chunk_capacity = 0; | |
| 733 warning("GC/CMS: _eden_chunk_array allocation failure"); | |
| 734 } | |
| 735 } | |
| 736 assert(_eden_chunk_array != NULL || _eden_chunk_capacity == 0, "Error"); | |
| 737 | |
| 738 // Support for parallelizing survivor space rescan | |
| 11975 | 739 if ((CMSParallelRemarkEnabled && CMSParallelSurvivorRemarkEnabled) || CMSParallelInitialMarkEnabled) { |
|
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740 const size_t max_plab_samples = |
| 20756 | 741 ((DefNewGeneration*)_young_gen)->max_survivor_size() / plab_sample_minimum_size(); |
|
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742 |
| 6197 | 743 _survivor_plab_array = NEW_C_HEAP_ARRAY(ChunkArray, ParallelGCThreads, mtGC); |
| 744 _survivor_chunk_array = NEW_C_HEAP_ARRAY(HeapWord*, 2*max_plab_samples, mtGC); | |
| 745 _cursor = NEW_C_HEAP_ARRAY(size_t, ParallelGCThreads, mtGC); | |
| 0 | 746 if (_survivor_plab_array == NULL || _survivor_chunk_array == NULL |
| 747 || _cursor == NULL) { | |
| 748 warning("Failed to allocate survivor plab/chunk array"); | |
| 749 if (_survivor_plab_array != NULL) { | |
| 6197 | 750 FREE_C_HEAP_ARRAY(ChunkArray, _survivor_plab_array, mtGC); |
| 0 | 751 _survivor_plab_array = NULL; |
| 752 } | |
| 753 if (_survivor_chunk_array != NULL) { | |
| 6197 | 754 FREE_C_HEAP_ARRAY(HeapWord*, _survivor_chunk_array, mtGC); |
| 0 | 755 _survivor_chunk_array = NULL; |
| 756 } | |
| 757 if (_cursor != NULL) { | |
| 6197 | 758 FREE_C_HEAP_ARRAY(size_t, _cursor, mtGC); |
| 0 | 759 _cursor = NULL; |
| 760 } | |
| 761 } else { | |
| 762 _survivor_chunk_capacity = 2*max_plab_samples; | |
| 763 for (uint i = 0; i < ParallelGCThreads; i++) { | |
| 6197 | 764 HeapWord** vec = NEW_C_HEAP_ARRAY(HeapWord*, max_plab_samples, mtGC); |
| 0 | 765 if (vec == NULL) { |
| 766 warning("Failed to allocate survivor plab array"); | |
| 767 for (int j = i; j > 0; j--) { | |
| 6197 | 768 FREE_C_HEAP_ARRAY(HeapWord*, _survivor_plab_array[j-1].array(), mtGC); |
| 0 | 769 } |
| 6197 | 770 FREE_C_HEAP_ARRAY(ChunkArray, _survivor_plab_array, mtGC); |
| 771 FREE_C_HEAP_ARRAY(HeapWord*, _survivor_chunk_array, mtGC); | |
| 0 | 772 _survivor_plab_array = NULL; |
| 773 _survivor_chunk_array = NULL; | |
| 774 _survivor_chunk_capacity = 0; | |
| 775 break; | |
| 776 } else { | |
| 777 ChunkArray* cur = | |
| 778 ::new (&_survivor_plab_array[i]) ChunkArray(vec, | |
| 779 max_plab_samples); | |
| 780 assert(cur->end() == 0, "Should be 0"); | |
| 781 assert(cur->array() == vec, "Should be vec"); | |
| 782 assert(cur->capacity() == max_plab_samples, "Error"); | |
| 783 } | |
| 784 } | |
| 785 } | |
| 786 } | |
| 787 assert( ( _survivor_plab_array != NULL | |
| 788 && _survivor_chunk_array != NULL) | |
| 789 || ( _survivor_chunk_capacity == 0 | |
| 790 && _survivor_chunk_index == 0), | |
| 791 "Error"); | |
| 792 | |
| 793 NOT_PRODUCT(_overflow_counter = CMSMarkStackOverflowInterval;) | |
| 794 _gc_counters = new CollectorCounters("CMS", 1); | |
| 795 _completed_initialization = true; | |
|
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796 _inter_sweep_timer.start(); // start of time |
| 0 | 797 } |
| 798 | |
| 20756 | 799 size_t CMSCollector::plab_sample_minimum_size() { |
| 800 // The default value of MinTLABSize is 2k, but there is | |
| 801 // no way to get the default value if the flag has been overridden. | |
| 802 return MAX2(ThreadLocalAllocBuffer::min_size() * HeapWordSize, 2 * K); | |
| 803 } | |
| 804 | |
| 0 | 805 const char* ConcurrentMarkSweepGeneration::name() const { |
| 806 return "concurrent mark-sweep generation"; | |
| 807 } | |
| 808 void ConcurrentMarkSweepGeneration::update_counters() { | |
| 809 if (UsePerfData) { | |
| 810 _space_counters->update_all(); | |
| 811 _gen_counters->update_all(); | |
| 812 } | |
| 813 } | |
| 814 | |
| 815 // this is an optimized version of update_counters(). it takes the | |
| 816 // used value as a parameter rather than computing it. | |
| 817 // | |
| 818 void ConcurrentMarkSweepGeneration::update_counters(size_t used) { | |
| 819 if (UsePerfData) { | |
| 820 _space_counters->update_used(used); | |
| 821 _space_counters->update_capacity(); | |
| 822 _gen_counters->update_all(); | |
| 823 } | |
| 824 } | |
| 825 | |
| 826 void ConcurrentMarkSweepGeneration::print() const { | |
| 827 Generation::print(); | |
| 828 cmsSpace()->print(); | |
| 829 } | |
| 830 | |
| 831 #ifndef PRODUCT | |
| 832 void ConcurrentMarkSweepGeneration::print_statistics() { | |
| 833 cmsSpace()->printFLCensus(0); | |
| 834 } | |
| 835 #endif | |
| 836 | |
| 837 void ConcurrentMarkSweepGeneration::printOccupancy(const char *s) { | |
| 838 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 839 if (PrintGCDetails) { | |
| 840 if (Verbose) { | |
|
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841 gclog_or_tty->print("[%d %s-%s: "SIZE_FORMAT"("SIZE_FORMAT")]", |
| 0 | 842 level(), short_name(), s, used(), capacity()); |
| 843 } else { | |
|
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844 gclog_or_tty->print("[%d %s-%s: "SIZE_FORMAT"K("SIZE_FORMAT"K)]", |
| 0 | 845 level(), short_name(), s, used() / K, capacity() / K); |
| 846 } | |
| 847 } | |
| 848 if (Verbose) { | |
| 849 gclog_or_tty->print(" "SIZE_FORMAT"("SIZE_FORMAT")", | |
| 850 gch->used(), gch->capacity()); | |
| 851 } else { | |
| 852 gclog_or_tty->print(" "SIZE_FORMAT"K("SIZE_FORMAT"K)", | |
| 853 gch->used() / K, gch->capacity() / K); | |
| 854 } | |
| 855 } | |
| 856 | |
| 857 size_t | |
| 858 ConcurrentMarkSweepGeneration::contiguous_available() const { | |
| 859 // dld proposes an improvement in precision here. If the committed | |
| 860 // part of the space ends in a free block we should add that to | |
| 861 // uncommitted size in the calculation below. Will make this | |
| 862 // change later, staying with the approximation below for the | |
| 863 // time being. -- ysr. | |
| 864 return MAX2(_virtual_space.uncommitted_size(), unsafe_max_alloc_nogc()); | |
| 865 } | |
| 866 | |
| 867 size_t | |
| 868 ConcurrentMarkSweepGeneration::unsafe_max_alloc_nogc() const { | |
| 869 return _cmsSpace->max_alloc_in_words() * HeapWordSize; | |
| 870 } | |
| 871 | |
| 872 size_t ConcurrentMarkSweepGeneration::max_available() const { | |
| 873 return free() + _virtual_space.uncommitted_size(); | |
| 874 } | |
| 875 | |
|
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876 bool ConcurrentMarkSweepGeneration::promotion_attempt_is_safe(size_t max_promotion_in_bytes) const { |
|
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877 size_t available = max_available(); |
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878 size_t av_promo = (size_t)gc_stats()->avg_promoted()->padded_average(); |
|
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879 bool res = (available >= av_promo) || (available >= max_promotion_in_bytes); |
|
1994
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7001033: assert(gch->gc_cause() == GCCause::_scavenge_alot || !gch->incremental_collection_failed())
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|
880 if (Verbose && PrintGCDetails) { |
|
1888
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|
881 gclog_or_tty->print_cr( |
|
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882 "CMS: promo attempt is%s safe: available("SIZE_FORMAT") %s av_promo("SIZE_FORMAT")," |
|
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|
883 "max_promo("SIZE_FORMAT")", |
|
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|
884 res? "":" not", available, res? ">=":"<", |
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885 av_promo, max_promotion_in_bytes); |
|
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|
886 } |
|
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|
887 return res; |
| 0 | 888 } |
| 889 | |
|
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890 // At a promotion failure dump information on block layout in heap |
|
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|
891 // (cms old generation). |
|
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892 void ConcurrentMarkSweepGeneration::promotion_failure_occurred() { |
|
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|
893 if (CMSDumpAtPromotionFailure) { |
|
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|
894 cmsSpace()->dump_at_safepoint_with_locks(collector(), gclog_or_tty); |
|
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diff
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|
895 } |
|
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|
896 } |
|
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|
897 |
| 0 | 898 CompactibleSpace* |
| 899 ConcurrentMarkSweepGeneration::first_compaction_space() const { | |
| 900 return _cmsSpace; | |
| 901 } | |
| 902 | |
| 903 void ConcurrentMarkSweepGeneration::reset_after_compaction() { | |
| 904 // Clear the promotion information. These pointers can be adjusted | |
| 905 // along with all the other pointers into the heap but | |
| 906 // compaction is expected to be a rare event with | |
| 907 // a heap using cms so don't do it without seeing the need. | |
|
1833
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6984287: Regularize how GC parallel workers are specified.
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|
908 if (CollectedHeap::use_parallel_gc_threads()) { |
| 0 | 909 for (uint i = 0; i < ParallelGCThreads; i++) { |
| 910 _par_gc_thread_states[i]->promo.reset(); | |
| 911 } | |
| 912 } | |
| 913 } | |
| 914 | |
| 915 void ConcurrentMarkSweepGeneration::space_iterate(SpaceClosure* blk, bool usedOnly) { | |
| 916 blk->do_space(_cmsSpace); | |
| 917 } | |
| 918 | |
| 919 void ConcurrentMarkSweepGeneration::compute_new_size() { | |
| 920 assert_locked_or_safepoint(Heap_lock); | |
| 921 | |
| 922 // If incremental collection failed, we just want to expand | |
| 923 // to the limit. | |
| 924 if (incremental_collection_failed()) { | |
| 925 clear_incremental_collection_failed(); | |
| 926 grow_to_reserved(); | |
| 927 return; | |
| 928 } | |
| 929 | |
|
10243
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8013032: CMS: assert(used() == used_after_gc && used_after_gc <= capacity()) failed: used: 0 used_after_gc: 292080 capacity: 1431699456
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930 // The heap has been compacted but not reset yet. |
|
a9d568b7df60
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931 // Any metric such as free() or used() will be incorrect. |
|
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932 |
|
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|
933 CardGeneration::compute_new_size(); |
|
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934 |
|
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|
935 // Reset again after a possible resizing |
|
10244
06ab37f08701
8013184: CMS: Call reset_after_compaction() only if a compaction has been done
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|
936 if (did_compact()) { |
|
06ab37f08701
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|
937 cmsSpace()->reset_after_compaction(); |
|
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938 } |
|
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|
939 } |
|
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|
940 |
|
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941 void ConcurrentMarkSweepGeneration::compute_new_size_free_list() { |
|
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942 assert_locked_or_safepoint(Heap_lock); |
|
8617e38bb4cb
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943 |
|
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944 // If incremental collection failed, we just want to expand |
|
8617e38bb4cb
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|
945 // to the limit. |
|
8617e38bb4cb
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|
946 if (incremental_collection_failed()) { |
|
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|
947 clear_incremental_collection_failed(); |
|
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|
948 grow_to_reserved(); |
|
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|
949 return; |
|
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|
950 } |
|
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|
951 |
| 0 | 952 double free_percentage = ((double) free()) / capacity(); |
| 953 double desired_free_percentage = (double) MinHeapFreeRatio / 100; | |
| 954 double maximum_free_percentage = (double) MaxHeapFreeRatio / 100; | |
| 955 | |
| 956 // compute expansion delta needed for reaching desired free percentage | |
| 957 if (free_percentage < desired_free_percentage) { | |
| 958 size_t desired_capacity = (size_t)(used() / ((double) 1 - desired_free_percentage)); | |
| 959 assert(desired_capacity >= capacity(), "invalid expansion size"); | |
|
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960 size_t expand_bytes = MAX2(desired_capacity - capacity(), MinHeapDeltaBytes); |
| 0 | 961 if (PrintGCDetails && Verbose) { |
| 962 size_t desired_capacity = (size_t)(used() / ((double) 1 - desired_free_percentage)); | |
| 963 gclog_or_tty->print_cr("\nFrom compute_new_size: "); | |
| 964 gclog_or_tty->print_cr(" Free fraction %f", free_percentage); | |
| 965 gclog_or_tty->print_cr(" Desired free fraction %f", | |
| 966 desired_free_percentage); | |
| 967 gclog_or_tty->print_cr(" Maximum free fraction %f", | |
| 968 maximum_free_percentage); | |
| 969 gclog_or_tty->print_cr(" Capactiy "SIZE_FORMAT, capacity()/1000); | |
| 970 gclog_or_tty->print_cr(" Desired capacity "SIZE_FORMAT, | |
| 971 desired_capacity/1000); | |
| 972 int prev_level = level() - 1; | |
| 973 if (prev_level >= 0) { | |
| 974 size_t prev_size = 0; | |
| 975 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 976 Generation* prev_gen = gch->_gens[prev_level]; | |
| 977 prev_size = prev_gen->capacity(); | |
| 978 gclog_or_tty->print_cr(" Younger gen size "SIZE_FORMAT, | |
| 979 prev_size/1000); | |
| 980 } | |
| 981 gclog_or_tty->print_cr(" unsafe_max_alloc_nogc "SIZE_FORMAT, | |
| 982 unsafe_max_alloc_nogc()/1000); | |
| 983 gclog_or_tty->print_cr(" contiguous available "SIZE_FORMAT, | |
| 984 contiguous_available()/1000); | |
| 985 gclog_or_tty->print_cr(" Expand by "SIZE_FORMAT" (bytes)", | |
| 986 expand_bytes); | |
| 987 } | |
| 988 // safe if expansion fails | |
| 989 expand(expand_bytes, 0, CMSExpansionCause::_satisfy_free_ratio); | |
| 990 if (PrintGCDetails && Verbose) { | |
| 991 gclog_or_tty->print_cr(" Expanded free fraction %f", | |
| 992 ((double) free()) / capacity()); | |
| 993 } | |
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994 } else { |
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995 size_t desired_capacity = (size_t)(used() / ((double) 1 - desired_free_percentage)); |
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996 assert(desired_capacity <= capacity(), "invalid expansion size"); |
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997 size_t shrink_bytes = capacity() - desired_capacity; |
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998 // Don't shrink unless the delta is greater than the minimum shrink we want |
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999 if (shrink_bytes >= MinHeapDeltaBytes) { |
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1000 shrink_free_list_by(shrink_bytes); |
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1001 } |
| 0 | 1002 } |
| 1003 } | |
| 1004 | |
| 1005 Mutex* ConcurrentMarkSweepGeneration::freelistLock() const { | |
| 1006 return cmsSpace()->freelistLock(); | |
| 1007 } | |
| 1008 | |
| 1009 HeapWord* ConcurrentMarkSweepGeneration::allocate(size_t size, | |
| 1010 bool tlab) { | |
| 1011 CMSSynchronousYieldRequest yr; | |
| 1012 MutexLockerEx x(freelistLock(), | |
| 1013 Mutex::_no_safepoint_check_flag); | |
| 1014 return have_lock_and_allocate(size, tlab); | |
| 1015 } | |
| 1016 | |
| 1017 HeapWord* ConcurrentMarkSweepGeneration::have_lock_and_allocate(size_t size, | |
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1018 bool tlab /* ignored */) { |
| 0 | 1019 assert_lock_strong(freelistLock()); |
| 1020 size_t adjustedSize = CompactibleFreeListSpace::adjustObjectSize(size); | |
| 1021 HeapWord* res = cmsSpace()->allocate(adjustedSize); | |
| 1022 // Allocate the object live (grey) if the background collector has | |
| 1023 // started marking. This is necessary because the marker may | |
| 1024 // have passed this address and consequently this object will | |
| 1025 // not otherwise be greyed and would be incorrectly swept up. | |
| 1026 // Note that if this object contains references, the writing | |
| 1027 // of those references will dirty the card containing this object | |
| 1028 // allowing the object to be blackened (and its references scanned) | |
| 1029 // either during a preclean phase or at the final checkpoint. | |
| 1030 if (res != NULL) { | |
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1031 // We may block here with an uninitialized object with |
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1032 // its mark-bit or P-bits not yet set. Such objects need |
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1033 // to be safely navigable by block_start(). |
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1034 assert(oop(res)->klass_or_null() == NULL, "Object should be uninitialized here."); |
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1035 assert(!((FreeChunk*)res)->is_free(), "Error, block will look free but show wrong size"); |
| 0 | 1036 collector()->direct_allocated(res, adjustedSize); |
| 1037 _direct_allocated_words += adjustedSize; | |
| 1038 // allocation counters | |
| 1039 NOT_PRODUCT( | |
| 1040 _numObjectsAllocated++; | |
| 1041 _numWordsAllocated += (int)adjustedSize; | |
| 1042 ) | |
| 1043 } | |
| 1044 return res; | |
| 1045 } | |
| 1046 | |
| 1047 // In the case of direct allocation by mutators in a generation that | |
| 1048 // is being concurrently collected, the object must be allocated | |
| 1049 // live (grey) if the background collector has started marking. | |
| 1050 // This is necessary because the marker may | |
| 1051 // have passed this address and consequently this object will | |
| 1052 // not otherwise be greyed and would be incorrectly swept up. | |
| 1053 // Note that if this object contains references, the writing | |
| 1054 // of those references will dirty the card containing this object | |
| 1055 // allowing the object to be blackened (and its references scanned) | |
| 1056 // either during a preclean phase or at the final checkpoint. | |
| 1057 void CMSCollector::direct_allocated(HeapWord* start, size_t size) { | |
| 1058 assert(_markBitMap.covers(start, size), "Out of bounds"); | |
| 1059 if (_collectorState >= Marking) { | |
| 1060 MutexLockerEx y(_markBitMap.lock(), | |
| 1061 Mutex::_no_safepoint_check_flag); | |
| 1062 // [see comments preceding SweepClosure::do_blk() below for details] | |
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1063 // |
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1064 // Can the P-bits be deleted now? JJJ |
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1065 // |
| 0 | 1066 // 1. need to mark the object as live so it isn't collected |
| 1067 // 2. need to mark the 2nd bit to indicate the object may be uninitialized | |
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1068 // 3. need to mark the end of the object so marking, precleaning or sweeping |
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1069 // can skip over uninitialized or unparsable objects. An allocated |
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1070 // object is considered uninitialized for our purposes as long as |
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1071 // its klass word is NULL. All old gen objects are parsable |
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1072 // as soon as they are initialized.) |
| 0 | 1073 _markBitMap.mark(start); // object is live |
| 1074 _markBitMap.mark(start + 1); // object is potentially uninitialized? | |
| 1075 _markBitMap.mark(start + size - 1); | |
| 1076 // mark end of object | |
| 1077 } | |
| 1078 // check that oop looks uninitialized | |
| 187 | 1079 assert(oop(start)->klass_or_null() == NULL, "_klass should be NULL"); |
| 0 | 1080 } |
| 1081 | |
| 1082 void CMSCollector::promoted(bool par, HeapWord* start, | |
| 1083 bool is_obj_array, size_t obj_size) { | |
| 1084 assert(_markBitMap.covers(start), "Out of bounds"); | |
| 1085 // See comment in direct_allocated() about when objects should | |
| 1086 // be allocated live. | |
| 1087 if (_collectorState >= Marking) { | |
| 1088 // we already hold the marking bit map lock, taken in | |
| 1089 // the prologue | |
| 1090 if (par) { | |
| 1091 _markBitMap.par_mark(start); | |
| 1092 } else { | |
| 1093 _markBitMap.mark(start); | |
| 1094 } | |
| 1095 // We don't need to mark the object as uninitialized (as | |
| 1096 // in direct_allocated above) because this is being done with the | |
| 1097 // world stopped and the object will be initialized by the | |
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1098 // time the marking, precleaning or sweeping get to look at it. |
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1099 // But see the code for copying objects into the CMS generation, |
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1100 // where we need to ensure that concurrent readers of the |
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1101 // block offset table are able to safely navigate a block that |
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1102 // is in flux from being free to being allocated (and in |
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1103 // transition while being copied into) and subsequently |
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1104 // becoming a bona-fide object when the copy/promotion is complete. |
| 0 | 1105 assert(SafepointSynchronize::is_at_safepoint(), |
| 1106 "expect promotion only at safepoints"); | |
| 1107 | |
| 1108 if (_collectorState < Sweeping) { | |
| 1109 // Mark the appropriate cards in the modUnionTable, so that | |
| 1110 // this object gets scanned before the sweep. If this is | |
| 1111 // not done, CMS generation references in the object might | |
| 1112 // not get marked. | |
| 1113 // For the case of arrays, which are otherwise precisely | |
| 1114 // marked, we need to dirty the entire array, not just its head. | |
| 1115 if (is_obj_array) { | |
| 1116 // The [par_]mark_range() method expects mr.end() below to | |
| 1117 // be aligned to the granularity of a bit's representation | |
| 1118 // in the heap. In the case of the MUT below, that's a | |
| 1119 // card size. | |
| 1120 MemRegion mr(start, | |
| 1121 (HeapWord*)round_to((intptr_t)(start + obj_size), | |
| 1122 CardTableModRefBS::card_size /* bytes */)); | |
| 1123 if (par) { | |
| 1124 _modUnionTable.par_mark_range(mr); | |
| 1125 } else { | |
| 1126 _modUnionTable.mark_range(mr); | |
| 1127 } | |
| 1128 } else { // not an obj array; we can just mark the head | |
| 1129 if (par) { | |
| 1130 _modUnionTable.par_mark(start); | |
| 1131 } else { | |
| 1132 _modUnionTable.mark(start); | |
| 1133 } | |
| 1134 } | |
| 1135 } | |
| 1136 } | |
| 1137 } | |
| 1138 | |
| 1139 static inline size_t percent_of_space(Space* space, HeapWord* addr) | |
| 1140 { | |
| 1141 size_t delta = pointer_delta(addr, space->bottom()); | |
| 1142 return (size_t)(delta * 100.0 / (space->capacity() / HeapWordSize)); | |
| 1143 } | |
| 1144 | |
| 1145 void CMSCollector::icms_update_allocation_limits() | |
| 1146 { | |
| 1147 Generation* gen0 = GenCollectedHeap::heap()->get_gen(0); | |
| 1148 EdenSpace* eden = gen0->as_DefNewGeneration()->eden(); | |
| 1149 | |
| 1150 const unsigned int duty_cycle = stats().icms_update_duty_cycle(); | |
| 1151 if (CMSTraceIncrementalPacing) { | |
| 1152 stats().print(); | |
| 1153 } | |
| 1154 | |
| 1155 assert(duty_cycle <= 100, "invalid duty cycle"); | |
| 1156 if (duty_cycle != 0) { | |
| 1157 // The duty_cycle is a percentage between 0 and 100; convert to words and | |
| 1158 // then compute the offset from the endpoints of the space. | |
| 1159 size_t free_words = eden->free() / HeapWordSize; | |
| 1160 double free_words_dbl = (double)free_words; | |
| 1161 size_t duty_cycle_words = (size_t)(free_words_dbl * duty_cycle / 100.0); | |
| 1162 size_t offset_words = (free_words - duty_cycle_words) / 2; | |
| 1163 | |
| 1164 _icms_start_limit = eden->top() + offset_words; | |
| 1165 _icms_stop_limit = eden->end() - offset_words; | |
| 1166 | |
| 1167 // The limits may be adjusted (shifted to the right) by | |
| 1168 // CMSIncrementalOffset, to allow the application more mutator time after a | |
| 1169 // young gen gc (when all mutators were stopped) and before CMS starts and | |
| 1170 // takes away one or more cpus. | |
| 1171 if (CMSIncrementalOffset != 0) { | |
| 1172 double adjustment_dbl = free_words_dbl * CMSIncrementalOffset / 100.0; | |
| 1173 size_t adjustment = (size_t)adjustment_dbl; | |
| 1174 HeapWord* tmp_stop = _icms_stop_limit + adjustment; | |
| 1175 if (tmp_stop > _icms_stop_limit && tmp_stop < eden->end()) { | |
| 1176 _icms_start_limit += adjustment; | |
| 1177 _icms_stop_limit = tmp_stop; | |
| 1178 } | |
| 1179 } | |
| 1180 } | |
| 1181 if (duty_cycle == 0 || (_icms_start_limit == _icms_stop_limit)) { | |
| 1182 _icms_start_limit = _icms_stop_limit = eden->end(); | |
| 1183 } | |
| 1184 | |
| 1185 // Install the new start limit. | |
| 1186 eden->set_soft_end(_icms_start_limit); | |
| 1187 | |
| 1188 if (CMSTraceIncrementalMode) { | |
| 1189 gclog_or_tty->print(" icms alloc limits: " | |
| 1190 PTR_FORMAT "," PTR_FORMAT | |
| 1191 " (" SIZE_FORMAT "%%," SIZE_FORMAT "%%) ", | |
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1192 p2i(_icms_start_limit), p2i(_icms_stop_limit), |
| 0 | 1193 percent_of_space(eden, _icms_start_limit), |
| 1194 percent_of_space(eden, _icms_stop_limit)); | |
| 1195 if (Verbose) { | |
| 1196 gclog_or_tty->print("eden: "); | |
| 1197 eden->print_on(gclog_or_tty); | |
| 1198 } | |
| 1199 } | |
| 1200 } | |
| 1201 | |
| 1202 // Any changes here should try to maintain the invariant | |
| 1203 // that if this method is called with _icms_start_limit | |
| 1204 // and _icms_stop_limit both NULL, then it should return NULL | |
| 1205 // and not notify the icms thread. | |
| 1206 HeapWord* | |
| 1207 CMSCollector::allocation_limit_reached(Space* space, HeapWord* top, | |
| 1208 size_t word_size) | |
| 1209 { | |
| 1210 // A start_limit equal to end() means the duty cycle is 0, so treat that as a | |
| 1211 // nop. | |
| 1212 if (CMSIncrementalMode && _icms_start_limit != space->end()) { | |
| 1213 if (top <= _icms_start_limit) { | |
| 1214 if (CMSTraceIncrementalMode) { | |
| 1215 space->print_on(gclog_or_tty); | |
| 1216 gclog_or_tty->stamp(); | |
| 1217 gclog_or_tty->print_cr(" start limit top=" PTR_FORMAT | |
| 1218 ", new limit=" PTR_FORMAT | |
| 1219 " (" SIZE_FORMAT "%%)", | |
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1220 p2i(top), p2i(_icms_stop_limit), |
| 0 | 1221 percent_of_space(space, _icms_stop_limit)); |
| 1222 } | |
| 1223 ConcurrentMarkSweepThread::start_icms(); | |
| 1224 assert(top < _icms_stop_limit, "Tautology"); | |
| 1225 if (word_size < pointer_delta(_icms_stop_limit, top)) { | |
| 1226 return _icms_stop_limit; | |
| 1227 } | |
| 1228 | |
| 1229 // The allocation will cross both the _start and _stop limits, so do the | |
| 1230 // stop notification also and return end(). | |
| 1231 if (CMSTraceIncrementalMode) { | |
| 1232 space->print_on(gclog_or_tty); | |
| 1233 gclog_or_tty->stamp(); | |
| 1234 gclog_or_tty->print_cr(" +stop limit top=" PTR_FORMAT | |
| 1235 ", new limit=" PTR_FORMAT | |
| 1236 " (" SIZE_FORMAT "%%)", | |
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1237 p2i(top), p2i(space->end()), |
| 0 | 1238 percent_of_space(space, space->end())); |
| 1239 } | |
| 1240 ConcurrentMarkSweepThread::stop_icms(); | |
| 1241 return space->end(); | |
| 1242 } | |
| 1243 | |
| 1244 if (top <= _icms_stop_limit) { | |
| 1245 if (CMSTraceIncrementalMode) { | |
| 1246 space->print_on(gclog_or_tty); | |
| 1247 gclog_or_tty->stamp(); | |
| 1248 gclog_or_tty->print_cr(" stop limit top=" PTR_FORMAT | |
| 1249 ", new limit=" PTR_FORMAT | |
| 1250 " (" SIZE_FORMAT "%%)", | |
| 1251 top, space->end(), | |
| 1252 percent_of_space(space, space->end())); | |
| 1253 } | |
| 1254 ConcurrentMarkSweepThread::stop_icms(); | |
| 1255 return space->end(); | |
| 1256 } | |
| 1257 | |
| 1258 if (CMSTraceIncrementalMode) { | |
| 1259 space->print_on(gclog_or_tty); | |
| 1260 gclog_or_tty->stamp(); | |
| 1261 gclog_or_tty->print_cr(" end limit top=" PTR_FORMAT | |
| 1262 ", new limit=" PTR_FORMAT, | |
| 1263 top, NULL); | |
| 1264 } | |
| 1265 } | |
| 1266 | |
| 1267 return NULL; | |
| 1268 } | |
| 1269 | |
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1270 oop ConcurrentMarkSweepGeneration::promote(oop obj, size_t obj_size) { |
| 0 | 1271 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in"); |
| 1272 // allocate, copy and if necessary update promoinfo -- | |
| 1273 // delegate to underlying space. | |
| 1274 assert_lock_strong(freelistLock()); | |
| 1275 | |
| 1276 #ifndef PRODUCT | |
| 1277 if (Universe::heap()->promotion_should_fail()) { | |
| 1278 return NULL; | |
| 1279 } | |
| 1280 #endif // #ifndef PRODUCT | |
| 1281 | |
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1282 oop res = _cmsSpace->promote(obj, obj_size); |
| 0 | 1283 if (res == NULL) { |
| 1284 // expand and retry | |
| 1285 size_t s = _cmsSpace->expansionSpaceRequired(obj_size); // HeapWords | |
| 1286 expand(s*HeapWordSize, MinHeapDeltaBytes, | |
| 1287 CMSExpansionCause::_satisfy_promotion); | |
| 1288 // Since there's currently no next generation, we don't try to promote | |
| 1289 // into a more senior generation. | |
| 1290 assert(next_gen() == NULL, "assumption, based upon which no attempt " | |
| 1291 "is made to pass on a possibly failing " | |
| 1292 "promotion to next generation"); | |
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1293 res = _cmsSpace->promote(obj, obj_size); |
| 0 | 1294 } |
| 1295 if (res != NULL) { | |
| 1296 // See comment in allocate() about when objects should | |
| 1297 // be allocated live. | |
| 1298 assert(obj->is_oop(), "Will dereference klass pointer below"); | |
| 1299 collector()->promoted(false, // Not parallel | |
| 1300 (HeapWord*)res, obj->is_objArray(), obj_size); | |
| 1301 // promotion counters | |
| 1302 NOT_PRODUCT( | |
| 1303 _numObjectsPromoted++; | |
| 1304 _numWordsPromoted += | |
| 1305 (int)(CompactibleFreeListSpace::adjustObjectSize(obj->size())); | |
| 1306 ) | |
| 1307 } | |
| 1308 return res; | |
| 1309 } | |
| 1310 | |
| 1311 | |
| 1312 HeapWord* | |
| 1313 ConcurrentMarkSweepGeneration::allocation_limit_reached(Space* space, | |
| 1314 HeapWord* top, | |
| 1315 size_t word_sz) | |
| 1316 { | |
| 1317 return collector()->allocation_limit_reached(space, top, word_sz); | |
| 1318 } | |
| 1319 | |
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1320 // IMPORTANT: Notes on object size recognition in CMS. |
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1321 // --------------------------------------------------- |
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1322 // A block of storage in the CMS generation is always in |
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1323 // one of three states. A free block (FREE), an allocated |
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1324 // object (OBJECT) whose size() method reports the correct size, |
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1325 // and an intermediate state (TRANSIENT) in which its size cannot |
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1326 // be accurately determined. |
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1327 // STATE IDENTIFICATION: (32 bit and 64 bit w/o COOPS) |
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1328 // ----------------------------------------------------- |
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1329 // FREE: klass_word & 1 == 1; mark_word holds block size |
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1330 // |
|
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1331 // OBJECT: klass_word installed; klass_word != 0 && klass_word & 1 == 0; |
|
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1332 // obj->size() computes correct size |
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1333 // |
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1334 // TRANSIENT: klass_word == 0; size is indeterminate until we become an OBJECT |
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1335 // |
|
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1336 // STATE IDENTIFICATION: (64 bit+COOPS) |
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1337 // ------------------------------------ |
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1338 // FREE: mark_word & CMS_FREE_BIT == 1; mark_word & ~CMS_FREE_BIT gives block_size |
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1339 // |
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1340 // OBJECT: klass_word installed; klass_word != 0; |
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1341 // obj->size() computes correct size |
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1342 // |
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1343 // TRANSIENT: klass_word == 0; size is indeterminate until we become an OBJECT |
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1344 // |
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1345 // |
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1346 // STATE TRANSITION DIAGRAM |
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1347 // |
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1348 // mut / parnew mut / parnew |
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1349 // FREE --------------------> TRANSIENT ---------------------> OBJECT --| |
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1350 // ^ | |
|
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1351 // |------------------------ DEAD <------------------------------------| |
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1352 // sweep mut |
|
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1353 // |
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1354 // While a block is in TRANSIENT state its size cannot be determined |
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1355 // so readers will either need to come back later or stall until |
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1356 // the size can be determined. Note that for the case of direct |
|
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1357 // allocation, P-bits, when available, may be used to determine the |
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1358 // size of an object that may not yet have been initialized. |
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1359 |
| 0 | 1360 // Things to support parallel young-gen collection. |
| 1361 oop | |
| 1362 ConcurrentMarkSweepGeneration::par_promote(int thread_num, | |
| 1363 oop old, markOop m, | |
| 1364 size_t word_sz) { | |
| 1365 #ifndef PRODUCT | |
| 1366 if (Universe::heap()->promotion_should_fail()) { | |
| 1367 return NULL; | |
| 1368 } | |
| 1369 #endif // #ifndef PRODUCT | |
| 1370 | |
| 1371 CMSParGCThreadState* ps = _par_gc_thread_states[thread_num]; | |
| 1372 PromotionInfo* promoInfo = &ps->promo; | |
| 1373 // if we are tracking promotions, then first ensure space for | |
| 1374 // promotion (including spooling space for saving header if necessary). | |
| 1375 // then allocate and copy, then track promoted info if needed. | |
| 1376 // When tracking (see PromotionInfo::track()), the mark word may | |
| 1377 // be displaced and in this case restoration of the mark word | |
| 1378 // occurs in the (oop_since_save_marks_)iterate phase. | |
| 1379 if (promoInfo->tracking() && !promoInfo->ensure_spooling_space()) { | |
| 1380 // Out of space for allocating spooling buffers; | |
| 1381 // try expanding and allocating spooling buffers. | |
| 1382 if (!expand_and_ensure_spooling_space(promoInfo)) { | |
| 1383 return NULL; | |
| 1384 } | |
| 1385 } | |
| 1386 assert(promoInfo->has_spooling_space(), "Control point invariant"); | |
|
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1387 const size_t alloc_sz = CompactibleFreeListSpace::adjustObjectSize(word_sz); |
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1388 HeapWord* obj_ptr = ps->lab.alloc(alloc_sz); |
| 0 | 1389 if (obj_ptr == NULL) { |
|
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1390 obj_ptr = expand_and_par_lab_allocate(ps, alloc_sz); |
| 0 | 1391 if (obj_ptr == NULL) { |
| 1392 return NULL; | |
| 1393 } | |
| 1394 } | |
| 1395 oop obj = oop(obj_ptr); | |
|
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1396 OrderAccess::storestore(); |
| 187 | 1397 assert(obj->klass_or_null() == NULL, "Object should be uninitialized here."); |
|
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1398 assert(!((FreeChunk*)obj_ptr)->is_free(), "Error, block will look free but show wrong size"); |
|
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1399 // IMPORTANT: See note on object initialization for CMS above. |
| 0 | 1400 // Otherwise, copy the object. Here we must be careful to insert the |
| 1401 // klass pointer last, since this marks the block as an allocated object. | |
| 187 | 1402 // Except with compressed oops it's the mark word. |
| 0 | 1403 HeapWord* old_ptr = (HeapWord*)old; |
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1404 // Restore the mark word copied above. |
|
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1405 obj->set_mark(m); |
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1406 assert(obj->klass_or_null() == NULL, "Object should be uninitialized here."); |
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1407 assert(!((FreeChunk*)obj_ptr)->is_free(), "Error, block will look free but show wrong size"); |
|
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1408 OrderAccess::storestore(); |
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1409 |
|
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1410 if (UseCompressedClassPointers) { |
|
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1411 // Copy gap missed by (aligned) header size calculation below |
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1412 obj->set_klass_gap(old->klass_gap()); |
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1413 } |
| 0 | 1414 if (word_sz > (size_t)oopDesc::header_size()) { |
| 1415 Copy::aligned_disjoint_words(old_ptr + oopDesc::header_size(), | |
| 1416 obj_ptr + oopDesc::header_size(), | |
| 1417 word_sz - oopDesc::header_size()); | |
| 1418 } | |
| 187 | 1419 |
| 0 | 1420 // Now we can track the promoted object, if necessary. We take care |
| 1521 | 1421 // to delay the transition from uninitialized to full object |
| 0 | 1422 // (i.e., insertion of klass pointer) until after, so that it |
| 1423 // atomically becomes a promoted object. | |
| 1424 if (promoInfo->tracking()) { | |
| 1425 promoInfo->track((PromotedObject*)obj, old->klass()); | |
| 1426 } | |
|
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1427 assert(obj->klass_or_null() == NULL, "Object should be uninitialized here."); |
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1428 assert(!((FreeChunk*)obj_ptr)->is_free(), "Error, block will look free but show wrong size"); |
|
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1429 assert(old->is_oop(), "Will use and dereference old klass ptr below"); |
| 187 | 1430 |
| 1431 // Finally, install the klass pointer (this should be volatile). | |
|
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1432 OrderAccess::storestore(); |
| 0 | 1433 obj->set_klass(old->klass()); |
|
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1434 // We should now be able to calculate the right size for this object |
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1435 assert(obj->is_oop() && obj->size() == (int)word_sz, "Error, incorrect size computed for promoted object"); |
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1436 |
| 0 | 1437 collector()->promoted(true, // parallel |
| 1438 obj_ptr, old->is_objArray(), word_sz); | |
| 1439 | |
| 1440 NOT_PRODUCT( | |
|
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1441 Atomic::inc_ptr(&_numObjectsPromoted); |
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1442 Atomic::add_ptr(alloc_sz, &_numWordsPromoted); |
| 0 | 1443 ) |
| 1444 | |
| 1445 return obj; | |
| 1446 } | |
| 1447 | |
| 1448 void | |
| 1449 ConcurrentMarkSweepGeneration:: | |
| 1450 par_promote_alloc_undo(int thread_num, | |
| 1451 HeapWord* obj, size_t word_sz) { | |
| 1452 // CMS does not support promotion undo. | |
| 1453 ShouldNotReachHere(); | |
| 1454 } | |
| 1455 | |
| 1456 void | |
| 1457 ConcurrentMarkSweepGeneration:: | |
| 1458 par_promote_alloc_done(int thread_num) { | |
| 1459 CMSParGCThreadState* ps = _par_gc_thread_states[thread_num]; | |
|
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1460 ps->lab.retire(thread_num); |
| 0 | 1461 } |
| 1462 | |
| 1463 void | |
| 1464 ConcurrentMarkSweepGeneration:: | |
| 1465 par_oop_since_save_marks_iterate_done(int thread_num) { | |
| 1466 CMSParGCThreadState* ps = _par_gc_thread_states[thread_num]; | |
| 1467 ParScanWithoutBarrierClosure* dummy_cl = NULL; | |
| 1468 ps->promo.promoted_oops_iterate_nv(dummy_cl); | |
| 1469 } | |
| 1470 | |
| 1471 bool ConcurrentMarkSweepGeneration::should_collect(bool full, | |
| 1472 size_t size, | |
| 1473 bool tlab) | |
| 1474 { | |
| 1475 // We allow a STW collection only if a full | |
| 1476 // collection was requested. | |
| 1477 return full || should_allocate(size, tlab); // FIX ME !!! | |
| 1478 // This and promotion failure handling are connected at the | |
| 1479 // hip and should be fixed by untying them. | |
| 1480 } | |
| 1481 | |
| 1482 bool CMSCollector::shouldConcurrentCollect() { | |
| 1483 if (_full_gc_requested) { | |
| 1484 if (Verbose && PrintGCDetails) { | |
| 1485 gclog_or_tty->print_cr("CMSCollector: collect because of explicit " | |
|
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1486 " gc request (or gc_locker)"); |
| 0 | 1487 } |
| 1488 return true; | |
| 1489 } | |
| 1490 | |
| 1491 // For debugging purposes, change the type of collection. | |
| 1492 // If the rotation is not on the concurrent collection | |
| 1493 // type, don't start a concurrent collection. | |
| 1494 NOT_PRODUCT( | |
| 1495 if (RotateCMSCollectionTypes && | |
| 1496 (_cmsGen->debug_collection_type() != | |
| 1497 ConcurrentMarkSweepGeneration::Concurrent_collection_type)) { | |
| 1498 assert(_cmsGen->debug_collection_type() != | |
| 1499 ConcurrentMarkSweepGeneration::Unknown_collection_type, | |
| 1500 "Bad cms collection type"); | |
| 1501 return false; | |
| 1502 } | |
| 1503 ) | |
| 1504 | |
| 1505 FreelistLocker x(this); | |
| 1506 // ------------------------------------------------------------------ | |
| 1507 // Print out lots of information which affects the initiation of | |
| 1508 // a collection. | |
| 1509 if (PrintCMSInitiationStatistics && stats().valid()) { | |
| 1510 gclog_or_tty->print("CMSCollector shouldConcurrentCollect: "); | |
| 1511 gclog_or_tty->stamp(); | |
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1512 gclog_or_tty->cr(); |
| 0 | 1513 stats().print_on(gclog_or_tty); |
| 1514 gclog_or_tty->print_cr("time_until_cms_gen_full %3.7f", | |
| 1515 stats().time_until_cms_gen_full()); | |
| 1516 gclog_or_tty->print_cr("free="SIZE_FORMAT, _cmsGen->free()); | |
| 1517 gclog_or_tty->print_cr("contiguous_available="SIZE_FORMAT, | |
| 1518 _cmsGen->contiguous_available()); | |
| 1519 gclog_or_tty->print_cr("promotion_rate=%g", stats().promotion_rate()); | |
| 1520 gclog_or_tty->print_cr("cms_allocation_rate=%g", stats().cms_allocation_rate()); | |
| 1521 gclog_or_tty->print_cr("occupancy=%3.7f", _cmsGen->occupancy()); | |
|
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1522 gclog_or_tty->print_cr("initiatingOccupancy=%3.7f", _cmsGen->initiating_occupancy()); |
|
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1523 gclog_or_tty->print_cr("cms_time_since_begin=%3.7f", stats().cms_time_since_begin()); |
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1524 gclog_or_tty->print_cr("cms_time_since_end=%3.7f", stats().cms_time_since_end()); |
|
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1525 gclog_or_tty->print_cr("metadata initialized %d", |
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1526 MetaspaceGC::should_concurrent_collect()); |
| 0 | 1527 } |
| 1528 // ------------------------------------------------------------------ | |
| 1529 | |
| 1530 // If the estimated time to complete a cms collection (cms_duration()) | |
| 1531 // is less than the estimated time remaining until the cms generation | |
| 1532 // is full, start a collection. | |
| 1533 if (!UseCMSInitiatingOccupancyOnly) { | |
| 1534 if (stats().valid()) { | |
| 1535 if (stats().time_until_cms_start() == 0.0) { | |
| 1536 return true; | |
| 1537 } | |
| 1538 } else { | |
| 1539 // We want to conservatively collect somewhat early in order | |
| 1540 // to try and "bootstrap" our CMS/promotion statistics; | |
| 1541 // this branch will not fire after the first successful CMS | |
| 1542 // collection because the stats should then be valid. | |
| 1543 if (_cmsGen->occupancy() >= _bootstrap_occupancy) { | |
| 1544 if (Verbose && PrintGCDetails) { | |
| 1545 gclog_or_tty->print_cr( | |
| 1546 " CMSCollector: collect for bootstrapping statistics:" | |
| 1547 " occupancy = %f, boot occupancy = %f", _cmsGen->occupancy(), | |
| 1548 _bootstrap_occupancy); | |
| 1549 } | |
| 1550 return true; | |
| 1551 } | |
| 1552 } | |
| 1553 } | |
| 1554 | |
|
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1555 // Otherwise, we start a collection cycle if |
| 0 | 1556 // old gen want a collection cycle started. Each may use |
| 1557 // an appropriate criterion for making this decision. | |
| 1558 // XXX We need to make sure that the gen expansion | |
|
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1559 // criterion dovetails well with this. XXX NEED TO FIX THIS |
|
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1560 if (_cmsGen->should_concurrent_collect()) { |
| 0 | 1561 if (Verbose && PrintGCDetails) { |
| 1562 gclog_or_tty->print_cr("CMS old gen initiated"); | |
| 1563 } | |
| 1564 return true; | |
| 1565 } | |
| 1566 | |
|
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1567 // We start a collection if we believe an incremental collection may fail; |
|
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1568 // this is not likely to be productive in practice because it's probably too |
|
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1569 // late anyway. |
|
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1570 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
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1571 assert(gch->collector_policy()->is_two_generation_policy(), |
|
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1572 "You may want to check the correctness of the following"); |
|
1994
6cd6d394f280
7001033: assert(gch->gc_cause() == GCCause::_scavenge_alot || !gch->incremental_collection_failed())
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1573 if (gch->incremental_collection_will_fail(true /* consult_young */)) { |
|
6cd6d394f280
7001033: assert(gch->gc_cause() == GCCause::_scavenge_alot || !gch->incremental_collection_failed())
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1574 if (Verbose && PrintGCDetails) { |
|
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1575 gclog_or_tty->print("CMSCollector: collect because incremental collection will fail "); |
| 0 | 1576 } |
| 1577 return true; | |
| 1578 } | |
| 1579 | |
|
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1580 if (MetaspaceGC::should_concurrent_collect()) { |
|
20278
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1581 if (Verbose && PrintGCDetails) { |
|
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1582 gclog_or_tty->print("CMSCollector: collect for metadata allocation "); |
|
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1583 } |
|
2c6ef90f030a
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1584 return true; |
|
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1585 } |
|
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1586 |
|
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1587 // CMSTriggerInterval starts a CMS cycle if enough time has passed. |
|
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1588 if (CMSTriggerInterval >= 0) { |
|
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1589 if (CMSTriggerInterval == 0) { |
|
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1590 // Trigger always |
|
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1591 return true; |
|
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1592 } |
|
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1593 |
|
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1594 // Check the CMS time since begin (we do not check the stats validity |
|
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1595 // as we want to be able to trigger the first CMS cycle as well) |
|
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1596 if (stats().cms_time_since_begin() >= (CMSTriggerInterval / ((double) MILLIUNITS))) { |
|
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1597 if (Verbose && PrintGCDetails) { |
|
20326
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1598 if (stats().valid()) { |
|
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1599 gclog_or_tty->print_cr("CMSCollector: collect because of trigger interval (time since last begin %3.7f secs)", |
|
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1600 stats().cms_time_since_begin()); |
|
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1601 } else { |
|
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1602 gclog_or_tty->print_cr("CMSCollector: collect because of trigger interval (first collection)"); |
|
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1603 } |
|
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1604 } |
|
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1605 return true; |
|
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1606 } |
|
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1607 } |
|
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1608 |
| 0 | 1609 return false; |
| 1610 } | |
| 1611 | |
|
10244
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1612 void CMSCollector::set_did_compact(bool v) { _cmsGen->set_did_compact(v); } |
|
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1613 |
| 0 | 1614 // Clear _expansion_cause fields of constituent generations |
| 1615 void CMSCollector::clear_expansion_cause() { | |
| 1616 _cmsGen->clear_expansion_cause(); | |
| 1617 } | |
| 1618 | |
|
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1619 // We should be conservative in starting a collection cycle. To |
|
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1620 // start too eagerly runs the risk of collecting too often in the |
|
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|
1621 // extreme. To collect too rarely falls back on full collections, |
|
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1622 // which works, even if not optimum in terms of concurrent work. |
|
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1623 // As a work around for too eagerly collecting, use the flag |
|
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1624 // UseCMSInitiatingOccupancyOnly. This also has the advantage of |
|
0834225a7916
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|
1625 // giving the user an easily understandable way of controlling the |
|
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1626 // collections. |
|
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1627 // We want to start a new collection cycle if any of the following |
|
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1628 // conditions hold: |
|
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1629 // . our current occupancy exceeds the configured initiating occupancy |
|
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1630 // for this generation, or |
|
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1631 // . we recently needed to expand this space and have not, since that |
|
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|
1632 // expansion, done a collection of this generation, or |
|
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1633 // . the underlying space believes that it may be a good idea to initiate |
|
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|
1634 // a concurrent collection (this may be based on criteria such as the |
|
0834225a7916
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|
1635 // following: the space uses linear allocation and linear allocation is |
|
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|
1636 // going to fail, or there is believed to be excessive fragmentation in |
|
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1637 // the generation, etc... or ... |
|
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1638 // [.(currently done by CMSCollector::shouldConcurrentCollect() only for |
|
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1639 // the case of the old generation; see CR 6543076): |
|
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1640 // we may be approaching a point at which allocation requests may fail because |
|
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|
1641 // we will be out of sufficient free space given allocation rate estimates.] |
|
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|
1642 bool ConcurrentMarkSweepGeneration::should_concurrent_collect() const { |
|
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|
1643 |
| 0 | 1644 assert_lock_strong(freelistLock()); |
|
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|
1645 if (occupancy() > initiating_occupancy()) { |
| 0 | 1646 if (PrintGCDetails && Verbose) { |
| 1647 gclog_or_tty->print(" %s: collect because of occupancy %f / %f ", | |
|
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|
1648 short_name(), occupancy(), initiating_occupancy()); |
| 0 | 1649 } |
| 1650 return true; | |
| 1651 } | |
| 1652 if (UseCMSInitiatingOccupancyOnly) { | |
| 1653 return false; | |
| 1654 } | |
| 1655 if (expansion_cause() == CMSExpansionCause::_satisfy_allocation) { | |
| 1656 if (PrintGCDetails && Verbose) { | |
| 1657 gclog_or_tty->print(" %s: collect because expanded for allocation ", | |
| 1658 short_name()); | |
| 1659 } | |
| 1660 return true; | |
| 1661 } | |
|
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|
1662 if (_cmsSpace->should_concurrent_collect()) { |
| 0 | 1663 if (PrintGCDetails && Verbose) { |
|
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|
1664 gclog_or_tty->print(" %s: collect because cmsSpace says so ", |
| 0 | 1665 short_name()); |
| 1666 } | |
| 1667 return true; | |
| 1668 } | |
| 1669 return false; | |
| 1670 } | |
| 1671 | |
| 1672 void ConcurrentMarkSweepGeneration::collect(bool full, | |
| 1673 bool clear_all_soft_refs, | |
| 1674 size_t size, | |
| 1675 bool tlab) | |
| 1676 { | |
| 1677 collector()->collect(full, clear_all_soft_refs, size, tlab); | |
| 1678 } | |
| 1679 | |
| 1680 void CMSCollector::collect(bool full, | |
| 1681 bool clear_all_soft_refs, | |
| 1682 size_t size, | |
| 1683 bool tlab) | |
| 1684 { | |
| 1685 if (!UseCMSCollectionPassing && _collectorState > Idling) { | |
| 1686 // For debugging purposes skip the collection if the state | |
| 1687 // is not currently idle | |
| 1688 if (TraceCMSState) { | |
| 1689 gclog_or_tty->print_cr("Thread " INTPTR_FORMAT " skipped full:%d CMS state %d", | |
| 1690 Thread::current(), full, _collectorState); | |
| 1691 } | |
| 1692 return; | |
| 1693 } | |
| 1694 | |
| 1695 // The following "if" branch is present for defensive reasons. | |
| 1696 // In the current uses of this interface, it can be replaced with: | |
| 1697 // assert(!GC_locker.is_active(), "Can't be called otherwise"); | |
| 1698 // But I am not placing that assert here to allow future | |
| 1699 // generality in invoking this interface. | |
| 1700 if (GC_locker::is_active()) { | |
| 1701 // A consistency test for GC_locker | |
| 1702 assert(GC_locker::needs_gc(), "Should have been set already"); | |
| 1703 // Skip this foreground collection, instead | |
| 1704 // expanding the heap if necessary. | |
| 1705 // Need the free list locks for the call to free() in compute_new_size() | |
| 1706 compute_new_size(); | |
| 1707 return; | |
| 1708 } | |
| 1709 acquire_control_and_collect(full, clear_all_soft_refs); | |
| 1710 _full_gcs_since_conc_gc++; | |
| 1711 } | |
| 1712 | |
| 10405 | 1713 void CMSCollector::request_full_gc(unsigned int full_gc_count, GCCause::Cause cause) { |
| 0 | 1714 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
| 1715 unsigned int gc_count = gch->total_full_collections(); | |
| 1716 if (gc_count == full_gc_count) { | |
| 1717 MutexLockerEx y(CGC_lock, Mutex::_no_safepoint_check_flag); | |
| 1718 _full_gc_requested = true; | |
| 10405 | 1719 _full_gc_cause = cause; |
| 0 | 1720 CGC_lock->notify(); // nudge CMS thread |
|
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1721 } else { |
|
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|
1722 assert(gc_count > full_gc_count, "Error: causal loop"); |
| 0 | 1723 } |
| 1724 } | |
| 1725 | |
| 10405 | 1726 bool CMSCollector::is_external_interruption() { |
| 1727 GCCause::Cause cause = GenCollectedHeap::heap()->gc_cause(); | |
| 1728 return GCCause::is_user_requested_gc(cause) || | |
| 1729 GCCause::is_serviceability_requested_gc(cause); | |
| 1730 } | |
| 1731 | |
| 1732 void CMSCollector::report_concurrent_mode_interruption() { | |
| 1733 if (is_external_interruption()) { | |
| 1734 if (PrintGCDetails) { | |
| 1735 gclog_or_tty->print(" (concurrent mode interrupted)"); | |
| 1736 } | |
| 1737 } else { | |
| 1738 if (PrintGCDetails) { | |
| 1739 gclog_or_tty->print(" (concurrent mode failure)"); | |
| 1740 } | |
| 1741 _gc_tracer_cm->report_concurrent_mode_failure(); | |
| 1742 } | |
| 1743 } | |
| 1744 | |
| 0 | 1745 |
| 1746 // The foreground and background collectors need to coordinate in order | |
| 1747 // to make sure that they do not mutually interfere with CMS collections. | |
| 1748 // When a background collection is active, | |
| 1749 // the foreground collector may need to take over (preempt) and | |
| 1750 // synchronously complete an ongoing collection. Depending on the | |
| 1751 // frequency of the background collections and the heap usage | |
| 1752 // of the application, this preemption can be seldom or frequent. | |
| 1753 // There are only certain | |
| 1754 // points in the background collection that the "collection-baton" | |
| 1755 // can be passed to the foreground collector. | |
| 1756 // | |
| 1757 // The foreground collector will wait for the baton before | |
| 1758 // starting any part of the collection. The foreground collector | |
| 1759 // will only wait at one location. | |
| 1760 // | |
| 1761 // The background collector will yield the baton before starting a new | |
| 1762 // phase of the collection (e.g., before initial marking, marking from roots, | |
| 1763 // precleaning, final re-mark, sweep etc.) This is normally done at the head | |
| 1764 // of the loop which switches the phases. The background collector does some | |
| 1765 // of the phases (initial mark, final re-mark) with the world stopped. | |
| 1766 // Because of locking involved in stopping the world, | |
| 1767 // the foreground collector should not block waiting for the background | |
| 1768 // collector when it is doing a stop-the-world phase. The background | |
| 1769 // collector will yield the baton at an additional point just before | |
| 1770 // it enters a stop-the-world phase. Once the world is stopped, the | |
| 1771 // background collector checks the phase of the collection. If the | |
| 1772 // phase has not changed, it proceeds with the collection. If the | |
| 1773 // phase has changed, it skips that phase of the collection. See | |
| 1774 // the comments on the use of the Heap_lock in collect_in_background(). | |
| 1775 // | |
| 1776 // Variable used in baton passing. | |
| 1777 // _foregroundGCIsActive - Set to true by the foreground collector when | |
| 1778 // it wants the baton. The foreground clears it when it has finished | |
| 1779 // the collection. | |
| 1780 // _foregroundGCShouldWait - Set to true by the background collector | |
| 1781 // when it is running. The foreground collector waits while | |
| 1782 // _foregroundGCShouldWait is true. | |
| 1783 // CGC_lock - monitor used to protect access to the above variables | |
| 1784 // and to notify the foreground and background collectors. | |
| 1785 // _collectorState - current state of the CMS collection. | |
| 1786 // | |
| 1787 // The foreground collector | |
| 1788 // acquires the CGC_lock | |
| 1789 // sets _foregroundGCIsActive | |
| 1790 // waits on the CGC_lock for _foregroundGCShouldWait to be false | |
| 1791 // various locks acquired in preparation for the collection | |
| 1792 // are released so as not to block the background collector | |
| 1793 // that is in the midst of a collection | |
| 1794 // proceeds with the collection | |
| 1795 // clears _foregroundGCIsActive | |
| 1796 // returns | |
| 1797 // | |
| 1798 // The background collector in a loop iterating on the phases of the | |
| 1799 // collection | |
| 1800 // acquires the CGC_lock | |
| 1801 // sets _foregroundGCShouldWait | |
| 1802 // if _foregroundGCIsActive is set | |
| 1803 // clears _foregroundGCShouldWait, notifies _CGC_lock | |
| 1804 // waits on _CGC_lock for _foregroundGCIsActive to become false | |
| 1805 // and exits the loop. | |
| 1806 // otherwise | |
| 1807 // proceed with that phase of the collection | |
| 1808 // if the phase is a stop-the-world phase, | |
| 1809 // yield the baton once more just before enqueueing | |
| 1810 // the stop-world CMS operation (executed by the VM thread). | |
| 1811 // returns after all phases of the collection are done | |
| 1812 // | |
| 1813 | |
| 1814 void CMSCollector::acquire_control_and_collect(bool full, | |
| 1815 bool clear_all_soft_refs) { | |
| 1816 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); | |
| 1817 assert(!Thread::current()->is_ConcurrentGC_thread(), | |
| 1818 "shouldn't try to acquire control from self!"); | |
| 1819 | |
| 1820 // Start the protocol for acquiring control of the | |
| 1821 // collection from the background collector (aka CMS thread). | |
| 1822 assert(ConcurrentMarkSweepThread::vm_thread_has_cms_token(), | |
| 1823 "VM thread should have CMS token"); | |
| 1824 // Remember the possibly interrupted state of an ongoing | |
| 1825 // concurrent collection | |
| 1826 CollectorState first_state = _collectorState; | |
| 1827 | |
| 1828 // Signal to a possibly ongoing concurrent collection that | |
| 1829 // we want to do a foreground collection. | |
| 1830 _foregroundGCIsActive = true; | |
| 1831 | |
| 1832 // Disable incremental mode during a foreground collection. | |
| 1833 ICMSDisabler icms_disabler; | |
| 1834 | |
| 1835 // release locks and wait for a notify from the background collector | |
| 1836 // releasing the locks in only necessary for phases which | |
| 1837 // do yields to improve the granularity of the collection. | |
| 1838 assert_lock_strong(bitMapLock()); | |
| 1839 // We need to lock the Free list lock for the space that we are | |
| 1840 // currently collecting. | |
| 1841 assert(haveFreelistLocks(), "Must be holding free list locks"); | |
| 1842 bitMapLock()->unlock(); | |
| 1843 releaseFreelistLocks(); | |
| 1844 { | |
| 1845 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
| 1846 if (_foregroundGCShouldWait) { | |
| 1847 // We are going to be waiting for action for the CMS thread; | |
| 1848 // it had better not be gone (for instance at shutdown)! | |
| 1849 assert(ConcurrentMarkSweepThread::cmst() != NULL, | |
| 1850 "CMS thread must be running"); | |
| 1851 // Wait here until the background collector gives us the go-ahead | |
| 1852 ConcurrentMarkSweepThread::clear_CMS_flag( | |
| 1853 ConcurrentMarkSweepThread::CMS_vm_has_token); // release token | |
| 1854 // Get a possibly blocked CMS thread going: | |
| 1855 // Note that we set _foregroundGCIsActive true above, | |
| 1856 // without protection of the CGC_lock. | |
| 1857 CGC_lock->notify(); | |
| 1858 assert(!ConcurrentMarkSweepThread::vm_thread_wants_cms_token(), | |
| 1859 "Possible deadlock"); | |
| 1860 while (_foregroundGCShouldWait) { | |
| 1861 // wait for notification | |
| 1862 CGC_lock->wait(Mutex::_no_safepoint_check_flag); | |
| 1863 // Possibility of delay/starvation here, since CMS token does | |
| 1864 // not know to give priority to VM thread? Actually, i think | |
| 1865 // there wouldn't be any delay/starvation, but the proof of | |
| 1866 // that "fact" (?) appears non-trivial. XXX 20011219YSR | |
| 1867 } | |
| 1868 ConcurrentMarkSweepThread::set_CMS_flag( | |
| 1869 ConcurrentMarkSweepThread::CMS_vm_has_token); | |
| 1870 } | |
| 1871 } | |
| 1872 // The CMS_token is already held. Get back the other locks. | |
| 1873 assert(ConcurrentMarkSweepThread::vm_thread_has_cms_token(), | |
| 1874 "VM thread should have CMS token"); | |
| 1875 getFreelistLocks(); | |
| 1876 bitMapLock()->lock_without_safepoint_check(); | |
| 1877 if (TraceCMSState) { | |
| 1878 gclog_or_tty->print_cr("CMS foreground collector has asked for control " | |
| 1879 INTPTR_FORMAT " with first state %d", Thread::current(), first_state); | |
| 1880 gclog_or_tty->print_cr(" gets control with state %d", _collectorState); | |
| 1881 } | |
| 1882 | |
| 1883 // Check if we need to do a compaction, or if not, whether | |
| 1884 // we need to start the mark-sweep from scratch. | |
| 1885 bool should_compact = false; | |
| 1886 bool should_start_over = false; | |
| 1887 decide_foreground_collection_type(clear_all_soft_refs, | |
| 1888 &should_compact, &should_start_over); | |
| 1889 | |
| 1890 NOT_PRODUCT( | |
| 1891 if (RotateCMSCollectionTypes) { | |
| 1892 if (_cmsGen->debug_collection_type() == | |
| 1893 ConcurrentMarkSweepGeneration::MSC_foreground_collection_type) { | |
| 1894 should_compact = true; | |
| 1895 } else if (_cmsGen->debug_collection_type() == | |
| 1896 ConcurrentMarkSweepGeneration::MS_foreground_collection_type) { | |
| 1897 should_compact = false; | |
| 1898 } | |
| 1899 } | |
| 1900 ) | |
| 1901 | |
| 10405 | 1902 if (first_state > Idling) { |
| 1903 report_concurrent_mode_interruption(); | |
| 0 | 1904 } |
| 1905 | |
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1906 set_did_compact(should_compact); |
| 0 | 1907 if (should_compact) { |
| 1908 // If the collection is being acquired from the background | |
| 1909 // collector, there may be references on the discovered | |
| 1910 // references lists that have NULL referents (being those | |
| 1911 // that were concurrently cleared by a mutator) or | |
| 1912 // that are no longer active (having been enqueued concurrently | |
| 1913 // by the mutator). | |
| 1914 // Scrub the list of those references because Mark-Sweep-Compact | |
| 1915 // code assumes referents are not NULL and that all discovered | |
| 1916 // Reference objects are active. | |
| 1917 ref_processor()->clean_up_discovered_references(); | |
| 1918 | |
| 10405 | 1919 if (first_state > Idling) { |
| 1920 save_heap_summary(); | |
| 1921 } | |
| 1922 | |
| 0 | 1923 do_compaction_work(clear_all_soft_refs); |
| 1924 | |
| 1925 // Has the GC time limit been exceeded? | |
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1926 DefNewGeneration* young_gen = _young_gen->as_DefNewGeneration(); |
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1927 size_t max_eden_size = young_gen->max_capacity() - |
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1928 young_gen->to()->capacity() - |
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1929 young_gen->from()->capacity(); |
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1930 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
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1931 GCCause::Cause gc_cause = gch->gc_cause(); |
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1932 size_policy()->check_gc_overhead_limit(_young_gen->used(), |
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1933 young_gen->eden()->used(), |
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1934 _cmsGen->max_capacity(), |
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1935 max_eden_size, |
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1936 full, |
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1937 gc_cause, |
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1938 gch->collector_policy()); |
| 0 | 1939 } else { |
| 1940 do_mark_sweep_work(clear_all_soft_refs, first_state, | |
| 1941 should_start_over); | |
| 1942 } | |
| 1943 // Reset the expansion cause, now that we just completed | |
| 1944 // a collection cycle. | |
| 1945 clear_expansion_cause(); | |
| 1946 _foregroundGCIsActive = false; | |
| 1947 return; | |
| 1948 } | |
| 1949 | |
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1950 // Resize the tenured generation |
| 0 | 1951 // after obtaining the free list locks for the |
| 1952 // two generations. | |
| 1953 void CMSCollector::compute_new_size() { | |
| 1954 assert_locked_or_safepoint(Heap_lock); | |
| 1955 FreelistLocker z(this); | |
|
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1956 MetaspaceGC::compute_new_size(); |
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1957 _cmsGen->compute_new_size_free_list(); |
| 0 | 1958 } |
| 1959 | |
| 1960 // A work method used by foreground collection to determine | |
| 1961 // what type of collection (compacting or not, continuing or fresh) | |
| 1962 // it should do. | |
| 1963 // NOTE: the intent is to make UseCMSCompactAtFullCollection | |
| 1964 // and CMSCompactWhenClearAllSoftRefs the default in the future | |
| 1965 // and do away with the flags after a suitable period. | |
| 1966 void CMSCollector::decide_foreground_collection_type( | |
| 1967 bool clear_all_soft_refs, bool* should_compact, | |
| 1968 bool* should_start_over) { | |
| 1969 // Normally, we'll compact only if the UseCMSCompactAtFullCollection | |
| 1970 // flag is set, and we have either requested a System.gc() or | |
| 1971 // the number of full gc's since the last concurrent cycle | |
| 1972 // has exceeded the threshold set by CMSFullGCsBeforeCompaction, | |
| 1973 // or if an incremental collection has failed | |
| 1974 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 1975 assert(gch->collector_policy()->is_two_generation_policy(), | |
| 1976 "You may want to check the correctness of the following"); | |
| 1977 // Inform cms gen if this was due to partial collection failing. | |
| 1978 // The CMS gen may use this fact to determine its expansion policy. | |
|
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1979 if (gch->incremental_collection_will_fail(false /* don't consult_young */)) { |
| 0 | 1980 assert(!_cmsGen->incremental_collection_failed(), |
| 1981 "Should have been noticed, reacted to and cleared"); | |
| 1982 _cmsGen->set_incremental_collection_failed(); | |
| 1983 } | |
| 1984 *should_compact = | |
| 1985 UseCMSCompactAtFullCollection && | |
| 1986 ((_full_gcs_since_conc_gc >= CMSFullGCsBeforeCompaction) || | |
| 1987 GCCause::is_user_requested_gc(gch->gc_cause()) || | |
|
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1988 gch->incremental_collection_will_fail(true /* consult_young */)); |
| 0 | 1989 *should_start_over = false; |
| 1990 if (clear_all_soft_refs && !*should_compact) { | |
| 1991 // We are about to do a last ditch collection attempt | |
| 1992 // so it would normally make sense to do a compaction | |
| 1993 // to reclaim as much space as possible. | |
| 1994 if (CMSCompactWhenClearAllSoftRefs) { | |
| 1995 // Default: The rationale is that in this case either | |
| 1996 // we are past the final marking phase, in which case | |
| 1997 // we'd have to start over, or so little has been done | |
| 1998 // that there's little point in saving that work. Compaction | |
| 1999 // appears to be the sensible choice in either case. | |
| 2000 *should_compact = true; | |
| 2001 } else { | |
| 2002 // We have been asked to clear all soft refs, but not to | |
| 2003 // compact. Make sure that we aren't past the final checkpoint | |
| 2004 // phase, for that is where we process soft refs. If we are already | |
| 2005 // past that phase, we'll need to redo the refs discovery phase and | |
| 2006 // if necessary clear soft refs that weren't previously | |
| 2007 // cleared. We do so by remembering the phase in which | |
| 2008 // we came in, and if we are past the refs processing | |
| 2009 // phase, we'll choose to just redo the mark-sweep | |
| 2010 // collection from scratch. | |
| 2011 if (_collectorState > FinalMarking) { | |
| 2012 // We are past the refs processing phase; | |
| 2013 // start over and do a fresh synchronous CMS cycle | |
| 2014 _collectorState = Resetting; // skip to reset to start new cycle | |
| 2015 reset(false /* == !asynch */); | |
| 2016 *should_start_over = true; | |
| 2017 } // else we can continue a possibly ongoing current cycle | |
| 2018 } | |
| 2019 } | |
| 2020 } | |
| 2021 | |
| 2022 // A work method used by the foreground collector to do | |
| 2023 // a mark-sweep-compact. | |
| 2024 void CMSCollector::do_compaction_work(bool clear_all_soft_refs) { | |
| 2025 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 10405 | 2026 |
| 2027 STWGCTimer* gc_timer = GenMarkSweep::gc_timer(); | |
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2028 gc_timer->register_gc_start(); |
| 10405 | 2029 |
| 2030 SerialOldTracer* gc_tracer = GenMarkSweep::gc_tracer(); | |
| 2031 gc_tracer->report_gc_start(gch->gc_cause(), gc_timer->gc_start()); | |
| 2032 | |
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2033 GCTraceTime t("CMS:MSC ", PrintGCDetails && Verbose, true, NULL, gc_tracer->gc_id()); |
| 0 | 2034 if (PrintGC && Verbose && !(GCCause::is_user_requested_gc(gch->gc_cause()))) { |
| 2035 gclog_or_tty->print_cr("Compact ConcurrentMarkSweepGeneration after %d " | |
| 2036 "collections passed to foreground collector", _full_gcs_since_conc_gc); | |
| 2037 } | |
| 2038 | |
| 2039 // Sample collection interval time and reset for collection pause. | |
| 2040 if (UseAdaptiveSizePolicy) { | |
| 2041 size_policy()->msc_collection_begin(); | |
| 2042 } | |
| 2043 | |
| 2044 // Temporarily widen the span of the weak reference processing to | |
| 2045 // the entire heap. | |
| 2046 MemRegion new_span(GenCollectedHeap::heap()->reserved_region()); | |
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2047 ReferenceProcessorSpanMutator rp_mut_span(ref_processor(), new_span); |
| 0 | 2048 // Temporarily, clear the "is_alive_non_header" field of the |
| 2049 // reference processor. | |
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2050 ReferenceProcessorIsAliveMutator rp_mut_closure(ref_processor(), NULL); |
| 0 | 2051 // Temporarily make reference _processing_ single threaded (non-MT). |
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2052 ReferenceProcessorMTProcMutator rp_mut_mt_processing(ref_processor(), false); |
| 0 | 2053 // Temporarily make refs discovery atomic |
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2054 ReferenceProcessorAtomicMutator rp_mut_atomic(ref_processor(), true); |
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2055 // Temporarily make reference _discovery_ single threaded (non-MT) |
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2056 ReferenceProcessorMTDiscoveryMutator rp_mut_discovery(ref_processor(), false); |
| 0 | 2057 |
| 2058 ref_processor()->set_enqueuing_is_done(false); | |
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2059 ref_processor()->enable_discovery(false /*verify_disabled*/, false /*check_no_refs*/); |
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2060 ref_processor()->setup_policy(clear_all_soft_refs); |
| 0 | 2061 // If an asynchronous collection finishes, the _modUnionTable is |
| 2062 // all clear. If we are assuming the collection from an asynchronous | |
| 2063 // collection, clear the _modUnionTable. | |
| 2064 assert(_collectorState != Idling || _modUnionTable.isAllClear(), | |
| 2065 "_modUnionTable should be clear if the baton was not passed"); | |
| 2066 _modUnionTable.clear_all(); | |
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2067 assert(_collectorState != Idling || _ct->klass_rem_set()->mod_union_is_clear(), |
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2068 "mod union for klasses should be clear if the baton was passed"); |
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2069 _ct->klass_rem_set()->clear_mod_union(); |
| 0 | 2070 |
| 2071 // We must adjust the allocation statistics being maintained | |
| 2072 // in the free list space. We do so by reading and clearing | |
| 2073 // the sweep timer and updating the block flux rate estimates below. | |
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2074 assert(!_intra_sweep_timer.is_active(), "_intra_sweep_timer should be inactive"); |
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2075 if (_inter_sweep_timer.is_active()) { |
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2076 _inter_sweep_timer.stop(); |
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2077 // Note that we do not use this sample to update the _inter_sweep_estimate. |
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2078 _cmsGen->cmsSpace()->beginSweepFLCensus((float)(_inter_sweep_timer.seconds()), |
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2079 _inter_sweep_estimate.padded_average(), |
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2080 _intra_sweep_estimate.padded_average()); |
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2081 } |
| 0 | 2082 |
| 2083 GenMarkSweep::invoke_at_safepoint(_cmsGen->level(), | |
| 2084 ref_processor(), clear_all_soft_refs); | |
| 2085 #ifdef ASSERT | |
| 2086 CompactibleFreeListSpace* cms_space = _cmsGen->cmsSpace(); | |
| 2087 size_t free_size = cms_space->free(); | |
| 2088 assert(free_size == | |
| 2089 pointer_delta(cms_space->end(), cms_space->compaction_top()) | |
| 2090 * HeapWordSize, | |
| 2091 "All the free space should be compacted into one chunk at top"); | |
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2092 assert(cms_space->dictionary()->total_chunk_size( |
| 0 | 2093 debug_only(cms_space->freelistLock())) == 0 || |
| 2094 cms_space->totalSizeInIndexedFreeLists() == 0, | |
| 2095 "All the free space should be in a single chunk"); | |
| 2096 size_t num = cms_space->totalCount(); | |
| 2097 assert((free_size == 0 && num == 0) || | |
| 2098 (free_size > 0 && (num == 1 || num == 2)), | |
| 2099 "There should be at most 2 free chunks after compaction"); | |
| 2100 #endif // ASSERT | |
| 2101 _collectorState = Resetting; | |
| 2102 assert(_restart_addr == NULL, | |
| 2103 "Should have been NULL'd before baton was passed"); | |
| 2104 reset(false /* == !asynch */); | |
| 2105 _cmsGen->reset_after_compaction(); | |
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2106 _concurrent_cycles_since_last_unload = 0; |
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2107 |
| 0 | 2108 // Clear any data recorded in the PLAB chunk arrays. |
| 2109 if (_survivor_plab_array != NULL) { | |
| 2110 reset_survivor_plab_arrays(); | |
| 2111 } | |
| 2112 | |
| 2113 // Adjust the per-size allocation stats for the next epoch. | |
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2114 _cmsGen->cmsSpace()->endSweepFLCensus(sweep_count() /* fake */); |
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2115 // Restart the "inter sweep timer" for the next epoch. |
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2116 _inter_sweep_timer.reset(); |
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2117 _inter_sweep_timer.start(); |
| 0 | 2118 |
| 2119 // Sample collection pause time and reset for collection interval. | |
| 2120 if (UseAdaptiveSizePolicy) { | |
| 2121 size_policy()->msc_collection_end(gch->gc_cause()); | |
| 2122 } | |
| 2123 | |
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2124 gc_timer->register_gc_end(); |
| 10405 | 2125 |
| 2126 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); | |
| 2127 | |
| 0 | 2128 // For a mark-sweep-compact, compute_new_size() will be called |
| 2129 // in the heap's do_collection() method. | |
| 2130 } | |
| 2131 | |
| 2132 // A work method used by the foreground collector to do | |
| 2133 // a mark-sweep, after taking over from a possibly on-going | |
| 2134 // concurrent mark-sweep collection. | |
| 2135 void CMSCollector::do_mark_sweep_work(bool clear_all_soft_refs, | |
| 2136 CollectorState first_state, bool should_start_over) { | |
| 2137 if (PrintGC && Verbose) { | |
| 2138 gclog_or_tty->print_cr("Pass concurrent collection to foreground " | |
| 2139 "collector with count %d", | |
| 2140 _full_gcs_since_conc_gc); | |
| 2141 } | |
| 2142 switch (_collectorState) { | |
| 2143 case Idling: | |
| 2144 if (first_state == Idling || should_start_over) { | |
| 2145 // The background GC was not active, or should | |
| 2146 // restarted from scratch; start the cycle. | |
| 2147 _collectorState = InitialMarking; | |
| 2148 } | |
| 2149 // If first_state was not Idling, then a background GC | |
| 2150 // was in progress and has now finished. No need to do it | |
| 2151 // again. Leave the state as Idling. | |
| 2152 break; | |
| 2153 case Precleaning: | |
| 2154 // In the foreground case don't do the precleaning since | |
| 2155 // it is not done concurrently and there is extra work | |
| 2156 // required. | |
| 2157 _collectorState = FinalMarking; | |
| 2158 } | |
| 10405 | 2159 collect_in_foreground(clear_all_soft_refs, GenCollectedHeap::heap()->gc_cause()); |
| 0 | 2160 |
| 2161 // For a mark-sweep, compute_new_size() will be called | |
| 2162 // in the heap's do_collection() method. | |
| 2163 } | |
| 2164 | |
| 2165 | |
|
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2166 void CMSCollector::print_eden_and_survivor_chunk_arrays() { |
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2167 DefNewGeneration* dng = _young_gen->as_DefNewGeneration(); |
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2168 EdenSpace* eden_space = dng->eden(); |
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2169 ContiguousSpace* from_space = dng->from(); |
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2170 ContiguousSpace* to_space = dng->to(); |
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2171 // Eden |
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2172 if (_eden_chunk_array != NULL) { |
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2173 gclog_or_tty->print_cr("eden " PTR_FORMAT "-" PTR_FORMAT "-" PTR_FORMAT "(" SIZE_FORMAT ")", |
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2174 eden_space->bottom(), eden_space->top(), |
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2175 eden_space->end(), eden_space->capacity()); |
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2176 gclog_or_tty->print_cr("_eden_chunk_index=" SIZE_FORMAT ", " |
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2177 "_eden_chunk_capacity=" SIZE_FORMAT, |
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2178 _eden_chunk_index, _eden_chunk_capacity); |
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2179 for (size_t i = 0; i < _eden_chunk_index; i++) { |
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2180 gclog_or_tty->print_cr("_eden_chunk_array[" SIZE_FORMAT "]=" PTR_FORMAT, |
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2181 i, _eden_chunk_array[i]); |
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2182 } |
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2183 } |
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2184 // Survivor |
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2185 if (_survivor_chunk_array != NULL) { |
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2186 gclog_or_tty->print_cr("survivor " PTR_FORMAT "-" PTR_FORMAT "-" PTR_FORMAT "(" SIZE_FORMAT ")", |
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2187 from_space->bottom(), from_space->top(), |
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2188 from_space->end(), from_space->capacity()); |
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2189 gclog_or_tty->print_cr("_survivor_chunk_index=" SIZE_FORMAT ", " |
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2190 "_survivor_chunk_capacity=" SIZE_FORMAT, |
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2191 _survivor_chunk_index, _survivor_chunk_capacity); |
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2192 for (size_t i = 0; i < _survivor_chunk_index; i++) { |
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2193 gclog_or_tty->print_cr("_survivor_chunk_array[" SIZE_FORMAT "]=" PTR_FORMAT, |
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2194 i, _survivor_chunk_array[i]); |
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2195 } |
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2196 } |
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2197 } |
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2198 |
| 0 | 2199 void CMSCollector::getFreelistLocks() const { |
| 2200 // Get locks for all free lists in all generations that this | |
| 2201 // collector is responsible for | |
| 2202 _cmsGen->freelistLock()->lock_without_safepoint_check(); | |
| 2203 } | |
| 2204 | |
| 2205 void CMSCollector::releaseFreelistLocks() const { | |
| 2206 // Release locks for all free lists in all generations that this | |
| 2207 // collector is responsible for | |
| 2208 _cmsGen->freelistLock()->unlock(); | |
| 2209 } | |
| 2210 | |
| 2211 bool CMSCollector::haveFreelistLocks() const { | |
| 2212 // Check locks for all free lists in all generations that this | |
| 2213 // collector is responsible for | |
| 2214 assert_lock_strong(_cmsGen->freelistLock()); | |
| 2215 PRODUCT_ONLY(ShouldNotReachHere()); | |
| 2216 return true; | |
| 2217 } | |
| 2218 | |
| 2219 // A utility class that is used by the CMS collector to | |
| 2220 // temporarily "release" the foreground collector from its | |
| 2221 // usual obligation to wait for the background collector to | |
| 2222 // complete an ongoing phase before proceeding. | |
| 2223 class ReleaseForegroundGC: public StackObj { | |
| 2224 private: | |
| 2225 CMSCollector* _c; | |
| 2226 public: | |
| 2227 ReleaseForegroundGC(CMSCollector* c) : _c(c) { | |
| 2228 assert(_c->_foregroundGCShouldWait, "Else should not need to call"); | |
| 2229 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
| 2230 // allow a potentially blocked foreground collector to proceed | |
| 2231 _c->_foregroundGCShouldWait = false; | |
| 2232 if (_c->_foregroundGCIsActive) { | |
| 2233 CGC_lock->notify(); | |
| 2234 } | |
| 2235 assert(!ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 2236 "Possible deadlock"); | |
| 2237 } | |
| 2238 | |
| 2239 ~ReleaseForegroundGC() { | |
| 2240 assert(!_c->_foregroundGCShouldWait, "Usage protocol violation?"); | |
| 2241 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
| 2242 _c->_foregroundGCShouldWait = true; | |
| 2243 } | |
| 2244 }; | |
| 2245 | |
| 2246 // There are separate collect_in_background and collect_in_foreground because of | |
| 2247 // the different locking requirements of the background collector and the | |
| 2248 // foreground collector. There was originally an attempt to share | |
| 2249 // one "collect" method between the background collector and the foreground | |
| 2250 // collector but the if-then-else required made it cleaner to have | |
| 2251 // separate methods. | |
| 10405 | 2252 void CMSCollector::collect_in_background(bool clear_all_soft_refs, GCCause::Cause cause) { |
| 0 | 2253 assert(Thread::current()->is_ConcurrentGC_thread(), |
| 2254 "A CMS asynchronous collection is only allowed on a CMS thread."); | |
| 2255 | |
| 2256 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 2257 { | |
| 2258 bool safepoint_check = Mutex::_no_safepoint_check_flag; | |
| 2259 MutexLockerEx hl(Heap_lock, safepoint_check); | |
|
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2260 FreelistLocker fll(this); |
| 0 | 2261 MutexLockerEx x(CGC_lock, safepoint_check); |
| 2262 if (_foregroundGCIsActive || !UseAsyncConcMarkSweepGC) { | |
| 2263 // The foreground collector is active or we're | |
| 2264 // not using asynchronous collections. Skip this | |
| 2265 // background collection. | |
| 2266 assert(!_foregroundGCShouldWait, "Should be clear"); | |
| 2267 return; | |
| 2268 } else { | |
| 2269 assert(_collectorState == Idling, "Should be idling before start."); | |
| 2270 _collectorState = InitialMarking; | |
| 10405 | 2271 register_gc_start(cause); |
| 0 | 2272 // Reset the expansion cause, now that we are about to begin |
| 2273 // a new cycle. | |
| 2274 clear_expansion_cause(); | |
|
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2275 |
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2276 // Clear the MetaspaceGC flag since a concurrent collection |
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2277 // is starting but also clear it after the collection. |
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2278 MetaspaceGC::set_should_concurrent_collect(false); |
| 0 | 2279 } |
|
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2280 // Decide if we want to enable class unloading as part of the |
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2281 // ensuing concurrent GC cycle. |
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2282 update_should_unload_classes(); |
| 0 | 2283 _full_gc_requested = false; // acks all outstanding full gc requests |
| 10405 | 2284 _full_gc_cause = GCCause::_no_gc; |
| 0 | 2285 // Signal that we are about to start a collection |
| 2286 gch->increment_total_full_collections(); // ... starting a collection cycle | |
| 2287 _collection_count_start = gch->total_full_collections(); | |
| 2288 } | |
| 2289 | |
| 2290 // Used for PrintGC | |
| 2291 size_t prev_used; | |
| 2292 if (PrintGC && Verbose) { | |
| 2293 prev_used = _cmsGen->used(); // XXXPERM | |
| 2294 } | |
| 2295 | |
| 2296 // The change of the collection state is normally done at this level; | |
| 2297 // the exceptions are phases that are executed while the world is | |
| 2298 // stopped. For those phases the change of state is done while the | |
| 2299 // world is stopped. For baton passing purposes this allows the | |
| 2300 // background collector to finish the phase and change state atomically. | |
| 2301 // The foreground collector cannot wait on a phase that is done | |
| 2302 // while the world is stopped because the foreground collector already | |
| 2303 // has the world stopped and would deadlock. | |
| 2304 while (_collectorState != Idling) { | |
| 2305 if (TraceCMSState) { | |
| 2306 gclog_or_tty->print_cr("Thread " INTPTR_FORMAT " in CMS state %d", | |
| 2307 Thread::current(), _collectorState); | |
| 2308 } | |
| 2309 // The foreground collector | |
| 2310 // holds the Heap_lock throughout its collection. | |
| 2311 // holds the CMS token (but not the lock) | |
| 2312 // except while it is waiting for the background collector to yield. | |
| 2313 // | |
| 2314 // The foreground collector should be blocked (not for long) | |
| 2315 // if the background collector is about to start a phase | |
| 2316 // executed with world stopped. If the background | |
| 2317 // collector has already started such a phase, the | |
| 2318 // foreground collector is blocked waiting for the | |
| 2319 // Heap_lock. The stop-world phases (InitialMarking and FinalMarking) | |
| 2320 // are executed in the VM thread. | |
| 2321 // | |
| 2322 // The locking order is | |
| 2323 // PendingListLock (PLL) -- if applicable (FinalMarking) | |
| 2324 // Heap_lock (both this & PLL locked in VM_CMS_Operation::prologue()) | |
| 2325 // CMS token (claimed in | |
| 2326 // stop_world_and_do() --> | |
| 2327 // safepoint_synchronize() --> | |
| 2328 // CMSThread::synchronize()) | |
| 2329 | |
| 2330 { | |
| 2331 // Check if the FG collector wants us to yield. | |
| 2332 CMSTokenSync x(true); // is cms thread | |
| 2333 if (waitForForegroundGC()) { | |
| 2334 // We yielded to a foreground GC, nothing more to be | |
| 2335 // done this round. | |
| 2336 assert(_foregroundGCShouldWait == false, "We set it to false in " | |
| 2337 "waitForForegroundGC()"); | |
| 2338 if (TraceCMSState) { | |
| 2339 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT | |
| 2340 " exiting collection CMS state %d", | |
| 2341 Thread::current(), _collectorState); | |
| 2342 } | |
| 2343 return; | |
| 2344 } else { | |
| 2345 // The background collector can run but check to see if the | |
| 2346 // foreground collector has done a collection while the | |
| 2347 // background collector was waiting to get the CGC_lock | |
| 2348 // above. If yes, break so that _foregroundGCShouldWait | |
| 2349 // is cleared before returning. | |
| 2350 if (_collectorState == Idling) { | |
| 2351 break; | |
| 2352 } | |
| 2353 } | |
| 2354 } | |
| 2355 | |
| 2356 assert(_foregroundGCShouldWait, "Foreground collector, if active, " | |
| 2357 "should be waiting"); | |
| 2358 | |
| 2359 switch (_collectorState) { | |
| 2360 case InitialMarking: | |
| 2361 { | |
| 2362 ReleaseForegroundGC x(this); | |
| 2363 stats().record_cms_begin(); | |
| 2364 VM_CMS_Initial_Mark initial_mark_op(this); | |
| 2365 VMThread::execute(&initial_mark_op); | |
| 2366 } | |
| 2367 // The collector state may be any legal state at this point | |
| 2368 // since the background collector may have yielded to the | |
| 2369 // foreground collector. | |
| 2370 break; | |
| 2371 case Marking: | |
| 2372 // initial marking in checkpointRootsInitialWork has been completed | |
| 2373 if (markFromRoots(true)) { // we were successful | |
| 2374 assert(_collectorState == Precleaning, "Collector state should " | |
| 2375 "have changed"); | |
| 2376 } else { | |
| 2377 assert(_foregroundGCIsActive, "Internal state inconsistency"); | |
| 2378 } | |
| 2379 break; | |
| 2380 case Precleaning: | |
| 2381 if (UseAdaptiveSizePolicy) { | |
| 2382 size_policy()->concurrent_precleaning_begin(); | |
| 2383 } | |
| 2384 // marking from roots in markFromRoots has been completed | |
| 2385 preclean(); | |
| 2386 if (UseAdaptiveSizePolicy) { | |
| 2387 size_policy()->concurrent_precleaning_end(); | |
| 2388 } | |
| 2389 assert(_collectorState == AbortablePreclean || | |
| 2390 _collectorState == FinalMarking, | |
| 2391 "Collector state should have changed"); | |
| 2392 break; | |
| 2393 case AbortablePreclean: | |
| 2394 if (UseAdaptiveSizePolicy) { | |
| 2395 size_policy()->concurrent_phases_resume(); | |
| 2396 } | |
| 2397 abortable_preclean(); | |
| 2398 if (UseAdaptiveSizePolicy) { | |
| 2399 size_policy()->concurrent_precleaning_end(); | |
| 2400 } | |
| 2401 assert(_collectorState == FinalMarking, "Collector state should " | |
| 2402 "have changed"); | |
| 2403 break; | |
| 2404 case FinalMarking: | |
| 2405 { | |
| 2406 ReleaseForegroundGC x(this); | |
| 2407 | |
| 2408 VM_CMS_Final_Remark final_remark_op(this); | |
| 2409 VMThread::execute(&final_remark_op); | |
| 935 | 2410 } |
| 0 | 2411 assert(_foregroundGCShouldWait, "block post-condition"); |
| 2412 break; | |
| 2413 case Sweeping: | |
| 2414 if (UseAdaptiveSizePolicy) { | |
| 2415 size_policy()->concurrent_sweeping_begin(); | |
| 2416 } | |
| 2417 // final marking in checkpointRootsFinal has been completed | |
| 2418 sweep(true); | |
| 2419 assert(_collectorState == Resizing, "Collector state change " | |
| 2420 "to Resizing must be done under the free_list_lock"); | |
| 2421 _full_gcs_since_conc_gc = 0; | |
| 2422 | |
| 2423 // Stop the timers for adaptive size policy for the concurrent phases | |
| 2424 if (UseAdaptiveSizePolicy) { | |
| 2425 size_policy()->concurrent_sweeping_end(); | |
| 2426 size_policy()->concurrent_phases_end(gch->gc_cause(), | |
| 2427 gch->prev_gen(_cmsGen)->capacity(), | |
| 2428 _cmsGen->free()); | |
| 2429 } | |
| 2430 | |
| 2431 case Resizing: { | |
| 2432 // Sweeping has been completed... | |
| 2433 // At this point the background collection has completed. | |
| 2434 // Don't move the call to compute_new_size() down | |
| 2435 // into code that might be executed if the background | |
| 2436 // collection was preempted. | |
| 2437 { | |
| 2438 ReleaseForegroundGC x(this); // unblock FG collection | |
| 2439 MutexLockerEx y(Heap_lock, Mutex::_no_safepoint_check_flag); | |
| 2440 CMSTokenSync z(true); // not strictly needed. | |
| 2441 if (_collectorState == Resizing) { | |
| 2442 compute_new_size(); | |
| 10405 | 2443 save_heap_summary(); |
| 0 | 2444 _collectorState = Resetting; |
| 2445 } else { | |
| 2446 assert(_collectorState == Idling, "The state should only change" | |
| 2447 " because the foreground collector has finished the collection"); | |
| 2448 } | |
| 2449 } | |
| 2450 break; | |
| 2451 } | |
| 2452 case Resetting: | |
| 2453 // CMS heap resizing has been completed | |
| 2454 reset(true); | |
| 2455 assert(_collectorState == Idling, "Collector state should " | |
| 2456 "have changed"); | |
|
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2457 |
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2458 MetaspaceGC::set_should_concurrent_collect(false); |
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2459 |
| 0 | 2460 stats().record_cms_end(); |
| 2461 // Don't move the concurrent_phases_end() and compute_new_size() | |
| 2462 // calls to here because a preempted background collection | |
| 2463 // has it's state set to "Resetting". | |
| 2464 break; | |
| 2465 case Idling: | |
| 2466 default: | |
| 2467 ShouldNotReachHere(); | |
| 2468 break; | |
| 2469 } | |
| 2470 if (TraceCMSState) { | |
| 2471 gclog_or_tty->print_cr(" Thread " INTPTR_FORMAT " done - next CMS state %d", | |
| 2472 Thread::current(), _collectorState); | |
| 2473 } | |
| 2474 assert(_foregroundGCShouldWait, "block post-condition"); | |
| 2475 } | |
| 2476 | |
| 2477 // Should this be in gc_epilogue? | |
| 2478 collector_policy()->counters()->update_counters(); | |
| 2479 | |
| 2480 { | |
| 2481 // Clear _foregroundGCShouldWait and, in the event that the | |
| 2482 // foreground collector is waiting, notify it, before | |
| 2483 // returning. | |
| 2484 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
| 2485 _foregroundGCShouldWait = false; | |
| 2486 if (_foregroundGCIsActive) { | |
| 2487 CGC_lock->notify(); | |
| 2488 } | |
| 2489 assert(!ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 2490 "Possible deadlock"); | |
| 2491 } | |
| 2492 if (TraceCMSState) { | |
| 2493 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT | |
| 2494 " exiting collection CMS state %d", | |
| 2495 Thread::current(), _collectorState); | |
| 2496 } | |
| 2497 if (PrintGC && Verbose) { | |
| 2498 _cmsGen->print_heap_change(prev_used); | |
| 2499 } | |
| 2500 } | |
| 2501 | |
| 10405 | 2502 void CMSCollector::register_foreground_gc_start(GCCause::Cause cause) { |
| 2503 if (!_cms_start_registered) { | |
| 2504 register_gc_start(cause); | |
| 2505 } | |
| 2506 } | |
| 2507 | |
| 2508 void CMSCollector::register_gc_start(GCCause::Cause cause) { | |
| 2509 _cms_start_registered = true; | |
|
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|
2510 _gc_timer_cm->register_gc_start(); |
| 10405 | 2511 _gc_tracer_cm->report_gc_start(cause, _gc_timer_cm->gc_start()); |
| 2512 } | |
| 2513 | |
| 2514 void CMSCollector::register_gc_end() { | |
| 2515 if (_cms_start_registered) { | |
| 2516 report_heap_summary(GCWhen::AfterGC); | |
| 2517 | |
|
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|
2518 _gc_timer_cm->register_gc_end(); |
| 10405 | 2519 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); |
| 2520 _cms_start_registered = false; | |
| 2521 } | |
| 2522 } | |
| 2523 | |
| 2524 void CMSCollector::save_heap_summary() { | |
| 2525 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 2526 _last_heap_summary = gch->create_heap_summary(); | |
| 2527 _last_metaspace_summary = gch->create_metaspace_summary(); | |
| 2528 } | |
| 2529 | |
| 2530 void CMSCollector::report_heap_summary(GCWhen::Type when) { | |
|
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|
2531 _gc_tracer_cm->report_gc_heap_summary(when, _last_heap_summary); |
|
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|
2532 _gc_tracer_cm->report_metaspace_summary(when, _last_metaspace_summary); |
| 10405 | 2533 } |
| 2534 | |
| 2535 void CMSCollector::collect_in_foreground(bool clear_all_soft_refs, GCCause::Cause cause) { | |
| 0 | 2536 assert(_foregroundGCIsActive && !_foregroundGCShouldWait, |
| 2537 "Foreground collector should be waiting, not executing"); | |
| 2538 assert(Thread::current()->is_VM_thread(), "A foreground collection" | |
| 2539 "may only be done by the VM Thread with the world stopped"); | |
| 2540 assert(ConcurrentMarkSweepThread::vm_thread_has_cms_token(), | |
| 2541 "VM thread should have CMS token"); | |
| 2542 | |
|
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|
2543 // The gc id is created in register_foreground_gc_start if this collection is synchronous |
|
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|
2544 const GCId gc_id = _collectorState == InitialMarking ? GCId::peek() : _gc_tracer_cm->gc_id(); |
| 10405 | 2545 NOT_PRODUCT(GCTraceTime t("CMS:MS (foreground) ", PrintGCDetails && Verbose, |
|
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|
2546 true, NULL, gc_id);) |
| 0 | 2547 if (UseAdaptiveSizePolicy) { |
| 2548 size_policy()->ms_collection_begin(); | |
| 2549 } | |
| 2550 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact); | |
| 2551 | |
| 2552 HandleMark hm; // Discard invalid handles created during verification | |
| 2553 | |
| 2554 if (VerifyBeforeGC && | |
| 2555 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
|
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|
2556 Universe::verify(); |
| 0 | 2557 } |
| 2558 | |
|
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|
2559 // Snapshot the soft reference policy to be used in this collection cycle. |
|
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|
2560 ref_processor()->setup_policy(clear_all_soft_refs); |
|
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|
2561 |
|
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|
2562 // Decide if class unloading should be done |
|
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|
2563 update_should_unload_classes(); |
|
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|
2564 |
| 0 | 2565 bool init_mark_was_synchronous = false; // until proven otherwise |
| 2566 while (_collectorState != Idling) { | |
| 2567 if (TraceCMSState) { | |
| 2568 gclog_or_tty->print_cr("Thread " INTPTR_FORMAT " in CMS state %d", | |
| 2569 Thread::current(), _collectorState); | |
| 2570 } | |
| 2571 switch (_collectorState) { | |
| 2572 case InitialMarking: | |
| 10405 | 2573 register_foreground_gc_start(cause); |
| 0 | 2574 init_mark_was_synchronous = true; // fact to be exploited in re-mark |
| 2575 checkpointRootsInitial(false); | |
| 2576 assert(_collectorState == Marking, "Collector state should have changed" | |
| 2577 " within checkpointRootsInitial()"); | |
| 2578 break; | |
| 2579 case Marking: | |
| 2580 // initial marking in checkpointRootsInitialWork has been completed | |
| 2581 if (VerifyDuringGC && | |
| 2582 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
|
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|
2583 Universe::verify("Verify before initial mark: "); |
| 0 | 2584 } |
| 2585 { | |
| 2586 bool res = markFromRoots(false); | |
| 2587 assert(res && _collectorState == FinalMarking, "Collector state should " | |
| 2588 "have changed"); | |
| 2589 break; | |
| 2590 } | |
| 2591 case FinalMarking: | |
| 2592 if (VerifyDuringGC && | |
| 2593 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
|
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|
2594 Universe::verify("Verify before re-mark: "); |
| 0 | 2595 } |
| 2596 checkpointRootsFinal(false, clear_all_soft_refs, | |
| 2597 init_mark_was_synchronous); | |
| 2598 assert(_collectorState == Sweeping, "Collector state should not " | |
| 2599 "have changed within checkpointRootsFinal()"); | |
| 2600 break; | |
| 2601 case Sweeping: | |
| 2602 // final marking in checkpointRootsFinal has been completed | |
| 2603 if (VerifyDuringGC && | |
| 2604 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
|
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|
2605 Universe::verify("Verify before sweep: "); |
| 0 | 2606 } |
| 2607 sweep(false); | |
| 2608 assert(_collectorState == Resizing, "Incorrect state"); | |
| 2609 break; | |
| 2610 case Resizing: { | |
| 2611 // Sweeping has been completed; the actual resize in this case | |
| 2612 // is done separately; nothing to be done in this state. | |
| 2613 _collectorState = Resetting; | |
| 2614 break; | |
| 2615 } | |
| 2616 case Resetting: | |
| 2617 // The heap has been resized. | |
| 2618 if (VerifyDuringGC && | |
| 2619 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
|
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|
2620 Universe::verify("Verify before reset: "); |
| 0 | 2621 } |
| 10405 | 2622 save_heap_summary(); |
| 0 | 2623 reset(false); |
| 2624 assert(_collectorState == Idling, "Collector state should " | |
| 2625 "have changed"); | |
| 2626 break; | |
| 2627 case Precleaning: | |
| 2628 case AbortablePreclean: | |
| 2629 // Elide the preclean phase | |
| 2630 _collectorState = FinalMarking; | |
| 2631 break; | |
| 2632 default: | |
| 2633 ShouldNotReachHere(); | |
| 2634 } | |
| 2635 if (TraceCMSState) { | |
| 2636 gclog_or_tty->print_cr(" Thread " INTPTR_FORMAT " done - next CMS state %d", | |
| 2637 Thread::current(), _collectorState); | |
| 2638 } | |
| 2639 } | |
| 2640 | |
| 2641 if (UseAdaptiveSizePolicy) { | |
| 2642 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 2643 size_policy()->ms_collection_end(gch->gc_cause()); | |
| 2644 } | |
| 2645 | |
| 2646 if (VerifyAfterGC && | |
| 2647 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
|
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|
2648 Universe::verify(); |
| 0 | 2649 } |
| 2650 if (TraceCMSState) { | |
| 2651 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT | |
| 2652 " exiting collection CMS state %d", | |
| 2653 Thread::current(), _collectorState); | |
| 2654 } | |
| 2655 } | |
| 2656 | |
| 2657 bool CMSCollector::waitForForegroundGC() { | |
| 2658 bool res = false; | |
| 2659 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 2660 "CMS thread should have CMS token"); | |
| 2661 // Block the foreground collector until the | |
| 2662 // background collectors decides whether to | |
| 2663 // yield. | |
| 2664 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
| 2665 _foregroundGCShouldWait = true; | |
| 2666 if (_foregroundGCIsActive) { | |
| 2667 // The background collector yields to the | |
| 2668 // foreground collector and returns a value | |
| 2669 // indicating that it has yielded. The foreground | |
| 2670 // collector can proceed. | |
| 2671 res = true; | |
| 2672 _foregroundGCShouldWait = false; | |
| 2673 ConcurrentMarkSweepThread::clear_CMS_flag( | |
| 2674 ConcurrentMarkSweepThread::CMS_cms_has_token); | |
| 2675 ConcurrentMarkSweepThread::set_CMS_flag( | |
| 2676 ConcurrentMarkSweepThread::CMS_cms_wants_token); | |
| 2677 // Get a possibly blocked foreground thread going | |
| 2678 CGC_lock->notify(); | |
| 2679 if (TraceCMSState) { | |
| 2680 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT " waiting at CMS state %d", | |
| 2681 Thread::current(), _collectorState); | |
| 2682 } | |
| 2683 while (_foregroundGCIsActive) { | |
| 2684 CGC_lock->wait(Mutex::_no_safepoint_check_flag); | |
| 2685 } | |
| 2686 ConcurrentMarkSweepThread::set_CMS_flag( | |
| 2687 ConcurrentMarkSweepThread::CMS_cms_has_token); | |
| 2688 ConcurrentMarkSweepThread::clear_CMS_flag( | |
| 2689 ConcurrentMarkSweepThread::CMS_cms_wants_token); | |
| 2690 } | |
| 2691 if (TraceCMSState) { | |
| 2692 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT " continuing at CMS state %d", | |
| 2693 Thread::current(), _collectorState); | |
| 2694 } | |
| 2695 return res; | |
| 2696 } | |
| 2697 | |
| 2698 // Because of the need to lock the free lists and other structures in | |
| 2699 // the collector, common to all the generations that the collector is | |
| 2700 // collecting, we need the gc_prologues of individual CMS generations | |
| 2701 // delegate to their collector. It may have been simpler had the | |
| 2702 // current infrastructure allowed one to call a prologue on a | |
| 2703 // collector. In the absence of that we have the generation's | |
| 2704 // prologue delegate to the collector, which delegates back | |
| 2705 // some "local" work to a worker method in the individual generations | |
| 2706 // that it's responsible for collecting, while itself doing any | |
| 2707 // work common to all generations it's responsible for. A similar | |
| 2708 // comment applies to the gc_epilogue()'s. | |
| 2709 // The role of the varaible _between_prologue_and_epilogue is to | |
| 2710 // enforce the invocation protocol. | |
| 2711 void CMSCollector::gc_prologue(bool full) { | |
|
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|
2712 // Call gc_prologue_work() for the CMSGen |
| 0 | 2713 // we are responsible for. |
| 2714 | |
| 2715 // The following locking discipline assumes that we are only called | |
| 2716 // when the world is stopped. | |
| 2717 assert(SafepointSynchronize::is_at_safepoint(), "world is stopped assumption"); | |
| 2718 | |
| 2719 // The CMSCollector prologue must call the gc_prologues for the | |
|
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|
2720 // "generations" that it's responsible |
| 0 | 2721 // for. |
| 2722 | |
| 2723 assert( Thread::current()->is_VM_thread() | |
| 2724 || ( CMSScavengeBeforeRemark | |
| 2725 && Thread::current()->is_ConcurrentGC_thread()), | |
| 2726 "Incorrect thread type for prologue execution"); | |
| 2727 | |
| 2728 if (_between_prologue_and_epilogue) { | |
| 2729 // We have already been invoked; this is a gc_prologue delegation | |
| 2730 // from yet another CMS generation that we are responsible for, just | |
| 2731 // ignore it since all relevant work has already been done. | |
| 2732 return; | |
| 2733 } | |
| 2734 | |
| 2735 // set a bit saying prologue has been called; cleared in epilogue | |
| 2736 _between_prologue_and_epilogue = true; | |
| 2737 // Claim locks for common data structures, then call gc_prologue_work() | |
|
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|
2738 // for each CMSGen. |
| 0 | 2739 |
| 2740 getFreelistLocks(); // gets free list locks on constituent spaces | |
| 2741 bitMapLock()->lock_without_safepoint_check(); | |
| 2742 | |
| 2743 // Should call gc_prologue_work() for all cms gens we are responsible for | |
|
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|
2744 bool duringMarking = _collectorState >= Marking |
| 0 | 2745 && _collectorState < Sweeping; |
|
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|
2746 |
|
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|
2747 // The young collections clear the modified oops state, which tells if |
|
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diff
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|
2748 // there are any modified oops in the class. The remark phase also needs |
|
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|
2749 // that information. Tell the young collection to save the union of all |
|
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|
2750 // modified klasses. |
|
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diff
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|
2751 if (duringMarking) { |
|
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diff
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|
2752 _ct->klass_rem_set()->set_accumulate_modified_oops(true); |
|
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|
2753 } |
|
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|
2754 |
|
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|
2755 bool registerClosure = duringMarking; |
|
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|
2756 |
|
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6984287: Regularize how GC parallel workers are specified.
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diff
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|
2757 ModUnionClosure* muc = CollectedHeap::use_parallel_gc_threads() ? |
|
8b10f48633dc
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|
2758 &_modUnionClosurePar |
| 0 | 2759 : &_modUnionClosure; |
| 2760 _cmsGen->gc_prologue_work(full, registerClosure, muc); | |
| 2761 | |
| 2762 if (!full) { | |
| 2763 stats().record_gc0_begin(); | |
| 2764 } | |
| 2765 } | |
| 2766 | |
| 2767 void ConcurrentMarkSweepGeneration::gc_prologue(bool full) { | |
|
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|
2768 |
|
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diff
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|
2769 _capacity_at_prologue = capacity(); |
|
8617e38bb4cb
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diff
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|
2770 _used_at_prologue = used(); |
|
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diff
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|
2771 |
| 0 | 2772 // Delegate to CMScollector which knows how to coordinate between |
| 2773 // this and any other CMS generations that it is responsible for | |
| 2774 // collecting. | |
| 2775 collector()->gc_prologue(full); | |
| 2776 } | |
| 2777 | |
| 2778 // This is a "private" interface for use by this generation's CMSCollector. | |
| 2779 // Not to be called directly by any other entity (for instance, | |
| 2780 // GenCollectedHeap, which calls the "public" gc_prologue method above). | |
| 2781 void ConcurrentMarkSweepGeneration::gc_prologue_work(bool full, | |
| 2782 bool registerClosure, ModUnionClosure* modUnionClosure) { | |
| 2783 assert(!incremental_collection_failed(), "Shouldn't be set yet"); | |
| 2784 assert(cmsSpace()->preconsumptionDirtyCardClosure() == NULL, | |
| 2785 "Should be NULL"); | |
| 2786 if (registerClosure) { | |
| 2787 cmsSpace()->setPreconsumptionDirtyCardClosure(modUnionClosure); | |
| 2788 } | |
| 2789 cmsSpace()->gc_prologue(); | |
| 2790 // Clear stat counters | |
| 2791 NOT_PRODUCT( | |
| 2792 assert(_numObjectsPromoted == 0, "check"); | |
| 2793 assert(_numWordsPromoted == 0, "check"); | |
| 2794 if (Verbose && PrintGC) { | |
| 2795 gclog_or_tty->print("Allocated "SIZE_FORMAT" objects, " | |
| 2796 SIZE_FORMAT" bytes concurrently", | |
| 2797 _numObjectsAllocated, _numWordsAllocated*sizeof(HeapWord)); | |
| 2798 } | |
| 2799 _numObjectsAllocated = 0; | |
| 2800 _numWordsAllocated = 0; | |
| 2801 ) | |
| 2802 } | |
| 2803 | |
| 2804 void CMSCollector::gc_epilogue(bool full) { | |
| 2805 // The following locking discipline assumes that we are only called | |
| 2806 // when the world is stopped. | |
| 2807 assert(SafepointSynchronize::is_at_safepoint(), | |
| 2808 "world is stopped assumption"); | |
| 2809 | |
| 2810 // Currently the CMS epilogue (see CompactibleFreeListSpace) merely checks | |
| 2811 // if linear allocation blocks need to be appropriately marked to allow the | |
| 2812 // the blocks to be parsable. We also check here whether we need to nudge the | |
| 2813 // CMS collector thread to start a new cycle (if it's not already active). | |
| 2814 assert( Thread::current()->is_VM_thread() | |
| 2815 || ( CMSScavengeBeforeRemark | |
| 2816 && Thread::current()->is_ConcurrentGC_thread()), | |
| 2817 "Incorrect thread type for epilogue execution"); | |
| 2818 | |
| 2819 if (!_between_prologue_and_epilogue) { | |
| 2820 // We have already been invoked; this is a gc_epilogue delegation | |
| 2821 // from yet another CMS generation that we are responsible for, just | |
| 2822 // ignore it since all relevant work has already been done. | |
| 2823 return; | |
| 2824 } | |
| 2825 assert(haveFreelistLocks(), "must have freelist locks"); | |
| 2826 assert_lock_strong(bitMapLock()); | |
| 2827 | |
|
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|
2828 _ct->klass_rem_set()->set_accumulate_modified_oops(false); |
|
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|
2829 |
| 0 | 2830 _cmsGen->gc_epilogue_work(full); |
| 2831 | |
| 2832 if (_collectorState == AbortablePreclean || _collectorState == Precleaning) { | |
| 2833 // in case sampling was not already enabled, enable it | |
| 2834 _start_sampling = true; | |
| 2835 } | |
| 2836 // reset _eden_chunk_array so sampling starts afresh | |
| 2837 _eden_chunk_index = 0; | |
| 2838 | |
| 2839 size_t cms_used = _cmsGen->cmsSpace()->used(); | |
| 2840 | |
| 2841 // update performance counters - this uses a special version of | |
| 2842 // update_counters() that allows the utilization to be passed as a | |
| 2843 // parameter, avoiding multiple calls to used(). | |
| 2844 // | |
| 2845 _cmsGen->update_counters(cms_used); | |
| 2846 | |
| 2847 if (CMSIncrementalMode) { | |
| 2848 icms_update_allocation_limits(); | |
| 2849 } | |
| 2850 | |
| 2851 bitMapLock()->unlock(); | |
| 2852 releaseFreelistLocks(); | |
| 2853 | |
|
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2854 if (!CleanChunkPoolAsync) { |
|
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2855 Chunk::clean_chunk_pool(); |
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|
2856 } |
|
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2857 |
|
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|
2858 set_did_compact(false); |
| 0 | 2859 _between_prologue_and_epilogue = false; // ready for next cycle |
| 2860 } | |
| 2861 | |
| 2862 void ConcurrentMarkSweepGeneration::gc_epilogue(bool full) { | |
| 2863 collector()->gc_epilogue(full); | |
| 2864 | |
| 2865 // Also reset promotion tracking in par gc thread states. | |
|
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|
2866 if (CollectedHeap::use_parallel_gc_threads()) { |
| 0 | 2867 for (uint i = 0; i < ParallelGCThreads; i++) { |
|
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2868 _par_gc_thread_states[i]->promo.stopTrackingPromotions(i); |
| 0 | 2869 } |
| 2870 } | |
| 2871 } | |
| 2872 | |
| 2873 void ConcurrentMarkSweepGeneration::gc_epilogue_work(bool full) { | |
| 2874 assert(!incremental_collection_failed(), "Should have been cleared"); | |
| 2875 cmsSpace()->setPreconsumptionDirtyCardClosure(NULL); | |
| 2876 cmsSpace()->gc_epilogue(); | |
| 2877 // Print stat counters | |
| 2878 NOT_PRODUCT( | |
| 2879 assert(_numObjectsAllocated == 0, "check"); | |
| 2880 assert(_numWordsAllocated == 0, "check"); | |
| 2881 if (Verbose && PrintGC) { | |
| 2882 gclog_or_tty->print("Promoted "SIZE_FORMAT" objects, " | |
| 2883 SIZE_FORMAT" bytes", | |
| 2884 _numObjectsPromoted, _numWordsPromoted*sizeof(HeapWord)); | |
| 2885 } | |
| 2886 _numObjectsPromoted = 0; | |
| 2887 _numWordsPromoted = 0; | |
| 2888 ) | |
| 2889 | |
| 2890 if (PrintGC && Verbose) { | |
| 2891 // Call down the chain in contiguous_available needs the freelistLock | |
| 2892 // so print this out before releasing the freeListLock. | |
| 2893 gclog_or_tty->print(" Contiguous available "SIZE_FORMAT" bytes ", | |
| 2894 contiguous_available()); | |
| 2895 } | |
| 2896 } | |
| 2897 | |
| 2898 #ifndef PRODUCT | |
| 2899 bool CMSCollector::have_cms_token() { | |
| 2900 Thread* thr = Thread::current(); | |
| 2901 if (thr->is_VM_thread()) { | |
| 2902 return ConcurrentMarkSweepThread::vm_thread_has_cms_token(); | |
| 2903 } else if (thr->is_ConcurrentGC_thread()) { | |
| 2904 return ConcurrentMarkSweepThread::cms_thread_has_cms_token(); | |
| 2905 } else if (thr->is_GC_task_thread()) { | |
| 2906 return ConcurrentMarkSweepThread::vm_thread_has_cms_token() && | |
| 2907 ParGCRareEvent_lock->owned_by_self(); | |
| 2908 } | |
| 2909 return false; | |
| 2910 } | |
| 2911 #endif | |
| 2912 | |
| 2913 // Check reachability of the given heap address in CMS generation, | |
| 2914 // treating all other generations as roots. | |
| 2915 bool CMSCollector::is_cms_reachable(HeapWord* addr) { | |
| 2916 // We could "guarantee" below, rather than assert, but i'll | |
| 2917 // leave these as "asserts" so that an adventurous debugger | |
| 2918 // could try this in the product build provided some subset of | |
| 2919 // the conditions were met, provided they were intersted in the | |
| 2920 // results and knew that the computation below wouldn't interfere | |
| 2921 // with other concurrent computations mutating the structures | |
| 2922 // being read or written. | |
| 2923 assert(SafepointSynchronize::is_at_safepoint(), | |
| 2924 "Else mutations in object graph will make answer suspect"); | |
| 2925 assert(have_cms_token(), "Should hold cms token"); | |
| 2926 assert(haveFreelistLocks(), "must hold free list locks"); | |
| 2927 assert_lock_strong(bitMapLock()); | |
| 2928 | |
| 2929 // Clear the marking bit map array before starting, but, just | |
| 2930 // for kicks, first report if the given address is already marked | |
| 2931 gclog_or_tty->print_cr("Start: Address 0x%x is%s marked", addr, | |
| 2932 _markBitMap.isMarked(addr) ? "" : " not"); | |
| 2933 | |
| 2934 if (verify_after_remark()) { | |
| 2935 MutexLockerEx x(verification_mark_bm()->lock(), Mutex::_no_safepoint_check_flag); | |
| 2936 bool result = verification_mark_bm()->isMarked(addr); | |
| 2937 gclog_or_tty->print_cr("TransitiveMark: Address 0x%x %s marked", addr, | |
| 2938 result ? "IS" : "is NOT"); | |
| 2939 return result; | |
| 2940 } else { | |
| 2941 gclog_or_tty->print_cr("Could not compute result"); | |
| 2942 return false; | |
| 2943 } | |
| 2944 } | |
| 2945 | |
|
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2946 |
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2947 void |
|
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|
2948 CMSCollector::print_on_error(outputStream* st) { |
|
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2949 CMSCollector* collector = ConcurrentMarkSweepGeneration::_collector; |
|
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2950 if (collector != NULL) { |
|
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2951 CMSBitMap* bitmap = &collector->_markBitMap; |
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2952 st->print_cr("Marking Bits: (CMSBitMap*) " PTR_FORMAT, bitmap); |
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|
2953 bitmap->print_on_error(st, " Bits: "); |
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2954 |
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|
2955 st->cr(); |
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|
2956 |
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|
2957 CMSBitMap* mut_bitmap = &collector->_modUnionTable; |
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2958 st->print_cr("Mod Union Table: (CMSBitMap*) " PTR_FORMAT, mut_bitmap); |
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2959 mut_bitmap->print_on_error(st, " Bits: "); |
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2960 } |
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2961 } |
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|
2962 |
| 0 | 2963 //////////////////////////////////////////////////////// |
| 2964 // CMS Verification Support | |
| 2965 //////////////////////////////////////////////////////// | |
| 2966 // Following the remark phase, the following invariant | |
| 2967 // should hold -- each object in the CMS heap which is | |
| 2968 // marked in markBitMap() should be marked in the verification_mark_bm(). | |
| 2969 | |
| 2970 class VerifyMarkedClosure: public BitMapClosure { | |
| 2971 CMSBitMap* _marks; | |
| 2972 bool _failed; | |
| 2973 | |
| 2974 public: | |
| 2975 VerifyMarkedClosure(CMSBitMap* bm): _marks(bm), _failed(false) {} | |
| 2976 | |
|
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2977 bool do_bit(size_t offset) { |
| 0 | 2978 HeapWord* addr = _marks->offsetToHeapWord(offset); |
| 2979 if (!_marks->isMarked(addr)) { | |
|
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2980 oop(addr)->print_on(gclog_or_tty); |
| 0 | 2981 gclog_or_tty->print_cr(" ("INTPTR_FORMAT" should have been marked)", addr); |
| 2982 _failed = true; | |
| 2983 } | |
|
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2984 return true; |
| 0 | 2985 } |
| 2986 | |
| 2987 bool failed() { return _failed; } | |
| 2988 }; | |
| 2989 | |
|
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2990 bool CMSCollector::verify_after_remark(bool silent) { |
|
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2991 if (!silent) gclog_or_tty->print(" [Verifying CMS Marking... "); |
| 0 | 2992 MutexLockerEx ml(verification_mark_bm()->lock(), Mutex::_no_safepoint_check_flag); |
| 2993 static bool init = false; | |
| 2994 | |
| 2995 assert(SafepointSynchronize::is_at_safepoint(), | |
| 2996 "Else mutations in object graph will make answer suspect"); | |
| 2997 assert(have_cms_token(), | |
| 2998 "Else there may be mutual interference in use of " | |
| 2999 " verification data structures"); | |
| 3000 assert(_collectorState > Marking && _collectorState <= Sweeping, | |
| 3001 "Else marking info checked here may be obsolete"); | |
| 3002 assert(haveFreelistLocks(), "must hold free list locks"); | |
| 3003 assert_lock_strong(bitMapLock()); | |
| 3004 | |
| 3005 | |
| 3006 // Allocate marking bit map if not already allocated | |
| 3007 if (!init) { // first time | |
| 3008 if (!verification_mark_bm()->allocate(_span)) { | |
| 3009 return false; | |
| 3010 } | |
| 3011 init = true; | |
| 3012 } | |
| 3013 | |
| 3014 assert(verification_mark_stack()->isEmpty(), "Should be empty"); | |
| 3015 | |
| 3016 // Turn off refs discovery -- so we will be tracing through refs. | |
| 3017 // This is as intended, because by this time | |
| 3018 // GC must already have cleared any refs that need to be cleared, | |
| 3019 // and traced those that need to be marked; moreover, | |
| 3020 // the marking done here is not going to intefere in any | |
| 3021 // way with the marking information used by GC. | |
| 3022 NoRefDiscovery no_discovery(ref_processor()); | |
| 3023 | |
| 3024 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact;) | |
| 3025 | |
| 3026 // Clear any marks from a previous round | |
| 3027 verification_mark_bm()->clear_all(); | |
| 3028 assert(verification_mark_stack()->isEmpty(), "markStack should be empty"); | |
|
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|
3029 verify_work_stacks_empty(); |
| 0 | 3030 |
| 3031 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 3032 gch->ensure_parsability(false); // fill TLABs, but no need to retire them | |
| 3033 // Update the saved marks which may affect the root scans. | |
| 3034 gch->save_marks(); | |
| 3035 | |
| 3036 if (CMSRemarkVerifyVariant == 1) { | |
| 3037 // In this first variant of verification, we complete | |
| 3038 // all marking, then check if the new marks-verctor is | |
| 3039 // a subset of the CMS marks-vector. | |
| 3040 verify_after_remark_work_1(); | |
| 3041 } else if (CMSRemarkVerifyVariant == 2) { | |
| 3042 // In this second variant of verification, we flag an error | |
| 3043 // (i.e. an object reachable in the new marks-vector not reachable | |
| 3044 // in the CMS marks-vector) immediately, also indicating the | |
| 3045 // identify of an object (A) that references the unmarked object (B) -- | |
| 3046 // presumably, a mutation to A failed to be picked up by preclean/remark? | |
| 3047 verify_after_remark_work_2(); | |
| 3048 } else { | |
| 3049 warning("Unrecognized value %d for CMSRemarkVerifyVariant", | |
| 3050 CMSRemarkVerifyVariant); | |
| 3051 } | |
|
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3052 if (!silent) gclog_or_tty->print(" done] "); |
| 0 | 3053 return true; |
| 3054 } | |
| 3055 | |
| 3056 void CMSCollector::verify_after_remark_work_1() { | |
| 3057 ResourceMark rm; | |
| 3058 HandleMark hm; | |
| 3059 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 3060 | |
|
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3061 // Get a clear set of claim bits for the roots processing to work with. |
|
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3062 ClassLoaderDataGraph::clear_claimed_marks(); |
|
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3063 |
| 0 | 3064 // Mark from roots one level into CMS |
|
994
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|
3065 MarkRefsIntoClosure notOlder(_span, verification_mark_bm()); |
| 0 | 3066 gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel. |
| 3067 | |
|
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3068 gch->gen_process_roots(_cmsGen->level(), |
|
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|
3069 true, // younger gens are roots |
|
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|
3070 true, // activate StrongRootsScope |
|
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3071 GenCollectedHeap::ScanningOption(roots_scanning_options()), |
|
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3072 should_unload_classes(), |
|
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3073 ¬Older, |
|
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|
3074 NULL, |
|
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|
3075 NULL); // SSS: Provide correct closure |
| 0 | 3076 |
| 3077 // Now mark from the roots | |
| 3078 MarkFromRootsClosure markFromRootsClosure(this, _span, | |
|
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|
3079 verification_mark_bm(), verification_mark_stack(), |
| 0 | 3080 false /* don't yield */, true /* verifying */); |
| 3081 assert(_restart_addr == NULL, "Expected pre-condition"); | |
| 3082 verification_mark_bm()->iterate(&markFromRootsClosure); | |
| 3083 while (_restart_addr != NULL) { | |
| 3084 // Deal with stack overflow: by restarting at the indicated | |
| 3085 // address. | |
| 3086 HeapWord* ra = _restart_addr; | |
| 3087 markFromRootsClosure.reset(ra); | |
| 3088 _restart_addr = NULL; | |
| 3089 verification_mark_bm()->iterate(&markFromRootsClosure, ra, _span.end()); | |
| 3090 } | |
| 3091 assert(verification_mark_stack()->isEmpty(), "Should have been drained"); | |
| 3092 verify_work_stacks_empty(); | |
| 3093 | |
| 3094 // Marking completed -- now verify that each bit marked in | |
| 3095 // verification_mark_bm() is also marked in markBitMap(); flag all | |
| 3096 // errors by printing corresponding objects. | |
| 3097 VerifyMarkedClosure vcl(markBitMap()); | |
| 3098 verification_mark_bm()->iterate(&vcl); | |
| 3099 if (vcl.failed()) { | |
| 3100 gclog_or_tty->print("Verification failed"); | |
|
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3101 Universe::heap()->print_on(gclog_or_tty); |
|
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3102 fatal("CMS: failed marking verification after remark"); |
| 0 | 3103 } |
| 3104 } | |
| 3105 | |
|
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3106 class VerifyKlassOopsKlassClosure : public KlassClosure { |
|
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3107 class VerifyKlassOopsClosure : public OopClosure { |
|
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3108 CMSBitMap* _bitmap; |
|
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3109 public: |
|
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3110 VerifyKlassOopsClosure(CMSBitMap* bitmap) : _bitmap(bitmap) { } |
|
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3111 void do_oop(oop* p) { guarantee(*p == NULL || _bitmap->isMarked((HeapWord*) *p), "Should be marked"); } |
|
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3112 void do_oop(narrowOop* p) { ShouldNotReachHere(); } |
|
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|
3113 } _oop_closure; |
|
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3114 public: |
|
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|
3115 VerifyKlassOopsKlassClosure(CMSBitMap* bitmap) : _oop_closure(bitmap) {} |
|
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|
3116 void do_klass(Klass* k) { |
|
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3117 k->oops_do(&_oop_closure); |
|
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3118 } |
|
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|
3119 }; |
|
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|
3120 |
| 0 | 3121 void CMSCollector::verify_after_remark_work_2() { |
| 3122 ResourceMark rm; | |
| 3123 HandleMark hm; | |
| 3124 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 3125 | |
|
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3126 // Get a clear set of claim bits for the roots processing to work with. |
|
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3127 ClassLoaderDataGraph::clear_claimed_marks(); |
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3128 |
| 0 | 3129 // Mark from roots one level into CMS |
| 3130 MarkRefsIntoVerifyClosure notOlder(_span, verification_mark_bm(), | |
|
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3131 markBitMap()); |
|
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3132 CLDToOopClosure cld_closure(¬Older, true); |
|
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3133 |
| 0 | 3134 gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel. |
|
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3135 |
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3136 gch->gen_process_roots(_cmsGen->level(), |
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3137 true, // younger gens are roots |
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3138 true, // activate StrongRootsScope |
|
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3139 GenCollectedHeap::ScanningOption(roots_scanning_options()), |
|
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3140 should_unload_classes(), |
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3141 ¬Older, |
|
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|
3142 NULL, |
|
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|
3143 &cld_closure); |
| 0 | 3144 |
| 3145 // Now mark from the roots | |
| 3146 MarkFromRootsVerifyClosure markFromRootsClosure(this, _span, | |
| 3147 verification_mark_bm(), markBitMap(), verification_mark_stack()); | |
| 3148 assert(_restart_addr == NULL, "Expected pre-condition"); | |
| 3149 verification_mark_bm()->iterate(&markFromRootsClosure); | |
| 3150 while (_restart_addr != NULL) { | |
| 3151 // Deal with stack overflow: by restarting at the indicated | |
| 3152 // address. | |
| 3153 HeapWord* ra = _restart_addr; | |
| 3154 markFromRootsClosure.reset(ra); | |
| 3155 _restart_addr = NULL; | |
| 3156 verification_mark_bm()->iterate(&markFromRootsClosure, ra, _span.end()); | |
| 3157 } | |
| 3158 assert(verification_mark_stack()->isEmpty(), "Should have been drained"); | |
| 3159 verify_work_stacks_empty(); | |
|
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3160 |
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3161 VerifyKlassOopsKlassClosure verify_klass_oops(verification_mark_bm()); |
|
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3162 ClassLoaderDataGraph::classes_do(&verify_klass_oops); |
| 0 | 3163 |
| 3164 // Marking completed -- now verify that each bit marked in | |
| 3165 // verification_mark_bm() is also marked in markBitMap(); flag all | |
| 3166 // errors by printing corresponding objects. | |
| 3167 VerifyMarkedClosure vcl(markBitMap()); | |
| 3168 verification_mark_bm()->iterate(&vcl); | |
| 3169 assert(!vcl.failed(), "Else verification above should not have succeeded"); | |
| 3170 } | |
| 3171 | |
| 3172 void ConcurrentMarkSweepGeneration::save_marks() { | |
| 3173 // delegate to CMS space | |
| 3174 cmsSpace()->save_marks(); | |
| 3175 for (uint i = 0; i < ParallelGCThreads; i++) { | |
| 3176 _par_gc_thread_states[i]->promo.startTrackingPromotions(); | |
| 3177 } | |
| 3178 } | |
| 3179 | |
| 3180 bool ConcurrentMarkSweepGeneration::no_allocs_since_save_marks() { | |
| 3181 return cmsSpace()->no_allocs_since_save_marks(); | |
| 3182 } | |
| 3183 | |
| 3184 #define CMS_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \ | |
| 3185 \ | |
| 3186 void ConcurrentMarkSweepGeneration:: \ | |
| 3187 oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) { \ | |
| 3188 cl->set_generation(this); \ | |
| 3189 cmsSpace()->oop_since_save_marks_iterate##nv_suffix(cl); \ | |
| 3190 cl->reset_generation(); \ | |
| 3191 save_marks(); \ | |
| 3192 } | |
| 3193 | |
| 3194 ALL_SINCE_SAVE_MARKS_CLOSURES(CMS_SINCE_SAVE_MARKS_DEFN) | |
| 3195 | |
| 3196 void | |
| 3197 ConcurrentMarkSweepGeneration::younger_refs_iterate(OopsInGenClosure* cl) { | |
| 3198 cl->set_generation(this); | |
| 3199 younger_refs_in_space_iterate(_cmsSpace, cl); | |
| 3200 cl->reset_generation(); | |
| 3201 } | |
| 3202 | |
| 3203 void | |
|
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3204 ConcurrentMarkSweepGeneration::oop_iterate(ExtendedOopClosure* cl) { |
| 0 | 3205 if (freelistLock()->owned_by_self()) { |
| 3206 Generation::oop_iterate(cl); | |
| 3207 } else { | |
| 3208 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 3209 Generation::oop_iterate(cl); | |
| 3210 } | |
| 3211 } | |
| 3212 | |
| 3213 void | |
| 3214 ConcurrentMarkSweepGeneration::object_iterate(ObjectClosure* cl) { | |
| 3215 if (freelistLock()->owned_by_self()) { | |
| 3216 Generation::object_iterate(cl); | |
| 3217 } else { | |
| 3218 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 3219 Generation::object_iterate(cl); | |
| 3220 } | |
| 3221 } | |
| 3222 | |
| 3223 void | |
|
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3224 ConcurrentMarkSweepGeneration::safe_object_iterate(ObjectClosure* cl) { |
|
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|
3225 if (freelistLock()->owned_by_self()) { |
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|
3226 Generation::safe_object_iterate(cl); |
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|
3227 } else { |
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|
3228 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); |
|
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|
3229 Generation::safe_object_iterate(cl); |
|
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|
3230 } |
|
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|
3231 } |
|
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3232 |
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|
3233 void |
| 0 | 3234 ConcurrentMarkSweepGeneration::post_compact() { |
| 3235 } | |
| 3236 | |
| 3237 void | |
| 3238 ConcurrentMarkSweepGeneration::prepare_for_verify() { | |
| 3239 // Fix the linear allocation blocks to look like free blocks. | |
| 3240 | |
| 3241 // Locks are normally acquired/released in gc_prologue/gc_epilogue, but those | |
| 3242 // are not called when the heap is verified during universe initialization and | |
| 3243 // at vm shutdown. | |
| 3244 if (freelistLock()->owned_by_self()) { | |
| 3245 cmsSpace()->prepare_for_verify(); | |
| 3246 } else { | |
| 3247 MutexLockerEx fll(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 3248 cmsSpace()->prepare_for_verify(); | |
| 3249 } | |
| 3250 } | |
| 3251 | |
| 3252 void | |
| 6008 | 3253 ConcurrentMarkSweepGeneration::verify() { |
| 0 | 3254 // Locks are normally acquired/released in gc_prologue/gc_epilogue, but those |
| 3255 // are not called when the heap is verified during universe initialization and | |
| 3256 // at vm shutdown. | |
| 3257 if (freelistLock()->owned_by_self()) { | |
| 6008 | 3258 cmsSpace()->verify(); |
| 0 | 3259 } else { |
| 3260 MutexLockerEx fll(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 6008 | 3261 cmsSpace()->verify(); |
| 3262 } | |
| 3263 } | |
| 3264 | |
| 3265 void CMSCollector::verify() { | |
| 3266 _cmsGen->verify(); | |
| 0 | 3267 } |
| 3268 | |
| 3269 #ifndef PRODUCT | |
| 3270 bool CMSCollector::overflow_list_is_empty() const { | |
| 3271 assert(_num_par_pushes >= 0, "Inconsistency"); | |
| 3272 if (_overflow_list == NULL) { | |
| 3273 assert(_num_par_pushes == 0, "Inconsistency"); | |
| 3274 } | |
| 3275 return _overflow_list == NULL; | |
| 3276 } | |
| 3277 | |
| 3278 // The methods verify_work_stacks_empty() and verify_overflow_empty() | |
| 3279 // merely consolidate assertion checks that appear to occur together frequently. | |
| 3280 void CMSCollector::verify_work_stacks_empty() const { | |
| 3281 assert(_markStack.isEmpty(), "Marking stack should be empty"); | |
| 3282 assert(overflow_list_is_empty(), "Overflow list should be empty"); | |
| 3283 } | |
| 3284 | |
| 3285 void CMSCollector::verify_overflow_empty() const { | |
| 3286 assert(overflow_list_is_empty(), "Overflow list should be empty"); | |
| 3287 assert(no_preserved_marks(), "No preserved marks"); | |
| 3288 } | |
| 3289 #endif // PRODUCT | |
| 3290 | |
|
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|
3291 // Decide if we want to enable class unloading as part of the |
|
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|
3292 // ensuing concurrent GC cycle. We will collect and |
|
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|
3293 // unload classes if it's the case that: |
|
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|
3294 // (1) an explicit gc request has been made and the flag |
|
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|
3295 // ExplicitGCInvokesConcurrentAndUnloadsClasses is set, OR |
|
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|
3296 // (2) (a) class unloading is enabled at the command line, and |
|
6725
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|
3297 // (b) old gen is getting really full |
|
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|
3298 // NOTE: Provided there is no change in the state of the heap between |
|
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|
3299 // calls to this method, it should have idempotent results. Moreover, |
|
0834225a7916
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|
3300 // its results should be monotonically increasing (i.e. going from 0 to 1, |
|
0834225a7916
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|
3301 // but not 1 to 0) between successive calls between which the heap was |
|
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|
3302 // not collected. For the implementation below, it must thus rely on |
|
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|
3303 // the property that concurrent_cycles_since_last_unload() |
|
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|
3304 // will not decrease unless a collection cycle happened and that |
|
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|
3305 // _cmsGen->is_too_full() are |
|
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|
3306 // themselves also monotonic in that sense. See check_monotonicity() |
|
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|
3307 // below. |
|
6725
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|
3308 void CMSCollector::update_should_unload_classes() { |
|
94
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|
3309 _should_unload_classes = false; |
|
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|
3310 // Condition 1 above |
|
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|
3311 if (_full_gc_requested && ExplicitGCInvokesConcurrentAndUnloadsClasses) { |
|
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|
3312 _should_unload_classes = true; |
|
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|
3313 } else if (CMSClassUnloadingEnabled) { // Condition 2.a above |
|
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|
3314 // Disjuncts 2.b.(i,ii,iii) above |
|
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|
3315 _should_unload_classes = (concurrent_cycles_since_last_unload() >= |
|
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|
3316 CMSClassUnloadingMaxInterval) |
|
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|
3317 || _cmsGen->is_too_full(); |
|
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|
3318 } |
|
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|
3319 } |
|
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|
3320 |
|
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|
3321 bool ConcurrentMarkSweepGeneration::is_too_full() const { |
|
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|
3322 bool res = should_concurrent_collect(); |
|
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|
3323 res = res && (occupancy() > (double)CMSIsTooFullPercentage/100.0); |
|
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|
3324 return res; |
|
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|
3325 } |
|
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|
3326 |
| 0 | 3327 void CMSCollector::setup_cms_unloading_and_verification_state() { |
|
3293
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|
3328 const bool should_verify = VerifyBeforeGC || VerifyAfterGC || VerifyDuringGC |
| 0 | 3329 || VerifyBeforeExit; |
|
23224
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|
3330 const int rso = GenCollectedHeap::SO_AllCodeCache; |
| 0 | 3331 |
|
13063
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|
3332 // We set the proper root for this CMS cycle here. |
|
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|
3333 if (should_unload_classes()) { // Should unload classes this cycle |
| 0 | 3334 remove_root_scanning_option(rso); // Shrink the root set appropriately |
| 3335 set_verifying(should_verify); // Set verification state for this cycle | |
| 3336 return; // Nothing else needs to be done at this time | |
| 3337 } | |
| 3338 | |
| 3339 // Not unloading classes this cycle | |
|
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|
3340 assert(!should_unload_classes(), "Inconsitency!"); |
|
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|
3341 |
| 23164 | 3342 // If we are not unloading classes then add SO_AllCodeCache to root |
| 3343 // scanning options. | |
| 3344 add_root_scanning_option(rso); | |
| 3345 | |
|
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|
3346 if ((!verifying() || unloaded_classes_last_cycle()) && should_verify) { |
| 0 | 3347 set_verifying(true); |
| 3348 } else if (verifying() && !should_verify) { | |
| 3349 // We were verifying, but some verification flags got disabled. | |
| 3350 set_verifying(false); | |
| 3351 // Exclude symbols, strings and code cache elements from root scanning to | |
| 3352 // reduce IM and RM pauses. | |
| 3353 remove_root_scanning_option(rso); | |
| 3354 } | |
| 3355 } | |
| 3356 | |
| 3357 | |
| 3358 #ifndef PRODUCT | |
| 3359 HeapWord* CMSCollector::block_start(const void* p) const { | |
| 3360 const HeapWord* addr = (HeapWord*)p; | |
| 3361 if (_span.contains(p)) { | |
| 3362 if (_cmsGen->cmsSpace()->is_in_reserved(addr)) { | |
| 3363 return _cmsGen->cmsSpace()->block_start(p); | |
| 3364 } | |
| 3365 } | |
| 3366 return NULL; | |
| 3367 } | |
| 3368 #endif | |
| 3369 | |
| 3370 HeapWord* | |
| 3371 ConcurrentMarkSweepGeneration::expand_and_allocate(size_t word_size, | |
| 3372 bool tlab, | |
| 3373 bool parallel) { | |
|
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|
3374 CMSSynchronousYieldRequest yr; |
| 0 | 3375 assert(!tlab, "Can't deal with TLAB allocation"); |
| 3376 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 3377 expand(word_size*HeapWordSize, MinHeapDeltaBytes, | |
| 3378 CMSExpansionCause::_satisfy_allocation); | |
| 3379 if (GCExpandToAllocateDelayMillis > 0) { | |
| 3380 os::sleep(Thread::current(), GCExpandToAllocateDelayMillis, false); | |
| 3381 } | |
|
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|
3382 return have_lock_and_allocate(word_size, tlab); |
| 0 | 3383 } |
| 3384 | |
| 3385 // YSR: All of this generation expansion/shrinking stuff is an exact copy of | |
| 3386 // OneContigSpaceCardGeneration, which makes me wonder if we should move this | |
| 3387 // to CardGeneration and share it... | |
|
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|
3388 bool ConcurrentMarkSweepGeneration::expand(size_t bytes, size_t expand_bytes) { |
|
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|
3389 return CardGeneration::expand(bytes, expand_bytes); |
|
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|
3390 } |
|
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|
3391 |
| 0 | 3392 void ConcurrentMarkSweepGeneration::expand(size_t bytes, size_t expand_bytes, |
| 3393 CMSExpansionCause::Cause cause) | |
| 3394 { | |
|
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|
3395 |
|
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|
3396 bool success = expand(bytes, expand_bytes); |
|
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|
3397 |
| 0 | 3398 // remember why we expanded; this information is used |
| 3399 // by shouldConcurrentCollect() when making decisions on whether to start | |
| 3400 // a new CMS cycle. | |
| 3401 if (success) { | |
| 3402 set_expansion_cause(cause); | |
| 3403 if (PrintGCDetails && Verbose) { | |
| 3404 gclog_or_tty->print_cr("Expanded CMS gen for %s", | |
| 3405 CMSExpansionCause::to_string(cause)); | |
| 3406 } | |
| 3407 } | |
| 3408 } | |
| 3409 | |
| 3410 HeapWord* ConcurrentMarkSweepGeneration::expand_and_par_lab_allocate(CMSParGCThreadState* ps, size_t word_sz) { | |
| 3411 HeapWord* res = NULL; | |
| 3412 MutexLocker x(ParGCRareEvent_lock); | |
| 3413 while (true) { | |
| 3414 // Expansion by some other thread might make alloc OK now: | |
| 3415 res = ps->lab.alloc(word_sz); | |
| 3416 if (res != NULL) return res; | |
| 3417 // If there's not enough expansion space available, give up. | |
| 3418 if (_virtual_space.uncommitted_size() < (word_sz * HeapWordSize)) { | |
| 3419 return NULL; | |
| 3420 } | |
| 3421 // Otherwise, we try expansion. | |
| 3422 expand(word_sz*HeapWordSize, MinHeapDeltaBytes, | |
| 3423 CMSExpansionCause::_allocate_par_lab); | |
| 3424 // Now go around the loop and try alloc again; | |
| 3425 // A competing par_promote might beat us to the expansion space, | |
| 3426 // so we may go around the loop again if promotion fails agaion. | |
| 3427 if (GCExpandToAllocateDelayMillis > 0) { | |
| 3428 os::sleep(Thread::current(), GCExpandToAllocateDelayMillis, false); | |
| 3429 } | |
| 3430 } | |
| 3431 } | |
| 3432 | |
| 3433 | |
| 3434 bool ConcurrentMarkSweepGeneration::expand_and_ensure_spooling_space( | |
| 3435 PromotionInfo* promo) { | |
| 3436 MutexLocker x(ParGCRareEvent_lock); | |
| 3437 size_t refill_size_bytes = promo->refillSize() * HeapWordSize; | |
| 3438 while (true) { | |
| 3439 // Expansion by some other thread might make alloc OK now: | |
| 3440 if (promo->ensure_spooling_space()) { | |
| 3441 assert(promo->has_spooling_space(), | |
| 3442 "Post-condition of successful ensure_spooling_space()"); | |
| 3443 return true; | |
| 3444 } | |
| 3445 // If there's not enough expansion space available, give up. | |
| 3446 if (_virtual_space.uncommitted_size() < refill_size_bytes) { | |
| 3447 return false; | |
| 3448 } | |
| 3449 // Otherwise, we try expansion. | |
| 3450 expand(refill_size_bytes, MinHeapDeltaBytes, | |
| 3451 CMSExpansionCause::_allocate_par_spooling_space); | |
| 3452 // Now go around the loop and try alloc again; | |
| 3453 // A competing allocation might beat us to the expansion space, | |
| 3454 // so we may go around the loop again if allocation fails again. | |
| 3455 if (GCExpandToAllocateDelayMillis > 0) { | |
| 3456 os::sleep(Thread::current(), GCExpandToAllocateDelayMillis, false); | |
| 3457 } | |
| 3458 } | |
| 3459 } | |
| 3460 | |
| 3461 | |
|
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3462 void ConcurrentMarkSweepGeneration::shrink_by(size_t bytes) { |
|
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|
3463 assert_locked_or_safepoint(ExpandHeap_lock); |
|
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|
3464 // Shrink committed space |
|
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|
3465 _virtual_space.shrink_by(bytes); |
|
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3466 // Shrink space; this also shrinks the space's BOT |
|
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|
3467 _cmsSpace->set_end((HeapWord*) _virtual_space.high()); |
|
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|
3468 size_t new_word_size = heap_word_size(_cmsSpace->capacity()); |
|
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|
3469 // Shrink the shared block offset array |
|
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|
3470 _bts->resize(new_word_size); |
|
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|
3471 MemRegion mr(_cmsSpace->bottom(), new_word_size); |
|
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|
3472 // Shrink the card table |
|
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|
3473 Universe::heap()->barrier_set()->resize_covered_region(mr); |
|
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|
3474 |
|
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|
3475 if (Verbose && PrintGC) { |
|
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|
3476 size_t new_mem_size = _virtual_space.committed_size(); |
|
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|
3477 size_t old_mem_size = new_mem_size + bytes; |
|
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|
3478 gclog_or_tty->print_cr("Shrinking %s from " SIZE_FORMAT "K to " SIZE_FORMAT "K", |
|
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|
3479 name(), old_mem_size/K, new_mem_size/K); |
|
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|
3480 } |
|
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|
3481 } |
| 0 | 3482 |
| 3483 void ConcurrentMarkSweepGeneration::shrink(size_t bytes) { | |
| 3484 assert_locked_or_safepoint(Heap_lock); | |
| 3485 size_t size = ReservedSpace::page_align_size_down(bytes); | |
|
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|
3486 // Only shrink if a compaction was done so that all the free space |
|
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|
3487 // in the generation is in a contiguous block at the end. |
|
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|
3488 if (size > 0 && did_compact()) { |
| 0 | 3489 shrink_by(size); |
| 3490 } | |
| 3491 } | |
| 3492 | |
| 3493 bool ConcurrentMarkSweepGeneration::grow_by(size_t bytes) { | |
| 3494 assert_locked_or_safepoint(Heap_lock); | |
| 3495 bool result = _virtual_space.expand_by(bytes); | |
| 3496 if (result) { | |
| 3497 size_t new_word_size = | |
| 3498 heap_word_size(_virtual_space.committed_size()); | |
| 3499 MemRegion mr(_cmsSpace->bottom(), new_word_size); | |
| 3500 _bts->resize(new_word_size); // resize the block offset shared array | |
| 3501 Universe::heap()->barrier_set()->resize_covered_region(mr); | |
| 3502 // Hmmmm... why doesn't CFLS::set_end verify locking? | |
| 3503 // This is quite ugly; FIX ME XXX | |
|
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|
3504 _cmsSpace->assert_locked(freelistLock()); |
| 0 | 3505 _cmsSpace->set_end((HeapWord*)_virtual_space.high()); |
| 3506 | |
| 3507 // update the space and generation capacity counters | |
| 3508 if (UsePerfData) { | |
| 3509 _space_counters->update_capacity(); | |
| 3510 _gen_counters->update_all(); | |
| 3511 } | |
| 3512 | |
| 3513 if (Verbose && PrintGC) { | |
| 3514 size_t new_mem_size = _virtual_space.committed_size(); | |
| 3515 size_t old_mem_size = new_mem_size - bytes; | |
|
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|
3516 gclog_or_tty->print_cr("Expanding %s from " SIZE_FORMAT "K by " SIZE_FORMAT "K to " SIZE_FORMAT "K", |
| 0 | 3517 name(), old_mem_size/K, bytes/K, new_mem_size/K); |
| 3518 } | |
| 3519 } | |
| 3520 return result; | |
| 3521 } | |
| 3522 | |
| 3523 bool ConcurrentMarkSweepGeneration::grow_to_reserved() { | |
| 3524 assert_locked_or_safepoint(Heap_lock); | |
| 3525 bool success = true; | |
| 3526 const size_t remaining_bytes = _virtual_space.uncommitted_size(); | |
| 3527 if (remaining_bytes > 0) { | |
| 3528 success = grow_by(remaining_bytes); | |
| 3529 DEBUG_ONLY(if (!success) warning("grow to reserved failed");) | |
| 3530 } | |
| 3531 return success; | |
| 3532 } | |
| 3533 | |
|
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|
3534 void ConcurrentMarkSweepGeneration::shrink_free_list_by(size_t bytes) { |
| 0 | 3535 assert_locked_or_safepoint(Heap_lock); |
| 3536 assert_lock_strong(freelistLock()); | |
|
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ebded0261dfc
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9152
diff
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|
3537 if (PrintGCDetails && Verbose) { |
|
ebded0261dfc
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diff
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|
3538 warning("Shrinking of CMS not yet implemented"); |
|
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|
3539 } |
| 0 | 3540 return; |
| 3541 } | |
| 3542 | |
| 3543 | |
| 3544 // Simple ctor/dtor wrapper for accounting & timer chores around concurrent | |
| 3545 // phases. | |
| 3546 class CMSPhaseAccounting: public StackObj { | |
| 3547 public: | |
| 3548 CMSPhaseAccounting(CMSCollector *collector, | |
| 3549 const char *phase, | |
|
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changeset
|
3550 const GCId gc_id, |
| 0 | 3551 bool print_cr = true); |
| 3552 ~CMSPhaseAccounting(); | |
| 3553 | |
| 3554 private: | |
| 3555 CMSCollector *_collector; | |
| 3556 const char *_phase; | |
| 3557 elapsedTimer _wallclock; | |
| 3558 bool _print_cr; | |
|
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|
3559 const GCId _gc_id; |
| 0 | 3560 |
| 3561 public: | |
| 3562 // Not MT-safe; so do not pass around these StackObj's | |
| 3563 // where they may be accessed by other threads. | |
| 3564 jlong wallclock_millis() { | |
| 3565 assert(_wallclock.is_active(), "Wall clock should not stop"); | |
| 3566 _wallclock.stop(); // to record time | |
| 3567 jlong ret = _wallclock.milliseconds(); | |
| 3568 _wallclock.start(); // restart | |
| 3569 return ret; | |
| 3570 } | |
| 3571 }; | |
| 3572 | |
| 3573 CMSPhaseAccounting::CMSPhaseAccounting(CMSCollector *collector, | |
| 3574 const char *phase, | |
|
20190
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|
3575 const GCId gc_id, |
| 0 | 3576 bool print_cr) : |
|
20190
0982ec23da03
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diff
changeset
|
3577 _collector(collector), _phase(phase), _print_cr(print_cr), _gc_id(gc_id) { |
| 0 | 3578 |
| 3579 if (PrintCMSStatistics != 0) { | |
| 3580 _collector->resetYields(); | |
| 3581 } | |
|
8740
62609ffa2fc6
8008684: CMS: concurrent phase start markers should always be printed
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8736
diff
changeset
|
3582 if (PrintGCDetails) { |
|
20190
0982ec23da03
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|
3583 gclog_or_tty->gclog_stamp(_gc_id); |
|
8740
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diff
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|
3584 gclog_or_tty->print_cr("[%s-concurrent-%s-start]", |
| 0 | 3585 _collector->cmsGen()->short_name(), _phase); |
| 3586 } | |
| 3587 _collector->resetTimer(); | |
| 3588 _wallclock.start(); | |
| 3589 _collector->startTimer(); | |
| 3590 } | |
| 3591 | |
| 3592 CMSPhaseAccounting::~CMSPhaseAccounting() { | |
| 3593 assert(_wallclock.is_active(), "Wall clock should not have stopped"); | |
| 3594 _collector->stopTimer(); | |
| 3595 _wallclock.stop(); | |
| 3596 if (PrintGCDetails) { | |
|
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|
3597 gclog_or_tty->gclog_stamp(_gc_id); |
| 0 | 3598 gclog_or_tty->print("[%s-concurrent-%s: %3.3f/%3.3f secs]", |
| 3599 _collector->cmsGen()->short_name(), | |
| 3600 _phase, _collector->timerValue(), _wallclock.seconds()); | |
| 3601 if (_print_cr) { | |
|
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|
3602 gclog_or_tty->cr(); |
| 0 | 3603 } |
| 3604 if (PrintCMSStatistics != 0) { | |
| 3605 gclog_or_tty->print_cr(" (CMS-concurrent-%s yielded %d times)", _phase, | |
| 3606 _collector->yields()); | |
| 3607 } | |
| 3608 } | |
| 3609 } | |
| 3610 | |
| 3611 // CMS work | |
| 3612 | |
| 11975 | 3613 // The common parts of CMSParInitialMarkTask and CMSParRemarkTask. |
| 3614 class CMSParMarkTask : public AbstractGangTask { | |
| 3615 protected: | |
| 3616 CMSCollector* _collector; | |
| 3617 int _n_workers; | |
| 3618 CMSParMarkTask(const char* name, CMSCollector* collector, int n_workers) : | |
| 3619 AbstractGangTask(name), | |
| 3620 _collector(collector), | |
| 3621 _n_workers(n_workers) {} | |
| 3622 // Work method in support of parallel rescan ... of young gen spaces | |
| 3623 void do_young_space_rescan(uint worker_id, OopsInGenClosure* cl, | |
| 3624 ContiguousSpace* space, | |
| 3625 HeapWord** chunk_array, size_t chunk_top); | |
| 3626 void work_on_young_gen_roots(uint worker_id, OopsInGenClosure* cl); | |
| 3627 }; | |
| 3628 | |
| 3629 // Parallel initial mark task | |
| 3630 class CMSParInitialMarkTask: public CMSParMarkTask { | |
| 3631 public: | |
| 3632 CMSParInitialMarkTask(CMSCollector* collector, int n_workers) : | |
| 3633 CMSParMarkTask("Scan roots and young gen for initial mark in parallel", | |
| 3634 collector, n_workers) {} | |
| 3635 void work(uint worker_id); | |
| 3636 }; | |
| 3637 | |
| 0 | 3638 // Checkpoint the roots into this generation from outside |
| 3639 // this generation. [Note this initial checkpoint need only | |
| 3640 // be approximate -- we'll do a catch up phase subsequently.] | |
| 3641 void CMSCollector::checkpointRootsInitial(bool asynch) { | |
| 3642 assert(_collectorState == InitialMarking, "Wrong collector state"); | |
| 3643 check_correct_thread_executing(); | |
|
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78542e2b5e35
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diff
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|
3644 TraceCMSMemoryManagerStats tms(_collectorState,GenCollectedHeap::heap()->gc_cause()); |
|
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diff
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|
3645 |
| 10405 | 3646 save_heap_summary(); |
| 3647 report_heap_summary(GCWhen::BeforeGC); | |
| 3648 | |
| 0 | 3649 ReferenceProcessor* rp = ref_processor(); |
| 3650 SpecializationStats::clear(); | |
| 3651 assert(_restart_addr == NULL, "Control point invariant"); | |
| 3652 if (asynch) { | |
| 3653 // acquire locks for subsequent manipulations | |
| 3654 MutexLockerEx x(bitMapLock(), | |
| 3655 Mutex::_no_safepoint_check_flag); | |
| 3656 checkpointRootsInitialWork(asynch); | |
|
3979
4dfb2df418f2
6484982: G1: process references during evacuation pauses
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3827
diff
changeset
|
3657 // enable ("weak") refs discovery |
|
4dfb2df418f2
6484982: G1: process references during evacuation pauses
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diff
changeset
|
3658 rp->enable_discovery(true /*verify_disabled*/, true /*check_no_refs*/); |
| 0 | 3659 _collectorState = Marking; |
| 3660 } else { | |
| 3661 // (Weak) Refs discovery: this is controlled from genCollectedHeap::do_collection | |
| 3662 // which recognizes if we are a CMS generation, and doesn't try to turn on | |
| 3663 // discovery; verify that they aren't meddling. | |
| 3664 assert(!rp->discovery_is_atomic(), | |
| 3665 "incorrect setting of discovery predicate"); | |
| 3666 assert(!rp->discovery_enabled(), "genCollectedHeap shouldn't control " | |
| 3667 "ref discovery for this generation kind"); | |
| 3668 // already have locks | |
| 3669 checkpointRootsInitialWork(asynch); | |
|
3979
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6484982: G1: process references during evacuation pauses
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3827
diff
changeset
|
3670 // now enable ("weak") refs discovery |
|
4dfb2df418f2
6484982: G1: process references during evacuation pauses
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3827
diff
changeset
|
3671 rp->enable_discovery(true /*verify_disabled*/, false /*verify_no_refs*/); |
| 0 | 3672 _collectorState = Marking; |
| 3673 } | |
| 3674 SpecializationStats::print(); | |
| 3675 } | |
| 3676 | |
| 3677 void CMSCollector::checkpointRootsInitialWork(bool asynch) { | |
| 3678 assert(SafepointSynchronize::is_at_safepoint(), "world should be stopped"); | |
| 3679 assert(_collectorState == InitialMarking, "just checking"); | |
| 3680 | |
| 3681 // If there has not been a GC[n-1] since last GC[n] cycle completed, | |
| 3682 // precede our marking with a collection of all | |
| 3683 // younger generations to keep floating garbage to a minimum. | |
| 3684 // XXX: we won't do this for now -- it's an optimization to be done later. | |
| 3685 | |
| 3686 // already have locks | |
| 3687 assert_lock_strong(bitMapLock()); | |
| 3688 assert(_markBitMap.isAllClear(), "was reset at end of previous cycle"); | |
| 3689 | |
| 3690 // Setup the verification and class unloading state for this | |
| 3691 // CMS collection cycle. | |
| 3692 setup_cms_unloading_and_verification_state(); | |
| 3693 | |
| 10405 | 3694 NOT_PRODUCT(GCTraceTime t("\ncheckpointRootsInitialWork", |
|
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|
3695 PrintGCDetails && Verbose, true, _gc_timer_cm, _gc_tracer_cm->gc_id());) |
| 0 | 3696 if (UseAdaptiveSizePolicy) { |
| 3697 size_policy()->checkpoint_roots_initial_begin(); | |
| 3698 } | |
| 3699 | |
| 3700 // Reset all the PLAB chunk arrays if necessary. | |
| 3701 if (_survivor_plab_array != NULL && !CMSPLABRecordAlways) { | |
| 3702 reset_survivor_plab_arrays(); | |
| 3703 } | |
| 3704 | |
| 3705 ResourceMark rm; | |
| 3706 HandleMark hm; | |
| 3707 | |
|
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|
3708 MarkRefsIntoClosure notOlder(_span, &_markBitMap); |
| 0 | 3709 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
| 3710 | |
| 3711 verify_work_stacks_empty(); | |
| 3712 verify_overflow_empty(); | |
| 3713 | |
| 3714 gch->ensure_parsability(false); // fill TLABs, but no need to retire them | |
| 3715 // Update the saved marks which may affect the root scans. | |
| 3716 gch->save_marks(); | |
| 3717 | |
| 3718 // weak reference processing has not started yet. | |
| 3719 ref_processor()->set_enqueuing_is_done(false); | |
| 3720 | |
|
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3721 // Need to remember all newly created CLDs, |
|
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3722 // so that we can guarantee that the remark finds them. |
|
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3723 ClassLoaderDataGraph::remember_new_clds(true); |
|
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3724 |
|
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3725 // Whenever a CLD is found, it will be claimed before proceeding to mark |
|
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3726 // the klasses. The claimed marks need to be cleared before marking starts. |
|
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3727 ClassLoaderDataGraph::clear_claimed_marks(); |
|
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3728 |
|
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|
3729 if (CMSPrintEdenSurvivorChunks) { |
|
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|
3730 print_eden_and_survivor_chunk_arrays(); |
|
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|
3731 } |
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|
3732 |
| 0 | 3733 { |
| 3734 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact;) | |
| 11975 | 3735 if (CMSParallelInitialMarkEnabled && CollectedHeap::use_parallel_gc_threads()) { |
| 3736 // The parallel version. | |
| 3737 FlexibleWorkGang* workers = gch->workers(); | |
| 3738 assert(workers != NULL, "Need parallel worker threads."); | |
| 3739 int n_workers = workers->active_workers(); | |
| 3740 CMSParInitialMarkTask tsk(this, n_workers); | |
| 3741 gch->set_par_threads(n_workers); | |
| 3742 initialize_sequential_subtasks_for_young_gen_rescan(n_workers); | |
| 3743 if (n_workers > 1) { | |
| 3744 GenCollectedHeap::StrongRootsScope srs(gch); | |
| 3745 workers->run_task(&tsk); | |
| 3746 } else { | |
| 3747 GenCollectedHeap::StrongRootsScope srs(gch); | |
| 3748 tsk.work(0); | |
| 3749 } | |
| 3750 gch->set_par_threads(0); | |
| 3751 } else { | |
| 3752 // The serial version. | |
|
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|
3753 CLDToOopClosure cld_closure(¬Older, true); |
| 11975 | 3754 gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel. |
|
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|
3755 gch->gen_process_roots(_cmsGen->level(), |
|
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3756 true, // younger gens are roots |
|
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|
3757 true, // activate StrongRootsScope |
|
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|
3758 GenCollectedHeap::ScanningOption(roots_scanning_options()), |
|
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|
3759 should_unload_classes(), |
|
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|
3760 ¬Older, |
|
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|
3761 NULL, |
|
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|
3762 &cld_closure); |
| 11975 | 3763 } |
| 0 | 3764 } |
| 3765 | |
| 3766 // Clear mod-union table; it will be dirtied in the prologue of | |
| 3767 // CMS generation per each younger generation collection. | |
| 3768 | |
| 3769 assert(_modUnionTable.isAllClear(), | |
| 3770 "Was cleared in most recent final checkpoint phase" | |
| 3771 " or no bits are set in the gc_prologue before the start of the next " | |
| 3772 "subsequent marking phase."); | |
| 3773 | |
|
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3774 assert(_ct->klass_rem_set()->mod_union_is_clear(), "Must be"); |
|
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|
3775 |
| 0 | 3776 // Save the end of the used_region of the constituent generations |
| 3777 // to be used to limit the extent of sweep in each generation. | |
| 3778 save_sweep_limits(); | |
| 3779 if (UseAdaptiveSizePolicy) { | |
| 3780 size_policy()->checkpoint_roots_initial_end(gch->gc_cause()); | |
| 3781 } | |
| 3782 verify_overflow_empty(); | |
| 3783 } | |
| 3784 | |
| 3785 bool CMSCollector::markFromRoots(bool asynch) { | |
| 3786 // we might be tempted to assert that: | |
| 3787 // assert(asynch == !SafepointSynchronize::is_at_safepoint(), | |
| 3788 // "inconsistent argument?"); | |
| 3789 // However that wouldn't be right, because it's possible that | |
| 3790 // a safepoint is indeed in progress as a younger generation | |
| 3791 // stop-the-world GC happens even as we mark in this generation. | |
| 3792 assert(_collectorState == Marking, "inconsistent state?"); | |
| 3793 check_correct_thread_executing(); | |
| 3794 verify_overflow_empty(); | |
| 3795 | |
| 3796 bool res; | |
| 3797 if (asynch) { | |
| 3798 | |
| 3799 // Start the timers for adaptive size policy for the concurrent phases | |
| 3800 // Do it here so that the foreground MS can use the concurrent | |
| 3801 // timer since a foreground MS might has the sweep done concurrently | |
| 3802 // or STW. | |
| 3803 if (UseAdaptiveSizePolicy) { | |
| 3804 size_policy()->concurrent_marking_begin(); | |
| 3805 } | |
| 3806 | |
| 3807 // Weak ref discovery note: We may be discovering weak | |
| 3808 // refs in this generation concurrent (but interleaved) with | |
| 3809 // weak ref discovery by a younger generation collector. | |
| 3810 | |
| 3811 CMSTokenSyncWithLocks ts(true, bitMapLock()); | |
| 3812 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
|
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|
3813 CMSPhaseAccounting pa(this, "mark", _gc_tracer_cm->gc_id(), !PrintGCDetails); |
| 0 | 3814 res = markFromRootsWork(asynch); |
| 3815 if (res) { | |
| 3816 _collectorState = Precleaning; | |
| 3817 } else { // We failed and a foreground collection wants to take over | |
| 3818 assert(_foregroundGCIsActive, "internal state inconsistency"); | |
| 3819 assert(_restart_addr == NULL, "foreground will restart from scratch"); | |
| 3820 if (PrintGCDetails) { | |
| 3821 gclog_or_tty->print_cr("bailing out to foreground collection"); | |
| 3822 } | |
| 3823 } | |
| 3824 if (UseAdaptiveSizePolicy) { | |
| 3825 size_policy()->concurrent_marking_end(); | |
| 3826 } | |
| 3827 } else { | |
| 3828 assert(SafepointSynchronize::is_at_safepoint(), | |
| 3829 "inconsistent with asynch == false"); | |
| 3830 if (UseAdaptiveSizePolicy) { | |
| 3831 size_policy()->ms_collection_marking_begin(); | |
| 3832 } | |
| 3833 // already have locks | |
| 3834 res = markFromRootsWork(asynch); | |
| 3835 _collectorState = FinalMarking; | |
| 3836 if (UseAdaptiveSizePolicy) { | |
| 3837 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 3838 size_policy()->ms_collection_marking_end(gch->gc_cause()); | |
| 3839 } | |
| 3840 } | |
| 3841 verify_overflow_empty(); | |
| 3842 return res; | |
| 3843 } | |
| 3844 | |
| 3845 bool CMSCollector::markFromRootsWork(bool asynch) { | |
| 3846 // iterate over marked bits in bit map, doing a full scan and mark | |
| 3847 // from these roots using the following algorithm: | |
| 3848 // . if oop is to the right of the current scan pointer, | |
| 3849 // mark corresponding bit (we'll process it later) | |
| 3850 // . else (oop is to left of current scan pointer) | |
| 3851 // push oop on marking stack | |
| 3852 // . drain the marking stack | |
| 3853 | |
| 3854 // Note that when we do a marking step we need to hold the | |
| 3855 // bit map lock -- recall that direct allocation (by mutators) | |
| 3856 // and promotion (by younger generation collectors) is also | |
| 3857 // marking the bit map. [the so-called allocate live policy.] | |
| 3858 // Because the implementation of bit map marking is not | |
| 3859 // robust wrt simultaneous marking of bits in the same word, | |
| 3860 // we need to make sure that there is no such interference | |
| 3861 // between concurrent such updates. | |
| 3862 | |
| 3863 // already have locks | |
| 3864 assert_lock_strong(bitMapLock()); | |
| 3865 | |
| 3866 verify_work_stacks_empty(); | |
| 3867 verify_overflow_empty(); | |
| 3868 bool result = false; | |
| 1284 | 3869 if (CMSConcurrentMTEnabled && ConcGCThreads > 0) { |
| 0 | 3870 result = do_marking_mt(asynch); |
| 3871 } else { | |
| 3872 result = do_marking_st(asynch); | |
| 3873 } | |
| 3874 return result; | |
| 3875 } | |
| 3876 | |
| 3877 // Forward decl | |
| 3878 class CMSConcMarkingTask; | |
| 3879 | |
| 3880 class CMSConcMarkingTerminator: public ParallelTaskTerminator { | |
| 3881 CMSCollector* _collector; | |
| 3882 CMSConcMarkingTask* _task; | |
|
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|
3883 public: |
| 0 | 3884 virtual void yield(); |
|
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|
3885 |
| 0 | 3886 // "n_threads" is the number of threads to be terminated. |
| 3887 // "queue_set" is a set of work queues of other threads. | |
| 3888 // "collector" is the CMS collector associated with this task terminator. | |
| 3889 // "yield" indicates whether we need the gang as a whole to yield. | |
|
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|
3890 CMSConcMarkingTerminator(int n_threads, TaskQueueSetSuper* queue_set, CMSCollector* collector) : |
| 0 | 3891 ParallelTaskTerminator(n_threads, queue_set), |
|
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|
3892 _collector(collector) { } |
|
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|
3893 |
|
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|
3894 void set_task(CMSConcMarkingTask* task) { |
|
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|
3895 _task = task; |
|
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|
3896 } |
|
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|
3897 }; |
|
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|
3898 |
|
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|
3899 class CMSConcMarkingTerminatorTerminator: public TerminatorTerminator { |
|
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|
3900 CMSConcMarkingTask* _task; |
|
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|
3901 public: |
|
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|
3902 bool should_exit_termination(); |
| 0 | 3903 void set_task(CMSConcMarkingTask* task) { |
| 3904 _task = task; | |
| 3905 } | |
| 3906 }; | |
| 3907 | |
| 3908 // MT Concurrent Marking Task | |
| 3909 class CMSConcMarkingTask: public YieldingFlexibleGangTask { | |
| 3910 CMSCollector* _collector; | |
| 3911 int _n_workers; // requested/desired # workers | |
| 3912 bool _asynch; | |
| 3913 bool _result; | |
| 3914 CompactibleFreeListSpace* _cms_space; | |
|
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|
3915 char _pad_front[64]; // padding to ... |
|
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|
3916 HeapWord* _global_finger; // ... avoid sharing cache line |
|
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|
3917 char _pad_back[64]; |
|
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|
3918 HeapWord* _restart_addr; |
| 0 | 3919 |
| 3920 // Exposed here for yielding support | |
| 3921 Mutex* const _bit_map_lock; | |
| 3922 | |
| 3923 // The per thread work queues, available here for stealing | |
| 3924 OopTaskQueueSet* _task_queues; | |
|
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|
3925 |
|
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|
3926 // Termination (and yielding) support |
| 0 | 3927 CMSConcMarkingTerminator _term; |
|
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|
3928 CMSConcMarkingTerminatorTerminator _term_term; |
| 0 | 3929 |
| 3930 public: | |
| 3931 CMSConcMarkingTask(CMSCollector* collector, | |
| 3932 CompactibleFreeListSpace* cms_space, | |
|
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|
3933 bool asynch, |
| 0 | 3934 YieldingFlexibleWorkGang* workers, |
| 3935 OopTaskQueueSet* task_queues): | |
| 3936 YieldingFlexibleGangTask("Concurrent marking done multi-threaded"), | |
| 3937 _collector(collector), | |
| 3938 _cms_space(cms_space), | |
|
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|
3939 _asynch(asynch), _n_workers(0), _result(true), |
|
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|
3940 _task_queues(task_queues), |
|
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|
3941 _term(_n_workers, task_queues, _collector), |
| 0 | 3942 _bit_map_lock(collector->bitMapLock()) |
| 3943 { | |
|
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|
3944 _requested_size = _n_workers; |
| 0 | 3945 _term.set_task(this); |
|
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|
3946 _term_term.set_task(this); |
|
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|
3947 _restart_addr = _global_finger = _cms_space->bottom(); |
| 0 | 3948 } |
| 3949 | |
| 3950 | |
| 3951 OopTaskQueueSet* task_queues() { return _task_queues; } | |
| 3952 | |
| 3953 OopTaskQueue* work_queue(int i) { return task_queues()->queue(i); } | |
| 3954 | |
| 3955 HeapWord** global_finger_addr() { return &_global_finger; } | |
| 3956 | |
| 3957 CMSConcMarkingTerminator* terminator() { return &_term; } | |
| 3958 | |
|
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|
3959 virtual void set_for_termination(int active_workers) { |
|
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|
3960 terminator()->reset_for_reuse(active_workers); |
|
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|
3961 } |
|
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|
3962 |
|
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|
3963 void work(uint worker_id); |
|
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|
3964 bool should_yield() { |
|
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|
3965 return ConcurrentMarkSweepThread::should_yield() |
|
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|
3966 && !_collector->foregroundGCIsActive() |
|
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|
3967 && _asynch; |
|
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|
3968 } |
| 0 | 3969 |
| 3970 virtual void coordinator_yield(); // stuff done by coordinator | |
| 3971 bool result() { return _result; } | |
| 3972 | |
| 3973 void reset(HeapWord* ra) { | |
|
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3974 assert(_global_finger >= _cms_space->end(), "Postcondition of ::work(i)"); |
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3975 _restart_addr = _global_finger = ra; |
| 0 | 3976 _term.reset_for_reuse(); |
| 3977 } | |
| 3978 | |
| 3979 static bool get_work_from_overflow_stack(CMSMarkStack* ovflw_stk, | |
| 3980 OopTaskQueue* work_q); | |
| 3981 | |
| 3982 private: | |
| 3983 void do_scan_and_mark(int i, CompactibleFreeListSpace* sp); | |
| 3984 void do_work_steal(int i); | |
| 3985 void bump_global_finger(HeapWord* f); | |
| 3986 }; | |
| 3987 | |
|
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3988 bool CMSConcMarkingTerminatorTerminator::should_exit_termination() { |
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3989 assert(_task != NULL, "Error"); |
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3990 return _task->yielding(); |
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3991 // Note that we do not need the disjunct || _task->should_yield() above |
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3992 // because we want terminating threads to yield only if the task |
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3993 // is already in the midst of yielding, which happens only after at least one |
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3994 // thread has yielded. |
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3995 } |
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3996 |
| 0 | 3997 void CMSConcMarkingTerminator::yield() { |
|
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3998 if (_task->should_yield()) { |
| 0 | 3999 _task->yield(); |
| 4000 } else { | |
| 4001 ParallelTaskTerminator::yield(); | |
| 4002 } | |
| 4003 } | |
| 4004 | |
| 4005 //////////////////////////////////////////////////////////////// | |
| 4006 // Concurrent Marking Algorithm Sketch | |
| 4007 //////////////////////////////////////////////////////////////// | |
| 4008 // Until all tasks exhausted (both spaces): | |
| 4009 // -- claim next available chunk | |
| 4010 // -- bump global finger via CAS | |
| 4011 // -- find first object that starts in this chunk | |
| 4012 // and start scanning bitmap from that position | |
| 4013 // -- scan marked objects for oops | |
| 4014 // -- CAS-mark target, and if successful: | |
| 4015 // . if target oop is above global finger (volatile read) | |
| 4016 // nothing to do | |
| 4017 // . if target oop is in chunk and above local finger | |
| 4018 // then nothing to do | |
| 4019 // . else push on work-queue | |
| 4020 // -- Deal with possible overflow issues: | |
| 4021 // . local work-queue overflow causes stuff to be pushed on | |
| 4022 // global (common) overflow queue | |
| 4023 // . always first empty local work queue | |
| 4024 // . then get a batch of oops from global work queue if any | |
| 4025 // . then do work stealing | |
| 4026 // -- When all tasks claimed (both spaces) | |
| 4027 // and local work queue empty, | |
| 4028 // then in a loop do: | |
| 4029 // . check global overflow stack; steal a batch of oops and trace | |
| 4030 // . try to steal from other threads oif GOS is empty | |
| 4031 // . if neither is available, offer termination | |
| 4032 // -- Terminate and return result | |
| 4033 // | |
|
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4034 void CMSConcMarkingTask::work(uint worker_id) { |
| 0 | 4035 elapsedTimer _timer; |
| 4036 ResourceMark rm; | |
| 4037 HandleMark hm; | |
| 4038 | |
| 4039 DEBUG_ONLY(_collector->verify_overflow_empty();) | |
| 4040 | |
| 4041 // Before we begin work, our work queue should be empty | |
|
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4042 assert(work_queue(worker_id)->size() == 0, "Expected to be empty"); |
| 0 | 4043 // Scan the bitmap covering _cms_space, tracing through grey objects. |
| 4044 _timer.start(); | |
|
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4045 do_scan_and_mark(worker_id, _cms_space); |
| 0 | 4046 _timer.stop(); |
| 4047 if (PrintCMSStatistics != 0) { | |
| 4048 gclog_or_tty->print_cr("Finished cms space scanning in %dth thread: %3.3f sec", | |
|
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4049 worker_id, _timer.seconds()); |
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4050 // XXX: need xxx/xxx type of notation, two timers |
| 0 | 4051 } |
| 4052 | |
| 4053 // ... do work stealing | |
| 4054 _timer.reset(); | |
| 4055 _timer.start(); | |
|
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4056 do_work_steal(worker_id); |
| 0 | 4057 _timer.stop(); |
| 4058 if (PrintCMSStatistics != 0) { | |
| 4059 gclog_or_tty->print_cr("Finished work stealing in %dth thread: %3.3f sec", | |
|
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4060 worker_id, _timer.seconds()); |
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4061 // XXX: need xxx/xxx type of notation, two timers |
| 0 | 4062 } |
| 4063 assert(_collector->_markStack.isEmpty(), "Should have been emptied"); | |
|
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4064 assert(work_queue(worker_id)->size() == 0, "Should have been emptied"); |
| 0 | 4065 // Note that under the current task protocol, the |
| 4066 // following assertion is true even of the spaces | |
| 4067 // expanded since the completion of the concurrent | |
| 4068 // marking. XXX This will likely change under a strict | |
| 4069 // ABORT semantics. | |
|
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4070 // After perm removal the comparison was changed to |
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4071 // greater than or equal to from strictly greater than. |
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4072 // Before perm removal the highest address sweep would |
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4073 // have been at the end of perm gen but now is at the |
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4074 // end of the tenured gen. |
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4075 assert(_global_finger >= _cms_space->end(), |
| 0 | 4076 "All tasks have been completed"); |
| 4077 DEBUG_ONLY(_collector->verify_overflow_empty();) | |
| 4078 } | |
| 4079 | |
| 4080 void CMSConcMarkingTask::bump_global_finger(HeapWord* f) { | |
| 4081 HeapWord* read = _global_finger; | |
| 4082 HeapWord* cur = read; | |
| 4083 while (f > read) { | |
| 4084 cur = read; | |
| 4085 read = (HeapWord*) Atomic::cmpxchg_ptr(f, &_global_finger, cur); | |
| 4086 if (cur == read) { | |
| 4087 // our cas succeeded | |
| 4088 assert(_global_finger >= f, "protocol consistency"); | |
| 4089 break; | |
| 4090 } | |
| 4091 } | |
| 4092 } | |
| 4093 | |
| 4094 // This is really inefficient, and should be redone by | |
| 4095 // using (not yet available) block-read and -write interfaces to the | |
| 4096 // stack and the work_queue. XXX FIX ME !!! | |
| 4097 bool CMSConcMarkingTask::get_work_from_overflow_stack(CMSMarkStack* ovflw_stk, | |
| 4098 OopTaskQueue* work_q) { | |
| 4099 // Fast lock-free check | |
| 4100 if (ovflw_stk->length() == 0) { | |
| 4101 return false; | |
| 4102 } | |
| 4103 assert(work_q->size() == 0, "Shouldn't steal"); | |
| 4104 MutexLockerEx ml(ovflw_stk->par_lock(), | |
| 4105 Mutex::_no_safepoint_check_flag); | |
| 4106 // Grab up to 1/4 the size of the work queue | |
|
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4107 size_t num = MIN2((size_t)(work_q->max_elems() - work_q->size())/4, |
| 0 | 4108 (size_t)ParGCDesiredObjsFromOverflowList); |
| 4109 num = MIN2(num, ovflw_stk->length()); | |
| 4110 for (int i = (int) num; i > 0; i--) { | |
| 4111 oop cur = ovflw_stk->pop(); | |
| 4112 assert(cur != NULL, "Counted wrong?"); | |
| 4113 work_q->push(cur); | |
| 4114 } | |
| 4115 return num > 0; | |
| 4116 } | |
| 4117 | |
| 4118 void CMSConcMarkingTask::do_scan_and_mark(int i, CompactibleFreeListSpace* sp) { | |
| 4119 SequentialSubTasksDone* pst = sp->conc_par_seq_tasks(); | |
| 4120 int n_tasks = pst->n_tasks(); | |
| 4121 // We allow that there may be no tasks to do here because | |
| 4122 // we are restarting after a stack overflow. | |
|
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4123 assert(pst->valid() || n_tasks == 0, "Uninitialized use?"); |
|
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4124 uint nth_task = 0; |
| 0 | 4125 |
|
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4126 HeapWord* aligned_start = sp->bottom(); |
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4127 if (sp->used_region().contains(_restart_addr)) { |
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4128 // Align down to a card boundary for the start of 0th task |
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4129 // for this space. |
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4130 aligned_start = |
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4131 (HeapWord*)align_size_down((uintptr_t)_restart_addr, |
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4132 CardTableModRefBS::card_size); |
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4133 } |
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4134 |
| 0 | 4135 size_t chunk_size = sp->marking_task_size(); |
| 4136 while (!pst->is_task_claimed(/* reference */ nth_task)) { | |
| 4137 // Having claimed the nth task in this space, | |
| 4138 // compute the chunk that it corresponds to: | |
|
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4139 MemRegion span = MemRegion(aligned_start + nth_task*chunk_size, |
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4140 aligned_start + (nth_task+1)*chunk_size); |
| 0 | 4141 // Try and bump the global finger via a CAS; |
| 4142 // note that we need to do the global finger bump | |
| 4143 // _before_ taking the intersection below, because | |
| 4144 // the task corresponding to that region will be | |
| 4145 // deemed done even if the used_region() expands | |
| 4146 // because of allocation -- as it almost certainly will | |
| 4147 // during start-up while the threads yield in the | |
| 4148 // closure below. | |
| 4149 HeapWord* finger = span.end(); | |
| 4150 bump_global_finger(finger); // atomically | |
| 4151 // There are null tasks here corresponding to chunks | |
| 4152 // beyond the "top" address of the space. | |
| 4153 span = span.intersection(sp->used_region()); | |
| 4154 if (!span.is_empty()) { // Non-null task | |
|
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4155 HeapWord* prev_obj; |
|
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4156 assert(!span.contains(_restart_addr) || nth_task == 0, |
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4157 "Inconsistency"); |
|
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4158 if (nth_task == 0) { |
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4159 // For the 0th task, we'll not need to compute a block_start. |
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4160 if (span.contains(_restart_addr)) { |
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4161 // In the case of a restart because of stack overflow, |
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4162 // we might additionally skip a chunk prefix. |
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4163 prev_obj = _restart_addr; |
| 0 | 4164 } else { |
|
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4165 prev_obj = span.start(); |
|
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4166 } |
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4167 } else { |
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4168 // We want to skip the first object because |
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4169 // the protocol is to scan any object in its entirety |
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4170 // that _starts_ in this span; a fortiori, any |
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4171 // object starting in an earlier span is scanned |
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4172 // as part of an earlier claimed task. |
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4173 // Below we use the "careful" version of block_start |
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4174 // so we do not try to navigate uninitialized objects. |
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4175 prev_obj = sp->block_start_careful(span.start()); |
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4176 // Below we use a variant of block_size that uses the |
|
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4177 // Printezis bits to avoid waiting for allocated |
|
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4178 // objects to become initialized/parsable. |
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4179 while (prev_obj < span.start()) { |
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4180 size_t sz = sp->block_size_no_stall(prev_obj, _collector); |
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4181 if (sz > 0) { |
|
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4182 prev_obj += sz; |
|
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4183 } else { |
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4184 // In this case we may end up doing a bit of redundant |
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4185 // scanning, but that appears unavoidable, short of |
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4186 // locking the free list locks; see bug 6324141. |
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4187 break; |
|
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4188 } |
| 0 | 4189 } |
| 4190 } | |
| 4191 if (prev_obj < span.end()) { | |
| 4192 MemRegion my_span = MemRegion(prev_obj, span.end()); | |
| 4193 // Do the marking work within a non-empty span -- | |
| 4194 // the last argument to the constructor indicates whether the | |
| 4195 // iteration should be incremental with periodic yields. | |
| 4196 Par_MarkFromRootsClosure cl(this, _collector, my_span, | |
| 4197 &_collector->_markBitMap, | |
| 4198 work_queue(i), | |
| 4199 &_collector->_markStack, | |
| 4200 _asynch); | |
| 4201 _collector->_markBitMap.iterate(&cl, my_span.start(), my_span.end()); | |
| 4202 } // else nothing to do for this task | |
| 4203 } // else nothing to do for this task | |
| 4204 } | |
| 4205 // We'd be tempted to assert here that since there are no | |
| 4206 // more tasks left to claim in this space, the global_finger | |
| 4207 // must exceed space->top() and a fortiori space->end(). However, | |
| 4208 // that would not quite be correct because the bumping of | |
| 4209 // global_finger occurs strictly after the claiming of a task, | |
| 4210 // so by the time we reach here the global finger may not yet | |
| 4211 // have been bumped up by the thread that claimed the last | |
| 4212 // task. | |
| 4213 pst->all_tasks_completed(); | |
| 4214 } | |
| 4215 | |
|
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4216 class Par_ConcMarkingClosure: public MetadataAwareOopClosure { |
|
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4217 private: |
|
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4218 CMSCollector* _collector; |
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4219 CMSConcMarkingTask* _task; |
| 0 | 4220 MemRegion _span; |
| 4221 CMSBitMap* _bit_map; | |
| 4222 CMSMarkStack* _overflow_stack; | |
| 4223 OopTaskQueue* _work_queue; | |
|
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4224 protected: |
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4225 DO_OOP_WORK_DEFN |
| 0 | 4226 public: |
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4227 Par_ConcMarkingClosure(CMSCollector* collector, CMSConcMarkingTask* task, OopTaskQueue* work_queue, |
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4228 CMSBitMap* bit_map, CMSMarkStack* overflow_stack): |
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4229 MetadataAwareOopClosure(collector->ref_processor()), |
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4230 _collector(collector), |
|
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4231 _task(task), |
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4232 _span(collector->_span), |
| 0 | 4233 _work_queue(work_queue), |
| 4234 _bit_map(bit_map), | |
| 935 | 4235 _overflow_stack(overflow_stack) |
| 4236 { } | |
|
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4237 virtual void do_oop(oop* p); |
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4238 virtual void do_oop(narrowOop* p); |
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4239 |
| 0 | 4240 void trim_queue(size_t max); |
| 4241 void handle_stack_overflow(HeapWord* lost); | |
|
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4242 void do_yield_check() { |
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4243 if (_task->should_yield()) { |
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4244 _task->yield(); |
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4245 } |
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4246 } |
| 0 | 4247 }; |
| 4248 | |
|
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4249 // Grey object scanning during work stealing phase -- |
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4250 // the salient assumption here is that any references |
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4251 // that are in these stolen objects being scanned must |
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4252 // already have been initialized (else they would not have |
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4253 // been published), so we do not need to check for |
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4254 // uninitialized objects before pushing here. |
|
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4255 void Par_ConcMarkingClosure::do_oop(oop obj) { |
|
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4256 assert(obj->is_oop_or_null(true), "expected an oop or NULL"); |
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4257 HeapWord* addr = (HeapWord*)obj; |
| 0 | 4258 // Check if oop points into the CMS generation |
| 4259 // and is not marked | |
| 4260 if (_span.contains(addr) && !_bit_map->isMarked(addr)) { | |
| 4261 // a white object ... | |
| 4262 // If we manage to "claim" the object, by being the | |
| 4263 // first thread to mark it, then we push it on our | |
| 4264 // marking stack | |
| 4265 if (_bit_map->par_mark(addr)) { // ... now grey | |
| 4266 // push on work queue (grey set) | |
| 4267 bool simulate_overflow = false; | |
| 4268 NOT_PRODUCT( | |
| 4269 if (CMSMarkStackOverflowALot && | |
| 4270 _collector->simulate_overflow()) { | |
| 4271 // simulate a stack overflow | |
| 4272 simulate_overflow = true; | |
| 4273 } | |
| 4274 ) | |
| 4275 if (simulate_overflow || | |
|
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4276 !(_work_queue->push(obj) || _overflow_stack->par_push(obj))) { |
| 0 | 4277 // stack overflow |
| 4278 if (PrintCMSStatistics != 0) { | |
| 4279 gclog_or_tty->print_cr("CMS marking stack overflow (benign) at " | |
| 4280 SIZE_FORMAT, _overflow_stack->capacity()); | |
| 4281 } | |
| 4282 // We cannot assert that the overflow stack is full because | |
| 4283 // it may have been emptied since. | |
| 4284 assert(simulate_overflow || | |
| 4285 _work_queue->size() == _work_queue->max_elems(), | |
| 4286 "Else push should have succeeded"); | |
| 4287 handle_stack_overflow(addr); | |
| 4288 } | |
| 4289 } // Else, some other thread got there first | |
|
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4290 do_yield_check(); |
| 0 | 4291 } |
| 4292 } | |
| 4293 | |
|
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4294 void Par_ConcMarkingClosure::do_oop(oop* p) { Par_ConcMarkingClosure::do_oop_work(p); } |
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4295 void Par_ConcMarkingClosure::do_oop(narrowOop* p) { Par_ConcMarkingClosure::do_oop_work(p); } |
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4296 |
| 0 | 4297 void Par_ConcMarkingClosure::trim_queue(size_t max) { |
| 4298 while (_work_queue->size() > max) { | |
| 4299 oop new_oop; | |
| 4300 if (_work_queue->pop_local(new_oop)) { | |
| 4301 assert(new_oop->is_oop(), "Should be an oop"); | |
| 4302 assert(_bit_map->isMarked((HeapWord*)new_oop), "Grey object"); | |
| 4303 assert(_span.contains((HeapWord*)new_oop), "Not in span"); | |
| 4304 new_oop->oop_iterate(this); // do_oop() above | |
|
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4305 do_yield_check(); |
| 0 | 4306 } |
| 4307 } | |
| 4308 } | |
| 4309 | |
| 4310 // Upon stack overflow, we discard (part of) the stack, | |
| 4311 // remembering the least address amongst those discarded | |
| 4312 // in CMSCollector's _restart_address. | |
| 4313 void Par_ConcMarkingClosure::handle_stack_overflow(HeapWord* lost) { | |
| 4314 // We need to do this under a mutex to prevent other | |
|
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4315 // workers from interfering with the work done below. |
| 0 | 4316 MutexLockerEx ml(_overflow_stack->par_lock(), |
| 4317 Mutex::_no_safepoint_check_flag); | |
| 4318 // Remember the least grey address discarded | |
| 4319 HeapWord* ra = (HeapWord*)_overflow_stack->least_value(lost); | |
| 4320 _collector->lower_restart_addr(ra); | |
| 4321 _overflow_stack->reset(); // discard stack contents | |
| 4322 _overflow_stack->expand(); // expand the stack if possible | |
| 4323 } | |
| 4324 | |
| 4325 | |
| 4326 void CMSConcMarkingTask::do_work_steal(int i) { | |
| 4327 OopTaskQueue* work_q = work_queue(i); | |
| 4328 oop obj_to_scan; | |
| 4329 CMSBitMap* bm = &(_collector->_markBitMap); | |
| 4330 CMSMarkStack* ovflw = &(_collector->_markStack); | |
| 4331 int* seed = _collector->hash_seed(i); | |
|
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4332 Par_ConcMarkingClosure cl(_collector, this, work_q, bm, ovflw); |
| 0 | 4333 while (true) { |
| 4334 cl.trim_queue(0); | |
| 4335 assert(work_q->size() == 0, "Should have been emptied above"); | |
| 4336 if (get_work_from_overflow_stack(ovflw, work_q)) { | |
| 4337 // Can't assert below because the work obtained from the | |
| 4338 // overflow stack may already have been stolen from us. | |
| 4339 // assert(work_q->size() > 0, "Work from overflow stack"); | |
| 4340 continue; | |
| 4341 } else if (task_queues()->steal(i, seed, /* reference */ obj_to_scan)) { | |
| 4342 assert(obj_to_scan->is_oop(), "Should be an oop"); | |
| 4343 assert(bm->isMarked((HeapWord*)obj_to_scan), "Grey object"); | |
| 4344 obj_to_scan->oop_iterate(&cl); | |
|
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4345 } else if (terminator()->offer_termination(&_term_term)) { |
| 0 | 4346 assert(work_q->size() == 0, "Impossible!"); |
| 4347 break; | |
|
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4348 } else if (yielding() || should_yield()) { |
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|
4349 yield(); |
| 0 | 4350 } |
| 4351 } | |
| 4352 } | |
| 4353 | |
| 4354 // This is run by the CMS (coordinator) thread. | |
| 4355 void CMSConcMarkingTask::coordinator_yield() { | |
| 4356 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 4357 "CMS thread should hold CMS token"); | |
| 4358 // First give up the locks, then yield, then re-lock | |
| 4359 // We should probably use a constructor/destructor idiom to | |
| 4360 // do this unlock/lock or modify the MutexUnlocker class to | |
| 4361 // serve our purpose. XXX | |
| 4362 assert_lock_strong(_bit_map_lock); | |
| 4363 _bit_map_lock->unlock(); | |
| 4364 ConcurrentMarkSweepThread::desynchronize(true); | |
| 4365 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 4366 _collector->stopTimer(); | |
| 4367 if (PrintCMSStatistics != 0) { | |
| 4368 _collector->incrementYields(); | |
| 4369 } | |
| 4370 _collector->icms_wait(); | |
| 4371 | |
| 4372 // It is possible for whichever thread initiated the yield request | |
| 4373 // not to get a chance to wake up and take the bitmap lock between | |
| 4374 // this thread releasing it and reacquiring it. So, while the | |
| 4375 // should_yield() flag is on, let's sleep for a bit to give the | |
| 4376 // other thread a chance to wake up. The limit imposed on the number | |
| 4377 // of iterations is defensive, to avoid any unforseen circumstances | |
| 4378 // putting us into an infinite loop. Since it's always been this | |
| 4379 // (coordinator_yield()) method that was observed to cause the | |
| 4380 // problem, we are using a parameter (CMSCoordinatorYieldSleepCount) | |
| 4381 // which is by default non-zero. For the other seven methods that | |
| 4382 // also perform the yield operation, as are using a different | |
| 4383 // parameter (CMSYieldSleepCount) which is by default zero. This way we | |
| 4384 // can enable the sleeping for those methods too, if necessary. | |
| 4385 // See 6442774. | |
| 4386 // | |
| 4387 // We really need to reconsider the synchronization between the GC | |
| 4388 // thread and the yield-requesting threads in the future and we | |
| 4389 // should really use wait/notify, which is the recommended | |
| 4390 // way of doing this type of interaction. Additionally, we should | |
| 4391 // consolidate the eight methods that do the yield operation and they | |
| 4392 // are almost identical into one for better maintenability and | |
| 4393 // readability. See 6445193. | |
| 4394 // | |
| 4395 // Tony 2006.06.29 | |
| 4396 for (unsigned i = 0; i < CMSCoordinatorYieldSleepCount && | |
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4397 ConcurrentMarkSweepThread::should_yield() && |
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4398 !CMSCollector::foregroundGCIsActive(); ++i) { |
| 0 | 4399 os::sleep(Thread::current(), 1, false); |
| 4400 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 4401 } | |
| 4402 | |
| 4403 ConcurrentMarkSweepThread::synchronize(true); | |
| 4404 _bit_map_lock->lock_without_safepoint_check(); | |
| 4405 _collector->startTimer(); | |
| 4406 } | |
| 4407 | |
| 4408 bool CMSCollector::do_marking_mt(bool asynch) { | |
| 1284 | 4409 assert(ConcGCThreads > 0 && conc_workers() != NULL, "precondition"); |
|
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4410 int num_workers = AdaptiveSizePolicy::calc_active_conc_workers( |
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4411 conc_workers()->total_workers(), |
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4412 conc_workers()->active_workers(), |
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4413 Threads::number_of_non_daemon_threads()); |
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4414 conc_workers()->set_active_workers(num_workers); |
| 0 | 4415 |
| 4416 CompactibleFreeListSpace* cms_space = _cmsGen->cmsSpace(); | |
| 4417 | |
|
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4418 CMSConcMarkingTask tsk(this, |
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4419 cms_space, |
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4420 asynch, |
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4421 conc_workers(), |
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4422 task_queues()); |
| 0 | 4423 |
| 4424 // Since the actual number of workers we get may be different | |
| 4425 // from the number we requested above, do we need to do anything different | |
| 4426 // below? In particular, may be we need to subclass the SequantialSubTasksDone | |
| 4427 // class?? XXX | |
| 4428 cms_space ->initialize_sequential_subtasks_for_marking(num_workers); | |
| 4429 | |
| 4430 // Refs discovery is already non-atomic. | |
| 4431 assert(!ref_processor()->discovery_is_atomic(), "Should be non-atomic"); | |
|
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4432 assert(ref_processor()->discovery_is_mt(), "Discovery should be MT"); |
| 0 | 4433 conc_workers()->start_task(&tsk); |
| 4434 while (tsk.yielded()) { | |
| 4435 tsk.coordinator_yield(); | |
| 4436 conc_workers()->continue_task(&tsk); | |
| 4437 } | |
| 4438 // If the task was aborted, _restart_addr will be non-NULL | |
| 4439 assert(tsk.completed() || _restart_addr != NULL, "Inconsistency"); | |
| 4440 while (_restart_addr != NULL) { | |
| 4441 // XXX For now we do not make use of ABORTED state and have not | |
| 4442 // yet implemented the right abort semantics (even in the original | |
| 4443 // single-threaded CMS case). That needs some more investigation | |
| 4444 // and is deferred for now; see CR# TBF. 07252005YSR. XXX | |
| 4445 assert(!CMSAbortSemantics || tsk.aborted(), "Inconsistency"); | |
| 4446 // If _restart_addr is non-NULL, a marking stack overflow | |
| 605 | 4447 // occurred; we need to do a fresh marking iteration from the |
| 0 | 4448 // indicated restart address. |
| 4449 if (_foregroundGCIsActive && asynch) { | |
| 4450 // We may be running into repeated stack overflows, having | |
| 4451 // reached the limit of the stack size, while making very | |
| 4452 // slow forward progress. It may be best to bail out and | |
| 4453 // let the foreground collector do its job. | |
| 4454 // Clear _restart_addr, so that foreground GC | |
| 4455 // works from scratch. This avoids the headache of | |
| 4456 // a "rescan" which would otherwise be needed because | |
| 4457 // of the dirty mod union table & card table. | |
| 4458 _restart_addr = NULL; | |
| 4459 return false; | |
| 4460 } | |
| 4461 // Adjust the task to restart from _restart_addr | |
| 4462 tsk.reset(_restart_addr); | |
| 4463 cms_space ->initialize_sequential_subtasks_for_marking(num_workers, | |
| 4464 _restart_addr); | |
| 4465 _restart_addr = NULL; | |
| 4466 // Get the workers going again | |
| 4467 conc_workers()->start_task(&tsk); | |
| 4468 while (tsk.yielded()) { | |
| 4469 tsk.coordinator_yield(); | |
| 4470 conc_workers()->continue_task(&tsk); | |
| 4471 } | |
| 4472 } | |
| 4473 assert(tsk.completed(), "Inconsistency"); | |
| 4474 assert(tsk.result() == true, "Inconsistency"); | |
| 4475 return true; | |
| 4476 } | |
| 4477 | |
| 4478 bool CMSCollector::do_marking_st(bool asynch) { | |
| 4479 ResourceMark rm; | |
| 4480 HandleMark hm; | |
| 4481 | |
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4482 // Temporarily make refs discovery single threaded (non-MT) |
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4483 ReferenceProcessorMTDiscoveryMutator rp_mut_discovery(ref_processor(), false); |
| 0 | 4484 MarkFromRootsClosure markFromRootsClosure(this, _span, &_markBitMap, |
|
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4485 &_markStack, CMSYield && asynch); |
| 0 | 4486 // the last argument to iterate indicates whether the iteration |
| 4487 // should be incremental with periodic yields. | |
| 4488 _markBitMap.iterate(&markFromRootsClosure); | |
| 4489 // If _restart_addr is non-NULL, a marking stack overflow | |
| 605 | 4490 // occurred; we need to do a fresh iteration from the |
| 0 | 4491 // indicated restart address. |
| 4492 while (_restart_addr != NULL) { | |
| 4493 if (_foregroundGCIsActive && asynch) { | |
| 4494 // We may be running into repeated stack overflows, having | |
| 4495 // reached the limit of the stack size, while making very | |
| 4496 // slow forward progress. It may be best to bail out and | |
| 4497 // let the foreground collector do its job. | |
| 4498 // Clear _restart_addr, so that foreground GC | |
| 4499 // works from scratch. This avoids the headache of | |
| 4500 // a "rescan" which would otherwise be needed because | |
| 4501 // of the dirty mod union table & card table. | |
| 4502 _restart_addr = NULL; | |
| 4503 return false; // indicating failure to complete marking | |
| 4504 } | |
| 4505 // Deal with stack overflow: | |
| 4506 // we restart marking from _restart_addr | |
| 4507 HeapWord* ra = _restart_addr; | |
| 4508 markFromRootsClosure.reset(ra); | |
| 4509 _restart_addr = NULL; | |
| 4510 _markBitMap.iterate(&markFromRootsClosure, ra, _span.end()); | |
| 4511 } | |
| 4512 return true; | |
| 4513 } | |
| 4514 | |
| 4515 void CMSCollector::preclean() { | |
| 4516 check_correct_thread_executing(); | |
| 4517 assert(Thread::current()->is_ConcurrentGC_thread(), "Wrong thread"); | |
| 4518 verify_work_stacks_empty(); | |
| 4519 verify_overflow_empty(); | |
| 4520 _abort_preclean = false; | |
| 4521 if (CMSPrecleaningEnabled) { | |
|
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|
4522 if (!CMSEdenChunksRecordAlways) { |
|
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|
4523 _eden_chunk_index = 0; |
|
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diff
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|
4524 } |
| 0 | 4525 size_t used = get_eden_used(); |
| 4526 size_t capacity = get_eden_capacity(); | |
| 4527 // Don't start sampling unless we will get sufficiently | |
| 4528 // many samples. | |
| 4529 if (used < (capacity/(CMSScheduleRemarkSamplingRatio * 100) | |
| 4530 * CMSScheduleRemarkEdenPenetration)) { | |
| 4531 _start_sampling = true; | |
| 4532 } else { | |
| 4533 _start_sampling = false; | |
| 4534 } | |
| 4535 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
|
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|
4536 CMSPhaseAccounting pa(this, "preclean", _gc_tracer_cm->gc_id(), !PrintGCDetails); |
| 0 | 4537 preclean_work(CMSPrecleanRefLists1, CMSPrecleanSurvivors1); |
| 4538 } | |
| 4539 CMSTokenSync x(true); // is cms thread | |
| 4540 if (CMSPrecleaningEnabled) { | |
| 4541 sample_eden(); | |
| 4542 _collectorState = AbortablePreclean; | |
| 4543 } else { | |
| 4544 _collectorState = FinalMarking; | |
| 4545 } | |
| 4546 verify_work_stacks_empty(); | |
| 4547 verify_overflow_empty(); | |
| 4548 } | |
| 4549 | |
| 4550 // Try and schedule the remark such that young gen | |
| 4551 // occupancy is CMSScheduleRemarkEdenPenetration %. | |
| 4552 void CMSCollector::abortable_preclean() { | |
| 4553 check_correct_thread_executing(); | |
| 4554 assert(CMSPrecleaningEnabled, "Inconsistent control state"); | |
| 4555 assert(_collectorState == AbortablePreclean, "Inconsistent control state"); | |
| 4556 | |
| 4557 // If Eden's current occupancy is below this threshold, | |
| 4558 // immediately schedule the remark; else preclean | |
| 4559 // past the next scavenge in an effort to | |
| 4560 // schedule the pause as described avove. By choosing | |
| 4561 // CMSScheduleRemarkEdenSizeThreshold >= max eden size | |
| 4562 // we will never do an actual abortable preclean cycle. | |
| 4563 if (get_eden_used() > CMSScheduleRemarkEdenSizeThreshold) { | |
| 4564 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
|
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|
4565 CMSPhaseAccounting pa(this, "abortable-preclean", _gc_tracer_cm->gc_id(), !PrintGCDetails); |
| 0 | 4566 // We need more smarts in the abortable preclean |
| 4567 // loop below to deal with cases where allocation | |
| 4568 // in young gen is very very slow, and our precleaning | |
| 4569 // is running a losing race against a horde of | |
| 4570 // mutators intent on flooding us with CMS updates | |
| 4571 // (dirty cards). | |
| 4572 // One, admittedly dumb, strategy is to give up | |
| 4573 // after a certain number of abortable precleaning loops | |
| 4574 // or after a certain maximum time. We want to make | |
| 4575 // this smarter in the next iteration. | |
| 4576 // XXX FIX ME!!! YSR | |
| 4577 size_t loops = 0, workdone = 0, cumworkdone = 0, waited = 0; | |
| 4578 while (!(should_abort_preclean() || | |
| 4579 ConcurrentMarkSweepThread::should_terminate())) { | |
| 4580 workdone = preclean_work(CMSPrecleanRefLists2, CMSPrecleanSurvivors2); | |
| 4581 cumworkdone += workdone; | |
| 4582 loops++; | |
| 4583 // Voluntarily terminate abortable preclean phase if we have | |
| 4584 // been at it for too long. | |
| 4585 if ((CMSMaxAbortablePrecleanLoops != 0) && | |
| 4586 loops >= CMSMaxAbortablePrecleanLoops) { | |
| 4587 if (PrintGCDetails) { | |
| 4588 gclog_or_tty->print(" CMS: abort preclean due to loops "); | |
| 4589 } | |
| 4590 break; | |
| 4591 } | |
| 4592 if (pa.wallclock_millis() > CMSMaxAbortablePrecleanTime) { | |
| 4593 if (PrintGCDetails) { | |
| 4594 gclog_or_tty->print(" CMS: abort preclean due to time "); | |
| 4595 } | |
| 4596 break; | |
| 4597 } | |
| 4598 // If we are doing little work each iteration, we should | |
| 4599 // take a short break. | |
| 4600 if (workdone < CMSAbortablePrecleanMinWorkPerIteration) { | |
| 4601 // Sleep for some time, waiting for work to accumulate | |
| 4602 stopTimer(); | |
| 4603 cmsThread()->wait_on_cms_lock(CMSAbortablePrecleanWaitMillis); | |
| 4604 startTimer(); | |
| 4605 waited++; | |
| 4606 } | |
| 4607 } | |
| 4608 if (PrintCMSStatistics > 0) { | |
| 4609 gclog_or_tty->print(" [%d iterations, %d waits, %d cards)] ", | |
| 4610 loops, waited, cumworkdone); | |
| 4611 } | |
| 4612 } | |
| 4613 CMSTokenSync x(true); // is cms thread | |
| 4614 if (_collectorState != Idling) { | |
| 4615 assert(_collectorState == AbortablePreclean, | |
| 4616 "Spontaneous state transition?"); | |
| 4617 _collectorState = FinalMarking; | |
| 4618 } // Else, a foreground collection completed this CMS cycle. | |
| 4619 return; | |
| 4620 } | |
| 4621 | |
| 4622 // Respond to an Eden sampling opportunity | |
| 4623 void CMSCollector::sample_eden() { | |
| 4624 // Make sure a young gc cannot sneak in between our | |
| 4625 // reading and recording of a sample. | |
| 4626 assert(Thread::current()->is_ConcurrentGC_thread(), | |
| 4627 "Only the cms thread may collect Eden samples"); | |
| 4628 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 4629 "Should collect samples while holding CMS token"); | |
| 4630 if (!_start_sampling) { | |
| 4631 return; | |
| 4632 } | |
|
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|
4633 // When CMSEdenChunksRecordAlways is true, the eden chunk array |
|
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|
4634 // is populated by the young generation. |
|
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diff
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|
4635 if (_eden_chunk_array != NULL && !CMSEdenChunksRecordAlways) { |
| 0 | 4636 if (_eden_chunk_index < _eden_chunk_capacity) { |
| 4637 _eden_chunk_array[_eden_chunk_index] = *_top_addr; // take sample | |
| 4638 assert(_eden_chunk_array[_eden_chunk_index] <= *_end_addr, | |
| 4639 "Unexpected state of Eden"); | |
| 4640 // We'd like to check that what we just sampled is an oop-start address; | |
| 4641 // however, we cannot do that here since the object may not yet have been | |
| 4642 // initialized. So we'll instead do the check when we _use_ this sample | |
| 4643 // later. | |
| 4644 if (_eden_chunk_index == 0 || | |
| 4645 (pointer_delta(_eden_chunk_array[_eden_chunk_index], | |
| 4646 _eden_chunk_array[_eden_chunk_index-1]) | |
| 4647 >= CMSSamplingGrain)) { | |
| 4648 _eden_chunk_index++; // commit sample | |
| 4649 } | |
| 4650 } | |
| 4651 } | |
| 4652 if ((_collectorState == AbortablePreclean) && !_abort_preclean) { | |
| 4653 size_t used = get_eden_used(); | |
| 4654 size_t capacity = get_eden_capacity(); | |
| 4655 assert(used <= capacity, "Unexpected state of Eden"); | |
| 4656 if (used > (capacity/100 * CMSScheduleRemarkEdenPenetration)) { | |
| 4657 _abort_preclean = true; | |
| 4658 } | |
| 4659 } | |
| 4660 } | |
| 4661 | |
| 4662 | |
| 4663 size_t CMSCollector::preclean_work(bool clean_refs, bool clean_survivor) { | |
| 4664 assert(_collectorState == Precleaning || | |
| 4665 _collectorState == AbortablePreclean, "incorrect state"); | |
| 4666 ResourceMark rm; | |
| 4667 HandleMark hm; | |
|
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|
4668 |
|
92da084fefc9
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2365
diff
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|
4669 // Precleaning is currently not MT but the reference processor |
|
92da084fefc9
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diff
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|
4670 // may be set for MT. Disable it temporarily here. |
|
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diff
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|
4671 ReferenceProcessor* rp = ref_processor(); |
|
92da084fefc9
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diff
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|
4672 ReferenceProcessorMTDiscoveryMutator rp_mut_discovery(rp, false); |
|
92da084fefc9
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|
4673 |
| 0 | 4674 // Do one pass of scrubbing the discovered reference lists |
| 4675 // to remove any reference objects with strongly-reachable | |
| 4676 // referents. | |
| 4677 if (clean_refs) { | |
| 4678 CMSPrecleanRefsYieldClosure yield_cl(this); | |
| 4679 assert(rp->span().equals(_span), "Spans should be equal"); | |
| 4680 CMSKeepAliveClosure keep_alive(this, _span, &_markBitMap, | |
|
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|
4681 &_markStack, true /* preclean */); |
| 0 | 4682 CMSDrainMarkingStackClosure complete_trace(this, |
|
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|
4683 _span, &_markBitMap, &_markStack, |
|
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diff
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|
4684 &keep_alive, true /* preclean */); |
| 0 | 4685 |
| 4686 // We don't want this step to interfere with a young | |
| 4687 // collection because we don't want to take CPU | |
| 4688 // or memory bandwidth away from the young GC threads | |
| 4689 // (which may be as many as there are CPUs). | |
| 4690 // Note that we don't need to protect ourselves from | |
| 4691 // interference with mutators because they can't | |
| 4692 // manipulate the discovered reference lists nor affect | |
| 4693 // the computed reachability of the referents, the | |
| 4694 // only properties manipulated by the precleaning | |
| 4695 // of these reference lists. | |
| 4696 stopTimer(); | |
| 4697 CMSTokenSyncWithLocks x(true /* is cms thread */, | |
| 4698 bitMapLock()); | |
| 4699 startTimer(); | |
| 4700 sample_eden(); | |
| 935 | 4701 |
| 0 | 4702 // The following will yield to allow foreground |
| 4703 // collection to proceed promptly. XXX YSR: | |
| 4704 // The code in this method may need further | |
| 4705 // tweaking for better performance and some restructuring | |
| 4706 // for cleaner interfaces. | |
| 10405 | 4707 GCTimer *gc_timer = NULL; // Currently not tracing concurrent phases |
| 0 | 4708 rp->preclean_discovered_references( |
| 10405 | 4709 rp->is_alive_non_header(), &keep_alive, &complete_trace, &yield_cl, |
|
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diff
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|
4710 gc_timer, _gc_tracer_cm->gc_id()); |
| 0 | 4711 } |
| 4712 | |
| 4713 if (clean_survivor) { // preclean the active survivor space(s) | |
| 4714 assert(_young_gen->kind() == Generation::DefNew || | |
| 4715 _young_gen->kind() == Generation::ParNew || | |
| 4716 _young_gen->kind() == Generation::ASParNew, | |
| 4717 "incorrect type for cast"); | |
| 4718 DefNewGeneration* dng = (DefNewGeneration*)_young_gen; | |
| 4719 PushAndMarkClosure pam_cl(this, _span, ref_processor(), | |
| 4720 &_markBitMap, &_modUnionTable, | |
|
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diff
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|
4721 &_markStack, true /* precleaning phase */); |
| 0 | 4722 stopTimer(); |
| 4723 CMSTokenSyncWithLocks ts(true /* is cms thread */, | |
| 4724 bitMapLock()); | |
| 4725 startTimer(); | |
| 4726 unsigned int before_count = | |
| 4727 GenCollectedHeap::heap()->total_collections(); | |
| 4728 SurvivorSpacePrecleanClosure | |
| 4729 sss_cl(this, _span, &_markBitMap, &_markStack, | |
| 4730 &pam_cl, before_count, CMSYield); | |
| 4731 dng->from()->object_iterate_careful(&sss_cl); | |
| 4732 dng->to()->object_iterate_careful(&sss_cl); | |
| 4733 } | |
| 4734 MarkRefsIntoAndScanClosure | |
| 4735 mrias_cl(_span, ref_processor(), &_markBitMap, &_modUnionTable, | |
|
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|
4736 &_markStack, this, CMSYield, |
| 0 | 4737 true /* precleaning phase */); |
| 4738 // CAUTION: The following closure has persistent state that may need to | |
| 4739 // be reset upon a decrease in the sequence of addresses it | |
| 4740 // processes. | |
| 4741 ScanMarkedObjectsAgainCarefullyClosure | |
| 4742 smoac_cl(this, _span, | |
|
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|
4743 &_markBitMap, &_markStack, &mrias_cl, CMSYield); |
| 0 | 4744 |
| 4745 // Preclean dirty cards in ModUnionTable and CardTable using | |
| 4746 // appropriate convergence criterion; | |
| 4747 // repeat CMSPrecleanIter times unless we find that | |
| 4748 // we are losing. | |
| 4749 assert(CMSPrecleanIter < 10, "CMSPrecleanIter is too large"); | |
| 4750 assert(CMSPrecleanNumerator < CMSPrecleanDenominator, | |
| 4751 "Bad convergence multiplier"); | |
| 4752 assert(CMSPrecleanThreshold >= 100, | |
| 4753 "Unreasonably low CMSPrecleanThreshold"); | |
| 4754 | |
| 4755 size_t numIter, cumNumCards, lastNumCards, curNumCards; | |
| 4756 for (numIter = 0, cumNumCards = lastNumCards = curNumCards = 0; | |
| 4757 numIter < CMSPrecleanIter; | |
| 4758 numIter++, lastNumCards = curNumCards, cumNumCards += curNumCards) { | |
| 4759 curNumCards = preclean_mod_union_table(_cmsGen, &smoac_cl); | |
| 4760 if (Verbose && PrintGCDetails) { | |
| 4761 gclog_or_tty->print(" (modUnionTable: %d cards)", curNumCards); | |
| 4762 } | |
| 4763 // Either there are very few dirty cards, so re-mark | |
| 4764 // pause will be small anyway, or our pre-cleaning isn't | |
| 4765 // that much faster than the rate at which cards are being | |
| 4766 // dirtied, so we might as well stop and re-mark since | |
| 4767 // precleaning won't improve our re-mark time by much. | |
| 4768 if (curNumCards <= CMSPrecleanThreshold || | |
| 4769 (numIter > 0 && | |
| 4770 (curNumCards * CMSPrecleanDenominator > | |
| 4771 lastNumCards * CMSPrecleanNumerator))) { | |
| 4772 numIter++; | |
| 4773 cumNumCards += curNumCards; | |
| 4774 break; | |
| 4775 } | |
| 4776 } | |
|
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|
4777 |
|
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|
4778 preclean_klasses(&mrias_cl, _cmsGen->freelistLock()); |
|
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diff
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|
4779 |
| 0 | 4780 curNumCards = preclean_card_table(_cmsGen, &smoac_cl); |
| 4781 cumNumCards += curNumCards; | |
| 4782 if (PrintGCDetails && PrintCMSStatistics != 0) { | |
| 4783 gclog_or_tty->print_cr(" (cardTable: %d cards, re-scanned %d cards, %d iterations)", | |
| 4784 curNumCards, cumNumCards, numIter); | |
| 4785 } | |
| 4786 return cumNumCards; // as a measure of useful work done | |
| 4787 } | |
| 4788 | |
| 4789 // PRECLEANING NOTES: | |
| 4790 // Precleaning involves: | |
| 4791 // . reading the bits of the modUnionTable and clearing the set bits. | |
| 4792 // . For the cards corresponding to the set bits, we scan the | |
| 4793 // objects on those cards. This means we need the free_list_lock | |
| 4794 // so that we can safely iterate over the CMS space when scanning | |
| 4795 // for oops. | |
| 4796 // . When we scan the objects, we'll be both reading and setting | |
| 4797 // marks in the marking bit map, so we'll need the marking bit map. | |
| 4798 // . For protecting _collector_state transitions, we take the CGC_lock. | |
| 4799 // Note that any races in the reading of of card table entries by the | |
| 4800 // CMS thread on the one hand and the clearing of those entries by the | |
| 4801 // VM thread or the setting of those entries by the mutator threads on the | |
| 4802 // other are quite benign. However, for efficiency it makes sense to keep | |
| 4803 // the VM thread from racing with the CMS thread while the latter is | |
| 4804 // dirty card info to the modUnionTable. We therefore also use the | |
| 4805 // CGC_lock to protect the reading of the card table and the mod union | |
| 4806 // table by the CM thread. | |
| 4807 // . We run concurrently with mutator updates, so scanning | |
| 4808 // needs to be done carefully -- we should not try to scan | |
| 4809 // potentially uninitialized objects. | |
| 4810 // | |
| 4811 // Locking strategy: While holding the CGC_lock, we scan over and | |
| 4812 // reset a maximal dirty range of the mod union / card tables, then lock | |
| 4813 // the free_list_lock and bitmap lock to do a full marking, then | |
| 4814 // release these locks; and repeat the cycle. This allows for a | |
| 4815 // certain amount of fairness in the sharing of these locks between | |
| 4816 // the CMS collector on the one hand, and the VM thread and the | |
| 4817 // mutators on the other. | |
| 4818 | |
| 4819 // NOTE: preclean_mod_union_table() and preclean_card_table() | |
| 4820 // further below are largely identical; if you need to modify | |
| 4821 // one of these methods, please check the other method too. | |
| 4822 | |
| 4823 size_t CMSCollector::preclean_mod_union_table( | |
| 4824 ConcurrentMarkSweepGeneration* gen, | |
| 4825 ScanMarkedObjectsAgainCarefullyClosure* cl) { | |
| 4826 verify_work_stacks_empty(); | |
| 4827 verify_overflow_empty(); | |
| 4828 | |
| 4829 // strategy: starting with the first card, accumulate contiguous | |
| 4830 // ranges of dirty cards; clear these cards, then scan the region | |
| 4831 // covered by these cards. | |
| 4832 | |
| 4833 // Since all of the MUT is committed ahead, we can just use | |
| 4834 // that, in case the generations expand while we are precleaning. | |
| 4835 // It might also be fine to just use the committed part of the | |
| 4836 // generation, but we might potentially miss cards when the | |
| 4837 // generation is rapidly expanding while we are in the midst | |
| 4838 // of precleaning. | |
| 4839 HeapWord* startAddr = gen->reserved().start(); | |
| 4840 HeapWord* endAddr = gen->reserved().end(); | |
| 4841 | |
| 4842 cl->setFreelistLock(gen->freelistLock()); // needed for yielding | |
| 4843 | |
| 4844 size_t numDirtyCards, cumNumDirtyCards; | |
| 4845 HeapWord *nextAddr, *lastAddr; | |
| 4846 for (cumNumDirtyCards = numDirtyCards = 0, | |
| 4847 nextAddr = lastAddr = startAddr; | |
| 4848 nextAddr < endAddr; | |
| 4849 nextAddr = lastAddr, cumNumDirtyCards += numDirtyCards) { | |
| 4850 | |
| 4851 ResourceMark rm; | |
| 4852 HandleMark hm; | |
| 4853 | |
| 4854 MemRegion dirtyRegion; | |
| 4855 { | |
| 4856 stopTimer(); | |
| 935 | 4857 // Potential yield point |
| 0 | 4858 CMSTokenSync ts(true); |
| 4859 startTimer(); | |
| 4860 sample_eden(); | |
| 4861 // Get dirty region starting at nextOffset (inclusive), | |
| 4862 // simultaneously clearing it. | |
| 4863 dirtyRegion = | |
| 4864 _modUnionTable.getAndClearMarkedRegion(nextAddr, endAddr); | |
| 4865 assert(dirtyRegion.start() >= nextAddr, | |
| 4866 "returned region inconsistent?"); | |
| 4867 } | |
| 4868 // Remember where the next search should begin. | |
| 4869 // The returned region (if non-empty) is a right open interval, | |
| 4870 // so lastOffset is obtained from the right end of that | |
| 4871 // interval. | |
| 4872 lastAddr = dirtyRegion.end(); | |
| 4873 // Should do something more transparent and less hacky XXX | |
| 4874 numDirtyCards = | |
| 4875 _modUnionTable.heapWordDiffToOffsetDiff(dirtyRegion.word_size()); | |
| 4876 | |
| 4877 // We'll scan the cards in the dirty region (with periodic | |
| 4878 // yields for foreground GC as needed). | |
| 4879 if (!dirtyRegion.is_empty()) { | |
| 4880 assert(numDirtyCards > 0, "consistency check"); | |
| 4881 HeapWord* stop_point = NULL; | |
|
453
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|
4882 stopTimer(); |
| 935 | 4883 // Potential yield point |
|
453
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diff
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|
4884 CMSTokenSyncWithLocks ts(true, gen->freelistLock(), |
|
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452
diff
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|
4885 bitMapLock()); |
|
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diff
changeset
|
4886 startTimer(); |
| 0 | 4887 { |
| 4888 verify_work_stacks_empty(); | |
| 4889 verify_overflow_empty(); | |
| 4890 sample_eden(); | |
| 4891 stop_point = | |
| 4892 gen->cmsSpace()->object_iterate_careful_m(dirtyRegion, cl); | |
| 4893 } | |
| 4894 if (stop_point != NULL) { | |
| 4895 // The careful iteration stopped early either because it found an | |
| 4896 // uninitialized object, or because we were in the midst of an | |
| 4897 // "abortable preclean", which should now be aborted. Redirty | |
| 4898 // the bits corresponding to the partially-scanned or unscanned | |
| 4899 // cards. We'll either restart at the next block boundary or | |
| 4900 // abort the preclean. | |
|
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4901 assert((_collectorState == AbortablePreclean && should_abort_preclean()), |
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4902 "Should only be AbortablePreclean."); |
| 0 | 4903 _modUnionTable.mark_range(MemRegion(stop_point, dirtyRegion.end())); |
| 4904 if (should_abort_preclean()) { | |
| 4905 break; // out of preclean loop | |
| 4906 } else { | |
| 4907 // Compute the next address at which preclean should pick up; | |
| 4908 // might need bitMapLock in order to read P-bits. | |
| 4909 lastAddr = next_card_start_after_block(stop_point); | |
| 4910 } | |
| 4911 } | |
| 4912 } else { | |
| 4913 assert(lastAddr == endAddr, "consistency check"); | |
| 4914 assert(numDirtyCards == 0, "consistency check"); | |
| 4915 break; | |
| 4916 } | |
| 4917 } | |
| 4918 verify_work_stacks_empty(); | |
| 4919 verify_overflow_empty(); | |
| 4920 return cumNumDirtyCards; | |
| 4921 } | |
| 4922 | |
| 4923 // NOTE: preclean_mod_union_table() above and preclean_card_table() | |
| 4924 // below are largely identical; if you need to modify | |
| 4925 // one of these methods, please check the other method too. | |
| 4926 | |
| 4927 size_t CMSCollector::preclean_card_table(ConcurrentMarkSweepGeneration* gen, | |
| 4928 ScanMarkedObjectsAgainCarefullyClosure* cl) { | |
| 4929 // strategy: it's similar to precleamModUnionTable above, in that | |
| 4930 // we accumulate contiguous ranges of dirty cards, mark these cards | |
| 4931 // precleaned, then scan the region covered by these cards. | |
| 4932 HeapWord* endAddr = (HeapWord*)(gen->_virtual_space.high()); | |
| 4933 HeapWord* startAddr = (HeapWord*)(gen->_virtual_space.low()); | |
| 4934 | |
| 4935 cl->setFreelistLock(gen->freelistLock()); // needed for yielding | |
| 4936 | |
| 4937 size_t numDirtyCards, cumNumDirtyCards; | |
| 4938 HeapWord *lastAddr, *nextAddr; | |
| 4939 | |
| 4940 for (cumNumDirtyCards = numDirtyCards = 0, | |
| 4941 nextAddr = lastAddr = startAddr; | |
| 4942 nextAddr < endAddr; | |
| 4943 nextAddr = lastAddr, cumNumDirtyCards += numDirtyCards) { | |
| 4944 | |
| 4945 ResourceMark rm; | |
| 4946 HandleMark hm; | |
| 4947 | |
| 4948 MemRegion dirtyRegion; | |
| 4949 { | |
| 4950 // See comments in "Precleaning notes" above on why we | |
| 4951 // do this locking. XXX Could the locking overheads be | |
| 4952 // too high when dirty cards are sparse? [I don't think so.] | |
| 4953 stopTimer(); | |
| 4954 CMSTokenSync x(true); // is cms thread | |
| 4955 startTimer(); | |
| 4956 sample_eden(); | |
| 4957 // Get and clear dirty region from card table | |
|
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4958 dirtyRegion = _ct->ct_bs()->dirty_card_range_after_reset( |
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4959 MemRegion(nextAddr, endAddr), |
|
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4960 true, |
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4961 CardTableModRefBS::precleaned_card_val()); |
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4962 |
| 0 | 4963 assert(dirtyRegion.start() >= nextAddr, |
| 4964 "returned region inconsistent?"); | |
| 4965 } | |
| 4966 lastAddr = dirtyRegion.end(); | |
| 4967 numDirtyCards = | |
| 4968 dirtyRegion.word_size()/CardTableModRefBS::card_size_in_words; | |
| 4969 | |
| 4970 if (!dirtyRegion.is_empty()) { | |
| 4971 stopTimer(); | |
| 4972 CMSTokenSyncWithLocks ts(true, gen->freelistLock(), bitMapLock()); | |
| 4973 startTimer(); | |
| 4974 sample_eden(); | |
| 4975 verify_work_stacks_empty(); | |
| 4976 verify_overflow_empty(); | |
| 4977 HeapWord* stop_point = | |
| 4978 gen->cmsSpace()->object_iterate_careful_m(dirtyRegion, cl); | |
| 4979 if (stop_point != NULL) { | |
|
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4980 assert((_collectorState == AbortablePreclean && should_abort_preclean()), |
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4981 "Should only be AbortablePreclean."); |
| 0 | 4982 _ct->ct_bs()->invalidate(MemRegion(stop_point, dirtyRegion.end())); |
| 4983 if (should_abort_preclean()) { | |
| 4984 break; // out of preclean loop | |
| 4985 } else { | |
| 4986 // Compute the next address at which preclean should pick up. | |
| 4987 lastAddr = next_card_start_after_block(stop_point); | |
| 4988 } | |
| 4989 } | |
| 4990 } else { | |
| 4991 break; | |
| 4992 } | |
| 4993 } | |
| 4994 verify_work_stacks_empty(); | |
| 4995 verify_overflow_empty(); | |
| 4996 return cumNumDirtyCards; | |
| 4997 } | |
| 4998 | |
|
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4999 class PrecleanKlassClosure : public KlassClosure { |
|
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5000 KlassToOopClosure _cm_klass_closure; |
|
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5001 public: |
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5002 PrecleanKlassClosure(OopClosure* oop_closure) : _cm_klass_closure(oop_closure) {} |
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5003 void do_klass(Klass* k) { |
|
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5004 if (k->has_accumulated_modified_oops()) { |
|
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5005 k->clear_accumulated_modified_oops(); |
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5006 |
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5007 _cm_klass_closure.do_klass(k); |
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5008 } |
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5009 } |
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5010 }; |
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5011 |
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5012 // The freelist lock is needed to prevent asserts, is it really needed? |
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5013 void CMSCollector::preclean_klasses(MarkRefsIntoAndScanClosure* cl, Mutex* freelistLock) { |
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5014 |
|
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5015 cl->set_freelistLock(freelistLock); |
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5016 |
|
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5017 CMSTokenSyncWithLocks ts(true, freelistLock, bitMapLock()); |
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5018 |
|
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|
5019 // SSS: Add equivalent to ScanMarkedObjectsAgainCarefullyClosure::do_yield_check and should_abort_preclean? |
|
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5020 // SSS: We should probably check if precleaning should be aborted, at suitable intervals? |
|
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5021 PrecleanKlassClosure preclean_klass_closure(cl); |
|
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5022 ClassLoaderDataGraph::classes_do(&preclean_klass_closure); |
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5023 |
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5024 verify_work_stacks_empty(); |
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5025 verify_overflow_empty(); |
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5026 } |
|
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|
5027 |
| 0 | 5028 void CMSCollector::checkpointRootsFinal(bool asynch, |
| 5029 bool clear_all_soft_refs, bool init_mark_was_synchronous) { | |
| 5030 assert(_collectorState == FinalMarking, "incorrect state transition?"); | |
| 5031 check_correct_thread_executing(); | |
| 5032 // world is stopped at this checkpoint | |
| 5033 assert(SafepointSynchronize::is_at_safepoint(), | |
| 5034 "world should be stopped"); | |
|
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5035 TraceCMSMemoryManagerStats tms(_collectorState,GenCollectedHeap::heap()->gc_cause()); |
|
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5036 |
| 0 | 5037 verify_work_stacks_empty(); |
| 5038 verify_overflow_empty(); | |
| 5039 | |
| 5040 SpecializationStats::clear(); | |
| 5041 if (PrintGCDetails) { | |
| 5042 gclog_or_tty->print("[YG occupancy: "SIZE_FORMAT" K ("SIZE_FORMAT" K)]", | |
| 5043 _young_gen->used() / K, | |
| 5044 _young_gen->capacity() / K); | |
| 5045 } | |
| 5046 if (asynch) { | |
| 5047 if (CMSScavengeBeforeRemark) { | |
| 5048 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 5049 // Temporarily set flag to false, GCH->do_collection will | |
| 5050 // expect it to be false and set to true | |
| 5051 FlagSetting fl(gch->_is_gc_active, false); | |
| 10405 | 5052 NOT_PRODUCT(GCTraceTime t("Scavenge-Before-Remark", |
|
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|
5053 PrintGCDetails && Verbose, true, _gc_timer_cm, _gc_tracer_cm->gc_id());) |
| 0 | 5054 int level = _cmsGen->level() - 1; |
| 5055 if (level >= 0) { | |
| 5056 gch->do_collection(true, // full (i.e. force, see below) | |
| 5057 false, // !clear_all_soft_refs | |
| 5058 0, // size | |
| 5059 false, // is_tlab | |
| 5060 level // max_level | |
| 5061 ); | |
| 5062 } | |
| 5063 } | |
| 5064 FreelistLocker x(this); | |
| 5065 MutexLockerEx y(bitMapLock(), | |
| 5066 Mutex::_no_safepoint_check_flag); | |
| 5067 assert(!init_mark_was_synchronous, "but that's impossible!"); | |
| 5068 checkpointRootsFinalWork(asynch, clear_all_soft_refs, false); | |
| 5069 } else { | |
| 5070 // already have all the locks | |
| 5071 checkpointRootsFinalWork(asynch, clear_all_soft_refs, | |
| 5072 init_mark_was_synchronous); | |
| 5073 } | |
| 5074 verify_work_stacks_empty(); | |
| 5075 verify_overflow_empty(); | |
| 5076 SpecializationStats::print(); | |
| 5077 } | |
| 5078 | |
| 5079 void CMSCollector::checkpointRootsFinalWork(bool asynch, | |
| 5080 bool clear_all_soft_refs, bool init_mark_was_synchronous) { | |
| 5081 | |
|
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|
5082 NOT_PRODUCT(GCTraceTime tr("checkpointRootsFinalWork", PrintGCDetails, false, _gc_timer_cm, _gc_tracer_cm->gc_id());) |
| 0 | 5083 |
| 5084 assert(haveFreelistLocks(), "must have free list locks"); | |
| 5085 assert_lock_strong(bitMapLock()); | |
| 5086 | |
| 5087 if (UseAdaptiveSizePolicy) { | |
| 5088 size_policy()->checkpoint_roots_final_begin(); | |
| 5089 } | |
| 5090 | |
| 5091 ResourceMark rm; | |
| 5092 HandleMark hm; | |
| 5093 | |
| 5094 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 5095 | |
|
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|
5096 if (should_unload_classes()) { |
| 0 | 5097 CodeCache::gc_prologue(); |
| 5098 } | |
| 5099 assert(haveFreelistLocks(), "must have free list locks"); | |
| 5100 assert_lock_strong(bitMapLock()); | |
| 5101 | |
| 5102 if (!init_mark_was_synchronous) { | |
| 5103 // We might assume that we need not fill TLAB's when | |
| 5104 // CMSScavengeBeforeRemark is set, because we may have just done | |
| 5105 // a scavenge which would have filled all TLAB's -- and besides | |
| 5106 // Eden would be empty. This however may not always be the case -- | |
| 5107 // for instance although we asked for a scavenge, it may not have | |
| 5108 // happened because of a JNI critical section. We probably need | |
| 5109 // a policy for deciding whether we can in that case wait until | |
| 5110 // the critical section releases and then do the remark following | |
| 5111 // the scavenge, and skip it here. In the absence of that policy, | |
| 5112 // or of an indication of whether the scavenge did indeed occur, | |
| 5113 // we cannot rely on TLAB's having been filled and must do | |
| 5114 // so here just in case a scavenge did not happen. | |
| 5115 gch->ensure_parsability(false); // fill TLAB's, but no need to retire them | |
| 5116 // Update the saved marks which may affect the root scans. | |
| 5117 gch->save_marks(); | |
| 5118 | |
|
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5119 if (CMSPrintEdenSurvivorChunks) { |
|
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5120 print_eden_and_survivor_chunk_arrays(); |
|
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5121 } |
|
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|
5122 |
| 0 | 5123 { |
| 5124 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact;) | |
| 5125 | |
| 5126 // Note on the role of the mod union table: | |
| 5127 // Since the marker in "markFromRoots" marks concurrently with | |
| 5128 // mutators, it is possible for some reachable objects not to have been | |
| 5129 // scanned. For instance, an only reference to an object A was | |
| 5130 // placed in object B after the marker scanned B. Unless B is rescanned, | |
| 5131 // A would be collected. Such updates to references in marked objects | |
| 5132 // are detected via the mod union table which is the set of all cards | |
| 5133 // dirtied since the first checkpoint in this GC cycle and prior to | |
| 5134 // the most recent young generation GC, minus those cleaned up by the | |
| 5135 // concurrent precleaning. | |
|
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|
5136 if (CMSParallelRemarkEnabled && CollectedHeap::use_parallel_gc_threads()) { |
|
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|
5137 GCTraceTime t("Rescan (parallel) ", PrintGCDetails, false, _gc_timer_cm, _gc_tracer_cm->gc_id()); |
| 0 | 5138 do_remark_parallel(); |
| 5139 } else { | |
| 10405 | 5140 GCTraceTime t("Rescan (non-parallel) ", PrintGCDetails, false, |
|
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|
5141 _gc_timer_cm, _gc_tracer_cm->gc_id()); |
| 0 | 5142 do_remark_non_parallel(); |
| 5143 } | |
| 5144 } | |
| 5145 } else { | |
| 5146 assert(!asynch, "Can't have init_mark_was_synchronous in asynch mode"); | |
| 5147 // The initial mark was stop-world, so there's no rescanning to | |
| 5148 // do; go straight on to the next step below. | |
| 5149 } | |
| 5150 verify_work_stacks_empty(); | |
| 5151 verify_overflow_empty(); | |
| 5152 | |
| 5153 { | |
|
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|
5154 NOT_PRODUCT(GCTraceTime ts("refProcessingWork", PrintGCDetails, false, _gc_timer_cm, _gc_tracer_cm->gc_id());) |
| 0 | 5155 refProcessingWork(asynch, clear_all_soft_refs); |
| 5156 } | |
| 5157 verify_work_stacks_empty(); | |
| 5158 verify_overflow_empty(); | |
| 5159 | |
|
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|
5160 if (should_unload_classes()) { |
| 0 | 5161 CodeCache::gc_epilogue(); |
| 5162 } | |
|
2147
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|
5163 JvmtiExport::gc_epilogue(); |
| 0 | 5164 |
| 5165 // If we encountered any (marking stack / work queue) overflow | |
| 5166 // events during the current CMS cycle, take appropriate | |
| 5167 // remedial measures, where possible, so as to try and avoid | |
| 5168 // recurrence of that condition. | |
| 5169 assert(_markStack.isEmpty(), "No grey objects"); | |
| 5170 size_t ser_ovflw = _ser_pmc_remark_ovflw + _ser_pmc_preclean_ovflw + | |
|
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5171 _ser_kac_ovflw + _ser_kac_preclean_ovflw; |
| 0 | 5172 if (ser_ovflw > 0) { |
| 5173 if (PrintCMSStatistics != 0) { | |
| 5174 gclog_or_tty->print_cr("Marking stack overflow (benign) " | |
|
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5175 "(pmc_pc="SIZE_FORMAT", pmc_rm="SIZE_FORMAT", kac="SIZE_FORMAT |
|
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5176 ", kac_preclean="SIZE_FORMAT")", |
| 0 | 5177 _ser_pmc_preclean_ovflw, _ser_pmc_remark_ovflw, |
|
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|
5178 _ser_kac_ovflw, _ser_kac_preclean_ovflw); |
| 0 | 5179 } |
| 5180 _markStack.expand(); | |
| 5181 _ser_pmc_remark_ovflw = 0; | |
| 5182 _ser_pmc_preclean_ovflw = 0; | |
|
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|
5183 _ser_kac_preclean_ovflw = 0; |
| 0 | 5184 _ser_kac_ovflw = 0; |
| 5185 } | |
| 5186 if (_par_pmc_remark_ovflw > 0 || _par_kac_ovflw > 0) { | |
| 5187 if (PrintCMSStatistics != 0) { | |
| 5188 gclog_or_tty->print_cr("Work queue overflow (benign) " | |
| 5189 "(pmc_rm="SIZE_FORMAT", kac="SIZE_FORMAT")", | |
| 5190 _par_pmc_remark_ovflw, _par_kac_ovflw); | |
| 5191 } | |
| 5192 _par_pmc_remark_ovflw = 0; | |
| 5193 _par_kac_ovflw = 0; | |
| 5194 } | |
| 5195 if (PrintCMSStatistics != 0) { | |
| 5196 if (_markStack._hit_limit > 0) { | |
| 5197 gclog_or_tty->print_cr(" (benign) Hit max stack size limit ("SIZE_FORMAT")", | |
| 5198 _markStack._hit_limit); | |
| 5199 } | |
| 5200 if (_markStack._failed_double > 0) { | |
| 5201 gclog_or_tty->print_cr(" (benign) Failed stack doubling ("SIZE_FORMAT")," | |
| 5202 " current capacity "SIZE_FORMAT, | |
| 5203 _markStack._failed_double, | |
| 5204 _markStack.capacity()); | |
| 5205 } | |
| 5206 } | |
| 5207 _markStack._hit_limit = 0; | |
| 5208 _markStack._failed_double = 0; | |
| 5209 | |
| 5210 if ((VerifyAfterGC || VerifyDuringGC) && | |
| 5211 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
| 5212 verify_after_remark(); | |
| 5213 } | |
| 5214 | |
| 10405 | 5215 _gc_tracer_cm->report_object_count_after_gc(&_is_alive_closure); |
| 5216 | |
| 0 | 5217 // Change under the freelistLocks. |
| 5218 _collectorState = Sweeping; | |
| 5219 // Call isAllClear() under bitMapLock | |
|
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|
5220 assert(_modUnionTable.isAllClear(), |
|
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|
5221 "Should be clear by end of the final marking"); |
|
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|
5222 assert(_ct->klass_rem_set()->mod_union_is_clear(), |
|
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|
5223 "Should be clear by end of the final marking"); |
| 0 | 5224 if (UseAdaptiveSizePolicy) { |
| 5225 size_policy()->checkpoint_roots_final_end(gch->gc_cause()); | |
| 5226 } | |
| 5227 } | |
| 5228 | |
| 11975 | 5229 void CMSParInitialMarkTask::work(uint worker_id) { |
| 5230 elapsedTimer _timer; | |
| 5231 ResourceMark rm; | |
| 5232 HandleMark hm; | |
| 5233 | |
| 5234 // ---------- scan from roots -------------- | |
| 5235 _timer.start(); | |
| 5236 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 5237 Par_MarkRefsIntoClosure par_mri_cl(_collector->_span, &(_collector->_markBitMap)); | |
| 5238 | |
| 5239 // ---------- young gen roots -------------- | |
| 5240 { | |
| 5241 work_on_young_gen_roots(worker_id, &par_mri_cl); | |
| 5242 _timer.stop(); | |
| 5243 if (PrintCMSStatistics != 0) { | |
| 5244 gclog_or_tty->print_cr( | |
| 5245 "Finished young gen initial mark scan work in %dth thread: %3.3f sec", | |
| 5246 worker_id, _timer.seconds()); | |
| 5247 } | |
| 5248 } | |
| 5249 | |
| 5250 // ---------- remaining roots -------------- | |
| 5251 _timer.reset(); | |
| 5252 _timer.start(); | |
|
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|
5253 |
|
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|
5254 CLDToOopClosure cld_closure(&par_mri_cl, true); |
|
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|
5255 |
|
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|
5256 gch->gen_process_roots(_collector->_cmsGen->level(), |
|
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|
5257 false, // yg was scanned above |
|
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|
5258 false, // this is parallel code |
|
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|
5259 GenCollectedHeap::ScanningOption(_collector->CMSCollector::roots_scanning_options()), |
|
20278
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|
5260 _collector->should_unload_classes(), |
|
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|
5261 &par_mri_cl, |
|
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|
5262 NULL, |
|
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changeset
|
5263 &cld_closure); |
| 11975 | 5264 assert(_collector->should_unload_classes() |
|
23224
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diff
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|
5265 || (_collector->CMSCollector::roots_scanning_options() & GenCollectedHeap::SO_AllCodeCache), |
| 11975 | 5266 "if we didn't scan the code cache, we have to be ready to drop nmethods with expired weak oops"); |
| 5267 _timer.stop(); | |
| 5268 if (PrintCMSStatistics != 0) { | |
| 5269 gclog_or_tty->print_cr( | |
| 5270 "Finished remaining root initial mark scan work in %dth thread: %3.3f sec", | |
| 5271 worker_id, _timer.seconds()); | |
| 5272 } | |
| 5273 } | |
| 5274 | |
| 0 | 5275 // Parallel remark task |
| 11975 | 5276 class CMSParRemarkTask: public CMSParMarkTask { |
| 0 | 5277 CompactibleFreeListSpace* _cms_space; |
| 5278 | |
| 5279 // The per-thread work queues, available here for stealing. | |
| 5280 OopTaskQueueSet* _task_queues; | |
| 5281 ParallelTaskTerminator _term; | |
| 5282 | |
| 5283 public: | |
|
4095
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
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3979
diff
changeset
|
5284 // A value of 0 passed to n_workers will cause the number of |
|
bca17e38de00
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3979
diff
changeset
|
5285 // workers to be taken from the active workers in the work gang. |
| 0 | 5286 CMSParRemarkTask(CMSCollector* collector, |
| 5287 CompactibleFreeListSpace* cms_space, | |
|
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|
5288 int n_workers, FlexibleWorkGang* workers, |
| 0 | 5289 OopTaskQueueSet* task_queues): |
| 11975 | 5290 CMSParMarkTask("Rescan roots and grey objects in parallel", |
| 5291 collector, n_workers), | |
|
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|
5292 _cms_space(cms_space), |
| 0 | 5293 _task_queues(task_queues), |
|
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|
5294 _term(n_workers, task_queues) { } |
| 0 | 5295 |
| 5296 OopTaskQueueSet* task_queues() { return _task_queues; } | |
| 5297 | |
| 5298 OopTaskQueue* work_queue(int i) { return task_queues()->queue(i); } | |
| 5299 | |
| 5300 ParallelTaskTerminator* terminator() { return &_term; } | |
|
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|
5301 int n_workers() { return _n_workers; } |
| 0 | 5302 |
|
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|
5303 void work(uint worker_id); |
| 0 | 5304 |
| 5305 private: | |
| 5306 // ... of dirty cards in old space | |
| 5307 void do_dirty_card_rescan_tasks(CompactibleFreeListSpace* sp, int i, | |
| 5308 Par_MarkRefsIntoAndScanClosure* cl); | |
| 5309 | |
| 5310 // ... work stealing for the above | |
| 5311 void do_work_steal(int i, Par_MarkRefsIntoAndScanClosure* cl, int* seed); | |
| 5312 }; | |
| 5313 | |
|
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|
5314 class RemarkKlassClosure : public KlassClosure { |
|
20268
4c1b88a53c74
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stefank
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20264
diff
changeset
|
5315 KlassToOopClosure _cm_klass_closure; |
|
6725
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|
5316 public: |
|
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|
5317 RemarkKlassClosure(OopClosure* oop_closure) : _cm_klass_closure(oop_closure) {} |
|
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|
5318 void do_klass(Klass* k) { |
|
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|
5319 // Check if we have modified any oops in the Klass during the concurrent marking. |
|
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|
5320 if (k->has_accumulated_modified_oops()) { |
|
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|
5321 k->clear_accumulated_modified_oops(); |
|
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|
5322 |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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6197
diff
changeset
|
5323 // We could have transfered the current modified marks to the accumulated marks, |
|
da91efe96a93
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diff
changeset
|
5324 // like we do with the Card Table to Mod Union Table. But it's not really necessary. |
|
da91efe96a93
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diff
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|
5325 } else if (k->has_modified_oops()) { |
|
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6197
diff
changeset
|
5326 // Don't clear anything, this info is needed by the next young collection. |
|
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coleenp
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6197
diff
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|
5327 } else { |
|
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6197
diff
changeset
|
5328 // No modified oops in the Klass. |
|
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6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
5329 return; |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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6197
diff
changeset
|
5330 } |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
5331 |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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6197
diff
changeset
|
5332 // The klass has modified fields, need to scan the klass. |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
5333 _cm_klass_closure.do_klass(k); |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
5334 } |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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diff
changeset
|
5335 }; |
|
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|
5336 |
| 11975 | 5337 void CMSParMarkTask::work_on_young_gen_roots(uint worker_id, OopsInGenClosure* cl) { |
| 5338 DefNewGeneration* dng = _collector->_young_gen->as_DefNewGeneration(); | |
| 5339 EdenSpace* eden_space = dng->eden(); | |
| 5340 ContiguousSpace* from_space = dng->from(); | |
| 5341 ContiguousSpace* to_space = dng->to(); | |
| 5342 | |
| 5343 HeapWord** eca = _collector->_eden_chunk_array; | |
| 5344 size_t ect = _collector->_eden_chunk_index; | |
| 5345 HeapWord** sca = _collector->_survivor_chunk_array; | |
| 5346 size_t sct = _collector->_survivor_chunk_index; | |
| 5347 | |
| 5348 assert(ect <= _collector->_eden_chunk_capacity, "out of bounds"); | |
| 5349 assert(sct <= _collector->_survivor_chunk_capacity, "out of bounds"); | |
| 5350 | |
| 5351 do_young_space_rescan(worker_id, cl, to_space, NULL, 0); | |
| 5352 do_young_space_rescan(worker_id, cl, from_space, sca, sct); | |
| 5353 do_young_space_rescan(worker_id, cl, eden_space, eca, ect); | |
| 5354 } | |
| 5355 | |
|
1833
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6984287: Regularize how GC parallel workers are specified.
jmasa
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1777
diff
changeset
|
5356 // work_queue(i) is passed to the closure |
|
8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
jmasa
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1777
diff
changeset
|
5357 // Par_MarkRefsIntoAndScanClosure. The "i" parameter |
|
8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
jmasa
parents:
1777
diff
changeset
|
5358 // also is passed to do_dirty_card_rescan_tasks() and to |
|
8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
jmasa
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1777
diff
changeset
|
5359 // do_work_steal() to select the i-th task_queue. |
|
8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
jmasa
parents:
1777
diff
changeset
|
5360 |
|
4728
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7121618: Change type of number of GC workers to unsigned int.
jmasa
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4128
diff
changeset
|
5361 void CMSParRemarkTask::work(uint worker_id) { |
| 0 | 5362 elapsedTimer _timer; |
| 5363 ResourceMark rm; | |
| 5364 HandleMark hm; | |
| 5365 | |
| 5366 // ---------- rescan from roots -------------- | |
| 5367 _timer.start(); | |
| 5368 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 5369 Par_MarkRefsIntoAndScanClosure par_mrias_cl(_collector, | |
| 5370 _collector->_span, _collector->ref_processor(), | |
| 5371 &(_collector->_markBitMap), | |
|
6725
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diff
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|
5372 work_queue(worker_id)); |
| 0 | 5373 |
| 5374 // Rescan young gen roots first since these are likely | |
| 5375 // coarsely partitioned and may, on that account, constitute | |
| 5376 // the critical path; thus, it's best to start off that | |
| 5377 // work first. | |
| 5378 // ---------- young gen roots -------------- | |
| 5379 { | |
| 11975 | 5380 work_on_young_gen_roots(worker_id, &par_mrias_cl); |
| 0 | 5381 _timer.stop(); |
| 5382 if (PrintCMSStatistics != 0) { | |
| 5383 gclog_or_tty->print_cr( | |
| 5384 "Finished young gen rescan work in %dth thread: %3.3f sec", | |
|
4728
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jmasa
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4128
diff
changeset
|
5385 worker_id, _timer.seconds()); |
| 0 | 5386 } |
| 5387 } | |
| 5388 | |
| 5389 // ---------- remaining roots -------------- | |
| 5390 _timer.reset(); | |
| 5391 _timer.start(); | |
|
20278
2c6ef90f030a
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stefank
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20268
diff
changeset
|
5392 gch->gen_process_roots(_collector->_cmsGen->level(), |
|
2c6ef90f030a
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stefank
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20268
diff
changeset
|
5393 false, // yg was scanned above |
|
2c6ef90f030a
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stefank
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20268
diff
changeset
|
5394 false, // this is parallel code |
|
23224
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mgerdin
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20762
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changeset
|
5395 GenCollectedHeap::ScanningOption(_collector->CMSCollector::roots_scanning_options()), |
|
20278
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stefank
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changeset
|
5396 _collector->should_unload_classes(), |
|
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stefank
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diff
changeset
|
5397 &par_mrias_cl, |
|
2c6ef90f030a
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stefank
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20268
diff
changeset
|
5398 NULL, |
|
2c6ef90f030a
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stefank
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20268
diff
changeset
|
5399 NULL); // The dirty klasses will be handled below |
|
2c6ef90f030a
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stefank
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20268
diff
changeset
|
5400 |
|
989
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
5401 assert(_collector->should_unload_classes() |
|
23224
79b13c9a93e8
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mgerdin
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20762
diff
changeset
|
5402 || (_collector->CMSCollector::roots_scanning_options() & GenCollectedHeap::SO_AllCodeCache), |
|
989
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
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798
diff
changeset
|
5403 "if we didn't scan the code cache, we have to be ready to drop nmethods with expired weak oops"); |
| 0 | 5404 _timer.stop(); |
| 5405 if (PrintCMSStatistics != 0) { | |
| 5406 gclog_or_tty->print_cr( | |
| 5407 "Finished remaining root rescan work in %dth thread: %3.3f sec", | |
|
4728
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4128
diff
changeset
|
5408 worker_id, _timer.seconds()); |
| 0 | 5409 } |
| 5410 | |
|
6725
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6197
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changeset
|
5411 // ---------- unhandled CLD scanning ---------- |
|
da91efe96a93
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coleenp
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6197
diff
changeset
|
5412 if (worker_id == 0) { // Single threaded at the moment. |
|
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coleenp
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6197
diff
changeset
|
5413 _timer.reset(); |
|
da91efe96a93
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6197
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changeset
|
5414 _timer.start(); |
|
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changeset
|
5415 |
|
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6964458: Reimplement class meta-data storage to use native memory
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6197
diff
changeset
|
5416 // Scan all new class loader data objects and new dependencies that were |
|
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6197
diff
changeset
|
5417 // introduced during concurrent marking. |
|
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coleenp
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6197
diff
changeset
|
5418 ResourceMark rm; |
|
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changeset
|
5419 GrowableArray<ClassLoaderData*>* array = ClassLoaderDataGraph::new_clds(); |
|
da91efe96a93
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coleenp
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diff
changeset
|
5420 for (int i = 0; i < array->length(); i++) { |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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5421 par_mrias_cl.do_class_loader_data(array->at(i)); |
|
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5422 } |
|
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5423 |
|
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5424 // We don't need to keep track of new CLDs anymore. |
|
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5425 ClassLoaderDataGraph::remember_new_clds(false); |
|
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5426 |
|
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|
5427 _timer.stop(); |
|
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|
5428 if (PrintCMSStatistics != 0) { |
|
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5429 gclog_or_tty->print_cr( |
|
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5430 "Finished unhandled CLD scanning work in %dth thread: %3.3f sec", |
|
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5431 worker_id, _timer.seconds()); |
|
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5432 } |
|
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5433 } |
|
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5434 |
|
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5435 // ---------- dirty klass scanning ---------- |
|
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5436 if (worker_id == 0) { // Single threaded at the moment. |
|
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5437 _timer.reset(); |
|
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5438 _timer.start(); |
|
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5439 |
|
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|
5440 // Scan all classes that was dirtied during the concurrent marking phase. |
|
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5441 RemarkKlassClosure remark_klass_closure(&par_mrias_cl); |
|
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5442 ClassLoaderDataGraph::classes_do(&remark_klass_closure); |
|
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5443 |
|
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5444 _timer.stop(); |
|
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5445 if (PrintCMSStatistics != 0) { |
|
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5446 gclog_or_tty->print_cr( |
|
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5447 "Finished dirty klass scanning work in %dth thread: %3.3f sec", |
|
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5448 worker_id, _timer.seconds()); |
|
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5449 } |
|
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|
5450 } |
|
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5451 |
|
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5452 // We might have added oops to ClassLoaderData::_handles during the |
|
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5453 // concurrent marking phase. These oops point to newly allocated objects |
|
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5454 // that are guaranteed to be kept alive. Either by the direct allocation |
|
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|
5455 // code, or when the young collector processes the roots. Hence, |
|
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5456 // we don't have to revisit the _handles block during the remark phase. |
|
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|
5457 |
| 0 | 5458 // ---------- rescan dirty cards ------------ |
| 5459 _timer.reset(); | |
| 5460 _timer.start(); | |
| 5461 | |
| 5462 // Do the rescan tasks for each of the two spaces | |
|
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5463 // (cms_space) in turn. |
|
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|
5464 // "worker_id" is passed to select the task_queue for "worker_id" |
|
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|
5465 do_dirty_card_rescan_tasks(_cms_space, worker_id, &par_mrias_cl); |
| 0 | 5466 _timer.stop(); |
| 5467 if (PrintCMSStatistics != 0) { | |
| 5468 gclog_or_tty->print_cr( | |
| 5469 "Finished dirty card rescan work in %dth thread: %3.3f sec", | |
|
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|
5470 worker_id, _timer.seconds()); |
| 0 | 5471 } |
| 5472 | |
| 5473 // ---------- steal work from other threads ... | |
| 5474 // ---------- ... and drain overflow list. | |
| 5475 _timer.reset(); | |
| 5476 _timer.start(); | |
|
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|
5477 do_work_steal(worker_id, &par_mrias_cl, _collector->hash_seed(worker_id)); |
| 0 | 5478 _timer.stop(); |
| 5479 if (PrintCMSStatistics != 0) { | |
| 5480 gclog_or_tty->print_cr( | |
| 5481 "Finished work stealing in %dth thread: %3.3f sec", | |
|
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|
5482 worker_id, _timer.seconds()); |
| 0 | 5483 } |
| 5484 } | |
| 5485 | |
|
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|
5486 // Note that parameter "i" is not used. |
| 0 | 5487 void |
| 11975 | 5488 CMSParMarkTask::do_young_space_rescan(uint worker_id, |
| 5489 OopsInGenClosure* cl, ContiguousSpace* space, | |
| 0 | 5490 HeapWord** chunk_array, size_t chunk_top) { |
| 5491 // Until all tasks completed: | |
| 5492 // . claim an unclaimed task | |
| 5493 // . compute region boundaries corresponding to task claimed | |
| 5494 // using chunk_array | |
| 5495 // . par_oop_iterate(cl) over that region | |
| 5496 | |
| 5497 ResourceMark rm; | |
| 5498 HandleMark hm; | |
| 5499 | |
| 5500 SequentialSubTasksDone* pst = space->par_seq_tasks(); | |
| 5501 | |
|
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|
5502 uint nth_task = 0; |
|
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|
5503 uint n_tasks = pst->n_tasks(); |
| 0 | 5504 |
|
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|
5505 if (n_tasks > 0) { |
|
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|
5506 assert(pst->valid(), "Uninitialized use?"); |
|
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|
5507 HeapWord *start, *end; |
|
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|
5508 while (!pst->is_task_claimed(/* reference */ nth_task)) { |
|
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|
5509 // We claimed task # nth_task; compute its boundaries. |
|
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|
5510 if (chunk_top == 0) { // no samples were taken |
|
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|
5511 assert(nth_task == 0 && n_tasks == 1, "Can have only 1 EdenSpace task"); |
|
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|
5512 start = space->bottom(); |
|
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|
5513 end = space->top(); |
|
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|
5514 } else if (nth_task == 0) { |
|
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|
5515 start = space->bottom(); |
|
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|
5516 end = chunk_array[nth_task]; |
|
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|
5517 } else if (nth_task < (uint)chunk_top) { |
|
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|
5518 assert(nth_task >= 1, "Control point invariant"); |
|
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|
5519 start = chunk_array[nth_task - 1]; |
|
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|
5520 end = chunk_array[nth_task]; |
|
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|
5521 } else { |
|
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|
5522 assert(nth_task == (uint)chunk_top, "Control point invariant"); |
|
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|
5523 start = chunk_array[chunk_top - 1]; |
|
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|
5524 end = space->top(); |
|
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|
5525 } |
|
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|
5526 MemRegion mr(start, end); |
|
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|
5527 // Verify that mr is in space |
|
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|
5528 assert(mr.is_empty() || space->used_region().contains(mr), |
|
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|
5529 "Should be in space"); |
|
cb9da55b1990
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changeset
|
5530 // Verify that "start" is an object boundary |
|
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diff
changeset
|
5531 assert(mr.is_empty() || oop(mr.start())->is_oop(), |
|
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|
5532 "Should be an oop"); |
|
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|
5533 space->par_oop_iterate(mr, cl); |
|
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|
5534 } |
|
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|
5535 pst->all_tasks_completed(); |
|
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|
5536 } |
| 0 | 5537 } |
| 5538 | |
| 5539 void | |
| 5540 CMSParRemarkTask::do_dirty_card_rescan_tasks( | |
| 5541 CompactibleFreeListSpace* sp, int i, | |
| 5542 Par_MarkRefsIntoAndScanClosure* cl) { | |
| 5543 // Until all tasks completed: | |
| 5544 // . claim an unclaimed task | |
| 5545 // . compute region boundaries corresponding to task claimed | |
| 5546 // . transfer dirty bits ct->mut for that region | |
| 5547 // . apply rescanclosure to dirty mut bits for that region | |
| 5548 | |
| 5549 ResourceMark rm; | |
| 5550 HandleMark hm; | |
| 5551 | |
| 5552 OopTaskQueue* work_q = work_queue(i); | |
| 5553 ModUnionClosure modUnionClosure(&(_collector->_modUnionTable)); | |
| 5554 // CAUTION! CAUTION! CAUTION! CAUTION! CAUTION! CAUTION! CAUTION! | |
| 5555 // CAUTION: This closure has state that persists across calls to | |
| 5556 // the work method dirty_range_iterate_clear() in that it has | |
| 5557 // imbedded in it a (subtype of) UpwardsObjectClosure. The | |
| 5558 // use of that state in the imbedded UpwardsObjectClosure instance | |
| 5559 // assumes that the cards are always iterated (even if in parallel | |
| 5560 // by several threads) in monotonically increasing order per each | |
| 5561 // thread. This is true of the implementation below which picks | |
| 5562 // card ranges (chunks) in monotonically increasing order globally | |
| 5563 // and, a-fortiori, in monotonically increasing order per thread | |
| 5564 // (the latter order being a subsequence of the former). | |
| 5565 // If the work code below is ever reorganized into a more chaotic | |
| 5566 // work-partitioning form than the current "sequential tasks" | |
| 5567 // paradigm, the use of that persistent state will have to be | |
| 5568 // revisited and modified appropriately. See also related | |
| 5569 // bug 4756801 work on which should examine this code to make | |
| 5570 // sure that the changes there do not run counter to the | |
| 5571 // assumptions made here and necessary for correctness and | |
| 5572 // efficiency. Note also that this code might yield inefficient | |
| 5573 // behaviour in the case of very large objects that span one or | |
| 5574 // more work chunks. Such objects would potentially be scanned | |
| 5575 // several times redundantly. Work on 4756801 should try and | |
| 5576 // address that performance anomaly if at all possible. XXX | |
| 5577 MemRegion full_span = _collector->_span; | |
| 5578 CMSBitMap* bm = &(_collector->_markBitMap); // shared | |
| 5579 MarkFromDirtyCardsClosure | |
| 5580 greyRescanClosure(_collector, full_span, // entire span of interest | |
|
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5581 sp, bm, work_q, cl); |
| 0 | 5582 |
| 5583 SequentialSubTasksDone* pst = sp->conc_par_seq_tasks(); | |
| 5584 assert(pst->valid(), "Uninitialized use?"); | |
|
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|
5585 uint nth_task = 0; |
| 0 | 5586 const int alignment = CardTableModRefBS::card_size * BitsPerWord; |
| 5587 MemRegion span = sp->used_region(); | |
| 5588 HeapWord* start_addr = span.start(); | |
| 5589 HeapWord* end_addr = (HeapWord*)round_to((intptr_t)span.end(), | |
| 5590 alignment); | |
| 5591 const size_t chunk_size = sp->rescan_task_size(); // in HeapWord units | |
| 5592 assert((HeapWord*)round_to((intptr_t)start_addr, alignment) == | |
| 5593 start_addr, "Check alignment"); | |
| 5594 assert((size_t)round_to((intptr_t)chunk_size, alignment) == | |
| 5595 chunk_size, "Check alignment"); | |
| 5596 | |
| 5597 while (!pst->is_task_claimed(/* reference */ nth_task)) { | |
| 5598 // Having claimed the nth_task, compute corresponding mem-region, | |
| 5599 // which is a-fortiori aligned correctly (i.e. at a MUT bopundary). | |
| 5600 // The alignment restriction ensures that we do not need any | |
| 5601 // synchronization with other gang-workers while setting or | |
| 5602 // clearing bits in thus chunk of the MUT. | |
| 5603 MemRegion this_span = MemRegion(start_addr + nth_task*chunk_size, | |
| 5604 start_addr + (nth_task+1)*chunk_size); | |
| 5605 // The last chunk's end might be way beyond end of the | |
| 5606 // used region. In that case pull back appropriately. | |
| 5607 if (this_span.end() > end_addr) { | |
| 5608 this_span.set_end(end_addr); | |
| 5609 assert(!this_span.is_empty(), "Program logic (calculation of n_tasks)"); | |
| 5610 } | |
| 5611 // Iterate over the dirty cards covering this chunk, marking them | |
| 5612 // precleaned, and setting the corresponding bits in the mod union | |
| 5613 // table. Since we have been careful to partition at Card and MUT-word | |
| 5614 // boundaries no synchronization is needed between parallel threads. | |
| 5615 _collector->_ct->ct_bs()->dirty_card_iterate(this_span, | |
| 5616 &modUnionClosure); | |
| 5617 | |
| 5618 // Having transferred these marks into the modUnionTable, | |
| 5619 // rescan the marked objects on the dirty cards in the modUnionTable. | |
| 5620 // Even if this is at a synchronous collection, the initial marking | |
| 5621 // may have been done during an asynchronous collection so there | |
| 5622 // may be dirty bits in the mod-union table. | |
| 5623 _collector->_modUnionTable.dirty_range_iterate_clear( | |
| 5624 this_span, &greyRescanClosure); | |
| 5625 _collector->_modUnionTable.verifyNoOneBitsInRange( | |
| 5626 this_span.start(), | |
| 5627 this_span.end()); | |
| 5628 } | |
| 5629 pst->all_tasks_completed(); // declare that i am done | |
| 5630 } | |
| 5631 | |
| 5632 // . see if we can share work_queues with ParNew? XXX | |
| 5633 void | |
| 5634 CMSParRemarkTask::do_work_steal(int i, Par_MarkRefsIntoAndScanClosure* cl, | |
| 5635 int* seed) { | |
| 5636 OopTaskQueue* work_q = work_queue(i); | |
| 5637 NOT_PRODUCT(int num_steals = 0;) | |
| 5638 oop obj_to_scan; | |
| 5639 CMSBitMap* bm = &(_collector->_markBitMap); | |
| 5640 | |
| 5641 while (true) { | |
| 5642 // Completely finish any left over work from (an) earlier round(s) | |
| 5643 cl->trim_queue(0); | |
|
679
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628
diff
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|
5644 size_t num_from_overflow_list = MIN2((size_t)(work_q->max_elems() - work_q->size())/4, |
|
cea947c8a988
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628
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|
5645 (size_t)ParGCDesiredObjsFromOverflowList); |
| 0 | 5646 // Now check if there's any work in the overflow list |
|
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5647 // Passing ParallelGCThreads as the third parameter, no_of_gc_threads, |
|
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5648 // only affects the number of attempts made to get work from the |
|
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5649 // overflow list and does not affect the number of workers. Just |
|
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5650 // pass ParallelGCThreads so this behavior is unchanged. |
| 0 | 5651 if (_collector->par_take_from_overflow_list(num_from_overflow_list, |
|
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5652 work_q, |
|
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5653 ParallelGCThreads)) { |
| 0 | 5654 // found something in global overflow list; |
| 5655 // not yet ready to go stealing work from others. | |
| 5656 // We'd like to assert(work_q->size() != 0, ...) | |
| 5657 // because we just took work from the overflow list, | |
| 5658 // but of course we can't since all of that could have | |
| 5659 // been already stolen from us. | |
| 5660 // "He giveth and He taketh away." | |
| 5661 continue; | |
| 5662 } | |
| 5663 // Verify that we have no work before we resort to stealing | |
| 5664 assert(work_q->size() == 0, "Have work, shouldn't steal"); | |
| 5665 // Try to steal from other queues that have work | |
| 5666 if (task_queues()->steal(i, seed, /* reference */ obj_to_scan)) { | |
| 5667 NOT_PRODUCT(num_steals++;) | |
| 5668 assert(obj_to_scan->is_oop(), "Oops, not an oop!"); | |
| 5669 assert(bm->isMarked((HeapWord*)obj_to_scan), "Stole an unmarked oop?"); | |
| 5670 // Do scanning work | |
| 5671 obj_to_scan->oop_iterate(cl); | |
| 5672 // Loop around, finish this work, and try to steal some more | |
| 5673 } else if (terminator()->offer_termination()) { | |
| 5674 break; // nirvana from the infinite cycle | |
| 5675 } | |
| 5676 } | |
| 5677 NOT_PRODUCT( | |
| 5678 if (PrintCMSStatistics != 0) { | |
| 5679 gclog_or_tty->print("\n\t(%d: stole %d oops)", i, num_steals); | |
| 5680 } | |
| 5681 ) | |
| 5682 assert(work_q->size() == 0 && _collector->overflow_list_is_empty(), | |
| 5683 "Else our work is not yet done"); | |
| 5684 } | |
| 5685 | |
|
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5686 // Record object boundaries in _eden_chunk_array by sampling the eden |
|
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5687 // top in the slow-path eden object allocation code path and record |
|
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5688 // the boundaries, if CMSEdenChunksRecordAlways is true. If |
|
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5689 // CMSEdenChunksRecordAlways is false, we use the other asynchronous |
|
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5690 // sampling in sample_eden() that activates during the part of the |
|
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5691 // preclean phase. |
|
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5692 void CMSCollector::sample_eden_chunk() { |
|
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5693 if (CMSEdenChunksRecordAlways && _eden_chunk_array != NULL) { |
|
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5694 if (_eden_chunk_lock->try_lock()) { |
|
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5695 // Record a sample. This is the critical section. The contents |
|
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5696 // of the _eden_chunk_array have to be non-decreasing in the |
|
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5697 // address order. |
|
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5698 _eden_chunk_array[_eden_chunk_index] = *_top_addr; |
|
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5699 assert(_eden_chunk_array[_eden_chunk_index] <= *_end_addr, |
|
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5700 "Unexpected state of Eden"); |
|
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5701 if (_eden_chunk_index == 0 || |
|
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5702 ((_eden_chunk_array[_eden_chunk_index] > _eden_chunk_array[_eden_chunk_index-1]) && |
|
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5703 (pointer_delta(_eden_chunk_array[_eden_chunk_index], |
|
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5704 _eden_chunk_array[_eden_chunk_index-1]) >= CMSSamplingGrain))) { |
|
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|
5705 _eden_chunk_index++; // commit sample |
|
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5706 } |
|
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5707 _eden_chunk_lock->unlock(); |
|
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5708 } |
|
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5709 } |
|
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5710 } |
|
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|
5711 |
| 0 | 5712 // Return a thread-local PLAB recording array, as appropriate. |
| 5713 void* CMSCollector::get_data_recorder(int thr_num) { | |
| 5714 if (_survivor_plab_array != NULL && | |
| 5715 (CMSPLABRecordAlways || | |
| 5716 (_collectorState > Marking && _collectorState < FinalMarking))) { | |
| 5717 assert(thr_num < (int)ParallelGCThreads, "thr_num is out of bounds"); | |
| 5718 ChunkArray* ca = &_survivor_plab_array[thr_num]; | |
| 5719 ca->reset(); // clear it so that fresh data is recorded | |
| 5720 return (void*) ca; | |
| 5721 } else { | |
| 5722 return NULL; | |
| 5723 } | |
| 5724 } | |
| 5725 | |
| 5726 // Reset all the thread-local PLAB recording arrays | |
| 5727 void CMSCollector::reset_survivor_plab_arrays() { | |
| 5728 for (uint i = 0; i < ParallelGCThreads; i++) { | |
| 5729 _survivor_plab_array[i].reset(); | |
| 5730 } | |
| 5731 } | |
| 5732 | |
| 5733 // Merge the per-thread plab arrays into the global survivor chunk | |
| 5734 // array which will provide the partitioning of the survivor space | |
| 11975 | 5735 // for CMS initial scan and rescan. |
|
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|
5736 void CMSCollector::merge_survivor_plab_arrays(ContiguousSpace* surv, |
|
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|
5737 int no_of_gc_threads) { |
| 0 | 5738 assert(_survivor_plab_array != NULL, "Error"); |
| 5739 assert(_survivor_chunk_array != NULL, "Error"); | |
| 11975 | 5740 assert(_collectorState == FinalMarking || |
| 5741 (CMSParallelInitialMarkEnabled && _collectorState == InitialMarking), "Error"); | |
|
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|
5742 for (int j = 0; j < no_of_gc_threads; j++) { |
| 0 | 5743 _cursor[j] = 0; |
| 5744 } | |
| 5745 HeapWord* top = surv->top(); | |
| 5746 size_t i; | |
| 5747 for (i = 0; i < _survivor_chunk_capacity; i++) { // all sca entries | |
| 5748 HeapWord* min_val = top; // Higher than any PLAB address | |
| 5749 uint min_tid = 0; // position of min_val this round | |
|
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|
5750 for (int j = 0; j < no_of_gc_threads; j++) { |
| 0 | 5751 ChunkArray* cur_sca = &_survivor_plab_array[j]; |
| 5752 if (_cursor[j] == cur_sca->end()) { | |
| 5753 continue; | |
| 5754 } | |
| 5755 assert(_cursor[j] < cur_sca->end(), "ctl pt invariant"); | |
| 5756 HeapWord* cur_val = cur_sca->nth(_cursor[j]); | |
| 5757 assert(surv->used_region().contains(cur_val), "Out of bounds value"); | |
| 5758 if (cur_val < min_val) { | |
| 5759 min_tid = j; | |
| 5760 min_val = cur_val; | |
| 5761 } else { | |
| 5762 assert(cur_val < top, "All recorded addresses should be less"); | |
| 5763 } | |
| 5764 } | |
| 5765 // At this point min_val and min_tid are respectively | |
| 5766 // the least address in _survivor_plab_array[j]->nth(_cursor[j]) | |
| 5767 // and the thread (j) that witnesses that address. | |
| 5768 // We record this address in the _survivor_chunk_array[i] | |
| 5769 // and increment _cursor[min_tid] prior to the next round i. | |
| 5770 if (min_val == top) { | |
| 5771 break; | |
| 5772 } | |
| 5773 _survivor_chunk_array[i] = min_val; | |
| 5774 _cursor[min_tid]++; | |
| 5775 } | |
| 5776 // We are all done; record the size of the _survivor_chunk_array | |
| 5777 _survivor_chunk_index = i; // exclusive: [0, i) | |
| 5778 if (PrintCMSStatistics > 0) { | |
| 5779 gclog_or_tty->print(" (Survivor:" SIZE_FORMAT "chunks) ", i); | |
| 5780 } | |
| 5781 // Verify that we used up all the recorded entries | |
| 5782 #ifdef ASSERT | |
| 5783 size_t total = 0; | |
|
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|
5784 for (int j = 0; j < no_of_gc_threads; j++) { |
| 0 | 5785 assert(_cursor[j] == _survivor_plab_array[j].end(), "Ctl pt invariant"); |
| 5786 total += _cursor[j]; | |
| 5787 } | |
| 5788 assert(total == _survivor_chunk_index, "Ctl Pt Invariant"); | |
| 5789 // Check that the merged array is in sorted order | |
| 5790 if (total > 0) { | |
| 5791 for (size_t i = 0; i < total - 1; i++) { | |
| 5792 if (PrintCMSStatistics > 0) { | |
| 5793 gclog_or_tty->print(" (chunk" SIZE_FORMAT ":" INTPTR_FORMAT ") ", | |
| 5794 i, _survivor_chunk_array[i]); | |
| 5795 } | |
| 5796 assert(_survivor_chunk_array[i] < _survivor_chunk_array[i+1], | |
| 5797 "Not sorted"); | |
| 5798 } | |
| 5799 } | |
| 5800 #endif // ASSERT | |
| 5801 } | |
| 5802 | |
| 5803 // Set up the space's par_seq_tasks structure for work claiming | |
| 11975 | 5804 // for parallel initial scan and rescan of young gen. |
| 0 | 5805 // See ParRescanTask where this is currently used. |
| 5806 void | |
| 5807 CMSCollector:: | |
| 5808 initialize_sequential_subtasks_for_young_gen_rescan(int n_threads) { | |
| 5809 assert(n_threads > 0, "Unexpected n_threads argument"); | |
| 5810 DefNewGeneration* dng = (DefNewGeneration*)_young_gen; | |
| 5811 | |
| 5812 // Eden space | |
|
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|
5813 if (!dng->eden()->is_empty()) { |
| 0 | 5814 SequentialSubTasksDone* pst = dng->eden()->par_seq_tasks(); |
| 5815 assert(!pst->valid(), "Clobbering existing data?"); | |
| 5816 // Each valid entry in [0, _eden_chunk_index) represents a task. | |
| 5817 size_t n_tasks = _eden_chunk_index + 1; | |
| 5818 assert(n_tasks == 1 || _eden_chunk_array != NULL, "Error"); | |
|
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|
5819 // Sets the condition for completion of the subtask (how many threads |
|
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|
5820 // need to finish in order to be done). |
|
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|
5821 pst->set_n_threads(n_threads); |
| 0 | 5822 pst->set_n_tasks((int)n_tasks); |
| 5823 } | |
| 5824 | |
| 5825 // Merge the survivor plab arrays into _survivor_chunk_array | |
| 5826 if (_survivor_plab_array != NULL) { | |
|
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|
5827 merge_survivor_plab_arrays(dng->from(), n_threads); |
| 0 | 5828 } else { |
| 5829 assert(_survivor_chunk_index == 0, "Error"); | |
| 5830 } | |
| 5831 | |
| 5832 // To space | |
| 5833 { | |
| 5834 SequentialSubTasksDone* pst = dng->to()->par_seq_tasks(); | |
| 5835 assert(!pst->valid(), "Clobbering existing data?"); | |
|
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|
5836 // Sets the condition for completion of the subtask (how many threads |
|
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|
5837 // need to finish in order to be done). |
|
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|
5838 pst->set_n_threads(n_threads); |
| 0 | 5839 pst->set_n_tasks(1); |
| 5840 assert(pst->valid(), "Error"); | |
| 5841 } | |
| 5842 | |
| 5843 // From space | |
| 5844 { | |
| 5845 SequentialSubTasksDone* pst = dng->from()->par_seq_tasks(); | |
| 5846 assert(!pst->valid(), "Clobbering existing data?"); | |
| 5847 size_t n_tasks = _survivor_chunk_index + 1; | |
| 5848 assert(n_tasks == 1 || _survivor_chunk_array != NULL, "Error"); | |
|
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|
5849 // Sets the condition for completion of the subtask (how many threads |
|
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|
5850 // need to finish in order to be done). |
|
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|
5851 pst->set_n_threads(n_threads); |
| 0 | 5852 pst->set_n_tasks((int)n_tasks); |
| 5853 assert(pst->valid(), "Error"); | |
| 5854 } | |
| 5855 } | |
| 5856 | |
| 5857 // Parallel version of remark | |
| 5858 void CMSCollector::do_remark_parallel() { | |
| 5859 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
|
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|
5860 FlexibleWorkGang* workers = gch->workers(); |
| 0 | 5861 assert(workers != NULL, "Need parallel worker threads."); |
|
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5862 // Choose to use the number of GC workers most recently set |
|
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5863 // into "active_workers". If active_workers is not set, set it |
|
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|
5864 // to ParallelGCThreads. |
|
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5865 int n_workers = workers->active_workers(); |
|
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|
5866 if (n_workers == 0) { |
|
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|
5867 assert(n_workers > 0, "Should have been set during scavenge"); |
|
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|
5868 n_workers = ParallelGCThreads; |
|
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|
5869 workers->set_active_workers(n_workers); |
|
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|
5870 } |
| 0 | 5871 CompactibleFreeListSpace* cms_space = _cmsGen->cmsSpace(); |
| 5872 | |
| 5873 CMSParRemarkTask tsk(this, | |
|
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|
5874 cms_space, |
| 0 | 5875 n_workers, workers, task_queues()); |
| 5876 | |
|
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|
5877 // Set up for parallel process_roots work. |
| 0 | 5878 gch->set_par_threads(n_workers); |
| 5879 // We won't be iterating over the cards in the card table updating | |
| 5880 // the younger_gen cards, so we shouldn't call the following else | |
| 5881 // the verification code as well as subsequent younger_refs_iterate | |
| 5882 // code would get confused. XXX | |
| 5883 // gch->rem_set()->prepare_for_younger_refs_iterate(true); // parallel | |
| 5884 | |
| 5885 // The young gen rescan work will not be done as part of | |
|
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|
5886 // process_roots (which currently doesn't know how to |
| 0 | 5887 // parallelize such a scan), but rather will be broken up into |
| 5888 // a set of parallel tasks (via the sampling that the [abortable] | |
| 5889 // preclean phase did of EdenSpace, plus the [two] tasks of | |
| 5890 // scanning the [two] survivor spaces. Further fine-grain | |
| 5891 // parallelization of the scanning of the survivor spaces | |
| 5892 // themselves, and of precleaning of the younger gen itself | |
| 5893 // is deferred to the future. | |
| 5894 initialize_sequential_subtasks_for_young_gen_rescan(n_workers); | |
| 5895 | |
| 5896 // The dirty card rescan work is broken up into a "sequence" | |
| 5897 // of parallel tasks (per constituent space) that are dynamically | |
| 5898 // claimed by the parallel threads. | |
| 5899 cms_space->initialize_sequential_subtasks_for_rescan(n_workers); | |
| 5900 | |
| 5901 // It turns out that even when we're using 1 thread, doing the work in a | |
| 5902 // separate thread causes wide variance in run times. We can't help this | |
| 5903 // in the multi-threaded case, but we special-case n=1 here to get | |
| 5904 // repeatable measurements of the 1-thread overhead of the parallel code. | |
| 5905 if (n_workers > 1) { | |
|
2369
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|
5906 // Make refs discovery MT-safe, if it isn't already: it may not |
|
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changeset
|
5907 // necessarily be so, since it's possible that we are doing |
|
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|
5908 // ST marking. |
|
92da084fefc9
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|
5909 ReferenceProcessorMTDiscoveryMutator mt(ref_processor(), true); |
|
989
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changeset
|
5910 GenCollectedHeap::StrongRootsScope srs(gch); |
| 0 | 5911 workers->run_task(&tsk); |
| 5912 } else { | |
|
4876
be649fefcdc2
7134655: Crash in reference processing when doing single-threaded remarking
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diff
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|
5913 ReferenceProcessorMTDiscoveryMutator mt(ref_processor(), false); |
|
989
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changeset
|
5914 GenCollectedHeap::StrongRootsScope srs(gch); |
| 0 | 5915 tsk.work(0); |
| 5916 } | |
|
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|
5917 |
| 0 | 5918 gch->set_par_threads(0); // 0 ==> non-parallel. |
| 5919 // restore, single-threaded for now, any preserved marks | |
| 5920 // as a result of work_q overflow | |
| 5921 restore_preserved_marks_if_any(); | |
| 5922 } | |
| 5923 | |
| 5924 // Non-parallel version of remark | |
| 5925 void CMSCollector::do_remark_non_parallel() { | |
| 5926 ResourceMark rm; | |
| 5927 HandleMark hm; | |
| 5928 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
|
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|
5929 ReferenceProcessorMTDiscoveryMutator mt(ref_processor(), false); |
|
be649fefcdc2
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|
5930 |
| 0 | 5931 MarkRefsIntoAndScanClosure |
|
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|
5932 mrias_cl(_span, ref_processor(), &_markBitMap, NULL /* not precleaning */, |
|
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changeset
|
5933 &_markStack, this, |
| 0 | 5934 false /* should_yield */, false /* not precleaning */); |
| 5935 MarkFromDirtyCardsClosure | |
| 5936 markFromDirtyCardsClosure(this, _span, | |
| 5937 NULL, // space is set further below | |
|
6725
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|
5938 &_markBitMap, &_markStack, &mrias_cl); |
| 0 | 5939 { |
|
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|
5940 GCTraceTime t("grey object rescan", PrintGCDetails, false, _gc_timer_cm, _gc_tracer_cm->gc_id()); |
|
342
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changeset
|
5941 // Iterate over the dirty cards, setting the corresponding bits in the |
|
37f87013dfd8
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|
5942 // mod union table. |
| 0 | 5943 { |
| 5944 ModUnionClosure modUnionClosure(&_modUnionTable); | |
| 5945 _ct->ct_bs()->dirty_card_iterate( | |
| 5946 _cmsGen->used_region(), | |
| 5947 &modUnionClosure); | |
| 5948 } | |
| 5949 // Having transferred these marks into the modUnionTable, we just need | |
| 5950 // to rescan the marked objects on the dirty cards in the modUnionTable. | |
| 5951 // The initial marking may have been done during an asynchronous | |
| 5952 // collection so there may be dirty bits in the mod-union table. | |
| 5953 const int alignment = | |
| 5954 CardTableModRefBS::card_size * BitsPerWord; | |
| 5955 { | |
| 5956 // ... First handle dirty cards in CMS gen | |
| 5957 markFromDirtyCardsClosure.set_space(_cmsGen->cmsSpace()); | |
| 5958 MemRegion ur = _cmsGen->used_region(); | |
| 5959 HeapWord* lb = ur.start(); | |
| 5960 HeapWord* ub = (HeapWord*)round_to((intptr_t)ur.end(), alignment); | |
| 5961 MemRegion cms_span(lb, ub); | |
| 5962 _modUnionTable.dirty_range_iterate_clear(cms_span, | |
| 5963 &markFromDirtyCardsClosure); | |
| 5964 verify_work_stacks_empty(); | |
| 5965 if (PrintCMSStatistics != 0) { | |
| 5966 gclog_or_tty->print(" (re-scanned "SIZE_FORMAT" dirty cards in cms gen) ", | |
| 5967 markFromDirtyCardsClosure.num_dirty_cards()); | |
| 5968 } | |
| 5969 } | |
| 5970 } | |
| 5971 if (VerifyDuringGC && | |
| 5972 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
| 5973 HandleMark hm; // Discard invalid handles created during verification | |
|
6865
4202510ee0fe
8000831: Heap verification output incorrect/incomplete
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6787
diff
changeset
|
5974 Universe::verify(); |
| 0 | 5975 } |
| 5976 { | |
|
20190
0982ec23da03
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brutisso
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diff
changeset
|
5977 GCTraceTime t("root rescan", PrintGCDetails, false, _gc_timer_cm, _gc_tracer_cm->gc_id()); |
| 0 | 5978 |
| 5979 verify_work_stacks_empty(); | |
| 5980 | |
| 5981 gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel. | |
|
989
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|
5982 GenCollectedHeap::StrongRootsScope srs(gch); |
|
20278
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|
5983 |
|
2c6ef90f030a
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changeset
|
5984 gch->gen_process_roots(_cmsGen->level(), |
|
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changeset
|
5985 true, // younger gens as roots |
|
2c6ef90f030a
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stefank
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changeset
|
5986 false, // use the local StrongRootsScope |
|
23224
79b13c9a93e8
8075210: Refactor strong root processing in order to allow G1 to evolve separately from GenCollectedHeap
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20762
diff
changeset
|
5987 GenCollectedHeap::ScanningOption(roots_scanning_options()), |
|
20278
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|
5988 should_unload_classes(), |
|
2c6ef90f030a
8049421: G1 Class Unloading after completing a concurrent mark cycle
stefank
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20268
diff
changeset
|
5989 &mrias_cl, |
|
2c6ef90f030a
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stefank
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20268
diff
changeset
|
5990 NULL, |
|
2c6ef90f030a
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diff
changeset
|
5991 NULL); // The dirty klasses will be handled below |
|
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|
5992 |
|
989
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diff
changeset
|
5993 assert(should_unload_classes() |
|
23224
79b13c9a93e8
8075210: Refactor strong root processing in order to allow G1 to evolve separately from GenCollectedHeap
mgerdin
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20762
diff
changeset
|
5994 || (roots_scanning_options() & GenCollectedHeap::SO_AllCodeCache), |
|
989
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6863023: need non-perm oops in code cache for JSR 292
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diff
changeset
|
5995 "if we didn't scan the code cache, we have to be ready to drop nmethods with expired weak oops"); |
| 0 | 5996 } |
|
6725
da91efe96a93
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changeset
|
5997 |
|
da91efe96a93
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|
5998 { |
|
20190
0982ec23da03
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diff
changeset
|
5999 GCTraceTime t("visit unhandled CLDs", PrintGCDetails, false, _gc_timer_cm, _gc_tracer_cm->gc_id()); |
|
6725
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|
6000 |
|
da91efe96a93
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changeset
|
6001 verify_work_stacks_empty(); |
|
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diff
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|
6002 |
|
da91efe96a93
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changeset
|
6003 // Scan all class loader data objects that might have been introduced |
|
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diff
changeset
|
6004 // during concurrent marking. |
|
da91efe96a93
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diff
changeset
|
6005 ResourceMark rm; |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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diff
changeset
|
6006 GrowableArray<ClassLoaderData*>* array = ClassLoaderDataGraph::new_clds(); |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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diff
changeset
|
6007 for (int i = 0; i < array->length(); i++) { |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
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diff
changeset
|
6008 mrias_cl.do_class_loader_data(array->at(i)); |
|
da91efe96a93
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diff
changeset
|
6009 } |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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diff
changeset
|
6010 |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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diff
changeset
|
6011 // We don't need to keep track of new CLDs anymore. |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
6012 ClassLoaderDataGraph::remember_new_clds(false); |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
6013 |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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6197
diff
changeset
|
6014 verify_work_stacks_empty(); |
|
da91efe96a93
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coleenp
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6197
diff
changeset
|
6015 } |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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6197
diff
changeset
|
6016 |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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6197
diff
changeset
|
6017 { |
|
20190
0982ec23da03
8043607: Add a GC id as a log decoration similar to PrintGCTimeStamps
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17976
diff
changeset
|
6018 GCTraceTime t("dirty klass scan", PrintGCDetails, false, _gc_timer_cm, _gc_tracer_cm->gc_id()); |
|
6725
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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6197
diff
changeset
|
6019 |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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6197
diff
changeset
|
6020 verify_work_stacks_empty(); |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
6021 |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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6197
diff
changeset
|
6022 RemarkKlassClosure remark_klass_closure(&mrias_cl); |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
6023 ClassLoaderDataGraph::classes_do(&remark_klass_closure); |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
6024 |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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6197
diff
changeset
|
6025 verify_work_stacks_empty(); |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
6026 } |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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6197
diff
changeset
|
6027 |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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6197
diff
changeset
|
6028 // We might have added oops to ClassLoaderData::_handles during the |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
6029 // concurrent marking phase. These oops point to newly allocated objects |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
6030 // that are guaranteed to be kept alive. Either by the direct allocation |
|
20278
2c6ef90f030a
8049421: G1 Class Unloading after completing a concurrent mark cycle
stefank
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20268
diff
changeset
|
6031 // code, or when the young collector processes the roots. Hence, |
|
6725
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
6032 // we don't have to revisit the _handles block during the remark phase. |
|
da91efe96a93
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coleenp
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6197
diff
changeset
|
6033 |
| 0 | 6034 verify_work_stacks_empty(); |
| 6035 // Restore evacuated mark words, if any, used for overflow list links | |
| 6036 if (!CMSOverflowEarlyRestoration) { | |
| 6037 restore_preserved_marks_if_any(); | |
| 6038 } | |
| 6039 verify_overflow_empty(); | |
| 6040 } | |
| 6041 | |
| 6042 //////////////////////////////////////////////////////// | |
| 6043 // Parallel Reference Processing Task Proxy Class | |
| 6044 //////////////////////////////////////////////////////// | |
|
1833
8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
jmasa
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1777
diff
changeset
|
6045 class CMSRefProcTaskProxy: public AbstractGangTaskWOopQueues { |
| 0 | 6046 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; |
| 6047 CMSCollector* _collector; | |
| 6048 CMSBitMap* _mark_bit_map; | |
|
143
b5489bb705c9
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diff
changeset
|
6049 const MemRegion _span; |
| 0 | 6050 ProcessTask& _task; |
| 6051 | |
| 6052 public: | |
| 6053 CMSRefProcTaskProxy(ProcessTask& task, | |
| 6054 CMSCollector* collector, | |
| 6055 const MemRegion& span, | |
| 6056 CMSBitMap* mark_bit_map, | |
|
1833
8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
jmasa
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1777
diff
changeset
|
6057 AbstractWorkGang* workers, |
| 0 | 6058 OopTaskQueueSet* task_queues): |
|
2369
92da084fefc9
6668573: CMS: reference processing crash if ParallelCMSThreads > ParallelGCThreads
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2365
diff
changeset
|
6059 // XXX Should superclass AGTWOQ also know about AWG since it knows |
|
92da084fefc9
6668573: CMS: reference processing crash if ParallelCMSThreads > ParallelGCThreads
ysr
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2365
diff
changeset
|
6060 // about the task_queues used by the AWG? Then it could initialize |
|
92da084fefc9
6668573: CMS: reference processing crash if ParallelCMSThreads > ParallelGCThreads
ysr
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2365
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changeset
|
6061 // the terminator() object. See 6984287. The set_for_termination() |
|
92da084fefc9
6668573: CMS: reference processing crash if ParallelCMSThreads > ParallelGCThreads
ysr
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2365
diff
changeset
|
6062 // below is a temporary band-aid for the regression in 6984287. |
|
1833
8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
jmasa
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1777
diff
changeset
|
6063 AbstractGangTaskWOopQueues("Process referents by policy in parallel", |
|
8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
jmasa
parents:
1777
diff
changeset
|
6064 task_queues), |
| 0 | 6065 _task(task), |
|
1833
8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
jmasa
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1777
diff
changeset
|
6066 _collector(collector), _span(span), _mark_bit_map(mark_bit_map) |
|
2369
92da084fefc9
6668573: CMS: reference processing crash if ParallelCMSThreads > ParallelGCThreads
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2365
diff
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|
6067 { |
|
92da084fefc9
6668573: CMS: reference processing crash if ParallelCMSThreads > ParallelGCThreads
ysr
parents:
2365
diff
changeset
|
6068 assert(_collector->_span.equals(_span) && !_span.is_empty(), |
|
92da084fefc9
6668573: CMS: reference processing crash if ParallelCMSThreads > ParallelGCThreads
ysr
parents:
2365
diff
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|
6069 "Inconsistency in _span"); |
|
92da084fefc9
6668573: CMS: reference processing crash if ParallelCMSThreads > ParallelGCThreads
ysr
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2365
diff
changeset
|
6070 set_for_termination(workers->active_workers()); |
|
92da084fefc9
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ysr
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2365
diff
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|
6071 } |
| 0 | 6072 |
|
1833
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jmasa
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1777
diff
changeset
|
6073 OopTaskQueueSet* task_queues() { return queues(); } |
| 0 | 6074 |
| 6075 OopTaskQueue* work_queue(int i) { return task_queues()->queue(i); } | |
| 6076 | |
| 6077 void do_work_steal(int i, | |
| 6078 CMSParDrainMarkingStackClosure* drain, | |
| 6079 CMSParKeepAliveClosure* keep_alive, | |
| 6080 int* seed); | |
| 6081 | |
|
4728
441e946dc1af
7121618: Change type of number of GC workers to unsigned int.
jmasa
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4128
diff
changeset
|
6082 virtual void work(uint worker_id); |
| 0 | 6083 }; |
| 6084 | |
|
4728
441e946dc1af
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jmasa
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4128
diff
changeset
|
6085 void CMSRefProcTaskProxy::work(uint worker_id) { |
|
20297
ca8b8e21e2ca
8050973: CMS/G1 GC: add missing Resource and Handle mark
mdoerr
parents:
20278
diff
changeset
|
6086 ResourceMark rm; |
|
ca8b8e21e2ca
8050973: CMS/G1 GC: add missing Resource and Handle mark
mdoerr
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20278
diff
changeset
|
6087 HandleMark hm; |
|
143
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|
6088 assert(_collector->_span.equals(_span), "Inconsistency in _span"); |
| 0 | 6089 CMSParKeepAliveClosure par_keep_alive(_collector, _span, |
| 935 | 6090 _mark_bit_map, |
|
4728
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jmasa
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4128
diff
changeset
|
6091 work_queue(worker_id)); |
| 0 | 6092 CMSParDrainMarkingStackClosure par_drain_stack(_collector, _span, |
| 935 | 6093 _mark_bit_map, |
|
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4128
diff
changeset
|
6094 work_queue(worker_id)); |
|
143
b5489bb705c9
6662086: 6u4+, 7b11+: CMS never clears referents when -XX:+ParallelRefProcEnabled
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113
diff
changeset
|
6095 CMSIsAliveClosure is_alive_closure(_span, _mark_bit_map); |
|
4728
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jmasa
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diff
changeset
|
6096 _task.work(worker_id, is_alive_closure, par_keep_alive, par_drain_stack); |
| 0 | 6097 if (_task.marks_oops_alive()) { |
|
4728
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jmasa
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diff
changeset
|
6098 do_work_steal(worker_id, &par_drain_stack, &par_keep_alive, |
|
441e946dc1af
7121618: Change type of number of GC workers to unsigned int.
jmasa
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4128
diff
changeset
|
6099 _collector->hash_seed(worker_id)); |
|
441e946dc1af
7121618: Change type of number of GC workers to unsigned int.
jmasa
parents:
4128
diff
changeset
|
6100 } |
|
441e946dc1af
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jmasa
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4128
diff
changeset
|
6101 assert(work_queue(worker_id)->size() == 0, "work_queue should be empty"); |
| 0 | 6102 assert(_collector->_overflow_list == NULL, "non-empty _overflow_list"); |
| 6103 } | |
| 6104 | |
| 6105 class CMSRefEnqueueTaskProxy: public AbstractGangTask { | |
| 6106 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; | |
| 6107 EnqueueTask& _task; | |
| 6108 | |
| 6109 public: | |
| 6110 CMSRefEnqueueTaskProxy(EnqueueTask& task) | |
| 6111 : AbstractGangTask("Enqueue reference objects in parallel"), | |
| 6112 _task(task) | |
| 6113 { } | |
| 6114 | |
|
4728
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diff
changeset
|
6115 virtual void work(uint worker_id) |
| 0 | 6116 { |
|
4728
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4128
diff
changeset
|
6117 _task.work(worker_id); |
| 0 | 6118 } |
| 6119 }; | |
| 6120 | |
| 6121 CMSParKeepAliveClosure::CMSParKeepAliveClosure(CMSCollector* collector, | |
|
6725
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6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
6122 MemRegion span, CMSBitMap* bit_map, OopTaskQueue* work_queue): |
| 0 | 6123 _span(span), |
| 6124 _bit_map(bit_map), | |
| 6125 _work_queue(work_queue), | |
|
6725
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coleenp
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6197
diff
changeset
|
6126 _mark_and_push(collector, span, bit_map, work_queue), |
| 0 | 6127 _low_water_mark(MIN2((uint)(work_queue->max_elems()/4), |
| 6128 (uint)(CMSWorkQueueDrainThreshold * ParallelGCThreads))) | |
| 6129 { } | |
| 6130 | |
| 6131 // . see if we can share work_queues with ParNew? XXX | |
| 6132 void CMSRefProcTaskProxy::do_work_steal(int i, | |
| 6133 CMSParDrainMarkingStackClosure* drain, | |
| 6134 CMSParKeepAliveClosure* keep_alive, | |
| 6135 int* seed) { | |
| 6136 OopTaskQueue* work_q = work_queue(i); | |
| 6137 NOT_PRODUCT(int num_steals = 0;) | |
| 6138 oop obj_to_scan; | |
| 6139 | |
| 6140 while (true) { | |
| 6141 // Completely finish any left over work from (an) earlier round(s) | |
| 6142 drain->trim_queue(0); | |
|
679
cea947c8a988
6819891: ParNew: Fix work queue overflow code to deal correctly with +UseCompressedOops
ysr
parents:
628
diff
changeset
|
6143 size_t num_from_overflow_list = MIN2((size_t)(work_q->max_elems() - work_q->size())/4, |
|
cea947c8a988
6819891: ParNew: Fix work queue overflow code to deal correctly with +UseCompressedOops
ysr
parents:
628
diff
changeset
|
6144 (size_t)ParGCDesiredObjsFromOverflowList); |
| 0 | 6145 // Now check if there's any work in the overflow list |
|
1833
8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
jmasa
parents:
1777
diff
changeset
|
6146 // Passing ParallelGCThreads as the third parameter, no_of_gc_threads, |
|
8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
jmasa
parents:
1777
diff
changeset
|
6147 // only affects the number of attempts made to get work from the |
|
8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
jmasa
parents:
1777
diff
changeset
|
6148 // overflow list and does not affect the number of workers. Just |
|
8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
jmasa
parents:
1777
diff
changeset
|
6149 // pass ParallelGCThreads so this behavior is unchanged. |
| 0 | 6150 if (_collector->par_take_from_overflow_list(num_from_overflow_list, |
|
1833
8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
jmasa
parents:
1777
diff
changeset
|
6151 work_q, |
|
8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
jmasa
parents:
1777
diff
changeset
|
6152 ParallelGCThreads)) { |
| 0 | 6153 // Found something in global overflow list; |
| 6154 // not yet ready to go stealing work from others. | |
| 6155 // We'd like to assert(work_q->size() != 0, ...) | |
| 6156 // because we just took work from the overflow list, | |
| 6157 // but of course we can't, since all of that might have | |
| 6158 // been already stolen from us. | |
| 6159 continue; | |
| 6160 } | |
| 6161 // Verify that we have no work before we resort to stealing | |
| 6162 assert(work_q->size() == 0, "Have work, shouldn't steal"); | |
| 6163 // Try to steal from other queues that have work | |
| 6164 if (task_queues()->steal(i, seed, /* reference */ obj_to_scan)) { | |
| 6165 NOT_PRODUCT(num_steals++;) | |
| 6166 assert(obj_to_scan->is_oop(), "Oops, not an oop!"); | |
| 6167 assert(_mark_bit_map->isMarked((HeapWord*)obj_to_scan), "Stole an unmarked oop?"); | |
| 6168 // Do scanning work | |
| 6169 obj_to_scan->oop_iterate(keep_alive); | |
| 6170 // Loop around, finish this work, and try to steal some more | |
| 6171 } else if (terminator()->offer_termination()) { | |
| 6172 break; // nirvana from the infinite cycle | |
| 6173 } | |
| 6174 } | |
| 6175 NOT_PRODUCT( | |
| 6176 if (PrintCMSStatistics != 0) { | |
| 6177 gclog_or_tty->print("\n\t(%d: stole %d oops)", i, num_steals); | |
| 6178 } | |
| 6179 ) | |
| 6180 } | |
| 6181 | |
| 6182 void CMSRefProcTaskExecutor::execute(ProcessTask& task) | |
| 6183 { | |
| 6184 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
|
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6984287: Regularize how GC parallel workers are specified.
jmasa
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diff
changeset
|
6185 FlexibleWorkGang* workers = gch->workers(); |
| 0 | 6186 assert(workers != NULL, "Need parallel worker threads."); |
| 6187 CMSRefProcTaskProxy rp_task(task, &_collector, | |
| 6188 _collector.ref_processor()->span(), | |
| 6189 _collector.markBitMap(), | |
|
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jmasa
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1777
diff
changeset
|
6190 workers, _collector.task_queues()); |
| 0 | 6191 workers->run_task(&rp_task); |
| 6192 } | |
| 6193 | |
| 6194 void CMSRefProcTaskExecutor::execute(EnqueueTask& task) | |
| 6195 { | |
| 6196 | |
| 6197 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
|
1833
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jmasa
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diff
changeset
|
6198 FlexibleWorkGang* workers = gch->workers(); |
| 0 | 6199 assert(workers != NULL, "Need parallel worker threads."); |
| 6200 CMSRefEnqueueTaskProxy enq_task(task); | |
| 6201 workers->run_task(&enq_task); | |
| 6202 } | |
| 6203 | |
| 6204 void CMSCollector::refProcessingWork(bool asynch, bool clear_all_soft_refs) { | |
| 6205 | |
| 6206 ResourceMark rm; | |
| 6207 HandleMark hm; | |
| 6208 | |
| 6209 ReferenceProcessor* rp = ref_processor(); | |
| 6210 assert(rp->span().equals(_span), "Spans should be equal"); | |
|
453
c96030fff130
6684579: SoftReference processing can be made more efficient
ysr
parents:
452
diff
changeset
|
6211 assert(!rp->enqueuing_is_done(), "Enqueuing should not be complete"); |
|
c96030fff130
6684579: SoftReference processing can be made more efficient
ysr
parents:
452
diff
changeset
|
6212 // Process weak references. |
|
457
27a80744a83b
6778647: snap(), snap_policy() should be renamed setup(), setup_policy()
ysr
parents:
453
diff
changeset
|
6213 rp->setup_policy(clear_all_soft_refs); |
|
453
c96030fff130
6684579: SoftReference processing can be made more efficient
ysr
parents:
452
diff
changeset
|
6214 verify_work_stacks_empty(); |
|
c96030fff130
6684579: SoftReference processing can be made more efficient
ysr
parents:
452
diff
changeset
|
6215 |
| 0 | 6216 CMSKeepAliveClosure cmsKeepAliveClosure(this, _span, &_markBitMap, |
|
6725
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
6217 &_markStack, false /* !preclean */); |
| 0 | 6218 CMSDrainMarkingStackClosure cmsDrainMarkingStackClosure(this, |
| 6219 _span, &_markBitMap, &_markStack, | |
|
452
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
6220 &cmsKeepAliveClosure, false /* !preclean */); |
| 0 | 6221 { |
|
20190
0982ec23da03
8043607: Add a GC id as a log decoration similar to PrintGCTimeStamps
brutisso
parents:
17976
diff
changeset
|
6222 GCTraceTime t("weak refs processing", PrintGCDetails, false, _gc_timer_cm, _gc_tracer_cm->gc_id()); |
| 10405 | 6223 |
| 6224 ReferenceProcessorStats stats; | |
| 0 | 6225 if (rp->processing_is_mt()) { |
|
1833
8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
jmasa
parents:
1777
diff
changeset
|
6226 // Set the degree of MT here. If the discovery is done MT, there |
|
8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
jmasa
parents:
1777
diff
changeset
|
6227 // may have been a different number of threads doing the discovery |
|
8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
jmasa
parents:
1777
diff
changeset
|
6228 // and a different number of discovered lists may have Ref objects. |
|
8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
jmasa
parents:
1777
diff
changeset
|
6229 // That is OK as long as the Reference lists are balanced (see |
|
8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
jmasa
parents:
1777
diff
changeset
|
6230 // balance_all_queues() and balance_queues()). |
|
4095
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
parents:
3979
diff
changeset
|
6231 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
parents:
3979
diff
changeset
|
6232 int active_workers = ParallelGCThreads; |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
parents:
3979
diff
changeset
|
6233 FlexibleWorkGang* workers = gch->workers(); |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
parents:
3979
diff
changeset
|
6234 if (workers != NULL) { |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
parents:
3979
diff
changeset
|
6235 active_workers = workers->active_workers(); |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
parents:
3979
diff
changeset
|
6236 // The expectation is that active_workers will have already |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
parents:
3979
diff
changeset
|
6237 // been set to a reasonable value. If it has not been set, |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
parents:
3979
diff
changeset
|
6238 // investigate. |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
parents:
3979
diff
changeset
|
6239 assert(active_workers > 0, "Should have been set during scavenge"); |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
parents:
3979
diff
changeset
|
6240 } |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
parents:
3979
diff
changeset
|
6241 rp->set_active_mt_degree(active_workers); |
| 0 | 6242 CMSRefProcTaskExecutor task_executor(*this); |
| 10405 | 6243 stats = rp->process_discovered_references(&_is_alive_closure, |
| 0 | 6244 &cmsKeepAliveClosure, |
| 6245 &cmsDrainMarkingStackClosure, | |
| 10405 | 6246 &task_executor, |
|
20190
0982ec23da03
8043607: Add a GC id as a log decoration similar to PrintGCTimeStamps
brutisso
parents:
17976
diff
changeset
|
6247 _gc_timer_cm, |
|
0982ec23da03
8043607: Add a GC id as a log decoration similar to PrintGCTimeStamps
brutisso
parents:
17976
diff
changeset
|
6248 _gc_tracer_cm->gc_id()); |
| 0 | 6249 } else { |
| 10405 | 6250 stats = rp->process_discovered_references(&_is_alive_closure, |
| 0 | 6251 &cmsKeepAliveClosure, |
| 6252 &cmsDrainMarkingStackClosure, | |
| 10405 | 6253 NULL, |
|
20190
0982ec23da03
8043607: Add a GC id as a log decoration similar to PrintGCTimeStamps
brutisso
parents:
17976
diff
changeset
|
6254 _gc_timer_cm, |
|
0982ec23da03
8043607: Add a GC id as a log decoration similar to PrintGCTimeStamps
brutisso
parents:
17976
diff
changeset
|
6255 _gc_tracer_cm->gc_id()); |
| 10405 | 6256 } |
| 6257 _gc_tracer_cm->report_gc_reference_stats(stats); | |
| 6258 | |
|
10188
2f50bc369470
8013160: NPG: Remove unnecessary mark stack draining after CodeCache::do_unloading
stefank
parents:
10186
diff
changeset
|
6259 } |
|
2f50bc369470
8013160: NPG: Remove unnecessary mark stack draining after CodeCache::do_unloading
stefank
parents:
10186
diff
changeset
|
6260 |
|
2f50bc369470
8013160: NPG: Remove unnecessary mark stack draining after CodeCache::do_unloading
stefank
parents:
10186
diff
changeset
|
6261 // This is the point where the entire marking should have completed. |
|
2f50bc369470
8013160: NPG: Remove unnecessary mark stack draining after CodeCache::do_unloading
stefank
parents:
10186
diff
changeset
|
6262 verify_work_stacks_empty(); |
| 0 | 6263 |
|
94
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
6264 if (should_unload_classes()) { |
| 0 | 6265 { |
|
20190
0982ec23da03
8043607: Add a GC id as a log decoration similar to PrintGCTimeStamps
brutisso
parents:
17976
diff
changeset
|
6266 GCTraceTime t("class unloading", PrintGCDetails, false, _gc_timer_cm, _gc_tracer_cm->gc_id()); |
| 0 | 6267 |
|
10188
2f50bc369470
8013160: NPG: Remove unnecessary mark stack draining after CodeCache::do_unloading
stefank
parents:
10186
diff
changeset
|
6268 // Unload classes and purge the SystemDictionary. |
| 0 | 6269 bool purged_class = SystemDictionary::do_unloading(&_is_alive_closure); |
| 6270 | |
|
10188
2f50bc369470
8013160: NPG: Remove unnecessary mark stack draining after CodeCache::do_unloading
stefank
parents:
10186
diff
changeset
|
6271 // Unload nmethods. |
|
6787
8966c2d65d96
7200470: KeepAliveClosure not needed in CodeCache::do_unloading
brutisso
parents:
6755
diff
changeset
|
6272 CodeCache::do_unloading(&_is_alive_closure, purged_class); |
| 0 | 6273 |
|
10188
2f50bc369470
8013160: NPG: Remove unnecessary mark stack draining after CodeCache::do_unloading
stefank
parents:
10186
diff
changeset
|
6274 // Prune dead klasses from subklass/sibling/implementor lists. |
|
6725
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
6275 Klass::clean_weak_klass_links(&_is_alive_closure); |
| 0 | 6276 } |
| 6277 | |
| 6278 { | |
|
20190
0982ec23da03
8043607: Add a GC id as a log decoration similar to PrintGCTimeStamps
brutisso
parents:
17976
diff
changeset
|
6279 GCTraceTime t("scrub symbol table", PrintGCDetails, false, _gc_timer_cm, _gc_tracer_cm->gc_id()); |
|
2177
3582bf76420e
6990754: Use native memory and reference counting to implement SymbolTable
coleenp
parents:
2147
diff
changeset
|
6280 // Clean up unreferenced symbols in symbol table. |
|
3582bf76420e
6990754: Use native memory and reference counting to implement SymbolTable
coleenp
parents:
2147
diff
changeset
|
6281 SymbolTable::unlink(); |
| 0 | 6282 } |
|
20278
2c6ef90f030a
8049421: G1 Class Unloading after completing a concurrent mark cycle
stefank
parents:
20268
diff
changeset
|
6283 |
|
2c6ef90f030a
8049421: G1 Class Unloading after completing a concurrent mark cycle
stefank
parents:
20268
diff
changeset
|
6284 { |
|
2c6ef90f030a
8049421: G1 Class Unloading after completing a concurrent mark cycle
stefank
parents:
20268
diff
changeset
|
6285 GCTraceTime t("scrub string table", PrintGCDetails, false, _gc_timer_cm, _gc_tracer_cm->gc_id()); |
|
2c6ef90f030a
8049421: G1 Class Unloading after completing a concurrent mark cycle
stefank
parents:
20268
diff
changeset
|
6286 // Delete entries for dead interned strings. |
|
2c6ef90f030a
8049421: G1 Class Unloading after completing a concurrent mark cycle
stefank
parents:
20268
diff
changeset
|
6287 StringTable::unlink(&_is_alive_closure); |
|
2c6ef90f030a
8049421: G1 Class Unloading after completing a concurrent mark cycle
stefank
parents:
20268
diff
changeset
|
6288 } |
|
2c6ef90f030a
8049421: G1 Class Unloading after completing a concurrent mark cycle
stefank
parents:
20268
diff
changeset
|
6289 } |
|
2c6ef90f030a
8049421: G1 Class Unloading after completing a concurrent mark cycle
stefank
parents:
20268
diff
changeset
|
6290 |
|
2379
b099aaf51bf8
6962931: move interned strings out of the perm gen
jcoomes
parents:
2369
diff
changeset
|
6291 |
| 0 | 6292 // Restore any preserved marks as a result of mark stack or |
| 6293 // work queue overflow | |
| 6294 restore_preserved_marks_if_any(); // done single-threaded for now | |
| 6295 | |
| 6296 rp->set_enqueuing_is_done(true); | |
| 6297 if (rp->processing_is_mt()) { | |
|
1833
8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
jmasa
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1777
diff
changeset
|
6298 rp->balance_all_queues(); |
| 0 | 6299 CMSRefProcTaskExecutor task_executor(*this); |
| 6300 rp->enqueue_discovered_references(&task_executor); | |
| 6301 } else { | |
| 6302 rp->enqueue_discovered_references(NULL); | |
| 6303 } | |
| 6304 rp->verify_no_references_recorded(); | |
| 6305 assert(!rp->discovery_enabled(), "should have been disabled"); | |
| 6306 } | |
| 6307 | |
| 6308 #ifndef PRODUCT | |
| 6309 void CMSCollector::check_correct_thread_executing() { | |
| 6310 Thread* t = Thread::current(); | |
| 6311 // Only the VM thread or the CMS thread should be here. | |
| 6312 assert(t->is_ConcurrentGC_thread() || t->is_VM_thread(), | |
| 6313 "Unexpected thread type"); | |
| 6314 // If this is the vm thread, the foreground process | |
| 6315 // should not be waiting. Note that _foregroundGCIsActive is | |
| 6316 // true while the foreground collector is waiting. | |
| 6317 if (_foregroundGCShouldWait) { | |
| 6318 // We cannot be the VM thread | |
| 6319 assert(t->is_ConcurrentGC_thread(), | |
| 6320 "Should be CMS thread"); | |
| 6321 } else { | |
| 6322 // We can be the CMS thread only if we are in a stop-world | |
| 6323 // phase of CMS collection. | |
| 6324 if (t->is_ConcurrentGC_thread()) { | |
| 6325 assert(_collectorState == InitialMarking || | |
| 6326 _collectorState == FinalMarking, | |
| 6327 "Should be a stop-world phase"); | |
| 6328 // The CMS thread should be holding the CMS_token. | |
| 6329 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 6330 "Potential interference with concurrently " | |
| 6331 "executing VM thread"); | |
| 6332 } | |
| 6333 } | |
| 6334 } | |
| 6335 #endif | |
| 6336 | |
| 6337 void CMSCollector::sweep(bool asynch) { | |
| 6338 assert(_collectorState == Sweeping, "just checking"); | |
| 6339 check_correct_thread_executing(); | |
| 6340 verify_work_stacks_empty(); | |
| 6341 verify_overflow_empty(); | |
|
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6342 increment_sweep_count(); |
|
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6343 TraceCMSMemoryManagerStats tms(_collectorState,GenCollectedHeap::heap()->gc_cause()); |
|
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6344 |
|
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6345 _inter_sweep_timer.stop(); |
|
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|
6346 _inter_sweep_estimate.sample(_inter_sweep_timer.seconds()); |
| 0 | 6347 size_policy()->avg_cms_free_at_sweep()->sample(_cmsGen->free()); |
| 6348 | |
|
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6349 assert(!_intra_sweep_timer.is_active(), "Should not be active"); |
|
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6350 _intra_sweep_timer.reset(); |
|
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|
6351 _intra_sweep_timer.start(); |
| 0 | 6352 if (asynch) { |
| 6353 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
|
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6354 CMSPhaseAccounting pa(this, "sweep", _gc_tracer_cm->gc_id(), !PrintGCDetails); |
|
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|
6355 // First sweep the old gen |
| 0 | 6356 { |
| 6357 CMSTokenSyncWithLocks ts(true, _cmsGen->freelistLock(), | |
| 6358 bitMapLock()); | |
| 6359 sweepWork(_cmsGen, asynch); | |
| 6360 } | |
| 6361 | |
| 6362 // Update Universe::_heap_*_at_gc figures. | |
| 6363 // We need all the free list locks to make the abstract state | |
| 6364 // transition from Sweeping to Resetting. See detailed note | |
| 6365 // further below. | |
| 6366 { | |
|
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6367 CMSTokenSyncWithLocks ts(true, _cmsGen->freelistLock()); |
| 0 | 6368 // Update heap occupancy information which is used as |
| 6369 // input to soft ref clearing policy at the next gc. | |
| 6370 Universe::update_heap_info_at_gc(); | |
| 6371 _collectorState = Resizing; | |
| 6372 } | |
| 6373 } else { | |
| 6374 // already have needed locks | |
| 6375 sweepWork(_cmsGen, asynch); | |
| 6376 // Update heap occupancy information which is used as | |
| 6377 // input to soft ref clearing policy at the next gc. | |
| 6378 Universe::update_heap_info_at_gc(); | |
| 6379 _collectorState = Resizing; | |
| 6380 } | |
| 6381 verify_work_stacks_empty(); | |
| 6382 verify_overflow_empty(); | |
| 6383 | |
|
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6384 if (should_unload_classes()) { |
|
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6385 // Delay purge to the beginning of the next safepoint. Metaspace::contains |
|
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6386 // requires that the virtual spaces are stable and not deleted. |
|
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|
6387 ClassLoaderDataGraph::set_should_purge(true); |
|
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6388 } |
|
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6389 |
|
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6390 _intra_sweep_timer.stop(); |
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6391 _intra_sweep_estimate.sample(_intra_sweep_timer.seconds()); |
|
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6392 |
|
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|
6393 _inter_sweep_timer.reset(); |
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|
6394 _inter_sweep_timer.start(); |
| 0 | 6395 |
| 4911 | 6396 // We need to use a monotonically non-deccreasing time in ms |
| 6397 // or we will see time-warp warnings and os::javaTimeMillis() | |
| 6398 // does not guarantee monotonicity. | |
| 6399 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; | |
| 6400 update_time_of_last_gc(now); | |
| 0 | 6401 |
| 6402 // NOTE on abstract state transitions: | |
| 6403 // Mutators allocate-live and/or mark the mod-union table dirty | |
| 6404 // based on the state of the collection. The former is done in | |
| 6405 // the interval [Marking, Sweeping] and the latter in the interval | |
| 6406 // [Marking, Sweeping). Thus the transitions into the Marking state | |
| 6407 // and out of the Sweeping state must be synchronously visible | |
| 6408 // globally to the mutators. | |
| 6409 // The transition into the Marking state happens with the world | |
| 6410 // stopped so the mutators will globally see it. Sweeping is | |
| 6411 // done asynchronously by the background collector so the transition | |
| 6412 // from the Sweeping state to the Resizing state must be done | |
| 6413 // under the freelistLock (as is the check for whether to | |
| 6414 // allocate-live and whether to dirty the mod-union table). | |
| 6415 assert(_collectorState == Resizing, "Change of collector state to" | |
| 6416 " Resizing must be done under the freelistLocks (plural)"); | |
| 6417 | |
|
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|
6418 // Now that sweeping has been completed, we clear |
|
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|
6419 // the incremental_collection_failed flag, |
| 0 | 6420 // thus inviting a younger gen collection to promote into |
| 6421 // this generation. If such a promotion may still fail, | |
| 6422 // the flag will be set again when a young collection is | |
| 6423 // attempted. | |
| 6424 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
|
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|
6425 gch->clear_incremental_collection_failed(); // Worth retrying as fresh space may have been freed up |
| 0 | 6426 gch->update_full_collections_completed(_collection_count_start); |
| 6427 } | |
| 6428 | |
| 6429 // FIX ME!!! Looks like this belongs in CFLSpace, with | |
| 6430 // CMSGen merely delegating to it. | |
| 6431 void ConcurrentMarkSweepGeneration::setNearLargestChunk() { | |
|
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|
6432 double nearLargestPercent = FLSLargestBlockCoalesceProximity; |
| 0 | 6433 HeapWord* minAddr = _cmsSpace->bottom(); |
| 6434 HeapWord* largestAddr = | |
|
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|
6435 (HeapWord*) _cmsSpace->dictionary()->find_largest_dict(); |
|
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|
6436 if (largestAddr == NULL) { |
| 0 | 6437 // The dictionary appears to be empty. In this case |
| 6438 // try to coalesce at the end of the heap. | |
| 6439 largestAddr = _cmsSpace->end(); | |
| 6440 } | |
| 6441 size_t largestOffset = pointer_delta(largestAddr, minAddr); | |
| 6442 size_t nearLargestOffset = | |
| 6443 (size_t)((double)largestOffset * nearLargestPercent) - MinChunkSize; | |
|
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|
6444 if (PrintFLSStatistics != 0) { |
|
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|
6445 gclog_or_tty->print_cr( |
|
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|
6446 "CMS: Large Block: " PTR_FORMAT ";" |
|
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|
6447 " Proximity: " PTR_FORMAT " -> " PTR_FORMAT, |
|
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|
6448 largestAddr, |
|
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|
6449 _cmsSpace->nearLargestChunk(), minAddr + nearLargestOffset); |
|
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|
6450 } |
| 0 | 6451 _cmsSpace->set_nearLargestChunk(minAddr + nearLargestOffset); |
| 6452 } | |
| 6453 | |
| 6454 bool ConcurrentMarkSweepGeneration::isNearLargestChunk(HeapWord* addr) { | |
| 6455 return addr >= _cmsSpace->nearLargestChunk(); | |
| 6456 } | |
| 6457 | |
| 6458 FreeChunk* ConcurrentMarkSweepGeneration::find_chunk_at_end() { | |
| 6459 return _cmsSpace->find_chunk_at_end(); | |
| 6460 } | |
| 6461 | |
| 6462 void ConcurrentMarkSweepGeneration::update_gc_stats(int current_level, | |
| 6463 bool full) { | |
| 6464 // The next lower level has been collected. Gather any statistics | |
| 6465 // that are of interest at this point. | |
| 6466 if (!full && (current_level + 1) == level()) { | |
| 6467 // Gather statistics on the young generation collection. | |
| 6468 collector()->stats().record_gc0_end(used()); | |
| 6469 } | |
| 6470 } | |
| 6471 | |
| 6472 CMSAdaptiveSizePolicy* ConcurrentMarkSweepGeneration::size_policy() { | |
| 6473 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 6474 assert(gch->kind() == CollectedHeap::GenCollectedHeap, | |
| 6475 "Wrong type of heap"); | |
| 6476 CMSAdaptiveSizePolicy* sp = (CMSAdaptiveSizePolicy*) | |
| 6477 gch->gen_policy()->size_policy(); | |
| 6478 assert(sp->is_gc_cms_adaptive_size_policy(), | |
| 6479 "Wrong type of size policy"); | |
| 6480 return sp; | |
| 6481 } | |
| 6482 | |
| 6483 void ConcurrentMarkSweepGeneration::rotate_debug_collection_type() { | |
| 6484 if (PrintGCDetails && Verbose) { | |
| 6485 gclog_or_tty->print("Rotate from %d ", _debug_collection_type); | |
| 6486 } | |
| 6487 _debug_collection_type = (CollectionTypes) (_debug_collection_type + 1); | |
| 6488 _debug_collection_type = | |
| 6489 (CollectionTypes) (_debug_collection_type % Unknown_collection_type); | |
| 6490 if (PrintGCDetails && Verbose) { | |
| 6491 gclog_or_tty->print_cr("to %d ", _debug_collection_type); | |
| 6492 } | |
| 6493 } | |
| 6494 | |
| 6495 void CMSCollector::sweepWork(ConcurrentMarkSweepGeneration* gen, | |
| 6496 bool asynch) { | |
| 6497 // We iterate over the space(s) underlying this generation, | |
| 6498 // checking the mark bit map to see if the bits corresponding | |
| 6499 // to specific blocks are marked or not. Blocks that are | |
| 6500 // marked are live and are not swept up. All remaining blocks | |
| 6501 // are swept up, with coalescing on-the-fly as we sweep up | |
| 6502 // contiguous free and/or garbage blocks: | |
| 6503 // We need to ensure that the sweeper synchronizes with allocators | |
| 6504 // and stop-the-world collectors. In particular, the following | |
| 6505 // locks are used: | |
| 6506 // . CMS token: if this is held, a stop the world collection cannot occur | |
| 6507 // . freelistLock: if this is held no allocation can occur from this | |
| 6508 // generation by another thread | |
| 6509 // . bitMapLock: if this is held, no other thread can access or update | |
| 6510 // | |
| 6511 | |
| 6512 // Note that we need to hold the freelistLock if we use | |
| 6513 // block iterate below; else the iterator might go awry if | |
| 6514 // a mutator (or promotion) causes block contents to change | |
| 6515 // (for instance if the allocator divvies up a block). | |
| 6516 // If we hold the free list lock, for all practical purposes | |
| 6517 // young generation GC's can't occur (they'll usually need to | |
| 6518 // promote), so we might as well prevent all young generation | |
| 6519 // GC's while we do a sweeping step. For the same reason, we might | |
| 6520 // as well take the bit map lock for the entire duration | |
| 6521 | |
| 6522 // check that we hold the requisite locks | |
| 6523 assert(have_cms_token(), "Should hold cms token"); | |
| 6524 assert( (asynch && ConcurrentMarkSweepThread::cms_thread_has_cms_token()) | |
| 6525 || (!asynch && ConcurrentMarkSweepThread::vm_thread_has_cms_token()), | |
| 6526 "Should possess CMS token to sweep"); | |
| 6527 assert_lock_strong(gen->freelistLock()); | |
| 6528 assert_lock_strong(bitMapLock()); | |
| 6529 | |
|
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|
6530 assert(!_inter_sweep_timer.is_active(), "Was switched off in an outer context"); |
|
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|
6531 assert(_intra_sweep_timer.is_active(), "Was switched on in an outer context"); |
|
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|
6532 gen->cmsSpace()->beginSweepFLCensus((float)(_inter_sweep_timer.seconds()), |
|
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|
6533 _inter_sweep_estimate.padded_average(), |
|
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|
6534 _intra_sweep_estimate.padded_average()); |
| 0 | 6535 gen->setNearLargestChunk(); |
| 6536 | |
| 6537 { | |
| 6538 SweepClosure sweepClosure(this, gen, &_markBitMap, | |
| 6539 CMSYield && asynch); | |
| 6540 gen->cmsSpace()->blk_iterate_careful(&sweepClosure); | |
| 6541 // We need to free-up/coalesce garbage/blocks from a | |
| 6542 // co-terminal free run. This is done in the SweepClosure | |
| 6543 // destructor; so, do not remove this scope, else the | |
| 6544 // end-of-sweep-census below will be off by a little bit. | |
| 6545 } | |
| 6546 gen->cmsSpace()->sweep_completed(); | |
|
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|
6547 gen->cmsSpace()->endSweepFLCensus(sweep_count()); |
|
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|
6548 if (should_unload_classes()) { // unloaded classes this cycle, |
|
0834225a7916
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|
6549 _concurrent_cycles_since_last_unload = 0; // ... reset count |
|
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|
6550 } else { // did not unload classes, |
|
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|
6551 _concurrent_cycles_since_last_unload++; // ... increment count |
|
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|
6552 } |
| 0 | 6553 } |
| 6554 | |
| 6555 // Reset CMS data structures (for now just the marking bit map) | |
| 6556 // preparatory for the next cycle. | |
| 6557 void CMSCollector::reset(bool asynch) { | |
| 6558 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 6559 CMSAdaptiveSizePolicy* sp = size_policy(); | |
| 6560 AdaptiveSizePolicyOutput(sp, gch->total_collections()); | |
| 6561 if (asynch) { | |
| 6562 CMSTokenSyncWithLocks ts(true, bitMapLock()); | |
| 6563 | |
| 6564 // If the state is not "Resetting", the foreground thread | |
| 6565 // has done a collection and the resetting. | |
| 6566 if (_collectorState != Resetting) { | |
| 6567 assert(_collectorState == Idling, "The state should only change" | |
| 6568 " because the foreground collector has finished the collection"); | |
| 6569 return; | |
| 6570 } | |
| 6571 | |
| 6572 // Clear the mark bitmap (no grey objects to start with) | |
| 6573 // for the next cycle. | |
| 6574 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
|
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|
6575 CMSPhaseAccounting cmspa(this, "reset", _gc_tracer_cm->gc_id(), !PrintGCDetails); |
| 0 | 6576 |
| 6577 HeapWord* curAddr = _markBitMap.startWord(); | |
| 6578 while (curAddr < _markBitMap.endWord()) { | |
| 6579 size_t remaining = pointer_delta(_markBitMap.endWord(), curAddr); | |
| 6580 MemRegion chunk(curAddr, MIN2(CMSBitMapYieldQuantum, remaining)); | |
| 6581 _markBitMap.clear_large_range(chunk); | |
| 6582 if (ConcurrentMarkSweepThread::should_yield() && | |
| 6583 !foregroundGCIsActive() && | |
| 6584 CMSYield) { | |
| 6585 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 6586 "CMS thread should hold CMS token"); | |
| 6587 assert_lock_strong(bitMapLock()); | |
| 6588 bitMapLock()->unlock(); | |
| 6589 ConcurrentMarkSweepThread::desynchronize(true); | |
| 6590 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 6591 stopTimer(); | |
| 6592 if (PrintCMSStatistics != 0) { | |
| 6593 incrementYields(); | |
| 6594 } | |
| 6595 icms_wait(); | |
| 6596 | |
| 6597 // See the comment in coordinator_yield() | |
| 6598 for (unsigned i = 0; i < CMSYieldSleepCount && | |
|
113
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|
6599 ConcurrentMarkSweepThread::should_yield() && |
|
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|
6600 !CMSCollector::foregroundGCIsActive(); ++i) { |
| 0 | 6601 os::sleep(Thread::current(), 1, false); |
| 6602 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 6603 } | |
| 6604 | |
| 6605 ConcurrentMarkSweepThread::synchronize(true); | |
| 6606 bitMapLock()->lock_without_safepoint_check(); | |
| 6607 startTimer(); | |
| 6608 } | |
| 6609 curAddr = chunk.end(); | |
| 6610 } | |
|
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|
6611 // A successful mostly concurrent collection has been done. |
|
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|
6612 // Because only the full (i.e., concurrent mode failure) collections |
|
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|
6613 // are being measured for gc overhead limits, clean the "near" flag |
|
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|
6614 // and count. |
|
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|
6615 sp->reset_gc_overhead_limit_count(); |
| 0 | 6616 _collectorState = Idling; |
| 6617 } else { | |
| 6618 // already have the lock | |
| 6619 assert(_collectorState == Resetting, "just checking"); | |
| 6620 assert_lock_strong(bitMapLock()); | |
| 6621 _markBitMap.clear_all(); | |
| 6622 _collectorState = Idling; | |
| 6623 } | |
| 6624 | |
| 6625 // Stop incremental mode after a cycle completes, so that any future cycles | |
| 6626 // are triggered by allocation. | |
| 6627 stop_icms(); | |
| 6628 | |
| 6629 NOT_PRODUCT( | |
| 6630 if (RotateCMSCollectionTypes) { | |
| 6631 _cmsGen->rotate_debug_collection_type(); | |
| 6632 } | |
| 6633 ) | |
| 10405 | 6634 |
| 6635 register_gc_end(); | |
| 0 | 6636 } |
| 6637 | |
|
6064
9d679effd28c
7166894: Add gc cause to GC logging for all collectors
brutisso
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6028
diff
changeset
|
6638 void CMSCollector::do_CMS_operation(CMS_op_type op, GCCause::Cause gc_cause) { |
| 0 | 6639 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); |
|
20190
0982ec23da03
8043607: Add a GC id as a log decoration similar to PrintGCTimeStamps
brutisso
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17976
diff
changeset
|
6640 GCTraceTime t(GCCauseString("GC", gc_cause), PrintGC, !PrintGCDetails, NULL, _gc_tracer_cm->gc_id()); |
| 0 | 6641 TraceCollectorStats tcs(counters()); |
| 6642 | |
| 6643 switch (op) { | |
| 6644 case CMS_op_checkpointRootsInitial: { | |
|
2125
7246a374a9f2
6458402: 3 jvmti tests fail with CMS and +ExplicitGCInvokesConcurrent
kamg
parents:
1994
diff
changeset
|
6645 SvcGCMarker sgcm(SvcGCMarker::OTHER); |
| 0 | 6646 checkpointRootsInitial(true); // asynch |
| 6647 if (PrintGC) { | |
| 6648 _cmsGen->printOccupancy("initial-mark"); | |
| 6649 } | |
| 6650 break; | |
| 6651 } | |
| 6652 case CMS_op_checkpointRootsFinal: { | |
|
2125
7246a374a9f2
6458402: 3 jvmti tests fail with CMS and +ExplicitGCInvokesConcurrent
kamg
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1994
diff
changeset
|
6653 SvcGCMarker sgcm(SvcGCMarker::OTHER); |
| 0 | 6654 checkpointRootsFinal(true, // asynch |
| 6655 false, // !clear_all_soft_refs | |
| 6656 false); // !init_mark_was_synchronous | |
| 6657 if (PrintGC) { | |
| 6658 _cmsGen->printOccupancy("remark"); | |
| 6659 } | |
| 6660 break; | |
| 6661 } | |
| 6662 default: | |
| 6663 fatal("No such CMS_op"); | |
| 6664 } | |
| 6665 } | |
| 6666 | |
| 6667 #ifndef PRODUCT | |
| 6668 size_t const CMSCollector::skip_header_HeapWords() { | |
| 6669 return FreeChunk::header_size(); | |
| 6670 } | |
| 6671 | |
| 6672 // Try and collect here conditions that should hold when | |
| 6673 // CMS thread is exiting. The idea is that the foreground GC | |
| 6674 // thread should not be blocked if it wants to terminate | |
| 6675 // the CMS thread and yet continue to run the VM for a while | |
| 6676 // after that. | |
| 6677 void CMSCollector::verify_ok_to_terminate() const { | |
| 6678 assert(Thread::current()->is_ConcurrentGC_thread(), | |
| 6679 "should be called by CMS thread"); | |
| 6680 assert(!_foregroundGCShouldWait, "should be false"); | |
| 6681 // We could check here that all the various low-level locks | |
| 6682 // are not held by the CMS thread, but that is overkill; see | |
| 6683 // also CMSThread::verify_ok_to_terminate() where the CGC_lock | |
| 6684 // is checked. | |
| 6685 } | |
| 6686 #endif | |
| 6687 | |
| 6688 size_t CMSCollector::block_size_using_printezis_bits(HeapWord* addr) const { | |
|
453
c96030fff130
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452
diff
changeset
|
6689 assert(_markBitMap.isMarked(addr) && _markBitMap.isMarked(addr + 1), |
|
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diff
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|
6690 "missing Printezis mark?"); |
| 0 | 6691 HeapWord* nextOneAddr = _markBitMap.getNextMarkedWordAddress(addr + 2); |
| 6692 size_t size = pointer_delta(nextOneAddr + 1, addr); | |
| 6693 assert(size == CompactibleFreeListSpace::adjustObjectSize(size), | |
| 6694 "alignment problem"); | |
| 6695 assert(size >= 3, "Necessary for Printezis marks to work"); | |
| 6696 return size; | |
| 6697 } | |
| 6698 | |
| 6699 // A variant of the above (block_size_using_printezis_bits()) except | |
| 6700 // that we return 0 if the P-bits are not yet set. | |
| 6701 size_t CMSCollector::block_size_if_printezis_bits(HeapWord* addr) const { | |
|
2226
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2177
diff
changeset
|
6702 if (_markBitMap.isMarked(addr + 1)) { |
|
c5a923563727
6912621: iCMS: Error: assert(_markBitMap.isMarked(addr + 1),"Missing Printezis bit?")
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diff
changeset
|
6703 assert(_markBitMap.isMarked(addr), "P-bit can be set only for marked objects"); |
| 0 | 6704 HeapWord* nextOneAddr = _markBitMap.getNextMarkedWordAddress(addr + 2); |
| 6705 size_t size = pointer_delta(nextOneAddr + 1, addr); | |
| 6706 assert(size == CompactibleFreeListSpace::adjustObjectSize(size), | |
| 6707 "alignment problem"); | |
| 6708 assert(size >= 3, "Necessary for Printezis marks to work"); | |
| 6709 return size; | |
|
2226
c5a923563727
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2177
diff
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|
6710 } |
|
c5a923563727
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2177
diff
changeset
|
6711 return 0; |
| 0 | 6712 } |
| 6713 | |
| 6714 HeapWord* CMSCollector::next_card_start_after_block(HeapWord* addr) const { | |
| 6715 size_t sz = 0; | |
| 6716 oop p = (oop)addr; | |
|
6725
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diff
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|
6717 if (p->klass_or_null() != NULL) { |
| 0 | 6718 sz = CompactibleFreeListSpace::adjustObjectSize(p->size()); |
| 6719 } else { | |
| 6720 sz = block_size_using_printezis_bits(addr); | |
| 6721 } | |
| 6722 assert(sz > 0, "size must be nonzero"); | |
| 6723 HeapWord* next_block = addr + sz; | |
| 6724 HeapWord* next_card = (HeapWord*)round_to((uintptr_t)next_block, | |
| 6725 CardTableModRefBS::card_size); | |
| 6726 assert(round_down((uintptr_t)addr, CardTableModRefBS::card_size) < | |
| 6727 round_down((uintptr_t)next_card, CardTableModRefBS::card_size), | |
| 6728 "must be different cards"); | |
| 6729 return next_card; | |
| 6730 } | |
| 6731 | |
| 6732 | |
| 6733 // CMS Bit Map Wrapper ///////////////////////////////////////// | |
| 6734 | |
| 6735 // Construct a CMS bit map infrastructure, but don't create the | |
| 6736 // bit vector itself. That is done by a separate call CMSBitMap::allocate() | |
| 6737 // further below. | |
| 6738 CMSBitMap::CMSBitMap(int shifter, int mutex_rank, const char* mutex_name): | |
|
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diff
changeset
|
6739 _bm(), |
| 0 | 6740 _shifter(shifter), |
| 6741 _lock(mutex_rank >= 0 ? new Mutex(mutex_rank, mutex_name, true) : NULL) | |
| 6742 { | |
| 6743 _bmStartWord = 0; | |
| 6744 _bmWordSize = 0; | |
| 6745 } | |
| 6746 | |
| 6747 bool CMSBitMap::allocate(MemRegion mr) { | |
| 6748 _bmStartWord = mr.start(); | |
| 6749 _bmWordSize = mr.word_size(); | |
| 6750 ReservedSpace brs(ReservedSpace::allocation_align_size_up( | |
| 6751 (_bmWordSize >> (_shifter + LogBitsPerByte)) + 1)); | |
| 6752 if (!brs.is_reserved()) { | |
| 6753 warning("CMS bit map allocation failure"); | |
| 6754 return false; | |
| 6755 } | |
| 6756 // For now we'll just commit all of the bit map up fromt. | |
| 6757 // Later on we'll try to be more parsimonious with swap. | |
| 6758 if (!_virtual_space.initialize(brs, brs.size())) { | |
| 6759 warning("CMS bit map backing store failure"); | |
| 6760 return false; | |
| 6761 } | |
| 6762 assert(_virtual_space.committed_size() == brs.size(), | |
| 6763 "didn't reserve backing store for all of CMS bit map?"); | |
|
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|
6764 _bm.set_map((BitMap::bm_word_t*)_virtual_space.low()); |
| 0 | 6765 assert(_virtual_space.committed_size() << (_shifter + LogBitsPerByte) >= |
| 6766 _bmWordSize, "inconsistency in bit map sizing"); | |
| 6767 _bm.set_size(_bmWordSize >> _shifter); | |
| 6768 | |
| 6769 // bm.clear(); // can we rely on getting zero'd memory? verify below | |
| 6770 assert(isAllClear(), | |
| 6771 "Expected zero'd memory from ReservedSpace constructor"); | |
| 6772 assert(_bm.size() == heapWordDiffToOffsetDiff(sizeInWords()), | |
| 6773 "consistency check"); | |
| 6774 return true; | |
| 6775 } | |
| 6776 | |
| 6777 void CMSBitMap::dirty_range_iterate_clear(MemRegion mr, MemRegionClosure* cl) { | |
| 6778 HeapWord *next_addr, *end_addr, *last_addr; | |
| 6779 assert_locked(); | |
| 6780 assert(covers(mr), "out-of-range error"); | |
| 6781 // XXX assert that start and end are appropriately aligned | |
| 6782 for (next_addr = mr.start(), end_addr = mr.end(); | |
| 6783 next_addr < end_addr; next_addr = last_addr) { | |
| 6784 MemRegion dirty_region = getAndClearMarkedRegion(next_addr, end_addr); | |
| 6785 last_addr = dirty_region.end(); | |
| 6786 if (!dirty_region.is_empty()) { | |
| 6787 cl->do_MemRegion(dirty_region); | |
| 6788 } else { | |
| 6789 assert(last_addr == end_addr, "program logic"); | |
| 6790 return; | |
| 6791 } | |
| 6792 } | |
| 6793 } | |
| 6794 | |
|
9076
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8011872: Include Bit Map addresses in the hs_err files
stefank
parents:
9072
diff
changeset
|
6795 void CMSBitMap::print_on_error(outputStream* st, const char* prefix) const { |
|
7b835924c31c
8011872: Include Bit Map addresses in the hs_err files
stefank
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9072
diff
changeset
|
6796 _bm.print_on_error(st, prefix); |
|
7b835924c31c
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stefank
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9072
diff
changeset
|
6797 } |
|
7b835924c31c
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9072
diff
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|
6798 |
| 0 | 6799 #ifndef PRODUCT |
| 6800 void CMSBitMap::assert_locked() const { | |
| 6801 CMSLockVerifier::assert_locked(lock()); | |
| 6802 } | |
| 6803 | |
| 6804 bool CMSBitMap::covers(MemRegion mr) const { | |
| 6805 // assert(_bm.map() == _virtual_space.low(), "map inconsistency"); | |
| 6806 assert((size_t)_bm.size() == (_bmWordSize >> _shifter), | |
| 6807 "size inconsistency"); | |
| 6808 return (mr.start() >= _bmStartWord) && | |
| 6809 (mr.end() <= endWord()); | |
| 6810 } | |
| 6811 | |
| 6812 bool CMSBitMap::covers(HeapWord* start, size_t size) const { | |
| 6813 return (start >= _bmStartWord && (start + size) <= endWord()); | |
| 6814 } | |
| 6815 | |
| 6816 void CMSBitMap::verifyNoOneBitsInRange(HeapWord* left, HeapWord* right) { | |
| 6817 // verify that there are no 1 bits in the interval [left, right) | |
| 6818 FalseBitMapClosure falseBitMapClosure; | |
| 6819 iterate(&falseBitMapClosure, left, right); | |
| 6820 } | |
| 6821 | |
| 6822 void CMSBitMap::region_invariant(MemRegion mr) | |
| 6823 { | |
| 6824 assert_locked(); | |
| 6825 // mr = mr.intersection(MemRegion(_bmStartWord, _bmWordSize)); | |
| 6826 assert(!mr.is_empty(), "unexpected empty region"); | |
| 6827 assert(covers(mr), "mr should be covered by bit map"); | |
| 6828 // convert address range into offset range | |
| 6829 size_t start_ofs = heapWordToOffset(mr.start()); | |
| 6830 // Make sure that end() is appropriately aligned | |
| 6831 assert(mr.end() == (HeapWord*)round_to((intptr_t)mr.end(), | |
| 6832 (1 << (_shifter+LogHeapWordSize))), | |
| 6833 "Misaligned mr.end()"); | |
| 6834 size_t end_ofs = heapWordToOffset(mr.end()); | |
| 6835 assert(end_ofs > start_ofs, "Should mark at least one bit"); | |
| 6836 } | |
| 6837 | |
| 6838 #endif | |
| 6839 | |
| 6840 bool CMSMarkStack::allocate(size_t size) { | |
| 6841 // allocate a stack of the requisite depth | |
| 6842 ReservedSpace rs(ReservedSpace::allocation_align_size_up( | |
| 6843 size * sizeof(oop))); | |
| 6844 if (!rs.is_reserved()) { | |
| 6845 warning("CMSMarkStack allocation failure"); | |
| 6846 return false; | |
| 6847 } | |
| 6848 if (!_virtual_space.initialize(rs, rs.size())) { | |
| 6849 warning("CMSMarkStack backing store failure"); | |
| 6850 return false; | |
| 6851 } | |
| 6852 assert(_virtual_space.committed_size() == rs.size(), | |
| 6853 "didn't reserve backing store for all of CMS stack?"); | |
| 6854 _base = (oop*)(_virtual_space.low()); | |
| 6855 _index = 0; | |
| 6856 _capacity = size; | |
| 6857 NOT_PRODUCT(_max_depth = 0); | |
| 6858 return true; | |
| 6859 } | |
| 6860 | |
| 6861 // XXX FIX ME !!! In the MT case we come in here holding a | |
| 6862 // leaf lock. For printing we need to take a further lock | |
| 6863 // which has lower rank. We need to recallibrate the two | |
| 6864 // lock-ranks involved in order to be able to rpint the | |
| 6865 // messages below. (Or defer the printing to the caller. | |
| 6866 // For now we take the expedient path of just disabling the | |
| 6867 // messages for the problematic case.) | |
| 6868 void CMSMarkStack::expand() { | |
| 1284 | 6869 assert(_capacity <= MarkStackSizeMax, "stack bigger than permitted"); |
| 6870 if (_capacity == MarkStackSizeMax) { | |
| 0 | 6871 if (_hit_limit++ == 0 && !CMSConcurrentMTEnabled && PrintGCDetails) { |
| 6872 // We print a warning message only once per CMS cycle. | |
| 6873 gclog_or_tty->print_cr(" (benign) Hit CMSMarkStack max size limit"); | |
| 6874 } | |
| 6875 return; | |
| 6876 } | |
| 6877 // Double capacity if possible | |
| 1284 | 6878 size_t new_capacity = MIN2(_capacity*2, MarkStackSizeMax); |
| 0 | 6879 // Do not give up existing stack until we have managed to |
| 6880 // get the double capacity that we desired. | |
| 6881 ReservedSpace rs(ReservedSpace::allocation_align_size_up( | |
| 6882 new_capacity * sizeof(oop))); | |
| 6883 if (rs.is_reserved()) { | |
| 6884 // Release the backing store associated with old stack | |
| 6885 _virtual_space.release(); | |
| 6886 // Reinitialize virtual space for new stack | |
| 6887 if (!_virtual_space.initialize(rs, rs.size())) { | |
| 6888 fatal("Not enough swap for expanded marking stack"); | |
| 6889 } | |
| 6890 _base = (oop*)(_virtual_space.low()); | |
| 6891 _index = 0; | |
| 6892 _capacity = new_capacity; | |
| 6893 } else if (_failed_double++ == 0 && !CMSConcurrentMTEnabled && PrintGCDetails) { | |
| 6894 // Failed to double capacity, continue; | |
| 6895 // we print a detail message only once per CMS cycle. | |
| 6896 gclog_or_tty->print(" (benign) Failed to expand marking stack from "SIZE_FORMAT"K to " | |
| 6897 SIZE_FORMAT"K", | |
| 6898 _capacity / K, new_capacity / K); | |
| 6899 } | |
| 6900 } | |
| 6901 | |
| 6902 | |
| 6903 // Closures | |
| 6904 // XXX: there seems to be a lot of code duplication here; | |
| 6905 // should refactor and consolidate common code. | |
| 6906 | |
| 6907 // This closure is used to mark refs into the CMS generation in | |
| 6908 // the CMS bit map. Called at the first checkpoint. This closure | |
| 6909 // assumes that we do not need to re-mark dirty cards; if the CMS | |
|
6725
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6964458: Reimplement class meta-data storage to use native memory
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6197
diff
changeset
|
6910 // generation on which this is used is not an oldest |
| 0 | 6911 // generation then this will lose younger_gen cards! |
| 6912 | |
| 6913 MarkRefsIntoClosure::MarkRefsIntoClosure( | |
|
994
753cf9794df9
6885169: merge of 4957990 and 6863023 causes conflict on do_nmethods
jrose
parents:
993
diff
changeset
|
6914 MemRegion span, CMSBitMap* bitMap): |
| 0 | 6915 _span(span), |
|
994
753cf9794df9
6885169: merge of 4957990 and 6863023 causes conflict on do_nmethods
jrose
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993
diff
changeset
|
6916 _bitMap(bitMap) |
| 0 | 6917 { |
| 6918 assert(_ref_processor == NULL, "deliberately left NULL"); | |
| 6919 assert(_bitMap->covers(_span), "_bitMap/_span mismatch"); | |
| 6920 } | |
| 6921 | |
|
113
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coleenp
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94
diff
changeset
|
6922 void MarkRefsIntoClosure::do_oop(oop obj) { |
| 0 | 6923 // if p points into _span, then mark corresponding bit in _markBitMap |
|
113
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94
diff
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|
6924 assert(obj->is_oop(), "expected an oop"); |
|
ba764ed4b6f2
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94
diff
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|
6925 HeapWord* addr = (HeapWord*)obj; |
|
ba764ed4b6f2
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94
diff
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|
6926 if (_span.contains(addr)) { |
|
ba764ed4b6f2
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94
diff
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|
6927 // this should be made more efficient |
|
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
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94
diff
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|
6928 _bitMap->mark(addr); |
|
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
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94
diff
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|
6929 } |
|
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94
diff
changeset
|
6930 } |
|
ba764ed4b6f2
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diff
changeset
|
6931 |
|
ba764ed4b6f2
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94
diff
changeset
|
6932 void MarkRefsIntoClosure::do_oop(oop* p) { MarkRefsIntoClosure::do_oop_work(p); } |
|
ba764ed4b6f2
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94
diff
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|
6933 void MarkRefsIntoClosure::do_oop(narrowOop* p) { MarkRefsIntoClosure::do_oop_work(p); } |
| 0 | 6934 |
| 11975 | 6935 Par_MarkRefsIntoClosure::Par_MarkRefsIntoClosure( |
| 6936 MemRegion span, CMSBitMap* bitMap): | |
| 6937 _span(span), | |
| 6938 _bitMap(bitMap) | |
| 6939 { | |
| 6940 assert(_ref_processor == NULL, "deliberately left NULL"); | |
| 6941 assert(_bitMap->covers(_span), "_bitMap/_span mismatch"); | |
| 6942 } | |
| 6943 | |
| 6944 void Par_MarkRefsIntoClosure::do_oop(oop obj) { | |
| 6945 // if p points into _span, then mark corresponding bit in _markBitMap | |
| 6946 assert(obj->is_oop(), "expected an oop"); | |
| 6947 HeapWord* addr = (HeapWord*)obj; | |
| 6948 if (_span.contains(addr)) { | |
| 6949 // this should be made more efficient | |
| 6950 _bitMap->par_mark(addr); | |
| 6951 } | |
| 6952 } | |
| 6953 | |
| 6954 void Par_MarkRefsIntoClosure::do_oop(oop* p) { Par_MarkRefsIntoClosure::do_oop_work(p); } | |
| 6955 void Par_MarkRefsIntoClosure::do_oop(narrowOop* p) { Par_MarkRefsIntoClosure::do_oop_work(p); } | |
| 6956 | |
| 0 | 6957 // A variant of the above, used for CMS marking verification. |
| 6958 MarkRefsIntoVerifyClosure::MarkRefsIntoVerifyClosure( | |
|
994
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993
diff
changeset
|
6959 MemRegion span, CMSBitMap* verification_bm, CMSBitMap* cms_bm): |
| 0 | 6960 _span(span), |
| 6961 _verification_bm(verification_bm), | |
|
994
753cf9794df9
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jrose
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993
diff
changeset
|
6962 _cms_bm(cms_bm) |
|
753cf9794df9
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jrose
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993
diff
changeset
|
6963 { |
| 0 | 6964 assert(_ref_processor == NULL, "deliberately left NULL"); |
| 6965 assert(_verification_bm->covers(_span), "_verification_bm/_span mismatch"); | |
| 6966 } | |
| 6967 | |
|
113
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diff
changeset
|
6968 void MarkRefsIntoVerifyClosure::do_oop(oop obj) { |
| 0 | 6969 // if p points into _span, then mark corresponding bit in _markBitMap |
|
113
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|
6970 assert(obj->is_oop(), "expected an oop"); |
|
ba764ed4b6f2
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coleenp
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94
diff
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|
6971 HeapWord* addr = (HeapWord*)obj; |
|
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94
diff
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|
6972 if (_span.contains(addr)) { |
|
ba764ed4b6f2
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94
diff
changeset
|
6973 _verification_bm->mark(addr); |
|
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6974 if (!_cms_bm->isMarked(addr)) { |
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6975 oop(addr)->print(); |
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6976 gclog_or_tty->print_cr(" (" INTPTR_FORMAT " should have been marked)", addr); |
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6977 fatal("... aborting"); |
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6978 } |
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6979 } |
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6980 } |
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6981 |
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6982 void MarkRefsIntoVerifyClosure::do_oop(oop* p) { MarkRefsIntoVerifyClosure::do_oop_work(p); } |
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6983 void MarkRefsIntoVerifyClosure::do_oop(narrowOop* p) { MarkRefsIntoVerifyClosure::do_oop_work(p); } |
| 0 | 6984 |
| 6985 ////////////////////////////////////////////////// | |
| 6986 // MarkRefsIntoAndScanClosure | |
| 6987 ////////////////////////////////////////////////// | |
| 6988 | |
| 6989 MarkRefsIntoAndScanClosure::MarkRefsIntoAndScanClosure(MemRegion span, | |
| 6990 ReferenceProcessor* rp, | |
| 6991 CMSBitMap* bit_map, | |
| 6992 CMSBitMap* mod_union_table, | |
| 6993 CMSMarkStack* mark_stack, | |
| 6994 CMSCollector* collector, | |
| 6995 bool should_yield, | |
| 6996 bool concurrent_precleaning): | |
| 6997 _collector(collector), | |
| 6998 _span(span), | |
| 6999 _bit_map(bit_map), | |
| 7000 _mark_stack(mark_stack), | |
| 7001 _pushAndMarkClosure(collector, span, rp, bit_map, mod_union_table, | |
|
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7002 mark_stack, concurrent_precleaning), |
| 0 | 7003 _yield(should_yield), |
| 7004 _concurrent_precleaning(concurrent_precleaning), | |
| 7005 _freelistLock(NULL) | |
| 7006 { | |
| 7007 _ref_processor = rp; | |
| 7008 assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL"); | |
| 7009 } | |
| 7010 | |
| 7011 // This closure is used to mark refs into the CMS generation at the | |
| 7012 // second (final) checkpoint, and to scan and transitively follow | |
| 7013 // the unmarked oops. It is also used during the concurrent precleaning | |
| 7014 // phase while scanning objects on dirty cards in the CMS generation. | |
| 7015 // The marks are made in the marking bit map and the marking stack is | |
| 7016 // used for keeping the (newly) grey objects during the scan. | |
| 7017 // The parallel version (Par_...) appears further below. | |
|
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7018 void MarkRefsIntoAndScanClosure::do_oop(oop obj) { |
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7019 if (obj != NULL) { |
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7020 assert(obj->is_oop(), "expected an oop"); |
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7021 HeapWord* addr = (HeapWord*)obj; |
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7022 assert(_mark_stack->isEmpty(), "pre-condition (eager drainage)"); |
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7023 assert(_collector->overflow_list_is_empty(), |
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7024 "overflow list should be empty"); |
| 0 | 7025 if (_span.contains(addr) && |
| 7026 !_bit_map->isMarked(addr)) { | |
| 7027 // mark bit map (object is now grey) | |
| 7028 _bit_map->mark(addr); | |
| 7029 // push on marking stack (stack should be empty), and drain the | |
| 7030 // stack by applying this closure to the oops in the oops popped | |
| 7031 // from the stack (i.e. blacken the grey objects) | |
|
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7032 bool res = _mark_stack->push(obj); |
| 0 | 7033 assert(res, "Should have space to push on empty stack"); |
| 7034 do { | |
| 7035 oop new_oop = _mark_stack->pop(); | |
| 7036 assert(new_oop != NULL && new_oop->is_oop(), "Expected an oop"); | |
| 7037 assert(_bit_map->isMarked((HeapWord*)new_oop), | |
| 7038 "only grey objects on this stack"); | |
| 7039 // iterate over the oops in this oop, marking and pushing | |
| 7040 // the ones in CMS heap (i.e. in _span). | |
| 7041 new_oop->oop_iterate(&_pushAndMarkClosure); | |
| 7042 // check if it's time to yield | |
| 7043 do_yield_check(); | |
| 7044 } while (!_mark_stack->isEmpty() || | |
| 7045 (!_concurrent_precleaning && take_from_overflow_list())); | |
| 7046 // if marking stack is empty, and we are not doing this | |
| 7047 // during precleaning, then check the overflow list | |
| 7048 } | |
| 7049 assert(_mark_stack->isEmpty(), "post-condition (eager drainage)"); | |
| 7050 assert(_collector->overflow_list_is_empty(), | |
| 7051 "overflow list was drained above"); | |
| 7052 // We could restore evacuated mark words, if any, used for | |
| 7053 // overflow list links here because the overflow list is | |
| 7054 // provably empty here. That would reduce the maximum | |
| 7055 // size requirements for preserved_{oop,mark}_stack. | |
| 7056 // But we'll just postpone it until we are all done | |
| 7057 // so we can just stream through. | |
| 7058 if (!_concurrent_precleaning && CMSOverflowEarlyRestoration) { | |
| 7059 _collector->restore_preserved_marks_if_any(); | |
| 7060 assert(_collector->no_preserved_marks(), "No preserved marks"); | |
| 7061 } | |
| 7062 assert(!CMSOverflowEarlyRestoration || _collector->no_preserved_marks(), | |
| 7063 "All preserved marks should have been restored above"); | |
| 7064 } | |
| 7065 } | |
| 7066 | |
|
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7067 void MarkRefsIntoAndScanClosure::do_oop(oop* p) { MarkRefsIntoAndScanClosure::do_oop_work(p); } |
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7068 void MarkRefsIntoAndScanClosure::do_oop(narrowOop* p) { MarkRefsIntoAndScanClosure::do_oop_work(p); } |
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7069 |
| 0 | 7070 void MarkRefsIntoAndScanClosure::do_yield_work() { |
| 7071 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 7072 "CMS thread should hold CMS token"); | |
| 7073 assert_lock_strong(_freelistLock); | |
| 7074 assert_lock_strong(_bit_map->lock()); | |
| 7075 // relinquish the free_list_lock and bitMaplock() | |
| 7076 _bit_map->lock()->unlock(); | |
| 7077 _freelistLock->unlock(); | |
| 7078 ConcurrentMarkSweepThread::desynchronize(true); | |
| 7079 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7080 _collector->stopTimer(); | |
| 7081 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 7082 if (PrintCMSStatistics != 0) { | |
| 7083 _collector->incrementYields(); | |
| 7084 } | |
| 7085 _collector->icms_wait(); | |
| 7086 | |
| 7087 // See the comment in coordinator_yield() | |
|
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7088 for (unsigned i = 0; |
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7089 i < CMSYieldSleepCount && |
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7090 ConcurrentMarkSweepThread::should_yield() && |
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7091 !CMSCollector::foregroundGCIsActive(); |
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7092 ++i) { |
| 0 | 7093 os::sleep(Thread::current(), 1, false); |
| 7094 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7095 } | |
| 7096 | |
| 7097 ConcurrentMarkSweepThread::synchronize(true); | |
| 7098 _freelistLock->lock_without_safepoint_check(); | |
| 7099 _bit_map->lock()->lock_without_safepoint_check(); | |
| 7100 _collector->startTimer(); | |
| 7101 } | |
| 7102 | |
| 7103 /////////////////////////////////////////////////////////// | |
| 7104 // Par_MarkRefsIntoAndScanClosure: a parallel version of | |
| 7105 // MarkRefsIntoAndScanClosure | |
| 7106 /////////////////////////////////////////////////////////// | |
| 7107 Par_MarkRefsIntoAndScanClosure::Par_MarkRefsIntoAndScanClosure( | |
| 7108 CMSCollector* collector, MemRegion span, ReferenceProcessor* rp, | |
|
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7109 CMSBitMap* bit_map, OopTaskQueue* work_queue): |
| 0 | 7110 _span(span), |
| 7111 _bit_map(bit_map), | |
| 7112 _work_queue(work_queue), | |
| 7113 _low_water_mark(MIN2((uint)(work_queue->max_elems()/4), | |
| 7114 (uint)(CMSWorkQueueDrainThreshold * ParallelGCThreads))), | |
|
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7115 _par_pushAndMarkClosure(collector, span, rp, bit_map, work_queue) |
| 0 | 7116 { |
| 7117 _ref_processor = rp; | |
| 7118 assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL"); | |
| 7119 } | |
| 7120 | |
| 7121 // This closure is used to mark refs into the CMS generation at the | |
| 7122 // second (final) checkpoint, and to scan and transitively follow | |
| 7123 // the unmarked oops. The marks are made in the marking bit map and | |
| 7124 // the work_queue is used for keeping the (newly) grey objects during | |
| 7125 // the scan phase whence they are also available for stealing by parallel | |
| 7126 // threads. Since the marking bit map is shared, updates are | |
| 7127 // synchronized (via CAS). | |
|
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7128 void Par_MarkRefsIntoAndScanClosure::do_oop(oop obj) { |
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7129 if (obj != NULL) { |
| 0 | 7130 // Ignore mark word because this could be an already marked oop |
| 7131 // that may be chained at the end of the overflow list. | |
|
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7132 assert(obj->is_oop(true), "expected an oop"); |
|
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7133 HeapWord* addr = (HeapWord*)obj; |
| 0 | 7134 if (_span.contains(addr) && |
| 7135 !_bit_map->isMarked(addr)) { | |
| 7136 // mark bit map (object will become grey): | |
| 7137 // It is possible for several threads to be | |
| 7138 // trying to "claim" this object concurrently; | |
| 7139 // the unique thread that succeeds in marking the | |
| 7140 // object first will do the subsequent push on | |
| 7141 // to the work queue (or overflow list). | |
| 7142 if (_bit_map->par_mark(addr)) { | |
| 7143 // push on work_queue (which may not be empty), and trim the | |
| 7144 // queue to an appropriate length by applying this closure to | |
| 7145 // the oops in the oops popped from the stack (i.e. blacken the | |
| 7146 // grey objects) | |
|
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7147 bool res = _work_queue->push(obj); |
| 0 | 7148 assert(res, "Low water mark should be less than capacity?"); |
| 7149 trim_queue(_low_water_mark); | |
| 7150 } // Else, another thread claimed the object | |
| 7151 } | |
| 7152 } | |
| 7153 } | |
| 7154 | |
|
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7155 void Par_MarkRefsIntoAndScanClosure::do_oop(oop* p) { Par_MarkRefsIntoAndScanClosure::do_oop_work(p); } |
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7156 void Par_MarkRefsIntoAndScanClosure::do_oop(narrowOop* p) { Par_MarkRefsIntoAndScanClosure::do_oop_work(p); } |
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7157 |
| 0 | 7158 // This closure is used to rescan the marked objects on the dirty cards |
| 7159 // in the mod union table and the card table proper. | |
| 7160 size_t ScanMarkedObjectsAgainCarefullyClosure::do_object_careful_m( | |
| 7161 oop p, MemRegion mr) { | |
| 7162 | |
| 7163 size_t size = 0; | |
| 7164 HeapWord* addr = (HeapWord*)p; | |
| 7165 DEBUG_ONLY(_collector->verify_work_stacks_empty();) | |
| 7166 assert(_span.contains(addr), "we are scanning the CMS generation"); | |
| 7167 // check if it's time to yield | |
| 7168 if (do_yield_check()) { | |
| 7169 // We yielded for some foreground stop-world work, | |
| 7170 // and we have been asked to abort this ongoing preclean cycle. | |
| 7171 return 0; | |
| 7172 } | |
| 7173 if (_bitMap->isMarked(addr)) { | |
| 7174 // it's marked; is it potentially uninitialized? | |
| 187 | 7175 if (p->klass_or_null() != NULL) { |
| 0 | 7176 // an initialized object; ignore mark word in verification below |
| 7177 // since we are running concurrent with mutators | |
| 7178 assert(p->is_oop(true), "should be an oop"); | |
| 7179 if (p->is_objArray()) { | |
| 7180 // objArrays are precisely marked; restrict scanning | |
| 7181 // to dirty cards only. | |
| 187 | 7182 size = CompactibleFreeListSpace::adjustObjectSize( |
| 7183 p->oop_iterate(_scanningClosure, mr)); | |
| 0 | 7184 } else { |
| 7185 // A non-array may have been imprecisely marked; we need | |
| 7186 // to scan object in its entirety. | |
| 7187 size = CompactibleFreeListSpace::adjustObjectSize( | |
| 7188 p->oop_iterate(_scanningClosure)); | |
| 7189 } | |
| 9152 | 7190 #ifdef ASSERT |
| 0 | 7191 size_t direct_size = |
| 7192 CompactibleFreeListSpace::adjustObjectSize(p->size()); | |
| 7193 assert(size == direct_size, "Inconsistency in size"); | |
| 7194 assert(size >= 3, "Necessary for Printezis marks to work"); | |
| 7195 if (!_bitMap->isMarked(addr+1)) { | |
| 7196 _bitMap->verifyNoOneBitsInRange(addr+2, addr+size); | |
| 7197 } else { | |
| 7198 _bitMap->verifyNoOneBitsInRange(addr+2, addr+size-1); | |
| 7199 assert(_bitMap->isMarked(addr+size-1), | |
| 7200 "inconsistent Printezis mark"); | |
| 7201 } | |
| 9152 | 7202 #endif // ASSERT |
| 0 | 7203 } else { |
| 7204 // an unitialized object | |
| 7205 assert(_bitMap->isMarked(addr+1), "missing Printezis mark?"); | |
| 7206 HeapWord* nextOneAddr = _bitMap->getNextMarkedWordAddress(addr + 2); | |
| 7207 size = pointer_delta(nextOneAddr + 1, addr); | |
| 7208 assert(size == CompactibleFreeListSpace::adjustObjectSize(size), | |
| 7209 "alignment problem"); | |
| 7210 // Note that pre-cleaning needn't redirty the card. OopDesc::set_klass() | |
| 7211 // will dirty the card when the klass pointer is installed in the | |
| 7212 // object (signalling the completion of initialization). | |
| 7213 } | |
| 7214 } else { | |
| 7215 // Either a not yet marked object or an uninitialized object | |
|
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7216 if (p->klass_or_null() == NULL) { |
| 0 | 7217 // An uninitialized object, skip to the next card, since |
| 7218 // we may not be able to read its P-bits yet. | |
| 7219 assert(size == 0, "Initial value"); | |
| 7220 } else { | |
| 7221 // An object not (yet) reached by marking: we merely need to | |
| 7222 // compute its size so as to go look at the next block. | |
| 7223 assert(p->is_oop(true), "should be an oop"); | |
| 7224 size = CompactibleFreeListSpace::adjustObjectSize(p->size()); | |
| 7225 } | |
| 7226 } | |
| 7227 DEBUG_ONLY(_collector->verify_work_stacks_empty();) | |
| 7228 return size; | |
| 7229 } | |
| 7230 | |
| 7231 void ScanMarkedObjectsAgainCarefullyClosure::do_yield_work() { | |
| 7232 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 7233 "CMS thread should hold CMS token"); | |
| 7234 assert_lock_strong(_freelistLock); | |
| 7235 assert_lock_strong(_bitMap->lock()); | |
| 7236 // relinquish the free_list_lock and bitMaplock() | |
| 7237 _bitMap->lock()->unlock(); | |
| 7238 _freelistLock->unlock(); | |
| 7239 ConcurrentMarkSweepThread::desynchronize(true); | |
| 7240 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7241 _collector->stopTimer(); | |
| 7242 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 7243 if (PrintCMSStatistics != 0) { | |
| 7244 _collector->incrementYields(); | |
| 7245 } | |
| 7246 _collector->icms_wait(); | |
| 7247 | |
| 7248 // See the comment in coordinator_yield() | |
| 7249 for (unsigned i = 0; i < CMSYieldSleepCount && | |
|
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7250 ConcurrentMarkSweepThread::should_yield() && |
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7251 !CMSCollector::foregroundGCIsActive(); ++i) { |
| 0 | 7252 os::sleep(Thread::current(), 1, false); |
| 7253 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7254 } | |
| 7255 | |
| 7256 ConcurrentMarkSweepThread::synchronize(true); | |
| 7257 _freelistLock->lock_without_safepoint_check(); | |
| 7258 _bitMap->lock()->lock_without_safepoint_check(); | |
| 7259 _collector->startTimer(); | |
| 7260 } | |
| 7261 | |
| 7262 | |
| 7263 ////////////////////////////////////////////////////////////////// | |
| 7264 // SurvivorSpacePrecleanClosure | |
| 7265 ////////////////////////////////////////////////////////////////// | |
| 7266 // This (single-threaded) closure is used to preclean the oops in | |
| 7267 // the survivor spaces. | |
| 7268 size_t SurvivorSpacePrecleanClosure::do_object_careful(oop p) { | |
| 7269 | |
| 7270 HeapWord* addr = (HeapWord*)p; | |
| 7271 DEBUG_ONLY(_collector->verify_work_stacks_empty();) | |
| 7272 assert(!_span.contains(addr), "we are scanning the survivor spaces"); | |
| 187 | 7273 assert(p->klass_or_null() != NULL, "object should be initializd"); |
| 0 | 7274 // an initialized object; ignore mark word in verification below |
| 7275 // since we are running concurrent with mutators | |
| 7276 assert(p->is_oop(true), "should be an oop"); | |
| 7277 // Note that we do not yield while we iterate over | |
| 7278 // the interior oops of p, pushing the relevant ones | |
| 7279 // on our marking stack. | |
| 7280 size_t size = p->oop_iterate(_scanning_closure); | |
| 7281 do_yield_check(); | |
| 7282 // Observe that below, we do not abandon the preclean | |
| 7283 // phase as soon as we should; rather we empty the | |
| 7284 // marking stack before returning. This is to satisfy | |
| 7285 // some existing assertions. In general, it may be a | |
| 7286 // good idea to abort immediately and complete the marking | |
| 7287 // from the grey objects at a later time. | |
| 7288 while (!_mark_stack->isEmpty()) { | |
| 7289 oop new_oop = _mark_stack->pop(); | |
| 7290 assert(new_oop != NULL && new_oop->is_oop(), "Expected an oop"); | |
| 7291 assert(_bit_map->isMarked((HeapWord*)new_oop), | |
| 7292 "only grey objects on this stack"); | |
| 7293 // iterate over the oops in this oop, marking and pushing | |
| 7294 // the ones in CMS heap (i.e. in _span). | |
| 7295 new_oop->oop_iterate(_scanning_closure); | |
| 7296 // check if it's time to yield | |
| 7297 do_yield_check(); | |
| 7298 } | |
| 7299 unsigned int after_count = | |
| 7300 GenCollectedHeap::heap()->total_collections(); | |
| 7301 bool abort = (_before_count != after_count) || | |
| 7302 _collector->should_abort_preclean(); | |
| 7303 return abort ? 0 : size; | |
| 7304 } | |
| 7305 | |
| 7306 void SurvivorSpacePrecleanClosure::do_yield_work() { | |
| 7307 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 7308 "CMS thread should hold CMS token"); | |
| 7309 assert_lock_strong(_bit_map->lock()); | |
| 7310 // Relinquish the bit map lock | |
| 7311 _bit_map->lock()->unlock(); | |
| 7312 ConcurrentMarkSweepThread::desynchronize(true); | |
| 7313 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7314 _collector->stopTimer(); | |
| 7315 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 7316 if (PrintCMSStatistics != 0) { | |
| 7317 _collector->incrementYields(); | |
| 7318 } | |
| 7319 _collector->icms_wait(); | |
| 7320 | |
| 7321 // See the comment in coordinator_yield() | |
| 7322 for (unsigned i = 0; i < CMSYieldSleepCount && | |
| 7323 ConcurrentMarkSweepThread::should_yield() && | |
| 7324 !CMSCollector::foregroundGCIsActive(); ++i) { | |
| 7325 os::sleep(Thread::current(), 1, false); | |
| 7326 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7327 } | |
| 7328 | |
| 7329 ConcurrentMarkSweepThread::synchronize(true); | |
| 7330 _bit_map->lock()->lock_without_safepoint_check(); | |
| 7331 _collector->startTimer(); | |
| 7332 } | |
| 7333 | |
| 7334 // This closure is used to rescan the marked objects on the dirty cards | |
| 7335 // in the mod union table and the card table proper. In the parallel | |
| 7336 // case, although the bitMap is shared, we do a single read so the | |
| 7337 // isMarked() query is "safe". | |
| 7338 bool ScanMarkedObjectsAgainClosure::do_object_bm(oop p, MemRegion mr) { | |
| 7339 // Ignore mark word because we are running concurrent with mutators | |
| 7340 assert(p->is_oop_or_null(true), "expected an oop or null"); | |
| 7341 HeapWord* addr = (HeapWord*)p; | |
| 7342 assert(_span.contains(addr), "we are scanning the CMS generation"); | |
| 7343 bool is_obj_array = false; | |
| 9152 | 7344 #ifdef ASSERT |
| 0 | 7345 if (!_parallel) { |
| 7346 assert(_mark_stack->isEmpty(), "pre-condition (eager drainage)"); | |
| 7347 assert(_collector->overflow_list_is_empty(), | |
| 7348 "overflow list should be empty"); | |
| 7349 | |
| 7350 } | |
| 9152 | 7351 #endif // ASSERT |
| 0 | 7352 if (_bit_map->isMarked(addr)) { |
| 7353 // Obj arrays are precisely marked, non-arrays are not; | |
| 7354 // so we scan objArrays precisely and non-arrays in their | |
| 7355 // entirety. | |
| 7356 if (p->is_objArray()) { | |
| 7357 is_obj_array = true; | |
| 7358 if (_parallel) { | |
| 7359 p->oop_iterate(_par_scan_closure, mr); | |
| 7360 } else { | |
| 7361 p->oop_iterate(_scan_closure, mr); | |
| 7362 } | |
| 7363 } else { | |
| 7364 if (_parallel) { | |
| 7365 p->oop_iterate(_par_scan_closure); | |
| 7366 } else { | |
| 7367 p->oop_iterate(_scan_closure); | |
| 7368 } | |
| 7369 } | |
| 7370 } | |
| 9152 | 7371 #ifdef ASSERT |
| 0 | 7372 if (!_parallel) { |
| 7373 assert(_mark_stack->isEmpty(), "post-condition (eager drainage)"); | |
| 7374 assert(_collector->overflow_list_is_empty(), | |
| 7375 "overflow list should be empty"); | |
| 7376 | |
| 7377 } | |
| 9152 | 7378 #endif // ASSERT |
| 0 | 7379 return is_obj_array; |
| 7380 } | |
| 7381 | |
| 7382 MarkFromRootsClosure::MarkFromRootsClosure(CMSCollector* collector, | |
| 7383 MemRegion span, | |
| 7384 CMSBitMap* bitMap, CMSMarkStack* markStack, | |
| 7385 bool should_yield, bool verifying): | |
| 7386 _collector(collector), | |
| 7387 _span(span), | |
| 7388 _bitMap(bitMap), | |
| 7389 _mut(&collector->_modUnionTable), | |
| 7390 _markStack(markStack), | |
| 7391 _yield(should_yield), | |
| 7392 _skipBits(0) | |
| 7393 { | |
| 7394 assert(_markStack->isEmpty(), "stack should be empty"); | |
| 7395 _finger = _bitMap->startWord(); | |
| 7396 _threshold = _finger; | |
| 7397 assert(_collector->_restart_addr == NULL, "Sanity check"); | |
| 7398 assert(_span.contains(_finger), "Out of bounds _finger?"); | |
| 7399 DEBUG_ONLY(_verifying = verifying;) | |
| 7400 } | |
| 7401 | |
| 7402 void MarkFromRootsClosure::reset(HeapWord* addr) { | |
| 7403 assert(_markStack->isEmpty(), "would cause duplicates on stack"); | |
| 7404 assert(_span.contains(addr), "Out of bounds _finger?"); | |
| 7405 _finger = addr; | |
| 7406 _threshold = (HeapWord*)round_to( | |
| 7407 (intptr_t)_finger, CardTableModRefBS::card_size); | |
| 7408 } | |
| 7409 | |
| 7410 // Should revisit to see if this should be restructured for | |
| 7411 // greater efficiency. | |
|
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7412 bool MarkFromRootsClosure::do_bit(size_t offset) { |
| 0 | 7413 if (_skipBits > 0) { |
| 7414 _skipBits--; | |
|
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7415 return true; |
| 0 | 7416 } |
| 7417 // convert offset into a HeapWord* | |
| 7418 HeapWord* addr = _bitMap->startWord() + offset; | |
| 7419 assert(_bitMap->endWord() && addr < _bitMap->endWord(), | |
| 7420 "address out of range"); | |
| 7421 assert(_bitMap->isMarked(addr), "tautology"); | |
| 7422 if (_bitMap->isMarked(addr+1)) { | |
| 7423 // this is an allocated but not yet initialized object | |
| 7424 assert(_skipBits == 0, "tautology"); | |
| 7425 _skipBits = 2; // skip next two marked bits ("Printezis-marks") | |
| 7426 oop p = oop(addr); | |
|
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7427 if (p->klass_or_null() == NULL) { |
| 0 | 7428 DEBUG_ONLY(if (!_verifying) {) |
| 7429 // We re-dirty the cards on which this object lies and increase | |
| 7430 // the _threshold so that we'll come back to scan this object | |
| 7431 // during the preclean or remark phase. (CMSCleanOnEnter) | |
| 7432 if (CMSCleanOnEnter) { | |
| 7433 size_t sz = _collector->block_size_using_printezis_bits(addr); | |
| 7434 HeapWord* end_card_addr = (HeapWord*)round_to( | |
| 7435 (intptr_t)(addr+sz), CardTableModRefBS::card_size); | |
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7436 MemRegion redirty_range = MemRegion(addr, end_card_addr); |
| 0 | 7437 assert(!redirty_range.is_empty(), "Arithmetical tautology"); |
| 7438 // Bump _threshold to end_card_addr; note that | |
| 7439 // _threshold cannot possibly exceed end_card_addr, anyhow. | |
| 7440 // This prevents future clearing of the card as the scan proceeds | |
| 7441 // to the right. | |
| 7442 assert(_threshold <= end_card_addr, | |
| 7443 "Because we are just scanning into this object"); | |
| 7444 if (_threshold < end_card_addr) { | |
| 7445 _threshold = end_card_addr; | |
| 7446 } | |
| 187 | 7447 if (p->klass_or_null() != NULL) { |
| 0 | 7448 // Redirty the range of cards... |
| 7449 _mut->mark_range(redirty_range); | |
| 7450 } // ...else the setting of klass will dirty the card anyway. | |
| 7451 } | |
| 7452 DEBUG_ONLY(}) | |
|
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7453 return true; |
| 0 | 7454 } |
| 7455 } | |
| 7456 scanOopsInOop(addr); | |
|
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7457 return true; |
| 0 | 7458 } |
| 7459 | |
| 7460 // We take a break if we've been at this for a while, | |
| 7461 // so as to avoid monopolizing the locks involved. | |
| 7462 void MarkFromRootsClosure::do_yield_work() { | |
| 7463 // First give up the locks, then yield, then re-lock | |
| 7464 // We should probably use a constructor/destructor idiom to | |
| 7465 // do this unlock/lock or modify the MutexUnlocker class to | |
| 7466 // serve our purpose. XXX | |
| 7467 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 7468 "CMS thread should hold CMS token"); | |
| 7469 assert_lock_strong(_bitMap->lock()); | |
| 7470 _bitMap->lock()->unlock(); | |
| 7471 ConcurrentMarkSweepThread::desynchronize(true); | |
| 7472 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7473 _collector->stopTimer(); | |
| 7474 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 7475 if (PrintCMSStatistics != 0) { | |
| 7476 _collector->incrementYields(); | |
| 7477 } | |
| 7478 _collector->icms_wait(); | |
| 7479 | |
| 7480 // See the comment in coordinator_yield() | |
| 7481 for (unsigned i = 0; i < CMSYieldSleepCount && | |
| 7482 ConcurrentMarkSweepThread::should_yield() && | |
| 7483 !CMSCollector::foregroundGCIsActive(); ++i) { | |
| 7484 os::sleep(Thread::current(), 1, false); | |
| 7485 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7486 } | |
| 7487 | |
| 7488 ConcurrentMarkSweepThread::synchronize(true); | |
| 7489 _bitMap->lock()->lock_without_safepoint_check(); | |
| 7490 _collector->startTimer(); | |
| 7491 } | |
| 7492 | |
| 7493 void MarkFromRootsClosure::scanOopsInOop(HeapWord* ptr) { | |
| 7494 assert(_bitMap->isMarked(ptr), "expected bit to be set"); | |
| 7495 assert(_markStack->isEmpty(), | |
| 7496 "should drain stack to limit stack usage"); | |
| 7497 // convert ptr to an oop preparatory to scanning | |
|
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7498 oop obj = oop(ptr); |
| 0 | 7499 // Ignore mark word in verification below, since we |
| 7500 // may be running concurrent with mutators. | |
|
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7501 assert(obj->is_oop(true), "should be an oop"); |
| 0 | 7502 assert(_finger <= ptr, "_finger runneth ahead"); |
| 7503 // advance the finger to right end of this object | |
|
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7504 _finger = ptr + obj->size(); |
| 0 | 7505 assert(_finger > ptr, "we just incremented it above"); |
| 7506 // On large heaps, it may take us some time to get through | |
| 7507 // the marking phase (especially if running iCMS). During | |
| 7508 // this time it's possible that a lot of mutations have | |
| 7509 // accumulated in the card table and the mod union table -- | |
| 7510 // these mutation records are redundant until we have | |
| 7511 // actually traced into the corresponding card. | |
| 7512 // Here, we check whether advancing the finger would make | |
| 7513 // us cross into a new card, and if so clear corresponding | |
| 7514 // cards in the MUT (preclean them in the card-table in the | |
| 7515 // future). | |
| 7516 | |
| 7517 DEBUG_ONLY(if (!_verifying) {) | |
| 7518 // The clean-on-enter optimization is disabled by default, | |
| 7519 // until we fix 6178663. | |
| 7520 if (CMSCleanOnEnter && (_finger > _threshold)) { | |
| 7521 // [_threshold, _finger) represents the interval | |
| 7522 // of cards to be cleared in MUT (or precleaned in card table). | |
| 7523 // The set of cards to be cleared is all those that overlap | |
| 7524 // with the interval [_threshold, _finger); note that | |
| 7525 // _threshold is always kept card-aligned but _finger isn't | |
| 7526 // always card-aligned. | |
| 7527 HeapWord* old_threshold = _threshold; | |
| 7528 assert(old_threshold == (HeapWord*)round_to( | |
| 7529 (intptr_t)old_threshold, CardTableModRefBS::card_size), | |
| 7530 "_threshold should always be card-aligned"); | |
| 7531 _threshold = (HeapWord*)round_to( | |
| 7532 (intptr_t)_finger, CardTableModRefBS::card_size); | |
| 7533 MemRegion mr(old_threshold, _threshold); | |
| 7534 assert(!mr.is_empty(), "Control point invariant"); | |
| 7535 assert(_span.contains(mr), "Should clear within span"); | |
| 7536 _mut->clear_range(mr); | |
| 7537 } | |
| 7538 DEBUG_ONLY(}) | |
| 7539 // Note: the finger doesn't advance while we drain | |
| 7540 // the stack below. | |
| 7541 PushOrMarkClosure pushOrMarkClosure(_collector, | |
| 7542 _span, _bitMap, _markStack, | |
| 7543 _finger, this); | |
|
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7544 bool res = _markStack->push(obj); |
| 0 | 7545 assert(res, "Empty non-zero size stack should have space for single push"); |
| 7546 while (!_markStack->isEmpty()) { | |
| 7547 oop new_oop = _markStack->pop(); | |
| 7548 // Skip verifying header mark word below because we are | |
| 7549 // running concurrent with mutators. | |
| 7550 assert(new_oop->is_oop(true), "Oops! expected to pop an oop"); | |
| 7551 // now scan this oop's oops | |
| 7552 new_oop->oop_iterate(&pushOrMarkClosure); | |
| 7553 do_yield_check(); | |
| 7554 } | |
| 7555 assert(_markStack->isEmpty(), "tautology, emphasizing post-condition"); | |
| 7556 } | |
| 7557 | |
| 7558 Par_MarkFromRootsClosure::Par_MarkFromRootsClosure(CMSConcMarkingTask* task, | |
| 7559 CMSCollector* collector, MemRegion span, | |
| 7560 CMSBitMap* bit_map, | |
| 7561 OopTaskQueue* work_queue, | |
| 7562 CMSMarkStack* overflow_stack, | |
| 7563 bool should_yield): | |
| 7564 _collector(collector), | |
| 7565 _whole_span(collector->_span), | |
| 7566 _span(span), | |
| 7567 _bit_map(bit_map), | |
| 7568 _mut(&collector->_modUnionTable), | |
| 7569 _work_queue(work_queue), | |
| 7570 _overflow_stack(overflow_stack), | |
| 7571 _yield(should_yield), | |
| 7572 _skip_bits(0), | |
| 7573 _task(task) | |
| 7574 { | |
| 7575 assert(_work_queue->size() == 0, "work_queue should be empty"); | |
| 7576 _finger = span.start(); | |
| 7577 _threshold = _finger; // XXX Defer clear-on-enter optimization for now | |
| 7578 assert(_span.contains(_finger), "Out of bounds _finger?"); | |
| 7579 } | |
| 7580 | |
| 7581 // Should revisit to see if this should be restructured for | |
| 7582 // greater efficiency. | |
|
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7583 bool Par_MarkFromRootsClosure::do_bit(size_t offset) { |
| 0 | 7584 if (_skip_bits > 0) { |
| 7585 _skip_bits--; | |
|
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7586 return true; |
| 0 | 7587 } |
| 7588 // convert offset into a HeapWord* | |
| 7589 HeapWord* addr = _bit_map->startWord() + offset; | |
| 7590 assert(_bit_map->endWord() && addr < _bit_map->endWord(), | |
| 7591 "address out of range"); | |
| 7592 assert(_bit_map->isMarked(addr), "tautology"); | |
| 7593 if (_bit_map->isMarked(addr+1)) { | |
| 7594 // this is an allocated object that might not yet be initialized | |
| 7595 assert(_skip_bits == 0, "tautology"); | |
| 7596 _skip_bits = 2; // skip next two marked bits ("Printezis-marks") | |
| 7597 oop p = oop(addr); | |
|
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7598 if (p->klass_or_null() == NULL) { |
| 0 | 7599 // in the case of Clean-on-Enter optimization, redirty card |
| 7600 // and avoid clearing card by increasing the threshold. | |
|
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7601 return true; |
| 0 | 7602 } |
| 7603 } | |
| 7604 scan_oops_in_oop(addr); | |
|
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7605 return true; |
| 0 | 7606 } |
| 7607 | |
| 7608 void Par_MarkFromRootsClosure::scan_oops_in_oop(HeapWord* ptr) { | |
| 7609 assert(_bit_map->isMarked(ptr), "expected bit to be set"); | |
| 7610 // Should we assert that our work queue is empty or | |
| 7611 // below some drain limit? | |
| 7612 assert(_work_queue->size() == 0, | |
| 7613 "should drain stack to limit stack usage"); | |
| 7614 // convert ptr to an oop preparatory to scanning | |
|
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7615 oop obj = oop(ptr); |
| 0 | 7616 // Ignore mark word in verification below, since we |
| 7617 // may be running concurrent with mutators. | |
|
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7618 assert(obj->is_oop(true), "should be an oop"); |
| 0 | 7619 assert(_finger <= ptr, "_finger runneth ahead"); |
| 7620 // advance the finger to right end of this object | |
|
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7621 _finger = ptr + obj->size(); |
| 0 | 7622 assert(_finger > ptr, "we just incremented it above"); |
| 7623 // On large heaps, it may take us some time to get through | |
| 7624 // the marking phase (especially if running iCMS). During | |
| 7625 // this time it's possible that a lot of mutations have | |
| 7626 // accumulated in the card table and the mod union table -- | |
| 7627 // these mutation records are redundant until we have | |
| 7628 // actually traced into the corresponding card. | |
| 7629 // Here, we check whether advancing the finger would make | |
| 7630 // us cross into a new card, and if so clear corresponding | |
| 7631 // cards in the MUT (preclean them in the card-table in the | |
| 7632 // future). | |
| 7633 | |
| 7634 // The clean-on-enter optimization is disabled by default, | |
| 7635 // until we fix 6178663. | |
| 7636 if (CMSCleanOnEnter && (_finger > _threshold)) { | |
| 7637 // [_threshold, _finger) represents the interval | |
| 7638 // of cards to be cleared in MUT (or precleaned in card table). | |
| 7639 // The set of cards to be cleared is all those that overlap | |
| 7640 // with the interval [_threshold, _finger); note that | |
| 7641 // _threshold is always kept card-aligned but _finger isn't | |
| 7642 // always card-aligned. | |
| 7643 HeapWord* old_threshold = _threshold; | |
| 7644 assert(old_threshold == (HeapWord*)round_to( | |
| 7645 (intptr_t)old_threshold, CardTableModRefBS::card_size), | |
| 7646 "_threshold should always be card-aligned"); | |
| 7647 _threshold = (HeapWord*)round_to( | |
| 7648 (intptr_t)_finger, CardTableModRefBS::card_size); | |
| 7649 MemRegion mr(old_threshold, _threshold); | |
| 7650 assert(!mr.is_empty(), "Control point invariant"); | |
| 7651 assert(_span.contains(mr), "Should clear within span"); // _whole_span ?? | |
| 7652 _mut->clear_range(mr); | |
| 7653 } | |
| 7654 | |
| 7655 // Note: the local finger doesn't advance while we drain | |
| 7656 // the stack below, but the global finger sure can and will. | |
| 7657 HeapWord** gfa = _task->global_finger_addr(); | |
| 7658 Par_PushOrMarkClosure pushOrMarkClosure(_collector, | |
| 7659 _span, _bit_map, | |
| 7660 _work_queue, | |
| 7661 _overflow_stack, | |
| 7662 _finger, | |
| 7663 gfa, this); | |
|
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7664 bool res = _work_queue->push(obj); // overflow could occur here |
| 0 | 7665 assert(res, "Will hold once we use workqueues"); |
| 7666 while (true) { | |
| 7667 oop new_oop; | |
| 7668 if (!_work_queue->pop_local(new_oop)) { | |
| 7669 // We emptied our work_queue; check if there's stuff that can | |
| 7670 // be gotten from the overflow stack. | |
| 7671 if (CMSConcMarkingTask::get_work_from_overflow_stack( | |
| 7672 _overflow_stack, _work_queue)) { | |
| 7673 do_yield_check(); | |
| 7674 continue; | |
| 7675 } else { // done | |
| 7676 break; | |
| 7677 } | |
| 7678 } | |
| 7679 // Skip verifying header mark word below because we are | |
| 7680 // running concurrent with mutators. | |
| 7681 assert(new_oop->is_oop(true), "Oops! expected to pop an oop"); | |
| 7682 // now scan this oop's oops | |
| 7683 new_oop->oop_iterate(&pushOrMarkClosure); | |
| 7684 do_yield_check(); | |
| 7685 } | |
| 7686 assert(_work_queue->size() == 0, "tautology, emphasizing post-condition"); | |
| 7687 } | |
| 7688 | |
| 7689 // Yield in response to a request from VM Thread or | |
| 7690 // from mutators. | |
| 7691 void Par_MarkFromRootsClosure::do_yield_work() { | |
| 7692 assert(_task != NULL, "sanity"); | |
| 7693 _task->yield(); | |
| 7694 } | |
| 7695 | |
| 7696 // A variant of the above used for verifying CMS marking work. | |
| 7697 MarkFromRootsVerifyClosure::MarkFromRootsVerifyClosure(CMSCollector* collector, | |
| 7698 MemRegion span, | |
| 7699 CMSBitMap* verification_bm, CMSBitMap* cms_bm, | |
| 7700 CMSMarkStack* mark_stack): | |
| 7701 _collector(collector), | |
| 7702 _span(span), | |
| 7703 _verification_bm(verification_bm), | |
| 7704 _cms_bm(cms_bm), | |
| 7705 _mark_stack(mark_stack), | |
| 7706 _pam_verify_closure(collector, span, verification_bm, cms_bm, | |
| 7707 mark_stack) | |
| 7708 { | |
| 7709 assert(_mark_stack->isEmpty(), "stack should be empty"); | |
| 7710 _finger = _verification_bm->startWord(); | |
| 7711 assert(_collector->_restart_addr == NULL, "Sanity check"); | |
| 7712 assert(_span.contains(_finger), "Out of bounds _finger?"); | |
| 7713 } | |
| 7714 | |
| 7715 void MarkFromRootsVerifyClosure::reset(HeapWord* addr) { | |
| 7716 assert(_mark_stack->isEmpty(), "would cause duplicates on stack"); | |
| 7717 assert(_span.contains(addr), "Out of bounds _finger?"); | |
| 7718 _finger = addr; | |
| 7719 } | |
| 7720 | |
| 7721 // Should revisit to see if this should be restructured for | |
| 7722 // greater efficiency. | |
|
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7723 bool MarkFromRootsVerifyClosure::do_bit(size_t offset) { |
| 0 | 7724 // convert offset into a HeapWord* |
| 7725 HeapWord* addr = _verification_bm->startWord() + offset; | |
| 7726 assert(_verification_bm->endWord() && addr < _verification_bm->endWord(), | |
| 7727 "address out of range"); | |
| 7728 assert(_verification_bm->isMarked(addr), "tautology"); | |
| 7729 assert(_cms_bm->isMarked(addr), "tautology"); | |
| 7730 | |
| 7731 assert(_mark_stack->isEmpty(), | |
| 7732 "should drain stack to limit stack usage"); | |
| 7733 // convert addr to an oop preparatory to scanning | |
|
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7734 oop obj = oop(addr); |
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7735 assert(obj->is_oop(), "should be an oop"); |
| 0 | 7736 assert(_finger <= addr, "_finger runneth ahead"); |
| 7737 // advance the finger to right end of this object | |
|
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7738 _finger = addr + obj->size(); |
| 0 | 7739 assert(_finger > addr, "we just incremented it above"); |
| 7740 // Note: the finger doesn't advance while we drain | |
| 7741 // the stack below. | |
|
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7742 bool res = _mark_stack->push(obj); |
| 0 | 7743 assert(res, "Empty non-zero size stack should have space for single push"); |
| 7744 while (!_mark_stack->isEmpty()) { | |
| 7745 oop new_oop = _mark_stack->pop(); | |
| 7746 assert(new_oop->is_oop(), "Oops! expected to pop an oop"); | |
| 7747 // now scan this oop's oops | |
| 7748 new_oop->oop_iterate(&_pam_verify_closure); | |
| 7749 } | |
| 7750 assert(_mark_stack->isEmpty(), "tautology, emphasizing post-condition"); | |
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7751 return true; |
| 0 | 7752 } |
| 7753 | |
| 7754 PushAndMarkVerifyClosure::PushAndMarkVerifyClosure( | |
| 7755 CMSCollector* collector, MemRegion span, | |
| 7756 CMSBitMap* verification_bm, CMSBitMap* cms_bm, | |
| 7757 CMSMarkStack* mark_stack): | |
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7758 MetadataAwareOopClosure(collector->ref_processor()), |
| 0 | 7759 _collector(collector), |
| 7760 _span(span), | |
| 7761 _verification_bm(verification_bm), | |
| 7762 _cms_bm(cms_bm), | |
| 7763 _mark_stack(mark_stack) | |
| 7764 { } | |
| 7765 | |
|
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7766 void PushAndMarkVerifyClosure::do_oop(oop* p) { PushAndMarkVerifyClosure::do_oop_work(p); } |
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7767 void PushAndMarkVerifyClosure::do_oop(narrowOop* p) { PushAndMarkVerifyClosure::do_oop_work(p); } |
| 0 | 7768 |
| 7769 // Upon stack overflow, we discard (part of) the stack, | |
| 7770 // remembering the least address amongst those discarded | |
| 7771 // in CMSCollector's _restart_address. | |
| 7772 void PushAndMarkVerifyClosure::handle_stack_overflow(HeapWord* lost) { | |
| 7773 // Remember the least grey address discarded | |
| 7774 HeapWord* ra = (HeapWord*)_mark_stack->least_value(lost); | |
| 7775 _collector->lower_restart_addr(ra); | |
| 7776 _mark_stack->reset(); // discard stack contents | |
| 7777 _mark_stack->expand(); // expand the stack if possible | |
| 7778 } | |
| 7779 | |
|
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7780 void PushAndMarkVerifyClosure::do_oop(oop obj) { |
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7781 assert(obj->is_oop_or_null(), "expected an oop or NULL"); |
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7782 HeapWord* addr = (HeapWord*)obj; |
| 0 | 7783 if (_span.contains(addr) && !_verification_bm->isMarked(addr)) { |
| 7784 // Oop lies in _span and isn't yet grey or black | |
| 7785 _verification_bm->mark(addr); // now grey | |
| 7786 if (!_cms_bm->isMarked(addr)) { | |
| 7787 oop(addr)->print(); | |
|
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7788 gclog_or_tty->print_cr(" (" INTPTR_FORMAT " should have been marked)", |
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7789 addr); |
| 0 | 7790 fatal("... aborting"); |
| 7791 } | |
| 7792 | |
|
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7793 if (!_mark_stack->push(obj)) { // stack overflow |
| 0 | 7794 if (PrintCMSStatistics != 0) { |
| 7795 gclog_or_tty->print_cr("CMS marking stack overflow (benign) at " | |
| 7796 SIZE_FORMAT, _mark_stack->capacity()); | |
| 7797 } | |
| 7798 assert(_mark_stack->isFull(), "Else push should have succeeded"); | |
| 7799 handle_stack_overflow(addr); | |
| 7800 } | |
| 7801 // anything including and to the right of _finger | |
| 7802 // will be scanned as we iterate over the remainder of the | |
| 7803 // bit map | |
| 7804 } | |
| 7805 } | |
| 7806 | |
| 7807 PushOrMarkClosure::PushOrMarkClosure(CMSCollector* collector, | |
| 7808 MemRegion span, | |
| 7809 CMSBitMap* bitMap, CMSMarkStack* markStack, | |
| 7810 HeapWord* finger, MarkFromRootsClosure* parent) : | |
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7811 MetadataAwareOopClosure(collector->ref_processor()), |
|
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7812 _collector(collector), |
| 0 | 7813 _span(span), |
| 7814 _bitMap(bitMap), | |
| 7815 _markStack(markStack), | |
| 7816 _finger(finger), | |
| 935 | 7817 _parent(parent) |
| 0 | 7818 { } |
| 7819 | |
| 7820 Par_PushOrMarkClosure::Par_PushOrMarkClosure(CMSCollector* collector, | |
| 7821 MemRegion span, | |
| 7822 CMSBitMap* bit_map, | |
| 7823 OopTaskQueue* work_queue, | |
| 7824 CMSMarkStack* overflow_stack, | |
| 7825 HeapWord* finger, | |
| 7826 HeapWord** global_finger_addr, | |
| 7827 Par_MarkFromRootsClosure* parent) : | |
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7828 MetadataAwareOopClosure(collector->ref_processor()), |
|
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7829 _collector(collector), |
| 0 | 7830 _whole_span(collector->_span), |
| 7831 _span(span), | |
| 7832 _bit_map(bit_map), | |
| 7833 _work_queue(work_queue), | |
| 7834 _overflow_stack(overflow_stack), | |
| 7835 _finger(finger), | |
| 7836 _global_finger_addr(global_finger_addr), | |
| 935 | 7837 _parent(parent) |
| 0 | 7838 { } |
| 7839 | |
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7840 // Assumes thread-safe access by callers, who are |
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7841 // responsible for mutual exclusion. |
| 0 | 7842 void CMSCollector::lower_restart_addr(HeapWord* low) { |
| 7843 assert(_span.contains(low), "Out of bounds addr"); | |
| 7844 if (_restart_addr == NULL) { | |
| 7845 _restart_addr = low; | |
| 7846 } else { | |
| 7847 _restart_addr = MIN2(_restart_addr, low); | |
| 7848 } | |
| 7849 } | |
| 7850 | |
| 7851 // Upon stack overflow, we discard (part of) the stack, | |
| 7852 // remembering the least address amongst those discarded | |
| 7853 // in CMSCollector's _restart_address. | |
| 7854 void PushOrMarkClosure::handle_stack_overflow(HeapWord* lost) { | |
| 7855 // Remember the least grey address discarded | |
| 7856 HeapWord* ra = (HeapWord*)_markStack->least_value(lost); | |
| 7857 _collector->lower_restart_addr(ra); | |
| 7858 _markStack->reset(); // discard stack contents | |
| 7859 _markStack->expand(); // expand the stack if possible | |
| 7860 } | |
| 7861 | |
| 7862 // Upon stack overflow, we discard (part of) the stack, | |
| 7863 // remembering the least address amongst those discarded | |
| 7864 // in CMSCollector's _restart_address. | |
| 7865 void Par_PushOrMarkClosure::handle_stack_overflow(HeapWord* lost) { | |
| 7866 // We need to do this under a mutex to prevent other | |
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7867 // workers from interfering with the work done below. |
| 0 | 7868 MutexLockerEx ml(_overflow_stack->par_lock(), |
| 7869 Mutex::_no_safepoint_check_flag); | |
| 7870 // Remember the least grey address discarded | |
| 7871 HeapWord* ra = (HeapWord*)_overflow_stack->least_value(lost); | |
| 7872 _collector->lower_restart_addr(ra); | |
| 7873 _overflow_stack->reset(); // discard stack contents | |
| 7874 _overflow_stack->expand(); // expand the stack if possible | |
| 7875 } | |
| 7876 | |
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7877 void PushOrMarkClosure::do_oop(oop obj) { |
| 0 | 7878 // Ignore mark word because we are running concurrent with mutators. |
|
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7879 assert(obj->is_oop_or_null(true), "expected an oop or NULL"); |
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7880 HeapWord* addr = (HeapWord*)obj; |
| 0 | 7881 if (_span.contains(addr) && !_bitMap->isMarked(addr)) { |
| 7882 // Oop lies in _span and isn't yet grey or black | |
| 7883 _bitMap->mark(addr); // now grey | |
| 7884 if (addr < _finger) { | |
| 7885 // the bit map iteration has already either passed, or | |
| 7886 // sampled, this bit in the bit map; we'll need to | |
| 7887 // use the marking stack to scan this oop's oops. | |
| 7888 bool simulate_overflow = false; | |
| 7889 NOT_PRODUCT( | |
| 7890 if (CMSMarkStackOverflowALot && | |
| 7891 _collector->simulate_overflow()) { | |
| 7892 // simulate a stack overflow | |
| 7893 simulate_overflow = true; | |
| 7894 } | |
| 7895 ) | |
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7896 if (simulate_overflow || !_markStack->push(obj)) { // stack overflow |
| 0 | 7897 if (PrintCMSStatistics != 0) { |
| 7898 gclog_or_tty->print_cr("CMS marking stack overflow (benign) at " | |
| 7899 SIZE_FORMAT, _markStack->capacity()); | |
| 7900 } | |
| 7901 assert(simulate_overflow || _markStack->isFull(), "Else push should have succeeded"); | |
| 7902 handle_stack_overflow(addr); | |
| 7903 } | |
| 7904 } | |
| 7905 // anything including and to the right of _finger | |
| 7906 // will be scanned as we iterate over the remainder of the | |
| 7907 // bit map | |
| 7908 do_yield_check(); | |
| 7909 } | |
| 7910 } | |
| 7911 | |
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7912 void PushOrMarkClosure::do_oop(oop* p) { PushOrMarkClosure::do_oop_work(p); } |
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7913 void PushOrMarkClosure::do_oop(narrowOop* p) { PushOrMarkClosure::do_oop_work(p); } |
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7914 |
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7915 void Par_PushOrMarkClosure::do_oop(oop obj) { |
| 0 | 7916 // Ignore mark word because we are running concurrent with mutators. |
|
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7917 assert(obj->is_oop_or_null(true), "expected an oop or NULL"); |
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7918 HeapWord* addr = (HeapWord*)obj; |
| 0 | 7919 if (_whole_span.contains(addr) && !_bit_map->isMarked(addr)) { |
| 7920 // Oop lies in _span and isn't yet grey or black | |
| 7921 // We read the global_finger (volatile read) strictly after marking oop | |
| 7922 bool res = _bit_map->par_mark(addr); // now grey | |
| 7923 volatile HeapWord** gfa = (volatile HeapWord**)_global_finger_addr; | |
| 7924 // Should we push this marked oop on our stack? | |
| 7925 // -- if someone else marked it, nothing to do | |
| 7926 // -- if target oop is above global finger nothing to do | |
| 7927 // -- if target oop is in chunk and above local finger | |
| 7928 // then nothing to do | |
| 7929 // -- else push on work queue | |
| 7930 if ( !res // someone else marked it, they will deal with it | |
| 7931 || (addr >= *gfa) // will be scanned in a later task | |
| 7932 || (_span.contains(addr) && addr >= _finger)) { // later in this chunk | |
| 7933 return; | |
| 7934 } | |
| 7935 // the bit map iteration has already either passed, or | |
| 7936 // sampled, this bit in the bit map; we'll need to | |
| 7937 // use the marking stack to scan this oop's oops. | |
| 7938 bool simulate_overflow = false; | |
| 7939 NOT_PRODUCT( | |
| 7940 if (CMSMarkStackOverflowALot && | |
| 7941 _collector->simulate_overflow()) { | |
| 7942 // simulate a stack overflow | |
| 7943 simulate_overflow = true; | |
| 7944 } | |
| 7945 ) | |
| 7946 if (simulate_overflow || | |
|
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7947 !(_work_queue->push(obj) || _overflow_stack->par_push(obj))) { |
| 0 | 7948 // stack overflow |
| 7949 if (PrintCMSStatistics != 0) { | |
| 7950 gclog_or_tty->print_cr("CMS marking stack overflow (benign) at " | |
| 7951 SIZE_FORMAT, _overflow_stack->capacity()); | |
| 7952 } | |
| 7953 // We cannot assert that the overflow stack is full because | |
| 7954 // it may have been emptied since. | |
| 7955 assert(simulate_overflow || | |
| 7956 _work_queue->size() == _work_queue->max_elems(), | |
| 7957 "Else push should have succeeded"); | |
| 7958 handle_stack_overflow(addr); | |
| 7959 } | |
| 7960 do_yield_check(); | |
| 7961 } | |
| 7962 } | |
| 7963 | |
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7964 void Par_PushOrMarkClosure::do_oop(oop* p) { Par_PushOrMarkClosure::do_oop_work(p); } |
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7965 void Par_PushOrMarkClosure::do_oop(narrowOop* p) { Par_PushOrMarkClosure::do_oop_work(p); } |
| 0 | 7966 |
| 7967 PushAndMarkClosure::PushAndMarkClosure(CMSCollector* collector, | |
| 7968 MemRegion span, | |
| 7969 ReferenceProcessor* rp, | |
| 7970 CMSBitMap* bit_map, | |
| 7971 CMSBitMap* mod_union_table, | |
| 7972 CMSMarkStack* mark_stack, | |
| 7973 bool concurrent_precleaning): | |
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7974 MetadataAwareOopClosure(rp), |
|
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7975 _collector(collector), |
| 0 | 7976 _span(span), |
| 7977 _bit_map(bit_map), | |
| 7978 _mod_union_table(mod_union_table), | |
| 7979 _mark_stack(mark_stack), | |
| 935 | 7980 _concurrent_precleaning(concurrent_precleaning) |
| 0 | 7981 { |
| 7982 assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL"); | |
| 7983 } | |
| 7984 | |
| 7985 // Grey object rescan during pre-cleaning and second checkpoint phases -- | |
| 7986 // the non-parallel version (the parallel version appears further below.) | |
|
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7987 void PushAndMarkClosure::do_oop(oop obj) { |
|
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7988 // Ignore mark word verification. If during concurrent precleaning, |
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7989 // the object monitor may be locked. If during the checkpoint |
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7990 // phases, the object may already have been reached by a different |
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7991 // path and may be at the end of the global overflow list (so |
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7992 // the mark word may be NULL). |
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7993 assert(obj->is_oop_or_null(true /* ignore mark word */), |
| 0 | 7994 "expected an oop or NULL"); |
|
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7995 HeapWord* addr = (HeapWord*)obj; |
| 0 | 7996 // Check if oop points into the CMS generation |
| 7997 // and is not marked | |
| 7998 if (_span.contains(addr) && !_bit_map->isMarked(addr)) { | |
| 7999 // a white object ... | |
| 8000 _bit_map->mark(addr); // ... now grey | |
| 8001 // push on the marking stack (grey set) | |
| 8002 bool simulate_overflow = false; | |
| 8003 NOT_PRODUCT( | |
| 8004 if (CMSMarkStackOverflowALot && | |
| 8005 _collector->simulate_overflow()) { | |
| 8006 // simulate a stack overflow | |
| 8007 simulate_overflow = true; | |
| 8008 } | |
| 8009 ) | |
|
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8010 if (simulate_overflow || !_mark_stack->push(obj)) { |
| 0 | 8011 if (_concurrent_precleaning) { |
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8012 // During precleaning we can just dirty the appropriate card(s) |
| 0 | 8013 // in the mod union table, thus ensuring that the object remains |
|
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8014 // in the grey set and continue. In the case of object arrays |
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8015 // we need to dirty all of the cards that the object spans, |
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8016 // since the rescan of object arrays will be limited to the |
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8017 // dirty cards. |
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8018 // Note that no one can be intefering with us in this action |
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8019 // of dirtying the mod union table, so no locking or atomics |
|
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8020 // are required. |
|
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8021 if (obj->is_objArray()) { |
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8022 size_t sz = obj->size(); |
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8023 HeapWord* end_card_addr = (HeapWord*)round_to( |
|
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8024 (intptr_t)(addr+sz), CardTableModRefBS::card_size); |
|
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8025 MemRegion redirty_range = MemRegion(addr, end_card_addr); |
|
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8026 assert(!redirty_range.is_empty(), "Arithmetical tautology"); |
|
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8027 _mod_union_table->mark_range(redirty_range); |
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8028 } else { |
|
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8029 _mod_union_table->mark(addr); |
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8030 } |
| 0 | 8031 _collector->_ser_pmc_preclean_ovflw++; |
| 8032 } else { | |
| 8033 // During the remark phase, we need to remember this oop | |
| 8034 // in the overflow list. | |
|
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8035 _collector->push_on_overflow_list(obj); |
| 0 | 8036 _collector->_ser_pmc_remark_ovflw++; |
| 8037 } | |
| 8038 } | |
| 8039 } | |
| 8040 } | |
| 8041 | |
| 8042 Par_PushAndMarkClosure::Par_PushAndMarkClosure(CMSCollector* collector, | |
| 8043 MemRegion span, | |
| 8044 ReferenceProcessor* rp, | |
| 8045 CMSBitMap* bit_map, | |
|
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8046 OopTaskQueue* work_queue): |
|
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8047 MetadataAwareOopClosure(rp), |
|
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8048 _collector(collector), |
| 0 | 8049 _span(span), |
| 8050 _bit_map(bit_map), | |
| 935 | 8051 _work_queue(work_queue) |
| 0 | 8052 { |
| 8053 assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL"); | |
| 8054 } | |
| 8055 | |
|
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8056 void PushAndMarkClosure::do_oop(oop* p) { PushAndMarkClosure::do_oop_work(p); } |
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8057 void PushAndMarkClosure::do_oop(narrowOop* p) { PushAndMarkClosure::do_oop_work(p); } |
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8058 |
| 0 | 8059 // Grey object rescan during second checkpoint phase -- |
| 8060 // the parallel version. | |
|
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8061 void Par_PushAndMarkClosure::do_oop(oop obj) { |
| 0 | 8062 // In the assert below, we ignore the mark word because |
| 8063 // this oop may point to an already visited object that is | |
| 8064 // on the overflow stack (in which case the mark word has | |
| 8065 // been hijacked for chaining into the overflow stack -- | |
| 8066 // if this is the last object in the overflow stack then | |
| 8067 // its mark word will be NULL). Because this object may | |
| 8068 // have been subsequently popped off the global overflow | |
| 8069 // stack, and the mark word possibly restored to the prototypical | |
| 8070 // value, by the time we get to examined this failing assert in | |
| 8071 // the debugger, is_oop_or_null(false) may subsequently start | |
| 8072 // to hold. | |
|
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8073 assert(obj->is_oop_or_null(true), |
| 0 | 8074 "expected an oop or NULL"); |
|
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8075 HeapWord* addr = (HeapWord*)obj; |
| 0 | 8076 // Check if oop points into the CMS generation |
| 8077 // and is not marked | |
| 8078 if (_span.contains(addr) && !_bit_map->isMarked(addr)) { | |
| 8079 // a white object ... | |
| 8080 // If we manage to "claim" the object, by being the | |
| 8081 // first thread to mark it, then we push it on our | |
| 8082 // marking stack | |
| 8083 if (_bit_map->par_mark(addr)) { // ... now grey | |
| 8084 // push on work queue (grey set) | |
| 8085 bool simulate_overflow = false; | |
| 8086 NOT_PRODUCT( | |
| 8087 if (CMSMarkStackOverflowALot && | |
| 8088 _collector->par_simulate_overflow()) { | |
| 8089 // simulate a stack overflow | |
| 8090 simulate_overflow = true; | |
| 8091 } | |
| 8092 ) | |
|
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8093 if (simulate_overflow || !_work_queue->push(obj)) { |
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8094 _collector->par_push_on_overflow_list(obj); |
| 0 | 8095 _collector->_par_pmc_remark_ovflw++; // imprecise OK: no need to CAS |
| 8096 } | |
| 8097 } // Else, some other thread got there first | |
| 8098 } | |
| 8099 } | |
| 8100 | |
|
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8101 void Par_PushAndMarkClosure::do_oop(oop* p) { Par_PushAndMarkClosure::do_oop_work(p); } |
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8102 void Par_PushAndMarkClosure::do_oop(narrowOop* p) { Par_PushAndMarkClosure::do_oop_work(p); } |
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8103 |
| 0 | 8104 void CMSPrecleanRefsYieldClosure::do_yield_work() { |
| 8105 Mutex* bml = _collector->bitMapLock(); | |
| 8106 assert_lock_strong(bml); | |
| 8107 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 8108 "CMS thread should hold CMS token"); | |
| 8109 | |
| 8110 bml->unlock(); | |
| 8111 ConcurrentMarkSweepThread::desynchronize(true); | |
| 8112 | |
| 8113 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 8114 | |
| 8115 _collector->stopTimer(); | |
| 8116 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 8117 if (PrintCMSStatistics != 0) { | |
| 8118 _collector->incrementYields(); | |
| 8119 } | |
| 8120 _collector->icms_wait(); | |
| 8121 | |
| 8122 // See the comment in coordinator_yield() | |
| 8123 for (unsigned i = 0; i < CMSYieldSleepCount && | |
| 8124 ConcurrentMarkSweepThread::should_yield() && | |
| 8125 !CMSCollector::foregroundGCIsActive(); ++i) { | |
| 8126 os::sleep(Thread::current(), 1, false); | |
| 8127 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 8128 } | |
| 8129 | |
| 8130 ConcurrentMarkSweepThread::synchronize(true); | |
| 8131 bml->lock(); | |
| 8132 | |
| 8133 _collector->startTimer(); | |
| 8134 } | |
| 8135 | |
| 8136 bool CMSPrecleanRefsYieldClosure::should_return() { | |
| 8137 if (ConcurrentMarkSweepThread::should_yield()) { | |
| 8138 do_yield_work(); | |
| 8139 } | |
| 8140 return _collector->foregroundGCIsActive(); | |
| 8141 } | |
| 8142 | |
| 8143 void MarkFromDirtyCardsClosure::do_MemRegion(MemRegion mr) { | |
| 8144 assert(((size_t)mr.start())%CardTableModRefBS::card_size_in_words == 0, | |
| 8145 "mr should be aligned to start at a card boundary"); | |
| 8146 // We'd like to assert: | |
| 8147 // assert(mr.word_size()%CardTableModRefBS::card_size_in_words == 0, | |
| 8148 // "mr should be a range of cards"); | |
| 8149 // However, that would be too strong in one case -- the last | |
| 8150 // partition ends at _unallocated_block which, in general, can be | |
| 8151 // an arbitrary boundary, not necessarily card aligned. | |
| 8152 if (PrintCMSStatistics != 0) { | |
| 8153 _num_dirty_cards += | |
| 8154 mr.word_size()/CardTableModRefBS::card_size_in_words; | |
| 8155 } | |
| 8156 _space->object_iterate_mem(mr, &_scan_cl); | |
| 8157 } | |
| 8158 | |
| 8159 SweepClosure::SweepClosure(CMSCollector* collector, | |
| 8160 ConcurrentMarkSweepGeneration* g, | |
| 8161 CMSBitMap* bitMap, bool should_yield) : | |
| 8162 _collector(collector), | |
| 8163 _g(g), | |
| 8164 _sp(g->cmsSpace()), | |
| 8165 _limit(_sp->sweep_limit()), | |
| 8166 _freelistLock(_sp->freelistLock()), | |
| 8167 _bitMap(bitMap), | |
| 8168 _yield(should_yield), | |
| 8169 _inFreeRange(false), // No free range at beginning of sweep | |
| 8170 _freeRangeInFreeLists(false), // No free range at beginning of sweep | |
| 8171 _lastFreeRangeCoalesced(false), | |
| 8172 _freeFinger(g->used_region().start()) | |
| 8173 { | |
| 8174 NOT_PRODUCT( | |
| 8175 _numObjectsFreed = 0; | |
| 8176 _numWordsFreed = 0; | |
| 8177 _numObjectsLive = 0; | |
| 8178 _numWordsLive = 0; | |
| 8179 _numObjectsAlreadyFree = 0; | |
| 8180 _numWordsAlreadyFree = 0; | |
| 8181 _last_fc = NULL; | |
| 8182 | |
| 8183 _sp->initializeIndexedFreeListArrayReturnedBytes(); | |
|
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8184 _sp->dictionary()->initialize_dict_returned_bytes(); |
| 0 | 8185 ) |
| 8186 assert(_limit >= _sp->bottom() && _limit <= _sp->end(), | |
| 8187 "sweep _limit out of bounds"); | |
| 8188 if (CMSTraceSweeper) { | |
|
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|
8189 gclog_or_tty->print_cr("\n====================\nStarting new sweep with limit " PTR_FORMAT, |
|
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|
8190 _limit); |
|
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|
8191 } |
|
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|
8192 } |
|
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|
8193 |
|
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|
8194 void SweepClosure::print_on(outputStream* st) const { |
|
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|
8195 tty->print_cr("_sp = [" PTR_FORMAT "," PTR_FORMAT ")", |
|
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|
8196 _sp->bottom(), _sp->end()); |
|
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|
8197 tty->print_cr("_limit = " PTR_FORMAT, _limit); |
|
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|
8198 tty->print_cr("_freeFinger = " PTR_FORMAT, _freeFinger); |
|
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|
8199 NOT_PRODUCT(tty->print_cr("_last_fc = " PTR_FORMAT, _last_fc);) |
|
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|
8200 tty->print_cr("_inFreeRange = %d, _freeRangeInFreeLists = %d, _lastFreeRangeCoalesced = %d", |
|
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|
8201 _inFreeRange, _freeRangeInFreeLists, _lastFreeRangeCoalesced); |
|
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|
8202 } |
|
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|
8203 |
|
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|
8204 #ifndef PRODUCT |
|
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|
8205 // Assertion checking only: no useful work in product mode -- |
|
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|
8206 // however, if any of the flags below become product flags, |
|
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|
8207 // you may need to review this code to see if it needs to be |
|
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|
8208 // enabled in product mode. |
| 0 | 8209 SweepClosure::~SweepClosure() { |
| 8210 assert_lock_strong(_freelistLock); | |
|
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|
8211 assert(_limit >= _sp->bottom() && _limit <= _sp->end(), |
|
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|
8212 "sweep _limit out of bounds"); |
| 0 | 8213 if (inFreeRange()) { |
|
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|
8214 warning("inFreeRange() should have been reset; dumping state of SweepClosure"); |
|
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|
8215 print(); |
|
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|
8216 ShouldNotReachHere(); |
|
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|
8217 } |
|
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|
8218 if (Verbose && PrintGC) { |
|
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|
8219 gclog_or_tty->print("Collected "SIZE_FORMAT" objects, " SIZE_FORMAT " bytes", |
|
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|
8220 _numObjectsFreed, _numWordsFreed*sizeof(HeapWord)); |
|
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|
8221 gclog_or_tty->print_cr("\nLive "SIZE_FORMAT" objects, " |
|
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|
8222 SIZE_FORMAT" bytes " |
|
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|
8223 "Already free "SIZE_FORMAT" objects, "SIZE_FORMAT" bytes", |
|
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|
8224 _numObjectsLive, _numWordsLive*sizeof(HeapWord), |
|
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|
8225 _numObjectsAlreadyFree, _numWordsAlreadyFree*sizeof(HeapWord)); |
|
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|
8226 size_t totalBytes = (_numWordsFreed + _numWordsLive + _numWordsAlreadyFree) |
|
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|
8227 * sizeof(HeapWord); |
|
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|
8228 gclog_or_tty->print_cr("Total sweep: "SIZE_FORMAT" bytes", totalBytes); |
|
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|
8229 |
|
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|
8230 if (PrintCMSStatistics && CMSVerifyReturnedBytes) { |
|
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|
8231 size_t indexListReturnedBytes = _sp->sumIndexedFreeListArrayReturnedBytes(); |
|
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8232 size_t dict_returned_bytes = _sp->dictionary()->sum_dict_returned_bytes(); |
|
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8233 size_t returned_bytes = indexListReturnedBytes + dict_returned_bytes; |
|
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8234 gclog_or_tty->print("Returned "SIZE_FORMAT" bytes", returned_bytes); |
|
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|
8235 gclog_or_tty->print(" Indexed List Returned "SIZE_FORMAT" bytes", |
|
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|
8236 indexListReturnedBytes); |
|
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|
8237 gclog_or_tty->print_cr(" Dictionary Returned "SIZE_FORMAT" bytes", |
|
6028
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|
8238 dict_returned_bytes); |
|
3746
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|
8239 } |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8240 } |
| 0 | 8241 if (CMSTraceSweeper) { |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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3356
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changeset
|
8242 gclog_or_tty->print_cr("end of sweep with _limit = " PTR_FORMAT "\n================", |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8243 _limit); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8244 } |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8245 } |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8246 #endif // PRODUCT |
| 0 | 8247 |
| 8248 void SweepClosure::initialize_free_range(HeapWord* freeFinger, | |
| 8249 bool freeRangeInFreeLists) { | |
| 8250 if (CMSTraceSweeper) { | |
|
2132
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7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
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|
8251 gclog_or_tty->print("---- Start free range at 0x%x with free block (%d)\n", |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
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changeset
|
8252 freeFinger, freeRangeInFreeLists); |
| 0 | 8253 } |
| 8254 assert(!inFreeRange(), "Trampling existing free range"); | |
| 8255 set_inFreeRange(true); | |
| 8256 set_lastFreeRangeCoalesced(false); | |
| 8257 | |
| 8258 set_freeFinger(freeFinger); | |
| 8259 set_freeRangeInFreeLists(freeRangeInFreeLists); | |
| 8260 if (CMSTestInFreeList) { | |
| 8261 if (freeRangeInFreeLists) { | |
| 8262 FreeChunk* fc = (FreeChunk*) freeFinger; | |
|
6028
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jmasa
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|
8263 assert(fc->is_free(), "A chunk on the free list should be free."); |
| 0 | 8264 assert(fc->size() > 0, "Free range should have a size"); |
|
6028
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jmasa
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|
8265 assert(_sp->verify_chunk_in_free_list(fc), "Chunk is not in free lists"); |
| 0 | 8266 } |
| 8267 } | |
| 8268 } | |
| 8269 | |
| 8270 // Note that the sweeper runs concurrently with mutators. Thus, | |
| 8271 // it is possible for direct allocation in this generation to happen | |
| 8272 // in the middle of the sweep. Note that the sweeper also coalesces | |
| 8273 // contiguous free blocks. Thus, unless the sweeper and the allocator | |
| 8274 // synchronize appropriately freshly allocated blocks may get swept up. | |
| 8275 // This is accomplished by the sweeper locking the free lists while | |
| 8276 // it is sweeping. Thus blocks that are determined to be free are | |
| 8277 // indeed free. There is however one additional complication: | |
| 8278 // blocks that have been allocated since the final checkpoint and | |
| 8279 // mark, will not have been marked and so would be treated as | |
| 8280 // unreachable and swept up. To prevent this, the allocator marks | |
| 8281 // the bit map when allocating during the sweep phase. This leads, | |
| 8282 // however, to a further complication -- objects may have been allocated | |
| 8283 // but not yet initialized -- in the sense that the header isn't yet | |
| 8284 // installed. The sweeper can not then determine the size of the block | |
| 8285 // in order to skip over it. To deal with this case, we use a technique | |
| 8286 // (due to Printezis) to encode such uninitialized block sizes in the | |
| 8287 // bit map. Since the bit map uses a bit per every HeapWord, but the | |
| 8288 // CMS generation has a minimum object size of 3 HeapWords, it follows | |
| 8289 // that "normal marks" won't be adjacent in the bit map (there will | |
| 8290 // always be at least two 0 bits between successive 1 bits). We make use | |
| 8291 // of these "unused" bits to represent uninitialized blocks -- the bit | |
| 8292 // corresponding to the start of the uninitialized object and the next | |
| 8293 // bit are both set. Finally, a 1 bit marks the end of the object that | |
| 8294 // started with the two consecutive 1 bits to indicate its potentially | |
| 8295 // uninitialized state. | |
| 8296 | |
| 8297 size_t SweepClosure::do_blk_careful(HeapWord* addr) { | |
| 8298 FreeChunk* fc = (FreeChunk*)addr; | |
| 8299 size_t res; | |
| 8300 | |
|
1720
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
parents:
1716
diff
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|
8301 // Check if we are done sweeping. Below we check "addr >= _limit" rather |
|
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
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1716
diff
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|
8302 // than "addr == _limit" because although _limit was a block boundary when |
|
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
parents:
1716
diff
changeset
|
8303 // we started the sweep, it may no longer be one because heap expansion |
|
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
parents:
1716
diff
changeset
|
8304 // may have caused us to coalesce the block ending at the address _limit |
|
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
parents:
1716
diff
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|
8305 // with a newly expanded chunk (this happens when _limit was set to the |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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changeset
|
8306 // previous _end of the space), so we may have stepped past _limit: |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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|
8307 // see the following Zeno-like trail of CRs 6977970, 7008136, 7042740. |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
changeset
|
8308 if (addr >= _limit) { // we have swept up to or past the limit: finish up |
| 0 | 8309 assert(_limit >= _sp->bottom() && _limit <= _sp->end(), |
| 8310 "sweep _limit out of bounds"); | |
|
1720
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
parents:
1716
diff
changeset
|
8311 assert(addr < _sp->end(), "addr out of bounds"); |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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parents:
3356
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changeset
|
8312 // Flush any free range we might be holding as a single |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
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|
8313 // coalesced chunk to the appropriate free list. |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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parents:
1994
diff
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|
8314 if (inFreeRange()) { |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8315 assert(freeFinger() >= _sp->bottom() && freeFinger() < _limit, |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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|
8316 err_msg("freeFinger() " PTR_FORMAT" is out-of-bounds", freeFinger())); |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
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|
8317 flush_cur_free_chunk(freeFinger(), |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
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|
8318 pointer_delta(addr, freeFinger())); |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
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|
8319 if (CMSTraceSweeper) { |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8320 gclog_or_tty->print("Sweep: last chunk: "); |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8321 gclog_or_tty->print("put_free_blk 0x%x ("SIZE_FORMAT") " |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
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|
8322 "[coalesced:"SIZE_FORMAT"]\n", |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8323 freeFinger(), pointer_delta(addr, freeFinger()), |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8324 lastFreeRangeCoalesced()); |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8325 } |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8326 } |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8327 |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8328 // help the iterator loop finish |
|
1720
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
parents:
1716
diff
changeset
|
8329 return pointer_delta(_sp->end(), addr); |
|
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
parents:
1716
diff
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|
8330 } |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8331 |
|
1720
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
parents:
1716
diff
changeset
|
8332 assert(addr < _limit, "sweep invariant"); |
| 0 | 8333 // check if we should yield |
| 8334 do_yield_check(addr); | |
|
6028
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jmasa
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6026
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|
8335 if (fc->is_free()) { |
| 0 | 8336 // Chunk that is already free |
| 8337 res = fc->size(); | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8338 do_already_free_chunk(fc); |
| 0 | 8339 debug_only(_sp->verifyFreeLists()); |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
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|
8340 // If we flush the chunk at hand in lookahead_and_flush() |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8341 // and it's coalesced with a preceding chunk, then the |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8342 // process of "mangling" the payload of the coalesced block |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
diff
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|
8343 // will cause erasure of the size information from the |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
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|
8344 // (erstwhile) header of all the coalesced blocks but the |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
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|
8345 // first, so the first disjunct in the assert will not hold |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
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|
8346 // in that specific case (in which case the second disjunct |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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|
8347 // will hold). |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
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|
8348 assert(res == fc->size() || ((HeapWord*)fc) + res >= _limit, |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
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|
8349 "Otherwise the size info doesn't change at this step"); |
| 0 | 8350 NOT_PRODUCT( |
| 8351 _numObjectsAlreadyFree++; | |
| 8352 _numWordsAlreadyFree += res; | |
| 8353 ) | |
| 8354 NOT_PRODUCT(_last_fc = fc;) | |
| 8355 } else if (!_bitMap->isMarked(addr)) { | |
| 8356 // Chunk is fresh garbage | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8357 res = do_garbage_chunk(fc); |
| 0 | 8358 debug_only(_sp->verifyFreeLists()); |
| 8359 NOT_PRODUCT( | |
| 8360 _numObjectsFreed++; | |
| 8361 _numWordsFreed += res; | |
| 8362 ) | |
| 8363 } else { | |
| 8364 // Chunk that is alive. | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
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|
8365 res = do_live_chunk(fc); |
| 0 | 8366 debug_only(_sp->verifyFreeLists()); |
| 8367 NOT_PRODUCT( | |
| 8368 _numObjectsLive++; | |
| 8369 _numWordsLive += res; | |
| 8370 ) | |
| 8371 } | |
| 8372 return res; | |
| 8373 } | |
| 8374 | |
| 8375 // For the smart allocation, record following | |
| 8376 // split deaths - a free chunk is removed from its free list because | |
| 8377 // it is being split into two or more chunks. | |
| 8378 // split birth - a free chunk is being added to its free list because | |
| 8379 // a larger free chunk has been split and resulted in this free chunk. | |
| 8380 // coal death - a free chunk is being removed from its free list because | |
| 8381 // it is being coalesced into a large free chunk. | |
| 8382 // coal birth - a free chunk is being added to its free list because | |
| 8383 // it was created when two or more free chunks where coalesced into | |
| 8384 // this free chunk. | |
| 8385 // | |
| 8386 // These statistics are used to determine the desired number of free | |
| 8387 // chunks of a given size. The desired number is chosen to be relative | |
| 8388 // to the end of a CMS sweep. The desired number at the end of a sweep | |
| 8389 // is the | |
| 8390 // count-at-end-of-previous-sweep (an amount that was enough) | |
| 8391 // - count-at-beginning-of-current-sweep (the excess) | |
| 8392 // + split-births (gains in this size during interval) | |
| 8393 // - split-deaths (demands on this size during interval) | |
| 8394 // where the interval is from the end of one sweep to the end of the | |
| 8395 // next. | |
| 8396 // | |
| 8397 // When sweeping the sweeper maintains an accumulated chunk which is | |
| 8398 // the chunk that is made up of chunks that have been coalesced. That | |
| 8399 // will be termed the left-hand chunk. A new chunk of garbage that | |
| 8400 // is being considered for coalescing will be referred to as the | |
| 8401 // right-hand chunk. | |
| 8402 // | |
| 8403 // When making a decision on whether to coalesce a right-hand chunk with | |
| 8404 // the current left-hand chunk, the current count vs. the desired count | |
| 8405 // of the left-hand chunk is considered. Also if the right-hand chunk | |
| 8406 // is near the large chunk at the end of the heap (see | |
| 8407 // ConcurrentMarkSweepGeneration::isNearLargestChunk()), then the | |
| 8408 // left-hand chunk is coalesced. | |
| 8409 // | |
| 8410 // When making a decision about whether to split a chunk, the desired count | |
| 8411 // vs. the current count of the candidate to be split is also considered. | |
| 8412 // If the candidate is underpopulated (currently fewer chunks than desired) | |
| 8413 // a chunk of an overpopulated (currently more chunks than desired) size may | |
| 8414 // be chosen. The "hint" associated with a free list, if non-null, points | |
| 8415 // to a free list which may be overpopulated. | |
| 8416 // | |
| 8417 | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8418 void SweepClosure::do_already_free_chunk(FreeChunk* fc) { |
|
3746
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3356
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|
8419 const size_t size = fc->size(); |
| 0 | 8420 // Chunks that cannot be coalesced are not in the |
| 8421 // free lists. | |
| 8422 if (CMSTestInFreeList && !fc->cantCoalesce()) { | |
|
6028
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diff
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|
8423 assert(_sp->verify_chunk_in_free_list(fc), |
| 0 | 8424 "free chunk should be in free lists"); |
| 8425 } | |
| 8426 // a chunk that is already free, should not have been | |
| 8427 // marked in the bit map | |
|
3746
537a4053b0f9
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ysr
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3356
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|
8428 HeapWord* const addr = (HeapWord*) fc; |
| 0 | 8429 assert(!_bitMap->isMarked(addr), "free chunk should be unmarked"); |
| 8430 // Verify that the bit map has no bits marked between | |
| 8431 // addr and purported end of this block. | |
| 8432 _bitMap->verifyNoOneBitsInRange(addr + 1, addr + size); | |
| 8433 | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
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|
8434 // Some chunks cannot be coalesced under any circumstances. |
| 0 | 8435 // See the definition of cantCoalesce(). |
| 8436 if (!fc->cantCoalesce()) { | |
| 8437 // This chunk can potentially be coalesced. | |
| 8438 if (_sp->adaptive_freelists()) { | |
| 8439 // All the work is done in | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8440 do_post_free_or_garbage_chunk(fc, size); |
| 0 | 8441 } else { // Not adaptive free lists |
| 8442 // this is a free chunk that can potentially be coalesced by the sweeper; | |
| 8443 if (!inFreeRange()) { | |
| 8444 // if the next chunk is a free block that can't be coalesced | |
| 8445 // it doesn't make sense to remove this chunk from the free lists | |
| 8446 FreeChunk* nextChunk = (FreeChunk*)(addr + size); | |
|
2136
c91cc404ca46
7011940: iCMS: SIGSEGV in SweepClosure::do_already_free_chunk(FreeChunk*)+0x360
ysr
parents:
2132
diff
changeset
|
8447 assert((HeapWord*)nextChunk <= _sp->end(), "Chunk size out of bounds?"); |
|
c91cc404ca46
7011940: iCMS: SIGSEGV in SweepClosure::do_already_free_chunk(FreeChunk*)+0x360
ysr
parents:
2132
diff
changeset
|
8448 if ((HeapWord*)nextChunk < _sp->end() && // There is another free chunk to the right ... |
|
6028
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jmasa
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6026
diff
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|
8449 nextChunk->is_free() && // ... which is free... |
|
2136
c91cc404ca46
7011940: iCMS: SIGSEGV in SweepClosure::do_already_free_chunk(FreeChunk*)+0x360
ysr
parents:
2132
diff
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|
8450 nextChunk->cantCoalesce()) { // ... but can't be coalesced |
| 0 | 8451 // nothing to do |
| 8452 } else { | |
| 8453 // Potentially the start of a new free range: | |
| 8454 // Don't eagerly remove it from the free lists. | |
| 8455 // No need to remove it if it will just be put | |
| 8456 // back again. (Also from a pragmatic point of view | |
| 8457 // if it is a free block in a region that is beyond | |
| 8458 // any allocated blocks, an assertion will fail) | |
| 8459 // Remember the start of a free run. | |
| 8460 initialize_free_range(addr, true); | |
| 8461 // end - can coalesce with next chunk | |
| 8462 } | |
| 8463 } else { | |
| 8464 // the midst of a free range, we are coalescing | |
|
3746
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changeset
|
8465 print_free_block_coalesced(fc); |
| 0 | 8466 if (CMSTraceSweeper) { |
| 8467 gclog_or_tty->print(" -- pick up free block 0x%x (%d)\n", fc, size); | |
| 8468 } | |
| 8469 // remove it from the free lists | |
| 8470 _sp->removeFreeChunkFromFreeLists(fc); | |
| 8471 set_lastFreeRangeCoalesced(true); | |
| 8472 // If the chunk is being coalesced and the current free range is | |
| 8473 // in the free lists, remove the current free range so that it | |
| 8474 // will be returned to the free lists in its entirety - all | |
| 8475 // the coalesced pieces included. | |
| 8476 if (freeRangeInFreeLists()) { | |
| 8477 FreeChunk* ffc = (FreeChunk*) freeFinger(); | |
| 8478 assert(ffc->size() == pointer_delta(addr, freeFinger()), | |
| 8479 "Size of free range is inconsistent with chunk size."); | |
| 8480 if (CMSTestInFreeList) { | |
|
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|
8481 assert(_sp->verify_chunk_in_free_list(ffc), |
| 0 | 8482 "free range is not in free lists"); |
| 8483 } | |
| 8484 _sp->removeFreeChunkFromFreeLists(ffc); | |
| 8485 set_freeRangeInFreeLists(false); | |
| 8486 } | |
| 8487 } | |
| 8488 } | |
|
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|
8489 // Note that if the chunk is not coalescable (the else arm |
|
537a4053b0f9
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|
8490 // below), we unconditionally flush, without needing to do |
|
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|
8491 // a "lookahead," as we do below. |
|
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changeset
|
8492 if (inFreeRange()) lookahead_and_flush(fc, size); |
| 0 | 8493 } else { |
| 8494 // Code path common to both original and adaptive free lists. | |
| 8495 | |
| 8496 // cant coalesce with previous block; this should be treated | |
| 8497 // as the end of a free run if any | |
| 8498 if (inFreeRange()) { | |
| 8499 // we kicked some butt; time to pick up the garbage | |
|
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|
8500 assert(freeFinger() < addr, "freeFinger points too high"); |
|
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7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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diff
changeset
|
8501 flush_cur_free_chunk(freeFinger(), pointer_delta(addr, freeFinger())); |
| 0 | 8502 } |
| 8503 // else, nothing to do, just continue | |
| 8504 } | |
| 8505 } | |
| 8506 | |
|
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|
8507 size_t SweepClosure::do_garbage_chunk(FreeChunk* fc) { |
| 0 | 8508 // This is a chunk of garbage. It is not in any free list. |
| 8509 // Add it to a free list or let it possibly be coalesced into | |
| 8510 // a larger chunk. | |
|
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|
8511 HeapWord* const addr = (HeapWord*) fc; |
|
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|
8512 const size_t size = CompactibleFreeListSpace::adjustObjectSize(oop(addr)->size()); |
| 0 | 8513 |
| 8514 if (_sp->adaptive_freelists()) { | |
| 8515 // Verify that the bit map has no bits marked between | |
| 8516 // addr and purported end of just dead object. | |
| 8517 _bitMap->verifyNoOneBitsInRange(addr + 1, addr + size); | |
| 8518 | |
|
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|
8519 do_post_free_or_garbage_chunk(fc, size); |
| 0 | 8520 } else { |
| 8521 if (!inFreeRange()) { | |
| 8522 // start of a new free range | |
| 8523 assert(size > 0, "A free range should have a size"); | |
| 8524 initialize_free_range(addr, false); | |
| 8525 } else { | |
| 8526 // this will be swept up when we hit the end of the | |
| 8527 // free range | |
| 8528 if (CMSTraceSweeper) { | |
| 8529 gclog_or_tty->print(" -- pick up garbage 0x%x (%d) \n", fc, size); | |
| 8530 } | |
| 8531 // If the chunk is being coalesced and the current free range is | |
| 8532 // in the free lists, remove the current free range so that it | |
| 8533 // will be returned to the free lists in its entirety - all | |
| 8534 // the coalesced pieces included. | |
| 8535 if (freeRangeInFreeLists()) { | |
| 8536 FreeChunk* ffc = (FreeChunk*)freeFinger(); | |
| 8537 assert(ffc->size() == pointer_delta(addr, freeFinger()), | |
| 8538 "Size of free range is inconsistent with chunk size."); | |
| 8539 if (CMSTestInFreeList) { | |
|
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|
8540 assert(_sp->verify_chunk_in_free_list(ffc), |
| 0 | 8541 "free range is not in free lists"); |
| 8542 } | |
| 8543 _sp->removeFreeChunkFromFreeLists(ffc); | |
| 8544 set_freeRangeInFreeLists(false); | |
| 8545 } | |
| 8546 set_lastFreeRangeCoalesced(true); | |
| 8547 } | |
| 8548 // this will be swept up when we hit the end of the free range | |
| 8549 | |
| 8550 // Verify that the bit map has no bits marked between | |
| 8551 // addr and purported end of just dead object. | |
| 8552 _bitMap->verifyNoOneBitsInRange(addr + 1, addr + size); | |
| 8553 } | |
|
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|
8554 assert(_limit >= addr + size, |
|
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|
8555 "A freshly garbage chunk can't possibly straddle over _limit"); |
|
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changeset
|
8556 if (inFreeRange()) lookahead_and_flush(fc, size); |
| 0 | 8557 return size; |
| 8558 } | |
| 8559 | |
|
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changeset
|
8560 size_t SweepClosure::do_live_chunk(FreeChunk* fc) { |
| 0 | 8561 HeapWord* addr = (HeapWord*) fc; |
| 8562 // The sweeper has just found a live object. Return any accumulated | |
| 8563 // left hand chunk to the free lists. | |
| 8564 if (inFreeRange()) { | |
|
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diff
changeset
|
8565 assert(freeFinger() < addr, "freeFinger points too high"); |
|
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7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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diff
changeset
|
8566 flush_cur_free_chunk(freeFinger(), pointer_delta(addr, freeFinger())); |
|
4947ee68d19c
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diff
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|
8567 } |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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diff
changeset
|
8568 |
|
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diff
changeset
|
8569 // This object is live: we'd normally expect this to be |
| 0 | 8570 // an oop, and like to assert the following: |
| 8571 // assert(oop(addr)->is_oop(), "live block should be an oop"); | |
| 8572 // However, as we commented above, this may be an object whose | |
| 8573 // header hasn't yet been initialized. | |
| 8574 size_t size; | |
| 8575 assert(_bitMap->isMarked(addr), "Tautology for this control point"); | |
| 8576 if (_bitMap->isMarked(addr + 1)) { | |
| 8577 // Determine the size from the bit map, rather than trying to | |
| 8578 // compute it from the object header. | |
| 8579 HeapWord* nextOneAddr = _bitMap->getNextMarkedWordAddress(addr + 2); | |
| 8580 size = pointer_delta(nextOneAddr + 1, addr); | |
| 8581 assert(size == CompactibleFreeListSpace::adjustObjectSize(size), | |
| 8582 "alignment problem"); | |
| 8583 | |
| 9152 | 8584 #ifdef ASSERT |
|
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coleenp
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6197
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|
8585 if (oop(addr)->klass_or_null() != NULL) { |
| 0 | 8586 // Ignore mark word because we are running concurrent with mutators |
| 8587 assert(oop(addr)->is_oop(true), "live block should be an oop"); | |
| 8588 assert(size == | |
| 8589 CompactibleFreeListSpace::adjustObjectSize(oop(addr)->size()), | |
| 8590 "P-mark and computed size do not agree"); | |
| 8591 } | |
|
2132
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diff
changeset
|
8592 #endif |
| 0 | 8593 |
| 8594 } else { | |
| 8595 // This should be an initialized object that's alive. | |
|
6725
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coleenp
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6197
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changeset
|
8596 assert(oop(addr)->klass_or_null() != NULL, |
| 0 | 8597 "Should be an initialized object"); |
| 8598 // Ignore mark word because we are running concurrent with mutators | |
| 8599 assert(oop(addr)->is_oop(true), "live block should be an oop"); | |
| 8600 // Verify that the bit map has no bits marked between | |
| 8601 // addr and purported end of this block. | |
| 8602 size = CompactibleFreeListSpace::adjustObjectSize(oop(addr)->size()); | |
| 8603 assert(size >= 3, "Necessary for Printezis marks to work"); | |
| 8604 assert(!_bitMap->isMarked(addr+1), "Tautology for this control point"); | |
| 8605 DEBUG_ONLY(_bitMap->verifyNoOneBitsInRange(addr+2, addr+size);) | |
| 8606 } | |
| 8607 return size; | |
| 8608 } | |
| 8609 | |
|
2132
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1994
diff
changeset
|
8610 void SweepClosure::do_post_free_or_garbage_chunk(FreeChunk* fc, |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
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|
8611 size_t chunkSize) { |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
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|
8612 // do_post_free_or_garbage_chunk() should only be called in the case |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
changeset
|
8613 // of the adaptive free list allocator. |
|
6028
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jmasa
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6026
diff
changeset
|
8614 const bool fcInFreeLists = fc->is_free(); |
| 0 | 8615 assert(_sp->adaptive_freelists(), "Should only be used in this case."); |
| 8616 assert((HeapWord*)fc <= _limit, "sweep invariant"); | |
| 8617 if (CMSTestInFreeList && fcInFreeLists) { | |
|
6028
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jmasa
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6026
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|
8618 assert(_sp->verify_chunk_in_free_list(fc), "free chunk is not in free lists"); |
|
2132
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1994
diff
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|
8619 } |
| 0 | 8620 |
| 8621 if (CMSTraceSweeper) { | |
| 8622 gclog_or_tty->print_cr(" -- pick up another chunk at 0x%x (%d)", fc, chunkSize); | |
| 8623 } | |
| 8624 | |
|
3746
537a4053b0f9
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ysr
parents:
3356
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changeset
|
8625 HeapWord* const fc_addr = (HeapWord*) fc; |
| 0 | 8626 |
| 8627 bool coalesce; | |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8628 const size_t left = pointer_delta(fc_addr, freeFinger()); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8629 const size_t right = chunkSize; |
| 0 | 8630 switch (FLSCoalescePolicy) { |
| 8631 // numeric value forms a coalition aggressiveness metric | |
| 8632 case 0: { // never coalesce | |
| 8633 coalesce = false; | |
| 8634 break; | |
| 8635 } | |
| 8636 case 1: { // coalesce if left & right chunks on overpopulated lists | |
| 8637 coalesce = _sp->coalOverPopulated(left) && | |
| 8638 _sp->coalOverPopulated(right); | |
| 8639 break; | |
| 8640 } | |
| 8641 case 2: { // coalesce if left chunk on overpopulated list (default) | |
| 8642 coalesce = _sp->coalOverPopulated(left); | |
| 8643 break; | |
| 8644 } | |
| 8645 case 3: { // coalesce if left OR right chunk on overpopulated list | |
| 8646 coalesce = _sp->coalOverPopulated(left) || | |
| 8647 _sp->coalOverPopulated(right); | |
| 8648 break; | |
| 8649 } | |
| 8650 case 4: { // always coalesce | |
| 8651 coalesce = true; | |
| 8652 break; | |
| 8653 } | |
| 8654 default: | |
| 8655 ShouldNotReachHere(); | |
| 8656 } | |
| 8657 | |
| 8658 // Should the current free range be coalesced? | |
| 8659 // If the chunk is in a free range and either we decided to coalesce above | |
| 8660 // or the chunk is near the large block at the end of the heap | |
| 8661 // (isNearLargestChunk() returns true), then coalesce this chunk. | |
|
3746
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3356
diff
changeset
|
8662 const bool doCoalesce = inFreeRange() |
|
537a4053b0f9
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ysr
parents:
3356
diff
changeset
|
8663 && (coalesce || _g->isNearLargestChunk(fc_addr)); |
| 0 | 8664 if (doCoalesce) { |
| 8665 // Coalesce the current free range on the left with the new | |
| 8666 // chunk on the right. If either is on a free list, | |
| 8667 // it must be removed from the list and stashed in the closure. | |
| 8668 if (freeRangeInFreeLists()) { | |
|
3746
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ysr
parents:
3356
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changeset
|
8669 FreeChunk* const ffc = (FreeChunk*)freeFinger(); |
|
537a4053b0f9
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ysr
parents:
3356
diff
changeset
|
8670 assert(ffc->size() == pointer_delta(fc_addr, freeFinger()), |
| 0 | 8671 "Size of free range is inconsistent with chunk size."); |
| 8672 if (CMSTestInFreeList) { | |
|
6028
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jmasa
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6026
diff
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|
8673 assert(_sp->verify_chunk_in_free_list(ffc), |
| 0 | 8674 "Chunk is not in free lists"); |
| 8675 } | |
| 8676 _sp->coalDeath(ffc->size()); | |
| 8677 _sp->removeFreeChunkFromFreeLists(ffc); | |
| 8678 set_freeRangeInFreeLists(false); | |
| 8679 } | |
| 8680 if (fcInFreeLists) { | |
| 8681 _sp->coalDeath(chunkSize); | |
| 8682 assert(fc->size() == chunkSize, | |
| 8683 "The chunk has the wrong size or is not in the free lists"); | |
| 8684 _sp->removeFreeChunkFromFreeLists(fc); | |
| 8685 } | |
| 8686 set_lastFreeRangeCoalesced(true); | |
|
3746
537a4053b0f9
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ysr
parents:
3356
diff
changeset
|
8687 print_free_block_coalesced(fc); |
| 0 | 8688 } else { // not in a free range and/or should not coalesce |
| 8689 // Return the current free range and start a new one. | |
| 8690 if (inFreeRange()) { | |
| 8691 // In a free range but cannot coalesce with the right hand chunk. | |
| 8692 // Put the current free range into the free lists. | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8693 flush_cur_free_chunk(freeFinger(), |
|
3746
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ysr
parents:
3356
diff
changeset
|
8694 pointer_delta(fc_addr, freeFinger())); |
| 0 | 8695 } |
| 8696 // Set up for new free range. Pass along whether the right hand | |
| 8697 // chunk is in the free lists. | |
| 8698 initialize_free_range((HeapWord*)fc, fcInFreeLists); | |
| 8699 } | |
| 8700 } | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8701 |
|
3746
537a4053b0f9
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ysr
parents:
3356
diff
changeset
|
8702 // Lookahead flush: |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8703 // If we are tracking a free range, and this is the last chunk that |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8704 // we'll look at because its end crosses past _limit, we'll preemptively |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8705 // flush it along with any free range we may be holding on to. Note that |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8706 // this can be the case only for an already free or freshly garbage |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8707 // chunk. If this block is an object, it can never straddle |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8708 // over _limit. The "straddling" occurs when _limit is set at |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8709 // the previous end of the space when this cycle started, and |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8710 // a subsequent heap expansion caused the previously co-terminal |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8711 // free block to be coalesced with the newly expanded portion, |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8712 // thus rendering _limit a non-block-boundary making it dangerous |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8713 // for the sweeper to step over and examine. |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8714 void SweepClosure::lookahead_and_flush(FreeChunk* fc, size_t chunk_size) { |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8715 assert(inFreeRange(), "Should only be called if currently in a free range."); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8716 HeapWord* const eob = ((HeapWord*)fc) + chunk_size; |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8717 assert(_sp->used_region().contains(eob - 1), |
|
12112
1bb10d3170fa
8022817: CMS should not shrink if compaction was not done
jmasa
parents:
12088
diff
changeset
|
8718 err_msg("eob = " PTR_FORMAT " eob-1 = " PTR_FORMAT " _limit = " PTR_FORMAT |
|
1bb10d3170fa
8022817: CMS should not shrink if compaction was not done
jmasa
parents:
12088
diff
changeset
|
8719 " out of bounds wrt _sp = [" PTR_FORMAT "," PTR_FORMAT ")" |
|
3746
537a4053b0f9
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|
8720 " when examining fc = " PTR_FORMAT "(" SIZE_FORMAT ")", |
|
12112
1bb10d3170fa
8022817: CMS should not shrink if compaction was not done
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|
8721 eob, eob-1, _limit, _sp->bottom(), _sp->end(), fc, chunk_size)); |
|
3746
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|
8722 if (eob >= _limit) { |
|
6028
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|
8723 assert(eob == _limit || fc->is_free(), "Only a free chunk should allow us to cross over the limit"); |
|
3746
537a4053b0f9
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|
8724 if (CMSTraceSweeper) { |
|
537a4053b0f9
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|
8725 gclog_or_tty->print_cr("_limit " PTR_FORMAT " reached or crossed by block " |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8726 "[" PTR_FORMAT "," PTR_FORMAT ") in space " |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8727 "[" PTR_FORMAT "," PTR_FORMAT ")", |
|
537a4053b0f9
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|
8728 _limit, fc, eob, _sp->bottom(), _sp->end()); |
|
537a4053b0f9
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|
8729 } |
|
537a4053b0f9
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|
8730 // Return the storage we are tracking back into the free lists. |
|
537a4053b0f9
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|
8731 if (CMSTraceSweeper) { |
|
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|
8732 gclog_or_tty->print_cr("Flushing ... "); |
|
537a4053b0f9
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|
8733 } |
|
537a4053b0f9
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|
8734 assert(freeFinger() < eob, "Error"); |
|
537a4053b0f9
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|
8735 flush_cur_free_chunk( freeFinger(), pointer_delta(eob, freeFinger())); |
|
537a4053b0f9
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|
8736 } |
|
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|
8737 } |
|
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|
8738 |
|
2132
4947ee68d19c
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changeset
|
8739 void SweepClosure::flush_cur_free_chunk(HeapWord* chunk, size_t size) { |
| 0 | 8740 assert(inFreeRange(), "Should only be called if currently in a free range."); |
| 8741 assert(size > 0, | |
| 8742 "A zero sized chunk cannot be added to the free lists."); | |
| 8743 if (!freeRangeInFreeLists()) { | |
|
2132
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diff
changeset
|
8744 if (CMSTestInFreeList) { |
| 0 | 8745 FreeChunk* fc = (FreeChunk*) chunk; |
|
6028
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|
8746 fc->set_size(size); |
|
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|
8747 assert(!_sp->verify_chunk_in_free_list(fc), |
| 0 | 8748 "chunk should not be in free lists yet"); |
| 8749 } | |
| 8750 if (CMSTraceSweeper) { | |
| 8751 gclog_or_tty->print_cr(" -- add free block 0x%x (%d) to free lists", | |
| 8752 chunk, size); | |
| 8753 } | |
| 8754 // A new free range is going to be starting. The current | |
| 8755 // free range has not been added to the free lists yet or | |
| 8756 // was removed so add it back. | |
| 8757 // If the current free range was coalesced, then the death | |
| 8758 // of the free range was recorded. Record a birth now. | |
| 8759 if (lastFreeRangeCoalesced()) { | |
| 8760 _sp->coalBirth(size); | |
| 8761 } | |
| 8762 _sp->addChunkAndRepairOffsetTable(chunk, size, | |
| 8763 lastFreeRangeCoalesced()); | |
|
3746
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|
8764 } else if (CMSTraceSweeper) { |
|
537a4053b0f9
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changeset
|
8765 gclog_or_tty->print_cr("Already in free list: nothing to flush"); |
| 0 | 8766 } |
| 8767 set_inFreeRange(false); | |
| 8768 set_freeRangeInFreeLists(false); | |
| 8769 } | |
| 8770 | |
| 8771 // We take a break if we've been at this for a while, | |
| 8772 // so as to avoid monopolizing the locks involved. | |
| 8773 void SweepClosure::do_yield_work(HeapWord* addr) { | |
| 8774 // Return current free chunk being used for coalescing (if any) | |
| 8775 // to the appropriate freelist. After yielding, the next | |
| 8776 // free block encountered will start a coalescing range of | |
| 8777 // free blocks. If the next free block is adjacent to the | |
| 8778 // chunk just flushed, they will need to wait for the next | |
| 8779 // sweep to be coalesced. | |
| 8780 if (inFreeRange()) { | |
|
2132
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1994
diff
changeset
|
8781 flush_cur_free_chunk(freeFinger(), pointer_delta(addr, freeFinger())); |
| 0 | 8782 } |
| 8783 | |
| 8784 // First give up the locks, then yield, then re-lock. | |
| 8785 // We should probably use a constructor/destructor idiom to | |
| 8786 // do this unlock/lock or modify the MutexUnlocker class to | |
| 8787 // serve our purpose. XXX | |
| 8788 assert_lock_strong(_bitMap->lock()); | |
| 8789 assert_lock_strong(_freelistLock); | |
| 8790 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 8791 "CMS thread should hold CMS token"); | |
| 8792 _bitMap->lock()->unlock(); | |
| 8793 _freelistLock->unlock(); | |
| 8794 ConcurrentMarkSweepThread::desynchronize(true); | |
| 8795 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 8796 _collector->stopTimer(); | |
| 8797 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 8798 if (PrintCMSStatistics != 0) { | |
| 8799 _collector->incrementYields(); | |
| 8800 } | |
| 8801 _collector->icms_wait(); | |
| 8802 | |
| 8803 // See the comment in coordinator_yield() | |
| 8804 for (unsigned i = 0; i < CMSYieldSleepCount && | |
| 8805 ConcurrentMarkSweepThread::should_yield() && | |
| 8806 !CMSCollector::foregroundGCIsActive(); ++i) { | |
| 8807 os::sleep(Thread::current(), 1, false); | |
| 8808 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 8809 } | |
| 8810 | |
| 8811 ConcurrentMarkSweepThread::synchronize(true); | |
| 8812 _freelistLock->lock(); | |
| 8813 _bitMap->lock()->lock_without_safepoint_check(); | |
| 8814 _collector->startTimer(); | |
| 8815 } | |
| 8816 | |
| 8817 #ifndef PRODUCT | |
| 8818 // This is actually very useful in a product build if it can | |
| 8819 // be called from the debugger. Compile it into the product | |
| 8820 // as needed. | |
|
6028
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|
8821 bool debug_verify_chunk_in_free_list(FreeChunk* fc) { |
|
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
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diff
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|
8822 return debug_cms_space->verify_chunk_in_free_list(fc); |
| 0 | 8823 } |
|
3746
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|
8824 #endif |
|
537a4053b0f9
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|
8825 |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
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|
8826 void SweepClosure::print_free_block_coalesced(FreeChunk* fc) const { |
| 0 | 8827 if (CMSTraceSweeper) { |
|
3746
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ysr
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3356
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changeset
|
8828 gclog_or_tty->print_cr("Sweep:coal_free_blk " PTR_FORMAT " (" SIZE_FORMAT ")", |
|
537a4053b0f9
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|
8829 fc, fc->size()); |
|
537a4053b0f9
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|
8830 } |
|
537a4053b0f9
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|
8831 } |
| 0 | 8832 |
| 8833 // CMSIsAliveClosure | |
| 8834 bool CMSIsAliveClosure::do_object_b(oop obj) { | |
| 8835 HeapWord* addr = (HeapWord*)obj; | |
| 8836 return addr != NULL && | |
| 8837 (!_span.contains(addr) || _bit_map->isMarked(addr)); | |
| 8838 } | |
| 8839 | |
|
6725
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|
8840 |
| 935 | 8841 CMSKeepAliveClosure::CMSKeepAliveClosure( CMSCollector* collector, |
| 8842 MemRegion span, | |
| 8843 CMSBitMap* bit_map, CMSMarkStack* mark_stack, | |
|
6725
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6964458: Reimplement class meta-data storage to use native memory
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|
8844 bool cpc): |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
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|
8845 _collector(collector), |
| 935 | 8846 _span(span), |
| 8847 _bit_map(bit_map), | |
| 8848 _mark_stack(mark_stack), | |
| 8849 _concurrent_precleaning(cpc) { | |
| 8850 assert(!_span.is_empty(), "Empty span could spell trouble"); | |
| 8851 } | |
| 8852 | |
| 8853 | |
| 0 | 8854 // CMSKeepAliveClosure: the serial version |
|
113
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|
8855 void CMSKeepAliveClosure::do_oop(oop obj) { |
|
ba764ed4b6f2
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diff
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|
8856 HeapWord* addr = (HeapWord*)obj; |
| 0 | 8857 if (_span.contains(addr) && |
| 8858 !_bit_map->isMarked(addr)) { | |
| 8859 _bit_map->mark(addr); | |
| 8860 bool simulate_overflow = false; | |
| 8861 NOT_PRODUCT( | |
| 8862 if (CMSMarkStackOverflowALot && | |
| 8863 _collector->simulate_overflow()) { | |
| 8864 // simulate a stack overflow | |
| 8865 simulate_overflow = true; | |
| 8866 } | |
| 8867 ) | |
|
113
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|
8868 if (simulate_overflow || !_mark_stack->push(obj)) { |
|
452
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6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
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360
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|
8869 if (_concurrent_precleaning) { |
|
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
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diff
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|
8870 // We dirty the overflown object and let the remark |
|
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
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360
diff
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|
8871 // phase deal with it. |
|
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
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360
diff
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|
8872 assert(_collector->overflow_list_is_empty(), "Error"); |
|
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
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360
diff
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|
8873 // In the case of object arrays, we need to dirty all of |
|
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
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360
diff
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|
8874 // the cards that the object spans. No locking or atomics |
|
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
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360
diff
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|
8875 // are needed since no one else can be mutating the mod union |
|
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
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360
diff
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|
8876 // table. |
|
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
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360
diff
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|
8877 if (obj->is_objArray()) { |
|
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
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diff
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|
8878 size_t sz = obj->size(); |
|
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
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360
diff
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|
8879 HeapWord* end_card_addr = |
|
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
8880 (HeapWord*)round_to((intptr_t)(addr+sz), CardTableModRefBS::card_size); |
|
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
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diff
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|
8881 MemRegion redirty_range = MemRegion(addr, end_card_addr); |
|
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
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diff
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|
8882 assert(!redirty_range.is_empty(), "Arithmetical tautology"); |
|
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
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360
diff
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|
8883 _collector->_modUnionTable.mark_range(redirty_range); |
|
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
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360
diff
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|
8884 } else { |
|
00b023ae2d78
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ysr
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360
diff
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|
8885 _collector->_modUnionTable.mark(addr); |
|
00b023ae2d78
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|
8886 } |
|
00b023ae2d78
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|
8887 _collector->_ser_kac_preclean_ovflw++; |
|
00b023ae2d78
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360
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|
8888 } else { |
|
00b023ae2d78
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ysr
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|
8889 _collector->push_on_overflow_list(obj); |
|
00b023ae2d78
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|
8890 _collector->_ser_kac_ovflw++; |
|
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|
8891 } |
| 0 | 8892 } |
| 8893 } | |
| 8894 } | |
| 8895 | |
|
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|
8896 void CMSKeepAliveClosure::do_oop(oop* p) { CMSKeepAliveClosure::do_oop_work(p); } |
|
ba764ed4b6f2
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|
8897 void CMSKeepAliveClosure::do_oop(narrowOop* p) { CMSKeepAliveClosure::do_oop_work(p); } |
|
ba764ed4b6f2
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94
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|
8898 |
| 0 | 8899 // CMSParKeepAliveClosure: a parallel version of the above. |
| 8900 // The work queues are private to each closure (thread), | |
| 8901 // but (may be) available for stealing by other threads. | |
|
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|
8902 void CMSParKeepAliveClosure::do_oop(oop obj) { |
|
ba764ed4b6f2
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|
8903 HeapWord* addr = (HeapWord*)obj; |
| 0 | 8904 if (_span.contains(addr) && |
| 8905 !_bit_map->isMarked(addr)) { | |
| 8906 // In general, during recursive tracing, several threads | |
| 8907 // may be concurrently getting here; the first one to | |
| 8908 // "tag" it, claims it. | |
| 8909 if (_bit_map->par_mark(addr)) { | |
|
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|
8910 bool res = _work_queue->push(obj); |
| 0 | 8911 assert(res, "Low water mark should be much less than capacity"); |
| 8912 // Do a recursive trim in the hope that this will keep | |
| 8913 // stack usage lower, but leave some oops for potential stealers | |
| 8914 trim_queue(_low_water_mark); | |
| 8915 } // Else, another thread got there first | |
| 8916 } | |
| 8917 } | |
| 8918 | |
|
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|
8919 void CMSParKeepAliveClosure::do_oop(oop* p) { CMSParKeepAliveClosure::do_oop_work(p); } |
|
ba764ed4b6f2
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|
8920 void CMSParKeepAliveClosure::do_oop(narrowOop* p) { CMSParKeepAliveClosure::do_oop_work(p); } |
|
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|
8921 |
| 0 | 8922 void CMSParKeepAliveClosure::trim_queue(uint max) { |
| 8923 while (_work_queue->size() > max) { | |
| 8924 oop new_oop; | |
| 8925 if (_work_queue->pop_local(new_oop)) { | |
| 8926 assert(new_oop != NULL && new_oop->is_oop(), "Expected an oop"); | |
| 8927 assert(_bit_map->isMarked((HeapWord*)new_oop), | |
| 8928 "no white objects on this stack!"); | |
| 8929 assert(_span.contains((HeapWord*)new_oop), "Out of bounds oop"); | |
| 8930 // iterate over the oops in this oop, marking and pushing | |
| 8931 // the ones in CMS heap (i.e. in _span). | |
| 8932 new_oop->oop_iterate(&_mark_and_push); | |
| 8933 } | |
| 8934 } | |
| 8935 } | |
| 8936 | |
| 935 | 8937 CMSInnerParMarkAndPushClosure::CMSInnerParMarkAndPushClosure( |
| 8938 CMSCollector* collector, | |
| 8939 MemRegion span, CMSBitMap* bit_map, | |
| 8940 OopTaskQueue* work_queue): | |
|
6725
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|
8941 _collector(collector), |
| 935 | 8942 _span(span), |
| 8943 _bit_map(bit_map), | |
| 8944 _work_queue(work_queue) { } | |
| 8945 | |
|
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8946 void CMSInnerParMarkAndPushClosure::do_oop(oop obj) { |
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8947 HeapWord* addr = (HeapWord*)obj; |
| 0 | 8948 if (_span.contains(addr) && |
| 8949 !_bit_map->isMarked(addr)) { | |
| 8950 if (_bit_map->par_mark(addr)) { | |
| 8951 bool simulate_overflow = false; | |
| 8952 NOT_PRODUCT( | |
| 8953 if (CMSMarkStackOverflowALot && | |
| 8954 _collector->par_simulate_overflow()) { | |
| 8955 // simulate a stack overflow | |
| 8956 simulate_overflow = true; | |
| 8957 } | |
| 8958 ) | |
|
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8959 if (simulate_overflow || !_work_queue->push(obj)) { |
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8960 _collector->par_push_on_overflow_list(obj); |
| 0 | 8961 _collector->_par_kac_ovflw++; |
| 8962 } | |
| 8963 } // Else another thread got there already | |
| 8964 } | |
| 8965 } | |
| 8966 | |
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8967 void CMSInnerParMarkAndPushClosure::do_oop(oop* p) { CMSInnerParMarkAndPushClosure::do_oop_work(p); } |
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8968 void CMSInnerParMarkAndPushClosure::do_oop(narrowOop* p) { CMSInnerParMarkAndPushClosure::do_oop_work(p); } |
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8969 |
| 0 | 8970 ////////////////////////////////////////////////////////////////// |
| 8971 // CMSExpansionCause ///////////////////////////// | |
| 8972 ////////////////////////////////////////////////////////////////// | |
| 8973 const char* CMSExpansionCause::to_string(CMSExpansionCause::Cause cause) { | |
| 8974 switch (cause) { | |
| 8975 case _no_expansion: | |
| 8976 return "No expansion"; | |
| 8977 case _satisfy_free_ratio: | |
| 8978 return "Free ratio"; | |
| 8979 case _satisfy_promotion: | |
| 8980 return "Satisfy promotion"; | |
| 8981 case _satisfy_allocation: | |
| 8982 return "allocation"; | |
| 8983 case _allocate_par_lab: | |
| 8984 return "Par LAB"; | |
| 8985 case _allocate_par_spooling_space: | |
| 8986 return "Par Spooling Space"; | |
| 8987 case _adaptive_size_policy: | |
| 8988 return "Ergonomics"; | |
| 8989 default: | |
| 8990 return "unknown"; | |
| 8991 } | |
| 8992 } | |
| 8993 | |
| 8994 void CMSDrainMarkingStackClosure::do_void() { | |
| 8995 // the max number to take from overflow list at a time | |
| 8996 const size_t num = _mark_stack->capacity()/4; | |
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8997 assert(!_concurrent_precleaning || _collector->overflow_list_is_empty(), |
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8998 "Overflow list should be NULL during concurrent phases"); |
| 0 | 8999 while (!_mark_stack->isEmpty() || |
| 9000 // if stack is empty, check the overflow list | |
| 9001 _collector->take_from_overflow_list(num, _mark_stack)) { | |
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9002 oop obj = _mark_stack->pop(); |
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9003 HeapWord* addr = (HeapWord*)obj; |
| 0 | 9004 assert(_span.contains(addr), "Should be within span"); |
| 9005 assert(_bit_map->isMarked(addr), "Should be marked"); | |
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9006 assert(obj->is_oop(), "Should be an oop"); |
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9007 obj->oop_iterate(_keep_alive); |
| 0 | 9008 } |
| 9009 } | |
| 9010 | |
| 9011 void CMSParDrainMarkingStackClosure::do_void() { | |
| 9012 // drain queue | |
| 9013 trim_queue(0); | |
| 9014 } | |
| 9015 | |
| 9016 // Trim our work_queue so its length is below max at return | |
| 9017 void CMSParDrainMarkingStackClosure::trim_queue(uint max) { | |
| 9018 while (_work_queue->size() > max) { | |
| 9019 oop new_oop; | |
| 9020 if (_work_queue->pop_local(new_oop)) { | |
| 9021 assert(new_oop->is_oop(), "Expected an oop"); | |
| 9022 assert(_bit_map->isMarked((HeapWord*)new_oop), | |
| 9023 "no white objects on this stack!"); | |
| 9024 assert(_span.contains((HeapWord*)new_oop), "Out of bounds oop"); | |
| 9025 // iterate over the oops in this oop, marking and pushing | |
| 9026 // the ones in CMS heap (i.e. in _span). | |
| 9027 new_oop->oop_iterate(&_mark_and_push); | |
| 9028 } | |
| 9029 } | |
| 9030 } | |
| 9031 | |
| 9032 //////////////////////////////////////////////////////////////////// | |
| 9033 // Support for Marking Stack Overflow list handling and related code | |
| 9034 //////////////////////////////////////////////////////////////////// | |
| 9035 // Much of the following code is similar in shape and spirit to the | |
| 9036 // code used in ParNewGC. We should try and share that code | |
| 9037 // as much as possible in the future. | |
| 9038 | |
| 9039 #ifndef PRODUCT | |
| 9040 // Debugging support for CMSStackOverflowALot | |
| 9041 | |
| 9042 // It's OK to call this multi-threaded; the worst thing | |
| 9043 // that can happen is that we'll get a bunch of closely | |
| 9044 // spaced simulated oveflows, but that's OK, in fact | |
| 9045 // probably good as it would exercise the overflow code | |
| 9046 // under contention. | |
| 9047 bool CMSCollector::simulate_overflow() { | |
| 9048 if (_overflow_counter-- <= 0) { // just being defensive | |
| 9049 _overflow_counter = CMSMarkStackOverflowInterval; | |
| 9050 return true; | |
| 9051 } else { | |
| 9052 return false; | |
| 9053 } | |
| 9054 } | |
| 9055 | |
| 9056 bool CMSCollector::par_simulate_overflow() { | |
| 9057 return simulate_overflow(); | |
| 9058 } | |
| 9059 #endif | |
| 9060 | |
| 9061 // Single-threaded | |
| 9062 bool CMSCollector::take_from_overflow_list(size_t num, CMSMarkStack* stack) { | |
| 9063 assert(stack->isEmpty(), "Expected precondition"); | |
| 9064 assert(stack->capacity() > num, "Shouldn't bite more than can chew"); | |
| 9065 size_t i = num; | |
| 9066 oop cur = _overflow_list; | |
| 9067 const markOop proto = markOopDesc::prototype(); | |
| 534 | 9068 NOT_PRODUCT(ssize_t n = 0;) |
| 0 | 9069 for (oop next; i > 0 && cur != NULL; cur = next, i--) { |
| 9070 next = oop(cur->mark()); | |
| 9071 cur->set_mark(proto); // until proven otherwise | |
| 9072 assert(cur->is_oop(), "Should be an oop"); | |
| 9073 bool res = stack->push(cur); | |
| 9074 assert(res, "Bit off more than can chew?"); | |
| 9075 NOT_PRODUCT(n++;) | |
| 9076 } | |
| 9077 _overflow_list = cur; | |
| 9078 #ifndef PRODUCT | |
| 9079 assert(_num_par_pushes >= n, "Too many pops?"); | |
| 9080 _num_par_pushes -=n; | |
| 9081 #endif | |
| 9082 return !stack->isEmpty(); | |
| 9083 } | |
| 9084 | |
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9085 #define BUSY (cast_to_oop<intptr_t>(0x1aff1aff)) |
| 534 | 9086 // (MT-safe) Get a prefix of at most "num" from the list. |
| 9087 // The overflow list is chained through the mark word of | |
| 9088 // each object in the list. We fetch the entire list, | |
| 9089 // break off a prefix of the right size and return the | |
| 9090 // remainder. If other threads try to take objects from | |
| 9091 // the overflow list at that time, they will wait for | |
| 9092 // some time to see if data becomes available. If (and | |
| 9093 // only if) another thread places one or more object(s) | |
| 9094 // on the global list before we have returned the suffix | |
| 9095 // to the global list, we will walk down our local list | |
| 9096 // to find its end and append the global list to | |
| 9097 // our suffix before returning it. This suffix walk can | |
| 9098 // prove to be expensive (quadratic in the amount of traffic) | |
| 9099 // when there are many objects in the overflow list and | |
| 9100 // there is much producer-consumer contention on the list. | |
| 9101 // *NOTE*: The overflow list manipulation code here and | |
| 9102 // in ParNewGeneration:: are very similar in shape, | |
| 9103 // except that in the ParNew case we use the old (from/eden) | |
| 9104 // copy of the object to thread the list via its klass word. | |
| 9105 // Because of the common code, if you make any changes in | |
| 9106 // the code below, please check the ParNew version to see if | |
| 9107 // similar changes might be needed. | |
| 9108 // CR 6797058 has been filed to consolidate the common code. | |
| 0 | 9109 bool CMSCollector::par_take_from_overflow_list(size_t num, |
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9110 OopTaskQueue* work_q, |
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9111 int no_of_gc_threads) { |
| 534 | 9112 assert(work_q->size() == 0, "First empty local work queue"); |
| 0 | 9113 assert(num < work_q->max_elems(), "Can't bite more than we can chew"); |
| 9114 if (_overflow_list == NULL) { | |
| 9115 return false; | |
| 9116 } | |
| 9117 // Grab the entire list; we'll put back a suffix | |
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9118 oop prefix = cast_to_oop(Atomic::xchg_ptr(BUSY, &_overflow_list)); |
| 534 | 9119 Thread* tid = Thread::current(); |
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9120 // Before "no_of_gc_threads" was introduced CMSOverflowSpinCount was |
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9121 // set to ParallelGCThreads. |
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9122 size_t CMSOverflowSpinCount = (size_t) no_of_gc_threads; // was ParallelGCThreads; |
| 534 | 9123 size_t sleep_time_millis = MAX2((size_t)1, num/100); |
| 9124 // If the list is busy, we spin for a short while, | |
| 9125 // sleeping between attempts to get the list. | |
| 9126 for (size_t spin = 0; prefix == BUSY && spin < CMSOverflowSpinCount; spin++) { | |
| 9127 os::sleep(tid, sleep_time_millis, false); | |
| 9128 if (_overflow_list == NULL) { | |
| 9129 // Nothing left to take | |
| 9130 return false; | |
| 9131 } else if (_overflow_list != BUSY) { | |
| 9132 // Try and grab the prefix | |
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9133 prefix = cast_to_oop(Atomic::xchg_ptr(BUSY, &_overflow_list)); |
| 534 | 9134 } |
| 9135 } | |
| 9136 // If the list was found to be empty, or we spun long | |
| 9137 // enough, we give up and return empty-handed. If we leave | |
| 9138 // the list in the BUSY state below, it must be the case that | |
| 9139 // some other thread holds the overflow list and will set it | |
| 9140 // to a non-BUSY state in the future. | |
| 9141 if (prefix == NULL || prefix == BUSY) { | |
| 9142 // Nothing to take or waited long enough | |
| 9143 if (prefix == NULL) { | |
| 9144 // Write back the NULL in case we overwrote it with BUSY above | |
| 9145 // and it is still the same value. | |
| 9146 (void) Atomic::cmpxchg_ptr(NULL, &_overflow_list, BUSY); | |
| 9147 } | |
| 9148 return false; | |
| 9149 } | |
| 9150 assert(prefix != NULL && prefix != BUSY, "Error"); | |
| 0 | 9151 size_t i = num; |
| 9152 oop cur = prefix; | |
| 534 | 9153 // Walk down the first "num" objects, unless we reach the end. |
| 0 | 9154 for (; i > 1 && cur->mark() != NULL; cur = oop(cur->mark()), i--); |
| 534 | 9155 if (cur->mark() == NULL) { |
| 9156 // We have "num" or fewer elements in the list, so there | |
| 9157 // is nothing to return to the global list. | |
| 9158 // Write back the NULL in lieu of the BUSY we wrote | |
| 9159 // above, if it is still the same value. | |
| 9160 if (_overflow_list == BUSY) { | |
| 9161 (void) Atomic::cmpxchg_ptr(NULL, &_overflow_list, BUSY); | |
| 9162 } | |
| 9163 } else { | |
| 9164 // Chop off the suffix and rerturn it to the global list. | |
| 9165 assert(cur->mark() != BUSY, "Error"); | |
| 0 | 9166 oop suffix_head = cur->mark(); // suffix will be put back on global list |
| 9167 cur->set_mark(NULL); // break off suffix | |
| 534 | 9168 // It's possible that the list is still in the empty(busy) state |
| 9169 // we left it in a short while ago; in that case we may be | |
| 9170 // able to place back the suffix without incurring the cost | |
| 9171 // of a walk down the list. | |
| 0 | 9172 oop observed_overflow_list = _overflow_list; |
| 534 | 9173 oop cur_overflow_list = observed_overflow_list; |
| 9174 bool attached = false; | |
| 9175 while (observed_overflow_list == BUSY || observed_overflow_list == NULL) { | |
| 0 | 9176 observed_overflow_list = |
| 534 | 9177 (oop) Atomic::cmpxchg_ptr(suffix_head, &_overflow_list, cur_overflow_list); |
| 9178 if (cur_overflow_list == observed_overflow_list) { | |
| 9179 attached = true; | |
| 9180 break; | |
| 9181 } else cur_overflow_list = observed_overflow_list; | |
| 9182 } | |
| 9183 if (!attached) { | |
| 9184 // Too bad, someone else sneaked in (at least) an element; we'll need | |
| 9185 // to do a splice. Find tail of suffix so we can prepend suffix to global | |
| 9186 // list. | |
| 9187 for (cur = suffix_head; cur->mark() != NULL; cur = (oop)(cur->mark())); | |
| 9188 oop suffix_tail = cur; | |
| 9189 assert(suffix_tail != NULL && suffix_tail->mark() == NULL, | |
| 9190 "Tautology"); | |
| 9191 observed_overflow_list = _overflow_list; | |
| 9192 do { | |
| 9193 cur_overflow_list = observed_overflow_list; | |
| 9194 if (cur_overflow_list != BUSY) { | |
| 9195 // Do the splice ... | |
| 9196 suffix_tail->set_mark(markOop(cur_overflow_list)); | |
| 9197 } else { // cur_overflow_list == BUSY | |
| 9198 suffix_tail->set_mark(NULL); | |
| 9199 } | |
| 9200 // ... and try to place spliced list back on overflow_list ... | |
| 9201 observed_overflow_list = | |
| 9202 (oop) Atomic::cmpxchg_ptr(suffix_head, &_overflow_list, cur_overflow_list); | |
| 9203 } while (cur_overflow_list != observed_overflow_list); | |
| 9204 // ... until we have succeeded in doing so. | |
| 9205 } | |
| 0 | 9206 } |
| 9207 | |
| 9208 // Push the prefix elements on work_q | |
| 9209 assert(prefix != NULL, "control point invariant"); | |
| 9210 const markOop proto = markOopDesc::prototype(); | |
| 9211 oop next; | |
| 534 | 9212 NOT_PRODUCT(ssize_t n = 0;) |
| 0 | 9213 for (cur = prefix; cur != NULL; cur = next) { |
| 9214 next = oop(cur->mark()); | |
| 9215 cur->set_mark(proto); // until proven otherwise | |
| 9216 assert(cur->is_oop(), "Should be an oop"); | |
| 9217 bool res = work_q->push(cur); | |
| 9218 assert(res, "Bit off more than we can chew?"); | |
| 9219 NOT_PRODUCT(n++;) | |
| 9220 } | |
| 9221 #ifndef PRODUCT | |
| 9222 assert(_num_par_pushes >= n, "Too many pops?"); | |
| 9223 Atomic::add_ptr(-(intptr_t)n, &_num_par_pushes); | |
| 9224 #endif | |
| 9225 return true; | |
| 9226 } | |
| 9227 | |
| 9228 // Single-threaded | |
| 9229 void CMSCollector::push_on_overflow_list(oop p) { | |
| 9230 NOT_PRODUCT(_num_par_pushes++;) | |
| 9231 assert(p->is_oop(), "Not an oop"); | |
| 9232 preserve_mark_if_necessary(p); | |
| 9233 p->set_mark((markOop)_overflow_list); | |
| 9234 _overflow_list = p; | |
| 9235 } | |
| 9236 | |
| 9237 // Multi-threaded; use CAS to prepend to overflow list | |
| 9238 void CMSCollector::par_push_on_overflow_list(oop p) { | |
| 9239 NOT_PRODUCT(Atomic::inc_ptr(&_num_par_pushes);) | |
| 9240 assert(p->is_oop(), "Not an oop"); | |
| 9241 par_preserve_mark_if_necessary(p); | |
| 9242 oop observed_overflow_list = _overflow_list; | |
| 9243 oop cur_overflow_list; | |
| 9244 do { | |
| 9245 cur_overflow_list = observed_overflow_list; | |
| 534 | 9246 if (cur_overflow_list != BUSY) { |
| 9247 p->set_mark(markOop(cur_overflow_list)); | |
| 9248 } else { | |
| 9249 p->set_mark(NULL); | |
| 9250 } | |
| 0 | 9251 observed_overflow_list = |
| 9252 (oop) Atomic::cmpxchg_ptr(p, &_overflow_list, cur_overflow_list); | |
| 9253 } while (cur_overflow_list != observed_overflow_list); | |
| 9254 } | |
| 534 | 9255 #undef BUSY |
| 0 | 9256 |
| 9257 // Single threaded | |
| 9258 // General Note on GrowableArray: pushes may silently fail | |
| 9259 // because we are (temporarily) out of C-heap for expanding | |
| 9260 // the stack. The problem is quite ubiquitous and affects | |
| 9261 // a lot of code in the JVM. The prudent thing for GrowableArray | |
| 9262 // to do (for now) is to exit with an error. However, that may | |
| 9263 // be too draconian in some cases because the caller may be | |
| 534 | 9264 // able to recover without much harm. For such cases, we |
| 0 | 9265 // should probably introduce a "soft_push" method which returns |
| 9266 // an indication of success or failure with the assumption that | |
| 9267 // the caller may be able to recover from a failure; code in | |
| 9268 // the VM can then be changed, incrementally, to deal with such | |
| 9269 // failures where possible, thus, incrementally hardening the VM | |
| 9270 // in such low resource situations. | |
| 9271 void CMSCollector::preserve_mark_work(oop p, markOop m) { | |
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9272 _preserved_oop_stack.push(p); |
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9273 _preserved_mark_stack.push(m); |
| 0 | 9274 assert(m == p->mark(), "Mark word changed"); |
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9275 assert(_preserved_oop_stack.size() == _preserved_mark_stack.size(), |
| 0 | 9276 "bijection"); |
| 9277 } | |
| 9278 | |
| 9279 // Single threaded | |
| 9280 void CMSCollector::preserve_mark_if_necessary(oop p) { | |
| 9281 markOop m = p->mark(); | |
| 9282 if (m->must_be_preserved(p)) { | |
| 9283 preserve_mark_work(p, m); | |
| 9284 } | |
| 9285 } | |
| 9286 | |
| 9287 void CMSCollector::par_preserve_mark_if_necessary(oop p) { | |
| 9288 markOop m = p->mark(); | |
| 9289 if (m->must_be_preserved(p)) { | |
| 9290 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); | |
| 9291 // Even though we read the mark word without holding | |
| 9292 // the lock, we are assured that it will not change | |
| 9293 // because we "own" this oop, so no other thread can | |
| 9294 // be trying to push it on the overflow list; see | |
| 9295 // the assertion in preserve_mark_work() that checks | |
| 9296 // that m == p->mark(). | |
| 9297 preserve_mark_work(p, m); | |
| 9298 } | |
| 9299 } | |
| 9300 | |
| 9301 // We should be able to do this multi-threaded, | |
| 9302 // a chunk of stack being a task (this is | |
| 9303 // correct because each oop only ever appears | |
| 9304 // once in the overflow list. However, it's | |
| 9305 // not very easy to completely overlap this with | |
| 9306 // other operations, so will generally not be done | |
| 9307 // until all work's been completed. Because we | |
| 9308 // expect the preserved oop stack (set) to be small, | |
| 9309 // it's probably fine to do this single-threaded. | |
| 9310 // We can explore cleverer concurrent/overlapped/parallel | |
| 9311 // processing of preserved marks if we feel the | |
| 9312 // need for this in the future. Stack overflow should | |
| 9313 // be so rare in practice and, when it happens, its | |
| 9314 // effect on performance so great that this will | |
| 9315 // likely just be in the noise anyway. | |
| 9316 void CMSCollector::restore_preserved_marks_if_any() { | |
| 9317 assert(SafepointSynchronize::is_at_safepoint(), | |
| 9318 "world should be stopped"); | |
| 9319 assert(Thread::current()->is_ConcurrentGC_thread() || | |
| 9320 Thread::current()->is_VM_thread(), | |
| 9321 "should be single-threaded"); | |
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9322 assert(_preserved_oop_stack.size() == _preserved_mark_stack.size(), |
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9323 "bijection"); |
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9324 |
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9325 while (!_preserved_oop_stack.is_empty()) { |
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changeset
|
9326 oop p = _preserved_oop_stack.pop(); |
| 0 | 9327 assert(p->is_oop(), "Should be an oop"); |
| 9328 assert(_span.contains(p), "oop should be in _span"); | |
| 9329 assert(p->mark() == markOopDesc::prototype(), | |
| 9330 "Set when taken from overflow list"); | |
|
1836
894b1d7c7e01
6423256: GC stacks should use a better data structure
jcoomes
parents:
1833
diff
changeset
|
9331 markOop m = _preserved_mark_stack.pop(); |
| 0 | 9332 p->set_mark(m); |
| 9333 } | |
|
1836
894b1d7c7e01
6423256: GC stacks should use a better data structure
jcoomes
parents:
1833
diff
changeset
|
9334 assert(_preserved_mark_stack.is_empty() && _preserved_oop_stack.is_empty(), |
| 0 | 9335 "stacks were cleared above"); |
| 9336 } | |
| 9337 | |
| 9338 #ifndef PRODUCT | |
| 9339 bool CMSCollector::no_preserved_marks() const { | |
|
1836
894b1d7c7e01
6423256: GC stacks should use a better data structure
jcoomes
parents:
1833
diff
changeset
|
9340 return _preserved_mark_stack.is_empty() && _preserved_oop_stack.is_empty(); |
| 0 | 9341 } |
| 9342 #endif | |
| 9343 | |
| 9344 CMSAdaptiveSizePolicy* ASConcurrentMarkSweepGeneration::cms_size_policy() const | |
| 9345 { | |
| 9346 GenCollectedHeap* gch = (GenCollectedHeap*) GenCollectedHeap::heap(); | |
| 9347 CMSAdaptiveSizePolicy* size_policy = | |
| 9348 (CMSAdaptiveSizePolicy*) gch->gen_policy()->size_policy(); | |
| 9349 assert(size_policy->is_gc_cms_adaptive_size_policy(), | |
| 9350 "Wrong type for size policy"); | |
| 9351 return size_policy; | |
| 9352 } | |
| 9353 | |
| 9354 void ASConcurrentMarkSweepGeneration::resize(size_t cur_promo_size, | |
| 9355 size_t desired_promo_size) { | |
| 9356 if (cur_promo_size < desired_promo_size) { | |
| 9357 size_t expand_bytes = desired_promo_size - cur_promo_size; | |
| 9358 if (PrintAdaptiveSizePolicy && Verbose) { | |
| 9359 gclog_or_tty->print_cr(" ASConcurrentMarkSweepGeneration::resize " | |
| 9360 "Expanding tenured generation by " SIZE_FORMAT " (bytes)", | |
| 9361 expand_bytes); | |
| 9362 } | |
| 9363 expand(expand_bytes, | |
| 9364 MinHeapDeltaBytes, | |
| 9365 CMSExpansionCause::_adaptive_size_policy); | |
| 9366 } else if (desired_promo_size < cur_promo_size) { | |
| 9367 size_t shrink_bytes = cur_promo_size - desired_promo_size; | |
| 9368 if (PrintAdaptiveSizePolicy && Verbose) { | |
| 9369 gclog_or_tty->print_cr(" ASConcurrentMarkSweepGeneration::resize " | |
| 9370 "Shrinking tenured generation by " SIZE_FORMAT " (bytes)", | |
| 9371 shrink_bytes); | |
| 9372 } | |
| 9373 shrink(shrink_bytes); | |
| 9374 } | |
| 9375 } | |
| 9376 | |
| 9377 CMSGCAdaptivePolicyCounters* ASConcurrentMarkSweepGeneration::gc_adaptive_policy_counters() { | |
| 9378 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 9379 CMSGCAdaptivePolicyCounters* counters = | |
| 9380 (CMSGCAdaptivePolicyCounters*) gch->collector_policy()->counters(); | |
| 9381 assert(counters->kind() == GCPolicyCounters::CMSGCAdaptivePolicyCountersKind, | |
| 9382 "Wrong kind of counters"); | |
| 9383 return counters; | |
| 9384 } | |
| 9385 | |
| 9386 | |
| 9387 void ASConcurrentMarkSweepGeneration::update_counters() { | |
| 9388 if (UsePerfData) { | |
| 9389 _space_counters->update_all(); | |
| 9390 _gen_counters->update_all(); | |
| 9391 CMSGCAdaptivePolicyCounters* counters = gc_adaptive_policy_counters(); | |
| 9392 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 9393 CMSGCStats* gc_stats_l = (CMSGCStats*) gc_stats(); | |
| 9394 assert(gc_stats_l->kind() == GCStats::CMSGCStatsKind, | |
| 9395 "Wrong gc statistics type"); | |
| 9396 counters->update_counters(gc_stats_l); | |
| 9397 } | |
| 9398 } | |
| 9399 | |
| 9400 void ASConcurrentMarkSweepGeneration::update_counters(size_t used) { | |
| 9401 if (UsePerfData) { | |
| 9402 _space_counters->update_used(used); | |
| 9403 _space_counters->update_capacity(); | |
| 9404 _gen_counters->update_all(); | |
| 9405 | |
| 9406 CMSGCAdaptivePolicyCounters* counters = gc_adaptive_policy_counters(); | |
| 9407 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 9408 CMSGCStats* gc_stats_l = (CMSGCStats*) gc_stats(); | |
| 9409 assert(gc_stats_l->kind() == GCStats::CMSGCStatsKind, | |
| 9410 "Wrong gc statistics type"); | |
| 9411 counters->update_counters(gc_stats_l); | |
| 9412 } | |
| 9413 } | |
| 9414 | |
| 9415 void ASConcurrentMarkSweepGeneration::shrink_by(size_t desired_bytes) { | |
| 9416 assert_locked_or_safepoint(Heap_lock); | |
| 9417 assert_lock_strong(freelistLock()); | |
| 9418 HeapWord* old_end = _cmsSpace->end(); | |
| 9419 HeapWord* unallocated_start = _cmsSpace->unallocated_block(); | |
| 9420 assert(old_end >= unallocated_start, "Miscalculation of unallocated_start"); | |
| 9421 FreeChunk* chunk_at_end = find_chunk_at_end(); | |
| 9422 if (chunk_at_end == NULL) { | |
| 9423 // No room to shrink | |
| 9424 if (PrintGCDetails && Verbose) { | |
| 9425 gclog_or_tty->print_cr("No room to shrink: old_end " | |
| 9426 PTR_FORMAT " unallocated_start " PTR_FORMAT | |
| 9427 " chunk_at_end " PTR_FORMAT, | |
| 9428 old_end, unallocated_start, chunk_at_end); | |
| 9429 } | |
| 9430 return; | |
| 9431 } else { | |
| 9432 | |
| 9433 // Find the chunk at the end of the space and determine | |
| 9434 // how much it can be shrunk. | |
| 9435 size_t shrinkable_size_in_bytes = chunk_at_end->size(); | |
| 9436 size_t aligned_shrinkable_size_in_bytes = | |
| 9437 align_size_down(shrinkable_size_in_bytes, os::vm_page_size()); | |
| 6885 | 9438 assert(unallocated_start <= (HeapWord*) chunk_at_end->end(), |
| 0 | 9439 "Inconsistent chunk at end of space"); |
| 9440 size_t bytes = MIN2(desired_bytes, aligned_shrinkable_size_in_bytes); | |
| 9441 size_t word_size_before = heap_word_size(_virtual_space.committed_size()); | |
| 9442 | |
| 9443 // Shrink the underlying space | |
| 9444 _virtual_space.shrink_by(bytes); | |
| 9445 if (PrintGCDetails && Verbose) { | |
| 9446 gclog_or_tty->print_cr("ConcurrentMarkSweepGeneration::shrink_by:" | |
| 9447 " desired_bytes " SIZE_FORMAT | |
| 9448 " shrinkable_size_in_bytes " SIZE_FORMAT | |
| 9449 " aligned_shrinkable_size_in_bytes " SIZE_FORMAT | |
| 9450 " bytes " SIZE_FORMAT, | |
| 9451 desired_bytes, shrinkable_size_in_bytes, | |
| 9452 aligned_shrinkable_size_in_bytes, bytes); | |
| 9453 gclog_or_tty->print_cr(" old_end " SIZE_FORMAT | |
| 9454 " unallocated_start " SIZE_FORMAT, | |
| 9455 old_end, unallocated_start); | |
| 9456 } | |
| 9457 | |
| 9458 // If the space did shrink (shrinking is not guaranteed), | |
| 9459 // shrink the chunk at the end by the appropriate amount. | |
| 9460 if (((HeapWord*)_virtual_space.high()) < old_end) { | |
| 9461 size_t new_word_size = | |
| 9462 heap_word_size(_virtual_space.committed_size()); | |
| 9463 | |
| 9464 // Have to remove the chunk from the dictionary because it is changing | |
| 9465 // size and might be someplace elsewhere in the dictionary. | |
| 9466 | |
| 9467 // Get the chunk at end, shrink it, and put it | |
| 9468 // back. | |
| 9469 _cmsSpace->removeChunkFromDictionary(chunk_at_end); | |
| 9470 size_t word_size_change = word_size_before - new_word_size; | |
| 9471 size_t chunk_at_end_old_size = chunk_at_end->size(); | |
| 9472 assert(chunk_at_end_old_size >= word_size_change, | |
| 9473 "Shrink is too large"); | |
|
6028
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
parents:
6026
diff
changeset
|
9474 chunk_at_end->set_size(chunk_at_end_old_size - |
| 0 | 9475 word_size_change); |
| 9476 _cmsSpace->freed((HeapWord*) chunk_at_end->end(), | |
| 9477 word_size_change); | |
| 9478 | |
| 9479 _cmsSpace->returnChunkToDictionary(chunk_at_end); | |
| 9480 | |
| 9481 MemRegion mr(_cmsSpace->bottom(), new_word_size); | |
| 9482 _bts->resize(new_word_size); // resize the block offset shared array | |
| 9483 Universe::heap()->barrier_set()->resize_covered_region(mr); | |
| 9484 _cmsSpace->assert_locked(); | |
| 9485 _cmsSpace->set_end((HeapWord*)_virtual_space.high()); | |
| 9486 | |
| 9487 NOT_PRODUCT(_cmsSpace->dictionary()->verify()); | |
| 9488 | |
| 9489 // update the space and generation capacity counters | |
| 9490 if (UsePerfData) { | |
| 9491 _space_counters->update_capacity(); | |
| 9492 _gen_counters->update_all(); | |
| 9493 } | |
| 9494 | |
| 9495 if (Verbose && PrintGCDetails) { | |
| 9496 size_t new_mem_size = _virtual_space.committed_size(); | |
| 9497 size_t old_mem_size = new_mem_size + bytes; | |
|
7623
203f64878aab
7102489: RFE: cleanup jlong typedef on __APPLE__and _LLP64 systems.
hseigel
parents:
6885
diff
changeset
|
9498 gclog_or_tty->print_cr("Shrinking %s from " SIZE_FORMAT "K by " SIZE_FORMAT "K to " SIZE_FORMAT "K", |
| 0 | 9499 name(), old_mem_size/K, bytes/K, new_mem_size/K); |
| 9500 } | |
| 9501 } | |
| 9502 | |
| 9503 assert(_cmsSpace->unallocated_block() <= _cmsSpace->end(), | |
| 9504 "Inconsistency at end of space"); | |
| 6885 | 9505 assert(chunk_at_end->end() == (uintptr_t*) _cmsSpace->end(), |
| 0 | 9506 "Shrinking is inconsistent"); |
| 9507 return; | |
| 9508 } | |
| 9509 } | |
| 9510 // Transfer some number of overflown objects to usual marking | |
| 9511 // stack. Return true if some objects were transferred. | |
| 9512 bool MarkRefsIntoAndScanClosure::take_from_overflow_list() { | |
|
679
cea947c8a988
6819891: ParNew: Fix work queue overflow code to deal correctly with +UseCompressedOops
ysr
parents:
628
diff
changeset
|
9513 size_t num = MIN2((size_t)(_mark_stack->capacity() - _mark_stack->length())/4, |
| 0 | 9514 (size_t)ParGCDesiredObjsFromOverflowList); |
| 9515 | |
| 9516 bool res = _collector->take_from_overflow_list(num, _mark_stack); | |
| 9517 assert(_collector->overflow_list_is_empty() || res, | |
| 9518 "If list is not empty, we should have taken something"); | |
| 9519 assert(!res || !_mark_stack->isEmpty(), | |
| 9520 "If we took something, it should now be on our stack"); | |
| 9521 return res; | |
| 9522 } | |
| 9523 | |
| 9524 size_t MarkDeadObjectsClosure::do_blk(HeapWord* addr) { | |
| 9525 size_t res = _sp->block_size_no_stall(addr, _collector); | |
| 9526 if (_sp->block_is_obj(addr)) { | |
| 9527 if (_live_bit_map->isMarked(addr)) { | |
| 9528 // It can't have been dead in a previous cycle | |
| 9529 guarantee(!_dead_bit_map->isMarked(addr), "No resurrection!"); | |
| 9530 } else { | |
| 9531 _dead_bit_map->mark(addr); // mark the dead object | |
| 9532 } | |
| 9533 } | |
|
2226
c5a923563727
6912621: iCMS: Error: assert(_markBitMap.isMarked(addr + 1),"Missing Printezis bit?")
ysr
parents:
2177
diff
changeset
|
9534 // Could be 0, if the block size could not be computed without stalling. |
| 0 | 9535 return res; |
| 9536 } | |
|
1703
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9537 |
|
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
parents:
3293
diff
changeset
|
9538 TraceCMSMemoryManagerStats::TraceCMSMemoryManagerStats(CMSCollector::CollectorState phase, GCCause::Cause cause): TraceMemoryManagerStats() { |
|
1703
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9539 |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9540 switch (phase) { |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9541 case CMSCollector::InitialMarking: |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9542 initialize(true /* fullGC */ , |
|
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
parents:
3293
diff
changeset
|
9543 cause /* cause of the GC */, |
|
1703
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9544 true /* recordGCBeginTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9545 true /* recordPreGCUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9546 false /* recordPeakUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9547 false /* recordPostGCusage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9548 true /* recordAccumulatedGCTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9549 false /* recordGCEndTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9550 false /* countCollection */ ); |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9551 break; |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9552 |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9553 case CMSCollector::FinalMarking: |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9554 initialize(true /* fullGC */ , |
|
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
parents:
3293
diff
changeset
|
9555 cause /* cause of the GC */, |
|
1703
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9556 false /* recordGCBeginTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9557 false /* recordPreGCUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9558 false /* recordPeakUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9559 false /* recordPostGCusage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9560 true /* recordAccumulatedGCTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9561 false /* recordGCEndTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9562 false /* countCollection */ ); |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9563 break; |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9564 |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9565 case CMSCollector::Sweeping: |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9566 initialize(true /* fullGC */ , |
|
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
parents:
3293
diff
changeset
|
9567 cause /* cause of the GC */, |
|
1703
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9568 false /* recordGCBeginTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9569 false /* recordPreGCUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9570 true /* recordPeakUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9571 true /* recordPostGCusage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9572 false /* recordAccumulatedGCTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9573 true /* recordGCEndTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9574 true /* countCollection */ ); |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9575 break; |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9576 |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9577 default: |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9578 ShouldNotReachHere(); |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9579 } |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9580 } |