Mercurial > hg > graal-compiler
annotate src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp @ 14309:63a4eb8bcd23
8025856: Fix typos in the GC code
Summary: Fix about 440 typos in comments in the VM code
Reviewed-by: mgerdin, tschatzl, coleenp, kmo, jcoomes
| author | jwilhelm |
|---|---|
| date | Thu, 23 Jan 2014 14:47:23 +0100 |
| parents | 870aedf4ba4f |
| children | e5d78f318aec |
| rev | line source |
|---|---|
| 0 | 1 /* |
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2 * Copyright (c) 2001, 2013, 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 |
| 66 // statics | |
| 67 CMSCollector* ConcurrentMarkSweepGeneration::_collector = NULL; | |
| 10405 | 68 bool CMSCollector::_full_gc_requested = false; |
| 69 GCCause::Cause CMSCollector::_full_gc_cause = GCCause::_no_gc; | |
| 0 | 70 |
| 71 ////////////////////////////////////////////////////////////////// | |
| 72 // In support of CMS/VM thread synchronization | |
| 73 ////////////////////////////////////////////////////////////////// | |
| 74 // We split use of the CGC_lock into 2 "levels". | |
| 75 // The low-level locking is of the usual CGC_lock monitor. We introduce | |
| 76 // a higher level "token" (hereafter "CMS token") built on top of the | |
| 77 // low level monitor (hereafter "CGC lock"). | |
| 78 // The token-passing protocol gives priority to the VM thread. The | |
| 79 // CMS-lock doesn't provide any fairness guarantees, but clients | |
| 80 // should ensure that it is only held for very short, bounded | |
| 81 // durations. | |
| 82 // | |
| 83 // When either of the CMS thread or the VM thread is involved in | |
| 84 // collection operations during which it does not want the other | |
| 85 // thread to interfere, it obtains the CMS token. | |
| 86 // | |
| 87 // If either thread tries to get the token while the other has | |
| 88 // it, that thread waits. However, if the VM thread and CMS thread | |
| 89 // both want the token, then the VM thread gets priority while the | |
| 90 // CMS thread waits. This ensures, for instance, that the "concurrent" | |
| 91 // phases of the CMS thread's work do not block out the VM thread | |
| 92 // for long periods of time as the CMS thread continues to hog | |
| 93 // the token. (See bug 4616232). | |
| 94 // | |
| 95 // The baton-passing functions are, however, controlled by the | |
| 96 // flags _foregroundGCShouldWait and _foregroundGCIsActive, | |
| 97 // and here the low-level CMS lock, not the high level token, | |
| 98 // ensures mutual exclusion. | |
| 99 // | |
| 100 // Two important conditions that we have to satisfy: | |
| 101 // 1. if a thread does a low-level wait on the CMS lock, then it | |
| 102 // relinquishes the CMS token if it were holding that token | |
| 103 // when it acquired the low-level CMS lock. | |
| 104 // 2. any low-level notifications on the low-level lock | |
| 105 // should only be sent when a thread has relinquished the token. | |
| 106 // | |
| 107 // In the absence of either property, we'd have potential deadlock. | |
| 108 // | |
| 109 // We protect each of the CMS (concurrent and sequential) phases | |
| 110 // with the CMS _token_, not the CMS _lock_. | |
| 111 // | |
| 112 // The only code protected by CMS lock is the token acquisition code | |
| 113 // itself, see ConcurrentMarkSweepThread::[de]synchronize(), and the | |
| 114 // baton-passing code. | |
| 115 // | |
| 116 // Unfortunately, i couldn't come up with a good abstraction to factor and | |
| 117 // hide the naked CGC_lock manipulation in the baton-passing code | |
| 118 // further below. That's something we should try to do. Also, the proof | |
| 119 // of correctness of this 2-level locking scheme is far from obvious, | |
| 14309 | 120 // and potentially quite slippery. We have an uneasy suspicion, for instance, |
| 0 | 121 // that there may be a theoretical possibility of delay/starvation in the |
| 122 // low-level lock/wait/notify scheme used for the baton-passing because of | |
| 14309 | 123 // potential interference with the priority scheme embodied in the |
| 0 | 124 // CMS-token-passing protocol. See related comments at a CGC_lock->wait() |
| 125 // invocation further below and marked with "XXX 20011219YSR". | |
| 126 // Indeed, as we note elsewhere, this may become yet more slippery | |
| 127 // in the presence of multiple CMS and/or multiple VM threads. XXX | |
| 128 | |
| 129 class CMSTokenSync: public StackObj { | |
| 130 private: | |
| 131 bool _is_cms_thread; | |
| 132 public: | |
| 133 CMSTokenSync(bool is_cms_thread): | |
| 134 _is_cms_thread(is_cms_thread) { | |
| 135 assert(is_cms_thread == Thread::current()->is_ConcurrentGC_thread(), | |
| 136 "Incorrect argument to constructor"); | |
| 137 ConcurrentMarkSweepThread::synchronize(_is_cms_thread); | |
| 138 } | |
| 139 | |
| 140 ~CMSTokenSync() { | |
| 141 assert(_is_cms_thread ? | |
| 142 ConcurrentMarkSweepThread::cms_thread_has_cms_token() : | |
| 143 ConcurrentMarkSweepThread::vm_thread_has_cms_token(), | |
| 144 "Incorrect state"); | |
| 145 ConcurrentMarkSweepThread::desynchronize(_is_cms_thread); | |
| 146 } | |
| 147 }; | |
| 148 | |
| 149 // Convenience class that does a CMSTokenSync, and then acquires | |
| 150 // upto three locks. | |
| 151 class CMSTokenSyncWithLocks: public CMSTokenSync { | |
| 152 private: | |
| 153 // Note: locks are acquired in textual declaration order | |
| 154 // and released in the opposite order | |
| 155 MutexLockerEx _locker1, _locker2, _locker3; | |
| 156 public: | |
| 157 CMSTokenSyncWithLocks(bool is_cms_thread, Mutex* mutex1, | |
| 158 Mutex* mutex2 = NULL, Mutex* mutex3 = NULL): | |
| 159 CMSTokenSync(is_cms_thread), | |
| 160 _locker1(mutex1, Mutex::_no_safepoint_check_flag), | |
| 161 _locker2(mutex2, Mutex::_no_safepoint_check_flag), | |
| 162 _locker3(mutex3, Mutex::_no_safepoint_check_flag) | |
| 163 { } | |
| 164 }; | |
| 165 | |
| 166 | |
| 167 // Wrapper class to temporarily disable icms during a foreground cms collection. | |
| 168 class ICMSDisabler: public StackObj { | |
| 169 public: | |
| 170 // The ctor disables icms and wakes up the thread so it notices the change; | |
| 171 // the dtor re-enables icms. Note that the CMSCollector methods will check | |
| 172 // CMSIncrementalMode. | |
| 173 ICMSDisabler() { CMSCollector::disable_icms(); CMSCollector::start_icms(); } | |
| 174 ~ICMSDisabler() { CMSCollector::enable_icms(); } | |
| 175 }; | |
| 176 | |
| 177 ////////////////////////////////////////////////////////////////// | |
| 178 // Concurrent Mark-Sweep Generation ///////////////////////////// | |
| 179 ////////////////////////////////////////////////////////////////// | |
| 180 | |
| 181 NOT_PRODUCT(CompactibleFreeListSpace* debug_cms_space;) | |
| 182 | |
| 183 // This struct contains per-thread things necessary to support parallel | |
| 184 // young-gen collection. | |
| 6197 | 185 class CMSParGCThreadState: public CHeapObj<mtGC> { |
| 0 | 186 public: |
| 187 CFLS_LAB lab; | |
| 188 PromotionInfo promo; | |
| 189 | |
| 190 // Constructor. | |
| 191 CMSParGCThreadState(CompactibleFreeListSpace* cfls) : lab(cfls) { | |
| 192 promo.setSpace(cfls); | |
| 193 } | |
| 194 }; | |
| 195 | |
| 196 ConcurrentMarkSweepGeneration::ConcurrentMarkSweepGeneration( | |
| 197 ReservedSpace rs, size_t initial_byte_size, int level, | |
| 198 CardTableRS* ct, bool use_adaptive_freelists, | |
| 6026 | 199 FreeBlockDictionary<FreeChunk>::DictionaryChoice dictionaryChoice) : |
| 0 | 200 CardGeneration(rs, initial_byte_size, level, ct), |
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201 _dilatation_factor(((double)MinChunkSize)/((double)(CollectedHeap::min_fill_size()))), |
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202 _debug_collection_type(Concurrent_collection_type), |
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203 _did_compact(false) |
| 0 | 204 { |
| 205 HeapWord* bottom = (HeapWord*) _virtual_space.low(); | |
| 206 HeapWord* end = (HeapWord*) _virtual_space.high(); | |
| 207 | |
| 208 _direct_allocated_words = 0; | |
| 209 NOT_PRODUCT( | |
| 210 _numObjectsPromoted = 0; | |
| 211 _numWordsPromoted = 0; | |
| 212 _numObjectsAllocated = 0; | |
| 213 _numWordsAllocated = 0; | |
| 214 ) | |
| 215 | |
| 216 _cmsSpace = new CompactibleFreeListSpace(_bts, MemRegion(bottom, end), | |
| 217 use_adaptive_freelists, | |
| 218 dictionaryChoice); | |
| 219 NOT_PRODUCT(debug_cms_space = _cmsSpace;) | |
| 220 if (_cmsSpace == NULL) { | |
| 221 vm_exit_during_initialization( | |
| 222 "CompactibleFreeListSpace allocation failure"); | |
| 223 } | |
| 224 _cmsSpace->_gen = this; | |
| 225 | |
| 226 _gc_stats = new CMSGCStats(); | |
| 227 | |
| 228 // Verify the assumption that FreeChunk::_prev and OopDesc::_klass | |
| 229 // offsets match. The ability to tell free chunks from objects | |
| 230 // depends on this property. | |
| 231 debug_only( | |
| 232 FreeChunk* junk = NULL; | |
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233 assert(UseCompressedClassPointers || |
| 187 | 234 junk->prev_addr() == (void*)(oop(junk)->klass_addr()), |
| 0 | 235 "Offset of FreeChunk::_prev within FreeChunk must match" |
| 236 " that of OopDesc::_klass within OopDesc"); | |
| 237 ) | |
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238 if (CollectedHeap::use_parallel_gc_threads()) { |
| 0 | 239 typedef CMSParGCThreadState* CMSParGCThreadStatePtr; |
| 240 _par_gc_thread_states = | |
| 6197 | 241 NEW_C_HEAP_ARRAY(CMSParGCThreadStatePtr, ParallelGCThreads, mtGC); |
| 0 | 242 if (_par_gc_thread_states == NULL) { |
| 243 vm_exit_during_initialization("Could not allocate par gc structs"); | |
| 244 } | |
| 245 for (uint i = 0; i < ParallelGCThreads; i++) { | |
| 246 _par_gc_thread_states[i] = new CMSParGCThreadState(cmsSpace()); | |
| 247 if (_par_gc_thread_states[i] == NULL) { | |
| 248 vm_exit_during_initialization("Could not allocate par gc structs"); | |
| 249 } | |
| 250 } | |
| 251 } else { | |
| 252 _par_gc_thread_states = NULL; | |
| 253 } | |
| 254 _incremental_collection_failed = false; | |
| 255 // The "dilatation_factor" is the expansion that can occur on | |
| 256 // account of the fact that the minimum object size in the CMS | |
| 257 // generation may be larger than that in, say, a contiguous young | |
| 258 // generation. | |
| 259 // Ideally, in the calculation below, we'd compute the dilatation | |
| 260 // factor as: MinChunkSize/(promoting_gen's min object size) | |
| 261 // Since we do not have such a general query interface for the | |
| 14309 | 262 // promoting generation, we'll instead just use the minimum |
| 0 | 263 // object size (which today is a header's worth of space); |
| 264 // note that all arithmetic is in units of HeapWords. | |
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265 assert(MinChunkSize >= CollectedHeap::min_fill_size(), "just checking"); |
| 0 | 266 assert(_dilatation_factor >= 1.0, "from previous assert"); |
| 267 } | |
| 268 | |
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269 |
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270 // The field "_initiating_occupancy" represents the occupancy percentage |
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271 // at which we trigger a new collection cycle. Unless explicitly specified |
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272 // via CMSInitiatingOccupancyFraction (argument "io" below), it |
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273 // is calculated by: |
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274 // |
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275 // Let "f" be MinHeapFreeRatio in |
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276 // |
| 14309 | 277 // _initiating_occupancy = 100-f + |
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278 // f * (CMSTriggerRatio/100) |
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279 // where CMSTriggerRatio is the argument "tr" below. |
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280 // |
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281 // That is, if we assume the heap is at its desired maximum occupancy at the |
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282 // end of a collection, we let CMSTriggerRatio of the (purported) free |
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283 // space be allocated before initiating a new collection cycle. |
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284 // |
| 8035 | 285 void ConcurrentMarkSweepGeneration::init_initiating_occupancy(intx io, uintx tr) { |
| 286 assert(io <= 100 && tr <= 100, "Check the arguments"); | |
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287 if (io >= 0) { |
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288 _initiating_occupancy = (double)io / 100.0; |
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289 } else { |
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290 _initiating_occupancy = ((100 - MinHeapFreeRatio) + |
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291 (double)(tr * MinHeapFreeRatio) / 100.0) |
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292 / 100.0; |
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293 } |
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294 } |
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295 |
| 0 | 296 void ConcurrentMarkSweepGeneration::ref_processor_init() { |
| 297 assert(collector() != NULL, "no collector"); | |
| 298 collector()->ref_processor_init(); | |
| 299 } | |
| 300 | |
| 301 void CMSCollector::ref_processor_init() { | |
| 302 if (_ref_processor == NULL) { | |
| 303 // Allocate and initialize a reference processor | |
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304 _ref_processor = |
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305 new ReferenceProcessor(_span, // span |
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306 (ParallelGCThreads > 1) && ParallelRefProcEnabled, // mt processing |
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307 (int) ParallelGCThreads, // mt processing degree |
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308 _cmsGen->refs_discovery_is_mt(), // mt discovery |
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309 (int) MAX2(ConcGCThreads, ParallelGCThreads), // mt discovery degree |
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310 _cmsGen->refs_discovery_is_atomic(), // discovery is not atomic |
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311 &_is_alive_closure, // closure for liveness info |
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312 false); // next field updates do not need write barrier |
| 0 | 313 // Initialize the _ref_processor field of CMSGen |
| 314 _cmsGen->set_ref_processor(_ref_processor); | |
| 315 | |
| 316 } | |
| 317 } | |
| 318 | |
| 319 CMSAdaptiveSizePolicy* CMSCollector::size_policy() { | |
| 320 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 321 assert(gch->kind() == CollectedHeap::GenCollectedHeap, | |
| 322 "Wrong type of heap"); | |
| 323 CMSAdaptiveSizePolicy* sp = (CMSAdaptiveSizePolicy*) | |
| 324 gch->gen_policy()->size_policy(); | |
| 325 assert(sp->is_gc_cms_adaptive_size_policy(), | |
| 326 "Wrong type of size policy"); | |
| 327 return sp; | |
| 328 } | |
| 329 | |
| 330 CMSGCAdaptivePolicyCounters* CMSCollector::gc_adaptive_policy_counters() { | |
| 331 CMSGCAdaptivePolicyCounters* results = | |
| 332 (CMSGCAdaptivePolicyCounters*) collector_policy()->counters(); | |
| 333 assert( | |
| 334 results->kind() == GCPolicyCounters::CMSGCAdaptivePolicyCountersKind, | |
| 335 "Wrong gc policy counter kind"); | |
| 336 return results; | |
| 337 } | |
| 338 | |
| 339 | |
| 340 void ConcurrentMarkSweepGeneration::initialize_performance_counters() { | |
| 341 | |
| 342 const char* gen_name = "old"; | |
| 343 | |
| 344 // Generation Counters - generation 1, 1 subspace | |
| 345 _gen_counters = new GenerationCounters(gen_name, 1, 1, &_virtual_space); | |
| 346 | |
| 347 _space_counters = new GSpaceCounters(gen_name, 0, | |
| 348 _virtual_space.reserved_size(), | |
| 349 this, _gen_counters); | |
| 350 } | |
| 351 | |
| 352 CMSStats::CMSStats(ConcurrentMarkSweepGeneration* cms_gen, unsigned int alpha): | |
| 353 _cms_gen(cms_gen) | |
| 354 { | |
| 355 assert(alpha <= 100, "bad value"); | |
| 356 _saved_alpha = alpha; | |
| 357 | |
| 358 // Initialize the alphas to the bootstrap value of 100. | |
| 359 _gc0_alpha = _cms_alpha = 100; | |
| 360 | |
| 361 _cms_begin_time.update(); | |
| 362 _cms_end_time.update(); | |
| 363 | |
| 364 _gc0_duration = 0.0; | |
| 365 _gc0_period = 0.0; | |
| 366 _gc0_promoted = 0; | |
| 367 | |
| 368 _cms_duration = 0.0; | |
| 369 _cms_period = 0.0; | |
| 370 _cms_allocated = 0; | |
| 371 | |
| 372 _cms_used_at_gc0_begin = 0; | |
| 373 _cms_used_at_gc0_end = 0; | |
| 374 _allow_duty_cycle_reduction = false; | |
| 375 _valid_bits = 0; | |
| 376 _icms_duty_cycle = CMSIncrementalDutyCycle; | |
| 377 } | |
| 378 | |
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379 double CMSStats::cms_free_adjustment_factor(size_t free) const { |
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380 // TBD: CR 6909490 |
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381 return 1.0; |
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382 } |
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383 |
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384 void CMSStats::adjust_cms_free_adjustment_factor(bool fail, size_t free) { |
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385 } |
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386 |
| 0 | 387 // If promotion failure handling is on use |
| 388 // the padded average size of the promotion for each | |
| 389 // young generation collection. | |
| 390 double CMSStats::time_until_cms_gen_full() const { | |
| 391 size_t cms_free = _cms_gen->cmsSpace()->free(); | |
| 392 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
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393 size_t expected_promotion = MIN2(gch->get_gen(0)->capacity(), |
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394 (size_t) _cms_gen->gc_stats()->avg_promoted()->padded_average()); |
| 0 | 395 if (cms_free > expected_promotion) { |
| 396 // Start a cms collection if there isn't enough space to promote | |
| 397 // for the next minor collection. Use the padded average as | |
| 398 // a safety factor. | |
| 399 cms_free -= expected_promotion; | |
| 400 | |
| 401 // Adjust by the safety factor. | |
| 402 double cms_free_dbl = (double)cms_free; | |
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403 double cms_adjustment = (100.0 - CMSIncrementalSafetyFactor)/100.0; |
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404 // Apply a further correction factor which tries to adjust |
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405 // for recent occurance of concurrent mode failures. |
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406 cms_adjustment = cms_adjustment * cms_free_adjustment_factor(cms_free); |
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407 cms_free_dbl = cms_free_dbl * cms_adjustment; |
| 0 | 408 |
| 409 if (PrintGCDetails && Verbose) { | |
| 410 gclog_or_tty->print_cr("CMSStats::time_until_cms_gen_full: cms_free " | |
| 411 SIZE_FORMAT " expected_promotion " SIZE_FORMAT, | |
| 412 cms_free, expected_promotion); | |
| 413 gclog_or_tty->print_cr(" cms_free_dbl %f cms_consumption_rate %f", | |
| 414 cms_free_dbl, cms_consumption_rate() + 1.0); | |
| 415 } | |
| 416 // Add 1 in case the consumption rate goes to zero. | |
| 417 return cms_free_dbl / (cms_consumption_rate() + 1.0); | |
| 418 } | |
| 419 return 0.0; | |
| 420 } | |
| 421 | |
| 422 // Compare the duration of the cms collection to the | |
| 423 // time remaining before the cms generation is empty. | |
| 424 // Note that the time from the start of the cms collection | |
| 425 // to the start of the cms sweep (less than the total | |
| 426 // duration of the cms collection) can be used. This | |
| 427 // has been tried and some applications experienced | |
| 428 // promotion failures early in execution. This was | |
| 429 // possibly because the averages were not accurate | |
| 430 // enough at the beginning. | |
| 431 double CMSStats::time_until_cms_start() const { | |
| 432 // We add "gc0_period" to the "work" calculation | |
| 433 // below because this query is done (mostly) at the | |
| 434 // end of a scavenge, so we need to conservatively | |
| 435 // account for that much possible delay | |
| 436 // in the query so as to avoid concurrent mode failures | |
| 437 // due to starting the collection just a wee bit too | |
| 438 // late. | |
| 439 double work = cms_duration() + gc0_period(); | |
| 440 double deadline = time_until_cms_gen_full(); | |
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441 // If a concurrent mode failure occurred recently, we want to be |
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442 // more conservative and halve our expected time_until_cms_gen_full() |
| 0 | 443 if (work > deadline) { |
| 444 if (Verbose && PrintGCDetails) { | |
| 445 gclog_or_tty->print( | |
| 446 " CMSCollector: collect because of anticipated promotion " | |
| 447 "before full %3.7f + %3.7f > %3.7f ", cms_duration(), | |
| 448 gc0_period(), time_until_cms_gen_full()); | |
| 449 } | |
| 450 return 0.0; | |
| 451 } | |
| 452 return work - deadline; | |
| 453 } | |
| 454 | |
| 455 // Return a duty cycle based on old_duty_cycle and new_duty_cycle, limiting the | |
| 456 // amount of change to prevent wild oscillation. | |
| 457 unsigned int CMSStats::icms_damped_duty_cycle(unsigned int old_duty_cycle, | |
| 458 unsigned int new_duty_cycle) { | |
| 459 assert(old_duty_cycle <= 100, "bad input value"); | |
| 460 assert(new_duty_cycle <= 100, "bad input value"); | |
| 461 | |
| 462 // Note: use subtraction with caution since it may underflow (values are | |
| 463 // unsigned). Addition is safe since we're in the range 0-100. | |
| 464 unsigned int damped_duty_cycle = new_duty_cycle; | |
| 465 if (new_duty_cycle < old_duty_cycle) { | |
| 466 const unsigned int largest_delta = MAX2(old_duty_cycle / 4, 5U); | |
| 467 if (new_duty_cycle + largest_delta < old_duty_cycle) { | |
| 468 damped_duty_cycle = old_duty_cycle - largest_delta; | |
| 469 } | |
| 470 } else if (new_duty_cycle > old_duty_cycle) { | |
| 471 const unsigned int largest_delta = MAX2(old_duty_cycle / 4, 15U); | |
| 472 if (new_duty_cycle > old_duty_cycle + largest_delta) { | |
| 473 damped_duty_cycle = MIN2(old_duty_cycle + largest_delta, 100U); | |
| 474 } | |
| 475 } | |
| 476 assert(damped_duty_cycle <= 100, "invalid duty cycle computed"); | |
| 477 | |
| 478 if (CMSTraceIncrementalPacing) { | |
| 479 gclog_or_tty->print(" [icms_damped_duty_cycle(%d,%d) = %d] ", | |
| 480 old_duty_cycle, new_duty_cycle, damped_duty_cycle); | |
| 481 } | |
| 482 return damped_duty_cycle; | |
| 483 } | |
| 484 | |
| 485 unsigned int CMSStats::icms_update_duty_cycle_impl() { | |
| 486 assert(CMSIncrementalPacing && valid(), | |
| 487 "should be handled in icms_update_duty_cycle()"); | |
| 488 | |
| 489 double cms_time_so_far = cms_timer().seconds(); | |
| 490 double scaled_duration = cms_duration_per_mb() * _cms_used_at_gc0_end / M; | |
| 491 double scaled_duration_remaining = fabsd(scaled_duration - cms_time_so_far); | |
| 492 | |
| 493 // Avoid division by 0. | |
| 494 double time_until_full = MAX2(time_until_cms_gen_full(), 0.01); | |
| 495 double duty_cycle_dbl = 100.0 * scaled_duration_remaining / time_until_full; | |
| 496 | |
| 497 unsigned int new_duty_cycle = MIN2((unsigned int)duty_cycle_dbl, 100U); | |
| 498 if (new_duty_cycle > _icms_duty_cycle) { | |
| 499 // Avoid very small duty cycles (1 or 2); 0 is allowed. | |
| 500 if (new_duty_cycle > 2) { | |
| 501 _icms_duty_cycle = icms_damped_duty_cycle(_icms_duty_cycle, | |
| 502 new_duty_cycle); | |
| 503 } | |
| 504 } else if (_allow_duty_cycle_reduction) { | |
| 505 // The duty cycle is reduced only once per cms cycle (see record_cms_end()). | |
| 506 new_duty_cycle = icms_damped_duty_cycle(_icms_duty_cycle, new_duty_cycle); | |
| 507 // Respect the minimum duty cycle. | |
| 508 unsigned int min_duty_cycle = (unsigned int)CMSIncrementalDutyCycleMin; | |
| 509 _icms_duty_cycle = MAX2(new_duty_cycle, min_duty_cycle); | |
| 510 } | |
| 511 | |
| 512 if (PrintGCDetails || CMSTraceIncrementalPacing) { | |
| 513 gclog_or_tty->print(" icms_dc=%d ", _icms_duty_cycle); | |
| 514 } | |
| 515 | |
| 516 _allow_duty_cycle_reduction = false; | |
| 517 return _icms_duty_cycle; | |
| 518 } | |
| 519 | |
| 520 #ifndef PRODUCT | |
| 521 void CMSStats::print_on(outputStream *st) const { | |
| 522 st->print(" gc0_alpha=%d,cms_alpha=%d", _gc0_alpha, _cms_alpha); | |
| 523 st->print(",gc0_dur=%g,gc0_per=%g,gc0_promo=" SIZE_FORMAT, | |
| 524 gc0_duration(), gc0_period(), gc0_promoted()); | |
| 525 st->print(",cms_dur=%g,cms_dur_per_mb=%g,cms_per=%g,cms_alloc=" SIZE_FORMAT, | |
| 526 cms_duration(), cms_duration_per_mb(), | |
| 527 cms_period(), cms_allocated()); | |
| 528 st->print(",cms_since_beg=%g,cms_since_end=%g", | |
| 529 cms_time_since_begin(), cms_time_since_end()); | |
| 530 st->print(",cms_used_beg=" SIZE_FORMAT ",cms_used_end=" SIZE_FORMAT, | |
| 531 _cms_used_at_gc0_begin, _cms_used_at_gc0_end); | |
| 532 if (CMSIncrementalMode) { | |
| 533 st->print(",dc=%d", icms_duty_cycle()); | |
| 534 } | |
| 535 | |
| 536 if (valid()) { | |
| 537 st->print(",promo_rate=%g,cms_alloc_rate=%g", | |
| 538 promotion_rate(), cms_allocation_rate()); | |
| 539 st->print(",cms_consumption_rate=%g,time_until_full=%g", | |
| 540 cms_consumption_rate(), time_until_cms_gen_full()); | |
| 541 } | |
| 542 st->print(" "); | |
| 543 } | |
| 544 #endif // #ifndef PRODUCT | |
| 545 | |
| 546 CMSCollector::CollectorState CMSCollector::_collectorState = | |
| 547 CMSCollector::Idling; | |
| 548 bool CMSCollector::_foregroundGCIsActive = false; | |
| 549 bool CMSCollector::_foregroundGCShouldWait = false; | |
| 550 | |
| 551 CMSCollector::CMSCollector(ConcurrentMarkSweepGeneration* cmsGen, | |
| 552 CardTableRS* ct, | |
| 553 ConcurrentMarkSweepPolicy* cp): | |
| 554 _cmsGen(cmsGen), | |
| 555 _ct(ct), | |
| 556 _ref_processor(NULL), // will be set later | |
| 557 _conc_workers(NULL), // may be set later | |
| 558 _abort_preclean(false), | |
| 559 _start_sampling(false), | |
| 560 _between_prologue_and_epilogue(false), | |
| 561 _markBitMap(0, Mutex::leaf + 1, "CMS_markBitMap_lock"), | |
| 562 _modUnionTable((CardTableModRefBS::card_shift - LogHeapWordSize), | |
| 563 -1 /* lock-free */, "No_lock" /* dummy */), | |
| 564 _modUnionClosure(&_modUnionTable), | |
| 565 _modUnionClosurePar(&_modUnionTable), | |
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566 // Adjust my span to cover old (cms) gen |
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567 _span(cmsGen->reserved()), |
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568 // Construct the is_alive_closure with _span & markBitMap |
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569 _is_alive_closure(_span, &_markBitMap), |
| 0 | 570 _restart_addr(NULL), |
| 571 _overflow_list(NULL), | |
| 572 _stats(cmsGen), | |
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573 _eden_chunk_lock(new Mutex(Mutex::leaf + 1, "CMS_eden_chunk_lock", true)), |
| 0 | 574 _eden_chunk_array(NULL), // may be set in ctor body |
| 575 _eden_chunk_capacity(0), // -- ditto -- | |
| 576 _eden_chunk_index(0), // -- ditto -- | |
| 577 _survivor_plab_array(NULL), // -- ditto -- | |
| 578 _survivor_chunk_array(NULL), // -- ditto -- | |
| 579 _survivor_chunk_capacity(0), // -- ditto -- | |
| 580 _survivor_chunk_index(0), // -- ditto -- | |
| 581 _ser_pmc_preclean_ovflw(0), | |
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582 _ser_kac_preclean_ovflw(0), |
| 0 | 583 _ser_pmc_remark_ovflw(0), |
| 584 _par_pmc_remark_ovflw(0), | |
| 585 _ser_kac_ovflw(0), | |
| 586 _par_kac_ovflw(0), | |
| 587 #ifndef PRODUCT | |
| 588 _num_par_pushes(0), | |
| 589 #endif | |
| 590 _collection_count_start(0), | |
| 591 _verifying(false), | |
| 592 _icms_start_limit(NULL), | |
| 593 _icms_stop_limit(NULL), | |
| 594 _verification_mark_bm(0, Mutex::leaf + 1, "CMS_verification_mark_bm_lock"), | |
| 595 _completed_initialization(false), | |
| 596 _collector_policy(cp), | |
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597 _should_unload_classes(CMSClassUnloadingEnabled), |
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598 _concurrent_cycles_since_last_unload(0), |
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599 _roots_scanning_options(SharedHeap::SO_None), |
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600 _inter_sweep_estimate(CMS_SweepWeight, CMS_SweepPadding), |
| 10405 | 601 _intra_sweep_estimate(CMS_SweepWeight, CMS_SweepPadding), |
| 602 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) CMSTracer()), | |
| 603 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), | |
| 604 _cms_start_registered(false) | |
| 0 | 605 { |
| 606 if (ExplicitGCInvokesConcurrentAndUnloadsClasses) { | |
| 607 ExplicitGCInvokesConcurrent = true; | |
| 608 } | |
| 609 // Now expand the span and allocate the collection support structures | |
| 610 // (MUT, marking bit map etc.) to cover both generations subject to | |
| 611 // collection. | |
| 612 | |
| 613 // For use by dirty card to oop closures. | |
| 614 _cmsGen->cmsSpace()->set_collector(this); | |
| 615 | |
| 616 // Allocate MUT and marking bit map | |
| 617 { | |
| 618 MutexLockerEx x(_markBitMap.lock(), Mutex::_no_safepoint_check_flag); | |
| 619 if (!_markBitMap.allocate(_span)) { | |
| 620 warning("Failed to allocate CMS Bit Map"); | |
| 621 return; | |
| 622 } | |
| 623 assert(_markBitMap.covers(_span), "_markBitMap inconsistency?"); | |
| 624 } | |
| 625 { | |
| 626 _modUnionTable.allocate(_span); | |
| 627 assert(_modUnionTable.covers(_span), "_modUnionTable inconsistency?"); | |
| 628 } | |
| 629 | |
| 1284 | 630 if (!_markStack.allocate(MarkStackSize)) { |
| 0 | 631 warning("Failed to allocate CMS Marking Stack"); |
| 632 return; | |
| 633 } | |
| 634 | |
| 635 // Support for multi-threaded concurrent phases | |
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636 if (CMSConcurrentMTEnabled) { |
| 1284 | 637 if (FLAG_IS_DEFAULT(ConcGCThreads)) { |
| 0 | 638 // just for now |
| 1284 | 639 FLAG_SET_DEFAULT(ConcGCThreads, (ParallelGCThreads + 3)/4); |
| 640 } | |
| 641 if (ConcGCThreads > 1) { | |
| 0 | 642 _conc_workers = new YieldingFlexibleWorkGang("Parallel CMS Threads", |
| 1284 | 643 ConcGCThreads, true); |
| 0 | 644 if (_conc_workers == NULL) { |
| 645 warning("GC/CMS: _conc_workers allocation failure: " | |
| 646 "forcing -CMSConcurrentMTEnabled"); | |
| 647 CMSConcurrentMTEnabled = false; | |
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648 } else { |
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649 _conc_workers->initialize_workers(); |
| 0 | 650 } |
| 651 } else { | |
| 652 CMSConcurrentMTEnabled = false; | |
| 653 } | |
| 654 } | |
| 655 if (!CMSConcurrentMTEnabled) { | |
| 1284 | 656 ConcGCThreads = 0; |
| 0 | 657 } else { |
| 658 // Turn off CMSCleanOnEnter optimization temporarily for | |
| 659 // the MT case where it's not fixed yet; see 6178663. | |
| 660 CMSCleanOnEnter = false; | |
| 661 } | |
| 1284 | 662 assert((_conc_workers != NULL) == (ConcGCThreads > 1), |
| 0 | 663 "Inconsistency"); |
| 664 | |
| 665 // Parallel task queues; these are shared for the | |
| 666 // concurrent and stop-world phases of CMS, but | |
| 667 // are not shared with parallel scavenge (ParNew). | |
| 668 { | |
| 669 uint i; | |
| 1284 | 670 uint num_queues = (uint) MAX2(ParallelGCThreads, ConcGCThreads); |
| 0 | 671 |
| 672 if ((CMSParallelRemarkEnabled || CMSConcurrentMTEnabled | |
| 673 || ParallelRefProcEnabled) | |
| 674 && num_queues > 0) { | |
| 675 _task_queues = new OopTaskQueueSet(num_queues); | |
| 676 if (_task_queues == NULL) { | |
| 677 warning("task_queues allocation failure."); | |
| 678 return; | |
| 679 } | |
| 6197 | 680 _hash_seed = NEW_C_HEAP_ARRAY(int, num_queues, mtGC); |
| 0 | 681 if (_hash_seed == NULL) { |
| 682 warning("_hash_seed array allocation failure"); | |
| 683 return; | |
| 684 } | |
| 685 | |
| 1665 | 686 typedef Padded<OopTaskQueue> PaddedOopTaskQueue; |
| 0 | 687 for (i = 0; i < num_queues; i++) { |
| 1665 | 688 PaddedOopTaskQueue *q = new PaddedOopTaskQueue(); |
| 689 if (q == NULL) { | |
| 0 | 690 warning("work_queue allocation failure."); |
| 691 return; | |
| 692 } | |
| 1665 | 693 _task_queues->register_queue(i, q); |
| 0 | 694 } |
| 695 for (i = 0; i < num_queues; i++) { | |
| 696 _task_queues->queue(i)->initialize(); | |
| 697 _hash_seed[i] = 17; // copied from ParNew | |
| 698 } | |
| 699 } | |
| 700 } | |
| 701 | |
|
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702 _cmsGen ->init_initiating_occupancy(CMSInitiatingOccupancyFraction, CMSTriggerRatio); |
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703 |
| 0 | 704 // Clip CMSBootstrapOccupancy between 0 and 100. |
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705 _bootstrap_occupancy = ((double)CMSBootstrapOccupancy)/(double)100; |
| 0 | 706 |
| 707 _full_gcs_since_conc_gc = 0; | |
| 708 | |
| 709 // Now tell CMS generations the identity of their collector | |
| 710 ConcurrentMarkSweepGeneration::set_collector(this); | |
| 711 | |
| 712 // Create & start a CMS thread for this CMS collector | |
| 713 _cmsThread = ConcurrentMarkSweepThread::start(this); | |
| 714 assert(cmsThread() != NULL, "CMS Thread should have been created"); | |
| 715 assert(cmsThread()->collector() == this, | |
| 716 "CMS Thread should refer to this gen"); | |
| 717 assert(CGC_lock != NULL, "Where's the CGC_lock?"); | |
| 718 | |
| 719 // Support for parallelizing young gen rescan | |
| 720 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 721 _young_gen = gch->prev_gen(_cmsGen); | |
| 722 if (gch->supports_inline_contig_alloc()) { | |
| 723 _top_addr = gch->top_addr(); | |
| 724 _end_addr = gch->end_addr(); | |
| 725 assert(_young_gen != NULL, "no _young_gen"); | |
| 726 _eden_chunk_index = 0; | |
| 727 _eden_chunk_capacity = (_young_gen->max_capacity()+CMSSamplingGrain)/CMSSamplingGrain; | |
| 6197 | 728 _eden_chunk_array = NEW_C_HEAP_ARRAY(HeapWord*, _eden_chunk_capacity, mtGC); |
| 0 | 729 if (_eden_chunk_array == NULL) { |
| 730 _eden_chunk_capacity = 0; | |
| 731 warning("GC/CMS: _eden_chunk_array allocation failure"); | |
| 732 } | |
| 733 } | |
| 734 assert(_eden_chunk_array != NULL || _eden_chunk_capacity == 0, "Error"); | |
| 735 | |
| 736 // Support for parallelizing survivor space rescan | |
| 11975 | 737 if ((CMSParallelRemarkEnabled && CMSParallelSurvivorRemarkEnabled) || CMSParallelInitialMarkEnabled) { |
|
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738 const size_t max_plab_samples = |
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739 ((DefNewGeneration*)_young_gen)->max_survivor_size()/MinTLABSize; |
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740 |
| 6197 | 741 _survivor_plab_array = NEW_C_HEAP_ARRAY(ChunkArray, ParallelGCThreads, mtGC); |
| 742 _survivor_chunk_array = NEW_C_HEAP_ARRAY(HeapWord*, 2*max_plab_samples, mtGC); | |
| 743 _cursor = NEW_C_HEAP_ARRAY(size_t, ParallelGCThreads, mtGC); | |
| 0 | 744 if (_survivor_plab_array == NULL || _survivor_chunk_array == NULL |
| 745 || _cursor == NULL) { | |
| 746 warning("Failed to allocate survivor plab/chunk array"); | |
| 747 if (_survivor_plab_array != NULL) { | |
| 6197 | 748 FREE_C_HEAP_ARRAY(ChunkArray, _survivor_plab_array, mtGC); |
| 0 | 749 _survivor_plab_array = NULL; |
| 750 } | |
| 751 if (_survivor_chunk_array != NULL) { | |
| 6197 | 752 FREE_C_HEAP_ARRAY(HeapWord*, _survivor_chunk_array, mtGC); |
| 0 | 753 _survivor_chunk_array = NULL; |
| 754 } | |
| 755 if (_cursor != NULL) { | |
| 6197 | 756 FREE_C_HEAP_ARRAY(size_t, _cursor, mtGC); |
| 0 | 757 _cursor = NULL; |
| 758 } | |
| 759 } else { | |
| 760 _survivor_chunk_capacity = 2*max_plab_samples; | |
| 761 for (uint i = 0; i < ParallelGCThreads; i++) { | |
| 6197 | 762 HeapWord** vec = NEW_C_HEAP_ARRAY(HeapWord*, max_plab_samples, mtGC); |
| 0 | 763 if (vec == NULL) { |
| 764 warning("Failed to allocate survivor plab array"); | |
| 765 for (int j = i; j > 0; j--) { | |
| 6197 | 766 FREE_C_HEAP_ARRAY(HeapWord*, _survivor_plab_array[j-1].array(), mtGC); |
| 0 | 767 } |
| 6197 | 768 FREE_C_HEAP_ARRAY(ChunkArray, _survivor_plab_array, mtGC); |
| 769 FREE_C_HEAP_ARRAY(HeapWord*, _survivor_chunk_array, mtGC); | |
| 0 | 770 _survivor_plab_array = NULL; |
| 771 _survivor_chunk_array = NULL; | |
| 772 _survivor_chunk_capacity = 0; | |
| 773 break; | |
| 774 } else { | |
| 775 ChunkArray* cur = | |
| 776 ::new (&_survivor_plab_array[i]) ChunkArray(vec, | |
| 777 max_plab_samples); | |
| 778 assert(cur->end() == 0, "Should be 0"); | |
| 779 assert(cur->array() == vec, "Should be vec"); | |
| 780 assert(cur->capacity() == max_plab_samples, "Error"); | |
| 781 } | |
| 782 } | |
| 783 } | |
| 784 } | |
| 785 assert( ( _survivor_plab_array != NULL | |
| 786 && _survivor_chunk_array != NULL) | |
| 787 || ( _survivor_chunk_capacity == 0 | |
| 788 && _survivor_chunk_index == 0), | |
| 789 "Error"); | |
| 790 | |
| 791 NOT_PRODUCT(_overflow_counter = CMSMarkStackOverflowInterval;) | |
| 792 _gc_counters = new CollectorCounters("CMS", 1); | |
| 793 _completed_initialization = true; | |
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794 _inter_sweep_timer.start(); // start of time |
| 0 | 795 } |
| 796 | |
| 797 const char* ConcurrentMarkSweepGeneration::name() const { | |
| 798 return "concurrent mark-sweep generation"; | |
| 799 } | |
| 800 void ConcurrentMarkSweepGeneration::update_counters() { | |
| 801 if (UsePerfData) { | |
| 802 _space_counters->update_all(); | |
| 803 _gen_counters->update_all(); | |
| 804 } | |
| 805 } | |
| 806 | |
| 807 // this is an optimized version of update_counters(). it takes the | |
| 808 // used value as a parameter rather than computing it. | |
| 809 // | |
| 810 void ConcurrentMarkSweepGeneration::update_counters(size_t used) { | |
| 811 if (UsePerfData) { | |
| 812 _space_counters->update_used(used); | |
| 813 _space_counters->update_capacity(); | |
| 814 _gen_counters->update_all(); | |
| 815 } | |
| 816 } | |
| 817 | |
| 818 void ConcurrentMarkSweepGeneration::print() const { | |
| 819 Generation::print(); | |
| 820 cmsSpace()->print(); | |
| 821 } | |
| 822 | |
| 823 #ifndef PRODUCT | |
| 824 void ConcurrentMarkSweepGeneration::print_statistics() { | |
| 825 cmsSpace()->printFLCensus(0); | |
| 826 } | |
| 827 #endif | |
| 828 | |
| 829 void ConcurrentMarkSweepGeneration::printOccupancy(const char *s) { | |
| 830 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 831 if (PrintGCDetails) { | |
| 832 if (Verbose) { | |
|
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833 gclog_or_tty->print("[%d %s-%s: "SIZE_FORMAT"("SIZE_FORMAT")]", |
| 0 | 834 level(), short_name(), s, used(), capacity()); |
| 835 } else { | |
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836 gclog_or_tty->print("[%d %s-%s: "SIZE_FORMAT"K("SIZE_FORMAT"K)]", |
| 0 | 837 level(), short_name(), s, used() / K, capacity() / K); |
| 838 } | |
| 839 } | |
| 840 if (Verbose) { | |
| 841 gclog_or_tty->print(" "SIZE_FORMAT"("SIZE_FORMAT")", | |
| 842 gch->used(), gch->capacity()); | |
| 843 } else { | |
| 844 gclog_or_tty->print(" "SIZE_FORMAT"K("SIZE_FORMAT"K)", | |
| 845 gch->used() / K, gch->capacity() / K); | |
| 846 } | |
| 847 } | |
| 848 | |
| 849 size_t | |
| 850 ConcurrentMarkSweepGeneration::contiguous_available() const { | |
| 851 // dld proposes an improvement in precision here. If the committed | |
| 852 // part of the space ends in a free block we should add that to | |
| 853 // uncommitted size in the calculation below. Will make this | |
| 854 // change later, staying with the approximation below for the | |
| 855 // time being. -- ysr. | |
| 856 return MAX2(_virtual_space.uncommitted_size(), unsafe_max_alloc_nogc()); | |
| 857 } | |
| 858 | |
| 859 size_t | |
| 860 ConcurrentMarkSweepGeneration::unsafe_max_alloc_nogc() const { | |
| 861 return _cmsSpace->max_alloc_in_words() * HeapWordSize; | |
| 862 } | |
| 863 | |
| 864 size_t ConcurrentMarkSweepGeneration::max_available() const { | |
| 865 return free() + _virtual_space.uncommitted_size(); | |
| 866 } | |
| 867 | |
|
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868 bool ConcurrentMarkSweepGeneration::promotion_attempt_is_safe(size_t max_promotion_in_bytes) const { |
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869 size_t available = max_available(); |
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870 size_t av_promo = (size_t)gc_stats()->avg_promoted()->padded_average(); |
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871 bool res = (available >= av_promo) || (available >= max_promotion_in_bytes); |
|
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872 if (Verbose && PrintGCDetails) { |
|
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873 gclog_or_tty->print_cr( |
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874 "CMS: promo attempt is%s safe: available("SIZE_FORMAT") %s av_promo("SIZE_FORMAT")," |
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875 "max_promo("SIZE_FORMAT")", |
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876 res? "":" not", available, res? ">=":"<", |
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877 av_promo, max_promotion_in_bytes); |
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878 } |
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879 return res; |
| 0 | 880 } |
| 881 | |
|
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882 // At a promotion failure dump information on block layout in heap |
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883 // (cms old generation). |
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884 void ConcurrentMarkSweepGeneration::promotion_failure_occurred() { |
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885 if (CMSDumpAtPromotionFailure) { |
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886 cmsSpace()->dump_at_safepoint_with_locks(collector(), gclog_or_tty); |
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887 } |
|
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888 } |
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|
889 |
| 0 | 890 CompactibleSpace* |
| 891 ConcurrentMarkSweepGeneration::first_compaction_space() const { | |
| 892 return _cmsSpace; | |
| 893 } | |
| 894 | |
| 895 void ConcurrentMarkSweepGeneration::reset_after_compaction() { | |
| 896 // Clear the promotion information. These pointers can be adjusted | |
| 897 // along with all the other pointers into the heap but | |
| 898 // compaction is expected to be a rare event with | |
| 899 // a heap using cms so don't do it without seeing the need. | |
|
1833
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900 if (CollectedHeap::use_parallel_gc_threads()) { |
| 0 | 901 for (uint i = 0; i < ParallelGCThreads; i++) { |
| 902 _par_gc_thread_states[i]->promo.reset(); | |
| 903 } | |
| 904 } | |
| 905 } | |
| 906 | |
| 907 void ConcurrentMarkSweepGeneration::space_iterate(SpaceClosure* blk, bool usedOnly) { | |
| 908 blk->do_space(_cmsSpace); | |
| 909 } | |
| 910 | |
| 911 void ConcurrentMarkSweepGeneration::compute_new_size() { | |
| 912 assert_locked_or_safepoint(Heap_lock); | |
| 913 | |
| 914 // If incremental collection failed, we just want to expand | |
| 915 // to the limit. | |
| 916 if (incremental_collection_failed()) { | |
| 917 clear_incremental_collection_failed(); | |
| 918 grow_to_reserved(); | |
| 919 return; | |
| 920 } | |
| 921 | |
|
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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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922 // The heap has been compacted but not reset yet. |
|
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923 // Any metric such as free() or used() will be incorrect. |
|
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924 |
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925 CardGeneration::compute_new_size(); |
|
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926 |
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927 // Reset again after a possible resizing |
|
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928 if (did_compact()) { |
|
06ab37f08701
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929 cmsSpace()->reset_after_compaction(); |
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930 } |
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931 } |
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932 |
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933 void ConcurrentMarkSweepGeneration::compute_new_size_free_list() { |
|
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934 assert_locked_or_safepoint(Heap_lock); |
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935 |
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936 // If incremental collection failed, we just want to expand |
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937 // to the limit. |
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938 if (incremental_collection_failed()) { |
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939 clear_incremental_collection_failed(); |
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940 grow_to_reserved(); |
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941 return; |
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|
942 } |
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943 |
| 0 | 944 double free_percentage = ((double) free()) / capacity(); |
| 945 double desired_free_percentage = (double) MinHeapFreeRatio / 100; | |
| 946 double maximum_free_percentage = (double) MaxHeapFreeRatio / 100; | |
| 947 | |
| 948 // compute expansion delta needed for reaching desired free percentage | |
| 949 if (free_percentage < desired_free_percentage) { | |
| 950 size_t desired_capacity = (size_t)(used() / ((double) 1 - desired_free_percentage)); | |
| 951 assert(desired_capacity >= capacity(), "invalid expansion size"); | |
|
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952 size_t expand_bytes = MAX2(desired_capacity - capacity(), MinHeapDeltaBytes); |
| 0 | 953 if (PrintGCDetails && Verbose) { |
| 954 size_t desired_capacity = (size_t)(used() / ((double) 1 - desired_free_percentage)); | |
| 955 gclog_or_tty->print_cr("\nFrom compute_new_size: "); | |
| 956 gclog_or_tty->print_cr(" Free fraction %f", free_percentage); | |
| 957 gclog_or_tty->print_cr(" Desired free fraction %f", | |
| 958 desired_free_percentage); | |
| 959 gclog_or_tty->print_cr(" Maximum free fraction %f", | |
| 960 maximum_free_percentage); | |
| 961 gclog_or_tty->print_cr(" Capactiy "SIZE_FORMAT, capacity()/1000); | |
| 962 gclog_or_tty->print_cr(" Desired capacity "SIZE_FORMAT, | |
| 963 desired_capacity/1000); | |
| 964 int prev_level = level() - 1; | |
| 965 if (prev_level >= 0) { | |
| 966 size_t prev_size = 0; | |
| 967 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 968 Generation* prev_gen = gch->_gens[prev_level]; | |
| 969 prev_size = prev_gen->capacity(); | |
| 970 gclog_or_tty->print_cr(" Younger gen size "SIZE_FORMAT, | |
| 971 prev_size/1000); | |
| 972 } | |
| 973 gclog_or_tty->print_cr(" unsafe_max_alloc_nogc "SIZE_FORMAT, | |
| 974 unsafe_max_alloc_nogc()/1000); | |
| 975 gclog_or_tty->print_cr(" contiguous available "SIZE_FORMAT, | |
| 976 contiguous_available()/1000); | |
| 977 gclog_or_tty->print_cr(" Expand by "SIZE_FORMAT" (bytes)", | |
| 978 expand_bytes); | |
| 979 } | |
| 980 // safe if expansion fails | |
| 981 expand(expand_bytes, 0, CMSExpansionCause::_satisfy_free_ratio); | |
| 982 if (PrintGCDetails && Verbose) { | |
| 983 gclog_or_tty->print_cr(" Expanded free fraction %f", | |
| 984 ((double) free()) / capacity()); | |
| 985 } | |
|
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986 } else { |
|
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987 size_t desired_capacity = (size_t)(used() / ((double) 1 - desired_free_percentage)); |
|
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988 assert(desired_capacity <= capacity(), "invalid expansion size"); |
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989 size_t shrink_bytes = capacity() - desired_capacity; |
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990 // Don't shrink unless the delta is greater than the minimum shrink we want |
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991 if (shrink_bytes >= MinHeapDeltaBytes) { |
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992 shrink_free_list_by(shrink_bytes); |
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993 } |
| 0 | 994 } |
| 995 } | |
| 996 | |
| 997 Mutex* ConcurrentMarkSweepGeneration::freelistLock() const { | |
| 998 return cmsSpace()->freelistLock(); | |
| 999 } | |
| 1000 | |
| 1001 HeapWord* ConcurrentMarkSweepGeneration::allocate(size_t size, | |
| 1002 bool tlab) { | |
| 1003 CMSSynchronousYieldRequest yr; | |
| 1004 MutexLockerEx x(freelistLock(), | |
| 1005 Mutex::_no_safepoint_check_flag); | |
| 1006 return have_lock_and_allocate(size, tlab); | |
| 1007 } | |
| 1008 | |
| 1009 HeapWord* ConcurrentMarkSweepGeneration::have_lock_and_allocate(size_t size, | |
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1010 bool tlab /* ignored */) { |
| 0 | 1011 assert_lock_strong(freelistLock()); |
| 1012 size_t adjustedSize = CompactibleFreeListSpace::adjustObjectSize(size); | |
| 1013 HeapWord* res = cmsSpace()->allocate(adjustedSize); | |
| 1014 // Allocate the object live (grey) if the background collector has | |
| 1015 // started marking. This is necessary because the marker may | |
| 1016 // have passed this address and consequently this object will | |
| 1017 // not otherwise be greyed and would be incorrectly swept up. | |
| 1018 // Note that if this object contains references, the writing | |
| 1019 // of those references will dirty the card containing this object | |
| 1020 // allowing the object to be blackened (and its references scanned) | |
| 1021 // either during a preclean phase or at the final checkpoint. | |
| 1022 if (res != NULL) { | |
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1023 // We may block here with an uninitialized object with |
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1024 // its mark-bit or P-bits not yet set. Such objects need |
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1025 // to be safely navigable by block_start(). |
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1026 assert(oop(res)->klass_or_null() == NULL, "Object should be uninitialized here."); |
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1027 assert(!((FreeChunk*)res)->is_free(), "Error, block will look free but show wrong size"); |
| 0 | 1028 collector()->direct_allocated(res, adjustedSize); |
| 1029 _direct_allocated_words += adjustedSize; | |
| 1030 // allocation counters | |
| 1031 NOT_PRODUCT( | |
| 1032 _numObjectsAllocated++; | |
| 1033 _numWordsAllocated += (int)adjustedSize; | |
| 1034 ) | |
| 1035 } | |
| 1036 return res; | |
| 1037 } | |
| 1038 | |
| 1039 // In the case of direct allocation by mutators in a generation that | |
| 1040 // is being concurrently collected, the object must be allocated | |
| 1041 // live (grey) if the background collector has started marking. | |
| 1042 // This is necessary because the marker may | |
| 1043 // have passed this address and consequently this object will | |
| 1044 // not otherwise be greyed and would be incorrectly swept up. | |
| 1045 // Note that if this object contains references, the writing | |
| 1046 // of those references will dirty the card containing this object | |
| 1047 // allowing the object to be blackened (and its references scanned) | |
| 1048 // either during a preclean phase or at the final checkpoint. | |
| 1049 void CMSCollector::direct_allocated(HeapWord* start, size_t size) { | |
| 1050 assert(_markBitMap.covers(start, size), "Out of bounds"); | |
| 1051 if (_collectorState >= Marking) { | |
| 1052 MutexLockerEx y(_markBitMap.lock(), | |
| 1053 Mutex::_no_safepoint_check_flag); | |
| 1054 // [see comments preceding SweepClosure::do_blk() below for details] | |
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1055 // |
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1056 // Can the P-bits be deleted now? JJJ |
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1057 // |
| 0 | 1058 // 1. need to mark the object as live so it isn't collected |
| 1059 // 2. need to mark the 2nd bit to indicate the object may be uninitialized | |
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1060 // 3. need to mark the end of the object so marking, precleaning or sweeping |
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1061 // can skip over uninitialized or unparsable objects. An allocated |
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1062 // object is considered uninitialized for our purposes as long as |
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1063 // its klass word is NULL. All old gen objects are parsable |
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1064 // as soon as they are initialized.) |
| 0 | 1065 _markBitMap.mark(start); // object is live |
| 1066 _markBitMap.mark(start + 1); // object is potentially uninitialized? | |
| 1067 _markBitMap.mark(start + size - 1); | |
| 1068 // mark end of object | |
| 1069 } | |
| 1070 // check that oop looks uninitialized | |
| 187 | 1071 assert(oop(start)->klass_or_null() == NULL, "_klass should be NULL"); |
| 0 | 1072 } |
| 1073 | |
| 1074 void CMSCollector::promoted(bool par, HeapWord* start, | |
| 1075 bool is_obj_array, size_t obj_size) { | |
| 1076 assert(_markBitMap.covers(start), "Out of bounds"); | |
| 1077 // See comment in direct_allocated() about when objects should | |
| 1078 // be allocated live. | |
| 1079 if (_collectorState >= Marking) { | |
| 1080 // we already hold the marking bit map lock, taken in | |
| 1081 // the prologue | |
| 1082 if (par) { | |
| 1083 _markBitMap.par_mark(start); | |
| 1084 } else { | |
| 1085 _markBitMap.mark(start); | |
| 1086 } | |
| 1087 // We don't need to mark the object as uninitialized (as | |
| 1088 // in direct_allocated above) because this is being done with the | |
| 1089 // world stopped and the object will be initialized by the | |
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1090 // time the marking, precleaning or sweeping get to look at it. |
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1091 // But see the code for copying objects into the CMS generation, |
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1092 // where we need to ensure that concurrent readers of the |
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1093 // block offset table are able to safely navigate a block that |
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1094 // is in flux from being free to being allocated (and in |
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1095 // transition while being copied into) and subsequently |
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1096 // becoming a bona-fide object when the copy/promotion is complete. |
| 0 | 1097 assert(SafepointSynchronize::is_at_safepoint(), |
| 1098 "expect promotion only at safepoints"); | |
| 1099 | |
| 1100 if (_collectorState < Sweeping) { | |
| 1101 // Mark the appropriate cards in the modUnionTable, so that | |
| 1102 // this object gets scanned before the sweep. If this is | |
| 1103 // not done, CMS generation references in the object might | |
| 1104 // not get marked. | |
| 1105 // For the case of arrays, which are otherwise precisely | |
| 1106 // marked, we need to dirty the entire array, not just its head. | |
| 1107 if (is_obj_array) { | |
| 1108 // The [par_]mark_range() method expects mr.end() below to | |
| 1109 // be aligned to the granularity of a bit's representation | |
| 1110 // in the heap. In the case of the MUT below, that's a | |
| 1111 // card size. | |
| 1112 MemRegion mr(start, | |
| 1113 (HeapWord*)round_to((intptr_t)(start + obj_size), | |
| 1114 CardTableModRefBS::card_size /* bytes */)); | |
| 1115 if (par) { | |
| 1116 _modUnionTable.par_mark_range(mr); | |
| 1117 } else { | |
| 1118 _modUnionTable.mark_range(mr); | |
| 1119 } | |
| 1120 } else { // not an obj array; we can just mark the head | |
| 1121 if (par) { | |
| 1122 _modUnionTable.par_mark(start); | |
| 1123 } else { | |
| 1124 _modUnionTable.mark(start); | |
| 1125 } | |
| 1126 } | |
| 1127 } | |
| 1128 } | |
| 1129 } | |
| 1130 | |
| 1131 static inline size_t percent_of_space(Space* space, HeapWord* addr) | |
| 1132 { | |
| 1133 size_t delta = pointer_delta(addr, space->bottom()); | |
| 1134 return (size_t)(delta * 100.0 / (space->capacity() / HeapWordSize)); | |
| 1135 } | |
| 1136 | |
| 1137 void CMSCollector::icms_update_allocation_limits() | |
| 1138 { | |
| 1139 Generation* gen0 = GenCollectedHeap::heap()->get_gen(0); | |
| 1140 EdenSpace* eden = gen0->as_DefNewGeneration()->eden(); | |
| 1141 | |
| 1142 const unsigned int duty_cycle = stats().icms_update_duty_cycle(); | |
| 1143 if (CMSTraceIncrementalPacing) { | |
| 1144 stats().print(); | |
| 1145 } | |
| 1146 | |
| 1147 assert(duty_cycle <= 100, "invalid duty cycle"); | |
| 1148 if (duty_cycle != 0) { | |
| 1149 // The duty_cycle is a percentage between 0 and 100; convert to words and | |
| 1150 // then compute the offset from the endpoints of the space. | |
| 1151 size_t free_words = eden->free() / HeapWordSize; | |
| 1152 double free_words_dbl = (double)free_words; | |
| 1153 size_t duty_cycle_words = (size_t)(free_words_dbl * duty_cycle / 100.0); | |
| 1154 size_t offset_words = (free_words - duty_cycle_words) / 2; | |
| 1155 | |
| 1156 _icms_start_limit = eden->top() + offset_words; | |
| 1157 _icms_stop_limit = eden->end() - offset_words; | |
| 1158 | |
| 1159 // The limits may be adjusted (shifted to the right) by | |
| 1160 // CMSIncrementalOffset, to allow the application more mutator time after a | |
| 1161 // young gen gc (when all mutators were stopped) and before CMS starts and | |
| 1162 // takes away one or more cpus. | |
| 1163 if (CMSIncrementalOffset != 0) { | |
| 1164 double adjustment_dbl = free_words_dbl * CMSIncrementalOffset / 100.0; | |
| 1165 size_t adjustment = (size_t)adjustment_dbl; | |
| 1166 HeapWord* tmp_stop = _icms_stop_limit + adjustment; | |
| 1167 if (tmp_stop > _icms_stop_limit && tmp_stop < eden->end()) { | |
| 1168 _icms_start_limit += adjustment; | |
| 1169 _icms_stop_limit = tmp_stop; | |
| 1170 } | |
| 1171 } | |
| 1172 } | |
| 1173 if (duty_cycle == 0 || (_icms_start_limit == _icms_stop_limit)) { | |
| 1174 _icms_start_limit = _icms_stop_limit = eden->end(); | |
| 1175 } | |
| 1176 | |
| 1177 // Install the new start limit. | |
| 1178 eden->set_soft_end(_icms_start_limit); | |
| 1179 | |
| 1180 if (CMSTraceIncrementalMode) { | |
| 1181 gclog_or_tty->print(" icms alloc limits: " | |
| 1182 PTR_FORMAT "," PTR_FORMAT | |
| 1183 " (" SIZE_FORMAT "%%," SIZE_FORMAT "%%) ", | |
| 1184 _icms_start_limit, _icms_stop_limit, | |
| 1185 percent_of_space(eden, _icms_start_limit), | |
| 1186 percent_of_space(eden, _icms_stop_limit)); | |
| 1187 if (Verbose) { | |
| 1188 gclog_or_tty->print("eden: "); | |
| 1189 eden->print_on(gclog_or_tty); | |
| 1190 } | |
| 1191 } | |
| 1192 } | |
| 1193 | |
| 1194 // Any changes here should try to maintain the invariant | |
| 1195 // that if this method is called with _icms_start_limit | |
| 1196 // and _icms_stop_limit both NULL, then it should return NULL | |
| 1197 // and not notify the icms thread. | |
| 1198 HeapWord* | |
| 1199 CMSCollector::allocation_limit_reached(Space* space, HeapWord* top, | |
| 1200 size_t word_size) | |
| 1201 { | |
| 1202 // A start_limit equal to end() means the duty cycle is 0, so treat that as a | |
| 1203 // nop. | |
| 1204 if (CMSIncrementalMode && _icms_start_limit != space->end()) { | |
| 1205 if (top <= _icms_start_limit) { | |
| 1206 if (CMSTraceIncrementalMode) { | |
| 1207 space->print_on(gclog_or_tty); | |
| 1208 gclog_or_tty->stamp(); | |
| 1209 gclog_or_tty->print_cr(" start limit top=" PTR_FORMAT | |
| 1210 ", new limit=" PTR_FORMAT | |
| 1211 " (" SIZE_FORMAT "%%)", | |
| 1212 top, _icms_stop_limit, | |
| 1213 percent_of_space(space, _icms_stop_limit)); | |
| 1214 } | |
| 1215 ConcurrentMarkSweepThread::start_icms(); | |
| 1216 assert(top < _icms_stop_limit, "Tautology"); | |
| 1217 if (word_size < pointer_delta(_icms_stop_limit, top)) { | |
| 1218 return _icms_stop_limit; | |
| 1219 } | |
| 1220 | |
| 1221 // The allocation will cross both the _start and _stop limits, so do the | |
| 1222 // stop notification also and return end(). | |
| 1223 if (CMSTraceIncrementalMode) { | |
| 1224 space->print_on(gclog_or_tty); | |
| 1225 gclog_or_tty->stamp(); | |
| 1226 gclog_or_tty->print_cr(" +stop limit top=" PTR_FORMAT | |
| 1227 ", new limit=" PTR_FORMAT | |
| 1228 " (" SIZE_FORMAT "%%)", | |
| 1229 top, space->end(), | |
| 1230 percent_of_space(space, space->end())); | |
| 1231 } | |
| 1232 ConcurrentMarkSweepThread::stop_icms(); | |
| 1233 return space->end(); | |
| 1234 } | |
| 1235 | |
| 1236 if (top <= _icms_stop_limit) { | |
| 1237 if (CMSTraceIncrementalMode) { | |
| 1238 space->print_on(gclog_or_tty); | |
| 1239 gclog_or_tty->stamp(); | |
| 1240 gclog_or_tty->print_cr(" stop limit top=" PTR_FORMAT | |
| 1241 ", new limit=" PTR_FORMAT | |
| 1242 " (" SIZE_FORMAT "%%)", | |
| 1243 top, space->end(), | |
| 1244 percent_of_space(space, space->end())); | |
| 1245 } | |
| 1246 ConcurrentMarkSweepThread::stop_icms(); | |
| 1247 return space->end(); | |
| 1248 } | |
| 1249 | |
| 1250 if (CMSTraceIncrementalMode) { | |
| 1251 space->print_on(gclog_or_tty); | |
| 1252 gclog_or_tty->stamp(); | |
| 1253 gclog_or_tty->print_cr(" end limit top=" PTR_FORMAT | |
| 1254 ", new limit=" PTR_FORMAT, | |
| 1255 top, NULL); | |
| 1256 } | |
| 1257 } | |
| 1258 | |
| 1259 return NULL; | |
| 1260 } | |
| 1261 | |
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1262 oop ConcurrentMarkSweepGeneration::promote(oop obj, size_t obj_size) { |
| 0 | 1263 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in"); |
| 1264 // allocate, copy and if necessary update promoinfo -- | |
| 1265 // delegate to underlying space. | |
| 1266 assert_lock_strong(freelistLock()); | |
| 1267 | |
| 1268 #ifndef PRODUCT | |
| 1269 if (Universe::heap()->promotion_should_fail()) { | |
| 1270 return NULL; | |
| 1271 } | |
| 1272 #endif // #ifndef PRODUCT | |
| 1273 | |
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1274 oop res = _cmsSpace->promote(obj, obj_size); |
| 0 | 1275 if (res == NULL) { |
| 1276 // expand and retry | |
| 1277 size_t s = _cmsSpace->expansionSpaceRequired(obj_size); // HeapWords | |
| 1278 expand(s*HeapWordSize, MinHeapDeltaBytes, | |
| 1279 CMSExpansionCause::_satisfy_promotion); | |
| 1280 // Since there's currently no next generation, we don't try to promote | |
| 1281 // into a more senior generation. | |
| 1282 assert(next_gen() == NULL, "assumption, based upon which no attempt " | |
| 1283 "is made to pass on a possibly failing " | |
| 1284 "promotion to next generation"); | |
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1285 res = _cmsSpace->promote(obj, obj_size); |
| 0 | 1286 } |
| 1287 if (res != NULL) { | |
| 1288 // See comment in allocate() about when objects should | |
| 1289 // be allocated live. | |
| 1290 assert(obj->is_oop(), "Will dereference klass pointer below"); | |
| 1291 collector()->promoted(false, // Not parallel | |
| 1292 (HeapWord*)res, obj->is_objArray(), obj_size); | |
| 1293 // promotion counters | |
| 1294 NOT_PRODUCT( | |
| 1295 _numObjectsPromoted++; | |
| 1296 _numWordsPromoted += | |
| 1297 (int)(CompactibleFreeListSpace::adjustObjectSize(obj->size())); | |
| 1298 ) | |
| 1299 } | |
| 1300 return res; | |
| 1301 } | |
| 1302 | |
| 1303 | |
| 1304 HeapWord* | |
| 1305 ConcurrentMarkSweepGeneration::allocation_limit_reached(Space* space, | |
| 1306 HeapWord* top, | |
| 1307 size_t word_sz) | |
| 1308 { | |
| 1309 return collector()->allocation_limit_reached(space, top, word_sz); | |
| 1310 } | |
| 1311 | |
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1312 // IMPORTANT: Notes on object size recognition in CMS. |
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1313 // --------------------------------------------------- |
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1314 // A block of storage in the CMS generation is always in |
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1315 // one of three states. A free block (FREE), an allocated |
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1316 // object (OBJECT) whose size() method reports the correct size, |
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1317 // and an intermediate state (TRANSIENT) in which its size cannot |
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1318 // be accurately determined. |
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1319 // STATE IDENTIFICATION: (32 bit and 64 bit w/o COOPS) |
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1320 // ----------------------------------------------------- |
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1321 // FREE: klass_word & 1 == 1; mark_word holds block size |
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1322 // |
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1323 // OBJECT: klass_word installed; klass_word != 0 && klass_word & 1 == 0; |
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1324 // obj->size() computes correct size |
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1325 // |
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1326 // TRANSIENT: klass_word == 0; size is indeterminate until we become an OBJECT |
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1327 // |
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1328 // STATE IDENTIFICATION: (64 bit+COOPS) |
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1329 // ------------------------------------ |
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1330 // FREE: mark_word & CMS_FREE_BIT == 1; mark_word & ~CMS_FREE_BIT gives block_size |
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1331 // |
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1332 // OBJECT: klass_word installed; klass_word != 0; |
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1333 // obj->size() computes correct size |
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1334 // |
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1335 // TRANSIENT: klass_word == 0; size is indeterminate until we become an OBJECT |
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1336 // |
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1337 // |
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1338 // STATE TRANSITION DIAGRAM |
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1339 // |
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1340 // mut / parnew mut / parnew |
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1341 // FREE --------------------> TRANSIENT ---------------------> OBJECT --| |
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1342 // ^ | |
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1343 // |------------------------ DEAD <------------------------------------| |
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1344 // sweep mut |
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1345 // |
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1346 // While a block is in TRANSIENT state its size cannot be determined |
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1347 // so readers will either need to come back later or stall until |
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1348 // the size can be determined. Note that for the case of direct |
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1349 // allocation, P-bits, when available, may be used to determine the |
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1350 // size of an object that may not yet have been initialized. |
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1351 |
| 0 | 1352 // Things to support parallel young-gen collection. |
| 1353 oop | |
| 1354 ConcurrentMarkSweepGeneration::par_promote(int thread_num, | |
| 1355 oop old, markOop m, | |
| 1356 size_t word_sz) { | |
| 1357 #ifndef PRODUCT | |
| 1358 if (Universe::heap()->promotion_should_fail()) { | |
| 1359 return NULL; | |
| 1360 } | |
| 1361 #endif // #ifndef PRODUCT | |
| 1362 | |
| 1363 CMSParGCThreadState* ps = _par_gc_thread_states[thread_num]; | |
| 1364 PromotionInfo* promoInfo = &ps->promo; | |
| 1365 // if we are tracking promotions, then first ensure space for | |
| 1366 // promotion (including spooling space for saving header if necessary). | |
| 1367 // then allocate and copy, then track promoted info if needed. | |
| 1368 // When tracking (see PromotionInfo::track()), the mark word may | |
| 1369 // be displaced and in this case restoration of the mark word | |
| 1370 // occurs in the (oop_since_save_marks_)iterate phase. | |
| 1371 if (promoInfo->tracking() && !promoInfo->ensure_spooling_space()) { | |
| 1372 // Out of space for allocating spooling buffers; | |
| 1373 // try expanding and allocating spooling buffers. | |
| 1374 if (!expand_and_ensure_spooling_space(promoInfo)) { | |
| 1375 return NULL; | |
| 1376 } | |
| 1377 } | |
| 1378 assert(promoInfo->has_spooling_space(), "Control point invariant"); | |
|
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1379 const size_t alloc_sz = CompactibleFreeListSpace::adjustObjectSize(word_sz); |
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1380 HeapWord* obj_ptr = ps->lab.alloc(alloc_sz); |
| 0 | 1381 if (obj_ptr == NULL) { |
|
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1382 obj_ptr = expand_and_par_lab_allocate(ps, alloc_sz); |
| 0 | 1383 if (obj_ptr == NULL) { |
| 1384 return NULL; | |
| 1385 } | |
| 1386 } | |
| 1387 oop obj = oop(obj_ptr); | |
|
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1388 OrderAccess::storestore(); |
| 187 | 1389 assert(obj->klass_or_null() == NULL, "Object should be uninitialized here."); |
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1390 assert(!((FreeChunk*)obj_ptr)->is_free(), "Error, block will look free but show wrong size"); |
|
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1391 // IMPORTANT: See note on object initialization for CMS above. |
| 0 | 1392 // Otherwise, copy the object. Here we must be careful to insert the |
| 1393 // klass pointer last, since this marks the block as an allocated object. | |
| 187 | 1394 // Except with compressed oops it's the mark word. |
| 0 | 1395 HeapWord* old_ptr = (HeapWord*)old; |
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1396 // Restore the mark word copied above. |
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1397 obj->set_mark(m); |
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1398 assert(obj->klass_or_null() == NULL, "Object should be uninitialized here."); |
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1399 assert(!((FreeChunk*)obj_ptr)->is_free(), "Error, block will look free but show wrong size"); |
|
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1400 OrderAccess::storestore(); |
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1401 |
|
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1402 if (UseCompressedClassPointers) { |
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1403 // Copy gap missed by (aligned) header size calculation below |
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1404 obj->set_klass_gap(old->klass_gap()); |
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1405 } |
| 0 | 1406 if (word_sz > (size_t)oopDesc::header_size()) { |
| 1407 Copy::aligned_disjoint_words(old_ptr + oopDesc::header_size(), | |
| 1408 obj_ptr + oopDesc::header_size(), | |
| 1409 word_sz - oopDesc::header_size()); | |
| 1410 } | |
| 187 | 1411 |
| 0 | 1412 // Now we can track the promoted object, if necessary. We take care |
| 1521 | 1413 // to delay the transition from uninitialized to full object |
| 0 | 1414 // (i.e., insertion of klass pointer) until after, so that it |
| 1415 // atomically becomes a promoted object. | |
| 1416 if (promoInfo->tracking()) { | |
| 1417 promoInfo->track((PromotedObject*)obj, old->klass()); | |
| 1418 } | |
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1419 assert(obj->klass_or_null() == NULL, "Object should be uninitialized here."); |
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1420 assert(!((FreeChunk*)obj_ptr)->is_free(), "Error, block will look free but show wrong size"); |
|
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1421 assert(old->is_oop(), "Will use and dereference old klass ptr below"); |
| 187 | 1422 |
| 1423 // Finally, install the klass pointer (this should be volatile). | |
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1424 OrderAccess::storestore(); |
| 0 | 1425 obj->set_klass(old->klass()); |
|
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1426 // We should now be able to calculate the right size for this object |
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1427 assert(obj->is_oop() && obj->size() == (int)word_sz, "Error, incorrect size computed for promoted object"); |
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1428 |
| 0 | 1429 collector()->promoted(true, // parallel |
| 1430 obj_ptr, old->is_objArray(), word_sz); | |
| 1431 | |
| 1432 NOT_PRODUCT( | |
|
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1433 Atomic::inc_ptr(&_numObjectsPromoted); |
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1434 Atomic::add_ptr(alloc_sz, &_numWordsPromoted); |
| 0 | 1435 ) |
| 1436 | |
| 1437 return obj; | |
| 1438 } | |
| 1439 | |
| 1440 void | |
| 1441 ConcurrentMarkSweepGeneration:: | |
| 1442 par_promote_alloc_undo(int thread_num, | |
| 1443 HeapWord* obj, size_t word_sz) { | |
| 1444 // CMS does not support promotion undo. | |
| 1445 ShouldNotReachHere(); | |
| 1446 } | |
| 1447 | |
| 1448 void | |
| 1449 ConcurrentMarkSweepGeneration:: | |
| 1450 par_promote_alloc_done(int thread_num) { | |
| 1451 CMSParGCThreadState* ps = _par_gc_thread_states[thread_num]; | |
|
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1452 ps->lab.retire(thread_num); |
| 0 | 1453 } |
| 1454 | |
| 1455 void | |
| 1456 ConcurrentMarkSweepGeneration:: | |
| 1457 par_oop_since_save_marks_iterate_done(int thread_num) { | |
| 1458 CMSParGCThreadState* ps = _par_gc_thread_states[thread_num]; | |
| 1459 ParScanWithoutBarrierClosure* dummy_cl = NULL; | |
| 1460 ps->promo.promoted_oops_iterate_nv(dummy_cl); | |
| 1461 } | |
| 1462 | |
| 1463 bool ConcurrentMarkSweepGeneration::should_collect(bool full, | |
| 1464 size_t size, | |
| 1465 bool tlab) | |
| 1466 { | |
| 1467 // We allow a STW collection only if a full | |
| 1468 // collection was requested. | |
| 1469 return full || should_allocate(size, tlab); // FIX ME !!! | |
| 1470 // This and promotion failure handling are connected at the | |
| 1471 // hip and should be fixed by untying them. | |
| 1472 } | |
| 1473 | |
| 1474 bool CMSCollector::shouldConcurrentCollect() { | |
| 1475 if (_full_gc_requested) { | |
| 1476 if (Verbose && PrintGCDetails) { | |
| 1477 gclog_or_tty->print_cr("CMSCollector: collect because of explicit " | |
|
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1478 " gc request (or gc_locker)"); |
| 0 | 1479 } |
| 1480 return true; | |
| 1481 } | |
| 1482 | |
| 1483 // For debugging purposes, change the type of collection. | |
| 1484 // If the rotation is not on the concurrent collection | |
| 1485 // type, don't start a concurrent collection. | |
| 1486 NOT_PRODUCT( | |
| 1487 if (RotateCMSCollectionTypes && | |
| 1488 (_cmsGen->debug_collection_type() != | |
| 1489 ConcurrentMarkSweepGeneration::Concurrent_collection_type)) { | |
| 1490 assert(_cmsGen->debug_collection_type() != | |
| 1491 ConcurrentMarkSweepGeneration::Unknown_collection_type, | |
| 1492 "Bad cms collection type"); | |
| 1493 return false; | |
| 1494 } | |
| 1495 ) | |
| 1496 | |
| 1497 FreelistLocker x(this); | |
| 1498 // ------------------------------------------------------------------ | |
| 1499 // Print out lots of information which affects the initiation of | |
| 1500 // a collection. | |
| 1501 if (PrintCMSInitiationStatistics && stats().valid()) { | |
| 1502 gclog_or_tty->print("CMSCollector shouldConcurrentCollect: "); | |
| 1503 gclog_or_tty->stamp(); | |
| 1504 gclog_or_tty->print_cr(""); | |
| 1505 stats().print_on(gclog_or_tty); | |
| 1506 gclog_or_tty->print_cr("time_until_cms_gen_full %3.7f", | |
| 1507 stats().time_until_cms_gen_full()); | |
| 1508 gclog_or_tty->print_cr("free="SIZE_FORMAT, _cmsGen->free()); | |
| 1509 gclog_or_tty->print_cr("contiguous_available="SIZE_FORMAT, | |
| 1510 _cmsGen->contiguous_available()); | |
| 1511 gclog_or_tty->print_cr("promotion_rate=%g", stats().promotion_rate()); | |
| 1512 gclog_or_tty->print_cr("cms_allocation_rate=%g", stats().cms_allocation_rate()); | |
| 1513 gclog_or_tty->print_cr("occupancy=%3.7f", _cmsGen->occupancy()); | |
|
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1514 gclog_or_tty->print_cr("initiatingOccupancy=%3.7f", _cmsGen->initiating_occupancy()); |
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1515 gclog_or_tty->print_cr("metadata initialized %d", |
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1516 MetaspaceGC::should_concurrent_collect()); |
| 0 | 1517 } |
| 1518 // ------------------------------------------------------------------ | |
| 1519 | |
| 1520 // If the estimated time to complete a cms collection (cms_duration()) | |
| 1521 // is less than the estimated time remaining until the cms generation | |
| 1522 // is full, start a collection. | |
| 1523 if (!UseCMSInitiatingOccupancyOnly) { | |
| 1524 if (stats().valid()) { | |
| 1525 if (stats().time_until_cms_start() == 0.0) { | |
| 1526 return true; | |
| 1527 } | |
| 1528 } else { | |
| 1529 // We want to conservatively collect somewhat early in order | |
| 1530 // to try and "bootstrap" our CMS/promotion statistics; | |
| 1531 // this branch will not fire after the first successful CMS | |
| 1532 // collection because the stats should then be valid. | |
| 1533 if (_cmsGen->occupancy() >= _bootstrap_occupancy) { | |
| 1534 if (Verbose && PrintGCDetails) { | |
| 1535 gclog_or_tty->print_cr( | |
| 1536 " CMSCollector: collect for bootstrapping statistics:" | |
| 1537 " occupancy = %f, boot occupancy = %f", _cmsGen->occupancy(), | |
| 1538 _bootstrap_occupancy); | |
| 1539 } | |
| 1540 return true; | |
| 1541 } | |
| 1542 } | |
| 1543 } | |
| 1544 | |
|
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1545 // Otherwise, we start a collection cycle if |
| 0 | 1546 // old gen want a collection cycle started. Each may use |
| 1547 // an appropriate criterion for making this decision. | |
| 1548 // XXX We need to make sure that the gen expansion | |
|
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1549 // criterion dovetails well with this. XXX NEED TO FIX THIS |
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1550 if (_cmsGen->should_concurrent_collect()) { |
| 0 | 1551 if (Verbose && PrintGCDetails) { |
| 1552 gclog_or_tty->print_cr("CMS old gen initiated"); | |
| 1553 } | |
| 1554 return true; | |
| 1555 } | |
| 1556 | |
|
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1557 // We start a collection if we believe an incremental collection may fail; |
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1558 // this is not likely to be productive in practice because it's probably too |
|
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1559 // late anyway. |
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1560 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
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1561 assert(gch->collector_policy()->is_two_generation_policy(), |
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1562 "You may want to check the correctness of the following"); |
|
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1563 if (gch->incremental_collection_will_fail(true /* consult_young */)) { |
|
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1564 if (Verbose && PrintGCDetails) { |
|
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1565 gclog_or_tty->print("CMSCollector: collect because incremental collection will fail "); |
| 0 | 1566 } |
| 1567 return true; | |
| 1568 } | |
| 1569 | |
|
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1570 if (MetaspaceGC::should_concurrent_collect()) { |
|
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1571 if (Verbose && PrintGCDetails) { |
|
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1572 gclog_or_tty->print("CMSCollector: collect for metadata allocation "); |
|
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1573 } |
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1574 return true; |
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1575 } |
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1576 |
| 0 | 1577 return false; |
| 1578 } | |
| 1579 | |
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1580 void CMSCollector::set_did_compact(bool v) { _cmsGen->set_did_compact(v); } |
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1581 |
| 0 | 1582 // Clear _expansion_cause fields of constituent generations |
| 1583 void CMSCollector::clear_expansion_cause() { | |
| 1584 _cmsGen->clear_expansion_cause(); | |
| 1585 } | |
| 1586 | |
|
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1587 // We should be conservative in starting a collection cycle. To |
|
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1588 // start too eagerly runs the risk of collecting too often in the |
|
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1589 // extreme. To collect too rarely falls back on full collections, |
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1590 // which works, even if not optimum in terms of concurrent work. |
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1591 // As a work around for too eagerly collecting, use the flag |
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1592 // UseCMSInitiatingOccupancyOnly. This also has the advantage of |
|
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1593 // giving the user an easily understandable way of controlling the |
|
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1594 // collections. |
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1595 // We want to start a new collection cycle if any of the following |
|
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1596 // conditions hold: |
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1597 // . our current occupancy exceeds the configured initiating occupancy |
|
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1598 // for this generation, or |
|
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1599 // . we recently needed to expand this space and have not, since that |
|
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1600 // expansion, done a collection of this generation, or |
|
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1601 // . the underlying space believes that it may be a good idea to initiate |
|
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1602 // a concurrent collection (this may be based on criteria such as the |
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1603 // following: the space uses linear allocation and linear allocation is |
|
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1604 // going to fail, or there is believed to be excessive fragmentation in |
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1605 // the generation, etc... or ... |
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1606 // [.(currently done by CMSCollector::shouldConcurrentCollect() only for |
|
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1607 // the case of the old generation; see CR 6543076): |
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1608 // we may be approaching a point at which allocation requests may fail because |
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1609 // we will be out of sufficient free space given allocation rate estimates.] |
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1610 bool ConcurrentMarkSweepGeneration::should_concurrent_collect() const { |
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1611 |
| 0 | 1612 assert_lock_strong(freelistLock()); |
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1613 if (occupancy() > initiating_occupancy()) { |
| 0 | 1614 if (PrintGCDetails && Verbose) { |
| 1615 gclog_or_tty->print(" %s: collect because of occupancy %f / %f ", | |
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1616 short_name(), occupancy(), initiating_occupancy()); |
| 0 | 1617 } |
| 1618 return true; | |
| 1619 } | |
| 1620 if (UseCMSInitiatingOccupancyOnly) { | |
| 1621 return false; | |
| 1622 } | |
| 1623 if (expansion_cause() == CMSExpansionCause::_satisfy_allocation) { | |
| 1624 if (PrintGCDetails && Verbose) { | |
| 1625 gclog_or_tty->print(" %s: collect because expanded for allocation ", | |
| 1626 short_name()); | |
| 1627 } | |
| 1628 return true; | |
| 1629 } | |
|
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1630 if (_cmsSpace->should_concurrent_collect()) { |
| 0 | 1631 if (PrintGCDetails && Verbose) { |
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1632 gclog_or_tty->print(" %s: collect because cmsSpace says so ", |
| 0 | 1633 short_name()); |
| 1634 } | |
| 1635 return true; | |
| 1636 } | |
| 1637 return false; | |
| 1638 } | |
| 1639 | |
| 1640 void ConcurrentMarkSweepGeneration::collect(bool full, | |
| 1641 bool clear_all_soft_refs, | |
| 1642 size_t size, | |
| 1643 bool tlab) | |
| 1644 { | |
| 1645 collector()->collect(full, clear_all_soft_refs, size, tlab); | |
| 1646 } | |
| 1647 | |
| 1648 void CMSCollector::collect(bool full, | |
| 1649 bool clear_all_soft_refs, | |
| 1650 size_t size, | |
| 1651 bool tlab) | |
| 1652 { | |
| 1653 if (!UseCMSCollectionPassing && _collectorState > Idling) { | |
| 1654 // For debugging purposes skip the collection if the state | |
| 1655 // is not currently idle | |
| 1656 if (TraceCMSState) { | |
| 1657 gclog_or_tty->print_cr("Thread " INTPTR_FORMAT " skipped full:%d CMS state %d", | |
| 1658 Thread::current(), full, _collectorState); | |
| 1659 } | |
| 1660 return; | |
| 1661 } | |
| 1662 | |
| 1663 // The following "if" branch is present for defensive reasons. | |
| 1664 // In the current uses of this interface, it can be replaced with: | |
| 1665 // assert(!GC_locker.is_active(), "Can't be called otherwise"); | |
| 1666 // But I am not placing that assert here to allow future | |
| 1667 // generality in invoking this interface. | |
| 1668 if (GC_locker::is_active()) { | |
| 1669 // A consistency test for GC_locker | |
| 1670 assert(GC_locker::needs_gc(), "Should have been set already"); | |
| 1671 // Skip this foreground collection, instead | |
| 1672 // expanding the heap if necessary. | |
| 1673 // Need the free list locks for the call to free() in compute_new_size() | |
| 1674 compute_new_size(); | |
| 1675 return; | |
| 1676 } | |
| 1677 acquire_control_and_collect(full, clear_all_soft_refs); | |
| 1678 _full_gcs_since_conc_gc++; | |
| 1679 } | |
| 1680 | |
| 10405 | 1681 void CMSCollector::request_full_gc(unsigned int full_gc_count, GCCause::Cause cause) { |
| 0 | 1682 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
| 1683 unsigned int gc_count = gch->total_full_collections(); | |
| 1684 if (gc_count == full_gc_count) { | |
| 1685 MutexLockerEx y(CGC_lock, Mutex::_no_safepoint_check_flag); | |
| 1686 _full_gc_requested = true; | |
| 10405 | 1687 _full_gc_cause = cause; |
| 0 | 1688 CGC_lock->notify(); // nudge CMS thread |
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1689 } else { |
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1690 assert(gc_count > full_gc_count, "Error: causal loop"); |
| 0 | 1691 } |
| 1692 } | |
| 1693 | |
| 10405 | 1694 bool CMSCollector::is_external_interruption() { |
| 1695 GCCause::Cause cause = GenCollectedHeap::heap()->gc_cause(); | |
| 1696 return GCCause::is_user_requested_gc(cause) || | |
| 1697 GCCause::is_serviceability_requested_gc(cause); | |
| 1698 } | |
| 1699 | |
| 1700 void CMSCollector::report_concurrent_mode_interruption() { | |
| 1701 if (is_external_interruption()) { | |
| 1702 if (PrintGCDetails) { | |
| 1703 gclog_or_tty->print(" (concurrent mode interrupted)"); | |
| 1704 } | |
| 1705 } else { | |
| 1706 if (PrintGCDetails) { | |
| 1707 gclog_or_tty->print(" (concurrent mode failure)"); | |
| 1708 } | |
| 1709 _gc_tracer_cm->report_concurrent_mode_failure(); | |
| 1710 } | |
| 1711 } | |
| 1712 | |
| 0 | 1713 |
| 1714 // The foreground and background collectors need to coordinate in order | |
| 1715 // to make sure that they do not mutually interfere with CMS collections. | |
| 1716 // When a background collection is active, | |
| 1717 // the foreground collector may need to take over (preempt) and | |
| 1718 // synchronously complete an ongoing collection. Depending on the | |
| 1719 // frequency of the background collections and the heap usage | |
| 1720 // of the application, this preemption can be seldom or frequent. | |
| 1721 // There are only certain | |
| 1722 // points in the background collection that the "collection-baton" | |
| 1723 // can be passed to the foreground collector. | |
| 1724 // | |
| 1725 // The foreground collector will wait for the baton before | |
| 1726 // starting any part of the collection. The foreground collector | |
| 1727 // will only wait at one location. | |
| 1728 // | |
| 1729 // The background collector will yield the baton before starting a new | |
| 1730 // phase of the collection (e.g., before initial marking, marking from roots, | |
| 1731 // precleaning, final re-mark, sweep etc.) This is normally done at the head | |
| 1732 // of the loop which switches the phases. The background collector does some | |
| 1733 // of the phases (initial mark, final re-mark) with the world stopped. | |
| 1734 // Because of locking involved in stopping the world, | |
| 1735 // the foreground collector should not block waiting for the background | |
| 1736 // collector when it is doing a stop-the-world phase. The background | |
| 1737 // collector will yield the baton at an additional point just before | |
| 1738 // it enters a stop-the-world phase. Once the world is stopped, the | |
| 1739 // background collector checks the phase of the collection. If the | |
| 1740 // phase has not changed, it proceeds with the collection. If the | |
| 1741 // phase has changed, it skips that phase of the collection. See | |
| 1742 // the comments on the use of the Heap_lock in collect_in_background(). | |
| 1743 // | |
| 1744 // Variable used in baton passing. | |
| 1745 // _foregroundGCIsActive - Set to true by the foreground collector when | |
| 1746 // it wants the baton. The foreground clears it when it has finished | |
| 1747 // the collection. | |
| 1748 // _foregroundGCShouldWait - Set to true by the background collector | |
| 1749 // when it is running. The foreground collector waits while | |
| 1750 // _foregroundGCShouldWait is true. | |
| 1751 // CGC_lock - monitor used to protect access to the above variables | |
| 1752 // and to notify the foreground and background collectors. | |
| 1753 // _collectorState - current state of the CMS collection. | |
| 1754 // | |
| 1755 // The foreground collector | |
| 1756 // acquires the CGC_lock | |
| 1757 // sets _foregroundGCIsActive | |
| 1758 // waits on the CGC_lock for _foregroundGCShouldWait to be false | |
| 1759 // various locks acquired in preparation for the collection | |
| 1760 // are released so as not to block the background collector | |
| 1761 // that is in the midst of a collection | |
| 1762 // proceeds with the collection | |
| 1763 // clears _foregroundGCIsActive | |
| 1764 // returns | |
| 1765 // | |
| 1766 // The background collector in a loop iterating on the phases of the | |
| 1767 // collection | |
| 1768 // acquires the CGC_lock | |
| 1769 // sets _foregroundGCShouldWait | |
| 1770 // if _foregroundGCIsActive is set | |
| 1771 // clears _foregroundGCShouldWait, notifies _CGC_lock | |
| 1772 // waits on _CGC_lock for _foregroundGCIsActive to become false | |
| 1773 // and exits the loop. | |
| 1774 // otherwise | |
| 1775 // proceed with that phase of the collection | |
| 1776 // if the phase is a stop-the-world phase, | |
| 1777 // yield the baton once more just before enqueueing | |
| 1778 // the stop-world CMS operation (executed by the VM thread). | |
| 1779 // returns after all phases of the collection are done | |
| 1780 // | |
| 1781 | |
| 1782 void CMSCollector::acquire_control_and_collect(bool full, | |
| 1783 bool clear_all_soft_refs) { | |
| 1784 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); | |
| 1785 assert(!Thread::current()->is_ConcurrentGC_thread(), | |
| 1786 "shouldn't try to acquire control from self!"); | |
| 1787 | |
| 1788 // Start the protocol for acquiring control of the | |
| 1789 // collection from the background collector (aka CMS thread). | |
| 1790 assert(ConcurrentMarkSweepThread::vm_thread_has_cms_token(), | |
| 1791 "VM thread should have CMS token"); | |
| 1792 // Remember the possibly interrupted state of an ongoing | |
| 1793 // concurrent collection | |
| 1794 CollectorState first_state = _collectorState; | |
| 1795 | |
| 1796 // Signal to a possibly ongoing concurrent collection that | |
| 1797 // we want to do a foreground collection. | |
| 1798 _foregroundGCIsActive = true; | |
| 1799 | |
| 1800 // Disable incremental mode during a foreground collection. | |
| 1801 ICMSDisabler icms_disabler; | |
| 1802 | |
| 1803 // release locks and wait for a notify from the background collector | |
| 1804 // releasing the locks in only necessary for phases which | |
| 1805 // do yields to improve the granularity of the collection. | |
| 1806 assert_lock_strong(bitMapLock()); | |
| 1807 // We need to lock the Free list lock for the space that we are | |
| 1808 // currently collecting. | |
| 1809 assert(haveFreelistLocks(), "Must be holding free list locks"); | |
| 1810 bitMapLock()->unlock(); | |
| 1811 releaseFreelistLocks(); | |
| 1812 { | |
| 1813 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
| 1814 if (_foregroundGCShouldWait) { | |
| 1815 // We are going to be waiting for action for the CMS thread; | |
| 1816 // it had better not be gone (for instance at shutdown)! | |
| 1817 assert(ConcurrentMarkSweepThread::cmst() != NULL, | |
| 1818 "CMS thread must be running"); | |
| 1819 // Wait here until the background collector gives us the go-ahead | |
| 1820 ConcurrentMarkSweepThread::clear_CMS_flag( | |
| 1821 ConcurrentMarkSweepThread::CMS_vm_has_token); // release token | |
| 1822 // Get a possibly blocked CMS thread going: | |
| 1823 // Note that we set _foregroundGCIsActive true above, | |
| 1824 // without protection of the CGC_lock. | |
| 1825 CGC_lock->notify(); | |
| 1826 assert(!ConcurrentMarkSweepThread::vm_thread_wants_cms_token(), | |
| 1827 "Possible deadlock"); | |
| 1828 while (_foregroundGCShouldWait) { | |
| 1829 // wait for notification | |
| 1830 CGC_lock->wait(Mutex::_no_safepoint_check_flag); | |
| 1831 // Possibility of delay/starvation here, since CMS token does | |
| 1832 // not know to give priority to VM thread? Actually, i think | |
| 1833 // there wouldn't be any delay/starvation, but the proof of | |
| 1834 // that "fact" (?) appears non-trivial. XXX 20011219YSR | |
| 1835 } | |
| 1836 ConcurrentMarkSweepThread::set_CMS_flag( | |
| 1837 ConcurrentMarkSweepThread::CMS_vm_has_token); | |
| 1838 } | |
| 1839 } | |
| 1840 // The CMS_token is already held. Get back the other locks. | |
| 1841 assert(ConcurrentMarkSweepThread::vm_thread_has_cms_token(), | |
| 1842 "VM thread should have CMS token"); | |
| 1843 getFreelistLocks(); | |
| 1844 bitMapLock()->lock_without_safepoint_check(); | |
| 1845 if (TraceCMSState) { | |
| 1846 gclog_or_tty->print_cr("CMS foreground collector has asked for control " | |
| 1847 INTPTR_FORMAT " with first state %d", Thread::current(), first_state); | |
| 1848 gclog_or_tty->print_cr(" gets control with state %d", _collectorState); | |
| 1849 } | |
| 1850 | |
| 1851 // Check if we need to do a compaction, or if not, whether | |
| 1852 // we need to start the mark-sweep from scratch. | |
| 1853 bool should_compact = false; | |
| 1854 bool should_start_over = false; | |
| 1855 decide_foreground_collection_type(clear_all_soft_refs, | |
| 1856 &should_compact, &should_start_over); | |
| 1857 | |
| 1858 NOT_PRODUCT( | |
| 1859 if (RotateCMSCollectionTypes) { | |
| 1860 if (_cmsGen->debug_collection_type() == | |
| 1861 ConcurrentMarkSweepGeneration::MSC_foreground_collection_type) { | |
| 1862 should_compact = true; | |
| 1863 } else if (_cmsGen->debug_collection_type() == | |
| 1864 ConcurrentMarkSweepGeneration::MS_foreground_collection_type) { | |
| 1865 should_compact = false; | |
| 1866 } | |
| 1867 } | |
| 1868 ) | |
| 1869 | |
| 10405 | 1870 if (first_state > Idling) { |
| 1871 report_concurrent_mode_interruption(); | |
| 0 | 1872 } |
| 1873 | |
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1874 set_did_compact(should_compact); |
| 0 | 1875 if (should_compact) { |
| 1876 // If the collection is being acquired from the background | |
| 1877 // collector, there may be references on the discovered | |
| 1878 // references lists that have NULL referents (being those | |
| 1879 // that were concurrently cleared by a mutator) or | |
| 1880 // that are no longer active (having been enqueued concurrently | |
| 1881 // by the mutator). | |
| 1882 // Scrub the list of those references because Mark-Sweep-Compact | |
| 1883 // code assumes referents are not NULL and that all discovered | |
| 1884 // Reference objects are active. | |
| 1885 ref_processor()->clean_up_discovered_references(); | |
| 1886 | |
| 10405 | 1887 if (first_state > Idling) { |
| 1888 save_heap_summary(); | |
| 1889 } | |
| 1890 | |
| 0 | 1891 do_compaction_work(clear_all_soft_refs); |
| 1892 | |
| 1893 // Has the GC time limit been exceeded? | |
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1894 DefNewGeneration* young_gen = _young_gen->as_DefNewGeneration(); |
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1895 size_t max_eden_size = young_gen->max_capacity() - |
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1896 young_gen->to()->capacity() - |
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1897 young_gen->from()->capacity(); |
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1898 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
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1899 GCCause::Cause gc_cause = gch->gc_cause(); |
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1900 size_policy()->check_gc_overhead_limit(_young_gen->used(), |
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1901 young_gen->eden()->used(), |
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1902 _cmsGen->max_capacity(), |
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1903 max_eden_size, |
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1904 full, |
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1905 gc_cause, |
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1906 gch->collector_policy()); |
| 0 | 1907 } else { |
| 1908 do_mark_sweep_work(clear_all_soft_refs, first_state, | |
| 1909 should_start_over); | |
| 1910 } | |
| 1911 // Reset the expansion cause, now that we just completed | |
| 1912 // a collection cycle. | |
| 1913 clear_expansion_cause(); | |
| 1914 _foregroundGCIsActive = false; | |
| 1915 return; | |
| 1916 } | |
| 1917 | |
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1918 // Resize the tenured generation |
| 0 | 1919 // after obtaining the free list locks for the |
| 1920 // two generations. | |
| 1921 void CMSCollector::compute_new_size() { | |
| 1922 assert_locked_or_safepoint(Heap_lock); | |
| 1923 FreelistLocker z(this); | |
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1924 MetaspaceGC::compute_new_size(); |
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1925 _cmsGen->compute_new_size_free_list(); |
| 0 | 1926 } |
| 1927 | |
| 1928 // A work method used by foreground collection to determine | |
| 1929 // what type of collection (compacting or not, continuing or fresh) | |
| 1930 // it should do. | |
| 1931 // NOTE: the intent is to make UseCMSCompactAtFullCollection | |
| 1932 // and CMSCompactWhenClearAllSoftRefs the default in the future | |
| 1933 // and do away with the flags after a suitable period. | |
| 1934 void CMSCollector::decide_foreground_collection_type( | |
| 1935 bool clear_all_soft_refs, bool* should_compact, | |
| 1936 bool* should_start_over) { | |
| 1937 // Normally, we'll compact only if the UseCMSCompactAtFullCollection | |
| 1938 // flag is set, and we have either requested a System.gc() or | |
| 1939 // the number of full gc's since the last concurrent cycle | |
| 1940 // has exceeded the threshold set by CMSFullGCsBeforeCompaction, | |
| 1941 // or if an incremental collection has failed | |
| 1942 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 1943 assert(gch->collector_policy()->is_two_generation_policy(), | |
| 1944 "You may want to check the correctness of the following"); | |
| 1945 // Inform cms gen if this was due to partial collection failing. | |
| 1946 // The CMS gen may use this fact to determine its expansion policy. | |
|
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1947 if (gch->incremental_collection_will_fail(false /* don't consult_young */)) { |
| 0 | 1948 assert(!_cmsGen->incremental_collection_failed(), |
| 1949 "Should have been noticed, reacted to and cleared"); | |
| 1950 _cmsGen->set_incremental_collection_failed(); | |
| 1951 } | |
| 1952 *should_compact = | |
| 1953 UseCMSCompactAtFullCollection && | |
| 1954 ((_full_gcs_since_conc_gc >= CMSFullGCsBeforeCompaction) || | |
| 1955 GCCause::is_user_requested_gc(gch->gc_cause()) || | |
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1956 gch->incremental_collection_will_fail(true /* consult_young */)); |
| 0 | 1957 *should_start_over = false; |
| 1958 if (clear_all_soft_refs && !*should_compact) { | |
| 1959 // We are about to do a last ditch collection attempt | |
| 1960 // so it would normally make sense to do a compaction | |
| 1961 // to reclaim as much space as possible. | |
| 1962 if (CMSCompactWhenClearAllSoftRefs) { | |
| 1963 // Default: The rationale is that in this case either | |
| 1964 // we are past the final marking phase, in which case | |
| 1965 // we'd have to start over, or so little has been done | |
| 1966 // that there's little point in saving that work. Compaction | |
| 1967 // appears to be the sensible choice in either case. | |
| 1968 *should_compact = true; | |
| 1969 } else { | |
| 1970 // We have been asked to clear all soft refs, but not to | |
| 1971 // compact. Make sure that we aren't past the final checkpoint | |
| 1972 // phase, for that is where we process soft refs. If we are already | |
| 1973 // past that phase, we'll need to redo the refs discovery phase and | |
| 1974 // if necessary clear soft refs that weren't previously | |
| 1975 // cleared. We do so by remembering the phase in which | |
| 1976 // we came in, and if we are past the refs processing | |
| 1977 // phase, we'll choose to just redo the mark-sweep | |
| 1978 // collection from scratch. | |
| 1979 if (_collectorState > FinalMarking) { | |
| 1980 // We are past the refs processing phase; | |
| 1981 // start over and do a fresh synchronous CMS cycle | |
| 1982 _collectorState = Resetting; // skip to reset to start new cycle | |
| 1983 reset(false /* == !asynch */); | |
| 1984 *should_start_over = true; | |
| 1985 } // else we can continue a possibly ongoing current cycle | |
| 1986 } | |
| 1987 } | |
| 1988 } | |
| 1989 | |
| 1990 // A work method used by the foreground collector to do | |
| 1991 // a mark-sweep-compact. | |
| 1992 void CMSCollector::do_compaction_work(bool clear_all_soft_refs) { | |
| 1993 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 10405 | 1994 |
| 1995 STWGCTimer* gc_timer = GenMarkSweep::gc_timer(); | |
|
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1996 gc_timer->register_gc_start(); |
| 10405 | 1997 |
| 1998 SerialOldTracer* gc_tracer = GenMarkSweep::gc_tracer(); | |
| 1999 gc_tracer->report_gc_start(gch->gc_cause(), gc_timer->gc_start()); | |
| 2000 | |
| 2001 GCTraceTime t("CMS:MSC ", PrintGCDetails && Verbose, true, NULL); | |
| 0 | 2002 if (PrintGC && Verbose && !(GCCause::is_user_requested_gc(gch->gc_cause()))) { |
| 2003 gclog_or_tty->print_cr("Compact ConcurrentMarkSweepGeneration after %d " | |
| 2004 "collections passed to foreground collector", _full_gcs_since_conc_gc); | |
| 2005 } | |
| 2006 | |
| 2007 // Sample collection interval time and reset for collection pause. | |
| 2008 if (UseAdaptiveSizePolicy) { | |
| 2009 size_policy()->msc_collection_begin(); | |
| 2010 } | |
| 2011 | |
| 2012 // Temporarily widen the span of the weak reference processing to | |
| 2013 // the entire heap. | |
| 2014 MemRegion new_span(GenCollectedHeap::heap()->reserved_region()); | |
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2015 ReferenceProcessorSpanMutator rp_mut_span(ref_processor(), new_span); |
| 0 | 2016 // Temporarily, clear the "is_alive_non_header" field of the |
| 2017 // reference processor. | |
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2018 ReferenceProcessorIsAliveMutator rp_mut_closure(ref_processor(), NULL); |
| 0 | 2019 // Temporarily make reference _processing_ single threaded (non-MT). |
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2020 ReferenceProcessorMTProcMutator rp_mut_mt_processing(ref_processor(), false); |
| 0 | 2021 // Temporarily make refs discovery atomic |
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2022 ReferenceProcessorAtomicMutator rp_mut_atomic(ref_processor(), true); |
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2023 // Temporarily make reference _discovery_ single threaded (non-MT) |
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2024 ReferenceProcessorMTDiscoveryMutator rp_mut_discovery(ref_processor(), false); |
| 0 | 2025 |
| 2026 ref_processor()->set_enqueuing_is_done(false); | |
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2027 ref_processor()->enable_discovery(false /*verify_disabled*/, false /*check_no_refs*/); |
|
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2028 ref_processor()->setup_policy(clear_all_soft_refs); |
| 0 | 2029 // If an asynchronous collection finishes, the _modUnionTable is |
| 2030 // all clear. If we are assuming the collection from an asynchronous | |
| 2031 // collection, clear the _modUnionTable. | |
| 2032 assert(_collectorState != Idling || _modUnionTable.isAllClear(), | |
| 2033 "_modUnionTable should be clear if the baton was not passed"); | |
| 2034 _modUnionTable.clear_all(); | |
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2035 assert(_collectorState != Idling || _ct->klass_rem_set()->mod_union_is_clear(), |
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2036 "mod union for klasses should be clear if the baton was passed"); |
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2037 _ct->klass_rem_set()->clear_mod_union(); |
| 0 | 2038 |
| 2039 // We must adjust the allocation statistics being maintained | |
| 2040 // in the free list space. We do so by reading and clearing | |
| 2041 // the sweep timer and updating the block flux rate estimates below. | |
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2042 assert(!_intra_sweep_timer.is_active(), "_intra_sweep_timer should be inactive"); |
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2043 if (_inter_sweep_timer.is_active()) { |
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2044 _inter_sweep_timer.stop(); |
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2045 // Note that we do not use this sample to update the _inter_sweep_estimate. |
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2046 _cmsGen->cmsSpace()->beginSweepFLCensus((float)(_inter_sweep_timer.seconds()), |
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2047 _inter_sweep_estimate.padded_average(), |
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2048 _intra_sweep_estimate.padded_average()); |
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2049 } |
| 0 | 2050 |
| 2051 GenMarkSweep::invoke_at_safepoint(_cmsGen->level(), | |
| 2052 ref_processor(), clear_all_soft_refs); | |
| 2053 #ifdef ASSERT | |
| 2054 CompactibleFreeListSpace* cms_space = _cmsGen->cmsSpace(); | |
| 2055 size_t free_size = cms_space->free(); | |
| 2056 assert(free_size == | |
| 2057 pointer_delta(cms_space->end(), cms_space->compaction_top()) | |
| 2058 * HeapWordSize, | |
| 2059 "All the free space should be compacted into one chunk at top"); | |
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2060 assert(cms_space->dictionary()->total_chunk_size( |
| 0 | 2061 debug_only(cms_space->freelistLock())) == 0 || |
| 2062 cms_space->totalSizeInIndexedFreeLists() == 0, | |
| 2063 "All the free space should be in a single chunk"); | |
| 2064 size_t num = cms_space->totalCount(); | |
| 2065 assert((free_size == 0 && num == 0) || | |
| 2066 (free_size > 0 && (num == 1 || num == 2)), | |
| 2067 "There should be at most 2 free chunks after compaction"); | |
| 2068 #endif // ASSERT | |
| 2069 _collectorState = Resetting; | |
| 2070 assert(_restart_addr == NULL, | |
| 2071 "Should have been NULL'd before baton was passed"); | |
| 2072 reset(false /* == !asynch */); | |
| 2073 _cmsGen->reset_after_compaction(); | |
|
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2074 _concurrent_cycles_since_last_unload = 0; |
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2075 |
| 0 | 2076 // Clear any data recorded in the PLAB chunk arrays. |
| 2077 if (_survivor_plab_array != NULL) { | |
| 2078 reset_survivor_plab_arrays(); | |
| 2079 } | |
| 2080 | |
| 2081 // Adjust the per-size allocation stats for the next epoch. | |
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2082 _cmsGen->cmsSpace()->endSweepFLCensus(sweep_count() /* fake */); |
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2083 // Restart the "inter sweep timer" for the next epoch. |
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2084 _inter_sweep_timer.reset(); |
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2085 _inter_sweep_timer.start(); |
| 0 | 2086 |
| 2087 // Sample collection pause time and reset for collection interval. | |
| 2088 if (UseAdaptiveSizePolicy) { | |
| 2089 size_policy()->msc_collection_end(gch->gc_cause()); | |
| 2090 } | |
| 2091 | |
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2092 gc_timer->register_gc_end(); |
| 10405 | 2093 |
| 2094 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); | |
| 2095 | |
| 0 | 2096 // For a mark-sweep-compact, compute_new_size() will be called |
| 2097 // in the heap's do_collection() method. | |
| 2098 } | |
| 2099 | |
| 2100 // A work method used by the foreground collector to do | |
| 2101 // a mark-sweep, after taking over from a possibly on-going | |
| 2102 // concurrent mark-sweep collection. | |
| 2103 void CMSCollector::do_mark_sweep_work(bool clear_all_soft_refs, | |
| 2104 CollectorState first_state, bool should_start_over) { | |
| 2105 if (PrintGC && Verbose) { | |
| 2106 gclog_or_tty->print_cr("Pass concurrent collection to foreground " | |
| 2107 "collector with count %d", | |
| 2108 _full_gcs_since_conc_gc); | |
| 2109 } | |
| 2110 switch (_collectorState) { | |
| 2111 case Idling: | |
| 2112 if (first_state == Idling || should_start_over) { | |
| 2113 // The background GC was not active, or should | |
| 2114 // restarted from scratch; start the cycle. | |
| 2115 _collectorState = InitialMarking; | |
| 2116 } | |
| 2117 // If first_state was not Idling, then a background GC | |
| 2118 // was in progress and has now finished. No need to do it | |
| 2119 // again. Leave the state as Idling. | |
| 2120 break; | |
| 2121 case Precleaning: | |
| 2122 // In the foreground case don't do the precleaning since | |
| 2123 // it is not done concurrently and there is extra work | |
| 2124 // required. | |
| 2125 _collectorState = FinalMarking; | |
| 2126 } | |
| 10405 | 2127 collect_in_foreground(clear_all_soft_refs, GenCollectedHeap::heap()->gc_cause()); |
| 0 | 2128 |
| 2129 // For a mark-sweep, compute_new_size() will be called | |
| 2130 // in the heap's do_collection() method. | |
| 2131 } | |
| 2132 | |
| 2133 | |
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2134 void CMSCollector::print_eden_and_survivor_chunk_arrays() { |
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2135 DefNewGeneration* dng = _young_gen->as_DefNewGeneration(); |
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2136 EdenSpace* eden_space = dng->eden(); |
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2137 ContiguousSpace* from_space = dng->from(); |
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2138 ContiguousSpace* to_space = dng->to(); |
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2139 // Eden |
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2140 if (_eden_chunk_array != NULL) { |
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2141 gclog_or_tty->print_cr("eden " PTR_FORMAT "-" PTR_FORMAT "-" PTR_FORMAT "(" SIZE_FORMAT ")", |
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2142 eden_space->bottom(), eden_space->top(), |
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2143 eden_space->end(), eden_space->capacity()); |
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2144 gclog_or_tty->print_cr("_eden_chunk_index=" SIZE_FORMAT ", " |
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2145 "_eden_chunk_capacity=" SIZE_FORMAT, |
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2146 _eden_chunk_index, _eden_chunk_capacity); |
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2147 for (size_t i = 0; i < _eden_chunk_index; i++) { |
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2148 gclog_or_tty->print_cr("_eden_chunk_array[" SIZE_FORMAT "]=" PTR_FORMAT, |
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2149 i, _eden_chunk_array[i]); |
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2150 } |
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2151 } |
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2152 // Survivor |
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2153 if (_survivor_chunk_array != NULL) { |
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2154 gclog_or_tty->print_cr("survivor " PTR_FORMAT "-" PTR_FORMAT "-" PTR_FORMAT "(" SIZE_FORMAT ")", |
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2155 from_space->bottom(), from_space->top(), |
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2156 from_space->end(), from_space->capacity()); |
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2157 gclog_or_tty->print_cr("_survivor_chunk_index=" SIZE_FORMAT ", " |
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2158 "_survivor_chunk_capacity=" SIZE_FORMAT, |
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2159 _survivor_chunk_index, _survivor_chunk_capacity); |
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2160 for (size_t i = 0; i < _survivor_chunk_index; i++) { |
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2161 gclog_or_tty->print_cr("_survivor_chunk_array[" SIZE_FORMAT "]=" PTR_FORMAT, |
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2162 i, _survivor_chunk_array[i]); |
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2163 } |
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2164 } |
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2165 } |
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2166 |
| 0 | 2167 void CMSCollector::getFreelistLocks() const { |
| 2168 // Get locks for all free lists in all generations that this | |
| 2169 // collector is responsible for | |
| 2170 _cmsGen->freelistLock()->lock_without_safepoint_check(); | |
| 2171 } | |
| 2172 | |
| 2173 void CMSCollector::releaseFreelistLocks() const { | |
| 2174 // Release locks for all free lists in all generations that this | |
| 2175 // collector is responsible for | |
| 2176 _cmsGen->freelistLock()->unlock(); | |
| 2177 } | |
| 2178 | |
| 2179 bool CMSCollector::haveFreelistLocks() const { | |
| 2180 // Check locks for all free lists in all generations that this | |
| 2181 // collector is responsible for | |
| 2182 assert_lock_strong(_cmsGen->freelistLock()); | |
| 2183 PRODUCT_ONLY(ShouldNotReachHere()); | |
| 2184 return true; | |
| 2185 } | |
| 2186 | |
| 2187 // A utility class that is used by the CMS collector to | |
| 2188 // temporarily "release" the foreground collector from its | |
| 2189 // usual obligation to wait for the background collector to | |
| 2190 // complete an ongoing phase before proceeding. | |
| 2191 class ReleaseForegroundGC: public StackObj { | |
| 2192 private: | |
| 2193 CMSCollector* _c; | |
| 2194 public: | |
| 2195 ReleaseForegroundGC(CMSCollector* c) : _c(c) { | |
| 2196 assert(_c->_foregroundGCShouldWait, "Else should not need to call"); | |
| 2197 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
| 2198 // allow a potentially blocked foreground collector to proceed | |
| 2199 _c->_foregroundGCShouldWait = false; | |
| 2200 if (_c->_foregroundGCIsActive) { | |
| 2201 CGC_lock->notify(); | |
| 2202 } | |
| 2203 assert(!ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 2204 "Possible deadlock"); | |
| 2205 } | |
| 2206 | |
| 2207 ~ReleaseForegroundGC() { | |
| 2208 assert(!_c->_foregroundGCShouldWait, "Usage protocol violation?"); | |
| 2209 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
| 2210 _c->_foregroundGCShouldWait = true; | |
| 2211 } | |
| 2212 }; | |
| 2213 | |
| 2214 // There are separate collect_in_background and collect_in_foreground because of | |
| 2215 // the different locking requirements of the background collector and the | |
| 2216 // foreground collector. There was originally an attempt to share | |
| 2217 // one "collect" method between the background collector and the foreground | |
| 2218 // collector but the if-then-else required made it cleaner to have | |
| 2219 // separate methods. | |
| 10405 | 2220 void CMSCollector::collect_in_background(bool clear_all_soft_refs, GCCause::Cause cause) { |
| 0 | 2221 assert(Thread::current()->is_ConcurrentGC_thread(), |
| 2222 "A CMS asynchronous collection is only allowed on a CMS thread."); | |
| 2223 | |
| 2224 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 2225 { | |
| 2226 bool safepoint_check = Mutex::_no_safepoint_check_flag; | |
| 2227 MutexLockerEx hl(Heap_lock, safepoint_check); | |
|
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2228 FreelistLocker fll(this); |
| 0 | 2229 MutexLockerEx x(CGC_lock, safepoint_check); |
| 2230 if (_foregroundGCIsActive || !UseAsyncConcMarkSweepGC) { | |
| 2231 // The foreground collector is active or we're | |
| 2232 // not using asynchronous collections. Skip this | |
| 2233 // background collection. | |
| 2234 assert(!_foregroundGCShouldWait, "Should be clear"); | |
| 2235 return; | |
| 2236 } else { | |
| 2237 assert(_collectorState == Idling, "Should be idling before start."); | |
| 2238 _collectorState = InitialMarking; | |
| 10405 | 2239 register_gc_start(cause); |
| 0 | 2240 // Reset the expansion cause, now that we are about to begin |
| 2241 // a new cycle. | |
| 2242 clear_expansion_cause(); | |
|
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2243 |
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2244 // Clear the MetaspaceGC flag since a concurrent collection |
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2245 // is starting but also clear it after the collection. |
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2246 MetaspaceGC::set_should_concurrent_collect(false); |
| 0 | 2247 } |
|
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2248 // Decide if we want to enable class unloading as part of the |
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2249 // ensuing concurrent GC cycle. |
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|
2250 update_should_unload_classes(); |
| 0 | 2251 _full_gc_requested = false; // acks all outstanding full gc requests |
| 10405 | 2252 _full_gc_cause = GCCause::_no_gc; |
| 0 | 2253 // Signal that we are about to start a collection |
| 2254 gch->increment_total_full_collections(); // ... starting a collection cycle | |
| 2255 _collection_count_start = gch->total_full_collections(); | |
| 2256 } | |
| 2257 | |
| 2258 // Used for PrintGC | |
| 2259 size_t prev_used; | |
| 2260 if (PrintGC && Verbose) { | |
| 2261 prev_used = _cmsGen->used(); // XXXPERM | |
| 2262 } | |
| 2263 | |
| 2264 // The change of the collection state is normally done at this level; | |
| 2265 // the exceptions are phases that are executed while the world is | |
| 2266 // stopped. For those phases the change of state is done while the | |
| 2267 // world is stopped. For baton passing purposes this allows the | |
| 2268 // background collector to finish the phase and change state atomically. | |
| 2269 // The foreground collector cannot wait on a phase that is done | |
| 2270 // while the world is stopped because the foreground collector already | |
| 2271 // has the world stopped and would deadlock. | |
| 2272 while (_collectorState != Idling) { | |
| 2273 if (TraceCMSState) { | |
| 2274 gclog_or_tty->print_cr("Thread " INTPTR_FORMAT " in CMS state %d", | |
| 2275 Thread::current(), _collectorState); | |
| 2276 } | |
| 2277 // The foreground collector | |
| 2278 // holds the Heap_lock throughout its collection. | |
| 2279 // holds the CMS token (but not the lock) | |
| 2280 // except while it is waiting for the background collector to yield. | |
| 2281 // | |
| 2282 // The foreground collector should be blocked (not for long) | |
| 2283 // if the background collector is about to start a phase | |
| 2284 // executed with world stopped. If the background | |
| 2285 // collector has already started such a phase, the | |
| 2286 // foreground collector is blocked waiting for the | |
| 2287 // Heap_lock. The stop-world phases (InitialMarking and FinalMarking) | |
| 2288 // are executed in the VM thread. | |
| 2289 // | |
| 2290 // The locking order is | |
| 2291 // PendingListLock (PLL) -- if applicable (FinalMarking) | |
| 2292 // Heap_lock (both this & PLL locked in VM_CMS_Operation::prologue()) | |
| 2293 // CMS token (claimed in | |
| 2294 // stop_world_and_do() --> | |
| 2295 // safepoint_synchronize() --> | |
| 2296 // CMSThread::synchronize()) | |
| 2297 | |
| 2298 { | |
| 2299 // Check if the FG collector wants us to yield. | |
| 2300 CMSTokenSync x(true); // is cms thread | |
| 2301 if (waitForForegroundGC()) { | |
| 2302 // We yielded to a foreground GC, nothing more to be | |
| 2303 // done this round. | |
| 2304 assert(_foregroundGCShouldWait == false, "We set it to false in " | |
| 2305 "waitForForegroundGC()"); | |
| 2306 if (TraceCMSState) { | |
| 2307 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT | |
| 2308 " exiting collection CMS state %d", | |
| 2309 Thread::current(), _collectorState); | |
| 2310 } | |
| 2311 return; | |
| 2312 } else { | |
| 2313 // The background collector can run but check to see if the | |
| 2314 // foreground collector has done a collection while the | |
| 2315 // background collector was waiting to get the CGC_lock | |
| 2316 // above. If yes, break so that _foregroundGCShouldWait | |
| 2317 // is cleared before returning. | |
| 2318 if (_collectorState == Idling) { | |
| 2319 break; | |
| 2320 } | |
| 2321 } | |
| 2322 } | |
| 2323 | |
| 2324 assert(_foregroundGCShouldWait, "Foreground collector, if active, " | |
| 2325 "should be waiting"); | |
| 2326 | |
| 2327 switch (_collectorState) { | |
| 2328 case InitialMarking: | |
| 2329 { | |
| 2330 ReleaseForegroundGC x(this); | |
| 2331 stats().record_cms_begin(); | |
| 2332 VM_CMS_Initial_Mark initial_mark_op(this); | |
| 2333 VMThread::execute(&initial_mark_op); | |
| 2334 } | |
| 2335 // The collector state may be any legal state at this point | |
| 2336 // since the background collector may have yielded to the | |
| 2337 // foreground collector. | |
| 2338 break; | |
| 2339 case Marking: | |
| 2340 // initial marking in checkpointRootsInitialWork has been completed | |
| 2341 if (markFromRoots(true)) { // we were successful | |
| 2342 assert(_collectorState == Precleaning, "Collector state should " | |
| 2343 "have changed"); | |
| 2344 } else { | |
| 2345 assert(_foregroundGCIsActive, "Internal state inconsistency"); | |
| 2346 } | |
| 2347 break; | |
| 2348 case Precleaning: | |
| 2349 if (UseAdaptiveSizePolicy) { | |
| 2350 size_policy()->concurrent_precleaning_begin(); | |
| 2351 } | |
| 2352 // marking from roots in markFromRoots has been completed | |
| 2353 preclean(); | |
| 2354 if (UseAdaptiveSizePolicy) { | |
| 2355 size_policy()->concurrent_precleaning_end(); | |
| 2356 } | |
| 2357 assert(_collectorState == AbortablePreclean || | |
| 2358 _collectorState == FinalMarking, | |
| 2359 "Collector state should have changed"); | |
| 2360 break; | |
| 2361 case AbortablePreclean: | |
| 2362 if (UseAdaptiveSizePolicy) { | |
| 2363 size_policy()->concurrent_phases_resume(); | |
| 2364 } | |
| 2365 abortable_preclean(); | |
| 2366 if (UseAdaptiveSizePolicy) { | |
| 2367 size_policy()->concurrent_precleaning_end(); | |
| 2368 } | |
| 2369 assert(_collectorState == FinalMarking, "Collector state should " | |
| 2370 "have changed"); | |
| 2371 break; | |
| 2372 case FinalMarking: | |
| 2373 { | |
| 2374 ReleaseForegroundGC x(this); | |
| 2375 | |
| 2376 VM_CMS_Final_Remark final_remark_op(this); | |
| 2377 VMThread::execute(&final_remark_op); | |
| 935 | 2378 } |
| 0 | 2379 assert(_foregroundGCShouldWait, "block post-condition"); |
| 2380 break; | |
| 2381 case Sweeping: | |
| 2382 if (UseAdaptiveSizePolicy) { | |
| 2383 size_policy()->concurrent_sweeping_begin(); | |
| 2384 } | |
| 2385 // final marking in checkpointRootsFinal has been completed | |
| 2386 sweep(true); | |
| 2387 assert(_collectorState == Resizing, "Collector state change " | |
| 2388 "to Resizing must be done under the free_list_lock"); | |
| 2389 _full_gcs_since_conc_gc = 0; | |
| 2390 | |
| 2391 // Stop the timers for adaptive size policy for the concurrent phases | |
| 2392 if (UseAdaptiveSizePolicy) { | |
| 2393 size_policy()->concurrent_sweeping_end(); | |
| 2394 size_policy()->concurrent_phases_end(gch->gc_cause(), | |
| 2395 gch->prev_gen(_cmsGen)->capacity(), | |
| 2396 _cmsGen->free()); | |
| 2397 } | |
| 2398 | |
| 2399 case Resizing: { | |
| 2400 // Sweeping has been completed... | |
| 2401 // At this point the background collection has completed. | |
| 2402 // Don't move the call to compute_new_size() down | |
| 2403 // into code that might be executed if the background | |
| 2404 // collection was preempted. | |
| 2405 { | |
| 2406 ReleaseForegroundGC x(this); // unblock FG collection | |
| 2407 MutexLockerEx y(Heap_lock, Mutex::_no_safepoint_check_flag); | |
| 2408 CMSTokenSync z(true); // not strictly needed. | |
| 2409 if (_collectorState == Resizing) { | |
| 2410 compute_new_size(); | |
| 10405 | 2411 save_heap_summary(); |
| 0 | 2412 _collectorState = Resetting; |
| 2413 } else { | |
| 2414 assert(_collectorState == Idling, "The state should only change" | |
| 2415 " because the foreground collector has finished the collection"); | |
| 2416 } | |
| 2417 } | |
| 2418 break; | |
| 2419 } | |
| 2420 case Resetting: | |
| 2421 // CMS heap resizing has been completed | |
| 2422 reset(true); | |
| 2423 assert(_collectorState == Idling, "Collector state should " | |
| 2424 "have changed"); | |
|
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2425 |
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2426 MetaspaceGC::set_should_concurrent_collect(false); |
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2427 |
| 0 | 2428 stats().record_cms_end(); |
| 2429 // Don't move the concurrent_phases_end() and compute_new_size() | |
| 2430 // calls to here because a preempted background collection | |
| 2431 // has it's state set to "Resetting". | |
| 2432 break; | |
| 2433 case Idling: | |
| 2434 default: | |
| 2435 ShouldNotReachHere(); | |
| 2436 break; | |
| 2437 } | |
| 2438 if (TraceCMSState) { | |
| 2439 gclog_or_tty->print_cr(" Thread " INTPTR_FORMAT " done - next CMS state %d", | |
| 2440 Thread::current(), _collectorState); | |
| 2441 } | |
| 2442 assert(_foregroundGCShouldWait, "block post-condition"); | |
| 2443 } | |
| 2444 | |
| 2445 // Should this be in gc_epilogue? | |
| 2446 collector_policy()->counters()->update_counters(); | |
| 2447 | |
| 2448 { | |
| 2449 // Clear _foregroundGCShouldWait and, in the event that the | |
| 2450 // foreground collector is waiting, notify it, before | |
| 2451 // returning. | |
| 2452 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
| 2453 _foregroundGCShouldWait = false; | |
| 2454 if (_foregroundGCIsActive) { | |
| 2455 CGC_lock->notify(); | |
| 2456 } | |
| 2457 assert(!ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 2458 "Possible deadlock"); | |
| 2459 } | |
| 2460 if (TraceCMSState) { | |
| 2461 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT | |
| 2462 " exiting collection CMS state %d", | |
| 2463 Thread::current(), _collectorState); | |
| 2464 } | |
| 2465 if (PrintGC && Verbose) { | |
| 2466 _cmsGen->print_heap_change(prev_used); | |
| 2467 } | |
| 2468 } | |
| 2469 | |
| 10405 | 2470 void CMSCollector::register_foreground_gc_start(GCCause::Cause cause) { |
| 2471 if (!_cms_start_registered) { | |
| 2472 register_gc_start(cause); | |
| 2473 } | |
| 2474 } | |
| 2475 | |
| 2476 void CMSCollector::register_gc_start(GCCause::Cause cause) { | |
| 2477 _cms_start_registered = true; | |
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2478 _gc_timer_cm->register_gc_start(); |
| 10405 | 2479 _gc_tracer_cm->report_gc_start(cause, _gc_timer_cm->gc_start()); |
| 2480 } | |
| 2481 | |
| 2482 void CMSCollector::register_gc_end() { | |
| 2483 if (_cms_start_registered) { | |
| 2484 report_heap_summary(GCWhen::AfterGC); | |
| 2485 | |
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2486 _gc_timer_cm->register_gc_end(); |
| 10405 | 2487 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); |
| 2488 _cms_start_registered = false; | |
| 2489 } | |
| 2490 } | |
| 2491 | |
| 2492 void CMSCollector::save_heap_summary() { | |
| 2493 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 2494 _last_heap_summary = gch->create_heap_summary(); | |
| 2495 _last_metaspace_summary = gch->create_metaspace_summary(); | |
| 2496 } | |
| 2497 | |
| 2498 void CMSCollector::report_heap_summary(GCWhen::Type when) { | |
| 2499 _gc_tracer_cm->report_gc_heap_summary(when, _last_heap_summary, _last_metaspace_summary); | |
| 2500 } | |
| 2501 | |
| 2502 void CMSCollector::collect_in_foreground(bool clear_all_soft_refs, GCCause::Cause cause) { | |
| 0 | 2503 assert(_foregroundGCIsActive && !_foregroundGCShouldWait, |
| 2504 "Foreground collector should be waiting, not executing"); | |
| 2505 assert(Thread::current()->is_VM_thread(), "A foreground collection" | |
| 2506 "may only be done by the VM Thread with the world stopped"); | |
| 2507 assert(ConcurrentMarkSweepThread::vm_thread_has_cms_token(), | |
| 2508 "VM thread should have CMS token"); | |
| 2509 | |
| 10405 | 2510 NOT_PRODUCT(GCTraceTime t("CMS:MS (foreground) ", PrintGCDetails && Verbose, |
| 2511 true, NULL);) | |
| 0 | 2512 if (UseAdaptiveSizePolicy) { |
| 2513 size_policy()->ms_collection_begin(); | |
| 2514 } | |
| 2515 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact); | |
| 2516 | |
| 2517 HandleMark hm; // Discard invalid handles created during verification | |
| 2518 | |
| 2519 if (VerifyBeforeGC && | |
| 2520 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
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2521 Universe::verify(); |
| 0 | 2522 } |
| 2523 | |
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2524 // Snapshot the soft reference policy to be used in this collection cycle. |
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2525 ref_processor()->setup_policy(clear_all_soft_refs); |
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2526 |
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2527 // Decide if class unloading should be done |
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2528 update_should_unload_classes(); |
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2529 |
| 0 | 2530 bool init_mark_was_synchronous = false; // until proven otherwise |
| 2531 while (_collectorState != Idling) { | |
| 2532 if (TraceCMSState) { | |
| 2533 gclog_or_tty->print_cr("Thread " INTPTR_FORMAT " in CMS state %d", | |
| 2534 Thread::current(), _collectorState); | |
| 2535 } | |
| 2536 switch (_collectorState) { | |
| 2537 case InitialMarking: | |
| 10405 | 2538 register_foreground_gc_start(cause); |
| 0 | 2539 init_mark_was_synchronous = true; // fact to be exploited in re-mark |
| 2540 checkpointRootsInitial(false); | |
| 2541 assert(_collectorState == Marking, "Collector state should have changed" | |
| 2542 " within checkpointRootsInitial()"); | |
| 2543 break; | |
| 2544 case Marking: | |
| 2545 // initial marking in checkpointRootsInitialWork has been completed | |
| 2546 if (VerifyDuringGC && | |
| 2547 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
|
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|
2548 Universe::verify("Verify before initial mark: "); |
| 0 | 2549 } |
| 2550 { | |
| 2551 bool res = markFromRoots(false); | |
| 2552 assert(res && _collectorState == FinalMarking, "Collector state should " | |
| 2553 "have changed"); | |
| 2554 break; | |
| 2555 } | |
| 2556 case FinalMarking: | |
| 2557 if (VerifyDuringGC && | |
| 2558 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
|
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|
2559 Universe::verify("Verify before re-mark: "); |
| 0 | 2560 } |
| 2561 checkpointRootsFinal(false, clear_all_soft_refs, | |
| 2562 init_mark_was_synchronous); | |
| 2563 assert(_collectorState == Sweeping, "Collector state should not " | |
| 2564 "have changed within checkpointRootsFinal()"); | |
| 2565 break; | |
| 2566 case Sweeping: | |
| 2567 // final marking in checkpointRootsFinal has been completed | |
| 2568 if (VerifyDuringGC && | |
| 2569 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
|
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|
2570 Universe::verify("Verify before sweep: "); |
| 0 | 2571 } |
| 2572 sweep(false); | |
| 2573 assert(_collectorState == Resizing, "Incorrect state"); | |
| 2574 break; | |
| 2575 case Resizing: { | |
| 2576 // Sweeping has been completed; the actual resize in this case | |
| 2577 // is done separately; nothing to be done in this state. | |
| 2578 _collectorState = Resetting; | |
| 2579 break; | |
| 2580 } | |
| 2581 case Resetting: | |
| 2582 // The heap has been resized. | |
| 2583 if (VerifyDuringGC && | |
| 2584 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
|
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|
2585 Universe::verify("Verify before reset: "); |
| 0 | 2586 } |
| 10405 | 2587 save_heap_summary(); |
| 0 | 2588 reset(false); |
| 2589 assert(_collectorState == Idling, "Collector state should " | |
| 2590 "have changed"); | |
| 2591 break; | |
| 2592 case Precleaning: | |
| 2593 case AbortablePreclean: | |
| 2594 // Elide the preclean phase | |
| 2595 _collectorState = FinalMarking; | |
| 2596 break; | |
| 2597 default: | |
| 2598 ShouldNotReachHere(); | |
| 2599 } | |
| 2600 if (TraceCMSState) { | |
| 2601 gclog_or_tty->print_cr(" Thread " INTPTR_FORMAT " done - next CMS state %d", | |
| 2602 Thread::current(), _collectorState); | |
| 2603 } | |
| 2604 } | |
| 2605 | |
| 2606 if (UseAdaptiveSizePolicy) { | |
| 2607 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 2608 size_policy()->ms_collection_end(gch->gc_cause()); | |
| 2609 } | |
| 2610 | |
| 2611 if (VerifyAfterGC && | |
| 2612 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
|
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|
2613 Universe::verify(); |
| 0 | 2614 } |
| 2615 if (TraceCMSState) { | |
| 2616 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT | |
| 2617 " exiting collection CMS state %d", | |
| 2618 Thread::current(), _collectorState); | |
| 2619 } | |
| 2620 } | |
| 2621 | |
| 2622 bool CMSCollector::waitForForegroundGC() { | |
| 2623 bool res = false; | |
| 2624 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 2625 "CMS thread should have CMS token"); | |
| 2626 // Block the foreground collector until the | |
| 2627 // background collectors decides whether to | |
| 2628 // yield. | |
| 2629 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
| 2630 _foregroundGCShouldWait = true; | |
| 2631 if (_foregroundGCIsActive) { | |
| 2632 // The background collector yields to the | |
| 2633 // foreground collector and returns a value | |
| 2634 // indicating that it has yielded. The foreground | |
| 2635 // collector can proceed. | |
| 2636 res = true; | |
| 2637 _foregroundGCShouldWait = false; | |
| 2638 ConcurrentMarkSweepThread::clear_CMS_flag( | |
| 2639 ConcurrentMarkSweepThread::CMS_cms_has_token); | |
| 2640 ConcurrentMarkSweepThread::set_CMS_flag( | |
| 2641 ConcurrentMarkSweepThread::CMS_cms_wants_token); | |
| 2642 // Get a possibly blocked foreground thread going | |
| 2643 CGC_lock->notify(); | |
| 2644 if (TraceCMSState) { | |
| 2645 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT " waiting at CMS state %d", | |
| 2646 Thread::current(), _collectorState); | |
| 2647 } | |
| 2648 while (_foregroundGCIsActive) { | |
| 2649 CGC_lock->wait(Mutex::_no_safepoint_check_flag); | |
| 2650 } | |
| 2651 ConcurrentMarkSweepThread::set_CMS_flag( | |
| 2652 ConcurrentMarkSweepThread::CMS_cms_has_token); | |
| 2653 ConcurrentMarkSweepThread::clear_CMS_flag( | |
| 2654 ConcurrentMarkSweepThread::CMS_cms_wants_token); | |
| 2655 } | |
| 2656 if (TraceCMSState) { | |
| 2657 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT " continuing at CMS state %d", | |
| 2658 Thread::current(), _collectorState); | |
| 2659 } | |
| 2660 return res; | |
| 2661 } | |
| 2662 | |
| 2663 // Because of the need to lock the free lists and other structures in | |
| 2664 // the collector, common to all the generations that the collector is | |
| 2665 // collecting, we need the gc_prologues of individual CMS generations | |
| 2666 // delegate to their collector. It may have been simpler had the | |
| 2667 // current infrastructure allowed one to call a prologue on a | |
| 2668 // collector. In the absence of that we have the generation's | |
| 2669 // prologue delegate to the collector, which delegates back | |
| 2670 // some "local" work to a worker method in the individual generations | |
| 2671 // that it's responsible for collecting, while itself doing any | |
| 2672 // work common to all generations it's responsible for. A similar | |
| 2673 // comment applies to the gc_epilogue()'s. | |
| 14309 | 2674 // The role of the variable _between_prologue_and_epilogue is to |
| 0 | 2675 // enforce the invocation protocol. |
| 2676 void CMSCollector::gc_prologue(bool full) { | |
|
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|
2677 // Call gc_prologue_work() for the CMSGen |
| 0 | 2678 // we are responsible for. |
| 2679 | |
| 2680 // The following locking discipline assumes that we are only called | |
| 2681 // when the world is stopped. | |
| 2682 assert(SafepointSynchronize::is_at_safepoint(), "world is stopped assumption"); | |
| 2683 | |
| 2684 // The CMSCollector prologue must call the gc_prologues for the | |
|
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|
2685 // "generations" that it's responsible |
| 0 | 2686 // for. |
| 2687 | |
| 2688 assert( Thread::current()->is_VM_thread() | |
| 2689 || ( CMSScavengeBeforeRemark | |
| 2690 && Thread::current()->is_ConcurrentGC_thread()), | |
| 2691 "Incorrect thread type for prologue execution"); | |
| 2692 | |
| 2693 if (_between_prologue_and_epilogue) { | |
| 2694 // We have already been invoked; this is a gc_prologue delegation | |
| 2695 // from yet another CMS generation that we are responsible for, just | |
| 2696 // ignore it since all relevant work has already been done. | |
| 2697 return; | |
| 2698 } | |
| 2699 | |
| 2700 // set a bit saying prologue has been called; cleared in epilogue | |
| 2701 _between_prologue_and_epilogue = true; | |
| 2702 // Claim locks for common data structures, then call gc_prologue_work() | |
|
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|
2703 // for each CMSGen. |
| 0 | 2704 |
| 2705 getFreelistLocks(); // gets free list locks on constituent spaces | |
| 2706 bitMapLock()->lock_without_safepoint_check(); | |
| 2707 | |
| 2708 // Should call gc_prologue_work() for all cms gens we are responsible for | |
|
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|
2709 bool duringMarking = _collectorState >= Marking |
| 0 | 2710 && _collectorState < Sweeping; |
|
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|
2711 |
|
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|
2712 // The young collections clear the modified oops state, which tells if |
|
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|
2713 // there are any modified oops in the class. The remark phase also needs |
|
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|
2714 // that information. Tell the young collection to save the union of all |
|
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|
2715 // modified klasses. |
|
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|
2716 if (duringMarking) { |
|
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|
2717 _ct->klass_rem_set()->set_accumulate_modified_oops(true); |
|
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|
2718 } |
|
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|
2719 |
|
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|
2720 bool registerClosure = duringMarking; |
|
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|
2721 |
|
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|
2722 ModUnionClosure* muc = CollectedHeap::use_parallel_gc_threads() ? |
|
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|
2723 &_modUnionClosurePar |
| 0 | 2724 : &_modUnionClosure; |
| 2725 _cmsGen->gc_prologue_work(full, registerClosure, muc); | |
| 2726 | |
| 2727 if (!full) { | |
| 2728 stats().record_gc0_begin(); | |
| 2729 } | |
| 2730 } | |
| 2731 | |
| 2732 void ConcurrentMarkSweepGeneration::gc_prologue(bool full) { | |
|
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|
2733 |
|
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|
2734 _capacity_at_prologue = capacity(); |
|
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|
2735 _used_at_prologue = used(); |
|
8617e38bb4cb
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|
2736 |
| 0 | 2737 // Delegate to CMScollector which knows how to coordinate between |
| 2738 // this and any other CMS generations that it is responsible for | |
| 2739 // collecting. | |
| 2740 collector()->gc_prologue(full); | |
| 2741 } | |
| 2742 | |
| 2743 // This is a "private" interface for use by this generation's CMSCollector. | |
| 2744 // Not to be called directly by any other entity (for instance, | |
| 2745 // GenCollectedHeap, which calls the "public" gc_prologue method above). | |
| 2746 void ConcurrentMarkSweepGeneration::gc_prologue_work(bool full, | |
| 2747 bool registerClosure, ModUnionClosure* modUnionClosure) { | |
| 2748 assert(!incremental_collection_failed(), "Shouldn't be set yet"); | |
| 2749 assert(cmsSpace()->preconsumptionDirtyCardClosure() == NULL, | |
| 2750 "Should be NULL"); | |
| 2751 if (registerClosure) { | |
| 2752 cmsSpace()->setPreconsumptionDirtyCardClosure(modUnionClosure); | |
| 2753 } | |
| 2754 cmsSpace()->gc_prologue(); | |
| 2755 // Clear stat counters | |
| 2756 NOT_PRODUCT( | |
| 2757 assert(_numObjectsPromoted == 0, "check"); | |
| 2758 assert(_numWordsPromoted == 0, "check"); | |
| 2759 if (Verbose && PrintGC) { | |
| 2760 gclog_or_tty->print("Allocated "SIZE_FORMAT" objects, " | |
| 2761 SIZE_FORMAT" bytes concurrently", | |
| 2762 _numObjectsAllocated, _numWordsAllocated*sizeof(HeapWord)); | |
| 2763 } | |
| 2764 _numObjectsAllocated = 0; | |
| 2765 _numWordsAllocated = 0; | |
| 2766 ) | |
| 2767 } | |
| 2768 | |
| 2769 void CMSCollector::gc_epilogue(bool full) { | |
| 2770 // The following locking discipline assumes that we are only called | |
| 2771 // when the world is stopped. | |
| 2772 assert(SafepointSynchronize::is_at_safepoint(), | |
| 2773 "world is stopped assumption"); | |
| 2774 | |
| 2775 // Currently the CMS epilogue (see CompactibleFreeListSpace) merely checks | |
| 2776 // if linear allocation blocks need to be appropriately marked to allow the | |
| 2777 // the blocks to be parsable. We also check here whether we need to nudge the | |
| 2778 // CMS collector thread to start a new cycle (if it's not already active). | |
| 2779 assert( Thread::current()->is_VM_thread() | |
| 2780 || ( CMSScavengeBeforeRemark | |
| 2781 && Thread::current()->is_ConcurrentGC_thread()), | |
| 2782 "Incorrect thread type for epilogue execution"); | |
| 2783 | |
| 2784 if (!_between_prologue_and_epilogue) { | |
| 2785 // We have already been invoked; this is a gc_epilogue delegation | |
| 2786 // from yet another CMS generation that we are responsible for, just | |
| 2787 // ignore it since all relevant work has already been done. | |
| 2788 return; | |
| 2789 } | |
| 2790 assert(haveFreelistLocks(), "must have freelist locks"); | |
| 2791 assert_lock_strong(bitMapLock()); | |
| 2792 | |
|
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|
2793 _ct->klass_rem_set()->set_accumulate_modified_oops(false); |
|
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|
2794 |
| 0 | 2795 _cmsGen->gc_epilogue_work(full); |
| 2796 | |
| 2797 if (_collectorState == AbortablePreclean || _collectorState == Precleaning) { | |
| 2798 // in case sampling was not already enabled, enable it | |
| 2799 _start_sampling = true; | |
| 2800 } | |
| 2801 // reset _eden_chunk_array so sampling starts afresh | |
| 2802 _eden_chunk_index = 0; | |
| 2803 | |
| 2804 size_t cms_used = _cmsGen->cmsSpace()->used(); | |
| 2805 | |
| 2806 // update performance counters - this uses a special version of | |
| 2807 // update_counters() that allows the utilization to be passed as a | |
| 2808 // parameter, avoiding multiple calls to used(). | |
| 2809 // | |
| 2810 _cmsGen->update_counters(cms_used); | |
| 2811 | |
| 2812 if (CMSIncrementalMode) { | |
| 2813 icms_update_allocation_limits(); | |
| 2814 } | |
| 2815 | |
| 2816 bitMapLock()->unlock(); | |
| 2817 releaseFreelistLocks(); | |
| 2818 | |
|
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|
2819 if (!CleanChunkPoolAsync) { |
|
48048b59a551
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|
2820 Chunk::clean_chunk_pool(); |
|
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|
2821 } |
|
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|
2822 |
|
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|
2823 set_did_compact(false); |
| 0 | 2824 _between_prologue_and_epilogue = false; // ready for next cycle |
| 2825 } | |
| 2826 | |
| 2827 void ConcurrentMarkSweepGeneration::gc_epilogue(bool full) { | |
| 2828 collector()->gc_epilogue(full); | |
| 2829 | |
| 2830 // Also reset promotion tracking in par gc thread states. | |
|
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|
2831 if (CollectedHeap::use_parallel_gc_threads()) { |
| 0 | 2832 for (uint i = 0; i < ParallelGCThreads; i++) { |
|
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|
2833 _par_gc_thread_states[i]->promo.stopTrackingPromotions(i); |
| 0 | 2834 } |
| 2835 } | |
| 2836 } | |
| 2837 | |
| 2838 void ConcurrentMarkSweepGeneration::gc_epilogue_work(bool full) { | |
| 2839 assert(!incremental_collection_failed(), "Should have been cleared"); | |
| 2840 cmsSpace()->setPreconsumptionDirtyCardClosure(NULL); | |
| 2841 cmsSpace()->gc_epilogue(); | |
| 2842 // Print stat counters | |
| 2843 NOT_PRODUCT( | |
| 2844 assert(_numObjectsAllocated == 0, "check"); | |
| 2845 assert(_numWordsAllocated == 0, "check"); | |
| 2846 if (Verbose && PrintGC) { | |
| 2847 gclog_or_tty->print("Promoted "SIZE_FORMAT" objects, " | |
| 2848 SIZE_FORMAT" bytes", | |
| 2849 _numObjectsPromoted, _numWordsPromoted*sizeof(HeapWord)); | |
| 2850 } | |
| 2851 _numObjectsPromoted = 0; | |
| 2852 _numWordsPromoted = 0; | |
| 2853 ) | |
| 2854 | |
| 2855 if (PrintGC && Verbose) { | |
| 2856 // Call down the chain in contiguous_available needs the freelistLock | |
| 2857 // so print this out before releasing the freeListLock. | |
| 2858 gclog_or_tty->print(" Contiguous available "SIZE_FORMAT" bytes ", | |
| 2859 contiguous_available()); | |
| 2860 } | |
| 2861 } | |
| 2862 | |
| 2863 #ifndef PRODUCT | |
| 2864 bool CMSCollector::have_cms_token() { | |
| 2865 Thread* thr = Thread::current(); | |
| 2866 if (thr->is_VM_thread()) { | |
| 2867 return ConcurrentMarkSweepThread::vm_thread_has_cms_token(); | |
| 2868 } else if (thr->is_ConcurrentGC_thread()) { | |
| 2869 return ConcurrentMarkSweepThread::cms_thread_has_cms_token(); | |
| 2870 } else if (thr->is_GC_task_thread()) { | |
| 2871 return ConcurrentMarkSweepThread::vm_thread_has_cms_token() && | |
| 2872 ParGCRareEvent_lock->owned_by_self(); | |
| 2873 } | |
| 2874 return false; | |
| 2875 } | |
| 2876 #endif | |
| 2877 | |
| 2878 // Check reachability of the given heap address in CMS generation, | |
| 2879 // treating all other generations as roots. | |
| 2880 bool CMSCollector::is_cms_reachable(HeapWord* addr) { | |
| 14309 | 2881 // We could "guarantee" below, rather than assert, but I'll |
| 0 | 2882 // leave these as "asserts" so that an adventurous debugger |
| 2883 // could try this in the product build provided some subset of | |
| 14309 | 2884 // the conditions were met, provided they were interested in the |
| 0 | 2885 // results and knew that the computation below wouldn't interfere |
| 2886 // with other concurrent computations mutating the structures | |
| 2887 // being read or written. | |
| 2888 assert(SafepointSynchronize::is_at_safepoint(), | |
| 2889 "Else mutations in object graph will make answer suspect"); | |
| 2890 assert(have_cms_token(), "Should hold cms token"); | |
| 2891 assert(haveFreelistLocks(), "must hold free list locks"); | |
| 2892 assert_lock_strong(bitMapLock()); | |
| 2893 | |
| 2894 // Clear the marking bit map array before starting, but, just | |
| 2895 // for kicks, first report if the given address is already marked | |
| 2896 gclog_or_tty->print_cr("Start: Address 0x%x is%s marked", addr, | |
| 2897 _markBitMap.isMarked(addr) ? "" : " not"); | |
| 2898 | |
| 2899 if (verify_after_remark()) { | |
| 2900 MutexLockerEx x(verification_mark_bm()->lock(), Mutex::_no_safepoint_check_flag); | |
| 2901 bool result = verification_mark_bm()->isMarked(addr); | |
| 2902 gclog_or_tty->print_cr("TransitiveMark: Address 0x%x %s marked", addr, | |
| 2903 result ? "IS" : "is NOT"); | |
| 2904 return result; | |
| 2905 } else { | |
| 2906 gclog_or_tty->print_cr("Could not compute result"); | |
| 2907 return false; | |
| 2908 } | |
| 2909 } | |
| 2910 | |
|
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|
2911 |
|
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|
2912 void |
|
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|
2913 CMSCollector::print_on_error(outputStream* st) { |
|
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|
2914 CMSCollector* collector = ConcurrentMarkSweepGeneration::_collector; |
|
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|
2915 if (collector != NULL) { |
|
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|
2916 CMSBitMap* bitmap = &collector->_markBitMap; |
|
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|
2917 st->print_cr("Marking Bits: (CMSBitMap*) " PTR_FORMAT, bitmap); |
|
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2918 bitmap->print_on_error(st, " Bits: "); |
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2919 |
|
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|
2920 st->cr(); |
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|
2921 |
|
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2922 CMSBitMap* mut_bitmap = &collector->_modUnionTable; |
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2923 st->print_cr("Mod Union Table: (CMSBitMap*) " PTR_FORMAT, mut_bitmap); |
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2924 mut_bitmap->print_on_error(st, " Bits: "); |
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|
2925 } |
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|
2926 } |
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2927 |
| 0 | 2928 //////////////////////////////////////////////////////// |
| 2929 // CMS Verification Support | |
| 2930 //////////////////////////////////////////////////////// | |
| 2931 // Following the remark phase, the following invariant | |
| 2932 // should hold -- each object in the CMS heap which is | |
| 2933 // marked in markBitMap() should be marked in the verification_mark_bm(). | |
| 2934 | |
| 2935 class VerifyMarkedClosure: public BitMapClosure { | |
| 2936 CMSBitMap* _marks; | |
| 2937 bool _failed; | |
| 2938 | |
| 2939 public: | |
| 2940 VerifyMarkedClosure(CMSBitMap* bm): _marks(bm), _failed(false) {} | |
| 2941 | |
|
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2942 bool do_bit(size_t offset) { |
| 0 | 2943 HeapWord* addr = _marks->offsetToHeapWord(offset); |
| 2944 if (!_marks->isMarked(addr)) { | |
|
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2945 oop(addr)->print_on(gclog_or_tty); |
| 0 | 2946 gclog_or_tty->print_cr(" ("INTPTR_FORMAT" should have been marked)", addr); |
| 2947 _failed = true; | |
| 2948 } | |
|
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2949 return true; |
| 0 | 2950 } |
| 2951 | |
| 2952 bool failed() { return _failed; } | |
| 2953 }; | |
| 2954 | |
|
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2955 bool CMSCollector::verify_after_remark(bool silent) { |
|
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2956 if (!silent) gclog_or_tty->print(" [Verifying CMS Marking... "); |
| 0 | 2957 MutexLockerEx ml(verification_mark_bm()->lock(), Mutex::_no_safepoint_check_flag); |
| 2958 static bool init = false; | |
| 2959 | |
| 2960 assert(SafepointSynchronize::is_at_safepoint(), | |
| 2961 "Else mutations in object graph will make answer suspect"); | |
| 2962 assert(have_cms_token(), | |
| 2963 "Else there may be mutual interference in use of " | |
| 2964 " verification data structures"); | |
| 2965 assert(_collectorState > Marking && _collectorState <= Sweeping, | |
| 2966 "Else marking info checked here may be obsolete"); | |
| 2967 assert(haveFreelistLocks(), "must hold free list locks"); | |
| 2968 assert_lock_strong(bitMapLock()); | |
| 2969 | |
| 2970 | |
| 2971 // Allocate marking bit map if not already allocated | |
| 2972 if (!init) { // first time | |
| 2973 if (!verification_mark_bm()->allocate(_span)) { | |
| 2974 return false; | |
| 2975 } | |
| 2976 init = true; | |
| 2977 } | |
| 2978 | |
| 2979 assert(verification_mark_stack()->isEmpty(), "Should be empty"); | |
| 2980 | |
| 2981 // Turn off refs discovery -- so we will be tracing through refs. | |
| 2982 // This is as intended, because by this time | |
| 2983 // GC must already have cleared any refs that need to be cleared, | |
| 2984 // and traced those that need to be marked; moreover, | |
| 14309 | 2985 // the marking done here is not going to interfere in any |
| 0 | 2986 // way with the marking information used by GC. |
| 2987 NoRefDiscovery no_discovery(ref_processor()); | |
| 2988 | |
| 2989 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact;) | |
| 2990 | |
| 2991 // Clear any marks from a previous round | |
| 2992 verification_mark_bm()->clear_all(); | |
| 2993 assert(verification_mark_stack()->isEmpty(), "markStack should be empty"); | |
|
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2994 verify_work_stacks_empty(); |
| 0 | 2995 |
| 2996 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 2997 gch->ensure_parsability(false); // fill TLABs, but no need to retire them | |
| 2998 // Update the saved marks which may affect the root scans. | |
| 2999 gch->save_marks(); | |
| 3000 | |
| 3001 if (CMSRemarkVerifyVariant == 1) { | |
| 3002 // In this first variant of verification, we complete | |
| 14309 | 3003 // all marking, then check if the new marks-vector is |
| 0 | 3004 // a subset of the CMS marks-vector. |
| 3005 verify_after_remark_work_1(); | |
| 3006 } else if (CMSRemarkVerifyVariant == 2) { | |
| 3007 // In this second variant of verification, we flag an error | |
| 3008 // (i.e. an object reachable in the new marks-vector not reachable | |
| 3009 // in the CMS marks-vector) immediately, also indicating the | |
| 3010 // identify of an object (A) that references the unmarked object (B) -- | |
| 3011 // presumably, a mutation to A failed to be picked up by preclean/remark? | |
| 3012 verify_after_remark_work_2(); | |
| 3013 } else { | |
| 3014 warning("Unrecognized value %d for CMSRemarkVerifyVariant", | |
| 3015 CMSRemarkVerifyVariant); | |
| 3016 } | |
|
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|
3017 if (!silent) gclog_or_tty->print(" done] "); |
| 0 | 3018 return true; |
| 3019 } | |
| 3020 | |
| 3021 void CMSCollector::verify_after_remark_work_1() { | |
| 3022 ResourceMark rm; | |
| 3023 HandleMark hm; | |
| 3024 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 3025 | |
|
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3026 // Get a clear set of claim bits for the strong roots processing to work with. |
|
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3027 ClassLoaderDataGraph::clear_claimed_marks(); |
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3028 |
| 0 | 3029 // Mark from roots one level into CMS |
|
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3030 MarkRefsIntoClosure notOlder(_span, verification_mark_bm()); |
| 0 | 3031 gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel. |
| 3032 | |
| 3033 gch->gen_process_strong_roots(_cmsGen->level(), | |
| 3034 true, // younger gens are roots | |
|
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3035 true, // activate StrongRootsScope |
| 0 | 3036 SharedHeap::ScanningOption(roots_scanning_options()), |
|
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3037 ¬Older, |
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3038 true, // walk code active on stacks |
|
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3039 NULL, |
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|
3040 NULL); // SSS: Provide correct closure |
| 0 | 3041 |
| 3042 // Now mark from the roots | |
| 3043 MarkFromRootsClosure markFromRootsClosure(this, _span, | |
|
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|
3044 verification_mark_bm(), verification_mark_stack(), |
| 0 | 3045 false /* don't yield */, true /* verifying */); |
| 3046 assert(_restart_addr == NULL, "Expected pre-condition"); | |
| 3047 verification_mark_bm()->iterate(&markFromRootsClosure); | |
| 3048 while (_restart_addr != NULL) { | |
| 3049 // Deal with stack overflow: by restarting at the indicated | |
| 3050 // address. | |
| 3051 HeapWord* ra = _restart_addr; | |
| 3052 markFromRootsClosure.reset(ra); | |
| 3053 _restart_addr = NULL; | |
| 3054 verification_mark_bm()->iterate(&markFromRootsClosure, ra, _span.end()); | |
| 3055 } | |
| 3056 assert(verification_mark_stack()->isEmpty(), "Should have been drained"); | |
| 3057 verify_work_stacks_empty(); | |
| 3058 | |
| 3059 // Marking completed -- now verify that each bit marked in | |
| 3060 // verification_mark_bm() is also marked in markBitMap(); flag all | |
| 3061 // errors by printing corresponding objects. | |
| 3062 VerifyMarkedClosure vcl(markBitMap()); | |
| 3063 verification_mark_bm()->iterate(&vcl); | |
| 3064 if (vcl.failed()) { | |
| 3065 gclog_or_tty->print("Verification failed"); | |
|
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3066 Universe::heap()->print_on(gclog_or_tty); |
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|
3067 fatal("CMS: failed marking verification after remark"); |
| 0 | 3068 } |
| 3069 } | |
| 3070 | |
|
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3071 class VerifyKlassOopsKlassClosure : public KlassClosure { |
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3072 class VerifyKlassOopsClosure : public OopClosure { |
|
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|
3073 CMSBitMap* _bitmap; |
|
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3074 public: |
|
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|
3075 VerifyKlassOopsClosure(CMSBitMap* bitmap) : _bitmap(bitmap) { } |
|
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3076 void do_oop(oop* p) { guarantee(*p == NULL || _bitmap->isMarked((HeapWord*) *p), "Should be marked"); } |
|
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3077 void do_oop(narrowOop* p) { ShouldNotReachHere(); } |
|
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|
3078 } _oop_closure; |
|
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3079 public: |
|
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|
3080 VerifyKlassOopsKlassClosure(CMSBitMap* bitmap) : _oop_closure(bitmap) {} |
|
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3081 void do_klass(Klass* k) { |
|
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|
3082 k->oops_do(&_oop_closure); |
|
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|
3083 } |
|
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|
3084 }; |
|
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|
3085 |
| 0 | 3086 void CMSCollector::verify_after_remark_work_2() { |
| 3087 ResourceMark rm; | |
| 3088 HandleMark hm; | |
| 3089 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 3090 | |
|
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3091 // Get a clear set of claim bits for the strong roots processing to work with. |
|
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|
3092 ClassLoaderDataGraph::clear_claimed_marks(); |
|
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|
3093 |
| 0 | 3094 // Mark from roots one level into CMS |
| 3095 MarkRefsIntoVerifyClosure notOlder(_span, verification_mark_bm(), | |
|
994
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|
3096 markBitMap()); |
|
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|
3097 CMKlassClosure klass_closure(¬Older); |
|
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3098 |
| 0 | 3099 gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel. |
| 3100 gch->gen_process_strong_roots(_cmsGen->level(), | |
| 3101 true, // younger gens are roots | |
|
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|
3102 true, // activate StrongRootsScope |
| 0 | 3103 SharedHeap::ScanningOption(roots_scanning_options()), |
|
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|
3104 ¬Older, |
|
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|
3105 true, // walk code active on stacks |
|
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|
3106 NULL, |
|
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|
3107 &klass_closure); |
| 0 | 3108 |
| 3109 // Now mark from the roots | |
| 3110 MarkFromRootsVerifyClosure markFromRootsClosure(this, _span, | |
| 3111 verification_mark_bm(), markBitMap(), verification_mark_stack()); | |
| 3112 assert(_restart_addr == NULL, "Expected pre-condition"); | |
| 3113 verification_mark_bm()->iterate(&markFromRootsClosure); | |
| 3114 while (_restart_addr != NULL) { | |
| 3115 // Deal with stack overflow: by restarting at the indicated | |
| 3116 // address. | |
| 3117 HeapWord* ra = _restart_addr; | |
| 3118 markFromRootsClosure.reset(ra); | |
| 3119 _restart_addr = NULL; | |
| 3120 verification_mark_bm()->iterate(&markFromRootsClosure, ra, _span.end()); | |
| 3121 } | |
| 3122 assert(verification_mark_stack()->isEmpty(), "Should have been drained"); | |
| 3123 verify_work_stacks_empty(); | |
|
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|
3124 |
|
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|
3125 VerifyKlassOopsKlassClosure verify_klass_oops(verification_mark_bm()); |
|
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|
3126 ClassLoaderDataGraph::classes_do(&verify_klass_oops); |
| 0 | 3127 |
| 3128 // Marking completed -- now verify that each bit marked in | |
| 3129 // verification_mark_bm() is also marked in markBitMap(); flag all | |
| 3130 // errors by printing corresponding objects. | |
| 3131 VerifyMarkedClosure vcl(markBitMap()); | |
| 3132 verification_mark_bm()->iterate(&vcl); | |
| 3133 assert(!vcl.failed(), "Else verification above should not have succeeded"); | |
| 3134 } | |
| 3135 | |
| 3136 void ConcurrentMarkSweepGeneration::save_marks() { | |
| 3137 // delegate to CMS space | |
| 3138 cmsSpace()->save_marks(); | |
| 3139 for (uint i = 0; i < ParallelGCThreads; i++) { | |
| 3140 _par_gc_thread_states[i]->promo.startTrackingPromotions(); | |
| 3141 } | |
| 3142 } | |
| 3143 | |
| 3144 bool ConcurrentMarkSweepGeneration::no_allocs_since_save_marks() { | |
| 3145 return cmsSpace()->no_allocs_since_save_marks(); | |
| 3146 } | |
| 3147 | |
| 3148 #define CMS_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \ | |
| 3149 \ | |
| 3150 void ConcurrentMarkSweepGeneration:: \ | |
| 3151 oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) { \ | |
| 3152 cl->set_generation(this); \ | |
| 3153 cmsSpace()->oop_since_save_marks_iterate##nv_suffix(cl); \ | |
| 3154 cl->reset_generation(); \ | |
| 3155 save_marks(); \ | |
| 3156 } | |
| 3157 | |
| 3158 ALL_SINCE_SAVE_MARKS_CLOSURES(CMS_SINCE_SAVE_MARKS_DEFN) | |
| 3159 | |
| 3160 void | |
| 3161 ConcurrentMarkSweepGeneration::younger_refs_iterate(OopsInGenClosure* cl) { | |
| 3162 cl->set_generation(this); | |
| 3163 younger_refs_in_space_iterate(_cmsSpace, cl); | |
| 3164 cl->reset_generation(); | |
| 3165 } | |
| 3166 | |
| 3167 void | |
|
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3168 ConcurrentMarkSweepGeneration::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) { |
| 0 | 3169 if (freelistLock()->owned_by_self()) { |
| 3170 Generation::oop_iterate(mr, cl); | |
| 3171 } else { | |
| 3172 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 3173 Generation::oop_iterate(mr, cl); | |
| 3174 } | |
| 3175 } | |
| 3176 | |
| 3177 void | |
|
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3178 ConcurrentMarkSweepGeneration::oop_iterate(ExtendedOopClosure* cl) { |
| 0 | 3179 if (freelistLock()->owned_by_self()) { |
| 3180 Generation::oop_iterate(cl); | |
| 3181 } else { | |
| 3182 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 3183 Generation::oop_iterate(cl); | |
| 3184 } | |
| 3185 } | |
| 3186 | |
| 3187 void | |
| 3188 ConcurrentMarkSweepGeneration::object_iterate(ObjectClosure* cl) { | |
| 3189 if (freelistLock()->owned_by_self()) { | |
| 3190 Generation::object_iterate(cl); | |
| 3191 } else { | |
| 3192 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 3193 Generation::object_iterate(cl); | |
| 3194 } | |
| 3195 } | |
| 3196 | |
| 3197 void | |
|
517
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|
3198 ConcurrentMarkSweepGeneration::safe_object_iterate(ObjectClosure* cl) { |
|
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|
3199 if (freelistLock()->owned_by_self()) { |
|
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|
3200 Generation::safe_object_iterate(cl); |
|
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|
3201 } else { |
|
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3202 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); |
|
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3203 Generation::safe_object_iterate(cl); |
|
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3204 } |
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3205 } |
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3206 |
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|
3207 void |
| 0 | 3208 ConcurrentMarkSweepGeneration::post_compact() { |
| 3209 } | |
| 3210 | |
| 3211 void | |
| 3212 ConcurrentMarkSweepGeneration::prepare_for_verify() { | |
| 3213 // Fix the linear allocation blocks to look like free blocks. | |
| 3214 | |
| 3215 // Locks are normally acquired/released in gc_prologue/gc_epilogue, but those | |
| 3216 // are not called when the heap is verified during universe initialization and | |
| 3217 // at vm shutdown. | |
| 3218 if (freelistLock()->owned_by_self()) { | |
| 3219 cmsSpace()->prepare_for_verify(); | |
| 3220 } else { | |
| 3221 MutexLockerEx fll(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 3222 cmsSpace()->prepare_for_verify(); | |
| 3223 } | |
| 3224 } | |
| 3225 | |
| 3226 void | |
| 6008 | 3227 ConcurrentMarkSweepGeneration::verify() { |
| 0 | 3228 // Locks are normally acquired/released in gc_prologue/gc_epilogue, but those |
| 3229 // are not called when the heap is verified during universe initialization and | |
| 3230 // at vm shutdown. | |
| 3231 if (freelistLock()->owned_by_self()) { | |
| 6008 | 3232 cmsSpace()->verify(); |
| 0 | 3233 } else { |
| 3234 MutexLockerEx fll(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 6008 | 3235 cmsSpace()->verify(); |
| 3236 } | |
| 3237 } | |
| 3238 | |
| 3239 void CMSCollector::verify() { | |
| 3240 _cmsGen->verify(); | |
| 0 | 3241 } |
| 3242 | |
| 3243 #ifndef PRODUCT | |
| 3244 bool CMSCollector::overflow_list_is_empty() const { | |
| 3245 assert(_num_par_pushes >= 0, "Inconsistency"); | |
| 3246 if (_overflow_list == NULL) { | |
| 3247 assert(_num_par_pushes == 0, "Inconsistency"); | |
| 3248 } | |
| 3249 return _overflow_list == NULL; | |
| 3250 } | |
| 3251 | |
| 3252 // The methods verify_work_stacks_empty() and verify_overflow_empty() | |
| 3253 // merely consolidate assertion checks that appear to occur together frequently. | |
| 3254 void CMSCollector::verify_work_stacks_empty() const { | |
| 3255 assert(_markStack.isEmpty(), "Marking stack should be empty"); | |
| 3256 assert(overflow_list_is_empty(), "Overflow list should be empty"); | |
| 3257 } | |
| 3258 | |
| 3259 void CMSCollector::verify_overflow_empty() const { | |
| 3260 assert(overflow_list_is_empty(), "Overflow list should be empty"); | |
| 3261 assert(no_preserved_marks(), "No preserved marks"); | |
| 3262 } | |
| 3263 #endif // PRODUCT | |
| 3264 | |
|
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3265 // Decide if we want to enable class unloading as part of the |
|
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3266 // ensuing concurrent GC cycle. We will collect and |
|
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3267 // unload classes if it's the case that: |
|
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|
3268 // (1) an explicit gc request has been made and the flag |
|
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|
3269 // ExplicitGCInvokesConcurrentAndUnloadsClasses is set, OR |
|
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|
3270 // (2) (a) class unloading is enabled at the command line, and |
|
6725
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3271 // (b) old gen is getting really full |
|
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3272 // NOTE: Provided there is no change in the state of the heap between |
|
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|
3273 // calls to this method, it should have idempotent results. Moreover, |
|
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|
3274 // its results should be monotonically increasing (i.e. going from 0 to 1, |
|
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|
3275 // but not 1 to 0) between successive calls between which the heap was |
|
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|
3276 // not collected. For the implementation below, it must thus rely on |
|
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|
3277 // the property that concurrent_cycles_since_last_unload() |
|
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3278 // will not decrease unless a collection cycle happened and that |
|
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3279 // _cmsGen->is_too_full() are |
|
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3280 // themselves also monotonic in that sense. See check_monotonicity() |
|
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|
3281 // below. |
|
6725
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|
3282 void CMSCollector::update_should_unload_classes() { |
|
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3283 _should_unload_classes = false; |
|
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|
3284 // Condition 1 above |
|
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|
3285 if (_full_gc_requested && ExplicitGCInvokesConcurrentAndUnloadsClasses) { |
|
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|
3286 _should_unload_classes = true; |
|
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|
3287 } else if (CMSClassUnloadingEnabled) { // Condition 2.a above |
|
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|
3288 // Disjuncts 2.b.(i,ii,iii) above |
|
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|
3289 _should_unload_classes = (concurrent_cycles_since_last_unload() >= |
|
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|
3290 CMSClassUnloadingMaxInterval) |
|
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3291 || _cmsGen->is_too_full(); |
|
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3292 } |
|
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|
3293 } |
|
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|
3294 |
|
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|
3295 bool ConcurrentMarkSweepGeneration::is_too_full() const { |
|
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|
3296 bool res = should_concurrent_collect(); |
|
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|
3297 res = res && (occupancy() > (double)CMSIsTooFullPercentage/100.0); |
|
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|
3298 return res; |
|
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|
3299 } |
|
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|
3300 |
| 0 | 3301 void CMSCollector::setup_cms_unloading_and_verification_state() { |
|
3293
1f4413413144
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|
3302 const bool should_verify = VerifyBeforeGC || VerifyAfterGC || VerifyDuringGC |
| 0 | 3303 || VerifyBeforeExit; |
|
14308
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|
3304 const int rso = SharedHeap::SO_Strings | SharedHeap::SO_AllCodeCache; |
| 0 | 3305 |
|
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3306 // We set the proper root for this CMS cycle here. |
|
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|
3307 if (should_unload_classes()) { // Should unload classes this cycle |
|
13063
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|
3308 remove_root_scanning_option(SharedHeap::SO_AllClasses); |
|
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|
3309 add_root_scanning_option(SharedHeap::SO_SystemClasses); |
| 0 | 3310 remove_root_scanning_option(rso); // Shrink the root set appropriately |
| 3311 set_verifying(should_verify); // Set verification state for this cycle | |
| 3312 return; // Nothing else needs to be done at this time | |
| 3313 } | |
| 3314 | |
| 3315 // Not unloading classes this cycle | |
|
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|
3316 assert(!should_unload_classes(), "Inconsitency!"); |
|
13063
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|
3317 remove_root_scanning_option(SharedHeap::SO_SystemClasses); |
|
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|
3318 add_root_scanning_option(SharedHeap::SO_AllClasses); |
|
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3319 |
|
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|
3320 if ((!verifying() || unloaded_classes_last_cycle()) && should_verify) { |
| 0 | 3321 // Include symbols, strings and code cache elements to prevent their resurrection. |
| 3322 add_root_scanning_option(rso); | |
| 3323 set_verifying(true); | |
| 3324 } else if (verifying() && !should_verify) { | |
| 3325 // We were verifying, but some verification flags got disabled. | |
| 3326 set_verifying(false); | |
| 3327 // Exclude symbols, strings and code cache elements from root scanning to | |
| 3328 // reduce IM and RM pauses. | |
| 3329 remove_root_scanning_option(rso); | |
| 3330 } | |
| 3331 } | |
| 3332 | |
| 3333 | |
| 3334 #ifndef PRODUCT | |
| 3335 HeapWord* CMSCollector::block_start(const void* p) const { | |
| 3336 const HeapWord* addr = (HeapWord*)p; | |
| 3337 if (_span.contains(p)) { | |
| 3338 if (_cmsGen->cmsSpace()->is_in_reserved(addr)) { | |
| 3339 return _cmsGen->cmsSpace()->block_start(p); | |
| 3340 } | |
| 3341 } | |
| 3342 return NULL; | |
| 3343 } | |
| 3344 #endif | |
| 3345 | |
| 3346 HeapWord* | |
| 3347 ConcurrentMarkSweepGeneration::expand_and_allocate(size_t word_size, | |
| 3348 bool tlab, | |
| 3349 bool parallel) { | |
|
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|
3350 CMSSynchronousYieldRequest yr; |
| 0 | 3351 assert(!tlab, "Can't deal with TLAB allocation"); |
| 3352 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 3353 expand(word_size*HeapWordSize, MinHeapDeltaBytes, | |
| 3354 CMSExpansionCause::_satisfy_allocation); | |
| 3355 if (GCExpandToAllocateDelayMillis > 0) { | |
| 3356 os::sleep(Thread::current(), GCExpandToAllocateDelayMillis, false); | |
| 3357 } | |
|
9
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|
3358 return have_lock_and_allocate(word_size, tlab); |
| 0 | 3359 } |
| 3360 | |
| 3361 // YSR: All of this generation expansion/shrinking stuff is an exact copy of | |
| 3362 // OneContigSpaceCardGeneration, which makes me wonder if we should move this | |
| 3363 // to CardGeneration and share it... | |
|
271
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|
3364 bool ConcurrentMarkSweepGeneration::expand(size_t bytes, size_t expand_bytes) { |
|
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|
3365 return CardGeneration::expand(bytes, expand_bytes); |
|
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|
3366 } |
|
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|
3367 |
| 0 | 3368 void ConcurrentMarkSweepGeneration::expand(size_t bytes, size_t expand_bytes, |
| 3369 CMSExpansionCause::Cause cause) | |
| 3370 { | |
|
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|
3371 |
|
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|
3372 bool success = expand(bytes, expand_bytes); |
|
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|
3373 |
| 0 | 3374 // remember why we expanded; this information is used |
| 3375 // by shouldConcurrentCollect() when making decisions on whether to start | |
| 3376 // a new CMS cycle. | |
| 3377 if (success) { | |
| 3378 set_expansion_cause(cause); | |
| 3379 if (PrintGCDetails && Verbose) { | |
| 3380 gclog_or_tty->print_cr("Expanded CMS gen for %s", | |
| 3381 CMSExpansionCause::to_string(cause)); | |
| 3382 } | |
| 3383 } | |
| 3384 } | |
| 3385 | |
| 3386 HeapWord* ConcurrentMarkSweepGeneration::expand_and_par_lab_allocate(CMSParGCThreadState* ps, size_t word_sz) { | |
| 3387 HeapWord* res = NULL; | |
| 3388 MutexLocker x(ParGCRareEvent_lock); | |
| 3389 while (true) { | |
| 3390 // Expansion by some other thread might make alloc OK now: | |
| 3391 res = ps->lab.alloc(word_sz); | |
| 3392 if (res != NULL) return res; | |
| 3393 // If there's not enough expansion space available, give up. | |
| 3394 if (_virtual_space.uncommitted_size() < (word_sz * HeapWordSize)) { | |
| 3395 return NULL; | |
| 3396 } | |
| 3397 // Otherwise, we try expansion. | |
| 3398 expand(word_sz*HeapWordSize, MinHeapDeltaBytes, | |
| 3399 CMSExpansionCause::_allocate_par_lab); | |
| 3400 // Now go around the loop and try alloc again; | |
| 3401 // A competing par_promote might beat us to the expansion space, | |
| 14309 | 3402 // so we may go around the loop again if promotion fails again. |
| 0 | 3403 if (GCExpandToAllocateDelayMillis > 0) { |
| 3404 os::sleep(Thread::current(), GCExpandToAllocateDelayMillis, false); | |
| 3405 } | |
| 3406 } | |
| 3407 } | |
| 3408 | |
| 3409 | |
| 3410 bool ConcurrentMarkSweepGeneration::expand_and_ensure_spooling_space( | |
| 3411 PromotionInfo* promo) { | |
| 3412 MutexLocker x(ParGCRareEvent_lock); | |
| 3413 size_t refill_size_bytes = promo->refillSize() * HeapWordSize; | |
| 3414 while (true) { | |
| 3415 // Expansion by some other thread might make alloc OK now: | |
| 3416 if (promo->ensure_spooling_space()) { | |
| 3417 assert(promo->has_spooling_space(), | |
| 3418 "Post-condition of successful ensure_spooling_space()"); | |
| 3419 return true; | |
| 3420 } | |
| 3421 // If there's not enough expansion space available, give up. | |
| 3422 if (_virtual_space.uncommitted_size() < refill_size_bytes) { | |
| 3423 return false; | |
| 3424 } | |
| 3425 // Otherwise, we try expansion. | |
| 3426 expand(refill_size_bytes, MinHeapDeltaBytes, | |
| 3427 CMSExpansionCause::_allocate_par_spooling_space); | |
| 3428 // Now go around the loop and try alloc again; | |
| 3429 // A competing allocation might beat us to the expansion space, | |
| 3430 // so we may go around the loop again if allocation fails again. | |
| 3431 if (GCExpandToAllocateDelayMillis > 0) { | |
| 3432 os::sleep(Thread::current(), GCExpandToAllocateDelayMillis, false); | |
| 3433 } | |
| 3434 } | |
| 3435 } | |
| 3436 | |
| 3437 | |
|
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3438 void ConcurrentMarkSweepGeneration::shrink_by(size_t bytes) { |
|
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|
3439 assert_locked_or_safepoint(ExpandHeap_lock); |
|
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|
3440 // Shrink committed space |
|
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|
3441 _virtual_space.shrink_by(bytes); |
|
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|
3442 // Shrink space; this also shrinks the space's BOT |
|
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|
3443 _cmsSpace->set_end((HeapWord*) _virtual_space.high()); |
|
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|
3444 size_t new_word_size = heap_word_size(_cmsSpace->capacity()); |
|
8617e38bb4cb
8008508: CMS does not correctly reduce heap size after a Full GC
jmasa
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8784
diff
changeset
|
3445 // Shrink the shared block offset array |
|
8617e38bb4cb
8008508: CMS does not correctly reduce heap size after a Full GC
jmasa
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8784
diff
changeset
|
3446 _bts->resize(new_word_size); |
|
8617e38bb4cb
8008508: CMS does not correctly reduce heap size after a Full GC
jmasa
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8784
diff
changeset
|
3447 MemRegion mr(_cmsSpace->bottom(), new_word_size); |
|
8617e38bb4cb
8008508: CMS does not correctly reduce heap size after a Full GC
jmasa
parents:
8784
diff
changeset
|
3448 // Shrink the card table |
|
8617e38bb4cb
8008508: CMS does not correctly reduce heap size after a Full GC
jmasa
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8784
diff
changeset
|
3449 Universe::heap()->barrier_set()->resize_covered_region(mr); |
|
8617e38bb4cb
8008508: CMS does not correctly reduce heap size after a Full GC
jmasa
parents:
8784
diff
changeset
|
3450 |
|
8617e38bb4cb
8008508: CMS does not correctly reduce heap size after a Full GC
jmasa
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8784
diff
changeset
|
3451 if (Verbose && PrintGC) { |
|
8617e38bb4cb
8008508: CMS does not correctly reduce heap size after a Full GC
jmasa
parents:
8784
diff
changeset
|
3452 size_t new_mem_size = _virtual_space.committed_size(); |
|
8617e38bb4cb
8008508: CMS does not correctly reduce heap size after a Full GC
jmasa
parents:
8784
diff
changeset
|
3453 size_t old_mem_size = new_mem_size + bytes; |
|
8617e38bb4cb
8008508: CMS does not correctly reduce heap size after a Full GC
jmasa
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8784
diff
changeset
|
3454 gclog_or_tty->print_cr("Shrinking %s from " SIZE_FORMAT "K to " SIZE_FORMAT "K", |
|
8617e38bb4cb
8008508: CMS does not correctly reduce heap size after a Full GC
jmasa
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8784
diff
changeset
|
3455 name(), old_mem_size/K, new_mem_size/K); |
|
8617e38bb4cb
8008508: CMS does not correctly reduce heap size after a Full GC
jmasa
parents:
8784
diff
changeset
|
3456 } |
|
8617e38bb4cb
8008508: CMS does not correctly reduce heap size after a Full GC
jmasa
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8784
diff
changeset
|
3457 } |
| 0 | 3458 |
| 3459 void ConcurrentMarkSweepGeneration::shrink(size_t bytes) { | |
| 3460 assert_locked_or_safepoint(Heap_lock); | |
| 3461 size_t size = ReservedSpace::page_align_size_down(bytes); | |
|
12112
1bb10d3170fa
8022817: CMS should not shrink if compaction was not done
jmasa
parents:
12088
diff
changeset
|
3462 // Only shrink if a compaction was done so that all the free space |
|
1bb10d3170fa
8022817: CMS should not shrink if compaction was not done
jmasa
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12088
diff
changeset
|
3463 // in the generation is in a contiguous block at the end. |
|
1bb10d3170fa
8022817: CMS should not shrink if compaction was not done
jmasa
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12088
diff
changeset
|
3464 if (size > 0 && did_compact()) { |
| 0 | 3465 shrink_by(size); |
| 3466 } | |
| 3467 } | |
| 3468 | |
| 3469 bool ConcurrentMarkSweepGeneration::grow_by(size_t bytes) { | |
| 3470 assert_locked_or_safepoint(Heap_lock); | |
| 3471 bool result = _virtual_space.expand_by(bytes); | |
| 3472 if (result) { | |
| 3473 size_t new_word_size = | |
| 3474 heap_word_size(_virtual_space.committed_size()); | |
| 3475 MemRegion mr(_cmsSpace->bottom(), new_word_size); | |
| 3476 _bts->resize(new_word_size); // resize the block offset shared array | |
| 3477 Universe::heap()->barrier_set()->resize_covered_region(mr); | |
| 3478 // Hmmmm... why doesn't CFLS::set_end verify locking? | |
| 3479 // This is quite ugly; FIX ME XXX | |
|
1145
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
3480 _cmsSpace->assert_locked(freelistLock()); |
| 0 | 3481 _cmsSpace->set_end((HeapWord*)_virtual_space.high()); |
| 3482 | |
| 3483 // update the space and generation capacity counters | |
| 3484 if (UsePerfData) { | |
| 3485 _space_counters->update_capacity(); | |
| 3486 _gen_counters->update_all(); | |
| 3487 } | |
| 3488 | |
| 3489 if (Verbose && PrintGC) { | |
| 3490 size_t new_mem_size = _virtual_space.committed_size(); | |
| 3491 size_t old_mem_size = new_mem_size - bytes; | |
|
7623
203f64878aab
7102489: RFE: cleanup jlong typedef on __APPLE__and _LLP64 systems.
hseigel
parents:
6885
diff
changeset
|
3492 gclog_or_tty->print_cr("Expanding %s from " SIZE_FORMAT "K by " SIZE_FORMAT "K to " SIZE_FORMAT "K", |
| 0 | 3493 name(), old_mem_size/K, bytes/K, new_mem_size/K); |
| 3494 } | |
| 3495 } | |
| 3496 return result; | |
| 3497 } | |
| 3498 | |
| 3499 bool ConcurrentMarkSweepGeneration::grow_to_reserved() { | |
| 3500 assert_locked_or_safepoint(Heap_lock); | |
| 3501 bool success = true; | |
| 3502 const size_t remaining_bytes = _virtual_space.uncommitted_size(); | |
| 3503 if (remaining_bytes > 0) { | |
| 3504 success = grow_by(remaining_bytes); | |
| 3505 DEBUG_ONLY(if (!success) warning("grow to reserved failed");) | |
| 3506 } | |
| 3507 return success; | |
| 3508 } | |
| 3509 | |
|
9072
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8008508: CMS does not correctly reduce heap size after a Full GC
jmasa
parents:
8784
diff
changeset
|
3510 void ConcurrentMarkSweepGeneration::shrink_free_list_by(size_t bytes) { |
| 0 | 3511 assert_locked_or_safepoint(Heap_lock); |
| 3512 assert_lock_strong(freelistLock()); | |
|
10180
ebded0261dfc
8012111: Remove warning about CMS generation shrinking.
jmasa
parents:
9152
diff
changeset
|
3513 if (PrintGCDetails && Verbose) { |
|
ebded0261dfc
8012111: Remove warning about CMS generation shrinking.
jmasa
parents:
9152
diff
changeset
|
3514 warning("Shrinking of CMS not yet implemented"); |
|
ebded0261dfc
8012111: Remove warning about CMS generation shrinking.
jmasa
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9152
diff
changeset
|
3515 } |
| 0 | 3516 return; |
| 3517 } | |
| 3518 | |
| 3519 | |
| 3520 // Simple ctor/dtor wrapper for accounting & timer chores around concurrent | |
| 3521 // phases. | |
| 3522 class CMSPhaseAccounting: public StackObj { | |
| 3523 public: | |
| 3524 CMSPhaseAccounting(CMSCollector *collector, | |
| 3525 const char *phase, | |
| 3526 bool print_cr = true); | |
| 3527 ~CMSPhaseAccounting(); | |
| 3528 | |
| 3529 private: | |
| 3530 CMSCollector *_collector; | |
| 3531 const char *_phase; | |
| 3532 elapsedTimer _wallclock; | |
| 3533 bool _print_cr; | |
| 3534 | |
| 3535 public: | |
| 3536 // Not MT-safe; so do not pass around these StackObj's | |
| 3537 // where they may be accessed by other threads. | |
| 3538 jlong wallclock_millis() { | |
| 3539 assert(_wallclock.is_active(), "Wall clock should not stop"); | |
| 3540 _wallclock.stop(); // to record time | |
| 3541 jlong ret = _wallclock.milliseconds(); | |
| 3542 _wallclock.start(); // restart | |
| 3543 return ret; | |
| 3544 } | |
| 3545 }; | |
| 3546 | |
| 3547 CMSPhaseAccounting::CMSPhaseAccounting(CMSCollector *collector, | |
| 3548 const char *phase, | |
| 3549 bool print_cr) : | |
| 3550 _collector(collector), _phase(phase), _print_cr(print_cr) { | |
| 3551 | |
| 3552 if (PrintCMSStatistics != 0) { | |
| 3553 _collector->resetYields(); | |
| 3554 } | |
|
8740
62609ffa2fc6
8008684: CMS: concurrent phase start markers should always be printed
tschatzl
parents:
8736
diff
changeset
|
3555 if (PrintGCDetails) { |
| 0 | 3556 gclog_or_tty->date_stamp(PrintGCDateStamps); |
|
8740
62609ffa2fc6
8008684: CMS: concurrent phase start markers should always be printed
tschatzl
parents:
8736
diff
changeset
|
3557 gclog_or_tty->stamp(PrintGCTimeStamps); |
|
62609ffa2fc6
8008684: CMS: concurrent phase start markers should always be printed
tschatzl
parents:
8736
diff
changeset
|
3558 gclog_or_tty->print_cr("[%s-concurrent-%s-start]", |
| 0 | 3559 _collector->cmsGen()->short_name(), _phase); |
| 3560 } | |
| 3561 _collector->resetTimer(); | |
| 3562 _wallclock.start(); | |
| 3563 _collector->startTimer(); | |
| 3564 } | |
| 3565 | |
| 3566 CMSPhaseAccounting::~CMSPhaseAccounting() { | |
| 3567 assert(_wallclock.is_active(), "Wall clock should not have stopped"); | |
| 3568 _collector->stopTimer(); | |
| 3569 _wallclock.stop(); | |
| 3570 if (PrintGCDetails) { | |
| 3571 gclog_or_tty->date_stamp(PrintGCDateStamps); | |
|
6752
9646b7ff4d14
7198130: G1: PrintReferenceGC output comes out of order
brutisso
parents:
6725
diff
changeset
|
3572 gclog_or_tty->stamp(PrintGCTimeStamps); |
| 0 | 3573 gclog_or_tty->print("[%s-concurrent-%s: %3.3f/%3.3f secs]", |
| 3574 _collector->cmsGen()->short_name(), | |
| 3575 _phase, _collector->timerValue(), _wallclock.seconds()); | |
| 3576 if (_print_cr) { | |
| 3577 gclog_or_tty->print_cr(""); | |
| 3578 } | |
| 3579 if (PrintCMSStatistics != 0) { | |
| 3580 gclog_or_tty->print_cr(" (CMS-concurrent-%s yielded %d times)", _phase, | |
| 3581 _collector->yields()); | |
| 3582 } | |
| 3583 } | |
| 3584 } | |
| 3585 | |
| 3586 // CMS work | |
| 3587 | |
| 11975 | 3588 // The common parts of CMSParInitialMarkTask and CMSParRemarkTask. |
| 3589 class CMSParMarkTask : public AbstractGangTask { | |
| 3590 protected: | |
| 3591 CMSCollector* _collector; | |
| 3592 int _n_workers; | |
| 3593 CMSParMarkTask(const char* name, CMSCollector* collector, int n_workers) : | |
| 3594 AbstractGangTask(name), | |
| 3595 _collector(collector), | |
| 3596 _n_workers(n_workers) {} | |
| 3597 // Work method in support of parallel rescan ... of young gen spaces | |
| 3598 void do_young_space_rescan(uint worker_id, OopsInGenClosure* cl, | |
| 3599 ContiguousSpace* space, | |
| 3600 HeapWord** chunk_array, size_t chunk_top); | |
| 3601 void work_on_young_gen_roots(uint worker_id, OopsInGenClosure* cl); | |
| 3602 }; | |
| 3603 | |
| 3604 // Parallel initial mark task | |
| 3605 class CMSParInitialMarkTask: public CMSParMarkTask { | |
| 3606 public: | |
| 3607 CMSParInitialMarkTask(CMSCollector* collector, int n_workers) : | |
| 3608 CMSParMarkTask("Scan roots and young gen for initial mark in parallel", | |
| 3609 collector, n_workers) {} | |
| 3610 void work(uint worker_id); | |
| 3611 }; | |
| 3612 | |
| 0 | 3613 // Checkpoint the roots into this generation from outside |
| 3614 // this generation. [Note this initial checkpoint need only | |
| 3615 // be approximate -- we'll do a catch up phase subsequently.] | |
| 3616 void CMSCollector::checkpointRootsInitial(bool asynch) { | |
| 3617 assert(_collectorState == InitialMarking, "Wrong collector state"); | |
| 3618 check_correct_thread_executing(); | |
|
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
parents:
3293
diff
changeset
|
3619 TraceCMSMemoryManagerStats tms(_collectorState,GenCollectedHeap::heap()->gc_cause()); |
|
2125
7246a374a9f2
6458402: 3 jvmti tests fail with CMS and +ExplicitGCInvokesConcurrent
kamg
parents:
1994
diff
changeset
|
3620 |
| 10405 | 3621 save_heap_summary(); |
| 3622 report_heap_summary(GCWhen::BeforeGC); | |
| 3623 | |
| 0 | 3624 ReferenceProcessor* rp = ref_processor(); |
| 3625 SpecializationStats::clear(); | |
| 3626 assert(_restart_addr == NULL, "Control point invariant"); | |
| 3627 if (asynch) { | |
| 3628 // acquire locks for subsequent manipulations | |
| 3629 MutexLockerEx x(bitMapLock(), | |
| 3630 Mutex::_no_safepoint_check_flag); | |
| 3631 checkpointRootsInitialWork(asynch); | |
|
3979
4dfb2df418f2
6484982: G1: process references during evacuation pauses
johnc
parents:
3827
diff
changeset
|
3632 // enable ("weak") refs discovery |
|
4dfb2df418f2
6484982: G1: process references during evacuation pauses
johnc
parents:
3827
diff
changeset
|
3633 rp->enable_discovery(true /*verify_disabled*/, true /*check_no_refs*/); |
| 0 | 3634 _collectorState = Marking; |
| 3635 } else { | |
| 3636 // (Weak) Refs discovery: this is controlled from genCollectedHeap::do_collection | |
| 3637 // which recognizes if we are a CMS generation, and doesn't try to turn on | |
| 3638 // discovery; verify that they aren't meddling. | |
| 3639 assert(!rp->discovery_is_atomic(), | |
| 3640 "incorrect setting of discovery predicate"); | |
| 3641 assert(!rp->discovery_enabled(), "genCollectedHeap shouldn't control " | |
| 3642 "ref discovery for this generation kind"); | |
| 3643 // already have locks | |
| 3644 checkpointRootsInitialWork(asynch); | |
|
3979
4dfb2df418f2
6484982: G1: process references during evacuation pauses
johnc
parents:
3827
diff
changeset
|
3645 // now enable ("weak") refs discovery |
|
4dfb2df418f2
6484982: G1: process references during evacuation pauses
johnc
parents:
3827
diff
changeset
|
3646 rp->enable_discovery(true /*verify_disabled*/, false /*verify_no_refs*/); |
| 0 | 3647 _collectorState = Marking; |
| 3648 } | |
| 3649 SpecializationStats::print(); | |
| 3650 } | |
| 3651 | |
| 3652 void CMSCollector::checkpointRootsInitialWork(bool asynch) { | |
| 3653 assert(SafepointSynchronize::is_at_safepoint(), "world should be stopped"); | |
| 3654 assert(_collectorState == InitialMarking, "just checking"); | |
| 3655 | |
| 3656 // If there has not been a GC[n-1] since last GC[n] cycle completed, | |
| 3657 // precede our marking with a collection of all | |
| 3658 // younger generations to keep floating garbage to a minimum. | |
| 3659 // XXX: we won't do this for now -- it's an optimization to be done later. | |
| 3660 | |
| 3661 // already have locks | |
| 3662 assert_lock_strong(bitMapLock()); | |
| 3663 assert(_markBitMap.isAllClear(), "was reset at end of previous cycle"); | |
| 3664 | |
| 3665 // Setup the verification and class unloading state for this | |
| 3666 // CMS collection cycle. | |
| 3667 setup_cms_unloading_and_verification_state(); | |
| 3668 | |
| 10405 | 3669 NOT_PRODUCT(GCTraceTime t("\ncheckpointRootsInitialWork", |
| 3670 PrintGCDetails && Verbose, true, _gc_timer_cm);) | |
| 0 | 3671 if (UseAdaptiveSizePolicy) { |
| 3672 size_policy()->checkpoint_roots_initial_begin(); | |
| 3673 } | |
| 3674 | |
| 3675 // Reset all the PLAB chunk arrays if necessary. | |
| 3676 if (_survivor_plab_array != NULL && !CMSPLABRecordAlways) { | |
| 3677 reset_survivor_plab_arrays(); | |
| 3678 } | |
| 3679 | |
| 3680 ResourceMark rm; | |
| 3681 HandleMark hm; | |
| 3682 | |
| 3683 FalseClosure falseClosure; | |
| 3684 // In the case of a synchronous collection, we will elide the | |
| 3685 // 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
|
3686 // in this step. |
|
753cf9794df9
6885169: merge of 4957990 and 6863023 causes conflict on do_nmethods
jrose
parents:
993
diff
changeset
|
3687 // 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
|
3688 // 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
|
3689 MarkRefsIntoClosure notOlder(_span, &_markBitMap); |
| 0 | 3690 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
| 3691 | |
| 3692 verify_work_stacks_empty(); | |
| 3693 verify_overflow_empty(); | |
| 3694 | |
| 3695 gch->ensure_parsability(false); // fill TLABs, but no need to retire them | |
| 3696 // Update the saved marks which may affect the root scans. | |
| 3697 gch->save_marks(); | |
| 3698 | |
| 3699 // weak reference processing has not started yet. | |
| 3700 ref_processor()->set_enqueuing_is_done(false); | |
| 3701 | |
|
6725
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
3702 // Need to remember all newly created CLDs, |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
3703 // so that we can guarantee that the remark finds them. |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
3704 ClassLoaderDataGraph::remember_new_clds(true); |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
3705 |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
3706 // 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
parents:
6197
diff
changeset
|
3707 // the klasses. The claimed marks need to be cleared before marking starts. |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
3708 ClassLoaderDataGraph::clear_claimed_marks(); |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
3709 |
|
11973
7b06ae405d7b
6990419: CMS Remaining work for 6572569: consistently skewed work distribution in (long) re-mark pauses
jmasa
parents:
11096
diff
changeset
|
3710 if (CMSPrintEdenSurvivorChunks) { |
|
7b06ae405d7b
6990419: CMS Remaining work for 6572569: consistently skewed work distribution in (long) re-mark pauses
jmasa
parents:
11096
diff
changeset
|
3711 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
|
3712 } |
|
7b06ae405d7b
6990419: CMS Remaining work for 6572569: consistently skewed work distribution in (long) re-mark pauses
jmasa
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11096
diff
changeset
|
3713 |
| 0 | 3714 { |
| 3715 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact;) | |
| 11975 | 3716 if (CMSParallelInitialMarkEnabled && CollectedHeap::use_parallel_gc_threads()) { |
| 3717 // The parallel version. | |
| 3718 FlexibleWorkGang* workers = gch->workers(); | |
| 3719 assert(workers != NULL, "Need parallel worker threads."); | |
| 3720 int n_workers = workers->active_workers(); | |
| 3721 CMSParInitialMarkTask tsk(this, n_workers); | |
| 3722 gch->set_par_threads(n_workers); | |
| 3723 initialize_sequential_subtasks_for_young_gen_rescan(n_workers); | |
| 3724 if (n_workers > 1) { | |
| 3725 GenCollectedHeap::StrongRootsScope srs(gch); | |
| 3726 workers->run_task(&tsk); | |
| 3727 } else { | |
| 3728 GenCollectedHeap::StrongRootsScope srs(gch); | |
| 3729 tsk.work(0); | |
| 3730 } | |
| 3731 gch->set_par_threads(0); | |
| 3732 } else { | |
| 3733 // The serial version. | |
| 3734 CMKlassClosure klass_closure(¬Older); | |
| 3735 gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel. | |
| 3736 gch->gen_process_strong_roots(_cmsGen->level(), | |
| 3737 true, // younger gens are roots | |
| 3738 true, // activate StrongRootsScope | |
| 3739 SharedHeap::ScanningOption(roots_scanning_options()), | |
| 3740 ¬Older, | |
|
14308
870aedf4ba4f
8032379: Remove the is_scavenging flag to process_strong_roots
mgerdin
parents:
13400
diff
changeset
|
3741 true, // walk all of code cache if (so & SO_AllCodeCache) |
| 11975 | 3742 NULL, |
| 3743 &klass_closure); | |
| 3744 } | |
| 0 | 3745 } |
| 3746 | |
| 3747 // Clear mod-union table; it will be dirtied in the prologue of | |
| 3748 // CMS generation per each younger generation collection. | |
| 3749 | |
| 3750 assert(_modUnionTable.isAllClear(), | |
| 3751 "Was cleared in most recent final checkpoint phase" | |
| 3752 " or no bits are set in the gc_prologue before the start of the next " | |
| 3753 "subsequent marking phase."); | |
| 3754 | |
|
6725
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
3755 assert(_ct->klass_rem_set()->mod_union_is_clear(), "Must be"); |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
3756 |
| 0 | 3757 // Save the end of the used_region of the constituent generations |
| 3758 // to be used to limit the extent of sweep in each generation. | |
| 3759 save_sweep_limits(); | |
| 3760 if (UseAdaptiveSizePolicy) { | |
| 3761 size_policy()->checkpoint_roots_initial_end(gch->gc_cause()); | |
| 3762 } | |
| 3763 verify_overflow_empty(); | |
| 3764 } | |
| 3765 | |
| 3766 bool CMSCollector::markFromRoots(bool asynch) { | |
| 3767 // we might be tempted to assert that: | |
| 3768 // assert(asynch == !SafepointSynchronize::is_at_safepoint(), | |
| 3769 // "inconsistent argument?"); | |
| 3770 // However that wouldn't be right, because it's possible that | |
| 3771 // a safepoint is indeed in progress as a younger generation | |
| 3772 // stop-the-world GC happens even as we mark in this generation. | |
| 3773 assert(_collectorState == Marking, "inconsistent state?"); | |
| 3774 check_correct_thread_executing(); | |
| 3775 verify_overflow_empty(); | |
| 3776 | |
| 3777 bool res; | |
| 3778 if (asynch) { | |
| 3779 | |
| 3780 // Start the timers for adaptive size policy for the concurrent phases | |
| 3781 // Do it here so that the foreground MS can use the concurrent | |
| 3782 // timer since a foreground MS might has the sweep done concurrently | |
| 3783 // or STW. | |
| 3784 if (UseAdaptiveSizePolicy) { | |
| 3785 size_policy()->concurrent_marking_begin(); | |
| 3786 } | |
| 3787 | |
| 3788 // Weak ref discovery note: We may be discovering weak | |
| 3789 // refs in this generation concurrent (but interleaved) with | |
| 3790 // weak ref discovery by a younger generation collector. | |
| 3791 | |
| 3792 CMSTokenSyncWithLocks ts(true, bitMapLock()); | |
| 3793 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
| 3794 CMSPhaseAccounting pa(this, "mark", !PrintGCDetails); | |
| 3795 res = markFromRootsWork(asynch); | |
| 3796 if (res) { | |
| 3797 _collectorState = Precleaning; | |
| 3798 } else { // We failed and a foreground collection wants to take over | |
| 3799 assert(_foregroundGCIsActive, "internal state inconsistency"); | |
| 3800 assert(_restart_addr == NULL, "foreground will restart from scratch"); | |
| 3801 if (PrintGCDetails) { | |
| 3802 gclog_or_tty->print_cr("bailing out to foreground collection"); | |
| 3803 } | |
| 3804 } | |
| 3805 if (UseAdaptiveSizePolicy) { | |
| 3806 size_policy()->concurrent_marking_end(); | |
| 3807 } | |
| 3808 } else { | |
| 3809 assert(SafepointSynchronize::is_at_safepoint(), | |
| 3810 "inconsistent with asynch == false"); | |
| 3811 if (UseAdaptiveSizePolicy) { | |
| 3812 size_policy()->ms_collection_marking_begin(); | |
| 3813 } | |
| 3814 // already have locks | |
| 3815 res = markFromRootsWork(asynch); | |
| 3816 _collectorState = FinalMarking; | |
| 3817 if (UseAdaptiveSizePolicy) { | |
| 3818 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 3819 size_policy()->ms_collection_marking_end(gch->gc_cause()); | |
| 3820 } | |
| 3821 } | |
| 3822 verify_overflow_empty(); | |
| 3823 return res; | |
| 3824 } | |
| 3825 | |
| 3826 bool CMSCollector::markFromRootsWork(bool asynch) { | |
| 3827 // iterate over marked bits in bit map, doing a full scan and mark | |
| 3828 // from these roots using the following algorithm: | |
| 3829 // . if oop is to the right of the current scan pointer, | |
| 3830 // mark corresponding bit (we'll process it later) | |
| 3831 // . else (oop is to left of current scan pointer) | |
| 3832 // push oop on marking stack | |
| 3833 // . drain the marking stack | |
| 3834 | |
| 3835 // Note that when we do a marking step we need to hold the | |
| 3836 // bit map lock -- recall that direct allocation (by mutators) | |
| 3837 // and promotion (by younger generation collectors) is also | |
| 3838 // marking the bit map. [the so-called allocate live policy.] | |
| 3839 // Because the implementation of bit map marking is not | |
| 3840 // robust wrt simultaneous marking of bits in the same word, | |
| 3841 // we need to make sure that there is no such interference | |
| 3842 // between concurrent such updates. | |
| 3843 | |
| 3844 // already have locks | |
| 3845 assert_lock_strong(bitMapLock()); | |
| 3846 | |
| 3847 verify_work_stacks_empty(); | |
| 3848 verify_overflow_empty(); | |
| 3849 bool result = false; | |
| 1284 | 3850 if (CMSConcurrentMTEnabled && ConcGCThreads > 0) { |
| 0 | 3851 result = do_marking_mt(asynch); |
| 3852 } else { | |
| 3853 result = do_marking_st(asynch); | |
| 3854 } | |
| 3855 return result; | |
| 3856 } | |
| 3857 | |
| 3858 // Forward decl | |
| 3859 class CMSConcMarkingTask; | |
| 3860 | |
| 3861 class CMSConcMarkingTerminator: public ParallelTaskTerminator { | |
| 3862 CMSCollector* _collector; | |
| 3863 CMSConcMarkingTask* _task; | |
|
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3864 public: |
| 0 | 3865 virtual void yield(); |
|
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3866 |
| 0 | 3867 // "n_threads" is the number of threads to be terminated. |
| 3868 // "queue_set" is a set of work queues of other threads. | |
| 3869 // "collector" is the CMS collector associated with this task terminator. | |
| 3870 // "yield" indicates whether we need the gang as a whole to yield. | |
|
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3871 CMSConcMarkingTerminator(int n_threads, TaskQueueSetSuper* queue_set, CMSCollector* collector) : |
| 0 | 3872 ParallelTaskTerminator(n_threads, queue_set), |
|
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3873 _collector(collector) { } |
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3874 |
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3875 void set_task(CMSConcMarkingTask* task) { |
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3876 _task = task; |
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3877 } |
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3878 }; |
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3879 |
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3880 class CMSConcMarkingTerminatorTerminator: public TerminatorTerminator { |
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3881 CMSConcMarkingTask* _task; |
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3882 public: |
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3883 bool should_exit_termination(); |
| 0 | 3884 void set_task(CMSConcMarkingTask* task) { |
| 3885 _task = task; | |
| 3886 } | |
| 3887 }; | |
| 3888 | |
| 3889 // MT Concurrent Marking Task | |
| 3890 class CMSConcMarkingTask: public YieldingFlexibleGangTask { | |
| 3891 CMSCollector* _collector; | |
| 3892 int _n_workers; // requested/desired # workers | |
| 3893 bool _asynch; | |
| 3894 bool _result; | |
| 3895 CompactibleFreeListSpace* _cms_space; | |
|
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3896 char _pad_front[64]; // padding to ... |
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3897 HeapWord* _global_finger; // ... avoid sharing cache line |
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3898 char _pad_back[64]; |
|
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3899 HeapWord* _restart_addr; |
| 0 | 3900 |
| 3901 // Exposed here for yielding support | |
| 3902 Mutex* const _bit_map_lock; | |
| 3903 | |
| 3904 // The per thread work queues, available here for stealing | |
| 3905 OopTaskQueueSet* _task_queues; | |
|
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3906 |
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3907 // Termination (and yielding) support |
| 0 | 3908 CMSConcMarkingTerminator _term; |
|
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3909 CMSConcMarkingTerminatorTerminator _term_term; |
| 0 | 3910 |
| 3911 public: | |
| 3912 CMSConcMarkingTask(CMSCollector* collector, | |
| 3913 CompactibleFreeListSpace* cms_space, | |
|
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3914 bool asynch, |
| 0 | 3915 YieldingFlexibleWorkGang* workers, |
| 3916 OopTaskQueueSet* task_queues): | |
| 3917 YieldingFlexibleGangTask("Concurrent marking done multi-threaded"), | |
| 3918 _collector(collector), | |
| 3919 _cms_space(cms_space), | |
|
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3920 _asynch(asynch), _n_workers(0), _result(true), |
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3921 _task_queues(task_queues), |
|
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3922 _term(_n_workers, task_queues, _collector), |
| 0 | 3923 _bit_map_lock(collector->bitMapLock()) |
| 3924 { | |
|
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3925 _requested_size = _n_workers; |
| 0 | 3926 _term.set_task(this); |
|
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3927 _term_term.set_task(this); |
|
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3928 _restart_addr = _global_finger = _cms_space->bottom(); |
| 0 | 3929 } |
| 3930 | |
| 3931 | |
| 3932 OopTaskQueueSet* task_queues() { return _task_queues; } | |
| 3933 | |
| 3934 OopTaskQueue* work_queue(int i) { return task_queues()->queue(i); } | |
| 3935 | |
| 3936 HeapWord** global_finger_addr() { return &_global_finger; } | |
| 3937 | |
| 3938 CMSConcMarkingTerminator* terminator() { return &_term; } | |
| 3939 | |
|
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3940 virtual void set_for_termination(int active_workers) { |
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3941 terminator()->reset_for_reuse(active_workers); |
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3942 } |
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3943 |
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3944 void work(uint worker_id); |
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3945 bool should_yield() { |
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3946 return ConcurrentMarkSweepThread::should_yield() |
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3947 && !_collector->foregroundGCIsActive() |
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3948 && _asynch; |
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3949 } |
| 0 | 3950 |
| 3951 virtual void coordinator_yield(); // stuff done by coordinator | |
| 3952 bool result() { return _result; } | |
| 3953 | |
| 3954 void reset(HeapWord* ra) { | |
|
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3955 assert(_global_finger >= _cms_space->end(), "Postcondition of ::work(i)"); |
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3956 _restart_addr = _global_finger = ra; |
| 0 | 3957 _term.reset_for_reuse(); |
| 3958 } | |
| 3959 | |
| 3960 static bool get_work_from_overflow_stack(CMSMarkStack* ovflw_stk, | |
| 3961 OopTaskQueue* work_q); | |
| 3962 | |
| 3963 private: | |
| 3964 void do_scan_and_mark(int i, CompactibleFreeListSpace* sp); | |
| 3965 void do_work_steal(int i); | |
| 3966 void bump_global_finger(HeapWord* f); | |
| 3967 }; | |
| 3968 | |
|
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3969 bool CMSConcMarkingTerminatorTerminator::should_exit_termination() { |
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3970 assert(_task != NULL, "Error"); |
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3971 return _task->yielding(); |
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3972 // Note that we do not need the disjunct || _task->should_yield() above |
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3973 // because we want terminating threads to yield only if the task |
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3974 // is already in the midst of yielding, which happens only after at least one |
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3975 // thread has yielded. |
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3976 } |
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3977 |
| 0 | 3978 void CMSConcMarkingTerminator::yield() { |
|
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3979 if (_task->should_yield()) { |
| 0 | 3980 _task->yield(); |
| 3981 } else { | |
| 3982 ParallelTaskTerminator::yield(); | |
| 3983 } | |
| 3984 } | |
| 3985 | |
| 3986 //////////////////////////////////////////////////////////////// | |
| 3987 // Concurrent Marking Algorithm Sketch | |
| 3988 //////////////////////////////////////////////////////////////// | |
| 3989 // Until all tasks exhausted (both spaces): | |
| 3990 // -- claim next available chunk | |
| 3991 // -- bump global finger via CAS | |
| 3992 // -- find first object that starts in this chunk | |
| 3993 // and start scanning bitmap from that position | |
| 3994 // -- scan marked objects for oops | |
| 3995 // -- CAS-mark target, and if successful: | |
| 3996 // . if target oop is above global finger (volatile read) | |
| 3997 // nothing to do | |
| 3998 // . if target oop is in chunk and above local finger | |
| 3999 // then nothing to do | |
| 4000 // . else push on work-queue | |
| 4001 // -- Deal with possible overflow issues: | |
| 4002 // . local work-queue overflow causes stuff to be pushed on | |
| 4003 // global (common) overflow queue | |
| 4004 // . always first empty local work queue | |
| 4005 // . then get a batch of oops from global work queue if any | |
| 4006 // . then do work stealing | |
| 4007 // -- When all tasks claimed (both spaces) | |
| 4008 // and local work queue empty, | |
| 4009 // then in a loop do: | |
| 4010 // . check global overflow stack; steal a batch of oops and trace | |
| 4011 // . try to steal from other threads oif GOS is empty | |
| 4012 // . if neither is available, offer termination | |
| 4013 // -- Terminate and return result | |
| 4014 // | |
|
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4015 void CMSConcMarkingTask::work(uint worker_id) { |
| 0 | 4016 elapsedTimer _timer; |
| 4017 ResourceMark rm; | |
| 4018 HandleMark hm; | |
| 4019 | |
| 4020 DEBUG_ONLY(_collector->verify_overflow_empty();) | |
| 4021 | |
| 4022 // Before we begin work, our work queue should be empty | |
|
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4023 assert(work_queue(worker_id)->size() == 0, "Expected to be empty"); |
| 0 | 4024 // Scan the bitmap covering _cms_space, tracing through grey objects. |
| 4025 _timer.start(); | |
|
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4026 do_scan_and_mark(worker_id, _cms_space); |
| 0 | 4027 _timer.stop(); |
| 4028 if (PrintCMSStatistics != 0) { | |
| 4029 gclog_or_tty->print_cr("Finished cms space scanning in %dth thread: %3.3f sec", | |
|
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4030 worker_id, _timer.seconds()); |
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4031 // XXX: need xxx/xxx type of notation, two timers |
| 0 | 4032 } |
| 4033 | |
| 4034 // ... do work stealing | |
| 4035 _timer.reset(); | |
| 4036 _timer.start(); | |
|
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4037 do_work_steal(worker_id); |
| 0 | 4038 _timer.stop(); |
| 4039 if (PrintCMSStatistics != 0) { | |
| 4040 gclog_or_tty->print_cr("Finished work stealing 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 assert(_collector->_markStack.isEmpty(), "Should have been emptied"); | |
|
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4045 assert(work_queue(worker_id)->size() == 0, "Should have been emptied"); |
| 0 | 4046 // Note that under the current task protocol, the |
| 4047 // following assertion is true even of the spaces | |
| 4048 // expanded since the completion of the concurrent | |
| 4049 // marking. XXX This will likely change under a strict | |
| 4050 // ABORT semantics. | |
|
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4051 // After perm removal the comparison was changed to |
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4052 // greater than or equal to from strictly greater than. |
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4053 // Before perm removal the highest address sweep would |
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4054 // have been at the end of perm gen but now is at the |
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4055 // end of the tenured gen. |
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|
4056 assert(_global_finger >= _cms_space->end(), |
| 0 | 4057 "All tasks have been completed"); |
| 4058 DEBUG_ONLY(_collector->verify_overflow_empty();) | |
| 4059 } | |
| 4060 | |
| 4061 void CMSConcMarkingTask::bump_global_finger(HeapWord* f) { | |
| 4062 HeapWord* read = _global_finger; | |
| 4063 HeapWord* cur = read; | |
| 4064 while (f > read) { | |
| 4065 cur = read; | |
| 4066 read = (HeapWord*) Atomic::cmpxchg_ptr(f, &_global_finger, cur); | |
| 4067 if (cur == read) { | |
| 4068 // our cas succeeded | |
| 4069 assert(_global_finger >= f, "protocol consistency"); | |
| 4070 break; | |
| 4071 } | |
| 4072 } | |
| 4073 } | |
| 4074 | |
| 4075 // This is really inefficient, and should be redone by | |
| 4076 // using (not yet available) block-read and -write interfaces to the | |
| 4077 // stack and the work_queue. XXX FIX ME !!! | |
| 4078 bool CMSConcMarkingTask::get_work_from_overflow_stack(CMSMarkStack* ovflw_stk, | |
| 4079 OopTaskQueue* work_q) { | |
| 4080 // Fast lock-free check | |
| 4081 if (ovflw_stk->length() == 0) { | |
| 4082 return false; | |
| 4083 } | |
| 4084 assert(work_q->size() == 0, "Shouldn't steal"); | |
| 4085 MutexLockerEx ml(ovflw_stk->par_lock(), | |
| 4086 Mutex::_no_safepoint_check_flag); | |
| 4087 // Grab up to 1/4 the size of the work queue | |
|
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|
4088 size_t num = MIN2((size_t)(work_q->max_elems() - work_q->size())/4, |
| 0 | 4089 (size_t)ParGCDesiredObjsFromOverflowList); |
| 4090 num = MIN2(num, ovflw_stk->length()); | |
| 4091 for (int i = (int) num; i > 0; i--) { | |
| 4092 oop cur = ovflw_stk->pop(); | |
| 4093 assert(cur != NULL, "Counted wrong?"); | |
| 4094 work_q->push(cur); | |
| 4095 } | |
| 4096 return num > 0; | |
| 4097 } | |
| 4098 | |
| 4099 void CMSConcMarkingTask::do_scan_and_mark(int i, CompactibleFreeListSpace* sp) { | |
| 4100 SequentialSubTasksDone* pst = sp->conc_par_seq_tasks(); | |
| 4101 int n_tasks = pst->n_tasks(); | |
| 4102 // We allow that there may be no tasks to do here because | |
| 4103 // we are restarting after a stack overflow. | |
|
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4104 assert(pst->valid() || n_tasks == 0, "Uninitialized use?"); |
|
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4105 uint nth_task = 0; |
| 0 | 4106 |
|
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4107 HeapWord* aligned_start = sp->bottom(); |
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4108 if (sp->used_region().contains(_restart_addr)) { |
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4109 // Align down to a card boundary for the start of 0th task |
|
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4110 // for this space. |
|
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4111 aligned_start = |
|
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|
4112 (HeapWord*)align_size_down((uintptr_t)_restart_addr, |
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4113 CardTableModRefBS::card_size); |
|
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4114 } |
|
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4115 |
| 0 | 4116 size_t chunk_size = sp->marking_task_size(); |
| 4117 while (!pst->is_task_claimed(/* reference */ nth_task)) { | |
| 4118 // Having claimed the nth task in this space, | |
| 4119 // compute the chunk that it corresponds to: | |
|
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4120 MemRegion span = MemRegion(aligned_start + nth_task*chunk_size, |
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4121 aligned_start + (nth_task+1)*chunk_size); |
| 0 | 4122 // Try and bump the global finger via a CAS; |
| 4123 // note that we need to do the global finger bump | |
| 4124 // _before_ taking the intersection below, because | |
| 4125 // the task corresponding to that region will be | |
| 4126 // deemed done even if the used_region() expands | |
| 4127 // because of allocation -- as it almost certainly will | |
| 4128 // during start-up while the threads yield in the | |
| 4129 // closure below. | |
| 4130 HeapWord* finger = span.end(); | |
| 4131 bump_global_finger(finger); // atomically | |
| 4132 // There are null tasks here corresponding to chunks | |
| 4133 // beyond the "top" address of the space. | |
| 4134 span = span.intersection(sp->used_region()); | |
| 4135 if (!span.is_empty()) { // Non-null task | |
|
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4136 HeapWord* prev_obj; |
|
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|
4137 assert(!span.contains(_restart_addr) || nth_task == 0, |
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4138 "Inconsistency"); |
|
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4139 if (nth_task == 0) { |
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4140 // For the 0th task, we'll not need to compute a block_start. |
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4141 if (span.contains(_restart_addr)) { |
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4142 // In the case of a restart because of stack overflow, |
|
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4143 // we might additionally skip a chunk prefix. |
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4144 prev_obj = _restart_addr; |
| 0 | 4145 } else { |
|
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4146 prev_obj = span.start(); |
|
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|
4147 } |
|
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|
4148 } else { |
|
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|
4149 // We want to skip the first object because |
|
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4150 // the protocol is to scan any object in its entirety |
|
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4151 // that _starts_ in this span; a fortiori, any |
|
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4152 // object starting in an earlier span is scanned |
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4153 // as part of an earlier claimed task. |
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4154 // Below we use the "careful" version of block_start |
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4155 // so we do not try to navigate uninitialized objects. |
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4156 prev_obj = sp->block_start_careful(span.start()); |
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4157 // Below we use a variant of block_size that uses the |
|
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4158 // Printezis bits to avoid waiting for allocated |
|
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4159 // objects to become initialized/parsable. |
|
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|
4160 while (prev_obj < span.start()) { |
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4161 size_t sz = sp->block_size_no_stall(prev_obj, _collector); |
|
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4162 if (sz > 0) { |
|
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4163 prev_obj += sz; |
|
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4164 } else { |
|
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4165 // In this case we may end up doing a bit of redundant |
|
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4166 // scanning, but that appears unavoidable, short of |
|
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4167 // locking the free list locks; see bug 6324141. |
|
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4168 break; |
|
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|
4169 } |
| 0 | 4170 } |
| 4171 } | |
| 4172 if (prev_obj < span.end()) { | |
| 4173 MemRegion my_span = MemRegion(prev_obj, span.end()); | |
| 4174 // Do the marking work within a non-empty span -- | |
| 4175 // the last argument to the constructor indicates whether the | |
| 4176 // iteration should be incremental with periodic yields. | |
| 4177 Par_MarkFromRootsClosure cl(this, _collector, my_span, | |
| 4178 &_collector->_markBitMap, | |
| 4179 work_queue(i), | |
| 4180 &_collector->_markStack, | |
| 4181 _asynch); | |
| 4182 _collector->_markBitMap.iterate(&cl, my_span.start(), my_span.end()); | |
| 4183 } // else nothing to do for this task | |
| 4184 } // else nothing to do for this task | |
| 4185 } | |
| 4186 // We'd be tempted to assert here that since there are no | |
| 4187 // more tasks left to claim in this space, the global_finger | |
| 4188 // must exceed space->top() and a fortiori space->end(). However, | |
| 4189 // that would not quite be correct because the bumping of | |
| 4190 // global_finger occurs strictly after the claiming of a task, | |
| 4191 // so by the time we reach here the global finger may not yet | |
| 4192 // have been bumped up by the thread that claimed the last | |
| 4193 // task. | |
| 4194 pst->all_tasks_completed(); | |
| 4195 } | |
| 4196 | |
|
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4197 class Par_ConcMarkingClosure: public CMSOopClosure { |
|
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4198 private: |
|
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|
4199 CMSCollector* _collector; |
|
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|
4200 CMSConcMarkingTask* _task; |
| 0 | 4201 MemRegion _span; |
| 4202 CMSBitMap* _bit_map; | |
| 4203 CMSMarkStack* _overflow_stack; | |
| 4204 OopTaskQueue* _work_queue; | |
|
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4205 protected: |
|
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4206 DO_OOP_WORK_DEFN |
| 0 | 4207 public: |
|
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|
4208 Par_ConcMarkingClosure(CMSCollector* collector, CMSConcMarkingTask* task, OopTaskQueue* work_queue, |
|
6725
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|
4209 CMSBitMap* bit_map, CMSMarkStack* overflow_stack): |
|
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|
4210 CMSOopClosure(collector->ref_processor()), |
|
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|
4211 _collector(collector), |
|
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|
4212 _task(task), |
|
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|
4213 _span(collector->_span), |
| 0 | 4214 _work_queue(work_queue), |
| 4215 _bit_map(bit_map), | |
| 935 | 4216 _overflow_stack(overflow_stack) |
| 4217 { } | |
|
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4218 virtual void do_oop(oop* p); |
|
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4219 virtual void do_oop(narrowOop* p); |
|
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4220 |
| 0 | 4221 void trim_queue(size_t max); |
| 4222 void handle_stack_overflow(HeapWord* lost); | |
|
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|
4223 void do_yield_check() { |
|
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|
4224 if (_task->should_yield()) { |
|
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|
4225 _task->yield(); |
|
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|
4226 } |
|
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|
4227 } |
| 0 | 4228 }; |
| 4229 | |
|
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4230 // Grey object scanning during work stealing phase -- |
|
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4231 // the salient assumption here is that any references |
|
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4232 // that are in these stolen objects being scanned must |
|
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4233 // already have been initialized (else they would not have |
|
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|
4234 // been published), so we do not need to check for |
|
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|
4235 // uninitialized objects before pushing here. |
|
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4236 void Par_ConcMarkingClosure::do_oop(oop obj) { |
|
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4237 assert(obj->is_oop_or_null(true), "expected an oop or NULL"); |
|
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4238 HeapWord* addr = (HeapWord*)obj; |
| 0 | 4239 // Check if oop points into the CMS generation |
| 4240 // and is not marked | |
| 4241 if (_span.contains(addr) && !_bit_map->isMarked(addr)) { | |
| 4242 // a white object ... | |
| 4243 // If we manage to "claim" the object, by being the | |
| 4244 // first thread to mark it, then we push it on our | |
| 4245 // marking stack | |
| 4246 if (_bit_map->par_mark(addr)) { // ... now grey | |
| 4247 // push on work queue (grey set) | |
| 4248 bool simulate_overflow = false; | |
| 4249 NOT_PRODUCT( | |
| 4250 if (CMSMarkStackOverflowALot && | |
| 4251 _collector->simulate_overflow()) { | |
| 4252 // simulate a stack overflow | |
| 4253 simulate_overflow = true; | |
| 4254 } | |
| 4255 ) | |
| 4256 if (simulate_overflow || | |
|
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|
4257 !(_work_queue->push(obj) || _overflow_stack->par_push(obj))) { |
| 0 | 4258 // stack overflow |
| 4259 if (PrintCMSStatistics != 0) { | |
| 4260 gclog_or_tty->print_cr("CMS marking stack overflow (benign) at " | |
| 4261 SIZE_FORMAT, _overflow_stack->capacity()); | |
| 4262 } | |
| 4263 // We cannot assert that the overflow stack is full because | |
| 4264 // it may have been emptied since. | |
| 4265 assert(simulate_overflow || | |
| 4266 _work_queue->size() == _work_queue->max_elems(), | |
| 4267 "Else push should have succeeded"); | |
| 4268 handle_stack_overflow(addr); | |
| 4269 } | |
| 4270 } // Else, some other thread got there first | |
|
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|
4271 do_yield_check(); |
| 0 | 4272 } |
| 4273 } | |
| 4274 | |
|
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4275 void Par_ConcMarkingClosure::do_oop(oop* p) { Par_ConcMarkingClosure::do_oop_work(p); } |
|
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4276 void Par_ConcMarkingClosure::do_oop(narrowOop* p) { Par_ConcMarkingClosure::do_oop_work(p); } |
|
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|
4277 |
| 0 | 4278 void Par_ConcMarkingClosure::trim_queue(size_t max) { |
| 4279 while (_work_queue->size() > max) { | |
| 4280 oop new_oop; | |
| 4281 if (_work_queue->pop_local(new_oop)) { | |
| 4282 assert(new_oop->is_oop(), "Should be an oop"); | |
| 4283 assert(_bit_map->isMarked((HeapWord*)new_oop), "Grey object"); | |
| 4284 assert(_span.contains((HeapWord*)new_oop), "Not in span"); | |
| 4285 new_oop->oop_iterate(this); // do_oop() above | |
|
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diff
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|
4286 do_yield_check(); |
| 0 | 4287 } |
| 4288 } | |
| 4289 } | |
| 4290 | |
| 4291 // Upon stack overflow, we discard (part of) the stack, | |
| 4292 // remembering the least address amongst those discarded | |
| 4293 // in CMSCollector's _restart_address. | |
| 4294 void Par_ConcMarkingClosure::handle_stack_overflow(HeapWord* lost) { | |
| 4295 // We need to do this under a mutex to prevent other | |
|
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|
4296 // workers from interfering with the work done below. |
| 0 | 4297 MutexLockerEx ml(_overflow_stack->par_lock(), |
| 4298 Mutex::_no_safepoint_check_flag); | |
| 4299 // Remember the least grey address discarded | |
| 4300 HeapWord* ra = (HeapWord*)_overflow_stack->least_value(lost); | |
| 4301 _collector->lower_restart_addr(ra); | |
| 4302 _overflow_stack->reset(); // discard stack contents | |
| 4303 _overflow_stack->expand(); // expand the stack if possible | |
| 4304 } | |
| 4305 | |
| 4306 | |
| 4307 void CMSConcMarkingTask::do_work_steal(int i) { | |
| 4308 OopTaskQueue* work_q = work_queue(i); | |
| 4309 oop obj_to_scan; | |
| 4310 CMSBitMap* bm = &(_collector->_markBitMap); | |
| 4311 CMSMarkStack* ovflw = &(_collector->_markStack); | |
| 4312 int* seed = _collector->hash_seed(i); | |
|
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4313 Par_ConcMarkingClosure cl(_collector, this, work_q, bm, ovflw); |
| 0 | 4314 while (true) { |
| 4315 cl.trim_queue(0); | |
| 4316 assert(work_q->size() == 0, "Should have been emptied above"); | |
| 4317 if (get_work_from_overflow_stack(ovflw, work_q)) { | |
| 4318 // Can't assert below because the work obtained from the | |
| 4319 // overflow stack may already have been stolen from us. | |
| 4320 // assert(work_q->size() > 0, "Work from overflow stack"); | |
| 4321 continue; | |
| 4322 } else if (task_queues()->steal(i, seed, /* reference */ obj_to_scan)) { | |
| 4323 assert(obj_to_scan->is_oop(), "Should be an oop"); | |
| 4324 assert(bm->isMarked((HeapWord*)obj_to_scan), "Grey object"); | |
| 4325 obj_to_scan->oop_iterate(&cl); | |
|
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|
4326 } else if (terminator()->offer_termination(&_term_term)) { |
| 0 | 4327 assert(work_q->size() == 0, "Impossible!"); |
| 4328 break; | |
|
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|
4329 } else if (yielding() || should_yield()) { |
|
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|
4330 yield(); |
| 0 | 4331 } |
| 4332 } | |
| 4333 } | |
| 4334 | |
| 4335 // This is run by the CMS (coordinator) thread. | |
| 4336 void CMSConcMarkingTask::coordinator_yield() { | |
| 4337 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 4338 "CMS thread should hold CMS token"); | |
| 4339 // First give up the locks, then yield, then re-lock | |
| 4340 // We should probably use a constructor/destructor idiom to | |
| 4341 // do this unlock/lock or modify the MutexUnlocker class to | |
| 4342 // serve our purpose. XXX | |
| 4343 assert_lock_strong(_bit_map_lock); | |
| 4344 _bit_map_lock->unlock(); | |
| 4345 ConcurrentMarkSweepThread::desynchronize(true); | |
| 4346 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 4347 _collector->stopTimer(); | |
| 4348 if (PrintCMSStatistics != 0) { | |
| 4349 _collector->incrementYields(); | |
| 4350 } | |
| 4351 _collector->icms_wait(); | |
| 4352 | |
| 4353 // It is possible for whichever thread initiated the yield request | |
| 4354 // not to get a chance to wake up and take the bitmap lock between | |
| 4355 // this thread releasing it and reacquiring it. So, while the | |
| 4356 // should_yield() flag is on, let's sleep for a bit to give the | |
| 4357 // other thread a chance to wake up. The limit imposed on the number | |
| 4358 // of iterations is defensive, to avoid any unforseen circumstances | |
| 4359 // putting us into an infinite loop. Since it's always been this | |
| 4360 // (coordinator_yield()) method that was observed to cause the | |
| 4361 // problem, we are using a parameter (CMSCoordinatorYieldSleepCount) | |
| 4362 // which is by default non-zero. For the other seven methods that | |
| 4363 // also perform the yield operation, as are using a different | |
| 4364 // parameter (CMSYieldSleepCount) which is by default zero. This way we | |
| 4365 // can enable the sleeping for those methods too, if necessary. | |
| 4366 // See 6442774. | |
| 4367 // | |
| 4368 // We really need to reconsider the synchronization between the GC | |
| 4369 // thread and the yield-requesting threads in the future and we | |
| 4370 // should really use wait/notify, which is the recommended | |
| 4371 // way of doing this type of interaction. Additionally, we should | |
| 4372 // consolidate the eight methods that do the yield operation and they | |
| 14309 | 4373 // are almost identical into one for better maintainability and |
| 0 | 4374 // readability. See 6445193. |
| 4375 // | |
| 4376 // Tony 2006.06.29 | |
| 4377 for (unsigned i = 0; i < CMSCoordinatorYieldSleepCount && | |
|
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|
4378 ConcurrentMarkSweepThread::should_yield() && |
|
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|
4379 !CMSCollector::foregroundGCIsActive(); ++i) { |
| 0 | 4380 os::sleep(Thread::current(), 1, false); |
| 4381 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 4382 } | |
| 4383 | |
| 4384 ConcurrentMarkSweepThread::synchronize(true); | |
| 4385 _bit_map_lock->lock_without_safepoint_check(); | |
| 4386 _collector->startTimer(); | |
| 4387 } | |
| 4388 | |
| 4389 bool CMSCollector::do_marking_mt(bool asynch) { | |
| 1284 | 4390 assert(ConcGCThreads > 0 && conc_workers() != NULL, "precondition"); |
|
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|
4391 int num_workers = AdaptiveSizePolicy::calc_active_conc_workers( |
|
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|
4392 conc_workers()->total_workers(), |
|
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|
4393 conc_workers()->active_workers(), |
|
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|
4394 Threads::number_of_non_daemon_threads()); |
|
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|
4395 conc_workers()->set_active_workers(num_workers); |
| 0 | 4396 |
| 4397 CompactibleFreeListSpace* cms_space = _cmsGen->cmsSpace(); | |
| 4398 | |
|
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|
4399 CMSConcMarkingTask tsk(this, |
|
8b10f48633dc
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|
4400 cms_space, |
|
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|
4401 asynch, |
|
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|
4402 conc_workers(), |
|
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|
4403 task_queues()); |
| 0 | 4404 |
| 4405 // Since the actual number of workers we get may be different | |
| 4406 // from the number we requested above, do we need to do anything different | |
| 4407 // below? In particular, may be we need to subclass the SequantialSubTasksDone | |
| 4408 // class?? XXX | |
| 4409 cms_space ->initialize_sequential_subtasks_for_marking(num_workers); | |
| 4410 | |
| 4411 // Refs discovery is already non-atomic. | |
| 4412 assert(!ref_processor()->discovery_is_atomic(), "Should be non-atomic"); | |
|
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|
4413 assert(ref_processor()->discovery_is_mt(), "Discovery should be MT"); |
| 0 | 4414 conc_workers()->start_task(&tsk); |
| 4415 while (tsk.yielded()) { | |
| 4416 tsk.coordinator_yield(); | |
| 4417 conc_workers()->continue_task(&tsk); | |
| 4418 } | |
| 4419 // If the task was aborted, _restart_addr will be non-NULL | |
| 4420 assert(tsk.completed() || _restart_addr != NULL, "Inconsistency"); | |
| 4421 while (_restart_addr != NULL) { | |
| 4422 // XXX For now we do not make use of ABORTED state and have not | |
| 4423 // yet implemented the right abort semantics (even in the original | |
| 4424 // single-threaded CMS case). That needs some more investigation | |
| 4425 // and is deferred for now; see CR# TBF. 07252005YSR. XXX | |
| 4426 assert(!CMSAbortSemantics || tsk.aborted(), "Inconsistency"); | |
| 4427 // If _restart_addr is non-NULL, a marking stack overflow | |
| 605 | 4428 // occurred; we need to do a fresh marking iteration from the |
| 0 | 4429 // indicated restart address. |
| 4430 if (_foregroundGCIsActive && asynch) { | |
| 4431 // We may be running into repeated stack overflows, having | |
| 4432 // reached the limit of the stack size, while making very | |
| 4433 // slow forward progress. It may be best to bail out and | |
| 4434 // let the foreground collector do its job. | |
| 4435 // Clear _restart_addr, so that foreground GC | |
| 4436 // works from scratch. This avoids the headache of | |
| 4437 // a "rescan" which would otherwise be needed because | |
| 4438 // of the dirty mod union table & card table. | |
| 4439 _restart_addr = NULL; | |
| 4440 return false; | |
| 4441 } | |
| 4442 // Adjust the task to restart from _restart_addr | |
| 4443 tsk.reset(_restart_addr); | |
| 4444 cms_space ->initialize_sequential_subtasks_for_marking(num_workers, | |
| 4445 _restart_addr); | |
| 4446 _restart_addr = NULL; | |
| 4447 // Get the workers going again | |
| 4448 conc_workers()->start_task(&tsk); | |
| 4449 while (tsk.yielded()) { | |
| 4450 tsk.coordinator_yield(); | |
| 4451 conc_workers()->continue_task(&tsk); | |
| 4452 } | |
| 4453 } | |
| 4454 assert(tsk.completed(), "Inconsistency"); | |
| 4455 assert(tsk.result() == true, "Inconsistency"); | |
| 4456 return true; | |
| 4457 } | |
| 4458 | |
| 4459 bool CMSCollector::do_marking_st(bool asynch) { | |
| 4460 ResourceMark rm; | |
| 4461 HandleMark hm; | |
| 4462 | |
|
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|
4463 // Temporarily make refs discovery single threaded (non-MT) |
|
92da084fefc9
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|
4464 ReferenceProcessorMTDiscoveryMutator rp_mut_discovery(ref_processor(), false); |
| 0 | 4465 MarkFromRootsClosure markFromRootsClosure(this, _span, &_markBitMap, |
|
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|
4466 &_markStack, CMSYield && asynch); |
| 0 | 4467 // the last argument to iterate indicates whether the iteration |
| 4468 // should be incremental with periodic yields. | |
| 4469 _markBitMap.iterate(&markFromRootsClosure); | |
| 4470 // If _restart_addr is non-NULL, a marking stack overflow | |
| 605 | 4471 // occurred; we need to do a fresh iteration from the |
| 0 | 4472 // indicated restart address. |
| 4473 while (_restart_addr != NULL) { | |
| 4474 if (_foregroundGCIsActive && asynch) { | |
| 4475 // We may be running into repeated stack overflows, having | |
| 4476 // reached the limit of the stack size, while making very | |
| 4477 // slow forward progress. It may be best to bail out and | |
| 4478 // let the foreground collector do its job. | |
| 4479 // Clear _restart_addr, so that foreground GC | |
| 4480 // works from scratch. This avoids the headache of | |
| 4481 // a "rescan" which would otherwise be needed because | |
| 4482 // of the dirty mod union table & card table. | |
| 4483 _restart_addr = NULL; | |
| 4484 return false; // indicating failure to complete marking | |
| 4485 } | |
| 4486 // Deal with stack overflow: | |
| 4487 // we restart marking from _restart_addr | |
| 4488 HeapWord* ra = _restart_addr; | |
| 4489 markFromRootsClosure.reset(ra); | |
| 4490 _restart_addr = NULL; | |
| 4491 _markBitMap.iterate(&markFromRootsClosure, ra, _span.end()); | |
| 4492 } | |
| 4493 return true; | |
| 4494 } | |
| 4495 | |
| 4496 void CMSCollector::preclean() { | |
| 4497 check_correct_thread_executing(); | |
| 4498 assert(Thread::current()->is_ConcurrentGC_thread(), "Wrong thread"); | |
| 4499 verify_work_stacks_empty(); | |
| 4500 verify_overflow_empty(); | |
| 4501 _abort_preclean = false; | |
| 4502 if (CMSPrecleaningEnabled) { | |
|
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|
4503 if (!CMSEdenChunksRecordAlways) { |
|
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|
4504 _eden_chunk_index = 0; |
|
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|
4505 } |
| 0 | 4506 size_t used = get_eden_used(); |
| 4507 size_t capacity = get_eden_capacity(); | |
| 4508 // Don't start sampling unless we will get sufficiently | |
| 4509 // many samples. | |
| 4510 if (used < (capacity/(CMSScheduleRemarkSamplingRatio * 100) | |
| 4511 * CMSScheduleRemarkEdenPenetration)) { | |
| 4512 _start_sampling = true; | |
| 4513 } else { | |
| 4514 _start_sampling = false; | |
| 4515 } | |
| 4516 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
| 4517 CMSPhaseAccounting pa(this, "preclean", !PrintGCDetails); | |
| 4518 preclean_work(CMSPrecleanRefLists1, CMSPrecleanSurvivors1); | |
| 4519 } | |
| 4520 CMSTokenSync x(true); // is cms thread | |
| 4521 if (CMSPrecleaningEnabled) { | |
| 4522 sample_eden(); | |
| 4523 _collectorState = AbortablePreclean; | |
| 4524 } else { | |
| 4525 _collectorState = FinalMarking; | |
| 4526 } | |
| 4527 verify_work_stacks_empty(); | |
| 4528 verify_overflow_empty(); | |
| 4529 } | |
| 4530 | |
| 4531 // Try and schedule the remark such that young gen | |
| 4532 // occupancy is CMSScheduleRemarkEdenPenetration %. | |
| 4533 void CMSCollector::abortable_preclean() { | |
| 4534 check_correct_thread_executing(); | |
| 4535 assert(CMSPrecleaningEnabled, "Inconsistent control state"); | |
| 4536 assert(_collectorState == AbortablePreclean, "Inconsistent control state"); | |
| 4537 | |
| 4538 // If Eden's current occupancy is below this threshold, | |
| 4539 // immediately schedule the remark; else preclean | |
| 4540 // past the next scavenge in an effort to | |
| 14309 | 4541 // schedule the pause as described above. By choosing |
| 0 | 4542 // CMSScheduleRemarkEdenSizeThreshold >= max eden size |
| 4543 // we will never do an actual abortable preclean cycle. | |
| 4544 if (get_eden_used() > CMSScheduleRemarkEdenSizeThreshold) { | |
| 4545 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
| 4546 CMSPhaseAccounting pa(this, "abortable-preclean", !PrintGCDetails); | |
| 4547 // We need more smarts in the abortable preclean | |
| 4548 // loop below to deal with cases where allocation | |
| 4549 // in young gen is very very slow, and our precleaning | |
| 4550 // is running a losing race against a horde of | |
| 4551 // mutators intent on flooding us with CMS updates | |
| 4552 // (dirty cards). | |
| 4553 // One, admittedly dumb, strategy is to give up | |
| 4554 // after a certain number of abortable precleaning loops | |
| 4555 // or after a certain maximum time. We want to make | |
| 4556 // this smarter in the next iteration. | |
| 4557 // XXX FIX ME!!! YSR | |
| 4558 size_t loops = 0, workdone = 0, cumworkdone = 0, waited = 0; | |
| 4559 while (!(should_abort_preclean() || | |
| 4560 ConcurrentMarkSweepThread::should_terminate())) { | |
| 4561 workdone = preclean_work(CMSPrecleanRefLists2, CMSPrecleanSurvivors2); | |
| 4562 cumworkdone += workdone; | |
| 4563 loops++; | |
| 4564 // Voluntarily terminate abortable preclean phase if we have | |
| 4565 // been at it for too long. | |
| 4566 if ((CMSMaxAbortablePrecleanLoops != 0) && | |
| 4567 loops >= CMSMaxAbortablePrecleanLoops) { | |
| 4568 if (PrintGCDetails) { | |
| 4569 gclog_or_tty->print(" CMS: abort preclean due to loops "); | |
| 4570 } | |
| 4571 break; | |
| 4572 } | |
| 4573 if (pa.wallclock_millis() > CMSMaxAbortablePrecleanTime) { | |
| 4574 if (PrintGCDetails) { | |
| 4575 gclog_or_tty->print(" CMS: abort preclean due to time "); | |
| 4576 } | |
| 4577 break; | |
| 4578 } | |
| 4579 // If we are doing little work each iteration, we should | |
| 4580 // take a short break. | |
| 4581 if (workdone < CMSAbortablePrecleanMinWorkPerIteration) { | |
| 4582 // Sleep for some time, waiting for work to accumulate | |
| 4583 stopTimer(); | |
| 4584 cmsThread()->wait_on_cms_lock(CMSAbortablePrecleanWaitMillis); | |
| 4585 startTimer(); | |
| 4586 waited++; | |
| 4587 } | |
| 4588 } | |
| 4589 if (PrintCMSStatistics > 0) { | |
| 4590 gclog_or_tty->print(" [%d iterations, %d waits, %d cards)] ", | |
| 4591 loops, waited, cumworkdone); | |
| 4592 } | |
| 4593 } | |
| 4594 CMSTokenSync x(true); // is cms thread | |
| 4595 if (_collectorState != Idling) { | |
| 4596 assert(_collectorState == AbortablePreclean, | |
| 4597 "Spontaneous state transition?"); | |
| 4598 _collectorState = FinalMarking; | |
| 4599 } // Else, a foreground collection completed this CMS cycle. | |
| 4600 return; | |
| 4601 } | |
| 4602 | |
| 4603 // Respond to an Eden sampling opportunity | |
| 4604 void CMSCollector::sample_eden() { | |
| 4605 // Make sure a young gc cannot sneak in between our | |
| 4606 // reading and recording of a sample. | |
| 4607 assert(Thread::current()->is_ConcurrentGC_thread(), | |
| 4608 "Only the cms thread may collect Eden samples"); | |
| 4609 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 4610 "Should collect samples while holding CMS token"); | |
| 4611 if (!_start_sampling) { | |
| 4612 return; | |
| 4613 } | |
|
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|
4614 // When CMSEdenChunksRecordAlways is true, the eden chunk array |
|
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|
4615 // is populated by the young generation. |
|
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|
4616 if (_eden_chunk_array != NULL && !CMSEdenChunksRecordAlways) { |
| 0 | 4617 if (_eden_chunk_index < _eden_chunk_capacity) { |
| 4618 _eden_chunk_array[_eden_chunk_index] = *_top_addr; // take sample | |
| 4619 assert(_eden_chunk_array[_eden_chunk_index] <= *_end_addr, | |
| 4620 "Unexpected state of Eden"); | |
| 4621 // We'd like to check that what we just sampled is an oop-start address; | |
| 4622 // however, we cannot do that here since the object may not yet have been | |
| 4623 // initialized. So we'll instead do the check when we _use_ this sample | |
| 4624 // later. | |
| 4625 if (_eden_chunk_index == 0 || | |
| 4626 (pointer_delta(_eden_chunk_array[_eden_chunk_index], | |
| 4627 _eden_chunk_array[_eden_chunk_index-1]) | |
| 4628 >= CMSSamplingGrain)) { | |
| 4629 _eden_chunk_index++; // commit sample | |
| 4630 } | |
| 4631 } | |
| 4632 } | |
| 4633 if ((_collectorState == AbortablePreclean) && !_abort_preclean) { | |
| 4634 size_t used = get_eden_used(); | |
| 4635 size_t capacity = get_eden_capacity(); | |
| 4636 assert(used <= capacity, "Unexpected state of Eden"); | |
| 4637 if (used > (capacity/100 * CMSScheduleRemarkEdenPenetration)) { | |
| 4638 _abort_preclean = true; | |
| 4639 } | |
| 4640 } | |
| 4641 } | |
| 4642 | |
| 4643 | |
| 4644 size_t CMSCollector::preclean_work(bool clean_refs, bool clean_survivor) { | |
| 4645 assert(_collectorState == Precleaning || | |
| 4646 _collectorState == AbortablePreclean, "incorrect state"); | |
| 4647 ResourceMark rm; | |
| 4648 HandleMark hm; | |
|
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4649 |
|
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|
4650 // Precleaning is currently not MT but the reference processor |
|
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4651 // may be set for MT. Disable it temporarily here. |
|
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4652 ReferenceProcessor* rp = ref_processor(); |
|
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|
4653 ReferenceProcessorMTDiscoveryMutator rp_mut_discovery(rp, false); |
|
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|
4654 |
| 0 | 4655 // Do one pass of scrubbing the discovered reference lists |
| 4656 // to remove any reference objects with strongly-reachable | |
| 4657 // referents. | |
| 4658 if (clean_refs) { | |
| 4659 CMSPrecleanRefsYieldClosure yield_cl(this); | |
| 4660 assert(rp->span().equals(_span), "Spans should be equal"); | |
| 4661 CMSKeepAliveClosure keep_alive(this, _span, &_markBitMap, | |
|
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4662 &_markStack, true /* preclean */); |
| 0 | 4663 CMSDrainMarkingStackClosure complete_trace(this, |
|
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4664 _span, &_markBitMap, &_markStack, |
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4665 &keep_alive, true /* preclean */); |
| 0 | 4666 |
| 4667 // We don't want this step to interfere with a young | |
| 4668 // collection because we don't want to take CPU | |
| 4669 // or memory bandwidth away from the young GC threads | |
| 4670 // (which may be as many as there are CPUs). | |
| 4671 // Note that we don't need to protect ourselves from | |
| 4672 // interference with mutators because they can't | |
| 4673 // manipulate the discovered reference lists nor affect | |
| 4674 // the computed reachability of the referents, the | |
| 4675 // only properties manipulated by the precleaning | |
| 4676 // of these reference lists. | |
| 4677 stopTimer(); | |
| 4678 CMSTokenSyncWithLocks x(true /* is cms thread */, | |
| 4679 bitMapLock()); | |
| 4680 startTimer(); | |
| 4681 sample_eden(); | |
| 935 | 4682 |
| 0 | 4683 // The following will yield to allow foreground |
| 4684 // collection to proceed promptly. XXX YSR: | |
| 4685 // The code in this method may need further | |
| 4686 // tweaking for better performance and some restructuring | |
| 4687 // for cleaner interfaces. | |
| 10405 | 4688 GCTimer *gc_timer = NULL; // Currently not tracing concurrent phases |
| 0 | 4689 rp->preclean_discovered_references( |
| 10405 | 4690 rp->is_alive_non_header(), &keep_alive, &complete_trace, &yield_cl, |
| 4691 gc_timer); | |
| 0 | 4692 } |
| 4693 | |
| 4694 if (clean_survivor) { // preclean the active survivor space(s) | |
| 4695 assert(_young_gen->kind() == Generation::DefNew || | |
| 4696 _young_gen->kind() == Generation::ParNew || | |
| 4697 _young_gen->kind() == Generation::ASParNew, | |
| 4698 "incorrect type for cast"); | |
| 4699 DefNewGeneration* dng = (DefNewGeneration*)_young_gen; | |
| 4700 PushAndMarkClosure pam_cl(this, _span, ref_processor(), | |
| 4701 &_markBitMap, &_modUnionTable, | |
|
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4702 &_markStack, true /* precleaning phase */); |
| 0 | 4703 stopTimer(); |
| 4704 CMSTokenSyncWithLocks ts(true /* is cms thread */, | |
| 4705 bitMapLock()); | |
| 4706 startTimer(); | |
| 4707 unsigned int before_count = | |
| 4708 GenCollectedHeap::heap()->total_collections(); | |
| 4709 SurvivorSpacePrecleanClosure | |
| 4710 sss_cl(this, _span, &_markBitMap, &_markStack, | |
| 4711 &pam_cl, before_count, CMSYield); | |
| 4712 dng->from()->object_iterate_careful(&sss_cl); | |
| 4713 dng->to()->object_iterate_careful(&sss_cl); | |
| 4714 } | |
| 4715 MarkRefsIntoAndScanClosure | |
| 4716 mrias_cl(_span, ref_processor(), &_markBitMap, &_modUnionTable, | |
|
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|
4717 &_markStack, this, CMSYield, |
| 0 | 4718 true /* precleaning phase */); |
| 4719 // CAUTION: The following closure has persistent state that may need to | |
| 4720 // be reset upon a decrease in the sequence of addresses it | |
| 4721 // processes. | |
| 4722 ScanMarkedObjectsAgainCarefullyClosure | |
| 4723 smoac_cl(this, _span, | |
|
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4724 &_markBitMap, &_markStack, &mrias_cl, CMSYield); |
| 0 | 4725 |
| 4726 // Preclean dirty cards in ModUnionTable and CardTable using | |
| 4727 // appropriate convergence criterion; | |
| 4728 // repeat CMSPrecleanIter times unless we find that | |
| 4729 // we are losing. | |
| 4730 assert(CMSPrecleanIter < 10, "CMSPrecleanIter is too large"); | |
| 4731 assert(CMSPrecleanNumerator < CMSPrecleanDenominator, | |
| 4732 "Bad convergence multiplier"); | |
| 4733 assert(CMSPrecleanThreshold >= 100, | |
| 4734 "Unreasonably low CMSPrecleanThreshold"); | |
| 4735 | |
| 4736 size_t numIter, cumNumCards, lastNumCards, curNumCards; | |
| 4737 for (numIter = 0, cumNumCards = lastNumCards = curNumCards = 0; | |
| 4738 numIter < CMSPrecleanIter; | |
| 4739 numIter++, lastNumCards = curNumCards, cumNumCards += curNumCards) { | |
| 4740 curNumCards = preclean_mod_union_table(_cmsGen, &smoac_cl); | |
| 4741 if (Verbose && PrintGCDetails) { | |
| 4742 gclog_or_tty->print(" (modUnionTable: %d cards)", curNumCards); | |
| 4743 } | |
| 4744 // Either there are very few dirty cards, so re-mark | |
| 4745 // pause will be small anyway, or our pre-cleaning isn't | |
| 4746 // that much faster than the rate at which cards are being | |
| 4747 // dirtied, so we might as well stop and re-mark since | |
| 4748 // precleaning won't improve our re-mark time by much. | |
| 4749 if (curNumCards <= CMSPrecleanThreshold || | |
| 4750 (numIter > 0 && | |
| 4751 (curNumCards * CMSPrecleanDenominator > | |
| 4752 lastNumCards * CMSPrecleanNumerator))) { | |
| 4753 numIter++; | |
| 4754 cumNumCards += curNumCards; | |
| 4755 break; | |
| 4756 } | |
| 4757 } | |
|
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4758 |
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4759 preclean_klasses(&mrias_cl, _cmsGen->freelistLock()); |
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4760 |
| 0 | 4761 curNumCards = preclean_card_table(_cmsGen, &smoac_cl); |
| 4762 cumNumCards += curNumCards; | |
| 4763 if (PrintGCDetails && PrintCMSStatistics != 0) { | |
| 4764 gclog_or_tty->print_cr(" (cardTable: %d cards, re-scanned %d cards, %d iterations)", | |
| 4765 curNumCards, cumNumCards, numIter); | |
| 4766 } | |
| 4767 return cumNumCards; // as a measure of useful work done | |
| 4768 } | |
| 4769 | |
| 4770 // PRECLEANING NOTES: | |
| 4771 // Precleaning involves: | |
| 4772 // . reading the bits of the modUnionTable and clearing the set bits. | |
| 4773 // . For the cards corresponding to the set bits, we scan the | |
| 4774 // objects on those cards. This means we need the free_list_lock | |
| 4775 // so that we can safely iterate over the CMS space when scanning | |
| 4776 // for oops. | |
| 4777 // . When we scan the objects, we'll be both reading and setting | |
| 4778 // marks in the marking bit map, so we'll need the marking bit map. | |
| 4779 // . For protecting _collector_state transitions, we take the CGC_lock. | |
| 4780 // Note that any races in the reading of of card table entries by the | |
| 4781 // CMS thread on the one hand and the clearing of those entries by the | |
| 4782 // VM thread or the setting of those entries by the mutator threads on the | |
| 4783 // other are quite benign. However, for efficiency it makes sense to keep | |
| 4784 // the VM thread from racing with the CMS thread while the latter is | |
| 4785 // dirty card info to the modUnionTable. We therefore also use the | |
| 4786 // CGC_lock to protect the reading of the card table and the mod union | |
| 4787 // table by the CM thread. | |
| 4788 // . We run concurrently with mutator updates, so scanning | |
| 4789 // needs to be done carefully -- we should not try to scan | |
| 4790 // potentially uninitialized objects. | |
| 4791 // | |
| 4792 // Locking strategy: While holding the CGC_lock, we scan over and | |
| 4793 // reset a maximal dirty range of the mod union / card tables, then lock | |
| 4794 // the free_list_lock and bitmap lock to do a full marking, then | |
| 4795 // release these locks; and repeat the cycle. This allows for a | |
| 4796 // certain amount of fairness in the sharing of these locks between | |
| 4797 // the CMS collector on the one hand, and the VM thread and the | |
| 4798 // mutators on the other. | |
| 4799 | |
| 4800 // NOTE: preclean_mod_union_table() and preclean_card_table() | |
| 4801 // further below are largely identical; if you need to modify | |
| 4802 // one of these methods, please check the other method too. | |
| 4803 | |
| 4804 size_t CMSCollector::preclean_mod_union_table( | |
| 4805 ConcurrentMarkSweepGeneration* gen, | |
| 4806 ScanMarkedObjectsAgainCarefullyClosure* cl) { | |
| 4807 verify_work_stacks_empty(); | |
| 4808 verify_overflow_empty(); | |
| 4809 | |
| 4810 // strategy: starting with the first card, accumulate contiguous | |
| 4811 // ranges of dirty cards; clear these cards, then scan the region | |
| 4812 // covered by these cards. | |
| 4813 | |
| 4814 // Since all of the MUT is committed ahead, we can just use | |
| 4815 // that, in case the generations expand while we are precleaning. | |
| 4816 // It might also be fine to just use the committed part of the | |
| 4817 // generation, but we might potentially miss cards when the | |
| 4818 // generation is rapidly expanding while we are in the midst | |
| 4819 // of precleaning. | |
| 4820 HeapWord* startAddr = gen->reserved().start(); | |
| 4821 HeapWord* endAddr = gen->reserved().end(); | |
| 4822 | |
| 4823 cl->setFreelistLock(gen->freelistLock()); // needed for yielding | |
| 4824 | |
| 4825 size_t numDirtyCards, cumNumDirtyCards; | |
| 4826 HeapWord *nextAddr, *lastAddr; | |
| 4827 for (cumNumDirtyCards = numDirtyCards = 0, | |
| 4828 nextAddr = lastAddr = startAddr; | |
| 4829 nextAddr < endAddr; | |
| 4830 nextAddr = lastAddr, cumNumDirtyCards += numDirtyCards) { | |
| 4831 | |
| 4832 ResourceMark rm; | |
| 4833 HandleMark hm; | |
| 4834 | |
| 4835 MemRegion dirtyRegion; | |
| 4836 { | |
| 4837 stopTimer(); | |
| 935 | 4838 // Potential yield point |
| 0 | 4839 CMSTokenSync ts(true); |
| 4840 startTimer(); | |
| 4841 sample_eden(); | |
| 4842 // Get dirty region starting at nextOffset (inclusive), | |
| 4843 // simultaneously clearing it. | |
| 4844 dirtyRegion = | |
| 4845 _modUnionTable.getAndClearMarkedRegion(nextAddr, endAddr); | |
| 4846 assert(dirtyRegion.start() >= nextAddr, | |
| 4847 "returned region inconsistent?"); | |
| 4848 } | |
| 4849 // Remember where the next search should begin. | |
| 4850 // The returned region (if non-empty) is a right open interval, | |
| 4851 // so lastOffset is obtained from the right end of that | |
| 4852 // interval. | |
| 4853 lastAddr = dirtyRegion.end(); | |
| 4854 // Should do something more transparent and less hacky XXX | |
| 4855 numDirtyCards = | |
| 4856 _modUnionTable.heapWordDiffToOffsetDiff(dirtyRegion.word_size()); | |
| 4857 | |
| 4858 // We'll scan the cards in the dirty region (with periodic | |
| 4859 // yields for foreground GC as needed). | |
| 4860 if (!dirtyRegion.is_empty()) { | |
| 4861 assert(numDirtyCards > 0, "consistency check"); | |
| 4862 HeapWord* stop_point = NULL; | |
|
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4863 stopTimer(); |
| 935 | 4864 // Potential yield point |
|
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4865 CMSTokenSyncWithLocks ts(true, gen->freelistLock(), |
|
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|
4866 bitMapLock()); |
|
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|
4867 startTimer(); |
| 0 | 4868 { |
| 4869 verify_work_stacks_empty(); | |
| 4870 verify_overflow_empty(); | |
| 4871 sample_eden(); | |
| 4872 stop_point = | |
| 4873 gen->cmsSpace()->object_iterate_careful_m(dirtyRegion, cl); | |
| 4874 } | |
| 4875 if (stop_point != NULL) { | |
| 4876 // The careful iteration stopped early either because it found an | |
| 4877 // uninitialized object, or because we were in the midst of an | |
| 4878 // "abortable preclean", which should now be aborted. Redirty | |
| 4879 // the bits corresponding to the partially-scanned or unscanned | |
| 4880 // cards. We'll either restart at the next block boundary or | |
| 4881 // abort the preclean. | |
|
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4882 assert((_collectorState == AbortablePreclean && should_abort_preclean()), |
|
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4883 "Should only be AbortablePreclean."); |
| 0 | 4884 _modUnionTable.mark_range(MemRegion(stop_point, dirtyRegion.end())); |
| 4885 if (should_abort_preclean()) { | |
| 4886 break; // out of preclean loop | |
| 4887 } else { | |
| 4888 // Compute the next address at which preclean should pick up; | |
| 4889 // might need bitMapLock in order to read P-bits. | |
| 4890 lastAddr = next_card_start_after_block(stop_point); | |
| 4891 } | |
| 4892 } | |
| 4893 } else { | |
| 4894 assert(lastAddr == endAddr, "consistency check"); | |
| 4895 assert(numDirtyCards == 0, "consistency check"); | |
| 4896 break; | |
| 4897 } | |
| 4898 } | |
| 4899 verify_work_stacks_empty(); | |
| 4900 verify_overflow_empty(); | |
| 4901 return cumNumDirtyCards; | |
| 4902 } | |
| 4903 | |
| 4904 // NOTE: preclean_mod_union_table() above and preclean_card_table() | |
| 4905 // below are largely identical; if you need to modify | |
| 4906 // one of these methods, please check the other method too. | |
| 4907 | |
| 4908 size_t CMSCollector::preclean_card_table(ConcurrentMarkSweepGeneration* gen, | |
| 4909 ScanMarkedObjectsAgainCarefullyClosure* cl) { | |
| 4910 // strategy: it's similar to precleamModUnionTable above, in that | |
| 4911 // we accumulate contiguous ranges of dirty cards, mark these cards | |
| 4912 // precleaned, then scan the region covered by these cards. | |
| 4913 HeapWord* endAddr = (HeapWord*)(gen->_virtual_space.high()); | |
| 4914 HeapWord* startAddr = (HeapWord*)(gen->_virtual_space.low()); | |
| 4915 | |
| 4916 cl->setFreelistLock(gen->freelistLock()); // needed for yielding | |
| 4917 | |
| 4918 size_t numDirtyCards, cumNumDirtyCards; | |
| 4919 HeapWord *lastAddr, *nextAddr; | |
| 4920 | |
| 4921 for (cumNumDirtyCards = numDirtyCards = 0, | |
| 4922 nextAddr = lastAddr = startAddr; | |
| 4923 nextAddr < endAddr; | |
| 4924 nextAddr = lastAddr, cumNumDirtyCards += numDirtyCards) { | |
| 4925 | |
| 4926 ResourceMark rm; | |
| 4927 HandleMark hm; | |
| 4928 | |
| 4929 MemRegion dirtyRegion; | |
| 4930 { | |
| 4931 // See comments in "Precleaning notes" above on why we | |
| 4932 // do this locking. XXX Could the locking overheads be | |
| 4933 // too high when dirty cards are sparse? [I don't think so.] | |
| 4934 stopTimer(); | |
| 4935 CMSTokenSync x(true); // is cms thread | |
| 4936 startTimer(); | |
| 4937 sample_eden(); | |
| 4938 // Get and clear dirty region from card table | |
|
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4939 dirtyRegion = _ct->ct_bs()->dirty_card_range_after_reset( |
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4940 MemRegion(nextAddr, endAddr), |
|
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|
4941 true, |
|
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4942 CardTableModRefBS::precleaned_card_val()); |
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4943 |
| 0 | 4944 assert(dirtyRegion.start() >= nextAddr, |
| 4945 "returned region inconsistent?"); | |
| 4946 } | |
| 4947 lastAddr = dirtyRegion.end(); | |
| 4948 numDirtyCards = | |
| 4949 dirtyRegion.word_size()/CardTableModRefBS::card_size_in_words; | |
| 4950 | |
| 4951 if (!dirtyRegion.is_empty()) { | |
| 4952 stopTimer(); | |
| 4953 CMSTokenSyncWithLocks ts(true, gen->freelistLock(), bitMapLock()); | |
| 4954 startTimer(); | |
| 4955 sample_eden(); | |
| 4956 verify_work_stacks_empty(); | |
| 4957 verify_overflow_empty(); | |
| 4958 HeapWord* stop_point = | |
| 4959 gen->cmsSpace()->object_iterate_careful_m(dirtyRegion, cl); | |
| 4960 if (stop_point != NULL) { | |
|
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4961 assert((_collectorState == AbortablePreclean && should_abort_preclean()), |
|
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4962 "Should only be AbortablePreclean."); |
| 0 | 4963 _ct->ct_bs()->invalidate(MemRegion(stop_point, dirtyRegion.end())); |
| 4964 if (should_abort_preclean()) { | |
| 4965 break; // out of preclean loop | |
| 4966 } else { | |
| 4967 // Compute the next address at which preclean should pick up. | |
| 4968 lastAddr = next_card_start_after_block(stop_point); | |
| 4969 } | |
| 4970 } | |
| 4971 } else { | |
| 4972 break; | |
| 4973 } | |
| 4974 } | |
| 4975 verify_work_stacks_empty(); | |
| 4976 verify_overflow_empty(); | |
| 4977 return cumNumDirtyCards; | |
| 4978 } | |
| 4979 | |
|
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4980 class PrecleanKlassClosure : public KlassClosure { |
|
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4981 CMKlassClosure _cm_klass_closure; |
|
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4982 public: |
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4983 PrecleanKlassClosure(OopClosure* oop_closure) : _cm_klass_closure(oop_closure) {} |
|
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4984 void do_klass(Klass* k) { |
|
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4985 if (k->has_accumulated_modified_oops()) { |
|
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4986 k->clear_accumulated_modified_oops(); |
|
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4987 |
|
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4988 _cm_klass_closure.do_klass(k); |
|
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4989 } |
|
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|
4990 } |
|
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|
4991 }; |
|
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4992 |
|
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4993 // The freelist lock is needed to prevent asserts, is it really needed? |
|
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4994 void CMSCollector::preclean_klasses(MarkRefsIntoAndScanClosure* cl, Mutex* freelistLock) { |
|
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4995 |
|
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4996 cl->set_freelistLock(freelistLock); |
|
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4997 |
|
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4998 CMSTokenSyncWithLocks ts(true, freelistLock, bitMapLock()); |
|
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4999 |
|
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5000 // SSS: Add equivalent to ScanMarkedObjectsAgainCarefullyClosure::do_yield_check and should_abort_preclean? |
|
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5001 // SSS: We should probably check if precleaning should be aborted, at suitable intervals? |
|
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5002 PrecleanKlassClosure preclean_klass_closure(cl); |
|
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5003 ClassLoaderDataGraph::classes_do(&preclean_klass_closure); |
|
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5004 |
|
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5005 verify_work_stacks_empty(); |
|
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5006 verify_overflow_empty(); |
|
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5007 } |
|
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5008 |
| 0 | 5009 void CMSCollector::checkpointRootsFinal(bool asynch, |
| 5010 bool clear_all_soft_refs, bool init_mark_was_synchronous) { | |
| 5011 assert(_collectorState == FinalMarking, "incorrect state transition?"); | |
| 5012 check_correct_thread_executing(); | |
| 5013 // world is stopped at this checkpoint | |
| 5014 assert(SafepointSynchronize::is_at_safepoint(), | |
| 5015 "world should be stopped"); | |
|
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|
5016 TraceCMSMemoryManagerStats tms(_collectorState,GenCollectedHeap::heap()->gc_cause()); |
|
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|
5017 |
| 0 | 5018 verify_work_stacks_empty(); |
| 5019 verify_overflow_empty(); | |
| 5020 | |
| 5021 SpecializationStats::clear(); | |
| 5022 if (PrintGCDetails) { | |
| 5023 gclog_or_tty->print("[YG occupancy: "SIZE_FORMAT" K ("SIZE_FORMAT" K)]", | |
| 5024 _young_gen->used() / K, | |
| 5025 _young_gen->capacity() / K); | |
| 5026 } | |
| 5027 if (asynch) { | |
| 5028 if (CMSScavengeBeforeRemark) { | |
| 5029 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 5030 // Temporarily set flag to false, GCH->do_collection will | |
| 5031 // expect it to be false and set to true | |
| 5032 FlagSetting fl(gch->_is_gc_active, false); | |
| 10405 | 5033 NOT_PRODUCT(GCTraceTime t("Scavenge-Before-Remark", |
| 5034 PrintGCDetails && Verbose, true, _gc_timer_cm);) | |
| 0 | 5035 int level = _cmsGen->level() - 1; |
| 5036 if (level >= 0) { | |
| 5037 gch->do_collection(true, // full (i.e. force, see below) | |
| 5038 false, // !clear_all_soft_refs | |
| 5039 0, // size | |
| 5040 false, // is_tlab | |
| 5041 level // max_level | |
| 5042 ); | |
| 5043 } | |
| 5044 } | |
| 5045 FreelistLocker x(this); | |
| 5046 MutexLockerEx y(bitMapLock(), | |
| 5047 Mutex::_no_safepoint_check_flag); | |
| 5048 assert(!init_mark_was_synchronous, "but that's impossible!"); | |
| 5049 checkpointRootsFinalWork(asynch, clear_all_soft_refs, false); | |
| 5050 } else { | |
| 5051 // already have all the locks | |
| 5052 checkpointRootsFinalWork(asynch, clear_all_soft_refs, | |
| 5053 init_mark_was_synchronous); | |
| 5054 } | |
| 5055 verify_work_stacks_empty(); | |
| 5056 verify_overflow_empty(); | |
| 5057 SpecializationStats::print(); | |
| 5058 } | |
| 5059 | |
| 5060 void CMSCollector::checkpointRootsFinalWork(bool asynch, | |
| 5061 bool clear_all_soft_refs, bool init_mark_was_synchronous) { | |
| 5062 | |
| 10405 | 5063 NOT_PRODUCT(GCTraceTime tr("checkpointRootsFinalWork", PrintGCDetails, false, _gc_timer_cm);) |
| 0 | 5064 |
| 5065 assert(haveFreelistLocks(), "must have free list locks"); | |
| 5066 assert_lock_strong(bitMapLock()); | |
| 5067 | |
| 5068 if (UseAdaptiveSizePolicy) { | |
| 5069 size_policy()->checkpoint_roots_final_begin(); | |
| 5070 } | |
| 5071 | |
| 5072 ResourceMark rm; | |
| 5073 HandleMark hm; | |
| 5074 | |
| 5075 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 5076 | |
|
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|
5077 if (should_unload_classes()) { |
| 0 | 5078 CodeCache::gc_prologue(); |
| 5079 } | |
| 5080 assert(haveFreelistLocks(), "must have free list locks"); | |
| 5081 assert_lock_strong(bitMapLock()); | |
| 5082 | |
| 5083 if (!init_mark_was_synchronous) { | |
| 5084 // We might assume that we need not fill TLAB's when | |
| 5085 // CMSScavengeBeforeRemark is set, because we may have just done | |
| 5086 // a scavenge which would have filled all TLAB's -- and besides | |
| 5087 // Eden would be empty. This however may not always be the case -- | |
| 5088 // for instance although we asked for a scavenge, it may not have | |
| 5089 // happened because of a JNI critical section. We probably need | |
| 5090 // a policy for deciding whether we can in that case wait until | |
| 5091 // the critical section releases and then do the remark following | |
| 5092 // the scavenge, and skip it here. In the absence of that policy, | |
| 5093 // or of an indication of whether the scavenge did indeed occur, | |
| 5094 // we cannot rely on TLAB's having been filled and must do | |
| 5095 // so here just in case a scavenge did not happen. | |
| 5096 gch->ensure_parsability(false); // fill TLAB's, but no need to retire them | |
| 5097 // Update the saved marks which may affect the root scans. | |
| 5098 gch->save_marks(); | |
| 5099 | |
|
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|
5100 if (CMSPrintEdenSurvivorChunks) { |
|
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|
5101 print_eden_and_survivor_chunk_arrays(); |
|
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5102 } |
|
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|
5103 |
| 0 | 5104 { |
| 5105 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact;) | |
| 5106 | |
| 5107 // Note on the role of the mod union table: | |
| 5108 // Since the marker in "markFromRoots" marks concurrently with | |
| 5109 // mutators, it is possible for some reachable objects not to have been | |
| 5110 // scanned. For instance, an only reference to an object A was | |
| 5111 // placed in object B after the marker scanned B. Unless B is rescanned, | |
| 5112 // A would be collected. Such updates to references in marked objects | |
| 5113 // are detected via the mod union table which is the set of all cards | |
| 5114 // dirtied since the first checkpoint in this GC cycle and prior to | |
| 5115 // the most recent young generation GC, minus those cleaned up by the | |
| 5116 // concurrent precleaning. | |
|
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|
5117 if (CMSParallelRemarkEnabled && CollectedHeap::use_parallel_gc_threads()) { |
| 10405 | 5118 GCTraceTime t("Rescan (parallel) ", PrintGCDetails, false, _gc_timer_cm); |
| 0 | 5119 do_remark_parallel(); |
| 5120 } else { | |
| 10405 | 5121 GCTraceTime t("Rescan (non-parallel) ", PrintGCDetails, false, |
| 5122 _gc_timer_cm); | |
| 0 | 5123 do_remark_non_parallel(); |
| 5124 } | |
| 5125 } | |
| 5126 } else { | |
| 5127 assert(!asynch, "Can't have init_mark_was_synchronous in asynch mode"); | |
| 5128 // The initial mark was stop-world, so there's no rescanning to | |
| 5129 // do; go straight on to the next step below. | |
| 5130 } | |
| 5131 verify_work_stacks_empty(); | |
| 5132 verify_overflow_empty(); | |
| 5133 | |
| 5134 { | |
| 10405 | 5135 NOT_PRODUCT(GCTraceTime ts("refProcessingWork", PrintGCDetails, false, _gc_timer_cm);) |
| 0 | 5136 refProcessingWork(asynch, clear_all_soft_refs); |
| 5137 } | |
| 5138 verify_work_stacks_empty(); | |
| 5139 verify_overflow_empty(); | |
| 5140 | |
|
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|
5141 if (should_unload_classes()) { |
| 0 | 5142 CodeCache::gc_epilogue(); |
| 5143 } | |
|
2147
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|
5144 JvmtiExport::gc_epilogue(); |
| 0 | 5145 |
| 5146 // If we encountered any (marking stack / work queue) overflow | |
| 5147 // events during the current CMS cycle, take appropriate | |
| 5148 // remedial measures, where possible, so as to try and avoid | |
| 5149 // recurrence of that condition. | |
| 5150 assert(_markStack.isEmpty(), "No grey objects"); | |
| 5151 size_t ser_ovflw = _ser_pmc_remark_ovflw + _ser_pmc_preclean_ovflw + | |
|
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|
5152 _ser_kac_ovflw + _ser_kac_preclean_ovflw; |
| 0 | 5153 if (ser_ovflw > 0) { |
| 5154 if (PrintCMSStatistics != 0) { | |
| 5155 gclog_or_tty->print_cr("Marking stack overflow (benign) " | |
|
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|
5156 "(pmc_pc="SIZE_FORMAT", pmc_rm="SIZE_FORMAT", kac="SIZE_FORMAT |
|
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|
5157 ", kac_preclean="SIZE_FORMAT")", |
| 0 | 5158 _ser_pmc_preclean_ovflw, _ser_pmc_remark_ovflw, |
|
452
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|
5159 _ser_kac_ovflw, _ser_kac_preclean_ovflw); |
| 0 | 5160 } |
| 5161 _markStack.expand(); | |
| 5162 _ser_pmc_remark_ovflw = 0; | |
| 5163 _ser_pmc_preclean_ovflw = 0; | |
|
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|
5164 _ser_kac_preclean_ovflw = 0; |
| 0 | 5165 _ser_kac_ovflw = 0; |
| 5166 } | |
| 5167 if (_par_pmc_remark_ovflw > 0 || _par_kac_ovflw > 0) { | |
| 5168 if (PrintCMSStatistics != 0) { | |
| 5169 gclog_or_tty->print_cr("Work queue overflow (benign) " | |
| 5170 "(pmc_rm="SIZE_FORMAT", kac="SIZE_FORMAT")", | |
| 5171 _par_pmc_remark_ovflw, _par_kac_ovflw); | |
| 5172 } | |
| 5173 _par_pmc_remark_ovflw = 0; | |
| 5174 _par_kac_ovflw = 0; | |
| 5175 } | |
| 5176 if (PrintCMSStatistics != 0) { | |
| 5177 if (_markStack._hit_limit > 0) { | |
| 5178 gclog_or_tty->print_cr(" (benign) Hit max stack size limit ("SIZE_FORMAT")", | |
| 5179 _markStack._hit_limit); | |
| 5180 } | |
| 5181 if (_markStack._failed_double > 0) { | |
| 5182 gclog_or_tty->print_cr(" (benign) Failed stack doubling ("SIZE_FORMAT")," | |
| 5183 " current capacity "SIZE_FORMAT, | |
| 5184 _markStack._failed_double, | |
| 5185 _markStack.capacity()); | |
| 5186 } | |
| 5187 } | |
| 5188 _markStack._hit_limit = 0; | |
| 5189 _markStack._failed_double = 0; | |
| 5190 | |
| 5191 if ((VerifyAfterGC || VerifyDuringGC) && | |
| 5192 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
| 5193 verify_after_remark(); | |
| 5194 } | |
| 5195 | |
| 10405 | 5196 _gc_tracer_cm->report_object_count_after_gc(&_is_alive_closure); |
| 5197 | |
| 0 | 5198 // Change under the freelistLocks. |
| 5199 _collectorState = Sweeping; | |
| 5200 // Call isAllClear() under bitMapLock | |
|
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5201 assert(_modUnionTable.isAllClear(), |
|
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|
5202 "Should be clear by end of the final marking"); |
|
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|
5203 assert(_ct->klass_rem_set()->mod_union_is_clear(), |
|
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|
5204 "Should be clear by end of the final marking"); |
| 0 | 5205 if (UseAdaptiveSizePolicy) { |
| 5206 size_policy()->checkpoint_roots_final_end(gch->gc_cause()); | |
| 5207 } | |
| 5208 } | |
| 5209 | |
| 11975 | 5210 void CMSParInitialMarkTask::work(uint worker_id) { |
| 5211 elapsedTimer _timer; | |
| 5212 ResourceMark rm; | |
| 5213 HandleMark hm; | |
| 5214 | |
| 5215 // ---------- scan from roots -------------- | |
| 5216 _timer.start(); | |
| 5217 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 5218 Par_MarkRefsIntoClosure par_mri_cl(_collector->_span, &(_collector->_markBitMap)); | |
| 5219 CMKlassClosure klass_closure(&par_mri_cl); | |
| 5220 | |
| 5221 // ---------- young gen roots -------------- | |
| 5222 { | |
| 5223 work_on_young_gen_roots(worker_id, &par_mri_cl); | |
| 5224 _timer.stop(); | |
| 5225 if (PrintCMSStatistics != 0) { | |
| 5226 gclog_or_tty->print_cr( | |
| 5227 "Finished young gen initial mark scan work in %dth thread: %3.3f sec", | |
| 5228 worker_id, _timer.seconds()); | |
| 5229 } | |
| 5230 } | |
| 5231 | |
| 5232 // ---------- remaining roots -------------- | |
| 5233 _timer.reset(); | |
| 5234 _timer.start(); | |
| 5235 gch->gen_process_strong_roots(_collector->_cmsGen->level(), | |
| 5236 false, // yg was scanned above | |
| 5237 false, // this is parallel code | |
| 5238 SharedHeap::ScanningOption(_collector->CMSCollector::roots_scanning_options()), | |
| 5239 &par_mri_cl, | |
|
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|
5240 true, // walk all of code cache if (so & SO_AllCodeCache) |
| 11975 | 5241 NULL, |
| 5242 &klass_closure); | |
| 5243 assert(_collector->should_unload_classes() | |
|
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|
5244 || (_collector->CMSCollector::roots_scanning_options() & SharedHeap::SO_AllCodeCache), |
| 11975 | 5245 "if we didn't scan the code cache, we have to be ready to drop nmethods with expired weak oops"); |
| 5246 _timer.stop(); | |
| 5247 if (PrintCMSStatistics != 0) { | |
| 5248 gclog_or_tty->print_cr( | |
| 5249 "Finished remaining root initial mark scan work in %dth thread: %3.3f sec", | |
| 5250 worker_id, _timer.seconds()); | |
| 5251 } | |
| 5252 } | |
| 5253 | |
| 0 | 5254 // Parallel remark task |
| 11975 | 5255 class CMSParRemarkTask: public CMSParMarkTask { |
| 0 | 5256 CompactibleFreeListSpace* _cms_space; |
| 5257 | |
| 5258 // The per-thread work queues, available here for stealing. | |
| 5259 OopTaskQueueSet* _task_queues; | |
| 5260 ParallelTaskTerminator _term; | |
| 5261 | |
| 5262 public: | |
|
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|
5263 // A value of 0 passed to n_workers will cause the number of |
|
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|
5264 // workers to be taken from the active workers in the work gang. |
| 0 | 5265 CMSParRemarkTask(CMSCollector* collector, |
| 5266 CompactibleFreeListSpace* cms_space, | |
|
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|
5267 int n_workers, FlexibleWorkGang* workers, |
| 0 | 5268 OopTaskQueueSet* task_queues): |
| 11975 | 5269 CMSParMarkTask("Rescan roots and grey objects in parallel", |
| 5270 collector, n_workers), | |
|
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|
5271 _cms_space(cms_space), |
| 0 | 5272 _task_queues(task_queues), |
|
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|
5273 _term(n_workers, task_queues) { } |
| 0 | 5274 |
| 5275 OopTaskQueueSet* task_queues() { return _task_queues; } | |
| 5276 | |
| 5277 OopTaskQueue* work_queue(int i) { return task_queues()->queue(i); } | |
| 5278 | |
| 5279 ParallelTaskTerminator* terminator() { return &_term; } | |
|
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|
5280 int n_workers() { return _n_workers; } |
| 0 | 5281 |
|
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|
5282 void work(uint worker_id); |
| 0 | 5283 |
| 5284 private: | |
| 5285 // ... of dirty cards in old space | |
| 5286 void do_dirty_card_rescan_tasks(CompactibleFreeListSpace* sp, int i, | |
| 5287 Par_MarkRefsIntoAndScanClosure* cl); | |
| 5288 | |
| 5289 // ... work stealing for the above | |
| 5290 void do_work_steal(int i, Par_MarkRefsIntoAndScanClosure* cl, int* seed); | |
| 5291 }; | |
| 5292 | |
|
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|
5293 class RemarkKlassClosure : public KlassClosure { |
|
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|
5294 CMKlassClosure _cm_klass_closure; |
|
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5295 public: |
|
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|
5296 RemarkKlassClosure(OopClosure* oop_closure) : _cm_klass_closure(oop_closure) {} |
|
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|
5297 void do_klass(Klass* k) { |
|
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5298 // Check if we have modified any oops in the Klass during the concurrent marking. |
|
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|
5299 if (k->has_accumulated_modified_oops()) { |
|
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|
5300 k->clear_accumulated_modified_oops(); |
|
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5301 |
|
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|
5302 // We could have transfered the current modified marks to the accumulated marks, |
|
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5303 // like we do with the Card Table to Mod Union Table. But it's not really necessary. |
|
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|
5304 } else if (k->has_modified_oops()) { |
|
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changeset
|
5305 // Don't clear anything, this info is needed by the next young collection. |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5306 } else { |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5307 // No modified oops in the Klass. |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5308 return; |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5309 } |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5310 |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5311 // The klass has modified fields, need to scan the klass. |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5312 _cm_klass_closure.do_klass(k); |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5313 } |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5314 }; |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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diff
changeset
|
5315 |
| 11975 | 5316 void CMSParMarkTask::work_on_young_gen_roots(uint worker_id, OopsInGenClosure* cl) { |
| 5317 DefNewGeneration* dng = _collector->_young_gen->as_DefNewGeneration(); | |
| 5318 EdenSpace* eden_space = dng->eden(); | |
| 5319 ContiguousSpace* from_space = dng->from(); | |
| 5320 ContiguousSpace* to_space = dng->to(); | |
| 5321 | |
| 5322 HeapWord** eca = _collector->_eden_chunk_array; | |
| 5323 size_t ect = _collector->_eden_chunk_index; | |
| 5324 HeapWord** sca = _collector->_survivor_chunk_array; | |
| 5325 size_t sct = _collector->_survivor_chunk_index; | |
| 5326 | |
| 5327 assert(ect <= _collector->_eden_chunk_capacity, "out of bounds"); | |
| 5328 assert(sct <= _collector->_survivor_chunk_capacity, "out of bounds"); | |
| 5329 | |
| 5330 do_young_space_rescan(worker_id, cl, to_space, NULL, 0); | |
| 5331 do_young_space_rescan(worker_id, cl, from_space, sca, sct); | |
| 5332 do_young_space_rescan(worker_id, cl, eden_space, eca, ect); | |
| 5333 } | |
| 5334 | |
|
1833
8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
jmasa
parents:
1777
diff
changeset
|
5335 // work_queue(i) is passed to the closure |
|
8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
jmasa
parents:
1777
diff
changeset
|
5336 // Par_MarkRefsIntoAndScanClosure. The "i" parameter |
|
8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
jmasa
parents:
1777
diff
changeset
|
5337 // also is passed to do_dirty_card_rescan_tasks() and to |
|
8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
jmasa
parents:
1777
diff
changeset
|
5338 // do_work_steal() to select the i-th task_queue. |
|
8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
jmasa
parents:
1777
diff
changeset
|
5339 |
|
4728
441e946dc1af
7121618: Change type of number of GC workers to unsigned int.
jmasa
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4128
diff
changeset
|
5340 void CMSParRemarkTask::work(uint worker_id) { |
| 0 | 5341 elapsedTimer _timer; |
| 5342 ResourceMark rm; | |
| 5343 HandleMark hm; | |
| 5344 | |
| 5345 // ---------- rescan from roots -------------- | |
| 5346 _timer.start(); | |
| 5347 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 5348 Par_MarkRefsIntoAndScanClosure par_mrias_cl(_collector, | |
| 5349 _collector->_span, _collector->ref_processor(), | |
| 5350 &(_collector->_markBitMap), | |
|
6725
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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diff
changeset
|
5351 work_queue(worker_id)); |
| 0 | 5352 |
| 5353 // Rescan young gen roots first since these are likely | |
| 5354 // coarsely partitioned and may, on that account, constitute | |
| 5355 // the critical path; thus, it's best to start off that | |
| 5356 // work first. | |
| 5357 // ---------- young gen roots -------------- | |
| 5358 { | |
| 11975 | 5359 work_on_young_gen_roots(worker_id, &par_mrias_cl); |
| 0 | 5360 _timer.stop(); |
| 5361 if (PrintCMSStatistics != 0) { | |
| 5362 gclog_or_tty->print_cr( | |
| 5363 "Finished young gen rescan work in %dth thread: %3.3f sec", | |
|
4728
441e946dc1af
7121618: Change type of number of GC workers to unsigned int.
jmasa
parents:
4128
diff
changeset
|
5364 worker_id, _timer.seconds()); |
| 0 | 5365 } |
| 5366 } | |
| 5367 | |
| 5368 // ---------- remaining roots -------------- | |
| 5369 _timer.reset(); | |
| 5370 _timer.start(); | |
| 5371 gch->gen_process_strong_roots(_collector->_cmsGen->level(), | |
| 5372 false, // yg was scanned above | |
|
989
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
5373 false, // this is parallel code |
| 0 | 5374 SharedHeap::ScanningOption(_collector->CMSCollector::roots_scanning_options()), |
|
989
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
5375 &par_mrias_cl, |
|
14308
870aedf4ba4f
8032379: Remove the is_scavenging flag to process_strong_roots
mgerdin
parents:
13400
diff
changeset
|
5376 true, // walk all of code cache if (so & SO_AllCodeCache) |
|
6725
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5377 NULL, |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
5378 NULL); // The dirty klasses will be handled below |
|
989
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
5379 assert(_collector->should_unload_classes() |
|
14308
870aedf4ba4f
8032379: Remove the is_scavenging flag to process_strong_roots
mgerdin
parents:
13400
diff
changeset
|
5380 || (_collector->CMSCollector::roots_scanning_options() & SharedHeap::SO_AllCodeCache), |
|
989
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
5381 "if we didn't scan the code cache, we have to be ready to drop nmethods with expired weak oops"); |
| 0 | 5382 _timer.stop(); |
| 5383 if (PrintCMSStatistics != 0) { | |
| 5384 gclog_or_tty->print_cr( | |
| 5385 "Finished remaining root rescan work in %dth thread: %3.3f sec", | |
|
4728
441e946dc1af
7121618: Change type of number of GC workers to unsigned int.
jmasa
parents:
4128
diff
changeset
|
5386 worker_id, _timer.seconds()); |
| 0 | 5387 } |
| 5388 | |
|
6725
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5389 // ---------- unhandled CLD scanning ---------- |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5390 if (worker_id == 0) { // Single threaded at the moment. |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5391 _timer.reset(); |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5392 _timer.start(); |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5393 |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5394 // Scan all new class loader data objects and new dependencies that were |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5395 // introduced during concurrent marking. |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5396 ResourceMark rm; |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5397 GrowableArray<ClassLoaderData*>* array = ClassLoaderDataGraph::new_clds(); |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5398 for (int i = 0; i < array->length(); i++) { |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5399 par_mrias_cl.do_class_loader_data(array->at(i)); |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5400 } |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5401 |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5402 // We don't need to keep track of new CLDs anymore. |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5403 ClassLoaderDataGraph::remember_new_clds(false); |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5404 |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5405 _timer.stop(); |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5406 if (PrintCMSStatistics != 0) { |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5407 gclog_or_tty->print_cr( |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5408 "Finished unhandled CLD scanning work in %dth thread: %3.3f sec", |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5409 worker_id, _timer.seconds()); |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5410 } |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5411 } |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5412 |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5413 // ---------- dirty klass scanning ---------- |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5414 if (worker_id == 0) { // Single threaded at the moment. |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5415 _timer.reset(); |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5416 _timer.start(); |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5417 |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5418 // Scan all classes that was dirtied during the concurrent marking phase. |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5419 RemarkKlassClosure remark_klass_closure(&par_mrias_cl); |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5420 ClassLoaderDataGraph::classes_do(&remark_klass_closure); |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5421 |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5422 _timer.stop(); |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5423 if (PrintCMSStatistics != 0) { |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5424 gclog_or_tty->print_cr( |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5425 "Finished dirty klass scanning work in %dth thread: %3.3f sec", |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5426 worker_id, _timer.seconds()); |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5427 } |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5428 } |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5429 |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5430 // We might have added oops to ClassLoaderData::_handles during the |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5431 // concurrent marking phase. These oops point to newly allocated objects |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5432 // that are guaranteed to be kept alive. Either by the direct allocation |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5433 // code, or when the young collector processes the strong roots. Hence, |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5434 // we don't have to revisit the _handles block during the remark phase. |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5435 |
| 0 | 5436 // ---------- rescan dirty cards ------------ |
| 5437 _timer.reset(); | |
| 5438 _timer.start(); | |
| 5439 | |
| 5440 // Do the rescan tasks for each of the two spaces | |
|
6725
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
5441 // (cms_space) in turn. |
|
4728
441e946dc1af
7121618: Change type of number of GC workers to unsigned int.
jmasa
parents:
4128
diff
changeset
|
5442 // "worker_id" is passed to select the task_queue for "worker_id" |
|
441e946dc1af
7121618: Change type of number of GC workers to unsigned int.
jmasa
parents:
4128
diff
changeset
|
5443 do_dirty_card_rescan_tasks(_cms_space, worker_id, &par_mrias_cl); |
| 0 | 5444 _timer.stop(); |
| 5445 if (PrintCMSStatistics != 0) { | |
| 5446 gclog_or_tty->print_cr( | |
| 5447 "Finished dirty card rescan work in %dth thread: %3.3f sec", | |
|
4728
441e946dc1af
7121618: Change type of number of GC workers to unsigned int.
jmasa
parents:
4128
diff
changeset
|
5448 worker_id, _timer.seconds()); |
| 0 | 5449 } |
| 5450 | |
| 5451 // ---------- steal work from other threads ... | |
| 5452 // ---------- ... and drain overflow list. | |
| 5453 _timer.reset(); | |
| 5454 _timer.start(); | |
|
4728
441e946dc1af
7121618: Change type of number of GC workers to unsigned int.
jmasa
parents:
4128
diff
changeset
|
5455 do_work_steal(worker_id, &par_mrias_cl, _collector->hash_seed(worker_id)); |
| 0 | 5456 _timer.stop(); |
| 5457 if (PrintCMSStatistics != 0) { | |
| 5458 gclog_or_tty->print_cr( | |
| 5459 "Finished work stealing in %dth thread: %3.3f sec", | |
|
4728
441e946dc1af
7121618: Change type of number of GC workers to unsigned int.
jmasa
parents:
4128
diff
changeset
|
5460 worker_id, _timer.seconds()); |
| 0 | 5461 } |
| 5462 } | |
| 5463 | |
|
1833
8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
jmasa
parents:
1777
diff
changeset
|
5464 // Note that parameter "i" is not used. |
| 0 | 5465 void |
| 11975 | 5466 CMSParMarkTask::do_young_space_rescan(uint worker_id, |
| 5467 OopsInGenClosure* cl, ContiguousSpace* space, | |
| 0 | 5468 HeapWord** chunk_array, size_t chunk_top) { |
| 5469 // Until all tasks completed: | |
| 5470 // . claim an unclaimed task | |
| 5471 // . compute region boundaries corresponding to task claimed | |
| 5472 // using chunk_array | |
| 5473 // . par_oop_iterate(cl) over that region | |
| 5474 | |
| 5475 ResourceMark rm; | |
| 5476 HandleMark hm; | |
| 5477 | |
| 5478 SequentialSubTasksDone* pst = space->par_seq_tasks(); | |
| 5479 | |
|
4728
441e946dc1af
7121618: Change type of number of GC workers to unsigned int.
jmasa
parents:
4128
diff
changeset
|
5480 uint nth_task = 0; |
|
441e946dc1af
7121618: Change type of number of GC workers to unsigned int.
jmasa
parents:
4128
diff
changeset
|
5481 uint n_tasks = pst->n_tasks(); |
| 0 | 5482 |
|
12088
cb9da55b1990
8021809: Partitioning based on eden sampling during allocation not reset correctly
jmasa
parents:
12029
diff
changeset
|
5483 if (n_tasks > 0) { |
|
cb9da55b1990
8021809: Partitioning based on eden sampling during allocation not reset correctly
jmasa
parents:
12029
diff
changeset
|
5484 assert(pst->valid(), "Uninitialized use?"); |
|
cb9da55b1990
8021809: Partitioning based on eden sampling during allocation not reset correctly
jmasa
parents:
12029
diff
changeset
|
5485 HeapWord *start, *end; |
|
cb9da55b1990
8021809: Partitioning based on eden sampling during allocation not reset correctly
jmasa
parents:
12029
diff
changeset
|
5486 while (!pst->is_task_claimed(/* reference */ nth_task)) { |
|
cb9da55b1990
8021809: Partitioning based on eden sampling during allocation not reset correctly
jmasa
parents:
12029
diff
changeset
|
5487 // We claimed task # nth_task; compute its boundaries. |
|
cb9da55b1990
8021809: Partitioning based on eden sampling during allocation not reset correctly
jmasa
parents:
12029
diff
changeset
|
5488 if (chunk_top == 0) { // no samples were taken |
|
cb9da55b1990
8021809: Partitioning based on eden sampling during allocation not reset correctly
jmasa
parents:
12029
diff
changeset
|
5489 assert(nth_task == 0 && n_tasks == 1, "Can have only 1 EdenSpace task"); |
|
cb9da55b1990
8021809: Partitioning based on eden sampling during allocation not reset correctly
jmasa
parents:
12029
diff
changeset
|
5490 start = space->bottom(); |
|
cb9da55b1990
8021809: Partitioning based on eden sampling during allocation not reset correctly
jmasa
parents:
12029
diff
changeset
|
5491 end = space->top(); |
|
cb9da55b1990
8021809: Partitioning based on eden sampling during allocation not reset correctly
jmasa
parents:
12029
diff
changeset
|
5492 } else if (nth_task == 0) { |
|
cb9da55b1990
8021809: Partitioning based on eden sampling during allocation not reset correctly
jmasa
parents:
12029
diff
changeset
|
5493 start = space->bottom(); |
|
cb9da55b1990
8021809: Partitioning based on eden sampling during allocation not reset correctly
jmasa
parents:
12029
diff
changeset
|
5494 end = chunk_array[nth_task]; |
|
cb9da55b1990
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|
5495 } else if (nth_task < (uint)chunk_top) { |
|
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5496 assert(nth_task >= 1, "Control point invariant"); |
|
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5497 start = chunk_array[nth_task - 1]; |
|
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|
5498 end = chunk_array[nth_task]; |
|
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|
5499 } else { |
|
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|
5500 assert(nth_task == (uint)chunk_top, "Control point invariant"); |
|
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|
5501 start = chunk_array[chunk_top - 1]; |
|
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|
5502 end = space->top(); |
|
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|
5503 } |
|
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|
5504 MemRegion mr(start, end); |
|
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|
5505 // Verify that mr is in space |
|
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5506 assert(mr.is_empty() || space->used_region().contains(mr), |
|
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|
5507 "Should be in space"); |
|
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|
5508 // Verify that "start" is an object boundary |
|
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5509 assert(mr.is_empty() || oop(mr.start())->is_oop(), |
|
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|
5510 "Should be an oop"); |
|
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5511 space->par_oop_iterate(mr, cl); |
|
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|
5512 } |
|
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|
5513 pst->all_tasks_completed(); |
|
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|
5514 } |
| 0 | 5515 } |
| 5516 | |
| 5517 void | |
| 5518 CMSParRemarkTask::do_dirty_card_rescan_tasks( | |
| 5519 CompactibleFreeListSpace* sp, int i, | |
| 5520 Par_MarkRefsIntoAndScanClosure* cl) { | |
| 5521 // Until all tasks completed: | |
| 5522 // . claim an unclaimed task | |
| 5523 // . compute region boundaries corresponding to task claimed | |
| 5524 // . transfer dirty bits ct->mut for that region | |
| 5525 // . apply rescanclosure to dirty mut bits for that region | |
| 5526 | |
| 5527 ResourceMark rm; | |
| 5528 HandleMark hm; | |
| 5529 | |
| 5530 OopTaskQueue* work_q = work_queue(i); | |
| 5531 ModUnionClosure modUnionClosure(&(_collector->_modUnionTable)); | |
| 5532 // CAUTION! CAUTION! CAUTION! CAUTION! CAUTION! CAUTION! CAUTION! | |
| 5533 // CAUTION: This closure has state that persists across calls to | |
| 5534 // the work method dirty_range_iterate_clear() in that it has | |
| 14309 | 5535 // embedded in it a (subtype of) UpwardsObjectClosure. The |
| 5536 // use of that state in the embedded UpwardsObjectClosure instance | |
| 0 | 5537 // assumes that the cards are always iterated (even if in parallel |
| 5538 // by several threads) in monotonically increasing order per each | |
| 5539 // thread. This is true of the implementation below which picks | |
| 5540 // card ranges (chunks) in monotonically increasing order globally | |
| 5541 // and, a-fortiori, in monotonically increasing order per thread | |
| 5542 // (the latter order being a subsequence of the former). | |
| 5543 // If the work code below is ever reorganized into a more chaotic | |
| 5544 // work-partitioning form than the current "sequential tasks" | |
| 5545 // paradigm, the use of that persistent state will have to be | |
| 5546 // revisited and modified appropriately. See also related | |
| 5547 // bug 4756801 work on which should examine this code to make | |
| 5548 // sure that the changes there do not run counter to the | |
| 5549 // assumptions made here and necessary for correctness and | |
| 5550 // efficiency. Note also that this code might yield inefficient | |
| 14309 | 5551 // behavior in the case of very large objects that span one or |
| 0 | 5552 // more work chunks. Such objects would potentially be scanned |
| 5553 // several times redundantly. Work on 4756801 should try and | |
| 5554 // address that performance anomaly if at all possible. XXX | |
| 5555 MemRegion full_span = _collector->_span; | |
| 5556 CMSBitMap* bm = &(_collector->_markBitMap); // shared | |
| 5557 MarkFromDirtyCardsClosure | |
| 5558 greyRescanClosure(_collector, full_span, // entire span of interest | |
|
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5559 sp, bm, work_q, cl); |
| 0 | 5560 |
| 5561 SequentialSubTasksDone* pst = sp->conc_par_seq_tasks(); | |
| 5562 assert(pst->valid(), "Uninitialized use?"); | |
|
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|
5563 uint nth_task = 0; |
| 0 | 5564 const int alignment = CardTableModRefBS::card_size * BitsPerWord; |
| 5565 MemRegion span = sp->used_region(); | |
| 5566 HeapWord* start_addr = span.start(); | |
| 5567 HeapWord* end_addr = (HeapWord*)round_to((intptr_t)span.end(), | |
| 5568 alignment); | |
| 5569 const size_t chunk_size = sp->rescan_task_size(); // in HeapWord units | |
| 5570 assert((HeapWord*)round_to((intptr_t)start_addr, alignment) == | |
| 5571 start_addr, "Check alignment"); | |
| 5572 assert((size_t)round_to((intptr_t)chunk_size, alignment) == | |
| 5573 chunk_size, "Check alignment"); | |
| 5574 | |
| 5575 while (!pst->is_task_claimed(/* reference */ nth_task)) { | |
| 5576 // Having claimed the nth_task, compute corresponding mem-region, | |
| 14309 | 5577 // which is a-fortiori aligned correctly (i.e. at a MUT boundary). |
| 0 | 5578 // The alignment restriction ensures that we do not need any |
| 5579 // synchronization with other gang-workers while setting or | |
| 5580 // clearing bits in thus chunk of the MUT. | |
| 5581 MemRegion this_span = MemRegion(start_addr + nth_task*chunk_size, | |
| 5582 start_addr + (nth_task+1)*chunk_size); | |
| 5583 // The last chunk's end might be way beyond end of the | |
| 5584 // used region. In that case pull back appropriately. | |
| 5585 if (this_span.end() > end_addr) { | |
| 5586 this_span.set_end(end_addr); | |
| 5587 assert(!this_span.is_empty(), "Program logic (calculation of n_tasks)"); | |
| 5588 } | |
| 5589 // Iterate over the dirty cards covering this chunk, marking them | |
| 5590 // precleaned, and setting the corresponding bits in the mod union | |
| 5591 // table. Since we have been careful to partition at Card and MUT-word | |
| 5592 // boundaries no synchronization is needed between parallel threads. | |
| 5593 _collector->_ct->ct_bs()->dirty_card_iterate(this_span, | |
| 5594 &modUnionClosure); | |
| 5595 | |
| 5596 // Having transferred these marks into the modUnionTable, | |
| 5597 // rescan the marked objects on the dirty cards in the modUnionTable. | |
| 5598 // Even if this is at a synchronous collection, the initial marking | |
| 5599 // may have been done during an asynchronous collection so there | |
| 5600 // may be dirty bits in the mod-union table. | |
| 5601 _collector->_modUnionTable.dirty_range_iterate_clear( | |
| 5602 this_span, &greyRescanClosure); | |
| 5603 _collector->_modUnionTable.verifyNoOneBitsInRange( | |
| 5604 this_span.start(), | |
| 5605 this_span.end()); | |
| 5606 } | |
| 5607 pst->all_tasks_completed(); // declare that i am done | |
| 5608 } | |
| 5609 | |
| 5610 // . see if we can share work_queues with ParNew? XXX | |
| 5611 void | |
| 5612 CMSParRemarkTask::do_work_steal(int i, Par_MarkRefsIntoAndScanClosure* cl, | |
| 5613 int* seed) { | |
| 5614 OopTaskQueue* work_q = work_queue(i); | |
| 5615 NOT_PRODUCT(int num_steals = 0;) | |
| 5616 oop obj_to_scan; | |
| 5617 CMSBitMap* bm = &(_collector->_markBitMap); | |
| 5618 | |
| 5619 while (true) { | |
| 5620 // Completely finish any left over work from (an) earlier round(s) | |
| 5621 cl->trim_queue(0); | |
|
679
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|
5622 size_t num_from_overflow_list = MIN2((size_t)(work_q->max_elems() - work_q->size())/4, |
|
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|
5623 (size_t)ParGCDesiredObjsFromOverflowList); |
| 0 | 5624 // Now check if there's any work in the overflow list |
|
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|
5625 // Passing ParallelGCThreads as the third parameter, no_of_gc_threads, |
|
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|
5626 // only affects the number of attempts made to get work from the |
|
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|
5627 // overflow list and does not affect the number of workers. Just |
|
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|
5628 // pass ParallelGCThreads so this behavior is unchanged. |
| 0 | 5629 if (_collector->par_take_from_overflow_list(num_from_overflow_list, |
|
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|
5630 work_q, |
|
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|
5631 ParallelGCThreads)) { |
| 0 | 5632 // found something in global overflow list; |
| 5633 // not yet ready to go stealing work from others. | |
| 5634 // We'd like to assert(work_q->size() != 0, ...) | |
| 5635 // because we just took work from the overflow list, | |
| 5636 // but of course we can't since all of that could have | |
| 5637 // been already stolen from us. | |
| 5638 // "He giveth and He taketh away." | |
| 5639 continue; | |
| 5640 } | |
| 5641 // Verify that we have no work before we resort to stealing | |
| 5642 assert(work_q->size() == 0, "Have work, shouldn't steal"); | |
| 5643 // Try to steal from other queues that have work | |
| 5644 if (task_queues()->steal(i, seed, /* reference */ obj_to_scan)) { | |
| 5645 NOT_PRODUCT(num_steals++;) | |
| 5646 assert(obj_to_scan->is_oop(), "Oops, not an oop!"); | |
| 5647 assert(bm->isMarked((HeapWord*)obj_to_scan), "Stole an unmarked oop?"); | |
| 5648 // Do scanning work | |
| 5649 obj_to_scan->oop_iterate(cl); | |
| 5650 // Loop around, finish this work, and try to steal some more | |
| 5651 } else if (terminator()->offer_termination()) { | |
| 5652 break; // nirvana from the infinite cycle | |
| 5653 } | |
| 5654 } | |
| 5655 NOT_PRODUCT( | |
| 5656 if (PrintCMSStatistics != 0) { | |
| 5657 gclog_or_tty->print("\n\t(%d: stole %d oops)", i, num_steals); | |
| 5658 } | |
| 5659 ) | |
| 5660 assert(work_q->size() == 0 && _collector->overflow_list_is_empty(), | |
| 5661 "Else our work is not yet done"); | |
| 5662 } | |
| 5663 | |
|
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|
5664 // Record object boundaries in _eden_chunk_array by sampling the eden |
|
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|
5665 // top in the slow-path eden object allocation code path and record |
|
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|
5666 // the boundaries, if CMSEdenChunksRecordAlways is true. If |
|
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|
5667 // CMSEdenChunksRecordAlways is false, we use the other asynchronous |
|
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|
5668 // sampling in sample_eden() that activates during the part of the |
|
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|
5669 // preclean phase. |
|
7b06ae405d7b
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|
5670 void CMSCollector::sample_eden_chunk() { |
|
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|
5671 if (CMSEdenChunksRecordAlways && _eden_chunk_array != NULL) { |
|
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|
5672 if (_eden_chunk_lock->try_lock()) { |
|
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|
5673 // Record a sample. This is the critical section. The contents |
|
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|
5674 // of the _eden_chunk_array have to be non-decreasing in the |
|
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|
5675 // address order. |
|
7b06ae405d7b
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diff
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|
5676 _eden_chunk_array[_eden_chunk_index] = *_top_addr; |
|
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|
5677 assert(_eden_chunk_array[_eden_chunk_index] <= *_end_addr, |
|
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|
5678 "Unexpected state of Eden"); |
|
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|
5679 if (_eden_chunk_index == 0 || |
|
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|
5680 ((_eden_chunk_array[_eden_chunk_index] > _eden_chunk_array[_eden_chunk_index-1]) && |
|
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|
5681 (pointer_delta(_eden_chunk_array[_eden_chunk_index], |
|
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|
5682 _eden_chunk_array[_eden_chunk_index-1]) >= CMSSamplingGrain))) { |
|
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|
5683 _eden_chunk_index++; // commit sample |
|
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|
5684 } |
|
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|
5685 _eden_chunk_lock->unlock(); |
|
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|
5686 } |
|
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|
5687 } |
|
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|
5688 } |
|
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|
5689 |
| 0 | 5690 // Return a thread-local PLAB recording array, as appropriate. |
| 5691 void* CMSCollector::get_data_recorder(int thr_num) { | |
| 5692 if (_survivor_plab_array != NULL && | |
| 5693 (CMSPLABRecordAlways || | |
| 5694 (_collectorState > Marking && _collectorState < FinalMarking))) { | |
| 5695 assert(thr_num < (int)ParallelGCThreads, "thr_num is out of bounds"); | |
| 5696 ChunkArray* ca = &_survivor_plab_array[thr_num]; | |
| 5697 ca->reset(); // clear it so that fresh data is recorded | |
| 5698 return (void*) ca; | |
| 5699 } else { | |
| 5700 return NULL; | |
| 5701 } | |
| 5702 } | |
| 5703 | |
| 5704 // Reset all the thread-local PLAB recording arrays | |
| 5705 void CMSCollector::reset_survivor_plab_arrays() { | |
| 5706 for (uint i = 0; i < ParallelGCThreads; i++) { | |
| 5707 _survivor_plab_array[i].reset(); | |
| 5708 } | |
| 5709 } | |
| 5710 | |
| 5711 // Merge the per-thread plab arrays into the global survivor chunk | |
| 5712 // array which will provide the partitioning of the survivor space | |
| 11975 | 5713 // for CMS initial scan and rescan. |
|
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|
5714 void CMSCollector::merge_survivor_plab_arrays(ContiguousSpace* surv, |
|
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|
5715 int no_of_gc_threads) { |
| 0 | 5716 assert(_survivor_plab_array != NULL, "Error"); |
| 5717 assert(_survivor_chunk_array != NULL, "Error"); | |
| 11975 | 5718 assert(_collectorState == FinalMarking || |
| 5719 (CMSParallelInitialMarkEnabled && _collectorState == InitialMarking), "Error"); | |
|
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|
5720 for (int j = 0; j < no_of_gc_threads; j++) { |
| 0 | 5721 _cursor[j] = 0; |
| 5722 } | |
| 5723 HeapWord* top = surv->top(); | |
| 5724 size_t i; | |
| 5725 for (i = 0; i < _survivor_chunk_capacity; i++) { // all sca entries | |
| 5726 HeapWord* min_val = top; // Higher than any PLAB address | |
| 5727 uint min_tid = 0; // position of min_val this round | |
|
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|
5728 for (int j = 0; j < no_of_gc_threads; j++) { |
| 0 | 5729 ChunkArray* cur_sca = &_survivor_plab_array[j]; |
| 5730 if (_cursor[j] == cur_sca->end()) { | |
| 5731 continue; | |
| 5732 } | |
| 5733 assert(_cursor[j] < cur_sca->end(), "ctl pt invariant"); | |
| 5734 HeapWord* cur_val = cur_sca->nth(_cursor[j]); | |
| 5735 assert(surv->used_region().contains(cur_val), "Out of bounds value"); | |
| 5736 if (cur_val < min_val) { | |
| 5737 min_tid = j; | |
| 5738 min_val = cur_val; | |
| 5739 } else { | |
| 5740 assert(cur_val < top, "All recorded addresses should be less"); | |
| 5741 } | |
| 5742 } | |
| 5743 // At this point min_val and min_tid are respectively | |
| 5744 // the least address in _survivor_plab_array[j]->nth(_cursor[j]) | |
| 5745 // and the thread (j) that witnesses that address. | |
| 5746 // We record this address in the _survivor_chunk_array[i] | |
| 5747 // and increment _cursor[min_tid] prior to the next round i. | |
| 5748 if (min_val == top) { | |
| 5749 break; | |
| 5750 } | |
| 5751 _survivor_chunk_array[i] = min_val; | |
| 5752 _cursor[min_tid]++; | |
| 5753 } | |
| 5754 // We are all done; record the size of the _survivor_chunk_array | |
| 5755 _survivor_chunk_index = i; // exclusive: [0, i) | |
| 5756 if (PrintCMSStatistics > 0) { | |
| 5757 gclog_or_tty->print(" (Survivor:" SIZE_FORMAT "chunks) ", i); | |
| 5758 } | |
| 5759 // Verify that we used up all the recorded entries | |
| 5760 #ifdef ASSERT | |
| 5761 size_t total = 0; | |
|
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diff
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|
5762 for (int j = 0; j < no_of_gc_threads; j++) { |
| 0 | 5763 assert(_cursor[j] == _survivor_plab_array[j].end(), "Ctl pt invariant"); |
| 5764 total += _cursor[j]; | |
| 5765 } | |
| 5766 assert(total == _survivor_chunk_index, "Ctl Pt Invariant"); | |
| 5767 // Check that the merged array is in sorted order | |
| 5768 if (total > 0) { | |
| 5769 for (size_t i = 0; i < total - 1; i++) { | |
| 5770 if (PrintCMSStatistics > 0) { | |
| 5771 gclog_or_tty->print(" (chunk" SIZE_FORMAT ":" INTPTR_FORMAT ") ", | |
| 5772 i, _survivor_chunk_array[i]); | |
| 5773 } | |
| 5774 assert(_survivor_chunk_array[i] < _survivor_chunk_array[i+1], | |
| 5775 "Not sorted"); | |
| 5776 } | |
| 5777 } | |
| 5778 #endif // ASSERT | |
| 5779 } | |
| 5780 | |
| 5781 // Set up the space's par_seq_tasks structure for work claiming | |
| 11975 | 5782 // for parallel initial scan and rescan of young gen. |
| 0 | 5783 // See ParRescanTask where this is currently used. |
| 5784 void | |
| 5785 CMSCollector:: | |
| 5786 initialize_sequential_subtasks_for_young_gen_rescan(int n_threads) { | |
| 5787 assert(n_threads > 0, "Unexpected n_threads argument"); | |
| 5788 DefNewGeneration* dng = (DefNewGeneration*)_young_gen; | |
| 5789 | |
| 5790 // Eden space | |
|
12088
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8021809: Partitioning based on eden sampling during allocation not reset correctly
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12029
diff
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|
5791 if (!dng->eden()->is_empty()) { |
| 0 | 5792 SequentialSubTasksDone* pst = dng->eden()->par_seq_tasks(); |
| 5793 assert(!pst->valid(), "Clobbering existing data?"); | |
| 5794 // Each valid entry in [0, _eden_chunk_index) represents a task. | |
| 5795 size_t n_tasks = _eden_chunk_index + 1; | |
| 5796 assert(n_tasks == 1 || _eden_chunk_array != NULL, "Error"); | |
|
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|
5797 // Sets the condition for completion of the subtask (how many threads |
|
8b10f48633dc
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|
5798 // need to finish in order to be done). |
|
8b10f48633dc
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|
5799 pst->set_n_threads(n_threads); |
| 0 | 5800 pst->set_n_tasks((int)n_tasks); |
| 5801 } | |
| 5802 | |
| 5803 // Merge the survivor plab arrays into _survivor_chunk_array | |
| 5804 if (_survivor_plab_array != NULL) { | |
|
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jmasa
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diff
changeset
|
5805 merge_survivor_plab_arrays(dng->from(), n_threads); |
| 0 | 5806 } else { |
| 5807 assert(_survivor_chunk_index == 0, "Error"); | |
| 5808 } | |
| 5809 | |
| 5810 // To space | |
| 5811 { | |
| 5812 SequentialSubTasksDone* pst = dng->to()->par_seq_tasks(); | |
| 5813 assert(!pst->valid(), "Clobbering existing data?"); | |
|
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|
5814 // Sets the condition for completion of the subtask (how many threads |
|
8b10f48633dc
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diff
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|
5815 // need to finish in order to be done). |
|
8b10f48633dc
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|
5816 pst->set_n_threads(n_threads); |
| 0 | 5817 pst->set_n_tasks(1); |
| 5818 assert(pst->valid(), "Error"); | |
| 5819 } | |
| 5820 | |
| 5821 // From space | |
| 5822 { | |
| 5823 SequentialSubTasksDone* pst = dng->from()->par_seq_tasks(); | |
| 5824 assert(!pst->valid(), "Clobbering existing data?"); | |
| 5825 size_t n_tasks = _survivor_chunk_index + 1; | |
| 5826 assert(n_tasks == 1 || _survivor_chunk_array != NULL, "Error"); | |
|
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|
5827 // Sets the condition for completion of the subtask (how many threads |
|
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diff
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|
5828 // need to finish in order to be done). |
|
8b10f48633dc
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1777
diff
changeset
|
5829 pst->set_n_threads(n_threads); |
| 0 | 5830 pst->set_n_tasks((int)n_tasks); |
| 5831 assert(pst->valid(), "Error"); | |
| 5832 } | |
| 5833 } | |
| 5834 | |
| 5835 // Parallel version of remark | |
| 5836 void CMSCollector::do_remark_parallel() { | |
| 5837 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
|
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diff
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|
5838 FlexibleWorkGang* workers = gch->workers(); |
| 0 | 5839 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
|
5840 // Choose to use the number of GC workers most recently set |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
parents:
3979
diff
changeset
|
5841 // into "active_workers". If active_workers is not set, set it |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
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3979
diff
changeset
|
5842 // to ParallelGCThreads. |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
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3979
diff
changeset
|
5843 int n_workers = workers->active_workers(); |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
parents:
3979
diff
changeset
|
5844 if (n_workers == 0) { |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
parents:
3979
diff
changeset
|
5845 assert(n_workers > 0, "Should have been set during scavenge"); |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
parents:
3979
diff
changeset
|
5846 n_workers = ParallelGCThreads; |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
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3979
diff
changeset
|
5847 workers->set_active_workers(n_workers); |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
parents:
3979
diff
changeset
|
5848 } |
| 0 | 5849 CompactibleFreeListSpace* cms_space = _cmsGen->cmsSpace(); |
| 5850 | |
| 5851 CMSParRemarkTask tsk(this, | |
|
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diff
changeset
|
5852 cms_space, |
| 0 | 5853 n_workers, workers, task_queues()); |
| 5854 | |
| 5855 // Set up for parallel process_strong_roots work. | |
| 5856 gch->set_par_threads(n_workers); | |
| 5857 // We won't be iterating over the cards in the card table updating | |
| 5858 // the younger_gen cards, so we shouldn't call the following else | |
| 5859 // the verification code as well as subsequent younger_refs_iterate | |
| 5860 // code would get confused. XXX | |
| 5861 // gch->rem_set()->prepare_for_younger_refs_iterate(true); // parallel | |
| 5862 | |
| 5863 // The young gen rescan work will not be done as part of | |
| 5864 // process_strong_roots (which currently doesn't knw how to | |
| 5865 // parallelize such a scan), but rather will be broken up into | |
| 5866 // a set of parallel tasks (via the sampling that the [abortable] | |
| 5867 // preclean phase did of EdenSpace, plus the [two] tasks of | |
| 5868 // scanning the [two] survivor spaces. Further fine-grain | |
| 5869 // parallelization of the scanning of the survivor spaces | |
| 5870 // themselves, and of precleaning of the younger gen itself | |
| 5871 // is deferred to the future. | |
| 5872 initialize_sequential_subtasks_for_young_gen_rescan(n_workers); | |
| 5873 | |
| 5874 // The dirty card rescan work is broken up into a "sequence" | |
| 5875 // of parallel tasks (per constituent space) that are dynamically | |
| 5876 // claimed by the parallel threads. | |
| 5877 cms_space->initialize_sequential_subtasks_for_rescan(n_workers); | |
| 5878 | |
| 5879 // It turns out that even when we're using 1 thread, doing the work in a | |
| 5880 // separate thread causes wide variance in run times. We can't help this | |
| 5881 // in the multi-threaded case, but we special-case n=1 here to get | |
| 5882 // repeatable measurements of the 1-thread overhead of the parallel code. | |
| 5883 if (n_workers > 1) { | |
|
2369
92da084fefc9
6668573: CMS: reference processing crash if ParallelCMSThreads > ParallelGCThreads
ysr
parents:
2365
diff
changeset
|
5884 // 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
|
5885 // 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
|
5886 // ST marking. |
|
92da084fefc9
6668573: CMS: reference processing crash if ParallelCMSThreads > ParallelGCThreads
ysr
parents:
2365
diff
changeset
|
5887 ReferenceProcessorMTDiscoveryMutator mt(ref_processor(), true); |
|
989
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6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
5888 GenCollectedHeap::StrongRootsScope srs(gch); |
| 0 | 5889 workers->run_task(&tsk); |
| 5890 } else { | |
|
4876
be649fefcdc2
7134655: Crash in reference processing when doing single-threaded remarking
stefank
parents:
4728
diff
changeset
|
5891 ReferenceProcessorMTDiscoveryMutator mt(ref_processor(), false); |
|
989
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
5892 GenCollectedHeap::StrongRootsScope srs(gch); |
| 0 | 5893 tsk.work(0); |
| 5894 } | |
|
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diff
changeset
|
5895 |
| 0 | 5896 gch->set_par_threads(0); // 0 ==> non-parallel. |
| 5897 // restore, single-threaded for now, any preserved marks | |
| 5898 // as a result of work_q overflow | |
| 5899 restore_preserved_marks_if_any(); | |
| 5900 } | |
| 5901 | |
| 5902 // Non-parallel version of remark | |
| 5903 void CMSCollector::do_remark_non_parallel() { | |
| 5904 ResourceMark rm; | |
| 5905 HandleMark hm; | |
| 5906 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
|
4876
be649fefcdc2
7134655: Crash in reference processing when doing single-threaded remarking
stefank
parents:
4728
diff
changeset
|
5907 ReferenceProcessorMTDiscoveryMutator mt(ref_processor(), false); |
|
be649fefcdc2
7134655: Crash in reference processing when doing single-threaded remarking
stefank
parents:
4728
diff
changeset
|
5908 |
| 0 | 5909 MarkRefsIntoAndScanClosure |
|
6725
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
5910 mrias_cl(_span, ref_processor(), &_markBitMap, NULL /* not precleaning */, |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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diff
changeset
|
5911 &_markStack, this, |
| 0 | 5912 false /* should_yield */, false /* not precleaning */); |
| 5913 MarkFromDirtyCardsClosure | |
| 5914 markFromDirtyCardsClosure(this, _span, | |
| 5915 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
|
5916 &_markBitMap, &_markStack, &mrias_cl); |
| 0 | 5917 { |
| 10405 | 5918 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
|
5919 // Iterate over the dirty cards, setting the corresponding bits in the |
|
37f87013dfd8
6711316: Open source the Garbage-First garbage collector
ysr
parents:
143
diff
changeset
|
5920 // mod union table. |
| 0 | 5921 { |
| 5922 ModUnionClosure modUnionClosure(&_modUnionTable); | |
| 5923 _ct->ct_bs()->dirty_card_iterate( | |
| 5924 _cmsGen->used_region(), | |
| 5925 &modUnionClosure); | |
| 5926 } | |
| 5927 // Having transferred these marks into the modUnionTable, we just need | |
| 5928 // to rescan the marked objects on the dirty cards in the modUnionTable. | |
| 5929 // The initial marking may have been done during an asynchronous | |
| 5930 // collection so there may be dirty bits in the mod-union table. | |
| 5931 const int alignment = | |
| 5932 CardTableModRefBS::card_size * BitsPerWord; | |
| 5933 { | |
| 5934 // ... First handle dirty cards in CMS gen | |
| 5935 markFromDirtyCardsClosure.set_space(_cmsGen->cmsSpace()); | |
| 5936 MemRegion ur = _cmsGen->used_region(); | |
| 5937 HeapWord* lb = ur.start(); | |
| 5938 HeapWord* ub = (HeapWord*)round_to((intptr_t)ur.end(), alignment); | |
| 5939 MemRegion cms_span(lb, ub); | |
| 5940 _modUnionTable.dirty_range_iterate_clear(cms_span, | |
| 5941 &markFromDirtyCardsClosure); | |
| 5942 verify_work_stacks_empty(); | |
| 5943 if (PrintCMSStatistics != 0) { | |
| 5944 gclog_or_tty->print(" (re-scanned "SIZE_FORMAT" dirty cards in cms gen) ", | |
| 5945 markFromDirtyCardsClosure.num_dirty_cards()); | |
| 5946 } | |
| 5947 } | |
| 5948 } | |
| 5949 if (VerifyDuringGC && | |
| 5950 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
| 5951 HandleMark hm; // Discard invalid handles created during verification | |
|
6865
4202510ee0fe
8000831: Heap verification output incorrect/incomplete
johnc
parents:
6787
diff
changeset
|
5952 Universe::verify(); |
| 0 | 5953 } |
| 5954 { | |
| 10405 | 5955 GCTraceTime t("root rescan", PrintGCDetails, false, _gc_timer_cm); |
| 0 | 5956 |
| 5957 verify_work_stacks_empty(); | |
| 5958 | |
| 5959 gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel. | |
|
989
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
5960 GenCollectedHeap::StrongRootsScope srs(gch); |
| 0 | 5961 gch->gen_process_strong_roots(_cmsGen->level(), |
| 5962 true, // younger gens as roots | |
|
989
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
5963 false, // use the local StrongRootsScope |
| 0 | 5964 SharedHeap::ScanningOption(roots_scanning_options()), |
|
989
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
5965 &mrias_cl, |
|
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
5966 true, // walk code active on stacks |
|
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6197
diff
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|
5967 NULL, |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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diff
changeset
|
5968 NULL); // The dirty klasses will be handled below |
|
da91efe96a93
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coleenp
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6197
diff
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|
5969 |
|
989
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
5970 assert(should_unload_classes() |
|
14308
870aedf4ba4f
8032379: Remove the is_scavenging flag to process_strong_roots
mgerdin
parents:
13400
diff
changeset
|
5971 || (roots_scanning_options() & SharedHeap::SO_AllCodeCache), |
|
989
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
5972 "if we didn't scan the code cache, we have to be ready to drop nmethods with expired weak oops"); |
| 0 | 5973 } |
|
6725
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6197
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changeset
|
5974 |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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changeset
|
5975 { |
| 10405 | 5976 GCTraceTime t("visit unhandled CLDs", PrintGCDetails, false, _gc_timer_cm); |
|
6725
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|
5977 |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
5978 verify_work_stacks_empty(); |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
5979 |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
5980 // Scan all class loader data objects that might have been introduced |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
5981 // during concurrent marking. |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
5982 ResourceMark rm; |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
5983 GrowableArray<ClassLoaderData*>* array = ClassLoaderDataGraph::new_clds(); |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
5984 for (int i = 0; i < array->length(); i++) { |
|
da91efe96a93
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coleenp
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6197
diff
changeset
|
5985 mrias_cl.do_class_loader_data(array->at(i)); |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
5986 } |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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6197
diff
changeset
|
5987 |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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6197
diff
changeset
|
5988 // We don't need to keep track of new CLDs anymore. |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
5989 ClassLoaderDataGraph::remember_new_clds(false); |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
5990 |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
5991 verify_work_stacks_empty(); |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
5992 } |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
5993 |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
5994 { |
| 10405 | 5995 GCTraceTime t("dirty klass scan", PrintGCDetails, false, _gc_timer_cm); |
|
6725
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6964458: Reimplement class meta-data storage to use native memory
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6197
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changeset
|
5996 |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
5997 verify_work_stacks_empty(); |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
5998 |
|
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5999 RemarkKlassClosure remark_klass_closure(&mrias_cl); |
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6000 ClassLoaderDataGraph::classes_do(&remark_klass_closure); |
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6001 |
|
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6002 verify_work_stacks_empty(); |
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6003 } |
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|
6004 |
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6005 // We might have added oops to ClassLoaderData::_handles during the |
|
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|
6006 // concurrent marking phase. These oops point to newly allocated objects |
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6007 // that are guaranteed to be kept alive. Either by the direct allocation |
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6008 // code, or when the young collector processes the strong roots. Hence, |
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6009 // we don't have to revisit the _handles block during the remark phase. |
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6010 |
| 0 | 6011 verify_work_stacks_empty(); |
| 6012 // Restore evacuated mark words, if any, used for overflow list links | |
| 6013 if (!CMSOverflowEarlyRestoration) { | |
| 6014 restore_preserved_marks_if_any(); | |
| 6015 } | |
| 6016 verify_overflow_empty(); | |
| 6017 } | |
| 6018 | |
| 6019 //////////////////////////////////////////////////////// | |
| 6020 // Parallel Reference Processing Task Proxy Class | |
| 6021 //////////////////////////////////////////////////////// | |
|
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6022 class CMSRefProcTaskProxy: public AbstractGangTaskWOopQueues { |
| 0 | 6023 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; |
| 6024 CMSCollector* _collector; | |
| 6025 CMSBitMap* _mark_bit_map; | |
|
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6026 const MemRegion _span; |
| 0 | 6027 ProcessTask& _task; |
| 6028 | |
| 6029 public: | |
| 6030 CMSRefProcTaskProxy(ProcessTask& task, | |
| 6031 CMSCollector* collector, | |
| 6032 const MemRegion& span, | |
| 6033 CMSBitMap* mark_bit_map, | |
|
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6034 AbstractWorkGang* workers, |
| 0 | 6035 OopTaskQueueSet* task_queues): |
|
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6036 // XXX Should superclass AGTWOQ also know about AWG since it knows |
|
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6037 // about the task_queues used by the AWG? Then it could initialize |
|
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6038 // the terminator() object. See 6984287. The set_for_termination() |
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6039 // below is a temporary band-aid for the regression in 6984287. |
|
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6040 AbstractGangTaskWOopQueues("Process referents by policy in parallel", |
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6041 task_queues), |
| 0 | 6042 _task(task), |
|
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6043 _collector(collector), _span(span), _mark_bit_map(mark_bit_map) |
|
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6044 { |
|
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|
6045 assert(_collector->_span.equals(_span) && !_span.is_empty(), |
|
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6046 "Inconsistency in _span"); |
|
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|
6047 set_for_termination(workers->active_workers()); |
|
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6048 } |
| 0 | 6049 |
|
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|
6050 OopTaskQueueSet* task_queues() { return queues(); } |
| 0 | 6051 |
| 6052 OopTaskQueue* work_queue(int i) { return task_queues()->queue(i); } | |
| 6053 | |
| 6054 void do_work_steal(int i, | |
| 6055 CMSParDrainMarkingStackClosure* drain, | |
| 6056 CMSParKeepAliveClosure* keep_alive, | |
| 6057 int* seed); | |
| 6058 | |
|
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|
6059 virtual void work(uint worker_id); |
| 0 | 6060 }; |
| 6061 | |
|
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|
6062 void CMSRefProcTaskProxy::work(uint worker_id) { |
|
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|
6063 assert(_collector->_span.equals(_span), "Inconsistency in _span"); |
| 0 | 6064 CMSParKeepAliveClosure par_keep_alive(_collector, _span, |
| 935 | 6065 _mark_bit_map, |
|
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|
6066 work_queue(worker_id)); |
| 0 | 6067 CMSParDrainMarkingStackClosure par_drain_stack(_collector, _span, |
| 935 | 6068 _mark_bit_map, |
|
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|
6069 work_queue(worker_id)); |
|
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6070 CMSIsAliveClosure is_alive_closure(_span, _mark_bit_map); |
|
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|
6071 _task.work(worker_id, is_alive_closure, par_keep_alive, par_drain_stack); |
| 0 | 6072 if (_task.marks_oops_alive()) { |
|
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|
6073 do_work_steal(worker_id, &par_drain_stack, &par_keep_alive, |
|
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|
6074 _collector->hash_seed(worker_id)); |
|
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|
6075 } |
|
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|
6076 assert(work_queue(worker_id)->size() == 0, "work_queue should be empty"); |
| 0 | 6077 assert(_collector->_overflow_list == NULL, "non-empty _overflow_list"); |
| 6078 } | |
| 6079 | |
| 6080 class CMSRefEnqueueTaskProxy: public AbstractGangTask { | |
| 6081 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; | |
| 6082 EnqueueTask& _task; | |
| 6083 | |
| 6084 public: | |
| 6085 CMSRefEnqueueTaskProxy(EnqueueTask& task) | |
| 6086 : AbstractGangTask("Enqueue reference objects in parallel"), | |
| 6087 _task(task) | |
| 6088 { } | |
| 6089 | |
|
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|
6090 virtual void work(uint worker_id) |
| 0 | 6091 { |
|
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|
6092 _task.work(worker_id); |
| 0 | 6093 } |
| 6094 }; | |
| 6095 | |
| 6096 CMSParKeepAliveClosure::CMSParKeepAliveClosure(CMSCollector* collector, | |
|
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|
6097 MemRegion span, CMSBitMap* bit_map, OopTaskQueue* work_queue): |
| 0 | 6098 _span(span), |
| 6099 _bit_map(bit_map), | |
| 6100 _work_queue(work_queue), | |
|
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|
6101 _mark_and_push(collector, span, bit_map, work_queue), |
| 0 | 6102 _low_water_mark(MIN2((uint)(work_queue->max_elems()/4), |
| 6103 (uint)(CMSWorkQueueDrainThreshold * ParallelGCThreads))) | |
| 6104 { } | |
| 6105 | |
| 6106 // . see if we can share work_queues with ParNew? XXX | |
| 6107 void CMSRefProcTaskProxy::do_work_steal(int i, | |
| 6108 CMSParDrainMarkingStackClosure* drain, | |
| 6109 CMSParKeepAliveClosure* keep_alive, | |
| 6110 int* seed) { | |
| 6111 OopTaskQueue* work_q = work_queue(i); | |
| 6112 NOT_PRODUCT(int num_steals = 0;) | |
| 6113 oop obj_to_scan; | |
| 6114 | |
| 6115 while (true) { | |
| 6116 // Completely finish any left over work from (an) earlier round(s) | |
| 6117 drain->trim_queue(0); | |
|
679
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|
6118 size_t num_from_overflow_list = MIN2((size_t)(work_q->max_elems() - work_q->size())/4, |
|
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|
6119 (size_t)ParGCDesiredObjsFromOverflowList); |
| 0 | 6120 // Now check if there's any work in the overflow list |
|
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|
6121 // Passing ParallelGCThreads as the third parameter, no_of_gc_threads, |
|
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|
6122 // only affects the number of attempts made to get work from the |
|
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|
6123 // overflow list and does not affect the number of workers. Just |
|
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|
6124 // pass ParallelGCThreads so this behavior is unchanged. |
| 0 | 6125 if (_collector->par_take_from_overflow_list(num_from_overflow_list, |
|
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|
6126 work_q, |
|
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|
6127 ParallelGCThreads)) { |
| 0 | 6128 // Found something in global overflow list; |
| 6129 // not yet ready to go stealing work from others. | |
| 6130 // We'd like to assert(work_q->size() != 0, ...) | |
| 6131 // because we just took work from the overflow list, | |
| 6132 // but of course we can't, since all of that might have | |
| 6133 // been already stolen from us. | |
| 6134 continue; | |
| 6135 } | |
| 6136 // Verify that we have no work before we resort to stealing | |
| 6137 assert(work_q->size() == 0, "Have work, shouldn't steal"); | |
| 6138 // Try to steal from other queues that have work | |
| 6139 if (task_queues()->steal(i, seed, /* reference */ obj_to_scan)) { | |
| 6140 NOT_PRODUCT(num_steals++;) | |
| 6141 assert(obj_to_scan->is_oop(), "Oops, not an oop!"); | |
| 6142 assert(_mark_bit_map->isMarked((HeapWord*)obj_to_scan), "Stole an unmarked oop?"); | |
| 6143 // Do scanning work | |
| 6144 obj_to_scan->oop_iterate(keep_alive); | |
| 6145 // Loop around, finish this work, and try to steal some more | |
| 6146 } else if (terminator()->offer_termination()) { | |
| 6147 break; // nirvana from the infinite cycle | |
| 6148 } | |
| 6149 } | |
| 6150 NOT_PRODUCT( | |
| 6151 if (PrintCMSStatistics != 0) { | |
| 6152 gclog_or_tty->print("\n\t(%d: stole %d oops)", i, num_steals); | |
| 6153 } | |
| 6154 ) | |
| 6155 } | |
| 6156 | |
| 6157 void CMSRefProcTaskExecutor::execute(ProcessTask& task) | |
| 6158 { | |
| 6159 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
|
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|
6160 FlexibleWorkGang* workers = gch->workers(); |
| 0 | 6161 assert(workers != NULL, "Need parallel worker threads."); |
| 6162 CMSRefProcTaskProxy rp_task(task, &_collector, | |
| 6163 _collector.ref_processor()->span(), | |
| 6164 _collector.markBitMap(), | |
|
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|
6165 workers, _collector.task_queues()); |
| 0 | 6166 workers->run_task(&rp_task); |
| 6167 } | |
| 6168 | |
| 6169 void CMSRefProcTaskExecutor::execute(EnqueueTask& task) | |
| 6170 { | |
| 6171 | |
| 6172 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
|
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|
6173 FlexibleWorkGang* workers = gch->workers(); |
| 0 | 6174 assert(workers != NULL, "Need parallel worker threads."); |
| 6175 CMSRefEnqueueTaskProxy enq_task(task); | |
| 6176 workers->run_task(&enq_task); | |
| 6177 } | |
| 6178 | |
| 6179 void CMSCollector::refProcessingWork(bool asynch, bool clear_all_soft_refs) { | |
| 6180 | |
| 6181 ResourceMark rm; | |
| 6182 HandleMark hm; | |
| 6183 | |
| 6184 ReferenceProcessor* rp = ref_processor(); | |
| 6185 assert(rp->span().equals(_span), "Spans should be equal"); | |
|
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|
6186 assert(!rp->enqueuing_is_done(), "Enqueuing should not be complete"); |
|
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|
6187 // Process weak references. |
|
457
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|
6188 rp->setup_policy(clear_all_soft_refs); |
|
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|
6189 verify_work_stacks_empty(); |
|
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|
6190 |
| 0 | 6191 CMSKeepAliveClosure cmsKeepAliveClosure(this, _span, &_markBitMap, |
|
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|
6192 &_markStack, false /* !preclean */); |
| 0 | 6193 CMSDrainMarkingStackClosure cmsDrainMarkingStackClosure(this, |
| 6194 _span, &_markBitMap, &_markStack, | |
|
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|
6195 &cmsKeepAliveClosure, false /* !preclean */); |
| 0 | 6196 { |
| 10405 | 6197 GCTraceTime t("weak refs processing", PrintGCDetails, false, _gc_timer_cm); |
| 6198 | |
| 6199 ReferenceProcessorStats stats; | |
| 0 | 6200 if (rp->processing_is_mt()) { |
|
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|
6201 // Set the degree of MT here. If the discovery is done MT, there |
|
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|
6202 // may have been a different number of threads doing the discovery |
|
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|
6203 // and a different number of discovered lists may have Ref objects. |
|
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|
6204 // That is OK as long as the Reference lists are balanced (see |
|
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|
6205 // balance_all_queues() and balance_queues()). |
|
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|
6206 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
|
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|
6207 int active_workers = ParallelGCThreads; |
|
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|
6208 FlexibleWorkGang* workers = gch->workers(); |
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|
6209 if (workers != NULL) { |
|
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|
6210 active_workers = workers->active_workers(); |
|
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|
6211 // The expectation is that active_workers will have already |
|
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|
6212 // been set to a reasonable value. If it has not been set, |
|
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|
6213 // investigate. |
|
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|
6214 assert(active_workers > 0, "Should have been set during scavenge"); |
|
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|
6215 } |
|
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|
6216 rp->set_active_mt_degree(active_workers); |
| 0 | 6217 CMSRefProcTaskExecutor task_executor(*this); |
| 10405 | 6218 stats = rp->process_discovered_references(&_is_alive_closure, |
| 0 | 6219 &cmsKeepAliveClosure, |
| 6220 &cmsDrainMarkingStackClosure, | |
| 10405 | 6221 &task_executor, |
| 6222 _gc_timer_cm); | |
| 0 | 6223 } else { |
| 10405 | 6224 stats = rp->process_discovered_references(&_is_alive_closure, |
| 0 | 6225 &cmsKeepAliveClosure, |
| 6226 &cmsDrainMarkingStackClosure, | |
| 10405 | 6227 NULL, |
| 6228 _gc_timer_cm); | |
| 6229 } | |
| 6230 _gc_tracer_cm->report_gc_reference_stats(stats); | |
| 6231 | |
|
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|
6232 } |
|
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|
6233 |
|
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|
6234 // This is the point where the entire marking should have completed. |
|
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|
6235 verify_work_stacks_empty(); |
| 0 | 6236 |
|
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|
6237 if (should_unload_classes()) { |
| 0 | 6238 { |
| 10405 | 6239 GCTraceTime t("class unloading", PrintGCDetails, false, _gc_timer_cm); |
| 0 | 6240 |
|
10188
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|
6241 // Unload classes and purge the SystemDictionary. |
| 0 | 6242 bool purged_class = SystemDictionary::do_unloading(&_is_alive_closure); |
| 6243 | |
|
10188
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|
6244 // Unload nmethods. |
|
6787
8966c2d65d96
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brutisso
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|
6245 CodeCache::do_unloading(&_is_alive_closure, purged_class); |
| 0 | 6246 |
|
10188
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|
6247 // Prune dead klasses from subklass/sibling/implementor lists. |
|
6725
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|
6248 Klass::clean_weak_klass_links(&_is_alive_closure); |
| 0 | 6249 } |
| 6250 | |
| 6251 { | |
| 10405 | 6252 GCTraceTime t("scrub symbol table", PrintGCDetails, false, _gc_timer_cm); |
|
2177
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|
6253 // Clean up unreferenced symbols in symbol table. |
|
3582bf76420e
6990754: Use native memory and reference counting to implement SymbolTable
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|
6254 SymbolTable::unlink(); |
| 0 | 6255 } |
| 6256 } | |
| 6257 | |
|
6725
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6258 // CMS doesn't use the StringTable as hard roots when class unloading is turned off. |
|
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|
6259 // Need to check if we really scanned the StringTable. |
|
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|
6260 if ((roots_scanning_options() & SharedHeap::SO_Strings) == 0) { |
| 10405 | 6261 GCTraceTime t("scrub string table", PrintGCDetails, false, _gc_timer_cm); |
|
10188
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|
6262 // Delete entries for dead interned strings. |
|
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|
6263 StringTable::unlink(&_is_alive_closure); |
|
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|
6264 } |
|
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|
6265 |
| 0 | 6266 // Restore any preserved marks as a result of mark stack or |
| 6267 // work queue overflow | |
| 6268 restore_preserved_marks_if_any(); // done single-threaded for now | |
| 6269 | |
| 6270 rp->set_enqueuing_is_done(true); | |
| 6271 if (rp->processing_is_mt()) { | |
|
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|
6272 rp->balance_all_queues(); |
| 0 | 6273 CMSRefProcTaskExecutor task_executor(*this); |
| 6274 rp->enqueue_discovered_references(&task_executor); | |
| 6275 } else { | |
| 6276 rp->enqueue_discovered_references(NULL); | |
| 6277 } | |
| 6278 rp->verify_no_references_recorded(); | |
| 6279 assert(!rp->discovery_enabled(), "should have been disabled"); | |
| 6280 } | |
| 6281 | |
| 6282 #ifndef PRODUCT | |
| 6283 void CMSCollector::check_correct_thread_executing() { | |
| 6284 Thread* t = Thread::current(); | |
| 6285 // Only the VM thread or the CMS thread should be here. | |
| 6286 assert(t->is_ConcurrentGC_thread() || t->is_VM_thread(), | |
| 6287 "Unexpected thread type"); | |
| 6288 // If this is the vm thread, the foreground process | |
| 6289 // should not be waiting. Note that _foregroundGCIsActive is | |
| 6290 // true while the foreground collector is waiting. | |
| 6291 if (_foregroundGCShouldWait) { | |
| 6292 // We cannot be the VM thread | |
| 6293 assert(t->is_ConcurrentGC_thread(), | |
| 6294 "Should be CMS thread"); | |
| 6295 } else { | |
| 6296 // We can be the CMS thread only if we are in a stop-world | |
| 6297 // phase of CMS collection. | |
| 6298 if (t->is_ConcurrentGC_thread()) { | |
| 6299 assert(_collectorState == InitialMarking || | |
| 6300 _collectorState == FinalMarking, | |
| 6301 "Should be a stop-world phase"); | |
| 6302 // The CMS thread should be holding the CMS_token. | |
| 6303 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 6304 "Potential interference with concurrently " | |
| 6305 "executing VM thread"); | |
| 6306 } | |
| 6307 } | |
| 6308 } | |
| 6309 #endif | |
| 6310 | |
| 6311 void CMSCollector::sweep(bool asynch) { | |
| 6312 assert(_collectorState == Sweeping, "just checking"); | |
| 6313 check_correct_thread_executing(); | |
| 6314 verify_work_stacks_empty(); | |
| 6315 verify_overflow_empty(); | |
|
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|
6316 increment_sweep_count(); |
|
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
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|
6317 TraceCMSMemoryManagerStats tms(_collectorState,GenCollectedHeap::heap()->gc_cause()); |
|
1703
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6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
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|
6318 |
|
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|
6319 _inter_sweep_timer.stop(); |
|
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|
6320 _inter_sweep_estimate.sample(_inter_sweep_timer.seconds()); |
| 0 | 6321 size_policy()->avg_cms_free_at_sweep()->sample(_cmsGen->free()); |
| 6322 | |
|
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|
6323 assert(!_intra_sweep_timer.is_active(), "Should not be active"); |
|
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|
6324 _intra_sweep_timer.reset(); |
|
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|
6325 _intra_sweep_timer.start(); |
| 0 | 6326 if (asynch) { |
| 6327 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
| 6328 CMSPhaseAccounting pa(this, "sweep", !PrintGCDetails); | |
|
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diff
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|
6329 // First sweep the old gen |
| 0 | 6330 { |
| 6331 CMSTokenSyncWithLocks ts(true, _cmsGen->freelistLock(), | |
| 6332 bitMapLock()); | |
| 6333 sweepWork(_cmsGen, asynch); | |
| 6334 } | |
| 6335 | |
| 6336 // Update Universe::_heap_*_at_gc figures. | |
| 6337 // We need all the free list locks to make the abstract state | |
| 6338 // transition from Sweeping to Resetting. See detailed note | |
| 6339 // further below. | |
| 6340 { | |
|
6725
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|
6341 CMSTokenSyncWithLocks ts(true, _cmsGen->freelistLock()); |
| 0 | 6342 // Update heap occupancy information which is used as |
| 6343 // input to soft ref clearing policy at the next gc. | |
| 6344 Universe::update_heap_info_at_gc(); | |
| 6345 _collectorState = Resizing; | |
| 6346 } | |
| 6347 } else { | |
| 6348 // already have needed locks | |
| 6349 sweepWork(_cmsGen, asynch); | |
| 6350 // Update heap occupancy information which is used as | |
| 6351 // input to soft ref clearing policy at the next gc. | |
| 6352 Universe::update_heap_info_at_gc(); | |
| 6353 _collectorState = Resizing; | |
| 6354 } | |
| 6355 verify_work_stacks_empty(); | |
| 6356 verify_overflow_empty(); | |
| 6357 | |
|
8784
79af1312fc2c
8005602: NPG: classunloading does not happen while CMS GC with -XX:+CMSClassUnloadingEnabled is used
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diff
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|
6358 if (should_unload_classes()) { |
|
79af1312fc2c
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mgerdin
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diff
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|
6359 ClassLoaderDataGraph::purge(); |
|
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|
6360 } |
|
79af1312fc2c
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|
6361 |
|
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|
6362 _intra_sweep_timer.stop(); |
|
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|
6363 _intra_sweep_estimate.sample(_intra_sweep_timer.seconds()); |
|
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|
6364 |
|
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|
6365 _inter_sweep_timer.reset(); |
|
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changeset
|
6366 _inter_sweep_timer.start(); |
| 0 | 6367 |
| 14309 | 6368 // We need to use a monotonically non-decreasing time in ms |
| 4911 | 6369 // or we will see time-warp warnings and os::javaTimeMillis() |
| 6370 // does not guarantee monotonicity. | |
| 6371 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; | |
| 6372 update_time_of_last_gc(now); | |
| 0 | 6373 |
| 6374 // NOTE on abstract state transitions: | |
| 6375 // Mutators allocate-live and/or mark the mod-union table dirty | |
| 6376 // based on the state of the collection. The former is done in | |
| 6377 // the interval [Marking, Sweeping] and the latter in the interval | |
| 6378 // [Marking, Sweeping). Thus the transitions into the Marking state | |
| 6379 // and out of the Sweeping state must be synchronously visible | |
| 6380 // globally to the mutators. | |
| 6381 // The transition into the Marking state happens with the world | |
| 6382 // stopped so the mutators will globally see it. Sweeping is | |
| 6383 // done asynchronously by the background collector so the transition | |
| 6384 // from the Sweeping state to the Resizing state must be done | |
| 6385 // under the freelistLock (as is the check for whether to | |
| 6386 // allocate-live and whether to dirty the mod-union table). | |
| 6387 assert(_collectorState == Resizing, "Change of collector state to" | |
| 6388 " Resizing must be done under the freelistLocks (plural)"); | |
| 6389 | |
|
1888
a7214d79fcf1
6896603: CMS/GCH: collection_attempt_is_safe() ergo should use more recent data
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1837
diff
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|
6390 // Now that sweeping has been completed, we clear |
|
a7214d79fcf1
6896603: CMS/GCH: collection_attempt_is_safe() ergo should use more recent data
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1837
diff
changeset
|
6391 // the incremental_collection_failed flag, |
| 0 | 6392 // thus inviting a younger gen collection to promote into |
| 6393 // this generation. If such a promotion may still fail, | |
| 6394 // the flag will be set again when a young collection is | |
| 6395 // attempted. | |
| 6396 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
|
1888
a7214d79fcf1
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diff
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|
6397 gch->clear_incremental_collection_failed(); // Worth retrying as fresh space may have been freed up |
| 0 | 6398 gch->update_full_collections_completed(_collection_count_start); |
| 6399 } | |
| 6400 | |
| 6401 // FIX ME!!! Looks like this belongs in CFLSpace, with | |
| 6402 // CMSGen merely delegating to it. | |
| 6403 void ConcurrentMarkSweepGeneration::setNearLargestChunk() { | |
|
1145
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diff
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|
6404 double nearLargestPercent = FLSLargestBlockCoalesceProximity; |
| 0 | 6405 HeapWord* minAddr = _cmsSpace->bottom(); |
| 6406 HeapWord* largestAddr = | |
|
6028
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
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6026
diff
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|
6407 (HeapWord*) _cmsSpace->dictionary()->find_largest_dict(); |
|
1145
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diff
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|
6408 if (largestAddr == NULL) { |
| 0 | 6409 // The dictionary appears to be empty. In this case |
| 6410 // try to coalesce at the end of the heap. | |
| 6411 largestAddr = _cmsSpace->end(); | |
| 6412 } | |
| 6413 size_t largestOffset = pointer_delta(largestAddr, minAddr); | |
| 6414 size_t nearLargestOffset = | |
| 6415 (size_t)((double)largestOffset * nearLargestPercent) - MinChunkSize; | |
|
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|
6416 if (PrintFLSStatistics != 0) { |
|
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6631166: CMS: better heuristics when combatting fragmentation
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|
6417 gclog_or_tty->print_cr( |
|
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6631166: CMS: better heuristics when combatting fragmentation
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diff
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|
6418 "CMS: Large Block: " PTR_FORMAT ";" |
|
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
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diff
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|
6419 " Proximity: " PTR_FORMAT " -> " PTR_FORMAT, |
|
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6631166: CMS: better heuristics when combatting fragmentation
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1085
diff
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|
6420 largestAddr, |
|
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|
6421 _cmsSpace->nearLargestChunk(), minAddr + nearLargestOffset); |
|
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|
6422 } |
| 0 | 6423 _cmsSpace->set_nearLargestChunk(minAddr + nearLargestOffset); |
| 6424 } | |
| 6425 | |
| 6426 bool ConcurrentMarkSweepGeneration::isNearLargestChunk(HeapWord* addr) { | |
| 6427 return addr >= _cmsSpace->nearLargestChunk(); | |
| 6428 } | |
| 6429 | |
| 6430 FreeChunk* ConcurrentMarkSweepGeneration::find_chunk_at_end() { | |
| 6431 return _cmsSpace->find_chunk_at_end(); | |
| 6432 } | |
| 6433 | |
| 6434 void ConcurrentMarkSweepGeneration::update_gc_stats(int current_level, | |
| 6435 bool full) { | |
| 6436 // The next lower level has been collected. Gather any statistics | |
| 6437 // that are of interest at this point. | |
| 6438 if (!full && (current_level + 1) == level()) { | |
| 6439 // Gather statistics on the young generation collection. | |
| 6440 collector()->stats().record_gc0_end(used()); | |
| 6441 } | |
| 6442 } | |
| 6443 | |
| 6444 CMSAdaptiveSizePolicy* ConcurrentMarkSweepGeneration::size_policy() { | |
| 6445 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 6446 assert(gch->kind() == CollectedHeap::GenCollectedHeap, | |
| 6447 "Wrong type of heap"); | |
| 6448 CMSAdaptiveSizePolicy* sp = (CMSAdaptiveSizePolicy*) | |
| 6449 gch->gen_policy()->size_policy(); | |
| 6450 assert(sp->is_gc_cms_adaptive_size_policy(), | |
| 6451 "Wrong type of size policy"); | |
| 6452 return sp; | |
| 6453 } | |
| 6454 | |
| 6455 void ConcurrentMarkSweepGeneration::rotate_debug_collection_type() { | |
| 6456 if (PrintGCDetails && Verbose) { | |
| 6457 gclog_or_tty->print("Rotate from %d ", _debug_collection_type); | |
| 6458 } | |
| 6459 _debug_collection_type = (CollectionTypes) (_debug_collection_type + 1); | |
| 6460 _debug_collection_type = | |
| 6461 (CollectionTypes) (_debug_collection_type % Unknown_collection_type); | |
| 6462 if (PrintGCDetails && Verbose) { | |
| 6463 gclog_or_tty->print_cr("to %d ", _debug_collection_type); | |
| 6464 } | |
| 6465 } | |
| 6466 | |
| 6467 void CMSCollector::sweepWork(ConcurrentMarkSweepGeneration* gen, | |
| 6468 bool asynch) { | |
| 6469 // We iterate over the space(s) underlying this generation, | |
| 6470 // checking the mark bit map to see if the bits corresponding | |
| 6471 // to specific blocks are marked or not. Blocks that are | |
| 6472 // marked are live and are not swept up. All remaining blocks | |
| 6473 // are swept up, with coalescing on-the-fly as we sweep up | |
| 6474 // contiguous free and/or garbage blocks: | |
| 6475 // We need to ensure that the sweeper synchronizes with allocators | |
| 6476 // and stop-the-world collectors. In particular, the following | |
| 6477 // locks are used: | |
| 6478 // . CMS token: if this is held, a stop the world collection cannot occur | |
| 6479 // . freelistLock: if this is held no allocation can occur from this | |
| 6480 // generation by another thread | |
| 6481 // . bitMapLock: if this is held, no other thread can access or update | |
| 6482 // | |
| 6483 | |
| 6484 // Note that we need to hold the freelistLock if we use | |
| 6485 // block iterate below; else the iterator might go awry if | |
| 6486 // a mutator (or promotion) causes block contents to change | |
| 6487 // (for instance if the allocator divvies up a block). | |
| 6488 // If we hold the free list lock, for all practical purposes | |
| 6489 // young generation GC's can't occur (they'll usually need to | |
| 6490 // promote), so we might as well prevent all young generation | |
| 6491 // GC's while we do a sweeping step. For the same reason, we might | |
| 6492 // as well take the bit map lock for the entire duration | |
| 6493 | |
| 6494 // check that we hold the requisite locks | |
| 6495 assert(have_cms_token(), "Should hold cms token"); | |
| 6496 assert( (asynch && ConcurrentMarkSweepThread::cms_thread_has_cms_token()) | |
| 6497 || (!asynch && ConcurrentMarkSweepThread::vm_thread_has_cms_token()), | |
| 6498 "Should possess CMS token to sweep"); | |
| 6499 assert_lock_strong(gen->freelistLock()); | |
| 6500 assert_lock_strong(bitMapLock()); | |
| 6501 | |
|
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|
6502 assert(!_inter_sweep_timer.is_active(), "Was switched off in an outer context"); |
|
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|
6503 assert(_intra_sweep_timer.is_active(), "Was switched on in an outer context"); |
|
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|
6504 gen->cmsSpace()->beginSweepFLCensus((float)(_inter_sweep_timer.seconds()), |
|
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|
6505 _inter_sweep_estimate.padded_average(), |
|
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|
6506 _intra_sweep_estimate.padded_average()); |
| 0 | 6507 gen->setNearLargestChunk(); |
| 6508 | |
| 6509 { | |
| 6510 SweepClosure sweepClosure(this, gen, &_markBitMap, | |
| 6511 CMSYield && asynch); | |
| 6512 gen->cmsSpace()->blk_iterate_careful(&sweepClosure); | |
| 6513 // We need to free-up/coalesce garbage/blocks from a | |
| 6514 // co-terminal free run. This is done in the SweepClosure | |
| 6515 // destructor; so, do not remove this scope, else the | |
| 6516 // end-of-sweep-census below will be off by a little bit. | |
| 6517 } | |
| 6518 gen->cmsSpace()->sweep_completed(); | |
|
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|
6519 gen->cmsSpace()->endSweepFLCensus(sweep_count()); |
|
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9
diff
changeset
|
6520 if (should_unload_classes()) { // unloaded classes this cycle, |
|
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
6521 _concurrent_cycles_since_last_unload = 0; // ... reset count |
|
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
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parents:
9
diff
changeset
|
6522 } else { // did not unload classes, |
|
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
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parents:
9
diff
changeset
|
6523 _concurrent_cycles_since_last_unload++; // ... increment count |
|
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
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parents:
9
diff
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|
6524 } |
| 0 | 6525 } |
| 6526 | |
| 6527 // Reset CMS data structures (for now just the marking bit map) | |
| 6528 // preparatory for the next cycle. | |
| 6529 void CMSCollector::reset(bool asynch) { | |
| 6530 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 6531 CMSAdaptiveSizePolicy* sp = size_policy(); | |
| 6532 AdaptiveSizePolicyOutput(sp, gch->total_collections()); | |
| 6533 if (asynch) { | |
| 6534 CMSTokenSyncWithLocks ts(true, bitMapLock()); | |
| 6535 | |
| 6536 // If the state is not "Resetting", the foreground thread | |
| 6537 // has done a collection and the resetting. | |
| 6538 if (_collectorState != Resetting) { | |
| 6539 assert(_collectorState == Idling, "The state should only change" | |
| 6540 " because the foreground collector has finished the collection"); | |
| 6541 return; | |
| 6542 } | |
| 6543 | |
| 6544 // Clear the mark bitmap (no grey objects to start with) | |
| 6545 // for the next cycle. | |
| 6546 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
| 6547 CMSPhaseAccounting cmspa(this, "reset", !PrintGCDetails); | |
| 6548 | |
| 6549 HeapWord* curAddr = _markBitMap.startWord(); | |
| 6550 while (curAddr < _markBitMap.endWord()) { | |
| 6551 size_t remaining = pointer_delta(_markBitMap.endWord(), curAddr); | |
| 6552 MemRegion chunk(curAddr, MIN2(CMSBitMapYieldQuantum, remaining)); | |
| 6553 _markBitMap.clear_large_range(chunk); | |
| 6554 if (ConcurrentMarkSweepThread::should_yield() && | |
| 6555 !foregroundGCIsActive() && | |
| 6556 CMSYield) { | |
| 6557 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 6558 "CMS thread should hold CMS token"); | |
| 6559 assert_lock_strong(bitMapLock()); | |
| 6560 bitMapLock()->unlock(); | |
| 6561 ConcurrentMarkSweepThread::desynchronize(true); | |
| 6562 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 6563 stopTimer(); | |
| 6564 if (PrintCMSStatistics != 0) { | |
| 6565 incrementYields(); | |
| 6566 } | |
| 6567 icms_wait(); | |
| 6568 | |
| 6569 // See the comment in coordinator_yield() | |
| 6570 for (unsigned i = 0; i < CMSYieldSleepCount && | |
|
113
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94
diff
changeset
|
6571 ConcurrentMarkSweepThread::should_yield() && |
|
ba764ed4b6f2
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parents:
94
diff
changeset
|
6572 !CMSCollector::foregroundGCIsActive(); ++i) { |
| 0 | 6573 os::sleep(Thread::current(), 1, false); |
| 6574 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 6575 } | |
| 6576 | |
| 6577 ConcurrentMarkSweepThread::synchronize(true); | |
| 6578 bitMapLock()->lock_without_safepoint_check(); | |
| 6579 startTimer(); | |
| 6580 } | |
| 6581 curAddr = chunk.end(); | |
| 6582 } | |
|
1387
0bfd3fb24150
6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
jmasa
parents:
1289
diff
changeset
|
6583 // 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
|
6584 // 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
|
6585 // 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
|
6586 // and count. |
|
0bfd3fb24150
6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
jmasa
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1289
diff
changeset
|
6587 sp->reset_gc_overhead_limit_count(); |
| 0 | 6588 _collectorState = Idling; |
| 6589 } else { | |
| 6590 // already have the lock | |
| 6591 assert(_collectorState == Resetting, "just checking"); | |
| 6592 assert_lock_strong(bitMapLock()); | |
| 6593 _markBitMap.clear_all(); | |
| 6594 _collectorState = Idling; | |
| 6595 } | |
| 6596 | |
| 6597 // Stop incremental mode after a cycle completes, so that any future cycles | |
| 6598 // are triggered by allocation. | |
| 6599 stop_icms(); | |
| 6600 | |
| 6601 NOT_PRODUCT( | |
| 6602 if (RotateCMSCollectionTypes) { | |
| 6603 _cmsGen->rotate_debug_collection_type(); | |
| 6604 } | |
| 6605 ) | |
| 10405 | 6606 |
| 6607 register_gc_end(); | |
| 0 | 6608 } |
| 6609 | |
|
6064
9d679effd28c
7166894: Add gc cause to GC logging for all collectors
brutisso
parents:
6028
diff
changeset
|
6610 void CMSCollector::do_CMS_operation(CMS_op_type op, GCCause::Cause gc_cause) { |
| 0 | 6611 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps); |
| 6612 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
| 10405 | 6613 GCTraceTime t(GCCauseString("GC", gc_cause), PrintGC, !PrintGCDetails, NULL); |
| 0 | 6614 TraceCollectorStats tcs(counters()); |
| 6615 | |
| 6616 switch (op) { | |
| 6617 case CMS_op_checkpointRootsInitial: { | |
|
2125
7246a374a9f2
6458402: 3 jvmti tests fail with CMS and +ExplicitGCInvokesConcurrent
kamg
parents:
1994
diff
changeset
|
6618 SvcGCMarker sgcm(SvcGCMarker::OTHER); |
| 0 | 6619 checkpointRootsInitial(true); // asynch |
| 6620 if (PrintGC) { | |
| 6621 _cmsGen->printOccupancy("initial-mark"); | |
| 6622 } | |
| 6623 break; | |
| 6624 } | |
| 6625 case CMS_op_checkpointRootsFinal: { | |
|
2125
7246a374a9f2
6458402: 3 jvmti tests fail with CMS and +ExplicitGCInvokesConcurrent
kamg
parents:
1994
diff
changeset
|
6626 SvcGCMarker sgcm(SvcGCMarker::OTHER); |
| 0 | 6627 checkpointRootsFinal(true, // asynch |
| 6628 false, // !clear_all_soft_refs | |
| 6629 false); // !init_mark_was_synchronous | |
| 6630 if (PrintGC) { | |
| 6631 _cmsGen->printOccupancy("remark"); | |
| 6632 } | |
| 6633 break; | |
| 6634 } | |
| 6635 default: | |
| 6636 fatal("No such CMS_op"); | |
| 6637 } | |
| 6638 } | |
| 6639 | |
| 6640 #ifndef PRODUCT | |
| 6641 size_t const CMSCollector::skip_header_HeapWords() { | |
| 6642 return FreeChunk::header_size(); | |
| 6643 } | |
| 6644 | |
| 6645 // Try and collect here conditions that should hold when | |
| 6646 // CMS thread is exiting. The idea is that the foreground GC | |
| 6647 // thread should not be blocked if it wants to terminate | |
| 6648 // the CMS thread and yet continue to run the VM for a while | |
| 6649 // after that. | |
| 6650 void CMSCollector::verify_ok_to_terminate() const { | |
| 6651 assert(Thread::current()->is_ConcurrentGC_thread(), | |
| 6652 "should be called by CMS thread"); | |
| 6653 assert(!_foregroundGCShouldWait, "should be false"); | |
| 6654 // We could check here that all the various low-level locks | |
| 6655 // are not held by the CMS thread, but that is overkill; see | |
| 6656 // also CMSThread::verify_ok_to_terminate() where the CGC_lock | |
| 6657 // is checked. | |
| 6658 } | |
| 6659 #endif | |
| 6660 | |
| 6661 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
|
6662 assert(_markBitMap.isMarked(addr) && _markBitMap.isMarked(addr + 1), |
|
c96030fff130
6684579: SoftReference processing can be made more efficient
ysr
parents:
452
diff
changeset
|
6663 "missing Printezis mark?"); |
| 0 | 6664 HeapWord* nextOneAddr = _markBitMap.getNextMarkedWordAddress(addr + 2); |
| 6665 size_t size = pointer_delta(nextOneAddr + 1, addr); | |
| 6666 assert(size == CompactibleFreeListSpace::adjustObjectSize(size), | |
| 6667 "alignment problem"); | |
| 6668 assert(size >= 3, "Necessary for Printezis marks to work"); | |
| 6669 return size; | |
| 6670 } | |
| 6671 | |
| 6672 // A variant of the above (block_size_using_printezis_bits()) except | |
| 6673 // that we return 0 if the P-bits are not yet set. | |
| 6674 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
|
6675 if (_markBitMap.isMarked(addr + 1)) { |
|
c5a923563727
6912621: iCMS: Error: assert(_markBitMap.isMarked(addr + 1),"Missing Printezis bit?")
ysr
parents:
2177
diff
changeset
|
6676 assert(_markBitMap.isMarked(addr), "P-bit can be set only for marked objects"); |
| 0 | 6677 HeapWord* nextOneAddr = _markBitMap.getNextMarkedWordAddress(addr + 2); |
| 6678 size_t size = pointer_delta(nextOneAddr + 1, addr); | |
| 6679 assert(size == CompactibleFreeListSpace::adjustObjectSize(size), | |
| 6680 "alignment problem"); | |
| 6681 assert(size >= 3, "Necessary for Printezis marks to work"); | |
| 6682 return size; | |
|
2226
c5a923563727
6912621: iCMS: Error: assert(_markBitMap.isMarked(addr + 1),"Missing Printezis bit?")
ysr
parents:
2177
diff
changeset
|
6683 } |
|
c5a923563727
6912621: iCMS: Error: assert(_markBitMap.isMarked(addr + 1),"Missing Printezis bit?")
ysr
parents:
2177
diff
changeset
|
6684 return 0; |
| 0 | 6685 } |
| 6686 | |
| 6687 HeapWord* CMSCollector::next_card_start_after_block(HeapWord* addr) const { | |
| 6688 size_t sz = 0; | |
| 6689 oop p = (oop)addr; | |
|
6725
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
6690 if (p->klass_or_null() != NULL) { |
| 0 | 6691 sz = CompactibleFreeListSpace::adjustObjectSize(p->size()); |
| 6692 } else { | |
| 6693 sz = block_size_using_printezis_bits(addr); | |
| 6694 } | |
| 6695 assert(sz > 0, "size must be nonzero"); | |
| 6696 HeapWord* next_block = addr + sz; | |
| 6697 HeapWord* next_card = (HeapWord*)round_to((uintptr_t)next_block, | |
| 6698 CardTableModRefBS::card_size); | |
| 6699 assert(round_down((uintptr_t)addr, CardTableModRefBS::card_size) < | |
| 6700 round_down((uintptr_t)next_card, CardTableModRefBS::card_size), | |
| 6701 "must be different cards"); | |
| 6702 return next_card; | |
| 6703 } | |
| 6704 | |
| 6705 | |
| 6706 // CMS Bit Map Wrapper ///////////////////////////////////////// | |
| 6707 | |
| 6708 // Construct a CMS bit map infrastructure, but don't create the | |
| 6709 // bit vector itself. That is done by a separate call CMSBitMap::allocate() | |
| 6710 // further below. | |
| 6711 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
|
6712 _bm(), |
| 0 | 6713 _shifter(shifter), |
| 6714 _lock(mutex_rank >= 0 ? new Mutex(mutex_rank, mutex_name, true) : NULL) | |
| 6715 { | |
| 6716 _bmStartWord = 0; | |
| 6717 _bmWordSize = 0; | |
| 6718 } | |
| 6719 | |
| 6720 bool CMSBitMap::allocate(MemRegion mr) { | |
| 6721 _bmStartWord = mr.start(); | |
| 6722 _bmWordSize = mr.word_size(); | |
| 6723 ReservedSpace brs(ReservedSpace::allocation_align_size_up( | |
| 6724 (_bmWordSize >> (_shifter + LogBitsPerByte)) + 1)); | |
| 6725 if (!brs.is_reserved()) { | |
| 6726 warning("CMS bit map allocation failure"); | |
| 6727 return false; | |
| 6728 } | |
| 14309 | 6729 // For now we'll just commit all of the bit map up front. |
| 0 | 6730 // Later on we'll try to be more parsimonious with swap. |
| 6731 if (!_virtual_space.initialize(brs, brs.size())) { | |
| 6732 warning("CMS bit map backing store failure"); | |
| 6733 return false; | |
| 6734 } | |
| 6735 assert(_virtual_space.committed_size() == brs.size(), | |
| 6736 "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
|
6737 _bm.set_map((BitMap::bm_word_t*)_virtual_space.low()); |
| 0 | 6738 assert(_virtual_space.committed_size() << (_shifter + LogBitsPerByte) >= |
| 6739 _bmWordSize, "inconsistency in bit map sizing"); | |
| 6740 _bm.set_size(_bmWordSize >> _shifter); | |
| 6741 | |
| 6742 // bm.clear(); // can we rely on getting zero'd memory? verify below | |
| 6743 assert(isAllClear(), | |
| 6744 "Expected zero'd memory from ReservedSpace constructor"); | |
| 6745 assert(_bm.size() == heapWordDiffToOffsetDiff(sizeInWords()), | |
| 6746 "consistency check"); | |
| 6747 return true; | |
| 6748 } | |
| 6749 | |
| 6750 void CMSBitMap::dirty_range_iterate_clear(MemRegion mr, MemRegionClosure* cl) { | |
| 6751 HeapWord *next_addr, *end_addr, *last_addr; | |
| 6752 assert_locked(); | |
| 6753 assert(covers(mr), "out-of-range error"); | |
| 6754 // XXX assert that start and end are appropriately aligned | |
| 6755 for (next_addr = mr.start(), end_addr = mr.end(); | |
| 6756 next_addr < end_addr; next_addr = last_addr) { | |
| 6757 MemRegion dirty_region = getAndClearMarkedRegion(next_addr, end_addr); | |
| 6758 last_addr = dirty_region.end(); | |
| 6759 if (!dirty_region.is_empty()) { | |
| 6760 cl->do_MemRegion(dirty_region); | |
| 6761 } else { | |
| 6762 assert(last_addr == end_addr, "program logic"); | |
| 6763 return; | |
| 6764 } | |
| 6765 } | |
| 6766 } | |
| 6767 | |
|
9076
7b835924c31c
8011872: Include Bit Map addresses in the hs_err files
stefank
parents:
9072
diff
changeset
|
6768 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
|
6769 _bm.print_on_error(st, prefix); |
|
7b835924c31c
8011872: Include Bit Map addresses in the hs_err files
stefank
parents:
9072
diff
changeset
|
6770 } |
|
7b835924c31c
8011872: Include Bit Map addresses in the hs_err files
stefank
parents:
9072
diff
changeset
|
6771 |
| 0 | 6772 #ifndef PRODUCT |
| 6773 void CMSBitMap::assert_locked() const { | |
| 6774 CMSLockVerifier::assert_locked(lock()); | |
| 6775 } | |
| 6776 | |
| 6777 bool CMSBitMap::covers(MemRegion mr) const { | |
| 6778 // assert(_bm.map() == _virtual_space.low(), "map inconsistency"); | |
| 6779 assert((size_t)_bm.size() == (_bmWordSize >> _shifter), | |
| 6780 "size inconsistency"); | |
| 6781 return (mr.start() >= _bmStartWord) && | |
| 6782 (mr.end() <= endWord()); | |
| 6783 } | |
| 6784 | |
| 6785 bool CMSBitMap::covers(HeapWord* start, size_t size) const { | |
| 6786 return (start >= _bmStartWord && (start + size) <= endWord()); | |
| 6787 } | |
| 6788 | |
| 6789 void CMSBitMap::verifyNoOneBitsInRange(HeapWord* left, HeapWord* right) { | |
| 6790 // verify that there are no 1 bits in the interval [left, right) | |
| 6791 FalseBitMapClosure falseBitMapClosure; | |
| 6792 iterate(&falseBitMapClosure, left, right); | |
| 6793 } | |
| 6794 | |
| 6795 void CMSBitMap::region_invariant(MemRegion mr) | |
| 6796 { | |
| 6797 assert_locked(); | |
| 6798 // mr = mr.intersection(MemRegion(_bmStartWord, _bmWordSize)); | |
| 6799 assert(!mr.is_empty(), "unexpected empty region"); | |
| 6800 assert(covers(mr), "mr should be covered by bit map"); | |
| 6801 // convert address range into offset range | |
| 6802 size_t start_ofs = heapWordToOffset(mr.start()); | |
| 6803 // Make sure that end() is appropriately aligned | |
| 6804 assert(mr.end() == (HeapWord*)round_to((intptr_t)mr.end(), | |
| 6805 (1 << (_shifter+LogHeapWordSize))), | |
| 6806 "Misaligned mr.end()"); | |
| 6807 size_t end_ofs = heapWordToOffset(mr.end()); | |
| 6808 assert(end_ofs > start_ofs, "Should mark at least one bit"); | |
| 6809 } | |
| 6810 | |
| 6811 #endif | |
| 6812 | |
| 6813 bool CMSMarkStack::allocate(size_t size) { | |
| 6814 // allocate a stack of the requisite depth | |
| 6815 ReservedSpace rs(ReservedSpace::allocation_align_size_up( | |
| 6816 size * sizeof(oop))); | |
| 6817 if (!rs.is_reserved()) { | |
| 6818 warning("CMSMarkStack allocation failure"); | |
| 6819 return false; | |
| 6820 } | |
| 6821 if (!_virtual_space.initialize(rs, rs.size())) { | |
| 6822 warning("CMSMarkStack backing store failure"); | |
| 6823 return false; | |
| 6824 } | |
| 6825 assert(_virtual_space.committed_size() == rs.size(), | |
| 6826 "didn't reserve backing store for all of CMS stack?"); | |
| 6827 _base = (oop*)(_virtual_space.low()); | |
| 6828 _index = 0; | |
| 6829 _capacity = size; | |
| 6830 NOT_PRODUCT(_max_depth = 0); | |
| 6831 return true; | |
| 6832 } | |
| 6833 | |
| 6834 // XXX FIX ME !!! In the MT case we come in here holding a | |
| 6835 // leaf lock. For printing we need to take a further lock | |
| 14309 | 6836 // which has lower rank. We need to recalibrate the two |
| 6837 // lock-ranks involved in order to be able to print the | |
| 0 | 6838 // messages below. (Or defer the printing to the caller. |
| 6839 // For now we take the expedient path of just disabling the | |
| 6840 // messages for the problematic case.) | |
| 6841 void CMSMarkStack::expand() { | |
| 1284 | 6842 assert(_capacity <= MarkStackSizeMax, "stack bigger than permitted"); |
| 6843 if (_capacity == MarkStackSizeMax) { | |
| 0 | 6844 if (_hit_limit++ == 0 && !CMSConcurrentMTEnabled && PrintGCDetails) { |
| 6845 // We print a warning message only once per CMS cycle. | |
| 6846 gclog_or_tty->print_cr(" (benign) Hit CMSMarkStack max size limit"); | |
| 6847 } | |
| 6848 return; | |
| 6849 } | |
| 6850 // Double capacity if possible | |
| 1284 | 6851 size_t new_capacity = MIN2(_capacity*2, MarkStackSizeMax); |
| 0 | 6852 // Do not give up existing stack until we have managed to |
| 6853 // get the double capacity that we desired. | |
| 6854 ReservedSpace rs(ReservedSpace::allocation_align_size_up( | |
| 6855 new_capacity * sizeof(oop))); | |
| 6856 if (rs.is_reserved()) { | |
| 6857 // Release the backing store associated with old stack | |
| 6858 _virtual_space.release(); | |
| 6859 // Reinitialize virtual space for new stack | |
| 6860 if (!_virtual_space.initialize(rs, rs.size())) { | |
| 6861 fatal("Not enough swap for expanded marking stack"); | |
| 6862 } | |
| 6863 _base = (oop*)(_virtual_space.low()); | |
| 6864 _index = 0; | |
| 6865 _capacity = new_capacity; | |
| 6866 } else if (_failed_double++ == 0 && !CMSConcurrentMTEnabled && PrintGCDetails) { | |
| 6867 // Failed to double capacity, continue; | |
| 6868 // we print a detail message only once per CMS cycle. | |
| 6869 gclog_or_tty->print(" (benign) Failed to expand marking stack from "SIZE_FORMAT"K to " | |
| 6870 SIZE_FORMAT"K", | |
| 6871 _capacity / K, new_capacity / K); | |
| 6872 } | |
| 6873 } | |
| 6874 | |
| 6875 | |
| 6876 // Closures | |
| 6877 // XXX: there seems to be a lot of code duplication here; | |
| 6878 // should refactor and consolidate common code. | |
| 6879 | |
| 6880 // This closure is used to mark refs into the CMS generation in | |
| 6881 // the CMS bit map. Called at the first checkpoint. This closure | |
| 6882 // assumes that we do not need to re-mark dirty cards; if the CMS | |
|
6725
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
6883 // generation on which this is used is not an oldest |
| 0 | 6884 // generation then this will lose younger_gen cards! |
| 6885 | |
| 6886 MarkRefsIntoClosure::MarkRefsIntoClosure( | |
|
994
753cf9794df9
6885169: merge of 4957990 and 6863023 causes conflict on do_nmethods
jrose
parents:
993
diff
changeset
|
6887 MemRegion span, CMSBitMap* bitMap): |
| 0 | 6888 _span(span), |
|
994
753cf9794df9
6885169: merge of 4957990 and 6863023 causes conflict on do_nmethods
jrose
parents:
993
diff
changeset
|
6889 _bitMap(bitMap) |
| 0 | 6890 { |
| 6891 assert(_ref_processor == NULL, "deliberately left NULL"); | |
| 6892 assert(_bitMap->covers(_span), "_bitMap/_span mismatch"); | |
| 6893 } | |
| 6894 | |
|
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6895 void MarkRefsIntoClosure::do_oop(oop obj) { |
| 0 | 6896 // if p points into _span, then mark corresponding bit in _markBitMap |
|
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
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6897 assert(obj->is_oop(), "expected an oop"); |
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6898 HeapWord* addr = (HeapWord*)obj; |
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6899 if (_span.contains(addr)) { |
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6900 // this should be made more efficient |
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6901 _bitMap->mark(addr); |
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6902 } |
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6903 } |
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6904 |
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6905 void MarkRefsIntoClosure::do_oop(oop* p) { MarkRefsIntoClosure::do_oop_work(p); } |
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6906 void MarkRefsIntoClosure::do_oop(narrowOop* p) { MarkRefsIntoClosure::do_oop_work(p); } |
| 0 | 6907 |
| 11975 | 6908 Par_MarkRefsIntoClosure::Par_MarkRefsIntoClosure( |
| 6909 MemRegion span, CMSBitMap* bitMap): | |
| 6910 _span(span), | |
| 6911 _bitMap(bitMap) | |
| 6912 { | |
| 6913 assert(_ref_processor == NULL, "deliberately left NULL"); | |
| 6914 assert(_bitMap->covers(_span), "_bitMap/_span mismatch"); | |
| 6915 } | |
| 6916 | |
| 6917 void Par_MarkRefsIntoClosure::do_oop(oop obj) { | |
| 6918 // if p points into _span, then mark corresponding bit in _markBitMap | |
| 6919 assert(obj->is_oop(), "expected an oop"); | |
| 6920 HeapWord* addr = (HeapWord*)obj; | |
| 6921 if (_span.contains(addr)) { | |
| 6922 // this should be made more efficient | |
| 6923 _bitMap->par_mark(addr); | |
| 6924 } | |
| 6925 } | |
| 6926 | |
| 6927 void Par_MarkRefsIntoClosure::do_oop(oop* p) { Par_MarkRefsIntoClosure::do_oop_work(p); } | |
| 6928 void Par_MarkRefsIntoClosure::do_oop(narrowOop* p) { Par_MarkRefsIntoClosure::do_oop_work(p); } | |
| 6929 | |
| 0 | 6930 // A variant of the above, used for CMS marking verification. |
| 6931 MarkRefsIntoVerifyClosure::MarkRefsIntoVerifyClosure( | |
|
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6932 MemRegion span, CMSBitMap* verification_bm, CMSBitMap* cms_bm): |
| 0 | 6933 _span(span), |
| 6934 _verification_bm(verification_bm), | |
|
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6935 _cms_bm(cms_bm) |
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6936 { |
| 0 | 6937 assert(_ref_processor == NULL, "deliberately left NULL"); |
| 6938 assert(_verification_bm->covers(_span), "_verification_bm/_span mismatch"); | |
| 6939 } | |
| 6940 | |
|
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6941 void MarkRefsIntoVerifyClosure::do_oop(oop obj) { |
| 0 | 6942 // if p points into _span, then mark corresponding bit in _markBitMap |
|
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6943 assert(obj->is_oop(), "expected an oop"); |
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6944 HeapWord* addr = (HeapWord*)obj; |
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6945 if (_span.contains(addr)) { |
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6946 _verification_bm->mark(addr); |
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6947 if (!_cms_bm->isMarked(addr)) { |
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6948 oop(addr)->print(); |
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6949 gclog_or_tty->print_cr(" (" INTPTR_FORMAT " should have been marked)", addr); |
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6950 fatal("... aborting"); |
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6951 } |
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6952 } |
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6953 } |
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6954 |
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6955 void MarkRefsIntoVerifyClosure::do_oop(oop* p) { MarkRefsIntoVerifyClosure::do_oop_work(p); } |
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6956 void MarkRefsIntoVerifyClosure::do_oop(narrowOop* p) { MarkRefsIntoVerifyClosure::do_oop_work(p); } |
| 0 | 6957 |
| 6958 ////////////////////////////////////////////////// | |
| 6959 // MarkRefsIntoAndScanClosure | |
| 6960 ////////////////////////////////////////////////// | |
| 6961 | |
| 6962 MarkRefsIntoAndScanClosure::MarkRefsIntoAndScanClosure(MemRegion span, | |
| 6963 ReferenceProcessor* rp, | |
| 6964 CMSBitMap* bit_map, | |
| 6965 CMSBitMap* mod_union_table, | |
| 6966 CMSMarkStack* mark_stack, | |
| 6967 CMSCollector* collector, | |
| 6968 bool should_yield, | |
| 6969 bool concurrent_precleaning): | |
| 6970 _collector(collector), | |
| 6971 _span(span), | |
| 6972 _bit_map(bit_map), | |
| 6973 _mark_stack(mark_stack), | |
| 6974 _pushAndMarkClosure(collector, span, rp, bit_map, mod_union_table, | |
|
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6975 mark_stack, concurrent_precleaning), |
| 0 | 6976 _yield(should_yield), |
| 6977 _concurrent_precleaning(concurrent_precleaning), | |
| 6978 _freelistLock(NULL) | |
| 6979 { | |
| 6980 _ref_processor = rp; | |
| 6981 assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL"); | |
| 6982 } | |
| 6983 | |
| 6984 // This closure is used to mark refs into the CMS generation at the | |
| 6985 // second (final) checkpoint, and to scan and transitively follow | |
| 6986 // the unmarked oops. It is also used during the concurrent precleaning | |
| 6987 // phase while scanning objects on dirty cards in the CMS generation. | |
| 6988 // The marks are made in the marking bit map and the marking stack is | |
| 6989 // used for keeping the (newly) grey objects during the scan. | |
| 6990 // The parallel version (Par_...) appears further below. | |
|
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6991 void MarkRefsIntoAndScanClosure::do_oop(oop obj) { |
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6992 if (obj != NULL) { |
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6993 assert(obj->is_oop(), "expected an oop"); |
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6994 HeapWord* addr = (HeapWord*)obj; |
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6995 assert(_mark_stack->isEmpty(), "pre-condition (eager drainage)"); |
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6996 assert(_collector->overflow_list_is_empty(), |
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6997 "overflow list should be empty"); |
| 0 | 6998 if (_span.contains(addr) && |
| 6999 !_bit_map->isMarked(addr)) { | |
| 7000 // mark bit map (object is now grey) | |
| 7001 _bit_map->mark(addr); | |
| 7002 // push on marking stack (stack should be empty), and drain the | |
| 7003 // stack by applying this closure to the oops in the oops popped | |
| 7004 // from the stack (i.e. blacken the grey objects) | |
|
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7005 bool res = _mark_stack->push(obj); |
| 0 | 7006 assert(res, "Should have space to push on empty stack"); |
| 7007 do { | |
| 7008 oop new_oop = _mark_stack->pop(); | |
| 7009 assert(new_oop != NULL && new_oop->is_oop(), "Expected an oop"); | |
| 7010 assert(_bit_map->isMarked((HeapWord*)new_oop), | |
| 7011 "only grey objects on this stack"); | |
| 7012 // iterate over the oops in this oop, marking and pushing | |
| 7013 // the ones in CMS heap (i.e. in _span). | |
| 7014 new_oop->oop_iterate(&_pushAndMarkClosure); | |
| 7015 // check if it's time to yield | |
| 7016 do_yield_check(); | |
| 7017 } while (!_mark_stack->isEmpty() || | |
| 7018 (!_concurrent_precleaning && take_from_overflow_list())); | |
| 7019 // if marking stack is empty, and we are not doing this | |
| 7020 // during precleaning, then check the overflow list | |
| 7021 } | |
| 7022 assert(_mark_stack->isEmpty(), "post-condition (eager drainage)"); | |
| 7023 assert(_collector->overflow_list_is_empty(), | |
| 7024 "overflow list was drained above"); | |
| 7025 // We could restore evacuated mark words, if any, used for | |
| 7026 // overflow list links here because the overflow list is | |
| 7027 // provably empty here. That would reduce the maximum | |
| 7028 // size requirements for preserved_{oop,mark}_stack. | |
| 7029 // But we'll just postpone it until we are all done | |
| 7030 // so we can just stream through. | |
| 7031 if (!_concurrent_precleaning && CMSOverflowEarlyRestoration) { | |
| 7032 _collector->restore_preserved_marks_if_any(); | |
| 7033 assert(_collector->no_preserved_marks(), "No preserved marks"); | |
| 7034 } | |
| 7035 assert(!CMSOverflowEarlyRestoration || _collector->no_preserved_marks(), | |
| 7036 "All preserved marks should have been restored above"); | |
| 7037 } | |
| 7038 } | |
| 7039 | |
|
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7040 void MarkRefsIntoAndScanClosure::do_oop(oop* p) { MarkRefsIntoAndScanClosure::do_oop_work(p); } |
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7041 void MarkRefsIntoAndScanClosure::do_oop(narrowOop* p) { MarkRefsIntoAndScanClosure::do_oop_work(p); } |
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7042 |
| 0 | 7043 void MarkRefsIntoAndScanClosure::do_yield_work() { |
| 7044 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 7045 "CMS thread should hold CMS token"); | |
| 7046 assert_lock_strong(_freelistLock); | |
| 7047 assert_lock_strong(_bit_map->lock()); | |
| 7048 // relinquish the free_list_lock and bitMaplock() | |
| 7049 _bit_map->lock()->unlock(); | |
| 7050 _freelistLock->unlock(); | |
| 7051 ConcurrentMarkSweepThread::desynchronize(true); | |
| 7052 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7053 _collector->stopTimer(); | |
| 7054 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 7055 if (PrintCMSStatistics != 0) { | |
| 7056 _collector->incrementYields(); | |
| 7057 } | |
| 7058 _collector->icms_wait(); | |
| 7059 | |
| 7060 // See the comment in coordinator_yield() | |
|
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7061 for (unsigned i = 0; |
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7062 i < CMSYieldSleepCount && |
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7063 ConcurrentMarkSweepThread::should_yield() && |
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7064 !CMSCollector::foregroundGCIsActive(); |
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7065 ++i) { |
| 0 | 7066 os::sleep(Thread::current(), 1, false); |
| 7067 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7068 } | |
| 7069 | |
| 7070 ConcurrentMarkSweepThread::synchronize(true); | |
| 7071 _freelistLock->lock_without_safepoint_check(); | |
| 7072 _bit_map->lock()->lock_without_safepoint_check(); | |
| 7073 _collector->startTimer(); | |
| 7074 } | |
| 7075 | |
| 7076 /////////////////////////////////////////////////////////// | |
| 7077 // Par_MarkRefsIntoAndScanClosure: a parallel version of | |
| 7078 // MarkRefsIntoAndScanClosure | |
| 7079 /////////////////////////////////////////////////////////// | |
| 7080 Par_MarkRefsIntoAndScanClosure::Par_MarkRefsIntoAndScanClosure( | |
| 7081 CMSCollector* collector, MemRegion span, ReferenceProcessor* rp, | |
|
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7082 CMSBitMap* bit_map, OopTaskQueue* work_queue): |
| 0 | 7083 _span(span), |
| 7084 _bit_map(bit_map), | |
| 7085 _work_queue(work_queue), | |
| 7086 _low_water_mark(MIN2((uint)(work_queue->max_elems()/4), | |
| 7087 (uint)(CMSWorkQueueDrainThreshold * ParallelGCThreads))), | |
|
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7088 _par_pushAndMarkClosure(collector, span, rp, bit_map, work_queue) |
| 0 | 7089 { |
| 7090 _ref_processor = rp; | |
| 7091 assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL"); | |
| 7092 } | |
| 7093 | |
| 7094 // This closure is used to mark refs into the CMS generation at the | |
| 7095 // second (final) checkpoint, and to scan and transitively follow | |
| 7096 // the unmarked oops. The marks are made in the marking bit map and | |
| 7097 // the work_queue is used for keeping the (newly) grey objects during | |
| 7098 // the scan phase whence they are also available for stealing by parallel | |
| 7099 // threads. Since the marking bit map is shared, updates are | |
| 7100 // synchronized (via CAS). | |
|
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7101 void Par_MarkRefsIntoAndScanClosure::do_oop(oop obj) { |
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7102 if (obj != NULL) { |
| 0 | 7103 // Ignore mark word because this could be an already marked oop |
| 7104 // that may be chained at the end of the overflow list. | |
|
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7105 assert(obj->is_oop(true), "expected an oop"); |
|
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7106 HeapWord* addr = (HeapWord*)obj; |
| 0 | 7107 if (_span.contains(addr) && |
| 7108 !_bit_map->isMarked(addr)) { | |
| 7109 // mark bit map (object will become grey): | |
| 7110 // It is possible for several threads to be | |
| 7111 // trying to "claim" this object concurrently; | |
| 7112 // the unique thread that succeeds in marking the | |
| 7113 // object first will do the subsequent push on | |
| 7114 // to the work queue (or overflow list). | |
| 7115 if (_bit_map->par_mark(addr)) { | |
| 7116 // push on work_queue (which may not be empty), and trim the | |
| 7117 // queue to an appropriate length by applying this closure to | |
| 7118 // the oops in the oops popped from the stack (i.e. blacken the | |
| 7119 // grey objects) | |
|
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7120 bool res = _work_queue->push(obj); |
| 0 | 7121 assert(res, "Low water mark should be less than capacity?"); |
| 7122 trim_queue(_low_water_mark); | |
| 7123 } // Else, another thread claimed the object | |
| 7124 } | |
| 7125 } | |
| 7126 } | |
| 7127 | |
|
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7128 void Par_MarkRefsIntoAndScanClosure::do_oop(oop* p) { Par_MarkRefsIntoAndScanClosure::do_oop_work(p); } |
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7129 void Par_MarkRefsIntoAndScanClosure::do_oop(narrowOop* p) { Par_MarkRefsIntoAndScanClosure::do_oop_work(p); } |
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7130 |
| 0 | 7131 // This closure is used to rescan the marked objects on the dirty cards |
| 7132 // in the mod union table and the card table proper. | |
| 7133 size_t ScanMarkedObjectsAgainCarefullyClosure::do_object_careful_m( | |
| 7134 oop p, MemRegion mr) { | |
| 7135 | |
| 7136 size_t size = 0; | |
| 7137 HeapWord* addr = (HeapWord*)p; | |
| 7138 DEBUG_ONLY(_collector->verify_work_stacks_empty();) | |
| 7139 assert(_span.contains(addr), "we are scanning the CMS generation"); | |
| 7140 // check if it's time to yield | |
| 7141 if (do_yield_check()) { | |
| 7142 // We yielded for some foreground stop-world work, | |
| 7143 // and we have been asked to abort this ongoing preclean cycle. | |
| 7144 return 0; | |
| 7145 } | |
| 7146 if (_bitMap->isMarked(addr)) { | |
| 7147 // it's marked; is it potentially uninitialized? | |
| 187 | 7148 if (p->klass_or_null() != NULL) { |
| 0 | 7149 // an initialized object; ignore mark word in verification below |
| 7150 // since we are running concurrent with mutators | |
| 7151 assert(p->is_oop(true), "should be an oop"); | |
| 7152 if (p->is_objArray()) { | |
| 7153 // objArrays are precisely marked; restrict scanning | |
| 7154 // to dirty cards only. | |
| 187 | 7155 size = CompactibleFreeListSpace::adjustObjectSize( |
| 7156 p->oop_iterate(_scanningClosure, mr)); | |
| 0 | 7157 } else { |
| 7158 // A non-array may have been imprecisely marked; we need | |
| 7159 // to scan object in its entirety. | |
| 7160 size = CompactibleFreeListSpace::adjustObjectSize( | |
| 7161 p->oop_iterate(_scanningClosure)); | |
| 7162 } | |
| 9152 | 7163 #ifdef ASSERT |
| 0 | 7164 size_t direct_size = |
| 7165 CompactibleFreeListSpace::adjustObjectSize(p->size()); | |
| 7166 assert(size == direct_size, "Inconsistency in size"); | |
| 7167 assert(size >= 3, "Necessary for Printezis marks to work"); | |
| 7168 if (!_bitMap->isMarked(addr+1)) { | |
| 7169 _bitMap->verifyNoOneBitsInRange(addr+2, addr+size); | |
| 7170 } else { | |
| 7171 _bitMap->verifyNoOneBitsInRange(addr+2, addr+size-1); | |
| 7172 assert(_bitMap->isMarked(addr+size-1), | |
| 7173 "inconsistent Printezis mark"); | |
| 7174 } | |
| 9152 | 7175 #endif // ASSERT |
| 0 | 7176 } else { |
| 14309 | 7177 // An uninitialized object. |
| 0 | 7178 assert(_bitMap->isMarked(addr+1), "missing Printezis mark?"); |
| 7179 HeapWord* nextOneAddr = _bitMap->getNextMarkedWordAddress(addr + 2); | |
| 7180 size = pointer_delta(nextOneAddr + 1, addr); | |
| 7181 assert(size == CompactibleFreeListSpace::adjustObjectSize(size), | |
| 7182 "alignment problem"); | |
| 7183 // Note that pre-cleaning needn't redirty the card. OopDesc::set_klass() | |
| 7184 // will dirty the card when the klass pointer is installed in the | |
| 14309 | 7185 // object (signaling the completion of initialization). |
| 0 | 7186 } |
| 7187 } else { | |
| 7188 // Either a not yet marked object or an uninitialized object | |
|
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7189 if (p->klass_or_null() == NULL) { |
| 0 | 7190 // An uninitialized object, skip to the next card, since |
| 7191 // we may not be able to read its P-bits yet. | |
| 7192 assert(size == 0, "Initial value"); | |
| 7193 } else { | |
| 7194 // An object not (yet) reached by marking: we merely need to | |
| 7195 // compute its size so as to go look at the next block. | |
| 7196 assert(p->is_oop(true), "should be an oop"); | |
| 7197 size = CompactibleFreeListSpace::adjustObjectSize(p->size()); | |
| 7198 } | |
| 7199 } | |
| 7200 DEBUG_ONLY(_collector->verify_work_stacks_empty();) | |
| 7201 return size; | |
| 7202 } | |
| 7203 | |
| 7204 void ScanMarkedObjectsAgainCarefullyClosure::do_yield_work() { | |
| 7205 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 7206 "CMS thread should hold CMS token"); | |
| 7207 assert_lock_strong(_freelistLock); | |
| 7208 assert_lock_strong(_bitMap->lock()); | |
| 7209 // relinquish the free_list_lock and bitMaplock() | |
| 7210 _bitMap->lock()->unlock(); | |
| 7211 _freelistLock->unlock(); | |
| 7212 ConcurrentMarkSweepThread::desynchronize(true); | |
| 7213 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7214 _collector->stopTimer(); | |
| 7215 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 7216 if (PrintCMSStatistics != 0) { | |
| 7217 _collector->incrementYields(); | |
| 7218 } | |
| 7219 _collector->icms_wait(); | |
| 7220 | |
| 7221 // See the comment in coordinator_yield() | |
| 7222 for (unsigned i = 0; i < CMSYieldSleepCount && | |
|
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7223 ConcurrentMarkSweepThread::should_yield() && |
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7224 !CMSCollector::foregroundGCIsActive(); ++i) { |
| 0 | 7225 os::sleep(Thread::current(), 1, false); |
| 7226 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7227 } | |
| 7228 | |
| 7229 ConcurrentMarkSweepThread::synchronize(true); | |
| 7230 _freelistLock->lock_without_safepoint_check(); | |
| 7231 _bitMap->lock()->lock_without_safepoint_check(); | |
| 7232 _collector->startTimer(); | |
| 7233 } | |
| 7234 | |
| 7235 | |
| 7236 ////////////////////////////////////////////////////////////////// | |
| 7237 // SurvivorSpacePrecleanClosure | |
| 7238 ////////////////////////////////////////////////////////////////// | |
| 7239 // This (single-threaded) closure is used to preclean the oops in | |
| 7240 // the survivor spaces. | |
| 7241 size_t SurvivorSpacePrecleanClosure::do_object_careful(oop p) { | |
| 7242 | |
| 7243 HeapWord* addr = (HeapWord*)p; | |
| 7244 DEBUG_ONLY(_collector->verify_work_stacks_empty();) | |
| 7245 assert(!_span.contains(addr), "we are scanning the survivor spaces"); | |
| 187 | 7246 assert(p->klass_or_null() != NULL, "object should be initializd"); |
| 0 | 7247 // an initialized object; ignore mark word in verification below |
| 7248 // since we are running concurrent with mutators | |
| 7249 assert(p->is_oop(true), "should be an oop"); | |
| 7250 // Note that we do not yield while we iterate over | |
| 7251 // the interior oops of p, pushing the relevant ones | |
| 7252 // on our marking stack. | |
| 7253 size_t size = p->oop_iterate(_scanning_closure); | |
| 7254 do_yield_check(); | |
| 7255 // Observe that below, we do not abandon the preclean | |
| 7256 // phase as soon as we should; rather we empty the | |
| 7257 // marking stack before returning. This is to satisfy | |
| 7258 // some existing assertions. In general, it may be a | |
| 7259 // good idea to abort immediately and complete the marking | |
| 7260 // from the grey objects at a later time. | |
| 7261 while (!_mark_stack->isEmpty()) { | |
| 7262 oop new_oop = _mark_stack->pop(); | |
| 7263 assert(new_oop != NULL && new_oop->is_oop(), "Expected an oop"); | |
| 7264 assert(_bit_map->isMarked((HeapWord*)new_oop), | |
| 7265 "only grey objects on this stack"); | |
| 7266 // iterate over the oops in this oop, marking and pushing | |
| 7267 // the ones in CMS heap (i.e. in _span). | |
| 7268 new_oop->oop_iterate(_scanning_closure); | |
| 7269 // check if it's time to yield | |
| 7270 do_yield_check(); | |
| 7271 } | |
| 7272 unsigned int after_count = | |
| 7273 GenCollectedHeap::heap()->total_collections(); | |
| 7274 bool abort = (_before_count != after_count) || | |
| 7275 _collector->should_abort_preclean(); | |
| 7276 return abort ? 0 : size; | |
| 7277 } | |
| 7278 | |
| 7279 void SurvivorSpacePrecleanClosure::do_yield_work() { | |
| 7280 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 7281 "CMS thread should hold CMS token"); | |
| 7282 assert_lock_strong(_bit_map->lock()); | |
| 7283 // Relinquish the bit map lock | |
| 7284 _bit_map->lock()->unlock(); | |
| 7285 ConcurrentMarkSweepThread::desynchronize(true); | |
| 7286 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7287 _collector->stopTimer(); | |
| 7288 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 7289 if (PrintCMSStatistics != 0) { | |
| 7290 _collector->incrementYields(); | |
| 7291 } | |
| 7292 _collector->icms_wait(); | |
| 7293 | |
| 7294 // See the comment in coordinator_yield() | |
| 7295 for (unsigned i = 0; i < CMSYieldSleepCount && | |
| 7296 ConcurrentMarkSweepThread::should_yield() && | |
| 7297 !CMSCollector::foregroundGCIsActive(); ++i) { | |
| 7298 os::sleep(Thread::current(), 1, false); | |
| 7299 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7300 } | |
| 7301 | |
| 7302 ConcurrentMarkSweepThread::synchronize(true); | |
| 7303 _bit_map->lock()->lock_without_safepoint_check(); | |
| 7304 _collector->startTimer(); | |
| 7305 } | |
| 7306 | |
| 7307 // This closure is used to rescan the marked objects on the dirty cards | |
| 7308 // in the mod union table and the card table proper. In the parallel | |
| 7309 // case, although the bitMap is shared, we do a single read so the | |
| 7310 // isMarked() query is "safe". | |
| 7311 bool ScanMarkedObjectsAgainClosure::do_object_bm(oop p, MemRegion mr) { | |
| 7312 // Ignore mark word because we are running concurrent with mutators | |
| 7313 assert(p->is_oop_or_null(true), "expected an oop or null"); | |
| 7314 HeapWord* addr = (HeapWord*)p; | |
| 7315 assert(_span.contains(addr), "we are scanning the CMS generation"); | |
| 7316 bool is_obj_array = false; | |
| 9152 | 7317 #ifdef ASSERT |
| 0 | 7318 if (!_parallel) { |
| 7319 assert(_mark_stack->isEmpty(), "pre-condition (eager drainage)"); | |
| 7320 assert(_collector->overflow_list_is_empty(), | |
| 7321 "overflow list should be empty"); | |
| 7322 | |
| 7323 } | |
| 9152 | 7324 #endif // ASSERT |
| 0 | 7325 if (_bit_map->isMarked(addr)) { |
| 7326 // Obj arrays are precisely marked, non-arrays are not; | |
| 7327 // so we scan objArrays precisely and non-arrays in their | |
| 7328 // entirety. | |
| 7329 if (p->is_objArray()) { | |
| 7330 is_obj_array = true; | |
| 7331 if (_parallel) { | |
| 7332 p->oop_iterate(_par_scan_closure, mr); | |
| 7333 } else { | |
| 7334 p->oop_iterate(_scan_closure, mr); | |
| 7335 } | |
| 7336 } else { | |
| 7337 if (_parallel) { | |
| 7338 p->oop_iterate(_par_scan_closure); | |
| 7339 } else { | |
| 7340 p->oop_iterate(_scan_closure); | |
| 7341 } | |
| 7342 } | |
| 7343 } | |
| 9152 | 7344 #ifdef ASSERT |
| 0 | 7345 if (!_parallel) { |
| 7346 assert(_mark_stack->isEmpty(), "post-condition (eager drainage)"); | |
| 7347 assert(_collector->overflow_list_is_empty(), | |
| 7348 "overflow list should be empty"); | |
| 7349 | |
| 7350 } | |
| 9152 | 7351 #endif // ASSERT |
| 0 | 7352 return is_obj_array; |
| 7353 } | |
| 7354 | |
| 7355 MarkFromRootsClosure::MarkFromRootsClosure(CMSCollector* collector, | |
| 7356 MemRegion span, | |
| 7357 CMSBitMap* bitMap, CMSMarkStack* markStack, | |
| 7358 bool should_yield, bool verifying): | |
| 7359 _collector(collector), | |
| 7360 _span(span), | |
| 7361 _bitMap(bitMap), | |
| 7362 _mut(&collector->_modUnionTable), | |
| 7363 _markStack(markStack), | |
| 7364 _yield(should_yield), | |
| 7365 _skipBits(0) | |
| 7366 { | |
| 7367 assert(_markStack->isEmpty(), "stack should be empty"); | |
| 7368 _finger = _bitMap->startWord(); | |
| 7369 _threshold = _finger; | |
| 7370 assert(_collector->_restart_addr == NULL, "Sanity check"); | |
| 7371 assert(_span.contains(_finger), "Out of bounds _finger?"); | |
| 7372 DEBUG_ONLY(_verifying = verifying;) | |
| 7373 } | |
| 7374 | |
| 7375 void MarkFromRootsClosure::reset(HeapWord* addr) { | |
| 7376 assert(_markStack->isEmpty(), "would cause duplicates on stack"); | |
| 7377 assert(_span.contains(addr), "Out of bounds _finger?"); | |
| 7378 _finger = addr; | |
| 7379 _threshold = (HeapWord*)round_to( | |
| 7380 (intptr_t)_finger, CardTableModRefBS::card_size); | |
| 7381 } | |
| 7382 | |
| 7383 // Should revisit to see if this should be restructured for | |
| 7384 // greater efficiency. | |
|
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7385 bool MarkFromRootsClosure::do_bit(size_t offset) { |
| 0 | 7386 if (_skipBits > 0) { |
| 7387 _skipBits--; | |
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7388 return true; |
| 0 | 7389 } |
| 7390 // convert offset into a HeapWord* | |
| 7391 HeapWord* addr = _bitMap->startWord() + offset; | |
| 7392 assert(_bitMap->endWord() && addr < _bitMap->endWord(), | |
| 7393 "address out of range"); | |
| 7394 assert(_bitMap->isMarked(addr), "tautology"); | |
| 7395 if (_bitMap->isMarked(addr+1)) { | |
| 7396 // this is an allocated but not yet initialized object | |
| 7397 assert(_skipBits == 0, "tautology"); | |
| 7398 _skipBits = 2; // skip next two marked bits ("Printezis-marks") | |
| 7399 oop p = oop(addr); | |
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7400 if (p->klass_or_null() == NULL) { |
| 0 | 7401 DEBUG_ONLY(if (!_verifying) {) |
| 7402 // We re-dirty the cards on which this object lies and increase | |
| 7403 // the _threshold so that we'll come back to scan this object | |
| 7404 // during the preclean or remark phase. (CMSCleanOnEnter) | |
| 7405 if (CMSCleanOnEnter) { | |
| 7406 size_t sz = _collector->block_size_using_printezis_bits(addr); | |
| 7407 HeapWord* end_card_addr = (HeapWord*)round_to( | |
| 7408 (intptr_t)(addr+sz), CardTableModRefBS::card_size); | |
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7409 MemRegion redirty_range = MemRegion(addr, end_card_addr); |
| 0 | 7410 assert(!redirty_range.is_empty(), "Arithmetical tautology"); |
| 7411 // Bump _threshold to end_card_addr; note that | |
| 7412 // _threshold cannot possibly exceed end_card_addr, anyhow. | |
| 7413 // This prevents future clearing of the card as the scan proceeds | |
| 7414 // to the right. | |
| 7415 assert(_threshold <= end_card_addr, | |
| 7416 "Because we are just scanning into this object"); | |
| 7417 if (_threshold < end_card_addr) { | |
| 7418 _threshold = end_card_addr; | |
| 7419 } | |
| 187 | 7420 if (p->klass_or_null() != NULL) { |
| 0 | 7421 // Redirty the range of cards... |
| 7422 _mut->mark_range(redirty_range); | |
| 7423 } // ...else the setting of klass will dirty the card anyway. | |
| 7424 } | |
| 7425 DEBUG_ONLY(}) | |
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7426 return true; |
| 0 | 7427 } |
| 7428 } | |
| 7429 scanOopsInOop(addr); | |
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7430 return true; |
| 0 | 7431 } |
| 7432 | |
| 7433 // We take a break if we've been at this for a while, | |
| 7434 // so as to avoid monopolizing the locks involved. | |
| 7435 void MarkFromRootsClosure::do_yield_work() { | |
| 7436 // First give up the locks, then yield, then re-lock | |
| 7437 // We should probably use a constructor/destructor idiom to | |
| 7438 // do this unlock/lock or modify the MutexUnlocker class to | |
| 7439 // serve our purpose. XXX | |
| 7440 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 7441 "CMS thread should hold CMS token"); | |
| 7442 assert_lock_strong(_bitMap->lock()); | |
| 7443 _bitMap->lock()->unlock(); | |
| 7444 ConcurrentMarkSweepThread::desynchronize(true); | |
| 7445 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7446 _collector->stopTimer(); | |
| 7447 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 7448 if (PrintCMSStatistics != 0) { | |
| 7449 _collector->incrementYields(); | |
| 7450 } | |
| 7451 _collector->icms_wait(); | |
| 7452 | |
| 7453 // See the comment in coordinator_yield() | |
| 7454 for (unsigned i = 0; i < CMSYieldSleepCount && | |
| 7455 ConcurrentMarkSweepThread::should_yield() && | |
| 7456 !CMSCollector::foregroundGCIsActive(); ++i) { | |
| 7457 os::sleep(Thread::current(), 1, false); | |
| 7458 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7459 } | |
| 7460 | |
| 7461 ConcurrentMarkSweepThread::synchronize(true); | |
| 7462 _bitMap->lock()->lock_without_safepoint_check(); | |
| 7463 _collector->startTimer(); | |
| 7464 } | |
| 7465 | |
| 7466 void MarkFromRootsClosure::scanOopsInOop(HeapWord* ptr) { | |
| 7467 assert(_bitMap->isMarked(ptr), "expected bit to be set"); | |
| 7468 assert(_markStack->isEmpty(), | |
| 7469 "should drain stack to limit stack usage"); | |
| 7470 // convert ptr to an oop preparatory to scanning | |
|
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7471 oop obj = oop(ptr); |
| 0 | 7472 // Ignore mark word in verification below, since we |
| 7473 // may be running concurrent with mutators. | |
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7474 assert(obj->is_oop(true), "should be an oop"); |
| 0 | 7475 assert(_finger <= ptr, "_finger runneth ahead"); |
| 7476 // advance the finger to right end of this object | |
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7477 _finger = ptr + obj->size(); |
| 0 | 7478 assert(_finger > ptr, "we just incremented it above"); |
| 7479 // On large heaps, it may take us some time to get through | |
| 7480 // the marking phase (especially if running iCMS). During | |
| 7481 // this time it's possible that a lot of mutations have | |
| 7482 // accumulated in the card table and the mod union table -- | |
| 7483 // these mutation records are redundant until we have | |
| 7484 // actually traced into the corresponding card. | |
| 7485 // Here, we check whether advancing the finger would make | |
| 7486 // us cross into a new card, and if so clear corresponding | |
| 7487 // cards in the MUT (preclean them in the card-table in the | |
| 7488 // future). | |
| 7489 | |
| 7490 DEBUG_ONLY(if (!_verifying) {) | |
| 7491 // The clean-on-enter optimization is disabled by default, | |
| 7492 // until we fix 6178663. | |
| 7493 if (CMSCleanOnEnter && (_finger > _threshold)) { | |
| 7494 // [_threshold, _finger) represents the interval | |
| 7495 // of cards to be cleared in MUT (or precleaned in card table). | |
| 7496 // The set of cards to be cleared is all those that overlap | |
| 7497 // with the interval [_threshold, _finger); note that | |
| 7498 // _threshold is always kept card-aligned but _finger isn't | |
| 7499 // always card-aligned. | |
| 7500 HeapWord* old_threshold = _threshold; | |
| 7501 assert(old_threshold == (HeapWord*)round_to( | |
| 7502 (intptr_t)old_threshold, CardTableModRefBS::card_size), | |
| 7503 "_threshold should always be card-aligned"); | |
| 7504 _threshold = (HeapWord*)round_to( | |
| 7505 (intptr_t)_finger, CardTableModRefBS::card_size); | |
| 7506 MemRegion mr(old_threshold, _threshold); | |
| 7507 assert(!mr.is_empty(), "Control point invariant"); | |
| 7508 assert(_span.contains(mr), "Should clear within span"); | |
| 7509 _mut->clear_range(mr); | |
| 7510 } | |
| 7511 DEBUG_ONLY(}) | |
| 7512 // Note: the finger doesn't advance while we drain | |
| 7513 // the stack below. | |
| 7514 PushOrMarkClosure pushOrMarkClosure(_collector, | |
| 7515 _span, _bitMap, _markStack, | |
| 7516 _finger, this); | |
|
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7517 bool res = _markStack->push(obj); |
| 0 | 7518 assert(res, "Empty non-zero size stack should have space for single push"); |
| 7519 while (!_markStack->isEmpty()) { | |
| 7520 oop new_oop = _markStack->pop(); | |
| 7521 // Skip verifying header mark word below because we are | |
| 7522 // running concurrent with mutators. | |
| 7523 assert(new_oop->is_oop(true), "Oops! expected to pop an oop"); | |
| 7524 // now scan this oop's oops | |
| 7525 new_oop->oop_iterate(&pushOrMarkClosure); | |
| 7526 do_yield_check(); | |
| 7527 } | |
| 7528 assert(_markStack->isEmpty(), "tautology, emphasizing post-condition"); | |
| 7529 } | |
| 7530 | |
| 7531 Par_MarkFromRootsClosure::Par_MarkFromRootsClosure(CMSConcMarkingTask* task, | |
| 7532 CMSCollector* collector, MemRegion span, | |
| 7533 CMSBitMap* bit_map, | |
| 7534 OopTaskQueue* work_queue, | |
| 7535 CMSMarkStack* overflow_stack, | |
| 7536 bool should_yield): | |
| 7537 _collector(collector), | |
| 7538 _whole_span(collector->_span), | |
| 7539 _span(span), | |
| 7540 _bit_map(bit_map), | |
| 7541 _mut(&collector->_modUnionTable), | |
| 7542 _work_queue(work_queue), | |
| 7543 _overflow_stack(overflow_stack), | |
| 7544 _yield(should_yield), | |
| 7545 _skip_bits(0), | |
| 7546 _task(task) | |
| 7547 { | |
| 7548 assert(_work_queue->size() == 0, "work_queue should be empty"); | |
| 7549 _finger = span.start(); | |
| 7550 _threshold = _finger; // XXX Defer clear-on-enter optimization for now | |
| 7551 assert(_span.contains(_finger), "Out of bounds _finger?"); | |
| 7552 } | |
| 7553 | |
| 7554 // Should revisit to see if this should be restructured for | |
| 7555 // greater efficiency. | |
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7556 bool Par_MarkFromRootsClosure::do_bit(size_t offset) { |
| 0 | 7557 if (_skip_bits > 0) { |
| 7558 _skip_bits--; | |
|
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7559 return true; |
| 0 | 7560 } |
| 7561 // convert offset into a HeapWord* | |
| 7562 HeapWord* addr = _bit_map->startWord() + offset; | |
| 7563 assert(_bit_map->endWord() && addr < _bit_map->endWord(), | |
| 7564 "address out of range"); | |
| 7565 assert(_bit_map->isMarked(addr), "tautology"); | |
| 7566 if (_bit_map->isMarked(addr+1)) { | |
| 7567 // this is an allocated object that might not yet be initialized | |
| 7568 assert(_skip_bits == 0, "tautology"); | |
| 7569 _skip_bits = 2; // skip next two marked bits ("Printezis-marks") | |
| 7570 oop p = oop(addr); | |
|
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7571 if (p->klass_or_null() == NULL) { |
| 0 | 7572 // in the case of Clean-on-Enter optimization, redirty card |
| 7573 // and avoid clearing card by increasing the threshold. | |
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7574 return true; |
| 0 | 7575 } |
| 7576 } | |
| 7577 scan_oops_in_oop(addr); | |
|
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7578 return true; |
| 0 | 7579 } |
| 7580 | |
| 7581 void Par_MarkFromRootsClosure::scan_oops_in_oop(HeapWord* ptr) { | |
| 7582 assert(_bit_map->isMarked(ptr), "expected bit to be set"); | |
| 7583 // Should we assert that our work queue is empty or | |
| 7584 // below some drain limit? | |
| 7585 assert(_work_queue->size() == 0, | |
| 7586 "should drain stack to limit stack usage"); | |
| 7587 // convert ptr to an oop preparatory to scanning | |
|
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7588 oop obj = oop(ptr); |
| 0 | 7589 // Ignore mark word in verification below, since we |
| 7590 // may be running concurrent with mutators. | |
|
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7591 assert(obj->is_oop(true), "should be an oop"); |
| 0 | 7592 assert(_finger <= ptr, "_finger runneth ahead"); |
| 7593 // advance the finger to right end of this object | |
|
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7594 _finger = ptr + obj->size(); |
| 0 | 7595 assert(_finger > ptr, "we just incremented it above"); |
| 7596 // On large heaps, it may take us some time to get through | |
| 7597 // the marking phase (especially if running iCMS). During | |
| 7598 // this time it's possible that a lot of mutations have | |
| 7599 // accumulated in the card table and the mod union table -- | |
| 7600 // these mutation records are redundant until we have | |
| 7601 // actually traced into the corresponding card. | |
| 7602 // Here, we check whether advancing the finger would make | |
| 7603 // us cross into a new card, and if so clear corresponding | |
| 7604 // cards in the MUT (preclean them in the card-table in the | |
| 7605 // future). | |
| 7606 | |
| 7607 // The clean-on-enter optimization is disabled by default, | |
| 7608 // until we fix 6178663. | |
| 7609 if (CMSCleanOnEnter && (_finger > _threshold)) { | |
| 7610 // [_threshold, _finger) represents the interval | |
| 7611 // of cards to be cleared in MUT (or precleaned in card table). | |
| 7612 // The set of cards to be cleared is all those that overlap | |
| 7613 // with the interval [_threshold, _finger); note that | |
| 7614 // _threshold is always kept card-aligned but _finger isn't | |
| 7615 // always card-aligned. | |
| 7616 HeapWord* old_threshold = _threshold; | |
| 7617 assert(old_threshold == (HeapWord*)round_to( | |
| 7618 (intptr_t)old_threshold, CardTableModRefBS::card_size), | |
| 7619 "_threshold should always be card-aligned"); | |
| 7620 _threshold = (HeapWord*)round_to( | |
| 7621 (intptr_t)_finger, CardTableModRefBS::card_size); | |
| 7622 MemRegion mr(old_threshold, _threshold); | |
| 7623 assert(!mr.is_empty(), "Control point invariant"); | |
| 7624 assert(_span.contains(mr), "Should clear within span"); // _whole_span ?? | |
| 7625 _mut->clear_range(mr); | |
| 7626 } | |
| 7627 | |
| 7628 // Note: the local finger doesn't advance while we drain | |
| 7629 // the stack below, but the global finger sure can and will. | |
| 7630 HeapWord** gfa = _task->global_finger_addr(); | |
| 7631 Par_PushOrMarkClosure pushOrMarkClosure(_collector, | |
| 7632 _span, _bit_map, | |
| 7633 _work_queue, | |
| 7634 _overflow_stack, | |
| 7635 _finger, | |
| 7636 gfa, this); | |
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7637 bool res = _work_queue->push(obj); // overflow could occur here |
| 0 | 7638 assert(res, "Will hold once we use workqueues"); |
| 7639 while (true) { | |
| 7640 oop new_oop; | |
| 7641 if (!_work_queue->pop_local(new_oop)) { | |
| 7642 // We emptied our work_queue; check if there's stuff that can | |
| 7643 // be gotten from the overflow stack. | |
| 7644 if (CMSConcMarkingTask::get_work_from_overflow_stack( | |
| 7645 _overflow_stack, _work_queue)) { | |
| 7646 do_yield_check(); | |
| 7647 continue; | |
| 7648 } else { // done | |
| 7649 break; | |
| 7650 } | |
| 7651 } | |
| 7652 // Skip verifying header mark word below because we are | |
| 7653 // running concurrent with mutators. | |
| 7654 assert(new_oop->is_oop(true), "Oops! expected to pop an oop"); | |
| 7655 // now scan this oop's oops | |
| 7656 new_oop->oop_iterate(&pushOrMarkClosure); | |
| 7657 do_yield_check(); | |
| 7658 } | |
| 7659 assert(_work_queue->size() == 0, "tautology, emphasizing post-condition"); | |
| 7660 } | |
| 7661 | |
| 7662 // Yield in response to a request from VM Thread or | |
| 7663 // from mutators. | |
| 7664 void Par_MarkFromRootsClosure::do_yield_work() { | |
| 7665 assert(_task != NULL, "sanity"); | |
| 7666 _task->yield(); | |
| 7667 } | |
| 7668 | |
| 7669 // A variant of the above used for verifying CMS marking work. | |
| 7670 MarkFromRootsVerifyClosure::MarkFromRootsVerifyClosure(CMSCollector* collector, | |
| 7671 MemRegion span, | |
| 7672 CMSBitMap* verification_bm, CMSBitMap* cms_bm, | |
| 7673 CMSMarkStack* mark_stack): | |
| 7674 _collector(collector), | |
| 7675 _span(span), | |
| 7676 _verification_bm(verification_bm), | |
| 7677 _cms_bm(cms_bm), | |
| 7678 _mark_stack(mark_stack), | |
| 7679 _pam_verify_closure(collector, span, verification_bm, cms_bm, | |
| 7680 mark_stack) | |
| 7681 { | |
| 7682 assert(_mark_stack->isEmpty(), "stack should be empty"); | |
| 7683 _finger = _verification_bm->startWord(); | |
| 7684 assert(_collector->_restart_addr == NULL, "Sanity check"); | |
| 7685 assert(_span.contains(_finger), "Out of bounds _finger?"); | |
| 7686 } | |
| 7687 | |
| 7688 void MarkFromRootsVerifyClosure::reset(HeapWord* addr) { | |
| 7689 assert(_mark_stack->isEmpty(), "would cause duplicates on stack"); | |
| 7690 assert(_span.contains(addr), "Out of bounds _finger?"); | |
| 7691 _finger = addr; | |
| 7692 } | |
| 7693 | |
| 7694 // Should revisit to see if this should be restructured for | |
| 7695 // greater efficiency. | |
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7696 bool MarkFromRootsVerifyClosure::do_bit(size_t offset) { |
| 0 | 7697 // convert offset into a HeapWord* |
| 7698 HeapWord* addr = _verification_bm->startWord() + offset; | |
| 7699 assert(_verification_bm->endWord() && addr < _verification_bm->endWord(), | |
| 7700 "address out of range"); | |
| 7701 assert(_verification_bm->isMarked(addr), "tautology"); | |
| 7702 assert(_cms_bm->isMarked(addr), "tautology"); | |
| 7703 | |
| 7704 assert(_mark_stack->isEmpty(), | |
| 7705 "should drain stack to limit stack usage"); | |
| 7706 // convert addr to an oop preparatory to scanning | |
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7707 oop obj = oop(addr); |
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7708 assert(obj->is_oop(), "should be an oop"); |
| 0 | 7709 assert(_finger <= addr, "_finger runneth ahead"); |
| 7710 // advance the finger to right end of this object | |
|
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7711 _finger = addr + obj->size(); |
| 0 | 7712 assert(_finger > addr, "we just incremented it above"); |
| 7713 // Note: the finger doesn't advance while we drain | |
| 7714 // the stack below. | |
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7715 bool res = _mark_stack->push(obj); |
| 0 | 7716 assert(res, "Empty non-zero size stack should have space for single push"); |
| 7717 while (!_mark_stack->isEmpty()) { | |
| 7718 oop new_oop = _mark_stack->pop(); | |
| 7719 assert(new_oop->is_oop(), "Oops! expected to pop an oop"); | |
| 7720 // now scan this oop's oops | |
| 7721 new_oop->oop_iterate(&_pam_verify_closure); | |
| 7722 } | |
| 7723 assert(_mark_stack->isEmpty(), "tautology, emphasizing post-condition"); | |
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7724 return true; |
| 0 | 7725 } |
| 7726 | |
| 7727 PushAndMarkVerifyClosure::PushAndMarkVerifyClosure( | |
| 7728 CMSCollector* collector, MemRegion span, | |
| 7729 CMSBitMap* verification_bm, CMSBitMap* cms_bm, | |
| 7730 CMSMarkStack* mark_stack): | |
|
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7731 CMSOopClosure(collector->ref_processor()), |
| 0 | 7732 _collector(collector), |
| 7733 _span(span), | |
| 7734 _verification_bm(verification_bm), | |
| 7735 _cms_bm(cms_bm), | |
| 7736 _mark_stack(mark_stack) | |
| 7737 { } | |
| 7738 | |
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7739 void PushAndMarkVerifyClosure::do_oop(oop* p) { PushAndMarkVerifyClosure::do_oop_work(p); } |
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7740 void PushAndMarkVerifyClosure::do_oop(narrowOop* p) { PushAndMarkVerifyClosure::do_oop_work(p); } |
| 0 | 7741 |
| 7742 // Upon stack overflow, we discard (part of) the stack, | |
| 7743 // remembering the least address amongst those discarded | |
| 7744 // in CMSCollector's _restart_address. | |
| 7745 void PushAndMarkVerifyClosure::handle_stack_overflow(HeapWord* lost) { | |
| 7746 // Remember the least grey address discarded | |
| 7747 HeapWord* ra = (HeapWord*)_mark_stack->least_value(lost); | |
| 7748 _collector->lower_restart_addr(ra); | |
| 7749 _mark_stack->reset(); // discard stack contents | |
| 7750 _mark_stack->expand(); // expand the stack if possible | |
| 7751 } | |
| 7752 | |
|
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7753 void PushAndMarkVerifyClosure::do_oop(oop obj) { |
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7754 assert(obj->is_oop_or_null(), "expected an oop or NULL"); |
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7755 HeapWord* addr = (HeapWord*)obj; |
| 0 | 7756 if (_span.contains(addr) && !_verification_bm->isMarked(addr)) { |
| 7757 // Oop lies in _span and isn't yet grey or black | |
| 7758 _verification_bm->mark(addr); // now grey | |
| 7759 if (!_cms_bm->isMarked(addr)) { | |
| 7760 oop(addr)->print(); | |
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7761 gclog_or_tty->print_cr(" (" INTPTR_FORMAT " should have been marked)", |
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7762 addr); |
| 0 | 7763 fatal("... aborting"); |
| 7764 } | |
| 7765 | |
|
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7766 if (!_mark_stack->push(obj)) { // stack overflow |
| 0 | 7767 if (PrintCMSStatistics != 0) { |
| 7768 gclog_or_tty->print_cr("CMS marking stack overflow (benign) at " | |
| 7769 SIZE_FORMAT, _mark_stack->capacity()); | |
| 7770 } | |
| 7771 assert(_mark_stack->isFull(), "Else push should have succeeded"); | |
| 7772 handle_stack_overflow(addr); | |
| 7773 } | |
| 7774 // anything including and to the right of _finger | |
| 7775 // will be scanned as we iterate over the remainder of the | |
| 7776 // bit map | |
| 7777 } | |
| 7778 } | |
| 7779 | |
| 7780 PushOrMarkClosure::PushOrMarkClosure(CMSCollector* collector, | |
| 7781 MemRegion span, | |
| 7782 CMSBitMap* bitMap, CMSMarkStack* markStack, | |
| 7783 HeapWord* finger, MarkFromRootsClosure* parent) : | |
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7784 CMSOopClosure(collector->ref_processor()), |
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7785 _collector(collector), |
| 0 | 7786 _span(span), |
| 7787 _bitMap(bitMap), | |
| 7788 _markStack(markStack), | |
| 7789 _finger(finger), | |
| 935 | 7790 _parent(parent) |
| 0 | 7791 { } |
| 7792 | |
| 7793 Par_PushOrMarkClosure::Par_PushOrMarkClosure(CMSCollector* collector, | |
| 7794 MemRegion span, | |
| 7795 CMSBitMap* bit_map, | |
| 7796 OopTaskQueue* work_queue, | |
| 7797 CMSMarkStack* overflow_stack, | |
| 7798 HeapWord* finger, | |
| 7799 HeapWord** global_finger_addr, | |
| 7800 Par_MarkFromRootsClosure* parent) : | |
|
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7801 CMSOopClosure(collector->ref_processor()), |
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7802 _collector(collector), |
| 0 | 7803 _whole_span(collector->_span), |
| 7804 _span(span), | |
| 7805 _bit_map(bit_map), | |
| 7806 _work_queue(work_queue), | |
| 7807 _overflow_stack(overflow_stack), | |
| 7808 _finger(finger), | |
| 7809 _global_finger_addr(global_finger_addr), | |
| 935 | 7810 _parent(parent) |
| 0 | 7811 { } |
| 7812 | |
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7813 // Assumes thread-safe access by callers, who are |
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7814 // responsible for mutual exclusion. |
| 0 | 7815 void CMSCollector::lower_restart_addr(HeapWord* low) { |
| 7816 assert(_span.contains(low), "Out of bounds addr"); | |
| 7817 if (_restart_addr == NULL) { | |
| 7818 _restart_addr = low; | |
| 7819 } else { | |
| 7820 _restart_addr = MIN2(_restart_addr, low); | |
| 7821 } | |
| 7822 } | |
| 7823 | |
| 7824 // Upon stack overflow, we discard (part of) the stack, | |
| 7825 // remembering the least address amongst those discarded | |
| 7826 // in CMSCollector's _restart_address. | |
| 7827 void PushOrMarkClosure::handle_stack_overflow(HeapWord* lost) { | |
| 7828 // Remember the least grey address discarded | |
| 7829 HeapWord* ra = (HeapWord*)_markStack->least_value(lost); | |
| 7830 _collector->lower_restart_addr(ra); | |
| 7831 _markStack->reset(); // discard stack contents | |
| 7832 _markStack->expand(); // expand the stack if possible | |
| 7833 } | |
| 7834 | |
| 7835 // Upon stack overflow, we discard (part of) the stack, | |
| 7836 // remembering the least address amongst those discarded | |
| 7837 // in CMSCollector's _restart_address. | |
| 7838 void Par_PushOrMarkClosure::handle_stack_overflow(HeapWord* lost) { | |
| 7839 // We need to do this under a mutex to prevent other | |
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7840 // workers from interfering with the work done below. |
| 0 | 7841 MutexLockerEx ml(_overflow_stack->par_lock(), |
| 7842 Mutex::_no_safepoint_check_flag); | |
| 7843 // Remember the least grey address discarded | |
| 7844 HeapWord* ra = (HeapWord*)_overflow_stack->least_value(lost); | |
| 7845 _collector->lower_restart_addr(ra); | |
| 7846 _overflow_stack->reset(); // discard stack contents | |
| 7847 _overflow_stack->expand(); // expand the stack if possible | |
| 7848 } | |
| 7849 | |
|
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7850 void CMKlassClosure::do_klass(Klass* k) { |
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7851 assert(_oop_closure != NULL, "Not initialized?"); |
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7852 k->oops_do(_oop_closure); |
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7853 } |
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7854 |
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7855 void PushOrMarkClosure::do_oop(oop obj) { |
| 0 | 7856 // Ignore mark word because we are running concurrent with mutators. |
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7857 assert(obj->is_oop_or_null(true), "expected an oop or NULL"); |
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7858 HeapWord* addr = (HeapWord*)obj; |
| 0 | 7859 if (_span.contains(addr) && !_bitMap->isMarked(addr)) { |
| 7860 // Oop lies in _span and isn't yet grey or black | |
| 7861 _bitMap->mark(addr); // now grey | |
| 7862 if (addr < _finger) { | |
| 7863 // the bit map iteration has already either passed, or | |
| 7864 // sampled, this bit in the bit map; we'll need to | |
| 7865 // use the marking stack to scan this oop's oops. | |
| 7866 bool simulate_overflow = false; | |
| 7867 NOT_PRODUCT( | |
| 7868 if (CMSMarkStackOverflowALot && | |
| 7869 _collector->simulate_overflow()) { | |
| 7870 // simulate a stack overflow | |
| 7871 simulate_overflow = true; | |
| 7872 } | |
| 7873 ) | |
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7874 if (simulate_overflow || !_markStack->push(obj)) { // stack overflow |
| 0 | 7875 if (PrintCMSStatistics != 0) { |
| 7876 gclog_or_tty->print_cr("CMS marking stack overflow (benign) at " | |
| 7877 SIZE_FORMAT, _markStack->capacity()); | |
| 7878 } | |
| 7879 assert(simulate_overflow || _markStack->isFull(), "Else push should have succeeded"); | |
| 7880 handle_stack_overflow(addr); | |
| 7881 } | |
| 7882 } | |
| 7883 // anything including and to the right of _finger | |
| 7884 // will be scanned as we iterate over the remainder of the | |
| 7885 // bit map | |
| 7886 do_yield_check(); | |
| 7887 } | |
| 7888 } | |
| 7889 | |
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7890 void PushOrMarkClosure::do_oop(oop* p) { PushOrMarkClosure::do_oop_work(p); } |
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7891 void PushOrMarkClosure::do_oop(narrowOop* p) { PushOrMarkClosure::do_oop_work(p); } |
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7892 |
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7893 void Par_PushOrMarkClosure::do_oop(oop obj) { |
| 0 | 7894 // Ignore mark word because we are running concurrent with mutators. |
|
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7895 assert(obj->is_oop_or_null(true), "expected an oop or NULL"); |
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7896 HeapWord* addr = (HeapWord*)obj; |
| 0 | 7897 if (_whole_span.contains(addr) && !_bit_map->isMarked(addr)) { |
| 7898 // Oop lies in _span and isn't yet grey or black | |
| 7899 // We read the global_finger (volatile read) strictly after marking oop | |
| 7900 bool res = _bit_map->par_mark(addr); // now grey | |
| 7901 volatile HeapWord** gfa = (volatile HeapWord**)_global_finger_addr; | |
| 7902 // Should we push this marked oop on our stack? | |
| 7903 // -- if someone else marked it, nothing to do | |
| 7904 // -- if target oop is above global finger nothing to do | |
| 7905 // -- if target oop is in chunk and above local finger | |
| 7906 // then nothing to do | |
| 7907 // -- else push on work queue | |
| 7908 if ( !res // someone else marked it, they will deal with it | |
| 7909 || (addr >= *gfa) // will be scanned in a later task | |
| 7910 || (_span.contains(addr) && addr >= _finger)) { // later in this chunk | |
| 7911 return; | |
| 7912 } | |
| 7913 // the bit map iteration has already either passed, or | |
| 7914 // sampled, this bit in the bit map; we'll need to | |
| 7915 // use the marking stack to scan this oop's oops. | |
| 7916 bool simulate_overflow = false; | |
| 7917 NOT_PRODUCT( | |
| 7918 if (CMSMarkStackOverflowALot && | |
| 7919 _collector->simulate_overflow()) { | |
| 7920 // simulate a stack overflow | |
| 7921 simulate_overflow = true; | |
| 7922 } | |
| 7923 ) | |
| 7924 if (simulate_overflow || | |
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7925 !(_work_queue->push(obj) || _overflow_stack->par_push(obj))) { |
| 0 | 7926 // stack overflow |
| 7927 if (PrintCMSStatistics != 0) { | |
| 7928 gclog_or_tty->print_cr("CMS marking stack overflow (benign) at " | |
| 7929 SIZE_FORMAT, _overflow_stack->capacity()); | |
| 7930 } | |
| 7931 // We cannot assert that the overflow stack is full because | |
| 7932 // it may have been emptied since. | |
| 7933 assert(simulate_overflow || | |
| 7934 _work_queue->size() == _work_queue->max_elems(), | |
| 7935 "Else push should have succeeded"); | |
| 7936 handle_stack_overflow(addr); | |
| 7937 } | |
| 7938 do_yield_check(); | |
| 7939 } | |
| 7940 } | |
| 7941 | |
|
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7942 void Par_PushOrMarkClosure::do_oop(oop* p) { Par_PushOrMarkClosure::do_oop_work(p); } |
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7943 void Par_PushOrMarkClosure::do_oop(narrowOop* p) { Par_PushOrMarkClosure::do_oop_work(p); } |
| 0 | 7944 |
| 7945 PushAndMarkClosure::PushAndMarkClosure(CMSCollector* collector, | |
| 7946 MemRegion span, | |
| 7947 ReferenceProcessor* rp, | |
| 7948 CMSBitMap* bit_map, | |
| 7949 CMSBitMap* mod_union_table, | |
| 7950 CMSMarkStack* mark_stack, | |
| 7951 bool concurrent_precleaning): | |
|
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7952 CMSOopClosure(rp), |
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7953 _collector(collector), |
| 0 | 7954 _span(span), |
| 7955 _bit_map(bit_map), | |
| 7956 _mod_union_table(mod_union_table), | |
| 7957 _mark_stack(mark_stack), | |
| 935 | 7958 _concurrent_precleaning(concurrent_precleaning) |
| 0 | 7959 { |
| 7960 assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL"); | |
| 7961 } | |
| 7962 | |
| 7963 // Grey object rescan during pre-cleaning and second checkpoint phases -- | |
| 7964 // the non-parallel version (the parallel version appears further below.) | |
|
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7965 void PushAndMarkClosure::do_oop(oop obj) { |
|
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7966 // Ignore mark word verification. If during concurrent precleaning, |
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7967 // the object monitor may be locked. If during the checkpoint |
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7968 // phases, the object may already have been reached by a different |
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7969 // path and may be at the end of the global overflow list (so |
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7970 // the mark word may be NULL). |
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7971 assert(obj->is_oop_or_null(true /* ignore mark word */), |
| 0 | 7972 "expected an oop or NULL"); |
|
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7973 HeapWord* addr = (HeapWord*)obj; |
| 0 | 7974 // Check if oop points into the CMS generation |
| 7975 // and is not marked | |
| 7976 if (_span.contains(addr) && !_bit_map->isMarked(addr)) { | |
| 7977 // a white object ... | |
| 7978 _bit_map->mark(addr); // ... now grey | |
| 7979 // push on the marking stack (grey set) | |
| 7980 bool simulate_overflow = false; | |
| 7981 NOT_PRODUCT( | |
| 7982 if (CMSMarkStackOverflowALot && | |
| 7983 _collector->simulate_overflow()) { | |
| 7984 // simulate a stack overflow | |
| 7985 simulate_overflow = true; | |
| 7986 } | |
| 7987 ) | |
|
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7988 if (simulate_overflow || !_mark_stack->push(obj)) { |
| 0 | 7989 if (_concurrent_precleaning) { |
|
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7990 // During precleaning we can just dirty the appropriate card(s) |
| 0 | 7991 // in the mod union table, thus ensuring that the object remains |
|
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7992 // in the grey set and continue. In the case of object arrays |
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7993 // we need to dirty all of the cards that the object spans, |
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7994 // since the rescan of object arrays will be limited to the |
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7995 // dirty cards. |
| 14309 | 7996 // Note that no one can be interfering with us in this action |
|
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7997 // of dirtying the mod union table, so no locking or atomics |
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7998 // are required. |
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7999 if (obj->is_objArray()) { |
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8000 size_t sz = obj->size(); |
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8001 HeapWord* end_card_addr = (HeapWord*)round_to( |
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8002 (intptr_t)(addr+sz), CardTableModRefBS::card_size); |
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8003 MemRegion redirty_range = MemRegion(addr, end_card_addr); |
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8004 assert(!redirty_range.is_empty(), "Arithmetical tautology"); |
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8005 _mod_union_table->mark_range(redirty_range); |
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8006 } else { |
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8007 _mod_union_table->mark(addr); |
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|
8008 } |
| 0 | 8009 _collector->_ser_pmc_preclean_ovflw++; |
| 8010 } else { | |
| 8011 // During the remark phase, we need to remember this oop | |
| 8012 // in the overflow list. | |
|
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8013 _collector->push_on_overflow_list(obj); |
| 0 | 8014 _collector->_ser_pmc_remark_ovflw++; |
| 8015 } | |
| 8016 } | |
| 8017 } | |
| 8018 } | |
| 8019 | |
| 8020 Par_PushAndMarkClosure::Par_PushAndMarkClosure(CMSCollector* collector, | |
| 8021 MemRegion span, | |
| 8022 ReferenceProcessor* rp, | |
| 8023 CMSBitMap* bit_map, | |
|
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8024 OopTaskQueue* work_queue): |
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8025 CMSOopClosure(rp), |
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8026 _collector(collector), |
| 0 | 8027 _span(span), |
| 8028 _bit_map(bit_map), | |
| 935 | 8029 _work_queue(work_queue) |
| 0 | 8030 { |
| 8031 assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL"); | |
| 8032 } | |
| 8033 | |
|
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8034 void PushAndMarkClosure::do_oop(oop* p) { PushAndMarkClosure::do_oop_work(p); } |
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8035 void PushAndMarkClosure::do_oop(narrowOop* p) { PushAndMarkClosure::do_oop_work(p); } |
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8036 |
| 0 | 8037 // Grey object rescan during second checkpoint phase -- |
| 8038 // the parallel version. | |
|
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8039 void Par_PushAndMarkClosure::do_oop(oop obj) { |
| 0 | 8040 // In the assert below, we ignore the mark word because |
| 8041 // this oop may point to an already visited object that is | |
| 8042 // on the overflow stack (in which case the mark word has | |
| 8043 // been hijacked for chaining into the overflow stack -- | |
| 8044 // if this is the last object in the overflow stack then | |
| 8045 // its mark word will be NULL). Because this object may | |
| 8046 // have been subsequently popped off the global overflow | |
| 8047 // stack, and the mark word possibly restored to the prototypical | |
| 8048 // value, by the time we get to examined this failing assert in | |
| 8049 // the debugger, is_oop_or_null(false) may subsequently start | |
| 8050 // to hold. | |
|
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8051 assert(obj->is_oop_or_null(true), |
| 0 | 8052 "expected an oop or NULL"); |
|
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8053 HeapWord* addr = (HeapWord*)obj; |
| 0 | 8054 // Check if oop points into the CMS generation |
| 8055 // and is not marked | |
| 8056 if (_span.contains(addr) && !_bit_map->isMarked(addr)) { | |
| 8057 // a white object ... | |
| 8058 // If we manage to "claim" the object, by being the | |
| 8059 // first thread to mark it, then we push it on our | |
| 8060 // marking stack | |
| 8061 if (_bit_map->par_mark(addr)) { // ... now grey | |
| 8062 // push on work queue (grey set) | |
| 8063 bool simulate_overflow = false; | |
| 8064 NOT_PRODUCT( | |
| 8065 if (CMSMarkStackOverflowALot && | |
| 8066 _collector->par_simulate_overflow()) { | |
| 8067 // simulate a stack overflow | |
| 8068 simulate_overflow = true; | |
| 8069 } | |
| 8070 ) | |
|
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8071 if (simulate_overflow || !_work_queue->push(obj)) { |
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8072 _collector->par_push_on_overflow_list(obj); |
| 0 | 8073 _collector->_par_pmc_remark_ovflw++; // imprecise OK: no need to CAS |
| 8074 } | |
| 8075 } // Else, some other thread got there first | |
| 8076 } | |
| 8077 } | |
| 8078 | |
|
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8079 void Par_PushAndMarkClosure::do_oop(oop* p) { Par_PushAndMarkClosure::do_oop_work(p); } |
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8080 void Par_PushAndMarkClosure::do_oop(narrowOop* p) { Par_PushAndMarkClosure::do_oop_work(p); } |
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8081 |
| 0 | 8082 void CMSPrecleanRefsYieldClosure::do_yield_work() { |
| 8083 Mutex* bml = _collector->bitMapLock(); | |
| 8084 assert_lock_strong(bml); | |
| 8085 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 8086 "CMS thread should hold CMS token"); | |
| 8087 | |
| 8088 bml->unlock(); | |
| 8089 ConcurrentMarkSweepThread::desynchronize(true); | |
| 8090 | |
| 8091 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 8092 | |
| 8093 _collector->stopTimer(); | |
| 8094 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 8095 if (PrintCMSStatistics != 0) { | |
| 8096 _collector->incrementYields(); | |
| 8097 } | |
| 8098 _collector->icms_wait(); | |
| 8099 | |
| 8100 // See the comment in coordinator_yield() | |
| 8101 for (unsigned i = 0; i < CMSYieldSleepCount && | |
| 8102 ConcurrentMarkSweepThread::should_yield() && | |
| 8103 !CMSCollector::foregroundGCIsActive(); ++i) { | |
| 8104 os::sleep(Thread::current(), 1, false); | |
| 8105 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 8106 } | |
| 8107 | |
| 8108 ConcurrentMarkSweepThread::synchronize(true); | |
| 8109 bml->lock(); | |
| 8110 | |
| 8111 _collector->startTimer(); | |
| 8112 } | |
| 8113 | |
| 8114 bool CMSPrecleanRefsYieldClosure::should_return() { | |
| 8115 if (ConcurrentMarkSweepThread::should_yield()) { | |
| 8116 do_yield_work(); | |
| 8117 } | |
| 8118 return _collector->foregroundGCIsActive(); | |
| 8119 } | |
| 8120 | |
| 8121 void MarkFromDirtyCardsClosure::do_MemRegion(MemRegion mr) { | |
| 8122 assert(((size_t)mr.start())%CardTableModRefBS::card_size_in_words == 0, | |
| 8123 "mr should be aligned to start at a card boundary"); | |
| 8124 // We'd like to assert: | |
| 8125 // assert(mr.word_size()%CardTableModRefBS::card_size_in_words == 0, | |
| 8126 // "mr should be a range of cards"); | |
| 8127 // However, that would be too strong in one case -- the last | |
| 8128 // partition ends at _unallocated_block which, in general, can be | |
| 8129 // an arbitrary boundary, not necessarily card aligned. | |
| 8130 if (PrintCMSStatistics != 0) { | |
| 8131 _num_dirty_cards += | |
| 8132 mr.word_size()/CardTableModRefBS::card_size_in_words; | |
| 8133 } | |
| 8134 _space->object_iterate_mem(mr, &_scan_cl); | |
| 8135 } | |
| 8136 | |
| 8137 SweepClosure::SweepClosure(CMSCollector* collector, | |
| 8138 ConcurrentMarkSweepGeneration* g, | |
| 8139 CMSBitMap* bitMap, bool should_yield) : | |
| 8140 _collector(collector), | |
| 8141 _g(g), | |
| 8142 _sp(g->cmsSpace()), | |
| 8143 _limit(_sp->sweep_limit()), | |
| 8144 _freelistLock(_sp->freelistLock()), | |
| 8145 _bitMap(bitMap), | |
| 8146 _yield(should_yield), | |
| 8147 _inFreeRange(false), // No free range at beginning of sweep | |
| 8148 _freeRangeInFreeLists(false), // No free range at beginning of sweep | |
| 8149 _lastFreeRangeCoalesced(false), | |
| 8150 _freeFinger(g->used_region().start()) | |
| 8151 { | |
| 8152 NOT_PRODUCT( | |
| 8153 _numObjectsFreed = 0; | |
| 8154 _numWordsFreed = 0; | |
| 8155 _numObjectsLive = 0; | |
| 8156 _numWordsLive = 0; | |
| 8157 _numObjectsAlreadyFree = 0; | |
| 8158 _numWordsAlreadyFree = 0; | |
| 8159 _last_fc = NULL; | |
| 8160 | |
| 8161 _sp->initializeIndexedFreeListArrayReturnedBytes(); | |
|
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8162 _sp->dictionary()->initialize_dict_returned_bytes(); |
| 0 | 8163 ) |
| 8164 assert(_limit >= _sp->bottom() && _limit <= _sp->end(), | |
| 8165 "sweep _limit out of bounds"); | |
| 8166 if (CMSTraceSweeper) { | |
|
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8167 gclog_or_tty->print_cr("\n====================\nStarting new sweep with limit " PTR_FORMAT, |
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8168 _limit); |
|
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|
8169 } |
|
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8170 } |
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8171 |
|
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|
8172 void SweepClosure::print_on(outputStream* st) const { |
|
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|
8173 tty->print_cr("_sp = [" PTR_FORMAT "," PTR_FORMAT ")", |
|
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8174 _sp->bottom(), _sp->end()); |
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|
8175 tty->print_cr("_limit = " PTR_FORMAT, _limit); |
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|
8176 tty->print_cr("_freeFinger = " PTR_FORMAT, _freeFinger); |
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|
8177 NOT_PRODUCT(tty->print_cr("_last_fc = " PTR_FORMAT, _last_fc);) |
|
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|
8178 tty->print_cr("_inFreeRange = %d, _freeRangeInFreeLists = %d, _lastFreeRangeCoalesced = %d", |
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|
8179 _inFreeRange, _freeRangeInFreeLists, _lastFreeRangeCoalesced); |
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8180 } |
|
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8181 |
|
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|
8182 #ifndef PRODUCT |
|
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8183 // Assertion checking only: no useful work in product mode -- |
|
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8184 // however, if any of the flags below become product flags, |
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8185 // you may need to review this code to see if it needs to be |
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changeset
|
8186 // enabled in product mode. |
| 0 | 8187 SweepClosure::~SweepClosure() { |
| 8188 assert_lock_strong(_freelistLock); | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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diff
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|
8189 assert(_limit >= _sp->bottom() && _limit <= _sp->end(), |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
changeset
|
8190 "sweep _limit out of bounds"); |
| 0 | 8191 if (inFreeRange()) { |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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parents:
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changeset
|
8192 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:
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changeset
|
8193 print(); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8194 ShouldNotReachHere(); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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parents:
3356
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changeset
|
8195 } |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8196 if (Verbose && PrintGC) { |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8197 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
|
8198 _numObjectsFreed, _numWordsFreed*sizeof(HeapWord)); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8199 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
|
8200 SIZE_FORMAT" bytes " |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8201 "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
|
8202 _numObjectsLive, _numWordsLive*sizeof(HeapWord), |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
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|
8203 _numObjectsAlreadyFree, _numWordsAlreadyFree*sizeof(HeapWord)); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8204 size_t totalBytes = (_numWordsFreed + _numWordsLive + _numWordsAlreadyFree) |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8205 * sizeof(HeapWord); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8206 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
|
8207 |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
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changeset
|
8208 if (PrintCMSStatistics && CMSVerifyReturnedBytes) { |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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parents:
3356
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changeset
|
8209 size_t indexListReturnedBytes = _sp->sumIndexedFreeListArrayReturnedBytes(); |
|
6028
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
parents:
6026
diff
changeset
|
8210 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
|
8211 size_t returned_bytes = indexListReturnedBytes + dict_returned_bytes; |
|
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
parents:
6026
diff
changeset
|
8212 gclog_or_tty->print("Returned "SIZE_FORMAT" bytes", returned_bytes); |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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parents:
3356
diff
changeset
|
8213 gclog_or_tty->print(" Indexed List Returned "SIZE_FORMAT" bytes", |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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parents:
3356
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changeset
|
8214 indexListReturnedBytes); |
|
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(" Dictionary Returned "SIZE_FORMAT" bytes", |
|
6028
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
parents:
6026
diff
changeset
|
8216 dict_returned_bytes); |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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parents:
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changeset
|
8217 } |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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parents:
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changeset
|
8218 } |
| 0 | 8219 if (CMSTraceSweeper) { |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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parents:
3356
diff
changeset
|
8220 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:
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changeset
|
8221 _limit); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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parents:
3356
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changeset
|
8222 } |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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parents:
3356
diff
changeset
|
8223 } |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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parents:
3356
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changeset
|
8224 #endif // PRODUCT |
| 0 | 8225 |
| 8226 void SweepClosure::initialize_free_range(HeapWord* freeFinger, | |
| 8227 bool freeRangeInFreeLists) { | |
| 8228 if (CMSTraceSweeper) { | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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parents:
1994
diff
changeset
|
8229 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
|
8230 freeFinger, freeRangeInFreeLists); |
| 0 | 8231 } |
| 8232 assert(!inFreeRange(), "Trampling existing free range"); | |
| 8233 set_inFreeRange(true); | |
| 8234 set_lastFreeRangeCoalesced(false); | |
| 8235 | |
| 8236 set_freeFinger(freeFinger); | |
| 8237 set_freeRangeInFreeLists(freeRangeInFreeLists); | |
| 8238 if (CMSTestInFreeList) { | |
| 8239 if (freeRangeInFreeLists) { | |
| 8240 FreeChunk* fc = (FreeChunk*) freeFinger; | |
|
6028
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
parents:
6026
diff
changeset
|
8241 assert(fc->is_free(), "A chunk on the free list should be free."); |
| 0 | 8242 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
|
8243 assert(_sp->verify_chunk_in_free_list(fc), "Chunk is not in free lists"); |
| 0 | 8244 } |
| 8245 } | |
| 8246 } | |
| 8247 | |
| 8248 // Note that the sweeper runs concurrently with mutators. Thus, | |
| 8249 // it is possible for direct allocation in this generation to happen | |
| 8250 // in the middle of the sweep. Note that the sweeper also coalesces | |
| 8251 // contiguous free blocks. Thus, unless the sweeper and the allocator | |
| 8252 // synchronize appropriately freshly allocated blocks may get swept up. | |
| 8253 // This is accomplished by the sweeper locking the free lists while | |
| 8254 // it is sweeping. Thus blocks that are determined to be free are | |
| 8255 // indeed free. There is however one additional complication: | |
| 8256 // blocks that have been allocated since the final checkpoint and | |
| 8257 // mark, will not have been marked and so would be treated as | |
| 8258 // unreachable and swept up. To prevent this, the allocator marks | |
| 8259 // the bit map when allocating during the sweep phase. This leads, | |
| 8260 // however, to a further complication -- objects may have been allocated | |
| 8261 // but not yet initialized -- in the sense that the header isn't yet | |
| 8262 // installed. The sweeper can not then determine the size of the block | |
| 8263 // in order to skip over it. To deal with this case, we use a technique | |
| 8264 // (due to Printezis) to encode such uninitialized block sizes in the | |
| 8265 // bit map. Since the bit map uses a bit per every HeapWord, but the | |
| 8266 // CMS generation has a minimum object size of 3 HeapWords, it follows | |
| 8267 // that "normal marks" won't be adjacent in the bit map (there will | |
| 8268 // always be at least two 0 bits between successive 1 bits). We make use | |
| 8269 // of these "unused" bits to represent uninitialized blocks -- the bit | |
| 8270 // corresponding to the start of the uninitialized object and the next | |
| 8271 // bit are both set. Finally, a 1 bit marks the end of the object that | |
| 8272 // started with the two consecutive 1 bits to indicate its potentially | |
| 8273 // uninitialized state. | |
| 8274 | |
| 8275 size_t SweepClosure::do_blk_careful(HeapWord* addr) { | |
| 8276 FreeChunk* fc = (FreeChunk*)addr; | |
| 8277 size_t res; | |
| 8278 | |
|
1720
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
parents:
1716
diff
changeset
|
8279 // 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
|
8280 // 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
|
8281 // 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
|
8282 // 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
|
8283 // 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
|
8284 // 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
|
8285 // 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
|
8286 if (addr >= _limit) { // we have swept up to or past the limit: finish up |
| 0 | 8287 assert(_limit >= _sp->bottom() && _limit <= _sp->end(), |
| 8288 "sweep _limit out of bounds"); | |
|
1720
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
parents:
1716
diff
changeset
|
8289 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
|
8290 // 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
|
8291 // coalesced chunk to the appropriate free list. |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8292 if (inFreeRange()) { |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8293 assert(freeFinger() >= _sp->bottom() && freeFinger() < _limit, |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8294 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
|
8295 flush_cur_free_chunk(freeFinger(), |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8296 pointer_delta(addr, freeFinger())); |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8297 if (CMSTraceSweeper) { |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8298 gclog_or_tty->print("Sweep: last chunk: "); |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8299 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
|
8300 "[coalesced:"SIZE_FORMAT"]\n", |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8301 freeFinger(), pointer_delta(addr, freeFinger()), |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8302 lastFreeRangeCoalesced()); |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8303 } |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8304 } |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8305 |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8306 // help the iterator loop finish |
|
1720
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
parents:
1716
diff
changeset
|
8307 return pointer_delta(_sp->end(), addr); |
|
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
parents:
1716
diff
changeset
|
8308 } |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8309 |
|
1720
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
parents:
1716
diff
changeset
|
8310 assert(addr < _limit, "sweep invariant"); |
| 0 | 8311 // check if we should yield |
| 8312 do_yield_check(addr); | |
|
6028
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
parents:
6026
diff
changeset
|
8313 if (fc->is_free()) { |
| 0 | 8314 // Chunk that is already free |
| 8315 res = fc->size(); | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8316 do_already_free_chunk(fc); |
| 0 | 8317 debug_only(_sp->verifyFreeLists()); |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8318 // 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
|
8319 // 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
|
8320 // 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
|
8321 // 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
|
8322 // (erstwhile) header of all the coalesced blocks but the |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8323 // first, so the first disjunct in the assert will not hold |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8324 // in that specific case (in which case the second disjunct |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8325 // will hold). |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8326 assert(res == fc->size() || ((HeapWord*)fc) + res >= _limit, |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8327 "Otherwise the size info doesn't change at this step"); |
| 0 | 8328 NOT_PRODUCT( |
| 8329 _numObjectsAlreadyFree++; | |
| 8330 _numWordsAlreadyFree += res; | |
| 8331 ) | |
| 8332 NOT_PRODUCT(_last_fc = fc;) | |
| 8333 } else if (!_bitMap->isMarked(addr)) { | |
| 8334 // Chunk is fresh garbage | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8335 res = do_garbage_chunk(fc); |
| 0 | 8336 debug_only(_sp->verifyFreeLists()); |
| 8337 NOT_PRODUCT( | |
| 8338 _numObjectsFreed++; | |
| 8339 _numWordsFreed += res; | |
| 8340 ) | |
| 8341 } else { | |
| 8342 // Chunk that is alive. | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8343 res = do_live_chunk(fc); |
| 0 | 8344 debug_only(_sp->verifyFreeLists()); |
| 8345 NOT_PRODUCT( | |
| 8346 _numObjectsLive++; | |
| 8347 _numWordsLive += res; | |
| 8348 ) | |
| 8349 } | |
| 8350 return res; | |
| 8351 } | |
| 8352 | |
| 8353 // For the smart allocation, record following | |
| 8354 // split deaths - a free chunk is removed from its free list because | |
| 8355 // it is being split into two or more chunks. | |
| 8356 // split birth - a free chunk is being added to its free list because | |
| 8357 // a larger free chunk has been split and resulted in this free chunk. | |
| 8358 // coal death - a free chunk is being removed from its free list because | |
| 8359 // it is being coalesced into a large free chunk. | |
| 8360 // coal birth - a free chunk is being added to its free list because | |
| 8361 // it was created when two or more free chunks where coalesced into | |
| 8362 // this free chunk. | |
| 8363 // | |
| 8364 // These statistics are used to determine the desired number of free | |
| 8365 // chunks of a given size. The desired number is chosen to be relative | |
| 8366 // to the end of a CMS sweep. The desired number at the end of a sweep | |
| 8367 // is the | |
| 8368 // count-at-end-of-previous-sweep (an amount that was enough) | |
| 8369 // - count-at-beginning-of-current-sweep (the excess) | |
| 8370 // + split-births (gains in this size during interval) | |
| 8371 // - split-deaths (demands on this size during interval) | |
| 8372 // where the interval is from the end of one sweep to the end of the | |
| 8373 // next. | |
| 8374 // | |
| 8375 // When sweeping the sweeper maintains an accumulated chunk which is | |
| 8376 // the chunk that is made up of chunks that have been coalesced. That | |
| 8377 // will be termed the left-hand chunk. A new chunk of garbage that | |
| 8378 // is being considered for coalescing will be referred to as the | |
| 8379 // right-hand chunk. | |
| 8380 // | |
| 8381 // When making a decision on whether to coalesce a right-hand chunk with | |
| 8382 // the current left-hand chunk, the current count vs. the desired count | |
| 8383 // of the left-hand chunk is considered. Also if the right-hand chunk | |
| 8384 // is near the large chunk at the end of the heap (see | |
| 8385 // ConcurrentMarkSweepGeneration::isNearLargestChunk()), then the | |
| 8386 // left-hand chunk is coalesced. | |
| 8387 // | |
| 8388 // When making a decision about whether to split a chunk, the desired count | |
| 8389 // vs. the current count of the candidate to be split is also considered. | |
| 8390 // If the candidate is underpopulated (currently fewer chunks than desired) | |
| 8391 // a chunk of an overpopulated (currently more chunks than desired) size may | |
| 8392 // be chosen. The "hint" associated with a free list, if non-null, points | |
| 8393 // to a free list which may be overpopulated. | |
| 8394 // | |
| 8395 | |
|
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|
8396 void SweepClosure::do_already_free_chunk(FreeChunk* fc) { |
|
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|
8397 const size_t size = fc->size(); |
| 0 | 8398 // Chunks that cannot be coalesced are not in the |
| 8399 // free lists. | |
| 8400 if (CMSTestInFreeList && !fc->cantCoalesce()) { | |
|
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|
8401 assert(_sp->verify_chunk_in_free_list(fc), |
| 0 | 8402 "free chunk should be in free lists"); |
| 8403 } | |
| 8404 // a chunk that is already free, should not have been | |
| 8405 // marked in the bit map | |
|
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|
8406 HeapWord* const addr = (HeapWord*) fc; |
| 0 | 8407 assert(!_bitMap->isMarked(addr), "free chunk should be unmarked"); |
| 8408 // Verify that the bit map has no bits marked between | |
| 8409 // addr and purported end of this block. | |
| 8410 _bitMap->verifyNoOneBitsInRange(addr + 1, addr + size); | |
| 8411 | |
|
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|
8412 // Some chunks cannot be coalesced under any circumstances. |
| 0 | 8413 // See the definition of cantCoalesce(). |
| 8414 if (!fc->cantCoalesce()) { | |
| 8415 // This chunk can potentially be coalesced. | |
| 8416 if (_sp->adaptive_freelists()) { | |
| 8417 // All the work is done in | |
|
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|
8418 do_post_free_or_garbage_chunk(fc, size); |
| 0 | 8419 } else { // Not adaptive free lists |
| 8420 // this is a free chunk that can potentially be coalesced by the sweeper; | |
| 8421 if (!inFreeRange()) { | |
| 8422 // if the next chunk is a free block that can't be coalesced | |
| 8423 // it doesn't make sense to remove this chunk from the free lists | |
| 8424 FreeChunk* nextChunk = (FreeChunk*)(addr + size); | |
|
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|
8425 assert((HeapWord*)nextChunk <= _sp->end(), "Chunk size out of bounds?"); |
|
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|
8426 if ((HeapWord*)nextChunk < _sp->end() && // There is another free chunk to the right ... |
|
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|
8427 nextChunk->is_free() && // ... which is free... |
|
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|
8428 nextChunk->cantCoalesce()) { // ... but can't be coalesced |
| 0 | 8429 // nothing to do |
| 8430 } else { | |
| 8431 // Potentially the start of a new free range: | |
| 8432 // Don't eagerly remove it from the free lists. | |
| 8433 // No need to remove it if it will just be put | |
| 8434 // back again. (Also from a pragmatic point of view | |
| 8435 // if it is a free block in a region that is beyond | |
| 8436 // any allocated blocks, an assertion will fail) | |
| 8437 // Remember the start of a free run. | |
| 8438 initialize_free_range(addr, true); | |
| 8439 // end - can coalesce with next chunk | |
| 8440 } | |
| 8441 } else { | |
| 8442 // the midst of a free range, we are coalescing | |
|
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|
8443 print_free_block_coalesced(fc); |
| 0 | 8444 if (CMSTraceSweeper) { |
| 8445 gclog_or_tty->print(" -- pick up free block 0x%x (%d)\n", fc, size); | |
| 8446 } | |
| 8447 // remove it from the free lists | |
| 8448 _sp->removeFreeChunkFromFreeLists(fc); | |
| 8449 set_lastFreeRangeCoalesced(true); | |
| 8450 // If the chunk is being coalesced and the current free range is | |
| 8451 // in the free lists, remove the current free range so that it | |
| 8452 // will be returned to the free lists in its entirety - all | |
| 8453 // the coalesced pieces included. | |
| 8454 if (freeRangeInFreeLists()) { | |
| 8455 FreeChunk* ffc = (FreeChunk*) freeFinger(); | |
| 8456 assert(ffc->size() == pointer_delta(addr, freeFinger()), | |
| 8457 "Size of free range is inconsistent with chunk size."); | |
| 8458 if (CMSTestInFreeList) { | |
|
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|
8459 assert(_sp->verify_chunk_in_free_list(ffc), |
| 0 | 8460 "free range is not in free lists"); |
| 8461 } | |
| 8462 _sp->removeFreeChunkFromFreeLists(ffc); | |
| 8463 set_freeRangeInFreeLists(false); | |
| 8464 } | |
| 8465 } | |
| 8466 } | |
|
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|
8467 // Note that if the chunk is not coalescable (the else arm |
|
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|
8468 // below), we unconditionally flush, without needing to do |
|
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|
8469 // a "lookahead," as we do below. |
|
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changeset
|
8470 if (inFreeRange()) lookahead_and_flush(fc, size); |
| 0 | 8471 } else { |
| 8472 // Code path common to both original and adaptive free lists. | |
| 8473 | |
| 8474 // cant coalesce with previous block; this should be treated | |
| 8475 // as the end of a free run if any | |
| 8476 if (inFreeRange()) { | |
| 8477 // we kicked some butt; time to pick up the garbage | |
|
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|
8478 assert(freeFinger() < addr, "freeFinger points too high"); |
|
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|
8479 flush_cur_free_chunk(freeFinger(), pointer_delta(addr, freeFinger())); |
| 0 | 8480 } |
| 8481 // else, nothing to do, just continue | |
| 8482 } | |
| 8483 } | |
| 8484 | |
|
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|
8485 size_t SweepClosure::do_garbage_chunk(FreeChunk* fc) { |
| 0 | 8486 // This is a chunk of garbage. It is not in any free list. |
| 8487 // Add it to a free list or let it possibly be coalesced into | |
| 8488 // a larger chunk. | |
|
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|
8489 HeapWord* const addr = (HeapWord*) fc; |
|
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|
8490 const size_t size = CompactibleFreeListSpace::adjustObjectSize(oop(addr)->size()); |
| 0 | 8491 |
| 8492 if (_sp->adaptive_freelists()) { | |
| 8493 // Verify that the bit map has no bits marked between | |
| 8494 // addr and purported end of just dead object. | |
| 8495 _bitMap->verifyNoOneBitsInRange(addr + 1, addr + size); | |
| 8496 | |
|
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|
8497 do_post_free_or_garbage_chunk(fc, size); |
| 0 | 8498 } else { |
| 8499 if (!inFreeRange()) { | |
| 8500 // start of a new free range | |
| 8501 assert(size > 0, "A free range should have a size"); | |
| 8502 initialize_free_range(addr, false); | |
| 8503 } else { | |
| 8504 // this will be swept up when we hit the end of the | |
| 8505 // free range | |
| 8506 if (CMSTraceSweeper) { | |
| 8507 gclog_or_tty->print(" -- pick up garbage 0x%x (%d) \n", fc, size); | |
| 8508 } | |
| 8509 // If the chunk is being coalesced and the current free range is | |
| 8510 // in the free lists, remove the current free range so that it | |
| 8511 // will be returned to the free lists in its entirety - all | |
| 8512 // the coalesced pieces included. | |
| 8513 if (freeRangeInFreeLists()) { | |
| 8514 FreeChunk* ffc = (FreeChunk*)freeFinger(); | |
| 8515 assert(ffc->size() == pointer_delta(addr, freeFinger()), | |
| 8516 "Size of free range is inconsistent with chunk size."); | |
| 8517 if (CMSTestInFreeList) { | |
|
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|
8518 assert(_sp->verify_chunk_in_free_list(ffc), |
| 0 | 8519 "free range is not in free lists"); |
| 8520 } | |
| 8521 _sp->removeFreeChunkFromFreeLists(ffc); | |
| 8522 set_freeRangeInFreeLists(false); | |
| 8523 } | |
| 8524 set_lastFreeRangeCoalesced(true); | |
| 8525 } | |
| 8526 // this will be swept up when we hit the end of the free range | |
| 8527 | |
| 8528 // Verify that the bit map has no bits marked between | |
| 8529 // addr and purported end of just dead object. | |
| 8530 _bitMap->verifyNoOneBitsInRange(addr + 1, addr + size); | |
| 8531 } | |
|
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|
8532 assert(_limit >= addr + size, |
|
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|
8533 "A freshly garbage chunk can't possibly straddle over _limit"); |
|
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|
8534 if (inFreeRange()) lookahead_and_flush(fc, size); |
| 0 | 8535 return size; |
| 8536 } | |
| 8537 | |
|
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|
8538 size_t SweepClosure::do_live_chunk(FreeChunk* fc) { |
| 0 | 8539 HeapWord* addr = (HeapWord*) fc; |
| 8540 // The sweeper has just found a live object. Return any accumulated | |
| 8541 // left hand chunk to the free lists. | |
| 8542 if (inFreeRange()) { | |
|
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|
8543 assert(freeFinger() < addr, "freeFinger points too high"); |
|
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|
8544 flush_cur_free_chunk(freeFinger(), pointer_delta(addr, freeFinger())); |
|
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|
8545 } |
|
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|
8546 |
|
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|
8547 // This object is live: we'd normally expect this to be |
| 0 | 8548 // an oop, and like to assert the following: |
| 8549 // assert(oop(addr)->is_oop(), "live block should be an oop"); | |
| 8550 // However, as we commented above, this may be an object whose | |
| 8551 // header hasn't yet been initialized. | |
| 8552 size_t size; | |
| 8553 assert(_bitMap->isMarked(addr), "Tautology for this control point"); | |
| 8554 if (_bitMap->isMarked(addr + 1)) { | |
| 8555 // Determine the size from the bit map, rather than trying to | |
| 8556 // compute it from the object header. | |
| 8557 HeapWord* nextOneAddr = _bitMap->getNextMarkedWordAddress(addr + 2); | |
| 8558 size = pointer_delta(nextOneAddr + 1, addr); | |
| 8559 assert(size == CompactibleFreeListSpace::adjustObjectSize(size), | |
| 8560 "alignment problem"); | |
| 8561 | |
| 9152 | 8562 #ifdef ASSERT |
|
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|
8563 if (oop(addr)->klass_or_null() != NULL) { |
| 0 | 8564 // Ignore mark word because we are running concurrent with mutators |
| 8565 assert(oop(addr)->is_oop(true), "live block should be an oop"); | |
| 8566 assert(size == | |
| 8567 CompactibleFreeListSpace::adjustObjectSize(oop(addr)->size()), | |
| 8568 "P-mark and computed size do not agree"); | |
| 8569 } | |
|
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|
8570 #endif |
| 0 | 8571 |
| 8572 } else { | |
| 8573 // This should be an initialized object that's alive. | |
|
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|
8574 assert(oop(addr)->klass_or_null() != NULL, |
| 0 | 8575 "Should be an initialized object"); |
| 8576 // Ignore mark word because we are running concurrent with mutators | |
| 8577 assert(oop(addr)->is_oop(true), "live block should be an oop"); | |
| 8578 // Verify that the bit map has no bits marked between | |
| 8579 // addr and purported end of this block. | |
| 8580 size = CompactibleFreeListSpace::adjustObjectSize(oop(addr)->size()); | |
| 8581 assert(size >= 3, "Necessary for Printezis marks to work"); | |
| 8582 assert(!_bitMap->isMarked(addr+1), "Tautology for this control point"); | |
| 8583 DEBUG_ONLY(_bitMap->verifyNoOneBitsInRange(addr+2, addr+size);) | |
| 8584 } | |
| 8585 return size; | |
| 8586 } | |
| 8587 | |
|
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|
8588 void SweepClosure::do_post_free_or_garbage_chunk(FreeChunk* fc, |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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|
8589 size_t chunkSize) { |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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|
8590 // do_post_free_or_garbage_chunk() should only be called in the case |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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diff
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|
8591 // of the adaptive free list allocator. |
|
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|
8592 const bool fcInFreeLists = fc->is_free(); |
| 0 | 8593 assert(_sp->adaptive_freelists(), "Should only be used in this case."); |
| 8594 assert((HeapWord*)fc <= _limit, "sweep invariant"); | |
| 8595 if (CMSTestInFreeList && fcInFreeLists) { | |
|
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|
8596 assert(_sp->verify_chunk_in_free_list(fc), "free chunk is not in free lists"); |
|
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|
8597 } |
| 0 | 8598 |
| 8599 if (CMSTraceSweeper) { | |
| 8600 gclog_or_tty->print_cr(" -- pick up another chunk at 0x%x (%d)", fc, chunkSize); | |
| 8601 } | |
| 8602 | |
|
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|
8603 HeapWord* const fc_addr = (HeapWord*) fc; |
| 0 | 8604 |
| 8605 bool coalesce; | |
|
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|
8606 const size_t left = pointer_delta(fc_addr, freeFinger()); |
|
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|
8607 const size_t right = chunkSize; |
| 0 | 8608 switch (FLSCoalescePolicy) { |
| 8609 // numeric value forms a coalition aggressiveness metric | |
| 8610 case 0: { // never coalesce | |
| 8611 coalesce = false; | |
| 8612 break; | |
| 8613 } | |
| 8614 case 1: { // coalesce if left & right chunks on overpopulated lists | |
| 8615 coalesce = _sp->coalOverPopulated(left) && | |
| 8616 _sp->coalOverPopulated(right); | |
| 8617 break; | |
| 8618 } | |
| 8619 case 2: { // coalesce if left chunk on overpopulated list (default) | |
| 8620 coalesce = _sp->coalOverPopulated(left); | |
| 8621 break; | |
| 8622 } | |
| 8623 case 3: { // coalesce if left OR right chunk on overpopulated list | |
| 8624 coalesce = _sp->coalOverPopulated(left) || | |
| 8625 _sp->coalOverPopulated(right); | |
| 8626 break; | |
| 8627 } | |
| 8628 case 4: { // always coalesce | |
| 8629 coalesce = true; | |
| 8630 break; | |
| 8631 } | |
| 8632 default: | |
| 8633 ShouldNotReachHere(); | |
| 8634 } | |
| 8635 | |
| 8636 // Should the current free range be coalesced? | |
| 8637 // If the chunk is in a free range and either we decided to coalesce above | |
| 8638 // or the chunk is near the large block at the end of the heap | |
| 8639 // (isNearLargestChunk() returns true), then coalesce this chunk. | |
|
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|
8640 const bool doCoalesce = inFreeRange() |
|
537a4053b0f9
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|
8641 && (coalesce || _g->isNearLargestChunk(fc_addr)); |
| 0 | 8642 if (doCoalesce) { |
| 8643 // Coalesce the current free range on the left with the new | |
| 8644 // chunk on the right. If either is on a free list, | |
| 8645 // it must be removed from the list and stashed in the closure. | |
| 8646 if (freeRangeInFreeLists()) { | |
|
3746
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3356
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|
8647 FreeChunk* const ffc = (FreeChunk*)freeFinger(); |
|
537a4053b0f9
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|
8648 assert(ffc->size() == pointer_delta(fc_addr, freeFinger()), |
| 0 | 8649 "Size of free range is inconsistent with chunk size."); |
| 8650 if (CMSTestInFreeList) { | |
|
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|
8651 assert(_sp->verify_chunk_in_free_list(ffc), |
| 0 | 8652 "Chunk is not in free lists"); |
| 8653 } | |
| 8654 _sp->coalDeath(ffc->size()); | |
| 8655 _sp->removeFreeChunkFromFreeLists(ffc); | |
| 8656 set_freeRangeInFreeLists(false); | |
| 8657 } | |
| 8658 if (fcInFreeLists) { | |
| 8659 _sp->coalDeath(chunkSize); | |
| 8660 assert(fc->size() == chunkSize, | |
| 8661 "The chunk has the wrong size or is not in the free lists"); | |
| 8662 _sp->removeFreeChunkFromFreeLists(fc); | |
| 8663 } | |
| 8664 set_lastFreeRangeCoalesced(true); | |
|
3746
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changeset
|
8665 print_free_block_coalesced(fc); |
| 0 | 8666 } else { // not in a free range and/or should not coalesce |
| 8667 // Return the current free range and start a new one. | |
| 8668 if (inFreeRange()) { | |
| 8669 // In a free range but cannot coalesce with the right hand chunk. | |
| 8670 // Put the current free range into the free lists. | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
changeset
|
8671 flush_cur_free_chunk(freeFinger(), |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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parents:
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diff
changeset
|
8672 pointer_delta(fc_addr, freeFinger())); |
| 0 | 8673 } |
| 8674 // Set up for new free range. Pass along whether the right hand | |
| 8675 // chunk is in the free lists. | |
| 8676 initialize_free_range((HeapWord*)fc, fcInFreeLists); | |
| 8677 } | |
| 8678 } | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
changeset
|
8679 |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8680 // Lookahead flush: |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8681 // If we are tracking a free range, and this is the last chunk that |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8682 // we'll look at because its end crosses past _limit, we'll preemptively |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8683 // flush it along with any free range we may be holding on to. Note that |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8684 // this can be the case only for an already free or freshly garbage |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8685 // chunk. If this block is an object, it can never straddle |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8686 // over _limit. The "straddling" occurs when _limit is set at |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8687 // the previous end of the space when this cycle started, and |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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|
8688 // a subsequent heap expansion caused the previously co-terminal |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8689 // free block to be coalesced with the newly expanded portion, |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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parents:
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changeset
|
8690 // thus rendering _limit a non-block-boundary making it dangerous |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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parents:
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|
8691 // for the sweeper to step over and examine. |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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|
8692 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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|
8693 assert(inFreeRange(), "Should only be called if currently in a free range."); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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parents:
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|
8694 HeapWord* const eob = ((HeapWord*)fc) + chunk_size; |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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parents:
3356
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|
8695 assert(_sp->used_region().contains(eob - 1), |
|
12112
1bb10d3170fa
8022817: CMS should not shrink if compaction was not done
jmasa
parents:
12088
diff
changeset
|
8696 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
|
8697 " out of bounds wrt _sp = [" PTR_FORMAT "," PTR_FORMAT ")" |
|
3746
537a4053b0f9
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parents:
3356
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|
8698 " when examining fc = " PTR_FORMAT "(" SIZE_FORMAT ")", |
|
12112
1bb10d3170fa
8022817: CMS should not shrink if compaction was not done
jmasa
parents:
12088
diff
changeset
|
8699 eob, eob-1, _limit, _sp->bottom(), _sp->end(), fc, chunk_size)); |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8700 if (eob >= _limit) { |
|
6028
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
parents:
6026
diff
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|
8701 assert(eob == _limit || fc->is_free(), "Only a free chunk should allow us to cross over the limit"); |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8702 if (CMSTraceSweeper) { |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8703 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
|
8704 "[" PTR_FORMAT "," PTR_FORMAT ") in space " |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8705 "[" PTR_FORMAT "," PTR_FORMAT ")", |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8706 _limit, fc, eob, _sp->bottom(), _sp->end()); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8707 } |
|
537a4053b0f9
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3356
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changeset
|
8708 // Return the storage we are tracking back into the free lists. |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8709 if (CMSTraceSweeper) { |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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|
8710 gclog_or_tty->print_cr("Flushing ... "); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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parents:
3356
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|
8711 } |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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parents:
3356
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changeset
|
8712 assert(freeFinger() < eob, "Error"); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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parents:
3356
diff
changeset
|
8713 flush_cur_free_chunk( freeFinger(), pointer_delta(eob, freeFinger())); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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parents:
3356
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|
8714 } |
|
537a4053b0f9
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ysr
parents:
3356
diff
changeset
|
8715 } |
|
537a4053b0f9
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ysr
parents:
3356
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|
8716 |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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parents:
1994
diff
changeset
|
8717 void SweepClosure::flush_cur_free_chunk(HeapWord* chunk, size_t size) { |
| 0 | 8718 assert(inFreeRange(), "Should only be called if currently in a free range."); |
| 8719 assert(size > 0, | |
| 8720 "A zero sized chunk cannot be added to the free lists."); | |
| 8721 if (!freeRangeInFreeLists()) { | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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parents:
1994
diff
changeset
|
8722 if (CMSTestInFreeList) { |
| 0 | 8723 FreeChunk* fc = (FreeChunk*) chunk; |
|
6028
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
parents:
6026
diff
changeset
|
8724 fc->set_size(size); |
|
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
parents:
6026
diff
changeset
|
8725 assert(!_sp->verify_chunk_in_free_list(fc), |
| 0 | 8726 "chunk should not be in free lists yet"); |
| 8727 } | |
| 8728 if (CMSTraceSweeper) { | |
| 8729 gclog_or_tty->print_cr(" -- add free block 0x%x (%d) to free lists", | |
| 8730 chunk, size); | |
| 8731 } | |
| 8732 // A new free range is going to be starting. The current | |
| 8733 // free range has not been added to the free lists yet or | |
| 8734 // was removed so add it back. | |
| 8735 // If the current free range was coalesced, then the death | |
| 8736 // of the free range was recorded. Record a birth now. | |
| 8737 if (lastFreeRangeCoalesced()) { | |
| 8738 _sp->coalBirth(size); | |
| 8739 } | |
| 8740 _sp->addChunkAndRepairOffsetTable(chunk, size, | |
| 8741 lastFreeRangeCoalesced()); | |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8742 } else if (CMSTraceSweeper) { |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8743 gclog_or_tty->print_cr("Already in free list: nothing to flush"); |
| 0 | 8744 } |
| 8745 set_inFreeRange(false); | |
| 8746 set_freeRangeInFreeLists(false); | |
| 8747 } | |
| 8748 | |
| 8749 // We take a break if we've been at this for a while, | |
| 8750 // so as to avoid monopolizing the locks involved. | |
| 8751 void SweepClosure::do_yield_work(HeapWord* addr) { | |
| 8752 // Return current free chunk being used for coalescing (if any) | |
| 8753 // to the appropriate freelist. After yielding, the next | |
| 8754 // free block encountered will start a coalescing range of | |
| 8755 // free blocks. If the next free block is adjacent to the | |
| 8756 // chunk just flushed, they will need to wait for the next | |
| 8757 // sweep to be coalesced. | |
| 8758 if (inFreeRange()) { | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8759 flush_cur_free_chunk(freeFinger(), pointer_delta(addr, freeFinger())); |
| 0 | 8760 } |
| 8761 | |
| 8762 // First give up the locks, then yield, then re-lock. | |
| 8763 // We should probably use a constructor/destructor idiom to | |
| 8764 // do this unlock/lock or modify the MutexUnlocker class to | |
| 8765 // serve our purpose. XXX | |
| 8766 assert_lock_strong(_bitMap->lock()); | |
| 8767 assert_lock_strong(_freelistLock); | |
| 8768 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 8769 "CMS thread should hold CMS token"); | |
| 8770 _bitMap->lock()->unlock(); | |
| 8771 _freelistLock->unlock(); | |
| 8772 ConcurrentMarkSweepThread::desynchronize(true); | |
| 8773 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 8774 _collector->stopTimer(); | |
| 8775 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 8776 if (PrintCMSStatistics != 0) { | |
| 8777 _collector->incrementYields(); | |
| 8778 } | |
| 8779 _collector->icms_wait(); | |
| 8780 | |
| 8781 // See the comment in coordinator_yield() | |
| 8782 for (unsigned i = 0; i < CMSYieldSleepCount && | |
| 8783 ConcurrentMarkSweepThread::should_yield() && | |
| 8784 !CMSCollector::foregroundGCIsActive(); ++i) { | |
| 8785 os::sleep(Thread::current(), 1, false); | |
| 8786 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 8787 } | |
| 8788 | |
| 8789 ConcurrentMarkSweepThread::synchronize(true); | |
| 8790 _freelistLock->lock(); | |
| 8791 _bitMap->lock()->lock_without_safepoint_check(); | |
| 8792 _collector->startTimer(); | |
| 8793 } | |
| 8794 | |
| 8795 #ifndef PRODUCT | |
| 8796 // This is actually very useful in a product build if it can | |
| 8797 // be called from the debugger. Compile it into the product | |
| 8798 // as needed. | |
|
6028
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
parents:
6026
diff
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|
8799 bool debug_verify_chunk_in_free_list(FreeChunk* fc) { |
|
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
parents:
6026
diff
changeset
|
8800 return debug_cms_space->verify_chunk_in_free_list(fc); |
| 0 | 8801 } |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8802 #endif |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8803 |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8804 void SweepClosure::print_free_block_coalesced(FreeChunk* fc) const { |
| 0 | 8805 if (CMSTraceSweeper) { |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8806 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
|
8807 fc, fc->size()); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8808 } |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8809 } |
| 0 | 8810 |
| 8811 // CMSIsAliveClosure | |
| 8812 bool CMSIsAliveClosure::do_object_b(oop obj) { | |
| 8813 HeapWord* addr = (HeapWord*)obj; | |
| 8814 return addr != NULL && | |
| 8815 (!_span.contains(addr) || _bit_map->isMarked(addr)); | |
| 8816 } | |
| 8817 | |
|
6725
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
8818 |
| 935 | 8819 CMSKeepAliveClosure::CMSKeepAliveClosure( CMSCollector* collector, |
| 8820 MemRegion span, | |
| 8821 CMSBitMap* bit_map, CMSMarkStack* mark_stack, | |
|
6725
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
8822 bool cpc): |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
8823 _collector(collector), |
| 935 | 8824 _span(span), |
| 8825 _bit_map(bit_map), | |
| 8826 _mark_stack(mark_stack), | |
| 8827 _concurrent_precleaning(cpc) { | |
| 8828 assert(!_span.is_empty(), "Empty span could spell trouble"); | |
| 8829 } | |
| 8830 | |
| 8831 | |
| 0 | 8832 // CMSKeepAliveClosure: the serial version |
|
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
8833 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
|
8834 HeapWord* addr = (HeapWord*)obj; |
| 0 | 8835 if (_span.contains(addr) && |
| 8836 !_bit_map->isMarked(addr)) { | |
| 8837 _bit_map->mark(addr); | |
| 8838 bool simulate_overflow = false; | |
| 8839 NOT_PRODUCT( | |
| 8840 if (CMSMarkStackOverflowALot && | |
| 8841 _collector->simulate_overflow()) { | |
| 8842 // simulate a stack overflow | |
| 8843 simulate_overflow = true; | |
| 8844 } | |
| 8845 ) | |
|
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
8846 if (simulate_overflow || !_mark_stack->push(obj)) { |
|
452
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
8847 if (_concurrent_precleaning) { |
|
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
8848 // We dirty the overflown object and let the remark |
|
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
8849 // phase deal with it. |
|
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
8850 assert(_collector->overflow_list_is_empty(), "Error"); |
|
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
8851 // In the case of object arrays, we need to dirty all of |
|
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
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360
diff
changeset
|
8852 // the cards that the object spans. No locking or atomics |
|
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
8853 // are needed since no one else can be mutating the mod union |
|
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
8854 // table. |
|
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
8855 if (obj->is_objArray()) { |
|
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
8856 size_t sz = obj->size(); |
|
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
8857 HeapWord* end_card_addr = |
|
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
8858 (HeapWord*)round_to((intptr_t)(addr+sz), CardTableModRefBS::card_size); |
|
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
8859 MemRegion redirty_range = MemRegion(addr, end_card_addr); |
|
00b023ae2d78
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8860 assert(!redirty_range.is_empty(), "Arithmetical tautology"); |
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8861 _collector->_modUnionTable.mark_range(redirty_range); |
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8862 } else { |
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8863 _collector->_modUnionTable.mark(addr); |
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8864 } |
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8865 _collector->_ser_kac_preclean_ovflw++; |
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8866 } else { |
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8867 _collector->push_on_overflow_list(obj); |
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8868 _collector->_ser_kac_ovflw++; |
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8869 } |
| 0 | 8870 } |
| 8871 } | |
| 8872 } | |
| 8873 | |
|
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8874 void CMSKeepAliveClosure::do_oop(oop* p) { CMSKeepAliveClosure::do_oop_work(p); } |
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8875 void CMSKeepAliveClosure::do_oop(narrowOop* p) { CMSKeepAliveClosure::do_oop_work(p); } |
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8876 |
| 0 | 8877 // CMSParKeepAliveClosure: a parallel version of the above. |
| 8878 // The work queues are private to each closure (thread), | |
| 8879 // but (may be) available for stealing by other threads. | |
|
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8880 void CMSParKeepAliveClosure::do_oop(oop obj) { |
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8881 HeapWord* addr = (HeapWord*)obj; |
| 0 | 8882 if (_span.contains(addr) && |
| 8883 !_bit_map->isMarked(addr)) { | |
| 8884 // In general, during recursive tracing, several threads | |
| 8885 // may be concurrently getting here; the first one to | |
| 8886 // "tag" it, claims it. | |
| 8887 if (_bit_map->par_mark(addr)) { | |
|
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8888 bool res = _work_queue->push(obj); |
| 0 | 8889 assert(res, "Low water mark should be much less than capacity"); |
| 8890 // Do a recursive trim in the hope that this will keep | |
| 8891 // stack usage lower, but leave some oops for potential stealers | |
| 8892 trim_queue(_low_water_mark); | |
| 8893 } // Else, another thread got there first | |
| 8894 } | |
| 8895 } | |
| 8896 | |
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8897 void CMSParKeepAliveClosure::do_oop(oop* p) { CMSParKeepAliveClosure::do_oop_work(p); } |
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8898 void CMSParKeepAliveClosure::do_oop(narrowOop* p) { CMSParKeepAliveClosure::do_oop_work(p); } |
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8899 |
| 0 | 8900 void CMSParKeepAliveClosure::trim_queue(uint max) { |
| 8901 while (_work_queue->size() > max) { | |
| 8902 oop new_oop; | |
| 8903 if (_work_queue->pop_local(new_oop)) { | |
| 8904 assert(new_oop != NULL && new_oop->is_oop(), "Expected an oop"); | |
| 8905 assert(_bit_map->isMarked((HeapWord*)new_oop), | |
| 8906 "no white objects on this stack!"); | |
| 8907 assert(_span.contains((HeapWord*)new_oop), "Out of bounds oop"); | |
| 8908 // iterate over the oops in this oop, marking and pushing | |
| 8909 // the ones in CMS heap (i.e. in _span). | |
| 8910 new_oop->oop_iterate(&_mark_and_push); | |
| 8911 } | |
| 8912 } | |
| 8913 } | |
| 8914 | |
| 935 | 8915 CMSInnerParMarkAndPushClosure::CMSInnerParMarkAndPushClosure( |
| 8916 CMSCollector* collector, | |
| 8917 MemRegion span, CMSBitMap* bit_map, | |
| 8918 OopTaskQueue* work_queue): | |
|
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8919 _collector(collector), |
| 935 | 8920 _span(span), |
| 8921 _bit_map(bit_map), | |
| 8922 _work_queue(work_queue) { } | |
| 8923 | |
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8924 void CMSInnerParMarkAndPushClosure::do_oop(oop obj) { |
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8925 HeapWord* addr = (HeapWord*)obj; |
| 0 | 8926 if (_span.contains(addr) && |
| 8927 !_bit_map->isMarked(addr)) { | |
| 8928 if (_bit_map->par_mark(addr)) { | |
| 8929 bool simulate_overflow = false; | |
| 8930 NOT_PRODUCT( | |
| 8931 if (CMSMarkStackOverflowALot && | |
| 8932 _collector->par_simulate_overflow()) { | |
| 8933 // simulate a stack overflow | |
| 8934 simulate_overflow = true; | |
| 8935 } | |
| 8936 ) | |
|
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8937 if (simulate_overflow || !_work_queue->push(obj)) { |
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8938 _collector->par_push_on_overflow_list(obj); |
| 0 | 8939 _collector->_par_kac_ovflw++; |
| 8940 } | |
| 8941 } // Else another thread got there already | |
| 8942 } | |
| 8943 } | |
| 8944 | |
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8945 void CMSInnerParMarkAndPushClosure::do_oop(oop* p) { CMSInnerParMarkAndPushClosure::do_oop_work(p); } |
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8946 void CMSInnerParMarkAndPushClosure::do_oop(narrowOop* p) { CMSInnerParMarkAndPushClosure::do_oop_work(p); } |
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8947 |
| 0 | 8948 ////////////////////////////////////////////////////////////////// |
| 8949 // CMSExpansionCause ///////////////////////////// | |
| 8950 ////////////////////////////////////////////////////////////////// | |
| 8951 const char* CMSExpansionCause::to_string(CMSExpansionCause::Cause cause) { | |
| 8952 switch (cause) { | |
| 8953 case _no_expansion: | |
| 8954 return "No expansion"; | |
| 8955 case _satisfy_free_ratio: | |
| 8956 return "Free ratio"; | |
| 8957 case _satisfy_promotion: | |
| 8958 return "Satisfy promotion"; | |
| 8959 case _satisfy_allocation: | |
| 8960 return "allocation"; | |
| 8961 case _allocate_par_lab: | |
| 8962 return "Par LAB"; | |
| 8963 case _allocate_par_spooling_space: | |
| 8964 return "Par Spooling Space"; | |
| 8965 case _adaptive_size_policy: | |
| 8966 return "Ergonomics"; | |
| 8967 default: | |
| 8968 return "unknown"; | |
| 8969 } | |
| 8970 } | |
| 8971 | |
| 8972 void CMSDrainMarkingStackClosure::do_void() { | |
| 8973 // the max number to take from overflow list at a time | |
| 8974 const size_t num = _mark_stack->capacity()/4; | |
|
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8975 assert(!_concurrent_precleaning || _collector->overflow_list_is_empty(), |
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8976 "Overflow list should be NULL during concurrent phases"); |
| 0 | 8977 while (!_mark_stack->isEmpty() || |
| 8978 // if stack is empty, check the overflow list | |
| 8979 _collector->take_from_overflow_list(num, _mark_stack)) { | |
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8980 oop obj = _mark_stack->pop(); |
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8981 HeapWord* addr = (HeapWord*)obj; |
| 0 | 8982 assert(_span.contains(addr), "Should be within span"); |
| 8983 assert(_bit_map->isMarked(addr), "Should be marked"); | |
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8984 assert(obj->is_oop(), "Should be an oop"); |
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8985 obj->oop_iterate(_keep_alive); |
| 0 | 8986 } |
| 8987 } | |
| 8988 | |
| 8989 void CMSParDrainMarkingStackClosure::do_void() { | |
| 8990 // drain queue | |
| 8991 trim_queue(0); | |
| 8992 } | |
| 8993 | |
| 8994 // Trim our work_queue so its length is below max at return | |
| 8995 void CMSParDrainMarkingStackClosure::trim_queue(uint max) { | |
| 8996 while (_work_queue->size() > max) { | |
| 8997 oop new_oop; | |
| 8998 if (_work_queue->pop_local(new_oop)) { | |
| 8999 assert(new_oop->is_oop(), "Expected an oop"); | |
| 9000 assert(_bit_map->isMarked((HeapWord*)new_oop), | |
| 9001 "no white objects on this stack!"); | |
| 9002 assert(_span.contains((HeapWord*)new_oop), "Out of bounds oop"); | |
| 9003 // iterate over the oops in this oop, marking and pushing | |
| 9004 // the ones in CMS heap (i.e. in _span). | |
| 9005 new_oop->oop_iterate(&_mark_and_push); | |
| 9006 } | |
| 9007 } | |
| 9008 } | |
| 9009 | |
| 9010 //////////////////////////////////////////////////////////////////// | |
| 9011 // Support for Marking Stack Overflow list handling and related code | |
| 9012 //////////////////////////////////////////////////////////////////// | |
| 9013 // Much of the following code is similar in shape and spirit to the | |
| 9014 // code used in ParNewGC. We should try and share that code | |
| 9015 // as much as possible in the future. | |
| 9016 | |
| 9017 #ifndef PRODUCT | |
| 9018 // Debugging support for CMSStackOverflowALot | |
| 9019 | |
| 9020 // It's OK to call this multi-threaded; the worst thing | |
| 9021 // that can happen is that we'll get a bunch of closely | |
| 14309 | 9022 // spaced simulated overflows, but that's OK, in fact |
| 0 | 9023 // probably good as it would exercise the overflow code |
| 9024 // under contention. | |
| 9025 bool CMSCollector::simulate_overflow() { | |
| 9026 if (_overflow_counter-- <= 0) { // just being defensive | |
| 9027 _overflow_counter = CMSMarkStackOverflowInterval; | |
| 9028 return true; | |
| 9029 } else { | |
| 9030 return false; | |
| 9031 } | |
| 9032 } | |
| 9033 | |
| 9034 bool CMSCollector::par_simulate_overflow() { | |
| 9035 return simulate_overflow(); | |
| 9036 } | |
| 9037 #endif | |
| 9038 | |
| 9039 // Single-threaded | |
| 9040 bool CMSCollector::take_from_overflow_list(size_t num, CMSMarkStack* stack) { | |
| 9041 assert(stack->isEmpty(), "Expected precondition"); | |
| 9042 assert(stack->capacity() > num, "Shouldn't bite more than can chew"); | |
| 9043 size_t i = num; | |
| 9044 oop cur = _overflow_list; | |
| 9045 const markOop proto = markOopDesc::prototype(); | |
| 534 | 9046 NOT_PRODUCT(ssize_t n = 0;) |
| 0 | 9047 for (oop next; i > 0 && cur != NULL; cur = next, i--) { |
| 9048 next = oop(cur->mark()); | |
| 9049 cur->set_mark(proto); // until proven otherwise | |
| 9050 assert(cur->is_oop(), "Should be an oop"); | |
| 9051 bool res = stack->push(cur); | |
| 9052 assert(res, "Bit off more than can chew?"); | |
| 9053 NOT_PRODUCT(n++;) | |
| 9054 } | |
| 9055 _overflow_list = cur; | |
| 9056 #ifndef PRODUCT | |
| 9057 assert(_num_par_pushes >= n, "Too many pops?"); | |
| 9058 _num_par_pushes -=n; | |
| 9059 #endif | |
| 9060 return !stack->isEmpty(); | |
| 9061 } | |
| 9062 | |
|
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9063 #define BUSY (cast_to_oop<intptr_t>(0x1aff1aff)) |
| 534 | 9064 // (MT-safe) Get a prefix of at most "num" from the list. |
| 9065 // The overflow list is chained through the mark word of | |
| 9066 // each object in the list. We fetch the entire list, | |
| 9067 // break off a prefix of the right size and return the | |
| 9068 // remainder. If other threads try to take objects from | |
| 9069 // the overflow list at that time, they will wait for | |
| 9070 // some time to see if data becomes available. If (and | |
| 9071 // only if) another thread places one or more object(s) | |
| 9072 // on the global list before we have returned the suffix | |
| 9073 // to the global list, we will walk down our local list | |
| 9074 // to find its end and append the global list to | |
| 9075 // our suffix before returning it. This suffix walk can | |
| 9076 // prove to be expensive (quadratic in the amount of traffic) | |
| 9077 // when there are many objects in the overflow list and | |
| 9078 // there is much producer-consumer contention on the list. | |
| 9079 // *NOTE*: The overflow list manipulation code here and | |
| 9080 // in ParNewGeneration:: are very similar in shape, | |
| 9081 // except that in the ParNew case we use the old (from/eden) | |
| 9082 // copy of the object to thread the list via its klass word. | |
| 9083 // Because of the common code, if you make any changes in | |
| 9084 // the code below, please check the ParNew version to see if | |
| 9085 // similar changes might be needed. | |
| 9086 // CR 6797058 has been filed to consolidate the common code. | |
| 0 | 9087 bool CMSCollector::par_take_from_overflow_list(size_t num, |
|
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9088 OopTaskQueue* work_q, |
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9089 int no_of_gc_threads) { |
| 534 | 9090 assert(work_q->size() == 0, "First empty local work queue"); |
| 0 | 9091 assert(num < work_q->max_elems(), "Can't bite more than we can chew"); |
| 9092 if (_overflow_list == NULL) { | |
| 9093 return false; | |
| 9094 } | |
| 9095 // Grab the entire list; we'll put back a suffix | |
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9096 oop prefix = cast_to_oop(Atomic::xchg_ptr(BUSY, &_overflow_list)); |
| 534 | 9097 Thread* tid = Thread::current(); |
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9098 // Before "no_of_gc_threads" was introduced CMSOverflowSpinCount was |
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9099 // set to ParallelGCThreads. |
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9100 size_t CMSOverflowSpinCount = (size_t) no_of_gc_threads; // was ParallelGCThreads; |
| 534 | 9101 size_t sleep_time_millis = MAX2((size_t)1, num/100); |
| 9102 // If the list is busy, we spin for a short while, | |
| 9103 // sleeping between attempts to get the list. | |
| 9104 for (size_t spin = 0; prefix == BUSY && spin < CMSOverflowSpinCount; spin++) { | |
| 9105 os::sleep(tid, sleep_time_millis, false); | |
| 9106 if (_overflow_list == NULL) { | |
| 9107 // Nothing left to take | |
| 9108 return false; | |
| 9109 } else if (_overflow_list != BUSY) { | |
| 9110 // Try and grab the prefix | |
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9111 prefix = cast_to_oop(Atomic::xchg_ptr(BUSY, &_overflow_list)); |
| 534 | 9112 } |
| 9113 } | |
| 9114 // If the list was found to be empty, or we spun long | |
| 9115 // enough, we give up and return empty-handed. If we leave | |
| 9116 // the list in the BUSY state below, it must be the case that | |
| 9117 // some other thread holds the overflow list and will set it | |
| 9118 // to a non-BUSY state in the future. | |
| 9119 if (prefix == NULL || prefix == BUSY) { | |
| 9120 // Nothing to take or waited long enough | |
| 9121 if (prefix == NULL) { | |
| 9122 // Write back the NULL in case we overwrote it with BUSY above | |
| 9123 // and it is still the same value. | |
| 9124 (void) Atomic::cmpxchg_ptr(NULL, &_overflow_list, BUSY); | |
| 9125 } | |
| 9126 return false; | |
| 9127 } | |
| 9128 assert(prefix != NULL && prefix != BUSY, "Error"); | |
| 0 | 9129 size_t i = num; |
| 9130 oop cur = prefix; | |
| 534 | 9131 // Walk down the first "num" objects, unless we reach the end. |
| 0 | 9132 for (; i > 1 && cur->mark() != NULL; cur = oop(cur->mark()), i--); |
| 534 | 9133 if (cur->mark() == NULL) { |
| 9134 // We have "num" or fewer elements in the list, so there | |
| 9135 // is nothing to return to the global list. | |
| 9136 // Write back the NULL in lieu of the BUSY we wrote | |
| 9137 // above, if it is still the same value. | |
| 9138 if (_overflow_list == BUSY) { | |
| 9139 (void) Atomic::cmpxchg_ptr(NULL, &_overflow_list, BUSY); | |
| 9140 } | |
| 9141 } else { | |
| 14309 | 9142 // Chop off the suffix and return it to the global list. |
| 534 | 9143 assert(cur->mark() != BUSY, "Error"); |
| 0 | 9144 oop suffix_head = cur->mark(); // suffix will be put back on global list |
| 9145 cur->set_mark(NULL); // break off suffix | |
| 534 | 9146 // It's possible that the list is still in the empty(busy) state |
| 9147 // we left it in a short while ago; in that case we may be | |
| 9148 // able to place back the suffix without incurring the cost | |
| 9149 // of a walk down the list. | |
| 0 | 9150 oop observed_overflow_list = _overflow_list; |
| 534 | 9151 oop cur_overflow_list = observed_overflow_list; |
| 9152 bool attached = false; | |
| 9153 while (observed_overflow_list == BUSY || observed_overflow_list == NULL) { | |
| 0 | 9154 observed_overflow_list = |
| 534 | 9155 (oop) Atomic::cmpxchg_ptr(suffix_head, &_overflow_list, cur_overflow_list); |
| 9156 if (cur_overflow_list == observed_overflow_list) { | |
| 9157 attached = true; | |
| 9158 break; | |
| 9159 } else cur_overflow_list = observed_overflow_list; | |
| 9160 } | |
| 9161 if (!attached) { | |
| 9162 // Too bad, someone else sneaked in (at least) an element; we'll need | |
| 9163 // to do a splice. Find tail of suffix so we can prepend suffix to global | |
| 9164 // list. | |
| 9165 for (cur = suffix_head; cur->mark() != NULL; cur = (oop)(cur->mark())); | |
| 9166 oop suffix_tail = cur; | |
| 9167 assert(suffix_tail != NULL && suffix_tail->mark() == NULL, | |
| 9168 "Tautology"); | |
| 9169 observed_overflow_list = _overflow_list; | |
| 9170 do { | |
| 9171 cur_overflow_list = observed_overflow_list; | |
| 9172 if (cur_overflow_list != BUSY) { | |
| 9173 // Do the splice ... | |
| 9174 suffix_tail->set_mark(markOop(cur_overflow_list)); | |
| 9175 } else { // cur_overflow_list == BUSY | |
| 9176 suffix_tail->set_mark(NULL); | |
| 9177 } | |
| 9178 // ... and try to place spliced list back on overflow_list ... | |
| 9179 observed_overflow_list = | |
| 9180 (oop) Atomic::cmpxchg_ptr(suffix_head, &_overflow_list, cur_overflow_list); | |
| 9181 } while (cur_overflow_list != observed_overflow_list); | |
| 9182 // ... until we have succeeded in doing so. | |
| 9183 } | |
| 0 | 9184 } |
| 9185 | |
| 9186 // Push the prefix elements on work_q | |
| 9187 assert(prefix != NULL, "control point invariant"); | |
| 9188 const markOop proto = markOopDesc::prototype(); | |
| 9189 oop next; | |
| 534 | 9190 NOT_PRODUCT(ssize_t n = 0;) |
| 0 | 9191 for (cur = prefix; cur != NULL; cur = next) { |
| 9192 next = oop(cur->mark()); | |
| 9193 cur->set_mark(proto); // until proven otherwise | |
| 9194 assert(cur->is_oop(), "Should be an oop"); | |
| 9195 bool res = work_q->push(cur); | |
| 9196 assert(res, "Bit off more than we can chew?"); | |
| 9197 NOT_PRODUCT(n++;) | |
| 9198 } | |
| 9199 #ifndef PRODUCT | |
| 9200 assert(_num_par_pushes >= n, "Too many pops?"); | |
| 9201 Atomic::add_ptr(-(intptr_t)n, &_num_par_pushes); | |
| 9202 #endif | |
| 9203 return true; | |
| 9204 } | |
| 9205 | |
| 9206 // Single-threaded | |
| 9207 void CMSCollector::push_on_overflow_list(oop p) { | |
| 9208 NOT_PRODUCT(_num_par_pushes++;) | |
| 9209 assert(p->is_oop(), "Not an oop"); | |
| 9210 preserve_mark_if_necessary(p); | |
| 9211 p->set_mark((markOop)_overflow_list); | |
| 9212 _overflow_list = p; | |
| 9213 } | |
| 9214 | |
| 9215 // Multi-threaded; use CAS to prepend to overflow list | |
| 9216 void CMSCollector::par_push_on_overflow_list(oop p) { | |
| 9217 NOT_PRODUCT(Atomic::inc_ptr(&_num_par_pushes);) | |
| 9218 assert(p->is_oop(), "Not an oop"); | |
| 9219 par_preserve_mark_if_necessary(p); | |
| 9220 oop observed_overflow_list = _overflow_list; | |
| 9221 oop cur_overflow_list; | |
| 9222 do { | |
| 9223 cur_overflow_list = observed_overflow_list; | |
| 534 | 9224 if (cur_overflow_list != BUSY) { |
| 9225 p->set_mark(markOop(cur_overflow_list)); | |
| 9226 } else { | |
| 9227 p->set_mark(NULL); | |
| 9228 } | |
| 0 | 9229 observed_overflow_list = |
| 9230 (oop) Atomic::cmpxchg_ptr(p, &_overflow_list, cur_overflow_list); | |
| 9231 } while (cur_overflow_list != observed_overflow_list); | |
| 9232 } | |
| 534 | 9233 #undef BUSY |
| 0 | 9234 |
| 9235 // Single threaded | |
| 9236 // General Note on GrowableArray: pushes may silently fail | |
| 9237 // because we are (temporarily) out of C-heap for expanding | |
| 9238 // the stack. The problem is quite ubiquitous and affects | |
| 9239 // a lot of code in the JVM. The prudent thing for GrowableArray | |
| 9240 // to do (for now) is to exit with an error. However, that may | |
| 9241 // be too draconian in some cases because the caller may be | |
| 534 | 9242 // able to recover without much harm. For such cases, we |
| 0 | 9243 // should probably introduce a "soft_push" method which returns |
| 9244 // an indication of success or failure with the assumption that | |
| 9245 // the caller may be able to recover from a failure; code in | |
| 9246 // the VM can then be changed, incrementally, to deal with such | |
| 9247 // failures where possible, thus, incrementally hardening the VM | |
| 9248 // in such low resource situations. | |
| 9249 void CMSCollector::preserve_mark_work(oop p, markOop m) { | |
|
1836
894b1d7c7e01
6423256: GC stacks should use a better data structure
jcoomes
parents:
1833
diff
changeset
|
9250 _preserved_oop_stack.push(p); |
|
894b1d7c7e01
6423256: GC stacks should use a better data structure
jcoomes
parents:
1833
diff
changeset
|
9251 _preserved_mark_stack.push(m); |
| 0 | 9252 assert(m == p->mark(), "Mark word changed"); |
|
1836
894b1d7c7e01
6423256: GC stacks should use a better data structure
jcoomes
parents:
1833
diff
changeset
|
9253 assert(_preserved_oop_stack.size() == _preserved_mark_stack.size(), |
| 0 | 9254 "bijection"); |
| 9255 } | |
| 9256 | |
| 9257 // Single threaded | |
| 9258 void CMSCollector::preserve_mark_if_necessary(oop p) { | |
| 9259 markOop m = p->mark(); | |
| 9260 if (m->must_be_preserved(p)) { | |
| 9261 preserve_mark_work(p, m); | |
| 9262 } | |
| 9263 } | |
| 9264 | |
| 9265 void CMSCollector::par_preserve_mark_if_necessary(oop p) { | |
| 9266 markOop m = p->mark(); | |
| 9267 if (m->must_be_preserved(p)) { | |
| 9268 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); | |
| 9269 // Even though we read the mark word without holding | |
| 9270 // the lock, we are assured that it will not change | |
| 9271 // because we "own" this oop, so no other thread can | |
| 9272 // be trying to push it on the overflow list; see | |
| 9273 // the assertion in preserve_mark_work() that checks | |
| 9274 // that m == p->mark(). | |
| 9275 preserve_mark_work(p, m); | |
| 9276 } | |
| 9277 } | |
| 9278 | |
| 9279 // We should be able to do this multi-threaded, | |
| 9280 // a chunk of stack being a task (this is | |
| 9281 // correct because each oop only ever appears | |
| 9282 // once in the overflow list. However, it's | |
| 9283 // not very easy to completely overlap this with | |
| 9284 // other operations, so will generally not be done | |
| 9285 // until all work's been completed. Because we | |
| 9286 // expect the preserved oop stack (set) to be small, | |
| 9287 // it's probably fine to do this single-threaded. | |
| 9288 // We can explore cleverer concurrent/overlapped/parallel | |
| 9289 // processing of preserved marks if we feel the | |
| 9290 // need for this in the future. Stack overflow should | |
| 9291 // be so rare in practice and, when it happens, its | |
| 9292 // effect on performance so great that this will | |
| 9293 // likely just be in the noise anyway. | |
| 9294 void CMSCollector::restore_preserved_marks_if_any() { | |
| 9295 assert(SafepointSynchronize::is_at_safepoint(), | |
| 9296 "world should be stopped"); | |
| 9297 assert(Thread::current()->is_ConcurrentGC_thread() || | |
| 9298 Thread::current()->is_VM_thread(), | |
| 9299 "should be single-threaded"); | |
|
1836
894b1d7c7e01
6423256: GC stacks should use a better data structure
jcoomes
parents:
1833
diff
changeset
|
9300 assert(_preserved_oop_stack.size() == _preserved_mark_stack.size(), |
|
894b1d7c7e01
6423256: GC stacks should use a better data structure
jcoomes
parents:
1833
diff
changeset
|
9301 "bijection"); |
|
894b1d7c7e01
6423256: GC stacks should use a better data structure
jcoomes
parents:
1833
diff
changeset
|
9302 |
|
894b1d7c7e01
6423256: GC stacks should use a better data structure
jcoomes
parents:
1833
diff
changeset
|
9303 while (!_preserved_oop_stack.is_empty()) { |
|
894b1d7c7e01
6423256: GC stacks should use a better data structure
jcoomes
parents:
1833
diff
changeset
|
9304 oop p = _preserved_oop_stack.pop(); |
| 0 | 9305 assert(p->is_oop(), "Should be an oop"); |
| 9306 assert(_span.contains(p), "oop should be in _span"); | |
| 9307 assert(p->mark() == markOopDesc::prototype(), | |
| 9308 "Set when taken from overflow list"); | |
|
1836
894b1d7c7e01
6423256: GC stacks should use a better data structure
jcoomes
parents:
1833
diff
changeset
|
9309 markOop m = _preserved_mark_stack.pop(); |
| 0 | 9310 p->set_mark(m); |
| 9311 } | |
|
1836
894b1d7c7e01
6423256: GC stacks should use a better data structure
jcoomes
parents:
1833
diff
changeset
|
9312 assert(_preserved_mark_stack.is_empty() && _preserved_oop_stack.is_empty(), |
| 0 | 9313 "stacks were cleared above"); |
| 9314 } | |
| 9315 | |
| 9316 #ifndef PRODUCT | |
| 9317 bool CMSCollector::no_preserved_marks() const { | |
|
1836
894b1d7c7e01
6423256: GC stacks should use a better data structure
jcoomes
parents:
1833
diff
changeset
|
9318 return _preserved_mark_stack.is_empty() && _preserved_oop_stack.is_empty(); |
| 0 | 9319 } |
| 9320 #endif | |
| 9321 | |
| 9322 CMSAdaptiveSizePolicy* ASConcurrentMarkSweepGeneration::cms_size_policy() const | |
| 9323 { | |
| 9324 GenCollectedHeap* gch = (GenCollectedHeap*) GenCollectedHeap::heap(); | |
| 9325 CMSAdaptiveSizePolicy* size_policy = | |
| 9326 (CMSAdaptiveSizePolicy*) gch->gen_policy()->size_policy(); | |
| 9327 assert(size_policy->is_gc_cms_adaptive_size_policy(), | |
| 9328 "Wrong type for size policy"); | |
| 9329 return size_policy; | |
| 9330 } | |
| 9331 | |
| 9332 void ASConcurrentMarkSweepGeneration::resize(size_t cur_promo_size, | |
| 9333 size_t desired_promo_size) { | |
| 9334 if (cur_promo_size < desired_promo_size) { | |
| 9335 size_t expand_bytes = desired_promo_size - cur_promo_size; | |
| 9336 if (PrintAdaptiveSizePolicy && Verbose) { | |
| 9337 gclog_or_tty->print_cr(" ASConcurrentMarkSweepGeneration::resize " | |
| 9338 "Expanding tenured generation by " SIZE_FORMAT " (bytes)", | |
| 9339 expand_bytes); | |
| 9340 } | |
| 9341 expand(expand_bytes, | |
| 9342 MinHeapDeltaBytes, | |
| 9343 CMSExpansionCause::_adaptive_size_policy); | |
| 9344 } else if (desired_promo_size < cur_promo_size) { | |
| 9345 size_t shrink_bytes = cur_promo_size - desired_promo_size; | |
| 9346 if (PrintAdaptiveSizePolicy && Verbose) { | |
| 9347 gclog_or_tty->print_cr(" ASConcurrentMarkSweepGeneration::resize " | |
| 9348 "Shrinking tenured generation by " SIZE_FORMAT " (bytes)", | |
| 9349 shrink_bytes); | |
| 9350 } | |
| 9351 shrink(shrink_bytes); | |
| 9352 } | |
| 9353 } | |
| 9354 | |
| 9355 CMSGCAdaptivePolicyCounters* ASConcurrentMarkSweepGeneration::gc_adaptive_policy_counters() { | |
| 9356 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 9357 CMSGCAdaptivePolicyCounters* counters = | |
| 9358 (CMSGCAdaptivePolicyCounters*) gch->collector_policy()->counters(); | |
| 9359 assert(counters->kind() == GCPolicyCounters::CMSGCAdaptivePolicyCountersKind, | |
| 9360 "Wrong kind of counters"); | |
| 9361 return counters; | |
| 9362 } | |
| 9363 | |
| 9364 | |
| 9365 void ASConcurrentMarkSweepGeneration::update_counters() { | |
| 9366 if (UsePerfData) { | |
| 9367 _space_counters->update_all(); | |
| 9368 _gen_counters->update_all(); | |
| 9369 CMSGCAdaptivePolicyCounters* counters = gc_adaptive_policy_counters(); | |
| 9370 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 9371 CMSGCStats* gc_stats_l = (CMSGCStats*) gc_stats(); | |
| 9372 assert(gc_stats_l->kind() == GCStats::CMSGCStatsKind, | |
| 9373 "Wrong gc statistics type"); | |
| 9374 counters->update_counters(gc_stats_l); | |
| 9375 } | |
| 9376 } | |
| 9377 | |
| 9378 void ASConcurrentMarkSweepGeneration::update_counters(size_t used) { | |
| 9379 if (UsePerfData) { | |
| 9380 _space_counters->update_used(used); | |
| 9381 _space_counters->update_capacity(); | |
| 9382 _gen_counters->update_all(); | |
| 9383 | |
| 9384 CMSGCAdaptivePolicyCounters* counters = gc_adaptive_policy_counters(); | |
| 9385 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 9386 CMSGCStats* gc_stats_l = (CMSGCStats*) gc_stats(); | |
| 9387 assert(gc_stats_l->kind() == GCStats::CMSGCStatsKind, | |
| 9388 "Wrong gc statistics type"); | |
| 9389 counters->update_counters(gc_stats_l); | |
| 9390 } | |
| 9391 } | |
| 9392 | |
| 9393 void ASConcurrentMarkSweepGeneration::shrink_by(size_t desired_bytes) { | |
| 9394 assert_locked_or_safepoint(Heap_lock); | |
| 9395 assert_lock_strong(freelistLock()); | |
| 9396 HeapWord* old_end = _cmsSpace->end(); | |
| 9397 HeapWord* unallocated_start = _cmsSpace->unallocated_block(); | |
| 9398 assert(old_end >= unallocated_start, "Miscalculation of unallocated_start"); | |
| 9399 FreeChunk* chunk_at_end = find_chunk_at_end(); | |
| 9400 if (chunk_at_end == NULL) { | |
| 9401 // No room to shrink | |
| 9402 if (PrintGCDetails && Verbose) { | |
| 9403 gclog_or_tty->print_cr("No room to shrink: old_end " | |
| 9404 PTR_FORMAT " unallocated_start " PTR_FORMAT | |
| 9405 " chunk_at_end " PTR_FORMAT, | |
| 9406 old_end, unallocated_start, chunk_at_end); | |
| 9407 } | |
| 9408 return; | |
| 9409 } else { | |
| 9410 | |
| 9411 // Find the chunk at the end of the space and determine | |
| 9412 // how much it can be shrunk. | |
| 9413 size_t shrinkable_size_in_bytes = chunk_at_end->size(); | |
| 9414 size_t aligned_shrinkable_size_in_bytes = | |
| 9415 align_size_down(shrinkable_size_in_bytes, os::vm_page_size()); | |
| 6885 | 9416 assert(unallocated_start <= (HeapWord*) chunk_at_end->end(), |
| 0 | 9417 "Inconsistent chunk at end of space"); |
| 9418 size_t bytes = MIN2(desired_bytes, aligned_shrinkable_size_in_bytes); | |
| 9419 size_t word_size_before = heap_word_size(_virtual_space.committed_size()); | |
| 9420 | |
| 9421 // Shrink the underlying space | |
| 9422 _virtual_space.shrink_by(bytes); | |
| 9423 if (PrintGCDetails && Verbose) { | |
| 9424 gclog_or_tty->print_cr("ConcurrentMarkSweepGeneration::shrink_by:" | |
| 9425 " desired_bytes " SIZE_FORMAT | |
| 9426 " shrinkable_size_in_bytes " SIZE_FORMAT | |
| 9427 " aligned_shrinkable_size_in_bytes " SIZE_FORMAT | |
| 9428 " bytes " SIZE_FORMAT, | |
| 9429 desired_bytes, shrinkable_size_in_bytes, | |
| 9430 aligned_shrinkable_size_in_bytes, bytes); | |
| 9431 gclog_or_tty->print_cr(" old_end " SIZE_FORMAT | |
| 9432 " unallocated_start " SIZE_FORMAT, | |
| 9433 old_end, unallocated_start); | |
| 9434 } | |
| 9435 | |
| 9436 // If the space did shrink (shrinking is not guaranteed), | |
| 9437 // shrink the chunk at the end by the appropriate amount. | |
| 9438 if (((HeapWord*)_virtual_space.high()) < old_end) { | |
| 9439 size_t new_word_size = | |
| 9440 heap_word_size(_virtual_space.committed_size()); | |
| 9441 | |
| 9442 // Have to remove the chunk from the dictionary because it is changing | |
| 9443 // size and might be someplace elsewhere in the dictionary. | |
| 9444 | |
| 9445 // Get the chunk at end, shrink it, and put it | |
| 9446 // back. | |
| 9447 _cmsSpace->removeChunkFromDictionary(chunk_at_end); | |
| 9448 size_t word_size_change = word_size_before - new_word_size; | |
| 9449 size_t chunk_at_end_old_size = chunk_at_end->size(); | |
| 9450 assert(chunk_at_end_old_size >= word_size_change, | |
| 9451 "Shrink is too large"); | |
|
6028
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
parents:
6026
diff
changeset
|
9452 chunk_at_end->set_size(chunk_at_end_old_size - |
| 0 | 9453 word_size_change); |
| 9454 _cmsSpace->freed((HeapWord*) chunk_at_end->end(), | |
| 9455 word_size_change); | |
| 9456 | |
| 9457 _cmsSpace->returnChunkToDictionary(chunk_at_end); | |
| 9458 | |
| 9459 MemRegion mr(_cmsSpace->bottom(), new_word_size); | |
| 9460 _bts->resize(new_word_size); // resize the block offset shared array | |
| 9461 Universe::heap()->barrier_set()->resize_covered_region(mr); | |
| 9462 _cmsSpace->assert_locked(); | |
| 9463 _cmsSpace->set_end((HeapWord*)_virtual_space.high()); | |
| 9464 | |
| 9465 NOT_PRODUCT(_cmsSpace->dictionary()->verify()); | |
| 9466 | |
| 9467 // update the space and generation capacity counters | |
| 9468 if (UsePerfData) { | |
| 9469 _space_counters->update_capacity(); | |
| 9470 _gen_counters->update_all(); | |
| 9471 } | |
| 9472 | |
| 9473 if (Verbose && PrintGCDetails) { | |
| 9474 size_t new_mem_size = _virtual_space.committed_size(); | |
| 9475 size_t old_mem_size = new_mem_size + bytes; | |
|
7623
203f64878aab
7102489: RFE: cleanup jlong typedef on __APPLE__and _LLP64 systems.
hseigel
parents:
6885
diff
changeset
|
9476 gclog_or_tty->print_cr("Shrinking %s from " SIZE_FORMAT "K by " SIZE_FORMAT "K to " SIZE_FORMAT "K", |
| 0 | 9477 name(), old_mem_size/K, bytes/K, new_mem_size/K); |
| 9478 } | |
| 9479 } | |
| 9480 | |
| 9481 assert(_cmsSpace->unallocated_block() <= _cmsSpace->end(), | |
| 9482 "Inconsistency at end of space"); | |
| 6885 | 9483 assert(chunk_at_end->end() == (uintptr_t*) _cmsSpace->end(), |
| 0 | 9484 "Shrinking is inconsistent"); |
| 9485 return; | |
| 9486 } | |
| 9487 } | |
| 9488 // Transfer some number of overflown objects to usual marking | |
| 9489 // stack. Return true if some objects were transferred. | |
| 9490 bool MarkRefsIntoAndScanClosure::take_from_overflow_list() { | |
|
679
cea947c8a988
6819891: ParNew: Fix work queue overflow code to deal correctly with +UseCompressedOops
ysr
parents:
628
diff
changeset
|
9491 size_t num = MIN2((size_t)(_mark_stack->capacity() - _mark_stack->length())/4, |
| 0 | 9492 (size_t)ParGCDesiredObjsFromOverflowList); |
| 9493 | |
| 9494 bool res = _collector->take_from_overflow_list(num, _mark_stack); | |
| 9495 assert(_collector->overflow_list_is_empty() || res, | |
| 9496 "If list is not empty, we should have taken something"); | |
| 9497 assert(!res || !_mark_stack->isEmpty(), | |
| 9498 "If we took something, it should now be on our stack"); | |
| 9499 return res; | |
| 9500 } | |
| 9501 | |
| 9502 size_t MarkDeadObjectsClosure::do_blk(HeapWord* addr) { | |
| 9503 size_t res = _sp->block_size_no_stall(addr, _collector); | |
| 9504 if (_sp->block_is_obj(addr)) { | |
| 9505 if (_live_bit_map->isMarked(addr)) { | |
| 9506 // It can't have been dead in a previous cycle | |
| 9507 guarantee(!_dead_bit_map->isMarked(addr), "No resurrection!"); | |
| 9508 } else { | |
| 9509 _dead_bit_map->mark(addr); // mark the dead object | |
| 9510 } | |
| 9511 } | |
|
2226
c5a923563727
6912621: iCMS: Error: assert(_markBitMap.isMarked(addr + 1),"Missing Printezis bit?")
ysr
parents:
2177
diff
changeset
|
9512 // Could be 0, if the block size could not be computed without stalling. |
| 0 | 9513 return res; |
| 9514 } | |
|
1703
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9515 |
|
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
parents:
3293
diff
changeset
|
9516 TraceCMSMemoryManagerStats::TraceCMSMemoryManagerStats(CMSCollector::CollectorState phase, GCCause::Cause cause): TraceMemoryManagerStats() { |
|
1703
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9517 |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9518 switch (phase) { |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9519 case CMSCollector::InitialMarking: |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9520 initialize(true /* fullGC */ , |
|
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
parents:
3293
diff
changeset
|
9521 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
|
9522 true /* recordGCBeginTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9523 true /* recordPreGCUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9524 false /* recordPeakUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9525 false /* recordPostGCusage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9526 true /* recordAccumulatedGCTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9527 false /* recordGCEndTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9528 false /* countCollection */ ); |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9529 break; |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9530 |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9531 case CMSCollector::FinalMarking: |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9532 initialize(true /* fullGC */ , |
|
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
parents:
3293
diff
changeset
|
9533 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
|
9534 false /* recordGCBeginTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9535 false /* recordPreGCUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9536 false /* recordPeakUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9537 false /* recordPostGCusage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9538 true /* recordAccumulatedGCTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9539 false /* recordGCEndTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9540 false /* countCollection */ ); |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9541 break; |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9542 |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9543 case CMSCollector::Sweeping: |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9544 initialize(true /* fullGC */ , |
|
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
parents:
3293
diff
changeset
|
9545 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
|
9546 false /* recordGCBeginTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9547 false /* recordPreGCUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9548 true /* recordPeakUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9549 true /* recordPostGCusage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9550 false /* recordAccumulatedGCTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9551 true /* recordGCEndTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9552 true /* countCollection */ ); |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9553 break; |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9554 |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9555 default: |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9556 ShouldNotReachHere(); |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9557 } |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9558 } |