Mercurial > hg > graal-compiler
annotate src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp @ 10180:ebded0261dfc
8012111: Remove warning about CMS generation shrinking.
Reviewed-by: johnc, brutisso, stefank
| author | jmasa |
|---|---|
| date | Mon, 22 Apr 2013 22:00:03 -0700 |
| parents | f36e073d56a4 |
| children | b06ac540229e |
| 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" | |
| 40 #include "gc_implementation/shared/isGCActiveMark.hpp" | |
| 41 #include "gc_interface/collectedHeap.inline.hpp" | |
| 42 #include "memory/cardTableRS.hpp" | |
| 43 #include "memory/collectorPolicy.hpp" | |
| 44 #include "memory/gcLocker.inline.hpp" | |
| 45 #include "memory/genCollectedHeap.hpp" | |
| 46 #include "memory/genMarkSweep.hpp" | |
| 47 #include "memory/genOopClosures.inline.hpp" | |
| 48 #include "memory/iterator.hpp" | |
| 49 #include "memory/referencePolicy.hpp" | |
| 50 #include "memory/resourceArea.hpp" | |
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51 #include "memory/tenuredGeneration.hpp" |
| 1972 | 52 #include "oops/oop.inline.hpp" |
| 53 #include "prims/jvmtiExport.hpp" | |
| 54 #include "runtime/globals_extension.hpp" | |
| 55 #include "runtime/handles.inline.hpp" | |
| 56 #include "runtime/java.hpp" | |
| 57 #include "runtime/vmThread.hpp" | |
| 58 #include "services/memoryService.hpp" | |
| 59 #include "services/runtimeService.hpp" | |
| 0 | 60 |
| 61 // statics | |
| 62 CMSCollector* ConcurrentMarkSweepGeneration::_collector = NULL; | |
| 63 bool CMSCollector::_full_gc_requested = false; | |
| 64 | |
| 65 ////////////////////////////////////////////////////////////////// | |
| 66 // In support of CMS/VM thread synchronization | |
| 67 ////////////////////////////////////////////////////////////////// | |
| 68 // We split use of the CGC_lock into 2 "levels". | |
| 69 // The low-level locking is of the usual CGC_lock monitor. We introduce | |
| 70 // a higher level "token" (hereafter "CMS token") built on top of the | |
| 71 // low level monitor (hereafter "CGC lock"). | |
| 72 // The token-passing protocol gives priority to the VM thread. The | |
| 73 // CMS-lock doesn't provide any fairness guarantees, but clients | |
| 74 // should ensure that it is only held for very short, bounded | |
| 75 // durations. | |
| 76 // | |
| 77 // When either of the CMS thread or the VM thread is involved in | |
| 78 // collection operations during which it does not want the other | |
| 79 // thread to interfere, it obtains the CMS token. | |
| 80 // | |
| 81 // If either thread tries to get the token while the other has | |
| 82 // it, that thread waits. However, if the VM thread and CMS thread | |
| 83 // both want the token, then the VM thread gets priority while the | |
| 84 // CMS thread waits. This ensures, for instance, that the "concurrent" | |
| 85 // phases of the CMS thread's work do not block out the VM thread | |
| 86 // for long periods of time as the CMS thread continues to hog | |
| 87 // the token. (See bug 4616232). | |
| 88 // | |
| 89 // The baton-passing functions are, however, controlled by the | |
| 90 // flags _foregroundGCShouldWait and _foregroundGCIsActive, | |
| 91 // and here the low-level CMS lock, not the high level token, | |
| 92 // ensures mutual exclusion. | |
| 93 // | |
| 94 // Two important conditions that we have to satisfy: | |
| 95 // 1. if a thread does a low-level wait on the CMS lock, then it | |
| 96 // relinquishes the CMS token if it were holding that token | |
| 97 // when it acquired the low-level CMS lock. | |
| 98 // 2. any low-level notifications on the low-level lock | |
| 99 // should only be sent when a thread has relinquished the token. | |
| 100 // | |
| 101 // In the absence of either property, we'd have potential deadlock. | |
| 102 // | |
| 103 // We protect each of the CMS (concurrent and sequential) phases | |
| 104 // with the CMS _token_, not the CMS _lock_. | |
| 105 // | |
| 106 // The only code protected by CMS lock is the token acquisition code | |
| 107 // itself, see ConcurrentMarkSweepThread::[de]synchronize(), and the | |
| 108 // baton-passing code. | |
| 109 // | |
| 110 // Unfortunately, i couldn't come up with a good abstraction to factor and | |
| 111 // hide the naked CGC_lock manipulation in the baton-passing code | |
| 112 // further below. That's something we should try to do. Also, the proof | |
| 113 // of correctness of this 2-level locking scheme is far from obvious, | |
| 114 // and potentially quite slippery. We have an uneasy supsicion, for instance, | |
| 115 // that there may be a theoretical possibility of delay/starvation in the | |
| 116 // low-level lock/wait/notify scheme used for the baton-passing because of | |
| 117 // potential intereference with the priority scheme embodied in the | |
| 118 // CMS-token-passing protocol. See related comments at a CGC_lock->wait() | |
| 119 // invocation further below and marked with "XXX 20011219YSR". | |
| 120 // Indeed, as we note elsewhere, this may become yet more slippery | |
| 121 // in the presence of multiple CMS and/or multiple VM threads. XXX | |
| 122 | |
| 123 class CMSTokenSync: public StackObj { | |
| 124 private: | |
| 125 bool _is_cms_thread; | |
| 126 public: | |
| 127 CMSTokenSync(bool is_cms_thread): | |
| 128 _is_cms_thread(is_cms_thread) { | |
| 129 assert(is_cms_thread == Thread::current()->is_ConcurrentGC_thread(), | |
| 130 "Incorrect argument to constructor"); | |
| 131 ConcurrentMarkSweepThread::synchronize(_is_cms_thread); | |
| 132 } | |
| 133 | |
| 134 ~CMSTokenSync() { | |
| 135 assert(_is_cms_thread ? | |
| 136 ConcurrentMarkSweepThread::cms_thread_has_cms_token() : | |
| 137 ConcurrentMarkSweepThread::vm_thread_has_cms_token(), | |
| 138 "Incorrect state"); | |
| 139 ConcurrentMarkSweepThread::desynchronize(_is_cms_thread); | |
| 140 } | |
| 141 }; | |
| 142 | |
| 143 // Convenience class that does a CMSTokenSync, and then acquires | |
| 144 // upto three locks. | |
| 145 class CMSTokenSyncWithLocks: public CMSTokenSync { | |
| 146 private: | |
| 147 // Note: locks are acquired in textual declaration order | |
| 148 // and released in the opposite order | |
| 149 MutexLockerEx _locker1, _locker2, _locker3; | |
| 150 public: | |
| 151 CMSTokenSyncWithLocks(bool is_cms_thread, Mutex* mutex1, | |
| 152 Mutex* mutex2 = NULL, Mutex* mutex3 = NULL): | |
| 153 CMSTokenSync(is_cms_thread), | |
| 154 _locker1(mutex1, Mutex::_no_safepoint_check_flag), | |
| 155 _locker2(mutex2, Mutex::_no_safepoint_check_flag), | |
| 156 _locker3(mutex3, Mutex::_no_safepoint_check_flag) | |
| 157 { } | |
| 158 }; | |
| 159 | |
| 160 | |
| 161 // Wrapper class to temporarily disable icms during a foreground cms collection. | |
| 162 class ICMSDisabler: public StackObj { | |
| 163 public: | |
| 164 // The ctor disables icms and wakes up the thread so it notices the change; | |
| 165 // the dtor re-enables icms. Note that the CMSCollector methods will check | |
| 166 // CMSIncrementalMode. | |
| 167 ICMSDisabler() { CMSCollector::disable_icms(); CMSCollector::start_icms(); } | |
| 168 ~ICMSDisabler() { CMSCollector::enable_icms(); } | |
| 169 }; | |
| 170 | |
| 171 ////////////////////////////////////////////////////////////////// | |
| 172 // Concurrent Mark-Sweep Generation ///////////////////////////// | |
| 173 ////////////////////////////////////////////////////////////////// | |
| 174 | |
| 175 NOT_PRODUCT(CompactibleFreeListSpace* debug_cms_space;) | |
| 176 | |
| 177 // This struct contains per-thread things necessary to support parallel | |
| 178 // young-gen collection. | |
| 6197 | 179 class CMSParGCThreadState: public CHeapObj<mtGC> { |
| 0 | 180 public: |
| 181 CFLS_LAB lab; | |
| 182 PromotionInfo promo; | |
| 183 | |
| 184 // Constructor. | |
| 185 CMSParGCThreadState(CompactibleFreeListSpace* cfls) : lab(cfls) { | |
| 186 promo.setSpace(cfls); | |
| 187 } | |
| 188 }; | |
| 189 | |
| 190 ConcurrentMarkSweepGeneration::ConcurrentMarkSweepGeneration( | |
| 191 ReservedSpace rs, size_t initial_byte_size, int level, | |
| 192 CardTableRS* ct, bool use_adaptive_freelists, | |
| 6026 | 193 FreeBlockDictionary<FreeChunk>::DictionaryChoice dictionaryChoice) : |
| 0 | 194 CardGeneration(rs, initial_byte_size, level, ct), |
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195 _dilatation_factor(((double)MinChunkSize)/((double)(CollectedHeap::min_fill_size()))), |
| 0 | 196 _debug_collection_type(Concurrent_collection_type) |
| 197 { | |
| 198 HeapWord* bottom = (HeapWord*) _virtual_space.low(); | |
| 199 HeapWord* end = (HeapWord*) _virtual_space.high(); | |
| 200 | |
| 201 _direct_allocated_words = 0; | |
| 202 NOT_PRODUCT( | |
| 203 _numObjectsPromoted = 0; | |
| 204 _numWordsPromoted = 0; | |
| 205 _numObjectsAllocated = 0; | |
| 206 _numWordsAllocated = 0; | |
| 207 ) | |
| 208 | |
| 209 _cmsSpace = new CompactibleFreeListSpace(_bts, MemRegion(bottom, end), | |
| 210 use_adaptive_freelists, | |
| 211 dictionaryChoice); | |
| 212 NOT_PRODUCT(debug_cms_space = _cmsSpace;) | |
| 213 if (_cmsSpace == NULL) { | |
| 214 vm_exit_during_initialization( | |
| 215 "CompactibleFreeListSpace allocation failure"); | |
| 216 } | |
| 217 _cmsSpace->_gen = this; | |
| 218 | |
| 219 _gc_stats = new CMSGCStats(); | |
| 220 | |
| 221 // Verify the assumption that FreeChunk::_prev and OopDesc::_klass | |
| 222 // offsets match. The ability to tell free chunks from objects | |
| 223 // depends on this property. | |
| 224 debug_only( | |
| 225 FreeChunk* junk = NULL; | |
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226 assert(UseCompressedKlassPointers || |
| 187 | 227 junk->prev_addr() == (void*)(oop(junk)->klass_addr()), |
| 0 | 228 "Offset of FreeChunk::_prev within FreeChunk must match" |
| 229 " that of OopDesc::_klass within OopDesc"); | |
| 230 ) | |
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231 if (CollectedHeap::use_parallel_gc_threads()) { |
| 0 | 232 typedef CMSParGCThreadState* CMSParGCThreadStatePtr; |
| 233 _par_gc_thread_states = | |
| 6197 | 234 NEW_C_HEAP_ARRAY(CMSParGCThreadStatePtr, ParallelGCThreads, mtGC); |
| 0 | 235 if (_par_gc_thread_states == NULL) { |
| 236 vm_exit_during_initialization("Could not allocate par gc structs"); | |
| 237 } | |
| 238 for (uint i = 0; i < ParallelGCThreads; i++) { | |
| 239 _par_gc_thread_states[i] = new CMSParGCThreadState(cmsSpace()); | |
| 240 if (_par_gc_thread_states[i] == NULL) { | |
| 241 vm_exit_during_initialization("Could not allocate par gc structs"); | |
| 242 } | |
| 243 } | |
| 244 } else { | |
| 245 _par_gc_thread_states = NULL; | |
| 246 } | |
| 247 _incremental_collection_failed = false; | |
| 248 // The "dilatation_factor" is the expansion that can occur on | |
| 249 // account of the fact that the minimum object size in the CMS | |
| 250 // generation may be larger than that in, say, a contiguous young | |
| 251 // generation. | |
| 252 // Ideally, in the calculation below, we'd compute the dilatation | |
| 253 // factor as: MinChunkSize/(promoting_gen's min object size) | |
| 254 // Since we do not have such a general query interface for the | |
| 255 // promoting generation, we'll instead just use the mimimum | |
| 256 // object size (which today is a header's worth of space); | |
| 257 // note that all arithmetic is in units of HeapWords. | |
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258 assert(MinChunkSize >= CollectedHeap::min_fill_size(), "just checking"); |
| 0 | 259 assert(_dilatation_factor >= 1.0, "from previous assert"); |
| 260 } | |
| 261 | |
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262 |
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263 // The field "_initiating_occupancy" represents the occupancy percentage |
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264 // at which we trigger a new collection cycle. Unless explicitly specified |
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265 // via CMSInitiatingOccupancyFraction (argument "io" below), it |
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266 // is calculated by: |
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267 // |
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268 // Let "f" be MinHeapFreeRatio in |
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269 // |
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270 // _intiating_occupancy = 100-f + |
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271 // f * (CMSTriggerRatio/100) |
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272 // where CMSTriggerRatio is the argument "tr" below. |
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273 // |
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274 // That is, if we assume the heap is at its desired maximum occupancy at the |
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275 // end of a collection, we let CMSTriggerRatio of the (purported) free |
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276 // space be allocated before initiating a new collection cycle. |
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277 // |
| 8035 | 278 void ConcurrentMarkSweepGeneration::init_initiating_occupancy(intx io, uintx tr) { |
| 279 assert(io <= 100 && tr <= 100, "Check the arguments"); | |
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280 if (io >= 0) { |
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281 _initiating_occupancy = (double)io / 100.0; |
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282 } else { |
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283 _initiating_occupancy = ((100 - MinHeapFreeRatio) + |
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284 (double)(tr * MinHeapFreeRatio) / 100.0) |
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285 / 100.0; |
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286 } |
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287 } |
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288 |
| 0 | 289 void ConcurrentMarkSweepGeneration::ref_processor_init() { |
| 290 assert(collector() != NULL, "no collector"); | |
| 291 collector()->ref_processor_init(); | |
| 292 } | |
| 293 | |
| 294 void CMSCollector::ref_processor_init() { | |
| 295 if (_ref_processor == NULL) { | |
| 296 // Allocate and initialize a reference processor | |
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297 _ref_processor = |
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298 new ReferenceProcessor(_span, // span |
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299 (ParallelGCThreads > 1) && ParallelRefProcEnabled, // mt processing |
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300 (int) ParallelGCThreads, // mt processing degree |
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301 _cmsGen->refs_discovery_is_mt(), // mt discovery |
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302 (int) MAX2(ConcGCThreads, ParallelGCThreads), // mt discovery degree |
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303 _cmsGen->refs_discovery_is_atomic(), // discovery is not atomic |
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304 &_is_alive_closure, // closure for liveness info |
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305 false); // next field updates do not need write barrier |
| 0 | 306 // Initialize the _ref_processor field of CMSGen |
| 307 _cmsGen->set_ref_processor(_ref_processor); | |
| 308 | |
| 309 } | |
| 310 } | |
| 311 | |
| 312 CMSAdaptiveSizePolicy* CMSCollector::size_policy() { | |
| 313 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 314 assert(gch->kind() == CollectedHeap::GenCollectedHeap, | |
| 315 "Wrong type of heap"); | |
| 316 CMSAdaptiveSizePolicy* sp = (CMSAdaptiveSizePolicy*) | |
| 317 gch->gen_policy()->size_policy(); | |
| 318 assert(sp->is_gc_cms_adaptive_size_policy(), | |
| 319 "Wrong type of size policy"); | |
| 320 return sp; | |
| 321 } | |
| 322 | |
| 323 CMSGCAdaptivePolicyCounters* CMSCollector::gc_adaptive_policy_counters() { | |
| 324 CMSGCAdaptivePolicyCounters* results = | |
| 325 (CMSGCAdaptivePolicyCounters*) collector_policy()->counters(); | |
| 326 assert( | |
| 327 results->kind() == GCPolicyCounters::CMSGCAdaptivePolicyCountersKind, | |
| 328 "Wrong gc policy counter kind"); | |
| 329 return results; | |
| 330 } | |
| 331 | |
| 332 | |
| 333 void ConcurrentMarkSweepGeneration::initialize_performance_counters() { | |
| 334 | |
| 335 const char* gen_name = "old"; | |
| 336 | |
| 337 // Generation Counters - generation 1, 1 subspace | |
| 338 _gen_counters = new GenerationCounters(gen_name, 1, 1, &_virtual_space); | |
| 339 | |
| 340 _space_counters = new GSpaceCounters(gen_name, 0, | |
| 341 _virtual_space.reserved_size(), | |
| 342 this, _gen_counters); | |
| 343 } | |
| 344 | |
| 345 CMSStats::CMSStats(ConcurrentMarkSweepGeneration* cms_gen, unsigned int alpha): | |
| 346 _cms_gen(cms_gen) | |
| 347 { | |
| 348 assert(alpha <= 100, "bad value"); | |
| 349 _saved_alpha = alpha; | |
| 350 | |
| 351 // Initialize the alphas to the bootstrap value of 100. | |
| 352 _gc0_alpha = _cms_alpha = 100; | |
| 353 | |
| 354 _cms_begin_time.update(); | |
| 355 _cms_end_time.update(); | |
| 356 | |
| 357 _gc0_duration = 0.0; | |
| 358 _gc0_period = 0.0; | |
| 359 _gc0_promoted = 0; | |
| 360 | |
| 361 _cms_duration = 0.0; | |
| 362 _cms_period = 0.0; | |
| 363 _cms_allocated = 0; | |
| 364 | |
| 365 _cms_used_at_gc0_begin = 0; | |
| 366 _cms_used_at_gc0_end = 0; | |
| 367 _allow_duty_cycle_reduction = false; | |
| 368 _valid_bits = 0; | |
| 369 _icms_duty_cycle = CMSIncrementalDutyCycle; | |
| 370 } | |
| 371 | |
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372 double CMSStats::cms_free_adjustment_factor(size_t free) const { |
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373 // TBD: CR 6909490 |
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374 return 1.0; |
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375 } |
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376 |
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377 void CMSStats::adjust_cms_free_adjustment_factor(bool fail, size_t free) { |
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378 } |
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379 |
| 0 | 380 // If promotion failure handling is on use |
| 381 // the padded average size of the promotion for each | |
| 382 // young generation collection. | |
| 383 double CMSStats::time_until_cms_gen_full() const { | |
| 384 size_t cms_free = _cms_gen->cmsSpace()->free(); | |
| 385 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
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386 size_t expected_promotion = MIN2(gch->get_gen(0)->capacity(), |
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387 (size_t) _cms_gen->gc_stats()->avg_promoted()->padded_average()); |
| 0 | 388 if (cms_free > expected_promotion) { |
| 389 // Start a cms collection if there isn't enough space to promote | |
| 390 // for the next minor collection. Use the padded average as | |
| 391 // a safety factor. | |
| 392 cms_free -= expected_promotion; | |
| 393 | |
| 394 // Adjust by the safety factor. | |
| 395 double cms_free_dbl = (double)cms_free; | |
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396 double cms_adjustment = (100.0 - CMSIncrementalSafetyFactor)/100.0; |
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397 // Apply a further correction factor which tries to adjust |
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398 // for recent occurance of concurrent mode failures. |
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399 cms_adjustment = cms_adjustment * cms_free_adjustment_factor(cms_free); |
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400 cms_free_dbl = cms_free_dbl * cms_adjustment; |
| 0 | 401 |
| 402 if (PrintGCDetails && Verbose) { | |
| 403 gclog_or_tty->print_cr("CMSStats::time_until_cms_gen_full: cms_free " | |
| 404 SIZE_FORMAT " expected_promotion " SIZE_FORMAT, | |
| 405 cms_free, expected_promotion); | |
| 406 gclog_or_tty->print_cr(" cms_free_dbl %f cms_consumption_rate %f", | |
| 407 cms_free_dbl, cms_consumption_rate() + 1.0); | |
| 408 } | |
| 409 // Add 1 in case the consumption rate goes to zero. | |
| 410 return cms_free_dbl / (cms_consumption_rate() + 1.0); | |
| 411 } | |
| 412 return 0.0; | |
| 413 } | |
| 414 | |
| 415 // Compare the duration of the cms collection to the | |
| 416 // time remaining before the cms generation is empty. | |
| 417 // Note that the time from the start of the cms collection | |
| 418 // to the start of the cms sweep (less than the total | |
| 419 // duration of the cms collection) can be used. This | |
| 420 // has been tried and some applications experienced | |
| 421 // promotion failures early in execution. This was | |
| 422 // possibly because the averages were not accurate | |
| 423 // enough at the beginning. | |
| 424 double CMSStats::time_until_cms_start() const { | |
| 425 // We add "gc0_period" to the "work" calculation | |
| 426 // below because this query is done (mostly) at the | |
| 427 // end of a scavenge, so we need to conservatively | |
| 428 // account for that much possible delay | |
| 429 // in the query so as to avoid concurrent mode failures | |
| 430 // due to starting the collection just a wee bit too | |
| 431 // late. | |
| 432 double work = cms_duration() + gc0_period(); | |
| 433 double deadline = time_until_cms_gen_full(); | |
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434 // If a concurrent mode failure occurred recently, we want to be |
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435 // more conservative and halve our expected time_until_cms_gen_full() |
| 0 | 436 if (work > deadline) { |
| 437 if (Verbose && PrintGCDetails) { | |
| 438 gclog_or_tty->print( | |
| 439 " CMSCollector: collect because of anticipated promotion " | |
| 440 "before full %3.7f + %3.7f > %3.7f ", cms_duration(), | |
| 441 gc0_period(), time_until_cms_gen_full()); | |
| 442 } | |
| 443 return 0.0; | |
| 444 } | |
| 445 return work - deadline; | |
| 446 } | |
| 447 | |
| 448 // Return a duty cycle based on old_duty_cycle and new_duty_cycle, limiting the | |
| 449 // amount of change to prevent wild oscillation. | |
| 450 unsigned int CMSStats::icms_damped_duty_cycle(unsigned int old_duty_cycle, | |
| 451 unsigned int new_duty_cycle) { | |
| 452 assert(old_duty_cycle <= 100, "bad input value"); | |
| 453 assert(new_duty_cycle <= 100, "bad input value"); | |
| 454 | |
| 455 // Note: use subtraction with caution since it may underflow (values are | |
| 456 // unsigned). Addition is safe since we're in the range 0-100. | |
| 457 unsigned int damped_duty_cycle = new_duty_cycle; | |
| 458 if (new_duty_cycle < old_duty_cycle) { | |
| 459 const unsigned int largest_delta = MAX2(old_duty_cycle / 4, 5U); | |
| 460 if (new_duty_cycle + largest_delta < old_duty_cycle) { | |
| 461 damped_duty_cycle = old_duty_cycle - largest_delta; | |
| 462 } | |
| 463 } else if (new_duty_cycle > old_duty_cycle) { | |
| 464 const unsigned int largest_delta = MAX2(old_duty_cycle / 4, 15U); | |
| 465 if (new_duty_cycle > old_duty_cycle + largest_delta) { | |
| 466 damped_duty_cycle = MIN2(old_duty_cycle + largest_delta, 100U); | |
| 467 } | |
| 468 } | |
| 469 assert(damped_duty_cycle <= 100, "invalid duty cycle computed"); | |
| 470 | |
| 471 if (CMSTraceIncrementalPacing) { | |
| 472 gclog_or_tty->print(" [icms_damped_duty_cycle(%d,%d) = %d] ", | |
| 473 old_duty_cycle, new_duty_cycle, damped_duty_cycle); | |
| 474 } | |
| 475 return damped_duty_cycle; | |
| 476 } | |
| 477 | |
| 478 unsigned int CMSStats::icms_update_duty_cycle_impl() { | |
| 479 assert(CMSIncrementalPacing && valid(), | |
| 480 "should be handled in icms_update_duty_cycle()"); | |
| 481 | |
| 482 double cms_time_so_far = cms_timer().seconds(); | |
| 483 double scaled_duration = cms_duration_per_mb() * _cms_used_at_gc0_end / M; | |
| 484 double scaled_duration_remaining = fabsd(scaled_duration - cms_time_so_far); | |
| 485 | |
| 486 // Avoid division by 0. | |
| 487 double time_until_full = MAX2(time_until_cms_gen_full(), 0.01); | |
| 488 double duty_cycle_dbl = 100.0 * scaled_duration_remaining / time_until_full; | |
| 489 | |
| 490 unsigned int new_duty_cycle = MIN2((unsigned int)duty_cycle_dbl, 100U); | |
| 491 if (new_duty_cycle > _icms_duty_cycle) { | |
| 492 // Avoid very small duty cycles (1 or 2); 0 is allowed. | |
| 493 if (new_duty_cycle > 2) { | |
| 494 _icms_duty_cycle = icms_damped_duty_cycle(_icms_duty_cycle, | |
| 495 new_duty_cycle); | |
| 496 } | |
| 497 } else if (_allow_duty_cycle_reduction) { | |
| 498 // The duty cycle is reduced only once per cms cycle (see record_cms_end()). | |
| 499 new_duty_cycle = icms_damped_duty_cycle(_icms_duty_cycle, new_duty_cycle); | |
| 500 // Respect the minimum duty cycle. | |
| 501 unsigned int min_duty_cycle = (unsigned int)CMSIncrementalDutyCycleMin; | |
| 502 _icms_duty_cycle = MAX2(new_duty_cycle, min_duty_cycle); | |
| 503 } | |
| 504 | |
| 505 if (PrintGCDetails || CMSTraceIncrementalPacing) { | |
| 506 gclog_or_tty->print(" icms_dc=%d ", _icms_duty_cycle); | |
| 507 } | |
| 508 | |
| 509 _allow_duty_cycle_reduction = false; | |
| 510 return _icms_duty_cycle; | |
| 511 } | |
| 512 | |
| 513 #ifndef PRODUCT | |
| 514 void CMSStats::print_on(outputStream *st) const { | |
| 515 st->print(" gc0_alpha=%d,cms_alpha=%d", _gc0_alpha, _cms_alpha); | |
| 516 st->print(",gc0_dur=%g,gc0_per=%g,gc0_promo=" SIZE_FORMAT, | |
| 517 gc0_duration(), gc0_period(), gc0_promoted()); | |
| 518 st->print(",cms_dur=%g,cms_dur_per_mb=%g,cms_per=%g,cms_alloc=" SIZE_FORMAT, | |
| 519 cms_duration(), cms_duration_per_mb(), | |
| 520 cms_period(), cms_allocated()); | |
| 521 st->print(",cms_since_beg=%g,cms_since_end=%g", | |
| 522 cms_time_since_begin(), cms_time_since_end()); | |
| 523 st->print(",cms_used_beg=" SIZE_FORMAT ",cms_used_end=" SIZE_FORMAT, | |
| 524 _cms_used_at_gc0_begin, _cms_used_at_gc0_end); | |
| 525 if (CMSIncrementalMode) { | |
| 526 st->print(",dc=%d", icms_duty_cycle()); | |
| 527 } | |
| 528 | |
| 529 if (valid()) { | |
| 530 st->print(",promo_rate=%g,cms_alloc_rate=%g", | |
| 531 promotion_rate(), cms_allocation_rate()); | |
| 532 st->print(",cms_consumption_rate=%g,time_until_full=%g", | |
| 533 cms_consumption_rate(), time_until_cms_gen_full()); | |
| 534 } | |
| 535 st->print(" "); | |
| 536 } | |
| 537 #endif // #ifndef PRODUCT | |
| 538 | |
| 539 CMSCollector::CollectorState CMSCollector::_collectorState = | |
| 540 CMSCollector::Idling; | |
| 541 bool CMSCollector::_foregroundGCIsActive = false; | |
| 542 bool CMSCollector::_foregroundGCShouldWait = false; | |
| 543 | |
| 544 CMSCollector::CMSCollector(ConcurrentMarkSweepGeneration* cmsGen, | |
| 545 CardTableRS* ct, | |
| 546 ConcurrentMarkSweepPolicy* cp): | |
| 547 _cmsGen(cmsGen), | |
| 548 _ct(ct), | |
| 549 _ref_processor(NULL), // will be set later | |
| 550 _conc_workers(NULL), // may be set later | |
| 551 _abort_preclean(false), | |
| 552 _start_sampling(false), | |
| 553 _between_prologue_and_epilogue(false), | |
| 554 _markBitMap(0, Mutex::leaf + 1, "CMS_markBitMap_lock"), | |
| 555 _modUnionTable((CardTableModRefBS::card_shift - LogHeapWordSize), | |
| 556 -1 /* lock-free */, "No_lock" /* dummy */), | |
| 557 _modUnionClosure(&_modUnionTable), | |
| 558 _modUnionClosurePar(&_modUnionTable), | |
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559 // Adjust my span to cover old (cms) gen |
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560 _span(cmsGen->reserved()), |
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561 // Construct the is_alive_closure with _span & markBitMap |
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562 _is_alive_closure(_span, &_markBitMap), |
| 0 | 563 _restart_addr(NULL), |
| 564 _overflow_list(NULL), | |
| 565 _stats(cmsGen), | |
| 566 _eden_chunk_array(NULL), // may be set in ctor body | |
| 567 _eden_chunk_capacity(0), // -- ditto -- | |
| 568 _eden_chunk_index(0), // -- ditto -- | |
| 569 _survivor_plab_array(NULL), // -- ditto -- | |
| 570 _survivor_chunk_array(NULL), // -- ditto -- | |
| 571 _survivor_chunk_capacity(0), // -- ditto -- | |
| 572 _survivor_chunk_index(0), // -- ditto -- | |
| 573 _ser_pmc_preclean_ovflw(0), | |
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574 _ser_kac_preclean_ovflw(0), |
| 0 | 575 _ser_pmc_remark_ovflw(0), |
| 576 _par_pmc_remark_ovflw(0), | |
| 577 _ser_kac_ovflw(0), | |
| 578 _par_kac_ovflw(0), | |
| 579 #ifndef PRODUCT | |
| 580 _num_par_pushes(0), | |
| 581 #endif | |
| 582 _collection_count_start(0), | |
| 583 _verifying(false), | |
| 584 _icms_start_limit(NULL), | |
| 585 _icms_stop_limit(NULL), | |
| 586 _verification_mark_bm(0, Mutex::leaf + 1, "CMS_verification_mark_bm_lock"), | |
| 587 _completed_initialization(false), | |
| 588 _collector_policy(cp), | |
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589 _should_unload_classes(false), |
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590 _concurrent_cycles_since_last_unload(0), |
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591 _roots_scanning_options(0), |
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592 _inter_sweep_estimate(CMS_SweepWeight, CMS_SweepPadding), |
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593 _intra_sweep_estimate(CMS_SweepWeight, CMS_SweepPadding) |
| 0 | 594 { |
| 595 if (ExplicitGCInvokesConcurrentAndUnloadsClasses) { | |
| 596 ExplicitGCInvokesConcurrent = true; | |
| 597 } | |
| 598 // Now expand the span and allocate the collection support structures | |
| 599 // (MUT, marking bit map etc.) to cover both generations subject to | |
| 600 // collection. | |
| 601 | |
| 602 // For use by dirty card to oop closures. | |
| 603 _cmsGen->cmsSpace()->set_collector(this); | |
| 604 | |
| 605 // Allocate MUT and marking bit map | |
| 606 { | |
| 607 MutexLockerEx x(_markBitMap.lock(), Mutex::_no_safepoint_check_flag); | |
| 608 if (!_markBitMap.allocate(_span)) { | |
| 609 warning("Failed to allocate CMS Bit Map"); | |
| 610 return; | |
| 611 } | |
| 612 assert(_markBitMap.covers(_span), "_markBitMap inconsistency?"); | |
| 613 } | |
| 614 { | |
| 615 _modUnionTable.allocate(_span); | |
| 616 assert(_modUnionTable.covers(_span), "_modUnionTable inconsistency?"); | |
| 617 } | |
| 618 | |
| 1284 | 619 if (!_markStack.allocate(MarkStackSize)) { |
| 0 | 620 warning("Failed to allocate CMS Marking Stack"); |
| 621 return; | |
| 622 } | |
| 623 | |
| 624 // Support for multi-threaded concurrent phases | |
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625 if (CMSConcurrentMTEnabled) { |
| 1284 | 626 if (FLAG_IS_DEFAULT(ConcGCThreads)) { |
| 0 | 627 // just for now |
| 1284 | 628 FLAG_SET_DEFAULT(ConcGCThreads, (ParallelGCThreads + 3)/4); |
| 629 } | |
| 630 if (ConcGCThreads > 1) { | |
| 0 | 631 _conc_workers = new YieldingFlexibleWorkGang("Parallel CMS Threads", |
| 1284 | 632 ConcGCThreads, true); |
| 0 | 633 if (_conc_workers == NULL) { |
| 634 warning("GC/CMS: _conc_workers allocation failure: " | |
| 635 "forcing -CMSConcurrentMTEnabled"); | |
| 636 CMSConcurrentMTEnabled = false; | |
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637 } else { |
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638 _conc_workers->initialize_workers(); |
| 0 | 639 } |
| 640 } else { | |
| 641 CMSConcurrentMTEnabled = false; | |
| 642 } | |
| 643 } | |
| 644 if (!CMSConcurrentMTEnabled) { | |
| 1284 | 645 ConcGCThreads = 0; |
| 0 | 646 } else { |
| 647 // Turn off CMSCleanOnEnter optimization temporarily for | |
| 648 // the MT case where it's not fixed yet; see 6178663. | |
| 649 CMSCleanOnEnter = false; | |
| 650 } | |
| 1284 | 651 assert((_conc_workers != NULL) == (ConcGCThreads > 1), |
| 0 | 652 "Inconsistency"); |
| 653 | |
| 654 // Parallel task queues; these are shared for the | |
| 655 // concurrent and stop-world phases of CMS, but | |
| 656 // are not shared with parallel scavenge (ParNew). | |
| 657 { | |
| 658 uint i; | |
| 1284 | 659 uint num_queues = (uint) MAX2(ParallelGCThreads, ConcGCThreads); |
| 0 | 660 |
| 661 if ((CMSParallelRemarkEnabled || CMSConcurrentMTEnabled | |
| 662 || ParallelRefProcEnabled) | |
| 663 && num_queues > 0) { | |
| 664 _task_queues = new OopTaskQueueSet(num_queues); | |
| 665 if (_task_queues == NULL) { | |
| 666 warning("task_queues allocation failure."); | |
| 667 return; | |
| 668 } | |
| 6197 | 669 _hash_seed = NEW_C_HEAP_ARRAY(int, num_queues, mtGC); |
| 0 | 670 if (_hash_seed == NULL) { |
| 671 warning("_hash_seed array allocation failure"); | |
| 672 return; | |
| 673 } | |
| 674 | |
| 1665 | 675 typedef Padded<OopTaskQueue> PaddedOopTaskQueue; |
| 0 | 676 for (i = 0; i < num_queues; i++) { |
| 1665 | 677 PaddedOopTaskQueue *q = new PaddedOopTaskQueue(); |
| 678 if (q == NULL) { | |
| 0 | 679 warning("work_queue allocation failure."); |
| 680 return; | |
| 681 } | |
| 1665 | 682 _task_queues->register_queue(i, q); |
| 0 | 683 } |
| 684 for (i = 0; i < num_queues; i++) { | |
| 685 _task_queues->queue(i)->initialize(); | |
| 686 _hash_seed[i] = 17; // copied from ParNew | |
| 687 } | |
| 688 } | |
| 689 } | |
| 690 | |
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691 _cmsGen ->init_initiating_occupancy(CMSInitiatingOccupancyFraction, CMSTriggerRatio); |
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692 |
| 0 | 693 // Clip CMSBootstrapOccupancy between 0 and 100. |
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694 _bootstrap_occupancy = ((double)MIN2((uintx)100, MAX2((uintx)0, CMSBootstrapOccupancy))) |
| 0 | 695 /(double)100; |
| 696 | |
| 697 _full_gcs_since_conc_gc = 0; | |
| 698 | |
| 699 // Now tell CMS generations the identity of their collector | |
| 700 ConcurrentMarkSweepGeneration::set_collector(this); | |
| 701 | |
| 702 // Create & start a CMS thread for this CMS collector | |
| 703 _cmsThread = ConcurrentMarkSweepThread::start(this); | |
| 704 assert(cmsThread() != NULL, "CMS Thread should have been created"); | |
| 705 assert(cmsThread()->collector() == this, | |
| 706 "CMS Thread should refer to this gen"); | |
| 707 assert(CGC_lock != NULL, "Where's the CGC_lock?"); | |
| 708 | |
| 709 // Support for parallelizing young gen rescan | |
| 710 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 711 _young_gen = gch->prev_gen(_cmsGen); | |
| 712 if (gch->supports_inline_contig_alloc()) { | |
| 713 _top_addr = gch->top_addr(); | |
| 714 _end_addr = gch->end_addr(); | |
| 715 assert(_young_gen != NULL, "no _young_gen"); | |
| 716 _eden_chunk_index = 0; | |
| 717 _eden_chunk_capacity = (_young_gen->max_capacity()+CMSSamplingGrain)/CMSSamplingGrain; | |
| 6197 | 718 _eden_chunk_array = NEW_C_HEAP_ARRAY(HeapWord*, _eden_chunk_capacity, mtGC); |
| 0 | 719 if (_eden_chunk_array == NULL) { |
| 720 _eden_chunk_capacity = 0; | |
| 721 warning("GC/CMS: _eden_chunk_array allocation failure"); | |
| 722 } | |
| 723 } | |
| 724 assert(_eden_chunk_array != NULL || _eden_chunk_capacity == 0, "Error"); | |
| 725 | |
| 726 // Support for parallelizing survivor space rescan | |
| 727 if (CMSParallelRemarkEnabled && CMSParallelSurvivorRemarkEnabled) { | |
|
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728 const size_t max_plab_samples = |
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729 ((DefNewGeneration*)_young_gen)->max_survivor_size()/MinTLABSize; |
|
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730 |
| 6197 | 731 _survivor_plab_array = NEW_C_HEAP_ARRAY(ChunkArray, ParallelGCThreads, mtGC); |
| 732 _survivor_chunk_array = NEW_C_HEAP_ARRAY(HeapWord*, 2*max_plab_samples, mtGC); | |
| 733 _cursor = NEW_C_HEAP_ARRAY(size_t, ParallelGCThreads, mtGC); | |
| 0 | 734 if (_survivor_plab_array == NULL || _survivor_chunk_array == NULL |
| 735 || _cursor == NULL) { | |
| 736 warning("Failed to allocate survivor plab/chunk array"); | |
| 737 if (_survivor_plab_array != NULL) { | |
| 6197 | 738 FREE_C_HEAP_ARRAY(ChunkArray, _survivor_plab_array, mtGC); |
| 0 | 739 _survivor_plab_array = NULL; |
| 740 } | |
| 741 if (_survivor_chunk_array != NULL) { | |
| 6197 | 742 FREE_C_HEAP_ARRAY(HeapWord*, _survivor_chunk_array, mtGC); |
| 0 | 743 _survivor_chunk_array = NULL; |
| 744 } | |
| 745 if (_cursor != NULL) { | |
| 6197 | 746 FREE_C_HEAP_ARRAY(size_t, _cursor, mtGC); |
| 0 | 747 _cursor = NULL; |
| 748 } | |
| 749 } else { | |
| 750 _survivor_chunk_capacity = 2*max_plab_samples; | |
| 751 for (uint i = 0; i < ParallelGCThreads; i++) { | |
| 6197 | 752 HeapWord** vec = NEW_C_HEAP_ARRAY(HeapWord*, max_plab_samples, mtGC); |
| 0 | 753 if (vec == NULL) { |
| 754 warning("Failed to allocate survivor plab array"); | |
| 755 for (int j = i; j > 0; j--) { | |
| 6197 | 756 FREE_C_HEAP_ARRAY(HeapWord*, _survivor_plab_array[j-1].array(), mtGC); |
| 0 | 757 } |
| 6197 | 758 FREE_C_HEAP_ARRAY(ChunkArray, _survivor_plab_array, mtGC); |
| 759 FREE_C_HEAP_ARRAY(HeapWord*, _survivor_chunk_array, mtGC); | |
| 0 | 760 _survivor_plab_array = NULL; |
| 761 _survivor_chunk_array = NULL; | |
| 762 _survivor_chunk_capacity = 0; | |
| 763 break; | |
| 764 } else { | |
| 765 ChunkArray* cur = | |
| 766 ::new (&_survivor_plab_array[i]) ChunkArray(vec, | |
| 767 max_plab_samples); | |
| 768 assert(cur->end() == 0, "Should be 0"); | |
| 769 assert(cur->array() == vec, "Should be vec"); | |
| 770 assert(cur->capacity() == max_plab_samples, "Error"); | |
| 771 } | |
| 772 } | |
| 773 } | |
| 774 } | |
| 775 assert( ( _survivor_plab_array != NULL | |
| 776 && _survivor_chunk_array != NULL) | |
| 777 || ( _survivor_chunk_capacity == 0 | |
| 778 && _survivor_chunk_index == 0), | |
| 779 "Error"); | |
| 780 | |
| 781 // Choose what strong roots should be scanned depending on verification options | |
| 782 if (!CMSClassUnloadingEnabled) { | |
| 783 // If class unloading is disabled we want to include all classes into the root set. | |
| 784 add_root_scanning_option(SharedHeap::SO_AllClasses); | |
| 785 } else { | |
| 786 add_root_scanning_option(SharedHeap::SO_SystemClasses); | |
| 787 } | |
| 788 | |
| 789 NOT_PRODUCT(_overflow_counter = CMSMarkStackOverflowInterval;) | |
| 790 _gc_counters = new CollectorCounters("CMS", 1); | |
| 791 _completed_initialization = true; | |
|
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792 _inter_sweep_timer.start(); // start of time |
| 0 | 793 } |
| 794 | |
| 795 const char* ConcurrentMarkSweepGeneration::name() const { | |
| 796 return "concurrent mark-sweep generation"; | |
| 797 } | |
| 798 void ConcurrentMarkSweepGeneration::update_counters() { | |
| 799 if (UsePerfData) { | |
| 800 _space_counters->update_all(); | |
| 801 _gen_counters->update_all(); | |
| 802 } | |
| 803 } | |
| 804 | |
| 805 // this is an optimized version of update_counters(). it takes the | |
| 806 // used value as a parameter rather than computing it. | |
| 807 // | |
| 808 void ConcurrentMarkSweepGeneration::update_counters(size_t used) { | |
| 809 if (UsePerfData) { | |
| 810 _space_counters->update_used(used); | |
| 811 _space_counters->update_capacity(); | |
| 812 _gen_counters->update_all(); | |
| 813 } | |
| 814 } | |
| 815 | |
| 816 void ConcurrentMarkSweepGeneration::print() const { | |
| 817 Generation::print(); | |
| 818 cmsSpace()->print(); | |
| 819 } | |
| 820 | |
| 821 #ifndef PRODUCT | |
| 822 void ConcurrentMarkSweepGeneration::print_statistics() { | |
| 823 cmsSpace()->printFLCensus(0); | |
| 824 } | |
| 825 #endif | |
| 826 | |
| 827 void ConcurrentMarkSweepGeneration::printOccupancy(const char *s) { | |
| 828 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 829 if (PrintGCDetails) { | |
| 830 if (Verbose) { | |
|
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831 gclog_or_tty->print("[%d %s-%s: "SIZE_FORMAT"("SIZE_FORMAT")]", |
| 0 | 832 level(), short_name(), s, used(), capacity()); |
| 833 } else { | |
|
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834 gclog_or_tty->print("[%d %s-%s: "SIZE_FORMAT"K("SIZE_FORMAT"K)]", |
| 0 | 835 level(), short_name(), s, used() / K, capacity() / K); |
| 836 } | |
| 837 } | |
| 838 if (Verbose) { | |
| 839 gclog_or_tty->print(" "SIZE_FORMAT"("SIZE_FORMAT")", | |
| 840 gch->used(), gch->capacity()); | |
| 841 } else { | |
| 842 gclog_or_tty->print(" "SIZE_FORMAT"K("SIZE_FORMAT"K)", | |
| 843 gch->used() / K, gch->capacity() / K); | |
| 844 } | |
| 845 } | |
| 846 | |
| 847 size_t | |
| 848 ConcurrentMarkSweepGeneration::contiguous_available() const { | |
| 849 // dld proposes an improvement in precision here. If the committed | |
| 850 // part of the space ends in a free block we should add that to | |
| 851 // uncommitted size in the calculation below. Will make this | |
| 852 // change later, staying with the approximation below for the | |
| 853 // time being. -- ysr. | |
| 854 return MAX2(_virtual_space.uncommitted_size(), unsafe_max_alloc_nogc()); | |
| 855 } | |
| 856 | |
| 857 size_t | |
| 858 ConcurrentMarkSweepGeneration::unsafe_max_alloc_nogc() const { | |
| 859 return _cmsSpace->max_alloc_in_words() * HeapWordSize; | |
| 860 } | |
| 861 | |
| 862 size_t ConcurrentMarkSweepGeneration::max_available() const { | |
| 863 return free() + _virtual_space.uncommitted_size(); | |
| 864 } | |
| 865 | |
|
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866 bool ConcurrentMarkSweepGeneration::promotion_attempt_is_safe(size_t max_promotion_in_bytes) const { |
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867 size_t available = max_available(); |
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868 size_t av_promo = (size_t)gc_stats()->avg_promoted()->padded_average(); |
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869 bool res = (available >= av_promo) || (available >= max_promotion_in_bytes); |
|
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870 if (Verbose && PrintGCDetails) { |
|
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871 gclog_or_tty->print_cr( |
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872 "CMS: promo attempt is%s safe: available("SIZE_FORMAT") %s av_promo("SIZE_FORMAT")," |
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873 "max_promo("SIZE_FORMAT")", |
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874 res? "":" not", available, res? ">=":"<", |
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875 av_promo, max_promotion_in_bytes); |
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876 } |
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877 return res; |
| 0 | 878 } |
| 879 | |
|
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880 // At a promotion failure dump information on block layout in heap |
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881 // (cms old generation). |
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882 void ConcurrentMarkSweepGeneration::promotion_failure_occurred() { |
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883 if (CMSDumpAtPromotionFailure) { |
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884 cmsSpace()->dump_at_safepoint_with_locks(collector(), gclog_or_tty); |
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885 } |
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886 } |
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887 |
| 0 | 888 CompactibleSpace* |
| 889 ConcurrentMarkSweepGeneration::first_compaction_space() const { | |
| 890 return _cmsSpace; | |
| 891 } | |
| 892 | |
| 893 void ConcurrentMarkSweepGeneration::reset_after_compaction() { | |
| 894 // Clear the promotion information. These pointers can be adjusted | |
| 895 // along with all the other pointers into the heap but | |
| 896 // compaction is expected to be a rare event with | |
| 897 // a heap using cms so don't do it without seeing the need. | |
|
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898 if (CollectedHeap::use_parallel_gc_threads()) { |
| 0 | 899 for (uint i = 0; i < ParallelGCThreads; i++) { |
| 900 _par_gc_thread_states[i]->promo.reset(); | |
| 901 } | |
| 902 } | |
| 903 } | |
| 904 | |
| 905 void ConcurrentMarkSweepGeneration::space_iterate(SpaceClosure* blk, bool usedOnly) { | |
| 906 blk->do_space(_cmsSpace); | |
| 907 } | |
| 908 | |
| 909 void ConcurrentMarkSweepGeneration::compute_new_size() { | |
| 910 assert_locked_or_safepoint(Heap_lock); | |
| 911 | |
| 912 // If incremental collection failed, we just want to expand | |
| 913 // to the limit. | |
| 914 if (incremental_collection_failed()) { | |
| 915 clear_incremental_collection_failed(); | |
| 916 grow_to_reserved(); | |
| 917 return; | |
| 918 } | |
| 919 | |
|
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920 // Compute some numbers about the state of the heap. |
|
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921 const size_t used_after_gc = used(); |
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922 const size_t capacity_after_gc = capacity(); |
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923 |
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924 CardGeneration::compute_new_size(); |
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925 |
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926 // Reset again after a possible resizing |
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927 cmsSpace()->reset_after_compaction(); |
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928 |
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929 assert(used() == used_after_gc && used_after_gc <= capacity(), |
|
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930 err_msg("used: " SIZE_FORMAT " used_after_gc: " SIZE_FORMAT |
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931 " capacity: " SIZE_FORMAT, used(), used_after_gc, capacity())); |
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932 } |
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933 |
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934 void ConcurrentMarkSweepGeneration::compute_new_size_free_list() { |
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935 assert_locked_or_safepoint(Heap_lock); |
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936 |
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937 // If incremental collection failed, we just want to expand |
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938 // to the limit. |
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939 if (incremental_collection_failed()) { |
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940 clear_incremental_collection_failed(); |
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941 grow_to_reserved(); |
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942 return; |
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943 } |
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944 |
| 0 | 945 double free_percentage = ((double) free()) / capacity(); |
| 946 double desired_free_percentage = (double) MinHeapFreeRatio / 100; | |
| 947 double maximum_free_percentage = (double) MaxHeapFreeRatio / 100; | |
| 948 | |
| 949 // compute expansion delta needed for reaching desired free percentage | |
| 950 if (free_percentage < desired_free_percentage) { | |
| 951 size_t desired_capacity = (size_t)(used() / ((double) 1 - desired_free_percentage)); | |
| 952 assert(desired_capacity >= capacity(), "invalid expansion size"); | |
|
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953 size_t expand_bytes = MAX2(desired_capacity - capacity(), MinHeapDeltaBytes); |
| 0 | 954 if (PrintGCDetails && Verbose) { |
| 955 size_t desired_capacity = (size_t)(used() / ((double) 1 - desired_free_percentage)); | |
| 956 gclog_or_tty->print_cr("\nFrom compute_new_size: "); | |
| 957 gclog_or_tty->print_cr(" Free fraction %f", free_percentage); | |
| 958 gclog_or_tty->print_cr(" Desired free fraction %f", | |
| 959 desired_free_percentage); | |
| 960 gclog_or_tty->print_cr(" Maximum free fraction %f", | |
| 961 maximum_free_percentage); | |
| 962 gclog_or_tty->print_cr(" Capactiy "SIZE_FORMAT, capacity()/1000); | |
| 963 gclog_or_tty->print_cr(" Desired capacity "SIZE_FORMAT, | |
| 964 desired_capacity/1000); | |
| 965 int prev_level = level() - 1; | |
| 966 if (prev_level >= 0) { | |
| 967 size_t prev_size = 0; | |
| 968 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 969 Generation* prev_gen = gch->_gens[prev_level]; | |
| 970 prev_size = prev_gen->capacity(); | |
| 971 gclog_or_tty->print_cr(" Younger gen size "SIZE_FORMAT, | |
| 972 prev_size/1000); | |
| 973 } | |
| 974 gclog_or_tty->print_cr(" unsafe_max_alloc_nogc "SIZE_FORMAT, | |
| 975 unsafe_max_alloc_nogc()/1000); | |
| 976 gclog_or_tty->print_cr(" contiguous available "SIZE_FORMAT, | |
| 977 contiguous_available()/1000); | |
| 978 gclog_or_tty->print_cr(" Expand by "SIZE_FORMAT" (bytes)", | |
| 979 expand_bytes); | |
| 980 } | |
| 981 // safe if expansion fails | |
| 982 expand(expand_bytes, 0, CMSExpansionCause::_satisfy_free_ratio); | |
| 983 if (PrintGCDetails && Verbose) { | |
| 984 gclog_or_tty->print_cr(" Expanded free fraction %f", | |
| 985 ((double) free()) / capacity()); | |
| 986 } | |
|
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987 } else { |
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988 size_t desired_capacity = (size_t)(used() / ((double) 1 - desired_free_percentage)); |
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989 assert(desired_capacity <= capacity(), "invalid expansion size"); |
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990 size_t shrink_bytes = capacity() - desired_capacity; |
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991 // Don't shrink unless the delta is greater than the minimum shrink we want |
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992 if (shrink_bytes >= MinHeapDeltaBytes) { |
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993 shrink_free_list_by(shrink_bytes); |
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994 } |
| 0 | 995 } |
| 996 } | |
| 997 | |
| 998 Mutex* ConcurrentMarkSweepGeneration::freelistLock() const { | |
| 999 return cmsSpace()->freelistLock(); | |
| 1000 } | |
| 1001 | |
| 1002 HeapWord* ConcurrentMarkSweepGeneration::allocate(size_t size, | |
| 1003 bool tlab) { | |
| 1004 CMSSynchronousYieldRequest yr; | |
| 1005 MutexLockerEx x(freelistLock(), | |
| 1006 Mutex::_no_safepoint_check_flag); | |
| 1007 return have_lock_and_allocate(size, tlab); | |
| 1008 } | |
| 1009 | |
| 1010 HeapWord* ConcurrentMarkSweepGeneration::have_lock_and_allocate(size_t size, | |
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1011 bool tlab /* ignored */) { |
| 0 | 1012 assert_lock_strong(freelistLock()); |
| 1013 size_t adjustedSize = CompactibleFreeListSpace::adjustObjectSize(size); | |
| 1014 HeapWord* res = cmsSpace()->allocate(adjustedSize); | |
| 1015 // Allocate the object live (grey) if the background collector has | |
| 1016 // started marking. This is necessary because the marker may | |
| 1017 // have passed this address and consequently this object will | |
| 1018 // not otherwise be greyed and would be incorrectly swept up. | |
| 1019 // Note that if this object contains references, the writing | |
| 1020 // of those references will dirty the card containing this object | |
| 1021 // allowing the object to be blackened (and its references scanned) | |
| 1022 // either during a preclean phase or at the final checkpoint. | |
| 1023 if (res != NULL) { | |
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1024 // We may block here with an uninitialized object with |
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1025 // its mark-bit or P-bits not yet set. Such objects need |
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1026 // to be safely navigable by block_start(). |
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1027 assert(oop(res)->klass_or_null() == NULL, "Object should be uninitialized here."); |
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1028 assert(!((FreeChunk*)res)->is_free(), "Error, block will look free but show wrong size"); |
| 0 | 1029 collector()->direct_allocated(res, adjustedSize); |
| 1030 _direct_allocated_words += adjustedSize; | |
| 1031 // allocation counters | |
| 1032 NOT_PRODUCT( | |
| 1033 _numObjectsAllocated++; | |
| 1034 _numWordsAllocated += (int)adjustedSize; | |
| 1035 ) | |
| 1036 } | |
| 1037 return res; | |
| 1038 } | |
| 1039 | |
| 1040 // In the case of direct allocation by mutators in a generation that | |
| 1041 // is being concurrently collected, the object must be allocated | |
| 1042 // live (grey) if the background collector has started marking. | |
| 1043 // This is necessary because the marker may | |
| 1044 // have passed this address and consequently this object will | |
| 1045 // not otherwise be greyed and would be incorrectly swept up. | |
| 1046 // Note that if this object contains references, the writing | |
| 1047 // of those references will dirty the card containing this object | |
| 1048 // allowing the object to be blackened (and its references scanned) | |
| 1049 // either during a preclean phase or at the final checkpoint. | |
| 1050 void CMSCollector::direct_allocated(HeapWord* start, size_t size) { | |
| 1051 assert(_markBitMap.covers(start, size), "Out of bounds"); | |
| 1052 if (_collectorState >= Marking) { | |
| 1053 MutexLockerEx y(_markBitMap.lock(), | |
| 1054 Mutex::_no_safepoint_check_flag); | |
| 1055 // [see comments preceding SweepClosure::do_blk() below for details] | |
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1056 // |
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1057 // Can the P-bits be deleted now? JJJ |
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1058 // |
| 0 | 1059 // 1. need to mark the object as live so it isn't collected |
| 1060 // 2. need to mark the 2nd bit to indicate the object may be uninitialized | |
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1061 // 3. need to mark the end of the object so marking, precleaning or sweeping |
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1062 // can skip over uninitialized or unparsable objects. An allocated |
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1063 // object is considered uninitialized for our purposes as long as |
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1064 // its klass word is NULL. All old gen objects are parsable |
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1065 // as soon as they are initialized.) |
| 0 | 1066 _markBitMap.mark(start); // object is live |
| 1067 _markBitMap.mark(start + 1); // object is potentially uninitialized? | |
| 1068 _markBitMap.mark(start + size - 1); | |
| 1069 // mark end of object | |
| 1070 } | |
| 1071 // check that oop looks uninitialized | |
| 187 | 1072 assert(oop(start)->klass_or_null() == NULL, "_klass should be NULL"); |
| 0 | 1073 } |
| 1074 | |
| 1075 void CMSCollector::promoted(bool par, HeapWord* start, | |
| 1076 bool is_obj_array, size_t obj_size) { | |
| 1077 assert(_markBitMap.covers(start), "Out of bounds"); | |
| 1078 // See comment in direct_allocated() about when objects should | |
| 1079 // be allocated live. | |
| 1080 if (_collectorState >= Marking) { | |
| 1081 // we already hold the marking bit map lock, taken in | |
| 1082 // the prologue | |
| 1083 if (par) { | |
| 1084 _markBitMap.par_mark(start); | |
| 1085 } else { | |
| 1086 _markBitMap.mark(start); | |
| 1087 } | |
| 1088 // We don't need to mark the object as uninitialized (as | |
| 1089 // in direct_allocated above) because this is being done with the | |
| 1090 // world stopped and the object will be initialized by the | |
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1091 // time the marking, precleaning or sweeping get to look at it. |
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1092 // But see the code for copying objects into the CMS generation, |
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1093 // where we need to ensure that concurrent readers of the |
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1094 // block offset table are able to safely navigate a block that |
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1095 // is in flux from being free to being allocated (and in |
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1096 // transition while being copied into) and subsequently |
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1097 // becoming a bona-fide object when the copy/promotion is complete. |
| 0 | 1098 assert(SafepointSynchronize::is_at_safepoint(), |
| 1099 "expect promotion only at safepoints"); | |
| 1100 | |
| 1101 if (_collectorState < Sweeping) { | |
| 1102 // Mark the appropriate cards in the modUnionTable, so that | |
| 1103 // this object gets scanned before the sweep. If this is | |
| 1104 // not done, CMS generation references in the object might | |
| 1105 // not get marked. | |
| 1106 // For the case of arrays, which are otherwise precisely | |
| 1107 // marked, we need to dirty the entire array, not just its head. | |
| 1108 if (is_obj_array) { | |
| 1109 // The [par_]mark_range() method expects mr.end() below to | |
| 1110 // be aligned to the granularity of a bit's representation | |
| 1111 // in the heap. In the case of the MUT below, that's a | |
| 1112 // card size. | |
| 1113 MemRegion mr(start, | |
| 1114 (HeapWord*)round_to((intptr_t)(start + obj_size), | |
| 1115 CardTableModRefBS::card_size /* bytes */)); | |
| 1116 if (par) { | |
| 1117 _modUnionTable.par_mark_range(mr); | |
| 1118 } else { | |
| 1119 _modUnionTable.mark_range(mr); | |
| 1120 } | |
| 1121 } else { // not an obj array; we can just mark the head | |
| 1122 if (par) { | |
| 1123 _modUnionTable.par_mark(start); | |
| 1124 } else { | |
| 1125 _modUnionTable.mark(start); | |
| 1126 } | |
| 1127 } | |
| 1128 } | |
| 1129 } | |
| 1130 } | |
| 1131 | |
| 1132 static inline size_t percent_of_space(Space* space, HeapWord* addr) | |
| 1133 { | |
| 1134 size_t delta = pointer_delta(addr, space->bottom()); | |
| 1135 return (size_t)(delta * 100.0 / (space->capacity() / HeapWordSize)); | |
| 1136 } | |
| 1137 | |
| 1138 void CMSCollector::icms_update_allocation_limits() | |
| 1139 { | |
| 1140 Generation* gen0 = GenCollectedHeap::heap()->get_gen(0); | |
| 1141 EdenSpace* eden = gen0->as_DefNewGeneration()->eden(); | |
| 1142 | |
| 1143 const unsigned int duty_cycle = stats().icms_update_duty_cycle(); | |
| 1144 if (CMSTraceIncrementalPacing) { | |
| 1145 stats().print(); | |
| 1146 } | |
| 1147 | |
| 1148 assert(duty_cycle <= 100, "invalid duty cycle"); | |
| 1149 if (duty_cycle != 0) { | |
| 1150 // The duty_cycle is a percentage between 0 and 100; convert to words and | |
| 1151 // then compute the offset from the endpoints of the space. | |
| 1152 size_t free_words = eden->free() / HeapWordSize; | |
| 1153 double free_words_dbl = (double)free_words; | |
| 1154 size_t duty_cycle_words = (size_t)(free_words_dbl * duty_cycle / 100.0); | |
| 1155 size_t offset_words = (free_words - duty_cycle_words) / 2; | |
| 1156 | |
| 1157 _icms_start_limit = eden->top() + offset_words; | |
| 1158 _icms_stop_limit = eden->end() - offset_words; | |
| 1159 | |
| 1160 // The limits may be adjusted (shifted to the right) by | |
| 1161 // CMSIncrementalOffset, to allow the application more mutator time after a | |
| 1162 // young gen gc (when all mutators were stopped) and before CMS starts and | |
| 1163 // takes away one or more cpus. | |
| 1164 if (CMSIncrementalOffset != 0) { | |
| 1165 double adjustment_dbl = free_words_dbl * CMSIncrementalOffset / 100.0; | |
| 1166 size_t adjustment = (size_t)adjustment_dbl; | |
| 1167 HeapWord* tmp_stop = _icms_stop_limit + adjustment; | |
| 1168 if (tmp_stop > _icms_stop_limit && tmp_stop < eden->end()) { | |
| 1169 _icms_start_limit += adjustment; | |
| 1170 _icms_stop_limit = tmp_stop; | |
| 1171 } | |
| 1172 } | |
| 1173 } | |
| 1174 if (duty_cycle == 0 || (_icms_start_limit == _icms_stop_limit)) { | |
| 1175 _icms_start_limit = _icms_stop_limit = eden->end(); | |
| 1176 } | |
| 1177 | |
| 1178 // Install the new start limit. | |
| 1179 eden->set_soft_end(_icms_start_limit); | |
| 1180 | |
| 1181 if (CMSTraceIncrementalMode) { | |
| 1182 gclog_or_tty->print(" icms alloc limits: " | |
| 1183 PTR_FORMAT "," PTR_FORMAT | |
| 1184 " (" SIZE_FORMAT "%%," SIZE_FORMAT "%%) ", | |
| 1185 _icms_start_limit, _icms_stop_limit, | |
| 1186 percent_of_space(eden, _icms_start_limit), | |
| 1187 percent_of_space(eden, _icms_stop_limit)); | |
| 1188 if (Verbose) { | |
| 1189 gclog_or_tty->print("eden: "); | |
| 1190 eden->print_on(gclog_or_tty); | |
| 1191 } | |
| 1192 } | |
| 1193 } | |
| 1194 | |
| 1195 // Any changes here should try to maintain the invariant | |
| 1196 // that if this method is called with _icms_start_limit | |
| 1197 // and _icms_stop_limit both NULL, then it should return NULL | |
| 1198 // and not notify the icms thread. | |
| 1199 HeapWord* | |
| 1200 CMSCollector::allocation_limit_reached(Space* space, HeapWord* top, | |
| 1201 size_t word_size) | |
| 1202 { | |
| 1203 // A start_limit equal to end() means the duty cycle is 0, so treat that as a | |
| 1204 // nop. | |
| 1205 if (CMSIncrementalMode && _icms_start_limit != space->end()) { | |
| 1206 if (top <= _icms_start_limit) { | |
| 1207 if (CMSTraceIncrementalMode) { | |
| 1208 space->print_on(gclog_or_tty); | |
| 1209 gclog_or_tty->stamp(); | |
| 1210 gclog_or_tty->print_cr(" start limit top=" PTR_FORMAT | |
| 1211 ", new limit=" PTR_FORMAT | |
| 1212 " (" SIZE_FORMAT "%%)", | |
| 1213 top, _icms_stop_limit, | |
| 1214 percent_of_space(space, _icms_stop_limit)); | |
| 1215 } | |
| 1216 ConcurrentMarkSweepThread::start_icms(); | |
| 1217 assert(top < _icms_stop_limit, "Tautology"); | |
| 1218 if (word_size < pointer_delta(_icms_stop_limit, top)) { | |
| 1219 return _icms_stop_limit; | |
| 1220 } | |
| 1221 | |
| 1222 // The allocation will cross both the _start and _stop limits, so do the | |
| 1223 // stop notification also and return end(). | |
| 1224 if (CMSTraceIncrementalMode) { | |
| 1225 space->print_on(gclog_or_tty); | |
| 1226 gclog_or_tty->stamp(); | |
| 1227 gclog_or_tty->print_cr(" +stop limit top=" PTR_FORMAT | |
| 1228 ", new limit=" PTR_FORMAT | |
| 1229 " (" SIZE_FORMAT "%%)", | |
| 1230 top, space->end(), | |
| 1231 percent_of_space(space, space->end())); | |
| 1232 } | |
| 1233 ConcurrentMarkSweepThread::stop_icms(); | |
| 1234 return space->end(); | |
| 1235 } | |
| 1236 | |
| 1237 if (top <= _icms_stop_limit) { | |
| 1238 if (CMSTraceIncrementalMode) { | |
| 1239 space->print_on(gclog_or_tty); | |
| 1240 gclog_or_tty->stamp(); | |
| 1241 gclog_or_tty->print_cr(" stop limit top=" PTR_FORMAT | |
| 1242 ", new limit=" PTR_FORMAT | |
| 1243 " (" SIZE_FORMAT "%%)", | |
| 1244 top, space->end(), | |
| 1245 percent_of_space(space, space->end())); | |
| 1246 } | |
| 1247 ConcurrentMarkSweepThread::stop_icms(); | |
| 1248 return space->end(); | |
| 1249 } | |
| 1250 | |
| 1251 if (CMSTraceIncrementalMode) { | |
| 1252 space->print_on(gclog_or_tty); | |
| 1253 gclog_or_tty->stamp(); | |
| 1254 gclog_or_tty->print_cr(" end limit top=" PTR_FORMAT | |
| 1255 ", new limit=" PTR_FORMAT, | |
| 1256 top, NULL); | |
| 1257 } | |
| 1258 } | |
| 1259 | |
| 1260 return NULL; | |
| 1261 } | |
| 1262 | |
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1263 oop ConcurrentMarkSweepGeneration::promote(oop obj, size_t obj_size) { |
| 0 | 1264 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in"); |
| 1265 // allocate, copy and if necessary update promoinfo -- | |
| 1266 // delegate to underlying space. | |
| 1267 assert_lock_strong(freelistLock()); | |
| 1268 | |
| 1269 #ifndef PRODUCT | |
| 1270 if (Universe::heap()->promotion_should_fail()) { | |
| 1271 return NULL; | |
| 1272 } | |
| 1273 #endif // #ifndef PRODUCT | |
| 1274 | |
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1275 oop res = _cmsSpace->promote(obj, obj_size); |
| 0 | 1276 if (res == NULL) { |
| 1277 // expand and retry | |
| 1278 size_t s = _cmsSpace->expansionSpaceRequired(obj_size); // HeapWords | |
| 1279 expand(s*HeapWordSize, MinHeapDeltaBytes, | |
| 1280 CMSExpansionCause::_satisfy_promotion); | |
| 1281 // Since there's currently no next generation, we don't try to promote | |
| 1282 // into a more senior generation. | |
| 1283 assert(next_gen() == NULL, "assumption, based upon which no attempt " | |
| 1284 "is made to pass on a possibly failing " | |
| 1285 "promotion to next generation"); | |
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1286 res = _cmsSpace->promote(obj, obj_size); |
| 0 | 1287 } |
| 1288 if (res != NULL) { | |
| 1289 // See comment in allocate() about when objects should | |
| 1290 // be allocated live. | |
| 1291 assert(obj->is_oop(), "Will dereference klass pointer below"); | |
| 1292 collector()->promoted(false, // Not parallel | |
| 1293 (HeapWord*)res, obj->is_objArray(), obj_size); | |
| 1294 // promotion counters | |
| 1295 NOT_PRODUCT( | |
| 1296 _numObjectsPromoted++; | |
| 1297 _numWordsPromoted += | |
| 1298 (int)(CompactibleFreeListSpace::adjustObjectSize(obj->size())); | |
| 1299 ) | |
| 1300 } | |
| 1301 return res; | |
| 1302 } | |
| 1303 | |
| 1304 | |
| 1305 HeapWord* | |
| 1306 ConcurrentMarkSweepGeneration::allocation_limit_reached(Space* space, | |
| 1307 HeapWord* top, | |
| 1308 size_t word_sz) | |
| 1309 { | |
| 1310 return collector()->allocation_limit_reached(space, top, word_sz); | |
| 1311 } | |
| 1312 | |
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1313 // IMPORTANT: Notes on object size recognition in CMS. |
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1314 // --------------------------------------------------- |
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1315 // A block of storage in the CMS generation is always in |
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1316 // one of three states. A free block (FREE), an allocated |
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1317 // object (OBJECT) whose size() method reports the correct size, |
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1318 // and an intermediate state (TRANSIENT) in which its size cannot |
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1319 // be accurately determined. |
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1320 // STATE IDENTIFICATION: (32 bit and 64 bit w/o COOPS) |
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1321 // ----------------------------------------------------- |
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1322 // FREE: klass_word & 1 == 1; mark_word holds block size |
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1323 // |
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1324 // OBJECT: klass_word installed; klass_word != 0 && klass_word & 1 == 0; |
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1325 // obj->size() computes correct size |
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1326 // |
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1327 // TRANSIENT: klass_word == 0; size is indeterminate until we become an OBJECT |
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1328 // |
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1329 // STATE IDENTIFICATION: (64 bit+COOPS) |
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1330 // ------------------------------------ |
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1331 // FREE: mark_word & CMS_FREE_BIT == 1; mark_word & ~CMS_FREE_BIT gives block_size |
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1332 // |
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1333 // OBJECT: klass_word installed; klass_word != 0; |
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1334 // obj->size() computes correct size |
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1335 // |
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1336 // TRANSIENT: klass_word == 0; size is indeterminate until we become an OBJECT |
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1337 // |
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1338 // |
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1339 // STATE TRANSITION DIAGRAM |
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1340 // |
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1341 // mut / parnew mut / parnew |
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1342 // FREE --------------------> TRANSIENT ---------------------> OBJECT --| |
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1343 // ^ | |
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1344 // |------------------------ DEAD <------------------------------------| |
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1345 // sweep mut |
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1346 // |
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1347 // While a block is in TRANSIENT state its size cannot be determined |
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1348 // so readers will either need to come back later or stall until |
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1349 // the size can be determined. Note that for the case of direct |
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1350 // allocation, P-bits, when available, may be used to determine the |
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1351 // size of an object that may not yet have been initialized. |
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1352 |
| 0 | 1353 // Things to support parallel young-gen collection. |
| 1354 oop | |
| 1355 ConcurrentMarkSweepGeneration::par_promote(int thread_num, | |
| 1356 oop old, markOop m, | |
| 1357 size_t word_sz) { | |
| 1358 #ifndef PRODUCT | |
| 1359 if (Universe::heap()->promotion_should_fail()) { | |
| 1360 return NULL; | |
| 1361 } | |
| 1362 #endif // #ifndef PRODUCT | |
| 1363 | |
| 1364 CMSParGCThreadState* ps = _par_gc_thread_states[thread_num]; | |
| 1365 PromotionInfo* promoInfo = &ps->promo; | |
| 1366 // if we are tracking promotions, then first ensure space for | |
| 1367 // promotion (including spooling space for saving header if necessary). | |
| 1368 // then allocate and copy, then track promoted info if needed. | |
| 1369 // When tracking (see PromotionInfo::track()), the mark word may | |
| 1370 // be displaced and in this case restoration of the mark word | |
| 1371 // occurs in the (oop_since_save_marks_)iterate phase. | |
| 1372 if (promoInfo->tracking() && !promoInfo->ensure_spooling_space()) { | |
| 1373 // Out of space for allocating spooling buffers; | |
| 1374 // try expanding and allocating spooling buffers. | |
| 1375 if (!expand_and_ensure_spooling_space(promoInfo)) { | |
| 1376 return NULL; | |
| 1377 } | |
| 1378 } | |
| 1379 assert(promoInfo->has_spooling_space(), "Control point invariant"); | |
|
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1380 const size_t alloc_sz = CompactibleFreeListSpace::adjustObjectSize(word_sz); |
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1381 HeapWord* obj_ptr = ps->lab.alloc(alloc_sz); |
| 0 | 1382 if (obj_ptr == NULL) { |
|
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1383 obj_ptr = expand_and_par_lab_allocate(ps, alloc_sz); |
| 0 | 1384 if (obj_ptr == NULL) { |
| 1385 return NULL; | |
| 1386 } | |
| 1387 } | |
| 1388 oop obj = oop(obj_ptr); | |
|
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1389 OrderAccess::storestore(); |
| 187 | 1390 assert(obj->klass_or_null() == NULL, "Object should be uninitialized here."); |
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1391 assert(!((FreeChunk*)obj_ptr)->is_free(), "Error, block will look free but show wrong size"); |
|
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1392 // IMPORTANT: See note on object initialization for CMS above. |
| 0 | 1393 // Otherwise, copy the object. Here we must be careful to insert the |
| 1394 // klass pointer last, since this marks the block as an allocated object. | |
| 187 | 1395 // Except with compressed oops it's the mark word. |
| 0 | 1396 HeapWord* old_ptr = (HeapWord*)old; |
|
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1397 // Restore the mark word copied above. |
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1398 obj->set_mark(m); |
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1399 assert(obj->klass_or_null() == NULL, "Object should be uninitialized here."); |
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1400 assert(!((FreeChunk*)obj_ptr)->is_free(), "Error, block will look free but show wrong size"); |
|
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1401 OrderAccess::storestore(); |
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1402 |
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1403 if (UseCompressedKlassPointers) { |
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1404 // Copy gap missed by (aligned) header size calculation below |
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1405 obj->set_klass_gap(old->klass_gap()); |
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1406 } |
| 0 | 1407 if (word_sz > (size_t)oopDesc::header_size()) { |
| 1408 Copy::aligned_disjoint_words(old_ptr + oopDesc::header_size(), | |
| 1409 obj_ptr + oopDesc::header_size(), | |
| 1410 word_sz - oopDesc::header_size()); | |
| 1411 } | |
| 187 | 1412 |
| 0 | 1413 // Now we can track the promoted object, if necessary. We take care |
| 1521 | 1414 // to delay the transition from uninitialized to full object |
| 0 | 1415 // (i.e., insertion of klass pointer) until after, so that it |
| 1416 // atomically becomes a promoted object. | |
| 1417 if (promoInfo->tracking()) { | |
| 1418 promoInfo->track((PromotedObject*)obj, old->klass()); | |
| 1419 } | |
|
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1420 assert(obj->klass_or_null() == NULL, "Object should be uninitialized here."); |
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1421 assert(!((FreeChunk*)obj_ptr)->is_free(), "Error, block will look free but show wrong size"); |
|
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1422 assert(old->is_oop(), "Will use and dereference old klass ptr below"); |
| 187 | 1423 |
| 1424 // Finally, install the klass pointer (this should be volatile). | |
|
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1425 OrderAccess::storestore(); |
| 0 | 1426 obj->set_klass(old->klass()); |
|
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1427 // We should now be able to calculate the right size for this object |
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1428 assert(obj->is_oop() && obj->size() == (int)word_sz, "Error, incorrect size computed for promoted object"); |
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1429 |
| 0 | 1430 collector()->promoted(true, // parallel |
| 1431 obj_ptr, old->is_objArray(), word_sz); | |
| 1432 | |
| 1433 NOT_PRODUCT( | |
|
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1434 Atomic::inc_ptr(&_numObjectsPromoted); |
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1435 Atomic::add_ptr(alloc_sz, &_numWordsPromoted); |
| 0 | 1436 ) |
| 1437 | |
| 1438 return obj; | |
| 1439 } | |
| 1440 | |
| 1441 void | |
| 1442 ConcurrentMarkSweepGeneration:: | |
| 1443 par_promote_alloc_undo(int thread_num, | |
| 1444 HeapWord* obj, size_t word_sz) { | |
| 1445 // CMS does not support promotion undo. | |
| 1446 ShouldNotReachHere(); | |
| 1447 } | |
| 1448 | |
| 1449 void | |
| 1450 ConcurrentMarkSweepGeneration:: | |
| 1451 par_promote_alloc_done(int thread_num) { | |
| 1452 CMSParGCThreadState* ps = _par_gc_thread_states[thread_num]; | |
|
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1453 ps->lab.retire(thread_num); |
| 0 | 1454 } |
| 1455 | |
| 1456 void | |
| 1457 ConcurrentMarkSweepGeneration:: | |
| 1458 par_oop_since_save_marks_iterate_done(int thread_num) { | |
| 1459 CMSParGCThreadState* ps = _par_gc_thread_states[thread_num]; | |
| 1460 ParScanWithoutBarrierClosure* dummy_cl = NULL; | |
| 1461 ps->promo.promoted_oops_iterate_nv(dummy_cl); | |
| 1462 } | |
| 1463 | |
| 1464 bool ConcurrentMarkSweepGeneration::should_collect(bool full, | |
| 1465 size_t size, | |
| 1466 bool tlab) | |
| 1467 { | |
| 1468 // We allow a STW collection only if a full | |
| 1469 // collection was requested. | |
| 1470 return full || should_allocate(size, tlab); // FIX ME !!! | |
| 1471 // This and promotion failure handling are connected at the | |
| 1472 // hip and should be fixed by untying them. | |
| 1473 } | |
| 1474 | |
| 1475 bool CMSCollector::shouldConcurrentCollect() { | |
| 1476 if (_full_gc_requested) { | |
| 1477 if (Verbose && PrintGCDetails) { | |
| 1478 gclog_or_tty->print_cr("CMSCollector: collect because of explicit " | |
|
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1479 " gc request (or gc_locker)"); |
| 0 | 1480 } |
| 1481 return true; | |
| 1482 } | |
| 1483 | |
| 1484 // For debugging purposes, change the type of collection. | |
| 1485 // If the rotation is not on the concurrent collection | |
| 1486 // type, don't start a concurrent collection. | |
| 1487 NOT_PRODUCT( | |
| 1488 if (RotateCMSCollectionTypes && | |
| 1489 (_cmsGen->debug_collection_type() != | |
| 1490 ConcurrentMarkSweepGeneration::Concurrent_collection_type)) { | |
| 1491 assert(_cmsGen->debug_collection_type() != | |
| 1492 ConcurrentMarkSweepGeneration::Unknown_collection_type, | |
| 1493 "Bad cms collection type"); | |
| 1494 return false; | |
| 1495 } | |
| 1496 ) | |
| 1497 | |
| 1498 FreelistLocker x(this); | |
| 1499 // ------------------------------------------------------------------ | |
| 1500 // Print out lots of information which affects the initiation of | |
| 1501 // a collection. | |
| 1502 if (PrintCMSInitiationStatistics && stats().valid()) { | |
| 1503 gclog_or_tty->print("CMSCollector shouldConcurrentCollect: "); | |
| 1504 gclog_or_tty->stamp(); | |
| 1505 gclog_or_tty->print_cr(""); | |
| 1506 stats().print_on(gclog_or_tty); | |
| 1507 gclog_or_tty->print_cr("time_until_cms_gen_full %3.7f", | |
| 1508 stats().time_until_cms_gen_full()); | |
| 1509 gclog_or_tty->print_cr("free="SIZE_FORMAT, _cmsGen->free()); | |
| 1510 gclog_or_tty->print_cr("contiguous_available="SIZE_FORMAT, | |
| 1511 _cmsGen->contiguous_available()); | |
| 1512 gclog_or_tty->print_cr("promotion_rate=%g", stats().promotion_rate()); | |
| 1513 gclog_or_tty->print_cr("cms_allocation_rate=%g", stats().cms_allocation_rate()); | |
| 1514 gclog_or_tty->print_cr("occupancy=%3.7f", _cmsGen->occupancy()); | |
|
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1515 gclog_or_tty->print_cr("initiatingOccupancy=%3.7f", _cmsGen->initiating_occupancy()); |
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1516 gclog_or_tty->print_cr("metadata initialized %d", |
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1517 MetaspaceGC::should_concurrent_collect()); |
| 0 | 1518 } |
| 1519 // ------------------------------------------------------------------ | |
| 1520 | |
| 1521 // If the estimated time to complete a cms collection (cms_duration()) | |
| 1522 // is less than the estimated time remaining until the cms generation | |
| 1523 // is full, start a collection. | |
| 1524 if (!UseCMSInitiatingOccupancyOnly) { | |
| 1525 if (stats().valid()) { | |
| 1526 if (stats().time_until_cms_start() == 0.0) { | |
| 1527 return true; | |
| 1528 } | |
| 1529 } else { | |
| 1530 // We want to conservatively collect somewhat early in order | |
| 1531 // to try and "bootstrap" our CMS/promotion statistics; | |
| 1532 // this branch will not fire after the first successful CMS | |
| 1533 // collection because the stats should then be valid. | |
| 1534 if (_cmsGen->occupancy() >= _bootstrap_occupancy) { | |
| 1535 if (Verbose && PrintGCDetails) { | |
| 1536 gclog_or_tty->print_cr( | |
| 1537 " CMSCollector: collect for bootstrapping statistics:" | |
| 1538 " occupancy = %f, boot occupancy = %f", _cmsGen->occupancy(), | |
| 1539 _bootstrap_occupancy); | |
| 1540 } | |
| 1541 return true; | |
| 1542 } | |
| 1543 } | |
| 1544 } | |
| 1545 | |
|
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1546 // Otherwise, we start a collection cycle if |
| 0 | 1547 // old gen want a collection cycle started. Each may use |
| 1548 // an appropriate criterion for making this decision. | |
| 1549 // XXX We need to make sure that the gen expansion | |
|
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1550 // criterion dovetails well with this. XXX NEED TO FIX THIS |
|
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1551 if (_cmsGen->should_concurrent_collect()) { |
| 0 | 1552 if (Verbose && PrintGCDetails) { |
| 1553 gclog_or_tty->print_cr("CMS old gen initiated"); | |
| 1554 } | |
| 1555 return true; | |
| 1556 } | |
| 1557 | |
|
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1558 // We start a collection if we believe an incremental collection may fail; |
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1559 // this is not likely to be productive in practice because it's probably too |
|
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1560 // late anyway. |
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1561 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
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1562 assert(gch->collector_policy()->is_two_generation_policy(), |
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1563 "You may want to check the correctness of the following"); |
|
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1564 if (gch->incremental_collection_will_fail(true /* consult_young */)) { |
|
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1565 if (Verbose && PrintGCDetails) { |
|
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1566 gclog_or_tty->print("CMSCollector: collect because incremental collection will fail "); |
| 0 | 1567 } |
| 1568 return true; | |
| 1569 } | |
| 1570 | |
|
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1571 if (MetaspaceGC::should_concurrent_collect()) { |
|
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1572 if (Verbose && PrintGCDetails) { |
|
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1573 gclog_or_tty->print("CMSCollector: collect for metadata allocation "); |
|
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1574 } |
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1575 return true; |
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1576 } |
|
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1577 |
| 0 | 1578 return false; |
| 1579 } | |
| 1580 | |
| 1581 // Clear _expansion_cause fields of constituent generations | |
| 1582 void CMSCollector::clear_expansion_cause() { | |
| 1583 _cmsGen->clear_expansion_cause(); | |
| 1584 } | |
| 1585 | |
|
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1586 // We should be conservative in starting a collection cycle. To |
|
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1587 // start too eagerly runs the risk of collecting too often in the |
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1588 // extreme. To collect too rarely falls back on full collections, |
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1589 // which works, even if not optimum in terms of concurrent work. |
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1590 // As a work around for too eagerly collecting, use the flag |
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1591 // UseCMSInitiatingOccupancyOnly. This also has the advantage of |
|
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1592 // giving the user an easily understandable way of controlling the |
|
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1593 // collections. |
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1594 // We want to start a new collection cycle if any of the following |
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1595 // conditions hold: |
|
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1596 // . our current occupancy exceeds the configured initiating occupancy |
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1597 // for this generation, or |
|
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1598 // . we recently needed to expand this space and have not, since that |
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1599 // expansion, done a collection of this generation, or |
|
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1600 // . the underlying space believes that it may be a good idea to initiate |
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1601 // a concurrent collection (this may be based on criteria such as the |
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1602 // following: the space uses linear allocation and linear allocation is |
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1603 // going to fail, or there is believed to be excessive fragmentation in |
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1604 // the generation, etc... or ... |
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1605 // [.(currently done by CMSCollector::shouldConcurrentCollect() only for |
|
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1606 // the case of the old generation; see CR 6543076): |
|
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1607 // we may be approaching a point at which allocation requests may fail because |
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1608 // we will be out of sufficient free space given allocation rate estimates.] |
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1609 bool ConcurrentMarkSweepGeneration::should_concurrent_collect() const { |
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1610 |
| 0 | 1611 assert_lock_strong(freelistLock()); |
|
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1612 if (occupancy() > initiating_occupancy()) { |
| 0 | 1613 if (PrintGCDetails && Verbose) { |
| 1614 gclog_or_tty->print(" %s: collect because of occupancy %f / %f ", | |
|
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1615 short_name(), occupancy(), initiating_occupancy()); |
| 0 | 1616 } |
| 1617 return true; | |
| 1618 } | |
| 1619 if (UseCMSInitiatingOccupancyOnly) { | |
| 1620 return false; | |
| 1621 } | |
| 1622 if (expansion_cause() == CMSExpansionCause::_satisfy_allocation) { | |
| 1623 if (PrintGCDetails && Verbose) { | |
| 1624 gclog_or_tty->print(" %s: collect because expanded for allocation ", | |
| 1625 short_name()); | |
| 1626 } | |
| 1627 return true; | |
| 1628 } | |
|
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1629 if (_cmsSpace->should_concurrent_collect()) { |
| 0 | 1630 if (PrintGCDetails && Verbose) { |
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1631 gclog_or_tty->print(" %s: collect because cmsSpace says so ", |
| 0 | 1632 short_name()); |
| 1633 } | |
| 1634 return true; | |
| 1635 } | |
| 1636 return false; | |
| 1637 } | |
| 1638 | |
| 1639 void ConcurrentMarkSweepGeneration::collect(bool full, | |
| 1640 bool clear_all_soft_refs, | |
| 1641 size_t size, | |
| 1642 bool tlab) | |
| 1643 { | |
| 1644 collector()->collect(full, clear_all_soft_refs, size, tlab); | |
| 1645 } | |
| 1646 | |
| 1647 void CMSCollector::collect(bool full, | |
| 1648 bool clear_all_soft_refs, | |
| 1649 size_t size, | |
| 1650 bool tlab) | |
| 1651 { | |
| 1652 if (!UseCMSCollectionPassing && _collectorState > Idling) { | |
| 1653 // For debugging purposes skip the collection if the state | |
| 1654 // is not currently idle | |
| 1655 if (TraceCMSState) { | |
| 1656 gclog_or_tty->print_cr("Thread " INTPTR_FORMAT " skipped full:%d CMS state %d", | |
| 1657 Thread::current(), full, _collectorState); | |
| 1658 } | |
| 1659 return; | |
| 1660 } | |
| 1661 | |
| 1662 // The following "if" branch is present for defensive reasons. | |
| 1663 // In the current uses of this interface, it can be replaced with: | |
| 1664 // assert(!GC_locker.is_active(), "Can't be called otherwise"); | |
| 1665 // But I am not placing that assert here to allow future | |
| 1666 // generality in invoking this interface. | |
| 1667 if (GC_locker::is_active()) { | |
| 1668 // A consistency test for GC_locker | |
| 1669 assert(GC_locker::needs_gc(), "Should have been set already"); | |
| 1670 // Skip this foreground collection, instead | |
| 1671 // expanding the heap if necessary. | |
| 1672 // Need the free list locks for the call to free() in compute_new_size() | |
| 1673 compute_new_size(); | |
| 1674 return; | |
| 1675 } | |
| 1676 acquire_control_and_collect(full, clear_all_soft_refs); | |
| 1677 _full_gcs_since_conc_gc++; | |
| 1678 | |
| 1679 } | |
| 1680 | |
| 1681 void CMSCollector::request_full_gc(unsigned int full_gc_count) { | |
| 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; | |
| 1687 CGC_lock->notify(); // nudge CMS thread | |
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1688 } else { |
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1689 assert(gc_count > full_gc_count, "Error: causal loop"); |
| 0 | 1690 } |
| 1691 } | |
| 1692 | |
| 1693 | |
| 1694 // The foreground and background collectors need to coordinate in order | |
| 1695 // to make sure that they do not mutually interfere with CMS collections. | |
| 1696 // When a background collection is active, | |
| 1697 // the foreground collector may need to take over (preempt) and | |
| 1698 // synchronously complete an ongoing collection. Depending on the | |
| 1699 // frequency of the background collections and the heap usage | |
| 1700 // of the application, this preemption can be seldom or frequent. | |
| 1701 // There are only certain | |
| 1702 // points in the background collection that the "collection-baton" | |
| 1703 // can be passed to the foreground collector. | |
| 1704 // | |
| 1705 // The foreground collector will wait for the baton before | |
| 1706 // starting any part of the collection. The foreground collector | |
| 1707 // will only wait at one location. | |
| 1708 // | |
| 1709 // The background collector will yield the baton before starting a new | |
| 1710 // phase of the collection (e.g., before initial marking, marking from roots, | |
| 1711 // precleaning, final re-mark, sweep etc.) This is normally done at the head | |
| 1712 // of the loop which switches the phases. The background collector does some | |
| 1713 // of the phases (initial mark, final re-mark) with the world stopped. | |
| 1714 // Because of locking involved in stopping the world, | |
| 1715 // the foreground collector should not block waiting for the background | |
| 1716 // collector when it is doing a stop-the-world phase. The background | |
| 1717 // collector will yield the baton at an additional point just before | |
| 1718 // it enters a stop-the-world phase. Once the world is stopped, the | |
| 1719 // background collector checks the phase of the collection. If the | |
| 1720 // phase has not changed, it proceeds with the collection. If the | |
| 1721 // phase has changed, it skips that phase of the collection. See | |
| 1722 // the comments on the use of the Heap_lock in collect_in_background(). | |
| 1723 // | |
| 1724 // Variable used in baton passing. | |
| 1725 // _foregroundGCIsActive - Set to true by the foreground collector when | |
| 1726 // it wants the baton. The foreground clears it when it has finished | |
| 1727 // the collection. | |
| 1728 // _foregroundGCShouldWait - Set to true by the background collector | |
| 1729 // when it is running. The foreground collector waits while | |
| 1730 // _foregroundGCShouldWait is true. | |
| 1731 // CGC_lock - monitor used to protect access to the above variables | |
| 1732 // and to notify the foreground and background collectors. | |
| 1733 // _collectorState - current state of the CMS collection. | |
| 1734 // | |
| 1735 // The foreground collector | |
| 1736 // acquires the CGC_lock | |
| 1737 // sets _foregroundGCIsActive | |
| 1738 // waits on the CGC_lock for _foregroundGCShouldWait to be false | |
| 1739 // various locks acquired in preparation for the collection | |
| 1740 // are released so as not to block the background collector | |
| 1741 // that is in the midst of a collection | |
| 1742 // proceeds with the collection | |
| 1743 // clears _foregroundGCIsActive | |
| 1744 // returns | |
| 1745 // | |
| 1746 // The background collector in a loop iterating on the phases of the | |
| 1747 // collection | |
| 1748 // acquires the CGC_lock | |
| 1749 // sets _foregroundGCShouldWait | |
| 1750 // if _foregroundGCIsActive is set | |
| 1751 // clears _foregroundGCShouldWait, notifies _CGC_lock | |
| 1752 // waits on _CGC_lock for _foregroundGCIsActive to become false | |
| 1753 // and exits the loop. | |
| 1754 // otherwise | |
| 1755 // proceed with that phase of the collection | |
| 1756 // if the phase is a stop-the-world phase, | |
| 1757 // yield the baton once more just before enqueueing | |
| 1758 // the stop-world CMS operation (executed by the VM thread). | |
| 1759 // returns after all phases of the collection are done | |
| 1760 // | |
| 1761 | |
| 1762 void CMSCollector::acquire_control_and_collect(bool full, | |
| 1763 bool clear_all_soft_refs) { | |
| 1764 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); | |
| 1765 assert(!Thread::current()->is_ConcurrentGC_thread(), | |
| 1766 "shouldn't try to acquire control from self!"); | |
| 1767 | |
| 1768 // Start the protocol for acquiring control of the | |
| 1769 // collection from the background collector (aka CMS thread). | |
| 1770 assert(ConcurrentMarkSweepThread::vm_thread_has_cms_token(), | |
| 1771 "VM thread should have CMS token"); | |
| 1772 // Remember the possibly interrupted state of an ongoing | |
| 1773 // concurrent collection | |
| 1774 CollectorState first_state = _collectorState; | |
| 1775 | |
| 1776 // Signal to a possibly ongoing concurrent collection that | |
| 1777 // we want to do a foreground collection. | |
| 1778 _foregroundGCIsActive = true; | |
| 1779 | |
| 1780 // Disable incremental mode during a foreground collection. | |
| 1781 ICMSDisabler icms_disabler; | |
| 1782 | |
| 1783 // release locks and wait for a notify from the background collector | |
| 1784 // releasing the locks in only necessary for phases which | |
| 1785 // do yields to improve the granularity of the collection. | |
| 1786 assert_lock_strong(bitMapLock()); | |
| 1787 // We need to lock the Free list lock for the space that we are | |
| 1788 // currently collecting. | |
| 1789 assert(haveFreelistLocks(), "Must be holding free list locks"); | |
| 1790 bitMapLock()->unlock(); | |
| 1791 releaseFreelistLocks(); | |
| 1792 { | |
| 1793 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
| 1794 if (_foregroundGCShouldWait) { | |
| 1795 // We are going to be waiting for action for the CMS thread; | |
| 1796 // it had better not be gone (for instance at shutdown)! | |
| 1797 assert(ConcurrentMarkSweepThread::cmst() != NULL, | |
| 1798 "CMS thread must be running"); | |
| 1799 // Wait here until the background collector gives us the go-ahead | |
| 1800 ConcurrentMarkSweepThread::clear_CMS_flag( | |
| 1801 ConcurrentMarkSweepThread::CMS_vm_has_token); // release token | |
| 1802 // Get a possibly blocked CMS thread going: | |
| 1803 // Note that we set _foregroundGCIsActive true above, | |
| 1804 // without protection of the CGC_lock. | |
| 1805 CGC_lock->notify(); | |
| 1806 assert(!ConcurrentMarkSweepThread::vm_thread_wants_cms_token(), | |
| 1807 "Possible deadlock"); | |
| 1808 while (_foregroundGCShouldWait) { | |
| 1809 // wait for notification | |
| 1810 CGC_lock->wait(Mutex::_no_safepoint_check_flag); | |
| 1811 // Possibility of delay/starvation here, since CMS token does | |
| 1812 // not know to give priority to VM thread? Actually, i think | |
| 1813 // there wouldn't be any delay/starvation, but the proof of | |
| 1814 // that "fact" (?) appears non-trivial. XXX 20011219YSR | |
| 1815 } | |
| 1816 ConcurrentMarkSweepThread::set_CMS_flag( | |
| 1817 ConcurrentMarkSweepThread::CMS_vm_has_token); | |
| 1818 } | |
| 1819 } | |
| 1820 // The CMS_token is already held. Get back the other locks. | |
| 1821 assert(ConcurrentMarkSweepThread::vm_thread_has_cms_token(), | |
| 1822 "VM thread should have CMS token"); | |
| 1823 getFreelistLocks(); | |
| 1824 bitMapLock()->lock_without_safepoint_check(); | |
| 1825 if (TraceCMSState) { | |
| 1826 gclog_or_tty->print_cr("CMS foreground collector has asked for control " | |
| 1827 INTPTR_FORMAT " with first state %d", Thread::current(), first_state); | |
| 1828 gclog_or_tty->print_cr(" gets control with state %d", _collectorState); | |
| 1829 } | |
| 1830 | |
| 1831 // Check if we need to do a compaction, or if not, whether | |
| 1832 // we need to start the mark-sweep from scratch. | |
| 1833 bool should_compact = false; | |
| 1834 bool should_start_over = false; | |
| 1835 decide_foreground_collection_type(clear_all_soft_refs, | |
| 1836 &should_compact, &should_start_over); | |
| 1837 | |
| 1838 NOT_PRODUCT( | |
| 1839 if (RotateCMSCollectionTypes) { | |
| 1840 if (_cmsGen->debug_collection_type() == | |
| 1841 ConcurrentMarkSweepGeneration::MSC_foreground_collection_type) { | |
| 1842 should_compact = true; | |
| 1843 } else if (_cmsGen->debug_collection_type() == | |
| 1844 ConcurrentMarkSweepGeneration::MS_foreground_collection_type) { | |
| 1845 should_compact = false; | |
| 1846 } | |
| 1847 } | |
| 1848 ) | |
| 1849 | |
| 1850 if (PrintGCDetails && first_state > Idling) { | |
| 1851 GCCause::Cause cause = GenCollectedHeap::heap()->gc_cause(); | |
| 1852 if (GCCause::is_user_requested_gc(cause) || | |
| 1853 GCCause::is_serviceability_requested_gc(cause)) { | |
| 1854 gclog_or_tty->print(" (concurrent mode interrupted)"); | |
| 1855 } else { | |
| 1856 gclog_or_tty->print(" (concurrent mode failure)"); | |
| 1857 } | |
| 1858 } | |
| 1859 | |
| 1860 if (should_compact) { | |
| 1861 // If the collection is being acquired from the background | |
| 1862 // collector, there may be references on the discovered | |
| 1863 // references lists that have NULL referents (being those | |
| 1864 // that were concurrently cleared by a mutator) or | |
| 1865 // that are no longer active (having been enqueued concurrently | |
| 1866 // by the mutator). | |
| 1867 // Scrub the list of those references because Mark-Sweep-Compact | |
| 1868 // code assumes referents are not NULL and that all discovered | |
| 1869 // Reference objects are active. | |
| 1870 ref_processor()->clean_up_discovered_references(); | |
| 1871 | |
| 1872 do_compaction_work(clear_all_soft_refs); | |
| 1873 | |
| 1874 // Has the GC time limit been exceeded? | |
|
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1875 DefNewGeneration* young_gen = _young_gen->as_DefNewGeneration(); |
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1876 size_t max_eden_size = young_gen->max_capacity() - |
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1877 young_gen->to()->capacity() - |
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1878 young_gen->from()->capacity(); |
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1879 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
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1880 GCCause::Cause gc_cause = gch->gc_cause(); |
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1881 size_policy()->check_gc_overhead_limit(_young_gen->used(), |
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1882 young_gen->eden()->used(), |
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1883 _cmsGen->max_capacity(), |
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1884 max_eden_size, |
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1885 full, |
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1886 gc_cause, |
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1887 gch->collector_policy()); |
| 0 | 1888 } else { |
| 1889 do_mark_sweep_work(clear_all_soft_refs, first_state, | |
| 1890 should_start_over); | |
| 1891 } | |
| 1892 // Reset the expansion cause, now that we just completed | |
| 1893 // a collection cycle. | |
| 1894 clear_expansion_cause(); | |
| 1895 _foregroundGCIsActive = false; | |
| 1896 return; | |
| 1897 } | |
| 1898 | |
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1899 // Resize the tenured generation |
| 0 | 1900 // after obtaining the free list locks for the |
| 1901 // two generations. | |
| 1902 void CMSCollector::compute_new_size() { | |
| 1903 assert_locked_or_safepoint(Heap_lock); | |
| 1904 FreelistLocker z(this); | |
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1905 MetaspaceGC::compute_new_size(); |
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1906 _cmsGen->compute_new_size_free_list(); |
| 0 | 1907 } |
| 1908 | |
| 1909 // A work method used by foreground collection to determine | |
| 1910 // what type of collection (compacting or not, continuing or fresh) | |
| 1911 // it should do. | |
| 1912 // NOTE: the intent is to make UseCMSCompactAtFullCollection | |
| 1913 // and CMSCompactWhenClearAllSoftRefs the default in the future | |
| 1914 // and do away with the flags after a suitable period. | |
| 1915 void CMSCollector::decide_foreground_collection_type( | |
| 1916 bool clear_all_soft_refs, bool* should_compact, | |
| 1917 bool* should_start_over) { | |
| 1918 // Normally, we'll compact only if the UseCMSCompactAtFullCollection | |
| 1919 // flag is set, and we have either requested a System.gc() or | |
| 1920 // the number of full gc's since the last concurrent cycle | |
| 1921 // has exceeded the threshold set by CMSFullGCsBeforeCompaction, | |
| 1922 // or if an incremental collection has failed | |
| 1923 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 1924 assert(gch->collector_policy()->is_two_generation_policy(), | |
| 1925 "You may want to check the correctness of the following"); | |
| 1926 // Inform cms gen if this was due to partial collection failing. | |
| 1927 // The CMS gen may use this fact to determine its expansion policy. | |
|
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1928 if (gch->incremental_collection_will_fail(false /* don't consult_young */)) { |
| 0 | 1929 assert(!_cmsGen->incremental_collection_failed(), |
| 1930 "Should have been noticed, reacted to and cleared"); | |
| 1931 _cmsGen->set_incremental_collection_failed(); | |
| 1932 } | |
| 1933 *should_compact = | |
| 1934 UseCMSCompactAtFullCollection && | |
| 1935 ((_full_gcs_since_conc_gc >= CMSFullGCsBeforeCompaction) || | |
| 1936 GCCause::is_user_requested_gc(gch->gc_cause()) || | |
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1937 gch->incremental_collection_will_fail(true /* consult_young */)); |
| 0 | 1938 *should_start_over = false; |
| 1939 if (clear_all_soft_refs && !*should_compact) { | |
| 1940 // We are about to do a last ditch collection attempt | |
| 1941 // so it would normally make sense to do a compaction | |
| 1942 // to reclaim as much space as possible. | |
| 1943 if (CMSCompactWhenClearAllSoftRefs) { | |
| 1944 // Default: The rationale is that in this case either | |
| 1945 // we are past the final marking phase, in which case | |
| 1946 // we'd have to start over, or so little has been done | |
| 1947 // that there's little point in saving that work. Compaction | |
| 1948 // appears to be the sensible choice in either case. | |
| 1949 *should_compact = true; | |
| 1950 } else { | |
| 1951 // We have been asked to clear all soft refs, but not to | |
| 1952 // compact. Make sure that we aren't past the final checkpoint | |
| 1953 // phase, for that is where we process soft refs. If we are already | |
| 1954 // past that phase, we'll need to redo the refs discovery phase and | |
| 1955 // if necessary clear soft refs that weren't previously | |
| 1956 // cleared. We do so by remembering the phase in which | |
| 1957 // we came in, and if we are past the refs processing | |
| 1958 // phase, we'll choose to just redo the mark-sweep | |
| 1959 // collection from scratch. | |
| 1960 if (_collectorState > FinalMarking) { | |
| 1961 // We are past the refs processing phase; | |
| 1962 // start over and do a fresh synchronous CMS cycle | |
| 1963 _collectorState = Resetting; // skip to reset to start new cycle | |
| 1964 reset(false /* == !asynch */); | |
| 1965 *should_start_over = true; | |
| 1966 } // else we can continue a possibly ongoing current cycle | |
| 1967 } | |
| 1968 } | |
| 1969 } | |
| 1970 | |
| 1971 // A work method used by the foreground collector to do | |
| 1972 // a mark-sweep-compact. | |
| 1973 void CMSCollector::do_compaction_work(bool clear_all_soft_refs) { | |
| 1974 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 1975 TraceTime t("CMS:MSC ", PrintGCDetails && Verbose, true, gclog_or_tty); | |
| 1976 if (PrintGC && Verbose && !(GCCause::is_user_requested_gc(gch->gc_cause()))) { | |
| 1977 gclog_or_tty->print_cr("Compact ConcurrentMarkSweepGeneration after %d " | |
| 1978 "collections passed to foreground collector", _full_gcs_since_conc_gc); | |
| 1979 } | |
| 1980 | |
| 1981 // Sample collection interval time and reset for collection pause. | |
| 1982 if (UseAdaptiveSizePolicy) { | |
| 1983 size_policy()->msc_collection_begin(); | |
| 1984 } | |
| 1985 | |
| 1986 // Temporarily widen the span of the weak reference processing to | |
| 1987 // the entire heap. | |
| 1988 MemRegion new_span(GenCollectedHeap::heap()->reserved_region()); | |
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1989 ReferenceProcessorSpanMutator rp_mut_span(ref_processor(), new_span); |
| 0 | 1990 // Temporarily, clear the "is_alive_non_header" field of the |
| 1991 // reference processor. | |
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1992 ReferenceProcessorIsAliveMutator rp_mut_closure(ref_processor(), NULL); |
| 0 | 1993 // Temporarily make reference _processing_ single threaded (non-MT). |
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1994 ReferenceProcessorMTProcMutator rp_mut_mt_processing(ref_processor(), false); |
| 0 | 1995 // Temporarily make refs discovery atomic |
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1996 ReferenceProcessorAtomicMutator rp_mut_atomic(ref_processor(), true); |
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1997 // Temporarily make reference _discovery_ single threaded (non-MT) |
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1998 ReferenceProcessorMTDiscoveryMutator rp_mut_discovery(ref_processor(), false); |
| 0 | 1999 |
| 2000 ref_processor()->set_enqueuing_is_done(false); | |
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2001 ref_processor()->enable_discovery(false /*verify_disabled*/, false /*check_no_refs*/); |
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2002 ref_processor()->setup_policy(clear_all_soft_refs); |
| 0 | 2003 // If an asynchronous collection finishes, the _modUnionTable is |
| 2004 // all clear. If we are assuming the collection from an asynchronous | |
| 2005 // collection, clear the _modUnionTable. | |
| 2006 assert(_collectorState != Idling || _modUnionTable.isAllClear(), | |
| 2007 "_modUnionTable should be clear if the baton was not passed"); | |
| 2008 _modUnionTable.clear_all(); | |
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2009 assert(_collectorState != Idling || _ct->klass_rem_set()->mod_union_is_clear(), |
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2010 "mod union for klasses should be clear if the baton was passed"); |
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2011 _ct->klass_rem_set()->clear_mod_union(); |
| 0 | 2012 |
| 2013 // We must adjust the allocation statistics being maintained | |
| 2014 // in the free list space. We do so by reading and clearing | |
| 2015 // the sweep timer and updating the block flux rate estimates below. | |
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2016 assert(!_intra_sweep_timer.is_active(), "_intra_sweep_timer should be inactive"); |
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2017 if (_inter_sweep_timer.is_active()) { |
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2018 _inter_sweep_timer.stop(); |
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2019 // Note that we do not use this sample to update the _inter_sweep_estimate. |
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2020 _cmsGen->cmsSpace()->beginSweepFLCensus((float)(_inter_sweep_timer.seconds()), |
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2021 _inter_sweep_estimate.padded_average(), |
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2022 _intra_sweep_estimate.padded_average()); |
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2023 } |
| 0 | 2024 |
| 2025 GenMarkSweep::invoke_at_safepoint(_cmsGen->level(), | |
| 2026 ref_processor(), clear_all_soft_refs); | |
| 2027 #ifdef ASSERT | |
| 2028 CompactibleFreeListSpace* cms_space = _cmsGen->cmsSpace(); | |
| 2029 size_t free_size = cms_space->free(); | |
| 2030 assert(free_size == | |
| 2031 pointer_delta(cms_space->end(), cms_space->compaction_top()) | |
| 2032 * HeapWordSize, | |
| 2033 "All the free space should be compacted into one chunk at top"); | |
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2034 assert(cms_space->dictionary()->total_chunk_size( |
| 0 | 2035 debug_only(cms_space->freelistLock())) == 0 || |
| 2036 cms_space->totalSizeInIndexedFreeLists() == 0, | |
| 2037 "All the free space should be in a single chunk"); | |
| 2038 size_t num = cms_space->totalCount(); | |
| 2039 assert((free_size == 0 && num == 0) || | |
| 2040 (free_size > 0 && (num == 1 || num == 2)), | |
| 2041 "There should be at most 2 free chunks after compaction"); | |
| 2042 #endif // ASSERT | |
| 2043 _collectorState = Resetting; | |
| 2044 assert(_restart_addr == NULL, | |
| 2045 "Should have been NULL'd before baton was passed"); | |
| 2046 reset(false /* == !asynch */); | |
| 2047 _cmsGen->reset_after_compaction(); | |
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2048 _concurrent_cycles_since_last_unload = 0; |
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2049 |
| 0 | 2050 // Clear any data recorded in the PLAB chunk arrays. |
| 2051 if (_survivor_plab_array != NULL) { | |
| 2052 reset_survivor_plab_arrays(); | |
| 2053 } | |
| 2054 | |
| 2055 // Adjust the per-size allocation stats for the next epoch. | |
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2056 _cmsGen->cmsSpace()->endSweepFLCensus(sweep_count() /* fake */); |
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2057 // Restart the "inter sweep timer" for the next epoch. |
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2058 _inter_sweep_timer.reset(); |
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2059 _inter_sweep_timer.start(); |
| 0 | 2060 |
| 2061 // Sample collection pause time and reset for collection interval. | |
| 2062 if (UseAdaptiveSizePolicy) { | |
| 2063 size_policy()->msc_collection_end(gch->gc_cause()); | |
| 2064 } | |
| 2065 | |
| 2066 // For a mark-sweep-compact, compute_new_size() will be called | |
| 2067 // in the heap's do_collection() method. | |
| 2068 } | |
| 2069 | |
| 2070 // A work method used by the foreground collector to do | |
| 2071 // a mark-sweep, after taking over from a possibly on-going | |
| 2072 // concurrent mark-sweep collection. | |
| 2073 void CMSCollector::do_mark_sweep_work(bool clear_all_soft_refs, | |
| 2074 CollectorState first_state, bool should_start_over) { | |
| 2075 if (PrintGC && Verbose) { | |
| 2076 gclog_or_tty->print_cr("Pass concurrent collection to foreground " | |
| 2077 "collector with count %d", | |
| 2078 _full_gcs_since_conc_gc); | |
| 2079 } | |
| 2080 switch (_collectorState) { | |
| 2081 case Idling: | |
| 2082 if (first_state == Idling || should_start_over) { | |
| 2083 // The background GC was not active, or should | |
| 2084 // restarted from scratch; start the cycle. | |
| 2085 _collectorState = InitialMarking; | |
| 2086 } | |
| 2087 // If first_state was not Idling, then a background GC | |
| 2088 // was in progress and has now finished. No need to do it | |
| 2089 // again. Leave the state as Idling. | |
| 2090 break; | |
| 2091 case Precleaning: | |
| 2092 // In the foreground case don't do the precleaning since | |
| 2093 // it is not done concurrently and there is extra work | |
| 2094 // required. | |
| 2095 _collectorState = FinalMarking; | |
| 2096 } | |
| 2097 collect_in_foreground(clear_all_soft_refs); | |
| 2098 | |
| 2099 // For a mark-sweep, compute_new_size() will be called | |
| 2100 // in the heap's do_collection() method. | |
| 2101 } | |
| 2102 | |
| 2103 | |
| 2104 void CMSCollector::getFreelistLocks() const { | |
| 2105 // Get locks for all free lists in all generations that this | |
| 2106 // collector is responsible for | |
| 2107 _cmsGen->freelistLock()->lock_without_safepoint_check(); | |
| 2108 } | |
| 2109 | |
| 2110 void CMSCollector::releaseFreelistLocks() const { | |
| 2111 // Release locks for all free lists in all generations that this | |
| 2112 // collector is responsible for | |
| 2113 _cmsGen->freelistLock()->unlock(); | |
| 2114 } | |
| 2115 | |
| 2116 bool CMSCollector::haveFreelistLocks() const { | |
| 2117 // Check locks for all free lists in all generations that this | |
| 2118 // collector is responsible for | |
| 2119 assert_lock_strong(_cmsGen->freelistLock()); | |
| 2120 PRODUCT_ONLY(ShouldNotReachHere()); | |
| 2121 return true; | |
| 2122 } | |
| 2123 | |
| 2124 // A utility class that is used by the CMS collector to | |
| 2125 // temporarily "release" the foreground collector from its | |
| 2126 // usual obligation to wait for the background collector to | |
| 2127 // complete an ongoing phase before proceeding. | |
| 2128 class ReleaseForegroundGC: public StackObj { | |
| 2129 private: | |
| 2130 CMSCollector* _c; | |
| 2131 public: | |
| 2132 ReleaseForegroundGC(CMSCollector* c) : _c(c) { | |
| 2133 assert(_c->_foregroundGCShouldWait, "Else should not need to call"); | |
| 2134 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
| 2135 // allow a potentially blocked foreground collector to proceed | |
| 2136 _c->_foregroundGCShouldWait = false; | |
| 2137 if (_c->_foregroundGCIsActive) { | |
| 2138 CGC_lock->notify(); | |
| 2139 } | |
| 2140 assert(!ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 2141 "Possible deadlock"); | |
| 2142 } | |
| 2143 | |
| 2144 ~ReleaseForegroundGC() { | |
| 2145 assert(!_c->_foregroundGCShouldWait, "Usage protocol violation?"); | |
| 2146 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
| 2147 _c->_foregroundGCShouldWait = true; | |
| 2148 } | |
| 2149 }; | |
| 2150 | |
| 2151 // There are separate collect_in_background and collect_in_foreground because of | |
| 2152 // the different locking requirements of the background collector and the | |
| 2153 // foreground collector. There was originally an attempt to share | |
| 2154 // one "collect" method between the background collector and the foreground | |
| 2155 // collector but the if-then-else required made it cleaner to have | |
| 2156 // separate methods. | |
| 2157 void CMSCollector::collect_in_background(bool clear_all_soft_refs) { | |
| 2158 assert(Thread::current()->is_ConcurrentGC_thread(), | |
| 2159 "A CMS asynchronous collection is only allowed on a CMS thread."); | |
| 2160 | |
| 2161 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 2162 { | |
| 2163 bool safepoint_check = Mutex::_no_safepoint_check_flag; | |
| 2164 MutexLockerEx hl(Heap_lock, safepoint_check); | |
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2165 FreelistLocker fll(this); |
| 0 | 2166 MutexLockerEx x(CGC_lock, safepoint_check); |
| 2167 if (_foregroundGCIsActive || !UseAsyncConcMarkSweepGC) { | |
| 2168 // The foreground collector is active or we're | |
| 2169 // not using asynchronous collections. Skip this | |
| 2170 // background collection. | |
| 2171 assert(!_foregroundGCShouldWait, "Should be clear"); | |
| 2172 return; | |
| 2173 } else { | |
| 2174 assert(_collectorState == Idling, "Should be idling before start."); | |
| 2175 _collectorState = InitialMarking; | |
| 2176 // Reset the expansion cause, now that we are about to begin | |
| 2177 // a new cycle. | |
| 2178 clear_expansion_cause(); | |
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2179 |
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2180 // Clear the MetaspaceGC flag since a concurrent collection |
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2181 // is starting but also clear it after the collection. |
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2182 MetaspaceGC::set_should_concurrent_collect(false); |
| 0 | 2183 } |
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2184 // Decide if we want to enable class unloading as part of the |
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2185 // ensuing concurrent GC cycle. |
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2186 update_should_unload_classes(); |
| 0 | 2187 _full_gc_requested = false; // acks all outstanding full gc requests |
| 2188 // Signal that we are about to start a collection | |
| 2189 gch->increment_total_full_collections(); // ... starting a collection cycle | |
| 2190 _collection_count_start = gch->total_full_collections(); | |
| 2191 } | |
| 2192 | |
| 2193 // Used for PrintGC | |
| 2194 size_t prev_used; | |
| 2195 if (PrintGC && Verbose) { | |
| 2196 prev_used = _cmsGen->used(); // XXXPERM | |
| 2197 } | |
| 2198 | |
| 2199 // The change of the collection state is normally done at this level; | |
| 2200 // the exceptions are phases that are executed while the world is | |
| 2201 // stopped. For those phases the change of state is done while the | |
| 2202 // world is stopped. For baton passing purposes this allows the | |
| 2203 // background collector to finish the phase and change state atomically. | |
| 2204 // The foreground collector cannot wait on a phase that is done | |
| 2205 // while the world is stopped because the foreground collector already | |
| 2206 // has the world stopped and would deadlock. | |
| 2207 while (_collectorState != Idling) { | |
| 2208 if (TraceCMSState) { | |
| 2209 gclog_or_tty->print_cr("Thread " INTPTR_FORMAT " in CMS state %d", | |
| 2210 Thread::current(), _collectorState); | |
| 2211 } | |
| 2212 // The foreground collector | |
| 2213 // holds the Heap_lock throughout its collection. | |
| 2214 // holds the CMS token (but not the lock) | |
| 2215 // except while it is waiting for the background collector to yield. | |
| 2216 // | |
| 2217 // The foreground collector should be blocked (not for long) | |
| 2218 // if the background collector is about to start a phase | |
| 2219 // executed with world stopped. If the background | |
| 2220 // collector has already started such a phase, the | |
| 2221 // foreground collector is blocked waiting for the | |
| 2222 // Heap_lock. The stop-world phases (InitialMarking and FinalMarking) | |
| 2223 // are executed in the VM thread. | |
| 2224 // | |
| 2225 // The locking order is | |
| 2226 // PendingListLock (PLL) -- if applicable (FinalMarking) | |
| 2227 // Heap_lock (both this & PLL locked in VM_CMS_Operation::prologue()) | |
| 2228 // CMS token (claimed in | |
| 2229 // stop_world_and_do() --> | |
| 2230 // safepoint_synchronize() --> | |
| 2231 // CMSThread::synchronize()) | |
| 2232 | |
| 2233 { | |
| 2234 // Check if the FG collector wants us to yield. | |
| 2235 CMSTokenSync x(true); // is cms thread | |
| 2236 if (waitForForegroundGC()) { | |
| 2237 // We yielded to a foreground GC, nothing more to be | |
| 2238 // done this round. | |
| 2239 assert(_foregroundGCShouldWait == false, "We set it to false in " | |
| 2240 "waitForForegroundGC()"); | |
| 2241 if (TraceCMSState) { | |
| 2242 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT | |
| 2243 " exiting collection CMS state %d", | |
| 2244 Thread::current(), _collectorState); | |
| 2245 } | |
| 2246 return; | |
| 2247 } else { | |
| 2248 // The background collector can run but check to see if the | |
| 2249 // foreground collector has done a collection while the | |
| 2250 // background collector was waiting to get the CGC_lock | |
| 2251 // above. If yes, break so that _foregroundGCShouldWait | |
| 2252 // is cleared before returning. | |
| 2253 if (_collectorState == Idling) { | |
| 2254 break; | |
| 2255 } | |
| 2256 } | |
| 2257 } | |
| 2258 | |
| 2259 assert(_foregroundGCShouldWait, "Foreground collector, if active, " | |
| 2260 "should be waiting"); | |
| 2261 | |
| 2262 switch (_collectorState) { | |
| 2263 case InitialMarking: | |
| 2264 { | |
| 2265 ReleaseForegroundGC x(this); | |
| 2266 stats().record_cms_begin(); | |
| 2267 | |
| 2268 VM_CMS_Initial_Mark initial_mark_op(this); | |
| 2269 VMThread::execute(&initial_mark_op); | |
| 2270 } | |
| 2271 // The collector state may be any legal state at this point | |
| 2272 // since the background collector may have yielded to the | |
| 2273 // foreground collector. | |
| 2274 break; | |
| 2275 case Marking: | |
| 2276 // initial marking in checkpointRootsInitialWork has been completed | |
| 2277 if (markFromRoots(true)) { // we were successful | |
| 2278 assert(_collectorState == Precleaning, "Collector state should " | |
| 2279 "have changed"); | |
| 2280 } else { | |
| 2281 assert(_foregroundGCIsActive, "Internal state inconsistency"); | |
| 2282 } | |
| 2283 break; | |
| 2284 case Precleaning: | |
| 2285 if (UseAdaptiveSizePolicy) { | |
| 2286 size_policy()->concurrent_precleaning_begin(); | |
| 2287 } | |
| 2288 // marking from roots in markFromRoots has been completed | |
| 2289 preclean(); | |
| 2290 if (UseAdaptiveSizePolicy) { | |
| 2291 size_policy()->concurrent_precleaning_end(); | |
| 2292 } | |
| 2293 assert(_collectorState == AbortablePreclean || | |
| 2294 _collectorState == FinalMarking, | |
| 2295 "Collector state should have changed"); | |
| 2296 break; | |
| 2297 case AbortablePreclean: | |
| 2298 if (UseAdaptiveSizePolicy) { | |
| 2299 size_policy()->concurrent_phases_resume(); | |
| 2300 } | |
| 2301 abortable_preclean(); | |
| 2302 if (UseAdaptiveSizePolicy) { | |
| 2303 size_policy()->concurrent_precleaning_end(); | |
| 2304 } | |
| 2305 assert(_collectorState == FinalMarking, "Collector state should " | |
| 2306 "have changed"); | |
| 2307 break; | |
| 2308 case FinalMarking: | |
| 2309 { | |
| 2310 ReleaseForegroundGC x(this); | |
| 2311 | |
| 2312 VM_CMS_Final_Remark final_remark_op(this); | |
| 2313 VMThread::execute(&final_remark_op); | |
| 935 | 2314 } |
| 0 | 2315 assert(_foregroundGCShouldWait, "block post-condition"); |
| 2316 break; | |
| 2317 case Sweeping: | |
| 2318 if (UseAdaptiveSizePolicy) { | |
| 2319 size_policy()->concurrent_sweeping_begin(); | |
| 2320 } | |
| 2321 // final marking in checkpointRootsFinal has been completed | |
| 2322 sweep(true); | |
| 2323 assert(_collectorState == Resizing, "Collector state change " | |
| 2324 "to Resizing must be done under the free_list_lock"); | |
| 2325 _full_gcs_since_conc_gc = 0; | |
| 2326 | |
| 2327 // Stop the timers for adaptive size policy for the concurrent phases | |
| 2328 if (UseAdaptiveSizePolicy) { | |
| 2329 size_policy()->concurrent_sweeping_end(); | |
| 2330 size_policy()->concurrent_phases_end(gch->gc_cause(), | |
| 2331 gch->prev_gen(_cmsGen)->capacity(), | |
| 2332 _cmsGen->free()); | |
| 2333 } | |
| 2334 | |
| 2335 case Resizing: { | |
| 2336 // Sweeping has been completed... | |
| 2337 // At this point the background collection has completed. | |
| 2338 // Don't move the call to compute_new_size() down | |
| 2339 // into code that might be executed if the background | |
| 2340 // collection was preempted. | |
| 2341 { | |
| 2342 ReleaseForegroundGC x(this); // unblock FG collection | |
| 2343 MutexLockerEx y(Heap_lock, Mutex::_no_safepoint_check_flag); | |
| 2344 CMSTokenSync z(true); // not strictly needed. | |
| 2345 if (_collectorState == Resizing) { | |
| 2346 compute_new_size(); | |
| 2347 _collectorState = Resetting; | |
| 2348 } else { | |
| 2349 assert(_collectorState == Idling, "The state should only change" | |
| 2350 " because the foreground collector has finished the collection"); | |
| 2351 } | |
| 2352 } | |
| 2353 break; | |
| 2354 } | |
| 2355 case Resetting: | |
| 2356 // CMS heap resizing has been completed | |
| 2357 reset(true); | |
| 2358 assert(_collectorState == Idling, "Collector state should " | |
| 2359 "have changed"); | |
|
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2360 |
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2361 MetaspaceGC::set_should_concurrent_collect(false); |
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2362 |
| 0 | 2363 stats().record_cms_end(); |
| 2364 // Don't move the concurrent_phases_end() and compute_new_size() | |
| 2365 // calls to here because a preempted background collection | |
| 2366 // has it's state set to "Resetting". | |
| 2367 break; | |
| 2368 case Idling: | |
| 2369 default: | |
| 2370 ShouldNotReachHere(); | |
| 2371 break; | |
| 2372 } | |
| 2373 if (TraceCMSState) { | |
| 2374 gclog_or_tty->print_cr(" Thread " INTPTR_FORMAT " done - next CMS state %d", | |
| 2375 Thread::current(), _collectorState); | |
| 2376 } | |
| 2377 assert(_foregroundGCShouldWait, "block post-condition"); | |
| 2378 } | |
| 2379 | |
| 2380 // Should this be in gc_epilogue? | |
| 2381 collector_policy()->counters()->update_counters(); | |
| 2382 | |
| 2383 { | |
| 2384 // Clear _foregroundGCShouldWait and, in the event that the | |
| 2385 // foreground collector is waiting, notify it, before | |
| 2386 // returning. | |
| 2387 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
| 2388 _foregroundGCShouldWait = false; | |
| 2389 if (_foregroundGCIsActive) { | |
| 2390 CGC_lock->notify(); | |
| 2391 } | |
| 2392 assert(!ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 2393 "Possible deadlock"); | |
| 2394 } | |
| 2395 if (TraceCMSState) { | |
| 2396 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT | |
| 2397 " exiting collection CMS state %d", | |
| 2398 Thread::current(), _collectorState); | |
| 2399 } | |
| 2400 if (PrintGC && Verbose) { | |
| 2401 _cmsGen->print_heap_change(prev_used); | |
| 2402 } | |
| 2403 } | |
| 2404 | |
| 2405 void CMSCollector::collect_in_foreground(bool clear_all_soft_refs) { | |
| 2406 assert(_foregroundGCIsActive && !_foregroundGCShouldWait, | |
| 2407 "Foreground collector should be waiting, not executing"); | |
| 2408 assert(Thread::current()->is_VM_thread(), "A foreground collection" | |
| 2409 "may only be done by the VM Thread with the world stopped"); | |
| 2410 assert(ConcurrentMarkSweepThread::vm_thread_has_cms_token(), | |
| 2411 "VM thread should have CMS token"); | |
| 2412 | |
| 2413 NOT_PRODUCT(TraceTime t("CMS:MS (foreground) ", PrintGCDetails && Verbose, | |
| 2414 true, gclog_or_tty);) | |
| 2415 if (UseAdaptiveSizePolicy) { | |
| 2416 size_policy()->ms_collection_begin(); | |
| 2417 } | |
| 2418 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact); | |
| 2419 | |
| 2420 HandleMark hm; // Discard invalid handles created during verification | |
| 2421 | |
| 2422 if (VerifyBeforeGC && | |
| 2423 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
|
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2424 Universe::verify(); |
| 0 | 2425 } |
| 2426 | |
|
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2427 // Snapshot the soft reference policy to be used in this collection cycle. |
|
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2428 ref_processor()->setup_policy(clear_all_soft_refs); |
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2429 |
| 0 | 2430 bool init_mark_was_synchronous = false; // until proven otherwise |
| 2431 while (_collectorState != Idling) { | |
| 2432 if (TraceCMSState) { | |
| 2433 gclog_or_tty->print_cr("Thread " INTPTR_FORMAT " in CMS state %d", | |
| 2434 Thread::current(), _collectorState); | |
| 2435 } | |
| 2436 switch (_collectorState) { | |
| 2437 case InitialMarking: | |
| 2438 init_mark_was_synchronous = true; // fact to be exploited in re-mark | |
| 2439 checkpointRootsInitial(false); | |
| 2440 assert(_collectorState == Marking, "Collector state should have changed" | |
| 2441 " within checkpointRootsInitial()"); | |
| 2442 break; | |
| 2443 case Marking: | |
| 2444 // initial marking in checkpointRootsInitialWork has been completed | |
| 2445 if (VerifyDuringGC && | |
| 2446 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
| 2447 gclog_or_tty->print("Verify before initial mark: "); | |
|
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|
2448 Universe::verify(); |
| 0 | 2449 } |
| 2450 { | |
| 2451 bool res = markFromRoots(false); | |
| 2452 assert(res && _collectorState == FinalMarking, "Collector state should " | |
| 2453 "have changed"); | |
| 2454 break; | |
| 2455 } | |
| 2456 case FinalMarking: | |
| 2457 if (VerifyDuringGC && | |
| 2458 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
| 2459 gclog_or_tty->print("Verify before re-mark: "); | |
|
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|
2460 Universe::verify(); |
| 0 | 2461 } |
| 2462 checkpointRootsFinal(false, clear_all_soft_refs, | |
| 2463 init_mark_was_synchronous); | |
| 2464 assert(_collectorState == Sweeping, "Collector state should not " | |
| 2465 "have changed within checkpointRootsFinal()"); | |
| 2466 break; | |
| 2467 case Sweeping: | |
| 2468 // final marking in checkpointRootsFinal has been completed | |
| 2469 if (VerifyDuringGC && | |
| 2470 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
| 2471 gclog_or_tty->print("Verify before sweep: "); | |
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|
2472 Universe::verify(); |
| 0 | 2473 } |
| 2474 sweep(false); | |
| 2475 assert(_collectorState == Resizing, "Incorrect state"); | |
| 2476 break; | |
| 2477 case Resizing: { | |
| 2478 // Sweeping has been completed; the actual resize in this case | |
| 2479 // is done separately; nothing to be done in this state. | |
| 2480 _collectorState = Resetting; | |
| 2481 break; | |
| 2482 } | |
| 2483 case Resetting: | |
| 2484 // The heap has been resized. | |
| 2485 if (VerifyDuringGC && | |
| 2486 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
| 2487 gclog_or_tty->print("Verify before reset: "); | |
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2488 Universe::verify(); |
| 0 | 2489 } |
| 2490 reset(false); | |
| 2491 assert(_collectorState == Idling, "Collector state should " | |
| 2492 "have changed"); | |
| 2493 break; | |
| 2494 case Precleaning: | |
| 2495 case AbortablePreclean: | |
| 2496 // Elide the preclean phase | |
| 2497 _collectorState = FinalMarking; | |
| 2498 break; | |
| 2499 default: | |
| 2500 ShouldNotReachHere(); | |
| 2501 } | |
| 2502 if (TraceCMSState) { | |
| 2503 gclog_or_tty->print_cr(" Thread " INTPTR_FORMAT " done - next CMS state %d", | |
| 2504 Thread::current(), _collectorState); | |
| 2505 } | |
| 2506 } | |
| 2507 | |
| 2508 if (UseAdaptiveSizePolicy) { | |
| 2509 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 2510 size_policy()->ms_collection_end(gch->gc_cause()); | |
| 2511 } | |
| 2512 | |
| 2513 if (VerifyAfterGC && | |
| 2514 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
|
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2515 Universe::verify(); |
| 0 | 2516 } |
| 2517 if (TraceCMSState) { | |
| 2518 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT | |
| 2519 " exiting collection CMS state %d", | |
| 2520 Thread::current(), _collectorState); | |
| 2521 } | |
| 2522 } | |
| 2523 | |
| 2524 bool CMSCollector::waitForForegroundGC() { | |
| 2525 bool res = false; | |
| 2526 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 2527 "CMS thread should have CMS token"); | |
| 2528 // Block the foreground collector until the | |
| 2529 // background collectors decides whether to | |
| 2530 // yield. | |
| 2531 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
| 2532 _foregroundGCShouldWait = true; | |
| 2533 if (_foregroundGCIsActive) { | |
| 2534 // The background collector yields to the | |
| 2535 // foreground collector and returns a value | |
| 2536 // indicating that it has yielded. The foreground | |
| 2537 // collector can proceed. | |
| 2538 res = true; | |
| 2539 _foregroundGCShouldWait = false; | |
| 2540 ConcurrentMarkSweepThread::clear_CMS_flag( | |
| 2541 ConcurrentMarkSweepThread::CMS_cms_has_token); | |
| 2542 ConcurrentMarkSweepThread::set_CMS_flag( | |
| 2543 ConcurrentMarkSweepThread::CMS_cms_wants_token); | |
| 2544 // Get a possibly blocked foreground thread going | |
| 2545 CGC_lock->notify(); | |
| 2546 if (TraceCMSState) { | |
| 2547 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT " waiting at CMS state %d", | |
| 2548 Thread::current(), _collectorState); | |
| 2549 } | |
| 2550 while (_foregroundGCIsActive) { | |
| 2551 CGC_lock->wait(Mutex::_no_safepoint_check_flag); | |
| 2552 } | |
| 2553 ConcurrentMarkSweepThread::set_CMS_flag( | |
| 2554 ConcurrentMarkSweepThread::CMS_cms_has_token); | |
| 2555 ConcurrentMarkSweepThread::clear_CMS_flag( | |
| 2556 ConcurrentMarkSweepThread::CMS_cms_wants_token); | |
| 2557 } | |
| 2558 if (TraceCMSState) { | |
| 2559 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT " continuing at CMS state %d", | |
| 2560 Thread::current(), _collectorState); | |
| 2561 } | |
| 2562 return res; | |
| 2563 } | |
| 2564 | |
| 2565 // Because of the need to lock the free lists and other structures in | |
| 2566 // the collector, common to all the generations that the collector is | |
| 2567 // collecting, we need the gc_prologues of individual CMS generations | |
| 2568 // delegate to their collector. It may have been simpler had the | |
| 2569 // current infrastructure allowed one to call a prologue on a | |
| 2570 // collector. In the absence of that we have the generation's | |
| 2571 // prologue delegate to the collector, which delegates back | |
| 2572 // some "local" work to a worker method in the individual generations | |
| 2573 // that it's responsible for collecting, while itself doing any | |
| 2574 // work common to all generations it's responsible for. A similar | |
| 2575 // comment applies to the gc_epilogue()'s. | |
| 2576 // The role of the varaible _between_prologue_and_epilogue is to | |
| 2577 // enforce the invocation protocol. | |
| 2578 void CMSCollector::gc_prologue(bool full) { | |
|
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2579 // Call gc_prologue_work() for the CMSGen |
| 0 | 2580 // we are responsible for. |
| 2581 | |
| 2582 // The following locking discipline assumes that we are only called | |
| 2583 // when the world is stopped. | |
| 2584 assert(SafepointSynchronize::is_at_safepoint(), "world is stopped assumption"); | |
| 2585 | |
| 2586 // The CMSCollector prologue must call the gc_prologues for the | |
|
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2587 // "generations" that it's responsible |
| 0 | 2588 // for. |
| 2589 | |
| 2590 assert( Thread::current()->is_VM_thread() | |
| 2591 || ( CMSScavengeBeforeRemark | |
| 2592 && Thread::current()->is_ConcurrentGC_thread()), | |
| 2593 "Incorrect thread type for prologue execution"); | |
| 2594 | |
| 2595 if (_between_prologue_and_epilogue) { | |
| 2596 // We have already been invoked; this is a gc_prologue delegation | |
| 2597 // from yet another CMS generation that we are responsible for, just | |
| 2598 // ignore it since all relevant work has already been done. | |
| 2599 return; | |
| 2600 } | |
| 2601 | |
| 2602 // set a bit saying prologue has been called; cleared in epilogue | |
| 2603 _between_prologue_and_epilogue = true; | |
| 2604 // Claim locks for common data structures, then call gc_prologue_work() | |
|
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2605 // for each CMSGen. |
| 0 | 2606 |
| 2607 getFreelistLocks(); // gets free list locks on constituent spaces | |
| 2608 bitMapLock()->lock_without_safepoint_check(); | |
| 2609 | |
| 2610 // Should call gc_prologue_work() for all cms gens we are responsible for | |
|
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2611 bool duringMarking = _collectorState >= Marking |
| 0 | 2612 && _collectorState < Sweeping; |
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2613 |
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2614 // The young collections clear the modified oops state, which tells if |
|
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2615 // there are any modified oops in the class. The remark phase also needs |
|
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2616 // that information. Tell the young collection to save the union of all |
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2617 // modified klasses. |
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2618 if (duringMarking) { |
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2619 _ct->klass_rem_set()->set_accumulate_modified_oops(true); |
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2620 } |
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2621 |
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2622 bool registerClosure = duringMarking; |
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2623 |
|
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2624 ModUnionClosure* muc = CollectedHeap::use_parallel_gc_threads() ? |
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2625 &_modUnionClosurePar |
| 0 | 2626 : &_modUnionClosure; |
| 2627 _cmsGen->gc_prologue_work(full, registerClosure, muc); | |
| 2628 | |
| 2629 if (!full) { | |
| 2630 stats().record_gc0_begin(); | |
| 2631 } | |
| 2632 } | |
| 2633 | |
| 2634 void ConcurrentMarkSweepGeneration::gc_prologue(bool full) { | |
|
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2635 |
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2636 _capacity_at_prologue = capacity(); |
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2637 _used_at_prologue = used(); |
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2638 |
| 0 | 2639 // Delegate to CMScollector which knows how to coordinate between |
| 2640 // this and any other CMS generations that it is responsible for | |
| 2641 // collecting. | |
| 2642 collector()->gc_prologue(full); | |
| 2643 } | |
| 2644 | |
| 2645 // This is a "private" interface for use by this generation's CMSCollector. | |
| 2646 // Not to be called directly by any other entity (for instance, | |
| 2647 // GenCollectedHeap, which calls the "public" gc_prologue method above). | |
| 2648 void ConcurrentMarkSweepGeneration::gc_prologue_work(bool full, | |
| 2649 bool registerClosure, ModUnionClosure* modUnionClosure) { | |
| 2650 assert(!incremental_collection_failed(), "Shouldn't be set yet"); | |
| 2651 assert(cmsSpace()->preconsumptionDirtyCardClosure() == NULL, | |
| 2652 "Should be NULL"); | |
| 2653 if (registerClosure) { | |
| 2654 cmsSpace()->setPreconsumptionDirtyCardClosure(modUnionClosure); | |
| 2655 } | |
| 2656 cmsSpace()->gc_prologue(); | |
| 2657 // Clear stat counters | |
| 2658 NOT_PRODUCT( | |
| 2659 assert(_numObjectsPromoted == 0, "check"); | |
| 2660 assert(_numWordsPromoted == 0, "check"); | |
| 2661 if (Verbose && PrintGC) { | |
| 2662 gclog_or_tty->print("Allocated "SIZE_FORMAT" objects, " | |
| 2663 SIZE_FORMAT" bytes concurrently", | |
| 2664 _numObjectsAllocated, _numWordsAllocated*sizeof(HeapWord)); | |
| 2665 } | |
| 2666 _numObjectsAllocated = 0; | |
| 2667 _numWordsAllocated = 0; | |
| 2668 ) | |
| 2669 } | |
| 2670 | |
| 2671 void CMSCollector::gc_epilogue(bool full) { | |
| 2672 // The following locking discipline assumes that we are only called | |
| 2673 // when the world is stopped. | |
| 2674 assert(SafepointSynchronize::is_at_safepoint(), | |
| 2675 "world is stopped assumption"); | |
| 2676 | |
| 2677 // Currently the CMS epilogue (see CompactibleFreeListSpace) merely checks | |
| 2678 // if linear allocation blocks need to be appropriately marked to allow the | |
| 2679 // the blocks to be parsable. We also check here whether we need to nudge the | |
| 2680 // CMS collector thread to start a new cycle (if it's not already active). | |
| 2681 assert( Thread::current()->is_VM_thread() | |
| 2682 || ( CMSScavengeBeforeRemark | |
| 2683 && Thread::current()->is_ConcurrentGC_thread()), | |
| 2684 "Incorrect thread type for epilogue execution"); | |
| 2685 | |
| 2686 if (!_between_prologue_and_epilogue) { | |
| 2687 // We have already been invoked; this is a gc_epilogue delegation | |
| 2688 // from yet another CMS generation that we are responsible for, just | |
| 2689 // ignore it since all relevant work has already been done. | |
| 2690 return; | |
| 2691 } | |
| 2692 assert(haveFreelistLocks(), "must have freelist locks"); | |
| 2693 assert_lock_strong(bitMapLock()); | |
| 2694 | |
|
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2695 _ct->klass_rem_set()->set_accumulate_modified_oops(false); |
|
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2696 |
| 0 | 2697 _cmsGen->gc_epilogue_work(full); |
| 2698 | |
| 2699 if (_collectorState == AbortablePreclean || _collectorState == Precleaning) { | |
| 2700 // in case sampling was not already enabled, enable it | |
| 2701 _start_sampling = true; | |
| 2702 } | |
| 2703 // reset _eden_chunk_array so sampling starts afresh | |
| 2704 _eden_chunk_index = 0; | |
| 2705 | |
| 2706 size_t cms_used = _cmsGen->cmsSpace()->used(); | |
| 2707 | |
| 2708 // update performance counters - this uses a special version of | |
| 2709 // update_counters() that allows the utilization to be passed as a | |
| 2710 // parameter, avoiding multiple calls to used(). | |
| 2711 // | |
| 2712 _cmsGen->update_counters(cms_used); | |
| 2713 | |
| 2714 if (CMSIncrementalMode) { | |
| 2715 icms_update_allocation_limits(); | |
| 2716 } | |
| 2717 | |
| 2718 bitMapLock()->unlock(); | |
| 2719 releaseFreelistLocks(); | |
| 2720 | |
|
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2721 if (!CleanChunkPoolAsync) { |
|
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2722 Chunk::clean_chunk_pool(); |
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2723 } |
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2724 |
| 0 | 2725 _between_prologue_and_epilogue = false; // ready for next cycle |
| 2726 } | |
| 2727 | |
| 2728 void ConcurrentMarkSweepGeneration::gc_epilogue(bool full) { | |
| 2729 collector()->gc_epilogue(full); | |
| 2730 | |
| 2731 // Also reset promotion tracking in par gc thread states. | |
|
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2732 if (CollectedHeap::use_parallel_gc_threads()) { |
| 0 | 2733 for (uint i = 0; i < ParallelGCThreads; i++) { |
|
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2734 _par_gc_thread_states[i]->promo.stopTrackingPromotions(i); |
| 0 | 2735 } |
| 2736 } | |
| 2737 } | |
| 2738 | |
| 2739 void ConcurrentMarkSweepGeneration::gc_epilogue_work(bool full) { | |
| 2740 assert(!incremental_collection_failed(), "Should have been cleared"); | |
| 2741 cmsSpace()->setPreconsumptionDirtyCardClosure(NULL); | |
| 2742 cmsSpace()->gc_epilogue(); | |
| 2743 // Print stat counters | |
| 2744 NOT_PRODUCT( | |
| 2745 assert(_numObjectsAllocated == 0, "check"); | |
| 2746 assert(_numWordsAllocated == 0, "check"); | |
| 2747 if (Verbose && PrintGC) { | |
| 2748 gclog_or_tty->print("Promoted "SIZE_FORMAT" objects, " | |
| 2749 SIZE_FORMAT" bytes", | |
| 2750 _numObjectsPromoted, _numWordsPromoted*sizeof(HeapWord)); | |
| 2751 } | |
| 2752 _numObjectsPromoted = 0; | |
| 2753 _numWordsPromoted = 0; | |
| 2754 ) | |
| 2755 | |
| 2756 if (PrintGC && Verbose) { | |
| 2757 // Call down the chain in contiguous_available needs the freelistLock | |
| 2758 // so print this out before releasing the freeListLock. | |
| 2759 gclog_or_tty->print(" Contiguous available "SIZE_FORMAT" bytes ", | |
| 2760 contiguous_available()); | |
| 2761 } | |
| 2762 } | |
| 2763 | |
| 2764 #ifndef PRODUCT | |
| 2765 bool CMSCollector::have_cms_token() { | |
| 2766 Thread* thr = Thread::current(); | |
| 2767 if (thr->is_VM_thread()) { | |
| 2768 return ConcurrentMarkSweepThread::vm_thread_has_cms_token(); | |
| 2769 } else if (thr->is_ConcurrentGC_thread()) { | |
| 2770 return ConcurrentMarkSweepThread::cms_thread_has_cms_token(); | |
| 2771 } else if (thr->is_GC_task_thread()) { | |
| 2772 return ConcurrentMarkSweepThread::vm_thread_has_cms_token() && | |
| 2773 ParGCRareEvent_lock->owned_by_self(); | |
| 2774 } | |
| 2775 return false; | |
| 2776 } | |
| 2777 #endif | |
| 2778 | |
| 2779 // Check reachability of the given heap address in CMS generation, | |
| 2780 // treating all other generations as roots. | |
| 2781 bool CMSCollector::is_cms_reachable(HeapWord* addr) { | |
| 2782 // We could "guarantee" below, rather than assert, but i'll | |
| 2783 // leave these as "asserts" so that an adventurous debugger | |
| 2784 // could try this in the product build provided some subset of | |
| 2785 // the conditions were met, provided they were intersted in the | |
| 2786 // results and knew that the computation below wouldn't interfere | |
| 2787 // with other concurrent computations mutating the structures | |
| 2788 // being read or written. | |
| 2789 assert(SafepointSynchronize::is_at_safepoint(), | |
| 2790 "Else mutations in object graph will make answer suspect"); | |
| 2791 assert(have_cms_token(), "Should hold cms token"); | |
| 2792 assert(haveFreelistLocks(), "must hold free list locks"); | |
| 2793 assert_lock_strong(bitMapLock()); | |
| 2794 | |
| 2795 // Clear the marking bit map array before starting, but, just | |
| 2796 // for kicks, first report if the given address is already marked | |
| 2797 gclog_or_tty->print_cr("Start: Address 0x%x is%s marked", addr, | |
| 2798 _markBitMap.isMarked(addr) ? "" : " not"); | |
| 2799 | |
| 2800 if (verify_after_remark()) { | |
| 2801 MutexLockerEx x(verification_mark_bm()->lock(), Mutex::_no_safepoint_check_flag); | |
| 2802 bool result = verification_mark_bm()->isMarked(addr); | |
| 2803 gclog_or_tty->print_cr("TransitiveMark: Address 0x%x %s marked", addr, | |
| 2804 result ? "IS" : "is NOT"); | |
| 2805 return result; | |
| 2806 } else { | |
| 2807 gclog_or_tty->print_cr("Could not compute result"); | |
| 2808 return false; | |
| 2809 } | |
| 2810 } | |
| 2811 | |
|
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2812 |
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2813 void |
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2814 CMSCollector::print_on_error(outputStream* st) { |
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2815 CMSCollector* collector = ConcurrentMarkSweepGeneration::_collector; |
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2816 if (collector != NULL) { |
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2817 CMSBitMap* bitmap = &collector->_markBitMap; |
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2818 st->print_cr("Marking Bits: (CMSBitMap*) " PTR_FORMAT, bitmap); |
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2819 bitmap->print_on_error(st, " Bits: "); |
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2820 |
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|
2821 st->cr(); |
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2822 |
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2823 CMSBitMap* mut_bitmap = &collector->_modUnionTable; |
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2824 st->print_cr("Mod Union Table: (CMSBitMap*) " PTR_FORMAT, mut_bitmap); |
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2825 mut_bitmap->print_on_error(st, " Bits: "); |
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2826 } |
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2827 } |
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2828 |
| 0 | 2829 //////////////////////////////////////////////////////// |
| 2830 // CMS Verification Support | |
| 2831 //////////////////////////////////////////////////////// | |
| 2832 // Following the remark phase, the following invariant | |
| 2833 // should hold -- each object in the CMS heap which is | |
| 2834 // marked in markBitMap() should be marked in the verification_mark_bm(). | |
| 2835 | |
| 2836 class VerifyMarkedClosure: public BitMapClosure { | |
| 2837 CMSBitMap* _marks; | |
| 2838 bool _failed; | |
| 2839 | |
| 2840 public: | |
| 2841 VerifyMarkedClosure(CMSBitMap* bm): _marks(bm), _failed(false) {} | |
| 2842 | |
|
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2843 bool do_bit(size_t offset) { |
| 0 | 2844 HeapWord* addr = _marks->offsetToHeapWord(offset); |
| 2845 if (!_marks->isMarked(addr)) { | |
|
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2846 oop(addr)->print_on(gclog_or_tty); |
| 0 | 2847 gclog_or_tty->print_cr(" ("INTPTR_FORMAT" should have been marked)", addr); |
| 2848 _failed = true; | |
| 2849 } | |
|
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2850 return true; |
| 0 | 2851 } |
| 2852 | |
| 2853 bool failed() { return _failed; } | |
| 2854 }; | |
| 2855 | |
| 2856 bool CMSCollector::verify_after_remark() { | |
| 2857 gclog_or_tty->print(" [Verifying CMS Marking... "); | |
| 2858 MutexLockerEx ml(verification_mark_bm()->lock(), Mutex::_no_safepoint_check_flag); | |
| 2859 static bool init = false; | |
| 2860 | |
| 2861 assert(SafepointSynchronize::is_at_safepoint(), | |
| 2862 "Else mutations in object graph will make answer suspect"); | |
| 2863 assert(have_cms_token(), | |
| 2864 "Else there may be mutual interference in use of " | |
| 2865 " verification data structures"); | |
| 2866 assert(_collectorState > Marking && _collectorState <= Sweeping, | |
| 2867 "Else marking info checked here may be obsolete"); | |
| 2868 assert(haveFreelistLocks(), "must hold free list locks"); | |
| 2869 assert_lock_strong(bitMapLock()); | |
| 2870 | |
| 2871 | |
| 2872 // Allocate marking bit map if not already allocated | |
| 2873 if (!init) { // first time | |
| 2874 if (!verification_mark_bm()->allocate(_span)) { | |
| 2875 return false; | |
| 2876 } | |
| 2877 init = true; | |
| 2878 } | |
| 2879 | |
| 2880 assert(verification_mark_stack()->isEmpty(), "Should be empty"); | |
| 2881 | |
| 2882 // Turn off refs discovery -- so we will be tracing through refs. | |
| 2883 // This is as intended, because by this time | |
| 2884 // GC must already have cleared any refs that need to be cleared, | |
| 2885 // and traced those that need to be marked; moreover, | |
| 2886 // the marking done here is not going to intefere in any | |
| 2887 // way with the marking information used by GC. | |
| 2888 NoRefDiscovery no_discovery(ref_processor()); | |
| 2889 | |
| 2890 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact;) | |
| 2891 | |
| 2892 // Clear any marks from a previous round | |
| 2893 verification_mark_bm()->clear_all(); | |
| 2894 assert(verification_mark_stack()->isEmpty(), "markStack should be empty"); | |
|
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2895 verify_work_stacks_empty(); |
| 0 | 2896 |
| 2897 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 2898 gch->ensure_parsability(false); // fill TLABs, but no need to retire them | |
| 2899 // Update the saved marks which may affect the root scans. | |
| 2900 gch->save_marks(); | |
| 2901 | |
| 2902 if (CMSRemarkVerifyVariant == 1) { | |
| 2903 // In this first variant of verification, we complete | |
| 2904 // all marking, then check if the new marks-verctor is | |
| 2905 // a subset of the CMS marks-vector. | |
| 2906 verify_after_remark_work_1(); | |
| 2907 } else if (CMSRemarkVerifyVariant == 2) { | |
| 2908 // In this second variant of verification, we flag an error | |
| 2909 // (i.e. an object reachable in the new marks-vector not reachable | |
| 2910 // in the CMS marks-vector) immediately, also indicating the | |
| 2911 // identify of an object (A) that references the unmarked object (B) -- | |
| 2912 // presumably, a mutation to A failed to be picked up by preclean/remark? | |
| 2913 verify_after_remark_work_2(); | |
| 2914 } else { | |
| 2915 warning("Unrecognized value %d for CMSRemarkVerifyVariant", | |
| 2916 CMSRemarkVerifyVariant); | |
| 2917 } | |
| 2918 gclog_or_tty->print(" done] "); | |
| 2919 return true; | |
| 2920 } | |
| 2921 | |
| 2922 void CMSCollector::verify_after_remark_work_1() { | |
| 2923 ResourceMark rm; | |
| 2924 HandleMark hm; | |
| 2925 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 2926 | |
|
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2927 // Get a clear set of claim bits for the strong roots processing to work with. |
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2928 ClassLoaderDataGraph::clear_claimed_marks(); |
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2929 |
| 0 | 2930 // Mark from roots one level into CMS |
|
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2931 MarkRefsIntoClosure notOlder(_span, verification_mark_bm()); |
| 0 | 2932 gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel. |
| 2933 | |
| 2934 gch->gen_process_strong_roots(_cmsGen->level(), | |
| 2935 true, // younger gens are roots | |
|
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|
2936 true, // activate StrongRootsScope |
|
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2937 false, // not scavenging |
| 0 | 2938 SharedHeap::ScanningOption(roots_scanning_options()), |
|
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2939 ¬Older, |
|
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2940 true, // walk code active on stacks |
|
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2941 NULL, |
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|
2942 NULL); // SSS: Provide correct closure |
| 0 | 2943 |
| 2944 // Now mark from the roots | |
| 2945 MarkFromRootsClosure markFromRootsClosure(this, _span, | |
|
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2946 verification_mark_bm(), verification_mark_stack(), |
| 0 | 2947 false /* don't yield */, true /* verifying */); |
| 2948 assert(_restart_addr == NULL, "Expected pre-condition"); | |
| 2949 verification_mark_bm()->iterate(&markFromRootsClosure); | |
| 2950 while (_restart_addr != NULL) { | |
| 2951 // Deal with stack overflow: by restarting at the indicated | |
| 2952 // address. | |
| 2953 HeapWord* ra = _restart_addr; | |
| 2954 markFromRootsClosure.reset(ra); | |
| 2955 _restart_addr = NULL; | |
| 2956 verification_mark_bm()->iterate(&markFromRootsClosure, ra, _span.end()); | |
| 2957 } | |
| 2958 assert(verification_mark_stack()->isEmpty(), "Should have been drained"); | |
| 2959 verify_work_stacks_empty(); | |
| 2960 | |
| 2961 // Marking completed -- now verify that each bit marked in | |
| 2962 // verification_mark_bm() is also marked in markBitMap(); flag all | |
| 2963 // errors by printing corresponding objects. | |
| 2964 VerifyMarkedClosure vcl(markBitMap()); | |
| 2965 verification_mark_bm()->iterate(&vcl); | |
| 2966 if (vcl.failed()) { | |
| 2967 gclog_or_tty->print("Verification failed"); | |
|
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2968 Universe::heap()->print_on(gclog_or_tty); |
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2969 fatal("CMS: failed marking verification after remark"); |
| 0 | 2970 } |
| 2971 } | |
| 2972 | |
|
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2973 class VerifyKlassOopsKlassClosure : public KlassClosure { |
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2974 class VerifyKlassOopsClosure : public OopClosure { |
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2975 CMSBitMap* _bitmap; |
|
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2976 public: |
|
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2977 VerifyKlassOopsClosure(CMSBitMap* bitmap) : _bitmap(bitmap) { } |
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2978 void do_oop(oop* p) { guarantee(*p == NULL || _bitmap->isMarked((HeapWord*) *p), "Should be marked"); } |
|
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2979 void do_oop(narrowOop* p) { ShouldNotReachHere(); } |
|
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2980 } _oop_closure; |
|
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2981 public: |
|
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2982 VerifyKlassOopsKlassClosure(CMSBitMap* bitmap) : _oop_closure(bitmap) {} |
|
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2983 void do_klass(Klass* k) { |
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2984 k->oops_do(&_oop_closure); |
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2985 } |
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2986 }; |
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2987 |
| 0 | 2988 void CMSCollector::verify_after_remark_work_2() { |
| 2989 ResourceMark rm; | |
| 2990 HandleMark hm; | |
| 2991 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 2992 | |
|
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2993 // Get a clear set of claim bits for the strong roots processing to work with. |
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2994 ClassLoaderDataGraph::clear_claimed_marks(); |
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2995 |
| 0 | 2996 // Mark from roots one level into CMS |
| 2997 MarkRefsIntoVerifyClosure notOlder(_span, verification_mark_bm(), | |
|
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2998 markBitMap()); |
|
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2999 CMKlassClosure klass_closure(¬Older); |
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3000 |
| 0 | 3001 gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel. |
| 3002 gch->gen_process_strong_roots(_cmsGen->level(), | |
| 3003 true, // younger gens are roots | |
|
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3004 true, // activate StrongRootsScope |
|
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3005 false, // not scavenging |
| 0 | 3006 SharedHeap::ScanningOption(roots_scanning_options()), |
|
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3007 ¬Older, |
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3008 true, // walk code active on stacks |
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3009 NULL, |
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|
3010 &klass_closure); |
| 0 | 3011 |
| 3012 // Now mark from the roots | |
| 3013 MarkFromRootsVerifyClosure markFromRootsClosure(this, _span, | |
| 3014 verification_mark_bm(), markBitMap(), verification_mark_stack()); | |
| 3015 assert(_restart_addr == NULL, "Expected pre-condition"); | |
| 3016 verification_mark_bm()->iterate(&markFromRootsClosure); | |
| 3017 while (_restart_addr != NULL) { | |
| 3018 // Deal with stack overflow: by restarting at the indicated | |
| 3019 // address. | |
| 3020 HeapWord* ra = _restart_addr; | |
| 3021 markFromRootsClosure.reset(ra); | |
| 3022 _restart_addr = NULL; | |
| 3023 verification_mark_bm()->iterate(&markFromRootsClosure, ra, _span.end()); | |
| 3024 } | |
| 3025 assert(verification_mark_stack()->isEmpty(), "Should have been drained"); | |
| 3026 verify_work_stacks_empty(); | |
|
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3027 |
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3028 VerifyKlassOopsKlassClosure verify_klass_oops(verification_mark_bm()); |
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3029 ClassLoaderDataGraph::classes_do(&verify_klass_oops); |
| 0 | 3030 |
| 3031 // Marking completed -- now verify that each bit marked in | |
| 3032 // verification_mark_bm() is also marked in markBitMap(); flag all | |
| 3033 // errors by printing corresponding objects. | |
| 3034 VerifyMarkedClosure vcl(markBitMap()); | |
| 3035 verification_mark_bm()->iterate(&vcl); | |
| 3036 assert(!vcl.failed(), "Else verification above should not have succeeded"); | |
| 3037 } | |
| 3038 | |
| 3039 void ConcurrentMarkSweepGeneration::save_marks() { | |
| 3040 // delegate to CMS space | |
| 3041 cmsSpace()->save_marks(); | |
| 3042 for (uint i = 0; i < ParallelGCThreads; i++) { | |
| 3043 _par_gc_thread_states[i]->promo.startTrackingPromotions(); | |
| 3044 } | |
| 3045 } | |
| 3046 | |
| 3047 bool ConcurrentMarkSweepGeneration::no_allocs_since_save_marks() { | |
| 3048 return cmsSpace()->no_allocs_since_save_marks(); | |
| 3049 } | |
| 3050 | |
| 3051 #define CMS_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \ | |
| 3052 \ | |
| 3053 void ConcurrentMarkSweepGeneration:: \ | |
| 3054 oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) { \ | |
| 3055 cl->set_generation(this); \ | |
| 3056 cmsSpace()->oop_since_save_marks_iterate##nv_suffix(cl); \ | |
| 3057 cl->reset_generation(); \ | |
| 3058 save_marks(); \ | |
| 3059 } | |
| 3060 | |
| 3061 ALL_SINCE_SAVE_MARKS_CLOSURES(CMS_SINCE_SAVE_MARKS_DEFN) | |
| 3062 | |
| 3063 void | |
| 3064 ConcurrentMarkSweepGeneration::object_iterate_since_last_GC(ObjectClosure* blk) | |
| 3065 { | |
| 3066 // Not currently implemented; need to do the following. -- ysr. | |
| 3067 // dld -- I think that is used for some sort of allocation profiler. So it | |
| 3068 // really means the objects allocated by the mutator since the last | |
| 3069 // GC. We could potentially implement this cheaply by recording only | |
| 3070 // the direct allocations in a side data structure. | |
| 3071 // | |
| 3072 // I think we probably ought not to be required to support these | |
| 3073 // iterations at any arbitrary point; I think there ought to be some | |
| 3074 // call to enable/disable allocation profiling in a generation/space, | |
| 3075 // and the iterator ought to return the objects allocated in the | |
| 3076 // gen/space since the enable call, or the last iterator call (which | |
| 3077 // will probably be at a GC.) That way, for gens like CM&S that would | |
| 3078 // require some extra data structure to support this, we only pay the | |
| 3079 // cost when it's in use... | |
| 3080 cmsSpace()->object_iterate_since_last_GC(blk); | |
| 3081 } | |
| 3082 | |
| 3083 void | |
| 3084 ConcurrentMarkSweepGeneration::younger_refs_iterate(OopsInGenClosure* cl) { | |
| 3085 cl->set_generation(this); | |
| 3086 younger_refs_in_space_iterate(_cmsSpace, cl); | |
| 3087 cl->reset_generation(); | |
| 3088 } | |
| 3089 | |
| 3090 void | |
|
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3091 ConcurrentMarkSweepGeneration::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) { |
| 0 | 3092 if (freelistLock()->owned_by_self()) { |
| 3093 Generation::oop_iterate(mr, cl); | |
| 3094 } else { | |
| 3095 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 3096 Generation::oop_iterate(mr, cl); | |
| 3097 } | |
| 3098 } | |
| 3099 | |
| 3100 void | |
|
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3101 ConcurrentMarkSweepGeneration::oop_iterate(ExtendedOopClosure* cl) { |
| 0 | 3102 if (freelistLock()->owned_by_self()) { |
| 3103 Generation::oop_iterate(cl); | |
| 3104 } else { | |
| 3105 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 3106 Generation::oop_iterate(cl); | |
| 3107 } | |
| 3108 } | |
| 3109 | |
| 3110 void | |
| 3111 ConcurrentMarkSweepGeneration::object_iterate(ObjectClosure* cl) { | |
| 3112 if (freelistLock()->owned_by_self()) { | |
| 3113 Generation::object_iterate(cl); | |
| 3114 } else { | |
| 3115 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 3116 Generation::object_iterate(cl); | |
| 3117 } | |
| 3118 } | |
| 3119 | |
| 3120 void | |
|
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3121 ConcurrentMarkSweepGeneration::safe_object_iterate(ObjectClosure* cl) { |
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3122 if (freelistLock()->owned_by_self()) { |
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3123 Generation::safe_object_iterate(cl); |
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3124 } else { |
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3125 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); |
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3126 Generation::safe_object_iterate(cl); |
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3127 } |
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3128 } |
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3129 |
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3130 void |
| 0 | 3131 ConcurrentMarkSweepGeneration::post_compact() { |
| 3132 } | |
| 3133 | |
| 3134 void | |
| 3135 ConcurrentMarkSweepGeneration::prepare_for_verify() { | |
| 3136 // Fix the linear allocation blocks to look like free blocks. | |
| 3137 | |
| 3138 // Locks are normally acquired/released in gc_prologue/gc_epilogue, but those | |
| 3139 // are not called when the heap is verified during universe initialization and | |
| 3140 // at vm shutdown. | |
| 3141 if (freelistLock()->owned_by_self()) { | |
| 3142 cmsSpace()->prepare_for_verify(); | |
| 3143 } else { | |
| 3144 MutexLockerEx fll(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 3145 cmsSpace()->prepare_for_verify(); | |
| 3146 } | |
| 3147 } | |
| 3148 | |
| 3149 void | |
| 6008 | 3150 ConcurrentMarkSweepGeneration::verify() { |
| 0 | 3151 // Locks are normally acquired/released in gc_prologue/gc_epilogue, but those |
| 3152 // are not called when the heap is verified during universe initialization and | |
| 3153 // at vm shutdown. | |
| 3154 if (freelistLock()->owned_by_self()) { | |
| 6008 | 3155 cmsSpace()->verify(); |
| 0 | 3156 } else { |
| 3157 MutexLockerEx fll(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 6008 | 3158 cmsSpace()->verify(); |
| 3159 } | |
| 3160 } | |
| 3161 | |
| 3162 void CMSCollector::verify() { | |
| 3163 _cmsGen->verify(); | |
| 0 | 3164 } |
| 3165 | |
| 3166 #ifndef PRODUCT | |
| 3167 bool CMSCollector::overflow_list_is_empty() const { | |
| 3168 assert(_num_par_pushes >= 0, "Inconsistency"); | |
| 3169 if (_overflow_list == NULL) { | |
| 3170 assert(_num_par_pushes == 0, "Inconsistency"); | |
| 3171 } | |
| 3172 return _overflow_list == NULL; | |
| 3173 } | |
| 3174 | |
| 3175 // The methods verify_work_stacks_empty() and verify_overflow_empty() | |
| 3176 // merely consolidate assertion checks that appear to occur together frequently. | |
| 3177 void CMSCollector::verify_work_stacks_empty() const { | |
| 3178 assert(_markStack.isEmpty(), "Marking stack should be empty"); | |
| 3179 assert(overflow_list_is_empty(), "Overflow list should be empty"); | |
| 3180 } | |
| 3181 | |
| 3182 void CMSCollector::verify_overflow_empty() const { | |
| 3183 assert(overflow_list_is_empty(), "Overflow list should be empty"); | |
| 3184 assert(no_preserved_marks(), "No preserved marks"); | |
| 3185 } | |
| 3186 #endif // PRODUCT | |
| 3187 | |
|
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3188 // Decide if we want to enable class unloading as part of the |
|
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3189 // ensuing concurrent GC cycle. We will collect and |
|
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3190 // unload classes if it's the case that: |
|
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|
3191 // (1) an explicit gc request has been made and the flag |
|
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|
3192 // ExplicitGCInvokesConcurrentAndUnloadsClasses is set, OR |
|
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|
3193 // (2) (a) class unloading is enabled at the command line, and |
|
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3194 // (b) old gen is getting really full |
|
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3195 // NOTE: Provided there is no change in the state of the heap between |
|
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|
3196 // calls to this method, it should have idempotent results. Moreover, |
|
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|
3197 // its results should be monotonically increasing (i.e. going from 0 to 1, |
|
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|
3198 // but not 1 to 0) between successive calls between which the heap was |
|
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|
3199 // not collected. For the implementation below, it must thus rely on |
|
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|
3200 // the property that concurrent_cycles_since_last_unload() |
|
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|
3201 // will not decrease unless a collection cycle happened and that |
|
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3202 // _cmsGen->is_too_full() are |
|
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|
3203 // themselves also monotonic in that sense. See check_monotonicity() |
|
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|
3204 // below. |
|
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3205 void CMSCollector::update_should_unload_classes() { |
|
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3206 _should_unload_classes = false; |
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3207 // Condition 1 above |
|
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3208 if (_full_gc_requested && ExplicitGCInvokesConcurrentAndUnloadsClasses) { |
|
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3209 _should_unload_classes = true; |
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|
3210 } else if (CMSClassUnloadingEnabled) { // Condition 2.a above |
|
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3211 // Disjuncts 2.b.(i,ii,iii) above |
|
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3212 _should_unload_classes = (concurrent_cycles_since_last_unload() >= |
|
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|
3213 CMSClassUnloadingMaxInterval) |
|
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3214 || _cmsGen->is_too_full(); |
|
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3215 } |
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3216 } |
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3217 |
|
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3218 bool ConcurrentMarkSweepGeneration::is_too_full() const { |
|
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3219 bool res = should_concurrent_collect(); |
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3220 res = res && (occupancy() > (double)CMSIsTooFullPercentage/100.0); |
|
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3221 return res; |
|
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3222 } |
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3223 |
| 0 | 3224 void CMSCollector::setup_cms_unloading_and_verification_state() { |
|
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3225 const bool should_verify = VerifyBeforeGC || VerifyAfterGC || VerifyDuringGC |
| 0 | 3226 || VerifyBeforeExit; |
|
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|
3227 const int rso = SharedHeap::SO_Strings | SharedHeap::SO_CodeCache; |
| 0 | 3228 |
|
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|
3229 if (should_unload_classes()) { // Should unload classes this cycle |
| 0 | 3230 remove_root_scanning_option(rso); // Shrink the root set appropriately |
| 3231 set_verifying(should_verify); // Set verification state for this cycle | |
| 3232 return; // Nothing else needs to be done at this time | |
| 3233 } | |
| 3234 | |
| 3235 // Not unloading classes this cycle | |
|
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|
3236 assert(!should_unload_classes(), "Inconsitency!"); |
|
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|
3237 if ((!verifying() || unloaded_classes_last_cycle()) && should_verify) { |
| 0 | 3238 // Include symbols, strings and code cache elements to prevent their resurrection. |
| 3239 add_root_scanning_option(rso); | |
| 3240 set_verifying(true); | |
| 3241 } else if (verifying() && !should_verify) { | |
| 3242 // We were verifying, but some verification flags got disabled. | |
| 3243 set_verifying(false); | |
| 3244 // Exclude symbols, strings and code cache elements from root scanning to | |
| 3245 // reduce IM and RM pauses. | |
| 3246 remove_root_scanning_option(rso); | |
| 3247 } | |
| 3248 } | |
| 3249 | |
| 3250 | |
| 3251 #ifndef PRODUCT | |
| 3252 HeapWord* CMSCollector::block_start(const void* p) const { | |
| 3253 const HeapWord* addr = (HeapWord*)p; | |
| 3254 if (_span.contains(p)) { | |
| 3255 if (_cmsGen->cmsSpace()->is_in_reserved(addr)) { | |
| 3256 return _cmsGen->cmsSpace()->block_start(p); | |
| 3257 } | |
| 3258 } | |
| 3259 return NULL; | |
| 3260 } | |
| 3261 #endif | |
| 3262 | |
| 3263 HeapWord* | |
| 3264 ConcurrentMarkSweepGeneration::expand_and_allocate(size_t word_size, | |
| 3265 bool tlab, | |
| 3266 bool parallel) { | |
|
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|
3267 CMSSynchronousYieldRequest yr; |
| 0 | 3268 assert(!tlab, "Can't deal with TLAB allocation"); |
| 3269 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 3270 expand(word_size*HeapWordSize, MinHeapDeltaBytes, | |
| 3271 CMSExpansionCause::_satisfy_allocation); | |
| 3272 if (GCExpandToAllocateDelayMillis > 0) { | |
| 3273 os::sleep(Thread::current(), GCExpandToAllocateDelayMillis, false); | |
| 3274 } | |
|
9
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6642634: Test nsk/regression/b6186200 crashed with SIGSEGV
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|
3275 return have_lock_and_allocate(word_size, tlab); |
| 0 | 3276 } |
| 3277 | |
| 3278 // YSR: All of this generation expansion/shrinking stuff is an exact copy of | |
| 3279 // OneContigSpaceCardGeneration, which makes me wonder if we should move this | |
| 3280 // to CardGeneration and share it... | |
|
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|
3281 bool ConcurrentMarkSweepGeneration::expand(size_t bytes, size_t expand_bytes) { |
|
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|
3282 return CardGeneration::expand(bytes, expand_bytes); |
|
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|
3283 } |
|
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|
3284 |
| 0 | 3285 void ConcurrentMarkSweepGeneration::expand(size_t bytes, size_t expand_bytes, |
| 3286 CMSExpansionCause::Cause cause) | |
| 3287 { | |
|
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|
3288 |
|
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|
3289 bool success = expand(bytes, expand_bytes); |
|
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|
3290 |
| 0 | 3291 // remember why we expanded; this information is used |
| 3292 // by shouldConcurrentCollect() when making decisions on whether to start | |
| 3293 // a new CMS cycle. | |
| 3294 if (success) { | |
| 3295 set_expansion_cause(cause); | |
| 3296 if (PrintGCDetails && Verbose) { | |
| 3297 gclog_or_tty->print_cr("Expanded CMS gen for %s", | |
| 3298 CMSExpansionCause::to_string(cause)); | |
| 3299 } | |
| 3300 } | |
| 3301 } | |
| 3302 | |
| 3303 HeapWord* ConcurrentMarkSweepGeneration::expand_and_par_lab_allocate(CMSParGCThreadState* ps, size_t word_sz) { | |
| 3304 HeapWord* res = NULL; | |
| 3305 MutexLocker x(ParGCRareEvent_lock); | |
| 3306 while (true) { | |
| 3307 // Expansion by some other thread might make alloc OK now: | |
| 3308 res = ps->lab.alloc(word_sz); | |
| 3309 if (res != NULL) return res; | |
| 3310 // If there's not enough expansion space available, give up. | |
| 3311 if (_virtual_space.uncommitted_size() < (word_sz * HeapWordSize)) { | |
| 3312 return NULL; | |
| 3313 } | |
| 3314 // Otherwise, we try expansion. | |
| 3315 expand(word_sz*HeapWordSize, MinHeapDeltaBytes, | |
| 3316 CMSExpansionCause::_allocate_par_lab); | |
| 3317 // Now go around the loop and try alloc again; | |
| 3318 // A competing par_promote might beat us to the expansion space, | |
| 3319 // so we may go around the loop again if promotion fails agaion. | |
| 3320 if (GCExpandToAllocateDelayMillis > 0) { | |
| 3321 os::sleep(Thread::current(), GCExpandToAllocateDelayMillis, false); | |
| 3322 } | |
| 3323 } | |
| 3324 } | |
| 3325 | |
| 3326 | |
| 3327 bool ConcurrentMarkSweepGeneration::expand_and_ensure_spooling_space( | |
| 3328 PromotionInfo* promo) { | |
| 3329 MutexLocker x(ParGCRareEvent_lock); | |
| 3330 size_t refill_size_bytes = promo->refillSize() * HeapWordSize; | |
| 3331 while (true) { | |
| 3332 // Expansion by some other thread might make alloc OK now: | |
| 3333 if (promo->ensure_spooling_space()) { | |
| 3334 assert(promo->has_spooling_space(), | |
| 3335 "Post-condition of successful ensure_spooling_space()"); | |
| 3336 return true; | |
| 3337 } | |
| 3338 // If there's not enough expansion space available, give up. | |
| 3339 if (_virtual_space.uncommitted_size() < refill_size_bytes) { | |
| 3340 return false; | |
| 3341 } | |
| 3342 // Otherwise, we try expansion. | |
| 3343 expand(refill_size_bytes, MinHeapDeltaBytes, | |
| 3344 CMSExpansionCause::_allocate_par_spooling_space); | |
| 3345 // Now go around the loop and try alloc again; | |
| 3346 // A competing allocation might beat us to the expansion space, | |
| 3347 // so we may go around the loop again if allocation fails again. | |
| 3348 if (GCExpandToAllocateDelayMillis > 0) { | |
| 3349 os::sleep(Thread::current(), GCExpandToAllocateDelayMillis, false); | |
| 3350 } | |
| 3351 } | |
| 3352 } | |
| 3353 | |
| 3354 | |
|
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|
3355 void ConcurrentMarkSweepGeneration::shrink_by(size_t bytes) { |
|
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|
3356 assert_locked_or_safepoint(ExpandHeap_lock); |
|
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8008508: CMS does not correctly reduce heap size after a Full GC
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|
3357 // Shrink committed space |
|
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|
3358 _virtual_space.shrink_by(bytes); |
|
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8008508: CMS does not correctly reduce heap size after a Full GC
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|
3359 // Shrink space; this also shrinks the space's BOT |
|
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diff
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|
3360 _cmsSpace->set_end((HeapWord*) _virtual_space.high()); |
|
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diff
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|
3361 size_t new_word_size = heap_word_size(_cmsSpace->capacity()); |
|
8617e38bb4cb
8008508: CMS does not correctly reduce heap size after a Full GC
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diff
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|
3362 // Shrink the shared block offset array |
|
8617e38bb4cb
8008508: CMS does not correctly reduce heap size after a Full GC
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diff
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|
3363 _bts->resize(new_word_size); |
|
8617e38bb4cb
8008508: CMS does not correctly reduce heap size after a Full GC
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8784
diff
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|
3364 MemRegion mr(_cmsSpace->bottom(), new_word_size); |
|
8617e38bb4cb
8008508: CMS does not correctly reduce heap size after a Full GC
jmasa
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diff
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|
3365 // Shrink the card table |
|
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diff
changeset
|
3366 Universe::heap()->barrier_set()->resize_covered_region(mr); |
|
8617e38bb4cb
8008508: CMS does not correctly reduce heap size after a Full GC
jmasa
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diff
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|
3367 |
|
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8008508: CMS does not correctly reduce heap size after a Full GC
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|
3368 if (Verbose && PrintGC) { |
|
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8008508: CMS does not correctly reduce heap size after a Full GC
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8784
diff
changeset
|
3369 size_t new_mem_size = _virtual_space.committed_size(); |
|
8617e38bb4cb
8008508: CMS does not correctly reduce heap size after a Full GC
jmasa
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8784
diff
changeset
|
3370 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
|
3371 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
|
3372 name(), old_mem_size/K, new_mem_size/K); |
|
8617e38bb4cb
8008508: CMS does not correctly reduce heap size after a Full GC
jmasa
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diff
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|
3373 } |
|
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diff
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|
3374 } |
| 0 | 3375 |
| 3376 void ConcurrentMarkSweepGeneration::shrink(size_t bytes) { | |
| 3377 assert_locked_or_safepoint(Heap_lock); | |
| 3378 size_t size = ReservedSpace::page_align_size_down(bytes); | |
| 3379 if (size > 0) { | |
| 3380 shrink_by(size); | |
| 3381 } | |
| 3382 } | |
| 3383 | |
| 3384 bool ConcurrentMarkSweepGeneration::grow_by(size_t bytes) { | |
| 3385 assert_locked_or_safepoint(Heap_lock); | |
| 3386 bool result = _virtual_space.expand_by(bytes); | |
| 3387 if (result) { | |
| 3388 HeapWord* old_end = _cmsSpace->end(); | |
| 3389 size_t new_word_size = | |
| 3390 heap_word_size(_virtual_space.committed_size()); | |
| 3391 MemRegion mr(_cmsSpace->bottom(), new_word_size); | |
| 3392 _bts->resize(new_word_size); // resize the block offset shared array | |
| 3393 Universe::heap()->barrier_set()->resize_covered_region(mr); | |
| 3394 // Hmmmm... why doesn't CFLS::set_end verify locking? | |
| 3395 // This is quite ugly; FIX ME XXX | |
|
1145
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
3396 _cmsSpace->assert_locked(freelistLock()); |
| 0 | 3397 _cmsSpace->set_end((HeapWord*)_virtual_space.high()); |
| 3398 | |
| 3399 // update the space and generation capacity counters | |
| 3400 if (UsePerfData) { | |
| 3401 _space_counters->update_capacity(); | |
| 3402 _gen_counters->update_all(); | |
| 3403 } | |
| 3404 | |
| 3405 if (Verbose && PrintGC) { | |
| 3406 size_t new_mem_size = _virtual_space.committed_size(); | |
| 3407 size_t old_mem_size = new_mem_size - bytes; | |
|
7623
203f64878aab
7102489: RFE: cleanup jlong typedef on __APPLE__and _LLP64 systems.
hseigel
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6885
diff
changeset
|
3408 gclog_or_tty->print_cr("Expanding %s from " SIZE_FORMAT "K by " SIZE_FORMAT "K to " SIZE_FORMAT "K", |
| 0 | 3409 name(), old_mem_size/K, bytes/K, new_mem_size/K); |
| 3410 } | |
| 3411 } | |
| 3412 return result; | |
| 3413 } | |
| 3414 | |
| 3415 bool ConcurrentMarkSweepGeneration::grow_to_reserved() { | |
| 3416 assert_locked_or_safepoint(Heap_lock); | |
| 3417 bool success = true; | |
| 3418 const size_t remaining_bytes = _virtual_space.uncommitted_size(); | |
| 3419 if (remaining_bytes > 0) { | |
| 3420 success = grow_by(remaining_bytes); | |
| 3421 DEBUG_ONLY(if (!success) warning("grow to reserved failed");) | |
| 3422 } | |
| 3423 return success; | |
| 3424 } | |
| 3425 | |
|
9072
8617e38bb4cb
8008508: CMS does not correctly reduce heap size after a Full GC
jmasa
parents:
8784
diff
changeset
|
3426 void ConcurrentMarkSweepGeneration::shrink_free_list_by(size_t bytes) { |
| 0 | 3427 assert_locked_or_safepoint(Heap_lock); |
| 3428 assert_lock_strong(freelistLock()); | |
|
10180
ebded0261dfc
8012111: Remove warning about CMS generation shrinking.
jmasa
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9152
diff
changeset
|
3429 if (PrintGCDetails && Verbose) { |
|
ebded0261dfc
8012111: Remove warning about CMS generation shrinking.
jmasa
parents:
9152
diff
changeset
|
3430 warning("Shrinking of CMS not yet implemented"); |
|
ebded0261dfc
8012111: Remove warning about CMS generation shrinking.
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diff
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|
3431 } |
| 0 | 3432 return; |
| 3433 } | |
| 3434 | |
| 3435 | |
| 3436 // Simple ctor/dtor wrapper for accounting & timer chores around concurrent | |
| 3437 // phases. | |
| 3438 class CMSPhaseAccounting: public StackObj { | |
| 3439 public: | |
| 3440 CMSPhaseAccounting(CMSCollector *collector, | |
| 3441 const char *phase, | |
| 3442 bool print_cr = true); | |
| 3443 ~CMSPhaseAccounting(); | |
| 3444 | |
| 3445 private: | |
| 3446 CMSCollector *_collector; | |
| 3447 const char *_phase; | |
| 3448 elapsedTimer _wallclock; | |
| 3449 bool _print_cr; | |
| 3450 | |
| 3451 public: | |
| 3452 // Not MT-safe; so do not pass around these StackObj's | |
| 3453 // where they may be accessed by other threads. | |
| 3454 jlong wallclock_millis() { | |
| 3455 assert(_wallclock.is_active(), "Wall clock should not stop"); | |
| 3456 _wallclock.stop(); // to record time | |
| 3457 jlong ret = _wallclock.milliseconds(); | |
| 3458 _wallclock.start(); // restart | |
| 3459 return ret; | |
| 3460 } | |
| 3461 }; | |
| 3462 | |
| 3463 CMSPhaseAccounting::CMSPhaseAccounting(CMSCollector *collector, | |
| 3464 const char *phase, | |
| 3465 bool print_cr) : | |
| 3466 _collector(collector), _phase(phase), _print_cr(print_cr) { | |
| 3467 | |
| 3468 if (PrintCMSStatistics != 0) { | |
| 3469 _collector->resetYields(); | |
| 3470 } | |
|
8740
62609ffa2fc6
8008684: CMS: concurrent phase start markers should always be printed
tschatzl
parents:
8736
diff
changeset
|
3471 if (PrintGCDetails) { |
| 0 | 3472 gclog_or_tty->date_stamp(PrintGCDateStamps); |
|
8740
62609ffa2fc6
8008684: CMS: concurrent phase start markers should always be printed
tschatzl
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8736
diff
changeset
|
3473 gclog_or_tty->stamp(PrintGCTimeStamps); |
|
62609ffa2fc6
8008684: CMS: concurrent phase start markers should always be printed
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8736
diff
changeset
|
3474 gclog_or_tty->print_cr("[%s-concurrent-%s-start]", |
| 0 | 3475 _collector->cmsGen()->short_name(), _phase); |
| 3476 } | |
| 3477 _collector->resetTimer(); | |
| 3478 _wallclock.start(); | |
| 3479 _collector->startTimer(); | |
| 3480 } | |
| 3481 | |
| 3482 CMSPhaseAccounting::~CMSPhaseAccounting() { | |
| 3483 assert(_wallclock.is_active(), "Wall clock should not have stopped"); | |
| 3484 _collector->stopTimer(); | |
| 3485 _wallclock.stop(); | |
| 3486 if (PrintGCDetails) { | |
| 3487 gclog_or_tty->date_stamp(PrintGCDateStamps); | |
|
6752
9646b7ff4d14
7198130: G1: PrintReferenceGC output comes out of order
brutisso
parents:
6725
diff
changeset
|
3488 gclog_or_tty->stamp(PrintGCTimeStamps); |
| 0 | 3489 gclog_or_tty->print("[%s-concurrent-%s: %3.3f/%3.3f secs]", |
| 3490 _collector->cmsGen()->short_name(), | |
| 3491 _phase, _collector->timerValue(), _wallclock.seconds()); | |
| 3492 if (_print_cr) { | |
| 3493 gclog_or_tty->print_cr(""); | |
| 3494 } | |
| 3495 if (PrintCMSStatistics != 0) { | |
| 3496 gclog_or_tty->print_cr(" (CMS-concurrent-%s yielded %d times)", _phase, | |
| 3497 _collector->yields()); | |
| 3498 } | |
| 3499 } | |
| 3500 } | |
| 3501 | |
| 3502 // CMS work | |
| 3503 | |
| 3504 // Checkpoint the roots into this generation from outside | |
| 3505 // this generation. [Note this initial checkpoint need only | |
| 3506 // be approximate -- we'll do a catch up phase subsequently.] | |
| 3507 void CMSCollector::checkpointRootsInitial(bool asynch) { | |
| 3508 assert(_collectorState == InitialMarking, "Wrong collector state"); | |
| 3509 check_correct_thread_executing(); | |
|
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
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3293
diff
changeset
|
3510 TraceCMSMemoryManagerStats tms(_collectorState,GenCollectedHeap::heap()->gc_cause()); |
|
2125
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6458402: 3 jvmti tests fail with CMS and +ExplicitGCInvokesConcurrent
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1994
diff
changeset
|
3511 |
| 0 | 3512 ReferenceProcessor* rp = ref_processor(); |
| 3513 SpecializationStats::clear(); | |
| 3514 assert(_restart_addr == NULL, "Control point invariant"); | |
| 3515 if (asynch) { | |
| 3516 // acquire locks for subsequent manipulations | |
| 3517 MutexLockerEx x(bitMapLock(), | |
| 3518 Mutex::_no_safepoint_check_flag); | |
| 3519 checkpointRootsInitialWork(asynch); | |
|
3979
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3827
diff
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|
3520 // enable ("weak") refs discovery |
|
4dfb2df418f2
6484982: G1: process references during evacuation pauses
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3827
diff
changeset
|
3521 rp->enable_discovery(true /*verify_disabled*/, true /*check_no_refs*/); |
| 0 | 3522 _collectorState = Marking; |
| 3523 } else { | |
| 3524 // (Weak) Refs discovery: this is controlled from genCollectedHeap::do_collection | |
| 3525 // which recognizes if we are a CMS generation, and doesn't try to turn on | |
| 3526 // discovery; verify that they aren't meddling. | |
| 3527 assert(!rp->discovery_is_atomic(), | |
| 3528 "incorrect setting of discovery predicate"); | |
| 3529 assert(!rp->discovery_enabled(), "genCollectedHeap shouldn't control " | |
| 3530 "ref discovery for this generation kind"); | |
| 3531 // already have locks | |
| 3532 checkpointRootsInitialWork(asynch); | |
|
3979
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6484982: G1: process references during evacuation pauses
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3827
diff
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|
3533 // now enable ("weak") refs discovery |
|
4dfb2df418f2
6484982: G1: process references during evacuation pauses
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3827
diff
changeset
|
3534 rp->enable_discovery(true /*verify_disabled*/, false /*verify_no_refs*/); |
| 0 | 3535 _collectorState = Marking; |
| 3536 } | |
| 3537 SpecializationStats::print(); | |
| 3538 } | |
| 3539 | |
| 3540 void CMSCollector::checkpointRootsInitialWork(bool asynch) { | |
| 3541 assert(SafepointSynchronize::is_at_safepoint(), "world should be stopped"); | |
| 3542 assert(_collectorState == InitialMarking, "just checking"); | |
| 3543 | |
| 3544 // If there has not been a GC[n-1] since last GC[n] cycle completed, | |
| 3545 // precede our marking with a collection of all | |
| 3546 // younger generations to keep floating garbage to a minimum. | |
| 3547 // XXX: we won't do this for now -- it's an optimization to be done later. | |
| 3548 | |
| 3549 // already have locks | |
| 3550 assert_lock_strong(bitMapLock()); | |
| 3551 assert(_markBitMap.isAllClear(), "was reset at end of previous cycle"); | |
| 3552 | |
| 3553 // Setup the verification and class unloading state for this | |
| 3554 // CMS collection cycle. | |
| 3555 setup_cms_unloading_and_verification_state(); | |
| 3556 | |
| 3557 NOT_PRODUCT(TraceTime t("\ncheckpointRootsInitialWork", | |
| 3558 PrintGCDetails && Verbose, true, gclog_or_tty);) | |
| 3559 if (UseAdaptiveSizePolicy) { | |
| 3560 size_policy()->checkpoint_roots_initial_begin(); | |
| 3561 } | |
| 3562 | |
| 3563 // Reset all the PLAB chunk arrays if necessary. | |
| 3564 if (_survivor_plab_array != NULL && !CMSPLABRecordAlways) { | |
| 3565 reset_survivor_plab_arrays(); | |
| 3566 } | |
| 3567 | |
| 3568 ResourceMark rm; | |
| 3569 HandleMark hm; | |
| 3570 | |
| 3571 FalseClosure falseClosure; | |
| 3572 // In the case of a synchronous collection, we will elide the | |
| 3573 // remark step, so it's important to catch all the nmethod oops | |
|
994
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3574 // in this step. |
|
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3575 // The final 'true' flag to gen_process_strong_roots will ensure this. |
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3576 // If 'async' is true, we can relax the nmethod tracing. |
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|
3577 MarkRefsIntoClosure notOlder(_span, &_markBitMap); |
| 0 | 3578 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
| 3579 | |
| 3580 verify_work_stacks_empty(); | |
| 3581 verify_overflow_empty(); | |
| 3582 | |
| 3583 gch->ensure_parsability(false); // fill TLABs, but no need to retire them | |
| 3584 // Update the saved marks which may affect the root scans. | |
| 3585 gch->save_marks(); | |
| 3586 | |
| 3587 // weak reference processing has not started yet. | |
| 3588 ref_processor()->set_enqueuing_is_done(false); | |
| 3589 | |
|
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3590 // Need to remember all newly created CLDs, |
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3591 // so that we can guarantee that the remark finds them. |
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3592 ClassLoaderDataGraph::remember_new_clds(true); |
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3593 |
|
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3594 // Whenever a CLD is found, it will be claimed before proceeding to mark |
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3595 // the klasses. The claimed marks need to be cleared before marking starts. |
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3596 ClassLoaderDataGraph::clear_claimed_marks(); |
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3597 |
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3598 CMKlassClosure klass_closure(¬Older); |
| 0 | 3599 { |
| 3600 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact;) | |
| 3601 gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel. | |
| 3602 gch->gen_process_strong_roots(_cmsGen->level(), | |
| 3603 true, // younger gens are roots | |
|
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3604 true, // activate StrongRootsScope |
|
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3605 false, // not scavenging |
| 0 | 3606 SharedHeap::ScanningOption(roots_scanning_options()), |
|
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3607 ¬Older, |
|
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3608 true, // walk all of code cache if (so & SO_CodeCache) |
|
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3609 NULL, |
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|
3610 &klass_closure); |
| 0 | 3611 } |
| 3612 | |
| 3613 // Clear mod-union table; it will be dirtied in the prologue of | |
| 3614 // CMS generation per each younger generation collection. | |
| 3615 | |
| 3616 assert(_modUnionTable.isAllClear(), | |
| 3617 "Was cleared in most recent final checkpoint phase" | |
| 3618 " or no bits are set in the gc_prologue before the start of the next " | |
| 3619 "subsequent marking phase."); | |
| 3620 | |
|
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3621 assert(_ct->klass_rem_set()->mod_union_is_clear(), "Must be"); |
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3622 |
| 0 | 3623 // Save the end of the used_region of the constituent generations |
| 3624 // to be used to limit the extent of sweep in each generation. | |
| 3625 save_sweep_limits(); | |
| 3626 if (UseAdaptiveSizePolicy) { | |
| 3627 size_policy()->checkpoint_roots_initial_end(gch->gc_cause()); | |
| 3628 } | |
| 3629 verify_overflow_empty(); | |
| 3630 } | |
| 3631 | |
| 3632 bool CMSCollector::markFromRoots(bool asynch) { | |
| 3633 // we might be tempted to assert that: | |
| 3634 // assert(asynch == !SafepointSynchronize::is_at_safepoint(), | |
| 3635 // "inconsistent argument?"); | |
| 3636 // However that wouldn't be right, because it's possible that | |
| 3637 // a safepoint is indeed in progress as a younger generation | |
| 3638 // stop-the-world GC happens even as we mark in this generation. | |
| 3639 assert(_collectorState == Marking, "inconsistent state?"); | |
| 3640 check_correct_thread_executing(); | |
| 3641 verify_overflow_empty(); | |
| 3642 | |
| 3643 bool res; | |
| 3644 if (asynch) { | |
| 3645 | |
| 3646 // Start the timers for adaptive size policy for the concurrent phases | |
| 3647 // Do it here so that the foreground MS can use the concurrent | |
| 3648 // timer since a foreground MS might has the sweep done concurrently | |
| 3649 // or STW. | |
| 3650 if (UseAdaptiveSizePolicy) { | |
| 3651 size_policy()->concurrent_marking_begin(); | |
| 3652 } | |
| 3653 | |
| 3654 // Weak ref discovery note: We may be discovering weak | |
| 3655 // refs in this generation concurrent (but interleaved) with | |
| 3656 // weak ref discovery by a younger generation collector. | |
| 3657 | |
| 3658 CMSTokenSyncWithLocks ts(true, bitMapLock()); | |
| 3659 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
| 3660 CMSPhaseAccounting pa(this, "mark", !PrintGCDetails); | |
| 3661 res = markFromRootsWork(asynch); | |
| 3662 if (res) { | |
| 3663 _collectorState = Precleaning; | |
| 3664 } else { // We failed and a foreground collection wants to take over | |
| 3665 assert(_foregroundGCIsActive, "internal state inconsistency"); | |
| 3666 assert(_restart_addr == NULL, "foreground will restart from scratch"); | |
| 3667 if (PrintGCDetails) { | |
| 3668 gclog_or_tty->print_cr("bailing out to foreground collection"); | |
| 3669 } | |
| 3670 } | |
| 3671 if (UseAdaptiveSizePolicy) { | |
| 3672 size_policy()->concurrent_marking_end(); | |
| 3673 } | |
| 3674 } else { | |
| 3675 assert(SafepointSynchronize::is_at_safepoint(), | |
| 3676 "inconsistent with asynch == false"); | |
| 3677 if (UseAdaptiveSizePolicy) { | |
| 3678 size_policy()->ms_collection_marking_begin(); | |
| 3679 } | |
| 3680 // already have locks | |
| 3681 res = markFromRootsWork(asynch); | |
| 3682 _collectorState = FinalMarking; | |
| 3683 if (UseAdaptiveSizePolicy) { | |
| 3684 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 3685 size_policy()->ms_collection_marking_end(gch->gc_cause()); | |
| 3686 } | |
| 3687 } | |
| 3688 verify_overflow_empty(); | |
| 3689 return res; | |
| 3690 } | |
| 3691 | |
| 3692 bool CMSCollector::markFromRootsWork(bool asynch) { | |
| 3693 // iterate over marked bits in bit map, doing a full scan and mark | |
| 3694 // from these roots using the following algorithm: | |
| 3695 // . if oop is to the right of the current scan pointer, | |
| 3696 // mark corresponding bit (we'll process it later) | |
| 3697 // . else (oop is to left of current scan pointer) | |
| 3698 // push oop on marking stack | |
| 3699 // . drain the marking stack | |
| 3700 | |
| 3701 // Note that when we do a marking step we need to hold the | |
| 3702 // bit map lock -- recall that direct allocation (by mutators) | |
| 3703 // and promotion (by younger generation collectors) is also | |
| 3704 // marking the bit map. [the so-called allocate live policy.] | |
| 3705 // Because the implementation of bit map marking is not | |
| 3706 // robust wrt simultaneous marking of bits in the same word, | |
| 3707 // we need to make sure that there is no such interference | |
| 3708 // between concurrent such updates. | |
| 3709 | |
| 3710 // already have locks | |
| 3711 assert_lock_strong(bitMapLock()); | |
| 3712 | |
| 3713 verify_work_stacks_empty(); | |
| 3714 verify_overflow_empty(); | |
| 3715 bool result = false; | |
| 1284 | 3716 if (CMSConcurrentMTEnabled && ConcGCThreads > 0) { |
| 0 | 3717 result = do_marking_mt(asynch); |
| 3718 } else { | |
| 3719 result = do_marking_st(asynch); | |
| 3720 } | |
| 3721 return result; | |
| 3722 } | |
| 3723 | |
| 3724 // Forward decl | |
| 3725 class CMSConcMarkingTask; | |
| 3726 | |
| 3727 class CMSConcMarkingTerminator: public ParallelTaskTerminator { | |
| 3728 CMSCollector* _collector; | |
| 3729 CMSConcMarkingTask* _task; | |
|
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3730 public: |
| 0 | 3731 virtual void yield(); |
|
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3732 |
| 0 | 3733 // "n_threads" is the number of threads to be terminated. |
| 3734 // "queue_set" is a set of work queues of other threads. | |
| 3735 // "collector" is the CMS collector associated with this task terminator. | |
| 3736 // "yield" indicates whether we need the gang as a whole to yield. | |
|
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3737 CMSConcMarkingTerminator(int n_threads, TaskQueueSetSuper* queue_set, CMSCollector* collector) : |
| 0 | 3738 ParallelTaskTerminator(n_threads, queue_set), |
|
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3739 _collector(collector) { } |
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3740 |
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3741 void set_task(CMSConcMarkingTask* task) { |
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3742 _task = task; |
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3743 } |
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|
3744 }; |
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|
3745 |
|
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|
3746 class CMSConcMarkingTerminatorTerminator: public TerminatorTerminator { |
|
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|
3747 CMSConcMarkingTask* _task; |
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3748 public: |
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|
3749 bool should_exit_termination(); |
| 0 | 3750 void set_task(CMSConcMarkingTask* task) { |
| 3751 _task = task; | |
| 3752 } | |
| 3753 }; | |
| 3754 | |
| 3755 // MT Concurrent Marking Task | |
| 3756 class CMSConcMarkingTask: public YieldingFlexibleGangTask { | |
| 3757 CMSCollector* _collector; | |
| 3758 int _n_workers; // requested/desired # workers | |
| 3759 bool _asynch; | |
| 3760 bool _result; | |
| 3761 CompactibleFreeListSpace* _cms_space; | |
|
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3762 char _pad_front[64]; // padding to ... |
|
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|
3763 HeapWord* _global_finger; // ... avoid sharing cache line |
|
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3764 char _pad_back[64]; |
|
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3765 HeapWord* _restart_addr; |
| 0 | 3766 |
| 3767 // Exposed here for yielding support | |
| 3768 Mutex* const _bit_map_lock; | |
| 3769 | |
| 3770 // The per thread work queues, available here for stealing | |
| 3771 OopTaskQueueSet* _task_queues; | |
|
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|
3772 |
|
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|
3773 // Termination (and yielding) support |
| 0 | 3774 CMSConcMarkingTerminator _term; |
|
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|
3775 CMSConcMarkingTerminatorTerminator _term_term; |
| 0 | 3776 |
| 3777 public: | |
| 3778 CMSConcMarkingTask(CMSCollector* collector, | |
| 3779 CompactibleFreeListSpace* cms_space, | |
|
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|
3780 bool asynch, |
| 0 | 3781 YieldingFlexibleWorkGang* workers, |
| 3782 OopTaskQueueSet* task_queues): | |
| 3783 YieldingFlexibleGangTask("Concurrent marking done multi-threaded"), | |
| 3784 _collector(collector), | |
| 3785 _cms_space(cms_space), | |
|
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3786 _asynch(asynch), _n_workers(0), _result(true), |
|
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3787 _task_queues(task_queues), |
|
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3788 _term(_n_workers, task_queues, _collector), |
| 0 | 3789 _bit_map_lock(collector->bitMapLock()) |
| 3790 { | |
|
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3791 _requested_size = _n_workers; |
| 0 | 3792 _term.set_task(this); |
|
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3793 _term_term.set_task(this); |
|
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3794 _restart_addr = _global_finger = _cms_space->bottom(); |
| 0 | 3795 } |
| 3796 | |
| 3797 | |
| 3798 OopTaskQueueSet* task_queues() { return _task_queues; } | |
| 3799 | |
| 3800 OopTaskQueue* work_queue(int i) { return task_queues()->queue(i); } | |
| 3801 | |
| 3802 HeapWord** global_finger_addr() { return &_global_finger; } | |
| 3803 | |
| 3804 CMSConcMarkingTerminator* terminator() { return &_term; } | |
| 3805 | |
|
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3806 virtual void set_for_termination(int active_workers) { |
|
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3807 terminator()->reset_for_reuse(active_workers); |
|
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3808 } |
|
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3809 |
|
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3810 void work(uint worker_id); |
|
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3811 bool should_yield() { |
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3812 return ConcurrentMarkSweepThread::should_yield() |
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3813 && !_collector->foregroundGCIsActive() |
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3814 && _asynch; |
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|
3815 } |
| 0 | 3816 |
| 3817 virtual void coordinator_yield(); // stuff done by coordinator | |
| 3818 bool result() { return _result; } | |
| 3819 | |
| 3820 void reset(HeapWord* ra) { | |
|
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3821 assert(_global_finger >= _cms_space->end(), "Postcondition of ::work(i)"); |
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3822 _restart_addr = _global_finger = ra; |
| 0 | 3823 _term.reset_for_reuse(); |
| 3824 } | |
| 3825 | |
| 3826 static bool get_work_from_overflow_stack(CMSMarkStack* ovflw_stk, | |
| 3827 OopTaskQueue* work_q); | |
| 3828 | |
| 3829 private: | |
| 3830 void do_scan_and_mark(int i, CompactibleFreeListSpace* sp); | |
| 3831 void do_work_steal(int i); | |
| 3832 void bump_global_finger(HeapWord* f); | |
| 3833 }; | |
| 3834 | |
|
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3835 bool CMSConcMarkingTerminatorTerminator::should_exit_termination() { |
|
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|
3836 assert(_task != NULL, "Error"); |
|
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3837 return _task->yielding(); |
|
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|
3838 // Note that we do not need the disjunct || _task->should_yield() above |
|
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3839 // because we want terminating threads to yield only if the task |
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3840 // is already in the midst of yielding, which happens only after at least one |
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3841 // thread has yielded. |
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3842 } |
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3843 |
| 0 | 3844 void CMSConcMarkingTerminator::yield() { |
|
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3845 if (_task->should_yield()) { |
| 0 | 3846 _task->yield(); |
| 3847 } else { | |
| 3848 ParallelTaskTerminator::yield(); | |
| 3849 } | |
| 3850 } | |
| 3851 | |
| 3852 //////////////////////////////////////////////////////////////// | |
| 3853 // Concurrent Marking Algorithm Sketch | |
| 3854 //////////////////////////////////////////////////////////////// | |
| 3855 // Until all tasks exhausted (both spaces): | |
| 3856 // -- claim next available chunk | |
| 3857 // -- bump global finger via CAS | |
| 3858 // -- find first object that starts in this chunk | |
| 3859 // and start scanning bitmap from that position | |
| 3860 // -- scan marked objects for oops | |
| 3861 // -- CAS-mark target, and if successful: | |
| 3862 // . if target oop is above global finger (volatile read) | |
| 3863 // nothing to do | |
| 3864 // . if target oop is in chunk and above local finger | |
| 3865 // then nothing to do | |
| 3866 // . else push on work-queue | |
| 3867 // -- Deal with possible overflow issues: | |
| 3868 // . local work-queue overflow causes stuff to be pushed on | |
| 3869 // global (common) overflow queue | |
| 3870 // . always first empty local work queue | |
| 3871 // . then get a batch of oops from global work queue if any | |
| 3872 // . then do work stealing | |
| 3873 // -- When all tasks claimed (both spaces) | |
| 3874 // and local work queue empty, | |
| 3875 // then in a loop do: | |
| 3876 // . check global overflow stack; steal a batch of oops and trace | |
| 3877 // . try to steal from other threads oif GOS is empty | |
| 3878 // . if neither is available, offer termination | |
| 3879 // -- Terminate and return result | |
| 3880 // | |
|
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3881 void CMSConcMarkingTask::work(uint worker_id) { |
| 0 | 3882 elapsedTimer _timer; |
| 3883 ResourceMark rm; | |
| 3884 HandleMark hm; | |
| 3885 | |
| 3886 DEBUG_ONLY(_collector->verify_overflow_empty();) | |
| 3887 | |
| 3888 // Before we begin work, our work queue should be empty | |
|
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3889 assert(work_queue(worker_id)->size() == 0, "Expected to be empty"); |
| 0 | 3890 // Scan the bitmap covering _cms_space, tracing through grey objects. |
| 3891 _timer.start(); | |
|
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3892 do_scan_and_mark(worker_id, _cms_space); |
| 0 | 3893 _timer.stop(); |
| 3894 if (PrintCMSStatistics != 0) { | |
| 3895 gclog_or_tty->print_cr("Finished cms space scanning in %dth thread: %3.3f sec", | |
|
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3896 worker_id, _timer.seconds()); |
|
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3897 // XXX: need xxx/xxx type of notation, two timers |
| 0 | 3898 } |
| 3899 | |
| 3900 // ... do work stealing | |
| 3901 _timer.reset(); | |
| 3902 _timer.start(); | |
|
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|
3903 do_work_steal(worker_id); |
| 0 | 3904 _timer.stop(); |
| 3905 if (PrintCMSStatistics != 0) { | |
| 3906 gclog_or_tty->print_cr("Finished work stealing in %dth thread: %3.3f sec", | |
|
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|
3907 worker_id, _timer.seconds()); |
|
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3908 // XXX: need xxx/xxx type of notation, two timers |
| 0 | 3909 } |
| 3910 assert(_collector->_markStack.isEmpty(), "Should have been emptied"); | |
|
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3911 assert(work_queue(worker_id)->size() == 0, "Should have been emptied"); |
| 0 | 3912 // Note that under the current task protocol, the |
| 3913 // following assertion is true even of the spaces | |
| 3914 // expanded since the completion of the concurrent | |
| 3915 // marking. XXX This will likely change under a strict | |
| 3916 // ABORT semantics. | |
|
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3917 // After perm removal the comparison was changed to |
|
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3918 // greater than or equal to from strictly greater than. |
|
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3919 // Before perm removal the highest address sweep would |
|
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3920 // have been at the end of perm gen but now is at the |
|
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3921 // end of the tenured gen. |
|
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|
3922 assert(_global_finger >= _cms_space->end(), |
| 0 | 3923 "All tasks have been completed"); |
| 3924 DEBUG_ONLY(_collector->verify_overflow_empty();) | |
| 3925 } | |
| 3926 | |
| 3927 void CMSConcMarkingTask::bump_global_finger(HeapWord* f) { | |
| 3928 HeapWord* read = _global_finger; | |
| 3929 HeapWord* cur = read; | |
| 3930 while (f > read) { | |
| 3931 cur = read; | |
| 3932 read = (HeapWord*) Atomic::cmpxchg_ptr(f, &_global_finger, cur); | |
| 3933 if (cur == read) { | |
| 3934 // our cas succeeded | |
| 3935 assert(_global_finger >= f, "protocol consistency"); | |
| 3936 break; | |
| 3937 } | |
| 3938 } | |
| 3939 } | |
| 3940 | |
| 3941 // This is really inefficient, and should be redone by | |
| 3942 // using (not yet available) block-read and -write interfaces to the | |
| 3943 // stack and the work_queue. XXX FIX ME !!! | |
| 3944 bool CMSConcMarkingTask::get_work_from_overflow_stack(CMSMarkStack* ovflw_stk, | |
| 3945 OopTaskQueue* work_q) { | |
| 3946 // Fast lock-free check | |
| 3947 if (ovflw_stk->length() == 0) { | |
| 3948 return false; | |
| 3949 } | |
| 3950 assert(work_q->size() == 0, "Shouldn't steal"); | |
| 3951 MutexLockerEx ml(ovflw_stk->par_lock(), | |
| 3952 Mutex::_no_safepoint_check_flag); | |
| 3953 // Grab up to 1/4 the size of the work queue | |
|
679
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|
3954 size_t num = MIN2((size_t)(work_q->max_elems() - work_q->size())/4, |
| 0 | 3955 (size_t)ParGCDesiredObjsFromOverflowList); |
| 3956 num = MIN2(num, ovflw_stk->length()); | |
| 3957 for (int i = (int) num; i > 0; i--) { | |
| 3958 oop cur = ovflw_stk->pop(); | |
| 3959 assert(cur != NULL, "Counted wrong?"); | |
| 3960 work_q->push(cur); | |
| 3961 } | |
| 3962 return num > 0; | |
| 3963 } | |
| 3964 | |
| 3965 void CMSConcMarkingTask::do_scan_and_mark(int i, CompactibleFreeListSpace* sp) { | |
| 3966 SequentialSubTasksDone* pst = sp->conc_par_seq_tasks(); | |
| 3967 int n_tasks = pst->n_tasks(); | |
| 3968 // We allow that there may be no tasks to do here because | |
| 3969 // we are restarting after a stack overflow. | |
|
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3970 assert(pst->valid() || n_tasks == 0, "Uninitialized use?"); |
|
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3971 uint nth_task = 0; |
| 0 | 3972 |
|
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3973 HeapWord* aligned_start = sp->bottom(); |
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3974 if (sp->used_region().contains(_restart_addr)) { |
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3975 // Align down to a card boundary for the start of 0th task |
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3976 // for this space. |
|
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|
3977 aligned_start = |
|
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|
3978 (HeapWord*)align_size_down((uintptr_t)_restart_addr, |
|
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|
3979 CardTableModRefBS::card_size); |
|
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|
3980 } |
|
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|
3981 |
| 0 | 3982 size_t chunk_size = sp->marking_task_size(); |
| 3983 while (!pst->is_task_claimed(/* reference */ nth_task)) { | |
| 3984 // Having claimed the nth task in this space, | |
| 3985 // compute the chunk that it corresponds to: | |
|
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3986 MemRegion span = MemRegion(aligned_start + nth_task*chunk_size, |
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|
3987 aligned_start + (nth_task+1)*chunk_size); |
| 0 | 3988 // Try and bump the global finger via a CAS; |
| 3989 // note that we need to do the global finger bump | |
| 3990 // _before_ taking the intersection below, because | |
| 3991 // the task corresponding to that region will be | |
| 3992 // deemed done even if the used_region() expands | |
| 3993 // because of allocation -- as it almost certainly will | |
| 3994 // during start-up while the threads yield in the | |
| 3995 // closure below. | |
| 3996 HeapWord* finger = span.end(); | |
| 3997 bump_global_finger(finger); // atomically | |
| 3998 // There are null tasks here corresponding to chunks | |
| 3999 // beyond the "top" address of the space. | |
| 4000 span = span.intersection(sp->used_region()); | |
| 4001 if (!span.is_empty()) { // Non-null task | |
|
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|
4002 HeapWord* prev_obj; |
|
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|
4003 assert(!span.contains(_restart_addr) || nth_task == 0, |
|
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|
4004 "Inconsistency"); |
|
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|
4005 if (nth_task == 0) { |
|
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|
4006 // For the 0th task, we'll not need to compute a block_start. |
|
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|
4007 if (span.contains(_restart_addr)) { |
|
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|
4008 // In the case of a restart because of stack overflow, |
|
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|
4009 // we might additionally skip a chunk prefix. |
|
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|
4010 prev_obj = _restart_addr; |
| 0 | 4011 } else { |
|
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|
4012 prev_obj = span.start(); |
|
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|
4013 } |
|
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|
4014 } else { |
|
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|
4015 // We want to skip the first object because |
|
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|
4016 // the protocol is to scan any object in its entirety |
|
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|
4017 // that _starts_ in this span; a fortiori, any |
|
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|
4018 // object starting in an earlier span is scanned |
|
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|
4019 // as part of an earlier claimed task. |
|
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|
4020 // Below we use the "careful" version of block_start |
|
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|
4021 // so we do not try to navigate uninitialized objects. |
|
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|
4022 prev_obj = sp->block_start_careful(span.start()); |
|
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|
4023 // Below we use a variant of block_size that uses the |
|
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|
4024 // Printezis bits to avoid waiting for allocated |
|
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|
4025 // objects to become initialized/parsable. |
|
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|
4026 while (prev_obj < span.start()) { |
|
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|
4027 size_t sz = sp->block_size_no_stall(prev_obj, _collector); |
|
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|
4028 if (sz > 0) { |
|
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|
4029 prev_obj += sz; |
|
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|
4030 } else { |
|
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|
4031 // In this case we may end up doing a bit of redundant |
|
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|
4032 // scanning, but that appears unavoidable, short of |
|
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|
4033 // locking the free list locks; see bug 6324141. |
|
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|
4034 break; |
|
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|
4035 } |
| 0 | 4036 } |
| 4037 } | |
| 4038 if (prev_obj < span.end()) { | |
| 4039 MemRegion my_span = MemRegion(prev_obj, span.end()); | |
| 4040 // Do the marking work within a non-empty span -- | |
| 4041 // the last argument to the constructor indicates whether the | |
| 4042 // iteration should be incremental with periodic yields. | |
| 4043 Par_MarkFromRootsClosure cl(this, _collector, my_span, | |
| 4044 &_collector->_markBitMap, | |
| 4045 work_queue(i), | |
| 4046 &_collector->_markStack, | |
| 4047 _asynch); | |
| 4048 _collector->_markBitMap.iterate(&cl, my_span.start(), my_span.end()); | |
| 4049 } // else nothing to do for this task | |
| 4050 } // else nothing to do for this task | |
| 4051 } | |
| 4052 // We'd be tempted to assert here that since there are no | |
| 4053 // more tasks left to claim in this space, the global_finger | |
| 4054 // must exceed space->top() and a fortiori space->end(). However, | |
| 4055 // that would not quite be correct because the bumping of | |
| 4056 // global_finger occurs strictly after the claiming of a task, | |
| 4057 // so by the time we reach here the global finger may not yet | |
| 4058 // have been bumped up by the thread that claimed the last | |
| 4059 // task. | |
| 4060 pst->all_tasks_completed(); | |
| 4061 } | |
| 4062 | |
|
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4063 class Par_ConcMarkingClosure: public CMSOopClosure { |
|
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4064 private: |
|
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|
4065 CMSCollector* _collector; |
|
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|
4066 CMSConcMarkingTask* _task; |
| 0 | 4067 MemRegion _span; |
| 4068 CMSBitMap* _bit_map; | |
| 4069 CMSMarkStack* _overflow_stack; | |
| 4070 OopTaskQueue* _work_queue; | |
|
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4071 protected: |
|
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4072 DO_OOP_WORK_DEFN |
| 0 | 4073 public: |
|
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|
4074 Par_ConcMarkingClosure(CMSCollector* collector, CMSConcMarkingTask* task, OopTaskQueue* work_queue, |
|
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4075 CMSBitMap* bit_map, CMSMarkStack* overflow_stack): |
|
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|
4076 CMSOopClosure(collector->ref_processor()), |
|
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|
4077 _collector(collector), |
|
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|
4078 _task(task), |
|
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|
4079 _span(collector->_span), |
| 0 | 4080 _work_queue(work_queue), |
| 4081 _bit_map(bit_map), | |
| 935 | 4082 _overflow_stack(overflow_stack) |
| 4083 { } | |
|
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4084 virtual void do_oop(oop* p); |
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4085 virtual void do_oop(narrowOop* p); |
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4086 |
| 0 | 4087 void trim_queue(size_t max); |
| 4088 void handle_stack_overflow(HeapWord* lost); | |
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4089 void do_yield_check() { |
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4090 if (_task->should_yield()) { |
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4091 _task->yield(); |
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4092 } |
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4093 } |
| 0 | 4094 }; |
| 4095 | |
|
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4096 // Grey object scanning during work stealing phase -- |
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4097 // the salient assumption here is that any references |
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4098 // that are in these stolen objects being scanned must |
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4099 // already have been initialized (else they would not have |
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4100 // been published), so we do not need to check for |
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4101 // uninitialized objects before pushing here. |
|
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4102 void Par_ConcMarkingClosure::do_oop(oop obj) { |
|
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4103 assert(obj->is_oop_or_null(true), "expected an oop or NULL"); |
|
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4104 HeapWord* addr = (HeapWord*)obj; |
| 0 | 4105 // Check if oop points into the CMS generation |
| 4106 // and is not marked | |
| 4107 if (_span.contains(addr) && !_bit_map->isMarked(addr)) { | |
| 4108 // a white object ... | |
| 4109 // If we manage to "claim" the object, by being the | |
| 4110 // first thread to mark it, then we push it on our | |
| 4111 // marking stack | |
| 4112 if (_bit_map->par_mark(addr)) { // ... now grey | |
| 4113 // push on work queue (grey set) | |
| 4114 bool simulate_overflow = false; | |
| 4115 NOT_PRODUCT( | |
| 4116 if (CMSMarkStackOverflowALot && | |
| 4117 _collector->simulate_overflow()) { | |
| 4118 // simulate a stack overflow | |
| 4119 simulate_overflow = true; | |
| 4120 } | |
| 4121 ) | |
| 4122 if (simulate_overflow || | |
|
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4123 !(_work_queue->push(obj) || _overflow_stack->par_push(obj))) { |
| 0 | 4124 // stack overflow |
| 4125 if (PrintCMSStatistics != 0) { | |
| 4126 gclog_or_tty->print_cr("CMS marking stack overflow (benign) at " | |
| 4127 SIZE_FORMAT, _overflow_stack->capacity()); | |
| 4128 } | |
| 4129 // We cannot assert that the overflow stack is full because | |
| 4130 // it may have been emptied since. | |
| 4131 assert(simulate_overflow || | |
| 4132 _work_queue->size() == _work_queue->max_elems(), | |
| 4133 "Else push should have succeeded"); | |
| 4134 handle_stack_overflow(addr); | |
| 4135 } | |
| 4136 } // Else, some other thread got there first | |
|
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4137 do_yield_check(); |
| 0 | 4138 } |
| 4139 } | |
| 4140 | |
|
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4141 void Par_ConcMarkingClosure::do_oop(oop* p) { Par_ConcMarkingClosure::do_oop_work(p); } |
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4142 void Par_ConcMarkingClosure::do_oop(narrowOop* p) { Par_ConcMarkingClosure::do_oop_work(p); } |
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4143 |
| 0 | 4144 void Par_ConcMarkingClosure::trim_queue(size_t max) { |
| 4145 while (_work_queue->size() > max) { | |
| 4146 oop new_oop; | |
| 4147 if (_work_queue->pop_local(new_oop)) { | |
| 4148 assert(new_oop->is_oop(), "Should be an oop"); | |
| 4149 assert(_bit_map->isMarked((HeapWord*)new_oop), "Grey object"); | |
| 4150 assert(_span.contains((HeapWord*)new_oop), "Not in span"); | |
| 4151 new_oop->oop_iterate(this); // do_oop() above | |
|
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4152 do_yield_check(); |
| 0 | 4153 } |
| 4154 } | |
| 4155 } | |
| 4156 | |
| 4157 // Upon stack overflow, we discard (part of) the stack, | |
| 4158 // remembering the least address amongst those discarded | |
| 4159 // in CMSCollector's _restart_address. | |
| 4160 void Par_ConcMarkingClosure::handle_stack_overflow(HeapWord* lost) { | |
| 4161 // We need to do this under a mutex to prevent other | |
|
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4162 // workers from interfering with the work done below. |
| 0 | 4163 MutexLockerEx ml(_overflow_stack->par_lock(), |
| 4164 Mutex::_no_safepoint_check_flag); | |
| 4165 // Remember the least grey address discarded | |
| 4166 HeapWord* ra = (HeapWord*)_overflow_stack->least_value(lost); | |
| 4167 _collector->lower_restart_addr(ra); | |
| 4168 _overflow_stack->reset(); // discard stack contents | |
| 4169 _overflow_stack->expand(); // expand the stack if possible | |
| 4170 } | |
| 4171 | |
| 4172 | |
| 4173 void CMSConcMarkingTask::do_work_steal(int i) { | |
| 4174 OopTaskQueue* work_q = work_queue(i); | |
| 4175 oop obj_to_scan; | |
| 4176 CMSBitMap* bm = &(_collector->_markBitMap); | |
| 4177 CMSMarkStack* ovflw = &(_collector->_markStack); | |
| 4178 int* seed = _collector->hash_seed(i); | |
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4179 Par_ConcMarkingClosure cl(_collector, this, work_q, bm, ovflw); |
| 0 | 4180 while (true) { |
| 4181 cl.trim_queue(0); | |
| 4182 assert(work_q->size() == 0, "Should have been emptied above"); | |
| 4183 if (get_work_from_overflow_stack(ovflw, work_q)) { | |
| 4184 // Can't assert below because the work obtained from the | |
| 4185 // overflow stack may already have been stolen from us. | |
| 4186 // assert(work_q->size() > 0, "Work from overflow stack"); | |
| 4187 continue; | |
| 4188 } else if (task_queues()->steal(i, seed, /* reference */ obj_to_scan)) { | |
| 4189 assert(obj_to_scan->is_oop(), "Should be an oop"); | |
| 4190 assert(bm->isMarked((HeapWord*)obj_to_scan), "Grey object"); | |
| 4191 obj_to_scan->oop_iterate(&cl); | |
|
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4192 } else if (terminator()->offer_termination(&_term_term)) { |
| 0 | 4193 assert(work_q->size() == 0, "Impossible!"); |
| 4194 break; | |
|
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4195 } else if (yielding() || should_yield()) { |
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4196 yield(); |
| 0 | 4197 } |
| 4198 } | |
| 4199 } | |
| 4200 | |
| 4201 // This is run by the CMS (coordinator) thread. | |
| 4202 void CMSConcMarkingTask::coordinator_yield() { | |
| 4203 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 4204 "CMS thread should hold CMS token"); | |
| 4205 // First give up the locks, then yield, then re-lock | |
| 4206 // We should probably use a constructor/destructor idiom to | |
| 4207 // do this unlock/lock or modify the MutexUnlocker class to | |
| 4208 // serve our purpose. XXX | |
| 4209 assert_lock_strong(_bit_map_lock); | |
| 4210 _bit_map_lock->unlock(); | |
| 4211 ConcurrentMarkSweepThread::desynchronize(true); | |
| 4212 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 4213 _collector->stopTimer(); | |
| 4214 if (PrintCMSStatistics != 0) { | |
| 4215 _collector->incrementYields(); | |
| 4216 } | |
| 4217 _collector->icms_wait(); | |
| 4218 | |
| 4219 // It is possible for whichever thread initiated the yield request | |
| 4220 // not to get a chance to wake up and take the bitmap lock between | |
| 4221 // this thread releasing it and reacquiring it. So, while the | |
| 4222 // should_yield() flag is on, let's sleep for a bit to give the | |
| 4223 // other thread a chance to wake up. The limit imposed on the number | |
| 4224 // of iterations is defensive, to avoid any unforseen circumstances | |
| 4225 // putting us into an infinite loop. Since it's always been this | |
| 4226 // (coordinator_yield()) method that was observed to cause the | |
| 4227 // problem, we are using a parameter (CMSCoordinatorYieldSleepCount) | |
| 4228 // which is by default non-zero. For the other seven methods that | |
| 4229 // also perform the yield operation, as are using a different | |
| 4230 // parameter (CMSYieldSleepCount) which is by default zero. This way we | |
| 4231 // can enable the sleeping for those methods too, if necessary. | |
| 4232 // See 6442774. | |
| 4233 // | |
| 4234 // We really need to reconsider the synchronization between the GC | |
| 4235 // thread and the yield-requesting threads in the future and we | |
| 4236 // should really use wait/notify, which is the recommended | |
| 4237 // way of doing this type of interaction. Additionally, we should | |
| 4238 // consolidate the eight methods that do the yield operation and they | |
| 4239 // are almost identical into one for better maintenability and | |
| 4240 // readability. See 6445193. | |
| 4241 // | |
| 4242 // Tony 2006.06.29 | |
| 4243 for (unsigned i = 0; i < CMSCoordinatorYieldSleepCount && | |
|
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4244 ConcurrentMarkSweepThread::should_yield() && |
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4245 !CMSCollector::foregroundGCIsActive(); ++i) { |
| 0 | 4246 os::sleep(Thread::current(), 1, false); |
| 4247 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 4248 } | |
| 4249 | |
| 4250 ConcurrentMarkSweepThread::synchronize(true); | |
| 4251 _bit_map_lock->lock_without_safepoint_check(); | |
| 4252 _collector->startTimer(); | |
| 4253 } | |
| 4254 | |
| 4255 bool CMSCollector::do_marking_mt(bool asynch) { | |
| 1284 | 4256 assert(ConcGCThreads > 0 && conc_workers() != NULL, "precondition"); |
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4257 int num_workers = AdaptiveSizePolicy::calc_active_conc_workers( |
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4258 conc_workers()->total_workers(), |
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4259 conc_workers()->active_workers(), |
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4260 Threads::number_of_non_daemon_threads()); |
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4261 conc_workers()->set_active_workers(num_workers); |
| 0 | 4262 |
| 4263 CompactibleFreeListSpace* cms_space = _cmsGen->cmsSpace(); | |
| 4264 | |
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4265 CMSConcMarkingTask tsk(this, |
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4266 cms_space, |
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4267 asynch, |
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4268 conc_workers(), |
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4269 task_queues()); |
| 0 | 4270 |
| 4271 // Since the actual number of workers we get may be different | |
| 4272 // from the number we requested above, do we need to do anything different | |
| 4273 // below? In particular, may be we need to subclass the SequantialSubTasksDone | |
| 4274 // class?? XXX | |
| 4275 cms_space ->initialize_sequential_subtasks_for_marking(num_workers); | |
| 4276 | |
| 4277 // Refs discovery is already non-atomic. | |
| 4278 assert(!ref_processor()->discovery_is_atomic(), "Should be non-atomic"); | |
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4279 assert(ref_processor()->discovery_is_mt(), "Discovery should be MT"); |
| 0 | 4280 conc_workers()->start_task(&tsk); |
| 4281 while (tsk.yielded()) { | |
| 4282 tsk.coordinator_yield(); | |
| 4283 conc_workers()->continue_task(&tsk); | |
| 4284 } | |
| 4285 // If the task was aborted, _restart_addr will be non-NULL | |
| 4286 assert(tsk.completed() || _restart_addr != NULL, "Inconsistency"); | |
| 4287 while (_restart_addr != NULL) { | |
| 4288 // XXX For now we do not make use of ABORTED state and have not | |
| 4289 // yet implemented the right abort semantics (even in the original | |
| 4290 // single-threaded CMS case). That needs some more investigation | |
| 4291 // and is deferred for now; see CR# TBF. 07252005YSR. XXX | |
| 4292 assert(!CMSAbortSemantics || tsk.aborted(), "Inconsistency"); | |
| 4293 // If _restart_addr is non-NULL, a marking stack overflow | |
| 605 | 4294 // occurred; we need to do a fresh marking iteration from the |
| 0 | 4295 // indicated restart address. |
| 4296 if (_foregroundGCIsActive && asynch) { | |
| 4297 // We may be running into repeated stack overflows, having | |
| 4298 // reached the limit of the stack size, while making very | |
| 4299 // slow forward progress. It may be best to bail out and | |
| 4300 // let the foreground collector do its job. | |
| 4301 // Clear _restart_addr, so that foreground GC | |
| 4302 // works from scratch. This avoids the headache of | |
| 4303 // a "rescan" which would otherwise be needed because | |
| 4304 // of the dirty mod union table & card table. | |
| 4305 _restart_addr = NULL; | |
| 4306 return false; | |
| 4307 } | |
| 4308 // Adjust the task to restart from _restart_addr | |
| 4309 tsk.reset(_restart_addr); | |
| 4310 cms_space ->initialize_sequential_subtasks_for_marking(num_workers, | |
| 4311 _restart_addr); | |
| 4312 _restart_addr = NULL; | |
| 4313 // Get the workers going again | |
| 4314 conc_workers()->start_task(&tsk); | |
| 4315 while (tsk.yielded()) { | |
| 4316 tsk.coordinator_yield(); | |
| 4317 conc_workers()->continue_task(&tsk); | |
| 4318 } | |
| 4319 } | |
| 4320 assert(tsk.completed(), "Inconsistency"); | |
| 4321 assert(tsk.result() == true, "Inconsistency"); | |
| 4322 return true; | |
| 4323 } | |
| 4324 | |
| 4325 bool CMSCollector::do_marking_st(bool asynch) { | |
| 4326 ResourceMark rm; | |
| 4327 HandleMark hm; | |
| 4328 | |
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4329 // Temporarily make refs discovery single threaded (non-MT) |
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4330 ReferenceProcessorMTDiscoveryMutator rp_mut_discovery(ref_processor(), false); |
| 0 | 4331 MarkFromRootsClosure markFromRootsClosure(this, _span, &_markBitMap, |
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4332 &_markStack, CMSYield && asynch); |
| 0 | 4333 // the last argument to iterate indicates whether the iteration |
| 4334 // should be incremental with periodic yields. | |
| 4335 _markBitMap.iterate(&markFromRootsClosure); | |
| 4336 // If _restart_addr is non-NULL, a marking stack overflow | |
| 605 | 4337 // occurred; we need to do a fresh iteration from the |
| 0 | 4338 // indicated restart address. |
| 4339 while (_restart_addr != NULL) { | |
| 4340 if (_foregroundGCIsActive && asynch) { | |
| 4341 // We may be running into repeated stack overflows, having | |
| 4342 // reached the limit of the stack size, while making very | |
| 4343 // slow forward progress. It may be best to bail out and | |
| 4344 // let the foreground collector do its job. | |
| 4345 // Clear _restart_addr, so that foreground GC | |
| 4346 // works from scratch. This avoids the headache of | |
| 4347 // a "rescan" which would otherwise be needed because | |
| 4348 // of the dirty mod union table & card table. | |
| 4349 _restart_addr = NULL; | |
| 4350 return false; // indicating failure to complete marking | |
| 4351 } | |
| 4352 // Deal with stack overflow: | |
| 4353 // we restart marking from _restart_addr | |
| 4354 HeapWord* ra = _restart_addr; | |
| 4355 markFromRootsClosure.reset(ra); | |
| 4356 _restart_addr = NULL; | |
| 4357 _markBitMap.iterate(&markFromRootsClosure, ra, _span.end()); | |
| 4358 } | |
| 4359 return true; | |
| 4360 } | |
| 4361 | |
| 4362 void CMSCollector::preclean() { | |
| 4363 check_correct_thread_executing(); | |
| 4364 assert(Thread::current()->is_ConcurrentGC_thread(), "Wrong thread"); | |
| 4365 verify_work_stacks_empty(); | |
| 4366 verify_overflow_empty(); | |
| 4367 _abort_preclean = false; | |
| 4368 if (CMSPrecleaningEnabled) { | |
| 4369 _eden_chunk_index = 0; | |
| 4370 size_t used = get_eden_used(); | |
| 4371 size_t capacity = get_eden_capacity(); | |
| 4372 // Don't start sampling unless we will get sufficiently | |
| 4373 // many samples. | |
| 4374 if (used < (capacity/(CMSScheduleRemarkSamplingRatio * 100) | |
| 4375 * CMSScheduleRemarkEdenPenetration)) { | |
| 4376 _start_sampling = true; | |
| 4377 } else { | |
| 4378 _start_sampling = false; | |
| 4379 } | |
| 4380 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
| 4381 CMSPhaseAccounting pa(this, "preclean", !PrintGCDetails); | |
| 4382 preclean_work(CMSPrecleanRefLists1, CMSPrecleanSurvivors1); | |
| 4383 } | |
| 4384 CMSTokenSync x(true); // is cms thread | |
| 4385 if (CMSPrecleaningEnabled) { | |
| 4386 sample_eden(); | |
| 4387 _collectorState = AbortablePreclean; | |
| 4388 } else { | |
| 4389 _collectorState = FinalMarking; | |
| 4390 } | |
| 4391 verify_work_stacks_empty(); | |
| 4392 verify_overflow_empty(); | |
| 4393 } | |
| 4394 | |
| 4395 // Try and schedule the remark such that young gen | |
| 4396 // occupancy is CMSScheduleRemarkEdenPenetration %. | |
| 4397 void CMSCollector::abortable_preclean() { | |
| 4398 check_correct_thread_executing(); | |
| 4399 assert(CMSPrecleaningEnabled, "Inconsistent control state"); | |
| 4400 assert(_collectorState == AbortablePreclean, "Inconsistent control state"); | |
| 4401 | |
| 4402 // If Eden's current occupancy is below this threshold, | |
| 4403 // immediately schedule the remark; else preclean | |
| 4404 // past the next scavenge in an effort to | |
| 4405 // schedule the pause as described avove. By choosing | |
| 4406 // CMSScheduleRemarkEdenSizeThreshold >= max eden size | |
| 4407 // we will never do an actual abortable preclean cycle. | |
| 4408 if (get_eden_used() > CMSScheduleRemarkEdenSizeThreshold) { | |
| 4409 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
| 4410 CMSPhaseAccounting pa(this, "abortable-preclean", !PrintGCDetails); | |
| 4411 // We need more smarts in the abortable preclean | |
| 4412 // loop below to deal with cases where allocation | |
| 4413 // in young gen is very very slow, and our precleaning | |
| 4414 // is running a losing race against a horde of | |
| 4415 // mutators intent on flooding us with CMS updates | |
| 4416 // (dirty cards). | |
| 4417 // One, admittedly dumb, strategy is to give up | |
| 4418 // after a certain number of abortable precleaning loops | |
| 4419 // or after a certain maximum time. We want to make | |
| 4420 // this smarter in the next iteration. | |
| 4421 // XXX FIX ME!!! YSR | |
| 4422 size_t loops = 0, workdone = 0, cumworkdone = 0, waited = 0; | |
| 4423 while (!(should_abort_preclean() || | |
| 4424 ConcurrentMarkSweepThread::should_terminate())) { | |
| 4425 workdone = preclean_work(CMSPrecleanRefLists2, CMSPrecleanSurvivors2); | |
| 4426 cumworkdone += workdone; | |
| 4427 loops++; | |
| 4428 // Voluntarily terminate abortable preclean phase if we have | |
| 4429 // been at it for too long. | |
| 4430 if ((CMSMaxAbortablePrecleanLoops != 0) && | |
| 4431 loops >= CMSMaxAbortablePrecleanLoops) { | |
| 4432 if (PrintGCDetails) { | |
| 4433 gclog_or_tty->print(" CMS: abort preclean due to loops "); | |
| 4434 } | |
| 4435 break; | |
| 4436 } | |
| 4437 if (pa.wallclock_millis() > CMSMaxAbortablePrecleanTime) { | |
| 4438 if (PrintGCDetails) { | |
| 4439 gclog_or_tty->print(" CMS: abort preclean due to time "); | |
| 4440 } | |
| 4441 break; | |
| 4442 } | |
| 4443 // If we are doing little work each iteration, we should | |
| 4444 // take a short break. | |
| 4445 if (workdone < CMSAbortablePrecleanMinWorkPerIteration) { | |
| 4446 // Sleep for some time, waiting for work to accumulate | |
| 4447 stopTimer(); | |
| 4448 cmsThread()->wait_on_cms_lock(CMSAbortablePrecleanWaitMillis); | |
| 4449 startTimer(); | |
| 4450 waited++; | |
| 4451 } | |
| 4452 } | |
| 4453 if (PrintCMSStatistics > 0) { | |
| 4454 gclog_or_tty->print(" [%d iterations, %d waits, %d cards)] ", | |
| 4455 loops, waited, cumworkdone); | |
| 4456 } | |
| 4457 } | |
| 4458 CMSTokenSync x(true); // is cms thread | |
| 4459 if (_collectorState != Idling) { | |
| 4460 assert(_collectorState == AbortablePreclean, | |
| 4461 "Spontaneous state transition?"); | |
| 4462 _collectorState = FinalMarking; | |
| 4463 } // Else, a foreground collection completed this CMS cycle. | |
| 4464 return; | |
| 4465 } | |
| 4466 | |
| 4467 // Respond to an Eden sampling opportunity | |
| 4468 void CMSCollector::sample_eden() { | |
| 4469 // Make sure a young gc cannot sneak in between our | |
| 4470 // reading and recording of a sample. | |
| 4471 assert(Thread::current()->is_ConcurrentGC_thread(), | |
| 4472 "Only the cms thread may collect Eden samples"); | |
| 4473 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 4474 "Should collect samples while holding CMS token"); | |
| 4475 if (!_start_sampling) { | |
| 4476 return; | |
| 4477 } | |
| 4478 if (_eden_chunk_array) { | |
| 4479 if (_eden_chunk_index < _eden_chunk_capacity) { | |
| 4480 _eden_chunk_array[_eden_chunk_index] = *_top_addr; // take sample | |
| 4481 assert(_eden_chunk_array[_eden_chunk_index] <= *_end_addr, | |
| 4482 "Unexpected state of Eden"); | |
| 4483 // We'd like to check that what we just sampled is an oop-start address; | |
| 4484 // however, we cannot do that here since the object may not yet have been | |
| 4485 // initialized. So we'll instead do the check when we _use_ this sample | |
| 4486 // later. | |
| 4487 if (_eden_chunk_index == 0 || | |
| 4488 (pointer_delta(_eden_chunk_array[_eden_chunk_index], | |
| 4489 _eden_chunk_array[_eden_chunk_index-1]) | |
| 4490 >= CMSSamplingGrain)) { | |
| 4491 _eden_chunk_index++; // commit sample | |
| 4492 } | |
| 4493 } | |
| 4494 } | |
| 4495 if ((_collectorState == AbortablePreclean) && !_abort_preclean) { | |
| 4496 size_t used = get_eden_used(); | |
| 4497 size_t capacity = get_eden_capacity(); | |
| 4498 assert(used <= capacity, "Unexpected state of Eden"); | |
| 4499 if (used > (capacity/100 * CMSScheduleRemarkEdenPenetration)) { | |
| 4500 _abort_preclean = true; | |
| 4501 } | |
| 4502 } | |
| 4503 } | |
| 4504 | |
| 4505 | |
| 4506 size_t CMSCollector::preclean_work(bool clean_refs, bool clean_survivor) { | |
| 4507 assert(_collectorState == Precleaning || | |
| 4508 _collectorState == AbortablePreclean, "incorrect state"); | |
| 4509 ResourceMark rm; | |
| 4510 HandleMark hm; | |
|
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4511 |
|
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4512 // Precleaning is currently not MT but the reference processor |
|
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|
4513 // may be set for MT. Disable it temporarily here. |
|
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4514 ReferenceProcessor* rp = ref_processor(); |
|
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|
4515 ReferenceProcessorMTDiscoveryMutator rp_mut_discovery(rp, false); |
|
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|
4516 |
| 0 | 4517 // Do one pass of scrubbing the discovered reference lists |
| 4518 // to remove any reference objects with strongly-reachable | |
| 4519 // referents. | |
| 4520 if (clean_refs) { | |
| 4521 CMSPrecleanRefsYieldClosure yield_cl(this); | |
| 4522 assert(rp->span().equals(_span), "Spans should be equal"); | |
| 4523 CMSKeepAliveClosure keep_alive(this, _span, &_markBitMap, | |
|
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4524 &_markStack, true /* preclean */); |
| 0 | 4525 CMSDrainMarkingStackClosure complete_trace(this, |
|
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4526 _span, &_markBitMap, &_markStack, |
|
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|
4527 &keep_alive, true /* preclean */); |
| 0 | 4528 |
| 4529 // We don't want this step to interfere with a young | |
| 4530 // collection because we don't want to take CPU | |
| 4531 // or memory bandwidth away from the young GC threads | |
| 4532 // (which may be as many as there are CPUs). | |
| 4533 // Note that we don't need to protect ourselves from | |
| 4534 // interference with mutators because they can't | |
| 4535 // manipulate the discovered reference lists nor affect | |
| 4536 // the computed reachability of the referents, the | |
| 4537 // only properties manipulated by the precleaning | |
| 4538 // of these reference lists. | |
| 4539 stopTimer(); | |
| 4540 CMSTokenSyncWithLocks x(true /* is cms thread */, | |
| 4541 bitMapLock()); | |
| 4542 startTimer(); | |
| 4543 sample_eden(); | |
| 935 | 4544 |
| 0 | 4545 // The following will yield to allow foreground |
| 4546 // collection to proceed promptly. XXX YSR: | |
| 4547 // The code in this method may need further | |
| 4548 // tweaking for better performance and some restructuring | |
| 4549 // for cleaner interfaces. | |
| 4550 rp->preclean_discovered_references( | |
|
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|
4551 rp->is_alive_non_header(), &keep_alive, &complete_trace, &yield_cl); |
| 0 | 4552 } |
| 4553 | |
| 4554 if (clean_survivor) { // preclean the active survivor space(s) | |
| 4555 assert(_young_gen->kind() == Generation::DefNew || | |
| 4556 _young_gen->kind() == Generation::ParNew || | |
| 4557 _young_gen->kind() == Generation::ASParNew, | |
| 4558 "incorrect type for cast"); | |
| 4559 DefNewGeneration* dng = (DefNewGeneration*)_young_gen; | |
| 4560 PushAndMarkClosure pam_cl(this, _span, ref_processor(), | |
| 4561 &_markBitMap, &_modUnionTable, | |
|
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|
4562 &_markStack, true /* precleaning phase */); |
| 0 | 4563 stopTimer(); |
| 4564 CMSTokenSyncWithLocks ts(true /* is cms thread */, | |
| 4565 bitMapLock()); | |
| 4566 startTimer(); | |
| 4567 unsigned int before_count = | |
| 4568 GenCollectedHeap::heap()->total_collections(); | |
| 4569 SurvivorSpacePrecleanClosure | |
| 4570 sss_cl(this, _span, &_markBitMap, &_markStack, | |
| 4571 &pam_cl, before_count, CMSYield); | |
| 4572 dng->from()->object_iterate_careful(&sss_cl); | |
| 4573 dng->to()->object_iterate_careful(&sss_cl); | |
| 4574 } | |
| 4575 MarkRefsIntoAndScanClosure | |
| 4576 mrias_cl(_span, ref_processor(), &_markBitMap, &_modUnionTable, | |
|
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|
4577 &_markStack, this, CMSYield, |
| 0 | 4578 true /* precleaning phase */); |
| 4579 // CAUTION: The following closure has persistent state that may need to | |
| 4580 // be reset upon a decrease in the sequence of addresses it | |
| 4581 // processes. | |
| 4582 ScanMarkedObjectsAgainCarefullyClosure | |
| 4583 smoac_cl(this, _span, | |
|
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|
4584 &_markBitMap, &_markStack, &mrias_cl, CMSYield); |
| 0 | 4585 |
| 4586 // Preclean dirty cards in ModUnionTable and CardTable using | |
| 4587 // appropriate convergence criterion; | |
| 4588 // repeat CMSPrecleanIter times unless we find that | |
| 4589 // we are losing. | |
| 4590 assert(CMSPrecleanIter < 10, "CMSPrecleanIter is too large"); | |
| 4591 assert(CMSPrecleanNumerator < CMSPrecleanDenominator, | |
| 4592 "Bad convergence multiplier"); | |
| 4593 assert(CMSPrecleanThreshold >= 100, | |
| 4594 "Unreasonably low CMSPrecleanThreshold"); | |
| 4595 | |
| 4596 size_t numIter, cumNumCards, lastNumCards, curNumCards; | |
| 4597 for (numIter = 0, cumNumCards = lastNumCards = curNumCards = 0; | |
| 4598 numIter < CMSPrecleanIter; | |
| 4599 numIter++, lastNumCards = curNumCards, cumNumCards += curNumCards) { | |
| 4600 curNumCards = preclean_mod_union_table(_cmsGen, &smoac_cl); | |
| 4601 if (Verbose && PrintGCDetails) { | |
| 4602 gclog_or_tty->print(" (modUnionTable: %d cards)", curNumCards); | |
| 4603 } | |
| 4604 // Either there are very few dirty cards, so re-mark | |
| 4605 // pause will be small anyway, or our pre-cleaning isn't | |
| 4606 // that much faster than the rate at which cards are being | |
| 4607 // dirtied, so we might as well stop and re-mark since | |
| 4608 // precleaning won't improve our re-mark time by much. | |
| 4609 if (curNumCards <= CMSPrecleanThreshold || | |
| 4610 (numIter > 0 && | |
| 4611 (curNumCards * CMSPrecleanDenominator > | |
| 4612 lastNumCards * CMSPrecleanNumerator))) { | |
| 4613 numIter++; | |
| 4614 cumNumCards += curNumCards; | |
| 4615 break; | |
| 4616 } | |
| 4617 } | |
|
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|
4618 |
|
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|
4619 preclean_klasses(&mrias_cl, _cmsGen->freelistLock()); |
|
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|
4620 |
| 0 | 4621 curNumCards = preclean_card_table(_cmsGen, &smoac_cl); |
| 4622 cumNumCards += curNumCards; | |
| 4623 if (PrintGCDetails && PrintCMSStatistics != 0) { | |
| 4624 gclog_or_tty->print_cr(" (cardTable: %d cards, re-scanned %d cards, %d iterations)", | |
| 4625 curNumCards, cumNumCards, numIter); | |
| 4626 } | |
| 4627 return cumNumCards; // as a measure of useful work done | |
| 4628 } | |
| 4629 | |
| 4630 // PRECLEANING NOTES: | |
| 4631 // Precleaning involves: | |
| 4632 // . reading the bits of the modUnionTable and clearing the set bits. | |
| 4633 // . For the cards corresponding to the set bits, we scan the | |
| 4634 // objects on those cards. This means we need the free_list_lock | |
| 4635 // so that we can safely iterate over the CMS space when scanning | |
| 4636 // for oops. | |
| 4637 // . When we scan the objects, we'll be both reading and setting | |
| 4638 // marks in the marking bit map, so we'll need the marking bit map. | |
| 4639 // . For protecting _collector_state transitions, we take the CGC_lock. | |
| 4640 // Note that any races in the reading of of card table entries by the | |
| 4641 // CMS thread on the one hand and the clearing of those entries by the | |
| 4642 // VM thread or the setting of those entries by the mutator threads on the | |
| 4643 // other are quite benign. However, for efficiency it makes sense to keep | |
| 4644 // the VM thread from racing with the CMS thread while the latter is | |
| 4645 // dirty card info to the modUnionTable. We therefore also use the | |
| 4646 // CGC_lock to protect the reading of the card table and the mod union | |
| 4647 // table by the CM thread. | |
| 4648 // . We run concurrently with mutator updates, so scanning | |
| 4649 // needs to be done carefully -- we should not try to scan | |
| 4650 // potentially uninitialized objects. | |
| 4651 // | |
| 4652 // Locking strategy: While holding the CGC_lock, we scan over and | |
| 4653 // reset a maximal dirty range of the mod union / card tables, then lock | |
| 4654 // the free_list_lock and bitmap lock to do a full marking, then | |
| 4655 // release these locks; and repeat the cycle. This allows for a | |
| 4656 // certain amount of fairness in the sharing of these locks between | |
| 4657 // the CMS collector on the one hand, and the VM thread and the | |
| 4658 // mutators on the other. | |
| 4659 | |
| 4660 // NOTE: preclean_mod_union_table() and preclean_card_table() | |
| 4661 // further below are largely identical; if you need to modify | |
| 4662 // one of these methods, please check the other method too. | |
| 4663 | |
| 4664 size_t CMSCollector::preclean_mod_union_table( | |
| 4665 ConcurrentMarkSweepGeneration* gen, | |
| 4666 ScanMarkedObjectsAgainCarefullyClosure* cl) { | |
| 4667 verify_work_stacks_empty(); | |
| 4668 verify_overflow_empty(); | |
| 4669 | |
| 4670 // strategy: starting with the first card, accumulate contiguous | |
| 4671 // ranges of dirty cards; clear these cards, then scan the region | |
| 4672 // covered by these cards. | |
| 4673 | |
| 4674 // Since all of the MUT is committed ahead, we can just use | |
| 4675 // that, in case the generations expand while we are precleaning. | |
| 4676 // It might also be fine to just use the committed part of the | |
| 4677 // generation, but we might potentially miss cards when the | |
| 4678 // generation is rapidly expanding while we are in the midst | |
| 4679 // of precleaning. | |
| 4680 HeapWord* startAddr = gen->reserved().start(); | |
| 4681 HeapWord* endAddr = gen->reserved().end(); | |
| 4682 | |
| 4683 cl->setFreelistLock(gen->freelistLock()); // needed for yielding | |
| 4684 | |
| 4685 size_t numDirtyCards, cumNumDirtyCards; | |
| 4686 HeapWord *nextAddr, *lastAddr; | |
| 4687 for (cumNumDirtyCards = numDirtyCards = 0, | |
| 4688 nextAddr = lastAddr = startAddr; | |
| 4689 nextAddr < endAddr; | |
| 4690 nextAddr = lastAddr, cumNumDirtyCards += numDirtyCards) { | |
| 4691 | |
| 4692 ResourceMark rm; | |
| 4693 HandleMark hm; | |
| 4694 | |
| 4695 MemRegion dirtyRegion; | |
| 4696 { | |
| 4697 stopTimer(); | |
| 935 | 4698 // Potential yield point |
| 0 | 4699 CMSTokenSync ts(true); |
| 4700 startTimer(); | |
| 4701 sample_eden(); | |
| 4702 // Get dirty region starting at nextOffset (inclusive), | |
| 4703 // simultaneously clearing it. | |
| 4704 dirtyRegion = | |
| 4705 _modUnionTable.getAndClearMarkedRegion(nextAddr, endAddr); | |
| 4706 assert(dirtyRegion.start() >= nextAddr, | |
| 4707 "returned region inconsistent?"); | |
| 4708 } | |
| 4709 // Remember where the next search should begin. | |
| 4710 // The returned region (if non-empty) is a right open interval, | |
| 4711 // so lastOffset is obtained from the right end of that | |
| 4712 // interval. | |
| 4713 lastAddr = dirtyRegion.end(); | |
| 4714 // Should do something more transparent and less hacky XXX | |
| 4715 numDirtyCards = | |
| 4716 _modUnionTable.heapWordDiffToOffsetDiff(dirtyRegion.word_size()); | |
| 4717 | |
| 4718 // We'll scan the cards in the dirty region (with periodic | |
| 4719 // yields for foreground GC as needed). | |
| 4720 if (!dirtyRegion.is_empty()) { | |
| 4721 assert(numDirtyCards > 0, "consistency check"); | |
| 4722 HeapWord* stop_point = NULL; | |
|
453
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|
4723 stopTimer(); |
| 935 | 4724 // Potential yield point |
|
453
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|
4725 CMSTokenSyncWithLocks ts(true, gen->freelistLock(), |
|
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diff
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|
4726 bitMapLock()); |
|
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|
4727 startTimer(); |
| 0 | 4728 { |
| 4729 verify_work_stacks_empty(); | |
| 4730 verify_overflow_empty(); | |
| 4731 sample_eden(); | |
| 4732 stop_point = | |
| 4733 gen->cmsSpace()->object_iterate_careful_m(dirtyRegion, cl); | |
| 4734 } | |
| 4735 if (stop_point != NULL) { | |
| 4736 // The careful iteration stopped early either because it found an | |
| 4737 // uninitialized object, or because we were in the midst of an | |
| 4738 // "abortable preclean", which should now be aborted. Redirty | |
| 4739 // the bits corresponding to the partially-scanned or unscanned | |
| 4740 // cards. We'll either restart at the next block boundary or | |
| 4741 // abort the preclean. | |
|
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4742 assert((_collectorState == AbortablePreclean && should_abort_preclean()), |
|
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|
4743 "Should only be AbortablePreclean."); |
| 0 | 4744 _modUnionTable.mark_range(MemRegion(stop_point, dirtyRegion.end())); |
| 4745 if (should_abort_preclean()) { | |
| 4746 break; // out of preclean loop | |
| 4747 } else { | |
| 4748 // Compute the next address at which preclean should pick up; | |
| 4749 // might need bitMapLock in order to read P-bits. | |
| 4750 lastAddr = next_card_start_after_block(stop_point); | |
| 4751 } | |
| 4752 } | |
| 4753 } else { | |
| 4754 assert(lastAddr == endAddr, "consistency check"); | |
| 4755 assert(numDirtyCards == 0, "consistency check"); | |
| 4756 break; | |
| 4757 } | |
| 4758 } | |
| 4759 verify_work_stacks_empty(); | |
| 4760 verify_overflow_empty(); | |
| 4761 return cumNumDirtyCards; | |
| 4762 } | |
| 4763 | |
| 4764 // NOTE: preclean_mod_union_table() above and preclean_card_table() | |
| 4765 // below are largely identical; if you need to modify | |
| 4766 // one of these methods, please check the other method too. | |
| 4767 | |
| 4768 size_t CMSCollector::preclean_card_table(ConcurrentMarkSweepGeneration* gen, | |
| 4769 ScanMarkedObjectsAgainCarefullyClosure* cl) { | |
| 4770 // strategy: it's similar to precleamModUnionTable above, in that | |
| 4771 // we accumulate contiguous ranges of dirty cards, mark these cards | |
| 4772 // precleaned, then scan the region covered by these cards. | |
| 4773 HeapWord* endAddr = (HeapWord*)(gen->_virtual_space.high()); | |
| 4774 HeapWord* startAddr = (HeapWord*)(gen->_virtual_space.low()); | |
| 4775 | |
| 4776 cl->setFreelistLock(gen->freelistLock()); // needed for yielding | |
| 4777 | |
| 4778 size_t numDirtyCards, cumNumDirtyCards; | |
| 4779 HeapWord *lastAddr, *nextAddr; | |
| 4780 | |
| 4781 for (cumNumDirtyCards = numDirtyCards = 0, | |
| 4782 nextAddr = lastAddr = startAddr; | |
| 4783 nextAddr < endAddr; | |
| 4784 nextAddr = lastAddr, cumNumDirtyCards += numDirtyCards) { | |
| 4785 | |
| 4786 ResourceMark rm; | |
| 4787 HandleMark hm; | |
| 4788 | |
| 4789 MemRegion dirtyRegion; | |
| 4790 { | |
| 4791 // See comments in "Precleaning notes" above on why we | |
| 4792 // do this locking. XXX Could the locking overheads be | |
| 4793 // too high when dirty cards are sparse? [I don't think so.] | |
| 4794 stopTimer(); | |
| 4795 CMSTokenSync x(true); // is cms thread | |
| 4796 startTimer(); | |
| 4797 sample_eden(); | |
| 4798 // Get and clear dirty region from card table | |
|
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4799 dirtyRegion = _ct->ct_bs()->dirty_card_range_after_reset( |
|
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4800 MemRegion(nextAddr, endAddr), |
|
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|
4801 true, |
|
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|
4802 CardTableModRefBS::precleaned_card_val()); |
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4803 |
| 0 | 4804 assert(dirtyRegion.start() >= nextAddr, |
| 4805 "returned region inconsistent?"); | |
| 4806 } | |
| 4807 lastAddr = dirtyRegion.end(); | |
| 4808 numDirtyCards = | |
| 4809 dirtyRegion.word_size()/CardTableModRefBS::card_size_in_words; | |
| 4810 | |
| 4811 if (!dirtyRegion.is_empty()) { | |
| 4812 stopTimer(); | |
| 4813 CMSTokenSyncWithLocks ts(true, gen->freelistLock(), bitMapLock()); | |
| 4814 startTimer(); | |
| 4815 sample_eden(); | |
| 4816 verify_work_stacks_empty(); | |
| 4817 verify_overflow_empty(); | |
| 4818 HeapWord* stop_point = | |
| 4819 gen->cmsSpace()->object_iterate_careful_m(dirtyRegion, cl); | |
| 4820 if (stop_point != NULL) { | |
|
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4821 assert((_collectorState == AbortablePreclean && should_abort_preclean()), |
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4822 "Should only be AbortablePreclean."); |
| 0 | 4823 _ct->ct_bs()->invalidate(MemRegion(stop_point, dirtyRegion.end())); |
| 4824 if (should_abort_preclean()) { | |
| 4825 break; // out of preclean loop | |
| 4826 } else { | |
| 4827 // Compute the next address at which preclean should pick up. | |
| 4828 lastAddr = next_card_start_after_block(stop_point); | |
| 4829 } | |
| 4830 } | |
| 4831 } else { | |
| 4832 break; | |
| 4833 } | |
| 4834 } | |
| 4835 verify_work_stacks_empty(); | |
| 4836 verify_overflow_empty(); | |
| 4837 return cumNumDirtyCards; | |
| 4838 } | |
| 4839 | |
|
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4840 class PrecleanKlassClosure : public KlassClosure { |
|
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4841 CMKlassClosure _cm_klass_closure; |
|
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4842 public: |
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4843 PrecleanKlassClosure(OopClosure* oop_closure) : _cm_klass_closure(oop_closure) {} |
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4844 void do_klass(Klass* k) { |
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4845 if (k->has_accumulated_modified_oops()) { |
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4846 k->clear_accumulated_modified_oops(); |
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4847 |
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4848 _cm_klass_closure.do_klass(k); |
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4849 } |
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4850 } |
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4851 }; |
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4852 |
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4853 // The freelist lock is needed to prevent asserts, is it really needed? |
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4854 void CMSCollector::preclean_klasses(MarkRefsIntoAndScanClosure* cl, Mutex* freelistLock) { |
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4855 |
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4856 cl->set_freelistLock(freelistLock); |
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4857 |
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4858 CMSTokenSyncWithLocks ts(true, freelistLock, bitMapLock()); |
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4859 |
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4860 // SSS: Add equivalent to ScanMarkedObjectsAgainCarefullyClosure::do_yield_check and should_abort_preclean? |
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4861 // SSS: We should probably check if precleaning should be aborted, at suitable intervals? |
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4862 PrecleanKlassClosure preclean_klass_closure(cl); |
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4863 ClassLoaderDataGraph::classes_do(&preclean_klass_closure); |
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4864 |
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4865 verify_work_stacks_empty(); |
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4866 verify_overflow_empty(); |
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4867 } |
|
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4868 |
| 0 | 4869 void CMSCollector::checkpointRootsFinal(bool asynch, |
| 4870 bool clear_all_soft_refs, bool init_mark_was_synchronous) { | |
| 4871 assert(_collectorState == FinalMarking, "incorrect state transition?"); | |
| 4872 check_correct_thread_executing(); | |
| 4873 // world is stopped at this checkpoint | |
| 4874 assert(SafepointSynchronize::is_at_safepoint(), | |
| 4875 "world should be stopped"); | |
|
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4876 TraceCMSMemoryManagerStats tms(_collectorState,GenCollectedHeap::heap()->gc_cause()); |
|
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4877 |
| 0 | 4878 verify_work_stacks_empty(); |
| 4879 verify_overflow_empty(); | |
| 4880 | |
| 4881 SpecializationStats::clear(); | |
| 4882 if (PrintGCDetails) { | |
| 4883 gclog_or_tty->print("[YG occupancy: "SIZE_FORMAT" K ("SIZE_FORMAT" K)]", | |
| 4884 _young_gen->used() / K, | |
| 4885 _young_gen->capacity() / K); | |
| 4886 } | |
| 4887 if (asynch) { | |
| 4888 if (CMSScavengeBeforeRemark) { | |
| 4889 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 4890 // Temporarily set flag to false, GCH->do_collection will | |
| 4891 // expect it to be false and set to true | |
| 4892 FlagSetting fl(gch->_is_gc_active, false); | |
| 4893 NOT_PRODUCT(TraceTime t("Scavenge-Before-Remark", | |
| 4894 PrintGCDetails && Verbose, true, gclog_or_tty);) | |
| 4895 int level = _cmsGen->level() - 1; | |
| 4896 if (level >= 0) { | |
| 4897 gch->do_collection(true, // full (i.e. force, see below) | |
| 4898 false, // !clear_all_soft_refs | |
| 4899 0, // size | |
| 4900 false, // is_tlab | |
| 4901 level // max_level | |
| 4902 ); | |
| 4903 } | |
| 4904 } | |
| 4905 FreelistLocker x(this); | |
| 4906 MutexLockerEx y(bitMapLock(), | |
| 4907 Mutex::_no_safepoint_check_flag); | |
| 4908 assert(!init_mark_was_synchronous, "but that's impossible!"); | |
| 4909 checkpointRootsFinalWork(asynch, clear_all_soft_refs, false); | |
| 4910 } else { | |
| 4911 // already have all the locks | |
| 4912 checkpointRootsFinalWork(asynch, clear_all_soft_refs, | |
| 4913 init_mark_was_synchronous); | |
| 4914 } | |
| 4915 verify_work_stacks_empty(); | |
| 4916 verify_overflow_empty(); | |
| 4917 SpecializationStats::print(); | |
| 4918 } | |
| 4919 | |
| 4920 void CMSCollector::checkpointRootsFinalWork(bool asynch, | |
| 4921 bool clear_all_soft_refs, bool init_mark_was_synchronous) { | |
| 4922 | |
| 4923 NOT_PRODUCT(TraceTime tr("checkpointRootsFinalWork", PrintGCDetails, false, gclog_or_tty);) | |
| 4924 | |
| 4925 assert(haveFreelistLocks(), "must have free list locks"); | |
| 4926 assert_lock_strong(bitMapLock()); | |
| 4927 | |
| 4928 if (UseAdaptiveSizePolicy) { | |
| 4929 size_policy()->checkpoint_roots_final_begin(); | |
| 4930 } | |
| 4931 | |
| 4932 ResourceMark rm; | |
| 4933 HandleMark hm; | |
| 4934 | |
| 4935 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 4936 | |
|
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|
4937 if (should_unload_classes()) { |
| 0 | 4938 CodeCache::gc_prologue(); |
| 4939 } | |
| 4940 assert(haveFreelistLocks(), "must have free list locks"); | |
| 4941 assert_lock_strong(bitMapLock()); | |
| 4942 | |
| 4943 if (!init_mark_was_synchronous) { | |
| 4944 // We might assume that we need not fill TLAB's when | |
| 4945 // CMSScavengeBeforeRemark is set, because we may have just done | |
| 4946 // a scavenge which would have filled all TLAB's -- and besides | |
| 4947 // Eden would be empty. This however may not always be the case -- | |
| 4948 // for instance although we asked for a scavenge, it may not have | |
| 4949 // happened because of a JNI critical section. We probably need | |
| 4950 // a policy for deciding whether we can in that case wait until | |
| 4951 // the critical section releases and then do the remark following | |
| 4952 // the scavenge, and skip it here. In the absence of that policy, | |
| 4953 // or of an indication of whether the scavenge did indeed occur, | |
| 4954 // we cannot rely on TLAB's having been filled and must do | |
| 4955 // so here just in case a scavenge did not happen. | |
| 4956 gch->ensure_parsability(false); // fill TLAB's, but no need to retire them | |
| 4957 // Update the saved marks which may affect the root scans. | |
| 4958 gch->save_marks(); | |
| 4959 | |
| 4960 { | |
| 4961 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact;) | |
| 4962 | |
| 4963 // Note on the role of the mod union table: | |
| 4964 // Since the marker in "markFromRoots" marks concurrently with | |
| 4965 // mutators, it is possible for some reachable objects not to have been | |
| 4966 // scanned. For instance, an only reference to an object A was | |
| 4967 // placed in object B after the marker scanned B. Unless B is rescanned, | |
| 4968 // A would be collected. Such updates to references in marked objects | |
| 4969 // are detected via the mod union table which is the set of all cards | |
| 4970 // dirtied since the first checkpoint in this GC cycle and prior to | |
| 4971 // the most recent young generation GC, minus those cleaned up by the | |
| 4972 // concurrent precleaning. | |
|
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4973 if (CMSParallelRemarkEnabled && CollectedHeap::use_parallel_gc_threads()) { |
| 0 | 4974 TraceTime t("Rescan (parallel) ", PrintGCDetails, false, gclog_or_tty); |
| 4975 do_remark_parallel(); | |
| 4976 } else { | |
| 4977 TraceTime t("Rescan (non-parallel) ", PrintGCDetails, false, | |
| 4978 gclog_or_tty); | |
| 4979 do_remark_non_parallel(); | |
| 4980 } | |
| 4981 } | |
| 4982 } else { | |
| 4983 assert(!asynch, "Can't have init_mark_was_synchronous in asynch mode"); | |
| 4984 // The initial mark was stop-world, so there's no rescanning to | |
| 4985 // do; go straight on to the next step below. | |
| 4986 } | |
| 4987 verify_work_stacks_empty(); | |
| 4988 verify_overflow_empty(); | |
| 4989 | |
| 4990 { | |
| 4991 NOT_PRODUCT(TraceTime ts("refProcessingWork", PrintGCDetails, false, gclog_or_tty);) | |
| 4992 refProcessingWork(asynch, clear_all_soft_refs); | |
| 4993 } | |
| 4994 verify_work_stacks_empty(); | |
| 4995 verify_overflow_empty(); | |
| 4996 | |
|
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4997 if (should_unload_classes()) { |
| 0 | 4998 CodeCache::gc_epilogue(); |
| 4999 } | |
|
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|
5000 JvmtiExport::gc_epilogue(); |
| 0 | 5001 |
| 5002 // If we encountered any (marking stack / work queue) overflow | |
| 5003 // events during the current CMS cycle, take appropriate | |
| 5004 // remedial measures, where possible, so as to try and avoid | |
| 5005 // recurrence of that condition. | |
| 5006 assert(_markStack.isEmpty(), "No grey objects"); | |
| 5007 size_t ser_ovflw = _ser_pmc_remark_ovflw + _ser_pmc_preclean_ovflw + | |
|
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|
5008 _ser_kac_ovflw + _ser_kac_preclean_ovflw; |
| 0 | 5009 if (ser_ovflw > 0) { |
| 5010 if (PrintCMSStatistics != 0) { | |
| 5011 gclog_or_tty->print_cr("Marking stack overflow (benign) " | |
|
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5012 "(pmc_pc="SIZE_FORMAT", pmc_rm="SIZE_FORMAT", kac="SIZE_FORMAT |
|
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|
5013 ", kac_preclean="SIZE_FORMAT")", |
| 0 | 5014 _ser_pmc_preclean_ovflw, _ser_pmc_remark_ovflw, |
|
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|
5015 _ser_kac_ovflw, _ser_kac_preclean_ovflw); |
| 0 | 5016 } |
| 5017 _markStack.expand(); | |
| 5018 _ser_pmc_remark_ovflw = 0; | |
| 5019 _ser_pmc_preclean_ovflw = 0; | |
|
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|
5020 _ser_kac_preclean_ovflw = 0; |
| 0 | 5021 _ser_kac_ovflw = 0; |
| 5022 } | |
| 5023 if (_par_pmc_remark_ovflw > 0 || _par_kac_ovflw > 0) { | |
| 5024 if (PrintCMSStatistics != 0) { | |
| 5025 gclog_or_tty->print_cr("Work queue overflow (benign) " | |
| 5026 "(pmc_rm="SIZE_FORMAT", kac="SIZE_FORMAT")", | |
| 5027 _par_pmc_remark_ovflw, _par_kac_ovflw); | |
| 5028 } | |
| 5029 _par_pmc_remark_ovflw = 0; | |
| 5030 _par_kac_ovflw = 0; | |
| 5031 } | |
| 5032 if (PrintCMSStatistics != 0) { | |
| 5033 if (_markStack._hit_limit > 0) { | |
| 5034 gclog_or_tty->print_cr(" (benign) Hit max stack size limit ("SIZE_FORMAT")", | |
| 5035 _markStack._hit_limit); | |
| 5036 } | |
| 5037 if (_markStack._failed_double > 0) { | |
| 5038 gclog_or_tty->print_cr(" (benign) Failed stack doubling ("SIZE_FORMAT")," | |
| 5039 " current capacity "SIZE_FORMAT, | |
| 5040 _markStack._failed_double, | |
| 5041 _markStack.capacity()); | |
| 5042 } | |
| 5043 } | |
| 5044 _markStack._hit_limit = 0; | |
| 5045 _markStack._failed_double = 0; | |
| 5046 | |
| 5047 if ((VerifyAfterGC || VerifyDuringGC) && | |
| 5048 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
| 5049 verify_after_remark(); | |
| 5050 } | |
| 5051 | |
| 5052 // Change under the freelistLocks. | |
| 5053 _collectorState = Sweeping; | |
| 5054 // Call isAllClear() under bitMapLock | |
|
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5055 assert(_modUnionTable.isAllClear(), |
|
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5056 "Should be clear by end of the final marking"); |
|
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5057 assert(_ct->klass_rem_set()->mod_union_is_clear(), |
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5058 "Should be clear by end of the final marking"); |
| 0 | 5059 if (UseAdaptiveSizePolicy) { |
| 5060 size_policy()->checkpoint_roots_final_end(gch->gc_cause()); | |
| 5061 } | |
| 5062 } | |
| 5063 | |
| 5064 // Parallel remark task | |
| 5065 class CMSParRemarkTask: public AbstractGangTask { | |
| 5066 CMSCollector* _collector; | |
| 5067 int _n_workers; | |
| 5068 CompactibleFreeListSpace* _cms_space; | |
| 5069 | |
| 5070 // The per-thread work queues, available here for stealing. | |
| 5071 OopTaskQueueSet* _task_queues; | |
| 5072 ParallelTaskTerminator _term; | |
| 5073 | |
| 5074 public: | |
|
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|
5075 // A value of 0 passed to n_workers will cause the number of |
|
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|
5076 // workers to be taken from the active workers in the work gang. |
| 0 | 5077 CMSParRemarkTask(CMSCollector* collector, |
| 5078 CompactibleFreeListSpace* cms_space, | |
|
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|
5079 int n_workers, FlexibleWorkGang* workers, |
| 0 | 5080 OopTaskQueueSet* task_queues): |
| 5081 AbstractGangTask("Rescan roots and grey objects in parallel"), | |
| 5082 _collector(collector), | |
|
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5083 _cms_space(cms_space), |
| 0 | 5084 _n_workers(n_workers), |
| 5085 _task_queues(task_queues), | |
|
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|
5086 _term(n_workers, task_queues) { } |
| 0 | 5087 |
| 5088 OopTaskQueueSet* task_queues() { return _task_queues; } | |
| 5089 | |
| 5090 OopTaskQueue* work_queue(int i) { return task_queues()->queue(i); } | |
| 5091 | |
| 5092 ParallelTaskTerminator* terminator() { return &_term; } | |
|
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|
5093 int n_workers() { return _n_workers; } |
| 0 | 5094 |
|
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|
5095 void work(uint worker_id); |
| 0 | 5096 |
| 5097 private: | |
| 5098 // Work method in support of parallel rescan ... of young gen spaces | |
| 5099 void do_young_space_rescan(int i, Par_MarkRefsIntoAndScanClosure* cl, | |
| 5100 ContiguousSpace* space, | |
| 5101 HeapWord** chunk_array, size_t chunk_top); | |
| 5102 | |
| 5103 // ... of dirty cards in old space | |
| 5104 void do_dirty_card_rescan_tasks(CompactibleFreeListSpace* sp, int i, | |
| 5105 Par_MarkRefsIntoAndScanClosure* cl); | |
| 5106 | |
| 5107 // ... work stealing for the above | |
| 5108 void do_work_steal(int i, Par_MarkRefsIntoAndScanClosure* cl, int* seed); | |
| 5109 }; | |
| 5110 | |
|
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5111 class RemarkKlassClosure : public KlassClosure { |
|
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5112 CMKlassClosure _cm_klass_closure; |
|
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5113 public: |
|
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5114 RemarkKlassClosure(OopClosure* oop_closure) : _cm_klass_closure(oop_closure) {} |
|
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5115 void do_klass(Klass* k) { |
|
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5116 // Check if we have modified any oops in the Klass during the concurrent marking. |
|
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5117 if (k->has_accumulated_modified_oops()) { |
|
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5118 k->clear_accumulated_modified_oops(); |
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5119 |
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5120 // We could have transfered the current modified marks to the accumulated marks, |
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5121 // like we do with the Card Table to Mod Union Table. But it's not really necessary. |
|
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5122 } else if (k->has_modified_oops()) { |
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5123 // Don't clear anything, this info is needed by the next young collection. |
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5124 } else { |
|
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5125 // No modified oops in the Klass. |
|
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5126 return; |
|
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5127 } |
|
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5128 |
|
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5129 // The klass has modified fields, need to scan the klass. |
|
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5130 _cm_klass_closure.do_klass(k); |
|
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5131 } |
|
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5132 }; |
|
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5133 |
|
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5134 // work_queue(i) is passed to the closure |
|
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5135 // Par_MarkRefsIntoAndScanClosure. The "i" parameter |
|
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5136 // also is passed to do_dirty_card_rescan_tasks() and to |
|
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5137 // do_work_steal() to select the i-th task_queue. |
|
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5138 |
|
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|
5139 void CMSParRemarkTask::work(uint worker_id) { |
| 0 | 5140 elapsedTimer _timer; |
| 5141 ResourceMark rm; | |
| 5142 HandleMark hm; | |
| 5143 | |
| 5144 // ---------- rescan from roots -------------- | |
| 5145 _timer.start(); | |
| 5146 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 5147 Par_MarkRefsIntoAndScanClosure par_mrias_cl(_collector, | |
| 5148 _collector->_span, _collector->ref_processor(), | |
| 5149 &(_collector->_markBitMap), | |
|
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5150 work_queue(worker_id)); |
| 0 | 5151 |
| 5152 // Rescan young gen roots first since these are likely | |
| 5153 // coarsely partitioned and may, on that account, constitute | |
| 5154 // the critical path; thus, it's best to start off that | |
| 5155 // work first. | |
| 5156 // ---------- young gen roots -------------- | |
| 5157 { | |
| 5158 DefNewGeneration* dng = _collector->_young_gen->as_DefNewGeneration(); | |
| 5159 EdenSpace* eden_space = dng->eden(); | |
| 5160 ContiguousSpace* from_space = dng->from(); | |
| 5161 ContiguousSpace* to_space = dng->to(); | |
| 5162 | |
| 5163 HeapWord** eca = _collector->_eden_chunk_array; | |
| 5164 size_t ect = _collector->_eden_chunk_index; | |
| 5165 HeapWord** sca = _collector->_survivor_chunk_array; | |
| 5166 size_t sct = _collector->_survivor_chunk_index; | |
| 5167 | |
| 5168 assert(ect <= _collector->_eden_chunk_capacity, "out of bounds"); | |
| 5169 assert(sct <= _collector->_survivor_chunk_capacity, "out of bounds"); | |
| 5170 | |
|
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|
5171 do_young_space_rescan(worker_id, &par_mrias_cl, to_space, NULL, 0); |
|
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5172 do_young_space_rescan(worker_id, &par_mrias_cl, from_space, sca, sct); |
|
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|
5173 do_young_space_rescan(worker_id, &par_mrias_cl, eden_space, eca, ect); |
| 0 | 5174 |
| 5175 _timer.stop(); | |
| 5176 if (PrintCMSStatistics != 0) { | |
| 5177 gclog_or_tty->print_cr( | |
| 5178 "Finished young gen rescan work in %dth thread: %3.3f sec", | |
|
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|
5179 worker_id, _timer.seconds()); |
| 0 | 5180 } |
| 5181 } | |
| 5182 | |
| 5183 // ---------- remaining roots -------------- | |
| 5184 _timer.reset(); | |
| 5185 _timer.start(); | |
| 5186 gch->gen_process_strong_roots(_collector->_cmsGen->level(), | |
| 5187 false, // yg was scanned above | |
|
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|
5188 false, // this is parallel code |
|
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5189 false, // not scavenging |
| 0 | 5190 SharedHeap::ScanningOption(_collector->CMSCollector::roots_scanning_options()), |
|
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|
5191 &par_mrias_cl, |
|
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|
5192 true, // walk all of code cache if (so & SO_CodeCache) |
|
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5193 NULL, |
|
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|
5194 NULL); // The dirty klasses will be handled below |
|
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|
5195 assert(_collector->should_unload_classes() |
|
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|
5196 || (_collector->CMSCollector::roots_scanning_options() & SharedHeap::SO_CodeCache), |
|
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|
5197 "if we didn't scan the code cache, we have to be ready to drop nmethods with expired weak oops"); |
| 0 | 5198 _timer.stop(); |
| 5199 if (PrintCMSStatistics != 0) { | |
| 5200 gclog_or_tty->print_cr( | |
| 5201 "Finished remaining root rescan work in %dth thread: %3.3f sec", | |
|
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|
5202 worker_id, _timer.seconds()); |
| 0 | 5203 } |
| 5204 | |
|
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5205 // ---------- unhandled CLD scanning ---------- |
|
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|
5206 if (worker_id == 0) { // Single threaded at the moment. |
|
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|
5207 _timer.reset(); |
|
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|
5208 _timer.start(); |
|
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|
5209 |
|
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|
5210 // Scan all new class loader data objects and new dependencies that were |
|
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|
5211 // introduced during concurrent marking. |
|
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|
5212 ResourceMark rm; |
|
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|
5213 GrowableArray<ClassLoaderData*>* array = ClassLoaderDataGraph::new_clds(); |
|
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|
5214 for (int i = 0; i < array->length(); i++) { |
|
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|
5215 par_mrias_cl.do_class_loader_data(array->at(i)); |
|
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|
5216 } |
|
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|
5217 |
|
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|
5218 // We don't need to keep track of new CLDs anymore. |
|
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|
5219 ClassLoaderDataGraph::remember_new_clds(false); |
|
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|
5220 |
|
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|
5221 _timer.stop(); |
|
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|
5222 if (PrintCMSStatistics != 0) { |
|
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|
5223 gclog_or_tty->print_cr( |
|
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5224 "Finished unhandled CLD scanning work in %dth thread: %3.3f sec", |
|
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|
5225 worker_id, _timer.seconds()); |
|
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|
5226 } |
|
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|
5227 } |
|
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|
5228 |
|
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|
5229 // ---------- dirty klass scanning ---------- |
|
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|
5230 if (worker_id == 0) { // Single threaded at the moment. |
|
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|
5231 _timer.reset(); |
|
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|
5232 _timer.start(); |
|
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|
5233 |
|
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|
5234 // Scan all classes that was dirtied during the concurrent marking phase. |
|
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|
5235 RemarkKlassClosure remark_klass_closure(&par_mrias_cl); |
|
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|
5236 ClassLoaderDataGraph::classes_do(&remark_klass_closure); |
|
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|
5237 |
|
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|
5238 _timer.stop(); |
|
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|
5239 if (PrintCMSStatistics != 0) { |
|
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|
5240 gclog_or_tty->print_cr( |
|
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|
5241 "Finished dirty klass scanning work in %dth thread: %3.3f sec", |
|
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|
5242 worker_id, _timer.seconds()); |
|
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|
5243 } |
|
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|
5244 } |
|
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|
5245 |
|
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|
5246 // We might have added oops to ClassLoaderData::_handles during the |
|
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|
5247 // concurrent marking phase. These oops point to newly allocated objects |
|
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|
5248 // that are guaranteed to be kept alive. Either by the direct allocation |
|
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|
5249 // code, or when the young collector processes the strong roots. Hence, |
|
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|
5250 // we don't have to revisit the _handles block during the remark phase. |
|
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|
5251 |
| 0 | 5252 // ---------- rescan dirty cards ------------ |
| 5253 _timer.reset(); | |
| 5254 _timer.start(); | |
| 5255 | |
| 5256 // Do the rescan tasks for each of the two spaces | |
|
6725
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|
5257 // (cms_space) in turn. |
|
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|
5258 // "worker_id" is passed to select the task_queue for "worker_id" |
|
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|
5259 do_dirty_card_rescan_tasks(_cms_space, worker_id, &par_mrias_cl); |
| 0 | 5260 _timer.stop(); |
| 5261 if (PrintCMSStatistics != 0) { | |
| 5262 gclog_or_tty->print_cr( | |
| 5263 "Finished dirty card rescan work in %dth thread: %3.3f sec", | |
|
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|
5264 worker_id, _timer.seconds()); |
| 0 | 5265 } |
| 5266 | |
| 5267 // ---------- steal work from other threads ... | |
| 5268 // ---------- ... and drain overflow list. | |
| 5269 _timer.reset(); | |
| 5270 _timer.start(); | |
|
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changeset
|
5271 do_work_steal(worker_id, &par_mrias_cl, _collector->hash_seed(worker_id)); |
| 0 | 5272 _timer.stop(); |
| 5273 if (PrintCMSStatistics != 0) { | |
| 5274 gclog_or_tty->print_cr( | |
| 5275 "Finished work stealing in %dth thread: %3.3f sec", | |
|
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|
5276 worker_id, _timer.seconds()); |
| 0 | 5277 } |
| 5278 } | |
| 5279 | |
|
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|
5280 // Note that parameter "i" is not used. |
| 0 | 5281 void |
| 5282 CMSParRemarkTask::do_young_space_rescan(int i, | |
| 5283 Par_MarkRefsIntoAndScanClosure* cl, ContiguousSpace* space, | |
| 5284 HeapWord** chunk_array, size_t chunk_top) { | |
| 5285 // Until all tasks completed: | |
| 5286 // . claim an unclaimed task | |
| 5287 // . compute region boundaries corresponding to task claimed | |
| 5288 // using chunk_array | |
| 5289 // . par_oop_iterate(cl) over that region | |
| 5290 | |
| 5291 ResourceMark rm; | |
| 5292 HandleMark hm; | |
| 5293 | |
| 5294 SequentialSubTasksDone* pst = space->par_seq_tasks(); | |
| 5295 assert(pst->valid(), "Uninitialized use?"); | |
| 5296 | |
|
4728
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5297 uint nth_task = 0; |
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5298 uint n_tasks = pst->n_tasks(); |
| 0 | 5299 |
| 5300 HeapWord *start, *end; | |
| 5301 while (!pst->is_task_claimed(/* reference */ nth_task)) { | |
| 5302 // We claimed task # nth_task; compute its boundaries. | |
| 5303 if (chunk_top == 0) { // no samples were taken | |
| 5304 assert(nth_task == 0 && n_tasks == 1, "Can have only 1 EdenSpace task"); | |
| 5305 start = space->bottom(); | |
| 5306 end = space->top(); | |
| 5307 } else if (nth_task == 0) { | |
| 5308 start = space->bottom(); | |
| 5309 end = chunk_array[nth_task]; | |
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5310 } else if (nth_task < (uint)chunk_top) { |
| 0 | 5311 assert(nth_task >= 1, "Control point invariant"); |
| 5312 start = chunk_array[nth_task - 1]; | |
| 5313 end = chunk_array[nth_task]; | |
| 5314 } else { | |
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5315 assert(nth_task == (uint)chunk_top, "Control point invariant"); |
| 0 | 5316 start = chunk_array[chunk_top - 1]; |
| 5317 end = space->top(); | |
| 5318 } | |
| 5319 MemRegion mr(start, end); | |
| 5320 // Verify that mr is in space | |
| 5321 assert(mr.is_empty() || space->used_region().contains(mr), | |
| 5322 "Should be in space"); | |
| 5323 // Verify that "start" is an object boundary | |
| 5324 assert(mr.is_empty() || oop(mr.start())->is_oop(), | |
| 5325 "Should be an oop"); | |
| 5326 space->par_oop_iterate(mr, cl); | |
| 5327 } | |
| 5328 pst->all_tasks_completed(); | |
| 5329 } | |
| 5330 | |
| 5331 void | |
| 5332 CMSParRemarkTask::do_dirty_card_rescan_tasks( | |
| 5333 CompactibleFreeListSpace* sp, int i, | |
| 5334 Par_MarkRefsIntoAndScanClosure* cl) { | |
| 5335 // Until all tasks completed: | |
| 5336 // . claim an unclaimed task | |
| 5337 // . compute region boundaries corresponding to task claimed | |
| 5338 // . transfer dirty bits ct->mut for that region | |
| 5339 // . apply rescanclosure to dirty mut bits for that region | |
| 5340 | |
| 5341 ResourceMark rm; | |
| 5342 HandleMark hm; | |
| 5343 | |
| 5344 OopTaskQueue* work_q = work_queue(i); | |
| 5345 ModUnionClosure modUnionClosure(&(_collector->_modUnionTable)); | |
| 5346 // CAUTION! CAUTION! CAUTION! CAUTION! CAUTION! CAUTION! CAUTION! | |
| 5347 // CAUTION: This closure has state that persists across calls to | |
| 5348 // the work method dirty_range_iterate_clear() in that it has | |
| 5349 // imbedded in it a (subtype of) UpwardsObjectClosure. The | |
| 5350 // use of that state in the imbedded UpwardsObjectClosure instance | |
| 5351 // assumes that the cards are always iterated (even if in parallel | |
| 5352 // by several threads) in monotonically increasing order per each | |
| 5353 // thread. This is true of the implementation below which picks | |
| 5354 // card ranges (chunks) in monotonically increasing order globally | |
| 5355 // and, a-fortiori, in monotonically increasing order per thread | |
| 5356 // (the latter order being a subsequence of the former). | |
| 5357 // If the work code below is ever reorganized into a more chaotic | |
| 5358 // work-partitioning form than the current "sequential tasks" | |
| 5359 // paradigm, the use of that persistent state will have to be | |
| 5360 // revisited and modified appropriately. See also related | |
| 5361 // bug 4756801 work on which should examine this code to make | |
| 5362 // sure that the changes there do not run counter to the | |
| 5363 // assumptions made here and necessary for correctness and | |
| 5364 // efficiency. Note also that this code might yield inefficient | |
| 5365 // behaviour in the case of very large objects that span one or | |
| 5366 // more work chunks. Such objects would potentially be scanned | |
| 5367 // several times redundantly. Work on 4756801 should try and | |
| 5368 // address that performance anomaly if at all possible. XXX | |
| 5369 MemRegion full_span = _collector->_span; | |
| 5370 CMSBitMap* bm = &(_collector->_markBitMap); // shared | |
| 5371 MarkFromDirtyCardsClosure | |
| 5372 greyRescanClosure(_collector, full_span, // entire span of interest | |
|
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5373 sp, bm, work_q, cl); |
| 0 | 5374 |
| 5375 SequentialSubTasksDone* pst = sp->conc_par_seq_tasks(); | |
| 5376 assert(pst->valid(), "Uninitialized use?"); | |
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5377 uint nth_task = 0; |
| 0 | 5378 const int alignment = CardTableModRefBS::card_size * BitsPerWord; |
| 5379 MemRegion span = sp->used_region(); | |
| 5380 HeapWord* start_addr = span.start(); | |
| 5381 HeapWord* end_addr = (HeapWord*)round_to((intptr_t)span.end(), | |
| 5382 alignment); | |
| 5383 const size_t chunk_size = sp->rescan_task_size(); // in HeapWord units | |
| 5384 assert((HeapWord*)round_to((intptr_t)start_addr, alignment) == | |
| 5385 start_addr, "Check alignment"); | |
| 5386 assert((size_t)round_to((intptr_t)chunk_size, alignment) == | |
| 5387 chunk_size, "Check alignment"); | |
| 5388 | |
| 5389 while (!pst->is_task_claimed(/* reference */ nth_task)) { | |
| 5390 // Having claimed the nth_task, compute corresponding mem-region, | |
| 5391 // which is a-fortiori aligned correctly (i.e. at a MUT bopundary). | |
| 5392 // The alignment restriction ensures that we do not need any | |
| 5393 // synchronization with other gang-workers while setting or | |
| 5394 // clearing bits in thus chunk of the MUT. | |
| 5395 MemRegion this_span = MemRegion(start_addr + nth_task*chunk_size, | |
| 5396 start_addr + (nth_task+1)*chunk_size); | |
| 5397 // The last chunk's end might be way beyond end of the | |
| 5398 // used region. In that case pull back appropriately. | |
| 5399 if (this_span.end() > end_addr) { | |
| 5400 this_span.set_end(end_addr); | |
| 5401 assert(!this_span.is_empty(), "Program logic (calculation of n_tasks)"); | |
| 5402 } | |
| 5403 // Iterate over the dirty cards covering this chunk, marking them | |
| 5404 // precleaned, and setting the corresponding bits in the mod union | |
| 5405 // table. Since we have been careful to partition at Card and MUT-word | |
| 5406 // boundaries no synchronization is needed between parallel threads. | |
| 5407 _collector->_ct->ct_bs()->dirty_card_iterate(this_span, | |
| 5408 &modUnionClosure); | |
| 5409 | |
| 5410 // Having transferred these marks into the modUnionTable, | |
| 5411 // rescan the marked objects on the dirty cards in the modUnionTable. | |
| 5412 // Even if this is at a synchronous collection, the initial marking | |
| 5413 // may have been done during an asynchronous collection so there | |
| 5414 // may be dirty bits in the mod-union table. | |
| 5415 _collector->_modUnionTable.dirty_range_iterate_clear( | |
| 5416 this_span, &greyRescanClosure); | |
| 5417 _collector->_modUnionTable.verifyNoOneBitsInRange( | |
| 5418 this_span.start(), | |
| 5419 this_span.end()); | |
| 5420 } | |
| 5421 pst->all_tasks_completed(); // declare that i am done | |
| 5422 } | |
| 5423 | |
| 5424 // . see if we can share work_queues with ParNew? XXX | |
| 5425 void | |
| 5426 CMSParRemarkTask::do_work_steal(int i, Par_MarkRefsIntoAndScanClosure* cl, | |
| 5427 int* seed) { | |
| 5428 OopTaskQueue* work_q = work_queue(i); | |
| 5429 NOT_PRODUCT(int num_steals = 0;) | |
| 5430 oop obj_to_scan; | |
| 5431 CMSBitMap* bm = &(_collector->_markBitMap); | |
| 5432 | |
| 5433 while (true) { | |
| 5434 // Completely finish any left over work from (an) earlier round(s) | |
| 5435 cl->trim_queue(0); | |
|
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5436 size_t num_from_overflow_list = MIN2((size_t)(work_q->max_elems() - work_q->size())/4, |
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5437 (size_t)ParGCDesiredObjsFromOverflowList); |
| 0 | 5438 // Now check if there's any work in the overflow list |
|
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5439 // Passing ParallelGCThreads as the third parameter, no_of_gc_threads, |
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5440 // only affects the number of attempts made to get work from the |
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5441 // overflow list and does not affect the number of workers. Just |
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5442 // pass ParallelGCThreads so this behavior is unchanged. |
| 0 | 5443 if (_collector->par_take_from_overflow_list(num_from_overflow_list, |
|
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5444 work_q, |
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5445 ParallelGCThreads)) { |
| 0 | 5446 // found something in global overflow list; |
| 5447 // not yet ready to go stealing work from others. | |
| 5448 // We'd like to assert(work_q->size() != 0, ...) | |
| 5449 // because we just took work from the overflow list, | |
| 5450 // but of course we can't since all of that could have | |
| 5451 // been already stolen from us. | |
| 5452 // "He giveth and He taketh away." | |
| 5453 continue; | |
| 5454 } | |
| 5455 // Verify that we have no work before we resort to stealing | |
| 5456 assert(work_q->size() == 0, "Have work, shouldn't steal"); | |
| 5457 // Try to steal from other queues that have work | |
| 5458 if (task_queues()->steal(i, seed, /* reference */ obj_to_scan)) { | |
| 5459 NOT_PRODUCT(num_steals++;) | |
| 5460 assert(obj_to_scan->is_oop(), "Oops, not an oop!"); | |
| 5461 assert(bm->isMarked((HeapWord*)obj_to_scan), "Stole an unmarked oop?"); | |
| 5462 // Do scanning work | |
| 5463 obj_to_scan->oop_iterate(cl); | |
| 5464 // Loop around, finish this work, and try to steal some more | |
| 5465 } else if (terminator()->offer_termination()) { | |
| 5466 break; // nirvana from the infinite cycle | |
| 5467 } | |
| 5468 } | |
| 5469 NOT_PRODUCT( | |
| 5470 if (PrintCMSStatistics != 0) { | |
| 5471 gclog_or_tty->print("\n\t(%d: stole %d oops)", i, num_steals); | |
| 5472 } | |
| 5473 ) | |
| 5474 assert(work_q->size() == 0 && _collector->overflow_list_is_empty(), | |
| 5475 "Else our work is not yet done"); | |
| 5476 } | |
| 5477 | |
| 5478 // Return a thread-local PLAB recording array, as appropriate. | |
| 5479 void* CMSCollector::get_data_recorder(int thr_num) { | |
| 5480 if (_survivor_plab_array != NULL && | |
| 5481 (CMSPLABRecordAlways || | |
| 5482 (_collectorState > Marking && _collectorState < FinalMarking))) { | |
| 5483 assert(thr_num < (int)ParallelGCThreads, "thr_num is out of bounds"); | |
| 5484 ChunkArray* ca = &_survivor_plab_array[thr_num]; | |
| 5485 ca->reset(); // clear it so that fresh data is recorded | |
| 5486 return (void*) ca; | |
| 5487 } else { | |
| 5488 return NULL; | |
| 5489 } | |
| 5490 } | |
| 5491 | |
| 5492 // Reset all the thread-local PLAB recording arrays | |
| 5493 void CMSCollector::reset_survivor_plab_arrays() { | |
| 5494 for (uint i = 0; i < ParallelGCThreads; i++) { | |
| 5495 _survivor_plab_array[i].reset(); | |
| 5496 } | |
| 5497 } | |
| 5498 | |
| 5499 // Merge the per-thread plab arrays into the global survivor chunk | |
| 5500 // array which will provide the partitioning of the survivor space | |
| 5501 // for CMS rescan. | |
|
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5502 void CMSCollector::merge_survivor_plab_arrays(ContiguousSpace* surv, |
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5503 int no_of_gc_threads) { |
| 0 | 5504 assert(_survivor_plab_array != NULL, "Error"); |
| 5505 assert(_survivor_chunk_array != NULL, "Error"); | |
| 5506 assert(_collectorState == FinalMarking, "Error"); | |
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5507 for (int j = 0; j < no_of_gc_threads; j++) { |
| 0 | 5508 _cursor[j] = 0; |
| 5509 } | |
| 5510 HeapWord* top = surv->top(); | |
| 5511 size_t i; | |
| 5512 for (i = 0; i < _survivor_chunk_capacity; i++) { // all sca entries | |
| 5513 HeapWord* min_val = top; // Higher than any PLAB address | |
| 5514 uint min_tid = 0; // position of min_val this round | |
|
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5515 for (int j = 0; j < no_of_gc_threads; j++) { |
| 0 | 5516 ChunkArray* cur_sca = &_survivor_plab_array[j]; |
| 5517 if (_cursor[j] == cur_sca->end()) { | |
| 5518 continue; | |
| 5519 } | |
| 5520 assert(_cursor[j] < cur_sca->end(), "ctl pt invariant"); | |
| 5521 HeapWord* cur_val = cur_sca->nth(_cursor[j]); | |
| 5522 assert(surv->used_region().contains(cur_val), "Out of bounds value"); | |
| 5523 if (cur_val < min_val) { | |
| 5524 min_tid = j; | |
| 5525 min_val = cur_val; | |
| 5526 } else { | |
| 5527 assert(cur_val < top, "All recorded addresses should be less"); | |
| 5528 } | |
| 5529 } | |
| 5530 // At this point min_val and min_tid are respectively | |
| 5531 // the least address in _survivor_plab_array[j]->nth(_cursor[j]) | |
| 5532 // and the thread (j) that witnesses that address. | |
| 5533 // We record this address in the _survivor_chunk_array[i] | |
| 5534 // and increment _cursor[min_tid] prior to the next round i. | |
| 5535 if (min_val == top) { | |
| 5536 break; | |
| 5537 } | |
| 5538 _survivor_chunk_array[i] = min_val; | |
| 5539 _cursor[min_tid]++; | |
| 5540 } | |
| 5541 // We are all done; record the size of the _survivor_chunk_array | |
| 5542 _survivor_chunk_index = i; // exclusive: [0, i) | |
| 5543 if (PrintCMSStatistics > 0) { | |
| 5544 gclog_or_tty->print(" (Survivor:" SIZE_FORMAT "chunks) ", i); | |
| 5545 } | |
| 5546 // Verify that we used up all the recorded entries | |
| 5547 #ifdef ASSERT | |
| 5548 size_t total = 0; | |
|
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|
5549 for (int j = 0; j < no_of_gc_threads; j++) { |
| 0 | 5550 assert(_cursor[j] == _survivor_plab_array[j].end(), "Ctl pt invariant"); |
| 5551 total += _cursor[j]; | |
| 5552 } | |
| 5553 assert(total == _survivor_chunk_index, "Ctl Pt Invariant"); | |
| 5554 // Check that the merged array is in sorted order | |
| 5555 if (total > 0) { | |
| 5556 for (size_t i = 0; i < total - 1; i++) { | |
| 5557 if (PrintCMSStatistics > 0) { | |
| 5558 gclog_or_tty->print(" (chunk" SIZE_FORMAT ":" INTPTR_FORMAT ") ", | |
| 5559 i, _survivor_chunk_array[i]); | |
| 5560 } | |
| 5561 assert(_survivor_chunk_array[i] < _survivor_chunk_array[i+1], | |
| 5562 "Not sorted"); | |
| 5563 } | |
| 5564 } | |
| 5565 #endif // ASSERT | |
| 5566 } | |
| 5567 | |
| 5568 // Set up the space's par_seq_tasks structure for work claiming | |
| 5569 // for parallel rescan of young gen. | |
| 5570 // See ParRescanTask where this is currently used. | |
| 5571 void | |
| 5572 CMSCollector:: | |
| 5573 initialize_sequential_subtasks_for_young_gen_rescan(int n_threads) { | |
| 5574 assert(n_threads > 0, "Unexpected n_threads argument"); | |
| 5575 DefNewGeneration* dng = (DefNewGeneration*)_young_gen; | |
| 5576 | |
| 5577 // Eden space | |
| 5578 { | |
| 5579 SequentialSubTasksDone* pst = dng->eden()->par_seq_tasks(); | |
| 5580 assert(!pst->valid(), "Clobbering existing data?"); | |
| 5581 // Each valid entry in [0, _eden_chunk_index) represents a task. | |
| 5582 size_t n_tasks = _eden_chunk_index + 1; | |
| 5583 assert(n_tasks == 1 || _eden_chunk_array != NULL, "Error"); | |
|
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5584 // Sets the condition for completion of the subtask (how many threads |
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5585 // need to finish in order to be done). |
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5586 pst->set_n_threads(n_threads); |
| 0 | 5587 pst->set_n_tasks((int)n_tasks); |
| 5588 } | |
| 5589 | |
| 5590 // Merge the survivor plab arrays into _survivor_chunk_array | |
| 5591 if (_survivor_plab_array != NULL) { | |
|
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5592 merge_survivor_plab_arrays(dng->from(), n_threads); |
| 0 | 5593 } else { |
| 5594 assert(_survivor_chunk_index == 0, "Error"); | |
| 5595 } | |
| 5596 | |
| 5597 // To space | |
| 5598 { | |
| 5599 SequentialSubTasksDone* pst = dng->to()->par_seq_tasks(); | |
| 5600 assert(!pst->valid(), "Clobbering existing data?"); | |
|
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5601 // Sets the condition for completion of the subtask (how many threads |
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5602 // need to finish in order to be done). |
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5603 pst->set_n_threads(n_threads); |
| 0 | 5604 pst->set_n_tasks(1); |
| 5605 assert(pst->valid(), "Error"); | |
| 5606 } | |
| 5607 | |
| 5608 // From space | |
| 5609 { | |
| 5610 SequentialSubTasksDone* pst = dng->from()->par_seq_tasks(); | |
| 5611 assert(!pst->valid(), "Clobbering existing data?"); | |
| 5612 size_t n_tasks = _survivor_chunk_index + 1; | |
| 5613 assert(n_tasks == 1 || _survivor_chunk_array != NULL, "Error"); | |
|
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5614 // Sets the condition for completion of the subtask (how many threads |
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5615 // need to finish in order to be done). |
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5616 pst->set_n_threads(n_threads); |
| 0 | 5617 pst->set_n_tasks((int)n_tasks); |
| 5618 assert(pst->valid(), "Error"); | |
| 5619 } | |
| 5620 } | |
| 5621 | |
| 5622 // Parallel version of remark | |
| 5623 void CMSCollector::do_remark_parallel() { | |
| 5624 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
|
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5625 FlexibleWorkGang* workers = gch->workers(); |
| 0 | 5626 assert(workers != NULL, "Need parallel worker threads."); |
|
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5627 // Choose to use the number of GC workers most recently set |
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5628 // into "active_workers". If active_workers is not set, set it |
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5629 // to ParallelGCThreads. |
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5630 int n_workers = workers->active_workers(); |
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5631 if (n_workers == 0) { |
|
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5632 assert(n_workers > 0, "Should have been set during scavenge"); |
|
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5633 n_workers = ParallelGCThreads; |
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5634 workers->set_active_workers(n_workers); |
|
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|
5635 } |
| 0 | 5636 CompactibleFreeListSpace* cms_space = _cmsGen->cmsSpace(); |
| 5637 | |
| 5638 CMSParRemarkTask tsk(this, | |
|
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5639 cms_space, |
| 0 | 5640 n_workers, workers, task_queues()); |
| 5641 | |
| 5642 // Set up for parallel process_strong_roots work. | |
| 5643 gch->set_par_threads(n_workers); | |
| 5644 // We won't be iterating over the cards in the card table updating | |
| 5645 // the younger_gen cards, so we shouldn't call the following else | |
| 5646 // the verification code as well as subsequent younger_refs_iterate | |
| 5647 // code would get confused. XXX | |
| 5648 // gch->rem_set()->prepare_for_younger_refs_iterate(true); // parallel | |
| 5649 | |
| 5650 // The young gen rescan work will not be done as part of | |
| 5651 // process_strong_roots (which currently doesn't knw how to | |
| 5652 // parallelize such a scan), but rather will be broken up into | |
| 5653 // a set of parallel tasks (via the sampling that the [abortable] | |
| 5654 // preclean phase did of EdenSpace, plus the [two] tasks of | |
| 5655 // scanning the [two] survivor spaces. Further fine-grain | |
| 5656 // parallelization of the scanning of the survivor spaces | |
| 5657 // themselves, and of precleaning of the younger gen itself | |
| 5658 // is deferred to the future. | |
| 5659 initialize_sequential_subtasks_for_young_gen_rescan(n_workers); | |
| 5660 | |
| 5661 // The dirty card rescan work is broken up into a "sequence" | |
| 5662 // of parallel tasks (per constituent space) that are dynamically | |
| 5663 // claimed by the parallel threads. | |
| 5664 cms_space->initialize_sequential_subtasks_for_rescan(n_workers); | |
| 5665 | |
| 5666 // It turns out that even when we're using 1 thread, doing the work in a | |
| 5667 // separate thread causes wide variance in run times. We can't help this | |
| 5668 // in the multi-threaded case, but we special-case n=1 here to get | |
| 5669 // repeatable measurements of the 1-thread overhead of the parallel code. | |
| 5670 if (n_workers > 1) { | |
|
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|
5671 // Make refs discovery MT-safe, if it isn't already: it may not |
|
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|
5672 // necessarily be so, since it's possible that we are doing |
|
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|
5673 // ST marking. |
|
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|
5674 ReferenceProcessorMTDiscoveryMutator mt(ref_processor(), true); |
|
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|
5675 GenCollectedHeap::StrongRootsScope srs(gch); |
| 0 | 5676 workers->run_task(&tsk); |
| 5677 } else { | |
|
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|
5678 ReferenceProcessorMTDiscoveryMutator mt(ref_processor(), false); |
|
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|
5679 GenCollectedHeap::StrongRootsScope srs(gch); |
| 0 | 5680 tsk.work(0); |
| 5681 } | |
|
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5682 |
| 0 | 5683 gch->set_par_threads(0); // 0 ==> non-parallel. |
| 5684 // restore, single-threaded for now, any preserved marks | |
| 5685 // as a result of work_q overflow | |
| 5686 restore_preserved_marks_if_any(); | |
| 5687 } | |
| 5688 | |
| 5689 // Non-parallel version of remark | |
| 5690 void CMSCollector::do_remark_non_parallel() { | |
| 5691 ResourceMark rm; | |
| 5692 HandleMark hm; | |
| 5693 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
|
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|
5694 ReferenceProcessorMTDiscoveryMutator mt(ref_processor(), false); |
|
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|
5695 |
| 0 | 5696 MarkRefsIntoAndScanClosure |
|
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5697 mrias_cl(_span, ref_processor(), &_markBitMap, NULL /* not precleaning */, |
|
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|
5698 &_markStack, this, |
| 0 | 5699 false /* should_yield */, false /* not precleaning */); |
| 5700 MarkFromDirtyCardsClosure | |
| 5701 markFromDirtyCardsClosure(this, _span, | |
| 5702 NULL, // space is set further below | |
|
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|
5703 &_markBitMap, &_markStack, &mrias_cl); |
| 0 | 5704 { |
| 5705 TraceTime t("grey object rescan", PrintGCDetails, false, gclog_or_tty); | |
|
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|
5706 // Iterate over the dirty cards, setting the corresponding bits in the |
|
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|
5707 // mod union table. |
| 0 | 5708 { |
| 5709 ModUnionClosure modUnionClosure(&_modUnionTable); | |
| 5710 _ct->ct_bs()->dirty_card_iterate( | |
| 5711 _cmsGen->used_region(), | |
| 5712 &modUnionClosure); | |
| 5713 } | |
| 5714 // Having transferred these marks into the modUnionTable, we just need | |
| 5715 // to rescan the marked objects on the dirty cards in the modUnionTable. | |
| 5716 // The initial marking may have been done during an asynchronous | |
| 5717 // collection so there may be dirty bits in the mod-union table. | |
| 5718 const int alignment = | |
| 5719 CardTableModRefBS::card_size * BitsPerWord; | |
| 5720 { | |
| 5721 // ... First handle dirty cards in CMS gen | |
| 5722 markFromDirtyCardsClosure.set_space(_cmsGen->cmsSpace()); | |
| 5723 MemRegion ur = _cmsGen->used_region(); | |
| 5724 HeapWord* lb = ur.start(); | |
| 5725 HeapWord* ub = (HeapWord*)round_to((intptr_t)ur.end(), alignment); | |
| 5726 MemRegion cms_span(lb, ub); | |
| 5727 _modUnionTable.dirty_range_iterate_clear(cms_span, | |
| 5728 &markFromDirtyCardsClosure); | |
| 5729 verify_work_stacks_empty(); | |
| 5730 if (PrintCMSStatistics != 0) { | |
| 5731 gclog_or_tty->print(" (re-scanned "SIZE_FORMAT" dirty cards in cms gen) ", | |
| 5732 markFromDirtyCardsClosure.num_dirty_cards()); | |
| 5733 } | |
| 5734 } | |
| 5735 } | |
| 5736 if (VerifyDuringGC && | |
| 5737 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
| 5738 HandleMark hm; // Discard invalid handles created during verification | |
|
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changeset
|
5739 Universe::verify(); |
| 0 | 5740 } |
| 5741 { | |
| 5742 TraceTime t("root rescan", PrintGCDetails, false, gclog_or_tty); | |
| 5743 | |
| 5744 verify_work_stacks_empty(); | |
| 5745 | |
| 5746 gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel. | |
|
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|
5747 GenCollectedHeap::StrongRootsScope srs(gch); |
| 0 | 5748 gch->gen_process_strong_roots(_cmsGen->level(), |
| 5749 true, // younger gens as roots | |
|
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|
5750 false, // use the local StrongRootsScope |
|
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|
5751 false, // not scavenging |
| 0 | 5752 SharedHeap::ScanningOption(roots_scanning_options()), |
|
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|
5753 &mrias_cl, |
|
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|
5754 true, // walk code active on stacks |
|
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|
5755 NULL, |
|
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|
5756 NULL); // The dirty klasses will be handled below |
|
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|
5757 |
|
989
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|
5758 assert(should_unload_classes() |
|
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|
5759 || (roots_scanning_options() & SharedHeap::SO_CodeCache), |
|
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|
5760 "if we didn't scan the code cache, we have to be ready to drop nmethods with expired weak oops"); |
| 0 | 5761 } |
|
6725
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|
5762 |
|
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|
5763 { |
|
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|
5764 TraceTime t("visit unhandled CLDs", PrintGCDetails, false, gclog_or_tty); |
|
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|
5765 |
|
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|
5766 verify_work_stacks_empty(); |
|
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|
5767 |
|
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|
5768 // Scan all class loader data objects that might have been introduced |
|
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|
5769 // during concurrent marking. |
|
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|
5770 ResourceMark rm; |
|
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|
5771 GrowableArray<ClassLoaderData*>* array = ClassLoaderDataGraph::new_clds(); |
|
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|
5772 for (int i = 0; i < array->length(); i++) { |
|
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|
5773 mrias_cl.do_class_loader_data(array->at(i)); |
|
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|
5774 } |
|
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|
5775 |
|
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|
5776 // We don't need to keep track of new CLDs anymore. |
|
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|
5777 ClassLoaderDataGraph::remember_new_clds(false); |
|
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|
5778 |
|
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|
5779 verify_work_stacks_empty(); |
|
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|
5780 } |
|
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|
5781 |
|
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|
5782 { |
|
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|
5783 TraceTime t("dirty klass scan", PrintGCDetails, false, gclog_or_tty); |
|
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|
5784 |
|
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|
5785 verify_work_stacks_empty(); |
|
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|
5786 |
|
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|
5787 RemarkKlassClosure remark_klass_closure(&mrias_cl); |
|
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|
5788 ClassLoaderDataGraph::classes_do(&remark_klass_closure); |
|
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|
5789 |
|
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|
5790 verify_work_stacks_empty(); |
|
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|
5791 } |
|
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|
5792 |
|
da91efe96a93
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|
5793 // We might have added oops to ClassLoaderData::_handles during the |
|
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|
5794 // concurrent marking phase. These oops point to newly allocated objects |
|
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|
5795 // that are guaranteed to be kept alive. Either by the direct allocation |
|
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|
5796 // code, or when the young collector processes the strong roots. Hence, |
|
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|
5797 // we don't have to revisit the _handles block during the remark phase. |
|
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|
5798 |
| 0 | 5799 verify_work_stacks_empty(); |
| 5800 // Restore evacuated mark words, if any, used for overflow list links | |
| 5801 if (!CMSOverflowEarlyRestoration) { | |
| 5802 restore_preserved_marks_if_any(); | |
| 5803 } | |
| 5804 verify_overflow_empty(); | |
| 5805 } | |
| 5806 | |
| 5807 //////////////////////////////////////////////////////// | |
| 5808 // Parallel Reference Processing Task Proxy Class | |
| 5809 //////////////////////////////////////////////////////// | |
|
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|
5810 class CMSRefProcTaskProxy: public AbstractGangTaskWOopQueues { |
| 0 | 5811 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; |
| 5812 CMSCollector* _collector; | |
| 5813 CMSBitMap* _mark_bit_map; | |
|
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|
5814 const MemRegion _span; |
| 0 | 5815 ProcessTask& _task; |
| 5816 | |
| 5817 public: | |
| 5818 CMSRefProcTaskProxy(ProcessTask& task, | |
| 5819 CMSCollector* collector, | |
| 5820 const MemRegion& span, | |
| 5821 CMSBitMap* mark_bit_map, | |
|
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|
5822 AbstractWorkGang* workers, |
| 0 | 5823 OopTaskQueueSet* task_queues): |
|
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|
5824 // XXX Should superclass AGTWOQ also know about AWG since it knows |
|
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|
5825 // about the task_queues used by the AWG? Then it could initialize |
|
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|
5826 // the terminator() object. See 6984287. The set_for_termination() |
|
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|
5827 // below is a temporary band-aid for the regression in 6984287. |
|
1833
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|
5828 AbstractGangTaskWOopQueues("Process referents by policy in parallel", |
|
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|
5829 task_queues), |
| 0 | 5830 _task(task), |
|
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|
5831 _collector(collector), _span(span), _mark_bit_map(mark_bit_map) |
|
2369
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|
5832 { |
|
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|
5833 assert(_collector->_span.equals(_span) && !_span.is_empty(), |
|
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|
5834 "Inconsistency in _span"); |
|
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|
5835 set_for_termination(workers->active_workers()); |
|
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|
5836 } |
| 0 | 5837 |
|
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|
5838 OopTaskQueueSet* task_queues() { return queues(); } |
| 0 | 5839 |
| 5840 OopTaskQueue* work_queue(int i) { return task_queues()->queue(i); } | |
| 5841 | |
| 5842 void do_work_steal(int i, | |
| 5843 CMSParDrainMarkingStackClosure* drain, | |
| 5844 CMSParKeepAliveClosure* keep_alive, | |
| 5845 int* seed); | |
| 5846 | |
|
4728
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changeset
|
5847 virtual void work(uint worker_id); |
| 0 | 5848 }; |
| 5849 | |
|
4728
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|
5850 void CMSRefProcTaskProxy::work(uint worker_id) { |
|
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|
5851 assert(_collector->_span.equals(_span), "Inconsistency in _span"); |
| 0 | 5852 CMSParKeepAliveClosure par_keep_alive(_collector, _span, |
| 935 | 5853 _mark_bit_map, |
|
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7121618: Change type of number of GC workers to unsigned int.
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diff
changeset
|
5854 work_queue(worker_id)); |
| 0 | 5855 CMSParDrainMarkingStackClosure par_drain_stack(_collector, _span, |
| 935 | 5856 _mark_bit_map, |
|
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diff
changeset
|
5857 work_queue(worker_id)); |
|
143
b5489bb705c9
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113
diff
changeset
|
5858 CMSIsAliveClosure is_alive_closure(_span, _mark_bit_map); |
|
4728
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jmasa
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diff
changeset
|
5859 _task.work(worker_id, is_alive_closure, par_keep_alive, par_drain_stack); |
| 0 | 5860 if (_task.marks_oops_alive()) { |
|
4728
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jmasa
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4128
diff
changeset
|
5861 do_work_steal(worker_id, &par_drain_stack, &par_keep_alive, |
|
441e946dc1af
7121618: Change type of number of GC workers to unsigned int.
jmasa
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diff
changeset
|
5862 _collector->hash_seed(worker_id)); |
|
441e946dc1af
7121618: Change type of number of GC workers to unsigned int.
jmasa
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4128
diff
changeset
|
5863 } |
|
441e946dc1af
7121618: Change type of number of GC workers to unsigned int.
jmasa
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4128
diff
changeset
|
5864 assert(work_queue(worker_id)->size() == 0, "work_queue should be empty"); |
| 0 | 5865 assert(_collector->_overflow_list == NULL, "non-empty _overflow_list"); |
| 5866 } | |
| 5867 | |
| 5868 class CMSRefEnqueueTaskProxy: public AbstractGangTask { | |
| 5869 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; | |
| 5870 EnqueueTask& _task; | |
| 5871 | |
| 5872 public: | |
| 5873 CMSRefEnqueueTaskProxy(EnqueueTask& task) | |
| 5874 : AbstractGangTask("Enqueue reference objects in parallel"), | |
| 5875 _task(task) | |
| 5876 { } | |
| 5877 | |
|
4728
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diff
changeset
|
5878 virtual void work(uint worker_id) |
| 0 | 5879 { |
|
4728
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parents:
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diff
changeset
|
5880 _task.work(worker_id); |
| 0 | 5881 } |
| 5882 }; | |
| 5883 | |
| 5884 CMSParKeepAliveClosure::CMSParKeepAliveClosure(CMSCollector* collector, | |
|
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6964458: Reimplement class meta-data storage to use native memory
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diff
changeset
|
5885 MemRegion span, CMSBitMap* bit_map, OopTaskQueue* work_queue): |
| 0 | 5886 _span(span), |
| 5887 _bit_map(bit_map), | |
| 5888 _work_queue(work_queue), | |
|
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diff
changeset
|
5889 _mark_and_push(collector, span, bit_map, work_queue), |
| 0 | 5890 _low_water_mark(MIN2((uint)(work_queue->max_elems()/4), |
| 5891 (uint)(CMSWorkQueueDrainThreshold * ParallelGCThreads))) | |
| 5892 { } | |
| 5893 | |
| 5894 // . see if we can share work_queues with ParNew? XXX | |
| 5895 void CMSRefProcTaskProxy::do_work_steal(int i, | |
| 5896 CMSParDrainMarkingStackClosure* drain, | |
| 5897 CMSParKeepAliveClosure* keep_alive, | |
| 5898 int* seed) { | |
| 5899 OopTaskQueue* work_q = work_queue(i); | |
| 5900 NOT_PRODUCT(int num_steals = 0;) | |
| 5901 oop obj_to_scan; | |
| 5902 | |
| 5903 while (true) { | |
| 5904 // Completely finish any left over work from (an) earlier round(s) | |
| 5905 drain->trim_queue(0); | |
|
679
cea947c8a988
6819891: ParNew: Fix work queue overflow code to deal correctly with +UseCompressedOops
ysr
parents:
628
diff
changeset
|
5906 size_t num_from_overflow_list = MIN2((size_t)(work_q->max_elems() - work_q->size())/4, |
|
cea947c8a988
6819891: ParNew: Fix work queue overflow code to deal correctly with +UseCompressedOops
ysr
parents:
628
diff
changeset
|
5907 (size_t)ParGCDesiredObjsFromOverflowList); |
| 0 | 5908 // Now check if there's any work in the overflow list |
|
1833
8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
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1777
diff
changeset
|
5909 // Passing ParallelGCThreads as the third parameter, no_of_gc_threads, |
|
8b10f48633dc
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parents:
1777
diff
changeset
|
5910 // only affects the number of attempts made to get work from the |
|
8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
jmasa
parents:
1777
diff
changeset
|
5911 // overflow list and does not affect the number of workers. Just |
|
8b10f48633dc
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jmasa
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diff
changeset
|
5912 // pass ParallelGCThreads so this behavior is unchanged. |
| 0 | 5913 if (_collector->par_take_from_overflow_list(num_from_overflow_list, |
|
1833
8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
jmasa
parents:
1777
diff
changeset
|
5914 work_q, |
|
8b10f48633dc
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parents:
1777
diff
changeset
|
5915 ParallelGCThreads)) { |
| 0 | 5916 // Found something in global overflow list; |
| 5917 // not yet ready to go stealing work from others. | |
| 5918 // We'd like to assert(work_q->size() != 0, ...) | |
| 5919 // because we just took work from the overflow list, | |
| 5920 // but of course we can't, since all of that might have | |
| 5921 // been already stolen from us. | |
| 5922 continue; | |
| 5923 } | |
| 5924 // Verify that we have no work before we resort to stealing | |
| 5925 assert(work_q->size() == 0, "Have work, shouldn't steal"); | |
| 5926 // Try to steal from other queues that have work | |
| 5927 if (task_queues()->steal(i, seed, /* reference */ obj_to_scan)) { | |
| 5928 NOT_PRODUCT(num_steals++;) | |
| 5929 assert(obj_to_scan->is_oop(), "Oops, not an oop!"); | |
| 5930 assert(_mark_bit_map->isMarked((HeapWord*)obj_to_scan), "Stole an unmarked oop?"); | |
| 5931 // Do scanning work | |
| 5932 obj_to_scan->oop_iterate(keep_alive); | |
| 5933 // Loop around, finish this work, and try to steal some more | |
| 5934 } else if (terminator()->offer_termination()) { | |
| 5935 break; // nirvana from the infinite cycle | |
| 5936 } | |
| 5937 } | |
| 5938 NOT_PRODUCT( | |
| 5939 if (PrintCMSStatistics != 0) { | |
| 5940 gclog_or_tty->print("\n\t(%d: stole %d oops)", i, num_steals); | |
| 5941 } | |
| 5942 ) | |
| 5943 } | |
| 5944 | |
| 5945 void CMSRefProcTaskExecutor::execute(ProcessTask& task) | |
| 5946 { | |
| 5947 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
|
1833
8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
jmasa
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1777
diff
changeset
|
5948 FlexibleWorkGang* workers = gch->workers(); |
| 0 | 5949 assert(workers != NULL, "Need parallel worker threads."); |
| 5950 CMSRefProcTaskProxy rp_task(task, &_collector, | |
| 5951 _collector.ref_processor()->span(), | |
| 5952 _collector.markBitMap(), | |
|
1833
8b10f48633dc
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jmasa
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1777
diff
changeset
|
5953 workers, _collector.task_queues()); |
| 0 | 5954 workers->run_task(&rp_task); |
| 5955 } | |
| 5956 | |
| 5957 void CMSRefProcTaskExecutor::execute(EnqueueTask& task) | |
| 5958 { | |
| 5959 | |
| 5960 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
|
1833
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6984287: Regularize how GC parallel workers are specified.
jmasa
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1777
diff
changeset
|
5961 FlexibleWorkGang* workers = gch->workers(); |
| 0 | 5962 assert(workers != NULL, "Need parallel worker threads."); |
| 5963 CMSRefEnqueueTaskProxy enq_task(task); | |
| 5964 workers->run_task(&enq_task); | |
| 5965 } | |
| 5966 | |
| 5967 void CMSCollector::refProcessingWork(bool asynch, bool clear_all_soft_refs) { | |
| 5968 | |
| 5969 ResourceMark rm; | |
| 5970 HandleMark hm; | |
| 5971 | |
| 5972 ReferenceProcessor* rp = ref_processor(); | |
| 5973 assert(rp->span().equals(_span), "Spans should be equal"); | |
|
453
c96030fff130
6684579: SoftReference processing can be made more efficient
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452
diff
changeset
|
5974 assert(!rp->enqueuing_is_done(), "Enqueuing should not be complete"); |
|
c96030fff130
6684579: SoftReference processing can be made more efficient
ysr
parents:
452
diff
changeset
|
5975 // Process weak references. |
|
457
27a80744a83b
6778647: snap(), snap_policy() should be renamed setup(), setup_policy()
ysr
parents:
453
diff
changeset
|
5976 rp->setup_policy(clear_all_soft_refs); |
|
453
c96030fff130
6684579: SoftReference processing can be made more efficient
ysr
parents:
452
diff
changeset
|
5977 verify_work_stacks_empty(); |
|
c96030fff130
6684579: SoftReference processing can be made more efficient
ysr
parents:
452
diff
changeset
|
5978 |
| 0 | 5979 CMSKeepAliveClosure cmsKeepAliveClosure(this, _span, &_markBitMap, |
|
6725
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
5980 &_markStack, false /* !preclean */); |
| 0 | 5981 CMSDrainMarkingStackClosure cmsDrainMarkingStackClosure(this, |
| 5982 _span, &_markBitMap, &_markStack, | |
|
452
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
5983 &cmsKeepAliveClosure, false /* !preclean */); |
| 0 | 5984 { |
| 5985 TraceTime t("weak refs processing", PrintGCDetails, false, gclog_or_tty); | |
| 5986 if (rp->processing_is_mt()) { | |
|
1833
8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
jmasa
parents:
1777
diff
changeset
|
5987 // Set the degree of MT here. If the discovery is done MT, there |
|
8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
jmasa
parents:
1777
diff
changeset
|
5988 // may have been a different number of threads doing the discovery |
|
8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
jmasa
parents:
1777
diff
changeset
|
5989 // and a different number of discovered lists may have Ref objects. |
|
8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
jmasa
parents:
1777
diff
changeset
|
5990 // That is OK as long as the Reference lists are balanced (see |
|
8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
jmasa
parents:
1777
diff
changeset
|
5991 // balance_all_queues() and balance_queues()). |
|
4095
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
parents:
3979
diff
changeset
|
5992 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
parents:
3979
diff
changeset
|
5993 int active_workers = ParallelGCThreads; |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
parents:
3979
diff
changeset
|
5994 FlexibleWorkGang* workers = gch->workers(); |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
parents:
3979
diff
changeset
|
5995 if (workers != NULL) { |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
parents:
3979
diff
changeset
|
5996 active_workers = workers->active_workers(); |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
parents:
3979
diff
changeset
|
5997 // The expectation is that active_workers will have already |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
parents:
3979
diff
changeset
|
5998 // been set to a reasonable value. If it has not been set, |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
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3979
diff
changeset
|
5999 // investigate. |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
parents:
3979
diff
changeset
|
6000 assert(active_workers > 0, "Should have been set during scavenge"); |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
parents:
3979
diff
changeset
|
6001 } |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
parents:
3979
diff
changeset
|
6002 rp->set_active_mt_degree(active_workers); |
| 0 | 6003 CMSRefProcTaskExecutor task_executor(*this); |
|
453
c96030fff130
6684579: SoftReference processing can be made more efficient
ysr
parents:
452
diff
changeset
|
6004 rp->process_discovered_references(&_is_alive_closure, |
| 0 | 6005 &cmsKeepAliveClosure, |
| 6006 &cmsDrainMarkingStackClosure, | |
| 6007 &task_executor); | |
| 6008 } else { | |
|
453
c96030fff130
6684579: SoftReference processing can be made more efficient
ysr
parents:
452
diff
changeset
|
6009 rp->process_discovered_references(&_is_alive_closure, |
| 0 | 6010 &cmsKeepAliveClosure, |
| 6011 &cmsDrainMarkingStackClosure, | |
| 6012 NULL); | |
| 6013 } | |
| 6014 verify_work_stacks_empty(); | |
| 6015 } | |
| 6016 | |
|
94
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
6017 if (should_unload_classes()) { |
| 0 | 6018 { |
| 6019 TraceTime t("class unloading", PrintGCDetails, false, gclog_or_tty); | |
| 6020 | |
| 6021 // Follow SystemDictionary roots and unload classes | |
| 6022 bool purged_class = SystemDictionary::do_unloading(&_is_alive_closure); | |
| 6023 | |
| 6024 // Follow CodeCache roots and unload any methods marked for unloading | |
|
6787
8966c2d65d96
7200470: KeepAliveClosure not needed in CodeCache::do_unloading
brutisso
parents:
6755
diff
changeset
|
6025 CodeCache::do_unloading(&_is_alive_closure, purged_class); |
| 0 | 6026 |
| 6027 cmsDrainMarkingStackClosure.do_void(); | |
| 6028 verify_work_stacks_empty(); | |
| 6029 | |
| 6030 // Update subklass/sibling/implementor links in KlassKlass descendants | |
|
6725
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
6031 Klass::clean_weak_klass_links(&_is_alive_closure); |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
6032 // Nothing should have been pushed onto the working stacks. |
| 0 | 6033 verify_work_stacks_empty(); |
| 6034 } | |
| 6035 | |
| 6036 { | |
|
2379
b099aaf51bf8
6962931: move interned strings out of the perm gen
jcoomes
parents:
2369
diff
changeset
|
6037 TraceTime t("scrub symbol table", PrintGCDetails, false, gclog_or_tty); |
|
2177
3582bf76420e
6990754: Use native memory and reference counting to implement SymbolTable
coleenp
parents:
2147
diff
changeset
|
6038 // Clean up unreferenced symbols in symbol table. |
|
3582bf76420e
6990754: Use native memory and reference counting to implement SymbolTable
coleenp
parents:
2147
diff
changeset
|
6039 SymbolTable::unlink(); |
| 0 | 6040 } |
| 6041 } | |
| 6042 | |
|
6725
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
6043 // CMS doesn't use the StringTable as hard roots when class unloading is turned off. |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
6044 // Need to check if we really scanned the StringTable. |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
6045 if ((roots_scanning_options() & SharedHeap::SO_Strings) == 0) { |
|
2379
b099aaf51bf8
6962931: move interned strings out of the perm gen
jcoomes
parents:
2369
diff
changeset
|
6046 TraceTime t("scrub string table", PrintGCDetails, false, gclog_or_tty); |
|
b099aaf51bf8
6962931: move interned strings out of the perm gen
jcoomes
parents:
2369
diff
changeset
|
6047 // Now clean up stale oops in StringTable |
|
b099aaf51bf8
6962931: move interned strings out of the perm gen
jcoomes
parents:
2369
diff
changeset
|
6048 StringTable::unlink(&_is_alive_closure); |
|
b099aaf51bf8
6962931: move interned strings out of the perm gen
jcoomes
parents:
2369
diff
changeset
|
6049 } |
|
b099aaf51bf8
6962931: move interned strings out of the perm gen
jcoomes
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2369
diff
changeset
|
6050 |
| 0 | 6051 verify_work_stacks_empty(); |
| 6052 // Restore any preserved marks as a result of mark stack or | |
| 6053 // work queue overflow | |
| 6054 restore_preserved_marks_if_any(); // done single-threaded for now | |
| 6055 | |
| 6056 rp->set_enqueuing_is_done(true); | |
| 6057 if (rp->processing_is_mt()) { | |
|
1833
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6984287: Regularize how GC parallel workers are specified.
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1777
diff
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|
6058 rp->balance_all_queues(); |
| 0 | 6059 CMSRefProcTaskExecutor task_executor(*this); |
| 6060 rp->enqueue_discovered_references(&task_executor); | |
| 6061 } else { | |
| 6062 rp->enqueue_discovered_references(NULL); | |
| 6063 } | |
| 6064 rp->verify_no_references_recorded(); | |
| 6065 assert(!rp->discovery_enabled(), "should have been disabled"); | |
| 6066 } | |
| 6067 | |
| 6068 #ifndef PRODUCT | |
| 6069 void CMSCollector::check_correct_thread_executing() { | |
| 6070 Thread* t = Thread::current(); | |
| 6071 // Only the VM thread or the CMS thread should be here. | |
| 6072 assert(t->is_ConcurrentGC_thread() || t->is_VM_thread(), | |
| 6073 "Unexpected thread type"); | |
| 6074 // If this is the vm thread, the foreground process | |
| 6075 // should not be waiting. Note that _foregroundGCIsActive is | |
| 6076 // true while the foreground collector is waiting. | |
| 6077 if (_foregroundGCShouldWait) { | |
| 6078 // We cannot be the VM thread | |
| 6079 assert(t->is_ConcurrentGC_thread(), | |
| 6080 "Should be CMS thread"); | |
| 6081 } else { | |
| 6082 // We can be the CMS thread only if we are in a stop-world | |
| 6083 // phase of CMS collection. | |
| 6084 if (t->is_ConcurrentGC_thread()) { | |
| 6085 assert(_collectorState == InitialMarking || | |
| 6086 _collectorState == FinalMarking, | |
| 6087 "Should be a stop-world phase"); | |
| 6088 // The CMS thread should be holding the CMS_token. | |
| 6089 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 6090 "Potential interference with concurrently " | |
| 6091 "executing VM thread"); | |
| 6092 } | |
| 6093 } | |
| 6094 } | |
| 6095 #endif | |
| 6096 | |
| 6097 void CMSCollector::sweep(bool asynch) { | |
| 6098 assert(_collectorState == Sweeping, "just checking"); | |
| 6099 check_correct_thread_executing(); | |
| 6100 verify_work_stacks_empty(); | |
| 6101 verify_overflow_empty(); | |
|
1145
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
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1085
diff
changeset
|
6102 increment_sweep_count(); |
|
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
parents:
3293
diff
changeset
|
6103 TraceCMSMemoryManagerStats tms(_collectorState,GenCollectedHeap::heap()->gc_cause()); |
|
1703
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
6104 |
|
1145
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
6105 _inter_sweep_timer.stop(); |
|
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
6106 _inter_sweep_estimate.sample(_inter_sweep_timer.seconds()); |
| 0 | 6107 size_policy()->avg_cms_free_at_sweep()->sample(_cmsGen->free()); |
| 6108 | |
|
1145
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
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1085
diff
changeset
|
6109 assert(!_intra_sweep_timer.is_active(), "Should not be active"); |
|
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6110 _intra_sweep_timer.reset(); |
|
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6111 _intra_sweep_timer.start(); |
| 0 | 6112 if (asynch) { |
| 6113 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
| 6114 CMSPhaseAccounting pa(this, "sweep", !PrintGCDetails); | |
|
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|
6115 // First sweep the old gen |
| 0 | 6116 { |
| 6117 CMSTokenSyncWithLocks ts(true, _cmsGen->freelistLock(), | |
| 6118 bitMapLock()); | |
| 6119 sweepWork(_cmsGen, asynch); | |
| 6120 } | |
| 6121 | |
| 6122 // Update Universe::_heap_*_at_gc figures. | |
| 6123 // We need all the free list locks to make the abstract state | |
| 6124 // transition from Sweeping to Resetting. See detailed note | |
| 6125 // further below. | |
| 6126 { | |
|
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|
6127 CMSTokenSyncWithLocks ts(true, _cmsGen->freelistLock()); |
| 0 | 6128 // Update heap occupancy information which is used as |
| 6129 // input to soft ref clearing policy at the next gc. | |
| 6130 Universe::update_heap_info_at_gc(); | |
| 6131 _collectorState = Resizing; | |
| 6132 } | |
| 6133 } else { | |
| 6134 // already have needed locks | |
| 6135 sweepWork(_cmsGen, asynch); | |
| 6136 // Update heap occupancy information which is used as | |
| 6137 // input to soft ref clearing policy at the next gc. | |
| 6138 Universe::update_heap_info_at_gc(); | |
| 6139 _collectorState = Resizing; | |
| 6140 } | |
| 6141 verify_work_stacks_empty(); | |
| 6142 verify_overflow_empty(); | |
| 6143 | |
|
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|
6144 if (should_unload_classes()) { |
|
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|
6145 ClassLoaderDataGraph::purge(); |
|
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|
6146 } |
|
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|
6147 |
|
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6148 _intra_sweep_timer.stop(); |
|
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|
6149 _intra_sweep_estimate.sample(_intra_sweep_timer.seconds()); |
|
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|
6150 |
|
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|
6151 _inter_sweep_timer.reset(); |
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|
6152 _inter_sweep_timer.start(); |
| 0 | 6153 |
| 4911 | 6154 // We need to use a monotonically non-deccreasing time in ms |
| 6155 // or we will see time-warp warnings and os::javaTimeMillis() | |
| 6156 // does not guarantee monotonicity. | |
| 6157 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; | |
| 6158 update_time_of_last_gc(now); | |
| 0 | 6159 |
| 6160 // NOTE on abstract state transitions: | |
| 6161 // Mutators allocate-live and/or mark the mod-union table dirty | |
| 6162 // based on the state of the collection. The former is done in | |
| 6163 // the interval [Marking, Sweeping] and the latter in the interval | |
| 6164 // [Marking, Sweeping). Thus the transitions into the Marking state | |
| 6165 // and out of the Sweeping state must be synchronously visible | |
| 6166 // globally to the mutators. | |
| 6167 // The transition into the Marking state happens with the world | |
| 6168 // stopped so the mutators will globally see it. Sweeping is | |
| 6169 // done asynchronously by the background collector so the transition | |
| 6170 // from the Sweeping state to the Resizing state must be done | |
| 6171 // under the freelistLock (as is the check for whether to | |
| 6172 // allocate-live and whether to dirty the mod-union table). | |
| 6173 assert(_collectorState == Resizing, "Change of collector state to" | |
| 6174 " Resizing must be done under the freelistLocks (plural)"); | |
| 6175 | |
|
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6176 // Now that sweeping has been completed, we clear |
|
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|
6177 // the incremental_collection_failed flag, |
| 0 | 6178 // thus inviting a younger gen collection to promote into |
| 6179 // this generation. If such a promotion may still fail, | |
| 6180 // the flag will be set again when a young collection is | |
| 6181 // attempted. | |
| 6182 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
|
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|
6183 gch->clear_incremental_collection_failed(); // Worth retrying as fresh space may have been freed up |
| 0 | 6184 gch->update_full_collections_completed(_collection_count_start); |
| 6185 } | |
| 6186 | |
| 6187 // FIX ME!!! Looks like this belongs in CFLSpace, with | |
| 6188 // CMSGen merely delegating to it. | |
| 6189 void ConcurrentMarkSweepGeneration::setNearLargestChunk() { | |
|
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|
6190 double nearLargestPercent = FLSLargestBlockCoalesceProximity; |
| 0 | 6191 HeapWord* minAddr = _cmsSpace->bottom(); |
| 6192 HeapWord* largestAddr = | |
|
6028
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|
6193 (HeapWord*) _cmsSpace->dictionary()->find_largest_dict(); |
|
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|
6194 if (largestAddr == NULL) { |
| 0 | 6195 // The dictionary appears to be empty. In this case |
| 6196 // try to coalesce at the end of the heap. | |
| 6197 largestAddr = _cmsSpace->end(); | |
| 6198 } | |
| 6199 size_t largestOffset = pointer_delta(largestAddr, minAddr); | |
| 6200 size_t nearLargestOffset = | |
| 6201 (size_t)((double)largestOffset * nearLargestPercent) - MinChunkSize; | |
|
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|
6202 if (PrintFLSStatistics != 0) { |
|
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|
6203 gclog_or_tty->print_cr( |
|
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|
6204 "CMS: Large Block: " PTR_FORMAT ";" |
|
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|
6205 " Proximity: " PTR_FORMAT " -> " PTR_FORMAT, |
|
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|
6206 largestAddr, |
|
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|
6207 _cmsSpace->nearLargestChunk(), minAddr + nearLargestOffset); |
|
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|
6208 } |
| 0 | 6209 _cmsSpace->set_nearLargestChunk(minAddr + nearLargestOffset); |
| 6210 } | |
| 6211 | |
| 6212 bool ConcurrentMarkSweepGeneration::isNearLargestChunk(HeapWord* addr) { | |
| 6213 return addr >= _cmsSpace->nearLargestChunk(); | |
| 6214 } | |
| 6215 | |
| 6216 FreeChunk* ConcurrentMarkSweepGeneration::find_chunk_at_end() { | |
| 6217 return _cmsSpace->find_chunk_at_end(); | |
| 6218 } | |
| 6219 | |
| 6220 void ConcurrentMarkSweepGeneration::update_gc_stats(int current_level, | |
| 6221 bool full) { | |
| 6222 // The next lower level has been collected. Gather any statistics | |
| 6223 // that are of interest at this point. | |
| 6224 if (!full && (current_level + 1) == level()) { | |
| 6225 // Gather statistics on the young generation collection. | |
| 6226 collector()->stats().record_gc0_end(used()); | |
| 6227 } | |
| 6228 } | |
| 6229 | |
| 6230 CMSAdaptiveSizePolicy* ConcurrentMarkSweepGeneration::size_policy() { | |
| 6231 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 6232 assert(gch->kind() == CollectedHeap::GenCollectedHeap, | |
| 6233 "Wrong type of heap"); | |
| 6234 CMSAdaptiveSizePolicy* sp = (CMSAdaptiveSizePolicy*) | |
| 6235 gch->gen_policy()->size_policy(); | |
| 6236 assert(sp->is_gc_cms_adaptive_size_policy(), | |
| 6237 "Wrong type of size policy"); | |
| 6238 return sp; | |
| 6239 } | |
| 6240 | |
| 6241 void ConcurrentMarkSweepGeneration::rotate_debug_collection_type() { | |
| 6242 if (PrintGCDetails && Verbose) { | |
| 6243 gclog_or_tty->print("Rotate from %d ", _debug_collection_type); | |
| 6244 } | |
| 6245 _debug_collection_type = (CollectionTypes) (_debug_collection_type + 1); | |
| 6246 _debug_collection_type = | |
| 6247 (CollectionTypes) (_debug_collection_type % Unknown_collection_type); | |
| 6248 if (PrintGCDetails && Verbose) { | |
| 6249 gclog_or_tty->print_cr("to %d ", _debug_collection_type); | |
| 6250 } | |
| 6251 } | |
| 6252 | |
| 6253 void CMSCollector::sweepWork(ConcurrentMarkSweepGeneration* gen, | |
| 6254 bool asynch) { | |
| 6255 // We iterate over the space(s) underlying this generation, | |
| 6256 // checking the mark bit map to see if the bits corresponding | |
| 6257 // to specific blocks are marked or not. Blocks that are | |
| 6258 // marked are live and are not swept up. All remaining blocks | |
| 6259 // are swept up, with coalescing on-the-fly as we sweep up | |
| 6260 // contiguous free and/or garbage blocks: | |
| 6261 // We need to ensure that the sweeper synchronizes with allocators | |
| 6262 // and stop-the-world collectors. In particular, the following | |
| 6263 // locks are used: | |
| 6264 // . CMS token: if this is held, a stop the world collection cannot occur | |
| 6265 // . freelistLock: if this is held no allocation can occur from this | |
| 6266 // generation by another thread | |
| 6267 // . bitMapLock: if this is held, no other thread can access or update | |
| 6268 // | |
| 6269 | |
| 6270 // Note that we need to hold the freelistLock if we use | |
| 6271 // block iterate below; else the iterator might go awry if | |
| 6272 // a mutator (or promotion) causes block contents to change | |
| 6273 // (for instance if the allocator divvies up a block). | |
| 6274 // If we hold the free list lock, for all practical purposes | |
| 6275 // young generation GC's can't occur (they'll usually need to | |
| 6276 // promote), so we might as well prevent all young generation | |
| 6277 // GC's while we do a sweeping step. For the same reason, we might | |
| 6278 // as well take the bit map lock for the entire duration | |
| 6279 | |
| 6280 // check that we hold the requisite locks | |
| 6281 assert(have_cms_token(), "Should hold cms token"); | |
| 6282 assert( (asynch && ConcurrentMarkSweepThread::cms_thread_has_cms_token()) | |
| 6283 || (!asynch && ConcurrentMarkSweepThread::vm_thread_has_cms_token()), | |
| 6284 "Should possess CMS token to sweep"); | |
| 6285 assert_lock_strong(gen->freelistLock()); | |
| 6286 assert_lock_strong(bitMapLock()); | |
| 6287 | |
|
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|
6288 assert(!_inter_sweep_timer.is_active(), "Was switched off in an outer context"); |
|
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|
6289 assert(_intra_sweep_timer.is_active(), "Was switched on in an outer context"); |
|
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6631166: CMS: better heuristics when combatting fragmentation
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|
6290 gen->cmsSpace()->beginSweepFLCensus((float)(_inter_sweep_timer.seconds()), |
|
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|
6291 _inter_sweep_estimate.padded_average(), |
|
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|
6292 _intra_sweep_estimate.padded_average()); |
| 0 | 6293 gen->setNearLargestChunk(); |
| 6294 | |
| 6295 { | |
| 6296 SweepClosure sweepClosure(this, gen, &_markBitMap, | |
| 6297 CMSYield && asynch); | |
| 6298 gen->cmsSpace()->blk_iterate_careful(&sweepClosure); | |
| 6299 // We need to free-up/coalesce garbage/blocks from a | |
| 6300 // co-terminal free run. This is done in the SweepClosure | |
| 6301 // destructor; so, do not remove this scope, else the | |
| 6302 // end-of-sweep-census below will be off by a little bit. | |
| 6303 } | |
| 6304 gen->cmsSpace()->sweep_completed(); | |
|
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|
6305 gen->cmsSpace()->endSweepFLCensus(sweep_count()); |
|
94
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6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
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9
diff
changeset
|
6306 if (should_unload_classes()) { // unloaded classes this cycle, |
|
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
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diff
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|
6307 _concurrent_cycles_since_last_unload = 0; // ... reset count |
|
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
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diff
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|
6308 } else { // did not unload classes, |
|
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
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diff
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|
6309 _concurrent_cycles_since_last_unload++; // ... increment count |
|
0834225a7916
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|
6310 } |
| 0 | 6311 } |
| 6312 | |
| 6313 // Reset CMS data structures (for now just the marking bit map) | |
| 6314 // preparatory for the next cycle. | |
| 6315 void CMSCollector::reset(bool asynch) { | |
| 6316 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 6317 CMSAdaptiveSizePolicy* sp = size_policy(); | |
| 6318 AdaptiveSizePolicyOutput(sp, gch->total_collections()); | |
| 6319 if (asynch) { | |
| 6320 CMSTokenSyncWithLocks ts(true, bitMapLock()); | |
| 6321 | |
| 6322 // If the state is not "Resetting", the foreground thread | |
| 6323 // has done a collection and the resetting. | |
| 6324 if (_collectorState != Resetting) { | |
| 6325 assert(_collectorState == Idling, "The state should only change" | |
| 6326 " because the foreground collector has finished the collection"); | |
| 6327 return; | |
| 6328 } | |
| 6329 | |
| 6330 // Clear the mark bitmap (no grey objects to start with) | |
| 6331 // for the next cycle. | |
| 6332 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
| 6333 CMSPhaseAccounting cmspa(this, "reset", !PrintGCDetails); | |
| 6334 | |
| 6335 HeapWord* curAddr = _markBitMap.startWord(); | |
| 6336 while (curAddr < _markBitMap.endWord()) { | |
| 6337 size_t remaining = pointer_delta(_markBitMap.endWord(), curAddr); | |
| 6338 MemRegion chunk(curAddr, MIN2(CMSBitMapYieldQuantum, remaining)); | |
| 6339 _markBitMap.clear_large_range(chunk); | |
| 6340 if (ConcurrentMarkSweepThread::should_yield() && | |
| 6341 !foregroundGCIsActive() && | |
| 6342 CMSYield) { | |
| 6343 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 6344 "CMS thread should hold CMS token"); | |
| 6345 assert_lock_strong(bitMapLock()); | |
| 6346 bitMapLock()->unlock(); | |
| 6347 ConcurrentMarkSweepThread::desynchronize(true); | |
| 6348 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 6349 stopTimer(); | |
| 6350 if (PrintCMSStatistics != 0) { | |
| 6351 incrementYields(); | |
| 6352 } | |
| 6353 icms_wait(); | |
| 6354 | |
| 6355 // See the comment in coordinator_yield() | |
| 6356 for (unsigned i = 0; i < CMSYieldSleepCount && | |
|
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|
6357 ConcurrentMarkSweepThread::should_yield() && |
|
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|
6358 !CMSCollector::foregroundGCIsActive(); ++i) { |
| 0 | 6359 os::sleep(Thread::current(), 1, false); |
| 6360 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 6361 } | |
| 6362 | |
| 6363 ConcurrentMarkSweepThread::synchronize(true); | |
| 6364 bitMapLock()->lock_without_safepoint_check(); | |
| 6365 startTimer(); | |
| 6366 } | |
| 6367 curAddr = chunk.end(); | |
| 6368 } | |
|
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|
6369 // A successful mostly concurrent collection has been done. |
|
0bfd3fb24150
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diff
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|
6370 // Because only the full (i.e., concurrent mode failure) collections |
|
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|
6371 // are being measured for gc overhead limits, clean the "near" flag |
|
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|
6372 // and count. |
|
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|
6373 sp->reset_gc_overhead_limit_count(); |
| 0 | 6374 _collectorState = Idling; |
| 6375 } else { | |
| 6376 // already have the lock | |
| 6377 assert(_collectorState == Resetting, "just checking"); | |
| 6378 assert_lock_strong(bitMapLock()); | |
| 6379 _markBitMap.clear_all(); | |
| 6380 _collectorState = Idling; | |
| 6381 } | |
| 6382 | |
| 6383 // Stop incremental mode after a cycle completes, so that any future cycles | |
| 6384 // are triggered by allocation. | |
| 6385 stop_icms(); | |
| 6386 | |
| 6387 NOT_PRODUCT( | |
| 6388 if (RotateCMSCollectionTypes) { | |
| 6389 _cmsGen->rotate_debug_collection_type(); | |
| 6390 } | |
| 6391 ) | |
| 6392 } | |
| 6393 | |
|
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|
6394 void CMSCollector::do_CMS_operation(CMS_op_type op, GCCause::Cause gc_cause) { |
| 0 | 6395 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps); |
| 6396 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
|
6064
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brutisso
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|
6397 TraceTime t(GCCauseString("GC", gc_cause), PrintGC, !PrintGCDetails, gclog_or_tty); |
| 0 | 6398 TraceCollectorStats tcs(counters()); |
| 6399 | |
| 6400 switch (op) { | |
| 6401 case CMS_op_checkpointRootsInitial: { | |
|
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kamg
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1994
diff
changeset
|
6402 SvcGCMarker sgcm(SvcGCMarker::OTHER); |
| 0 | 6403 checkpointRootsInitial(true); // asynch |
| 6404 if (PrintGC) { | |
| 6405 _cmsGen->printOccupancy("initial-mark"); | |
| 6406 } | |
| 6407 break; | |
| 6408 } | |
| 6409 case CMS_op_checkpointRootsFinal: { | |
|
2125
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6458402: 3 jvmti tests fail with CMS and +ExplicitGCInvokesConcurrent
kamg
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1994
diff
changeset
|
6410 SvcGCMarker sgcm(SvcGCMarker::OTHER); |
| 0 | 6411 checkpointRootsFinal(true, // asynch |
| 6412 false, // !clear_all_soft_refs | |
| 6413 false); // !init_mark_was_synchronous | |
| 6414 if (PrintGC) { | |
| 6415 _cmsGen->printOccupancy("remark"); | |
| 6416 } | |
| 6417 break; | |
| 6418 } | |
| 6419 default: | |
| 6420 fatal("No such CMS_op"); | |
| 6421 } | |
| 6422 } | |
| 6423 | |
| 6424 #ifndef PRODUCT | |
| 6425 size_t const CMSCollector::skip_header_HeapWords() { | |
| 6426 return FreeChunk::header_size(); | |
| 6427 } | |
| 6428 | |
| 6429 // Try and collect here conditions that should hold when | |
| 6430 // CMS thread is exiting. The idea is that the foreground GC | |
| 6431 // thread should not be blocked if it wants to terminate | |
| 6432 // the CMS thread and yet continue to run the VM for a while | |
| 6433 // after that. | |
| 6434 void CMSCollector::verify_ok_to_terminate() const { | |
| 6435 assert(Thread::current()->is_ConcurrentGC_thread(), | |
| 6436 "should be called by CMS thread"); | |
| 6437 assert(!_foregroundGCShouldWait, "should be false"); | |
| 6438 // We could check here that all the various low-level locks | |
| 6439 // are not held by the CMS thread, but that is overkill; see | |
| 6440 // also CMSThread::verify_ok_to_terminate() where the CGC_lock | |
| 6441 // is checked. | |
| 6442 } | |
| 6443 #endif | |
| 6444 | |
| 6445 size_t CMSCollector::block_size_using_printezis_bits(HeapWord* addr) const { | |
|
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6446 assert(_markBitMap.isMarked(addr) && _markBitMap.isMarked(addr + 1), |
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6447 "missing Printezis mark?"); |
| 0 | 6448 HeapWord* nextOneAddr = _markBitMap.getNextMarkedWordAddress(addr + 2); |
| 6449 size_t size = pointer_delta(nextOneAddr + 1, addr); | |
| 6450 assert(size == CompactibleFreeListSpace::adjustObjectSize(size), | |
| 6451 "alignment problem"); | |
| 6452 assert(size >= 3, "Necessary for Printezis marks to work"); | |
| 6453 return size; | |
| 6454 } | |
| 6455 | |
| 6456 // A variant of the above (block_size_using_printezis_bits()) except | |
| 6457 // that we return 0 if the P-bits are not yet set. | |
| 6458 size_t CMSCollector::block_size_if_printezis_bits(HeapWord* addr) const { | |
|
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6459 if (_markBitMap.isMarked(addr + 1)) { |
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6460 assert(_markBitMap.isMarked(addr), "P-bit can be set only for marked objects"); |
| 0 | 6461 HeapWord* nextOneAddr = _markBitMap.getNextMarkedWordAddress(addr + 2); |
| 6462 size_t size = pointer_delta(nextOneAddr + 1, addr); | |
| 6463 assert(size == CompactibleFreeListSpace::adjustObjectSize(size), | |
| 6464 "alignment problem"); | |
| 6465 assert(size >= 3, "Necessary for Printezis marks to work"); | |
| 6466 return size; | |
|
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6467 } |
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6468 return 0; |
| 0 | 6469 } |
| 6470 | |
| 6471 HeapWord* CMSCollector::next_card_start_after_block(HeapWord* addr) const { | |
| 6472 size_t sz = 0; | |
| 6473 oop p = (oop)addr; | |
|
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6474 if (p->klass_or_null() != NULL) { |
| 0 | 6475 sz = CompactibleFreeListSpace::adjustObjectSize(p->size()); |
| 6476 } else { | |
| 6477 sz = block_size_using_printezis_bits(addr); | |
| 6478 } | |
| 6479 assert(sz > 0, "size must be nonzero"); | |
| 6480 HeapWord* next_block = addr + sz; | |
| 6481 HeapWord* next_card = (HeapWord*)round_to((uintptr_t)next_block, | |
| 6482 CardTableModRefBS::card_size); | |
| 6483 assert(round_down((uintptr_t)addr, CardTableModRefBS::card_size) < | |
| 6484 round_down((uintptr_t)next_card, CardTableModRefBS::card_size), | |
| 6485 "must be different cards"); | |
| 6486 return next_card; | |
| 6487 } | |
| 6488 | |
| 6489 | |
| 6490 // CMS Bit Map Wrapper ///////////////////////////////////////// | |
| 6491 | |
| 6492 // Construct a CMS bit map infrastructure, but don't create the | |
| 6493 // bit vector itself. That is done by a separate call CMSBitMap::allocate() | |
| 6494 // further below. | |
| 6495 CMSBitMap::CMSBitMap(int shifter, int mutex_rank, const char* mutex_name): | |
|
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6496 _bm(), |
| 0 | 6497 _shifter(shifter), |
| 6498 _lock(mutex_rank >= 0 ? new Mutex(mutex_rank, mutex_name, true) : NULL) | |
| 6499 { | |
| 6500 _bmStartWord = 0; | |
| 6501 _bmWordSize = 0; | |
| 6502 } | |
| 6503 | |
| 6504 bool CMSBitMap::allocate(MemRegion mr) { | |
| 6505 _bmStartWord = mr.start(); | |
| 6506 _bmWordSize = mr.word_size(); | |
| 6507 ReservedSpace brs(ReservedSpace::allocation_align_size_up( | |
| 6508 (_bmWordSize >> (_shifter + LogBitsPerByte)) + 1)); | |
| 6509 if (!brs.is_reserved()) { | |
| 6510 warning("CMS bit map allocation failure"); | |
| 6511 return false; | |
| 6512 } | |
| 6513 // For now we'll just commit all of the bit map up fromt. | |
| 6514 // Later on we'll try to be more parsimonious with swap. | |
| 6515 if (!_virtual_space.initialize(brs, brs.size())) { | |
| 6516 warning("CMS bit map backing store failure"); | |
| 6517 return false; | |
| 6518 } | |
| 6519 assert(_virtual_space.committed_size() == brs.size(), | |
| 6520 "didn't reserve backing store for all of CMS bit map?"); | |
|
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6521 _bm.set_map((BitMap::bm_word_t*)_virtual_space.low()); |
| 0 | 6522 assert(_virtual_space.committed_size() << (_shifter + LogBitsPerByte) >= |
| 6523 _bmWordSize, "inconsistency in bit map sizing"); | |
| 6524 _bm.set_size(_bmWordSize >> _shifter); | |
| 6525 | |
| 6526 // bm.clear(); // can we rely on getting zero'd memory? verify below | |
| 6527 assert(isAllClear(), | |
| 6528 "Expected zero'd memory from ReservedSpace constructor"); | |
| 6529 assert(_bm.size() == heapWordDiffToOffsetDiff(sizeInWords()), | |
| 6530 "consistency check"); | |
| 6531 return true; | |
| 6532 } | |
| 6533 | |
| 6534 void CMSBitMap::dirty_range_iterate_clear(MemRegion mr, MemRegionClosure* cl) { | |
| 6535 HeapWord *next_addr, *end_addr, *last_addr; | |
| 6536 assert_locked(); | |
| 6537 assert(covers(mr), "out-of-range error"); | |
| 6538 // XXX assert that start and end are appropriately aligned | |
| 6539 for (next_addr = mr.start(), end_addr = mr.end(); | |
| 6540 next_addr < end_addr; next_addr = last_addr) { | |
| 6541 MemRegion dirty_region = getAndClearMarkedRegion(next_addr, end_addr); | |
| 6542 last_addr = dirty_region.end(); | |
| 6543 if (!dirty_region.is_empty()) { | |
| 6544 cl->do_MemRegion(dirty_region); | |
| 6545 } else { | |
| 6546 assert(last_addr == end_addr, "program logic"); | |
| 6547 return; | |
| 6548 } | |
| 6549 } | |
| 6550 } | |
| 6551 | |
|
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6552 void CMSBitMap::print_on_error(outputStream* st, const char* prefix) const { |
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6553 _bm.print_on_error(st, prefix); |
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6554 } |
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6555 |
| 0 | 6556 #ifndef PRODUCT |
| 6557 void CMSBitMap::assert_locked() const { | |
| 6558 CMSLockVerifier::assert_locked(lock()); | |
| 6559 } | |
| 6560 | |
| 6561 bool CMSBitMap::covers(MemRegion mr) const { | |
| 6562 // assert(_bm.map() == _virtual_space.low(), "map inconsistency"); | |
| 6563 assert((size_t)_bm.size() == (_bmWordSize >> _shifter), | |
| 6564 "size inconsistency"); | |
| 6565 return (mr.start() >= _bmStartWord) && | |
| 6566 (mr.end() <= endWord()); | |
| 6567 } | |
| 6568 | |
| 6569 bool CMSBitMap::covers(HeapWord* start, size_t size) const { | |
| 6570 return (start >= _bmStartWord && (start + size) <= endWord()); | |
| 6571 } | |
| 6572 | |
| 6573 void CMSBitMap::verifyNoOneBitsInRange(HeapWord* left, HeapWord* right) { | |
| 6574 // verify that there are no 1 bits in the interval [left, right) | |
| 6575 FalseBitMapClosure falseBitMapClosure; | |
| 6576 iterate(&falseBitMapClosure, left, right); | |
| 6577 } | |
| 6578 | |
| 6579 void CMSBitMap::region_invariant(MemRegion mr) | |
| 6580 { | |
| 6581 assert_locked(); | |
| 6582 // mr = mr.intersection(MemRegion(_bmStartWord, _bmWordSize)); | |
| 6583 assert(!mr.is_empty(), "unexpected empty region"); | |
| 6584 assert(covers(mr), "mr should be covered by bit map"); | |
| 6585 // convert address range into offset range | |
| 6586 size_t start_ofs = heapWordToOffset(mr.start()); | |
| 6587 // Make sure that end() is appropriately aligned | |
| 6588 assert(mr.end() == (HeapWord*)round_to((intptr_t)mr.end(), | |
| 6589 (1 << (_shifter+LogHeapWordSize))), | |
| 6590 "Misaligned mr.end()"); | |
| 6591 size_t end_ofs = heapWordToOffset(mr.end()); | |
| 6592 assert(end_ofs > start_ofs, "Should mark at least one bit"); | |
| 6593 } | |
| 6594 | |
| 6595 #endif | |
| 6596 | |
| 6597 bool CMSMarkStack::allocate(size_t size) { | |
| 6598 // allocate a stack of the requisite depth | |
| 6599 ReservedSpace rs(ReservedSpace::allocation_align_size_up( | |
| 6600 size * sizeof(oop))); | |
| 6601 if (!rs.is_reserved()) { | |
| 6602 warning("CMSMarkStack allocation failure"); | |
| 6603 return false; | |
| 6604 } | |
| 6605 if (!_virtual_space.initialize(rs, rs.size())) { | |
| 6606 warning("CMSMarkStack backing store failure"); | |
| 6607 return false; | |
| 6608 } | |
| 6609 assert(_virtual_space.committed_size() == rs.size(), | |
| 6610 "didn't reserve backing store for all of CMS stack?"); | |
| 6611 _base = (oop*)(_virtual_space.low()); | |
| 6612 _index = 0; | |
| 6613 _capacity = size; | |
| 6614 NOT_PRODUCT(_max_depth = 0); | |
| 6615 return true; | |
| 6616 } | |
| 6617 | |
| 6618 // XXX FIX ME !!! In the MT case we come in here holding a | |
| 6619 // leaf lock. For printing we need to take a further lock | |
| 6620 // which has lower rank. We need to recallibrate the two | |
| 6621 // lock-ranks involved in order to be able to rpint the | |
| 6622 // messages below. (Or defer the printing to the caller. | |
| 6623 // For now we take the expedient path of just disabling the | |
| 6624 // messages for the problematic case.) | |
| 6625 void CMSMarkStack::expand() { | |
| 1284 | 6626 assert(_capacity <= MarkStackSizeMax, "stack bigger than permitted"); |
| 6627 if (_capacity == MarkStackSizeMax) { | |
| 0 | 6628 if (_hit_limit++ == 0 && !CMSConcurrentMTEnabled && PrintGCDetails) { |
| 6629 // We print a warning message only once per CMS cycle. | |
| 6630 gclog_or_tty->print_cr(" (benign) Hit CMSMarkStack max size limit"); | |
| 6631 } | |
| 6632 return; | |
| 6633 } | |
| 6634 // Double capacity if possible | |
| 1284 | 6635 size_t new_capacity = MIN2(_capacity*2, MarkStackSizeMax); |
| 0 | 6636 // Do not give up existing stack until we have managed to |
| 6637 // get the double capacity that we desired. | |
| 6638 ReservedSpace rs(ReservedSpace::allocation_align_size_up( | |
| 6639 new_capacity * sizeof(oop))); | |
| 6640 if (rs.is_reserved()) { | |
| 6641 // Release the backing store associated with old stack | |
| 6642 _virtual_space.release(); | |
| 6643 // Reinitialize virtual space for new stack | |
| 6644 if (!_virtual_space.initialize(rs, rs.size())) { | |
| 6645 fatal("Not enough swap for expanded marking stack"); | |
| 6646 } | |
| 6647 _base = (oop*)(_virtual_space.low()); | |
| 6648 _index = 0; | |
| 6649 _capacity = new_capacity; | |
| 6650 } else if (_failed_double++ == 0 && !CMSConcurrentMTEnabled && PrintGCDetails) { | |
| 6651 // Failed to double capacity, continue; | |
| 6652 // we print a detail message only once per CMS cycle. | |
| 6653 gclog_or_tty->print(" (benign) Failed to expand marking stack from "SIZE_FORMAT"K to " | |
| 6654 SIZE_FORMAT"K", | |
| 6655 _capacity / K, new_capacity / K); | |
| 6656 } | |
| 6657 } | |
| 6658 | |
| 6659 | |
| 6660 // Closures | |
| 6661 // XXX: there seems to be a lot of code duplication here; | |
| 6662 // should refactor and consolidate common code. | |
| 6663 | |
| 6664 // This closure is used to mark refs into the CMS generation in | |
| 6665 // the CMS bit map. Called at the first checkpoint. This closure | |
| 6666 // assumes that we do not need to re-mark dirty cards; if the CMS | |
|
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6667 // generation on which this is used is not an oldest |
| 0 | 6668 // generation then this will lose younger_gen cards! |
| 6669 | |
| 6670 MarkRefsIntoClosure::MarkRefsIntoClosure( | |
|
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6671 MemRegion span, CMSBitMap* bitMap): |
| 0 | 6672 _span(span), |
|
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|
6673 _bitMap(bitMap) |
| 0 | 6674 { |
| 6675 assert(_ref_processor == NULL, "deliberately left NULL"); | |
| 6676 assert(_bitMap->covers(_span), "_bitMap/_span mismatch"); | |
| 6677 } | |
| 6678 | |
|
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6679 void MarkRefsIntoClosure::do_oop(oop obj) { |
| 0 | 6680 // if p points into _span, then mark corresponding bit in _markBitMap |
|
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6681 assert(obj->is_oop(), "expected an oop"); |
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6682 HeapWord* addr = (HeapWord*)obj; |
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6683 if (_span.contains(addr)) { |
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6684 // this should be made more efficient |
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6685 _bitMap->mark(addr); |
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6686 } |
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6687 } |
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6688 |
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|
6689 void MarkRefsIntoClosure::do_oop(oop* p) { MarkRefsIntoClosure::do_oop_work(p); } |
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6690 void MarkRefsIntoClosure::do_oop(narrowOop* p) { MarkRefsIntoClosure::do_oop_work(p); } |
| 0 | 6691 |
| 6692 // A variant of the above, used for CMS marking verification. | |
| 6693 MarkRefsIntoVerifyClosure::MarkRefsIntoVerifyClosure( | |
|
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6694 MemRegion span, CMSBitMap* verification_bm, CMSBitMap* cms_bm): |
| 0 | 6695 _span(span), |
| 6696 _verification_bm(verification_bm), | |
|
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6697 _cms_bm(cms_bm) |
|
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|
6698 { |
| 0 | 6699 assert(_ref_processor == NULL, "deliberately left NULL"); |
| 6700 assert(_verification_bm->covers(_span), "_verification_bm/_span mismatch"); | |
| 6701 } | |
| 6702 | |
|
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6703 void MarkRefsIntoVerifyClosure::do_oop(oop obj) { |
| 0 | 6704 // if p points into _span, then mark corresponding bit in _markBitMap |
|
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6705 assert(obj->is_oop(), "expected an oop"); |
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6706 HeapWord* addr = (HeapWord*)obj; |
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6707 if (_span.contains(addr)) { |
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6708 _verification_bm->mark(addr); |
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6709 if (!_cms_bm->isMarked(addr)) { |
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|
6710 oop(addr)->print(); |
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6711 gclog_or_tty->print_cr(" (" INTPTR_FORMAT " should have been marked)", addr); |
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6712 fatal("... aborting"); |
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|
6713 } |
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|
6714 } |
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|
6715 } |
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6716 |
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|
6717 void MarkRefsIntoVerifyClosure::do_oop(oop* p) { MarkRefsIntoVerifyClosure::do_oop_work(p); } |
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6718 void MarkRefsIntoVerifyClosure::do_oop(narrowOop* p) { MarkRefsIntoVerifyClosure::do_oop_work(p); } |
| 0 | 6719 |
| 6720 ////////////////////////////////////////////////// | |
| 6721 // MarkRefsIntoAndScanClosure | |
| 6722 ////////////////////////////////////////////////// | |
| 6723 | |
| 6724 MarkRefsIntoAndScanClosure::MarkRefsIntoAndScanClosure(MemRegion span, | |
| 6725 ReferenceProcessor* rp, | |
| 6726 CMSBitMap* bit_map, | |
| 6727 CMSBitMap* mod_union_table, | |
| 6728 CMSMarkStack* mark_stack, | |
| 6729 CMSCollector* collector, | |
| 6730 bool should_yield, | |
| 6731 bool concurrent_precleaning): | |
| 6732 _collector(collector), | |
| 6733 _span(span), | |
| 6734 _bit_map(bit_map), | |
| 6735 _mark_stack(mark_stack), | |
| 6736 _pushAndMarkClosure(collector, span, rp, bit_map, mod_union_table, | |
|
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6737 mark_stack, concurrent_precleaning), |
| 0 | 6738 _yield(should_yield), |
| 6739 _concurrent_precleaning(concurrent_precleaning), | |
| 6740 _freelistLock(NULL) | |
| 6741 { | |
| 6742 _ref_processor = rp; | |
| 6743 assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL"); | |
| 6744 } | |
| 6745 | |
| 6746 // This closure is used to mark refs into the CMS generation at the | |
| 6747 // second (final) checkpoint, and to scan and transitively follow | |
| 6748 // the unmarked oops. It is also used during the concurrent precleaning | |
| 6749 // phase while scanning objects on dirty cards in the CMS generation. | |
| 6750 // The marks are made in the marking bit map and the marking stack is | |
| 6751 // used for keeping the (newly) grey objects during the scan. | |
| 6752 // The parallel version (Par_...) appears further below. | |
|
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6753 void MarkRefsIntoAndScanClosure::do_oop(oop obj) { |
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6754 if (obj != NULL) { |
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6755 assert(obj->is_oop(), "expected an oop"); |
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6756 HeapWord* addr = (HeapWord*)obj; |
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6757 assert(_mark_stack->isEmpty(), "pre-condition (eager drainage)"); |
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6758 assert(_collector->overflow_list_is_empty(), |
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6759 "overflow list should be empty"); |
| 0 | 6760 if (_span.contains(addr) && |
| 6761 !_bit_map->isMarked(addr)) { | |
| 6762 // mark bit map (object is now grey) | |
| 6763 _bit_map->mark(addr); | |
| 6764 // push on marking stack (stack should be empty), and drain the | |
| 6765 // stack by applying this closure to the oops in the oops popped | |
| 6766 // from the stack (i.e. blacken the grey objects) | |
|
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6767 bool res = _mark_stack->push(obj); |
| 0 | 6768 assert(res, "Should have space to push on empty stack"); |
| 6769 do { | |
| 6770 oop new_oop = _mark_stack->pop(); | |
| 6771 assert(new_oop != NULL && new_oop->is_oop(), "Expected an oop"); | |
| 6772 assert(_bit_map->isMarked((HeapWord*)new_oop), | |
| 6773 "only grey objects on this stack"); | |
| 6774 // iterate over the oops in this oop, marking and pushing | |
| 6775 // the ones in CMS heap (i.e. in _span). | |
| 6776 new_oop->oop_iterate(&_pushAndMarkClosure); | |
| 6777 // check if it's time to yield | |
| 6778 do_yield_check(); | |
| 6779 } while (!_mark_stack->isEmpty() || | |
| 6780 (!_concurrent_precleaning && take_from_overflow_list())); | |
| 6781 // if marking stack is empty, and we are not doing this | |
| 6782 // during precleaning, then check the overflow list | |
| 6783 } | |
| 6784 assert(_mark_stack->isEmpty(), "post-condition (eager drainage)"); | |
| 6785 assert(_collector->overflow_list_is_empty(), | |
| 6786 "overflow list was drained above"); | |
| 6787 // We could restore evacuated mark words, if any, used for | |
| 6788 // overflow list links here because the overflow list is | |
| 6789 // provably empty here. That would reduce the maximum | |
| 6790 // size requirements for preserved_{oop,mark}_stack. | |
| 6791 // But we'll just postpone it until we are all done | |
| 6792 // so we can just stream through. | |
| 6793 if (!_concurrent_precleaning && CMSOverflowEarlyRestoration) { | |
| 6794 _collector->restore_preserved_marks_if_any(); | |
| 6795 assert(_collector->no_preserved_marks(), "No preserved marks"); | |
| 6796 } | |
| 6797 assert(!CMSOverflowEarlyRestoration || _collector->no_preserved_marks(), | |
| 6798 "All preserved marks should have been restored above"); | |
| 6799 } | |
| 6800 } | |
| 6801 | |
|
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6802 void MarkRefsIntoAndScanClosure::do_oop(oop* p) { MarkRefsIntoAndScanClosure::do_oop_work(p); } |
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6803 void MarkRefsIntoAndScanClosure::do_oop(narrowOop* p) { MarkRefsIntoAndScanClosure::do_oop_work(p); } |
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6804 |
| 0 | 6805 void MarkRefsIntoAndScanClosure::do_yield_work() { |
| 6806 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 6807 "CMS thread should hold CMS token"); | |
| 6808 assert_lock_strong(_freelistLock); | |
| 6809 assert_lock_strong(_bit_map->lock()); | |
| 6810 // relinquish the free_list_lock and bitMaplock() | |
| 6811 _bit_map->lock()->unlock(); | |
| 6812 _freelistLock->unlock(); | |
| 6813 ConcurrentMarkSweepThread::desynchronize(true); | |
| 6814 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 6815 _collector->stopTimer(); | |
| 6816 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 6817 if (PrintCMSStatistics != 0) { | |
| 6818 _collector->incrementYields(); | |
| 6819 } | |
| 6820 _collector->icms_wait(); | |
| 6821 | |
| 6822 // See the comment in coordinator_yield() | |
|
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6823 for (unsigned i = 0; |
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6824 i < CMSYieldSleepCount && |
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6825 ConcurrentMarkSweepThread::should_yield() && |
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6826 !CMSCollector::foregroundGCIsActive(); |
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6827 ++i) { |
| 0 | 6828 os::sleep(Thread::current(), 1, false); |
| 6829 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 6830 } | |
| 6831 | |
| 6832 ConcurrentMarkSweepThread::synchronize(true); | |
| 6833 _freelistLock->lock_without_safepoint_check(); | |
| 6834 _bit_map->lock()->lock_without_safepoint_check(); | |
| 6835 _collector->startTimer(); | |
| 6836 } | |
| 6837 | |
| 6838 /////////////////////////////////////////////////////////// | |
| 6839 // Par_MarkRefsIntoAndScanClosure: a parallel version of | |
| 6840 // MarkRefsIntoAndScanClosure | |
| 6841 /////////////////////////////////////////////////////////// | |
| 6842 Par_MarkRefsIntoAndScanClosure::Par_MarkRefsIntoAndScanClosure( | |
| 6843 CMSCollector* collector, MemRegion span, ReferenceProcessor* rp, | |
|
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6844 CMSBitMap* bit_map, OopTaskQueue* work_queue): |
| 0 | 6845 _span(span), |
| 6846 _bit_map(bit_map), | |
| 6847 _work_queue(work_queue), | |
| 6848 _low_water_mark(MIN2((uint)(work_queue->max_elems()/4), | |
| 6849 (uint)(CMSWorkQueueDrainThreshold * ParallelGCThreads))), | |
|
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6850 _par_pushAndMarkClosure(collector, span, rp, bit_map, work_queue) |
| 0 | 6851 { |
| 6852 _ref_processor = rp; | |
| 6853 assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL"); | |
| 6854 } | |
| 6855 | |
| 6856 // This closure is used to mark refs into the CMS generation at the | |
| 6857 // second (final) checkpoint, and to scan and transitively follow | |
| 6858 // the unmarked oops. The marks are made in the marking bit map and | |
| 6859 // the work_queue is used for keeping the (newly) grey objects during | |
| 6860 // the scan phase whence they are also available for stealing by parallel | |
| 6861 // threads. Since the marking bit map is shared, updates are | |
| 6862 // synchronized (via CAS). | |
|
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6863 void Par_MarkRefsIntoAndScanClosure::do_oop(oop obj) { |
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6864 if (obj != NULL) { |
| 0 | 6865 // Ignore mark word because this could be an already marked oop |
| 6866 // that may be chained at the end of the overflow list. | |
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6867 assert(obj->is_oop(true), "expected an oop"); |
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6868 HeapWord* addr = (HeapWord*)obj; |
| 0 | 6869 if (_span.contains(addr) && |
| 6870 !_bit_map->isMarked(addr)) { | |
| 6871 // mark bit map (object will become grey): | |
| 6872 // It is possible for several threads to be | |
| 6873 // trying to "claim" this object concurrently; | |
| 6874 // the unique thread that succeeds in marking the | |
| 6875 // object first will do the subsequent push on | |
| 6876 // to the work queue (or overflow list). | |
| 6877 if (_bit_map->par_mark(addr)) { | |
| 6878 // push on work_queue (which may not be empty), and trim the | |
| 6879 // queue to an appropriate length by applying this closure to | |
| 6880 // the oops in the oops popped from the stack (i.e. blacken the | |
| 6881 // grey objects) | |
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6882 bool res = _work_queue->push(obj); |
| 0 | 6883 assert(res, "Low water mark should be less than capacity?"); |
| 6884 trim_queue(_low_water_mark); | |
| 6885 } // Else, another thread claimed the object | |
| 6886 } | |
| 6887 } | |
| 6888 } | |
| 6889 | |
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6890 void Par_MarkRefsIntoAndScanClosure::do_oop(oop* p) { Par_MarkRefsIntoAndScanClosure::do_oop_work(p); } |
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6891 void Par_MarkRefsIntoAndScanClosure::do_oop(narrowOop* p) { Par_MarkRefsIntoAndScanClosure::do_oop_work(p); } |
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6892 |
| 0 | 6893 // This closure is used to rescan the marked objects on the dirty cards |
| 6894 // in the mod union table and the card table proper. | |
| 6895 size_t ScanMarkedObjectsAgainCarefullyClosure::do_object_careful_m( | |
| 6896 oop p, MemRegion mr) { | |
| 6897 | |
| 6898 size_t size = 0; | |
| 6899 HeapWord* addr = (HeapWord*)p; | |
| 6900 DEBUG_ONLY(_collector->verify_work_stacks_empty();) | |
| 6901 assert(_span.contains(addr), "we are scanning the CMS generation"); | |
| 6902 // check if it's time to yield | |
| 6903 if (do_yield_check()) { | |
| 6904 // We yielded for some foreground stop-world work, | |
| 6905 // and we have been asked to abort this ongoing preclean cycle. | |
| 6906 return 0; | |
| 6907 } | |
| 6908 if (_bitMap->isMarked(addr)) { | |
| 6909 // it's marked; is it potentially uninitialized? | |
| 187 | 6910 if (p->klass_or_null() != NULL) { |
| 0 | 6911 // an initialized object; ignore mark word in verification below |
| 6912 // since we are running concurrent with mutators | |
| 6913 assert(p->is_oop(true), "should be an oop"); | |
| 6914 if (p->is_objArray()) { | |
| 6915 // objArrays are precisely marked; restrict scanning | |
| 6916 // to dirty cards only. | |
| 187 | 6917 size = CompactibleFreeListSpace::adjustObjectSize( |
| 6918 p->oop_iterate(_scanningClosure, mr)); | |
| 0 | 6919 } else { |
| 6920 // A non-array may have been imprecisely marked; we need | |
| 6921 // to scan object in its entirety. | |
| 6922 size = CompactibleFreeListSpace::adjustObjectSize( | |
| 6923 p->oop_iterate(_scanningClosure)); | |
| 6924 } | |
| 9152 | 6925 #ifdef ASSERT |
| 0 | 6926 size_t direct_size = |
| 6927 CompactibleFreeListSpace::adjustObjectSize(p->size()); | |
| 6928 assert(size == direct_size, "Inconsistency in size"); | |
| 6929 assert(size >= 3, "Necessary for Printezis marks to work"); | |
| 6930 if (!_bitMap->isMarked(addr+1)) { | |
| 6931 _bitMap->verifyNoOneBitsInRange(addr+2, addr+size); | |
| 6932 } else { | |
| 6933 _bitMap->verifyNoOneBitsInRange(addr+2, addr+size-1); | |
| 6934 assert(_bitMap->isMarked(addr+size-1), | |
| 6935 "inconsistent Printezis mark"); | |
| 6936 } | |
| 9152 | 6937 #endif // ASSERT |
| 0 | 6938 } else { |
| 6939 // an unitialized object | |
| 6940 assert(_bitMap->isMarked(addr+1), "missing Printezis mark?"); | |
| 6941 HeapWord* nextOneAddr = _bitMap->getNextMarkedWordAddress(addr + 2); | |
| 6942 size = pointer_delta(nextOneAddr + 1, addr); | |
| 6943 assert(size == CompactibleFreeListSpace::adjustObjectSize(size), | |
| 6944 "alignment problem"); | |
| 6945 // Note that pre-cleaning needn't redirty the card. OopDesc::set_klass() | |
| 6946 // will dirty the card when the klass pointer is installed in the | |
| 6947 // object (signalling the completion of initialization). | |
| 6948 } | |
| 6949 } else { | |
| 6950 // Either a not yet marked object or an uninitialized object | |
|
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6951 if (p->klass_or_null() == NULL) { |
| 0 | 6952 // An uninitialized object, skip to the next card, since |
| 6953 // we may not be able to read its P-bits yet. | |
| 6954 assert(size == 0, "Initial value"); | |
| 6955 } else { | |
| 6956 // An object not (yet) reached by marking: we merely need to | |
| 6957 // compute its size so as to go look at the next block. | |
| 6958 assert(p->is_oop(true), "should be an oop"); | |
| 6959 size = CompactibleFreeListSpace::adjustObjectSize(p->size()); | |
| 6960 } | |
| 6961 } | |
| 6962 DEBUG_ONLY(_collector->verify_work_stacks_empty();) | |
| 6963 return size; | |
| 6964 } | |
| 6965 | |
| 6966 void ScanMarkedObjectsAgainCarefullyClosure::do_yield_work() { | |
| 6967 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 6968 "CMS thread should hold CMS token"); | |
| 6969 assert_lock_strong(_freelistLock); | |
| 6970 assert_lock_strong(_bitMap->lock()); | |
| 6971 // relinquish the free_list_lock and bitMaplock() | |
| 6972 _bitMap->lock()->unlock(); | |
| 6973 _freelistLock->unlock(); | |
| 6974 ConcurrentMarkSweepThread::desynchronize(true); | |
| 6975 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 6976 _collector->stopTimer(); | |
| 6977 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 6978 if (PrintCMSStatistics != 0) { | |
| 6979 _collector->incrementYields(); | |
| 6980 } | |
| 6981 _collector->icms_wait(); | |
| 6982 | |
| 6983 // See the comment in coordinator_yield() | |
| 6984 for (unsigned i = 0; i < CMSYieldSleepCount && | |
|
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6985 ConcurrentMarkSweepThread::should_yield() && |
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6986 !CMSCollector::foregroundGCIsActive(); ++i) { |
| 0 | 6987 os::sleep(Thread::current(), 1, false); |
| 6988 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 6989 } | |
| 6990 | |
| 6991 ConcurrentMarkSweepThread::synchronize(true); | |
| 6992 _freelistLock->lock_without_safepoint_check(); | |
| 6993 _bitMap->lock()->lock_without_safepoint_check(); | |
| 6994 _collector->startTimer(); | |
| 6995 } | |
| 6996 | |
| 6997 | |
| 6998 ////////////////////////////////////////////////////////////////// | |
| 6999 // SurvivorSpacePrecleanClosure | |
| 7000 ////////////////////////////////////////////////////////////////// | |
| 7001 // This (single-threaded) closure is used to preclean the oops in | |
| 7002 // the survivor spaces. | |
| 7003 size_t SurvivorSpacePrecleanClosure::do_object_careful(oop p) { | |
| 7004 | |
| 7005 HeapWord* addr = (HeapWord*)p; | |
| 7006 DEBUG_ONLY(_collector->verify_work_stacks_empty();) | |
| 7007 assert(!_span.contains(addr), "we are scanning the survivor spaces"); | |
| 187 | 7008 assert(p->klass_or_null() != NULL, "object should be initializd"); |
| 0 | 7009 // an initialized object; ignore mark word in verification below |
| 7010 // since we are running concurrent with mutators | |
| 7011 assert(p->is_oop(true), "should be an oop"); | |
| 7012 // Note that we do not yield while we iterate over | |
| 7013 // the interior oops of p, pushing the relevant ones | |
| 7014 // on our marking stack. | |
| 7015 size_t size = p->oop_iterate(_scanning_closure); | |
| 7016 do_yield_check(); | |
| 7017 // Observe that below, we do not abandon the preclean | |
| 7018 // phase as soon as we should; rather we empty the | |
| 7019 // marking stack before returning. This is to satisfy | |
| 7020 // some existing assertions. In general, it may be a | |
| 7021 // good idea to abort immediately and complete the marking | |
| 7022 // from the grey objects at a later time. | |
| 7023 while (!_mark_stack->isEmpty()) { | |
| 7024 oop new_oop = _mark_stack->pop(); | |
| 7025 assert(new_oop != NULL && new_oop->is_oop(), "Expected an oop"); | |
| 7026 assert(_bit_map->isMarked((HeapWord*)new_oop), | |
| 7027 "only grey objects on this stack"); | |
| 7028 // iterate over the oops in this oop, marking and pushing | |
| 7029 // the ones in CMS heap (i.e. in _span). | |
| 7030 new_oop->oop_iterate(_scanning_closure); | |
| 7031 // check if it's time to yield | |
| 7032 do_yield_check(); | |
| 7033 } | |
| 7034 unsigned int after_count = | |
| 7035 GenCollectedHeap::heap()->total_collections(); | |
| 7036 bool abort = (_before_count != after_count) || | |
| 7037 _collector->should_abort_preclean(); | |
| 7038 return abort ? 0 : size; | |
| 7039 } | |
| 7040 | |
| 7041 void SurvivorSpacePrecleanClosure::do_yield_work() { | |
| 7042 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 7043 "CMS thread should hold CMS token"); | |
| 7044 assert_lock_strong(_bit_map->lock()); | |
| 7045 // Relinquish the bit map lock | |
| 7046 _bit_map->lock()->unlock(); | |
| 7047 ConcurrentMarkSweepThread::desynchronize(true); | |
| 7048 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7049 _collector->stopTimer(); | |
| 7050 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 7051 if (PrintCMSStatistics != 0) { | |
| 7052 _collector->incrementYields(); | |
| 7053 } | |
| 7054 _collector->icms_wait(); | |
| 7055 | |
| 7056 // See the comment in coordinator_yield() | |
| 7057 for (unsigned i = 0; i < CMSYieldSleepCount && | |
| 7058 ConcurrentMarkSweepThread::should_yield() && | |
| 7059 !CMSCollector::foregroundGCIsActive(); ++i) { | |
| 7060 os::sleep(Thread::current(), 1, false); | |
| 7061 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7062 } | |
| 7063 | |
| 7064 ConcurrentMarkSweepThread::synchronize(true); | |
| 7065 _bit_map->lock()->lock_without_safepoint_check(); | |
| 7066 _collector->startTimer(); | |
| 7067 } | |
| 7068 | |
| 7069 // This closure is used to rescan the marked objects on the dirty cards | |
| 7070 // in the mod union table and the card table proper. In the parallel | |
| 7071 // case, although the bitMap is shared, we do a single read so the | |
| 7072 // isMarked() query is "safe". | |
| 7073 bool ScanMarkedObjectsAgainClosure::do_object_bm(oop p, MemRegion mr) { | |
| 7074 // Ignore mark word because we are running concurrent with mutators | |
| 7075 assert(p->is_oop_or_null(true), "expected an oop or null"); | |
| 7076 HeapWord* addr = (HeapWord*)p; | |
| 7077 assert(_span.contains(addr), "we are scanning the CMS generation"); | |
| 7078 bool is_obj_array = false; | |
| 9152 | 7079 #ifdef ASSERT |
| 0 | 7080 if (!_parallel) { |
| 7081 assert(_mark_stack->isEmpty(), "pre-condition (eager drainage)"); | |
| 7082 assert(_collector->overflow_list_is_empty(), | |
| 7083 "overflow list should be empty"); | |
| 7084 | |
| 7085 } | |
| 9152 | 7086 #endif // ASSERT |
| 0 | 7087 if (_bit_map->isMarked(addr)) { |
| 7088 // Obj arrays are precisely marked, non-arrays are not; | |
| 7089 // so we scan objArrays precisely and non-arrays in their | |
| 7090 // entirety. | |
| 7091 if (p->is_objArray()) { | |
| 7092 is_obj_array = true; | |
| 7093 if (_parallel) { | |
| 7094 p->oop_iterate(_par_scan_closure, mr); | |
| 7095 } else { | |
| 7096 p->oop_iterate(_scan_closure, mr); | |
| 7097 } | |
| 7098 } else { | |
| 7099 if (_parallel) { | |
| 7100 p->oop_iterate(_par_scan_closure); | |
| 7101 } else { | |
| 7102 p->oop_iterate(_scan_closure); | |
| 7103 } | |
| 7104 } | |
| 7105 } | |
| 9152 | 7106 #ifdef ASSERT |
| 0 | 7107 if (!_parallel) { |
| 7108 assert(_mark_stack->isEmpty(), "post-condition (eager drainage)"); | |
| 7109 assert(_collector->overflow_list_is_empty(), | |
| 7110 "overflow list should be empty"); | |
| 7111 | |
| 7112 } | |
| 9152 | 7113 #endif // ASSERT |
| 0 | 7114 return is_obj_array; |
| 7115 } | |
| 7116 | |
| 7117 MarkFromRootsClosure::MarkFromRootsClosure(CMSCollector* collector, | |
| 7118 MemRegion span, | |
| 7119 CMSBitMap* bitMap, CMSMarkStack* markStack, | |
| 7120 bool should_yield, bool verifying): | |
| 7121 _collector(collector), | |
| 7122 _span(span), | |
| 7123 _bitMap(bitMap), | |
| 7124 _mut(&collector->_modUnionTable), | |
| 7125 _markStack(markStack), | |
| 7126 _yield(should_yield), | |
| 7127 _skipBits(0) | |
| 7128 { | |
| 7129 assert(_markStack->isEmpty(), "stack should be empty"); | |
| 7130 _finger = _bitMap->startWord(); | |
| 7131 _threshold = _finger; | |
| 7132 assert(_collector->_restart_addr == NULL, "Sanity check"); | |
| 7133 assert(_span.contains(_finger), "Out of bounds _finger?"); | |
| 7134 DEBUG_ONLY(_verifying = verifying;) | |
| 7135 } | |
| 7136 | |
| 7137 void MarkFromRootsClosure::reset(HeapWord* addr) { | |
| 7138 assert(_markStack->isEmpty(), "would cause duplicates on stack"); | |
| 7139 assert(_span.contains(addr), "Out of bounds _finger?"); | |
| 7140 _finger = addr; | |
| 7141 _threshold = (HeapWord*)round_to( | |
| 7142 (intptr_t)_finger, CardTableModRefBS::card_size); | |
| 7143 } | |
| 7144 | |
| 7145 // Should revisit to see if this should be restructured for | |
| 7146 // greater efficiency. | |
|
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7147 bool MarkFromRootsClosure::do_bit(size_t offset) { |
| 0 | 7148 if (_skipBits > 0) { |
| 7149 _skipBits--; | |
|
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7150 return true; |
| 0 | 7151 } |
| 7152 // convert offset into a HeapWord* | |
| 7153 HeapWord* addr = _bitMap->startWord() + offset; | |
| 7154 assert(_bitMap->endWord() && addr < _bitMap->endWord(), | |
| 7155 "address out of range"); | |
| 7156 assert(_bitMap->isMarked(addr), "tautology"); | |
| 7157 if (_bitMap->isMarked(addr+1)) { | |
| 7158 // this is an allocated but not yet initialized object | |
| 7159 assert(_skipBits == 0, "tautology"); | |
| 7160 _skipBits = 2; // skip next two marked bits ("Printezis-marks") | |
| 7161 oop p = oop(addr); | |
|
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7162 if (p->klass_or_null() == NULL) { |
| 0 | 7163 DEBUG_ONLY(if (!_verifying) {) |
| 7164 // We re-dirty the cards on which this object lies and increase | |
| 7165 // the _threshold so that we'll come back to scan this object | |
| 7166 // during the preclean or remark phase. (CMSCleanOnEnter) | |
| 7167 if (CMSCleanOnEnter) { | |
| 7168 size_t sz = _collector->block_size_using_printezis_bits(addr); | |
| 7169 HeapWord* end_card_addr = (HeapWord*)round_to( | |
| 7170 (intptr_t)(addr+sz), CardTableModRefBS::card_size); | |
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7171 MemRegion redirty_range = MemRegion(addr, end_card_addr); |
| 0 | 7172 assert(!redirty_range.is_empty(), "Arithmetical tautology"); |
| 7173 // Bump _threshold to end_card_addr; note that | |
| 7174 // _threshold cannot possibly exceed end_card_addr, anyhow. | |
| 7175 // This prevents future clearing of the card as the scan proceeds | |
| 7176 // to the right. | |
| 7177 assert(_threshold <= end_card_addr, | |
| 7178 "Because we are just scanning into this object"); | |
| 7179 if (_threshold < end_card_addr) { | |
| 7180 _threshold = end_card_addr; | |
| 7181 } | |
| 187 | 7182 if (p->klass_or_null() != NULL) { |
| 0 | 7183 // Redirty the range of cards... |
| 7184 _mut->mark_range(redirty_range); | |
| 7185 } // ...else the setting of klass will dirty the card anyway. | |
| 7186 } | |
| 7187 DEBUG_ONLY(}) | |
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7188 return true; |
| 0 | 7189 } |
| 7190 } | |
| 7191 scanOopsInOop(addr); | |
|
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7192 return true; |
| 0 | 7193 } |
| 7194 | |
| 7195 // We take a break if we've been at this for a while, | |
| 7196 // so as to avoid monopolizing the locks involved. | |
| 7197 void MarkFromRootsClosure::do_yield_work() { | |
| 7198 // First give up the locks, then yield, then re-lock | |
| 7199 // We should probably use a constructor/destructor idiom to | |
| 7200 // do this unlock/lock or modify the MutexUnlocker class to | |
| 7201 // serve our purpose. XXX | |
| 7202 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 7203 "CMS thread should hold CMS token"); | |
| 7204 assert_lock_strong(_bitMap->lock()); | |
| 7205 _bitMap->lock()->unlock(); | |
| 7206 ConcurrentMarkSweepThread::desynchronize(true); | |
| 7207 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7208 _collector->stopTimer(); | |
| 7209 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 7210 if (PrintCMSStatistics != 0) { | |
| 7211 _collector->incrementYields(); | |
| 7212 } | |
| 7213 _collector->icms_wait(); | |
| 7214 | |
| 7215 // See the comment in coordinator_yield() | |
| 7216 for (unsigned i = 0; i < CMSYieldSleepCount && | |
| 7217 ConcurrentMarkSweepThread::should_yield() && | |
| 7218 !CMSCollector::foregroundGCIsActive(); ++i) { | |
| 7219 os::sleep(Thread::current(), 1, false); | |
| 7220 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7221 } | |
| 7222 | |
| 7223 ConcurrentMarkSweepThread::synchronize(true); | |
| 7224 _bitMap->lock()->lock_without_safepoint_check(); | |
| 7225 _collector->startTimer(); | |
| 7226 } | |
| 7227 | |
| 7228 void MarkFromRootsClosure::scanOopsInOop(HeapWord* ptr) { | |
| 7229 assert(_bitMap->isMarked(ptr), "expected bit to be set"); | |
| 7230 assert(_markStack->isEmpty(), | |
| 7231 "should drain stack to limit stack usage"); | |
| 7232 // convert ptr to an oop preparatory to scanning | |
|
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7233 oop obj = oop(ptr); |
| 0 | 7234 // Ignore mark word in verification below, since we |
| 7235 // may be running concurrent with mutators. | |
|
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7236 assert(obj->is_oop(true), "should be an oop"); |
| 0 | 7237 assert(_finger <= ptr, "_finger runneth ahead"); |
| 7238 // advance the finger to right end of this object | |
|
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7239 _finger = ptr + obj->size(); |
| 0 | 7240 assert(_finger > ptr, "we just incremented it above"); |
| 7241 // On large heaps, it may take us some time to get through | |
| 7242 // the marking phase (especially if running iCMS). During | |
| 7243 // this time it's possible that a lot of mutations have | |
| 7244 // accumulated in the card table and the mod union table -- | |
| 7245 // these mutation records are redundant until we have | |
| 7246 // actually traced into the corresponding card. | |
| 7247 // Here, we check whether advancing the finger would make | |
| 7248 // us cross into a new card, and if so clear corresponding | |
| 7249 // cards in the MUT (preclean them in the card-table in the | |
| 7250 // future). | |
| 7251 | |
| 7252 DEBUG_ONLY(if (!_verifying) {) | |
| 7253 // The clean-on-enter optimization is disabled by default, | |
| 7254 // until we fix 6178663. | |
| 7255 if (CMSCleanOnEnter && (_finger > _threshold)) { | |
| 7256 // [_threshold, _finger) represents the interval | |
| 7257 // of cards to be cleared in MUT (or precleaned in card table). | |
| 7258 // The set of cards to be cleared is all those that overlap | |
| 7259 // with the interval [_threshold, _finger); note that | |
| 7260 // _threshold is always kept card-aligned but _finger isn't | |
| 7261 // always card-aligned. | |
| 7262 HeapWord* old_threshold = _threshold; | |
| 7263 assert(old_threshold == (HeapWord*)round_to( | |
| 7264 (intptr_t)old_threshold, CardTableModRefBS::card_size), | |
| 7265 "_threshold should always be card-aligned"); | |
| 7266 _threshold = (HeapWord*)round_to( | |
| 7267 (intptr_t)_finger, CardTableModRefBS::card_size); | |
| 7268 MemRegion mr(old_threshold, _threshold); | |
| 7269 assert(!mr.is_empty(), "Control point invariant"); | |
| 7270 assert(_span.contains(mr), "Should clear within span"); | |
| 7271 _mut->clear_range(mr); | |
| 7272 } | |
| 7273 DEBUG_ONLY(}) | |
| 7274 // Note: the finger doesn't advance while we drain | |
| 7275 // the stack below. | |
| 7276 PushOrMarkClosure pushOrMarkClosure(_collector, | |
| 7277 _span, _bitMap, _markStack, | |
| 7278 _finger, this); | |
|
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7279 bool res = _markStack->push(obj); |
| 0 | 7280 assert(res, "Empty non-zero size stack should have space for single push"); |
| 7281 while (!_markStack->isEmpty()) { | |
| 7282 oop new_oop = _markStack->pop(); | |
| 7283 // Skip verifying header mark word below because we are | |
| 7284 // running concurrent with mutators. | |
| 7285 assert(new_oop->is_oop(true), "Oops! expected to pop an oop"); | |
| 7286 // now scan this oop's oops | |
| 7287 new_oop->oop_iterate(&pushOrMarkClosure); | |
| 7288 do_yield_check(); | |
| 7289 } | |
| 7290 assert(_markStack->isEmpty(), "tautology, emphasizing post-condition"); | |
| 7291 } | |
| 7292 | |
| 7293 Par_MarkFromRootsClosure::Par_MarkFromRootsClosure(CMSConcMarkingTask* task, | |
| 7294 CMSCollector* collector, MemRegion span, | |
| 7295 CMSBitMap* bit_map, | |
| 7296 OopTaskQueue* work_queue, | |
| 7297 CMSMarkStack* overflow_stack, | |
| 7298 bool should_yield): | |
| 7299 _collector(collector), | |
| 7300 _whole_span(collector->_span), | |
| 7301 _span(span), | |
| 7302 _bit_map(bit_map), | |
| 7303 _mut(&collector->_modUnionTable), | |
| 7304 _work_queue(work_queue), | |
| 7305 _overflow_stack(overflow_stack), | |
| 7306 _yield(should_yield), | |
| 7307 _skip_bits(0), | |
| 7308 _task(task) | |
| 7309 { | |
| 7310 assert(_work_queue->size() == 0, "work_queue should be empty"); | |
| 7311 _finger = span.start(); | |
| 7312 _threshold = _finger; // XXX Defer clear-on-enter optimization for now | |
| 7313 assert(_span.contains(_finger), "Out of bounds _finger?"); | |
| 7314 } | |
| 7315 | |
| 7316 // Should revisit to see if this should be restructured for | |
| 7317 // greater efficiency. | |
|
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7318 bool Par_MarkFromRootsClosure::do_bit(size_t offset) { |
| 0 | 7319 if (_skip_bits > 0) { |
| 7320 _skip_bits--; | |
|
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7321 return true; |
| 0 | 7322 } |
| 7323 // convert offset into a HeapWord* | |
| 7324 HeapWord* addr = _bit_map->startWord() + offset; | |
| 7325 assert(_bit_map->endWord() && addr < _bit_map->endWord(), | |
| 7326 "address out of range"); | |
| 7327 assert(_bit_map->isMarked(addr), "tautology"); | |
| 7328 if (_bit_map->isMarked(addr+1)) { | |
| 7329 // this is an allocated object that might not yet be initialized | |
| 7330 assert(_skip_bits == 0, "tautology"); | |
| 7331 _skip_bits = 2; // skip next two marked bits ("Printezis-marks") | |
| 7332 oop p = oop(addr); | |
|
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7333 if (p->klass_or_null() == NULL) { |
| 0 | 7334 // in the case of Clean-on-Enter optimization, redirty card |
| 7335 // and avoid clearing card by increasing the threshold. | |
|
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7336 return true; |
| 0 | 7337 } |
| 7338 } | |
| 7339 scan_oops_in_oop(addr); | |
|
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7340 return true; |
| 0 | 7341 } |
| 7342 | |
| 7343 void Par_MarkFromRootsClosure::scan_oops_in_oop(HeapWord* ptr) { | |
| 7344 assert(_bit_map->isMarked(ptr), "expected bit to be set"); | |
| 7345 // Should we assert that our work queue is empty or | |
| 7346 // below some drain limit? | |
| 7347 assert(_work_queue->size() == 0, | |
| 7348 "should drain stack to limit stack usage"); | |
| 7349 // convert ptr to an oop preparatory to scanning | |
|
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7350 oop obj = oop(ptr); |
| 0 | 7351 // Ignore mark word in verification below, since we |
| 7352 // may be running concurrent with mutators. | |
|
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7353 assert(obj->is_oop(true), "should be an oop"); |
| 0 | 7354 assert(_finger <= ptr, "_finger runneth ahead"); |
| 7355 // advance the finger to right end of this object | |
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7356 _finger = ptr + obj->size(); |
| 0 | 7357 assert(_finger > ptr, "we just incremented it above"); |
| 7358 // On large heaps, it may take us some time to get through | |
| 7359 // the marking phase (especially if running iCMS). During | |
| 7360 // this time it's possible that a lot of mutations have | |
| 7361 // accumulated in the card table and the mod union table -- | |
| 7362 // these mutation records are redundant until we have | |
| 7363 // actually traced into the corresponding card. | |
| 7364 // Here, we check whether advancing the finger would make | |
| 7365 // us cross into a new card, and if so clear corresponding | |
| 7366 // cards in the MUT (preclean them in the card-table in the | |
| 7367 // future). | |
| 7368 | |
| 7369 // The clean-on-enter optimization is disabled by default, | |
| 7370 // until we fix 6178663. | |
| 7371 if (CMSCleanOnEnter && (_finger > _threshold)) { | |
| 7372 // [_threshold, _finger) represents the interval | |
| 7373 // of cards to be cleared in MUT (or precleaned in card table). | |
| 7374 // The set of cards to be cleared is all those that overlap | |
| 7375 // with the interval [_threshold, _finger); note that | |
| 7376 // _threshold is always kept card-aligned but _finger isn't | |
| 7377 // always card-aligned. | |
| 7378 HeapWord* old_threshold = _threshold; | |
| 7379 assert(old_threshold == (HeapWord*)round_to( | |
| 7380 (intptr_t)old_threshold, CardTableModRefBS::card_size), | |
| 7381 "_threshold should always be card-aligned"); | |
| 7382 _threshold = (HeapWord*)round_to( | |
| 7383 (intptr_t)_finger, CardTableModRefBS::card_size); | |
| 7384 MemRegion mr(old_threshold, _threshold); | |
| 7385 assert(!mr.is_empty(), "Control point invariant"); | |
| 7386 assert(_span.contains(mr), "Should clear within span"); // _whole_span ?? | |
| 7387 _mut->clear_range(mr); | |
| 7388 } | |
| 7389 | |
| 7390 // Note: the local finger doesn't advance while we drain | |
| 7391 // the stack below, but the global finger sure can and will. | |
| 7392 HeapWord** gfa = _task->global_finger_addr(); | |
| 7393 Par_PushOrMarkClosure pushOrMarkClosure(_collector, | |
| 7394 _span, _bit_map, | |
| 7395 _work_queue, | |
| 7396 _overflow_stack, | |
| 7397 _finger, | |
| 7398 gfa, this); | |
|
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7399 bool res = _work_queue->push(obj); // overflow could occur here |
| 0 | 7400 assert(res, "Will hold once we use workqueues"); |
| 7401 while (true) { | |
| 7402 oop new_oop; | |
| 7403 if (!_work_queue->pop_local(new_oop)) { | |
| 7404 // We emptied our work_queue; check if there's stuff that can | |
| 7405 // be gotten from the overflow stack. | |
| 7406 if (CMSConcMarkingTask::get_work_from_overflow_stack( | |
| 7407 _overflow_stack, _work_queue)) { | |
| 7408 do_yield_check(); | |
| 7409 continue; | |
| 7410 } else { // done | |
| 7411 break; | |
| 7412 } | |
| 7413 } | |
| 7414 // Skip verifying header mark word below because we are | |
| 7415 // running concurrent with mutators. | |
| 7416 assert(new_oop->is_oop(true), "Oops! expected to pop an oop"); | |
| 7417 // now scan this oop's oops | |
| 7418 new_oop->oop_iterate(&pushOrMarkClosure); | |
| 7419 do_yield_check(); | |
| 7420 } | |
| 7421 assert(_work_queue->size() == 0, "tautology, emphasizing post-condition"); | |
| 7422 } | |
| 7423 | |
| 7424 // Yield in response to a request from VM Thread or | |
| 7425 // from mutators. | |
| 7426 void Par_MarkFromRootsClosure::do_yield_work() { | |
| 7427 assert(_task != NULL, "sanity"); | |
| 7428 _task->yield(); | |
| 7429 } | |
| 7430 | |
| 7431 // A variant of the above used for verifying CMS marking work. | |
| 7432 MarkFromRootsVerifyClosure::MarkFromRootsVerifyClosure(CMSCollector* collector, | |
| 7433 MemRegion span, | |
| 7434 CMSBitMap* verification_bm, CMSBitMap* cms_bm, | |
| 7435 CMSMarkStack* mark_stack): | |
| 7436 _collector(collector), | |
| 7437 _span(span), | |
| 7438 _verification_bm(verification_bm), | |
| 7439 _cms_bm(cms_bm), | |
| 7440 _mark_stack(mark_stack), | |
| 7441 _pam_verify_closure(collector, span, verification_bm, cms_bm, | |
| 7442 mark_stack) | |
| 7443 { | |
| 7444 assert(_mark_stack->isEmpty(), "stack should be empty"); | |
| 7445 _finger = _verification_bm->startWord(); | |
| 7446 assert(_collector->_restart_addr == NULL, "Sanity check"); | |
| 7447 assert(_span.contains(_finger), "Out of bounds _finger?"); | |
| 7448 } | |
| 7449 | |
| 7450 void MarkFromRootsVerifyClosure::reset(HeapWord* addr) { | |
| 7451 assert(_mark_stack->isEmpty(), "would cause duplicates on stack"); | |
| 7452 assert(_span.contains(addr), "Out of bounds _finger?"); | |
| 7453 _finger = addr; | |
| 7454 } | |
| 7455 | |
| 7456 // Should revisit to see if this should be restructured for | |
| 7457 // greater efficiency. | |
|
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7458 bool MarkFromRootsVerifyClosure::do_bit(size_t offset) { |
| 0 | 7459 // convert offset into a HeapWord* |
| 7460 HeapWord* addr = _verification_bm->startWord() + offset; | |
| 7461 assert(_verification_bm->endWord() && addr < _verification_bm->endWord(), | |
| 7462 "address out of range"); | |
| 7463 assert(_verification_bm->isMarked(addr), "tautology"); | |
| 7464 assert(_cms_bm->isMarked(addr), "tautology"); | |
| 7465 | |
| 7466 assert(_mark_stack->isEmpty(), | |
| 7467 "should drain stack to limit stack usage"); | |
| 7468 // convert addr to an oop preparatory to scanning | |
|
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7469 oop obj = oop(addr); |
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7470 assert(obj->is_oop(), "should be an oop"); |
| 0 | 7471 assert(_finger <= addr, "_finger runneth ahead"); |
| 7472 // advance the finger to right end of this object | |
|
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7473 _finger = addr + obj->size(); |
| 0 | 7474 assert(_finger > addr, "we just incremented it above"); |
| 7475 // Note: the finger doesn't advance while we drain | |
| 7476 // the stack below. | |
|
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7477 bool res = _mark_stack->push(obj); |
| 0 | 7478 assert(res, "Empty non-zero size stack should have space for single push"); |
| 7479 while (!_mark_stack->isEmpty()) { | |
| 7480 oop new_oop = _mark_stack->pop(); | |
| 7481 assert(new_oop->is_oop(), "Oops! expected to pop an oop"); | |
| 7482 // now scan this oop's oops | |
| 7483 new_oop->oop_iterate(&_pam_verify_closure); | |
| 7484 } | |
| 7485 assert(_mark_stack->isEmpty(), "tautology, emphasizing post-condition"); | |
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7486 return true; |
| 0 | 7487 } |
| 7488 | |
| 7489 PushAndMarkVerifyClosure::PushAndMarkVerifyClosure( | |
| 7490 CMSCollector* collector, MemRegion span, | |
| 7491 CMSBitMap* verification_bm, CMSBitMap* cms_bm, | |
| 7492 CMSMarkStack* mark_stack): | |
|
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7493 CMSOopClosure(collector->ref_processor()), |
| 0 | 7494 _collector(collector), |
| 7495 _span(span), | |
| 7496 _verification_bm(verification_bm), | |
| 7497 _cms_bm(cms_bm), | |
| 7498 _mark_stack(mark_stack) | |
| 7499 { } | |
| 7500 | |
|
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7501 void PushAndMarkVerifyClosure::do_oop(oop* p) { PushAndMarkVerifyClosure::do_oop_work(p); } |
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7502 void PushAndMarkVerifyClosure::do_oop(narrowOop* p) { PushAndMarkVerifyClosure::do_oop_work(p); } |
| 0 | 7503 |
| 7504 // Upon stack overflow, we discard (part of) the stack, | |
| 7505 // remembering the least address amongst those discarded | |
| 7506 // in CMSCollector's _restart_address. | |
| 7507 void PushAndMarkVerifyClosure::handle_stack_overflow(HeapWord* lost) { | |
| 7508 // Remember the least grey address discarded | |
| 7509 HeapWord* ra = (HeapWord*)_mark_stack->least_value(lost); | |
| 7510 _collector->lower_restart_addr(ra); | |
| 7511 _mark_stack->reset(); // discard stack contents | |
| 7512 _mark_stack->expand(); // expand the stack if possible | |
| 7513 } | |
| 7514 | |
|
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7515 void PushAndMarkVerifyClosure::do_oop(oop obj) { |
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7516 assert(obj->is_oop_or_null(), "expected an oop or NULL"); |
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7517 HeapWord* addr = (HeapWord*)obj; |
| 0 | 7518 if (_span.contains(addr) && !_verification_bm->isMarked(addr)) { |
| 7519 // Oop lies in _span and isn't yet grey or black | |
| 7520 _verification_bm->mark(addr); // now grey | |
| 7521 if (!_cms_bm->isMarked(addr)) { | |
| 7522 oop(addr)->print(); | |
|
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7523 gclog_or_tty->print_cr(" (" INTPTR_FORMAT " should have been marked)", |
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7524 addr); |
| 0 | 7525 fatal("... aborting"); |
| 7526 } | |
| 7527 | |
|
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7528 if (!_mark_stack->push(obj)) { // stack overflow |
| 0 | 7529 if (PrintCMSStatistics != 0) { |
| 7530 gclog_or_tty->print_cr("CMS marking stack overflow (benign) at " | |
| 7531 SIZE_FORMAT, _mark_stack->capacity()); | |
| 7532 } | |
| 7533 assert(_mark_stack->isFull(), "Else push should have succeeded"); | |
| 7534 handle_stack_overflow(addr); | |
| 7535 } | |
| 7536 // anything including and to the right of _finger | |
| 7537 // will be scanned as we iterate over the remainder of the | |
| 7538 // bit map | |
| 7539 } | |
| 7540 } | |
| 7541 | |
| 7542 PushOrMarkClosure::PushOrMarkClosure(CMSCollector* collector, | |
| 7543 MemRegion span, | |
| 7544 CMSBitMap* bitMap, CMSMarkStack* markStack, | |
| 7545 HeapWord* finger, MarkFromRootsClosure* parent) : | |
|
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7546 CMSOopClosure(collector->ref_processor()), |
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7547 _collector(collector), |
| 0 | 7548 _span(span), |
| 7549 _bitMap(bitMap), | |
| 7550 _markStack(markStack), | |
| 7551 _finger(finger), | |
| 935 | 7552 _parent(parent) |
| 0 | 7553 { } |
| 7554 | |
| 7555 Par_PushOrMarkClosure::Par_PushOrMarkClosure(CMSCollector* collector, | |
| 7556 MemRegion span, | |
| 7557 CMSBitMap* bit_map, | |
| 7558 OopTaskQueue* work_queue, | |
| 7559 CMSMarkStack* overflow_stack, | |
| 7560 HeapWord* finger, | |
| 7561 HeapWord** global_finger_addr, | |
| 7562 Par_MarkFromRootsClosure* parent) : | |
|
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7563 CMSOopClosure(collector->ref_processor()), |
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7564 _collector(collector), |
| 0 | 7565 _whole_span(collector->_span), |
| 7566 _span(span), | |
| 7567 _bit_map(bit_map), | |
| 7568 _work_queue(work_queue), | |
| 7569 _overflow_stack(overflow_stack), | |
| 7570 _finger(finger), | |
| 7571 _global_finger_addr(global_finger_addr), | |
| 935 | 7572 _parent(parent) |
| 0 | 7573 { } |
| 7574 | |
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7575 // Assumes thread-safe access by callers, who are |
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7576 // responsible for mutual exclusion. |
| 0 | 7577 void CMSCollector::lower_restart_addr(HeapWord* low) { |
| 7578 assert(_span.contains(low), "Out of bounds addr"); | |
| 7579 if (_restart_addr == NULL) { | |
| 7580 _restart_addr = low; | |
| 7581 } else { | |
| 7582 _restart_addr = MIN2(_restart_addr, low); | |
| 7583 } | |
| 7584 } | |
| 7585 | |
| 7586 // Upon stack overflow, we discard (part of) the stack, | |
| 7587 // remembering the least address amongst those discarded | |
| 7588 // in CMSCollector's _restart_address. | |
| 7589 void PushOrMarkClosure::handle_stack_overflow(HeapWord* lost) { | |
| 7590 // Remember the least grey address discarded | |
| 7591 HeapWord* ra = (HeapWord*)_markStack->least_value(lost); | |
| 7592 _collector->lower_restart_addr(ra); | |
| 7593 _markStack->reset(); // discard stack contents | |
| 7594 _markStack->expand(); // expand the stack if possible | |
| 7595 } | |
| 7596 | |
| 7597 // Upon stack overflow, we discard (part of) the stack, | |
| 7598 // remembering the least address amongst those discarded | |
| 7599 // in CMSCollector's _restart_address. | |
| 7600 void Par_PushOrMarkClosure::handle_stack_overflow(HeapWord* lost) { | |
| 7601 // We need to do this under a mutex to prevent other | |
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7602 // workers from interfering with the work done below. |
| 0 | 7603 MutexLockerEx ml(_overflow_stack->par_lock(), |
| 7604 Mutex::_no_safepoint_check_flag); | |
| 7605 // Remember the least grey address discarded | |
| 7606 HeapWord* ra = (HeapWord*)_overflow_stack->least_value(lost); | |
| 7607 _collector->lower_restart_addr(ra); | |
| 7608 _overflow_stack->reset(); // discard stack contents | |
| 7609 _overflow_stack->expand(); // expand the stack if possible | |
| 7610 } | |
| 7611 | |
|
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7612 void CMKlassClosure::do_klass(Klass* k) { |
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7613 assert(_oop_closure != NULL, "Not initialized?"); |
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7614 k->oops_do(_oop_closure); |
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7615 } |
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7616 |
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7617 void PushOrMarkClosure::do_oop(oop obj) { |
| 0 | 7618 // Ignore mark word because we are running concurrent with mutators. |
|
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7619 assert(obj->is_oop_or_null(true), "expected an oop or NULL"); |
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7620 HeapWord* addr = (HeapWord*)obj; |
| 0 | 7621 if (_span.contains(addr) && !_bitMap->isMarked(addr)) { |
| 7622 // Oop lies in _span and isn't yet grey or black | |
| 7623 _bitMap->mark(addr); // now grey | |
| 7624 if (addr < _finger) { | |
| 7625 // the bit map iteration has already either passed, or | |
| 7626 // sampled, this bit in the bit map; we'll need to | |
| 7627 // use the marking stack to scan this oop's oops. | |
| 7628 bool simulate_overflow = false; | |
| 7629 NOT_PRODUCT( | |
| 7630 if (CMSMarkStackOverflowALot && | |
| 7631 _collector->simulate_overflow()) { | |
| 7632 // simulate a stack overflow | |
| 7633 simulate_overflow = true; | |
| 7634 } | |
| 7635 ) | |
|
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7636 if (simulate_overflow || !_markStack->push(obj)) { // stack overflow |
| 0 | 7637 if (PrintCMSStatistics != 0) { |
| 7638 gclog_or_tty->print_cr("CMS marking stack overflow (benign) at " | |
| 7639 SIZE_FORMAT, _markStack->capacity()); | |
| 7640 } | |
| 7641 assert(simulate_overflow || _markStack->isFull(), "Else push should have succeeded"); | |
| 7642 handle_stack_overflow(addr); | |
| 7643 } | |
| 7644 } | |
| 7645 // anything including and to the right of _finger | |
| 7646 // will be scanned as we iterate over the remainder of the | |
| 7647 // bit map | |
| 7648 do_yield_check(); | |
| 7649 } | |
| 7650 } | |
| 7651 | |
|
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7652 void PushOrMarkClosure::do_oop(oop* p) { PushOrMarkClosure::do_oop_work(p); } |
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7653 void PushOrMarkClosure::do_oop(narrowOop* p) { PushOrMarkClosure::do_oop_work(p); } |
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7654 |
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7655 void Par_PushOrMarkClosure::do_oop(oop obj) { |
| 0 | 7656 // Ignore mark word because we are running concurrent with mutators. |
|
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7657 assert(obj->is_oop_or_null(true), "expected an oop or NULL"); |
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7658 HeapWord* addr = (HeapWord*)obj; |
| 0 | 7659 if (_whole_span.contains(addr) && !_bit_map->isMarked(addr)) { |
| 7660 // Oop lies in _span and isn't yet grey or black | |
| 7661 // We read the global_finger (volatile read) strictly after marking oop | |
| 7662 bool res = _bit_map->par_mark(addr); // now grey | |
| 7663 volatile HeapWord** gfa = (volatile HeapWord**)_global_finger_addr; | |
| 7664 // Should we push this marked oop on our stack? | |
| 7665 // -- if someone else marked it, nothing to do | |
| 7666 // -- if target oop is above global finger nothing to do | |
| 7667 // -- if target oop is in chunk and above local finger | |
| 7668 // then nothing to do | |
| 7669 // -- else push on work queue | |
| 7670 if ( !res // someone else marked it, they will deal with it | |
| 7671 || (addr >= *gfa) // will be scanned in a later task | |
| 7672 || (_span.contains(addr) && addr >= _finger)) { // later in this chunk | |
| 7673 return; | |
| 7674 } | |
| 7675 // the bit map iteration has already either passed, or | |
| 7676 // sampled, this bit in the bit map; we'll need to | |
| 7677 // use the marking stack to scan this oop's oops. | |
| 7678 bool simulate_overflow = false; | |
| 7679 NOT_PRODUCT( | |
| 7680 if (CMSMarkStackOverflowALot && | |
| 7681 _collector->simulate_overflow()) { | |
| 7682 // simulate a stack overflow | |
| 7683 simulate_overflow = true; | |
| 7684 } | |
| 7685 ) | |
| 7686 if (simulate_overflow || | |
|
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7687 !(_work_queue->push(obj) || _overflow_stack->par_push(obj))) { |
| 0 | 7688 // stack overflow |
| 7689 if (PrintCMSStatistics != 0) { | |
| 7690 gclog_or_tty->print_cr("CMS marking stack overflow (benign) at " | |
| 7691 SIZE_FORMAT, _overflow_stack->capacity()); | |
| 7692 } | |
| 7693 // We cannot assert that the overflow stack is full because | |
| 7694 // it may have been emptied since. | |
| 7695 assert(simulate_overflow || | |
| 7696 _work_queue->size() == _work_queue->max_elems(), | |
| 7697 "Else push should have succeeded"); | |
| 7698 handle_stack_overflow(addr); | |
| 7699 } | |
| 7700 do_yield_check(); | |
| 7701 } | |
| 7702 } | |
| 7703 | |
|
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7704 void Par_PushOrMarkClosure::do_oop(oop* p) { Par_PushOrMarkClosure::do_oop_work(p); } |
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7705 void Par_PushOrMarkClosure::do_oop(narrowOop* p) { Par_PushOrMarkClosure::do_oop_work(p); } |
| 0 | 7706 |
| 7707 PushAndMarkClosure::PushAndMarkClosure(CMSCollector* collector, | |
| 7708 MemRegion span, | |
| 7709 ReferenceProcessor* rp, | |
| 7710 CMSBitMap* bit_map, | |
| 7711 CMSBitMap* mod_union_table, | |
| 7712 CMSMarkStack* mark_stack, | |
| 7713 bool concurrent_precleaning): | |
|
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7714 CMSOopClosure(rp), |
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7715 _collector(collector), |
| 0 | 7716 _span(span), |
| 7717 _bit_map(bit_map), | |
| 7718 _mod_union_table(mod_union_table), | |
| 7719 _mark_stack(mark_stack), | |
| 935 | 7720 _concurrent_precleaning(concurrent_precleaning) |
| 0 | 7721 { |
| 7722 assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL"); | |
| 7723 } | |
| 7724 | |
| 7725 // Grey object rescan during pre-cleaning and second checkpoint phases -- | |
| 7726 // the non-parallel version (the parallel version appears further below.) | |
|
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7727 void PushAndMarkClosure::do_oop(oop obj) { |
|
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7728 // Ignore mark word verification. If during concurrent precleaning, |
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7729 // the object monitor may be locked. If during the checkpoint |
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7730 // phases, the object may already have been reached by a different |
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7731 // path and may be at the end of the global overflow list (so |
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7732 // the mark word may be NULL). |
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7733 assert(obj->is_oop_or_null(true /* ignore mark word */), |
| 0 | 7734 "expected an oop or NULL"); |
|
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7735 HeapWord* addr = (HeapWord*)obj; |
| 0 | 7736 // Check if oop points into the CMS generation |
| 7737 // and is not marked | |
| 7738 if (_span.contains(addr) && !_bit_map->isMarked(addr)) { | |
| 7739 // a white object ... | |
| 7740 _bit_map->mark(addr); // ... now grey | |
| 7741 // push on the marking stack (grey set) | |
| 7742 bool simulate_overflow = false; | |
| 7743 NOT_PRODUCT( | |
| 7744 if (CMSMarkStackOverflowALot && | |
| 7745 _collector->simulate_overflow()) { | |
| 7746 // simulate a stack overflow | |
| 7747 simulate_overflow = true; | |
| 7748 } | |
| 7749 ) | |
|
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7750 if (simulate_overflow || !_mark_stack->push(obj)) { |
| 0 | 7751 if (_concurrent_precleaning) { |
|
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7752 // During precleaning we can just dirty the appropriate card(s) |
| 0 | 7753 // in the mod union table, thus ensuring that the object remains |
|
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7754 // in the grey set and continue. In the case of object arrays |
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7755 // we need to dirty all of the cards that the object spans, |
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7756 // since the rescan of object arrays will be limited to the |
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7757 // dirty cards. |
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7758 // Note that no one can be intefering with us in this action |
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7759 // of dirtying the mod union table, so no locking or atomics |
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7760 // are required. |
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7761 if (obj->is_objArray()) { |
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7762 size_t sz = obj->size(); |
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7763 HeapWord* end_card_addr = (HeapWord*)round_to( |
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7764 (intptr_t)(addr+sz), CardTableModRefBS::card_size); |
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7765 MemRegion redirty_range = MemRegion(addr, end_card_addr); |
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7766 assert(!redirty_range.is_empty(), "Arithmetical tautology"); |
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7767 _mod_union_table->mark_range(redirty_range); |
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7768 } else { |
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7769 _mod_union_table->mark(addr); |
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7770 } |
| 0 | 7771 _collector->_ser_pmc_preclean_ovflw++; |
| 7772 } else { | |
| 7773 // During the remark phase, we need to remember this oop | |
| 7774 // in the overflow list. | |
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7775 _collector->push_on_overflow_list(obj); |
| 0 | 7776 _collector->_ser_pmc_remark_ovflw++; |
| 7777 } | |
| 7778 } | |
| 7779 } | |
| 7780 } | |
| 7781 | |
| 7782 Par_PushAndMarkClosure::Par_PushAndMarkClosure(CMSCollector* collector, | |
| 7783 MemRegion span, | |
| 7784 ReferenceProcessor* rp, | |
| 7785 CMSBitMap* bit_map, | |
|
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7786 OopTaskQueue* work_queue): |
|
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|
7787 CMSOopClosure(rp), |
|
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|
7788 _collector(collector), |
| 0 | 7789 _span(span), |
| 7790 _bit_map(bit_map), | |
| 935 | 7791 _work_queue(work_queue) |
| 0 | 7792 { |
| 7793 assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL"); | |
| 7794 } | |
| 7795 | |
|
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|
7796 void PushAndMarkClosure::do_oop(oop* p) { PushAndMarkClosure::do_oop_work(p); } |
|
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7797 void PushAndMarkClosure::do_oop(narrowOop* p) { PushAndMarkClosure::do_oop_work(p); } |
|
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7798 |
| 0 | 7799 // Grey object rescan during second checkpoint phase -- |
| 7800 // the parallel version. | |
|
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|
7801 void Par_PushAndMarkClosure::do_oop(oop obj) { |
| 0 | 7802 // In the assert below, we ignore the mark word because |
| 7803 // this oop may point to an already visited object that is | |
| 7804 // on the overflow stack (in which case the mark word has | |
| 7805 // been hijacked for chaining into the overflow stack -- | |
| 7806 // if this is the last object in the overflow stack then | |
| 7807 // its mark word will be NULL). Because this object may | |
| 7808 // have been subsequently popped off the global overflow | |
| 7809 // stack, and the mark word possibly restored to the prototypical | |
| 7810 // value, by the time we get to examined this failing assert in | |
| 7811 // the debugger, is_oop_or_null(false) may subsequently start | |
| 7812 // to hold. | |
|
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|
7813 assert(obj->is_oop_or_null(true), |
| 0 | 7814 "expected an oop or NULL"); |
|
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|
7815 HeapWord* addr = (HeapWord*)obj; |
| 0 | 7816 // Check if oop points into the CMS generation |
| 7817 // and is not marked | |
| 7818 if (_span.contains(addr) && !_bit_map->isMarked(addr)) { | |
| 7819 // a white object ... | |
| 7820 // If we manage to "claim" the object, by being the | |
| 7821 // first thread to mark it, then we push it on our | |
| 7822 // marking stack | |
| 7823 if (_bit_map->par_mark(addr)) { // ... now grey | |
| 7824 // push on work queue (grey set) | |
| 7825 bool simulate_overflow = false; | |
| 7826 NOT_PRODUCT( | |
| 7827 if (CMSMarkStackOverflowALot && | |
| 7828 _collector->par_simulate_overflow()) { | |
| 7829 // simulate a stack overflow | |
| 7830 simulate_overflow = true; | |
| 7831 } | |
| 7832 ) | |
|
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|
7833 if (simulate_overflow || !_work_queue->push(obj)) { |
|
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|
7834 _collector->par_push_on_overflow_list(obj); |
| 0 | 7835 _collector->_par_pmc_remark_ovflw++; // imprecise OK: no need to CAS |
| 7836 } | |
| 7837 } // Else, some other thread got there first | |
| 7838 } | |
| 7839 } | |
| 7840 | |
|
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|
7841 void Par_PushAndMarkClosure::do_oop(oop* p) { Par_PushAndMarkClosure::do_oop_work(p); } |
|
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|
7842 void Par_PushAndMarkClosure::do_oop(narrowOop* p) { Par_PushAndMarkClosure::do_oop_work(p); } |
|
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|
7843 |
| 0 | 7844 void CMSPrecleanRefsYieldClosure::do_yield_work() { |
| 7845 Mutex* bml = _collector->bitMapLock(); | |
| 7846 assert_lock_strong(bml); | |
| 7847 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 7848 "CMS thread should hold CMS token"); | |
| 7849 | |
| 7850 bml->unlock(); | |
| 7851 ConcurrentMarkSweepThread::desynchronize(true); | |
| 7852 | |
| 7853 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7854 | |
| 7855 _collector->stopTimer(); | |
| 7856 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 7857 if (PrintCMSStatistics != 0) { | |
| 7858 _collector->incrementYields(); | |
| 7859 } | |
| 7860 _collector->icms_wait(); | |
| 7861 | |
| 7862 // See the comment in coordinator_yield() | |
| 7863 for (unsigned i = 0; i < CMSYieldSleepCount && | |
| 7864 ConcurrentMarkSweepThread::should_yield() && | |
| 7865 !CMSCollector::foregroundGCIsActive(); ++i) { | |
| 7866 os::sleep(Thread::current(), 1, false); | |
| 7867 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7868 } | |
| 7869 | |
| 7870 ConcurrentMarkSweepThread::synchronize(true); | |
| 7871 bml->lock(); | |
| 7872 | |
| 7873 _collector->startTimer(); | |
| 7874 } | |
| 7875 | |
| 7876 bool CMSPrecleanRefsYieldClosure::should_return() { | |
| 7877 if (ConcurrentMarkSweepThread::should_yield()) { | |
| 7878 do_yield_work(); | |
| 7879 } | |
| 7880 return _collector->foregroundGCIsActive(); | |
| 7881 } | |
| 7882 | |
| 7883 void MarkFromDirtyCardsClosure::do_MemRegion(MemRegion mr) { | |
| 7884 assert(((size_t)mr.start())%CardTableModRefBS::card_size_in_words == 0, | |
| 7885 "mr should be aligned to start at a card boundary"); | |
| 7886 // We'd like to assert: | |
| 7887 // assert(mr.word_size()%CardTableModRefBS::card_size_in_words == 0, | |
| 7888 // "mr should be a range of cards"); | |
| 7889 // However, that would be too strong in one case -- the last | |
| 7890 // partition ends at _unallocated_block which, in general, can be | |
| 7891 // an arbitrary boundary, not necessarily card aligned. | |
| 7892 if (PrintCMSStatistics != 0) { | |
| 7893 _num_dirty_cards += | |
| 7894 mr.word_size()/CardTableModRefBS::card_size_in_words; | |
| 7895 } | |
| 7896 _space->object_iterate_mem(mr, &_scan_cl); | |
| 7897 } | |
| 7898 | |
| 7899 SweepClosure::SweepClosure(CMSCollector* collector, | |
| 7900 ConcurrentMarkSweepGeneration* g, | |
| 7901 CMSBitMap* bitMap, bool should_yield) : | |
| 7902 _collector(collector), | |
| 7903 _g(g), | |
| 7904 _sp(g->cmsSpace()), | |
| 7905 _limit(_sp->sweep_limit()), | |
| 7906 _freelistLock(_sp->freelistLock()), | |
| 7907 _bitMap(bitMap), | |
| 7908 _yield(should_yield), | |
| 7909 _inFreeRange(false), // No free range at beginning of sweep | |
| 7910 _freeRangeInFreeLists(false), // No free range at beginning of sweep | |
| 7911 _lastFreeRangeCoalesced(false), | |
| 7912 _freeFinger(g->used_region().start()) | |
| 7913 { | |
| 7914 NOT_PRODUCT( | |
| 7915 _numObjectsFreed = 0; | |
| 7916 _numWordsFreed = 0; | |
| 7917 _numObjectsLive = 0; | |
| 7918 _numWordsLive = 0; | |
| 7919 _numObjectsAlreadyFree = 0; | |
| 7920 _numWordsAlreadyFree = 0; | |
| 7921 _last_fc = NULL; | |
| 7922 | |
| 7923 _sp->initializeIndexedFreeListArrayReturnedBytes(); | |
|
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|
7924 _sp->dictionary()->initialize_dict_returned_bytes(); |
| 0 | 7925 ) |
| 7926 assert(_limit >= _sp->bottom() && _limit <= _sp->end(), | |
| 7927 "sweep _limit out of bounds"); | |
| 7928 if (CMSTraceSweeper) { | |
|
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|
7929 gclog_or_tty->print_cr("\n====================\nStarting new sweep with limit " PTR_FORMAT, |
|
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|
7930 _limit); |
|
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|
7931 } |
|
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|
7932 } |
|
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|
7933 |
|
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|
7934 void SweepClosure::print_on(outputStream* st) const { |
|
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|
7935 tty->print_cr("_sp = [" PTR_FORMAT "," PTR_FORMAT ")", |
|
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|
7936 _sp->bottom(), _sp->end()); |
|
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|
7937 tty->print_cr("_limit = " PTR_FORMAT, _limit); |
|
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|
7938 tty->print_cr("_freeFinger = " PTR_FORMAT, _freeFinger); |
|
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|
7939 NOT_PRODUCT(tty->print_cr("_last_fc = " PTR_FORMAT, _last_fc);) |
|
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|
7940 tty->print_cr("_inFreeRange = %d, _freeRangeInFreeLists = %d, _lastFreeRangeCoalesced = %d", |
|
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|
7941 _inFreeRange, _freeRangeInFreeLists, _lastFreeRangeCoalesced); |
|
537a4053b0f9
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|
7942 } |
|
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|
7943 |
|
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|
7944 #ifndef PRODUCT |
|
537a4053b0f9
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|
7945 // Assertion checking only: no useful work in product mode -- |
|
537a4053b0f9
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|
7946 // however, if any of the flags below become product flags, |
|
537a4053b0f9
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|
7947 // you may need to review this code to see if it needs to be |
|
537a4053b0f9
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|
7948 // enabled in product mode. |
| 0 | 7949 SweepClosure::~SweepClosure() { |
| 7950 assert_lock_strong(_freelistLock); | |
|
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|
7951 assert(_limit >= _sp->bottom() && _limit <= _sp->end(), |
|
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|
7952 "sweep _limit out of bounds"); |
| 0 | 7953 if (inFreeRange()) { |
|
3746
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|
7954 warning("inFreeRange() should have been reset; dumping state of SweepClosure"); |
|
537a4053b0f9
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|
7955 print(); |
|
537a4053b0f9
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|
7956 ShouldNotReachHere(); |
|
537a4053b0f9
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|
7957 } |
|
537a4053b0f9
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|
7958 if (Verbose && PrintGC) { |
|
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|
7959 gclog_or_tty->print("Collected "SIZE_FORMAT" objects, " SIZE_FORMAT " bytes", |
|
537a4053b0f9
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|
7960 _numObjectsFreed, _numWordsFreed*sizeof(HeapWord)); |
|
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|
7961 gclog_or_tty->print_cr("\nLive "SIZE_FORMAT" objects, " |
|
537a4053b0f9
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|
7962 SIZE_FORMAT" bytes " |
|
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|
7963 "Already free "SIZE_FORMAT" objects, "SIZE_FORMAT" bytes", |
|
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|
7964 _numObjectsLive, _numWordsLive*sizeof(HeapWord), |
|
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|
7965 _numObjectsAlreadyFree, _numWordsAlreadyFree*sizeof(HeapWord)); |
|
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|
7966 size_t totalBytes = (_numWordsFreed + _numWordsLive + _numWordsAlreadyFree) |
|
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|
7967 * sizeof(HeapWord); |
|
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|
7968 gclog_or_tty->print_cr("Total sweep: "SIZE_FORMAT" bytes", totalBytes); |
|
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|
7969 |
|
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|
7970 if (PrintCMSStatistics && CMSVerifyReturnedBytes) { |
|
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|
7971 size_t indexListReturnedBytes = _sp->sumIndexedFreeListArrayReturnedBytes(); |
|
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7972 size_t dict_returned_bytes = _sp->dictionary()->sum_dict_returned_bytes(); |
|
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|
7973 size_t returned_bytes = indexListReturnedBytes + dict_returned_bytes; |
|
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|
7974 gclog_or_tty->print("Returned "SIZE_FORMAT" bytes", returned_bytes); |
|
3746
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|
7975 gclog_or_tty->print(" Indexed List Returned "SIZE_FORMAT" bytes", |
|
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|
7976 indexListReturnedBytes); |
|
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|
7977 gclog_or_tty->print_cr(" Dictionary Returned "SIZE_FORMAT" bytes", |
|
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|
7978 dict_returned_bytes); |
|
3746
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|
7979 } |
|
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|
7980 } |
| 0 | 7981 if (CMSTraceSweeper) { |
|
3746
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|
7982 gclog_or_tty->print_cr("end of sweep with _limit = " PTR_FORMAT "\n================", |
|
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|
7983 _limit); |
|
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|
7984 } |
|
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|
7985 } |
|
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|
7986 #endif // PRODUCT |
| 0 | 7987 |
| 7988 void SweepClosure::initialize_free_range(HeapWord* freeFinger, | |
| 7989 bool freeRangeInFreeLists) { | |
| 7990 if (CMSTraceSweeper) { | |
|
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|
7991 gclog_or_tty->print("---- Start free range at 0x%x with free block (%d)\n", |
|
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|
7992 freeFinger, freeRangeInFreeLists); |
| 0 | 7993 } |
| 7994 assert(!inFreeRange(), "Trampling existing free range"); | |
| 7995 set_inFreeRange(true); | |
| 7996 set_lastFreeRangeCoalesced(false); | |
| 7997 | |
| 7998 set_freeFinger(freeFinger); | |
| 7999 set_freeRangeInFreeLists(freeRangeInFreeLists); | |
| 8000 if (CMSTestInFreeList) { | |
| 8001 if (freeRangeInFreeLists) { | |
| 8002 FreeChunk* fc = (FreeChunk*) freeFinger; | |
|
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|
8003 assert(fc->is_free(), "A chunk on the free list should be free."); |
| 0 | 8004 assert(fc->size() > 0, "Free range should have a size"); |
|
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|
8005 assert(_sp->verify_chunk_in_free_list(fc), "Chunk is not in free lists"); |
| 0 | 8006 } |
| 8007 } | |
| 8008 } | |
| 8009 | |
| 8010 // Note that the sweeper runs concurrently with mutators. Thus, | |
| 8011 // it is possible for direct allocation in this generation to happen | |
| 8012 // in the middle of the sweep. Note that the sweeper also coalesces | |
| 8013 // contiguous free blocks. Thus, unless the sweeper and the allocator | |
| 8014 // synchronize appropriately freshly allocated blocks may get swept up. | |
| 8015 // This is accomplished by the sweeper locking the free lists while | |
| 8016 // it is sweeping. Thus blocks that are determined to be free are | |
| 8017 // indeed free. There is however one additional complication: | |
| 8018 // blocks that have been allocated since the final checkpoint and | |
| 8019 // mark, will not have been marked and so would be treated as | |
| 8020 // unreachable and swept up. To prevent this, the allocator marks | |
| 8021 // the bit map when allocating during the sweep phase. This leads, | |
| 8022 // however, to a further complication -- objects may have been allocated | |
| 8023 // but not yet initialized -- in the sense that the header isn't yet | |
| 8024 // installed. The sweeper can not then determine the size of the block | |
| 8025 // in order to skip over it. To deal with this case, we use a technique | |
| 8026 // (due to Printezis) to encode such uninitialized block sizes in the | |
| 8027 // bit map. Since the bit map uses a bit per every HeapWord, but the | |
| 8028 // CMS generation has a minimum object size of 3 HeapWords, it follows | |
| 8029 // that "normal marks" won't be adjacent in the bit map (there will | |
| 8030 // always be at least two 0 bits between successive 1 bits). We make use | |
| 8031 // of these "unused" bits to represent uninitialized blocks -- the bit | |
| 8032 // corresponding to the start of the uninitialized object and the next | |
| 8033 // bit are both set. Finally, a 1 bit marks the end of the object that | |
| 8034 // started with the two consecutive 1 bits to indicate its potentially | |
| 8035 // uninitialized state. | |
| 8036 | |
| 8037 size_t SweepClosure::do_blk_careful(HeapWord* addr) { | |
| 8038 FreeChunk* fc = (FreeChunk*)addr; | |
| 8039 size_t res; | |
| 8040 | |
|
1720
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6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
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1716
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|
8041 // Check if we are done sweeping. Below we check "addr >= _limit" rather |
|
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
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|
8042 // than "addr == _limit" because although _limit was a block boundary when |
|
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
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|
8043 // 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
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|
8044 // 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
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|
8045 // with a newly expanded chunk (this happens when _limit was set to the |
|
3746
537a4053b0f9
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|
8046 // previous _end of the space), so we may have stepped past _limit: |
|
537a4053b0f9
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|
8047 // see the following Zeno-like trail of CRs 6977970, 7008136, 7042740. |
|
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|
8048 if (addr >= _limit) { // we have swept up to or past the limit: finish up |
| 0 | 8049 assert(_limit >= _sp->bottom() && _limit <= _sp->end(), |
| 8050 "sweep _limit out of bounds"); | |
|
1720
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6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
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|
8051 assert(addr < _sp->end(), "addr out of bounds"); |
|
3746
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|
8052 // Flush any free range we might be holding as a single |
|
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|
8053 // coalesced chunk to the appropriate free list. |
|
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7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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|
8054 if (inFreeRange()) { |
|
3746
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|
8055 assert(freeFinger() >= _sp->bottom() && freeFinger() < _limit, |
|
537a4053b0f9
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|
8056 err_msg("freeFinger() " PTR_FORMAT" is out-of-bounds", freeFinger())); |
|
2132
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|
8057 flush_cur_free_chunk(freeFinger(), |
|
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7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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|
8058 pointer_delta(addr, freeFinger())); |
|
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|
8059 if (CMSTraceSweeper) { |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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diff
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|
8060 gclog_or_tty->print("Sweep: last chunk: "); |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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diff
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|
8061 gclog_or_tty->print("put_free_blk 0x%x ("SIZE_FORMAT") " |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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|
8062 "[coalesced:"SIZE_FORMAT"]\n", |
|
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7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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diff
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|
8063 freeFinger(), pointer_delta(addr, freeFinger()), |
|
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7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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diff
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|
8064 lastFreeRangeCoalesced()); |
|
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7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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diff
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|
8065 } |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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|
8066 } |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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diff
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|
8067 |
|
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7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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|
8068 // help the iterator loop finish |
|
1720
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|
8069 return pointer_delta(_sp->end(), addr); |
|
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
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|
8070 } |
|
2132
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|
8071 |
|
1720
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|
8072 assert(addr < _limit, "sweep invariant"); |
| 0 | 8073 // check if we should yield |
| 8074 do_yield_check(addr); | |
|
6028
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|
8075 if (fc->is_free()) { |
| 0 | 8076 // Chunk that is already free |
| 8077 res = fc->size(); | |
|
2132
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|
8078 do_already_free_chunk(fc); |
| 0 | 8079 debug_only(_sp->verifyFreeLists()); |
|
3746
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|
8080 // If we flush the chunk at hand in lookahead_and_flush() |
|
537a4053b0f9
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|
8081 // and it's coalesced with a preceding chunk, then the |
|
537a4053b0f9
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changeset
|
8082 // process of "mangling" the payload of the coalesced block |
|
537a4053b0f9
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|
8083 // will cause erasure of the size information from the |
|
537a4053b0f9
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|
8084 // (erstwhile) header of all the coalesced blocks but the |
|
537a4053b0f9
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|
8085 // first, so the first disjunct in the assert will not hold |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8086 // in that specific case (in which case the second disjunct |
|
537a4053b0f9
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|
8087 // will hold). |
|
537a4053b0f9
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3356
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|
8088 assert(res == fc->size() || ((HeapWord*)fc) + res >= _limit, |
|
537a4053b0f9
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|
8089 "Otherwise the size info doesn't change at this step"); |
| 0 | 8090 NOT_PRODUCT( |
| 8091 _numObjectsAlreadyFree++; | |
| 8092 _numWordsAlreadyFree += res; | |
| 8093 ) | |
| 8094 NOT_PRODUCT(_last_fc = fc;) | |
| 8095 } else if (!_bitMap->isMarked(addr)) { | |
| 8096 // Chunk is fresh garbage | |
|
2132
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1994
diff
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|
8097 res = do_garbage_chunk(fc); |
| 0 | 8098 debug_only(_sp->verifyFreeLists()); |
| 8099 NOT_PRODUCT( | |
| 8100 _numObjectsFreed++; | |
| 8101 _numWordsFreed += res; | |
| 8102 ) | |
| 8103 } else { | |
| 8104 // Chunk that is alive. | |
|
2132
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1994
diff
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|
8105 res = do_live_chunk(fc); |
| 0 | 8106 debug_only(_sp->verifyFreeLists()); |
| 8107 NOT_PRODUCT( | |
| 8108 _numObjectsLive++; | |
| 8109 _numWordsLive += res; | |
| 8110 ) | |
| 8111 } | |
| 8112 return res; | |
| 8113 } | |
| 8114 | |
| 8115 // For the smart allocation, record following | |
| 8116 // split deaths - a free chunk is removed from its free list because | |
| 8117 // it is being split into two or more chunks. | |
| 8118 // split birth - a free chunk is being added to its free list because | |
| 8119 // a larger free chunk has been split and resulted in this free chunk. | |
| 8120 // coal death - a free chunk is being removed from its free list because | |
| 8121 // it is being coalesced into a large free chunk. | |
| 8122 // coal birth - a free chunk is being added to its free list because | |
| 8123 // it was created when two or more free chunks where coalesced into | |
| 8124 // this free chunk. | |
| 8125 // | |
| 8126 // These statistics are used to determine the desired number of free | |
| 8127 // chunks of a given size. The desired number is chosen to be relative | |
| 8128 // to the end of a CMS sweep. The desired number at the end of a sweep | |
| 8129 // is the | |
| 8130 // count-at-end-of-previous-sweep (an amount that was enough) | |
| 8131 // - count-at-beginning-of-current-sweep (the excess) | |
| 8132 // + split-births (gains in this size during interval) | |
| 8133 // - split-deaths (demands on this size during interval) | |
| 8134 // where the interval is from the end of one sweep to the end of the | |
| 8135 // next. | |
| 8136 // | |
| 8137 // When sweeping the sweeper maintains an accumulated chunk which is | |
| 8138 // the chunk that is made up of chunks that have been coalesced. That | |
| 8139 // will be termed the left-hand chunk. A new chunk of garbage that | |
| 8140 // is being considered for coalescing will be referred to as the | |
| 8141 // right-hand chunk. | |
| 8142 // | |
| 8143 // When making a decision on whether to coalesce a right-hand chunk with | |
| 8144 // the current left-hand chunk, the current count vs. the desired count | |
| 8145 // of the left-hand chunk is considered. Also if the right-hand chunk | |
| 8146 // is near the large chunk at the end of the heap (see | |
| 8147 // ConcurrentMarkSweepGeneration::isNearLargestChunk()), then the | |
| 8148 // left-hand chunk is coalesced. | |
| 8149 // | |
| 8150 // When making a decision about whether to split a chunk, the desired count | |
| 8151 // vs. the current count of the candidate to be split is also considered. | |
| 8152 // If the candidate is underpopulated (currently fewer chunks than desired) | |
| 8153 // a chunk of an overpopulated (currently more chunks than desired) size may | |
| 8154 // be chosen. The "hint" associated with a free list, if non-null, points | |
| 8155 // to a free list which may be overpopulated. | |
| 8156 // | |
| 8157 | |
|
2132
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7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
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|
8158 void SweepClosure::do_already_free_chunk(FreeChunk* fc) { |
|
3746
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3356
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|
8159 const size_t size = fc->size(); |
| 0 | 8160 // Chunks that cannot be coalesced are not in the |
| 8161 // free lists. | |
| 8162 if (CMSTestInFreeList && !fc->cantCoalesce()) { | |
|
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6026
diff
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|
8163 assert(_sp->verify_chunk_in_free_list(fc), |
| 0 | 8164 "free chunk should be in free lists"); |
| 8165 } | |
| 8166 // a chunk that is already free, should not have been | |
| 8167 // marked in the bit map | |
|
3746
537a4053b0f9
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3356
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|
8168 HeapWord* const addr = (HeapWord*) fc; |
| 0 | 8169 assert(!_bitMap->isMarked(addr), "free chunk should be unmarked"); |
| 8170 // Verify that the bit map has no bits marked between | |
| 8171 // addr and purported end of this block. | |
| 8172 _bitMap->verifyNoOneBitsInRange(addr + 1, addr + size); | |
| 8173 | |
|
2132
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diff
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|
8174 // Some chunks cannot be coalesced under any circumstances. |
| 0 | 8175 // See the definition of cantCoalesce(). |
| 8176 if (!fc->cantCoalesce()) { | |
| 8177 // This chunk can potentially be coalesced. | |
| 8178 if (_sp->adaptive_freelists()) { | |
| 8179 // All the work is done in | |
|
2132
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7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
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|
8180 do_post_free_or_garbage_chunk(fc, size); |
| 0 | 8181 } else { // Not adaptive free lists |
| 8182 // this is a free chunk that can potentially be coalesced by the sweeper; | |
| 8183 if (!inFreeRange()) { | |
| 8184 // if the next chunk is a free block that can't be coalesced | |
| 8185 // it doesn't make sense to remove this chunk from the free lists | |
| 8186 FreeChunk* nextChunk = (FreeChunk*)(addr + size); | |
|
2136
c91cc404ca46
7011940: iCMS: SIGSEGV in SweepClosure::do_already_free_chunk(FreeChunk*)+0x360
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2132
diff
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|
8187 assert((HeapWord*)nextChunk <= _sp->end(), "Chunk size out of bounds?"); |
|
c91cc404ca46
7011940: iCMS: SIGSEGV in SweepClosure::do_already_free_chunk(FreeChunk*)+0x360
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2132
diff
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|
8188 if ((HeapWord*)nextChunk < _sp->end() && // There is another free chunk to the right ... |
|
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|
8189 nextChunk->is_free() && // ... which is free... |
|
2136
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2132
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|
8190 nextChunk->cantCoalesce()) { // ... but can't be coalesced |
| 0 | 8191 // nothing to do |
| 8192 } else { | |
| 8193 // Potentially the start of a new free range: | |
| 8194 // Don't eagerly remove it from the free lists. | |
| 8195 // No need to remove it if it will just be put | |
| 8196 // back again. (Also from a pragmatic point of view | |
| 8197 // if it is a free block in a region that is beyond | |
| 8198 // any allocated blocks, an assertion will fail) | |
| 8199 // Remember the start of a free run. | |
| 8200 initialize_free_range(addr, true); | |
| 8201 // end - can coalesce with next chunk | |
| 8202 } | |
| 8203 } else { | |
| 8204 // the midst of a free range, we are coalescing | |
|
3746
537a4053b0f9
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3356
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|
8205 print_free_block_coalesced(fc); |
| 0 | 8206 if (CMSTraceSweeper) { |
| 8207 gclog_or_tty->print(" -- pick up free block 0x%x (%d)\n", fc, size); | |
| 8208 } | |
| 8209 // remove it from the free lists | |
| 8210 _sp->removeFreeChunkFromFreeLists(fc); | |
| 8211 set_lastFreeRangeCoalesced(true); | |
| 8212 // If the chunk is being coalesced and the current free range is | |
| 8213 // in the free lists, remove the current free range so that it | |
| 8214 // will be returned to the free lists in its entirety - all | |
| 8215 // the coalesced pieces included. | |
| 8216 if (freeRangeInFreeLists()) { | |
| 8217 FreeChunk* ffc = (FreeChunk*) freeFinger(); | |
| 8218 assert(ffc->size() == pointer_delta(addr, freeFinger()), | |
| 8219 "Size of free range is inconsistent with chunk size."); | |
| 8220 if (CMSTestInFreeList) { | |
|
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6026
diff
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|
8221 assert(_sp->verify_chunk_in_free_list(ffc), |
| 0 | 8222 "free range is not in free lists"); |
| 8223 } | |
| 8224 _sp->removeFreeChunkFromFreeLists(ffc); | |
| 8225 set_freeRangeInFreeLists(false); | |
| 8226 } | |
| 8227 } | |
| 8228 } | |
|
3746
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3356
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|
8229 // Note that if the chunk is not coalescable (the else arm |
|
537a4053b0f9
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3356
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|
8230 // below), we unconditionally flush, without needing to do |
|
537a4053b0f9
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|
8231 // a "lookahead," as we do below. |
|
537a4053b0f9
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ysr
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3356
diff
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|
8232 if (inFreeRange()) lookahead_and_flush(fc, size); |
| 0 | 8233 } else { |
| 8234 // Code path common to both original and adaptive free lists. | |
| 8235 | |
| 8236 // cant coalesce with previous block; this should be treated | |
| 8237 // as the end of a free run if any | |
| 8238 if (inFreeRange()) { | |
| 8239 // we kicked some butt; time to pick up the garbage | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
changeset
|
8240 assert(freeFinger() < addr, "freeFinger points too high"); |
|
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7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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|
8241 flush_cur_free_chunk(freeFinger(), pointer_delta(addr, freeFinger())); |
| 0 | 8242 } |
| 8243 // else, nothing to do, just continue | |
| 8244 } | |
| 8245 } | |
| 8246 | |
|
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diff
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|
8247 size_t SweepClosure::do_garbage_chunk(FreeChunk* fc) { |
| 0 | 8248 // This is a chunk of garbage. It is not in any free list. |
| 8249 // Add it to a free list or let it possibly be coalesced into | |
| 8250 // a larger chunk. | |
|
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|
8251 HeapWord* const addr = (HeapWord*) fc; |
|
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changeset
|
8252 const size_t size = CompactibleFreeListSpace::adjustObjectSize(oop(addr)->size()); |
| 0 | 8253 |
| 8254 if (_sp->adaptive_freelists()) { | |
| 8255 // Verify that the bit map has no bits marked between | |
| 8256 // addr and purported end of just dead object. | |
| 8257 _bitMap->verifyNoOneBitsInRange(addr + 1, addr + size); | |
| 8258 | |
|
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|
8259 do_post_free_or_garbage_chunk(fc, size); |
| 0 | 8260 } else { |
| 8261 if (!inFreeRange()) { | |
| 8262 // start of a new free range | |
| 8263 assert(size > 0, "A free range should have a size"); | |
| 8264 initialize_free_range(addr, false); | |
| 8265 } else { | |
| 8266 // this will be swept up when we hit the end of the | |
| 8267 // free range | |
| 8268 if (CMSTraceSweeper) { | |
| 8269 gclog_or_tty->print(" -- pick up garbage 0x%x (%d) \n", fc, size); | |
| 8270 } | |
| 8271 // If the chunk is being coalesced and the current free range is | |
| 8272 // in the free lists, remove the current free range so that it | |
| 8273 // will be returned to the free lists in its entirety - all | |
| 8274 // the coalesced pieces included. | |
| 8275 if (freeRangeInFreeLists()) { | |
| 8276 FreeChunk* ffc = (FreeChunk*)freeFinger(); | |
| 8277 assert(ffc->size() == pointer_delta(addr, freeFinger()), | |
| 8278 "Size of free range is inconsistent with chunk size."); | |
| 8279 if (CMSTestInFreeList) { | |
|
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|
8280 assert(_sp->verify_chunk_in_free_list(ffc), |
| 0 | 8281 "free range is not in free lists"); |
| 8282 } | |
| 8283 _sp->removeFreeChunkFromFreeLists(ffc); | |
| 8284 set_freeRangeInFreeLists(false); | |
| 8285 } | |
| 8286 set_lastFreeRangeCoalesced(true); | |
| 8287 } | |
| 8288 // this will be swept up when we hit the end of the free range | |
| 8289 | |
| 8290 // Verify that the bit map has no bits marked between | |
| 8291 // addr and purported end of just dead object. | |
| 8292 _bitMap->verifyNoOneBitsInRange(addr + 1, addr + size); | |
| 8293 } | |
|
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changeset
|
8294 assert(_limit >= addr + size, |
|
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|
8295 "A freshly garbage chunk can't possibly straddle over _limit"); |
|
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changeset
|
8296 if (inFreeRange()) lookahead_and_flush(fc, size); |
| 0 | 8297 return size; |
| 8298 } | |
| 8299 | |
|
2132
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changeset
|
8300 size_t SweepClosure::do_live_chunk(FreeChunk* fc) { |
| 0 | 8301 HeapWord* addr = (HeapWord*) fc; |
| 8302 // The sweeper has just found a live object. Return any accumulated | |
| 8303 // left hand chunk to the free lists. | |
| 8304 if (inFreeRange()) { | |
|
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diff
changeset
|
8305 assert(freeFinger() < addr, "freeFinger points too high"); |
|
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7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
changeset
|
8306 flush_cur_free_chunk(freeFinger(), pointer_delta(addr, freeFinger())); |
|
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7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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changeset
|
8307 } |
|
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7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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diff
changeset
|
8308 |
|
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diff
changeset
|
8309 // This object is live: we'd normally expect this to be |
| 0 | 8310 // an oop, and like to assert the following: |
| 8311 // assert(oop(addr)->is_oop(), "live block should be an oop"); | |
| 8312 // However, as we commented above, this may be an object whose | |
| 8313 // header hasn't yet been initialized. | |
| 8314 size_t size; | |
| 8315 assert(_bitMap->isMarked(addr), "Tautology for this control point"); | |
| 8316 if (_bitMap->isMarked(addr + 1)) { | |
| 8317 // Determine the size from the bit map, rather than trying to | |
| 8318 // compute it from the object header. | |
| 8319 HeapWord* nextOneAddr = _bitMap->getNextMarkedWordAddress(addr + 2); | |
| 8320 size = pointer_delta(nextOneAddr + 1, addr); | |
| 8321 assert(size == CompactibleFreeListSpace::adjustObjectSize(size), | |
| 8322 "alignment problem"); | |
| 8323 | |
| 9152 | 8324 #ifdef ASSERT |
|
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coleenp
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6197
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changeset
|
8325 if (oop(addr)->klass_or_null() != NULL) { |
| 0 | 8326 // Ignore mark word because we are running concurrent with mutators |
| 8327 assert(oop(addr)->is_oop(true), "live block should be an oop"); | |
| 8328 assert(size == | |
| 8329 CompactibleFreeListSpace::adjustObjectSize(oop(addr)->size()), | |
| 8330 "P-mark and computed size do not agree"); | |
| 8331 } | |
|
2132
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diff
changeset
|
8332 #endif |
| 0 | 8333 |
| 8334 } else { | |
| 8335 // This should be an initialized object that's alive. | |
|
6725
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|
8336 assert(oop(addr)->klass_or_null() != NULL, |
| 0 | 8337 "Should be an initialized object"); |
| 8338 // Ignore mark word because we are running concurrent with mutators | |
| 8339 assert(oop(addr)->is_oop(true), "live block should be an oop"); | |
| 8340 // Verify that the bit map has no bits marked between | |
| 8341 // addr and purported end of this block. | |
| 8342 size = CompactibleFreeListSpace::adjustObjectSize(oop(addr)->size()); | |
| 8343 assert(size >= 3, "Necessary for Printezis marks to work"); | |
| 8344 assert(!_bitMap->isMarked(addr+1), "Tautology for this control point"); | |
| 8345 DEBUG_ONLY(_bitMap->verifyNoOneBitsInRange(addr+2, addr+size);) | |
| 8346 } | |
| 8347 return size; | |
| 8348 } | |
| 8349 | |
|
2132
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1994
diff
changeset
|
8350 void SweepClosure::do_post_free_or_garbage_chunk(FreeChunk* fc, |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
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|
8351 size_t chunkSize) { |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8352 // do_post_free_or_garbage_chunk() should only be called in the case |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
changeset
|
8353 // of the adaptive free list allocator. |
|
6028
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jmasa
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6026
diff
changeset
|
8354 const bool fcInFreeLists = fc->is_free(); |
| 0 | 8355 assert(_sp->adaptive_freelists(), "Should only be used in this case."); |
| 8356 assert((HeapWord*)fc <= _limit, "sweep invariant"); | |
| 8357 if (CMSTestInFreeList && fcInFreeLists) { | |
|
6028
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jmasa
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6026
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|
8358 assert(_sp->verify_chunk_in_free_list(fc), "free chunk is not in free lists"); |
|
2132
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1994
diff
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|
8359 } |
| 0 | 8360 |
| 8361 if (CMSTraceSweeper) { | |
| 8362 gclog_or_tty->print_cr(" -- pick up another chunk at 0x%x (%d)", fc, chunkSize); | |
| 8363 } | |
| 8364 | |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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3356
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changeset
|
8365 HeapWord* const fc_addr = (HeapWord*) fc; |
| 0 | 8366 |
| 8367 bool coalesce; | |
|
3746
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parents:
3356
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|
8368 const size_t left = pointer_delta(fc_addr, freeFinger()); |
|
537a4053b0f9
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parents:
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|
8369 const size_t right = chunkSize; |
| 0 | 8370 switch (FLSCoalescePolicy) { |
| 8371 // numeric value forms a coalition aggressiveness metric | |
| 8372 case 0: { // never coalesce | |
| 8373 coalesce = false; | |
| 8374 break; | |
| 8375 } | |
| 8376 case 1: { // coalesce if left & right chunks on overpopulated lists | |
| 8377 coalesce = _sp->coalOverPopulated(left) && | |
| 8378 _sp->coalOverPopulated(right); | |
| 8379 break; | |
| 8380 } | |
| 8381 case 2: { // coalesce if left chunk on overpopulated list (default) | |
| 8382 coalesce = _sp->coalOverPopulated(left); | |
| 8383 break; | |
| 8384 } | |
| 8385 case 3: { // coalesce if left OR right chunk on overpopulated list | |
| 8386 coalesce = _sp->coalOverPopulated(left) || | |
| 8387 _sp->coalOverPopulated(right); | |
| 8388 break; | |
| 8389 } | |
| 8390 case 4: { // always coalesce | |
| 8391 coalesce = true; | |
| 8392 break; | |
| 8393 } | |
| 8394 default: | |
| 8395 ShouldNotReachHere(); | |
| 8396 } | |
| 8397 | |
| 8398 // Should the current free range be coalesced? | |
| 8399 // If the chunk is in a free range and either we decided to coalesce above | |
| 8400 // or the chunk is near the large block at the end of the heap | |
| 8401 // (isNearLargestChunk() returns true), then coalesce this chunk. | |
|
3746
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3356
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|
8402 const bool doCoalesce = inFreeRange() |
|
537a4053b0f9
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ysr
parents:
3356
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changeset
|
8403 && (coalesce || _g->isNearLargestChunk(fc_addr)); |
| 0 | 8404 if (doCoalesce) { |
| 8405 // Coalesce the current free range on the left with the new | |
| 8406 // chunk on the right. If either is on a free list, | |
| 8407 // it must be removed from the list and stashed in the closure. | |
| 8408 if (freeRangeInFreeLists()) { | |
|
3746
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parents:
3356
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changeset
|
8409 FreeChunk* const ffc = (FreeChunk*)freeFinger(); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8410 assert(ffc->size() == pointer_delta(fc_addr, freeFinger()), |
| 0 | 8411 "Size of free range is inconsistent with chunk size."); |
| 8412 if (CMSTestInFreeList) { | |
|
6028
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7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
parents:
6026
diff
changeset
|
8413 assert(_sp->verify_chunk_in_free_list(ffc), |
| 0 | 8414 "Chunk is not in free lists"); |
| 8415 } | |
| 8416 _sp->coalDeath(ffc->size()); | |
| 8417 _sp->removeFreeChunkFromFreeLists(ffc); | |
| 8418 set_freeRangeInFreeLists(false); | |
| 8419 } | |
| 8420 if (fcInFreeLists) { | |
| 8421 _sp->coalDeath(chunkSize); | |
| 8422 assert(fc->size() == chunkSize, | |
| 8423 "The chunk has the wrong size or is not in the free lists"); | |
| 8424 _sp->removeFreeChunkFromFreeLists(fc); | |
| 8425 } | |
| 8426 set_lastFreeRangeCoalesced(true); | |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8427 print_free_block_coalesced(fc); |
| 0 | 8428 } else { // not in a free range and/or should not coalesce |
| 8429 // Return the current free range and start a new one. | |
| 8430 if (inFreeRange()) { | |
| 8431 // In a free range but cannot coalesce with the right hand chunk. | |
| 8432 // Put the current free range into the free lists. | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8433 flush_cur_free_chunk(freeFinger(), |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8434 pointer_delta(fc_addr, freeFinger())); |
| 0 | 8435 } |
| 8436 // Set up for new free range. Pass along whether the right hand | |
| 8437 // chunk is in the free lists. | |
| 8438 initialize_free_range((HeapWord*)fc, fcInFreeLists); | |
| 8439 } | |
| 8440 } | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8441 |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8442 // Lookahead flush: |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8443 // If we are tracking a free range, and this is the last chunk that |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8444 // 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
|
8445 // 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
|
8446 // 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
|
8447 // 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
|
8448 // 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
|
8449 // the previous end of the space when this cycle started, and |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8450 // a subsequent heap expansion caused the previously co-terminal |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8451 // free block to be coalesced with the newly expanded portion, |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8452 // thus rendering _limit a non-block-boundary making it dangerous |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8453 // for the sweeper to step over and examine. |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8454 void SweepClosure::lookahead_and_flush(FreeChunk* fc, size_t chunk_size) { |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8455 assert(inFreeRange(), "Should only be called if currently in a free range."); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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|
8456 HeapWord* const eob = ((HeapWord*)fc) + chunk_size; |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8457 assert(_sp->used_region().contains(eob - 1), |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8458 err_msg("eob = " PTR_FORMAT " out of bounds wrt _sp = [" PTR_FORMAT "," PTR_FORMAT ")" |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8459 " when examining fc = " PTR_FORMAT "(" SIZE_FORMAT ")", |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8460 _limit, _sp->bottom(), _sp->end(), fc, chunk_size)); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8461 if (eob >= _limit) { |
|
6028
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jmasa
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6026
diff
changeset
|
8462 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
|
8463 if (CMSTraceSweeper) { |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8464 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
|
8465 "[" PTR_FORMAT "," PTR_FORMAT ") in space " |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8466 "[" PTR_FORMAT "," PTR_FORMAT ")", |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8467 _limit, fc, eob, _sp->bottom(), _sp->end()); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
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|
8468 } |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
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changeset
|
8469 // 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
diff
changeset
|
8470 if (CMSTraceSweeper) { |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8471 gclog_or_tty->print_cr("Flushing ... "); |
|
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|
8472 } |
|
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|
8473 assert(freeFinger() < eob, "Error"); |
|
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|
8474 flush_cur_free_chunk( freeFinger(), pointer_delta(eob, freeFinger())); |
|
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|
8475 } |
|
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|
8476 } |
|
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|
8477 |
|
2132
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|
8478 void SweepClosure::flush_cur_free_chunk(HeapWord* chunk, size_t size) { |
| 0 | 8479 assert(inFreeRange(), "Should only be called if currently in a free range."); |
| 8480 assert(size > 0, | |
| 8481 "A zero sized chunk cannot be added to the free lists."); | |
| 8482 if (!freeRangeInFreeLists()) { | |
|
2132
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|
8483 if (CMSTestInFreeList) { |
| 0 | 8484 FreeChunk* fc = (FreeChunk*) chunk; |
|
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|
8485 fc->set_size(size); |
|
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|
8486 assert(!_sp->verify_chunk_in_free_list(fc), |
| 0 | 8487 "chunk should not be in free lists yet"); |
| 8488 } | |
| 8489 if (CMSTraceSweeper) { | |
| 8490 gclog_or_tty->print_cr(" -- add free block 0x%x (%d) to free lists", | |
| 8491 chunk, size); | |
| 8492 } | |
| 8493 // A new free range is going to be starting. The current | |
| 8494 // free range has not been added to the free lists yet or | |
| 8495 // was removed so add it back. | |
| 8496 // If the current free range was coalesced, then the death | |
| 8497 // of the free range was recorded. Record a birth now. | |
| 8498 if (lastFreeRangeCoalesced()) { | |
| 8499 _sp->coalBirth(size); | |
| 8500 } | |
| 8501 _sp->addChunkAndRepairOffsetTable(chunk, size, | |
| 8502 lastFreeRangeCoalesced()); | |
|
3746
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|
8503 } else if (CMSTraceSweeper) { |
|
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|
8504 gclog_or_tty->print_cr("Already in free list: nothing to flush"); |
| 0 | 8505 } |
| 8506 set_inFreeRange(false); | |
| 8507 set_freeRangeInFreeLists(false); | |
| 8508 } | |
| 8509 | |
| 8510 // We take a break if we've been at this for a while, | |
| 8511 // so as to avoid monopolizing the locks involved. | |
| 8512 void SweepClosure::do_yield_work(HeapWord* addr) { | |
| 8513 // Return current free chunk being used for coalescing (if any) | |
| 8514 // to the appropriate freelist. After yielding, the next | |
| 8515 // free block encountered will start a coalescing range of | |
| 8516 // free blocks. If the next free block is adjacent to the | |
| 8517 // chunk just flushed, they will need to wait for the next | |
| 8518 // sweep to be coalesced. | |
| 8519 if (inFreeRange()) { | |
|
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|
8520 flush_cur_free_chunk(freeFinger(), pointer_delta(addr, freeFinger())); |
| 0 | 8521 } |
| 8522 | |
| 8523 // First give up the locks, then yield, then re-lock. | |
| 8524 // We should probably use a constructor/destructor idiom to | |
| 8525 // do this unlock/lock or modify the MutexUnlocker class to | |
| 8526 // serve our purpose. XXX | |
| 8527 assert_lock_strong(_bitMap->lock()); | |
| 8528 assert_lock_strong(_freelistLock); | |
| 8529 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 8530 "CMS thread should hold CMS token"); | |
| 8531 _bitMap->lock()->unlock(); | |
| 8532 _freelistLock->unlock(); | |
| 8533 ConcurrentMarkSweepThread::desynchronize(true); | |
| 8534 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 8535 _collector->stopTimer(); | |
| 8536 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 8537 if (PrintCMSStatistics != 0) { | |
| 8538 _collector->incrementYields(); | |
| 8539 } | |
| 8540 _collector->icms_wait(); | |
| 8541 | |
| 8542 // See the comment in coordinator_yield() | |
| 8543 for (unsigned i = 0; i < CMSYieldSleepCount && | |
| 8544 ConcurrentMarkSweepThread::should_yield() && | |
| 8545 !CMSCollector::foregroundGCIsActive(); ++i) { | |
| 8546 os::sleep(Thread::current(), 1, false); | |
| 8547 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 8548 } | |
| 8549 | |
| 8550 ConcurrentMarkSweepThread::synchronize(true); | |
| 8551 _freelistLock->lock(); | |
| 8552 _bitMap->lock()->lock_without_safepoint_check(); | |
| 8553 _collector->startTimer(); | |
| 8554 } | |
| 8555 | |
| 8556 #ifndef PRODUCT | |
| 8557 // This is actually very useful in a product build if it can | |
| 8558 // be called from the debugger. Compile it into the product | |
| 8559 // as needed. | |
|
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|
8560 bool debug_verify_chunk_in_free_list(FreeChunk* fc) { |
|
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|
8561 return debug_cms_space->verify_chunk_in_free_list(fc); |
| 0 | 8562 } |
|
3746
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|
8563 #endif |
|
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|
8564 |
|
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|
8565 void SweepClosure::print_free_block_coalesced(FreeChunk* fc) const { |
| 0 | 8566 if (CMSTraceSweeper) { |
|
3746
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|
8567 gclog_or_tty->print_cr("Sweep:coal_free_blk " PTR_FORMAT " (" SIZE_FORMAT ")", |
|
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|
8568 fc, fc->size()); |
|
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|
8569 } |
|
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|
8570 } |
| 0 | 8571 |
| 8572 // CMSIsAliveClosure | |
| 8573 bool CMSIsAliveClosure::do_object_b(oop obj) { | |
| 8574 HeapWord* addr = (HeapWord*)obj; | |
| 8575 return addr != NULL && | |
| 8576 (!_span.contains(addr) || _bit_map->isMarked(addr)); | |
| 8577 } | |
| 8578 | |
|
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|
8579 |
| 935 | 8580 CMSKeepAliveClosure::CMSKeepAliveClosure( CMSCollector* collector, |
| 8581 MemRegion span, | |
| 8582 CMSBitMap* bit_map, CMSMarkStack* mark_stack, | |
|
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|
8583 bool cpc): |
|
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|
8584 _collector(collector), |
| 935 | 8585 _span(span), |
| 8586 _bit_map(bit_map), | |
| 8587 _mark_stack(mark_stack), | |
| 8588 _concurrent_precleaning(cpc) { | |
| 8589 assert(!_span.is_empty(), "Empty span could spell trouble"); | |
| 8590 } | |
| 8591 | |
| 8592 | |
| 0 | 8593 // CMSKeepAliveClosure: the serial version |
|
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|
8594 void CMSKeepAliveClosure::do_oop(oop obj) { |
|
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|
8595 HeapWord* addr = (HeapWord*)obj; |
| 0 | 8596 if (_span.contains(addr) && |
| 8597 !_bit_map->isMarked(addr)) { | |
| 8598 _bit_map->mark(addr); | |
| 8599 bool simulate_overflow = false; | |
| 8600 NOT_PRODUCT( | |
| 8601 if (CMSMarkStackOverflowALot && | |
| 8602 _collector->simulate_overflow()) { | |
| 8603 // simulate a stack overflow | |
| 8604 simulate_overflow = true; | |
| 8605 } | |
| 8606 ) | |
|
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|
8607 if (simulate_overflow || !_mark_stack->push(obj)) { |
|
452
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|
8608 if (_concurrent_precleaning) { |
|
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|
8609 // We dirty the overflown object and let the remark |
|
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|
8610 // phase deal with it. |
|
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|
8611 assert(_collector->overflow_list_is_empty(), "Error"); |
|
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|
8612 // In the case of object arrays, we need to dirty all of |
|
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|
8613 // the cards that the object spans. No locking or atomics |
|
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|
8614 // are needed since no one else can be mutating the mod union |
|
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|
8615 // table. |
|
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|
8616 if (obj->is_objArray()) { |
|
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|
8617 size_t sz = obj->size(); |
|
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|
8618 HeapWord* end_card_addr = |
|
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|
8619 (HeapWord*)round_to((intptr_t)(addr+sz), CardTableModRefBS::card_size); |
|
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|
8620 MemRegion redirty_range = MemRegion(addr, end_card_addr); |
|
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|
8621 assert(!redirty_range.is_empty(), "Arithmetical tautology"); |
|
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|
8622 _collector->_modUnionTable.mark_range(redirty_range); |
|
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|
8623 } else { |
|
00b023ae2d78
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|
8624 _collector->_modUnionTable.mark(addr); |
|
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|
8625 } |
|
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|
8626 _collector->_ser_kac_preclean_ovflw++; |
|
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|
8627 } else { |
|
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|
8628 _collector->push_on_overflow_list(obj); |
|
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|
8629 _collector->_ser_kac_ovflw++; |
|
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|
8630 } |
| 0 | 8631 } |
| 8632 } | |
| 8633 } | |
| 8634 | |
|
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|
8635 void CMSKeepAliveClosure::do_oop(oop* p) { CMSKeepAliveClosure::do_oop_work(p); } |
|
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|
8636 void CMSKeepAliveClosure::do_oop(narrowOop* p) { CMSKeepAliveClosure::do_oop_work(p); } |
|
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|
8637 |
| 0 | 8638 // CMSParKeepAliveClosure: a parallel version of the above. |
| 8639 // The work queues are private to each closure (thread), | |
| 8640 // but (may be) available for stealing by other threads. | |
|
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|
8641 void CMSParKeepAliveClosure::do_oop(oop obj) { |
|
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|
8642 HeapWord* addr = (HeapWord*)obj; |
| 0 | 8643 if (_span.contains(addr) && |
| 8644 !_bit_map->isMarked(addr)) { | |
| 8645 // In general, during recursive tracing, several threads | |
| 8646 // may be concurrently getting here; the first one to | |
| 8647 // "tag" it, claims it. | |
| 8648 if (_bit_map->par_mark(addr)) { | |
|
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|
8649 bool res = _work_queue->push(obj); |
| 0 | 8650 assert(res, "Low water mark should be much less than capacity"); |
| 8651 // Do a recursive trim in the hope that this will keep | |
| 8652 // stack usage lower, but leave some oops for potential stealers | |
| 8653 trim_queue(_low_water_mark); | |
| 8654 } // Else, another thread got there first | |
| 8655 } | |
| 8656 } | |
| 8657 | |
|
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|
8658 void CMSParKeepAliveClosure::do_oop(oop* p) { CMSParKeepAliveClosure::do_oop_work(p); } |
|
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|
8659 void CMSParKeepAliveClosure::do_oop(narrowOop* p) { CMSParKeepAliveClosure::do_oop_work(p); } |
|
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|
8660 |
| 0 | 8661 void CMSParKeepAliveClosure::trim_queue(uint max) { |
| 8662 while (_work_queue->size() > max) { | |
| 8663 oop new_oop; | |
| 8664 if (_work_queue->pop_local(new_oop)) { | |
| 8665 assert(new_oop != NULL && new_oop->is_oop(), "Expected an oop"); | |
| 8666 assert(_bit_map->isMarked((HeapWord*)new_oop), | |
| 8667 "no white objects on this stack!"); | |
| 8668 assert(_span.contains((HeapWord*)new_oop), "Out of bounds oop"); | |
| 8669 // iterate over the oops in this oop, marking and pushing | |
| 8670 // the ones in CMS heap (i.e. in _span). | |
| 8671 new_oop->oop_iterate(&_mark_and_push); | |
| 8672 } | |
| 8673 } | |
| 8674 } | |
| 8675 | |
| 935 | 8676 CMSInnerParMarkAndPushClosure::CMSInnerParMarkAndPushClosure( |
| 8677 CMSCollector* collector, | |
| 8678 MemRegion span, CMSBitMap* bit_map, | |
| 8679 OopTaskQueue* work_queue): | |
|
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|
8680 _collector(collector), |
| 935 | 8681 _span(span), |
| 8682 _bit_map(bit_map), | |
| 8683 _work_queue(work_queue) { } | |
| 8684 | |
|
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|
8685 void CMSInnerParMarkAndPushClosure::do_oop(oop obj) { |
|
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|
8686 HeapWord* addr = (HeapWord*)obj; |
| 0 | 8687 if (_span.contains(addr) && |
| 8688 !_bit_map->isMarked(addr)) { | |
| 8689 if (_bit_map->par_mark(addr)) { | |
| 8690 bool simulate_overflow = false; | |
| 8691 NOT_PRODUCT( | |
| 8692 if (CMSMarkStackOverflowALot && | |
| 8693 _collector->par_simulate_overflow()) { | |
| 8694 // simulate a stack overflow | |
| 8695 simulate_overflow = true; | |
| 8696 } | |
| 8697 ) | |
|
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|
8698 if (simulate_overflow || !_work_queue->push(obj)) { |
|
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|
8699 _collector->par_push_on_overflow_list(obj); |
| 0 | 8700 _collector->_par_kac_ovflw++; |
| 8701 } | |
| 8702 } // Else another thread got there already | |
| 8703 } | |
| 8704 } | |
| 8705 | |
|
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|
8706 void CMSInnerParMarkAndPushClosure::do_oop(oop* p) { CMSInnerParMarkAndPushClosure::do_oop_work(p); } |
|
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|
8707 void CMSInnerParMarkAndPushClosure::do_oop(narrowOop* p) { CMSInnerParMarkAndPushClosure::do_oop_work(p); } |
|
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|
8708 |
| 0 | 8709 ////////////////////////////////////////////////////////////////// |
| 8710 // CMSExpansionCause ///////////////////////////// | |
| 8711 ////////////////////////////////////////////////////////////////// | |
| 8712 const char* CMSExpansionCause::to_string(CMSExpansionCause::Cause cause) { | |
| 8713 switch (cause) { | |
| 8714 case _no_expansion: | |
| 8715 return "No expansion"; | |
| 8716 case _satisfy_free_ratio: | |
| 8717 return "Free ratio"; | |
| 8718 case _satisfy_promotion: | |
| 8719 return "Satisfy promotion"; | |
| 8720 case _satisfy_allocation: | |
| 8721 return "allocation"; | |
| 8722 case _allocate_par_lab: | |
| 8723 return "Par LAB"; | |
| 8724 case _allocate_par_spooling_space: | |
| 8725 return "Par Spooling Space"; | |
| 8726 case _adaptive_size_policy: | |
| 8727 return "Ergonomics"; | |
| 8728 default: | |
| 8729 return "unknown"; | |
| 8730 } | |
| 8731 } | |
| 8732 | |
| 8733 void CMSDrainMarkingStackClosure::do_void() { | |
| 8734 // the max number to take from overflow list at a time | |
| 8735 const size_t num = _mark_stack->capacity()/4; | |
|
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8736 assert(!_concurrent_precleaning || _collector->overflow_list_is_empty(), |
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8737 "Overflow list should be NULL during concurrent phases"); |
| 0 | 8738 while (!_mark_stack->isEmpty() || |
| 8739 // if stack is empty, check the overflow list | |
| 8740 _collector->take_from_overflow_list(num, _mark_stack)) { | |
|
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8741 oop obj = _mark_stack->pop(); |
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8742 HeapWord* addr = (HeapWord*)obj; |
| 0 | 8743 assert(_span.contains(addr), "Should be within span"); |
| 8744 assert(_bit_map->isMarked(addr), "Should be marked"); | |
|
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8745 assert(obj->is_oop(), "Should be an oop"); |
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8746 obj->oop_iterate(_keep_alive); |
| 0 | 8747 } |
| 8748 } | |
| 8749 | |
| 8750 void CMSParDrainMarkingStackClosure::do_void() { | |
| 8751 // drain queue | |
| 8752 trim_queue(0); | |
| 8753 } | |
| 8754 | |
| 8755 // Trim our work_queue so its length is below max at return | |
| 8756 void CMSParDrainMarkingStackClosure::trim_queue(uint max) { | |
| 8757 while (_work_queue->size() > max) { | |
| 8758 oop new_oop; | |
| 8759 if (_work_queue->pop_local(new_oop)) { | |
| 8760 assert(new_oop->is_oop(), "Expected an oop"); | |
| 8761 assert(_bit_map->isMarked((HeapWord*)new_oop), | |
| 8762 "no white objects on this stack!"); | |
| 8763 assert(_span.contains((HeapWord*)new_oop), "Out of bounds oop"); | |
| 8764 // iterate over the oops in this oop, marking and pushing | |
| 8765 // the ones in CMS heap (i.e. in _span). | |
| 8766 new_oop->oop_iterate(&_mark_and_push); | |
| 8767 } | |
| 8768 } | |
| 8769 } | |
| 8770 | |
| 8771 //////////////////////////////////////////////////////////////////// | |
| 8772 // Support for Marking Stack Overflow list handling and related code | |
| 8773 //////////////////////////////////////////////////////////////////// | |
| 8774 // Much of the following code is similar in shape and spirit to the | |
| 8775 // code used in ParNewGC. We should try and share that code | |
| 8776 // as much as possible in the future. | |
| 8777 | |
| 8778 #ifndef PRODUCT | |
| 8779 // Debugging support for CMSStackOverflowALot | |
| 8780 | |
| 8781 // It's OK to call this multi-threaded; the worst thing | |
| 8782 // that can happen is that we'll get a bunch of closely | |
| 8783 // spaced simulated oveflows, but that's OK, in fact | |
| 8784 // probably good as it would exercise the overflow code | |
| 8785 // under contention. | |
| 8786 bool CMSCollector::simulate_overflow() { | |
| 8787 if (_overflow_counter-- <= 0) { // just being defensive | |
| 8788 _overflow_counter = CMSMarkStackOverflowInterval; | |
| 8789 return true; | |
| 8790 } else { | |
| 8791 return false; | |
| 8792 } | |
| 8793 } | |
| 8794 | |
| 8795 bool CMSCollector::par_simulate_overflow() { | |
| 8796 return simulate_overflow(); | |
| 8797 } | |
| 8798 #endif | |
| 8799 | |
| 8800 // Single-threaded | |
| 8801 bool CMSCollector::take_from_overflow_list(size_t num, CMSMarkStack* stack) { | |
| 8802 assert(stack->isEmpty(), "Expected precondition"); | |
| 8803 assert(stack->capacity() > num, "Shouldn't bite more than can chew"); | |
| 8804 size_t i = num; | |
| 8805 oop cur = _overflow_list; | |
| 8806 const markOop proto = markOopDesc::prototype(); | |
| 534 | 8807 NOT_PRODUCT(ssize_t n = 0;) |
| 0 | 8808 for (oop next; i > 0 && cur != NULL; cur = next, i--) { |
| 8809 next = oop(cur->mark()); | |
| 8810 cur->set_mark(proto); // until proven otherwise | |
| 8811 assert(cur->is_oop(), "Should be an oop"); | |
| 8812 bool res = stack->push(cur); | |
| 8813 assert(res, "Bit off more than can chew?"); | |
| 8814 NOT_PRODUCT(n++;) | |
| 8815 } | |
| 8816 _overflow_list = cur; | |
| 8817 #ifndef PRODUCT | |
| 8818 assert(_num_par_pushes >= n, "Too many pops?"); | |
| 8819 _num_par_pushes -=n; | |
| 8820 #endif | |
| 8821 return !stack->isEmpty(); | |
| 8822 } | |
| 8823 | |
| 534 | 8824 #define BUSY (oop(0x1aff1aff)) |
| 8825 // (MT-safe) Get a prefix of at most "num" from the list. | |
| 8826 // The overflow list is chained through the mark word of | |
| 8827 // each object in the list. We fetch the entire list, | |
| 8828 // break off a prefix of the right size and return the | |
| 8829 // remainder. If other threads try to take objects from | |
| 8830 // the overflow list at that time, they will wait for | |
| 8831 // some time to see if data becomes available. If (and | |
| 8832 // only if) another thread places one or more object(s) | |
| 8833 // on the global list before we have returned the suffix | |
| 8834 // to the global list, we will walk down our local list | |
| 8835 // to find its end and append the global list to | |
| 8836 // our suffix before returning it. This suffix walk can | |
| 8837 // prove to be expensive (quadratic in the amount of traffic) | |
| 8838 // when there are many objects in the overflow list and | |
| 8839 // there is much producer-consumer contention on the list. | |
| 8840 // *NOTE*: The overflow list manipulation code here and | |
| 8841 // in ParNewGeneration:: are very similar in shape, | |
| 8842 // except that in the ParNew case we use the old (from/eden) | |
| 8843 // copy of the object to thread the list via its klass word. | |
| 8844 // Because of the common code, if you make any changes in | |
| 8845 // the code below, please check the ParNew version to see if | |
| 8846 // similar changes might be needed. | |
| 8847 // CR 6797058 has been filed to consolidate the common code. | |
| 0 | 8848 bool CMSCollector::par_take_from_overflow_list(size_t num, |
|
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8849 OopTaskQueue* work_q, |
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8850 int no_of_gc_threads) { |
| 534 | 8851 assert(work_q->size() == 0, "First empty local work queue"); |
| 0 | 8852 assert(num < work_q->max_elems(), "Can't bite more than we can chew"); |
| 8853 if (_overflow_list == NULL) { | |
| 8854 return false; | |
| 8855 } | |
| 8856 // Grab the entire list; we'll put back a suffix | |
| 534 | 8857 oop prefix = (oop)Atomic::xchg_ptr(BUSY, &_overflow_list); |
| 8858 Thread* tid = Thread::current(); | |
|
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8859 // Before "no_of_gc_threads" was introduced CMSOverflowSpinCount was |
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8860 // set to ParallelGCThreads. |
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8861 size_t CMSOverflowSpinCount = (size_t) no_of_gc_threads; // was ParallelGCThreads; |
| 534 | 8862 size_t sleep_time_millis = MAX2((size_t)1, num/100); |
| 8863 // If the list is busy, we spin for a short while, | |
| 8864 // sleeping between attempts to get the list. | |
| 8865 for (size_t spin = 0; prefix == BUSY && spin < CMSOverflowSpinCount; spin++) { | |
| 8866 os::sleep(tid, sleep_time_millis, false); | |
| 8867 if (_overflow_list == NULL) { | |
| 8868 // Nothing left to take | |
| 8869 return false; | |
| 8870 } else if (_overflow_list != BUSY) { | |
| 8871 // Try and grab the prefix | |
| 8872 prefix = (oop)Atomic::xchg_ptr(BUSY, &_overflow_list); | |
| 8873 } | |
| 8874 } | |
| 8875 // If the list was found to be empty, or we spun long | |
| 8876 // enough, we give up and return empty-handed. If we leave | |
| 8877 // the list in the BUSY state below, it must be the case that | |
| 8878 // some other thread holds the overflow list and will set it | |
| 8879 // to a non-BUSY state in the future. | |
| 8880 if (prefix == NULL || prefix == BUSY) { | |
| 8881 // Nothing to take or waited long enough | |
| 8882 if (prefix == NULL) { | |
| 8883 // Write back the NULL in case we overwrote it with BUSY above | |
| 8884 // and it is still the same value. | |
| 8885 (void) Atomic::cmpxchg_ptr(NULL, &_overflow_list, BUSY); | |
| 8886 } | |
| 8887 return false; | |
| 8888 } | |
| 8889 assert(prefix != NULL && prefix != BUSY, "Error"); | |
| 0 | 8890 size_t i = num; |
| 8891 oop cur = prefix; | |
| 534 | 8892 // Walk down the first "num" objects, unless we reach the end. |
| 0 | 8893 for (; i > 1 && cur->mark() != NULL; cur = oop(cur->mark()), i--); |
| 534 | 8894 if (cur->mark() == NULL) { |
| 8895 // We have "num" or fewer elements in the list, so there | |
| 8896 // is nothing to return to the global list. | |
| 8897 // Write back the NULL in lieu of the BUSY we wrote | |
| 8898 // above, if it is still the same value. | |
| 8899 if (_overflow_list == BUSY) { | |
| 8900 (void) Atomic::cmpxchg_ptr(NULL, &_overflow_list, BUSY); | |
| 8901 } | |
| 8902 } else { | |
| 8903 // Chop off the suffix and rerturn it to the global list. | |
| 8904 assert(cur->mark() != BUSY, "Error"); | |
| 0 | 8905 oop suffix_head = cur->mark(); // suffix will be put back on global list |
| 8906 cur->set_mark(NULL); // break off suffix | |
| 534 | 8907 // It's possible that the list is still in the empty(busy) state |
| 8908 // we left it in a short while ago; in that case we may be | |
| 8909 // able to place back the suffix without incurring the cost | |
| 8910 // of a walk down the list. | |
| 0 | 8911 oop observed_overflow_list = _overflow_list; |
| 534 | 8912 oop cur_overflow_list = observed_overflow_list; |
| 8913 bool attached = false; | |
| 8914 while (observed_overflow_list == BUSY || observed_overflow_list == NULL) { | |
| 0 | 8915 observed_overflow_list = |
| 534 | 8916 (oop) Atomic::cmpxchg_ptr(suffix_head, &_overflow_list, cur_overflow_list); |
| 8917 if (cur_overflow_list == observed_overflow_list) { | |
| 8918 attached = true; | |
| 8919 break; | |
| 8920 } else cur_overflow_list = observed_overflow_list; | |
| 8921 } | |
| 8922 if (!attached) { | |
| 8923 // Too bad, someone else sneaked in (at least) an element; we'll need | |
| 8924 // to do a splice. Find tail of suffix so we can prepend suffix to global | |
| 8925 // list. | |
| 8926 for (cur = suffix_head; cur->mark() != NULL; cur = (oop)(cur->mark())); | |
| 8927 oop suffix_tail = cur; | |
| 8928 assert(suffix_tail != NULL && suffix_tail->mark() == NULL, | |
| 8929 "Tautology"); | |
| 8930 observed_overflow_list = _overflow_list; | |
| 8931 do { | |
| 8932 cur_overflow_list = observed_overflow_list; | |
| 8933 if (cur_overflow_list != BUSY) { | |
| 8934 // Do the splice ... | |
| 8935 suffix_tail->set_mark(markOop(cur_overflow_list)); | |
| 8936 } else { // cur_overflow_list == BUSY | |
| 8937 suffix_tail->set_mark(NULL); | |
| 8938 } | |
| 8939 // ... and try to place spliced list back on overflow_list ... | |
| 8940 observed_overflow_list = | |
| 8941 (oop) Atomic::cmpxchg_ptr(suffix_head, &_overflow_list, cur_overflow_list); | |
| 8942 } while (cur_overflow_list != observed_overflow_list); | |
| 8943 // ... until we have succeeded in doing so. | |
| 8944 } | |
| 0 | 8945 } |
| 8946 | |
| 8947 // Push the prefix elements on work_q | |
| 8948 assert(prefix != NULL, "control point invariant"); | |
| 8949 const markOop proto = markOopDesc::prototype(); | |
| 8950 oop next; | |
| 534 | 8951 NOT_PRODUCT(ssize_t n = 0;) |
| 0 | 8952 for (cur = prefix; cur != NULL; cur = next) { |
| 8953 next = oop(cur->mark()); | |
| 8954 cur->set_mark(proto); // until proven otherwise | |
| 8955 assert(cur->is_oop(), "Should be an oop"); | |
| 8956 bool res = work_q->push(cur); | |
| 8957 assert(res, "Bit off more than we can chew?"); | |
| 8958 NOT_PRODUCT(n++;) | |
| 8959 } | |
| 8960 #ifndef PRODUCT | |
| 8961 assert(_num_par_pushes >= n, "Too many pops?"); | |
| 8962 Atomic::add_ptr(-(intptr_t)n, &_num_par_pushes); | |
| 8963 #endif | |
| 8964 return true; | |
| 8965 } | |
| 8966 | |
| 8967 // Single-threaded | |
| 8968 void CMSCollector::push_on_overflow_list(oop p) { | |
| 8969 NOT_PRODUCT(_num_par_pushes++;) | |
| 8970 assert(p->is_oop(), "Not an oop"); | |
| 8971 preserve_mark_if_necessary(p); | |
| 8972 p->set_mark((markOop)_overflow_list); | |
| 8973 _overflow_list = p; | |
| 8974 } | |
| 8975 | |
| 8976 // Multi-threaded; use CAS to prepend to overflow list | |
| 8977 void CMSCollector::par_push_on_overflow_list(oop p) { | |
| 8978 NOT_PRODUCT(Atomic::inc_ptr(&_num_par_pushes);) | |
| 8979 assert(p->is_oop(), "Not an oop"); | |
| 8980 par_preserve_mark_if_necessary(p); | |
| 8981 oop observed_overflow_list = _overflow_list; | |
| 8982 oop cur_overflow_list; | |
| 8983 do { | |
| 8984 cur_overflow_list = observed_overflow_list; | |
| 534 | 8985 if (cur_overflow_list != BUSY) { |
| 8986 p->set_mark(markOop(cur_overflow_list)); | |
| 8987 } else { | |
| 8988 p->set_mark(NULL); | |
| 8989 } | |
| 0 | 8990 observed_overflow_list = |
| 8991 (oop) Atomic::cmpxchg_ptr(p, &_overflow_list, cur_overflow_list); | |
| 8992 } while (cur_overflow_list != observed_overflow_list); | |
| 8993 } | |
| 534 | 8994 #undef BUSY |
| 0 | 8995 |
| 8996 // Single threaded | |
| 8997 // General Note on GrowableArray: pushes may silently fail | |
| 8998 // because we are (temporarily) out of C-heap for expanding | |
| 8999 // the stack. The problem is quite ubiquitous and affects | |
| 9000 // a lot of code in the JVM. The prudent thing for GrowableArray | |
| 9001 // to do (for now) is to exit with an error. However, that may | |
| 9002 // be too draconian in some cases because the caller may be | |
| 534 | 9003 // able to recover without much harm. For such cases, we |
| 0 | 9004 // should probably introduce a "soft_push" method which returns |
| 9005 // an indication of success or failure with the assumption that | |
| 9006 // the caller may be able to recover from a failure; code in | |
| 9007 // the VM can then be changed, incrementally, to deal with such | |
| 9008 // failures where possible, thus, incrementally hardening the VM | |
| 9009 // in such low resource situations. | |
| 9010 void CMSCollector::preserve_mark_work(oop p, markOop m) { | |
|
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9011 _preserved_oop_stack.push(p); |
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9012 _preserved_mark_stack.push(m); |
| 0 | 9013 assert(m == p->mark(), "Mark word changed"); |
|
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9014 assert(_preserved_oop_stack.size() == _preserved_mark_stack.size(), |
| 0 | 9015 "bijection"); |
| 9016 } | |
| 9017 | |
| 9018 // Single threaded | |
| 9019 void CMSCollector::preserve_mark_if_necessary(oop p) { | |
| 9020 markOop m = p->mark(); | |
| 9021 if (m->must_be_preserved(p)) { | |
| 9022 preserve_mark_work(p, m); | |
| 9023 } | |
| 9024 } | |
| 9025 | |
| 9026 void CMSCollector::par_preserve_mark_if_necessary(oop p) { | |
| 9027 markOop m = p->mark(); | |
| 9028 if (m->must_be_preserved(p)) { | |
| 9029 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); | |
| 9030 // Even though we read the mark word without holding | |
| 9031 // the lock, we are assured that it will not change | |
| 9032 // because we "own" this oop, so no other thread can | |
| 9033 // be trying to push it on the overflow list; see | |
| 9034 // the assertion in preserve_mark_work() that checks | |
| 9035 // that m == p->mark(). | |
| 9036 preserve_mark_work(p, m); | |
| 9037 } | |
| 9038 } | |
| 9039 | |
| 9040 // We should be able to do this multi-threaded, | |
| 9041 // a chunk of stack being a task (this is | |
| 9042 // correct because each oop only ever appears | |
| 9043 // once in the overflow list. However, it's | |
| 9044 // not very easy to completely overlap this with | |
| 9045 // other operations, so will generally not be done | |
| 9046 // until all work's been completed. Because we | |
| 9047 // expect the preserved oop stack (set) to be small, | |
| 9048 // it's probably fine to do this single-threaded. | |
| 9049 // We can explore cleverer concurrent/overlapped/parallel | |
| 9050 // processing of preserved marks if we feel the | |
| 9051 // need for this in the future. Stack overflow should | |
| 9052 // be so rare in practice and, when it happens, its | |
| 9053 // effect on performance so great that this will | |
| 9054 // likely just be in the noise anyway. | |
| 9055 void CMSCollector::restore_preserved_marks_if_any() { | |
| 9056 assert(SafepointSynchronize::is_at_safepoint(), | |
| 9057 "world should be stopped"); | |
| 9058 assert(Thread::current()->is_ConcurrentGC_thread() || | |
| 9059 Thread::current()->is_VM_thread(), | |
| 9060 "should be single-threaded"); | |
|
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9061 assert(_preserved_oop_stack.size() == _preserved_mark_stack.size(), |
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9062 "bijection"); |
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9063 |
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9064 while (!_preserved_oop_stack.is_empty()) { |
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9065 oop p = _preserved_oop_stack.pop(); |
| 0 | 9066 assert(p->is_oop(), "Should be an oop"); |
| 9067 assert(_span.contains(p), "oop should be in _span"); | |
| 9068 assert(p->mark() == markOopDesc::prototype(), | |
| 9069 "Set when taken from overflow list"); | |
|
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9070 markOop m = _preserved_mark_stack.pop(); |
| 0 | 9071 p->set_mark(m); |
| 9072 } | |
|
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9073 assert(_preserved_mark_stack.is_empty() && _preserved_oop_stack.is_empty(), |
| 0 | 9074 "stacks were cleared above"); |
| 9075 } | |
| 9076 | |
| 9077 #ifndef PRODUCT | |
| 9078 bool CMSCollector::no_preserved_marks() const { | |
|
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9079 return _preserved_mark_stack.is_empty() && _preserved_oop_stack.is_empty(); |
| 0 | 9080 } |
| 9081 #endif | |
| 9082 | |
| 9083 CMSAdaptiveSizePolicy* ASConcurrentMarkSweepGeneration::cms_size_policy() const | |
| 9084 { | |
| 9085 GenCollectedHeap* gch = (GenCollectedHeap*) GenCollectedHeap::heap(); | |
| 9086 CMSAdaptiveSizePolicy* size_policy = | |
| 9087 (CMSAdaptiveSizePolicy*) gch->gen_policy()->size_policy(); | |
| 9088 assert(size_policy->is_gc_cms_adaptive_size_policy(), | |
| 9089 "Wrong type for size policy"); | |
| 9090 return size_policy; | |
| 9091 } | |
| 9092 | |
| 9093 void ASConcurrentMarkSweepGeneration::resize(size_t cur_promo_size, | |
| 9094 size_t desired_promo_size) { | |
| 9095 if (cur_promo_size < desired_promo_size) { | |
| 9096 size_t expand_bytes = desired_promo_size - cur_promo_size; | |
| 9097 if (PrintAdaptiveSizePolicy && Verbose) { | |
| 9098 gclog_or_tty->print_cr(" ASConcurrentMarkSweepGeneration::resize " | |
| 9099 "Expanding tenured generation by " SIZE_FORMAT " (bytes)", | |
| 9100 expand_bytes); | |
| 9101 } | |
| 9102 expand(expand_bytes, | |
| 9103 MinHeapDeltaBytes, | |
| 9104 CMSExpansionCause::_adaptive_size_policy); | |
| 9105 } else if (desired_promo_size < cur_promo_size) { | |
| 9106 size_t shrink_bytes = cur_promo_size - desired_promo_size; | |
| 9107 if (PrintAdaptiveSizePolicy && Verbose) { | |
| 9108 gclog_or_tty->print_cr(" ASConcurrentMarkSweepGeneration::resize " | |
| 9109 "Shrinking tenured generation by " SIZE_FORMAT " (bytes)", | |
| 9110 shrink_bytes); | |
| 9111 } | |
| 9112 shrink(shrink_bytes); | |
| 9113 } | |
| 9114 } | |
| 9115 | |
| 9116 CMSGCAdaptivePolicyCounters* ASConcurrentMarkSweepGeneration::gc_adaptive_policy_counters() { | |
| 9117 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 9118 CMSGCAdaptivePolicyCounters* counters = | |
| 9119 (CMSGCAdaptivePolicyCounters*) gch->collector_policy()->counters(); | |
| 9120 assert(counters->kind() == GCPolicyCounters::CMSGCAdaptivePolicyCountersKind, | |
| 9121 "Wrong kind of counters"); | |
| 9122 return counters; | |
| 9123 } | |
| 9124 | |
| 9125 | |
| 9126 void ASConcurrentMarkSweepGeneration::update_counters() { | |
| 9127 if (UsePerfData) { | |
| 9128 _space_counters->update_all(); | |
| 9129 _gen_counters->update_all(); | |
| 9130 CMSGCAdaptivePolicyCounters* counters = gc_adaptive_policy_counters(); | |
| 9131 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 9132 CMSGCStats* gc_stats_l = (CMSGCStats*) gc_stats(); | |
| 9133 assert(gc_stats_l->kind() == GCStats::CMSGCStatsKind, | |
| 9134 "Wrong gc statistics type"); | |
| 9135 counters->update_counters(gc_stats_l); | |
| 9136 } | |
| 9137 } | |
| 9138 | |
| 9139 void ASConcurrentMarkSweepGeneration::update_counters(size_t used) { | |
| 9140 if (UsePerfData) { | |
| 9141 _space_counters->update_used(used); | |
| 9142 _space_counters->update_capacity(); | |
| 9143 _gen_counters->update_all(); | |
| 9144 | |
| 9145 CMSGCAdaptivePolicyCounters* counters = gc_adaptive_policy_counters(); | |
| 9146 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 9147 CMSGCStats* gc_stats_l = (CMSGCStats*) gc_stats(); | |
| 9148 assert(gc_stats_l->kind() == GCStats::CMSGCStatsKind, | |
| 9149 "Wrong gc statistics type"); | |
| 9150 counters->update_counters(gc_stats_l); | |
| 9151 } | |
| 9152 } | |
| 9153 | |
| 9154 void ASConcurrentMarkSweepGeneration::shrink_by(size_t desired_bytes) { | |
| 9155 assert_locked_or_safepoint(Heap_lock); | |
| 9156 assert_lock_strong(freelistLock()); | |
| 9157 HeapWord* old_end = _cmsSpace->end(); | |
| 9158 HeapWord* unallocated_start = _cmsSpace->unallocated_block(); | |
| 9159 assert(old_end >= unallocated_start, "Miscalculation of unallocated_start"); | |
| 9160 FreeChunk* chunk_at_end = find_chunk_at_end(); | |
| 9161 if (chunk_at_end == NULL) { | |
| 9162 // No room to shrink | |
| 9163 if (PrintGCDetails && Verbose) { | |
| 9164 gclog_or_tty->print_cr("No room to shrink: old_end " | |
| 9165 PTR_FORMAT " unallocated_start " PTR_FORMAT | |
| 9166 " chunk_at_end " PTR_FORMAT, | |
| 9167 old_end, unallocated_start, chunk_at_end); | |
| 9168 } | |
| 9169 return; | |
| 9170 } else { | |
| 9171 | |
| 9172 // Find the chunk at the end of the space and determine | |
| 9173 // how much it can be shrunk. | |
| 9174 size_t shrinkable_size_in_bytes = chunk_at_end->size(); | |
| 9175 size_t aligned_shrinkable_size_in_bytes = | |
| 9176 align_size_down(shrinkable_size_in_bytes, os::vm_page_size()); | |
| 6885 | 9177 assert(unallocated_start <= (HeapWord*) chunk_at_end->end(), |
| 0 | 9178 "Inconsistent chunk at end of space"); |
| 9179 size_t bytes = MIN2(desired_bytes, aligned_shrinkable_size_in_bytes); | |
| 9180 size_t word_size_before = heap_word_size(_virtual_space.committed_size()); | |
| 9181 | |
| 9182 // Shrink the underlying space | |
| 9183 _virtual_space.shrink_by(bytes); | |
| 9184 if (PrintGCDetails && Verbose) { | |
| 9185 gclog_or_tty->print_cr("ConcurrentMarkSweepGeneration::shrink_by:" | |
| 9186 " desired_bytes " SIZE_FORMAT | |
| 9187 " shrinkable_size_in_bytes " SIZE_FORMAT | |
| 9188 " aligned_shrinkable_size_in_bytes " SIZE_FORMAT | |
| 9189 " bytes " SIZE_FORMAT, | |
| 9190 desired_bytes, shrinkable_size_in_bytes, | |
| 9191 aligned_shrinkable_size_in_bytes, bytes); | |
| 9192 gclog_or_tty->print_cr(" old_end " SIZE_FORMAT | |
| 9193 " unallocated_start " SIZE_FORMAT, | |
| 9194 old_end, unallocated_start); | |
| 9195 } | |
| 9196 | |
| 9197 // If the space did shrink (shrinking is not guaranteed), | |
| 9198 // shrink the chunk at the end by the appropriate amount. | |
| 9199 if (((HeapWord*)_virtual_space.high()) < old_end) { | |
| 9200 size_t new_word_size = | |
| 9201 heap_word_size(_virtual_space.committed_size()); | |
| 9202 | |
| 9203 // Have to remove the chunk from the dictionary because it is changing | |
| 9204 // size and might be someplace elsewhere in the dictionary. | |
| 9205 | |
| 9206 // Get the chunk at end, shrink it, and put it | |
| 9207 // back. | |
| 9208 _cmsSpace->removeChunkFromDictionary(chunk_at_end); | |
| 9209 size_t word_size_change = word_size_before - new_word_size; | |
| 9210 size_t chunk_at_end_old_size = chunk_at_end->size(); | |
| 9211 assert(chunk_at_end_old_size >= word_size_change, | |
| 9212 "Shrink is too large"); | |
|
6028
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
parents:
6026
diff
changeset
|
9213 chunk_at_end->set_size(chunk_at_end_old_size - |
| 0 | 9214 word_size_change); |
| 9215 _cmsSpace->freed((HeapWord*) chunk_at_end->end(), | |
| 9216 word_size_change); | |
| 9217 | |
| 9218 _cmsSpace->returnChunkToDictionary(chunk_at_end); | |
| 9219 | |
| 9220 MemRegion mr(_cmsSpace->bottom(), new_word_size); | |
| 9221 _bts->resize(new_word_size); // resize the block offset shared array | |
| 9222 Universe::heap()->barrier_set()->resize_covered_region(mr); | |
| 9223 _cmsSpace->assert_locked(); | |
| 9224 _cmsSpace->set_end((HeapWord*)_virtual_space.high()); | |
| 9225 | |
| 9226 NOT_PRODUCT(_cmsSpace->dictionary()->verify()); | |
| 9227 | |
| 9228 // update the space and generation capacity counters | |
| 9229 if (UsePerfData) { | |
| 9230 _space_counters->update_capacity(); | |
| 9231 _gen_counters->update_all(); | |
| 9232 } | |
| 9233 | |
| 9234 if (Verbose && PrintGCDetails) { | |
| 9235 size_t new_mem_size = _virtual_space.committed_size(); | |
| 9236 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
|
9237 gclog_or_tty->print_cr("Shrinking %s from " SIZE_FORMAT "K by " SIZE_FORMAT "K to " SIZE_FORMAT "K", |
| 0 | 9238 name(), old_mem_size/K, bytes/K, new_mem_size/K); |
| 9239 } | |
| 9240 } | |
| 9241 | |
| 9242 assert(_cmsSpace->unallocated_block() <= _cmsSpace->end(), | |
| 9243 "Inconsistency at end of space"); | |
| 6885 | 9244 assert(chunk_at_end->end() == (uintptr_t*) _cmsSpace->end(), |
| 0 | 9245 "Shrinking is inconsistent"); |
| 9246 return; | |
| 9247 } | |
| 9248 } | |
| 9249 | |
| 9250 // Transfer some number of overflown objects to usual marking | |
| 9251 // stack. Return true if some objects were transferred. | |
| 9252 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
|
9253 size_t num = MIN2((size_t)(_mark_stack->capacity() - _mark_stack->length())/4, |
| 0 | 9254 (size_t)ParGCDesiredObjsFromOverflowList); |
| 9255 | |
| 9256 bool res = _collector->take_from_overflow_list(num, _mark_stack); | |
| 9257 assert(_collector->overflow_list_is_empty() || res, | |
| 9258 "If list is not empty, we should have taken something"); | |
| 9259 assert(!res || !_mark_stack->isEmpty(), | |
| 9260 "If we took something, it should now be on our stack"); | |
| 9261 return res; | |
| 9262 } | |
| 9263 | |
| 9264 size_t MarkDeadObjectsClosure::do_blk(HeapWord* addr) { | |
| 9265 size_t res = _sp->block_size_no_stall(addr, _collector); | |
| 9266 if (_sp->block_is_obj(addr)) { | |
| 9267 if (_live_bit_map->isMarked(addr)) { | |
| 9268 // It can't have been dead in a previous cycle | |
| 9269 guarantee(!_dead_bit_map->isMarked(addr), "No resurrection!"); | |
| 9270 } else { | |
| 9271 _dead_bit_map->mark(addr); // mark the dead object | |
| 9272 } | |
| 9273 } | |
|
2226
c5a923563727
6912621: iCMS: Error: assert(_markBitMap.isMarked(addr + 1),"Missing Printezis bit?")
ysr
parents:
2177
diff
changeset
|
9274 // Could be 0, if the block size could not be computed without stalling. |
| 0 | 9275 return res; |
| 9276 } | |
|
1703
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9277 |
|
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
parents:
3293
diff
changeset
|
9278 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
|
9279 |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9280 switch (phase) { |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9281 case CMSCollector::InitialMarking: |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9282 initialize(true /* fullGC */ , |
|
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
parents:
3293
diff
changeset
|
9283 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
|
9284 true /* recordGCBeginTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9285 true /* recordPreGCUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9286 false /* recordPeakUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9287 false /* recordPostGCusage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9288 true /* recordAccumulatedGCTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9289 false /* recordGCEndTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9290 false /* countCollection */ ); |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9291 break; |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9292 |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9293 case CMSCollector::FinalMarking: |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9294 initialize(true /* fullGC */ , |
|
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
parents:
3293
diff
changeset
|
9295 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
|
9296 false /* recordGCBeginTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9297 false /* recordPreGCUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9298 false /* recordPeakUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9299 false /* recordPostGCusage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9300 true /* recordAccumulatedGCTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9301 false /* recordGCEndTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9302 false /* countCollection */ ); |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9303 break; |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9304 |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9305 case CMSCollector::Sweeping: |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9306 initialize(true /* fullGC */ , |
|
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
parents:
3293
diff
changeset
|
9307 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
|
9308 false /* recordGCBeginTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9309 false /* recordPreGCUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9310 true /* recordPeakUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9311 true /* recordPostGCusage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9312 false /* recordAccumulatedGCTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9313 true /* recordGCEndTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9314 true /* countCollection */ ); |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9315 break; |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9316 |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9317 default: |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9318 ShouldNotReachHere(); |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9319 } |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9320 } |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9321 |