Mercurial > hg > graal-compiler
annotate src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp @ 10405:f2110083203d
8005849: JEP 167: Event-Based JVM Tracing
Reviewed-by: acorn, coleenp, sla
Contributed-by: Karen Kinnear <karen.kinnear@oracle.com>, Bengt Rutisson <bengt.rutisson@oracle.com>, Calvin Cheung <calvin.cheung@oracle.com>, Erik Gahlin <erik.gahlin@oracle.com>, Erik Helin <erik.helin@oracle.com>, Jesper Wilhelmsson <jesper.wilhelmsson@oracle.com>, Keith McGuigan <keith.mcguigan@oracle.com>, Mattias Tobiasson <mattias.tobiasson@oracle.com>, Markus Gronlund <markus.gronlund@oracle.com>, Mikael Auno <mikael.auno@oracle.com>, Nils Eliasson <nils.eliasson@oracle.com>, Nils Loodin <nils.loodin@oracle.com>, Rickard Backman <rickard.backman@oracle.com>, Staffan Larsen <staffan.larsen@oracle.com>, Stefan Karlsson <stefan.karlsson@oracle.com>, Yekaterina Kantserova <yekaterina.kantserova@oracle.com>
| author | sla |
|---|---|
| date | Mon, 10 Jun 2013 11:30:51 +0200 |
| parents | 7c5a1b62f53d |
| children | 71180a6e5080 |
| rev | line source |
|---|---|
| 0 | 1 /* |
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2 * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved. |
| 0 | 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 4 * | |
| 5 * This code is free software; you can redistribute it and/or modify it | |
| 6 * under the terms of the GNU General Public License version 2 only, as | |
| 7 * published by the Free Software Foundation. | |
| 8 * | |
| 9 * This code is distributed in the hope that it will be useful, but WITHOUT | |
| 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 12 * version 2 for more details (a copy is included in the LICENSE file that | |
| 13 * accompanied this code). | |
| 14 * | |
| 15 * You should have received a copy of the GNU General Public License version | |
| 16 * 2 along with this work; if not, write to the Free Software Foundation, | |
| 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
| 18 * | |
|
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
| 0 | 22 * |
| 23 */ | |
| 24 | |
| 1972 | 25 #include "precompiled.hpp" |
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26 #include "classfile/classLoaderData.hpp" |
| 1972 | 27 #include "classfile/symbolTable.hpp" |
| 28 #include "classfile/systemDictionary.hpp" | |
| 29 #include "code/codeCache.hpp" | |
| 30 #include "gc_implementation/concurrentMarkSweep/cmsAdaptiveSizePolicy.hpp" | |
| 31 #include "gc_implementation/concurrentMarkSweep/cmsCollectorPolicy.hpp" | |
| 32 #include "gc_implementation/concurrentMarkSweep/cmsGCAdaptivePolicyCounters.hpp" | |
| 33 #include "gc_implementation/concurrentMarkSweep/cmsOopClosures.inline.hpp" | |
| 34 #include "gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.hpp" | |
| 35 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.inline.hpp" | |
| 36 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp" | |
| 37 #include "gc_implementation/concurrentMarkSweep/vmCMSOperations.hpp" | |
| 38 #include "gc_implementation/parNew/parNewGeneration.hpp" | |
| 39 #include "gc_implementation/shared/collectorCounters.hpp" | |
| 10405 | 40 #include "gc_implementation/shared/gcTimer.hpp" |
| 41 #include "gc_implementation/shared/gcTrace.hpp" | |
| 42 #include "gc_implementation/shared/gcTraceTime.hpp" | |
| 1972 | 43 #include "gc_implementation/shared/isGCActiveMark.hpp" |
| 44 #include "gc_interface/collectedHeap.inline.hpp" | |
| 10405 | 45 #include "memory/allocation.hpp" |
| 1972 | 46 #include "memory/cardTableRS.hpp" |
| 47 #include "memory/collectorPolicy.hpp" | |
| 48 #include "memory/gcLocker.inline.hpp" | |
| 49 #include "memory/genCollectedHeap.hpp" | |
| 50 #include "memory/genMarkSweep.hpp" | |
| 51 #include "memory/genOopClosures.inline.hpp" | |
| 52 #include "memory/iterator.hpp" | |
| 53 #include "memory/referencePolicy.hpp" | |
| 54 #include "memory/resourceArea.hpp" | |
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55 #include "memory/tenuredGeneration.hpp" |
| 1972 | 56 #include "oops/oop.inline.hpp" |
| 57 #include "prims/jvmtiExport.hpp" | |
| 58 #include "runtime/globals_extension.hpp" | |
| 59 #include "runtime/handles.inline.hpp" | |
| 60 #include "runtime/java.hpp" | |
| 61 #include "runtime/vmThread.hpp" | |
| 62 #include "services/memoryService.hpp" | |
| 63 #include "services/runtimeService.hpp" | |
| 0 | 64 |
| 65 // statics | |
| 66 CMSCollector* ConcurrentMarkSweepGeneration::_collector = NULL; | |
| 10405 | 67 bool CMSCollector::_full_gc_requested = false; |
| 68 GCCause::Cause CMSCollector::_full_gc_cause = GCCause::_no_gc; | |
| 0 | 69 |
| 70 ////////////////////////////////////////////////////////////////// | |
| 71 // In support of CMS/VM thread synchronization | |
| 72 ////////////////////////////////////////////////////////////////// | |
| 73 // We split use of the CGC_lock into 2 "levels". | |
| 74 // The low-level locking is of the usual CGC_lock monitor. We introduce | |
| 75 // a higher level "token" (hereafter "CMS token") built on top of the | |
| 76 // low level monitor (hereafter "CGC lock"). | |
| 77 // The token-passing protocol gives priority to the VM thread. The | |
| 78 // CMS-lock doesn't provide any fairness guarantees, but clients | |
| 79 // should ensure that it is only held for very short, bounded | |
| 80 // durations. | |
| 81 // | |
| 82 // When either of the CMS thread or the VM thread is involved in | |
| 83 // collection operations during which it does not want the other | |
| 84 // thread to interfere, it obtains the CMS token. | |
| 85 // | |
| 86 // If either thread tries to get the token while the other has | |
| 87 // it, that thread waits. However, if the VM thread and CMS thread | |
| 88 // both want the token, then the VM thread gets priority while the | |
| 89 // CMS thread waits. This ensures, for instance, that the "concurrent" | |
| 90 // phases of the CMS thread's work do not block out the VM thread | |
| 91 // for long periods of time as the CMS thread continues to hog | |
| 92 // the token. (See bug 4616232). | |
| 93 // | |
| 94 // The baton-passing functions are, however, controlled by the | |
| 95 // flags _foregroundGCShouldWait and _foregroundGCIsActive, | |
| 96 // and here the low-level CMS lock, not the high level token, | |
| 97 // ensures mutual exclusion. | |
| 98 // | |
| 99 // Two important conditions that we have to satisfy: | |
| 100 // 1. if a thread does a low-level wait on the CMS lock, then it | |
| 101 // relinquishes the CMS token if it were holding that token | |
| 102 // when it acquired the low-level CMS lock. | |
| 103 // 2. any low-level notifications on the low-level lock | |
| 104 // should only be sent when a thread has relinquished the token. | |
| 105 // | |
| 106 // In the absence of either property, we'd have potential deadlock. | |
| 107 // | |
| 108 // We protect each of the CMS (concurrent and sequential) phases | |
| 109 // with the CMS _token_, not the CMS _lock_. | |
| 110 // | |
| 111 // The only code protected by CMS lock is the token acquisition code | |
| 112 // itself, see ConcurrentMarkSweepThread::[de]synchronize(), and the | |
| 113 // baton-passing code. | |
| 114 // | |
| 115 // Unfortunately, i couldn't come up with a good abstraction to factor and | |
| 116 // hide the naked CGC_lock manipulation in the baton-passing code | |
| 117 // further below. That's something we should try to do. Also, the proof | |
| 118 // of correctness of this 2-level locking scheme is far from obvious, | |
| 119 // and potentially quite slippery. We have an uneasy supsicion, for instance, | |
| 120 // that there may be a theoretical possibility of delay/starvation in the | |
| 121 // low-level lock/wait/notify scheme used for the baton-passing because of | |
| 122 // potential intereference with the priority scheme embodied in the | |
| 123 // CMS-token-passing protocol. See related comments at a CGC_lock->wait() | |
| 124 // invocation further below and marked with "XXX 20011219YSR". | |
| 125 // Indeed, as we note elsewhere, this may become yet more slippery | |
| 126 // in the presence of multiple CMS and/or multiple VM threads. XXX | |
| 127 | |
| 128 class CMSTokenSync: public StackObj { | |
| 129 private: | |
| 130 bool _is_cms_thread; | |
| 131 public: | |
| 132 CMSTokenSync(bool is_cms_thread): | |
| 133 _is_cms_thread(is_cms_thread) { | |
| 134 assert(is_cms_thread == Thread::current()->is_ConcurrentGC_thread(), | |
| 135 "Incorrect argument to constructor"); | |
| 136 ConcurrentMarkSweepThread::synchronize(_is_cms_thread); | |
| 137 } | |
| 138 | |
| 139 ~CMSTokenSync() { | |
| 140 assert(_is_cms_thread ? | |
| 141 ConcurrentMarkSweepThread::cms_thread_has_cms_token() : | |
| 142 ConcurrentMarkSweepThread::vm_thread_has_cms_token(), | |
| 143 "Incorrect state"); | |
| 144 ConcurrentMarkSweepThread::desynchronize(_is_cms_thread); | |
| 145 } | |
| 146 }; | |
| 147 | |
| 148 // Convenience class that does a CMSTokenSync, and then acquires | |
| 149 // upto three locks. | |
| 150 class CMSTokenSyncWithLocks: public CMSTokenSync { | |
| 151 private: | |
| 152 // Note: locks are acquired in textual declaration order | |
| 153 // and released in the opposite order | |
| 154 MutexLockerEx _locker1, _locker2, _locker3; | |
| 155 public: | |
| 156 CMSTokenSyncWithLocks(bool is_cms_thread, Mutex* mutex1, | |
| 157 Mutex* mutex2 = NULL, Mutex* mutex3 = NULL): | |
| 158 CMSTokenSync(is_cms_thread), | |
| 159 _locker1(mutex1, Mutex::_no_safepoint_check_flag), | |
| 160 _locker2(mutex2, Mutex::_no_safepoint_check_flag), | |
| 161 _locker3(mutex3, Mutex::_no_safepoint_check_flag) | |
| 162 { } | |
| 163 }; | |
| 164 | |
| 165 | |
| 166 // Wrapper class to temporarily disable icms during a foreground cms collection. | |
| 167 class ICMSDisabler: public StackObj { | |
| 168 public: | |
| 169 // The ctor disables icms and wakes up the thread so it notices the change; | |
| 170 // the dtor re-enables icms. Note that the CMSCollector methods will check | |
| 171 // CMSIncrementalMode. | |
| 172 ICMSDisabler() { CMSCollector::disable_icms(); CMSCollector::start_icms(); } | |
| 173 ~ICMSDisabler() { CMSCollector::enable_icms(); } | |
| 174 }; | |
| 175 | |
| 176 ////////////////////////////////////////////////////////////////// | |
| 177 // Concurrent Mark-Sweep Generation ///////////////////////////// | |
| 178 ////////////////////////////////////////////////////////////////// | |
| 179 | |
| 180 NOT_PRODUCT(CompactibleFreeListSpace* debug_cms_space;) | |
| 181 | |
| 182 // This struct contains per-thread things necessary to support parallel | |
| 183 // young-gen collection. | |
| 6197 | 184 class CMSParGCThreadState: public CHeapObj<mtGC> { |
| 0 | 185 public: |
| 186 CFLS_LAB lab; | |
| 187 PromotionInfo promo; | |
| 188 | |
| 189 // Constructor. | |
| 190 CMSParGCThreadState(CompactibleFreeListSpace* cfls) : lab(cfls) { | |
| 191 promo.setSpace(cfls); | |
| 192 } | |
| 193 }; | |
| 194 | |
| 195 ConcurrentMarkSweepGeneration::ConcurrentMarkSweepGeneration( | |
| 196 ReservedSpace rs, size_t initial_byte_size, int level, | |
| 197 CardTableRS* ct, bool use_adaptive_freelists, | |
| 6026 | 198 FreeBlockDictionary<FreeChunk>::DictionaryChoice dictionaryChoice) : |
| 0 | 199 CardGeneration(rs, initial_byte_size, level, ct), |
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200 _dilatation_factor(((double)MinChunkSize)/((double)(CollectedHeap::min_fill_size()))), |
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201 _debug_collection_type(Concurrent_collection_type), |
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202 _did_compact(false) |
| 0 | 203 { |
| 204 HeapWord* bottom = (HeapWord*) _virtual_space.low(); | |
| 205 HeapWord* end = (HeapWord*) _virtual_space.high(); | |
| 206 | |
| 207 _direct_allocated_words = 0; | |
| 208 NOT_PRODUCT( | |
| 209 _numObjectsPromoted = 0; | |
| 210 _numWordsPromoted = 0; | |
| 211 _numObjectsAllocated = 0; | |
| 212 _numWordsAllocated = 0; | |
| 213 ) | |
| 214 | |
| 215 _cmsSpace = new CompactibleFreeListSpace(_bts, MemRegion(bottom, end), | |
| 216 use_adaptive_freelists, | |
| 217 dictionaryChoice); | |
| 218 NOT_PRODUCT(debug_cms_space = _cmsSpace;) | |
| 219 if (_cmsSpace == NULL) { | |
| 220 vm_exit_during_initialization( | |
| 221 "CompactibleFreeListSpace allocation failure"); | |
| 222 } | |
| 223 _cmsSpace->_gen = this; | |
| 224 | |
| 225 _gc_stats = new CMSGCStats(); | |
| 226 | |
| 227 // Verify the assumption that FreeChunk::_prev and OopDesc::_klass | |
| 228 // offsets match. The ability to tell free chunks from objects | |
| 229 // depends on this property. | |
| 230 debug_only( | |
| 231 FreeChunk* junk = NULL; | |
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232 assert(UseCompressedKlassPointers || |
| 187 | 233 junk->prev_addr() == (void*)(oop(junk)->klass_addr()), |
| 0 | 234 "Offset of FreeChunk::_prev within FreeChunk must match" |
| 235 " that of OopDesc::_klass within OopDesc"); | |
| 236 ) | |
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237 if (CollectedHeap::use_parallel_gc_threads()) { |
| 0 | 238 typedef CMSParGCThreadState* CMSParGCThreadStatePtr; |
| 239 _par_gc_thread_states = | |
| 6197 | 240 NEW_C_HEAP_ARRAY(CMSParGCThreadStatePtr, ParallelGCThreads, mtGC); |
| 0 | 241 if (_par_gc_thread_states == NULL) { |
| 242 vm_exit_during_initialization("Could not allocate par gc structs"); | |
| 243 } | |
| 244 for (uint i = 0; i < ParallelGCThreads; i++) { | |
| 245 _par_gc_thread_states[i] = new CMSParGCThreadState(cmsSpace()); | |
| 246 if (_par_gc_thread_states[i] == NULL) { | |
| 247 vm_exit_during_initialization("Could not allocate par gc structs"); | |
| 248 } | |
| 249 } | |
| 250 } else { | |
| 251 _par_gc_thread_states = NULL; | |
| 252 } | |
| 253 _incremental_collection_failed = false; | |
| 254 // The "dilatation_factor" is the expansion that can occur on | |
| 255 // account of the fact that the minimum object size in the CMS | |
| 256 // generation may be larger than that in, say, a contiguous young | |
| 257 // generation. | |
| 258 // Ideally, in the calculation below, we'd compute the dilatation | |
| 259 // factor as: MinChunkSize/(promoting_gen's min object size) | |
| 260 // Since we do not have such a general query interface for the | |
| 261 // promoting generation, we'll instead just use the mimimum | |
| 262 // object size (which today is a header's worth of space); | |
| 263 // note that all arithmetic is in units of HeapWords. | |
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264 assert(MinChunkSize >= CollectedHeap::min_fill_size(), "just checking"); |
| 0 | 265 assert(_dilatation_factor >= 1.0, "from previous assert"); |
| 266 } | |
| 267 | |
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268 |
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269 // The field "_initiating_occupancy" represents the occupancy percentage |
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270 // at which we trigger a new collection cycle. Unless explicitly specified |
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271 // via CMSInitiatingOccupancyFraction (argument "io" below), it |
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272 // is calculated by: |
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273 // |
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274 // Let "f" be MinHeapFreeRatio in |
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275 // |
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276 // _intiating_occupancy = 100-f + |
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277 // f * (CMSTriggerRatio/100) |
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278 // where CMSTriggerRatio is the argument "tr" below. |
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279 // |
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280 // That is, if we assume the heap is at its desired maximum occupancy at the |
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281 // end of a collection, we let CMSTriggerRatio of the (purported) free |
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282 // space be allocated before initiating a new collection cycle. |
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283 // |
| 8035 | 284 void ConcurrentMarkSweepGeneration::init_initiating_occupancy(intx io, uintx tr) { |
| 285 assert(io <= 100 && tr <= 100, "Check the arguments"); | |
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286 if (io >= 0) { |
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287 _initiating_occupancy = (double)io / 100.0; |
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288 } else { |
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289 _initiating_occupancy = ((100 - MinHeapFreeRatio) + |
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290 (double)(tr * MinHeapFreeRatio) / 100.0) |
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291 / 100.0; |
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292 } |
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293 } |
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294 |
| 0 | 295 void ConcurrentMarkSweepGeneration::ref_processor_init() { |
| 296 assert(collector() != NULL, "no collector"); | |
| 297 collector()->ref_processor_init(); | |
| 298 } | |
| 299 | |
| 300 void CMSCollector::ref_processor_init() { | |
| 301 if (_ref_processor == NULL) { | |
| 302 // Allocate and initialize a reference processor | |
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303 _ref_processor = |
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304 new ReferenceProcessor(_span, // span |
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305 (ParallelGCThreads > 1) && ParallelRefProcEnabled, // mt processing |
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306 (int) ParallelGCThreads, // mt processing degree |
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307 _cmsGen->refs_discovery_is_mt(), // mt discovery |
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308 (int) MAX2(ConcGCThreads, ParallelGCThreads), // mt discovery degree |
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309 _cmsGen->refs_discovery_is_atomic(), // discovery is not atomic |
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310 &_is_alive_closure, // closure for liveness info |
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311 false); // next field updates do not need write barrier |
| 0 | 312 // Initialize the _ref_processor field of CMSGen |
| 313 _cmsGen->set_ref_processor(_ref_processor); | |
| 314 | |
| 315 } | |
| 316 } | |
| 317 | |
| 318 CMSAdaptiveSizePolicy* CMSCollector::size_policy() { | |
| 319 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 320 assert(gch->kind() == CollectedHeap::GenCollectedHeap, | |
| 321 "Wrong type of heap"); | |
| 322 CMSAdaptiveSizePolicy* sp = (CMSAdaptiveSizePolicy*) | |
| 323 gch->gen_policy()->size_policy(); | |
| 324 assert(sp->is_gc_cms_adaptive_size_policy(), | |
| 325 "Wrong type of size policy"); | |
| 326 return sp; | |
| 327 } | |
| 328 | |
| 329 CMSGCAdaptivePolicyCounters* CMSCollector::gc_adaptive_policy_counters() { | |
| 330 CMSGCAdaptivePolicyCounters* results = | |
| 331 (CMSGCAdaptivePolicyCounters*) collector_policy()->counters(); | |
| 332 assert( | |
| 333 results->kind() == GCPolicyCounters::CMSGCAdaptivePolicyCountersKind, | |
| 334 "Wrong gc policy counter kind"); | |
| 335 return results; | |
| 336 } | |
| 337 | |
| 338 | |
| 339 void ConcurrentMarkSweepGeneration::initialize_performance_counters() { | |
| 340 | |
| 341 const char* gen_name = "old"; | |
| 342 | |
| 343 // Generation Counters - generation 1, 1 subspace | |
| 344 _gen_counters = new GenerationCounters(gen_name, 1, 1, &_virtual_space); | |
| 345 | |
| 346 _space_counters = new GSpaceCounters(gen_name, 0, | |
| 347 _virtual_space.reserved_size(), | |
| 348 this, _gen_counters); | |
| 349 } | |
| 350 | |
| 351 CMSStats::CMSStats(ConcurrentMarkSweepGeneration* cms_gen, unsigned int alpha): | |
| 352 _cms_gen(cms_gen) | |
| 353 { | |
| 354 assert(alpha <= 100, "bad value"); | |
| 355 _saved_alpha = alpha; | |
| 356 | |
| 357 // Initialize the alphas to the bootstrap value of 100. | |
| 358 _gc0_alpha = _cms_alpha = 100; | |
| 359 | |
| 360 _cms_begin_time.update(); | |
| 361 _cms_end_time.update(); | |
| 362 | |
| 363 _gc0_duration = 0.0; | |
| 364 _gc0_period = 0.0; | |
| 365 _gc0_promoted = 0; | |
| 366 | |
| 367 _cms_duration = 0.0; | |
| 368 _cms_period = 0.0; | |
| 369 _cms_allocated = 0; | |
| 370 | |
| 371 _cms_used_at_gc0_begin = 0; | |
| 372 _cms_used_at_gc0_end = 0; | |
| 373 _allow_duty_cycle_reduction = false; | |
| 374 _valid_bits = 0; | |
| 375 _icms_duty_cycle = CMSIncrementalDutyCycle; | |
| 376 } | |
| 377 | |
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378 double CMSStats::cms_free_adjustment_factor(size_t free) const { |
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379 // TBD: CR 6909490 |
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380 return 1.0; |
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381 } |
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382 |
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383 void CMSStats::adjust_cms_free_adjustment_factor(bool fail, size_t free) { |
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384 } |
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385 |
| 0 | 386 // If promotion failure handling is on use |
| 387 // the padded average size of the promotion for each | |
| 388 // young generation collection. | |
| 389 double CMSStats::time_until_cms_gen_full() const { | |
| 390 size_t cms_free = _cms_gen->cmsSpace()->free(); | |
| 391 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
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392 size_t expected_promotion = MIN2(gch->get_gen(0)->capacity(), |
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393 (size_t) _cms_gen->gc_stats()->avg_promoted()->padded_average()); |
| 0 | 394 if (cms_free > expected_promotion) { |
| 395 // Start a cms collection if there isn't enough space to promote | |
| 396 // for the next minor collection. Use the padded average as | |
| 397 // a safety factor. | |
| 398 cms_free -= expected_promotion; | |
| 399 | |
| 400 // Adjust by the safety factor. | |
| 401 double cms_free_dbl = (double)cms_free; | |
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402 double cms_adjustment = (100.0 - CMSIncrementalSafetyFactor)/100.0; |
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403 // Apply a further correction factor which tries to adjust |
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404 // for recent occurance of concurrent mode failures. |
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405 cms_adjustment = cms_adjustment * cms_free_adjustment_factor(cms_free); |
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406 cms_free_dbl = cms_free_dbl * cms_adjustment; |
| 0 | 407 |
| 408 if (PrintGCDetails && Verbose) { | |
| 409 gclog_or_tty->print_cr("CMSStats::time_until_cms_gen_full: cms_free " | |
| 410 SIZE_FORMAT " expected_promotion " SIZE_FORMAT, | |
| 411 cms_free, expected_promotion); | |
| 412 gclog_or_tty->print_cr(" cms_free_dbl %f cms_consumption_rate %f", | |
| 413 cms_free_dbl, cms_consumption_rate() + 1.0); | |
| 414 } | |
| 415 // Add 1 in case the consumption rate goes to zero. | |
| 416 return cms_free_dbl / (cms_consumption_rate() + 1.0); | |
| 417 } | |
| 418 return 0.0; | |
| 419 } | |
| 420 | |
| 421 // Compare the duration of the cms collection to the | |
| 422 // time remaining before the cms generation is empty. | |
| 423 // Note that the time from the start of the cms collection | |
| 424 // to the start of the cms sweep (less than the total | |
| 425 // duration of the cms collection) can be used. This | |
| 426 // has been tried and some applications experienced | |
| 427 // promotion failures early in execution. This was | |
| 428 // possibly because the averages were not accurate | |
| 429 // enough at the beginning. | |
| 430 double CMSStats::time_until_cms_start() const { | |
| 431 // We add "gc0_period" to the "work" calculation | |
| 432 // below because this query is done (mostly) at the | |
| 433 // end of a scavenge, so we need to conservatively | |
| 434 // account for that much possible delay | |
| 435 // in the query so as to avoid concurrent mode failures | |
| 436 // due to starting the collection just a wee bit too | |
| 437 // late. | |
| 438 double work = cms_duration() + gc0_period(); | |
| 439 double deadline = time_until_cms_gen_full(); | |
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440 // If a concurrent mode failure occurred recently, we want to be |
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441 // more conservative and halve our expected time_until_cms_gen_full() |
| 0 | 442 if (work > deadline) { |
| 443 if (Verbose && PrintGCDetails) { | |
| 444 gclog_or_tty->print( | |
| 445 " CMSCollector: collect because of anticipated promotion " | |
| 446 "before full %3.7f + %3.7f > %3.7f ", cms_duration(), | |
| 447 gc0_period(), time_until_cms_gen_full()); | |
| 448 } | |
| 449 return 0.0; | |
| 450 } | |
| 451 return work - deadline; | |
| 452 } | |
| 453 | |
| 454 // Return a duty cycle based on old_duty_cycle and new_duty_cycle, limiting the | |
| 455 // amount of change to prevent wild oscillation. | |
| 456 unsigned int CMSStats::icms_damped_duty_cycle(unsigned int old_duty_cycle, | |
| 457 unsigned int new_duty_cycle) { | |
| 458 assert(old_duty_cycle <= 100, "bad input value"); | |
| 459 assert(new_duty_cycle <= 100, "bad input value"); | |
| 460 | |
| 461 // Note: use subtraction with caution since it may underflow (values are | |
| 462 // unsigned). Addition is safe since we're in the range 0-100. | |
| 463 unsigned int damped_duty_cycle = new_duty_cycle; | |
| 464 if (new_duty_cycle < old_duty_cycle) { | |
| 465 const unsigned int largest_delta = MAX2(old_duty_cycle / 4, 5U); | |
| 466 if (new_duty_cycle + largest_delta < old_duty_cycle) { | |
| 467 damped_duty_cycle = old_duty_cycle - largest_delta; | |
| 468 } | |
| 469 } else if (new_duty_cycle > old_duty_cycle) { | |
| 470 const unsigned int largest_delta = MAX2(old_duty_cycle / 4, 15U); | |
| 471 if (new_duty_cycle > old_duty_cycle + largest_delta) { | |
| 472 damped_duty_cycle = MIN2(old_duty_cycle + largest_delta, 100U); | |
| 473 } | |
| 474 } | |
| 475 assert(damped_duty_cycle <= 100, "invalid duty cycle computed"); | |
| 476 | |
| 477 if (CMSTraceIncrementalPacing) { | |
| 478 gclog_or_tty->print(" [icms_damped_duty_cycle(%d,%d) = %d] ", | |
| 479 old_duty_cycle, new_duty_cycle, damped_duty_cycle); | |
| 480 } | |
| 481 return damped_duty_cycle; | |
| 482 } | |
| 483 | |
| 484 unsigned int CMSStats::icms_update_duty_cycle_impl() { | |
| 485 assert(CMSIncrementalPacing && valid(), | |
| 486 "should be handled in icms_update_duty_cycle()"); | |
| 487 | |
| 488 double cms_time_so_far = cms_timer().seconds(); | |
| 489 double scaled_duration = cms_duration_per_mb() * _cms_used_at_gc0_end / M; | |
| 490 double scaled_duration_remaining = fabsd(scaled_duration - cms_time_so_far); | |
| 491 | |
| 492 // Avoid division by 0. | |
| 493 double time_until_full = MAX2(time_until_cms_gen_full(), 0.01); | |
| 494 double duty_cycle_dbl = 100.0 * scaled_duration_remaining / time_until_full; | |
| 495 | |
| 496 unsigned int new_duty_cycle = MIN2((unsigned int)duty_cycle_dbl, 100U); | |
| 497 if (new_duty_cycle > _icms_duty_cycle) { | |
| 498 // Avoid very small duty cycles (1 or 2); 0 is allowed. | |
| 499 if (new_duty_cycle > 2) { | |
| 500 _icms_duty_cycle = icms_damped_duty_cycle(_icms_duty_cycle, | |
| 501 new_duty_cycle); | |
| 502 } | |
| 503 } else if (_allow_duty_cycle_reduction) { | |
| 504 // The duty cycle is reduced only once per cms cycle (see record_cms_end()). | |
| 505 new_duty_cycle = icms_damped_duty_cycle(_icms_duty_cycle, new_duty_cycle); | |
| 506 // Respect the minimum duty cycle. | |
| 507 unsigned int min_duty_cycle = (unsigned int)CMSIncrementalDutyCycleMin; | |
| 508 _icms_duty_cycle = MAX2(new_duty_cycle, min_duty_cycle); | |
| 509 } | |
| 510 | |
| 511 if (PrintGCDetails || CMSTraceIncrementalPacing) { | |
| 512 gclog_or_tty->print(" icms_dc=%d ", _icms_duty_cycle); | |
| 513 } | |
| 514 | |
| 515 _allow_duty_cycle_reduction = false; | |
| 516 return _icms_duty_cycle; | |
| 517 } | |
| 518 | |
| 519 #ifndef PRODUCT | |
| 520 void CMSStats::print_on(outputStream *st) const { | |
| 521 st->print(" gc0_alpha=%d,cms_alpha=%d", _gc0_alpha, _cms_alpha); | |
| 522 st->print(",gc0_dur=%g,gc0_per=%g,gc0_promo=" SIZE_FORMAT, | |
| 523 gc0_duration(), gc0_period(), gc0_promoted()); | |
| 524 st->print(",cms_dur=%g,cms_dur_per_mb=%g,cms_per=%g,cms_alloc=" SIZE_FORMAT, | |
| 525 cms_duration(), cms_duration_per_mb(), | |
| 526 cms_period(), cms_allocated()); | |
| 527 st->print(",cms_since_beg=%g,cms_since_end=%g", | |
| 528 cms_time_since_begin(), cms_time_since_end()); | |
| 529 st->print(",cms_used_beg=" SIZE_FORMAT ",cms_used_end=" SIZE_FORMAT, | |
| 530 _cms_used_at_gc0_begin, _cms_used_at_gc0_end); | |
| 531 if (CMSIncrementalMode) { | |
| 532 st->print(",dc=%d", icms_duty_cycle()); | |
| 533 } | |
| 534 | |
| 535 if (valid()) { | |
| 536 st->print(",promo_rate=%g,cms_alloc_rate=%g", | |
| 537 promotion_rate(), cms_allocation_rate()); | |
| 538 st->print(",cms_consumption_rate=%g,time_until_full=%g", | |
| 539 cms_consumption_rate(), time_until_cms_gen_full()); | |
| 540 } | |
| 541 st->print(" "); | |
| 542 } | |
| 543 #endif // #ifndef PRODUCT | |
| 544 | |
| 545 CMSCollector::CollectorState CMSCollector::_collectorState = | |
| 546 CMSCollector::Idling; | |
| 547 bool CMSCollector::_foregroundGCIsActive = false; | |
| 548 bool CMSCollector::_foregroundGCShouldWait = false; | |
| 549 | |
| 550 CMSCollector::CMSCollector(ConcurrentMarkSweepGeneration* cmsGen, | |
| 551 CardTableRS* ct, | |
| 552 ConcurrentMarkSweepPolicy* cp): | |
| 553 _cmsGen(cmsGen), | |
| 554 _ct(ct), | |
| 555 _ref_processor(NULL), // will be set later | |
| 556 _conc_workers(NULL), // may be set later | |
| 557 _abort_preclean(false), | |
| 558 _start_sampling(false), | |
| 559 _between_prologue_and_epilogue(false), | |
| 560 _markBitMap(0, Mutex::leaf + 1, "CMS_markBitMap_lock"), | |
| 561 _modUnionTable((CardTableModRefBS::card_shift - LogHeapWordSize), | |
| 562 -1 /* lock-free */, "No_lock" /* dummy */), | |
| 563 _modUnionClosure(&_modUnionTable), | |
| 564 _modUnionClosurePar(&_modUnionTable), | |
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565 // Adjust my span to cover old (cms) gen |
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566 _span(cmsGen->reserved()), |
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567 // Construct the is_alive_closure with _span & markBitMap |
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568 _is_alive_closure(_span, &_markBitMap), |
| 0 | 569 _restart_addr(NULL), |
| 570 _overflow_list(NULL), | |
| 571 _stats(cmsGen), | |
| 572 _eden_chunk_array(NULL), // may be set in ctor body | |
| 573 _eden_chunk_capacity(0), // -- ditto -- | |
| 574 _eden_chunk_index(0), // -- ditto -- | |
| 575 _survivor_plab_array(NULL), // -- ditto -- | |
| 576 _survivor_chunk_array(NULL), // -- ditto -- | |
| 577 _survivor_chunk_capacity(0), // -- ditto -- | |
| 578 _survivor_chunk_index(0), // -- ditto -- | |
| 579 _ser_pmc_preclean_ovflw(0), | |
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580 _ser_kac_preclean_ovflw(0), |
| 0 | 581 _ser_pmc_remark_ovflw(0), |
| 582 _par_pmc_remark_ovflw(0), | |
| 583 _ser_kac_ovflw(0), | |
| 584 _par_kac_ovflw(0), | |
| 585 #ifndef PRODUCT | |
| 586 _num_par_pushes(0), | |
| 587 #endif | |
| 588 _collection_count_start(0), | |
| 589 _verifying(false), | |
| 590 _icms_start_limit(NULL), | |
| 591 _icms_stop_limit(NULL), | |
| 592 _verification_mark_bm(0, Mutex::leaf + 1, "CMS_verification_mark_bm_lock"), | |
| 593 _completed_initialization(false), | |
| 594 _collector_policy(cp), | |
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595 _should_unload_classes(false), |
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596 _concurrent_cycles_since_last_unload(0), |
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597 _roots_scanning_options(0), |
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598 _inter_sweep_estimate(CMS_SweepWeight, CMS_SweepPadding), |
| 10405 | 599 _intra_sweep_estimate(CMS_SweepWeight, CMS_SweepPadding), |
| 600 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) CMSTracer()), | |
| 601 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), | |
| 602 _cms_start_registered(false) | |
| 0 | 603 { |
| 604 if (ExplicitGCInvokesConcurrentAndUnloadsClasses) { | |
| 605 ExplicitGCInvokesConcurrent = true; | |
| 606 } | |
| 607 // Now expand the span and allocate the collection support structures | |
| 608 // (MUT, marking bit map etc.) to cover both generations subject to | |
| 609 // collection. | |
| 610 | |
| 611 // For use by dirty card to oop closures. | |
| 612 _cmsGen->cmsSpace()->set_collector(this); | |
| 613 | |
| 614 // Allocate MUT and marking bit map | |
| 615 { | |
| 616 MutexLockerEx x(_markBitMap.lock(), Mutex::_no_safepoint_check_flag); | |
| 617 if (!_markBitMap.allocate(_span)) { | |
| 618 warning("Failed to allocate CMS Bit Map"); | |
| 619 return; | |
| 620 } | |
| 621 assert(_markBitMap.covers(_span), "_markBitMap inconsistency?"); | |
| 622 } | |
| 623 { | |
| 624 _modUnionTable.allocate(_span); | |
| 625 assert(_modUnionTable.covers(_span), "_modUnionTable inconsistency?"); | |
| 626 } | |
| 627 | |
| 1284 | 628 if (!_markStack.allocate(MarkStackSize)) { |
| 0 | 629 warning("Failed to allocate CMS Marking Stack"); |
| 630 return; | |
| 631 } | |
| 632 | |
| 633 // Support for multi-threaded concurrent phases | |
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634 if (CMSConcurrentMTEnabled) { |
| 1284 | 635 if (FLAG_IS_DEFAULT(ConcGCThreads)) { |
| 0 | 636 // just for now |
| 1284 | 637 FLAG_SET_DEFAULT(ConcGCThreads, (ParallelGCThreads + 3)/4); |
| 638 } | |
| 639 if (ConcGCThreads > 1) { | |
| 0 | 640 _conc_workers = new YieldingFlexibleWorkGang("Parallel CMS Threads", |
| 1284 | 641 ConcGCThreads, true); |
| 0 | 642 if (_conc_workers == NULL) { |
| 643 warning("GC/CMS: _conc_workers allocation failure: " | |
| 644 "forcing -CMSConcurrentMTEnabled"); | |
| 645 CMSConcurrentMTEnabled = false; | |
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646 } else { |
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647 _conc_workers->initialize_workers(); |
| 0 | 648 } |
| 649 } else { | |
| 650 CMSConcurrentMTEnabled = false; | |
| 651 } | |
| 652 } | |
| 653 if (!CMSConcurrentMTEnabled) { | |
| 1284 | 654 ConcGCThreads = 0; |
| 0 | 655 } else { |
| 656 // Turn off CMSCleanOnEnter optimization temporarily for | |
| 657 // the MT case where it's not fixed yet; see 6178663. | |
| 658 CMSCleanOnEnter = false; | |
| 659 } | |
| 1284 | 660 assert((_conc_workers != NULL) == (ConcGCThreads > 1), |
| 0 | 661 "Inconsistency"); |
| 662 | |
| 663 // Parallel task queues; these are shared for the | |
| 664 // concurrent and stop-world phases of CMS, but | |
| 665 // are not shared with parallel scavenge (ParNew). | |
| 666 { | |
| 667 uint i; | |
| 1284 | 668 uint num_queues = (uint) MAX2(ParallelGCThreads, ConcGCThreads); |
| 0 | 669 |
| 670 if ((CMSParallelRemarkEnabled || CMSConcurrentMTEnabled | |
| 671 || ParallelRefProcEnabled) | |
| 672 && num_queues > 0) { | |
| 673 _task_queues = new OopTaskQueueSet(num_queues); | |
| 674 if (_task_queues == NULL) { | |
| 675 warning("task_queues allocation failure."); | |
| 676 return; | |
| 677 } | |
| 6197 | 678 _hash_seed = NEW_C_HEAP_ARRAY(int, num_queues, mtGC); |
| 0 | 679 if (_hash_seed == NULL) { |
| 680 warning("_hash_seed array allocation failure"); | |
| 681 return; | |
| 682 } | |
| 683 | |
| 1665 | 684 typedef Padded<OopTaskQueue> PaddedOopTaskQueue; |
| 0 | 685 for (i = 0; i < num_queues; i++) { |
| 1665 | 686 PaddedOopTaskQueue *q = new PaddedOopTaskQueue(); |
| 687 if (q == NULL) { | |
| 0 | 688 warning("work_queue allocation failure."); |
| 689 return; | |
| 690 } | |
| 1665 | 691 _task_queues->register_queue(i, q); |
| 0 | 692 } |
| 693 for (i = 0; i < num_queues; i++) { | |
| 694 _task_queues->queue(i)->initialize(); | |
| 695 _hash_seed[i] = 17; // copied from ParNew | |
| 696 } | |
| 697 } | |
| 698 } | |
| 699 | |
|
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700 _cmsGen ->init_initiating_occupancy(CMSInitiatingOccupancyFraction, CMSTriggerRatio); |
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701 |
| 0 | 702 // Clip CMSBootstrapOccupancy between 0 and 100. |
|
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703 _bootstrap_occupancy = ((double)CMSBootstrapOccupancy)/(double)100; |
| 0 | 704 |
| 705 _full_gcs_since_conc_gc = 0; | |
| 706 | |
| 707 // Now tell CMS generations the identity of their collector | |
| 708 ConcurrentMarkSweepGeneration::set_collector(this); | |
| 709 | |
| 710 // Create & start a CMS thread for this CMS collector | |
| 711 _cmsThread = ConcurrentMarkSweepThread::start(this); | |
| 712 assert(cmsThread() != NULL, "CMS Thread should have been created"); | |
| 713 assert(cmsThread()->collector() == this, | |
| 714 "CMS Thread should refer to this gen"); | |
| 715 assert(CGC_lock != NULL, "Where's the CGC_lock?"); | |
| 716 | |
| 717 // Support for parallelizing young gen rescan | |
| 718 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 719 _young_gen = gch->prev_gen(_cmsGen); | |
| 720 if (gch->supports_inline_contig_alloc()) { | |
| 721 _top_addr = gch->top_addr(); | |
| 722 _end_addr = gch->end_addr(); | |
| 723 assert(_young_gen != NULL, "no _young_gen"); | |
| 724 _eden_chunk_index = 0; | |
| 725 _eden_chunk_capacity = (_young_gen->max_capacity()+CMSSamplingGrain)/CMSSamplingGrain; | |
| 6197 | 726 _eden_chunk_array = NEW_C_HEAP_ARRAY(HeapWord*, _eden_chunk_capacity, mtGC); |
| 0 | 727 if (_eden_chunk_array == NULL) { |
| 728 _eden_chunk_capacity = 0; | |
| 729 warning("GC/CMS: _eden_chunk_array allocation failure"); | |
| 730 } | |
| 731 } | |
| 732 assert(_eden_chunk_array != NULL || _eden_chunk_capacity == 0, "Error"); | |
| 733 | |
| 734 // Support for parallelizing survivor space rescan | |
| 735 if (CMSParallelRemarkEnabled && CMSParallelSurvivorRemarkEnabled) { | |
|
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736 const size_t max_plab_samples = |
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737 ((DefNewGeneration*)_young_gen)->max_survivor_size()/MinTLABSize; |
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738 |
| 6197 | 739 _survivor_plab_array = NEW_C_HEAP_ARRAY(ChunkArray, ParallelGCThreads, mtGC); |
| 740 _survivor_chunk_array = NEW_C_HEAP_ARRAY(HeapWord*, 2*max_plab_samples, mtGC); | |
| 741 _cursor = NEW_C_HEAP_ARRAY(size_t, ParallelGCThreads, mtGC); | |
| 0 | 742 if (_survivor_plab_array == NULL || _survivor_chunk_array == NULL |
| 743 || _cursor == NULL) { | |
| 744 warning("Failed to allocate survivor plab/chunk array"); | |
| 745 if (_survivor_plab_array != NULL) { | |
| 6197 | 746 FREE_C_HEAP_ARRAY(ChunkArray, _survivor_plab_array, mtGC); |
| 0 | 747 _survivor_plab_array = NULL; |
| 748 } | |
| 749 if (_survivor_chunk_array != NULL) { | |
| 6197 | 750 FREE_C_HEAP_ARRAY(HeapWord*, _survivor_chunk_array, mtGC); |
| 0 | 751 _survivor_chunk_array = NULL; |
| 752 } | |
| 753 if (_cursor != NULL) { | |
| 6197 | 754 FREE_C_HEAP_ARRAY(size_t, _cursor, mtGC); |
| 0 | 755 _cursor = NULL; |
| 756 } | |
| 757 } else { | |
| 758 _survivor_chunk_capacity = 2*max_plab_samples; | |
| 759 for (uint i = 0; i < ParallelGCThreads; i++) { | |
| 6197 | 760 HeapWord** vec = NEW_C_HEAP_ARRAY(HeapWord*, max_plab_samples, mtGC); |
| 0 | 761 if (vec == NULL) { |
| 762 warning("Failed to allocate survivor plab array"); | |
| 763 for (int j = i; j > 0; j--) { | |
| 6197 | 764 FREE_C_HEAP_ARRAY(HeapWord*, _survivor_plab_array[j-1].array(), mtGC); |
| 0 | 765 } |
| 6197 | 766 FREE_C_HEAP_ARRAY(ChunkArray, _survivor_plab_array, mtGC); |
| 767 FREE_C_HEAP_ARRAY(HeapWord*, _survivor_chunk_array, mtGC); | |
| 0 | 768 _survivor_plab_array = NULL; |
| 769 _survivor_chunk_array = NULL; | |
| 770 _survivor_chunk_capacity = 0; | |
| 771 break; | |
| 772 } else { | |
| 773 ChunkArray* cur = | |
| 774 ::new (&_survivor_plab_array[i]) ChunkArray(vec, | |
| 775 max_plab_samples); | |
| 776 assert(cur->end() == 0, "Should be 0"); | |
| 777 assert(cur->array() == vec, "Should be vec"); | |
| 778 assert(cur->capacity() == max_plab_samples, "Error"); | |
| 779 } | |
| 780 } | |
| 781 } | |
| 782 } | |
| 783 assert( ( _survivor_plab_array != NULL | |
| 784 && _survivor_chunk_array != NULL) | |
| 785 || ( _survivor_chunk_capacity == 0 | |
| 786 && _survivor_chunk_index == 0), | |
| 787 "Error"); | |
| 788 | |
| 789 // Choose what strong roots should be scanned depending on verification options | |
| 790 if (!CMSClassUnloadingEnabled) { | |
| 791 // If class unloading is disabled we want to include all classes into the root set. | |
| 792 add_root_scanning_option(SharedHeap::SO_AllClasses); | |
| 793 } else { | |
| 794 add_root_scanning_option(SharedHeap::SO_SystemClasses); | |
| 795 } | |
| 796 | |
| 797 NOT_PRODUCT(_overflow_counter = CMSMarkStackOverflowInterval;) | |
| 798 _gc_counters = new CollectorCounters("CMS", 1); | |
| 799 _completed_initialization = true; | |
|
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800 _inter_sweep_timer.start(); // start of time |
| 0 | 801 } |
| 802 | |
| 803 const char* ConcurrentMarkSweepGeneration::name() const { | |
| 804 return "concurrent mark-sweep generation"; | |
| 805 } | |
| 806 void ConcurrentMarkSweepGeneration::update_counters() { | |
| 807 if (UsePerfData) { | |
| 808 _space_counters->update_all(); | |
| 809 _gen_counters->update_all(); | |
| 810 } | |
| 811 } | |
| 812 | |
| 813 // this is an optimized version of update_counters(). it takes the | |
| 814 // used value as a parameter rather than computing it. | |
| 815 // | |
| 816 void ConcurrentMarkSweepGeneration::update_counters(size_t used) { | |
| 817 if (UsePerfData) { | |
| 818 _space_counters->update_used(used); | |
| 819 _space_counters->update_capacity(); | |
| 820 _gen_counters->update_all(); | |
| 821 } | |
| 822 } | |
| 823 | |
| 824 void ConcurrentMarkSweepGeneration::print() const { | |
| 825 Generation::print(); | |
| 826 cmsSpace()->print(); | |
| 827 } | |
| 828 | |
| 829 #ifndef PRODUCT | |
| 830 void ConcurrentMarkSweepGeneration::print_statistics() { | |
| 831 cmsSpace()->printFLCensus(0); | |
| 832 } | |
| 833 #endif | |
| 834 | |
| 835 void ConcurrentMarkSweepGeneration::printOccupancy(const char *s) { | |
| 836 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 837 if (PrintGCDetails) { | |
| 838 if (Verbose) { | |
|
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839 gclog_or_tty->print("[%d %s-%s: "SIZE_FORMAT"("SIZE_FORMAT")]", |
| 0 | 840 level(), short_name(), s, used(), capacity()); |
| 841 } else { | |
|
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842 gclog_or_tty->print("[%d %s-%s: "SIZE_FORMAT"K("SIZE_FORMAT"K)]", |
| 0 | 843 level(), short_name(), s, used() / K, capacity() / K); |
| 844 } | |
| 845 } | |
| 846 if (Verbose) { | |
| 847 gclog_or_tty->print(" "SIZE_FORMAT"("SIZE_FORMAT")", | |
| 848 gch->used(), gch->capacity()); | |
| 849 } else { | |
| 850 gclog_or_tty->print(" "SIZE_FORMAT"K("SIZE_FORMAT"K)", | |
| 851 gch->used() / K, gch->capacity() / K); | |
| 852 } | |
| 853 } | |
| 854 | |
| 855 size_t | |
| 856 ConcurrentMarkSweepGeneration::contiguous_available() const { | |
| 857 // dld proposes an improvement in precision here. If the committed | |
| 858 // part of the space ends in a free block we should add that to | |
| 859 // uncommitted size in the calculation below. Will make this | |
| 860 // change later, staying with the approximation below for the | |
| 861 // time being. -- ysr. | |
| 862 return MAX2(_virtual_space.uncommitted_size(), unsafe_max_alloc_nogc()); | |
| 863 } | |
| 864 | |
| 865 size_t | |
| 866 ConcurrentMarkSweepGeneration::unsafe_max_alloc_nogc() const { | |
| 867 return _cmsSpace->max_alloc_in_words() * HeapWordSize; | |
| 868 } | |
| 869 | |
| 870 size_t ConcurrentMarkSweepGeneration::max_available() const { | |
| 871 return free() + _virtual_space.uncommitted_size(); | |
| 872 } | |
| 873 | |
|
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874 bool ConcurrentMarkSweepGeneration::promotion_attempt_is_safe(size_t max_promotion_in_bytes) const { |
|
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875 size_t available = max_available(); |
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876 size_t av_promo = (size_t)gc_stats()->avg_promoted()->padded_average(); |
|
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877 bool res = (available >= av_promo) || (available >= max_promotion_in_bytes); |
|
1994
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878 if (Verbose && PrintGCDetails) { |
|
1888
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879 gclog_or_tty->print_cr( |
|
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880 "CMS: promo attempt is%s safe: available("SIZE_FORMAT") %s av_promo("SIZE_FORMAT")," |
|
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881 "max_promo("SIZE_FORMAT")", |
|
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882 res? "":" not", available, res? ">=":"<", |
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883 av_promo, max_promotion_in_bytes); |
|
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884 } |
|
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|
885 return res; |
| 0 | 886 } |
| 887 | |
|
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888 // At a promotion failure dump information on block layout in heap |
|
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|
889 // (cms old generation). |
|
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|
890 void ConcurrentMarkSweepGeneration::promotion_failure_occurred() { |
|
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6631166: CMS: better heuristics when combatting fragmentation
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|
891 if (CMSDumpAtPromotionFailure) { |
|
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892 cmsSpace()->dump_at_safepoint_with_locks(collector(), gclog_or_tty); |
|
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|
893 } |
|
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|
894 } |
|
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|
895 |
| 0 | 896 CompactibleSpace* |
| 897 ConcurrentMarkSweepGeneration::first_compaction_space() const { | |
| 898 return _cmsSpace; | |
| 899 } | |
| 900 | |
| 901 void ConcurrentMarkSweepGeneration::reset_after_compaction() { | |
| 902 // Clear the promotion information. These pointers can be adjusted | |
| 903 // along with all the other pointers into the heap but | |
| 904 // compaction is expected to be a rare event with | |
| 905 // a heap using cms so don't do it without seeing the need. | |
|
1833
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|
906 if (CollectedHeap::use_parallel_gc_threads()) { |
| 0 | 907 for (uint i = 0; i < ParallelGCThreads; i++) { |
| 908 _par_gc_thread_states[i]->promo.reset(); | |
| 909 } | |
| 910 } | |
| 911 } | |
| 912 | |
| 913 void ConcurrentMarkSweepGeneration::space_iterate(SpaceClosure* blk, bool usedOnly) { | |
| 914 blk->do_space(_cmsSpace); | |
| 915 } | |
| 916 | |
| 917 void ConcurrentMarkSweepGeneration::compute_new_size() { | |
| 918 assert_locked_or_safepoint(Heap_lock); | |
| 919 | |
| 920 // If incremental collection failed, we just want to expand | |
| 921 // to the limit. | |
| 922 if (incremental_collection_failed()) { | |
| 923 clear_incremental_collection_failed(); | |
| 924 grow_to_reserved(); | |
| 925 return; | |
| 926 } | |
| 927 | |
|
10243
a9d568b7df60
8013032: CMS: assert(used() == used_after_gc && used_after_gc <= capacity()) failed: used: 0 used_after_gc: 292080 capacity: 1431699456
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928 // The heap has been compacted but not reset yet. |
|
a9d568b7df60
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929 // Any metric such as free() or used() will be incorrect. |
|
9072
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930 |
|
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|
931 CardGeneration::compute_new_size(); |
|
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932 |
|
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|
933 // Reset again after a possible resizing |
|
10244
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8013184: CMS: Call reset_after_compaction() only if a compaction has been done
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|
934 if (did_compact()) { |
|
06ab37f08701
8013184: CMS: Call reset_after_compaction() only if a compaction has been done
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|
935 cmsSpace()->reset_after_compaction(); |
|
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936 } |
|
9072
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|
937 } |
|
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938 |
|
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939 void ConcurrentMarkSweepGeneration::compute_new_size_free_list() { |
|
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940 assert_locked_or_safepoint(Heap_lock); |
|
8617e38bb4cb
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|
941 |
|
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942 // If incremental collection failed, we just want to expand |
|
8617e38bb4cb
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|
943 // to the limit. |
|
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|
944 if (incremental_collection_failed()) { |
|
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945 clear_incremental_collection_failed(); |
|
8617e38bb4cb
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|
946 grow_to_reserved(); |
|
8617e38bb4cb
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|
947 return; |
|
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|
948 } |
|
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|
949 |
| 0 | 950 double free_percentage = ((double) free()) / capacity(); |
| 951 double desired_free_percentage = (double) MinHeapFreeRatio / 100; | |
| 952 double maximum_free_percentage = (double) MaxHeapFreeRatio / 100; | |
| 953 | |
| 954 // compute expansion delta needed for reaching desired free percentage | |
| 955 if (free_percentage < desired_free_percentage) { | |
| 956 size_t desired_capacity = (size_t)(used() / ((double) 1 - desired_free_percentage)); | |
| 957 assert(desired_capacity >= capacity(), "invalid expansion size"); | |
|
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958 size_t expand_bytes = MAX2(desired_capacity - capacity(), MinHeapDeltaBytes); |
| 0 | 959 if (PrintGCDetails && Verbose) { |
| 960 size_t desired_capacity = (size_t)(used() / ((double) 1 - desired_free_percentage)); | |
| 961 gclog_or_tty->print_cr("\nFrom compute_new_size: "); | |
| 962 gclog_or_tty->print_cr(" Free fraction %f", free_percentage); | |
| 963 gclog_or_tty->print_cr(" Desired free fraction %f", | |
| 964 desired_free_percentage); | |
| 965 gclog_or_tty->print_cr(" Maximum free fraction %f", | |
| 966 maximum_free_percentage); | |
| 967 gclog_or_tty->print_cr(" Capactiy "SIZE_FORMAT, capacity()/1000); | |
| 968 gclog_or_tty->print_cr(" Desired capacity "SIZE_FORMAT, | |
| 969 desired_capacity/1000); | |
| 970 int prev_level = level() - 1; | |
| 971 if (prev_level >= 0) { | |
| 972 size_t prev_size = 0; | |
| 973 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 974 Generation* prev_gen = gch->_gens[prev_level]; | |
| 975 prev_size = prev_gen->capacity(); | |
| 976 gclog_or_tty->print_cr(" Younger gen size "SIZE_FORMAT, | |
| 977 prev_size/1000); | |
| 978 } | |
| 979 gclog_or_tty->print_cr(" unsafe_max_alloc_nogc "SIZE_FORMAT, | |
| 980 unsafe_max_alloc_nogc()/1000); | |
| 981 gclog_or_tty->print_cr(" contiguous available "SIZE_FORMAT, | |
| 982 contiguous_available()/1000); | |
| 983 gclog_or_tty->print_cr(" Expand by "SIZE_FORMAT" (bytes)", | |
| 984 expand_bytes); | |
| 985 } | |
| 986 // safe if expansion fails | |
| 987 expand(expand_bytes, 0, CMSExpansionCause::_satisfy_free_ratio); | |
| 988 if (PrintGCDetails && Verbose) { | |
| 989 gclog_or_tty->print_cr(" Expanded free fraction %f", | |
| 990 ((double) free()) / capacity()); | |
| 991 } | |
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992 } else { |
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993 size_t desired_capacity = (size_t)(used() / ((double) 1 - desired_free_percentage)); |
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994 assert(desired_capacity <= capacity(), "invalid expansion size"); |
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995 size_t shrink_bytes = capacity() - desired_capacity; |
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996 // Don't shrink unless the delta is greater than the minimum shrink we want |
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997 if (shrink_bytes >= MinHeapDeltaBytes) { |
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998 shrink_free_list_by(shrink_bytes); |
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999 } |
| 0 | 1000 } |
| 1001 } | |
| 1002 | |
| 1003 Mutex* ConcurrentMarkSweepGeneration::freelistLock() const { | |
| 1004 return cmsSpace()->freelistLock(); | |
| 1005 } | |
| 1006 | |
| 1007 HeapWord* ConcurrentMarkSweepGeneration::allocate(size_t size, | |
| 1008 bool tlab) { | |
| 1009 CMSSynchronousYieldRequest yr; | |
| 1010 MutexLockerEx x(freelistLock(), | |
| 1011 Mutex::_no_safepoint_check_flag); | |
| 1012 return have_lock_and_allocate(size, tlab); | |
| 1013 } | |
| 1014 | |
| 1015 HeapWord* ConcurrentMarkSweepGeneration::have_lock_and_allocate(size_t size, | |
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1016 bool tlab /* ignored */) { |
| 0 | 1017 assert_lock_strong(freelistLock()); |
| 1018 size_t adjustedSize = CompactibleFreeListSpace::adjustObjectSize(size); | |
| 1019 HeapWord* res = cmsSpace()->allocate(adjustedSize); | |
| 1020 // Allocate the object live (grey) if the background collector has | |
| 1021 // started marking. This is necessary because the marker may | |
| 1022 // have passed this address and consequently this object will | |
| 1023 // not otherwise be greyed and would be incorrectly swept up. | |
| 1024 // Note that if this object contains references, the writing | |
| 1025 // of those references will dirty the card containing this object | |
| 1026 // allowing the object to be blackened (and its references scanned) | |
| 1027 // either during a preclean phase or at the final checkpoint. | |
| 1028 if (res != NULL) { | |
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1029 // We may block here with an uninitialized object with |
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1030 // its mark-bit or P-bits not yet set. Such objects need |
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1031 // to be safely navigable by block_start(). |
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1032 assert(oop(res)->klass_or_null() == NULL, "Object should be uninitialized here."); |
|
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1033 assert(!((FreeChunk*)res)->is_free(), "Error, block will look free but show wrong size"); |
| 0 | 1034 collector()->direct_allocated(res, adjustedSize); |
| 1035 _direct_allocated_words += adjustedSize; | |
| 1036 // allocation counters | |
| 1037 NOT_PRODUCT( | |
| 1038 _numObjectsAllocated++; | |
| 1039 _numWordsAllocated += (int)adjustedSize; | |
| 1040 ) | |
| 1041 } | |
| 1042 return res; | |
| 1043 } | |
| 1044 | |
| 1045 // In the case of direct allocation by mutators in a generation that | |
| 1046 // is being concurrently collected, the object must be allocated | |
| 1047 // live (grey) if the background collector has started marking. | |
| 1048 // This is necessary because the marker may | |
| 1049 // have passed this address and consequently this object will | |
| 1050 // not otherwise be greyed and would be incorrectly swept up. | |
| 1051 // Note that if this object contains references, the writing | |
| 1052 // of those references will dirty the card containing this object | |
| 1053 // allowing the object to be blackened (and its references scanned) | |
| 1054 // either during a preclean phase or at the final checkpoint. | |
| 1055 void CMSCollector::direct_allocated(HeapWord* start, size_t size) { | |
| 1056 assert(_markBitMap.covers(start, size), "Out of bounds"); | |
| 1057 if (_collectorState >= Marking) { | |
| 1058 MutexLockerEx y(_markBitMap.lock(), | |
| 1059 Mutex::_no_safepoint_check_flag); | |
| 1060 // [see comments preceding SweepClosure::do_blk() below for details] | |
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1061 // |
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1062 // Can the P-bits be deleted now? JJJ |
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1063 // |
| 0 | 1064 // 1. need to mark the object as live so it isn't collected |
| 1065 // 2. need to mark the 2nd bit to indicate the object may be uninitialized | |
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1066 // 3. need to mark the end of the object so marking, precleaning or sweeping |
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1067 // can skip over uninitialized or unparsable objects. An allocated |
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1068 // object is considered uninitialized for our purposes as long as |
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1069 // its klass word is NULL. All old gen objects are parsable |
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1070 // as soon as they are initialized.) |
| 0 | 1071 _markBitMap.mark(start); // object is live |
| 1072 _markBitMap.mark(start + 1); // object is potentially uninitialized? | |
| 1073 _markBitMap.mark(start + size - 1); | |
| 1074 // mark end of object | |
| 1075 } | |
| 1076 // check that oop looks uninitialized | |
| 187 | 1077 assert(oop(start)->klass_or_null() == NULL, "_klass should be NULL"); |
| 0 | 1078 } |
| 1079 | |
| 1080 void CMSCollector::promoted(bool par, HeapWord* start, | |
| 1081 bool is_obj_array, size_t obj_size) { | |
| 1082 assert(_markBitMap.covers(start), "Out of bounds"); | |
| 1083 // See comment in direct_allocated() about when objects should | |
| 1084 // be allocated live. | |
| 1085 if (_collectorState >= Marking) { | |
| 1086 // we already hold the marking bit map lock, taken in | |
| 1087 // the prologue | |
| 1088 if (par) { | |
| 1089 _markBitMap.par_mark(start); | |
| 1090 } else { | |
| 1091 _markBitMap.mark(start); | |
| 1092 } | |
| 1093 // We don't need to mark the object as uninitialized (as | |
| 1094 // in direct_allocated above) because this is being done with the | |
| 1095 // world stopped and the object will be initialized by the | |
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1096 // time the marking, precleaning or sweeping get to look at it. |
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1097 // But see the code for copying objects into the CMS generation, |
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1098 // where we need to ensure that concurrent readers of the |
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1099 // block offset table are able to safely navigate a block that |
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1100 // is in flux from being free to being allocated (and in |
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1101 // transition while being copied into) and subsequently |
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1102 // becoming a bona-fide object when the copy/promotion is complete. |
| 0 | 1103 assert(SafepointSynchronize::is_at_safepoint(), |
| 1104 "expect promotion only at safepoints"); | |
| 1105 | |
| 1106 if (_collectorState < Sweeping) { | |
| 1107 // Mark the appropriate cards in the modUnionTable, so that | |
| 1108 // this object gets scanned before the sweep. If this is | |
| 1109 // not done, CMS generation references in the object might | |
| 1110 // not get marked. | |
| 1111 // For the case of arrays, which are otherwise precisely | |
| 1112 // marked, we need to dirty the entire array, not just its head. | |
| 1113 if (is_obj_array) { | |
| 1114 // The [par_]mark_range() method expects mr.end() below to | |
| 1115 // be aligned to the granularity of a bit's representation | |
| 1116 // in the heap. In the case of the MUT below, that's a | |
| 1117 // card size. | |
| 1118 MemRegion mr(start, | |
| 1119 (HeapWord*)round_to((intptr_t)(start + obj_size), | |
| 1120 CardTableModRefBS::card_size /* bytes */)); | |
| 1121 if (par) { | |
| 1122 _modUnionTable.par_mark_range(mr); | |
| 1123 } else { | |
| 1124 _modUnionTable.mark_range(mr); | |
| 1125 } | |
| 1126 } else { // not an obj array; we can just mark the head | |
| 1127 if (par) { | |
| 1128 _modUnionTable.par_mark(start); | |
| 1129 } else { | |
| 1130 _modUnionTable.mark(start); | |
| 1131 } | |
| 1132 } | |
| 1133 } | |
| 1134 } | |
| 1135 } | |
| 1136 | |
| 1137 static inline size_t percent_of_space(Space* space, HeapWord* addr) | |
| 1138 { | |
| 1139 size_t delta = pointer_delta(addr, space->bottom()); | |
| 1140 return (size_t)(delta * 100.0 / (space->capacity() / HeapWordSize)); | |
| 1141 } | |
| 1142 | |
| 1143 void CMSCollector::icms_update_allocation_limits() | |
| 1144 { | |
| 1145 Generation* gen0 = GenCollectedHeap::heap()->get_gen(0); | |
| 1146 EdenSpace* eden = gen0->as_DefNewGeneration()->eden(); | |
| 1147 | |
| 1148 const unsigned int duty_cycle = stats().icms_update_duty_cycle(); | |
| 1149 if (CMSTraceIncrementalPacing) { | |
| 1150 stats().print(); | |
| 1151 } | |
| 1152 | |
| 1153 assert(duty_cycle <= 100, "invalid duty cycle"); | |
| 1154 if (duty_cycle != 0) { | |
| 1155 // The duty_cycle is a percentage between 0 and 100; convert to words and | |
| 1156 // then compute the offset from the endpoints of the space. | |
| 1157 size_t free_words = eden->free() / HeapWordSize; | |
| 1158 double free_words_dbl = (double)free_words; | |
| 1159 size_t duty_cycle_words = (size_t)(free_words_dbl * duty_cycle / 100.0); | |
| 1160 size_t offset_words = (free_words - duty_cycle_words) / 2; | |
| 1161 | |
| 1162 _icms_start_limit = eden->top() + offset_words; | |
| 1163 _icms_stop_limit = eden->end() - offset_words; | |
| 1164 | |
| 1165 // The limits may be adjusted (shifted to the right) by | |
| 1166 // CMSIncrementalOffset, to allow the application more mutator time after a | |
| 1167 // young gen gc (when all mutators were stopped) and before CMS starts and | |
| 1168 // takes away one or more cpus. | |
| 1169 if (CMSIncrementalOffset != 0) { | |
| 1170 double adjustment_dbl = free_words_dbl * CMSIncrementalOffset / 100.0; | |
| 1171 size_t adjustment = (size_t)adjustment_dbl; | |
| 1172 HeapWord* tmp_stop = _icms_stop_limit + adjustment; | |
| 1173 if (tmp_stop > _icms_stop_limit && tmp_stop < eden->end()) { | |
| 1174 _icms_start_limit += adjustment; | |
| 1175 _icms_stop_limit = tmp_stop; | |
| 1176 } | |
| 1177 } | |
| 1178 } | |
| 1179 if (duty_cycle == 0 || (_icms_start_limit == _icms_stop_limit)) { | |
| 1180 _icms_start_limit = _icms_stop_limit = eden->end(); | |
| 1181 } | |
| 1182 | |
| 1183 // Install the new start limit. | |
| 1184 eden->set_soft_end(_icms_start_limit); | |
| 1185 | |
| 1186 if (CMSTraceIncrementalMode) { | |
| 1187 gclog_or_tty->print(" icms alloc limits: " | |
| 1188 PTR_FORMAT "," PTR_FORMAT | |
| 1189 " (" SIZE_FORMAT "%%," SIZE_FORMAT "%%) ", | |
| 1190 _icms_start_limit, _icms_stop_limit, | |
| 1191 percent_of_space(eden, _icms_start_limit), | |
| 1192 percent_of_space(eden, _icms_stop_limit)); | |
| 1193 if (Verbose) { | |
| 1194 gclog_or_tty->print("eden: "); | |
| 1195 eden->print_on(gclog_or_tty); | |
| 1196 } | |
| 1197 } | |
| 1198 } | |
| 1199 | |
| 1200 // Any changes here should try to maintain the invariant | |
| 1201 // that if this method is called with _icms_start_limit | |
| 1202 // and _icms_stop_limit both NULL, then it should return NULL | |
| 1203 // and not notify the icms thread. | |
| 1204 HeapWord* | |
| 1205 CMSCollector::allocation_limit_reached(Space* space, HeapWord* top, | |
| 1206 size_t word_size) | |
| 1207 { | |
| 1208 // A start_limit equal to end() means the duty cycle is 0, so treat that as a | |
| 1209 // nop. | |
| 1210 if (CMSIncrementalMode && _icms_start_limit != space->end()) { | |
| 1211 if (top <= _icms_start_limit) { | |
| 1212 if (CMSTraceIncrementalMode) { | |
| 1213 space->print_on(gclog_or_tty); | |
| 1214 gclog_or_tty->stamp(); | |
| 1215 gclog_or_tty->print_cr(" start limit top=" PTR_FORMAT | |
| 1216 ", new limit=" PTR_FORMAT | |
| 1217 " (" SIZE_FORMAT "%%)", | |
| 1218 top, _icms_stop_limit, | |
| 1219 percent_of_space(space, _icms_stop_limit)); | |
| 1220 } | |
| 1221 ConcurrentMarkSweepThread::start_icms(); | |
| 1222 assert(top < _icms_stop_limit, "Tautology"); | |
| 1223 if (word_size < pointer_delta(_icms_stop_limit, top)) { | |
| 1224 return _icms_stop_limit; | |
| 1225 } | |
| 1226 | |
| 1227 // The allocation will cross both the _start and _stop limits, so do the | |
| 1228 // stop notification also and return end(). | |
| 1229 if (CMSTraceIncrementalMode) { | |
| 1230 space->print_on(gclog_or_tty); | |
| 1231 gclog_or_tty->stamp(); | |
| 1232 gclog_or_tty->print_cr(" +stop limit top=" PTR_FORMAT | |
| 1233 ", new limit=" PTR_FORMAT | |
| 1234 " (" SIZE_FORMAT "%%)", | |
| 1235 top, space->end(), | |
| 1236 percent_of_space(space, space->end())); | |
| 1237 } | |
| 1238 ConcurrentMarkSweepThread::stop_icms(); | |
| 1239 return space->end(); | |
| 1240 } | |
| 1241 | |
| 1242 if (top <= _icms_stop_limit) { | |
| 1243 if (CMSTraceIncrementalMode) { | |
| 1244 space->print_on(gclog_or_tty); | |
| 1245 gclog_or_tty->stamp(); | |
| 1246 gclog_or_tty->print_cr(" stop limit top=" PTR_FORMAT | |
| 1247 ", new limit=" PTR_FORMAT | |
| 1248 " (" SIZE_FORMAT "%%)", | |
| 1249 top, space->end(), | |
| 1250 percent_of_space(space, space->end())); | |
| 1251 } | |
| 1252 ConcurrentMarkSweepThread::stop_icms(); | |
| 1253 return space->end(); | |
| 1254 } | |
| 1255 | |
| 1256 if (CMSTraceIncrementalMode) { | |
| 1257 space->print_on(gclog_or_tty); | |
| 1258 gclog_or_tty->stamp(); | |
| 1259 gclog_or_tty->print_cr(" end limit top=" PTR_FORMAT | |
| 1260 ", new limit=" PTR_FORMAT, | |
| 1261 top, NULL); | |
| 1262 } | |
| 1263 } | |
| 1264 | |
| 1265 return NULL; | |
| 1266 } | |
| 1267 | |
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1268 oop ConcurrentMarkSweepGeneration::promote(oop obj, size_t obj_size) { |
| 0 | 1269 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in"); |
| 1270 // allocate, copy and if necessary update promoinfo -- | |
| 1271 // delegate to underlying space. | |
| 1272 assert_lock_strong(freelistLock()); | |
| 1273 | |
| 1274 #ifndef PRODUCT | |
| 1275 if (Universe::heap()->promotion_should_fail()) { | |
| 1276 return NULL; | |
| 1277 } | |
| 1278 #endif // #ifndef PRODUCT | |
| 1279 | |
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1280 oop res = _cmsSpace->promote(obj, obj_size); |
| 0 | 1281 if (res == NULL) { |
| 1282 // expand and retry | |
| 1283 size_t s = _cmsSpace->expansionSpaceRequired(obj_size); // HeapWords | |
| 1284 expand(s*HeapWordSize, MinHeapDeltaBytes, | |
| 1285 CMSExpansionCause::_satisfy_promotion); | |
| 1286 // Since there's currently no next generation, we don't try to promote | |
| 1287 // into a more senior generation. | |
| 1288 assert(next_gen() == NULL, "assumption, based upon which no attempt " | |
| 1289 "is made to pass on a possibly failing " | |
| 1290 "promotion to next generation"); | |
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1291 res = _cmsSpace->promote(obj, obj_size); |
| 0 | 1292 } |
| 1293 if (res != NULL) { | |
| 1294 // See comment in allocate() about when objects should | |
| 1295 // be allocated live. | |
| 1296 assert(obj->is_oop(), "Will dereference klass pointer below"); | |
| 1297 collector()->promoted(false, // Not parallel | |
| 1298 (HeapWord*)res, obj->is_objArray(), obj_size); | |
| 1299 // promotion counters | |
| 1300 NOT_PRODUCT( | |
| 1301 _numObjectsPromoted++; | |
| 1302 _numWordsPromoted += | |
| 1303 (int)(CompactibleFreeListSpace::adjustObjectSize(obj->size())); | |
| 1304 ) | |
| 1305 } | |
| 1306 return res; | |
| 1307 } | |
| 1308 | |
| 1309 | |
| 1310 HeapWord* | |
| 1311 ConcurrentMarkSweepGeneration::allocation_limit_reached(Space* space, | |
| 1312 HeapWord* top, | |
| 1313 size_t word_sz) | |
| 1314 { | |
| 1315 return collector()->allocation_limit_reached(space, top, word_sz); | |
| 1316 } | |
| 1317 | |
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1318 // IMPORTANT: Notes on object size recognition in CMS. |
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1319 // --------------------------------------------------- |
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1320 // A block of storage in the CMS generation is always in |
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1321 // one of three states. A free block (FREE), an allocated |
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1322 // object (OBJECT) whose size() method reports the correct size, |
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1323 // and an intermediate state (TRANSIENT) in which its size cannot |
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1324 // be accurately determined. |
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1325 // STATE IDENTIFICATION: (32 bit and 64 bit w/o COOPS) |
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1326 // ----------------------------------------------------- |
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1327 // FREE: klass_word & 1 == 1; mark_word holds block size |
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1328 // |
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1329 // OBJECT: klass_word installed; klass_word != 0 && klass_word & 1 == 0; |
|
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1330 // obj->size() computes correct size |
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1331 // |
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1332 // TRANSIENT: klass_word == 0; size is indeterminate until we become an OBJECT |
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1333 // |
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1334 // STATE IDENTIFICATION: (64 bit+COOPS) |
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1335 // ------------------------------------ |
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1336 // FREE: mark_word & CMS_FREE_BIT == 1; mark_word & ~CMS_FREE_BIT gives block_size |
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1337 // |
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1338 // OBJECT: klass_word installed; klass_word != 0; |
|
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1339 // obj->size() computes correct size |
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1340 // |
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1341 // TRANSIENT: klass_word == 0; size is indeterminate until we become an OBJECT |
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1342 // |
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1343 // |
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1344 // STATE TRANSITION DIAGRAM |
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1345 // |
|
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1346 // mut / parnew mut / parnew |
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1347 // FREE --------------------> TRANSIENT ---------------------> OBJECT --| |
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1348 // ^ | |
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1349 // |------------------------ DEAD <------------------------------------| |
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1350 // sweep mut |
|
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1351 // |
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1352 // While a block is in TRANSIENT state its size cannot be determined |
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1353 // so readers will either need to come back later or stall until |
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1354 // the size can be determined. Note that for the case of direct |
|
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1355 // allocation, P-bits, when available, may be used to determine the |
|
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1356 // size of an object that may not yet have been initialized. |
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1357 |
| 0 | 1358 // Things to support parallel young-gen collection. |
| 1359 oop | |
| 1360 ConcurrentMarkSweepGeneration::par_promote(int thread_num, | |
| 1361 oop old, markOop m, | |
| 1362 size_t word_sz) { | |
| 1363 #ifndef PRODUCT | |
| 1364 if (Universe::heap()->promotion_should_fail()) { | |
| 1365 return NULL; | |
| 1366 } | |
| 1367 #endif // #ifndef PRODUCT | |
| 1368 | |
| 1369 CMSParGCThreadState* ps = _par_gc_thread_states[thread_num]; | |
| 1370 PromotionInfo* promoInfo = &ps->promo; | |
| 1371 // if we are tracking promotions, then first ensure space for | |
| 1372 // promotion (including spooling space for saving header if necessary). | |
| 1373 // then allocate and copy, then track promoted info if needed. | |
| 1374 // When tracking (see PromotionInfo::track()), the mark word may | |
| 1375 // be displaced and in this case restoration of the mark word | |
| 1376 // occurs in the (oop_since_save_marks_)iterate phase. | |
| 1377 if (promoInfo->tracking() && !promoInfo->ensure_spooling_space()) { | |
| 1378 // Out of space for allocating spooling buffers; | |
| 1379 // try expanding and allocating spooling buffers. | |
| 1380 if (!expand_and_ensure_spooling_space(promoInfo)) { | |
| 1381 return NULL; | |
| 1382 } | |
| 1383 } | |
| 1384 assert(promoInfo->has_spooling_space(), "Control point invariant"); | |
|
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1385 const size_t alloc_sz = CompactibleFreeListSpace::adjustObjectSize(word_sz); |
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1386 HeapWord* obj_ptr = ps->lab.alloc(alloc_sz); |
| 0 | 1387 if (obj_ptr == NULL) { |
|
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1388 obj_ptr = expand_and_par_lab_allocate(ps, alloc_sz); |
| 0 | 1389 if (obj_ptr == NULL) { |
| 1390 return NULL; | |
| 1391 } | |
| 1392 } | |
| 1393 oop obj = oop(obj_ptr); | |
|
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1394 OrderAccess::storestore(); |
| 187 | 1395 assert(obj->klass_or_null() == NULL, "Object should be uninitialized here."); |
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1396 assert(!((FreeChunk*)obj_ptr)->is_free(), "Error, block will look free but show wrong size"); |
|
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1397 // IMPORTANT: See note on object initialization for CMS above. |
| 0 | 1398 // Otherwise, copy the object. Here we must be careful to insert the |
| 1399 // klass pointer last, since this marks the block as an allocated object. | |
| 187 | 1400 // Except with compressed oops it's the mark word. |
| 0 | 1401 HeapWord* old_ptr = (HeapWord*)old; |
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1402 // Restore the mark word copied above. |
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1403 obj->set_mark(m); |
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1404 assert(obj->klass_or_null() == NULL, "Object should be uninitialized here."); |
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1405 assert(!((FreeChunk*)obj_ptr)->is_free(), "Error, block will look free but show wrong size"); |
|
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1406 OrderAccess::storestore(); |
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1407 |
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1408 if (UseCompressedKlassPointers) { |
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1409 // Copy gap missed by (aligned) header size calculation below |
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1410 obj->set_klass_gap(old->klass_gap()); |
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1411 } |
| 0 | 1412 if (word_sz > (size_t)oopDesc::header_size()) { |
| 1413 Copy::aligned_disjoint_words(old_ptr + oopDesc::header_size(), | |
| 1414 obj_ptr + oopDesc::header_size(), | |
| 1415 word_sz - oopDesc::header_size()); | |
| 1416 } | |
| 187 | 1417 |
| 0 | 1418 // Now we can track the promoted object, if necessary. We take care |
| 1521 | 1419 // to delay the transition from uninitialized to full object |
| 0 | 1420 // (i.e., insertion of klass pointer) until after, so that it |
| 1421 // atomically becomes a promoted object. | |
| 1422 if (promoInfo->tracking()) { | |
| 1423 promoInfo->track((PromotedObject*)obj, old->klass()); | |
| 1424 } | |
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1425 assert(obj->klass_or_null() == NULL, "Object should be uninitialized here."); |
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1426 assert(!((FreeChunk*)obj_ptr)->is_free(), "Error, block will look free but show wrong size"); |
|
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1427 assert(old->is_oop(), "Will use and dereference old klass ptr below"); |
| 187 | 1428 |
| 1429 // Finally, install the klass pointer (this should be volatile). | |
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1430 OrderAccess::storestore(); |
| 0 | 1431 obj->set_klass(old->klass()); |
|
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1432 // We should now be able to calculate the right size for this object |
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1433 assert(obj->is_oop() && obj->size() == (int)word_sz, "Error, incorrect size computed for promoted object"); |
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1434 |
| 0 | 1435 collector()->promoted(true, // parallel |
| 1436 obj_ptr, old->is_objArray(), word_sz); | |
| 1437 | |
| 1438 NOT_PRODUCT( | |
|
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1439 Atomic::inc_ptr(&_numObjectsPromoted); |
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1440 Atomic::add_ptr(alloc_sz, &_numWordsPromoted); |
| 0 | 1441 ) |
| 1442 | |
| 1443 return obj; | |
| 1444 } | |
| 1445 | |
| 1446 void | |
| 1447 ConcurrentMarkSweepGeneration:: | |
| 1448 par_promote_alloc_undo(int thread_num, | |
| 1449 HeapWord* obj, size_t word_sz) { | |
| 1450 // CMS does not support promotion undo. | |
| 1451 ShouldNotReachHere(); | |
| 1452 } | |
| 1453 | |
| 1454 void | |
| 1455 ConcurrentMarkSweepGeneration:: | |
| 1456 par_promote_alloc_done(int thread_num) { | |
| 1457 CMSParGCThreadState* ps = _par_gc_thread_states[thread_num]; | |
|
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1458 ps->lab.retire(thread_num); |
| 0 | 1459 } |
| 1460 | |
| 1461 void | |
| 1462 ConcurrentMarkSweepGeneration:: | |
| 1463 par_oop_since_save_marks_iterate_done(int thread_num) { | |
| 1464 CMSParGCThreadState* ps = _par_gc_thread_states[thread_num]; | |
| 1465 ParScanWithoutBarrierClosure* dummy_cl = NULL; | |
| 1466 ps->promo.promoted_oops_iterate_nv(dummy_cl); | |
| 1467 } | |
| 1468 | |
| 1469 bool ConcurrentMarkSweepGeneration::should_collect(bool full, | |
| 1470 size_t size, | |
| 1471 bool tlab) | |
| 1472 { | |
| 1473 // We allow a STW collection only if a full | |
| 1474 // collection was requested. | |
| 1475 return full || should_allocate(size, tlab); // FIX ME !!! | |
| 1476 // This and promotion failure handling are connected at the | |
| 1477 // hip and should be fixed by untying them. | |
| 1478 } | |
| 1479 | |
| 1480 bool CMSCollector::shouldConcurrentCollect() { | |
| 1481 if (_full_gc_requested) { | |
| 1482 if (Verbose && PrintGCDetails) { | |
| 1483 gclog_or_tty->print_cr("CMSCollector: collect because of explicit " | |
|
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1484 " gc request (or gc_locker)"); |
| 0 | 1485 } |
| 1486 return true; | |
| 1487 } | |
| 1488 | |
| 1489 // For debugging purposes, change the type of collection. | |
| 1490 // If the rotation is not on the concurrent collection | |
| 1491 // type, don't start a concurrent collection. | |
| 1492 NOT_PRODUCT( | |
| 1493 if (RotateCMSCollectionTypes && | |
| 1494 (_cmsGen->debug_collection_type() != | |
| 1495 ConcurrentMarkSweepGeneration::Concurrent_collection_type)) { | |
| 1496 assert(_cmsGen->debug_collection_type() != | |
| 1497 ConcurrentMarkSweepGeneration::Unknown_collection_type, | |
| 1498 "Bad cms collection type"); | |
| 1499 return false; | |
| 1500 } | |
| 1501 ) | |
| 1502 | |
| 1503 FreelistLocker x(this); | |
| 1504 // ------------------------------------------------------------------ | |
| 1505 // Print out lots of information which affects the initiation of | |
| 1506 // a collection. | |
| 1507 if (PrintCMSInitiationStatistics && stats().valid()) { | |
| 1508 gclog_or_tty->print("CMSCollector shouldConcurrentCollect: "); | |
| 1509 gclog_or_tty->stamp(); | |
| 1510 gclog_or_tty->print_cr(""); | |
| 1511 stats().print_on(gclog_or_tty); | |
| 1512 gclog_or_tty->print_cr("time_until_cms_gen_full %3.7f", | |
| 1513 stats().time_until_cms_gen_full()); | |
| 1514 gclog_or_tty->print_cr("free="SIZE_FORMAT, _cmsGen->free()); | |
| 1515 gclog_or_tty->print_cr("contiguous_available="SIZE_FORMAT, | |
| 1516 _cmsGen->contiguous_available()); | |
| 1517 gclog_or_tty->print_cr("promotion_rate=%g", stats().promotion_rate()); | |
| 1518 gclog_or_tty->print_cr("cms_allocation_rate=%g", stats().cms_allocation_rate()); | |
| 1519 gclog_or_tty->print_cr("occupancy=%3.7f", _cmsGen->occupancy()); | |
|
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1520 gclog_or_tty->print_cr("initiatingOccupancy=%3.7f", _cmsGen->initiating_occupancy()); |
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1521 gclog_or_tty->print_cr("metadata initialized %d", |
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1522 MetaspaceGC::should_concurrent_collect()); |
| 0 | 1523 } |
| 1524 // ------------------------------------------------------------------ | |
| 1525 | |
| 1526 // If the estimated time to complete a cms collection (cms_duration()) | |
| 1527 // is less than the estimated time remaining until the cms generation | |
| 1528 // is full, start a collection. | |
| 1529 if (!UseCMSInitiatingOccupancyOnly) { | |
| 1530 if (stats().valid()) { | |
| 1531 if (stats().time_until_cms_start() == 0.0) { | |
| 1532 return true; | |
| 1533 } | |
| 1534 } else { | |
| 1535 // We want to conservatively collect somewhat early in order | |
| 1536 // to try and "bootstrap" our CMS/promotion statistics; | |
| 1537 // this branch will not fire after the first successful CMS | |
| 1538 // collection because the stats should then be valid. | |
| 1539 if (_cmsGen->occupancy() >= _bootstrap_occupancy) { | |
| 1540 if (Verbose && PrintGCDetails) { | |
| 1541 gclog_or_tty->print_cr( | |
| 1542 " CMSCollector: collect for bootstrapping statistics:" | |
| 1543 " occupancy = %f, boot occupancy = %f", _cmsGen->occupancy(), | |
| 1544 _bootstrap_occupancy); | |
| 1545 } | |
| 1546 return true; | |
| 1547 } | |
| 1548 } | |
| 1549 } | |
| 1550 | |
|
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1551 // Otherwise, we start a collection cycle if |
| 0 | 1552 // old gen want a collection cycle started. Each may use |
| 1553 // an appropriate criterion for making this decision. | |
| 1554 // XXX We need to make sure that the gen expansion | |
|
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1555 // criterion dovetails well with this. XXX NEED TO FIX THIS |
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1556 if (_cmsGen->should_concurrent_collect()) { |
| 0 | 1557 if (Verbose && PrintGCDetails) { |
| 1558 gclog_or_tty->print_cr("CMS old gen initiated"); | |
| 1559 } | |
| 1560 return true; | |
| 1561 } | |
| 1562 | |
|
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1563 // We start a collection if we believe an incremental collection may fail; |
|
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1564 // this is not likely to be productive in practice because it's probably too |
|
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1565 // late anyway. |
|
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1566 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
|
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1567 assert(gch->collector_policy()->is_two_generation_policy(), |
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1568 "You may want to check the correctness of the following"); |
|
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1569 if (gch->incremental_collection_will_fail(true /* consult_young */)) { |
|
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1570 if (Verbose && PrintGCDetails) { |
|
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1571 gclog_or_tty->print("CMSCollector: collect because incremental collection will fail "); |
| 0 | 1572 } |
| 1573 return true; | |
| 1574 } | |
| 1575 | |
|
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1576 if (MetaspaceGC::should_concurrent_collect()) { |
|
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1577 if (Verbose && PrintGCDetails) { |
|
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1578 gclog_or_tty->print("CMSCollector: collect for metadata allocation "); |
|
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1579 } |
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1580 return true; |
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1581 } |
|
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1582 |
| 0 | 1583 return false; |
| 1584 } | |
| 1585 | |
|
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1586 void CMSCollector::set_did_compact(bool v) { _cmsGen->set_did_compact(v); } |
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1587 |
| 0 | 1588 // Clear _expansion_cause fields of constituent generations |
| 1589 void CMSCollector::clear_expansion_cause() { | |
| 1590 _cmsGen->clear_expansion_cause(); | |
| 1591 } | |
| 1592 | |
|
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1593 // We should be conservative in starting a collection cycle. To |
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1594 // start too eagerly runs the risk of collecting too often in the |
|
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1595 // extreme. To collect too rarely falls back on full collections, |
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1596 // which works, even if not optimum in terms of concurrent work. |
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1597 // As a work around for too eagerly collecting, use the flag |
|
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1598 // UseCMSInitiatingOccupancyOnly. This also has the advantage of |
|
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1599 // giving the user an easily understandable way of controlling the |
|
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1600 // collections. |
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1601 // We want to start a new collection cycle if any of the following |
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1602 // conditions hold: |
|
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1603 // . our current occupancy exceeds the configured initiating occupancy |
|
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1604 // for this generation, or |
|
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1605 // . we recently needed to expand this space and have not, since that |
|
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1606 // expansion, done a collection of this generation, or |
|
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1607 // . the underlying space believes that it may be a good idea to initiate |
|
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1608 // a concurrent collection (this may be based on criteria such as the |
|
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1609 // following: the space uses linear allocation and linear allocation is |
|
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1610 // going to fail, or there is believed to be excessive fragmentation in |
|
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1611 // the generation, etc... or ... |
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1612 // [.(currently done by CMSCollector::shouldConcurrentCollect() only for |
|
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1613 // the case of the old generation; see CR 6543076): |
|
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1614 // we may be approaching a point at which allocation requests may fail because |
|
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1615 // we will be out of sufficient free space given allocation rate estimates.] |
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1616 bool ConcurrentMarkSweepGeneration::should_concurrent_collect() const { |
|
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1617 |
| 0 | 1618 assert_lock_strong(freelistLock()); |
|
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1619 if (occupancy() > initiating_occupancy()) { |
| 0 | 1620 if (PrintGCDetails && Verbose) { |
| 1621 gclog_or_tty->print(" %s: collect because of occupancy %f / %f ", | |
|
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1622 short_name(), occupancy(), initiating_occupancy()); |
| 0 | 1623 } |
| 1624 return true; | |
| 1625 } | |
| 1626 if (UseCMSInitiatingOccupancyOnly) { | |
| 1627 return false; | |
| 1628 } | |
| 1629 if (expansion_cause() == CMSExpansionCause::_satisfy_allocation) { | |
| 1630 if (PrintGCDetails && Verbose) { | |
| 1631 gclog_or_tty->print(" %s: collect because expanded for allocation ", | |
| 1632 short_name()); | |
| 1633 } | |
| 1634 return true; | |
| 1635 } | |
|
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1636 if (_cmsSpace->should_concurrent_collect()) { |
| 0 | 1637 if (PrintGCDetails && Verbose) { |
|
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1638 gclog_or_tty->print(" %s: collect because cmsSpace says so ", |
| 0 | 1639 short_name()); |
| 1640 } | |
| 1641 return true; | |
| 1642 } | |
| 1643 return false; | |
| 1644 } | |
| 1645 | |
| 1646 void ConcurrentMarkSweepGeneration::collect(bool full, | |
| 1647 bool clear_all_soft_refs, | |
| 1648 size_t size, | |
| 1649 bool tlab) | |
| 1650 { | |
| 1651 collector()->collect(full, clear_all_soft_refs, size, tlab); | |
| 1652 } | |
| 1653 | |
| 1654 void CMSCollector::collect(bool full, | |
| 1655 bool clear_all_soft_refs, | |
| 1656 size_t size, | |
| 1657 bool tlab) | |
| 1658 { | |
| 1659 if (!UseCMSCollectionPassing && _collectorState > Idling) { | |
| 1660 // For debugging purposes skip the collection if the state | |
| 1661 // is not currently idle | |
| 1662 if (TraceCMSState) { | |
| 1663 gclog_or_tty->print_cr("Thread " INTPTR_FORMAT " skipped full:%d CMS state %d", | |
| 1664 Thread::current(), full, _collectorState); | |
| 1665 } | |
| 1666 return; | |
| 1667 } | |
| 1668 | |
| 1669 // The following "if" branch is present for defensive reasons. | |
| 1670 // In the current uses of this interface, it can be replaced with: | |
| 1671 // assert(!GC_locker.is_active(), "Can't be called otherwise"); | |
| 1672 // But I am not placing that assert here to allow future | |
| 1673 // generality in invoking this interface. | |
| 1674 if (GC_locker::is_active()) { | |
| 1675 // A consistency test for GC_locker | |
| 1676 assert(GC_locker::needs_gc(), "Should have been set already"); | |
| 1677 // Skip this foreground collection, instead | |
| 1678 // expanding the heap if necessary. | |
| 1679 // Need the free list locks for the call to free() in compute_new_size() | |
| 1680 compute_new_size(); | |
| 1681 return; | |
| 1682 } | |
| 1683 acquire_control_and_collect(full, clear_all_soft_refs); | |
| 1684 _full_gcs_since_conc_gc++; | |
| 1685 } | |
| 1686 | |
| 10405 | 1687 void CMSCollector::request_full_gc(unsigned int full_gc_count, GCCause::Cause cause) { |
| 0 | 1688 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
| 1689 unsigned int gc_count = gch->total_full_collections(); | |
| 1690 if (gc_count == full_gc_count) { | |
| 1691 MutexLockerEx y(CGC_lock, Mutex::_no_safepoint_check_flag); | |
| 1692 _full_gc_requested = true; | |
| 10405 | 1693 _full_gc_cause = cause; |
| 0 | 1694 CGC_lock->notify(); // nudge CMS thread |
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1695 } else { |
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1696 assert(gc_count > full_gc_count, "Error: causal loop"); |
| 0 | 1697 } |
| 1698 } | |
| 1699 | |
| 10405 | 1700 bool CMSCollector::is_external_interruption() { |
| 1701 GCCause::Cause cause = GenCollectedHeap::heap()->gc_cause(); | |
| 1702 return GCCause::is_user_requested_gc(cause) || | |
| 1703 GCCause::is_serviceability_requested_gc(cause); | |
| 1704 } | |
| 1705 | |
| 1706 void CMSCollector::report_concurrent_mode_interruption() { | |
| 1707 if (is_external_interruption()) { | |
| 1708 if (PrintGCDetails) { | |
| 1709 gclog_or_tty->print(" (concurrent mode interrupted)"); | |
| 1710 } | |
| 1711 } else { | |
| 1712 if (PrintGCDetails) { | |
| 1713 gclog_or_tty->print(" (concurrent mode failure)"); | |
| 1714 } | |
| 1715 _gc_tracer_cm->report_concurrent_mode_failure(); | |
| 1716 } | |
| 1717 } | |
| 1718 | |
| 0 | 1719 |
| 1720 // The foreground and background collectors need to coordinate in order | |
| 1721 // to make sure that they do not mutually interfere with CMS collections. | |
| 1722 // When a background collection is active, | |
| 1723 // the foreground collector may need to take over (preempt) and | |
| 1724 // synchronously complete an ongoing collection. Depending on the | |
| 1725 // frequency of the background collections and the heap usage | |
| 1726 // of the application, this preemption can be seldom or frequent. | |
| 1727 // There are only certain | |
| 1728 // points in the background collection that the "collection-baton" | |
| 1729 // can be passed to the foreground collector. | |
| 1730 // | |
| 1731 // The foreground collector will wait for the baton before | |
| 1732 // starting any part of the collection. The foreground collector | |
| 1733 // will only wait at one location. | |
| 1734 // | |
| 1735 // The background collector will yield the baton before starting a new | |
| 1736 // phase of the collection (e.g., before initial marking, marking from roots, | |
| 1737 // precleaning, final re-mark, sweep etc.) This is normally done at the head | |
| 1738 // of the loop which switches the phases. The background collector does some | |
| 1739 // of the phases (initial mark, final re-mark) with the world stopped. | |
| 1740 // Because of locking involved in stopping the world, | |
| 1741 // the foreground collector should not block waiting for the background | |
| 1742 // collector when it is doing a stop-the-world phase. The background | |
| 1743 // collector will yield the baton at an additional point just before | |
| 1744 // it enters a stop-the-world phase. Once the world is stopped, the | |
| 1745 // background collector checks the phase of the collection. If the | |
| 1746 // phase has not changed, it proceeds with the collection. If the | |
| 1747 // phase has changed, it skips that phase of the collection. See | |
| 1748 // the comments on the use of the Heap_lock in collect_in_background(). | |
| 1749 // | |
| 1750 // Variable used in baton passing. | |
| 1751 // _foregroundGCIsActive - Set to true by the foreground collector when | |
| 1752 // it wants the baton. The foreground clears it when it has finished | |
| 1753 // the collection. | |
| 1754 // _foregroundGCShouldWait - Set to true by the background collector | |
| 1755 // when it is running. The foreground collector waits while | |
| 1756 // _foregroundGCShouldWait is true. | |
| 1757 // CGC_lock - monitor used to protect access to the above variables | |
| 1758 // and to notify the foreground and background collectors. | |
| 1759 // _collectorState - current state of the CMS collection. | |
| 1760 // | |
| 1761 // The foreground collector | |
| 1762 // acquires the CGC_lock | |
| 1763 // sets _foregroundGCIsActive | |
| 1764 // waits on the CGC_lock for _foregroundGCShouldWait to be false | |
| 1765 // various locks acquired in preparation for the collection | |
| 1766 // are released so as not to block the background collector | |
| 1767 // that is in the midst of a collection | |
| 1768 // proceeds with the collection | |
| 1769 // clears _foregroundGCIsActive | |
| 1770 // returns | |
| 1771 // | |
| 1772 // The background collector in a loop iterating on the phases of the | |
| 1773 // collection | |
| 1774 // acquires the CGC_lock | |
| 1775 // sets _foregroundGCShouldWait | |
| 1776 // if _foregroundGCIsActive is set | |
| 1777 // clears _foregroundGCShouldWait, notifies _CGC_lock | |
| 1778 // waits on _CGC_lock for _foregroundGCIsActive to become false | |
| 1779 // and exits the loop. | |
| 1780 // otherwise | |
| 1781 // proceed with that phase of the collection | |
| 1782 // if the phase is a stop-the-world phase, | |
| 1783 // yield the baton once more just before enqueueing | |
| 1784 // the stop-world CMS operation (executed by the VM thread). | |
| 1785 // returns after all phases of the collection are done | |
| 1786 // | |
| 1787 | |
| 1788 void CMSCollector::acquire_control_and_collect(bool full, | |
| 1789 bool clear_all_soft_refs) { | |
| 1790 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); | |
| 1791 assert(!Thread::current()->is_ConcurrentGC_thread(), | |
| 1792 "shouldn't try to acquire control from self!"); | |
| 1793 | |
| 1794 // Start the protocol for acquiring control of the | |
| 1795 // collection from the background collector (aka CMS thread). | |
| 1796 assert(ConcurrentMarkSweepThread::vm_thread_has_cms_token(), | |
| 1797 "VM thread should have CMS token"); | |
| 1798 // Remember the possibly interrupted state of an ongoing | |
| 1799 // concurrent collection | |
| 1800 CollectorState first_state = _collectorState; | |
| 1801 | |
| 1802 // Signal to a possibly ongoing concurrent collection that | |
| 1803 // we want to do a foreground collection. | |
| 1804 _foregroundGCIsActive = true; | |
| 1805 | |
| 1806 // Disable incremental mode during a foreground collection. | |
| 1807 ICMSDisabler icms_disabler; | |
| 1808 | |
| 1809 // release locks and wait for a notify from the background collector | |
| 1810 // releasing the locks in only necessary for phases which | |
| 1811 // do yields to improve the granularity of the collection. | |
| 1812 assert_lock_strong(bitMapLock()); | |
| 1813 // We need to lock the Free list lock for the space that we are | |
| 1814 // currently collecting. | |
| 1815 assert(haveFreelistLocks(), "Must be holding free list locks"); | |
| 1816 bitMapLock()->unlock(); | |
| 1817 releaseFreelistLocks(); | |
| 1818 { | |
| 1819 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
| 1820 if (_foregroundGCShouldWait) { | |
| 1821 // We are going to be waiting for action for the CMS thread; | |
| 1822 // it had better not be gone (for instance at shutdown)! | |
| 1823 assert(ConcurrentMarkSweepThread::cmst() != NULL, | |
| 1824 "CMS thread must be running"); | |
| 1825 // Wait here until the background collector gives us the go-ahead | |
| 1826 ConcurrentMarkSweepThread::clear_CMS_flag( | |
| 1827 ConcurrentMarkSweepThread::CMS_vm_has_token); // release token | |
| 1828 // Get a possibly blocked CMS thread going: | |
| 1829 // Note that we set _foregroundGCIsActive true above, | |
| 1830 // without protection of the CGC_lock. | |
| 1831 CGC_lock->notify(); | |
| 1832 assert(!ConcurrentMarkSweepThread::vm_thread_wants_cms_token(), | |
| 1833 "Possible deadlock"); | |
| 1834 while (_foregroundGCShouldWait) { | |
| 1835 // wait for notification | |
| 1836 CGC_lock->wait(Mutex::_no_safepoint_check_flag); | |
| 1837 // Possibility of delay/starvation here, since CMS token does | |
| 1838 // not know to give priority to VM thread? Actually, i think | |
| 1839 // there wouldn't be any delay/starvation, but the proof of | |
| 1840 // that "fact" (?) appears non-trivial. XXX 20011219YSR | |
| 1841 } | |
| 1842 ConcurrentMarkSweepThread::set_CMS_flag( | |
| 1843 ConcurrentMarkSweepThread::CMS_vm_has_token); | |
| 1844 } | |
| 1845 } | |
| 1846 // The CMS_token is already held. Get back the other locks. | |
| 1847 assert(ConcurrentMarkSweepThread::vm_thread_has_cms_token(), | |
| 1848 "VM thread should have CMS token"); | |
| 1849 getFreelistLocks(); | |
| 1850 bitMapLock()->lock_without_safepoint_check(); | |
| 1851 if (TraceCMSState) { | |
| 1852 gclog_or_tty->print_cr("CMS foreground collector has asked for control " | |
| 1853 INTPTR_FORMAT " with first state %d", Thread::current(), first_state); | |
| 1854 gclog_or_tty->print_cr(" gets control with state %d", _collectorState); | |
| 1855 } | |
| 1856 | |
| 1857 // Check if we need to do a compaction, or if not, whether | |
| 1858 // we need to start the mark-sweep from scratch. | |
| 1859 bool should_compact = false; | |
| 1860 bool should_start_over = false; | |
| 1861 decide_foreground_collection_type(clear_all_soft_refs, | |
| 1862 &should_compact, &should_start_over); | |
| 1863 | |
| 1864 NOT_PRODUCT( | |
| 1865 if (RotateCMSCollectionTypes) { | |
| 1866 if (_cmsGen->debug_collection_type() == | |
| 1867 ConcurrentMarkSweepGeneration::MSC_foreground_collection_type) { | |
| 1868 should_compact = true; | |
| 1869 } else if (_cmsGen->debug_collection_type() == | |
| 1870 ConcurrentMarkSweepGeneration::MS_foreground_collection_type) { | |
| 1871 should_compact = false; | |
| 1872 } | |
| 1873 } | |
| 1874 ) | |
| 1875 | |
| 10405 | 1876 if (first_state > Idling) { |
| 1877 report_concurrent_mode_interruption(); | |
| 0 | 1878 } |
| 1879 | |
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1880 set_did_compact(should_compact); |
| 0 | 1881 if (should_compact) { |
| 1882 // If the collection is being acquired from the background | |
| 1883 // collector, there may be references on the discovered | |
| 1884 // references lists that have NULL referents (being those | |
| 1885 // that were concurrently cleared by a mutator) or | |
| 1886 // that are no longer active (having been enqueued concurrently | |
| 1887 // by the mutator). | |
| 1888 // Scrub the list of those references because Mark-Sweep-Compact | |
| 1889 // code assumes referents are not NULL and that all discovered | |
| 1890 // Reference objects are active. | |
| 1891 ref_processor()->clean_up_discovered_references(); | |
| 1892 | |
| 10405 | 1893 if (first_state > Idling) { |
| 1894 save_heap_summary(); | |
| 1895 } | |
| 1896 | |
| 0 | 1897 do_compaction_work(clear_all_soft_refs); |
| 1898 | |
| 1899 // Has the GC time limit been exceeded? | |
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1900 DefNewGeneration* young_gen = _young_gen->as_DefNewGeneration(); |
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1901 size_t max_eden_size = young_gen->max_capacity() - |
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1902 young_gen->to()->capacity() - |
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1903 young_gen->from()->capacity(); |
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1904 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
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1905 GCCause::Cause gc_cause = gch->gc_cause(); |
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1906 size_policy()->check_gc_overhead_limit(_young_gen->used(), |
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1907 young_gen->eden()->used(), |
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1908 _cmsGen->max_capacity(), |
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1909 max_eden_size, |
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1910 full, |
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1911 gc_cause, |
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1912 gch->collector_policy()); |
| 0 | 1913 } else { |
| 1914 do_mark_sweep_work(clear_all_soft_refs, first_state, | |
| 1915 should_start_over); | |
| 1916 } | |
| 1917 // Reset the expansion cause, now that we just completed | |
| 1918 // a collection cycle. | |
| 1919 clear_expansion_cause(); | |
| 1920 _foregroundGCIsActive = false; | |
| 1921 return; | |
| 1922 } | |
| 1923 | |
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1924 // Resize the tenured generation |
| 0 | 1925 // after obtaining the free list locks for the |
| 1926 // two generations. | |
| 1927 void CMSCollector::compute_new_size() { | |
| 1928 assert_locked_or_safepoint(Heap_lock); | |
| 1929 FreelistLocker z(this); | |
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1930 MetaspaceGC::compute_new_size(); |
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1931 _cmsGen->compute_new_size_free_list(); |
| 0 | 1932 } |
| 1933 | |
| 1934 // A work method used by foreground collection to determine | |
| 1935 // what type of collection (compacting or not, continuing or fresh) | |
| 1936 // it should do. | |
| 1937 // NOTE: the intent is to make UseCMSCompactAtFullCollection | |
| 1938 // and CMSCompactWhenClearAllSoftRefs the default in the future | |
| 1939 // and do away with the flags after a suitable period. | |
| 1940 void CMSCollector::decide_foreground_collection_type( | |
| 1941 bool clear_all_soft_refs, bool* should_compact, | |
| 1942 bool* should_start_over) { | |
| 1943 // Normally, we'll compact only if the UseCMSCompactAtFullCollection | |
| 1944 // flag is set, and we have either requested a System.gc() or | |
| 1945 // the number of full gc's since the last concurrent cycle | |
| 1946 // has exceeded the threshold set by CMSFullGCsBeforeCompaction, | |
| 1947 // or if an incremental collection has failed | |
| 1948 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 1949 assert(gch->collector_policy()->is_two_generation_policy(), | |
| 1950 "You may want to check the correctness of the following"); | |
| 1951 // Inform cms gen if this was due to partial collection failing. | |
| 1952 // The CMS gen may use this fact to determine its expansion policy. | |
|
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1953 if (gch->incremental_collection_will_fail(false /* don't consult_young */)) { |
| 0 | 1954 assert(!_cmsGen->incremental_collection_failed(), |
| 1955 "Should have been noticed, reacted to and cleared"); | |
| 1956 _cmsGen->set_incremental_collection_failed(); | |
| 1957 } | |
| 1958 *should_compact = | |
| 1959 UseCMSCompactAtFullCollection && | |
| 1960 ((_full_gcs_since_conc_gc >= CMSFullGCsBeforeCompaction) || | |
| 1961 GCCause::is_user_requested_gc(gch->gc_cause()) || | |
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1962 gch->incremental_collection_will_fail(true /* consult_young */)); |
| 0 | 1963 *should_start_over = false; |
| 1964 if (clear_all_soft_refs && !*should_compact) { | |
| 1965 // We are about to do a last ditch collection attempt | |
| 1966 // so it would normally make sense to do a compaction | |
| 1967 // to reclaim as much space as possible. | |
| 1968 if (CMSCompactWhenClearAllSoftRefs) { | |
| 1969 // Default: The rationale is that in this case either | |
| 1970 // we are past the final marking phase, in which case | |
| 1971 // we'd have to start over, or so little has been done | |
| 1972 // that there's little point in saving that work. Compaction | |
| 1973 // appears to be the sensible choice in either case. | |
| 1974 *should_compact = true; | |
| 1975 } else { | |
| 1976 // We have been asked to clear all soft refs, but not to | |
| 1977 // compact. Make sure that we aren't past the final checkpoint | |
| 1978 // phase, for that is where we process soft refs. If we are already | |
| 1979 // past that phase, we'll need to redo the refs discovery phase and | |
| 1980 // if necessary clear soft refs that weren't previously | |
| 1981 // cleared. We do so by remembering the phase in which | |
| 1982 // we came in, and if we are past the refs processing | |
| 1983 // phase, we'll choose to just redo the mark-sweep | |
| 1984 // collection from scratch. | |
| 1985 if (_collectorState > FinalMarking) { | |
| 1986 // We are past the refs processing phase; | |
| 1987 // start over and do a fresh synchronous CMS cycle | |
| 1988 _collectorState = Resetting; // skip to reset to start new cycle | |
| 1989 reset(false /* == !asynch */); | |
| 1990 *should_start_over = true; | |
| 1991 } // else we can continue a possibly ongoing current cycle | |
| 1992 } | |
| 1993 } | |
| 1994 } | |
| 1995 | |
| 1996 // A work method used by the foreground collector to do | |
| 1997 // a mark-sweep-compact. | |
| 1998 void CMSCollector::do_compaction_work(bool clear_all_soft_refs) { | |
| 1999 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 10405 | 2000 |
| 2001 STWGCTimer* gc_timer = GenMarkSweep::gc_timer(); | |
| 2002 gc_timer->register_gc_start(os::elapsed_counter()); | |
| 2003 | |
| 2004 SerialOldTracer* gc_tracer = GenMarkSweep::gc_tracer(); | |
| 2005 gc_tracer->report_gc_start(gch->gc_cause(), gc_timer->gc_start()); | |
| 2006 | |
| 2007 GCTraceTime t("CMS:MSC ", PrintGCDetails && Verbose, true, NULL); | |
| 0 | 2008 if (PrintGC && Verbose && !(GCCause::is_user_requested_gc(gch->gc_cause()))) { |
| 2009 gclog_or_tty->print_cr("Compact ConcurrentMarkSweepGeneration after %d " | |
| 2010 "collections passed to foreground collector", _full_gcs_since_conc_gc); | |
| 2011 } | |
| 2012 | |
| 2013 // Sample collection interval time and reset for collection pause. | |
| 2014 if (UseAdaptiveSizePolicy) { | |
| 2015 size_policy()->msc_collection_begin(); | |
| 2016 } | |
| 2017 | |
| 2018 // Temporarily widen the span of the weak reference processing to | |
| 2019 // the entire heap. | |
| 2020 MemRegion new_span(GenCollectedHeap::heap()->reserved_region()); | |
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2021 ReferenceProcessorSpanMutator rp_mut_span(ref_processor(), new_span); |
| 0 | 2022 // Temporarily, clear the "is_alive_non_header" field of the |
| 2023 // reference processor. | |
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2024 ReferenceProcessorIsAliveMutator rp_mut_closure(ref_processor(), NULL); |
| 0 | 2025 // Temporarily make reference _processing_ single threaded (non-MT). |
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2026 ReferenceProcessorMTProcMutator rp_mut_mt_processing(ref_processor(), false); |
| 0 | 2027 // Temporarily make refs discovery atomic |
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2028 ReferenceProcessorAtomicMutator rp_mut_atomic(ref_processor(), true); |
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2029 // Temporarily make reference _discovery_ single threaded (non-MT) |
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2030 ReferenceProcessorMTDiscoveryMutator rp_mut_discovery(ref_processor(), false); |
| 0 | 2031 |
| 2032 ref_processor()->set_enqueuing_is_done(false); | |
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2033 ref_processor()->enable_discovery(false /*verify_disabled*/, false /*check_no_refs*/); |
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2034 ref_processor()->setup_policy(clear_all_soft_refs); |
| 0 | 2035 // If an asynchronous collection finishes, the _modUnionTable is |
| 2036 // all clear. If we are assuming the collection from an asynchronous | |
| 2037 // collection, clear the _modUnionTable. | |
| 2038 assert(_collectorState != Idling || _modUnionTable.isAllClear(), | |
| 2039 "_modUnionTable should be clear if the baton was not passed"); | |
| 2040 _modUnionTable.clear_all(); | |
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2041 assert(_collectorState != Idling || _ct->klass_rem_set()->mod_union_is_clear(), |
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2042 "mod union for klasses should be clear if the baton was passed"); |
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2043 _ct->klass_rem_set()->clear_mod_union(); |
| 0 | 2044 |
| 2045 // We must adjust the allocation statistics being maintained | |
| 2046 // in the free list space. We do so by reading and clearing | |
| 2047 // the sweep timer and updating the block flux rate estimates below. | |
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2048 assert(!_intra_sweep_timer.is_active(), "_intra_sweep_timer should be inactive"); |
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2049 if (_inter_sweep_timer.is_active()) { |
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2050 _inter_sweep_timer.stop(); |
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2051 // Note that we do not use this sample to update the _inter_sweep_estimate. |
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2052 _cmsGen->cmsSpace()->beginSweepFLCensus((float)(_inter_sweep_timer.seconds()), |
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2053 _inter_sweep_estimate.padded_average(), |
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2054 _intra_sweep_estimate.padded_average()); |
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2055 } |
| 0 | 2056 |
| 2057 GenMarkSweep::invoke_at_safepoint(_cmsGen->level(), | |
| 2058 ref_processor(), clear_all_soft_refs); | |
| 2059 #ifdef ASSERT | |
| 2060 CompactibleFreeListSpace* cms_space = _cmsGen->cmsSpace(); | |
| 2061 size_t free_size = cms_space->free(); | |
| 2062 assert(free_size == | |
| 2063 pointer_delta(cms_space->end(), cms_space->compaction_top()) | |
| 2064 * HeapWordSize, | |
| 2065 "All the free space should be compacted into one chunk at top"); | |
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2066 assert(cms_space->dictionary()->total_chunk_size( |
| 0 | 2067 debug_only(cms_space->freelistLock())) == 0 || |
| 2068 cms_space->totalSizeInIndexedFreeLists() == 0, | |
| 2069 "All the free space should be in a single chunk"); | |
| 2070 size_t num = cms_space->totalCount(); | |
| 2071 assert((free_size == 0 && num == 0) || | |
| 2072 (free_size > 0 && (num == 1 || num == 2)), | |
| 2073 "There should be at most 2 free chunks after compaction"); | |
| 2074 #endif // ASSERT | |
| 2075 _collectorState = Resetting; | |
| 2076 assert(_restart_addr == NULL, | |
| 2077 "Should have been NULL'd before baton was passed"); | |
| 2078 reset(false /* == !asynch */); | |
| 2079 _cmsGen->reset_after_compaction(); | |
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2080 _concurrent_cycles_since_last_unload = 0; |
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2081 |
| 0 | 2082 // Clear any data recorded in the PLAB chunk arrays. |
| 2083 if (_survivor_plab_array != NULL) { | |
| 2084 reset_survivor_plab_arrays(); | |
| 2085 } | |
| 2086 | |
| 2087 // Adjust the per-size allocation stats for the next epoch. | |
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2088 _cmsGen->cmsSpace()->endSweepFLCensus(sweep_count() /* fake */); |
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2089 // Restart the "inter sweep timer" for the next epoch. |
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2090 _inter_sweep_timer.reset(); |
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2091 _inter_sweep_timer.start(); |
| 0 | 2092 |
| 2093 // Sample collection pause time and reset for collection interval. | |
| 2094 if (UseAdaptiveSizePolicy) { | |
| 2095 size_policy()->msc_collection_end(gch->gc_cause()); | |
| 2096 } | |
| 2097 | |
| 10405 | 2098 gc_timer->register_gc_end(os::elapsed_counter()); |
| 2099 | |
| 2100 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); | |
| 2101 | |
| 0 | 2102 // For a mark-sweep-compact, compute_new_size() will be called |
| 2103 // in the heap's do_collection() method. | |
| 2104 } | |
| 2105 | |
| 2106 // A work method used by the foreground collector to do | |
| 2107 // a mark-sweep, after taking over from a possibly on-going | |
| 2108 // concurrent mark-sweep collection. | |
| 2109 void CMSCollector::do_mark_sweep_work(bool clear_all_soft_refs, | |
| 2110 CollectorState first_state, bool should_start_over) { | |
| 2111 if (PrintGC && Verbose) { | |
| 2112 gclog_or_tty->print_cr("Pass concurrent collection to foreground " | |
| 2113 "collector with count %d", | |
| 2114 _full_gcs_since_conc_gc); | |
| 2115 } | |
| 2116 switch (_collectorState) { | |
| 2117 case Idling: | |
| 2118 if (first_state == Idling || should_start_over) { | |
| 2119 // The background GC was not active, or should | |
| 2120 // restarted from scratch; start the cycle. | |
| 2121 _collectorState = InitialMarking; | |
| 2122 } | |
| 2123 // If first_state was not Idling, then a background GC | |
| 2124 // was in progress and has now finished. No need to do it | |
| 2125 // again. Leave the state as Idling. | |
| 2126 break; | |
| 2127 case Precleaning: | |
| 2128 // In the foreground case don't do the precleaning since | |
| 2129 // it is not done concurrently and there is extra work | |
| 2130 // required. | |
| 2131 _collectorState = FinalMarking; | |
| 2132 } | |
| 10405 | 2133 collect_in_foreground(clear_all_soft_refs, GenCollectedHeap::heap()->gc_cause()); |
| 0 | 2134 |
| 2135 // For a mark-sweep, compute_new_size() will be called | |
| 2136 // in the heap's do_collection() method. | |
| 2137 } | |
| 2138 | |
| 2139 | |
| 2140 void CMSCollector::getFreelistLocks() const { | |
| 2141 // Get locks for all free lists in all generations that this | |
| 2142 // collector is responsible for | |
| 2143 _cmsGen->freelistLock()->lock_without_safepoint_check(); | |
| 2144 } | |
| 2145 | |
| 2146 void CMSCollector::releaseFreelistLocks() const { | |
| 2147 // Release locks for all free lists in all generations that this | |
| 2148 // collector is responsible for | |
| 2149 _cmsGen->freelistLock()->unlock(); | |
| 2150 } | |
| 2151 | |
| 2152 bool CMSCollector::haveFreelistLocks() const { | |
| 2153 // Check locks for all free lists in all generations that this | |
| 2154 // collector is responsible for | |
| 2155 assert_lock_strong(_cmsGen->freelistLock()); | |
| 2156 PRODUCT_ONLY(ShouldNotReachHere()); | |
| 2157 return true; | |
| 2158 } | |
| 2159 | |
| 2160 // A utility class that is used by the CMS collector to | |
| 2161 // temporarily "release" the foreground collector from its | |
| 2162 // usual obligation to wait for the background collector to | |
| 2163 // complete an ongoing phase before proceeding. | |
| 2164 class ReleaseForegroundGC: public StackObj { | |
| 2165 private: | |
| 2166 CMSCollector* _c; | |
| 2167 public: | |
| 2168 ReleaseForegroundGC(CMSCollector* c) : _c(c) { | |
| 2169 assert(_c->_foregroundGCShouldWait, "Else should not need to call"); | |
| 2170 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
| 2171 // allow a potentially blocked foreground collector to proceed | |
| 2172 _c->_foregroundGCShouldWait = false; | |
| 2173 if (_c->_foregroundGCIsActive) { | |
| 2174 CGC_lock->notify(); | |
| 2175 } | |
| 2176 assert(!ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 2177 "Possible deadlock"); | |
| 2178 } | |
| 2179 | |
| 2180 ~ReleaseForegroundGC() { | |
| 2181 assert(!_c->_foregroundGCShouldWait, "Usage protocol violation?"); | |
| 2182 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
| 2183 _c->_foregroundGCShouldWait = true; | |
| 2184 } | |
| 2185 }; | |
| 2186 | |
| 2187 // There are separate collect_in_background and collect_in_foreground because of | |
| 2188 // the different locking requirements of the background collector and the | |
| 2189 // foreground collector. There was originally an attempt to share | |
| 2190 // one "collect" method between the background collector and the foreground | |
| 2191 // collector but the if-then-else required made it cleaner to have | |
| 2192 // separate methods. | |
| 10405 | 2193 void CMSCollector::collect_in_background(bool clear_all_soft_refs, GCCause::Cause cause) { |
| 0 | 2194 assert(Thread::current()->is_ConcurrentGC_thread(), |
| 2195 "A CMS asynchronous collection is only allowed on a CMS thread."); | |
| 2196 | |
| 2197 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 2198 { | |
| 2199 bool safepoint_check = Mutex::_no_safepoint_check_flag; | |
| 2200 MutexLockerEx hl(Heap_lock, safepoint_check); | |
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2201 FreelistLocker fll(this); |
| 0 | 2202 MutexLockerEx x(CGC_lock, safepoint_check); |
| 2203 if (_foregroundGCIsActive || !UseAsyncConcMarkSweepGC) { | |
| 2204 // The foreground collector is active or we're | |
| 2205 // not using asynchronous collections. Skip this | |
| 2206 // background collection. | |
| 2207 assert(!_foregroundGCShouldWait, "Should be clear"); | |
| 2208 return; | |
| 2209 } else { | |
| 2210 assert(_collectorState == Idling, "Should be idling before start."); | |
| 2211 _collectorState = InitialMarking; | |
| 10405 | 2212 register_gc_start(cause); |
| 0 | 2213 // Reset the expansion cause, now that we are about to begin |
| 2214 // a new cycle. | |
| 2215 clear_expansion_cause(); | |
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2216 |
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2217 // Clear the MetaspaceGC flag since a concurrent collection |
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2218 // is starting but also clear it after the collection. |
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2219 MetaspaceGC::set_should_concurrent_collect(false); |
| 0 | 2220 } |
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2221 // Decide if we want to enable class unloading as part of the |
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2222 // ensuing concurrent GC cycle. |
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2223 update_should_unload_classes(); |
| 0 | 2224 _full_gc_requested = false; // acks all outstanding full gc requests |
| 10405 | 2225 _full_gc_cause = GCCause::_no_gc; |
| 0 | 2226 // Signal that we are about to start a collection |
| 2227 gch->increment_total_full_collections(); // ... starting a collection cycle | |
| 2228 _collection_count_start = gch->total_full_collections(); | |
| 2229 } | |
| 2230 | |
| 2231 // Used for PrintGC | |
| 2232 size_t prev_used; | |
| 2233 if (PrintGC && Verbose) { | |
| 2234 prev_used = _cmsGen->used(); // XXXPERM | |
| 2235 } | |
| 2236 | |
| 2237 // The change of the collection state is normally done at this level; | |
| 2238 // the exceptions are phases that are executed while the world is | |
| 2239 // stopped. For those phases the change of state is done while the | |
| 2240 // world is stopped. For baton passing purposes this allows the | |
| 2241 // background collector to finish the phase and change state atomically. | |
| 2242 // The foreground collector cannot wait on a phase that is done | |
| 2243 // while the world is stopped because the foreground collector already | |
| 2244 // has the world stopped and would deadlock. | |
| 2245 while (_collectorState != Idling) { | |
| 2246 if (TraceCMSState) { | |
| 2247 gclog_or_tty->print_cr("Thread " INTPTR_FORMAT " in CMS state %d", | |
| 2248 Thread::current(), _collectorState); | |
| 2249 } | |
| 2250 // The foreground collector | |
| 2251 // holds the Heap_lock throughout its collection. | |
| 2252 // holds the CMS token (but not the lock) | |
| 2253 // except while it is waiting for the background collector to yield. | |
| 2254 // | |
| 2255 // The foreground collector should be blocked (not for long) | |
| 2256 // if the background collector is about to start a phase | |
| 2257 // executed with world stopped. If the background | |
| 2258 // collector has already started such a phase, the | |
| 2259 // foreground collector is blocked waiting for the | |
| 2260 // Heap_lock. The stop-world phases (InitialMarking and FinalMarking) | |
| 2261 // are executed in the VM thread. | |
| 2262 // | |
| 2263 // The locking order is | |
| 2264 // PendingListLock (PLL) -- if applicable (FinalMarking) | |
| 2265 // Heap_lock (both this & PLL locked in VM_CMS_Operation::prologue()) | |
| 2266 // CMS token (claimed in | |
| 2267 // stop_world_and_do() --> | |
| 2268 // safepoint_synchronize() --> | |
| 2269 // CMSThread::synchronize()) | |
| 2270 | |
| 2271 { | |
| 2272 // Check if the FG collector wants us to yield. | |
| 2273 CMSTokenSync x(true); // is cms thread | |
| 2274 if (waitForForegroundGC()) { | |
| 2275 // We yielded to a foreground GC, nothing more to be | |
| 2276 // done this round. | |
| 2277 assert(_foregroundGCShouldWait == false, "We set it to false in " | |
| 2278 "waitForForegroundGC()"); | |
| 2279 if (TraceCMSState) { | |
| 2280 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT | |
| 2281 " exiting collection CMS state %d", | |
| 2282 Thread::current(), _collectorState); | |
| 2283 } | |
| 2284 return; | |
| 2285 } else { | |
| 2286 // The background collector can run but check to see if the | |
| 2287 // foreground collector has done a collection while the | |
| 2288 // background collector was waiting to get the CGC_lock | |
| 2289 // above. If yes, break so that _foregroundGCShouldWait | |
| 2290 // is cleared before returning. | |
| 2291 if (_collectorState == Idling) { | |
| 2292 break; | |
| 2293 } | |
| 2294 } | |
| 2295 } | |
| 2296 | |
| 2297 assert(_foregroundGCShouldWait, "Foreground collector, if active, " | |
| 2298 "should be waiting"); | |
| 2299 | |
| 2300 switch (_collectorState) { | |
| 2301 case InitialMarking: | |
| 2302 { | |
| 2303 ReleaseForegroundGC x(this); | |
| 2304 stats().record_cms_begin(); | |
| 2305 VM_CMS_Initial_Mark initial_mark_op(this); | |
| 2306 VMThread::execute(&initial_mark_op); | |
| 2307 } | |
| 2308 // The collector state may be any legal state at this point | |
| 2309 // since the background collector may have yielded to the | |
| 2310 // foreground collector. | |
| 2311 break; | |
| 2312 case Marking: | |
| 2313 // initial marking in checkpointRootsInitialWork has been completed | |
| 2314 if (markFromRoots(true)) { // we were successful | |
| 2315 assert(_collectorState == Precleaning, "Collector state should " | |
| 2316 "have changed"); | |
| 2317 } else { | |
| 2318 assert(_foregroundGCIsActive, "Internal state inconsistency"); | |
| 2319 } | |
| 2320 break; | |
| 2321 case Precleaning: | |
| 2322 if (UseAdaptiveSizePolicy) { | |
| 2323 size_policy()->concurrent_precleaning_begin(); | |
| 2324 } | |
| 2325 // marking from roots in markFromRoots has been completed | |
| 2326 preclean(); | |
| 2327 if (UseAdaptiveSizePolicy) { | |
| 2328 size_policy()->concurrent_precleaning_end(); | |
| 2329 } | |
| 2330 assert(_collectorState == AbortablePreclean || | |
| 2331 _collectorState == FinalMarking, | |
| 2332 "Collector state should have changed"); | |
| 2333 break; | |
| 2334 case AbortablePreclean: | |
| 2335 if (UseAdaptiveSizePolicy) { | |
| 2336 size_policy()->concurrent_phases_resume(); | |
| 2337 } | |
| 2338 abortable_preclean(); | |
| 2339 if (UseAdaptiveSizePolicy) { | |
| 2340 size_policy()->concurrent_precleaning_end(); | |
| 2341 } | |
| 2342 assert(_collectorState == FinalMarking, "Collector state should " | |
| 2343 "have changed"); | |
| 2344 break; | |
| 2345 case FinalMarking: | |
| 2346 { | |
| 2347 ReleaseForegroundGC x(this); | |
| 2348 | |
| 2349 VM_CMS_Final_Remark final_remark_op(this); | |
| 2350 VMThread::execute(&final_remark_op); | |
| 935 | 2351 } |
| 0 | 2352 assert(_foregroundGCShouldWait, "block post-condition"); |
| 2353 break; | |
| 2354 case Sweeping: | |
| 2355 if (UseAdaptiveSizePolicy) { | |
| 2356 size_policy()->concurrent_sweeping_begin(); | |
| 2357 } | |
| 2358 // final marking in checkpointRootsFinal has been completed | |
| 2359 sweep(true); | |
| 2360 assert(_collectorState == Resizing, "Collector state change " | |
| 2361 "to Resizing must be done under the free_list_lock"); | |
| 2362 _full_gcs_since_conc_gc = 0; | |
| 2363 | |
| 2364 // Stop the timers for adaptive size policy for the concurrent phases | |
| 2365 if (UseAdaptiveSizePolicy) { | |
| 2366 size_policy()->concurrent_sweeping_end(); | |
| 2367 size_policy()->concurrent_phases_end(gch->gc_cause(), | |
| 2368 gch->prev_gen(_cmsGen)->capacity(), | |
| 2369 _cmsGen->free()); | |
| 2370 } | |
| 2371 | |
| 2372 case Resizing: { | |
| 2373 // Sweeping has been completed... | |
| 2374 // At this point the background collection has completed. | |
| 2375 // Don't move the call to compute_new_size() down | |
| 2376 // into code that might be executed if the background | |
| 2377 // collection was preempted. | |
| 2378 { | |
| 2379 ReleaseForegroundGC x(this); // unblock FG collection | |
| 2380 MutexLockerEx y(Heap_lock, Mutex::_no_safepoint_check_flag); | |
| 2381 CMSTokenSync z(true); // not strictly needed. | |
| 2382 if (_collectorState == Resizing) { | |
| 2383 compute_new_size(); | |
| 10405 | 2384 save_heap_summary(); |
| 0 | 2385 _collectorState = Resetting; |
| 2386 } else { | |
| 2387 assert(_collectorState == Idling, "The state should only change" | |
| 2388 " because the foreground collector has finished the collection"); | |
| 2389 } | |
| 2390 } | |
| 2391 break; | |
| 2392 } | |
| 2393 case Resetting: | |
| 2394 // CMS heap resizing has been completed | |
| 2395 reset(true); | |
| 2396 assert(_collectorState == Idling, "Collector state should " | |
| 2397 "have changed"); | |
|
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2398 |
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2399 MetaspaceGC::set_should_concurrent_collect(false); |
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2400 |
| 0 | 2401 stats().record_cms_end(); |
| 2402 // Don't move the concurrent_phases_end() and compute_new_size() | |
| 2403 // calls to here because a preempted background collection | |
| 2404 // has it's state set to "Resetting". | |
| 2405 break; | |
| 2406 case Idling: | |
| 2407 default: | |
| 2408 ShouldNotReachHere(); | |
| 2409 break; | |
| 2410 } | |
| 2411 if (TraceCMSState) { | |
| 2412 gclog_or_tty->print_cr(" Thread " INTPTR_FORMAT " done - next CMS state %d", | |
| 2413 Thread::current(), _collectorState); | |
| 2414 } | |
| 2415 assert(_foregroundGCShouldWait, "block post-condition"); | |
| 2416 } | |
| 2417 | |
| 2418 // Should this be in gc_epilogue? | |
| 2419 collector_policy()->counters()->update_counters(); | |
| 2420 | |
| 2421 { | |
| 2422 // Clear _foregroundGCShouldWait and, in the event that the | |
| 2423 // foreground collector is waiting, notify it, before | |
| 2424 // returning. | |
| 2425 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
| 2426 _foregroundGCShouldWait = false; | |
| 2427 if (_foregroundGCIsActive) { | |
| 2428 CGC_lock->notify(); | |
| 2429 } | |
| 2430 assert(!ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 2431 "Possible deadlock"); | |
| 2432 } | |
| 2433 if (TraceCMSState) { | |
| 2434 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT | |
| 2435 " exiting collection CMS state %d", | |
| 2436 Thread::current(), _collectorState); | |
| 2437 } | |
| 2438 if (PrintGC && Verbose) { | |
| 2439 _cmsGen->print_heap_change(prev_used); | |
| 2440 } | |
| 2441 } | |
| 2442 | |
| 10405 | 2443 void CMSCollector::register_foreground_gc_start(GCCause::Cause cause) { |
| 2444 if (!_cms_start_registered) { | |
| 2445 register_gc_start(cause); | |
| 2446 } | |
| 2447 } | |
| 2448 | |
| 2449 void CMSCollector::register_gc_start(GCCause::Cause cause) { | |
| 2450 _cms_start_registered = true; | |
| 2451 _gc_timer_cm->register_gc_start(os::elapsed_counter()); | |
| 2452 _gc_tracer_cm->report_gc_start(cause, _gc_timer_cm->gc_start()); | |
| 2453 } | |
| 2454 | |
| 2455 void CMSCollector::register_gc_end() { | |
| 2456 if (_cms_start_registered) { | |
| 2457 report_heap_summary(GCWhen::AfterGC); | |
| 2458 | |
| 2459 _gc_timer_cm->register_gc_end(os::elapsed_counter()); | |
| 2460 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); | |
| 2461 _cms_start_registered = false; | |
| 2462 } | |
| 2463 } | |
| 2464 | |
| 2465 void CMSCollector::save_heap_summary() { | |
| 2466 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 2467 _last_heap_summary = gch->create_heap_summary(); | |
| 2468 _last_metaspace_summary = gch->create_metaspace_summary(); | |
| 2469 } | |
| 2470 | |
| 2471 void CMSCollector::report_heap_summary(GCWhen::Type when) { | |
| 2472 _gc_tracer_cm->report_gc_heap_summary(when, _last_heap_summary, _last_metaspace_summary); | |
| 2473 } | |
| 2474 | |
| 2475 void CMSCollector::collect_in_foreground(bool clear_all_soft_refs, GCCause::Cause cause) { | |
| 0 | 2476 assert(_foregroundGCIsActive && !_foregroundGCShouldWait, |
| 2477 "Foreground collector should be waiting, not executing"); | |
| 2478 assert(Thread::current()->is_VM_thread(), "A foreground collection" | |
| 2479 "may only be done by the VM Thread with the world stopped"); | |
| 2480 assert(ConcurrentMarkSweepThread::vm_thread_has_cms_token(), | |
| 2481 "VM thread should have CMS token"); | |
| 2482 | |
| 10405 | 2483 NOT_PRODUCT(GCTraceTime t("CMS:MS (foreground) ", PrintGCDetails && Verbose, |
| 2484 true, NULL);) | |
| 0 | 2485 if (UseAdaptiveSizePolicy) { |
| 2486 size_policy()->ms_collection_begin(); | |
| 2487 } | |
| 2488 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact); | |
| 2489 | |
| 2490 HandleMark hm; // Discard invalid handles created during verification | |
| 2491 | |
| 2492 if (VerifyBeforeGC && | |
| 2493 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
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2494 Universe::verify(); |
| 0 | 2495 } |
| 2496 | |
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2497 // Snapshot the soft reference policy to be used in this collection cycle. |
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2498 ref_processor()->setup_policy(clear_all_soft_refs); |
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2499 |
| 0 | 2500 bool init_mark_was_synchronous = false; // until proven otherwise |
| 2501 while (_collectorState != Idling) { | |
| 2502 if (TraceCMSState) { | |
| 2503 gclog_or_tty->print_cr("Thread " INTPTR_FORMAT " in CMS state %d", | |
| 2504 Thread::current(), _collectorState); | |
| 2505 } | |
| 2506 switch (_collectorState) { | |
| 2507 case InitialMarking: | |
| 10405 | 2508 register_foreground_gc_start(cause); |
| 0 | 2509 init_mark_was_synchronous = true; // fact to be exploited in re-mark |
| 2510 checkpointRootsInitial(false); | |
| 2511 assert(_collectorState == Marking, "Collector state should have changed" | |
| 2512 " within checkpointRootsInitial()"); | |
| 2513 break; | |
| 2514 case Marking: | |
| 2515 // initial marking in checkpointRootsInitialWork has been completed | |
| 2516 if (VerifyDuringGC && | |
| 2517 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
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2518 Universe::verify("Verify before initial mark: "); |
| 0 | 2519 } |
| 2520 { | |
| 2521 bool res = markFromRoots(false); | |
| 2522 assert(res && _collectorState == FinalMarking, "Collector state should " | |
| 2523 "have changed"); | |
| 2524 break; | |
| 2525 } | |
| 2526 case FinalMarking: | |
| 2527 if (VerifyDuringGC && | |
| 2528 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
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2529 Universe::verify("Verify before re-mark: "); |
| 0 | 2530 } |
| 2531 checkpointRootsFinal(false, clear_all_soft_refs, | |
| 2532 init_mark_was_synchronous); | |
| 2533 assert(_collectorState == Sweeping, "Collector state should not " | |
| 2534 "have changed within checkpointRootsFinal()"); | |
| 2535 break; | |
| 2536 case Sweeping: | |
| 2537 // final marking in checkpointRootsFinal has been completed | |
| 2538 if (VerifyDuringGC && | |
| 2539 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
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2540 Universe::verify("Verify before sweep: "); |
| 0 | 2541 } |
| 2542 sweep(false); | |
| 2543 assert(_collectorState == Resizing, "Incorrect state"); | |
| 2544 break; | |
| 2545 case Resizing: { | |
| 2546 // Sweeping has been completed; the actual resize in this case | |
| 2547 // is done separately; nothing to be done in this state. | |
| 2548 _collectorState = Resetting; | |
| 2549 break; | |
| 2550 } | |
| 2551 case Resetting: | |
| 2552 // The heap has been resized. | |
| 2553 if (VerifyDuringGC && | |
| 2554 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
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2555 Universe::verify("Verify before reset: "); |
| 0 | 2556 } |
| 10405 | 2557 save_heap_summary(); |
| 0 | 2558 reset(false); |
| 2559 assert(_collectorState == Idling, "Collector state should " | |
| 2560 "have changed"); | |
| 2561 break; | |
| 2562 case Precleaning: | |
| 2563 case AbortablePreclean: | |
| 2564 // Elide the preclean phase | |
| 2565 _collectorState = FinalMarking; | |
| 2566 break; | |
| 2567 default: | |
| 2568 ShouldNotReachHere(); | |
| 2569 } | |
| 2570 if (TraceCMSState) { | |
| 2571 gclog_or_tty->print_cr(" Thread " INTPTR_FORMAT " done - next CMS state %d", | |
| 2572 Thread::current(), _collectorState); | |
| 2573 } | |
| 2574 } | |
| 2575 | |
| 2576 if (UseAdaptiveSizePolicy) { | |
| 2577 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 2578 size_policy()->ms_collection_end(gch->gc_cause()); | |
| 2579 } | |
| 2580 | |
| 2581 if (VerifyAfterGC && | |
| 2582 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
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2583 Universe::verify(); |
| 0 | 2584 } |
| 2585 if (TraceCMSState) { | |
| 2586 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT | |
| 2587 " exiting collection CMS state %d", | |
| 2588 Thread::current(), _collectorState); | |
| 2589 } | |
| 2590 } | |
| 2591 | |
| 2592 bool CMSCollector::waitForForegroundGC() { | |
| 2593 bool res = false; | |
| 2594 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 2595 "CMS thread should have CMS token"); | |
| 2596 // Block the foreground collector until the | |
| 2597 // background collectors decides whether to | |
| 2598 // yield. | |
| 2599 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
| 2600 _foregroundGCShouldWait = true; | |
| 2601 if (_foregroundGCIsActive) { | |
| 2602 // The background collector yields to the | |
| 2603 // foreground collector and returns a value | |
| 2604 // indicating that it has yielded. The foreground | |
| 2605 // collector can proceed. | |
| 2606 res = true; | |
| 2607 _foregroundGCShouldWait = false; | |
| 2608 ConcurrentMarkSweepThread::clear_CMS_flag( | |
| 2609 ConcurrentMarkSweepThread::CMS_cms_has_token); | |
| 2610 ConcurrentMarkSweepThread::set_CMS_flag( | |
| 2611 ConcurrentMarkSweepThread::CMS_cms_wants_token); | |
| 2612 // Get a possibly blocked foreground thread going | |
| 2613 CGC_lock->notify(); | |
| 2614 if (TraceCMSState) { | |
| 2615 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT " waiting at CMS state %d", | |
| 2616 Thread::current(), _collectorState); | |
| 2617 } | |
| 2618 while (_foregroundGCIsActive) { | |
| 2619 CGC_lock->wait(Mutex::_no_safepoint_check_flag); | |
| 2620 } | |
| 2621 ConcurrentMarkSweepThread::set_CMS_flag( | |
| 2622 ConcurrentMarkSweepThread::CMS_cms_has_token); | |
| 2623 ConcurrentMarkSweepThread::clear_CMS_flag( | |
| 2624 ConcurrentMarkSweepThread::CMS_cms_wants_token); | |
| 2625 } | |
| 2626 if (TraceCMSState) { | |
| 2627 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT " continuing at CMS state %d", | |
| 2628 Thread::current(), _collectorState); | |
| 2629 } | |
| 2630 return res; | |
| 2631 } | |
| 2632 | |
| 2633 // Because of the need to lock the free lists and other structures in | |
| 2634 // the collector, common to all the generations that the collector is | |
| 2635 // collecting, we need the gc_prologues of individual CMS generations | |
| 2636 // delegate to their collector. It may have been simpler had the | |
| 2637 // current infrastructure allowed one to call a prologue on a | |
| 2638 // collector. In the absence of that we have the generation's | |
| 2639 // prologue delegate to the collector, which delegates back | |
| 2640 // some "local" work to a worker method in the individual generations | |
| 2641 // that it's responsible for collecting, while itself doing any | |
| 2642 // work common to all generations it's responsible for. A similar | |
| 2643 // comment applies to the gc_epilogue()'s. | |
| 2644 // The role of the varaible _between_prologue_and_epilogue is to | |
| 2645 // enforce the invocation protocol. | |
| 2646 void CMSCollector::gc_prologue(bool full) { | |
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2647 // Call gc_prologue_work() for the CMSGen |
| 0 | 2648 // we are responsible for. |
| 2649 | |
| 2650 // The following locking discipline assumes that we are only called | |
| 2651 // when the world is stopped. | |
| 2652 assert(SafepointSynchronize::is_at_safepoint(), "world is stopped assumption"); | |
| 2653 | |
| 2654 // The CMSCollector prologue must call the gc_prologues for the | |
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2655 // "generations" that it's responsible |
| 0 | 2656 // for. |
| 2657 | |
| 2658 assert( Thread::current()->is_VM_thread() | |
| 2659 || ( CMSScavengeBeforeRemark | |
| 2660 && Thread::current()->is_ConcurrentGC_thread()), | |
| 2661 "Incorrect thread type for prologue execution"); | |
| 2662 | |
| 2663 if (_between_prologue_and_epilogue) { | |
| 2664 // We have already been invoked; this is a gc_prologue delegation | |
| 2665 // from yet another CMS generation that we are responsible for, just | |
| 2666 // ignore it since all relevant work has already been done. | |
| 2667 return; | |
| 2668 } | |
| 2669 | |
| 2670 // set a bit saying prologue has been called; cleared in epilogue | |
| 2671 _between_prologue_and_epilogue = true; | |
| 2672 // Claim locks for common data structures, then call gc_prologue_work() | |
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2673 // for each CMSGen. |
| 0 | 2674 |
| 2675 getFreelistLocks(); // gets free list locks on constituent spaces | |
| 2676 bitMapLock()->lock_without_safepoint_check(); | |
| 2677 | |
| 2678 // Should call gc_prologue_work() for all cms gens we are responsible for | |
|
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2679 bool duringMarking = _collectorState >= Marking |
| 0 | 2680 && _collectorState < Sweeping; |
|
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2681 |
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2682 // The young collections clear the modified oops state, which tells if |
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2683 // there are any modified oops in the class. The remark phase also needs |
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2684 // that information. Tell the young collection to save the union of all |
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2685 // modified klasses. |
|
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2686 if (duringMarking) { |
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2687 _ct->klass_rem_set()->set_accumulate_modified_oops(true); |
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2688 } |
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2689 |
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2690 bool registerClosure = duringMarking; |
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2691 |
|
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2692 ModUnionClosure* muc = CollectedHeap::use_parallel_gc_threads() ? |
|
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2693 &_modUnionClosurePar |
| 0 | 2694 : &_modUnionClosure; |
| 2695 _cmsGen->gc_prologue_work(full, registerClosure, muc); | |
| 2696 | |
| 2697 if (!full) { | |
| 2698 stats().record_gc0_begin(); | |
| 2699 } | |
| 2700 } | |
| 2701 | |
| 2702 void ConcurrentMarkSweepGeneration::gc_prologue(bool full) { | |
|
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2703 |
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2704 _capacity_at_prologue = capacity(); |
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2705 _used_at_prologue = used(); |
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2706 |
| 0 | 2707 // Delegate to CMScollector which knows how to coordinate between |
| 2708 // this and any other CMS generations that it is responsible for | |
| 2709 // collecting. | |
| 2710 collector()->gc_prologue(full); | |
| 2711 } | |
| 2712 | |
| 2713 // This is a "private" interface for use by this generation's CMSCollector. | |
| 2714 // Not to be called directly by any other entity (for instance, | |
| 2715 // GenCollectedHeap, which calls the "public" gc_prologue method above). | |
| 2716 void ConcurrentMarkSweepGeneration::gc_prologue_work(bool full, | |
| 2717 bool registerClosure, ModUnionClosure* modUnionClosure) { | |
| 2718 assert(!incremental_collection_failed(), "Shouldn't be set yet"); | |
| 2719 assert(cmsSpace()->preconsumptionDirtyCardClosure() == NULL, | |
| 2720 "Should be NULL"); | |
| 2721 if (registerClosure) { | |
| 2722 cmsSpace()->setPreconsumptionDirtyCardClosure(modUnionClosure); | |
| 2723 } | |
| 2724 cmsSpace()->gc_prologue(); | |
| 2725 // Clear stat counters | |
| 2726 NOT_PRODUCT( | |
| 2727 assert(_numObjectsPromoted == 0, "check"); | |
| 2728 assert(_numWordsPromoted == 0, "check"); | |
| 2729 if (Verbose && PrintGC) { | |
| 2730 gclog_or_tty->print("Allocated "SIZE_FORMAT" objects, " | |
| 2731 SIZE_FORMAT" bytes concurrently", | |
| 2732 _numObjectsAllocated, _numWordsAllocated*sizeof(HeapWord)); | |
| 2733 } | |
| 2734 _numObjectsAllocated = 0; | |
| 2735 _numWordsAllocated = 0; | |
| 2736 ) | |
| 2737 } | |
| 2738 | |
| 2739 void CMSCollector::gc_epilogue(bool full) { | |
| 2740 // The following locking discipline assumes that we are only called | |
| 2741 // when the world is stopped. | |
| 2742 assert(SafepointSynchronize::is_at_safepoint(), | |
| 2743 "world is stopped assumption"); | |
| 2744 | |
| 2745 // Currently the CMS epilogue (see CompactibleFreeListSpace) merely checks | |
| 2746 // if linear allocation blocks need to be appropriately marked to allow the | |
| 2747 // the blocks to be parsable. We also check here whether we need to nudge the | |
| 2748 // CMS collector thread to start a new cycle (if it's not already active). | |
| 2749 assert( Thread::current()->is_VM_thread() | |
| 2750 || ( CMSScavengeBeforeRemark | |
| 2751 && Thread::current()->is_ConcurrentGC_thread()), | |
| 2752 "Incorrect thread type for epilogue execution"); | |
| 2753 | |
| 2754 if (!_between_prologue_and_epilogue) { | |
| 2755 // We have already been invoked; this is a gc_epilogue delegation | |
| 2756 // from yet another CMS generation that we are responsible for, just | |
| 2757 // ignore it since all relevant work has already been done. | |
| 2758 return; | |
| 2759 } | |
| 2760 assert(haveFreelistLocks(), "must have freelist locks"); | |
| 2761 assert_lock_strong(bitMapLock()); | |
| 2762 | |
|
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2763 _ct->klass_rem_set()->set_accumulate_modified_oops(false); |
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2764 |
| 0 | 2765 _cmsGen->gc_epilogue_work(full); |
| 2766 | |
| 2767 if (_collectorState == AbortablePreclean || _collectorState == Precleaning) { | |
| 2768 // in case sampling was not already enabled, enable it | |
| 2769 _start_sampling = true; | |
| 2770 } | |
| 2771 // reset _eden_chunk_array so sampling starts afresh | |
| 2772 _eden_chunk_index = 0; | |
| 2773 | |
| 2774 size_t cms_used = _cmsGen->cmsSpace()->used(); | |
| 2775 | |
| 2776 // update performance counters - this uses a special version of | |
| 2777 // update_counters() that allows the utilization to be passed as a | |
| 2778 // parameter, avoiding multiple calls to used(). | |
| 2779 // | |
| 2780 _cmsGen->update_counters(cms_used); | |
| 2781 | |
| 2782 if (CMSIncrementalMode) { | |
| 2783 icms_update_allocation_limits(); | |
| 2784 } | |
| 2785 | |
| 2786 bitMapLock()->unlock(); | |
| 2787 releaseFreelistLocks(); | |
| 2788 | |
|
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2789 if (!CleanChunkPoolAsync) { |
|
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2790 Chunk::clean_chunk_pool(); |
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2791 } |
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2792 |
|
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|
2793 set_did_compact(false); |
| 0 | 2794 _between_prologue_and_epilogue = false; // ready for next cycle |
| 2795 } | |
| 2796 | |
| 2797 void ConcurrentMarkSweepGeneration::gc_epilogue(bool full) { | |
| 2798 collector()->gc_epilogue(full); | |
| 2799 | |
| 2800 // Also reset promotion tracking in par gc thread states. | |
|
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2801 if (CollectedHeap::use_parallel_gc_threads()) { |
| 0 | 2802 for (uint i = 0; i < ParallelGCThreads; i++) { |
|
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2803 _par_gc_thread_states[i]->promo.stopTrackingPromotions(i); |
| 0 | 2804 } |
| 2805 } | |
| 2806 } | |
| 2807 | |
| 2808 void ConcurrentMarkSweepGeneration::gc_epilogue_work(bool full) { | |
| 2809 assert(!incremental_collection_failed(), "Should have been cleared"); | |
| 2810 cmsSpace()->setPreconsumptionDirtyCardClosure(NULL); | |
| 2811 cmsSpace()->gc_epilogue(); | |
| 2812 // Print stat counters | |
| 2813 NOT_PRODUCT( | |
| 2814 assert(_numObjectsAllocated == 0, "check"); | |
| 2815 assert(_numWordsAllocated == 0, "check"); | |
| 2816 if (Verbose && PrintGC) { | |
| 2817 gclog_or_tty->print("Promoted "SIZE_FORMAT" objects, " | |
| 2818 SIZE_FORMAT" bytes", | |
| 2819 _numObjectsPromoted, _numWordsPromoted*sizeof(HeapWord)); | |
| 2820 } | |
| 2821 _numObjectsPromoted = 0; | |
| 2822 _numWordsPromoted = 0; | |
| 2823 ) | |
| 2824 | |
| 2825 if (PrintGC && Verbose) { | |
| 2826 // Call down the chain in contiguous_available needs the freelistLock | |
| 2827 // so print this out before releasing the freeListLock. | |
| 2828 gclog_or_tty->print(" Contiguous available "SIZE_FORMAT" bytes ", | |
| 2829 contiguous_available()); | |
| 2830 } | |
| 2831 } | |
| 2832 | |
| 2833 #ifndef PRODUCT | |
| 2834 bool CMSCollector::have_cms_token() { | |
| 2835 Thread* thr = Thread::current(); | |
| 2836 if (thr->is_VM_thread()) { | |
| 2837 return ConcurrentMarkSweepThread::vm_thread_has_cms_token(); | |
| 2838 } else if (thr->is_ConcurrentGC_thread()) { | |
| 2839 return ConcurrentMarkSweepThread::cms_thread_has_cms_token(); | |
| 2840 } else if (thr->is_GC_task_thread()) { | |
| 2841 return ConcurrentMarkSweepThread::vm_thread_has_cms_token() && | |
| 2842 ParGCRareEvent_lock->owned_by_self(); | |
| 2843 } | |
| 2844 return false; | |
| 2845 } | |
| 2846 #endif | |
| 2847 | |
| 2848 // Check reachability of the given heap address in CMS generation, | |
| 2849 // treating all other generations as roots. | |
| 2850 bool CMSCollector::is_cms_reachable(HeapWord* addr) { | |
| 2851 // We could "guarantee" below, rather than assert, but i'll | |
| 2852 // leave these as "asserts" so that an adventurous debugger | |
| 2853 // could try this in the product build provided some subset of | |
| 2854 // the conditions were met, provided they were intersted in the | |
| 2855 // results and knew that the computation below wouldn't interfere | |
| 2856 // with other concurrent computations mutating the structures | |
| 2857 // being read or written. | |
| 2858 assert(SafepointSynchronize::is_at_safepoint(), | |
| 2859 "Else mutations in object graph will make answer suspect"); | |
| 2860 assert(have_cms_token(), "Should hold cms token"); | |
| 2861 assert(haveFreelistLocks(), "must hold free list locks"); | |
| 2862 assert_lock_strong(bitMapLock()); | |
| 2863 | |
| 2864 // Clear the marking bit map array before starting, but, just | |
| 2865 // for kicks, first report if the given address is already marked | |
| 2866 gclog_or_tty->print_cr("Start: Address 0x%x is%s marked", addr, | |
| 2867 _markBitMap.isMarked(addr) ? "" : " not"); | |
| 2868 | |
| 2869 if (verify_after_remark()) { | |
| 2870 MutexLockerEx x(verification_mark_bm()->lock(), Mutex::_no_safepoint_check_flag); | |
| 2871 bool result = verification_mark_bm()->isMarked(addr); | |
| 2872 gclog_or_tty->print_cr("TransitiveMark: Address 0x%x %s marked", addr, | |
| 2873 result ? "IS" : "is NOT"); | |
| 2874 return result; | |
| 2875 } else { | |
| 2876 gclog_or_tty->print_cr("Could not compute result"); | |
| 2877 return false; | |
| 2878 } | |
| 2879 } | |
| 2880 | |
|
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2881 |
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|
2882 void |
|
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|
2883 CMSCollector::print_on_error(outputStream* st) { |
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2884 CMSCollector* collector = ConcurrentMarkSweepGeneration::_collector; |
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2885 if (collector != NULL) { |
|
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|
2886 CMSBitMap* bitmap = &collector->_markBitMap; |
|
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2887 st->print_cr("Marking Bits: (CMSBitMap*) " PTR_FORMAT, bitmap); |
|
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|
2888 bitmap->print_on_error(st, " Bits: "); |
|
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|
2889 |
|
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|
2890 st->cr(); |
|
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|
2891 |
|
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|
2892 CMSBitMap* mut_bitmap = &collector->_modUnionTable; |
|
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|
2893 st->print_cr("Mod Union Table: (CMSBitMap*) " PTR_FORMAT, mut_bitmap); |
|
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2894 mut_bitmap->print_on_error(st, " Bits: "); |
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|
2895 } |
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|
2896 } |
|
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|
2897 |
| 0 | 2898 //////////////////////////////////////////////////////// |
| 2899 // CMS Verification Support | |
| 2900 //////////////////////////////////////////////////////// | |
| 2901 // Following the remark phase, the following invariant | |
| 2902 // should hold -- each object in the CMS heap which is | |
| 2903 // marked in markBitMap() should be marked in the verification_mark_bm(). | |
| 2904 | |
| 2905 class VerifyMarkedClosure: public BitMapClosure { | |
| 2906 CMSBitMap* _marks; | |
| 2907 bool _failed; | |
| 2908 | |
| 2909 public: | |
| 2910 VerifyMarkedClosure(CMSBitMap* bm): _marks(bm), _failed(false) {} | |
| 2911 | |
|
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2912 bool do_bit(size_t offset) { |
| 0 | 2913 HeapWord* addr = _marks->offsetToHeapWord(offset); |
| 2914 if (!_marks->isMarked(addr)) { | |
|
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2915 oop(addr)->print_on(gclog_or_tty); |
| 0 | 2916 gclog_or_tty->print_cr(" ("INTPTR_FORMAT" should have been marked)", addr); |
| 2917 _failed = true; | |
| 2918 } | |
|
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2919 return true; |
| 0 | 2920 } |
| 2921 | |
| 2922 bool failed() { return _failed; } | |
| 2923 }; | |
| 2924 | |
|
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2925 bool CMSCollector::verify_after_remark(bool silent) { |
|
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2926 if (!silent) gclog_or_tty->print(" [Verifying CMS Marking... "); |
| 0 | 2927 MutexLockerEx ml(verification_mark_bm()->lock(), Mutex::_no_safepoint_check_flag); |
| 2928 static bool init = false; | |
| 2929 | |
| 2930 assert(SafepointSynchronize::is_at_safepoint(), | |
| 2931 "Else mutations in object graph will make answer suspect"); | |
| 2932 assert(have_cms_token(), | |
| 2933 "Else there may be mutual interference in use of " | |
| 2934 " verification data structures"); | |
| 2935 assert(_collectorState > Marking && _collectorState <= Sweeping, | |
| 2936 "Else marking info checked here may be obsolete"); | |
| 2937 assert(haveFreelistLocks(), "must hold free list locks"); | |
| 2938 assert_lock_strong(bitMapLock()); | |
| 2939 | |
| 2940 | |
| 2941 // Allocate marking bit map if not already allocated | |
| 2942 if (!init) { // first time | |
| 2943 if (!verification_mark_bm()->allocate(_span)) { | |
| 2944 return false; | |
| 2945 } | |
| 2946 init = true; | |
| 2947 } | |
| 2948 | |
| 2949 assert(verification_mark_stack()->isEmpty(), "Should be empty"); | |
| 2950 | |
| 2951 // Turn off refs discovery -- so we will be tracing through refs. | |
| 2952 // This is as intended, because by this time | |
| 2953 // GC must already have cleared any refs that need to be cleared, | |
| 2954 // and traced those that need to be marked; moreover, | |
| 2955 // the marking done here is not going to intefere in any | |
| 2956 // way with the marking information used by GC. | |
| 2957 NoRefDiscovery no_discovery(ref_processor()); | |
| 2958 | |
| 2959 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact;) | |
| 2960 | |
| 2961 // Clear any marks from a previous round | |
| 2962 verification_mark_bm()->clear_all(); | |
| 2963 assert(verification_mark_stack()->isEmpty(), "markStack should be empty"); | |
|
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2964 verify_work_stacks_empty(); |
| 0 | 2965 |
| 2966 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 2967 gch->ensure_parsability(false); // fill TLABs, but no need to retire them | |
| 2968 // Update the saved marks which may affect the root scans. | |
| 2969 gch->save_marks(); | |
| 2970 | |
| 2971 if (CMSRemarkVerifyVariant == 1) { | |
| 2972 // In this first variant of verification, we complete | |
| 2973 // all marking, then check if the new marks-verctor is | |
| 2974 // a subset of the CMS marks-vector. | |
| 2975 verify_after_remark_work_1(); | |
| 2976 } else if (CMSRemarkVerifyVariant == 2) { | |
| 2977 // In this second variant of verification, we flag an error | |
| 2978 // (i.e. an object reachable in the new marks-vector not reachable | |
| 2979 // in the CMS marks-vector) immediately, also indicating the | |
| 2980 // identify of an object (A) that references the unmarked object (B) -- | |
| 2981 // presumably, a mutation to A failed to be picked up by preclean/remark? | |
| 2982 verify_after_remark_work_2(); | |
| 2983 } else { | |
| 2984 warning("Unrecognized value %d for CMSRemarkVerifyVariant", | |
| 2985 CMSRemarkVerifyVariant); | |
| 2986 } | |
|
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2987 if (!silent) gclog_or_tty->print(" done] "); |
| 0 | 2988 return true; |
| 2989 } | |
| 2990 | |
| 2991 void CMSCollector::verify_after_remark_work_1() { | |
| 2992 ResourceMark rm; | |
| 2993 HandleMark hm; | |
| 2994 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 2995 | |
|
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2996 // Get a clear set of claim bits for the strong roots processing to work with. |
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2997 ClassLoaderDataGraph::clear_claimed_marks(); |
|
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2998 |
| 0 | 2999 // Mark from roots one level into CMS |
|
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|
3000 MarkRefsIntoClosure notOlder(_span, verification_mark_bm()); |
| 0 | 3001 gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel. |
| 3002 | |
| 3003 gch->gen_process_strong_roots(_cmsGen->level(), | |
| 3004 true, // younger gens are roots | |
|
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3005 true, // activate StrongRootsScope |
|
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3006 false, // not scavenging |
| 0 | 3007 SharedHeap::ScanningOption(roots_scanning_options()), |
|
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3008 ¬Older, |
|
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3009 true, // walk code active on stacks |
|
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3010 NULL, |
|
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|
3011 NULL); // SSS: Provide correct closure |
| 0 | 3012 |
| 3013 // Now mark from the roots | |
| 3014 MarkFromRootsClosure markFromRootsClosure(this, _span, | |
|
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3015 verification_mark_bm(), verification_mark_stack(), |
| 0 | 3016 false /* don't yield */, true /* verifying */); |
| 3017 assert(_restart_addr == NULL, "Expected pre-condition"); | |
| 3018 verification_mark_bm()->iterate(&markFromRootsClosure); | |
| 3019 while (_restart_addr != NULL) { | |
| 3020 // Deal with stack overflow: by restarting at the indicated | |
| 3021 // address. | |
| 3022 HeapWord* ra = _restart_addr; | |
| 3023 markFromRootsClosure.reset(ra); | |
| 3024 _restart_addr = NULL; | |
| 3025 verification_mark_bm()->iterate(&markFromRootsClosure, ra, _span.end()); | |
| 3026 } | |
| 3027 assert(verification_mark_stack()->isEmpty(), "Should have been drained"); | |
| 3028 verify_work_stacks_empty(); | |
| 3029 | |
| 3030 // Marking completed -- now verify that each bit marked in | |
| 3031 // verification_mark_bm() is also marked in markBitMap(); flag all | |
| 3032 // errors by printing corresponding objects. | |
| 3033 VerifyMarkedClosure vcl(markBitMap()); | |
| 3034 verification_mark_bm()->iterate(&vcl); | |
| 3035 if (vcl.failed()) { | |
| 3036 gclog_or_tty->print("Verification failed"); | |
|
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3037 Universe::heap()->print_on(gclog_or_tty); |
|
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3038 fatal("CMS: failed marking verification after remark"); |
| 0 | 3039 } |
| 3040 } | |
| 3041 | |
|
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3042 class VerifyKlassOopsKlassClosure : public KlassClosure { |
|
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3043 class VerifyKlassOopsClosure : public OopClosure { |
|
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3044 CMSBitMap* _bitmap; |
|
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3045 public: |
|
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3046 VerifyKlassOopsClosure(CMSBitMap* bitmap) : _bitmap(bitmap) { } |
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3047 void do_oop(oop* p) { guarantee(*p == NULL || _bitmap->isMarked((HeapWord*) *p), "Should be marked"); } |
|
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3048 void do_oop(narrowOop* p) { ShouldNotReachHere(); } |
|
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3049 } _oop_closure; |
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3050 public: |
|
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3051 VerifyKlassOopsKlassClosure(CMSBitMap* bitmap) : _oop_closure(bitmap) {} |
|
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3052 void do_klass(Klass* k) { |
|
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3053 k->oops_do(&_oop_closure); |
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3054 } |
|
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3055 }; |
|
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3056 |
| 0 | 3057 void CMSCollector::verify_after_remark_work_2() { |
| 3058 ResourceMark rm; | |
| 3059 HandleMark hm; | |
| 3060 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 3061 | |
|
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3062 // Get a clear set of claim bits for the strong roots processing to work with. |
|
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3063 ClassLoaderDataGraph::clear_claimed_marks(); |
|
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3064 |
| 0 | 3065 // Mark from roots one level into CMS |
| 3066 MarkRefsIntoVerifyClosure notOlder(_span, verification_mark_bm(), | |
|
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3067 markBitMap()); |
|
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3068 CMKlassClosure klass_closure(¬Older); |
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3069 |
| 0 | 3070 gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel. |
| 3071 gch->gen_process_strong_roots(_cmsGen->level(), | |
| 3072 true, // younger gens are roots | |
|
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3073 true, // activate StrongRootsScope |
|
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3074 false, // not scavenging |
| 0 | 3075 SharedHeap::ScanningOption(roots_scanning_options()), |
|
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3076 ¬Older, |
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3077 true, // walk code active on stacks |
|
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3078 NULL, |
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|
3079 &klass_closure); |
| 0 | 3080 |
| 3081 // Now mark from the roots | |
| 3082 MarkFromRootsVerifyClosure markFromRootsClosure(this, _span, | |
| 3083 verification_mark_bm(), markBitMap(), verification_mark_stack()); | |
| 3084 assert(_restart_addr == NULL, "Expected pre-condition"); | |
| 3085 verification_mark_bm()->iterate(&markFromRootsClosure); | |
| 3086 while (_restart_addr != NULL) { | |
| 3087 // Deal with stack overflow: by restarting at the indicated | |
| 3088 // address. | |
| 3089 HeapWord* ra = _restart_addr; | |
| 3090 markFromRootsClosure.reset(ra); | |
| 3091 _restart_addr = NULL; | |
| 3092 verification_mark_bm()->iterate(&markFromRootsClosure, ra, _span.end()); | |
| 3093 } | |
| 3094 assert(verification_mark_stack()->isEmpty(), "Should have been drained"); | |
| 3095 verify_work_stacks_empty(); | |
|
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3096 |
|
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|
3097 VerifyKlassOopsKlassClosure verify_klass_oops(verification_mark_bm()); |
|
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3098 ClassLoaderDataGraph::classes_do(&verify_klass_oops); |
| 0 | 3099 |
| 3100 // Marking completed -- now verify that each bit marked in | |
| 3101 // verification_mark_bm() is also marked in markBitMap(); flag all | |
| 3102 // errors by printing corresponding objects. | |
| 3103 VerifyMarkedClosure vcl(markBitMap()); | |
| 3104 verification_mark_bm()->iterate(&vcl); | |
| 3105 assert(!vcl.failed(), "Else verification above should not have succeeded"); | |
| 3106 } | |
| 3107 | |
| 3108 void ConcurrentMarkSweepGeneration::save_marks() { | |
| 3109 // delegate to CMS space | |
| 3110 cmsSpace()->save_marks(); | |
| 3111 for (uint i = 0; i < ParallelGCThreads; i++) { | |
| 3112 _par_gc_thread_states[i]->promo.startTrackingPromotions(); | |
| 3113 } | |
| 3114 } | |
| 3115 | |
| 3116 bool ConcurrentMarkSweepGeneration::no_allocs_since_save_marks() { | |
| 3117 return cmsSpace()->no_allocs_since_save_marks(); | |
| 3118 } | |
| 3119 | |
| 3120 #define CMS_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \ | |
| 3121 \ | |
| 3122 void ConcurrentMarkSweepGeneration:: \ | |
| 3123 oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) { \ | |
| 3124 cl->set_generation(this); \ | |
| 3125 cmsSpace()->oop_since_save_marks_iterate##nv_suffix(cl); \ | |
| 3126 cl->reset_generation(); \ | |
| 3127 save_marks(); \ | |
| 3128 } | |
| 3129 | |
| 3130 ALL_SINCE_SAVE_MARKS_CLOSURES(CMS_SINCE_SAVE_MARKS_DEFN) | |
| 3131 | |
| 3132 void | |
| 3133 ConcurrentMarkSweepGeneration::object_iterate_since_last_GC(ObjectClosure* blk) | |
| 3134 { | |
| 3135 // Not currently implemented; need to do the following. -- ysr. | |
| 3136 // dld -- I think that is used for some sort of allocation profiler. So it | |
| 3137 // really means the objects allocated by the mutator since the last | |
| 3138 // GC. We could potentially implement this cheaply by recording only | |
| 3139 // the direct allocations in a side data structure. | |
| 3140 // | |
| 3141 // I think we probably ought not to be required to support these | |
| 3142 // iterations at any arbitrary point; I think there ought to be some | |
| 3143 // call to enable/disable allocation profiling in a generation/space, | |
| 3144 // and the iterator ought to return the objects allocated in the | |
| 3145 // gen/space since the enable call, or the last iterator call (which | |
| 3146 // will probably be at a GC.) That way, for gens like CM&S that would | |
| 3147 // require some extra data structure to support this, we only pay the | |
| 3148 // cost when it's in use... | |
| 3149 cmsSpace()->object_iterate_since_last_GC(blk); | |
| 3150 } | |
| 3151 | |
| 3152 void | |
| 3153 ConcurrentMarkSweepGeneration::younger_refs_iterate(OopsInGenClosure* cl) { | |
| 3154 cl->set_generation(this); | |
| 3155 younger_refs_in_space_iterate(_cmsSpace, cl); | |
| 3156 cl->reset_generation(); | |
| 3157 } | |
| 3158 | |
| 3159 void | |
|
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3160 ConcurrentMarkSweepGeneration::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) { |
| 0 | 3161 if (freelistLock()->owned_by_self()) { |
| 3162 Generation::oop_iterate(mr, cl); | |
| 3163 } else { | |
| 3164 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 3165 Generation::oop_iterate(mr, cl); | |
| 3166 } | |
| 3167 } | |
| 3168 | |
| 3169 void | |
|
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|
3170 ConcurrentMarkSweepGeneration::oop_iterate(ExtendedOopClosure* cl) { |
| 0 | 3171 if (freelistLock()->owned_by_self()) { |
| 3172 Generation::oop_iterate(cl); | |
| 3173 } else { | |
| 3174 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 3175 Generation::oop_iterate(cl); | |
| 3176 } | |
| 3177 } | |
| 3178 | |
| 3179 void | |
| 3180 ConcurrentMarkSweepGeneration::object_iterate(ObjectClosure* cl) { | |
| 3181 if (freelistLock()->owned_by_self()) { | |
| 3182 Generation::object_iterate(cl); | |
| 3183 } else { | |
| 3184 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 3185 Generation::object_iterate(cl); | |
| 3186 } | |
| 3187 } | |
| 3188 | |
| 3189 void | |
|
517
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|
3190 ConcurrentMarkSweepGeneration::safe_object_iterate(ObjectClosure* cl) { |
|
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|
3191 if (freelistLock()->owned_by_self()) { |
|
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|
3192 Generation::safe_object_iterate(cl); |
|
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|
3193 } else { |
|
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|
3194 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); |
|
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|
3195 Generation::safe_object_iterate(cl); |
|
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|
3196 } |
|
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|
3197 } |
|
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|
3198 |
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|
3199 void |
| 0 | 3200 ConcurrentMarkSweepGeneration::post_compact() { |
| 3201 } | |
| 3202 | |
| 3203 void | |
| 3204 ConcurrentMarkSweepGeneration::prepare_for_verify() { | |
| 3205 // Fix the linear allocation blocks to look like free blocks. | |
| 3206 | |
| 3207 // Locks are normally acquired/released in gc_prologue/gc_epilogue, but those | |
| 3208 // are not called when the heap is verified during universe initialization and | |
| 3209 // at vm shutdown. | |
| 3210 if (freelistLock()->owned_by_self()) { | |
| 3211 cmsSpace()->prepare_for_verify(); | |
| 3212 } else { | |
| 3213 MutexLockerEx fll(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 3214 cmsSpace()->prepare_for_verify(); | |
| 3215 } | |
| 3216 } | |
| 3217 | |
| 3218 void | |
| 6008 | 3219 ConcurrentMarkSweepGeneration::verify() { |
| 0 | 3220 // Locks are normally acquired/released in gc_prologue/gc_epilogue, but those |
| 3221 // are not called when the heap is verified during universe initialization and | |
| 3222 // at vm shutdown. | |
| 3223 if (freelistLock()->owned_by_self()) { | |
| 6008 | 3224 cmsSpace()->verify(); |
| 0 | 3225 } else { |
| 3226 MutexLockerEx fll(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 6008 | 3227 cmsSpace()->verify(); |
| 3228 } | |
| 3229 } | |
| 3230 | |
| 3231 void CMSCollector::verify() { | |
| 3232 _cmsGen->verify(); | |
| 0 | 3233 } |
| 3234 | |
| 3235 #ifndef PRODUCT | |
| 3236 bool CMSCollector::overflow_list_is_empty() const { | |
| 3237 assert(_num_par_pushes >= 0, "Inconsistency"); | |
| 3238 if (_overflow_list == NULL) { | |
| 3239 assert(_num_par_pushes == 0, "Inconsistency"); | |
| 3240 } | |
| 3241 return _overflow_list == NULL; | |
| 3242 } | |
| 3243 | |
| 3244 // The methods verify_work_stacks_empty() and verify_overflow_empty() | |
| 3245 // merely consolidate assertion checks that appear to occur together frequently. | |
| 3246 void CMSCollector::verify_work_stacks_empty() const { | |
| 3247 assert(_markStack.isEmpty(), "Marking stack should be empty"); | |
| 3248 assert(overflow_list_is_empty(), "Overflow list should be empty"); | |
| 3249 } | |
| 3250 | |
| 3251 void CMSCollector::verify_overflow_empty() const { | |
| 3252 assert(overflow_list_is_empty(), "Overflow list should be empty"); | |
| 3253 assert(no_preserved_marks(), "No preserved marks"); | |
| 3254 } | |
| 3255 #endif // PRODUCT | |
| 3256 | |
|
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|
3257 // Decide if we want to enable class unloading as part of the |
|
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3258 // ensuing concurrent GC cycle. We will collect and |
|
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|
3259 // unload classes if it's the case that: |
|
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|
3260 // (1) an explicit gc request has been made and the flag |
|
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|
3261 // ExplicitGCInvokesConcurrentAndUnloadsClasses is set, OR |
|
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|
3262 // (2) (a) class unloading is enabled at the command line, and |
|
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|
3263 // (b) old gen is getting really full |
|
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|
3264 // NOTE: Provided there is no change in the state of the heap between |
|
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|
3265 // calls to this method, it should have idempotent results. Moreover, |
|
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|
3266 // its results should be monotonically increasing (i.e. going from 0 to 1, |
|
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|
3267 // but not 1 to 0) between successive calls between which the heap was |
|
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|
3268 // not collected. For the implementation below, it must thus rely on |
|
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|
3269 // the property that concurrent_cycles_since_last_unload() |
|
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|
3270 // will not decrease unless a collection cycle happened and that |
|
6725
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3271 // _cmsGen->is_too_full() are |
|
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|
3272 // themselves also monotonic in that sense. See check_monotonicity() |
|
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|
3273 // below. |
|
6725
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3274 void CMSCollector::update_should_unload_classes() { |
|
94
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|
3275 _should_unload_classes = false; |
|
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|
3276 // Condition 1 above |
|
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|
3277 if (_full_gc_requested && ExplicitGCInvokesConcurrentAndUnloadsClasses) { |
|
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|
3278 _should_unload_classes = true; |
|
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|
3279 } else if (CMSClassUnloadingEnabled) { // Condition 2.a above |
|
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|
3280 // Disjuncts 2.b.(i,ii,iii) above |
|
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|
3281 _should_unload_classes = (concurrent_cycles_since_last_unload() >= |
|
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|
3282 CMSClassUnloadingMaxInterval) |
|
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|
3283 || _cmsGen->is_too_full(); |
|
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|
3284 } |
|
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|
3285 } |
|
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|
3286 |
|
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|
3287 bool ConcurrentMarkSweepGeneration::is_too_full() const { |
|
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|
3288 bool res = should_concurrent_collect(); |
|
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|
3289 res = res && (occupancy() > (double)CMSIsTooFullPercentage/100.0); |
|
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|
3290 return res; |
|
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|
3291 } |
|
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3292 |
| 0 | 3293 void CMSCollector::setup_cms_unloading_and_verification_state() { |
|
3293
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|
3294 const bool should_verify = VerifyBeforeGC || VerifyAfterGC || VerifyDuringGC |
| 0 | 3295 || VerifyBeforeExit; |
|
3293
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|
3296 const int rso = SharedHeap::SO_Strings | SharedHeap::SO_CodeCache; |
| 0 | 3297 |
|
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|
3298 if (should_unload_classes()) { // Should unload classes this cycle |
| 0 | 3299 remove_root_scanning_option(rso); // Shrink the root set appropriately |
| 3300 set_verifying(should_verify); // Set verification state for this cycle | |
| 3301 return; // Nothing else needs to be done at this time | |
| 3302 } | |
| 3303 | |
| 3304 // Not unloading classes this cycle | |
|
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|
3305 assert(!should_unload_classes(), "Inconsitency!"); |
|
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|
3306 if ((!verifying() || unloaded_classes_last_cycle()) && should_verify) { |
| 0 | 3307 // Include symbols, strings and code cache elements to prevent their resurrection. |
| 3308 add_root_scanning_option(rso); | |
| 3309 set_verifying(true); | |
| 3310 } else if (verifying() && !should_verify) { | |
| 3311 // We were verifying, but some verification flags got disabled. | |
| 3312 set_verifying(false); | |
| 3313 // Exclude symbols, strings and code cache elements from root scanning to | |
| 3314 // reduce IM and RM pauses. | |
| 3315 remove_root_scanning_option(rso); | |
| 3316 } | |
| 3317 } | |
| 3318 | |
| 3319 | |
| 3320 #ifndef PRODUCT | |
| 3321 HeapWord* CMSCollector::block_start(const void* p) const { | |
| 3322 const HeapWord* addr = (HeapWord*)p; | |
| 3323 if (_span.contains(p)) { | |
| 3324 if (_cmsGen->cmsSpace()->is_in_reserved(addr)) { | |
| 3325 return _cmsGen->cmsSpace()->block_start(p); | |
| 3326 } | |
| 3327 } | |
| 3328 return NULL; | |
| 3329 } | |
| 3330 #endif | |
| 3331 | |
| 3332 HeapWord* | |
| 3333 ConcurrentMarkSweepGeneration::expand_and_allocate(size_t word_size, | |
| 3334 bool tlab, | |
| 3335 bool parallel) { | |
|
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|
3336 CMSSynchronousYieldRequest yr; |
| 0 | 3337 assert(!tlab, "Can't deal with TLAB allocation"); |
| 3338 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 3339 expand(word_size*HeapWordSize, MinHeapDeltaBytes, | |
| 3340 CMSExpansionCause::_satisfy_allocation); | |
| 3341 if (GCExpandToAllocateDelayMillis > 0) { | |
| 3342 os::sleep(Thread::current(), GCExpandToAllocateDelayMillis, false); | |
| 3343 } | |
|
9
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|
3344 return have_lock_and_allocate(word_size, tlab); |
| 0 | 3345 } |
| 3346 | |
| 3347 // YSR: All of this generation expansion/shrinking stuff is an exact copy of | |
| 3348 // OneContigSpaceCardGeneration, which makes me wonder if we should move this | |
| 3349 // to CardGeneration and share it... | |
|
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3350 bool ConcurrentMarkSweepGeneration::expand(size_t bytes, size_t expand_bytes) { |
|
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3351 return CardGeneration::expand(bytes, expand_bytes); |
|
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|
3352 } |
|
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|
3353 |
| 0 | 3354 void ConcurrentMarkSweepGeneration::expand(size_t bytes, size_t expand_bytes, |
| 3355 CMSExpansionCause::Cause cause) | |
| 3356 { | |
|
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|
3357 |
|
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|
3358 bool success = expand(bytes, expand_bytes); |
|
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3359 |
| 0 | 3360 // remember why we expanded; this information is used |
| 3361 // by shouldConcurrentCollect() when making decisions on whether to start | |
| 3362 // a new CMS cycle. | |
| 3363 if (success) { | |
| 3364 set_expansion_cause(cause); | |
| 3365 if (PrintGCDetails && Verbose) { | |
| 3366 gclog_or_tty->print_cr("Expanded CMS gen for %s", | |
| 3367 CMSExpansionCause::to_string(cause)); | |
| 3368 } | |
| 3369 } | |
| 3370 } | |
| 3371 | |
| 3372 HeapWord* ConcurrentMarkSweepGeneration::expand_and_par_lab_allocate(CMSParGCThreadState* ps, size_t word_sz) { | |
| 3373 HeapWord* res = NULL; | |
| 3374 MutexLocker x(ParGCRareEvent_lock); | |
| 3375 while (true) { | |
| 3376 // Expansion by some other thread might make alloc OK now: | |
| 3377 res = ps->lab.alloc(word_sz); | |
| 3378 if (res != NULL) return res; | |
| 3379 // If there's not enough expansion space available, give up. | |
| 3380 if (_virtual_space.uncommitted_size() < (word_sz * HeapWordSize)) { | |
| 3381 return NULL; | |
| 3382 } | |
| 3383 // Otherwise, we try expansion. | |
| 3384 expand(word_sz*HeapWordSize, MinHeapDeltaBytes, | |
| 3385 CMSExpansionCause::_allocate_par_lab); | |
| 3386 // Now go around the loop and try alloc again; | |
| 3387 // A competing par_promote might beat us to the expansion space, | |
| 3388 // so we may go around the loop again if promotion fails agaion. | |
| 3389 if (GCExpandToAllocateDelayMillis > 0) { | |
| 3390 os::sleep(Thread::current(), GCExpandToAllocateDelayMillis, false); | |
| 3391 } | |
| 3392 } | |
| 3393 } | |
| 3394 | |
| 3395 | |
| 3396 bool ConcurrentMarkSweepGeneration::expand_and_ensure_spooling_space( | |
| 3397 PromotionInfo* promo) { | |
| 3398 MutexLocker x(ParGCRareEvent_lock); | |
| 3399 size_t refill_size_bytes = promo->refillSize() * HeapWordSize; | |
| 3400 while (true) { | |
| 3401 // Expansion by some other thread might make alloc OK now: | |
| 3402 if (promo->ensure_spooling_space()) { | |
| 3403 assert(promo->has_spooling_space(), | |
| 3404 "Post-condition of successful ensure_spooling_space()"); | |
| 3405 return true; | |
| 3406 } | |
| 3407 // If there's not enough expansion space available, give up. | |
| 3408 if (_virtual_space.uncommitted_size() < refill_size_bytes) { | |
| 3409 return false; | |
| 3410 } | |
| 3411 // Otherwise, we try expansion. | |
| 3412 expand(refill_size_bytes, MinHeapDeltaBytes, | |
| 3413 CMSExpansionCause::_allocate_par_spooling_space); | |
| 3414 // Now go around the loop and try alloc again; | |
| 3415 // A competing allocation might beat us to the expansion space, | |
| 3416 // so we may go around the loop again if allocation fails again. | |
| 3417 if (GCExpandToAllocateDelayMillis > 0) { | |
| 3418 os::sleep(Thread::current(), GCExpandToAllocateDelayMillis, false); | |
| 3419 } | |
| 3420 } | |
| 3421 } | |
| 3422 | |
| 3423 | |
|
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|
3424 void ConcurrentMarkSweepGeneration::shrink_by(size_t bytes) { |
|
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|
3425 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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|
3426 // Shrink committed space |
|
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|
3427 _virtual_space.shrink_by(bytes); |
|
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|
3428 // Shrink space; this also shrinks the space's BOT |
|
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|
3429 _cmsSpace->set_end((HeapWord*) _virtual_space.high()); |
|
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|
3430 size_t new_word_size = heap_word_size(_cmsSpace->capacity()); |
|
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8008508: CMS does not correctly reduce heap size after a Full GC
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|
3431 // Shrink the shared block offset array |
|
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|
3432 _bts->resize(new_word_size); |
|
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|
3433 MemRegion mr(_cmsSpace->bottom(), new_word_size); |
|
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8008508: CMS does not correctly reduce heap size after a Full GC
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|
3434 // Shrink the card table |
|
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changeset
|
3435 Universe::heap()->barrier_set()->resize_covered_region(mr); |
|
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|
3436 |
|
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|
3437 if (Verbose && PrintGC) { |
|
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8008508: CMS does not correctly reduce heap size after a Full GC
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|
3438 size_t new_mem_size = _virtual_space.committed_size(); |
|
8617e38bb4cb
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|
3439 size_t old_mem_size = new_mem_size + bytes; |
|
8617e38bb4cb
8008508: CMS does not correctly reduce heap size after a Full GC
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|
3440 gclog_or_tty->print_cr("Shrinking %s from " SIZE_FORMAT "K to " SIZE_FORMAT "K", |
|
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|
3441 name(), old_mem_size/K, new_mem_size/K); |
|
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8008508: CMS does not correctly reduce heap size after a Full GC
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|
3442 } |
|
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|
3443 } |
| 0 | 3444 |
| 3445 void ConcurrentMarkSweepGeneration::shrink(size_t bytes) { | |
| 3446 assert_locked_or_safepoint(Heap_lock); | |
| 3447 size_t size = ReservedSpace::page_align_size_down(bytes); | |
| 3448 if (size > 0) { | |
| 3449 shrink_by(size); | |
| 3450 } | |
| 3451 } | |
| 3452 | |
| 3453 bool ConcurrentMarkSweepGeneration::grow_by(size_t bytes) { | |
| 3454 assert_locked_or_safepoint(Heap_lock); | |
| 3455 bool result = _virtual_space.expand_by(bytes); | |
| 3456 if (result) { | |
| 3457 size_t new_word_size = | |
| 3458 heap_word_size(_virtual_space.committed_size()); | |
| 3459 MemRegion mr(_cmsSpace->bottom(), new_word_size); | |
| 3460 _bts->resize(new_word_size); // resize the block offset shared array | |
| 3461 Universe::heap()->barrier_set()->resize_covered_region(mr); | |
| 3462 // Hmmmm... why doesn't CFLS::set_end verify locking? | |
| 3463 // This is quite ugly; FIX ME XXX | |
|
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|
3464 _cmsSpace->assert_locked(freelistLock()); |
| 0 | 3465 _cmsSpace->set_end((HeapWord*)_virtual_space.high()); |
| 3466 | |
| 3467 // update the space and generation capacity counters | |
| 3468 if (UsePerfData) { | |
| 3469 _space_counters->update_capacity(); | |
| 3470 _gen_counters->update_all(); | |
| 3471 } | |
| 3472 | |
| 3473 if (Verbose && PrintGC) { | |
| 3474 size_t new_mem_size = _virtual_space.committed_size(); | |
| 3475 size_t old_mem_size = new_mem_size - bytes; | |
|
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|
3476 gclog_or_tty->print_cr("Expanding %s from " SIZE_FORMAT "K by " SIZE_FORMAT "K to " SIZE_FORMAT "K", |
| 0 | 3477 name(), old_mem_size/K, bytes/K, new_mem_size/K); |
| 3478 } | |
| 3479 } | |
| 3480 return result; | |
| 3481 } | |
| 3482 | |
| 3483 bool ConcurrentMarkSweepGeneration::grow_to_reserved() { | |
| 3484 assert_locked_or_safepoint(Heap_lock); | |
| 3485 bool success = true; | |
| 3486 const size_t remaining_bytes = _virtual_space.uncommitted_size(); | |
| 3487 if (remaining_bytes > 0) { | |
| 3488 success = grow_by(remaining_bytes); | |
| 3489 DEBUG_ONLY(if (!success) warning("grow to reserved failed");) | |
| 3490 } | |
| 3491 return success; | |
| 3492 } | |
| 3493 | |
|
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|
3494 void ConcurrentMarkSweepGeneration::shrink_free_list_by(size_t bytes) { |
| 0 | 3495 assert_locked_or_safepoint(Heap_lock); |
| 3496 assert_lock_strong(freelistLock()); | |
|
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|
3497 if (PrintGCDetails && Verbose) { |
|
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|
3498 warning("Shrinking of CMS not yet implemented"); |
|
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|
3499 } |
| 0 | 3500 return; |
| 3501 } | |
| 3502 | |
| 3503 | |
| 3504 // Simple ctor/dtor wrapper for accounting & timer chores around concurrent | |
| 3505 // phases. | |
| 3506 class CMSPhaseAccounting: public StackObj { | |
| 3507 public: | |
| 3508 CMSPhaseAccounting(CMSCollector *collector, | |
| 3509 const char *phase, | |
| 3510 bool print_cr = true); | |
| 3511 ~CMSPhaseAccounting(); | |
| 3512 | |
| 3513 private: | |
| 3514 CMSCollector *_collector; | |
| 3515 const char *_phase; | |
| 3516 elapsedTimer _wallclock; | |
| 3517 bool _print_cr; | |
| 3518 | |
| 3519 public: | |
| 3520 // Not MT-safe; so do not pass around these StackObj's | |
| 3521 // where they may be accessed by other threads. | |
| 3522 jlong wallclock_millis() { | |
| 3523 assert(_wallclock.is_active(), "Wall clock should not stop"); | |
| 3524 _wallclock.stop(); // to record time | |
| 3525 jlong ret = _wallclock.milliseconds(); | |
| 3526 _wallclock.start(); // restart | |
| 3527 return ret; | |
| 3528 } | |
| 3529 }; | |
| 3530 | |
| 3531 CMSPhaseAccounting::CMSPhaseAccounting(CMSCollector *collector, | |
| 3532 const char *phase, | |
| 3533 bool print_cr) : | |
| 3534 _collector(collector), _phase(phase), _print_cr(print_cr) { | |
| 3535 | |
| 3536 if (PrintCMSStatistics != 0) { | |
| 3537 _collector->resetYields(); | |
| 3538 } | |
|
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8008684: CMS: concurrent phase start markers should always be printed
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diff
changeset
|
3539 if (PrintGCDetails) { |
| 0 | 3540 gclog_or_tty->date_stamp(PrintGCDateStamps); |
|
8740
62609ffa2fc6
8008684: CMS: concurrent phase start markers should always be printed
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diff
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|
3541 gclog_or_tty->stamp(PrintGCTimeStamps); |
|
62609ffa2fc6
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diff
changeset
|
3542 gclog_or_tty->print_cr("[%s-concurrent-%s-start]", |
| 0 | 3543 _collector->cmsGen()->short_name(), _phase); |
| 3544 } | |
| 3545 _collector->resetTimer(); | |
| 3546 _wallclock.start(); | |
| 3547 _collector->startTimer(); | |
| 3548 } | |
| 3549 | |
| 3550 CMSPhaseAccounting::~CMSPhaseAccounting() { | |
| 3551 assert(_wallclock.is_active(), "Wall clock should not have stopped"); | |
| 3552 _collector->stopTimer(); | |
| 3553 _wallclock.stop(); | |
| 3554 if (PrintGCDetails) { | |
| 3555 gclog_or_tty->date_stamp(PrintGCDateStamps); | |
|
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|
3556 gclog_or_tty->stamp(PrintGCTimeStamps); |
| 0 | 3557 gclog_or_tty->print("[%s-concurrent-%s: %3.3f/%3.3f secs]", |
| 3558 _collector->cmsGen()->short_name(), | |
| 3559 _phase, _collector->timerValue(), _wallclock.seconds()); | |
| 3560 if (_print_cr) { | |
| 3561 gclog_or_tty->print_cr(""); | |
| 3562 } | |
| 3563 if (PrintCMSStatistics != 0) { | |
| 3564 gclog_or_tty->print_cr(" (CMS-concurrent-%s yielded %d times)", _phase, | |
| 3565 _collector->yields()); | |
| 3566 } | |
| 3567 } | |
| 3568 } | |
| 3569 | |
| 3570 // CMS work | |
| 3571 | |
| 3572 // Checkpoint the roots into this generation from outside | |
| 3573 // this generation. [Note this initial checkpoint need only | |
| 3574 // be approximate -- we'll do a catch up phase subsequently.] | |
| 3575 void CMSCollector::checkpointRootsInitial(bool asynch) { | |
| 3576 assert(_collectorState == InitialMarking, "Wrong collector state"); | |
| 3577 check_correct_thread_executing(); | |
|
3356
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|
3578 TraceCMSMemoryManagerStats tms(_collectorState,GenCollectedHeap::heap()->gc_cause()); |
|
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|
3579 |
| 10405 | 3580 save_heap_summary(); |
| 3581 report_heap_summary(GCWhen::BeforeGC); | |
| 3582 | |
| 0 | 3583 ReferenceProcessor* rp = ref_processor(); |
| 3584 SpecializationStats::clear(); | |
| 3585 assert(_restart_addr == NULL, "Control point invariant"); | |
| 3586 if (asynch) { | |
| 3587 // acquire locks for subsequent manipulations | |
| 3588 MutexLockerEx x(bitMapLock(), | |
| 3589 Mutex::_no_safepoint_check_flag); | |
| 3590 checkpointRootsInitialWork(asynch); | |
|
3979
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|
3591 // enable ("weak") refs discovery |
|
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|
3592 rp->enable_discovery(true /*verify_disabled*/, true /*check_no_refs*/); |
| 0 | 3593 _collectorState = Marking; |
| 3594 } else { | |
| 3595 // (Weak) Refs discovery: this is controlled from genCollectedHeap::do_collection | |
| 3596 // which recognizes if we are a CMS generation, and doesn't try to turn on | |
| 3597 // discovery; verify that they aren't meddling. | |
| 3598 assert(!rp->discovery_is_atomic(), | |
| 3599 "incorrect setting of discovery predicate"); | |
| 3600 assert(!rp->discovery_enabled(), "genCollectedHeap shouldn't control " | |
| 3601 "ref discovery for this generation kind"); | |
| 3602 // already have locks | |
| 3603 checkpointRootsInitialWork(asynch); | |
|
3979
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|
3604 // now enable ("weak") refs discovery |
|
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|
3605 rp->enable_discovery(true /*verify_disabled*/, false /*verify_no_refs*/); |
| 0 | 3606 _collectorState = Marking; |
| 3607 } | |
| 3608 SpecializationStats::print(); | |
| 3609 } | |
| 3610 | |
| 3611 void CMSCollector::checkpointRootsInitialWork(bool asynch) { | |
| 3612 assert(SafepointSynchronize::is_at_safepoint(), "world should be stopped"); | |
| 3613 assert(_collectorState == InitialMarking, "just checking"); | |
| 3614 | |
| 3615 // If there has not been a GC[n-1] since last GC[n] cycle completed, | |
| 3616 // precede our marking with a collection of all | |
| 3617 // younger generations to keep floating garbage to a minimum. | |
| 3618 // XXX: we won't do this for now -- it's an optimization to be done later. | |
| 3619 | |
| 3620 // already have locks | |
| 3621 assert_lock_strong(bitMapLock()); | |
| 3622 assert(_markBitMap.isAllClear(), "was reset at end of previous cycle"); | |
| 3623 | |
| 3624 // Setup the verification and class unloading state for this | |
| 3625 // CMS collection cycle. | |
| 3626 setup_cms_unloading_and_verification_state(); | |
| 3627 | |
| 10405 | 3628 NOT_PRODUCT(GCTraceTime t("\ncheckpointRootsInitialWork", |
| 3629 PrintGCDetails && Verbose, true, _gc_timer_cm);) | |
| 0 | 3630 if (UseAdaptiveSizePolicy) { |
| 3631 size_policy()->checkpoint_roots_initial_begin(); | |
| 3632 } | |
| 3633 | |
| 3634 // Reset all the PLAB chunk arrays if necessary. | |
| 3635 if (_survivor_plab_array != NULL && !CMSPLABRecordAlways) { | |
| 3636 reset_survivor_plab_arrays(); | |
| 3637 } | |
| 3638 | |
| 3639 ResourceMark rm; | |
| 3640 HandleMark hm; | |
| 3641 | |
| 3642 FalseClosure falseClosure; | |
| 3643 // In the case of a synchronous collection, we will elide the | |
| 3644 // remark step, so it's important to catch all the nmethod oops | |
|
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|
3645 // in this step. |
|
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|
3646 // The final 'true' flag to gen_process_strong_roots will ensure this. |
|
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|
3647 // If 'async' is true, we can relax the nmethod tracing. |
|
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|
3648 MarkRefsIntoClosure notOlder(_span, &_markBitMap); |
| 0 | 3649 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
| 3650 | |
| 3651 verify_work_stacks_empty(); | |
| 3652 verify_overflow_empty(); | |
| 3653 | |
| 3654 gch->ensure_parsability(false); // fill TLABs, but no need to retire them | |
| 3655 // Update the saved marks which may affect the root scans. | |
| 3656 gch->save_marks(); | |
| 3657 | |
| 3658 // weak reference processing has not started yet. | |
| 3659 ref_processor()->set_enqueuing_is_done(false); | |
| 3660 | |
|
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|
3661 // Need to remember all newly created CLDs, |
|
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|
3662 // so that we can guarantee that the remark finds them. |
|
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|
3663 ClassLoaderDataGraph::remember_new_clds(true); |
|
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|
3664 |
|
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|
3665 // Whenever a CLD is found, it will be claimed before proceeding to mark |
|
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|
3666 // the klasses. The claimed marks need to be cleared before marking starts. |
|
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|
3667 ClassLoaderDataGraph::clear_claimed_marks(); |
|
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|
3668 |
|
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|
3669 CMKlassClosure klass_closure(¬Older); |
| 0 | 3670 { |
| 3671 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact;) | |
| 3672 gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel. | |
| 3673 gch->gen_process_strong_roots(_cmsGen->level(), | |
| 3674 true, // younger gens are roots | |
|
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|
3675 true, // activate StrongRootsScope |
|
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|
3676 false, // not scavenging |
| 0 | 3677 SharedHeap::ScanningOption(roots_scanning_options()), |
|
989
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diff
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|
3678 ¬Older, |
|
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diff
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|
3679 true, // walk all of code cache if (so & SO_CodeCache) |
|
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|
3680 NULL, |
|
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|
3681 &klass_closure); |
| 0 | 3682 } |
| 3683 | |
| 3684 // Clear mod-union table; it will be dirtied in the prologue of | |
| 3685 // CMS generation per each younger generation collection. | |
| 3686 | |
| 3687 assert(_modUnionTable.isAllClear(), | |
| 3688 "Was cleared in most recent final checkpoint phase" | |
| 3689 " or no bits are set in the gc_prologue before the start of the next " | |
| 3690 "subsequent marking phase."); | |
| 3691 | |
|
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|
3692 assert(_ct->klass_rem_set()->mod_union_is_clear(), "Must be"); |
|
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|
3693 |
| 0 | 3694 // Save the end of the used_region of the constituent generations |
| 3695 // to be used to limit the extent of sweep in each generation. | |
| 3696 save_sweep_limits(); | |
| 3697 if (UseAdaptiveSizePolicy) { | |
| 3698 size_policy()->checkpoint_roots_initial_end(gch->gc_cause()); | |
| 3699 } | |
| 3700 verify_overflow_empty(); | |
| 3701 } | |
| 3702 | |
| 3703 bool CMSCollector::markFromRoots(bool asynch) { | |
| 3704 // we might be tempted to assert that: | |
| 3705 // assert(asynch == !SafepointSynchronize::is_at_safepoint(), | |
| 3706 // "inconsistent argument?"); | |
| 3707 // However that wouldn't be right, because it's possible that | |
| 3708 // a safepoint is indeed in progress as a younger generation | |
| 3709 // stop-the-world GC happens even as we mark in this generation. | |
| 3710 assert(_collectorState == Marking, "inconsistent state?"); | |
| 3711 check_correct_thread_executing(); | |
| 3712 verify_overflow_empty(); | |
| 3713 | |
| 3714 bool res; | |
| 3715 if (asynch) { | |
| 3716 | |
| 3717 // Start the timers for adaptive size policy for the concurrent phases | |
| 3718 // Do it here so that the foreground MS can use the concurrent | |
| 3719 // timer since a foreground MS might has the sweep done concurrently | |
| 3720 // or STW. | |
| 3721 if (UseAdaptiveSizePolicy) { | |
| 3722 size_policy()->concurrent_marking_begin(); | |
| 3723 } | |
| 3724 | |
| 3725 // Weak ref discovery note: We may be discovering weak | |
| 3726 // refs in this generation concurrent (but interleaved) with | |
| 3727 // weak ref discovery by a younger generation collector. | |
| 3728 | |
| 3729 CMSTokenSyncWithLocks ts(true, bitMapLock()); | |
| 3730 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
| 3731 CMSPhaseAccounting pa(this, "mark", !PrintGCDetails); | |
| 3732 res = markFromRootsWork(asynch); | |
| 3733 if (res) { | |
| 3734 _collectorState = Precleaning; | |
| 3735 } else { // We failed and a foreground collection wants to take over | |
| 3736 assert(_foregroundGCIsActive, "internal state inconsistency"); | |
| 3737 assert(_restart_addr == NULL, "foreground will restart from scratch"); | |
| 3738 if (PrintGCDetails) { | |
| 3739 gclog_or_tty->print_cr("bailing out to foreground collection"); | |
| 3740 } | |
| 3741 } | |
| 3742 if (UseAdaptiveSizePolicy) { | |
| 3743 size_policy()->concurrent_marking_end(); | |
| 3744 } | |
| 3745 } else { | |
| 3746 assert(SafepointSynchronize::is_at_safepoint(), | |
| 3747 "inconsistent with asynch == false"); | |
| 3748 if (UseAdaptiveSizePolicy) { | |
| 3749 size_policy()->ms_collection_marking_begin(); | |
| 3750 } | |
| 3751 // already have locks | |
| 3752 res = markFromRootsWork(asynch); | |
| 3753 _collectorState = FinalMarking; | |
| 3754 if (UseAdaptiveSizePolicy) { | |
| 3755 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 3756 size_policy()->ms_collection_marking_end(gch->gc_cause()); | |
| 3757 } | |
| 3758 } | |
| 3759 verify_overflow_empty(); | |
| 3760 return res; | |
| 3761 } | |
| 3762 | |
| 3763 bool CMSCollector::markFromRootsWork(bool asynch) { | |
| 3764 // iterate over marked bits in bit map, doing a full scan and mark | |
| 3765 // from these roots using the following algorithm: | |
| 3766 // . if oop is to the right of the current scan pointer, | |
| 3767 // mark corresponding bit (we'll process it later) | |
| 3768 // . else (oop is to left of current scan pointer) | |
| 3769 // push oop on marking stack | |
| 3770 // . drain the marking stack | |
| 3771 | |
| 3772 // Note that when we do a marking step we need to hold the | |
| 3773 // bit map lock -- recall that direct allocation (by mutators) | |
| 3774 // and promotion (by younger generation collectors) is also | |
| 3775 // marking the bit map. [the so-called allocate live policy.] | |
| 3776 // Because the implementation of bit map marking is not | |
| 3777 // robust wrt simultaneous marking of bits in the same word, | |
| 3778 // we need to make sure that there is no such interference | |
| 3779 // between concurrent such updates. | |
| 3780 | |
| 3781 // already have locks | |
| 3782 assert_lock_strong(bitMapLock()); | |
| 3783 | |
| 3784 verify_work_stacks_empty(); | |
| 3785 verify_overflow_empty(); | |
| 3786 bool result = false; | |
| 1284 | 3787 if (CMSConcurrentMTEnabled && ConcGCThreads > 0) { |
| 0 | 3788 result = do_marking_mt(asynch); |
| 3789 } else { | |
| 3790 result = do_marking_st(asynch); | |
| 3791 } | |
| 3792 return result; | |
| 3793 } | |
| 3794 | |
| 3795 // Forward decl | |
| 3796 class CMSConcMarkingTask; | |
| 3797 | |
| 3798 class CMSConcMarkingTerminator: public ParallelTaskTerminator { | |
| 3799 CMSCollector* _collector; | |
| 3800 CMSConcMarkingTask* _task; | |
|
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|
3801 public: |
| 0 | 3802 virtual void yield(); |
|
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|
3803 |
| 0 | 3804 // "n_threads" is the number of threads to be terminated. |
| 3805 // "queue_set" is a set of work queues of other threads. | |
| 3806 // "collector" is the CMS collector associated with this task terminator. | |
| 3807 // "yield" indicates whether we need the gang as a whole to yield. | |
|
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|
3808 CMSConcMarkingTerminator(int n_threads, TaskQueueSetSuper* queue_set, CMSCollector* collector) : |
| 0 | 3809 ParallelTaskTerminator(n_threads, queue_set), |
|
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|
3810 _collector(collector) { } |
|
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|
3811 |
|
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|
3812 void set_task(CMSConcMarkingTask* task) { |
|
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|
3813 _task = task; |
|
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|
3814 } |
|
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|
3815 }; |
|
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|
3816 |
|
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|
3817 class CMSConcMarkingTerminatorTerminator: public TerminatorTerminator { |
|
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|
3818 CMSConcMarkingTask* _task; |
|
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|
3819 public: |
|
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|
3820 bool should_exit_termination(); |
| 0 | 3821 void set_task(CMSConcMarkingTask* task) { |
| 3822 _task = task; | |
| 3823 } | |
| 3824 }; | |
| 3825 | |
| 3826 // MT Concurrent Marking Task | |
| 3827 class CMSConcMarkingTask: public YieldingFlexibleGangTask { | |
| 3828 CMSCollector* _collector; | |
| 3829 int _n_workers; // requested/desired # workers | |
| 3830 bool _asynch; | |
| 3831 bool _result; | |
| 3832 CompactibleFreeListSpace* _cms_space; | |
|
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|
3833 char _pad_front[64]; // padding to ... |
|
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|
3834 HeapWord* _global_finger; // ... avoid sharing cache line |
|
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|
3835 char _pad_back[64]; |
|
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|
3836 HeapWord* _restart_addr; |
| 0 | 3837 |
| 3838 // Exposed here for yielding support | |
| 3839 Mutex* const _bit_map_lock; | |
| 3840 | |
| 3841 // The per thread work queues, available here for stealing | |
| 3842 OopTaskQueueSet* _task_queues; | |
|
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|
3843 |
|
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|
3844 // Termination (and yielding) support |
| 0 | 3845 CMSConcMarkingTerminator _term; |
|
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|
3846 CMSConcMarkingTerminatorTerminator _term_term; |
| 0 | 3847 |
| 3848 public: | |
| 3849 CMSConcMarkingTask(CMSCollector* collector, | |
| 3850 CompactibleFreeListSpace* cms_space, | |
|
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|
3851 bool asynch, |
| 0 | 3852 YieldingFlexibleWorkGang* workers, |
| 3853 OopTaskQueueSet* task_queues): | |
| 3854 YieldingFlexibleGangTask("Concurrent marking done multi-threaded"), | |
| 3855 _collector(collector), | |
| 3856 _cms_space(cms_space), | |
|
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|
3857 _asynch(asynch), _n_workers(0), _result(true), |
|
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|
3858 _task_queues(task_queues), |
|
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|
3859 _term(_n_workers, task_queues, _collector), |
| 0 | 3860 _bit_map_lock(collector->bitMapLock()) |
| 3861 { | |
|
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3862 _requested_size = _n_workers; |
| 0 | 3863 _term.set_task(this); |
|
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3864 _term_term.set_task(this); |
|
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3865 _restart_addr = _global_finger = _cms_space->bottom(); |
| 0 | 3866 } |
| 3867 | |
| 3868 | |
| 3869 OopTaskQueueSet* task_queues() { return _task_queues; } | |
| 3870 | |
| 3871 OopTaskQueue* work_queue(int i) { return task_queues()->queue(i); } | |
| 3872 | |
| 3873 HeapWord** global_finger_addr() { return &_global_finger; } | |
| 3874 | |
| 3875 CMSConcMarkingTerminator* terminator() { return &_term; } | |
| 3876 | |
|
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3877 virtual void set_for_termination(int active_workers) { |
|
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3878 terminator()->reset_for_reuse(active_workers); |
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3879 } |
|
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3880 |
|
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3881 void work(uint worker_id); |
|
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3882 bool should_yield() { |
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3883 return ConcurrentMarkSweepThread::should_yield() |
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3884 && !_collector->foregroundGCIsActive() |
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3885 && _asynch; |
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3886 } |
| 0 | 3887 |
| 3888 virtual void coordinator_yield(); // stuff done by coordinator | |
| 3889 bool result() { return _result; } | |
| 3890 | |
| 3891 void reset(HeapWord* ra) { | |
|
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3892 assert(_global_finger >= _cms_space->end(), "Postcondition of ::work(i)"); |
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3893 _restart_addr = _global_finger = ra; |
| 0 | 3894 _term.reset_for_reuse(); |
| 3895 } | |
| 3896 | |
| 3897 static bool get_work_from_overflow_stack(CMSMarkStack* ovflw_stk, | |
| 3898 OopTaskQueue* work_q); | |
| 3899 | |
| 3900 private: | |
| 3901 void do_scan_and_mark(int i, CompactibleFreeListSpace* sp); | |
| 3902 void do_work_steal(int i); | |
| 3903 void bump_global_finger(HeapWord* f); | |
| 3904 }; | |
| 3905 | |
|
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3906 bool CMSConcMarkingTerminatorTerminator::should_exit_termination() { |
|
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3907 assert(_task != NULL, "Error"); |
|
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3908 return _task->yielding(); |
|
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3909 // Note that we do not need the disjunct || _task->should_yield() above |
|
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3910 // because we want terminating threads to yield only if the task |
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3911 // is already in the midst of yielding, which happens only after at least one |
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3912 // thread has yielded. |
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3913 } |
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3914 |
| 0 | 3915 void CMSConcMarkingTerminator::yield() { |
|
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3916 if (_task->should_yield()) { |
| 0 | 3917 _task->yield(); |
| 3918 } else { | |
| 3919 ParallelTaskTerminator::yield(); | |
| 3920 } | |
| 3921 } | |
| 3922 | |
| 3923 //////////////////////////////////////////////////////////////// | |
| 3924 // Concurrent Marking Algorithm Sketch | |
| 3925 //////////////////////////////////////////////////////////////// | |
| 3926 // Until all tasks exhausted (both spaces): | |
| 3927 // -- claim next available chunk | |
| 3928 // -- bump global finger via CAS | |
| 3929 // -- find first object that starts in this chunk | |
| 3930 // and start scanning bitmap from that position | |
| 3931 // -- scan marked objects for oops | |
| 3932 // -- CAS-mark target, and if successful: | |
| 3933 // . if target oop is above global finger (volatile read) | |
| 3934 // nothing to do | |
| 3935 // . if target oop is in chunk and above local finger | |
| 3936 // then nothing to do | |
| 3937 // . else push on work-queue | |
| 3938 // -- Deal with possible overflow issues: | |
| 3939 // . local work-queue overflow causes stuff to be pushed on | |
| 3940 // global (common) overflow queue | |
| 3941 // . always first empty local work queue | |
| 3942 // . then get a batch of oops from global work queue if any | |
| 3943 // . then do work stealing | |
| 3944 // -- When all tasks claimed (both spaces) | |
| 3945 // and local work queue empty, | |
| 3946 // then in a loop do: | |
| 3947 // . check global overflow stack; steal a batch of oops and trace | |
| 3948 // . try to steal from other threads oif GOS is empty | |
| 3949 // . if neither is available, offer termination | |
| 3950 // -- Terminate and return result | |
| 3951 // | |
|
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3952 void CMSConcMarkingTask::work(uint worker_id) { |
| 0 | 3953 elapsedTimer _timer; |
| 3954 ResourceMark rm; | |
| 3955 HandleMark hm; | |
| 3956 | |
| 3957 DEBUG_ONLY(_collector->verify_overflow_empty();) | |
| 3958 | |
| 3959 // Before we begin work, our work queue should be empty | |
|
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3960 assert(work_queue(worker_id)->size() == 0, "Expected to be empty"); |
| 0 | 3961 // Scan the bitmap covering _cms_space, tracing through grey objects. |
| 3962 _timer.start(); | |
|
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3963 do_scan_and_mark(worker_id, _cms_space); |
| 0 | 3964 _timer.stop(); |
| 3965 if (PrintCMSStatistics != 0) { | |
| 3966 gclog_or_tty->print_cr("Finished cms space scanning in %dth thread: %3.3f sec", | |
|
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3967 worker_id, _timer.seconds()); |
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3968 // XXX: need xxx/xxx type of notation, two timers |
| 0 | 3969 } |
| 3970 | |
| 3971 // ... do work stealing | |
| 3972 _timer.reset(); | |
| 3973 _timer.start(); | |
|
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3974 do_work_steal(worker_id); |
| 0 | 3975 _timer.stop(); |
| 3976 if (PrintCMSStatistics != 0) { | |
| 3977 gclog_or_tty->print_cr("Finished work stealing in %dth thread: %3.3f sec", | |
|
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3978 worker_id, _timer.seconds()); |
|
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3979 // XXX: need xxx/xxx type of notation, two timers |
| 0 | 3980 } |
| 3981 assert(_collector->_markStack.isEmpty(), "Should have been emptied"); | |
|
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3982 assert(work_queue(worker_id)->size() == 0, "Should have been emptied"); |
| 0 | 3983 // Note that under the current task protocol, the |
| 3984 // following assertion is true even of the spaces | |
| 3985 // expanded since the completion of the concurrent | |
| 3986 // marking. XXX This will likely change under a strict | |
| 3987 // ABORT semantics. | |
|
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3988 // After perm removal the comparison was changed to |
|
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3989 // greater than or equal to from strictly greater than. |
|
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3990 // Before perm removal the highest address sweep would |
|
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3991 // have been at the end of perm gen but now is at the |
|
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3992 // end of the tenured gen. |
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3993 assert(_global_finger >= _cms_space->end(), |
| 0 | 3994 "All tasks have been completed"); |
| 3995 DEBUG_ONLY(_collector->verify_overflow_empty();) | |
| 3996 } | |
| 3997 | |
| 3998 void CMSConcMarkingTask::bump_global_finger(HeapWord* f) { | |
| 3999 HeapWord* read = _global_finger; | |
| 4000 HeapWord* cur = read; | |
| 4001 while (f > read) { | |
| 4002 cur = read; | |
| 4003 read = (HeapWord*) Atomic::cmpxchg_ptr(f, &_global_finger, cur); | |
| 4004 if (cur == read) { | |
| 4005 // our cas succeeded | |
| 4006 assert(_global_finger >= f, "protocol consistency"); | |
| 4007 break; | |
| 4008 } | |
| 4009 } | |
| 4010 } | |
| 4011 | |
| 4012 // This is really inefficient, and should be redone by | |
| 4013 // using (not yet available) block-read and -write interfaces to the | |
| 4014 // stack and the work_queue. XXX FIX ME !!! | |
| 4015 bool CMSConcMarkingTask::get_work_from_overflow_stack(CMSMarkStack* ovflw_stk, | |
| 4016 OopTaskQueue* work_q) { | |
| 4017 // Fast lock-free check | |
| 4018 if (ovflw_stk->length() == 0) { | |
| 4019 return false; | |
| 4020 } | |
| 4021 assert(work_q->size() == 0, "Shouldn't steal"); | |
| 4022 MutexLockerEx ml(ovflw_stk->par_lock(), | |
| 4023 Mutex::_no_safepoint_check_flag); | |
| 4024 // Grab up to 1/4 the size of the work queue | |
|
679
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|
4025 size_t num = MIN2((size_t)(work_q->max_elems() - work_q->size())/4, |
| 0 | 4026 (size_t)ParGCDesiredObjsFromOverflowList); |
| 4027 num = MIN2(num, ovflw_stk->length()); | |
| 4028 for (int i = (int) num; i > 0; i--) { | |
| 4029 oop cur = ovflw_stk->pop(); | |
| 4030 assert(cur != NULL, "Counted wrong?"); | |
| 4031 work_q->push(cur); | |
| 4032 } | |
| 4033 return num > 0; | |
| 4034 } | |
| 4035 | |
| 4036 void CMSConcMarkingTask::do_scan_and_mark(int i, CompactibleFreeListSpace* sp) { | |
| 4037 SequentialSubTasksDone* pst = sp->conc_par_seq_tasks(); | |
| 4038 int n_tasks = pst->n_tasks(); | |
| 4039 // We allow that there may be no tasks to do here because | |
| 4040 // we are restarting after a stack overflow. | |
|
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4041 assert(pst->valid() || n_tasks == 0, "Uninitialized use?"); |
|
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4042 uint nth_task = 0; |
| 0 | 4043 |
|
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4044 HeapWord* aligned_start = sp->bottom(); |
|
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4045 if (sp->used_region().contains(_restart_addr)) { |
|
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4046 // Align down to a card boundary for the start of 0th task |
|
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4047 // for this space. |
|
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|
4048 aligned_start = |
|
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|
4049 (HeapWord*)align_size_down((uintptr_t)_restart_addr, |
|
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4050 CardTableModRefBS::card_size); |
|
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4051 } |
|
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4052 |
| 0 | 4053 size_t chunk_size = sp->marking_task_size(); |
| 4054 while (!pst->is_task_claimed(/* reference */ nth_task)) { | |
| 4055 // Having claimed the nth task in this space, | |
| 4056 // compute the chunk that it corresponds to: | |
|
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4057 MemRegion span = MemRegion(aligned_start + nth_task*chunk_size, |
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4058 aligned_start + (nth_task+1)*chunk_size); |
| 0 | 4059 // Try and bump the global finger via a CAS; |
| 4060 // note that we need to do the global finger bump | |
| 4061 // _before_ taking the intersection below, because | |
| 4062 // the task corresponding to that region will be | |
| 4063 // deemed done even if the used_region() expands | |
| 4064 // because of allocation -- as it almost certainly will | |
| 4065 // during start-up while the threads yield in the | |
| 4066 // closure below. | |
| 4067 HeapWord* finger = span.end(); | |
| 4068 bump_global_finger(finger); // atomically | |
| 4069 // There are null tasks here corresponding to chunks | |
| 4070 // beyond the "top" address of the space. | |
| 4071 span = span.intersection(sp->used_region()); | |
| 4072 if (!span.is_empty()) { // Non-null task | |
|
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|
4073 HeapWord* prev_obj; |
|
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|
4074 assert(!span.contains(_restart_addr) || nth_task == 0, |
|
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|
4075 "Inconsistency"); |
|
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|
4076 if (nth_task == 0) { |
|
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|
4077 // For the 0th task, we'll not need to compute a block_start. |
|
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4078 if (span.contains(_restart_addr)) { |
|
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4079 // In the case of a restart because of stack overflow, |
|
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4080 // we might additionally skip a chunk prefix. |
|
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4081 prev_obj = _restart_addr; |
| 0 | 4082 } else { |
|
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4083 prev_obj = span.start(); |
|
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|
4084 } |
|
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4085 } else { |
|
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|
4086 // We want to skip the first object because |
|
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|
4087 // the protocol is to scan any object in its entirety |
|
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4088 // that _starts_ in this span; a fortiori, any |
|
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4089 // object starting in an earlier span is scanned |
|
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|
4090 // as part of an earlier claimed task. |
|
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|
4091 // Below we use the "careful" version of block_start |
|
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|
4092 // so we do not try to navigate uninitialized objects. |
|
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|
4093 prev_obj = sp->block_start_careful(span.start()); |
|
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|
4094 // Below we use a variant of block_size that uses the |
|
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|
4095 // Printezis bits to avoid waiting for allocated |
|
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|
4096 // objects to become initialized/parsable. |
|
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|
4097 while (prev_obj < span.start()) { |
|
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|
4098 size_t sz = sp->block_size_no_stall(prev_obj, _collector); |
|
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4099 if (sz > 0) { |
|
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4100 prev_obj += sz; |
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4101 } else { |
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4102 // In this case we may end up doing a bit of redundant |
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4103 // scanning, but that appears unavoidable, short of |
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4104 // locking the free list locks; see bug 6324141. |
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4105 break; |
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4106 } |
| 0 | 4107 } |
| 4108 } | |
| 4109 if (prev_obj < span.end()) { | |
| 4110 MemRegion my_span = MemRegion(prev_obj, span.end()); | |
| 4111 // Do the marking work within a non-empty span -- | |
| 4112 // the last argument to the constructor indicates whether the | |
| 4113 // iteration should be incremental with periodic yields. | |
| 4114 Par_MarkFromRootsClosure cl(this, _collector, my_span, | |
| 4115 &_collector->_markBitMap, | |
| 4116 work_queue(i), | |
| 4117 &_collector->_markStack, | |
| 4118 _asynch); | |
| 4119 _collector->_markBitMap.iterate(&cl, my_span.start(), my_span.end()); | |
| 4120 } // else nothing to do for this task | |
| 4121 } // else nothing to do for this task | |
| 4122 } | |
| 4123 // We'd be tempted to assert here that since there are no | |
| 4124 // more tasks left to claim in this space, the global_finger | |
| 4125 // must exceed space->top() and a fortiori space->end(). However, | |
| 4126 // that would not quite be correct because the bumping of | |
| 4127 // global_finger occurs strictly after the claiming of a task, | |
| 4128 // so by the time we reach here the global finger may not yet | |
| 4129 // have been bumped up by the thread that claimed the last | |
| 4130 // task. | |
| 4131 pst->all_tasks_completed(); | |
| 4132 } | |
| 4133 | |
|
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4134 class Par_ConcMarkingClosure: public CMSOopClosure { |
|
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4135 private: |
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4136 CMSCollector* _collector; |
|
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4137 CMSConcMarkingTask* _task; |
| 0 | 4138 MemRegion _span; |
| 4139 CMSBitMap* _bit_map; | |
| 4140 CMSMarkStack* _overflow_stack; | |
| 4141 OopTaskQueue* _work_queue; | |
|
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4142 protected: |
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4143 DO_OOP_WORK_DEFN |
| 0 | 4144 public: |
|
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4145 Par_ConcMarkingClosure(CMSCollector* collector, CMSConcMarkingTask* task, OopTaskQueue* work_queue, |
|
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4146 CMSBitMap* bit_map, CMSMarkStack* overflow_stack): |
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4147 CMSOopClosure(collector->ref_processor()), |
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4148 _collector(collector), |
|
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4149 _task(task), |
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4150 _span(collector->_span), |
| 0 | 4151 _work_queue(work_queue), |
| 4152 _bit_map(bit_map), | |
| 935 | 4153 _overflow_stack(overflow_stack) |
| 4154 { } | |
|
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4155 virtual void do_oop(oop* p); |
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4156 virtual void do_oop(narrowOop* p); |
|
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4157 |
| 0 | 4158 void trim_queue(size_t max); |
| 4159 void handle_stack_overflow(HeapWord* lost); | |
|
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4160 void do_yield_check() { |
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4161 if (_task->should_yield()) { |
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4162 _task->yield(); |
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4163 } |
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4164 } |
| 0 | 4165 }; |
| 4166 | |
|
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4167 // Grey object scanning during work stealing phase -- |
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4168 // the salient assumption here is that any references |
|
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4169 // that are in these stolen objects being scanned must |
|
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4170 // already have been initialized (else they would not have |
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4171 // been published), so we do not need to check for |
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4172 // uninitialized objects before pushing here. |
|
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4173 void Par_ConcMarkingClosure::do_oop(oop obj) { |
|
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4174 assert(obj->is_oop_or_null(true), "expected an oop or NULL"); |
|
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4175 HeapWord* addr = (HeapWord*)obj; |
| 0 | 4176 // Check if oop points into the CMS generation |
| 4177 // and is not marked | |
| 4178 if (_span.contains(addr) && !_bit_map->isMarked(addr)) { | |
| 4179 // a white object ... | |
| 4180 // If we manage to "claim" the object, by being the | |
| 4181 // first thread to mark it, then we push it on our | |
| 4182 // marking stack | |
| 4183 if (_bit_map->par_mark(addr)) { // ... now grey | |
| 4184 // push on work queue (grey set) | |
| 4185 bool simulate_overflow = false; | |
| 4186 NOT_PRODUCT( | |
| 4187 if (CMSMarkStackOverflowALot && | |
| 4188 _collector->simulate_overflow()) { | |
| 4189 // simulate a stack overflow | |
| 4190 simulate_overflow = true; | |
| 4191 } | |
| 4192 ) | |
| 4193 if (simulate_overflow || | |
|
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4194 !(_work_queue->push(obj) || _overflow_stack->par_push(obj))) { |
| 0 | 4195 // stack overflow |
| 4196 if (PrintCMSStatistics != 0) { | |
| 4197 gclog_or_tty->print_cr("CMS marking stack overflow (benign) at " | |
| 4198 SIZE_FORMAT, _overflow_stack->capacity()); | |
| 4199 } | |
| 4200 // We cannot assert that the overflow stack is full because | |
| 4201 // it may have been emptied since. | |
| 4202 assert(simulate_overflow || | |
| 4203 _work_queue->size() == _work_queue->max_elems(), | |
| 4204 "Else push should have succeeded"); | |
| 4205 handle_stack_overflow(addr); | |
| 4206 } | |
| 4207 } // Else, some other thread got there first | |
|
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4208 do_yield_check(); |
| 0 | 4209 } |
| 4210 } | |
| 4211 | |
|
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4212 void Par_ConcMarkingClosure::do_oop(oop* p) { Par_ConcMarkingClosure::do_oop_work(p); } |
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4213 void Par_ConcMarkingClosure::do_oop(narrowOop* p) { Par_ConcMarkingClosure::do_oop_work(p); } |
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4214 |
| 0 | 4215 void Par_ConcMarkingClosure::trim_queue(size_t max) { |
| 4216 while (_work_queue->size() > max) { | |
| 4217 oop new_oop; | |
| 4218 if (_work_queue->pop_local(new_oop)) { | |
| 4219 assert(new_oop->is_oop(), "Should be an oop"); | |
| 4220 assert(_bit_map->isMarked((HeapWord*)new_oop), "Grey object"); | |
| 4221 assert(_span.contains((HeapWord*)new_oop), "Not in span"); | |
| 4222 new_oop->oop_iterate(this); // do_oop() above | |
|
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4223 do_yield_check(); |
| 0 | 4224 } |
| 4225 } | |
| 4226 } | |
| 4227 | |
| 4228 // Upon stack overflow, we discard (part of) the stack, | |
| 4229 // remembering the least address amongst those discarded | |
| 4230 // in CMSCollector's _restart_address. | |
| 4231 void Par_ConcMarkingClosure::handle_stack_overflow(HeapWord* lost) { | |
| 4232 // We need to do this under a mutex to prevent other | |
|
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4233 // workers from interfering with the work done below. |
| 0 | 4234 MutexLockerEx ml(_overflow_stack->par_lock(), |
| 4235 Mutex::_no_safepoint_check_flag); | |
| 4236 // Remember the least grey address discarded | |
| 4237 HeapWord* ra = (HeapWord*)_overflow_stack->least_value(lost); | |
| 4238 _collector->lower_restart_addr(ra); | |
| 4239 _overflow_stack->reset(); // discard stack contents | |
| 4240 _overflow_stack->expand(); // expand the stack if possible | |
| 4241 } | |
| 4242 | |
| 4243 | |
| 4244 void CMSConcMarkingTask::do_work_steal(int i) { | |
| 4245 OopTaskQueue* work_q = work_queue(i); | |
| 4246 oop obj_to_scan; | |
| 4247 CMSBitMap* bm = &(_collector->_markBitMap); | |
| 4248 CMSMarkStack* ovflw = &(_collector->_markStack); | |
| 4249 int* seed = _collector->hash_seed(i); | |
|
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4250 Par_ConcMarkingClosure cl(_collector, this, work_q, bm, ovflw); |
| 0 | 4251 while (true) { |
| 4252 cl.trim_queue(0); | |
| 4253 assert(work_q->size() == 0, "Should have been emptied above"); | |
| 4254 if (get_work_from_overflow_stack(ovflw, work_q)) { | |
| 4255 // Can't assert below because the work obtained from the | |
| 4256 // overflow stack may already have been stolen from us. | |
| 4257 // assert(work_q->size() > 0, "Work from overflow stack"); | |
| 4258 continue; | |
| 4259 } else if (task_queues()->steal(i, seed, /* reference */ obj_to_scan)) { | |
| 4260 assert(obj_to_scan->is_oop(), "Should be an oop"); | |
| 4261 assert(bm->isMarked((HeapWord*)obj_to_scan), "Grey object"); | |
| 4262 obj_to_scan->oop_iterate(&cl); | |
|
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|
4263 } else if (terminator()->offer_termination(&_term_term)) { |
| 0 | 4264 assert(work_q->size() == 0, "Impossible!"); |
| 4265 break; | |
|
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|
4266 } else if (yielding() || should_yield()) { |
|
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|
4267 yield(); |
| 0 | 4268 } |
| 4269 } | |
| 4270 } | |
| 4271 | |
| 4272 // This is run by the CMS (coordinator) thread. | |
| 4273 void CMSConcMarkingTask::coordinator_yield() { | |
| 4274 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 4275 "CMS thread should hold CMS token"); | |
| 4276 // First give up the locks, then yield, then re-lock | |
| 4277 // We should probably use a constructor/destructor idiom to | |
| 4278 // do this unlock/lock or modify the MutexUnlocker class to | |
| 4279 // serve our purpose. XXX | |
| 4280 assert_lock_strong(_bit_map_lock); | |
| 4281 _bit_map_lock->unlock(); | |
| 4282 ConcurrentMarkSweepThread::desynchronize(true); | |
| 4283 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 4284 _collector->stopTimer(); | |
| 4285 if (PrintCMSStatistics != 0) { | |
| 4286 _collector->incrementYields(); | |
| 4287 } | |
| 4288 _collector->icms_wait(); | |
| 4289 | |
| 4290 // It is possible for whichever thread initiated the yield request | |
| 4291 // not to get a chance to wake up and take the bitmap lock between | |
| 4292 // this thread releasing it and reacquiring it. So, while the | |
| 4293 // should_yield() flag is on, let's sleep for a bit to give the | |
| 4294 // other thread a chance to wake up. The limit imposed on the number | |
| 4295 // of iterations is defensive, to avoid any unforseen circumstances | |
| 4296 // putting us into an infinite loop. Since it's always been this | |
| 4297 // (coordinator_yield()) method that was observed to cause the | |
| 4298 // problem, we are using a parameter (CMSCoordinatorYieldSleepCount) | |
| 4299 // which is by default non-zero. For the other seven methods that | |
| 4300 // also perform the yield operation, as are using a different | |
| 4301 // parameter (CMSYieldSleepCount) which is by default zero. This way we | |
| 4302 // can enable the sleeping for those methods too, if necessary. | |
| 4303 // See 6442774. | |
| 4304 // | |
| 4305 // We really need to reconsider the synchronization between the GC | |
| 4306 // thread and the yield-requesting threads in the future and we | |
| 4307 // should really use wait/notify, which is the recommended | |
| 4308 // way of doing this type of interaction. Additionally, we should | |
| 4309 // consolidate the eight methods that do the yield operation and they | |
| 4310 // are almost identical into one for better maintenability and | |
| 4311 // readability. See 6445193. | |
| 4312 // | |
| 4313 // Tony 2006.06.29 | |
| 4314 for (unsigned i = 0; i < CMSCoordinatorYieldSleepCount && | |
|
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4315 ConcurrentMarkSweepThread::should_yield() && |
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4316 !CMSCollector::foregroundGCIsActive(); ++i) { |
| 0 | 4317 os::sleep(Thread::current(), 1, false); |
| 4318 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 4319 } | |
| 4320 | |
| 4321 ConcurrentMarkSweepThread::synchronize(true); | |
| 4322 _bit_map_lock->lock_without_safepoint_check(); | |
| 4323 _collector->startTimer(); | |
| 4324 } | |
| 4325 | |
| 4326 bool CMSCollector::do_marking_mt(bool asynch) { | |
| 1284 | 4327 assert(ConcGCThreads > 0 && conc_workers() != NULL, "precondition"); |
|
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4328 int num_workers = AdaptiveSizePolicy::calc_active_conc_workers( |
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4329 conc_workers()->total_workers(), |
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4330 conc_workers()->active_workers(), |
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4331 Threads::number_of_non_daemon_threads()); |
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|
4332 conc_workers()->set_active_workers(num_workers); |
| 0 | 4333 |
| 4334 CompactibleFreeListSpace* cms_space = _cmsGen->cmsSpace(); | |
| 4335 | |
|
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4336 CMSConcMarkingTask tsk(this, |
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4337 cms_space, |
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4338 asynch, |
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4339 conc_workers(), |
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4340 task_queues()); |
| 0 | 4341 |
| 4342 // Since the actual number of workers we get may be different | |
| 4343 // from the number we requested above, do we need to do anything different | |
| 4344 // below? In particular, may be we need to subclass the SequantialSubTasksDone | |
| 4345 // class?? XXX | |
| 4346 cms_space ->initialize_sequential_subtasks_for_marking(num_workers); | |
| 4347 | |
| 4348 // Refs discovery is already non-atomic. | |
| 4349 assert(!ref_processor()->discovery_is_atomic(), "Should be non-atomic"); | |
|
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|
4350 assert(ref_processor()->discovery_is_mt(), "Discovery should be MT"); |
| 0 | 4351 conc_workers()->start_task(&tsk); |
| 4352 while (tsk.yielded()) { | |
| 4353 tsk.coordinator_yield(); | |
| 4354 conc_workers()->continue_task(&tsk); | |
| 4355 } | |
| 4356 // If the task was aborted, _restart_addr will be non-NULL | |
| 4357 assert(tsk.completed() || _restart_addr != NULL, "Inconsistency"); | |
| 4358 while (_restart_addr != NULL) { | |
| 4359 // XXX For now we do not make use of ABORTED state and have not | |
| 4360 // yet implemented the right abort semantics (even in the original | |
| 4361 // single-threaded CMS case). That needs some more investigation | |
| 4362 // and is deferred for now; see CR# TBF. 07252005YSR. XXX | |
| 4363 assert(!CMSAbortSemantics || tsk.aborted(), "Inconsistency"); | |
| 4364 // If _restart_addr is non-NULL, a marking stack overflow | |
| 605 | 4365 // occurred; we need to do a fresh marking iteration from the |
| 0 | 4366 // indicated restart address. |
| 4367 if (_foregroundGCIsActive && asynch) { | |
| 4368 // We may be running into repeated stack overflows, having | |
| 4369 // reached the limit of the stack size, while making very | |
| 4370 // slow forward progress. It may be best to bail out and | |
| 4371 // let the foreground collector do its job. | |
| 4372 // Clear _restart_addr, so that foreground GC | |
| 4373 // works from scratch. This avoids the headache of | |
| 4374 // a "rescan" which would otherwise be needed because | |
| 4375 // of the dirty mod union table & card table. | |
| 4376 _restart_addr = NULL; | |
| 4377 return false; | |
| 4378 } | |
| 4379 // Adjust the task to restart from _restart_addr | |
| 4380 tsk.reset(_restart_addr); | |
| 4381 cms_space ->initialize_sequential_subtasks_for_marking(num_workers, | |
| 4382 _restart_addr); | |
| 4383 _restart_addr = NULL; | |
| 4384 // Get the workers going again | |
| 4385 conc_workers()->start_task(&tsk); | |
| 4386 while (tsk.yielded()) { | |
| 4387 tsk.coordinator_yield(); | |
| 4388 conc_workers()->continue_task(&tsk); | |
| 4389 } | |
| 4390 } | |
| 4391 assert(tsk.completed(), "Inconsistency"); | |
| 4392 assert(tsk.result() == true, "Inconsistency"); | |
| 4393 return true; | |
| 4394 } | |
| 4395 | |
| 4396 bool CMSCollector::do_marking_st(bool asynch) { | |
| 4397 ResourceMark rm; | |
| 4398 HandleMark hm; | |
| 4399 | |
|
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4400 // Temporarily make refs discovery single threaded (non-MT) |
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4401 ReferenceProcessorMTDiscoveryMutator rp_mut_discovery(ref_processor(), false); |
| 0 | 4402 MarkFromRootsClosure markFromRootsClosure(this, _span, &_markBitMap, |
|
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4403 &_markStack, CMSYield && asynch); |
| 0 | 4404 // the last argument to iterate indicates whether the iteration |
| 4405 // should be incremental with periodic yields. | |
| 4406 _markBitMap.iterate(&markFromRootsClosure); | |
| 4407 // If _restart_addr is non-NULL, a marking stack overflow | |
| 605 | 4408 // occurred; we need to do a fresh iteration from the |
| 0 | 4409 // indicated restart address. |
| 4410 while (_restart_addr != NULL) { | |
| 4411 if (_foregroundGCIsActive && asynch) { | |
| 4412 // We may be running into repeated stack overflows, having | |
| 4413 // reached the limit of the stack size, while making very | |
| 4414 // slow forward progress. It may be best to bail out and | |
| 4415 // let the foreground collector do its job. | |
| 4416 // Clear _restart_addr, so that foreground GC | |
| 4417 // works from scratch. This avoids the headache of | |
| 4418 // a "rescan" which would otherwise be needed because | |
| 4419 // of the dirty mod union table & card table. | |
| 4420 _restart_addr = NULL; | |
| 4421 return false; // indicating failure to complete marking | |
| 4422 } | |
| 4423 // Deal with stack overflow: | |
| 4424 // we restart marking from _restart_addr | |
| 4425 HeapWord* ra = _restart_addr; | |
| 4426 markFromRootsClosure.reset(ra); | |
| 4427 _restart_addr = NULL; | |
| 4428 _markBitMap.iterate(&markFromRootsClosure, ra, _span.end()); | |
| 4429 } | |
| 4430 return true; | |
| 4431 } | |
| 4432 | |
| 4433 void CMSCollector::preclean() { | |
| 4434 check_correct_thread_executing(); | |
| 4435 assert(Thread::current()->is_ConcurrentGC_thread(), "Wrong thread"); | |
| 4436 verify_work_stacks_empty(); | |
| 4437 verify_overflow_empty(); | |
| 4438 _abort_preclean = false; | |
| 4439 if (CMSPrecleaningEnabled) { | |
| 4440 _eden_chunk_index = 0; | |
| 4441 size_t used = get_eden_used(); | |
| 4442 size_t capacity = get_eden_capacity(); | |
| 4443 // Don't start sampling unless we will get sufficiently | |
| 4444 // many samples. | |
| 4445 if (used < (capacity/(CMSScheduleRemarkSamplingRatio * 100) | |
| 4446 * CMSScheduleRemarkEdenPenetration)) { | |
| 4447 _start_sampling = true; | |
| 4448 } else { | |
| 4449 _start_sampling = false; | |
| 4450 } | |
| 4451 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
| 4452 CMSPhaseAccounting pa(this, "preclean", !PrintGCDetails); | |
| 4453 preclean_work(CMSPrecleanRefLists1, CMSPrecleanSurvivors1); | |
| 4454 } | |
| 4455 CMSTokenSync x(true); // is cms thread | |
| 4456 if (CMSPrecleaningEnabled) { | |
| 4457 sample_eden(); | |
| 4458 _collectorState = AbortablePreclean; | |
| 4459 } else { | |
| 4460 _collectorState = FinalMarking; | |
| 4461 } | |
| 4462 verify_work_stacks_empty(); | |
| 4463 verify_overflow_empty(); | |
| 4464 } | |
| 4465 | |
| 4466 // Try and schedule the remark such that young gen | |
| 4467 // occupancy is CMSScheduleRemarkEdenPenetration %. | |
| 4468 void CMSCollector::abortable_preclean() { | |
| 4469 check_correct_thread_executing(); | |
| 4470 assert(CMSPrecleaningEnabled, "Inconsistent control state"); | |
| 4471 assert(_collectorState == AbortablePreclean, "Inconsistent control state"); | |
| 4472 | |
| 4473 // If Eden's current occupancy is below this threshold, | |
| 4474 // immediately schedule the remark; else preclean | |
| 4475 // past the next scavenge in an effort to | |
| 4476 // schedule the pause as described avove. By choosing | |
| 4477 // CMSScheduleRemarkEdenSizeThreshold >= max eden size | |
| 4478 // we will never do an actual abortable preclean cycle. | |
| 4479 if (get_eden_used() > CMSScheduleRemarkEdenSizeThreshold) { | |
| 4480 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
| 4481 CMSPhaseAccounting pa(this, "abortable-preclean", !PrintGCDetails); | |
| 4482 // We need more smarts in the abortable preclean | |
| 4483 // loop below to deal with cases where allocation | |
| 4484 // in young gen is very very slow, and our precleaning | |
| 4485 // is running a losing race against a horde of | |
| 4486 // mutators intent on flooding us with CMS updates | |
| 4487 // (dirty cards). | |
| 4488 // One, admittedly dumb, strategy is to give up | |
| 4489 // after a certain number of abortable precleaning loops | |
| 4490 // or after a certain maximum time. We want to make | |
| 4491 // this smarter in the next iteration. | |
| 4492 // XXX FIX ME!!! YSR | |
| 4493 size_t loops = 0, workdone = 0, cumworkdone = 0, waited = 0; | |
| 4494 while (!(should_abort_preclean() || | |
| 4495 ConcurrentMarkSweepThread::should_terminate())) { | |
| 4496 workdone = preclean_work(CMSPrecleanRefLists2, CMSPrecleanSurvivors2); | |
| 4497 cumworkdone += workdone; | |
| 4498 loops++; | |
| 4499 // Voluntarily terminate abortable preclean phase if we have | |
| 4500 // been at it for too long. | |
| 4501 if ((CMSMaxAbortablePrecleanLoops != 0) && | |
| 4502 loops >= CMSMaxAbortablePrecleanLoops) { | |
| 4503 if (PrintGCDetails) { | |
| 4504 gclog_or_tty->print(" CMS: abort preclean due to loops "); | |
| 4505 } | |
| 4506 break; | |
| 4507 } | |
| 4508 if (pa.wallclock_millis() > CMSMaxAbortablePrecleanTime) { | |
| 4509 if (PrintGCDetails) { | |
| 4510 gclog_or_tty->print(" CMS: abort preclean due to time "); | |
| 4511 } | |
| 4512 break; | |
| 4513 } | |
| 4514 // If we are doing little work each iteration, we should | |
| 4515 // take a short break. | |
| 4516 if (workdone < CMSAbortablePrecleanMinWorkPerIteration) { | |
| 4517 // Sleep for some time, waiting for work to accumulate | |
| 4518 stopTimer(); | |
| 4519 cmsThread()->wait_on_cms_lock(CMSAbortablePrecleanWaitMillis); | |
| 4520 startTimer(); | |
| 4521 waited++; | |
| 4522 } | |
| 4523 } | |
| 4524 if (PrintCMSStatistics > 0) { | |
| 4525 gclog_or_tty->print(" [%d iterations, %d waits, %d cards)] ", | |
| 4526 loops, waited, cumworkdone); | |
| 4527 } | |
| 4528 } | |
| 4529 CMSTokenSync x(true); // is cms thread | |
| 4530 if (_collectorState != Idling) { | |
| 4531 assert(_collectorState == AbortablePreclean, | |
| 4532 "Spontaneous state transition?"); | |
| 4533 _collectorState = FinalMarking; | |
| 4534 } // Else, a foreground collection completed this CMS cycle. | |
| 4535 return; | |
| 4536 } | |
| 4537 | |
| 4538 // Respond to an Eden sampling opportunity | |
| 4539 void CMSCollector::sample_eden() { | |
| 4540 // Make sure a young gc cannot sneak in between our | |
| 4541 // reading and recording of a sample. | |
| 4542 assert(Thread::current()->is_ConcurrentGC_thread(), | |
| 4543 "Only the cms thread may collect Eden samples"); | |
| 4544 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 4545 "Should collect samples while holding CMS token"); | |
| 4546 if (!_start_sampling) { | |
| 4547 return; | |
| 4548 } | |
| 4549 if (_eden_chunk_array) { | |
| 4550 if (_eden_chunk_index < _eden_chunk_capacity) { | |
| 4551 _eden_chunk_array[_eden_chunk_index] = *_top_addr; // take sample | |
| 4552 assert(_eden_chunk_array[_eden_chunk_index] <= *_end_addr, | |
| 4553 "Unexpected state of Eden"); | |
| 4554 // We'd like to check that what we just sampled is an oop-start address; | |
| 4555 // however, we cannot do that here since the object may not yet have been | |
| 4556 // initialized. So we'll instead do the check when we _use_ this sample | |
| 4557 // later. | |
| 4558 if (_eden_chunk_index == 0 || | |
| 4559 (pointer_delta(_eden_chunk_array[_eden_chunk_index], | |
| 4560 _eden_chunk_array[_eden_chunk_index-1]) | |
| 4561 >= CMSSamplingGrain)) { | |
| 4562 _eden_chunk_index++; // commit sample | |
| 4563 } | |
| 4564 } | |
| 4565 } | |
| 4566 if ((_collectorState == AbortablePreclean) && !_abort_preclean) { | |
| 4567 size_t used = get_eden_used(); | |
| 4568 size_t capacity = get_eden_capacity(); | |
| 4569 assert(used <= capacity, "Unexpected state of Eden"); | |
| 4570 if (used > (capacity/100 * CMSScheduleRemarkEdenPenetration)) { | |
| 4571 _abort_preclean = true; | |
| 4572 } | |
| 4573 } | |
| 4574 } | |
| 4575 | |
| 4576 | |
| 4577 size_t CMSCollector::preclean_work(bool clean_refs, bool clean_survivor) { | |
| 4578 assert(_collectorState == Precleaning || | |
| 4579 _collectorState == AbortablePreclean, "incorrect state"); | |
| 4580 ResourceMark rm; | |
| 4581 HandleMark hm; | |
|
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4582 |
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4583 // Precleaning is currently not MT but the reference processor |
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4584 // may be set for MT. Disable it temporarily here. |
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4585 ReferenceProcessor* rp = ref_processor(); |
|
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4586 ReferenceProcessorMTDiscoveryMutator rp_mut_discovery(rp, false); |
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4587 |
| 0 | 4588 // Do one pass of scrubbing the discovered reference lists |
| 4589 // to remove any reference objects with strongly-reachable | |
| 4590 // referents. | |
| 4591 if (clean_refs) { | |
| 4592 CMSPrecleanRefsYieldClosure yield_cl(this); | |
| 4593 assert(rp->span().equals(_span), "Spans should be equal"); | |
| 4594 CMSKeepAliveClosure keep_alive(this, _span, &_markBitMap, | |
|
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4595 &_markStack, true /* preclean */); |
| 0 | 4596 CMSDrainMarkingStackClosure complete_trace(this, |
|
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4597 _span, &_markBitMap, &_markStack, |
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|
4598 &keep_alive, true /* preclean */); |
| 0 | 4599 |
| 4600 // We don't want this step to interfere with a young | |
| 4601 // collection because we don't want to take CPU | |
| 4602 // or memory bandwidth away from the young GC threads | |
| 4603 // (which may be as many as there are CPUs). | |
| 4604 // Note that we don't need to protect ourselves from | |
| 4605 // interference with mutators because they can't | |
| 4606 // manipulate the discovered reference lists nor affect | |
| 4607 // the computed reachability of the referents, the | |
| 4608 // only properties manipulated by the precleaning | |
| 4609 // of these reference lists. | |
| 4610 stopTimer(); | |
| 4611 CMSTokenSyncWithLocks x(true /* is cms thread */, | |
| 4612 bitMapLock()); | |
| 4613 startTimer(); | |
| 4614 sample_eden(); | |
| 935 | 4615 |
| 0 | 4616 // The following will yield to allow foreground |
| 4617 // collection to proceed promptly. XXX YSR: | |
| 4618 // The code in this method may need further | |
| 4619 // tweaking for better performance and some restructuring | |
| 4620 // for cleaner interfaces. | |
| 10405 | 4621 GCTimer *gc_timer = NULL; // Currently not tracing concurrent phases |
| 0 | 4622 rp->preclean_discovered_references( |
| 10405 | 4623 rp->is_alive_non_header(), &keep_alive, &complete_trace, &yield_cl, |
| 4624 gc_timer); | |
| 0 | 4625 } |
| 4626 | |
| 4627 if (clean_survivor) { // preclean the active survivor space(s) | |
| 4628 assert(_young_gen->kind() == Generation::DefNew || | |
| 4629 _young_gen->kind() == Generation::ParNew || | |
| 4630 _young_gen->kind() == Generation::ASParNew, | |
| 4631 "incorrect type for cast"); | |
| 4632 DefNewGeneration* dng = (DefNewGeneration*)_young_gen; | |
| 4633 PushAndMarkClosure pam_cl(this, _span, ref_processor(), | |
| 4634 &_markBitMap, &_modUnionTable, | |
|
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4635 &_markStack, true /* precleaning phase */); |
| 0 | 4636 stopTimer(); |
| 4637 CMSTokenSyncWithLocks ts(true /* is cms thread */, | |
| 4638 bitMapLock()); | |
| 4639 startTimer(); | |
| 4640 unsigned int before_count = | |
| 4641 GenCollectedHeap::heap()->total_collections(); | |
| 4642 SurvivorSpacePrecleanClosure | |
| 4643 sss_cl(this, _span, &_markBitMap, &_markStack, | |
| 4644 &pam_cl, before_count, CMSYield); | |
| 4645 dng->from()->object_iterate_careful(&sss_cl); | |
| 4646 dng->to()->object_iterate_careful(&sss_cl); | |
| 4647 } | |
| 4648 MarkRefsIntoAndScanClosure | |
| 4649 mrias_cl(_span, ref_processor(), &_markBitMap, &_modUnionTable, | |
|
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4650 &_markStack, this, CMSYield, |
| 0 | 4651 true /* precleaning phase */); |
| 4652 // CAUTION: The following closure has persistent state that may need to | |
| 4653 // be reset upon a decrease in the sequence of addresses it | |
| 4654 // processes. | |
| 4655 ScanMarkedObjectsAgainCarefullyClosure | |
| 4656 smoac_cl(this, _span, | |
|
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4657 &_markBitMap, &_markStack, &mrias_cl, CMSYield); |
| 0 | 4658 |
| 4659 // Preclean dirty cards in ModUnionTable and CardTable using | |
| 4660 // appropriate convergence criterion; | |
| 4661 // repeat CMSPrecleanIter times unless we find that | |
| 4662 // we are losing. | |
| 4663 assert(CMSPrecleanIter < 10, "CMSPrecleanIter is too large"); | |
| 4664 assert(CMSPrecleanNumerator < CMSPrecleanDenominator, | |
| 4665 "Bad convergence multiplier"); | |
| 4666 assert(CMSPrecleanThreshold >= 100, | |
| 4667 "Unreasonably low CMSPrecleanThreshold"); | |
| 4668 | |
| 4669 size_t numIter, cumNumCards, lastNumCards, curNumCards; | |
| 4670 for (numIter = 0, cumNumCards = lastNumCards = curNumCards = 0; | |
| 4671 numIter < CMSPrecleanIter; | |
| 4672 numIter++, lastNumCards = curNumCards, cumNumCards += curNumCards) { | |
| 4673 curNumCards = preclean_mod_union_table(_cmsGen, &smoac_cl); | |
| 4674 if (Verbose && PrintGCDetails) { | |
| 4675 gclog_or_tty->print(" (modUnionTable: %d cards)", curNumCards); | |
| 4676 } | |
| 4677 // Either there are very few dirty cards, so re-mark | |
| 4678 // pause will be small anyway, or our pre-cleaning isn't | |
| 4679 // that much faster than the rate at which cards are being | |
| 4680 // dirtied, so we might as well stop and re-mark since | |
| 4681 // precleaning won't improve our re-mark time by much. | |
| 4682 if (curNumCards <= CMSPrecleanThreshold || | |
| 4683 (numIter > 0 && | |
| 4684 (curNumCards * CMSPrecleanDenominator > | |
| 4685 lastNumCards * CMSPrecleanNumerator))) { | |
| 4686 numIter++; | |
| 4687 cumNumCards += curNumCards; | |
| 4688 break; | |
| 4689 } | |
| 4690 } | |
|
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4691 |
|
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4692 preclean_klasses(&mrias_cl, _cmsGen->freelistLock()); |
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4693 |
| 0 | 4694 curNumCards = preclean_card_table(_cmsGen, &smoac_cl); |
| 4695 cumNumCards += curNumCards; | |
| 4696 if (PrintGCDetails && PrintCMSStatistics != 0) { | |
| 4697 gclog_or_tty->print_cr(" (cardTable: %d cards, re-scanned %d cards, %d iterations)", | |
| 4698 curNumCards, cumNumCards, numIter); | |
| 4699 } | |
| 4700 return cumNumCards; // as a measure of useful work done | |
| 4701 } | |
| 4702 | |
| 4703 // PRECLEANING NOTES: | |
| 4704 // Precleaning involves: | |
| 4705 // . reading the bits of the modUnionTable and clearing the set bits. | |
| 4706 // . For the cards corresponding to the set bits, we scan the | |
| 4707 // objects on those cards. This means we need the free_list_lock | |
| 4708 // so that we can safely iterate over the CMS space when scanning | |
| 4709 // for oops. | |
| 4710 // . When we scan the objects, we'll be both reading and setting | |
| 4711 // marks in the marking bit map, so we'll need the marking bit map. | |
| 4712 // . For protecting _collector_state transitions, we take the CGC_lock. | |
| 4713 // Note that any races in the reading of of card table entries by the | |
| 4714 // CMS thread on the one hand and the clearing of those entries by the | |
| 4715 // VM thread or the setting of those entries by the mutator threads on the | |
| 4716 // other are quite benign. However, for efficiency it makes sense to keep | |
| 4717 // the VM thread from racing with the CMS thread while the latter is | |
| 4718 // dirty card info to the modUnionTable. We therefore also use the | |
| 4719 // CGC_lock to protect the reading of the card table and the mod union | |
| 4720 // table by the CM thread. | |
| 4721 // . We run concurrently with mutator updates, so scanning | |
| 4722 // needs to be done carefully -- we should not try to scan | |
| 4723 // potentially uninitialized objects. | |
| 4724 // | |
| 4725 // Locking strategy: While holding the CGC_lock, we scan over and | |
| 4726 // reset a maximal dirty range of the mod union / card tables, then lock | |
| 4727 // the free_list_lock and bitmap lock to do a full marking, then | |
| 4728 // release these locks; and repeat the cycle. This allows for a | |
| 4729 // certain amount of fairness in the sharing of these locks between | |
| 4730 // the CMS collector on the one hand, and the VM thread and the | |
| 4731 // mutators on the other. | |
| 4732 | |
| 4733 // NOTE: preclean_mod_union_table() and preclean_card_table() | |
| 4734 // further below are largely identical; if you need to modify | |
| 4735 // one of these methods, please check the other method too. | |
| 4736 | |
| 4737 size_t CMSCollector::preclean_mod_union_table( | |
| 4738 ConcurrentMarkSweepGeneration* gen, | |
| 4739 ScanMarkedObjectsAgainCarefullyClosure* cl) { | |
| 4740 verify_work_stacks_empty(); | |
| 4741 verify_overflow_empty(); | |
| 4742 | |
| 4743 // strategy: starting with the first card, accumulate contiguous | |
| 4744 // ranges of dirty cards; clear these cards, then scan the region | |
| 4745 // covered by these cards. | |
| 4746 | |
| 4747 // Since all of the MUT is committed ahead, we can just use | |
| 4748 // that, in case the generations expand while we are precleaning. | |
| 4749 // It might also be fine to just use the committed part of the | |
| 4750 // generation, but we might potentially miss cards when the | |
| 4751 // generation is rapidly expanding while we are in the midst | |
| 4752 // of precleaning. | |
| 4753 HeapWord* startAddr = gen->reserved().start(); | |
| 4754 HeapWord* endAddr = gen->reserved().end(); | |
| 4755 | |
| 4756 cl->setFreelistLock(gen->freelistLock()); // needed for yielding | |
| 4757 | |
| 4758 size_t numDirtyCards, cumNumDirtyCards; | |
| 4759 HeapWord *nextAddr, *lastAddr; | |
| 4760 for (cumNumDirtyCards = numDirtyCards = 0, | |
| 4761 nextAddr = lastAddr = startAddr; | |
| 4762 nextAddr < endAddr; | |
| 4763 nextAddr = lastAddr, cumNumDirtyCards += numDirtyCards) { | |
| 4764 | |
| 4765 ResourceMark rm; | |
| 4766 HandleMark hm; | |
| 4767 | |
| 4768 MemRegion dirtyRegion; | |
| 4769 { | |
| 4770 stopTimer(); | |
| 935 | 4771 // Potential yield point |
| 0 | 4772 CMSTokenSync ts(true); |
| 4773 startTimer(); | |
| 4774 sample_eden(); | |
| 4775 // Get dirty region starting at nextOffset (inclusive), | |
| 4776 // simultaneously clearing it. | |
| 4777 dirtyRegion = | |
| 4778 _modUnionTable.getAndClearMarkedRegion(nextAddr, endAddr); | |
| 4779 assert(dirtyRegion.start() >= nextAddr, | |
| 4780 "returned region inconsistent?"); | |
| 4781 } | |
| 4782 // Remember where the next search should begin. | |
| 4783 // The returned region (if non-empty) is a right open interval, | |
| 4784 // so lastOffset is obtained from the right end of that | |
| 4785 // interval. | |
| 4786 lastAddr = dirtyRegion.end(); | |
| 4787 // Should do something more transparent and less hacky XXX | |
| 4788 numDirtyCards = | |
| 4789 _modUnionTable.heapWordDiffToOffsetDiff(dirtyRegion.word_size()); | |
| 4790 | |
| 4791 // We'll scan the cards in the dirty region (with periodic | |
| 4792 // yields for foreground GC as needed). | |
| 4793 if (!dirtyRegion.is_empty()) { | |
| 4794 assert(numDirtyCards > 0, "consistency check"); | |
| 4795 HeapWord* stop_point = NULL; | |
|
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4796 stopTimer(); |
| 935 | 4797 // Potential yield point |
|
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4798 CMSTokenSyncWithLocks ts(true, gen->freelistLock(), |
|
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|
4799 bitMapLock()); |
|
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|
4800 startTimer(); |
| 0 | 4801 { |
| 4802 verify_work_stacks_empty(); | |
| 4803 verify_overflow_empty(); | |
| 4804 sample_eden(); | |
| 4805 stop_point = | |
| 4806 gen->cmsSpace()->object_iterate_careful_m(dirtyRegion, cl); | |
| 4807 } | |
| 4808 if (stop_point != NULL) { | |
| 4809 // The careful iteration stopped early either because it found an | |
| 4810 // uninitialized object, or because we were in the midst of an | |
| 4811 // "abortable preclean", which should now be aborted. Redirty | |
| 4812 // the bits corresponding to the partially-scanned or unscanned | |
| 4813 // cards. We'll either restart at the next block boundary or | |
| 4814 // abort the preclean. | |
|
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4815 assert((_collectorState == AbortablePreclean && should_abort_preclean()), |
|
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|
4816 "Should only be AbortablePreclean."); |
| 0 | 4817 _modUnionTable.mark_range(MemRegion(stop_point, dirtyRegion.end())); |
| 4818 if (should_abort_preclean()) { | |
| 4819 break; // out of preclean loop | |
| 4820 } else { | |
| 4821 // Compute the next address at which preclean should pick up; | |
| 4822 // might need bitMapLock in order to read P-bits. | |
| 4823 lastAddr = next_card_start_after_block(stop_point); | |
| 4824 } | |
| 4825 } | |
| 4826 } else { | |
| 4827 assert(lastAddr == endAddr, "consistency check"); | |
| 4828 assert(numDirtyCards == 0, "consistency check"); | |
| 4829 break; | |
| 4830 } | |
| 4831 } | |
| 4832 verify_work_stacks_empty(); | |
| 4833 verify_overflow_empty(); | |
| 4834 return cumNumDirtyCards; | |
| 4835 } | |
| 4836 | |
| 4837 // NOTE: preclean_mod_union_table() above and preclean_card_table() | |
| 4838 // below are largely identical; if you need to modify | |
| 4839 // one of these methods, please check the other method too. | |
| 4840 | |
| 4841 size_t CMSCollector::preclean_card_table(ConcurrentMarkSweepGeneration* gen, | |
| 4842 ScanMarkedObjectsAgainCarefullyClosure* cl) { | |
| 4843 // strategy: it's similar to precleamModUnionTable above, in that | |
| 4844 // we accumulate contiguous ranges of dirty cards, mark these cards | |
| 4845 // precleaned, then scan the region covered by these cards. | |
| 4846 HeapWord* endAddr = (HeapWord*)(gen->_virtual_space.high()); | |
| 4847 HeapWord* startAddr = (HeapWord*)(gen->_virtual_space.low()); | |
| 4848 | |
| 4849 cl->setFreelistLock(gen->freelistLock()); // needed for yielding | |
| 4850 | |
| 4851 size_t numDirtyCards, cumNumDirtyCards; | |
| 4852 HeapWord *lastAddr, *nextAddr; | |
| 4853 | |
| 4854 for (cumNumDirtyCards = numDirtyCards = 0, | |
| 4855 nextAddr = lastAddr = startAddr; | |
| 4856 nextAddr < endAddr; | |
| 4857 nextAddr = lastAddr, cumNumDirtyCards += numDirtyCards) { | |
| 4858 | |
| 4859 ResourceMark rm; | |
| 4860 HandleMark hm; | |
| 4861 | |
| 4862 MemRegion dirtyRegion; | |
| 4863 { | |
| 4864 // See comments in "Precleaning notes" above on why we | |
| 4865 // do this locking. XXX Could the locking overheads be | |
| 4866 // too high when dirty cards are sparse? [I don't think so.] | |
| 4867 stopTimer(); | |
| 4868 CMSTokenSync x(true); // is cms thread | |
| 4869 startTimer(); | |
| 4870 sample_eden(); | |
| 4871 // Get and clear dirty region from card table | |
|
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4872 dirtyRegion = _ct->ct_bs()->dirty_card_range_after_reset( |
|
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|
4873 MemRegion(nextAddr, endAddr), |
|
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|
4874 true, |
|
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|
4875 CardTableModRefBS::precleaned_card_val()); |
|
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4876 |
| 0 | 4877 assert(dirtyRegion.start() >= nextAddr, |
| 4878 "returned region inconsistent?"); | |
| 4879 } | |
| 4880 lastAddr = dirtyRegion.end(); | |
| 4881 numDirtyCards = | |
| 4882 dirtyRegion.word_size()/CardTableModRefBS::card_size_in_words; | |
| 4883 | |
| 4884 if (!dirtyRegion.is_empty()) { | |
| 4885 stopTimer(); | |
| 4886 CMSTokenSyncWithLocks ts(true, gen->freelistLock(), bitMapLock()); | |
| 4887 startTimer(); | |
| 4888 sample_eden(); | |
| 4889 verify_work_stacks_empty(); | |
| 4890 verify_overflow_empty(); | |
| 4891 HeapWord* stop_point = | |
| 4892 gen->cmsSpace()->object_iterate_careful_m(dirtyRegion, cl); | |
| 4893 if (stop_point != NULL) { | |
|
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4894 assert((_collectorState == AbortablePreclean && should_abort_preclean()), |
|
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|
4895 "Should only be AbortablePreclean."); |
| 0 | 4896 _ct->ct_bs()->invalidate(MemRegion(stop_point, dirtyRegion.end())); |
| 4897 if (should_abort_preclean()) { | |
| 4898 break; // out of preclean loop | |
| 4899 } else { | |
| 4900 // Compute the next address at which preclean should pick up. | |
| 4901 lastAddr = next_card_start_after_block(stop_point); | |
| 4902 } | |
| 4903 } | |
| 4904 } else { | |
| 4905 break; | |
| 4906 } | |
| 4907 } | |
| 4908 verify_work_stacks_empty(); | |
| 4909 verify_overflow_empty(); | |
| 4910 return cumNumDirtyCards; | |
| 4911 } | |
| 4912 | |
|
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4913 class PrecleanKlassClosure : public KlassClosure { |
|
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4914 CMKlassClosure _cm_klass_closure; |
|
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4915 public: |
|
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|
4916 PrecleanKlassClosure(OopClosure* oop_closure) : _cm_klass_closure(oop_closure) {} |
|
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4917 void do_klass(Klass* k) { |
|
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4918 if (k->has_accumulated_modified_oops()) { |
|
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4919 k->clear_accumulated_modified_oops(); |
|
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4920 |
|
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4921 _cm_klass_closure.do_klass(k); |
|
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4922 } |
|
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|
4923 } |
|
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|
4924 }; |
|
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4925 |
|
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4926 // The freelist lock is needed to prevent asserts, is it really needed? |
|
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4927 void CMSCollector::preclean_klasses(MarkRefsIntoAndScanClosure* cl, Mutex* freelistLock) { |
|
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4928 |
|
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4929 cl->set_freelistLock(freelistLock); |
|
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4930 |
|
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|
4931 CMSTokenSyncWithLocks ts(true, freelistLock, bitMapLock()); |
|
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4932 |
|
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|
4933 // SSS: Add equivalent to ScanMarkedObjectsAgainCarefullyClosure::do_yield_check and should_abort_preclean? |
|
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4934 // SSS: We should probably check if precleaning should be aborted, at suitable intervals? |
|
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4935 PrecleanKlassClosure preclean_klass_closure(cl); |
|
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4936 ClassLoaderDataGraph::classes_do(&preclean_klass_closure); |
|
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4937 |
|
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4938 verify_work_stacks_empty(); |
|
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4939 verify_overflow_empty(); |
|
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|
4940 } |
|
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|
4941 |
| 0 | 4942 void CMSCollector::checkpointRootsFinal(bool asynch, |
| 4943 bool clear_all_soft_refs, bool init_mark_was_synchronous) { | |
| 4944 assert(_collectorState == FinalMarking, "incorrect state transition?"); | |
| 4945 check_correct_thread_executing(); | |
| 4946 // world is stopped at this checkpoint | |
| 4947 assert(SafepointSynchronize::is_at_safepoint(), | |
| 4948 "world should be stopped"); | |
|
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|
4949 TraceCMSMemoryManagerStats tms(_collectorState,GenCollectedHeap::heap()->gc_cause()); |
|
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|
4950 |
| 0 | 4951 verify_work_stacks_empty(); |
| 4952 verify_overflow_empty(); | |
| 4953 | |
| 4954 SpecializationStats::clear(); | |
| 4955 if (PrintGCDetails) { | |
| 4956 gclog_or_tty->print("[YG occupancy: "SIZE_FORMAT" K ("SIZE_FORMAT" K)]", | |
| 4957 _young_gen->used() / K, | |
| 4958 _young_gen->capacity() / K); | |
| 4959 } | |
| 4960 if (asynch) { | |
| 4961 if (CMSScavengeBeforeRemark) { | |
| 4962 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 4963 // Temporarily set flag to false, GCH->do_collection will | |
| 4964 // expect it to be false and set to true | |
| 4965 FlagSetting fl(gch->_is_gc_active, false); | |
| 10405 | 4966 NOT_PRODUCT(GCTraceTime t("Scavenge-Before-Remark", |
| 4967 PrintGCDetails && Verbose, true, _gc_timer_cm);) | |
| 0 | 4968 int level = _cmsGen->level() - 1; |
| 4969 if (level >= 0) { | |
| 4970 gch->do_collection(true, // full (i.e. force, see below) | |
| 4971 false, // !clear_all_soft_refs | |
| 4972 0, // size | |
| 4973 false, // is_tlab | |
| 4974 level // max_level | |
| 4975 ); | |
| 4976 } | |
| 4977 } | |
| 4978 FreelistLocker x(this); | |
| 4979 MutexLockerEx y(bitMapLock(), | |
| 4980 Mutex::_no_safepoint_check_flag); | |
| 4981 assert(!init_mark_was_synchronous, "but that's impossible!"); | |
| 4982 checkpointRootsFinalWork(asynch, clear_all_soft_refs, false); | |
| 4983 } else { | |
| 4984 // already have all the locks | |
| 4985 checkpointRootsFinalWork(asynch, clear_all_soft_refs, | |
| 4986 init_mark_was_synchronous); | |
| 4987 } | |
| 4988 verify_work_stacks_empty(); | |
| 4989 verify_overflow_empty(); | |
| 4990 SpecializationStats::print(); | |
| 4991 } | |
| 4992 | |
| 4993 void CMSCollector::checkpointRootsFinalWork(bool asynch, | |
| 4994 bool clear_all_soft_refs, bool init_mark_was_synchronous) { | |
| 4995 | |
| 10405 | 4996 NOT_PRODUCT(GCTraceTime tr("checkpointRootsFinalWork", PrintGCDetails, false, _gc_timer_cm);) |
| 0 | 4997 |
| 4998 assert(haveFreelistLocks(), "must have free list locks"); | |
| 4999 assert_lock_strong(bitMapLock()); | |
| 5000 | |
| 5001 if (UseAdaptiveSizePolicy) { | |
| 5002 size_policy()->checkpoint_roots_final_begin(); | |
| 5003 } | |
| 5004 | |
| 5005 ResourceMark rm; | |
| 5006 HandleMark hm; | |
| 5007 | |
| 5008 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 5009 | |
|
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|
5010 if (should_unload_classes()) { |
| 0 | 5011 CodeCache::gc_prologue(); |
| 5012 } | |
| 5013 assert(haveFreelistLocks(), "must have free list locks"); | |
| 5014 assert_lock_strong(bitMapLock()); | |
| 5015 | |
| 5016 if (!init_mark_was_synchronous) { | |
| 5017 // We might assume that we need not fill TLAB's when | |
| 5018 // CMSScavengeBeforeRemark is set, because we may have just done | |
| 5019 // a scavenge which would have filled all TLAB's -- and besides | |
| 5020 // Eden would be empty. This however may not always be the case -- | |
| 5021 // for instance although we asked for a scavenge, it may not have | |
| 5022 // happened because of a JNI critical section. We probably need | |
| 5023 // a policy for deciding whether we can in that case wait until | |
| 5024 // the critical section releases and then do the remark following | |
| 5025 // the scavenge, and skip it here. In the absence of that policy, | |
| 5026 // or of an indication of whether the scavenge did indeed occur, | |
| 5027 // we cannot rely on TLAB's having been filled and must do | |
| 5028 // so here just in case a scavenge did not happen. | |
| 5029 gch->ensure_parsability(false); // fill TLAB's, but no need to retire them | |
| 5030 // Update the saved marks which may affect the root scans. | |
| 5031 gch->save_marks(); | |
| 5032 | |
| 5033 { | |
| 5034 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact;) | |
| 5035 | |
| 5036 // Note on the role of the mod union table: | |
| 5037 // Since the marker in "markFromRoots" marks concurrently with | |
| 5038 // mutators, it is possible for some reachable objects not to have been | |
| 5039 // scanned. For instance, an only reference to an object A was | |
| 5040 // placed in object B after the marker scanned B. Unless B is rescanned, | |
| 5041 // A would be collected. Such updates to references in marked objects | |
| 5042 // are detected via the mod union table which is the set of all cards | |
| 5043 // dirtied since the first checkpoint in this GC cycle and prior to | |
| 5044 // the most recent young generation GC, minus those cleaned up by the | |
| 5045 // concurrent precleaning. | |
|
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|
5046 if (CMSParallelRemarkEnabled && CollectedHeap::use_parallel_gc_threads()) { |
| 10405 | 5047 GCTraceTime t("Rescan (parallel) ", PrintGCDetails, false, _gc_timer_cm); |
| 0 | 5048 do_remark_parallel(); |
| 5049 } else { | |
| 10405 | 5050 GCTraceTime t("Rescan (non-parallel) ", PrintGCDetails, false, |
| 5051 _gc_timer_cm); | |
| 0 | 5052 do_remark_non_parallel(); |
| 5053 } | |
| 5054 } | |
| 5055 } else { | |
| 5056 assert(!asynch, "Can't have init_mark_was_synchronous in asynch mode"); | |
| 5057 // The initial mark was stop-world, so there's no rescanning to | |
| 5058 // do; go straight on to the next step below. | |
| 5059 } | |
| 5060 verify_work_stacks_empty(); | |
| 5061 verify_overflow_empty(); | |
| 5062 | |
| 5063 { | |
| 10405 | 5064 NOT_PRODUCT(GCTraceTime ts("refProcessingWork", PrintGCDetails, false, _gc_timer_cm);) |
| 0 | 5065 refProcessingWork(asynch, clear_all_soft_refs); |
| 5066 } | |
| 5067 verify_work_stacks_empty(); | |
| 5068 verify_overflow_empty(); | |
| 5069 | |
|
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|
5070 if (should_unload_classes()) { |
| 0 | 5071 CodeCache::gc_epilogue(); |
| 5072 } | |
|
2147
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|
5073 JvmtiExport::gc_epilogue(); |
| 0 | 5074 |
| 5075 // If we encountered any (marking stack / work queue) overflow | |
| 5076 // events during the current CMS cycle, take appropriate | |
| 5077 // remedial measures, where possible, so as to try and avoid | |
| 5078 // recurrence of that condition. | |
| 5079 assert(_markStack.isEmpty(), "No grey objects"); | |
| 5080 size_t ser_ovflw = _ser_pmc_remark_ovflw + _ser_pmc_preclean_ovflw + | |
|
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|
5081 _ser_kac_ovflw + _ser_kac_preclean_ovflw; |
| 0 | 5082 if (ser_ovflw > 0) { |
| 5083 if (PrintCMSStatistics != 0) { | |
| 5084 gclog_or_tty->print_cr("Marking stack overflow (benign) " | |
|
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|
5085 "(pmc_pc="SIZE_FORMAT", pmc_rm="SIZE_FORMAT", kac="SIZE_FORMAT |
|
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|
5086 ", kac_preclean="SIZE_FORMAT")", |
| 0 | 5087 _ser_pmc_preclean_ovflw, _ser_pmc_remark_ovflw, |
|
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|
5088 _ser_kac_ovflw, _ser_kac_preclean_ovflw); |
| 0 | 5089 } |
| 5090 _markStack.expand(); | |
| 5091 _ser_pmc_remark_ovflw = 0; | |
| 5092 _ser_pmc_preclean_ovflw = 0; | |
|
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|
5093 _ser_kac_preclean_ovflw = 0; |
| 0 | 5094 _ser_kac_ovflw = 0; |
| 5095 } | |
| 5096 if (_par_pmc_remark_ovflw > 0 || _par_kac_ovflw > 0) { | |
| 5097 if (PrintCMSStatistics != 0) { | |
| 5098 gclog_or_tty->print_cr("Work queue overflow (benign) " | |
| 5099 "(pmc_rm="SIZE_FORMAT", kac="SIZE_FORMAT")", | |
| 5100 _par_pmc_remark_ovflw, _par_kac_ovflw); | |
| 5101 } | |
| 5102 _par_pmc_remark_ovflw = 0; | |
| 5103 _par_kac_ovflw = 0; | |
| 5104 } | |
| 5105 if (PrintCMSStatistics != 0) { | |
| 5106 if (_markStack._hit_limit > 0) { | |
| 5107 gclog_or_tty->print_cr(" (benign) Hit max stack size limit ("SIZE_FORMAT")", | |
| 5108 _markStack._hit_limit); | |
| 5109 } | |
| 5110 if (_markStack._failed_double > 0) { | |
| 5111 gclog_or_tty->print_cr(" (benign) Failed stack doubling ("SIZE_FORMAT")," | |
| 5112 " current capacity "SIZE_FORMAT, | |
| 5113 _markStack._failed_double, | |
| 5114 _markStack.capacity()); | |
| 5115 } | |
| 5116 } | |
| 5117 _markStack._hit_limit = 0; | |
| 5118 _markStack._failed_double = 0; | |
| 5119 | |
| 5120 if ((VerifyAfterGC || VerifyDuringGC) && | |
| 5121 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
| 5122 verify_after_remark(); | |
| 5123 } | |
| 5124 | |
| 10405 | 5125 _gc_tracer_cm->report_object_count_after_gc(&_is_alive_closure); |
| 5126 | |
| 0 | 5127 // Change under the freelistLocks. |
| 5128 _collectorState = Sweeping; | |
| 5129 // Call isAllClear() under bitMapLock | |
|
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5130 assert(_modUnionTable.isAllClear(), |
|
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5131 "Should be clear by end of the final marking"); |
|
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5132 assert(_ct->klass_rem_set()->mod_union_is_clear(), |
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5133 "Should be clear by end of the final marking"); |
| 0 | 5134 if (UseAdaptiveSizePolicy) { |
| 5135 size_policy()->checkpoint_roots_final_end(gch->gc_cause()); | |
| 5136 } | |
| 5137 } | |
| 5138 | |
| 5139 // Parallel remark task | |
| 5140 class CMSParRemarkTask: public AbstractGangTask { | |
| 5141 CMSCollector* _collector; | |
| 5142 int _n_workers; | |
| 5143 CompactibleFreeListSpace* _cms_space; | |
| 5144 | |
| 5145 // The per-thread work queues, available here for stealing. | |
| 5146 OopTaskQueueSet* _task_queues; | |
| 5147 ParallelTaskTerminator _term; | |
| 5148 | |
| 5149 public: | |
|
4095
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5150 // A value of 0 passed to n_workers will cause the number of |
|
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5151 // workers to be taken from the active workers in the work gang. |
| 0 | 5152 CMSParRemarkTask(CMSCollector* collector, |
| 5153 CompactibleFreeListSpace* cms_space, | |
|
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5154 int n_workers, FlexibleWorkGang* workers, |
| 0 | 5155 OopTaskQueueSet* task_queues): |
| 5156 AbstractGangTask("Rescan roots and grey objects in parallel"), | |
| 5157 _collector(collector), | |
|
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5158 _cms_space(cms_space), |
| 0 | 5159 _n_workers(n_workers), |
| 5160 _task_queues(task_queues), | |
|
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5161 _term(n_workers, task_queues) { } |
| 0 | 5162 |
| 5163 OopTaskQueueSet* task_queues() { return _task_queues; } | |
| 5164 | |
| 5165 OopTaskQueue* work_queue(int i) { return task_queues()->queue(i); } | |
| 5166 | |
| 5167 ParallelTaskTerminator* terminator() { return &_term; } | |
|
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5168 int n_workers() { return _n_workers; } |
| 0 | 5169 |
|
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5170 void work(uint worker_id); |
| 0 | 5171 |
| 5172 private: | |
| 5173 // Work method in support of parallel rescan ... of young gen spaces | |
| 5174 void do_young_space_rescan(int i, Par_MarkRefsIntoAndScanClosure* cl, | |
| 5175 ContiguousSpace* space, | |
| 5176 HeapWord** chunk_array, size_t chunk_top); | |
| 5177 | |
| 5178 // ... of dirty cards in old space | |
| 5179 void do_dirty_card_rescan_tasks(CompactibleFreeListSpace* sp, int i, | |
| 5180 Par_MarkRefsIntoAndScanClosure* cl); | |
| 5181 | |
| 5182 // ... work stealing for the above | |
| 5183 void do_work_steal(int i, Par_MarkRefsIntoAndScanClosure* cl, int* seed); | |
| 5184 }; | |
| 5185 | |
|
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5186 class RemarkKlassClosure : public KlassClosure { |
|
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5187 CMKlassClosure _cm_klass_closure; |
|
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5188 public: |
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5189 RemarkKlassClosure(OopClosure* oop_closure) : _cm_klass_closure(oop_closure) {} |
|
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5190 void do_klass(Klass* k) { |
|
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5191 // Check if we have modified any oops in the Klass during the concurrent marking. |
|
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5192 if (k->has_accumulated_modified_oops()) { |
|
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5193 k->clear_accumulated_modified_oops(); |
|
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5194 |
|
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5195 // We could have transfered the current modified marks to the accumulated marks, |
|
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5196 // like we do with the Card Table to Mod Union Table. But it's not really necessary. |
|
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|
5197 } else if (k->has_modified_oops()) { |
|
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5198 // Don't clear anything, this info is needed by the next young collection. |
|
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5199 } else { |
|
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5200 // No modified oops in the Klass. |
|
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5201 return; |
|
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|
5202 } |
|
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|
5203 |
|
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5204 // The klass has modified fields, need to scan the klass. |
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5205 _cm_klass_closure.do_klass(k); |
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5206 } |
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5207 }; |
|
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|
5208 |
|
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|
5209 // work_queue(i) is passed to the closure |
|
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|
5210 // Par_MarkRefsIntoAndScanClosure. The "i" parameter |
|
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5211 // also is passed to do_dirty_card_rescan_tasks() and to |
|
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5212 // do_work_steal() to select the i-th task_queue. |
|
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5213 |
|
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|
5214 void CMSParRemarkTask::work(uint worker_id) { |
| 0 | 5215 elapsedTimer _timer; |
| 5216 ResourceMark rm; | |
| 5217 HandleMark hm; | |
| 5218 | |
| 5219 // ---------- rescan from roots -------------- | |
| 5220 _timer.start(); | |
| 5221 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 5222 Par_MarkRefsIntoAndScanClosure par_mrias_cl(_collector, | |
| 5223 _collector->_span, _collector->ref_processor(), | |
| 5224 &(_collector->_markBitMap), | |
|
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5225 work_queue(worker_id)); |
| 0 | 5226 |
| 5227 // Rescan young gen roots first since these are likely | |
| 5228 // coarsely partitioned and may, on that account, constitute | |
| 5229 // the critical path; thus, it's best to start off that | |
| 5230 // work first. | |
| 5231 // ---------- young gen roots -------------- | |
| 5232 { | |
| 5233 DefNewGeneration* dng = _collector->_young_gen->as_DefNewGeneration(); | |
| 5234 EdenSpace* eden_space = dng->eden(); | |
| 5235 ContiguousSpace* from_space = dng->from(); | |
| 5236 ContiguousSpace* to_space = dng->to(); | |
| 5237 | |
| 5238 HeapWord** eca = _collector->_eden_chunk_array; | |
| 5239 size_t ect = _collector->_eden_chunk_index; | |
| 5240 HeapWord** sca = _collector->_survivor_chunk_array; | |
| 5241 size_t sct = _collector->_survivor_chunk_index; | |
| 5242 | |
| 5243 assert(ect <= _collector->_eden_chunk_capacity, "out of bounds"); | |
| 5244 assert(sct <= _collector->_survivor_chunk_capacity, "out of bounds"); | |
| 5245 | |
|
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|
5246 do_young_space_rescan(worker_id, &par_mrias_cl, to_space, NULL, 0); |
|
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|
5247 do_young_space_rescan(worker_id, &par_mrias_cl, from_space, sca, sct); |
|
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|
5248 do_young_space_rescan(worker_id, &par_mrias_cl, eden_space, eca, ect); |
| 0 | 5249 |
| 5250 _timer.stop(); | |
| 5251 if (PrintCMSStatistics != 0) { | |
| 5252 gclog_or_tty->print_cr( | |
| 5253 "Finished young gen rescan work in %dth thread: %3.3f sec", | |
|
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|
5254 worker_id, _timer.seconds()); |
| 0 | 5255 } |
| 5256 } | |
| 5257 | |
| 5258 // ---------- remaining roots -------------- | |
| 5259 _timer.reset(); | |
| 5260 _timer.start(); | |
| 5261 gch->gen_process_strong_roots(_collector->_cmsGen->level(), | |
| 5262 false, // yg was scanned above | |
|
989
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|
5263 false, // this is parallel code |
|
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|
5264 false, // not scavenging |
| 0 | 5265 SharedHeap::ScanningOption(_collector->CMSCollector::roots_scanning_options()), |
|
989
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|
5266 &par_mrias_cl, |
|
148e5441d916
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jrose
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|
5267 true, // walk all of code cache if (so & SO_CodeCache) |
|
6725
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|
5268 NULL, |
|
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|
5269 NULL); // The dirty klasses will be handled below |
|
989
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diff
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|
5270 assert(_collector->should_unload_classes() |
|
148e5441d916
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|
5271 || (_collector->CMSCollector::roots_scanning_options() & SharedHeap::SO_CodeCache), |
|
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jrose
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|
5272 "if we didn't scan the code cache, we have to be ready to drop nmethods with expired weak oops"); |
| 0 | 5273 _timer.stop(); |
| 5274 if (PrintCMSStatistics != 0) { | |
| 5275 gclog_or_tty->print_cr( | |
| 5276 "Finished remaining root rescan work in %dth thread: %3.3f sec", | |
|
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|
5277 worker_id, _timer.seconds()); |
| 0 | 5278 } |
| 5279 | |
|
6725
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|
5280 // ---------- unhandled CLD scanning ---------- |
|
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|
5281 if (worker_id == 0) { // Single threaded at the moment. |
|
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|
5282 _timer.reset(); |
|
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|
5283 _timer.start(); |
|
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|
5284 |
|
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|
5285 // Scan all new class loader data objects and new dependencies that were |
|
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|
5286 // introduced during concurrent marking. |
|
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|
5287 ResourceMark rm; |
|
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|
5288 GrowableArray<ClassLoaderData*>* array = ClassLoaderDataGraph::new_clds(); |
|
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|
5289 for (int i = 0; i < array->length(); i++) { |
|
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|
5290 par_mrias_cl.do_class_loader_data(array->at(i)); |
|
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|
5291 } |
|
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|
5292 |
|
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|
5293 // We don't need to keep track of new CLDs anymore. |
|
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|
5294 ClassLoaderDataGraph::remember_new_clds(false); |
|
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|
5295 |
|
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|
5296 _timer.stop(); |
|
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|
5297 if (PrintCMSStatistics != 0) { |
|
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|
5298 gclog_or_tty->print_cr( |
|
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5299 "Finished unhandled CLD scanning work in %dth thread: %3.3f sec", |
|
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|
5300 worker_id, _timer.seconds()); |
|
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|
5301 } |
|
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|
5302 } |
|
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|
5303 |
|
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|
5304 // ---------- dirty klass scanning ---------- |
|
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|
5305 if (worker_id == 0) { // Single threaded at the moment. |
|
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|
5306 _timer.reset(); |
|
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|
5307 _timer.start(); |
|
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|
5308 |
|
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|
5309 // Scan all classes that was dirtied during the concurrent marking phase. |
|
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|
5310 RemarkKlassClosure remark_klass_closure(&par_mrias_cl); |
|
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|
5311 ClassLoaderDataGraph::classes_do(&remark_klass_closure); |
|
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|
5312 |
|
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|
5313 _timer.stop(); |
|
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5314 if (PrintCMSStatistics != 0) { |
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5315 gclog_or_tty->print_cr( |
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5316 "Finished dirty klass scanning work in %dth thread: %3.3f sec", |
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5317 worker_id, _timer.seconds()); |
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5318 } |
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5319 } |
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5320 |
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5321 // We might have added oops to ClassLoaderData::_handles during the |
|
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5322 // concurrent marking phase. These oops point to newly allocated objects |
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5323 // that are guaranteed to be kept alive. Either by the direct allocation |
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5324 // code, or when the young collector processes the strong roots. Hence, |
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5325 // we don't have to revisit the _handles block during the remark phase. |
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5326 |
| 0 | 5327 // ---------- rescan dirty cards ------------ |
| 5328 _timer.reset(); | |
| 5329 _timer.start(); | |
| 5330 | |
| 5331 // Do the rescan tasks for each of the two spaces | |
|
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5332 // (cms_space) in turn. |
|
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5333 // "worker_id" is passed to select the task_queue for "worker_id" |
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5334 do_dirty_card_rescan_tasks(_cms_space, worker_id, &par_mrias_cl); |
| 0 | 5335 _timer.stop(); |
| 5336 if (PrintCMSStatistics != 0) { | |
| 5337 gclog_or_tty->print_cr( | |
| 5338 "Finished dirty card rescan work in %dth thread: %3.3f sec", | |
|
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5339 worker_id, _timer.seconds()); |
| 0 | 5340 } |
| 5341 | |
| 5342 // ---------- steal work from other threads ... | |
| 5343 // ---------- ... and drain overflow list. | |
| 5344 _timer.reset(); | |
| 5345 _timer.start(); | |
|
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5346 do_work_steal(worker_id, &par_mrias_cl, _collector->hash_seed(worker_id)); |
| 0 | 5347 _timer.stop(); |
| 5348 if (PrintCMSStatistics != 0) { | |
| 5349 gclog_or_tty->print_cr( | |
| 5350 "Finished work stealing in %dth thread: %3.3f sec", | |
|
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5351 worker_id, _timer.seconds()); |
| 0 | 5352 } |
| 5353 } | |
| 5354 | |
|
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5355 // Note that parameter "i" is not used. |
| 0 | 5356 void |
| 5357 CMSParRemarkTask::do_young_space_rescan(int i, | |
| 5358 Par_MarkRefsIntoAndScanClosure* cl, ContiguousSpace* space, | |
| 5359 HeapWord** chunk_array, size_t chunk_top) { | |
| 5360 // Until all tasks completed: | |
| 5361 // . claim an unclaimed task | |
| 5362 // . compute region boundaries corresponding to task claimed | |
| 5363 // using chunk_array | |
| 5364 // . par_oop_iterate(cl) over that region | |
| 5365 | |
| 5366 ResourceMark rm; | |
| 5367 HandleMark hm; | |
| 5368 | |
| 5369 SequentialSubTasksDone* pst = space->par_seq_tasks(); | |
| 5370 assert(pst->valid(), "Uninitialized use?"); | |
| 5371 | |
|
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5372 uint nth_task = 0; |
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5373 uint n_tasks = pst->n_tasks(); |
| 0 | 5374 |
| 5375 HeapWord *start, *end; | |
| 5376 while (!pst->is_task_claimed(/* reference */ nth_task)) { | |
| 5377 // We claimed task # nth_task; compute its boundaries. | |
| 5378 if (chunk_top == 0) { // no samples were taken | |
| 5379 assert(nth_task == 0 && n_tasks == 1, "Can have only 1 EdenSpace task"); | |
| 5380 start = space->bottom(); | |
| 5381 end = space->top(); | |
| 5382 } else if (nth_task == 0) { | |
| 5383 start = space->bottom(); | |
| 5384 end = chunk_array[nth_task]; | |
|
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5385 } else if (nth_task < (uint)chunk_top) { |
| 0 | 5386 assert(nth_task >= 1, "Control point invariant"); |
| 5387 start = chunk_array[nth_task - 1]; | |
| 5388 end = chunk_array[nth_task]; | |
| 5389 } else { | |
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5390 assert(nth_task == (uint)chunk_top, "Control point invariant"); |
| 0 | 5391 start = chunk_array[chunk_top - 1]; |
| 5392 end = space->top(); | |
| 5393 } | |
| 5394 MemRegion mr(start, end); | |
| 5395 // Verify that mr is in space | |
| 5396 assert(mr.is_empty() || space->used_region().contains(mr), | |
| 5397 "Should be in space"); | |
| 5398 // Verify that "start" is an object boundary | |
| 5399 assert(mr.is_empty() || oop(mr.start())->is_oop(), | |
| 5400 "Should be an oop"); | |
| 5401 space->par_oop_iterate(mr, cl); | |
| 5402 } | |
| 5403 pst->all_tasks_completed(); | |
| 5404 } | |
| 5405 | |
| 5406 void | |
| 5407 CMSParRemarkTask::do_dirty_card_rescan_tasks( | |
| 5408 CompactibleFreeListSpace* sp, int i, | |
| 5409 Par_MarkRefsIntoAndScanClosure* cl) { | |
| 5410 // Until all tasks completed: | |
| 5411 // . claim an unclaimed task | |
| 5412 // . compute region boundaries corresponding to task claimed | |
| 5413 // . transfer dirty bits ct->mut for that region | |
| 5414 // . apply rescanclosure to dirty mut bits for that region | |
| 5415 | |
| 5416 ResourceMark rm; | |
| 5417 HandleMark hm; | |
| 5418 | |
| 5419 OopTaskQueue* work_q = work_queue(i); | |
| 5420 ModUnionClosure modUnionClosure(&(_collector->_modUnionTable)); | |
| 5421 // CAUTION! CAUTION! CAUTION! CAUTION! CAUTION! CAUTION! CAUTION! | |
| 5422 // CAUTION: This closure has state that persists across calls to | |
| 5423 // the work method dirty_range_iterate_clear() in that it has | |
| 5424 // imbedded in it a (subtype of) UpwardsObjectClosure. The | |
| 5425 // use of that state in the imbedded UpwardsObjectClosure instance | |
| 5426 // assumes that the cards are always iterated (even if in parallel | |
| 5427 // by several threads) in monotonically increasing order per each | |
| 5428 // thread. This is true of the implementation below which picks | |
| 5429 // card ranges (chunks) in monotonically increasing order globally | |
| 5430 // and, a-fortiori, in monotonically increasing order per thread | |
| 5431 // (the latter order being a subsequence of the former). | |
| 5432 // If the work code below is ever reorganized into a more chaotic | |
| 5433 // work-partitioning form than the current "sequential tasks" | |
| 5434 // paradigm, the use of that persistent state will have to be | |
| 5435 // revisited and modified appropriately. See also related | |
| 5436 // bug 4756801 work on which should examine this code to make | |
| 5437 // sure that the changes there do not run counter to the | |
| 5438 // assumptions made here and necessary for correctness and | |
| 5439 // efficiency. Note also that this code might yield inefficient | |
| 5440 // behaviour in the case of very large objects that span one or | |
| 5441 // more work chunks. Such objects would potentially be scanned | |
| 5442 // several times redundantly. Work on 4756801 should try and | |
| 5443 // address that performance anomaly if at all possible. XXX | |
| 5444 MemRegion full_span = _collector->_span; | |
| 5445 CMSBitMap* bm = &(_collector->_markBitMap); // shared | |
| 5446 MarkFromDirtyCardsClosure | |
| 5447 greyRescanClosure(_collector, full_span, // entire span of interest | |
|
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5448 sp, bm, work_q, cl); |
| 0 | 5449 |
| 5450 SequentialSubTasksDone* pst = sp->conc_par_seq_tasks(); | |
| 5451 assert(pst->valid(), "Uninitialized use?"); | |
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5452 uint nth_task = 0; |
| 0 | 5453 const int alignment = CardTableModRefBS::card_size * BitsPerWord; |
| 5454 MemRegion span = sp->used_region(); | |
| 5455 HeapWord* start_addr = span.start(); | |
| 5456 HeapWord* end_addr = (HeapWord*)round_to((intptr_t)span.end(), | |
| 5457 alignment); | |
| 5458 const size_t chunk_size = sp->rescan_task_size(); // in HeapWord units | |
| 5459 assert((HeapWord*)round_to((intptr_t)start_addr, alignment) == | |
| 5460 start_addr, "Check alignment"); | |
| 5461 assert((size_t)round_to((intptr_t)chunk_size, alignment) == | |
| 5462 chunk_size, "Check alignment"); | |
| 5463 | |
| 5464 while (!pst->is_task_claimed(/* reference */ nth_task)) { | |
| 5465 // Having claimed the nth_task, compute corresponding mem-region, | |
| 5466 // which is a-fortiori aligned correctly (i.e. at a MUT bopundary). | |
| 5467 // The alignment restriction ensures that we do not need any | |
| 5468 // synchronization with other gang-workers while setting or | |
| 5469 // clearing bits in thus chunk of the MUT. | |
| 5470 MemRegion this_span = MemRegion(start_addr + nth_task*chunk_size, | |
| 5471 start_addr + (nth_task+1)*chunk_size); | |
| 5472 // The last chunk's end might be way beyond end of the | |
| 5473 // used region. In that case pull back appropriately. | |
| 5474 if (this_span.end() > end_addr) { | |
| 5475 this_span.set_end(end_addr); | |
| 5476 assert(!this_span.is_empty(), "Program logic (calculation of n_tasks)"); | |
| 5477 } | |
| 5478 // Iterate over the dirty cards covering this chunk, marking them | |
| 5479 // precleaned, and setting the corresponding bits in the mod union | |
| 5480 // table. Since we have been careful to partition at Card and MUT-word | |
| 5481 // boundaries no synchronization is needed between parallel threads. | |
| 5482 _collector->_ct->ct_bs()->dirty_card_iterate(this_span, | |
| 5483 &modUnionClosure); | |
| 5484 | |
| 5485 // Having transferred these marks into the modUnionTable, | |
| 5486 // rescan the marked objects on the dirty cards in the modUnionTable. | |
| 5487 // Even if this is at a synchronous collection, the initial marking | |
| 5488 // may have been done during an asynchronous collection so there | |
| 5489 // may be dirty bits in the mod-union table. | |
| 5490 _collector->_modUnionTable.dirty_range_iterate_clear( | |
| 5491 this_span, &greyRescanClosure); | |
| 5492 _collector->_modUnionTable.verifyNoOneBitsInRange( | |
| 5493 this_span.start(), | |
| 5494 this_span.end()); | |
| 5495 } | |
| 5496 pst->all_tasks_completed(); // declare that i am done | |
| 5497 } | |
| 5498 | |
| 5499 // . see if we can share work_queues with ParNew? XXX | |
| 5500 void | |
| 5501 CMSParRemarkTask::do_work_steal(int i, Par_MarkRefsIntoAndScanClosure* cl, | |
| 5502 int* seed) { | |
| 5503 OopTaskQueue* work_q = work_queue(i); | |
| 5504 NOT_PRODUCT(int num_steals = 0;) | |
| 5505 oop obj_to_scan; | |
| 5506 CMSBitMap* bm = &(_collector->_markBitMap); | |
| 5507 | |
| 5508 while (true) { | |
| 5509 // Completely finish any left over work from (an) earlier round(s) | |
| 5510 cl->trim_queue(0); | |
|
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|
5511 size_t num_from_overflow_list = MIN2((size_t)(work_q->max_elems() - work_q->size())/4, |
|
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5512 (size_t)ParGCDesiredObjsFromOverflowList); |
| 0 | 5513 // Now check if there's any work in the overflow list |
|
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5514 // Passing ParallelGCThreads as the third parameter, no_of_gc_threads, |
|
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5515 // only affects the number of attempts made to get work from the |
|
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5516 // overflow list and does not affect the number of workers. Just |
|
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5517 // pass ParallelGCThreads so this behavior is unchanged. |
| 0 | 5518 if (_collector->par_take_from_overflow_list(num_from_overflow_list, |
|
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|
5519 work_q, |
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|
5520 ParallelGCThreads)) { |
| 0 | 5521 // found something in global overflow list; |
| 5522 // not yet ready to go stealing work from others. | |
| 5523 // We'd like to assert(work_q->size() != 0, ...) | |
| 5524 // because we just took work from the overflow list, | |
| 5525 // but of course we can't since all of that could have | |
| 5526 // been already stolen from us. | |
| 5527 // "He giveth and He taketh away." | |
| 5528 continue; | |
| 5529 } | |
| 5530 // Verify that we have no work before we resort to stealing | |
| 5531 assert(work_q->size() == 0, "Have work, shouldn't steal"); | |
| 5532 // Try to steal from other queues that have work | |
| 5533 if (task_queues()->steal(i, seed, /* reference */ obj_to_scan)) { | |
| 5534 NOT_PRODUCT(num_steals++;) | |
| 5535 assert(obj_to_scan->is_oop(), "Oops, not an oop!"); | |
| 5536 assert(bm->isMarked((HeapWord*)obj_to_scan), "Stole an unmarked oop?"); | |
| 5537 // Do scanning work | |
| 5538 obj_to_scan->oop_iterate(cl); | |
| 5539 // Loop around, finish this work, and try to steal some more | |
| 5540 } else if (terminator()->offer_termination()) { | |
| 5541 break; // nirvana from the infinite cycle | |
| 5542 } | |
| 5543 } | |
| 5544 NOT_PRODUCT( | |
| 5545 if (PrintCMSStatistics != 0) { | |
| 5546 gclog_or_tty->print("\n\t(%d: stole %d oops)", i, num_steals); | |
| 5547 } | |
| 5548 ) | |
| 5549 assert(work_q->size() == 0 && _collector->overflow_list_is_empty(), | |
| 5550 "Else our work is not yet done"); | |
| 5551 } | |
| 5552 | |
| 5553 // Return a thread-local PLAB recording array, as appropriate. | |
| 5554 void* CMSCollector::get_data_recorder(int thr_num) { | |
| 5555 if (_survivor_plab_array != NULL && | |
| 5556 (CMSPLABRecordAlways || | |
| 5557 (_collectorState > Marking && _collectorState < FinalMarking))) { | |
| 5558 assert(thr_num < (int)ParallelGCThreads, "thr_num is out of bounds"); | |
| 5559 ChunkArray* ca = &_survivor_plab_array[thr_num]; | |
| 5560 ca->reset(); // clear it so that fresh data is recorded | |
| 5561 return (void*) ca; | |
| 5562 } else { | |
| 5563 return NULL; | |
| 5564 } | |
| 5565 } | |
| 5566 | |
| 5567 // Reset all the thread-local PLAB recording arrays | |
| 5568 void CMSCollector::reset_survivor_plab_arrays() { | |
| 5569 for (uint i = 0; i < ParallelGCThreads; i++) { | |
| 5570 _survivor_plab_array[i].reset(); | |
| 5571 } | |
| 5572 } | |
| 5573 | |
| 5574 // Merge the per-thread plab arrays into the global survivor chunk | |
| 5575 // array which will provide the partitioning of the survivor space | |
| 5576 // for CMS rescan. | |
|
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5577 void CMSCollector::merge_survivor_plab_arrays(ContiguousSpace* surv, |
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5578 int no_of_gc_threads) { |
| 0 | 5579 assert(_survivor_plab_array != NULL, "Error"); |
| 5580 assert(_survivor_chunk_array != NULL, "Error"); | |
| 5581 assert(_collectorState == FinalMarking, "Error"); | |
|
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5582 for (int j = 0; j < no_of_gc_threads; j++) { |
| 0 | 5583 _cursor[j] = 0; |
| 5584 } | |
| 5585 HeapWord* top = surv->top(); | |
| 5586 size_t i; | |
| 5587 for (i = 0; i < _survivor_chunk_capacity; i++) { // all sca entries | |
| 5588 HeapWord* min_val = top; // Higher than any PLAB address | |
| 5589 uint min_tid = 0; // position of min_val this round | |
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5590 for (int j = 0; j < no_of_gc_threads; j++) { |
| 0 | 5591 ChunkArray* cur_sca = &_survivor_plab_array[j]; |
| 5592 if (_cursor[j] == cur_sca->end()) { | |
| 5593 continue; | |
| 5594 } | |
| 5595 assert(_cursor[j] < cur_sca->end(), "ctl pt invariant"); | |
| 5596 HeapWord* cur_val = cur_sca->nth(_cursor[j]); | |
| 5597 assert(surv->used_region().contains(cur_val), "Out of bounds value"); | |
| 5598 if (cur_val < min_val) { | |
| 5599 min_tid = j; | |
| 5600 min_val = cur_val; | |
| 5601 } else { | |
| 5602 assert(cur_val < top, "All recorded addresses should be less"); | |
| 5603 } | |
| 5604 } | |
| 5605 // At this point min_val and min_tid are respectively | |
| 5606 // the least address in _survivor_plab_array[j]->nth(_cursor[j]) | |
| 5607 // and the thread (j) that witnesses that address. | |
| 5608 // We record this address in the _survivor_chunk_array[i] | |
| 5609 // and increment _cursor[min_tid] prior to the next round i. | |
| 5610 if (min_val == top) { | |
| 5611 break; | |
| 5612 } | |
| 5613 _survivor_chunk_array[i] = min_val; | |
| 5614 _cursor[min_tid]++; | |
| 5615 } | |
| 5616 // We are all done; record the size of the _survivor_chunk_array | |
| 5617 _survivor_chunk_index = i; // exclusive: [0, i) | |
| 5618 if (PrintCMSStatistics > 0) { | |
| 5619 gclog_or_tty->print(" (Survivor:" SIZE_FORMAT "chunks) ", i); | |
| 5620 } | |
| 5621 // Verify that we used up all the recorded entries | |
| 5622 #ifdef ASSERT | |
| 5623 size_t total = 0; | |
|
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|
5624 for (int j = 0; j < no_of_gc_threads; j++) { |
| 0 | 5625 assert(_cursor[j] == _survivor_plab_array[j].end(), "Ctl pt invariant"); |
| 5626 total += _cursor[j]; | |
| 5627 } | |
| 5628 assert(total == _survivor_chunk_index, "Ctl Pt Invariant"); | |
| 5629 // Check that the merged array is in sorted order | |
| 5630 if (total > 0) { | |
| 5631 for (size_t i = 0; i < total - 1; i++) { | |
| 5632 if (PrintCMSStatistics > 0) { | |
| 5633 gclog_or_tty->print(" (chunk" SIZE_FORMAT ":" INTPTR_FORMAT ") ", | |
| 5634 i, _survivor_chunk_array[i]); | |
| 5635 } | |
| 5636 assert(_survivor_chunk_array[i] < _survivor_chunk_array[i+1], | |
| 5637 "Not sorted"); | |
| 5638 } | |
| 5639 } | |
| 5640 #endif // ASSERT | |
| 5641 } | |
| 5642 | |
| 5643 // Set up the space's par_seq_tasks structure for work claiming | |
| 5644 // for parallel rescan of young gen. | |
| 5645 // See ParRescanTask where this is currently used. | |
| 5646 void | |
| 5647 CMSCollector:: | |
| 5648 initialize_sequential_subtasks_for_young_gen_rescan(int n_threads) { | |
| 5649 assert(n_threads > 0, "Unexpected n_threads argument"); | |
| 5650 DefNewGeneration* dng = (DefNewGeneration*)_young_gen; | |
| 5651 | |
| 5652 // Eden space | |
| 5653 { | |
| 5654 SequentialSubTasksDone* pst = dng->eden()->par_seq_tasks(); | |
| 5655 assert(!pst->valid(), "Clobbering existing data?"); | |
| 5656 // Each valid entry in [0, _eden_chunk_index) represents a task. | |
| 5657 size_t n_tasks = _eden_chunk_index + 1; | |
| 5658 assert(n_tasks == 1 || _eden_chunk_array != NULL, "Error"); | |
|
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|
5659 // Sets the condition for completion of the subtask (how many threads |
|
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|
5660 // need to finish in order to be done). |
|
8b10f48633dc
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|
5661 pst->set_n_threads(n_threads); |
| 0 | 5662 pst->set_n_tasks((int)n_tasks); |
| 5663 } | |
| 5664 | |
| 5665 // Merge the survivor plab arrays into _survivor_chunk_array | |
| 5666 if (_survivor_plab_array != NULL) { | |
|
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|
5667 merge_survivor_plab_arrays(dng->from(), n_threads); |
| 0 | 5668 } else { |
| 5669 assert(_survivor_chunk_index == 0, "Error"); | |
| 5670 } | |
| 5671 | |
| 5672 // To space | |
| 5673 { | |
| 5674 SequentialSubTasksDone* pst = dng->to()->par_seq_tasks(); | |
| 5675 assert(!pst->valid(), "Clobbering existing data?"); | |
|
1833
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|
5676 // Sets the condition for completion of the subtask (how many threads |
|
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|
5677 // need to finish in order to be done). |
|
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|
5678 pst->set_n_threads(n_threads); |
| 0 | 5679 pst->set_n_tasks(1); |
| 5680 assert(pst->valid(), "Error"); | |
| 5681 } | |
| 5682 | |
| 5683 // From space | |
| 5684 { | |
| 5685 SequentialSubTasksDone* pst = dng->from()->par_seq_tasks(); | |
| 5686 assert(!pst->valid(), "Clobbering existing data?"); | |
| 5687 size_t n_tasks = _survivor_chunk_index + 1; | |
| 5688 assert(n_tasks == 1 || _survivor_chunk_array != NULL, "Error"); | |
|
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|
5689 // Sets the condition for completion of the subtask (how many threads |
|
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|
5690 // need to finish in order to be done). |
|
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|
5691 pst->set_n_threads(n_threads); |
| 0 | 5692 pst->set_n_tasks((int)n_tasks); |
| 5693 assert(pst->valid(), "Error"); | |
| 5694 } | |
| 5695 } | |
| 5696 | |
| 5697 // Parallel version of remark | |
| 5698 void CMSCollector::do_remark_parallel() { | |
| 5699 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
|
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|
5700 FlexibleWorkGang* workers = gch->workers(); |
| 0 | 5701 assert(workers != NULL, "Need parallel worker threads."); |
|
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|
5702 // Choose to use the number of GC workers most recently set |
|
bca17e38de00
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|
5703 // into "active_workers". If active_workers is not set, set it |
|
bca17e38de00
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|
5704 // to ParallelGCThreads. |
|
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|
5705 int n_workers = workers->active_workers(); |
|
bca17e38de00
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|
5706 if (n_workers == 0) { |
|
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|
5707 assert(n_workers > 0, "Should have been set during scavenge"); |
|
bca17e38de00
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|
5708 n_workers = ParallelGCThreads; |
|
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|
5709 workers->set_active_workers(n_workers); |
|
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|
5710 } |
| 0 | 5711 CompactibleFreeListSpace* cms_space = _cmsGen->cmsSpace(); |
| 5712 | |
| 5713 CMSParRemarkTask tsk(this, | |
|
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|
5714 cms_space, |
| 0 | 5715 n_workers, workers, task_queues()); |
| 5716 | |
| 5717 // Set up for parallel process_strong_roots work. | |
| 5718 gch->set_par_threads(n_workers); | |
| 5719 // We won't be iterating over the cards in the card table updating | |
| 5720 // the younger_gen cards, so we shouldn't call the following else | |
| 5721 // the verification code as well as subsequent younger_refs_iterate | |
| 5722 // code would get confused. XXX | |
| 5723 // gch->rem_set()->prepare_for_younger_refs_iterate(true); // parallel | |
| 5724 | |
| 5725 // The young gen rescan work will not be done as part of | |
| 5726 // process_strong_roots (which currently doesn't knw how to | |
| 5727 // parallelize such a scan), but rather will be broken up into | |
| 5728 // a set of parallel tasks (via the sampling that the [abortable] | |
| 5729 // preclean phase did of EdenSpace, plus the [two] tasks of | |
| 5730 // scanning the [two] survivor spaces. Further fine-grain | |
| 5731 // parallelization of the scanning of the survivor spaces | |
| 5732 // themselves, and of precleaning of the younger gen itself | |
| 5733 // is deferred to the future. | |
| 5734 initialize_sequential_subtasks_for_young_gen_rescan(n_workers); | |
| 5735 | |
| 5736 // The dirty card rescan work is broken up into a "sequence" | |
| 5737 // of parallel tasks (per constituent space) that are dynamically | |
| 5738 // claimed by the parallel threads. | |
| 5739 cms_space->initialize_sequential_subtasks_for_rescan(n_workers); | |
| 5740 | |
| 5741 // It turns out that even when we're using 1 thread, doing the work in a | |
| 5742 // separate thread causes wide variance in run times. We can't help this | |
| 5743 // in the multi-threaded case, but we special-case n=1 here to get | |
| 5744 // repeatable measurements of the 1-thread overhead of the parallel code. | |
| 5745 if (n_workers > 1) { | |
|
2369
92da084fefc9
6668573: CMS: reference processing crash if ParallelCMSThreads > ParallelGCThreads
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|
5746 // Make refs discovery MT-safe, if it isn't already: it may not |
|
92da084fefc9
6668573: CMS: reference processing crash if ParallelCMSThreads > ParallelGCThreads
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diff
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|
5747 // necessarily be so, since it's possible that we are doing |
|
92da084fefc9
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diff
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|
5748 // ST marking. |
|
92da084fefc9
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diff
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|
5749 ReferenceProcessorMTDiscoveryMutator mt(ref_processor(), true); |
|
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|
5750 GenCollectedHeap::StrongRootsScope srs(gch); |
| 0 | 5751 workers->run_task(&tsk); |
| 5752 } else { | |
|
4876
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stefank
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diff
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|
5753 ReferenceProcessorMTDiscoveryMutator mt(ref_processor(), false); |
|
989
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|
5754 GenCollectedHeap::StrongRootsScope srs(gch); |
| 0 | 5755 tsk.work(0); |
| 5756 } | |
|
6725
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|
5757 |
| 0 | 5758 gch->set_par_threads(0); // 0 ==> non-parallel. |
| 5759 // restore, single-threaded for now, any preserved marks | |
| 5760 // as a result of work_q overflow | |
| 5761 restore_preserved_marks_if_any(); | |
| 5762 } | |
| 5763 | |
| 5764 // Non-parallel version of remark | |
| 5765 void CMSCollector::do_remark_non_parallel() { | |
| 5766 ResourceMark rm; | |
| 5767 HandleMark hm; | |
| 5768 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
|
4876
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|
5769 ReferenceProcessorMTDiscoveryMutator mt(ref_processor(), false); |
|
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|
5770 |
| 0 | 5771 MarkRefsIntoAndScanClosure |
|
6725
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|
5772 mrias_cl(_span, ref_processor(), &_markBitMap, NULL /* not precleaning */, |
|
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|
5773 &_markStack, this, |
| 0 | 5774 false /* should_yield */, false /* not precleaning */); |
| 5775 MarkFromDirtyCardsClosure | |
| 5776 markFromDirtyCardsClosure(this, _span, | |
| 5777 NULL, // space is set further below | |
|
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|
5778 &_markBitMap, &_markStack, &mrias_cl); |
| 0 | 5779 { |
| 10405 | 5780 GCTraceTime t("grey object rescan", PrintGCDetails, false, _gc_timer_cm); |
|
342
37f87013dfd8
6711316: Open source the Garbage-First garbage collector
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143
diff
changeset
|
5781 // Iterate over the dirty cards, setting the corresponding bits in the |
|
37f87013dfd8
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diff
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|
5782 // mod union table. |
| 0 | 5783 { |
| 5784 ModUnionClosure modUnionClosure(&_modUnionTable); | |
| 5785 _ct->ct_bs()->dirty_card_iterate( | |
| 5786 _cmsGen->used_region(), | |
| 5787 &modUnionClosure); | |
| 5788 } | |
| 5789 // Having transferred these marks into the modUnionTable, we just need | |
| 5790 // to rescan the marked objects on the dirty cards in the modUnionTable. | |
| 5791 // The initial marking may have been done during an asynchronous | |
| 5792 // collection so there may be dirty bits in the mod-union table. | |
| 5793 const int alignment = | |
| 5794 CardTableModRefBS::card_size * BitsPerWord; | |
| 5795 { | |
| 5796 // ... First handle dirty cards in CMS gen | |
| 5797 markFromDirtyCardsClosure.set_space(_cmsGen->cmsSpace()); | |
| 5798 MemRegion ur = _cmsGen->used_region(); | |
| 5799 HeapWord* lb = ur.start(); | |
| 5800 HeapWord* ub = (HeapWord*)round_to((intptr_t)ur.end(), alignment); | |
| 5801 MemRegion cms_span(lb, ub); | |
| 5802 _modUnionTable.dirty_range_iterate_clear(cms_span, | |
| 5803 &markFromDirtyCardsClosure); | |
| 5804 verify_work_stacks_empty(); | |
| 5805 if (PrintCMSStatistics != 0) { | |
| 5806 gclog_or_tty->print(" (re-scanned "SIZE_FORMAT" dirty cards in cms gen) ", | |
| 5807 markFromDirtyCardsClosure.num_dirty_cards()); | |
| 5808 } | |
| 5809 } | |
| 5810 } | |
| 5811 if (VerifyDuringGC && | |
| 5812 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
| 5813 HandleMark hm; // Discard invalid handles created during verification | |
|
6865
4202510ee0fe
8000831: Heap verification output incorrect/incomplete
johnc
parents:
6787
diff
changeset
|
5814 Universe::verify(); |
| 0 | 5815 } |
| 5816 { | |
| 10405 | 5817 GCTraceTime t("root rescan", PrintGCDetails, false, _gc_timer_cm); |
| 0 | 5818 |
| 5819 verify_work_stacks_empty(); | |
| 5820 | |
| 5821 gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel. | |
|
989
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798
diff
changeset
|
5822 GenCollectedHeap::StrongRootsScope srs(gch); |
| 0 | 5823 gch->gen_process_strong_roots(_cmsGen->level(), |
| 5824 true, // younger gens as roots | |
|
989
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diff
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|
5825 false, // use the local StrongRootsScope |
|
6725
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|
5826 false, // not scavenging |
| 0 | 5827 SharedHeap::ScanningOption(roots_scanning_options()), |
|
989
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6863023: need non-perm oops in code cache for JSR 292
jrose
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798
diff
changeset
|
5828 &mrias_cl, |
|
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
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798
diff
changeset
|
5829 true, // walk code active on stacks |
|
6725
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|
5830 NULL, |
|
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|
5831 NULL); // The dirty klasses will be handled below |
|
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|
5832 |
|
989
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6863023: need non-perm oops in code cache for JSR 292
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diff
changeset
|
5833 assert(should_unload_classes() |
|
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jrose
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798
diff
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|
5834 || (roots_scanning_options() & SharedHeap::SO_CodeCache), |
|
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jrose
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798
diff
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|
5835 "if we didn't scan the code cache, we have to be ready to drop nmethods with expired weak oops"); |
| 0 | 5836 } |
|
6725
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|
5837 |
|
da91efe96a93
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|
5838 { |
| 10405 | 5839 GCTraceTime t("visit unhandled CLDs", PrintGCDetails, false, _gc_timer_cm); |
|
6725
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|
5840 |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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|
5841 verify_work_stacks_empty(); |
|
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diff
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|
5842 |
|
da91efe96a93
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|
5843 // Scan all class loader data objects that might have been introduced |
|
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diff
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|
5844 // during concurrent marking. |
|
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diff
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|
5845 ResourceMark rm; |
|
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|
5846 GrowableArray<ClassLoaderData*>* array = ClassLoaderDataGraph::new_clds(); |
|
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|
5847 for (int i = 0; i < array->length(); i++) { |
|
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diff
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|
5848 mrias_cl.do_class_loader_data(array->at(i)); |
|
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|
5849 } |
|
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|
5850 |
|
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6964458: Reimplement class meta-data storage to use native memory
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diff
changeset
|
5851 // We don't need to keep track of new CLDs anymore. |
|
da91efe96a93
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|
5852 ClassLoaderDataGraph::remember_new_clds(false); |
|
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|
5853 |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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|
5854 verify_work_stacks_empty(); |
|
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diff
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|
5855 } |
|
da91efe96a93
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|
5856 |
|
da91efe96a93
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|
5857 { |
| 10405 | 5858 GCTraceTime t("dirty klass scan", PrintGCDetails, false, _gc_timer_cm); |
|
6725
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|
5859 |
|
da91efe96a93
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changeset
|
5860 verify_work_stacks_empty(); |
|
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|
5861 |
|
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|
5862 RemarkKlassClosure remark_klass_closure(&mrias_cl); |
|
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|
5863 ClassLoaderDataGraph::classes_do(&remark_klass_closure); |
|
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|
5864 |
|
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|
5865 verify_work_stacks_empty(); |
|
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|
5866 } |
|
da91efe96a93
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|
5867 |
|
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|
5868 // We might have added oops to ClassLoaderData::_handles during the |
|
da91efe96a93
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|
5869 // concurrent marking phase. These oops point to newly allocated objects |
|
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|
5870 // that are guaranteed to be kept alive. Either by the direct allocation |
|
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|
5871 // code, or when the young collector processes the strong roots. Hence, |
|
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|
5872 // we don't have to revisit the _handles block during the remark phase. |
|
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|
5873 |
| 0 | 5874 verify_work_stacks_empty(); |
| 5875 // Restore evacuated mark words, if any, used for overflow list links | |
| 5876 if (!CMSOverflowEarlyRestoration) { | |
| 5877 restore_preserved_marks_if_any(); | |
| 5878 } | |
| 5879 verify_overflow_empty(); | |
| 5880 } | |
| 5881 | |
| 5882 //////////////////////////////////////////////////////// | |
| 5883 // Parallel Reference Processing Task Proxy Class | |
| 5884 //////////////////////////////////////////////////////// | |
|
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|
5885 class CMSRefProcTaskProxy: public AbstractGangTaskWOopQueues { |
| 0 | 5886 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; |
| 5887 CMSCollector* _collector; | |
| 5888 CMSBitMap* _mark_bit_map; | |
|
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|
5889 const MemRegion _span; |
| 0 | 5890 ProcessTask& _task; |
| 5891 | |
| 5892 public: | |
| 5893 CMSRefProcTaskProxy(ProcessTask& task, | |
| 5894 CMSCollector* collector, | |
| 5895 const MemRegion& span, | |
| 5896 CMSBitMap* mark_bit_map, | |
|
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|
5897 AbstractWorkGang* workers, |
| 0 | 5898 OopTaskQueueSet* task_queues): |
|
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|
5899 // XXX Should superclass AGTWOQ also know about AWG since it knows |
|
92da084fefc9
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|
5900 // about the task_queues used by the AWG? Then it could initialize |
|
92da084fefc9
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|
5901 // the terminator() object. See 6984287. The set_for_termination() |
|
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|
5902 // below is a temporary band-aid for the regression in 6984287. |
|
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|
5903 AbstractGangTaskWOopQueues("Process referents by policy in parallel", |
|
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|
5904 task_queues), |
| 0 | 5905 _task(task), |
|
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|
5906 _collector(collector), _span(span), _mark_bit_map(mark_bit_map) |
|
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|
5907 { |
|
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|
5908 assert(_collector->_span.equals(_span) && !_span.is_empty(), |
|
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|
5909 "Inconsistency in _span"); |
|
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|
5910 set_for_termination(workers->active_workers()); |
|
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|
5911 } |
| 0 | 5912 |
|
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|
5913 OopTaskQueueSet* task_queues() { return queues(); } |
| 0 | 5914 |
| 5915 OopTaskQueue* work_queue(int i) { return task_queues()->queue(i); } | |
| 5916 | |
| 5917 void do_work_steal(int i, | |
| 5918 CMSParDrainMarkingStackClosure* drain, | |
| 5919 CMSParKeepAliveClosure* keep_alive, | |
| 5920 int* seed); | |
| 5921 | |
|
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|
5922 virtual void work(uint worker_id); |
| 0 | 5923 }; |
| 5924 | |
|
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|
5925 void CMSRefProcTaskProxy::work(uint worker_id) { |
|
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|
5926 assert(_collector->_span.equals(_span), "Inconsistency in _span"); |
| 0 | 5927 CMSParKeepAliveClosure par_keep_alive(_collector, _span, |
| 935 | 5928 _mark_bit_map, |
|
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changeset
|
5929 work_queue(worker_id)); |
| 0 | 5930 CMSParDrainMarkingStackClosure par_drain_stack(_collector, _span, |
| 935 | 5931 _mark_bit_map, |
|
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diff
changeset
|
5932 work_queue(worker_id)); |
|
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|
5933 CMSIsAliveClosure is_alive_closure(_span, _mark_bit_map); |
|
4728
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|
5934 _task.work(worker_id, is_alive_closure, par_keep_alive, par_drain_stack); |
| 0 | 5935 if (_task.marks_oops_alive()) { |
|
4728
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diff
changeset
|
5936 do_work_steal(worker_id, &par_drain_stack, &par_keep_alive, |
|
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changeset
|
5937 _collector->hash_seed(worker_id)); |
|
441e946dc1af
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diff
changeset
|
5938 } |
|
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diff
changeset
|
5939 assert(work_queue(worker_id)->size() == 0, "work_queue should be empty"); |
| 0 | 5940 assert(_collector->_overflow_list == NULL, "non-empty _overflow_list"); |
| 5941 } | |
| 5942 | |
| 5943 class CMSRefEnqueueTaskProxy: public AbstractGangTask { | |
| 5944 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; | |
| 5945 EnqueueTask& _task; | |
| 5946 | |
| 5947 public: | |
| 5948 CMSRefEnqueueTaskProxy(EnqueueTask& task) | |
| 5949 : AbstractGangTask("Enqueue reference objects in parallel"), | |
| 5950 _task(task) | |
| 5951 { } | |
| 5952 | |
|
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changeset
|
5953 virtual void work(uint worker_id) |
| 0 | 5954 { |
|
4728
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diff
changeset
|
5955 _task.work(worker_id); |
| 0 | 5956 } |
| 5957 }; | |
| 5958 | |
| 5959 CMSParKeepAliveClosure::CMSParKeepAliveClosure(CMSCollector* collector, | |
|
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|
5960 MemRegion span, CMSBitMap* bit_map, OopTaskQueue* work_queue): |
| 0 | 5961 _span(span), |
| 5962 _bit_map(bit_map), | |
| 5963 _work_queue(work_queue), | |
|
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coleenp
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diff
changeset
|
5964 _mark_and_push(collector, span, bit_map, work_queue), |
| 0 | 5965 _low_water_mark(MIN2((uint)(work_queue->max_elems()/4), |
| 5966 (uint)(CMSWorkQueueDrainThreshold * ParallelGCThreads))) | |
| 5967 { } | |
| 5968 | |
| 5969 // . see if we can share work_queues with ParNew? XXX | |
| 5970 void CMSRefProcTaskProxy::do_work_steal(int i, | |
| 5971 CMSParDrainMarkingStackClosure* drain, | |
| 5972 CMSParKeepAliveClosure* keep_alive, | |
| 5973 int* seed) { | |
| 5974 OopTaskQueue* work_q = work_queue(i); | |
| 5975 NOT_PRODUCT(int num_steals = 0;) | |
| 5976 oop obj_to_scan; | |
| 5977 | |
| 5978 while (true) { | |
| 5979 // Completely finish any left over work from (an) earlier round(s) | |
| 5980 drain->trim_queue(0); | |
|
679
cea947c8a988
6819891: ParNew: Fix work queue overflow code to deal correctly with +UseCompressedOops
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628
diff
changeset
|
5981 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
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628
diff
changeset
|
5982 (size_t)ParGCDesiredObjsFromOverflowList); |
| 0 | 5983 // Now check if there's any work in the overflow list |
|
1833
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changeset
|
5984 // Passing ParallelGCThreads as the third parameter, no_of_gc_threads, |
|
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diff
changeset
|
5985 // only affects the number of attempts made to get work from the |
|
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diff
changeset
|
5986 // overflow list and does not affect the number of workers. Just |
|
8b10f48633dc
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jmasa
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diff
changeset
|
5987 // pass ParallelGCThreads so this behavior is unchanged. |
| 0 | 5988 if (_collector->par_take_from_overflow_list(num_from_overflow_list, |
|
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8b10f48633dc
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jmasa
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diff
changeset
|
5989 work_q, |
|
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1777
diff
changeset
|
5990 ParallelGCThreads)) { |
| 0 | 5991 // Found something in global overflow list; |
| 5992 // not yet ready to go stealing work from others. | |
| 5993 // We'd like to assert(work_q->size() != 0, ...) | |
| 5994 // because we just took work from the overflow list, | |
| 5995 // but of course we can't, since all of that might have | |
| 5996 // been already stolen from us. | |
| 5997 continue; | |
| 5998 } | |
| 5999 // Verify that we have no work before we resort to stealing | |
| 6000 assert(work_q->size() == 0, "Have work, shouldn't steal"); | |
| 6001 // Try to steal from other queues that have work | |
| 6002 if (task_queues()->steal(i, seed, /* reference */ obj_to_scan)) { | |
| 6003 NOT_PRODUCT(num_steals++;) | |
| 6004 assert(obj_to_scan->is_oop(), "Oops, not an oop!"); | |
| 6005 assert(_mark_bit_map->isMarked((HeapWord*)obj_to_scan), "Stole an unmarked oop?"); | |
| 6006 // Do scanning work | |
| 6007 obj_to_scan->oop_iterate(keep_alive); | |
| 6008 // Loop around, finish this work, and try to steal some more | |
| 6009 } else if (terminator()->offer_termination()) { | |
| 6010 break; // nirvana from the infinite cycle | |
| 6011 } | |
| 6012 } | |
| 6013 NOT_PRODUCT( | |
| 6014 if (PrintCMSStatistics != 0) { | |
| 6015 gclog_or_tty->print("\n\t(%d: stole %d oops)", i, num_steals); | |
| 6016 } | |
| 6017 ) | |
| 6018 } | |
| 6019 | |
| 6020 void CMSRefProcTaskExecutor::execute(ProcessTask& task) | |
| 6021 { | |
| 6022 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
|
1833
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diff
changeset
|
6023 FlexibleWorkGang* workers = gch->workers(); |
| 0 | 6024 assert(workers != NULL, "Need parallel worker threads."); |
| 6025 CMSRefProcTaskProxy rp_task(task, &_collector, | |
| 6026 _collector.ref_processor()->span(), | |
| 6027 _collector.markBitMap(), | |
|
1833
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jmasa
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diff
changeset
|
6028 workers, _collector.task_queues()); |
| 0 | 6029 workers->run_task(&rp_task); |
| 6030 } | |
| 6031 | |
| 6032 void CMSRefProcTaskExecutor::execute(EnqueueTask& task) | |
| 6033 { | |
| 6034 | |
| 6035 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
|
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jmasa
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diff
changeset
|
6036 FlexibleWorkGang* workers = gch->workers(); |
| 0 | 6037 assert(workers != NULL, "Need parallel worker threads."); |
| 6038 CMSRefEnqueueTaskProxy enq_task(task); | |
| 6039 workers->run_task(&enq_task); | |
| 6040 } | |
| 6041 | |
| 6042 void CMSCollector::refProcessingWork(bool asynch, bool clear_all_soft_refs) { | |
| 6043 | |
| 6044 ResourceMark rm; | |
| 6045 HandleMark hm; | |
| 6046 | |
| 6047 ReferenceProcessor* rp = ref_processor(); | |
| 6048 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
|
6049 assert(!rp->enqueuing_is_done(), "Enqueuing should not be complete"); |
|
c96030fff130
6684579: SoftReference processing can be made more efficient
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452
diff
changeset
|
6050 // Process weak references. |
|
457
27a80744a83b
6778647: snap(), snap_policy() should be renamed setup(), setup_policy()
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453
diff
changeset
|
6051 rp->setup_policy(clear_all_soft_refs); |
|
453
c96030fff130
6684579: SoftReference processing can be made more efficient
ysr
parents:
452
diff
changeset
|
6052 verify_work_stacks_empty(); |
|
c96030fff130
6684579: SoftReference processing can be made more efficient
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452
diff
changeset
|
6053 |
| 0 | 6054 CMSKeepAliveClosure cmsKeepAliveClosure(this, _span, &_markBitMap, |
|
6725
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diff
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|
6055 &_markStack, false /* !preclean */); |
| 0 | 6056 CMSDrainMarkingStackClosure cmsDrainMarkingStackClosure(this, |
| 6057 _span, &_markBitMap, &_markStack, | |
|
452
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
6058 &cmsKeepAliveClosure, false /* !preclean */); |
| 0 | 6059 { |
| 10405 | 6060 GCTraceTime t("weak refs processing", PrintGCDetails, false, _gc_timer_cm); |
| 6061 | |
| 6062 ReferenceProcessorStats stats; | |
| 0 | 6063 if (rp->processing_is_mt()) { |
|
1833
8b10f48633dc
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diff
changeset
|
6064 // Set the degree of MT here. If the discovery is done MT, there |
|
8b10f48633dc
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jmasa
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1777
diff
changeset
|
6065 // may have been a different number of threads doing the discovery |
|
8b10f48633dc
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jmasa
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diff
changeset
|
6066 // and a different number of discovered lists may have Ref objects. |
|
8b10f48633dc
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jmasa
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diff
changeset
|
6067 // That is OK as long as the Reference lists are balanced (see |
|
8b10f48633dc
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diff
changeset
|
6068 // balance_all_queues() and balance_queues()). |
|
4095
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
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3979
diff
changeset
|
6069 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
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3979
diff
changeset
|
6070 int active_workers = ParallelGCThreads; |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
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3979
diff
changeset
|
6071 FlexibleWorkGang* workers = gch->workers(); |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
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diff
changeset
|
6072 if (workers != NULL) { |
|
bca17e38de00
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3979
diff
changeset
|
6073 active_workers = workers->active_workers(); |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
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3979
diff
changeset
|
6074 // The expectation is that active_workers will have already |
|
bca17e38de00
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jmasa
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3979
diff
changeset
|
6075 // 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
|
6076 // investigate. |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
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3979
diff
changeset
|
6077 assert(active_workers > 0, "Should have been set during scavenge"); |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
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3979
diff
changeset
|
6078 } |
|
bca17e38de00
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3979
diff
changeset
|
6079 rp->set_active_mt_degree(active_workers); |
| 0 | 6080 CMSRefProcTaskExecutor task_executor(*this); |
| 10405 | 6081 stats = rp->process_discovered_references(&_is_alive_closure, |
| 0 | 6082 &cmsKeepAliveClosure, |
| 6083 &cmsDrainMarkingStackClosure, | |
| 10405 | 6084 &task_executor, |
| 6085 _gc_timer_cm); | |
| 0 | 6086 } else { |
| 10405 | 6087 stats = rp->process_discovered_references(&_is_alive_closure, |
| 0 | 6088 &cmsKeepAliveClosure, |
| 6089 &cmsDrainMarkingStackClosure, | |
| 10405 | 6090 NULL, |
| 6091 _gc_timer_cm); | |
| 6092 } | |
| 6093 _gc_tracer_cm->report_gc_reference_stats(stats); | |
| 6094 | |
|
10188
2f50bc369470
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stefank
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10186
diff
changeset
|
6095 } |
|
2f50bc369470
8013160: NPG: Remove unnecessary mark stack draining after CodeCache::do_unloading
stefank
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10186
diff
changeset
|
6096 |
|
2f50bc369470
8013160: NPG: Remove unnecessary mark stack draining after CodeCache::do_unloading
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parents:
10186
diff
changeset
|
6097 // This is the point where the entire marking should have completed. |
|
2f50bc369470
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parents:
10186
diff
changeset
|
6098 verify_work_stacks_empty(); |
| 0 | 6099 |
|
94
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
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9
diff
changeset
|
6100 if (should_unload_classes()) { |
| 0 | 6101 { |
| 10405 | 6102 GCTraceTime t("class unloading", PrintGCDetails, false, _gc_timer_cm); |
| 0 | 6103 |
|
10188
2f50bc369470
8013160: NPG: Remove unnecessary mark stack draining after CodeCache::do_unloading
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10186
diff
changeset
|
6104 // Unload classes and purge the SystemDictionary. |
| 0 | 6105 bool purged_class = SystemDictionary::do_unloading(&_is_alive_closure); |
| 6106 | |
|
10188
2f50bc369470
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stefank
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10186
diff
changeset
|
6107 // Unload nmethods. |
|
6787
8966c2d65d96
7200470: KeepAliveClosure not needed in CodeCache::do_unloading
brutisso
parents:
6755
diff
changeset
|
6108 CodeCache::do_unloading(&_is_alive_closure, purged_class); |
| 0 | 6109 |
|
10188
2f50bc369470
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10186
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changeset
|
6110 // Prune dead klasses from subklass/sibling/implementor lists. |
|
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6111 Klass::clean_weak_klass_links(&_is_alive_closure); |
| 0 | 6112 } |
| 6113 | |
| 6114 { | |
| 10405 | 6115 GCTraceTime t("scrub symbol table", PrintGCDetails, false, _gc_timer_cm); |
|
2177
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|
6116 // Clean up unreferenced symbols in symbol table. |
|
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|
6117 SymbolTable::unlink(); |
| 0 | 6118 } |
| 6119 } | |
| 6120 | |
|
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6121 // CMS doesn't use the StringTable as hard roots when class unloading is turned off. |
|
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6122 // Need to check if we really scanned the StringTable. |
|
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6123 if ((roots_scanning_options() & SharedHeap::SO_Strings) == 0) { |
| 10405 | 6124 GCTraceTime t("scrub string table", PrintGCDetails, false, _gc_timer_cm); |
|
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6125 // Delete entries for dead interned strings. |
|
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|
6126 StringTable::unlink(&_is_alive_closure); |
|
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|
6127 } |
|
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6128 |
| 0 | 6129 // Restore any preserved marks as a result of mark stack or |
| 6130 // work queue overflow | |
| 6131 restore_preserved_marks_if_any(); // done single-threaded for now | |
| 6132 | |
| 6133 rp->set_enqueuing_is_done(true); | |
| 6134 if (rp->processing_is_mt()) { | |
|
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|
6135 rp->balance_all_queues(); |
| 0 | 6136 CMSRefProcTaskExecutor task_executor(*this); |
| 6137 rp->enqueue_discovered_references(&task_executor); | |
| 6138 } else { | |
| 6139 rp->enqueue_discovered_references(NULL); | |
| 6140 } | |
| 6141 rp->verify_no_references_recorded(); | |
| 6142 assert(!rp->discovery_enabled(), "should have been disabled"); | |
| 6143 } | |
| 6144 | |
| 6145 #ifndef PRODUCT | |
| 6146 void CMSCollector::check_correct_thread_executing() { | |
| 6147 Thread* t = Thread::current(); | |
| 6148 // Only the VM thread or the CMS thread should be here. | |
| 6149 assert(t->is_ConcurrentGC_thread() || t->is_VM_thread(), | |
| 6150 "Unexpected thread type"); | |
| 6151 // If this is the vm thread, the foreground process | |
| 6152 // should not be waiting. Note that _foregroundGCIsActive is | |
| 6153 // true while the foreground collector is waiting. | |
| 6154 if (_foregroundGCShouldWait) { | |
| 6155 // We cannot be the VM thread | |
| 6156 assert(t->is_ConcurrentGC_thread(), | |
| 6157 "Should be CMS thread"); | |
| 6158 } else { | |
| 6159 // We can be the CMS thread only if we are in a stop-world | |
| 6160 // phase of CMS collection. | |
| 6161 if (t->is_ConcurrentGC_thread()) { | |
| 6162 assert(_collectorState == InitialMarking || | |
| 6163 _collectorState == FinalMarking, | |
| 6164 "Should be a stop-world phase"); | |
| 6165 // The CMS thread should be holding the CMS_token. | |
| 6166 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 6167 "Potential interference with concurrently " | |
| 6168 "executing VM thread"); | |
| 6169 } | |
| 6170 } | |
| 6171 } | |
| 6172 #endif | |
| 6173 | |
| 6174 void CMSCollector::sweep(bool asynch) { | |
| 6175 assert(_collectorState == Sweeping, "just checking"); | |
| 6176 check_correct_thread_executing(); | |
| 6177 verify_work_stacks_empty(); | |
| 6178 verify_overflow_empty(); | |
|
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6179 increment_sweep_count(); |
|
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6180 TraceCMSMemoryManagerStats tms(_collectorState,GenCollectedHeap::heap()->gc_cause()); |
|
1703
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6181 |
|
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6182 _inter_sweep_timer.stop(); |
|
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6183 _inter_sweep_estimate.sample(_inter_sweep_timer.seconds()); |
| 0 | 6184 size_policy()->avg_cms_free_at_sweep()->sample(_cmsGen->free()); |
| 6185 | |
|
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6186 assert(!_intra_sweep_timer.is_active(), "Should not be active"); |
|
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6187 _intra_sweep_timer.reset(); |
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6188 _intra_sweep_timer.start(); |
| 0 | 6189 if (asynch) { |
| 6190 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
| 6191 CMSPhaseAccounting pa(this, "sweep", !PrintGCDetails); | |
|
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6192 // First sweep the old gen |
| 0 | 6193 { |
| 6194 CMSTokenSyncWithLocks ts(true, _cmsGen->freelistLock(), | |
| 6195 bitMapLock()); | |
| 6196 sweepWork(_cmsGen, asynch); | |
| 6197 } | |
| 6198 | |
| 6199 // Update Universe::_heap_*_at_gc figures. | |
| 6200 // We need all the free list locks to make the abstract state | |
| 6201 // transition from Sweeping to Resetting. See detailed note | |
| 6202 // further below. | |
| 6203 { | |
|
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|
6204 CMSTokenSyncWithLocks ts(true, _cmsGen->freelistLock()); |
| 0 | 6205 // Update heap occupancy information which is used as |
| 6206 // input to soft ref clearing policy at the next gc. | |
| 6207 Universe::update_heap_info_at_gc(); | |
| 6208 _collectorState = Resizing; | |
| 6209 } | |
| 6210 } else { | |
| 6211 // already have needed locks | |
| 6212 sweepWork(_cmsGen, asynch); | |
| 6213 // Update heap occupancy information which is used as | |
| 6214 // input to soft ref clearing policy at the next gc. | |
| 6215 Universe::update_heap_info_at_gc(); | |
| 6216 _collectorState = Resizing; | |
| 6217 } | |
| 6218 verify_work_stacks_empty(); | |
| 6219 verify_overflow_empty(); | |
| 6220 | |
|
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|
6221 if (should_unload_classes()) { |
|
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|
6222 ClassLoaderDataGraph::purge(); |
|
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|
6223 } |
|
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|
6224 |
|
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|
6225 _intra_sweep_timer.stop(); |
|
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|
6226 _intra_sweep_estimate.sample(_intra_sweep_timer.seconds()); |
|
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6227 |
|
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|
6228 _inter_sweep_timer.reset(); |
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|
6229 _inter_sweep_timer.start(); |
| 0 | 6230 |
| 4911 | 6231 // We need to use a monotonically non-deccreasing time in ms |
| 6232 // or we will see time-warp warnings and os::javaTimeMillis() | |
| 6233 // does not guarantee monotonicity. | |
| 6234 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; | |
| 6235 update_time_of_last_gc(now); | |
| 0 | 6236 |
| 6237 // NOTE on abstract state transitions: | |
| 6238 // Mutators allocate-live and/or mark the mod-union table dirty | |
| 6239 // based on the state of the collection. The former is done in | |
| 6240 // the interval [Marking, Sweeping] and the latter in the interval | |
| 6241 // [Marking, Sweeping). Thus the transitions into the Marking state | |
| 6242 // and out of the Sweeping state must be synchronously visible | |
| 6243 // globally to the mutators. | |
| 6244 // The transition into the Marking state happens with the world | |
| 6245 // stopped so the mutators will globally see it. Sweeping is | |
| 6246 // done asynchronously by the background collector so the transition | |
| 6247 // from the Sweeping state to the Resizing state must be done | |
| 6248 // under the freelistLock (as is the check for whether to | |
| 6249 // allocate-live and whether to dirty the mod-union table). | |
| 6250 assert(_collectorState == Resizing, "Change of collector state to" | |
| 6251 " Resizing must be done under the freelistLocks (plural)"); | |
| 6252 | |
|
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|
6253 // Now that sweeping has been completed, we clear |
|
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|
6254 // the incremental_collection_failed flag, |
| 0 | 6255 // thus inviting a younger gen collection to promote into |
| 6256 // this generation. If such a promotion may still fail, | |
| 6257 // the flag will be set again when a young collection is | |
| 6258 // attempted. | |
| 6259 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
|
1888
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|
6260 gch->clear_incremental_collection_failed(); // Worth retrying as fresh space may have been freed up |
| 0 | 6261 gch->update_full_collections_completed(_collection_count_start); |
| 6262 } | |
| 6263 | |
| 6264 // FIX ME!!! Looks like this belongs in CFLSpace, with | |
| 6265 // CMSGen merely delegating to it. | |
| 6266 void ConcurrentMarkSweepGeneration::setNearLargestChunk() { | |
|
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|
6267 double nearLargestPercent = FLSLargestBlockCoalesceProximity; |
| 0 | 6268 HeapWord* minAddr = _cmsSpace->bottom(); |
| 6269 HeapWord* largestAddr = | |
|
6028
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7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
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diff
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|
6270 (HeapWord*) _cmsSpace->dictionary()->find_largest_dict(); |
|
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|
6271 if (largestAddr == NULL) { |
| 0 | 6272 // The dictionary appears to be empty. In this case |
| 6273 // try to coalesce at the end of the heap. | |
| 6274 largestAddr = _cmsSpace->end(); | |
| 6275 } | |
| 6276 size_t largestOffset = pointer_delta(largestAddr, minAddr); | |
| 6277 size_t nearLargestOffset = | |
| 6278 (size_t)((double)largestOffset * nearLargestPercent) - MinChunkSize; | |
|
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|
6279 if (PrintFLSStatistics != 0) { |
|
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|
6280 gclog_or_tty->print_cr( |
|
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|
6281 "CMS: Large Block: " PTR_FORMAT ";" |
|
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|
6282 " Proximity: " PTR_FORMAT " -> " PTR_FORMAT, |
|
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|
6283 largestAddr, |
|
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|
6284 _cmsSpace->nearLargestChunk(), minAddr + nearLargestOffset); |
|
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|
6285 } |
| 0 | 6286 _cmsSpace->set_nearLargestChunk(minAddr + nearLargestOffset); |
| 6287 } | |
| 6288 | |
| 6289 bool ConcurrentMarkSweepGeneration::isNearLargestChunk(HeapWord* addr) { | |
| 6290 return addr >= _cmsSpace->nearLargestChunk(); | |
| 6291 } | |
| 6292 | |
| 6293 FreeChunk* ConcurrentMarkSweepGeneration::find_chunk_at_end() { | |
| 6294 return _cmsSpace->find_chunk_at_end(); | |
| 6295 } | |
| 6296 | |
| 6297 void ConcurrentMarkSweepGeneration::update_gc_stats(int current_level, | |
| 6298 bool full) { | |
| 6299 // The next lower level has been collected. Gather any statistics | |
| 6300 // that are of interest at this point. | |
| 6301 if (!full && (current_level + 1) == level()) { | |
| 6302 // Gather statistics on the young generation collection. | |
| 6303 collector()->stats().record_gc0_end(used()); | |
| 6304 } | |
| 6305 } | |
| 6306 | |
| 6307 CMSAdaptiveSizePolicy* ConcurrentMarkSweepGeneration::size_policy() { | |
| 6308 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 6309 assert(gch->kind() == CollectedHeap::GenCollectedHeap, | |
| 6310 "Wrong type of heap"); | |
| 6311 CMSAdaptiveSizePolicy* sp = (CMSAdaptiveSizePolicy*) | |
| 6312 gch->gen_policy()->size_policy(); | |
| 6313 assert(sp->is_gc_cms_adaptive_size_policy(), | |
| 6314 "Wrong type of size policy"); | |
| 6315 return sp; | |
| 6316 } | |
| 6317 | |
| 6318 void ConcurrentMarkSweepGeneration::rotate_debug_collection_type() { | |
| 6319 if (PrintGCDetails && Verbose) { | |
| 6320 gclog_or_tty->print("Rotate from %d ", _debug_collection_type); | |
| 6321 } | |
| 6322 _debug_collection_type = (CollectionTypes) (_debug_collection_type + 1); | |
| 6323 _debug_collection_type = | |
| 6324 (CollectionTypes) (_debug_collection_type % Unknown_collection_type); | |
| 6325 if (PrintGCDetails && Verbose) { | |
| 6326 gclog_or_tty->print_cr("to %d ", _debug_collection_type); | |
| 6327 } | |
| 6328 } | |
| 6329 | |
| 6330 void CMSCollector::sweepWork(ConcurrentMarkSweepGeneration* gen, | |
| 6331 bool asynch) { | |
| 6332 // We iterate over the space(s) underlying this generation, | |
| 6333 // checking the mark bit map to see if the bits corresponding | |
| 6334 // to specific blocks are marked or not. Blocks that are | |
| 6335 // marked are live and are not swept up. All remaining blocks | |
| 6336 // are swept up, with coalescing on-the-fly as we sweep up | |
| 6337 // contiguous free and/or garbage blocks: | |
| 6338 // We need to ensure that the sweeper synchronizes with allocators | |
| 6339 // and stop-the-world collectors. In particular, the following | |
| 6340 // locks are used: | |
| 6341 // . CMS token: if this is held, a stop the world collection cannot occur | |
| 6342 // . freelistLock: if this is held no allocation can occur from this | |
| 6343 // generation by another thread | |
| 6344 // . bitMapLock: if this is held, no other thread can access or update | |
| 6345 // | |
| 6346 | |
| 6347 // Note that we need to hold the freelistLock if we use | |
| 6348 // block iterate below; else the iterator might go awry if | |
| 6349 // a mutator (or promotion) causes block contents to change | |
| 6350 // (for instance if the allocator divvies up a block). | |
| 6351 // If we hold the free list lock, for all practical purposes | |
| 6352 // young generation GC's can't occur (they'll usually need to | |
| 6353 // promote), so we might as well prevent all young generation | |
| 6354 // GC's while we do a sweeping step. For the same reason, we might | |
| 6355 // as well take the bit map lock for the entire duration | |
| 6356 | |
| 6357 // check that we hold the requisite locks | |
| 6358 assert(have_cms_token(), "Should hold cms token"); | |
| 6359 assert( (asynch && ConcurrentMarkSweepThread::cms_thread_has_cms_token()) | |
| 6360 || (!asynch && ConcurrentMarkSweepThread::vm_thread_has_cms_token()), | |
| 6361 "Should possess CMS token to sweep"); | |
| 6362 assert_lock_strong(gen->freelistLock()); | |
| 6363 assert_lock_strong(bitMapLock()); | |
| 6364 | |
|
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|
6365 assert(!_inter_sweep_timer.is_active(), "Was switched off in an outer context"); |
|
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|
6366 assert(_intra_sweep_timer.is_active(), "Was switched on in an outer context"); |
|
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|
6367 gen->cmsSpace()->beginSweepFLCensus((float)(_inter_sweep_timer.seconds()), |
|
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|
6368 _inter_sweep_estimate.padded_average(), |
|
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|
6369 _intra_sweep_estimate.padded_average()); |
| 0 | 6370 gen->setNearLargestChunk(); |
| 6371 | |
| 6372 { | |
| 6373 SweepClosure sweepClosure(this, gen, &_markBitMap, | |
| 6374 CMSYield && asynch); | |
| 6375 gen->cmsSpace()->blk_iterate_careful(&sweepClosure); | |
| 6376 // We need to free-up/coalesce garbage/blocks from a | |
| 6377 // co-terminal free run. This is done in the SweepClosure | |
| 6378 // destructor; so, do not remove this scope, else the | |
| 6379 // end-of-sweep-census below will be off by a little bit. | |
| 6380 } | |
| 6381 gen->cmsSpace()->sweep_completed(); | |
|
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|
6382 gen->cmsSpace()->endSweepFLCensus(sweep_count()); |
|
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|
6383 if (should_unload_classes()) { // unloaded classes this cycle, |
|
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|
6384 _concurrent_cycles_since_last_unload = 0; // ... reset count |
|
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|
6385 } else { // did not unload classes, |
|
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|
6386 _concurrent_cycles_since_last_unload++; // ... increment count |
|
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|
6387 } |
| 0 | 6388 } |
| 6389 | |
| 6390 // Reset CMS data structures (for now just the marking bit map) | |
| 6391 // preparatory for the next cycle. | |
| 6392 void CMSCollector::reset(bool asynch) { | |
| 6393 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 6394 CMSAdaptiveSizePolicy* sp = size_policy(); | |
| 6395 AdaptiveSizePolicyOutput(sp, gch->total_collections()); | |
| 6396 if (asynch) { | |
| 6397 CMSTokenSyncWithLocks ts(true, bitMapLock()); | |
| 6398 | |
| 6399 // If the state is not "Resetting", the foreground thread | |
| 6400 // has done a collection and the resetting. | |
| 6401 if (_collectorState != Resetting) { | |
| 6402 assert(_collectorState == Idling, "The state should only change" | |
| 6403 " because the foreground collector has finished the collection"); | |
| 6404 return; | |
| 6405 } | |
| 6406 | |
| 6407 // Clear the mark bitmap (no grey objects to start with) | |
| 6408 // for the next cycle. | |
| 6409 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
| 6410 CMSPhaseAccounting cmspa(this, "reset", !PrintGCDetails); | |
| 6411 | |
| 6412 HeapWord* curAddr = _markBitMap.startWord(); | |
| 6413 while (curAddr < _markBitMap.endWord()) { | |
| 6414 size_t remaining = pointer_delta(_markBitMap.endWord(), curAddr); | |
| 6415 MemRegion chunk(curAddr, MIN2(CMSBitMapYieldQuantum, remaining)); | |
| 6416 _markBitMap.clear_large_range(chunk); | |
| 6417 if (ConcurrentMarkSweepThread::should_yield() && | |
| 6418 !foregroundGCIsActive() && | |
| 6419 CMSYield) { | |
| 6420 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 6421 "CMS thread should hold CMS token"); | |
| 6422 assert_lock_strong(bitMapLock()); | |
| 6423 bitMapLock()->unlock(); | |
| 6424 ConcurrentMarkSweepThread::desynchronize(true); | |
| 6425 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 6426 stopTimer(); | |
| 6427 if (PrintCMSStatistics != 0) { | |
| 6428 incrementYields(); | |
| 6429 } | |
| 6430 icms_wait(); | |
| 6431 | |
| 6432 // See the comment in coordinator_yield() | |
| 6433 for (unsigned i = 0; i < CMSYieldSleepCount && | |
|
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diff
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|
6434 ConcurrentMarkSweepThread::should_yield() && |
|
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94
diff
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|
6435 !CMSCollector::foregroundGCIsActive(); ++i) { |
| 0 | 6436 os::sleep(Thread::current(), 1, false); |
| 6437 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 6438 } | |
| 6439 | |
| 6440 ConcurrentMarkSweepThread::synchronize(true); | |
| 6441 bitMapLock()->lock_without_safepoint_check(); | |
| 6442 startTimer(); | |
| 6443 } | |
| 6444 curAddr = chunk.end(); | |
| 6445 } | |
|
1387
0bfd3fb24150
6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
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1289
diff
changeset
|
6446 // A successful mostly concurrent collection has been done. |
|
0bfd3fb24150
6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
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1289
diff
changeset
|
6447 // Because only the full (i.e., concurrent mode failure) collections |
|
0bfd3fb24150
6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
jmasa
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1289
diff
changeset
|
6448 // are being measured for gc overhead limits, clean the "near" flag |
|
0bfd3fb24150
6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
jmasa
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1289
diff
changeset
|
6449 // and count. |
|
0bfd3fb24150
6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
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diff
changeset
|
6450 sp->reset_gc_overhead_limit_count(); |
| 0 | 6451 _collectorState = Idling; |
| 6452 } else { | |
| 6453 // already have the lock | |
| 6454 assert(_collectorState == Resetting, "just checking"); | |
| 6455 assert_lock_strong(bitMapLock()); | |
| 6456 _markBitMap.clear_all(); | |
| 6457 _collectorState = Idling; | |
| 6458 } | |
| 6459 | |
| 6460 // Stop incremental mode after a cycle completes, so that any future cycles | |
| 6461 // are triggered by allocation. | |
| 6462 stop_icms(); | |
| 6463 | |
| 6464 NOT_PRODUCT( | |
| 6465 if (RotateCMSCollectionTypes) { | |
| 6466 _cmsGen->rotate_debug_collection_type(); | |
| 6467 } | |
| 6468 ) | |
| 10405 | 6469 |
| 6470 register_gc_end(); | |
| 0 | 6471 } |
| 6472 | |
|
6064
9d679effd28c
7166894: Add gc cause to GC logging for all collectors
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6028
diff
changeset
|
6473 void CMSCollector::do_CMS_operation(CMS_op_type op, GCCause::Cause gc_cause) { |
| 0 | 6474 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps); |
| 6475 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
| 10405 | 6476 GCTraceTime t(GCCauseString("GC", gc_cause), PrintGC, !PrintGCDetails, NULL); |
| 0 | 6477 TraceCollectorStats tcs(counters()); |
| 6478 | |
| 6479 switch (op) { | |
| 6480 case CMS_op_checkpointRootsInitial: { | |
|
2125
7246a374a9f2
6458402: 3 jvmti tests fail with CMS and +ExplicitGCInvokesConcurrent
kamg
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1994
diff
changeset
|
6481 SvcGCMarker sgcm(SvcGCMarker::OTHER); |
| 0 | 6482 checkpointRootsInitial(true); // asynch |
| 6483 if (PrintGC) { | |
| 6484 _cmsGen->printOccupancy("initial-mark"); | |
| 6485 } | |
| 6486 break; | |
| 6487 } | |
| 6488 case CMS_op_checkpointRootsFinal: { | |
|
2125
7246a374a9f2
6458402: 3 jvmti tests fail with CMS and +ExplicitGCInvokesConcurrent
kamg
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1994
diff
changeset
|
6489 SvcGCMarker sgcm(SvcGCMarker::OTHER); |
| 0 | 6490 checkpointRootsFinal(true, // asynch |
| 6491 false, // !clear_all_soft_refs | |
| 6492 false); // !init_mark_was_synchronous | |
| 6493 if (PrintGC) { | |
| 6494 _cmsGen->printOccupancy("remark"); | |
| 6495 } | |
| 6496 break; | |
| 6497 } | |
| 6498 default: | |
| 6499 fatal("No such CMS_op"); | |
| 6500 } | |
| 6501 } | |
| 6502 | |
| 6503 #ifndef PRODUCT | |
| 6504 size_t const CMSCollector::skip_header_HeapWords() { | |
| 6505 return FreeChunk::header_size(); | |
| 6506 } | |
| 6507 | |
| 6508 // Try and collect here conditions that should hold when | |
| 6509 // CMS thread is exiting. The idea is that the foreground GC | |
| 6510 // thread should not be blocked if it wants to terminate | |
| 6511 // the CMS thread and yet continue to run the VM for a while | |
| 6512 // after that. | |
| 6513 void CMSCollector::verify_ok_to_terminate() const { | |
| 6514 assert(Thread::current()->is_ConcurrentGC_thread(), | |
| 6515 "should be called by CMS thread"); | |
| 6516 assert(!_foregroundGCShouldWait, "should be false"); | |
| 6517 // We could check here that all the various low-level locks | |
| 6518 // are not held by the CMS thread, but that is overkill; see | |
| 6519 // also CMSThread::verify_ok_to_terminate() where the CGC_lock | |
| 6520 // is checked. | |
| 6521 } | |
| 6522 #endif | |
| 6523 | |
| 6524 size_t CMSCollector::block_size_using_printezis_bits(HeapWord* addr) const { | |
|
453
c96030fff130
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452
diff
changeset
|
6525 assert(_markBitMap.isMarked(addr) && _markBitMap.isMarked(addr + 1), |
|
c96030fff130
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452
diff
changeset
|
6526 "missing Printezis mark?"); |
| 0 | 6527 HeapWord* nextOneAddr = _markBitMap.getNextMarkedWordAddress(addr + 2); |
| 6528 size_t size = pointer_delta(nextOneAddr + 1, addr); | |
| 6529 assert(size == CompactibleFreeListSpace::adjustObjectSize(size), | |
| 6530 "alignment problem"); | |
| 6531 assert(size >= 3, "Necessary for Printezis marks to work"); | |
| 6532 return size; | |
| 6533 } | |
| 6534 | |
| 6535 // A variant of the above (block_size_using_printezis_bits()) except | |
| 6536 // that we return 0 if the P-bits are not yet set. | |
| 6537 size_t CMSCollector::block_size_if_printezis_bits(HeapWord* addr) const { | |
|
2226
c5a923563727
6912621: iCMS: Error: assert(_markBitMap.isMarked(addr + 1),"Missing Printezis bit?")
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parents:
2177
diff
changeset
|
6538 if (_markBitMap.isMarked(addr + 1)) { |
|
c5a923563727
6912621: iCMS: Error: assert(_markBitMap.isMarked(addr + 1),"Missing Printezis bit?")
ysr
parents:
2177
diff
changeset
|
6539 assert(_markBitMap.isMarked(addr), "P-bit can be set only for marked objects"); |
| 0 | 6540 HeapWord* nextOneAddr = _markBitMap.getNextMarkedWordAddress(addr + 2); |
| 6541 size_t size = pointer_delta(nextOneAddr + 1, addr); | |
| 6542 assert(size == CompactibleFreeListSpace::adjustObjectSize(size), | |
| 6543 "alignment problem"); | |
| 6544 assert(size >= 3, "Necessary for Printezis marks to work"); | |
| 6545 return size; | |
|
2226
c5a923563727
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ysr
parents:
2177
diff
changeset
|
6546 } |
|
c5a923563727
6912621: iCMS: Error: assert(_markBitMap.isMarked(addr + 1),"Missing Printezis bit?")
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parents:
2177
diff
changeset
|
6547 return 0; |
| 0 | 6548 } |
| 6549 | |
| 6550 HeapWord* CMSCollector::next_card_start_after_block(HeapWord* addr) const { | |
| 6551 size_t sz = 0; | |
| 6552 oop p = (oop)addr; | |
|
6725
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diff
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|
6553 if (p->klass_or_null() != NULL) { |
| 0 | 6554 sz = CompactibleFreeListSpace::adjustObjectSize(p->size()); |
| 6555 } else { | |
| 6556 sz = block_size_using_printezis_bits(addr); | |
| 6557 } | |
| 6558 assert(sz > 0, "size must be nonzero"); | |
| 6559 HeapWord* next_block = addr + sz; | |
| 6560 HeapWord* next_card = (HeapWord*)round_to((uintptr_t)next_block, | |
| 6561 CardTableModRefBS::card_size); | |
| 6562 assert(round_down((uintptr_t)addr, CardTableModRefBS::card_size) < | |
| 6563 round_down((uintptr_t)next_card, CardTableModRefBS::card_size), | |
| 6564 "must be different cards"); | |
| 6565 return next_card; | |
| 6566 } | |
| 6567 | |
| 6568 | |
| 6569 // CMS Bit Map Wrapper ///////////////////////////////////////// | |
| 6570 | |
| 6571 // Construct a CMS bit map infrastructure, but don't create the | |
| 6572 // bit vector itself. That is done by a separate call CMSBitMap::allocate() | |
| 6573 // further below. | |
| 6574 CMSBitMap::CMSBitMap(int shifter, int mutex_rank, const char* mutex_name): | |
|
342
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143
diff
changeset
|
6575 _bm(), |
| 0 | 6576 _shifter(shifter), |
| 6577 _lock(mutex_rank >= 0 ? new Mutex(mutex_rank, mutex_name, true) : NULL) | |
| 6578 { | |
| 6579 _bmStartWord = 0; | |
| 6580 _bmWordSize = 0; | |
| 6581 } | |
| 6582 | |
| 6583 bool CMSBitMap::allocate(MemRegion mr) { | |
| 6584 _bmStartWord = mr.start(); | |
| 6585 _bmWordSize = mr.word_size(); | |
| 6586 ReservedSpace brs(ReservedSpace::allocation_align_size_up( | |
| 6587 (_bmWordSize >> (_shifter + LogBitsPerByte)) + 1)); | |
| 6588 if (!brs.is_reserved()) { | |
| 6589 warning("CMS bit map allocation failure"); | |
| 6590 return false; | |
| 6591 } | |
| 6592 // For now we'll just commit all of the bit map up fromt. | |
| 6593 // Later on we'll try to be more parsimonious with swap. | |
| 6594 if (!_virtual_space.initialize(brs, brs.size())) { | |
| 6595 warning("CMS bit map backing store failure"); | |
| 6596 return false; | |
| 6597 } | |
| 6598 assert(_virtual_space.committed_size() == brs.size(), | |
| 6599 "didn't reserve backing store for all of CMS bit map?"); | |
|
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diff
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|
6600 _bm.set_map((BitMap::bm_word_t*)_virtual_space.low()); |
| 0 | 6601 assert(_virtual_space.committed_size() << (_shifter + LogBitsPerByte) >= |
| 6602 _bmWordSize, "inconsistency in bit map sizing"); | |
| 6603 _bm.set_size(_bmWordSize >> _shifter); | |
| 6604 | |
| 6605 // bm.clear(); // can we rely on getting zero'd memory? verify below | |
| 6606 assert(isAllClear(), | |
| 6607 "Expected zero'd memory from ReservedSpace constructor"); | |
| 6608 assert(_bm.size() == heapWordDiffToOffsetDiff(sizeInWords()), | |
| 6609 "consistency check"); | |
| 6610 return true; | |
| 6611 } | |
| 6612 | |
| 6613 void CMSBitMap::dirty_range_iterate_clear(MemRegion mr, MemRegionClosure* cl) { | |
| 6614 HeapWord *next_addr, *end_addr, *last_addr; | |
| 6615 assert_locked(); | |
| 6616 assert(covers(mr), "out-of-range error"); | |
| 6617 // XXX assert that start and end are appropriately aligned | |
| 6618 for (next_addr = mr.start(), end_addr = mr.end(); | |
| 6619 next_addr < end_addr; next_addr = last_addr) { | |
| 6620 MemRegion dirty_region = getAndClearMarkedRegion(next_addr, end_addr); | |
| 6621 last_addr = dirty_region.end(); | |
| 6622 if (!dirty_region.is_empty()) { | |
| 6623 cl->do_MemRegion(dirty_region); | |
| 6624 } else { | |
| 6625 assert(last_addr == end_addr, "program logic"); | |
| 6626 return; | |
| 6627 } | |
| 6628 } | |
| 6629 } | |
| 6630 | |
|
9076
7b835924c31c
8011872: Include Bit Map addresses in the hs_err files
stefank
parents:
9072
diff
changeset
|
6631 void CMSBitMap::print_on_error(outputStream* st, const char* prefix) const { |
|
7b835924c31c
8011872: Include Bit Map addresses in the hs_err files
stefank
parents:
9072
diff
changeset
|
6632 _bm.print_on_error(st, prefix); |
|
7b835924c31c
8011872: Include Bit Map addresses in the hs_err files
stefank
parents:
9072
diff
changeset
|
6633 } |
|
7b835924c31c
8011872: Include Bit Map addresses in the hs_err files
stefank
parents:
9072
diff
changeset
|
6634 |
| 0 | 6635 #ifndef PRODUCT |
| 6636 void CMSBitMap::assert_locked() const { | |
| 6637 CMSLockVerifier::assert_locked(lock()); | |
| 6638 } | |
| 6639 | |
| 6640 bool CMSBitMap::covers(MemRegion mr) const { | |
| 6641 // assert(_bm.map() == _virtual_space.low(), "map inconsistency"); | |
| 6642 assert((size_t)_bm.size() == (_bmWordSize >> _shifter), | |
| 6643 "size inconsistency"); | |
| 6644 return (mr.start() >= _bmStartWord) && | |
| 6645 (mr.end() <= endWord()); | |
| 6646 } | |
| 6647 | |
| 6648 bool CMSBitMap::covers(HeapWord* start, size_t size) const { | |
| 6649 return (start >= _bmStartWord && (start + size) <= endWord()); | |
| 6650 } | |
| 6651 | |
| 6652 void CMSBitMap::verifyNoOneBitsInRange(HeapWord* left, HeapWord* right) { | |
| 6653 // verify that there are no 1 bits in the interval [left, right) | |
| 6654 FalseBitMapClosure falseBitMapClosure; | |
| 6655 iterate(&falseBitMapClosure, left, right); | |
| 6656 } | |
| 6657 | |
| 6658 void CMSBitMap::region_invariant(MemRegion mr) | |
| 6659 { | |
| 6660 assert_locked(); | |
| 6661 // mr = mr.intersection(MemRegion(_bmStartWord, _bmWordSize)); | |
| 6662 assert(!mr.is_empty(), "unexpected empty region"); | |
| 6663 assert(covers(mr), "mr should be covered by bit map"); | |
| 6664 // convert address range into offset range | |
| 6665 size_t start_ofs = heapWordToOffset(mr.start()); | |
| 6666 // Make sure that end() is appropriately aligned | |
| 6667 assert(mr.end() == (HeapWord*)round_to((intptr_t)mr.end(), | |
| 6668 (1 << (_shifter+LogHeapWordSize))), | |
| 6669 "Misaligned mr.end()"); | |
| 6670 size_t end_ofs = heapWordToOffset(mr.end()); | |
| 6671 assert(end_ofs > start_ofs, "Should mark at least one bit"); | |
| 6672 } | |
| 6673 | |
| 6674 #endif | |
| 6675 | |
| 6676 bool CMSMarkStack::allocate(size_t size) { | |
| 6677 // allocate a stack of the requisite depth | |
| 6678 ReservedSpace rs(ReservedSpace::allocation_align_size_up( | |
| 6679 size * sizeof(oop))); | |
| 6680 if (!rs.is_reserved()) { | |
| 6681 warning("CMSMarkStack allocation failure"); | |
| 6682 return false; | |
| 6683 } | |
| 6684 if (!_virtual_space.initialize(rs, rs.size())) { | |
| 6685 warning("CMSMarkStack backing store failure"); | |
| 6686 return false; | |
| 6687 } | |
| 6688 assert(_virtual_space.committed_size() == rs.size(), | |
| 6689 "didn't reserve backing store for all of CMS stack?"); | |
| 6690 _base = (oop*)(_virtual_space.low()); | |
| 6691 _index = 0; | |
| 6692 _capacity = size; | |
| 6693 NOT_PRODUCT(_max_depth = 0); | |
| 6694 return true; | |
| 6695 } | |
| 6696 | |
| 6697 // XXX FIX ME !!! In the MT case we come in here holding a | |
| 6698 // leaf lock. For printing we need to take a further lock | |
| 6699 // which has lower rank. We need to recallibrate the two | |
| 6700 // lock-ranks involved in order to be able to rpint the | |
| 6701 // messages below. (Or defer the printing to the caller. | |
| 6702 // For now we take the expedient path of just disabling the | |
| 6703 // messages for the problematic case.) | |
| 6704 void CMSMarkStack::expand() { | |
| 1284 | 6705 assert(_capacity <= MarkStackSizeMax, "stack bigger than permitted"); |
| 6706 if (_capacity == MarkStackSizeMax) { | |
| 0 | 6707 if (_hit_limit++ == 0 && !CMSConcurrentMTEnabled && PrintGCDetails) { |
| 6708 // We print a warning message only once per CMS cycle. | |
| 6709 gclog_or_tty->print_cr(" (benign) Hit CMSMarkStack max size limit"); | |
| 6710 } | |
| 6711 return; | |
| 6712 } | |
| 6713 // Double capacity if possible | |
| 1284 | 6714 size_t new_capacity = MIN2(_capacity*2, MarkStackSizeMax); |
| 0 | 6715 // Do not give up existing stack until we have managed to |
| 6716 // get the double capacity that we desired. | |
| 6717 ReservedSpace rs(ReservedSpace::allocation_align_size_up( | |
| 6718 new_capacity * sizeof(oop))); | |
| 6719 if (rs.is_reserved()) { | |
| 6720 // Release the backing store associated with old stack | |
| 6721 _virtual_space.release(); | |
| 6722 // Reinitialize virtual space for new stack | |
| 6723 if (!_virtual_space.initialize(rs, rs.size())) { | |
| 6724 fatal("Not enough swap for expanded marking stack"); | |
| 6725 } | |
| 6726 _base = (oop*)(_virtual_space.low()); | |
| 6727 _index = 0; | |
| 6728 _capacity = new_capacity; | |
| 6729 } else if (_failed_double++ == 0 && !CMSConcurrentMTEnabled && PrintGCDetails) { | |
| 6730 // Failed to double capacity, continue; | |
| 6731 // we print a detail message only once per CMS cycle. | |
| 6732 gclog_or_tty->print(" (benign) Failed to expand marking stack from "SIZE_FORMAT"K to " | |
| 6733 SIZE_FORMAT"K", | |
| 6734 _capacity / K, new_capacity / K); | |
| 6735 } | |
| 6736 } | |
| 6737 | |
| 6738 | |
| 6739 // Closures | |
| 6740 // XXX: there seems to be a lot of code duplication here; | |
| 6741 // should refactor and consolidate common code. | |
| 6742 | |
| 6743 // This closure is used to mark refs into the CMS generation in | |
| 6744 // the CMS bit map. Called at the first checkpoint. This closure | |
| 6745 // assumes that we do not need to re-mark dirty cards; if the CMS | |
|
6725
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6197
diff
changeset
|
6746 // generation on which this is used is not an oldest |
| 0 | 6747 // generation then this will lose younger_gen cards! |
| 6748 | |
| 6749 MarkRefsIntoClosure::MarkRefsIntoClosure( | |
|
994
753cf9794df9
6885169: merge of 4957990 and 6863023 causes conflict on do_nmethods
jrose
parents:
993
diff
changeset
|
6750 MemRegion span, CMSBitMap* bitMap): |
| 0 | 6751 _span(span), |
|
994
753cf9794df9
6885169: merge of 4957990 and 6863023 causes conflict on do_nmethods
jrose
parents:
993
diff
changeset
|
6752 _bitMap(bitMap) |
| 0 | 6753 { |
| 6754 assert(_ref_processor == NULL, "deliberately left NULL"); | |
| 6755 assert(_bitMap->covers(_span), "_bitMap/_span mismatch"); | |
| 6756 } | |
| 6757 | |
|
113
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coleenp
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94
diff
changeset
|
6758 void MarkRefsIntoClosure::do_oop(oop obj) { |
| 0 | 6759 // if p points into _span, then mark corresponding bit in _markBitMap |
|
113
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coleenp
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94
diff
changeset
|
6760 assert(obj->is_oop(), "expected an oop"); |
|
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
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94
diff
changeset
|
6761 HeapWord* addr = (HeapWord*)obj; |
|
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
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94
diff
changeset
|
6762 if (_span.contains(addr)) { |
|
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6763 // this should be made more efficient |
|
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6764 _bitMap->mark(addr); |
|
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
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94
diff
changeset
|
6765 } |
|
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6766 } |
|
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6767 |
|
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6768 void MarkRefsIntoClosure::do_oop(oop* p) { MarkRefsIntoClosure::do_oop_work(p); } |
|
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
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94
diff
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|
6769 void MarkRefsIntoClosure::do_oop(narrowOop* p) { MarkRefsIntoClosure::do_oop_work(p); } |
| 0 | 6770 |
| 6771 // A variant of the above, used for CMS marking verification. | |
| 6772 MarkRefsIntoVerifyClosure::MarkRefsIntoVerifyClosure( | |
|
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6773 MemRegion span, CMSBitMap* verification_bm, CMSBitMap* cms_bm): |
| 0 | 6774 _span(span), |
| 6775 _verification_bm(verification_bm), | |
|
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6776 _cms_bm(cms_bm) |
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6777 { |
| 0 | 6778 assert(_ref_processor == NULL, "deliberately left NULL"); |
| 6779 assert(_verification_bm->covers(_span), "_verification_bm/_span mismatch"); | |
| 6780 } | |
| 6781 | |
|
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6782 void MarkRefsIntoVerifyClosure::do_oop(oop obj) { |
| 0 | 6783 // if p points into _span, then mark corresponding bit in _markBitMap |
|
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6784 assert(obj->is_oop(), "expected an oop"); |
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6785 HeapWord* addr = (HeapWord*)obj; |
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6786 if (_span.contains(addr)) { |
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6787 _verification_bm->mark(addr); |
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6788 if (!_cms_bm->isMarked(addr)) { |
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6789 oop(addr)->print(); |
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6790 gclog_or_tty->print_cr(" (" INTPTR_FORMAT " should have been marked)", addr); |
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6791 fatal("... aborting"); |
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6792 } |
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6793 } |
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6794 } |
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6795 |
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6796 void MarkRefsIntoVerifyClosure::do_oop(oop* p) { MarkRefsIntoVerifyClosure::do_oop_work(p); } |
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6797 void MarkRefsIntoVerifyClosure::do_oop(narrowOop* p) { MarkRefsIntoVerifyClosure::do_oop_work(p); } |
| 0 | 6798 |
| 6799 ////////////////////////////////////////////////// | |
| 6800 // MarkRefsIntoAndScanClosure | |
| 6801 ////////////////////////////////////////////////// | |
| 6802 | |
| 6803 MarkRefsIntoAndScanClosure::MarkRefsIntoAndScanClosure(MemRegion span, | |
| 6804 ReferenceProcessor* rp, | |
| 6805 CMSBitMap* bit_map, | |
| 6806 CMSBitMap* mod_union_table, | |
| 6807 CMSMarkStack* mark_stack, | |
| 6808 CMSCollector* collector, | |
| 6809 bool should_yield, | |
| 6810 bool concurrent_precleaning): | |
| 6811 _collector(collector), | |
| 6812 _span(span), | |
| 6813 _bit_map(bit_map), | |
| 6814 _mark_stack(mark_stack), | |
| 6815 _pushAndMarkClosure(collector, span, rp, bit_map, mod_union_table, | |
|
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6816 mark_stack, concurrent_precleaning), |
| 0 | 6817 _yield(should_yield), |
| 6818 _concurrent_precleaning(concurrent_precleaning), | |
| 6819 _freelistLock(NULL) | |
| 6820 { | |
| 6821 _ref_processor = rp; | |
| 6822 assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL"); | |
| 6823 } | |
| 6824 | |
| 6825 // This closure is used to mark refs into the CMS generation at the | |
| 6826 // second (final) checkpoint, and to scan and transitively follow | |
| 6827 // the unmarked oops. It is also used during the concurrent precleaning | |
| 6828 // phase while scanning objects on dirty cards in the CMS generation. | |
| 6829 // The marks are made in the marking bit map and the marking stack is | |
| 6830 // used for keeping the (newly) grey objects during the scan. | |
| 6831 // The parallel version (Par_...) appears further below. | |
|
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6832 void MarkRefsIntoAndScanClosure::do_oop(oop obj) { |
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6833 if (obj != NULL) { |
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6834 assert(obj->is_oop(), "expected an oop"); |
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6835 HeapWord* addr = (HeapWord*)obj; |
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6836 assert(_mark_stack->isEmpty(), "pre-condition (eager drainage)"); |
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6837 assert(_collector->overflow_list_is_empty(), |
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6838 "overflow list should be empty"); |
| 0 | 6839 if (_span.contains(addr) && |
| 6840 !_bit_map->isMarked(addr)) { | |
| 6841 // mark bit map (object is now grey) | |
| 6842 _bit_map->mark(addr); | |
| 6843 // push on marking stack (stack should be empty), and drain the | |
| 6844 // stack by applying this closure to the oops in the oops popped | |
| 6845 // from the stack (i.e. blacken the grey objects) | |
|
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6846 bool res = _mark_stack->push(obj); |
| 0 | 6847 assert(res, "Should have space to push on empty stack"); |
| 6848 do { | |
| 6849 oop new_oop = _mark_stack->pop(); | |
| 6850 assert(new_oop != NULL && new_oop->is_oop(), "Expected an oop"); | |
| 6851 assert(_bit_map->isMarked((HeapWord*)new_oop), | |
| 6852 "only grey objects on this stack"); | |
| 6853 // iterate over the oops in this oop, marking and pushing | |
| 6854 // the ones in CMS heap (i.e. in _span). | |
| 6855 new_oop->oop_iterate(&_pushAndMarkClosure); | |
| 6856 // check if it's time to yield | |
| 6857 do_yield_check(); | |
| 6858 } while (!_mark_stack->isEmpty() || | |
| 6859 (!_concurrent_precleaning && take_from_overflow_list())); | |
| 6860 // if marking stack is empty, and we are not doing this | |
| 6861 // during precleaning, then check the overflow list | |
| 6862 } | |
| 6863 assert(_mark_stack->isEmpty(), "post-condition (eager drainage)"); | |
| 6864 assert(_collector->overflow_list_is_empty(), | |
| 6865 "overflow list was drained above"); | |
| 6866 // We could restore evacuated mark words, if any, used for | |
| 6867 // overflow list links here because the overflow list is | |
| 6868 // provably empty here. That would reduce the maximum | |
| 6869 // size requirements for preserved_{oop,mark}_stack. | |
| 6870 // But we'll just postpone it until we are all done | |
| 6871 // so we can just stream through. | |
| 6872 if (!_concurrent_precleaning && CMSOverflowEarlyRestoration) { | |
| 6873 _collector->restore_preserved_marks_if_any(); | |
| 6874 assert(_collector->no_preserved_marks(), "No preserved marks"); | |
| 6875 } | |
| 6876 assert(!CMSOverflowEarlyRestoration || _collector->no_preserved_marks(), | |
| 6877 "All preserved marks should have been restored above"); | |
| 6878 } | |
| 6879 } | |
| 6880 | |
|
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6881 void MarkRefsIntoAndScanClosure::do_oop(oop* p) { MarkRefsIntoAndScanClosure::do_oop_work(p); } |
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6882 void MarkRefsIntoAndScanClosure::do_oop(narrowOop* p) { MarkRefsIntoAndScanClosure::do_oop_work(p); } |
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6883 |
| 0 | 6884 void MarkRefsIntoAndScanClosure::do_yield_work() { |
| 6885 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 6886 "CMS thread should hold CMS token"); | |
| 6887 assert_lock_strong(_freelistLock); | |
| 6888 assert_lock_strong(_bit_map->lock()); | |
| 6889 // relinquish the free_list_lock and bitMaplock() | |
| 6890 _bit_map->lock()->unlock(); | |
| 6891 _freelistLock->unlock(); | |
| 6892 ConcurrentMarkSweepThread::desynchronize(true); | |
| 6893 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 6894 _collector->stopTimer(); | |
| 6895 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 6896 if (PrintCMSStatistics != 0) { | |
| 6897 _collector->incrementYields(); | |
| 6898 } | |
| 6899 _collector->icms_wait(); | |
| 6900 | |
| 6901 // See the comment in coordinator_yield() | |
|
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6902 for (unsigned i = 0; |
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6903 i < CMSYieldSleepCount && |
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6904 ConcurrentMarkSweepThread::should_yield() && |
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6905 !CMSCollector::foregroundGCIsActive(); |
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6906 ++i) { |
| 0 | 6907 os::sleep(Thread::current(), 1, false); |
| 6908 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 6909 } | |
| 6910 | |
| 6911 ConcurrentMarkSweepThread::synchronize(true); | |
| 6912 _freelistLock->lock_without_safepoint_check(); | |
| 6913 _bit_map->lock()->lock_without_safepoint_check(); | |
| 6914 _collector->startTimer(); | |
| 6915 } | |
| 6916 | |
| 6917 /////////////////////////////////////////////////////////// | |
| 6918 // Par_MarkRefsIntoAndScanClosure: a parallel version of | |
| 6919 // MarkRefsIntoAndScanClosure | |
| 6920 /////////////////////////////////////////////////////////// | |
| 6921 Par_MarkRefsIntoAndScanClosure::Par_MarkRefsIntoAndScanClosure( | |
| 6922 CMSCollector* collector, MemRegion span, ReferenceProcessor* rp, | |
|
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6923 CMSBitMap* bit_map, OopTaskQueue* work_queue): |
| 0 | 6924 _span(span), |
| 6925 _bit_map(bit_map), | |
| 6926 _work_queue(work_queue), | |
| 6927 _low_water_mark(MIN2((uint)(work_queue->max_elems()/4), | |
| 6928 (uint)(CMSWorkQueueDrainThreshold * ParallelGCThreads))), | |
|
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6929 _par_pushAndMarkClosure(collector, span, rp, bit_map, work_queue) |
| 0 | 6930 { |
| 6931 _ref_processor = rp; | |
| 6932 assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL"); | |
| 6933 } | |
| 6934 | |
| 6935 // This closure is used to mark refs into the CMS generation at the | |
| 6936 // second (final) checkpoint, and to scan and transitively follow | |
| 6937 // the unmarked oops. The marks are made in the marking bit map and | |
| 6938 // the work_queue is used for keeping the (newly) grey objects during | |
| 6939 // the scan phase whence they are also available for stealing by parallel | |
| 6940 // threads. Since the marking bit map is shared, updates are | |
| 6941 // synchronized (via CAS). | |
|
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6942 void Par_MarkRefsIntoAndScanClosure::do_oop(oop obj) { |
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6943 if (obj != NULL) { |
| 0 | 6944 // Ignore mark word because this could be an already marked oop |
| 6945 // that may be chained at the end of the overflow list. | |
|
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6946 assert(obj->is_oop(true), "expected an oop"); |
|
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6947 HeapWord* addr = (HeapWord*)obj; |
| 0 | 6948 if (_span.contains(addr) && |
| 6949 !_bit_map->isMarked(addr)) { | |
| 6950 // mark bit map (object will become grey): | |
| 6951 // It is possible for several threads to be | |
| 6952 // trying to "claim" this object concurrently; | |
| 6953 // the unique thread that succeeds in marking the | |
| 6954 // object first will do the subsequent push on | |
| 6955 // to the work queue (or overflow list). | |
| 6956 if (_bit_map->par_mark(addr)) { | |
| 6957 // push on work_queue (which may not be empty), and trim the | |
| 6958 // queue to an appropriate length by applying this closure to | |
| 6959 // the oops in the oops popped from the stack (i.e. blacken the | |
| 6960 // grey objects) | |
|
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6961 bool res = _work_queue->push(obj); |
| 0 | 6962 assert(res, "Low water mark should be less than capacity?"); |
| 6963 trim_queue(_low_water_mark); | |
| 6964 } // Else, another thread claimed the object | |
| 6965 } | |
| 6966 } | |
| 6967 } | |
| 6968 | |
|
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6969 void Par_MarkRefsIntoAndScanClosure::do_oop(oop* p) { Par_MarkRefsIntoAndScanClosure::do_oop_work(p); } |
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6970 void Par_MarkRefsIntoAndScanClosure::do_oop(narrowOop* p) { Par_MarkRefsIntoAndScanClosure::do_oop_work(p); } |
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6971 |
| 0 | 6972 // This closure is used to rescan the marked objects on the dirty cards |
| 6973 // in the mod union table and the card table proper. | |
| 6974 size_t ScanMarkedObjectsAgainCarefullyClosure::do_object_careful_m( | |
| 6975 oop p, MemRegion mr) { | |
| 6976 | |
| 6977 size_t size = 0; | |
| 6978 HeapWord* addr = (HeapWord*)p; | |
| 6979 DEBUG_ONLY(_collector->verify_work_stacks_empty();) | |
| 6980 assert(_span.contains(addr), "we are scanning the CMS generation"); | |
| 6981 // check if it's time to yield | |
| 6982 if (do_yield_check()) { | |
| 6983 // We yielded for some foreground stop-world work, | |
| 6984 // and we have been asked to abort this ongoing preclean cycle. | |
| 6985 return 0; | |
| 6986 } | |
| 6987 if (_bitMap->isMarked(addr)) { | |
| 6988 // it's marked; is it potentially uninitialized? | |
| 187 | 6989 if (p->klass_or_null() != NULL) { |
| 0 | 6990 // an initialized object; ignore mark word in verification below |
| 6991 // since we are running concurrent with mutators | |
| 6992 assert(p->is_oop(true), "should be an oop"); | |
| 6993 if (p->is_objArray()) { | |
| 6994 // objArrays are precisely marked; restrict scanning | |
| 6995 // to dirty cards only. | |
| 187 | 6996 size = CompactibleFreeListSpace::adjustObjectSize( |
| 6997 p->oop_iterate(_scanningClosure, mr)); | |
| 0 | 6998 } else { |
| 6999 // A non-array may have been imprecisely marked; we need | |
| 7000 // to scan object in its entirety. | |
| 7001 size = CompactibleFreeListSpace::adjustObjectSize( | |
| 7002 p->oop_iterate(_scanningClosure)); | |
| 7003 } | |
| 9152 | 7004 #ifdef ASSERT |
| 0 | 7005 size_t direct_size = |
| 7006 CompactibleFreeListSpace::adjustObjectSize(p->size()); | |
| 7007 assert(size == direct_size, "Inconsistency in size"); | |
| 7008 assert(size >= 3, "Necessary for Printezis marks to work"); | |
| 7009 if (!_bitMap->isMarked(addr+1)) { | |
| 7010 _bitMap->verifyNoOneBitsInRange(addr+2, addr+size); | |
| 7011 } else { | |
| 7012 _bitMap->verifyNoOneBitsInRange(addr+2, addr+size-1); | |
| 7013 assert(_bitMap->isMarked(addr+size-1), | |
| 7014 "inconsistent Printezis mark"); | |
| 7015 } | |
| 9152 | 7016 #endif // ASSERT |
| 0 | 7017 } else { |
| 7018 // an unitialized object | |
| 7019 assert(_bitMap->isMarked(addr+1), "missing Printezis mark?"); | |
| 7020 HeapWord* nextOneAddr = _bitMap->getNextMarkedWordAddress(addr + 2); | |
| 7021 size = pointer_delta(nextOneAddr + 1, addr); | |
| 7022 assert(size == CompactibleFreeListSpace::adjustObjectSize(size), | |
| 7023 "alignment problem"); | |
| 7024 // Note that pre-cleaning needn't redirty the card. OopDesc::set_klass() | |
| 7025 // will dirty the card when the klass pointer is installed in the | |
| 7026 // object (signalling the completion of initialization). | |
| 7027 } | |
| 7028 } else { | |
| 7029 // Either a not yet marked object or an uninitialized object | |
|
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7030 if (p->klass_or_null() == NULL) { |
| 0 | 7031 // An uninitialized object, skip to the next card, since |
| 7032 // we may not be able to read its P-bits yet. | |
| 7033 assert(size == 0, "Initial value"); | |
| 7034 } else { | |
| 7035 // An object not (yet) reached by marking: we merely need to | |
| 7036 // compute its size so as to go look at the next block. | |
| 7037 assert(p->is_oop(true), "should be an oop"); | |
| 7038 size = CompactibleFreeListSpace::adjustObjectSize(p->size()); | |
| 7039 } | |
| 7040 } | |
| 7041 DEBUG_ONLY(_collector->verify_work_stacks_empty();) | |
| 7042 return size; | |
| 7043 } | |
| 7044 | |
| 7045 void ScanMarkedObjectsAgainCarefullyClosure::do_yield_work() { | |
| 7046 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 7047 "CMS thread should hold CMS token"); | |
| 7048 assert_lock_strong(_freelistLock); | |
| 7049 assert_lock_strong(_bitMap->lock()); | |
| 7050 // relinquish the free_list_lock and bitMaplock() | |
| 7051 _bitMap->lock()->unlock(); | |
| 7052 _freelistLock->unlock(); | |
| 7053 ConcurrentMarkSweepThread::desynchronize(true); | |
| 7054 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7055 _collector->stopTimer(); | |
| 7056 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 7057 if (PrintCMSStatistics != 0) { | |
| 7058 _collector->incrementYields(); | |
| 7059 } | |
| 7060 _collector->icms_wait(); | |
| 7061 | |
| 7062 // See the comment in coordinator_yield() | |
| 7063 for (unsigned i = 0; i < CMSYieldSleepCount && | |
|
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7064 ConcurrentMarkSweepThread::should_yield() && |
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7065 !CMSCollector::foregroundGCIsActive(); ++i) { |
| 0 | 7066 os::sleep(Thread::current(), 1, false); |
| 7067 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7068 } | |
| 7069 | |
| 7070 ConcurrentMarkSweepThread::synchronize(true); | |
| 7071 _freelistLock->lock_without_safepoint_check(); | |
| 7072 _bitMap->lock()->lock_without_safepoint_check(); | |
| 7073 _collector->startTimer(); | |
| 7074 } | |
| 7075 | |
| 7076 | |
| 7077 ////////////////////////////////////////////////////////////////// | |
| 7078 // SurvivorSpacePrecleanClosure | |
| 7079 ////////////////////////////////////////////////////////////////// | |
| 7080 // This (single-threaded) closure is used to preclean the oops in | |
| 7081 // the survivor spaces. | |
| 7082 size_t SurvivorSpacePrecleanClosure::do_object_careful(oop p) { | |
| 7083 | |
| 7084 HeapWord* addr = (HeapWord*)p; | |
| 7085 DEBUG_ONLY(_collector->verify_work_stacks_empty();) | |
| 7086 assert(!_span.contains(addr), "we are scanning the survivor spaces"); | |
| 187 | 7087 assert(p->klass_or_null() != NULL, "object should be initializd"); |
| 0 | 7088 // an initialized object; ignore mark word in verification below |
| 7089 // since we are running concurrent with mutators | |
| 7090 assert(p->is_oop(true), "should be an oop"); | |
| 7091 // Note that we do not yield while we iterate over | |
| 7092 // the interior oops of p, pushing the relevant ones | |
| 7093 // on our marking stack. | |
| 7094 size_t size = p->oop_iterate(_scanning_closure); | |
| 7095 do_yield_check(); | |
| 7096 // Observe that below, we do not abandon the preclean | |
| 7097 // phase as soon as we should; rather we empty the | |
| 7098 // marking stack before returning. This is to satisfy | |
| 7099 // some existing assertions. In general, it may be a | |
| 7100 // good idea to abort immediately and complete the marking | |
| 7101 // from the grey objects at a later time. | |
| 7102 while (!_mark_stack->isEmpty()) { | |
| 7103 oop new_oop = _mark_stack->pop(); | |
| 7104 assert(new_oop != NULL && new_oop->is_oop(), "Expected an oop"); | |
| 7105 assert(_bit_map->isMarked((HeapWord*)new_oop), | |
| 7106 "only grey objects on this stack"); | |
| 7107 // iterate over the oops in this oop, marking and pushing | |
| 7108 // the ones in CMS heap (i.e. in _span). | |
| 7109 new_oop->oop_iterate(_scanning_closure); | |
| 7110 // check if it's time to yield | |
| 7111 do_yield_check(); | |
| 7112 } | |
| 7113 unsigned int after_count = | |
| 7114 GenCollectedHeap::heap()->total_collections(); | |
| 7115 bool abort = (_before_count != after_count) || | |
| 7116 _collector->should_abort_preclean(); | |
| 7117 return abort ? 0 : size; | |
| 7118 } | |
| 7119 | |
| 7120 void SurvivorSpacePrecleanClosure::do_yield_work() { | |
| 7121 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 7122 "CMS thread should hold CMS token"); | |
| 7123 assert_lock_strong(_bit_map->lock()); | |
| 7124 // Relinquish the bit map lock | |
| 7125 _bit_map->lock()->unlock(); | |
| 7126 ConcurrentMarkSweepThread::desynchronize(true); | |
| 7127 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7128 _collector->stopTimer(); | |
| 7129 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 7130 if (PrintCMSStatistics != 0) { | |
| 7131 _collector->incrementYields(); | |
| 7132 } | |
| 7133 _collector->icms_wait(); | |
| 7134 | |
| 7135 // See the comment in coordinator_yield() | |
| 7136 for (unsigned i = 0; i < CMSYieldSleepCount && | |
| 7137 ConcurrentMarkSweepThread::should_yield() && | |
| 7138 !CMSCollector::foregroundGCIsActive(); ++i) { | |
| 7139 os::sleep(Thread::current(), 1, false); | |
| 7140 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7141 } | |
| 7142 | |
| 7143 ConcurrentMarkSweepThread::synchronize(true); | |
| 7144 _bit_map->lock()->lock_without_safepoint_check(); | |
| 7145 _collector->startTimer(); | |
| 7146 } | |
| 7147 | |
| 7148 // This closure is used to rescan the marked objects on the dirty cards | |
| 7149 // in the mod union table and the card table proper. In the parallel | |
| 7150 // case, although the bitMap is shared, we do a single read so the | |
| 7151 // isMarked() query is "safe". | |
| 7152 bool ScanMarkedObjectsAgainClosure::do_object_bm(oop p, MemRegion mr) { | |
| 7153 // Ignore mark word because we are running concurrent with mutators | |
| 7154 assert(p->is_oop_or_null(true), "expected an oop or null"); | |
| 7155 HeapWord* addr = (HeapWord*)p; | |
| 7156 assert(_span.contains(addr), "we are scanning the CMS generation"); | |
| 7157 bool is_obj_array = false; | |
| 9152 | 7158 #ifdef ASSERT |
| 0 | 7159 if (!_parallel) { |
| 7160 assert(_mark_stack->isEmpty(), "pre-condition (eager drainage)"); | |
| 7161 assert(_collector->overflow_list_is_empty(), | |
| 7162 "overflow list should be empty"); | |
| 7163 | |
| 7164 } | |
| 9152 | 7165 #endif // ASSERT |
| 0 | 7166 if (_bit_map->isMarked(addr)) { |
| 7167 // Obj arrays are precisely marked, non-arrays are not; | |
| 7168 // so we scan objArrays precisely and non-arrays in their | |
| 7169 // entirety. | |
| 7170 if (p->is_objArray()) { | |
| 7171 is_obj_array = true; | |
| 7172 if (_parallel) { | |
| 7173 p->oop_iterate(_par_scan_closure, mr); | |
| 7174 } else { | |
| 7175 p->oop_iterate(_scan_closure, mr); | |
| 7176 } | |
| 7177 } else { | |
| 7178 if (_parallel) { | |
| 7179 p->oop_iterate(_par_scan_closure); | |
| 7180 } else { | |
| 7181 p->oop_iterate(_scan_closure); | |
| 7182 } | |
| 7183 } | |
| 7184 } | |
| 9152 | 7185 #ifdef ASSERT |
| 0 | 7186 if (!_parallel) { |
| 7187 assert(_mark_stack->isEmpty(), "post-condition (eager drainage)"); | |
| 7188 assert(_collector->overflow_list_is_empty(), | |
| 7189 "overflow list should be empty"); | |
| 7190 | |
| 7191 } | |
| 9152 | 7192 #endif // ASSERT |
| 0 | 7193 return is_obj_array; |
| 7194 } | |
| 7195 | |
| 7196 MarkFromRootsClosure::MarkFromRootsClosure(CMSCollector* collector, | |
| 7197 MemRegion span, | |
| 7198 CMSBitMap* bitMap, CMSMarkStack* markStack, | |
| 7199 bool should_yield, bool verifying): | |
| 7200 _collector(collector), | |
| 7201 _span(span), | |
| 7202 _bitMap(bitMap), | |
| 7203 _mut(&collector->_modUnionTable), | |
| 7204 _markStack(markStack), | |
| 7205 _yield(should_yield), | |
| 7206 _skipBits(0) | |
| 7207 { | |
| 7208 assert(_markStack->isEmpty(), "stack should be empty"); | |
| 7209 _finger = _bitMap->startWord(); | |
| 7210 _threshold = _finger; | |
| 7211 assert(_collector->_restart_addr == NULL, "Sanity check"); | |
| 7212 assert(_span.contains(_finger), "Out of bounds _finger?"); | |
| 7213 DEBUG_ONLY(_verifying = verifying;) | |
| 7214 } | |
| 7215 | |
| 7216 void MarkFromRootsClosure::reset(HeapWord* addr) { | |
| 7217 assert(_markStack->isEmpty(), "would cause duplicates on stack"); | |
| 7218 assert(_span.contains(addr), "Out of bounds _finger?"); | |
| 7219 _finger = addr; | |
| 7220 _threshold = (HeapWord*)round_to( | |
| 7221 (intptr_t)_finger, CardTableModRefBS::card_size); | |
| 7222 } | |
| 7223 | |
| 7224 // Should revisit to see if this should be restructured for | |
| 7225 // greater efficiency. | |
|
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7226 bool MarkFromRootsClosure::do_bit(size_t offset) { |
| 0 | 7227 if (_skipBits > 0) { |
| 7228 _skipBits--; | |
|
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7229 return true; |
| 0 | 7230 } |
| 7231 // convert offset into a HeapWord* | |
| 7232 HeapWord* addr = _bitMap->startWord() + offset; | |
| 7233 assert(_bitMap->endWord() && addr < _bitMap->endWord(), | |
| 7234 "address out of range"); | |
| 7235 assert(_bitMap->isMarked(addr), "tautology"); | |
| 7236 if (_bitMap->isMarked(addr+1)) { | |
| 7237 // this is an allocated but not yet initialized object | |
| 7238 assert(_skipBits == 0, "tautology"); | |
| 7239 _skipBits = 2; // skip next two marked bits ("Printezis-marks") | |
| 7240 oop p = oop(addr); | |
|
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7241 if (p->klass_or_null() == NULL) { |
| 0 | 7242 DEBUG_ONLY(if (!_verifying) {) |
| 7243 // We re-dirty the cards on which this object lies and increase | |
| 7244 // the _threshold so that we'll come back to scan this object | |
| 7245 // during the preclean or remark phase. (CMSCleanOnEnter) | |
| 7246 if (CMSCleanOnEnter) { | |
| 7247 size_t sz = _collector->block_size_using_printezis_bits(addr); | |
| 7248 HeapWord* end_card_addr = (HeapWord*)round_to( | |
| 7249 (intptr_t)(addr+sz), CardTableModRefBS::card_size); | |
|
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7250 MemRegion redirty_range = MemRegion(addr, end_card_addr); |
| 0 | 7251 assert(!redirty_range.is_empty(), "Arithmetical tautology"); |
| 7252 // Bump _threshold to end_card_addr; note that | |
| 7253 // _threshold cannot possibly exceed end_card_addr, anyhow. | |
| 7254 // This prevents future clearing of the card as the scan proceeds | |
| 7255 // to the right. | |
| 7256 assert(_threshold <= end_card_addr, | |
| 7257 "Because we are just scanning into this object"); | |
| 7258 if (_threshold < end_card_addr) { | |
| 7259 _threshold = end_card_addr; | |
| 7260 } | |
| 187 | 7261 if (p->klass_or_null() != NULL) { |
| 0 | 7262 // Redirty the range of cards... |
| 7263 _mut->mark_range(redirty_range); | |
| 7264 } // ...else the setting of klass will dirty the card anyway. | |
| 7265 } | |
| 7266 DEBUG_ONLY(}) | |
|
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7267 return true; |
| 0 | 7268 } |
| 7269 } | |
| 7270 scanOopsInOop(addr); | |
|
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7271 return true; |
| 0 | 7272 } |
| 7273 | |
| 7274 // We take a break if we've been at this for a while, | |
| 7275 // so as to avoid monopolizing the locks involved. | |
| 7276 void MarkFromRootsClosure::do_yield_work() { | |
| 7277 // First give up the locks, then yield, then re-lock | |
| 7278 // We should probably use a constructor/destructor idiom to | |
| 7279 // do this unlock/lock or modify the MutexUnlocker class to | |
| 7280 // serve our purpose. XXX | |
| 7281 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 7282 "CMS thread should hold CMS token"); | |
| 7283 assert_lock_strong(_bitMap->lock()); | |
| 7284 _bitMap->lock()->unlock(); | |
| 7285 ConcurrentMarkSweepThread::desynchronize(true); | |
| 7286 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7287 _collector->stopTimer(); | |
| 7288 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 7289 if (PrintCMSStatistics != 0) { | |
| 7290 _collector->incrementYields(); | |
| 7291 } | |
| 7292 _collector->icms_wait(); | |
| 7293 | |
| 7294 // See the comment in coordinator_yield() | |
| 7295 for (unsigned i = 0; i < CMSYieldSleepCount && | |
| 7296 ConcurrentMarkSweepThread::should_yield() && | |
| 7297 !CMSCollector::foregroundGCIsActive(); ++i) { | |
| 7298 os::sleep(Thread::current(), 1, false); | |
| 7299 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7300 } | |
| 7301 | |
| 7302 ConcurrentMarkSweepThread::synchronize(true); | |
| 7303 _bitMap->lock()->lock_without_safepoint_check(); | |
| 7304 _collector->startTimer(); | |
| 7305 } | |
| 7306 | |
| 7307 void MarkFromRootsClosure::scanOopsInOop(HeapWord* ptr) { | |
| 7308 assert(_bitMap->isMarked(ptr), "expected bit to be set"); | |
| 7309 assert(_markStack->isEmpty(), | |
| 7310 "should drain stack to limit stack usage"); | |
| 7311 // convert ptr to an oop preparatory to scanning | |
|
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7312 oop obj = oop(ptr); |
| 0 | 7313 // Ignore mark word in verification below, since we |
| 7314 // may be running concurrent with mutators. | |
|
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7315 assert(obj->is_oop(true), "should be an oop"); |
| 0 | 7316 assert(_finger <= ptr, "_finger runneth ahead"); |
| 7317 // advance the finger to right end of this object | |
|
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7318 _finger = ptr + obj->size(); |
| 0 | 7319 assert(_finger > ptr, "we just incremented it above"); |
| 7320 // On large heaps, it may take us some time to get through | |
| 7321 // the marking phase (especially if running iCMS). During | |
| 7322 // this time it's possible that a lot of mutations have | |
| 7323 // accumulated in the card table and the mod union table -- | |
| 7324 // these mutation records are redundant until we have | |
| 7325 // actually traced into the corresponding card. | |
| 7326 // Here, we check whether advancing the finger would make | |
| 7327 // us cross into a new card, and if so clear corresponding | |
| 7328 // cards in the MUT (preclean them in the card-table in the | |
| 7329 // future). | |
| 7330 | |
| 7331 DEBUG_ONLY(if (!_verifying) {) | |
| 7332 // The clean-on-enter optimization is disabled by default, | |
| 7333 // until we fix 6178663. | |
| 7334 if (CMSCleanOnEnter && (_finger > _threshold)) { | |
| 7335 // [_threshold, _finger) represents the interval | |
| 7336 // of cards to be cleared in MUT (or precleaned in card table). | |
| 7337 // The set of cards to be cleared is all those that overlap | |
| 7338 // with the interval [_threshold, _finger); note that | |
| 7339 // _threshold is always kept card-aligned but _finger isn't | |
| 7340 // always card-aligned. | |
| 7341 HeapWord* old_threshold = _threshold; | |
| 7342 assert(old_threshold == (HeapWord*)round_to( | |
| 7343 (intptr_t)old_threshold, CardTableModRefBS::card_size), | |
| 7344 "_threshold should always be card-aligned"); | |
| 7345 _threshold = (HeapWord*)round_to( | |
| 7346 (intptr_t)_finger, CardTableModRefBS::card_size); | |
| 7347 MemRegion mr(old_threshold, _threshold); | |
| 7348 assert(!mr.is_empty(), "Control point invariant"); | |
| 7349 assert(_span.contains(mr), "Should clear within span"); | |
| 7350 _mut->clear_range(mr); | |
| 7351 } | |
| 7352 DEBUG_ONLY(}) | |
| 7353 // Note: the finger doesn't advance while we drain | |
| 7354 // the stack below. | |
| 7355 PushOrMarkClosure pushOrMarkClosure(_collector, | |
| 7356 _span, _bitMap, _markStack, | |
| 7357 _finger, this); | |
|
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7358 bool res = _markStack->push(obj); |
| 0 | 7359 assert(res, "Empty non-zero size stack should have space for single push"); |
| 7360 while (!_markStack->isEmpty()) { | |
| 7361 oop new_oop = _markStack->pop(); | |
| 7362 // Skip verifying header mark word below because we are | |
| 7363 // running concurrent with mutators. | |
| 7364 assert(new_oop->is_oop(true), "Oops! expected to pop an oop"); | |
| 7365 // now scan this oop's oops | |
| 7366 new_oop->oop_iterate(&pushOrMarkClosure); | |
| 7367 do_yield_check(); | |
| 7368 } | |
| 7369 assert(_markStack->isEmpty(), "tautology, emphasizing post-condition"); | |
| 7370 } | |
| 7371 | |
| 7372 Par_MarkFromRootsClosure::Par_MarkFromRootsClosure(CMSConcMarkingTask* task, | |
| 7373 CMSCollector* collector, MemRegion span, | |
| 7374 CMSBitMap* bit_map, | |
| 7375 OopTaskQueue* work_queue, | |
| 7376 CMSMarkStack* overflow_stack, | |
| 7377 bool should_yield): | |
| 7378 _collector(collector), | |
| 7379 _whole_span(collector->_span), | |
| 7380 _span(span), | |
| 7381 _bit_map(bit_map), | |
| 7382 _mut(&collector->_modUnionTable), | |
| 7383 _work_queue(work_queue), | |
| 7384 _overflow_stack(overflow_stack), | |
| 7385 _yield(should_yield), | |
| 7386 _skip_bits(0), | |
| 7387 _task(task) | |
| 7388 { | |
| 7389 assert(_work_queue->size() == 0, "work_queue should be empty"); | |
| 7390 _finger = span.start(); | |
| 7391 _threshold = _finger; // XXX Defer clear-on-enter optimization for now | |
| 7392 assert(_span.contains(_finger), "Out of bounds _finger?"); | |
| 7393 } | |
| 7394 | |
| 7395 // Should revisit to see if this should be restructured for | |
| 7396 // greater efficiency. | |
|
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7397 bool Par_MarkFromRootsClosure::do_bit(size_t offset) { |
| 0 | 7398 if (_skip_bits > 0) { |
| 7399 _skip_bits--; | |
|
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7400 return true; |
| 0 | 7401 } |
| 7402 // convert offset into a HeapWord* | |
| 7403 HeapWord* addr = _bit_map->startWord() + offset; | |
| 7404 assert(_bit_map->endWord() && addr < _bit_map->endWord(), | |
| 7405 "address out of range"); | |
| 7406 assert(_bit_map->isMarked(addr), "tautology"); | |
| 7407 if (_bit_map->isMarked(addr+1)) { | |
| 7408 // this is an allocated object that might not yet be initialized | |
| 7409 assert(_skip_bits == 0, "tautology"); | |
| 7410 _skip_bits = 2; // skip next two marked bits ("Printezis-marks") | |
| 7411 oop p = oop(addr); | |
|
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7412 if (p->klass_or_null() == NULL) { |
| 0 | 7413 // in the case of Clean-on-Enter optimization, redirty card |
| 7414 // and avoid clearing card by increasing the threshold. | |
|
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7415 return true; |
| 0 | 7416 } |
| 7417 } | |
| 7418 scan_oops_in_oop(addr); | |
|
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7419 return true; |
| 0 | 7420 } |
| 7421 | |
| 7422 void Par_MarkFromRootsClosure::scan_oops_in_oop(HeapWord* ptr) { | |
| 7423 assert(_bit_map->isMarked(ptr), "expected bit to be set"); | |
| 7424 // Should we assert that our work queue is empty or | |
| 7425 // below some drain limit? | |
| 7426 assert(_work_queue->size() == 0, | |
| 7427 "should drain stack to limit stack usage"); | |
| 7428 // convert ptr to an oop preparatory to scanning | |
|
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7429 oop obj = oop(ptr); |
| 0 | 7430 // Ignore mark word in verification below, since we |
| 7431 // may be running concurrent with mutators. | |
|
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7432 assert(obj->is_oop(true), "should be an oop"); |
| 0 | 7433 assert(_finger <= ptr, "_finger runneth ahead"); |
| 7434 // advance the finger to right end of this object | |
|
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7435 _finger = ptr + obj->size(); |
| 0 | 7436 assert(_finger > ptr, "we just incremented it above"); |
| 7437 // On large heaps, it may take us some time to get through | |
| 7438 // the marking phase (especially if running iCMS). During | |
| 7439 // this time it's possible that a lot of mutations have | |
| 7440 // accumulated in the card table and the mod union table -- | |
| 7441 // these mutation records are redundant until we have | |
| 7442 // actually traced into the corresponding card. | |
| 7443 // Here, we check whether advancing the finger would make | |
| 7444 // us cross into a new card, and if so clear corresponding | |
| 7445 // cards in the MUT (preclean them in the card-table in the | |
| 7446 // future). | |
| 7447 | |
| 7448 // The clean-on-enter optimization is disabled by default, | |
| 7449 // until we fix 6178663. | |
| 7450 if (CMSCleanOnEnter && (_finger > _threshold)) { | |
| 7451 // [_threshold, _finger) represents the interval | |
| 7452 // of cards to be cleared in MUT (or precleaned in card table). | |
| 7453 // The set of cards to be cleared is all those that overlap | |
| 7454 // with the interval [_threshold, _finger); note that | |
| 7455 // _threshold is always kept card-aligned but _finger isn't | |
| 7456 // always card-aligned. | |
| 7457 HeapWord* old_threshold = _threshold; | |
| 7458 assert(old_threshold == (HeapWord*)round_to( | |
| 7459 (intptr_t)old_threshold, CardTableModRefBS::card_size), | |
| 7460 "_threshold should always be card-aligned"); | |
| 7461 _threshold = (HeapWord*)round_to( | |
| 7462 (intptr_t)_finger, CardTableModRefBS::card_size); | |
| 7463 MemRegion mr(old_threshold, _threshold); | |
| 7464 assert(!mr.is_empty(), "Control point invariant"); | |
| 7465 assert(_span.contains(mr), "Should clear within span"); // _whole_span ?? | |
| 7466 _mut->clear_range(mr); | |
| 7467 } | |
| 7468 | |
| 7469 // Note: the local finger doesn't advance while we drain | |
| 7470 // the stack below, but the global finger sure can and will. | |
| 7471 HeapWord** gfa = _task->global_finger_addr(); | |
| 7472 Par_PushOrMarkClosure pushOrMarkClosure(_collector, | |
| 7473 _span, _bit_map, | |
| 7474 _work_queue, | |
| 7475 _overflow_stack, | |
| 7476 _finger, | |
| 7477 gfa, this); | |
|
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7478 bool res = _work_queue->push(obj); // overflow could occur here |
| 0 | 7479 assert(res, "Will hold once we use workqueues"); |
| 7480 while (true) { | |
| 7481 oop new_oop; | |
| 7482 if (!_work_queue->pop_local(new_oop)) { | |
| 7483 // We emptied our work_queue; check if there's stuff that can | |
| 7484 // be gotten from the overflow stack. | |
| 7485 if (CMSConcMarkingTask::get_work_from_overflow_stack( | |
| 7486 _overflow_stack, _work_queue)) { | |
| 7487 do_yield_check(); | |
| 7488 continue; | |
| 7489 } else { // done | |
| 7490 break; | |
| 7491 } | |
| 7492 } | |
| 7493 // Skip verifying header mark word below because we are | |
| 7494 // running concurrent with mutators. | |
| 7495 assert(new_oop->is_oop(true), "Oops! expected to pop an oop"); | |
| 7496 // now scan this oop's oops | |
| 7497 new_oop->oop_iterate(&pushOrMarkClosure); | |
| 7498 do_yield_check(); | |
| 7499 } | |
| 7500 assert(_work_queue->size() == 0, "tautology, emphasizing post-condition"); | |
| 7501 } | |
| 7502 | |
| 7503 // Yield in response to a request from VM Thread or | |
| 7504 // from mutators. | |
| 7505 void Par_MarkFromRootsClosure::do_yield_work() { | |
| 7506 assert(_task != NULL, "sanity"); | |
| 7507 _task->yield(); | |
| 7508 } | |
| 7509 | |
| 7510 // A variant of the above used for verifying CMS marking work. | |
| 7511 MarkFromRootsVerifyClosure::MarkFromRootsVerifyClosure(CMSCollector* collector, | |
| 7512 MemRegion span, | |
| 7513 CMSBitMap* verification_bm, CMSBitMap* cms_bm, | |
| 7514 CMSMarkStack* mark_stack): | |
| 7515 _collector(collector), | |
| 7516 _span(span), | |
| 7517 _verification_bm(verification_bm), | |
| 7518 _cms_bm(cms_bm), | |
| 7519 _mark_stack(mark_stack), | |
| 7520 _pam_verify_closure(collector, span, verification_bm, cms_bm, | |
| 7521 mark_stack) | |
| 7522 { | |
| 7523 assert(_mark_stack->isEmpty(), "stack should be empty"); | |
| 7524 _finger = _verification_bm->startWord(); | |
| 7525 assert(_collector->_restart_addr == NULL, "Sanity check"); | |
| 7526 assert(_span.contains(_finger), "Out of bounds _finger?"); | |
| 7527 } | |
| 7528 | |
| 7529 void MarkFromRootsVerifyClosure::reset(HeapWord* addr) { | |
| 7530 assert(_mark_stack->isEmpty(), "would cause duplicates on stack"); | |
| 7531 assert(_span.contains(addr), "Out of bounds _finger?"); | |
| 7532 _finger = addr; | |
| 7533 } | |
| 7534 | |
| 7535 // Should revisit to see if this should be restructured for | |
| 7536 // greater efficiency. | |
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7537 bool MarkFromRootsVerifyClosure::do_bit(size_t offset) { |
| 0 | 7538 // convert offset into a HeapWord* |
| 7539 HeapWord* addr = _verification_bm->startWord() + offset; | |
| 7540 assert(_verification_bm->endWord() && addr < _verification_bm->endWord(), | |
| 7541 "address out of range"); | |
| 7542 assert(_verification_bm->isMarked(addr), "tautology"); | |
| 7543 assert(_cms_bm->isMarked(addr), "tautology"); | |
| 7544 | |
| 7545 assert(_mark_stack->isEmpty(), | |
| 7546 "should drain stack to limit stack usage"); | |
| 7547 // convert addr to an oop preparatory to scanning | |
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7548 oop obj = oop(addr); |
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7549 assert(obj->is_oop(), "should be an oop"); |
| 0 | 7550 assert(_finger <= addr, "_finger runneth ahead"); |
| 7551 // advance the finger to right end of this object | |
|
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7552 _finger = addr + obj->size(); |
| 0 | 7553 assert(_finger > addr, "we just incremented it above"); |
| 7554 // Note: the finger doesn't advance while we drain | |
| 7555 // the stack below. | |
|
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7556 bool res = _mark_stack->push(obj); |
| 0 | 7557 assert(res, "Empty non-zero size stack should have space for single push"); |
| 7558 while (!_mark_stack->isEmpty()) { | |
| 7559 oop new_oop = _mark_stack->pop(); | |
| 7560 assert(new_oop->is_oop(), "Oops! expected to pop an oop"); | |
| 7561 // now scan this oop's oops | |
| 7562 new_oop->oop_iterate(&_pam_verify_closure); | |
| 7563 } | |
| 7564 assert(_mark_stack->isEmpty(), "tautology, emphasizing post-condition"); | |
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7565 return true; |
| 0 | 7566 } |
| 7567 | |
| 7568 PushAndMarkVerifyClosure::PushAndMarkVerifyClosure( | |
| 7569 CMSCollector* collector, MemRegion span, | |
| 7570 CMSBitMap* verification_bm, CMSBitMap* cms_bm, | |
| 7571 CMSMarkStack* mark_stack): | |
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7572 CMSOopClosure(collector->ref_processor()), |
| 0 | 7573 _collector(collector), |
| 7574 _span(span), | |
| 7575 _verification_bm(verification_bm), | |
| 7576 _cms_bm(cms_bm), | |
| 7577 _mark_stack(mark_stack) | |
| 7578 { } | |
| 7579 | |
|
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7580 void PushAndMarkVerifyClosure::do_oop(oop* p) { PushAndMarkVerifyClosure::do_oop_work(p); } |
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7581 void PushAndMarkVerifyClosure::do_oop(narrowOop* p) { PushAndMarkVerifyClosure::do_oop_work(p); } |
| 0 | 7582 |
| 7583 // Upon stack overflow, we discard (part of) the stack, | |
| 7584 // remembering the least address amongst those discarded | |
| 7585 // in CMSCollector's _restart_address. | |
| 7586 void PushAndMarkVerifyClosure::handle_stack_overflow(HeapWord* lost) { | |
| 7587 // Remember the least grey address discarded | |
| 7588 HeapWord* ra = (HeapWord*)_mark_stack->least_value(lost); | |
| 7589 _collector->lower_restart_addr(ra); | |
| 7590 _mark_stack->reset(); // discard stack contents | |
| 7591 _mark_stack->expand(); // expand the stack if possible | |
| 7592 } | |
| 7593 | |
|
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7594 void PushAndMarkVerifyClosure::do_oop(oop obj) { |
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7595 assert(obj->is_oop_or_null(), "expected an oop or NULL"); |
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7596 HeapWord* addr = (HeapWord*)obj; |
| 0 | 7597 if (_span.contains(addr) && !_verification_bm->isMarked(addr)) { |
| 7598 // Oop lies in _span and isn't yet grey or black | |
| 7599 _verification_bm->mark(addr); // now grey | |
| 7600 if (!_cms_bm->isMarked(addr)) { | |
| 7601 oop(addr)->print(); | |
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7602 gclog_or_tty->print_cr(" (" INTPTR_FORMAT " should have been marked)", |
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7603 addr); |
| 0 | 7604 fatal("... aborting"); |
| 7605 } | |
| 7606 | |
|
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7607 if (!_mark_stack->push(obj)) { // stack overflow |
| 0 | 7608 if (PrintCMSStatistics != 0) { |
| 7609 gclog_or_tty->print_cr("CMS marking stack overflow (benign) at " | |
| 7610 SIZE_FORMAT, _mark_stack->capacity()); | |
| 7611 } | |
| 7612 assert(_mark_stack->isFull(), "Else push should have succeeded"); | |
| 7613 handle_stack_overflow(addr); | |
| 7614 } | |
| 7615 // anything including and to the right of _finger | |
| 7616 // will be scanned as we iterate over the remainder of the | |
| 7617 // bit map | |
| 7618 } | |
| 7619 } | |
| 7620 | |
| 7621 PushOrMarkClosure::PushOrMarkClosure(CMSCollector* collector, | |
| 7622 MemRegion span, | |
| 7623 CMSBitMap* bitMap, CMSMarkStack* markStack, | |
| 7624 HeapWord* finger, MarkFromRootsClosure* parent) : | |
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7625 CMSOopClosure(collector->ref_processor()), |
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7626 _collector(collector), |
| 0 | 7627 _span(span), |
| 7628 _bitMap(bitMap), | |
| 7629 _markStack(markStack), | |
| 7630 _finger(finger), | |
| 935 | 7631 _parent(parent) |
| 0 | 7632 { } |
| 7633 | |
| 7634 Par_PushOrMarkClosure::Par_PushOrMarkClosure(CMSCollector* collector, | |
| 7635 MemRegion span, | |
| 7636 CMSBitMap* bit_map, | |
| 7637 OopTaskQueue* work_queue, | |
| 7638 CMSMarkStack* overflow_stack, | |
| 7639 HeapWord* finger, | |
| 7640 HeapWord** global_finger_addr, | |
| 7641 Par_MarkFromRootsClosure* parent) : | |
|
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7642 CMSOopClosure(collector->ref_processor()), |
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7643 _collector(collector), |
| 0 | 7644 _whole_span(collector->_span), |
| 7645 _span(span), | |
| 7646 _bit_map(bit_map), | |
| 7647 _work_queue(work_queue), | |
| 7648 _overflow_stack(overflow_stack), | |
| 7649 _finger(finger), | |
| 7650 _global_finger_addr(global_finger_addr), | |
| 935 | 7651 _parent(parent) |
| 0 | 7652 { } |
| 7653 | |
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7654 // Assumes thread-safe access by callers, who are |
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7655 // responsible for mutual exclusion. |
| 0 | 7656 void CMSCollector::lower_restart_addr(HeapWord* low) { |
| 7657 assert(_span.contains(low), "Out of bounds addr"); | |
| 7658 if (_restart_addr == NULL) { | |
| 7659 _restart_addr = low; | |
| 7660 } else { | |
| 7661 _restart_addr = MIN2(_restart_addr, low); | |
| 7662 } | |
| 7663 } | |
| 7664 | |
| 7665 // Upon stack overflow, we discard (part of) the stack, | |
| 7666 // remembering the least address amongst those discarded | |
| 7667 // in CMSCollector's _restart_address. | |
| 7668 void PushOrMarkClosure::handle_stack_overflow(HeapWord* lost) { | |
| 7669 // Remember the least grey address discarded | |
| 7670 HeapWord* ra = (HeapWord*)_markStack->least_value(lost); | |
| 7671 _collector->lower_restart_addr(ra); | |
| 7672 _markStack->reset(); // discard stack contents | |
| 7673 _markStack->expand(); // expand the stack if possible | |
| 7674 } | |
| 7675 | |
| 7676 // Upon stack overflow, we discard (part of) the stack, | |
| 7677 // remembering the least address amongst those discarded | |
| 7678 // in CMSCollector's _restart_address. | |
| 7679 void Par_PushOrMarkClosure::handle_stack_overflow(HeapWord* lost) { | |
| 7680 // We need to do this under a mutex to prevent other | |
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7681 // workers from interfering with the work done below. |
| 0 | 7682 MutexLockerEx ml(_overflow_stack->par_lock(), |
| 7683 Mutex::_no_safepoint_check_flag); | |
| 7684 // Remember the least grey address discarded | |
| 7685 HeapWord* ra = (HeapWord*)_overflow_stack->least_value(lost); | |
| 7686 _collector->lower_restart_addr(ra); | |
| 7687 _overflow_stack->reset(); // discard stack contents | |
| 7688 _overflow_stack->expand(); // expand the stack if possible | |
| 7689 } | |
| 7690 | |
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7691 void CMKlassClosure::do_klass(Klass* k) { |
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7692 assert(_oop_closure != NULL, "Not initialized?"); |
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7693 k->oops_do(_oop_closure); |
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7694 } |
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7695 |
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7696 void PushOrMarkClosure::do_oop(oop obj) { |
| 0 | 7697 // Ignore mark word because we are running concurrent with mutators. |
|
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7698 assert(obj->is_oop_or_null(true), "expected an oop or NULL"); |
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7699 HeapWord* addr = (HeapWord*)obj; |
| 0 | 7700 if (_span.contains(addr) && !_bitMap->isMarked(addr)) { |
| 7701 // Oop lies in _span and isn't yet grey or black | |
| 7702 _bitMap->mark(addr); // now grey | |
| 7703 if (addr < _finger) { | |
| 7704 // the bit map iteration has already either passed, or | |
| 7705 // sampled, this bit in the bit map; we'll need to | |
| 7706 // use the marking stack to scan this oop's oops. | |
| 7707 bool simulate_overflow = false; | |
| 7708 NOT_PRODUCT( | |
| 7709 if (CMSMarkStackOverflowALot && | |
| 7710 _collector->simulate_overflow()) { | |
| 7711 // simulate a stack overflow | |
| 7712 simulate_overflow = true; | |
| 7713 } | |
| 7714 ) | |
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7715 if (simulate_overflow || !_markStack->push(obj)) { // stack overflow |
| 0 | 7716 if (PrintCMSStatistics != 0) { |
| 7717 gclog_or_tty->print_cr("CMS marking stack overflow (benign) at " | |
| 7718 SIZE_FORMAT, _markStack->capacity()); | |
| 7719 } | |
| 7720 assert(simulate_overflow || _markStack->isFull(), "Else push should have succeeded"); | |
| 7721 handle_stack_overflow(addr); | |
| 7722 } | |
| 7723 } | |
| 7724 // anything including and to the right of _finger | |
| 7725 // will be scanned as we iterate over the remainder of the | |
| 7726 // bit map | |
| 7727 do_yield_check(); | |
| 7728 } | |
| 7729 } | |
| 7730 | |
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7731 void PushOrMarkClosure::do_oop(oop* p) { PushOrMarkClosure::do_oop_work(p); } |
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7732 void PushOrMarkClosure::do_oop(narrowOop* p) { PushOrMarkClosure::do_oop_work(p); } |
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7733 |
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7734 void Par_PushOrMarkClosure::do_oop(oop obj) { |
| 0 | 7735 // Ignore mark word because we are running concurrent with mutators. |
|
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7736 assert(obj->is_oop_or_null(true), "expected an oop or NULL"); |
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7737 HeapWord* addr = (HeapWord*)obj; |
| 0 | 7738 if (_whole_span.contains(addr) && !_bit_map->isMarked(addr)) { |
| 7739 // Oop lies in _span and isn't yet grey or black | |
| 7740 // We read the global_finger (volatile read) strictly after marking oop | |
| 7741 bool res = _bit_map->par_mark(addr); // now grey | |
| 7742 volatile HeapWord** gfa = (volatile HeapWord**)_global_finger_addr; | |
| 7743 // Should we push this marked oop on our stack? | |
| 7744 // -- if someone else marked it, nothing to do | |
| 7745 // -- if target oop is above global finger nothing to do | |
| 7746 // -- if target oop is in chunk and above local finger | |
| 7747 // then nothing to do | |
| 7748 // -- else push on work queue | |
| 7749 if ( !res // someone else marked it, they will deal with it | |
| 7750 || (addr >= *gfa) // will be scanned in a later task | |
| 7751 || (_span.contains(addr) && addr >= _finger)) { // later in this chunk | |
| 7752 return; | |
| 7753 } | |
| 7754 // the bit map iteration has already either passed, or | |
| 7755 // sampled, this bit in the bit map; we'll need to | |
| 7756 // use the marking stack to scan this oop's oops. | |
| 7757 bool simulate_overflow = false; | |
| 7758 NOT_PRODUCT( | |
| 7759 if (CMSMarkStackOverflowALot && | |
| 7760 _collector->simulate_overflow()) { | |
| 7761 // simulate a stack overflow | |
| 7762 simulate_overflow = true; | |
| 7763 } | |
| 7764 ) | |
| 7765 if (simulate_overflow || | |
|
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7766 !(_work_queue->push(obj) || _overflow_stack->par_push(obj))) { |
| 0 | 7767 // stack overflow |
| 7768 if (PrintCMSStatistics != 0) { | |
| 7769 gclog_or_tty->print_cr("CMS marking stack overflow (benign) at " | |
| 7770 SIZE_FORMAT, _overflow_stack->capacity()); | |
| 7771 } | |
| 7772 // We cannot assert that the overflow stack is full because | |
| 7773 // it may have been emptied since. | |
| 7774 assert(simulate_overflow || | |
| 7775 _work_queue->size() == _work_queue->max_elems(), | |
| 7776 "Else push should have succeeded"); | |
| 7777 handle_stack_overflow(addr); | |
| 7778 } | |
| 7779 do_yield_check(); | |
| 7780 } | |
| 7781 } | |
| 7782 | |
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7783 void Par_PushOrMarkClosure::do_oop(oop* p) { Par_PushOrMarkClosure::do_oop_work(p); } |
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7784 void Par_PushOrMarkClosure::do_oop(narrowOop* p) { Par_PushOrMarkClosure::do_oop_work(p); } |
| 0 | 7785 |
| 7786 PushAndMarkClosure::PushAndMarkClosure(CMSCollector* collector, | |
| 7787 MemRegion span, | |
| 7788 ReferenceProcessor* rp, | |
| 7789 CMSBitMap* bit_map, | |
| 7790 CMSBitMap* mod_union_table, | |
| 7791 CMSMarkStack* mark_stack, | |
| 7792 bool concurrent_precleaning): | |
|
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7793 CMSOopClosure(rp), |
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7794 _collector(collector), |
| 0 | 7795 _span(span), |
| 7796 _bit_map(bit_map), | |
| 7797 _mod_union_table(mod_union_table), | |
| 7798 _mark_stack(mark_stack), | |
| 935 | 7799 _concurrent_precleaning(concurrent_precleaning) |
| 0 | 7800 { |
| 7801 assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL"); | |
| 7802 } | |
| 7803 | |
| 7804 // Grey object rescan during pre-cleaning and second checkpoint phases -- | |
| 7805 // the non-parallel version (the parallel version appears further below.) | |
|
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7806 void PushAndMarkClosure::do_oop(oop obj) { |
|
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7807 // Ignore mark word verification. If during concurrent precleaning, |
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7808 // the object monitor may be locked. If during the checkpoint |
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7809 // phases, the object may already have been reached by a different |
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7810 // path and may be at the end of the global overflow list (so |
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7811 // the mark word may be NULL). |
|
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7812 assert(obj->is_oop_or_null(true /* ignore mark word */), |
| 0 | 7813 "expected an oop or NULL"); |
|
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7814 HeapWord* addr = (HeapWord*)obj; |
| 0 | 7815 // Check if oop points into the CMS generation |
| 7816 // and is not marked | |
| 7817 if (_span.contains(addr) && !_bit_map->isMarked(addr)) { | |
| 7818 // a white object ... | |
| 7819 _bit_map->mark(addr); // ... now grey | |
| 7820 // push on the marking stack (grey set) | |
| 7821 bool simulate_overflow = false; | |
| 7822 NOT_PRODUCT( | |
| 7823 if (CMSMarkStackOverflowALot && | |
| 7824 _collector->simulate_overflow()) { | |
| 7825 // simulate a stack overflow | |
| 7826 simulate_overflow = true; | |
| 7827 } | |
| 7828 ) | |
|
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7829 if (simulate_overflow || !_mark_stack->push(obj)) { |
| 0 | 7830 if (_concurrent_precleaning) { |
|
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7831 // During precleaning we can just dirty the appropriate card(s) |
| 0 | 7832 // in the mod union table, thus ensuring that the object remains |
|
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7833 // in the grey set and continue. In the case of object arrays |
|
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7834 // we need to dirty all of the cards that the object spans, |
|
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7835 // since the rescan of object arrays will be limited to the |
|
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7836 // dirty cards. |
|
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7837 // Note that no one can be intefering with us in this action |
|
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7838 // of dirtying the mod union table, so no locking or atomics |
|
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|
7839 // are required. |
|
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|
7840 if (obj->is_objArray()) { |
|
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7841 size_t sz = obj->size(); |
|
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|
7842 HeapWord* end_card_addr = (HeapWord*)round_to( |
|
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|
7843 (intptr_t)(addr+sz), CardTableModRefBS::card_size); |
|
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|
7844 MemRegion redirty_range = MemRegion(addr, end_card_addr); |
|
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|
7845 assert(!redirty_range.is_empty(), "Arithmetical tautology"); |
|
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7846 _mod_union_table->mark_range(redirty_range); |
|
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|
7847 } else { |
|
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|
7848 _mod_union_table->mark(addr); |
|
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|
7849 } |
| 0 | 7850 _collector->_ser_pmc_preclean_ovflw++; |
| 7851 } else { | |
| 7852 // During the remark phase, we need to remember this oop | |
| 7853 // in the overflow list. | |
|
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7854 _collector->push_on_overflow_list(obj); |
| 0 | 7855 _collector->_ser_pmc_remark_ovflw++; |
| 7856 } | |
| 7857 } | |
| 7858 } | |
| 7859 } | |
| 7860 | |
| 7861 Par_PushAndMarkClosure::Par_PushAndMarkClosure(CMSCollector* collector, | |
| 7862 MemRegion span, | |
| 7863 ReferenceProcessor* rp, | |
| 7864 CMSBitMap* bit_map, | |
|
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7865 OopTaskQueue* work_queue): |
|
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7866 CMSOopClosure(rp), |
|
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7867 _collector(collector), |
| 0 | 7868 _span(span), |
| 7869 _bit_map(bit_map), | |
| 935 | 7870 _work_queue(work_queue) |
| 0 | 7871 { |
| 7872 assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL"); | |
| 7873 } | |
| 7874 | |
|
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7875 void PushAndMarkClosure::do_oop(oop* p) { PushAndMarkClosure::do_oop_work(p); } |
|
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7876 void PushAndMarkClosure::do_oop(narrowOop* p) { PushAndMarkClosure::do_oop_work(p); } |
|
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7877 |
| 0 | 7878 // Grey object rescan during second checkpoint phase -- |
| 7879 // the parallel version. | |
|
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7880 void Par_PushAndMarkClosure::do_oop(oop obj) { |
| 0 | 7881 // In the assert below, we ignore the mark word because |
| 7882 // this oop may point to an already visited object that is | |
| 7883 // on the overflow stack (in which case the mark word has | |
| 7884 // been hijacked for chaining into the overflow stack -- | |
| 7885 // if this is the last object in the overflow stack then | |
| 7886 // its mark word will be NULL). Because this object may | |
| 7887 // have been subsequently popped off the global overflow | |
| 7888 // stack, and the mark word possibly restored to the prototypical | |
| 7889 // value, by the time we get to examined this failing assert in | |
| 7890 // the debugger, is_oop_or_null(false) may subsequently start | |
| 7891 // to hold. | |
|
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7892 assert(obj->is_oop_or_null(true), |
| 0 | 7893 "expected an oop or NULL"); |
|
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7894 HeapWord* addr = (HeapWord*)obj; |
| 0 | 7895 // Check if oop points into the CMS generation |
| 7896 // and is not marked | |
| 7897 if (_span.contains(addr) && !_bit_map->isMarked(addr)) { | |
| 7898 // a white object ... | |
| 7899 // If we manage to "claim" the object, by being the | |
| 7900 // first thread to mark it, then we push it on our | |
| 7901 // marking stack | |
| 7902 if (_bit_map->par_mark(addr)) { // ... now grey | |
| 7903 // push on work queue (grey set) | |
| 7904 bool simulate_overflow = false; | |
| 7905 NOT_PRODUCT( | |
| 7906 if (CMSMarkStackOverflowALot && | |
| 7907 _collector->par_simulate_overflow()) { | |
| 7908 // simulate a stack overflow | |
| 7909 simulate_overflow = true; | |
| 7910 } | |
| 7911 ) | |
|
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7912 if (simulate_overflow || !_work_queue->push(obj)) { |
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7913 _collector->par_push_on_overflow_list(obj); |
| 0 | 7914 _collector->_par_pmc_remark_ovflw++; // imprecise OK: no need to CAS |
| 7915 } | |
| 7916 } // Else, some other thread got there first | |
| 7917 } | |
| 7918 } | |
| 7919 | |
|
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7920 void Par_PushAndMarkClosure::do_oop(oop* p) { Par_PushAndMarkClosure::do_oop_work(p); } |
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7921 void Par_PushAndMarkClosure::do_oop(narrowOop* p) { Par_PushAndMarkClosure::do_oop_work(p); } |
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7922 |
| 0 | 7923 void CMSPrecleanRefsYieldClosure::do_yield_work() { |
| 7924 Mutex* bml = _collector->bitMapLock(); | |
| 7925 assert_lock_strong(bml); | |
| 7926 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 7927 "CMS thread should hold CMS token"); | |
| 7928 | |
| 7929 bml->unlock(); | |
| 7930 ConcurrentMarkSweepThread::desynchronize(true); | |
| 7931 | |
| 7932 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7933 | |
| 7934 _collector->stopTimer(); | |
| 7935 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 7936 if (PrintCMSStatistics != 0) { | |
| 7937 _collector->incrementYields(); | |
| 7938 } | |
| 7939 _collector->icms_wait(); | |
| 7940 | |
| 7941 // See the comment in coordinator_yield() | |
| 7942 for (unsigned i = 0; i < CMSYieldSleepCount && | |
| 7943 ConcurrentMarkSweepThread::should_yield() && | |
| 7944 !CMSCollector::foregroundGCIsActive(); ++i) { | |
| 7945 os::sleep(Thread::current(), 1, false); | |
| 7946 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7947 } | |
| 7948 | |
| 7949 ConcurrentMarkSweepThread::synchronize(true); | |
| 7950 bml->lock(); | |
| 7951 | |
| 7952 _collector->startTimer(); | |
| 7953 } | |
| 7954 | |
| 7955 bool CMSPrecleanRefsYieldClosure::should_return() { | |
| 7956 if (ConcurrentMarkSweepThread::should_yield()) { | |
| 7957 do_yield_work(); | |
| 7958 } | |
| 7959 return _collector->foregroundGCIsActive(); | |
| 7960 } | |
| 7961 | |
| 7962 void MarkFromDirtyCardsClosure::do_MemRegion(MemRegion mr) { | |
| 7963 assert(((size_t)mr.start())%CardTableModRefBS::card_size_in_words == 0, | |
| 7964 "mr should be aligned to start at a card boundary"); | |
| 7965 // We'd like to assert: | |
| 7966 // assert(mr.word_size()%CardTableModRefBS::card_size_in_words == 0, | |
| 7967 // "mr should be a range of cards"); | |
| 7968 // However, that would be too strong in one case -- the last | |
| 7969 // partition ends at _unallocated_block which, in general, can be | |
| 7970 // an arbitrary boundary, not necessarily card aligned. | |
| 7971 if (PrintCMSStatistics != 0) { | |
| 7972 _num_dirty_cards += | |
| 7973 mr.word_size()/CardTableModRefBS::card_size_in_words; | |
| 7974 } | |
| 7975 _space->object_iterate_mem(mr, &_scan_cl); | |
| 7976 } | |
| 7977 | |
| 7978 SweepClosure::SweepClosure(CMSCollector* collector, | |
| 7979 ConcurrentMarkSweepGeneration* g, | |
| 7980 CMSBitMap* bitMap, bool should_yield) : | |
| 7981 _collector(collector), | |
| 7982 _g(g), | |
| 7983 _sp(g->cmsSpace()), | |
| 7984 _limit(_sp->sweep_limit()), | |
| 7985 _freelistLock(_sp->freelistLock()), | |
| 7986 _bitMap(bitMap), | |
| 7987 _yield(should_yield), | |
| 7988 _inFreeRange(false), // No free range at beginning of sweep | |
| 7989 _freeRangeInFreeLists(false), // No free range at beginning of sweep | |
| 7990 _lastFreeRangeCoalesced(false), | |
| 7991 _freeFinger(g->used_region().start()) | |
| 7992 { | |
| 7993 NOT_PRODUCT( | |
| 7994 _numObjectsFreed = 0; | |
| 7995 _numWordsFreed = 0; | |
| 7996 _numObjectsLive = 0; | |
| 7997 _numWordsLive = 0; | |
| 7998 _numObjectsAlreadyFree = 0; | |
| 7999 _numWordsAlreadyFree = 0; | |
| 8000 _last_fc = NULL; | |
| 8001 | |
| 8002 _sp->initializeIndexedFreeListArrayReturnedBytes(); | |
|
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|
8003 _sp->dictionary()->initialize_dict_returned_bytes(); |
| 0 | 8004 ) |
| 8005 assert(_limit >= _sp->bottom() && _limit <= _sp->end(), | |
| 8006 "sweep _limit out of bounds"); | |
| 8007 if (CMSTraceSweeper) { | |
|
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|
8008 gclog_or_tty->print_cr("\n====================\nStarting new sweep with limit " PTR_FORMAT, |
|
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|
8009 _limit); |
|
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|
8010 } |
|
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|
8011 } |
|
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|
8012 |
|
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|
8013 void SweepClosure::print_on(outputStream* st) const { |
|
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|
8014 tty->print_cr("_sp = [" PTR_FORMAT "," PTR_FORMAT ")", |
|
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|
8015 _sp->bottom(), _sp->end()); |
|
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|
8016 tty->print_cr("_limit = " PTR_FORMAT, _limit); |
|
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|
8017 tty->print_cr("_freeFinger = " PTR_FORMAT, _freeFinger); |
|
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|
8018 NOT_PRODUCT(tty->print_cr("_last_fc = " PTR_FORMAT, _last_fc);) |
|
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|
8019 tty->print_cr("_inFreeRange = %d, _freeRangeInFreeLists = %d, _lastFreeRangeCoalesced = %d", |
|
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|
8020 _inFreeRange, _freeRangeInFreeLists, _lastFreeRangeCoalesced); |
|
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|
8021 } |
|
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|
8022 |
|
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|
8023 #ifndef PRODUCT |
|
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|
8024 // Assertion checking only: no useful work in product mode -- |
|
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|
8025 // however, if any of the flags below become product flags, |
|
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|
8026 // you may need to review this code to see if it needs to be |
|
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|
8027 // enabled in product mode. |
| 0 | 8028 SweepClosure::~SweepClosure() { |
| 8029 assert_lock_strong(_freelistLock); | |
|
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|
8030 assert(_limit >= _sp->bottom() && _limit <= _sp->end(), |
|
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|
8031 "sweep _limit out of bounds"); |
| 0 | 8032 if (inFreeRange()) { |
|
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|
8033 warning("inFreeRange() should have been reset; dumping state of SweepClosure"); |
|
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|
8034 print(); |
|
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|
8035 ShouldNotReachHere(); |
|
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|
8036 } |
|
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|
8037 if (Verbose && PrintGC) { |
|
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|
8038 gclog_or_tty->print("Collected "SIZE_FORMAT" objects, " SIZE_FORMAT " bytes", |
|
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|
8039 _numObjectsFreed, _numWordsFreed*sizeof(HeapWord)); |
|
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|
8040 gclog_or_tty->print_cr("\nLive "SIZE_FORMAT" objects, " |
|
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|
8041 SIZE_FORMAT" bytes " |
|
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|
8042 "Already free "SIZE_FORMAT" objects, "SIZE_FORMAT" bytes", |
|
537a4053b0f9
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|
8043 _numObjectsLive, _numWordsLive*sizeof(HeapWord), |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8044 _numObjectsAlreadyFree, _numWordsAlreadyFree*sizeof(HeapWord)); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8045 size_t totalBytes = (_numWordsFreed + _numWordsLive + _numWordsAlreadyFree) |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8046 * sizeof(HeapWord); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8047 gclog_or_tty->print_cr("Total sweep: "SIZE_FORMAT" bytes", totalBytes); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8048 |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8049 if (PrintCMSStatistics && CMSVerifyReturnedBytes) { |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8050 size_t indexListReturnedBytes = _sp->sumIndexedFreeListArrayReturnedBytes(); |
|
6028
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jmasa
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|
8051 size_t dict_returned_bytes = _sp->dictionary()->sum_dict_returned_bytes(); |
|
f69a5d43dc19
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jmasa
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|
8052 size_t returned_bytes = indexListReturnedBytes + dict_returned_bytes; |
|
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
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|
8053 gclog_or_tty->print("Returned "SIZE_FORMAT" bytes", returned_bytes); |
|
3746
537a4053b0f9
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|
8054 gclog_or_tty->print(" Indexed List Returned "SIZE_FORMAT" bytes", |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8055 indexListReturnedBytes); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8056 gclog_or_tty->print_cr(" Dictionary Returned "SIZE_FORMAT" bytes", |
|
6028
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jmasa
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|
8057 dict_returned_bytes); |
|
3746
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|
8058 } |
|
537a4053b0f9
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|
8059 } |
| 0 | 8060 if (CMSTraceSweeper) { |
|
3746
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|
8061 gclog_or_tty->print_cr("end of sweep with _limit = " PTR_FORMAT "\n================", |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8062 _limit); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8063 } |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8064 } |
|
537a4053b0f9
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|
8065 #endif // PRODUCT |
| 0 | 8066 |
| 8067 void SweepClosure::initialize_free_range(HeapWord* freeFinger, | |
| 8068 bool freeRangeInFreeLists) { | |
| 8069 if (CMSTraceSweeper) { | |
|
2132
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7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
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|
8070 gclog_or_tty->print("---- Start free range at 0x%x with free block (%d)\n", |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
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changeset
|
8071 freeFinger, freeRangeInFreeLists); |
| 0 | 8072 } |
| 8073 assert(!inFreeRange(), "Trampling existing free range"); | |
| 8074 set_inFreeRange(true); | |
| 8075 set_lastFreeRangeCoalesced(false); | |
| 8076 | |
| 8077 set_freeFinger(freeFinger); | |
| 8078 set_freeRangeInFreeLists(freeRangeInFreeLists); | |
| 8079 if (CMSTestInFreeList) { | |
| 8080 if (freeRangeInFreeLists) { | |
| 8081 FreeChunk* fc = (FreeChunk*) freeFinger; | |
|
6028
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7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
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|
8082 assert(fc->is_free(), "A chunk on the free list should be free."); |
| 0 | 8083 assert(fc->size() > 0, "Free range should have a size"); |
|
6028
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jmasa
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|
8084 assert(_sp->verify_chunk_in_free_list(fc), "Chunk is not in free lists"); |
| 0 | 8085 } |
| 8086 } | |
| 8087 } | |
| 8088 | |
| 8089 // Note that the sweeper runs concurrently with mutators. Thus, | |
| 8090 // it is possible for direct allocation in this generation to happen | |
| 8091 // in the middle of the sweep. Note that the sweeper also coalesces | |
| 8092 // contiguous free blocks. Thus, unless the sweeper and the allocator | |
| 8093 // synchronize appropriately freshly allocated blocks may get swept up. | |
| 8094 // This is accomplished by the sweeper locking the free lists while | |
| 8095 // it is sweeping. Thus blocks that are determined to be free are | |
| 8096 // indeed free. There is however one additional complication: | |
| 8097 // blocks that have been allocated since the final checkpoint and | |
| 8098 // mark, will not have been marked and so would be treated as | |
| 8099 // unreachable and swept up. To prevent this, the allocator marks | |
| 8100 // the bit map when allocating during the sweep phase. This leads, | |
| 8101 // however, to a further complication -- objects may have been allocated | |
| 8102 // but not yet initialized -- in the sense that the header isn't yet | |
| 8103 // installed. The sweeper can not then determine the size of the block | |
| 8104 // in order to skip over it. To deal with this case, we use a technique | |
| 8105 // (due to Printezis) to encode such uninitialized block sizes in the | |
| 8106 // bit map. Since the bit map uses a bit per every HeapWord, but the | |
| 8107 // CMS generation has a minimum object size of 3 HeapWords, it follows | |
| 8108 // that "normal marks" won't be adjacent in the bit map (there will | |
| 8109 // always be at least two 0 bits between successive 1 bits). We make use | |
| 8110 // of these "unused" bits to represent uninitialized blocks -- the bit | |
| 8111 // corresponding to the start of the uninitialized object and the next | |
| 8112 // bit are both set. Finally, a 1 bit marks the end of the object that | |
| 8113 // started with the two consecutive 1 bits to indicate its potentially | |
| 8114 // uninitialized state. | |
| 8115 | |
| 8116 size_t SweepClosure::do_blk_careful(HeapWord* addr) { | |
| 8117 FreeChunk* fc = (FreeChunk*)addr; | |
| 8118 size_t res; | |
| 8119 | |
|
1720
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
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1716
diff
changeset
|
8120 // 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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1716
diff
changeset
|
8121 // 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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1716
diff
changeset
|
8122 // we started the sweep, it may no longer be one because heap expansion |
|
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
parents:
1716
diff
changeset
|
8123 // may have caused us to coalesce the block ending at the address _limit |
|
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
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1716
diff
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|
8124 // with a newly expanded chunk (this happens when _limit was set to the |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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changeset
|
8125 // previous _end of the space), so we may have stepped past _limit: |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8126 // see the following Zeno-like trail of CRs 6977970, 7008136, 7042740. |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
changeset
|
8127 if (addr >= _limit) { // we have swept up to or past the limit: finish up |
| 0 | 8128 assert(_limit >= _sp->bottom() && _limit <= _sp->end(), |
| 8129 "sweep _limit out of bounds"); | |
|
1720
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
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1716
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|
8130 assert(addr < _sp->end(), "addr out of bounds"); |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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3356
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|
8131 // Flush any free range we might be holding as a single |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
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|
8132 // coalesced chunk to the appropriate free list. |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
changeset
|
8133 if (inFreeRange()) { |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
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|
8134 assert(freeFinger() >= _sp->bottom() && freeFinger() < _limit, |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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|
8135 err_msg("freeFinger() " PTR_FORMAT" is out-of-bounds", freeFinger())); |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
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|
8136 flush_cur_free_chunk(freeFinger(), |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
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|
8137 pointer_delta(addr, freeFinger())); |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
changeset
|
8138 if (CMSTraceSweeper) { |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
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|
8139 gclog_or_tty->print("Sweep: last chunk: "); |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8140 gclog_or_tty->print("put_free_blk 0x%x ("SIZE_FORMAT") " |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
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|
8141 "[coalesced:"SIZE_FORMAT"]\n", |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8142 freeFinger(), pointer_delta(addr, freeFinger()), |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
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|
8143 lastFreeRangeCoalesced()); |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8144 } |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8145 } |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8146 |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8147 // help the iterator loop finish |
|
1720
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
parents:
1716
diff
changeset
|
8148 return pointer_delta(_sp->end(), addr); |
|
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
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1716
diff
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|
8149 } |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
changeset
|
8150 |
|
1720
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
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1716
diff
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|
8151 assert(addr < _limit, "sweep invariant"); |
| 0 | 8152 // check if we should yield |
| 8153 do_yield_check(addr); | |
|
6028
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jmasa
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6026
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|
8154 if (fc->is_free()) { |
| 0 | 8155 // Chunk that is already free |
| 8156 res = fc->size(); | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8157 do_already_free_chunk(fc); |
| 0 | 8158 debug_only(_sp->verifyFreeLists()); |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
diff
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|
8159 // If we flush the chunk at hand in lookahead_and_flush() |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
diff
changeset
|
8160 // and it's coalesced with a preceding chunk, then the |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
diff
changeset
|
8161 // process of "mangling" the payload of the coalesced block |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
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|
8162 // will cause erasure of the size information from the |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
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|
8163 // (erstwhile) header of all the coalesced blocks but the |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
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|
8164 // first, so the first disjunct in the assert will not hold |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
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|
8165 // in that specific case (in which case the second disjunct |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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3356
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|
8166 // will hold). |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
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|
8167 assert(res == fc->size() || ((HeapWord*)fc) + res >= _limit, |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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3356
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|
8168 "Otherwise the size info doesn't change at this step"); |
| 0 | 8169 NOT_PRODUCT( |
| 8170 _numObjectsAlreadyFree++; | |
| 8171 _numWordsAlreadyFree += res; | |
| 8172 ) | |
| 8173 NOT_PRODUCT(_last_fc = fc;) | |
| 8174 } else if (!_bitMap->isMarked(addr)) { | |
| 8175 // Chunk is fresh garbage | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
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|
8176 res = do_garbage_chunk(fc); |
| 0 | 8177 debug_only(_sp->verifyFreeLists()); |
| 8178 NOT_PRODUCT( | |
| 8179 _numObjectsFreed++; | |
| 8180 _numWordsFreed += res; | |
| 8181 ) | |
| 8182 } else { | |
| 8183 // Chunk that is alive. | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
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|
8184 res = do_live_chunk(fc); |
| 0 | 8185 debug_only(_sp->verifyFreeLists()); |
| 8186 NOT_PRODUCT( | |
| 8187 _numObjectsLive++; | |
| 8188 _numWordsLive += res; | |
| 8189 ) | |
| 8190 } | |
| 8191 return res; | |
| 8192 } | |
| 8193 | |
| 8194 // For the smart allocation, record following | |
| 8195 // split deaths - a free chunk is removed from its free list because | |
| 8196 // it is being split into two or more chunks. | |
| 8197 // split birth - a free chunk is being added to its free list because | |
| 8198 // a larger free chunk has been split and resulted in this free chunk. | |
| 8199 // coal death - a free chunk is being removed from its free list because | |
| 8200 // it is being coalesced into a large free chunk. | |
| 8201 // coal birth - a free chunk is being added to its free list because | |
| 8202 // it was created when two or more free chunks where coalesced into | |
| 8203 // this free chunk. | |
| 8204 // | |
| 8205 // These statistics are used to determine the desired number of free | |
| 8206 // chunks of a given size. The desired number is chosen to be relative | |
| 8207 // to the end of a CMS sweep. The desired number at the end of a sweep | |
| 8208 // is the | |
| 8209 // count-at-end-of-previous-sweep (an amount that was enough) | |
| 8210 // - count-at-beginning-of-current-sweep (the excess) | |
| 8211 // + split-births (gains in this size during interval) | |
| 8212 // - split-deaths (demands on this size during interval) | |
| 8213 // where the interval is from the end of one sweep to the end of the | |
| 8214 // next. | |
| 8215 // | |
| 8216 // When sweeping the sweeper maintains an accumulated chunk which is | |
| 8217 // the chunk that is made up of chunks that have been coalesced. That | |
| 8218 // will be termed the left-hand chunk. A new chunk of garbage that | |
| 8219 // is being considered for coalescing will be referred to as the | |
| 8220 // right-hand chunk. | |
| 8221 // | |
| 8222 // When making a decision on whether to coalesce a right-hand chunk with | |
| 8223 // the current left-hand chunk, the current count vs. the desired count | |
| 8224 // of the left-hand chunk is considered. Also if the right-hand chunk | |
| 8225 // is near the large chunk at the end of the heap (see | |
| 8226 // ConcurrentMarkSweepGeneration::isNearLargestChunk()), then the | |
| 8227 // left-hand chunk is coalesced. | |
| 8228 // | |
| 8229 // When making a decision about whether to split a chunk, the desired count | |
| 8230 // vs. the current count of the candidate to be split is also considered. | |
| 8231 // If the candidate is underpopulated (currently fewer chunks than desired) | |
| 8232 // a chunk of an overpopulated (currently more chunks than desired) size may | |
| 8233 // be chosen. The "hint" associated with a free list, if non-null, points | |
| 8234 // to a free list which may be overpopulated. | |
| 8235 // | |
| 8236 | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
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|
8237 void SweepClosure::do_already_free_chunk(FreeChunk* fc) { |
|
3746
537a4053b0f9
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ysr
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3356
diff
changeset
|
8238 const size_t size = fc->size(); |
| 0 | 8239 // Chunks that cannot be coalesced are not in the |
| 8240 // free lists. | |
| 8241 if (CMSTestInFreeList && !fc->cantCoalesce()) { | |
|
6028
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6026
diff
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|
8242 assert(_sp->verify_chunk_in_free_list(fc), |
| 0 | 8243 "free chunk should be in free lists"); |
| 8244 } | |
| 8245 // a chunk that is already free, should not have been | |
| 8246 // marked in the bit map | |
|
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|
8247 HeapWord* const addr = (HeapWord*) fc; |
| 0 | 8248 assert(!_bitMap->isMarked(addr), "free chunk should be unmarked"); |
| 8249 // Verify that the bit map has no bits marked between | |
| 8250 // addr and purported end of this block. | |
| 8251 _bitMap->verifyNoOneBitsInRange(addr + 1, addr + size); | |
| 8252 | |
|
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|
8253 // Some chunks cannot be coalesced under any circumstances. |
| 0 | 8254 // See the definition of cantCoalesce(). |
| 8255 if (!fc->cantCoalesce()) { | |
| 8256 // This chunk can potentially be coalesced. | |
| 8257 if (_sp->adaptive_freelists()) { | |
| 8258 // All the work is done in | |
|
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|
8259 do_post_free_or_garbage_chunk(fc, size); |
| 0 | 8260 } else { // Not adaptive free lists |
| 8261 // this is a free chunk that can potentially be coalesced by the sweeper; | |
| 8262 if (!inFreeRange()) { | |
| 8263 // if the next chunk is a free block that can't be coalesced | |
| 8264 // it doesn't make sense to remove this chunk from the free lists | |
| 8265 FreeChunk* nextChunk = (FreeChunk*)(addr + size); | |
|
2136
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changeset
|
8266 assert((HeapWord*)nextChunk <= _sp->end(), "Chunk size out of bounds?"); |
|
c91cc404ca46
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|
8267 if ((HeapWord*)nextChunk < _sp->end() && // There is another free chunk to the right ... |
|
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|
8268 nextChunk->is_free() && // ... which is free... |
|
2136
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|
8269 nextChunk->cantCoalesce()) { // ... but can't be coalesced |
| 0 | 8270 // nothing to do |
| 8271 } else { | |
| 8272 // Potentially the start of a new free range: | |
| 8273 // Don't eagerly remove it from the free lists. | |
| 8274 // No need to remove it if it will just be put | |
| 8275 // back again. (Also from a pragmatic point of view | |
| 8276 // if it is a free block in a region that is beyond | |
| 8277 // any allocated blocks, an assertion will fail) | |
| 8278 // Remember the start of a free run. | |
| 8279 initialize_free_range(addr, true); | |
| 8280 // end - can coalesce with next chunk | |
| 8281 } | |
| 8282 } else { | |
| 8283 // the midst of a free range, we are coalescing | |
|
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|
8284 print_free_block_coalesced(fc); |
| 0 | 8285 if (CMSTraceSweeper) { |
| 8286 gclog_or_tty->print(" -- pick up free block 0x%x (%d)\n", fc, size); | |
| 8287 } | |
| 8288 // remove it from the free lists | |
| 8289 _sp->removeFreeChunkFromFreeLists(fc); | |
| 8290 set_lastFreeRangeCoalesced(true); | |
| 8291 // If the chunk is being coalesced and the current free range is | |
| 8292 // in the free lists, remove the current free range so that it | |
| 8293 // will be returned to the free lists in its entirety - all | |
| 8294 // the coalesced pieces included. | |
| 8295 if (freeRangeInFreeLists()) { | |
| 8296 FreeChunk* ffc = (FreeChunk*) freeFinger(); | |
| 8297 assert(ffc->size() == pointer_delta(addr, freeFinger()), | |
| 8298 "Size of free range is inconsistent with chunk size."); | |
| 8299 if (CMSTestInFreeList) { | |
|
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|
8300 assert(_sp->verify_chunk_in_free_list(ffc), |
| 0 | 8301 "free range is not in free lists"); |
| 8302 } | |
| 8303 _sp->removeFreeChunkFromFreeLists(ffc); | |
| 8304 set_freeRangeInFreeLists(false); | |
| 8305 } | |
| 8306 } | |
| 8307 } | |
|
3746
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changeset
|
8308 // Note that if the chunk is not coalescable (the else arm |
|
537a4053b0f9
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|
8309 // below), we unconditionally flush, without needing to do |
|
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|
8310 // a "lookahead," as we do below. |
|
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changeset
|
8311 if (inFreeRange()) lookahead_and_flush(fc, size); |
| 0 | 8312 } else { |
| 8313 // Code path common to both original and adaptive free lists. | |
| 8314 | |
| 8315 // cant coalesce with previous block; this should be treated | |
| 8316 // as the end of a free run if any | |
| 8317 if (inFreeRange()) { | |
| 8318 // we kicked some butt; time to pick up the garbage | |
|
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diff
changeset
|
8319 assert(freeFinger() < addr, "freeFinger points too high"); |
|
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1994
diff
changeset
|
8320 flush_cur_free_chunk(freeFinger(), pointer_delta(addr, freeFinger())); |
| 0 | 8321 } |
| 8322 // else, nothing to do, just continue | |
| 8323 } | |
| 8324 } | |
| 8325 | |
|
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|
8326 size_t SweepClosure::do_garbage_chunk(FreeChunk* fc) { |
| 0 | 8327 // This is a chunk of garbage. It is not in any free list. |
| 8328 // Add it to a free list or let it possibly be coalesced into | |
| 8329 // a larger chunk. | |
|
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changeset
|
8330 HeapWord* const addr = (HeapWord*) fc; |
|
537a4053b0f9
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|
8331 const size_t size = CompactibleFreeListSpace::adjustObjectSize(oop(addr)->size()); |
| 0 | 8332 |
| 8333 if (_sp->adaptive_freelists()) { | |
| 8334 // Verify that the bit map has no bits marked between | |
| 8335 // addr and purported end of just dead object. | |
| 8336 _bitMap->verifyNoOneBitsInRange(addr + 1, addr + size); | |
| 8337 | |
|
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diff
changeset
|
8338 do_post_free_or_garbage_chunk(fc, size); |
| 0 | 8339 } else { |
| 8340 if (!inFreeRange()) { | |
| 8341 // start of a new free range | |
| 8342 assert(size > 0, "A free range should have a size"); | |
| 8343 initialize_free_range(addr, false); | |
| 8344 } else { | |
| 8345 // this will be swept up when we hit the end of the | |
| 8346 // free range | |
| 8347 if (CMSTraceSweeper) { | |
| 8348 gclog_or_tty->print(" -- pick up garbage 0x%x (%d) \n", fc, size); | |
| 8349 } | |
| 8350 // If the chunk is being coalesced and the current free range is | |
| 8351 // in the free lists, remove the current free range so that it | |
| 8352 // will be returned to the free lists in its entirety - all | |
| 8353 // the coalesced pieces included. | |
| 8354 if (freeRangeInFreeLists()) { | |
| 8355 FreeChunk* ffc = (FreeChunk*)freeFinger(); | |
| 8356 assert(ffc->size() == pointer_delta(addr, freeFinger()), | |
| 8357 "Size of free range is inconsistent with chunk size."); | |
| 8358 if (CMSTestInFreeList) { | |
|
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6026
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|
8359 assert(_sp->verify_chunk_in_free_list(ffc), |
| 0 | 8360 "free range is not in free lists"); |
| 8361 } | |
| 8362 _sp->removeFreeChunkFromFreeLists(ffc); | |
| 8363 set_freeRangeInFreeLists(false); | |
| 8364 } | |
| 8365 set_lastFreeRangeCoalesced(true); | |
| 8366 } | |
| 8367 // this will be swept up when we hit the end of the free range | |
| 8368 | |
| 8369 // Verify that the bit map has no bits marked between | |
| 8370 // addr and purported end of just dead object. | |
| 8371 _bitMap->verifyNoOneBitsInRange(addr + 1, addr + size); | |
| 8372 } | |
|
3746
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changeset
|
8373 assert(_limit >= addr + size, |
|
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|
8374 "A freshly garbage chunk can't possibly straddle over _limit"); |
|
537a4053b0f9
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changeset
|
8375 if (inFreeRange()) lookahead_and_flush(fc, size); |
| 0 | 8376 return size; |
| 8377 } | |
| 8378 | |
|
2132
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diff
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|
8379 size_t SweepClosure::do_live_chunk(FreeChunk* fc) { |
| 0 | 8380 HeapWord* addr = (HeapWord*) fc; |
| 8381 // The sweeper has just found a live object. Return any accumulated | |
| 8382 // left hand chunk to the free lists. | |
| 8383 if (inFreeRange()) { | |
|
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diff
changeset
|
8384 assert(freeFinger() < addr, "freeFinger points too high"); |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
changeset
|
8385 flush_cur_free_chunk(freeFinger(), pointer_delta(addr, freeFinger())); |
|
4947ee68d19c
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1994
diff
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|
8386 } |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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diff
changeset
|
8387 |
|
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diff
changeset
|
8388 // This object is live: we'd normally expect this to be |
| 0 | 8389 // an oop, and like to assert the following: |
| 8390 // assert(oop(addr)->is_oop(), "live block should be an oop"); | |
| 8391 // However, as we commented above, this may be an object whose | |
| 8392 // header hasn't yet been initialized. | |
| 8393 size_t size; | |
| 8394 assert(_bitMap->isMarked(addr), "Tautology for this control point"); | |
| 8395 if (_bitMap->isMarked(addr + 1)) { | |
| 8396 // Determine the size from the bit map, rather than trying to | |
| 8397 // compute it from the object header. | |
| 8398 HeapWord* nextOneAddr = _bitMap->getNextMarkedWordAddress(addr + 2); | |
| 8399 size = pointer_delta(nextOneAddr + 1, addr); | |
| 8400 assert(size == CompactibleFreeListSpace::adjustObjectSize(size), | |
| 8401 "alignment problem"); | |
| 8402 | |
| 9152 | 8403 #ifdef ASSERT |
|
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6197
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|
8404 if (oop(addr)->klass_or_null() != NULL) { |
| 0 | 8405 // Ignore mark word because we are running concurrent with mutators |
| 8406 assert(oop(addr)->is_oop(true), "live block should be an oop"); | |
| 8407 assert(size == | |
| 8408 CompactibleFreeListSpace::adjustObjectSize(oop(addr)->size()), | |
| 8409 "P-mark and computed size do not agree"); | |
| 8410 } | |
|
2132
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diff
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|
8411 #endif |
| 0 | 8412 |
| 8413 } else { | |
| 8414 // This should be an initialized object that's alive. | |
|
6725
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6197
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|
8415 assert(oop(addr)->klass_or_null() != NULL, |
| 0 | 8416 "Should be an initialized object"); |
| 8417 // Ignore mark word because we are running concurrent with mutators | |
| 8418 assert(oop(addr)->is_oop(true), "live block should be an oop"); | |
| 8419 // Verify that the bit map has no bits marked between | |
| 8420 // addr and purported end of this block. | |
| 8421 size = CompactibleFreeListSpace::adjustObjectSize(oop(addr)->size()); | |
| 8422 assert(size >= 3, "Necessary for Printezis marks to work"); | |
| 8423 assert(!_bitMap->isMarked(addr+1), "Tautology for this control point"); | |
| 8424 DEBUG_ONLY(_bitMap->verifyNoOneBitsInRange(addr+2, addr+size);) | |
| 8425 } | |
| 8426 return size; | |
| 8427 } | |
| 8428 | |
|
2132
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1994
diff
changeset
|
8429 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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|
8430 size_t chunkSize) { |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
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|
8431 // do_post_free_or_garbage_chunk() should only be called in the case |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8432 // of the adaptive free list allocator. |
|
6028
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jmasa
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6026
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changeset
|
8433 const bool fcInFreeLists = fc->is_free(); |
| 0 | 8434 assert(_sp->adaptive_freelists(), "Should only be used in this case."); |
| 8435 assert((HeapWord*)fc <= _limit, "sweep invariant"); | |
| 8436 if (CMSTestInFreeList && fcInFreeLists) { | |
|
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jmasa
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6026
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|
8437 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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|
8438 } |
| 0 | 8439 |
| 8440 if (CMSTraceSweeper) { | |
| 8441 gclog_or_tty->print_cr(" -- pick up another chunk at 0x%x (%d)", fc, chunkSize); | |
| 8442 } | |
| 8443 | |
|
3746
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3356
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|
8444 HeapWord* const fc_addr = (HeapWord*) fc; |
| 0 | 8445 |
| 8446 bool coalesce; | |
|
3746
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|
8447 const size_t left = pointer_delta(fc_addr, freeFinger()); |
|
537a4053b0f9
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|
8448 const size_t right = chunkSize; |
| 0 | 8449 switch (FLSCoalescePolicy) { |
| 8450 // numeric value forms a coalition aggressiveness metric | |
| 8451 case 0: { // never coalesce | |
| 8452 coalesce = false; | |
| 8453 break; | |
| 8454 } | |
| 8455 case 1: { // coalesce if left & right chunks on overpopulated lists | |
| 8456 coalesce = _sp->coalOverPopulated(left) && | |
| 8457 _sp->coalOverPopulated(right); | |
| 8458 break; | |
| 8459 } | |
| 8460 case 2: { // coalesce if left chunk on overpopulated list (default) | |
| 8461 coalesce = _sp->coalOverPopulated(left); | |
| 8462 break; | |
| 8463 } | |
| 8464 case 3: { // coalesce if left OR right chunk on overpopulated list | |
| 8465 coalesce = _sp->coalOverPopulated(left) || | |
| 8466 _sp->coalOverPopulated(right); | |
| 8467 break; | |
| 8468 } | |
| 8469 case 4: { // always coalesce | |
| 8470 coalesce = true; | |
| 8471 break; | |
| 8472 } | |
| 8473 default: | |
| 8474 ShouldNotReachHere(); | |
| 8475 } | |
| 8476 | |
| 8477 // Should the current free range be coalesced? | |
| 8478 // If the chunk is in a free range and either we decided to coalesce above | |
| 8479 // or the chunk is near the large block at the end of the heap | |
| 8480 // (isNearLargestChunk() returns true), then coalesce this chunk. | |
|
3746
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|
8481 const bool doCoalesce = inFreeRange() |
|
537a4053b0f9
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3356
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|
8482 && (coalesce || _g->isNearLargestChunk(fc_addr)); |
| 0 | 8483 if (doCoalesce) { |
| 8484 // Coalesce the current free range on the left with the new | |
| 8485 // chunk on the right. If either is on a free list, | |
| 8486 // it must be removed from the list and stashed in the closure. | |
| 8487 if (freeRangeInFreeLists()) { | |
|
3746
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3356
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|
8488 FreeChunk* const ffc = (FreeChunk*)freeFinger(); |
|
537a4053b0f9
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3356
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|
8489 assert(ffc->size() == pointer_delta(fc_addr, freeFinger()), |
| 0 | 8490 "Size of free range is inconsistent with chunk size."); |
| 8491 if (CMSTestInFreeList) { | |
|
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|
8492 assert(_sp->verify_chunk_in_free_list(ffc), |
| 0 | 8493 "Chunk is not in free lists"); |
| 8494 } | |
| 8495 _sp->coalDeath(ffc->size()); | |
| 8496 _sp->removeFreeChunkFromFreeLists(ffc); | |
| 8497 set_freeRangeInFreeLists(false); | |
| 8498 } | |
| 8499 if (fcInFreeLists) { | |
| 8500 _sp->coalDeath(chunkSize); | |
| 8501 assert(fc->size() == chunkSize, | |
| 8502 "The chunk has the wrong size or is not in the free lists"); | |
| 8503 _sp->removeFreeChunkFromFreeLists(fc); | |
| 8504 } | |
| 8505 set_lastFreeRangeCoalesced(true); | |
|
3746
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3356
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changeset
|
8506 print_free_block_coalesced(fc); |
| 0 | 8507 } else { // not in a free range and/or should not coalesce |
| 8508 // Return the current free range and start a new one. | |
| 8509 if (inFreeRange()) { | |
| 8510 // In a free range but cannot coalesce with the right hand chunk. | |
| 8511 // Put the current free range into the free lists. | |
|
2132
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diff
changeset
|
8512 flush_cur_free_chunk(freeFinger(), |
|
3746
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3356
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changeset
|
8513 pointer_delta(fc_addr, freeFinger())); |
| 0 | 8514 } |
| 8515 // Set up for new free range. Pass along whether the right hand | |
| 8516 // chunk is in the free lists. | |
| 8517 initialize_free_range((HeapWord*)fc, fcInFreeLists); | |
| 8518 } | |
| 8519 } | |
|
2132
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diff
changeset
|
8520 |
|
3746
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ysr
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3356
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changeset
|
8521 // Lookahead flush: |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8522 // 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
|
8523 // 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
|
8524 // flush it along with any free range we may be holding on to. Note that |
|
537a4053b0f9
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|
8525 // this can be the case only for an already free or freshly garbage |
|
537a4053b0f9
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|
8526 // chunk. If this block is an object, it can never straddle |
|
537a4053b0f9
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|
8527 // over _limit. The "straddling" occurs when _limit is set at |
|
537a4053b0f9
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|
8528 // the previous end of the space when this cycle started, and |
|
537a4053b0f9
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|
8529 // a subsequent heap expansion caused the previously co-terminal |
|
537a4053b0f9
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|
8530 // free block to be coalesced with the newly expanded portion, |
|
537a4053b0f9
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|
8531 // thus rendering _limit a non-block-boundary making it dangerous |
|
537a4053b0f9
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|
8532 // for the sweeper to step over and examine. |
|
537a4053b0f9
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|
8533 void SweepClosure::lookahead_and_flush(FreeChunk* fc, size_t chunk_size) { |
|
537a4053b0f9
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|
8534 assert(inFreeRange(), "Should only be called if currently in a free range."); |
|
537a4053b0f9
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|
8535 HeapWord* const eob = ((HeapWord*)fc) + chunk_size; |
|
537a4053b0f9
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|
8536 assert(_sp->used_region().contains(eob - 1), |
|
537a4053b0f9
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|
8537 err_msg("eob = " PTR_FORMAT " out of bounds wrt _sp = [" PTR_FORMAT "," PTR_FORMAT ")" |
|
537a4053b0f9
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|
8538 " when examining fc = " PTR_FORMAT "(" SIZE_FORMAT ")", |
|
537a4053b0f9
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|
8539 _limit, _sp->bottom(), _sp->end(), fc, chunk_size)); |
|
537a4053b0f9
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|
8540 if (eob >= _limit) { |
|
6028
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|
8541 assert(eob == _limit || fc->is_free(), "Only a free chunk should allow us to cross over the limit"); |
|
3746
537a4053b0f9
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|
8542 if (CMSTraceSweeper) { |
|
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|
8543 gclog_or_tty->print_cr("_limit " PTR_FORMAT " reached or crossed by block " |
|
537a4053b0f9
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|
8544 "[" PTR_FORMAT "," PTR_FORMAT ") in space " |
|
537a4053b0f9
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|
8545 "[" PTR_FORMAT "," PTR_FORMAT ")", |
|
537a4053b0f9
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|
8546 _limit, fc, eob, _sp->bottom(), _sp->end()); |
|
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|
8547 } |
|
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|
8548 // Return the storage we are tracking back into the free lists. |
|
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|
8549 if (CMSTraceSweeper) { |
|
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|
8550 gclog_or_tty->print_cr("Flushing ... "); |
|
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|
8551 } |
|
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|
8552 assert(freeFinger() < eob, "Error"); |
|
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|
8553 flush_cur_free_chunk( freeFinger(), pointer_delta(eob, freeFinger())); |
|
537a4053b0f9
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|
8554 } |
|
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|
8555 } |
|
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|
8556 |
|
2132
4947ee68d19c
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|
8557 void SweepClosure::flush_cur_free_chunk(HeapWord* chunk, size_t size) { |
| 0 | 8558 assert(inFreeRange(), "Should only be called if currently in a free range."); |
| 8559 assert(size > 0, | |
| 8560 "A zero sized chunk cannot be added to the free lists."); | |
| 8561 if (!freeRangeInFreeLists()) { | |
|
2132
4947ee68d19c
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diff
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|
8562 if (CMSTestInFreeList) { |
| 0 | 8563 FreeChunk* fc = (FreeChunk*) chunk; |
|
6028
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|
8564 fc->set_size(size); |
|
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|
8565 assert(!_sp->verify_chunk_in_free_list(fc), |
| 0 | 8566 "chunk should not be in free lists yet"); |
| 8567 } | |
| 8568 if (CMSTraceSweeper) { | |
| 8569 gclog_or_tty->print_cr(" -- add free block 0x%x (%d) to free lists", | |
| 8570 chunk, size); | |
| 8571 } | |
| 8572 // A new free range is going to be starting. The current | |
| 8573 // free range has not been added to the free lists yet or | |
| 8574 // was removed so add it back. | |
| 8575 // If the current free range was coalesced, then the death | |
| 8576 // of the free range was recorded. Record a birth now. | |
| 8577 if (lastFreeRangeCoalesced()) { | |
| 8578 _sp->coalBirth(size); | |
| 8579 } | |
| 8580 _sp->addChunkAndRepairOffsetTable(chunk, size, | |
| 8581 lastFreeRangeCoalesced()); | |
|
3746
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|
8582 } else if (CMSTraceSweeper) { |
|
537a4053b0f9
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|
8583 gclog_or_tty->print_cr("Already in free list: nothing to flush"); |
| 0 | 8584 } |
| 8585 set_inFreeRange(false); | |
| 8586 set_freeRangeInFreeLists(false); | |
| 8587 } | |
| 8588 | |
| 8589 // We take a break if we've been at this for a while, | |
| 8590 // so as to avoid monopolizing the locks involved. | |
| 8591 void SweepClosure::do_yield_work(HeapWord* addr) { | |
| 8592 // Return current free chunk being used for coalescing (if any) | |
| 8593 // to the appropriate freelist. After yielding, the next | |
| 8594 // free block encountered will start a coalescing range of | |
| 8595 // free blocks. If the next free block is adjacent to the | |
| 8596 // chunk just flushed, they will need to wait for the next | |
| 8597 // sweep to be coalesced. | |
| 8598 if (inFreeRange()) { | |
|
2132
4947ee68d19c
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1994
diff
changeset
|
8599 flush_cur_free_chunk(freeFinger(), pointer_delta(addr, freeFinger())); |
| 0 | 8600 } |
| 8601 | |
| 8602 // First give up the locks, then yield, then re-lock. | |
| 8603 // We should probably use a constructor/destructor idiom to | |
| 8604 // do this unlock/lock or modify the MutexUnlocker class to | |
| 8605 // serve our purpose. XXX | |
| 8606 assert_lock_strong(_bitMap->lock()); | |
| 8607 assert_lock_strong(_freelistLock); | |
| 8608 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 8609 "CMS thread should hold CMS token"); | |
| 8610 _bitMap->lock()->unlock(); | |
| 8611 _freelistLock->unlock(); | |
| 8612 ConcurrentMarkSweepThread::desynchronize(true); | |
| 8613 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 8614 _collector->stopTimer(); | |
| 8615 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 8616 if (PrintCMSStatistics != 0) { | |
| 8617 _collector->incrementYields(); | |
| 8618 } | |
| 8619 _collector->icms_wait(); | |
| 8620 | |
| 8621 // See the comment in coordinator_yield() | |
| 8622 for (unsigned i = 0; i < CMSYieldSleepCount && | |
| 8623 ConcurrentMarkSweepThread::should_yield() && | |
| 8624 !CMSCollector::foregroundGCIsActive(); ++i) { | |
| 8625 os::sleep(Thread::current(), 1, false); | |
| 8626 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 8627 } | |
| 8628 | |
| 8629 ConcurrentMarkSweepThread::synchronize(true); | |
| 8630 _freelistLock->lock(); | |
| 8631 _bitMap->lock()->lock_without_safepoint_check(); | |
| 8632 _collector->startTimer(); | |
| 8633 } | |
| 8634 | |
| 8635 #ifndef PRODUCT | |
| 8636 // This is actually very useful in a product build if it can | |
| 8637 // be called from the debugger. Compile it into the product | |
| 8638 // as needed. | |
|
6028
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|
8639 bool debug_verify_chunk_in_free_list(FreeChunk* fc) { |
|
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
parents:
6026
diff
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|
8640 return debug_cms_space->verify_chunk_in_free_list(fc); |
| 0 | 8641 } |
|
3746
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|
8642 #endif |
|
537a4053b0f9
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|
8643 |
|
537a4053b0f9
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ysr
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3356
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|
8644 void SweepClosure::print_free_block_coalesced(FreeChunk* fc) const { |
| 0 | 8645 if (CMSTraceSweeper) { |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8646 gclog_or_tty->print_cr("Sweep:coal_free_blk " PTR_FORMAT " (" SIZE_FORMAT ")", |
|
537a4053b0f9
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|
8647 fc, fc->size()); |
|
537a4053b0f9
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|
8648 } |
|
537a4053b0f9
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|
8649 } |
| 0 | 8650 |
| 8651 // CMSIsAliveClosure | |
| 8652 bool CMSIsAliveClosure::do_object_b(oop obj) { | |
| 8653 HeapWord* addr = (HeapWord*)obj; | |
| 8654 return addr != NULL && | |
| 8655 (!_span.contains(addr) || _bit_map->isMarked(addr)); | |
| 8656 } | |
| 8657 | |
|
6725
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
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|
8658 |
| 935 | 8659 CMSKeepAliveClosure::CMSKeepAliveClosure( CMSCollector* collector, |
| 8660 MemRegion span, | |
| 8661 CMSBitMap* bit_map, CMSMarkStack* mark_stack, | |
|
6725
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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|
8662 bool cpc): |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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6197
diff
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|
8663 _collector(collector), |
| 935 | 8664 _span(span), |
| 8665 _bit_map(bit_map), | |
| 8666 _mark_stack(mark_stack), | |
| 8667 _concurrent_precleaning(cpc) { | |
| 8668 assert(!_span.is_empty(), "Empty span could spell trouble"); | |
| 8669 } | |
| 8670 | |
| 8671 | |
| 0 | 8672 // CMSKeepAliveClosure: the serial version |
|
113
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6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
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|
8673 void CMSKeepAliveClosure::do_oop(oop obj) { |
|
ba764ed4b6f2
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|
8674 HeapWord* addr = (HeapWord*)obj; |
| 0 | 8675 if (_span.contains(addr) && |
| 8676 !_bit_map->isMarked(addr)) { | |
| 8677 _bit_map->mark(addr); | |
| 8678 bool simulate_overflow = false; | |
| 8679 NOT_PRODUCT( | |
| 8680 if (CMSMarkStackOverflowALot && | |
| 8681 _collector->simulate_overflow()) { | |
| 8682 // simulate a stack overflow | |
| 8683 simulate_overflow = true; | |
| 8684 } | |
| 8685 ) | |
|
113
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|
8686 if (simulate_overflow || !_mark_stack->push(obj)) { |
|
452
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
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|
8687 if (_concurrent_precleaning) { |
|
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
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360
diff
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|
8688 // We dirty the overflown object and let the remark |
|
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
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360
diff
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|
8689 // phase deal with it. |
|
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
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360
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|
8690 assert(_collector->overflow_list_is_empty(), "Error"); |
|
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
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360
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|
8691 // In the case of object arrays, we need to dirty all of |
|
00b023ae2d78
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360
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|
8692 // the cards that the object spans. No locking or atomics |
|
00b023ae2d78
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360
diff
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|
8693 // are needed since no one else can be mutating the mod union |
|
00b023ae2d78
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360
diff
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|
8694 // table. |
|
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
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360
diff
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|
8695 if (obj->is_objArray()) { |
|
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
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360
diff
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|
8696 size_t sz = obj->size(); |
|
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
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360
diff
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|
8697 HeapWord* end_card_addr = |
|
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
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360
diff
changeset
|
8698 (HeapWord*)round_to((intptr_t)(addr+sz), CardTableModRefBS::card_size); |
|
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
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360
diff
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|
8699 MemRegion redirty_range = MemRegion(addr, end_card_addr); |
|
00b023ae2d78
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360
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|
8700 assert(!redirty_range.is_empty(), "Arithmetical tautology"); |
|
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6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
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360
diff
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|
8701 _collector->_modUnionTable.mark_range(redirty_range); |
|
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
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360
diff
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|
8702 } else { |
|
00b023ae2d78
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360
diff
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|
8703 _collector->_modUnionTable.mark(addr); |
|
00b023ae2d78
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360
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|
8704 } |
|
00b023ae2d78
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ysr
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|
8705 _collector->_ser_kac_preclean_ovflw++; |
|
00b023ae2d78
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|
8706 } else { |
|
00b023ae2d78
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ysr
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|
8707 _collector->push_on_overflow_list(obj); |
|
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
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360
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|
8708 _collector->_ser_kac_ovflw++; |
|
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|
8709 } |
| 0 | 8710 } |
| 8711 } | |
| 8712 } | |
| 8713 | |
|
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|
8714 void CMSKeepAliveClosure::do_oop(oop* p) { CMSKeepAliveClosure::do_oop_work(p); } |
|
ba764ed4b6f2
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94
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|
8715 void CMSKeepAliveClosure::do_oop(narrowOop* p) { CMSKeepAliveClosure::do_oop_work(p); } |
|
ba764ed4b6f2
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94
diff
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|
8716 |
| 0 | 8717 // CMSParKeepAliveClosure: a parallel version of the above. |
| 8718 // The work queues are private to each closure (thread), | |
| 8719 // but (may be) available for stealing by other threads. | |
|
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|
8720 void CMSParKeepAliveClosure::do_oop(oop obj) { |
|
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8721 HeapWord* addr = (HeapWord*)obj; |
| 0 | 8722 if (_span.contains(addr) && |
| 8723 !_bit_map->isMarked(addr)) { | |
| 8724 // In general, during recursive tracing, several threads | |
| 8725 // may be concurrently getting here; the first one to | |
| 8726 // "tag" it, claims it. | |
| 8727 if (_bit_map->par_mark(addr)) { | |
|
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8728 bool res = _work_queue->push(obj); |
| 0 | 8729 assert(res, "Low water mark should be much less than capacity"); |
| 8730 // Do a recursive trim in the hope that this will keep | |
| 8731 // stack usage lower, but leave some oops for potential stealers | |
| 8732 trim_queue(_low_water_mark); | |
| 8733 } // Else, another thread got there first | |
| 8734 } | |
| 8735 } | |
| 8736 | |
|
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8737 void CMSParKeepAliveClosure::do_oop(oop* p) { CMSParKeepAliveClosure::do_oop_work(p); } |
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8738 void CMSParKeepAliveClosure::do_oop(narrowOop* p) { CMSParKeepAliveClosure::do_oop_work(p); } |
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8739 |
| 0 | 8740 void CMSParKeepAliveClosure::trim_queue(uint max) { |
| 8741 while (_work_queue->size() > max) { | |
| 8742 oop new_oop; | |
| 8743 if (_work_queue->pop_local(new_oop)) { | |
| 8744 assert(new_oop != NULL && new_oop->is_oop(), "Expected an oop"); | |
| 8745 assert(_bit_map->isMarked((HeapWord*)new_oop), | |
| 8746 "no white objects on this stack!"); | |
| 8747 assert(_span.contains((HeapWord*)new_oop), "Out of bounds oop"); | |
| 8748 // iterate over the oops in this oop, marking and pushing | |
| 8749 // the ones in CMS heap (i.e. in _span). | |
| 8750 new_oop->oop_iterate(&_mark_and_push); | |
| 8751 } | |
| 8752 } | |
| 8753 } | |
| 8754 | |
| 935 | 8755 CMSInnerParMarkAndPushClosure::CMSInnerParMarkAndPushClosure( |
| 8756 CMSCollector* collector, | |
| 8757 MemRegion span, CMSBitMap* bit_map, | |
| 8758 OopTaskQueue* work_queue): | |
|
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8759 _collector(collector), |
| 935 | 8760 _span(span), |
| 8761 _bit_map(bit_map), | |
| 8762 _work_queue(work_queue) { } | |
| 8763 | |
|
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8764 void CMSInnerParMarkAndPushClosure::do_oop(oop obj) { |
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8765 HeapWord* addr = (HeapWord*)obj; |
| 0 | 8766 if (_span.contains(addr) && |
| 8767 !_bit_map->isMarked(addr)) { | |
| 8768 if (_bit_map->par_mark(addr)) { | |
| 8769 bool simulate_overflow = false; | |
| 8770 NOT_PRODUCT( | |
| 8771 if (CMSMarkStackOverflowALot && | |
| 8772 _collector->par_simulate_overflow()) { | |
| 8773 // simulate a stack overflow | |
| 8774 simulate_overflow = true; | |
| 8775 } | |
| 8776 ) | |
|
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8777 if (simulate_overflow || !_work_queue->push(obj)) { |
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8778 _collector->par_push_on_overflow_list(obj); |
| 0 | 8779 _collector->_par_kac_ovflw++; |
| 8780 } | |
| 8781 } // Else another thread got there already | |
| 8782 } | |
| 8783 } | |
| 8784 | |
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8785 void CMSInnerParMarkAndPushClosure::do_oop(oop* p) { CMSInnerParMarkAndPushClosure::do_oop_work(p); } |
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8786 void CMSInnerParMarkAndPushClosure::do_oop(narrowOop* p) { CMSInnerParMarkAndPushClosure::do_oop_work(p); } |
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8787 |
| 0 | 8788 ////////////////////////////////////////////////////////////////// |
| 8789 // CMSExpansionCause ///////////////////////////// | |
| 8790 ////////////////////////////////////////////////////////////////// | |
| 8791 const char* CMSExpansionCause::to_string(CMSExpansionCause::Cause cause) { | |
| 8792 switch (cause) { | |
| 8793 case _no_expansion: | |
| 8794 return "No expansion"; | |
| 8795 case _satisfy_free_ratio: | |
| 8796 return "Free ratio"; | |
| 8797 case _satisfy_promotion: | |
| 8798 return "Satisfy promotion"; | |
| 8799 case _satisfy_allocation: | |
| 8800 return "allocation"; | |
| 8801 case _allocate_par_lab: | |
| 8802 return "Par LAB"; | |
| 8803 case _allocate_par_spooling_space: | |
| 8804 return "Par Spooling Space"; | |
| 8805 case _adaptive_size_policy: | |
| 8806 return "Ergonomics"; | |
| 8807 default: | |
| 8808 return "unknown"; | |
| 8809 } | |
| 8810 } | |
| 8811 | |
| 8812 void CMSDrainMarkingStackClosure::do_void() { | |
| 8813 // the max number to take from overflow list at a time | |
| 8814 const size_t num = _mark_stack->capacity()/4; | |
|
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8815 assert(!_concurrent_precleaning || _collector->overflow_list_is_empty(), |
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8816 "Overflow list should be NULL during concurrent phases"); |
| 0 | 8817 while (!_mark_stack->isEmpty() || |
| 8818 // if stack is empty, check the overflow list | |
| 8819 _collector->take_from_overflow_list(num, _mark_stack)) { | |
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8820 oop obj = _mark_stack->pop(); |
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8821 HeapWord* addr = (HeapWord*)obj; |
| 0 | 8822 assert(_span.contains(addr), "Should be within span"); |
| 8823 assert(_bit_map->isMarked(addr), "Should be marked"); | |
|
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8824 assert(obj->is_oop(), "Should be an oop"); |
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8825 obj->oop_iterate(_keep_alive); |
| 0 | 8826 } |
| 8827 } | |
| 8828 | |
| 8829 void CMSParDrainMarkingStackClosure::do_void() { | |
| 8830 // drain queue | |
| 8831 trim_queue(0); | |
| 8832 } | |
| 8833 | |
| 8834 // Trim our work_queue so its length is below max at return | |
| 8835 void CMSParDrainMarkingStackClosure::trim_queue(uint max) { | |
| 8836 while (_work_queue->size() > max) { | |
| 8837 oop new_oop; | |
| 8838 if (_work_queue->pop_local(new_oop)) { | |
| 8839 assert(new_oop->is_oop(), "Expected an oop"); | |
| 8840 assert(_bit_map->isMarked((HeapWord*)new_oop), | |
| 8841 "no white objects on this stack!"); | |
| 8842 assert(_span.contains((HeapWord*)new_oop), "Out of bounds oop"); | |
| 8843 // iterate over the oops in this oop, marking and pushing | |
| 8844 // the ones in CMS heap (i.e. in _span). | |
| 8845 new_oop->oop_iterate(&_mark_and_push); | |
| 8846 } | |
| 8847 } | |
| 8848 } | |
| 8849 | |
| 8850 //////////////////////////////////////////////////////////////////// | |
| 8851 // Support for Marking Stack Overflow list handling and related code | |
| 8852 //////////////////////////////////////////////////////////////////// | |
| 8853 // Much of the following code is similar in shape and spirit to the | |
| 8854 // code used in ParNewGC. We should try and share that code | |
| 8855 // as much as possible in the future. | |
| 8856 | |
| 8857 #ifndef PRODUCT | |
| 8858 // Debugging support for CMSStackOverflowALot | |
| 8859 | |
| 8860 // It's OK to call this multi-threaded; the worst thing | |
| 8861 // that can happen is that we'll get a bunch of closely | |
| 8862 // spaced simulated oveflows, but that's OK, in fact | |
| 8863 // probably good as it would exercise the overflow code | |
| 8864 // under contention. | |
| 8865 bool CMSCollector::simulate_overflow() { | |
| 8866 if (_overflow_counter-- <= 0) { // just being defensive | |
| 8867 _overflow_counter = CMSMarkStackOverflowInterval; | |
| 8868 return true; | |
| 8869 } else { | |
| 8870 return false; | |
| 8871 } | |
| 8872 } | |
| 8873 | |
| 8874 bool CMSCollector::par_simulate_overflow() { | |
| 8875 return simulate_overflow(); | |
| 8876 } | |
| 8877 #endif | |
| 8878 | |
| 8879 // Single-threaded | |
| 8880 bool CMSCollector::take_from_overflow_list(size_t num, CMSMarkStack* stack) { | |
| 8881 assert(stack->isEmpty(), "Expected precondition"); | |
| 8882 assert(stack->capacity() > num, "Shouldn't bite more than can chew"); | |
| 8883 size_t i = num; | |
| 8884 oop cur = _overflow_list; | |
| 8885 const markOop proto = markOopDesc::prototype(); | |
| 534 | 8886 NOT_PRODUCT(ssize_t n = 0;) |
| 0 | 8887 for (oop next; i > 0 && cur != NULL; cur = next, i--) { |
| 8888 next = oop(cur->mark()); | |
| 8889 cur->set_mark(proto); // until proven otherwise | |
| 8890 assert(cur->is_oop(), "Should be an oop"); | |
| 8891 bool res = stack->push(cur); | |
| 8892 assert(res, "Bit off more than can chew?"); | |
| 8893 NOT_PRODUCT(n++;) | |
| 8894 } | |
| 8895 _overflow_list = cur; | |
| 8896 #ifndef PRODUCT | |
| 8897 assert(_num_par_pushes >= n, "Too many pops?"); | |
| 8898 _num_par_pushes -=n; | |
| 8899 #endif | |
| 8900 return !stack->isEmpty(); | |
| 8901 } | |
| 8902 | |
| 534 | 8903 #define BUSY (oop(0x1aff1aff)) |
| 8904 // (MT-safe) Get a prefix of at most "num" from the list. | |
| 8905 // The overflow list is chained through the mark word of | |
| 8906 // each object in the list. We fetch the entire list, | |
| 8907 // break off a prefix of the right size and return the | |
| 8908 // remainder. If other threads try to take objects from | |
| 8909 // the overflow list at that time, they will wait for | |
| 8910 // some time to see if data becomes available. If (and | |
| 8911 // only if) another thread places one or more object(s) | |
| 8912 // on the global list before we have returned the suffix | |
| 8913 // to the global list, we will walk down our local list | |
| 8914 // to find its end and append the global list to | |
| 8915 // our suffix before returning it. This suffix walk can | |
| 8916 // prove to be expensive (quadratic in the amount of traffic) | |
| 8917 // when there are many objects in the overflow list and | |
| 8918 // there is much producer-consumer contention on the list. | |
| 8919 // *NOTE*: The overflow list manipulation code here and | |
| 8920 // in ParNewGeneration:: are very similar in shape, | |
| 8921 // except that in the ParNew case we use the old (from/eden) | |
| 8922 // copy of the object to thread the list via its klass word. | |
| 8923 // Because of the common code, if you make any changes in | |
| 8924 // the code below, please check the ParNew version to see if | |
| 8925 // similar changes might be needed. | |
| 8926 // CR 6797058 has been filed to consolidate the common code. | |
| 0 | 8927 bool CMSCollector::par_take_from_overflow_list(size_t num, |
|
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8928 OopTaskQueue* work_q, |
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8929 int no_of_gc_threads) { |
| 534 | 8930 assert(work_q->size() == 0, "First empty local work queue"); |
| 0 | 8931 assert(num < work_q->max_elems(), "Can't bite more than we can chew"); |
| 8932 if (_overflow_list == NULL) { | |
| 8933 return false; | |
| 8934 } | |
| 8935 // Grab the entire list; we'll put back a suffix | |
| 534 | 8936 oop prefix = (oop)Atomic::xchg_ptr(BUSY, &_overflow_list); |
| 8937 Thread* tid = Thread::current(); | |
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8938 // Before "no_of_gc_threads" was introduced CMSOverflowSpinCount was |
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8939 // set to ParallelGCThreads. |
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8940 size_t CMSOverflowSpinCount = (size_t) no_of_gc_threads; // was ParallelGCThreads; |
| 534 | 8941 size_t sleep_time_millis = MAX2((size_t)1, num/100); |
| 8942 // If the list is busy, we spin for a short while, | |
| 8943 // sleeping between attempts to get the list. | |
| 8944 for (size_t spin = 0; prefix == BUSY && spin < CMSOverflowSpinCount; spin++) { | |
| 8945 os::sleep(tid, sleep_time_millis, false); | |
| 8946 if (_overflow_list == NULL) { | |
| 8947 // Nothing left to take | |
| 8948 return false; | |
| 8949 } else if (_overflow_list != BUSY) { | |
| 8950 // Try and grab the prefix | |
| 8951 prefix = (oop)Atomic::xchg_ptr(BUSY, &_overflow_list); | |
| 8952 } | |
| 8953 } | |
| 8954 // If the list was found to be empty, or we spun long | |
| 8955 // enough, we give up and return empty-handed. If we leave | |
| 8956 // the list in the BUSY state below, it must be the case that | |
| 8957 // some other thread holds the overflow list and will set it | |
| 8958 // to a non-BUSY state in the future. | |
| 8959 if (prefix == NULL || prefix == BUSY) { | |
| 8960 // Nothing to take or waited long enough | |
| 8961 if (prefix == NULL) { | |
| 8962 // Write back the NULL in case we overwrote it with BUSY above | |
| 8963 // and it is still the same value. | |
| 8964 (void) Atomic::cmpxchg_ptr(NULL, &_overflow_list, BUSY); | |
| 8965 } | |
| 8966 return false; | |
| 8967 } | |
| 8968 assert(prefix != NULL && prefix != BUSY, "Error"); | |
| 0 | 8969 size_t i = num; |
| 8970 oop cur = prefix; | |
| 534 | 8971 // Walk down the first "num" objects, unless we reach the end. |
| 0 | 8972 for (; i > 1 && cur->mark() != NULL; cur = oop(cur->mark()), i--); |
| 534 | 8973 if (cur->mark() == NULL) { |
| 8974 // We have "num" or fewer elements in the list, so there | |
| 8975 // is nothing to return to the global list. | |
| 8976 // Write back the NULL in lieu of the BUSY we wrote | |
| 8977 // above, if it is still the same value. | |
| 8978 if (_overflow_list == BUSY) { | |
| 8979 (void) Atomic::cmpxchg_ptr(NULL, &_overflow_list, BUSY); | |
| 8980 } | |
| 8981 } else { | |
| 8982 // Chop off the suffix and rerturn it to the global list. | |
| 8983 assert(cur->mark() != BUSY, "Error"); | |
| 0 | 8984 oop suffix_head = cur->mark(); // suffix will be put back on global list |
| 8985 cur->set_mark(NULL); // break off suffix | |
| 534 | 8986 // It's possible that the list is still in the empty(busy) state |
| 8987 // we left it in a short while ago; in that case we may be | |
| 8988 // able to place back the suffix without incurring the cost | |
| 8989 // of a walk down the list. | |
| 0 | 8990 oop observed_overflow_list = _overflow_list; |
| 534 | 8991 oop cur_overflow_list = observed_overflow_list; |
| 8992 bool attached = false; | |
| 8993 while (observed_overflow_list == BUSY || observed_overflow_list == NULL) { | |
| 0 | 8994 observed_overflow_list = |
| 534 | 8995 (oop) Atomic::cmpxchg_ptr(suffix_head, &_overflow_list, cur_overflow_list); |
| 8996 if (cur_overflow_list == observed_overflow_list) { | |
| 8997 attached = true; | |
| 8998 break; | |
| 8999 } else cur_overflow_list = observed_overflow_list; | |
| 9000 } | |
| 9001 if (!attached) { | |
| 9002 // Too bad, someone else sneaked in (at least) an element; we'll need | |
| 9003 // to do a splice. Find tail of suffix so we can prepend suffix to global | |
| 9004 // list. | |
| 9005 for (cur = suffix_head; cur->mark() != NULL; cur = (oop)(cur->mark())); | |
| 9006 oop suffix_tail = cur; | |
| 9007 assert(suffix_tail != NULL && suffix_tail->mark() == NULL, | |
| 9008 "Tautology"); | |
| 9009 observed_overflow_list = _overflow_list; | |
| 9010 do { | |
| 9011 cur_overflow_list = observed_overflow_list; | |
| 9012 if (cur_overflow_list != BUSY) { | |
| 9013 // Do the splice ... | |
| 9014 suffix_tail->set_mark(markOop(cur_overflow_list)); | |
| 9015 } else { // cur_overflow_list == BUSY | |
| 9016 suffix_tail->set_mark(NULL); | |
| 9017 } | |
| 9018 // ... and try to place spliced list back on overflow_list ... | |
| 9019 observed_overflow_list = | |
| 9020 (oop) Atomic::cmpxchg_ptr(suffix_head, &_overflow_list, cur_overflow_list); | |
| 9021 } while (cur_overflow_list != observed_overflow_list); | |
| 9022 // ... until we have succeeded in doing so. | |
| 9023 } | |
| 0 | 9024 } |
| 9025 | |
| 9026 // Push the prefix elements on work_q | |
| 9027 assert(prefix != NULL, "control point invariant"); | |
| 9028 const markOop proto = markOopDesc::prototype(); | |
| 9029 oop next; | |
| 534 | 9030 NOT_PRODUCT(ssize_t n = 0;) |
| 0 | 9031 for (cur = prefix; cur != NULL; cur = next) { |
| 9032 next = oop(cur->mark()); | |
| 9033 cur->set_mark(proto); // until proven otherwise | |
| 9034 assert(cur->is_oop(), "Should be an oop"); | |
| 9035 bool res = work_q->push(cur); | |
| 9036 assert(res, "Bit off more than we can chew?"); | |
| 9037 NOT_PRODUCT(n++;) | |
| 9038 } | |
| 9039 #ifndef PRODUCT | |
| 9040 assert(_num_par_pushes >= n, "Too many pops?"); | |
| 9041 Atomic::add_ptr(-(intptr_t)n, &_num_par_pushes); | |
| 9042 #endif | |
| 9043 return true; | |
| 9044 } | |
| 9045 | |
| 9046 // Single-threaded | |
| 9047 void CMSCollector::push_on_overflow_list(oop p) { | |
| 9048 NOT_PRODUCT(_num_par_pushes++;) | |
| 9049 assert(p->is_oop(), "Not an oop"); | |
| 9050 preserve_mark_if_necessary(p); | |
| 9051 p->set_mark((markOop)_overflow_list); | |
| 9052 _overflow_list = p; | |
| 9053 } | |
| 9054 | |
| 9055 // Multi-threaded; use CAS to prepend to overflow list | |
| 9056 void CMSCollector::par_push_on_overflow_list(oop p) { | |
| 9057 NOT_PRODUCT(Atomic::inc_ptr(&_num_par_pushes);) | |
| 9058 assert(p->is_oop(), "Not an oop"); | |
| 9059 par_preserve_mark_if_necessary(p); | |
| 9060 oop observed_overflow_list = _overflow_list; | |
| 9061 oop cur_overflow_list; | |
| 9062 do { | |
| 9063 cur_overflow_list = observed_overflow_list; | |
| 534 | 9064 if (cur_overflow_list != BUSY) { |
| 9065 p->set_mark(markOop(cur_overflow_list)); | |
| 9066 } else { | |
| 9067 p->set_mark(NULL); | |
| 9068 } | |
| 0 | 9069 observed_overflow_list = |
| 9070 (oop) Atomic::cmpxchg_ptr(p, &_overflow_list, cur_overflow_list); | |
| 9071 } while (cur_overflow_list != observed_overflow_list); | |
| 9072 } | |
| 534 | 9073 #undef BUSY |
| 0 | 9074 |
| 9075 // Single threaded | |
| 9076 // General Note on GrowableArray: pushes may silently fail | |
| 9077 // because we are (temporarily) out of C-heap for expanding | |
| 9078 // the stack. The problem is quite ubiquitous and affects | |
| 9079 // a lot of code in the JVM. The prudent thing for GrowableArray | |
| 9080 // to do (for now) is to exit with an error. However, that may | |
| 9081 // be too draconian in some cases because the caller may be | |
| 534 | 9082 // able to recover without much harm. For such cases, we |
| 0 | 9083 // should probably introduce a "soft_push" method which returns |
| 9084 // an indication of success or failure with the assumption that | |
| 9085 // the caller may be able to recover from a failure; code in | |
| 9086 // the VM can then be changed, incrementally, to deal with such | |
| 9087 // failures where possible, thus, incrementally hardening the VM | |
| 9088 // in such low resource situations. | |
| 9089 void CMSCollector::preserve_mark_work(oop p, markOop m) { | |
|
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9090 _preserved_oop_stack.push(p); |
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9091 _preserved_mark_stack.push(m); |
| 0 | 9092 assert(m == p->mark(), "Mark word changed"); |
|
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9093 assert(_preserved_oop_stack.size() == _preserved_mark_stack.size(), |
| 0 | 9094 "bijection"); |
| 9095 } | |
| 9096 | |
| 9097 // Single threaded | |
| 9098 void CMSCollector::preserve_mark_if_necessary(oop p) { | |
| 9099 markOop m = p->mark(); | |
| 9100 if (m->must_be_preserved(p)) { | |
| 9101 preserve_mark_work(p, m); | |
| 9102 } | |
| 9103 } | |
| 9104 | |
| 9105 void CMSCollector::par_preserve_mark_if_necessary(oop p) { | |
| 9106 markOop m = p->mark(); | |
| 9107 if (m->must_be_preserved(p)) { | |
| 9108 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); | |
| 9109 // Even though we read the mark word without holding | |
| 9110 // the lock, we are assured that it will not change | |
| 9111 // because we "own" this oop, so no other thread can | |
| 9112 // be trying to push it on the overflow list; see | |
| 9113 // the assertion in preserve_mark_work() that checks | |
| 9114 // that m == p->mark(). | |
| 9115 preserve_mark_work(p, m); | |
| 9116 } | |
| 9117 } | |
| 9118 | |
| 9119 // We should be able to do this multi-threaded, | |
| 9120 // a chunk of stack being a task (this is | |
| 9121 // correct because each oop only ever appears | |
| 9122 // once in the overflow list. However, it's | |
| 9123 // not very easy to completely overlap this with | |
| 9124 // other operations, so will generally not be done | |
| 9125 // until all work's been completed. Because we | |
| 9126 // expect the preserved oop stack (set) to be small, | |
| 9127 // it's probably fine to do this single-threaded. | |
| 9128 // We can explore cleverer concurrent/overlapped/parallel | |
| 9129 // processing of preserved marks if we feel the | |
| 9130 // need for this in the future. Stack overflow should | |
| 9131 // be so rare in practice and, when it happens, its | |
| 9132 // effect on performance so great that this will | |
| 9133 // likely just be in the noise anyway. | |
| 9134 void CMSCollector::restore_preserved_marks_if_any() { | |
| 9135 assert(SafepointSynchronize::is_at_safepoint(), | |
| 9136 "world should be stopped"); | |
| 9137 assert(Thread::current()->is_ConcurrentGC_thread() || | |
| 9138 Thread::current()->is_VM_thread(), | |
| 9139 "should be single-threaded"); | |
|
1836
894b1d7c7e01
6423256: GC stacks should use a better data structure
jcoomes
parents:
1833
diff
changeset
|
9140 assert(_preserved_oop_stack.size() == _preserved_mark_stack.size(), |
|
894b1d7c7e01
6423256: GC stacks should use a better data structure
jcoomes
parents:
1833
diff
changeset
|
9141 "bijection"); |
|
894b1d7c7e01
6423256: GC stacks should use a better data structure
jcoomes
parents:
1833
diff
changeset
|
9142 |
|
894b1d7c7e01
6423256: GC stacks should use a better data structure
jcoomes
parents:
1833
diff
changeset
|
9143 while (!_preserved_oop_stack.is_empty()) { |
|
894b1d7c7e01
6423256: GC stacks should use a better data structure
jcoomes
parents:
1833
diff
changeset
|
9144 oop p = _preserved_oop_stack.pop(); |
| 0 | 9145 assert(p->is_oop(), "Should be an oop"); |
| 9146 assert(_span.contains(p), "oop should be in _span"); | |
| 9147 assert(p->mark() == markOopDesc::prototype(), | |
| 9148 "Set when taken from overflow list"); | |
|
1836
894b1d7c7e01
6423256: GC stacks should use a better data structure
jcoomes
parents:
1833
diff
changeset
|
9149 markOop m = _preserved_mark_stack.pop(); |
| 0 | 9150 p->set_mark(m); |
| 9151 } | |
|
1836
894b1d7c7e01
6423256: GC stacks should use a better data structure
jcoomes
parents:
1833
diff
changeset
|
9152 assert(_preserved_mark_stack.is_empty() && _preserved_oop_stack.is_empty(), |
| 0 | 9153 "stacks were cleared above"); |
| 9154 } | |
| 9155 | |
| 9156 #ifndef PRODUCT | |
| 9157 bool CMSCollector::no_preserved_marks() const { | |
|
1836
894b1d7c7e01
6423256: GC stacks should use a better data structure
jcoomes
parents:
1833
diff
changeset
|
9158 return _preserved_mark_stack.is_empty() && _preserved_oop_stack.is_empty(); |
| 0 | 9159 } |
| 9160 #endif | |
| 9161 | |
| 9162 CMSAdaptiveSizePolicy* ASConcurrentMarkSweepGeneration::cms_size_policy() const | |
| 9163 { | |
| 9164 GenCollectedHeap* gch = (GenCollectedHeap*) GenCollectedHeap::heap(); | |
| 9165 CMSAdaptiveSizePolicy* size_policy = | |
| 9166 (CMSAdaptiveSizePolicy*) gch->gen_policy()->size_policy(); | |
| 9167 assert(size_policy->is_gc_cms_adaptive_size_policy(), | |
| 9168 "Wrong type for size policy"); | |
| 9169 return size_policy; | |
| 9170 } | |
| 9171 | |
| 9172 void ASConcurrentMarkSweepGeneration::resize(size_t cur_promo_size, | |
| 9173 size_t desired_promo_size) { | |
| 9174 if (cur_promo_size < desired_promo_size) { | |
| 9175 size_t expand_bytes = desired_promo_size - cur_promo_size; | |
| 9176 if (PrintAdaptiveSizePolicy && Verbose) { | |
| 9177 gclog_or_tty->print_cr(" ASConcurrentMarkSweepGeneration::resize " | |
| 9178 "Expanding tenured generation by " SIZE_FORMAT " (bytes)", | |
| 9179 expand_bytes); | |
| 9180 } | |
| 9181 expand(expand_bytes, | |
| 9182 MinHeapDeltaBytes, | |
| 9183 CMSExpansionCause::_adaptive_size_policy); | |
| 9184 } else if (desired_promo_size < cur_promo_size) { | |
| 9185 size_t shrink_bytes = cur_promo_size - desired_promo_size; | |
| 9186 if (PrintAdaptiveSizePolicy && Verbose) { | |
| 9187 gclog_or_tty->print_cr(" ASConcurrentMarkSweepGeneration::resize " | |
| 9188 "Shrinking tenured generation by " SIZE_FORMAT " (bytes)", | |
| 9189 shrink_bytes); | |
| 9190 } | |
| 9191 shrink(shrink_bytes); | |
| 9192 } | |
| 9193 } | |
| 9194 | |
| 9195 CMSGCAdaptivePolicyCounters* ASConcurrentMarkSweepGeneration::gc_adaptive_policy_counters() { | |
| 9196 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 9197 CMSGCAdaptivePolicyCounters* counters = | |
| 9198 (CMSGCAdaptivePolicyCounters*) gch->collector_policy()->counters(); | |
| 9199 assert(counters->kind() == GCPolicyCounters::CMSGCAdaptivePolicyCountersKind, | |
| 9200 "Wrong kind of counters"); | |
| 9201 return counters; | |
| 9202 } | |
| 9203 | |
| 9204 | |
| 9205 void ASConcurrentMarkSweepGeneration::update_counters() { | |
| 9206 if (UsePerfData) { | |
| 9207 _space_counters->update_all(); | |
| 9208 _gen_counters->update_all(); | |
| 9209 CMSGCAdaptivePolicyCounters* counters = gc_adaptive_policy_counters(); | |
| 9210 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 9211 CMSGCStats* gc_stats_l = (CMSGCStats*) gc_stats(); | |
| 9212 assert(gc_stats_l->kind() == GCStats::CMSGCStatsKind, | |
| 9213 "Wrong gc statistics type"); | |
| 9214 counters->update_counters(gc_stats_l); | |
| 9215 } | |
| 9216 } | |
| 9217 | |
| 9218 void ASConcurrentMarkSweepGeneration::update_counters(size_t used) { | |
| 9219 if (UsePerfData) { | |
| 9220 _space_counters->update_used(used); | |
| 9221 _space_counters->update_capacity(); | |
| 9222 _gen_counters->update_all(); | |
| 9223 | |
| 9224 CMSGCAdaptivePolicyCounters* counters = gc_adaptive_policy_counters(); | |
| 9225 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 9226 CMSGCStats* gc_stats_l = (CMSGCStats*) gc_stats(); | |
| 9227 assert(gc_stats_l->kind() == GCStats::CMSGCStatsKind, | |
| 9228 "Wrong gc statistics type"); | |
| 9229 counters->update_counters(gc_stats_l); | |
| 9230 } | |
| 9231 } | |
| 9232 | |
| 9233 void ASConcurrentMarkSweepGeneration::shrink_by(size_t desired_bytes) { | |
| 9234 assert_locked_or_safepoint(Heap_lock); | |
| 9235 assert_lock_strong(freelistLock()); | |
| 9236 HeapWord* old_end = _cmsSpace->end(); | |
| 9237 HeapWord* unallocated_start = _cmsSpace->unallocated_block(); | |
| 9238 assert(old_end >= unallocated_start, "Miscalculation of unallocated_start"); | |
| 9239 FreeChunk* chunk_at_end = find_chunk_at_end(); | |
| 9240 if (chunk_at_end == NULL) { | |
| 9241 // No room to shrink | |
| 9242 if (PrintGCDetails && Verbose) { | |
| 9243 gclog_or_tty->print_cr("No room to shrink: old_end " | |
| 9244 PTR_FORMAT " unallocated_start " PTR_FORMAT | |
| 9245 " chunk_at_end " PTR_FORMAT, | |
| 9246 old_end, unallocated_start, chunk_at_end); | |
| 9247 } | |
| 9248 return; | |
| 9249 } else { | |
| 9250 | |
| 9251 // Find the chunk at the end of the space and determine | |
| 9252 // how much it can be shrunk. | |
| 9253 size_t shrinkable_size_in_bytes = chunk_at_end->size(); | |
| 9254 size_t aligned_shrinkable_size_in_bytes = | |
| 9255 align_size_down(shrinkable_size_in_bytes, os::vm_page_size()); | |
| 6885 | 9256 assert(unallocated_start <= (HeapWord*) chunk_at_end->end(), |
| 0 | 9257 "Inconsistent chunk at end of space"); |
| 9258 size_t bytes = MIN2(desired_bytes, aligned_shrinkable_size_in_bytes); | |
| 9259 size_t word_size_before = heap_word_size(_virtual_space.committed_size()); | |
| 9260 | |
| 9261 // Shrink the underlying space | |
| 9262 _virtual_space.shrink_by(bytes); | |
| 9263 if (PrintGCDetails && Verbose) { | |
| 9264 gclog_or_tty->print_cr("ConcurrentMarkSweepGeneration::shrink_by:" | |
| 9265 " desired_bytes " SIZE_FORMAT | |
| 9266 " shrinkable_size_in_bytes " SIZE_FORMAT | |
| 9267 " aligned_shrinkable_size_in_bytes " SIZE_FORMAT | |
| 9268 " bytes " SIZE_FORMAT, | |
| 9269 desired_bytes, shrinkable_size_in_bytes, | |
| 9270 aligned_shrinkable_size_in_bytes, bytes); | |
| 9271 gclog_or_tty->print_cr(" old_end " SIZE_FORMAT | |
| 9272 " unallocated_start " SIZE_FORMAT, | |
| 9273 old_end, unallocated_start); | |
| 9274 } | |
| 9275 | |
| 9276 // If the space did shrink (shrinking is not guaranteed), | |
| 9277 // shrink the chunk at the end by the appropriate amount. | |
| 9278 if (((HeapWord*)_virtual_space.high()) < old_end) { | |
| 9279 size_t new_word_size = | |
| 9280 heap_word_size(_virtual_space.committed_size()); | |
| 9281 | |
| 9282 // Have to remove the chunk from the dictionary because it is changing | |
| 9283 // size and might be someplace elsewhere in the dictionary. | |
| 9284 | |
| 9285 // Get the chunk at end, shrink it, and put it | |
| 9286 // back. | |
| 9287 _cmsSpace->removeChunkFromDictionary(chunk_at_end); | |
| 9288 size_t word_size_change = word_size_before - new_word_size; | |
| 9289 size_t chunk_at_end_old_size = chunk_at_end->size(); | |
| 9290 assert(chunk_at_end_old_size >= word_size_change, | |
| 9291 "Shrink is too large"); | |
|
6028
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
parents:
6026
diff
changeset
|
9292 chunk_at_end->set_size(chunk_at_end_old_size - |
| 0 | 9293 word_size_change); |
| 9294 _cmsSpace->freed((HeapWord*) chunk_at_end->end(), | |
| 9295 word_size_change); | |
| 9296 | |
| 9297 _cmsSpace->returnChunkToDictionary(chunk_at_end); | |
| 9298 | |
| 9299 MemRegion mr(_cmsSpace->bottom(), new_word_size); | |
| 9300 _bts->resize(new_word_size); // resize the block offset shared array | |
| 9301 Universe::heap()->barrier_set()->resize_covered_region(mr); | |
| 9302 _cmsSpace->assert_locked(); | |
| 9303 _cmsSpace->set_end((HeapWord*)_virtual_space.high()); | |
| 9304 | |
| 9305 NOT_PRODUCT(_cmsSpace->dictionary()->verify()); | |
| 9306 | |
| 9307 // update the space and generation capacity counters | |
| 9308 if (UsePerfData) { | |
| 9309 _space_counters->update_capacity(); | |
| 9310 _gen_counters->update_all(); | |
| 9311 } | |
| 9312 | |
| 9313 if (Verbose && PrintGCDetails) { | |
| 9314 size_t new_mem_size = _virtual_space.committed_size(); | |
| 9315 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
|
9316 gclog_or_tty->print_cr("Shrinking %s from " SIZE_FORMAT "K by " SIZE_FORMAT "K to " SIZE_FORMAT "K", |
| 0 | 9317 name(), old_mem_size/K, bytes/K, new_mem_size/K); |
| 9318 } | |
| 9319 } | |
| 9320 | |
| 9321 assert(_cmsSpace->unallocated_block() <= _cmsSpace->end(), | |
| 9322 "Inconsistency at end of space"); | |
| 6885 | 9323 assert(chunk_at_end->end() == (uintptr_t*) _cmsSpace->end(), |
| 0 | 9324 "Shrinking is inconsistent"); |
| 9325 return; | |
| 9326 } | |
| 9327 } | |
| 9328 | |
| 9329 // Transfer some number of overflown objects to usual marking | |
| 9330 // stack. Return true if some objects were transferred. | |
| 9331 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
|
9332 size_t num = MIN2((size_t)(_mark_stack->capacity() - _mark_stack->length())/4, |
| 0 | 9333 (size_t)ParGCDesiredObjsFromOverflowList); |
| 9334 | |
| 9335 bool res = _collector->take_from_overflow_list(num, _mark_stack); | |
| 9336 assert(_collector->overflow_list_is_empty() || res, | |
| 9337 "If list is not empty, we should have taken something"); | |
| 9338 assert(!res || !_mark_stack->isEmpty(), | |
| 9339 "If we took something, it should now be on our stack"); | |
| 9340 return res; | |
| 9341 } | |
| 9342 | |
| 9343 size_t MarkDeadObjectsClosure::do_blk(HeapWord* addr) { | |
| 9344 size_t res = _sp->block_size_no_stall(addr, _collector); | |
| 9345 if (_sp->block_is_obj(addr)) { | |
| 9346 if (_live_bit_map->isMarked(addr)) { | |
| 9347 // It can't have been dead in a previous cycle | |
| 9348 guarantee(!_dead_bit_map->isMarked(addr), "No resurrection!"); | |
| 9349 } else { | |
| 9350 _dead_bit_map->mark(addr); // mark the dead object | |
| 9351 } | |
| 9352 } | |
|
2226
c5a923563727
6912621: iCMS: Error: assert(_markBitMap.isMarked(addr + 1),"Missing Printezis bit?")
ysr
parents:
2177
diff
changeset
|
9353 // Could be 0, if the block size could not be computed without stalling. |
| 0 | 9354 return res; |
| 9355 } | |
|
1703
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9356 |
|
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
parents:
3293
diff
changeset
|
9357 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
|
9358 |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9359 switch (phase) { |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9360 case CMSCollector::InitialMarking: |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9361 initialize(true /* fullGC */ , |
|
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
parents:
3293
diff
changeset
|
9362 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
|
9363 true /* recordGCBeginTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9364 true /* recordPreGCUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9365 false /* recordPeakUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9366 false /* recordPostGCusage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9367 true /* recordAccumulatedGCTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9368 false /* recordGCEndTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9369 false /* countCollection */ ); |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9370 break; |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9371 |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9372 case CMSCollector::FinalMarking: |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9373 initialize(true /* fullGC */ , |
|
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
parents:
3293
diff
changeset
|
9374 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
|
9375 false /* recordGCBeginTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9376 false /* recordPreGCUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9377 false /* recordPeakUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9378 false /* recordPostGCusage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9379 true /* recordAccumulatedGCTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9380 false /* recordGCEndTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9381 false /* countCollection */ ); |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9382 break; |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9383 |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9384 case CMSCollector::Sweeping: |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9385 initialize(true /* fullGC */ , |
|
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
parents:
3293
diff
changeset
|
9386 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
|
9387 false /* recordGCBeginTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9388 false /* recordPreGCUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9389 true /* recordPeakUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9390 true /* recordPostGCusage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9391 false /* recordAccumulatedGCTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9392 true /* recordGCEndTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9393 true /* countCollection */ ); |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9394 break; |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9395 |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9396 default: |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9397 ShouldNotReachHere(); |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9398 } |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9399 } |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9400 |