Mercurial > hg > graal-compiler
annotate src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp @ 21811:22ac20a25842
8055479: TLAB stability
Reviewed-by: brutisso, stefank, ahgross
| author | mgerdin |
|---|---|
| date | Thu, 09 Oct 2014 15:42:23 +0200 |
| parents | 8e20ef014b08 |
| children | c2844108a708 |
| 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" | |
| 52 #include "memory/iterator.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" | |
| 62 #include "runtime/vmThread.hpp" | |
| 63 #include "services/memoryService.hpp" | |
| 64 #include "services/runtimeService.hpp" | |
| 0 | 65 |
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66 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC |
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67 |
| 0 | 68 // statics |
| 69 CMSCollector* ConcurrentMarkSweepGeneration::_collector = NULL; | |
| 10405 | 70 bool CMSCollector::_full_gc_requested = false; |
| 71 GCCause::Cause CMSCollector::_full_gc_cause = GCCause::_no_gc; | |
| 0 | 72 |
| 73 ////////////////////////////////////////////////////////////////// | |
| 74 // In support of CMS/VM thread synchronization | |
| 75 ////////////////////////////////////////////////////////////////// | |
| 76 // We split use of the CGC_lock into 2 "levels". | |
| 77 // The low-level locking is of the usual CGC_lock monitor. We introduce | |
| 78 // a higher level "token" (hereafter "CMS token") built on top of the | |
| 79 // low level monitor (hereafter "CGC lock"). | |
| 80 // The token-passing protocol gives priority to the VM thread. The | |
| 81 // CMS-lock doesn't provide any fairness guarantees, but clients | |
| 82 // should ensure that it is only held for very short, bounded | |
| 83 // durations. | |
| 84 // | |
| 85 // When either of the CMS thread or the VM thread is involved in | |
| 86 // collection operations during which it does not want the other | |
| 87 // thread to interfere, it obtains the CMS token. | |
| 88 // | |
| 89 // If either thread tries to get the token while the other has | |
| 90 // it, that thread waits. However, if the VM thread and CMS thread | |
| 91 // both want the token, then the VM thread gets priority while the | |
| 92 // CMS thread waits. This ensures, for instance, that the "concurrent" | |
| 93 // phases of the CMS thread's work do not block out the VM thread | |
| 94 // for long periods of time as the CMS thread continues to hog | |
| 95 // the token. (See bug 4616232). | |
| 96 // | |
| 97 // The baton-passing functions are, however, controlled by the | |
| 98 // flags _foregroundGCShouldWait and _foregroundGCIsActive, | |
| 99 // and here the low-level CMS lock, not the high level token, | |
| 100 // ensures mutual exclusion. | |
| 101 // | |
| 102 // Two important conditions that we have to satisfy: | |
| 103 // 1. if a thread does a low-level wait on the CMS lock, then it | |
| 104 // relinquishes the CMS token if it were holding that token | |
| 105 // when it acquired the low-level CMS lock. | |
| 106 // 2. any low-level notifications on the low-level lock | |
| 107 // should only be sent when a thread has relinquished the token. | |
| 108 // | |
| 109 // In the absence of either property, we'd have potential deadlock. | |
| 110 // | |
| 111 // We protect each of the CMS (concurrent and sequential) phases | |
| 112 // with the CMS _token_, not the CMS _lock_. | |
| 113 // | |
| 114 // The only code protected by CMS lock is the token acquisition code | |
| 115 // itself, see ConcurrentMarkSweepThread::[de]synchronize(), and the | |
| 116 // baton-passing code. | |
| 117 // | |
| 118 // Unfortunately, i couldn't come up with a good abstraction to factor and | |
| 119 // hide the naked CGC_lock manipulation in the baton-passing code | |
| 120 // further below. That's something we should try to do. Also, the proof | |
| 121 // of correctness of this 2-level locking scheme is far from obvious, | |
| 122 // and potentially quite slippery. We have an uneasy supsicion, for instance, | |
| 123 // that there may be a theoretical possibility of delay/starvation in the | |
| 124 // low-level lock/wait/notify scheme used for the baton-passing because of | |
| 125 // potential intereference with the priority scheme embodied in the | |
| 126 // CMS-token-passing protocol. See related comments at a CGC_lock->wait() | |
| 127 // invocation further below and marked with "XXX 20011219YSR". | |
| 128 // Indeed, as we note elsewhere, this may become yet more slippery | |
| 129 // in the presence of multiple CMS and/or multiple VM threads. XXX | |
| 130 | |
| 131 class CMSTokenSync: public StackObj { | |
| 132 private: | |
| 133 bool _is_cms_thread; | |
| 134 public: | |
| 135 CMSTokenSync(bool is_cms_thread): | |
| 136 _is_cms_thread(is_cms_thread) { | |
| 137 assert(is_cms_thread == Thread::current()->is_ConcurrentGC_thread(), | |
| 138 "Incorrect argument to constructor"); | |
| 139 ConcurrentMarkSweepThread::synchronize(_is_cms_thread); | |
| 140 } | |
| 141 | |
| 142 ~CMSTokenSync() { | |
| 143 assert(_is_cms_thread ? | |
| 144 ConcurrentMarkSweepThread::cms_thread_has_cms_token() : | |
| 145 ConcurrentMarkSweepThread::vm_thread_has_cms_token(), | |
| 146 "Incorrect state"); | |
| 147 ConcurrentMarkSweepThread::desynchronize(_is_cms_thread); | |
| 148 } | |
| 149 }; | |
| 150 | |
| 151 // Convenience class that does a CMSTokenSync, and then acquires | |
| 152 // upto three locks. | |
| 153 class CMSTokenSyncWithLocks: public CMSTokenSync { | |
| 154 private: | |
| 155 // Note: locks are acquired in textual declaration order | |
| 156 // and released in the opposite order | |
| 157 MutexLockerEx _locker1, _locker2, _locker3; | |
| 158 public: | |
| 159 CMSTokenSyncWithLocks(bool is_cms_thread, Mutex* mutex1, | |
| 160 Mutex* mutex2 = NULL, Mutex* mutex3 = NULL): | |
| 161 CMSTokenSync(is_cms_thread), | |
| 162 _locker1(mutex1, Mutex::_no_safepoint_check_flag), | |
| 163 _locker2(mutex2, Mutex::_no_safepoint_check_flag), | |
| 164 _locker3(mutex3, Mutex::_no_safepoint_check_flag) | |
| 165 { } | |
| 166 }; | |
| 167 | |
| 168 | |
| 169 // Wrapper class to temporarily disable icms during a foreground cms collection. | |
| 170 class ICMSDisabler: public StackObj { | |
| 171 public: | |
| 172 // The ctor disables icms and wakes up the thread so it notices the change; | |
| 173 // the dtor re-enables icms. Note that the CMSCollector methods will check | |
| 174 // CMSIncrementalMode. | |
| 175 ICMSDisabler() { CMSCollector::disable_icms(); CMSCollector::start_icms(); } | |
| 176 ~ICMSDisabler() { CMSCollector::enable_icms(); } | |
| 177 }; | |
| 178 | |
| 179 ////////////////////////////////////////////////////////////////// | |
| 180 // Concurrent Mark-Sweep Generation ///////////////////////////// | |
| 181 ////////////////////////////////////////////////////////////////// | |
| 182 | |
| 183 NOT_PRODUCT(CompactibleFreeListSpace* debug_cms_space;) | |
| 184 | |
| 185 // This struct contains per-thread things necessary to support parallel | |
| 186 // young-gen collection. | |
| 6197 | 187 class CMSParGCThreadState: public CHeapObj<mtGC> { |
| 0 | 188 public: |
| 189 CFLS_LAB lab; | |
| 190 PromotionInfo promo; | |
| 191 | |
| 192 // Constructor. | |
| 193 CMSParGCThreadState(CompactibleFreeListSpace* cfls) : lab(cfls) { | |
| 194 promo.setSpace(cfls); | |
| 195 } | |
| 196 }; | |
| 197 | |
| 198 ConcurrentMarkSweepGeneration::ConcurrentMarkSweepGeneration( | |
| 199 ReservedSpace rs, size_t initial_byte_size, int level, | |
| 200 CardTableRS* ct, bool use_adaptive_freelists, | |
| 6026 | 201 FreeBlockDictionary<FreeChunk>::DictionaryChoice dictionaryChoice) : |
| 0 | 202 CardGeneration(rs, initial_byte_size, level, ct), |
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203 _dilatation_factor(((double)MinChunkSize)/((double)(CollectedHeap::min_fill_size()))), |
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204 _debug_collection_type(Concurrent_collection_type), |
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205 _did_compact(false) |
| 0 | 206 { |
| 207 HeapWord* bottom = (HeapWord*) _virtual_space.low(); | |
| 208 HeapWord* end = (HeapWord*) _virtual_space.high(); | |
| 209 | |
| 210 _direct_allocated_words = 0; | |
| 211 NOT_PRODUCT( | |
| 212 _numObjectsPromoted = 0; | |
| 213 _numWordsPromoted = 0; | |
| 214 _numObjectsAllocated = 0; | |
| 215 _numWordsAllocated = 0; | |
| 216 ) | |
| 217 | |
| 218 _cmsSpace = new CompactibleFreeListSpace(_bts, MemRegion(bottom, end), | |
| 219 use_adaptive_freelists, | |
| 220 dictionaryChoice); | |
| 221 NOT_PRODUCT(debug_cms_space = _cmsSpace;) | |
| 222 if (_cmsSpace == NULL) { | |
| 223 vm_exit_during_initialization( | |
| 224 "CompactibleFreeListSpace allocation failure"); | |
| 225 } | |
| 226 _cmsSpace->_gen = this; | |
| 227 | |
| 228 _gc_stats = new CMSGCStats(); | |
| 229 | |
| 230 // Verify the assumption that FreeChunk::_prev and OopDesc::_klass | |
| 231 // offsets match. The ability to tell free chunks from objects | |
| 232 // depends on this property. | |
| 233 debug_only( | |
| 234 FreeChunk* junk = NULL; | |
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235 assert(UseCompressedClassPointers || |
| 187 | 236 junk->prev_addr() == (void*)(oop(junk)->klass_addr()), |
| 0 | 237 "Offset of FreeChunk::_prev within FreeChunk must match" |
| 238 " that of OopDesc::_klass within OopDesc"); | |
| 239 ) | |
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240 if (CollectedHeap::use_parallel_gc_threads()) { |
| 0 | 241 typedef CMSParGCThreadState* CMSParGCThreadStatePtr; |
| 242 _par_gc_thread_states = | |
| 6197 | 243 NEW_C_HEAP_ARRAY(CMSParGCThreadStatePtr, ParallelGCThreads, mtGC); |
| 0 | 244 if (_par_gc_thread_states == NULL) { |
| 245 vm_exit_during_initialization("Could not allocate par gc structs"); | |
| 246 } | |
| 247 for (uint i = 0; i < ParallelGCThreads; i++) { | |
| 248 _par_gc_thread_states[i] = new CMSParGCThreadState(cmsSpace()); | |
| 249 if (_par_gc_thread_states[i] == NULL) { | |
| 250 vm_exit_during_initialization("Could not allocate par gc structs"); | |
| 251 } | |
| 252 } | |
| 253 } else { | |
| 254 _par_gc_thread_states = NULL; | |
| 255 } | |
| 256 _incremental_collection_failed = false; | |
| 257 // The "dilatation_factor" is the expansion that can occur on | |
| 258 // account of the fact that the minimum object size in the CMS | |
| 259 // generation may be larger than that in, say, a contiguous young | |
| 260 // generation. | |
| 261 // Ideally, in the calculation below, we'd compute the dilatation | |
| 262 // factor as: MinChunkSize/(promoting_gen's min object size) | |
| 263 // Since we do not have such a general query interface for the | |
| 264 // promoting generation, we'll instead just use the mimimum | |
| 265 // object size (which today is a header's worth of space); | |
| 266 // note that all arithmetic is in units of HeapWords. | |
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267 assert(MinChunkSize >= CollectedHeap::min_fill_size(), "just checking"); |
| 0 | 268 assert(_dilatation_factor >= 1.0, "from previous assert"); |
| 269 } | |
| 270 | |
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271 |
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272 // The field "_initiating_occupancy" represents the occupancy percentage |
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273 // at which we trigger a new collection cycle. Unless explicitly specified |
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274 // via CMSInitiatingOccupancyFraction (argument "io" below), it |
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275 // is calculated by: |
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276 // |
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277 // Let "f" be MinHeapFreeRatio in |
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278 // |
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279 // _intiating_occupancy = 100-f + |
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280 // f * (CMSTriggerRatio/100) |
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281 // where CMSTriggerRatio is the argument "tr" below. |
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282 // |
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283 // That is, if we assume the heap is at its desired maximum occupancy at the |
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284 // end of a collection, we let CMSTriggerRatio of the (purported) free |
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285 // space be allocated before initiating a new collection cycle. |
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286 // |
| 8035 | 287 void ConcurrentMarkSweepGeneration::init_initiating_occupancy(intx io, uintx tr) { |
| 288 assert(io <= 100 && tr <= 100, "Check the arguments"); | |
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289 if (io >= 0) { |
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290 _initiating_occupancy = (double)io / 100.0; |
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291 } else { |
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292 _initiating_occupancy = ((100 - MinHeapFreeRatio) + |
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293 (double)(tr * MinHeapFreeRatio) / 100.0) |
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294 / 100.0; |
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295 } |
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296 } |
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297 |
| 0 | 298 void ConcurrentMarkSweepGeneration::ref_processor_init() { |
| 299 assert(collector() != NULL, "no collector"); | |
| 300 collector()->ref_processor_init(); | |
| 301 } | |
| 302 | |
| 303 void CMSCollector::ref_processor_init() { | |
| 304 if (_ref_processor == NULL) { | |
| 305 // Allocate and initialize a reference processor | |
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306 _ref_processor = |
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307 new ReferenceProcessor(_span, // span |
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308 (ParallelGCThreads > 1) && ParallelRefProcEnabled, // mt processing |
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309 (int) ParallelGCThreads, // mt processing degree |
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310 _cmsGen->refs_discovery_is_mt(), // mt discovery |
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311 (int) MAX2(ConcGCThreads, ParallelGCThreads), // mt discovery degree |
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312 _cmsGen->refs_discovery_is_atomic(), // discovery is not atomic |
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313 &_is_alive_closure); // closure for liveness info |
| 0 | 314 // Initialize the _ref_processor field of CMSGen |
| 315 _cmsGen->set_ref_processor(_ref_processor); | |
| 316 | |
| 317 } | |
| 318 } | |
| 319 | |
| 320 CMSAdaptiveSizePolicy* CMSCollector::size_policy() { | |
| 321 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 322 assert(gch->kind() == CollectedHeap::GenCollectedHeap, | |
| 323 "Wrong type of heap"); | |
| 324 CMSAdaptiveSizePolicy* sp = (CMSAdaptiveSizePolicy*) | |
| 325 gch->gen_policy()->size_policy(); | |
| 326 assert(sp->is_gc_cms_adaptive_size_policy(), | |
| 327 "Wrong type of size policy"); | |
| 328 return sp; | |
| 329 } | |
| 330 | |
| 331 CMSGCAdaptivePolicyCounters* CMSCollector::gc_adaptive_policy_counters() { | |
| 332 CMSGCAdaptivePolicyCounters* results = | |
| 333 (CMSGCAdaptivePolicyCounters*) collector_policy()->counters(); | |
| 334 assert( | |
| 335 results->kind() == GCPolicyCounters::CMSGCAdaptivePolicyCountersKind, | |
| 336 "Wrong gc policy counter kind"); | |
| 337 return results; | |
| 338 } | |
| 339 | |
| 340 | |
| 341 void ConcurrentMarkSweepGeneration::initialize_performance_counters() { | |
| 342 | |
| 343 const char* gen_name = "old"; | |
| 344 | |
| 345 // Generation Counters - generation 1, 1 subspace | |
| 346 _gen_counters = new GenerationCounters(gen_name, 1, 1, &_virtual_space); | |
| 347 | |
| 348 _space_counters = new GSpaceCounters(gen_name, 0, | |
| 349 _virtual_space.reserved_size(), | |
| 350 this, _gen_counters); | |
| 351 } | |
| 352 | |
| 353 CMSStats::CMSStats(ConcurrentMarkSweepGeneration* cms_gen, unsigned int alpha): | |
| 354 _cms_gen(cms_gen) | |
| 355 { | |
| 356 assert(alpha <= 100, "bad value"); | |
| 357 _saved_alpha = alpha; | |
| 358 | |
| 359 // Initialize the alphas to the bootstrap value of 100. | |
| 360 _gc0_alpha = _cms_alpha = 100; | |
| 361 | |
| 362 _cms_begin_time.update(); | |
| 363 _cms_end_time.update(); | |
| 364 | |
| 365 _gc0_duration = 0.0; | |
| 366 _gc0_period = 0.0; | |
| 367 _gc0_promoted = 0; | |
| 368 | |
| 369 _cms_duration = 0.0; | |
| 370 _cms_period = 0.0; | |
| 371 _cms_allocated = 0; | |
| 372 | |
| 373 _cms_used_at_gc0_begin = 0; | |
| 374 _cms_used_at_gc0_end = 0; | |
| 375 _allow_duty_cycle_reduction = false; | |
| 376 _valid_bits = 0; | |
| 377 _icms_duty_cycle = CMSIncrementalDutyCycle; | |
| 378 } | |
| 379 | |
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380 double CMSStats::cms_free_adjustment_factor(size_t free) const { |
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381 // TBD: CR 6909490 |
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382 return 1.0; |
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383 } |
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384 |
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385 void CMSStats::adjust_cms_free_adjustment_factor(bool fail, size_t free) { |
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386 } |
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387 |
| 0 | 388 // If promotion failure handling is on use |
| 389 // the padded average size of the promotion for each | |
| 390 // young generation collection. | |
| 391 double CMSStats::time_until_cms_gen_full() const { | |
| 392 size_t cms_free = _cms_gen->cmsSpace()->free(); | |
| 393 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
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394 size_t expected_promotion = MIN2(gch->get_gen(0)->capacity(), |
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395 (size_t) _cms_gen->gc_stats()->avg_promoted()->padded_average()); |
| 0 | 396 if (cms_free > expected_promotion) { |
| 397 // Start a cms collection if there isn't enough space to promote | |
| 398 // for the next minor collection. Use the padded average as | |
| 399 // a safety factor. | |
| 400 cms_free -= expected_promotion; | |
| 401 | |
| 402 // Adjust by the safety factor. | |
| 403 double cms_free_dbl = (double)cms_free; | |
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404 double cms_adjustment = (100.0 - CMSIncrementalSafetyFactor)/100.0; |
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405 // Apply a further correction factor which tries to adjust |
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406 // for recent occurance of concurrent mode failures. |
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407 cms_adjustment = cms_adjustment * cms_free_adjustment_factor(cms_free); |
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408 cms_free_dbl = cms_free_dbl * cms_adjustment; |
| 0 | 409 |
| 410 if (PrintGCDetails && Verbose) { | |
| 411 gclog_or_tty->print_cr("CMSStats::time_until_cms_gen_full: cms_free " | |
| 412 SIZE_FORMAT " expected_promotion " SIZE_FORMAT, | |
| 413 cms_free, expected_promotion); | |
| 414 gclog_or_tty->print_cr(" cms_free_dbl %f cms_consumption_rate %f", | |
| 415 cms_free_dbl, cms_consumption_rate() + 1.0); | |
| 416 } | |
| 417 // Add 1 in case the consumption rate goes to zero. | |
| 418 return cms_free_dbl / (cms_consumption_rate() + 1.0); | |
| 419 } | |
| 420 return 0.0; | |
| 421 } | |
| 422 | |
| 423 // Compare the duration of the cms collection to the | |
| 424 // time remaining before the cms generation is empty. | |
| 425 // Note that the time from the start of the cms collection | |
| 426 // to the start of the cms sweep (less than the total | |
| 427 // duration of the cms collection) can be used. This | |
| 428 // has been tried and some applications experienced | |
| 429 // promotion failures early in execution. This was | |
| 430 // possibly because the averages were not accurate | |
| 431 // enough at the beginning. | |
| 432 double CMSStats::time_until_cms_start() const { | |
| 433 // We add "gc0_period" to the "work" calculation | |
| 434 // below because this query is done (mostly) at the | |
| 435 // end of a scavenge, so we need to conservatively | |
| 436 // account for that much possible delay | |
| 437 // in the query so as to avoid concurrent mode failures | |
| 438 // due to starting the collection just a wee bit too | |
| 439 // late. | |
| 440 double work = cms_duration() + gc0_period(); | |
| 441 double deadline = time_until_cms_gen_full(); | |
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442 // If a concurrent mode failure occurred recently, we want to be |
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443 // more conservative and halve our expected time_until_cms_gen_full() |
| 0 | 444 if (work > deadline) { |
| 445 if (Verbose && PrintGCDetails) { | |
| 446 gclog_or_tty->print( | |
| 447 " CMSCollector: collect because of anticipated promotion " | |
| 448 "before full %3.7f + %3.7f > %3.7f ", cms_duration(), | |
| 449 gc0_period(), time_until_cms_gen_full()); | |
| 450 } | |
| 451 return 0.0; | |
| 452 } | |
| 453 return work - deadline; | |
| 454 } | |
| 455 | |
| 456 // Return a duty cycle based on old_duty_cycle and new_duty_cycle, limiting the | |
| 457 // amount of change to prevent wild oscillation. | |
| 458 unsigned int CMSStats::icms_damped_duty_cycle(unsigned int old_duty_cycle, | |
| 459 unsigned int new_duty_cycle) { | |
| 460 assert(old_duty_cycle <= 100, "bad input value"); | |
| 461 assert(new_duty_cycle <= 100, "bad input value"); | |
| 462 | |
| 463 // Note: use subtraction with caution since it may underflow (values are | |
| 464 // unsigned). Addition is safe since we're in the range 0-100. | |
| 465 unsigned int damped_duty_cycle = new_duty_cycle; | |
| 466 if (new_duty_cycle < old_duty_cycle) { | |
| 467 const unsigned int largest_delta = MAX2(old_duty_cycle / 4, 5U); | |
| 468 if (new_duty_cycle + largest_delta < old_duty_cycle) { | |
| 469 damped_duty_cycle = old_duty_cycle - largest_delta; | |
| 470 } | |
| 471 } else if (new_duty_cycle > old_duty_cycle) { | |
| 472 const unsigned int largest_delta = MAX2(old_duty_cycle / 4, 15U); | |
| 473 if (new_duty_cycle > old_duty_cycle + largest_delta) { | |
| 474 damped_duty_cycle = MIN2(old_duty_cycle + largest_delta, 100U); | |
| 475 } | |
| 476 } | |
| 477 assert(damped_duty_cycle <= 100, "invalid duty cycle computed"); | |
| 478 | |
| 479 if (CMSTraceIncrementalPacing) { | |
| 480 gclog_or_tty->print(" [icms_damped_duty_cycle(%d,%d) = %d] ", | |
| 481 old_duty_cycle, new_duty_cycle, damped_duty_cycle); | |
| 482 } | |
| 483 return damped_duty_cycle; | |
| 484 } | |
| 485 | |
| 486 unsigned int CMSStats::icms_update_duty_cycle_impl() { | |
| 487 assert(CMSIncrementalPacing && valid(), | |
| 488 "should be handled in icms_update_duty_cycle()"); | |
| 489 | |
| 490 double cms_time_so_far = cms_timer().seconds(); | |
| 491 double scaled_duration = cms_duration_per_mb() * _cms_used_at_gc0_end / M; | |
| 492 double scaled_duration_remaining = fabsd(scaled_duration - cms_time_so_far); | |
| 493 | |
| 494 // Avoid division by 0. | |
| 495 double time_until_full = MAX2(time_until_cms_gen_full(), 0.01); | |
| 496 double duty_cycle_dbl = 100.0 * scaled_duration_remaining / time_until_full; | |
| 497 | |
| 498 unsigned int new_duty_cycle = MIN2((unsigned int)duty_cycle_dbl, 100U); | |
| 499 if (new_duty_cycle > _icms_duty_cycle) { | |
| 500 // Avoid very small duty cycles (1 or 2); 0 is allowed. | |
| 501 if (new_duty_cycle > 2) { | |
| 502 _icms_duty_cycle = icms_damped_duty_cycle(_icms_duty_cycle, | |
| 503 new_duty_cycle); | |
| 504 } | |
| 505 } else if (_allow_duty_cycle_reduction) { | |
| 506 // The duty cycle is reduced only once per cms cycle (see record_cms_end()). | |
| 507 new_duty_cycle = icms_damped_duty_cycle(_icms_duty_cycle, new_duty_cycle); | |
| 508 // Respect the minimum duty cycle. | |
| 509 unsigned int min_duty_cycle = (unsigned int)CMSIncrementalDutyCycleMin; | |
| 510 _icms_duty_cycle = MAX2(new_duty_cycle, min_duty_cycle); | |
| 511 } | |
| 512 | |
| 513 if (PrintGCDetails || CMSTraceIncrementalPacing) { | |
| 514 gclog_or_tty->print(" icms_dc=%d ", _icms_duty_cycle); | |
| 515 } | |
| 516 | |
| 517 _allow_duty_cycle_reduction = false; | |
| 518 return _icms_duty_cycle; | |
| 519 } | |
| 520 | |
| 521 #ifndef PRODUCT | |
| 522 void CMSStats::print_on(outputStream *st) const { | |
| 523 st->print(" gc0_alpha=%d,cms_alpha=%d", _gc0_alpha, _cms_alpha); | |
| 524 st->print(",gc0_dur=%g,gc0_per=%g,gc0_promo=" SIZE_FORMAT, | |
| 525 gc0_duration(), gc0_period(), gc0_promoted()); | |
| 526 st->print(",cms_dur=%g,cms_dur_per_mb=%g,cms_per=%g,cms_alloc=" SIZE_FORMAT, | |
| 527 cms_duration(), cms_duration_per_mb(), | |
| 528 cms_period(), cms_allocated()); | |
| 529 st->print(",cms_since_beg=%g,cms_since_end=%g", | |
| 530 cms_time_since_begin(), cms_time_since_end()); | |
| 531 st->print(",cms_used_beg=" SIZE_FORMAT ",cms_used_end=" SIZE_FORMAT, | |
| 532 _cms_used_at_gc0_begin, _cms_used_at_gc0_end); | |
| 533 if (CMSIncrementalMode) { | |
| 534 st->print(",dc=%d", icms_duty_cycle()); | |
| 535 } | |
| 536 | |
| 537 if (valid()) { | |
| 538 st->print(",promo_rate=%g,cms_alloc_rate=%g", | |
| 539 promotion_rate(), cms_allocation_rate()); | |
| 540 st->print(",cms_consumption_rate=%g,time_until_full=%g", | |
| 541 cms_consumption_rate(), time_until_cms_gen_full()); | |
| 542 } | |
| 543 st->print(" "); | |
| 544 } | |
| 545 #endif // #ifndef PRODUCT | |
| 546 | |
| 547 CMSCollector::CollectorState CMSCollector::_collectorState = | |
| 548 CMSCollector::Idling; | |
| 549 bool CMSCollector::_foregroundGCIsActive = false; | |
| 550 bool CMSCollector::_foregroundGCShouldWait = false; | |
| 551 | |
| 552 CMSCollector::CMSCollector(ConcurrentMarkSweepGeneration* cmsGen, | |
| 553 CardTableRS* ct, | |
| 554 ConcurrentMarkSweepPolicy* cp): | |
| 555 _cmsGen(cmsGen), | |
| 556 _ct(ct), | |
| 557 _ref_processor(NULL), // will be set later | |
| 558 _conc_workers(NULL), // may be set later | |
| 559 _abort_preclean(false), | |
| 560 _start_sampling(false), | |
| 561 _between_prologue_and_epilogue(false), | |
| 562 _markBitMap(0, Mutex::leaf + 1, "CMS_markBitMap_lock"), | |
| 563 _modUnionTable((CardTableModRefBS::card_shift - LogHeapWordSize), | |
| 564 -1 /* lock-free */, "No_lock" /* dummy */), | |
| 565 _modUnionClosure(&_modUnionTable), | |
| 566 _modUnionClosurePar(&_modUnionTable), | |
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567 // Adjust my span to cover old (cms) gen |
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568 _span(cmsGen->reserved()), |
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569 // Construct the is_alive_closure with _span & markBitMap |
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570 _is_alive_closure(_span, &_markBitMap), |
| 0 | 571 _restart_addr(NULL), |
| 572 _overflow_list(NULL), | |
| 573 _stats(cmsGen), | |
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574 _eden_chunk_lock(new Mutex(Mutex::leaf + 1, "CMS_eden_chunk_lock", true)), |
| 0 | 575 _eden_chunk_array(NULL), // may be set in ctor body |
| 576 _eden_chunk_capacity(0), // -- ditto -- | |
| 577 _eden_chunk_index(0), // -- ditto -- | |
| 578 _survivor_plab_array(NULL), // -- ditto -- | |
| 579 _survivor_chunk_array(NULL), // -- ditto -- | |
| 580 _survivor_chunk_capacity(0), // -- ditto -- | |
| 581 _survivor_chunk_index(0), // -- ditto -- | |
| 582 _ser_pmc_preclean_ovflw(0), | |
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583 _ser_kac_preclean_ovflw(0), |
| 0 | 584 _ser_pmc_remark_ovflw(0), |
| 585 _par_pmc_remark_ovflw(0), | |
| 586 _ser_kac_ovflw(0), | |
| 587 _par_kac_ovflw(0), | |
| 588 #ifndef PRODUCT | |
| 589 _num_par_pushes(0), | |
| 590 #endif | |
| 591 _collection_count_start(0), | |
| 592 _verifying(false), | |
| 593 _icms_start_limit(NULL), | |
| 594 _icms_stop_limit(NULL), | |
| 595 _verification_mark_bm(0, Mutex::leaf + 1, "CMS_verification_mark_bm_lock"), | |
| 596 _completed_initialization(false), | |
| 597 _collector_policy(cp), | |
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598 _should_unload_classes(CMSClassUnloadingEnabled), |
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599 _concurrent_cycles_since_last_unload(0), |
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600 _roots_scanning_options(SharedHeap::SO_None), |
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601 _inter_sweep_estimate(CMS_SweepWeight, CMS_SweepPadding), |
| 10405 | 602 _intra_sweep_estimate(CMS_SweepWeight, CMS_SweepPadding), |
| 603 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) CMSTracer()), | |
| 604 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), | |
| 605 _cms_start_registered(false) | |
| 0 | 606 { |
| 607 if (ExplicitGCInvokesConcurrentAndUnloadsClasses) { | |
| 608 ExplicitGCInvokesConcurrent = true; | |
| 609 } | |
| 610 // Now expand the span and allocate the collection support structures | |
| 611 // (MUT, marking bit map etc.) to cover both generations subject to | |
| 612 // collection. | |
| 613 | |
| 614 // For use by dirty card to oop closures. | |
| 615 _cmsGen->cmsSpace()->set_collector(this); | |
| 616 | |
| 617 // Allocate MUT and marking bit map | |
| 618 { | |
| 619 MutexLockerEx x(_markBitMap.lock(), Mutex::_no_safepoint_check_flag); | |
| 620 if (!_markBitMap.allocate(_span)) { | |
| 621 warning("Failed to allocate CMS Bit Map"); | |
| 622 return; | |
| 623 } | |
| 624 assert(_markBitMap.covers(_span), "_markBitMap inconsistency?"); | |
| 625 } | |
| 626 { | |
| 627 _modUnionTable.allocate(_span); | |
| 628 assert(_modUnionTable.covers(_span), "_modUnionTable inconsistency?"); | |
| 629 } | |
| 630 | |
| 1284 | 631 if (!_markStack.allocate(MarkStackSize)) { |
| 0 | 632 warning("Failed to allocate CMS Marking Stack"); |
| 633 return; | |
| 634 } | |
| 635 | |
| 636 // Support for multi-threaded concurrent phases | |
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637 if (CMSConcurrentMTEnabled) { |
| 1284 | 638 if (FLAG_IS_DEFAULT(ConcGCThreads)) { |
| 0 | 639 // just for now |
| 1284 | 640 FLAG_SET_DEFAULT(ConcGCThreads, (ParallelGCThreads + 3)/4); |
| 641 } | |
| 642 if (ConcGCThreads > 1) { | |
| 0 | 643 _conc_workers = new YieldingFlexibleWorkGang("Parallel CMS Threads", |
| 1284 | 644 ConcGCThreads, true); |
| 0 | 645 if (_conc_workers == NULL) { |
| 646 warning("GC/CMS: _conc_workers allocation failure: " | |
| 647 "forcing -CMSConcurrentMTEnabled"); | |
| 648 CMSConcurrentMTEnabled = false; | |
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649 } else { |
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650 _conc_workers->initialize_workers(); |
| 0 | 651 } |
| 652 } else { | |
| 653 CMSConcurrentMTEnabled = false; | |
| 654 } | |
| 655 } | |
| 656 if (!CMSConcurrentMTEnabled) { | |
| 1284 | 657 ConcGCThreads = 0; |
| 0 | 658 } else { |
| 659 // Turn off CMSCleanOnEnter optimization temporarily for | |
| 660 // the MT case where it's not fixed yet; see 6178663. | |
| 661 CMSCleanOnEnter = false; | |
| 662 } | |
| 1284 | 663 assert((_conc_workers != NULL) == (ConcGCThreads > 1), |
| 0 | 664 "Inconsistency"); |
| 665 | |
| 666 // Parallel task queues; these are shared for the | |
| 667 // concurrent and stop-world phases of CMS, but | |
| 668 // are not shared with parallel scavenge (ParNew). | |
| 669 { | |
| 670 uint i; | |
| 1284 | 671 uint num_queues = (uint) MAX2(ParallelGCThreads, ConcGCThreads); |
| 0 | 672 |
| 673 if ((CMSParallelRemarkEnabled || CMSConcurrentMTEnabled | |
| 674 || ParallelRefProcEnabled) | |
| 675 && num_queues > 0) { | |
| 676 _task_queues = new OopTaskQueueSet(num_queues); | |
| 677 if (_task_queues == NULL) { | |
| 678 warning("task_queues allocation failure."); | |
| 679 return; | |
| 680 } | |
| 6197 | 681 _hash_seed = NEW_C_HEAP_ARRAY(int, num_queues, mtGC); |
| 0 | 682 if (_hash_seed == NULL) { |
| 683 warning("_hash_seed array allocation failure"); | |
| 684 return; | |
| 685 } | |
| 686 | |
| 1665 | 687 typedef Padded<OopTaskQueue> PaddedOopTaskQueue; |
| 0 | 688 for (i = 0; i < num_queues; i++) { |
| 1665 | 689 PaddedOopTaskQueue *q = new PaddedOopTaskQueue(); |
| 690 if (q == NULL) { | |
| 0 | 691 warning("work_queue allocation failure."); |
| 692 return; | |
| 693 } | |
| 1665 | 694 _task_queues->register_queue(i, q); |
| 0 | 695 } |
| 696 for (i = 0; i < num_queues; i++) { | |
| 697 _task_queues->queue(i)->initialize(); | |
| 698 _hash_seed[i] = 17; // copied from ParNew | |
| 699 } | |
| 700 } | |
| 701 } | |
| 702 | |
|
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703 _cmsGen ->init_initiating_occupancy(CMSInitiatingOccupancyFraction, CMSTriggerRatio); |
|
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704 |
| 0 | 705 // Clip CMSBootstrapOccupancy between 0 and 100. |
|
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706 _bootstrap_occupancy = ((double)CMSBootstrapOccupancy)/(double)100; |
| 0 | 707 |
| 708 _full_gcs_since_conc_gc = 0; | |
| 709 | |
| 710 // Now tell CMS generations the identity of their collector | |
| 711 ConcurrentMarkSweepGeneration::set_collector(this); | |
| 712 | |
| 713 // Create & start a CMS thread for this CMS collector | |
| 714 _cmsThread = ConcurrentMarkSweepThread::start(this); | |
| 715 assert(cmsThread() != NULL, "CMS Thread should have been created"); | |
| 716 assert(cmsThread()->collector() == this, | |
| 717 "CMS Thread should refer to this gen"); | |
| 718 assert(CGC_lock != NULL, "Where's the CGC_lock?"); | |
| 719 | |
| 720 // Support for parallelizing young gen rescan | |
| 721 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 722 _young_gen = gch->prev_gen(_cmsGen); | |
| 723 if (gch->supports_inline_contig_alloc()) { | |
| 724 _top_addr = gch->top_addr(); | |
| 725 _end_addr = gch->end_addr(); | |
| 726 assert(_young_gen != NULL, "no _young_gen"); | |
| 727 _eden_chunk_index = 0; | |
| 728 _eden_chunk_capacity = (_young_gen->max_capacity()+CMSSamplingGrain)/CMSSamplingGrain; | |
| 6197 | 729 _eden_chunk_array = NEW_C_HEAP_ARRAY(HeapWord*, _eden_chunk_capacity, mtGC); |
| 0 | 730 if (_eden_chunk_array == NULL) { |
| 731 _eden_chunk_capacity = 0; | |
| 732 warning("GC/CMS: _eden_chunk_array allocation failure"); | |
| 733 } | |
| 734 } | |
| 735 assert(_eden_chunk_array != NULL || _eden_chunk_capacity == 0, "Error"); | |
| 736 | |
| 737 // Support for parallelizing survivor space rescan | |
| 11975 | 738 if ((CMSParallelRemarkEnabled && CMSParallelSurvivorRemarkEnabled) || CMSParallelInitialMarkEnabled) { |
|
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739 const size_t max_plab_samples = |
| 21811 | 740 ((DefNewGeneration*)_young_gen)->max_survivor_size() / plab_sample_minimum_size(); |
|
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741 |
| 6197 | 742 _survivor_plab_array = NEW_C_HEAP_ARRAY(ChunkArray, ParallelGCThreads, mtGC); |
| 743 _survivor_chunk_array = NEW_C_HEAP_ARRAY(HeapWord*, 2*max_plab_samples, mtGC); | |
| 744 _cursor = NEW_C_HEAP_ARRAY(size_t, ParallelGCThreads, mtGC); | |
| 0 | 745 if (_survivor_plab_array == NULL || _survivor_chunk_array == NULL |
| 746 || _cursor == NULL) { | |
| 747 warning("Failed to allocate survivor plab/chunk array"); | |
| 748 if (_survivor_plab_array != NULL) { | |
| 6197 | 749 FREE_C_HEAP_ARRAY(ChunkArray, _survivor_plab_array, mtGC); |
| 0 | 750 _survivor_plab_array = NULL; |
| 751 } | |
| 752 if (_survivor_chunk_array != NULL) { | |
| 6197 | 753 FREE_C_HEAP_ARRAY(HeapWord*, _survivor_chunk_array, mtGC); |
| 0 | 754 _survivor_chunk_array = NULL; |
| 755 } | |
| 756 if (_cursor != NULL) { | |
| 6197 | 757 FREE_C_HEAP_ARRAY(size_t, _cursor, mtGC); |
| 0 | 758 _cursor = NULL; |
| 759 } | |
| 760 } else { | |
| 761 _survivor_chunk_capacity = 2*max_plab_samples; | |
| 762 for (uint i = 0; i < ParallelGCThreads; i++) { | |
| 6197 | 763 HeapWord** vec = NEW_C_HEAP_ARRAY(HeapWord*, max_plab_samples, mtGC); |
| 0 | 764 if (vec == NULL) { |
| 765 warning("Failed to allocate survivor plab array"); | |
| 766 for (int j = i; j > 0; j--) { | |
| 6197 | 767 FREE_C_HEAP_ARRAY(HeapWord*, _survivor_plab_array[j-1].array(), mtGC); |
| 0 | 768 } |
| 6197 | 769 FREE_C_HEAP_ARRAY(ChunkArray, _survivor_plab_array, mtGC); |
| 770 FREE_C_HEAP_ARRAY(HeapWord*, _survivor_chunk_array, mtGC); | |
| 0 | 771 _survivor_plab_array = NULL; |
| 772 _survivor_chunk_array = NULL; | |
| 773 _survivor_chunk_capacity = 0; | |
| 774 break; | |
| 775 } else { | |
| 776 ChunkArray* cur = | |
| 777 ::new (&_survivor_plab_array[i]) ChunkArray(vec, | |
| 778 max_plab_samples); | |
| 779 assert(cur->end() == 0, "Should be 0"); | |
| 780 assert(cur->array() == vec, "Should be vec"); | |
| 781 assert(cur->capacity() == max_plab_samples, "Error"); | |
| 782 } | |
| 783 } | |
| 784 } | |
| 785 } | |
| 786 assert( ( _survivor_plab_array != NULL | |
| 787 && _survivor_chunk_array != NULL) | |
| 788 || ( _survivor_chunk_capacity == 0 | |
| 789 && _survivor_chunk_index == 0), | |
| 790 "Error"); | |
| 791 | |
| 792 NOT_PRODUCT(_overflow_counter = CMSMarkStackOverflowInterval;) | |
| 793 _gc_counters = new CollectorCounters("CMS", 1); | |
| 794 _completed_initialization = true; | |
|
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795 _inter_sweep_timer.start(); // start of time |
| 0 | 796 } |
| 797 | |
| 21811 | 798 size_t CMSCollector::plab_sample_minimum_size() { |
| 799 // The default value of MinTLABSize is 2k, but there is | |
| 800 // no way to get the default value if the flag has been overridden. | |
| 801 return MAX2(ThreadLocalAllocBuffer::min_size() * HeapWordSize, 2 * K); | |
| 802 } | |
| 803 | |
| 0 | 804 const char* ConcurrentMarkSweepGeneration::name() const { |
| 805 return "concurrent mark-sweep generation"; | |
| 806 } | |
| 807 void ConcurrentMarkSweepGeneration::update_counters() { | |
| 808 if (UsePerfData) { | |
| 809 _space_counters->update_all(); | |
| 810 _gen_counters->update_all(); | |
| 811 } | |
| 812 } | |
| 813 | |
| 814 // this is an optimized version of update_counters(). it takes the | |
| 815 // used value as a parameter rather than computing it. | |
| 816 // | |
| 817 void ConcurrentMarkSweepGeneration::update_counters(size_t used) { | |
| 818 if (UsePerfData) { | |
| 819 _space_counters->update_used(used); | |
| 820 _space_counters->update_capacity(); | |
| 821 _gen_counters->update_all(); | |
| 822 } | |
| 823 } | |
| 824 | |
| 825 void ConcurrentMarkSweepGeneration::print() const { | |
| 826 Generation::print(); | |
| 827 cmsSpace()->print(); | |
| 828 } | |
| 829 | |
| 830 #ifndef PRODUCT | |
| 831 void ConcurrentMarkSweepGeneration::print_statistics() { | |
| 832 cmsSpace()->printFLCensus(0); | |
| 833 } | |
| 834 #endif | |
| 835 | |
| 836 void ConcurrentMarkSweepGeneration::printOccupancy(const char *s) { | |
| 837 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 838 if (PrintGCDetails) { | |
| 839 if (Verbose) { | |
|
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840 gclog_or_tty->print("[%d %s-%s: "SIZE_FORMAT"("SIZE_FORMAT")]", |
| 0 | 841 level(), short_name(), s, used(), capacity()); |
| 842 } else { | |
|
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843 gclog_or_tty->print("[%d %s-%s: "SIZE_FORMAT"K("SIZE_FORMAT"K)]", |
| 0 | 844 level(), short_name(), s, used() / K, capacity() / K); |
| 845 } | |
| 846 } | |
| 847 if (Verbose) { | |
| 848 gclog_or_tty->print(" "SIZE_FORMAT"("SIZE_FORMAT")", | |
| 849 gch->used(), gch->capacity()); | |
| 850 } else { | |
| 851 gclog_or_tty->print(" "SIZE_FORMAT"K("SIZE_FORMAT"K)", | |
| 852 gch->used() / K, gch->capacity() / K); | |
| 853 } | |
| 854 } | |
| 855 | |
| 856 size_t | |
| 857 ConcurrentMarkSweepGeneration::contiguous_available() const { | |
| 858 // dld proposes an improvement in precision here. If the committed | |
| 859 // part of the space ends in a free block we should add that to | |
| 860 // uncommitted size in the calculation below. Will make this | |
| 861 // change later, staying with the approximation below for the | |
| 862 // time being. -- ysr. | |
| 863 return MAX2(_virtual_space.uncommitted_size(), unsafe_max_alloc_nogc()); | |
| 864 } | |
| 865 | |
| 866 size_t | |
| 867 ConcurrentMarkSweepGeneration::unsafe_max_alloc_nogc() const { | |
| 868 return _cmsSpace->max_alloc_in_words() * HeapWordSize; | |
| 869 } | |
| 870 | |
| 871 size_t ConcurrentMarkSweepGeneration::max_available() const { | |
| 872 return free() + _virtual_space.uncommitted_size(); | |
| 873 } | |
| 874 | |
|
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875 bool ConcurrentMarkSweepGeneration::promotion_attempt_is_safe(size_t max_promotion_in_bytes) const { |
|
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876 size_t available = max_available(); |
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877 size_t av_promo = (size_t)gc_stats()->avg_promoted()->padded_average(); |
|
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878 bool res = (available >= av_promo) || (available >= max_promotion_in_bytes); |
|
1994
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879 if (Verbose && PrintGCDetails) { |
|
1888
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880 gclog_or_tty->print_cr( |
|
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881 "CMS: promo attempt is%s safe: available("SIZE_FORMAT") %s av_promo("SIZE_FORMAT")," |
|
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882 "max_promo("SIZE_FORMAT")", |
|
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883 res? "":" not", available, res? ">=":"<", |
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884 av_promo, max_promotion_in_bytes); |
|
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885 } |
|
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|
886 return res; |
| 0 | 887 } |
| 888 | |
|
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889 // At a promotion failure dump information on block layout in heap |
|
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|
890 // (cms old generation). |
|
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|
891 void ConcurrentMarkSweepGeneration::promotion_failure_occurred() { |
|
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|
892 if (CMSDumpAtPromotionFailure) { |
|
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6631166: CMS: better heuristics when combatting fragmentation
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|
893 cmsSpace()->dump_at_safepoint_with_locks(collector(), gclog_or_tty); |
|
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|
894 } |
|
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|
895 } |
|
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|
896 |
| 0 | 897 CompactibleSpace* |
| 898 ConcurrentMarkSweepGeneration::first_compaction_space() const { | |
| 899 return _cmsSpace; | |
| 900 } | |
| 901 | |
| 902 void ConcurrentMarkSweepGeneration::reset_after_compaction() { | |
| 903 // Clear the promotion information. These pointers can be adjusted | |
| 904 // along with all the other pointers into the heap but | |
| 905 // compaction is expected to be a rare event with | |
| 906 // 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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|
907 if (CollectedHeap::use_parallel_gc_threads()) { |
| 0 | 908 for (uint i = 0; i < ParallelGCThreads; i++) { |
| 909 _par_gc_thread_states[i]->promo.reset(); | |
| 910 } | |
| 911 } | |
| 912 } | |
| 913 | |
| 914 void ConcurrentMarkSweepGeneration::space_iterate(SpaceClosure* blk, bool usedOnly) { | |
| 915 blk->do_space(_cmsSpace); | |
| 916 } | |
| 917 | |
| 918 void ConcurrentMarkSweepGeneration::compute_new_size() { | |
| 919 assert_locked_or_safepoint(Heap_lock); | |
| 920 | |
| 921 // If incremental collection failed, we just want to expand | |
| 922 // to the limit. | |
| 923 if (incremental_collection_failed()) { | |
| 924 clear_incremental_collection_failed(); | |
| 925 grow_to_reserved(); | |
| 926 return; | |
| 927 } | |
| 928 | |
|
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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929 // The heap has been compacted but not reset yet. |
|
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930 // Any metric such as free() or used() will be incorrect. |
|
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931 |
|
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|
932 CardGeneration::compute_new_size(); |
|
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933 |
|
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|
934 // Reset again after a possible resizing |
|
10244
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8013184: CMS: Call reset_after_compaction() only if a compaction has been done
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|
935 if (did_compact()) { |
|
06ab37f08701
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|
936 cmsSpace()->reset_after_compaction(); |
|
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937 } |
|
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938 } |
|
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939 |
|
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940 void ConcurrentMarkSweepGeneration::compute_new_size_free_list() { |
|
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941 assert_locked_or_safepoint(Heap_lock); |
|
8617e38bb4cb
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942 |
|
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943 // If incremental collection failed, we just want to expand |
|
8617e38bb4cb
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944 // to the limit. |
|
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|
945 if (incremental_collection_failed()) { |
|
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946 clear_incremental_collection_failed(); |
|
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|
947 grow_to_reserved(); |
|
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|
948 return; |
|
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|
949 } |
|
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|
950 |
| 0 | 951 double free_percentage = ((double) free()) / capacity(); |
| 952 double desired_free_percentage = (double) MinHeapFreeRatio / 100; | |
| 953 double maximum_free_percentage = (double) MaxHeapFreeRatio / 100; | |
| 954 | |
| 955 // compute expansion delta needed for reaching desired free percentage | |
| 956 if (free_percentage < desired_free_percentage) { | |
| 957 size_t desired_capacity = (size_t)(used() / ((double) 1 - desired_free_percentage)); | |
| 958 assert(desired_capacity >= capacity(), "invalid expansion size"); | |
|
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959 size_t expand_bytes = MAX2(desired_capacity - capacity(), MinHeapDeltaBytes); |
| 0 | 960 if (PrintGCDetails && Verbose) { |
| 961 size_t desired_capacity = (size_t)(used() / ((double) 1 - desired_free_percentage)); | |
| 962 gclog_or_tty->print_cr("\nFrom compute_new_size: "); | |
| 963 gclog_or_tty->print_cr(" Free fraction %f", free_percentage); | |
| 964 gclog_or_tty->print_cr(" Desired free fraction %f", | |
| 965 desired_free_percentage); | |
| 966 gclog_or_tty->print_cr(" Maximum free fraction %f", | |
| 967 maximum_free_percentage); | |
| 968 gclog_or_tty->print_cr(" Capactiy "SIZE_FORMAT, capacity()/1000); | |
| 969 gclog_or_tty->print_cr(" Desired capacity "SIZE_FORMAT, | |
| 970 desired_capacity/1000); | |
| 971 int prev_level = level() - 1; | |
| 972 if (prev_level >= 0) { | |
| 973 size_t prev_size = 0; | |
| 974 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 975 Generation* prev_gen = gch->_gens[prev_level]; | |
| 976 prev_size = prev_gen->capacity(); | |
| 977 gclog_or_tty->print_cr(" Younger gen size "SIZE_FORMAT, | |
| 978 prev_size/1000); | |
| 979 } | |
| 980 gclog_or_tty->print_cr(" unsafe_max_alloc_nogc "SIZE_FORMAT, | |
| 981 unsafe_max_alloc_nogc()/1000); | |
| 982 gclog_or_tty->print_cr(" contiguous available "SIZE_FORMAT, | |
| 983 contiguous_available()/1000); | |
| 984 gclog_or_tty->print_cr(" Expand by "SIZE_FORMAT" (bytes)", | |
| 985 expand_bytes); | |
| 986 } | |
| 987 // safe if expansion fails | |
| 988 expand(expand_bytes, 0, CMSExpansionCause::_satisfy_free_ratio); | |
| 989 if (PrintGCDetails && Verbose) { | |
| 990 gclog_or_tty->print_cr(" Expanded free fraction %f", | |
| 991 ((double) free()) / capacity()); | |
| 992 } | |
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993 } else { |
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994 size_t desired_capacity = (size_t)(used() / ((double) 1 - desired_free_percentage)); |
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995 assert(desired_capacity <= capacity(), "invalid expansion size"); |
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996 size_t shrink_bytes = capacity() - desired_capacity; |
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997 // Don't shrink unless the delta is greater than the minimum shrink we want |
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998 if (shrink_bytes >= MinHeapDeltaBytes) { |
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999 shrink_free_list_by(shrink_bytes); |
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1000 } |
| 0 | 1001 } |
| 1002 } | |
| 1003 | |
| 1004 Mutex* ConcurrentMarkSweepGeneration::freelistLock() const { | |
| 1005 return cmsSpace()->freelistLock(); | |
| 1006 } | |
| 1007 | |
| 1008 HeapWord* ConcurrentMarkSweepGeneration::allocate(size_t size, | |
| 1009 bool tlab) { | |
| 1010 CMSSynchronousYieldRequest yr; | |
| 1011 MutexLockerEx x(freelistLock(), | |
| 1012 Mutex::_no_safepoint_check_flag); | |
| 1013 return have_lock_and_allocate(size, tlab); | |
| 1014 } | |
| 1015 | |
| 1016 HeapWord* ConcurrentMarkSweepGeneration::have_lock_and_allocate(size_t size, | |
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1017 bool tlab /* ignored */) { |
| 0 | 1018 assert_lock_strong(freelistLock()); |
| 1019 size_t adjustedSize = CompactibleFreeListSpace::adjustObjectSize(size); | |
| 1020 HeapWord* res = cmsSpace()->allocate(adjustedSize); | |
| 1021 // Allocate the object live (grey) if the background collector has | |
| 1022 // started marking. This is necessary because the marker may | |
| 1023 // have passed this address and consequently this object will | |
| 1024 // not otherwise be greyed and would be incorrectly swept up. | |
| 1025 // Note that if this object contains references, the writing | |
| 1026 // of those references will dirty the card containing this object | |
| 1027 // allowing the object to be blackened (and its references scanned) | |
| 1028 // either during a preclean phase or at the final checkpoint. | |
| 1029 if (res != NULL) { | |
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1030 // We may block here with an uninitialized object with |
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1031 // its mark-bit or P-bits not yet set. Such objects need |
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1032 // to be safely navigable by block_start(). |
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1033 assert(oop(res)->klass_or_null() == NULL, "Object should be uninitialized here."); |
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1034 assert(!((FreeChunk*)res)->is_free(), "Error, block will look free but show wrong size"); |
| 0 | 1035 collector()->direct_allocated(res, adjustedSize); |
| 1036 _direct_allocated_words += adjustedSize; | |
| 1037 // allocation counters | |
| 1038 NOT_PRODUCT( | |
| 1039 _numObjectsAllocated++; | |
| 1040 _numWordsAllocated += (int)adjustedSize; | |
| 1041 ) | |
| 1042 } | |
| 1043 return res; | |
| 1044 } | |
| 1045 | |
| 1046 // In the case of direct allocation by mutators in a generation that | |
| 1047 // is being concurrently collected, the object must be allocated | |
| 1048 // live (grey) if the background collector has started marking. | |
| 1049 // This is necessary because the marker may | |
| 1050 // have passed this address and consequently this object will | |
| 1051 // not otherwise be greyed and would be incorrectly swept up. | |
| 1052 // Note that if this object contains references, the writing | |
| 1053 // of those references will dirty the card containing this object | |
| 1054 // allowing the object to be blackened (and its references scanned) | |
| 1055 // either during a preclean phase or at the final checkpoint. | |
| 1056 void CMSCollector::direct_allocated(HeapWord* start, size_t size) { | |
| 1057 assert(_markBitMap.covers(start, size), "Out of bounds"); | |
| 1058 if (_collectorState >= Marking) { | |
| 1059 MutexLockerEx y(_markBitMap.lock(), | |
| 1060 Mutex::_no_safepoint_check_flag); | |
| 1061 // [see comments preceding SweepClosure::do_blk() below for details] | |
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1062 // |
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1063 // Can the P-bits be deleted now? JJJ |
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1064 // |
| 0 | 1065 // 1. need to mark the object as live so it isn't collected |
| 1066 // 2. need to mark the 2nd bit to indicate the object may be uninitialized | |
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1067 // 3. need to mark the end of the object so marking, precleaning or sweeping |
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1068 // can skip over uninitialized or unparsable objects. An allocated |
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1069 // object is considered uninitialized for our purposes as long as |
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1070 // its klass word is NULL. All old gen objects are parsable |
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1071 // as soon as they are initialized.) |
| 0 | 1072 _markBitMap.mark(start); // object is live |
| 1073 _markBitMap.mark(start + 1); // object is potentially uninitialized? | |
| 1074 _markBitMap.mark(start + size - 1); | |
| 1075 // mark end of object | |
| 1076 } | |
| 1077 // check that oop looks uninitialized | |
| 187 | 1078 assert(oop(start)->klass_or_null() == NULL, "_klass should be NULL"); |
| 0 | 1079 } |
| 1080 | |
| 1081 void CMSCollector::promoted(bool par, HeapWord* start, | |
| 1082 bool is_obj_array, size_t obj_size) { | |
| 1083 assert(_markBitMap.covers(start), "Out of bounds"); | |
| 1084 // See comment in direct_allocated() about when objects should | |
| 1085 // be allocated live. | |
| 1086 if (_collectorState >= Marking) { | |
| 1087 // we already hold the marking bit map lock, taken in | |
| 1088 // the prologue | |
| 1089 if (par) { | |
| 1090 _markBitMap.par_mark(start); | |
| 1091 } else { | |
| 1092 _markBitMap.mark(start); | |
| 1093 } | |
| 1094 // We don't need to mark the object as uninitialized (as | |
| 1095 // in direct_allocated above) because this is being done with the | |
| 1096 // world stopped and the object will be initialized by the | |
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1097 // time the marking, precleaning or sweeping get to look at it. |
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1098 // But see the code for copying objects into the CMS generation, |
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1099 // where we need to ensure that concurrent readers of the |
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1100 // block offset table are able to safely navigate a block that |
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1101 // is in flux from being free to being allocated (and in |
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1102 // transition while being copied into) and subsequently |
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1103 // becoming a bona-fide object when the copy/promotion is complete. |
| 0 | 1104 assert(SafepointSynchronize::is_at_safepoint(), |
| 1105 "expect promotion only at safepoints"); | |
| 1106 | |
| 1107 if (_collectorState < Sweeping) { | |
| 1108 // Mark the appropriate cards in the modUnionTable, so that | |
| 1109 // this object gets scanned before the sweep. If this is | |
| 1110 // not done, CMS generation references in the object might | |
| 1111 // not get marked. | |
| 1112 // For the case of arrays, which are otherwise precisely | |
| 1113 // marked, we need to dirty the entire array, not just its head. | |
| 1114 if (is_obj_array) { | |
| 1115 // The [par_]mark_range() method expects mr.end() below to | |
| 1116 // be aligned to the granularity of a bit's representation | |
| 1117 // in the heap. In the case of the MUT below, that's a | |
| 1118 // card size. | |
| 1119 MemRegion mr(start, | |
| 1120 (HeapWord*)round_to((intptr_t)(start + obj_size), | |
| 1121 CardTableModRefBS::card_size /* bytes */)); | |
| 1122 if (par) { | |
| 1123 _modUnionTable.par_mark_range(mr); | |
| 1124 } else { | |
| 1125 _modUnionTable.mark_range(mr); | |
| 1126 } | |
| 1127 } else { // not an obj array; we can just mark the head | |
| 1128 if (par) { | |
| 1129 _modUnionTable.par_mark(start); | |
| 1130 } else { | |
| 1131 _modUnionTable.mark(start); | |
| 1132 } | |
| 1133 } | |
| 1134 } | |
| 1135 } | |
| 1136 } | |
| 1137 | |
| 1138 static inline size_t percent_of_space(Space* space, HeapWord* addr) | |
| 1139 { | |
| 1140 size_t delta = pointer_delta(addr, space->bottom()); | |
| 1141 return (size_t)(delta * 100.0 / (space->capacity() / HeapWordSize)); | |
| 1142 } | |
| 1143 | |
| 1144 void CMSCollector::icms_update_allocation_limits() | |
| 1145 { | |
| 1146 Generation* gen0 = GenCollectedHeap::heap()->get_gen(0); | |
| 1147 EdenSpace* eden = gen0->as_DefNewGeneration()->eden(); | |
| 1148 | |
| 1149 const unsigned int duty_cycle = stats().icms_update_duty_cycle(); | |
| 1150 if (CMSTraceIncrementalPacing) { | |
| 1151 stats().print(); | |
| 1152 } | |
| 1153 | |
| 1154 assert(duty_cycle <= 100, "invalid duty cycle"); | |
| 1155 if (duty_cycle != 0) { | |
| 1156 // The duty_cycle is a percentage between 0 and 100; convert to words and | |
| 1157 // then compute the offset from the endpoints of the space. | |
| 1158 size_t free_words = eden->free() / HeapWordSize; | |
| 1159 double free_words_dbl = (double)free_words; | |
| 1160 size_t duty_cycle_words = (size_t)(free_words_dbl * duty_cycle / 100.0); | |
| 1161 size_t offset_words = (free_words - duty_cycle_words) / 2; | |
| 1162 | |
| 1163 _icms_start_limit = eden->top() + offset_words; | |
| 1164 _icms_stop_limit = eden->end() - offset_words; | |
| 1165 | |
| 1166 // The limits may be adjusted (shifted to the right) by | |
| 1167 // CMSIncrementalOffset, to allow the application more mutator time after a | |
| 1168 // young gen gc (when all mutators were stopped) and before CMS starts and | |
| 1169 // takes away one or more cpus. | |
| 1170 if (CMSIncrementalOffset != 0) { | |
| 1171 double adjustment_dbl = free_words_dbl * CMSIncrementalOffset / 100.0; | |
| 1172 size_t adjustment = (size_t)adjustment_dbl; | |
| 1173 HeapWord* tmp_stop = _icms_stop_limit + adjustment; | |
| 1174 if (tmp_stop > _icms_stop_limit && tmp_stop < eden->end()) { | |
| 1175 _icms_start_limit += adjustment; | |
| 1176 _icms_stop_limit = tmp_stop; | |
| 1177 } | |
| 1178 } | |
| 1179 } | |
| 1180 if (duty_cycle == 0 || (_icms_start_limit == _icms_stop_limit)) { | |
| 1181 _icms_start_limit = _icms_stop_limit = eden->end(); | |
| 1182 } | |
| 1183 | |
| 1184 // Install the new start limit. | |
| 1185 eden->set_soft_end(_icms_start_limit); | |
| 1186 | |
| 1187 if (CMSTraceIncrementalMode) { | |
| 1188 gclog_or_tty->print(" icms alloc limits: " | |
| 1189 PTR_FORMAT "," PTR_FORMAT | |
| 1190 " (" SIZE_FORMAT "%%," SIZE_FORMAT "%%) ", | |
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1191 p2i(_icms_start_limit), p2i(_icms_stop_limit), |
| 0 | 1192 percent_of_space(eden, _icms_start_limit), |
| 1193 percent_of_space(eden, _icms_stop_limit)); | |
| 1194 if (Verbose) { | |
| 1195 gclog_or_tty->print("eden: "); | |
| 1196 eden->print_on(gclog_or_tty); | |
| 1197 } | |
| 1198 } | |
| 1199 } | |
| 1200 | |
| 1201 // Any changes here should try to maintain the invariant | |
| 1202 // that if this method is called with _icms_start_limit | |
| 1203 // and _icms_stop_limit both NULL, then it should return NULL | |
| 1204 // and not notify the icms thread. | |
| 1205 HeapWord* | |
| 1206 CMSCollector::allocation_limit_reached(Space* space, HeapWord* top, | |
| 1207 size_t word_size) | |
| 1208 { | |
| 1209 // A start_limit equal to end() means the duty cycle is 0, so treat that as a | |
| 1210 // nop. | |
| 1211 if (CMSIncrementalMode && _icms_start_limit != space->end()) { | |
| 1212 if (top <= _icms_start_limit) { | |
| 1213 if (CMSTraceIncrementalMode) { | |
| 1214 space->print_on(gclog_or_tty); | |
| 1215 gclog_or_tty->stamp(); | |
| 1216 gclog_or_tty->print_cr(" start limit top=" PTR_FORMAT | |
| 1217 ", new limit=" PTR_FORMAT | |
| 1218 " (" SIZE_FORMAT "%%)", | |
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1219 p2i(top), p2i(_icms_stop_limit), |
| 0 | 1220 percent_of_space(space, _icms_stop_limit)); |
| 1221 } | |
| 1222 ConcurrentMarkSweepThread::start_icms(); | |
| 1223 assert(top < _icms_stop_limit, "Tautology"); | |
| 1224 if (word_size < pointer_delta(_icms_stop_limit, top)) { | |
| 1225 return _icms_stop_limit; | |
| 1226 } | |
| 1227 | |
| 1228 // The allocation will cross both the _start and _stop limits, so do the | |
| 1229 // stop notification also and return end(). | |
| 1230 if (CMSTraceIncrementalMode) { | |
| 1231 space->print_on(gclog_or_tty); | |
| 1232 gclog_or_tty->stamp(); | |
| 1233 gclog_or_tty->print_cr(" +stop limit top=" PTR_FORMAT | |
| 1234 ", new limit=" PTR_FORMAT | |
| 1235 " (" SIZE_FORMAT "%%)", | |
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1236 p2i(top), p2i(space->end()), |
| 0 | 1237 percent_of_space(space, space->end())); |
| 1238 } | |
| 1239 ConcurrentMarkSweepThread::stop_icms(); | |
| 1240 return space->end(); | |
| 1241 } | |
| 1242 | |
| 1243 if (top <= _icms_stop_limit) { | |
| 1244 if (CMSTraceIncrementalMode) { | |
| 1245 space->print_on(gclog_or_tty); | |
| 1246 gclog_or_tty->stamp(); | |
| 1247 gclog_or_tty->print_cr(" stop limit top=" PTR_FORMAT | |
| 1248 ", new limit=" PTR_FORMAT | |
| 1249 " (" SIZE_FORMAT "%%)", | |
| 1250 top, space->end(), | |
| 1251 percent_of_space(space, space->end())); | |
| 1252 } | |
| 1253 ConcurrentMarkSweepThread::stop_icms(); | |
| 1254 return space->end(); | |
| 1255 } | |
| 1256 | |
| 1257 if (CMSTraceIncrementalMode) { | |
| 1258 space->print_on(gclog_or_tty); | |
| 1259 gclog_or_tty->stamp(); | |
| 1260 gclog_or_tty->print_cr(" end limit top=" PTR_FORMAT | |
| 1261 ", new limit=" PTR_FORMAT, | |
| 1262 top, NULL); | |
| 1263 } | |
| 1264 } | |
| 1265 | |
| 1266 return NULL; | |
| 1267 } | |
| 1268 | |
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1269 oop ConcurrentMarkSweepGeneration::promote(oop obj, size_t obj_size) { |
| 0 | 1270 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in"); |
| 1271 // allocate, copy and if necessary update promoinfo -- | |
| 1272 // delegate to underlying space. | |
| 1273 assert_lock_strong(freelistLock()); | |
| 1274 | |
| 1275 #ifndef PRODUCT | |
| 1276 if (Universe::heap()->promotion_should_fail()) { | |
| 1277 return NULL; | |
| 1278 } | |
| 1279 #endif // #ifndef PRODUCT | |
| 1280 | |
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1281 oop res = _cmsSpace->promote(obj, obj_size); |
| 0 | 1282 if (res == NULL) { |
| 1283 // expand and retry | |
| 1284 size_t s = _cmsSpace->expansionSpaceRequired(obj_size); // HeapWords | |
| 1285 expand(s*HeapWordSize, MinHeapDeltaBytes, | |
| 1286 CMSExpansionCause::_satisfy_promotion); | |
| 1287 // Since there's currently no next generation, we don't try to promote | |
| 1288 // into a more senior generation. | |
| 1289 assert(next_gen() == NULL, "assumption, based upon which no attempt " | |
| 1290 "is made to pass on a possibly failing " | |
| 1291 "promotion to next generation"); | |
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1292 res = _cmsSpace->promote(obj, obj_size); |
| 0 | 1293 } |
| 1294 if (res != NULL) { | |
| 1295 // See comment in allocate() about when objects should | |
| 1296 // be allocated live. | |
| 1297 assert(obj->is_oop(), "Will dereference klass pointer below"); | |
| 1298 collector()->promoted(false, // Not parallel | |
| 1299 (HeapWord*)res, obj->is_objArray(), obj_size); | |
| 1300 // promotion counters | |
| 1301 NOT_PRODUCT( | |
| 1302 _numObjectsPromoted++; | |
| 1303 _numWordsPromoted += | |
| 1304 (int)(CompactibleFreeListSpace::adjustObjectSize(obj->size())); | |
| 1305 ) | |
| 1306 } | |
| 1307 return res; | |
| 1308 } | |
| 1309 | |
| 1310 | |
| 1311 HeapWord* | |
| 1312 ConcurrentMarkSweepGeneration::allocation_limit_reached(Space* space, | |
| 1313 HeapWord* top, | |
| 1314 size_t word_sz) | |
| 1315 { | |
| 1316 return collector()->allocation_limit_reached(space, top, word_sz); | |
| 1317 } | |
| 1318 | |
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1319 // IMPORTANT: Notes on object size recognition in CMS. |
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1320 // --------------------------------------------------- |
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1321 // A block of storage in the CMS generation is always in |
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1322 // one of three states. A free block (FREE), an allocated |
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1323 // object (OBJECT) whose size() method reports the correct size, |
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1324 // and an intermediate state (TRANSIENT) in which its size cannot |
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1325 // be accurately determined. |
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1326 // STATE IDENTIFICATION: (32 bit and 64 bit w/o COOPS) |
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1327 // ----------------------------------------------------- |
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1328 // FREE: klass_word & 1 == 1; mark_word holds block size |
|
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1329 // |
|
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1330 // OBJECT: klass_word installed; klass_word != 0 && klass_word & 1 == 0; |
|
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1331 // obj->size() computes correct size |
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1332 // |
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1333 // TRANSIENT: klass_word == 0; size is indeterminate until we become an OBJECT |
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1334 // |
|
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1335 // STATE IDENTIFICATION: (64 bit+COOPS) |
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1336 // ------------------------------------ |
|
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1337 // FREE: mark_word & CMS_FREE_BIT == 1; mark_word & ~CMS_FREE_BIT gives block_size |
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1338 // |
|
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1339 // OBJECT: klass_word installed; klass_word != 0; |
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1340 // obj->size() computes correct size |
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1341 // |
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1342 // TRANSIENT: klass_word == 0; size is indeterminate until we become an OBJECT |
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1343 // |
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1344 // |
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1345 // STATE TRANSITION DIAGRAM |
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1346 // |
|
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1347 // mut / parnew mut / parnew |
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1348 // FREE --------------------> TRANSIENT ---------------------> OBJECT --| |
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1349 // ^ | |
|
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1350 // |------------------------ DEAD <------------------------------------| |
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1351 // sweep mut |
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1352 // |
|
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1353 // While a block is in TRANSIENT state its size cannot be determined |
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1354 // so readers will either need to come back later or stall until |
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1355 // the size can be determined. Note that for the case of direct |
|
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1356 // allocation, P-bits, when available, may be used to determine the |
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1357 // size of an object that may not yet have been initialized. |
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1358 |
| 0 | 1359 // Things to support parallel young-gen collection. |
| 1360 oop | |
| 1361 ConcurrentMarkSweepGeneration::par_promote(int thread_num, | |
| 1362 oop old, markOop m, | |
| 1363 size_t word_sz) { | |
| 1364 #ifndef PRODUCT | |
| 1365 if (Universe::heap()->promotion_should_fail()) { | |
| 1366 return NULL; | |
| 1367 } | |
| 1368 #endif // #ifndef PRODUCT | |
| 1369 | |
| 1370 CMSParGCThreadState* ps = _par_gc_thread_states[thread_num]; | |
| 1371 PromotionInfo* promoInfo = &ps->promo; | |
| 1372 // if we are tracking promotions, then first ensure space for | |
| 1373 // promotion (including spooling space for saving header if necessary). | |
| 1374 // then allocate and copy, then track promoted info if needed. | |
| 1375 // When tracking (see PromotionInfo::track()), the mark word may | |
| 1376 // be displaced and in this case restoration of the mark word | |
| 1377 // occurs in the (oop_since_save_marks_)iterate phase. | |
| 1378 if (promoInfo->tracking() && !promoInfo->ensure_spooling_space()) { | |
| 1379 // Out of space for allocating spooling buffers; | |
| 1380 // try expanding and allocating spooling buffers. | |
| 1381 if (!expand_and_ensure_spooling_space(promoInfo)) { | |
| 1382 return NULL; | |
| 1383 } | |
| 1384 } | |
| 1385 assert(promoInfo->has_spooling_space(), "Control point invariant"); | |
|
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1386 const size_t alloc_sz = CompactibleFreeListSpace::adjustObjectSize(word_sz); |
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1387 HeapWord* obj_ptr = ps->lab.alloc(alloc_sz); |
| 0 | 1388 if (obj_ptr == NULL) { |
|
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1389 obj_ptr = expand_and_par_lab_allocate(ps, alloc_sz); |
| 0 | 1390 if (obj_ptr == NULL) { |
| 1391 return NULL; | |
| 1392 } | |
| 1393 } | |
| 1394 oop obj = oop(obj_ptr); | |
|
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1395 OrderAccess::storestore(); |
| 187 | 1396 assert(obj->klass_or_null() == NULL, "Object should be uninitialized here."); |
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1397 assert(!((FreeChunk*)obj_ptr)->is_free(), "Error, block will look free but show wrong size"); |
|
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1398 // IMPORTANT: See note on object initialization for CMS above. |
| 0 | 1399 // Otherwise, copy the object. Here we must be careful to insert the |
| 1400 // klass pointer last, since this marks the block as an allocated object. | |
| 187 | 1401 // Except with compressed oops it's the mark word. |
| 0 | 1402 HeapWord* old_ptr = (HeapWord*)old; |
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1403 // Restore the mark word copied above. |
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1404 obj->set_mark(m); |
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1405 assert(obj->klass_or_null() == NULL, "Object should be uninitialized here."); |
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1406 assert(!((FreeChunk*)obj_ptr)->is_free(), "Error, block will look free but show wrong size"); |
|
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1407 OrderAccess::storestore(); |
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1408 |
|
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1409 if (UseCompressedClassPointers) { |
|
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1410 // Copy gap missed by (aligned) header size calculation below |
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1411 obj->set_klass_gap(old->klass_gap()); |
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1412 } |
| 0 | 1413 if (word_sz > (size_t)oopDesc::header_size()) { |
| 1414 Copy::aligned_disjoint_words(old_ptr + oopDesc::header_size(), | |
| 1415 obj_ptr + oopDesc::header_size(), | |
| 1416 word_sz - oopDesc::header_size()); | |
| 1417 } | |
| 187 | 1418 |
| 0 | 1419 // Now we can track the promoted object, if necessary. We take care |
| 1521 | 1420 // to delay the transition from uninitialized to full object |
| 0 | 1421 // (i.e., insertion of klass pointer) until after, so that it |
| 1422 // atomically becomes a promoted object. | |
| 1423 if (promoInfo->tracking()) { | |
| 1424 promoInfo->track((PromotedObject*)obj, old->klass()); | |
| 1425 } | |
|
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1426 assert(obj->klass_or_null() == NULL, "Object should be uninitialized here."); |
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1427 assert(!((FreeChunk*)obj_ptr)->is_free(), "Error, block will look free but show wrong size"); |
|
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1428 assert(old->is_oop(), "Will use and dereference old klass ptr below"); |
| 187 | 1429 |
| 1430 // Finally, install the klass pointer (this should be volatile). | |
|
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1431 OrderAccess::storestore(); |
| 0 | 1432 obj->set_klass(old->klass()); |
|
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1433 // We should now be able to calculate the right size for this object |
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1434 assert(obj->is_oop() && obj->size() == (int)word_sz, "Error, incorrect size computed for promoted object"); |
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1435 |
| 0 | 1436 collector()->promoted(true, // parallel |
| 1437 obj_ptr, old->is_objArray(), word_sz); | |
| 1438 | |
| 1439 NOT_PRODUCT( | |
|
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1440 Atomic::inc_ptr(&_numObjectsPromoted); |
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1441 Atomic::add_ptr(alloc_sz, &_numWordsPromoted); |
| 0 | 1442 ) |
| 1443 | |
| 1444 return obj; | |
| 1445 } | |
| 1446 | |
| 1447 void | |
| 1448 ConcurrentMarkSweepGeneration:: | |
| 1449 par_promote_alloc_undo(int thread_num, | |
| 1450 HeapWord* obj, size_t word_sz) { | |
| 1451 // CMS does not support promotion undo. | |
| 1452 ShouldNotReachHere(); | |
| 1453 } | |
| 1454 | |
| 1455 void | |
| 1456 ConcurrentMarkSweepGeneration:: | |
| 1457 par_promote_alloc_done(int thread_num) { | |
| 1458 CMSParGCThreadState* ps = _par_gc_thread_states[thread_num]; | |
|
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1459 ps->lab.retire(thread_num); |
| 0 | 1460 } |
| 1461 | |
| 1462 void | |
| 1463 ConcurrentMarkSweepGeneration:: | |
| 1464 par_oop_since_save_marks_iterate_done(int thread_num) { | |
| 1465 CMSParGCThreadState* ps = _par_gc_thread_states[thread_num]; | |
| 1466 ParScanWithoutBarrierClosure* dummy_cl = NULL; | |
| 1467 ps->promo.promoted_oops_iterate_nv(dummy_cl); | |
| 1468 } | |
| 1469 | |
| 1470 bool ConcurrentMarkSweepGeneration::should_collect(bool full, | |
| 1471 size_t size, | |
| 1472 bool tlab) | |
| 1473 { | |
| 1474 // We allow a STW collection only if a full | |
| 1475 // collection was requested. | |
| 1476 return full || should_allocate(size, tlab); // FIX ME !!! | |
| 1477 // This and promotion failure handling are connected at the | |
| 1478 // hip and should be fixed by untying them. | |
| 1479 } | |
| 1480 | |
| 1481 bool CMSCollector::shouldConcurrentCollect() { | |
| 1482 if (_full_gc_requested) { | |
| 1483 if (Verbose && PrintGCDetails) { | |
| 1484 gclog_or_tty->print_cr("CMSCollector: collect because of explicit " | |
|
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1485 " gc request (or gc_locker)"); |
| 0 | 1486 } |
| 1487 return true; | |
| 1488 } | |
| 1489 | |
| 1490 // For debugging purposes, change the type of collection. | |
| 1491 // If the rotation is not on the concurrent collection | |
| 1492 // type, don't start a concurrent collection. | |
| 1493 NOT_PRODUCT( | |
| 1494 if (RotateCMSCollectionTypes && | |
| 1495 (_cmsGen->debug_collection_type() != | |
| 1496 ConcurrentMarkSweepGeneration::Concurrent_collection_type)) { | |
| 1497 assert(_cmsGen->debug_collection_type() != | |
| 1498 ConcurrentMarkSweepGeneration::Unknown_collection_type, | |
| 1499 "Bad cms collection type"); | |
| 1500 return false; | |
| 1501 } | |
| 1502 ) | |
| 1503 | |
| 1504 FreelistLocker x(this); | |
| 1505 // ------------------------------------------------------------------ | |
| 1506 // Print out lots of information which affects the initiation of | |
| 1507 // a collection. | |
| 1508 if (PrintCMSInitiationStatistics && stats().valid()) { | |
| 1509 gclog_or_tty->print("CMSCollector shouldConcurrentCollect: "); | |
| 1510 gclog_or_tty->stamp(); | |
|
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1511 gclog_or_tty->cr(); |
| 0 | 1512 stats().print_on(gclog_or_tty); |
| 1513 gclog_or_tty->print_cr("time_until_cms_gen_full %3.7f", | |
| 1514 stats().time_until_cms_gen_full()); | |
| 1515 gclog_or_tty->print_cr("free="SIZE_FORMAT, _cmsGen->free()); | |
| 1516 gclog_or_tty->print_cr("contiguous_available="SIZE_FORMAT, | |
| 1517 _cmsGen->contiguous_available()); | |
| 1518 gclog_or_tty->print_cr("promotion_rate=%g", stats().promotion_rate()); | |
| 1519 gclog_or_tty->print_cr("cms_allocation_rate=%g", stats().cms_allocation_rate()); | |
| 1520 gclog_or_tty->print_cr("occupancy=%3.7f", _cmsGen->occupancy()); | |
|
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1521 gclog_or_tty->print_cr("initiatingOccupancy=%3.7f", _cmsGen->initiating_occupancy()); |
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1522 gclog_or_tty->print_cr("metadata initialized %d", |
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1523 MetaspaceGC::should_concurrent_collect()); |
| 0 | 1524 } |
| 1525 // ------------------------------------------------------------------ | |
| 1526 | |
| 1527 // If the estimated time to complete a cms collection (cms_duration()) | |
| 1528 // is less than the estimated time remaining until the cms generation | |
| 1529 // is full, start a collection. | |
| 1530 if (!UseCMSInitiatingOccupancyOnly) { | |
| 1531 if (stats().valid()) { | |
| 1532 if (stats().time_until_cms_start() == 0.0) { | |
| 1533 return true; | |
| 1534 } | |
| 1535 } else { | |
| 1536 // We want to conservatively collect somewhat early in order | |
| 1537 // to try and "bootstrap" our CMS/promotion statistics; | |
| 1538 // this branch will not fire after the first successful CMS | |
| 1539 // collection because the stats should then be valid. | |
| 1540 if (_cmsGen->occupancy() >= _bootstrap_occupancy) { | |
| 1541 if (Verbose && PrintGCDetails) { | |
| 1542 gclog_or_tty->print_cr( | |
| 1543 " CMSCollector: collect for bootstrapping statistics:" | |
| 1544 " occupancy = %f, boot occupancy = %f", _cmsGen->occupancy(), | |
| 1545 _bootstrap_occupancy); | |
| 1546 } | |
| 1547 return true; | |
| 1548 } | |
| 1549 } | |
| 1550 } | |
| 1551 | |
|
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1552 // Otherwise, we start a collection cycle if |
| 0 | 1553 // old gen want a collection cycle started. Each may use |
| 1554 // an appropriate criterion for making this decision. | |
| 1555 // XXX We need to make sure that the gen expansion | |
|
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1556 // criterion dovetails well with this. XXX NEED TO FIX THIS |
|
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1557 if (_cmsGen->should_concurrent_collect()) { |
| 0 | 1558 if (Verbose && PrintGCDetails) { |
| 1559 gclog_or_tty->print_cr("CMS old gen initiated"); | |
| 1560 } | |
| 1561 return true; | |
| 1562 } | |
| 1563 | |
|
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1564 // We start a collection if we believe an incremental collection may fail; |
|
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1565 // this is not likely to be productive in practice because it's probably too |
|
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1566 // late anyway. |
|
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1567 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
|
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1568 assert(gch->collector_policy()->is_two_generation_policy(), |
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1569 "You may want to check the correctness of the following"); |
|
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1570 if (gch->incremental_collection_will_fail(true /* consult_young */)) { |
|
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1571 if (Verbose && PrintGCDetails) { |
|
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1572 gclog_or_tty->print("CMSCollector: collect because incremental collection will fail "); |
| 0 | 1573 } |
| 1574 return true; | |
| 1575 } | |
| 1576 | |
|
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1577 if (MetaspaceGC::should_concurrent_collect()) { |
|
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1578 if (Verbose && PrintGCDetails) { |
|
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1579 gclog_or_tty->print("CMSCollector: collect for metadata allocation "); |
|
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1580 } |
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1581 return true; |
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1582 } |
|
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1583 |
| 0 | 1584 return false; |
| 1585 } | |
| 1586 | |
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1587 void CMSCollector::set_did_compact(bool v) { _cmsGen->set_did_compact(v); } |
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1588 |
| 0 | 1589 // Clear _expansion_cause fields of constituent generations |
| 1590 void CMSCollector::clear_expansion_cause() { | |
| 1591 _cmsGen->clear_expansion_cause(); | |
| 1592 } | |
| 1593 | |
|
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1594 // We should be conservative in starting a collection cycle. To |
|
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1595 // start too eagerly runs the risk of collecting too often in the |
|
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1596 // extreme. To collect too rarely falls back on full collections, |
|
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1597 // which works, even if not optimum in terms of concurrent work. |
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1598 // As a work around for too eagerly collecting, use the flag |
|
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1599 // UseCMSInitiatingOccupancyOnly. This also has the advantage of |
|
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1600 // giving the user an easily understandable way of controlling the |
|
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1601 // collections. |
|
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1602 // We want to start a new collection cycle if any of the following |
|
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1603 // conditions hold: |
|
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1604 // . our current occupancy exceeds the configured initiating occupancy |
|
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1605 // for this generation, or |
|
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1606 // . we recently needed to expand this space and have not, since that |
|
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1607 // expansion, done a collection of this generation, or |
|
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1608 // . the underlying space believes that it may be a good idea to initiate |
|
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1609 // a concurrent collection (this may be based on criteria such as the |
|
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1610 // following: the space uses linear allocation and linear allocation is |
|
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1611 // going to fail, or there is believed to be excessive fragmentation in |
|
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1612 // the generation, etc... or ... |
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1613 // [.(currently done by CMSCollector::shouldConcurrentCollect() only for |
|
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1614 // the case of the old generation; see CR 6543076): |
|
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1615 // we may be approaching a point at which allocation requests may fail because |
|
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1616 // we will be out of sufficient free space given allocation rate estimates.] |
|
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1617 bool ConcurrentMarkSweepGeneration::should_concurrent_collect() const { |
|
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1618 |
| 0 | 1619 assert_lock_strong(freelistLock()); |
|
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1620 if (occupancy() > initiating_occupancy()) { |
| 0 | 1621 if (PrintGCDetails && Verbose) { |
| 1622 gclog_or_tty->print(" %s: collect because of occupancy %f / %f ", | |
|
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1623 short_name(), occupancy(), initiating_occupancy()); |
| 0 | 1624 } |
| 1625 return true; | |
| 1626 } | |
| 1627 if (UseCMSInitiatingOccupancyOnly) { | |
| 1628 return false; | |
| 1629 } | |
| 1630 if (expansion_cause() == CMSExpansionCause::_satisfy_allocation) { | |
| 1631 if (PrintGCDetails && Verbose) { | |
| 1632 gclog_or_tty->print(" %s: collect because expanded for allocation ", | |
| 1633 short_name()); | |
| 1634 } | |
| 1635 return true; | |
| 1636 } | |
|
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1637 if (_cmsSpace->should_concurrent_collect()) { |
| 0 | 1638 if (PrintGCDetails && Verbose) { |
|
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1639 gclog_or_tty->print(" %s: collect because cmsSpace says so ", |
| 0 | 1640 short_name()); |
| 1641 } | |
| 1642 return true; | |
| 1643 } | |
| 1644 return false; | |
| 1645 } | |
| 1646 | |
| 1647 void ConcurrentMarkSweepGeneration::collect(bool full, | |
| 1648 bool clear_all_soft_refs, | |
| 1649 size_t size, | |
| 1650 bool tlab) | |
| 1651 { | |
| 1652 collector()->collect(full, clear_all_soft_refs, size, tlab); | |
| 1653 } | |
| 1654 | |
| 1655 void CMSCollector::collect(bool full, | |
| 1656 bool clear_all_soft_refs, | |
| 1657 size_t size, | |
| 1658 bool tlab) | |
| 1659 { | |
| 1660 if (!UseCMSCollectionPassing && _collectorState > Idling) { | |
| 1661 // For debugging purposes skip the collection if the state | |
| 1662 // is not currently idle | |
| 1663 if (TraceCMSState) { | |
| 1664 gclog_or_tty->print_cr("Thread " INTPTR_FORMAT " skipped full:%d CMS state %d", | |
| 1665 Thread::current(), full, _collectorState); | |
| 1666 } | |
| 1667 return; | |
| 1668 } | |
| 1669 | |
| 1670 // The following "if" branch is present for defensive reasons. | |
| 1671 // In the current uses of this interface, it can be replaced with: | |
| 1672 // assert(!GC_locker.is_active(), "Can't be called otherwise"); | |
| 1673 // But I am not placing that assert here to allow future | |
| 1674 // generality in invoking this interface. | |
| 1675 if (GC_locker::is_active()) { | |
| 1676 // A consistency test for GC_locker | |
| 1677 assert(GC_locker::needs_gc(), "Should have been set already"); | |
| 1678 // Skip this foreground collection, instead | |
| 1679 // expanding the heap if necessary. | |
| 1680 // Need the free list locks for the call to free() in compute_new_size() | |
| 1681 compute_new_size(); | |
| 1682 return; | |
| 1683 } | |
| 1684 acquire_control_and_collect(full, clear_all_soft_refs); | |
| 1685 _full_gcs_since_conc_gc++; | |
| 1686 } | |
| 1687 | |
| 10405 | 1688 void CMSCollector::request_full_gc(unsigned int full_gc_count, GCCause::Cause cause) { |
| 0 | 1689 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
| 1690 unsigned int gc_count = gch->total_full_collections(); | |
| 1691 if (gc_count == full_gc_count) { | |
| 1692 MutexLockerEx y(CGC_lock, Mutex::_no_safepoint_check_flag); | |
| 1693 _full_gc_requested = true; | |
| 10405 | 1694 _full_gc_cause = cause; |
| 0 | 1695 CGC_lock->notify(); // nudge CMS thread |
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1696 } else { |
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1697 assert(gc_count > full_gc_count, "Error: causal loop"); |
| 0 | 1698 } |
| 1699 } | |
| 1700 | |
| 10405 | 1701 bool CMSCollector::is_external_interruption() { |
| 1702 GCCause::Cause cause = GenCollectedHeap::heap()->gc_cause(); | |
| 1703 return GCCause::is_user_requested_gc(cause) || | |
| 1704 GCCause::is_serviceability_requested_gc(cause); | |
| 1705 } | |
| 1706 | |
| 1707 void CMSCollector::report_concurrent_mode_interruption() { | |
| 1708 if (is_external_interruption()) { | |
| 1709 if (PrintGCDetails) { | |
| 1710 gclog_or_tty->print(" (concurrent mode interrupted)"); | |
| 1711 } | |
| 1712 } else { | |
| 1713 if (PrintGCDetails) { | |
| 1714 gclog_or_tty->print(" (concurrent mode failure)"); | |
| 1715 } | |
| 1716 _gc_tracer_cm->report_concurrent_mode_failure(); | |
| 1717 } | |
| 1718 } | |
| 1719 | |
| 0 | 1720 |
| 1721 // The foreground and background collectors need to coordinate in order | |
| 1722 // to make sure that they do not mutually interfere with CMS collections. | |
| 1723 // When a background collection is active, | |
| 1724 // the foreground collector may need to take over (preempt) and | |
| 1725 // synchronously complete an ongoing collection. Depending on the | |
| 1726 // frequency of the background collections and the heap usage | |
| 1727 // of the application, this preemption can be seldom or frequent. | |
| 1728 // There are only certain | |
| 1729 // points in the background collection that the "collection-baton" | |
| 1730 // can be passed to the foreground collector. | |
| 1731 // | |
| 1732 // The foreground collector will wait for the baton before | |
| 1733 // starting any part of the collection. The foreground collector | |
| 1734 // will only wait at one location. | |
| 1735 // | |
| 1736 // The background collector will yield the baton before starting a new | |
| 1737 // phase of the collection (e.g., before initial marking, marking from roots, | |
| 1738 // precleaning, final re-mark, sweep etc.) This is normally done at the head | |
| 1739 // of the loop which switches the phases. The background collector does some | |
| 1740 // of the phases (initial mark, final re-mark) with the world stopped. | |
| 1741 // Because of locking involved in stopping the world, | |
| 1742 // the foreground collector should not block waiting for the background | |
| 1743 // collector when it is doing a stop-the-world phase. The background | |
| 1744 // collector will yield the baton at an additional point just before | |
| 1745 // it enters a stop-the-world phase. Once the world is stopped, the | |
| 1746 // background collector checks the phase of the collection. If the | |
| 1747 // phase has not changed, it proceeds with the collection. If the | |
| 1748 // phase has changed, it skips that phase of the collection. See | |
| 1749 // the comments on the use of the Heap_lock in collect_in_background(). | |
| 1750 // | |
| 1751 // Variable used in baton passing. | |
| 1752 // _foregroundGCIsActive - Set to true by the foreground collector when | |
| 1753 // it wants the baton. The foreground clears it when it has finished | |
| 1754 // the collection. | |
| 1755 // _foregroundGCShouldWait - Set to true by the background collector | |
| 1756 // when it is running. The foreground collector waits while | |
| 1757 // _foregroundGCShouldWait is true. | |
| 1758 // CGC_lock - monitor used to protect access to the above variables | |
| 1759 // and to notify the foreground and background collectors. | |
| 1760 // _collectorState - current state of the CMS collection. | |
| 1761 // | |
| 1762 // The foreground collector | |
| 1763 // acquires the CGC_lock | |
| 1764 // sets _foregroundGCIsActive | |
| 1765 // waits on the CGC_lock for _foregroundGCShouldWait to be false | |
| 1766 // various locks acquired in preparation for the collection | |
| 1767 // are released so as not to block the background collector | |
| 1768 // that is in the midst of a collection | |
| 1769 // proceeds with the collection | |
| 1770 // clears _foregroundGCIsActive | |
| 1771 // returns | |
| 1772 // | |
| 1773 // The background collector in a loop iterating on the phases of the | |
| 1774 // collection | |
| 1775 // acquires the CGC_lock | |
| 1776 // sets _foregroundGCShouldWait | |
| 1777 // if _foregroundGCIsActive is set | |
| 1778 // clears _foregroundGCShouldWait, notifies _CGC_lock | |
| 1779 // waits on _CGC_lock for _foregroundGCIsActive to become false | |
| 1780 // and exits the loop. | |
| 1781 // otherwise | |
| 1782 // proceed with that phase of the collection | |
| 1783 // if the phase is a stop-the-world phase, | |
| 1784 // yield the baton once more just before enqueueing | |
| 1785 // the stop-world CMS operation (executed by the VM thread). | |
| 1786 // returns after all phases of the collection are done | |
| 1787 // | |
| 1788 | |
| 1789 void CMSCollector::acquire_control_and_collect(bool full, | |
| 1790 bool clear_all_soft_refs) { | |
| 1791 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); | |
| 1792 assert(!Thread::current()->is_ConcurrentGC_thread(), | |
| 1793 "shouldn't try to acquire control from self!"); | |
| 1794 | |
| 1795 // Start the protocol for acquiring control of the | |
| 1796 // collection from the background collector (aka CMS thread). | |
| 1797 assert(ConcurrentMarkSweepThread::vm_thread_has_cms_token(), | |
| 1798 "VM thread should have CMS token"); | |
| 1799 // Remember the possibly interrupted state of an ongoing | |
| 1800 // concurrent collection | |
| 1801 CollectorState first_state = _collectorState; | |
| 1802 | |
| 1803 // Signal to a possibly ongoing concurrent collection that | |
| 1804 // we want to do a foreground collection. | |
| 1805 _foregroundGCIsActive = true; | |
| 1806 | |
| 1807 // Disable incremental mode during a foreground collection. | |
| 1808 ICMSDisabler icms_disabler; | |
| 1809 | |
| 1810 // release locks and wait for a notify from the background collector | |
| 1811 // releasing the locks in only necessary for phases which | |
| 1812 // do yields to improve the granularity of the collection. | |
| 1813 assert_lock_strong(bitMapLock()); | |
| 1814 // We need to lock the Free list lock for the space that we are | |
| 1815 // currently collecting. | |
| 1816 assert(haveFreelistLocks(), "Must be holding free list locks"); | |
| 1817 bitMapLock()->unlock(); | |
| 1818 releaseFreelistLocks(); | |
| 1819 { | |
| 1820 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
| 1821 if (_foregroundGCShouldWait) { | |
| 1822 // We are going to be waiting for action for the CMS thread; | |
| 1823 // it had better not be gone (for instance at shutdown)! | |
| 1824 assert(ConcurrentMarkSweepThread::cmst() != NULL, | |
| 1825 "CMS thread must be running"); | |
| 1826 // Wait here until the background collector gives us the go-ahead | |
| 1827 ConcurrentMarkSweepThread::clear_CMS_flag( | |
| 1828 ConcurrentMarkSweepThread::CMS_vm_has_token); // release token | |
| 1829 // Get a possibly blocked CMS thread going: | |
| 1830 // Note that we set _foregroundGCIsActive true above, | |
| 1831 // without protection of the CGC_lock. | |
| 1832 CGC_lock->notify(); | |
| 1833 assert(!ConcurrentMarkSweepThread::vm_thread_wants_cms_token(), | |
| 1834 "Possible deadlock"); | |
| 1835 while (_foregroundGCShouldWait) { | |
| 1836 // wait for notification | |
| 1837 CGC_lock->wait(Mutex::_no_safepoint_check_flag); | |
| 1838 // Possibility of delay/starvation here, since CMS token does | |
| 1839 // not know to give priority to VM thread? Actually, i think | |
| 1840 // there wouldn't be any delay/starvation, but the proof of | |
| 1841 // that "fact" (?) appears non-trivial. XXX 20011219YSR | |
| 1842 } | |
| 1843 ConcurrentMarkSweepThread::set_CMS_flag( | |
| 1844 ConcurrentMarkSweepThread::CMS_vm_has_token); | |
| 1845 } | |
| 1846 } | |
| 1847 // The CMS_token is already held. Get back the other locks. | |
| 1848 assert(ConcurrentMarkSweepThread::vm_thread_has_cms_token(), | |
| 1849 "VM thread should have CMS token"); | |
| 1850 getFreelistLocks(); | |
| 1851 bitMapLock()->lock_without_safepoint_check(); | |
| 1852 if (TraceCMSState) { | |
| 1853 gclog_or_tty->print_cr("CMS foreground collector has asked for control " | |
| 1854 INTPTR_FORMAT " with first state %d", Thread::current(), first_state); | |
| 1855 gclog_or_tty->print_cr(" gets control with state %d", _collectorState); | |
| 1856 } | |
| 1857 | |
| 1858 // Check if we need to do a compaction, or if not, whether | |
| 1859 // we need to start the mark-sweep from scratch. | |
| 1860 bool should_compact = false; | |
| 1861 bool should_start_over = false; | |
| 1862 decide_foreground_collection_type(clear_all_soft_refs, | |
| 1863 &should_compact, &should_start_over); | |
| 1864 | |
| 1865 NOT_PRODUCT( | |
| 1866 if (RotateCMSCollectionTypes) { | |
| 1867 if (_cmsGen->debug_collection_type() == | |
| 1868 ConcurrentMarkSweepGeneration::MSC_foreground_collection_type) { | |
| 1869 should_compact = true; | |
| 1870 } else if (_cmsGen->debug_collection_type() == | |
| 1871 ConcurrentMarkSweepGeneration::MS_foreground_collection_type) { | |
| 1872 should_compact = false; | |
| 1873 } | |
| 1874 } | |
| 1875 ) | |
| 1876 | |
| 10405 | 1877 if (first_state > Idling) { |
| 1878 report_concurrent_mode_interruption(); | |
| 0 | 1879 } |
| 1880 | |
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1881 set_did_compact(should_compact); |
| 0 | 1882 if (should_compact) { |
| 1883 // If the collection is being acquired from the background | |
| 1884 // collector, there may be references on the discovered | |
| 1885 // references lists that have NULL referents (being those | |
| 1886 // that were concurrently cleared by a mutator) or | |
| 1887 // that are no longer active (having been enqueued concurrently | |
| 1888 // by the mutator). | |
| 1889 // Scrub the list of those references because Mark-Sweep-Compact | |
| 1890 // code assumes referents are not NULL and that all discovered | |
| 1891 // Reference objects are active. | |
| 1892 ref_processor()->clean_up_discovered_references(); | |
| 1893 | |
| 10405 | 1894 if (first_state > Idling) { |
| 1895 save_heap_summary(); | |
| 1896 } | |
| 1897 | |
| 0 | 1898 do_compaction_work(clear_all_soft_refs); |
| 1899 | |
| 1900 // Has the GC time limit been exceeded? | |
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1901 DefNewGeneration* young_gen = _young_gen->as_DefNewGeneration(); |
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1902 size_t max_eden_size = young_gen->max_capacity() - |
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1903 young_gen->to()->capacity() - |
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1904 young_gen->from()->capacity(); |
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1905 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
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1906 GCCause::Cause gc_cause = gch->gc_cause(); |
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1907 size_policy()->check_gc_overhead_limit(_young_gen->used(), |
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1908 young_gen->eden()->used(), |
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1909 _cmsGen->max_capacity(), |
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1910 max_eden_size, |
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1911 full, |
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1912 gc_cause, |
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1913 gch->collector_policy()); |
| 0 | 1914 } else { |
| 1915 do_mark_sweep_work(clear_all_soft_refs, first_state, | |
| 1916 should_start_over); | |
| 1917 } | |
| 1918 // Reset the expansion cause, now that we just completed | |
| 1919 // a collection cycle. | |
| 1920 clear_expansion_cause(); | |
| 1921 _foregroundGCIsActive = false; | |
| 1922 return; | |
| 1923 } | |
| 1924 | |
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1925 // Resize the tenured generation |
| 0 | 1926 // after obtaining the free list locks for the |
| 1927 // two generations. | |
| 1928 void CMSCollector::compute_new_size() { | |
| 1929 assert_locked_or_safepoint(Heap_lock); | |
| 1930 FreelistLocker z(this); | |
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1931 MetaspaceGC::compute_new_size(); |
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1932 _cmsGen->compute_new_size_free_list(); |
| 0 | 1933 } |
| 1934 | |
| 1935 // A work method used by foreground collection to determine | |
| 1936 // what type of collection (compacting or not, continuing or fresh) | |
| 1937 // it should do. | |
| 1938 // NOTE: the intent is to make UseCMSCompactAtFullCollection | |
| 1939 // and CMSCompactWhenClearAllSoftRefs the default in the future | |
| 1940 // and do away with the flags after a suitable period. | |
| 1941 void CMSCollector::decide_foreground_collection_type( | |
| 1942 bool clear_all_soft_refs, bool* should_compact, | |
| 1943 bool* should_start_over) { | |
| 1944 // Normally, we'll compact only if the UseCMSCompactAtFullCollection | |
| 1945 // flag is set, and we have either requested a System.gc() or | |
| 1946 // the number of full gc's since the last concurrent cycle | |
| 1947 // has exceeded the threshold set by CMSFullGCsBeforeCompaction, | |
| 1948 // or if an incremental collection has failed | |
| 1949 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 1950 assert(gch->collector_policy()->is_two_generation_policy(), | |
| 1951 "You may want to check the correctness of the following"); | |
| 1952 // Inform cms gen if this was due to partial collection failing. | |
| 1953 // The CMS gen may use this fact to determine its expansion policy. | |
|
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1954 if (gch->incremental_collection_will_fail(false /* don't consult_young */)) { |
| 0 | 1955 assert(!_cmsGen->incremental_collection_failed(), |
| 1956 "Should have been noticed, reacted to and cleared"); | |
| 1957 _cmsGen->set_incremental_collection_failed(); | |
| 1958 } | |
| 1959 *should_compact = | |
| 1960 UseCMSCompactAtFullCollection && | |
| 1961 ((_full_gcs_since_conc_gc >= CMSFullGCsBeforeCompaction) || | |
| 1962 GCCause::is_user_requested_gc(gch->gc_cause()) || | |
|
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1963 gch->incremental_collection_will_fail(true /* consult_young */)); |
| 0 | 1964 *should_start_over = false; |
| 1965 if (clear_all_soft_refs && !*should_compact) { | |
| 1966 // We are about to do a last ditch collection attempt | |
| 1967 // so it would normally make sense to do a compaction | |
| 1968 // to reclaim as much space as possible. | |
| 1969 if (CMSCompactWhenClearAllSoftRefs) { | |
| 1970 // Default: The rationale is that in this case either | |
| 1971 // we are past the final marking phase, in which case | |
| 1972 // we'd have to start over, or so little has been done | |
| 1973 // that there's little point in saving that work. Compaction | |
| 1974 // appears to be the sensible choice in either case. | |
| 1975 *should_compact = true; | |
| 1976 } else { | |
| 1977 // We have been asked to clear all soft refs, but not to | |
| 1978 // compact. Make sure that we aren't past the final checkpoint | |
| 1979 // phase, for that is where we process soft refs. If we are already | |
| 1980 // past that phase, we'll need to redo the refs discovery phase and | |
| 1981 // if necessary clear soft refs that weren't previously | |
| 1982 // cleared. We do so by remembering the phase in which | |
| 1983 // we came in, and if we are past the refs processing | |
| 1984 // phase, we'll choose to just redo the mark-sweep | |
| 1985 // collection from scratch. | |
| 1986 if (_collectorState > FinalMarking) { | |
| 1987 // We are past the refs processing phase; | |
| 1988 // start over and do a fresh synchronous CMS cycle | |
| 1989 _collectorState = Resetting; // skip to reset to start new cycle | |
| 1990 reset(false /* == !asynch */); | |
| 1991 *should_start_over = true; | |
| 1992 } // else we can continue a possibly ongoing current cycle | |
| 1993 } | |
| 1994 } | |
| 1995 } | |
| 1996 | |
| 1997 // A work method used by the foreground collector to do | |
| 1998 // a mark-sweep-compact. | |
| 1999 void CMSCollector::do_compaction_work(bool clear_all_soft_refs) { | |
| 2000 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 10405 | 2001 |
| 2002 STWGCTimer* gc_timer = GenMarkSweep::gc_timer(); | |
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2003 gc_timer->register_gc_start(); |
| 10405 | 2004 |
| 2005 SerialOldTracer* gc_tracer = GenMarkSweep::gc_tracer(); | |
| 2006 gc_tracer->report_gc_start(gch->gc_cause(), gc_timer->gc_start()); | |
| 2007 | |
| 2008 GCTraceTime t("CMS:MSC ", PrintGCDetails && Verbose, true, NULL); | |
| 0 | 2009 if (PrintGC && Verbose && !(GCCause::is_user_requested_gc(gch->gc_cause()))) { |
| 2010 gclog_or_tty->print_cr("Compact ConcurrentMarkSweepGeneration after %d " | |
| 2011 "collections passed to foreground collector", _full_gcs_since_conc_gc); | |
| 2012 } | |
| 2013 | |
| 2014 // Sample collection interval time and reset for collection pause. | |
| 2015 if (UseAdaptiveSizePolicy) { | |
| 2016 size_policy()->msc_collection_begin(); | |
| 2017 } | |
| 2018 | |
| 2019 // Temporarily widen the span of the weak reference processing to | |
| 2020 // the entire heap. | |
| 2021 MemRegion new_span(GenCollectedHeap::heap()->reserved_region()); | |
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2022 ReferenceProcessorSpanMutator rp_mut_span(ref_processor(), new_span); |
| 0 | 2023 // Temporarily, clear the "is_alive_non_header" field of the |
| 2024 // reference processor. | |
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2025 ReferenceProcessorIsAliveMutator rp_mut_closure(ref_processor(), NULL); |
| 0 | 2026 // Temporarily make reference _processing_ single threaded (non-MT). |
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2027 ReferenceProcessorMTProcMutator rp_mut_mt_processing(ref_processor(), false); |
| 0 | 2028 // Temporarily make refs discovery atomic |
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2029 ReferenceProcessorAtomicMutator rp_mut_atomic(ref_processor(), true); |
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2030 // Temporarily make reference _discovery_ single threaded (non-MT) |
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2031 ReferenceProcessorMTDiscoveryMutator rp_mut_discovery(ref_processor(), false); |
| 0 | 2032 |
| 2033 ref_processor()->set_enqueuing_is_done(false); | |
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2034 ref_processor()->enable_discovery(false /*verify_disabled*/, false /*check_no_refs*/); |
|
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2035 ref_processor()->setup_policy(clear_all_soft_refs); |
| 0 | 2036 // If an asynchronous collection finishes, the _modUnionTable is |
| 2037 // all clear. If we are assuming the collection from an asynchronous | |
| 2038 // collection, clear the _modUnionTable. | |
| 2039 assert(_collectorState != Idling || _modUnionTable.isAllClear(), | |
| 2040 "_modUnionTable should be clear if the baton was not passed"); | |
| 2041 _modUnionTable.clear_all(); | |
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2042 assert(_collectorState != Idling || _ct->klass_rem_set()->mod_union_is_clear(), |
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2043 "mod union for klasses should be clear if the baton was passed"); |
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2044 _ct->klass_rem_set()->clear_mod_union(); |
| 0 | 2045 |
| 2046 // We must adjust the allocation statistics being maintained | |
| 2047 // in the free list space. We do so by reading and clearing | |
| 2048 // the sweep timer and updating the block flux rate estimates below. | |
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2049 assert(!_intra_sweep_timer.is_active(), "_intra_sweep_timer should be inactive"); |
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2050 if (_inter_sweep_timer.is_active()) { |
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2051 _inter_sweep_timer.stop(); |
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2052 // Note that we do not use this sample to update the _inter_sweep_estimate. |
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2053 _cmsGen->cmsSpace()->beginSweepFLCensus((float)(_inter_sweep_timer.seconds()), |
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2054 _inter_sweep_estimate.padded_average(), |
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2055 _intra_sweep_estimate.padded_average()); |
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2056 } |
| 0 | 2057 |
| 2058 GenMarkSweep::invoke_at_safepoint(_cmsGen->level(), | |
| 2059 ref_processor(), clear_all_soft_refs); | |
| 2060 #ifdef ASSERT | |
| 2061 CompactibleFreeListSpace* cms_space = _cmsGen->cmsSpace(); | |
| 2062 size_t free_size = cms_space->free(); | |
| 2063 assert(free_size == | |
| 2064 pointer_delta(cms_space->end(), cms_space->compaction_top()) | |
| 2065 * HeapWordSize, | |
| 2066 "All the free space should be compacted into one chunk at top"); | |
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2067 assert(cms_space->dictionary()->total_chunk_size( |
| 0 | 2068 debug_only(cms_space->freelistLock())) == 0 || |
| 2069 cms_space->totalSizeInIndexedFreeLists() == 0, | |
| 2070 "All the free space should be in a single chunk"); | |
| 2071 size_t num = cms_space->totalCount(); | |
| 2072 assert((free_size == 0 && num == 0) || | |
| 2073 (free_size > 0 && (num == 1 || num == 2)), | |
| 2074 "There should be at most 2 free chunks after compaction"); | |
| 2075 #endif // ASSERT | |
| 2076 _collectorState = Resetting; | |
| 2077 assert(_restart_addr == NULL, | |
| 2078 "Should have been NULL'd before baton was passed"); | |
| 2079 reset(false /* == !asynch */); | |
| 2080 _cmsGen->reset_after_compaction(); | |
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2081 _concurrent_cycles_since_last_unload = 0; |
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2082 |
| 0 | 2083 // Clear any data recorded in the PLAB chunk arrays. |
| 2084 if (_survivor_plab_array != NULL) { | |
| 2085 reset_survivor_plab_arrays(); | |
| 2086 } | |
| 2087 | |
| 2088 // Adjust the per-size allocation stats for the next epoch. | |
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2089 _cmsGen->cmsSpace()->endSweepFLCensus(sweep_count() /* fake */); |
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2090 // Restart the "inter sweep timer" for the next epoch. |
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2091 _inter_sweep_timer.reset(); |
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2092 _inter_sweep_timer.start(); |
| 0 | 2093 |
| 2094 // Sample collection pause time and reset for collection interval. | |
| 2095 if (UseAdaptiveSizePolicy) { | |
| 2096 size_policy()->msc_collection_end(gch->gc_cause()); | |
| 2097 } | |
| 2098 | |
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2099 gc_timer->register_gc_end(); |
| 10405 | 2100 |
| 2101 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); | |
| 2102 | |
| 0 | 2103 // For a mark-sweep-compact, compute_new_size() will be called |
| 2104 // in the heap's do_collection() method. | |
| 2105 } | |
| 2106 | |
| 2107 // A work method used by the foreground collector to do | |
| 2108 // a mark-sweep, after taking over from a possibly on-going | |
| 2109 // concurrent mark-sweep collection. | |
| 2110 void CMSCollector::do_mark_sweep_work(bool clear_all_soft_refs, | |
| 2111 CollectorState first_state, bool should_start_over) { | |
| 2112 if (PrintGC && Verbose) { | |
| 2113 gclog_or_tty->print_cr("Pass concurrent collection to foreground " | |
| 2114 "collector with count %d", | |
| 2115 _full_gcs_since_conc_gc); | |
| 2116 } | |
| 2117 switch (_collectorState) { | |
| 2118 case Idling: | |
| 2119 if (first_state == Idling || should_start_over) { | |
| 2120 // The background GC was not active, or should | |
| 2121 // restarted from scratch; start the cycle. | |
| 2122 _collectorState = InitialMarking; | |
| 2123 } | |
| 2124 // If first_state was not Idling, then a background GC | |
| 2125 // was in progress and has now finished. No need to do it | |
| 2126 // again. Leave the state as Idling. | |
| 2127 break; | |
| 2128 case Precleaning: | |
| 2129 // In the foreground case don't do the precleaning since | |
| 2130 // it is not done concurrently and there is extra work | |
| 2131 // required. | |
| 2132 _collectorState = FinalMarking; | |
| 2133 } | |
| 10405 | 2134 collect_in_foreground(clear_all_soft_refs, GenCollectedHeap::heap()->gc_cause()); |
| 0 | 2135 |
| 2136 // For a mark-sweep, compute_new_size() will be called | |
| 2137 // in the heap's do_collection() method. | |
| 2138 } | |
| 2139 | |
| 2140 | |
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2141 void CMSCollector::print_eden_and_survivor_chunk_arrays() { |
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2142 DefNewGeneration* dng = _young_gen->as_DefNewGeneration(); |
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2143 EdenSpace* eden_space = dng->eden(); |
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2144 ContiguousSpace* from_space = dng->from(); |
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2145 ContiguousSpace* to_space = dng->to(); |
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2146 // Eden |
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2147 if (_eden_chunk_array != NULL) { |
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2148 gclog_or_tty->print_cr("eden " PTR_FORMAT "-" PTR_FORMAT "-" PTR_FORMAT "(" SIZE_FORMAT ")", |
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2149 eden_space->bottom(), eden_space->top(), |
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2150 eden_space->end(), eden_space->capacity()); |
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2151 gclog_or_tty->print_cr("_eden_chunk_index=" SIZE_FORMAT ", " |
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2152 "_eden_chunk_capacity=" SIZE_FORMAT, |
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2153 _eden_chunk_index, _eden_chunk_capacity); |
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2154 for (size_t i = 0; i < _eden_chunk_index; i++) { |
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2155 gclog_or_tty->print_cr("_eden_chunk_array[" SIZE_FORMAT "]=" PTR_FORMAT, |
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2156 i, _eden_chunk_array[i]); |
|
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2157 } |
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2158 } |
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2159 // Survivor |
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2160 if (_survivor_chunk_array != NULL) { |
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2161 gclog_or_tty->print_cr("survivor " PTR_FORMAT "-" PTR_FORMAT "-" PTR_FORMAT "(" SIZE_FORMAT ")", |
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2162 from_space->bottom(), from_space->top(), |
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2163 from_space->end(), from_space->capacity()); |
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2164 gclog_or_tty->print_cr("_survivor_chunk_index=" SIZE_FORMAT ", " |
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2165 "_survivor_chunk_capacity=" SIZE_FORMAT, |
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2166 _survivor_chunk_index, _survivor_chunk_capacity); |
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2167 for (size_t i = 0; i < _survivor_chunk_index; i++) { |
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2168 gclog_or_tty->print_cr("_survivor_chunk_array[" SIZE_FORMAT "]=" PTR_FORMAT, |
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2169 i, _survivor_chunk_array[i]); |
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2170 } |
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2171 } |
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2172 } |
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2173 |
| 0 | 2174 void CMSCollector::getFreelistLocks() const { |
| 2175 // Get locks for all free lists in all generations that this | |
| 2176 // collector is responsible for | |
| 2177 _cmsGen->freelistLock()->lock_without_safepoint_check(); | |
| 2178 } | |
| 2179 | |
| 2180 void CMSCollector::releaseFreelistLocks() const { | |
| 2181 // Release locks for all free lists in all generations that this | |
| 2182 // collector is responsible for | |
| 2183 _cmsGen->freelistLock()->unlock(); | |
| 2184 } | |
| 2185 | |
| 2186 bool CMSCollector::haveFreelistLocks() const { | |
| 2187 // Check locks for all free lists in all generations that this | |
| 2188 // collector is responsible for | |
| 2189 assert_lock_strong(_cmsGen->freelistLock()); | |
| 2190 PRODUCT_ONLY(ShouldNotReachHere()); | |
| 2191 return true; | |
| 2192 } | |
| 2193 | |
| 2194 // A utility class that is used by the CMS collector to | |
| 2195 // temporarily "release" the foreground collector from its | |
| 2196 // usual obligation to wait for the background collector to | |
| 2197 // complete an ongoing phase before proceeding. | |
| 2198 class ReleaseForegroundGC: public StackObj { | |
| 2199 private: | |
| 2200 CMSCollector* _c; | |
| 2201 public: | |
| 2202 ReleaseForegroundGC(CMSCollector* c) : _c(c) { | |
| 2203 assert(_c->_foregroundGCShouldWait, "Else should not need to call"); | |
| 2204 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
| 2205 // allow a potentially blocked foreground collector to proceed | |
| 2206 _c->_foregroundGCShouldWait = false; | |
| 2207 if (_c->_foregroundGCIsActive) { | |
| 2208 CGC_lock->notify(); | |
| 2209 } | |
| 2210 assert(!ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 2211 "Possible deadlock"); | |
| 2212 } | |
| 2213 | |
| 2214 ~ReleaseForegroundGC() { | |
| 2215 assert(!_c->_foregroundGCShouldWait, "Usage protocol violation?"); | |
| 2216 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
| 2217 _c->_foregroundGCShouldWait = true; | |
| 2218 } | |
| 2219 }; | |
| 2220 | |
| 2221 // There are separate collect_in_background and collect_in_foreground because of | |
| 2222 // the different locking requirements of the background collector and the | |
| 2223 // foreground collector. There was originally an attempt to share | |
| 2224 // one "collect" method between the background collector and the foreground | |
| 2225 // collector but the if-then-else required made it cleaner to have | |
| 2226 // separate methods. | |
| 10405 | 2227 void CMSCollector::collect_in_background(bool clear_all_soft_refs, GCCause::Cause cause) { |
| 0 | 2228 assert(Thread::current()->is_ConcurrentGC_thread(), |
| 2229 "A CMS asynchronous collection is only allowed on a CMS thread."); | |
| 2230 | |
| 2231 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 2232 { | |
| 2233 bool safepoint_check = Mutex::_no_safepoint_check_flag; | |
| 2234 MutexLockerEx hl(Heap_lock, safepoint_check); | |
|
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2235 FreelistLocker fll(this); |
| 0 | 2236 MutexLockerEx x(CGC_lock, safepoint_check); |
| 2237 if (_foregroundGCIsActive || !UseAsyncConcMarkSweepGC) { | |
| 2238 // The foreground collector is active or we're | |
| 2239 // not using asynchronous collections. Skip this | |
| 2240 // background collection. | |
| 2241 assert(!_foregroundGCShouldWait, "Should be clear"); | |
| 2242 return; | |
| 2243 } else { | |
| 2244 assert(_collectorState == Idling, "Should be idling before start."); | |
| 2245 _collectorState = InitialMarking; | |
| 10405 | 2246 register_gc_start(cause); |
| 0 | 2247 // Reset the expansion cause, now that we are about to begin |
| 2248 // a new cycle. | |
| 2249 clear_expansion_cause(); | |
|
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2250 |
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2251 // Clear the MetaspaceGC flag since a concurrent collection |
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2252 // is starting but also clear it after the collection. |
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2253 MetaspaceGC::set_should_concurrent_collect(false); |
| 0 | 2254 } |
|
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2255 // Decide if we want to enable class unloading as part of the |
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2256 // ensuing concurrent GC cycle. |
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2257 update_should_unload_classes(); |
| 0 | 2258 _full_gc_requested = false; // acks all outstanding full gc requests |
| 10405 | 2259 _full_gc_cause = GCCause::_no_gc; |
| 0 | 2260 // Signal that we are about to start a collection |
| 2261 gch->increment_total_full_collections(); // ... starting a collection cycle | |
| 2262 _collection_count_start = gch->total_full_collections(); | |
| 2263 } | |
| 2264 | |
| 2265 // Used for PrintGC | |
| 2266 size_t prev_used; | |
| 2267 if (PrintGC && Verbose) { | |
| 2268 prev_used = _cmsGen->used(); // XXXPERM | |
| 2269 } | |
| 2270 | |
| 2271 // The change of the collection state is normally done at this level; | |
| 2272 // the exceptions are phases that are executed while the world is | |
| 2273 // stopped. For those phases the change of state is done while the | |
| 2274 // world is stopped. For baton passing purposes this allows the | |
| 2275 // background collector to finish the phase and change state atomically. | |
| 2276 // The foreground collector cannot wait on a phase that is done | |
| 2277 // while the world is stopped because the foreground collector already | |
| 2278 // has the world stopped and would deadlock. | |
| 2279 while (_collectorState != Idling) { | |
| 2280 if (TraceCMSState) { | |
| 2281 gclog_or_tty->print_cr("Thread " INTPTR_FORMAT " in CMS state %d", | |
| 2282 Thread::current(), _collectorState); | |
| 2283 } | |
| 2284 // The foreground collector | |
| 2285 // holds the Heap_lock throughout its collection. | |
| 2286 // holds the CMS token (but not the lock) | |
| 2287 // except while it is waiting for the background collector to yield. | |
| 2288 // | |
| 2289 // The foreground collector should be blocked (not for long) | |
| 2290 // if the background collector is about to start a phase | |
| 2291 // executed with world stopped. If the background | |
| 2292 // collector has already started such a phase, the | |
| 2293 // foreground collector is blocked waiting for the | |
| 2294 // Heap_lock. The stop-world phases (InitialMarking and FinalMarking) | |
| 2295 // are executed in the VM thread. | |
| 2296 // | |
| 2297 // The locking order is | |
| 2298 // PendingListLock (PLL) -- if applicable (FinalMarking) | |
| 2299 // Heap_lock (both this & PLL locked in VM_CMS_Operation::prologue()) | |
| 2300 // CMS token (claimed in | |
| 2301 // stop_world_and_do() --> | |
| 2302 // safepoint_synchronize() --> | |
| 2303 // CMSThread::synchronize()) | |
| 2304 | |
| 2305 { | |
| 2306 // Check if the FG collector wants us to yield. | |
| 2307 CMSTokenSync x(true); // is cms thread | |
| 2308 if (waitForForegroundGC()) { | |
| 2309 // We yielded to a foreground GC, nothing more to be | |
| 2310 // done this round. | |
| 2311 assert(_foregroundGCShouldWait == false, "We set it to false in " | |
| 2312 "waitForForegroundGC()"); | |
| 2313 if (TraceCMSState) { | |
| 2314 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT | |
| 2315 " exiting collection CMS state %d", | |
| 2316 Thread::current(), _collectorState); | |
| 2317 } | |
| 2318 return; | |
| 2319 } else { | |
| 2320 // The background collector can run but check to see if the | |
| 2321 // foreground collector has done a collection while the | |
| 2322 // background collector was waiting to get the CGC_lock | |
| 2323 // above. If yes, break so that _foregroundGCShouldWait | |
| 2324 // is cleared before returning. | |
| 2325 if (_collectorState == Idling) { | |
| 2326 break; | |
| 2327 } | |
| 2328 } | |
| 2329 } | |
| 2330 | |
| 2331 assert(_foregroundGCShouldWait, "Foreground collector, if active, " | |
| 2332 "should be waiting"); | |
| 2333 | |
| 2334 switch (_collectorState) { | |
| 2335 case InitialMarking: | |
| 2336 { | |
| 2337 ReleaseForegroundGC x(this); | |
| 2338 stats().record_cms_begin(); | |
| 2339 VM_CMS_Initial_Mark initial_mark_op(this); | |
| 2340 VMThread::execute(&initial_mark_op); | |
| 2341 } | |
| 2342 // The collector state may be any legal state at this point | |
| 2343 // since the background collector may have yielded to the | |
| 2344 // foreground collector. | |
| 2345 break; | |
| 2346 case Marking: | |
| 2347 // initial marking in checkpointRootsInitialWork has been completed | |
| 2348 if (markFromRoots(true)) { // we were successful | |
| 2349 assert(_collectorState == Precleaning, "Collector state should " | |
| 2350 "have changed"); | |
| 2351 } else { | |
| 2352 assert(_foregroundGCIsActive, "Internal state inconsistency"); | |
| 2353 } | |
| 2354 break; | |
| 2355 case Precleaning: | |
| 2356 if (UseAdaptiveSizePolicy) { | |
| 2357 size_policy()->concurrent_precleaning_begin(); | |
| 2358 } | |
| 2359 // marking from roots in markFromRoots has been completed | |
| 2360 preclean(); | |
| 2361 if (UseAdaptiveSizePolicy) { | |
| 2362 size_policy()->concurrent_precleaning_end(); | |
| 2363 } | |
| 2364 assert(_collectorState == AbortablePreclean || | |
| 2365 _collectorState == FinalMarking, | |
| 2366 "Collector state should have changed"); | |
| 2367 break; | |
| 2368 case AbortablePreclean: | |
| 2369 if (UseAdaptiveSizePolicy) { | |
| 2370 size_policy()->concurrent_phases_resume(); | |
| 2371 } | |
| 2372 abortable_preclean(); | |
| 2373 if (UseAdaptiveSizePolicy) { | |
| 2374 size_policy()->concurrent_precleaning_end(); | |
| 2375 } | |
| 2376 assert(_collectorState == FinalMarking, "Collector state should " | |
| 2377 "have changed"); | |
| 2378 break; | |
| 2379 case FinalMarking: | |
| 2380 { | |
| 2381 ReleaseForegroundGC x(this); | |
| 2382 | |
| 2383 VM_CMS_Final_Remark final_remark_op(this); | |
| 2384 VMThread::execute(&final_remark_op); | |
| 935 | 2385 } |
| 0 | 2386 assert(_foregroundGCShouldWait, "block post-condition"); |
| 2387 break; | |
| 2388 case Sweeping: | |
| 2389 if (UseAdaptiveSizePolicy) { | |
| 2390 size_policy()->concurrent_sweeping_begin(); | |
| 2391 } | |
| 2392 // final marking in checkpointRootsFinal has been completed | |
| 2393 sweep(true); | |
| 2394 assert(_collectorState == Resizing, "Collector state change " | |
| 2395 "to Resizing must be done under the free_list_lock"); | |
| 2396 _full_gcs_since_conc_gc = 0; | |
| 2397 | |
| 2398 // Stop the timers for adaptive size policy for the concurrent phases | |
| 2399 if (UseAdaptiveSizePolicy) { | |
| 2400 size_policy()->concurrent_sweeping_end(); | |
| 2401 size_policy()->concurrent_phases_end(gch->gc_cause(), | |
| 2402 gch->prev_gen(_cmsGen)->capacity(), | |
| 2403 _cmsGen->free()); | |
| 2404 } | |
| 2405 | |
| 2406 case Resizing: { | |
| 2407 // Sweeping has been completed... | |
| 2408 // At this point the background collection has completed. | |
| 2409 // Don't move the call to compute_new_size() down | |
| 2410 // into code that might be executed if the background | |
| 2411 // collection was preempted. | |
| 2412 { | |
| 2413 ReleaseForegroundGC x(this); // unblock FG collection | |
| 2414 MutexLockerEx y(Heap_lock, Mutex::_no_safepoint_check_flag); | |
| 2415 CMSTokenSync z(true); // not strictly needed. | |
| 2416 if (_collectorState == Resizing) { | |
| 2417 compute_new_size(); | |
| 10405 | 2418 save_heap_summary(); |
| 0 | 2419 _collectorState = Resetting; |
| 2420 } else { | |
| 2421 assert(_collectorState == Idling, "The state should only change" | |
| 2422 " because the foreground collector has finished the collection"); | |
| 2423 } | |
| 2424 } | |
| 2425 break; | |
| 2426 } | |
| 2427 case Resetting: | |
| 2428 // CMS heap resizing has been completed | |
| 2429 reset(true); | |
| 2430 assert(_collectorState == Idling, "Collector state should " | |
| 2431 "have changed"); | |
|
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2432 |
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2433 MetaspaceGC::set_should_concurrent_collect(false); |
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2434 |
| 0 | 2435 stats().record_cms_end(); |
| 2436 // Don't move the concurrent_phases_end() and compute_new_size() | |
| 2437 // calls to here because a preempted background collection | |
| 2438 // has it's state set to "Resetting". | |
| 2439 break; | |
| 2440 case Idling: | |
| 2441 default: | |
| 2442 ShouldNotReachHere(); | |
| 2443 break; | |
| 2444 } | |
| 2445 if (TraceCMSState) { | |
| 2446 gclog_or_tty->print_cr(" Thread " INTPTR_FORMAT " done - next CMS state %d", | |
| 2447 Thread::current(), _collectorState); | |
| 2448 } | |
| 2449 assert(_foregroundGCShouldWait, "block post-condition"); | |
| 2450 } | |
| 2451 | |
| 2452 // Should this be in gc_epilogue? | |
| 2453 collector_policy()->counters()->update_counters(); | |
| 2454 | |
| 2455 { | |
| 2456 // Clear _foregroundGCShouldWait and, in the event that the | |
| 2457 // foreground collector is waiting, notify it, before | |
| 2458 // returning. | |
| 2459 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
| 2460 _foregroundGCShouldWait = false; | |
| 2461 if (_foregroundGCIsActive) { | |
| 2462 CGC_lock->notify(); | |
| 2463 } | |
| 2464 assert(!ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 2465 "Possible deadlock"); | |
| 2466 } | |
| 2467 if (TraceCMSState) { | |
| 2468 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT | |
| 2469 " exiting collection CMS state %d", | |
| 2470 Thread::current(), _collectorState); | |
| 2471 } | |
| 2472 if (PrintGC && Verbose) { | |
| 2473 _cmsGen->print_heap_change(prev_used); | |
| 2474 } | |
| 2475 } | |
| 2476 | |
| 10405 | 2477 void CMSCollector::register_foreground_gc_start(GCCause::Cause cause) { |
| 2478 if (!_cms_start_registered) { | |
| 2479 register_gc_start(cause); | |
| 2480 } | |
| 2481 } | |
| 2482 | |
| 2483 void CMSCollector::register_gc_start(GCCause::Cause cause) { | |
| 2484 _cms_start_registered = true; | |
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2485 _gc_timer_cm->register_gc_start(); |
| 10405 | 2486 _gc_tracer_cm->report_gc_start(cause, _gc_timer_cm->gc_start()); |
| 2487 } | |
| 2488 | |
| 2489 void CMSCollector::register_gc_end() { | |
| 2490 if (_cms_start_registered) { | |
| 2491 report_heap_summary(GCWhen::AfterGC); | |
| 2492 | |
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2493 _gc_timer_cm->register_gc_end(); |
| 10405 | 2494 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); |
| 2495 _cms_start_registered = false; | |
| 2496 } | |
| 2497 } | |
| 2498 | |
| 2499 void CMSCollector::save_heap_summary() { | |
| 2500 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 2501 _last_heap_summary = gch->create_heap_summary(); | |
| 2502 _last_metaspace_summary = gch->create_metaspace_summary(); | |
| 2503 } | |
| 2504 | |
| 2505 void CMSCollector::report_heap_summary(GCWhen::Type when) { | |
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2506 _gc_tracer_cm->report_gc_heap_summary(when, _last_heap_summary); |
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2507 _gc_tracer_cm->report_metaspace_summary(when, _last_metaspace_summary); |
| 10405 | 2508 } |
| 2509 | |
| 2510 void CMSCollector::collect_in_foreground(bool clear_all_soft_refs, GCCause::Cause cause) { | |
| 0 | 2511 assert(_foregroundGCIsActive && !_foregroundGCShouldWait, |
| 2512 "Foreground collector should be waiting, not executing"); | |
| 2513 assert(Thread::current()->is_VM_thread(), "A foreground collection" | |
| 2514 "may only be done by the VM Thread with the world stopped"); | |
| 2515 assert(ConcurrentMarkSweepThread::vm_thread_has_cms_token(), | |
| 2516 "VM thread should have CMS token"); | |
| 2517 | |
| 10405 | 2518 NOT_PRODUCT(GCTraceTime t("CMS:MS (foreground) ", PrintGCDetails && Verbose, |
| 2519 true, NULL);) | |
| 0 | 2520 if (UseAdaptiveSizePolicy) { |
| 2521 size_policy()->ms_collection_begin(); | |
| 2522 } | |
| 2523 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact); | |
| 2524 | |
| 2525 HandleMark hm; // Discard invalid handles created during verification | |
| 2526 | |
| 2527 if (VerifyBeforeGC && | |
| 2528 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
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2529 Universe::verify(); |
| 0 | 2530 } |
| 2531 | |
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2532 // Snapshot the soft reference policy to be used in this collection cycle. |
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2533 ref_processor()->setup_policy(clear_all_soft_refs); |
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2534 |
|
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|
2535 // Decide if class unloading should be done |
|
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|
2536 update_should_unload_classes(); |
|
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|
2537 |
| 0 | 2538 bool init_mark_was_synchronous = false; // until proven otherwise |
| 2539 while (_collectorState != Idling) { | |
| 2540 if (TraceCMSState) { | |
| 2541 gclog_or_tty->print_cr("Thread " INTPTR_FORMAT " in CMS state %d", | |
| 2542 Thread::current(), _collectorState); | |
| 2543 } | |
| 2544 switch (_collectorState) { | |
| 2545 case InitialMarking: | |
| 10405 | 2546 register_foreground_gc_start(cause); |
| 0 | 2547 init_mark_was_synchronous = true; // fact to be exploited in re-mark |
| 2548 checkpointRootsInitial(false); | |
| 2549 assert(_collectorState == Marking, "Collector state should have changed" | |
| 2550 " within checkpointRootsInitial()"); | |
| 2551 break; | |
| 2552 case Marking: | |
| 2553 // initial marking in checkpointRootsInitialWork has been completed | |
| 2554 if (VerifyDuringGC && | |
| 2555 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
|
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|
2556 Universe::verify("Verify before initial mark: "); |
| 0 | 2557 } |
| 2558 { | |
| 2559 bool res = markFromRoots(false); | |
| 2560 assert(res && _collectorState == FinalMarking, "Collector state should " | |
| 2561 "have changed"); | |
| 2562 break; | |
| 2563 } | |
| 2564 case FinalMarking: | |
| 2565 if (VerifyDuringGC && | |
| 2566 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
|
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|
2567 Universe::verify("Verify before re-mark: "); |
| 0 | 2568 } |
| 2569 checkpointRootsFinal(false, clear_all_soft_refs, | |
| 2570 init_mark_was_synchronous); | |
| 2571 assert(_collectorState == Sweeping, "Collector state should not " | |
| 2572 "have changed within checkpointRootsFinal()"); | |
| 2573 break; | |
| 2574 case Sweeping: | |
| 2575 // final marking in checkpointRootsFinal has been completed | |
| 2576 if (VerifyDuringGC && | |
| 2577 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
|
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|
2578 Universe::verify("Verify before sweep: "); |
| 0 | 2579 } |
| 2580 sweep(false); | |
| 2581 assert(_collectorState == Resizing, "Incorrect state"); | |
| 2582 break; | |
| 2583 case Resizing: { | |
| 2584 // Sweeping has been completed; the actual resize in this case | |
| 2585 // is done separately; nothing to be done in this state. | |
| 2586 _collectorState = Resetting; | |
| 2587 break; | |
| 2588 } | |
| 2589 case Resetting: | |
| 2590 // The heap has been resized. | |
| 2591 if (VerifyDuringGC && | |
| 2592 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
|
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|
2593 Universe::verify("Verify before reset: "); |
| 0 | 2594 } |
| 10405 | 2595 save_heap_summary(); |
| 0 | 2596 reset(false); |
| 2597 assert(_collectorState == Idling, "Collector state should " | |
| 2598 "have changed"); | |
| 2599 break; | |
| 2600 case Precleaning: | |
| 2601 case AbortablePreclean: | |
| 2602 // Elide the preclean phase | |
| 2603 _collectorState = FinalMarking; | |
| 2604 break; | |
| 2605 default: | |
| 2606 ShouldNotReachHere(); | |
| 2607 } | |
| 2608 if (TraceCMSState) { | |
| 2609 gclog_or_tty->print_cr(" Thread " INTPTR_FORMAT " done - next CMS state %d", | |
| 2610 Thread::current(), _collectorState); | |
| 2611 } | |
| 2612 } | |
| 2613 | |
| 2614 if (UseAdaptiveSizePolicy) { | |
| 2615 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 2616 size_policy()->ms_collection_end(gch->gc_cause()); | |
| 2617 } | |
| 2618 | |
| 2619 if (VerifyAfterGC && | |
| 2620 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
|
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|
2621 Universe::verify(); |
| 0 | 2622 } |
| 2623 if (TraceCMSState) { | |
| 2624 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT | |
| 2625 " exiting collection CMS state %d", | |
| 2626 Thread::current(), _collectorState); | |
| 2627 } | |
| 2628 } | |
| 2629 | |
| 2630 bool CMSCollector::waitForForegroundGC() { | |
| 2631 bool res = false; | |
| 2632 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 2633 "CMS thread should have CMS token"); | |
| 2634 // Block the foreground collector until the | |
| 2635 // background collectors decides whether to | |
| 2636 // yield. | |
| 2637 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
| 2638 _foregroundGCShouldWait = true; | |
| 2639 if (_foregroundGCIsActive) { | |
| 2640 // The background collector yields to the | |
| 2641 // foreground collector and returns a value | |
| 2642 // indicating that it has yielded. The foreground | |
| 2643 // collector can proceed. | |
| 2644 res = true; | |
| 2645 _foregroundGCShouldWait = false; | |
| 2646 ConcurrentMarkSweepThread::clear_CMS_flag( | |
| 2647 ConcurrentMarkSweepThread::CMS_cms_has_token); | |
| 2648 ConcurrentMarkSweepThread::set_CMS_flag( | |
| 2649 ConcurrentMarkSweepThread::CMS_cms_wants_token); | |
| 2650 // Get a possibly blocked foreground thread going | |
| 2651 CGC_lock->notify(); | |
| 2652 if (TraceCMSState) { | |
| 2653 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT " waiting at CMS state %d", | |
| 2654 Thread::current(), _collectorState); | |
| 2655 } | |
| 2656 while (_foregroundGCIsActive) { | |
| 2657 CGC_lock->wait(Mutex::_no_safepoint_check_flag); | |
| 2658 } | |
| 2659 ConcurrentMarkSweepThread::set_CMS_flag( | |
| 2660 ConcurrentMarkSweepThread::CMS_cms_has_token); | |
| 2661 ConcurrentMarkSweepThread::clear_CMS_flag( | |
| 2662 ConcurrentMarkSweepThread::CMS_cms_wants_token); | |
| 2663 } | |
| 2664 if (TraceCMSState) { | |
| 2665 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT " continuing at CMS state %d", | |
| 2666 Thread::current(), _collectorState); | |
| 2667 } | |
| 2668 return res; | |
| 2669 } | |
| 2670 | |
| 2671 // Because of the need to lock the free lists and other structures in | |
| 2672 // the collector, common to all the generations that the collector is | |
| 2673 // collecting, we need the gc_prologues of individual CMS generations | |
| 2674 // delegate to their collector. It may have been simpler had the | |
| 2675 // current infrastructure allowed one to call a prologue on a | |
| 2676 // collector. In the absence of that we have the generation's | |
| 2677 // prologue delegate to the collector, which delegates back | |
| 2678 // some "local" work to a worker method in the individual generations | |
| 2679 // that it's responsible for collecting, while itself doing any | |
| 2680 // work common to all generations it's responsible for. A similar | |
| 2681 // comment applies to the gc_epilogue()'s. | |
| 2682 // The role of the varaible _between_prologue_and_epilogue is to | |
| 2683 // enforce the invocation protocol. | |
| 2684 void CMSCollector::gc_prologue(bool full) { | |
|
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2685 // Call gc_prologue_work() for the CMSGen |
| 0 | 2686 // we are responsible for. |
| 2687 | |
| 2688 // The following locking discipline assumes that we are only called | |
| 2689 // when the world is stopped. | |
| 2690 assert(SafepointSynchronize::is_at_safepoint(), "world is stopped assumption"); | |
| 2691 | |
| 2692 // The CMSCollector prologue must call the gc_prologues for the | |
|
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|
2693 // "generations" that it's responsible |
| 0 | 2694 // for. |
| 2695 | |
| 2696 assert( Thread::current()->is_VM_thread() | |
| 2697 || ( CMSScavengeBeforeRemark | |
| 2698 && Thread::current()->is_ConcurrentGC_thread()), | |
| 2699 "Incorrect thread type for prologue execution"); | |
| 2700 | |
| 2701 if (_between_prologue_and_epilogue) { | |
| 2702 // We have already been invoked; this is a gc_prologue delegation | |
| 2703 // from yet another CMS generation that we are responsible for, just | |
| 2704 // ignore it since all relevant work has already been done. | |
| 2705 return; | |
| 2706 } | |
| 2707 | |
| 2708 // set a bit saying prologue has been called; cleared in epilogue | |
| 2709 _between_prologue_and_epilogue = true; | |
| 2710 // Claim locks for common data structures, then call gc_prologue_work() | |
|
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|
2711 // for each CMSGen. |
| 0 | 2712 |
| 2713 getFreelistLocks(); // gets free list locks on constituent spaces | |
| 2714 bitMapLock()->lock_without_safepoint_check(); | |
| 2715 | |
| 2716 // Should call gc_prologue_work() for all cms gens we are responsible for | |
|
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|
2717 bool duringMarking = _collectorState >= Marking |
| 0 | 2718 && _collectorState < Sweeping; |
|
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2719 |
|
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|
2720 // The young collections clear the modified oops state, which tells if |
|
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|
2721 // there are any modified oops in the class. The remark phase also needs |
|
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|
2722 // that information. Tell the young collection to save the union of all |
|
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|
2723 // modified klasses. |
|
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|
2724 if (duringMarking) { |
|
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|
2725 _ct->klass_rem_set()->set_accumulate_modified_oops(true); |
|
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|
2726 } |
|
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|
2727 |
|
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|
2728 bool registerClosure = duringMarking; |
|
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|
2729 |
|
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|
2730 ModUnionClosure* muc = CollectedHeap::use_parallel_gc_threads() ? |
|
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|
2731 &_modUnionClosurePar |
| 0 | 2732 : &_modUnionClosure; |
| 2733 _cmsGen->gc_prologue_work(full, registerClosure, muc); | |
| 2734 | |
| 2735 if (!full) { | |
| 2736 stats().record_gc0_begin(); | |
| 2737 } | |
| 2738 } | |
| 2739 | |
| 2740 void ConcurrentMarkSweepGeneration::gc_prologue(bool full) { | |
|
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|
2741 |
|
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|
2742 _capacity_at_prologue = capacity(); |
|
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diff
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|
2743 _used_at_prologue = used(); |
|
8617e38bb4cb
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diff
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|
2744 |
| 0 | 2745 // Delegate to CMScollector which knows how to coordinate between |
| 2746 // this and any other CMS generations that it is responsible for | |
| 2747 // collecting. | |
| 2748 collector()->gc_prologue(full); | |
| 2749 } | |
| 2750 | |
| 2751 // This is a "private" interface for use by this generation's CMSCollector. | |
| 2752 // Not to be called directly by any other entity (for instance, | |
| 2753 // GenCollectedHeap, which calls the "public" gc_prologue method above). | |
| 2754 void ConcurrentMarkSweepGeneration::gc_prologue_work(bool full, | |
| 2755 bool registerClosure, ModUnionClosure* modUnionClosure) { | |
| 2756 assert(!incremental_collection_failed(), "Shouldn't be set yet"); | |
| 2757 assert(cmsSpace()->preconsumptionDirtyCardClosure() == NULL, | |
| 2758 "Should be NULL"); | |
| 2759 if (registerClosure) { | |
| 2760 cmsSpace()->setPreconsumptionDirtyCardClosure(modUnionClosure); | |
| 2761 } | |
| 2762 cmsSpace()->gc_prologue(); | |
| 2763 // Clear stat counters | |
| 2764 NOT_PRODUCT( | |
| 2765 assert(_numObjectsPromoted == 0, "check"); | |
| 2766 assert(_numWordsPromoted == 0, "check"); | |
| 2767 if (Verbose && PrintGC) { | |
| 2768 gclog_or_tty->print("Allocated "SIZE_FORMAT" objects, " | |
| 2769 SIZE_FORMAT" bytes concurrently", | |
| 2770 _numObjectsAllocated, _numWordsAllocated*sizeof(HeapWord)); | |
| 2771 } | |
| 2772 _numObjectsAllocated = 0; | |
| 2773 _numWordsAllocated = 0; | |
| 2774 ) | |
| 2775 } | |
| 2776 | |
| 2777 void CMSCollector::gc_epilogue(bool full) { | |
| 2778 // The following locking discipline assumes that we are only called | |
| 2779 // when the world is stopped. | |
| 2780 assert(SafepointSynchronize::is_at_safepoint(), | |
| 2781 "world is stopped assumption"); | |
| 2782 | |
| 2783 // Currently the CMS epilogue (see CompactibleFreeListSpace) merely checks | |
| 2784 // if linear allocation blocks need to be appropriately marked to allow the | |
| 2785 // the blocks to be parsable. We also check here whether we need to nudge the | |
| 2786 // CMS collector thread to start a new cycle (if it's not already active). | |
| 2787 assert( Thread::current()->is_VM_thread() | |
| 2788 || ( CMSScavengeBeforeRemark | |
| 2789 && Thread::current()->is_ConcurrentGC_thread()), | |
| 2790 "Incorrect thread type for epilogue execution"); | |
| 2791 | |
| 2792 if (!_between_prologue_and_epilogue) { | |
| 2793 // We have already been invoked; this is a gc_epilogue delegation | |
| 2794 // from yet another CMS generation that we are responsible for, just | |
| 2795 // ignore it since all relevant work has already been done. | |
| 2796 return; | |
| 2797 } | |
| 2798 assert(haveFreelistLocks(), "must have freelist locks"); | |
| 2799 assert_lock_strong(bitMapLock()); | |
| 2800 | |
|
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|
2801 _ct->klass_rem_set()->set_accumulate_modified_oops(false); |
|
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|
2802 |
| 0 | 2803 _cmsGen->gc_epilogue_work(full); |
| 2804 | |
| 2805 if (_collectorState == AbortablePreclean || _collectorState == Precleaning) { | |
| 2806 // in case sampling was not already enabled, enable it | |
| 2807 _start_sampling = true; | |
| 2808 } | |
| 2809 // reset _eden_chunk_array so sampling starts afresh | |
| 2810 _eden_chunk_index = 0; | |
| 2811 | |
| 2812 size_t cms_used = _cmsGen->cmsSpace()->used(); | |
| 2813 | |
| 2814 // update performance counters - this uses a special version of | |
| 2815 // update_counters() that allows the utilization to be passed as a | |
| 2816 // parameter, avoiding multiple calls to used(). | |
| 2817 // | |
| 2818 _cmsGen->update_counters(cms_used); | |
| 2819 | |
| 2820 if (CMSIncrementalMode) { | |
| 2821 icms_update_allocation_limits(); | |
| 2822 } | |
| 2823 | |
| 2824 bitMapLock()->unlock(); | |
| 2825 releaseFreelistLocks(); | |
| 2826 | |
|
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|
2827 if (!CleanChunkPoolAsync) { |
|
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|
2828 Chunk::clean_chunk_pool(); |
|
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|
2829 } |
|
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|
2830 |
|
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10243
diff
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|
2831 set_did_compact(false); |
| 0 | 2832 _between_prologue_and_epilogue = false; // ready for next cycle |
| 2833 } | |
| 2834 | |
| 2835 void ConcurrentMarkSweepGeneration::gc_epilogue(bool full) { | |
| 2836 collector()->gc_epilogue(full); | |
| 2837 | |
| 2838 // Also reset promotion tracking in par gc thread states. | |
|
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|
2839 if (CollectedHeap::use_parallel_gc_threads()) { |
| 0 | 2840 for (uint i = 0; i < ParallelGCThreads; i++) { |
|
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|
2841 _par_gc_thread_states[i]->promo.stopTrackingPromotions(i); |
| 0 | 2842 } |
| 2843 } | |
| 2844 } | |
| 2845 | |
| 2846 void ConcurrentMarkSweepGeneration::gc_epilogue_work(bool full) { | |
| 2847 assert(!incremental_collection_failed(), "Should have been cleared"); | |
| 2848 cmsSpace()->setPreconsumptionDirtyCardClosure(NULL); | |
| 2849 cmsSpace()->gc_epilogue(); | |
| 2850 // Print stat counters | |
| 2851 NOT_PRODUCT( | |
| 2852 assert(_numObjectsAllocated == 0, "check"); | |
| 2853 assert(_numWordsAllocated == 0, "check"); | |
| 2854 if (Verbose && PrintGC) { | |
| 2855 gclog_or_tty->print("Promoted "SIZE_FORMAT" objects, " | |
| 2856 SIZE_FORMAT" bytes", | |
| 2857 _numObjectsPromoted, _numWordsPromoted*sizeof(HeapWord)); | |
| 2858 } | |
| 2859 _numObjectsPromoted = 0; | |
| 2860 _numWordsPromoted = 0; | |
| 2861 ) | |
| 2862 | |
| 2863 if (PrintGC && Verbose) { | |
| 2864 // Call down the chain in contiguous_available needs the freelistLock | |
| 2865 // so print this out before releasing the freeListLock. | |
| 2866 gclog_or_tty->print(" Contiguous available "SIZE_FORMAT" bytes ", | |
| 2867 contiguous_available()); | |
| 2868 } | |
| 2869 } | |
| 2870 | |
| 2871 #ifndef PRODUCT | |
| 2872 bool CMSCollector::have_cms_token() { | |
| 2873 Thread* thr = Thread::current(); | |
| 2874 if (thr->is_VM_thread()) { | |
| 2875 return ConcurrentMarkSweepThread::vm_thread_has_cms_token(); | |
| 2876 } else if (thr->is_ConcurrentGC_thread()) { | |
| 2877 return ConcurrentMarkSweepThread::cms_thread_has_cms_token(); | |
| 2878 } else if (thr->is_GC_task_thread()) { | |
| 2879 return ConcurrentMarkSweepThread::vm_thread_has_cms_token() && | |
| 2880 ParGCRareEvent_lock->owned_by_self(); | |
| 2881 } | |
| 2882 return false; | |
| 2883 } | |
| 2884 #endif | |
| 2885 | |
| 2886 // Check reachability of the given heap address in CMS generation, | |
| 2887 // treating all other generations as roots. | |
| 2888 bool CMSCollector::is_cms_reachable(HeapWord* addr) { | |
| 2889 // We could "guarantee" below, rather than assert, but i'll | |
| 2890 // leave these as "asserts" so that an adventurous debugger | |
| 2891 // could try this in the product build provided some subset of | |
| 2892 // the conditions were met, provided they were intersted in the | |
| 2893 // results and knew that the computation below wouldn't interfere | |
| 2894 // with other concurrent computations mutating the structures | |
| 2895 // being read or written. | |
| 2896 assert(SafepointSynchronize::is_at_safepoint(), | |
| 2897 "Else mutations in object graph will make answer suspect"); | |
| 2898 assert(have_cms_token(), "Should hold cms token"); | |
| 2899 assert(haveFreelistLocks(), "must hold free list locks"); | |
| 2900 assert_lock_strong(bitMapLock()); | |
| 2901 | |
| 2902 // Clear the marking bit map array before starting, but, just | |
| 2903 // for kicks, first report if the given address is already marked | |
| 2904 gclog_or_tty->print_cr("Start: Address 0x%x is%s marked", addr, | |
| 2905 _markBitMap.isMarked(addr) ? "" : " not"); | |
| 2906 | |
| 2907 if (verify_after_remark()) { | |
| 2908 MutexLockerEx x(verification_mark_bm()->lock(), Mutex::_no_safepoint_check_flag); | |
| 2909 bool result = verification_mark_bm()->isMarked(addr); | |
| 2910 gclog_or_tty->print_cr("TransitiveMark: Address 0x%x %s marked", addr, | |
| 2911 result ? "IS" : "is NOT"); | |
| 2912 return result; | |
| 2913 } else { | |
| 2914 gclog_or_tty->print_cr("Could not compute result"); | |
| 2915 return false; | |
| 2916 } | |
| 2917 } | |
| 2918 | |
|
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|
2919 |
|
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|
2920 void |
|
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|
2921 CMSCollector::print_on_error(outputStream* st) { |
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2922 CMSCollector* collector = ConcurrentMarkSweepGeneration::_collector; |
|
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2923 if (collector != NULL) { |
|
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2924 CMSBitMap* bitmap = &collector->_markBitMap; |
|
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2925 st->print_cr("Marking Bits: (CMSBitMap*) " PTR_FORMAT, bitmap); |
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2926 bitmap->print_on_error(st, " Bits: "); |
|
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|
2927 |
|
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|
2928 st->cr(); |
|
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|
2929 |
|
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|
2930 CMSBitMap* mut_bitmap = &collector->_modUnionTable; |
|
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2931 st->print_cr("Mod Union Table: (CMSBitMap*) " PTR_FORMAT, mut_bitmap); |
|
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2932 mut_bitmap->print_on_error(st, " Bits: "); |
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2933 } |
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2934 } |
|
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|
2935 |
| 0 | 2936 //////////////////////////////////////////////////////// |
| 2937 // CMS Verification Support | |
| 2938 //////////////////////////////////////////////////////// | |
| 2939 // Following the remark phase, the following invariant | |
| 2940 // should hold -- each object in the CMS heap which is | |
| 2941 // marked in markBitMap() should be marked in the verification_mark_bm(). | |
| 2942 | |
| 2943 class VerifyMarkedClosure: public BitMapClosure { | |
| 2944 CMSBitMap* _marks; | |
| 2945 bool _failed; | |
| 2946 | |
| 2947 public: | |
| 2948 VerifyMarkedClosure(CMSBitMap* bm): _marks(bm), _failed(false) {} | |
| 2949 | |
|
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2950 bool do_bit(size_t offset) { |
| 0 | 2951 HeapWord* addr = _marks->offsetToHeapWord(offset); |
| 2952 if (!_marks->isMarked(addr)) { | |
|
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2953 oop(addr)->print_on(gclog_or_tty); |
| 0 | 2954 gclog_or_tty->print_cr(" ("INTPTR_FORMAT" should have been marked)", addr); |
| 2955 _failed = true; | |
| 2956 } | |
|
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2957 return true; |
| 0 | 2958 } |
| 2959 | |
| 2960 bool failed() { return _failed; } | |
| 2961 }; | |
| 2962 | |
|
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2963 bool CMSCollector::verify_after_remark(bool silent) { |
|
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2964 if (!silent) gclog_or_tty->print(" [Verifying CMS Marking... "); |
| 0 | 2965 MutexLockerEx ml(verification_mark_bm()->lock(), Mutex::_no_safepoint_check_flag); |
| 2966 static bool init = false; | |
| 2967 | |
| 2968 assert(SafepointSynchronize::is_at_safepoint(), | |
| 2969 "Else mutations in object graph will make answer suspect"); | |
| 2970 assert(have_cms_token(), | |
| 2971 "Else there may be mutual interference in use of " | |
| 2972 " verification data structures"); | |
| 2973 assert(_collectorState > Marking && _collectorState <= Sweeping, | |
| 2974 "Else marking info checked here may be obsolete"); | |
| 2975 assert(haveFreelistLocks(), "must hold free list locks"); | |
| 2976 assert_lock_strong(bitMapLock()); | |
| 2977 | |
| 2978 | |
| 2979 // Allocate marking bit map if not already allocated | |
| 2980 if (!init) { // first time | |
| 2981 if (!verification_mark_bm()->allocate(_span)) { | |
| 2982 return false; | |
| 2983 } | |
| 2984 init = true; | |
| 2985 } | |
| 2986 | |
| 2987 assert(verification_mark_stack()->isEmpty(), "Should be empty"); | |
| 2988 | |
| 2989 // Turn off refs discovery -- so we will be tracing through refs. | |
| 2990 // This is as intended, because by this time | |
| 2991 // GC must already have cleared any refs that need to be cleared, | |
| 2992 // and traced those that need to be marked; moreover, | |
| 2993 // the marking done here is not going to intefere in any | |
| 2994 // way with the marking information used by GC. | |
| 2995 NoRefDiscovery no_discovery(ref_processor()); | |
| 2996 | |
| 2997 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact;) | |
| 2998 | |
| 2999 // Clear any marks from a previous round | |
| 3000 verification_mark_bm()->clear_all(); | |
| 3001 assert(verification_mark_stack()->isEmpty(), "markStack should be empty"); | |
|
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3002 verify_work_stacks_empty(); |
| 0 | 3003 |
| 3004 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 3005 gch->ensure_parsability(false); // fill TLABs, but no need to retire them | |
| 3006 // Update the saved marks which may affect the root scans. | |
| 3007 gch->save_marks(); | |
| 3008 | |
| 3009 if (CMSRemarkVerifyVariant == 1) { | |
| 3010 // In this first variant of verification, we complete | |
| 3011 // all marking, then check if the new marks-verctor is | |
| 3012 // a subset of the CMS marks-vector. | |
| 3013 verify_after_remark_work_1(); | |
| 3014 } else if (CMSRemarkVerifyVariant == 2) { | |
| 3015 // In this second variant of verification, we flag an error | |
| 3016 // (i.e. an object reachable in the new marks-vector not reachable | |
| 3017 // in the CMS marks-vector) immediately, also indicating the | |
| 3018 // identify of an object (A) that references the unmarked object (B) -- | |
| 3019 // presumably, a mutation to A failed to be picked up by preclean/remark? | |
| 3020 verify_after_remark_work_2(); | |
| 3021 } else { | |
| 3022 warning("Unrecognized value %d for CMSRemarkVerifyVariant", | |
| 3023 CMSRemarkVerifyVariant); | |
| 3024 } | |
|
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3025 if (!silent) gclog_or_tty->print(" done] "); |
| 0 | 3026 return true; |
| 3027 } | |
| 3028 | |
| 3029 void CMSCollector::verify_after_remark_work_1() { | |
| 3030 ResourceMark rm; | |
| 3031 HandleMark hm; | |
| 3032 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 3033 | |
|
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3034 // Get a clear set of claim bits for the strong roots processing to work with. |
|
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3035 ClassLoaderDataGraph::clear_claimed_marks(); |
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3036 |
| 0 | 3037 // Mark from roots one level into CMS |
|
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3038 MarkRefsIntoClosure notOlder(_span, verification_mark_bm()); |
| 0 | 3039 gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel. |
| 3040 | |
| 3041 gch->gen_process_strong_roots(_cmsGen->level(), | |
| 3042 true, // younger gens are roots | |
|
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|
3043 true, // activate StrongRootsScope |
|
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3044 false, // not scavenging |
| 0 | 3045 SharedHeap::ScanningOption(roots_scanning_options()), |
|
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|
3046 ¬Older, |
|
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3047 true, // walk code active on stacks |
|
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3048 NULL, |
|
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|
3049 NULL); // SSS: Provide correct closure |
| 0 | 3050 |
| 3051 // Now mark from the roots | |
| 3052 MarkFromRootsClosure markFromRootsClosure(this, _span, | |
|
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|
3053 verification_mark_bm(), verification_mark_stack(), |
| 0 | 3054 false /* don't yield */, true /* verifying */); |
| 3055 assert(_restart_addr == NULL, "Expected pre-condition"); | |
| 3056 verification_mark_bm()->iterate(&markFromRootsClosure); | |
| 3057 while (_restart_addr != NULL) { | |
| 3058 // Deal with stack overflow: by restarting at the indicated | |
| 3059 // address. | |
| 3060 HeapWord* ra = _restart_addr; | |
| 3061 markFromRootsClosure.reset(ra); | |
| 3062 _restart_addr = NULL; | |
| 3063 verification_mark_bm()->iterate(&markFromRootsClosure, ra, _span.end()); | |
| 3064 } | |
| 3065 assert(verification_mark_stack()->isEmpty(), "Should have been drained"); | |
| 3066 verify_work_stacks_empty(); | |
| 3067 | |
| 3068 // Marking completed -- now verify that each bit marked in | |
| 3069 // verification_mark_bm() is also marked in markBitMap(); flag all | |
| 3070 // errors by printing corresponding objects. | |
| 3071 VerifyMarkedClosure vcl(markBitMap()); | |
| 3072 verification_mark_bm()->iterate(&vcl); | |
| 3073 if (vcl.failed()) { | |
| 3074 gclog_or_tty->print("Verification failed"); | |
|
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|
3075 Universe::heap()->print_on(gclog_or_tty); |
|
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|
3076 fatal("CMS: failed marking verification after remark"); |
| 0 | 3077 } |
| 3078 } | |
| 3079 | |
|
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3080 class VerifyKlassOopsKlassClosure : public KlassClosure { |
|
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3081 class VerifyKlassOopsClosure : public OopClosure { |
|
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|
3082 CMSBitMap* _bitmap; |
|
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3083 public: |
|
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|
3084 VerifyKlassOopsClosure(CMSBitMap* bitmap) : _bitmap(bitmap) { } |
|
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|
3085 void do_oop(oop* p) { guarantee(*p == NULL || _bitmap->isMarked((HeapWord*) *p), "Should be marked"); } |
|
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|
3086 void do_oop(narrowOop* p) { ShouldNotReachHere(); } |
|
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|
3087 } _oop_closure; |
|
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3088 public: |
|
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|
3089 VerifyKlassOopsKlassClosure(CMSBitMap* bitmap) : _oop_closure(bitmap) {} |
|
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|
3090 void do_klass(Klass* k) { |
|
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|
3091 k->oops_do(&_oop_closure); |
|
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|
3092 } |
|
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|
3093 }; |
|
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|
3094 |
| 0 | 3095 void CMSCollector::verify_after_remark_work_2() { |
| 3096 ResourceMark rm; | |
| 3097 HandleMark hm; | |
| 3098 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 3099 | |
|
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|
3100 // Get a clear set of claim bits for the strong roots processing to work with. |
|
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|
3101 ClassLoaderDataGraph::clear_claimed_marks(); |
|
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|
3102 |
| 0 | 3103 // Mark from roots one level into CMS |
| 3104 MarkRefsIntoVerifyClosure notOlder(_span, verification_mark_bm(), | |
|
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|
3105 markBitMap()); |
|
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|
3106 CMKlassClosure klass_closure(¬Older); |
|
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|
3107 |
| 0 | 3108 gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel. |
| 3109 gch->gen_process_strong_roots(_cmsGen->level(), | |
| 3110 true, // younger gens are roots | |
|
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|
3111 true, // activate StrongRootsScope |
|
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|
3112 false, // not scavenging |
| 0 | 3113 SharedHeap::ScanningOption(roots_scanning_options()), |
|
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|
3114 ¬Older, |
|
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|
3115 true, // walk code active on stacks |
|
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|
3116 NULL, |
|
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|
3117 &klass_closure); |
| 0 | 3118 |
| 3119 // Now mark from the roots | |
| 3120 MarkFromRootsVerifyClosure markFromRootsClosure(this, _span, | |
| 3121 verification_mark_bm(), markBitMap(), verification_mark_stack()); | |
| 3122 assert(_restart_addr == NULL, "Expected pre-condition"); | |
| 3123 verification_mark_bm()->iterate(&markFromRootsClosure); | |
| 3124 while (_restart_addr != NULL) { | |
| 3125 // Deal with stack overflow: by restarting at the indicated | |
| 3126 // address. | |
| 3127 HeapWord* ra = _restart_addr; | |
| 3128 markFromRootsClosure.reset(ra); | |
| 3129 _restart_addr = NULL; | |
| 3130 verification_mark_bm()->iterate(&markFromRootsClosure, ra, _span.end()); | |
| 3131 } | |
| 3132 assert(verification_mark_stack()->isEmpty(), "Should have been drained"); | |
| 3133 verify_work_stacks_empty(); | |
|
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|
3134 |
|
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|
3135 VerifyKlassOopsKlassClosure verify_klass_oops(verification_mark_bm()); |
|
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|
3136 ClassLoaderDataGraph::classes_do(&verify_klass_oops); |
| 0 | 3137 |
| 3138 // Marking completed -- now verify that each bit marked in | |
| 3139 // verification_mark_bm() is also marked in markBitMap(); flag all | |
| 3140 // errors by printing corresponding objects. | |
| 3141 VerifyMarkedClosure vcl(markBitMap()); | |
| 3142 verification_mark_bm()->iterate(&vcl); | |
| 3143 assert(!vcl.failed(), "Else verification above should not have succeeded"); | |
| 3144 } | |
| 3145 | |
| 3146 void ConcurrentMarkSweepGeneration::save_marks() { | |
| 3147 // delegate to CMS space | |
| 3148 cmsSpace()->save_marks(); | |
| 3149 for (uint i = 0; i < ParallelGCThreads; i++) { | |
| 3150 _par_gc_thread_states[i]->promo.startTrackingPromotions(); | |
| 3151 } | |
| 3152 } | |
| 3153 | |
| 3154 bool ConcurrentMarkSweepGeneration::no_allocs_since_save_marks() { | |
| 3155 return cmsSpace()->no_allocs_since_save_marks(); | |
| 3156 } | |
| 3157 | |
| 3158 #define CMS_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \ | |
| 3159 \ | |
| 3160 void ConcurrentMarkSweepGeneration:: \ | |
| 3161 oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) { \ | |
| 3162 cl->set_generation(this); \ | |
| 3163 cmsSpace()->oop_since_save_marks_iterate##nv_suffix(cl); \ | |
| 3164 cl->reset_generation(); \ | |
| 3165 save_marks(); \ | |
| 3166 } | |
| 3167 | |
| 3168 ALL_SINCE_SAVE_MARKS_CLOSURES(CMS_SINCE_SAVE_MARKS_DEFN) | |
| 3169 | |
| 3170 void | |
| 3171 ConcurrentMarkSweepGeneration::younger_refs_iterate(OopsInGenClosure* cl) { | |
| 3172 cl->set_generation(this); | |
| 3173 younger_refs_in_space_iterate(_cmsSpace, cl); | |
| 3174 cl->reset_generation(); | |
| 3175 } | |
| 3176 | |
| 3177 void | |
|
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3178 ConcurrentMarkSweepGeneration::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) { |
| 0 | 3179 if (freelistLock()->owned_by_self()) { |
| 3180 Generation::oop_iterate(mr, cl); | |
| 3181 } else { | |
| 3182 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 3183 Generation::oop_iterate(mr, cl); | |
| 3184 } | |
| 3185 } | |
| 3186 | |
| 3187 void | |
|
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3188 ConcurrentMarkSweepGeneration::oop_iterate(ExtendedOopClosure* cl) { |
| 0 | 3189 if (freelistLock()->owned_by_self()) { |
| 3190 Generation::oop_iterate(cl); | |
| 3191 } else { | |
| 3192 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 3193 Generation::oop_iterate(cl); | |
| 3194 } | |
| 3195 } | |
| 3196 | |
| 3197 void | |
| 3198 ConcurrentMarkSweepGeneration::object_iterate(ObjectClosure* cl) { | |
| 3199 if (freelistLock()->owned_by_self()) { | |
| 3200 Generation::object_iterate(cl); | |
| 3201 } else { | |
| 3202 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 3203 Generation::object_iterate(cl); | |
| 3204 } | |
| 3205 } | |
| 3206 | |
| 3207 void | |
|
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3208 ConcurrentMarkSweepGeneration::safe_object_iterate(ObjectClosure* cl) { |
|
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3209 if (freelistLock()->owned_by_self()) { |
|
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3210 Generation::safe_object_iterate(cl); |
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3211 } else { |
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|
3212 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); |
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3213 Generation::safe_object_iterate(cl); |
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3214 } |
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|
3215 } |
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3216 |
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|
3217 void |
| 0 | 3218 ConcurrentMarkSweepGeneration::post_compact() { |
| 3219 } | |
| 3220 | |
| 3221 void | |
| 3222 ConcurrentMarkSweepGeneration::prepare_for_verify() { | |
| 3223 // Fix the linear allocation blocks to look like free blocks. | |
| 3224 | |
| 3225 // Locks are normally acquired/released in gc_prologue/gc_epilogue, but those | |
| 3226 // are not called when the heap is verified during universe initialization and | |
| 3227 // at vm shutdown. | |
| 3228 if (freelistLock()->owned_by_self()) { | |
| 3229 cmsSpace()->prepare_for_verify(); | |
| 3230 } else { | |
| 3231 MutexLockerEx fll(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 3232 cmsSpace()->prepare_for_verify(); | |
| 3233 } | |
| 3234 } | |
| 3235 | |
| 3236 void | |
| 6008 | 3237 ConcurrentMarkSweepGeneration::verify() { |
| 0 | 3238 // Locks are normally acquired/released in gc_prologue/gc_epilogue, but those |
| 3239 // are not called when the heap is verified during universe initialization and | |
| 3240 // at vm shutdown. | |
| 3241 if (freelistLock()->owned_by_self()) { | |
| 6008 | 3242 cmsSpace()->verify(); |
| 0 | 3243 } else { |
| 3244 MutexLockerEx fll(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 6008 | 3245 cmsSpace()->verify(); |
| 3246 } | |
| 3247 } | |
| 3248 | |
| 3249 void CMSCollector::verify() { | |
| 3250 _cmsGen->verify(); | |
| 0 | 3251 } |
| 3252 | |
| 3253 #ifndef PRODUCT | |
| 3254 bool CMSCollector::overflow_list_is_empty() const { | |
| 3255 assert(_num_par_pushes >= 0, "Inconsistency"); | |
| 3256 if (_overflow_list == NULL) { | |
| 3257 assert(_num_par_pushes == 0, "Inconsistency"); | |
| 3258 } | |
| 3259 return _overflow_list == NULL; | |
| 3260 } | |
| 3261 | |
| 3262 // The methods verify_work_stacks_empty() and verify_overflow_empty() | |
| 3263 // merely consolidate assertion checks that appear to occur together frequently. | |
| 3264 void CMSCollector::verify_work_stacks_empty() const { | |
| 3265 assert(_markStack.isEmpty(), "Marking stack should be empty"); | |
| 3266 assert(overflow_list_is_empty(), "Overflow list should be empty"); | |
| 3267 } | |
| 3268 | |
| 3269 void CMSCollector::verify_overflow_empty() const { | |
| 3270 assert(overflow_list_is_empty(), "Overflow list should be empty"); | |
| 3271 assert(no_preserved_marks(), "No preserved marks"); | |
| 3272 } | |
| 3273 #endif // PRODUCT | |
| 3274 | |
|
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3275 // Decide if we want to enable class unloading as part of the |
|
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3276 // ensuing concurrent GC cycle. We will collect and |
|
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3277 // unload classes if it's the case that: |
|
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|
3278 // (1) an explicit gc request has been made and the flag |
|
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|
3279 // ExplicitGCInvokesConcurrentAndUnloadsClasses is set, OR |
|
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|
3280 // (2) (a) class unloading is enabled at the command line, and |
|
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3281 // (b) old gen is getting really full |
|
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3282 // NOTE: Provided there is no change in the state of the heap between |
|
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|
3283 // calls to this method, it should have idempotent results. Moreover, |
|
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|
3284 // its results should be monotonically increasing (i.e. going from 0 to 1, |
|
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|
3285 // but not 1 to 0) between successive calls between which the heap was |
|
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|
3286 // not collected. For the implementation below, it must thus rely on |
|
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|
3287 // the property that concurrent_cycles_since_last_unload() |
|
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3288 // will not decrease unless a collection cycle happened and that |
|
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3289 // _cmsGen->is_too_full() are |
|
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|
3290 // themselves also monotonic in that sense. See check_monotonicity() |
|
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|
3291 // below. |
|
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|
3292 void CMSCollector::update_should_unload_classes() { |
|
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3293 _should_unload_classes = false; |
|
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|
3294 // Condition 1 above |
|
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|
3295 if (_full_gc_requested && ExplicitGCInvokesConcurrentAndUnloadsClasses) { |
|
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|
3296 _should_unload_classes = true; |
|
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|
3297 } else if (CMSClassUnloadingEnabled) { // Condition 2.a above |
|
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|
3298 // Disjuncts 2.b.(i,ii,iii) above |
|
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|
3299 _should_unload_classes = (concurrent_cycles_since_last_unload() >= |
|
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|
3300 CMSClassUnloadingMaxInterval) |
|
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|
3301 || _cmsGen->is_too_full(); |
|
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|
3302 } |
|
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|
3303 } |
|
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|
3304 |
|
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|
3305 bool ConcurrentMarkSweepGeneration::is_too_full() const { |
|
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|
3306 bool res = should_concurrent_collect(); |
|
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|
3307 res = res && (occupancy() > (double)CMSIsTooFullPercentage/100.0); |
|
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|
3308 return res; |
|
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|
3309 } |
|
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|
3310 |
| 0 | 3311 void CMSCollector::setup_cms_unloading_and_verification_state() { |
|
3293
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|
3312 const bool should_verify = VerifyBeforeGC || VerifyAfterGC || VerifyDuringGC |
| 0 | 3313 || VerifyBeforeExit; |
|
3293
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|
3314 const int rso = SharedHeap::SO_Strings | SharedHeap::SO_CodeCache; |
| 0 | 3315 |
|
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3316 // We set the proper root for this CMS cycle here. |
|
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3317 if (should_unload_classes()) { // Should unload classes this cycle |
|
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|
3318 remove_root_scanning_option(SharedHeap::SO_AllClasses); |
|
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|
3319 add_root_scanning_option(SharedHeap::SO_SystemClasses); |
| 0 | 3320 remove_root_scanning_option(rso); // Shrink the root set appropriately |
| 3321 set_verifying(should_verify); // Set verification state for this cycle | |
| 3322 return; // Nothing else needs to be done at this time | |
| 3323 } | |
| 3324 | |
| 3325 // Not unloading classes this cycle | |
|
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|
3326 assert(!should_unload_classes(), "Inconsitency!"); |
|
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|
3327 remove_root_scanning_option(SharedHeap::SO_SystemClasses); |
|
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3328 add_root_scanning_option(SharedHeap::SO_AllClasses); |
|
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|
3329 |
|
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|
3330 if ((!verifying() || unloaded_classes_last_cycle()) && should_verify) { |
| 0 | 3331 // Include symbols, strings and code cache elements to prevent their resurrection. |
| 3332 add_root_scanning_option(rso); | |
| 3333 set_verifying(true); | |
| 3334 } else if (verifying() && !should_verify) { | |
| 3335 // We were verifying, but some verification flags got disabled. | |
| 3336 set_verifying(false); | |
| 3337 // Exclude symbols, strings and code cache elements from root scanning to | |
| 3338 // reduce IM and RM pauses. | |
| 3339 remove_root_scanning_option(rso); | |
| 3340 } | |
| 3341 } | |
| 3342 | |
| 3343 | |
| 3344 #ifndef PRODUCT | |
| 3345 HeapWord* CMSCollector::block_start(const void* p) const { | |
| 3346 const HeapWord* addr = (HeapWord*)p; | |
| 3347 if (_span.contains(p)) { | |
| 3348 if (_cmsGen->cmsSpace()->is_in_reserved(addr)) { | |
| 3349 return _cmsGen->cmsSpace()->block_start(p); | |
| 3350 } | |
| 3351 } | |
| 3352 return NULL; | |
| 3353 } | |
| 3354 #endif | |
| 3355 | |
| 3356 HeapWord* | |
| 3357 ConcurrentMarkSweepGeneration::expand_and_allocate(size_t word_size, | |
| 3358 bool tlab, | |
| 3359 bool parallel) { | |
|
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|
3360 CMSSynchronousYieldRequest yr; |
| 0 | 3361 assert(!tlab, "Can't deal with TLAB allocation"); |
| 3362 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 3363 expand(word_size*HeapWordSize, MinHeapDeltaBytes, | |
| 3364 CMSExpansionCause::_satisfy_allocation); | |
| 3365 if (GCExpandToAllocateDelayMillis > 0) { | |
| 3366 os::sleep(Thread::current(), GCExpandToAllocateDelayMillis, false); | |
| 3367 } | |
|
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|
3368 return have_lock_and_allocate(word_size, tlab); |
| 0 | 3369 } |
| 3370 | |
| 3371 // YSR: All of this generation expansion/shrinking stuff is an exact copy of | |
| 3372 // OneContigSpaceCardGeneration, which makes me wonder if we should move this | |
| 3373 // to CardGeneration and share it... | |
|
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|
3374 bool ConcurrentMarkSweepGeneration::expand(size_t bytes, size_t expand_bytes) { |
|
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3375 return CardGeneration::expand(bytes, expand_bytes); |
|
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|
3376 } |
|
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|
3377 |
| 0 | 3378 void ConcurrentMarkSweepGeneration::expand(size_t bytes, size_t expand_bytes, |
| 3379 CMSExpansionCause::Cause cause) | |
| 3380 { | |
|
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|
3381 |
|
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|
3382 bool success = expand(bytes, expand_bytes); |
|
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3383 |
| 0 | 3384 // remember why we expanded; this information is used |
| 3385 // by shouldConcurrentCollect() when making decisions on whether to start | |
| 3386 // a new CMS cycle. | |
| 3387 if (success) { | |
| 3388 set_expansion_cause(cause); | |
| 3389 if (PrintGCDetails && Verbose) { | |
| 3390 gclog_or_tty->print_cr("Expanded CMS gen for %s", | |
| 3391 CMSExpansionCause::to_string(cause)); | |
| 3392 } | |
| 3393 } | |
| 3394 } | |
| 3395 | |
| 3396 HeapWord* ConcurrentMarkSweepGeneration::expand_and_par_lab_allocate(CMSParGCThreadState* ps, size_t word_sz) { | |
| 3397 HeapWord* res = NULL; | |
| 3398 MutexLocker x(ParGCRareEvent_lock); | |
| 3399 while (true) { | |
| 3400 // Expansion by some other thread might make alloc OK now: | |
| 3401 res = ps->lab.alloc(word_sz); | |
| 3402 if (res != NULL) return res; | |
| 3403 // If there's not enough expansion space available, give up. | |
| 3404 if (_virtual_space.uncommitted_size() < (word_sz * HeapWordSize)) { | |
| 3405 return NULL; | |
| 3406 } | |
| 3407 // Otherwise, we try expansion. | |
| 3408 expand(word_sz*HeapWordSize, MinHeapDeltaBytes, | |
| 3409 CMSExpansionCause::_allocate_par_lab); | |
| 3410 // Now go around the loop and try alloc again; | |
| 3411 // A competing par_promote might beat us to the expansion space, | |
| 3412 // so we may go around the loop again if promotion fails agaion. | |
| 3413 if (GCExpandToAllocateDelayMillis > 0) { | |
| 3414 os::sleep(Thread::current(), GCExpandToAllocateDelayMillis, false); | |
| 3415 } | |
| 3416 } | |
| 3417 } | |
| 3418 | |
| 3419 | |
| 3420 bool ConcurrentMarkSweepGeneration::expand_and_ensure_spooling_space( | |
| 3421 PromotionInfo* promo) { | |
| 3422 MutexLocker x(ParGCRareEvent_lock); | |
| 3423 size_t refill_size_bytes = promo->refillSize() * HeapWordSize; | |
| 3424 while (true) { | |
| 3425 // Expansion by some other thread might make alloc OK now: | |
| 3426 if (promo->ensure_spooling_space()) { | |
| 3427 assert(promo->has_spooling_space(), | |
| 3428 "Post-condition of successful ensure_spooling_space()"); | |
| 3429 return true; | |
| 3430 } | |
| 3431 // If there's not enough expansion space available, give up. | |
| 3432 if (_virtual_space.uncommitted_size() < refill_size_bytes) { | |
| 3433 return false; | |
| 3434 } | |
| 3435 // Otherwise, we try expansion. | |
| 3436 expand(refill_size_bytes, MinHeapDeltaBytes, | |
| 3437 CMSExpansionCause::_allocate_par_spooling_space); | |
| 3438 // Now go around the loop and try alloc again; | |
| 3439 // A competing allocation might beat us to the expansion space, | |
| 3440 // so we may go around the loop again if allocation fails again. | |
| 3441 if (GCExpandToAllocateDelayMillis > 0) { | |
| 3442 os::sleep(Thread::current(), GCExpandToAllocateDelayMillis, false); | |
| 3443 } | |
| 3444 } | |
| 3445 } | |
| 3446 | |
| 3447 | |
|
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diff
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|
3448 void ConcurrentMarkSweepGeneration::shrink_by(size_t bytes) { |
|
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8008508: CMS does not correctly reduce heap size after a Full GC
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diff
changeset
|
3449 assert_locked_or_safepoint(ExpandHeap_lock); |
|
8617e38bb4cb
8008508: CMS does not correctly reduce heap size after a Full GC
jmasa
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diff
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|
3450 // Shrink committed space |
|
8617e38bb4cb
8008508: CMS does not correctly reduce heap size after a Full GC
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|
3451 _virtual_space.shrink_by(bytes); |
|
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8008508: CMS does not correctly reduce heap size after a Full GC
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|
3452 // Shrink space; this also shrinks the space's BOT |
|
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8008508: CMS does not correctly reduce heap size after a Full GC
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|
3453 _cmsSpace->set_end((HeapWord*) _virtual_space.high()); |
|
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8008508: CMS does not correctly reduce heap size after a Full GC
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diff
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|
3454 size_t new_word_size = heap_word_size(_cmsSpace->capacity()); |
|
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8008508: CMS does not correctly reduce heap size after a Full GC
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diff
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|
3455 // Shrink the shared block offset array |
|
8617e38bb4cb
8008508: CMS does not correctly reduce heap size after a Full GC
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diff
changeset
|
3456 _bts->resize(new_word_size); |
|
8617e38bb4cb
8008508: CMS does not correctly reduce heap size after a Full GC
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|
3457 MemRegion mr(_cmsSpace->bottom(), new_word_size); |
|
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8008508: CMS does not correctly reduce heap size after a Full GC
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diff
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|
3458 // Shrink the card table |
|
8617e38bb4cb
8008508: CMS does not correctly reduce heap size after a Full GC
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diff
changeset
|
3459 Universe::heap()->barrier_set()->resize_covered_region(mr); |
|
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8008508: CMS does not correctly reduce heap size after a Full GC
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diff
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|
3460 |
|
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8008508: CMS does not correctly reduce heap size after a Full GC
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diff
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|
3461 if (Verbose && PrintGC) { |
|
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8008508: CMS does not correctly reduce heap size after a Full GC
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diff
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|
3462 size_t new_mem_size = _virtual_space.committed_size(); |
|
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diff
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|
3463 size_t old_mem_size = new_mem_size + bytes; |
|
8617e38bb4cb
8008508: CMS does not correctly reduce heap size after a Full GC
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diff
changeset
|
3464 gclog_or_tty->print_cr("Shrinking %s from " SIZE_FORMAT "K to " SIZE_FORMAT "K", |
|
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8008508: CMS does not correctly reduce heap size after a Full GC
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diff
changeset
|
3465 name(), old_mem_size/K, new_mem_size/K); |
|
8617e38bb4cb
8008508: CMS does not correctly reduce heap size after a Full GC
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|
3466 } |
|
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|
3467 } |
| 0 | 3468 |
| 3469 void ConcurrentMarkSweepGeneration::shrink(size_t bytes) { | |
| 3470 assert_locked_or_safepoint(Heap_lock); | |
| 3471 size_t size = ReservedSpace::page_align_size_down(bytes); | |
|
12112
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8022817: CMS should not shrink if compaction was not done
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diff
changeset
|
3472 // Only shrink if a compaction was done so that all the free space |
|
1bb10d3170fa
8022817: CMS should not shrink if compaction was not done
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diff
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|
3473 // in the generation is in a contiguous block at the end. |
|
1bb10d3170fa
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diff
changeset
|
3474 if (size > 0 && did_compact()) { |
| 0 | 3475 shrink_by(size); |
| 3476 } | |
| 3477 } | |
| 3478 | |
| 3479 bool ConcurrentMarkSweepGeneration::grow_by(size_t bytes) { | |
| 3480 assert_locked_or_safepoint(Heap_lock); | |
| 3481 bool result = _virtual_space.expand_by(bytes); | |
| 3482 if (result) { | |
| 3483 size_t new_word_size = | |
| 3484 heap_word_size(_virtual_space.committed_size()); | |
| 3485 MemRegion mr(_cmsSpace->bottom(), new_word_size); | |
| 3486 _bts->resize(new_word_size); // resize the block offset shared array | |
| 3487 Universe::heap()->barrier_set()->resize_covered_region(mr); | |
| 3488 // Hmmmm... why doesn't CFLS::set_end verify locking? | |
| 3489 // This is quite ugly; FIX ME XXX | |
|
1145
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6631166: CMS: better heuristics when combatting fragmentation
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1085
diff
changeset
|
3490 _cmsSpace->assert_locked(freelistLock()); |
| 0 | 3491 _cmsSpace->set_end((HeapWord*)_virtual_space.high()); |
| 3492 | |
| 3493 // update the space and generation capacity counters | |
| 3494 if (UsePerfData) { | |
| 3495 _space_counters->update_capacity(); | |
| 3496 _gen_counters->update_all(); | |
| 3497 } | |
| 3498 | |
| 3499 if (Verbose && PrintGC) { | |
| 3500 size_t new_mem_size = _virtual_space.committed_size(); | |
| 3501 size_t old_mem_size = new_mem_size - bytes; | |
|
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203f64878aab
7102489: RFE: cleanup jlong typedef on __APPLE__and _LLP64 systems.
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diff
changeset
|
3502 gclog_or_tty->print_cr("Expanding %s from " SIZE_FORMAT "K by " SIZE_FORMAT "K to " SIZE_FORMAT "K", |
| 0 | 3503 name(), old_mem_size/K, bytes/K, new_mem_size/K); |
| 3504 } | |
| 3505 } | |
| 3506 return result; | |
| 3507 } | |
| 3508 | |
| 3509 bool ConcurrentMarkSweepGeneration::grow_to_reserved() { | |
| 3510 assert_locked_or_safepoint(Heap_lock); | |
| 3511 bool success = true; | |
| 3512 const size_t remaining_bytes = _virtual_space.uncommitted_size(); | |
| 3513 if (remaining_bytes > 0) { | |
| 3514 success = grow_by(remaining_bytes); | |
| 3515 DEBUG_ONLY(if (!success) warning("grow to reserved failed");) | |
| 3516 } | |
| 3517 return success; | |
| 3518 } | |
| 3519 | |
|
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8784
diff
changeset
|
3520 void ConcurrentMarkSweepGeneration::shrink_free_list_by(size_t bytes) { |
| 0 | 3521 assert_locked_or_safepoint(Heap_lock); |
| 3522 assert_lock_strong(freelistLock()); | |
|
10180
ebded0261dfc
8012111: Remove warning about CMS generation shrinking.
jmasa
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9152
diff
changeset
|
3523 if (PrintGCDetails && Verbose) { |
|
ebded0261dfc
8012111: Remove warning about CMS generation shrinking.
jmasa
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9152
diff
changeset
|
3524 warning("Shrinking of CMS not yet implemented"); |
|
ebded0261dfc
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diff
changeset
|
3525 } |
| 0 | 3526 return; |
| 3527 } | |
| 3528 | |
| 3529 | |
| 3530 // Simple ctor/dtor wrapper for accounting & timer chores around concurrent | |
| 3531 // phases. | |
| 3532 class CMSPhaseAccounting: public StackObj { | |
| 3533 public: | |
| 3534 CMSPhaseAccounting(CMSCollector *collector, | |
| 3535 const char *phase, | |
| 3536 bool print_cr = true); | |
| 3537 ~CMSPhaseAccounting(); | |
| 3538 | |
| 3539 private: | |
| 3540 CMSCollector *_collector; | |
| 3541 const char *_phase; | |
| 3542 elapsedTimer _wallclock; | |
| 3543 bool _print_cr; | |
| 3544 | |
| 3545 public: | |
| 3546 // Not MT-safe; so do not pass around these StackObj's | |
| 3547 // where they may be accessed by other threads. | |
| 3548 jlong wallclock_millis() { | |
| 3549 assert(_wallclock.is_active(), "Wall clock should not stop"); | |
| 3550 _wallclock.stop(); // to record time | |
| 3551 jlong ret = _wallclock.milliseconds(); | |
| 3552 _wallclock.start(); // restart | |
| 3553 return ret; | |
| 3554 } | |
| 3555 }; | |
| 3556 | |
| 3557 CMSPhaseAccounting::CMSPhaseAccounting(CMSCollector *collector, | |
| 3558 const char *phase, | |
| 3559 bool print_cr) : | |
| 3560 _collector(collector), _phase(phase), _print_cr(print_cr) { | |
| 3561 | |
| 3562 if (PrintCMSStatistics != 0) { | |
| 3563 _collector->resetYields(); | |
| 3564 } | |
|
8740
62609ffa2fc6
8008684: CMS: concurrent phase start markers should always be printed
tschatzl
parents:
8736
diff
changeset
|
3565 if (PrintGCDetails) { |
| 0 | 3566 gclog_or_tty->date_stamp(PrintGCDateStamps); |
|
8740
62609ffa2fc6
8008684: CMS: concurrent phase start markers should always be printed
tschatzl
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8736
diff
changeset
|
3567 gclog_or_tty->stamp(PrintGCTimeStamps); |
|
62609ffa2fc6
8008684: CMS: concurrent phase start markers should always be printed
tschatzl
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8736
diff
changeset
|
3568 gclog_or_tty->print_cr("[%s-concurrent-%s-start]", |
| 0 | 3569 _collector->cmsGen()->short_name(), _phase); |
| 3570 } | |
| 3571 _collector->resetTimer(); | |
| 3572 _wallclock.start(); | |
| 3573 _collector->startTimer(); | |
| 3574 } | |
| 3575 | |
| 3576 CMSPhaseAccounting::~CMSPhaseAccounting() { | |
| 3577 assert(_wallclock.is_active(), "Wall clock should not have stopped"); | |
| 3578 _collector->stopTimer(); | |
| 3579 _wallclock.stop(); | |
| 3580 if (PrintGCDetails) { | |
| 3581 gclog_or_tty->date_stamp(PrintGCDateStamps); | |
|
6752
9646b7ff4d14
7198130: G1: PrintReferenceGC output comes out of order
brutisso
parents:
6725
diff
changeset
|
3582 gclog_or_tty->stamp(PrintGCTimeStamps); |
| 0 | 3583 gclog_or_tty->print("[%s-concurrent-%s: %3.3f/%3.3f secs]", |
| 3584 _collector->cmsGen()->short_name(), | |
| 3585 _phase, _collector->timerValue(), _wallclock.seconds()); | |
| 3586 if (_print_cr) { | |
|
17937
78bbf4d43a14
8037816: Fix for 8036122 breaks build with Xcode5/clang
drchase
parents:
17935
diff
changeset
|
3587 gclog_or_tty->cr(); |
| 0 | 3588 } |
| 3589 if (PrintCMSStatistics != 0) { | |
| 3590 gclog_or_tty->print_cr(" (CMS-concurrent-%s yielded %d times)", _phase, | |
| 3591 _collector->yields()); | |
| 3592 } | |
| 3593 } | |
| 3594 } | |
| 3595 | |
| 3596 // CMS work | |
| 3597 | |
| 11975 | 3598 // The common parts of CMSParInitialMarkTask and CMSParRemarkTask. |
| 3599 class CMSParMarkTask : public AbstractGangTask { | |
| 3600 protected: | |
| 3601 CMSCollector* _collector; | |
| 3602 int _n_workers; | |
| 3603 CMSParMarkTask(const char* name, CMSCollector* collector, int n_workers) : | |
| 3604 AbstractGangTask(name), | |
| 3605 _collector(collector), | |
| 3606 _n_workers(n_workers) {} | |
| 3607 // Work method in support of parallel rescan ... of young gen spaces | |
| 3608 void do_young_space_rescan(uint worker_id, OopsInGenClosure* cl, | |
| 3609 ContiguousSpace* space, | |
| 3610 HeapWord** chunk_array, size_t chunk_top); | |
| 3611 void work_on_young_gen_roots(uint worker_id, OopsInGenClosure* cl); | |
| 3612 }; | |
| 3613 | |
| 3614 // Parallel initial mark task | |
| 3615 class CMSParInitialMarkTask: public CMSParMarkTask { | |
| 3616 public: | |
| 3617 CMSParInitialMarkTask(CMSCollector* collector, int n_workers) : | |
| 3618 CMSParMarkTask("Scan roots and young gen for initial mark in parallel", | |
| 3619 collector, n_workers) {} | |
| 3620 void work(uint worker_id); | |
| 3621 }; | |
| 3622 | |
| 0 | 3623 // Checkpoint the roots into this generation from outside |
| 3624 // this generation. [Note this initial checkpoint need only | |
| 3625 // be approximate -- we'll do a catch up phase subsequently.] | |
| 3626 void CMSCollector::checkpointRootsInitial(bool asynch) { | |
| 3627 assert(_collectorState == InitialMarking, "Wrong collector state"); | |
| 3628 check_correct_thread_executing(); | |
|
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
parents:
3293
diff
changeset
|
3629 TraceCMSMemoryManagerStats tms(_collectorState,GenCollectedHeap::heap()->gc_cause()); |
|
2125
7246a374a9f2
6458402: 3 jvmti tests fail with CMS and +ExplicitGCInvokesConcurrent
kamg
parents:
1994
diff
changeset
|
3630 |
| 10405 | 3631 save_heap_summary(); |
| 3632 report_heap_summary(GCWhen::BeforeGC); | |
| 3633 | |
| 0 | 3634 ReferenceProcessor* rp = ref_processor(); |
| 3635 SpecializationStats::clear(); | |
| 3636 assert(_restart_addr == NULL, "Control point invariant"); | |
| 3637 if (asynch) { | |
| 3638 // acquire locks for subsequent manipulations | |
| 3639 MutexLockerEx x(bitMapLock(), | |
| 3640 Mutex::_no_safepoint_check_flag); | |
| 3641 checkpointRootsInitialWork(asynch); | |
|
3979
4dfb2df418f2
6484982: G1: process references during evacuation pauses
johnc
parents:
3827
diff
changeset
|
3642 // enable ("weak") refs discovery |
|
4dfb2df418f2
6484982: G1: process references during evacuation pauses
johnc
parents:
3827
diff
changeset
|
3643 rp->enable_discovery(true /*verify_disabled*/, true /*check_no_refs*/); |
| 0 | 3644 _collectorState = Marking; |
| 3645 } else { | |
| 3646 // (Weak) Refs discovery: this is controlled from genCollectedHeap::do_collection | |
| 3647 // which recognizes if we are a CMS generation, and doesn't try to turn on | |
| 3648 // discovery; verify that they aren't meddling. | |
| 3649 assert(!rp->discovery_is_atomic(), | |
| 3650 "incorrect setting of discovery predicate"); | |
| 3651 assert(!rp->discovery_enabled(), "genCollectedHeap shouldn't control " | |
| 3652 "ref discovery for this generation kind"); | |
| 3653 // already have locks | |
| 3654 checkpointRootsInitialWork(asynch); | |
|
3979
4dfb2df418f2
6484982: G1: process references during evacuation pauses
johnc
parents:
3827
diff
changeset
|
3655 // now enable ("weak") refs discovery |
|
4dfb2df418f2
6484982: G1: process references during evacuation pauses
johnc
parents:
3827
diff
changeset
|
3656 rp->enable_discovery(true /*verify_disabled*/, false /*verify_no_refs*/); |
| 0 | 3657 _collectorState = Marking; |
| 3658 } | |
| 3659 SpecializationStats::print(); | |
| 3660 } | |
| 3661 | |
| 3662 void CMSCollector::checkpointRootsInitialWork(bool asynch) { | |
| 3663 assert(SafepointSynchronize::is_at_safepoint(), "world should be stopped"); | |
| 3664 assert(_collectorState == InitialMarking, "just checking"); | |
| 3665 | |
| 3666 // If there has not been a GC[n-1] since last GC[n] cycle completed, | |
| 3667 // precede our marking with a collection of all | |
| 3668 // younger generations to keep floating garbage to a minimum. | |
| 3669 // XXX: we won't do this for now -- it's an optimization to be done later. | |
| 3670 | |
| 3671 // already have locks | |
| 3672 assert_lock_strong(bitMapLock()); | |
| 3673 assert(_markBitMap.isAllClear(), "was reset at end of previous cycle"); | |
| 3674 | |
| 3675 // Setup the verification and class unloading state for this | |
| 3676 // CMS collection cycle. | |
| 3677 setup_cms_unloading_and_verification_state(); | |
| 3678 | |
| 10405 | 3679 NOT_PRODUCT(GCTraceTime t("\ncheckpointRootsInitialWork", |
| 3680 PrintGCDetails && Verbose, true, _gc_timer_cm);) | |
| 0 | 3681 if (UseAdaptiveSizePolicy) { |
| 3682 size_policy()->checkpoint_roots_initial_begin(); | |
| 3683 } | |
| 3684 | |
| 3685 // Reset all the PLAB chunk arrays if necessary. | |
| 3686 if (_survivor_plab_array != NULL && !CMSPLABRecordAlways) { | |
| 3687 reset_survivor_plab_arrays(); | |
| 3688 } | |
| 3689 | |
| 3690 ResourceMark rm; | |
| 3691 HandleMark hm; | |
| 3692 | |
| 3693 FalseClosure falseClosure; | |
| 3694 // In the case of a synchronous collection, we will elide the | |
| 3695 // remark step, so it's important to catch all the nmethod oops | |
|
994
753cf9794df9
6885169: merge of 4957990 and 6863023 causes conflict on do_nmethods
jrose
parents:
993
diff
changeset
|
3696 // in this step. |
|
753cf9794df9
6885169: merge of 4957990 and 6863023 causes conflict on do_nmethods
jrose
parents:
993
diff
changeset
|
3697 // The final 'true' flag to gen_process_strong_roots will ensure this. |
|
753cf9794df9
6885169: merge of 4957990 and 6863023 causes conflict on do_nmethods
jrose
parents:
993
diff
changeset
|
3698 // If 'async' is true, we can relax the nmethod tracing. |
|
753cf9794df9
6885169: merge of 4957990 and 6863023 causes conflict on do_nmethods
jrose
parents:
993
diff
changeset
|
3699 MarkRefsIntoClosure notOlder(_span, &_markBitMap); |
| 0 | 3700 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
| 3701 | |
| 3702 verify_work_stacks_empty(); | |
| 3703 verify_overflow_empty(); | |
| 3704 | |
| 3705 gch->ensure_parsability(false); // fill TLABs, but no need to retire them | |
| 3706 // Update the saved marks which may affect the root scans. | |
| 3707 gch->save_marks(); | |
| 3708 | |
| 3709 // weak reference processing has not started yet. | |
| 3710 ref_processor()->set_enqueuing_is_done(false); | |
| 3711 | |
|
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da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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6197
diff
changeset
|
3712 // Need to remember all newly created CLDs, |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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6197
diff
changeset
|
3713 // so that we can guarantee that the remark finds them. |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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6197
diff
changeset
|
3714 ClassLoaderDataGraph::remember_new_clds(true); |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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6197
diff
changeset
|
3715 |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
3716 // Whenever a CLD is found, it will be claimed before proceeding to mark |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
3717 // the klasses. The claimed marks need to be cleared before marking starts. |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
3718 ClassLoaderDataGraph::clear_claimed_marks(); |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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6197
diff
changeset
|
3719 |
|
11973
7b06ae405d7b
6990419: CMS Remaining work for 6572569: consistently skewed work distribution in (long) re-mark pauses
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11096
diff
changeset
|
3720 if (CMSPrintEdenSurvivorChunks) { |
|
7b06ae405d7b
6990419: CMS Remaining work for 6572569: consistently skewed work distribution in (long) re-mark pauses
jmasa
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11096
diff
changeset
|
3721 print_eden_and_survivor_chunk_arrays(); |
|
7b06ae405d7b
6990419: CMS Remaining work for 6572569: consistently skewed work distribution in (long) re-mark pauses
jmasa
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11096
diff
changeset
|
3722 } |
|
7b06ae405d7b
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11096
diff
changeset
|
3723 |
| 0 | 3724 { |
| 3725 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact;) | |
| 11975 | 3726 if (CMSParallelInitialMarkEnabled && CollectedHeap::use_parallel_gc_threads()) { |
| 3727 // The parallel version. | |
| 3728 FlexibleWorkGang* workers = gch->workers(); | |
| 3729 assert(workers != NULL, "Need parallel worker threads."); | |
| 3730 int n_workers = workers->active_workers(); | |
| 3731 CMSParInitialMarkTask tsk(this, n_workers); | |
| 3732 gch->set_par_threads(n_workers); | |
| 3733 initialize_sequential_subtasks_for_young_gen_rescan(n_workers); | |
| 3734 if (n_workers > 1) { | |
| 3735 GenCollectedHeap::StrongRootsScope srs(gch); | |
| 3736 workers->run_task(&tsk); | |
| 3737 } else { | |
| 3738 GenCollectedHeap::StrongRootsScope srs(gch); | |
| 3739 tsk.work(0); | |
| 3740 } | |
| 3741 gch->set_par_threads(0); | |
| 3742 } else { | |
| 3743 // The serial version. | |
| 3744 CMKlassClosure klass_closure(¬Older); | |
| 3745 gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel. | |
| 3746 gch->gen_process_strong_roots(_cmsGen->level(), | |
| 3747 true, // younger gens are roots | |
| 3748 true, // activate StrongRootsScope | |
| 3749 false, // not scavenging | |
| 3750 SharedHeap::ScanningOption(roots_scanning_options()), | |
| 3751 ¬Older, | |
| 3752 true, // walk all of code cache if (so & SO_CodeCache) | |
| 3753 NULL, | |
| 3754 &klass_closure); | |
| 3755 } | |
| 0 | 3756 } |
| 3757 | |
| 3758 // Clear mod-union table; it will be dirtied in the prologue of | |
| 3759 // CMS generation per each younger generation collection. | |
| 3760 | |
| 3761 assert(_modUnionTable.isAllClear(), | |
| 3762 "Was cleared in most recent final checkpoint phase" | |
| 3763 " or no bits are set in the gc_prologue before the start of the next " | |
| 3764 "subsequent marking phase."); | |
| 3765 | |
|
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3766 assert(_ct->klass_rem_set()->mod_union_is_clear(), "Must be"); |
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3767 |
| 0 | 3768 // Save the end of the used_region of the constituent generations |
| 3769 // to be used to limit the extent of sweep in each generation. | |
| 3770 save_sweep_limits(); | |
| 3771 if (UseAdaptiveSizePolicy) { | |
| 3772 size_policy()->checkpoint_roots_initial_end(gch->gc_cause()); | |
| 3773 } | |
| 3774 verify_overflow_empty(); | |
| 3775 } | |
| 3776 | |
| 3777 bool CMSCollector::markFromRoots(bool asynch) { | |
| 3778 // we might be tempted to assert that: | |
| 3779 // assert(asynch == !SafepointSynchronize::is_at_safepoint(), | |
| 3780 // "inconsistent argument?"); | |
| 3781 // However that wouldn't be right, because it's possible that | |
| 3782 // a safepoint is indeed in progress as a younger generation | |
| 3783 // stop-the-world GC happens even as we mark in this generation. | |
| 3784 assert(_collectorState == Marking, "inconsistent state?"); | |
| 3785 check_correct_thread_executing(); | |
| 3786 verify_overflow_empty(); | |
| 3787 | |
| 3788 bool res; | |
| 3789 if (asynch) { | |
| 3790 | |
| 3791 // Start the timers for adaptive size policy for the concurrent phases | |
| 3792 // Do it here so that the foreground MS can use the concurrent | |
| 3793 // timer since a foreground MS might has the sweep done concurrently | |
| 3794 // or STW. | |
| 3795 if (UseAdaptiveSizePolicy) { | |
| 3796 size_policy()->concurrent_marking_begin(); | |
| 3797 } | |
| 3798 | |
| 3799 // Weak ref discovery note: We may be discovering weak | |
| 3800 // refs in this generation concurrent (but interleaved) with | |
| 3801 // weak ref discovery by a younger generation collector. | |
| 3802 | |
| 3803 CMSTokenSyncWithLocks ts(true, bitMapLock()); | |
| 3804 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
| 3805 CMSPhaseAccounting pa(this, "mark", !PrintGCDetails); | |
| 3806 res = markFromRootsWork(asynch); | |
| 3807 if (res) { | |
| 3808 _collectorState = Precleaning; | |
| 3809 } else { // We failed and a foreground collection wants to take over | |
| 3810 assert(_foregroundGCIsActive, "internal state inconsistency"); | |
| 3811 assert(_restart_addr == NULL, "foreground will restart from scratch"); | |
| 3812 if (PrintGCDetails) { | |
| 3813 gclog_or_tty->print_cr("bailing out to foreground collection"); | |
| 3814 } | |
| 3815 } | |
| 3816 if (UseAdaptiveSizePolicy) { | |
| 3817 size_policy()->concurrent_marking_end(); | |
| 3818 } | |
| 3819 } else { | |
| 3820 assert(SafepointSynchronize::is_at_safepoint(), | |
| 3821 "inconsistent with asynch == false"); | |
| 3822 if (UseAdaptiveSizePolicy) { | |
| 3823 size_policy()->ms_collection_marking_begin(); | |
| 3824 } | |
| 3825 // already have locks | |
| 3826 res = markFromRootsWork(asynch); | |
| 3827 _collectorState = FinalMarking; | |
| 3828 if (UseAdaptiveSizePolicy) { | |
| 3829 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 3830 size_policy()->ms_collection_marking_end(gch->gc_cause()); | |
| 3831 } | |
| 3832 } | |
| 3833 verify_overflow_empty(); | |
| 3834 return res; | |
| 3835 } | |
| 3836 | |
| 3837 bool CMSCollector::markFromRootsWork(bool asynch) { | |
| 3838 // iterate over marked bits in bit map, doing a full scan and mark | |
| 3839 // from these roots using the following algorithm: | |
| 3840 // . if oop is to the right of the current scan pointer, | |
| 3841 // mark corresponding bit (we'll process it later) | |
| 3842 // . else (oop is to left of current scan pointer) | |
| 3843 // push oop on marking stack | |
| 3844 // . drain the marking stack | |
| 3845 | |
| 3846 // Note that when we do a marking step we need to hold the | |
| 3847 // bit map lock -- recall that direct allocation (by mutators) | |
| 3848 // and promotion (by younger generation collectors) is also | |
| 3849 // marking the bit map. [the so-called allocate live policy.] | |
| 3850 // Because the implementation of bit map marking is not | |
| 3851 // robust wrt simultaneous marking of bits in the same word, | |
| 3852 // we need to make sure that there is no such interference | |
| 3853 // between concurrent such updates. | |
| 3854 | |
| 3855 // already have locks | |
| 3856 assert_lock_strong(bitMapLock()); | |
| 3857 | |
| 3858 verify_work_stacks_empty(); | |
| 3859 verify_overflow_empty(); | |
| 3860 bool result = false; | |
| 1284 | 3861 if (CMSConcurrentMTEnabled && ConcGCThreads > 0) { |
| 0 | 3862 result = do_marking_mt(asynch); |
| 3863 } else { | |
| 3864 result = do_marking_st(asynch); | |
| 3865 } | |
| 3866 return result; | |
| 3867 } | |
| 3868 | |
| 3869 // Forward decl | |
| 3870 class CMSConcMarkingTask; | |
| 3871 | |
| 3872 class CMSConcMarkingTerminator: public ParallelTaskTerminator { | |
| 3873 CMSCollector* _collector; | |
| 3874 CMSConcMarkingTask* _task; | |
|
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3875 public: |
| 0 | 3876 virtual void yield(); |
|
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3877 |
| 0 | 3878 // "n_threads" is the number of threads to be terminated. |
| 3879 // "queue_set" is a set of work queues of other threads. | |
| 3880 // "collector" is the CMS collector associated with this task terminator. | |
| 3881 // "yield" indicates whether we need the gang as a whole to yield. | |
|
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3882 CMSConcMarkingTerminator(int n_threads, TaskQueueSetSuper* queue_set, CMSCollector* collector) : |
| 0 | 3883 ParallelTaskTerminator(n_threads, queue_set), |
|
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3884 _collector(collector) { } |
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3885 |
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3886 void set_task(CMSConcMarkingTask* task) { |
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3887 _task = task; |
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3888 } |
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3889 }; |
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3890 |
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3891 class CMSConcMarkingTerminatorTerminator: public TerminatorTerminator { |
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3892 CMSConcMarkingTask* _task; |
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3893 public: |
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3894 bool should_exit_termination(); |
| 0 | 3895 void set_task(CMSConcMarkingTask* task) { |
| 3896 _task = task; | |
| 3897 } | |
| 3898 }; | |
| 3899 | |
| 3900 // MT Concurrent Marking Task | |
| 3901 class CMSConcMarkingTask: public YieldingFlexibleGangTask { | |
| 3902 CMSCollector* _collector; | |
| 3903 int _n_workers; // requested/desired # workers | |
| 3904 bool _asynch; | |
| 3905 bool _result; | |
| 3906 CompactibleFreeListSpace* _cms_space; | |
|
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3907 char _pad_front[64]; // padding to ... |
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3908 HeapWord* _global_finger; // ... avoid sharing cache line |
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3909 char _pad_back[64]; |
|
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3910 HeapWord* _restart_addr; |
| 0 | 3911 |
| 3912 // Exposed here for yielding support | |
| 3913 Mutex* const _bit_map_lock; | |
| 3914 | |
| 3915 // The per thread work queues, available here for stealing | |
| 3916 OopTaskQueueSet* _task_queues; | |
|
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3917 |
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3918 // Termination (and yielding) support |
| 0 | 3919 CMSConcMarkingTerminator _term; |
|
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3920 CMSConcMarkingTerminatorTerminator _term_term; |
| 0 | 3921 |
| 3922 public: | |
| 3923 CMSConcMarkingTask(CMSCollector* collector, | |
| 3924 CompactibleFreeListSpace* cms_space, | |
|
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3925 bool asynch, |
| 0 | 3926 YieldingFlexibleWorkGang* workers, |
| 3927 OopTaskQueueSet* task_queues): | |
| 3928 YieldingFlexibleGangTask("Concurrent marking done multi-threaded"), | |
| 3929 _collector(collector), | |
| 3930 _cms_space(cms_space), | |
|
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3931 _asynch(asynch), _n_workers(0), _result(true), |
|
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3932 _task_queues(task_queues), |
|
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3933 _term(_n_workers, task_queues, _collector), |
| 0 | 3934 _bit_map_lock(collector->bitMapLock()) |
| 3935 { | |
|
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3936 _requested_size = _n_workers; |
| 0 | 3937 _term.set_task(this); |
|
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3938 _term_term.set_task(this); |
|
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3939 _restart_addr = _global_finger = _cms_space->bottom(); |
| 0 | 3940 } |
| 3941 | |
| 3942 | |
| 3943 OopTaskQueueSet* task_queues() { return _task_queues; } | |
| 3944 | |
| 3945 OopTaskQueue* work_queue(int i) { return task_queues()->queue(i); } | |
| 3946 | |
| 3947 HeapWord** global_finger_addr() { return &_global_finger; } | |
| 3948 | |
| 3949 CMSConcMarkingTerminator* terminator() { return &_term; } | |
| 3950 | |
|
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3951 virtual void set_for_termination(int active_workers) { |
|
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3952 terminator()->reset_for_reuse(active_workers); |
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3953 } |
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3954 |
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3955 void work(uint worker_id); |
|
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3956 bool should_yield() { |
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3957 return ConcurrentMarkSweepThread::should_yield() |
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3958 && !_collector->foregroundGCIsActive() |
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3959 && _asynch; |
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3960 } |
| 0 | 3961 |
| 3962 virtual void coordinator_yield(); // stuff done by coordinator | |
| 3963 bool result() { return _result; } | |
| 3964 | |
| 3965 void reset(HeapWord* ra) { | |
|
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3966 assert(_global_finger >= _cms_space->end(), "Postcondition of ::work(i)"); |
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3967 _restart_addr = _global_finger = ra; |
| 0 | 3968 _term.reset_for_reuse(); |
| 3969 } | |
| 3970 | |
| 3971 static bool get_work_from_overflow_stack(CMSMarkStack* ovflw_stk, | |
| 3972 OopTaskQueue* work_q); | |
| 3973 | |
| 3974 private: | |
| 3975 void do_scan_and_mark(int i, CompactibleFreeListSpace* sp); | |
| 3976 void do_work_steal(int i); | |
| 3977 void bump_global_finger(HeapWord* f); | |
| 3978 }; | |
| 3979 | |
|
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3980 bool CMSConcMarkingTerminatorTerminator::should_exit_termination() { |
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3981 assert(_task != NULL, "Error"); |
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3982 return _task->yielding(); |
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3983 // Note that we do not need the disjunct || _task->should_yield() above |
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3984 // because we want terminating threads to yield only if the task |
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3985 // is already in the midst of yielding, which happens only after at least one |
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3986 // thread has yielded. |
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3987 } |
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3988 |
| 0 | 3989 void CMSConcMarkingTerminator::yield() { |
|
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3990 if (_task->should_yield()) { |
| 0 | 3991 _task->yield(); |
| 3992 } else { | |
| 3993 ParallelTaskTerminator::yield(); | |
| 3994 } | |
| 3995 } | |
| 3996 | |
| 3997 //////////////////////////////////////////////////////////////// | |
| 3998 // Concurrent Marking Algorithm Sketch | |
| 3999 //////////////////////////////////////////////////////////////// | |
| 4000 // Until all tasks exhausted (both spaces): | |
| 4001 // -- claim next available chunk | |
| 4002 // -- bump global finger via CAS | |
| 4003 // -- find first object that starts in this chunk | |
| 4004 // and start scanning bitmap from that position | |
| 4005 // -- scan marked objects for oops | |
| 4006 // -- CAS-mark target, and if successful: | |
| 4007 // . if target oop is above global finger (volatile read) | |
| 4008 // nothing to do | |
| 4009 // . if target oop is in chunk and above local finger | |
| 4010 // then nothing to do | |
| 4011 // . else push on work-queue | |
| 4012 // -- Deal with possible overflow issues: | |
| 4013 // . local work-queue overflow causes stuff to be pushed on | |
| 4014 // global (common) overflow queue | |
| 4015 // . always first empty local work queue | |
| 4016 // . then get a batch of oops from global work queue if any | |
| 4017 // . then do work stealing | |
| 4018 // -- When all tasks claimed (both spaces) | |
| 4019 // and local work queue empty, | |
| 4020 // then in a loop do: | |
| 4021 // . check global overflow stack; steal a batch of oops and trace | |
| 4022 // . try to steal from other threads oif GOS is empty | |
| 4023 // . if neither is available, offer termination | |
| 4024 // -- Terminate and return result | |
| 4025 // | |
|
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4026 void CMSConcMarkingTask::work(uint worker_id) { |
| 0 | 4027 elapsedTimer _timer; |
| 4028 ResourceMark rm; | |
| 4029 HandleMark hm; | |
| 4030 | |
| 4031 DEBUG_ONLY(_collector->verify_overflow_empty();) | |
| 4032 | |
| 4033 // Before we begin work, our work queue should be empty | |
|
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4034 assert(work_queue(worker_id)->size() == 0, "Expected to be empty"); |
| 0 | 4035 // Scan the bitmap covering _cms_space, tracing through grey objects. |
| 4036 _timer.start(); | |
|
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4037 do_scan_and_mark(worker_id, _cms_space); |
| 0 | 4038 _timer.stop(); |
| 4039 if (PrintCMSStatistics != 0) { | |
| 4040 gclog_or_tty->print_cr("Finished cms space scanning in %dth thread: %3.3f sec", | |
|
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4041 worker_id, _timer.seconds()); |
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4042 // XXX: need xxx/xxx type of notation, two timers |
| 0 | 4043 } |
| 4044 | |
| 4045 // ... do work stealing | |
| 4046 _timer.reset(); | |
| 4047 _timer.start(); | |
|
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4048 do_work_steal(worker_id); |
| 0 | 4049 _timer.stop(); |
| 4050 if (PrintCMSStatistics != 0) { | |
| 4051 gclog_or_tty->print_cr("Finished work stealing in %dth thread: %3.3f sec", | |
|
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4052 worker_id, _timer.seconds()); |
|
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4053 // XXX: need xxx/xxx type of notation, two timers |
| 0 | 4054 } |
| 4055 assert(_collector->_markStack.isEmpty(), "Should have been emptied"); | |
|
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4056 assert(work_queue(worker_id)->size() == 0, "Should have been emptied"); |
| 0 | 4057 // Note that under the current task protocol, the |
| 4058 // following assertion is true even of the spaces | |
| 4059 // expanded since the completion of the concurrent | |
| 4060 // marking. XXX This will likely change under a strict | |
| 4061 // ABORT semantics. | |
|
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4062 // After perm removal the comparison was changed to |
|
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4063 // greater than or equal to from strictly greater than. |
|
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4064 // Before perm removal the highest address sweep would |
|
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4065 // have been at the end of perm gen but now is at the |
|
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4066 // end of the tenured gen. |
|
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4067 assert(_global_finger >= _cms_space->end(), |
| 0 | 4068 "All tasks have been completed"); |
| 4069 DEBUG_ONLY(_collector->verify_overflow_empty();) | |
| 4070 } | |
| 4071 | |
| 4072 void CMSConcMarkingTask::bump_global_finger(HeapWord* f) { | |
| 4073 HeapWord* read = _global_finger; | |
| 4074 HeapWord* cur = read; | |
| 4075 while (f > read) { | |
| 4076 cur = read; | |
| 4077 read = (HeapWord*) Atomic::cmpxchg_ptr(f, &_global_finger, cur); | |
| 4078 if (cur == read) { | |
| 4079 // our cas succeeded | |
| 4080 assert(_global_finger >= f, "protocol consistency"); | |
| 4081 break; | |
| 4082 } | |
| 4083 } | |
| 4084 } | |
| 4085 | |
| 4086 // This is really inefficient, and should be redone by | |
| 4087 // using (not yet available) block-read and -write interfaces to the | |
| 4088 // stack and the work_queue. XXX FIX ME !!! | |
| 4089 bool CMSConcMarkingTask::get_work_from_overflow_stack(CMSMarkStack* ovflw_stk, | |
| 4090 OopTaskQueue* work_q) { | |
| 4091 // Fast lock-free check | |
| 4092 if (ovflw_stk->length() == 0) { | |
| 4093 return false; | |
| 4094 } | |
| 4095 assert(work_q->size() == 0, "Shouldn't steal"); | |
| 4096 MutexLockerEx ml(ovflw_stk->par_lock(), | |
| 4097 Mutex::_no_safepoint_check_flag); | |
| 4098 // Grab up to 1/4 the size of the work queue | |
|
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|
4099 size_t num = MIN2((size_t)(work_q->max_elems() - work_q->size())/4, |
| 0 | 4100 (size_t)ParGCDesiredObjsFromOverflowList); |
| 4101 num = MIN2(num, ovflw_stk->length()); | |
| 4102 for (int i = (int) num; i > 0; i--) { | |
| 4103 oop cur = ovflw_stk->pop(); | |
| 4104 assert(cur != NULL, "Counted wrong?"); | |
| 4105 work_q->push(cur); | |
| 4106 } | |
| 4107 return num > 0; | |
| 4108 } | |
| 4109 | |
| 4110 void CMSConcMarkingTask::do_scan_and_mark(int i, CompactibleFreeListSpace* sp) { | |
| 4111 SequentialSubTasksDone* pst = sp->conc_par_seq_tasks(); | |
| 4112 int n_tasks = pst->n_tasks(); | |
| 4113 // We allow that there may be no tasks to do here because | |
| 4114 // we are restarting after a stack overflow. | |
|
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4115 assert(pst->valid() || n_tasks == 0, "Uninitialized use?"); |
|
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4116 uint nth_task = 0; |
| 0 | 4117 |
|
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4118 HeapWord* aligned_start = sp->bottom(); |
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4119 if (sp->used_region().contains(_restart_addr)) { |
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4120 // Align down to a card boundary for the start of 0th task |
|
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4121 // for this space. |
|
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4122 aligned_start = |
|
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4123 (HeapWord*)align_size_down((uintptr_t)_restart_addr, |
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4124 CardTableModRefBS::card_size); |
|
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4125 } |
|
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4126 |
| 0 | 4127 size_t chunk_size = sp->marking_task_size(); |
| 4128 while (!pst->is_task_claimed(/* reference */ nth_task)) { | |
| 4129 // Having claimed the nth task in this space, | |
| 4130 // compute the chunk that it corresponds to: | |
|
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4131 MemRegion span = MemRegion(aligned_start + nth_task*chunk_size, |
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4132 aligned_start + (nth_task+1)*chunk_size); |
| 0 | 4133 // Try and bump the global finger via a CAS; |
| 4134 // note that we need to do the global finger bump | |
| 4135 // _before_ taking the intersection below, because | |
| 4136 // the task corresponding to that region will be | |
| 4137 // deemed done even if the used_region() expands | |
| 4138 // because of allocation -- as it almost certainly will | |
| 4139 // during start-up while the threads yield in the | |
| 4140 // closure below. | |
| 4141 HeapWord* finger = span.end(); | |
| 4142 bump_global_finger(finger); // atomically | |
| 4143 // There are null tasks here corresponding to chunks | |
| 4144 // beyond the "top" address of the space. | |
| 4145 span = span.intersection(sp->used_region()); | |
| 4146 if (!span.is_empty()) { // Non-null task | |
|
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4147 HeapWord* prev_obj; |
|
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4148 assert(!span.contains(_restart_addr) || nth_task == 0, |
|
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4149 "Inconsistency"); |
|
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4150 if (nth_task == 0) { |
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4151 // For the 0th task, we'll not need to compute a block_start. |
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4152 if (span.contains(_restart_addr)) { |
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4153 // In the case of a restart because of stack overflow, |
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4154 // we might additionally skip a chunk prefix. |
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4155 prev_obj = _restart_addr; |
| 0 | 4156 } else { |
|
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4157 prev_obj = span.start(); |
|
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|
4158 } |
|
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4159 } else { |
|
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|
4160 // We want to skip the first object because |
|
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|
4161 // the protocol is to scan any object in its entirety |
|
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|
4162 // that _starts_ in this span; a fortiori, any |
|
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4163 // object starting in an earlier span is scanned |
|
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|
4164 // as part of an earlier claimed task. |
|
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4165 // Below we use the "careful" version of block_start |
|
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4166 // so we do not try to navigate uninitialized objects. |
|
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|
4167 prev_obj = sp->block_start_careful(span.start()); |
|
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4168 // Below we use a variant of block_size that uses the |
|
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|
4169 // Printezis bits to avoid waiting for allocated |
|
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|
4170 // objects to become initialized/parsable. |
|
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|
4171 while (prev_obj < span.start()) { |
|
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4172 size_t sz = sp->block_size_no_stall(prev_obj, _collector); |
|
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4173 if (sz > 0) { |
|
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|
4174 prev_obj += sz; |
|
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|
4175 } else { |
|
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|
4176 // In this case we may end up doing a bit of redundant |
|
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|
4177 // scanning, but that appears unavoidable, short of |
|
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|
4178 // locking the free list locks; see bug 6324141. |
|
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|
4179 break; |
|
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|
4180 } |
| 0 | 4181 } |
| 4182 } | |
| 4183 if (prev_obj < span.end()) { | |
| 4184 MemRegion my_span = MemRegion(prev_obj, span.end()); | |
| 4185 // Do the marking work within a non-empty span -- | |
| 4186 // the last argument to the constructor indicates whether the | |
| 4187 // iteration should be incremental with periodic yields. | |
| 4188 Par_MarkFromRootsClosure cl(this, _collector, my_span, | |
| 4189 &_collector->_markBitMap, | |
| 4190 work_queue(i), | |
| 4191 &_collector->_markStack, | |
| 4192 _asynch); | |
| 4193 _collector->_markBitMap.iterate(&cl, my_span.start(), my_span.end()); | |
| 4194 } // else nothing to do for this task | |
| 4195 } // else nothing to do for this task | |
| 4196 } | |
| 4197 // We'd be tempted to assert here that since there are no | |
| 4198 // more tasks left to claim in this space, the global_finger | |
| 4199 // must exceed space->top() and a fortiori space->end(). However, | |
| 4200 // that would not quite be correct because the bumping of | |
| 4201 // global_finger occurs strictly after the claiming of a task, | |
| 4202 // so by the time we reach here the global finger may not yet | |
| 4203 // have been bumped up by the thread that claimed the last | |
| 4204 // task. | |
| 4205 pst->all_tasks_completed(); | |
| 4206 } | |
| 4207 | |
|
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4208 class Par_ConcMarkingClosure: public CMSOopClosure { |
|
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|
4209 private: |
|
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|
4210 CMSCollector* _collector; |
|
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|
4211 CMSConcMarkingTask* _task; |
| 0 | 4212 MemRegion _span; |
| 4213 CMSBitMap* _bit_map; | |
| 4214 CMSMarkStack* _overflow_stack; | |
| 4215 OopTaskQueue* _work_queue; | |
|
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4216 protected: |
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4217 DO_OOP_WORK_DEFN |
| 0 | 4218 public: |
|
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|
4219 Par_ConcMarkingClosure(CMSCollector* collector, CMSConcMarkingTask* task, OopTaskQueue* work_queue, |
|
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4220 CMSBitMap* bit_map, CMSMarkStack* overflow_stack): |
|
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|
4221 CMSOopClosure(collector->ref_processor()), |
|
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|
4222 _collector(collector), |
|
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|
4223 _task(task), |
|
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|
4224 _span(collector->_span), |
| 0 | 4225 _work_queue(work_queue), |
| 4226 _bit_map(bit_map), | |
| 935 | 4227 _overflow_stack(overflow_stack) |
| 4228 { } | |
|
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4229 virtual void do_oop(oop* p); |
|
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|
4230 virtual void do_oop(narrowOop* p); |
|
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4231 |
| 0 | 4232 void trim_queue(size_t max); |
| 4233 void handle_stack_overflow(HeapWord* lost); | |
|
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|
4234 void do_yield_check() { |
|
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|
4235 if (_task->should_yield()) { |
|
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|
4236 _task->yield(); |
|
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|
4237 } |
|
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|
4238 } |
| 0 | 4239 }; |
| 4240 | |
|
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|
4241 // Grey object scanning during work stealing phase -- |
|
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|
4242 // the salient assumption here is that any references |
|
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4243 // that are in these stolen objects being scanned must |
|
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|
4244 // already have been initialized (else they would not have |
|
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|
4245 // been published), so we do not need to check for |
|
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|
4246 // uninitialized objects before pushing here. |
|
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4247 void Par_ConcMarkingClosure::do_oop(oop obj) { |
|
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|
4248 assert(obj->is_oop_or_null(true), "expected an oop or NULL"); |
|
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|
4249 HeapWord* addr = (HeapWord*)obj; |
| 0 | 4250 // Check if oop points into the CMS generation |
| 4251 // and is not marked | |
| 4252 if (_span.contains(addr) && !_bit_map->isMarked(addr)) { | |
| 4253 // a white object ... | |
| 4254 // If we manage to "claim" the object, by being the | |
| 4255 // first thread to mark it, then we push it on our | |
| 4256 // marking stack | |
| 4257 if (_bit_map->par_mark(addr)) { // ... now grey | |
| 4258 // push on work queue (grey set) | |
| 4259 bool simulate_overflow = false; | |
| 4260 NOT_PRODUCT( | |
| 4261 if (CMSMarkStackOverflowALot && | |
| 4262 _collector->simulate_overflow()) { | |
| 4263 // simulate a stack overflow | |
| 4264 simulate_overflow = true; | |
| 4265 } | |
| 4266 ) | |
| 4267 if (simulate_overflow || | |
|
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4268 !(_work_queue->push(obj) || _overflow_stack->par_push(obj))) { |
| 0 | 4269 // stack overflow |
| 4270 if (PrintCMSStatistics != 0) { | |
| 4271 gclog_or_tty->print_cr("CMS marking stack overflow (benign) at " | |
| 4272 SIZE_FORMAT, _overflow_stack->capacity()); | |
| 4273 } | |
| 4274 // We cannot assert that the overflow stack is full because | |
| 4275 // it may have been emptied since. | |
| 4276 assert(simulate_overflow || | |
| 4277 _work_queue->size() == _work_queue->max_elems(), | |
| 4278 "Else push should have succeeded"); | |
| 4279 handle_stack_overflow(addr); | |
| 4280 } | |
| 4281 } // Else, some other thread got there first | |
|
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4282 do_yield_check(); |
| 0 | 4283 } |
| 4284 } | |
| 4285 | |
|
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4286 void Par_ConcMarkingClosure::do_oop(oop* p) { Par_ConcMarkingClosure::do_oop_work(p); } |
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4287 void Par_ConcMarkingClosure::do_oop(narrowOop* p) { Par_ConcMarkingClosure::do_oop_work(p); } |
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4288 |
| 0 | 4289 void Par_ConcMarkingClosure::trim_queue(size_t max) { |
| 4290 while (_work_queue->size() > max) { | |
| 4291 oop new_oop; | |
| 4292 if (_work_queue->pop_local(new_oop)) { | |
| 4293 assert(new_oop->is_oop(), "Should be an oop"); | |
| 4294 assert(_bit_map->isMarked((HeapWord*)new_oop), "Grey object"); | |
| 4295 assert(_span.contains((HeapWord*)new_oop), "Not in span"); | |
| 4296 new_oop->oop_iterate(this); // do_oop() above | |
|
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|
4297 do_yield_check(); |
| 0 | 4298 } |
| 4299 } | |
| 4300 } | |
| 4301 | |
| 4302 // Upon stack overflow, we discard (part of) the stack, | |
| 4303 // remembering the least address amongst those discarded | |
| 4304 // in CMSCollector's _restart_address. | |
| 4305 void Par_ConcMarkingClosure::handle_stack_overflow(HeapWord* lost) { | |
| 4306 // We need to do this under a mutex to prevent other | |
|
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4307 // workers from interfering with the work done below. |
| 0 | 4308 MutexLockerEx ml(_overflow_stack->par_lock(), |
| 4309 Mutex::_no_safepoint_check_flag); | |
| 4310 // Remember the least grey address discarded | |
| 4311 HeapWord* ra = (HeapWord*)_overflow_stack->least_value(lost); | |
| 4312 _collector->lower_restart_addr(ra); | |
| 4313 _overflow_stack->reset(); // discard stack contents | |
| 4314 _overflow_stack->expand(); // expand the stack if possible | |
| 4315 } | |
| 4316 | |
| 4317 | |
| 4318 void CMSConcMarkingTask::do_work_steal(int i) { | |
| 4319 OopTaskQueue* work_q = work_queue(i); | |
| 4320 oop obj_to_scan; | |
| 4321 CMSBitMap* bm = &(_collector->_markBitMap); | |
| 4322 CMSMarkStack* ovflw = &(_collector->_markStack); | |
| 4323 int* seed = _collector->hash_seed(i); | |
|
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4324 Par_ConcMarkingClosure cl(_collector, this, work_q, bm, ovflw); |
| 0 | 4325 while (true) { |
| 4326 cl.trim_queue(0); | |
| 4327 assert(work_q->size() == 0, "Should have been emptied above"); | |
| 4328 if (get_work_from_overflow_stack(ovflw, work_q)) { | |
| 4329 // Can't assert below because the work obtained from the | |
| 4330 // overflow stack may already have been stolen from us. | |
| 4331 // assert(work_q->size() > 0, "Work from overflow stack"); | |
| 4332 continue; | |
| 4333 } else if (task_queues()->steal(i, seed, /* reference */ obj_to_scan)) { | |
| 4334 assert(obj_to_scan->is_oop(), "Should be an oop"); | |
| 4335 assert(bm->isMarked((HeapWord*)obj_to_scan), "Grey object"); | |
| 4336 obj_to_scan->oop_iterate(&cl); | |
|
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|
4337 } else if (terminator()->offer_termination(&_term_term)) { |
| 0 | 4338 assert(work_q->size() == 0, "Impossible!"); |
| 4339 break; | |
|
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|
4340 } else if (yielding() || should_yield()) { |
|
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|
4341 yield(); |
| 0 | 4342 } |
| 4343 } | |
| 4344 } | |
| 4345 | |
| 4346 // This is run by the CMS (coordinator) thread. | |
| 4347 void CMSConcMarkingTask::coordinator_yield() { | |
| 4348 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 4349 "CMS thread should hold CMS token"); | |
| 4350 // First give up the locks, then yield, then re-lock | |
| 4351 // We should probably use a constructor/destructor idiom to | |
| 4352 // do this unlock/lock or modify the MutexUnlocker class to | |
| 4353 // serve our purpose. XXX | |
| 4354 assert_lock_strong(_bit_map_lock); | |
| 4355 _bit_map_lock->unlock(); | |
| 4356 ConcurrentMarkSweepThread::desynchronize(true); | |
| 4357 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 4358 _collector->stopTimer(); | |
| 4359 if (PrintCMSStatistics != 0) { | |
| 4360 _collector->incrementYields(); | |
| 4361 } | |
| 4362 _collector->icms_wait(); | |
| 4363 | |
| 4364 // It is possible for whichever thread initiated the yield request | |
| 4365 // not to get a chance to wake up and take the bitmap lock between | |
| 4366 // this thread releasing it and reacquiring it. So, while the | |
| 4367 // should_yield() flag is on, let's sleep for a bit to give the | |
| 4368 // other thread a chance to wake up. The limit imposed on the number | |
| 4369 // of iterations is defensive, to avoid any unforseen circumstances | |
| 4370 // putting us into an infinite loop. Since it's always been this | |
| 4371 // (coordinator_yield()) method that was observed to cause the | |
| 4372 // problem, we are using a parameter (CMSCoordinatorYieldSleepCount) | |
| 4373 // which is by default non-zero. For the other seven methods that | |
| 4374 // also perform the yield operation, as are using a different | |
| 4375 // parameter (CMSYieldSleepCount) which is by default zero. This way we | |
| 4376 // can enable the sleeping for those methods too, if necessary. | |
| 4377 // See 6442774. | |
| 4378 // | |
| 4379 // We really need to reconsider the synchronization between the GC | |
| 4380 // thread and the yield-requesting threads in the future and we | |
| 4381 // should really use wait/notify, which is the recommended | |
| 4382 // way of doing this type of interaction. Additionally, we should | |
| 4383 // consolidate the eight methods that do the yield operation and they | |
| 4384 // are almost identical into one for better maintenability and | |
| 4385 // readability. See 6445193. | |
| 4386 // | |
| 4387 // Tony 2006.06.29 | |
| 4388 for (unsigned i = 0; i < CMSCoordinatorYieldSleepCount && | |
|
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4389 ConcurrentMarkSweepThread::should_yield() && |
|
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4390 !CMSCollector::foregroundGCIsActive(); ++i) { |
| 0 | 4391 os::sleep(Thread::current(), 1, false); |
| 4392 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 4393 } | |
| 4394 | |
| 4395 ConcurrentMarkSweepThread::synchronize(true); | |
| 4396 _bit_map_lock->lock_without_safepoint_check(); | |
| 4397 _collector->startTimer(); | |
| 4398 } | |
| 4399 | |
| 4400 bool CMSCollector::do_marking_mt(bool asynch) { | |
| 1284 | 4401 assert(ConcGCThreads > 0 && conc_workers() != NULL, "precondition"); |
|
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4402 int num_workers = AdaptiveSizePolicy::calc_active_conc_workers( |
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4403 conc_workers()->total_workers(), |
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4404 conc_workers()->active_workers(), |
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4405 Threads::number_of_non_daemon_threads()); |
|
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|
4406 conc_workers()->set_active_workers(num_workers); |
| 0 | 4407 |
| 4408 CompactibleFreeListSpace* cms_space = _cmsGen->cmsSpace(); | |
| 4409 | |
|
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4410 CMSConcMarkingTask tsk(this, |
|
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4411 cms_space, |
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4412 asynch, |
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4413 conc_workers(), |
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|
4414 task_queues()); |
| 0 | 4415 |
| 4416 // Since the actual number of workers we get may be different | |
| 4417 // from the number we requested above, do we need to do anything different | |
| 4418 // below? In particular, may be we need to subclass the SequantialSubTasksDone | |
| 4419 // class?? XXX | |
| 4420 cms_space ->initialize_sequential_subtasks_for_marking(num_workers); | |
| 4421 | |
| 4422 // Refs discovery is already non-atomic. | |
| 4423 assert(!ref_processor()->discovery_is_atomic(), "Should be non-atomic"); | |
|
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|
4424 assert(ref_processor()->discovery_is_mt(), "Discovery should be MT"); |
| 0 | 4425 conc_workers()->start_task(&tsk); |
| 4426 while (tsk.yielded()) { | |
| 4427 tsk.coordinator_yield(); | |
| 4428 conc_workers()->continue_task(&tsk); | |
| 4429 } | |
| 4430 // If the task was aborted, _restart_addr will be non-NULL | |
| 4431 assert(tsk.completed() || _restart_addr != NULL, "Inconsistency"); | |
| 4432 while (_restart_addr != NULL) { | |
| 4433 // XXX For now we do not make use of ABORTED state and have not | |
| 4434 // yet implemented the right abort semantics (even in the original | |
| 4435 // single-threaded CMS case). That needs some more investigation | |
| 4436 // and is deferred for now; see CR# TBF. 07252005YSR. XXX | |
| 4437 assert(!CMSAbortSemantics || tsk.aborted(), "Inconsistency"); | |
| 4438 // If _restart_addr is non-NULL, a marking stack overflow | |
| 605 | 4439 // occurred; we need to do a fresh marking iteration from the |
| 0 | 4440 // indicated restart address. |
| 4441 if (_foregroundGCIsActive && asynch) { | |
| 4442 // We may be running into repeated stack overflows, having | |
| 4443 // reached the limit of the stack size, while making very | |
| 4444 // slow forward progress. It may be best to bail out and | |
| 4445 // let the foreground collector do its job. | |
| 4446 // Clear _restart_addr, so that foreground GC | |
| 4447 // works from scratch. This avoids the headache of | |
| 4448 // a "rescan" which would otherwise be needed because | |
| 4449 // of the dirty mod union table & card table. | |
| 4450 _restart_addr = NULL; | |
| 4451 return false; | |
| 4452 } | |
| 4453 // Adjust the task to restart from _restart_addr | |
| 4454 tsk.reset(_restart_addr); | |
| 4455 cms_space ->initialize_sequential_subtasks_for_marking(num_workers, | |
| 4456 _restart_addr); | |
| 4457 _restart_addr = NULL; | |
| 4458 // Get the workers going again | |
| 4459 conc_workers()->start_task(&tsk); | |
| 4460 while (tsk.yielded()) { | |
| 4461 tsk.coordinator_yield(); | |
| 4462 conc_workers()->continue_task(&tsk); | |
| 4463 } | |
| 4464 } | |
| 4465 assert(tsk.completed(), "Inconsistency"); | |
| 4466 assert(tsk.result() == true, "Inconsistency"); | |
| 4467 return true; | |
| 4468 } | |
| 4469 | |
| 4470 bool CMSCollector::do_marking_st(bool asynch) { | |
| 4471 ResourceMark rm; | |
| 4472 HandleMark hm; | |
| 4473 | |
|
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|
4474 // Temporarily make refs discovery single threaded (non-MT) |
|
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|
4475 ReferenceProcessorMTDiscoveryMutator rp_mut_discovery(ref_processor(), false); |
| 0 | 4476 MarkFromRootsClosure markFromRootsClosure(this, _span, &_markBitMap, |
|
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4477 &_markStack, CMSYield && asynch); |
| 0 | 4478 // the last argument to iterate indicates whether the iteration |
| 4479 // should be incremental with periodic yields. | |
| 4480 _markBitMap.iterate(&markFromRootsClosure); | |
| 4481 // If _restart_addr is non-NULL, a marking stack overflow | |
| 605 | 4482 // occurred; we need to do a fresh iteration from the |
| 0 | 4483 // indicated restart address. |
| 4484 while (_restart_addr != NULL) { | |
| 4485 if (_foregroundGCIsActive && asynch) { | |
| 4486 // We may be running into repeated stack overflows, having | |
| 4487 // reached the limit of the stack size, while making very | |
| 4488 // slow forward progress. It may be best to bail out and | |
| 4489 // let the foreground collector do its job. | |
| 4490 // Clear _restart_addr, so that foreground GC | |
| 4491 // works from scratch. This avoids the headache of | |
| 4492 // a "rescan" which would otherwise be needed because | |
| 4493 // of the dirty mod union table & card table. | |
| 4494 _restart_addr = NULL; | |
| 4495 return false; // indicating failure to complete marking | |
| 4496 } | |
| 4497 // Deal with stack overflow: | |
| 4498 // we restart marking from _restart_addr | |
| 4499 HeapWord* ra = _restart_addr; | |
| 4500 markFromRootsClosure.reset(ra); | |
| 4501 _restart_addr = NULL; | |
| 4502 _markBitMap.iterate(&markFromRootsClosure, ra, _span.end()); | |
| 4503 } | |
| 4504 return true; | |
| 4505 } | |
| 4506 | |
| 4507 void CMSCollector::preclean() { | |
| 4508 check_correct_thread_executing(); | |
| 4509 assert(Thread::current()->is_ConcurrentGC_thread(), "Wrong thread"); | |
| 4510 verify_work_stacks_empty(); | |
| 4511 verify_overflow_empty(); | |
| 4512 _abort_preclean = false; | |
| 4513 if (CMSPrecleaningEnabled) { | |
|
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4514 if (!CMSEdenChunksRecordAlways) { |
|
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4515 _eden_chunk_index = 0; |
|
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|
4516 } |
| 0 | 4517 size_t used = get_eden_used(); |
| 4518 size_t capacity = get_eden_capacity(); | |
| 4519 // Don't start sampling unless we will get sufficiently | |
| 4520 // many samples. | |
| 4521 if (used < (capacity/(CMSScheduleRemarkSamplingRatio * 100) | |
| 4522 * CMSScheduleRemarkEdenPenetration)) { | |
| 4523 _start_sampling = true; | |
| 4524 } else { | |
| 4525 _start_sampling = false; | |
| 4526 } | |
| 4527 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
| 4528 CMSPhaseAccounting pa(this, "preclean", !PrintGCDetails); | |
| 4529 preclean_work(CMSPrecleanRefLists1, CMSPrecleanSurvivors1); | |
| 4530 } | |
| 4531 CMSTokenSync x(true); // is cms thread | |
| 4532 if (CMSPrecleaningEnabled) { | |
| 4533 sample_eden(); | |
| 4534 _collectorState = AbortablePreclean; | |
| 4535 } else { | |
| 4536 _collectorState = FinalMarking; | |
| 4537 } | |
| 4538 verify_work_stacks_empty(); | |
| 4539 verify_overflow_empty(); | |
| 4540 } | |
| 4541 | |
| 4542 // Try and schedule the remark such that young gen | |
| 4543 // occupancy is CMSScheduleRemarkEdenPenetration %. | |
| 4544 void CMSCollector::abortable_preclean() { | |
| 4545 check_correct_thread_executing(); | |
| 4546 assert(CMSPrecleaningEnabled, "Inconsistent control state"); | |
| 4547 assert(_collectorState == AbortablePreclean, "Inconsistent control state"); | |
| 4548 | |
| 4549 // If Eden's current occupancy is below this threshold, | |
| 4550 // immediately schedule the remark; else preclean | |
| 4551 // past the next scavenge in an effort to | |
| 4552 // schedule the pause as described avove. By choosing | |
| 4553 // CMSScheduleRemarkEdenSizeThreshold >= max eden size | |
| 4554 // we will never do an actual abortable preclean cycle. | |
| 4555 if (get_eden_used() > CMSScheduleRemarkEdenSizeThreshold) { | |
| 4556 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
| 4557 CMSPhaseAccounting pa(this, "abortable-preclean", !PrintGCDetails); | |
| 4558 // We need more smarts in the abortable preclean | |
| 4559 // loop below to deal with cases where allocation | |
| 4560 // in young gen is very very slow, and our precleaning | |
| 4561 // is running a losing race against a horde of | |
| 4562 // mutators intent on flooding us with CMS updates | |
| 4563 // (dirty cards). | |
| 4564 // One, admittedly dumb, strategy is to give up | |
| 4565 // after a certain number of abortable precleaning loops | |
| 4566 // or after a certain maximum time. We want to make | |
| 4567 // this smarter in the next iteration. | |
| 4568 // XXX FIX ME!!! YSR | |
| 4569 size_t loops = 0, workdone = 0, cumworkdone = 0, waited = 0; | |
| 4570 while (!(should_abort_preclean() || | |
| 4571 ConcurrentMarkSweepThread::should_terminate())) { | |
| 4572 workdone = preclean_work(CMSPrecleanRefLists2, CMSPrecleanSurvivors2); | |
| 4573 cumworkdone += workdone; | |
| 4574 loops++; | |
| 4575 // Voluntarily terminate abortable preclean phase if we have | |
| 4576 // been at it for too long. | |
| 4577 if ((CMSMaxAbortablePrecleanLoops != 0) && | |
| 4578 loops >= CMSMaxAbortablePrecleanLoops) { | |
| 4579 if (PrintGCDetails) { | |
| 4580 gclog_or_tty->print(" CMS: abort preclean due to loops "); | |
| 4581 } | |
| 4582 break; | |
| 4583 } | |
| 4584 if (pa.wallclock_millis() > CMSMaxAbortablePrecleanTime) { | |
| 4585 if (PrintGCDetails) { | |
| 4586 gclog_or_tty->print(" CMS: abort preclean due to time "); | |
| 4587 } | |
| 4588 break; | |
| 4589 } | |
| 4590 // If we are doing little work each iteration, we should | |
| 4591 // take a short break. | |
| 4592 if (workdone < CMSAbortablePrecleanMinWorkPerIteration) { | |
| 4593 // Sleep for some time, waiting for work to accumulate | |
| 4594 stopTimer(); | |
| 4595 cmsThread()->wait_on_cms_lock(CMSAbortablePrecleanWaitMillis); | |
| 4596 startTimer(); | |
| 4597 waited++; | |
| 4598 } | |
| 4599 } | |
| 4600 if (PrintCMSStatistics > 0) { | |
| 4601 gclog_or_tty->print(" [%d iterations, %d waits, %d cards)] ", | |
| 4602 loops, waited, cumworkdone); | |
| 4603 } | |
| 4604 } | |
| 4605 CMSTokenSync x(true); // is cms thread | |
| 4606 if (_collectorState != Idling) { | |
| 4607 assert(_collectorState == AbortablePreclean, | |
| 4608 "Spontaneous state transition?"); | |
| 4609 _collectorState = FinalMarking; | |
| 4610 } // Else, a foreground collection completed this CMS cycle. | |
| 4611 return; | |
| 4612 } | |
| 4613 | |
| 4614 // Respond to an Eden sampling opportunity | |
| 4615 void CMSCollector::sample_eden() { | |
| 4616 // Make sure a young gc cannot sneak in between our | |
| 4617 // reading and recording of a sample. | |
| 4618 assert(Thread::current()->is_ConcurrentGC_thread(), | |
| 4619 "Only the cms thread may collect Eden samples"); | |
| 4620 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 4621 "Should collect samples while holding CMS token"); | |
| 4622 if (!_start_sampling) { | |
| 4623 return; | |
| 4624 } | |
|
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4625 // When CMSEdenChunksRecordAlways is true, the eden chunk array |
|
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4626 // is populated by the young generation. |
|
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|
4627 if (_eden_chunk_array != NULL && !CMSEdenChunksRecordAlways) { |
| 0 | 4628 if (_eden_chunk_index < _eden_chunk_capacity) { |
| 4629 _eden_chunk_array[_eden_chunk_index] = *_top_addr; // take sample | |
| 4630 assert(_eden_chunk_array[_eden_chunk_index] <= *_end_addr, | |
| 4631 "Unexpected state of Eden"); | |
| 4632 // We'd like to check that what we just sampled is an oop-start address; | |
| 4633 // however, we cannot do that here since the object may not yet have been | |
| 4634 // initialized. So we'll instead do the check when we _use_ this sample | |
| 4635 // later. | |
| 4636 if (_eden_chunk_index == 0 || | |
| 4637 (pointer_delta(_eden_chunk_array[_eden_chunk_index], | |
| 4638 _eden_chunk_array[_eden_chunk_index-1]) | |
| 4639 >= CMSSamplingGrain)) { | |
| 4640 _eden_chunk_index++; // commit sample | |
| 4641 } | |
| 4642 } | |
| 4643 } | |
| 4644 if ((_collectorState == AbortablePreclean) && !_abort_preclean) { | |
| 4645 size_t used = get_eden_used(); | |
| 4646 size_t capacity = get_eden_capacity(); | |
| 4647 assert(used <= capacity, "Unexpected state of Eden"); | |
| 4648 if (used > (capacity/100 * CMSScheduleRemarkEdenPenetration)) { | |
| 4649 _abort_preclean = true; | |
| 4650 } | |
| 4651 } | |
| 4652 } | |
| 4653 | |
| 4654 | |
| 4655 size_t CMSCollector::preclean_work(bool clean_refs, bool clean_survivor) { | |
| 4656 assert(_collectorState == Precleaning || | |
| 4657 _collectorState == AbortablePreclean, "incorrect state"); | |
| 4658 ResourceMark rm; | |
| 4659 HandleMark hm; | |
|
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4660 |
|
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|
4661 // Precleaning is currently not MT but the reference processor |
|
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4662 // may be set for MT. Disable it temporarily here. |
|
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4663 ReferenceProcessor* rp = ref_processor(); |
|
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|
4664 ReferenceProcessorMTDiscoveryMutator rp_mut_discovery(rp, false); |
|
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|
4665 |
| 0 | 4666 // Do one pass of scrubbing the discovered reference lists |
| 4667 // to remove any reference objects with strongly-reachable | |
| 4668 // referents. | |
| 4669 if (clean_refs) { | |
| 4670 CMSPrecleanRefsYieldClosure yield_cl(this); | |
| 4671 assert(rp->span().equals(_span), "Spans should be equal"); | |
| 4672 CMSKeepAliveClosure keep_alive(this, _span, &_markBitMap, | |
|
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4673 &_markStack, true /* preclean */); |
| 0 | 4674 CMSDrainMarkingStackClosure complete_trace(this, |
|
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4675 _span, &_markBitMap, &_markStack, |
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|
4676 &keep_alive, true /* preclean */); |
| 0 | 4677 |
| 4678 // We don't want this step to interfere with a young | |
| 4679 // collection because we don't want to take CPU | |
| 4680 // or memory bandwidth away from the young GC threads | |
| 4681 // (which may be as many as there are CPUs). | |
| 4682 // Note that we don't need to protect ourselves from | |
| 4683 // interference with mutators because they can't | |
| 4684 // manipulate the discovered reference lists nor affect | |
| 4685 // the computed reachability of the referents, the | |
| 4686 // only properties manipulated by the precleaning | |
| 4687 // of these reference lists. | |
| 4688 stopTimer(); | |
| 4689 CMSTokenSyncWithLocks x(true /* is cms thread */, | |
| 4690 bitMapLock()); | |
| 4691 startTimer(); | |
| 4692 sample_eden(); | |
| 935 | 4693 |
| 0 | 4694 // The following will yield to allow foreground |
| 4695 // collection to proceed promptly. XXX YSR: | |
| 4696 // The code in this method may need further | |
| 4697 // tweaking for better performance and some restructuring | |
| 4698 // for cleaner interfaces. | |
| 10405 | 4699 GCTimer *gc_timer = NULL; // Currently not tracing concurrent phases |
| 0 | 4700 rp->preclean_discovered_references( |
| 10405 | 4701 rp->is_alive_non_header(), &keep_alive, &complete_trace, &yield_cl, |
| 4702 gc_timer); | |
| 0 | 4703 } |
| 4704 | |
| 4705 if (clean_survivor) { // preclean the active survivor space(s) | |
| 4706 assert(_young_gen->kind() == Generation::DefNew || | |
| 4707 _young_gen->kind() == Generation::ParNew || | |
| 4708 _young_gen->kind() == Generation::ASParNew, | |
| 4709 "incorrect type for cast"); | |
| 4710 DefNewGeneration* dng = (DefNewGeneration*)_young_gen; | |
| 4711 PushAndMarkClosure pam_cl(this, _span, ref_processor(), | |
| 4712 &_markBitMap, &_modUnionTable, | |
|
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4713 &_markStack, true /* precleaning phase */); |
| 0 | 4714 stopTimer(); |
| 4715 CMSTokenSyncWithLocks ts(true /* is cms thread */, | |
| 4716 bitMapLock()); | |
| 4717 startTimer(); | |
| 4718 unsigned int before_count = | |
| 4719 GenCollectedHeap::heap()->total_collections(); | |
| 4720 SurvivorSpacePrecleanClosure | |
| 4721 sss_cl(this, _span, &_markBitMap, &_markStack, | |
| 4722 &pam_cl, before_count, CMSYield); | |
| 4723 dng->from()->object_iterate_careful(&sss_cl); | |
| 4724 dng->to()->object_iterate_careful(&sss_cl); | |
| 4725 } | |
| 4726 MarkRefsIntoAndScanClosure | |
| 4727 mrias_cl(_span, ref_processor(), &_markBitMap, &_modUnionTable, | |
|
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|
4728 &_markStack, this, CMSYield, |
| 0 | 4729 true /* precleaning phase */); |
| 4730 // CAUTION: The following closure has persistent state that may need to | |
| 4731 // be reset upon a decrease in the sequence of addresses it | |
| 4732 // processes. | |
| 4733 ScanMarkedObjectsAgainCarefullyClosure | |
| 4734 smoac_cl(this, _span, | |
|
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|
4735 &_markBitMap, &_markStack, &mrias_cl, CMSYield); |
| 0 | 4736 |
| 4737 // Preclean dirty cards in ModUnionTable and CardTable using | |
| 4738 // appropriate convergence criterion; | |
| 4739 // repeat CMSPrecleanIter times unless we find that | |
| 4740 // we are losing. | |
| 4741 assert(CMSPrecleanIter < 10, "CMSPrecleanIter is too large"); | |
| 4742 assert(CMSPrecleanNumerator < CMSPrecleanDenominator, | |
| 4743 "Bad convergence multiplier"); | |
| 4744 assert(CMSPrecleanThreshold >= 100, | |
| 4745 "Unreasonably low CMSPrecleanThreshold"); | |
| 4746 | |
| 4747 size_t numIter, cumNumCards, lastNumCards, curNumCards; | |
| 4748 for (numIter = 0, cumNumCards = lastNumCards = curNumCards = 0; | |
| 4749 numIter < CMSPrecleanIter; | |
| 4750 numIter++, lastNumCards = curNumCards, cumNumCards += curNumCards) { | |
| 4751 curNumCards = preclean_mod_union_table(_cmsGen, &smoac_cl); | |
| 4752 if (Verbose && PrintGCDetails) { | |
| 4753 gclog_or_tty->print(" (modUnionTable: %d cards)", curNumCards); | |
| 4754 } | |
| 4755 // Either there are very few dirty cards, so re-mark | |
| 4756 // pause will be small anyway, or our pre-cleaning isn't | |
| 4757 // that much faster than the rate at which cards are being | |
| 4758 // dirtied, so we might as well stop and re-mark since | |
| 4759 // precleaning won't improve our re-mark time by much. | |
| 4760 if (curNumCards <= CMSPrecleanThreshold || | |
| 4761 (numIter > 0 && | |
| 4762 (curNumCards * CMSPrecleanDenominator > | |
| 4763 lastNumCards * CMSPrecleanNumerator))) { | |
| 4764 numIter++; | |
| 4765 cumNumCards += curNumCards; | |
| 4766 break; | |
| 4767 } | |
| 4768 } | |
|
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4769 |
|
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4770 preclean_klasses(&mrias_cl, _cmsGen->freelistLock()); |
|
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|
4771 |
| 0 | 4772 curNumCards = preclean_card_table(_cmsGen, &smoac_cl); |
| 4773 cumNumCards += curNumCards; | |
| 4774 if (PrintGCDetails && PrintCMSStatistics != 0) { | |
| 4775 gclog_or_tty->print_cr(" (cardTable: %d cards, re-scanned %d cards, %d iterations)", | |
| 4776 curNumCards, cumNumCards, numIter); | |
| 4777 } | |
| 4778 return cumNumCards; // as a measure of useful work done | |
| 4779 } | |
| 4780 | |
| 4781 // PRECLEANING NOTES: | |
| 4782 // Precleaning involves: | |
| 4783 // . reading the bits of the modUnionTable and clearing the set bits. | |
| 4784 // . For the cards corresponding to the set bits, we scan the | |
| 4785 // objects on those cards. This means we need the free_list_lock | |
| 4786 // so that we can safely iterate over the CMS space when scanning | |
| 4787 // for oops. | |
| 4788 // . When we scan the objects, we'll be both reading and setting | |
| 4789 // marks in the marking bit map, so we'll need the marking bit map. | |
| 4790 // . For protecting _collector_state transitions, we take the CGC_lock. | |
| 4791 // Note that any races in the reading of of card table entries by the | |
| 4792 // CMS thread on the one hand and the clearing of those entries by the | |
| 4793 // VM thread or the setting of those entries by the mutator threads on the | |
| 4794 // other are quite benign. However, for efficiency it makes sense to keep | |
| 4795 // the VM thread from racing with the CMS thread while the latter is | |
| 4796 // dirty card info to the modUnionTable. We therefore also use the | |
| 4797 // CGC_lock to protect the reading of the card table and the mod union | |
| 4798 // table by the CM thread. | |
| 4799 // . We run concurrently with mutator updates, so scanning | |
| 4800 // needs to be done carefully -- we should not try to scan | |
| 4801 // potentially uninitialized objects. | |
| 4802 // | |
| 4803 // Locking strategy: While holding the CGC_lock, we scan over and | |
| 4804 // reset a maximal dirty range of the mod union / card tables, then lock | |
| 4805 // the free_list_lock and bitmap lock to do a full marking, then | |
| 4806 // release these locks; and repeat the cycle. This allows for a | |
| 4807 // certain amount of fairness in the sharing of these locks between | |
| 4808 // the CMS collector on the one hand, and the VM thread and the | |
| 4809 // mutators on the other. | |
| 4810 | |
| 4811 // NOTE: preclean_mod_union_table() and preclean_card_table() | |
| 4812 // further below are largely identical; if you need to modify | |
| 4813 // one of these methods, please check the other method too. | |
| 4814 | |
| 4815 size_t CMSCollector::preclean_mod_union_table( | |
| 4816 ConcurrentMarkSweepGeneration* gen, | |
| 4817 ScanMarkedObjectsAgainCarefullyClosure* cl) { | |
| 4818 verify_work_stacks_empty(); | |
| 4819 verify_overflow_empty(); | |
| 4820 | |
| 4821 // strategy: starting with the first card, accumulate contiguous | |
| 4822 // ranges of dirty cards; clear these cards, then scan the region | |
| 4823 // covered by these cards. | |
| 4824 | |
| 4825 // Since all of the MUT is committed ahead, we can just use | |
| 4826 // that, in case the generations expand while we are precleaning. | |
| 4827 // It might also be fine to just use the committed part of the | |
| 4828 // generation, but we might potentially miss cards when the | |
| 4829 // generation is rapidly expanding while we are in the midst | |
| 4830 // of precleaning. | |
| 4831 HeapWord* startAddr = gen->reserved().start(); | |
| 4832 HeapWord* endAddr = gen->reserved().end(); | |
| 4833 | |
| 4834 cl->setFreelistLock(gen->freelistLock()); // needed for yielding | |
| 4835 | |
| 4836 size_t numDirtyCards, cumNumDirtyCards; | |
| 4837 HeapWord *nextAddr, *lastAddr; | |
| 4838 for (cumNumDirtyCards = numDirtyCards = 0, | |
| 4839 nextAddr = lastAddr = startAddr; | |
| 4840 nextAddr < endAddr; | |
| 4841 nextAddr = lastAddr, cumNumDirtyCards += numDirtyCards) { | |
| 4842 | |
| 4843 ResourceMark rm; | |
| 4844 HandleMark hm; | |
| 4845 | |
| 4846 MemRegion dirtyRegion; | |
| 4847 { | |
| 4848 stopTimer(); | |
| 935 | 4849 // Potential yield point |
| 0 | 4850 CMSTokenSync ts(true); |
| 4851 startTimer(); | |
| 4852 sample_eden(); | |
| 4853 // Get dirty region starting at nextOffset (inclusive), | |
| 4854 // simultaneously clearing it. | |
| 4855 dirtyRegion = | |
| 4856 _modUnionTable.getAndClearMarkedRegion(nextAddr, endAddr); | |
| 4857 assert(dirtyRegion.start() >= nextAddr, | |
| 4858 "returned region inconsistent?"); | |
| 4859 } | |
| 4860 // Remember where the next search should begin. | |
| 4861 // The returned region (if non-empty) is a right open interval, | |
| 4862 // so lastOffset is obtained from the right end of that | |
| 4863 // interval. | |
| 4864 lastAddr = dirtyRegion.end(); | |
| 4865 // Should do something more transparent and less hacky XXX | |
| 4866 numDirtyCards = | |
| 4867 _modUnionTable.heapWordDiffToOffsetDiff(dirtyRegion.word_size()); | |
| 4868 | |
| 4869 // We'll scan the cards in the dirty region (with periodic | |
| 4870 // yields for foreground GC as needed). | |
| 4871 if (!dirtyRegion.is_empty()) { | |
| 4872 assert(numDirtyCards > 0, "consistency check"); | |
| 4873 HeapWord* stop_point = NULL; | |
|
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|
4874 stopTimer(); |
| 935 | 4875 // Potential yield point |
|
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|
4876 CMSTokenSyncWithLocks ts(true, gen->freelistLock(), |
|
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|
4877 bitMapLock()); |
|
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|
4878 startTimer(); |
| 0 | 4879 { |
| 4880 verify_work_stacks_empty(); | |
| 4881 verify_overflow_empty(); | |
| 4882 sample_eden(); | |
| 4883 stop_point = | |
| 4884 gen->cmsSpace()->object_iterate_careful_m(dirtyRegion, cl); | |
| 4885 } | |
| 4886 if (stop_point != NULL) { | |
| 4887 // The careful iteration stopped early either because it found an | |
| 4888 // uninitialized object, or because we were in the midst of an | |
| 4889 // "abortable preclean", which should now be aborted. Redirty | |
| 4890 // the bits corresponding to the partially-scanned or unscanned | |
| 4891 // cards. We'll either restart at the next block boundary or | |
| 4892 // abort the preclean. | |
|
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4893 assert((_collectorState == AbortablePreclean && should_abort_preclean()), |
|
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4894 "Should only be AbortablePreclean."); |
| 0 | 4895 _modUnionTable.mark_range(MemRegion(stop_point, dirtyRegion.end())); |
| 4896 if (should_abort_preclean()) { | |
| 4897 break; // out of preclean loop | |
| 4898 } else { | |
| 4899 // Compute the next address at which preclean should pick up; | |
| 4900 // might need bitMapLock in order to read P-bits. | |
| 4901 lastAddr = next_card_start_after_block(stop_point); | |
| 4902 } | |
| 4903 } | |
| 4904 } else { | |
| 4905 assert(lastAddr == endAddr, "consistency check"); | |
| 4906 assert(numDirtyCards == 0, "consistency check"); | |
| 4907 break; | |
| 4908 } | |
| 4909 } | |
| 4910 verify_work_stacks_empty(); | |
| 4911 verify_overflow_empty(); | |
| 4912 return cumNumDirtyCards; | |
| 4913 } | |
| 4914 | |
| 4915 // NOTE: preclean_mod_union_table() above and preclean_card_table() | |
| 4916 // below are largely identical; if you need to modify | |
| 4917 // one of these methods, please check the other method too. | |
| 4918 | |
| 4919 size_t CMSCollector::preclean_card_table(ConcurrentMarkSweepGeneration* gen, | |
| 4920 ScanMarkedObjectsAgainCarefullyClosure* cl) { | |
| 4921 // strategy: it's similar to precleamModUnionTable above, in that | |
| 4922 // we accumulate contiguous ranges of dirty cards, mark these cards | |
| 4923 // precleaned, then scan the region covered by these cards. | |
| 4924 HeapWord* endAddr = (HeapWord*)(gen->_virtual_space.high()); | |
| 4925 HeapWord* startAddr = (HeapWord*)(gen->_virtual_space.low()); | |
| 4926 | |
| 4927 cl->setFreelistLock(gen->freelistLock()); // needed for yielding | |
| 4928 | |
| 4929 size_t numDirtyCards, cumNumDirtyCards; | |
| 4930 HeapWord *lastAddr, *nextAddr; | |
| 4931 | |
| 4932 for (cumNumDirtyCards = numDirtyCards = 0, | |
| 4933 nextAddr = lastAddr = startAddr; | |
| 4934 nextAddr < endAddr; | |
| 4935 nextAddr = lastAddr, cumNumDirtyCards += numDirtyCards) { | |
| 4936 | |
| 4937 ResourceMark rm; | |
| 4938 HandleMark hm; | |
| 4939 | |
| 4940 MemRegion dirtyRegion; | |
| 4941 { | |
| 4942 // See comments in "Precleaning notes" above on why we | |
| 4943 // do this locking. XXX Could the locking overheads be | |
| 4944 // too high when dirty cards are sparse? [I don't think so.] | |
| 4945 stopTimer(); | |
| 4946 CMSTokenSync x(true); // is cms thread | |
| 4947 startTimer(); | |
| 4948 sample_eden(); | |
| 4949 // Get and clear dirty region from card table | |
|
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4950 dirtyRegion = _ct->ct_bs()->dirty_card_range_after_reset( |
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4951 MemRegion(nextAddr, endAddr), |
|
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4952 true, |
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4953 CardTableModRefBS::precleaned_card_val()); |
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4954 |
| 0 | 4955 assert(dirtyRegion.start() >= nextAddr, |
| 4956 "returned region inconsistent?"); | |
| 4957 } | |
| 4958 lastAddr = dirtyRegion.end(); | |
| 4959 numDirtyCards = | |
| 4960 dirtyRegion.word_size()/CardTableModRefBS::card_size_in_words; | |
| 4961 | |
| 4962 if (!dirtyRegion.is_empty()) { | |
| 4963 stopTimer(); | |
| 4964 CMSTokenSyncWithLocks ts(true, gen->freelistLock(), bitMapLock()); | |
| 4965 startTimer(); | |
| 4966 sample_eden(); | |
| 4967 verify_work_stacks_empty(); | |
| 4968 verify_overflow_empty(); | |
| 4969 HeapWord* stop_point = | |
| 4970 gen->cmsSpace()->object_iterate_careful_m(dirtyRegion, cl); | |
| 4971 if (stop_point != NULL) { | |
|
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4972 assert((_collectorState == AbortablePreclean && should_abort_preclean()), |
|
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4973 "Should only be AbortablePreclean."); |
| 0 | 4974 _ct->ct_bs()->invalidate(MemRegion(stop_point, dirtyRegion.end())); |
| 4975 if (should_abort_preclean()) { | |
| 4976 break; // out of preclean loop | |
| 4977 } else { | |
| 4978 // Compute the next address at which preclean should pick up. | |
| 4979 lastAddr = next_card_start_after_block(stop_point); | |
| 4980 } | |
| 4981 } | |
| 4982 } else { | |
| 4983 break; | |
| 4984 } | |
| 4985 } | |
| 4986 verify_work_stacks_empty(); | |
| 4987 verify_overflow_empty(); | |
| 4988 return cumNumDirtyCards; | |
| 4989 } | |
| 4990 | |
|
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4991 class PrecleanKlassClosure : public KlassClosure { |
|
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4992 CMKlassClosure _cm_klass_closure; |
|
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4993 public: |
|
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|
4994 PrecleanKlassClosure(OopClosure* oop_closure) : _cm_klass_closure(oop_closure) {} |
|
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4995 void do_klass(Klass* k) { |
|
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4996 if (k->has_accumulated_modified_oops()) { |
|
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4997 k->clear_accumulated_modified_oops(); |
|
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4998 |
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4999 _cm_klass_closure.do_klass(k); |
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5000 } |
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5001 } |
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5002 }; |
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5003 |
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5004 // The freelist lock is needed to prevent asserts, is it really needed? |
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5005 void CMSCollector::preclean_klasses(MarkRefsIntoAndScanClosure* cl, Mutex* freelistLock) { |
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5006 |
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5007 cl->set_freelistLock(freelistLock); |
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5008 |
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5009 CMSTokenSyncWithLocks ts(true, freelistLock, bitMapLock()); |
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5010 |
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5011 // SSS: Add equivalent to ScanMarkedObjectsAgainCarefullyClosure::do_yield_check and should_abort_preclean? |
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5012 // SSS: We should probably check if precleaning should be aborted, at suitable intervals? |
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5013 PrecleanKlassClosure preclean_klass_closure(cl); |
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5014 ClassLoaderDataGraph::classes_do(&preclean_klass_closure); |
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5015 |
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5016 verify_work_stacks_empty(); |
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5017 verify_overflow_empty(); |
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5018 } |
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5019 |
| 0 | 5020 void CMSCollector::checkpointRootsFinal(bool asynch, |
| 5021 bool clear_all_soft_refs, bool init_mark_was_synchronous) { | |
| 5022 assert(_collectorState == FinalMarking, "incorrect state transition?"); | |
| 5023 check_correct_thread_executing(); | |
| 5024 // world is stopped at this checkpoint | |
| 5025 assert(SafepointSynchronize::is_at_safepoint(), | |
| 5026 "world should be stopped"); | |
|
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5027 TraceCMSMemoryManagerStats tms(_collectorState,GenCollectedHeap::heap()->gc_cause()); |
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5028 |
| 0 | 5029 verify_work_stacks_empty(); |
| 5030 verify_overflow_empty(); | |
| 5031 | |
| 5032 SpecializationStats::clear(); | |
| 5033 if (PrintGCDetails) { | |
| 5034 gclog_or_tty->print("[YG occupancy: "SIZE_FORMAT" K ("SIZE_FORMAT" K)]", | |
| 5035 _young_gen->used() / K, | |
| 5036 _young_gen->capacity() / K); | |
| 5037 } | |
| 5038 if (asynch) { | |
| 5039 if (CMSScavengeBeforeRemark) { | |
| 5040 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 5041 // Temporarily set flag to false, GCH->do_collection will | |
| 5042 // expect it to be false and set to true | |
| 5043 FlagSetting fl(gch->_is_gc_active, false); | |
| 10405 | 5044 NOT_PRODUCT(GCTraceTime t("Scavenge-Before-Remark", |
| 5045 PrintGCDetails && Verbose, true, _gc_timer_cm);) | |
| 0 | 5046 int level = _cmsGen->level() - 1; |
| 5047 if (level >= 0) { | |
| 5048 gch->do_collection(true, // full (i.e. force, see below) | |
| 5049 false, // !clear_all_soft_refs | |
| 5050 0, // size | |
| 5051 false, // is_tlab | |
| 5052 level // max_level | |
| 5053 ); | |
| 5054 } | |
| 5055 } | |
| 5056 FreelistLocker x(this); | |
| 5057 MutexLockerEx y(bitMapLock(), | |
| 5058 Mutex::_no_safepoint_check_flag); | |
| 5059 assert(!init_mark_was_synchronous, "but that's impossible!"); | |
| 5060 checkpointRootsFinalWork(asynch, clear_all_soft_refs, false); | |
| 5061 } else { | |
| 5062 // already have all the locks | |
| 5063 checkpointRootsFinalWork(asynch, clear_all_soft_refs, | |
| 5064 init_mark_was_synchronous); | |
| 5065 } | |
| 5066 verify_work_stacks_empty(); | |
| 5067 verify_overflow_empty(); | |
| 5068 SpecializationStats::print(); | |
| 5069 } | |
| 5070 | |
| 5071 void CMSCollector::checkpointRootsFinalWork(bool asynch, | |
| 5072 bool clear_all_soft_refs, bool init_mark_was_synchronous) { | |
| 5073 | |
| 10405 | 5074 NOT_PRODUCT(GCTraceTime tr("checkpointRootsFinalWork", PrintGCDetails, false, _gc_timer_cm);) |
| 0 | 5075 |
| 5076 assert(haveFreelistLocks(), "must have free list locks"); | |
| 5077 assert_lock_strong(bitMapLock()); | |
| 5078 | |
| 5079 if (UseAdaptiveSizePolicy) { | |
| 5080 size_policy()->checkpoint_roots_final_begin(); | |
| 5081 } | |
| 5082 | |
| 5083 ResourceMark rm; | |
| 5084 HandleMark hm; | |
| 5085 | |
| 5086 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 5087 | |
|
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|
5088 if (should_unload_classes()) { |
| 0 | 5089 CodeCache::gc_prologue(); |
| 5090 } | |
| 5091 assert(haveFreelistLocks(), "must have free list locks"); | |
| 5092 assert_lock_strong(bitMapLock()); | |
| 5093 | |
| 5094 if (!init_mark_was_synchronous) { | |
| 5095 // We might assume that we need not fill TLAB's when | |
| 5096 // CMSScavengeBeforeRemark is set, because we may have just done | |
| 5097 // a scavenge which would have filled all TLAB's -- and besides | |
| 5098 // Eden would be empty. This however may not always be the case -- | |
| 5099 // for instance although we asked for a scavenge, it may not have | |
| 5100 // happened because of a JNI critical section. We probably need | |
| 5101 // a policy for deciding whether we can in that case wait until | |
| 5102 // the critical section releases and then do the remark following | |
| 5103 // the scavenge, and skip it here. In the absence of that policy, | |
| 5104 // or of an indication of whether the scavenge did indeed occur, | |
| 5105 // we cannot rely on TLAB's having been filled and must do | |
| 5106 // so here just in case a scavenge did not happen. | |
| 5107 gch->ensure_parsability(false); // fill TLAB's, but no need to retire them | |
| 5108 // Update the saved marks which may affect the root scans. | |
| 5109 gch->save_marks(); | |
| 5110 | |
|
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5111 if (CMSPrintEdenSurvivorChunks) { |
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5112 print_eden_and_survivor_chunk_arrays(); |
|
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5113 } |
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|
5114 |
| 0 | 5115 { |
| 5116 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact;) | |
| 5117 | |
| 5118 // Note on the role of the mod union table: | |
| 5119 // Since the marker in "markFromRoots" marks concurrently with | |
| 5120 // mutators, it is possible for some reachable objects not to have been | |
| 5121 // scanned. For instance, an only reference to an object A was | |
| 5122 // placed in object B after the marker scanned B. Unless B is rescanned, | |
| 5123 // A would be collected. Such updates to references in marked objects | |
| 5124 // are detected via the mod union table which is the set of all cards | |
| 5125 // dirtied since the first checkpoint in this GC cycle and prior to | |
| 5126 // the most recent young generation GC, minus those cleaned up by the | |
| 5127 // concurrent precleaning. | |
|
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5128 if (CMSParallelRemarkEnabled && CollectedHeap::use_parallel_gc_threads()) { |
| 10405 | 5129 GCTraceTime t("Rescan (parallel) ", PrintGCDetails, false, _gc_timer_cm); |
| 0 | 5130 do_remark_parallel(); |
| 5131 } else { | |
| 10405 | 5132 GCTraceTime t("Rescan (non-parallel) ", PrintGCDetails, false, |
| 5133 _gc_timer_cm); | |
| 0 | 5134 do_remark_non_parallel(); |
| 5135 } | |
| 5136 } | |
| 5137 } else { | |
| 5138 assert(!asynch, "Can't have init_mark_was_synchronous in asynch mode"); | |
| 5139 // The initial mark was stop-world, so there's no rescanning to | |
| 5140 // do; go straight on to the next step below. | |
| 5141 } | |
| 5142 verify_work_stacks_empty(); | |
| 5143 verify_overflow_empty(); | |
| 5144 | |
| 5145 { | |
| 10405 | 5146 NOT_PRODUCT(GCTraceTime ts("refProcessingWork", PrintGCDetails, false, _gc_timer_cm);) |
| 0 | 5147 refProcessingWork(asynch, clear_all_soft_refs); |
| 5148 } | |
| 5149 verify_work_stacks_empty(); | |
| 5150 verify_overflow_empty(); | |
| 5151 | |
|
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|
5152 if (should_unload_classes()) { |
| 0 | 5153 CodeCache::gc_epilogue(); |
| 5154 } | |
|
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|
5155 JvmtiExport::gc_epilogue(); |
| 0 | 5156 |
| 5157 // If we encountered any (marking stack / work queue) overflow | |
| 5158 // events during the current CMS cycle, take appropriate | |
| 5159 // remedial measures, where possible, so as to try and avoid | |
| 5160 // recurrence of that condition. | |
| 5161 assert(_markStack.isEmpty(), "No grey objects"); | |
| 5162 size_t ser_ovflw = _ser_pmc_remark_ovflw + _ser_pmc_preclean_ovflw + | |
|
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|
5163 _ser_kac_ovflw + _ser_kac_preclean_ovflw; |
| 0 | 5164 if (ser_ovflw > 0) { |
| 5165 if (PrintCMSStatistics != 0) { | |
| 5166 gclog_or_tty->print_cr("Marking stack overflow (benign) " | |
|
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|
5167 "(pmc_pc="SIZE_FORMAT", pmc_rm="SIZE_FORMAT", kac="SIZE_FORMAT |
|
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|
5168 ", kac_preclean="SIZE_FORMAT")", |
| 0 | 5169 _ser_pmc_preclean_ovflw, _ser_pmc_remark_ovflw, |
|
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|
5170 _ser_kac_ovflw, _ser_kac_preclean_ovflw); |
| 0 | 5171 } |
| 5172 _markStack.expand(); | |
| 5173 _ser_pmc_remark_ovflw = 0; | |
| 5174 _ser_pmc_preclean_ovflw = 0; | |
|
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|
5175 _ser_kac_preclean_ovflw = 0; |
| 0 | 5176 _ser_kac_ovflw = 0; |
| 5177 } | |
| 5178 if (_par_pmc_remark_ovflw > 0 || _par_kac_ovflw > 0) { | |
| 5179 if (PrintCMSStatistics != 0) { | |
| 5180 gclog_or_tty->print_cr("Work queue overflow (benign) " | |
| 5181 "(pmc_rm="SIZE_FORMAT", kac="SIZE_FORMAT")", | |
| 5182 _par_pmc_remark_ovflw, _par_kac_ovflw); | |
| 5183 } | |
| 5184 _par_pmc_remark_ovflw = 0; | |
| 5185 _par_kac_ovflw = 0; | |
| 5186 } | |
| 5187 if (PrintCMSStatistics != 0) { | |
| 5188 if (_markStack._hit_limit > 0) { | |
| 5189 gclog_or_tty->print_cr(" (benign) Hit max stack size limit ("SIZE_FORMAT")", | |
| 5190 _markStack._hit_limit); | |
| 5191 } | |
| 5192 if (_markStack._failed_double > 0) { | |
| 5193 gclog_or_tty->print_cr(" (benign) Failed stack doubling ("SIZE_FORMAT")," | |
| 5194 " current capacity "SIZE_FORMAT, | |
| 5195 _markStack._failed_double, | |
| 5196 _markStack.capacity()); | |
| 5197 } | |
| 5198 } | |
| 5199 _markStack._hit_limit = 0; | |
| 5200 _markStack._failed_double = 0; | |
| 5201 | |
| 5202 if ((VerifyAfterGC || VerifyDuringGC) && | |
| 5203 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
| 5204 verify_after_remark(); | |
| 5205 } | |
| 5206 | |
| 10405 | 5207 _gc_tracer_cm->report_object_count_after_gc(&_is_alive_closure); |
| 5208 | |
| 0 | 5209 // Change under the freelistLocks. |
| 5210 _collectorState = Sweeping; | |
| 5211 // Call isAllClear() under bitMapLock | |
|
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5212 assert(_modUnionTable.isAllClear(), |
|
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5213 "Should be clear by end of the final marking"); |
|
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5214 assert(_ct->klass_rem_set()->mod_union_is_clear(), |
|
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5215 "Should be clear by end of the final marking"); |
| 0 | 5216 if (UseAdaptiveSizePolicy) { |
| 5217 size_policy()->checkpoint_roots_final_end(gch->gc_cause()); | |
| 5218 } | |
| 5219 } | |
| 5220 | |
| 11975 | 5221 void CMSParInitialMarkTask::work(uint worker_id) { |
| 5222 elapsedTimer _timer; | |
| 5223 ResourceMark rm; | |
| 5224 HandleMark hm; | |
| 5225 | |
| 5226 // ---------- scan from roots -------------- | |
| 5227 _timer.start(); | |
| 5228 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 5229 Par_MarkRefsIntoClosure par_mri_cl(_collector->_span, &(_collector->_markBitMap)); | |
| 5230 CMKlassClosure klass_closure(&par_mri_cl); | |
| 5231 | |
| 5232 // ---------- young gen roots -------------- | |
| 5233 { | |
| 5234 work_on_young_gen_roots(worker_id, &par_mri_cl); | |
| 5235 _timer.stop(); | |
| 5236 if (PrintCMSStatistics != 0) { | |
| 5237 gclog_or_tty->print_cr( | |
| 5238 "Finished young gen initial mark scan work in %dth thread: %3.3f sec", | |
| 5239 worker_id, _timer.seconds()); | |
| 5240 } | |
| 5241 } | |
| 5242 | |
| 5243 // ---------- remaining roots -------------- | |
| 5244 _timer.reset(); | |
| 5245 _timer.start(); | |
| 5246 gch->gen_process_strong_roots(_collector->_cmsGen->level(), | |
| 5247 false, // yg was scanned above | |
| 5248 false, // this is parallel code | |
| 5249 false, // not scavenging | |
| 5250 SharedHeap::ScanningOption(_collector->CMSCollector::roots_scanning_options()), | |
| 5251 &par_mri_cl, | |
| 5252 true, // walk all of code cache if (so & SO_CodeCache) | |
| 5253 NULL, | |
| 5254 &klass_closure); | |
| 5255 assert(_collector->should_unload_classes() | |
| 5256 || (_collector->CMSCollector::roots_scanning_options() & SharedHeap::SO_CodeCache), | |
| 5257 "if we didn't scan the code cache, we have to be ready to drop nmethods with expired weak oops"); | |
| 5258 _timer.stop(); | |
| 5259 if (PrintCMSStatistics != 0) { | |
| 5260 gclog_or_tty->print_cr( | |
| 5261 "Finished remaining root initial mark scan work in %dth thread: %3.3f sec", | |
| 5262 worker_id, _timer.seconds()); | |
| 5263 } | |
| 5264 } | |
| 5265 | |
| 0 | 5266 // Parallel remark task |
| 11975 | 5267 class CMSParRemarkTask: public CMSParMarkTask { |
| 0 | 5268 CompactibleFreeListSpace* _cms_space; |
| 5269 | |
| 5270 // The per-thread work queues, available here for stealing. | |
| 5271 OopTaskQueueSet* _task_queues; | |
| 5272 ParallelTaskTerminator _term; | |
| 5273 | |
| 5274 public: | |
|
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5275 // A value of 0 passed to n_workers will cause the number of |
|
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|
5276 // workers to be taken from the active workers in the work gang. |
| 0 | 5277 CMSParRemarkTask(CMSCollector* collector, |
| 5278 CompactibleFreeListSpace* cms_space, | |
|
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|
5279 int n_workers, FlexibleWorkGang* workers, |
| 0 | 5280 OopTaskQueueSet* task_queues): |
| 11975 | 5281 CMSParMarkTask("Rescan roots and grey objects in parallel", |
| 5282 collector, n_workers), | |
|
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5283 _cms_space(cms_space), |
| 0 | 5284 _task_queues(task_queues), |
|
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|
5285 _term(n_workers, task_queues) { } |
| 0 | 5286 |
| 5287 OopTaskQueueSet* task_queues() { return _task_queues; } | |
| 5288 | |
| 5289 OopTaskQueue* work_queue(int i) { return task_queues()->queue(i); } | |
| 5290 | |
| 5291 ParallelTaskTerminator* terminator() { return &_term; } | |
|
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5292 int n_workers() { return _n_workers; } |
| 0 | 5293 |
|
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|
5294 void work(uint worker_id); |
| 0 | 5295 |
| 5296 private: | |
| 5297 // ... of dirty cards in old space | |
| 5298 void do_dirty_card_rescan_tasks(CompactibleFreeListSpace* sp, int i, | |
| 5299 Par_MarkRefsIntoAndScanClosure* cl); | |
| 5300 | |
| 5301 // ... work stealing for the above | |
| 5302 void do_work_steal(int i, Par_MarkRefsIntoAndScanClosure* cl, int* seed); | |
| 5303 }; | |
| 5304 | |
|
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5305 class RemarkKlassClosure : public KlassClosure { |
|
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|
5306 CMKlassClosure _cm_klass_closure; |
|
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5307 public: |
|
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|
5308 RemarkKlassClosure(OopClosure* oop_closure) : _cm_klass_closure(oop_closure) {} |
|
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5309 void do_klass(Klass* k) { |
|
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5310 // Check if we have modified any oops in the Klass during the concurrent marking. |
|
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5311 if (k->has_accumulated_modified_oops()) { |
|
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5312 k->clear_accumulated_modified_oops(); |
|
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5313 |
|
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5314 // We could have transfered the current modified marks to the accumulated marks, |
|
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5315 // like we do with the Card Table to Mod Union Table. But it's not really necessary. |
|
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5316 } else if (k->has_modified_oops()) { |
|
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5317 // Don't clear anything, this info is needed by the next young collection. |
|
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5318 } else { |
|
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5319 // No modified oops in the Klass. |
|
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5320 return; |
|
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|
5321 } |
|
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|
5322 |
|
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5323 // The klass has modified fields, need to scan the klass. |
|
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5324 _cm_klass_closure.do_klass(k); |
|
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5325 } |
|
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|
5326 }; |
|
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|
5327 |
| 11975 | 5328 void CMSParMarkTask::work_on_young_gen_roots(uint worker_id, OopsInGenClosure* cl) { |
| 5329 DefNewGeneration* dng = _collector->_young_gen->as_DefNewGeneration(); | |
| 5330 EdenSpace* eden_space = dng->eden(); | |
| 5331 ContiguousSpace* from_space = dng->from(); | |
| 5332 ContiguousSpace* to_space = dng->to(); | |
| 5333 | |
| 5334 HeapWord** eca = _collector->_eden_chunk_array; | |
| 5335 size_t ect = _collector->_eden_chunk_index; | |
| 5336 HeapWord** sca = _collector->_survivor_chunk_array; | |
| 5337 size_t sct = _collector->_survivor_chunk_index; | |
| 5338 | |
| 5339 assert(ect <= _collector->_eden_chunk_capacity, "out of bounds"); | |
| 5340 assert(sct <= _collector->_survivor_chunk_capacity, "out of bounds"); | |
| 5341 | |
| 5342 do_young_space_rescan(worker_id, cl, to_space, NULL, 0); | |
| 5343 do_young_space_rescan(worker_id, cl, from_space, sca, sct); | |
| 5344 do_young_space_rescan(worker_id, cl, eden_space, eca, ect); | |
| 5345 } | |
| 5346 | |
|
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|
5347 // work_queue(i) is passed to the closure |
|
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5348 // Par_MarkRefsIntoAndScanClosure. The "i" parameter |
|
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5349 // also is passed to do_dirty_card_rescan_tasks() and to |
|
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5350 // do_work_steal() to select the i-th task_queue. |
|
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5351 |
|
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|
5352 void CMSParRemarkTask::work(uint worker_id) { |
| 0 | 5353 elapsedTimer _timer; |
| 5354 ResourceMark rm; | |
| 5355 HandleMark hm; | |
| 5356 | |
| 5357 // ---------- rescan from roots -------------- | |
| 5358 _timer.start(); | |
| 5359 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 5360 Par_MarkRefsIntoAndScanClosure par_mrias_cl(_collector, | |
| 5361 _collector->_span, _collector->ref_processor(), | |
| 5362 &(_collector->_markBitMap), | |
|
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|
5363 work_queue(worker_id)); |
| 0 | 5364 |
| 5365 // Rescan young gen roots first since these are likely | |
| 5366 // coarsely partitioned and may, on that account, constitute | |
| 5367 // the critical path; thus, it's best to start off that | |
| 5368 // work first. | |
| 5369 // ---------- young gen roots -------------- | |
| 5370 { | |
| 11975 | 5371 work_on_young_gen_roots(worker_id, &par_mrias_cl); |
| 0 | 5372 _timer.stop(); |
| 5373 if (PrintCMSStatistics != 0) { | |
| 5374 gclog_or_tty->print_cr( | |
| 5375 "Finished young gen rescan work in %dth thread: %3.3f sec", | |
|
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|
5376 worker_id, _timer.seconds()); |
| 0 | 5377 } |
| 5378 } | |
| 5379 | |
| 5380 // ---------- remaining roots -------------- | |
| 5381 _timer.reset(); | |
| 5382 _timer.start(); | |
| 5383 gch->gen_process_strong_roots(_collector->_cmsGen->level(), | |
| 5384 false, // yg was scanned above | |
|
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|
5385 false, // this is parallel code |
|
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|
5386 false, // not scavenging |
| 0 | 5387 SharedHeap::ScanningOption(_collector->CMSCollector::roots_scanning_options()), |
|
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|
5388 &par_mrias_cl, |
|
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|
5389 true, // walk all of code cache if (so & SO_CodeCache) |
|
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5390 NULL, |
|
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|
5391 NULL); // The dirty klasses will be handled below |
|
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|
5392 assert(_collector->should_unload_classes() |
|
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|
5393 || (_collector->CMSCollector::roots_scanning_options() & SharedHeap::SO_CodeCache), |
|
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|
5394 "if we didn't scan the code cache, we have to be ready to drop nmethods with expired weak oops"); |
| 0 | 5395 _timer.stop(); |
| 5396 if (PrintCMSStatistics != 0) { | |
| 5397 gclog_or_tty->print_cr( | |
| 5398 "Finished remaining root rescan work in %dth thread: %3.3f sec", | |
|
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|
5399 worker_id, _timer.seconds()); |
| 0 | 5400 } |
| 5401 | |
|
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|
5402 // ---------- unhandled CLD scanning ---------- |
|
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|
5403 if (worker_id == 0) { // Single threaded at the moment. |
|
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|
5404 _timer.reset(); |
|
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|
5405 _timer.start(); |
|
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|
5406 |
|
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|
5407 // Scan all new class loader data objects and new dependencies that were |
|
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|
5408 // introduced during concurrent marking. |
|
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|
5409 ResourceMark rm; |
|
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|
5410 GrowableArray<ClassLoaderData*>* array = ClassLoaderDataGraph::new_clds(); |
|
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|
5411 for (int i = 0; i < array->length(); i++) { |
|
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|
5412 par_mrias_cl.do_class_loader_data(array->at(i)); |
|
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|
5413 } |
|
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|
5414 |
|
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|
5415 // We don't need to keep track of new CLDs anymore. |
|
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|
5416 ClassLoaderDataGraph::remember_new_clds(false); |
|
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|
5417 |
|
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|
5418 _timer.stop(); |
|
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|
5419 if (PrintCMSStatistics != 0) { |
|
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|
5420 gclog_or_tty->print_cr( |
|
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|
5421 "Finished unhandled CLD scanning work in %dth thread: %3.3f sec", |
|
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|
5422 worker_id, _timer.seconds()); |
|
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|
5423 } |
|
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|
5424 } |
|
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|
5425 |
|
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|
5426 // ---------- dirty klass scanning ---------- |
|
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|
5427 if (worker_id == 0) { // Single threaded at the moment. |
|
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|
5428 _timer.reset(); |
|
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|
5429 _timer.start(); |
|
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|
5430 |
|
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|
5431 // Scan all classes that was dirtied during the concurrent marking phase. |
|
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|
5432 RemarkKlassClosure remark_klass_closure(&par_mrias_cl); |
|
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|
5433 ClassLoaderDataGraph::classes_do(&remark_klass_closure); |
|
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|
5434 |
|
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|
5435 _timer.stop(); |
|
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|
5436 if (PrintCMSStatistics != 0) { |
|
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|
5437 gclog_or_tty->print_cr( |
|
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|
5438 "Finished dirty klass scanning work in %dth thread: %3.3f sec", |
|
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|
5439 worker_id, _timer.seconds()); |
|
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|
5440 } |
|
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|
5441 } |
|
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|
5442 |
|
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|
5443 // We might have added oops to ClassLoaderData::_handles during the |
|
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|
5444 // concurrent marking phase. These oops point to newly allocated objects |
|
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|
5445 // that are guaranteed to be kept alive. Either by the direct allocation |
|
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|
5446 // code, or when the young collector processes the strong roots. Hence, |
|
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|
5447 // we don't have to revisit the _handles block during the remark phase. |
|
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|
5448 |
| 0 | 5449 // ---------- rescan dirty cards ------------ |
| 5450 _timer.reset(); | |
| 5451 _timer.start(); | |
| 5452 | |
| 5453 // Do the rescan tasks for each of the two spaces | |
|
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|
5454 // (cms_space) in turn. |
|
4728
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|
5455 // "worker_id" is passed to select the task_queue for "worker_id" |
|
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|
5456 do_dirty_card_rescan_tasks(_cms_space, worker_id, &par_mrias_cl); |
| 0 | 5457 _timer.stop(); |
| 5458 if (PrintCMSStatistics != 0) { | |
| 5459 gclog_or_tty->print_cr( | |
| 5460 "Finished dirty card rescan work in %dth thread: %3.3f sec", | |
|
4728
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changeset
|
5461 worker_id, _timer.seconds()); |
| 0 | 5462 } |
| 5463 | |
| 5464 // ---------- steal work from other threads ... | |
| 5465 // ---------- ... and drain overflow list. | |
| 5466 _timer.reset(); | |
| 5467 _timer.start(); | |
|
4728
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changeset
|
5468 do_work_steal(worker_id, &par_mrias_cl, _collector->hash_seed(worker_id)); |
| 0 | 5469 _timer.stop(); |
| 5470 if (PrintCMSStatistics != 0) { | |
| 5471 gclog_or_tty->print_cr( | |
| 5472 "Finished work stealing in %dth thread: %3.3f sec", | |
|
4728
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changeset
|
5473 worker_id, _timer.seconds()); |
| 0 | 5474 } |
| 5475 } | |
| 5476 | |
|
1833
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|
5477 // Note that parameter "i" is not used. |
| 0 | 5478 void |
| 11975 | 5479 CMSParMarkTask::do_young_space_rescan(uint worker_id, |
| 5480 OopsInGenClosure* cl, ContiguousSpace* space, | |
| 0 | 5481 HeapWord** chunk_array, size_t chunk_top) { |
| 5482 // Until all tasks completed: | |
| 5483 // . claim an unclaimed task | |
| 5484 // . compute region boundaries corresponding to task claimed | |
| 5485 // using chunk_array | |
| 5486 // . par_oop_iterate(cl) over that region | |
| 5487 | |
| 5488 ResourceMark rm; | |
| 5489 HandleMark hm; | |
| 5490 | |
| 5491 SequentialSubTasksDone* pst = space->par_seq_tasks(); | |
| 5492 | |
|
4728
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|
5493 uint nth_task = 0; |
|
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|
5494 uint n_tasks = pst->n_tasks(); |
| 0 | 5495 |
|
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|
5496 if (n_tasks > 0) { |
|
cb9da55b1990
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diff
changeset
|
5497 assert(pst->valid(), "Uninitialized use?"); |
|
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|
5498 HeapWord *start, *end; |
|
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|
5499 while (!pst->is_task_claimed(/* reference */ nth_task)) { |
|
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|
5500 // We claimed task # nth_task; compute its boundaries. |
|
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|
5501 if (chunk_top == 0) { // no samples were taken |
|
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|
5502 assert(nth_task == 0 && n_tasks == 1, "Can have only 1 EdenSpace task"); |
|
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|
5503 start = space->bottom(); |
|
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|
5504 end = space->top(); |
|
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|
5505 } else if (nth_task == 0) { |
|
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|
5506 start = space->bottom(); |
|
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|
5507 end = chunk_array[nth_task]; |
|
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|
5508 } else if (nth_task < (uint)chunk_top) { |
|
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|
5509 assert(nth_task >= 1, "Control point invariant"); |
|
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|
5510 start = chunk_array[nth_task - 1]; |
|
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|
5511 end = chunk_array[nth_task]; |
|
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|
5512 } else { |
|
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|
5513 assert(nth_task == (uint)chunk_top, "Control point invariant"); |
|
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|
5514 start = chunk_array[chunk_top - 1]; |
|
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|
5515 end = space->top(); |
|
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|
5516 } |
|
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|
5517 MemRegion mr(start, end); |
|
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|
5518 // Verify that mr is in space |
|
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|
5519 assert(mr.is_empty() || space->used_region().contains(mr), |
|
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|
5520 "Should be in space"); |
|
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changeset
|
5521 // Verify that "start" is an object boundary |
|
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|
5522 assert(mr.is_empty() || oop(mr.start())->is_oop(), |
|
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|
5523 "Should be an oop"); |
|
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|
5524 space->par_oop_iterate(mr, cl); |
|
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|
5525 } |
|
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|
5526 pst->all_tasks_completed(); |
|
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|
5527 } |
| 0 | 5528 } |
| 5529 | |
| 5530 void | |
| 5531 CMSParRemarkTask::do_dirty_card_rescan_tasks( | |
| 5532 CompactibleFreeListSpace* sp, int i, | |
| 5533 Par_MarkRefsIntoAndScanClosure* cl) { | |
| 5534 // Until all tasks completed: | |
| 5535 // . claim an unclaimed task | |
| 5536 // . compute region boundaries corresponding to task claimed | |
| 5537 // . transfer dirty bits ct->mut for that region | |
| 5538 // . apply rescanclosure to dirty mut bits for that region | |
| 5539 | |
| 5540 ResourceMark rm; | |
| 5541 HandleMark hm; | |
| 5542 | |
| 5543 OopTaskQueue* work_q = work_queue(i); | |
| 5544 ModUnionClosure modUnionClosure(&(_collector->_modUnionTable)); | |
| 5545 // CAUTION! CAUTION! CAUTION! CAUTION! CAUTION! CAUTION! CAUTION! | |
| 5546 // CAUTION: This closure has state that persists across calls to | |
| 5547 // the work method dirty_range_iterate_clear() in that it has | |
| 5548 // imbedded in it a (subtype of) UpwardsObjectClosure. The | |
| 5549 // use of that state in the imbedded UpwardsObjectClosure instance | |
| 5550 // assumes that the cards are always iterated (even if in parallel | |
| 5551 // by several threads) in monotonically increasing order per each | |
| 5552 // thread. This is true of the implementation below which picks | |
| 5553 // card ranges (chunks) in monotonically increasing order globally | |
| 5554 // and, a-fortiori, in monotonically increasing order per thread | |
| 5555 // (the latter order being a subsequence of the former). | |
| 5556 // If the work code below is ever reorganized into a more chaotic | |
| 5557 // work-partitioning form than the current "sequential tasks" | |
| 5558 // paradigm, the use of that persistent state will have to be | |
| 5559 // revisited and modified appropriately. See also related | |
| 5560 // bug 4756801 work on which should examine this code to make | |
| 5561 // sure that the changes there do not run counter to the | |
| 5562 // assumptions made here and necessary for correctness and | |
| 5563 // efficiency. Note also that this code might yield inefficient | |
| 5564 // behaviour in the case of very large objects that span one or | |
| 5565 // more work chunks. Such objects would potentially be scanned | |
| 5566 // several times redundantly. Work on 4756801 should try and | |
| 5567 // address that performance anomaly if at all possible. XXX | |
| 5568 MemRegion full_span = _collector->_span; | |
| 5569 CMSBitMap* bm = &(_collector->_markBitMap); // shared | |
| 5570 MarkFromDirtyCardsClosure | |
| 5571 greyRescanClosure(_collector, full_span, // entire span of interest | |
|
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5572 sp, bm, work_q, cl); |
| 0 | 5573 |
| 5574 SequentialSubTasksDone* pst = sp->conc_par_seq_tasks(); | |
| 5575 assert(pst->valid(), "Uninitialized use?"); | |
|
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|
5576 uint nth_task = 0; |
| 0 | 5577 const int alignment = CardTableModRefBS::card_size * BitsPerWord; |
| 5578 MemRegion span = sp->used_region(); | |
| 5579 HeapWord* start_addr = span.start(); | |
| 5580 HeapWord* end_addr = (HeapWord*)round_to((intptr_t)span.end(), | |
| 5581 alignment); | |
| 5582 const size_t chunk_size = sp->rescan_task_size(); // in HeapWord units | |
| 5583 assert((HeapWord*)round_to((intptr_t)start_addr, alignment) == | |
| 5584 start_addr, "Check alignment"); | |
| 5585 assert((size_t)round_to((intptr_t)chunk_size, alignment) == | |
| 5586 chunk_size, "Check alignment"); | |
| 5587 | |
| 5588 while (!pst->is_task_claimed(/* reference */ nth_task)) { | |
| 5589 // Having claimed the nth_task, compute corresponding mem-region, | |
| 5590 // which is a-fortiori aligned correctly (i.e. at a MUT bopundary). | |
| 5591 // The alignment restriction ensures that we do not need any | |
| 5592 // synchronization with other gang-workers while setting or | |
| 5593 // clearing bits in thus chunk of the MUT. | |
| 5594 MemRegion this_span = MemRegion(start_addr + nth_task*chunk_size, | |
| 5595 start_addr + (nth_task+1)*chunk_size); | |
| 5596 // The last chunk's end might be way beyond end of the | |
| 5597 // used region. In that case pull back appropriately. | |
| 5598 if (this_span.end() > end_addr) { | |
| 5599 this_span.set_end(end_addr); | |
| 5600 assert(!this_span.is_empty(), "Program logic (calculation of n_tasks)"); | |
| 5601 } | |
| 5602 // Iterate over the dirty cards covering this chunk, marking them | |
| 5603 // precleaned, and setting the corresponding bits in the mod union | |
| 5604 // table. Since we have been careful to partition at Card and MUT-word | |
| 5605 // boundaries no synchronization is needed between parallel threads. | |
| 5606 _collector->_ct->ct_bs()->dirty_card_iterate(this_span, | |
| 5607 &modUnionClosure); | |
| 5608 | |
| 5609 // Having transferred these marks into the modUnionTable, | |
| 5610 // rescan the marked objects on the dirty cards in the modUnionTable. | |
| 5611 // Even if this is at a synchronous collection, the initial marking | |
| 5612 // may have been done during an asynchronous collection so there | |
| 5613 // may be dirty bits in the mod-union table. | |
| 5614 _collector->_modUnionTable.dirty_range_iterate_clear( | |
| 5615 this_span, &greyRescanClosure); | |
| 5616 _collector->_modUnionTable.verifyNoOneBitsInRange( | |
| 5617 this_span.start(), | |
| 5618 this_span.end()); | |
| 5619 } | |
| 5620 pst->all_tasks_completed(); // declare that i am done | |
| 5621 } | |
| 5622 | |
| 5623 // . see if we can share work_queues with ParNew? XXX | |
| 5624 void | |
| 5625 CMSParRemarkTask::do_work_steal(int i, Par_MarkRefsIntoAndScanClosure* cl, | |
| 5626 int* seed) { | |
| 5627 OopTaskQueue* work_q = work_queue(i); | |
| 5628 NOT_PRODUCT(int num_steals = 0;) | |
| 5629 oop obj_to_scan; | |
| 5630 CMSBitMap* bm = &(_collector->_markBitMap); | |
| 5631 | |
| 5632 while (true) { | |
| 5633 // Completely finish any left over work from (an) earlier round(s) | |
| 5634 cl->trim_queue(0); | |
|
679
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diff
changeset
|
5635 size_t num_from_overflow_list = MIN2((size_t)(work_q->max_elems() - work_q->size())/4, |
|
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|
5636 (size_t)ParGCDesiredObjsFromOverflowList); |
| 0 | 5637 // Now check if there's any work in the overflow list |
|
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|
5638 // Passing ParallelGCThreads as the third parameter, no_of_gc_threads, |
|
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|
5639 // only affects the number of attempts made to get work from the |
|
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|
5640 // overflow list and does not affect the number of workers. Just |
|
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|
5641 // pass ParallelGCThreads so this behavior is unchanged. |
| 0 | 5642 if (_collector->par_take_from_overflow_list(num_from_overflow_list, |
|
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|
5643 work_q, |
|
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|
5644 ParallelGCThreads)) { |
| 0 | 5645 // found something in global overflow list; |
| 5646 // not yet ready to go stealing work from others. | |
| 5647 // We'd like to assert(work_q->size() != 0, ...) | |
| 5648 // because we just took work from the overflow list, | |
| 5649 // but of course we can't since all of that could have | |
| 5650 // been already stolen from us. | |
| 5651 // "He giveth and He taketh away." | |
| 5652 continue; | |
| 5653 } | |
| 5654 // Verify that we have no work before we resort to stealing | |
| 5655 assert(work_q->size() == 0, "Have work, shouldn't steal"); | |
| 5656 // Try to steal from other queues that have work | |
| 5657 if (task_queues()->steal(i, seed, /* reference */ obj_to_scan)) { | |
| 5658 NOT_PRODUCT(num_steals++;) | |
| 5659 assert(obj_to_scan->is_oop(), "Oops, not an oop!"); | |
| 5660 assert(bm->isMarked((HeapWord*)obj_to_scan), "Stole an unmarked oop?"); | |
| 5661 // Do scanning work | |
| 5662 obj_to_scan->oop_iterate(cl); | |
| 5663 // Loop around, finish this work, and try to steal some more | |
| 5664 } else if (terminator()->offer_termination()) { | |
| 5665 break; // nirvana from the infinite cycle | |
| 5666 } | |
| 5667 } | |
| 5668 NOT_PRODUCT( | |
| 5669 if (PrintCMSStatistics != 0) { | |
| 5670 gclog_or_tty->print("\n\t(%d: stole %d oops)", i, num_steals); | |
| 5671 } | |
| 5672 ) | |
| 5673 assert(work_q->size() == 0 && _collector->overflow_list_is_empty(), | |
| 5674 "Else our work is not yet done"); | |
| 5675 } | |
| 5676 | |
|
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|
5677 // Record object boundaries in _eden_chunk_array by sampling the eden |
|
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|
5678 // top in the slow-path eden object allocation code path and record |
|
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|
5679 // the boundaries, if CMSEdenChunksRecordAlways is true. If |
|
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|
5680 // CMSEdenChunksRecordAlways is false, we use the other asynchronous |
|
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|
5681 // sampling in sample_eden() that activates during the part of the |
|
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|
5682 // preclean phase. |
|
7b06ae405d7b
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|
5683 void CMSCollector::sample_eden_chunk() { |
|
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|
5684 if (CMSEdenChunksRecordAlways && _eden_chunk_array != NULL) { |
|
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|
5685 if (_eden_chunk_lock->try_lock()) { |
|
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|
5686 // Record a sample. This is the critical section. The contents |
|
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|
5687 // of the _eden_chunk_array have to be non-decreasing in the |
|
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|
5688 // address order. |
|
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|
5689 _eden_chunk_array[_eden_chunk_index] = *_top_addr; |
|
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|
5690 assert(_eden_chunk_array[_eden_chunk_index] <= *_end_addr, |
|
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|
5691 "Unexpected state of Eden"); |
|
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|
5692 if (_eden_chunk_index == 0 || |
|
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|
5693 ((_eden_chunk_array[_eden_chunk_index] > _eden_chunk_array[_eden_chunk_index-1]) && |
|
7b06ae405d7b
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|
5694 (pointer_delta(_eden_chunk_array[_eden_chunk_index], |
|
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|
5695 _eden_chunk_array[_eden_chunk_index-1]) >= CMSSamplingGrain))) { |
|
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|
5696 _eden_chunk_index++; // commit sample |
|
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|
5697 } |
|
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|
5698 _eden_chunk_lock->unlock(); |
|
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|
5699 } |
|
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|
5700 } |
|
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|
5701 } |
|
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|
5702 |
| 0 | 5703 // Return a thread-local PLAB recording array, as appropriate. |
| 5704 void* CMSCollector::get_data_recorder(int thr_num) { | |
| 5705 if (_survivor_plab_array != NULL && | |
| 5706 (CMSPLABRecordAlways || | |
| 5707 (_collectorState > Marking && _collectorState < FinalMarking))) { | |
| 5708 assert(thr_num < (int)ParallelGCThreads, "thr_num is out of bounds"); | |
| 5709 ChunkArray* ca = &_survivor_plab_array[thr_num]; | |
| 5710 ca->reset(); // clear it so that fresh data is recorded | |
| 5711 return (void*) ca; | |
| 5712 } else { | |
| 5713 return NULL; | |
| 5714 } | |
| 5715 } | |
| 5716 | |
| 5717 // Reset all the thread-local PLAB recording arrays | |
| 5718 void CMSCollector::reset_survivor_plab_arrays() { | |
| 5719 for (uint i = 0; i < ParallelGCThreads; i++) { | |
| 5720 _survivor_plab_array[i].reset(); | |
| 5721 } | |
| 5722 } | |
| 5723 | |
| 5724 // Merge the per-thread plab arrays into the global survivor chunk | |
| 5725 // array which will provide the partitioning of the survivor space | |
| 11975 | 5726 // for CMS initial scan and rescan. |
|
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|
5727 void CMSCollector::merge_survivor_plab_arrays(ContiguousSpace* surv, |
|
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|
5728 int no_of_gc_threads) { |
| 0 | 5729 assert(_survivor_plab_array != NULL, "Error"); |
| 5730 assert(_survivor_chunk_array != NULL, "Error"); | |
| 11975 | 5731 assert(_collectorState == FinalMarking || |
| 5732 (CMSParallelInitialMarkEnabled && _collectorState == InitialMarking), "Error"); | |
|
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|
5733 for (int j = 0; j < no_of_gc_threads; j++) { |
| 0 | 5734 _cursor[j] = 0; |
| 5735 } | |
| 5736 HeapWord* top = surv->top(); | |
| 5737 size_t i; | |
| 5738 for (i = 0; i < _survivor_chunk_capacity; i++) { // all sca entries | |
| 5739 HeapWord* min_val = top; // Higher than any PLAB address | |
| 5740 uint min_tid = 0; // position of min_val this round | |
|
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|
5741 for (int j = 0; j < no_of_gc_threads; j++) { |
| 0 | 5742 ChunkArray* cur_sca = &_survivor_plab_array[j]; |
| 5743 if (_cursor[j] == cur_sca->end()) { | |
| 5744 continue; | |
| 5745 } | |
| 5746 assert(_cursor[j] < cur_sca->end(), "ctl pt invariant"); | |
| 5747 HeapWord* cur_val = cur_sca->nth(_cursor[j]); | |
| 5748 assert(surv->used_region().contains(cur_val), "Out of bounds value"); | |
| 5749 if (cur_val < min_val) { | |
| 5750 min_tid = j; | |
| 5751 min_val = cur_val; | |
| 5752 } else { | |
| 5753 assert(cur_val < top, "All recorded addresses should be less"); | |
| 5754 } | |
| 5755 } | |
| 5756 // At this point min_val and min_tid are respectively | |
| 5757 // the least address in _survivor_plab_array[j]->nth(_cursor[j]) | |
| 5758 // and the thread (j) that witnesses that address. | |
| 5759 // We record this address in the _survivor_chunk_array[i] | |
| 5760 // and increment _cursor[min_tid] prior to the next round i. | |
| 5761 if (min_val == top) { | |
| 5762 break; | |
| 5763 } | |
| 5764 _survivor_chunk_array[i] = min_val; | |
| 5765 _cursor[min_tid]++; | |
| 5766 } | |
| 5767 // We are all done; record the size of the _survivor_chunk_array | |
| 5768 _survivor_chunk_index = i; // exclusive: [0, i) | |
| 5769 if (PrintCMSStatistics > 0) { | |
| 5770 gclog_or_tty->print(" (Survivor:" SIZE_FORMAT "chunks) ", i); | |
| 5771 } | |
| 5772 // Verify that we used up all the recorded entries | |
| 5773 #ifdef ASSERT | |
| 5774 size_t total = 0; | |
|
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|
5775 for (int j = 0; j < no_of_gc_threads; j++) { |
| 0 | 5776 assert(_cursor[j] == _survivor_plab_array[j].end(), "Ctl pt invariant"); |
| 5777 total += _cursor[j]; | |
| 5778 } | |
| 5779 assert(total == _survivor_chunk_index, "Ctl Pt Invariant"); | |
| 5780 // Check that the merged array is in sorted order | |
| 5781 if (total > 0) { | |
| 5782 for (size_t i = 0; i < total - 1; i++) { | |
| 5783 if (PrintCMSStatistics > 0) { | |
| 5784 gclog_or_tty->print(" (chunk" SIZE_FORMAT ":" INTPTR_FORMAT ") ", | |
| 5785 i, _survivor_chunk_array[i]); | |
| 5786 } | |
| 5787 assert(_survivor_chunk_array[i] < _survivor_chunk_array[i+1], | |
| 5788 "Not sorted"); | |
| 5789 } | |
| 5790 } | |
| 5791 #endif // ASSERT | |
| 5792 } | |
| 5793 | |
| 5794 // Set up the space's par_seq_tasks structure for work claiming | |
| 11975 | 5795 // for parallel initial scan and rescan of young gen. |
| 0 | 5796 // See ParRescanTask where this is currently used. |
| 5797 void | |
| 5798 CMSCollector:: | |
| 5799 initialize_sequential_subtasks_for_young_gen_rescan(int n_threads) { | |
| 5800 assert(n_threads > 0, "Unexpected n_threads argument"); | |
| 5801 DefNewGeneration* dng = (DefNewGeneration*)_young_gen; | |
| 5802 | |
| 5803 // Eden space | |
|
12088
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|
5804 if (!dng->eden()->is_empty()) { |
| 0 | 5805 SequentialSubTasksDone* pst = dng->eden()->par_seq_tasks(); |
| 5806 assert(!pst->valid(), "Clobbering existing data?"); | |
| 5807 // Each valid entry in [0, _eden_chunk_index) represents a task. | |
| 5808 size_t n_tasks = _eden_chunk_index + 1; | |
| 5809 assert(n_tasks == 1 || _eden_chunk_array != NULL, "Error"); | |
|
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|
5810 // Sets the condition for completion of the subtask (how many threads |
|
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|
5811 // need to finish in order to be done). |
|
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|
5812 pst->set_n_threads(n_threads); |
| 0 | 5813 pst->set_n_tasks((int)n_tasks); |
| 5814 } | |
| 5815 | |
| 5816 // Merge the survivor plab arrays into _survivor_chunk_array | |
| 5817 if (_survivor_plab_array != NULL) { | |
|
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|
5818 merge_survivor_plab_arrays(dng->from(), n_threads); |
| 0 | 5819 } else { |
| 5820 assert(_survivor_chunk_index == 0, "Error"); | |
| 5821 } | |
| 5822 | |
| 5823 // To space | |
| 5824 { | |
| 5825 SequentialSubTasksDone* pst = dng->to()->par_seq_tasks(); | |
| 5826 assert(!pst->valid(), "Clobbering existing data?"); | |
|
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|
5827 // Sets the condition for completion of the subtask (how many threads |
|
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|
5828 // need to finish in order to be done). |
|
8b10f48633dc
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jmasa
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diff
changeset
|
5829 pst->set_n_threads(n_threads); |
| 0 | 5830 pst->set_n_tasks(1); |
| 5831 assert(pst->valid(), "Error"); | |
| 5832 } | |
| 5833 | |
| 5834 // From space | |
| 5835 { | |
| 5836 SequentialSubTasksDone* pst = dng->from()->par_seq_tasks(); | |
| 5837 assert(!pst->valid(), "Clobbering existing data?"); | |
| 5838 size_t n_tasks = _survivor_chunk_index + 1; | |
| 5839 assert(n_tasks == 1 || _survivor_chunk_array != NULL, "Error"); | |
|
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|
5840 // Sets the condition for completion of the subtask (how many threads |
|
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1777
diff
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|
5841 // need to finish in order to be done). |
|
8b10f48633dc
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1777
diff
changeset
|
5842 pst->set_n_threads(n_threads); |
| 0 | 5843 pst->set_n_tasks((int)n_tasks); |
| 5844 assert(pst->valid(), "Error"); | |
| 5845 } | |
| 5846 } | |
| 5847 | |
| 5848 // Parallel version of remark | |
| 5849 void CMSCollector::do_remark_parallel() { | |
| 5850 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
|
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|
5851 FlexibleWorkGang* workers = gch->workers(); |
| 0 | 5852 assert(workers != NULL, "Need parallel worker threads."); |
|
4095
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
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3979
diff
changeset
|
5853 // Choose to use the number of GC workers most recently set |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
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3979
diff
changeset
|
5854 // into "active_workers". If active_workers is not set, set it |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
parents:
3979
diff
changeset
|
5855 // to ParallelGCThreads. |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
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3979
diff
changeset
|
5856 int n_workers = workers->active_workers(); |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
parents:
3979
diff
changeset
|
5857 if (n_workers == 0) { |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
parents:
3979
diff
changeset
|
5858 assert(n_workers > 0, "Should have been set during scavenge"); |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
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3979
diff
changeset
|
5859 n_workers = ParallelGCThreads; |
|
bca17e38de00
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jmasa
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3979
diff
changeset
|
5860 workers->set_active_workers(n_workers); |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
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3979
diff
changeset
|
5861 } |
| 0 | 5862 CompactibleFreeListSpace* cms_space = _cmsGen->cmsSpace(); |
| 5863 | |
| 5864 CMSParRemarkTask tsk(this, | |
|
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diff
changeset
|
5865 cms_space, |
| 0 | 5866 n_workers, workers, task_queues()); |
| 5867 | |
| 5868 // Set up for parallel process_strong_roots work. | |
| 5869 gch->set_par_threads(n_workers); | |
| 5870 // We won't be iterating over the cards in the card table updating | |
| 5871 // the younger_gen cards, so we shouldn't call the following else | |
| 5872 // the verification code as well as subsequent younger_refs_iterate | |
| 5873 // code would get confused. XXX | |
| 5874 // gch->rem_set()->prepare_for_younger_refs_iterate(true); // parallel | |
| 5875 | |
| 5876 // The young gen rescan work will not be done as part of | |
| 5877 // process_strong_roots (which currently doesn't knw how to | |
| 5878 // parallelize such a scan), but rather will be broken up into | |
| 5879 // a set of parallel tasks (via the sampling that the [abortable] | |
| 5880 // preclean phase did of EdenSpace, plus the [two] tasks of | |
| 5881 // scanning the [two] survivor spaces. Further fine-grain | |
| 5882 // parallelization of the scanning of the survivor spaces | |
| 5883 // themselves, and of precleaning of the younger gen itself | |
| 5884 // is deferred to the future. | |
| 5885 initialize_sequential_subtasks_for_young_gen_rescan(n_workers); | |
| 5886 | |
| 5887 // The dirty card rescan work is broken up into a "sequence" | |
| 5888 // of parallel tasks (per constituent space) that are dynamically | |
| 5889 // claimed by the parallel threads. | |
| 5890 cms_space->initialize_sequential_subtasks_for_rescan(n_workers); | |
| 5891 | |
| 5892 // It turns out that even when we're using 1 thread, doing the work in a | |
| 5893 // separate thread causes wide variance in run times. We can't help this | |
| 5894 // in the multi-threaded case, but we special-case n=1 here to get | |
| 5895 // repeatable measurements of the 1-thread overhead of the parallel code. | |
| 5896 if (n_workers > 1) { | |
|
2369
92da084fefc9
6668573: CMS: reference processing crash if ParallelCMSThreads > ParallelGCThreads
ysr
parents:
2365
diff
changeset
|
5897 // Make refs discovery MT-safe, if it isn't already: it may not |
|
92da084fefc9
6668573: CMS: reference processing crash if ParallelCMSThreads > ParallelGCThreads
ysr
parents:
2365
diff
changeset
|
5898 // necessarily be so, since it's possible that we are doing |
|
92da084fefc9
6668573: CMS: reference processing crash if ParallelCMSThreads > ParallelGCThreads
ysr
parents:
2365
diff
changeset
|
5899 // ST marking. |
|
92da084fefc9
6668573: CMS: reference processing crash if ParallelCMSThreads > ParallelGCThreads
ysr
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2365
diff
changeset
|
5900 ReferenceProcessorMTDiscoveryMutator mt(ref_processor(), true); |
|
989
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6863023: need non-perm oops in code cache for JSR 292
jrose
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798
diff
changeset
|
5901 GenCollectedHeap::StrongRootsScope srs(gch); |
| 0 | 5902 workers->run_task(&tsk); |
| 5903 } else { | |
|
4876
be649fefcdc2
7134655: Crash in reference processing when doing single-threaded remarking
stefank
parents:
4728
diff
changeset
|
5904 ReferenceProcessorMTDiscoveryMutator mt(ref_processor(), false); |
|
989
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
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798
diff
changeset
|
5905 GenCollectedHeap::StrongRootsScope srs(gch); |
| 0 | 5906 tsk.work(0); |
| 5907 } | |
|
6725
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diff
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|
5908 |
| 0 | 5909 gch->set_par_threads(0); // 0 ==> non-parallel. |
| 5910 // restore, single-threaded for now, any preserved marks | |
| 5911 // as a result of work_q overflow | |
| 5912 restore_preserved_marks_if_any(); | |
| 5913 } | |
| 5914 | |
| 5915 // Non-parallel version of remark | |
| 5916 void CMSCollector::do_remark_non_parallel() { | |
| 5917 ResourceMark rm; | |
| 5918 HandleMark hm; | |
| 5919 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
|
4876
be649fefcdc2
7134655: Crash in reference processing when doing single-threaded remarking
stefank
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4728
diff
changeset
|
5920 ReferenceProcessorMTDiscoveryMutator mt(ref_processor(), false); |
|
be649fefcdc2
7134655: Crash in reference processing when doing single-threaded remarking
stefank
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4728
diff
changeset
|
5921 |
| 0 | 5922 MarkRefsIntoAndScanClosure |
|
6725
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6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
5923 mrias_cl(_span, ref_processor(), &_markBitMap, NULL /* not precleaning */, |
|
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coleenp
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diff
changeset
|
5924 &_markStack, this, |
| 0 | 5925 false /* should_yield */, false /* not precleaning */); |
| 5926 MarkFromDirtyCardsClosure | |
| 5927 markFromDirtyCardsClosure(this, _span, | |
| 5928 NULL, // space is set further below | |
|
6725
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
5929 &_markBitMap, &_markStack, &mrias_cl); |
| 0 | 5930 { |
| 10405 | 5931 GCTraceTime t("grey object rescan", PrintGCDetails, false, _gc_timer_cm); |
|
342
37f87013dfd8
6711316: Open source the Garbage-First garbage collector
ysr
parents:
143
diff
changeset
|
5932 // Iterate over the dirty cards, setting the corresponding bits in the |
|
37f87013dfd8
6711316: Open source the Garbage-First garbage collector
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143
diff
changeset
|
5933 // mod union table. |
| 0 | 5934 { |
| 5935 ModUnionClosure modUnionClosure(&_modUnionTable); | |
| 5936 _ct->ct_bs()->dirty_card_iterate( | |
| 5937 _cmsGen->used_region(), | |
| 5938 &modUnionClosure); | |
| 5939 } | |
| 5940 // Having transferred these marks into the modUnionTable, we just need | |
| 5941 // to rescan the marked objects on the dirty cards in the modUnionTable. | |
| 5942 // The initial marking may have been done during an asynchronous | |
| 5943 // collection so there may be dirty bits in the mod-union table. | |
| 5944 const int alignment = | |
| 5945 CardTableModRefBS::card_size * BitsPerWord; | |
| 5946 { | |
| 5947 // ... First handle dirty cards in CMS gen | |
| 5948 markFromDirtyCardsClosure.set_space(_cmsGen->cmsSpace()); | |
| 5949 MemRegion ur = _cmsGen->used_region(); | |
| 5950 HeapWord* lb = ur.start(); | |
| 5951 HeapWord* ub = (HeapWord*)round_to((intptr_t)ur.end(), alignment); | |
| 5952 MemRegion cms_span(lb, ub); | |
| 5953 _modUnionTable.dirty_range_iterate_clear(cms_span, | |
| 5954 &markFromDirtyCardsClosure); | |
| 5955 verify_work_stacks_empty(); | |
| 5956 if (PrintCMSStatistics != 0) { | |
| 5957 gclog_or_tty->print(" (re-scanned "SIZE_FORMAT" dirty cards in cms gen) ", | |
| 5958 markFromDirtyCardsClosure.num_dirty_cards()); | |
| 5959 } | |
| 5960 } | |
| 5961 } | |
| 5962 if (VerifyDuringGC && | |
| 5963 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
| 5964 HandleMark hm; // Discard invalid handles created during verification | |
|
6865
4202510ee0fe
8000831: Heap verification output incorrect/incomplete
johnc
parents:
6787
diff
changeset
|
5965 Universe::verify(); |
| 0 | 5966 } |
| 5967 { | |
| 10405 | 5968 GCTraceTime t("root rescan", PrintGCDetails, false, _gc_timer_cm); |
| 0 | 5969 |
| 5970 verify_work_stacks_empty(); | |
| 5971 | |
| 5972 gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel. | |
|
989
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6863023: need non-perm oops in code cache for JSR 292
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798
diff
changeset
|
5973 GenCollectedHeap::StrongRootsScope srs(gch); |
| 0 | 5974 gch->gen_process_strong_roots(_cmsGen->level(), |
| 5975 true, // younger gens as roots | |
|
989
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6863023: need non-perm oops in code cache for JSR 292
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diff
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|
5976 false, // use the local StrongRootsScope |
|
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|
5977 false, // not scavenging |
| 0 | 5978 SharedHeap::ScanningOption(roots_scanning_options()), |
|
989
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6863023: need non-perm oops in code cache for JSR 292
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798
diff
changeset
|
5979 &mrias_cl, |
|
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798
diff
changeset
|
5980 true, // walk code active on stacks |
|
6725
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6197
diff
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|
5981 NULL, |
|
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|
5982 NULL); // The dirty klasses will be handled below |
|
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6197
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|
5983 |
|
989
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6863023: need non-perm oops in code cache for JSR 292
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798
diff
changeset
|
5984 assert(should_unload_classes() |
|
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6863023: need non-perm oops in code cache for JSR 292
jrose
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798
diff
changeset
|
5985 || (roots_scanning_options() & SharedHeap::SO_CodeCache), |
|
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798
diff
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|
5986 "if we didn't scan the code cache, we have to be ready to drop nmethods with expired weak oops"); |
| 0 | 5987 } |
|
6725
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|
5988 |
|
da91efe96a93
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|
5989 { |
| 10405 | 5990 GCTraceTime t("visit unhandled CLDs", PrintGCDetails, false, _gc_timer_cm); |
|
6725
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|
5991 |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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changeset
|
5992 verify_work_stacks_empty(); |
|
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coleenp
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6197
diff
changeset
|
5993 |
|
da91efe96a93
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6197
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|
5994 // Scan all class loader data objects that might have been introduced |
|
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6197
diff
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|
5995 // during concurrent marking. |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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6197
diff
changeset
|
5996 ResourceMark rm; |
|
da91efe96a93
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diff
changeset
|
5997 GrowableArray<ClassLoaderData*>* array = ClassLoaderDataGraph::new_clds(); |
|
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coleenp
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6197
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changeset
|
5998 for (int i = 0; i < array->length(); i++) { |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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6197
diff
changeset
|
5999 mrias_cl.do_class_loader_data(array->at(i)); |
|
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6000 } |
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6001 |
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|
6002 // We don't need to keep track of new CLDs anymore. |
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6003 ClassLoaderDataGraph::remember_new_clds(false); |
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6004 |
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6005 verify_work_stacks_empty(); |
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6006 } |
|
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|
6007 |
|
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6008 { |
| 10405 | 6009 GCTraceTime t("dirty klass scan", PrintGCDetails, false, _gc_timer_cm); |
|
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6010 |
|
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6011 verify_work_stacks_empty(); |
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6012 |
|
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|
6013 RemarkKlassClosure remark_klass_closure(&mrias_cl); |
|
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6014 ClassLoaderDataGraph::classes_do(&remark_klass_closure); |
|
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6015 |
|
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6016 verify_work_stacks_empty(); |
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|
6017 } |
|
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|
6018 |
|
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|
6019 // We might have added oops to ClassLoaderData::_handles during the |
|
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|
6020 // concurrent marking phase. These oops point to newly allocated objects |
|
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6021 // that are guaranteed to be kept alive. Either by the direct allocation |
|
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6022 // code, or when the young collector processes the strong roots. Hence, |
|
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6023 // we don't have to revisit the _handles block during the remark phase. |
|
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6024 |
| 0 | 6025 verify_work_stacks_empty(); |
| 6026 // Restore evacuated mark words, if any, used for overflow list links | |
| 6027 if (!CMSOverflowEarlyRestoration) { | |
| 6028 restore_preserved_marks_if_any(); | |
| 6029 } | |
| 6030 verify_overflow_empty(); | |
| 6031 } | |
| 6032 | |
| 6033 //////////////////////////////////////////////////////// | |
| 6034 // Parallel Reference Processing Task Proxy Class | |
| 6035 //////////////////////////////////////////////////////// | |
|
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6036 class CMSRefProcTaskProxy: public AbstractGangTaskWOopQueues { |
| 0 | 6037 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; |
| 6038 CMSCollector* _collector; | |
| 6039 CMSBitMap* _mark_bit_map; | |
|
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6040 const MemRegion _span; |
| 0 | 6041 ProcessTask& _task; |
| 6042 | |
| 6043 public: | |
| 6044 CMSRefProcTaskProxy(ProcessTask& task, | |
| 6045 CMSCollector* collector, | |
| 6046 const MemRegion& span, | |
| 6047 CMSBitMap* mark_bit_map, | |
|
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|
6048 AbstractWorkGang* workers, |
| 0 | 6049 OopTaskQueueSet* task_queues): |
|
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6050 // XXX Should superclass AGTWOQ also know about AWG since it knows |
|
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6051 // about the task_queues used by the AWG? Then it could initialize |
|
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6052 // the terminator() object. See 6984287. The set_for_termination() |
|
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|
6053 // below is a temporary band-aid for the regression in 6984287. |
|
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6054 AbstractGangTaskWOopQueues("Process referents by policy in parallel", |
|
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|
6055 task_queues), |
| 0 | 6056 _task(task), |
|
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6057 _collector(collector), _span(span), _mark_bit_map(mark_bit_map) |
|
2369
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|
6058 { |
|
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|
6059 assert(_collector->_span.equals(_span) && !_span.is_empty(), |
|
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|
6060 "Inconsistency in _span"); |
|
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|
6061 set_for_termination(workers->active_workers()); |
|
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|
6062 } |
| 0 | 6063 |
|
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|
6064 OopTaskQueueSet* task_queues() { return queues(); } |
| 0 | 6065 |
| 6066 OopTaskQueue* work_queue(int i) { return task_queues()->queue(i); } | |
| 6067 | |
| 6068 void do_work_steal(int i, | |
| 6069 CMSParDrainMarkingStackClosure* drain, | |
| 6070 CMSParKeepAliveClosure* keep_alive, | |
| 6071 int* seed); | |
| 6072 | |
|
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|
6073 virtual void work(uint worker_id); |
| 0 | 6074 }; |
| 6075 | |
|
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|
6076 void CMSRefProcTaskProxy::work(uint worker_id) { |
|
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|
6077 assert(_collector->_span.equals(_span), "Inconsistency in _span"); |
| 0 | 6078 CMSParKeepAliveClosure par_keep_alive(_collector, _span, |
| 935 | 6079 _mark_bit_map, |
|
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|
6080 work_queue(worker_id)); |
| 0 | 6081 CMSParDrainMarkingStackClosure par_drain_stack(_collector, _span, |
| 935 | 6082 _mark_bit_map, |
|
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|
6083 work_queue(worker_id)); |
|
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|
6084 CMSIsAliveClosure is_alive_closure(_span, _mark_bit_map); |
|
4728
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|
6085 _task.work(worker_id, is_alive_closure, par_keep_alive, par_drain_stack); |
| 0 | 6086 if (_task.marks_oops_alive()) { |
|
4728
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|
6087 do_work_steal(worker_id, &par_drain_stack, &par_keep_alive, |
|
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|
6088 _collector->hash_seed(worker_id)); |
|
441e946dc1af
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|
6089 } |
|
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|
6090 assert(work_queue(worker_id)->size() == 0, "work_queue should be empty"); |
| 0 | 6091 assert(_collector->_overflow_list == NULL, "non-empty _overflow_list"); |
| 6092 } | |
| 6093 | |
| 6094 class CMSRefEnqueueTaskProxy: public AbstractGangTask { | |
| 6095 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; | |
| 6096 EnqueueTask& _task; | |
| 6097 | |
| 6098 public: | |
| 6099 CMSRefEnqueueTaskProxy(EnqueueTask& task) | |
| 6100 : AbstractGangTask("Enqueue reference objects in parallel"), | |
| 6101 _task(task) | |
| 6102 { } | |
| 6103 | |
|
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|
6104 virtual void work(uint worker_id) |
| 0 | 6105 { |
|
4728
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|
6106 _task.work(worker_id); |
| 0 | 6107 } |
| 6108 }; | |
| 6109 | |
| 6110 CMSParKeepAliveClosure::CMSParKeepAliveClosure(CMSCollector* collector, | |
|
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|
6111 MemRegion span, CMSBitMap* bit_map, OopTaskQueue* work_queue): |
| 0 | 6112 _span(span), |
| 6113 _bit_map(bit_map), | |
| 6114 _work_queue(work_queue), | |
|
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|
6115 _mark_and_push(collector, span, bit_map, work_queue), |
| 0 | 6116 _low_water_mark(MIN2((uint)(work_queue->max_elems()/4), |
| 6117 (uint)(CMSWorkQueueDrainThreshold * ParallelGCThreads))) | |
| 6118 { } | |
| 6119 | |
| 6120 // . see if we can share work_queues with ParNew? XXX | |
| 6121 void CMSRefProcTaskProxy::do_work_steal(int i, | |
| 6122 CMSParDrainMarkingStackClosure* drain, | |
| 6123 CMSParKeepAliveClosure* keep_alive, | |
| 6124 int* seed) { | |
| 6125 OopTaskQueue* work_q = work_queue(i); | |
| 6126 NOT_PRODUCT(int num_steals = 0;) | |
| 6127 oop obj_to_scan; | |
| 6128 | |
| 6129 while (true) { | |
| 6130 // Completely finish any left over work from (an) earlier round(s) | |
| 6131 drain->trim_queue(0); | |
|
679
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6819891: ParNew: Fix work queue overflow code to deal correctly with +UseCompressedOops
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|
6132 size_t num_from_overflow_list = MIN2((size_t)(work_q->max_elems() - work_q->size())/4, |
|
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|
6133 (size_t)ParGCDesiredObjsFromOverflowList); |
| 0 | 6134 // Now check if there's any work in the overflow list |
|
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|
6135 // Passing ParallelGCThreads as the third parameter, no_of_gc_threads, |
|
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|
6136 // only affects the number of attempts made to get work from the |
|
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|
6137 // overflow list and does not affect the number of workers. Just |
|
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|
6138 // pass ParallelGCThreads so this behavior is unchanged. |
| 0 | 6139 if (_collector->par_take_from_overflow_list(num_from_overflow_list, |
|
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|
6140 work_q, |
|
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|
6141 ParallelGCThreads)) { |
| 0 | 6142 // Found something in global overflow list; |
| 6143 // not yet ready to go stealing work from others. | |
| 6144 // We'd like to assert(work_q->size() != 0, ...) | |
| 6145 // because we just took work from the overflow list, | |
| 6146 // but of course we can't, since all of that might have | |
| 6147 // been already stolen from us. | |
| 6148 continue; | |
| 6149 } | |
| 6150 // Verify that we have no work before we resort to stealing | |
| 6151 assert(work_q->size() == 0, "Have work, shouldn't steal"); | |
| 6152 // Try to steal from other queues that have work | |
| 6153 if (task_queues()->steal(i, seed, /* reference */ obj_to_scan)) { | |
| 6154 NOT_PRODUCT(num_steals++;) | |
| 6155 assert(obj_to_scan->is_oop(), "Oops, not an oop!"); | |
| 6156 assert(_mark_bit_map->isMarked((HeapWord*)obj_to_scan), "Stole an unmarked oop?"); | |
| 6157 // Do scanning work | |
| 6158 obj_to_scan->oop_iterate(keep_alive); | |
| 6159 // Loop around, finish this work, and try to steal some more | |
| 6160 } else if (terminator()->offer_termination()) { | |
| 6161 break; // nirvana from the infinite cycle | |
| 6162 } | |
| 6163 } | |
| 6164 NOT_PRODUCT( | |
| 6165 if (PrintCMSStatistics != 0) { | |
| 6166 gclog_or_tty->print("\n\t(%d: stole %d oops)", i, num_steals); | |
| 6167 } | |
| 6168 ) | |
| 6169 } | |
| 6170 | |
| 6171 void CMSRefProcTaskExecutor::execute(ProcessTask& task) | |
| 6172 { | |
| 6173 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
|
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|
6174 FlexibleWorkGang* workers = gch->workers(); |
| 0 | 6175 assert(workers != NULL, "Need parallel worker threads."); |
| 6176 CMSRefProcTaskProxy rp_task(task, &_collector, | |
| 6177 _collector.ref_processor()->span(), | |
| 6178 _collector.markBitMap(), | |
|
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|
6179 workers, _collector.task_queues()); |
| 0 | 6180 workers->run_task(&rp_task); |
| 6181 } | |
| 6182 | |
| 6183 void CMSRefProcTaskExecutor::execute(EnqueueTask& task) | |
| 6184 { | |
| 6185 | |
| 6186 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
|
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|
6187 FlexibleWorkGang* workers = gch->workers(); |
| 0 | 6188 assert(workers != NULL, "Need parallel worker threads."); |
| 6189 CMSRefEnqueueTaskProxy enq_task(task); | |
| 6190 workers->run_task(&enq_task); | |
| 6191 } | |
| 6192 | |
| 6193 void CMSCollector::refProcessingWork(bool asynch, bool clear_all_soft_refs) { | |
| 6194 | |
| 6195 ResourceMark rm; | |
| 6196 HandleMark hm; | |
| 6197 | |
| 6198 ReferenceProcessor* rp = ref_processor(); | |
| 6199 assert(rp->span().equals(_span), "Spans should be equal"); | |
|
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|
6200 assert(!rp->enqueuing_is_done(), "Enqueuing should not be complete"); |
|
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|
6201 // Process weak references. |
|
457
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diff
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|
6202 rp->setup_policy(clear_all_soft_refs); |
|
453
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|
6203 verify_work_stacks_empty(); |
|
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|
6204 |
| 0 | 6205 CMSKeepAliveClosure cmsKeepAliveClosure(this, _span, &_markBitMap, |
|
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|
6206 &_markStack, false /* !preclean */); |
| 0 | 6207 CMSDrainMarkingStackClosure cmsDrainMarkingStackClosure(this, |
| 6208 _span, &_markBitMap, &_markStack, | |
|
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|
6209 &cmsKeepAliveClosure, false /* !preclean */); |
| 0 | 6210 { |
| 10405 | 6211 GCTraceTime t("weak refs processing", PrintGCDetails, false, _gc_timer_cm); |
| 6212 | |
| 6213 ReferenceProcessorStats stats; | |
| 0 | 6214 if (rp->processing_is_mt()) { |
|
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|
6215 // Set the degree of MT here. If the discovery is done MT, there |
|
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|
6216 // may have been a different number of threads doing the discovery |
|
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|
6217 // and a different number of discovered lists may have Ref objects. |
|
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|
6218 // That is OK as long as the Reference lists are balanced (see |
|
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|
6219 // balance_all_queues() and balance_queues()). |
|
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|
6220 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
|
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|
6221 int active_workers = ParallelGCThreads; |
|
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|
6222 FlexibleWorkGang* workers = gch->workers(); |
|
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diff
changeset
|
6223 if (workers != NULL) { |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
parents:
3979
diff
changeset
|
6224 active_workers = workers->active_workers(); |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
parents:
3979
diff
changeset
|
6225 // The expectation is that active_workers will have already |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
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3979
diff
changeset
|
6226 // been set to a reasonable value. If it has not been set, |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
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3979
diff
changeset
|
6227 // investigate. |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
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3979
diff
changeset
|
6228 assert(active_workers > 0, "Should have been set during scavenge"); |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
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3979
diff
changeset
|
6229 } |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
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3979
diff
changeset
|
6230 rp->set_active_mt_degree(active_workers); |
| 0 | 6231 CMSRefProcTaskExecutor task_executor(*this); |
| 10405 | 6232 stats = rp->process_discovered_references(&_is_alive_closure, |
| 0 | 6233 &cmsKeepAliveClosure, |
| 6234 &cmsDrainMarkingStackClosure, | |
| 10405 | 6235 &task_executor, |
| 6236 _gc_timer_cm); | |
| 0 | 6237 } else { |
| 10405 | 6238 stats = rp->process_discovered_references(&_is_alive_closure, |
| 0 | 6239 &cmsKeepAliveClosure, |
| 6240 &cmsDrainMarkingStackClosure, | |
| 10405 | 6241 NULL, |
| 6242 _gc_timer_cm); | |
| 6243 } | |
| 6244 _gc_tracer_cm->report_gc_reference_stats(stats); | |
| 6245 | |
|
10188
2f50bc369470
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stefank
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10186
diff
changeset
|
6246 } |
|
2f50bc369470
8013160: NPG: Remove unnecessary mark stack draining after CodeCache::do_unloading
stefank
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10186
diff
changeset
|
6247 |
|
2f50bc369470
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stefank
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10186
diff
changeset
|
6248 // 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
|
6249 verify_work_stacks_empty(); |
| 0 | 6250 |
|
94
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
6251 if (should_unload_classes()) { |
| 0 | 6252 { |
| 10405 | 6253 GCTraceTime t("class unloading", PrintGCDetails, false, _gc_timer_cm); |
| 0 | 6254 |
|
10188
2f50bc369470
8013160: NPG: Remove unnecessary mark stack draining after CodeCache::do_unloading
stefank
parents:
10186
diff
changeset
|
6255 // Unload classes and purge the SystemDictionary. |
| 0 | 6256 bool purged_class = SystemDictionary::do_unloading(&_is_alive_closure); |
| 6257 | |
|
10188
2f50bc369470
8013160: NPG: Remove unnecessary mark stack draining after CodeCache::do_unloading
stefank
parents:
10186
diff
changeset
|
6258 // Unload nmethods. |
|
6787
8966c2d65d96
7200470: KeepAliveClosure not needed in CodeCache::do_unloading
brutisso
parents:
6755
diff
changeset
|
6259 CodeCache::do_unloading(&_is_alive_closure, purged_class); |
| 0 | 6260 |
|
10188
2f50bc369470
8013160: NPG: Remove unnecessary mark stack draining after CodeCache::do_unloading
stefank
parents:
10186
diff
changeset
|
6261 // 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
|
6262 Klass::clean_weak_klass_links(&_is_alive_closure); |
| 0 | 6263 } |
| 6264 | |
| 6265 { | |
| 10405 | 6266 GCTraceTime t("scrub symbol table", PrintGCDetails, false, _gc_timer_cm); |
|
2177
3582bf76420e
6990754: Use native memory and reference counting to implement SymbolTable
coleenp
parents:
2147
diff
changeset
|
6267 // Clean up unreferenced symbols in symbol table. |
|
3582bf76420e
6990754: Use native memory and reference counting to implement SymbolTable
coleenp
parents:
2147
diff
changeset
|
6268 SymbolTable::unlink(); |
| 0 | 6269 } |
| 6270 } | |
| 6271 | |
|
6725
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
6272 // CMS doesn't use the StringTable as hard roots when class unloading is turned off. |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
6273 // Need to check if we really scanned the StringTable. |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
6274 if ((roots_scanning_options() & SharedHeap::SO_Strings) == 0) { |
| 10405 | 6275 GCTraceTime t("scrub string table", PrintGCDetails, false, _gc_timer_cm); |
|
10188
2f50bc369470
8013160: NPG: Remove unnecessary mark stack draining after CodeCache::do_unloading
stefank
parents:
10186
diff
changeset
|
6276 // Delete entries for dead interned strings. |
|
2379
b099aaf51bf8
6962931: move interned strings out of the perm gen
jcoomes
parents:
2369
diff
changeset
|
6277 StringTable::unlink(&_is_alive_closure); |
|
b099aaf51bf8
6962931: move interned strings out of the perm gen
jcoomes
parents:
2369
diff
changeset
|
6278 } |
|
b099aaf51bf8
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jcoomes
parents:
2369
diff
changeset
|
6279 |
| 0 | 6280 // Restore any preserved marks as a result of mark stack or |
| 6281 // work queue overflow | |
| 6282 restore_preserved_marks_if_any(); // done single-threaded for now | |
| 6283 | |
| 6284 rp->set_enqueuing_is_done(true); | |
| 6285 if (rp->processing_is_mt()) { | |
|
1833
8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
jmasa
parents:
1777
diff
changeset
|
6286 rp->balance_all_queues(); |
| 0 | 6287 CMSRefProcTaskExecutor task_executor(*this); |
| 6288 rp->enqueue_discovered_references(&task_executor); | |
| 6289 } else { | |
| 6290 rp->enqueue_discovered_references(NULL); | |
| 6291 } | |
| 6292 rp->verify_no_references_recorded(); | |
| 6293 assert(!rp->discovery_enabled(), "should have been disabled"); | |
| 6294 } | |
| 6295 | |
| 6296 #ifndef PRODUCT | |
| 6297 void CMSCollector::check_correct_thread_executing() { | |
| 6298 Thread* t = Thread::current(); | |
| 6299 // Only the VM thread or the CMS thread should be here. | |
| 6300 assert(t->is_ConcurrentGC_thread() || t->is_VM_thread(), | |
| 6301 "Unexpected thread type"); | |
| 6302 // If this is the vm thread, the foreground process | |
| 6303 // should not be waiting. Note that _foregroundGCIsActive is | |
| 6304 // true while the foreground collector is waiting. | |
| 6305 if (_foregroundGCShouldWait) { | |
| 6306 // We cannot be the VM thread | |
| 6307 assert(t->is_ConcurrentGC_thread(), | |
| 6308 "Should be CMS thread"); | |
| 6309 } else { | |
| 6310 // We can be the CMS thread only if we are in a stop-world | |
| 6311 // phase of CMS collection. | |
| 6312 if (t->is_ConcurrentGC_thread()) { | |
| 6313 assert(_collectorState == InitialMarking || | |
| 6314 _collectorState == FinalMarking, | |
| 6315 "Should be a stop-world phase"); | |
| 6316 // The CMS thread should be holding the CMS_token. | |
| 6317 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 6318 "Potential interference with concurrently " | |
| 6319 "executing VM thread"); | |
| 6320 } | |
| 6321 } | |
| 6322 } | |
| 6323 #endif | |
| 6324 | |
| 6325 void CMSCollector::sweep(bool asynch) { | |
| 6326 assert(_collectorState == Sweeping, "just checking"); | |
| 6327 check_correct_thread_executing(); | |
| 6328 verify_work_stacks_empty(); | |
| 6329 verify_overflow_empty(); | |
|
1145
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
6330 increment_sweep_count(); |
|
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
parents:
3293
diff
changeset
|
6331 TraceCMSMemoryManagerStats tms(_collectorState,GenCollectedHeap::heap()->gc_cause()); |
|
1703
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
6332 |
|
1145
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
6333 _inter_sweep_timer.stop(); |
|
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
6334 _inter_sweep_estimate.sample(_inter_sweep_timer.seconds()); |
| 0 | 6335 size_policy()->avg_cms_free_at_sweep()->sample(_cmsGen->free()); |
| 6336 | |
|
1145
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
6337 assert(!_intra_sweep_timer.is_active(), "Should not be active"); |
|
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
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1085
diff
changeset
|
6338 _intra_sweep_timer.reset(); |
|
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
6339 _intra_sweep_timer.start(); |
| 0 | 6340 if (asynch) { |
| 6341 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
| 6342 CMSPhaseAccounting pa(this, "sweep", !PrintGCDetails); | |
|
6725
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
6343 // First sweep the old gen |
| 0 | 6344 { |
| 6345 CMSTokenSyncWithLocks ts(true, _cmsGen->freelistLock(), | |
| 6346 bitMapLock()); | |
| 6347 sweepWork(_cmsGen, asynch); | |
| 6348 } | |
| 6349 | |
| 6350 // Update Universe::_heap_*_at_gc figures. | |
| 6351 // We need all the free list locks to make the abstract state | |
| 6352 // transition from Sweeping to Resetting. See detailed note | |
| 6353 // further below. | |
| 6354 { | |
|
6725
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
6355 CMSTokenSyncWithLocks ts(true, _cmsGen->freelistLock()); |
| 0 | 6356 // Update heap occupancy information which is used as |
| 6357 // input to soft ref clearing policy at the next gc. | |
| 6358 Universe::update_heap_info_at_gc(); | |
| 6359 _collectorState = Resizing; | |
| 6360 } | |
| 6361 } else { | |
| 6362 // already have needed locks | |
| 6363 sweepWork(_cmsGen, asynch); | |
| 6364 // Update heap occupancy information which is used as | |
| 6365 // input to soft ref clearing policy at the next gc. | |
| 6366 Universe::update_heap_info_at_gc(); | |
| 6367 _collectorState = Resizing; | |
| 6368 } | |
| 6369 verify_work_stacks_empty(); | |
| 6370 verify_overflow_empty(); | |
| 6371 | |
|
8784
79af1312fc2c
8005602: NPG: classunloading does not happen while CMS GC with -XX:+CMSClassUnloadingEnabled is used
mgerdin
parents:
8740
diff
changeset
|
6372 if (should_unload_classes()) { |
|
17935
7384f6a12fc1
8038212: Method::is_valid_method() check has performance regression impact for stackwalking
coleenp
parents:
17771
diff
changeset
|
6373 // Delay purge to the beginning of the next safepoint. Metaspace::contains |
|
7384f6a12fc1
8038212: Method::is_valid_method() check has performance regression impact for stackwalking
coleenp
parents:
17771
diff
changeset
|
6374 // requires that the virtual spaces are stable and not deleted. |
|
7384f6a12fc1
8038212: Method::is_valid_method() check has performance regression impact for stackwalking
coleenp
parents:
17771
diff
changeset
|
6375 ClassLoaderDataGraph::set_should_purge(true); |
|
8784
79af1312fc2c
8005602: NPG: classunloading does not happen while CMS GC with -XX:+CMSClassUnloadingEnabled is used
mgerdin
parents:
8740
diff
changeset
|
6376 } |
|
79af1312fc2c
8005602: NPG: classunloading does not happen while CMS GC with -XX:+CMSClassUnloadingEnabled is used
mgerdin
parents:
8740
diff
changeset
|
6377 |
|
1145
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
6378 _intra_sweep_timer.stop(); |
|
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
6379 _intra_sweep_estimate.sample(_intra_sweep_timer.seconds()); |
|
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
6380 |
|
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
6381 _inter_sweep_timer.reset(); |
|
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
6382 _inter_sweep_timer.start(); |
| 0 | 6383 |
| 4911 | 6384 // We need to use a monotonically non-deccreasing time in ms |
| 6385 // or we will see time-warp warnings and os::javaTimeMillis() | |
| 6386 // does not guarantee monotonicity. | |
| 6387 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; | |
| 6388 update_time_of_last_gc(now); | |
| 0 | 6389 |
| 6390 // NOTE on abstract state transitions: | |
| 6391 // Mutators allocate-live and/or mark the mod-union table dirty | |
| 6392 // based on the state of the collection. The former is done in | |
| 6393 // the interval [Marking, Sweeping] and the latter in the interval | |
| 6394 // [Marking, Sweeping). Thus the transitions into the Marking state | |
| 6395 // and out of the Sweeping state must be synchronously visible | |
| 6396 // globally to the mutators. | |
| 6397 // The transition into the Marking state happens with the world | |
| 6398 // stopped so the mutators will globally see it. Sweeping is | |
| 6399 // done asynchronously by the background collector so the transition | |
| 6400 // from the Sweeping state to the Resizing state must be done | |
| 6401 // under the freelistLock (as is the check for whether to | |
| 6402 // allocate-live and whether to dirty the mod-union table). | |
| 6403 assert(_collectorState == Resizing, "Change of collector state to" | |
| 6404 " Resizing must be done under the freelistLocks (plural)"); | |
| 6405 | |
|
1888
a7214d79fcf1
6896603: CMS/GCH: collection_attempt_is_safe() ergo should use more recent data
ysr
parents:
1837
diff
changeset
|
6406 // Now that sweeping has been completed, we clear |
|
a7214d79fcf1
6896603: CMS/GCH: collection_attempt_is_safe() ergo should use more recent data
ysr
parents:
1837
diff
changeset
|
6407 // the incremental_collection_failed flag, |
| 0 | 6408 // thus inviting a younger gen collection to promote into |
| 6409 // this generation. If such a promotion may still fail, | |
| 6410 // the flag will be set again when a young collection is | |
| 6411 // attempted. | |
| 6412 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
|
1888
a7214d79fcf1
6896603: CMS/GCH: collection_attempt_is_safe() ergo should use more recent data
ysr
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1837
diff
changeset
|
6413 gch->clear_incremental_collection_failed(); // Worth retrying as fresh space may have been freed up |
| 0 | 6414 gch->update_full_collections_completed(_collection_count_start); |
| 6415 } | |
| 6416 | |
| 6417 // FIX ME!!! Looks like this belongs in CFLSpace, with | |
| 6418 // CMSGen merely delegating to it. | |
| 6419 void ConcurrentMarkSweepGeneration::setNearLargestChunk() { | |
|
1145
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6631166: CMS: better heuristics when combatting fragmentation
ysr
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1085
diff
changeset
|
6420 double nearLargestPercent = FLSLargestBlockCoalesceProximity; |
| 0 | 6421 HeapWord* minAddr = _cmsSpace->bottom(); |
| 6422 HeapWord* largestAddr = | |
|
6028
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
parents:
6026
diff
changeset
|
6423 (HeapWord*) _cmsSpace->dictionary()->find_largest_dict(); |
|
1145
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
6424 if (largestAddr == NULL) { |
| 0 | 6425 // The dictionary appears to be empty. In this case |
| 6426 // try to coalesce at the end of the heap. | |
| 6427 largestAddr = _cmsSpace->end(); | |
| 6428 } | |
| 6429 size_t largestOffset = pointer_delta(largestAddr, minAddr); | |
| 6430 size_t nearLargestOffset = | |
| 6431 (size_t)((double)largestOffset * nearLargestPercent) - MinChunkSize; | |
|
1145
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
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1085
diff
changeset
|
6432 if (PrintFLSStatistics != 0) { |
|
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
6433 gclog_or_tty->print_cr( |
|
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
6434 "CMS: Large Block: " PTR_FORMAT ";" |
|
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
6435 " Proximity: " PTR_FORMAT " -> " PTR_FORMAT, |
|
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
6436 largestAddr, |
|
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
6437 _cmsSpace->nearLargestChunk(), minAddr + nearLargestOffset); |
|
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
6438 } |
| 0 | 6439 _cmsSpace->set_nearLargestChunk(minAddr + nearLargestOffset); |
| 6440 } | |
| 6441 | |
| 6442 bool ConcurrentMarkSweepGeneration::isNearLargestChunk(HeapWord* addr) { | |
| 6443 return addr >= _cmsSpace->nearLargestChunk(); | |
| 6444 } | |
| 6445 | |
| 6446 FreeChunk* ConcurrentMarkSweepGeneration::find_chunk_at_end() { | |
| 6447 return _cmsSpace->find_chunk_at_end(); | |
| 6448 } | |
| 6449 | |
| 6450 void ConcurrentMarkSweepGeneration::update_gc_stats(int current_level, | |
| 6451 bool full) { | |
| 6452 // The next lower level has been collected. Gather any statistics | |
| 6453 // that are of interest at this point. | |
| 6454 if (!full && (current_level + 1) == level()) { | |
| 6455 // Gather statistics on the young generation collection. | |
| 6456 collector()->stats().record_gc0_end(used()); | |
| 6457 } | |
| 6458 } | |
| 6459 | |
| 6460 CMSAdaptiveSizePolicy* ConcurrentMarkSweepGeneration::size_policy() { | |
| 6461 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 6462 assert(gch->kind() == CollectedHeap::GenCollectedHeap, | |
| 6463 "Wrong type of heap"); | |
| 6464 CMSAdaptiveSizePolicy* sp = (CMSAdaptiveSizePolicy*) | |
| 6465 gch->gen_policy()->size_policy(); | |
| 6466 assert(sp->is_gc_cms_adaptive_size_policy(), | |
| 6467 "Wrong type of size policy"); | |
| 6468 return sp; | |
| 6469 } | |
| 6470 | |
| 6471 void ConcurrentMarkSweepGeneration::rotate_debug_collection_type() { | |
| 6472 if (PrintGCDetails && Verbose) { | |
| 6473 gclog_or_tty->print("Rotate from %d ", _debug_collection_type); | |
| 6474 } | |
| 6475 _debug_collection_type = (CollectionTypes) (_debug_collection_type + 1); | |
| 6476 _debug_collection_type = | |
| 6477 (CollectionTypes) (_debug_collection_type % Unknown_collection_type); | |
| 6478 if (PrintGCDetails && Verbose) { | |
| 6479 gclog_or_tty->print_cr("to %d ", _debug_collection_type); | |
| 6480 } | |
| 6481 } | |
| 6482 | |
| 6483 void CMSCollector::sweepWork(ConcurrentMarkSweepGeneration* gen, | |
| 6484 bool asynch) { | |
| 6485 // We iterate over the space(s) underlying this generation, | |
| 6486 // checking the mark bit map to see if the bits corresponding | |
| 6487 // to specific blocks are marked or not. Blocks that are | |
| 6488 // marked are live and are not swept up. All remaining blocks | |
| 6489 // are swept up, with coalescing on-the-fly as we sweep up | |
| 6490 // contiguous free and/or garbage blocks: | |
| 6491 // We need to ensure that the sweeper synchronizes with allocators | |
| 6492 // and stop-the-world collectors. In particular, the following | |
| 6493 // locks are used: | |
| 6494 // . CMS token: if this is held, a stop the world collection cannot occur | |
| 6495 // . freelistLock: if this is held no allocation can occur from this | |
| 6496 // generation by another thread | |
| 6497 // . bitMapLock: if this is held, no other thread can access or update | |
| 6498 // | |
| 6499 | |
| 6500 // Note that we need to hold the freelistLock if we use | |
| 6501 // block iterate below; else the iterator might go awry if | |
| 6502 // a mutator (or promotion) causes block contents to change | |
| 6503 // (for instance if the allocator divvies up a block). | |
| 6504 // If we hold the free list lock, for all practical purposes | |
| 6505 // young generation GC's can't occur (they'll usually need to | |
| 6506 // promote), so we might as well prevent all young generation | |
| 6507 // GC's while we do a sweeping step. For the same reason, we might | |
| 6508 // as well take the bit map lock for the entire duration | |
| 6509 | |
| 6510 // check that we hold the requisite locks | |
| 6511 assert(have_cms_token(), "Should hold cms token"); | |
| 6512 assert( (asynch && ConcurrentMarkSweepThread::cms_thread_has_cms_token()) | |
| 6513 || (!asynch && ConcurrentMarkSweepThread::vm_thread_has_cms_token()), | |
| 6514 "Should possess CMS token to sweep"); | |
| 6515 assert_lock_strong(gen->freelistLock()); | |
| 6516 assert_lock_strong(bitMapLock()); | |
| 6517 | |
|
1145
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
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1085
diff
changeset
|
6518 assert(!_inter_sweep_timer.is_active(), "Was switched off in an outer context"); |
|
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
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parents:
1085
diff
changeset
|
6519 assert(_intra_sweep_timer.is_active(), "Was switched on in an outer context"); |
|
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
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parents:
1085
diff
changeset
|
6520 gen->cmsSpace()->beginSweepFLCensus((float)(_inter_sweep_timer.seconds()), |
|
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
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parents:
1085
diff
changeset
|
6521 _inter_sweep_estimate.padded_average(), |
|
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
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parents:
1085
diff
changeset
|
6522 _intra_sweep_estimate.padded_average()); |
| 0 | 6523 gen->setNearLargestChunk(); |
| 6524 | |
| 6525 { | |
| 6526 SweepClosure sweepClosure(this, gen, &_markBitMap, | |
| 6527 CMSYield && asynch); | |
| 6528 gen->cmsSpace()->blk_iterate_careful(&sweepClosure); | |
| 6529 // We need to free-up/coalesce garbage/blocks from a | |
| 6530 // co-terminal free run. This is done in the SweepClosure | |
| 6531 // destructor; so, do not remove this scope, else the | |
| 6532 // end-of-sweep-census below will be off by a little bit. | |
| 6533 } | |
| 6534 gen->cmsSpace()->sweep_completed(); | |
|
1145
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6631166: CMS: better heuristics when combatting fragmentation
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parents:
1085
diff
changeset
|
6535 gen->cmsSpace()->endSweepFLCensus(sweep_count()); |
|
94
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
6536 if (should_unload_classes()) { // unloaded classes this cycle, |
|
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
6537 _concurrent_cycles_since_last_unload = 0; // ... reset count |
|
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
6538 } else { // did not unload classes, |
|
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
6539 _concurrent_cycles_since_last_unload++; // ... increment count |
|
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
6540 } |
| 0 | 6541 } |
| 6542 | |
| 6543 // Reset CMS data structures (for now just the marking bit map) | |
| 6544 // preparatory for the next cycle. | |
| 6545 void CMSCollector::reset(bool asynch) { | |
| 6546 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 6547 CMSAdaptiveSizePolicy* sp = size_policy(); | |
| 6548 AdaptiveSizePolicyOutput(sp, gch->total_collections()); | |
| 6549 if (asynch) { | |
| 6550 CMSTokenSyncWithLocks ts(true, bitMapLock()); | |
| 6551 | |
| 6552 // If the state is not "Resetting", the foreground thread | |
| 6553 // has done a collection and the resetting. | |
| 6554 if (_collectorState != Resetting) { | |
| 6555 assert(_collectorState == Idling, "The state should only change" | |
| 6556 " because the foreground collector has finished the collection"); | |
| 6557 return; | |
| 6558 } | |
| 6559 | |
| 6560 // Clear the mark bitmap (no grey objects to start with) | |
| 6561 // for the next cycle. | |
| 6562 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
| 6563 CMSPhaseAccounting cmspa(this, "reset", !PrintGCDetails); | |
| 6564 | |
| 6565 HeapWord* curAddr = _markBitMap.startWord(); | |
| 6566 while (curAddr < _markBitMap.endWord()) { | |
| 6567 size_t remaining = pointer_delta(_markBitMap.endWord(), curAddr); | |
| 6568 MemRegion chunk(curAddr, MIN2(CMSBitMapYieldQuantum, remaining)); | |
| 6569 _markBitMap.clear_large_range(chunk); | |
| 6570 if (ConcurrentMarkSweepThread::should_yield() && | |
| 6571 !foregroundGCIsActive() && | |
| 6572 CMSYield) { | |
| 6573 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 6574 "CMS thread should hold CMS token"); | |
| 6575 assert_lock_strong(bitMapLock()); | |
| 6576 bitMapLock()->unlock(); | |
| 6577 ConcurrentMarkSweepThread::desynchronize(true); | |
| 6578 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 6579 stopTimer(); | |
| 6580 if (PrintCMSStatistics != 0) { | |
| 6581 incrementYields(); | |
| 6582 } | |
| 6583 icms_wait(); | |
| 6584 | |
| 6585 // See the comment in coordinator_yield() | |
| 6586 for (unsigned i = 0; i < CMSYieldSleepCount && | |
|
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6587 ConcurrentMarkSweepThread::should_yield() && |
|
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6588 !CMSCollector::foregroundGCIsActive(); ++i) { |
| 0 | 6589 os::sleep(Thread::current(), 1, false); |
| 6590 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 6591 } | |
| 6592 | |
| 6593 ConcurrentMarkSweepThread::synchronize(true); | |
| 6594 bitMapLock()->lock_without_safepoint_check(); | |
| 6595 startTimer(); | |
| 6596 } | |
| 6597 curAddr = chunk.end(); | |
| 6598 } | |
|
1387
0bfd3fb24150
6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
jmasa
parents:
1289
diff
changeset
|
6599 // A successful mostly concurrent collection has been done. |
|
0bfd3fb24150
6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
jmasa
parents:
1289
diff
changeset
|
6600 // Because only the full (i.e., concurrent mode failure) collections |
|
0bfd3fb24150
6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
jmasa
parents:
1289
diff
changeset
|
6601 // are being measured for gc overhead limits, clean the "near" flag |
|
0bfd3fb24150
6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
jmasa
parents:
1289
diff
changeset
|
6602 // and count. |
|
0bfd3fb24150
6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
jmasa
parents:
1289
diff
changeset
|
6603 sp->reset_gc_overhead_limit_count(); |
| 0 | 6604 _collectorState = Idling; |
| 6605 } else { | |
| 6606 // already have the lock | |
| 6607 assert(_collectorState == Resetting, "just checking"); | |
| 6608 assert_lock_strong(bitMapLock()); | |
| 6609 _markBitMap.clear_all(); | |
| 6610 _collectorState = Idling; | |
| 6611 } | |
| 6612 | |
| 6613 // Stop incremental mode after a cycle completes, so that any future cycles | |
| 6614 // are triggered by allocation. | |
| 6615 stop_icms(); | |
| 6616 | |
| 6617 NOT_PRODUCT( | |
| 6618 if (RotateCMSCollectionTypes) { | |
| 6619 _cmsGen->rotate_debug_collection_type(); | |
| 6620 } | |
| 6621 ) | |
| 10405 | 6622 |
| 6623 register_gc_end(); | |
| 0 | 6624 } |
| 6625 | |
|
6064
9d679effd28c
7166894: Add gc cause to GC logging for all collectors
brutisso
parents:
6028
diff
changeset
|
6626 void CMSCollector::do_CMS_operation(CMS_op_type op, GCCause::Cause gc_cause) { |
| 0 | 6627 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps); |
| 6628 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
| 10405 | 6629 GCTraceTime t(GCCauseString("GC", gc_cause), PrintGC, !PrintGCDetails, NULL); |
| 0 | 6630 TraceCollectorStats tcs(counters()); |
| 6631 | |
| 6632 switch (op) { | |
| 6633 case CMS_op_checkpointRootsInitial: { | |
|
2125
7246a374a9f2
6458402: 3 jvmti tests fail with CMS and +ExplicitGCInvokesConcurrent
kamg
parents:
1994
diff
changeset
|
6634 SvcGCMarker sgcm(SvcGCMarker::OTHER); |
| 0 | 6635 checkpointRootsInitial(true); // asynch |
| 6636 if (PrintGC) { | |
| 6637 _cmsGen->printOccupancy("initial-mark"); | |
| 6638 } | |
| 6639 break; | |
| 6640 } | |
| 6641 case CMS_op_checkpointRootsFinal: { | |
|
2125
7246a374a9f2
6458402: 3 jvmti tests fail with CMS and +ExplicitGCInvokesConcurrent
kamg
parents:
1994
diff
changeset
|
6642 SvcGCMarker sgcm(SvcGCMarker::OTHER); |
| 0 | 6643 checkpointRootsFinal(true, // asynch |
| 6644 false, // !clear_all_soft_refs | |
| 6645 false); // !init_mark_was_synchronous | |
| 6646 if (PrintGC) { | |
| 6647 _cmsGen->printOccupancy("remark"); | |
| 6648 } | |
| 6649 break; | |
| 6650 } | |
| 6651 default: | |
| 6652 fatal("No such CMS_op"); | |
| 6653 } | |
| 6654 } | |
| 6655 | |
| 6656 #ifndef PRODUCT | |
| 6657 size_t const CMSCollector::skip_header_HeapWords() { | |
| 6658 return FreeChunk::header_size(); | |
| 6659 } | |
| 6660 | |
| 6661 // Try and collect here conditions that should hold when | |
| 6662 // CMS thread is exiting. The idea is that the foreground GC | |
| 6663 // thread should not be blocked if it wants to terminate | |
| 6664 // the CMS thread and yet continue to run the VM for a while | |
| 6665 // after that. | |
| 6666 void CMSCollector::verify_ok_to_terminate() const { | |
| 6667 assert(Thread::current()->is_ConcurrentGC_thread(), | |
| 6668 "should be called by CMS thread"); | |
| 6669 assert(!_foregroundGCShouldWait, "should be false"); | |
| 6670 // We could check here that all the various low-level locks | |
| 6671 // are not held by the CMS thread, but that is overkill; see | |
| 6672 // also CMSThread::verify_ok_to_terminate() where the CGC_lock | |
| 6673 // is checked. | |
| 6674 } | |
| 6675 #endif | |
| 6676 | |
| 6677 size_t CMSCollector::block_size_using_printezis_bits(HeapWord* addr) const { | |
|
453
c96030fff130
6684579: SoftReference processing can be made more efficient
ysr
parents:
452
diff
changeset
|
6678 assert(_markBitMap.isMarked(addr) && _markBitMap.isMarked(addr + 1), |
|
c96030fff130
6684579: SoftReference processing can be made more efficient
ysr
parents:
452
diff
changeset
|
6679 "missing Printezis mark?"); |
| 0 | 6680 HeapWord* nextOneAddr = _markBitMap.getNextMarkedWordAddress(addr + 2); |
| 6681 size_t size = pointer_delta(nextOneAddr + 1, addr); | |
| 6682 assert(size == CompactibleFreeListSpace::adjustObjectSize(size), | |
| 6683 "alignment problem"); | |
| 6684 assert(size >= 3, "Necessary for Printezis marks to work"); | |
| 6685 return size; | |
| 6686 } | |
| 6687 | |
| 6688 // A variant of the above (block_size_using_printezis_bits()) except | |
| 6689 // that we return 0 if the P-bits are not yet set. | |
| 6690 size_t CMSCollector::block_size_if_printezis_bits(HeapWord* addr) const { | |
|
2226
c5a923563727
6912621: iCMS: Error: assert(_markBitMap.isMarked(addr + 1),"Missing Printezis bit?")
ysr
parents:
2177
diff
changeset
|
6691 if (_markBitMap.isMarked(addr + 1)) { |
|
c5a923563727
6912621: iCMS: Error: assert(_markBitMap.isMarked(addr + 1),"Missing Printezis bit?")
ysr
parents:
2177
diff
changeset
|
6692 assert(_markBitMap.isMarked(addr), "P-bit can be set only for marked objects"); |
| 0 | 6693 HeapWord* nextOneAddr = _markBitMap.getNextMarkedWordAddress(addr + 2); |
| 6694 size_t size = pointer_delta(nextOneAddr + 1, addr); | |
| 6695 assert(size == CompactibleFreeListSpace::adjustObjectSize(size), | |
| 6696 "alignment problem"); | |
| 6697 assert(size >= 3, "Necessary for Printezis marks to work"); | |
| 6698 return size; | |
|
2226
c5a923563727
6912621: iCMS: Error: assert(_markBitMap.isMarked(addr + 1),"Missing Printezis bit?")
ysr
parents:
2177
diff
changeset
|
6699 } |
|
c5a923563727
6912621: iCMS: Error: assert(_markBitMap.isMarked(addr + 1),"Missing Printezis bit?")
ysr
parents:
2177
diff
changeset
|
6700 return 0; |
| 0 | 6701 } |
| 6702 | |
| 6703 HeapWord* CMSCollector::next_card_start_after_block(HeapWord* addr) const { | |
| 6704 size_t sz = 0; | |
| 6705 oop p = (oop)addr; | |
|
6725
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
6706 if (p->klass_or_null() != NULL) { |
| 0 | 6707 sz = CompactibleFreeListSpace::adjustObjectSize(p->size()); |
| 6708 } else { | |
| 6709 sz = block_size_using_printezis_bits(addr); | |
| 6710 } | |
| 6711 assert(sz > 0, "size must be nonzero"); | |
| 6712 HeapWord* next_block = addr + sz; | |
| 6713 HeapWord* next_card = (HeapWord*)round_to((uintptr_t)next_block, | |
| 6714 CardTableModRefBS::card_size); | |
| 6715 assert(round_down((uintptr_t)addr, CardTableModRefBS::card_size) < | |
| 6716 round_down((uintptr_t)next_card, CardTableModRefBS::card_size), | |
| 6717 "must be different cards"); | |
| 6718 return next_card; | |
| 6719 } | |
| 6720 | |
| 6721 | |
| 6722 // CMS Bit Map Wrapper ///////////////////////////////////////// | |
| 6723 | |
| 6724 // Construct a CMS bit map infrastructure, but don't create the | |
| 6725 // bit vector itself. That is done by a separate call CMSBitMap::allocate() | |
| 6726 // further below. | |
| 6727 CMSBitMap::CMSBitMap(int shifter, int mutex_rank, const char* mutex_name): | |
|
342
37f87013dfd8
6711316: Open source the Garbage-First garbage collector
ysr
parents:
143
diff
changeset
|
6728 _bm(), |
| 0 | 6729 _shifter(shifter), |
| 6730 _lock(mutex_rank >= 0 ? new Mutex(mutex_rank, mutex_name, true) : NULL) | |
| 6731 { | |
| 6732 _bmStartWord = 0; | |
| 6733 _bmWordSize = 0; | |
| 6734 } | |
| 6735 | |
| 6736 bool CMSBitMap::allocate(MemRegion mr) { | |
| 6737 _bmStartWord = mr.start(); | |
| 6738 _bmWordSize = mr.word_size(); | |
| 6739 ReservedSpace brs(ReservedSpace::allocation_align_size_up( | |
| 6740 (_bmWordSize >> (_shifter + LogBitsPerByte)) + 1)); | |
| 6741 if (!brs.is_reserved()) { | |
| 6742 warning("CMS bit map allocation failure"); | |
| 6743 return false; | |
| 6744 } | |
| 6745 // For now we'll just commit all of the bit map up fromt. | |
| 6746 // Later on we'll try to be more parsimonious with swap. | |
| 6747 if (!_virtual_space.initialize(brs, brs.size())) { | |
| 6748 warning("CMS bit map backing store failure"); | |
| 6749 return false; | |
| 6750 } | |
| 6751 assert(_virtual_space.committed_size() == brs.size(), | |
| 6752 "didn't reserve backing store for all of CMS bit map?"); | |
|
342
37f87013dfd8
6711316: Open source the Garbage-First garbage collector
ysr
parents:
143
diff
changeset
|
6753 _bm.set_map((BitMap::bm_word_t*)_virtual_space.low()); |
| 0 | 6754 assert(_virtual_space.committed_size() << (_shifter + LogBitsPerByte) >= |
| 6755 _bmWordSize, "inconsistency in bit map sizing"); | |
| 6756 _bm.set_size(_bmWordSize >> _shifter); | |
| 6757 | |
| 6758 // bm.clear(); // can we rely on getting zero'd memory? verify below | |
| 6759 assert(isAllClear(), | |
| 6760 "Expected zero'd memory from ReservedSpace constructor"); | |
| 6761 assert(_bm.size() == heapWordDiffToOffsetDiff(sizeInWords()), | |
| 6762 "consistency check"); | |
| 6763 return true; | |
| 6764 } | |
| 6765 | |
| 6766 void CMSBitMap::dirty_range_iterate_clear(MemRegion mr, MemRegionClosure* cl) { | |
| 6767 HeapWord *next_addr, *end_addr, *last_addr; | |
| 6768 assert_locked(); | |
| 6769 assert(covers(mr), "out-of-range error"); | |
| 6770 // XXX assert that start and end are appropriately aligned | |
| 6771 for (next_addr = mr.start(), end_addr = mr.end(); | |
| 6772 next_addr < end_addr; next_addr = last_addr) { | |
| 6773 MemRegion dirty_region = getAndClearMarkedRegion(next_addr, end_addr); | |
| 6774 last_addr = dirty_region.end(); | |
| 6775 if (!dirty_region.is_empty()) { | |
| 6776 cl->do_MemRegion(dirty_region); | |
| 6777 } else { | |
| 6778 assert(last_addr == end_addr, "program logic"); | |
| 6779 return; | |
| 6780 } | |
| 6781 } | |
| 6782 } | |
| 6783 | |
|
9076
7b835924c31c
8011872: Include Bit Map addresses in the hs_err files
stefank
parents:
9072
diff
changeset
|
6784 void CMSBitMap::print_on_error(outputStream* st, const char* prefix) const { |
|
7b835924c31c
8011872: Include Bit Map addresses in the hs_err files
stefank
parents:
9072
diff
changeset
|
6785 _bm.print_on_error(st, prefix); |
|
7b835924c31c
8011872: Include Bit Map addresses in the hs_err files
stefank
parents:
9072
diff
changeset
|
6786 } |
|
7b835924c31c
8011872: Include Bit Map addresses in the hs_err files
stefank
parents:
9072
diff
changeset
|
6787 |
| 0 | 6788 #ifndef PRODUCT |
| 6789 void CMSBitMap::assert_locked() const { | |
| 6790 CMSLockVerifier::assert_locked(lock()); | |
| 6791 } | |
| 6792 | |
| 6793 bool CMSBitMap::covers(MemRegion mr) const { | |
| 6794 // assert(_bm.map() == _virtual_space.low(), "map inconsistency"); | |
| 6795 assert((size_t)_bm.size() == (_bmWordSize >> _shifter), | |
| 6796 "size inconsistency"); | |
| 6797 return (mr.start() >= _bmStartWord) && | |
| 6798 (mr.end() <= endWord()); | |
| 6799 } | |
| 6800 | |
| 6801 bool CMSBitMap::covers(HeapWord* start, size_t size) const { | |
| 6802 return (start >= _bmStartWord && (start + size) <= endWord()); | |
| 6803 } | |
| 6804 | |
| 6805 void CMSBitMap::verifyNoOneBitsInRange(HeapWord* left, HeapWord* right) { | |
| 6806 // verify that there are no 1 bits in the interval [left, right) | |
| 6807 FalseBitMapClosure falseBitMapClosure; | |
| 6808 iterate(&falseBitMapClosure, left, right); | |
| 6809 } | |
| 6810 | |
| 6811 void CMSBitMap::region_invariant(MemRegion mr) | |
| 6812 { | |
| 6813 assert_locked(); | |
| 6814 // mr = mr.intersection(MemRegion(_bmStartWord, _bmWordSize)); | |
| 6815 assert(!mr.is_empty(), "unexpected empty region"); | |
| 6816 assert(covers(mr), "mr should be covered by bit map"); | |
| 6817 // convert address range into offset range | |
| 6818 size_t start_ofs = heapWordToOffset(mr.start()); | |
| 6819 // Make sure that end() is appropriately aligned | |
| 6820 assert(mr.end() == (HeapWord*)round_to((intptr_t)mr.end(), | |
| 6821 (1 << (_shifter+LogHeapWordSize))), | |
| 6822 "Misaligned mr.end()"); | |
| 6823 size_t end_ofs = heapWordToOffset(mr.end()); | |
| 6824 assert(end_ofs > start_ofs, "Should mark at least one bit"); | |
| 6825 } | |
| 6826 | |
| 6827 #endif | |
| 6828 | |
| 6829 bool CMSMarkStack::allocate(size_t size) { | |
| 6830 // allocate a stack of the requisite depth | |
| 6831 ReservedSpace rs(ReservedSpace::allocation_align_size_up( | |
| 6832 size * sizeof(oop))); | |
| 6833 if (!rs.is_reserved()) { | |
| 6834 warning("CMSMarkStack allocation failure"); | |
| 6835 return false; | |
| 6836 } | |
| 6837 if (!_virtual_space.initialize(rs, rs.size())) { | |
| 6838 warning("CMSMarkStack backing store failure"); | |
| 6839 return false; | |
| 6840 } | |
| 6841 assert(_virtual_space.committed_size() == rs.size(), | |
| 6842 "didn't reserve backing store for all of CMS stack?"); | |
| 6843 _base = (oop*)(_virtual_space.low()); | |
| 6844 _index = 0; | |
| 6845 _capacity = size; | |
| 6846 NOT_PRODUCT(_max_depth = 0); | |
| 6847 return true; | |
| 6848 } | |
| 6849 | |
| 6850 // XXX FIX ME !!! In the MT case we come in here holding a | |
| 6851 // leaf lock. For printing we need to take a further lock | |
| 6852 // which has lower rank. We need to recallibrate the two | |
| 6853 // lock-ranks involved in order to be able to rpint the | |
| 6854 // messages below. (Or defer the printing to the caller. | |
| 6855 // For now we take the expedient path of just disabling the | |
| 6856 // messages for the problematic case.) | |
| 6857 void CMSMarkStack::expand() { | |
| 1284 | 6858 assert(_capacity <= MarkStackSizeMax, "stack bigger than permitted"); |
| 6859 if (_capacity == MarkStackSizeMax) { | |
| 0 | 6860 if (_hit_limit++ == 0 && !CMSConcurrentMTEnabled && PrintGCDetails) { |
| 6861 // We print a warning message only once per CMS cycle. | |
| 6862 gclog_or_tty->print_cr(" (benign) Hit CMSMarkStack max size limit"); | |
| 6863 } | |
| 6864 return; | |
| 6865 } | |
| 6866 // Double capacity if possible | |
| 1284 | 6867 size_t new_capacity = MIN2(_capacity*2, MarkStackSizeMax); |
| 0 | 6868 // Do not give up existing stack until we have managed to |
| 6869 // get the double capacity that we desired. | |
| 6870 ReservedSpace rs(ReservedSpace::allocation_align_size_up( | |
| 6871 new_capacity * sizeof(oop))); | |
| 6872 if (rs.is_reserved()) { | |
| 6873 // Release the backing store associated with old stack | |
| 6874 _virtual_space.release(); | |
| 6875 // Reinitialize virtual space for new stack | |
| 6876 if (!_virtual_space.initialize(rs, rs.size())) { | |
| 6877 fatal("Not enough swap for expanded marking stack"); | |
| 6878 } | |
| 6879 _base = (oop*)(_virtual_space.low()); | |
| 6880 _index = 0; | |
| 6881 _capacity = new_capacity; | |
| 6882 } else if (_failed_double++ == 0 && !CMSConcurrentMTEnabled && PrintGCDetails) { | |
| 6883 // Failed to double capacity, continue; | |
| 6884 // we print a detail message only once per CMS cycle. | |
| 6885 gclog_or_tty->print(" (benign) Failed to expand marking stack from "SIZE_FORMAT"K to " | |
| 6886 SIZE_FORMAT"K", | |
| 6887 _capacity / K, new_capacity / K); | |
| 6888 } | |
| 6889 } | |
| 6890 | |
| 6891 | |
| 6892 // Closures | |
| 6893 // XXX: there seems to be a lot of code duplication here; | |
| 6894 // should refactor and consolidate common code. | |
| 6895 | |
| 6896 // This closure is used to mark refs into the CMS generation in | |
| 6897 // the CMS bit map. Called at the first checkpoint. This closure | |
| 6898 // assumes that we do not need to re-mark dirty cards; if the CMS | |
|
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6899 // generation on which this is used is not an oldest |
| 0 | 6900 // generation then this will lose younger_gen cards! |
| 6901 | |
| 6902 MarkRefsIntoClosure::MarkRefsIntoClosure( | |
|
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6903 MemRegion span, CMSBitMap* bitMap): |
| 0 | 6904 _span(span), |
|
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6905 _bitMap(bitMap) |
| 0 | 6906 { |
| 6907 assert(_ref_processor == NULL, "deliberately left NULL"); | |
| 6908 assert(_bitMap->covers(_span), "_bitMap/_span mismatch"); | |
| 6909 } | |
| 6910 | |
|
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6911 void MarkRefsIntoClosure::do_oop(oop obj) { |
| 0 | 6912 // if p points into _span, then mark corresponding bit in _markBitMap |
|
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6913 assert(obj->is_oop(), "expected an oop"); |
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6914 HeapWord* addr = (HeapWord*)obj; |
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6915 if (_span.contains(addr)) { |
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6916 // this should be made more efficient |
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6917 _bitMap->mark(addr); |
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6918 } |
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6919 } |
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6920 |
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6921 void MarkRefsIntoClosure::do_oop(oop* p) { MarkRefsIntoClosure::do_oop_work(p); } |
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6922 void MarkRefsIntoClosure::do_oop(narrowOop* p) { MarkRefsIntoClosure::do_oop_work(p); } |
| 0 | 6923 |
| 11975 | 6924 Par_MarkRefsIntoClosure::Par_MarkRefsIntoClosure( |
| 6925 MemRegion span, CMSBitMap* bitMap): | |
| 6926 _span(span), | |
| 6927 _bitMap(bitMap) | |
| 6928 { | |
| 6929 assert(_ref_processor == NULL, "deliberately left NULL"); | |
| 6930 assert(_bitMap->covers(_span), "_bitMap/_span mismatch"); | |
| 6931 } | |
| 6932 | |
| 6933 void Par_MarkRefsIntoClosure::do_oop(oop obj) { | |
| 6934 // if p points into _span, then mark corresponding bit in _markBitMap | |
| 6935 assert(obj->is_oop(), "expected an oop"); | |
| 6936 HeapWord* addr = (HeapWord*)obj; | |
| 6937 if (_span.contains(addr)) { | |
| 6938 // this should be made more efficient | |
| 6939 _bitMap->par_mark(addr); | |
| 6940 } | |
| 6941 } | |
| 6942 | |
| 6943 void Par_MarkRefsIntoClosure::do_oop(oop* p) { Par_MarkRefsIntoClosure::do_oop_work(p); } | |
| 6944 void Par_MarkRefsIntoClosure::do_oop(narrowOop* p) { Par_MarkRefsIntoClosure::do_oop_work(p); } | |
| 6945 | |
| 0 | 6946 // A variant of the above, used for CMS marking verification. |
| 6947 MarkRefsIntoVerifyClosure::MarkRefsIntoVerifyClosure( | |
|
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6948 MemRegion span, CMSBitMap* verification_bm, CMSBitMap* cms_bm): |
| 0 | 6949 _span(span), |
| 6950 _verification_bm(verification_bm), | |
|
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6951 _cms_bm(cms_bm) |
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6952 { |
| 0 | 6953 assert(_ref_processor == NULL, "deliberately left NULL"); |
| 6954 assert(_verification_bm->covers(_span), "_verification_bm/_span mismatch"); | |
| 6955 } | |
| 6956 | |
|
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6957 void MarkRefsIntoVerifyClosure::do_oop(oop obj) { |
| 0 | 6958 // if p points into _span, then mark corresponding bit in _markBitMap |
|
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6959 assert(obj->is_oop(), "expected an oop"); |
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6960 HeapWord* addr = (HeapWord*)obj; |
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6961 if (_span.contains(addr)) { |
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6962 _verification_bm->mark(addr); |
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6963 if (!_cms_bm->isMarked(addr)) { |
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6964 oop(addr)->print(); |
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6965 gclog_or_tty->print_cr(" (" INTPTR_FORMAT " should have been marked)", addr); |
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6966 fatal("... aborting"); |
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6967 } |
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6968 } |
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6969 } |
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6970 |
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6971 void MarkRefsIntoVerifyClosure::do_oop(oop* p) { MarkRefsIntoVerifyClosure::do_oop_work(p); } |
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6972 void MarkRefsIntoVerifyClosure::do_oop(narrowOop* p) { MarkRefsIntoVerifyClosure::do_oop_work(p); } |
| 0 | 6973 |
| 6974 ////////////////////////////////////////////////// | |
| 6975 // MarkRefsIntoAndScanClosure | |
| 6976 ////////////////////////////////////////////////// | |
| 6977 | |
| 6978 MarkRefsIntoAndScanClosure::MarkRefsIntoAndScanClosure(MemRegion span, | |
| 6979 ReferenceProcessor* rp, | |
| 6980 CMSBitMap* bit_map, | |
| 6981 CMSBitMap* mod_union_table, | |
| 6982 CMSMarkStack* mark_stack, | |
| 6983 CMSCollector* collector, | |
| 6984 bool should_yield, | |
| 6985 bool concurrent_precleaning): | |
| 6986 _collector(collector), | |
| 6987 _span(span), | |
| 6988 _bit_map(bit_map), | |
| 6989 _mark_stack(mark_stack), | |
| 6990 _pushAndMarkClosure(collector, span, rp, bit_map, mod_union_table, | |
|
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6991 mark_stack, concurrent_precleaning), |
| 0 | 6992 _yield(should_yield), |
| 6993 _concurrent_precleaning(concurrent_precleaning), | |
| 6994 _freelistLock(NULL) | |
| 6995 { | |
| 6996 _ref_processor = rp; | |
| 6997 assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL"); | |
| 6998 } | |
| 6999 | |
| 7000 // This closure is used to mark refs into the CMS generation at the | |
| 7001 // second (final) checkpoint, and to scan and transitively follow | |
| 7002 // the unmarked oops. It is also used during the concurrent precleaning | |
| 7003 // phase while scanning objects on dirty cards in the CMS generation. | |
| 7004 // The marks are made in the marking bit map and the marking stack is | |
| 7005 // used for keeping the (newly) grey objects during the scan. | |
| 7006 // The parallel version (Par_...) appears further below. | |
|
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7007 void MarkRefsIntoAndScanClosure::do_oop(oop obj) { |
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7008 if (obj != NULL) { |
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7009 assert(obj->is_oop(), "expected an oop"); |
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7010 HeapWord* addr = (HeapWord*)obj; |
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7011 assert(_mark_stack->isEmpty(), "pre-condition (eager drainage)"); |
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7012 assert(_collector->overflow_list_is_empty(), |
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7013 "overflow list should be empty"); |
| 0 | 7014 if (_span.contains(addr) && |
| 7015 !_bit_map->isMarked(addr)) { | |
| 7016 // mark bit map (object is now grey) | |
| 7017 _bit_map->mark(addr); | |
| 7018 // push on marking stack (stack should be empty), and drain the | |
| 7019 // stack by applying this closure to the oops in the oops popped | |
| 7020 // from the stack (i.e. blacken the grey objects) | |
|
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7021 bool res = _mark_stack->push(obj); |
| 0 | 7022 assert(res, "Should have space to push on empty stack"); |
| 7023 do { | |
| 7024 oop new_oop = _mark_stack->pop(); | |
| 7025 assert(new_oop != NULL && new_oop->is_oop(), "Expected an oop"); | |
| 7026 assert(_bit_map->isMarked((HeapWord*)new_oop), | |
| 7027 "only grey objects on this stack"); | |
| 7028 // iterate over the oops in this oop, marking and pushing | |
| 7029 // the ones in CMS heap (i.e. in _span). | |
| 7030 new_oop->oop_iterate(&_pushAndMarkClosure); | |
| 7031 // check if it's time to yield | |
| 7032 do_yield_check(); | |
| 7033 } while (!_mark_stack->isEmpty() || | |
| 7034 (!_concurrent_precleaning && take_from_overflow_list())); | |
| 7035 // if marking stack is empty, and we are not doing this | |
| 7036 // during precleaning, then check the overflow list | |
| 7037 } | |
| 7038 assert(_mark_stack->isEmpty(), "post-condition (eager drainage)"); | |
| 7039 assert(_collector->overflow_list_is_empty(), | |
| 7040 "overflow list was drained above"); | |
| 7041 // We could restore evacuated mark words, if any, used for | |
| 7042 // overflow list links here because the overflow list is | |
| 7043 // provably empty here. That would reduce the maximum | |
| 7044 // size requirements for preserved_{oop,mark}_stack. | |
| 7045 // But we'll just postpone it until we are all done | |
| 7046 // so we can just stream through. | |
| 7047 if (!_concurrent_precleaning && CMSOverflowEarlyRestoration) { | |
| 7048 _collector->restore_preserved_marks_if_any(); | |
| 7049 assert(_collector->no_preserved_marks(), "No preserved marks"); | |
| 7050 } | |
| 7051 assert(!CMSOverflowEarlyRestoration || _collector->no_preserved_marks(), | |
| 7052 "All preserved marks should have been restored above"); | |
| 7053 } | |
| 7054 } | |
| 7055 | |
|
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7056 void MarkRefsIntoAndScanClosure::do_oop(oop* p) { MarkRefsIntoAndScanClosure::do_oop_work(p); } |
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7057 void MarkRefsIntoAndScanClosure::do_oop(narrowOop* p) { MarkRefsIntoAndScanClosure::do_oop_work(p); } |
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7058 |
| 0 | 7059 void MarkRefsIntoAndScanClosure::do_yield_work() { |
| 7060 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 7061 "CMS thread should hold CMS token"); | |
| 7062 assert_lock_strong(_freelistLock); | |
| 7063 assert_lock_strong(_bit_map->lock()); | |
| 7064 // relinquish the free_list_lock and bitMaplock() | |
| 7065 _bit_map->lock()->unlock(); | |
| 7066 _freelistLock->unlock(); | |
| 7067 ConcurrentMarkSweepThread::desynchronize(true); | |
| 7068 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7069 _collector->stopTimer(); | |
| 7070 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 7071 if (PrintCMSStatistics != 0) { | |
| 7072 _collector->incrementYields(); | |
| 7073 } | |
| 7074 _collector->icms_wait(); | |
| 7075 | |
| 7076 // See the comment in coordinator_yield() | |
|
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7077 for (unsigned i = 0; |
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7078 i < CMSYieldSleepCount && |
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7079 ConcurrentMarkSweepThread::should_yield() && |
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7080 !CMSCollector::foregroundGCIsActive(); |
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7081 ++i) { |
| 0 | 7082 os::sleep(Thread::current(), 1, false); |
| 7083 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7084 } | |
| 7085 | |
| 7086 ConcurrentMarkSweepThread::synchronize(true); | |
| 7087 _freelistLock->lock_without_safepoint_check(); | |
| 7088 _bit_map->lock()->lock_without_safepoint_check(); | |
| 7089 _collector->startTimer(); | |
| 7090 } | |
| 7091 | |
| 7092 /////////////////////////////////////////////////////////// | |
| 7093 // Par_MarkRefsIntoAndScanClosure: a parallel version of | |
| 7094 // MarkRefsIntoAndScanClosure | |
| 7095 /////////////////////////////////////////////////////////// | |
| 7096 Par_MarkRefsIntoAndScanClosure::Par_MarkRefsIntoAndScanClosure( | |
| 7097 CMSCollector* collector, MemRegion span, ReferenceProcessor* rp, | |
|
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7098 CMSBitMap* bit_map, OopTaskQueue* work_queue): |
| 0 | 7099 _span(span), |
| 7100 _bit_map(bit_map), | |
| 7101 _work_queue(work_queue), | |
| 7102 _low_water_mark(MIN2((uint)(work_queue->max_elems()/4), | |
| 7103 (uint)(CMSWorkQueueDrainThreshold * ParallelGCThreads))), | |
|
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7104 _par_pushAndMarkClosure(collector, span, rp, bit_map, work_queue) |
| 0 | 7105 { |
| 7106 _ref_processor = rp; | |
| 7107 assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL"); | |
| 7108 } | |
| 7109 | |
| 7110 // This closure is used to mark refs into the CMS generation at the | |
| 7111 // second (final) checkpoint, and to scan and transitively follow | |
| 7112 // the unmarked oops. The marks are made in the marking bit map and | |
| 7113 // the work_queue is used for keeping the (newly) grey objects during | |
| 7114 // the scan phase whence they are also available for stealing by parallel | |
| 7115 // threads. Since the marking bit map is shared, updates are | |
| 7116 // synchronized (via CAS). | |
|
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7117 void Par_MarkRefsIntoAndScanClosure::do_oop(oop obj) { |
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7118 if (obj != NULL) { |
| 0 | 7119 // Ignore mark word because this could be an already marked oop |
| 7120 // that may be chained at the end of the overflow list. | |
|
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7121 assert(obj->is_oop(true), "expected an oop"); |
|
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7122 HeapWord* addr = (HeapWord*)obj; |
| 0 | 7123 if (_span.contains(addr) && |
| 7124 !_bit_map->isMarked(addr)) { | |
| 7125 // mark bit map (object will become grey): | |
| 7126 // It is possible for several threads to be | |
| 7127 // trying to "claim" this object concurrently; | |
| 7128 // the unique thread that succeeds in marking the | |
| 7129 // object first will do the subsequent push on | |
| 7130 // to the work queue (or overflow list). | |
| 7131 if (_bit_map->par_mark(addr)) { | |
| 7132 // push on work_queue (which may not be empty), and trim the | |
| 7133 // queue to an appropriate length by applying this closure to | |
| 7134 // the oops in the oops popped from the stack (i.e. blacken the | |
| 7135 // grey objects) | |
|
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7136 bool res = _work_queue->push(obj); |
| 0 | 7137 assert(res, "Low water mark should be less than capacity?"); |
| 7138 trim_queue(_low_water_mark); | |
| 7139 } // Else, another thread claimed the object | |
| 7140 } | |
| 7141 } | |
| 7142 } | |
| 7143 | |
|
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7144 void Par_MarkRefsIntoAndScanClosure::do_oop(oop* p) { Par_MarkRefsIntoAndScanClosure::do_oop_work(p); } |
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7145 void Par_MarkRefsIntoAndScanClosure::do_oop(narrowOop* p) { Par_MarkRefsIntoAndScanClosure::do_oop_work(p); } |
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7146 |
| 0 | 7147 // This closure is used to rescan the marked objects on the dirty cards |
| 7148 // in the mod union table and the card table proper. | |
| 7149 size_t ScanMarkedObjectsAgainCarefullyClosure::do_object_careful_m( | |
| 7150 oop p, MemRegion mr) { | |
| 7151 | |
| 7152 size_t size = 0; | |
| 7153 HeapWord* addr = (HeapWord*)p; | |
| 7154 DEBUG_ONLY(_collector->verify_work_stacks_empty();) | |
| 7155 assert(_span.contains(addr), "we are scanning the CMS generation"); | |
| 7156 // check if it's time to yield | |
| 7157 if (do_yield_check()) { | |
| 7158 // We yielded for some foreground stop-world work, | |
| 7159 // and we have been asked to abort this ongoing preclean cycle. | |
| 7160 return 0; | |
| 7161 } | |
| 7162 if (_bitMap->isMarked(addr)) { | |
| 7163 // it's marked; is it potentially uninitialized? | |
| 187 | 7164 if (p->klass_or_null() != NULL) { |
| 0 | 7165 // an initialized object; ignore mark word in verification below |
| 7166 // since we are running concurrent with mutators | |
| 7167 assert(p->is_oop(true), "should be an oop"); | |
| 7168 if (p->is_objArray()) { | |
| 7169 // objArrays are precisely marked; restrict scanning | |
| 7170 // to dirty cards only. | |
| 187 | 7171 size = CompactibleFreeListSpace::adjustObjectSize( |
| 7172 p->oop_iterate(_scanningClosure, mr)); | |
| 0 | 7173 } else { |
| 7174 // A non-array may have been imprecisely marked; we need | |
| 7175 // to scan object in its entirety. | |
| 7176 size = CompactibleFreeListSpace::adjustObjectSize( | |
| 7177 p->oop_iterate(_scanningClosure)); | |
| 7178 } | |
| 9152 | 7179 #ifdef ASSERT |
| 0 | 7180 size_t direct_size = |
| 7181 CompactibleFreeListSpace::adjustObjectSize(p->size()); | |
| 7182 assert(size == direct_size, "Inconsistency in size"); | |
| 7183 assert(size >= 3, "Necessary for Printezis marks to work"); | |
| 7184 if (!_bitMap->isMarked(addr+1)) { | |
| 7185 _bitMap->verifyNoOneBitsInRange(addr+2, addr+size); | |
| 7186 } else { | |
| 7187 _bitMap->verifyNoOneBitsInRange(addr+2, addr+size-1); | |
| 7188 assert(_bitMap->isMarked(addr+size-1), | |
| 7189 "inconsistent Printezis mark"); | |
| 7190 } | |
| 9152 | 7191 #endif // ASSERT |
| 0 | 7192 } else { |
| 7193 // an unitialized object | |
| 7194 assert(_bitMap->isMarked(addr+1), "missing Printezis mark?"); | |
| 7195 HeapWord* nextOneAddr = _bitMap->getNextMarkedWordAddress(addr + 2); | |
| 7196 size = pointer_delta(nextOneAddr + 1, addr); | |
| 7197 assert(size == CompactibleFreeListSpace::adjustObjectSize(size), | |
| 7198 "alignment problem"); | |
| 7199 // Note that pre-cleaning needn't redirty the card. OopDesc::set_klass() | |
| 7200 // will dirty the card when the klass pointer is installed in the | |
| 7201 // object (signalling the completion of initialization). | |
| 7202 } | |
| 7203 } else { | |
| 7204 // Either a not yet marked object or an uninitialized object | |
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7205 if (p->klass_or_null() == NULL) { |
| 0 | 7206 // An uninitialized object, skip to the next card, since |
| 7207 // we may not be able to read its P-bits yet. | |
| 7208 assert(size == 0, "Initial value"); | |
| 7209 } else { | |
| 7210 // An object not (yet) reached by marking: we merely need to | |
| 7211 // compute its size so as to go look at the next block. | |
| 7212 assert(p->is_oop(true), "should be an oop"); | |
| 7213 size = CompactibleFreeListSpace::adjustObjectSize(p->size()); | |
| 7214 } | |
| 7215 } | |
| 7216 DEBUG_ONLY(_collector->verify_work_stacks_empty();) | |
| 7217 return size; | |
| 7218 } | |
| 7219 | |
| 7220 void ScanMarkedObjectsAgainCarefullyClosure::do_yield_work() { | |
| 7221 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 7222 "CMS thread should hold CMS token"); | |
| 7223 assert_lock_strong(_freelistLock); | |
| 7224 assert_lock_strong(_bitMap->lock()); | |
| 7225 // relinquish the free_list_lock and bitMaplock() | |
| 7226 _bitMap->lock()->unlock(); | |
| 7227 _freelistLock->unlock(); | |
| 7228 ConcurrentMarkSweepThread::desynchronize(true); | |
| 7229 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7230 _collector->stopTimer(); | |
| 7231 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 7232 if (PrintCMSStatistics != 0) { | |
| 7233 _collector->incrementYields(); | |
| 7234 } | |
| 7235 _collector->icms_wait(); | |
| 7236 | |
| 7237 // See the comment in coordinator_yield() | |
| 7238 for (unsigned i = 0; i < CMSYieldSleepCount && | |
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7239 ConcurrentMarkSweepThread::should_yield() && |
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7240 !CMSCollector::foregroundGCIsActive(); ++i) { |
| 0 | 7241 os::sleep(Thread::current(), 1, false); |
| 7242 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7243 } | |
| 7244 | |
| 7245 ConcurrentMarkSweepThread::synchronize(true); | |
| 7246 _freelistLock->lock_without_safepoint_check(); | |
| 7247 _bitMap->lock()->lock_without_safepoint_check(); | |
| 7248 _collector->startTimer(); | |
| 7249 } | |
| 7250 | |
| 7251 | |
| 7252 ////////////////////////////////////////////////////////////////// | |
| 7253 // SurvivorSpacePrecleanClosure | |
| 7254 ////////////////////////////////////////////////////////////////// | |
| 7255 // This (single-threaded) closure is used to preclean the oops in | |
| 7256 // the survivor spaces. | |
| 7257 size_t SurvivorSpacePrecleanClosure::do_object_careful(oop p) { | |
| 7258 | |
| 7259 HeapWord* addr = (HeapWord*)p; | |
| 7260 DEBUG_ONLY(_collector->verify_work_stacks_empty();) | |
| 7261 assert(!_span.contains(addr), "we are scanning the survivor spaces"); | |
| 187 | 7262 assert(p->klass_or_null() != NULL, "object should be initializd"); |
| 0 | 7263 // an initialized object; ignore mark word in verification below |
| 7264 // since we are running concurrent with mutators | |
| 7265 assert(p->is_oop(true), "should be an oop"); | |
| 7266 // Note that we do not yield while we iterate over | |
| 7267 // the interior oops of p, pushing the relevant ones | |
| 7268 // on our marking stack. | |
| 7269 size_t size = p->oop_iterate(_scanning_closure); | |
| 7270 do_yield_check(); | |
| 7271 // Observe that below, we do not abandon the preclean | |
| 7272 // phase as soon as we should; rather we empty the | |
| 7273 // marking stack before returning. This is to satisfy | |
| 7274 // some existing assertions. In general, it may be a | |
| 7275 // good idea to abort immediately and complete the marking | |
| 7276 // from the grey objects at a later time. | |
| 7277 while (!_mark_stack->isEmpty()) { | |
| 7278 oop new_oop = _mark_stack->pop(); | |
| 7279 assert(new_oop != NULL && new_oop->is_oop(), "Expected an oop"); | |
| 7280 assert(_bit_map->isMarked((HeapWord*)new_oop), | |
| 7281 "only grey objects on this stack"); | |
| 7282 // iterate over the oops in this oop, marking and pushing | |
| 7283 // the ones in CMS heap (i.e. in _span). | |
| 7284 new_oop->oop_iterate(_scanning_closure); | |
| 7285 // check if it's time to yield | |
| 7286 do_yield_check(); | |
| 7287 } | |
| 7288 unsigned int after_count = | |
| 7289 GenCollectedHeap::heap()->total_collections(); | |
| 7290 bool abort = (_before_count != after_count) || | |
| 7291 _collector->should_abort_preclean(); | |
| 7292 return abort ? 0 : size; | |
| 7293 } | |
| 7294 | |
| 7295 void SurvivorSpacePrecleanClosure::do_yield_work() { | |
| 7296 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 7297 "CMS thread should hold CMS token"); | |
| 7298 assert_lock_strong(_bit_map->lock()); | |
| 7299 // Relinquish the bit map lock | |
| 7300 _bit_map->lock()->unlock(); | |
| 7301 ConcurrentMarkSweepThread::desynchronize(true); | |
| 7302 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7303 _collector->stopTimer(); | |
| 7304 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 7305 if (PrintCMSStatistics != 0) { | |
| 7306 _collector->incrementYields(); | |
| 7307 } | |
| 7308 _collector->icms_wait(); | |
| 7309 | |
| 7310 // See the comment in coordinator_yield() | |
| 7311 for (unsigned i = 0; i < CMSYieldSleepCount && | |
| 7312 ConcurrentMarkSweepThread::should_yield() && | |
| 7313 !CMSCollector::foregroundGCIsActive(); ++i) { | |
| 7314 os::sleep(Thread::current(), 1, false); | |
| 7315 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7316 } | |
| 7317 | |
| 7318 ConcurrentMarkSweepThread::synchronize(true); | |
| 7319 _bit_map->lock()->lock_without_safepoint_check(); | |
| 7320 _collector->startTimer(); | |
| 7321 } | |
| 7322 | |
| 7323 // This closure is used to rescan the marked objects on the dirty cards | |
| 7324 // in the mod union table and the card table proper. In the parallel | |
| 7325 // case, although the bitMap is shared, we do a single read so the | |
| 7326 // isMarked() query is "safe". | |
| 7327 bool ScanMarkedObjectsAgainClosure::do_object_bm(oop p, MemRegion mr) { | |
| 7328 // Ignore mark word because we are running concurrent with mutators | |
| 7329 assert(p->is_oop_or_null(true), "expected an oop or null"); | |
| 7330 HeapWord* addr = (HeapWord*)p; | |
| 7331 assert(_span.contains(addr), "we are scanning the CMS generation"); | |
| 7332 bool is_obj_array = false; | |
| 9152 | 7333 #ifdef ASSERT |
| 0 | 7334 if (!_parallel) { |
| 7335 assert(_mark_stack->isEmpty(), "pre-condition (eager drainage)"); | |
| 7336 assert(_collector->overflow_list_is_empty(), | |
| 7337 "overflow list should be empty"); | |
| 7338 | |
| 7339 } | |
| 9152 | 7340 #endif // ASSERT |
| 0 | 7341 if (_bit_map->isMarked(addr)) { |
| 7342 // Obj arrays are precisely marked, non-arrays are not; | |
| 7343 // so we scan objArrays precisely and non-arrays in their | |
| 7344 // entirety. | |
| 7345 if (p->is_objArray()) { | |
| 7346 is_obj_array = true; | |
| 7347 if (_parallel) { | |
| 7348 p->oop_iterate(_par_scan_closure, mr); | |
| 7349 } else { | |
| 7350 p->oop_iterate(_scan_closure, mr); | |
| 7351 } | |
| 7352 } else { | |
| 7353 if (_parallel) { | |
| 7354 p->oop_iterate(_par_scan_closure); | |
| 7355 } else { | |
| 7356 p->oop_iterate(_scan_closure); | |
| 7357 } | |
| 7358 } | |
| 7359 } | |
| 9152 | 7360 #ifdef ASSERT |
| 0 | 7361 if (!_parallel) { |
| 7362 assert(_mark_stack->isEmpty(), "post-condition (eager drainage)"); | |
| 7363 assert(_collector->overflow_list_is_empty(), | |
| 7364 "overflow list should be empty"); | |
| 7365 | |
| 7366 } | |
| 9152 | 7367 #endif // ASSERT |
| 0 | 7368 return is_obj_array; |
| 7369 } | |
| 7370 | |
| 7371 MarkFromRootsClosure::MarkFromRootsClosure(CMSCollector* collector, | |
| 7372 MemRegion span, | |
| 7373 CMSBitMap* bitMap, CMSMarkStack* markStack, | |
| 7374 bool should_yield, bool verifying): | |
| 7375 _collector(collector), | |
| 7376 _span(span), | |
| 7377 _bitMap(bitMap), | |
| 7378 _mut(&collector->_modUnionTable), | |
| 7379 _markStack(markStack), | |
| 7380 _yield(should_yield), | |
| 7381 _skipBits(0) | |
| 7382 { | |
| 7383 assert(_markStack->isEmpty(), "stack should be empty"); | |
| 7384 _finger = _bitMap->startWord(); | |
| 7385 _threshold = _finger; | |
| 7386 assert(_collector->_restart_addr == NULL, "Sanity check"); | |
| 7387 assert(_span.contains(_finger), "Out of bounds _finger?"); | |
| 7388 DEBUG_ONLY(_verifying = verifying;) | |
| 7389 } | |
| 7390 | |
| 7391 void MarkFromRootsClosure::reset(HeapWord* addr) { | |
| 7392 assert(_markStack->isEmpty(), "would cause duplicates on stack"); | |
| 7393 assert(_span.contains(addr), "Out of bounds _finger?"); | |
| 7394 _finger = addr; | |
| 7395 _threshold = (HeapWord*)round_to( | |
| 7396 (intptr_t)_finger, CardTableModRefBS::card_size); | |
| 7397 } | |
| 7398 | |
| 7399 // Should revisit to see if this should be restructured for | |
| 7400 // greater efficiency. | |
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7401 bool MarkFromRootsClosure::do_bit(size_t offset) { |
| 0 | 7402 if (_skipBits > 0) { |
| 7403 _skipBits--; | |
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7404 return true; |
| 0 | 7405 } |
| 7406 // convert offset into a HeapWord* | |
| 7407 HeapWord* addr = _bitMap->startWord() + offset; | |
| 7408 assert(_bitMap->endWord() && addr < _bitMap->endWord(), | |
| 7409 "address out of range"); | |
| 7410 assert(_bitMap->isMarked(addr), "tautology"); | |
| 7411 if (_bitMap->isMarked(addr+1)) { | |
| 7412 // this is an allocated but not yet initialized object | |
| 7413 assert(_skipBits == 0, "tautology"); | |
| 7414 _skipBits = 2; // skip next two marked bits ("Printezis-marks") | |
| 7415 oop p = oop(addr); | |
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7416 if (p->klass_or_null() == NULL) { |
| 0 | 7417 DEBUG_ONLY(if (!_verifying) {) |
| 7418 // We re-dirty the cards on which this object lies and increase | |
| 7419 // the _threshold so that we'll come back to scan this object | |
| 7420 // during the preclean or remark phase. (CMSCleanOnEnter) | |
| 7421 if (CMSCleanOnEnter) { | |
| 7422 size_t sz = _collector->block_size_using_printezis_bits(addr); | |
| 7423 HeapWord* end_card_addr = (HeapWord*)round_to( | |
| 7424 (intptr_t)(addr+sz), CardTableModRefBS::card_size); | |
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7425 MemRegion redirty_range = MemRegion(addr, end_card_addr); |
| 0 | 7426 assert(!redirty_range.is_empty(), "Arithmetical tautology"); |
| 7427 // Bump _threshold to end_card_addr; note that | |
| 7428 // _threshold cannot possibly exceed end_card_addr, anyhow. | |
| 7429 // This prevents future clearing of the card as the scan proceeds | |
| 7430 // to the right. | |
| 7431 assert(_threshold <= end_card_addr, | |
| 7432 "Because we are just scanning into this object"); | |
| 7433 if (_threshold < end_card_addr) { | |
| 7434 _threshold = end_card_addr; | |
| 7435 } | |
| 187 | 7436 if (p->klass_or_null() != NULL) { |
| 0 | 7437 // Redirty the range of cards... |
| 7438 _mut->mark_range(redirty_range); | |
| 7439 } // ...else the setting of klass will dirty the card anyway. | |
| 7440 } | |
| 7441 DEBUG_ONLY(}) | |
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7442 return true; |
| 0 | 7443 } |
| 7444 } | |
| 7445 scanOopsInOop(addr); | |
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7446 return true; |
| 0 | 7447 } |
| 7448 | |
| 7449 // We take a break if we've been at this for a while, | |
| 7450 // so as to avoid monopolizing the locks involved. | |
| 7451 void MarkFromRootsClosure::do_yield_work() { | |
| 7452 // First give up the locks, then yield, then re-lock | |
| 7453 // We should probably use a constructor/destructor idiom to | |
| 7454 // do this unlock/lock or modify the MutexUnlocker class to | |
| 7455 // serve our purpose. XXX | |
| 7456 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 7457 "CMS thread should hold CMS token"); | |
| 7458 assert_lock_strong(_bitMap->lock()); | |
| 7459 _bitMap->lock()->unlock(); | |
| 7460 ConcurrentMarkSweepThread::desynchronize(true); | |
| 7461 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7462 _collector->stopTimer(); | |
| 7463 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 7464 if (PrintCMSStatistics != 0) { | |
| 7465 _collector->incrementYields(); | |
| 7466 } | |
| 7467 _collector->icms_wait(); | |
| 7468 | |
| 7469 // See the comment in coordinator_yield() | |
| 7470 for (unsigned i = 0; i < CMSYieldSleepCount && | |
| 7471 ConcurrentMarkSweepThread::should_yield() && | |
| 7472 !CMSCollector::foregroundGCIsActive(); ++i) { | |
| 7473 os::sleep(Thread::current(), 1, false); | |
| 7474 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7475 } | |
| 7476 | |
| 7477 ConcurrentMarkSweepThread::synchronize(true); | |
| 7478 _bitMap->lock()->lock_without_safepoint_check(); | |
| 7479 _collector->startTimer(); | |
| 7480 } | |
| 7481 | |
| 7482 void MarkFromRootsClosure::scanOopsInOop(HeapWord* ptr) { | |
| 7483 assert(_bitMap->isMarked(ptr), "expected bit to be set"); | |
| 7484 assert(_markStack->isEmpty(), | |
| 7485 "should drain stack to limit stack usage"); | |
| 7486 // convert ptr to an oop preparatory to scanning | |
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7487 oop obj = oop(ptr); |
| 0 | 7488 // Ignore mark word in verification below, since we |
| 7489 // may be running concurrent with mutators. | |
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7490 assert(obj->is_oop(true), "should be an oop"); |
| 0 | 7491 assert(_finger <= ptr, "_finger runneth ahead"); |
| 7492 // advance the finger to right end of this object | |
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7493 _finger = ptr + obj->size(); |
| 0 | 7494 assert(_finger > ptr, "we just incremented it above"); |
| 7495 // On large heaps, it may take us some time to get through | |
| 7496 // the marking phase (especially if running iCMS). During | |
| 7497 // this time it's possible that a lot of mutations have | |
| 7498 // accumulated in the card table and the mod union table -- | |
| 7499 // these mutation records are redundant until we have | |
| 7500 // actually traced into the corresponding card. | |
| 7501 // Here, we check whether advancing the finger would make | |
| 7502 // us cross into a new card, and if so clear corresponding | |
| 7503 // cards in the MUT (preclean them in the card-table in the | |
| 7504 // future). | |
| 7505 | |
| 7506 DEBUG_ONLY(if (!_verifying) {) | |
| 7507 // The clean-on-enter optimization is disabled by default, | |
| 7508 // until we fix 6178663. | |
| 7509 if (CMSCleanOnEnter && (_finger > _threshold)) { | |
| 7510 // [_threshold, _finger) represents the interval | |
| 7511 // of cards to be cleared in MUT (or precleaned in card table). | |
| 7512 // The set of cards to be cleared is all those that overlap | |
| 7513 // with the interval [_threshold, _finger); note that | |
| 7514 // _threshold is always kept card-aligned but _finger isn't | |
| 7515 // always card-aligned. | |
| 7516 HeapWord* old_threshold = _threshold; | |
| 7517 assert(old_threshold == (HeapWord*)round_to( | |
| 7518 (intptr_t)old_threshold, CardTableModRefBS::card_size), | |
| 7519 "_threshold should always be card-aligned"); | |
| 7520 _threshold = (HeapWord*)round_to( | |
| 7521 (intptr_t)_finger, CardTableModRefBS::card_size); | |
| 7522 MemRegion mr(old_threshold, _threshold); | |
| 7523 assert(!mr.is_empty(), "Control point invariant"); | |
| 7524 assert(_span.contains(mr), "Should clear within span"); | |
| 7525 _mut->clear_range(mr); | |
| 7526 } | |
| 7527 DEBUG_ONLY(}) | |
| 7528 // Note: the finger doesn't advance while we drain | |
| 7529 // the stack below. | |
| 7530 PushOrMarkClosure pushOrMarkClosure(_collector, | |
| 7531 _span, _bitMap, _markStack, | |
| 7532 _finger, this); | |
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7533 bool res = _markStack->push(obj); |
| 0 | 7534 assert(res, "Empty non-zero size stack should have space for single push"); |
| 7535 while (!_markStack->isEmpty()) { | |
| 7536 oop new_oop = _markStack->pop(); | |
| 7537 // Skip verifying header mark word below because we are | |
| 7538 // running concurrent with mutators. | |
| 7539 assert(new_oop->is_oop(true), "Oops! expected to pop an oop"); | |
| 7540 // now scan this oop's oops | |
| 7541 new_oop->oop_iterate(&pushOrMarkClosure); | |
| 7542 do_yield_check(); | |
| 7543 } | |
| 7544 assert(_markStack->isEmpty(), "tautology, emphasizing post-condition"); | |
| 7545 } | |
| 7546 | |
| 7547 Par_MarkFromRootsClosure::Par_MarkFromRootsClosure(CMSConcMarkingTask* task, | |
| 7548 CMSCollector* collector, MemRegion span, | |
| 7549 CMSBitMap* bit_map, | |
| 7550 OopTaskQueue* work_queue, | |
| 7551 CMSMarkStack* overflow_stack, | |
| 7552 bool should_yield): | |
| 7553 _collector(collector), | |
| 7554 _whole_span(collector->_span), | |
| 7555 _span(span), | |
| 7556 _bit_map(bit_map), | |
| 7557 _mut(&collector->_modUnionTable), | |
| 7558 _work_queue(work_queue), | |
| 7559 _overflow_stack(overflow_stack), | |
| 7560 _yield(should_yield), | |
| 7561 _skip_bits(0), | |
| 7562 _task(task) | |
| 7563 { | |
| 7564 assert(_work_queue->size() == 0, "work_queue should be empty"); | |
| 7565 _finger = span.start(); | |
| 7566 _threshold = _finger; // XXX Defer clear-on-enter optimization for now | |
| 7567 assert(_span.contains(_finger), "Out of bounds _finger?"); | |
| 7568 } | |
| 7569 | |
| 7570 // Should revisit to see if this should be restructured for | |
| 7571 // greater efficiency. | |
|
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7572 bool Par_MarkFromRootsClosure::do_bit(size_t offset) { |
| 0 | 7573 if (_skip_bits > 0) { |
| 7574 _skip_bits--; | |
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7575 return true; |
| 0 | 7576 } |
| 7577 // convert offset into a HeapWord* | |
| 7578 HeapWord* addr = _bit_map->startWord() + offset; | |
| 7579 assert(_bit_map->endWord() && addr < _bit_map->endWord(), | |
| 7580 "address out of range"); | |
| 7581 assert(_bit_map->isMarked(addr), "tautology"); | |
| 7582 if (_bit_map->isMarked(addr+1)) { | |
| 7583 // this is an allocated object that might not yet be initialized | |
| 7584 assert(_skip_bits == 0, "tautology"); | |
| 7585 _skip_bits = 2; // skip next two marked bits ("Printezis-marks") | |
| 7586 oop p = oop(addr); | |
|
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7587 if (p->klass_or_null() == NULL) { |
| 0 | 7588 // in the case of Clean-on-Enter optimization, redirty card |
| 7589 // and avoid clearing card by increasing the threshold. | |
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7590 return true; |
| 0 | 7591 } |
| 7592 } | |
| 7593 scan_oops_in_oop(addr); | |
|
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7594 return true; |
| 0 | 7595 } |
| 7596 | |
| 7597 void Par_MarkFromRootsClosure::scan_oops_in_oop(HeapWord* ptr) { | |
| 7598 assert(_bit_map->isMarked(ptr), "expected bit to be set"); | |
| 7599 // Should we assert that our work queue is empty or | |
| 7600 // below some drain limit? | |
| 7601 assert(_work_queue->size() == 0, | |
| 7602 "should drain stack to limit stack usage"); | |
| 7603 // convert ptr to an oop preparatory to scanning | |
|
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7604 oop obj = oop(ptr); |
| 0 | 7605 // Ignore mark word in verification below, since we |
| 7606 // may be running concurrent with mutators. | |
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7607 assert(obj->is_oop(true), "should be an oop"); |
| 0 | 7608 assert(_finger <= ptr, "_finger runneth ahead"); |
| 7609 // advance the finger to right end of this object | |
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7610 _finger = ptr + obj->size(); |
| 0 | 7611 assert(_finger > ptr, "we just incremented it above"); |
| 7612 // On large heaps, it may take us some time to get through | |
| 7613 // the marking phase (especially if running iCMS). During | |
| 7614 // this time it's possible that a lot of mutations have | |
| 7615 // accumulated in the card table and the mod union table -- | |
| 7616 // these mutation records are redundant until we have | |
| 7617 // actually traced into the corresponding card. | |
| 7618 // Here, we check whether advancing the finger would make | |
| 7619 // us cross into a new card, and if so clear corresponding | |
| 7620 // cards in the MUT (preclean them in the card-table in the | |
| 7621 // future). | |
| 7622 | |
| 7623 // The clean-on-enter optimization is disabled by default, | |
| 7624 // until we fix 6178663. | |
| 7625 if (CMSCleanOnEnter && (_finger > _threshold)) { | |
| 7626 // [_threshold, _finger) represents the interval | |
| 7627 // of cards to be cleared in MUT (or precleaned in card table). | |
| 7628 // The set of cards to be cleared is all those that overlap | |
| 7629 // with the interval [_threshold, _finger); note that | |
| 7630 // _threshold is always kept card-aligned but _finger isn't | |
| 7631 // always card-aligned. | |
| 7632 HeapWord* old_threshold = _threshold; | |
| 7633 assert(old_threshold == (HeapWord*)round_to( | |
| 7634 (intptr_t)old_threshold, CardTableModRefBS::card_size), | |
| 7635 "_threshold should always be card-aligned"); | |
| 7636 _threshold = (HeapWord*)round_to( | |
| 7637 (intptr_t)_finger, CardTableModRefBS::card_size); | |
| 7638 MemRegion mr(old_threshold, _threshold); | |
| 7639 assert(!mr.is_empty(), "Control point invariant"); | |
| 7640 assert(_span.contains(mr), "Should clear within span"); // _whole_span ?? | |
| 7641 _mut->clear_range(mr); | |
| 7642 } | |
| 7643 | |
| 7644 // Note: the local finger doesn't advance while we drain | |
| 7645 // the stack below, but the global finger sure can and will. | |
| 7646 HeapWord** gfa = _task->global_finger_addr(); | |
| 7647 Par_PushOrMarkClosure pushOrMarkClosure(_collector, | |
| 7648 _span, _bit_map, | |
| 7649 _work_queue, | |
| 7650 _overflow_stack, | |
| 7651 _finger, | |
| 7652 gfa, this); | |
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7653 bool res = _work_queue->push(obj); // overflow could occur here |
| 0 | 7654 assert(res, "Will hold once we use workqueues"); |
| 7655 while (true) { | |
| 7656 oop new_oop; | |
| 7657 if (!_work_queue->pop_local(new_oop)) { | |
| 7658 // We emptied our work_queue; check if there's stuff that can | |
| 7659 // be gotten from the overflow stack. | |
| 7660 if (CMSConcMarkingTask::get_work_from_overflow_stack( | |
| 7661 _overflow_stack, _work_queue)) { | |
| 7662 do_yield_check(); | |
| 7663 continue; | |
| 7664 } else { // done | |
| 7665 break; | |
| 7666 } | |
| 7667 } | |
| 7668 // Skip verifying header mark word below because we are | |
| 7669 // running concurrent with mutators. | |
| 7670 assert(new_oop->is_oop(true), "Oops! expected to pop an oop"); | |
| 7671 // now scan this oop's oops | |
| 7672 new_oop->oop_iterate(&pushOrMarkClosure); | |
| 7673 do_yield_check(); | |
| 7674 } | |
| 7675 assert(_work_queue->size() == 0, "tautology, emphasizing post-condition"); | |
| 7676 } | |
| 7677 | |
| 7678 // Yield in response to a request from VM Thread or | |
| 7679 // from mutators. | |
| 7680 void Par_MarkFromRootsClosure::do_yield_work() { | |
| 7681 assert(_task != NULL, "sanity"); | |
| 7682 _task->yield(); | |
| 7683 } | |
| 7684 | |
| 7685 // A variant of the above used for verifying CMS marking work. | |
| 7686 MarkFromRootsVerifyClosure::MarkFromRootsVerifyClosure(CMSCollector* collector, | |
| 7687 MemRegion span, | |
| 7688 CMSBitMap* verification_bm, CMSBitMap* cms_bm, | |
| 7689 CMSMarkStack* mark_stack): | |
| 7690 _collector(collector), | |
| 7691 _span(span), | |
| 7692 _verification_bm(verification_bm), | |
| 7693 _cms_bm(cms_bm), | |
| 7694 _mark_stack(mark_stack), | |
| 7695 _pam_verify_closure(collector, span, verification_bm, cms_bm, | |
| 7696 mark_stack) | |
| 7697 { | |
| 7698 assert(_mark_stack->isEmpty(), "stack should be empty"); | |
| 7699 _finger = _verification_bm->startWord(); | |
| 7700 assert(_collector->_restart_addr == NULL, "Sanity check"); | |
| 7701 assert(_span.contains(_finger), "Out of bounds _finger?"); | |
| 7702 } | |
| 7703 | |
| 7704 void MarkFromRootsVerifyClosure::reset(HeapWord* addr) { | |
| 7705 assert(_mark_stack->isEmpty(), "would cause duplicates on stack"); | |
| 7706 assert(_span.contains(addr), "Out of bounds _finger?"); | |
| 7707 _finger = addr; | |
| 7708 } | |
| 7709 | |
| 7710 // Should revisit to see if this should be restructured for | |
| 7711 // greater efficiency. | |
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7712 bool MarkFromRootsVerifyClosure::do_bit(size_t offset) { |
| 0 | 7713 // convert offset into a HeapWord* |
| 7714 HeapWord* addr = _verification_bm->startWord() + offset; | |
| 7715 assert(_verification_bm->endWord() && addr < _verification_bm->endWord(), | |
| 7716 "address out of range"); | |
| 7717 assert(_verification_bm->isMarked(addr), "tautology"); | |
| 7718 assert(_cms_bm->isMarked(addr), "tautology"); | |
| 7719 | |
| 7720 assert(_mark_stack->isEmpty(), | |
| 7721 "should drain stack to limit stack usage"); | |
| 7722 // convert addr to an oop preparatory to scanning | |
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7723 oop obj = oop(addr); |
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7724 assert(obj->is_oop(), "should be an oop"); |
| 0 | 7725 assert(_finger <= addr, "_finger runneth ahead"); |
| 7726 // advance the finger to right end of this object | |
|
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7727 _finger = addr + obj->size(); |
| 0 | 7728 assert(_finger > addr, "we just incremented it above"); |
| 7729 // Note: the finger doesn't advance while we drain | |
| 7730 // the stack below. | |
|
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7731 bool res = _mark_stack->push(obj); |
| 0 | 7732 assert(res, "Empty non-zero size stack should have space for single push"); |
| 7733 while (!_mark_stack->isEmpty()) { | |
| 7734 oop new_oop = _mark_stack->pop(); | |
| 7735 assert(new_oop->is_oop(), "Oops! expected to pop an oop"); | |
| 7736 // now scan this oop's oops | |
| 7737 new_oop->oop_iterate(&_pam_verify_closure); | |
| 7738 } | |
| 7739 assert(_mark_stack->isEmpty(), "tautology, emphasizing post-condition"); | |
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7740 return true; |
| 0 | 7741 } |
| 7742 | |
| 7743 PushAndMarkVerifyClosure::PushAndMarkVerifyClosure( | |
| 7744 CMSCollector* collector, MemRegion span, | |
| 7745 CMSBitMap* verification_bm, CMSBitMap* cms_bm, | |
| 7746 CMSMarkStack* mark_stack): | |
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7747 CMSOopClosure(collector->ref_processor()), |
| 0 | 7748 _collector(collector), |
| 7749 _span(span), | |
| 7750 _verification_bm(verification_bm), | |
| 7751 _cms_bm(cms_bm), | |
| 7752 _mark_stack(mark_stack) | |
| 7753 { } | |
| 7754 | |
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7755 void PushAndMarkVerifyClosure::do_oop(oop* p) { PushAndMarkVerifyClosure::do_oop_work(p); } |
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7756 void PushAndMarkVerifyClosure::do_oop(narrowOop* p) { PushAndMarkVerifyClosure::do_oop_work(p); } |
| 0 | 7757 |
| 7758 // Upon stack overflow, we discard (part of) the stack, | |
| 7759 // remembering the least address amongst those discarded | |
| 7760 // in CMSCollector's _restart_address. | |
| 7761 void PushAndMarkVerifyClosure::handle_stack_overflow(HeapWord* lost) { | |
| 7762 // Remember the least grey address discarded | |
| 7763 HeapWord* ra = (HeapWord*)_mark_stack->least_value(lost); | |
| 7764 _collector->lower_restart_addr(ra); | |
| 7765 _mark_stack->reset(); // discard stack contents | |
| 7766 _mark_stack->expand(); // expand the stack if possible | |
| 7767 } | |
| 7768 | |
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7769 void PushAndMarkVerifyClosure::do_oop(oop obj) { |
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7770 assert(obj->is_oop_or_null(), "expected an oop or NULL"); |
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7771 HeapWord* addr = (HeapWord*)obj; |
| 0 | 7772 if (_span.contains(addr) && !_verification_bm->isMarked(addr)) { |
| 7773 // Oop lies in _span and isn't yet grey or black | |
| 7774 _verification_bm->mark(addr); // now grey | |
| 7775 if (!_cms_bm->isMarked(addr)) { | |
| 7776 oop(addr)->print(); | |
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7777 gclog_or_tty->print_cr(" (" INTPTR_FORMAT " should have been marked)", |
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7778 addr); |
| 0 | 7779 fatal("... aborting"); |
| 7780 } | |
| 7781 | |
|
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7782 if (!_mark_stack->push(obj)) { // stack overflow |
| 0 | 7783 if (PrintCMSStatistics != 0) { |
| 7784 gclog_or_tty->print_cr("CMS marking stack overflow (benign) at " | |
| 7785 SIZE_FORMAT, _mark_stack->capacity()); | |
| 7786 } | |
| 7787 assert(_mark_stack->isFull(), "Else push should have succeeded"); | |
| 7788 handle_stack_overflow(addr); | |
| 7789 } | |
| 7790 // anything including and to the right of _finger | |
| 7791 // will be scanned as we iterate over the remainder of the | |
| 7792 // bit map | |
| 7793 } | |
| 7794 } | |
| 7795 | |
| 7796 PushOrMarkClosure::PushOrMarkClosure(CMSCollector* collector, | |
| 7797 MemRegion span, | |
| 7798 CMSBitMap* bitMap, CMSMarkStack* markStack, | |
| 7799 HeapWord* finger, MarkFromRootsClosure* parent) : | |
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7800 CMSOopClosure(collector->ref_processor()), |
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7801 _collector(collector), |
| 0 | 7802 _span(span), |
| 7803 _bitMap(bitMap), | |
| 7804 _markStack(markStack), | |
| 7805 _finger(finger), | |
| 935 | 7806 _parent(parent) |
| 0 | 7807 { } |
| 7808 | |
| 7809 Par_PushOrMarkClosure::Par_PushOrMarkClosure(CMSCollector* collector, | |
| 7810 MemRegion span, | |
| 7811 CMSBitMap* bit_map, | |
| 7812 OopTaskQueue* work_queue, | |
| 7813 CMSMarkStack* overflow_stack, | |
| 7814 HeapWord* finger, | |
| 7815 HeapWord** global_finger_addr, | |
| 7816 Par_MarkFromRootsClosure* parent) : | |
|
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7817 CMSOopClosure(collector->ref_processor()), |
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7818 _collector(collector), |
| 0 | 7819 _whole_span(collector->_span), |
| 7820 _span(span), | |
| 7821 _bit_map(bit_map), | |
| 7822 _work_queue(work_queue), | |
| 7823 _overflow_stack(overflow_stack), | |
| 7824 _finger(finger), | |
| 7825 _global_finger_addr(global_finger_addr), | |
| 935 | 7826 _parent(parent) |
| 0 | 7827 { } |
| 7828 | |
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7829 // Assumes thread-safe access by callers, who are |
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7830 // responsible for mutual exclusion. |
| 0 | 7831 void CMSCollector::lower_restart_addr(HeapWord* low) { |
| 7832 assert(_span.contains(low), "Out of bounds addr"); | |
| 7833 if (_restart_addr == NULL) { | |
| 7834 _restart_addr = low; | |
| 7835 } else { | |
| 7836 _restart_addr = MIN2(_restart_addr, low); | |
| 7837 } | |
| 7838 } | |
| 7839 | |
| 7840 // Upon stack overflow, we discard (part of) the stack, | |
| 7841 // remembering the least address amongst those discarded | |
| 7842 // in CMSCollector's _restart_address. | |
| 7843 void PushOrMarkClosure::handle_stack_overflow(HeapWord* lost) { | |
| 7844 // Remember the least grey address discarded | |
| 7845 HeapWord* ra = (HeapWord*)_markStack->least_value(lost); | |
| 7846 _collector->lower_restart_addr(ra); | |
| 7847 _markStack->reset(); // discard stack contents | |
| 7848 _markStack->expand(); // expand the stack if possible | |
| 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 Par_PushOrMarkClosure::handle_stack_overflow(HeapWord* lost) { | |
| 7855 // We need to do this under a mutex to prevent other | |
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7856 // workers from interfering with the work done below. |
| 0 | 7857 MutexLockerEx ml(_overflow_stack->par_lock(), |
| 7858 Mutex::_no_safepoint_check_flag); | |
| 7859 // Remember the least grey address discarded | |
| 7860 HeapWord* ra = (HeapWord*)_overflow_stack->least_value(lost); | |
| 7861 _collector->lower_restart_addr(ra); | |
| 7862 _overflow_stack->reset(); // discard stack contents | |
| 7863 _overflow_stack->expand(); // expand the stack if possible | |
| 7864 } | |
| 7865 | |
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7866 void CMKlassClosure::do_klass(Klass* k) { |
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7867 assert(_oop_closure != NULL, "Not initialized?"); |
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7868 k->oops_do(_oop_closure); |
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7869 } |
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7870 |
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7871 void PushOrMarkClosure::do_oop(oop obj) { |
| 0 | 7872 // Ignore mark word because we are running concurrent with mutators. |
|
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7873 assert(obj->is_oop_or_null(true), "expected an oop or NULL"); |
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7874 HeapWord* addr = (HeapWord*)obj; |
| 0 | 7875 if (_span.contains(addr) && !_bitMap->isMarked(addr)) { |
| 7876 // Oop lies in _span and isn't yet grey or black | |
| 7877 _bitMap->mark(addr); // now grey | |
| 7878 if (addr < _finger) { | |
| 7879 // the bit map iteration has already either passed, or | |
| 7880 // sampled, this bit in the bit map; we'll need to | |
| 7881 // use the marking stack to scan this oop's oops. | |
| 7882 bool simulate_overflow = false; | |
| 7883 NOT_PRODUCT( | |
| 7884 if (CMSMarkStackOverflowALot && | |
| 7885 _collector->simulate_overflow()) { | |
| 7886 // simulate a stack overflow | |
| 7887 simulate_overflow = true; | |
| 7888 } | |
| 7889 ) | |
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7890 if (simulate_overflow || !_markStack->push(obj)) { // stack overflow |
| 0 | 7891 if (PrintCMSStatistics != 0) { |
| 7892 gclog_or_tty->print_cr("CMS marking stack overflow (benign) at " | |
| 7893 SIZE_FORMAT, _markStack->capacity()); | |
| 7894 } | |
| 7895 assert(simulate_overflow || _markStack->isFull(), "Else push should have succeeded"); | |
| 7896 handle_stack_overflow(addr); | |
| 7897 } | |
| 7898 } | |
| 7899 // anything including and to the right of _finger | |
| 7900 // will be scanned as we iterate over the remainder of the | |
| 7901 // bit map | |
| 7902 do_yield_check(); | |
| 7903 } | |
| 7904 } | |
| 7905 | |
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7906 void PushOrMarkClosure::do_oop(oop* p) { PushOrMarkClosure::do_oop_work(p); } |
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7907 void PushOrMarkClosure::do_oop(narrowOop* p) { PushOrMarkClosure::do_oop_work(p); } |
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7908 |
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7909 void Par_PushOrMarkClosure::do_oop(oop obj) { |
| 0 | 7910 // Ignore mark word because we are running concurrent with mutators. |
|
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7911 assert(obj->is_oop_or_null(true), "expected an oop or NULL"); |
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7912 HeapWord* addr = (HeapWord*)obj; |
| 0 | 7913 if (_whole_span.contains(addr) && !_bit_map->isMarked(addr)) { |
| 7914 // Oop lies in _span and isn't yet grey or black | |
| 7915 // We read the global_finger (volatile read) strictly after marking oop | |
| 7916 bool res = _bit_map->par_mark(addr); // now grey | |
| 7917 volatile HeapWord** gfa = (volatile HeapWord**)_global_finger_addr; | |
| 7918 // Should we push this marked oop on our stack? | |
| 7919 // -- if someone else marked it, nothing to do | |
| 7920 // -- if target oop is above global finger nothing to do | |
| 7921 // -- if target oop is in chunk and above local finger | |
| 7922 // then nothing to do | |
| 7923 // -- else push on work queue | |
| 7924 if ( !res // someone else marked it, they will deal with it | |
| 7925 || (addr >= *gfa) // will be scanned in a later task | |
| 7926 || (_span.contains(addr) && addr >= _finger)) { // later in this chunk | |
| 7927 return; | |
| 7928 } | |
| 7929 // the bit map iteration has already either passed, or | |
| 7930 // sampled, this bit in the bit map; we'll need to | |
| 7931 // use the marking stack to scan this oop's oops. | |
| 7932 bool simulate_overflow = false; | |
| 7933 NOT_PRODUCT( | |
| 7934 if (CMSMarkStackOverflowALot && | |
| 7935 _collector->simulate_overflow()) { | |
| 7936 // simulate a stack overflow | |
| 7937 simulate_overflow = true; | |
| 7938 } | |
| 7939 ) | |
| 7940 if (simulate_overflow || | |
|
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7941 !(_work_queue->push(obj) || _overflow_stack->par_push(obj))) { |
| 0 | 7942 // stack overflow |
| 7943 if (PrintCMSStatistics != 0) { | |
| 7944 gclog_or_tty->print_cr("CMS marking stack overflow (benign) at " | |
| 7945 SIZE_FORMAT, _overflow_stack->capacity()); | |
| 7946 } | |
| 7947 // We cannot assert that the overflow stack is full because | |
| 7948 // it may have been emptied since. | |
| 7949 assert(simulate_overflow || | |
| 7950 _work_queue->size() == _work_queue->max_elems(), | |
| 7951 "Else push should have succeeded"); | |
| 7952 handle_stack_overflow(addr); | |
| 7953 } | |
| 7954 do_yield_check(); | |
| 7955 } | |
| 7956 } | |
| 7957 | |
|
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7958 void Par_PushOrMarkClosure::do_oop(oop* p) { Par_PushOrMarkClosure::do_oop_work(p); } |
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7959 void Par_PushOrMarkClosure::do_oop(narrowOop* p) { Par_PushOrMarkClosure::do_oop_work(p); } |
| 0 | 7960 |
| 7961 PushAndMarkClosure::PushAndMarkClosure(CMSCollector* collector, | |
| 7962 MemRegion span, | |
| 7963 ReferenceProcessor* rp, | |
| 7964 CMSBitMap* bit_map, | |
| 7965 CMSBitMap* mod_union_table, | |
| 7966 CMSMarkStack* mark_stack, | |
| 7967 bool concurrent_precleaning): | |
|
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7968 CMSOopClosure(rp), |
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7969 _collector(collector), |
| 0 | 7970 _span(span), |
| 7971 _bit_map(bit_map), | |
| 7972 _mod_union_table(mod_union_table), | |
| 7973 _mark_stack(mark_stack), | |
| 935 | 7974 _concurrent_precleaning(concurrent_precleaning) |
| 0 | 7975 { |
| 7976 assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL"); | |
| 7977 } | |
| 7978 | |
| 7979 // Grey object rescan during pre-cleaning and second checkpoint phases -- | |
| 7980 // the non-parallel version (the parallel version appears further below.) | |
|
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7981 void PushAndMarkClosure::do_oop(oop obj) { |
|
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7982 // Ignore mark word verification. If during concurrent precleaning, |
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7983 // the object monitor may be locked. If during the checkpoint |
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7984 // phases, the object may already have been reached by a different |
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7985 // path and may be at the end of the global overflow list (so |
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7986 // the mark word may be NULL). |
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7987 assert(obj->is_oop_or_null(true /* ignore mark word */), |
| 0 | 7988 "expected an oop or NULL"); |
|
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7989 HeapWord* addr = (HeapWord*)obj; |
| 0 | 7990 // Check if oop points into the CMS generation |
| 7991 // and is not marked | |
| 7992 if (_span.contains(addr) && !_bit_map->isMarked(addr)) { | |
| 7993 // a white object ... | |
| 7994 _bit_map->mark(addr); // ... now grey | |
| 7995 // push on the marking stack (grey set) | |
| 7996 bool simulate_overflow = false; | |
| 7997 NOT_PRODUCT( | |
| 7998 if (CMSMarkStackOverflowALot && | |
| 7999 _collector->simulate_overflow()) { | |
| 8000 // simulate a stack overflow | |
| 8001 simulate_overflow = true; | |
| 8002 } | |
| 8003 ) | |
|
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8004 if (simulate_overflow || !_mark_stack->push(obj)) { |
| 0 | 8005 if (_concurrent_precleaning) { |
|
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8006 // During precleaning we can just dirty the appropriate card(s) |
| 0 | 8007 // in the mod union table, thus ensuring that the object remains |
|
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8008 // in the grey set and continue. In the case of object arrays |
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8009 // we need to dirty all of the cards that the object spans, |
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8010 // since the rescan of object arrays will be limited to the |
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8011 // dirty cards. |
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8012 // Note that no one can be intefering with us in this action |
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8013 // of dirtying the mod union table, so no locking or atomics |
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8014 // are required. |
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8015 if (obj->is_objArray()) { |
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8016 size_t sz = obj->size(); |
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8017 HeapWord* end_card_addr = (HeapWord*)round_to( |
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8018 (intptr_t)(addr+sz), CardTableModRefBS::card_size); |
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8019 MemRegion redirty_range = MemRegion(addr, end_card_addr); |
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8020 assert(!redirty_range.is_empty(), "Arithmetical tautology"); |
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8021 _mod_union_table->mark_range(redirty_range); |
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8022 } else { |
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8023 _mod_union_table->mark(addr); |
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8024 } |
| 0 | 8025 _collector->_ser_pmc_preclean_ovflw++; |
| 8026 } else { | |
| 8027 // During the remark phase, we need to remember this oop | |
| 8028 // in the overflow list. | |
|
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8029 _collector->push_on_overflow_list(obj); |
| 0 | 8030 _collector->_ser_pmc_remark_ovflw++; |
| 8031 } | |
| 8032 } | |
| 8033 } | |
| 8034 } | |
| 8035 | |
| 8036 Par_PushAndMarkClosure::Par_PushAndMarkClosure(CMSCollector* collector, | |
| 8037 MemRegion span, | |
| 8038 ReferenceProcessor* rp, | |
| 8039 CMSBitMap* bit_map, | |
|
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8040 OopTaskQueue* work_queue): |
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8041 CMSOopClosure(rp), |
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8042 _collector(collector), |
| 0 | 8043 _span(span), |
| 8044 _bit_map(bit_map), | |
| 935 | 8045 _work_queue(work_queue) |
| 0 | 8046 { |
| 8047 assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL"); | |
| 8048 } | |
| 8049 | |
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8050 void PushAndMarkClosure::do_oop(oop* p) { PushAndMarkClosure::do_oop_work(p); } |
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8051 void PushAndMarkClosure::do_oop(narrowOop* p) { PushAndMarkClosure::do_oop_work(p); } |
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8052 |
| 0 | 8053 // Grey object rescan during second checkpoint phase -- |
| 8054 // the parallel version. | |
|
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8055 void Par_PushAndMarkClosure::do_oop(oop obj) { |
| 0 | 8056 // In the assert below, we ignore the mark word because |
| 8057 // this oop may point to an already visited object that is | |
| 8058 // on the overflow stack (in which case the mark word has | |
| 8059 // been hijacked for chaining into the overflow stack -- | |
| 8060 // if this is the last object in the overflow stack then | |
| 8061 // its mark word will be NULL). Because this object may | |
| 8062 // have been subsequently popped off the global overflow | |
| 8063 // stack, and the mark word possibly restored to the prototypical | |
| 8064 // value, by the time we get to examined this failing assert in | |
| 8065 // the debugger, is_oop_or_null(false) may subsequently start | |
| 8066 // to hold. | |
|
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8067 assert(obj->is_oop_or_null(true), |
| 0 | 8068 "expected an oop or NULL"); |
|
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8069 HeapWord* addr = (HeapWord*)obj; |
| 0 | 8070 // Check if oop points into the CMS generation |
| 8071 // and is not marked | |
| 8072 if (_span.contains(addr) && !_bit_map->isMarked(addr)) { | |
| 8073 // a white object ... | |
| 8074 // If we manage to "claim" the object, by being the | |
| 8075 // first thread to mark it, then we push it on our | |
| 8076 // marking stack | |
| 8077 if (_bit_map->par_mark(addr)) { // ... now grey | |
| 8078 // push on work queue (grey set) | |
| 8079 bool simulate_overflow = false; | |
| 8080 NOT_PRODUCT( | |
| 8081 if (CMSMarkStackOverflowALot && | |
| 8082 _collector->par_simulate_overflow()) { | |
| 8083 // simulate a stack overflow | |
| 8084 simulate_overflow = true; | |
| 8085 } | |
| 8086 ) | |
|
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8087 if (simulate_overflow || !_work_queue->push(obj)) { |
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8088 _collector->par_push_on_overflow_list(obj); |
| 0 | 8089 _collector->_par_pmc_remark_ovflw++; // imprecise OK: no need to CAS |
| 8090 } | |
| 8091 } // Else, some other thread got there first | |
| 8092 } | |
| 8093 } | |
| 8094 | |
|
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8095 void Par_PushAndMarkClosure::do_oop(oop* p) { Par_PushAndMarkClosure::do_oop_work(p); } |
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8096 void Par_PushAndMarkClosure::do_oop(narrowOop* p) { Par_PushAndMarkClosure::do_oop_work(p); } |
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8097 |
| 0 | 8098 void CMSPrecleanRefsYieldClosure::do_yield_work() { |
| 8099 Mutex* bml = _collector->bitMapLock(); | |
| 8100 assert_lock_strong(bml); | |
| 8101 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 8102 "CMS thread should hold CMS token"); | |
| 8103 | |
| 8104 bml->unlock(); | |
| 8105 ConcurrentMarkSweepThread::desynchronize(true); | |
| 8106 | |
| 8107 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 8108 | |
| 8109 _collector->stopTimer(); | |
| 8110 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 8111 if (PrintCMSStatistics != 0) { | |
| 8112 _collector->incrementYields(); | |
| 8113 } | |
| 8114 _collector->icms_wait(); | |
| 8115 | |
| 8116 // See the comment in coordinator_yield() | |
| 8117 for (unsigned i = 0; i < CMSYieldSleepCount && | |
| 8118 ConcurrentMarkSweepThread::should_yield() && | |
| 8119 !CMSCollector::foregroundGCIsActive(); ++i) { | |
| 8120 os::sleep(Thread::current(), 1, false); | |
| 8121 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 8122 } | |
| 8123 | |
| 8124 ConcurrentMarkSweepThread::synchronize(true); | |
| 8125 bml->lock(); | |
| 8126 | |
| 8127 _collector->startTimer(); | |
| 8128 } | |
| 8129 | |
| 8130 bool CMSPrecleanRefsYieldClosure::should_return() { | |
| 8131 if (ConcurrentMarkSweepThread::should_yield()) { | |
| 8132 do_yield_work(); | |
| 8133 } | |
| 8134 return _collector->foregroundGCIsActive(); | |
| 8135 } | |
| 8136 | |
| 8137 void MarkFromDirtyCardsClosure::do_MemRegion(MemRegion mr) { | |
| 8138 assert(((size_t)mr.start())%CardTableModRefBS::card_size_in_words == 0, | |
| 8139 "mr should be aligned to start at a card boundary"); | |
| 8140 // We'd like to assert: | |
| 8141 // assert(mr.word_size()%CardTableModRefBS::card_size_in_words == 0, | |
| 8142 // "mr should be a range of cards"); | |
| 8143 // However, that would be too strong in one case -- the last | |
| 8144 // partition ends at _unallocated_block which, in general, can be | |
| 8145 // an arbitrary boundary, not necessarily card aligned. | |
| 8146 if (PrintCMSStatistics != 0) { | |
| 8147 _num_dirty_cards += | |
| 8148 mr.word_size()/CardTableModRefBS::card_size_in_words; | |
| 8149 } | |
| 8150 _space->object_iterate_mem(mr, &_scan_cl); | |
| 8151 } | |
| 8152 | |
| 8153 SweepClosure::SweepClosure(CMSCollector* collector, | |
| 8154 ConcurrentMarkSweepGeneration* g, | |
| 8155 CMSBitMap* bitMap, bool should_yield) : | |
| 8156 _collector(collector), | |
| 8157 _g(g), | |
| 8158 _sp(g->cmsSpace()), | |
| 8159 _limit(_sp->sweep_limit()), | |
| 8160 _freelistLock(_sp->freelistLock()), | |
| 8161 _bitMap(bitMap), | |
| 8162 _yield(should_yield), | |
| 8163 _inFreeRange(false), // No free range at beginning of sweep | |
| 8164 _freeRangeInFreeLists(false), // No free range at beginning of sweep | |
| 8165 _lastFreeRangeCoalesced(false), | |
| 8166 _freeFinger(g->used_region().start()) | |
| 8167 { | |
| 8168 NOT_PRODUCT( | |
| 8169 _numObjectsFreed = 0; | |
| 8170 _numWordsFreed = 0; | |
| 8171 _numObjectsLive = 0; | |
| 8172 _numWordsLive = 0; | |
| 8173 _numObjectsAlreadyFree = 0; | |
| 8174 _numWordsAlreadyFree = 0; | |
| 8175 _last_fc = NULL; | |
| 8176 | |
| 8177 _sp->initializeIndexedFreeListArrayReturnedBytes(); | |
|
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8178 _sp->dictionary()->initialize_dict_returned_bytes(); |
| 0 | 8179 ) |
| 8180 assert(_limit >= _sp->bottom() && _limit <= _sp->end(), | |
| 8181 "sweep _limit out of bounds"); | |
| 8182 if (CMSTraceSweeper) { | |
|
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8183 gclog_or_tty->print_cr("\n====================\nStarting new sweep with limit " PTR_FORMAT, |
|
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8184 _limit); |
|
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8185 } |
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8186 } |
|
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8187 |
|
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8188 void SweepClosure::print_on(outputStream* st) const { |
|
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|
8189 tty->print_cr("_sp = [" PTR_FORMAT "," PTR_FORMAT ")", |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
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changeset
|
8190 _sp->bottom(), _sp->end()); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8191 tty->print_cr("_limit = " PTR_FORMAT, _limit); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8192 tty->print_cr("_freeFinger = " PTR_FORMAT, _freeFinger); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8193 NOT_PRODUCT(tty->print_cr("_last_fc = " PTR_FORMAT, _last_fc);) |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8194 tty->print_cr("_inFreeRange = %d, _freeRangeInFreeLists = %d, _lastFreeRangeCoalesced = %d", |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8195 _inFreeRange, _freeRangeInFreeLists, _lastFreeRangeCoalesced); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8196 } |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8197 |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8198 #ifndef PRODUCT |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8199 // Assertion checking only: no useful work in product mode -- |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8200 // however, if any of the flags below become product flags, |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8201 // you may need to review this code to see if it needs to be |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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parents:
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changeset
|
8202 // enabled in product mode. |
| 0 | 8203 SweepClosure::~SweepClosure() { |
| 8204 assert_lock_strong(_freelistLock); | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
changeset
|
8205 assert(_limit >= _sp->bottom() && _limit <= _sp->end(), |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
changeset
|
8206 "sweep _limit out of bounds"); |
| 0 | 8207 if (inFreeRange()) { |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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parents:
3356
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changeset
|
8208 warning("inFreeRange() should have been reset; dumping state of SweepClosure"); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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parents:
3356
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changeset
|
8209 print(); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8210 ShouldNotReachHere(); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8211 } |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8212 if (Verbose && PrintGC) { |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8213 gclog_or_tty->print("Collected "SIZE_FORMAT" objects, " SIZE_FORMAT " bytes", |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8214 _numObjectsFreed, _numWordsFreed*sizeof(HeapWord)); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8215 gclog_or_tty->print_cr("\nLive "SIZE_FORMAT" objects, " |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8216 SIZE_FORMAT" bytes " |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8217 "Already free "SIZE_FORMAT" objects, "SIZE_FORMAT" bytes", |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8218 _numObjectsLive, _numWordsLive*sizeof(HeapWord), |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8219 _numObjectsAlreadyFree, _numWordsAlreadyFree*sizeof(HeapWord)); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8220 size_t totalBytes = (_numWordsFreed + _numWordsLive + _numWordsAlreadyFree) |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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parents:
3356
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changeset
|
8221 * sizeof(HeapWord); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8222 gclog_or_tty->print_cr("Total sweep: "SIZE_FORMAT" bytes", totalBytes); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8223 |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
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changeset
|
8224 if (PrintCMSStatistics && CMSVerifyReturnedBytes) { |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8225 size_t indexListReturnedBytes = _sp->sumIndexedFreeListArrayReturnedBytes(); |
|
6028
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
parents:
6026
diff
changeset
|
8226 size_t dict_returned_bytes = _sp->dictionary()->sum_dict_returned_bytes(); |
|
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
parents:
6026
diff
changeset
|
8227 size_t returned_bytes = indexListReturnedBytes + dict_returned_bytes; |
|
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
parents:
6026
diff
changeset
|
8228 gclog_or_tty->print("Returned "SIZE_FORMAT" bytes", returned_bytes); |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8229 gclog_or_tty->print(" Indexed List Returned "SIZE_FORMAT" bytes", |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8230 indexListReturnedBytes); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8231 gclog_or_tty->print_cr(" Dictionary Returned "SIZE_FORMAT" bytes", |
|
6028
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
parents:
6026
diff
changeset
|
8232 dict_returned_bytes); |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
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changeset
|
8233 } |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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parents:
3356
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changeset
|
8234 } |
| 0 | 8235 if (CMSTraceSweeper) { |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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parents:
3356
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changeset
|
8236 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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parents:
3356
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changeset
|
8237 _limit); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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parents:
3356
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changeset
|
8238 } |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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parents:
3356
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changeset
|
8239 } |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8240 #endif // PRODUCT |
| 0 | 8241 |
| 8242 void SweepClosure::initialize_free_range(HeapWord* freeFinger, | |
| 8243 bool freeRangeInFreeLists) { | |
| 8244 if (CMSTraceSweeper) { | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8245 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
ysr
parents:
1994
diff
changeset
|
8246 freeFinger, freeRangeInFreeLists); |
| 0 | 8247 } |
| 8248 assert(!inFreeRange(), "Trampling existing free range"); | |
| 8249 set_inFreeRange(true); | |
| 8250 set_lastFreeRangeCoalesced(false); | |
| 8251 | |
| 8252 set_freeFinger(freeFinger); | |
| 8253 set_freeRangeInFreeLists(freeRangeInFreeLists); | |
| 8254 if (CMSTestInFreeList) { | |
| 8255 if (freeRangeInFreeLists) { | |
| 8256 FreeChunk* fc = (FreeChunk*) freeFinger; | |
|
6028
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
parents:
6026
diff
changeset
|
8257 assert(fc->is_free(), "A chunk on the free list should be free."); |
| 0 | 8258 assert(fc->size() > 0, "Free range should have a size"); |
|
6028
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
parents:
6026
diff
changeset
|
8259 assert(_sp->verify_chunk_in_free_list(fc), "Chunk is not in free lists"); |
| 0 | 8260 } |
| 8261 } | |
| 8262 } | |
| 8263 | |
| 8264 // Note that the sweeper runs concurrently with mutators. Thus, | |
| 8265 // it is possible for direct allocation in this generation to happen | |
| 8266 // in the middle of the sweep. Note that the sweeper also coalesces | |
| 8267 // contiguous free blocks. Thus, unless the sweeper and the allocator | |
| 8268 // synchronize appropriately freshly allocated blocks may get swept up. | |
| 8269 // This is accomplished by the sweeper locking the free lists while | |
| 8270 // it is sweeping. Thus blocks that are determined to be free are | |
| 8271 // indeed free. There is however one additional complication: | |
| 8272 // blocks that have been allocated since the final checkpoint and | |
| 8273 // mark, will not have been marked and so would be treated as | |
| 8274 // unreachable and swept up. To prevent this, the allocator marks | |
| 8275 // the bit map when allocating during the sweep phase. This leads, | |
| 8276 // however, to a further complication -- objects may have been allocated | |
| 8277 // but not yet initialized -- in the sense that the header isn't yet | |
| 8278 // installed. The sweeper can not then determine the size of the block | |
| 8279 // in order to skip over it. To deal with this case, we use a technique | |
| 8280 // (due to Printezis) to encode such uninitialized block sizes in the | |
| 8281 // bit map. Since the bit map uses a bit per every HeapWord, but the | |
| 8282 // CMS generation has a minimum object size of 3 HeapWords, it follows | |
| 8283 // that "normal marks" won't be adjacent in the bit map (there will | |
| 8284 // always be at least two 0 bits between successive 1 bits). We make use | |
| 8285 // of these "unused" bits to represent uninitialized blocks -- the bit | |
| 8286 // corresponding to the start of the uninitialized object and the next | |
| 8287 // bit are both set. Finally, a 1 bit marks the end of the object that | |
| 8288 // started with the two consecutive 1 bits to indicate its potentially | |
| 8289 // uninitialized state. | |
| 8290 | |
| 8291 size_t SweepClosure::do_blk_careful(HeapWord* addr) { | |
| 8292 FreeChunk* fc = (FreeChunk*)addr; | |
| 8293 size_t res; | |
| 8294 | |
|
1720
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
parents:
1716
diff
changeset
|
8295 // 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
parents:
1716
diff
changeset
|
8296 // 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
|
8297 // 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
|
8298 // 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
changeset
|
8299 // 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
ysr
parents:
3356
diff
changeset
|
8300 // 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
parents:
3356
diff
changeset
|
8301 // see the following Zeno-like trail of CRs 6977970, 7008136, 7042740. |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8302 if (addr >= _limit) { // we have swept up to or past the limit: finish up |
| 0 | 8303 assert(_limit >= _sp->bottom() && _limit <= _sp->end(), |
| 8304 "sweep _limit out of bounds"); | |
|
1720
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
parents:
1716
diff
changeset
|
8305 assert(addr < _sp->end(), "addr out of bounds"); |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8306 // Flush any free range we might be holding as a single |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8307 // coalesced chunk to the appropriate free list. |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8308 if (inFreeRange()) { |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8309 assert(freeFinger() >= _sp->bottom() && freeFinger() < _limit, |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8310 err_msg("freeFinger() " PTR_FORMAT" is out-of-bounds", freeFinger())); |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8311 flush_cur_free_chunk(freeFinger(), |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8312 pointer_delta(addr, freeFinger())); |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8313 if (CMSTraceSweeper) { |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8314 gclog_or_tty->print("Sweep: last chunk: "); |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8315 gclog_or_tty->print("put_free_blk 0x%x ("SIZE_FORMAT") " |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8316 "[coalesced:"SIZE_FORMAT"]\n", |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8317 freeFinger(), pointer_delta(addr, freeFinger()), |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8318 lastFreeRangeCoalesced()); |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8319 } |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8320 } |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8321 |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8322 // help the iterator loop finish |
|
1720
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
parents:
1716
diff
changeset
|
8323 return pointer_delta(_sp->end(), addr); |
|
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
parents:
1716
diff
changeset
|
8324 } |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8325 |
|
1720
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
parents:
1716
diff
changeset
|
8326 assert(addr < _limit, "sweep invariant"); |
| 0 | 8327 // check if we should yield |
| 8328 do_yield_check(addr); | |
|
6028
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
parents:
6026
diff
changeset
|
8329 if (fc->is_free()) { |
| 0 | 8330 // Chunk that is already free |
| 8331 res = fc->size(); | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8332 do_already_free_chunk(fc); |
| 0 | 8333 debug_only(_sp->verifyFreeLists()); |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8334 // 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
|
8335 // 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
|
8336 // process of "mangling" the payload of the coalesced block |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8337 // 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
changeset
|
8338 // (erstwhile) header of all the coalesced blocks but the |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8339 // first, so the first disjunct in the assert will not hold |
|
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7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8340 // in that specific case (in which case the second disjunct |
|
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|
8341 // will hold). |
|
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|
8342 assert(res == fc->size() || ((HeapWord*)fc) + res >= _limit, |
|
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|
8343 "Otherwise the size info doesn't change at this step"); |
| 0 | 8344 NOT_PRODUCT( |
| 8345 _numObjectsAlreadyFree++; | |
| 8346 _numWordsAlreadyFree += res; | |
| 8347 ) | |
| 8348 NOT_PRODUCT(_last_fc = fc;) | |
| 8349 } else if (!_bitMap->isMarked(addr)) { | |
| 8350 // Chunk is fresh garbage | |
|
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diff
changeset
|
8351 res = do_garbage_chunk(fc); |
| 0 | 8352 debug_only(_sp->verifyFreeLists()); |
| 8353 NOT_PRODUCT( | |
| 8354 _numObjectsFreed++; | |
| 8355 _numWordsFreed += res; | |
| 8356 ) | |
| 8357 } else { | |
| 8358 // Chunk that is alive. | |
|
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diff
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|
8359 res = do_live_chunk(fc); |
| 0 | 8360 debug_only(_sp->verifyFreeLists()); |
| 8361 NOT_PRODUCT( | |
| 8362 _numObjectsLive++; | |
| 8363 _numWordsLive += res; | |
| 8364 ) | |
| 8365 } | |
| 8366 return res; | |
| 8367 } | |
| 8368 | |
| 8369 // For the smart allocation, record following | |
| 8370 // split deaths - a free chunk is removed from its free list because | |
| 8371 // it is being split into two or more chunks. | |
| 8372 // split birth - a free chunk is being added to its free list because | |
| 8373 // a larger free chunk has been split and resulted in this free chunk. | |
| 8374 // coal death - a free chunk is being removed from its free list because | |
| 8375 // it is being coalesced into a large free chunk. | |
| 8376 // coal birth - a free chunk is being added to its free list because | |
| 8377 // it was created when two or more free chunks where coalesced into | |
| 8378 // this free chunk. | |
| 8379 // | |
| 8380 // These statistics are used to determine the desired number of free | |
| 8381 // chunks of a given size. The desired number is chosen to be relative | |
| 8382 // to the end of a CMS sweep. The desired number at the end of a sweep | |
| 8383 // is the | |
| 8384 // count-at-end-of-previous-sweep (an amount that was enough) | |
| 8385 // - count-at-beginning-of-current-sweep (the excess) | |
| 8386 // + split-births (gains in this size during interval) | |
| 8387 // - split-deaths (demands on this size during interval) | |
| 8388 // where the interval is from the end of one sweep to the end of the | |
| 8389 // next. | |
| 8390 // | |
| 8391 // When sweeping the sweeper maintains an accumulated chunk which is | |
| 8392 // the chunk that is made up of chunks that have been coalesced. That | |
| 8393 // will be termed the left-hand chunk. A new chunk of garbage that | |
| 8394 // is being considered for coalescing will be referred to as the | |
| 8395 // right-hand chunk. | |
| 8396 // | |
| 8397 // When making a decision on whether to coalesce a right-hand chunk with | |
| 8398 // the current left-hand chunk, the current count vs. the desired count | |
| 8399 // of the left-hand chunk is considered. Also if the right-hand chunk | |
| 8400 // is near the large chunk at the end of the heap (see | |
| 8401 // ConcurrentMarkSweepGeneration::isNearLargestChunk()), then the | |
| 8402 // left-hand chunk is coalesced. | |
| 8403 // | |
| 8404 // When making a decision about whether to split a chunk, the desired count | |
| 8405 // vs. the current count of the candidate to be split is also considered. | |
| 8406 // If the candidate is underpopulated (currently fewer chunks than desired) | |
| 8407 // a chunk of an overpopulated (currently more chunks than desired) size may | |
| 8408 // be chosen. The "hint" associated with a free list, if non-null, points | |
| 8409 // to a free list which may be overpopulated. | |
| 8410 // | |
| 8411 | |
|
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|
8412 void SweepClosure::do_already_free_chunk(FreeChunk* fc) { |
|
3746
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|
8413 const size_t size = fc->size(); |
| 0 | 8414 // Chunks that cannot be coalesced are not in the |
| 8415 // free lists. | |
| 8416 if (CMSTestInFreeList && !fc->cantCoalesce()) { | |
|
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|
8417 assert(_sp->verify_chunk_in_free_list(fc), |
| 0 | 8418 "free chunk should be in free lists"); |
| 8419 } | |
| 8420 // a chunk that is already free, should not have been | |
| 8421 // marked in the bit map | |
|
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|
8422 HeapWord* const addr = (HeapWord*) fc; |
| 0 | 8423 assert(!_bitMap->isMarked(addr), "free chunk should be unmarked"); |
| 8424 // Verify that the bit map has no bits marked between | |
| 8425 // addr and purported end of this block. | |
| 8426 _bitMap->verifyNoOneBitsInRange(addr + 1, addr + size); | |
| 8427 | |
|
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|
8428 // Some chunks cannot be coalesced under any circumstances. |
| 0 | 8429 // See the definition of cantCoalesce(). |
| 8430 if (!fc->cantCoalesce()) { | |
| 8431 // This chunk can potentially be coalesced. | |
| 8432 if (_sp->adaptive_freelists()) { | |
| 8433 // All the work is done in | |
|
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|
8434 do_post_free_or_garbage_chunk(fc, size); |
| 0 | 8435 } else { // Not adaptive free lists |
| 8436 // this is a free chunk that can potentially be coalesced by the sweeper; | |
| 8437 if (!inFreeRange()) { | |
| 8438 // if the next chunk is a free block that can't be coalesced | |
| 8439 // it doesn't make sense to remove this chunk from the free lists | |
| 8440 FreeChunk* nextChunk = (FreeChunk*)(addr + size); | |
|
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|
8441 assert((HeapWord*)nextChunk <= _sp->end(), "Chunk size out of bounds?"); |
|
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|
8442 if ((HeapWord*)nextChunk < _sp->end() && // There is another free chunk to the right ... |
|
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|
8443 nextChunk->is_free() && // ... which is free... |
|
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|
8444 nextChunk->cantCoalesce()) { // ... but can't be coalesced |
| 0 | 8445 // nothing to do |
| 8446 } else { | |
| 8447 // Potentially the start of a new free range: | |
| 8448 // Don't eagerly remove it from the free lists. | |
| 8449 // No need to remove it if it will just be put | |
| 8450 // back again. (Also from a pragmatic point of view | |
| 8451 // if it is a free block in a region that is beyond | |
| 8452 // any allocated blocks, an assertion will fail) | |
| 8453 // Remember the start of a free run. | |
| 8454 initialize_free_range(addr, true); | |
| 8455 // end - can coalesce with next chunk | |
| 8456 } | |
| 8457 } else { | |
| 8458 // the midst of a free range, we are coalescing | |
|
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|
8459 print_free_block_coalesced(fc); |
| 0 | 8460 if (CMSTraceSweeper) { |
| 8461 gclog_or_tty->print(" -- pick up free block 0x%x (%d)\n", fc, size); | |
| 8462 } | |
| 8463 // remove it from the free lists | |
| 8464 _sp->removeFreeChunkFromFreeLists(fc); | |
| 8465 set_lastFreeRangeCoalesced(true); | |
| 8466 // If the chunk is being coalesced and the current free range is | |
| 8467 // in the free lists, remove the current free range so that it | |
| 8468 // will be returned to the free lists in its entirety - all | |
| 8469 // the coalesced pieces included. | |
| 8470 if (freeRangeInFreeLists()) { | |
| 8471 FreeChunk* ffc = (FreeChunk*) freeFinger(); | |
| 8472 assert(ffc->size() == pointer_delta(addr, freeFinger()), | |
| 8473 "Size of free range is inconsistent with chunk size."); | |
| 8474 if (CMSTestInFreeList) { | |
|
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|
8475 assert(_sp->verify_chunk_in_free_list(ffc), |
| 0 | 8476 "free range is not in free lists"); |
| 8477 } | |
| 8478 _sp->removeFreeChunkFromFreeLists(ffc); | |
| 8479 set_freeRangeInFreeLists(false); | |
| 8480 } | |
| 8481 } | |
| 8482 } | |
|
3746
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|
8483 // Note that if the chunk is not coalescable (the else arm |
|
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|
8484 // below), we unconditionally flush, without needing to do |
|
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|
8485 // a "lookahead," as we do below. |
|
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|
8486 if (inFreeRange()) lookahead_and_flush(fc, size); |
| 0 | 8487 } else { |
| 8488 // Code path common to both original and adaptive free lists. | |
| 8489 | |
| 8490 // cant coalesce with previous block; this should be treated | |
| 8491 // as the end of a free run if any | |
| 8492 if (inFreeRange()) { | |
| 8493 // we kicked some butt; time to pick up the garbage | |
|
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|
8494 assert(freeFinger() < addr, "freeFinger points too high"); |
|
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1994
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changeset
|
8495 flush_cur_free_chunk(freeFinger(), pointer_delta(addr, freeFinger())); |
| 0 | 8496 } |
| 8497 // else, nothing to do, just continue | |
| 8498 } | |
| 8499 } | |
| 8500 | |
|
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diff
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|
8501 size_t SweepClosure::do_garbage_chunk(FreeChunk* fc) { |
| 0 | 8502 // This is a chunk of garbage. It is not in any free list. |
| 8503 // Add it to a free list or let it possibly be coalesced into | |
| 8504 // a larger chunk. | |
|
3746
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|
8505 HeapWord* const addr = (HeapWord*) fc; |
|
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|
8506 const size_t size = CompactibleFreeListSpace::adjustObjectSize(oop(addr)->size()); |
| 0 | 8507 |
| 8508 if (_sp->adaptive_freelists()) { | |
| 8509 // Verify that the bit map has no bits marked between | |
| 8510 // addr and purported end of just dead object. | |
| 8511 _bitMap->verifyNoOneBitsInRange(addr + 1, addr + size); | |
| 8512 | |
|
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diff
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|
8513 do_post_free_or_garbage_chunk(fc, size); |
| 0 | 8514 } else { |
| 8515 if (!inFreeRange()) { | |
| 8516 // start of a new free range | |
| 8517 assert(size > 0, "A free range should have a size"); | |
| 8518 initialize_free_range(addr, false); | |
| 8519 } else { | |
| 8520 // this will be swept up when we hit the end of the | |
| 8521 // free range | |
| 8522 if (CMSTraceSweeper) { | |
| 8523 gclog_or_tty->print(" -- pick up garbage 0x%x (%d) \n", fc, size); | |
| 8524 } | |
| 8525 // If the chunk is being coalesced and the current free range is | |
| 8526 // in the free lists, remove the current free range so that it | |
| 8527 // will be returned to the free lists in its entirety - all | |
| 8528 // the coalesced pieces included. | |
| 8529 if (freeRangeInFreeLists()) { | |
| 8530 FreeChunk* ffc = (FreeChunk*)freeFinger(); | |
| 8531 assert(ffc->size() == pointer_delta(addr, freeFinger()), | |
| 8532 "Size of free range is inconsistent with chunk size."); | |
| 8533 if (CMSTestInFreeList) { | |
|
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jmasa
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6026
diff
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|
8534 assert(_sp->verify_chunk_in_free_list(ffc), |
| 0 | 8535 "free range is not in free lists"); |
| 8536 } | |
| 8537 _sp->removeFreeChunkFromFreeLists(ffc); | |
| 8538 set_freeRangeInFreeLists(false); | |
| 8539 } | |
| 8540 set_lastFreeRangeCoalesced(true); | |
| 8541 } | |
| 8542 // this will be swept up when we hit the end of the free range | |
| 8543 | |
| 8544 // Verify that the bit map has no bits marked between | |
| 8545 // addr and purported end of just dead object. | |
| 8546 _bitMap->verifyNoOneBitsInRange(addr + 1, addr + size); | |
| 8547 } | |
|
3746
537a4053b0f9
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ysr
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3356
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changeset
|
8548 assert(_limit >= addr + size, |
|
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3356
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|
8549 "A freshly garbage chunk can't possibly straddle over _limit"); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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3356
diff
changeset
|
8550 if (inFreeRange()) lookahead_and_flush(fc, size); |
| 0 | 8551 return size; |
| 8552 } | |
| 8553 | |
|
2132
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diff
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|
8554 size_t SweepClosure::do_live_chunk(FreeChunk* fc) { |
| 0 | 8555 HeapWord* addr = (HeapWord*) fc; |
| 8556 // The sweeper has just found a live object. Return any accumulated | |
| 8557 // left hand chunk to the free lists. | |
| 8558 if (inFreeRange()) { | |
|
2132
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diff
changeset
|
8559 assert(freeFinger() < addr, "freeFinger points too high"); |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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diff
changeset
|
8560 flush_cur_free_chunk(freeFinger(), pointer_delta(addr, freeFinger())); |
|
4947ee68d19c
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diff
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|
8561 } |
|
4947ee68d19c
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diff
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|
8562 |
|
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|
8563 // This object is live: we'd normally expect this to be |
| 0 | 8564 // an oop, and like to assert the following: |
| 8565 // assert(oop(addr)->is_oop(), "live block should be an oop"); | |
| 8566 // However, as we commented above, this may be an object whose | |
| 8567 // header hasn't yet been initialized. | |
| 8568 size_t size; | |
| 8569 assert(_bitMap->isMarked(addr), "Tautology for this control point"); | |
| 8570 if (_bitMap->isMarked(addr + 1)) { | |
| 8571 // Determine the size from the bit map, rather than trying to | |
| 8572 // compute it from the object header. | |
| 8573 HeapWord* nextOneAddr = _bitMap->getNextMarkedWordAddress(addr + 2); | |
| 8574 size = pointer_delta(nextOneAddr + 1, addr); | |
| 8575 assert(size == CompactibleFreeListSpace::adjustObjectSize(size), | |
| 8576 "alignment problem"); | |
| 8577 | |
| 9152 | 8578 #ifdef ASSERT |
|
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|
8579 if (oop(addr)->klass_or_null() != NULL) { |
| 0 | 8580 // Ignore mark word because we are running concurrent with mutators |
| 8581 assert(oop(addr)->is_oop(true), "live block should be an oop"); | |
| 8582 assert(size == | |
| 8583 CompactibleFreeListSpace::adjustObjectSize(oop(addr)->size()), | |
| 8584 "P-mark and computed size do not agree"); | |
| 8585 } | |
|
2132
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diff
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|
8586 #endif |
| 0 | 8587 |
| 8588 } else { | |
| 8589 // This should be an initialized object that's alive. | |
|
6725
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6197
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|
8590 assert(oop(addr)->klass_or_null() != NULL, |
| 0 | 8591 "Should be an initialized object"); |
| 8592 // Ignore mark word because we are running concurrent with mutators | |
| 8593 assert(oop(addr)->is_oop(true), "live block should be an oop"); | |
| 8594 // Verify that the bit map has no bits marked between | |
| 8595 // addr and purported end of this block. | |
| 8596 size = CompactibleFreeListSpace::adjustObjectSize(oop(addr)->size()); | |
| 8597 assert(size >= 3, "Necessary for Printezis marks to work"); | |
| 8598 assert(!_bitMap->isMarked(addr+1), "Tautology for this control point"); | |
| 8599 DEBUG_ONLY(_bitMap->verifyNoOneBitsInRange(addr+2, addr+size);) | |
| 8600 } | |
| 8601 return size; | |
| 8602 } | |
| 8603 | |
|
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diff
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|
8604 void SweepClosure::do_post_free_or_garbage_chunk(FreeChunk* fc, |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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diff
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|
8605 size_t chunkSize) { |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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diff
changeset
|
8606 // do_post_free_or_garbage_chunk() should only be called in the case |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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diff
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|
8607 // of the adaptive free list allocator. |
|
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|
8608 const bool fcInFreeLists = fc->is_free(); |
| 0 | 8609 assert(_sp->adaptive_freelists(), "Should only be used in this case."); |
| 8610 assert((HeapWord*)fc <= _limit, "sweep invariant"); | |
| 8611 if (CMSTestInFreeList && fcInFreeLists) { | |
|
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|
8612 assert(_sp->verify_chunk_in_free_list(fc), "free chunk is not in free lists"); |
|
2132
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|
8613 } |
| 0 | 8614 |
| 8615 if (CMSTraceSweeper) { | |
| 8616 gclog_or_tty->print_cr(" -- pick up another chunk at 0x%x (%d)", fc, chunkSize); | |
| 8617 } | |
| 8618 | |
|
3746
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|
8619 HeapWord* const fc_addr = (HeapWord*) fc; |
| 0 | 8620 |
| 8621 bool coalesce; | |
|
3746
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ysr
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3356
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|
8622 const size_t left = pointer_delta(fc_addr, freeFinger()); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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changeset
|
8623 const size_t right = chunkSize; |
| 0 | 8624 switch (FLSCoalescePolicy) { |
| 8625 // numeric value forms a coalition aggressiveness metric | |
| 8626 case 0: { // never coalesce | |
| 8627 coalesce = false; | |
| 8628 break; | |
| 8629 } | |
| 8630 case 1: { // coalesce if left & right chunks on overpopulated lists | |
| 8631 coalesce = _sp->coalOverPopulated(left) && | |
| 8632 _sp->coalOverPopulated(right); | |
| 8633 break; | |
| 8634 } | |
| 8635 case 2: { // coalesce if left chunk on overpopulated list (default) | |
| 8636 coalesce = _sp->coalOverPopulated(left); | |
| 8637 break; | |
| 8638 } | |
| 8639 case 3: { // coalesce if left OR right chunk on overpopulated list | |
| 8640 coalesce = _sp->coalOverPopulated(left) || | |
| 8641 _sp->coalOverPopulated(right); | |
| 8642 break; | |
| 8643 } | |
| 8644 case 4: { // always coalesce | |
| 8645 coalesce = true; | |
| 8646 break; | |
| 8647 } | |
| 8648 default: | |
| 8649 ShouldNotReachHere(); | |
| 8650 } | |
| 8651 | |
| 8652 // Should the current free range be coalesced? | |
| 8653 // If the chunk is in a free range and either we decided to coalesce above | |
| 8654 // or the chunk is near the large block at the end of the heap | |
| 8655 // (isNearLargestChunk() returns true), then coalesce this chunk. | |
|
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|
8656 const bool doCoalesce = inFreeRange() |
|
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changeset
|
8657 && (coalesce || _g->isNearLargestChunk(fc_addr)); |
| 0 | 8658 if (doCoalesce) { |
| 8659 // Coalesce the current free range on the left with the new | |
| 8660 // chunk on the right. If either is on a free list, | |
| 8661 // it must be removed from the list and stashed in the closure. | |
| 8662 if (freeRangeInFreeLists()) { | |
|
3746
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|
8663 FreeChunk* const ffc = (FreeChunk*)freeFinger(); |
|
537a4053b0f9
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changeset
|
8664 assert(ffc->size() == pointer_delta(fc_addr, freeFinger()), |
| 0 | 8665 "Size of free range is inconsistent with chunk size."); |
| 8666 if (CMSTestInFreeList) { | |
|
6028
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7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
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diff
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|
8667 assert(_sp->verify_chunk_in_free_list(ffc), |
| 0 | 8668 "Chunk is not in free lists"); |
| 8669 } | |
| 8670 _sp->coalDeath(ffc->size()); | |
| 8671 _sp->removeFreeChunkFromFreeLists(ffc); | |
| 8672 set_freeRangeInFreeLists(false); | |
| 8673 } | |
| 8674 if (fcInFreeLists) { | |
| 8675 _sp->coalDeath(chunkSize); | |
| 8676 assert(fc->size() == chunkSize, | |
| 8677 "The chunk has the wrong size or is not in the free lists"); | |
| 8678 _sp->removeFreeChunkFromFreeLists(fc); | |
| 8679 } | |
| 8680 set_lastFreeRangeCoalesced(true); | |
|
3746
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changeset
|
8681 print_free_block_coalesced(fc); |
| 0 | 8682 } else { // not in a free range and/or should not coalesce |
| 8683 // Return the current free range and start a new one. | |
| 8684 if (inFreeRange()) { | |
| 8685 // In a free range but cannot coalesce with the right hand chunk. | |
| 8686 // Put the current free range into the free lists. | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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diff
changeset
|
8687 flush_cur_free_chunk(freeFinger(), |
|
3746
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changeset
|
8688 pointer_delta(fc_addr, freeFinger())); |
| 0 | 8689 } |
| 8690 // Set up for new free range. Pass along whether the right hand | |
| 8691 // chunk is in the free lists. | |
| 8692 initialize_free_range((HeapWord*)fc, fcInFreeLists); | |
| 8693 } | |
| 8694 } | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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diff
changeset
|
8695 |
|
3746
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|
8696 // Lookahead flush: |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8697 // 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
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|
8698 // 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
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parents:
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|
8699 // 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
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parents:
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|
8700 // this can be the case only for an already free or freshly garbage |
|
537a4053b0f9
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changeset
|
8701 // chunk. If this block is an object, it can never straddle |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8702 // over _limit. The "straddling" occurs when _limit is set at |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8703 // the previous end of the space when this cycle started, and |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8704 // a subsequent heap expansion caused the previously co-terminal |
|
537a4053b0f9
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changeset
|
8705 // free block to be coalesced with the newly expanded portion, |
|
537a4053b0f9
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|
8706 // thus rendering _limit a non-block-boundary making it dangerous |
|
537a4053b0f9
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|
8707 // for the sweeper to step over and examine. |
|
537a4053b0f9
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3356
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changeset
|
8708 void SweepClosure::lookahead_and_flush(FreeChunk* fc, size_t chunk_size) { |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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parents:
3356
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|
8709 assert(inFreeRange(), "Should only be called if currently in a free range."); |
|
537a4053b0f9
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|
8710 HeapWord* const eob = ((HeapWord*)fc) + chunk_size; |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8711 assert(_sp->used_region().contains(eob - 1), |
|
12112
1bb10d3170fa
8022817: CMS should not shrink if compaction was not done
jmasa
parents:
12088
diff
changeset
|
8712 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
|
8713 " out of bounds wrt _sp = [" PTR_FORMAT "," PTR_FORMAT ")" |
|
3746
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parents:
3356
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|
8714 " when examining fc = " PTR_FORMAT "(" SIZE_FORMAT ")", |
|
12112
1bb10d3170fa
8022817: CMS should not shrink if compaction was not done
jmasa
parents:
12088
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changeset
|
8715 eob, eob-1, _limit, _sp->bottom(), _sp->end(), fc, chunk_size)); |
|
3746
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changeset
|
8716 if (eob >= _limit) { |
|
6028
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7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
parents:
6026
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|
8717 assert(eob == _limit || fc->is_free(), "Only a free chunk should allow us to cross over the limit"); |
|
3746
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parents:
3356
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|
8718 if (CMSTraceSweeper) { |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8719 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
ysr
parents:
3356
diff
changeset
|
8720 "[" PTR_FORMAT "," PTR_FORMAT ") in space " |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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3356
diff
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|
8721 "[" PTR_FORMAT "," PTR_FORMAT ")", |
|
537a4053b0f9
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ysr
parents:
3356
diff
changeset
|
8722 _limit, fc, eob, _sp->bottom(), _sp->end()); |
|
537a4053b0f9
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|
8723 } |
|
537a4053b0f9
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3356
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changeset
|
8724 // Return the storage we are tracking back into the free lists. |
|
537a4053b0f9
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3356
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changeset
|
8725 if (CMSTraceSweeper) { |
|
537a4053b0f9
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parents:
3356
diff
changeset
|
8726 gclog_or_tty->print_cr("Flushing ... "); |
|
537a4053b0f9
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3356
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|
8727 } |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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3356
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changeset
|
8728 assert(freeFinger() < eob, "Error"); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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parents:
3356
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|
8729 flush_cur_free_chunk( freeFinger(), pointer_delta(eob, freeFinger())); |
|
537a4053b0f9
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|
8730 } |
|
537a4053b0f9
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3356
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|
8731 } |
|
537a4053b0f9
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3356
diff
changeset
|
8732 |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8733 void SweepClosure::flush_cur_free_chunk(HeapWord* chunk, size_t size) { |
| 0 | 8734 assert(inFreeRange(), "Should only be called if currently in a free range."); |
| 8735 assert(size > 0, | |
| 8736 "A zero sized chunk cannot be added to the free lists."); | |
| 8737 if (!freeRangeInFreeLists()) { | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
changeset
|
8738 if (CMSTestInFreeList) { |
| 0 | 8739 FreeChunk* fc = (FreeChunk*) chunk; |
|
6028
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7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
parents:
6026
diff
changeset
|
8740 fc->set_size(size); |
|
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
parents:
6026
diff
changeset
|
8741 assert(!_sp->verify_chunk_in_free_list(fc), |
| 0 | 8742 "chunk should not be in free lists yet"); |
| 8743 } | |
| 8744 if (CMSTraceSweeper) { | |
| 8745 gclog_or_tty->print_cr(" -- add free block 0x%x (%d) to free lists", | |
| 8746 chunk, size); | |
| 8747 } | |
| 8748 // A new free range is going to be starting. The current | |
| 8749 // free range has not been added to the free lists yet or | |
| 8750 // was removed so add it back. | |
| 8751 // If the current free range was coalesced, then the death | |
| 8752 // of the free range was recorded. Record a birth now. | |
| 8753 if (lastFreeRangeCoalesced()) { | |
| 8754 _sp->coalBirth(size); | |
| 8755 } | |
| 8756 _sp->addChunkAndRepairOffsetTable(chunk, size, | |
| 8757 lastFreeRangeCoalesced()); | |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8758 } else if (CMSTraceSweeper) { |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8759 gclog_or_tty->print_cr("Already in free list: nothing to flush"); |
| 0 | 8760 } |
| 8761 set_inFreeRange(false); | |
| 8762 set_freeRangeInFreeLists(false); | |
| 8763 } | |
| 8764 | |
| 8765 // We take a break if we've been at this for a while, | |
| 8766 // so as to avoid monopolizing the locks involved. | |
| 8767 void SweepClosure::do_yield_work(HeapWord* addr) { | |
| 8768 // Return current free chunk being used for coalescing (if any) | |
| 8769 // to the appropriate freelist. After yielding, the next | |
| 8770 // free block encountered will start a coalescing range of | |
| 8771 // free blocks. If the next free block is adjacent to the | |
| 8772 // chunk just flushed, they will need to wait for the next | |
| 8773 // sweep to be coalesced. | |
| 8774 if (inFreeRange()) { | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8775 flush_cur_free_chunk(freeFinger(), pointer_delta(addr, freeFinger())); |
| 0 | 8776 } |
| 8777 | |
| 8778 // First give up the locks, then yield, then re-lock. | |
| 8779 // We should probably use a constructor/destructor idiom to | |
| 8780 // do this unlock/lock or modify the MutexUnlocker class to | |
| 8781 // serve our purpose. XXX | |
| 8782 assert_lock_strong(_bitMap->lock()); | |
| 8783 assert_lock_strong(_freelistLock); | |
| 8784 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 8785 "CMS thread should hold CMS token"); | |
| 8786 _bitMap->lock()->unlock(); | |
| 8787 _freelistLock->unlock(); | |
| 8788 ConcurrentMarkSweepThread::desynchronize(true); | |
| 8789 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 8790 _collector->stopTimer(); | |
| 8791 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 8792 if (PrintCMSStatistics != 0) { | |
| 8793 _collector->incrementYields(); | |
| 8794 } | |
| 8795 _collector->icms_wait(); | |
| 8796 | |
| 8797 // See the comment in coordinator_yield() | |
| 8798 for (unsigned i = 0; i < CMSYieldSleepCount && | |
| 8799 ConcurrentMarkSweepThread::should_yield() && | |
| 8800 !CMSCollector::foregroundGCIsActive(); ++i) { | |
| 8801 os::sleep(Thread::current(), 1, false); | |
| 8802 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 8803 } | |
| 8804 | |
| 8805 ConcurrentMarkSweepThread::synchronize(true); | |
| 8806 _freelistLock->lock(); | |
| 8807 _bitMap->lock()->lock_without_safepoint_check(); | |
| 8808 _collector->startTimer(); | |
| 8809 } | |
| 8810 | |
| 8811 #ifndef PRODUCT | |
| 8812 // This is actually very useful in a product build if it can | |
| 8813 // be called from the debugger. Compile it into the product | |
| 8814 // as needed. | |
|
6028
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6026
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|
8815 bool debug_verify_chunk_in_free_list(FreeChunk* fc) { |
|
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
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6026
diff
changeset
|
8816 return debug_cms_space->verify_chunk_in_free_list(fc); |
| 0 | 8817 } |
|
3746
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7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
diff
changeset
|
8818 #endif |
|
537a4053b0f9
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3356
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changeset
|
8819 |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8820 void SweepClosure::print_free_block_coalesced(FreeChunk* fc) const { |
| 0 | 8821 if (CMSTraceSweeper) { |
|
3746
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7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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3356
diff
changeset
|
8822 gclog_or_tty->print_cr("Sweep:coal_free_blk " PTR_FORMAT " (" SIZE_FORMAT ")", |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8823 fc, fc->size()); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
diff
changeset
|
8824 } |
|
537a4053b0f9
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ysr
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3356
diff
changeset
|
8825 } |
| 0 | 8826 |
| 8827 // CMSIsAliveClosure | |
| 8828 bool CMSIsAliveClosure::do_object_b(oop obj) { | |
| 8829 HeapWord* addr = (HeapWord*)obj; | |
| 8830 return addr != NULL && | |
| 8831 (!_span.contains(addr) || _bit_map->isMarked(addr)); | |
| 8832 } | |
| 8833 | |
|
6725
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
8834 |
| 935 | 8835 CMSKeepAliveClosure::CMSKeepAliveClosure( CMSCollector* collector, |
| 8836 MemRegion span, | |
| 8837 CMSBitMap* bit_map, CMSMarkStack* mark_stack, | |
|
6725
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
8838 bool cpc): |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
8839 _collector(collector), |
| 935 | 8840 _span(span), |
| 8841 _bit_map(bit_map), | |
| 8842 _mark_stack(mark_stack), | |
| 8843 _concurrent_precleaning(cpc) { | |
| 8844 assert(!_span.is_empty(), "Empty span could spell trouble"); | |
| 8845 } | |
| 8846 | |
| 8847 | |
| 0 | 8848 // CMSKeepAliveClosure: the serial version |
|
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
8849 void CMSKeepAliveClosure::do_oop(oop obj) { |
|
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
8850 HeapWord* addr = (HeapWord*)obj; |
| 0 | 8851 if (_span.contains(addr) && |
| 8852 !_bit_map->isMarked(addr)) { | |
| 8853 _bit_map->mark(addr); | |
| 8854 bool simulate_overflow = false; | |
| 8855 NOT_PRODUCT( | |
| 8856 if (CMSMarkStackOverflowALot && | |
| 8857 _collector->simulate_overflow()) { | |
| 8858 // simulate a stack overflow | |
| 8859 simulate_overflow = true; | |
| 8860 } | |
| 8861 ) | |
|
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8862 if (simulate_overflow || !_mark_stack->push(obj)) { |
|
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8863 if (_concurrent_precleaning) { |
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8864 // We dirty the overflown object and let the remark |
|
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8865 // phase deal with it. |
|
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8866 assert(_collector->overflow_list_is_empty(), "Error"); |
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8867 // In the case of object arrays, we need to dirty all of |
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8868 // the cards that the object spans. No locking or atomics |
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8869 // are needed since no one else can be mutating the mod union |
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8870 // table. |
|
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8871 if (obj->is_objArray()) { |
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8872 size_t sz = obj->size(); |
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8873 HeapWord* end_card_addr = |
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8874 (HeapWord*)round_to((intptr_t)(addr+sz), CardTableModRefBS::card_size); |
|
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8875 MemRegion redirty_range = MemRegion(addr, end_card_addr); |
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8876 assert(!redirty_range.is_empty(), "Arithmetical tautology"); |
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8877 _collector->_modUnionTable.mark_range(redirty_range); |
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8878 } else { |
|
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8879 _collector->_modUnionTable.mark(addr); |
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8880 } |
|
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8881 _collector->_ser_kac_preclean_ovflw++; |
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8882 } else { |
|
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8883 _collector->push_on_overflow_list(obj); |
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8884 _collector->_ser_kac_ovflw++; |
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8885 } |
| 0 | 8886 } |
| 8887 } | |
| 8888 } | |
| 8889 | |
|
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8890 void CMSKeepAliveClosure::do_oop(oop* p) { CMSKeepAliveClosure::do_oop_work(p); } |
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8891 void CMSKeepAliveClosure::do_oop(narrowOop* p) { CMSKeepAliveClosure::do_oop_work(p); } |
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8892 |
| 0 | 8893 // CMSParKeepAliveClosure: a parallel version of the above. |
| 8894 // The work queues are private to each closure (thread), | |
| 8895 // but (may be) available for stealing by other threads. | |
|
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8896 void CMSParKeepAliveClosure::do_oop(oop obj) { |
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8897 HeapWord* addr = (HeapWord*)obj; |
| 0 | 8898 if (_span.contains(addr) && |
| 8899 !_bit_map->isMarked(addr)) { | |
| 8900 // In general, during recursive tracing, several threads | |
| 8901 // may be concurrently getting here; the first one to | |
| 8902 // "tag" it, claims it. | |
| 8903 if (_bit_map->par_mark(addr)) { | |
|
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8904 bool res = _work_queue->push(obj); |
| 0 | 8905 assert(res, "Low water mark should be much less than capacity"); |
| 8906 // Do a recursive trim in the hope that this will keep | |
| 8907 // stack usage lower, but leave some oops for potential stealers | |
| 8908 trim_queue(_low_water_mark); | |
| 8909 } // Else, another thread got there first | |
| 8910 } | |
| 8911 } | |
| 8912 | |
|
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8913 void CMSParKeepAliveClosure::do_oop(oop* p) { CMSParKeepAliveClosure::do_oop_work(p); } |
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8914 void CMSParKeepAliveClosure::do_oop(narrowOop* p) { CMSParKeepAliveClosure::do_oop_work(p); } |
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8915 |
| 0 | 8916 void CMSParKeepAliveClosure::trim_queue(uint max) { |
| 8917 while (_work_queue->size() > max) { | |
| 8918 oop new_oop; | |
| 8919 if (_work_queue->pop_local(new_oop)) { | |
| 8920 assert(new_oop != NULL && new_oop->is_oop(), "Expected an oop"); | |
| 8921 assert(_bit_map->isMarked((HeapWord*)new_oop), | |
| 8922 "no white objects on this stack!"); | |
| 8923 assert(_span.contains((HeapWord*)new_oop), "Out of bounds oop"); | |
| 8924 // iterate over the oops in this oop, marking and pushing | |
| 8925 // the ones in CMS heap (i.e. in _span). | |
| 8926 new_oop->oop_iterate(&_mark_and_push); | |
| 8927 } | |
| 8928 } | |
| 8929 } | |
| 8930 | |
| 935 | 8931 CMSInnerParMarkAndPushClosure::CMSInnerParMarkAndPushClosure( |
| 8932 CMSCollector* collector, | |
| 8933 MemRegion span, CMSBitMap* bit_map, | |
| 8934 OopTaskQueue* work_queue): | |
|
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8935 _collector(collector), |
| 935 | 8936 _span(span), |
| 8937 _bit_map(bit_map), | |
| 8938 _work_queue(work_queue) { } | |
| 8939 | |
|
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8940 void CMSInnerParMarkAndPushClosure::do_oop(oop obj) { |
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8941 HeapWord* addr = (HeapWord*)obj; |
| 0 | 8942 if (_span.contains(addr) && |
| 8943 !_bit_map->isMarked(addr)) { | |
| 8944 if (_bit_map->par_mark(addr)) { | |
| 8945 bool simulate_overflow = false; | |
| 8946 NOT_PRODUCT( | |
| 8947 if (CMSMarkStackOverflowALot && | |
| 8948 _collector->par_simulate_overflow()) { | |
| 8949 // simulate a stack overflow | |
| 8950 simulate_overflow = true; | |
| 8951 } | |
| 8952 ) | |
|
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8953 if (simulate_overflow || !_work_queue->push(obj)) { |
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8954 _collector->par_push_on_overflow_list(obj); |
| 0 | 8955 _collector->_par_kac_ovflw++; |
| 8956 } | |
| 8957 } // Else another thread got there already | |
| 8958 } | |
| 8959 } | |
| 8960 | |
|
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8961 void CMSInnerParMarkAndPushClosure::do_oop(oop* p) { CMSInnerParMarkAndPushClosure::do_oop_work(p); } |
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8962 void CMSInnerParMarkAndPushClosure::do_oop(narrowOop* p) { CMSInnerParMarkAndPushClosure::do_oop_work(p); } |
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8963 |
| 0 | 8964 ////////////////////////////////////////////////////////////////// |
| 8965 // CMSExpansionCause ///////////////////////////// | |
| 8966 ////////////////////////////////////////////////////////////////// | |
| 8967 const char* CMSExpansionCause::to_string(CMSExpansionCause::Cause cause) { | |
| 8968 switch (cause) { | |
| 8969 case _no_expansion: | |
| 8970 return "No expansion"; | |
| 8971 case _satisfy_free_ratio: | |
| 8972 return "Free ratio"; | |
| 8973 case _satisfy_promotion: | |
| 8974 return "Satisfy promotion"; | |
| 8975 case _satisfy_allocation: | |
| 8976 return "allocation"; | |
| 8977 case _allocate_par_lab: | |
| 8978 return "Par LAB"; | |
| 8979 case _allocate_par_spooling_space: | |
| 8980 return "Par Spooling Space"; | |
| 8981 case _adaptive_size_policy: | |
| 8982 return "Ergonomics"; | |
| 8983 default: | |
| 8984 return "unknown"; | |
| 8985 } | |
| 8986 } | |
| 8987 | |
| 8988 void CMSDrainMarkingStackClosure::do_void() { | |
| 8989 // the max number to take from overflow list at a time | |
| 8990 const size_t num = _mark_stack->capacity()/4; | |
|
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8991 assert(!_concurrent_precleaning || _collector->overflow_list_is_empty(), |
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8992 "Overflow list should be NULL during concurrent phases"); |
| 0 | 8993 while (!_mark_stack->isEmpty() || |
| 8994 // if stack is empty, check the overflow list | |
| 8995 _collector->take_from_overflow_list(num, _mark_stack)) { | |
|
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8996 oop obj = _mark_stack->pop(); |
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8997 HeapWord* addr = (HeapWord*)obj; |
| 0 | 8998 assert(_span.contains(addr), "Should be within span"); |
| 8999 assert(_bit_map->isMarked(addr), "Should be marked"); | |
|
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9000 assert(obj->is_oop(), "Should be an oop"); |
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9001 obj->oop_iterate(_keep_alive); |
| 0 | 9002 } |
| 9003 } | |
| 9004 | |
| 9005 void CMSParDrainMarkingStackClosure::do_void() { | |
| 9006 // drain queue | |
| 9007 trim_queue(0); | |
| 9008 } | |
| 9009 | |
| 9010 // Trim our work_queue so its length is below max at return | |
| 9011 void CMSParDrainMarkingStackClosure::trim_queue(uint max) { | |
| 9012 while (_work_queue->size() > max) { | |
| 9013 oop new_oop; | |
| 9014 if (_work_queue->pop_local(new_oop)) { | |
| 9015 assert(new_oop->is_oop(), "Expected an oop"); | |
| 9016 assert(_bit_map->isMarked((HeapWord*)new_oop), | |
| 9017 "no white objects on this stack!"); | |
| 9018 assert(_span.contains((HeapWord*)new_oop), "Out of bounds oop"); | |
| 9019 // iterate over the oops in this oop, marking and pushing | |
| 9020 // the ones in CMS heap (i.e. in _span). | |
| 9021 new_oop->oop_iterate(&_mark_and_push); | |
| 9022 } | |
| 9023 } | |
| 9024 } | |
| 9025 | |
| 9026 //////////////////////////////////////////////////////////////////// | |
| 9027 // Support for Marking Stack Overflow list handling and related code | |
| 9028 //////////////////////////////////////////////////////////////////// | |
| 9029 // Much of the following code is similar in shape and spirit to the | |
| 9030 // code used in ParNewGC. We should try and share that code | |
| 9031 // as much as possible in the future. | |
| 9032 | |
| 9033 #ifndef PRODUCT | |
| 9034 // Debugging support for CMSStackOverflowALot | |
| 9035 | |
| 9036 // It's OK to call this multi-threaded; the worst thing | |
| 9037 // that can happen is that we'll get a bunch of closely | |
| 9038 // spaced simulated oveflows, but that's OK, in fact | |
| 9039 // probably good as it would exercise the overflow code | |
| 9040 // under contention. | |
| 9041 bool CMSCollector::simulate_overflow() { | |
| 9042 if (_overflow_counter-- <= 0) { // just being defensive | |
| 9043 _overflow_counter = CMSMarkStackOverflowInterval; | |
| 9044 return true; | |
| 9045 } else { | |
| 9046 return false; | |
| 9047 } | |
| 9048 } | |
| 9049 | |
| 9050 bool CMSCollector::par_simulate_overflow() { | |
| 9051 return simulate_overflow(); | |
| 9052 } | |
| 9053 #endif | |
| 9054 | |
| 9055 // Single-threaded | |
| 9056 bool CMSCollector::take_from_overflow_list(size_t num, CMSMarkStack* stack) { | |
| 9057 assert(stack->isEmpty(), "Expected precondition"); | |
| 9058 assert(stack->capacity() > num, "Shouldn't bite more than can chew"); | |
| 9059 size_t i = num; | |
| 9060 oop cur = _overflow_list; | |
| 9061 const markOop proto = markOopDesc::prototype(); | |
| 534 | 9062 NOT_PRODUCT(ssize_t n = 0;) |
| 0 | 9063 for (oop next; i > 0 && cur != NULL; cur = next, i--) { |
| 9064 next = oop(cur->mark()); | |
| 9065 cur->set_mark(proto); // until proven otherwise | |
| 9066 assert(cur->is_oop(), "Should be an oop"); | |
| 9067 bool res = stack->push(cur); | |
| 9068 assert(res, "Bit off more than can chew?"); | |
| 9069 NOT_PRODUCT(n++;) | |
| 9070 } | |
| 9071 _overflow_list = cur; | |
| 9072 #ifndef PRODUCT | |
| 9073 assert(_num_par_pushes >= n, "Too many pops?"); | |
| 9074 _num_par_pushes -=n; | |
| 9075 #endif | |
| 9076 return !stack->isEmpty(); | |
| 9077 } | |
| 9078 | |
|
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9079 #define BUSY (cast_to_oop<intptr_t>(0x1aff1aff)) |
| 534 | 9080 // (MT-safe) Get a prefix of at most "num" from the list. |
| 9081 // The overflow list is chained through the mark word of | |
| 9082 // each object in the list. We fetch the entire list, | |
| 9083 // break off a prefix of the right size and return the | |
| 9084 // remainder. If other threads try to take objects from | |
| 9085 // the overflow list at that time, they will wait for | |
| 9086 // some time to see if data becomes available. If (and | |
| 9087 // only if) another thread places one or more object(s) | |
| 9088 // on the global list before we have returned the suffix | |
| 9089 // to the global list, we will walk down our local list | |
| 9090 // to find its end and append the global list to | |
| 9091 // our suffix before returning it. This suffix walk can | |
| 9092 // prove to be expensive (quadratic in the amount of traffic) | |
| 9093 // when there are many objects in the overflow list and | |
| 9094 // there is much producer-consumer contention on the list. | |
| 9095 // *NOTE*: The overflow list manipulation code here and | |
| 9096 // in ParNewGeneration:: are very similar in shape, | |
| 9097 // except that in the ParNew case we use the old (from/eden) | |
| 9098 // copy of the object to thread the list via its klass word. | |
| 9099 // Because of the common code, if you make any changes in | |
| 9100 // the code below, please check the ParNew version to see if | |
| 9101 // similar changes might be needed. | |
| 9102 // CR 6797058 has been filed to consolidate the common code. | |
| 0 | 9103 bool CMSCollector::par_take_from_overflow_list(size_t num, |
|
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9104 OopTaskQueue* work_q, |
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9105 int no_of_gc_threads) { |
| 534 | 9106 assert(work_q->size() == 0, "First empty local work queue"); |
| 0 | 9107 assert(num < work_q->max_elems(), "Can't bite more than we can chew"); |
| 9108 if (_overflow_list == NULL) { | |
| 9109 return false; | |
| 9110 } | |
| 9111 // Grab the entire list; we'll put back a suffix | |
|
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9112 oop prefix = cast_to_oop(Atomic::xchg_ptr(BUSY, &_overflow_list)); |
| 534 | 9113 Thread* tid = Thread::current(); |
|
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9114 // Before "no_of_gc_threads" was introduced CMSOverflowSpinCount was |
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9115 // set to ParallelGCThreads. |
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9116 size_t CMSOverflowSpinCount = (size_t) no_of_gc_threads; // was ParallelGCThreads; |
| 534 | 9117 size_t sleep_time_millis = MAX2((size_t)1, num/100); |
| 9118 // If the list is busy, we spin for a short while, | |
| 9119 // sleeping between attempts to get the list. | |
| 9120 for (size_t spin = 0; prefix == BUSY && spin < CMSOverflowSpinCount; spin++) { | |
| 9121 os::sleep(tid, sleep_time_millis, false); | |
| 9122 if (_overflow_list == NULL) { | |
| 9123 // Nothing left to take | |
| 9124 return false; | |
| 9125 } else if (_overflow_list != BUSY) { | |
| 9126 // Try and grab the prefix | |
|
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9127 prefix = cast_to_oop(Atomic::xchg_ptr(BUSY, &_overflow_list)); |
| 534 | 9128 } |
| 9129 } | |
| 9130 // If the list was found to be empty, or we spun long | |
| 9131 // enough, we give up and return empty-handed. If we leave | |
| 9132 // the list in the BUSY state below, it must be the case that | |
| 9133 // some other thread holds the overflow list and will set it | |
| 9134 // to a non-BUSY state in the future. | |
| 9135 if (prefix == NULL || prefix == BUSY) { | |
| 9136 // Nothing to take or waited long enough | |
| 9137 if (prefix == NULL) { | |
| 9138 // Write back the NULL in case we overwrote it with BUSY above | |
| 9139 // and it is still the same value. | |
| 9140 (void) Atomic::cmpxchg_ptr(NULL, &_overflow_list, BUSY); | |
| 9141 } | |
| 9142 return false; | |
| 9143 } | |
| 9144 assert(prefix != NULL && prefix != BUSY, "Error"); | |
| 0 | 9145 size_t i = num; |
| 9146 oop cur = prefix; | |
| 534 | 9147 // Walk down the first "num" objects, unless we reach the end. |
| 0 | 9148 for (; i > 1 && cur->mark() != NULL; cur = oop(cur->mark()), i--); |
| 534 | 9149 if (cur->mark() == NULL) { |
| 9150 // We have "num" or fewer elements in the list, so there | |
| 9151 // is nothing to return to the global list. | |
| 9152 // Write back the NULL in lieu of the BUSY we wrote | |
| 9153 // above, if it is still the same value. | |
| 9154 if (_overflow_list == BUSY) { | |
| 9155 (void) Atomic::cmpxchg_ptr(NULL, &_overflow_list, BUSY); | |
| 9156 } | |
| 9157 } else { | |
| 9158 // Chop off the suffix and rerturn it to the global list. | |
| 9159 assert(cur->mark() != BUSY, "Error"); | |
| 0 | 9160 oop suffix_head = cur->mark(); // suffix will be put back on global list |
| 9161 cur->set_mark(NULL); // break off suffix | |
| 534 | 9162 // It's possible that the list is still in the empty(busy) state |
| 9163 // we left it in a short while ago; in that case we may be | |
| 9164 // able to place back the suffix without incurring the cost | |
| 9165 // of a walk down the list. | |
| 0 | 9166 oop observed_overflow_list = _overflow_list; |
| 534 | 9167 oop cur_overflow_list = observed_overflow_list; |
| 9168 bool attached = false; | |
| 9169 while (observed_overflow_list == BUSY || observed_overflow_list == NULL) { | |
| 0 | 9170 observed_overflow_list = |
| 534 | 9171 (oop) Atomic::cmpxchg_ptr(suffix_head, &_overflow_list, cur_overflow_list); |
| 9172 if (cur_overflow_list == observed_overflow_list) { | |
| 9173 attached = true; | |
| 9174 break; | |
| 9175 } else cur_overflow_list = observed_overflow_list; | |
| 9176 } | |
| 9177 if (!attached) { | |
| 9178 // Too bad, someone else sneaked in (at least) an element; we'll need | |
| 9179 // to do a splice. Find tail of suffix so we can prepend suffix to global | |
| 9180 // list. | |
| 9181 for (cur = suffix_head; cur->mark() != NULL; cur = (oop)(cur->mark())); | |
| 9182 oop suffix_tail = cur; | |
| 9183 assert(suffix_tail != NULL && suffix_tail->mark() == NULL, | |
| 9184 "Tautology"); | |
| 9185 observed_overflow_list = _overflow_list; | |
| 9186 do { | |
| 9187 cur_overflow_list = observed_overflow_list; | |
| 9188 if (cur_overflow_list != BUSY) { | |
| 9189 // Do the splice ... | |
| 9190 suffix_tail->set_mark(markOop(cur_overflow_list)); | |
| 9191 } else { // cur_overflow_list == BUSY | |
| 9192 suffix_tail->set_mark(NULL); | |
| 9193 } | |
| 9194 // ... and try to place spliced list back on overflow_list ... | |
| 9195 observed_overflow_list = | |
| 9196 (oop) Atomic::cmpxchg_ptr(suffix_head, &_overflow_list, cur_overflow_list); | |
| 9197 } while (cur_overflow_list != observed_overflow_list); | |
| 9198 // ... until we have succeeded in doing so. | |
| 9199 } | |
| 0 | 9200 } |
| 9201 | |
| 9202 // Push the prefix elements on work_q | |
| 9203 assert(prefix != NULL, "control point invariant"); | |
| 9204 const markOop proto = markOopDesc::prototype(); | |
| 9205 oop next; | |
| 534 | 9206 NOT_PRODUCT(ssize_t n = 0;) |
| 0 | 9207 for (cur = prefix; cur != NULL; cur = next) { |
| 9208 next = oop(cur->mark()); | |
| 9209 cur->set_mark(proto); // until proven otherwise | |
| 9210 assert(cur->is_oop(), "Should be an oop"); | |
| 9211 bool res = work_q->push(cur); | |
| 9212 assert(res, "Bit off more than we can chew?"); | |
| 9213 NOT_PRODUCT(n++;) | |
| 9214 } | |
| 9215 #ifndef PRODUCT | |
| 9216 assert(_num_par_pushes >= n, "Too many pops?"); | |
| 9217 Atomic::add_ptr(-(intptr_t)n, &_num_par_pushes); | |
| 9218 #endif | |
| 9219 return true; | |
| 9220 } | |
| 9221 | |
| 9222 // Single-threaded | |
| 9223 void CMSCollector::push_on_overflow_list(oop p) { | |
| 9224 NOT_PRODUCT(_num_par_pushes++;) | |
| 9225 assert(p->is_oop(), "Not an oop"); | |
| 9226 preserve_mark_if_necessary(p); | |
| 9227 p->set_mark((markOop)_overflow_list); | |
| 9228 _overflow_list = p; | |
| 9229 } | |
| 9230 | |
| 9231 // Multi-threaded; use CAS to prepend to overflow list | |
| 9232 void CMSCollector::par_push_on_overflow_list(oop p) { | |
| 9233 NOT_PRODUCT(Atomic::inc_ptr(&_num_par_pushes);) | |
| 9234 assert(p->is_oop(), "Not an oop"); | |
| 9235 par_preserve_mark_if_necessary(p); | |
| 9236 oop observed_overflow_list = _overflow_list; | |
| 9237 oop cur_overflow_list; | |
| 9238 do { | |
| 9239 cur_overflow_list = observed_overflow_list; | |
| 534 | 9240 if (cur_overflow_list != BUSY) { |
| 9241 p->set_mark(markOop(cur_overflow_list)); | |
| 9242 } else { | |
| 9243 p->set_mark(NULL); | |
| 9244 } | |
| 0 | 9245 observed_overflow_list = |
| 9246 (oop) Atomic::cmpxchg_ptr(p, &_overflow_list, cur_overflow_list); | |
| 9247 } while (cur_overflow_list != observed_overflow_list); | |
| 9248 } | |
| 534 | 9249 #undef BUSY |
| 0 | 9250 |
| 9251 // Single threaded | |
| 9252 // General Note on GrowableArray: pushes may silently fail | |
| 9253 // because we are (temporarily) out of C-heap for expanding | |
| 9254 // the stack. The problem is quite ubiquitous and affects | |
| 9255 // a lot of code in the JVM. The prudent thing for GrowableArray | |
| 9256 // to do (for now) is to exit with an error. However, that may | |
| 9257 // be too draconian in some cases because the caller may be | |
| 534 | 9258 // able to recover without much harm. For such cases, we |
| 0 | 9259 // should probably introduce a "soft_push" method which returns |
| 9260 // an indication of success or failure with the assumption that | |
| 9261 // the caller may be able to recover from a failure; code in | |
| 9262 // the VM can then be changed, incrementally, to deal with such | |
| 9263 // failures where possible, thus, incrementally hardening the VM | |
| 9264 // in such low resource situations. | |
| 9265 void CMSCollector::preserve_mark_work(oop p, markOop m) { | |
|
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9266 _preserved_oop_stack.push(p); |
|
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|
9267 _preserved_mark_stack.push(m); |
| 0 | 9268 assert(m == p->mark(), "Mark word changed"); |
|
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|
9269 assert(_preserved_oop_stack.size() == _preserved_mark_stack.size(), |
| 0 | 9270 "bijection"); |
| 9271 } | |
| 9272 | |
| 9273 // Single threaded | |
| 9274 void CMSCollector::preserve_mark_if_necessary(oop p) { | |
| 9275 markOop m = p->mark(); | |
| 9276 if (m->must_be_preserved(p)) { | |
| 9277 preserve_mark_work(p, m); | |
| 9278 } | |
| 9279 } | |
| 9280 | |
| 9281 void CMSCollector::par_preserve_mark_if_necessary(oop p) { | |
| 9282 markOop m = p->mark(); | |
| 9283 if (m->must_be_preserved(p)) { | |
| 9284 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); | |
| 9285 // Even though we read the mark word without holding | |
| 9286 // the lock, we are assured that it will not change | |
| 9287 // because we "own" this oop, so no other thread can | |
| 9288 // be trying to push it on the overflow list; see | |
| 9289 // the assertion in preserve_mark_work() that checks | |
| 9290 // that m == p->mark(). | |
| 9291 preserve_mark_work(p, m); | |
| 9292 } | |
| 9293 } | |
| 9294 | |
| 9295 // We should be able to do this multi-threaded, | |
| 9296 // a chunk of stack being a task (this is | |
| 9297 // correct because each oop only ever appears | |
| 9298 // once in the overflow list. However, it's | |
| 9299 // not very easy to completely overlap this with | |
| 9300 // other operations, so will generally not be done | |
| 9301 // until all work's been completed. Because we | |
| 9302 // expect the preserved oop stack (set) to be small, | |
| 9303 // it's probably fine to do this single-threaded. | |
| 9304 // We can explore cleverer concurrent/overlapped/parallel | |
| 9305 // processing of preserved marks if we feel the | |
| 9306 // need for this in the future. Stack overflow should | |
| 9307 // be so rare in practice and, when it happens, its | |
| 9308 // effect on performance so great that this will | |
| 9309 // likely just be in the noise anyway. | |
| 9310 void CMSCollector::restore_preserved_marks_if_any() { | |
| 9311 assert(SafepointSynchronize::is_at_safepoint(), | |
| 9312 "world should be stopped"); | |
| 9313 assert(Thread::current()->is_ConcurrentGC_thread() || | |
| 9314 Thread::current()->is_VM_thread(), | |
| 9315 "should be single-threaded"); | |
|
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|
9316 assert(_preserved_oop_stack.size() == _preserved_mark_stack.size(), |
|
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|
9317 "bijection"); |
|
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|
9318 |
|
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|
9319 while (!_preserved_oop_stack.is_empty()) { |
|
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|
9320 oop p = _preserved_oop_stack.pop(); |
| 0 | 9321 assert(p->is_oop(), "Should be an oop"); |
| 9322 assert(_span.contains(p), "oop should be in _span"); | |
| 9323 assert(p->mark() == markOopDesc::prototype(), | |
| 9324 "Set when taken from overflow list"); | |
|
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|
9325 markOop m = _preserved_mark_stack.pop(); |
| 0 | 9326 p->set_mark(m); |
| 9327 } | |
|
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|
9328 assert(_preserved_mark_stack.is_empty() && _preserved_oop_stack.is_empty(), |
| 0 | 9329 "stacks were cleared above"); |
| 9330 } | |
| 9331 | |
| 9332 #ifndef PRODUCT | |
| 9333 bool CMSCollector::no_preserved_marks() const { | |
|
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|
9334 return _preserved_mark_stack.is_empty() && _preserved_oop_stack.is_empty(); |
| 0 | 9335 } |
| 9336 #endif | |
| 9337 | |
| 9338 CMSAdaptiveSizePolicy* ASConcurrentMarkSweepGeneration::cms_size_policy() const | |
| 9339 { | |
| 9340 GenCollectedHeap* gch = (GenCollectedHeap*) GenCollectedHeap::heap(); | |
| 9341 CMSAdaptiveSizePolicy* size_policy = | |
| 9342 (CMSAdaptiveSizePolicy*) gch->gen_policy()->size_policy(); | |
| 9343 assert(size_policy->is_gc_cms_adaptive_size_policy(), | |
| 9344 "Wrong type for size policy"); | |
| 9345 return size_policy; | |
| 9346 } | |
| 9347 | |
| 9348 void ASConcurrentMarkSweepGeneration::resize(size_t cur_promo_size, | |
| 9349 size_t desired_promo_size) { | |
| 9350 if (cur_promo_size < desired_promo_size) { | |
| 9351 size_t expand_bytes = desired_promo_size - cur_promo_size; | |
| 9352 if (PrintAdaptiveSizePolicy && Verbose) { | |
| 9353 gclog_or_tty->print_cr(" ASConcurrentMarkSweepGeneration::resize " | |
| 9354 "Expanding tenured generation by " SIZE_FORMAT " (bytes)", | |
| 9355 expand_bytes); | |
| 9356 } | |
| 9357 expand(expand_bytes, | |
| 9358 MinHeapDeltaBytes, | |
| 9359 CMSExpansionCause::_adaptive_size_policy); | |
| 9360 } else if (desired_promo_size < cur_promo_size) { | |
| 9361 size_t shrink_bytes = cur_promo_size - desired_promo_size; | |
| 9362 if (PrintAdaptiveSizePolicy && Verbose) { | |
| 9363 gclog_or_tty->print_cr(" ASConcurrentMarkSweepGeneration::resize " | |
| 9364 "Shrinking tenured generation by " SIZE_FORMAT " (bytes)", | |
| 9365 shrink_bytes); | |
| 9366 } | |
| 9367 shrink(shrink_bytes); | |
| 9368 } | |
| 9369 } | |
| 9370 | |
| 9371 CMSGCAdaptivePolicyCounters* ASConcurrentMarkSweepGeneration::gc_adaptive_policy_counters() { | |
| 9372 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 9373 CMSGCAdaptivePolicyCounters* counters = | |
| 9374 (CMSGCAdaptivePolicyCounters*) gch->collector_policy()->counters(); | |
| 9375 assert(counters->kind() == GCPolicyCounters::CMSGCAdaptivePolicyCountersKind, | |
| 9376 "Wrong kind of counters"); | |
| 9377 return counters; | |
| 9378 } | |
| 9379 | |
| 9380 | |
| 9381 void ASConcurrentMarkSweepGeneration::update_counters() { | |
| 9382 if (UsePerfData) { | |
| 9383 _space_counters->update_all(); | |
| 9384 _gen_counters->update_all(); | |
| 9385 CMSGCAdaptivePolicyCounters* counters = gc_adaptive_policy_counters(); | |
| 9386 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 9387 CMSGCStats* gc_stats_l = (CMSGCStats*) gc_stats(); | |
| 9388 assert(gc_stats_l->kind() == GCStats::CMSGCStatsKind, | |
| 9389 "Wrong gc statistics type"); | |
| 9390 counters->update_counters(gc_stats_l); | |
| 9391 } | |
| 9392 } | |
| 9393 | |
| 9394 void ASConcurrentMarkSweepGeneration::update_counters(size_t used) { | |
| 9395 if (UsePerfData) { | |
| 9396 _space_counters->update_used(used); | |
| 9397 _space_counters->update_capacity(); | |
| 9398 _gen_counters->update_all(); | |
| 9399 | |
| 9400 CMSGCAdaptivePolicyCounters* counters = gc_adaptive_policy_counters(); | |
| 9401 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 9402 CMSGCStats* gc_stats_l = (CMSGCStats*) gc_stats(); | |
| 9403 assert(gc_stats_l->kind() == GCStats::CMSGCStatsKind, | |
| 9404 "Wrong gc statistics type"); | |
| 9405 counters->update_counters(gc_stats_l); | |
| 9406 } | |
| 9407 } | |
| 9408 | |
| 9409 void ASConcurrentMarkSweepGeneration::shrink_by(size_t desired_bytes) { | |
| 9410 assert_locked_or_safepoint(Heap_lock); | |
| 9411 assert_lock_strong(freelistLock()); | |
| 9412 HeapWord* old_end = _cmsSpace->end(); | |
| 9413 HeapWord* unallocated_start = _cmsSpace->unallocated_block(); | |
| 9414 assert(old_end >= unallocated_start, "Miscalculation of unallocated_start"); | |
| 9415 FreeChunk* chunk_at_end = find_chunk_at_end(); | |
| 9416 if (chunk_at_end == NULL) { | |
| 9417 // No room to shrink | |
| 9418 if (PrintGCDetails && Verbose) { | |
| 9419 gclog_or_tty->print_cr("No room to shrink: old_end " | |
| 9420 PTR_FORMAT " unallocated_start " PTR_FORMAT | |
| 9421 " chunk_at_end " PTR_FORMAT, | |
| 9422 old_end, unallocated_start, chunk_at_end); | |
| 9423 } | |
| 9424 return; | |
| 9425 } else { | |
| 9426 | |
| 9427 // Find the chunk at the end of the space and determine | |
| 9428 // how much it can be shrunk. | |
| 9429 size_t shrinkable_size_in_bytes = chunk_at_end->size(); | |
| 9430 size_t aligned_shrinkable_size_in_bytes = | |
| 9431 align_size_down(shrinkable_size_in_bytes, os::vm_page_size()); | |
| 6885 | 9432 assert(unallocated_start <= (HeapWord*) chunk_at_end->end(), |
| 0 | 9433 "Inconsistent chunk at end of space"); |
| 9434 size_t bytes = MIN2(desired_bytes, aligned_shrinkable_size_in_bytes); | |
| 9435 size_t word_size_before = heap_word_size(_virtual_space.committed_size()); | |
| 9436 | |
| 9437 // Shrink the underlying space | |
| 9438 _virtual_space.shrink_by(bytes); | |
| 9439 if (PrintGCDetails && Verbose) { | |
| 9440 gclog_or_tty->print_cr("ConcurrentMarkSweepGeneration::shrink_by:" | |
| 9441 " desired_bytes " SIZE_FORMAT | |
| 9442 " shrinkable_size_in_bytes " SIZE_FORMAT | |
| 9443 " aligned_shrinkable_size_in_bytes " SIZE_FORMAT | |
| 9444 " bytes " SIZE_FORMAT, | |
| 9445 desired_bytes, shrinkable_size_in_bytes, | |
| 9446 aligned_shrinkable_size_in_bytes, bytes); | |
| 9447 gclog_or_tty->print_cr(" old_end " SIZE_FORMAT | |
| 9448 " unallocated_start " SIZE_FORMAT, | |
| 9449 old_end, unallocated_start); | |
| 9450 } | |
| 9451 | |
| 9452 // If the space did shrink (shrinking is not guaranteed), | |
| 9453 // shrink the chunk at the end by the appropriate amount. | |
| 9454 if (((HeapWord*)_virtual_space.high()) < old_end) { | |
| 9455 size_t new_word_size = | |
| 9456 heap_word_size(_virtual_space.committed_size()); | |
| 9457 | |
| 9458 // Have to remove the chunk from the dictionary because it is changing | |
| 9459 // size and might be someplace elsewhere in the dictionary. | |
| 9460 | |
| 9461 // Get the chunk at end, shrink it, and put it | |
| 9462 // back. | |
| 9463 _cmsSpace->removeChunkFromDictionary(chunk_at_end); | |
| 9464 size_t word_size_change = word_size_before - new_word_size; | |
| 9465 size_t chunk_at_end_old_size = chunk_at_end->size(); | |
| 9466 assert(chunk_at_end_old_size >= word_size_change, | |
| 9467 "Shrink is too large"); | |
|
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|
9468 chunk_at_end->set_size(chunk_at_end_old_size - |
| 0 | 9469 word_size_change); |
| 9470 _cmsSpace->freed((HeapWord*) chunk_at_end->end(), | |
| 9471 word_size_change); | |
| 9472 | |
| 9473 _cmsSpace->returnChunkToDictionary(chunk_at_end); | |
| 9474 | |
| 9475 MemRegion mr(_cmsSpace->bottom(), new_word_size); | |
| 9476 _bts->resize(new_word_size); // resize the block offset shared array | |
| 9477 Universe::heap()->barrier_set()->resize_covered_region(mr); | |
| 9478 _cmsSpace->assert_locked(); | |
| 9479 _cmsSpace->set_end((HeapWord*)_virtual_space.high()); | |
| 9480 | |
| 9481 NOT_PRODUCT(_cmsSpace->dictionary()->verify()); | |
| 9482 | |
| 9483 // update the space and generation capacity counters | |
| 9484 if (UsePerfData) { | |
| 9485 _space_counters->update_capacity(); | |
| 9486 _gen_counters->update_all(); | |
| 9487 } | |
| 9488 | |
| 9489 if (Verbose && PrintGCDetails) { | |
| 9490 size_t new_mem_size = _virtual_space.committed_size(); | |
| 9491 size_t old_mem_size = new_mem_size + bytes; | |
|
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|
9492 gclog_or_tty->print_cr("Shrinking %s from " SIZE_FORMAT "K by " SIZE_FORMAT "K to " SIZE_FORMAT "K", |
| 0 | 9493 name(), old_mem_size/K, bytes/K, new_mem_size/K); |
| 9494 } | |
| 9495 } | |
| 9496 | |
| 9497 assert(_cmsSpace->unallocated_block() <= _cmsSpace->end(), | |
| 9498 "Inconsistency at end of space"); | |
| 6885 | 9499 assert(chunk_at_end->end() == (uintptr_t*) _cmsSpace->end(), |
| 0 | 9500 "Shrinking is inconsistent"); |
| 9501 return; | |
| 9502 } | |
| 9503 } | |
| 9504 // Transfer some number of overflown objects to usual marking | |
| 9505 // stack. Return true if some objects were transferred. | |
| 9506 bool MarkRefsIntoAndScanClosure::take_from_overflow_list() { | |
|
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|
9507 size_t num = MIN2((size_t)(_mark_stack->capacity() - _mark_stack->length())/4, |
| 0 | 9508 (size_t)ParGCDesiredObjsFromOverflowList); |
| 9509 | |
| 9510 bool res = _collector->take_from_overflow_list(num, _mark_stack); | |
| 9511 assert(_collector->overflow_list_is_empty() || res, | |
| 9512 "If list is not empty, we should have taken something"); | |
| 9513 assert(!res || !_mark_stack->isEmpty(), | |
| 9514 "If we took something, it should now be on our stack"); | |
| 9515 return res; | |
| 9516 } | |
| 9517 | |
| 9518 size_t MarkDeadObjectsClosure::do_blk(HeapWord* addr) { | |
| 9519 size_t res = _sp->block_size_no_stall(addr, _collector); | |
| 9520 if (_sp->block_is_obj(addr)) { | |
| 9521 if (_live_bit_map->isMarked(addr)) { | |
| 9522 // It can't have been dead in a previous cycle | |
| 9523 guarantee(!_dead_bit_map->isMarked(addr), "No resurrection!"); | |
| 9524 } else { | |
| 9525 _dead_bit_map->mark(addr); // mark the dead object | |
| 9526 } | |
| 9527 } | |
|
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|
9528 // Could be 0, if the block size could not be computed without stalling. |
| 0 | 9529 return res; |
| 9530 } | |
|
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|
9531 |
|
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|
9532 TraceCMSMemoryManagerStats::TraceCMSMemoryManagerStats(CMSCollector::CollectorState phase, GCCause::Cause cause): TraceMemoryManagerStats() { |
|
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|
9533 |
|
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6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
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|
9534 switch (phase) { |
|
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|
9535 case CMSCollector::InitialMarking: |
|
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|
9536 initialize(true /* fullGC */ , |
|
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|
9537 cause /* cause of the GC */, |
|
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|
9538 true /* recordGCBeginTime */, |
|
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1579
diff
changeset
|
9539 true /* recordPreGCUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9540 false /* recordPeakUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9541 false /* recordPostGCusage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9542 true /* recordAccumulatedGCTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9543 false /* recordGCEndTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9544 false /* countCollection */ ); |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9545 break; |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9546 |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9547 case CMSCollector::FinalMarking: |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9548 initialize(true /* fullGC */ , |
|
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
parents:
3293
diff
changeset
|
9549 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
|
9550 false /* recordGCBeginTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9551 false /* recordPreGCUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9552 false /* recordPeakUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9553 false /* recordPostGCusage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9554 true /* recordAccumulatedGCTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9555 false /* recordGCEndTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9556 false /* countCollection */ ); |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9557 break; |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9558 |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9559 case CMSCollector::Sweeping: |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9560 initialize(true /* fullGC */ , |
|
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
parents:
3293
diff
changeset
|
9561 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
|
9562 false /* recordGCBeginTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9563 false /* recordPreGCUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9564 true /* recordPeakUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9565 true /* recordPostGCusage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9566 false /* recordAccumulatedGCTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9567 true /* recordGCEndTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9568 true /* countCollection */ ); |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9569 break; |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9570 |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9571 default: |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9572 ShouldNotReachHere(); |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9573 } |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9574 } |