Mercurial > hg > truffle
annotate src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp @ 3746:537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
Summary: Do a one-step look-ahead, when sweeping free or garbage blocks, to avoid overstepping sweep limit, which may become a non-block-boundary because of a heap expansion delta coalescing with a previously co-terminal free block.
Reviewed-by: brutisso, tonyp
| author | ysr |
|---|---|
| date | Mon, 23 May 2011 16:42:14 -0700 |
| parents | 78542e2b5e35 |
| children | 48048b59a551 |
| rev | line source |
|---|---|
| 0 | 1 /* |
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2 * Copyright (c) 2001, 2011, 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" |
| 26 #include "classfile/symbolTable.hpp" | |
| 27 #include "classfile/systemDictionary.hpp" | |
| 28 #include "code/codeCache.hpp" | |
| 29 #include "gc_implementation/concurrentMarkSweep/cmsAdaptiveSizePolicy.hpp" | |
| 30 #include "gc_implementation/concurrentMarkSweep/cmsCollectorPolicy.hpp" | |
| 31 #include "gc_implementation/concurrentMarkSweep/cmsGCAdaptivePolicyCounters.hpp" | |
| 32 #include "gc_implementation/concurrentMarkSweep/cmsOopClosures.inline.hpp" | |
| 33 #include "gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.hpp" | |
| 34 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.inline.hpp" | |
| 35 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp" | |
| 36 #include "gc_implementation/concurrentMarkSweep/vmCMSOperations.hpp" | |
| 37 #include "gc_implementation/parNew/parNewGeneration.hpp" | |
| 38 #include "gc_implementation/shared/collectorCounters.hpp" | |
| 39 #include "gc_implementation/shared/isGCActiveMark.hpp" | |
| 40 #include "gc_interface/collectedHeap.inline.hpp" | |
| 41 #include "memory/cardTableRS.hpp" | |
| 42 #include "memory/collectorPolicy.hpp" | |
| 43 #include "memory/gcLocker.inline.hpp" | |
| 44 #include "memory/genCollectedHeap.hpp" | |
| 45 #include "memory/genMarkSweep.hpp" | |
| 46 #include "memory/genOopClosures.inline.hpp" | |
| 47 #include "memory/iterator.hpp" | |
| 48 #include "memory/referencePolicy.hpp" | |
| 49 #include "memory/resourceArea.hpp" | |
| 50 #include "oops/oop.inline.hpp" | |
| 51 #include "prims/jvmtiExport.hpp" | |
| 52 #include "runtime/globals_extension.hpp" | |
| 53 #include "runtime/handles.inline.hpp" | |
| 54 #include "runtime/java.hpp" | |
| 55 #include "runtime/vmThread.hpp" | |
| 56 #include "services/memoryService.hpp" | |
| 57 #include "services/runtimeService.hpp" | |
| 0 | 58 |
| 59 // statics | |
| 60 CMSCollector* ConcurrentMarkSweepGeneration::_collector = NULL; | |
| 61 bool CMSCollector::_full_gc_requested = false; | |
| 62 | |
| 63 ////////////////////////////////////////////////////////////////// | |
| 64 // In support of CMS/VM thread synchronization | |
| 65 ////////////////////////////////////////////////////////////////// | |
| 66 // We split use of the CGC_lock into 2 "levels". | |
| 67 // The low-level locking is of the usual CGC_lock monitor. We introduce | |
| 68 // a higher level "token" (hereafter "CMS token") built on top of the | |
| 69 // low level monitor (hereafter "CGC lock"). | |
| 70 // The token-passing protocol gives priority to the VM thread. The | |
| 71 // CMS-lock doesn't provide any fairness guarantees, but clients | |
| 72 // should ensure that it is only held for very short, bounded | |
| 73 // durations. | |
| 74 // | |
| 75 // When either of the CMS thread or the VM thread is involved in | |
| 76 // collection operations during which it does not want the other | |
| 77 // thread to interfere, it obtains the CMS token. | |
| 78 // | |
| 79 // If either thread tries to get the token while the other has | |
| 80 // it, that thread waits. However, if the VM thread and CMS thread | |
| 81 // both want the token, then the VM thread gets priority while the | |
| 82 // CMS thread waits. This ensures, for instance, that the "concurrent" | |
| 83 // phases of the CMS thread's work do not block out the VM thread | |
| 84 // for long periods of time as the CMS thread continues to hog | |
| 85 // the token. (See bug 4616232). | |
| 86 // | |
| 87 // The baton-passing functions are, however, controlled by the | |
| 88 // flags _foregroundGCShouldWait and _foregroundGCIsActive, | |
| 89 // and here the low-level CMS lock, not the high level token, | |
| 90 // ensures mutual exclusion. | |
| 91 // | |
| 92 // Two important conditions that we have to satisfy: | |
| 93 // 1. if a thread does a low-level wait on the CMS lock, then it | |
| 94 // relinquishes the CMS token if it were holding that token | |
| 95 // when it acquired the low-level CMS lock. | |
| 96 // 2. any low-level notifications on the low-level lock | |
| 97 // should only be sent when a thread has relinquished the token. | |
| 98 // | |
| 99 // In the absence of either property, we'd have potential deadlock. | |
| 100 // | |
| 101 // We protect each of the CMS (concurrent and sequential) phases | |
| 102 // with the CMS _token_, not the CMS _lock_. | |
| 103 // | |
| 104 // The only code protected by CMS lock is the token acquisition code | |
| 105 // itself, see ConcurrentMarkSweepThread::[de]synchronize(), and the | |
| 106 // baton-passing code. | |
| 107 // | |
| 108 // Unfortunately, i couldn't come up with a good abstraction to factor and | |
| 109 // hide the naked CGC_lock manipulation in the baton-passing code | |
| 110 // further below. That's something we should try to do. Also, the proof | |
| 111 // of correctness of this 2-level locking scheme is far from obvious, | |
| 112 // and potentially quite slippery. We have an uneasy supsicion, for instance, | |
| 113 // that there may be a theoretical possibility of delay/starvation in the | |
| 114 // low-level lock/wait/notify scheme used for the baton-passing because of | |
| 115 // potential intereference with the priority scheme embodied in the | |
| 116 // CMS-token-passing protocol. See related comments at a CGC_lock->wait() | |
| 117 // invocation further below and marked with "XXX 20011219YSR". | |
| 118 // Indeed, as we note elsewhere, this may become yet more slippery | |
| 119 // in the presence of multiple CMS and/or multiple VM threads. XXX | |
| 120 | |
| 121 class CMSTokenSync: public StackObj { | |
| 122 private: | |
| 123 bool _is_cms_thread; | |
| 124 public: | |
| 125 CMSTokenSync(bool is_cms_thread): | |
| 126 _is_cms_thread(is_cms_thread) { | |
| 127 assert(is_cms_thread == Thread::current()->is_ConcurrentGC_thread(), | |
| 128 "Incorrect argument to constructor"); | |
| 129 ConcurrentMarkSweepThread::synchronize(_is_cms_thread); | |
| 130 } | |
| 131 | |
| 132 ~CMSTokenSync() { | |
| 133 assert(_is_cms_thread ? | |
| 134 ConcurrentMarkSweepThread::cms_thread_has_cms_token() : | |
| 135 ConcurrentMarkSweepThread::vm_thread_has_cms_token(), | |
| 136 "Incorrect state"); | |
| 137 ConcurrentMarkSweepThread::desynchronize(_is_cms_thread); | |
| 138 } | |
| 139 }; | |
| 140 | |
| 141 // Convenience class that does a CMSTokenSync, and then acquires | |
| 142 // upto three locks. | |
| 143 class CMSTokenSyncWithLocks: public CMSTokenSync { | |
| 144 private: | |
| 145 // Note: locks are acquired in textual declaration order | |
| 146 // and released in the opposite order | |
| 147 MutexLockerEx _locker1, _locker2, _locker3; | |
| 148 public: | |
| 149 CMSTokenSyncWithLocks(bool is_cms_thread, Mutex* mutex1, | |
| 150 Mutex* mutex2 = NULL, Mutex* mutex3 = NULL): | |
| 151 CMSTokenSync(is_cms_thread), | |
| 152 _locker1(mutex1, Mutex::_no_safepoint_check_flag), | |
| 153 _locker2(mutex2, Mutex::_no_safepoint_check_flag), | |
| 154 _locker3(mutex3, Mutex::_no_safepoint_check_flag) | |
| 155 { } | |
| 156 }; | |
| 157 | |
| 158 | |
| 159 // Wrapper class to temporarily disable icms during a foreground cms collection. | |
| 160 class ICMSDisabler: public StackObj { | |
| 161 public: | |
| 162 // The ctor disables icms and wakes up the thread so it notices the change; | |
| 163 // the dtor re-enables icms. Note that the CMSCollector methods will check | |
| 164 // CMSIncrementalMode. | |
| 165 ICMSDisabler() { CMSCollector::disable_icms(); CMSCollector::start_icms(); } | |
| 166 ~ICMSDisabler() { CMSCollector::enable_icms(); } | |
| 167 }; | |
| 168 | |
| 169 ////////////////////////////////////////////////////////////////// | |
| 170 // Concurrent Mark-Sweep Generation ///////////////////////////// | |
| 171 ////////////////////////////////////////////////////////////////// | |
| 172 | |
| 173 NOT_PRODUCT(CompactibleFreeListSpace* debug_cms_space;) | |
| 174 | |
| 175 // This struct contains per-thread things necessary to support parallel | |
| 176 // young-gen collection. | |
| 177 class CMSParGCThreadState: public CHeapObj { | |
| 178 public: | |
| 179 CFLS_LAB lab; | |
| 180 PromotionInfo promo; | |
| 181 | |
| 182 // Constructor. | |
| 183 CMSParGCThreadState(CompactibleFreeListSpace* cfls) : lab(cfls) { | |
| 184 promo.setSpace(cfls); | |
| 185 } | |
| 186 }; | |
| 187 | |
| 188 ConcurrentMarkSweepGeneration::ConcurrentMarkSweepGeneration( | |
| 189 ReservedSpace rs, size_t initial_byte_size, int level, | |
| 190 CardTableRS* ct, bool use_adaptive_freelists, | |
| 191 FreeBlockDictionary::DictionaryChoice dictionaryChoice) : | |
| 192 CardGeneration(rs, initial_byte_size, level, ct), | |
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193 _dilatation_factor(((double)MinChunkSize)/((double)(CollectedHeap::min_fill_size()))), |
| 0 | 194 _debug_collection_type(Concurrent_collection_type) |
| 195 { | |
| 196 HeapWord* bottom = (HeapWord*) _virtual_space.low(); | |
| 197 HeapWord* end = (HeapWord*) _virtual_space.high(); | |
| 198 | |
| 199 _direct_allocated_words = 0; | |
| 200 NOT_PRODUCT( | |
| 201 _numObjectsPromoted = 0; | |
| 202 _numWordsPromoted = 0; | |
| 203 _numObjectsAllocated = 0; | |
| 204 _numWordsAllocated = 0; | |
| 205 ) | |
| 206 | |
| 207 _cmsSpace = new CompactibleFreeListSpace(_bts, MemRegion(bottom, end), | |
| 208 use_adaptive_freelists, | |
| 209 dictionaryChoice); | |
| 210 NOT_PRODUCT(debug_cms_space = _cmsSpace;) | |
| 211 if (_cmsSpace == NULL) { | |
| 212 vm_exit_during_initialization( | |
| 213 "CompactibleFreeListSpace allocation failure"); | |
| 214 } | |
| 215 _cmsSpace->_gen = this; | |
| 216 | |
| 217 _gc_stats = new CMSGCStats(); | |
| 218 | |
| 219 // Verify the assumption that FreeChunk::_prev and OopDesc::_klass | |
| 220 // offsets match. The ability to tell free chunks from objects | |
| 221 // depends on this property. | |
| 222 debug_only( | |
| 223 FreeChunk* junk = NULL; | |
| 187 | 224 assert(UseCompressedOops || |
| 225 junk->prev_addr() == (void*)(oop(junk)->klass_addr()), | |
| 0 | 226 "Offset of FreeChunk::_prev within FreeChunk must match" |
| 227 " that of OopDesc::_klass within OopDesc"); | |
| 228 ) | |
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229 if (CollectedHeap::use_parallel_gc_threads()) { |
| 0 | 230 typedef CMSParGCThreadState* CMSParGCThreadStatePtr; |
| 231 _par_gc_thread_states = | |
| 232 NEW_C_HEAP_ARRAY(CMSParGCThreadStatePtr, ParallelGCThreads); | |
| 233 if (_par_gc_thread_states == NULL) { | |
| 234 vm_exit_during_initialization("Could not allocate par gc structs"); | |
| 235 } | |
| 236 for (uint i = 0; i < ParallelGCThreads; i++) { | |
| 237 _par_gc_thread_states[i] = new CMSParGCThreadState(cmsSpace()); | |
| 238 if (_par_gc_thread_states[i] == NULL) { | |
| 239 vm_exit_during_initialization("Could not allocate par gc structs"); | |
| 240 } | |
| 241 } | |
| 242 } else { | |
| 243 _par_gc_thread_states = NULL; | |
| 244 } | |
| 245 _incremental_collection_failed = false; | |
| 246 // The "dilatation_factor" is the expansion that can occur on | |
| 247 // account of the fact that the minimum object size in the CMS | |
| 248 // generation may be larger than that in, say, a contiguous young | |
| 249 // generation. | |
| 250 // Ideally, in the calculation below, we'd compute the dilatation | |
| 251 // factor as: MinChunkSize/(promoting_gen's min object size) | |
| 252 // Since we do not have such a general query interface for the | |
| 253 // promoting generation, we'll instead just use the mimimum | |
| 254 // object size (which today is a header's worth of space); | |
| 255 // note that all arithmetic is in units of HeapWords. | |
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256 assert(MinChunkSize >= CollectedHeap::min_fill_size(), "just checking"); |
| 0 | 257 assert(_dilatation_factor >= 1.0, "from previous assert"); |
| 258 } | |
| 259 | |
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260 |
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261 // The field "_initiating_occupancy" represents the occupancy percentage |
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262 // at which we trigger a new collection cycle. Unless explicitly specified |
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263 // via CMSInitiating[Perm]OccupancyFraction (argument "io" below), it |
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264 // is calculated by: |
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265 // |
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266 // Let "f" be MinHeapFreeRatio in |
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267 // |
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268 // _intiating_occupancy = 100-f + |
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269 // f * (CMSTrigger[Perm]Ratio/100) |
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270 // where CMSTrigger[Perm]Ratio is the argument "tr" below. |
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271 // |
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272 // That is, if we assume the heap is at its desired maximum occupancy at the |
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273 // end of a collection, we let CMSTrigger[Perm]Ratio of the (purported) free |
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274 // space be allocated before initiating a new collection cycle. |
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275 // |
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276 void ConcurrentMarkSweepGeneration::init_initiating_occupancy(intx io, intx tr) { |
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277 assert(io <= 100 && tr >= 0 && tr <= 100, "Check the arguments"); |
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278 if (io >= 0) { |
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279 _initiating_occupancy = (double)io / 100.0; |
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280 } else { |
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281 _initiating_occupancy = ((100 - MinHeapFreeRatio) + |
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282 (double)(tr * MinHeapFreeRatio) / 100.0) |
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283 / 100.0; |
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284 } |
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285 } |
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286 |
| 0 | 287 void ConcurrentMarkSweepGeneration::ref_processor_init() { |
| 288 assert(collector() != NULL, "no collector"); | |
| 289 collector()->ref_processor_init(); | |
| 290 } | |
| 291 | |
| 292 void CMSCollector::ref_processor_init() { | |
| 293 if (_ref_processor == NULL) { | |
| 294 // Allocate and initialize a reference processor | |
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295 _ref_processor = |
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296 new ReferenceProcessor(_span, // span |
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297 (ParallelGCThreads > 1) && ParallelRefProcEnabled, // mt processing |
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298 (int) ParallelGCThreads, // mt processing degree |
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299 _cmsGen->refs_discovery_is_mt(), // mt discovery |
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300 (int) MAX2(ConcGCThreads, ParallelGCThreads), // mt discovery degree |
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301 _cmsGen->refs_discovery_is_atomic(), // discovery is not atomic |
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302 &_is_alive_closure, // closure for liveness info |
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303 false); // next field updates do not need write barrier |
| 0 | 304 // Initialize the _ref_processor field of CMSGen |
| 305 _cmsGen->set_ref_processor(_ref_processor); | |
| 306 | |
| 307 // Allocate a dummy ref processor for perm gen. | |
| 308 ReferenceProcessor* rp2 = new ReferenceProcessor(); | |
| 309 if (rp2 == NULL) { | |
| 310 vm_exit_during_initialization("Could not allocate ReferenceProcessor object"); | |
| 311 } | |
| 312 _permGen->set_ref_processor(rp2); | |
| 313 } | |
| 314 } | |
| 315 | |
| 316 CMSAdaptiveSizePolicy* CMSCollector::size_policy() { | |
| 317 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 318 assert(gch->kind() == CollectedHeap::GenCollectedHeap, | |
| 319 "Wrong type of heap"); | |
| 320 CMSAdaptiveSizePolicy* sp = (CMSAdaptiveSizePolicy*) | |
| 321 gch->gen_policy()->size_policy(); | |
| 322 assert(sp->is_gc_cms_adaptive_size_policy(), | |
| 323 "Wrong type of size policy"); | |
| 324 return sp; | |
| 325 } | |
| 326 | |
| 327 CMSGCAdaptivePolicyCounters* CMSCollector::gc_adaptive_policy_counters() { | |
| 328 CMSGCAdaptivePolicyCounters* results = | |
| 329 (CMSGCAdaptivePolicyCounters*) collector_policy()->counters(); | |
| 330 assert( | |
| 331 results->kind() == GCPolicyCounters::CMSGCAdaptivePolicyCountersKind, | |
| 332 "Wrong gc policy counter kind"); | |
| 333 return results; | |
| 334 } | |
| 335 | |
| 336 | |
| 337 void ConcurrentMarkSweepGeneration::initialize_performance_counters() { | |
| 338 | |
| 339 const char* gen_name = "old"; | |
| 340 | |
| 341 // Generation Counters - generation 1, 1 subspace | |
| 342 _gen_counters = new GenerationCounters(gen_name, 1, 1, &_virtual_space); | |
| 343 | |
| 344 _space_counters = new GSpaceCounters(gen_name, 0, | |
| 345 _virtual_space.reserved_size(), | |
| 346 this, _gen_counters); | |
| 347 } | |
| 348 | |
| 349 CMSStats::CMSStats(ConcurrentMarkSweepGeneration* cms_gen, unsigned int alpha): | |
| 350 _cms_gen(cms_gen) | |
| 351 { | |
| 352 assert(alpha <= 100, "bad value"); | |
| 353 _saved_alpha = alpha; | |
| 354 | |
| 355 // Initialize the alphas to the bootstrap value of 100. | |
| 356 _gc0_alpha = _cms_alpha = 100; | |
| 357 | |
| 358 _cms_begin_time.update(); | |
| 359 _cms_end_time.update(); | |
| 360 | |
| 361 _gc0_duration = 0.0; | |
| 362 _gc0_period = 0.0; | |
| 363 _gc0_promoted = 0; | |
| 364 | |
| 365 _cms_duration = 0.0; | |
| 366 _cms_period = 0.0; | |
| 367 _cms_allocated = 0; | |
| 368 | |
| 369 _cms_used_at_gc0_begin = 0; | |
| 370 _cms_used_at_gc0_end = 0; | |
| 371 _allow_duty_cycle_reduction = false; | |
| 372 _valid_bits = 0; | |
| 373 _icms_duty_cycle = CMSIncrementalDutyCycle; | |
| 374 } | |
| 375 | |
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376 double CMSStats::cms_free_adjustment_factor(size_t free) const { |
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377 // TBD: CR 6909490 |
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378 return 1.0; |
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379 } |
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380 |
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381 void CMSStats::adjust_cms_free_adjustment_factor(bool fail, size_t free) { |
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382 } |
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383 |
| 0 | 384 // If promotion failure handling is on use |
| 385 // the padded average size of the promotion for each | |
| 386 // young generation collection. | |
| 387 double CMSStats::time_until_cms_gen_full() const { | |
| 388 size_t cms_free = _cms_gen->cmsSpace()->free(); | |
| 389 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
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390 size_t expected_promotion = MIN2(gch->get_gen(0)->capacity(), |
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391 (size_t) _cms_gen->gc_stats()->avg_promoted()->padded_average()); |
| 0 | 392 if (cms_free > expected_promotion) { |
| 393 // Start a cms collection if there isn't enough space to promote | |
| 394 // for the next minor collection. Use the padded average as | |
| 395 // a safety factor. | |
| 396 cms_free -= expected_promotion; | |
| 397 | |
| 398 // Adjust by the safety factor. | |
| 399 double cms_free_dbl = (double)cms_free; | |
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400 double cms_adjustment = (100.0 - CMSIncrementalSafetyFactor)/100.0; |
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401 // Apply a further correction factor which tries to adjust |
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402 // for recent occurance of concurrent mode failures. |
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403 cms_adjustment = cms_adjustment * cms_free_adjustment_factor(cms_free); |
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404 cms_free_dbl = cms_free_dbl * cms_adjustment; |
| 0 | 405 |
| 406 if (PrintGCDetails && Verbose) { | |
| 407 gclog_or_tty->print_cr("CMSStats::time_until_cms_gen_full: cms_free " | |
| 408 SIZE_FORMAT " expected_promotion " SIZE_FORMAT, | |
| 409 cms_free, expected_promotion); | |
| 410 gclog_or_tty->print_cr(" cms_free_dbl %f cms_consumption_rate %f", | |
| 411 cms_free_dbl, cms_consumption_rate() + 1.0); | |
| 412 } | |
| 413 // Add 1 in case the consumption rate goes to zero. | |
| 414 return cms_free_dbl / (cms_consumption_rate() + 1.0); | |
| 415 } | |
| 416 return 0.0; | |
| 417 } | |
| 418 | |
| 419 // Compare the duration of the cms collection to the | |
| 420 // time remaining before the cms generation is empty. | |
| 421 // Note that the time from the start of the cms collection | |
| 422 // to the start of the cms sweep (less than the total | |
| 423 // duration of the cms collection) can be used. This | |
| 424 // has been tried and some applications experienced | |
| 425 // promotion failures early in execution. This was | |
| 426 // possibly because the averages were not accurate | |
| 427 // enough at the beginning. | |
| 428 double CMSStats::time_until_cms_start() const { | |
| 429 // We add "gc0_period" to the "work" calculation | |
| 430 // below because this query is done (mostly) at the | |
| 431 // end of a scavenge, so we need to conservatively | |
| 432 // account for that much possible delay | |
| 433 // in the query so as to avoid concurrent mode failures | |
| 434 // due to starting the collection just a wee bit too | |
| 435 // late. | |
| 436 double work = cms_duration() + gc0_period(); | |
| 437 double deadline = time_until_cms_gen_full(); | |
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438 // If a concurrent mode failure occurred recently, we want to be |
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439 // more conservative and halve our expected time_until_cms_gen_full() |
| 0 | 440 if (work > deadline) { |
| 441 if (Verbose && PrintGCDetails) { | |
| 442 gclog_or_tty->print( | |
| 443 " CMSCollector: collect because of anticipated promotion " | |
| 444 "before full %3.7f + %3.7f > %3.7f ", cms_duration(), | |
| 445 gc0_period(), time_until_cms_gen_full()); | |
| 446 } | |
| 447 return 0.0; | |
| 448 } | |
| 449 return work - deadline; | |
| 450 } | |
| 451 | |
| 452 // Return a duty cycle based on old_duty_cycle and new_duty_cycle, limiting the | |
| 453 // amount of change to prevent wild oscillation. | |
| 454 unsigned int CMSStats::icms_damped_duty_cycle(unsigned int old_duty_cycle, | |
| 455 unsigned int new_duty_cycle) { | |
| 456 assert(old_duty_cycle <= 100, "bad input value"); | |
| 457 assert(new_duty_cycle <= 100, "bad input value"); | |
| 458 | |
| 459 // Note: use subtraction with caution since it may underflow (values are | |
| 460 // unsigned). Addition is safe since we're in the range 0-100. | |
| 461 unsigned int damped_duty_cycle = new_duty_cycle; | |
| 462 if (new_duty_cycle < old_duty_cycle) { | |
| 463 const unsigned int largest_delta = MAX2(old_duty_cycle / 4, 5U); | |
| 464 if (new_duty_cycle + largest_delta < old_duty_cycle) { | |
| 465 damped_duty_cycle = old_duty_cycle - largest_delta; | |
| 466 } | |
| 467 } else if (new_duty_cycle > old_duty_cycle) { | |
| 468 const unsigned int largest_delta = MAX2(old_duty_cycle / 4, 15U); | |
| 469 if (new_duty_cycle > old_duty_cycle + largest_delta) { | |
| 470 damped_duty_cycle = MIN2(old_duty_cycle + largest_delta, 100U); | |
| 471 } | |
| 472 } | |
| 473 assert(damped_duty_cycle <= 100, "invalid duty cycle computed"); | |
| 474 | |
| 475 if (CMSTraceIncrementalPacing) { | |
| 476 gclog_or_tty->print(" [icms_damped_duty_cycle(%d,%d) = %d] ", | |
| 477 old_duty_cycle, new_duty_cycle, damped_duty_cycle); | |
| 478 } | |
| 479 return damped_duty_cycle; | |
| 480 } | |
| 481 | |
| 482 unsigned int CMSStats::icms_update_duty_cycle_impl() { | |
| 483 assert(CMSIncrementalPacing && valid(), | |
| 484 "should be handled in icms_update_duty_cycle()"); | |
| 485 | |
| 486 double cms_time_so_far = cms_timer().seconds(); | |
| 487 double scaled_duration = cms_duration_per_mb() * _cms_used_at_gc0_end / M; | |
| 488 double scaled_duration_remaining = fabsd(scaled_duration - cms_time_so_far); | |
| 489 | |
| 490 // Avoid division by 0. | |
| 491 double time_until_full = MAX2(time_until_cms_gen_full(), 0.01); | |
| 492 double duty_cycle_dbl = 100.0 * scaled_duration_remaining / time_until_full; | |
| 493 | |
| 494 unsigned int new_duty_cycle = MIN2((unsigned int)duty_cycle_dbl, 100U); | |
| 495 if (new_duty_cycle > _icms_duty_cycle) { | |
| 496 // Avoid very small duty cycles (1 or 2); 0 is allowed. | |
| 497 if (new_duty_cycle > 2) { | |
| 498 _icms_duty_cycle = icms_damped_duty_cycle(_icms_duty_cycle, | |
| 499 new_duty_cycle); | |
| 500 } | |
| 501 } else if (_allow_duty_cycle_reduction) { | |
| 502 // The duty cycle is reduced only once per cms cycle (see record_cms_end()). | |
| 503 new_duty_cycle = icms_damped_duty_cycle(_icms_duty_cycle, new_duty_cycle); | |
| 504 // Respect the minimum duty cycle. | |
| 505 unsigned int min_duty_cycle = (unsigned int)CMSIncrementalDutyCycleMin; | |
| 506 _icms_duty_cycle = MAX2(new_duty_cycle, min_duty_cycle); | |
| 507 } | |
| 508 | |
| 509 if (PrintGCDetails || CMSTraceIncrementalPacing) { | |
| 510 gclog_or_tty->print(" icms_dc=%d ", _icms_duty_cycle); | |
| 511 } | |
| 512 | |
| 513 _allow_duty_cycle_reduction = false; | |
| 514 return _icms_duty_cycle; | |
| 515 } | |
| 516 | |
| 517 #ifndef PRODUCT | |
| 518 void CMSStats::print_on(outputStream *st) const { | |
| 519 st->print(" gc0_alpha=%d,cms_alpha=%d", _gc0_alpha, _cms_alpha); | |
| 520 st->print(",gc0_dur=%g,gc0_per=%g,gc0_promo=" SIZE_FORMAT, | |
| 521 gc0_duration(), gc0_period(), gc0_promoted()); | |
| 522 st->print(",cms_dur=%g,cms_dur_per_mb=%g,cms_per=%g,cms_alloc=" SIZE_FORMAT, | |
| 523 cms_duration(), cms_duration_per_mb(), | |
| 524 cms_period(), cms_allocated()); | |
| 525 st->print(",cms_since_beg=%g,cms_since_end=%g", | |
| 526 cms_time_since_begin(), cms_time_since_end()); | |
| 527 st->print(",cms_used_beg=" SIZE_FORMAT ",cms_used_end=" SIZE_FORMAT, | |
| 528 _cms_used_at_gc0_begin, _cms_used_at_gc0_end); | |
| 529 if (CMSIncrementalMode) { | |
| 530 st->print(",dc=%d", icms_duty_cycle()); | |
| 531 } | |
| 532 | |
| 533 if (valid()) { | |
| 534 st->print(",promo_rate=%g,cms_alloc_rate=%g", | |
| 535 promotion_rate(), cms_allocation_rate()); | |
| 536 st->print(",cms_consumption_rate=%g,time_until_full=%g", | |
| 537 cms_consumption_rate(), time_until_cms_gen_full()); | |
| 538 } | |
| 539 st->print(" "); | |
| 540 } | |
| 541 #endif // #ifndef PRODUCT | |
| 542 | |
| 543 CMSCollector::CollectorState CMSCollector::_collectorState = | |
| 544 CMSCollector::Idling; | |
| 545 bool CMSCollector::_foregroundGCIsActive = false; | |
| 546 bool CMSCollector::_foregroundGCShouldWait = false; | |
| 547 | |
| 548 CMSCollector::CMSCollector(ConcurrentMarkSweepGeneration* cmsGen, | |
| 549 ConcurrentMarkSweepGeneration* permGen, | |
| 550 CardTableRS* ct, | |
| 551 ConcurrentMarkSweepPolicy* cp): | |
| 552 _cmsGen(cmsGen), | |
| 553 _permGen(permGen), | |
| 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 _perm_gen_verify_bit_map(0, -1 /* no mutex */, "No_lock"), | |
| 562 _modUnionTable((CardTableModRefBS::card_shift - LogHeapWordSize), | |
| 563 -1 /* lock-free */, "No_lock" /* dummy */), | |
| 564 _modUnionClosure(&_modUnionTable), | |
| 565 _modUnionClosurePar(&_modUnionTable), | |
|
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566 // Adjust my span to cover old (cms) gen and perm gen |
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567 _span(cmsGen->reserved()._union(permGen->reserved())), |
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568 // Construct the is_alive_closure with _span & markBitMap |
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569 _is_alive_closure(_span, &_markBitMap), |
| 0 | 570 _restart_addr(NULL), |
| 571 _overflow_list(NULL), | |
| 572 _stats(cmsGen), | |
| 573 _eden_chunk_array(NULL), // may be set in ctor body | |
| 574 _eden_chunk_capacity(0), // -- ditto -- | |
| 575 _eden_chunk_index(0), // -- ditto -- | |
| 576 _survivor_plab_array(NULL), // -- ditto -- | |
| 577 _survivor_chunk_array(NULL), // -- ditto -- | |
| 578 _survivor_chunk_capacity(0), // -- ditto -- | |
| 579 _survivor_chunk_index(0), // -- ditto -- | |
| 580 _ser_pmc_preclean_ovflw(0), | |
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581 _ser_kac_preclean_ovflw(0), |
| 0 | 582 _ser_pmc_remark_ovflw(0), |
| 583 _par_pmc_remark_ovflw(0), | |
| 584 _ser_kac_ovflw(0), | |
| 585 _par_kac_ovflw(0), | |
| 586 #ifndef PRODUCT | |
| 587 _num_par_pushes(0), | |
| 588 #endif | |
| 589 _collection_count_start(0), | |
| 590 _verifying(false), | |
| 591 _icms_start_limit(NULL), | |
| 592 _icms_stop_limit(NULL), | |
| 593 _verification_mark_bm(0, Mutex::leaf + 1, "CMS_verification_mark_bm_lock"), | |
| 594 _completed_initialization(false), | |
| 595 _collector_policy(cp), | |
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596 _should_unload_classes(false), |
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597 _concurrent_cycles_since_last_unload(0), |
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598 _roots_scanning_options(0), |
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599 _inter_sweep_estimate(CMS_SweepWeight, CMS_SweepPadding), |
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600 _intra_sweep_estimate(CMS_SweepWeight, CMS_SweepPadding) |
| 0 | 601 { |
| 602 if (ExplicitGCInvokesConcurrentAndUnloadsClasses) { | |
| 603 ExplicitGCInvokesConcurrent = true; | |
| 604 } | |
| 605 // Now expand the span and allocate the collection support structures | |
| 606 // (MUT, marking bit map etc.) to cover both generations subject to | |
| 607 // collection. | |
| 608 | |
| 609 // First check that _permGen is adjacent to _cmsGen and above it. | |
| 610 assert( _cmsGen->reserved().word_size() > 0 | |
| 611 && _permGen->reserved().word_size() > 0, | |
| 612 "generations should not be of zero size"); | |
| 613 assert(_cmsGen->reserved().intersection(_permGen->reserved()).is_empty(), | |
| 614 "_cmsGen and _permGen should not overlap"); | |
| 615 assert(_cmsGen->reserved().end() == _permGen->reserved().start(), | |
| 616 "_cmsGen->end() different from _permGen->start()"); | |
| 617 | |
| 618 // For use by dirty card to oop closures. | |
| 619 _cmsGen->cmsSpace()->set_collector(this); | |
| 620 _permGen->cmsSpace()->set_collector(this); | |
| 621 | |
| 622 // Allocate MUT and marking bit map | |
| 623 { | |
| 624 MutexLockerEx x(_markBitMap.lock(), Mutex::_no_safepoint_check_flag); | |
| 625 if (!_markBitMap.allocate(_span)) { | |
| 626 warning("Failed to allocate CMS Bit Map"); | |
| 627 return; | |
| 628 } | |
| 629 assert(_markBitMap.covers(_span), "_markBitMap inconsistency?"); | |
| 630 } | |
| 631 { | |
| 632 _modUnionTable.allocate(_span); | |
| 633 assert(_modUnionTable.covers(_span), "_modUnionTable inconsistency?"); | |
| 634 } | |
| 635 | |
| 1284 | 636 if (!_markStack.allocate(MarkStackSize)) { |
| 0 | 637 warning("Failed to allocate CMS Marking Stack"); |
| 638 return; | |
| 639 } | |
| 640 if (!_revisitStack.allocate(CMSRevisitStackSize)) { | |
| 641 warning("Failed to allocate CMS Revisit Stack"); | |
| 642 return; | |
| 643 } | |
| 644 | |
| 645 // Support for multi-threaded concurrent phases | |
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646 if (CMSConcurrentMTEnabled) { |
| 1284 | 647 if (FLAG_IS_DEFAULT(ConcGCThreads)) { |
| 0 | 648 // just for now |
| 1284 | 649 FLAG_SET_DEFAULT(ConcGCThreads, (ParallelGCThreads + 3)/4); |
| 650 } | |
| 651 if (ConcGCThreads > 1) { | |
| 0 | 652 _conc_workers = new YieldingFlexibleWorkGang("Parallel CMS Threads", |
| 1284 | 653 ConcGCThreads, true); |
| 0 | 654 if (_conc_workers == NULL) { |
| 655 warning("GC/CMS: _conc_workers allocation failure: " | |
| 656 "forcing -CMSConcurrentMTEnabled"); | |
| 657 CMSConcurrentMTEnabled = false; | |
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658 } else { |
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659 _conc_workers->initialize_workers(); |
| 0 | 660 } |
| 661 } else { | |
| 662 CMSConcurrentMTEnabled = false; | |
| 663 } | |
| 664 } | |
| 665 if (!CMSConcurrentMTEnabled) { | |
| 1284 | 666 ConcGCThreads = 0; |
| 0 | 667 } else { |
| 668 // Turn off CMSCleanOnEnter optimization temporarily for | |
| 669 // the MT case where it's not fixed yet; see 6178663. | |
| 670 CMSCleanOnEnter = false; | |
| 671 } | |
| 1284 | 672 assert((_conc_workers != NULL) == (ConcGCThreads > 1), |
| 0 | 673 "Inconsistency"); |
| 674 | |
| 675 // Parallel task queues; these are shared for the | |
| 676 // concurrent and stop-world phases of CMS, but | |
| 677 // are not shared with parallel scavenge (ParNew). | |
| 678 { | |
| 679 uint i; | |
| 1284 | 680 uint num_queues = (uint) MAX2(ParallelGCThreads, ConcGCThreads); |
| 0 | 681 |
| 682 if ((CMSParallelRemarkEnabled || CMSConcurrentMTEnabled | |
| 683 || ParallelRefProcEnabled) | |
| 684 && num_queues > 0) { | |
| 685 _task_queues = new OopTaskQueueSet(num_queues); | |
| 686 if (_task_queues == NULL) { | |
| 687 warning("task_queues allocation failure."); | |
| 688 return; | |
| 689 } | |
| 690 _hash_seed = NEW_C_HEAP_ARRAY(int, num_queues); | |
| 691 if (_hash_seed == NULL) { | |
| 692 warning("_hash_seed array allocation failure"); | |
| 693 return; | |
| 694 } | |
| 695 | |
| 1665 | 696 typedef Padded<OopTaskQueue> PaddedOopTaskQueue; |
| 0 | 697 for (i = 0; i < num_queues; i++) { |
| 1665 | 698 PaddedOopTaskQueue *q = new PaddedOopTaskQueue(); |
| 699 if (q == NULL) { | |
| 0 | 700 warning("work_queue allocation failure."); |
| 701 return; | |
| 702 } | |
| 1665 | 703 _task_queues->register_queue(i, q); |
| 0 | 704 } |
| 705 for (i = 0; i < num_queues; i++) { | |
| 706 _task_queues->queue(i)->initialize(); | |
| 707 _hash_seed[i] = 17; // copied from ParNew | |
| 708 } | |
| 709 } | |
| 710 } | |
| 711 | |
|
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712 _cmsGen ->init_initiating_occupancy(CMSInitiatingOccupancyFraction, CMSTriggerRatio); |
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713 _permGen->init_initiating_occupancy(CMSInitiatingPermOccupancyFraction, CMSTriggerPermRatio); |
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714 |
| 0 | 715 // Clip CMSBootstrapOccupancy between 0 and 100. |
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716 _bootstrap_occupancy = ((double)MIN2((uintx)100, MAX2((uintx)0, CMSBootstrapOccupancy))) |
| 0 | 717 /(double)100; |
| 718 | |
| 719 _full_gcs_since_conc_gc = 0; | |
| 720 | |
| 721 // Now tell CMS generations the identity of their collector | |
| 722 ConcurrentMarkSweepGeneration::set_collector(this); | |
| 723 | |
| 724 // Create & start a CMS thread for this CMS collector | |
| 725 _cmsThread = ConcurrentMarkSweepThread::start(this); | |
| 726 assert(cmsThread() != NULL, "CMS Thread should have been created"); | |
| 727 assert(cmsThread()->collector() == this, | |
| 728 "CMS Thread should refer to this gen"); | |
| 729 assert(CGC_lock != NULL, "Where's the CGC_lock?"); | |
| 730 | |
| 731 // Support for parallelizing young gen rescan | |
| 732 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 733 _young_gen = gch->prev_gen(_cmsGen); | |
| 734 if (gch->supports_inline_contig_alloc()) { | |
| 735 _top_addr = gch->top_addr(); | |
| 736 _end_addr = gch->end_addr(); | |
| 737 assert(_young_gen != NULL, "no _young_gen"); | |
| 738 _eden_chunk_index = 0; | |
| 739 _eden_chunk_capacity = (_young_gen->max_capacity()+CMSSamplingGrain)/CMSSamplingGrain; | |
| 740 _eden_chunk_array = NEW_C_HEAP_ARRAY(HeapWord*, _eden_chunk_capacity); | |
| 741 if (_eden_chunk_array == NULL) { | |
| 742 _eden_chunk_capacity = 0; | |
| 743 warning("GC/CMS: _eden_chunk_array allocation failure"); | |
| 744 } | |
| 745 } | |
| 746 assert(_eden_chunk_array != NULL || _eden_chunk_capacity == 0, "Error"); | |
| 747 | |
| 748 // Support for parallelizing survivor space rescan | |
| 749 if (CMSParallelRemarkEnabled && CMSParallelSurvivorRemarkEnabled) { | |
|
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750 const size_t max_plab_samples = |
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751 ((DefNewGeneration*)_young_gen)->max_survivor_size()/MinTLABSize; |
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752 |
| 0 | 753 _survivor_plab_array = NEW_C_HEAP_ARRAY(ChunkArray, ParallelGCThreads); |
| 754 _survivor_chunk_array = NEW_C_HEAP_ARRAY(HeapWord*, 2*max_plab_samples); | |
| 755 _cursor = NEW_C_HEAP_ARRAY(size_t, ParallelGCThreads); | |
| 756 if (_survivor_plab_array == NULL || _survivor_chunk_array == NULL | |
| 757 || _cursor == NULL) { | |
| 758 warning("Failed to allocate survivor plab/chunk array"); | |
| 759 if (_survivor_plab_array != NULL) { | |
| 760 FREE_C_HEAP_ARRAY(ChunkArray, _survivor_plab_array); | |
| 761 _survivor_plab_array = NULL; | |
| 762 } | |
| 763 if (_survivor_chunk_array != NULL) { | |
| 764 FREE_C_HEAP_ARRAY(HeapWord*, _survivor_chunk_array); | |
| 765 _survivor_chunk_array = NULL; | |
| 766 } | |
| 767 if (_cursor != NULL) { | |
| 768 FREE_C_HEAP_ARRAY(size_t, _cursor); | |
| 769 _cursor = NULL; | |
| 770 } | |
| 771 } else { | |
| 772 _survivor_chunk_capacity = 2*max_plab_samples; | |
| 773 for (uint i = 0; i < ParallelGCThreads; i++) { | |
| 774 HeapWord** vec = NEW_C_HEAP_ARRAY(HeapWord*, max_plab_samples); | |
| 775 if (vec == NULL) { | |
| 776 warning("Failed to allocate survivor plab array"); | |
| 777 for (int j = i; j > 0; j--) { | |
| 778 FREE_C_HEAP_ARRAY(HeapWord*, _survivor_plab_array[j-1].array()); | |
| 779 } | |
| 780 FREE_C_HEAP_ARRAY(ChunkArray, _survivor_plab_array); | |
| 781 FREE_C_HEAP_ARRAY(HeapWord*, _survivor_chunk_array); | |
| 782 _survivor_plab_array = NULL; | |
| 783 _survivor_chunk_array = NULL; | |
| 784 _survivor_chunk_capacity = 0; | |
| 785 break; | |
| 786 } else { | |
| 787 ChunkArray* cur = | |
| 788 ::new (&_survivor_plab_array[i]) ChunkArray(vec, | |
| 789 max_plab_samples); | |
| 790 assert(cur->end() == 0, "Should be 0"); | |
| 791 assert(cur->array() == vec, "Should be vec"); | |
| 792 assert(cur->capacity() == max_plab_samples, "Error"); | |
| 793 } | |
| 794 } | |
| 795 } | |
| 796 } | |
| 797 assert( ( _survivor_plab_array != NULL | |
| 798 && _survivor_chunk_array != NULL) | |
| 799 || ( _survivor_chunk_capacity == 0 | |
| 800 && _survivor_chunk_index == 0), | |
| 801 "Error"); | |
| 802 | |
| 803 // Choose what strong roots should be scanned depending on verification options | |
| 804 // and perm gen collection mode. | |
| 805 if (!CMSClassUnloadingEnabled) { | |
| 806 // If class unloading is disabled we want to include all classes into the root set. | |
| 807 add_root_scanning_option(SharedHeap::SO_AllClasses); | |
| 808 } else { | |
| 809 add_root_scanning_option(SharedHeap::SO_SystemClasses); | |
| 810 } | |
| 811 | |
| 812 NOT_PRODUCT(_overflow_counter = CMSMarkStackOverflowInterval;) | |
| 813 _gc_counters = new CollectorCounters("CMS", 1); | |
| 814 _completed_initialization = true; | |
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815 _inter_sweep_timer.start(); // start of time |
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816 #ifdef SPARC |
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817 // Issue a stern warning, but allow use for experimentation and debugging. |
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818 if (VM_Version::is_sun4v() && UseMemSetInBOT) { |
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819 assert(!FLAG_IS_DEFAULT(UseMemSetInBOT), "Error"); |
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820 warning("Experimental flag -XX:+UseMemSetInBOT is known to cause instability" |
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821 " on sun4v; please understand that you are using at your own risk!"); |
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822 } |
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823 #endif |
| 0 | 824 } |
| 825 | |
| 826 const char* ConcurrentMarkSweepGeneration::name() const { | |
| 827 return "concurrent mark-sweep generation"; | |
| 828 } | |
| 829 void ConcurrentMarkSweepGeneration::update_counters() { | |
| 830 if (UsePerfData) { | |
| 831 _space_counters->update_all(); | |
| 832 _gen_counters->update_all(); | |
| 833 } | |
| 834 } | |
| 835 | |
| 836 // this is an optimized version of update_counters(). it takes the | |
| 837 // used value as a parameter rather than computing it. | |
| 838 // | |
| 839 void ConcurrentMarkSweepGeneration::update_counters(size_t used) { | |
| 840 if (UsePerfData) { | |
| 841 _space_counters->update_used(used); | |
| 842 _space_counters->update_capacity(); | |
| 843 _gen_counters->update_all(); | |
| 844 } | |
| 845 } | |
| 846 | |
| 847 void ConcurrentMarkSweepGeneration::print() const { | |
| 848 Generation::print(); | |
| 849 cmsSpace()->print(); | |
| 850 } | |
| 851 | |
| 852 #ifndef PRODUCT | |
| 853 void ConcurrentMarkSweepGeneration::print_statistics() { | |
| 854 cmsSpace()->printFLCensus(0); | |
| 855 } | |
| 856 #endif | |
| 857 | |
| 858 void ConcurrentMarkSweepGeneration::printOccupancy(const char *s) { | |
| 859 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 860 if (PrintGCDetails) { | |
| 861 if (Verbose) { | |
| 862 gclog_or_tty->print(" [%d %s-%s: "SIZE_FORMAT"("SIZE_FORMAT")]", | |
| 863 level(), short_name(), s, used(), capacity()); | |
| 864 } else { | |
| 865 gclog_or_tty->print(" [%d %s-%s: "SIZE_FORMAT"K("SIZE_FORMAT"K)]", | |
| 866 level(), short_name(), s, used() / K, capacity() / K); | |
| 867 } | |
| 868 } | |
| 869 if (Verbose) { | |
| 870 gclog_or_tty->print(" "SIZE_FORMAT"("SIZE_FORMAT")", | |
| 871 gch->used(), gch->capacity()); | |
| 872 } else { | |
| 873 gclog_or_tty->print(" "SIZE_FORMAT"K("SIZE_FORMAT"K)", | |
| 874 gch->used() / K, gch->capacity() / K); | |
| 875 } | |
| 876 } | |
| 877 | |
| 878 size_t | |
| 879 ConcurrentMarkSweepGeneration::contiguous_available() const { | |
| 880 // dld proposes an improvement in precision here. If the committed | |
| 881 // part of the space ends in a free block we should add that to | |
| 882 // uncommitted size in the calculation below. Will make this | |
| 883 // change later, staying with the approximation below for the | |
| 884 // time being. -- ysr. | |
| 885 return MAX2(_virtual_space.uncommitted_size(), unsafe_max_alloc_nogc()); | |
| 886 } | |
| 887 | |
| 888 size_t | |
| 889 ConcurrentMarkSweepGeneration::unsafe_max_alloc_nogc() const { | |
| 890 return _cmsSpace->max_alloc_in_words() * HeapWordSize; | |
| 891 } | |
| 892 | |
| 893 size_t ConcurrentMarkSweepGeneration::max_available() const { | |
| 894 return free() + _virtual_space.uncommitted_size(); | |
| 895 } | |
| 896 | |
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897 bool ConcurrentMarkSweepGeneration::promotion_attempt_is_safe(size_t max_promotion_in_bytes) const { |
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898 size_t available = max_available(); |
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899 size_t av_promo = (size_t)gc_stats()->avg_promoted()->padded_average(); |
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900 bool res = (available >= av_promo) || (available >= max_promotion_in_bytes); |
|
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901 if (Verbose && PrintGCDetails) { |
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902 gclog_or_tty->print_cr( |
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903 "CMS: promo attempt is%s safe: available("SIZE_FORMAT") %s av_promo("SIZE_FORMAT")," |
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904 "max_promo("SIZE_FORMAT")", |
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905 res? "":" not", available, res? ">=":"<", |
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906 av_promo, max_promotion_in_bytes); |
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907 } |
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908 return res; |
| 0 | 909 } |
| 910 | |
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911 // At a promotion failure dump information on block layout in heap |
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912 // (cms old generation). |
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913 void ConcurrentMarkSweepGeneration::promotion_failure_occurred() { |
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914 if (CMSDumpAtPromotionFailure) { |
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915 cmsSpace()->dump_at_safepoint_with_locks(collector(), gclog_or_tty); |
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916 } |
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917 } |
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918 |
| 0 | 919 CompactibleSpace* |
| 920 ConcurrentMarkSweepGeneration::first_compaction_space() const { | |
| 921 return _cmsSpace; | |
| 922 } | |
| 923 | |
| 924 void ConcurrentMarkSweepGeneration::reset_after_compaction() { | |
| 925 // Clear the promotion information. These pointers can be adjusted | |
| 926 // along with all the other pointers into the heap but | |
| 927 // compaction is expected to be a rare event with | |
| 928 // a heap using cms so don't do it without seeing the need. | |
|
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929 if (CollectedHeap::use_parallel_gc_threads()) { |
| 0 | 930 for (uint i = 0; i < ParallelGCThreads; i++) { |
| 931 _par_gc_thread_states[i]->promo.reset(); | |
| 932 } | |
| 933 } | |
| 934 } | |
| 935 | |
| 936 void ConcurrentMarkSweepGeneration::space_iterate(SpaceClosure* blk, bool usedOnly) { | |
| 937 blk->do_space(_cmsSpace); | |
| 938 } | |
| 939 | |
| 940 void ConcurrentMarkSweepGeneration::compute_new_size() { | |
| 941 assert_locked_or_safepoint(Heap_lock); | |
| 942 | |
| 943 // If incremental collection failed, we just want to expand | |
| 944 // to the limit. | |
| 945 if (incremental_collection_failed()) { | |
| 946 clear_incremental_collection_failed(); | |
| 947 grow_to_reserved(); | |
| 948 return; | |
| 949 } | |
| 950 | |
| 951 size_t expand_bytes = 0; | |
| 952 double free_percentage = ((double) free()) / capacity(); | |
| 953 double desired_free_percentage = (double) MinHeapFreeRatio / 100; | |
| 954 double maximum_free_percentage = (double) MaxHeapFreeRatio / 100; | |
| 955 | |
| 956 // compute expansion delta needed for reaching desired free percentage | |
| 957 if (free_percentage < desired_free_percentage) { | |
| 958 size_t desired_capacity = (size_t)(used() / ((double) 1 - desired_free_percentage)); | |
| 959 assert(desired_capacity >= capacity(), "invalid expansion size"); | |
| 960 expand_bytes = MAX2(desired_capacity - capacity(), MinHeapDeltaBytes); | |
| 961 } | |
| 962 if (expand_bytes > 0) { | |
| 963 if (PrintGCDetails && Verbose) { | |
| 964 size_t desired_capacity = (size_t)(used() / ((double) 1 - desired_free_percentage)); | |
| 965 gclog_or_tty->print_cr("\nFrom compute_new_size: "); | |
| 966 gclog_or_tty->print_cr(" Free fraction %f", free_percentage); | |
| 967 gclog_or_tty->print_cr(" Desired free fraction %f", | |
| 968 desired_free_percentage); | |
| 969 gclog_or_tty->print_cr(" Maximum free fraction %f", | |
| 970 maximum_free_percentage); | |
| 971 gclog_or_tty->print_cr(" Capactiy "SIZE_FORMAT, capacity()/1000); | |
| 972 gclog_or_tty->print_cr(" Desired capacity "SIZE_FORMAT, | |
| 973 desired_capacity/1000); | |
| 974 int prev_level = level() - 1; | |
| 975 if (prev_level >= 0) { | |
| 976 size_t prev_size = 0; | |
| 977 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 978 Generation* prev_gen = gch->_gens[prev_level]; | |
| 979 prev_size = prev_gen->capacity(); | |
| 980 gclog_or_tty->print_cr(" Younger gen size "SIZE_FORMAT, | |
| 981 prev_size/1000); | |
| 982 } | |
| 983 gclog_or_tty->print_cr(" unsafe_max_alloc_nogc "SIZE_FORMAT, | |
| 984 unsafe_max_alloc_nogc()/1000); | |
| 985 gclog_or_tty->print_cr(" contiguous available "SIZE_FORMAT, | |
| 986 contiguous_available()/1000); | |
| 987 gclog_or_tty->print_cr(" Expand by "SIZE_FORMAT" (bytes)", | |
| 988 expand_bytes); | |
| 989 } | |
| 990 // safe if expansion fails | |
| 991 expand(expand_bytes, 0, CMSExpansionCause::_satisfy_free_ratio); | |
| 992 if (PrintGCDetails && Verbose) { | |
| 993 gclog_or_tty->print_cr(" Expanded free fraction %f", | |
| 994 ((double) free()) / capacity()); | |
| 995 } | |
| 996 } | |
| 997 } | |
| 998 | |
| 999 Mutex* ConcurrentMarkSweepGeneration::freelistLock() const { | |
| 1000 return cmsSpace()->freelistLock(); | |
| 1001 } | |
| 1002 | |
| 1003 HeapWord* ConcurrentMarkSweepGeneration::allocate(size_t size, | |
| 1004 bool tlab) { | |
| 1005 CMSSynchronousYieldRequest yr; | |
| 1006 MutexLockerEx x(freelistLock(), | |
| 1007 Mutex::_no_safepoint_check_flag); | |
| 1008 return have_lock_and_allocate(size, tlab); | |
| 1009 } | |
| 1010 | |
| 1011 HeapWord* ConcurrentMarkSweepGeneration::have_lock_and_allocate(size_t size, | |
|
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1012 bool tlab /* ignored */) { |
| 0 | 1013 assert_lock_strong(freelistLock()); |
| 1014 size_t adjustedSize = CompactibleFreeListSpace::adjustObjectSize(size); | |
| 1015 HeapWord* res = cmsSpace()->allocate(adjustedSize); | |
| 1016 // Allocate the object live (grey) if the background collector has | |
| 1017 // started marking. This is necessary because the marker may | |
| 1018 // have passed this address and consequently this object will | |
| 1019 // not otherwise be greyed and would be incorrectly swept up. | |
| 1020 // Note that if this object contains references, the writing | |
| 1021 // of those references will dirty the card containing this object | |
| 1022 // allowing the object to be blackened (and its references scanned) | |
| 1023 // either during a preclean phase or at the final checkpoint. | |
| 1024 if (res != NULL) { | |
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1025 // We may block here with an uninitialized object with |
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1026 // its mark-bit or P-bits not yet set. Such objects need |
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1027 // to be safely navigable by block_start(). |
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1028 assert(oop(res)->klass_or_null() == NULL, "Object should be uninitialized here."); |
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1029 assert(!((FreeChunk*)res)->isFree(), "Error, block will look free but show wrong size"); |
| 0 | 1030 collector()->direct_allocated(res, adjustedSize); |
| 1031 _direct_allocated_words += adjustedSize; | |
| 1032 // allocation counters | |
| 1033 NOT_PRODUCT( | |
| 1034 _numObjectsAllocated++; | |
| 1035 _numWordsAllocated += (int)adjustedSize; | |
| 1036 ) | |
| 1037 } | |
| 1038 return res; | |
| 1039 } | |
| 1040 | |
| 1041 // In the case of direct allocation by mutators in a generation that | |
| 1042 // is being concurrently collected, the object must be allocated | |
| 1043 // live (grey) if the background collector has started marking. | |
| 1044 // This is necessary because the marker may | |
| 1045 // have passed this address and consequently this object will | |
| 1046 // not otherwise be greyed and would be incorrectly swept up. | |
| 1047 // Note that if this object contains references, the writing | |
| 1048 // of those references will dirty the card containing this object | |
| 1049 // allowing the object to be blackened (and its references scanned) | |
| 1050 // either during a preclean phase or at the final checkpoint. | |
| 1051 void CMSCollector::direct_allocated(HeapWord* start, size_t size) { | |
| 1052 assert(_markBitMap.covers(start, size), "Out of bounds"); | |
| 1053 if (_collectorState >= Marking) { | |
| 1054 MutexLockerEx y(_markBitMap.lock(), | |
| 1055 Mutex::_no_safepoint_check_flag); | |
| 1056 // [see comments preceding SweepClosure::do_blk() below for details] | |
| 1057 // 1. need to mark the object as live so it isn't collected | |
| 1058 // 2. need to mark the 2nd bit to indicate the object may be uninitialized | |
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1059 // 3. need to mark the end of the object so marking, precleaning or sweeping |
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1060 // can skip over uninitialized or unparsable objects. An allocated |
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1061 // object is considered uninitialized for our purposes as long as |
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1062 // its klass word is NULL. (Unparsable objects are those which are |
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1063 // initialized in the sense just described, but whose sizes can still |
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1064 // not be correctly determined. Note that the class of unparsable objects |
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1065 // can only occur in the perm gen. All old gen objects are parsable |
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1066 // as soon as they are initialized.) |
| 0 | 1067 _markBitMap.mark(start); // object is live |
| 1068 _markBitMap.mark(start + 1); // object is potentially uninitialized? | |
| 1069 _markBitMap.mark(start + size - 1); | |
| 1070 // mark end of object | |
| 1071 } | |
| 1072 // check that oop looks uninitialized | |
| 187 | 1073 assert(oop(start)->klass_or_null() == NULL, "_klass should be NULL"); |
| 0 | 1074 } |
| 1075 | |
| 1076 void CMSCollector::promoted(bool par, HeapWord* start, | |
| 1077 bool is_obj_array, size_t obj_size) { | |
| 1078 assert(_markBitMap.covers(start), "Out of bounds"); | |
| 1079 // See comment in direct_allocated() about when objects should | |
| 1080 // be allocated live. | |
| 1081 if (_collectorState >= Marking) { | |
| 1082 // we already hold the marking bit map lock, taken in | |
| 1083 // the prologue | |
| 1084 if (par) { | |
| 1085 _markBitMap.par_mark(start); | |
| 1086 } else { | |
| 1087 _markBitMap.mark(start); | |
| 1088 } | |
| 1089 // We don't need to mark the object as uninitialized (as | |
| 1090 // in direct_allocated above) because this is being done with the | |
| 1091 // world stopped and the object will be initialized by the | |
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1092 // time the marking, precleaning or sweeping get to look at it. |
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1093 // But see the code for copying objects into the CMS generation, |
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1094 // where we need to ensure that concurrent readers of the |
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1095 // block offset table are able to safely navigate a block that |
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1096 // is in flux from being free to being allocated (and in |
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1097 // transition while being copied into) and subsequently |
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1098 // becoming a bona-fide object when the copy/promotion is complete. |
| 0 | 1099 assert(SafepointSynchronize::is_at_safepoint(), |
| 1100 "expect promotion only at safepoints"); | |
| 1101 | |
| 1102 if (_collectorState < Sweeping) { | |
| 1103 // Mark the appropriate cards in the modUnionTable, so that | |
| 1104 // this object gets scanned before the sweep. If this is | |
| 1105 // not done, CMS generation references in the object might | |
| 1106 // not get marked. | |
| 1107 // For the case of arrays, which are otherwise precisely | |
| 1108 // marked, we need to dirty the entire array, not just its head. | |
| 1109 if (is_obj_array) { | |
| 1110 // The [par_]mark_range() method expects mr.end() below to | |
| 1111 // be aligned to the granularity of a bit's representation | |
| 1112 // in the heap. In the case of the MUT below, that's a | |
| 1113 // card size. | |
| 1114 MemRegion mr(start, | |
| 1115 (HeapWord*)round_to((intptr_t)(start + obj_size), | |
| 1116 CardTableModRefBS::card_size /* bytes */)); | |
| 1117 if (par) { | |
| 1118 _modUnionTable.par_mark_range(mr); | |
| 1119 } else { | |
| 1120 _modUnionTable.mark_range(mr); | |
| 1121 } | |
| 1122 } else { // not an obj array; we can just mark the head | |
| 1123 if (par) { | |
| 1124 _modUnionTable.par_mark(start); | |
| 1125 } else { | |
| 1126 _modUnionTable.mark(start); | |
| 1127 } | |
| 1128 } | |
| 1129 } | |
| 1130 } | |
| 1131 } | |
| 1132 | |
| 1133 static inline size_t percent_of_space(Space* space, HeapWord* addr) | |
| 1134 { | |
| 1135 size_t delta = pointer_delta(addr, space->bottom()); | |
| 1136 return (size_t)(delta * 100.0 / (space->capacity() / HeapWordSize)); | |
| 1137 } | |
| 1138 | |
| 1139 void CMSCollector::icms_update_allocation_limits() | |
| 1140 { | |
| 1141 Generation* gen0 = GenCollectedHeap::heap()->get_gen(0); | |
| 1142 EdenSpace* eden = gen0->as_DefNewGeneration()->eden(); | |
| 1143 | |
| 1144 const unsigned int duty_cycle = stats().icms_update_duty_cycle(); | |
| 1145 if (CMSTraceIncrementalPacing) { | |
| 1146 stats().print(); | |
| 1147 } | |
| 1148 | |
| 1149 assert(duty_cycle <= 100, "invalid duty cycle"); | |
| 1150 if (duty_cycle != 0) { | |
| 1151 // The duty_cycle is a percentage between 0 and 100; convert to words and | |
| 1152 // then compute the offset from the endpoints of the space. | |
| 1153 size_t free_words = eden->free() / HeapWordSize; | |
| 1154 double free_words_dbl = (double)free_words; | |
| 1155 size_t duty_cycle_words = (size_t)(free_words_dbl * duty_cycle / 100.0); | |
| 1156 size_t offset_words = (free_words - duty_cycle_words) / 2; | |
| 1157 | |
| 1158 _icms_start_limit = eden->top() + offset_words; | |
| 1159 _icms_stop_limit = eden->end() - offset_words; | |
| 1160 | |
| 1161 // The limits may be adjusted (shifted to the right) by | |
| 1162 // CMSIncrementalOffset, to allow the application more mutator time after a | |
| 1163 // young gen gc (when all mutators were stopped) and before CMS starts and | |
| 1164 // takes away one or more cpus. | |
| 1165 if (CMSIncrementalOffset != 0) { | |
| 1166 double adjustment_dbl = free_words_dbl * CMSIncrementalOffset / 100.0; | |
| 1167 size_t adjustment = (size_t)adjustment_dbl; | |
| 1168 HeapWord* tmp_stop = _icms_stop_limit + adjustment; | |
| 1169 if (tmp_stop > _icms_stop_limit && tmp_stop < eden->end()) { | |
| 1170 _icms_start_limit += adjustment; | |
| 1171 _icms_stop_limit = tmp_stop; | |
| 1172 } | |
| 1173 } | |
| 1174 } | |
| 1175 if (duty_cycle == 0 || (_icms_start_limit == _icms_stop_limit)) { | |
| 1176 _icms_start_limit = _icms_stop_limit = eden->end(); | |
| 1177 } | |
| 1178 | |
| 1179 // Install the new start limit. | |
| 1180 eden->set_soft_end(_icms_start_limit); | |
| 1181 | |
| 1182 if (CMSTraceIncrementalMode) { | |
| 1183 gclog_or_tty->print(" icms alloc limits: " | |
| 1184 PTR_FORMAT "," PTR_FORMAT | |
| 1185 " (" SIZE_FORMAT "%%," SIZE_FORMAT "%%) ", | |
| 1186 _icms_start_limit, _icms_stop_limit, | |
| 1187 percent_of_space(eden, _icms_start_limit), | |
| 1188 percent_of_space(eden, _icms_stop_limit)); | |
| 1189 if (Verbose) { | |
| 1190 gclog_or_tty->print("eden: "); | |
| 1191 eden->print_on(gclog_or_tty); | |
| 1192 } | |
| 1193 } | |
| 1194 } | |
| 1195 | |
| 1196 // Any changes here should try to maintain the invariant | |
| 1197 // that if this method is called with _icms_start_limit | |
| 1198 // and _icms_stop_limit both NULL, then it should return NULL | |
| 1199 // and not notify the icms thread. | |
| 1200 HeapWord* | |
| 1201 CMSCollector::allocation_limit_reached(Space* space, HeapWord* top, | |
| 1202 size_t word_size) | |
| 1203 { | |
| 1204 // A start_limit equal to end() means the duty cycle is 0, so treat that as a | |
| 1205 // nop. | |
| 1206 if (CMSIncrementalMode && _icms_start_limit != space->end()) { | |
| 1207 if (top <= _icms_start_limit) { | |
| 1208 if (CMSTraceIncrementalMode) { | |
| 1209 space->print_on(gclog_or_tty); | |
| 1210 gclog_or_tty->stamp(); | |
| 1211 gclog_or_tty->print_cr(" start limit top=" PTR_FORMAT | |
| 1212 ", new limit=" PTR_FORMAT | |
| 1213 " (" SIZE_FORMAT "%%)", | |
| 1214 top, _icms_stop_limit, | |
| 1215 percent_of_space(space, _icms_stop_limit)); | |
| 1216 } | |
| 1217 ConcurrentMarkSweepThread::start_icms(); | |
| 1218 assert(top < _icms_stop_limit, "Tautology"); | |
| 1219 if (word_size < pointer_delta(_icms_stop_limit, top)) { | |
| 1220 return _icms_stop_limit; | |
| 1221 } | |
| 1222 | |
| 1223 // The allocation will cross both the _start and _stop limits, so do the | |
| 1224 // stop notification also and return end(). | |
| 1225 if (CMSTraceIncrementalMode) { | |
| 1226 space->print_on(gclog_or_tty); | |
| 1227 gclog_or_tty->stamp(); | |
| 1228 gclog_or_tty->print_cr(" +stop limit top=" PTR_FORMAT | |
| 1229 ", new limit=" PTR_FORMAT | |
| 1230 " (" SIZE_FORMAT "%%)", | |
| 1231 top, space->end(), | |
| 1232 percent_of_space(space, space->end())); | |
| 1233 } | |
| 1234 ConcurrentMarkSweepThread::stop_icms(); | |
| 1235 return space->end(); | |
| 1236 } | |
| 1237 | |
| 1238 if (top <= _icms_stop_limit) { | |
| 1239 if (CMSTraceIncrementalMode) { | |
| 1240 space->print_on(gclog_or_tty); | |
| 1241 gclog_or_tty->stamp(); | |
| 1242 gclog_or_tty->print_cr(" stop limit top=" PTR_FORMAT | |
| 1243 ", new limit=" PTR_FORMAT | |
| 1244 " (" SIZE_FORMAT "%%)", | |
| 1245 top, space->end(), | |
| 1246 percent_of_space(space, space->end())); | |
| 1247 } | |
| 1248 ConcurrentMarkSweepThread::stop_icms(); | |
| 1249 return space->end(); | |
| 1250 } | |
| 1251 | |
| 1252 if (CMSTraceIncrementalMode) { | |
| 1253 space->print_on(gclog_or_tty); | |
| 1254 gclog_or_tty->stamp(); | |
| 1255 gclog_or_tty->print_cr(" end limit top=" PTR_FORMAT | |
| 1256 ", new limit=" PTR_FORMAT, | |
| 1257 top, NULL); | |
| 1258 } | |
| 1259 } | |
| 1260 | |
| 1261 return NULL; | |
| 1262 } | |
| 1263 | |
|
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1264 oop ConcurrentMarkSweepGeneration::promote(oop obj, size_t obj_size) { |
| 0 | 1265 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in"); |
| 1266 // allocate, copy and if necessary update promoinfo -- | |
| 1267 // delegate to underlying space. | |
| 1268 assert_lock_strong(freelistLock()); | |
| 1269 | |
| 1270 #ifndef PRODUCT | |
| 1271 if (Universe::heap()->promotion_should_fail()) { | |
| 1272 return NULL; | |
| 1273 } | |
| 1274 #endif // #ifndef PRODUCT | |
| 1275 | |
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1276 oop res = _cmsSpace->promote(obj, obj_size); |
| 0 | 1277 if (res == NULL) { |
| 1278 // expand and retry | |
| 1279 size_t s = _cmsSpace->expansionSpaceRequired(obj_size); // HeapWords | |
| 1280 expand(s*HeapWordSize, MinHeapDeltaBytes, | |
| 1281 CMSExpansionCause::_satisfy_promotion); | |
| 1282 // Since there's currently no next generation, we don't try to promote | |
| 1283 // into a more senior generation. | |
| 1284 assert(next_gen() == NULL, "assumption, based upon which no attempt " | |
| 1285 "is made to pass on a possibly failing " | |
| 1286 "promotion to next generation"); | |
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1287 res = _cmsSpace->promote(obj, obj_size); |
| 0 | 1288 } |
| 1289 if (res != NULL) { | |
| 1290 // See comment in allocate() about when objects should | |
| 1291 // be allocated live. | |
| 1292 assert(obj->is_oop(), "Will dereference klass pointer below"); | |
| 1293 collector()->promoted(false, // Not parallel | |
| 1294 (HeapWord*)res, obj->is_objArray(), obj_size); | |
| 1295 // promotion counters | |
| 1296 NOT_PRODUCT( | |
| 1297 _numObjectsPromoted++; | |
| 1298 _numWordsPromoted += | |
| 1299 (int)(CompactibleFreeListSpace::adjustObjectSize(obj->size())); | |
| 1300 ) | |
| 1301 } | |
| 1302 return res; | |
| 1303 } | |
| 1304 | |
| 1305 | |
| 1306 HeapWord* | |
| 1307 ConcurrentMarkSweepGeneration::allocation_limit_reached(Space* space, | |
| 1308 HeapWord* top, | |
| 1309 size_t word_sz) | |
| 1310 { | |
| 1311 return collector()->allocation_limit_reached(space, top, word_sz); | |
| 1312 } | |
| 1313 | |
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1314 // IMPORTANT: Notes on object size recognition in CMS. |
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1315 // --------------------------------------------------- |
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1316 // A block of storage in the CMS generation is always in |
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1317 // one of three states. A free block (FREE), an allocated |
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1318 // object (OBJECT) whose size() method reports the correct size, |
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1319 // and an intermediate state (TRANSIENT) in which its size cannot |
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1320 // be accurately determined. |
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1321 // STATE IDENTIFICATION: (32 bit and 64 bit w/o COOPS) |
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1322 // ----------------------------------------------------- |
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1323 // FREE: klass_word & 1 == 1; mark_word holds block size |
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1324 // |
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1325 // OBJECT: klass_word installed; klass_word != 0 && klass_word & 1 == 0; |
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1326 // obj->size() computes correct size |
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1327 // [Perm Gen objects needs to be "parsable" before they can be navigated] |
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1328 // |
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1329 // TRANSIENT: klass_word == 0; size is indeterminate until we become an OBJECT |
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1330 // |
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1331 // STATE IDENTIFICATION: (64 bit+COOPS) |
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1332 // ------------------------------------ |
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1333 // FREE: mark_word & CMS_FREE_BIT == 1; mark_word & ~CMS_FREE_BIT gives block_size |
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1334 // |
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1335 // OBJECT: klass_word installed; klass_word != 0; |
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1336 // obj->size() computes correct size |
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1337 // [Perm Gen comment above continues to hold] |
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1338 // |
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1339 // TRANSIENT: klass_word == 0; size is indeterminate until we become an OBJECT |
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1340 // |
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1341 // |
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1342 // STATE TRANSITION DIAGRAM |
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1343 // |
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1344 // mut / parnew mut / parnew |
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1345 // FREE --------------------> TRANSIENT ---------------------> OBJECT --| |
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1346 // ^ | |
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1347 // |------------------------ DEAD <------------------------------------| |
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1348 // sweep mut |
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1349 // |
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1350 // While a block is in TRANSIENT state its size cannot be determined |
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1351 // so readers will either need to come back later or stall until |
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1352 // the size can be determined. Note that for the case of direct |
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1353 // allocation, P-bits, when available, may be used to determine the |
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1354 // size of an object that may not yet have been initialized. |
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1355 |
| 0 | 1356 // Things to support parallel young-gen collection. |
| 1357 oop | |
| 1358 ConcurrentMarkSweepGeneration::par_promote(int thread_num, | |
| 1359 oop old, markOop m, | |
| 1360 size_t word_sz) { | |
| 1361 #ifndef PRODUCT | |
| 1362 if (Universe::heap()->promotion_should_fail()) { | |
| 1363 return NULL; | |
| 1364 } | |
| 1365 #endif // #ifndef PRODUCT | |
| 1366 | |
| 1367 CMSParGCThreadState* ps = _par_gc_thread_states[thread_num]; | |
| 1368 PromotionInfo* promoInfo = &ps->promo; | |
| 1369 // if we are tracking promotions, then first ensure space for | |
| 1370 // promotion (including spooling space for saving header if necessary). | |
| 1371 // then allocate and copy, then track promoted info if needed. | |
| 1372 // When tracking (see PromotionInfo::track()), the mark word may | |
| 1373 // be displaced and in this case restoration of the mark word | |
| 1374 // occurs in the (oop_since_save_marks_)iterate phase. | |
| 1375 if (promoInfo->tracking() && !promoInfo->ensure_spooling_space()) { | |
| 1376 // Out of space for allocating spooling buffers; | |
| 1377 // try expanding and allocating spooling buffers. | |
| 1378 if (!expand_and_ensure_spooling_space(promoInfo)) { | |
| 1379 return NULL; | |
| 1380 } | |
| 1381 } | |
| 1382 assert(promoInfo->has_spooling_space(), "Control point invariant"); | |
|
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1383 const size_t alloc_sz = CompactibleFreeListSpace::adjustObjectSize(word_sz); |
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1384 HeapWord* obj_ptr = ps->lab.alloc(alloc_sz); |
| 0 | 1385 if (obj_ptr == NULL) { |
|
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1386 obj_ptr = expand_and_par_lab_allocate(ps, alloc_sz); |
| 0 | 1387 if (obj_ptr == NULL) { |
| 1388 return NULL; | |
| 1389 } | |
| 1390 } | |
| 1391 oop obj = oop(obj_ptr); | |
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1392 OrderAccess::storestore(); |
| 187 | 1393 assert(obj->klass_or_null() == NULL, "Object should be uninitialized here."); |
|
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1394 assert(!((FreeChunk*)obj_ptr)->isFree(), "Error, block will look free but show wrong size"); |
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1395 // IMPORTANT: See note on object initialization for CMS above. |
| 0 | 1396 // Otherwise, copy the object. Here we must be careful to insert the |
| 1397 // klass pointer last, since this marks the block as an allocated object. | |
| 187 | 1398 // Except with compressed oops it's the mark word. |
| 0 | 1399 HeapWord* old_ptr = (HeapWord*)old; |
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1400 // Restore the mark word copied above. |
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1401 obj->set_mark(m); |
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1402 assert(obj->klass_or_null() == NULL, "Object should be uninitialized here."); |
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1403 assert(!((FreeChunk*)obj_ptr)->isFree(), "Error, block will look free but show wrong size"); |
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1404 OrderAccess::storestore(); |
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1405 |
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1406 if (UseCompressedOops) { |
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1407 // Copy gap missed by (aligned) header size calculation below |
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1408 obj->set_klass_gap(old->klass_gap()); |
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1409 } |
| 0 | 1410 if (word_sz > (size_t)oopDesc::header_size()) { |
| 1411 Copy::aligned_disjoint_words(old_ptr + oopDesc::header_size(), | |
| 1412 obj_ptr + oopDesc::header_size(), | |
| 1413 word_sz - oopDesc::header_size()); | |
| 1414 } | |
| 187 | 1415 |
| 0 | 1416 // Now we can track the promoted object, if necessary. We take care |
| 1521 | 1417 // to delay the transition from uninitialized to full object |
| 0 | 1418 // (i.e., insertion of klass pointer) until after, so that it |
| 1419 // atomically becomes a promoted object. | |
| 1420 if (promoInfo->tracking()) { | |
| 1421 promoInfo->track((PromotedObject*)obj, old->klass()); | |
| 1422 } | |
|
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1423 assert(obj->klass_or_null() == NULL, "Object should be uninitialized here."); |
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1424 assert(!((FreeChunk*)obj_ptr)->isFree(), "Error, block will look free but show wrong size"); |
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1425 assert(old->is_oop(), "Will use and dereference old klass ptr below"); |
| 187 | 1426 |
| 1427 // Finally, install the klass pointer (this should be volatile). | |
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1428 OrderAccess::storestore(); |
| 0 | 1429 obj->set_klass(old->klass()); |
|
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1430 // We should now be able to calculate the right size for this object |
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1431 assert(obj->is_oop() && obj->size() == (int)word_sz, "Error, incorrect size computed for promoted object"); |
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1432 |
| 0 | 1433 collector()->promoted(true, // parallel |
| 1434 obj_ptr, old->is_objArray(), word_sz); | |
| 1435 | |
| 1436 NOT_PRODUCT( | |
|
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1437 Atomic::inc_ptr(&_numObjectsPromoted); |
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1438 Atomic::add_ptr(alloc_sz, &_numWordsPromoted); |
| 0 | 1439 ) |
| 1440 | |
| 1441 return obj; | |
| 1442 } | |
| 1443 | |
| 1444 void | |
| 1445 ConcurrentMarkSweepGeneration:: | |
| 1446 par_promote_alloc_undo(int thread_num, | |
| 1447 HeapWord* obj, size_t word_sz) { | |
| 1448 // CMS does not support promotion undo. | |
| 1449 ShouldNotReachHere(); | |
| 1450 } | |
| 1451 | |
| 1452 void | |
| 1453 ConcurrentMarkSweepGeneration:: | |
| 1454 par_promote_alloc_done(int thread_num) { | |
| 1455 CMSParGCThreadState* ps = _par_gc_thread_states[thread_num]; | |
|
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1456 ps->lab.retire(thread_num); |
| 0 | 1457 } |
| 1458 | |
| 1459 void | |
| 1460 ConcurrentMarkSweepGeneration:: | |
| 1461 par_oop_since_save_marks_iterate_done(int thread_num) { | |
| 1462 CMSParGCThreadState* ps = _par_gc_thread_states[thread_num]; | |
| 1463 ParScanWithoutBarrierClosure* dummy_cl = NULL; | |
| 1464 ps->promo.promoted_oops_iterate_nv(dummy_cl); | |
| 1465 } | |
| 1466 | |
| 1467 // XXXPERM | |
| 1468 bool ConcurrentMarkSweepGeneration::should_collect(bool full, | |
| 1469 size_t size, | |
| 1470 bool tlab) | |
| 1471 { | |
| 1472 // We allow a STW collection only if a full | |
| 1473 // collection was requested. | |
| 1474 return full || should_allocate(size, tlab); // FIX ME !!! | |
| 1475 // This and promotion failure handling are connected at the | |
| 1476 // hip and should be fixed by untying them. | |
| 1477 } | |
| 1478 | |
| 1479 bool CMSCollector::shouldConcurrentCollect() { | |
| 1480 if (_full_gc_requested) { | |
| 1481 if (Verbose && PrintGCDetails) { | |
| 1482 gclog_or_tty->print_cr("CMSCollector: collect because of explicit " | |
|
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1483 " gc request (or gc_locker)"); |
| 0 | 1484 } |
| 1485 return true; | |
| 1486 } | |
| 1487 | |
| 1488 // For debugging purposes, change the type of collection. | |
| 1489 // If the rotation is not on the concurrent collection | |
| 1490 // type, don't start a concurrent collection. | |
| 1491 NOT_PRODUCT( | |
| 1492 if (RotateCMSCollectionTypes && | |
| 1493 (_cmsGen->debug_collection_type() != | |
| 1494 ConcurrentMarkSweepGeneration::Concurrent_collection_type)) { | |
| 1495 assert(_cmsGen->debug_collection_type() != | |
| 1496 ConcurrentMarkSweepGeneration::Unknown_collection_type, | |
| 1497 "Bad cms collection type"); | |
| 1498 return false; | |
| 1499 } | |
| 1500 ) | |
| 1501 | |
| 1502 FreelistLocker x(this); | |
| 1503 // ------------------------------------------------------------------ | |
| 1504 // Print out lots of information which affects the initiation of | |
| 1505 // a collection. | |
| 1506 if (PrintCMSInitiationStatistics && stats().valid()) { | |
| 1507 gclog_or_tty->print("CMSCollector shouldConcurrentCollect: "); | |
| 1508 gclog_or_tty->stamp(); | |
| 1509 gclog_or_tty->print_cr(""); | |
| 1510 stats().print_on(gclog_or_tty); | |
| 1511 gclog_or_tty->print_cr("time_until_cms_gen_full %3.7f", | |
| 1512 stats().time_until_cms_gen_full()); | |
| 1513 gclog_or_tty->print_cr("free="SIZE_FORMAT, _cmsGen->free()); | |
| 1514 gclog_or_tty->print_cr("contiguous_available="SIZE_FORMAT, | |
| 1515 _cmsGen->contiguous_available()); | |
| 1516 gclog_or_tty->print_cr("promotion_rate=%g", stats().promotion_rate()); | |
| 1517 gclog_or_tty->print_cr("cms_allocation_rate=%g", stats().cms_allocation_rate()); | |
| 1518 gclog_or_tty->print_cr("occupancy=%3.7f", _cmsGen->occupancy()); | |
|
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1519 gclog_or_tty->print_cr("initiatingOccupancy=%3.7f", _cmsGen->initiating_occupancy()); |
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1520 gclog_or_tty->print_cr("initiatingPermOccupancy=%3.7f", _permGen->initiating_occupancy()); |
| 0 | 1521 } |
| 1522 // ------------------------------------------------------------------ | |
| 1523 | |
| 1524 // If the estimated time to complete a cms collection (cms_duration()) | |
| 1525 // is less than the estimated time remaining until the cms generation | |
| 1526 // is full, start a collection. | |
| 1527 if (!UseCMSInitiatingOccupancyOnly) { | |
| 1528 if (stats().valid()) { | |
| 1529 if (stats().time_until_cms_start() == 0.0) { | |
| 1530 return true; | |
| 1531 } | |
| 1532 } else { | |
| 1533 // We want to conservatively collect somewhat early in order | |
| 1534 // to try and "bootstrap" our CMS/promotion statistics; | |
| 1535 // this branch will not fire after the first successful CMS | |
| 1536 // collection because the stats should then be valid. | |
| 1537 if (_cmsGen->occupancy() >= _bootstrap_occupancy) { | |
| 1538 if (Verbose && PrintGCDetails) { | |
| 1539 gclog_or_tty->print_cr( | |
| 1540 " CMSCollector: collect for bootstrapping statistics:" | |
| 1541 " occupancy = %f, boot occupancy = %f", _cmsGen->occupancy(), | |
| 1542 _bootstrap_occupancy); | |
| 1543 } | |
| 1544 return true; | |
| 1545 } | |
| 1546 } | |
| 1547 } | |
| 1548 | |
| 1549 // Otherwise, we start a collection cycle if either the perm gen or | |
| 1550 // old gen want a collection cycle started. Each may use | |
| 1551 // an appropriate criterion for making this decision. | |
| 1552 // XXX We need to make sure that the gen expansion | |
|
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1553 // criterion dovetails well with this. XXX NEED TO FIX THIS |
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1554 if (_cmsGen->should_concurrent_collect()) { |
| 0 | 1555 if (Verbose && PrintGCDetails) { |
| 1556 gclog_or_tty->print_cr("CMS old gen initiated"); | |
| 1557 } | |
| 1558 return true; | |
| 1559 } | |
| 1560 | |
|
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1561 // We start a collection if we believe an incremental collection may fail; |
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1562 // this is not likely to be productive in practice because it's probably too |
|
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1563 // late anyway. |
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1564 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
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1565 assert(gch->collector_policy()->is_two_generation_policy(), |
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1566 "You may want to check the correctness of the following"); |
|
1994
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1567 if (gch->incremental_collection_will_fail(true /* consult_young */)) { |
|
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1568 if (Verbose && PrintGCDetails) { |
|
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1569 gclog_or_tty->print("CMSCollector: collect because incremental collection will fail "); |
| 0 | 1570 } |
| 1571 return true; | |
| 1572 } | |
| 1573 | |
|
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1574 if (CMSClassUnloadingEnabled && _permGen->should_concurrent_collect()) { |
|
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1575 bool res = update_should_unload_classes(); |
|
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1576 if (res) { |
|
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1577 if (Verbose && PrintGCDetails) { |
|
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1578 gclog_or_tty->print_cr("CMS perm gen initiated"); |
|
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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 | |
| 1586 // Clear _expansion_cause fields of constituent generations | |
| 1587 void CMSCollector::clear_expansion_cause() { | |
| 1588 _cmsGen->clear_expansion_cause(); | |
| 1589 _permGen->clear_expansion_cause(); | |
| 1590 } | |
| 1591 | |
|
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1592 // We should be conservative in starting a collection cycle. To |
|
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1593 // start too eagerly runs the risk of collecting too often in the |
|
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1594 // extreme. To collect too rarely falls back on full collections, |
|
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1595 // which works, even if not optimum in terms of concurrent work. |
|
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1596 // As a work around for too eagerly collecting, use the flag |
|
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1597 // UseCMSInitiatingOccupancyOnly. This also has the advantage of |
|
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1598 // giving the user an easily understandable way of controlling the |
|
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1599 // collections. |
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1600 // We want to start a new collection cycle if any of the following |
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1601 // conditions hold: |
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1602 // . our current occupancy exceeds the configured initiating occupancy |
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1603 // for this generation, or |
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1604 // . we recently needed to expand this space and have not, since that |
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1605 // expansion, done a collection of this generation, or |
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1606 // . the underlying space believes that it may be a good idea to initiate |
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1607 // a concurrent collection (this may be based on criteria such as the |
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1608 // following: the space uses linear allocation and linear allocation is |
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1609 // going to fail, or there is believed to be excessive fragmentation in |
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1610 // the generation, etc... or ... |
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1611 // [.(currently done by CMSCollector::shouldConcurrentCollect() only for |
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1612 // the case of the old generation, not the perm generation; see CR 6543076): |
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1613 // we may be approaching a point at which allocation requests may fail because |
|
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1614 // we will be out of sufficient free space given allocation rate estimates.] |
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1615 bool ConcurrentMarkSweepGeneration::should_concurrent_collect() const { |
|
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1616 |
| 0 | 1617 assert_lock_strong(freelistLock()); |
|
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1618 if (occupancy() > initiating_occupancy()) { |
| 0 | 1619 if (PrintGCDetails && Verbose) { |
| 1620 gclog_or_tty->print(" %s: collect because of occupancy %f / %f ", | |
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1621 short_name(), occupancy(), initiating_occupancy()); |
| 0 | 1622 } |
| 1623 return true; | |
| 1624 } | |
| 1625 if (UseCMSInitiatingOccupancyOnly) { | |
| 1626 return false; | |
| 1627 } | |
| 1628 if (expansion_cause() == CMSExpansionCause::_satisfy_allocation) { | |
| 1629 if (PrintGCDetails && Verbose) { | |
| 1630 gclog_or_tty->print(" %s: collect because expanded for allocation ", | |
| 1631 short_name()); | |
| 1632 } | |
| 1633 return true; | |
| 1634 } | |
|
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1635 if (_cmsSpace->should_concurrent_collect()) { |
| 0 | 1636 if (PrintGCDetails && Verbose) { |
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1637 gclog_or_tty->print(" %s: collect because cmsSpace says so ", |
| 0 | 1638 short_name()); |
| 1639 } | |
| 1640 return true; | |
| 1641 } | |
| 1642 return false; | |
| 1643 } | |
| 1644 | |
| 1645 void ConcurrentMarkSweepGeneration::collect(bool full, | |
| 1646 bool clear_all_soft_refs, | |
| 1647 size_t size, | |
| 1648 bool tlab) | |
| 1649 { | |
| 1650 collector()->collect(full, clear_all_soft_refs, size, tlab); | |
| 1651 } | |
| 1652 | |
| 1653 void CMSCollector::collect(bool full, | |
| 1654 bool clear_all_soft_refs, | |
| 1655 size_t size, | |
| 1656 bool tlab) | |
| 1657 { | |
| 1658 if (!UseCMSCollectionPassing && _collectorState > Idling) { | |
| 1659 // For debugging purposes skip the collection if the state | |
| 1660 // is not currently idle | |
| 1661 if (TraceCMSState) { | |
| 1662 gclog_or_tty->print_cr("Thread " INTPTR_FORMAT " skipped full:%d CMS state %d", | |
| 1663 Thread::current(), full, _collectorState); | |
| 1664 } | |
| 1665 return; | |
| 1666 } | |
| 1667 | |
| 1668 // The following "if" branch is present for defensive reasons. | |
| 1669 // In the current uses of this interface, it can be replaced with: | |
| 1670 // assert(!GC_locker.is_active(), "Can't be called otherwise"); | |
| 1671 // But I am not placing that assert here to allow future | |
| 1672 // generality in invoking this interface. | |
| 1673 if (GC_locker::is_active()) { | |
| 1674 // A consistency test for GC_locker | |
| 1675 assert(GC_locker::needs_gc(), "Should have been set already"); | |
| 1676 // Skip this foreground collection, instead | |
| 1677 // expanding the heap if necessary. | |
| 1678 // Need the free list locks for the call to free() in compute_new_size() | |
| 1679 compute_new_size(); | |
| 1680 return; | |
| 1681 } | |
| 1682 acquire_control_and_collect(full, clear_all_soft_refs); | |
| 1683 _full_gcs_since_conc_gc++; | |
| 1684 | |
| 1685 } | |
| 1686 | |
| 1687 void CMSCollector::request_full_gc(unsigned int full_gc_count) { | |
| 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; | |
| 1693 CGC_lock->notify(); // nudge CMS thread | |
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1694 } else { |
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1695 assert(gc_count > full_gc_count, "Error: causal loop"); |
| 0 | 1696 } |
| 1697 } | |
| 1698 | |
| 1699 | |
| 1700 // The foreground and background collectors need to coordinate in order | |
| 1701 // to make sure that they do not mutually interfere with CMS collections. | |
| 1702 // When a background collection is active, | |
| 1703 // the foreground collector may need to take over (preempt) and | |
| 1704 // synchronously complete an ongoing collection. Depending on the | |
| 1705 // frequency of the background collections and the heap usage | |
| 1706 // of the application, this preemption can be seldom or frequent. | |
| 1707 // There are only certain | |
| 1708 // points in the background collection that the "collection-baton" | |
| 1709 // can be passed to the foreground collector. | |
| 1710 // | |
| 1711 // The foreground collector will wait for the baton before | |
| 1712 // starting any part of the collection. The foreground collector | |
| 1713 // will only wait at one location. | |
| 1714 // | |
| 1715 // The background collector will yield the baton before starting a new | |
| 1716 // phase of the collection (e.g., before initial marking, marking from roots, | |
| 1717 // precleaning, final re-mark, sweep etc.) This is normally done at the head | |
| 1718 // of the loop which switches the phases. The background collector does some | |
| 1719 // of the phases (initial mark, final re-mark) with the world stopped. | |
| 1720 // Because of locking involved in stopping the world, | |
| 1721 // the foreground collector should not block waiting for the background | |
| 1722 // collector when it is doing a stop-the-world phase. The background | |
| 1723 // collector will yield the baton at an additional point just before | |
| 1724 // it enters a stop-the-world phase. Once the world is stopped, the | |
| 1725 // background collector checks the phase of the collection. If the | |
| 1726 // phase has not changed, it proceeds with the collection. If the | |
| 1727 // phase has changed, it skips that phase of the collection. See | |
| 1728 // the comments on the use of the Heap_lock in collect_in_background(). | |
| 1729 // | |
| 1730 // Variable used in baton passing. | |
| 1731 // _foregroundGCIsActive - Set to true by the foreground collector when | |
| 1732 // it wants the baton. The foreground clears it when it has finished | |
| 1733 // the collection. | |
| 1734 // _foregroundGCShouldWait - Set to true by the background collector | |
| 1735 // when it is running. The foreground collector waits while | |
| 1736 // _foregroundGCShouldWait is true. | |
| 1737 // CGC_lock - monitor used to protect access to the above variables | |
| 1738 // and to notify the foreground and background collectors. | |
| 1739 // _collectorState - current state of the CMS collection. | |
| 1740 // | |
| 1741 // The foreground collector | |
| 1742 // acquires the CGC_lock | |
| 1743 // sets _foregroundGCIsActive | |
| 1744 // waits on the CGC_lock for _foregroundGCShouldWait to be false | |
| 1745 // various locks acquired in preparation for the collection | |
| 1746 // are released so as not to block the background collector | |
| 1747 // that is in the midst of a collection | |
| 1748 // proceeds with the collection | |
| 1749 // clears _foregroundGCIsActive | |
| 1750 // returns | |
| 1751 // | |
| 1752 // The background collector in a loop iterating on the phases of the | |
| 1753 // collection | |
| 1754 // acquires the CGC_lock | |
| 1755 // sets _foregroundGCShouldWait | |
| 1756 // if _foregroundGCIsActive is set | |
| 1757 // clears _foregroundGCShouldWait, notifies _CGC_lock | |
| 1758 // waits on _CGC_lock for _foregroundGCIsActive to become false | |
| 1759 // and exits the loop. | |
| 1760 // otherwise | |
| 1761 // proceed with that phase of the collection | |
| 1762 // if the phase is a stop-the-world phase, | |
| 1763 // yield the baton once more just before enqueueing | |
| 1764 // the stop-world CMS operation (executed by the VM thread). | |
| 1765 // returns after all phases of the collection are done | |
| 1766 // | |
| 1767 | |
| 1768 void CMSCollector::acquire_control_and_collect(bool full, | |
| 1769 bool clear_all_soft_refs) { | |
| 1770 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); | |
| 1771 assert(!Thread::current()->is_ConcurrentGC_thread(), | |
| 1772 "shouldn't try to acquire control from self!"); | |
| 1773 | |
| 1774 // Start the protocol for acquiring control of the | |
| 1775 // collection from the background collector (aka CMS thread). | |
| 1776 assert(ConcurrentMarkSweepThread::vm_thread_has_cms_token(), | |
| 1777 "VM thread should have CMS token"); | |
| 1778 // Remember the possibly interrupted state of an ongoing | |
| 1779 // concurrent collection | |
| 1780 CollectorState first_state = _collectorState; | |
| 1781 | |
| 1782 // Signal to a possibly ongoing concurrent collection that | |
| 1783 // we want to do a foreground collection. | |
| 1784 _foregroundGCIsActive = true; | |
| 1785 | |
| 1786 // Disable incremental mode during a foreground collection. | |
| 1787 ICMSDisabler icms_disabler; | |
| 1788 | |
| 1789 // release locks and wait for a notify from the background collector | |
| 1790 // releasing the locks in only necessary for phases which | |
| 1791 // do yields to improve the granularity of the collection. | |
| 1792 assert_lock_strong(bitMapLock()); | |
| 1793 // We need to lock the Free list lock for the space that we are | |
| 1794 // currently collecting. | |
| 1795 assert(haveFreelistLocks(), "Must be holding free list locks"); | |
| 1796 bitMapLock()->unlock(); | |
| 1797 releaseFreelistLocks(); | |
| 1798 { | |
| 1799 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
| 1800 if (_foregroundGCShouldWait) { | |
| 1801 // We are going to be waiting for action for the CMS thread; | |
| 1802 // it had better not be gone (for instance at shutdown)! | |
| 1803 assert(ConcurrentMarkSweepThread::cmst() != NULL, | |
| 1804 "CMS thread must be running"); | |
| 1805 // Wait here until the background collector gives us the go-ahead | |
| 1806 ConcurrentMarkSweepThread::clear_CMS_flag( | |
| 1807 ConcurrentMarkSweepThread::CMS_vm_has_token); // release token | |
| 1808 // Get a possibly blocked CMS thread going: | |
| 1809 // Note that we set _foregroundGCIsActive true above, | |
| 1810 // without protection of the CGC_lock. | |
| 1811 CGC_lock->notify(); | |
| 1812 assert(!ConcurrentMarkSweepThread::vm_thread_wants_cms_token(), | |
| 1813 "Possible deadlock"); | |
| 1814 while (_foregroundGCShouldWait) { | |
| 1815 // wait for notification | |
| 1816 CGC_lock->wait(Mutex::_no_safepoint_check_flag); | |
| 1817 // Possibility of delay/starvation here, since CMS token does | |
| 1818 // not know to give priority to VM thread? Actually, i think | |
| 1819 // there wouldn't be any delay/starvation, but the proof of | |
| 1820 // that "fact" (?) appears non-trivial. XXX 20011219YSR | |
| 1821 } | |
| 1822 ConcurrentMarkSweepThread::set_CMS_flag( | |
| 1823 ConcurrentMarkSweepThread::CMS_vm_has_token); | |
| 1824 } | |
| 1825 } | |
| 1826 // The CMS_token is already held. Get back the other locks. | |
| 1827 assert(ConcurrentMarkSweepThread::vm_thread_has_cms_token(), | |
| 1828 "VM thread should have CMS token"); | |
| 1829 getFreelistLocks(); | |
| 1830 bitMapLock()->lock_without_safepoint_check(); | |
| 1831 if (TraceCMSState) { | |
| 1832 gclog_or_tty->print_cr("CMS foreground collector has asked for control " | |
| 1833 INTPTR_FORMAT " with first state %d", Thread::current(), first_state); | |
| 1834 gclog_or_tty->print_cr(" gets control with state %d", _collectorState); | |
| 1835 } | |
| 1836 | |
| 1837 // Check if we need to do a compaction, or if not, whether | |
| 1838 // we need to start the mark-sweep from scratch. | |
| 1839 bool should_compact = false; | |
| 1840 bool should_start_over = false; | |
| 1841 decide_foreground_collection_type(clear_all_soft_refs, | |
| 1842 &should_compact, &should_start_over); | |
| 1843 | |
| 1844 NOT_PRODUCT( | |
| 1845 if (RotateCMSCollectionTypes) { | |
| 1846 if (_cmsGen->debug_collection_type() == | |
| 1847 ConcurrentMarkSweepGeneration::MSC_foreground_collection_type) { | |
| 1848 should_compact = true; | |
| 1849 } else if (_cmsGen->debug_collection_type() == | |
| 1850 ConcurrentMarkSweepGeneration::MS_foreground_collection_type) { | |
| 1851 should_compact = false; | |
| 1852 } | |
| 1853 } | |
| 1854 ) | |
| 1855 | |
| 1856 if (PrintGCDetails && first_state > Idling) { | |
| 1857 GCCause::Cause cause = GenCollectedHeap::heap()->gc_cause(); | |
| 1858 if (GCCause::is_user_requested_gc(cause) || | |
| 1859 GCCause::is_serviceability_requested_gc(cause)) { | |
| 1860 gclog_or_tty->print(" (concurrent mode interrupted)"); | |
| 1861 } else { | |
| 1862 gclog_or_tty->print(" (concurrent mode failure)"); | |
| 1863 } | |
| 1864 } | |
| 1865 | |
| 1866 if (should_compact) { | |
| 1867 // If the collection is being acquired from the background | |
| 1868 // collector, there may be references on the discovered | |
| 1869 // references lists that have NULL referents (being those | |
| 1870 // that were concurrently cleared by a mutator) or | |
| 1871 // that are no longer active (having been enqueued concurrently | |
| 1872 // by the mutator). | |
| 1873 // Scrub the list of those references because Mark-Sweep-Compact | |
| 1874 // code assumes referents are not NULL and that all discovered | |
| 1875 // Reference objects are active. | |
| 1876 ref_processor()->clean_up_discovered_references(); | |
| 1877 | |
| 1878 do_compaction_work(clear_all_soft_refs); | |
| 1879 | |
| 1880 // Has the GC time limit been exceeded? | |
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1881 DefNewGeneration* young_gen = _young_gen->as_DefNewGeneration(); |
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1882 size_t max_eden_size = young_gen->max_capacity() - |
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1883 young_gen->to()->capacity() - |
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1884 young_gen->from()->capacity(); |
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1885 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
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1886 GCCause::Cause gc_cause = gch->gc_cause(); |
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1887 size_policy()->check_gc_overhead_limit(_young_gen->used(), |
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1888 young_gen->eden()->used(), |
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1889 _cmsGen->max_capacity(), |
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1890 max_eden_size, |
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1891 full, |
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1892 gc_cause, |
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1893 gch->collector_policy()); |
| 0 | 1894 } else { |
| 1895 do_mark_sweep_work(clear_all_soft_refs, first_state, | |
| 1896 should_start_over); | |
| 1897 } | |
| 1898 // Reset the expansion cause, now that we just completed | |
| 1899 // a collection cycle. | |
| 1900 clear_expansion_cause(); | |
| 1901 _foregroundGCIsActive = false; | |
| 1902 return; | |
| 1903 } | |
| 1904 | |
| 1905 // Resize the perm generation and the tenured generation | |
| 1906 // after obtaining the free list locks for the | |
| 1907 // two generations. | |
| 1908 void CMSCollector::compute_new_size() { | |
| 1909 assert_locked_or_safepoint(Heap_lock); | |
| 1910 FreelistLocker z(this); | |
| 1911 _permGen->compute_new_size(); | |
| 1912 _cmsGen->compute_new_size(); | |
| 1913 } | |
| 1914 | |
| 1915 // A work method used by foreground collection to determine | |
| 1916 // what type of collection (compacting or not, continuing or fresh) | |
| 1917 // it should do. | |
| 1918 // NOTE: the intent is to make UseCMSCompactAtFullCollection | |
| 1919 // and CMSCompactWhenClearAllSoftRefs the default in the future | |
| 1920 // and do away with the flags after a suitable period. | |
| 1921 void CMSCollector::decide_foreground_collection_type( | |
| 1922 bool clear_all_soft_refs, bool* should_compact, | |
| 1923 bool* should_start_over) { | |
| 1924 // Normally, we'll compact only if the UseCMSCompactAtFullCollection | |
| 1925 // flag is set, and we have either requested a System.gc() or | |
| 1926 // the number of full gc's since the last concurrent cycle | |
| 1927 // has exceeded the threshold set by CMSFullGCsBeforeCompaction, | |
| 1928 // or if an incremental collection has failed | |
| 1929 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 1930 assert(gch->collector_policy()->is_two_generation_policy(), | |
| 1931 "You may want to check the correctness of the following"); | |
| 1932 // Inform cms gen if this was due to partial collection failing. | |
| 1933 // The CMS gen may use this fact to determine its expansion policy. | |
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1934 if (gch->incremental_collection_will_fail(false /* don't consult_young */)) { |
| 0 | 1935 assert(!_cmsGen->incremental_collection_failed(), |
| 1936 "Should have been noticed, reacted to and cleared"); | |
| 1937 _cmsGen->set_incremental_collection_failed(); | |
| 1938 } | |
| 1939 *should_compact = | |
| 1940 UseCMSCompactAtFullCollection && | |
| 1941 ((_full_gcs_since_conc_gc >= CMSFullGCsBeforeCompaction) || | |
| 1942 GCCause::is_user_requested_gc(gch->gc_cause()) || | |
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1943 gch->incremental_collection_will_fail(true /* consult_young */)); |
| 0 | 1944 *should_start_over = false; |
| 1945 if (clear_all_soft_refs && !*should_compact) { | |
| 1946 // We are about to do a last ditch collection attempt | |
| 1947 // so it would normally make sense to do a compaction | |
| 1948 // to reclaim as much space as possible. | |
| 1949 if (CMSCompactWhenClearAllSoftRefs) { | |
| 1950 // Default: The rationale is that in this case either | |
| 1951 // we are past the final marking phase, in which case | |
| 1952 // we'd have to start over, or so little has been done | |
| 1953 // that there's little point in saving that work. Compaction | |
| 1954 // appears to be the sensible choice in either case. | |
| 1955 *should_compact = true; | |
| 1956 } else { | |
| 1957 // We have been asked to clear all soft refs, but not to | |
| 1958 // compact. Make sure that we aren't past the final checkpoint | |
| 1959 // phase, for that is where we process soft refs. If we are already | |
| 1960 // past that phase, we'll need to redo the refs discovery phase and | |
| 1961 // if necessary clear soft refs that weren't previously | |
| 1962 // cleared. We do so by remembering the phase in which | |
| 1963 // we came in, and if we are past the refs processing | |
| 1964 // phase, we'll choose to just redo the mark-sweep | |
| 1965 // collection from scratch. | |
| 1966 if (_collectorState > FinalMarking) { | |
| 1967 // We are past the refs processing phase; | |
| 1968 // start over and do a fresh synchronous CMS cycle | |
| 1969 _collectorState = Resetting; // skip to reset to start new cycle | |
| 1970 reset(false /* == !asynch */); | |
| 1971 *should_start_over = true; | |
| 1972 } // else we can continue a possibly ongoing current cycle | |
| 1973 } | |
| 1974 } | |
| 1975 } | |
| 1976 | |
| 1977 // A work method used by the foreground collector to do | |
| 1978 // a mark-sweep-compact. | |
| 1979 void CMSCollector::do_compaction_work(bool clear_all_soft_refs) { | |
| 1980 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 1981 TraceTime t("CMS:MSC ", PrintGCDetails && Verbose, true, gclog_or_tty); | |
| 1982 if (PrintGC && Verbose && !(GCCause::is_user_requested_gc(gch->gc_cause()))) { | |
| 1983 gclog_or_tty->print_cr("Compact ConcurrentMarkSweepGeneration after %d " | |
| 1984 "collections passed to foreground collector", _full_gcs_since_conc_gc); | |
| 1985 } | |
| 1986 | |
| 1987 // Sample collection interval time and reset for collection pause. | |
| 1988 if (UseAdaptiveSizePolicy) { | |
| 1989 size_policy()->msc_collection_begin(); | |
| 1990 } | |
| 1991 | |
| 1992 // Temporarily widen the span of the weak reference processing to | |
| 1993 // the entire heap. | |
| 1994 MemRegion new_span(GenCollectedHeap::heap()->reserved_region()); | |
|
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1995 ReferenceProcessorSpanMutator rp_mut_span(ref_processor(), new_span); |
| 0 | 1996 // Temporarily, clear the "is_alive_non_header" field of the |
| 1997 // reference processor. | |
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1998 ReferenceProcessorIsAliveMutator rp_mut_closure(ref_processor(), NULL); |
| 0 | 1999 // Temporarily make reference _processing_ single threaded (non-MT). |
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2000 ReferenceProcessorMTProcMutator rp_mut_mt_processing(ref_processor(), false); |
| 0 | 2001 // Temporarily make refs discovery atomic |
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2002 ReferenceProcessorAtomicMutator rp_mut_atomic(ref_processor(), true); |
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2003 // Temporarily make reference _discovery_ single threaded (non-MT) |
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2004 ReferenceProcessorMTDiscoveryMutator rp_mut_discovery(ref_processor(), false); |
| 0 | 2005 |
| 2006 ref_processor()->set_enqueuing_is_done(false); | |
| 2007 ref_processor()->enable_discovery(); | |
|
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2008 ref_processor()->setup_policy(clear_all_soft_refs); |
| 0 | 2009 // If an asynchronous collection finishes, the _modUnionTable is |
| 2010 // all clear. If we are assuming the collection from an asynchronous | |
| 2011 // collection, clear the _modUnionTable. | |
| 2012 assert(_collectorState != Idling || _modUnionTable.isAllClear(), | |
| 2013 "_modUnionTable should be clear if the baton was not passed"); | |
| 2014 _modUnionTable.clear_all(); | |
| 2015 | |
| 2016 // We must adjust the allocation statistics being maintained | |
| 2017 // in the free list space. We do so by reading and clearing | |
| 2018 // the sweep timer and updating the block flux rate estimates below. | |
|
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2019 assert(!_intra_sweep_timer.is_active(), "_intra_sweep_timer should be inactive"); |
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2020 if (_inter_sweep_timer.is_active()) { |
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2021 _inter_sweep_timer.stop(); |
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2022 // Note that we do not use this sample to update the _inter_sweep_estimate. |
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2023 _cmsGen->cmsSpace()->beginSweepFLCensus((float)(_inter_sweep_timer.seconds()), |
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2024 _inter_sweep_estimate.padded_average(), |
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2025 _intra_sweep_estimate.padded_average()); |
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2026 } |
| 0 | 2027 |
|
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2028 { |
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2029 TraceCMSMemoryManagerStats tmms(gch->gc_cause()); |
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2030 } |
| 0 | 2031 GenMarkSweep::invoke_at_safepoint(_cmsGen->level(), |
| 2032 ref_processor(), clear_all_soft_refs); | |
| 2033 #ifdef ASSERT | |
| 2034 CompactibleFreeListSpace* cms_space = _cmsGen->cmsSpace(); | |
| 2035 size_t free_size = cms_space->free(); | |
| 2036 assert(free_size == | |
| 2037 pointer_delta(cms_space->end(), cms_space->compaction_top()) | |
| 2038 * HeapWordSize, | |
| 2039 "All the free space should be compacted into one chunk at top"); | |
| 2040 assert(cms_space->dictionary()->totalChunkSize( | |
| 2041 debug_only(cms_space->freelistLock())) == 0 || | |
| 2042 cms_space->totalSizeInIndexedFreeLists() == 0, | |
| 2043 "All the free space should be in a single chunk"); | |
| 2044 size_t num = cms_space->totalCount(); | |
| 2045 assert((free_size == 0 && num == 0) || | |
| 2046 (free_size > 0 && (num == 1 || num == 2)), | |
| 2047 "There should be at most 2 free chunks after compaction"); | |
| 2048 #endif // ASSERT | |
| 2049 _collectorState = Resetting; | |
| 2050 assert(_restart_addr == NULL, | |
| 2051 "Should have been NULL'd before baton was passed"); | |
| 2052 reset(false /* == !asynch */); | |
| 2053 _cmsGen->reset_after_compaction(); | |
|
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2054 _concurrent_cycles_since_last_unload = 0; |
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2055 |
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2056 if (verifying() && !should_unload_classes()) { |
| 0 | 2057 perm_gen_verify_bit_map()->clear_all(); |
| 2058 } | |
| 2059 | |
| 2060 // Clear any data recorded in the PLAB chunk arrays. | |
| 2061 if (_survivor_plab_array != NULL) { | |
| 2062 reset_survivor_plab_arrays(); | |
| 2063 } | |
| 2064 | |
| 2065 // Adjust the per-size allocation stats for the next epoch. | |
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2066 _cmsGen->cmsSpace()->endSweepFLCensus(sweep_count() /* fake */); |
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2067 // Restart the "inter sweep timer" for the next epoch. |
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2068 _inter_sweep_timer.reset(); |
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2069 _inter_sweep_timer.start(); |
| 0 | 2070 |
| 2071 // Sample collection pause time and reset for collection interval. | |
| 2072 if (UseAdaptiveSizePolicy) { | |
| 2073 size_policy()->msc_collection_end(gch->gc_cause()); | |
| 2074 } | |
| 2075 | |
| 2076 // For a mark-sweep-compact, compute_new_size() will be called | |
| 2077 // in the heap's do_collection() method. | |
| 2078 } | |
| 2079 | |
| 2080 // A work method used by the foreground collector to do | |
| 2081 // a mark-sweep, after taking over from a possibly on-going | |
| 2082 // concurrent mark-sweep collection. | |
| 2083 void CMSCollector::do_mark_sweep_work(bool clear_all_soft_refs, | |
| 2084 CollectorState first_state, bool should_start_over) { | |
| 2085 if (PrintGC && Verbose) { | |
| 2086 gclog_or_tty->print_cr("Pass concurrent collection to foreground " | |
| 2087 "collector with count %d", | |
| 2088 _full_gcs_since_conc_gc); | |
| 2089 } | |
| 2090 switch (_collectorState) { | |
| 2091 case Idling: | |
| 2092 if (first_state == Idling || should_start_over) { | |
| 2093 // The background GC was not active, or should | |
| 2094 // restarted from scratch; start the cycle. | |
| 2095 _collectorState = InitialMarking; | |
| 2096 } | |
| 2097 // If first_state was not Idling, then a background GC | |
| 2098 // was in progress and has now finished. No need to do it | |
| 2099 // again. Leave the state as Idling. | |
| 2100 break; | |
| 2101 case Precleaning: | |
| 2102 // In the foreground case don't do the precleaning since | |
| 2103 // it is not done concurrently and there is extra work | |
| 2104 // required. | |
| 2105 _collectorState = FinalMarking; | |
| 2106 } | |
| 2107 if (PrintGCDetails && | |
| 2108 (_collectorState > Idling || | |
| 2109 !GCCause::is_user_requested_gc(GenCollectedHeap::heap()->gc_cause()))) { | |
| 2110 gclog_or_tty->print(" (concurrent mode failure)"); | |
| 2111 } | |
| 2112 collect_in_foreground(clear_all_soft_refs); | |
| 2113 | |
| 2114 // For a mark-sweep, compute_new_size() will be called | |
| 2115 // in the heap's do_collection() method. | |
| 2116 } | |
| 2117 | |
| 2118 | |
| 2119 void CMSCollector::getFreelistLocks() const { | |
| 2120 // Get locks for all free lists in all generations that this | |
| 2121 // collector is responsible for | |
| 2122 _cmsGen->freelistLock()->lock_without_safepoint_check(); | |
| 2123 _permGen->freelistLock()->lock_without_safepoint_check(); | |
| 2124 } | |
| 2125 | |
| 2126 void CMSCollector::releaseFreelistLocks() const { | |
| 2127 // Release locks for all free lists in all generations that this | |
| 2128 // collector is responsible for | |
| 2129 _cmsGen->freelistLock()->unlock(); | |
| 2130 _permGen->freelistLock()->unlock(); | |
| 2131 } | |
| 2132 | |
| 2133 bool CMSCollector::haveFreelistLocks() const { | |
| 2134 // Check locks for all free lists in all generations that this | |
| 2135 // collector is responsible for | |
| 2136 assert_lock_strong(_cmsGen->freelistLock()); | |
| 2137 assert_lock_strong(_permGen->freelistLock()); | |
| 2138 PRODUCT_ONLY(ShouldNotReachHere()); | |
| 2139 return true; | |
| 2140 } | |
| 2141 | |
| 2142 // A utility class that is used by the CMS collector to | |
| 2143 // temporarily "release" the foreground collector from its | |
| 2144 // usual obligation to wait for the background collector to | |
| 2145 // complete an ongoing phase before proceeding. | |
| 2146 class ReleaseForegroundGC: public StackObj { | |
| 2147 private: | |
| 2148 CMSCollector* _c; | |
| 2149 public: | |
| 2150 ReleaseForegroundGC(CMSCollector* c) : _c(c) { | |
| 2151 assert(_c->_foregroundGCShouldWait, "Else should not need to call"); | |
| 2152 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
| 2153 // allow a potentially blocked foreground collector to proceed | |
| 2154 _c->_foregroundGCShouldWait = false; | |
| 2155 if (_c->_foregroundGCIsActive) { | |
| 2156 CGC_lock->notify(); | |
| 2157 } | |
| 2158 assert(!ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 2159 "Possible deadlock"); | |
| 2160 } | |
| 2161 | |
| 2162 ~ReleaseForegroundGC() { | |
| 2163 assert(!_c->_foregroundGCShouldWait, "Usage protocol violation?"); | |
| 2164 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
| 2165 _c->_foregroundGCShouldWait = true; | |
| 2166 } | |
| 2167 }; | |
| 2168 | |
| 2169 // There are separate collect_in_background and collect_in_foreground because of | |
| 2170 // the different locking requirements of the background collector and the | |
| 2171 // foreground collector. There was originally an attempt to share | |
| 2172 // one "collect" method between the background collector and the foreground | |
| 2173 // collector but the if-then-else required made it cleaner to have | |
| 2174 // separate methods. | |
| 2175 void CMSCollector::collect_in_background(bool clear_all_soft_refs) { | |
| 2176 assert(Thread::current()->is_ConcurrentGC_thread(), | |
| 2177 "A CMS asynchronous collection is only allowed on a CMS thread."); | |
| 2178 | |
| 2179 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 2180 { | |
| 2181 bool safepoint_check = Mutex::_no_safepoint_check_flag; | |
| 2182 MutexLockerEx hl(Heap_lock, safepoint_check); | |
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2183 FreelistLocker fll(this); |
| 0 | 2184 MutexLockerEx x(CGC_lock, safepoint_check); |
| 2185 if (_foregroundGCIsActive || !UseAsyncConcMarkSweepGC) { | |
| 2186 // The foreground collector is active or we're | |
| 2187 // not using asynchronous collections. Skip this | |
| 2188 // background collection. | |
| 2189 assert(!_foregroundGCShouldWait, "Should be clear"); | |
| 2190 return; | |
| 2191 } else { | |
| 2192 assert(_collectorState == Idling, "Should be idling before start."); | |
| 2193 _collectorState = InitialMarking; | |
| 2194 // Reset the expansion cause, now that we are about to begin | |
| 2195 // a new cycle. | |
| 2196 clear_expansion_cause(); | |
| 2197 } | |
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2198 // Decide if we want to enable class unloading as part of the |
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2199 // ensuing concurrent GC cycle. |
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2200 update_should_unload_classes(); |
| 0 | 2201 _full_gc_requested = false; // acks all outstanding full gc requests |
| 2202 // Signal that we are about to start a collection | |
| 2203 gch->increment_total_full_collections(); // ... starting a collection cycle | |
| 2204 _collection_count_start = gch->total_full_collections(); | |
| 2205 } | |
| 2206 | |
| 2207 // Used for PrintGC | |
| 2208 size_t prev_used; | |
| 2209 if (PrintGC && Verbose) { | |
| 2210 prev_used = _cmsGen->used(); // XXXPERM | |
| 2211 } | |
| 2212 | |
| 2213 // The change of the collection state is normally done at this level; | |
| 2214 // the exceptions are phases that are executed while the world is | |
| 2215 // stopped. For those phases the change of state is done while the | |
| 2216 // world is stopped. For baton passing purposes this allows the | |
| 2217 // background collector to finish the phase and change state atomically. | |
| 2218 // The foreground collector cannot wait on a phase that is done | |
| 2219 // while the world is stopped because the foreground collector already | |
| 2220 // has the world stopped and would deadlock. | |
| 2221 while (_collectorState != Idling) { | |
| 2222 if (TraceCMSState) { | |
| 2223 gclog_or_tty->print_cr("Thread " INTPTR_FORMAT " in CMS state %d", | |
| 2224 Thread::current(), _collectorState); | |
| 2225 } | |
| 2226 // The foreground collector | |
| 2227 // holds the Heap_lock throughout its collection. | |
| 2228 // holds the CMS token (but not the lock) | |
| 2229 // except while it is waiting for the background collector to yield. | |
| 2230 // | |
| 2231 // The foreground collector should be blocked (not for long) | |
| 2232 // if the background collector is about to start a phase | |
| 2233 // executed with world stopped. If the background | |
| 2234 // collector has already started such a phase, the | |
| 2235 // foreground collector is blocked waiting for the | |
| 2236 // Heap_lock. The stop-world phases (InitialMarking and FinalMarking) | |
| 2237 // are executed in the VM thread. | |
| 2238 // | |
| 2239 // The locking order is | |
| 2240 // PendingListLock (PLL) -- if applicable (FinalMarking) | |
| 2241 // Heap_lock (both this & PLL locked in VM_CMS_Operation::prologue()) | |
| 2242 // CMS token (claimed in | |
| 2243 // stop_world_and_do() --> | |
| 2244 // safepoint_synchronize() --> | |
| 2245 // CMSThread::synchronize()) | |
| 2246 | |
| 2247 { | |
| 2248 // Check if the FG collector wants us to yield. | |
| 2249 CMSTokenSync x(true); // is cms thread | |
| 2250 if (waitForForegroundGC()) { | |
| 2251 // We yielded to a foreground GC, nothing more to be | |
| 2252 // done this round. | |
| 2253 assert(_foregroundGCShouldWait == false, "We set it to false in " | |
| 2254 "waitForForegroundGC()"); | |
| 2255 if (TraceCMSState) { | |
| 2256 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT | |
| 2257 " exiting collection CMS state %d", | |
| 2258 Thread::current(), _collectorState); | |
| 2259 } | |
| 2260 return; | |
| 2261 } else { | |
| 2262 // The background collector can run but check to see if the | |
| 2263 // foreground collector has done a collection while the | |
| 2264 // background collector was waiting to get the CGC_lock | |
| 2265 // above. If yes, break so that _foregroundGCShouldWait | |
| 2266 // is cleared before returning. | |
| 2267 if (_collectorState == Idling) { | |
| 2268 break; | |
| 2269 } | |
| 2270 } | |
| 2271 } | |
| 2272 | |
| 2273 assert(_foregroundGCShouldWait, "Foreground collector, if active, " | |
| 2274 "should be waiting"); | |
| 2275 | |
| 2276 switch (_collectorState) { | |
| 2277 case InitialMarking: | |
| 2278 { | |
| 2279 ReleaseForegroundGC x(this); | |
| 2280 stats().record_cms_begin(); | |
| 2281 | |
| 2282 VM_CMS_Initial_Mark initial_mark_op(this); | |
| 2283 VMThread::execute(&initial_mark_op); | |
| 2284 } | |
| 2285 // The collector state may be any legal state at this point | |
| 2286 // since the background collector may have yielded to the | |
| 2287 // foreground collector. | |
| 2288 break; | |
| 2289 case Marking: | |
| 2290 // initial marking in checkpointRootsInitialWork has been completed | |
| 2291 if (markFromRoots(true)) { // we were successful | |
| 2292 assert(_collectorState == Precleaning, "Collector state should " | |
| 2293 "have changed"); | |
| 2294 } else { | |
| 2295 assert(_foregroundGCIsActive, "Internal state inconsistency"); | |
| 2296 } | |
| 2297 break; | |
| 2298 case Precleaning: | |
| 2299 if (UseAdaptiveSizePolicy) { | |
| 2300 size_policy()->concurrent_precleaning_begin(); | |
| 2301 } | |
| 2302 // marking from roots in markFromRoots has been completed | |
| 2303 preclean(); | |
| 2304 if (UseAdaptiveSizePolicy) { | |
| 2305 size_policy()->concurrent_precleaning_end(); | |
| 2306 } | |
| 2307 assert(_collectorState == AbortablePreclean || | |
| 2308 _collectorState == FinalMarking, | |
| 2309 "Collector state should have changed"); | |
| 2310 break; | |
| 2311 case AbortablePreclean: | |
| 2312 if (UseAdaptiveSizePolicy) { | |
| 2313 size_policy()->concurrent_phases_resume(); | |
| 2314 } | |
| 2315 abortable_preclean(); | |
| 2316 if (UseAdaptiveSizePolicy) { | |
| 2317 size_policy()->concurrent_precleaning_end(); | |
| 2318 } | |
| 2319 assert(_collectorState == FinalMarking, "Collector state should " | |
| 2320 "have changed"); | |
| 2321 break; | |
| 2322 case FinalMarking: | |
| 2323 { | |
| 2324 ReleaseForegroundGC x(this); | |
| 2325 | |
| 2326 VM_CMS_Final_Remark final_remark_op(this); | |
| 2327 VMThread::execute(&final_remark_op); | |
| 935 | 2328 } |
| 0 | 2329 assert(_foregroundGCShouldWait, "block post-condition"); |
| 2330 break; | |
| 2331 case Sweeping: | |
| 2332 if (UseAdaptiveSizePolicy) { | |
| 2333 size_policy()->concurrent_sweeping_begin(); | |
| 2334 } | |
| 2335 // final marking in checkpointRootsFinal has been completed | |
| 2336 sweep(true); | |
| 2337 assert(_collectorState == Resizing, "Collector state change " | |
| 2338 "to Resizing must be done under the free_list_lock"); | |
| 2339 _full_gcs_since_conc_gc = 0; | |
| 2340 | |
| 2341 // Stop the timers for adaptive size policy for the concurrent phases | |
| 2342 if (UseAdaptiveSizePolicy) { | |
| 2343 size_policy()->concurrent_sweeping_end(); | |
| 2344 size_policy()->concurrent_phases_end(gch->gc_cause(), | |
| 2345 gch->prev_gen(_cmsGen)->capacity(), | |
| 2346 _cmsGen->free()); | |
| 2347 } | |
| 2348 | |
| 2349 case Resizing: { | |
| 2350 // Sweeping has been completed... | |
| 2351 // At this point the background collection has completed. | |
| 2352 // Don't move the call to compute_new_size() down | |
| 2353 // into code that might be executed if the background | |
| 2354 // collection was preempted. | |
| 2355 { | |
| 2356 ReleaseForegroundGC x(this); // unblock FG collection | |
| 2357 MutexLockerEx y(Heap_lock, Mutex::_no_safepoint_check_flag); | |
| 2358 CMSTokenSync z(true); // not strictly needed. | |
| 2359 if (_collectorState == Resizing) { | |
| 2360 compute_new_size(); | |
| 2361 _collectorState = Resetting; | |
| 2362 } else { | |
| 2363 assert(_collectorState == Idling, "The state should only change" | |
| 2364 " because the foreground collector has finished the collection"); | |
| 2365 } | |
| 2366 } | |
| 2367 break; | |
| 2368 } | |
| 2369 case Resetting: | |
| 2370 // CMS heap resizing has been completed | |
| 2371 reset(true); | |
| 2372 assert(_collectorState == Idling, "Collector state should " | |
| 2373 "have changed"); | |
| 2374 stats().record_cms_end(); | |
| 2375 // Don't move the concurrent_phases_end() and compute_new_size() | |
| 2376 // calls to here because a preempted background collection | |
| 2377 // has it's state set to "Resetting". | |
| 2378 break; | |
| 2379 case Idling: | |
| 2380 default: | |
| 2381 ShouldNotReachHere(); | |
| 2382 break; | |
| 2383 } | |
| 2384 if (TraceCMSState) { | |
| 2385 gclog_or_tty->print_cr(" Thread " INTPTR_FORMAT " done - next CMS state %d", | |
| 2386 Thread::current(), _collectorState); | |
| 2387 } | |
| 2388 assert(_foregroundGCShouldWait, "block post-condition"); | |
| 2389 } | |
| 2390 | |
| 2391 // Should this be in gc_epilogue? | |
| 2392 collector_policy()->counters()->update_counters(); | |
| 2393 | |
| 2394 { | |
| 2395 // Clear _foregroundGCShouldWait and, in the event that the | |
| 2396 // foreground collector is waiting, notify it, before | |
| 2397 // returning. | |
| 2398 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
| 2399 _foregroundGCShouldWait = false; | |
| 2400 if (_foregroundGCIsActive) { | |
| 2401 CGC_lock->notify(); | |
| 2402 } | |
| 2403 assert(!ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 2404 "Possible deadlock"); | |
| 2405 } | |
| 2406 if (TraceCMSState) { | |
| 2407 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT | |
| 2408 " exiting collection CMS state %d", | |
| 2409 Thread::current(), _collectorState); | |
| 2410 } | |
| 2411 if (PrintGC && Verbose) { | |
| 2412 _cmsGen->print_heap_change(prev_used); | |
| 2413 } | |
| 2414 } | |
| 2415 | |
| 2416 void CMSCollector::collect_in_foreground(bool clear_all_soft_refs) { | |
| 2417 assert(_foregroundGCIsActive && !_foregroundGCShouldWait, | |
| 2418 "Foreground collector should be waiting, not executing"); | |
| 2419 assert(Thread::current()->is_VM_thread(), "A foreground collection" | |
| 2420 "may only be done by the VM Thread with the world stopped"); | |
| 2421 assert(ConcurrentMarkSweepThread::vm_thread_has_cms_token(), | |
| 2422 "VM thread should have CMS token"); | |
| 2423 | |
| 2424 NOT_PRODUCT(TraceTime t("CMS:MS (foreground) ", PrintGCDetails && Verbose, | |
| 2425 true, gclog_or_tty);) | |
| 2426 if (UseAdaptiveSizePolicy) { | |
| 2427 size_policy()->ms_collection_begin(); | |
| 2428 } | |
| 2429 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact); | |
| 2430 | |
| 2431 HandleMark hm; // Discard invalid handles created during verification | |
| 2432 | |
| 2433 if (VerifyBeforeGC && | |
| 2434 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
| 2435 Universe::verify(true); | |
| 2436 } | |
| 2437 | |
|
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2438 // Snapshot the soft reference policy to be used in this collection cycle. |
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2439 ref_processor()->setup_policy(clear_all_soft_refs); |
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2440 |
| 0 | 2441 bool init_mark_was_synchronous = false; // until proven otherwise |
| 2442 while (_collectorState != Idling) { | |
| 2443 if (TraceCMSState) { | |
| 2444 gclog_or_tty->print_cr("Thread " INTPTR_FORMAT " in CMS state %d", | |
| 2445 Thread::current(), _collectorState); | |
| 2446 } | |
| 2447 switch (_collectorState) { | |
| 2448 case InitialMarking: | |
| 2449 init_mark_was_synchronous = true; // fact to be exploited in re-mark | |
| 2450 checkpointRootsInitial(false); | |
| 2451 assert(_collectorState == Marking, "Collector state should have changed" | |
| 2452 " within checkpointRootsInitial()"); | |
| 2453 break; | |
| 2454 case Marking: | |
| 2455 // initial marking in checkpointRootsInitialWork has been completed | |
| 2456 if (VerifyDuringGC && | |
| 2457 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
| 2458 gclog_or_tty->print("Verify before initial mark: "); | |
| 2459 Universe::verify(true); | |
| 2460 } | |
| 2461 { | |
| 2462 bool res = markFromRoots(false); | |
| 2463 assert(res && _collectorState == FinalMarking, "Collector state should " | |
| 2464 "have changed"); | |
| 2465 break; | |
| 2466 } | |
| 2467 case FinalMarking: | |
| 2468 if (VerifyDuringGC && | |
| 2469 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
| 2470 gclog_or_tty->print("Verify before re-mark: "); | |
| 2471 Universe::verify(true); | |
| 2472 } | |
| 2473 checkpointRootsFinal(false, clear_all_soft_refs, | |
| 2474 init_mark_was_synchronous); | |
| 2475 assert(_collectorState == Sweeping, "Collector state should not " | |
| 2476 "have changed within checkpointRootsFinal()"); | |
| 2477 break; | |
| 2478 case Sweeping: | |
| 2479 // final marking in checkpointRootsFinal has been completed | |
| 2480 if (VerifyDuringGC && | |
| 2481 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
| 2482 gclog_or_tty->print("Verify before sweep: "); | |
| 2483 Universe::verify(true); | |
| 2484 } | |
| 2485 sweep(false); | |
| 2486 assert(_collectorState == Resizing, "Incorrect state"); | |
| 2487 break; | |
| 2488 case Resizing: { | |
| 2489 // Sweeping has been completed; the actual resize in this case | |
| 2490 // is done separately; nothing to be done in this state. | |
| 2491 _collectorState = Resetting; | |
| 2492 break; | |
| 2493 } | |
| 2494 case Resetting: | |
| 2495 // The heap has been resized. | |
| 2496 if (VerifyDuringGC && | |
| 2497 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
| 2498 gclog_or_tty->print("Verify before reset: "); | |
| 2499 Universe::verify(true); | |
| 2500 } | |
| 2501 reset(false); | |
| 2502 assert(_collectorState == Idling, "Collector state should " | |
| 2503 "have changed"); | |
| 2504 break; | |
| 2505 case Precleaning: | |
| 2506 case AbortablePreclean: | |
| 2507 // Elide the preclean phase | |
| 2508 _collectorState = FinalMarking; | |
| 2509 break; | |
| 2510 default: | |
| 2511 ShouldNotReachHere(); | |
| 2512 } | |
| 2513 if (TraceCMSState) { | |
| 2514 gclog_or_tty->print_cr(" Thread " INTPTR_FORMAT " done - next CMS state %d", | |
| 2515 Thread::current(), _collectorState); | |
| 2516 } | |
| 2517 } | |
| 2518 | |
| 2519 if (UseAdaptiveSizePolicy) { | |
| 2520 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 2521 size_policy()->ms_collection_end(gch->gc_cause()); | |
| 2522 } | |
| 2523 | |
| 2524 if (VerifyAfterGC && | |
| 2525 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
| 2526 Universe::verify(true); | |
| 2527 } | |
| 2528 if (TraceCMSState) { | |
| 2529 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT | |
| 2530 " exiting collection CMS state %d", | |
| 2531 Thread::current(), _collectorState); | |
| 2532 } | |
| 2533 } | |
| 2534 | |
| 2535 bool CMSCollector::waitForForegroundGC() { | |
| 2536 bool res = false; | |
| 2537 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 2538 "CMS thread should have CMS token"); | |
| 2539 // Block the foreground collector until the | |
| 2540 // background collectors decides whether to | |
| 2541 // yield. | |
| 2542 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
| 2543 _foregroundGCShouldWait = true; | |
| 2544 if (_foregroundGCIsActive) { | |
| 2545 // The background collector yields to the | |
| 2546 // foreground collector and returns a value | |
| 2547 // indicating that it has yielded. The foreground | |
| 2548 // collector can proceed. | |
| 2549 res = true; | |
| 2550 _foregroundGCShouldWait = false; | |
| 2551 ConcurrentMarkSweepThread::clear_CMS_flag( | |
| 2552 ConcurrentMarkSweepThread::CMS_cms_has_token); | |
| 2553 ConcurrentMarkSweepThread::set_CMS_flag( | |
| 2554 ConcurrentMarkSweepThread::CMS_cms_wants_token); | |
| 2555 // Get a possibly blocked foreground thread going | |
| 2556 CGC_lock->notify(); | |
| 2557 if (TraceCMSState) { | |
| 2558 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT " waiting at CMS state %d", | |
| 2559 Thread::current(), _collectorState); | |
| 2560 } | |
| 2561 while (_foregroundGCIsActive) { | |
| 2562 CGC_lock->wait(Mutex::_no_safepoint_check_flag); | |
| 2563 } | |
| 2564 ConcurrentMarkSweepThread::set_CMS_flag( | |
| 2565 ConcurrentMarkSweepThread::CMS_cms_has_token); | |
| 2566 ConcurrentMarkSweepThread::clear_CMS_flag( | |
| 2567 ConcurrentMarkSweepThread::CMS_cms_wants_token); | |
| 2568 } | |
| 2569 if (TraceCMSState) { | |
| 2570 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT " continuing at CMS state %d", | |
| 2571 Thread::current(), _collectorState); | |
| 2572 } | |
| 2573 return res; | |
| 2574 } | |
| 2575 | |
| 2576 // Because of the need to lock the free lists and other structures in | |
| 2577 // the collector, common to all the generations that the collector is | |
| 2578 // collecting, we need the gc_prologues of individual CMS generations | |
| 2579 // delegate to their collector. It may have been simpler had the | |
| 2580 // current infrastructure allowed one to call a prologue on a | |
| 2581 // collector. In the absence of that we have the generation's | |
| 2582 // prologue delegate to the collector, which delegates back | |
| 2583 // some "local" work to a worker method in the individual generations | |
| 2584 // that it's responsible for collecting, while itself doing any | |
| 2585 // work common to all generations it's responsible for. A similar | |
| 2586 // comment applies to the gc_epilogue()'s. | |
| 2587 // The role of the varaible _between_prologue_and_epilogue is to | |
| 2588 // enforce the invocation protocol. | |
| 2589 void CMSCollector::gc_prologue(bool full) { | |
| 2590 // Call gc_prologue_work() for each CMSGen and PermGen that | |
| 2591 // we are responsible for. | |
| 2592 | |
| 2593 // The following locking discipline assumes that we are only called | |
| 2594 // when the world is stopped. | |
| 2595 assert(SafepointSynchronize::is_at_safepoint(), "world is stopped assumption"); | |
| 2596 | |
| 2597 // The CMSCollector prologue must call the gc_prologues for the | |
| 2598 // "generations" (including PermGen if any) that it's responsible | |
| 2599 // for. | |
| 2600 | |
| 2601 assert( Thread::current()->is_VM_thread() | |
| 2602 || ( CMSScavengeBeforeRemark | |
| 2603 && Thread::current()->is_ConcurrentGC_thread()), | |
| 2604 "Incorrect thread type for prologue execution"); | |
| 2605 | |
| 2606 if (_between_prologue_and_epilogue) { | |
| 2607 // We have already been invoked; this is a gc_prologue delegation | |
| 2608 // from yet another CMS generation that we are responsible for, just | |
| 2609 // ignore it since all relevant work has already been done. | |
| 2610 return; | |
| 2611 } | |
| 2612 | |
| 2613 // set a bit saying prologue has been called; cleared in epilogue | |
| 2614 _between_prologue_and_epilogue = true; | |
| 2615 // Claim locks for common data structures, then call gc_prologue_work() | |
| 2616 // for each CMSGen and PermGen that we are responsible for. | |
| 2617 | |
| 2618 getFreelistLocks(); // gets free list locks on constituent spaces | |
| 2619 bitMapLock()->lock_without_safepoint_check(); | |
| 2620 | |
| 2621 // Should call gc_prologue_work() for all cms gens we are responsible for | |
| 2622 bool registerClosure = _collectorState >= Marking | |
| 2623 && _collectorState < Sweeping; | |
|
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2624 ModUnionClosure* muc = CollectedHeap::use_parallel_gc_threads() ? |
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|
2625 &_modUnionClosurePar |
| 0 | 2626 : &_modUnionClosure; |
| 2627 _cmsGen->gc_prologue_work(full, registerClosure, muc); | |
| 2628 _permGen->gc_prologue_work(full, registerClosure, muc); | |
| 2629 | |
| 2630 if (!full) { | |
| 2631 stats().record_gc0_begin(); | |
| 2632 } | |
| 2633 } | |
| 2634 | |
| 2635 void ConcurrentMarkSweepGeneration::gc_prologue(bool full) { | |
| 2636 // Delegate to CMScollector which knows how to coordinate between | |
| 2637 // this and any other CMS generations that it is responsible for | |
| 2638 // collecting. | |
| 2639 collector()->gc_prologue(full); | |
| 2640 } | |
| 2641 | |
| 2642 // This is a "private" interface for use by this generation's CMSCollector. | |
| 2643 // Not to be called directly by any other entity (for instance, | |
| 2644 // GenCollectedHeap, which calls the "public" gc_prologue method above). | |
| 2645 void ConcurrentMarkSweepGeneration::gc_prologue_work(bool full, | |
| 2646 bool registerClosure, ModUnionClosure* modUnionClosure) { | |
| 2647 assert(!incremental_collection_failed(), "Shouldn't be set yet"); | |
| 2648 assert(cmsSpace()->preconsumptionDirtyCardClosure() == NULL, | |
| 2649 "Should be NULL"); | |
| 2650 if (registerClosure) { | |
| 2651 cmsSpace()->setPreconsumptionDirtyCardClosure(modUnionClosure); | |
| 2652 } | |
| 2653 cmsSpace()->gc_prologue(); | |
| 2654 // Clear stat counters | |
| 2655 NOT_PRODUCT( | |
| 2656 assert(_numObjectsPromoted == 0, "check"); | |
| 2657 assert(_numWordsPromoted == 0, "check"); | |
| 2658 if (Verbose && PrintGC) { | |
| 2659 gclog_or_tty->print("Allocated "SIZE_FORMAT" objects, " | |
| 2660 SIZE_FORMAT" bytes concurrently", | |
| 2661 _numObjectsAllocated, _numWordsAllocated*sizeof(HeapWord)); | |
| 2662 } | |
| 2663 _numObjectsAllocated = 0; | |
| 2664 _numWordsAllocated = 0; | |
| 2665 ) | |
| 2666 } | |
| 2667 | |
| 2668 void CMSCollector::gc_epilogue(bool full) { | |
| 2669 // The following locking discipline assumes that we are only called | |
| 2670 // when the world is stopped. | |
| 2671 assert(SafepointSynchronize::is_at_safepoint(), | |
| 2672 "world is stopped assumption"); | |
| 2673 | |
| 2674 // Currently the CMS epilogue (see CompactibleFreeListSpace) merely checks | |
| 2675 // if linear allocation blocks need to be appropriately marked to allow the | |
| 2676 // the blocks to be parsable. We also check here whether we need to nudge the | |
| 2677 // CMS collector thread to start a new cycle (if it's not already active). | |
| 2678 assert( Thread::current()->is_VM_thread() | |
| 2679 || ( CMSScavengeBeforeRemark | |
| 2680 && Thread::current()->is_ConcurrentGC_thread()), | |
| 2681 "Incorrect thread type for epilogue execution"); | |
| 2682 | |
| 2683 if (!_between_prologue_and_epilogue) { | |
| 2684 // We have already been invoked; this is a gc_epilogue delegation | |
| 2685 // from yet another CMS generation that we are responsible for, just | |
| 2686 // ignore it since all relevant work has already been done. | |
| 2687 return; | |
| 2688 } | |
| 2689 assert(haveFreelistLocks(), "must have freelist locks"); | |
| 2690 assert_lock_strong(bitMapLock()); | |
| 2691 | |
| 2692 _cmsGen->gc_epilogue_work(full); | |
| 2693 _permGen->gc_epilogue_work(full); | |
| 2694 | |
| 2695 if (_collectorState == AbortablePreclean || _collectorState == Precleaning) { | |
| 2696 // in case sampling was not already enabled, enable it | |
| 2697 _start_sampling = true; | |
| 2698 } | |
| 2699 // reset _eden_chunk_array so sampling starts afresh | |
| 2700 _eden_chunk_index = 0; | |
| 2701 | |
| 2702 size_t cms_used = _cmsGen->cmsSpace()->used(); | |
| 2703 size_t perm_used = _permGen->cmsSpace()->used(); | |
| 2704 | |
| 2705 // update performance counters - this uses a special version of | |
| 2706 // update_counters() that allows the utilization to be passed as a | |
| 2707 // parameter, avoiding multiple calls to used(). | |
| 2708 // | |
| 2709 _cmsGen->update_counters(cms_used); | |
| 2710 _permGen->update_counters(perm_used); | |
| 2711 | |
| 2712 if (CMSIncrementalMode) { | |
| 2713 icms_update_allocation_limits(); | |
| 2714 } | |
| 2715 | |
| 2716 bitMapLock()->unlock(); | |
| 2717 releaseFreelistLocks(); | |
| 2718 | |
| 2719 _between_prologue_and_epilogue = false; // ready for next cycle | |
| 2720 } | |
| 2721 | |
| 2722 void ConcurrentMarkSweepGeneration::gc_epilogue(bool full) { | |
| 2723 collector()->gc_epilogue(full); | |
| 2724 | |
| 2725 // Also reset promotion tracking in par gc thread states. | |
|
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2726 if (CollectedHeap::use_parallel_gc_threads()) { |
| 0 | 2727 for (uint i = 0; i < ParallelGCThreads; i++) { |
|
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|
2728 _par_gc_thread_states[i]->promo.stopTrackingPromotions(i); |
| 0 | 2729 } |
| 2730 } | |
| 2731 } | |
| 2732 | |
| 2733 void ConcurrentMarkSweepGeneration::gc_epilogue_work(bool full) { | |
| 2734 assert(!incremental_collection_failed(), "Should have been cleared"); | |
| 2735 cmsSpace()->setPreconsumptionDirtyCardClosure(NULL); | |
| 2736 cmsSpace()->gc_epilogue(); | |
| 2737 // Print stat counters | |
| 2738 NOT_PRODUCT( | |
| 2739 assert(_numObjectsAllocated == 0, "check"); | |
| 2740 assert(_numWordsAllocated == 0, "check"); | |
| 2741 if (Verbose && PrintGC) { | |
| 2742 gclog_or_tty->print("Promoted "SIZE_FORMAT" objects, " | |
| 2743 SIZE_FORMAT" bytes", | |
| 2744 _numObjectsPromoted, _numWordsPromoted*sizeof(HeapWord)); | |
| 2745 } | |
| 2746 _numObjectsPromoted = 0; | |
| 2747 _numWordsPromoted = 0; | |
| 2748 ) | |
| 2749 | |
| 2750 if (PrintGC && Verbose) { | |
| 2751 // Call down the chain in contiguous_available needs the freelistLock | |
| 2752 // so print this out before releasing the freeListLock. | |
| 2753 gclog_or_tty->print(" Contiguous available "SIZE_FORMAT" bytes ", | |
| 2754 contiguous_available()); | |
| 2755 } | |
| 2756 } | |
| 2757 | |
| 2758 #ifndef PRODUCT | |
| 2759 bool CMSCollector::have_cms_token() { | |
| 2760 Thread* thr = Thread::current(); | |
| 2761 if (thr->is_VM_thread()) { | |
| 2762 return ConcurrentMarkSweepThread::vm_thread_has_cms_token(); | |
| 2763 } else if (thr->is_ConcurrentGC_thread()) { | |
| 2764 return ConcurrentMarkSweepThread::cms_thread_has_cms_token(); | |
| 2765 } else if (thr->is_GC_task_thread()) { | |
| 2766 return ConcurrentMarkSweepThread::vm_thread_has_cms_token() && | |
| 2767 ParGCRareEvent_lock->owned_by_self(); | |
| 2768 } | |
| 2769 return false; | |
| 2770 } | |
| 2771 #endif | |
| 2772 | |
| 2773 // Check reachability of the given heap address in CMS generation, | |
| 2774 // treating all other generations as roots. | |
| 2775 bool CMSCollector::is_cms_reachable(HeapWord* addr) { | |
| 2776 // We could "guarantee" below, rather than assert, but i'll | |
| 2777 // leave these as "asserts" so that an adventurous debugger | |
| 2778 // could try this in the product build provided some subset of | |
| 2779 // the conditions were met, provided they were intersted in the | |
| 2780 // results and knew that the computation below wouldn't interfere | |
| 2781 // with other concurrent computations mutating the structures | |
| 2782 // being read or written. | |
| 2783 assert(SafepointSynchronize::is_at_safepoint(), | |
| 2784 "Else mutations in object graph will make answer suspect"); | |
| 2785 assert(have_cms_token(), "Should hold cms token"); | |
| 2786 assert(haveFreelistLocks(), "must hold free list locks"); | |
| 2787 assert_lock_strong(bitMapLock()); | |
| 2788 | |
| 2789 // Clear the marking bit map array before starting, but, just | |
| 2790 // for kicks, first report if the given address is already marked | |
| 2791 gclog_or_tty->print_cr("Start: Address 0x%x is%s marked", addr, | |
| 2792 _markBitMap.isMarked(addr) ? "" : " not"); | |
| 2793 | |
| 2794 if (verify_after_remark()) { | |
| 2795 MutexLockerEx x(verification_mark_bm()->lock(), Mutex::_no_safepoint_check_flag); | |
| 2796 bool result = verification_mark_bm()->isMarked(addr); | |
| 2797 gclog_or_tty->print_cr("TransitiveMark: Address 0x%x %s marked", addr, | |
| 2798 result ? "IS" : "is NOT"); | |
| 2799 return result; | |
| 2800 } else { | |
| 2801 gclog_or_tty->print_cr("Could not compute result"); | |
| 2802 return false; | |
| 2803 } | |
| 2804 } | |
| 2805 | |
| 2806 //////////////////////////////////////////////////////// | |
| 2807 // CMS Verification Support | |
| 2808 //////////////////////////////////////////////////////// | |
| 2809 // Following the remark phase, the following invariant | |
| 2810 // should hold -- each object in the CMS heap which is | |
| 2811 // marked in markBitMap() should be marked in the verification_mark_bm(). | |
| 2812 | |
| 2813 class VerifyMarkedClosure: public BitMapClosure { | |
| 2814 CMSBitMap* _marks; | |
| 2815 bool _failed; | |
| 2816 | |
| 2817 public: | |
| 2818 VerifyMarkedClosure(CMSBitMap* bm): _marks(bm), _failed(false) {} | |
| 2819 | |
|
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2820 bool do_bit(size_t offset) { |
| 0 | 2821 HeapWord* addr = _marks->offsetToHeapWord(offset); |
| 2822 if (!_marks->isMarked(addr)) { | |
|
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2823 oop(addr)->print_on(gclog_or_tty); |
| 0 | 2824 gclog_or_tty->print_cr(" ("INTPTR_FORMAT" should have been marked)", addr); |
| 2825 _failed = true; | |
| 2826 } | |
|
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2827 return true; |
| 0 | 2828 } |
| 2829 | |
| 2830 bool failed() { return _failed; } | |
| 2831 }; | |
| 2832 | |
| 2833 bool CMSCollector::verify_after_remark() { | |
| 2834 gclog_or_tty->print(" [Verifying CMS Marking... "); | |
| 2835 MutexLockerEx ml(verification_mark_bm()->lock(), Mutex::_no_safepoint_check_flag); | |
| 2836 static bool init = false; | |
| 2837 | |
| 2838 assert(SafepointSynchronize::is_at_safepoint(), | |
| 2839 "Else mutations in object graph will make answer suspect"); | |
| 2840 assert(have_cms_token(), | |
| 2841 "Else there may be mutual interference in use of " | |
| 2842 " verification data structures"); | |
| 2843 assert(_collectorState > Marking && _collectorState <= Sweeping, | |
| 2844 "Else marking info checked here may be obsolete"); | |
| 2845 assert(haveFreelistLocks(), "must hold free list locks"); | |
| 2846 assert_lock_strong(bitMapLock()); | |
| 2847 | |
| 2848 | |
| 2849 // Allocate marking bit map if not already allocated | |
| 2850 if (!init) { // first time | |
| 2851 if (!verification_mark_bm()->allocate(_span)) { | |
| 2852 return false; | |
| 2853 } | |
| 2854 init = true; | |
| 2855 } | |
| 2856 | |
| 2857 assert(verification_mark_stack()->isEmpty(), "Should be empty"); | |
| 2858 | |
| 2859 // Turn off refs discovery -- so we will be tracing through refs. | |
| 2860 // This is as intended, because by this time | |
| 2861 // GC must already have cleared any refs that need to be cleared, | |
| 2862 // and traced those that need to be marked; moreover, | |
| 2863 // the marking done here is not going to intefere in any | |
| 2864 // way with the marking information used by GC. | |
| 2865 NoRefDiscovery no_discovery(ref_processor()); | |
| 2866 | |
| 2867 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact;) | |
| 2868 | |
| 2869 // Clear any marks from a previous round | |
| 2870 verification_mark_bm()->clear_all(); | |
| 2871 assert(verification_mark_stack()->isEmpty(), "markStack should be empty"); | |
|
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2872 verify_work_stacks_empty(); |
| 0 | 2873 |
| 2874 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 2875 gch->ensure_parsability(false); // fill TLABs, but no need to retire them | |
| 2876 // Update the saved marks which may affect the root scans. | |
| 2877 gch->save_marks(); | |
| 2878 | |
| 2879 if (CMSRemarkVerifyVariant == 1) { | |
| 2880 // In this first variant of verification, we complete | |
| 2881 // all marking, then check if the new marks-verctor is | |
| 2882 // a subset of the CMS marks-vector. | |
| 2883 verify_after_remark_work_1(); | |
| 2884 } else if (CMSRemarkVerifyVariant == 2) { | |
| 2885 // In this second variant of verification, we flag an error | |
| 2886 // (i.e. an object reachable in the new marks-vector not reachable | |
| 2887 // in the CMS marks-vector) immediately, also indicating the | |
| 2888 // identify of an object (A) that references the unmarked object (B) -- | |
| 2889 // presumably, a mutation to A failed to be picked up by preclean/remark? | |
| 2890 verify_after_remark_work_2(); | |
| 2891 } else { | |
| 2892 warning("Unrecognized value %d for CMSRemarkVerifyVariant", | |
| 2893 CMSRemarkVerifyVariant); | |
| 2894 } | |
| 2895 gclog_or_tty->print(" done] "); | |
| 2896 return true; | |
| 2897 } | |
| 2898 | |
| 2899 void CMSCollector::verify_after_remark_work_1() { | |
| 2900 ResourceMark rm; | |
| 2901 HandleMark hm; | |
| 2902 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 2903 | |
| 2904 // Mark from roots one level into CMS | |
|
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2905 MarkRefsIntoClosure notOlder(_span, verification_mark_bm()); |
| 0 | 2906 gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel. |
| 2907 | |
| 2908 gch->gen_process_strong_roots(_cmsGen->level(), | |
| 2909 true, // younger gens are roots | |
|
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2910 true, // activate StrongRootsScope |
| 0 | 2911 true, // collecting perm gen |
| 2912 SharedHeap::ScanningOption(roots_scanning_options()), | |
|
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2913 ¬Older, |
|
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2914 true, // walk code active on stacks |
|
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2915 NULL); |
| 0 | 2916 |
| 2917 // Now mark from the roots | |
| 2918 assert(_revisitStack.isEmpty(), "Should be empty"); | |
| 2919 MarkFromRootsClosure markFromRootsClosure(this, _span, | |
| 2920 verification_mark_bm(), verification_mark_stack(), &_revisitStack, | |
| 2921 false /* don't yield */, true /* verifying */); | |
| 2922 assert(_restart_addr == NULL, "Expected pre-condition"); | |
| 2923 verification_mark_bm()->iterate(&markFromRootsClosure); | |
| 2924 while (_restart_addr != NULL) { | |
| 2925 // Deal with stack overflow: by restarting at the indicated | |
| 2926 // address. | |
| 2927 HeapWord* ra = _restart_addr; | |
| 2928 markFromRootsClosure.reset(ra); | |
| 2929 _restart_addr = NULL; | |
| 2930 verification_mark_bm()->iterate(&markFromRootsClosure, ra, _span.end()); | |
| 2931 } | |
| 2932 assert(verification_mark_stack()->isEmpty(), "Should have been drained"); | |
| 2933 verify_work_stacks_empty(); | |
| 2934 // Should reset the revisit stack above, since no class tree | |
| 2935 // surgery is forthcoming. | |
| 2936 _revisitStack.reset(); // throwing away all contents | |
| 2937 | |
| 2938 // Marking completed -- now verify that each bit marked in | |
| 2939 // verification_mark_bm() is also marked in markBitMap(); flag all | |
| 2940 // errors by printing corresponding objects. | |
| 2941 VerifyMarkedClosure vcl(markBitMap()); | |
| 2942 verification_mark_bm()->iterate(&vcl); | |
| 2943 if (vcl.failed()) { | |
| 2944 gclog_or_tty->print("Verification failed"); | |
|
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2945 Universe::heap()->print_on(gclog_or_tty); |
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2946 fatal("CMS: failed marking verification after remark"); |
| 0 | 2947 } |
| 2948 } | |
| 2949 | |
| 2950 void CMSCollector::verify_after_remark_work_2() { | |
| 2951 ResourceMark rm; | |
| 2952 HandleMark hm; | |
| 2953 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 2954 | |
| 2955 // Mark from roots one level into CMS | |
| 2956 MarkRefsIntoVerifyClosure notOlder(_span, verification_mark_bm(), | |
|
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2957 markBitMap()); |
| 0 | 2958 gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel. |
| 2959 gch->gen_process_strong_roots(_cmsGen->level(), | |
| 2960 true, // younger gens are roots | |
|
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2961 true, // activate StrongRootsScope |
| 0 | 2962 true, // collecting perm gen |
| 2963 SharedHeap::ScanningOption(roots_scanning_options()), | |
|
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2964 ¬Older, |
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2965 true, // walk code active on stacks |
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|
2966 NULL); |
| 0 | 2967 |
| 2968 // Now mark from the roots | |
| 2969 assert(_revisitStack.isEmpty(), "Should be empty"); | |
| 2970 MarkFromRootsVerifyClosure markFromRootsClosure(this, _span, | |
| 2971 verification_mark_bm(), markBitMap(), verification_mark_stack()); | |
| 2972 assert(_restart_addr == NULL, "Expected pre-condition"); | |
| 2973 verification_mark_bm()->iterate(&markFromRootsClosure); | |
| 2974 while (_restart_addr != NULL) { | |
| 2975 // Deal with stack overflow: by restarting at the indicated | |
| 2976 // address. | |
| 2977 HeapWord* ra = _restart_addr; | |
| 2978 markFromRootsClosure.reset(ra); | |
| 2979 _restart_addr = NULL; | |
| 2980 verification_mark_bm()->iterate(&markFromRootsClosure, ra, _span.end()); | |
| 2981 } | |
| 2982 assert(verification_mark_stack()->isEmpty(), "Should have been drained"); | |
| 2983 verify_work_stacks_empty(); | |
| 2984 // Should reset the revisit stack above, since no class tree | |
| 2985 // surgery is forthcoming. | |
| 2986 _revisitStack.reset(); // throwing away all contents | |
| 2987 | |
| 2988 // Marking completed -- now verify that each bit marked in | |
| 2989 // verification_mark_bm() is also marked in markBitMap(); flag all | |
| 2990 // errors by printing corresponding objects. | |
| 2991 VerifyMarkedClosure vcl(markBitMap()); | |
| 2992 verification_mark_bm()->iterate(&vcl); | |
| 2993 assert(!vcl.failed(), "Else verification above should not have succeeded"); | |
| 2994 } | |
| 2995 | |
| 2996 void ConcurrentMarkSweepGeneration::save_marks() { | |
| 2997 // delegate to CMS space | |
| 2998 cmsSpace()->save_marks(); | |
| 2999 for (uint i = 0; i < ParallelGCThreads; i++) { | |
| 3000 _par_gc_thread_states[i]->promo.startTrackingPromotions(); | |
| 3001 } | |
| 3002 } | |
| 3003 | |
| 3004 bool ConcurrentMarkSweepGeneration::no_allocs_since_save_marks() { | |
| 3005 return cmsSpace()->no_allocs_since_save_marks(); | |
| 3006 } | |
| 3007 | |
| 3008 #define CMS_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \ | |
| 3009 \ | |
| 3010 void ConcurrentMarkSweepGeneration:: \ | |
| 3011 oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) { \ | |
| 3012 cl->set_generation(this); \ | |
| 3013 cmsSpace()->oop_since_save_marks_iterate##nv_suffix(cl); \ | |
| 3014 cl->reset_generation(); \ | |
| 3015 save_marks(); \ | |
| 3016 } | |
| 3017 | |
| 3018 ALL_SINCE_SAVE_MARKS_CLOSURES(CMS_SINCE_SAVE_MARKS_DEFN) | |
| 3019 | |
| 3020 void | |
| 3021 ConcurrentMarkSweepGeneration::object_iterate_since_last_GC(ObjectClosure* blk) | |
| 3022 { | |
| 3023 // Not currently implemented; need to do the following. -- ysr. | |
| 3024 // dld -- I think that is used for some sort of allocation profiler. So it | |
| 3025 // really means the objects allocated by the mutator since the last | |
| 3026 // GC. We could potentially implement this cheaply by recording only | |
| 3027 // the direct allocations in a side data structure. | |
| 3028 // | |
| 3029 // I think we probably ought not to be required to support these | |
| 3030 // iterations at any arbitrary point; I think there ought to be some | |
| 3031 // call to enable/disable allocation profiling in a generation/space, | |
| 3032 // and the iterator ought to return the objects allocated in the | |
| 3033 // gen/space since the enable call, or the last iterator call (which | |
| 3034 // will probably be at a GC.) That way, for gens like CM&S that would | |
| 3035 // require some extra data structure to support this, we only pay the | |
| 3036 // cost when it's in use... | |
| 3037 cmsSpace()->object_iterate_since_last_GC(blk); | |
| 3038 } | |
| 3039 | |
| 3040 void | |
| 3041 ConcurrentMarkSweepGeneration::younger_refs_iterate(OopsInGenClosure* cl) { | |
| 3042 cl->set_generation(this); | |
| 3043 younger_refs_in_space_iterate(_cmsSpace, cl); | |
| 3044 cl->reset_generation(); | |
| 3045 } | |
| 3046 | |
| 3047 void | |
| 3048 ConcurrentMarkSweepGeneration::oop_iterate(MemRegion mr, OopClosure* cl) { | |
| 3049 if (freelistLock()->owned_by_self()) { | |
| 3050 Generation::oop_iterate(mr, cl); | |
| 3051 } else { | |
| 3052 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 3053 Generation::oop_iterate(mr, cl); | |
| 3054 } | |
| 3055 } | |
| 3056 | |
| 3057 void | |
| 3058 ConcurrentMarkSweepGeneration::oop_iterate(OopClosure* cl) { | |
| 3059 if (freelistLock()->owned_by_self()) { | |
| 3060 Generation::oop_iterate(cl); | |
| 3061 } else { | |
| 3062 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 3063 Generation::oop_iterate(cl); | |
| 3064 } | |
| 3065 } | |
| 3066 | |
| 3067 void | |
| 3068 ConcurrentMarkSweepGeneration::object_iterate(ObjectClosure* cl) { | |
| 3069 if (freelistLock()->owned_by_self()) { | |
| 3070 Generation::object_iterate(cl); | |
| 3071 } else { | |
| 3072 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 3073 Generation::object_iterate(cl); | |
| 3074 } | |
| 3075 } | |
| 3076 | |
| 3077 void | |
|
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3078 ConcurrentMarkSweepGeneration::safe_object_iterate(ObjectClosure* cl) { |
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3079 if (freelistLock()->owned_by_self()) { |
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3080 Generation::safe_object_iterate(cl); |
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3081 } else { |
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3082 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); |
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3083 Generation::safe_object_iterate(cl); |
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3084 } |
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3085 } |
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3086 |
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3087 void |
| 0 | 3088 ConcurrentMarkSweepGeneration::pre_adjust_pointers() { |
| 3089 } | |
| 3090 | |
| 3091 void | |
| 3092 ConcurrentMarkSweepGeneration::post_compact() { | |
| 3093 } | |
| 3094 | |
| 3095 void | |
| 3096 ConcurrentMarkSweepGeneration::prepare_for_verify() { | |
| 3097 // Fix the linear allocation blocks to look like free blocks. | |
| 3098 | |
| 3099 // Locks are normally acquired/released in gc_prologue/gc_epilogue, but those | |
| 3100 // are not called when the heap is verified during universe initialization and | |
| 3101 // at vm shutdown. | |
| 3102 if (freelistLock()->owned_by_self()) { | |
| 3103 cmsSpace()->prepare_for_verify(); | |
| 3104 } else { | |
| 3105 MutexLockerEx fll(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 3106 cmsSpace()->prepare_for_verify(); | |
| 3107 } | |
| 3108 } | |
| 3109 | |
| 3110 void | |
| 3111 ConcurrentMarkSweepGeneration::verify(bool allow_dirty /* ignored */) { | |
| 3112 // Locks are normally acquired/released in gc_prologue/gc_epilogue, but those | |
| 3113 // are not called when the heap is verified during universe initialization and | |
| 3114 // at vm shutdown. | |
| 3115 if (freelistLock()->owned_by_self()) { | |
| 3116 cmsSpace()->verify(false /* ignored */); | |
| 3117 } else { | |
| 3118 MutexLockerEx fll(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 3119 cmsSpace()->verify(false /* ignored */); | |
| 3120 } | |
| 3121 } | |
| 3122 | |
| 3123 void CMSCollector::verify(bool allow_dirty /* ignored */) { | |
| 3124 _cmsGen->verify(allow_dirty); | |
| 3125 _permGen->verify(allow_dirty); | |
| 3126 } | |
| 3127 | |
| 3128 #ifndef PRODUCT | |
| 3129 bool CMSCollector::overflow_list_is_empty() const { | |
| 3130 assert(_num_par_pushes >= 0, "Inconsistency"); | |
| 3131 if (_overflow_list == NULL) { | |
| 3132 assert(_num_par_pushes == 0, "Inconsistency"); | |
| 3133 } | |
| 3134 return _overflow_list == NULL; | |
| 3135 } | |
| 3136 | |
| 3137 // The methods verify_work_stacks_empty() and verify_overflow_empty() | |
| 3138 // merely consolidate assertion checks that appear to occur together frequently. | |
| 3139 void CMSCollector::verify_work_stacks_empty() const { | |
| 3140 assert(_markStack.isEmpty(), "Marking stack should be empty"); | |
| 3141 assert(overflow_list_is_empty(), "Overflow list should be empty"); | |
| 3142 } | |
| 3143 | |
| 3144 void CMSCollector::verify_overflow_empty() const { | |
| 3145 assert(overflow_list_is_empty(), "Overflow list should be empty"); | |
| 3146 assert(no_preserved_marks(), "No preserved marks"); | |
| 3147 } | |
| 3148 #endif // PRODUCT | |
| 3149 | |
|
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3150 // Decide if we want to enable class unloading as part of the |
|
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3151 // ensuing concurrent GC cycle. We will collect the perm gen and |
|
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3152 // unload classes if it's the case that: |
|
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3153 // (1) an explicit gc request has been made and the flag |
|
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|
3154 // ExplicitGCInvokesConcurrentAndUnloadsClasses is set, OR |
|
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3155 // (2) (a) class unloading is enabled at the command line, and |
|
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|
3156 // (b) (i) perm gen threshold has been crossed, or |
|
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3157 // (ii) old gen is getting really full, or |
|
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3158 // (iii) the previous N CMS collections did not collect the |
|
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3159 // perm gen |
|
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3160 // NOTE: Provided there is no change in the state of the heap between |
|
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|
3161 // calls to this method, it should have idempotent results. Moreover, |
|
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|
3162 // its results should be monotonically increasing (i.e. going from 0 to 1, |
|
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|
3163 // but not 1 to 0) between successive calls between which the heap was |
|
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|
3164 // not collected. For the implementation below, it must thus rely on |
|
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|
3165 // the property that concurrent_cycles_since_last_unload() |
|
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3166 // will not decrease unless a collection cycle happened and that |
|
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3167 // _permGen->should_concurrent_collect() and _cmsGen->is_too_full() are |
|
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3168 // themselves also monotonic in that sense. See check_monotonicity() |
|
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3169 // below. |
|
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3170 bool CMSCollector::update_should_unload_classes() { |
|
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3171 _should_unload_classes = false; |
|
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3172 // Condition 1 above |
|
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3173 if (_full_gc_requested && ExplicitGCInvokesConcurrentAndUnloadsClasses) { |
|
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3174 _should_unload_classes = true; |
|
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3175 } else if (CMSClassUnloadingEnabled) { // Condition 2.a above |
|
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3176 // Disjuncts 2.b.(i,ii,iii) above |
|
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3177 _should_unload_classes = (concurrent_cycles_since_last_unload() >= |
|
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3178 CMSClassUnloadingMaxInterval) |
|
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3179 || _permGen->should_concurrent_collect() |
|
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3180 || _cmsGen->is_too_full(); |
|
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3181 } |
|
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3182 return _should_unload_classes; |
|
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3183 } |
|
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3184 |
|
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3185 bool ConcurrentMarkSweepGeneration::is_too_full() const { |
|
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3186 bool res = should_concurrent_collect(); |
|
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3187 res = res && (occupancy() > (double)CMSIsTooFullPercentage/100.0); |
|
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3188 return res; |
|
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3189 } |
|
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3190 |
| 0 | 3191 void CMSCollector::setup_cms_unloading_and_verification_state() { |
|
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3192 const bool should_verify = VerifyBeforeGC || VerifyAfterGC || VerifyDuringGC |
| 0 | 3193 || VerifyBeforeExit; |
|
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3194 const int rso = SharedHeap::SO_Strings | SharedHeap::SO_CodeCache; |
| 0 | 3195 |
|
94
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3196 if (should_unload_classes()) { // Should unload classes this cycle |
| 0 | 3197 remove_root_scanning_option(rso); // Shrink the root set appropriately |
| 3198 set_verifying(should_verify); // Set verification state for this cycle | |
| 3199 return; // Nothing else needs to be done at this time | |
| 3200 } | |
| 3201 | |
| 3202 // Not unloading classes this cycle | |
|
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3203 assert(!should_unload_classes(), "Inconsitency!"); |
|
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3204 if ((!verifying() || unloaded_classes_last_cycle()) && should_verify) { |
| 0 | 3205 // We were not verifying, or we _were_ unloading classes in the last cycle, |
| 3206 // AND some verification options are enabled this cycle; in this case, | |
| 3207 // we must make sure that the deadness map is allocated if not already so, | |
| 3208 // and cleared (if already allocated previously -- | |
| 3209 // CMSBitMap::sizeInBits() is used to determine if it's allocated). | |
| 3210 if (perm_gen_verify_bit_map()->sizeInBits() == 0) { | |
| 3211 if (!perm_gen_verify_bit_map()->allocate(_permGen->reserved())) { | |
| 3212 warning("Failed to allocate permanent generation verification CMS Bit Map;\n" | |
| 3213 "permanent generation verification disabled"); | |
| 3214 return; // Note that we leave verification disabled, so we'll retry this | |
| 3215 // allocation next cycle. We _could_ remember this failure | |
| 3216 // and skip further attempts and permanently disable verification | |
| 3217 // attempts if that is considered more desirable. | |
| 3218 } | |
| 3219 assert(perm_gen_verify_bit_map()->covers(_permGen->reserved()), | |
| 3220 "_perm_gen_ver_bit_map inconsistency?"); | |
| 3221 } else { | |
| 3222 perm_gen_verify_bit_map()->clear_all(); | |
| 3223 } | |
| 3224 // Include symbols, strings and code cache elements to prevent their resurrection. | |
| 3225 add_root_scanning_option(rso); | |
| 3226 set_verifying(true); | |
| 3227 } else if (verifying() && !should_verify) { | |
| 3228 // We were verifying, but some verification flags got disabled. | |
| 3229 set_verifying(false); | |
| 3230 // Exclude symbols, strings and code cache elements from root scanning to | |
| 3231 // reduce IM and RM pauses. | |
| 3232 remove_root_scanning_option(rso); | |
| 3233 } | |
| 3234 } | |
| 3235 | |
| 3236 | |
| 3237 #ifndef PRODUCT | |
| 3238 HeapWord* CMSCollector::block_start(const void* p) const { | |
| 3239 const HeapWord* addr = (HeapWord*)p; | |
| 3240 if (_span.contains(p)) { | |
| 3241 if (_cmsGen->cmsSpace()->is_in_reserved(addr)) { | |
| 3242 return _cmsGen->cmsSpace()->block_start(p); | |
| 3243 } else { | |
| 3244 assert(_permGen->cmsSpace()->is_in_reserved(addr), | |
| 3245 "Inconsistent _span?"); | |
| 3246 return _permGen->cmsSpace()->block_start(p); | |
| 3247 } | |
| 3248 } | |
| 3249 return NULL; | |
| 3250 } | |
| 3251 #endif | |
| 3252 | |
| 3253 HeapWord* | |
| 3254 ConcurrentMarkSweepGeneration::expand_and_allocate(size_t word_size, | |
| 3255 bool tlab, | |
| 3256 bool parallel) { | |
|
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3257 CMSSynchronousYieldRequest yr; |
| 0 | 3258 assert(!tlab, "Can't deal with TLAB allocation"); |
| 3259 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 3260 expand(word_size*HeapWordSize, MinHeapDeltaBytes, | |
| 3261 CMSExpansionCause::_satisfy_allocation); | |
| 3262 if (GCExpandToAllocateDelayMillis > 0) { | |
| 3263 os::sleep(Thread::current(), GCExpandToAllocateDelayMillis, false); | |
| 3264 } | |
|
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3265 return have_lock_and_allocate(word_size, tlab); |
| 0 | 3266 } |
| 3267 | |
| 3268 // YSR: All of this generation expansion/shrinking stuff is an exact copy of | |
| 3269 // OneContigSpaceCardGeneration, which makes me wonder if we should move this | |
| 3270 // to CardGeneration and share it... | |
|
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3271 bool ConcurrentMarkSweepGeneration::expand(size_t bytes, size_t expand_bytes) { |
|
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3272 return CardGeneration::expand(bytes, expand_bytes); |
|
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|
3273 } |
|
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3274 |
| 0 | 3275 void ConcurrentMarkSweepGeneration::expand(size_t bytes, size_t expand_bytes, |
| 3276 CMSExpansionCause::Cause cause) | |
| 3277 { | |
|
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3278 |
|
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3279 bool success = expand(bytes, expand_bytes); |
|
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3280 |
| 0 | 3281 // remember why we expanded; this information is used |
| 3282 // by shouldConcurrentCollect() when making decisions on whether to start | |
| 3283 // a new CMS cycle. | |
| 3284 if (success) { | |
| 3285 set_expansion_cause(cause); | |
| 3286 if (PrintGCDetails && Verbose) { | |
| 3287 gclog_or_tty->print_cr("Expanded CMS gen for %s", | |
| 3288 CMSExpansionCause::to_string(cause)); | |
| 3289 } | |
| 3290 } | |
| 3291 } | |
| 3292 | |
| 3293 HeapWord* ConcurrentMarkSweepGeneration::expand_and_par_lab_allocate(CMSParGCThreadState* ps, size_t word_sz) { | |
| 3294 HeapWord* res = NULL; | |
| 3295 MutexLocker x(ParGCRareEvent_lock); | |
| 3296 while (true) { | |
| 3297 // Expansion by some other thread might make alloc OK now: | |
| 3298 res = ps->lab.alloc(word_sz); | |
| 3299 if (res != NULL) return res; | |
| 3300 // If there's not enough expansion space available, give up. | |
| 3301 if (_virtual_space.uncommitted_size() < (word_sz * HeapWordSize)) { | |
| 3302 return NULL; | |
| 3303 } | |
| 3304 // Otherwise, we try expansion. | |
| 3305 expand(word_sz*HeapWordSize, MinHeapDeltaBytes, | |
| 3306 CMSExpansionCause::_allocate_par_lab); | |
| 3307 // Now go around the loop and try alloc again; | |
| 3308 // A competing par_promote might beat us to the expansion space, | |
| 3309 // so we may go around the loop again if promotion fails agaion. | |
| 3310 if (GCExpandToAllocateDelayMillis > 0) { | |
| 3311 os::sleep(Thread::current(), GCExpandToAllocateDelayMillis, false); | |
| 3312 } | |
| 3313 } | |
| 3314 } | |
| 3315 | |
| 3316 | |
| 3317 bool ConcurrentMarkSweepGeneration::expand_and_ensure_spooling_space( | |
| 3318 PromotionInfo* promo) { | |
| 3319 MutexLocker x(ParGCRareEvent_lock); | |
| 3320 size_t refill_size_bytes = promo->refillSize() * HeapWordSize; | |
| 3321 while (true) { | |
| 3322 // Expansion by some other thread might make alloc OK now: | |
| 3323 if (promo->ensure_spooling_space()) { | |
| 3324 assert(promo->has_spooling_space(), | |
| 3325 "Post-condition of successful ensure_spooling_space()"); | |
| 3326 return true; | |
| 3327 } | |
| 3328 // If there's not enough expansion space available, give up. | |
| 3329 if (_virtual_space.uncommitted_size() < refill_size_bytes) { | |
| 3330 return false; | |
| 3331 } | |
| 3332 // Otherwise, we try expansion. | |
| 3333 expand(refill_size_bytes, MinHeapDeltaBytes, | |
| 3334 CMSExpansionCause::_allocate_par_spooling_space); | |
| 3335 // Now go around the loop and try alloc again; | |
| 3336 // A competing allocation might beat us to the expansion space, | |
| 3337 // so we may go around the loop again if allocation fails again. | |
| 3338 if (GCExpandToAllocateDelayMillis > 0) { | |
| 3339 os::sleep(Thread::current(), GCExpandToAllocateDelayMillis, false); | |
| 3340 } | |
| 3341 } | |
| 3342 } | |
| 3343 | |
| 3344 | |
| 3345 | |
| 3346 void ConcurrentMarkSweepGeneration::shrink(size_t bytes) { | |
| 3347 assert_locked_or_safepoint(Heap_lock); | |
| 3348 size_t size = ReservedSpace::page_align_size_down(bytes); | |
| 3349 if (size > 0) { | |
| 3350 shrink_by(size); | |
| 3351 } | |
| 3352 } | |
| 3353 | |
| 3354 bool ConcurrentMarkSweepGeneration::grow_by(size_t bytes) { | |
| 3355 assert_locked_or_safepoint(Heap_lock); | |
| 3356 bool result = _virtual_space.expand_by(bytes); | |
| 3357 if (result) { | |
| 3358 HeapWord* old_end = _cmsSpace->end(); | |
| 3359 size_t new_word_size = | |
| 3360 heap_word_size(_virtual_space.committed_size()); | |
| 3361 MemRegion mr(_cmsSpace->bottom(), new_word_size); | |
| 3362 _bts->resize(new_word_size); // resize the block offset shared array | |
| 3363 Universe::heap()->barrier_set()->resize_covered_region(mr); | |
| 3364 // Hmmmm... why doesn't CFLS::set_end verify locking? | |
| 3365 // This is quite ugly; FIX ME XXX | |
|
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|
3366 _cmsSpace->assert_locked(freelistLock()); |
| 0 | 3367 _cmsSpace->set_end((HeapWord*)_virtual_space.high()); |
| 3368 | |
| 3369 // update the space and generation capacity counters | |
| 3370 if (UsePerfData) { | |
| 3371 _space_counters->update_capacity(); | |
| 3372 _gen_counters->update_all(); | |
| 3373 } | |
| 3374 | |
| 3375 if (Verbose && PrintGC) { | |
| 3376 size_t new_mem_size = _virtual_space.committed_size(); | |
| 3377 size_t old_mem_size = new_mem_size - bytes; | |
| 3378 gclog_or_tty->print_cr("Expanding %s from %ldK by %ldK to %ldK", | |
| 3379 name(), old_mem_size/K, bytes/K, new_mem_size/K); | |
| 3380 } | |
| 3381 } | |
| 3382 return result; | |
| 3383 } | |
| 3384 | |
| 3385 bool ConcurrentMarkSweepGeneration::grow_to_reserved() { | |
| 3386 assert_locked_or_safepoint(Heap_lock); | |
| 3387 bool success = true; | |
| 3388 const size_t remaining_bytes = _virtual_space.uncommitted_size(); | |
| 3389 if (remaining_bytes > 0) { | |
| 3390 success = grow_by(remaining_bytes); | |
| 3391 DEBUG_ONLY(if (!success) warning("grow to reserved failed");) | |
| 3392 } | |
| 3393 return success; | |
| 3394 } | |
| 3395 | |
| 3396 void ConcurrentMarkSweepGeneration::shrink_by(size_t bytes) { | |
| 3397 assert_locked_or_safepoint(Heap_lock); | |
| 3398 assert_lock_strong(freelistLock()); | |
| 3399 // XXX Fix when compaction is implemented. | |
| 3400 warning("Shrinking of CMS not yet implemented"); | |
| 3401 return; | |
| 3402 } | |
| 3403 | |
| 3404 | |
| 3405 // Simple ctor/dtor wrapper for accounting & timer chores around concurrent | |
| 3406 // phases. | |
| 3407 class CMSPhaseAccounting: public StackObj { | |
| 3408 public: | |
| 3409 CMSPhaseAccounting(CMSCollector *collector, | |
| 3410 const char *phase, | |
| 3411 bool print_cr = true); | |
| 3412 ~CMSPhaseAccounting(); | |
| 3413 | |
| 3414 private: | |
| 3415 CMSCollector *_collector; | |
| 3416 const char *_phase; | |
| 3417 elapsedTimer _wallclock; | |
| 3418 bool _print_cr; | |
| 3419 | |
| 3420 public: | |
| 3421 // Not MT-safe; so do not pass around these StackObj's | |
| 3422 // where they may be accessed by other threads. | |
| 3423 jlong wallclock_millis() { | |
| 3424 assert(_wallclock.is_active(), "Wall clock should not stop"); | |
| 3425 _wallclock.stop(); // to record time | |
| 3426 jlong ret = _wallclock.milliseconds(); | |
| 3427 _wallclock.start(); // restart | |
| 3428 return ret; | |
| 3429 } | |
| 3430 }; | |
| 3431 | |
| 3432 CMSPhaseAccounting::CMSPhaseAccounting(CMSCollector *collector, | |
| 3433 const char *phase, | |
| 3434 bool print_cr) : | |
| 3435 _collector(collector), _phase(phase), _print_cr(print_cr) { | |
| 3436 | |
| 3437 if (PrintCMSStatistics != 0) { | |
| 3438 _collector->resetYields(); | |
| 3439 } | |
| 3440 if (PrintGCDetails && PrintGCTimeStamps) { | |
| 3441 gclog_or_tty->date_stamp(PrintGCDateStamps); | |
| 3442 gclog_or_tty->stamp(); | |
| 3443 gclog_or_tty->print_cr(": [%s-concurrent-%s-start]", | |
| 3444 _collector->cmsGen()->short_name(), _phase); | |
| 3445 } | |
| 3446 _collector->resetTimer(); | |
| 3447 _wallclock.start(); | |
| 3448 _collector->startTimer(); | |
| 3449 } | |
| 3450 | |
| 3451 CMSPhaseAccounting::~CMSPhaseAccounting() { | |
| 3452 assert(_wallclock.is_active(), "Wall clock should not have stopped"); | |
| 3453 _collector->stopTimer(); | |
| 3454 _wallclock.stop(); | |
| 3455 if (PrintGCDetails) { | |
| 3456 gclog_or_tty->date_stamp(PrintGCDateStamps); | |
| 3457 if (PrintGCTimeStamps) { | |
| 3458 gclog_or_tty->stamp(); | |
| 3459 gclog_or_tty->print(": "); | |
| 3460 } | |
| 3461 gclog_or_tty->print("[%s-concurrent-%s: %3.3f/%3.3f secs]", | |
| 3462 _collector->cmsGen()->short_name(), | |
| 3463 _phase, _collector->timerValue(), _wallclock.seconds()); | |
| 3464 if (_print_cr) { | |
| 3465 gclog_or_tty->print_cr(""); | |
| 3466 } | |
| 3467 if (PrintCMSStatistics != 0) { | |
| 3468 gclog_or_tty->print_cr(" (CMS-concurrent-%s yielded %d times)", _phase, | |
| 3469 _collector->yields()); | |
| 3470 } | |
| 3471 } | |
| 3472 } | |
| 3473 | |
| 3474 // CMS work | |
| 3475 | |
| 3476 // Checkpoint the roots into this generation from outside | |
| 3477 // this generation. [Note this initial checkpoint need only | |
| 3478 // be approximate -- we'll do a catch up phase subsequently.] | |
| 3479 void CMSCollector::checkpointRootsInitial(bool asynch) { | |
| 3480 assert(_collectorState == InitialMarking, "Wrong collector state"); | |
| 3481 check_correct_thread_executing(); | |
|
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|
3482 TraceCMSMemoryManagerStats tms(_collectorState,GenCollectedHeap::heap()->gc_cause()); |
|
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|
3483 |
| 0 | 3484 ReferenceProcessor* rp = ref_processor(); |
| 3485 SpecializationStats::clear(); | |
| 3486 assert(_restart_addr == NULL, "Control point invariant"); | |
| 3487 if (asynch) { | |
| 3488 // acquire locks for subsequent manipulations | |
| 3489 MutexLockerEx x(bitMapLock(), | |
| 3490 Mutex::_no_safepoint_check_flag); | |
| 3491 checkpointRootsInitialWork(asynch); | |
| 3492 rp->verify_no_references_recorded(); | |
| 3493 rp->enable_discovery(); // enable ("weak") refs discovery | |
| 3494 _collectorState = Marking; | |
| 3495 } else { | |
| 3496 // (Weak) Refs discovery: this is controlled from genCollectedHeap::do_collection | |
| 3497 // which recognizes if we are a CMS generation, and doesn't try to turn on | |
| 3498 // discovery; verify that they aren't meddling. | |
| 3499 assert(!rp->discovery_is_atomic(), | |
| 3500 "incorrect setting of discovery predicate"); | |
| 3501 assert(!rp->discovery_enabled(), "genCollectedHeap shouldn't control " | |
| 3502 "ref discovery for this generation kind"); | |
| 3503 // already have locks | |
| 3504 checkpointRootsInitialWork(asynch); | |
| 3505 rp->enable_discovery(); // now enable ("weak") refs discovery | |
| 3506 _collectorState = Marking; | |
| 3507 } | |
| 3508 SpecializationStats::print(); | |
| 3509 } | |
| 3510 | |
| 3511 void CMSCollector::checkpointRootsInitialWork(bool asynch) { | |
| 3512 assert(SafepointSynchronize::is_at_safepoint(), "world should be stopped"); | |
| 3513 assert(_collectorState == InitialMarking, "just checking"); | |
| 3514 | |
| 3515 // If there has not been a GC[n-1] since last GC[n] cycle completed, | |
| 3516 // precede our marking with a collection of all | |
| 3517 // younger generations to keep floating garbage to a minimum. | |
| 3518 // XXX: we won't do this for now -- it's an optimization to be done later. | |
| 3519 | |
| 3520 // already have locks | |
| 3521 assert_lock_strong(bitMapLock()); | |
| 3522 assert(_markBitMap.isAllClear(), "was reset at end of previous cycle"); | |
| 3523 | |
| 3524 // Setup the verification and class unloading state for this | |
| 3525 // CMS collection cycle. | |
| 3526 setup_cms_unloading_and_verification_state(); | |
| 3527 | |
| 3528 NOT_PRODUCT(TraceTime t("\ncheckpointRootsInitialWork", | |
| 3529 PrintGCDetails && Verbose, true, gclog_or_tty);) | |
| 3530 if (UseAdaptiveSizePolicy) { | |
| 3531 size_policy()->checkpoint_roots_initial_begin(); | |
| 3532 } | |
| 3533 | |
| 3534 // Reset all the PLAB chunk arrays if necessary. | |
| 3535 if (_survivor_plab_array != NULL && !CMSPLABRecordAlways) { | |
| 3536 reset_survivor_plab_arrays(); | |
| 3537 } | |
| 3538 | |
| 3539 ResourceMark rm; | |
| 3540 HandleMark hm; | |
| 3541 | |
| 3542 FalseClosure falseClosure; | |
| 3543 // In the case of a synchronous collection, we will elide the | |
| 3544 // remark step, so it's important to catch all the nmethod oops | |
|
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|
3545 // in this step. |
|
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3546 // The final 'true' flag to gen_process_strong_roots will ensure this. |
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3547 // If 'async' is true, we can relax the nmethod tracing. |
|
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|
3548 MarkRefsIntoClosure notOlder(_span, &_markBitMap); |
| 0 | 3549 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
| 3550 | |
| 3551 verify_work_stacks_empty(); | |
| 3552 verify_overflow_empty(); | |
| 3553 | |
| 3554 gch->ensure_parsability(false); // fill TLABs, but no need to retire them | |
| 3555 // Update the saved marks which may affect the root scans. | |
| 3556 gch->save_marks(); | |
| 3557 | |
| 3558 // weak reference processing has not started yet. | |
| 3559 ref_processor()->set_enqueuing_is_done(false); | |
| 3560 | |
| 3561 { | |
| 935 | 3562 // This is not needed. DEBUG_ONLY(RememberKlassesChecker imx(true);) |
| 0 | 3563 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact;) |
| 3564 gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel. | |
| 3565 gch->gen_process_strong_roots(_cmsGen->level(), | |
| 3566 true, // younger gens are roots | |
|
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|
3567 true, // activate StrongRootsScope |
| 0 | 3568 true, // collecting perm gen |
| 3569 SharedHeap::ScanningOption(roots_scanning_options()), | |
|
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|
3570 ¬Older, |
|
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3571 true, // walk all of code cache if (so & SO_CodeCache) |
|
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|
3572 NULL); |
| 0 | 3573 } |
| 3574 | |
| 3575 // Clear mod-union table; it will be dirtied in the prologue of | |
| 3576 // CMS generation per each younger generation collection. | |
| 3577 | |
| 3578 assert(_modUnionTable.isAllClear(), | |
| 3579 "Was cleared in most recent final checkpoint phase" | |
| 3580 " or no bits are set in the gc_prologue before the start of the next " | |
| 3581 "subsequent marking phase."); | |
| 3582 | |
| 3583 // Temporarily disabled, since pre/post-consumption closures don't | |
| 3584 // care about precleaned cards | |
| 3585 #if 0 | |
| 3586 { | |
| 3587 MemRegion mr = MemRegion((HeapWord*)_virtual_space.low(), | |
| 3588 (HeapWord*)_virtual_space.high()); | |
| 3589 _ct->ct_bs()->preclean_dirty_cards(mr); | |
| 3590 } | |
| 3591 #endif | |
| 3592 | |
| 3593 // Save the end of the used_region of the constituent generations | |
| 3594 // to be used to limit the extent of sweep in each generation. | |
| 3595 save_sweep_limits(); | |
| 3596 if (UseAdaptiveSizePolicy) { | |
| 3597 size_policy()->checkpoint_roots_initial_end(gch->gc_cause()); | |
| 3598 } | |
| 3599 verify_overflow_empty(); | |
| 3600 } | |
| 3601 | |
| 3602 bool CMSCollector::markFromRoots(bool asynch) { | |
| 3603 // we might be tempted to assert that: | |
| 3604 // assert(asynch == !SafepointSynchronize::is_at_safepoint(), | |
| 3605 // "inconsistent argument?"); | |
| 3606 // However that wouldn't be right, because it's possible that | |
| 3607 // a safepoint is indeed in progress as a younger generation | |
| 3608 // stop-the-world GC happens even as we mark in this generation. | |
| 3609 assert(_collectorState == Marking, "inconsistent state?"); | |
| 3610 check_correct_thread_executing(); | |
| 3611 verify_overflow_empty(); | |
| 3612 | |
| 3613 bool res; | |
| 3614 if (asynch) { | |
| 3615 | |
| 3616 // Start the timers for adaptive size policy for the concurrent phases | |
| 3617 // Do it here so that the foreground MS can use the concurrent | |
| 3618 // timer since a foreground MS might has the sweep done concurrently | |
| 3619 // or STW. | |
| 3620 if (UseAdaptiveSizePolicy) { | |
| 3621 size_policy()->concurrent_marking_begin(); | |
| 3622 } | |
| 3623 | |
| 3624 // Weak ref discovery note: We may be discovering weak | |
| 3625 // refs in this generation concurrent (but interleaved) with | |
| 3626 // weak ref discovery by a younger generation collector. | |
| 3627 | |
| 3628 CMSTokenSyncWithLocks ts(true, bitMapLock()); | |
| 3629 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
| 3630 CMSPhaseAccounting pa(this, "mark", !PrintGCDetails); | |
| 3631 res = markFromRootsWork(asynch); | |
| 3632 if (res) { | |
| 3633 _collectorState = Precleaning; | |
| 3634 } else { // We failed and a foreground collection wants to take over | |
| 3635 assert(_foregroundGCIsActive, "internal state inconsistency"); | |
| 3636 assert(_restart_addr == NULL, "foreground will restart from scratch"); | |
| 3637 if (PrintGCDetails) { | |
| 3638 gclog_or_tty->print_cr("bailing out to foreground collection"); | |
| 3639 } | |
| 3640 } | |
| 3641 if (UseAdaptiveSizePolicy) { | |
| 3642 size_policy()->concurrent_marking_end(); | |
| 3643 } | |
| 3644 } else { | |
| 3645 assert(SafepointSynchronize::is_at_safepoint(), | |
| 3646 "inconsistent with asynch == false"); | |
| 3647 if (UseAdaptiveSizePolicy) { | |
| 3648 size_policy()->ms_collection_marking_begin(); | |
| 3649 } | |
| 3650 // already have locks | |
| 3651 res = markFromRootsWork(asynch); | |
| 3652 _collectorState = FinalMarking; | |
| 3653 if (UseAdaptiveSizePolicy) { | |
| 3654 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 3655 size_policy()->ms_collection_marking_end(gch->gc_cause()); | |
| 3656 } | |
| 3657 } | |
| 3658 verify_overflow_empty(); | |
| 3659 return res; | |
| 3660 } | |
| 3661 | |
| 3662 bool CMSCollector::markFromRootsWork(bool asynch) { | |
| 3663 // iterate over marked bits in bit map, doing a full scan and mark | |
| 3664 // from these roots using the following algorithm: | |
| 3665 // . if oop is to the right of the current scan pointer, | |
| 3666 // mark corresponding bit (we'll process it later) | |
| 3667 // . else (oop is to left of current scan pointer) | |
| 3668 // push oop on marking stack | |
| 3669 // . drain the marking stack | |
| 3670 | |
| 3671 // Note that when we do a marking step we need to hold the | |
| 3672 // bit map lock -- recall that direct allocation (by mutators) | |
| 3673 // and promotion (by younger generation collectors) is also | |
| 3674 // marking the bit map. [the so-called allocate live policy.] | |
| 3675 // Because the implementation of bit map marking is not | |
| 3676 // robust wrt simultaneous marking of bits in the same word, | |
| 3677 // we need to make sure that there is no such interference | |
| 3678 // between concurrent such updates. | |
| 3679 | |
| 3680 // already have locks | |
| 3681 assert_lock_strong(bitMapLock()); | |
| 3682 | |
| 3683 // Clear the revisit stack, just in case there are any | |
| 3684 // obsolete contents from a short-circuited previous CMS cycle. | |
| 3685 _revisitStack.reset(); | |
| 3686 verify_work_stacks_empty(); | |
| 3687 verify_overflow_empty(); | |
| 3688 assert(_revisitStack.isEmpty(), "tabula rasa"); | |
|
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|
3689 DEBUG_ONLY(RememberKlassesChecker cmx(should_unload_classes());) |
| 0 | 3690 bool result = false; |
| 1284 | 3691 if (CMSConcurrentMTEnabled && ConcGCThreads > 0) { |
| 0 | 3692 result = do_marking_mt(asynch); |
| 3693 } else { | |
| 3694 result = do_marking_st(asynch); | |
| 3695 } | |
| 3696 return result; | |
| 3697 } | |
| 3698 | |
| 3699 // Forward decl | |
| 3700 class CMSConcMarkingTask; | |
| 3701 | |
| 3702 class CMSConcMarkingTerminator: public ParallelTaskTerminator { | |
| 3703 CMSCollector* _collector; | |
| 3704 CMSConcMarkingTask* _task; | |
|
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3705 public: |
| 0 | 3706 virtual void yield(); |
|
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|
3707 |
| 0 | 3708 // "n_threads" is the number of threads to be terminated. |
| 3709 // "queue_set" is a set of work queues of other threads. | |
| 3710 // "collector" is the CMS collector associated with this task terminator. | |
| 3711 // "yield" indicates whether we need the gang as a whole to yield. | |
|
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3712 CMSConcMarkingTerminator(int n_threads, TaskQueueSetSuper* queue_set, CMSCollector* collector) : |
| 0 | 3713 ParallelTaskTerminator(n_threads, queue_set), |
|
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|
3714 _collector(collector) { } |
|
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|
3715 |
|
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|
3716 void set_task(CMSConcMarkingTask* task) { |
|
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3717 _task = task; |
|
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|
3718 } |
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|
3719 }; |
|
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|
3720 |
|
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|
3721 class CMSConcMarkingTerminatorTerminator: public TerminatorTerminator { |
|
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|
3722 CMSConcMarkingTask* _task; |
|
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3723 public: |
|
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|
3724 bool should_exit_termination(); |
| 0 | 3725 void set_task(CMSConcMarkingTask* task) { |
| 3726 _task = task; | |
| 3727 } | |
| 3728 }; | |
| 3729 | |
| 3730 // MT Concurrent Marking Task | |
| 3731 class CMSConcMarkingTask: public YieldingFlexibleGangTask { | |
| 3732 CMSCollector* _collector; | |
| 3733 int _n_workers; // requested/desired # workers | |
| 3734 bool _asynch; | |
| 3735 bool _result; | |
| 3736 CompactibleFreeListSpace* _cms_space; | |
| 3737 CompactibleFreeListSpace* _perm_space; | |
|
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|
3738 char _pad_front[64]; // padding to ... |
|
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|
3739 HeapWord* _global_finger; // ... avoid sharing cache line |
|
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|
3740 char _pad_back[64]; |
|
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|
3741 HeapWord* _restart_addr; |
| 0 | 3742 |
| 3743 // Exposed here for yielding support | |
| 3744 Mutex* const _bit_map_lock; | |
| 3745 | |
| 3746 // The per thread work queues, available here for stealing | |
| 3747 OopTaskQueueSet* _task_queues; | |
|
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|
3748 |
|
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|
3749 // Termination (and yielding) support |
| 0 | 3750 CMSConcMarkingTerminator _term; |
|
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|
3751 CMSConcMarkingTerminatorTerminator _term_term; |
| 0 | 3752 |
| 3753 public: | |
| 3754 CMSConcMarkingTask(CMSCollector* collector, | |
| 3755 CompactibleFreeListSpace* cms_space, | |
| 3756 CompactibleFreeListSpace* perm_space, | |
|
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|
3757 bool asynch, |
| 0 | 3758 YieldingFlexibleWorkGang* workers, |
| 3759 OopTaskQueueSet* task_queues): | |
| 3760 YieldingFlexibleGangTask("Concurrent marking done multi-threaded"), | |
| 3761 _collector(collector), | |
| 3762 _cms_space(cms_space), | |
| 3763 _perm_space(perm_space), | |
|
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|
3764 _asynch(asynch), _n_workers(0), _result(true), |
|
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|
3765 _task_queues(task_queues), |
|
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|
3766 _term(_n_workers, task_queues, _collector), |
| 0 | 3767 _bit_map_lock(collector->bitMapLock()) |
| 3768 { | |
|
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|
3769 _requested_size = _n_workers; |
| 0 | 3770 _term.set_task(this); |
|
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|
3771 _term_term.set_task(this); |
| 0 | 3772 assert(_cms_space->bottom() < _perm_space->bottom(), |
| 3773 "Finger incorrectly initialized below"); | |
|
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|
3774 _restart_addr = _global_finger = _cms_space->bottom(); |
| 0 | 3775 } |
| 3776 | |
| 3777 | |
| 3778 OopTaskQueueSet* task_queues() { return _task_queues; } | |
| 3779 | |
| 3780 OopTaskQueue* work_queue(int i) { return task_queues()->queue(i); } | |
| 3781 | |
| 3782 HeapWord** global_finger_addr() { return &_global_finger; } | |
| 3783 | |
| 3784 CMSConcMarkingTerminator* terminator() { return &_term; } | |
| 3785 | |
|
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|
3786 virtual void set_for_termination(int active_workers) { |
|
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|
3787 terminator()->reset_for_reuse(active_workers); |
|
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|
3788 } |
|
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|
3789 |
| 0 | 3790 void work(int i); |
|
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|
3791 bool should_yield() { |
|
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|
3792 return ConcurrentMarkSweepThread::should_yield() |
|
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|
3793 && !_collector->foregroundGCIsActive() |
|
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|
3794 && _asynch; |
|
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|
3795 } |
| 0 | 3796 |
| 3797 virtual void coordinator_yield(); // stuff done by coordinator | |
| 3798 bool result() { return _result; } | |
| 3799 | |
| 3800 void reset(HeapWord* ra) { | |
|
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3801 assert(_global_finger >= _cms_space->end(), "Postcondition of ::work(i)"); |
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3802 assert(_global_finger >= _perm_space->end(), "Postcondition of ::work(i)"); |
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3803 assert(ra < _perm_space->end(), "ra too large"); |
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|
3804 _restart_addr = _global_finger = ra; |
| 0 | 3805 _term.reset_for_reuse(); |
| 3806 } | |
| 3807 | |
| 3808 static bool get_work_from_overflow_stack(CMSMarkStack* ovflw_stk, | |
| 3809 OopTaskQueue* work_q); | |
| 3810 | |
| 3811 private: | |
| 3812 void do_scan_and_mark(int i, CompactibleFreeListSpace* sp); | |
| 3813 void do_work_steal(int i); | |
| 3814 void bump_global_finger(HeapWord* f); | |
| 3815 }; | |
| 3816 | |
|
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|
3817 bool CMSConcMarkingTerminatorTerminator::should_exit_termination() { |
|
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|
3818 assert(_task != NULL, "Error"); |
|
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|
3819 return _task->yielding(); |
|
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|
3820 // Note that we do not need the disjunct || _task->should_yield() above |
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3821 // because we want terminating threads to yield only if the task |
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3822 // is already in the midst of yielding, which happens only after at least one |
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3823 // thread has yielded. |
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3824 } |
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3825 |
| 0 | 3826 void CMSConcMarkingTerminator::yield() { |
|
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3827 if (_task->should_yield()) { |
| 0 | 3828 _task->yield(); |
| 3829 } else { | |
| 3830 ParallelTaskTerminator::yield(); | |
| 3831 } | |
| 3832 } | |
| 3833 | |
| 3834 //////////////////////////////////////////////////////////////// | |
| 3835 // Concurrent Marking Algorithm Sketch | |
| 3836 //////////////////////////////////////////////////////////////// | |
| 3837 // Until all tasks exhausted (both spaces): | |
| 3838 // -- claim next available chunk | |
| 3839 // -- bump global finger via CAS | |
| 3840 // -- find first object that starts in this chunk | |
| 3841 // and start scanning bitmap from that position | |
| 3842 // -- scan marked objects for oops | |
| 3843 // -- CAS-mark target, and if successful: | |
| 3844 // . if target oop is above global finger (volatile read) | |
| 3845 // nothing to do | |
| 3846 // . if target oop is in chunk and above local finger | |
| 3847 // then nothing to do | |
| 3848 // . else push on work-queue | |
| 3849 // -- Deal with possible overflow issues: | |
| 3850 // . local work-queue overflow causes stuff to be pushed on | |
| 3851 // global (common) overflow queue | |
| 3852 // . always first empty local work queue | |
| 3853 // . then get a batch of oops from global work queue if any | |
| 3854 // . then do work stealing | |
| 3855 // -- When all tasks claimed (both spaces) | |
| 3856 // and local work queue empty, | |
| 3857 // then in a loop do: | |
| 3858 // . check global overflow stack; steal a batch of oops and trace | |
| 3859 // . try to steal from other threads oif GOS is empty | |
| 3860 // . if neither is available, offer termination | |
| 3861 // -- Terminate and return result | |
| 3862 // | |
| 3863 void CMSConcMarkingTask::work(int i) { | |
| 3864 elapsedTimer _timer; | |
| 3865 ResourceMark rm; | |
| 3866 HandleMark hm; | |
| 3867 | |
| 3868 DEBUG_ONLY(_collector->verify_overflow_empty();) | |
| 3869 | |
| 3870 // Before we begin work, our work queue should be empty | |
| 3871 assert(work_queue(i)->size() == 0, "Expected to be empty"); | |
| 3872 // Scan the bitmap covering _cms_space, tracing through grey objects. | |
| 3873 _timer.start(); | |
| 3874 do_scan_and_mark(i, _cms_space); | |
| 3875 _timer.stop(); | |
| 3876 if (PrintCMSStatistics != 0) { | |
| 3877 gclog_or_tty->print_cr("Finished cms space scanning in %dth thread: %3.3f sec", | |
| 3878 i, _timer.seconds()); // XXX: need xxx/xxx type of notation, two timers | |
| 3879 } | |
| 3880 | |
| 3881 // ... do the same for the _perm_space | |
| 3882 _timer.reset(); | |
| 3883 _timer.start(); | |
| 3884 do_scan_and_mark(i, _perm_space); | |
| 3885 _timer.stop(); | |
| 3886 if (PrintCMSStatistics != 0) { | |
| 3887 gclog_or_tty->print_cr("Finished perm space scanning in %dth thread: %3.3f sec", | |
| 3888 i, _timer.seconds()); // XXX: need xxx/xxx type of notation, two timers | |
| 3889 } | |
| 3890 | |
| 3891 // ... do work stealing | |
| 3892 _timer.reset(); | |
| 3893 _timer.start(); | |
| 3894 do_work_steal(i); | |
| 3895 _timer.stop(); | |
| 3896 if (PrintCMSStatistics != 0) { | |
| 3897 gclog_or_tty->print_cr("Finished work stealing in %dth thread: %3.3f sec", | |
| 3898 i, _timer.seconds()); // XXX: need xxx/xxx type of notation, two timers | |
| 3899 } | |
| 3900 assert(_collector->_markStack.isEmpty(), "Should have been emptied"); | |
| 3901 assert(work_queue(i)->size() == 0, "Should have been emptied"); | |
| 3902 // Note that under the current task protocol, the | |
| 3903 // following assertion is true even of the spaces | |
| 3904 // expanded since the completion of the concurrent | |
| 3905 // marking. XXX This will likely change under a strict | |
| 3906 // ABORT semantics. | |
| 3907 assert(_global_finger > _cms_space->end() && | |
| 3908 _global_finger >= _perm_space->end(), | |
| 3909 "All tasks have been completed"); | |
| 3910 DEBUG_ONLY(_collector->verify_overflow_empty();) | |
| 3911 } | |
| 3912 | |
| 3913 void CMSConcMarkingTask::bump_global_finger(HeapWord* f) { | |
| 3914 HeapWord* read = _global_finger; | |
| 3915 HeapWord* cur = read; | |
| 3916 while (f > read) { | |
| 3917 cur = read; | |
| 3918 read = (HeapWord*) Atomic::cmpxchg_ptr(f, &_global_finger, cur); | |
| 3919 if (cur == read) { | |
| 3920 // our cas succeeded | |
| 3921 assert(_global_finger >= f, "protocol consistency"); | |
| 3922 break; | |
| 3923 } | |
| 3924 } | |
| 3925 } | |
| 3926 | |
| 3927 // This is really inefficient, and should be redone by | |
| 3928 // using (not yet available) block-read and -write interfaces to the | |
| 3929 // stack and the work_queue. XXX FIX ME !!! | |
| 3930 bool CMSConcMarkingTask::get_work_from_overflow_stack(CMSMarkStack* ovflw_stk, | |
| 3931 OopTaskQueue* work_q) { | |
| 3932 // Fast lock-free check | |
| 3933 if (ovflw_stk->length() == 0) { | |
| 3934 return false; | |
| 3935 } | |
| 3936 assert(work_q->size() == 0, "Shouldn't steal"); | |
| 3937 MutexLockerEx ml(ovflw_stk->par_lock(), | |
| 3938 Mutex::_no_safepoint_check_flag); | |
| 3939 // Grab up to 1/4 the size of the work queue | |
|
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3940 size_t num = MIN2((size_t)(work_q->max_elems() - work_q->size())/4, |
| 0 | 3941 (size_t)ParGCDesiredObjsFromOverflowList); |
| 3942 num = MIN2(num, ovflw_stk->length()); | |
| 3943 for (int i = (int) num; i > 0; i--) { | |
| 3944 oop cur = ovflw_stk->pop(); | |
| 3945 assert(cur != NULL, "Counted wrong?"); | |
| 3946 work_q->push(cur); | |
| 3947 } | |
| 3948 return num > 0; | |
| 3949 } | |
| 3950 | |
| 3951 void CMSConcMarkingTask::do_scan_and_mark(int i, CompactibleFreeListSpace* sp) { | |
| 3952 SequentialSubTasksDone* pst = sp->conc_par_seq_tasks(); | |
| 3953 int n_tasks = pst->n_tasks(); | |
| 3954 // We allow that there may be no tasks to do here because | |
| 3955 // we are restarting after a stack overflow. | |
|
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3956 assert(pst->valid() || n_tasks == 0, "Uninitialized use?"); |
| 0 | 3957 int nth_task = 0; |
| 3958 | |
|
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3959 HeapWord* aligned_start = sp->bottom(); |
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3960 if (sp->used_region().contains(_restart_addr)) { |
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3961 // Align down to a card boundary for the start of 0th task |
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3962 // for this space. |
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3963 aligned_start = |
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3964 (HeapWord*)align_size_down((uintptr_t)_restart_addr, |
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3965 CardTableModRefBS::card_size); |
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3966 } |
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3967 |
| 0 | 3968 size_t chunk_size = sp->marking_task_size(); |
| 3969 while (!pst->is_task_claimed(/* reference */ nth_task)) { | |
| 3970 // Having claimed the nth task in this space, | |
| 3971 // compute the chunk that it corresponds to: | |
|
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3972 MemRegion span = MemRegion(aligned_start + nth_task*chunk_size, |
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3973 aligned_start + (nth_task+1)*chunk_size); |
| 0 | 3974 // Try and bump the global finger via a CAS; |
| 3975 // note that we need to do the global finger bump | |
| 3976 // _before_ taking the intersection below, because | |
| 3977 // the task corresponding to that region will be | |
| 3978 // deemed done even if the used_region() expands | |
| 3979 // because of allocation -- as it almost certainly will | |
| 3980 // during start-up while the threads yield in the | |
| 3981 // closure below. | |
| 3982 HeapWord* finger = span.end(); | |
| 3983 bump_global_finger(finger); // atomically | |
| 3984 // There are null tasks here corresponding to chunks | |
| 3985 // beyond the "top" address of the space. | |
| 3986 span = span.intersection(sp->used_region()); | |
| 3987 if (!span.is_empty()) { // Non-null task | |
|
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3988 HeapWord* prev_obj; |
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3989 assert(!span.contains(_restart_addr) || nth_task == 0, |
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3990 "Inconsistency"); |
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3991 if (nth_task == 0) { |
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3992 // For the 0th task, we'll not need to compute a block_start. |
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3993 if (span.contains(_restart_addr)) { |
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3994 // In the case of a restart because of stack overflow, |
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3995 // we might additionally skip a chunk prefix. |
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3996 prev_obj = _restart_addr; |
| 0 | 3997 } else { |
|
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3998 prev_obj = span.start(); |
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3999 } |
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4000 } else { |
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4001 // We want to skip the first object because |
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4002 // the protocol is to scan any object in its entirety |
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4003 // that _starts_ in this span; a fortiori, any |
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4004 // object starting in an earlier span is scanned |
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4005 // as part of an earlier claimed task. |
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4006 // Below we use the "careful" version of block_start |
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4007 // so we do not try to navigate uninitialized objects. |
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4008 prev_obj = sp->block_start_careful(span.start()); |
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4009 // Below we use a variant of block_size that uses the |
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4010 // Printezis bits to avoid waiting for allocated |
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4011 // objects to become initialized/parsable. |
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4012 while (prev_obj < span.start()) { |
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4013 size_t sz = sp->block_size_no_stall(prev_obj, _collector); |
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4014 if (sz > 0) { |
|
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4015 prev_obj += sz; |
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4016 } else { |
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4017 // In this case we may end up doing a bit of redundant |
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4018 // scanning, but that appears unavoidable, short of |
|
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4019 // locking the free list locks; see bug 6324141. |
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4020 break; |
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4021 } |
| 0 | 4022 } |
| 4023 } | |
| 4024 if (prev_obj < span.end()) { | |
| 4025 MemRegion my_span = MemRegion(prev_obj, span.end()); | |
| 4026 // Do the marking work within a non-empty span -- | |
| 4027 // the last argument to the constructor indicates whether the | |
| 4028 // iteration should be incremental with periodic yields. | |
| 4029 Par_MarkFromRootsClosure cl(this, _collector, my_span, | |
| 4030 &_collector->_markBitMap, | |
| 4031 work_queue(i), | |
| 4032 &_collector->_markStack, | |
| 4033 &_collector->_revisitStack, | |
| 4034 _asynch); | |
| 4035 _collector->_markBitMap.iterate(&cl, my_span.start(), my_span.end()); | |
| 4036 } // else nothing to do for this task | |
| 4037 } // else nothing to do for this task | |
| 4038 } | |
| 4039 // We'd be tempted to assert here that since there are no | |
| 4040 // more tasks left to claim in this space, the global_finger | |
| 4041 // must exceed space->top() and a fortiori space->end(). However, | |
| 4042 // that would not quite be correct because the bumping of | |
| 4043 // global_finger occurs strictly after the claiming of a task, | |
| 4044 // so by the time we reach here the global finger may not yet | |
| 4045 // have been bumped up by the thread that claimed the last | |
| 4046 // task. | |
| 4047 pst->all_tasks_completed(); | |
| 4048 } | |
| 4049 | |
| 935 | 4050 class Par_ConcMarkingClosure: public Par_KlassRememberingOopClosure { |
|
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4051 private: |
|
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4052 CMSConcMarkingTask* _task; |
| 0 | 4053 MemRegion _span; |
| 4054 CMSBitMap* _bit_map; | |
| 4055 CMSMarkStack* _overflow_stack; | |
| 4056 OopTaskQueue* _work_queue; | |
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4057 protected: |
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4058 DO_OOP_WORK_DEFN |
| 0 | 4059 public: |
|
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4060 Par_ConcMarkingClosure(CMSCollector* collector, CMSConcMarkingTask* task, OopTaskQueue* work_queue, |
| 935 | 4061 CMSBitMap* bit_map, CMSMarkStack* overflow_stack, |
| 4062 CMSMarkStack* revisit_stack): | |
| 4063 Par_KlassRememberingOopClosure(collector, NULL, revisit_stack), | |
|
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4064 _task(task), |
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4065 _span(collector->_span), |
| 0 | 4066 _work_queue(work_queue), |
| 4067 _bit_map(bit_map), | |
| 935 | 4068 _overflow_stack(overflow_stack) |
| 4069 { } | |
|
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4070 virtual void do_oop(oop* p); |
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4071 virtual void do_oop(narrowOop* p); |
| 0 | 4072 void trim_queue(size_t max); |
| 4073 void handle_stack_overflow(HeapWord* lost); | |
|
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4074 void do_yield_check() { |
|
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4075 if (_task->should_yield()) { |
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4076 _task->yield(); |
|
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4077 } |
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4078 } |
| 0 | 4079 }; |
| 4080 | |
|
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4081 // Grey object scanning during work stealing phase -- |
|
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4082 // the salient assumption here is that any references |
|
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4083 // that are in these stolen objects being scanned must |
|
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4084 // already have been initialized (else they would not have |
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4085 // been published), so we do not need to check for |
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4086 // uninitialized objects before pushing here. |
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4087 void Par_ConcMarkingClosure::do_oop(oop obj) { |
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4088 assert(obj->is_oop_or_null(true), "expected an oop or NULL"); |
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4089 HeapWord* addr = (HeapWord*)obj; |
| 0 | 4090 // Check if oop points into the CMS generation |
| 4091 // and is not marked | |
| 4092 if (_span.contains(addr) && !_bit_map->isMarked(addr)) { | |
| 4093 // a white object ... | |
| 4094 // If we manage to "claim" the object, by being the | |
| 4095 // first thread to mark it, then we push it on our | |
| 4096 // marking stack | |
| 4097 if (_bit_map->par_mark(addr)) { // ... now grey | |
| 4098 // push on work queue (grey set) | |
| 4099 bool simulate_overflow = false; | |
| 4100 NOT_PRODUCT( | |
| 4101 if (CMSMarkStackOverflowALot && | |
| 4102 _collector->simulate_overflow()) { | |
| 4103 // simulate a stack overflow | |
| 4104 simulate_overflow = true; | |
| 4105 } | |
| 4106 ) | |
| 4107 if (simulate_overflow || | |
|
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4108 !(_work_queue->push(obj) || _overflow_stack->par_push(obj))) { |
| 0 | 4109 // stack overflow |
| 4110 if (PrintCMSStatistics != 0) { | |
| 4111 gclog_or_tty->print_cr("CMS marking stack overflow (benign) at " | |
| 4112 SIZE_FORMAT, _overflow_stack->capacity()); | |
| 4113 } | |
| 4114 // We cannot assert that the overflow stack is full because | |
| 4115 // it may have been emptied since. | |
| 4116 assert(simulate_overflow || | |
| 4117 _work_queue->size() == _work_queue->max_elems(), | |
| 4118 "Else push should have succeeded"); | |
| 4119 handle_stack_overflow(addr); | |
| 4120 } | |
| 4121 } // Else, some other thread got there first | |
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4122 do_yield_check(); |
| 0 | 4123 } |
| 4124 } | |
| 4125 | |
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4126 void Par_ConcMarkingClosure::do_oop(oop* p) { Par_ConcMarkingClosure::do_oop_work(p); } |
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4127 void Par_ConcMarkingClosure::do_oop(narrowOop* p) { Par_ConcMarkingClosure::do_oop_work(p); } |
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4128 |
| 0 | 4129 void Par_ConcMarkingClosure::trim_queue(size_t max) { |
| 4130 while (_work_queue->size() > max) { | |
| 4131 oop new_oop; | |
| 4132 if (_work_queue->pop_local(new_oop)) { | |
| 4133 assert(new_oop->is_oop(), "Should be an oop"); | |
| 4134 assert(_bit_map->isMarked((HeapWord*)new_oop), "Grey object"); | |
| 4135 assert(_span.contains((HeapWord*)new_oop), "Not in span"); | |
| 4136 assert(new_oop->is_parsable(), "Should be parsable"); | |
| 4137 new_oop->oop_iterate(this); // do_oop() above | |
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4138 do_yield_check(); |
| 0 | 4139 } |
| 4140 } | |
| 4141 } | |
| 4142 | |
| 4143 // Upon stack overflow, we discard (part of) the stack, | |
| 4144 // remembering the least address amongst those discarded | |
| 4145 // in CMSCollector's _restart_address. | |
| 4146 void Par_ConcMarkingClosure::handle_stack_overflow(HeapWord* lost) { | |
| 4147 // We need to do this under a mutex to prevent other | |
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4148 // workers from interfering with the work done below. |
| 0 | 4149 MutexLockerEx ml(_overflow_stack->par_lock(), |
| 4150 Mutex::_no_safepoint_check_flag); | |
| 4151 // Remember the least grey address discarded | |
| 4152 HeapWord* ra = (HeapWord*)_overflow_stack->least_value(lost); | |
| 4153 _collector->lower_restart_addr(ra); | |
| 4154 _overflow_stack->reset(); // discard stack contents | |
| 4155 _overflow_stack->expand(); // expand the stack if possible | |
| 4156 } | |
| 4157 | |
| 4158 | |
| 4159 void CMSConcMarkingTask::do_work_steal(int i) { | |
| 4160 OopTaskQueue* work_q = work_queue(i); | |
| 4161 oop obj_to_scan; | |
| 4162 CMSBitMap* bm = &(_collector->_markBitMap); | |
| 4163 CMSMarkStack* ovflw = &(_collector->_markStack); | |
| 935 | 4164 CMSMarkStack* revisit = &(_collector->_revisitStack); |
| 0 | 4165 int* seed = _collector->hash_seed(i); |
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4166 Par_ConcMarkingClosure cl(_collector, this, work_q, bm, ovflw, revisit); |
| 0 | 4167 while (true) { |
| 4168 cl.trim_queue(0); | |
| 4169 assert(work_q->size() == 0, "Should have been emptied above"); | |
| 4170 if (get_work_from_overflow_stack(ovflw, work_q)) { | |
| 4171 // Can't assert below because the work obtained from the | |
| 4172 // overflow stack may already have been stolen from us. | |
| 4173 // assert(work_q->size() > 0, "Work from overflow stack"); | |
| 4174 continue; | |
| 4175 } else if (task_queues()->steal(i, seed, /* reference */ obj_to_scan)) { | |
| 4176 assert(obj_to_scan->is_oop(), "Should be an oop"); | |
| 4177 assert(bm->isMarked((HeapWord*)obj_to_scan), "Grey object"); | |
| 4178 obj_to_scan->oop_iterate(&cl); | |
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4179 } else if (terminator()->offer_termination(&_term_term)) { |
| 0 | 4180 assert(work_q->size() == 0, "Impossible!"); |
| 4181 break; | |
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4182 } else if (yielding() || should_yield()) { |
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4183 yield(); |
| 0 | 4184 } |
| 4185 } | |
| 4186 } | |
| 4187 | |
| 4188 // This is run by the CMS (coordinator) thread. | |
| 4189 void CMSConcMarkingTask::coordinator_yield() { | |
| 4190 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 4191 "CMS thread should hold CMS token"); | |
| 935 | 4192 DEBUG_ONLY(RememberKlassesChecker mux(false);) |
| 0 | 4193 // First give up the locks, then yield, then re-lock |
| 4194 // We should probably use a constructor/destructor idiom to | |
| 4195 // do this unlock/lock or modify the MutexUnlocker class to | |
| 4196 // serve our purpose. XXX | |
| 4197 assert_lock_strong(_bit_map_lock); | |
| 4198 _bit_map_lock->unlock(); | |
| 4199 ConcurrentMarkSweepThread::desynchronize(true); | |
| 4200 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 4201 _collector->stopTimer(); | |
| 4202 if (PrintCMSStatistics != 0) { | |
| 4203 _collector->incrementYields(); | |
| 4204 } | |
| 4205 _collector->icms_wait(); | |
| 4206 | |
| 4207 // It is possible for whichever thread initiated the yield request | |
| 4208 // not to get a chance to wake up and take the bitmap lock between | |
| 4209 // this thread releasing it and reacquiring it. So, while the | |
| 4210 // should_yield() flag is on, let's sleep for a bit to give the | |
| 4211 // other thread a chance to wake up. The limit imposed on the number | |
| 4212 // of iterations is defensive, to avoid any unforseen circumstances | |
| 4213 // putting us into an infinite loop. Since it's always been this | |
| 4214 // (coordinator_yield()) method that was observed to cause the | |
| 4215 // problem, we are using a parameter (CMSCoordinatorYieldSleepCount) | |
| 4216 // which is by default non-zero. For the other seven methods that | |
| 4217 // also perform the yield operation, as are using a different | |
| 4218 // parameter (CMSYieldSleepCount) which is by default zero. This way we | |
| 4219 // can enable the sleeping for those methods too, if necessary. | |
| 4220 // See 6442774. | |
| 4221 // | |
| 4222 // We really need to reconsider the synchronization between the GC | |
| 4223 // thread and the yield-requesting threads in the future and we | |
| 4224 // should really use wait/notify, which is the recommended | |
| 4225 // way of doing this type of interaction. Additionally, we should | |
| 4226 // consolidate the eight methods that do the yield operation and they | |
| 4227 // are almost identical into one for better maintenability and | |
| 4228 // readability. See 6445193. | |
| 4229 // | |
| 4230 // Tony 2006.06.29 | |
| 4231 for (unsigned i = 0; i < CMSCoordinatorYieldSleepCount && | |
|
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4232 ConcurrentMarkSweepThread::should_yield() && |
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4233 !CMSCollector::foregroundGCIsActive(); ++i) { |
| 0 | 4234 os::sleep(Thread::current(), 1, false); |
| 4235 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 4236 } | |
| 4237 | |
| 4238 ConcurrentMarkSweepThread::synchronize(true); | |
| 4239 _bit_map_lock->lock_without_safepoint_check(); | |
| 4240 _collector->startTimer(); | |
| 4241 } | |
| 4242 | |
| 4243 bool CMSCollector::do_marking_mt(bool asynch) { | |
| 1284 | 4244 assert(ConcGCThreads > 0 && conc_workers() != NULL, "precondition"); |
| 0 | 4245 // In the future this would be determined ergonomically, based |
| 4246 // on #cpu's, # active mutator threads (and load), and mutation rate. | |
| 1284 | 4247 int num_workers = ConcGCThreads; |
| 0 | 4248 |
| 4249 CompactibleFreeListSpace* cms_space = _cmsGen->cmsSpace(); | |
| 4250 CompactibleFreeListSpace* perm_space = _permGen->cmsSpace(); | |
| 4251 | |
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4252 CMSConcMarkingTask tsk(this, |
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4253 cms_space, |
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4254 perm_space, |
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4255 asynch, |
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4256 conc_workers(), |
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4257 task_queues()); |
| 0 | 4258 |
| 4259 // Since the actual number of workers we get may be different | |
| 4260 // from the number we requested above, do we need to do anything different | |
| 4261 // below? In particular, may be we need to subclass the SequantialSubTasksDone | |
| 4262 // class?? XXX | |
| 4263 cms_space ->initialize_sequential_subtasks_for_marking(num_workers); | |
| 4264 perm_space->initialize_sequential_subtasks_for_marking(num_workers); | |
| 4265 | |
| 4266 // Refs discovery is already non-atomic. | |
| 4267 assert(!ref_processor()->discovery_is_atomic(), "Should be non-atomic"); | |
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4268 assert(ref_processor()->discovery_is_mt(), "Discovery should be MT"); |
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4269 DEBUG_ONLY(RememberKlassesChecker cmx(should_unload_classes());) |
| 0 | 4270 conc_workers()->start_task(&tsk); |
| 4271 while (tsk.yielded()) { | |
| 4272 tsk.coordinator_yield(); | |
| 4273 conc_workers()->continue_task(&tsk); | |
| 4274 } | |
| 4275 // If the task was aborted, _restart_addr will be non-NULL | |
| 4276 assert(tsk.completed() || _restart_addr != NULL, "Inconsistency"); | |
| 4277 while (_restart_addr != NULL) { | |
| 4278 // XXX For now we do not make use of ABORTED state and have not | |
| 4279 // yet implemented the right abort semantics (even in the original | |
| 4280 // single-threaded CMS case). That needs some more investigation | |
| 4281 // and is deferred for now; see CR# TBF. 07252005YSR. XXX | |
| 4282 assert(!CMSAbortSemantics || tsk.aborted(), "Inconsistency"); | |
| 4283 // If _restart_addr is non-NULL, a marking stack overflow | |
| 605 | 4284 // occurred; we need to do a fresh marking iteration from the |
| 0 | 4285 // indicated restart address. |
| 4286 if (_foregroundGCIsActive && asynch) { | |
| 4287 // We may be running into repeated stack overflows, having | |
| 4288 // reached the limit of the stack size, while making very | |
| 4289 // slow forward progress. It may be best to bail out and | |
| 4290 // let the foreground collector do its job. | |
| 4291 // Clear _restart_addr, so that foreground GC | |
| 4292 // works from scratch. This avoids the headache of | |
| 4293 // a "rescan" which would otherwise be needed because | |
| 4294 // of the dirty mod union table & card table. | |
| 4295 _restart_addr = NULL; | |
| 4296 return false; | |
| 4297 } | |
| 4298 // Adjust the task to restart from _restart_addr | |
| 4299 tsk.reset(_restart_addr); | |
| 4300 cms_space ->initialize_sequential_subtasks_for_marking(num_workers, | |
| 4301 _restart_addr); | |
| 4302 perm_space->initialize_sequential_subtasks_for_marking(num_workers, | |
| 4303 _restart_addr); | |
| 4304 _restart_addr = NULL; | |
| 4305 // Get the workers going again | |
| 4306 conc_workers()->start_task(&tsk); | |
| 4307 while (tsk.yielded()) { | |
| 4308 tsk.coordinator_yield(); | |
| 4309 conc_workers()->continue_task(&tsk); | |
| 4310 } | |
| 4311 } | |
| 4312 assert(tsk.completed(), "Inconsistency"); | |
| 4313 assert(tsk.result() == true, "Inconsistency"); | |
| 4314 return true; | |
| 4315 } | |
| 4316 | |
| 4317 bool CMSCollector::do_marking_st(bool asynch) { | |
| 4318 ResourceMark rm; | |
| 4319 HandleMark hm; | |
| 4320 | |
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4321 // Temporarily make refs discovery single threaded (non-MT) |
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4322 ReferenceProcessorMTDiscoveryMutator rp_mut_discovery(ref_processor(), false); |
| 0 | 4323 MarkFromRootsClosure markFromRootsClosure(this, _span, &_markBitMap, |
| 4324 &_markStack, &_revisitStack, CMSYield && asynch); | |
| 4325 // the last argument to iterate indicates whether the iteration | |
| 4326 // should be incremental with periodic yields. | |
| 4327 _markBitMap.iterate(&markFromRootsClosure); | |
| 4328 // If _restart_addr is non-NULL, a marking stack overflow | |
| 605 | 4329 // occurred; we need to do a fresh iteration from the |
| 0 | 4330 // indicated restart address. |
| 4331 while (_restart_addr != NULL) { | |
| 4332 if (_foregroundGCIsActive && asynch) { | |
| 4333 // We may be running into repeated stack overflows, having | |
| 4334 // reached the limit of the stack size, while making very | |
| 4335 // slow forward progress. It may be best to bail out and | |
| 4336 // let the foreground collector do its job. | |
| 4337 // Clear _restart_addr, so that foreground GC | |
| 4338 // works from scratch. This avoids the headache of | |
| 4339 // a "rescan" which would otherwise be needed because | |
| 4340 // of the dirty mod union table & card table. | |
| 4341 _restart_addr = NULL; | |
| 4342 return false; // indicating failure to complete marking | |
| 4343 } | |
| 4344 // Deal with stack overflow: | |
| 4345 // we restart marking from _restart_addr | |
| 4346 HeapWord* ra = _restart_addr; | |
| 4347 markFromRootsClosure.reset(ra); | |
| 4348 _restart_addr = NULL; | |
| 4349 _markBitMap.iterate(&markFromRootsClosure, ra, _span.end()); | |
| 4350 } | |
| 4351 return true; | |
| 4352 } | |
| 4353 | |
| 4354 void CMSCollector::preclean() { | |
| 4355 check_correct_thread_executing(); | |
| 4356 assert(Thread::current()->is_ConcurrentGC_thread(), "Wrong thread"); | |
| 4357 verify_work_stacks_empty(); | |
| 4358 verify_overflow_empty(); | |
| 4359 _abort_preclean = false; | |
| 4360 if (CMSPrecleaningEnabled) { | |
| 4361 _eden_chunk_index = 0; | |
| 4362 size_t used = get_eden_used(); | |
| 4363 size_t capacity = get_eden_capacity(); | |
| 4364 // Don't start sampling unless we will get sufficiently | |
| 4365 // many samples. | |
| 4366 if (used < (capacity/(CMSScheduleRemarkSamplingRatio * 100) | |
| 4367 * CMSScheduleRemarkEdenPenetration)) { | |
| 4368 _start_sampling = true; | |
| 4369 } else { | |
| 4370 _start_sampling = false; | |
| 4371 } | |
| 4372 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
| 4373 CMSPhaseAccounting pa(this, "preclean", !PrintGCDetails); | |
| 4374 preclean_work(CMSPrecleanRefLists1, CMSPrecleanSurvivors1); | |
| 4375 } | |
| 4376 CMSTokenSync x(true); // is cms thread | |
| 4377 if (CMSPrecleaningEnabled) { | |
| 4378 sample_eden(); | |
| 4379 _collectorState = AbortablePreclean; | |
| 4380 } else { | |
| 4381 _collectorState = FinalMarking; | |
| 4382 } | |
| 4383 verify_work_stacks_empty(); | |
| 4384 verify_overflow_empty(); | |
| 4385 } | |
| 4386 | |
| 4387 // Try and schedule the remark such that young gen | |
| 4388 // occupancy is CMSScheduleRemarkEdenPenetration %. | |
| 4389 void CMSCollector::abortable_preclean() { | |
| 4390 check_correct_thread_executing(); | |
| 4391 assert(CMSPrecleaningEnabled, "Inconsistent control state"); | |
| 4392 assert(_collectorState == AbortablePreclean, "Inconsistent control state"); | |
| 4393 | |
| 4394 // If Eden's current occupancy is below this threshold, | |
| 4395 // immediately schedule the remark; else preclean | |
| 4396 // past the next scavenge in an effort to | |
| 4397 // schedule the pause as described avove. By choosing | |
| 4398 // CMSScheduleRemarkEdenSizeThreshold >= max eden size | |
| 4399 // we will never do an actual abortable preclean cycle. | |
| 4400 if (get_eden_used() > CMSScheduleRemarkEdenSizeThreshold) { | |
| 4401 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
| 4402 CMSPhaseAccounting pa(this, "abortable-preclean", !PrintGCDetails); | |
| 4403 // We need more smarts in the abortable preclean | |
| 4404 // loop below to deal with cases where allocation | |
| 4405 // in young gen is very very slow, and our precleaning | |
| 4406 // is running a losing race against a horde of | |
| 4407 // mutators intent on flooding us with CMS updates | |
| 4408 // (dirty cards). | |
| 4409 // One, admittedly dumb, strategy is to give up | |
| 4410 // after a certain number of abortable precleaning loops | |
| 4411 // or after a certain maximum time. We want to make | |
| 4412 // this smarter in the next iteration. | |
| 4413 // XXX FIX ME!!! YSR | |
| 4414 size_t loops = 0, workdone = 0, cumworkdone = 0, waited = 0; | |
| 4415 while (!(should_abort_preclean() || | |
| 4416 ConcurrentMarkSweepThread::should_terminate())) { | |
| 4417 workdone = preclean_work(CMSPrecleanRefLists2, CMSPrecleanSurvivors2); | |
| 4418 cumworkdone += workdone; | |
| 4419 loops++; | |
| 4420 // Voluntarily terminate abortable preclean phase if we have | |
| 4421 // been at it for too long. | |
| 4422 if ((CMSMaxAbortablePrecleanLoops != 0) && | |
| 4423 loops >= CMSMaxAbortablePrecleanLoops) { | |
| 4424 if (PrintGCDetails) { | |
| 4425 gclog_or_tty->print(" CMS: abort preclean due to loops "); | |
| 4426 } | |
| 4427 break; | |
| 4428 } | |
| 4429 if (pa.wallclock_millis() > CMSMaxAbortablePrecleanTime) { | |
| 4430 if (PrintGCDetails) { | |
| 4431 gclog_or_tty->print(" CMS: abort preclean due to time "); | |
| 4432 } | |
| 4433 break; | |
| 4434 } | |
| 4435 // If we are doing little work each iteration, we should | |
| 4436 // take a short break. | |
| 4437 if (workdone < CMSAbortablePrecleanMinWorkPerIteration) { | |
| 4438 // Sleep for some time, waiting for work to accumulate | |
| 4439 stopTimer(); | |
| 4440 cmsThread()->wait_on_cms_lock(CMSAbortablePrecleanWaitMillis); | |
| 4441 startTimer(); | |
| 4442 waited++; | |
| 4443 } | |
| 4444 } | |
| 4445 if (PrintCMSStatistics > 0) { | |
| 4446 gclog_or_tty->print(" [%d iterations, %d waits, %d cards)] ", | |
| 4447 loops, waited, cumworkdone); | |
| 4448 } | |
| 4449 } | |
| 4450 CMSTokenSync x(true); // is cms thread | |
| 4451 if (_collectorState != Idling) { | |
| 4452 assert(_collectorState == AbortablePreclean, | |
| 4453 "Spontaneous state transition?"); | |
| 4454 _collectorState = FinalMarking; | |
| 4455 } // Else, a foreground collection completed this CMS cycle. | |
| 4456 return; | |
| 4457 } | |
| 4458 | |
| 4459 // Respond to an Eden sampling opportunity | |
| 4460 void CMSCollector::sample_eden() { | |
| 4461 // Make sure a young gc cannot sneak in between our | |
| 4462 // reading and recording of a sample. | |
| 4463 assert(Thread::current()->is_ConcurrentGC_thread(), | |
| 4464 "Only the cms thread may collect Eden samples"); | |
| 4465 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 4466 "Should collect samples while holding CMS token"); | |
| 4467 if (!_start_sampling) { | |
| 4468 return; | |
| 4469 } | |
| 4470 if (_eden_chunk_array) { | |
| 4471 if (_eden_chunk_index < _eden_chunk_capacity) { | |
| 4472 _eden_chunk_array[_eden_chunk_index] = *_top_addr; // take sample | |
| 4473 assert(_eden_chunk_array[_eden_chunk_index] <= *_end_addr, | |
| 4474 "Unexpected state of Eden"); | |
| 4475 // We'd like to check that what we just sampled is an oop-start address; | |
| 4476 // however, we cannot do that here since the object may not yet have been | |
| 4477 // initialized. So we'll instead do the check when we _use_ this sample | |
| 4478 // later. | |
| 4479 if (_eden_chunk_index == 0 || | |
| 4480 (pointer_delta(_eden_chunk_array[_eden_chunk_index], | |
| 4481 _eden_chunk_array[_eden_chunk_index-1]) | |
| 4482 >= CMSSamplingGrain)) { | |
| 4483 _eden_chunk_index++; // commit sample | |
| 4484 } | |
| 4485 } | |
| 4486 } | |
| 4487 if ((_collectorState == AbortablePreclean) && !_abort_preclean) { | |
| 4488 size_t used = get_eden_used(); | |
| 4489 size_t capacity = get_eden_capacity(); | |
| 4490 assert(used <= capacity, "Unexpected state of Eden"); | |
| 4491 if (used > (capacity/100 * CMSScheduleRemarkEdenPenetration)) { | |
| 4492 _abort_preclean = true; | |
| 4493 } | |
| 4494 } | |
| 4495 } | |
| 4496 | |
| 4497 | |
| 4498 size_t CMSCollector::preclean_work(bool clean_refs, bool clean_survivor) { | |
| 4499 assert(_collectorState == Precleaning || | |
| 4500 _collectorState == AbortablePreclean, "incorrect state"); | |
| 4501 ResourceMark rm; | |
| 4502 HandleMark hm; | |
|
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4503 |
|
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4504 // Precleaning is currently not MT but the reference processor |
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4505 // may be set for MT. Disable it temporarily here. |
|
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4506 ReferenceProcessor* rp = ref_processor(); |
|
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4507 ReferenceProcessorMTDiscoveryMutator rp_mut_discovery(rp, false); |
|
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4508 |
| 0 | 4509 // Do one pass of scrubbing the discovered reference lists |
| 4510 // to remove any reference objects with strongly-reachable | |
| 4511 // referents. | |
| 4512 if (clean_refs) { | |
| 4513 CMSPrecleanRefsYieldClosure yield_cl(this); | |
| 4514 assert(rp->span().equals(_span), "Spans should be equal"); | |
| 4515 CMSKeepAliveClosure keep_alive(this, _span, &_markBitMap, | |
| 935 | 4516 &_markStack, &_revisitStack, |
| 4517 true /* preclean */); | |
| 0 | 4518 CMSDrainMarkingStackClosure complete_trace(this, |
|
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4519 _span, &_markBitMap, &_markStack, |
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|
4520 &keep_alive, true /* preclean */); |
| 0 | 4521 |
| 4522 // We don't want this step to interfere with a young | |
| 4523 // collection because we don't want to take CPU | |
| 4524 // or memory bandwidth away from the young GC threads | |
| 4525 // (which may be as many as there are CPUs). | |
| 4526 // Note that we don't need to protect ourselves from | |
| 4527 // interference with mutators because they can't | |
| 4528 // manipulate the discovered reference lists nor affect | |
| 4529 // the computed reachability of the referents, the | |
| 4530 // only properties manipulated by the precleaning | |
| 4531 // of these reference lists. | |
| 4532 stopTimer(); | |
| 4533 CMSTokenSyncWithLocks x(true /* is cms thread */, | |
| 4534 bitMapLock()); | |
| 4535 startTimer(); | |
| 4536 sample_eden(); | |
| 935 | 4537 |
| 0 | 4538 // The following will yield to allow foreground |
| 4539 // collection to proceed promptly. XXX YSR: | |
| 4540 // The code in this method may need further | |
| 4541 // tweaking for better performance and some restructuring | |
| 4542 // for cleaner interfaces. | |
| 4543 rp->preclean_discovered_references( | |
| 4544 rp->is_alive_non_header(), &keep_alive, &complete_trace, | |
|
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|
4545 &yield_cl, should_unload_classes()); |
| 0 | 4546 } |
| 4547 | |
| 4548 if (clean_survivor) { // preclean the active survivor space(s) | |
| 4549 assert(_young_gen->kind() == Generation::DefNew || | |
| 4550 _young_gen->kind() == Generation::ParNew || | |
| 4551 _young_gen->kind() == Generation::ASParNew, | |
| 4552 "incorrect type for cast"); | |
| 4553 DefNewGeneration* dng = (DefNewGeneration*)_young_gen; | |
| 4554 PushAndMarkClosure pam_cl(this, _span, ref_processor(), | |
| 4555 &_markBitMap, &_modUnionTable, | |
| 4556 &_markStack, &_revisitStack, | |
| 4557 true /* precleaning phase */); | |
| 4558 stopTimer(); | |
| 4559 CMSTokenSyncWithLocks ts(true /* is cms thread */, | |
| 4560 bitMapLock()); | |
| 4561 startTimer(); | |
| 4562 unsigned int before_count = | |
| 4563 GenCollectedHeap::heap()->total_collections(); | |
| 4564 SurvivorSpacePrecleanClosure | |
| 4565 sss_cl(this, _span, &_markBitMap, &_markStack, | |
| 4566 &pam_cl, before_count, CMSYield); | |
|
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4567 DEBUG_ONLY(RememberKlassesChecker mx(should_unload_classes());) |
| 0 | 4568 dng->from()->object_iterate_careful(&sss_cl); |
| 4569 dng->to()->object_iterate_careful(&sss_cl); | |
| 4570 } | |
| 4571 MarkRefsIntoAndScanClosure | |
| 4572 mrias_cl(_span, ref_processor(), &_markBitMap, &_modUnionTable, | |
| 4573 &_markStack, &_revisitStack, this, CMSYield, | |
| 4574 true /* precleaning phase */); | |
| 4575 // CAUTION: The following closure has persistent state that may need to | |
| 4576 // be reset upon a decrease in the sequence of addresses it | |
| 4577 // processes. | |
| 4578 ScanMarkedObjectsAgainCarefullyClosure | |
| 4579 smoac_cl(this, _span, | |
| 4580 &_markBitMap, &_markStack, &_revisitStack, &mrias_cl, CMSYield); | |
| 4581 | |
| 4582 // Preclean dirty cards in ModUnionTable and CardTable using | |
| 4583 // appropriate convergence criterion; | |
| 4584 // repeat CMSPrecleanIter times unless we find that | |
| 4585 // we are losing. | |
| 4586 assert(CMSPrecleanIter < 10, "CMSPrecleanIter is too large"); | |
| 4587 assert(CMSPrecleanNumerator < CMSPrecleanDenominator, | |
| 4588 "Bad convergence multiplier"); | |
| 4589 assert(CMSPrecleanThreshold >= 100, | |
| 4590 "Unreasonably low CMSPrecleanThreshold"); | |
| 4591 | |
| 4592 size_t numIter, cumNumCards, lastNumCards, curNumCards; | |
| 4593 for (numIter = 0, cumNumCards = lastNumCards = curNumCards = 0; | |
| 4594 numIter < CMSPrecleanIter; | |
| 4595 numIter++, lastNumCards = curNumCards, cumNumCards += curNumCards) { | |
| 4596 curNumCards = preclean_mod_union_table(_cmsGen, &smoac_cl); | |
| 4597 if (CMSPermGenPrecleaningEnabled) { | |
| 4598 curNumCards += preclean_mod_union_table(_permGen, &smoac_cl); | |
| 4599 } | |
| 4600 if (Verbose && PrintGCDetails) { | |
| 4601 gclog_or_tty->print(" (modUnionTable: %d cards)", curNumCards); | |
| 4602 } | |
| 4603 // Either there are very few dirty cards, so re-mark | |
| 4604 // pause will be small anyway, or our pre-cleaning isn't | |
| 4605 // that much faster than the rate at which cards are being | |
| 4606 // dirtied, so we might as well stop and re-mark since | |
| 4607 // precleaning won't improve our re-mark time by much. | |
| 4608 if (curNumCards <= CMSPrecleanThreshold || | |
| 4609 (numIter > 0 && | |
| 4610 (curNumCards * CMSPrecleanDenominator > | |
| 4611 lastNumCards * CMSPrecleanNumerator))) { | |
| 4612 numIter++; | |
| 4613 cumNumCards += curNumCards; | |
| 4614 break; | |
| 4615 } | |
| 4616 } | |
| 4617 curNumCards = preclean_card_table(_cmsGen, &smoac_cl); | |
| 4618 if (CMSPermGenPrecleaningEnabled) { | |
| 4619 curNumCards += preclean_card_table(_permGen, &smoac_cl); | |
| 4620 } | |
| 4621 cumNumCards += curNumCards; | |
| 4622 if (PrintGCDetails && PrintCMSStatistics != 0) { | |
| 4623 gclog_or_tty->print_cr(" (cardTable: %d cards, re-scanned %d cards, %d iterations)", | |
| 4624 curNumCards, cumNumCards, numIter); | |
| 4625 } | |
| 4626 return cumNumCards; // as a measure of useful work done | |
| 4627 } | |
| 4628 | |
| 4629 // PRECLEANING NOTES: | |
| 4630 // Precleaning involves: | |
| 4631 // . reading the bits of the modUnionTable and clearing the set bits. | |
| 4632 // . For the cards corresponding to the set bits, we scan the | |
| 4633 // objects on those cards. This means we need the free_list_lock | |
| 4634 // so that we can safely iterate over the CMS space when scanning | |
| 4635 // for oops. | |
| 4636 // . When we scan the objects, we'll be both reading and setting | |
| 4637 // marks in the marking bit map, so we'll need the marking bit map. | |
| 4638 // . For protecting _collector_state transitions, we take the CGC_lock. | |
| 4639 // Note that any races in the reading of of card table entries by the | |
| 4640 // CMS thread on the one hand and the clearing of those entries by the | |
| 4641 // VM thread or the setting of those entries by the mutator threads on the | |
| 4642 // other are quite benign. However, for efficiency it makes sense to keep | |
| 4643 // the VM thread from racing with the CMS thread while the latter is | |
| 4644 // dirty card info to the modUnionTable. We therefore also use the | |
| 4645 // CGC_lock to protect the reading of the card table and the mod union | |
| 4646 // table by the CM thread. | |
| 4647 // . We run concurrently with mutator updates, so scanning | |
| 4648 // needs to be done carefully -- we should not try to scan | |
| 4649 // potentially uninitialized objects. | |
| 4650 // | |
| 4651 // Locking strategy: While holding the CGC_lock, we scan over and | |
| 4652 // reset a maximal dirty range of the mod union / card tables, then lock | |
| 4653 // the free_list_lock and bitmap lock to do a full marking, then | |
| 4654 // release these locks; and repeat the cycle. This allows for a | |
| 4655 // certain amount of fairness in the sharing of these locks between | |
| 4656 // the CMS collector on the one hand, and the VM thread and the | |
| 4657 // mutators on the other. | |
| 4658 | |
| 4659 // NOTE: preclean_mod_union_table() and preclean_card_table() | |
| 4660 // further below are largely identical; if you need to modify | |
| 4661 // one of these methods, please check the other method too. | |
| 4662 | |
| 4663 size_t CMSCollector::preclean_mod_union_table( | |
| 4664 ConcurrentMarkSweepGeneration* gen, | |
| 4665 ScanMarkedObjectsAgainCarefullyClosure* cl) { | |
| 4666 verify_work_stacks_empty(); | |
| 4667 verify_overflow_empty(); | |
| 4668 | |
| 935 | 4669 // Turn off checking for this method but turn it back on |
| 4670 // selectively. There are yield points in this method | |
| 4671 // but it is difficult to turn the checking off just around | |
| 4672 // the yield points. It is simpler to selectively turn | |
| 4673 // it on. | |
| 4674 DEBUG_ONLY(RememberKlassesChecker mux(false);) | |
| 4675 | |
| 0 | 4676 // strategy: starting with the first card, accumulate contiguous |
| 4677 // ranges of dirty cards; clear these cards, then scan the region | |
| 4678 // covered by these cards. | |
| 4679 | |
| 4680 // Since all of the MUT is committed ahead, we can just use | |
| 4681 // that, in case the generations expand while we are precleaning. | |
| 4682 // It might also be fine to just use the committed part of the | |
| 4683 // generation, but we might potentially miss cards when the | |
| 4684 // generation is rapidly expanding while we are in the midst | |
| 4685 // of precleaning. | |
| 4686 HeapWord* startAddr = gen->reserved().start(); | |
| 4687 HeapWord* endAddr = gen->reserved().end(); | |
| 4688 | |
| 4689 cl->setFreelistLock(gen->freelistLock()); // needed for yielding | |
| 4690 | |
| 4691 size_t numDirtyCards, cumNumDirtyCards; | |
| 4692 HeapWord *nextAddr, *lastAddr; | |
| 4693 for (cumNumDirtyCards = numDirtyCards = 0, | |
| 4694 nextAddr = lastAddr = startAddr; | |
| 4695 nextAddr < endAddr; | |
| 4696 nextAddr = lastAddr, cumNumDirtyCards += numDirtyCards) { | |
| 4697 | |
| 4698 ResourceMark rm; | |
| 4699 HandleMark hm; | |
| 4700 | |
| 4701 MemRegion dirtyRegion; | |
| 4702 { | |
| 4703 stopTimer(); | |
| 935 | 4704 // Potential yield point |
| 0 | 4705 CMSTokenSync ts(true); |
| 4706 startTimer(); | |
| 4707 sample_eden(); | |
| 4708 // Get dirty region starting at nextOffset (inclusive), | |
| 4709 // simultaneously clearing it. | |
| 4710 dirtyRegion = | |
| 4711 _modUnionTable.getAndClearMarkedRegion(nextAddr, endAddr); | |
| 4712 assert(dirtyRegion.start() >= nextAddr, | |
| 4713 "returned region inconsistent?"); | |
| 4714 } | |
| 4715 // Remember where the next search should begin. | |
| 4716 // The returned region (if non-empty) is a right open interval, | |
| 4717 // so lastOffset is obtained from the right end of that | |
| 4718 // interval. | |
| 4719 lastAddr = dirtyRegion.end(); | |
| 4720 // Should do something more transparent and less hacky XXX | |
| 4721 numDirtyCards = | |
| 4722 _modUnionTable.heapWordDiffToOffsetDiff(dirtyRegion.word_size()); | |
| 4723 | |
| 4724 // We'll scan the cards in the dirty region (with periodic | |
| 4725 // yields for foreground GC as needed). | |
| 4726 if (!dirtyRegion.is_empty()) { | |
| 4727 assert(numDirtyCards > 0, "consistency check"); | |
| 4728 HeapWord* stop_point = NULL; | |
|
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4729 stopTimer(); |
| 935 | 4730 // Potential yield point |
|
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4731 CMSTokenSyncWithLocks ts(true, gen->freelistLock(), |
|
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|
4732 bitMapLock()); |
|
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|
4733 startTimer(); |
| 0 | 4734 { |
| 4735 verify_work_stacks_empty(); | |
| 4736 verify_overflow_empty(); | |
| 4737 sample_eden(); | |
|
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4738 DEBUG_ONLY(RememberKlassesChecker mx(should_unload_classes());) |
| 0 | 4739 stop_point = |
| 4740 gen->cmsSpace()->object_iterate_careful_m(dirtyRegion, cl); | |
| 4741 } | |
| 4742 if (stop_point != NULL) { | |
| 4743 // The careful iteration stopped early either because it found an | |
| 4744 // uninitialized object, or because we were in the midst of an | |
| 4745 // "abortable preclean", which should now be aborted. Redirty | |
| 4746 // the bits corresponding to the partially-scanned or unscanned | |
| 4747 // cards. We'll either restart at the next block boundary or | |
| 4748 // abort the preclean. | |
| 4749 assert((CMSPermGenPrecleaningEnabled && (gen == _permGen)) || | |
| 4750 (_collectorState == AbortablePreclean && should_abort_preclean()), | |
| 4751 "Unparsable objects should only be in perm gen."); | |
| 4752 _modUnionTable.mark_range(MemRegion(stop_point, dirtyRegion.end())); | |
| 4753 if (should_abort_preclean()) { | |
| 4754 break; // out of preclean loop | |
| 4755 } else { | |
| 4756 // Compute the next address at which preclean should pick up; | |
| 4757 // might need bitMapLock in order to read P-bits. | |
| 4758 lastAddr = next_card_start_after_block(stop_point); | |
| 4759 } | |
| 4760 } | |
| 4761 } else { | |
| 4762 assert(lastAddr == endAddr, "consistency check"); | |
| 4763 assert(numDirtyCards == 0, "consistency check"); | |
| 4764 break; | |
| 4765 } | |
| 4766 } | |
| 4767 verify_work_stacks_empty(); | |
| 4768 verify_overflow_empty(); | |
| 4769 return cumNumDirtyCards; | |
| 4770 } | |
| 4771 | |
| 4772 // NOTE: preclean_mod_union_table() above and preclean_card_table() | |
| 4773 // below are largely identical; if you need to modify | |
| 4774 // one of these methods, please check the other method too. | |
| 4775 | |
| 4776 size_t CMSCollector::preclean_card_table(ConcurrentMarkSweepGeneration* gen, | |
| 4777 ScanMarkedObjectsAgainCarefullyClosure* cl) { | |
| 4778 // strategy: it's similar to precleamModUnionTable above, in that | |
| 4779 // we accumulate contiguous ranges of dirty cards, mark these cards | |
| 4780 // precleaned, then scan the region covered by these cards. | |
| 4781 HeapWord* endAddr = (HeapWord*)(gen->_virtual_space.high()); | |
| 4782 HeapWord* startAddr = (HeapWord*)(gen->_virtual_space.low()); | |
| 4783 | |
| 4784 cl->setFreelistLock(gen->freelistLock()); // needed for yielding | |
| 4785 | |
| 4786 size_t numDirtyCards, cumNumDirtyCards; | |
| 4787 HeapWord *lastAddr, *nextAddr; | |
| 4788 | |
| 4789 for (cumNumDirtyCards = numDirtyCards = 0, | |
| 4790 nextAddr = lastAddr = startAddr; | |
| 4791 nextAddr < endAddr; | |
| 4792 nextAddr = lastAddr, cumNumDirtyCards += numDirtyCards) { | |
| 4793 | |
| 4794 ResourceMark rm; | |
| 4795 HandleMark hm; | |
| 4796 | |
| 4797 MemRegion dirtyRegion; | |
| 4798 { | |
| 4799 // See comments in "Precleaning notes" above on why we | |
| 4800 // do this locking. XXX Could the locking overheads be | |
| 4801 // too high when dirty cards are sparse? [I don't think so.] | |
| 4802 stopTimer(); | |
| 4803 CMSTokenSync x(true); // is cms thread | |
| 4804 startTimer(); | |
| 4805 sample_eden(); | |
| 4806 // Get and clear dirty region from card table | |
|
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4807 dirtyRegion = _ct->ct_bs()->dirty_card_range_after_reset( |
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4808 MemRegion(nextAddr, endAddr), |
|
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4809 true, |
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4810 CardTableModRefBS::precleaned_card_val()); |
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4811 |
| 0 | 4812 assert(dirtyRegion.start() >= nextAddr, |
| 4813 "returned region inconsistent?"); | |
| 4814 } | |
| 4815 lastAddr = dirtyRegion.end(); | |
| 4816 numDirtyCards = | |
| 4817 dirtyRegion.word_size()/CardTableModRefBS::card_size_in_words; | |
| 4818 | |
| 4819 if (!dirtyRegion.is_empty()) { | |
| 4820 stopTimer(); | |
| 4821 CMSTokenSyncWithLocks ts(true, gen->freelistLock(), bitMapLock()); | |
| 4822 startTimer(); | |
| 4823 sample_eden(); | |
| 4824 verify_work_stacks_empty(); | |
| 4825 verify_overflow_empty(); | |
|
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4826 DEBUG_ONLY(RememberKlassesChecker mx(should_unload_classes());) |
| 0 | 4827 HeapWord* stop_point = |
| 4828 gen->cmsSpace()->object_iterate_careful_m(dirtyRegion, cl); | |
| 4829 if (stop_point != NULL) { | |
| 4830 // The careful iteration stopped early because it found an | |
| 4831 // uninitialized object. Redirty the bits corresponding to the | |
| 4832 // partially-scanned or unscanned cards, and start again at the | |
| 4833 // next block boundary. | |
| 4834 assert(CMSPermGenPrecleaningEnabled || | |
| 4835 (_collectorState == AbortablePreclean && should_abort_preclean()), | |
| 4836 "Unparsable objects should only be in perm gen."); | |
| 4837 _ct->ct_bs()->invalidate(MemRegion(stop_point, dirtyRegion.end())); | |
| 4838 if (should_abort_preclean()) { | |
| 4839 break; // out of preclean loop | |
| 4840 } else { | |
| 4841 // Compute the next address at which preclean should pick up. | |
| 4842 lastAddr = next_card_start_after_block(stop_point); | |
| 4843 } | |
| 4844 } | |
| 4845 } else { | |
| 4846 break; | |
| 4847 } | |
| 4848 } | |
| 4849 verify_work_stacks_empty(); | |
| 4850 verify_overflow_empty(); | |
| 4851 return cumNumDirtyCards; | |
| 4852 } | |
| 4853 | |
| 4854 void CMSCollector::checkpointRootsFinal(bool asynch, | |
| 4855 bool clear_all_soft_refs, bool init_mark_was_synchronous) { | |
| 4856 assert(_collectorState == FinalMarking, "incorrect state transition?"); | |
| 4857 check_correct_thread_executing(); | |
| 4858 // world is stopped at this checkpoint | |
| 4859 assert(SafepointSynchronize::is_at_safepoint(), | |
| 4860 "world should be stopped"); | |
|
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4861 TraceCMSMemoryManagerStats tms(_collectorState,GenCollectedHeap::heap()->gc_cause()); |
|
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|
4862 |
| 0 | 4863 verify_work_stacks_empty(); |
| 4864 verify_overflow_empty(); | |
| 4865 | |
| 4866 SpecializationStats::clear(); | |
| 4867 if (PrintGCDetails) { | |
| 4868 gclog_or_tty->print("[YG occupancy: "SIZE_FORMAT" K ("SIZE_FORMAT" K)]", | |
| 4869 _young_gen->used() / K, | |
| 4870 _young_gen->capacity() / K); | |
| 4871 } | |
| 4872 if (asynch) { | |
| 4873 if (CMSScavengeBeforeRemark) { | |
| 4874 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 4875 // Temporarily set flag to false, GCH->do_collection will | |
| 4876 // expect it to be false and set to true | |
| 4877 FlagSetting fl(gch->_is_gc_active, false); | |
| 4878 NOT_PRODUCT(TraceTime t("Scavenge-Before-Remark", | |
| 4879 PrintGCDetails && Verbose, true, gclog_or_tty);) | |
| 4880 int level = _cmsGen->level() - 1; | |
| 4881 if (level >= 0) { | |
| 4882 gch->do_collection(true, // full (i.e. force, see below) | |
| 4883 false, // !clear_all_soft_refs | |
| 4884 0, // size | |
| 4885 false, // is_tlab | |
| 4886 level // max_level | |
| 4887 ); | |
| 4888 } | |
| 4889 } | |
| 4890 FreelistLocker x(this); | |
| 4891 MutexLockerEx y(bitMapLock(), | |
| 4892 Mutex::_no_safepoint_check_flag); | |
| 4893 assert(!init_mark_was_synchronous, "but that's impossible!"); | |
| 4894 checkpointRootsFinalWork(asynch, clear_all_soft_refs, false); | |
| 4895 } else { | |
| 4896 // already have all the locks | |
| 4897 checkpointRootsFinalWork(asynch, clear_all_soft_refs, | |
| 4898 init_mark_was_synchronous); | |
| 4899 } | |
| 4900 verify_work_stacks_empty(); | |
| 4901 verify_overflow_empty(); | |
| 4902 SpecializationStats::print(); | |
| 4903 } | |
| 4904 | |
| 4905 void CMSCollector::checkpointRootsFinalWork(bool asynch, | |
| 4906 bool clear_all_soft_refs, bool init_mark_was_synchronous) { | |
| 4907 | |
| 4908 NOT_PRODUCT(TraceTime tr("checkpointRootsFinalWork", PrintGCDetails, false, gclog_or_tty);) | |
| 4909 | |
| 4910 assert(haveFreelistLocks(), "must have free list locks"); | |
| 4911 assert_lock_strong(bitMapLock()); | |
| 4912 | |
| 4913 if (UseAdaptiveSizePolicy) { | |
| 4914 size_policy()->checkpoint_roots_final_begin(); | |
| 4915 } | |
| 4916 | |
| 4917 ResourceMark rm; | |
| 4918 HandleMark hm; | |
| 4919 | |
| 4920 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 4921 | |
|
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4922 if (should_unload_classes()) { |
| 0 | 4923 CodeCache::gc_prologue(); |
| 4924 } | |
| 4925 assert(haveFreelistLocks(), "must have free list locks"); | |
| 4926 assert_lock_strong(bitMapLock()); | |
| 4927 | |
|
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|
4928 DEBUG_ONLY(RememberKlassesChecker fmx(should_unload_classes());) |
| 0 | 4929 if (!init_mark_was_synchronous) { |
| 4930 // We might assume that we need not fill TLAB's when | |
| 4931 // CMSScavengeBeforeRemark is set, because we may have just done | |
| 4932 // a scavenge which would have filled all TLAB's -- and besides | |
| 4933 // Eden would be empty. This however may not always be the case -- | |
| 4934 // for instance although we asked for a scavenge, it may not have | |
| 4935 // happened because of a JNI critical section. We probably need | |
| 4936 // a policy for deciding whether we can in that case wait until | |
| 4937 // the critical section releases and then do the remark following | |
| 4938 // the scavenge, and skip it here. In the absence of that policy, | |
| 4939 // or of an indication of whether the scavenge did indeed occur, | |
| 4940 // we cannot rely on TLAB's having been filled and must do | |
| 4941 // so here just in case a scavenge did not happen. | |
| 4942 gch->ensure_parsability(false); // fill TLAB's, but no need to retire them | |
| 4943 // Update the saved marks which may affect the root scans. | |
| 4944 gch->save_marks(); | |
| 4945 | |
| 4946 { | |
| 4947 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact;) | |
| 4948 | |
| 4949 // Note on the role of the mod union table: | |
| 4950 // Since the marker in "markFromRoots" marks concurrently with | |
| 4951 // mutators, it is possible for some reachable objects not to have been | |
| 4952 // scanned. For instance, an only reference to an object A was | |
| 4953 // placed in object B after the marker scanned B. Unless B is rescanned, | |
| 4954 // A would be collected. Such updates to references in marked objects | |
| 4955 // are detected via the mod union table which is the set of all cards | |
| 4956 // dirtied since the first checkpoint in this GC cycle and prior to | |
| 4957 // the most recent young generation GC, minus those cleaned up by the | |
| 4958 // concurrent precleaning. | |
|
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4959 if (CMSParallelRemarkEnabled && CollectedHeap::use_parallel_gc_threads()) { |
| 0 | 4960 TraceTime t("Rescan (parallel) ", PrintGCDetails, false, gclog_or_tty); |
| 4961 do_remark_parallel(); | |
| 4962 } else { | |
| 4963 TraceTime t("Rescan (non-parallel) ", PrintGCDetails, false, | |
| 4964 gclog_or_tty); | |
| 4965 do_remark_non_parallel(); | |
| 4966 } | |
| 4967 } | |
| 4968 } else { | |
| 4969 assert(!asynch, "Can't have init_mark_was_synchronous in asynch mode"); | |
| 4970 // The initial mark was stop-world, so there's no rescanning to | |
| 4971 // do; go straight on to the next step below. | |
| 4972 } | |
| 4973 verify_work_stacks_empty(); | |
| 4974 verify_overflow_empty(); | |
| 4975 | |
| 4976 { | |
| 4977 NOT_PRODUCT(TraceTime ts("refProcessingWork", PrintGCDetails, false, gclog_or_tty);) | |
| 4978 refProcessingWork(asynch, clear_all_soft_refs); | |
| 4979 } | |
| 4980 verify_work_stacks_empty(); | |
| 4981 verify_overflow_empty(); | |
| 4982 | |
|
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4983 if (should_unload_classes()) { |
| 0 | 4984 CodeCache::gc_epilogue(); |
| 4985 } | |
|
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4986 JvmtiExport::gc_epilogue(); |
| 0 | 4987 |
| 4988 // If we encountered any (marking stack / work queue) overflow | |
| 4989 // events during the current CMS cycle, take appropriate | |
| 4990 // remedial measures, where possible, so as to try and avoid | |
| 4991 // recurrence of that condition. | |
| 4992 assert(_markStack.isEmpty(), "No grey objects"); | |
| 4993 size_t ser_ovflw = _ser_pmc_remark_ovflw + _ser_pmc_preclean_ovflw + | |
|
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|
4994 _ser_kac_ovflw + _ser_kac_preclean_ovflw; |
| 0 | 4995 if (ser_ovflw > 0) { |
| 4996 if (PrintCMSStatistics != 0) { | |
| 4997 gclog_or_tty->print_cr("Marking stack overflow (benign) " | |
|
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4998 "(pmc_pc="SIZE_FORMAT", pmc_rm="SIZE_FORMAT", kac="SIZE_FORMAT |
|
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|
4999 ", kac_preclean="SIZE_FORMAT")", |
| 0 | 5000 _ser_pmc_preclean_ovflw, _ser_pmc_remark_ovflw, |
|
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|
5001 _ser_kac_ovflw, _ser_kac_preclean_ovflw); |
| 0 | 5002 } |
| 5003 _markStack.expand(); | |
| 5004 _ser_pmc_remark_ovflw = 0; | |
| 5005 _ser_pmc_preclean_ovflw = 0; | |
|
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|
5006 _ser_kac_preclean_ovflw = 0; |
| 0 | 5007 _ser_kac_ovflw = 0; |
| 5008 } | |
| 5009 if (_par_pmc_remark_ovflw > 0 || _par_kac_ovflw > 0) { | |
| 5010 if (PrintCMSStatistics != 0) { | |
| 5011 gclog_or_tty->print_cr("Work queue overflow (benign) " | |
| 5012 "(pmc_rm="SIZE_FORMAT", kac="SIZE_FORMAT")", | |
| 5013 _par_pmc_remark_ovflw, _par_kac_ovflw); | |
| 5014 } | |
| 5015 _par_pmc_remark_ovflw = 0; | |
| 5016 _par_kac_ovflw = 0; | |
| 5017 } | |
| 5018 if (PrintCMSStatistics != 0) { | |
| 5019 if (_markStack._hit_limit > 0) { | |
| 5020 gclog_or_tty->print_cr(" (benign) Hit max stack size limit ("SIZE_FORMAT")", | |
| 5021 _markStack._hit_limit); | |
| 5022 } | |
| 5023 if (_markStack._failed_double > 0) { | |
| 5024 gclog_or_tty->print_cr(" (benign) Failed stack doubling ("SIZE_FORMAT")," | |
| 5025 " current capacity "SIZE_FORMAT, | |
| 5026 _markStack._failed_double, | |
| 5027 _markStack.capacity()); | |
| 5028 } | |
| 5029 } | |
| 5030 _markStack._hit_limit = 0; | |
| 5031 _markStack._failed_double = 0; | |
| 5032 | |
| 935 | 5033 // Check that all the klasses have been checked |
| 5034 assert(_revisitStack.isEmpty(), "Not all klasses revisited"); | |
| 5035 | |
| 0 | 5036 if ((VerifyAfterGC || VerifyDuringGC) && |
| 5037 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
| 5038 verify_after_remark(); | |
| 5039 } | |
| 5040 | |
| 5041 // Change under the freelistLocks. | |
| 5042 _collectorState = Sweeping; | |
| 5043 // Call isAllClear() under bitMapLock | |
| 5044 assert(_modUnionTable.isAllClear(), "Should be clear by end of the" | |
| 5045 " final marking"); | |
| 5046 if (UseAdaptiveSizePolicy) { | |
| 5047 size_policy()->checkpoint_roots_final_end(gch->gc_cause()); | |
| 5048 } | |
| 5049 } | |
| 5050 | |
| 5051 // Parallel remark task | |
| 5052 class CMSParRemarkTask: public AbstractGangTask { | |
| 5053 CMSCollector* _collector; | |
| 5054 int _n_workers; | |
| 5055 CompactibleFreeListSpace* _cms_space; | |
| 5056 CompactibleFreeListSpace* _perm_space; | |
| 5057 | |
| 5058 // The per-thread work queues, available here for stealing. | |
| 5059 OopTaskQueueSet* _task_queues; | |
| 5060 ParallelTaskTerminator _term; | |
| 5061 | |
| 5062 public: | |
| 5063 CMSParRemarkTask(CMSCollector* collector, | |
| 5064 CompactibleFreeListSpace* cms_space, | |
| 5065 CompactibleFreeListSpace* perm_space, | |
|
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5066 int n_workers, FlexibleWorkGang* workers, |
| 0 | 5067 OopTaskQueueSet* task_queues): |
| 5068 AbstractGangTask("Rescan roots and grey objects in parallel"), | |
| 5069 _collector(collector), | |
| 5070 _cms_space(cms_space), _perm_space(perm_space), | |
| 5071 _n_workers(n_workers), | |
| 5072 _task_queues(task_queues), | |
|
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|
5073 _term(n_workers, task_queues) { } |
| 0 | 5074 |
| 5075 OopTaskQueueSet* task_queues() { return _task_queues; } | |
| 5076 | |
| 5077 OopTaskQueue* work_queue(int i) { return task_queues()->queue(i); } | |
| 5078 | |
| 5079 ParallelTaskTerminator* terminator() { return &_term; } | |
|
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|
5080 int n_workers() { return _n_workers; } |
| 0 | 5081 |
| 5082 void work(int i); | |
| 5083 | |
| 5084 private: | |
| 5085 // Work method in support of parallel rescan ... of young gen spaces | |
| 5086 void do_young_space_rescan(int i, Par_MarkRefsIntoAndScanClosure* cl, | |
| 5087 ContiguousSpace* space, | |
| 5088 HeapWord** chunk_array, size_t chunk_top); | |
| 5089 | |
| 5090 // ... of dirty cards in old space | |
| 5091 void do_dirty_card_rescan_tasks(CompactibleFreeListSpace* sp, int i, | |
| 5092 Par_MarkRefsIntoAndScanClosure* cl); | |
| 5093 | |
| 5094 // ... work stealing for the above | |
| 5095 void do_work_steal(int i, Par_MarkRefsIntoAndScanClosure* cl, int* seed); | |
| 5096 }; | |
| 5097 | |
|
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5098 // work_queue(i) is passed to the closure |
|
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|
5099 // Par_MarkRefsIntoAndScanClosure. The "i" parameter |
|
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5100 // also is passed to do_dirty_card_rescan_tasks() and to |
|
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5101 // do_work_steal() to select the i-th task_queue. |
|
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|
5102 |
| 0 | 5103 void CMSParRemarkTask::work(int i) { |
| 5104 elapsedTimer _timer; | |
| 5105 ResourceMark rm; | |
| 5106 HandleMark hm; | |
| 5107 | |
| 5108 // ---------- rescan from roots -------------- | |
| 5109 _timer.start(); | |
| 5110 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 5111 Par_MarkRefsIntoAndScanClosure par_mrias_cl(_collector, | |
| 5112 _collector->_span, _collector->ref_processor(), | |
| 5113 &(_collector->_markBitMap), | |
| 5114 work_queue(i), &(_collector->_revisitStack)); | |
| 5115 | |
| 5116 // Rescan young gen roots first since these are likely | |
| 5117 // coarsely partitioned and may, on that account, constitute | |
| 5118 // the critical path; thus, it's best to start off that | |
| 5119 // work first. | |
| 5120 // ---------- young gen roots -------------- | |
| 5121 { | |
| 5122 DefNewGeneration* dng = _collector->_young_gen->as_DefNewGeneration(); | |
| 5123 EdenSpace* eden_space = dng->eden(); | |
| 5124 ContiguousSpace* from_space = dng->from(); | |
| 5125 ContiguousSpace* to_space = dng->to(); | |
| 5126 | |
| 5127 HeapWord** eca = _collector->_eden_chunk_array; | |
| 5128 size_t ect = _collector->_eden_chunk_index; | |
| 5129 HeapWord** sca = _collector->_survivor_chunk_array; | |
| 5130 size_t sct = _collector->_survivor_chunk_index; | |
| 5131 | |
| 5132 assert(ect <= _collector->_eden_chunk_capacity, "out of bounds"); | |
| 5133 assert(sct <= _collector->_survivor_chunk_capacity, "out of bounds"); | |
| 5134 | |
| 5135 do_young_space_rescan(i, &par_mrias_cl, to_space, NULL, 0); | |
| 5136 do_young_space_rescan(i, &par_mrias_cl, from_space, sca, sct); | |
| 5137 do_young_space_rescan(i, &par_mrias_cl, eden_space, eca, ect); | |
| 5138 | |
| 5139 _timer.stop(); | |
| 5140 if (PrintCMSStatistics != 0) { | |
| 5141 gclog_or_tty->print_cr( | |
| 5142 "Finished young gen rescan work in %dth thread: %3.3f sec", | |
| 5143 i, _timer.seconds()); | |
| 5144 } | |
| 5145 } | |
| 5146 | |
| 5147 // ---------- remaining roots -------------- | |
| 5148 _timer.reset(); | |
| 5149 _timer.start(); | |
| 5150 gch->gen_process_strong_roots(_collector->_cmsGen->level(), | |
| 5151 false, // yg was scanned above | |
|
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|
5152 false, // this is parallel code |
| 0 | 5153 true, // collecting perm gen |
| 5154 SharedHeap::ScanningOption(_collector->CMSCollector::roots_scanning_options()), | |
|
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|
5155 &par_mrias_cl, |
|
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|
5156 true, // walk all of code cache if (so & SO_CodeCache) |
|
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|
5157 NULL); |
|
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|
5158 assert(_collector->should_unload_classes() |
|
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diff
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|
5159 || (_collector->CMSCollector::roots_scanning_options() & SharedHeap::SO_CodeCache), |
|
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|
5160 "if we didn't scan the code cache, we have to be ready to drop nmethods with expired weak oops"); |
| 0 | 5161 _timer.stop(); |
| 5162 if (PrintCMSStatistics != 0) { | |
| 5163 gclog_or_tty->print_cr( | |
| 5164 "Finished remaining root rescan work in %dth thread: %3.3f sec", | |
| 5165 i, _timer.seconds()); | |
| 5166 } | |
| 5167 | |
| 5168 // ---------- rescan dirty cards ------------ | |
| 5169 _timer.reset(); | |
| 5170 _timer.start(); | |
| 5171 | |
| 5172 // Do the rescan tasks for each of the two spaces | |
| 5173 // (cms_space and perm_space) in turn. | |
|
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|
5174 // "i" is passed to select the "i-th" task_queue |
| 0 | 5175 do_dirty_card_rescan_tasks(_cms_space, i, &par_mrias_cl); |
| 5176 do_dirty_card_rescan_tasks(_perm_space, i, &par_mrias_cl); | |
| 5177 _timer.stop(); | |
| 5178 if (PrintCMSStatistics != 0) { | |
| 5179 gclog_or_tty->print_cr( | |
| 5180 "Finished dirty card rescan work in %dth thread: %3.3f sec", | |
| 5181 i, _timer.seconds()); | |
| 5182 } | |
| 5183 | |
| 5184 // ---------- steal work from other threads ... | |
| 5185 // ---------- ... and drain overflow list. | |
| 5186 _timer.reset(); | |
| 5187 _timer.start(); | |
| 5188 do_work_steal(i, &par_mrias_cl, _collector->hash_seed(i)); | |
| 5189 _timer.stop(); | |
| 5190 if (PrintCMSStatistics != 0) { | |
| 5191 gclog_or_tty->print_cr( | |
| 5192 "Finished work stealing in %dth thread: %3.3f sec", | |
| 5193 i, _timer.seconds()); | |
| 5194 } | |
| 5195 } | |
| 5196 | |
|
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|
5197 // Note that parameter "i" is not used. |
| 0 | 5198 void |
| 5199 CMSParRemarkTask::do_young_space_rescan(int i, | |
| 5200 Par_MarkRefsIntoAndScanClosure* cl, ContiguousSpace* space, | |
| 5201 HeapWord** chunk_array, size_t chunk_top) { | |
| 5202 // Until all tasks completed: | |
| 5203 // . claim an unclaimed task | |
| 5204 // . compute region boundaries corresponding to task claimed | |
| 5205 // using chunk_array | |
| 5206 // . par_oop_iterate(cl) over that region | |
| 5207 | |
| 5208 ResourceMark rm; | |
| 5209 HandleMark hm; | |
| 5210 | |
| 5211 SequentialSubTasksDone* pst = space->par_seq_tasks(); | |
| 5212 assert(pst->valid(), "Uninitialized use?"); | |
| 5213 | |
| 5214 int nth_task = 0; | |
| 5215 int n_tasks = pst->n_tasks(); | |
| 5216 | |
| 5217 HeapWord *start, *end; | |
| 5218 while (!pst->is_task_claimed(/* reference */ nth_task)) { | |
| 5219 // We claimed task # nth_task; compute its boundaries. | |
| 5220 if (chunk_top == 0) { // no samples were taken | |
| 5221 assert(nth_task == 0 && n_tasks == 1, "Can have only 1 EdenSpace task"); | |
| 5222 start = space->bottom(); | |
| 5223 end = space->top(); | |
| 5224 } else if (nth_task == 0) { | |
| 5225 start = space->bottom(); | |
| 5226 end = chunk_array[nth_task]; | |
| 5227 } else if (nth_task < (jint)chunk_top) { | |
| 5228 assert(nth_task >= 1, "Control point invariant"); | |
| 5229 start = chunk_array[nth_task - 1]; | |
| 5230 end = chunk_array[nth_task]; | |
| 5231 } else { | |
| 5232 assert(nth_task == (jint)chunk_top, "Control point invariant"); | |
| 5233 start = chunk_array[chunk_top - 1]; | |
| 5234 end = space->top(); | |
| 5235 } | |
| 5236 MemRegion mr(start, end); | |
| 5237 // Verify that mr is in space | |
| 5238 assert(mr.is_empty() || space->used_region().contains(mr), | |
| 5239 "Should be in space"); | |
| 5240 // Verify that "start" is an object boundary | |
| 5241 assert(mr.is_empty() || oop(mr.start())->is_oop(), | |
| 5242 "Should be an oop"); | |
| 5243 space->par_oop_iterate(mr, cl); | |
| 5244 } | |
| 5245 pst->all_tasks_completed(); | |
| 5246 } | |
| 5247 | |
| 5248 void | |
| 5249 CMSParRemarkTask::do_dirty_card_rescan_tasks( | |
| 5250 CompactibleFreeListSpace* sp, int i, | |
| 5251 Par_MarkRefsIntoAndScanClosure* cl) { | |
| 5252 // Until all tasks completed: | |
| 5253 // . claim an unclaimed task | |
| 5254 // . compute region boundaries corresponding to task claimed | |
| 5255 // . transfer dirty bits ct->mut for that region | |
| 5256 // . apply rescanclosure to dirty mut bits for that region | |
| 5257 | |
| 5258 ResourceMark rm; | |
| 5259 HandleMark hm; | |
| 5260 | |
| 5261 OopTaskQueue* work_q = work_queue(i); | |
| 5262 ModUnionClosure modUnionClosure(&(_collector->_modUnionTable)); | |
| 5263 // CAUTION! CAUTION! CAUTION! CAUTION! CAUTION! CAUTION! CAUTION! | |
| 5264 // CAUTION: This closure has state that persists across calls to | |
| 5265 // the work method dirty_range_iterate_clear() in that it has | |
| 5266 // imbedded in it a (subtype of) UpwardsObjectClosure. The | |
| 5267 // use of that state in the imbedded UpwardsObjectClosure instance | |
| 5268 // assumes that the cards are always iterated (even if in parallel | |
| 5269 // by several threads) in monotonically increasing order per each | |
| 5270 // thread. This is true of the implementation below which picks | |
| 5271 // card ranges (chunks) in monotonically increasing order globally | |
| 5272 // and, a-fortiori, in monotonically increasing order per thread | |
| 5273 // (the latter order being a subsequence of the former). | |
| 5274 // If the work code below is ever reorganized into a more chaotic | |
| 5275 // work-partitioning form than the current "sequential tasks" | |
| 5276 // paradigm, the use of that persistent state will have to be | |
| 5277 // revisited and modified appropriately. See also related | |
| 5278 // bug 4756801 work on which should examine this code to make | |
| 5279 // sure that the changes there do not run counter to the | |
| 5280 // assumptions made here and necessary for correctness and | |
| 5281 // efficiency. Note also that this code might yield inefficient | |
| 5282 // behaviour in the case of very large objects that span one or | |
| 5283 // more work chunks. Such objects would potentially be scanned | |
| 5284 // several times redundantly. Work on 4756801 should try and | |
| 5285 // address that performance anomaly if at all possible. XXX | |
| 5286 MemRegion full_span = _collector->_span; | |
| 5287 CMSBitMap* bm = &(_collector->_markBitMap); // shared | |
| 5288 CMSMarkStack* rs = &(_collector->_revisitStack); // shared | |
| 5289 MarkFromDirtyCardsClosure | |
| 5290 greyRescanClosure(_collector, full_span, // entire span of interest | |
| 5291 sp, bm, work_q, rs, cl); | |
| 5292 | |
| 5293 SequentialSubTasksDone* pst = sp->conc_par_seq_tasks(); | |
| 5294 assert(pst->valid(), "Uninitialized use?"); | |
| 5295 int nth_task = 0; | |
| 5296 const int alignment = CardTableModRefBS::card_size * BitsPerWord; | |
| 5297 MemRegion span = sp->used_region(); | |
| 5298 HeapWord* start_addr = span.start(); | |
| 5299 HeapWord* end_addr = (HeapWord*)round_to((intptr_t)span.end(), | |
| 5300 alignment); | |
| 5301 const size_t chunk_size = sp->rescan_task_size(); // in HeapWord units | |
| 5302 assert((HeapWord*)round_to((intptr_t)start_addr, alignment) == | |
| 5303 start_addr, "Check alignment"); | |
| 5304 assert((size_t)round_to((intptr_t)chunk_size, alignment) == | |
| 5305 chunk_size, "Check alignment"); | |
| 5306 | |
| 5307 while (!pst->is_task_claimed(/* reference */ nth_task)) { | |
| 5308 // Having claimed the nth_task, compute corresponding mem-region, | |
| 5309 // which is a-fortiori aligned correctly (i.e. at a MUT bopundary). | |
| 5310 // The alignment restriction ensures that we do not need any | |
| 5311 // synchronization with other gang-workers while setting or | |
| 5312 // clearing bits in thus chunk of the MUT. | |
| 5313 MemRegion this_span = MemRegion(start_addr + nth_task*chunk_size, | |
| 5314 start_addr + (nth_task+1)*chunk_size); | |
| 5315 // The last chunk's end might be way beyond end of the | |
| 5316 // used region. In that case pull back appropriately. | |
| 5317 if (this_span.end() > end_addr) { | |
| 5318 this_span.set_end(end_addr); | |
| 5319 assert(!this_span.is_empty(), "Program logic (calculation of n_tasks)"); | |
| 5320 } | |
| 5321 // Iterate over the dirty cards covering this chunk, marking them | |
| 5322 // precleaned, and setting the corresponding bits in the mod union | |
| 5323 // table. Since we have been careful to partition at Card and MUT-word | |
| 5324 // boundaries no synchronization is needed between parallel threads. | |
| 5325 _collector->_ct->ct_bs()->dirty_card_iterate(this_span, | |
| 5326 &modUnionClosure); | |
| 5327 | |
| 5328 // Having transferred these marks into the modUnionTable, | |
| 5329 // rescan the marked objects on the dirty cards in the modUnionTable. | |
| 5330 // Even if this is at a synchronous collection, the initial marking | |
| 5331 // may have been done during an asynchronous collection so there | |
| 5332 // may be dirty bits in the mod-union table. | |
| 5333 _collector->_modUnionTable.dirty_range_iterate_clear( | |
| 5334 this_span, &greyRescanClosure); | |
| 5335 _collector->_modUnionTable.verifyNoOneBitsInRange( | |
| 5336 this_span.start(), | |
| 5337 this_span.end()); | |
| 5338 } | |
| 5339 pst->all_tasks_completed(); // declare that i am done | |
| 5340 } | |
| 5341 | |
| 5342 // . see if we can share work_queues with ParNew? XXX | |
| 5343 void | |
| 5344 CMSParRemarkTask::do_work_steal(int i, Par_MarkRefsIntoAndScanClosure* cl, | |
| 5345 int* seed) { | |
| 5346 OopTaskQueue* work_q = work_queue(i); | |
| 5347 NOT_PRODUCT(int num_steals = 0;) | |
| 5348 oop obj_to_scan; | |
| 5349 CMSBitMap* bm = &(_collector->_markBitMap); | |
| 5350 | |
| 5351 while (true) { | |
| 5352 // Completely finish any left over work from (an) earlier round(s) | |
| 5353 cl->trim_queue(0); | |
|
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5354 size_t num_from_overflow_list = MIN2((size_t)(work_q->max_elems() - work_q->size())/4, |
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5355 (size_t)ParGCDesiredObjsFromOverflowList); |
| 0 | 5356 // Now check if there's any work in the overflow list |
|
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5357 // Passing ParallelGCThreads as the third parameter, no_of_gc_threads, |
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5358 // only affects the number of attempts made to get work from the |
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5359 // overflow list and does not affect the number of workers. Just |
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5360 // pass ParallelGCThreads so this behavior is unchanged. |
| 0 | 5361 if (_collector->par_take_from_overflow_list(num_from_overflow_list, |
|
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5362 work_q, |
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5363 ParallelGCThreads)) { |
| 0 | 5364 // found something in global overflow list; |
| 5365 // not yet ready to go stealing work from others. | |
| 5366 // We'd like to assert(work_q->size() != 0, ...) | |
| 5367 // because we just took work from the overflow list, | |
| 5368 // but of course we can't since all of that could have | |
| 5369 // been already stolen from us. | |
| 5370 // "He giveth and He taketh away." | |
| 5371 continue; | |
| 5372 } | |
| 5373 // Verify that we have no work before we resort to stealing | |
| 5374 assert(work_q->size() == 0, "Have work, shouldn't steal"); | |
| 5375 // Try to steal from other queues that have work | |
| 5376 if (task_queues()->steal(i, seed, /* reference */ obj_to_scan)) { | |
| 5377 NOT_PRODUCT(num_steals++;) | |
| 5378 assert(obj_to_scan->is_oop(), "Oops, not an oop!"); | |
| 5379 assert(bm->isMarked((HeapWord*)obj_to_scan), "Stole an unmarked oop?"); | |
| 5380 // Do scanning work | |
| 5381 obj_to_scan->oop_iterate(cl); | |
| 5382 // Loop around, finish this work, and try to steal some more | |
| 5383 } else if (terminator()->offer_termination()) { | |
| 5384 break; // nirvana from the infinite cycle | |
| 5385 } | |
| 5386 } | |
| 5387 NOT_PRODUCT( | |
| 5388 if (PrintCMSStatistics != 0) { | |
| 5389 gclog_or_tty->print("\n\t(%d: stole %d oops)", i, num_steals); | |
| 5390 } | |
| 5391 ) | |
| 5392 assert(work_q->size() == 0 && _collector->overflow_list_is_empty(), | |
| 5393 "Else our work is not yet done"); | |
| 5394 } | |
| 5395 | |
| 5396 // Return a thread-local PLAB recording array, as appropriate. | |
| 5397 void* CMSCollector::get_data_recorder(int thr_num) { | |
| 5398 if (_survivor_plab_array != NULL && | |
| 5399 (CMSPLABRecordAlways || | |
| 5400 (_collectorState > Marking && _collectorState < FinalMarking))) { | |
| 5401 assert(thr_num < (int)ParallelGCThreads, "thr_num is out of bounds"); | |
| 5402 ChunkArray* ca = &_survivor_plab_array[thr_num]; | |
| 5403 ca->reset(); // clear it so that fresh data is recorded | |
| 5404 return (void*) ca; | |
| 5405 } else { | |
| 5406 return NULL; | |
| 5407 } | |
| 5408 } | |
| 5409 | |
| 5410 // Reset all the thread-local PLAB recording arrays | |
| 5411 void CMSCollector::reset_survivor_plab_arrays() { | |
| 5412 for (uint i = 0; i < ParallelGCThreads; i++) { | |
| 5413 _survivor_plab_array[i].reset(); | |
| 5414 } | |
| 5415 } | |
| 5416 | |
| 5417 // Merge the per-thread plab arrays into the global survivor chunk | |
| 5418 // array which will provide the partitioning of the survivor space | |
| 5419 // for CMS rescan. | |
|
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5420 void CMSCollector::merge_survivor_plab_arrays(ContiguousSpace* surv, |
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5421 int no_of_gc_threads) { |
| 0 | 5422 assert(_survivor_plab_array != NULL, "Error"); |
| 5423 assert(_survivor_chunk_array != NULL, "Error"); | |
| 5424 assert(_collectorState == FinalMarking, "Error"); | |
|
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5425 for (int j = 0; j < no_of_gc_threads; j++) { |
| 0 | 5426 _cursor[j] = 0; |
| 5427 } | |
| 5428 HeapWord* top = surv->top(); | |
| 5429 size_t i; | |
| 5430 for (i = 0; i < _survivor_chunk_capacity; i++) { // all sca entries | |
| 5431 HeapWord* min_val = top; // Higher than any PLAB address | |
| 5432 uint min_tid = 0; // position of min_val this round | |
|
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5433 for (int j = 0; j < no_of_gc_threads; j++) { |
| 0 | 5434 ChunkArray* cur_sca = &_survivor_plab_array[j]; |
| 5435 if (_cursor[j] == cur_sca->end()) { | |
| 5436 continue; | |
| 5437 } | |
| 5438 assert(_cursor[j] < cur_sca->end(), "ctl pt invariant"); | |
| 5439 HeapWord* cur_val = cur_sca->nth(_cursor[j]); | |
| 5440 assert(surv->used_region().contains(cur_val), "Out of bounds value"); | |
| 5441 if (cur_val < min_val) { | |
| 5442 min_tid = j; | |
| 5443 min_val = cur_val; | |
| 5444 } else { | |
| 5445 assert(cur_val < top, "All recorded addresses should be less"); | |
| 5446 } | |
| 5447 } | |
| 5448 // At this point min_val and min_tid are respectively | |
| 5449 // the least address in _survivor_plab_array[j]->nth(_cursor[j]) | |
| 5450 // and the thread (j) that witnesses that address. | |
| 5451 // We record this address in the _survivor_chunk_array[i] | |
| 5452 // and increment _cursor[min_tid] prior to the next round i. | |
| 5453 if (min_val == top) { | |
| 5454 break; | |
| 5455 } | |
| 5456 _survivor_chunk_array[i] = min_val; | |
| 5457 _cursor[min_tid]++; | |
| 5458 } | |
| 5459 // We are all done; record the size of the _survivor_chunk_array | |
| 5460 _survivor_chunk_index = i; // exclusive: [0, i) | |
| 5461 if (PrintCMSStatistics > 0) { | |
| 5462 gclog_or_tty->print(" (Survivor:" SIZE_FORMAT "chunks) ", i); | |
| 5463 } | |
| 5464 // Verify that we used up all the recorded entries | |
| 5465 #ifdef ASSERT | |
| 5466 size_t total = 0; | |
|
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5467 for (int j = 0; j < no_of_gc_threads; j++) { |
| 0 | 5468 assert(_cursor[j] == _survivor_plab_array[j].end(), "Ctl pt invariant"); |
| 5469 total += _cursor[j]; | |
| 5470 } | |
| 5471 assert(total == _survivor_chunk_index, "Ctl Pt Invariant"); | |
| 5472 // Check that the merged array is in sorted order | |
| 5473 if (total > 0) { | |
| 5474 for (size_t i = 0; i < total - 1; i++) { | |
| 5475 if (PrintCMSStatistics > 0) { | |
| 5476 gclog_or_tty->print(" (chunk" SIZE_FORMAT ":" INTPTR_FORMAT ") ", | |
| 5477 i, _survivor_chunk_array[i]); | |
| 5478 } | |
| 5479 assert(_survivor_chunk_array[i] < _survivor_chunk_array[i+1], | |
| 5480 "Not sorted"); | |
| 5481 } | |
| 5482 } | |
| 5483 #endif // ASSERT | |
| 5484 } | |
| 5485 | |
| 5486 // Set up the space's par_seq_tasks structure for work claiming | |
| 5487 // for parallel rescan of young gen. | |
| 5488 // See ParRescanTask where this is currently used. | |
| 5489 void | |
| 5490 CMSCollector:: | |
| 5491 initialize_sequential_subtasks_for_young_gen_rescan(int n_threads) { | |
| 5492 assert(n_threads > 0, "Unexpected n_threads argument"); | |
| 5493 DefNewGeneration* dng = (DefNewGeneration*)_young_gen; | |
| 5494 | |
| 5495 // Eden space | |
| 5496 { | |
| 5497 SequentialSubTasksDone* pst = dng->eden()->par_seq_tasks(); | |
| 5498 assert(!pst->valid(), "Clobbering existing data?"); | |
| 5499 // Each valid entry in [0, _eden_chunk_index) represents a task. | |
| 5500 size_t n_tasks = _eden_chunk_index + 1; | |
| 5501 assert(n_tasks == 1 || _eden_chunk_array != NULL, "Error"); | |
|
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5502 // Sets the condition for completion of the subtask (how many threads |
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5503 // need to finish in order to be done). |
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5504 pst->set_n_threads(n_threads); |
| 0 | 5505 pst->set_n_tasks((int)n_tasks); |
| 5506 } | |
| 5507 | |
| 5508 // Merge the survivor plab arrays into _survivor_chunk_array | |
| 5509 if (_survivor_plab_array != NULL) { | |
|
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5510 merge_survivor_plab_arrays(dng->from(), n_threads); |
| 0 | 5511 } else { |
| 5512 assert(_survivor_chunk_index == 0, "Error"); | |
| 5513 } | |
| 5514 | |
| 5515 // To space | |
| 5516 { | |
| 5517 SequentialSubTasksDone* pst = dng->to()->par_seq_tasks(); | |
| 5518 assert(!pst->valid(), "Clobbering existing data?"); | |
|
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5519 // Sets the condition for completion of the subtask (how many threads |
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5520 // need to finish in order to be done). |
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5521 pst->set_n_threads(n_threads); |
| 0 | 5522 pst->set_n_tasks(1); |
| 5523 assert(pst->valid(), "Error"); | |
| 5524 } | |
| 5525 | |
| 5526 // From space | |
| 5527 { | |
| 5528 SequentialSubTasksDone* pst = dng->from()->par_seq_tasks(); | |
| 5529 assert(!pst->valid(), "Clobbering existing data?"); | |
| 5530 size_t n_tasks = _survivor_chunk_index + 1; | |
| 5531 assert(n_tasks == 1 || _survivor_chunk_array != NULL, "Error"); | |
|
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5532 // Sets the condition for completion of the subtask (how many threads |
|
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5533 // need to finish in order to be done). |
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5534 pst->set_n_threads(n_threads); |
| 0 | 5535 pst->set_n_tasks((int)n_tasks); |
| 5536 assert(pst->valid(), "Error"); | |
| 5537 } | |
| 5538 } | |
| 5539 | |
| 5540 // Parallel version of remark | |
| 5541 void CMSCollector::do_remark_parallel() { | |
| 5542 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
|
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5543 FlexibleWorkGang* workers = gch->workers(); |
| 0 | 5544 assert(workers != NULL, "Need parallel worker threads."); |
| 5545 int n_workers = workers->total_workers(); | |
| 5546 CompactibleFreeListSpace* cms_space = _cmsGen->cmsSpace(); | |
| 5547 CompactibleFreeListSpace* perm_space = _permGen->cmsSpace(); | |
| 5548 | |
| 5549 CMSParRemarkTask tsk(this, | |
| 5550 cms_space, perm_space, | |
| 5551 n_workers, workers, task_queues()); | |
| 5552 | |
| 5553 // Set up for parallel process_strong_roots work. | |
| 5554 gch->set_par_threads(n_workers); | |
| 5555 // We won't be iterating over the cards in the card table updating | |
| 5556 // the younger_gen cards, so we shouldn't call the following else | |
| 5557 // the verification code as well as subsequent younger_refs_iterate | |
| 5558 // code would get confused. XXX | |
| 5559 // gch->rem_set()->prepare_for_younger_refs_iterate(true); // parallel | |
| 5560 | |
| 5561 // The young gen rescan work will not be done as part of | |
| 5562 // process_strong_roots (which currently doesn't knw how to | |
| 5563 // parallelize such a scan), but rather will be broken up into | |
| 5564 // a set of parallel tasks (via the sampling that the [abortable] | |
| 5565 // preclean phase did of EdenSpace, plus the [two] tasks of | |
| 5566 // scanning the [two] survivor spaces. Further fine-grain | |
| 5567 // parallelization of the scanning of the survivor spaces | |
| 5568 // themselves, and of precleaning of the younger gen itself | |
| 5569 // is deferred to the future. | |
| 5570 initialize_sequential_subtasks_for_young_gen_rescan(n_workers); | |
| 5571 | |
| 5572 // The dirty card rescan work is broken up into a "sequence" | |
| 5573 // of parallel tasks (per constituent space) that are dynamically | |
| 5574 // claimed by the parallel threads. | |
| 5575 cms_space->initialize_sequential_subtasks_for_rescan(n_workers); | |
| 5576 perm_space->initialize_sequential_subtasks_for_rescan(n_workers); | |
| 5577 | |
| 5578 // It turns out that even when we're using 1 thread, doing the work in a | |
| 5579 // separate thread causes wide variance in run times. We can't help this | |
| 5580 // in the multi-threaded case, but we special-case n=1 here to get | |
| 5581 // repeatable measurements of the 1-thread overhead of the parallel code. | |
| 5582 if (n_workers > 1) { | |
|
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5583 // Make refs discovery MT-safe, if it isn't already: it may not |
|
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5584 // necessarily be so, since it's possible that we are doing |
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5585 // ST marking. |
|
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5586 ReferenceProcessorMTDiscoveryMutator mt(ref_processor(), true); |
|
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5587 GenCollectedHeap::StrongRootsScope srs(gch); |
| 0 | 5588 workers->run_task(&tsk); |
| 5589 } else { | |
|
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5590 GenCollectedHeap::StrongRootsScope srs(gch); |
| 0 | 5591 tsk.work(0); |
| 5592 } | |
| 5593 gch->set_par_threads(0); // 0 ==> non-parallel. | |
| 5594 // restore, single-threaded for now, any preserved marks | |
| 5595 // as a result of work_q overflow | |
| 5596 restore_preserved_marks_if_any(); | |
| 5597 } | |
| 5598 | |
| 5599 // Non-parallel version of remark | |
| 5600 void CMSCollector::do_remark_non_parallel() { | |
| 5601 ResourceMark rm; | |
| 5602 HandleMark hm; | |
| 5603 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 5604 MarkRefsIntoAndScanClosure | |
| 5605 mrias_cl(_span, ref_processor(), &_markBitMap, &_modUnionTable, | |
| 5606 &_markStack, &_revisitStack, this, | |
| 5607 false /* should_yield */, false /* not precleaning */); | |
| 5608 MarkFromDirtyCardsClosure | |
| 5609 markFromDirtyCardsClosure(this, _span, | |
| 5610 NULL, // space is set further below | |
| 5611 &_markBitMap, &_markStack, &_revisitStack, | |
| 5612 &mrias_cl); | |
| 5613 { | |
| 5614 TraceTime t("grey object rescan", PrintGCDetails, false, gclog_or_tty); | |
|
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5615 // Iterate over the dirty cards, setting the corresponding bits in the |
|
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|
5616 // mod union table. |
| 0 | 5617 { |
| 5618 ModUnionClosure modUnionClosure(&_modUnionTable); | |
| 5619 _ct->ct_bs()->dirty_card_iterate( | |
| 5620 _cmsGen->used_region(), | |
| 5621 &modUnionClosure); | |
| 5622 _ct->ct_bs()->dirty_card_iterate( | |
| 5623 _permGen->used_region(), | |
| 5624 &modUnionClosure); | |
| 5625 } | |
| 5626 // Having transferred these marks into the modUnionTable, we just need | |
| 5627 // to rescan the marked objects on the dirty cards in the modUnionTable. | |
| 5628 // The initial marking may have been done during an asynchronous | |
| 5629 // collection so there may be dirty bits in the mod-union table. | |
| 5630 const int alignment = | |
| 5631 CardTableModRefBS::card_size * BitsPerWord; | |
| 5632 { | |
| 5633 // ... First handle dirty cards in CMS gen | |
| 5634 markFromDirtyCardsClosure.set_space(_cmsGen->cmsSpace()); | |
| 5635 MemRegion ur = _cmsGen->used_region(); | |
| 5636 HeapWord* lb = ur.start(); | |
| 5637 HeapWord* ub = (HeapWord*)round_to((intptr_t)ur.end(), alignment); | |
| 5638 MemRegion cms_span(lb, ub); | |
| 5639 _modUnionTable.dirty_range_iterate_clear(cms_span, | |
| 5640 &markFromDirtyCardsClosure); | |
| 5641 verify_work_stacks_empty(); | |
| 5642 if (PrintCMSStatistics != 0) { | |
| 5643 gclog_or_tty->print(" (re-scanned "SIZE_FORMAT" dirty cards in cms gen) ", | |
| 5644 markFromDirtyCardsClosure.num_dirty_cards()); | |
| 5645 } | |
| 5646 } | |
| 5647 { | |
| 5648 // .. and then repeat for dirty cards in perm gen | |
| 5649 markFromDirtyCardsClosure.set_space(_permGen->cmsSpace()); | |
| 5650 MemRegion ur = _permGen->used_region(); | |
| 5651 HeapWord* lb = ur.start(); | |
| 5652 HeapWord* ub = (HeapWord*)round_to((intptr_t)ur.end(), alignment); | |
| 5653 MemRegion perm_span(lb, ub); | |
| 5654 _modUnionTable.dirty_range_iterate_clear(perm_span, | |
| 5655 &markFromDirtyCardsClosure); | |
| 5656 verify_work_stacks_empty(); | |
| 5657 if (PrintCMSStatistics != 0) { | |
| 5658 gclog_or_tty->print(" (re-scanned "SIZE_FORMAT" dirty cards in perm gen) ", | |
| 5659 markFromDirtyCardsClosure.num_dirty_cards()); | |
| 5660 } | |
| 5661 } | |
| 5662 } | |
| 5663 if (VerifyDuringGC && | |
| 5664 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
| 5665 HandleMark hm; // Discard invalid handles created during verification | |
| 5666 Universe::verify(true); | |
| 5667 } | |
| 5668 { | |
| 5669 TraceTime t("root rescan", PrintGCDetails, false, gclog_or_tty); | |
| 5670 | |
| 5671 verify_work_stacks_empty(); | |
| 5672 | |
| 5673 gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel. | |
|
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diff
changeset
|
5674 GenCollectedHeap::StrongRootsScope srs(gch); |
| 0 | 5675 gch->gen_process_strong_roots(_cmsGen->level(), |
| 5676 true, // younger gens as roots | |
|
989
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|
5677 false, // use the local StrongRootsScope |
| 0 | 5678 true, // collecting perm gen |
| 5679 SharedHeap::ScanningOption(roots_scanning_options()), | |
|
989
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|
5680 &mrias_cl, |
|
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|
5681 true, // walk code active on stacks |
|
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|
5682 NULL); |
|
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|
5683 assert(should_unload_classes() |
|
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diff
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|
5684 || (roots_scanning_options() & SharedHeap::SO_CodeCache), |
|
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|
5685 "if we didn't scan the code cache, we have to be ready to drop nmethods with expired weak oops"); |
| 0 | 5686 } |
| 5687 verify_work_stacks_empty(); | |
| 5688 // Restore evacuated mark words, if any, used for overflow list links | |
| 5689 if (!CMSOverflowEarlyRestoration) { | |
| 5690 restore_preserved_marks_if_any(); | |
| 5691 } | |
| 5692 verify_overflow_empty(); | |
| 5693 } | |
| 5694 | |
| 5695 //////////////////////////////////////////////////////// | |
| 5696 // Parallel Reference Processing Task Proxy Class | |
| 5697 //////////////////////////////////////////////////////// | |
|
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|
5698 class CMSRefProcTaskProxy: public AbstractGangTaskWOopQueues { |
| 0 | 5699 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; |
| 5700 CMSCollector* _collector; | |
| 5701 CMSBitMap* _mark_bit_map; | |
|
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|
5702 const MemRegion _span; |
| 0 | 5703 ProcessTask& _task; |
| 5704 | |
| 5705 public: | |
| 5706 CMSRefProcTaskProxy(ProcessTask& task, | |
| 5707 CMSCollector* collector, | |
| 5708 const MemRegion& span, | |
| 5709 CMSBitMap* mark_bit_map, | |
|
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|
5710 AbstractWorkGang* workers, |
| 0 | 5711 OopTaskQueueSet* task_queues): |
|
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|
5712 // XXX Should superclass AGTWOQ also know about AWG since it knows |
|
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|
5713 // about the task_queues used by the AWG? Then it could initialize |
|
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|
5714 // the terminator() object. See 6984287. The set_for_termination() |
|
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|
5715 // below is a temporary band-aid for the regression in 6984287. |
|
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|
5716 AbstractGangTaskWOopQueues("Process referents by policy in parallel", |
|
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|
5717 task_queues), |
| 0 | 5718 _task(task), |
|
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|
5719 _collector(collector), _span(span), _mark_bit_map(mark_bit_map) |
|
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|
5720 { |
|
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diff
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|
5721 assert(_collector->_span.equals(_span) && !_span.is_empty(), |
|
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|
5722 "Inconsistency in _span"); |
|
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|
5723 set_for_termination(workers->active_workers()); |
|
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|
5724 } |
| 0 | 5725 |
|
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diff
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|
5726 OopTaskQueueSet* task_queues() { return queues(); } |
| 0 | 5727 |
| 5728 OopTaskQueue* work_queue(int i) { return task_queues()->queue(i); } | |
| 5729 | |
| 5730 void do_work_steal(int i, | |
| 5731 CMSParDrainMarkingStackClosure* drain, | |
| 5732 CMSParKeepAliveClosure* keep_alive, | |
| 5733 int* seed); | |
| 5734 | |
| 5735 virtual void work(int i); | |
| 5736 }; | |
| 5737 | |
| 5738 void CMSRefProcTaskProxy::work(int i) { | |
|
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|
5739 assert(_collector->_span.equals(_span), "Inconsistency in _span"); |
| 0 | 5740 CMSParKeepAliveClosure par_keep_alive(_collector, _span, |
| 935 | 5741 _mark_bit_map, |
| 5742 &_collector->_revisitStack, | |
| 5743 work_queue(i)); | |
| 0 | 5744 CMSParDrainMarkingStackClosure par_drain_stack(_collector, _span, |
| 935 | 5745 _mark_bit_map, |
| 5746 &_collector->_revisitStack, | |
| 5747 work_queue(i)); | |
|
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|
5748 CMSIsAliveClosure is_alive_closure(_span, _mark_bit_map); |
| 0 | 5749 _task.work(i, is_alive_closure, par_keep_alive, par_drain_stack); |
| 5750 if (_task.marks_oops_alive()) { | |
| 5751 do_work_steal(i, &par_drain_stack, &par_keep_alive, | |
| 5752 _collector->hash_seed(i)); | |
| 5753 } | |
| 5754 assert(work_queue(i)->size() == 0, "work_queue should be empty"); | |
| 5755 assert(_collector->_overflow_list == NULL, "non-empty _overflow_list"); | |
| 5756 } | |
| 5757 | |
| 5758 class CMSRefEnqueueTaskProxy: public AbstractGangTask { | |
| 5759 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; | |
| 5760 EnqueueTask& _task; | |
| 5761 | |
| 5762 public: | |
| 5763 CMSRefEnqueueTaskProxy(EnqueueTask& task) | |
| 5764 : AbstractGangTask("Enqueue reference objects in parallel"), | |
| 5765 _task(task) | |
| 5766 { } | |
| 5767 | |
| 5768 virtual void work(int i) | |
| 5769 { | |
| 5770 _task.work(i); | |
| 5771 } | |
| 5772 }; | |
| 5773 | |
| 5774 CMSParKeepAliveClosure::CMSParKeepAliveClosure(CMSCollector* collector, | |
| 935 | 5775 MemRegion span, CMSBitMap* bit_map, CMSMarkStack* revisit_stack, |
| 5776 OopTaskQueue* work_queue): | |
| 5777 Par_KlassRememberingOopClosure(collector, NULL, revisit_stack), | |
| 0 | 5778 _span(span), |
| 5779 _bit_map(bit_map), | |
| 5780 _work_queue(work_queue), | |
| 935 | 5781 _mark_and_push(collector, span, bit_map, revisit_stack, work_queue), |
| 0 | 5782 _low_water_mark(MIN2((uint)(work_queue->max_elems()/4), |
| 5783 (uint)(CMSWorkQueueDrainThreshold * ParallelGCThreads))) | |
| 5784 { } | |
| 5785 | |
| 5786 // . see if we can share work_queues with ParNew? XXX | |
| 5787 void CMSRefProcTaskProxy::do_work_steal(int i, | |
| 5788 CMSParDrainMarkingStackClosure* drain, | |
| 5789 CMSParKeepAliveClosure* keep_alive, | |
| 5790 int* seed) { | |
| 5791 OopTaskQueue* work_q = work_queue(i); | |
| 5792 NOT_PRODUCT(int num_steals = 0;) | |
| 5793 oop obj_to_scan; | |
| 5794 | |
| 5795 while (true) { | |
| 5796 // Completely finish any left over work from (an) earlier round(s) | |
| 5797 drain->trim_queue(0); | |
|
679
cea947c8a988
6819891: ParNew: Fix work queue overflow code to deal correctly with +UseCompressedOops
ysr
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628
diff
changeset
|
5798 size_t num_from_overflow_list = MIN2((size_t)(work_q->max_elems() - work_q->size())/4, |
|
cea947c8a988
6819891: ParNew: Fix work queue overflow code to deal correctly with +UseCompressedOops
ysr
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628
diff
changeset
|
5799 (size_t)ParGCDesiredObjsFromOverflowList); |
| 0 | 5800 // Now check if there's any work in the overflow list |
|
1833
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1777
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changeset
|
5801 // Passing ParallelGCThreads as the third parameter, no_of_gc_threads, |
|
8b10f48633dc
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jmasa
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1777
diff
changeset
|
5802 // only affects the number of attempts made to get work from the |
|
8b10f48633dc
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jmasa
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1777
diff
changeset
|
5803 // overflow list and does not affect the number of workers. Just |
|
8b10f48633dc
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jmasa
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1777
diff
changeset
|
5804 // pass ParallelGCThreads so this behavior is unchanged. |
| 0 | 5805 if (_collector->par_take_from_overflow_list(num_from_overflow_list, |
|
1833
8b10f48633dc
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jmasa
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1777
diff
changeset
|
5806 work_q, |
|
8b10f48633dc
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jmasa
parents:
1777
diff
changeset
|
5807 ParallelGCThreads)) { |
| 0 | 5808 // Found something in global overflow list; |
| 5809 // not yet ready to go stealing work from others. | |
| 5810 // We'd like to assert(work_q->size() != 0, ...) | |
| 5811 // because we just took work from the overflow list, | |
| 5812 // but of course we can't, since all of that might have | |
| 5813 // been already stolen from us. | |
| 5814 continue; | |
| 5815 } | |
| 5816 // Verify that we have no work before we resort to stealing | |
| 5817 assert(work_q->size() == 0, "Have work, shouldn't steal"); | |
| 5818 // Try to steal from other queues that have work | |
| 5819 if (task_queues()->steal(i, seed, /* reference */ obj_to_scan)) { | |
| 5820 NOT_PRODUCT(num_steals++;) | |
| 5821 assert(obj_to_scan->is_oop(), "Oops, not an oop!"); | |
| 5822 assert(_mark_bit_map->isMarked((HeapWord*)obj_to_scan), "Stole an unmarked oop?"); | |
| 5823 // Do scanning work | |
| 5824 obj_to_scan->oop_iterate(keep_alive); | |
| 5825 // Loop around, finish this work, and try to steal some more | |
| 5826 } else if (terminator()->offer_termination()) { | |
| 5827 break; // nirvana from the infinite cycle | |
| 5828 } | |
| 5829 } | |
| 5830 NOT_PRODUCT( | |
| 5831 if (PrintCMSStatistics != 0) { | |
| 5832 gclog_or_tty->print("\n\t(%d: stole %d oops)", i, num_steals); | |
| 5833 } | |
| 5834 ) | |
| 5835 } | |
| 5836 | |
| 5837 void CMSRefProcTaskExecutor::execute(ProcessTask& task) | |
| 5838 { | |
| 5839 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
|
1833
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jmasa
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1777
diff
changeset
|
5840 FlexibleWorkGang* workers = gch->workers(); |
| 0 | 5841 assert(workers != NULL, "Need parallel worker threads."); |
| 5842 CMSRefProcTaskProxy rp_task(task, &_collector, | |
| 5843 _collector.ref_processor()->span(), | |
| 5844 _collector.markBitMap(), | |
|
1833
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diff
changeset
|
5845 workers, _collector.task_queues()); |
| 0 | 5846 workers->run_task(&rp_task); |
| 5847 } | |
| 5848 | |
| 5849 void CMSRefProcTaskExecutor::execute(EnqueueTask& task) | |
| 5850 { | |
| 5851 | |
| 5852 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
|
1833
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1777
diff
changeset
|
5853 FlexibleWorkGang* workers = gch->workers(); |
| 0 | 5854 assert(workers != NULL, "Need parallel worker threads."); |
| 5855 CMSRefEnqueueTaskProxy enq_task(task); | |
| 5856 workers->run_task(&enq_task); | |
| 5857 } | |
| 5858 | |
| 5859 void CMSCollector::refProcessingWork(bool asynch, bool clear_all_soft_refs) { | |
| 5860 | |
| 5861 ResourceMark rm; | |
| 5862 HandleMark hm; | |
| 5863 | |
| 5864 ReferenceProcessor* rp = ref_processor(); | |
| 5865 assert(rp->span().equals(_span), "Spans should be equal"); | |
|
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diff
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|
5866 assert(!rp->enqueuing_is_done(), "Enqueuing should not be complete"); |
|
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452
diff
changeset
|
5867 // Process weak references. |
|
457
27a80744a83b
6778647: snap(), snap_policy() should be renamed setup(), setup_policy()
ysr
parents:
453
diff
changeset
|
5868 rp->setup_policy(clear_all_soft_refs); |
|
453
c96030fff130
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parents:
452
diff
changeset
|
5869 verify_work_stacks_empty(); |
|
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diff
changeset
|
5870 |
| 0 | 5871 CMSKeepAliveClosure cmsKeepAliveClosure(this, _span, &_markBitMap, |
| 935 | 5872 &_markStack, &_revisitStack, |
| 5873 false /* !preclean */); | |
| 0 | 5874 CMSDrainMarkingStackClosure cmsDrainMarkingStackClosure(this, |
| 5875 _span, &_markBitMap, &_markStack, | |
|
452
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
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360
diff
changeset
|
5876 &cmsKeepAliveClosure, false /* !preclean */); |
| 0 | 5877 { |
| 5878 TraceTime t("weak refs processing", PrintGCDetails, false, gclog_or_tty); | |
| 5879 if (rp->processing_is_mt()) { | |
|
1833
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diff
changeset
|
5880 // 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
|
5881 // may have been a different number of threads doing the discovery |
|
8b10f48633dc
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jmasa
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1777
diff
changeset
|
5882 // and a different number of discovered lists may have Ref objects. |
|
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jmasa
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diff
changeset
|
5883 // That is OK as long as the Reference lists are balanced (see |
|
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|
5884 // balance_all_queues() and balance_queues()). |
|
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|
5885 |
|
2369
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2365
diff
changeset
|
5886 rp->set_active_mt_degree(ParallelGCThreads); |
| 0 | 5887 CMSRefProcTaskExecutor task_executor(*this); |
|
453
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diff
changeset
|
5888 rp->process_discovered_references(&_is_alive_closure, |
| 0 | 5889 &cmsKeepAliveClosure, |
| 5890 &cmsDrainMarkingStackClosure, | |
| 5891 &task_executor); | |
| 5892 } else { | |
|
453
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452
diff
changeset
|
5893 rp->process_discovered_references(&_is_alive_closure, |
| 0 | 5894 &cmsKeepAliveClosure, |
| 5895 &cmsDrainMarkingStackClosure, | |
| 5896 NULL); | |
| 5897 } | |
| 5898 verify_work_stacks_empty(); | |
| 5899 } | |
| 5900 | |
|
94
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
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9
diff
changeset
|
5901 if (should_unload_classes()) { |
| 0 | 5902 { |
| 5903 TraceTime t("class unloading", PrintGCDetails, false, gclog_or_tty); | |
| 5904 | |
| 5905 // Follow SystemDictionary roots and unload classes | |
| 5906 bool purged_class = SystemDictionary::do_unloading(&_is_alive_closure); | |
| 5907 | |
| 5908 // Follow CodeCache roots and unload any methods marked for unloading | |
| 5909 CodeCache::do_unloading(&_is_alive_closure, | |
| 5910 &cmsKeepAliveClosure, | |
| 5911 purged_class); | |
| 5912 | |
| 5913 cmsDrainMarkingStackClosure.do_void(); | |
| 5914 verify_work_stacks_empty(); | |
| 5915 | |
| 5916 // Update subklass/sibling/implementor links in KlassKlass descendants | |
| 5917 assert(!_revisitStack.isEmpty(), "revisit stack should not be empty"); | |
| 5918 oop k; | |
| 5919 while ((k = _revisitStack.pop()) != NULL) { | |
| 5920 ((Klass*)(oopDesc*)k)->follow_weak_klass_links( | |
| 5921 &_is_alive_closure, | |
| 5922 &cmsKeepAliveClosure); | |
| 5923 } | |
| 5924 assert(!ClassUnloading || | |
| 5925 (_markStack.isEmpty() && overflow_list_is_empty()), | |
| 5926 "Should not have found new reachable objects"); | |
| 5927 assert(_revisitStack.isEmpty(), "revisit stack should have been drained"); | |
| 5928 cmsDrainMarkingStackClosure.do_void(); | |
| 5929 verify_work_stacks_empty(); | |
| 5930 } | |
| 5931 | |
| 5932 { | |
|
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5933 TraceTime t("scrub symbol table", PrintGCDetails, false, gclog_or_tty); |
|
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5934 // Clean up unreferenced symbols in symbol table. |
|
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5935 SymbolTable::unlink(); |
| 0 | 5936 } |
| 5937 } | |
| 5938 | |
|
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5939 if (should_unload_classes() || !JavaObjectsInPerm) { |
|
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5940 TraceTime t("scrub string table", PrintGCDetails, false, gclog_or_tty); |
|
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5941 // Now clean up stale oops in StringTable |
|
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|
5942 StringTable::unlink(&_is_alive_closure); |
|
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|
5943 } |
|
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|
5944 |
| 0 | 5945 verify_work_stacks_empty(); |
| 5946 // Restore any preserved marks as a result of mark stack or | |
| 5947 // work queue overflow | |
| 5948 restore_preserved_marks_if_any(); // done single-threaded for now | |
| 5949 | |
| 5950 rp->set_enqueuing_is_done(true); | |
| 5951 if (rp->processing_is_mt()) { | |
|
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|
5952 rp->balance_all_queues(); |
| 0 | 5953 CMSRefProcTaskExecutor task_executor(*this); |
| 5954 rp->enqueue_discovered_references(&task_executor); | |
| 5955 } else { | |
| 5956 rp->enqueue_discovered_references(NULL); | |
| 5957 } | |
| 5958 rp->verify_no_references_recorded(); | |
| 5959 assert(!rp->discovery_enabled(), "should have been disabled"); | |
| 5960 } | |
| 5961 | |
| 5962 #ifndef PRODUCT | |
| 5963 void CMSCollector::check_correct_thread_executing() { | |
| 5964 Thread* t = Thread::current(); | |
| 5965 // Only the VM thread or the CMS thread should be here. | |
| 5966 assert(t->is_ConcurrentGC_thread() || t->is_VM_thread(), | |
| 5967 "Unexpected thread type"); | |
| 5968 // If this is the vm thread, the foreground process | |
| 5969 // should not be waiting. Note that _foregroundGCIsActive is | |
| 5970 // true while the foreground collector is waiting. | |
| 5971 if (_foregroundGCShouldWait) { | |
| 5972 // We cannot be the VM thread | |
| 5973 assert(t->is_ConcurrentGC_thread(), | |
| 5974 "Should be CMS thread"); | |
| 5975 } else { | |
| 5976 // We can be the CMS thread only if we are in a stop-world | |
| 5977 // phase of CMS collection. | |
| 5978 if (t->is_ConcurrentGC_thread()) { | |
| 5979 assert(_collectorState == InitialMarking || | |
| 5980 _collectorState == FinalMarking, | |
| 5981 "Should be a stop-world phase"); | |
| 5982 // The CMS thread should be holding the CMS_token. | |
| 5983 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 5984 "Potential interference with concurrently " | |
| 5985 "executing VM thread"); | |
| 5986 } | |
| 5987 } | |
| 5988 } | |
| 5989 #endif | |
| 5990 | |
| 5991 void CMSCollector::sweep(bool asynch) { | |
| 5992 assert(_collectorState == Sweeping, "just checking"); | |
| 5993 check_correct_thread_executing(); | |
| 5994 verify_work_stacks_empty(); | |
| 5995 verify_overflow_empty(); | |
|
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|
5996 increment_sweep_count(); |
|
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5997 TraceCMSMemoryManagerStats tms(_collectorState,GenCollectedHeap::heap()->gc_cause()); |
|
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5998 |
|
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5999 _inter_sweep_timer.stop(); |
|
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|
6000 _inter_sweep_estimate.sample(_inter_sweep_timer.seconds()); |
| 0 | 6001 size_policy()->avg_cms_free_at_sweep()->sample(_cmsGen->free()); |
| 6002 | |
| 6003 // PermGen verification support: If perm gen sweeping is disabled in | |
| 6004 // this cycle, we preserve the perm gen object "deadness" information | |
| 6005 // in the perm_gen_verify_bit_map. In order to do that we traverse | |
| 6006 // all blocks in perm gen and mark all dead objects. | |
|
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|
6007 if (verifying() && !should_unload_classes()) { |
| 0 | 6008 assert(perm_gen_verify_bit_map()->sizeInBits() != 0, |
| 6009 "Should have already been allocated"); | |
| 6010 MarkDeadObjectsClosure mdo(this, _permGen->cmsSpace(), | |
| 6011 markBitMap(), perm_gen_verify_bit_map()); | |
|
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|
6012 if (asynch) { |
|
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|
6013 CMSTokenSyncWithLocks ts(true, _permGen->freelistLock(), |
|
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|
6014 bitMapLock()); |
|
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|
6015 _permGen->cmsSpace()->blk_iterate(&mdo); |
|
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|
6016 } else { |
|
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|
6017 // In the case of synchronous sweep, we already have |
|
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|
6018 // the requisite locks/tokens. |
|
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|
6019 _permGen->cmsSpace()->blk_iterate(&mdo); |
|
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|
6020 } |
| 0 | 6021 } |
| 6022 | |
|
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6023 assert(!_intra_sweep_timer.is_active(), "Should not be active"); |
|
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6024 _intra_sweep_timer.reset(); |
|
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|
6025 _intra_sweep_timer.start(); |
| 0 | 6026 if (asynch) { |
| 6027 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
| 6028 CMSPhaseAccounting pa(this, "sweep", !PrintGCDetails); | |
| 6029 // First sweep the old gen then the perm gen | |
| 6030 { | |
| 6031 CMSTokenSyncWithLocks ts(true, _cmsGen->freelistLock(), | |
| 6032 bitMapLock()); | |
| 6033 sweepWork(_cmsGen, asynch); | |
| 6034 } | |
| 6035 | |
| 6036 // Now repeat for perm gen | |
|
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|
6037 if (should_unload_classes()) { |
| 0 | 6038 CMSTokenSyncWithLocks ts(true, _permGen->freelistLock(), |
| 6039 bitMapLock()); | |
| 6040 sweepWork(_permGen, asynch); | |
| 6041 } | |
| 6042 | |
| 6043 // Update Universe::_heap_*_at_gc figures. | |
| 6044 // We need all the free list locks to make the abstract state | |
| 6045 // transition from Sweeping to Resetting. See detailed note | |
| 6046 // further below. | |
| 6047 { | |
| 6048 CMSTokenSyncWithLocks ts(true, _cmsGen->freelistLock(), | |
| 6049 _permGen->freelistLock()); | |
| 6050 // Update heap occupancy information which is used as | |
| 6051 // input to soft ref clearing policy at the next gc. | |
| 6052 Universe::update_heap_info_at_gc(); | |
| 6053 _collectorState = Resizing; | |
| 6054 } | |
| 6055 } else { | |
| 6056 // already have needed locks | |
| 6057 sweepWork(_cmsGen, asynch); | |
| 6058 | |
|
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|
6059 if (should_unload_classes()) { |
| 0 | 6060 sweepWork(_permGen, asynch); |
| 6061 } | |
| 6062 // Update heap occupancy information which is used as | |
| 6063 // input to soft ref clearing policy at the next gc. | |
| 6064 Universe::update_heap_info_at_gc(); | |
| 6065 _collectorState = Resizing; | |
| 6066 } | |
| 6067 verify_work_stacks_empty(); | |
| 6068 verify_overflow_empty(); | |
| 6069 | |
|
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|
6070 _intra_sweep_timer.stop(); |
|
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|
6071 _intra_sweep_estimate.sample(_intra_sweep_timer.seconds()); |
|
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6072 |
|
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|
6073 _inter_sweep_timer.reset(); |
|
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|
6074 _inter_sweep_timer.start(); |
| 0 | 6075 |
| 6076 update_time_of_last_gc(os::javaTimeMillis()); | |
| 6077 | |
| 6078 // NOTE on abstract state transitions: | |
| 6079 // Mutators allocate-live and/or mark the mod-union table dirty | |
| 6080 // based on the state of the collection. The former is done in | |
| 6081 // the interval [Marking, Sweeping] and the latter in the interval | |
| 6082 // [Marking, Sweeping). Thus the transitions into the Marking state | |
| 6083 // and out of the Sweeping state must be synchronously visible | |
| 6084 // globally to the mutators. | |
| 6085 // The transition into the Marking state happens with the world | |
| 6086 // stopped so the mutators will globally see it. Sweeping is | |
| 6087 // done asynchronously by the background collector so the transition | |
| 6088 // from the Sweeping state to the Resizing state must be done | |
| 6089 // under the freelistLock (as is the check for whether to | |
| 6090 // allocate-live and whether to dirty the mod-union table). | |
| 6091 assert(_collectorState == Resizing, "Change of collector state to" | |
| 6092 " Resizing must be done under the freelistLocks (plural)"); | |
| 6093 | |
|
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|
6094 // Now that sweeping has been completed, we clear |
|
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|
6095 // the incremental_collection_failed flag, |
| 0 | 6096 // thus inviting a younger gen collection to promote into |
| 6097 // this generation. If such a promotion may still fail, | |
| 6098 // the flag will be set again when a young collection is | |
| 6099 // attempted. | |
| 6100 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
|
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|
6101 gch->clear_incremental_collection_failed(); // Worth retrying as fresh space may have been freed up |
| 0 | 6102 gch->update_full_collections_completed(_collection_count_start); |
| 6103 } | |
| 6104 | |
| 6105 // FIX ME!!! Looks like this belongs in CFLSpace, with | |
| 6106 // CMSGen merely delegating to it. | |
| 6107 void ConcurrentMarkSweepGeneration::setNearLargestChunk() { | |
|
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|
6108 double nearLargestPercent = FLSLargestBlockCoalesceProximity; |
| 0 | 6109 HeapWord* minAddr = _cmsSpace->bottom(); |
| 6110 HeapWord* largestAddr = | |
| 6111 (HeapWord*) _cmsSpace->dictionary()->findLargestDict(); | |
|
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|
6112 if (largestAddr == NULL) { |
| 0 | 6113 // The dictionary appears to be empty. In this case |
| 6114 // try to coalesce at the end of the heap. | |
| 6115 largestAddr = _cmsSpace->end(); | |
| 6116 } | |
| 6117 size_t largestOffset = pointer_delta(largestAddr, minAddr); | |
| 6118 size_t nearLargestOffset = | |
| 6119 (size_t)((double)largestOffset * nearLargestPercent) - MinChunkSize; | |
|
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|
6120 if (PrintFLSStatistics != 0) { |
|
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|
6121 gclog_or_tty->print_cr( |
|
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|
6122 "CMS: Large Block: " PTR_FORMAT ";" |
|
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|
6123 " Proximity: " PTR_FORMAT " -> " PTR_FORMAT, |
|
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|
6124 largestAddr, |
|
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|
6125 _cmsSpace->nearLargestChunk(), minAddr + nearLargestOffset); |
|
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|
6126 } |
| 0 | 6127 _cmsSpace->set_nearLargestChunk(minAddr + nearLargestOffset); |
| 6128 } | |
| 6129 | |
| 6130 bool ConcurrentMarkSweepGeneration::isNearLargestChunk(HeapWord* addr) { | |
| 6131 return addr >= _cmsSpace->nearLargestChunk(); | |
| 6132 } | |
| 6133 | |
| 6134 FreeChunk* ConcurrentMarkSweepGeneration::find_chunk_at_end() { | |
| 6135 return _cmsSpace->find_chunk_at_end(); | |
| 6136 } | |
| 6137 | |
| 6138 void ConcurrentMarkSweepGeneration::update_gc_stats(int current_level, | |
| 6139 bool full) { | |
| 6140 // The next lower level has been collected. Gather any statistics | |
| 6141 // that are of interest at this point. | |
| 6142 if (!full && (current_level + 1) == level()) { | |
| 6143 // Gather statistics on the young generation collection. | |
| 6144 collector()->stats().record_gc0_end(used()); | |
| 6145 } | |
| 6146 } | |
| 6147 | |
| 6148 CMSAdaptiveSizePolicy* ConcurrentMarkSweepGeneration::size_policy() { | |
| 6149 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 6150 assert(gch->kind() == CollectedHeap::GenCollectedHeap, | |
| 6151 "Wrong type of heap"); | |
| 6152 CMSAdaptiveSizePolicy* sp = (CMSAdaptiveSizePolicy*) | |
| 6153 gch->gen_policy()->size_policy(); | |
| 6154 assert(sp->is_gc_cms_adaptive_size_policy(), | |
| 6155 "Wrong type of size policy"); | |
| 6156 return sp; | |
| 6157 } | |
| 6158 | |
| 6159 void ConcurrentMarkSweepGeneration::rotate_debug_collection_type() { | |
| 6160 if (PrintGCDetails && Verbose) { | |
| 6161 gclog_or_tty->print("Rotate from %d ", _debug_collection_type); | |
| 6162 } | |
| 6163 _debug_collection_type = (CollectionTypes) (_debug_collection_type + 1); | |
| 6164 _debug_collection_type = | |
| 6165 (CollectionTypes) (_debug_collection_type % Unknown_collection_type); | |
| 6166 if (PrintGCDetails && Verbose) { | |
| 6167 gclog_or_tty->print_cr("to %d ", _debug_collection_type); | |
| 6168 } | |
| 6169 } | |
| 6170 | |
| 6171 void CMSCollector::sweepWork(ConcurrentMarkSweepGeneration* gen, | |
| 6172 bool asynch) { | |
| 6173 // We iterate over the space(s) underlying this generation, | |
| 6174 // checking the mark bit map to see if the bits corresponding | |
| 6175 // to specific blocks are marked or not. Blocks that are | |
| 6176 // marked are live and are not swept up. All remaining blocks | |
| 6177 // are swept up, with coalescing on-the-fly as we sweep up | |
| 6178 // contiguous free and/or garbage blocks: | |
| 6179 // We need to ensure that the sweeper synchronizes with allocators | |
| 6180 // and stop-the-world collectors. In particular, the following | |
| 6181 // locks are used: | |
| 6182 // . CMS token: if this is held, a stop the world collection cannot occur | |
| 6183 // . freelistLock: if this is held no allocation can occur from this | |
| 6184 // generation by another thread | |
| 6185 // . bitMapLock: if this is held, no other thread can access or update | |
| 6186 // | |
| 6187 | |
| 6188 // Note that we need to hold the freelistLock if we use | |
| 6189 // block iterate below; else the iterator might go awry if | |
| 6190 // a mutator (or promotion) causes block contents to change | |
| 6191 // (for instance if the allocator divvies up a block). | |
| 6192 // If we hold the free list lock, for all practical purposes | |
| 6193 // young generation GC's can't occur (they'll usually need to | |
| 6194 // promote), so we might as well prevent all young generation | |
| 6195 // GC's while we do a sweeping step. For the same reason, we might | |
| 6196 // as well take the bit map lock for the entire duration | |
| 6197 | |
| 6198 // check that we hold the requisite locks | |
| 6199 assert(have_cms_token(), "Should hold cms token"); | |
| 6200 assert( (asynch && ConcurrentMarkSweepThread::cms_thread_has_cms_token()) | |
| 6201 || (!asynch && ConcurrentMarkSweepThread::vm_thread_has_cms_token()), | |
| 6202 "Should possess CMS token to sweep"); | |
| 6203 assert_lock_strong(gen->freelistLock()); | |
| 6204 assert_lock_strong(bitMapLock()); | |
| 6205 | |
|
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6206 assert(!_inter_sweep_timer.is_active(), "Was switched off in an outer context"); |
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6207 assert(_intra_sweep_timer.is_active(), "Was switched on in an outer context"); |
|
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6208 gen->cmsSpace()->beginSweepFLCensus((float)(_inter_sweep_timer.seconds()), |
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6209 _inter_sweep_estimate.padded_average(), |
|
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6210 _intra_sweep_estimate.padded_average()); |
| 0 | 6211 gen->setNearLargestChunk(); |
| 6212 | |
| 6213 { | |
| 6214 SweepClosure sweepClosure(this, gen, &_markBitMap, | |
| 6215 CMSYield && asynch); | |
| 6216 gen->cmsSpace()->blk_iterate_careful(&sweepClosure); | |
| 6217 // We need to free-up/coalesce garbage/blocks from a | |
| 6218 // co-terminal free run. This is done in the SweepClosure | |
| 6219 // destructor; so, do not remove this scope, else the | |
| 6220 // end-of-sweep-census below will be off by a little bit. | |
| 6221 } | |
| 6222 gen->cmsSpace()->sweep_completed(); | |
|
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6223 gen->cmsSpace()->endSweepFLCensus(sweep_count()); |
|
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6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
6224 if (should_unload_classes()) { // unloaded classes this cycle, |
|
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
6225 _concurrent_cycles_since_last_unload = 0; // ... reset count |
|
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
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9
diff
changeset
|
6226 } else { // did not unload classes, |
|
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
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9
diff
changeset
|
6227 _concurrent_cycles_since_last_unload++; // ... increment count |
|
0834225a7916
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9
diff
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|
6228 } |
| 0 | 6229 } |
| 6230 | |
| 6231 // Reset CMS data structures (for now just the marking bit map) | |
| 6232 // preparatory for the next cycle. | |
| 6233 void CMSCollector::reset(bool asynch) { | |
| 6234 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 6235 CMSAdaptiveSizePolicy* sp = size_policy(); | |
| 6236 AdaptiveSizePolicyOutput(sp, gch->total_collections()); | |
| 6237 if (asynch) { | |
| 6238 CMSTokenSyncWithLocks ts(true, bitMapLock()); | |
| 6239 | |
| 6240 // If the state is not "Resetting", the foreground thread | |
| 6241 // has done a collection and the resetting. | |
| 6242 if (_collectorState != Resetting) { | |
| 6243 assert(_collectorState == Idling, "The state should only change" | |
| 6244 " because the foreground collector has finished the collection"); | |
| 6245 return; | |
| 6246 } | |
| 6247 | |
| 6248 // Clear the mark bitmap (no grey objects to start with) | |
| 6249 // for the next cycle. | |
| 6250 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
| 6251 CMSPhaseAccounting cmspa(this, "reset", !PrintGCDetails); | |
| 6252 | |
| 6253 HeapWord* curAddr = _markBitMap.startWord(); | |
| 6254 while (curAddr < _markBitMap.endWord()) { | |
| 6255 size_t remaining = pointer_delta(_markBitMap.endWord(), curAddr); | |
| 6256 MemRegion chunk(curAddr, MIN2(CMSBitMapYieldQuantum, remaining)); | |
| 6257 _markBitMap.clear_large_range(chunk); | |
| 6258 if (ConcurrentMarkSweepThread::should_yield() && | |
| 6259 !foregroundGCIsActive() && | |
| 6260 CMSYield) { | |
| 6261 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 6262 "CMS thread should hold CMS token"); | |
| 6263 assert_lock_strong(bitMapLock()); | |
| 6264 bitMapLock()->unlock(); | |
| 6265 ConcurrentMarkSweepThread::desynchronize(true); | |
| 6266 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 6267 stopTimer(); | |
| 6268 if (PrintCMSStatistics != 0) { | |
| 6269 incrementYields(); | |
| 6270 } | |
| 6271 icms_wait(); | |
| 6272 | |
| 6273 // See the comment in coordinator_yield() | |
| 6274 for (unsigned i = 0; i < CMSYieldSleepCount && | |
|
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diff
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|
6275 ConcurrentMarkSweepThread::should_yield() && |
|
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
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94
diff
changeset
|
6276 !CMSCollector::foregroundGCIsActive(); ++i) { |
| 0 | 6277 os::sleep(Thread::current(), 1, false); |
| 6278 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 6279 } | |
| 6280 | |
| 6281 ConcurrentMarkSweepThread::synchronize(true); | |
| 6282 bitMapLock()->lock_without_safepoint_check(); | |
| 6283 startTimer(); | |
| 6284 } | |
| 6285 curAddr = chunk.end(); | |
| 6286 } | |
|
1387
0bfd3fb24150
6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
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1289
diff
changeset
|
6287 // A successful mostly concurrent collection has been done. |
|
0bfd3fb24150
6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
jmasa
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1289
diff
changeset
|
6288 // 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
|
6289 // 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
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|
6290 // and count. |
|
0bfd3fb24150
6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
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diff
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|
6291 sp->reset_gc_overhead_limit_count(); |
| 0 | 6292 _collectorState = Idling; |
| 6293 } else { | |
| 6294 // already have the lock | |
| 6295 assert(_collectorState == Resetting, "just checking"); | |
| 6296 assert_lock_strong(bitMapLock()); | |
| 6297 _markBitMap.clear_all(); | |
| 6298 _collectorState = Idling; | |
| 6299 } | |
| 6300 | |
| 6301 // Stop incremental mode after a cycle completes, so that any future cycles | |
| 6302 // are triggered by allocation. | |
| 6303 stop_icms(); | |
| 6304 | |
| 6305 NOT_PRODUCT( | |
| 6306 if (RotateCMSCollectionTypes) { | |
| 6307 _cmsGen->rotate_debug_collection_type(); | |
| 6308 } | |
| 6309 ) | |
| 6310 } | |
| 6311 | |
| 6312 void CMSCollector::do_CMS_operation(CMS_op_type op) { | |
| 6313 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps); | |
| 6314 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
| 6315 TraceTime t("GC", PrintGC, !PrintGCDetails, gclog_or_tty); | |
| 6316 TraceCollectorStats tcs(counters()); | |
| 6317 | |
| 6318 switch (op) { | |
| 6319 case CMS_op_checkpointRootsInitial: { | |
|
2125
7246a374a9f2
6458402: 3 jvmti tests fail with CMS and +ExplicitGCInvokesConcurrent
kamg
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1994
diff
changeset
|
6320 SvcGCMarker sgcm(SvcGCMarker::OTHER); |
| 0 | 6321 checkpointRootsInitial(true); // asynch |
| 6322 if (PrintGC) { | |
| 6323 _cmsGen->printOccupancy("initial-mark"); | |
| 6324 } | |
| 6325 break; | |
| 6326 } | |
| 6327 case CMS_op_checkpointRootsFinal: { | |
|
2125
7246a374a9f2
6458402: 3 jvmti tests fail with CMS and +ExplicitGCInvokesConcurrent
kamg
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1994
diff
changeset
|
6328 SvcGCMarker sgcm(SvcGCMarker::OTHER); |
| 0 | 6329 checkpointRootsFinal(true, // asynch |
| 6330 false, // !clear_all_soft_refs | |
| 6331 false); // !init_mark_was_synchronous | |
| 6332 if (PrintGC) { | |
| 6333 _cmsGen->printOccupancy("remark"); | |
| 6334 } | |
| 6335 break; | |
| 6336 } | |
| 6337 default: | |
| 6338 fatal("No such CMS_op"); | |
| 6339 } | |
| 6340 } | |
| 6341 | |
| 6342 #ifndef PRODUCT | |
| 6343 size_t const CMSCollector::skip_header_HeapWords() { | |
| 6344 return FreeChunk::header_size(); | |
| 6345 } | |
| 6346 | |
| 6347 // Try and collect here conditions that should hold when | |
| 6348 // CMS thread is exiting. The idea is that the foreground GC | |
| 6349 // thread should not be blocked if it wants to terminate | |
| 6350 // the CMS thread and yet continue to run the VM for a while | |
| 6351 // after that. | |
| 6352 void CMSCollector::verify_ok_to_terminate() const { | |
| 6353 assert(Thread::current()->is_ConcurrentGC_thread(), | |
| 6354 "should be called by CMS thread"); | |
| 6355 assert(!_foregroundGCShouldWait, "should be false"); | |
| 6356 // We could check here that all the various low-level locks | |
| 6357 // are not held by the CMS thread, but that is overkill; see | |
| 6358 // also CMSThread::verify_ok_to_terminate() where the CGC_lock | |
| 6359 // is checked. | |
| 6360 } | |
| 6361 #endif | |
| 6362 | |
| 6363 size_t CMSCollector::block_size_using_printezis_bits(HeapWord* addr) const { | |
|
453
c96030fff130
6684579: SoftReference processing can be made more efficient
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452
diff
changeset
|
6364 assert(_markBitMap.isMarked(addr) && _markBitMap.isMarked(addr + 1), |
|
c96030fff130
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452
diff
changeset
|
6365 "missing Printezis mark?"); |
| 0 | 6366 HeapWord* nextOneAddr = _markBitMap.getNextMarkedWordAddress(addr + 2); |
| 6367 size_t size = pointer_delta(nextOneAddr + 1, addr); | |
| 6368 assert(size == CompactibleFreeListSpace::adjustObjectSize(size), | |
| 6369 "alignment problem"); | |
| 6370 assert(size >= 3, "Necessary for Printezis marks to work"); | |
| 6371 return size; | |
| 6372 } | |
| 6373 | |
| 6374 // A variant of the above (block_size_using_printezis_bits()) except | |
| 6375 // that we return 0 if the P-bits are not yet set. | |
| 6376 size_t CMSCollector::block_size_if_printezis_bits(HeapWord* addr) const { | |
|
2226
c5a923563727
6912621: iCMS: Error: assert(_markBitMap.isMarked(addr + 1),"Missing Printezis bit?")
ysr
parents:
2177
diff
changeset
|
6377 if (_markBitMap.isMarked(addr + 1)) { |
|
c5a923563727
6912621: iCMS: Error: assert(_markBitMap.isMarked(addr + 1),"Missing Printezis bit?")
ysr
parents:
2177
diff
changeset
|
6378 assert(_markBitMap.isMarked(addr), "P-bit can be set only for marked objects"); |
| 0 | 6379 HeapWord* nextOneAddr = _markBitMap.getNextMarkedWordAddress(addr + 2); |
| 6380 size_t size = pointer_delta(nextOneAddr + 1, addr); | |
| 6381 assert(size == CompactibleFreeListSpace::adjustObjectSize(size), | |
| 6382 "alignment problem"); | |
| 6383 assert(size >= 3, "Necessary for Printezis marks to work"); | |
| 6384 return size; | |
|
2226
c5a923563727
6912621: iCMS: Error: assert(_markBitMap.isMarked(addr + 1),"Missing Printezis bit?")
ysr
parents:
2177
diff
changeset
|
6385 } |
|
c5a923563727
6912621: iCMS: Error: assert(_markBitMap.isMarked(addr + 1),"Missing Printezis bit?")
ysr
parents:
2177
diff
changeset
|
6386 return 0; |
| 0 | 6387 } |
| 6388 | |
| 6389 HeapWord* CMSCollector::next_card_start_after_block(HeapWord* addr) const { | |
| 6390 size_t sz = 0; | |
| 6391 oop p = (oop)addr; | |
| 187 | 6392 if (p->klass_or_null() != NULL && p->is_parsable()) { |
| 0 | 6393 sz = CompactibleFreeListSpace::adjustObjectSize(p->size()); |
| 6394 } else { | |
| 6395 sz = block_size_using_printezis_bits(addr); | |
| 6396 } | |
| 6397 assert(sz > 0, "size must be nonzero"); | |
| 6398 HeapWord* next_block = addr + sz; | |
| 6399 HeapWord* next_card = (HeapWord*)round_to((uintptr_t)next_block, | |
| 6400 CardTableModRefBS::card_size); | |
| 6401 assert(round_down((uintptr_t)addr, CardTableModRefBS::card_size) < | |
| 6402 round_down((uintptr_t)next_card, CardTableModRefBS::card_size), | |
| 6403 "must be different cards"); | |
| 6404 return next_card; | |
| 6405 } | |
| 6406 | |
| 6407 | |
| 6408 // CMS Bit Map Wrapper ///////////////////////////////////////// | |
| 6409 | |
| 6410 // Construct a CMS bit map infrastructure, but don't create the | |
| 6411 // bit vector itself. That is done by a separate call CMSBitMap::allocate() | |
| 6412 // further below. | |
| 6413 CMSBitMap::CMSBitMap(int shifter, int mutex_rank, const char* mutex_name): | |
|
342
37f87013dfd8
6711316: Open source the Garbage-First garbage collector
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143
diff
changeset
|
6414 _bm(), |
| 0 | 6415 _shifter(shifter), |
| 6416 _lock(mutex_rank >= 0 ? new Mutex(mutex_rank, mutex_name, true) : NULL) | |
| 6417 { | |
| 6418 _bmStartWord = 0; | |
| 6419 _bmWordSize = 0; | |
| 6420 } | |
| 6421 | |
| 6422 bool CMSBitMap::allocate(MemRegion mr) { | |
| 6423 _bmStartWord = mr.start(); | |
| 6424 _bmWordSize = mr.word_size(); | |
| 6425 ReservedSpace brs(ReservedSpace::allocation_align_size_up( | |
| 6426 (_bmWordSize >> (_shifter + LogBitsPerByte)) + 1)); | |
| 6427 if (!brs.is_reserved()) { | |
| 6428 warning("CMS bit map allocation failure"); | |
| 6429 return false; | |
| 6430 } | |
| 6431 // For now we'll just commit all of the bit map up fromt. | |
| 6432 // Later on we'll try to be more parsimonious with swap. | |
| 6433 if (!_virtual_space.initialize(brs, brs.size())) { | |
| 6434 warning("CMS bit map backing store failure"); | |
| 6435 return false; | |
| 6436 } | |
| 6437 assert(_virtual_space.committed_size() == brs.size(), | |
| 6438 "didn't reserve backing store for all of CMS bit map?"); | |
|
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143
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|
6439 _bm.set_map((BitMap::bm_word_t*)_virtual_space.low()); |
| 0 | 6440 assert(_virtual_space.committed_size() << (_shifter + LogBitsPerByte) >= |
| 6441 _bmWordSize, "inconsistency in bit map sizing"); | |
| 6442 _bm.set_size(_bmWordSize >> _shifter); | |
| 6443 | |
| 6444 // bm.clear(); // can we rely on getting zero'd memory? verify below | |
| 6445 assert(isAllClear(), | |
| 6446 "Expected zero'd memory from ReservedSpace constructor"); | |
| 6447 assert(_bm.size() == heapWordDiffToOffsetDiff(sizeInWords()), | |
| 6448 "consistency check"); | |
| 6449 return true; | |
| 6450 } | |
| 6451 | |
| 6452 void CMSBitMap::dirty_range_iterate_clear(MemRegion mr, MemRegionClosure* cl) { | |
| 6453 HeapWord *next_addr, *end_addr, *last_addr; | |
| 6454 assert_locked(); | |
| 6455 assert(covers(mr), "out-of-range error"); | |
| 6456 // XXX assert that start and end are appropriately aligned | |
| 6457 for (next_addr = mr.start(), end_addr = mr.end(); | |
| 6458 next_addr < end_addr; next_addr = last_addr) { | |
| 6459 MemRegion dirty_region = getAndClearMarkedRegion(next_addr, end_addr); | |
| 6460 last_addr = dirty_region.end(); | |
| 6461 if (!dirty_region.is_empty()) { | |
| 6462 cl->do_MemRegion(dirty_region); | |
| 6463 } else { | |
| 6464 assert(last_addr == end_addr, "program logic"); | |
| 6465 return; | |
| 6466 } | |
| 6467 } | |
| 6468 } | |
| 6469 | |
| 6470 #ifndef PRODUCT | |
| 6471 void CMSBitMap::assert_locked() const { | |
| 6472 CMSLockVerifier::assert_locked(lock()); | |
| 6473 } | |
| 6474 | |
| 6475 bool CMSBitMap::covers(MemRegion mr) const { | |
| 6476 // assert(_bm.map() == _virtual_space.low(), "map inconsistency"); | |
| 6477 assert((size_t)_bm.size() == (_bmWordSize >> _shifter), | |
| 6478 "size inconsistency"); | |
| 6479 return (mr.start() >= _bmStartWord) && | |
| 6480 (mr.end() <= endWord()); | |
| 6481 } | |
| 6482 | |
| 6483 bool CMSBitMap::covers(HeapWord* start, size_t size) const { | |
| 6484 return (start >= _bmStartWord && (start + size) <= endWord()); | |
| 6485 } | |
| 6486 | |
| 6487 void CMSBitMap::verifyNoOneBitsInRange(HeapWord* left, HeapWord* right) { | |
| 6488 // verify that there are no 1 bits in the interval [left, right) | |
| 6489 FalseBitMapClosure falseBitMapClosure; | |
| 6490 iterate(&falseBitMapClosure, left, right); | |
| 6491 } | |
| 6492 | |
| 6493 void CMSBitMap::region_invariant(MemRegion mr) | |
| 6494 { | |
| 6495 assert_locked(); | |
| 6496 // mr = mr.intersection(MemRegion(_bmStartWord, _bmWordSize)); | |
| 6497 assert(!mr.is_empty(), "unexpected empty region"); | |
| 6498 assert(covers(mr), "mr should be covered by bit map"); | |
| 6499 // convert address range into offset range | |
| 6500 size_t start_ofs = heapWordToOffset(mr.start()); | |
| 6501 // Make sure that end() is appropriately aligned | |
| 6502 assert(mr.end() == (HeapWord*)round_to((intptr_t)mr.end(), | |
| 6503 (1 << (_shifter+LogHeapWordSize))), | |
| 6504 "Misaligned mr.end()"); | |
| 6505 size_t end_ofs = heapWordToOffset(mr.end()); | |
| 6506 assert(end_ofs > start_ofs, "Should mark at least one bit"); | |
| 6507 } | |
| 6508 | |
| 6509 #endif | |
| 6510 | |
| 6511 bool CMSMarkStack::allocate(size_t size) { | |
| 6512 // allocate a stack of the requisite depth | |
| 6513 ReservedSpace rs(ReservedSpace::allocation_align_size_up( | |
| 6514 size * sizeof(oop))); | |
| 6515 if (!rs.is_reserved()) { | |
| 6516 warning("CMSMarkStack allocation failure"); | |
| 6517 return false; | |
| 6518 } | |
| 6519 if (!_virtual_space.initialize(rs, rs.size())) { | |
| 6520 warning("CMSMarkStack backing store failure"); | |
| 6521 return false; | |
| 6522 } | |
| 6523 assert(_virtual_space.committed_size() == rs.size(), | |
| 6524 "didn't reserve backing store for all of CMS stack?"); | |
| 6525 _base = (oop*)(_virtual_space.low()); | |
| 6526 _index = 0; | |
| 6527 _capacity = size; | |
| 6528 NOT_PRODUCT(_max_depth = 0); | |
| 6529 return true; | |
| 6530 } | |
| 6531 | |
| 6532 // XXX FIX ME !!! In the MT case we come in here holding a | |
| 6533 // leaf lock. For printing we need to take a further lock | |
| 6534 // which has lower rank. We need to recallibrate the two | |
| 6535 // lock-ranks involved in order to be able to rpint the | |
| 6536 // messages below. (Or defer the printing to the caller. | |
| 6537 // For now we take the expedient path of just disabling the | |
| 6538 // messages for the problematic case.) | |
| 6539 void CMSMarkStack::expand() { | |
| 1284 | 6540 assert(_capacity <= MarkStackSizeMax, "stack bigger than permitted"); |
| 6541 if (_capacity == MarkStackSizeMax) { | |
| 0 | 6542 if (_hit_limit++ == 0 && !CMSConcurrentMTEnabled && PrintGCDetails) { |
| 6543 // We print a warning message only once per CMS cycle. | |
| 6544 gclog_or_tty->print_cr(" (benign) Hit CMSMarkStack max size limit"); | |
| 6545 } | |
| 6546 return; | |
| 6547 } | |
| 6548 // Double capacity if possible | |
| 1284 | 6549 size_t new_capacity = MIN2(_capacity*2, MarkStackSizeMax); |
| 0 | 6550 // Do not give up existing stack until we have managed to |
| 6551 // get the double capacity that we desired. | |
| 6552 ReservedSpace rs(ReservedSpace::allocation_align_size_up( | |
| 6553 new_capacity * sizeof(oop))); | |
| 6554 if (rs.is_reserved()) { | |
| 6555 // Release the backing store associated with old stack | |
| 6556 _virtual_space.release(); | |
| 6557 // Reinitialize virtual space for new stack | |
| 6558 if (!_virtual_space.initialize(rs, rs.size())) { | |
| 6559 fatal("Not enough swap for expanded marking stack"); | |
| 6560 } | |
| 6561 _base = (oop*)(_virtual_space.low()); | |
| 6562 _index = 0; | |
| 6563 _capacity = new_capacity; | |
| 6564 } else if (_failed_double++ == 0 && !CMSConcurrentMTEnabled && PrintGCDetails) { | |
| 6565 // Failed to double capacity, continue; | |
| 6566 // we print a detail message only once per CMS cycle. | |
| 6567 gclog_or_tty->print(" (benign) Failed to expand marking stack from "SIZE_FORMAT"K to " | |
| 6568 SIZE_FORMAT"K", | |
| 6569 _capacity / K, new_capacity / K); | |
| 6570 } | |
| 6571 } | |
| 6572 | |
| 6573 | |
| 6574 // Closures | |
| 6575 // XXX: there seems to be a lot of code duplication here; | |
| 6576 // should refactor and consolidate common code. | |
| 6577 | |
| 6578 // This closure is used to mark refs into the CMS generation in | |
| 6579 // the CMS bit map. Called at the first checkpoint. This closure | |
| 6580 // assumes that we do not need to re-mark dirty cards; if the CMS | |
| 6581 // generation on which this is used is not an oldest (modulo perm gen) | |
| 6582 // generation then this will lose younger_gen cards! | |
| 6583 | |
| 6584 MarkRefsIntoClosure::MarkRefsIntoClosure( | |
|
994
753cf9794df9
6885169: merge of 4957990 and 6863023 causes conflict on do_nmethods
jrose
parents:
993
diff
changeset
|
6585 MemRegion span, CMSBitMap* bitMap): |
| 0 | 6586 _span(span), |
|
994
753cf9794df9
6885169: merge of 4957990 and 6863023 causes conflict on do_nmethods
jrose
parents:
993
diff
changeset
|
6587 _bitMap(bitMap) |
| 0 | 6588 { |
| 6589 assert(_ref_processor == NULL, "deliberately left NULL"); | |
| 6590 assert(_bitMap->covers(_span), "_bitMap/_span mismatch"); | |
| 6591 } | |
| 6592 | |
|
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6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
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94
diff
changeset
|
6593 void MarkRefsIntoClosure::do_oop(oop obj) { |
| 0 | 6594 // if p points into _span, then mark corresponding bit in _markBitMap |
|
113
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6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
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94
diff
changeset
|
6595 assert(obj->is_oop(), "expected an oop"); |
|
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6596 HeapWord* addr = (HeapWord*)obj; |
|
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6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6597 if (_span.contains(addr)) { |
|
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6598 // 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
|
6599 _bitMap->mark(addr); |
|
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6600 } |
|
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6601 } |
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6602 |
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6603 void MarkRefsIntoClosure::do_oop(oop* p) { MarkRefsIntoClosure::do_oop_work(p); } |
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6604 void MarkRefsIntoClosure::do_oop(narrowOop* p) { MarkRefsIntoClosure::do_oop_work(p); } |
| 0 | 6605 |
| 6606 // A variant of the above, used for CMS marking verification. | |
| 6607 MarkRefsIntoVerifyClosure::MarkRefsIntoVerifyClosure( | |
|
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6608 MemRegion span, CMSBitMap* verification_bm, CMSBitMap* cms_bm): |
| 0 | 6609 _span(span), |
| 6610 _verification_bm(verification_bm), | |
|
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6611 _cms_bm(cms_bm) |
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6612 { |
| 0 | 6613 assert(_ref_processor == NULL, "deliberately left NULL"); |
| 6614 assert(_verification_bm->covers(_span), "_verification_bm/_span mismatch"); | |
| 6615 } | |
| 6616 | |
|
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6617 void MarkRefsIntoVerifyClosure::do_oop(oop obj) { |
| 0 | 6618 // if p points into _span, then mark corresponding bit in _markBitMap |
|
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6619 assert(obj->is_oop(), "expected an oop"); |
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6620 HeapWord* addr = (HeapWord*)obj; |
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6621 if (_span.contains(addr)) { |
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6622 _verification_bm->mark(addr); |
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6623 if (!_cms_bm->isMarked(addr)) { |
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6624 oop(addr)->print(); |
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6625 gclog_or_tty->print_cr(" (" INTPTR_FORMAT " should have been marked)", addr); |
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6626 fatal("... aborting"); |
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6627 } |
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6628 } |
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6629 } |
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6630 |
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6631 void MarkRefsIntoVerifyClosure::do_oop(oop* p) { MarkRefsIntoVerifyClosure::do_oop_work(p); } |
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6632 void MarkRefsIntoVerifyClosure::do_oop(narrowOop* p) { MarkRefsIntoVerifyClosure::do_oop_work(p); } |
| 0 | 6633 |
| 6634 ////////////////////////////////////////////////// | |
| 6635 // MarkRefsIntoAndScanClosure | |
| 6636 ////////////////////////////////////////////////// | |
| 6637 | |
| 6638 MarkRefsIntoAndScanClosure::MarkRefsIntoAndScanClosure(MemRegion span, | |
| 6639 ReferenceProcessor* rp, | |
| 6640 CMSBitMap* bit_map, | |
| 6641 CMSBitMap* mod_union_table, | |
| 6642 CMSMarkStack* mark_stack, | |
| 6643 CMSMarkStack* revisit_stack, | |
| 6644 CMSCollector* collector, | |
| 6645 bool should_yield, | |
| 6646 bool concurrent_precleaning): | |
| 6647 _collector(collector), | |
| 6648 _span(span), | |
| 6649 _bit_map(bit_map), | |
| 6650 _mark_stack(mark_stack), | |
| 6651 _pushAndMarkClosure(collector, span, rp, bit_map, mod_union_table, | |
| 6652 mark_stack, revisit_stack, concurrent_precleaning), | |
| 6653 _yield(should_yield), | |
| 6654 _concurrent_precleaning(concurrent_precleaning), | |
| 6655 _freelistLock(NULL) | |
| 6656 { | |
| 6657 _ref_processor = rp; | |
| 6658 assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL"); | |
| 6659 } | |
| 6660 | |
| 6661 // This closure is used to mark refs into the CMS generation at the | |
| 6662 // second (final) checkpoint, and to scan and transitively follow | |
| 6663 // the unmarked oops. It is also used during the concurrent precleaning | |
| 6664 // phase while scanning objects on dirty cards in the CMS generation. | |
| 6665 // The marks are made in the marking bit map and the marking stack is | |
| 6666 // used for keeping the (newly) grey objects during the scan. | |
| 6667 // The parallel version (Par_...) appears further below. | |
|
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6668 void MarkRefsIntoAndScanClosure::do_oop(oop obj) { |
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6669 if (obj != NULL) { |
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6670 assert(obj->is_oop(), "expected an oop"); |
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6671 HeapWord* addr = (HeapWord*)obj; |
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6672 assert(_mark_stack->isEmpty(), "pre-condition (eager drainage)"); |
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6673 assert(_collector->overflow_list_is_empty(), |
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6674 "overflow list should be empty"); |
| 0 | 6675 if (_span.contains(addr) && |
| 6676 !_bit_map->isMarked(addr)) { | |
| 6677 // mark bit map (object is now grey) | |
| 6678 _bit_map->mark(addr); | |
| 6679 // push on marking stack (stack should be empty), and drain the | |
| 6680 // stack by applying this closure to the oops in the oops popped | |
| 6681 // from the stack (i.e. blacken the grey objects) | |
|
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6682 bool res = _mark_stack->push(obj); |
| 0 | 6683 assert(res, "Should have space to push on empty stack"); |
| 6684 do { | |
| 6685 oop new_oop = _mark_stack->pop(); | |
| 6686 assert(new_oop != NULL && new_oop->is_oop(), "Expected an oop"); | |
| 6687 assert(new_oop->is_parsable(), "Found unparsable oop"); | |
| 6688 assert(_bit_map->isMarked((HeapWord*)new_oop), | |
| 6689 "only grey objects on this stack"); | |
| 6690 // iterate over the oops in this oop, marking and pushing | |
| 6691 // the ones in CMS heap (i.e. in _span). | |
| 6692 new_oop->oop_iterate(&_pushAndMarkClosure); | |
| 6693 // check if it's time to yield | |
| 6694 do_yield_check(); | |
| 6695 } while (!_mark_stack->isEmpty() || | |
| 6696 (!_concurrent_precleaning && take_from_overflow_list())); | |
| 6697 // if marking stack is empty, and we are not doing this | |
| 6698 // during precleaning, then check the overflow list | |
| 6699 } | |
| 6700 assert(_mark_stack->isEmpty(), "post-condition (eager drainage)"); | |
| 6701 assert(_collector->overflow_list_is_empty(), | |
| 6702 "overflow list was drained above"); | |
| 6703 // We could restore evacuated mark words, if any, used for | |
| 6704 // overflow list links here because the overflow list is | |
| 6705 // provably empty here. That would reduce the maximum | |
| 6706 // size requirements for preserved_{oop,mark}_stack. | |
| 6707 // But we'll just postpone it until we are all done | |
| 6708 // so we can just stream through. | |
| 6709 if (!_concurrent_precleaning && CMSOverflowEarlyRestoration) { | |
| 6710 _collector->restore_preserved_marks_if_any(); | |
| 6711 assert(_collector->no_preserved_marks(), "No preserved marks"); | |
| 6712 } | |
| 6713 assert(!CMSOverflowEarlyRestoration || _collector->no_preserved_marks(), | |
| 6714 "All preserved marks should have been restored above"); | |
| 6715 } | |
| 6716 } | |
| 6717 | |
|
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6718 void MarkRefsIntoAndScanClosure::do_oop(oop* p) { MarkRefsIntoAndScanClosure::do_oop_work(p); } |
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6719 void MarkRefsIntoAndScanClosure::do_oop(narrowOop* p) { MarkRefsIntoAndScanClosure::do_oop_work(p); } |
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6720 |
| 0 | 6721 void MarkRefsIntoAndScanClosure::do_yield_work() { |
| 6722 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 6723 "CMS thread should hold CMS token"); | |
| 6724 assert_lock_strong(_freelistLock); | |
| 6725 assert_lock_strong(_bit_map->lock()); | |
| 6726 // relinquish the free_list_lock and bitMaplock() | |
| 935 | 6727 DEBUG_ONLY(RememberKlassesChecker mux(false);) |
| 0 | 6728 _bit_map->lock()->unlock(); |
| 6729 _freelistLock->unlock(); | |
| 6730 ConcurrentMarkSweepThread::desynchronize(true); | |
| 6731 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 6732 _collector->stopTimer(); | |
| 6733 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 6734 if (PrintCMSStatistics != 0) { | |
| 6735 _collector->incrementYields(); | |
| 6736 } | |
| 6737 _collector->icms_wait(); | |
| 6738 | |
| 6739 // See the comment in coordinator_yield() | |
|
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6740 for (unsigned i = 0; |
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6741 i < CMSYieldSleepCount && |
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6742 ConcurrentMarkSweepThread::should_yield() && |
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6743 !CMSCollector::foregroundGCIsActive(); |
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6744 ++i) { |
| 0 | 6745 os::sleep(Thread::current(), 1, false); |
| 6746 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 6747 } | |
| 6748 | |
| 6749 ConcurrentMarkSweepThread::synchronize(true); | |
| 6750 _freelistLock->lock_without_safepoint_check(); | |
| 6751 _bit_map->lock()->lock_without_safepoint_check(); | |
| 6752 _collector->startTimer(); | |
| 6753 } | |
| 6754 | |
| 6755 /////////////////////////////////////////////////////////// | |
| 6756 // Par_MarkRefsIntoAndScanClosure: a parallel version of | |
| 6757 // MarkRefsIntoAndScanClosure | |
| 6758 /////////////////////////////////////////////////////////// | |
| 6759 Par_MarkRefsIntoAndScanClosure::Par_MarkRefsIntoAndScanClosure( | |
| 6760 CMSCollector* collector, MemRegion span, ReferenceProcessor* rp, | |
| 6761 CMSBitMap* bit_map, OopTaskQueue* work_queue, CMSMarkStack* revisit_stack): | |
| 6762 _span(span), | |
| 6763 _bit_map(bit_map), | |
| 6764 _work_queue(work_queue), | |
| 6765 _low_water_mark(MIN2((uint)(work_queue->max_elems()/4), | |
| 6766 (uint)(CMSWorkQueueDrainThreshold * ParallelGCThreads))), | |
| 6767 _par_pushAndMarkClosure(collector, span, rp, bit_map, work_queue, | |
| 6768 revisit_stack) | |
| 6769 { | |
| 6770 _ref_processor = rp; | |
| 6771 assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL"); | |
| 6772 } | |
| 6773 | |
| 6774 // This closure is used to mark refs into the CMS generation at the | |
| 6775 // second (final) checkpoint, and to scan and transitively follow | |
| 6776 // the unmarked oops. The marks are made in the marking bit map and | |
| 6777 // the work_queue is used for keeping the (newly) grey objects during | |
| 6778 // the scan phase whence they are also available for stealing by parallel | |
| 6779 // threads. Since the marking bit map is shared, updates are | |
| 6780 // synchronized (via CAS). | |
|
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6781 void Par_MarkRefsIntoAndScanClosure::do_oop(oop obj) { |
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6782 if (obj != NULL) { |
| 0 | 6783 // Ignore mark word because this could be an already marked oop |
| 6784 // that may be chained at the end of the overflow list. | |
|
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6785 assert(obj->is_oop(true), "expected an oop"); |
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6786 HeapWord* addr = (HeapWord*)obj; |
| 0 | 6787 if (_span.contains(addr) && |
| 6788 !_bit_map->isMarked(addr)) { | |
| 6789 // mark bit map (object will become grey): | |
| 6790 // It is possible for several threads to be | |
| 6791 // trying to "claim" this object concurrently; | |
| 6792 // the unique thread that succeeds in marking the | |
| 6793 // object first will do the subsequent push on | |
| 6794 // to the work queue (or overflow list). | |
| 6795 if (_bit_map->par_mark(addr)) { | |
| 6796 // push on work_queue (which may not be empty), and trim the | |
| 6797 // queue to an appropriate length by applying this closure to | |
| 6798 // the oops in the oops popped from the stack (i.e. blacken the | |
| 6799 // grey objects) | |
|
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6800 bool res = _work_queue->push(obj); |
| 0 | 6801 assert(res, "Low water mark should be less than capacity?"); |
| 6802 trim_queue(_low_water_mark); | |
| 6803 } // Else, another thread claimed the object | |
| 6804 } | |
| 6805 } | |
| 6806 } | |
| 6807 | |
|
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6808 void Par_MarkRefsIntoAndScanClosure::do_oop(oop* p) { Par_MarkRefsIntoAndScanClosure::do_oop_work(p); } |
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6809 void Par_MarkRefsIntoAndScanClosure::do_oop(narrowOop* p) { Par_MarkRefsIntoAndScanClosure::do_oop_work(p); } |
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6810 |
| 0 | 6811 // This closure is used to rescan the marked objects on the dirty cards |
| 6812 // in the mod union table and the card table proper. | |
| 6813 size_t ScanMarkedObjectsAgainCarefullyClosure::do_object_careful_m( | |
| 6814 oop p, MemRegion mr) { | |
| 6815 | |
| 6816 size_t size = 0; | |
| 6817 HeapWord* addr = (HeapWord*)p; | |
| 6818 DEBUG_ONLY(_collector->verify_work_stacks_empty();) | |
| 6819 assert(_span.contains(addr), "we are scanning the CMS generation"); | |
| 6820 // check if it's time to yield | |
| 6821 if (do_yield_check()) { | |
| 6822 // We yielded for some foreground stop-world work, | |
| 6823 // and we have been asked to abort this ongoing preclean cycle. | |
| 6824 return 0; | |
| 6825 } | |
| 6826 if (_bitMap->isMarked(addr)) { | |
| 6827 // it's marked; is it potentially uninitialized? | |
| 187 | 6828 if (p->klass_or_null() != NULL) { |
|
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6829 // If is_conc_safe is false, the object may be undergoing |
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6830 // change by the VM outside a safepoint. Don't try to |
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6831 // scan it, but rather leave it for the remark phase. |
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6832 if (CMSPermGenPrecleaningEnabled && |
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6833 (!p->is_conc_safe() || !p->is_parsable())) { |
| 0 | 6834 // Signal precleaning to redirty the card since |
| 6835 // the klass pointer is already installed. | |
| 6836 assert(size == 0, "Initial value"); | |
| 6837 } else { | |
| 6838 assert(p->is_parsable(), "must be parsable."); | |
| 6839 // an initialized object; ignore mark word in verification below | |
| 6840 // since we are running concurrent with mutators | |
| 6841 assert(p->is_oop(true), "should be an oop"); | |
| 6842 if (p->is_objArray()) { | |
| 6843 // objArrays are precisely marked; restrict scanning | |
| 6844 // to dirty cards only. | |
| 187 | 6845 size = CompactibleFreeListSpace::adjustObjectSize( |
| 6846 p->oop_iterate(_scanningClosure, mr)); | |
| 0 | 6847 } else { |
| 6848 // A non-array may have been imprecisely marked; we need | |
| 6849 // to scan object in its entirety. | |
| 6850 size = CompactibleFreeListSpace::adjustObjectSize( | |
| 6851 p->oop_iterate(_scanningClosure)); | |
| 6852 } | |
| 6853 #ifdef DEBUG | |
| 6854 size_t direct_size = | |
| 6855 CompactibleFreeListSpace::adjustObjectSize(p->size()); | |
| 6856 assert(size == direct_size, "Inconsistency in size"); | |
| 6857 assert(size >= 3, "Necessary for Printezis marks to work"); | |
| 6858 if (!_bitMap->isMarked(addr+1)) { | |
| 6859 _bitMap->verifyNoOneBitsInRange(addr+2, addr+size); | |
| 6860 } else { | |
| 6861 _bitMap->verifyNoOneBitsInRange(addr+2, addr+size-1); | |
| 6862 assert(_bitMap->isMarked(addr+size-1), | |
| 6863 "inconsistent Printezis mark"); | |
| 6864 } | |
| 6865 #endif // DEBUG | |
| 6866 } | |
| 6867 } else { | |
| 6868 // an unitialized object | |
| 6869 assert(_bitMap->isMarked(addr+1), "missing Printezis mark?"); | |
| 6870 HeapWord* nextOneAddr = _bitMap->getNextMarkedWordAddress(addr + 2); | |
| 6871 size = pointer_delta(nextOneAddr + 1, addr); | |
| 6872 assert(size == CompactibleFreeListSpace::adjustObjectSize(size), | |
| 6873 "alignment problem"); | |
| 6874 // Note that pre-cleaning needn't redirty the card. OopDesc::set_klass() | |
| 6875 // will dirty the card when the klass pointer is installed in the | |
| 6876 // object (signalling the completion of initialization). | |
| 6877 } | |
| 6878 } else { | |
| 6879 // Either a not yet marked object or an uninitialized object | |
| 187 | 6880 if (p->klass_or_null() == NULL || !p->is_parsable()) { |
| 0 | 6881 // An uninitialized object, skip to the next card, since |
| 6882 // we may not be able to read its P-bits yet. | |
| 6883 assert(size == 0, "Initial value"); | |
| 6884 } else { | |
| 6885 // An object not (yet) reached by marking: we merely need to | |
| 6886 // compute its size so as to go look at the next block. | |
| 6887 assert(p->is_oop(true), "should be an oop"); | |
| 6888 size = CompactibleFreeListSpace::adjustObjectSize(p->size()); | |
| 6889 } | |
| 6890 } | |
| 6891 DEBUG_ONLY(_collector->verify_work_stacks_empty();) | |
| 6892 return size; | |
| 6893 } | |
| 6894 | |
| 6895 void ScanMarkedObjectsAgainCarefullyClosure::do_yield_work() { | |
| 6896 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 6897 "CMS thread should hold CMS token"); | |
| 6898 assert_lock_strong(_freelistLock); | |
| 6899 assert_lock_strong(_bitMap->lock()); | |
| 935 | 6900 DEBUG_ONLY(RememberKlassesChecker mux(false);) |
| 0 | 6901 // relinquish the free_list_lock and bitMaplock() |
| 6902 _bitMap->lock()->unlock(); | |
| 6903 _freelistLock->unlock(); | |
| 6904 ConcurrentMarkSweepThread::desynchronize(true); | |
| 6905 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 6906 _collector->stopTimer(); | |
| 6907 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 6908 if (PrintCMSStatistics != 0) { | |
| 6909 _collector->incrementYields(); | |
| 6910 } | |
| 6911 _collector->icms_wait(); | |
| 6912 | |
| 6913 // See the comment in coordinator_yield() | |
| 6914 for (unsigned i = 0; i < CMSYieldSleepCount && | |
|
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6915 ConcurrentMarkSweepThread::should_yield() && |
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6916 !CMSCollector::foregroundGCIsActive(); ++i) { |
| 0 | 6917 os::sleep(Thread::current(), 1, false); |
| 6918 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 6919 } | |
| 6920 | |
| 6921 ConcurrentMarkSweepThread::synchronize(true); | |
| 6922 _freelistLock->lock_without_safepoint_check(); | |
| 6923 _bitMap->lock()->lock_without_safepoint_check(); | |
| 6924 _collector->startTimer(); | |
| 6925 } | |
| 6926 | |
| 6927 | |
| 6928 ////////////////////////////////////////////////////////////////// | |
| 6929 // SurvivorSpacePrecleanClosure | |
| 6930 ////////////////////////////////////////////////////////////////// | |
| 6931 // This (single-threaded) closure is used to preclean the oops in | |
| 6932 // the survivor spaces. | |
| 6933 size_t SurvivorSpacePrecleanClosure::do_object_careful(oop p) { | |
| 6934 | |
| 6935 HeapWord* addr = (HeapWord*)p; | |
| 6936 DEBUG_ONLY(_collector->verify_work_stacks_empty();) | |
| 6937 assert(!_span.contains(addr), "we are scanning the survivor spaces"); | |
| 187 | 6938 assert(p->klass_or_null() != NULL, "object should be initializd"); |
| 0 | 6939 assert(p->is_parsable(), "must be parsable."); |
| 6940 // an initialized object; ignore mark word in verification below | |
| 6941 // since we are running concurrent with mutators | |
| 6942 assert(p->is_oop(true), "should be an oop"); | |
| 6943 // Note that we do not yield while we iterate over | |
| 6944 // the interior oops of p, pushing the relevant ones | |
| 6945 // on our marking stack. | |
| 6946 size_t size = p->oop_iterate(_scanning_closure); | |
| 6947 do_yield_check(); | |
| 6948 // Observe that below, we do not abandon the preclean | |
| 6949 // phase as soon as we should; rather we empty the | |
| 6950 // marking stack before returning. This is to satisfy | |
| 6951 // some existing assertions. In general, it may be a | |
| 6952 // good idea to abort immediately and complete the marking | |
| 6953 // from the grey objects at a later time. | |
| 6954 while (!_mark_stack->isEmpty()) { | |
| 6955 oop new_oop = _mark_stack->pop(); | |
| 6956 assert(new_oop != NULL && new_oop->is_oop(), "Expected an oop"); | |
| 6957 assert(new_oop->is_parsable(), "Found unparsable oop"); | |
| 6958 assert(_bit_map->isMarked((HeapWord*)new_oop), | |
| 6959 "only grey objects on this stack"); | |
| 6960 // iterate over the oops in this oop, marking and pushing | |
| 6961 // the ones in CMS heap (i.e. in _span). | |
| 6962 new_oop->oop_iterate(_scanning_closure); | |
| 6963 // check if it's time to yield | |
| 6964 do_yield_check(); | |
| 6965 } | |
| 6966 unsigned int after_count = | |
| 6967 GenCollectedHeap::heap()->total_collections(); | |
| 6968 bool abort = (_before_count != after_count) || | |
| 6969 _collector->should_abort_preclean(); | |
| 6970 return abort ? 0 : size; | |
| 6971 } | |
| 6972 | |
| 6973 void SurvivorSpacePrecleanClosure::do_yield_work() { | |
| 6974 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 6975 "CMS thread should hold CMS token"); | |
| 6976 assert_lock_strong(_bit_map->lock()); | |
| 935 | 6977 DEBUG_ONLY(RememberKlassesChecker smx(false);) |
| 0 | 6978 // Relinquish the bit map lock |
| 6979 _bit_map->lock()->unlock(); | |
| 6980 ConcurrentMarkSweepThread::desynchronize(true); | |
| 6981 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 6982 _collector->stopTimer(); | |
| 6983 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 6984 if (PrintCMSStatistics != 0) { | |
| 6985 _collector->incrementYields(); | |
| 6986 } | |
| 6987 _collector->icms_wait(); | |
| 6988 | |
| 6989 // See the comment in coordinator_yield() | |
| 6990 for (unsigned i = 0; i < CMSYieldSleepCount && | |
| 6991 ConcurrentMarkSweepThread::should_yield() && | |
| 6992 !CMSCollector::foregroundGCIsActive(); ++i) { | |
| 6993 os::sleep(Thread::current(), 1, false); | |
| 6994 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 6995 } | |
| 6996 | |
| 6997 ConcurrentMarkSweepThread::synchronize(true); | |
| 6998 _bit_map->lock()->lock_without_safepoint_check(); | |
| 6999 _collector->startTimer(); | |
| 7000 } | |
| 7001 | |
| 7002 // This closure is used to rescan the marked objects on the dirty cards | |
| 7003 // in the mod union table and the card table proper. In the parallel | |
| 7004 // case, although the bitMap is shared, we do a single read so the | |
| 7005 // isMarked() query is "safe". | |
| 7006 bool ScanMarkedObjectsAgainClosure::do_object_bm(oop p, MemRegion mr) { | |
| 7007 // Ignore mark word because we are running concurrent with mutators | |
| 7008 assert(p->is_oop_or_null(true), "expected an oop or null"); | |
| 7009 HeapWord* addr = (HeapWord*)p; | |
| 7010 assert(_span.contains(addr), "we are scanning the CMS generation"); | |
| 7011 bool is_obj_array = false; | |
| 7012 #ifdef DEBUG | |
| 7013 if (!_parallel) { | |
| 7014 assert(_mark_stack->isEmpty(), "pre-condition (eager drainage)"); | |
| 7015 assert(_collector->overflow_list_is_empty(), | |
| 7016 "overflow list should be empty"); | |
| 7017 | |
| 7018 } | |
| 7019 #endif // DEBUG | |
| 7020 if (_bit_map->isMarked(addr)) { | |
| 7021 // Obj arrays are precisely marked, non-arrays are not; | |
| 7022 // so we scan objArrays precisely and non-arrays in their | |
| 7023 // entirety. | |
| 7024 if (p->is_objArray()) { | |
| 7025 is_obj_array = true; | |
| 7026 if (_parallel) { | |
| 7027 p->oop_iterate(_par_scan_closure, mr); | |
| 7028 } else { | |
| 7029 p->oop_iterate(_scan_closure, mr); | |
| 7030 } | |
| 7031 } else { | |
| 7032 if (_parallel) { | |
| 7033 p->oop_iterate(_par_scan_closure); | |
| 7034 } else { | |
| 7035 p->oop_iterate(_scan_closure); | |
| 7036 } | |
| 7037 } | |
| 7038 } | |
| 7039 #ifdef DEBUG | |
| 7040 if (!_parallel) { | |
| 7041 assert(_mark_stack->isEmpty(), "post-condition (eager drainage)"); | |
| 7042 assert(_collector->overflow_list_is_empty(), | |
| 7043 "overflow list should be empty"); | |
| 7044 | |
| 7045 } | |
| 7046 #endif // DEBUG | |
| 7047 return is_obj_array; | |
| 7048 } | |
| 7049 | |
| 7050 MarkFromRootsClosure::MarkFromRootsClosure(CMSCollector* collector, | |
| 7051 MemRegion span, | |
| 7052 CMSBitMap* bitMap, CMSMarkStack* markStack, | |
| 7053 CMSMarkStack* revisitStack, | |
| 7054 bool should_yield, bool verifying): | |
| 7055 _collector(collector), | |
| 7056 _span(span), | |
| 7057 _bitMap(bitMap), | |
| 7058 _mut(&collector->_modUnionTable), | |
| 7059 _markStack(markStack), | |
| 7060 _revisitStack(revisitStack), | |
| 7061 _yield(should_yield), | |
| 7062 _skipBits(0) | |
| 7063 { | |
| 7064 assert(_markStack->isEmpty(), "stack should be empty"); | |
| 7065 _finger = _bitMap->startWord(); | |
| 7066 _threshold = _finger; | |
| 7067 assert(_collector->_restart_addr == NULL, "Sanity check"); | |
| 7068 assert(_span.contains(_finger), "Out of bounds _finger?"); | |
| 7069 DEBUG_ONLY(_verifying = verifying;) | |
| 7070 } | |
| 7071 | |
| 7072 void MarkFromRootsClosure::reset(HeapWord* addr) { | |
| 7073 assert(_markStack->isEmpty(), "would cause duplicates on stack"); | |
| 7074 assert(_span.contains(addr), "Out of bounds _finger?"); | |
| 7075 _finger = addr; | |
| 7076 _threshold = (HeapWord*)round_to( | |
| 7077 (intptr_t)_finger, CardTableModRefBS::card_size); | |
| 7078 } | |
| 7079 | |
| 7080 // Should revisit to see if this should be restructured for | |
| 7081 // greater efficiency. | |
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7082 bool MarkFromRootsClosure::do_bit(size_t offset) { |
| 0 | 7083 if (_skipBits > 0) { |
| 7084 _skipBits--; | |
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7085 return true; |
| 0 | 7086 } |
| 7087 // convert offset into a HeapWord* | |
| 7088 HeapWord* addr = _bitMap->startWord() + offset; | |
| 7089 assert(_bitMap->endWord() && addr < _bitMap->endWord(), | |
| 7090 "address out of range"); | |
| 7091 assert(_bitMap->isMarked(addr), "tautology"); | |
| 7092 if (_bitMap->isMarked(addr+1)) { | |
| 7093 // this is an allocated but not yet initialized object | |
| 7094 assert(_skipBits == 0, "tautology"); | |
| 7095 _skipBits = 2; // skip next two marked bits ("Printezis-marks") | |
| 7096 oop p = oop(addr); | |
| 187 | 7097 if (p->klass_or_null() == NULL || !p->is_parsable()) { |
| 0 | 7098 DEBUG_ONLY(if (!_verifying) {) |
| 7099 // We re-dirty the cards on which this object lies and increase | |
| 7100 // the _threshold so that we'll come back to scan this object | |
| 7101 // during the preclean or remark phase. (CMSCleanOnEnter) | |
| 7102 if (CMSCleanOnEnter) { | |
| 7103 size_t sz = _collector->block_size_using_printezis_bits(addr); | |
| 7104 HeapWord* end_card_addr = (HeapWord*)round_to( | |
| 7105 (intptr_t)(addr+sz), CardTableModRefBS::card_size); | |
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7106 MemRegion redirty_range = MemRegion(addr, end_card_addr); |
| 0 | 7107 assert(!redirty_range.is_empty(), "Arithmetical tautology"); |
| 7108 // Bump _threshold to end_card_addr; note that | |
| 7109 // _threshold cannot possibly exceed end_card_addr, anyhow. | |
| 7110 // This prevents future clearing of the card as the scan proceeds | |
| 7111 // to the right. | |
| 7112 assert(_threshold <= end_card_addr, | |
| 7113 "Because we are just scanning into this object"); | |
| 7114 if (_threshold < end_card_addr) { | |
| 7115 _threshold = end_card_addr; | |
| 7116 } | |
| 187 | 7117 if (p->klass_or_null() != NULL) { |
| 0 | 7118 // Redirty the range of cards... |
| 7119 _mut->mark_range(redirty_range); | |
| 7120 } // ...else the setting of klass will dirty the card anyway. | |
| 7121 } | |
| 7122 DEBUG_ONLY(}) | |
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7123 return true; |
| 0 | 7124 } |
| 7125 } | |
| 7126 scanOopsInOop(addr); | |
|
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7127 return true; |
| 0 | 7128 } |
| 7129 | |
| 7130 // We take a break if we've been at this for a while, | |
| 7131 // so as to avoid monopolizing the locks involved. | |
| 7132 void MarkFromRootsClosure::do_yield_work() { | |
| 7133 // First give up the locks, then yield, then re-lock | |
| 7134 // We should probably use a constructor/destructor idiom to | |
| 7135 // do this unlock/lock or modify the MutexUnlocker class to | |
| 7136 // serve our purpose. XXX | |
| 7137 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 7138 "CMS thread should hold CMS token"); | |
| 7139 assert_lock_strong(_bitMap->lock()); | |
| 935 | 7140 DEBUG_ONLY(RememberKlassesChecker mux(false);) |
| 0 | 7141 _bitMap->lock()->unlock(); |
| 7142 ConcurrentMarkSweepThread::desynchronize(true); | |
| 7143 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7144 _collector->stopTimer(); | |
| 7145 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 7146 if (PrintCMSStatistics != 0) { | |
| 7147 _collector->incrementYields(); | |
| 7148 } | |
| 7149 _collector->icms_wait(); | |
| 7150 | |
| 7151 // See the comment in coordinator_yield() | |
| 7152 for (unsigned i = 0; i < CMSYieldSleepCount && | |
| 7153 ConcurrentMarkSweepThread::should_yield() && | |
| 7154 !CMSCollector::foregroundGCIsActive(); ++i) { | |
| 7155 os::sleep(Thread::current(), 1, false); | |
| 7156 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7157 } | |
| 7158 | |
| 7159 ConcurrentMarkSweepThread::synchronize(true); | |
| 7160 _bitMap->lock()->lock_without_safepoint_check(); | |
| 7161 _collector->startTimer(); | |
| 7162 } | |
| 7163 | |
| 7164 void MarkFromRootsClosure::scanOopsInOop(HeapWord* ptr) { | |
| 7165 assert(_bitMap->isMarked(ptr), "expected bit to be set"); | |
| 7166 assert(_markStack->isEmpty(), | |
| 7167 "should drain stack to limit stack usage"); | |
| 7168 // convert ptr to an oop preparatory to scanning | |
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7169 oop obj = oop(ptr); |
| 0 | 7170 // Ignore mark word in verification below, since we |
| 7171 // may be running concurrent with mutators. | |
|
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7172 assert(obj->is_oop(true), "should be an oop"); |
| 0 | 7173 assert(_finger <= ptr, "_finger runneth ahead"); |
| 7174 // advance the finger to right end of this object | |
|
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7175 _finger = ptr + obj->size(); |
| 0 | 7176 assert(_finger > ptr, "we just incremented it above"); |
| 7177 // On large heaps, it may take us some time to get through | |
| 7178 // the marking phase (especially if running iCMS). During | |
| 7179 // this time it's possible that a lot of mutations have | |
| 7180 // accumulated in the card table and the mod union table -- | |
| 7181 // these mutation records are redundant until we have | |
| 7182 // actually traced into the corresponding card. | |
| 7183 // Here, we check whether advancing the finger would make | |
| 7184 // us cross into a new card, and if so clear corresponding | |
| 7185 // cards in the MUT (preclean them in the card-table in the | |
| 7186 // future). | |
| 7187 | |
| 7188 DEBUG_ONLY(if (!_verifying) {) | |
| 7189 // The clean-on-enter optimization is disabled by default, | |
| 7190 // until we fix 6178663. | |
| 7191 if (CMSCleanOnEnter && (_finger > _threshold)) { | |
| 7192 // [_threshold, _finger) represents the interval | |
| 7193 // of cards to be cleared in MUT (or precleaned in card table). | |
| 7194 // The set of cards to be cleared is all those that overlap | |
| 7195 // with the interval [_threshold, _finger); note that | |
| 7196 // _threshold is always kept card-aligned but _finger isn't | |
| 7197 // always card-aligned. | |
| 7198 HeapWord* old_threshold = _threshold; | |
| 7199 assert(old_threshold == (HeapWord*)round_to( | |
| 7200 (intptr_t)old_threshold, CardTableModRefBS::card_size), | |
| 7201 "_threshold should always be card-aligned"); | |
| 7202 _threshold = (HeapWord*)round_to( | |
| 7203 (intptr_t)_finger, CardTableModRefBS::card_size); | |
| 7204 MemRegion mr(old_threshold, _threshold); | |
| 7205 assert(!mr.is_empty(), "Control point invariant"); | |
| 7206 assert(_span.contains(mr), "Should clear within span"); | |
| 7207 // XXX When _finger crosses from old gen into perm gen | |
| 7208 // we may be doing unnecessary cleaning; do better in the | |
| 7209 // future by detecting that condition and clearing fewer | |
| 7210 // MUT/CT entries. | |
| 7211 _mut->clear_range(mr); | |
| 7212 } | |
| 7213 DEBUG_ONLY(}) | |
| 7214 // Note: the finger doesn't advance while we drain | |
| 7215 // the stack below. | |
| 7216 PushOrMarkClosure pushOrMarkClosure(_collector, | |
| 7217 _span, _bitMap, _markStack, | |
| 7218 _revisitStack, | |
| 7219 _finger, this); | |
|
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7220 bool res = _markStack->push(obj); |
| 0 | 7221 assert(res, "Empty non-zero size stack should have space for single push"); |
| 7222 while (!_markStack->isEmpty()) { | |
| 7223 oop new_oop = _markStack->pop(); | |
| 7224 // Skip verifying header mark word below because we are | |
| 7225 // running concurrent with mutators. | |
| 7226 assert(new_oop->is_oop(true), "Oops! expected to pop an oop"); | |
| 7227 // now scan this oop's oops | |
| 7228 new_oop->oop_iterate(&pushOrMarkClosure); | |
| 7229 do_yield_check(); | |
| 7230 } | |
| 7231 assert(_markStack->isEmpty(), "tautology, emphasizing post-condition"); | |
| 7232 } | |
| 7233 | |
| 7234 Par_MarkFromRootsClosure::Par_MarkFromRootsClosure(CMSConcMarkingTask* task, | |
| 7235 CMSCollector* collector, MemRegion span, | |
| 7236 CMSBitMap* bit_map, | |
| 7237 OopTaskQueue* work_queue, | |
| 7238 CMSMarkStack* overflow_stack, | |
| 7239 CMSMarkStack* revisit_stack, | |
| 7240 bool should_yield): | |
| 7241 _collector(collector), | |
| 7242 _whole_span(collector->_span), | |
| 7243 _span(span), | |
| 7244 _bit_map(bit_map), | |
| 7245 _mut(&collector->_modUnionTable), | |
| 7246 _work_queue(work_queue), | |
| 7247 _overflow_stack(overflow_stack), | |
| 7248 _revisit_stack(revisit_stack), | |
| 7249 _yield(should_yield), | |
| 7250 _skip_bits(0), | |
| 7251 _task(task) | |
| 7252 { | |
| 7253 assert(_work_queue->size() == 0, "work_queue should be empty"); | |
| 7254 _finger = span.start(); | |
| 7255 _threshold = _finger; // XXX Defer clear-on-enter optimization for now | |
| 7256 assert(_span.contains(_finger), "Out of bounds _finger?"); | |
| 7257 } | |
| 7258 | |
| 7259 // Should revisit to see if this should be restructured for | |
| 7260 // greater efficiency. | |
|
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7261 bool Par_MarkFromRootsClosure::do_bit(size_t offset) { |
| 0 | 7262 if (_skip_bits > 0) { |
| 7263 _skip_bits--; | |
|
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7264 return true; |
| 0 | 7265 } |
| 7266 // convert offset into a HeapWord* | |
| 7267 HeapWord* addr = _bit_map->startWord() + offset; | |
| 7268 assert(_bit_map->endWord() && addr < _bit_map->endWord(), | |
| 7269 "address out of range"); | |
| 7270 assert(_bit_map->isMarked(addr), "tautology"); | |
| 7271 if (_bit_map->isMarked(addr+1)) { | |
| 7272 // this is an allocated object that might not yet be initialized | |
| 7273 assert(_skip_bits == 0, "tautology"); | |
| 7274 _skip_bits = 2; // skip next two marked bits ("Printezis-marks") | |
| 7275 oop p = oop(addr); | |
| 187 | 7276 if (p->klass_or_null() == NULL || !p->is_parsable()) { |
| 0 | 7277 // in the case of Clean-on-Enter optimization, redirty card |
| 7278 // and avoid clearing card by increasing the threshold. | |
|
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7279 return true; |
| 0 | 7280 } |
| 7281 } | |
| 7282 scan_oops_in_oop(addr); | |
|
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7283 return true; |
| 0 | 7284 } |
| 7285 | |
| 7286 void Par_MarkFromRootsClosure::scan_oops_in_oop(HeapWord* ptr) { | |
| 7287 assert(_bit_map->isMarked(ptr), "expected bit to be set"); | |
| 7288 // Should we assert that our work queue is empty or | |
| 7289 // below some drain limit? | |
| 7290 assert(_work_queue->size() == 0, | |
| 7291 "should drain stack to limit stack usage"); | |
| 7292 // convert ptr to an oop preparatory to scanning | |
|
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7293 oop obj = oop(ptr); |
| 0 | 7294 // Ignore mark word in verification below, since we |
| 7295 // may be running concurrent with mutators. | |
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7296 assert(obj->is_oop(true), "should be an oop"); |
| 0 | 7297 assert(_finger <= ptr, "_finger runneth ahead"); |
| 7298 // advance the finger to right end of this object | |
|
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7299 _finger = ptr + obj->size(); |
| 0 | 7300 assert(_finger > ptr, "we just incremented it above"); |
| 7301 // On large heaps, it may take us some time to get through | |
| 7302 // the marking phase (especially if running iCMS). During | |
| 7303 // this time it's possible that a lot of mutations have | |
| 7304 // accumulated in the card table and the mod union table -- | |
| 7305 // these mutation records are redundant until we have | |
| 7306 // actually traced into the corresponding card. | |
| 7307 // Here, we check whether advancing the finger would make | |
| 7308 // us cross into a new card, and if so clear corresponding | |
| 7309 // cards in the MUT (preclean them in the card-table in the | |
| 7310 // future). | |
| 7311 | |
| 7312 // The clean-on-enter optimization is disabled by default, | |
| 7313 // until we fix 6178663. | |
| 7314 if (CMSCleanOnEnter && (_finger > _threshold)) { | |
| 7315 // [_threshold, _finger) represents the interval | |
| 7316 // of cards to be cleared in MUT (or precleaned in card table). | |
| 7317 // The set of cards to be cleared is all those that overlap | |
| 7318 // with the interval [_threshold, _finger); note that | |
| 7319 // _threshold is always kept card-aligned but _finger isn't | |
| 7320 // always card-aligned. | |
| 7321 HeapWord* old_threshold = _threshold; | |
| 7322 assert(old_threshold == (HeapWord*)round_to( | |
| 7323 (intptr_t)old_threshold, CardTableModRefBS::card_size), | |
| 7324 "_threshold should always be card-aligned"); | |
| 7325 _threshold = (HeapWord*)round_to( | |
| 7326 (intptr_t)_finger, CardTableModRefBS::card_size); | |
| 7327 MemRegion mr(old_threshold, _threshold); | |
| 7328 assert(!mr.is_empty(), "Control point invariant"); | |
| 7329 assert(_span.contains(mr), "Should clear within span"); // _whole_span ?? | |
| 7330 // XXX When _finger crosses from old gen into perm gen | |
| 7331 // we may be doing unnecessary cleaning; do better in the | |
| 7332 // future by detecting that condition and clearing fewer | |
| 7333 // MUT/CT entries. | |
| 7334 _mut->clear_range(mr); | |
| 7335 } | |
| 7336 | |
| 7337 // Note: the local finger doesn't advance while we drain | |
| 7338 // the stack below, but the global finger sure can and will. | |
| 7339 HeapWord** gfa = _task->global_finger_addr(); | |
| 7340 Par_PushOrMarkClosure pushOrMarkClosure(_collector, | |
| 7341 _span, _bit_map, | |
| 7342 _work_queue, | |
| 7343 _overflow_stack, | |
| 7344 _revisit_stack, | |
| 7345 _finger, | |
| 7346 gfa, this); | |
|
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7347 bool res = _work_queue->push(obj); // overflow could occur here |
| 0 | 7348 assert(res, "Will hold once we use workqueues"); |
| 7349 while (true) { | |
| 7350 oop new_oop; | |
| 7351 if (!_work_queue->pop_local(new_oop)) { | |
| 7352 // We emptied our work_queue; check if there's stuff that can | |
| 7353 // be gotten from the overflow stack. | |
| 7354 if (CMSConcMarkingTask::get_work_from_overflow_stack( | |
| 7355 _overflow_stack, _work_queue)) { | |
| 7356 do_yield_check(); | |
| 7357 continue; | |
| 7358 } else { // done | |
| 7359 break; | |
| 7360 } | |
| 7361 } | |
| 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(_work_queue->size() == 0, "tautology, emphasizing post-condition"); | |
| 7370 } | |
| 7371 | |
| 7372 // Yield in response to a request from VM Thread or | |
| 7373 // from mutators. | |
| 7374 void Par_MarkFromRootsClosure::do_yield_work() { | |
| 7375 assert(_task != NULL, "sanity"); | |
| 7376 _task->yield(); | |
| 7377 } | |
| 7378 | |
| 7379 // A variant of the above used for verifying CMS marking work. | |
| 7380 MarkFromRootsVerifyClosure::MarkFromRootsVerifyClosure(CMSCollector* collector, | |
| 7381 MemRegion span, | |
| 7382 CMSBitMap* verification_bm, CMSBitMap* cms_bm, | |
| 7383 CMSMarkStack* mark_stack): | |
| 7384 _collector(collector), | |
| 7385 _span(span), | |
| 7386 _verification_bm(verification_bm), | |
| 7387 _cms_bm(cms_bm), | |
| 7388 _mark_stack(mark_stack), | |
| 7389 _pam_verify_closure(collector, span, verification_bm, cms_bm, | |
| 7390 mark_stack) | |
| 7391 { | |
| 7392 assert(_mark_stack->isEmpty(), "stack should be empty"); | |
| 7393 _finger = _verification_bm->startWord(); | |
| 7394 assert(_collector->_restart_addr == NULL, "Sanity check"); | |
| 7395 assert(_span.contains(_finger), "Out of bounds _finger?"); | |
| 7396 } | |
| 7397 | |
| 7398 void MarkFromRootsVerifyClosure::reset(HeapWord* addr) { | |
| 7399 assert(_mark_stack->isEmpty(), "would cause duplicates on stack"); | |
| 7400 assert(_span.contains(addr), "Out of bounds _finger?"); | |
| 7401 _finger = addr; | |
| 7402 } | |
| 7403 | |
| 7404 // Should revisit to see if this should be restructured for | |
| 7405 // greater efficiency. | |
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7406 bool MarkFromRootsVerifyClosure::do_bit(size_t offset) { |
| 0 | 7407 // convert offset into a HeapWord* |
| 7408 HeapWord* addr = _verification_bm->startWord() + offset; | |
| 7409 assert(_verification_bm->endWord() && addr < _verification_bm->endWord(), | |
| 7410 "address out of range"); | |
| 7411 assert(_verification_bm->isMarked(addr), "tautology"); | |
| 7412 assert(_cms_bm->isMarked(addr), "tautology"); | |
| 7413 | |
| 7414 assert(_mark_stack->isEmpty(), | |
| 7415 "should drain stack to limit stack usage"); | |
| 7416 // convert addr to an oop preparatory to scanning | |
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7417 oop obj = oop(addr); |
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7418 assert(obj->is_oop(), "should be an oop"); |
| 0 | 7419 assert(_finger <= addr, "_finger runneth ahead"); |
| 7420 // advance the finger to right end of this object | |
|
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7421 _finger = addr + obj->size(); |
| 0 | 7422 assert(_finger > addr, "we just incremented it above"); |
| 7423 // Note: the finger doesn't advance while we drain | |
| 7424 // the stack below. | |
|
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7425 bool res = _mark_stack->push(obj); |
| 0 | 7426 assert(res, "Empty non-zero size stack should have space for single push"); |
| 7427 while (!_mark_stack->isEmpty()) { | |
| 7428 oop new_oop = _mark_stack->pop(); | |
| 7429 assert(new_oop->is_oop(), "Oops! expected to pop an oop"); | |
| 7430 // now scan this oop's oops | |
| 7431 new_oop->oop_iterate(&_pam_verify_closure); | |
| 7432 } | |
| 7433 assert(_mark_stack->isEmpty(), "tautology, emphasizing post-condition"); | |
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7434 return true; |
| 0 | 7435 } |
| 7436 | |
| 7437 PushAndMarkVerifyClosure::PushAndMarkVerifyClosure( | |
| 7438 CMSCollector* collector, MemRegion span, | |
| 7439 CMSBitMap* verification_bm, CMSBitMap* cms_bm, | |
| 7440 CMSMarkStack* mark_stack): | |
| 7441 OopClosure(collector->ref_processor()), | |
| 7442 _collector(collector), | |
| 7443 _span(span), | |
| 7444 _verification_bm(verification_bm), | |
| 7445 _cms_bm(cms_bm), | |
| 7446 _mark_stack(mark_stack) | |
| 7447 { } | |
| 7448 | |
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7449 void PushAndMarkVerifyClosure::do_oop(oop* p) { PushAndMarkVerifyClosure::do_oop_work(p); } |
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7450 void PushAndMarkVerifyClosure::do_oop(narrowOop* p) { PushAndMarkVerifyClosure::do_oop_work(p); } |
| 0 | 7451 |
| 7452 // Upon stack overflow, we discard (part of) the stack, | |
| 7453 // remembering the least address amongst those discarded | |
| 7454 // in CMSCollector's _restart_address. | |
| 7455 void PushAndMarkVerifyClosure::handle_stack_overflow(HeapWord* lost) { | |
| 7456 // Remember the least grey address discarded | |
| 7457 HeapWord* ra = (HeapWord*)_mark_stack->least_value(lost); | |
| 7458 _collector->lower_restart_addr(ra); | |
| 7459 _mark_stack->reset(); // discard stack contents | |
| 7460 _mark_stack->expand(); // expand the stack if possible | |
| 7461 } | |
| 7462 | |
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7463 void PushAndMarkVerifyClosure::do_oop(oop obj) { |
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7464 assert(obj->is_oop_or_null(), "expected an oop or NULL"); |
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7465 HeapWord* addr = (HeapWord*)obj; |
| 0 | 7466 if (_span.contains(addr) && !_verification_bm->isMarked(addr)) { |
| 7467 // Oop lies in _span and isn't yet grey or black | |
| 7468 _verification_bm->mark(addr); // now grey | |
| 7469 if (!_cms_bm->isMarked(addr)) { | |
| 7470 oop(addr)->print(); | |
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7471 gclog_or_tty->print_cr(" (" INTPTR_FORMAT " should have been marked)", |
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7472 addr); |
| 0 | 7473 fatal("... aborting"); |
| 7474 } | |
| 7475 | |
|
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7476 if (!_mark_stack->push(obj)) { // stack overflow |
| 0 | 7477 if (PrintCMSStatistics != 0) { |
| 7478 gclog_or_tty->print_cr("CMS marking stack overflow (benign) at " | |
| 7479 SIZE_FORMAT, _mark_stack->capacity()); | |
| 7480 } | |
| 7481 assert(_mark_stack->isFull(), "Else push should have succeeded"); | |
| 7482 handle_stack_overflow(addr); | |
| 7483 } | |
| 7484 // anything including and to the right of _finger | |
| 7485 // will be scanned as we iterate over the remainder of the | |
| 7486 // bit map | |
| 7487 } | |
| 7488 } | |
| 7489 | |
| 7490 PushOrMarkClosure::PushOrMarkClosure(CMSCollector* collector, | |
| 7491 MemRegion span, | |
| 7492 CMSBitMap* bitMap, CMSMarkStack* markStack, | |
| 7493 CMSMarkStack* revisitStack, | |
| 7494 HeapWord* finger, MarkFromRootsClosure* parent) : | |
| 935 | 7495 KlassRememberingOopClosure(collector, collector->ref_processor(), revisitStack), |
| 0 | 7496 _span(span), |
| 7497 _bitMap(bitMap), | |
| 7498 _markStack(markStack), | |
| 7499 _finger(finger), | |
| 935 | 7500 _parent(parent) |
| 0 | 7501 { } |
| 7502 | |
| 7503 Par_PushOrMarkClosure::Par_PushOrMarkClosure(CMSCollector* collector, | |
| 7504 MemRegion span, | |
| 7505 CMSBitMap* bit_map, | |
| 7506 OopTaskQueue* work_queue, | |
| 7507 CMSMarkStack* overflow_stack, | |
| 7508 CMSMarkStack* revisit_stack, | |
| 7509 HeapWord* finger, | |
| 7510 HeapWord** global_finger_addr, | |
| 7511 Par_MarkFromRootsClosure* parent) : | |
| 935 | 7512 Par_KlassRememberingOopClosure(collector, |
| 7513 collector->ref_processor(), | |
| 7514 revisit_stack), | |
| 0 | 7515 _whole_span(collector->_span), |
| 7516 _span(span), | |
| 7517 _bit_map(bit_map), | |
| 7518 _work_queue(work_queue), | |
| 7519 _overflow_stack(overflow_stack), | |
| 7520 _finger(finger), | |
| 7521 _global_finger_addr(global_finger_addr), | |
| 935 | 7522 _parent(parent) |
| 0 | 7523 { } |
| 7524 | |
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7525 // Assumes thread-safe access by callers, who are |
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7526 // responsible for mutual exclusion. |
| 0 | 7527 void CMSCollector::lower_restart_addr(HeapWord* low) { |
| 7528 assert(_span.contains(low), "Out of bounds addr"); | |
| 7529 if (_restart_addr == NULL) { | |
| 7530 _restart_addr = low; | |
| 7531 } else { | |
| 7532 _restart_addr = MIN2(_restart_addr, low); | |
| 7533 } | |
| 7534 } | |
| 7535 | |
| 7536 // Upon stack overflow, we discard (part of) the stack, | |
| 7537 // remembering the least address amongst those discarded | |
| 7538 // in CMSCollector's _restart_address. | |
| 7539 void PushOrMarkClosure::handle_stack_overflow(HeapWord* lost) { | |
| 7540 // Remember the least grey address discarded | |
| 7541 HeapWord* ra = (HeapWord*)_markStack->least_value(lost); | |
| 7542 _collector->lower_restart_addr(ra); | |
| 7543 _markStack->reset(); // discard stack contents | |
| 7544 _markStack->expand(); // expand the stack if possible | |
| 7545 } | |
| 7546 | |
| 7547 // Upon stack overflow, we discard (part of) the stack, | |
| 7548 // remembering the least address amongst those discarded | |
| 7549 // in CMSCollector's _restart_address. | |
| 7550 void Par_PushOrMarkClosure::handle_stack_overflow(HeapWord* lost) { | |
| 7551 // We need to do this under a mutex to prevent other | |
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7552 // workers from interfering with the work done below. |
| 0 | 7553 MutexLockerEx ml(_overflow_stack->par_lock(), |
| 7554 Mutex::_no_safepoint_check_flag); | |
| 7555 // Remember the least grey address discarded | |
| 7556 HeapWord* ra = (HeapWord*)_overflow_stack->least_value(lost); | |
| 7557 _collector->lower_restart_addr(ra); | |
| 7558 _overflow_stack->reset(); // discard stack contents | |
| 7559 _overflow_stack->expand(); // expand the stack if possible | |
| 7560 } | |
| 7561 | |
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7562 void PushOrMarkClosure::do_oop(oop obj) { |
| 0 | 7563 // Ignore mark word because we are running concurrent with mutators. |
|
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7564 assert(obj->is_oop_or_null(true), "expected an oop or NULL"); |
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7565 HeapWord* addr = (HeapWord*)obj; |
| 0 | 7566 if (_span.contains(addr) && !_bitMap->isMarked(addr)) { |
| 7567 // Oop lies in _span and isn't yet grey or black | |
| 7568 _bitMap->mark(addr); // now grey | |
| 7569 if (addr < _finger) { | |
| 7570 // the bit map iteration has already either passed, or | |
| 7571 // sampled, this bit in the bit map; we'll need to | |
| 7572 // use the marking stack to scan this oop's oops. | |
| 7573 bool simulate_overflow = false; | |
| 7574 NOT_PRODUCT( | |
| 7575 if (CMSMarkStackOverflowALot && | |
| 7576 _collector->simulate_overflow()) { | |
| 7577 // simulate a stack overflow | |
| 7578 simulate_overflow = true; | |
| 7579 } | |
| 7580 ) | |
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7581 if (simulate_overflow || !_markStack->push(obj)) { // stack overflow |
| 0 | 7582 if (PrintCMSStatistics != 0) { |
| 7583 gclog_or_tty->print_cr("CMS marking stack overflow (benign) at " | |
| 7584 SIZE_FORMAT, _markStack->capacity()); | |
| 7585 } | |
| 7586 assert(simulate_overflow || _markStack->isFull(), "Else push should have succeeded"); | |
| 7587 handle_stack_overflow(addr); | |
| 7588 } | |
| 7589 } | |
| 7590 // anything including and to the right of _finger | |
| 7591 // will be scanned as we iterate over the remainder of the | |
| 7592 // bit map | |
| 7593 do_yield_check(); | |
| 7594 } | |
| 7595 } | |
| 7596 | |
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7597 void PushOrMarkClosure::do_oop(oop* p) { PushOrMarkClosure::do_oop_work(p); } |
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7598 void PushOrMarkClosure::do_oop(narrowOop* p) { PushOrMarkClosure::do_oop_work(p); } |
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7599 |
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7600 void Par_PushOrMarkClosure::do_oop(oop obj) { |
| 0 | 7601 // Ignore mark word because we are running concurrent with mutators. |
|
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7602 assert(obj->is_oop_or_null(true), "expected an oop or NULL"); |
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7603 HeapWord* addr = (HeapWord*)obj; |
| 0 | 7604 if (_whole_span.contains(addr) && !_bit_map->isMarked(addr)) { |
| 7605 // Oop lies in _span and isn't yet grey or black | |
| 7606 // We read the global_finger (volatile read) strictly after marking oop | |
| 7607 bool res = _bit_map->par_mark(addr); // now grey | |
| 7608 volatile HeapWord** gfa = (volatile HeapWord**)_global_finger_addr; | |
| 7609 // Should we push this marked oop on our stack? | |
| 7610 // -- if someone else marked it, nothing to do | |
| 7611 // -- if target oop is above global finger nothing to do | |
| 7612 // -- if target oop is in chunk and above local finger | |
| 7613 // then nothing to do | |
| 7614 // -- else push on work queue | |
| 7615 if ( !res // someone else marked it, they will deal with it | |
| 7616 || (addr >= *gfa) // will be scanned in a later task | |
| 7617 || (_span.contains(addr) && addr >= _finger)) { // later in this chunk | |
| 7618 return; | |
| 7619 } | |
| 7620 // the bit map iteration has already either passed, or | |
| 7621 // sampled, this bit in the bit map; we'll need to | |
| 7622 // use the marking stack to scan this oop's oops. | |
| 7623 bool simulate_overflow = false; | |
| 7624 NOT_PRODUCT( | |
| 7625 if (CMSMarkStackOverflowALot && | |
| 7626 _collector->simulate_overflow()) { | |
| 7627 // simulate a stack overflow | |
| 7628 simulate_overflow = true; | |
| 7629 } | |
| 7630 ) | |
| 7631 if (simulate_overflow || | |
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7632 !(_work_queue->push(obj) || _overflow_stack->par_push(obj))) { |
| 0 | 7633 // stack overflow |
| 7634 if (PrintCMSStatistics != 0) { | |
| 7635 gclog_or_tty->print_cr("CMS marking stack overflow (benign) at " | |
| 7636 SIZE_FORMAT, _overflow_stack->capacity()); | |
| 7637 } | |
| 7638 // We cannot assert that the overflow stack is full because | |
| 7639 // it may have been emptied since. | |
| 7640 assert(simulate_overflow || | |
| 7641 _work_queue->size() == _work_queue->max_elems(), | |
| 7642 "Else push should have succeeded"); | |
| 7643 handle_stack_overflow(addr); | |
| 7644 } | |
| 7645 do_yield_check(); | |
| 7646 } | |
| 7647 } | |
| 7648 | |
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7649 void Par_PushOrMarkClosure::do_oop(oop* p) { Par_PushOrMarkClosure::do_oop_work(p); } |
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7650 void Par_PushOrMarkClosure::do_oop(narrowOop* p) { Par_PushOrMarkClosure::do_oop_work(p); } |
| 0 | 7651 |
| 935 | 7652 KlassRememberingOopClosure::KlassRememberingOopClosure(CMSCollector* collector, |
| 7653 ReferenceProcessor* rp, | |
| 7654 CMSMarkStack* revisit_stack) : | |
| 7655 OopClosure(rp), | |
| 7656 _collector(collector), | |
| 7657 _revisit_stack(revisit_stack), | |
| 7658 _should_remember_klasses(collector->should_unload_classes()) {} | |
| 7659 | |
| 0 | 7660 PushAndMarkClosure::PushAndMarkClosure(CMSCollector* collector, |
| 7661 MemRegion span, | |
| 7662 ReferenceProcessor* rp, | |
| 7663 CMSBitMap* bit_map, | |
| 7664 CMSBitMap* mod_union_table, | |
| 7665 CMSMarkStack* mark_stack, | |
| 7666 CMSMarkStack* revisit_stack, | |
| 7667 bool concurrent_precleaning): | |
| 935 | 7668 KlassRememberingOopClosure(collector, rp, revisit_stack), |
| 0 | 7669 _span(span), |
| 7670 _bit_map(bit_map), | |
| 7671 _mod_union_table(mod_union_table), | |
| 7672 _mark_stack(mark_stack), | |
| 935 | 7673 _concurrent_precleaning(concurrent_precleaning) |
| 0 | 7674 { |
| 7675 assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL"); | |
| 7676 } | |
| 7677 | |
| 7678 // Grey object rescan during pre-cleaning and second checkpoint phases -- | |
| 7679 // the non-parallel version (the parallel version appears further below.) | |
|
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7680 void PushAndMarkClosure::do_oop(oop obj) { |
|
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7681 // Ignore mark word verification. If during concurrent precleaning, |
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7682 // the object monitor may be locked. If during the checkpoint |
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7683 // phases, the object may already have been reached by a different |
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7684 // path and may be at the end of the global overflow list (so |
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7685 // the mark word may be NULL). |
|
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7686 assert(obj->is_oop_or_null(true /* ignore mark word */), |
| 0 | 7687 "expected an oop or NULL"); |
|
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7688 HeapWord* addr = (HeapWord*)obj; |
| 0 | 7689 // Check if oop points into the CMS generation |
| 7690 // and is not marked | |
| 7691 if (_span.contains(addr) && !_bit_map->isMarked(addr)) { | |
| 7692 // a white object ... | |
| 7693 _bit_map->mark(addr); // ... now grey | |
| 7694 // push on the marking stack (grey set) | |
| 7695 bool simulate_overflow = false; | |
| 7696 NOT_PRODUCT( | |
| 7697 if (CMSMarkStackOverflowALot && | |
| 7698 _collector->simulate_overflow()) { | |
| 7699 // simulate a stack overflow | |
| 7700 simulate_overflow = true; | |
| 7701 } | |
| 7702 ) | |
|
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7703 if (simulate_overflow || !_mark_stack->push(obj)) { |
| 0 | 7704 if (_concurrent_precleaning) { |
|
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7705 // During precleaning we can just dirty the appropriate card(s) |
| 0 | 7706 // in the mod union table, thus ensuring that the object remains |
|
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7707 // in the grey set and continue. In the case of object arrays |
|
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7708 // we need to dirty all of the cards that the object spans, |
|
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7709 // since the rescan of object arrays will be limited to the |
|
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|
7710 // dirty cards. |
|
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7711 // Note that no one can be intefering with us in this action |
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7712 // of dirtying the mod union table, so no locking or atomics |
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7713 // are required. |
|
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|
7714 if (obj->is_objArray()) { |
|
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7715 size_t sz = obj->size(); |
|
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|
7716 HeapWord* end_card_addr = (HeapWord*)round_to( |
|
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7717 (intptr_t)(addr+sz), CardTableModRefBS::card_size); |
|
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|
7718 MemRegion redirty_range = MemRegion(addr, end_card_addr); |
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|
7719 assert(!redirty_range.is_empty(), "Arithmetical tautology"); |
|
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7720 _mod_union_table->mark_range(redirty_range); |
|
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7721 } else { |
|
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|
7722 _mod_union_table->mark(addr); |
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7723 } |
| 0 | 7724 _collector->_ser_pmc_preclean_ovflw++; |
| 7725 } else { | |
| 7726 // During the remark phase, we need to remember this oop | |
| 7727 // in the overflow list. | |
|
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7728 _collector->push_on_overflow_list(obj); |
| 0 | 7729 _collector->_ser_pmc_remark_ovflw++; |
| 7730 } | |
| 7731 } | |
| 7732 } | |
| 7733 } | |
| 7734 | |
| 7735 Par_PushAndMarkClosure::Par_PushAndMarkClosure(CMSCollector* collector, | |
| 7736 MemRegion span, | |
| 7737 ReferenceProcessor* rp, | |
| 7738 CMSBitMap* bit_map, | |
| 7739 OopTaskQueue* work_queue, | |
| 7740 CMSMarkStack* revisit_stack): | |
| 935 | 7741 Par_KlassRememberingOopClosure(collector, rp, revisit_stack), |
| 0 | 7742 _span(span), |
| 7743 _bit_map(bit_map), | |
| 935 | 7744 _work_queue(work_queue) |
| 0 | 7745 { |
| 7746 assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL"); | |
| 7747 } | |
| 7748 | |
|
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7749 void PushAndMarkClosure::do_oop(oop* p) { PushAndMarkClosure::do_oop_work(p); } |
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7750 void PushAndMarkClosure::do_oop(narrowOop* p) { PushAndMarkClosure::do_oop_work(p); } |
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7751 |
| 0 | 7752 // Grey object rescan during second checkpoint phase -- |
| 7753 // the parallel version. | |
|
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7754 void Par_PushAndMarkClosure::do_oop(oop obj) { |
| 0 | 7755 // In the assert below, we ignore the mark word because |
| 7756 // this oop may point to an already visited object that is | |
| 7757 // on the overflow stack (in which case the mark word has | |
| 7758 // been hijacked for chaining into the overflow stack -- | |
| 7759 // if this is the last object in the overflow stack then | |
| 7760 // its mark word will be NULL). Because this object may | |
| 7761 // have been subsequently popped off the global overflow | |
| 7762 // stack, and the mark word possibly restored to the prototypical | |
| 7763 // value, by the time we get to examined this failing assert in | |
| 7764 // the debugger, is_oop_or_null(false) may subsequently start | |
| 7765 // to hold. | |
|
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7766 assert(obj->is_oop_or_null(true), |
| 0 | 7767 "expected an oop or NULL"); |
|
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7768 HeapWord* addr = (HeapWord*)obj; |
| 0 | 7769 // Check if oop points into the CMS generation |
| 7770 // and is not marked | |
| 7771 if (_span.contains(addr) && !_bit_map->isMarked(addr)) { | |
| 7772 // a white object ... | |
| 7773 // If we manage to "claim" the object, by being the | |
| 7774 // first thread to mark it, then we push it on our | |
| 7775 // marking stack | |
| 7776 if (_bit_map->par_mark(addr)) { // ... now grey | |
| 7777 // push on work queue (grey set) | |
| 7778 bool simulate_overflow = false; | |
| 7779 NOT_PRODUCT( | |
| 7780 if (CMSMarkStackOverflowALot && | |
| 7781 _collector->par_simulate_overflow()) { | |
| 7782 // simulate a stack overflow | |
| 7783 simulate_overflow = true; | |
| 7784 } | |
| 7785 ) | |
|
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7786 if (simulate_overflow || !_work_queue->push(obj)) { |
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7787 _collector->par_push_on_overflow_list(obj); |
| 0 | 7788 _collector->_par_pmc_remark_ovflw++; // imprecise OK: no need to CAS |
| 7789 } | |
| 7790 } // Else, some other thread got there first | |
| 7791 } | |
| 7792 } | |
| 7793 | |
|
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7794 void Par_PushAndMarkClosure::do_oop(oop* p) { Par_PushAndMarkClosure::do_oop_work(p); } |
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7795 void Par_PushAndMarkClosure::do_oop(narrowOop* p) { Par_PushAndMarkClosure::do_oop_work(p); } |
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7796 |
| 941 | 7797 void PushAndMarkClosure::remember_mdo(DataLayout* v) { |
| 7798 // TBD | |
| 7799 } | |
| 7800 | |
| 7801 void Par_PushAndMarkClosure::remember_mdo(DataLayout* v) { | |
| 7802 // TBD | |
| 7803 } | |
| 7804 | |
| 0 | 7805 void CMSPrecleanRefsYieldClosure::do_yield_work() { |
| 935 | 7806 DEBUG_ONLY(RememberKlassesChecker mux(false);) |
| 0 | 7807 Mutex* bml = _collector->bitMapLock(); |
| 7808 assert_lock_strong(bml); | |
| 7809 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 7810 "CMS thread should hold CMS token"); | |
| 7811 | |
| 7812 bml->unlock(); | |
| 7813 ConcurrentMarkSweepThread::desynchronize(true); | |
| 7814 | |
| 7815 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7816 | |
| 7817 _collector->stopTimer(); | |
| 7818 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 7819 if (PrintCMSStatistics != 0) { | |
| 7820 _collector->incrementYields(); | |
| 7821 } | |
| 7822 _collector->icms_wait(); | |
| 7823 | |
| 7824 // See the comment in coordinator_yield() | |
| 7825 for (unsigned i = 0; i < CMSYieldSleepCount && | |
| 7826 ConcurrentMarkSweepThread::should_yield() && | |
| 7827 !CMSCollector::foregroundGCIsActive(); ++i) { | |
| 7828 os::sleep(Thread::current(), 1, false); | |
| 7829 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7830 } | |
| 7831 | |
| 7832 ConcurrentMarkSweepThread::synchronize(true); | |
| 7833 bml->lock(); | |
| 7834 | |
| 7835 _collector->startTimer(); | |
| 7836 } | |
| 7837 | |
| 7838 bool CMSPrecleanRefsYieldClosure::should_return() { | |
| 7839 if (ConcurrentMarkSweepThread::should_yield()) { | |
| 7840 do_yield_work(); | |
| 7841 } | |
| 7842 return _collector->foregroundGCIsActive(); | |
| 7843 } | |
| 7844 | |
| 7845 void MarkFromDirtyCardsClosure::do_MemRegion(MemRegion mr) { | |
| 7846 assert(((size_t)mr.start())%CardTableModRefBS::card_size_in_words == 0, | |
| 7847 "mr should be aligned to start at a card boundary"); | |
| 7848 // We'd like to assert: | |
| 7849 // assert(mr.word_size()%CardTableModRefBS::card_size_in_words == 0, | |
| 7850 // "mr should be a range of cards"); | |
| 7851 // However, that would be too strong in one case -- the last | |
| 7852 // partition ends at _unallocated_block which, in general, can be | |
| 7853 // an arbitrary boundary, not necessarily card aligned. | |
| 7854 if (PrintCMSStatistics != 0) { | |
| 7855 _num_dirty_cards += | |
| 7856 mr.word_size()/CardTableModRefBS::card_size_in_words; | |
| 7857 } | |
| 7858 _space->object_iterate_mem(mr, &_scan_cl); | |
| 7859 } | |
| 7860 | |
| 7861 SweepClosure::SweepClosure(CMSCollector* collector, | |
| 7862 ConcurrentMarkSweepGeneration* g, | |
| 7863 CMSBitMap* bitMap, bool should_yield) : | |
| 7864 _collector(collector), | |
| 7865 _g(g), | |
| 7866 _sp(g->cmsSpace()), | |
| 7867 _limit(_sp->sweep_limit()), | |
| 7868 _freelistLock(_sp->freelistLock()), | |
| 7869 _bitMap(bitMap), | |
| 7870 _yield(should_yield), | |
| 7871 _inFreeRange(false), // No free range at beginning of sweep | |
| 7872 _freeRangeInFreeLists(false), // No free range at beginning of sweep | |
| 7873 _lastFreeRangeCoalesced(false), | |
| 7874 _freeFinger(g->used_region().start()) | |
| 7875 { | |
| 7876 NOT_PRODUCT( | |
| 7877 _numObjectsFreed = 0; | |
| 7878 _numWordsFreed = 0; | |
| 7879 _numObjectsLive = 0; | |
| 7880 _numWordsLive = 0; | |
| 7881 _numObjectsAlreadyFree = 0; | |
| 7882 _numWordsAlreadyFree = 0; | |
| 7883 _last_fc = NULL; | |
| 7884 | |
| 7885 _sp->initializeIndexedFreeListArrayReturnedBytes(); | |
| 7886 _sp->dictionary()->initializeDictReturnedBytes(); | |
| 7887 ) | |
| 7888 assert(_limit >= _sp->bottom() && _limit <= _sp->end(), | |
| 7889 "sweep _limit out of bounds"); | |
| 7890 if (CMSTraceSweeper) { | |
|
3746
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|
7891 gclog_or_tty->print_cr("\n====================\nStarting new sweep with limit " PTR_FORMAT, |
|
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|
7892 _limit); |
|
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|
7893 } |
|
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|
7894 } |
|
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|
7895 |
|
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|
7896 void SweepClosure::print_on(outputStream* st) const { |
|
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|
7897 tty->print_cr("_sp = [" PTR_FORMAT "," PTR_FORMAT ")", |
|
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|
7898 _sp->bottom(), _sp->end()); |
|
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|
7899 tty->print_cr("_limit = " PTR_FORMAT, _limit); |
|
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|
7900 tty->print_cr("_freeFinger = " PTR_FORMAT, _freeFinger); |
|
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|
7901 NOT_PRODUCT(tty->print_cr("_last_fc = " PTR_FORMAT, _last_fc);) |
|
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|
7902 tty->print_cr("_inFreeRange = %d, _freeRangeInFreeLists = %d, _lastFreeRangeCoalesced = %d", |
|
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|
7903 _inFreeRange, _freeRangeInFreeLists, _lastFreeRangeCoalesced); |
|
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|
7904 } |
|
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|
7905 |
|
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|
7906 #ifndef PRODUCT |
|
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|
7907 // Assertion checking only: no useful work in product mode -- |
|
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|
7908 // however, if any of the flags below become product flags, |
|
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|
7909 // you may need to review this code to see if it needs to be |
|
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|
7910 // enabled in product mode. |
| 0 | 7911 SweepClosure::~SweepClosure() { |
| 7912 assert_lock_strong(_freelistLock); | |
|
2132
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|
7913 assert(_limit >= _sp->bottom() && _limit <= _sp->end(), |
|
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|
7914 "sweep _limit out of bounds"); |
| 0 | 7915 if (inFreeRange()) { |
|
3746
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|
7916 warning("inFreeRange() should have been reset; dumping state of SweepClosure"); |
|
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|
7917 print(); |
|
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|
7918 ShouldNotReachHere(); |
|
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|
7919 } |
|
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|
7920 if (Verbose && PrintGC) { |
|
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|
7921 gclog_or_tty->print("Collected "SIZE_FORMAT" objects, " SIZE_FORMAT " bytes", |
|
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|
7922 _numObjectsFreed, _numWordsFreed*sizeof(HeapWord)); |
|
537a4053b0f9
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|
7923 gclog_or_tty->print_cr("\nLive "SIZE_FORMAT" objects, " |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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3356
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|
7924 SIZE_FORMAT" bytes " |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
7925 "Already free "SIZE_FORMAT" objects, "SIZE_FORMAT" bytes", |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
7926 _numObjectsLive, _numWordsLive*sizeof(HeapWord), |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
7927 _numObjectsAlreadyFree, _numWordsAlreadyFree*sizeof(HeapWord)); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
7928 size_t totalBytes = (_numWordsFreed + _numWordsLive + _numWordsAlreadyFree) |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
7929 * sizeof(HeapWord); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
7930 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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|
7931 |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
7932 if (PrintCMSStatistics && CMSVerifyReturnedBytes) { |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
7933 size_t indexListReturnedBytes = _sp->sumIndexedFreeListArrayReturnedBytes(); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
7934 size_t dictReturnedBytes = _sp->dictionary()->sumDictReturnedBytes(); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
7935 size_t returnedBytes = indexListReturnedBytes + dictReturnedBytes; |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
7936 gclog_or_tty->print("Returned "SIZE_FORMAT" bytes", returnedBytes); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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parents:
3356
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|
7937 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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|
7938 indexListReturnedBytes); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
7939 gclog_or_tty->print_cr(" Dictionary Returned "SIZE_FORMAT" bytes", |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
7940 dictReturnedBytes); |
|
537a4053b0f9
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|
7941 } |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
7942 } |
| 0 | 7943 if (CMSTraceSweeper) { |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
7944 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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|
7945 _limit); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
7946 } |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
7947 } |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
7948 #endif // PRODUCT |
| 0 | 7949 |
| 7950 void SweepClosure::initialize_free_range(HeapWord* freeFinger, | |
| 7951 bool freeRangeInFreeLists) { | |
| 7952 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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|
7953 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
|
7954 freeFinger, freeRangeInFreeLists); |
| 0 | 7955 } |
| 7956 assert(!inFreeRange(), "Trampling existing free range"); | |
| 7957 set_inFreeRange(true); | |
| 7958 set_lastFreeRangeCoalesced(false); | |
| 7959 | |
| 7960 set_freeFinger(freeFinger); | |
| 7961 set_freeRangeInFreeLists(freeRangeInFreeLists); | |
| 7962 if (CMSTestInFreeList) { | |
| 7963 if (freeRangeInFreeLists) { | |
| 7964 FreeChunk* fc = (FreeChunk*) freeFinger; | |
| 7965 assert(fc->isFree(), "A chunk on the free list should be free."); | |
| 7966 assert(fc->size() > 0, "Free range should have a size"); | |
| 7967 assert(_sp->verifyChunkInFreeLists(fc), "Chunk is not in free lists"); | |
| 7968 } | |
| 7969 } | |
| 7970 } | |
| 7971 | |
| 7972 // Note that the sweeper runs concurrently with mutators. Thus, | |
| 7973 // it is possible for direct allocation in this generation to happen | |
| 7974 // in the middle of the sweep. Note that the sweeper also coalesces | |
| 7975 // contiguous free blocks. Thus, unless the sweeper and the allocator | |
| 7976 // synchronize appropriately freshly allocated blocks may get swept up. | |
| 7977 // This is accomplished by the sweeper locking the free lists while | |
| 7978 // it is sweeping. Thus blocks that are determined to be free are | |
| 7979 // indeed free. There is however one additional complication: | |
| 7980 // blocks that have been allocated since the final checkpoint and | |
| 7981 // mark, will not have been marked and so would be treated as | |
| 7982 // unreachable and swept up. To prevent this, the allocator marks | |
| 7983 // the bit map when allocating during the sweep phase. This leads, | |
| 7984 // however, to a further complication -- objects may have been allocated | |
| 7985 // but not yet initialized -- in the sense that the header isn't yet | |
| 7986 // installed. The sweeper can not then determine the size of the block | |
| 7987 // in order to skip over it. To deal with this case, we use a technique | |
| 7988 // (due to Printezis) to encode such uninitialized block sizes in the | |
| 7989 // bit map. Since the bit map uses a bit per every HeapWord, but the | |
| 7990 // CMS generation has a minimum object size of 3 HeapWords, it follows | |
| 7991 // that "normal marks" won't be adjacent in the bit map (there will | |
| 7992 // always be at least two 0 bits between successive 1 bits). We make use | |
| 7993 // of these "unused" bits to represent uninitialized blocks -- the bit | |
| 7994 // corresponding to the start of the uninitialized object and the next | |
| 7995 // bit are both set. Finally, a 1 bit marks the end of the object that | |
| 7996 // started with the two consecutive 1 bits to indicate its potentially | |
| 7997 // uninitialized state. | |
| 7998 | |
| 7999 size_t SweepClosure::do_blk_careful(HeapWord* addr) { | |
| 8000 FreeChunk* fc = (FreeChunk*)addr; | |
| 8001 size_t res; | |
| 8002 | |
|
1720
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
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1716
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|
8003 // 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
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|
8004 // 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
|
8005 // we started the sweep, it may no longer be one because heap expansion |
|
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
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parents:
1716
diff
changeset
|
8006 // may have caused us to coalesce the block ending at the address _limit |
|
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
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1716
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|
8007 // 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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|
8008 // 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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|
8009 // 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
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|
8010 if (addr >= _limit) { // we have swept up to or past the limit: finish up |
| 0 | 8011 assert(_limit >= _sp->bottom() && _limit <= _sp->end(), |
| 8012 "sweep _limit out of bounds"); | |
|
1720
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
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parents:
1716
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|
8013 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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|
8014 // 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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|
8015 // coalesced chunk to the appropriate free list. |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
changeset
|
8016 if (inFreeRange()) { |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8017 assert(freeFinger() >= _sp->bottom() && freeFinger() < _limit, |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8018 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
changeset
|
8019 flush_cur_free_chunk(freeFinger(), |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
changeset
|
8020 pointer_delta(addr, freeFinger())); |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
changeset
|
8021 if (CMSTraceSweeper) { |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8022 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
|
8023 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
changeset
|
8024 "[coalesced:"SIZE_FORMAT"]\n", |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8025 freeFinger(), pointer_delta(addr, freeFinger()), |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8026 lastFreeRangeCoalesced()); |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8027 } |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8028 } |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8029 |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8030 // help the iterator loop finish |
|
1720
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
parents:
1716
diff
changeset
|
8031 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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|
8032 } |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8033 |
|
1720
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
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1716
diff
changeset
|
8034 assert(addr < _limit, "sweep invariant"); |
| 0 | 8035 // check if we should yield |
| 8036 do_yield_check(addr); | |
| 8037 if (fc->isFree()) { | |
| 8038 // Chunk that is already free | |
| 8039 res = fc->size(); | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
changeset
|
8040 do_already_free_chunk(fc); |
| 0 | 8041 debug_only(_sp->verifyFreeLists()); |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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changeset
|
8042 // If we flush the chunk at hand in lookahead_and_flush() |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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3356
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|
8043 // and it's coalesced with a preceding chunk, then the |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8044 // process of "mangling" the payload of the coalesced block |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8045 // will cause erasure of the size information from the |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8046 // (erstwhile) header of all the coalesced blocks but the |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8047 // first, so the first disjunct in the assert will not hold |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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3356
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|
8048 // 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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|
8049 // will hold). |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8050 assert(res == fc->size() || ((HeapWord*)fc) + res >= _limit, |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8051 "Otherwise the size info doesn't change at this step"); |
| 0 | 8052 NOT_PRODUCT( |
| 8053 _numObjectsAlreadyFree++; | |
| 8054 _numWordsAlreadyFree += res; | |
| 8055 ) | |
| 8056 NOT_PRODUCT(_last_fc = fc;) | |
| 8057 } else if (!_bitMap->isMarked(addr)) { | |
| 8058 // Chunk is fresh garbage | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
changeset
|
8059 res = do_garbage_chunk(fc); |
| 0 | 8060 debug_only(_sp->verifyFreeLists()); |
| 8061 NOT_PRODUCT( | |
| 8062 _numObjectsFreed++; | |
| 8063 _numWordsFreed += res; | |
| 8064 ) | |
| 8065 } else { | |
| 8066 // Chunk that is alive. | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
changeset
|
8067 res = do_live_chunk(fc); |
| 0 | 8068 debug_only(_sp->verifyFreeLists()); |
| 8069 NOT_PRODUCT( | |
| 8070 _numObjectsLive++; | |
| 8071 _numWordsLive += res; | |
| 8072 ) | |
| 8073 } | |
| 8074 return res; | |
| 8075 } | |
| 8076 | |
| 8077 // For the smart allocation, record following | |
| 8078 // split deaths - a free chunk is removed from its free list because | |
| 8079 // it is being split into two or more chunks. | |
| 8080 // split birth - a free chunk is being added to its free list because | |
| 8081 // a larger free chunk has been split and resulted in this free chunk. | |
| 8082 // coal death - a free chunk is being removed from its free list because | |
| 8083 // it is being coalesced into a large free chunk. | |
| 8084 // coal birth - a free chunk is being added to its free list because | |
| 8085 // it was created when two or more free chunks where coalesced into | |
| 8086 // this free chunk. | |
| 8087 // | |
| 8088 // These statistics are used to determine the desired number of free | |
| 8089 // chunks of a given size. The desired number is chosen to be relative | |
| 8090 // to the end of a CMS sweep. The desired number at the end of a sweep | |
| 8091 // is the | |
| 8092 // count-at-end-of-previous-sweep (an amount that was enough) | |
| 8093 // - count-at-beginning-of-current-sweep (the excess) | |
| 8094 // + split-births (gains in this size during interval) | |
| 8095 // - split-deaths (demands on this size during interval) | |
| 8096 // where the interval is from the end of one sweep to the end of the | |
| 8097 // next. | |
| 8098 // | |
| 8099 // When sweeping the sweeper maintains an accumulated chunk which is | |
| 8100 // the chunk that is made up of chunks that have been coalesced. That | |
| 8101 // will be termed the left-hand chunk. A new chunk of garbage that | |
| 8102 // is being considered for coalescing will be referred to as the | |
| 8103 // right-hand chunk. | |
| 8104 // | |
| 8105 // When making a decision on whether to coalesce a right-hand chunk with | |
| 8106 // the current left-hand chunk, the current count vs. the desired count | |
| 8107 // of the left-hand chunk is considered. Also if the right-hand chunk | |
| 8108 // is near the large chunk at the end of the heap (see | |
| 8109 // ConcurrentMarkSweepGeneration::isNearLargestChunk()), then the | |
| 8110 // left-hand chunk is coalesced. | |
| 8111 // | |
| 8112 // When making a decision about whether to split a chunk, the desired count | |
| 8113 // vs. the current count of the candidate to be split is also considered. | |
| 8114 // If the candidate is underpopulated (currently fewer chunks than desired) | |
| 8115 // a chunk of an overpopulated (currently more chunks than desired) size may | |
| 8116 // be chosen. The "hint" associated with a free list, if non-null, points | |
| 8117 // to a free list which may be overpopulated. | |
| 8118 // | |
| 8119 | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
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|
8120 void SweepClosure::do_already_free_chunk(FreeChunk* fc) { |
|
3746
537a4053b0f9
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changeset
|
8121 const size_t size = fc->size(); |
| 0 | 8122 // Chunks that cannot be coalesced are not in the |
| 8123 // free lists. | |
| 8124 if (CMSTestInFreeList && !fc->cantCoalesce()) { | |
| 8125 assert(_sp->verifyChunkInFreeLists(fc), | |
| 8126 "free chunk should be in free lists"); | |
| 8127 } | |
| 8128 // a chunk that is already free, should not have been | |
| 8129 // marked in the bit map | |
|
3746
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|
8130 HeapWord* const addr = (HeapWord*) fc; |
| 0 | 8131 assert(!_bitMap->isMarked(addr), "free chunk should be unmarked"); |
| 8132 // Verify that the bit map has no bits marked between | |
| 8133 // addr and purported end of this block. | |
| 8134 _bitMap->verifyNoOneBitsInRange(addr + 1, addr + size); | |
| 8135 | |
|
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|
8136 // Some chunks cannot be coalesced under any circumstances. |
| 0 | 8137 // See the definition of cantCoalesce(). |
| 8138 if (!fc->cantCoalesce()) { | |
| 8139 // This chunk can potentially be coalesced. | |
| 8140 if (_sp->adaptive_freelists()) { | |
| 8141 // All the work is done in | |
|
2132
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|
8142 do_post_free_or_garbage_chunk(fc, size); |
| 0 | 8143 } else { // Not adaptive free lists |
| 8144 // this is a free chunk that can potentially be coalesced by the sweeper; | |
| 8145 if (!inFreeRange()) { | |
| 8146 // if the next chunk is a free block that can't be coalesced | |
| 8147 // it doesn't make sense to remove this chunk from the free lists | |
| 8148 FreeChunk* nextChunk = (FreeChunk*)(addr + size); | |
|
2136
c91cc404ca46
7011940: iCMS: SIGSEGV in SweepClosure::do_already_free_chunk(FreeChunk*)+0x360
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2132
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changeset
|
8149 assert((HeapWord*)nextChunk <= _sp->end(), "Chunk size out of bounds?"); |
|
c91cc404ca46
7011940: iCMS: SIGSEGV in SweepClosure::do_already_free_chunk(FreeChunk*)+0x360
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parents:
2132
diff
changeset
|
8150 if ((HeapWord*)nextChunk < _sp->end() && // There is another free chunk to the right ... |
|
c91cc404ca46
7011940: iCMS: SIGSEGV in SweepClosure::do_already_free_chunk(FreeChunk*)+0x360
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2132
diff
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|
8151 nextChunk->isFree() && // ... which is free... |
|
c91cc404ca46
7011940: iCMS: SIGSEGV in SweepClosure::do_already_free_chunk(FreeChunk*)+0x360
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|
8152 nextChunk->cantCoalesce()) { // ... but can't be coalesced |
| 0 | 8153 // nothing to do |
| 8154 } else { | |
| 8155 // Potentially the start of a new free range: | |
| 8156 // Don't eagerly remove it from the free lists. | |
| 8157 // No need to remove it if it will just be put | |
| 8158 // back again. (Also from a pragmatic point of view | |
| 8159 // if it is a free block in a region that is beyond | |
| 8160 // any allocated blocks, an assertion will fail) | |
| 8161 // Remember the start of a free run. | |
| 8162 initialize_free_range(addr, true); | |
| 8163 // end - can coalesce with next chunk | |
| 8164 } | |
| 8165 } else { | |
| 8166 // the midst of a free range, we are coalescing | |
|
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changeset
|
8167 print_free_block_coalesced(fc); |
| 0 | 8168 if (CMSTraceSweeper) { |
| 8169 gclog_or_tty->print(" -- pick up free block 0x%x (%d)\n", fc, size); | |
| 8170 } | |
| 8171 // remove it from the free lists | |
| 8172 _sp->removeFreeChunkFromFreeLists(fc); | |
| 8173 set_lastFreeRangeCoalesced(true); | |
| 8174 // If the chunk is being coalesced and the current free range is | |
| 8175 // in the free lists, remove the current free range so that it | |
| 8176 // will be returned to the free lists in its entirety - all | |
| 8177 // the coalesced pieces included. | |
| 8178 if (freeRangeInFreeLists()) { | |
| 8179 FreeChunk* ffc = (FreeChunk*) freeFinger(); | |
| 8180 assert(ffc->size() == pointer_delta(addr, freeFinger()), | |
| 8181 "Size of free range is inconsistent with chunk size."); | |
| 8182 if (CMSTestInFreeList) { | |
| 8183 assert(_sp->verifyChunkInFreeLists(ffc), | |
| 8184 "free range is not in free lists"); | |
| 8185 } | |
| 8186 _sp->removeFreeChunkFromFreeLists(ffc); | |
| 8187 set_freeRangeInFreeLists(false); | |
| 8188 } | |
| 8189 } | |
| 8190 } | |
|
3746
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changeset
|
8191 // Note that if the chunk is not coalescable (the else arm |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8192 // below), we unconditionally flush, without needing to do |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8193 // a "lookahead," as we do below. |
|
537a4053b0f9
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changeset
|
8194 if (inFreeRange()) lookahead_and_flush(fc, size); |
| 0 | 8195 } else { |
| 8196 // Code path common to both original and adaptive free lists. | |
| 8197 | |
| 8198 // cant coalesce with previous block; this should be treated | |
| 8199 // as the end of a free run if any | |
| 8200 if (inFreeRange()) { | |
| 8201 // we kicked some butt; time to pick up the garbage | |
|
2132
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1994
diff
changeset
|
8202 assert(freeFinger() < addr, "freeFinger points too high"); |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
changeset
|
8203 flush_cur_free_chunk(freeFinger(), pointer_delta(addr, freeFinger())); |
| 0 | 8204 } |
| 8205 // else, nothing to do, just continue | |
| 8206 } | |
| 8207 } | |
| 8208 | |
|
2132
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1994
diff
changeset
|
8209 size_t SweepClosure::do_garbage_chunk(FreeChunk* fc) { |
| 0 | 8210 // This is a chunk of garbage. It is not in any free list. |
| 8211 // Add it to a free list or let it possibly be coalesced into | |
| 8212 // a larger chunk. | |
|
3746
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parents:
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changeset
|
8213 HeapWord* const addr = (HeapWord*) fc; |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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parents:
3356
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changeset
|
8214 const size_t size = CompactibleFreeListSpace::adjustObjectSize(oop(addr)->size()); |
| 0 | 8215 |
| 8216 if (_sp->adaptive_freelists()) { | |
| 8217 // Verify that the bit map has no bits marked between | |
| 8218 // addr and purported end of just dead object. | |
| 8219 _bitMap->verifyNoOneBitsInRange(addr + 1, addr + size); | |
| 8220 | |
|
2132
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1994
diff
changeset
|
8221 do_post_free_or_garbage_chunk(fc, size); |
| 0 | 8222 } else { |
| 8223 if (!inFreeRange()) { | |
| 8224 // start of a new free range | |
| 8225 assert(size > 0, "A free range should have a size"); | |
| 8226 initialize_free_range(addr, false); | |
| 8227 } else { | |
| 8228 // this will be swept up when we hit the end of the | |
| 8229 // free range | |
| 8230 if (CMSTraceSweeper) { | |
| 8231 gclog_or_tty->print(" -- pick up garbage 0x%x (%d) \n", fc, size); | |
| 8232 } | |
| 8233 // If the chunk is being coalesced and the current free range is | |
| 8234 // in the free lists, remove the current free range so that it | |
| 8235 // will be returned to the free lists in its entirety - all | |
| 8236 // the coalesced pieces included. | |
| 8237 if (freeRangeInFreeLists()) { | |
| 8238 FreeChunk* ffc = (FreeChunk*)freeFinger(); | |
| 8239 assert(ffc->size() == pointer_delta(addr, freeFinger()), | |
| 8240 "Size of free range is inconsistent with chunk size."); | |
| 8241 if (CMSTestInFreeList) { | |
| 8242 assert(_sp->verifyChunkInFreeLists(ffc), | |
| 8243 "free range is not in free lists"); | |
| 8244 } | |
| 8245 _sp->removeFreeChunkFromFreeLists(ffc); | |
| 8246 set_freeRangeInFreeLists(false); | |
| 8247 } | |
| 8248 set_lastFreeRangeCoalesced(true); | |
| 8249 } | |
| 8250 // this will be swept up when we hit the end of the free range | |
| 8251 | |
| 8252 // Verify that the bit map has no bits marked between | |
| 8253 // addr and purported end of just dead object. | |
| 8254 _bitMap->verifyNoOneBitsInRange(addr + 1, addr + size); | |
| 8255 } | |
|
3746
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parents:
3356
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changeset
|
8256 assert(_limit >= addr + size, |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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parents:
3356
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changeset
|
8257 "A freshly garbage chunk can't possibly straddle over _limit"); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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parents:
3356
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changeset
|
8258 if (inFreeRange()) lookahead_and_flush(fc, size); |
| 0 | 8259 return size; |
| 8260 } | |
| 8261 | |
|
2132
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1994
diff
changeset
|
8262 size_t SweepClosure::do_live_chunk(FreeChunk* fc) { |
| 0 | 8263 HeapWord* addr = (HeapWord*) fc; |
| 8264 // The sweeper has just found a live object. Return any accumulated | |
| 8265 // left hand chunk to the free lists. | |
| 8266 if (inFreeRange()) { | |
|
2132
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1994
diff
changeset
|
8267 assert(freeFinger() < addr, "freeFinger points too high"); |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8268 flush_cur_free_chunk(freeFinger(), pointer_delta(addr, freeFinger())); |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8269 } |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8270 |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8271 // This object is live: we'd normally expect this to be |
| 0 | 8272 // an oop, and like to assert the following: |
| 8273 // assert(oop(addr)->is_oop(), "live block should be an oop"); | |
| 8274 // However, as we commented above, this may be an object whose | |
| 8275 // header hasn't yet been initialized. | |
| 8276 size_t size; | |
| 8277 assert(_bitMap->isMarked(addr), "Tautology for this control point"); | |
| 8278 if (_bitMap->isMarked(addr + 1)) { | |
| 8279 // Determine the size from the bit map, rather than trying to | |
| 8280 // compute it from the object header. | |
| 8281 HeapWord* nextOneAddr = _bitMap->getNextMarkedWordAddress(addr + 2); | |
| 8282 size = pointer_delta(nextOneAddr + 1, addr); | |
| 8283 assert(size == CompactibleFreeListSpace::adjustObjectSize(size), | |
| 8284 "alignment problem"); | |
| 8285 | |
|
2132
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ysr
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1994
diff
changeset
|
8286 #ifdef DEBUG |
| 187 | 8287 if (oop(addr)->klass_or_null() != NULL && |
|
94
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
8288 ( !_collector->should_unload_classes() |
|
518
0af8b0718fc9
6692899: CMS: many vm.parallel_class_loading tests fail with assert "missing Printezis mark"
jmasa
parents:
517
diff
changeset
|
8289 || (oop(addr)->is_parsable()) && |
|
0af8b0718fc9
6692899: CMS: many vm.parallel_class_loading tests fail with assert "missing Printezis mark"
jmasa
parents:
517
diff
changeset
|
8290 oop(addr)->is_conc_safe())) { |
| 0 | 8291 // Ignore mark word because we are running concurrent with mutators |
| 8292 assert(oop(addr)->is_oop(true), "live block should be an oop"); | |
|
518
0af8b0718fc9
6692899: CMS: many vm.parallel_class_loading tests fail with assert "missing Printezis mark"
jmasa
parents:
517
diff
changeset
|
8293 // is_conc_safe is checked before performing this assertion |
|
0af8b0718fc9
6692899: CMS: many vm.parallel_class_loading tests fail with assert "missing Printezis mark"
jmasa
parents:
517
diff
changeset
|
8294 // because an object that is not is_conc_safe may yet have |
|
0af8b0718fc9
6692899: CMS: many vm.parallel_class_loading tests fail with assert "missing Printezis mark"
jmasa
parents:
517
diff
changeset
|
8295 // the return from size() correct. |
| 0 | 8296 assert(size == |
| 8297 CompactibleFreeListSpace::adjustObjectSize(oop(addr)->size()), | |
| 8298 "P-mark and computed size do not agree"); | |
| 8299 } | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8300 #endif |
| 0 | 8301 |
| 8302 } else { | |
| 8303 // This should be an initialized object that's alive. | |
| 187 | 8304 assert(oop(addr)->klass_or_null() != NULL && |
|
94
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
8305 (!_collector->should_unload_classes() |
| 0 | 8306 || oop(addr)->is_parsable()), |
| 8307 "Should be an initialized object"); | |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8308 // Note that there are objects used during class redefinition, |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8309 // e.g. merge_cp in VM_RedefineClasses::merge_cp_and_rewrite(), |
|
518
0af8b0718fc9
6692899: CMS: many vm.parallel_class_loading tests fail with assert "missing Printezis mark"
jmasa
parents:
517
diff
changeset
|
8310 // which are discarded with their is_conc_safe state still |
|
0af8b0718fc9
6692899: CMS: many vm.parallel_class_loading tests fail with assert "missing Printezis mark"
jmasa
parents:
517
diff
changeset
|
8311 // false. These object may be floating garbage so may be |
|
0af8b0718fc9
6692899: CMS: many vm.parallel_class_loading tests fail with assert "missing Printezis mark"
jmasa
parents:
517
diff
changeset
|
8312 // seen here. If they are floating garbage their size |
|
0af8b0718fc9
6692899: CMS: many vm.parallel_class_loading tests fail with assert "missing Printezis mark"
jmasa
parents:
517
diff
changeset
|
8313 // should be attainable from their klass. Do not that |
|
0af8b0718fc9
6692899: CMS: many vm.parallel_class_loading tests fail with assert "missing Printezis mark"
jmasa
parents:
517
diff
changeset
|
8314 // is_conc_safe() is true for oop(addr). |
| 0 | 8315 // Ignore mark word because we are running concurrent with mutators |
| 8316 assert(oop(addr)->is_oop(true), "live block should be an oop"); | |
| 8317 // Verify that the bit map has no bits marked between | |
| 8318 // addr and purported end of this block. | |
| 8319 size = CompactibleFreeListSpace::adjustObjectSize(oop(addr)->size()); | |
| 8320 assert(size >= 3, "Necessary for Printezis marks to work"); | |
| 8321 assert(!_bitMap->isMarked(addr+1), "Tautology for this control point"); | |
| 8322 DEBUG_ONLY(_bitMap->verifyNoOneBitsInRange(addr+2, addr+size);) | |
| 8323 } | |
| 8324 return size; | |
| 8325 } | |
| 8326 | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8327 void SweepClosure::do_post_free_or_garbage_chunk(FreeChunk* fc, |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8328 size_t chunkSize) { |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8329 // do_post_free_or_garbage_chunk() should only be called in the case |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8330 // of the adaptive free list allocator. |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8331 const bool fcInFreeLists = fc->isFree(); |
| 0 | 8332 assert(_sp->adaptive_freelists(), "Should only be used in this case."); |
| 8333 assert((HeapWord*)fc <= _limit, "sweep invariant"); | |
| 8334 if (CMSTestInFreeList && fcInFreeLists) { | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8335 assert(_sp->verifyChunkInFreeLists(fc), "free chunk is not in free lists"); |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8336 } |
| 0 | 8337 |
| 8338 if (CMSTraceSweeper) { | |
| 8339 gclog_or_tty->print_cr(" -- pick up another chunk at 0x%x (%d)", fc, chunkSize); | |
| 8340 } | |
| 8341 | |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8342 HeapWord* const fc_addr = (HeapWord*) fc; |
| 0 | 8343 |
| 8344 bool coalesce; | |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8345 const size_t left = pointer_delta(fc_addr, freeFinger()); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8346 const size_t right = chunkSize; |
| 0 | 8347 switch (FLSCoalescePolicy) { |
| 8348 // numeric value forms a coalition aggressiveness metric | |
| 8349 case 0: { // never coalesce | |
| 8350 coalesce = false; | |
| 8351 break; | |
| 8352 } | |
| 8353 case 1: { // coalesce if left & right chunks on overpopulated lists | |
| 8354 coalesce = _sp->coalOverPopulated(left) && | |
| 8355 _sp->coalOverPopulated(right); | |
| 8356 break; | |
| 8357 } | |
| 8358 case 2: { // coalesce if left chunk on overpopulated list (default) | |
| 8359 coalesce = _sp->coalOverPopulated(left); | |
| 8360 break; | |
| 8361 } | |
| 8362 case 3: { // coalesce if left OR right chunk on overpopulated list | |
| 8363 coalesce = _sp->coalOverPopulated(left) || | |
| 8364 _sp->coalOverPopulated(right); | |
| 8365 break; | |
| 8366 } | |
| 8367 case 4: { // always coalesce | |
| 8368 coalesce = true; | |
| 8369 break; | |
| 8370 } | |
| 8371 default: | |
| 8372 ShouldNotReachHere(); | |
| 8373 } | |
| 8374 | |
| 8375 // Should the current free range be coalesced? | |
| 8376 // If the chunk is in a free range and either we decided to coalesce above | |
| 8377 // or the chunk is near the large block at the end of the heap | |
| 8378 // (isNearLargestChunk() returns true), then coalesce this chunk. | |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
diff
changeset
|
8379 const bool doCoalesce = inFreeRange() |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8380 && (coalesce || _g->isNearLargestChunk(fc_addr)); |
| 0 | 8381 if (doCoalesce) { |
| 8382 // Coalesce the current free range on the left with the new | |
| 8383 // chunk on the right. If either is on a free list, | |
| 8384 // it must be removed from the list and stashed in the closure. | |
| 8385 if (freeRangeInFreeLists()) { | |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8386 FreeChunk* const ffc = (FreeChunk*)freeFinger(); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8387 assert(ffc->size() == pointer_delta(fc_addr, freeFinger()), |
| 0 | 8388 "Size of free range is inconsistent with chunk size."); |
| 8389 if (CMSTestInFreeList) { | |
| 8390 assert(_sp->verifyChunkInFreeLists(ffc), | |
| 8391 "Chunk is not in free lists"); | |
| 8392 } | |
| 8393 _sp->coalDeath(ffc->size()); | |
| 8394 _sp->removeFreeChunkFromFreeLists(ffc); | |
| 8395 set_freeRangeInFreeLists(false); | |
| 8396 } | |
| 8397 if (fcInFreeLists) { | |
| 8398 _sp->coalDeath(chunkSize); | |
| 8399 assert(fc->size() == chunkSize, | |
| 8400 "The chunk has the wrong size or is not in the free lists"); | |
| 8401 _sp->removeFreeChunkFromFreeLists(fc); | |
| 8402 } | |
| 8403 set_lastFreeRangeCoalesced(true); | |
|
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|
8404 print_free_block_coalesced(fc); |
| 0 | 8405 } else { // not in a free range and/or should not coalesce |
| 8406 // Return the current free range and start a new one. | |
| 8407 if (inFreeRange()) { | |
| 8408 // In a free range but cannot coalesce with the right hand chunk. | |
| 8409 // Put the current free range into the free lists. | |
|
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|
8410 flush_cur_free_chunk(freeFinger(), |
|
3746
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|
8411 pointer_delta(fc_addr, freeFinger())); |
| 0 | 8412 } |
| 8413 // Set up for new free range. Pass along whether the right hand | |
| 8414 // chunk is in the free lists. | |
| 8415 initialize_free_range((HeapWord*)fc, fcInFreeLists); | |
| 8416 } | |
| 8417 } | |
|
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|
8418 |
|
3746
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|
8419 // Lookahead flush: |
|
537a4053b0f9
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|
8420 // If we are tracking a free range, and this is the last chunk that |
|
537a4053b0f9
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|
8421 // we'll look at because its end crosses past _limit, we'll preemptively |
|
537a4053b0f9
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|
8422 // flush it along with any free range we may be holding on to. Note that |
|
537a4053b0f9
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|
8423 // this can be the case only for an already free or freshly garbage |
|
537a4053b0f9
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|
8424 // chunk. If this block is an object, it can never straddle |
|
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|
8425 // over _limit. The "straddling" occurs when _limit is set at |
|
537a4053b0f9
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|
8426 // the previous end of the space when this cycle started, and |
|
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|
8427 // a subsequent heap expansion caused the previously co-terminal |
|
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|
8428 // free block to be coalesced with the newly expanded portion, |
|
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|
8429 // thus rendering _limit a non-block-boundary making it dangerous |
|
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|
8430 // for the sweeper to step over and examine. |
|
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|
8431 void SweepClosure::lookahead_and_flush(FreeChunk* fc, size_t chunk_size) { |
|
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|
8432 assert(inFreeRange(), "Should only be called if currently in a free range."); |
|
537a4053b0f9
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|
8433 HeapWord* const eob = ((HeapWord*)fc) + chunk_size; |
|
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|
8434 assert(_sp->used_region().contains(eob - 1), |
|
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|
8435 err_msg("eob = " PTR_FORMAT " out of bounds wrt _sp = [" PTR_FORMAT "," PTR_FORMAT ")" |
|
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|
8436 " when examining fc = " PTR_FORMAT "(" SIZE_FORMAT ")", |
|
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|
8437 _limit, _sp->bottom(), _sp->end(), fc, chunk_size)); |
|
537a4053b0f9
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|
8438 if (eob >= _limit) { |
|
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|
8439 assert(eob == _limit || fc->isFree(), "Only a free chunk should allow us to cross over the limit"); |
|
537a4053b0f9
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|
8440 if (CMSTraceSweeper) { |
|
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|
8441 gclog_or_tty->print_cr("_limit " PTR_FORMAT " reached or crossed by block " |
|
537a4053b0f9
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|
8442 "[" PTR_FORMAT "," PTR_FORMAT ") in space " |
|
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|
8443 "[" PTR_FORMAT "," PTR_FORMAT ")", |
|
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|
8444 _limit, fc, eob, _sp->bottom(), _sp->end()); |
|
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|
8445 } |
|
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|
8446 // Return the storage we are tracking back into the free lists. |
|
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|
8447 if (CMSTraceSweeper) { |
|
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|
8448 gclog_or_tty->print_cr("Flushing ... "); |
|
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|
8449 } |
|
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|
8450 assert(freeFinger() < eob, "Error"); |
|
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|
8451 flush_cur_free_chunk( freeFinger(), pointer_delta(eob, freeFinger())); |
|
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|
8452 } |
|
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|
8453 } |
|
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|
8454 |
|
2132
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|
8455 void SweepClosure::flush_cur_free_chunk(HeapWord* chunk, size_t size) { |
| 0 | 8456 assert(inFreeRange(), "Should only be called if currently in a free range."); |
| 8457 assert(size > 0, | |
| 8458 "A zero sized chunk cannot be added to the free lists."); | |
| 8459 if (!freeRangeInFreeLists()) { | |
|
2132
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|
8460 if (CMSTestInFreeList) { |
| 0 | 8461 FreeChunk* fc = (FreeChunk*) chunk; |
| 8462 fc->setSize(size); | |
| 8463 assert(!_sp->verifyChunkInFreeLists(fc), | |
| 8464 "chunk should not be in free lists yet"); | |
| 8465 } | |
| 8466 if (CMSTraceSweeper) { | |
| 8467 gclog_or_tty->print_cr(" -- add free block 0x%x (%d) to free lists", | |
| 8468 chunk, size); | |
| 8469 } | |
| 8470 // A new free range is going to be starting. The current | |
| 8471 // free range has not been added to the free lists yet or | |
| 8472 // was removed so add it back. | |
| 8473 // If the current free range was coalesced, then the death | |
| 8474 // of the free range was recorded. Record a birth now. | |
| 8475 if (lastFreeRangeCoalesced()) { | |
| 8476 _sp->coalBirth(size); | |
| 8477 } | |
| 8478 _sp->addChunkAndRepairOffsetTable(chunk, size, | |
| 8479 lastFreeRangeCoalesced()); | |
|
3746
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|
8480 } else if (CMSTraceSweeper) { |
|
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|
8481 gclog_or_tty->print_cr("Already in free list: nothing to flush"); |
| 0 | 8482 } |
| 8483 set_inFreeRange(false); | |
| 8484 set_freeRangeInFreeLists(false); | |
| 8485 } | |
| 8486 | |
| 8487 // We take a break if we've been at this for a while, | |
| 8488 // so as to avoid monopolizing the locks involved. | |
| 8489 void SweepClosure::do_yield_work(HeapWord* addr) { | |
| 8490 // Return current free chunk being used for coalescing (if any) | |
| 8491 // to the appropriate freelist. After yielding, the next | |
| 8492 // free block encountered will start a coalescing range of | |
| 8493 // free blocks. If the next free block is adjacent to the | |
| 8494 // chunk just flushed, they will need to wait for the next | |
| 8495 // sweep to be coalesced. | |
| 8496 if (inFreeRange()) { | |
|
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|
8497 flush_cur_free_chunk(freeFinger(), pointer_delta(addr, freeFinger())); |
| 0 | 8498 } |
| 8499 | |
| 8500 // First give up the locks, then yield, then re-lock. | |
| 8501 // We should probably use a constructor/destructor idiom to | |
| 8502 // do this unlock/lock or modify the MutexUnlocker class to | |
| 8503 // serve our purpose. XXX | |
| 8504 assert_lock_strong(_bitMap->lock()); | |
| 8505 assert_lock_strong(_freelistLock); | |
| 8506 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 8507 "CMS thread should hold CMS token"); | |
| 8508 _bitMap->lock()->unlock(); | |
| 8509 _freelistLock->unlock(); | |
| 8510 ConcurrentMarkSweepThread::desynchronize(true); | |
| 8511 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 8512 _collector->stopTimer(); | |
| 8513 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 8514 if (PrintCMSStatistics != 0) { | |
| 8515 _collector->incrementYields(); | |
| 8516 } | |
| 8517 _collector->icms_wait(); | |
| 8518 | |
| 8519 // See the comment in coordinator_yield() | |
| 8520 for (unsigned i = 0; i < CMSYieldSleepCount && | |
| 8521 ConcurrentMarkSweepThread::should_yield() && | |
| 8522 !CMSCollector::foregroundGCIsActive(); ++i) { | |
| 8523 os::sleep(Thread::current(), 1, false); | |
| 8524 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 8525 } | |
| 8526 | |
| 8527 ConcurrentMarkSweepThread::synchronize(true); | |
| 8528 _freelistLock->lock(); | |
| 8529 _bitMap->lock()->lock_without_safepoint_check(); | |
| 8530 _collector->startTimer(); | |
| 8531 } | |
| 8532 | |
| 8533 #ifndef PRODUCT | |
| 8534 // This is actually very useful in a product build if it can | |
| 8535 // be called from the debugger. Compile it into the product | |
| 8536 // as needed. | |
| 8537 bool debug_verifyChunkInFreeLists(FreeChunk* fc) { | |
| 8538 return debug_cms_space->verifyChunkInFreeLists(fc); | |
| 8539 } | |
|
3746
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|
8540 #endif |
|
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|
8541 |
|
537a4053b0f9
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|
8542 void SweepClosure::print_free_block_coalesced(FreeChunk* fc) const { |
| 0 | 8543 if (CMSTraceSweeper) { |
|
3746
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|
8544 gclog_or_tty->print_cr("Sweep:coal_free_blk " PTR_FORMAT " (" SIZE_FORMAT ")", |
|
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|
8545 fc, fc->size()); |
|
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|
8546 } |
|
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|
8547 } |
| 0 | 8548 |
| 8549 // CMSIsAliveClosure | |
| 8550 bool CMSIsAliveClosure::do_object_b(oop obj) { | |
| 8551 HeapWord* addr = (HeapWord*)obj; | |
| 8552 return addr != NULL && | |
| 8553 (!_span.contains(addr) || _bit_map->isMarked(addr)); | |
| 8554 } | |
| 8555 | |
| 935 | 8556 CMSKeepAliveClosure::CMSKeepAliveClosure( CMSCollector* collector, |
| 8557 MemRegion span, | |
| 8558 CMSBitMap* bit_map, CMSMarkStack* mark_stack, | |
| 8559 CMSMarkStack* revisit_stack, bool cpc): | |
| 8560 KlassRememberingOopClosure(collector, NULL, revisit_stack), | |
| 8561 _span(span), | |
| 8562 _bit_map(bit_map), | |
| 8563 _mark_stack(mark_stack), | |
| 8564 _concurrent_precleaning(cpc) { | |
| 8565 assert(!_span.is_empty(), "Empty span could spell trouble"); | |
| 8566 } | |
| 8567 | |
| 8568 | |
| 0 | 8569 // CMSKeepAliveClosure: the serial version |
|
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6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
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|
8570 void CMSKeepAliveClosure::do_oop(oop obj) { |
|
ba764ed4b6f2
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diff
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|
8571 HeapWord* addr = (HeapWord*)obj; |
| 0 | 8572 if (_span.contains(addr) && |
| 8573 !_bit_map->isMarked(addr)) { | |
| 8574 _bit_map->mark(addr); | |
| 8575 bool simulate_overflow = false; | |
| 8576 NOT_PRODUCT( | |
| 8577 if (CMSMarkStackOverflowALot && | |
| 8578 _collector->simulate_overflow()) { | |
| 8579 // simulate a stack overflow | |
| 8580 simulate_overflow = true; | |
| 8581 } | |
| 8582 ) | |
|
113
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|
8583 if (simulate_overflow || !_mark_stack->push(obj)) { |
|
452
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|
8584 if (_concurrent_precleaning) { |
|
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|
8585 // We dirty the overflown object and let the remark |
|
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|
8586 // phase deal with it. |
|
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|
8587 assert(_collector->overflow_list_is_empty(), "Error"); |
|
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|
8588 // In the case of object arrays, we need to dirty all of |
|
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|
8589 // the cards that the object spans. No locking or atomics |
|
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|
8590 // are needed since no one else can be mutating the mod union |
|
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|
8591 // table. |
|
00b023ae2d78
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|
8592 if (obj->is_objArray()) { |
|
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|
8593 size_t sz = obj->size(); |
|
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|
8594 HeapWord* end_card_addr = |
|
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|
8595 (HeapWord*)round_to((intptr_t)(addr+sz), CardTableModRefBS::card_size); |
|
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|
8596 MemRegion redirty_range = MemRegion(addr, end_card_addr); |
|
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|
8597 assert(!redirty_range.is_empty(), "Arithmetical tautology"); |
|
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|
8598 _collector->_modUnionTable.mark_range(redirty_range); |
|
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|
8599 } else { |
|
00b023ae2d78
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|
8600 _collector->_modUnionTable.mark(addr); |
|
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|
8601 } |
|
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|
8602 _collector->_ser_kac_preclean_ovflw++; |
|
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|
8603 } else { |
|
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8604 _collector->push_on_overflow_list(obj); |
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8605 _collector->_ser_kac_ovflw++; |
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8606 } |
| 0 | 8607 } |
| 8608 } | |
| 8609 } | |
| 8610 | |
|
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8611 void CMSKeepAliveClosure::do_oop(oop* p) { CMSKeepAliveClosure::do_oop_work(p); } |
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8612 void CMSKeepAliveClosure::do_oop(narrowOop* p) { CMSKeepAliveClosure::do_oop_work(p); } |
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8613 |
| 0 | 8614 // CMSParKeepAliveClosure: a parallel version of the above. |
| 8615 // The work queues are private to each closure (thread), | |
| 8616 // but (may be) available for stealing by other threads. | |
|
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8617 void CMSParKeepAliveClosure::do_oop(oop obj) { |
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8618 HeapWord* addr = (HeapWord*)obj; |
| 0 | 8619 if (_span.contains(addr) && |
| 8620 !_bit_map->isMarked(addr)) { | |
| 8621 // In general, during recursive tracing, several threads | |
| 8622 // may be concurrently getting here; the first one to | |
| 8623 // "tag" it, claims it. | |
| 8624 if (_bit_map->par_mark(addr)) { | |
|
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8625 bool res = _work_queue->push(obj); |
| 0 | 8626 assert(res, "Low water mark should be much less than capacity"); |
| 8627 // Do a recursive trim in the hope that this will keep | |
| 8628 // stack usage lower, but leave some oops for potential stealers | |
| 8629 trim_queue(_low_water_mark); | |
| 8630 } // Else, another thread got there first | |
| 8631 } | |
| 8632 } | |
| 8633 | |
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8634 void CMSParKeepAliveClosure::do_oop(oop* p) { CMSParKeepAliveClosure::do_oop_work(p); } |
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8635 void CMSParKeepAliveClosure::do_oop(narrowOop* p) { CMSParKeepAliveClosure::do_oop_work(p); } |
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8636 |
| 0 | 8637 void CMSParKeepAliveClosure::trim_queue(uint max) { |
| 8638 while (_work_queue->size() > max) { | |
| 8639 oop new_oop; | |
| 8640 if (_work_queue->pop_local(new_oop)) { | |
| 8641 assert(new_oop != NULL && new_oop->is_oop(), "Expected an oop"); | |
| 8642 assert(_bit_map->isMarked((HeapWord*)new_oop), | |
| 8643 "no white objects on this stack!"); | |
| 8644 assert(_span.contains((HeapWord*)new_oop), "Out of bounds oop"); | |
| 8645 // iterate over the oops in this oop, marking and pushing | |
| 8646 // the ones in CMS heap (i.e. in _span). | |
| 8647 new_oop->oop_iterate(&_mark_and_push); | |
| 8648 } | |
| 8649 } | |
| 8650 } | |
| 8651 | |
| 935 | 8652 CMSInnerParMarkAndPushClosure::CMSInnerParMarkAndPushClosure( |
| 8653 CMSCollector* collector, | |
| 8654 MemRegion span, CMSBitMap* bit_map, | |
| 8655 CMSMarkStack* revisit_stack, | |
| 8656 OopTaskQueue* work_queue): | |
| 8657 Par_KlassRememberingOopClosure(collector, NULL, revisit_stack), | |
| 8658 _span(span), | |
| 8659 _bit_map(bit_map), | |
| 8660 _work_queue(work_queue) { } | |
| 8661 | |
|
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8662 void CMSInnerParMarkAndPushClosure::do_oop(oop obj) { |
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8663 HeapWord* addr = (HeapWord*)obj; |
| 0 | 8664 if (_span.contains(addr) && |
| 8665 !_bit_map->isMarked(addr)) { | |
| 8666 if (_bit_map->par_mark(addr)) { | |
| 8667 bool simulate_overflow = false; | |
| 8668 NOT_PRODUCT( | |
| 8669 if (CMSMarkStackOverflowALot && | |
| 8670 _collector->par_simulate_overflow()) { | |
| 8671 // simulate a stack overflow | |
| 8672 simulate_overflow = true; | |
| 8673 } | |
| 8674 ) | |
|
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8675 if (simulate_overflow || !_work_queue->push(obj)) { |
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8676 _collector->par_push_on_overflow_list(obj); |
| 0 | 8677 _collector->_par_kac_ovflw++; |
| 8678 } | |
| 8679 } // Else another thread got there already | |
| 8680 } | |
| 8681 } | |
| 8682 | |
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8683 void CMSInnerParMarkAndPushClosure::do_oop(oop* p) { CMSInnerParMarkAndPushClosure::do_oop_work(p); } |
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8684 void CMSInnerParMarkAndPushClosure::do_oop(narrowOop* p) { CMSInnerParMarkAndPushClosure::do_oop_work(p); } |
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8685 |
| 0 | 8686 ////////////////////////////////////////////////////////////////// |
| 8687 // CMSExpansionCause ///////////////////////////// | |
| 8688 ////////////////////////////////////////////////////////////////// | |
| 8689 const char* CMSExpansionCause::to_string(CMSExpansionCause::Cause cause) { | |
| 8690 switch (cause) { | |
| 8691 case _no_expansion: | |
| 8692 return "No expansion"; | |
| 8693 case _satisfy_free_ratio: | |
| 8694 return "Free ratio"; | |
| 8695 case _satisfy_promotion: | |
| 8696 return "Satisfy promotion"; | |
| 8697 case _satisfy_allocation: | |
| 8698 return "allocation"; | |
| 8699 case _allocate_par_lab: | |
| 8700 return "Par LAB"; | |
| 8701 case _allocate_par_spooling_space: | |
| 8702 return "Par Spooling Space"; | |
| 8703 case _adaptive_size_policy: | |
| 8704 return "Ergonomics"; | |
| 8705 default: | |
| 8706 return "unknown"; | |
| 8707 } | |
| 8708 } | |
| 8709 | |
| 8710 void CMSDrainMarkingStackClosure::do_void() { | |
| 8711 // the max number to take from overflow list at a time | |
| 8712 const size_t num = _mark_stack->capacity()/4; | |
|
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8713 assert(!_concurrent_precleaning || _collector->overflow_list_is_empty(), |
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8714 "Overflow list should be NULL during concurrent phases"); |
| 0 | 8715 while (!_mark_stack->isEmpty() || |
| 8716 // if stack is empty, check the overflow list | |
| 8717 _collector->take_from_overflow_list(num, _mark_stack)) { | |
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8718 oop obj = _mark_stack->pop(); |
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8719 HeapWord* addr = (HeapWord*)obj; |
| 0 | 8720 assert(_span.contains(addr), "Should be within span"); |
| 8721 assert(_bit_map->isMarked(addr), "Should be marked"); | |
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8722 assert(obj->is_oop(), "Should be an oop"); |
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8723 obj->oop_iterate(_keep_alive); |
| 0 | 8724 } |
| 8725 } | |
| 8726 | |
| 8727 void CMSParDrainMarkingStackClosure::do_void() { | |
| 8728 // drain queue | |
| 8729 trim_queue(0); | |
| 8730 } | |
| 8731 | |
| 8732 // Trim our work_queue so its length is below max at return | |
| 8733 void CMSParDrainMarkingStackClosure::trim_queue(uint max) { | |
| 8734 while (_work_queue->size() > max) { | |
| 8735 oop new_oop; | |
| 8736 if (_work_queue->pop_local(new_oop)) { | |
| 8737 assert(new_oop->is_oop(), "Expected an oop"); | |
| 8738 assert(_bit_map->isMarked((HeapWord*)new_oop), | |
| 8739 "no white objects on this stack!"); | |
| 8740 assert(_span.contains((HeapWord*)new_oop), "Out of bounds oop"); | |
| 8741 // iterate over the oops in this oop, marking and pushing | |
| 8742 // the ones in CMS heap (i.e. in _span). | |
| 8743 new_oop->oop_iterate(&_mark_and_push); | |
| 8744 } | |
| 8745 } | |
| 8746 } | |
| 8747 | |
| 8748 //////////////////////////////////////////////////////////////////// | |
| 8749 // Support for Marking Stack Overflow list handling and related code | |
| 8750 //////////////////////////////////////////////////////////////////// | |
| 8751 // Much of the following code is similar in shape and spirit to the | |
| 8752 // code used in ParNewGC. We should try and share that code | |
| 8753 // as much as possible in the future. | |
| 8754 | |
| 8755 #ifndef PRODUCT | |
| 8756 // Debugging support for CMSStackOverflowALot | |
| 8757 | |
| 8758 // It's OK to call this multi-threaded; the worst thing | |
| 8759 // that can happen is that we'll get a bunch of closely | |
| 8760 // spaced simulated oveflows, but that's OK, in fact | |
| 8761 // probably good as it would exercise the overflow code | |
| 8762 // under contention. | |
| 8763 bool CMSCollector::simulate_overflow() { | |
| 8764 if (_overflow_counter-- <= 0) { // just being defensive | |
| 8765 _overflow_counter = CMSMarkStackOverflowInterval; | |
| 8766 return true; | |
| 8767 } else { | |
| 8768 return false; | |
| 8769 } | |
| 8770 } | |
| 8771 | |
| 8772 bool CMSCollector::par_simulate_overflow() { | |
| 8773 return simulate_overflow(); | |
| 8774 } | |
| 8775 #endif | |
| 8776 | |
| 8777 // Single-threaded | |
| 8778 bool CMSCollector::take_from_overflow_list(size_t num, CMSMarkStack* stack) { | |
| 8779 assert(stack->isEmpty(), "Expected precondition"); | |
| 8780 assert(stack->capacity() > num, "Shouldn't bite more than can chew"); | |
| 8781 size_t i = num; | |
| 8782 oop cur = _overflow_list; | |
| 8783 const markOop proto = markOopDesc::prototype(); | |
| 534 | 8784 NOT_PRODUCT(ssize_t n = 0;) |
| 0 | 8785 for (oop next; i > 0 && cur != NULL; cur = next, i--) { |
| 8786 next = oop(cur->mark()); | |
| 8787 cur->set_mark(proto); // until proven otherwise | |
| 8788 assert(cur->is_oop(), "Should be an oop"); | |
| 8789 bool res = stack->push(cur); | |
| 8790 assert(res, "Bit off more than can chew?"); | |
| 8791 NOT_PRODUCT(n++;) | |
| 8792 } | |
| 8793 _overflow_list = cur; | |
| 8794 #ifndef PRODUCT | |
| 8795 assert(_num_par_pushes >= n, "Too many pops?"); | |
| 8796 _num_par_pushes -=n; | |
| 8797 #endif | |
| 8798 return !stack->isEmpty(); | |
| 8799 } | |
| 8800 | |
| 534 | 8801 #define BUSY (oop(0x1aff1aff)) |
| 8802 // (MT-safe) Get a prefix of at most "num" from the list. | |
| 8803 // The overflow list is chained through the mark word of | |
| 8804 // each object in the list. We fetch the entire list, | |
| 8805 // break off a prefix of the right size and return the | |
| 8806 // remainder. If other threads try to take objects from | |
| 8807 // the overflow list at that time, they will wait for | |
| 8808 // some time to see if data becomes available. If (and | |
| 8809 // only if) another thread places one or more object(s) | |
| 8810 // on the global list before we have returned the suffix | |
| 8811 // to the global list, we will walk down our local list | |
| 8812 // to find its end and append the global list to | |
| 8813 // our suffix before returning it. This suffix walk can | |
| 8814 // prove to be expensive (quadratic in the amount of traffic) | |
| 8815 // when there are many objects in the overflow list and | |
| 8816 // there is much producer-consumer contention on the list. | |
| 8817 // *NOTE*: The overflow list manipulation code here and | |
| 8818 // in ParNewGeneration:: are very similar in shape, | |
| 8819 // except that in the ParNew case we use the old (from/eden) | |
| 8820 // copy of the object to thread the list via its klass word. | |
| 8821 // Because of the common code, if you make any changes in | |
| 8822 // the code below, please check the ParNew version to see if | |
| 8823 // similar changes might be needed. | |
| 8824 // CR 6797058 has been filed to consolidate the common code. | |
| 0 | 8825 bool CMSCollector::par_take_from_overflow_list(size_t num, |
|
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8826 OopTaskQueue* work_q, |
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8827 int no_of_gc_threads) { |
| 534 | 8828 assert(work_q->size() == 0, "First empty local work queue"); |
| 0 | 8829 assert(num < work_q->max_elems(), "Can't bite more than we can chew"); |
| 8830 if (_overflow_list == NULL) { | |
| 8831 return false; | |
| 8832 } | |
| 8833 // Grab the entire list; we'll put back a suffix | |
| 534 | 8834 oop prefix = (oop)Atomic::xchg_ptr(BUSY, &_overflow_list); |
| 8835 Thread* tid = Thread::current(); | |
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8836 // Before "no_of_gc_threads" was introduced CMSOverflowSpinCount was |
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8837 // set to ParallelGCThreads. |
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8838 size_t CMSOverflowSpinCount = (size_t) no_of_gc_threads; // was ParallelGCThreads; |
| 534 | 8839 size_t sleep_time_millis = MAX2((size_t)1, num/100); |
| 8840 // If the list is busy, we spin for a short while, | |
| 8841 // sleeping between attempts to get the list. | |
| 8842 for (size_t spin = 0; prefix == BUSY && spin < CMSOverflowSpinCount; spin++) { | |
| 8843 os::sleep(tid, sleep_time_millis, false); | |
| 8844 if (_overflow_list == NULL) { | |
| 8845 // Nothing left to take | |
| 8846 return false; | |
| 8847 } else if (_overflow_list != BUSY) { | |
| 8848 // Try and grab the prefix | |
| 8849 prefix = (oop)Atomic::xchg_ptr(BUSY, &_overflow_list); | |
| 8850 } | |
| 8851 } | |
| 8852 // If the list was found to be empty, or we spun long | |
| 8853 // enough, we give up and return empty-handed. If we leave | |
| 8854 // the list in the BUSY state below, it must be the case that | |
| 8855 // some other thread holds the overflow list and will set it | |
| 8856 // to a non-BUSY state in the future. | |
| 8857 if (prefix == NULL || prefix == BUSY) { | |
| 8858 // Nothing to take or waited long enough | |
| 8859 if (prefix == NULL) { | |
| 8860 // Write back the NULL in case we overwrote it with BUSY above | |
| 8861 // and it is still the same value. | |
| 8862 (void) Atomic::cmpxchg_ptr(NULL, &_overflow_list, BUSY); | |
| 8863 } | |
| 8864 return false; | |
| 8865 } | |
| 8866 assert(prefix != NULL && prefix != BUSY, "Error"); | |
| 0 | 8867 size_t i = num; |
| 8868 oop cur = prefix; | |
| 534 | 8869 // Walk down the first "num" objects, unless we reach the end. |
| 0 | 8870 for (; i > 1 && cur->mark() != NULL; cur = oop(cur->mark()), i--); |
| 534 | 8871 if (cur->mark() == NULL) { |
| 8872 // We have "num" or fewer elements in the list, so there | |
| 8873 // is nothing to return to the global list. | |
| 8874 // Write back the NULL in lieu of the BUSY we wrote | |
| 8875 // above, if it is still the same value. | |
| 8876 if (_overflow_list == BUSY) { | |
| 8877 (void) Atomic::cmpxchg_ptr(NULL, &_overflow_list, BUSY); | |
| 8878 } | |
| 8879 } else { | |
| 8880 // Chop off the suffix and rerturn it to the global list. | |
| 8881 assert(cur->mark() != BUSY, "Error"); | |
| 0 | 8882 oop suffix_head = cur->mark(); // suffix will be put back on global list |
| 8883 cur->set_mark(NULL); // break off suffix | |
| 534 | 8884 // It's possible that the list is still in the empty(busy) state |
| 8885 // we left it in a short while ago; in that case we may be | |
| 8886 // able to place back the suffix without incurring the cost | |
| 8887 // of a walk down the list. | |
| 0 | 8888 oop observed_overflow_list = _overflow_list; |
| 534 | 8889 oop cur_overflow_list = observed_overflow_list; |
| 8890 bool attached = false; | |
| 8891 while (observed_overflow_list == BUSY || observed_overflow_list == NULL) { | |
| 0 | 8892 observed_overflow_list = |
| 534 | 8893 (oop) Atomic::cmpxchg_ptr(suffix_head, &_overflow_list, cur_overflow_list); |
| 8894 if (cur_overflow_list == observed_overflow_list) { | |
| 8895 attached = true; | |
| 8896 break; | |
| 8897 } else cur_overflow_list = observed_overflow_list; | |
| 8898 } | |
| 8899 if (!attached) { | |
| 8900 // Too bad, someone else sneaked in (at least) an element; we'll need | |
| 8901 // to do a splice. Find tail of suffix so we can prepend suffix to global | |
| 8902 // list. | |
| 8903 for (cur = suffix_head; cur->mark() != NULL; cur = (oop)(cur->mark())); | |
| 8904 oop suffix_tail = cur; | |
| 8905 assert(suffix_tail != NULL && suffix_tail->mark() == NULL, | |
| 8906 "Tautology"); | |
| 8907 observed_overflow_list = _overflow_list; | |
| 8908 do { | |
| 8909 cur_overflow_list = observed_overflow_list; | |
| 8910 if (cur_overflow_list != BUSY) { | |
| 8911 // Do the splice ... | |
| 8912 suffix_tail->set_mark(markOop(cur_overflow_list)); | |
| 8913 } else { // cur_overflow_list == BUSY | |
| 8914 suffix_tail->set_mark(NULL); | |
| 8915 } | |
| 8916 // ... and try to place spliced list back on overflow_list ... | |
| 8917 observed_overflow_list = | |
| 8918 (oop) Atomic::cmpxchg_ptr(suffix_head, &_overflow_list, cur_overflow_list); | |
| 8919 } while (cur_overflow_list != observed_overflow_list); | |
| 8920 // ... until we have succeeded in doing so. | |
| 8921 } | |
| 0 | 8922 } |
| 8923 | |
| 8924 // Push the prefix elements on work_q | |
| 8925 assert(prefix != NULL, "control point invariant"); | |
| 8926 const markOop proto = markOopDesc::prototype(); | |
| 8927 oop next; | |
| 534 | 8928 NOT_PRODUCT(ssize_t n = 0;) |
| 0 | 8929 for (cur = prefix; cur != NULL; cur = next) { |
| 8930 next = oop(cur->mark()); | |
| 8931 cur->set_mark(proto); // until proven otherwise | |
| 8932 assert(cur->is_oop(), "Should be an oop"); | |
| 8933 bool res = work_q->push(cur); | |
| 8934 assert(res, "Bit off more than we can chew?"); | |
| 8935 NOT_PRODUCT(n++;) | |
| 8936 } | |
| 8937 #ifndef PRODUCT | |
| 8938 assert(_num_par_pushes >= n, "Too many pops?"); | |
| 8939 Atomic::add_ptr(-(intptr_t)n, &_num_par_pushes); | |
| 8940 #endif | |
| 8941 return true; | |
| 8942 } | |
| 8943 | |
| 8944 // Single-threaded | |
| 8945 void CMSCollector::push_on_overflow_list(oop p) { | |
| 8946 NOT_PRODUCT(_num_par_pushes++;) | |
| 8947 assert(p->is_oop(), "Not an oop"); | |
| 8948 preserve_mark_if_necessary(p); | |
| 8949 p->set_mark((markOop)_overflow_list); | |
| 8950 _overflow_list = p; | |
| 8951 } | |
| 8952 | |
| 8953 // Multi-threaded; use CAS to prepend to overflow list | |
| 8954 void CMSCollector::par_push_on_overflow_list(oop p) { | |
| 8955 NOT_PRODUCT(Atomic::inc_ptr(&_num_par_pushes);) | |
| 8956 assert(p->is_oop(), "Not an oop"); | |
| 8957 par_preserve_mark_if_necessary(p); | |
| 8958 oop observed_overflow_list = _overflow_list; | |
| 8959 oop cur_overflow_list; | |
| 8960 do { | |
| 8961 cur_overflow_list = observed_overflow_list; | |
| 534 | 8962 if (cur_overflow_list != BUSY) { |
| 8963 p->set_mark(markOop(cur_overflow_list)); | |
| 8964 } else { | |
| 8965 p->set_mark(NULL); | |
| 8966 } | |
| 0 | 8967 observed_overflow_list = |
| 8968 (oop) Atomic::cmpxchg_ptr(p, &_overflow_list, cur_overflow_list); | |
| 8969 } while (cur_overflow_list != observed_overflow_list); | |
| 8970 } | |
| 534 | 8971 #undef BUSY |
| 0 | 8972 |
| 8973 // Single threaded | |
| 8974 // General Note on GrowableArray: pushes may silently fail | |
| 8975 // because we are (temporarily) out of C-heap for expanding | |
| 8976 // the stack. The problem is quite ubiquitous and affects | |
| 8977 // a lot of code in the JVM. The prudent thing for GrowableArray | |
| 8978 // to do (for now) is to exit with an error. However, that may | |
| 8979 // be too draconian in some cases because the caller may be | |
| 534 | 8980 // able to recover without much harm. For such cases, we |
| 0 | 8981 // should probably introduce a "soft_push" method which returns |
| 8982 // an indication of success or failure with the assumption that | |
| 8983 // the caller may be able to recover from a failure; code in | |
| 8984 // the VM can then be changed, incrementally, to deal with such | |
| 8985 // failures where possible, thus, incrementally hardening the VM | |
| 8986 // in such low resource situations. | |
| 8987 void CMSCollector::preserve_mark_work(oop p, markOop m) { | |
|
1836
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6423256: GC stacks should use a better data structure
jcoomes
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1833
diff
changeset
|
8988 _preserved_oop_stack.push(p); |
|
894b1d7c7e01
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jcoomes
parents:
1833
diff
changeset
|
8989 _preserved_mark_stack.push(m); |
| 0 | 8990 assert(m == p->mark(), "Mark word changed"); |
|
1836
894b1d7c7e01
6423256: GC stacks should use a better data structure
jcoomes
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1833
diff
changeset
|
8991 assert(_preserved_oop_stack.size() == _preserved_mark_stack.size(), |
| 0 | 8992 "bijection"); |
| 8993 } | |
| 8994 | |
| 8995 // Single threaded | |
| 8996 void CMSCollector::preserve_mark_if_necessary(oop p) { | |
| 8997 markOop m = p->mark(); | |
| 8998 if (m->must_be_preserved(p)) { | |
| 8999 preserve_mark_work(p, m); | |
| 9000 } | |
| 9001 } | |
| 9002 | |
| 9003 void CMSCollector::par_preserve_mark_if_necessary(oop p) { | |
| 9004 markOop m = p->mark(); | |
| 9005 if (m->must_be_preserved(p)) { | |
| 9006 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); | |
| 9007 // Even though we read the mark word without holding | |
| 9008 // the lock, we are assured that it will not change | |
| 9009 // because we "own" this oop, so no other thread can | |
| 9010 // be trying to push it on the overflow list; see | |
| 9011 // the assertion in preserve_mark_work() that checks | |
| 9012 // that m == p->mark(). | |
| 9013 preserve_mark_work(p, m); | |
| 9014 } | |
| 9015 } | |
| 9016 | |
| 9017 // We should be able to do this multi-threaded, | |
| 9018 // a chunk of stack being a task (this is | |
| 9019 // correct because each oop only ever appears | |
| 9020 // once in the overflow list. However, it's | |
| 9021 // not very easy to completely overlap this with | |
| 9022 // other operations, so will generally not be done | |
| 9023 // until all work's been completed. Because we | |
| 9024 // expect the preserved oop stack (set) to be small, | |
| 9025 // it's probably fine to do this single-threaded. | |
| 9026 // We can explore cleverer concurrent/overlapped/parallel | |
| 9027 // processing of preserved marks if we feel the | |
| 9028 // need for this in the future. Stack overflow should | |
| 9029 // be so rare in practice and, when it happens, its | |
| 9030 // effect on performance so great that this will | |
| 9031 // likely just be in the noise anyway. | |
| 9032 void CMSCollector::restore_preserved_marks_if_any() { | |
| 9033 assert(SafepointSynchronize::is_at_safepoint(), | |
| 9034 "world should be stopped"); | |
| 9035 assert(Thread::current()->is_ConcurrentGC_thread() || | |
| 9036 Thread::current()->is_VM_thread(), | |
| 9037 "should be single-threaded"); | |
|
1836
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diff
changeset
|
9038 assert(_preserved_oop_stack.size() == _preserved_mark_stack.size(), |
|
894b1d7c7e01
6423256: GC stacks should use a better data structure
jcoomes
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1833
diff
changeset
|
9039 "bijection"); |
|
894b1d7c7e01
6423256: GC stacks should use a better data structure
jcoomes
parents:
1833
diff
changeset
|
9040 |
|
894b1d7c7e01
6423256: GC stacks should use a better data structure
jcoomes
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diff
changeset
|
9041 while (!_preserved_oop_stack.is_empty()) { |
|
894b1d7c7e01
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jcoomes
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1833
diff
changeset
|
9042 oop p = _preserved_oop_stack.pop(); |
| 0 | 9043 assert(p->is_oop(), "Should be an oop"); |
| 9044 assert(_span.contains(p), "oop should be in _span"); | |
| 9045 assert(p->mark() == markOopDesc::prototype(), | |
| 9046 "Set when taken from overflow list"); | |
|
1836
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jcoomes
parents:
1833
diff
changeset
|
9047 markOop m = _preserved_mark_stack.pop(); |
| 0 | 9048 p->set_mark(m); |
| 9049 } | |
|
1836
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1833
diff
changeset
|
9050 assert(_preserved_mark_stack.is_empty() && _preserved_oop_stack.is_empty(), |
| 0 | 9051 "stacks were cleared above"); |
| 9052 } | |
| 9053 | |
| 9054 #ifndef PRODUCT | |
| 9055 bool CMSCollector::no_preserved_marks() const { | |
|
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diff
changeset
|
9056 return _preserved_mark_stack.is_empty() && _preserved_oop_stack.is_empty(); |
| 0 | 9057 } |
| 9058 #endif | |
| 9059 | |
| 9060 CMSAdaptiveSizePolicy* ASConcurrentMarkSweepGeneration::cms_size_policy() const | |
| 9061 { | |
| 9062 GenCollectedHeap* gch = (GenCollectedHeap*) GenCollectedHeap::heap(); | |
| 9063 CMSAdaptiveSizePolicy* size_policy = | |
| 9064 (CMSAdaptiveSizePolicy*) gch->gen_policy()->size_policy(); | |
| 9065 assert(size_policy->is_gc_cms_adaptive_size_policy(), | |
| 9066 "Wrong type for size policy"); | |
| 9067 return size_policy; | |
| 9068 } | |
| 9069 | |
| 9070 void ASConcurrentMarkSweepGeneration::resize(size_t cur_promo_size, | |
| 9071 size_t desired_promo_size) { | |
| 9072 if (cur_promo_size < desired_promo_size) { | |
| 9073 size_t expand_bytes = desired_promo_size - cur_promo_size; | |
| 9074 if (PrintAdaptiveSizePolicy && Verbose) { | |
| 9075 gclog_or_tty->print_cr(" ASConcurrentMarkSweepGeneration::resize " | |
| 9076 "Expanding tenured generation by " SIZE_FORMAT " (bytes)", | |
| 9077 expand_bytes); | |
| 9078 } | |
| 9079 expand(expand_bytes, | |
| 9080 MinHeapDeltaBytes, | |
| 9081 CMSExpansionCause::_adaptive_size_policy); | |
| 9082 } else if (desired_promo_size < cur_promo_size) { | |
| 9083 size_t shrink_bytes = cur_promo_size - desired_promo_size; | |
| 9084 if (PrintAdaptiveSizePolicy && Verbose) { | |
| 9085 gclog_or_tty->print_cr(" ASConcurrentMarkSweepGeneration::resize " | |
| 9086 "Shrinking tenured generation by " SIZE_FORMAT " (bytes)", | |
| 9087 shrink_bytes); | |
| 9088 } | |
| 9089 shrink(shrink_bytes); | |
| 9090 } | |
| 9091 } | |
| 9092 | |
| 9093 CMSGCAdaptivePolicyCounters* ASConcurrentMarkSweepGeneration::gc_adaptive_policy_counters() { | |
| 9094 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 9095 CMSGCAdaptivePolicyCounters* counters = | |
| 9096 (CMSGCAdaptivePolicyCounters*) gch->collector_policy()->counters(); | |
| 9097 assert(counters->kind() == GCPolicyCounters::CMSGCAdaptivePolicyCountersKind, | |
| 9098 "Wrong kind of counters"); | |
| 9099 return counters; | |
| 9100 } | |
| 9101 | |
| 9102 | |
| 9103 void ASConcurrentMarkSweepGeneration::update_counters() { | |
| 9104 if (UsePerfData) { | |
| 9105 _space_counters->update_all(); | |
| 9106 _gen_counters->update_all(); | |
| 9107 CMSGCAdaptivePolicyCounters* counters = gc_adaptive_policy_counters(); | |
| 9108 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 9109 CMSGCStats* gc_stats_l = (CMSGCStats*) gc_stats(); | |
| 9110 assert(gc_stats_l->kind() == GCStats::CMSGCStatsKind, | |
| 9111 "Wrong gc statistics type"); | |
| 9112 counters->update_counters(gc_stats_l); | |
| 9113 } | |
| 9114 } | |
| 9115 | |
| 9116 void ASConcurrentMarkSweepGeneration::update_counters(size_t used) { | |
| 9117 if (UsePerfData) { | |
| 9118 _space_counters->update_used(used); | |
| 9119 _space_counters->update_capacity(); | |
| 9120 _gen_counters->update_all(); | |
| 9121 | |
| 9122 CMSGCAdaptivePolicyCounters* counters = gc_adaptive_policy_counters(); | |
| 9123 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 9124 CMSGCStats* gc_stats_l = (CMSGCStats*) gc_stats(); | |
| 9125 assert(gc_stats_l->kind() == GCStats::CMSGCStatsKind, | |
| 9126 "Wrong gc statistics type"); | |
| 9127 counters->update_counters(gc_stats_l); | |
| 9128 } | |
| 9129 } | |
| 9130 | |
| 9131 // The desired expansion delta is computed so that: | |
| 9132 // . desired free percentage or greater is used | |
| 9133 void ASConcurrentMarkSweepGeneration::compute_new_size() { | |
| 9134 assert_locked_or_safepoint(Heap_lock); | |
| 9135 | |
| 9136 GenCollectedHeap* gch = (GenCollectedHeap*) GenCollectedHeap::heap(); | |
| 9137 | |
| 9138 // If incremental collection failed, we just want to expand | |
| 9139 // to the limit. | |
| 9140 if (incremental_collection_failed()) { | |
| 9141 clear_incremental_collection_failed(); | |
| 9142 grow_to_reserved(); | |
| 9143 return; | |
| 9144 } | |
| 9145 | |
| 9146 assert(UseAdaptiveSizePolicy, "Should be using adaptive sizing"); | |
| 9147 | |
| 9148 assert(gch->kind() == CollectedHeap::GenCollectedHeap, | |
| 9149 "Wrong type of heap"); | |
| 9150 int prev_level = level() - 1; | |
| 9151 assert(prev_level >= 0, "The cms generation is the lowest generation"); | |
| 9152 Generation* prev_gen = gch->get_gen(prev_level); | |
| 9153 assert(prev_gen->kind() == Generation::ASParNew, | |
| 9154 "Wrong type of young generation"); | |
| 9155 ParNewGeneration* younger_gen = (ParNewGeneration*) prev_gen; | |
| 9156 size_t cur_eden = younger_gen->eden()->capacity(); | |
| 9157 CMSAdaptiveSizePolicy* size_policy = cms_size_policy(); | |
| 9158 size_t cur_promo = free(); | |
| 9159 size_policy->compute_tenured_generation_free_space(cur_promo, | |
| 9160 max_available(), | |
| 9161 cur_eden); | |
| 9162 resize(cur_promo, size_policy->promo_size()); | |
| 9163 | |
| 9164 // Record the new size of the space in the cms generation | |
| 9165 // that is available for promotions. This is temporary. | |
| 9166 // It should be the desired promo size. | |
| 9167 size_policy->avg_cms_promo()->sample(free()); | |
| 9168 size_policy->avg_old_live()->sample(used()); | |
| 9169 | |
| 9170 if (UsePerfData) { | |
| 9171 CMSGCAdaptivePolicyCounters* counters = gc_adaptive_policy_counters(); | |
| 9172 counters->update_cms_capacity_counter(capacity()); | |
| 9173 } | |
| 9174 } | |
| 9175 | |
| 9176 void ASConcurrentMarkSweepGeneration::shrink_by(size_t desired_bytes) { | |
| 9177 assert_locked_or_safepoint(Heap_lock); | |
| 9178 assert_lock_strong(freelistLock()); | |
| 9179 HeapWord* old_end = _cmsSpace->end(); | |
| 9180 HeapWord* unallocated_start = _cmsSpace->unallocated_block(); | |
| 9181 assert(old_end >= unallocated_start, "Miscalculation of unallocated_start"); | |
| 9182 FreeChunk* chunk_at_end = find_chunk_at_end(); | |
| 9183 if (chunk_at_end == NULL) { | |
| 9184 // No room to shrink | |
| 9185 if (PrintGCDetails && Verbose) { | |
| 9186 gclog_or_tty->print_cr("No room to shrink: old_end " | |
| 9187 PTR_FORMAT " unallocated_start " PTR_FORMAT | |
| 9188 " chunk_at_end " PTR_FORMAT, | |
| 9189 old_end, unallocated_start, chunk_at_end); | |
| 9190 } | |
| 9191 return; | |
| 9192 } else { | |
| 9193 | |
| 9194 // Find the chunk at the end of the space and determine | |
| 9195 // how much it can be shrunk. | |
| 9196 size_t shrinkable_size_in_bytes = chunk_at_end->size(); | |
| 9197 size_t aligned_shrinkable_size_in_bytes = | |
| 9198 align_size_down(shrinkable_size_in_bytes, os::vm_page_size()); | |
| 9199 assert(unallocated_start <= chunk_at_end->end(), | |
| 9200 "Inconsistent chunk at end of space"); | |
| 9201 size_t bytes = MIN2(desired_bytes, aligned_shrinkable_size_in_bytes); | |
| 9202 size_t word_size_before = heap_word_size(_virtual_space.committed_size()); | |
| 9203 | |
| 9204 // Shrink the underlying space | |
| 9205 _virtual_space.shrink_by(bytes); | |
| 9206 if (PrintGCDetails && Verbose) { | |
| 9207 gclog_or_tty->print_cr("ConcurrentMarkSweepGeneration::shrink_by:" | |
| 9208 " desired_bytes " SIZE_FORMAT | |
| 9209 " shrinkable_size_in_bytes " SIZE_FORMAT | |
| 9210 " aligned_shrinkable_size_in_bytes " SIZE_FORMAT | |
| 9211 " bytes " SIZE_FORMAT, | |
| 9212 desired_bytes, shrinkable_size_in_bytes, | |
| 9213 aligned_shrinkable_size_in_bytes, bytes); | |
| 9214 gclog_or_tty->print_cr(" old_end " SIZE_FORMAT | |
| 9215 " unallocated_start " SIZE_FORMAT, | |
| 9216 old_end, unallocated_start); | |
| 9217 } | |
| 9218 | |
| 9219 // If the space did shrink (shrinking is not guaranteed), | |
| 9220 // shrink the chunk at the end by the appropriate amount. | |
| 9221 if (((HeapWord*)_virtual_space.high()) < old_end) { | |
| 9222 size_t new_word_size = | |
| 9223 heap_word_size(_virtual_space.committed_size()); | |
| 9224 | |
| 9225 // Have to remove the chunk from the dictionary because it is changing | |
| 9226 // size and might be someplace elsewhere in the dictionary. | |
| 9227 | |
| 9228 // Get the chunk at end, shrink it, and put it | |
| 9229 // back. | |
| 9230 _cmsSpace->removeChunkFromDictionary(chunk_at_end); | |
| 9231 size_t word_size_change = word_size_before - new_word_size; | |
| 9232 size_t chunk_at_end_old_size = chunk_at_end->size(); | |
| 9233 assert(chunk_at_end_old_size >= word_size_change, | |
| 9234 "Shrink is too large"); | |
| 9235 chunk_at_end->setSize(chunk_at_end_old_size - | |
| 9236 word_size_change); | |
| 9237 _cmsSpace->freed((HeapWord*) chunk_at_end->end(), | |
| 9238 word_size_change); | |
| 9239 | |
| 9240 _cmsSpace->returnChunkToDictionary(chunk_at_end); | |
| 9241 | |
| 9242 MemRegion mr(_cmsSpace->bottom(), new_word_size); | |
| 9243 _bts->resize(new_word_size); // resize the block offset shared array | |
| 9244 Universe::heap()->barrier_set()->resize_covered_region(mr); | |
| 9245 _cmsSpace->assert_locked(); | |
| 9246 _cmsSpace->set_end((HeapWord*)_virtual_space.high()); | |
| 9247 | |
| 9248 NOT_PRODUCT(_cmsSpace->dictionary()->verify()); | |
| 9249 | |
| 9250 // update the space and generation capacity counters | |
| 9251 if (UsePerfData) { | |
| 9252 _space_counters->update_capacity(); | |
| 9253 _gen_counters->update_all(); | |
| 9254 } | |
| 9255 | |
| 9256 if (Verbose && PrintGCDetails) { | |
| 9257 size_t new_mem_size = _virtual_space.committed_size(); | |
| 9258 size_t old_mem_size = new_mem_size + bytes; | |
| 9259 gclog_or_tty->print_cr("Shrinking %s from %ldK by %ldK to %ldK", | |
| 9260 name(), old_mem_size/K, bytes/K, new_mem_size/K); | |
| 9261 } | |
| 9262 } | |
| 9263 | |
| 9264 assert(_cmsSpace->unallocated_block() <= _cmsSpace->end(), | |
| 9265 "Inconsistency at end of space"); | |
| 9266 assert(chunk_at_end->end() == _cmsSpace->end(), | |
| 9267 "Shrinking is inconsistent"); | |
| 9268 return; | |
| 9269 } | |
| 9270 } | |
| 9271 | |
| 9272 // Transfer some number of overflown objects to usual marking | |
| 9273 // stack. Return true if some objects were transferred. | |
| 9274 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
|
9275 size_t num = MIN2((size_t)(_mark_stack->capacity() - _mark_stack->length())/4, |
| 0 | 9276 (size_t)ParGCDesiredObjsFromOverflowList); |
| 9277 | |
| 9278 bool res = _collector->take_from_overflow_list(num, _mark_stack); | |
| 9279 assert(_collector->overflow_list_is_empty() || res, | |
| 9280 "If list is not empty, we should have taken something"); | |
| 9281 assert(!res || !_mark_stack->isEmpty(), | |
| 9282 "If we took something, it should now be on our stack"); | |
| 9283 return res; | |
| 9284 } | |
| 9285 | |
| 9286 size_t MarkDeadObjectsClosure::do_blk(HeapWord* addr) { | |
| 9287 size_t res = _sp->block_size_no_stall(addr, _collector); | |
| 9288 if (_sp->block_is_obj(addr)) { | |
| 9289 if (_live_bit_map->isMarked(addr)) { | |
| 9290 // It can't have been dead in a previous cycle | |
| 9291 guarantee(!_dead_bit_map->isMarked(addr), "No resurrection!"); | |
| 9292 } else { | |
| 9293 _dead_bit_map->mark(addr); // mark the dead object | |
| 9294 } | |
| 9295 } | |
|
2226
c5a923563727
6912621: iCMS: Error: assert(_markBitMap.isMarked(addr + 1),"Missing Printezis bit?")
ysr
parents:
2177
diff
changeset
|
9296 // Could be 0, if the block size could not be computed without stalling. |
| 0 | 9297 return res; |
| 9298 } | |
|
1703
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6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
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1579
diff
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|
9299 |
|
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
parents:
3293
diff
changeset
|
9300 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
|
9301 |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
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1579
diff
changeset
|
9302 switch (phase) { |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9303 case CMSCollector::InitialMarking: |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9304 initialize(true /* fullGC */ , |
|
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
parents:
3293
diff
changeset
|
9305 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
|
9306 true /* recordGCBeginTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9307 true /* recordPreGCUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9308 false /* recordPeakUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9309 false /* recordPostGCusage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9310 true /* recordAccumulatedGCTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9311 false /* recordGCEndTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
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1579
diff
changeset
|
9312 false /* countCollection */ ); |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9313 break; |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9314 |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9315 case CMSCollector::FinalMarking: |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9316 initialize(true /* fullGC */ , |
|
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
parents:
3293
diff
changeset
|
9317 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
|
9318 false /* recordGCBeginTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9319 false /* recordPreGCUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9320 false /* recordPeakUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9321 false /* recordPostGCusage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9322 true /* recordAccumulatedGCTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
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1579
diff
changeset
|
9323 false /* recordGCEndTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9324 false /* countCollection */ ); |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9325 break; |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9326 |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9327 case CMSCollector::Sweeping: |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9328 initialize(true /* fullGC */ , |
|
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
parents:
3293
diff
changeset
|
9329 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
|
9330 false /* recordGCBeginTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9331 false /* recordPreGCUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9332 true /* recordPeakUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9333 true /* recordPostGCusage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9334 false /* recordAccumulatedGCTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9335 true /* recordGCEndTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9336 true /* countCollection */ ); |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9337 break; |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9338 |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9339 default: |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9340 ShouldNotReachHere(); |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9341 } |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9342 } |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9343 |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9344 // when bailing out of cms in concurrent mode failure |
|
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
parents:
3293
diff
changeset
|
9345 TraceCMSMemoryManagerStats::TraceCMSMemoryManagerStats(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
|
9346 initialize(true /* fullGC */ , |
|
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
parents:
3293
diff
changeset
|
9347 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
|
9348 true /* recordGCBeginTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9349 true /* recordPreGCUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9350 true /* recordPeakUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9351 true /* recordPostGCusage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9352 true /* recordAccumulatedGCTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9353 true /* recordGCEndTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9354 true /* countCollection */ ); |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9355 } |