Mercurial > hg > truffle
annotate src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp @ 6885:685df3c6f84b
7045397: NPG: Add freelists to class loader arenas.
Reviewed-by: coleenp, stefank, jprovino, ohair
| author | jmasa |
|---|---|
| date | Tue, 18 Sep 2012 23:35:42 -0700 |
| parents | 633ba56cb013 |
| children | 0b54ffe4c2d3 203f64878aab |
| rev | line source |
|---|---|
| 0 | 1 /* |
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2 * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved. |
| 0 | 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 4 * | |
| 5 * This code is free software; you can redistribute it and/or modify it | |
| 6 * under the terms of the GNU General Public License version 2 only, as | |
| 7 * published by the Free Software Foundation. | |
| 8 * | |
| 9 * This code is distributed in the hope that it will be useful, but WITHOUT | |
| 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 12 * version 2 for more details (a copy is included in the LICENSE file that | |
| 13 * accompanied this code). | |
| 14 * | |
| 15 * You should have received a copy of the GNU General Public License version | |
| 16 * 2 along with this work; if not, write to the Free Software Foundation, | |
| 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
| 18 * | |
|
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
| 0 | 22 * |
| 23 */ | |
| 24 | |
| 1972 | 25 #include "precompiled.hpp" |
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26 #include "classfile/classLoaderData.hpp" |
| 1972 | 27 #include "classfile/symbolTable.hpp" |
| 28 #include "classfile/systemDictionary.hpp" | |
| 29 #include "code/codeCache.hpp" | |
| 30 #include "gc_implementation/concurrentMarkSweep/cmsAdaptiveSizePolicy.hpp" | |
| 31 #include "gc_implementation/concurrentMarkSweep/cmsCollectorPolicy.hpp" | |
| 32 #include "gc_implementation/concurrentMarkSweep/cmsGCAdaptivePolicyCounters.hpp" | |
| 33 #include "gc_implementation/concurrentMarkSweep/cmsOopClosures.inline.hpp" | |
| 34 #include "gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.hpp" | |
| 35 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.inline.hpp" | |
| 36 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp" | |
| 37 #include "gc_implementation/concurrentMarkSweep/vmCMSOperations.hpp" | |
| 38 #include "gc_implementation/parNew/parNewGeneration.hpp" | |
| 39 #include "gc_implementation/shared/collectorCounters.hpp" | |
| 40 #include "gc_implementation/shared/isGCActiveMark.hpp" | |
| 41 #include "gc_interface/collectedHeap.inline.hpp" | |
| 42 #include "memory/cardTableRS.hpp" | |
| 43 #include "memory/collectorPolicy.hpp" | |
| 44 #include "memory/gcLocker.inline.hpp" | |
| 45 #include "memory/genCollectedHeap.hpp" | |
| 46 #include "memory/genMarkSweep.hpp" | |
| 47 #include "memory/genOopClosures.inline.hpp" | |
| 48 #include "memory/iterator.hpp" | |
| 49 #include "memory/referencePolicy.hpp" | |
| 50 #include "memory/resourceArea.hpp" | |
| 51 #include "oops/oop.inline.hpp" | |
| 52 #include "prims/jvmtiExport.hpp" | |
| 53 #include "runtime/globals_extension.hpp" | |
| 54 #include "runtime/handles.inline.hpp" | |
| 55 #include "runtime/java.hpp" | |
| 56 #include "runtime/vmThread.hpp" | |
| 57 #include "services/memoryService.hpp" | |
| 58 #include "services/runtimeService.hpp" | |
| 0 | 59 |
| 60 // statics | |
| 61 CMSCollector* ConcurrentMarkSweepGeneration::_collector = NULL; | |
| 62 bool CMSCollector::_full_gc_requested = false; | |
| 63 | |
| 64 ////////////////////////////////////////////////////////////////// | |
| 65 // In support of CMS/VM thread synchronization | |
| 66 ////////////////////////////////////////////////////////////////// | |
| 67 // We split use of the CGC_lock into 2 "levels". | |
| 68 // The low-level locking is of the usual CGC_lock monitor. We introduce | |
| 69 // a higher level "token" (hereafter "CMS token") built on top of the | |
| 70 // low level monitor (hereafter "CGC lock"). | |
| 71 // The token-passing protocol gives priority to the VM thread. The | |
| 72 // CMS-lock doesn't provide any fairness guarantees, but clients | |
| 73 // should ensure that it is only held for very short, bounded | |
| 74 // durations. | |
| 75 // | |
| 76 // When either of the CMS thread or the VM thread is involved in | |
| 77 // collection operations during which it does not want the other | |
| 78 // thread to interfere, it obtains the CMS token. | |
| 79 // | |
| 80 // If either thread tries to get the token while the other has | |
| 81 // it, that thread waits. However, if the VM thread and CMS thread | |
| 82 // both want the token, then the VM thread gets priority while the | |
| 83 // CMS thread waits. This ensures, for instance, that the "concurrent" | |
| 84 // phases of the CMS thread's work do not block out the VM thread | |
| 85 // for long periods of time as the CMS thread continues to hog | |
| 86 // the token. (See bug 4616232). | |
| 87 // | |
| 88 // The baton-passing functions are, however, controlled by the | |
| 89 // flags _foregroundGCShouldWait and _foregroundGCIsActive, | |
| 90 // and here the low-level CMS lock, not the high level token, | |
| 91 // ensures mutual exclusion. | |
| 92 // | |
| 93 // Two important conditions that we have to satisfy: | |
| 94 // 1. if a thread does a low-level wait on the CMS lock, then it | |
| 95 // relinquishes the CMS token if it were holding that token | |
| 96 // when it acquired the low-level CMS lock. | |
| 97 // 2. any low-level notifications on the low-level lock | |
| 98 // should only be sent when a thread has relinquished the token. | |
| 99 // | |
| 100 // In the absence of either property, we'd have potential deadlock. | |
| 101 // | |
| 102 // We protect each of the CMS (concurrent and sequential) phases | |
| 103 // with the CMS _token_, not the CMS _lock_. | |
| 104 // | |
| 105 // The only code protected by CMS lock is the token acquisition code | |
| 106 // itself, see ConcurrentMarkSweepThread::[de]synchronize(), and the | |
| 107 // baton-passing code. | |
| 108 // | |
| 109 // Unfortunately, i couldn't come up with a good abstraction to factor and | |
| 110 // hide the naked CGC_lock manipulation in the baton-passing code | |
| 111 // further below. That's something we should try to do. Also, the proof | |
| 112 // of correctness of this 2-level locking scheme is far from obvious, | |
| 113 // and potentially quite slippery. We have an uneasy supsicion, for instance, | |
| 114 // that there may be a theoretical possibility of delay/starvation in the | |
| 115 // low-level lock/wait/notify scheme used for the baton-passing because of | |
| 116 // potential intereference with the priority scheme embodied in the | |
| 117 // CMS-token-passing protocol. See related comments at a CGC_lock->wait() | |
| 118 // invocation further below and marked with "XXX 20011219YSR". | |
| 119 // Indeed, as we note elsewhere, this may become yet more slippery | |
| 120 // in the presence of multiple CMS and/or multiple VM threads. XXX | |
| 121 | |
| 122 class CMSTokenSync: public StackObj { | |
| 123 private: | |
| 124 bool _is_cms_thread; | |
| 125 public: | |
| 126 CMSTokenSync(bool is_cms_thread): | |
| 127 _is_cms_thread(is_cms_thread) { | |
| 128 assert(is_cms_thread == Thread::current()->is_ConcurrentGC_thread(), | |
| 129 "Incorrect argument to constructor"); | |
| 130 ConcurrentMarkSweepThread::synchronize(_is_cms_thread); | |
| 131 } | |
| 132 | |
| 133 ~CMSTokenSync() { | |
| 134 assert(_is_cms_thread ? | |
| 135 ConcurrentMarkSweepThread::cms_thread_has_cms_token() : | |
| 136 ConcurrentMarkSweepThread::vm_thread_has_cms_token(), | |
| 137 "Incorrect state"); | |
| 138 ConcurrentMarkSweepThread::desynchronize(_is_cms_thread); | |
| 139 } | |
| 140 }; | |
| 141 | |
| 142 // Convenience class that does a CMSTokenSync, and then acquires | |
| 143 // upto three locks. | |
| 144 class CMSTokenSyncWithLocks: public CMSTokenSync { | |
| 145 private: | |
| 146 // Note: locks are acquired in textual declaration order | |
| 147 // and released in the opposite order | |
| 148 MutexLockerEx _locker1, _locker2, _locker3; | |
| 149 public: | |
| 150 CMSTokenSyncWithLocks(bool is_cms_thread, Mutex* mutex1, | |
| 151 Mutex* mutex2 = NULL, Mutex* mutex3 = NULL): | |
| 152 CMSTokenSync(is_cms_thread), | |
| 153 _locker1(mutex1, Mutex::_no_safepoint_check_flag), | |
| 154 _locker2(mutex2, Mutex::_no_safepoint_check_flag), | |
| 155 _locker3(mutex3, Mutex::_no_safepoint_check_flag) | |
| 156 { } | |
| 157 }; | |
| 158 | |
| 159 | |
| 160 // Wrapper class to temporarily disable icms during a foreground cms collection. | |
| 161 class ICMSDisabler: public StackObj { | |
| 162 public: | |
| 163 // The ctor disables icms and wakes up the thread so it notices the change; | |
| 164 // the dtor re-enables icms. Note that the CMSCollector methods will check | |
| 165 // CMSIncrementalMode. | |
| 166 ICMSDisabler() { CMSCollector::disable_icms(); CMSCollector::start_icms(); } | |
| 167 ~ICMSDisabler() { CMSCollector::enable_icms(); } | |
| 168 }; | |
| 169 | |
| 170 ////////////////////////////////////////////////////////////////// | |
| 171 // Concurrent Mark-Sweep Generation ///////////////////////////// | |
| 172 ////////////////////////////////////////////////////////////////// | |
| 173 | |
| 174 NOT_PRODUCT(CompactibleFreeListSpace* debug_cms_space;) | |
| 175 | |
| 176 // This struct contains per-thread things necessary to support parallel | |
| 177 // young-gen collection. | |
| 6197 | 178 class CMSParGCThreadState: public CHeapObj<mtGC> { |
| 0 | 179 public: |
| 180 CFLS_LAB lab; | |
| 181 PromotionInfo promo; | |
| 182 | |
| 183 // Constructor. | |
| 184 CMSParGCThreadState(CompactibleFreeListSpace* cfls) : lab(cfls) { | |
| 185 promo.setSpace(cfls); | |
| 186 } | |
| 187 }; | |
| 188 | |
| 189 ConcurrentMarkSweepGeneration::ConcurrentMarkSweepGeneration( | |
| 190 ReservedSpace rs, size_t initial_byte_size, int level, | |
| 191 CardTableRS* ct, bool use_adaptive_freelists, | |
| 6026 | 192 FreeBlockDictionary<FreeChunk>::DictionaryChoice dictionaryChoice) : |
| 0 | 193 CardGeneration(rs, initial_byte_size, level, ct), |
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194 _dilatation_factor(((double)MinChunkSize)/((double)(CollectedHeap::min_fill_size()))), |
| 0 | 195 _debug_collection_type(Concurrent_collection_type) |
| 196 { | |
| 197 HeapWord* bottom = (HeapWord*) _virtual_space.low(); | |
| 198 HeapWord* end = (HeapWord*) _virtual_space.high(); | |
| 199 | |
| 200 _direct_allocated_words = 0; | |
| 201 NOT_PRODUCT( | |
| 202 _numObjectsPromoted = 0; | |
| 203 _numWordsPromoted = 0; | |
| 204 _numObjectsAllocated = 0; | |
| 205 _numWordsAllocated = 0; | |
| 206 ) | |
| 207 | |
| 208 _cmsSpace = new CompactibleFreeListSpace(_bts, MemRegion(bottom, end), | |
| 209 use_adaptive_freelists, | |
| 210 dictionaryChoice); | |
| 211 NOT_PRODUCT(debug_cms_space = _cmsSpace;) | |
| 212 if (_cmsSpace == NULL) { | |
| 213 vm_exit_during_initialization( | |
| 214 "CompactibleFreeListSpace allocation failure"); | |
| 215 } | |
| 216 _cmsSpace->_gen = this; | |
| 217 | |
| 218 _gc_stats = new CMSGCStats(); | |
| 219 | |
| 220 // Verify the assumption that FreeChunk::_prev and OopDesc::_klass | |
| 221 // offsets match. The ability to tell free chunks from objects | |
| 222 // depends on this property. | |
| 223 debug_only( | |
| 224 FreeChunk* junk = NULL; | |
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225 assert(UseCompressedKlassPointers || |
| 187 | 226 junk->prev_addr() == (void*)(oop(junk)->klass_addr()), |
| 0 | 227 "Offset of FreeChunk::_prev within FreeChunk must match" |
| 228 " that of OopDesc::_klass within OopDesc"); | |
| 229 ) | |
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230 if (CollectedHeap::use_parallel_gc_threads()) { |
| 0 | 231 typedef CMSParGCThreadState* CMSParGCThreadStatePtr; |
| 232 _par_gc_thread_states = | |
| 6197 | 233 NEW_C_HEAP_ARRAY(CMSParGCThreadStatePtr, ParallelGCThreads, mtGC); |
| 0 | 234 if (_par_gc_thread_states == NULL) { |
| 235 vm_exit_during_initialization("Could not allocate par gc structs"); | |
| 236 } | |
| 237 for (uint i = 0; i < ParallelGCThreads; i++) { | |
| 238 _par_gc_thread_states[i] = new CMSParGCThreadState(cmsSpace()); | |
| 239 if (_par_gc_thread_states[i] == NULL) { | |
| 240 vm_exit_during_initialization("Could not allocate par gc structs"); | |
| 241 } | |
| 242 } | |
| 243 } else { | |
| 244 _par_gc_thread_states = NULL; | |
| 245 } | |
| 246 _incremental_collection_failed = false; | |
| 247 // The "dilatation_factor" is the expansion that can occur on | |
| 248 // account of the fact that the minimum object size in the CMS | |
| 249 // generation may be larger than that in, say, a contiguous young | |
| 250 // generation. | |
| 251 // Ideally, in the calculation below, we'd compute the dilatation | |
| 252 // factor as: MinChunkSize/(promoting_gen's min object size) | |
| 253 // Since we do not have such a general query interface for the | |
| 254 // promoting generation, we'll instead just use the mimimum | |
| 255 // object size (which today is a header's worth of space); | |
| 256 // note that all arithmetic is in units of HeapWords. | |
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257 assert(MinChunkSize >= CollectedHeap::min_fill_size(), "just checking"); |
| 0 | 258 assert(_dilatation_factor >= 1.0, "from previous assert"); |
| 259 } | |
| 260 | |
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261 |
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262 // The field "_initiating_occupancy" represents the occupancy percentage |
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263 // at which we trigger a new collection cycle. Unless explicitly specified |
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264 // via CMSInitiatingOccupancyFraction (argument "io" below), it |
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265 // is calculated by: |
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266 // |
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267 // Let "f" be MinHeapFreeRatio in |
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268 // |
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269 // _intiating_occupancy = 100-f + |
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270 // f * (CMSTriggerRatio/100) |
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271 // where CMSTriggerRatio is the argument "tr" below. |
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272 // |
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273 // That is, if we assume the heap is at its desired maximum occupancy at the |
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274 // end of a collection, we let CMSTriggerRatio of the (purported) free |
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275 // space be allocated before initiating a new collection cycle. |
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276 // |
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277 void ConcurrentMarkSweepGeneration::init_initiating_occupancy(intx io, intx tr) { |
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278 assert(io <= 100 && tr >= 0 && tr <= 100, "Check the arguments"); |
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279 if (io >= 0) { |
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280 _initiating_occupancy = (double)io / 100.0; |
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281 } else { |
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282 _initiating_occupancy = ((100 - MinHeapFreeRatio) + |
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283 (double)(tr * MinHeapFreeRatio) / 100.0) |
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284 / 100.0; |
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285 } |
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286 } |
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287 |
| 0 | 288 void ConcurrentMarkSweepGeneration::ref_processor_init() { |
| 289 assert(collector() != NULL, "no collector"); | |
| 290 collector()->ref_processor_init(); | |
| 291 } | |
| 292 | |
| 293 void CMSCollector::ref_processor_init() { | |
| 294 if (_ref_processor == NULL) { | |
| 295 // Allocate and initialize a reference processor | |
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296 _ref_processor = |
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297 new ReferenceProcessor(_span, // span |
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298 (ParallelGCThreads > 1) && ParallelRefProcEnabled, // mt processing |
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299 (int) ParallelGCThreads, // mt processing degree |
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300 _cmsGen->refs_discovery_is_mt(), // mt discovery |
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301 (int) MAX2(ConcGCThreads, ParallelGCThreads), // mt discovery degree |
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302 _cmsGen->refs_discovery_is_atomic(), // discovery is not atomic |
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303 &_is_alive_closure, // closure for liveness info |
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304 false); // next field updates do not need write barrier |
| 0 | 305 // Initialize the _ref_processor field of CMSGen |
| 306 _cmsGen->set_ref_processor(_ref_processor); | |
| 307 | |
| 308 } | |
| 309 } | |
| 310 | |
| 311 CMSAdaptiveSizePolicy* CMSCollector::size_policy() { | |
| 312 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 313 assert(gch->kind() == CollectedHeap::GenCollectedHeap, | |
| 314 "Wrong type of heap"); | |
| 315 CMSAdaptiveSizePolicy* sp = (CMSAdaptiveSizePolicy*) | |
| 316 gch->gen_policy()->size_policy(); | |
| 317 assert(sp->is_gc_cms_adaptive_size_policy(), | |
| 318 "Wrong type of size policy"); | |
| 319 return sp; | |
| 320 } | |
| 321 | |
| 322 CMSGCAdaptivePolicyCounters* CMSCollector::gc_adaptive_policy_counters() { | |
| 323 CMSGCAdaptivePolicyCounters* results = | |
| 324 (CMSGCAdaptivePolicyCounters*) collector_policy()->counters(); | |
| 325 assert( | |
| 326 results->kind() == GCPolicyCounters::CMSGCAdaptivePolicyCountersKind, | |
| 327 "Wrong gc policy counter kind"); | |
| 328 return results; | |
| 329 } | |
| 330 | |
| 331 | |
| 332 void ConcurrentMarkSweepGeneration::initialize_performance_counters() { | |
| 333 | |
| 334 const char* gen_name = "old"; | |
| 335 | |
| 336 // Generation Counters - generation 1, 1 subspace | |
| 337 _gen_counters = new GenerationCounters(gen_name, 1, 1, &_virtual_space); | |
| 338 | |
| 339 _space_counters = new GSpaceCounters(gen_name, 0, | |
| 340 _virtual_space.reserved_size(), | |
| 341 this, _gen_counters); | |
| 342 } | |
| 343 | |
| 344 CMSStats::CMSStats(ConcurrentMarkSweepGeneration* cms_gen, unsigned int alpha): | |
| 345 _cms_gen(cms_gen) | |
| 346 { | |
| 347 assert(alpha <= 100, "bad value"); | |
| 348 _saved_alpha = alpha; | |
| 349 | |
| 350 // Initialize the alphas to the bootstrap value of 100. | |
| 351 _gc0_alpha = _cms_alpha = 100; | |
| 352 | |
| 353 _cms_begin_time.update(); | |
| 354 _cms_end_time.update(); | |
| 355 | |
| 356 _gc0_duration = 0.0; | |
| 357 _gc0_period = 0.0; | |
| 358 _gc0_promoted = 0; | |
| 359 | |
| 360 _cms_duration = 0.0; | |
| 361 _cms_period = 0.0; | |
| 362 _cms_allocated = 0; | |
| 363 | |
| 364 _cms_used_at_gc0_begin = 0; | |
| 365 _cms_used_at_gc0_end = 0; | |
| 366 _allow_duty_cycle_reduction = false; | |
| 367 _valid_bits = 0; | |
| 368 _icms_duty_cycle = CMSIncrementalDutyCycle; | |
| 369 } | |
| 370 | |
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371 double CMSStats::cms_free_adjustment_factor(size_t free) const { |
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372 // TBD: CR 6909490 |
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373 return 1.0; |
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374 } |
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375 |
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376 void CMSStats::adjust_cms_free_adjustment_factor(bool fail, size_t free) { |
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377 } |
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378 |
| 0 | 379 // If promotion failure handling is on use |
| 380 // the padded average size of the promotion for each | |
| 381 // young generation collection. | |
| 382 double CMSStats::time_until_cms_gen_full() const { | |
| 383 size_t cms_free = _cms_gen->cmsSpace()->free(); | |
| 384 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
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385 size_t expected_promotion = MIN2(gch->get_gen(0)->capacity(), |
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386 (size_t) _cms_gen->gc_stats()->avg_promoted()->padded_average()); |
| 0 | 387 if (cms_free > expected_promotion) { |
| 388 // Start a cms collection if there isn't enough space to promote | |
| 389 // for the next minor collection. Use the padded average as | |
| 390 // a safety factor. | |
| 391 cms_free -= expected_promotion; | |
| 392 | |
| 393 // Adjust by the safety factor. | |
| 394 double cms_free_dbl = (double)cms_free; | |
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395 double cms_adjustment = (100.0 - CMSIncrementalSafetyFactor)/100.0; |
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396 // Apply a further correction factor which tries to adjust |
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397 // for recent occurance of concurrent mode failures. |
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398 cms_adjustment = cms_adjustment * cms_free_adjustment_factor(cms_free); |
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399 cms_free_dbl = cms_free_dbl * cms_adjustment; |
| 0 | 400 |
| 401 if (PrintGCDetails && Verbose) { | |
| 402 gclog_or_tty->print_cr("CMSStats::time_until_cms_gen_full: cms_free " | |
| 403 SIZE_FORMAT " expected_promotion " SIZE_FORMAT, | |
| 404 cms_free, expected_promotion); | |
| 405 gclog_or_tty->print_cr(" cms_free_dbl %f cms_consumption_rate %f", | |
| 406 cms_free_dbl, cms_consumption_rate() + 1.0); | |
| 407 } | |
| 408 // Add 1 in case the consumption rate goes to zero. | |
| 409 return cms_free_dbl / (cms_consumption_rate() + 1.0); | |
| 410 } | |
| 411 return 0.0; | |
| 412 } | |
| 413 | |
| 414 // Compare the duration of the cms collection to the | |
| 415 // time remaining before the cms generation is empty. | |
| 416 // Note that the time from the start of the cms collection | |
| 417 // to the start of the cms sweep (less than the total | |
| 418 // duration of the cms collection) can be used. This | |
| 419 // has been tried and some applications experienced | |
| 420 // promotion failures early in execution. This was | |
| 421 // possibly because the averages were not accurate | |
| 422 // enough at the beginning. | |
| 423 double CMSStats::time_until_cms_start() const { | |
| 424 // We add "gc0_period" to the "work" calculation | |
| 425 // below because this query is done (mostly) at the | |
| 426 // end of a scavenge, so we need to conservatively | |
| 427 // account for that much possible delay | |
| 428 // in the query so as to avoid concurrent mode failures | |
| 429 // due to starting the collection just a wee bit too | |
| 430 // late. | |
| 431 double work = cms_duration() + gc0_period(); | |
| 432 double deadline = time_until_cms_gen_full(); | |
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433 // If a concurrent mode failure occurred recently, we want to be |
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434 // more conservative and halve our expected time_until_cms_gen_full() |
| 0 | 435 if (work > deadline) { |
| 436 if (Verbose && PrintGCDetails) { | |
| 437 gclog_or_tty->print( | |
| 438 " CMSCollector: collect because of anticipated promotion " | |
| 439 "before full %3.7f + %3.7f > %3.7f ", cms_duration(), | |
| 440 gc0_period(), time_until_cms_gen_full()); | |
| 441 } | |
| 442 return 0.0; | |
| 443 } | |
| 444 return work - deadline; | |
| 445 } | |
| 446 | |
| 447 // Return a duty cycle based on old_duty_cycle and new_duty_cycle, limiting the | |
| 448 // amount of change to prevent wild oscillation. | |
| 449 unsigned int CMSStats::icms_damped_duty_cycle(unsigned int old_duty_cycle, | |
| 450 unsigned int new_duty_cycle) { | |
| 451 assert(old_duty_cycle <= 100, "bad input value"); | |
| 452 assert(new_duty_cycle <= 100, "bad input value"); | |
| 453 | |
| 454 // Note: use subtraction with caution since it may underflow (values are | |
| 455 // unsigned). Addition is safe since we're in the range 0-100. | |
| 456 unsigned int damped_duty_cycle = new_duty_cycle; | |
| 457 if (new_duty_cycle < old_duty_cycle) { | |
| 458 const unsigned int largest_delta = MAX2(old_duty_cycle / 4, 5U); | |
| 459 if (new_duty_cycle + largest_delta < old_duty_cycle) { | |
| 460 damped_duty_cycle = old_duty_cycle - largest_delta; | |
| 461 } | |
| 462 } else if (new_duty_cycle > old_duty_cycle) { | |
| 463 const unsigned int largest_delta = MAX2(old_duty_cycle / 4, 15U); | |
| 464 if (new_duty_cycle > old_duty_cycle + largest_delta) { | |
| 465 damped_duty_cycle = MIN2(old_duty_cycle + largest_delta, 100U); | |
| 466 } | |
| 467 } | |
| 468 assert(damped_duty_cycle <= 100, "invalid duty cycle computed"); | |
| 469 | |
| 470 if (CMSTraceIncrementalPacing) { | |
| 471 gclog_or_tty->print(" [icms_damped_duty_cycle(%d,%d) = %d] ", | |
| 472 old_duty_cycle, new_duty_cycle, damped_duty_cycle); | |
| 473 } | |
| 474 return damped_duty_cycle; | |
| 475 } | |
| 476 | |
| 477 unsigned int CMSStats::icms_update_duty_cycle_impl() { | |
| 478 assert(CMSIncrementalPacing && valid(), | |
| 479 "should be handled in icms_update_duty_cycle()"); | |
| 480 | |
| 481 double cms_time_so_far = cms_timer().seconds(); | |
| 482 double scaled_duration = cms_duration_per_mb() * _cms_used_at_gc0_end / M; | |
| 483 double scaled_duration_remaining = fabsd(scaled_duration - cms_time_so_far); | |
| 484 | |
| 485 // Avoid division by 0. | |
| 486 double time_until_full = MAX2(time_until_cms_gen_full(), 0.01); | |
| 487 double duty_cycle_dbl = 100.0 * scaled_duration_remaining / time_until_full; | |
| 488 | |
| 489 unsigned int new_duty_cycle = MIN2((unsigned int)duty_cycle_dbl, 100U); | |
| 490 if (new_duty_cycle > _icms_duty_cycle) { | |
| 491 // Avoid very small duty cycles (1 or 2); 0 is allowed. | |
| 492 if (new_duty_cycle > 2) { | |
| 493 _icms_duty_cycle = icms_damped_duty_cycle(_icms_duty_cycle, | |
| 494 new_duty_cycle); | |
| 495 } | |
| 496 } else if (_allow_duty_cycle_reduction) { | |
| 497 // The duty cycle is reduced only once per cms cycle (see record_cms_end()). | |
| 498 new_duty_cycle = icms_damped_duty_cycle(_icms_duty_cycle, new_duty_cycle); | |
| 499 // Respect the minimum duty cycle. | |
| 500 unsigned int min_duty_cycle = (unsigned int)CMSIncrementalDutyCycleMin; | |
| 501 _icms_duty_cycle = MAX2(new_duty_cycle, min_duty_cycle); | |
| 502 } | |
| 503 | |
| 504 if (PrintGCDetails || CMSTraceIncrementalPacing) { | |
| 505 gclog_or_tty->print(" icms_dc=%d ", _icms_duty_cycle); | |
| 506 } | |
| 507 | |
| 508 _allow_duty_cycle_reduction = false; | |
| 509 return _icms_duty_cycle; | |
| 510 } | |
| 511 | |
| 512 #ifndef PRODUCT | |
| 513 void CMSStats::print_on(outputStream *st) const { | |
| 514 st->print(" gc0_alpha=%d,cms_alpha=%d", _gc0_alpha, _cms_alpha); | |
| 515 st->print(",gc0_dur=%g,gc0_per=%g,gc0_promo=" SIZE_FORMAT, | |
| 516 gc0_duration(), gc0_period(), gc0_promoted()); | |
| 517 st->print(",cms_dur=%g,cms_dur_per_mb=%g,cms_per=%g,cms_alloc=" SIZE_FORMAT, | |
| 518 cms_duration(), cms_duration_per_mb(), | |
| 519 cms_period(), cms_allocated()); | |
| 520 st->print(",cms_since_beg=%g,cms_since_end=%g", | |
| 521 cms_time_since_begin(), cms_time_since_end()); | |
| 522 st->print(",cms_used_beg=" SIZE_FORMAT ",cms_used_end=" SIZE_FORMAT, | |
| 523 _cms_used_at_gc0_begin, _cms_used_at_gc0_end); | |
| 524 if (CMSIncrementalMode) { | |
| 525 st->print(",dc=%d", icms_duty_cycle()); | |
| 526 } | |
| 527 | |
| 528 if (valid()) { | |
| 529 st->print(",promo_rate=%g,cms_alloc_rate=%g", | |
| 530 promotion_rate(), cms_allocation_rate()); | |
| 531 st->print(",cms_consumption_rate=%g,time_until_full=%g", | |
| 532 cms_consumption_rate(), time_until_cms_gen_full()); | |
| 533 } | |
| 534 st->print(" "); | |
| 535 } | |
| 536 #endif // #ifndef PRODUCT | |
| 537 | |
| 538 CMSCollector::CollectorState CMSCollector::_collectorState = | |
| 539 CMSCollector::Idling; | |
| 540 bool CMSCollector::_foregroundGCIsActive = false; | |
| 541 bool CMSCollector::_foregroundGCShouldWait = false; | |
| 542 | |
| 543 CMSCollector::CMSCollector(ConcurrentMarkSweepGeneration* cmsGen, | |
| 544 CardTableRS* ct, | |
| 545 ConcurrentMarkSweepPolicy* cp): | |
| 546 _cmsGen(cmsGen), | |
| 547 _ct(ct), | |
| 548 _ref_processor(NULL), // will be set later | |
| 549 _conc_workers(NULL), // may be set later | |
| 550 _abort_preclean(false), | |
| 551 _start_sampling(false), | |
| 552 _between_prologue_and_epilogue(false), | |
| 553 _markBitMap(0, Mutex::leaf + 1, "CMS_markBitMap_lock"), | |
| 554 _modUnionTable((CardTableModRefBS::card_shift - LogHeapWordSize), | |
| 555 -1 /* lock-free */, "No_lock" /* dummy */), | |
| 556 _modUnionClosure(&_modUnionTable), | |
| 557 _modUnionClosurePar(&_modUnionTable), | |
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558 // Adjust my span to cover old (cms) gen |
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559 _span(cmsGen->reserved()), |
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560 // Construct the is_alive_closure with _span & markBitMap |
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561 _is_alive_closure(_span, &_markBitMap), |
| 0 | 562 _restart_addr(NULL), |
| 563 _overflow_list(NULL), | |
| 564 _stats(cmsGen), | |
| 565 _eden_chunk_array(NULL), // may be set in ctor body | |
| 566 _eden_chunk_capacity(0), // -- ditto -- | |
| 567 _eden_chunk_index(0), // -- ditto -- | |
| 568 _survivor_plab_array(NULL), // -- ditto -- | |
| 569 _survivor_chunk_array(NULL), // -- ditto -- | |
| 570 _survivor_chunk_capacity(0), // -- ditto -- | |
| 571 _survivor_chunk_index(0), // -- ditto -- | |
| 572 _ser_pmc_preclean_ovflw(0), | |
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573 _ser_kac_preclean_ovflw(0), |
| 0 | 574 _ser_pmc_remark_ovflw(0), |
| 575 _par_pmc_remark_ovflw(0), | |
| 576 _ser_kac_ovflw(0), | |
| 577 _par_kac_ovflw(0), | |
| 578 #ifndef PRODUCT | |
| 579 _num_par_pushes(0), | |
| 580 #endif | |
| 581 _collection_count_start(0), | |
| 582 _verifying(false), | |
| 583 _icms_start_limit(NULL), | |
| 584 _icms_stop_limit(NULL), | |
| 585 _verification_mark_bm(0, Mutex::leaf + 1, "CMS_verification_mark_bm_lock"), | |
| 586 _completed_initialization(false), | |
| 587 _collector_policy(cp), | |
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588 _should_unload_classes(false), |
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589 _concurrent_cycles_since_last_unload(0), |
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590 _roots_scanning_options(0), |
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591 _inter_sweep_estimate(CMS_SweepWeight, CMS_SweepPadding), |
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592 _intra_sweep_estimate(CMS_SweepWeight, CMS_SweepPadding) |
| 0 | 593 { |
| 594 if (ExplicitGCInvokesConcurrentAndUnloadsClasses) { | |
| 595 ExplicitGCInvokesConcurrent = true; | |
| 596 } | |
| 597 // Now expand the span and allocate the collection support structures | |
| 598 // (MUT, marking bit map etc.) to cover both generations subject to | |
| 599 // collection. | |
| 600 | |
| 601 // For use by dirty card to oop closures. | |
| 602 _cmsGen->cmsSpace()->set_collector(this); | |
| 603 | |
| 604 // Allocate MUT and marking bit map | |
| 605 { | |
| 606 MutexLockerEx x(_markBitMap.lock(), Mutex::_no_safepoint_check_flag); | |
| 607 if (!_markBitMap.allocate(_span)) { | |
| 608 warning("Failed to allocate CMS Bit Map"); | |
| 609 return; | |
| 610 } | |
| 611 assert(_markBitMap.covers(_span), "_markBitMap inconsistency?"); | |
| 612 } | |
| 613 { | |
| 614 _modUnionTable.allocate(_span); | |
| 615 assert(_modUnionTable.covers(_span), "_modUnionTable inconsistency?"); | |
| 616 } | |
| 617 | |
| 1284 | 618 if (!_markStack.allocate(MarkStackSize)) { |
| 0 | 619 warning("Failed to allocate CMS Marking Stack"); |
| 620 return; | |
| 621 } | |
| 622 | |
| 623 // Support for multi-threaded concurrent phases | |
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624 if (CMSConcurrentMTEnabled) { |
| 1284 | 625 if (FLAG_IS_DEFAULT(ConcGCThreads)) { |
| 0 | 626 // just for now |
| 1284 | 627 FLAG_SET_DEFAULT(ConcGCThreads, (ParallelGCThreads + 3)/4); |
| 628 } | |
| 629 if (ConcGCThreads > 1) { | |
| 0 | 630 _conc_workers = new YieldingFlexibleWorkGang("Parallel CMS Threads", |
| 1284 | 631 ConcGCThreads, true); |
| 0 | 632 if (_conc_workers == NULL) { |
| 633 warning("GC/CMS: _conc_workers allocation failure: " | |
| 634 "forcing -CMSConcurrentMTEnabled"); | |
| 635 CMSConcurrentMTEnabled = false; | |
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636 } else { |
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637 _conc_workers->initialize_workers(); |
| 0 | 638 } |
| 639 } else { | |
| 640 CMSConcurrentMTEnabled = false; | |
| 641 } | |
| 642 } | |
| 643 if (!CMSConcurrentMTEnabled) { | |
| 1284 | 644 ConcGCThreads = 0; |
| 0 | 645 } else { |
| 646 // Turn off CMSCleanOnEnter optimization temporarily for | |
| 647 // the MT case where it's not fixed yet; see 6178663. | |
| 648 CMSCleanOnEnter = false; | |
| 649 } | |
| 1284 | 650 assert((_conc_workers != NULL) == (ConcGCThreads > 1), |
| 0 | 651 "Inconsistency"); |
| 652 | |
| 653 // Parallel task queues; these are shared for the | |
| 654 // concurrent and stop-world phases of CMS, but | |
| 655 // are not shared with parallel scavenge (ParNew). | |
| 656 { | |
| 657 uint i; | |
| 1284 | 658 uint num_queues = (uint) MAX2(ParallelGCThreads, ConcGCThreads); |
| 0 | 659 |
| 660 if ((CMSParallelRemarkEnabled || CMSConcurrentMTEnabled | |
| 661 || ParallelRefProcEnabled) | |
| 662 && num_queues > 0) { | |
| 663 _task_queues = new OopTaskQueueSet(num_queues); | |
| 664 if (_task_queues == NULL) { | |
| 665 warning("task_queues allocation failure."); | |
| 666 return; | |
| 667 } | |
| 6197 | 668 _hash_seed = NEW_C_HEAP_ARRAY(int, num_queues, mtGC); |
| 0 | 669 if (_hash_seed == NULL) { |
| 670 warning("_hash_seed array allocation failure"); | |
| 671 return; | |
| 672 } | |
| 673 | |
| 1665 | 674 typedef Padded<OopTaskQueue> PaddedOopTaskQueue; |
| 0 | 675 for (i = 0; i < num_queues; i++) { |
| 1665 | 676 PaddedOopTaskQueue *q = new PaddedOopTaskQueue(); |
| 677 if (q == NULL) { | |
| 0 | 678 warning("work_queue allocation failure."); |
| 679 return; | |
| 680 } | |
| 1665 | 681 _task_queues->register_queue(i, q); |
| 0 | 682 } |
| 683 for (i = 0; i < num_queues; i++) { | |
| 684 _task_queues->queue(i)->initialize(); | |
| 685 _hash_seed[i] = 17; // copied from ParNew | |
| 686 } | |
| 687 } | |
| 688 } | |
| 689 | |
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690 _cmsGen ->init_initiating_occupancy(CMSInitiatingOccupancyFraction, CMSTriggerRatio); |
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691 |
| 0 | 692 // Clip CMSBootstrapOccupancy between 0 and 100. |
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693 _bootstrap_occupancy = ((double)MIN2((uintx)100, MAX2((uintx)0, CMSBootstrapOccupancy))) |
| 0 | 694 /(double)100; |
| 695 | |
| 696 _full_gcs_since_conc_gc = 0; | |
| 697 | |
| 698 // Now tell CMS generations the identity of their collector | |
| 699 ConcurrentMarkSweepGeneration::set_collector(this); | |
| 700 | |
| 701 // Create & start a CMS thread for this CMS collector | |
| 702 _cmsThread = ConcurrentMarkSweepThread::start(this); | |
| 703 assert(cmsThread() != NULL, "CMS Thread should have been created"); | |
| 704 assert(cmsThread()->collector() == this, | |
| 705 "CMS Thread should refer to this gen"); | |
| 706 assert(CGC_lock != NULL, "Where's the CGC_lock?"); | |
| 707 | |
| 708 // Support for parallelizing young gen rescan | |
| 709 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 710 _young_gen = gch->prev_gen(_cmsGen); | |
| 711 if (gch->supports_inline_contig_alloc()) { | |
| 712 _top_addr = gch->top_addr(); | |
| 713 _end_addr = gch->end_addr(); | |
| 714 assert(_young_gen != NULL, "no _young_gen"); | |
| 715 _eden_chunk_index = 0; | |
| 716 _eden_chunk_capacity = (_young_gen->max_capacity()+CMSSamplingGrain)/CMSSamplingGrain; | |
| 6197 | 717 _eden_chunk_array = NEW_C_HEAP_ARRAY(HeapWord*, _eden_chunk_capacity, mtGC); |
| 0 | 718 if (_eden_chunk_array == NULL) { |
| 719 _eden_chunk_capacity = 0; | |
| 720 warning("GC/CMS: _eden_chunk_array allocation failure"); | |
| 721 } | |
| 722 } | |
| 723 assert(_eden_chunk_array != NULL || _eden_chunk_capacity == 0, "Error"); | |
| 724 | |
| 725 // Support for parallelizing survivor space rescan | |
| 726 if (CMSParallelRemarkEnabled && CMSParallelSurvivorRemarkEnabled) { | |
|
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727 const size_t max_plab_samples = |
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728 ((DefNewGeneration*)_young_gen)->max_survivor_size()/MinTLABSize; |
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729 |
| 6197 | 730 _survivor_plab_array = NEW_C_HEAP_ARRAY(ChunkArray, ParallelGCThreads, mtGC); |
| 731 _survivor_chunk_array = NEW_C_HEAP_ARRAY(HeapWord*, 2*max_plab_samples, mtGC); | |
| 732 _cursor = NEW_C_HEAP_ARRAY(size_t, ParallelGCThreads, mtGC); | |
| 0 | 733 if (_survivor_plab_array == NULL || _survivor_chunk_array == NULL |
| 734 || _cursor == NULL) { | |
| 735 warning("Failed to allocate survivor plab/chunk array"); | |
| 736 if (_survivor_plab_array != NULL) { | |
| 6197 | 737 FREE_C_HEAP_ARRAY(ChunkArray, _survivor_plab_array, mtGC); |
| 0 | 738 _survivor_plab_array = NULL; |
| 739 } | |
| 740 if (_survivor_chunk_array != NULL) { | |
| 6197 | 741 FREE_C_HEAP_ARRAY(HeapWord*, _survivor_chunk_array, mtGC); |
| 0 | 742 _survivor_chunk_array = NULL; |
| 743 } | |
| 744 if (_cursor != NULL) { | |
| 6197 | 745 FREE_C_HEAP_ARRAY(size_t, _cursor, mtGC); |
| 0 | 746 _cursor = NULL; |
| 747 } | |
| 748 } else { | |
| 749 _survivor_chunk_capacity = 2*max_plab_samples; | |
| 750 for (uint i = 0; i < ParallelGCThreads; i++) { | |
| 6197 | 751 HeapWord** vec = NEW_C_HEAP_ARRAY(HeapWord*, max_plab_samples, mtGC); |
| 0 | 752 if (vec == NULL) { |
| 753 warning("Failed to allocate survivor plab array"); | |
| 754 for (int j = i; j > 0; j--) { | |
| 6197 | 755 FREE_C_HEAP_ARRAY(HeapWord*, _survivor_plab_array[j-1].array(), mtGC); |
| 0 | 756 } |
| 6197 | 757 FREE_C_HEAP_ARRAY(ChunkArray, _survivor_plab_array, mtGC); |
| 758 FREE_C_HEAP_ARRAY(HeapWord*, _survivor_chunk_array, mtGC); | |
| 0 | 759 _survivor_plab_array = NULL; |
| 760 _survivor_chunk_array = NULL; | |
| 761 _survivor_chunk_capacity = 0; | |
| 762 break; | |
| 763 } else { | |
| 764 ChunkArray* cur = | |
| 765 ::new (&_survivor_plab_array[i]) ChunkArray(vec, | |
| 766 max_plab_samples); | |
| 767 assert(cur->end() == 0, "Should be 0"); | |
| 768 assert(cur->array() == vec, "Should be vec"); | |
| 769 assert(cur->capacity() == max_plab_samples, "Error"); | |
| 770 } | |
| 771 } | |
| 772 } | |
| 773 } | |
| 774 assert( ( _survivor_plab_array != NULL | |
| 775 && _survivor_chunk_array != NULL) | |
| 776 || ( _survivor_chunk_capacity == 0 | |
| 777 && _survivor_chunk_index == 0), | |
| 778 "Error"); | |
| 779 | |
| 780 // Choose what strong roots should be scanned depending on verification options | |
| 781 if (!CMSClassUnloadingEnabled) { | |
| 782 // If class unloading is disabled we want to include all classes into the root set. | |
| 783 add_root_scanning_option(SharedHeap::SO_AllClasses); | |
| 784 } else { | |
| 785 add_root_scanning_option(SharedHeap::SO_SystemClasses); | |
| 786 } | |
| 787 | |
| 788 NOT_PRODUCT(_overflow_counter = CMSMarkStackOverflowInterval;) | |
| 789 _gc_counters = new CollectorCounters("CMS", 1); | |
| 790 _completed_initialization = true; | |
|
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791 _inter_sweep_timer.start(); // start of time |
| 0 | 792 } |
| 793 | |
| 794 const char* ConcurrentMarkSweepGeneration::name() const { | |
| 795 return "concurrent mark-sweep generation"; | |
| 796 } | |
| 797 void ConcurrentMarkSweepGeneration::update_counters() { | |
| 798 if (UsePerfData) { | |
| 799 _space_counters->update_all(); | |
| 800 _gen_counters->update_all(); | |
| 801 } | |
| 802 } | |
| 803 | |
| 804 // this is an optimized version of update_counters(). it takes the | |
| 805 // used value as a parameter rather than computing it. | |
| 806 // | |
| 807 void ConcurrentMarkSweepGeneration::update_counters(size_t used) { | |
| 808 if (UsePerfData) { | |
| 809 _space_counters->update_used(used); | |
| 810 _space_counters->update_capacity(); | |
| 811 _gen_counters->update_all(); | |
| 812 } | |
| 813 } | |
| 814 | |
| 815 void ConcurrentMarkSweepGeneration::print() const { | |
| 816 Generation::print(); | |
| 817 cmsSpace()->print(); | |
| 818 } | |
| 819 | |
| 820 #ifndef PRODUCT | |
| 821 void ConcurrentMarkSweepGeneration::print_statistics() { | |
| 822 cmsSpace()->printFLCensus(0); | |
| 823 } | |
| 824 #endif | |
| 825 | |
| 826 void ConcurrentMarkSweepGeneration::printOccupancy(const char *s) { | |
| 827 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 828 if (PrintGCDetails) { | |
| 829 if (Verbose) { | |
| 830 gclog_or_tty->print(" [%d %s-%s: "SIZE_FORMAT"("SIZE_FORMAT")]", | |
| 831 level(), short_name(), s, used(), capacity()); | |
| 832 } else { | |
| 833 gclog_or_tty->print(" [%d %s-%s: "SIZE_FORMAT"K("SIZE_FORMAT"K)]", | |
| 834 level(), short_name(), s, used() / K, capacity() / K); | |
| 835 } | |
| 836 } | |
| 837 if (Verbose) { | |
| 838 gclog_or_tty->print(" "SIZE_FORMAT"("SIZE_FORMAT")", | |
| 839 gch->used(), gch->capacity()); | |
| 840 } else { | |
| 841 gclog_or_tty->print(" "SIZE_FORMAT"K("SIZE_FORMAT"K)", | |
| 842 gch->used() / K, gch->capacity() / K); | |
| 843 } | |
| 844 } | |
| 845 | |
| 846 size_t | |
| 847 ConcurrentMarkSweepGeneration::contiguous_available() const { | |
| 848 // dld proposes an improvement in precision here. If the committed | |
| 849 // part of the space ends in a free block we should add that to | |
| 850 // uncommitted size in the calculation below. Will make this | |
| 851 // change later, staying with the approximation below for the | |
| 852 // time being. -- ysr. | |
| 853 return MAX2(_virtual_space.uncommitted_size(), unsafe_max_alloc_nogc()); | |
| 854 } | |
| 855 | |
| 856 size_t | |
| 857 ConcurrentMarkSweepGeneration::unsafe_max_alloc_nogc() const { | |
| 858 return _cmsSpace->max_alloc_in_words() * HeapWordSize; | |
| 859 } | |
| 860 | |
| 861 size_t ConcurrentMarkSweepGeneration::max_available() const { | |
| 862 return free() + _virtual_space.uncommitted_size(); | |
| 863 } | |
| 864 | |
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865 bool ConcurrentMarkSweepGeneration::promotion_attempt_is_safe(size_t max_promotion_in_bytes) const { |
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866 size_t available = max_available(); |
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867 size_t av_promo = (size_t)gc_stats()->avg_promoted()->padded_average(); |
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868 bool res = (available >= av_promo) || (available >= max_promotion_in_bytes); |
|
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869 if (Verbose && PrintGCDetails) { |
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870 gclog_or_tty->print_cr( |
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871 "CMS: promo attempt is%s safe: available("SIZE_FORMAT") %s av_promo("SIZE_FORMAT")," |
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872 "max_promo("SIZE_FORMAT")", |
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873 res? "":" not", available, res? ">=":"<", |
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874 av_promo, max_promotion_in_bytes); |
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875 } |
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876 return res; |
| 0 | 877 } |
| 878 | |
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879 // At a promotion failure dump information on block layout in heap |
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880 // (cms old generation). |
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881 void ConcurrentMarkSweepGeneration::promotion_failure_occurred() { |
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882 if (CMSDumpAtPromotionFailure) { |
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883 cmsSpace()->dump_at_safepoint_with_locks(collector(), gclog_or_tty); |
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884 } |
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885 } |
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886 |
| 0 | 887 CompactibleSpace* |
| 888 ConcurrentMarkSweepGeneration::first_compaction_space() const { | |
| 889 return _cmsSpace; | |
| 890 } | |
| 891 | |
| 892 void ConcurrentMarkSweepGeneration::reset_after_compaction() { | |
| 893 // Clear the promotion information. These pointers can be adjusted | |
| 894 // along with all the other pointers into the heap but | |
| 895 // compaction is expected to be a rare event with | |
| 896 // a heap using cms so don't do it without seeing the need. | |
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897 if (CollectedHeap::use_parallel_gc_threads()) { |
| 0 | 898 for (uint i = 0; i < ParallelGCThreads; i++) { |
| 899 _par_gc_thread_states[i]->promo.reset(); | |
| 900 } | |
| 901 } | |
| 902 } | |
| 903 | |
| 904 void ConcurrentMarkSweepGeneration::space_iterate(SpaceClosure* blk, bool usedOnly) { | |
| 905 blk->do_space(_cmsSpace); | |
| 906 } | |
| 907 | |
| 908 void ConcurrentMarkSweepGeneration::compute_new_size() { | |
| 909 assert_locked_or_safepoint(Heap_lock); | |
| 910 | |
| 911 // If incremental collection failed, we just want to expand | |
| 912 // to the limit. | |
| 913 if (incremental_collection_failed()) { | |
| 914 clear_incremental_collection_failed(); | |
| 915 grow_to_reserved(); | |
| 916 return; | |
| 917 } | |
| 918 | |
| 919 size_t expand_bytes = 0; | |
| 920 double free_percentage = ((double) free()) / capacity(); | |
| 921 double desired_free_percentage = (double) MinHeapFreeRatio / 100; | |
| 922 double maximum_free_percentage = (double) MaxHeapFreeRatio / 100; | |
| 923 | |
| 924 // compute expansion delta needed for reaching desired free percentage | |
| 925 if (free_percentage < desired_free_percentage) { | |
| 926 size_t desired_capacity = (size_t)(used() / ((double) 1 - desired_free_percentage)); | |
| 927 assert(desired_capacity >= capacity(), "invalid expansion size"); | |
| 928 expand_bytes = MAX2(desired_capacity - capacity(), MinHeapDeltaBytes); | |
| 929 } | |
| 930 if (expand_bytes > 0) { | |
| 931 if (PrintGCDetails && Verbose) { | |
| 932 size_t desired_capacity = (size_t)(used() / ((double) 1 - desired_free_percentage)); | |
| 933 gclog_or_tty->print_cr("\nFrom compute_new_size: "); | |
| 934 gclog_or_tty->print_cr(" Free fraction %f", free_percentage); | |
| 935 gclog_or_tty->print_cr(" Desired free fraction %f", | |
| 936 desired_free_percentage); | |
| 937 gclog_or_tty->print_cr(" Maximum free fraction %f", | |
| 938 maximum_free_percentage); | |
| 939 gclog_or_tty->print_cr(" Capactiy "SIZE_FORMAT, capacity()/1000); | |
| 940 gclog_or_tty->print_cr(" Desired capacity "SIZE_FORMAT, | |
| 941 desired_capacity/1000); | |
| 942 int prev_level = level() - 1; | |
| 943 if (prev_level >= 0) { | |
| 944 size_t prev_size = 0; | |
| 945 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 946 Generation* prev_gen = gch->_gens[prev_level]; | |
| 947 prev_size = prev_gen->capacity(); | |
| 948 gclog_or_tty->print_cr(" Younger gen size "SIZE_FORMAT, | |
| 949 prev_size/1000); | |
| 950 } | |
| 951 gclog_or_tty->print_cr(" unsafe_max_alloc_nogc "SIZE_FORMAT, | |
| 952 unsafe_max_alloc_nogc()/1000); | |
| 953 gclog_or_tty->print_cr(" contiguous available "SIZE_FORMAT, | |
| 954 contiguous_available()/1000); | |
| 955 gclog_or_tty->print_cr(" Expand by "SIZE_FORMAT" (bytes)", | |
| 956 expand_bytes); | |
| 957 } | |
| 958 // safe if expansion fails | |
| 959 expand(expand_bytes, 0, CMSExpansionCause::_satisfy_free_ratio); | |
| 960 if (PrintGCDetails && Verbose) { | |
| 961 gclog_or_tty->print_cr(" Expanded free fraction %f", | |
| 962 ((double) free()) / capacity()); | |
| 963 } | |
| 964 } | |
| 965 } | |
| 966 | |
| 967 Mutex* ConcurrentMarkSweepGeneration::freelistLock() const { | |
| 968 return cmsSpace()->freelistLock(); | |
| 969 } | |
| 970 | |
| 971 HeapWord* ConcurrentMarkSweepGeneration::allocate(size_t size, | |
| 972 bool tlab) { | |
| 973 CMSSynchronousYieldRequest yr; | |
| 974 MutexLockerEx x(freelistLock(), | |
| 975 Mutex::_no_safepoint_check_flag); | |
| 976 return have_lock_and_allocate(size, tlab); | |
| 977 } | |
| 978 | |
| 979 HeapWord* ConcurrentMarkSweepGeneration::have_lock_and_allocate(size_t size, | |
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980 bool tlab /* ignored */) { |
| 0 | 981 assert_lock_strong(freelistLock()); |
| 982 size_t adjustedSize = CompactibleFreeListSpace::adjustObjectSize(size); | |
| 983 HeapWord* res = cmsSpace()->allocate(adjustedSize); | |
| 984 // Allocate the object live (grey) if the background collector has | |
| 985 // started marking. This is necessary because the marker may | |
| 986 // have passed this address and consequently this object will | |
| 987 // not otherwise be greyed and would be incorrectly swept up. | |
| 988 // Note that if this object contains references, the writing | |
| 989 // of those references will dirty the card containing this object | |
| 990 // allowing the object to be blackened (and its references scanned) | |
| 991 // either during a preclean phase or at the final checkpoint. | |
| 992 if (res != NULL) { | |
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993 // We may block here with an uninitialized object with |
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994 // its mark-bit or P-bits not yet set. Such objects need |
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995 // to be safely navigable by block_start(). |
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996 assert(oop(res)->klass_or_null() == NULL, "Object should be uninitialized here."); |
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997 assert(!((FreeChunk*)res)->is_free(), "Error, block will look free but show wrong size"); |
| 0 | 998 collector()->direct_allocated(res, adjustedSize); |
| 999 _direct_allocated_words += adjustedSize; | |
| 1000 // allocation counters | |
| 1001 NOT_PRODUCT( | |
| 1002 _numObjectsAllocated++; | |
| 1003 _numWordsAllocated += (int)adjustedSize; | |
| 1004 ) | |
| 1005 } | |
| 1006 return res; | |
| 1007 } | |
| 1008 | |
| 1009 // In the case of direct allocation by mutators in a generation that | |
| 1010 // is being concurrently collected, the object must be allocated | |
| 1011 // live (grey) if the background collector has started marking. | |
| 1012 // This is necessary because the marker may | |
| 1013 // have passed this address and consequently this object will | |
| 1014 // not otherwise be greyed and would be incorrectly swept up. | |
| 1015 // Note that if this object contains references, the writing | |
| 1016 // of those references will dirty the card containing this object | |
| 1017 // allowing the object to be blackened (and its references scanned) | |
| 1018 // either during a preclean phase or at the final checkpoint. | |
| 1019 void CMSCollector::direct_allocated(HeapWord* start, size_t size) { | |
| 1020 assert(_markBitMap.covers(start, size), "Out of bounds"); | |
| 1021 if (_collectorState >= Marking) { | |
| 1022 MutexLockerEx y(_markBitMap.lock(), | |
| 1023 Mutex::_no_safepoint_check_flag); | |
| 1024 // [see comments preceding SweepClosure::do_blk() below for details] | |
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1025 // |
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1026 // Can the P-bits be deleted now? JJJ |
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1027 // |
| 0 | 1028 // 1. need to mark the object as live so it isn't collected |
| 1029 // 2. need to mark the 2nd bit to indicate the object may be uninitialized | |
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1030 // 3. need to mark the end of the object so marking, precleaning or sweeping |
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1031 // can skip over uninitialized or unparsable objects. An allocated |
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1032 // object is considered uninitialized for our purposes as long as |
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1033 // its klass word is NULL. All old gen objects are parsable |
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1034 // as soon as they are initialized.) |
| 0 | 1035 _markBitMap.mark(start); // object is live |
| 1036 _markBitMap.mark(start + 1); // object is potentially uninitialized? | |
| 1037 _markBitMap.mark(start + size - 1); | |
| 1038 // mark end of object | |
| 1039 } | |
| 1040 // check that oop looks uninitialized | |
| 187 | 1041 assert(oop(start)->klass_or_null() == NULL, "_klass should be NULL"); |
| 0 | 1042 } |
| 1043 | |
| 1044 void CMSCollector::promoted(bool par, HeapWord* start, | |
| 1045 bool is_obj_array, size_t obj_size) { | |
| 1046 assert(_markBitMap.covers(start), "Out of bounds"); | |
| 1047 // See comment in direct_allocated() about when objects should | |
| 1048 // be allocated live. | |
| 1049 if (_collectorState >= Marking) { | |
| 1050 // we already hold the marking bit map lock, taken in | |
| 1051 // the prologue | |
| 1052 if (par) { | |
| 1053 _markBitMap.par_mark(start); | |
| 1054 } else { | |
| 1055 _markBitMap.mark(start); | |
| 1056 } | |
| 1057 // We don't need to mark the object as uninitialized (as | |
| 1058 // in direct_allocated above) because this is being done with the | |
| 1059 // world stopped and the object will be initialized by the | |
|
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1060 // time the marking, precleaning or sweeping get to look at it. |
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1061 // But see the code for copying objects into the CMS generation, |
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1062 // where we need to ensure that concurrent readers of the |
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1063 // block offset table are able to safely navigate a block that |
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1064 // is in flux from being free to being allocated (and in |
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1065 // transition while being copied into) and subsequently |
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1066 // becoming a bona-fide object when the copy/promotion is complete. |
| 0 | 1067 assert(SafepointSynchronize::is_at_safepoint(), |
| 1068 "expect promotion only at safepoints"); | |
| 1069 | |
| 1070 if (_collectorState < Sweeping) { | |
| 1071 // Mark the appropriate cards in the modUnionTable, so that | |
| 1072 // this object gets scanned before the sweep. If this is | |
| 1073 // not done, CMS generation references in the object might | |
| 1074 // not get marked. | |
| 1075 // For the case of arrays, which are otherwise precisely | |
| 1076 // marked, we need to dirty the entire array, not just its head. | |
| 1077 if (is_obj_array) { | |
| 1078 // The [par_]mark_range() method expects mr.end() below to | |
| 1079 // be aligned to the granularity of a bit's representation | |
| 1080 // in the heap. In the case of the MUT below, that's a | |
| 1081 // card size. | |
| 1082 MemRegion mr(start, | |
| 1083 (HeapWord*)round_to((intptr_t)(start + obj_size), | |
| 1084 CardTableModRefBS::card_size /* bytes */)); | |
| 1085 if (par) { | |
| 1086 _modUnionTable.par_mark_range(mr); | |
| 1087 } else { | |
| 1088 _modUnionTable.mark_range(mr); | |
| 1089 } | |
| 1090 } else { // not an obj array; we can just mark the head | |
| 1091 if (par) { | |
| 1092 _modUnionTable.par_mark(start); | |
| 1093 } else { | |
| 1094 _modUnionTable.mark(start); | |
| 1095 } | |
| 1096 } | |
| 1097 } | |
| 1098 } | |
| 1099 } | |
| 1100 | |
| 1101 static inline size_t percent_of_space(Space* space, HeapWord* addr) | |
| 1102 { | |
| 1103 size_t delta = pointer_delta(addr, space->bottom()); | |
| 1104 return (size_t)(delta * 100.0 / (space->capacity() / HeapWordSize)); | |
| 1105 } | |
| 1106 | |
| 1107 void CMSCollector::icms_update_allocation_limits() | |
| 1108 { | |
| 1109 Generation* gen0 = GenCollectedHeap::heap()->get_gen(0); | |
| 1110 EdenSpace* eden = gen0->as_DefNewGeneration()->eden(); | |
| 1111 | |
| 1112 const unsigned int duty_cycle = stats().icms_update_duty_cycle(); | |
| 1113 if (CMSTraceIncrementalPacing) { | |
| 1114 stats().print(); | |
| 1115 } | |
| 1116 | |
| 1117 assert(duty_cycle <= 100, "invalid duty cycle"); | |
| 1118 if (duty_cycle != 0) { | |
| 1119 // The duty_cycle is a percentage between 0 and 100; convert to words and | |
| 1120 // then compute the offset from the endpoints of the space. | |
| 1121 size_t free_words = eden->free() / HeapWordSize; | |
| 1122 double free_words_dbl = (double)free_words; | |
| 1123 size_t duty_cycle_words = (size_t)(free_words_dbl * duty_cycle / 100.0); | |
| 1124 size_t offset_words = (free_words - duty_cycle_words) / 2; | |
| 1125 | |
| 1126 _icms_start_limit = eden->top() + offset_words; | |
| 1127 _icms_stop_limit = eden->end() - offset_words; | |
| 1128 | |
| 1129 // The limits may be adjusted (shifted to the right) by | |
| 1130 // CMSIncrementalOffset, to allow the application more mutator time after a | |
| 1131 // young gen gc (when all mutators were stopped) and before CMS starts and | |
| 1132 // takes away one or more cpus. | |
| 1133 if (CMSIncrementalOffset != 0) { | |
| 1134 double adjustment_dbl = free_words_dbl * CMSIncrementalOffset / 100.0; | |
| 1135 size_t adjustment = (size_t)adjustment_dbl; | |
| 1136 HeapWord* tmp_stop = _icms_stop_limit + adjustment; | |
| 1137 if (tmp_stop > _icms_stop_limit && tmp_stop < eden->end()) { | |
| 1138 _icms_start_limit += adjustment; | |
| 1139 _icms_stop_limit = tmp_stop; | |
| 1140 } | |
| 1141 } | |
| 1142 } | |
| 1143 if (duty_cycle == 0 || (_icms_start_limit == _icms_stop_limit)) { | |
| 1144 _icms_start_limit = _icms_stop_limit = eden->end(); | |
| 1145 } | |
| 1146 | |
| 1147 // Install the new start limit. | |
| 1148 eden->set_soft_end(_icms_start_limit); | |
| 1149 | |
| 1150 if (CMSTraceIncrementalMode) { | |
| 1151 gclog_or_tty->print(" icms alloc limits: " | |
| 1152 PTR_FORMAT "," PTR_FORMAT | |
| 1153 " (" SIZE_FORMAT "%%," SIZE_FORMAT "%%) ", | |
| 1154 _icms_start_limit, _icms_stop_limit, | |
| 1155 percent_of_space(eden, _icms_start_limit), | |
| 1156 percent_of_space(eden, _icms_stop_limit)); | |
| 1157 if (Verbose) { | |
| 1158 gclog_or_tty->print("eden: "); | |
| 1159 eden->print_on(gclog_or_tty); | |
| 1160 } | |
| 1161 } | |
| 1162 } | |
| 1163 | |
| 1164 // Any changes here should try to maintain the invariant | |
| 1165 // that if this method is called with _icms_start_limit | |
| 1166 // and _icms_stop_limit both NULL, then it should return NULL | |
| 1167 // and not notify the icms thread. | |
| 1168 HeapWord* | |
| 1169 CMSCollector::allocation_limit_reached(Space* space, HeapWord* top, | |
| 1170 size_t word_size) | |
| 1171 { | |
| 1172 // A start_limit equal to end() means the duty cycle is 0, so treat that as a | |
| 1173 // nop. | |
| 1174 if (CMSIncrementalMode && _icms_start_limit != space->end()) { | |
| 1175 if (top <= _icms_start_limit) { | |
| 1176 if (CMSTraceIncrementalMode) { | |
| 1177 space->print_on(gclog_or_tty); | |
| 1178 gclog_or_tty->stamp(); | |
| 1179 gclog_or_tty->print_cr(" start limit top=" PTR_FORMAT | |
| 1180 ", new limit=" PTR_FORMAT | |
| 1181 " (" SIZE_FORMAT "%%)", | |
| 1182 top, _icms_stop_limit, | |
| 1183 percent_of_space(space, _icms_stop_limit)); | |
| 1184 } | |
| 1185 ConcurrentMarkSweepThread::start_icms(); | |
| 1186 assert(top < _icms_stop_limit, "Tautology"); | |
| 1187 if (word_size < pointer_delta(_icms_stop_limit, top)) { | |
| 1188 return _icms_stop_limit; | |
| 1189 } | |
| 1190 | |
| 1191 // The allocation will cross both the _start and _stop limits, so do the | |
| 1192 // stop notification also and return end(). | |
| 1193 if (CMSTraceIncrementalMode) { | |
| 1194 space->print_on(gclog_or_tty); | |
| 1195 gclog_or_tty->stamp(); | |
| 1196 gclog_or_tty->print_cr(" +stop limit top=" PTR_FORMAT | |
| 1197 ", new limit=" PTR_FORMAT | |
| 1198 " (" SIZE_FORMAT "%%)", | |
| 1199 top, space->end(), | |
| 1200 percent_of_space(space, space->end())); | |
| 1201 } | |
| 1202 ConcurrentMarkSweepThread::stop_icms(); | |
| 1203 return space->end(); | |
| 1204 } | |
| 1205 | |
| 1206 if (top <= _icms_stop_limit) { | |
| 1207 if (CMSTraceIncrementalMode) { | |
| 1208 space->print_on(gclog_or_tty); | |
| 1209 gclog_or_tty->stamp(); | |
| 1210 gclog_or_tty->print_cr(" stop limit top=" PTR_FORMAT | |
| 1211 ", new limit=" PTR_FORMAT | |
| 1212 " (" SIZE_FORMAT "%%)", | |
| 1213 top, space->end(), | |
| 1214 percent_of_space(space, space->end())); | |
| 1215 } | |
| 1216 ConcurrentMarkSweepThread::stop_icms(); | |
| 1217 return space->end(); | |
| 1218 } | |
| 1219 | |
| 1220 if (CMSTraceIncrementalMode) { | |
| 1221 space->print_on(gclog_or_tty); | |
| 1222 gclog_or_tty->stamp(); | |
| 1223 gclog_or_tty->print_cr(" end limit top=" PTR_FORMAT | |
| 1224 ", new limit=" PTR_FORMAT, | |
| 1225 top, NULL); | |
| 1226 } | |
| 1227 } | |
| 1228 | |
| 1229 return NULL; | |
| 1230 } | |
| 1231 | |
|
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1232 oop ConcurrentMarkSweepGeneration::promote(oop obj, size_t obj_size) { |
| 0 | 1233 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in"); |
| 1234 // allocate, copy and if necessary update promoinfo -- | |
| 1235 // delegate to underlying space. | |
| 1236 assert_lock_strong(freelistLock()); | |
| 1237 | |
| 1238 #ifndef PRODUCT | |
| 1239 if (Universe::heap()->promotion_should_fail()) { | |
| 1240 return NULL; | |
| 1241 } | |
| 1242 #endif // #ifndef PRODUCT | |
| 1243 | |
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1244 oop res = _cmsSpace->promote(obj, obj_size); |
| 0 | 1245 if (res == NULL) { |
| 1246 // expand and retry | |
| 1247 size_t s = _cmsSpace->expansionSpaceRequired(obj_size); // HeapWords | |
| 1248 expand(s*HeapWordSize, MinHeapDeltaBytes, | |
| 1249 CMSExpansionCause::_satisfy_promotion); | |
| 1250 // Since there's currently no next generation, we don't try to promote | |
| 1251 // into a more senior generation. | |
| 1252 assert(next_gen() == NULL, "assumption, based upon which no attempt " | |
| 1253 "is made to pass on a possibly failing " | |
| 1254 "promotion to next generation"); | |
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1255 res = _cmsSpace->promote(obj, obj_size); |
| 0 | 1256 } |
| 1257 if (res != NULL) { | |
| 1258 // See comment in allocate() about when objects should | |
| 1259 // be allocated live. | |
| 1260 assert(obj->is_oop(), "Will dereference klass pointer below"); | |
| 1261 collector()->promoted(false, // Not parallel | |
| 1262 (HeapWord*)res, obj->is_objArray(), obj_size); | |
| 1263 // promotion counters | |
| 1264 NOT_PRODUCT( | |
| 1265 _numObjectsPromoted++; | |
| 1266 _numWordsPromoted += | |
| 1267 (int)(CompactibleFreeListSpace::adjustObjectSize(obj->size())); | |
| 1268 ) | |
| 1269 } | |
| 1270 return res; | |
| 1271 } | |
| 1272 | |
| 1273 | |
| 1274 HeapWord* | |
| 1275 ConcurrentMarkSweepGeneration::allocation_limit_reached(Space* space, | |
| 1276 HeapWord* top, | |
| 1277 size_t word_sz) | |
| 1278 { | |
| 1279 return collector()->allocation_limit_reached(space, top, word_sz); | |
| 1280 } | |
| 1281 | |
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1282 // IMPORTANT: Notes on object size recognition in CMS. |
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1283 // --------------------------------------------------- |
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1284 // A block of storage in the CMS generation is always in |
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1285 // one of three states. A free block (FREE), an allocated |
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1286 // object (OBJECT) whose size() method reports the correct size, |
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1287 // and an intermediate state (TRANSIENT) in which its size cannot |
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1288 // be accurately determined. |
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1289 // STATE IDENTIFICATION: (32 bit and 64 bit w/o COOPS) |
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1290 // ----------------------------------------------------- |
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1291 // FREE: klass_word & 1 == 1; mark_word holds block size |
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1292 // |
|
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1293 // OBJECT: klass_word installed; klass_word != 0 && klass_word & 1 == 0; |
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1294 // obj->size() computes correct size |
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1295 // |
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1296 // TRANSIENT: klass_word == 0; size is indeterminate until we become an OBJECT |
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1297 // |
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1298 // STATE IDENTIFICATION: (64 bit+COOPS) |
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1299 // ------------------------------------ |
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1300 // FREE: mark_word & CMS_FREE_BIT == 1; mark_word & ~CMS_FREE_BIT gives block_size |
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1301 // |
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1302 // OBJECT: klass_word installed; klass_word != 0; |
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1303 // obj->size() computes correct size |
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1304 // |
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1305 // TRANSIENT: klass_word == 0; size is indeterminate until we become an OBJECT |
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1306 // |
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1307 // |
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1308 // STATE TRANSITION DIAGRAM |
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1309 // |
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1310 // mut / parnew mut / parnew |
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1311 // FREE --------------------> TRANSIENT ---------------------> OBJECT --| |
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1312 // ^ | |
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1313 // |------------------------ DEAD <------------------------------------| |
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1314 // sweep mut |
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1315 // |
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1316 // While a block is in TRANSIENT state its size cannot be determined |
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1317 // so readers will either need to come back later or stall until |
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1318 // the size can be determined. Note that for the case of direct |
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1319 // allocation, P-bits, when available, may be used to determine the |
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1320 // size of an object that may not yet have been initialized. |
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1321 |
| 0 | 1322 // Things to support parallel young-gen collection. |
| 1323 oop | |
| 1324 ConcurrentMarkSweepGeneration::par_promote(int thread_num, | |
| 1325 oop old, markOop m, | |
| 1326 size_t word_sz) { | |
| 1327 #ifndef PRODUCT | |
| 1328 if (Universe::heap()->promotion_should_fail()) { | |
| 1329 return NULL; | |
| 1330 } | |
| 1331 #endif // #ifndef PRODUCT | |
| 1332 | |
| 1333 CMSParGCThreadState* ps = _par_gc_thread_states[thread_num]; | |
| 1334 PromotionInfo* promoInfo = &ps->promo; | |
| 1335 // if we are tracking promotions, then first ensure space for | |
| 1336 // promotion (including spooling space for saving header if necessary). | |
| 1337 // then allocate and copy, then track promoted info if needed. | |
| 1338 // When tracking (see PromotionInfo::track()), the mark word may | |
| 1339 // be displaced and in this case restoration of the mark word | |
| 1340 // occurs in the (oop_since_save_marks_)iterate phase. | |
| 1341 if (promoInfo->tracking() && !promoInfo->ensure_spooling_space()) { | |
| 1342 // Out of space for allocating spooling buffers; | |
| 1343 // try expanding and allocating spooling buffers. | |
| 1344 if (!expand_and_ensure_spooling_space(promoInfo)) { | |
| 1345 return NULL; | |
| 1346 } | |
| 1347 } | |
| 1348 assert(promoInfo->has_spooling_space(), "Control point invariant"); | |
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1349 const size_t alloc_sz = CompactibleFreeListSpace::adjustObjectSize(word_sz); |
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1350 HeapWord* obj_ptr = ps->lab.alloc(alloc_sz); |
| 0 | 1351 if (obj_ptr == NULL) { |
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1352 obj_ptr = expand_and_par_lab_allocate(ps, alloc_sz); |
| 0 | 1353 if (obj_ptr == NULL) { |
| 1354 return NULL; | |
| 1355 } | |
| 1356 } | |
| 1357 oop obj = oop(obj_ptr); | |
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1358 OrderAccess::storestore(); |
| 187 | 1359 assert(obj->klass_or_null() == NULL, "Object should be uninitialized here."); |
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1360 assert(!((FreeChunk*)obj_ptr)->is_free(), "Error, block will look free but show wrong size"); |
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1361 // IMPORTANT: See note on object initialization for CMS above. |
| 0 | 1362 // Otherwise, copy the object. Here we must be careful to insert the |
| 1363 // klass pointer last, since this marks the block as an allocated object. | |
| 187 | 1364 // Except with compressed oops it's the mark word. |
| 0 | 1365 HeapWord* old_ptr = (HeapWord*)old; |
|
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1366 // Restore the mark word copied above. |
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1367 obj->set_mark(m); |
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1368 assert(obj->klass_or_null() == NULL, "Object should be uninitialized here."); |
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1369 assert(!((FreeChunk*)obj_ptr)->is_free(), "Error, block will look free but show wrong size"); |
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1370 OrderAccess::storestore(); |
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1371 |
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1372 if (UseCompressedKlassPointers) { |
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1373 // Copy gap missed by (aligned) header size calculation below |
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1374 obj->set_klass_gap(old->klass_gap()); |
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1375 } |
| 0 | 1376 if (word_sz > (size_t)oopDesc::header_size()) { |
| 1377 Copy::aligned_disjoint_words(old_ptr + oopDesc::header_size(), | |
| 1378 obj_ptr + oopDesc::header_size(), | |
| 1379 word_sz - oopDesc::header_size()); | |
| 1380 } | |
| 187 | 1381 |
| 0 | 1382 // Now we can track the promoted object, if necessary. We take care |
| 1521 | 1383 // to delay the transition from uninitialized to full object |
| 0 | 1384 // (i.e., insertion of klass pointer) until after, so that it |
| 1385 // atomically becomes a promoted object. | |
| 1386 if (promoInfo->tracking()) { | |
| 1387 promoInfo->track((PromotedObject*)obj, old->klass()); | |
| 1388 } | |
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1389 assert(obj->klass_or_null() == NULL, "Object should be uninitialized here."); |
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1390 assert(!((FreeChunk*)obj_ptr)->is_free(), "Error, block will look free but show wrong size"); |
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1391 assert(old->is_oop(), "Will use and dereference old klass ptr below"); |
| 187 | 1392 |
| 1393 // Finally, install the klass pointer (this should be volatile). | |
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1394 OrderAccess::storestore(); |
| 0 | 1395 obj->set_klass(old->klass()); |
|
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1396 // We should now be able to calculate the right size for this object |
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1397 assert(obj->is_oop() && obj->size() == (int)word_sz, "Error, incorrect size computed for promoted object"); |
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1398 |
| 0 | 1399 collector()->promoted(true, // parallel |
| 1400 obj_ptr, old->is_objArray(), word_sz); | |
| 1401 | |
| 1402 NOT_PRODUCT( | |
|
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1403 Atomic::inc_ptr(&_numObjectsPromoted); |
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1404 Atomic::add_ptr(alloc_sz, &_numWordsPromoted); |
| 0 | 1405 ) |
| 1406 | |
| 1407 return obj; | |
| 1408 } | |
| 1409 | |
| 1410 void | |
| 1411 ConcurrentMarkSweepGeneration:: | |
| 1412 par_promote_alloc_undo(int thread_num, | |
| 1413 HeapWord* obj, size_t word_sz) { | |
| 1414 // CMS does not support promotion undo. | |
| 1415 ShouldNotReachHere(); | |
| 1416 } | |
| 1417 | |
| 1418 void | |
| 1419 ConcurrentMarkSweepGeneration:: | |
| 1420 par_promote_alloc_done(int thread_num) { | |
| 1421 CMSParGCThreadState* ps = _par_gc_thread_states[thread_num]; | |
|
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1422 ps->lab.retire(thread_num); |
| 0 | 1423 } |
| 1424 | |
| 1425 void | |
| 1426 ConcurrentMarkSweepGeneration:: | |
| 1427 par_oop_since_save_marks_iterate_done(int thread_num) { | |
| 1428 CMSParGCThreadState* ps = _par_gc_thread_states[thread_num]; | |
| 1429 ParScanWithoutBarrierClosure* dummy_cl = NULL; | |
| 1430 ps->promo.promoted_oops_iterate_nv(dummy_cl); | |
| 1431 } | |
| 1432 | |
| 1433 bool ConcurrentMarkSweepGeneration::should_collect(bool full, | |
| 1434 size_t size, | |
| 1435 bool tlab) | |
| 1436 { | |
| 1437 // We allow a STW collection only if a full | |
| 1438 // collection was requested. | |
| 1439 return full || should_allocate(size, tlab); // FIX ME !!! | |
| 1440 // This and promotion failure handling are connected at the | |
| 1441 // hip and should be fixed by untying them. | |
| 1442 } | |
| 1443 | |
| 1444 bool CMSCollector::shouldConcurrentCollect() { | |
| 1445 if (_full_gc_requested) { | |
| 1446 if (Verbose && PrintGCDetails) { | |
| 1447 gclog_or_tty->print_cr("CMSCollector: collect because of explicit " | |
|
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1448 " gc request (or gc_locker)"); |
| 0 | 1449 } |
| 1450 return true; | |
| 1451 } | |
| 1452 | |
| 1453 // For debugging purposes, change the type of collection. | |
| 1454 // If the rotation is not on the concurrent collection | |
| 1455 // type, don't start a concurrent collection. | |
| 1456 NOT_PRODUCT( | |
| 1457 if (RotateCMSCollectionTypes && | |
| 1458 (_cmsGen->debug_collection_type() != | |
| 1459 ConcurrentMarkSweepGeneration::Concurrent_collection_type)) { | |
| 1460 assert(_cmsGen->debug_collection_type() != | |
| 1461 ConcurrentMarkSweepGeneration::Unknown_collection_type, | |
| 1462 "Bad cms collection type"); | |
| 1463 return false; | |
| 1464 } | |
| 1465 ) | |
| 1466 | |
| 1467 FreelistLocker x(this); | |
| 1468 // ------------------------------------------------------------------ | |
| 1469 // Print out lots of information which affects the initiation of | |
| 1470 // a collection. | |
| 1471 if (PrintCMSInitiationStatistics && stats().valid()) { | |
| 1472 gclog_or_tty->print("CMSCollector shouldConcurrentCollect: "); | |
| 1473 gclog_or_tty->stamp(); | |
| 1474 gclog_or_tty->print_cr(""); | |
| 1475 stats().print_on(gclog_or_tty); | |
| 1476 gclog_or_tty->print_cr("time_until_cms_gen_full %3.7f", | |
| 1477 stats().time_until_cms_gen_full()); | |
| 1478 gclog_or_tty->print_cr("free="SIZE_FORMAT, _cmsGen->free()); | |
| 1479 gclog_or_tty->print_cr("contiguous_available="SIZE_FORMAT, | |
| 1480 _cmsGen->contiguous_available()); | |
| 1481 gclog_or_tty->print_cr("promotion_rate=%g", stats().promotion_rate()); | |
| 1482 gclog_or_tty->print_cr("cms_allocation_rate=%g", stats().cms_allocation_rate()); | |
| 1483 gclog_or_tty->print_cr("occupancy=%3.7f", _cmsGen->occupancy()); | |
|
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1484 gclog_or_tty->print_cr("initiatingOccupancy=%3.7f", _cmsGen->initiating_occupancy()); |
|
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1485 gclog_or_tty->print_cr("metadata initialized %d", |
|
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1486 MetaspaceGC::should_concurrent_collect()); |
| 0 | 1487 } |
| 1488 // ------------------------------------------------------------------ | |
| 1489 | |
| 1490 // If the estimated time to complete a cms collection (cms_duration()) | |
| 1491 // is less than the estimated time remaining until the cms generation | |
| 1492 // is full, start a collection. | |
| 1493 if (!UseCMSInitiatingOccupancyOnly) { | |
| 1494 if (stats().valid()) { | |
| 1495 if (stats().time_until_cms_start() == 0.0) { | |
| 1496 return true; | |
| 1497 } | |
| 1498 } else { | |
| 1499 // We want to conservatively collect somewhat early in order | |
| 1500 // to try and "bootstrap" our CMS/promotion statistics; | |
| 1501 // this branch will not fire after the first successful CMS | |
| 1502 // collection because the stats should then be valid. | |
| 1503 if (_cmsGen->occupancy() >= _bootstrap_occupancy) { | |
| 1504 if (Verbose && PrintGCDetails) { | |
| 1505 gclog_or_tty->print_cr( | |
| 1506 " CMSCollector: collect for bootstrapping statistics:" | |
| 1507 " occupancy = %f, boot occupancy = %f", _cmsGen->occupancy(), | |
| 1508 _bootstrap_occupancy); | |
| 1509 } | |
| 1510 return true; | |
| 1511 } | |
| 1512 } | |
| 1513 } | |
| 1514 | |
|
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1515 // Otherwise, we start a collection cycle if |
| 0 | 1516 // old gen want a collection cycle started. Each may use |
| 1517 // an appropriate criterion for making this decision. | |
| 1518 // XXX We need to make sure that the gen expansion | |
|
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1519 // criterion dovetails well with this. XXX NEED TO FIX THIS |
|
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|
1520 if (_cmsGen->should_concurrent_collect()) { |
| 0 | 1521 if (Verbose && PrintGCDetails) { |
| 1522 gclog_or_tty->print_cr("CMS old gen initiated"); | |
| 1523 } | |
| 1524 return true; | |
| 1525 } | |
| 1526 | |
|
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|
1527 // We start a collection if we believe an incremental collection may fail; |
|
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1528 // this is not likely to be productive in practice because it's probably too |
|
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1529 // late anyway. |
|
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|
1530 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
|
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1531 assert(gch->collector_policy()->is_two_generation_policy(), |
|
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1532 "You may want to check the correctness of the following"); |
|
1994
6cd6d394f280
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|
1533 if (gch->incremental_collection_will_fail(true /* consult_young */)) { |
|
6cd6d394f280
7001033: assert(gch->gc_cause() == GCCause::_scavenge_alot || !gch->incremental_collection_failed())
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diff
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|
1534 if (Verbose && PrintGCDetails) { |
|
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|
1535 gclog_or_tty->print("CMSCollector: collect because incremental collection will fail "); |
| 0 | 1536 } |
| 1537 return true; | |
| 1538 } | |
| 1539 | |
|
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1540 if (MetaspaceGC::should_concurrent_collect()) { |
|
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1541 if (Verbose && PrintGCDetails) { |
|
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1542 gclog_or_tty->print("CMSCollector: collect for metadata allocation "); |
|
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1543 } |
|
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1544 return true; |
|
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|
1545 } |
|
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|
1546 |
| 0 | 1547 return false; |
| 1548 } | |
| 1549 | |
| 1550 // Clear _expansion_cause fields of constituent generations | |
| 1551 void CMSCollector::clear_expansion_cause() { | |
| 1552 _cmsGen->clear_expansion_cause(); | |
| 1553 } | |
| 1554 | |
|
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1555 // We should be conservative in starting a collection cycle. To |
|
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|
1556 // start too eagerly runs the risk of collecting too often in the |
|
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|
1557 // extreme. To collect too rarely falls back on full collections, |
|
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|
1558 // which works, even if not optimum in terms of concurrent work. |
|
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|
1559 // As a work around for too eagerly collecting, use the flag |
|
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|
1560 // UseCMSInitiatingOccupancyOnly. This also has the advantage of |
|
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|
1561 // giving the user an easily understandable way of controlling the |
|
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|
1562 // collections. |
|
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|
1563 // We want to start a new collection cycle if any of the following |
|
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|
1564 // conditions hold: |
|
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1565 // . our current occupancy exceeds the configured initiating occupancy |
|
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|
1566 // for this generation, or |
|
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|
1567 // . we recently needed to expand this space and have not, since that |
|
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|
1568 // expansion, done a collection of this generation, or |
|
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|
1569 // . the underlying space believes that it may be a good idea to initiate |
|
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|
1570 // a concurrent collection (this may be based on criteria such as the |
|
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|
1571 // following: the space uses linear allocation and linear allocation is |
|
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|
1572 // going to fail, or there is believed to be excessive fragmentation in |
|
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|
1573 // the generation, etc... or ... |
|
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|
1574 // [.(currently done by CMSCollector::shouldConcurrentCollect() only for |
|
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1575 // the case of the old generation; see CR 6543076): |
|
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1576 // we may be approaching a point at which allocation requests may fail because |
|
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|
1577 // we will be out of sufficient free space given allocation rate estimates.] |
|
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|
1578 bool ConcurrentMarkSweepGeneration::should_concurrent_collect() const { |
|
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1579 |
| 0 | 1580 assert_lock_strong(freelistLock()); |
|
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1581 if (occupancy() > initiating_occupancy()) { |
| 0 | 1582 if (PrintGCDetails && Verbose) { |
| 1583 gclog_or_tty->print(" %s: collect because of occupancy %f / %f ", | |
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1584 short_name(), occupancy(), initiating_occupancy()); |
| 0 | 1585 } |
| 1586 return true; | |
| 1587 } | |
| 1588 if (UseCMSInitiatingOccupancyOnly) { | |
| 1589 return false; | |
| 1590 } | |
| 1591 if (expansion_cause() == CMSExpansionCause::_satisfy_allocation) { | |
| 1592 if (PrintGCDetails && Verbose) { | |
| 1593 gclog_or_tty->print(" %s: collect because expanded for allocation ", | |
| 1594 short_name()); | |
| 1595 } | |
| 1596 return true; | |
| 1597 } | |
|
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1598 if (_cmsSpace->should_concurrent_collect()) { |
| 0 | 1599 if (PrintGCDetails && Verbose) { |
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1600 gclog_or_tty->print(" %s: collect because cmsSpace says so ", |
| 0 | 1601 short_name()); |
| 1602 } | |
| 1603 return true; | |
| 1604 } | |
| 1605 return false; | |
| 1606 } | |
| 1607 | |
| 1608 void ConcurrentMarkSweepGeneration::collect(bool full, | |
| 1609 bool clear_all_soft_refs, | |
| 1610 size_t size, | |
| 1611 bool tlab) | |
| 1612 { | |
| 1613 collector()->collect(full, clear_all_soft_refs, size, tlab); | |
| 1614 } | |
| 1615 | |
| 1616 void CMSCollector::collect(bool full, | |
| 1617 bool clear_all_soft_refs, | |
| 1618 size_t size, | |
| 1619 bool tlab) | |
| 1620 { | |
| 1621 if (!UseCMSCollectionPassing && _collectorState > Idling) { | |
| 1622 // For debugging purposes skip the collection if the state | |
| 1623 // is not currently idle | |
| 1624 if (TraceCMSState) { | |
| 1625 gclog_or_tty->print_cr("Thread " INTPTR_FORMAT " skipped full:%d CMS state %d", | |
| 1626 Thread::current(), full, _collectorState); | |
| 1627 } | |
| 1628 return; | |
| 1629 } | |
| 1630 | |
| 1631 // The following "if" branch is present for defensive reasons. | |
| 1632 // In the current uses of this interface, it can be replaced with: | |
| 1633 // assert(!GC_locker.is_active(), "Can't be called otherwise"); | |
| 1634 // But I am not placing that assert here to allow future | |
| 1635 // generality in invoking this interface. | |
| 1636 if (GC_locker::is_active()) { | |
| 1637 // A consistency test for GC_locker | |
| 1638 assert(GC_locker::needs_gc(), "Should have been set already"); | |
| 1639 // Skip this foreground collection, instead | |
| 1640 // expanding the heap if necessary. | |
| 1641 // Need the free list locks for the call to free() in compute_new_size() | |
| 1642 compute_new_size(); | |
| 1643 return; | |
| 1644 } | |
| 1645 acquire_control_and_collect(full, clear_all_soft_refs); | |
| 1646 _full_gcs_since_conc_gc++; | |
| 1647 | |
| 1648 } | |
| 1649 | |
| 1650 void CMSCollector::request_full_gc(unsigned int full_gc_count) { | |
| 1651 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 1652 unsigned int gc_count = gch->total_full_collections(); | |
| 1653 if (gc_count == full_gc_count) { | |
| 1654 MutexLockerEx y(CGC_lock, Mutex::_no_safepoint_check_flag); | |
| 1655 _full_gc_requested = true; | |
| 1656 CGC_lock->notify(); // nudge CMS thread | |
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1657 } else { |
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1658 assert(gc_count > full_gc_count, "Error: causal loop"); |
| 0 | 1659 } |
| 1660 } | |
| 1661 | |
| 1662 | |
| 1663 // The foreground and background collectors need to coordinate in order | |
| 1664 // to make sure that they do not mutually interfere with CMS collections. | |
| 1665 // When a background collection is active, | |
| 1666 // the foreground collector may need to take over (preempt) and | |
| 1667 // synchronously complete an ongoing collection. Depending on the | |
| 1668 // frequency of the background collections and the heap usage | |
| 1669 // of the application, this preemption can be seldom or frequent. | |
| 1670 // There are only certain | |
| 1671 // points in the background collection that the "collection-baton" | |
| 1672 // can be passed to the foreground collector. | |
| 1673 // | |
| 1674 // The foreground collector will wait for the baton before | |
| 1675 // starting any part of the collection. The foreground collector | |
| 1676 // will only wait at one location. | |
| 1677 // | |
| 1678 // The background collector will yield the baton before starting a new | |
| 1679 // phase of the collection (e.g., before initial marking, marking from roots, | |
| 1680 // precleaning, final re-mark, sweep etc.) This is normally done at the head | |
| 1681 // of the loop which switches the phases. The background collector does some | |
| 1682 // of the phases (initial mark, final re-mark) with the world stopped. | |
| 1683 // Because of locking involved in stopping the world, | |
| 1684 // the foreground collector should not block waiting for the background | |
| 1685 // collector when it is doing a stop-the-world phase. The background | |
| 1686 // collector will yield the baton at an additional point just before | |
| 1687 // it enters a stop-the-world phase. Once the world is stopped, the | |
| 1688 // background collector checks the phase of the collection. If the | |
| 1689 // phase has not changed, it proceeds with the collection. If the | |
| 1690 // phase has changed, it skips that phase of the collection. See | |
| 1691 // the comments on the use of the Heap_lock in collect_in_background(). | |
| 1692 // | |
| 1693 // Variable used in baton passing. | |
| 1694 // _foregroundGCIsActive - Set to true by the foreground collector when | |
| 1695 // it wants the baton. The foreground clears it when it has finished | |
| 1696 // the collection. | |
| 1697 // _foregroundGCShouldWait - Set to true by the background collector | |
| 1698 // when it is running. The foreground collector waits while | |
| 1699 // _foregroundGCShouldWait is true. | |
| 1700 // CGC_lock - monitor used to protect access to the above variables | |
| 1701 // and to notify the foreground and background collectors. | |
| 1702 // _collectorState - current state of the CMS collection. | |
| 1703 // | |
| 1704 // The foreground collector | |
| 1705 // acquires the CGC_lock | |
| 1706 // sets _foregroundGCIsActive | |
| 1707 // waits on the CGC_lock for _foregroundGCShouldWait to be false | |
| 1708 // various locks acquired in preparation for the collection | |
| 1709 // are released so as not to block the background collector | |
| 1710 // that is in the midst of a collection | |
| 1711 // proceeds with the collection | |
| 1712 // clears _foregroundGCIsActive | |
| 1713 // returns | |
| 1714 // | |
| 1715 // The background collector in a loop iterating on the phases of the | |
| 1716 // collection | |
| 1717 // acquires the CGC_lock | |
| 1718 // sets _foregroundGCShouldWait | |
| 1719 // if _foregroundGCIsActive is set | |
| 1720 // clears _foregroundGCShouldWait, notifies _CGC_lock | |
| 1721 // waits on _CGC_lock for _foregroundGCIsActive to become false | |
| 1722 // and exits the loop. | |
| 1723 // otherwise | |
| 1724 // proceed with that phase of the collection | |
| 1725 // if the phase is a stop-the-world phase, | |
| 1726 // yield the baton once more just before enqueueing | |
| 1727 // the stop-world CMS operation (executed by the VM thread). | |
| 1728 // returns after all phases of the collection are done | |
| 1729 // | |
| 1730 | |
| 1731 void CMSCollector::acquire_control_and_collect(bool full, | |
| 1732 bool clear_all_soft_refs) { | |
| 1733 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); | |
| 1734 assert(!Thread::current()->is_ConcurrentGC_thread(), | |
| 1735 "shouldn't try to acquire control from self!"); | |
| 1736 | |
| 1737 // Start the protocol for acquiring control of the | |
| 1738 // collection from the background collector (aka CMS thread). | |
| 1739 assert(ConcurrentMarkSweepThread::vm_thread_has_cms_token(), | |
| 1740 "VM thread should have CMS token"); | |
| 1741 // Remember the possibly interrupted state of an ongoing | |
| 1742 // concurrent collection | |
| 1743 CollectorState first_state = _collectorState; | |
| 1744 | |
| 1745 // Signal to a possibly ongoing concurrent collection that | |
| 1746 // we want to do a foreground collection. | |
| 1747 _foregroundGCIsActive = true; | |
| 1748 | |
| 1749 // Disable incremental mode during a foreground collection. | |
| 1750 ICMSDisabler icms_disabler; | |
| 1751 | |
| 1752 // release locks and wait for a notify from the background collector | |
| 1753 // releasing the locks in only necessary for phases which | |
| 1754 // do yields to improve the granularity of the collection. | |
| 1755 assert_lock_strong(bitMapLock()); | |
| 1756 // We need to lock the Free list lock for the space that we are | |
| 1757 // currently collecting. | |
| 1758 assert(haveFreelistLocks(), "Must be holding free list locks"); | |
| 1759 bitMapLock()->unlock(); | |
| 1760 releaseFreelistLocks(); | |
| 1761 { | |
| 1762 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
| 1763 if (_foregroundGCShouldWait) { | |
| 1764 // We are going to be waiting for action for the CMS thread; | |
| 1765 // it had better not be gone (for instance at shutdown)! | |
| 1766 assert(ConcurrentMarkSweepThread::cmst() != NULL, | |
| 1767 "CMS thread must be running"); | |
| 1768 // Wait here until the background collector gives us the go-ahead | |
| 1769 ConcurrentMarkSweepThread::clear_CMS_flag( | |
| 1770 ConcurrentMarkSweepThread::CMS_vm_has_token); // release token | |
| 1771 // Get a possibly blocked CMS thread going: | |
| 1772 // Note that we set _foregroundGCIsActive true above, | |
| 1773 // without protection of the CGC_lock. | |
| 1774 CGC_lock->notify(); | |
| 1775 assert(!ConcurrentMarkSweepThread::vm_thread_wants_cms_token(), | |
| 1776 "Possible deadlock"); | |
| 1777 while (_foregroundGCShouldWait) { | |
| 1778 // wait for notification | |
| 1779 CGC_lock->wait(Mutex::_no_safepoint_check_flag); | |
| 1780 // Possibility of delay/starvation here, since CMS token does | |
| 1781 // not know to give priority to VM thread? Actually, i think | |
| 1782 // there wouldn't be any delay/starvation, but the proof of | |
| 1783 // that "fact" (?) appears non-trivial. XXX 20011219YSR | |
| 1784 } | |
| 1785 ConcurrentMarkSweepThread::set_CMS_flag( | |
| 1786 ConcurrentMarkSweepThread::CMS_vm_has_token); | |
| 1787 } | |
| 1788 } | |
| 1789 // The CMS_token is already held. Get back the other locks. | |
| 1790 assert(ConcurrentMarkSweepThread::vm_thread_has_cms_token(), | |
| 1791 "VM thread should have CMS token"); | |
| 1792 getFreelistLocks(); | |
| 1793 bitMapLock()->lock_without_safepoint_check(); | |
| 1794 if (TraceCMSState) { | |
| 1795 gclog_or_tty->print_cr("CMS foreground collector has asked for control " | |
| 1796 INTPTR_FORMAT " with first state %d", Thread::current(), first_state); | |
| 1797 gclog_or_tty->print_cr(" gets control with state %d", _collectorState); | |
| 1798 } | |
| 1799 | |
| 1800 // Check if we need to do a compaction, or if not, whether | |
| 1801 // we need to start the mark-sweep from scratch. | |
| 1802 bool should_compact = false; | |
| 1803 bool should_start_over = false; | |
| 1804 decide_foreground_collection_type(clear_all_soft_refs, | |
| 1805 &should_compact, &should_start_over); | |
| 1806 | |
| 1807 NOT_PRODUCT( | |
| 1808 if (RotateCMSCollectionTypes) { | |
| 1809 if (_cmsGen->debug_collection_type() == | |
| 1810 ConcurrentMarkSweepGeneration::MSC_foreground_collection_type) { | |
| 1811 should_compact = true; | |
| 1812 } else if (_cmsGen->debug_collection_type() == | |
| 1813 ConcurrentMarkSweepGeneration::MS_foreground_collection_type) { | |
| 1814 should_compact = false; | |
| 1815 } | |
| 1816 } | |
| 1817 ) | |
| 1818 | |
| 1819 if (PrintGCDetails && first_state > Idling) { | |
| 1820 GCCause::Cause cause = GenCollectedHeap::heap()->gc_cause(); | |
| 1821 if (GCCause::is_user_requested_gc(cause) || | |
| 1822 GCCause::is_serviceability_requested_gc(cause)) { | |
| 1823 gclog_or_tty->print(" (concurrent mode interrupted)"); | |
| 1824 } else { | |
| 1825 gclog_or_tty->print(" (concurrent mode failure)"); | |
| 1826 } | |
| 1827 } | |
| 1828 | |
| 1829 if (should_compact) { | |
| 1830 // If the collection is being acquired from the background | |
| 1831 // collector, there may be references on the discovered | |
| 1832 // references lists that have NULL referents (being those | |
| 1833 // that were concurrently cleared by a mutator) or | |
| 1834 // that are no longer active (having been enqueued concurrently | |
| 1835 // by the mutator). | |
| 1836 // Scrub the list of those references because Mark-Sweep-Compact | |
| 1837 // code assumes referents are not NULL and that all discovered | |
| 1838 // Reference objects are active. | |
| 1839 ref_processor()->clean_up_discovered_references(); | |
| 1840 | |
| 1841 do_compaction_work(clear_all_soft_refs); | |
| 1842 | |
| 1843 // Has the GC time limit been exceeded? | |
|
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1844 DefNewGeneration* young_gen = _young_gen->as_DefNewGeneration(); |
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1845 size_t max_eden_size = young_gen->max_capacity() - |
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1846 young_gen->to()->capacity() - |
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1847 young_gen->from()->capacity(); |
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1848 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
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1849 GCCause::Cause gc_cause = gch->gc_cause(); |
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1850 size_policy()->check_gc_overhead_limit(_young_gen->used(), |
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1851 young_gen->eden()->used(), |
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1852 _cmsGen->max_capacity(), |
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1853 max_eden_size, |
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1854 full, |
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1855 gc_cause, |
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1856 gch->collector_policy()); |
| 0 | 1857 } else { |
| 1858 do_mark_sweep_work(clear_all_soft_refs, first_state, | |
| 1859 should_start_over); | |
| 1860 } | |
| 1861 // Reset the expansion cause, now that we just completed | |
| 1862 // a collection cycle. | |
| 1863 clear_expansion_cause(); | |
| 1864 _foregroundGCIsActive = false; | |
| 1865 return; | |
| 1866 } | |
| 1867 | |
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1868 // Resize the tenured generation |
| 0 | 1869 // after obtaining the free list locks for the |
| 1870 // two generations. | |
| 1871 void CMSCollector::compute_new_size() { | |
| 1872 assert_locked_or_safepoint(Heap_lock); | |
| 1873 FreelistLocker z(this); | |
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1874 MetaspaceGC::compute_new_size(); |
| 0 | 1875 _cmsGen->compute_new_size(); |
| 1876 } | |
| 1877 | |
| 1878 // A work method used by foreground collection to determine | |
| 1879 // what type of collection (compacting or not, continuing or fresh) | |
| 1880 // it should do. | |
| 1881 // NOTE: the intent is to make UseCMSCompactAtFullCollection | |
| 1882 // and CMSCompactWhenClearAllSoftRefs the default in the future | |
| 1883 // and do away with the flags after a suitable period. | |
| 1884 void CMSCollector::decide_foreground_collection_type( | |
| 1885 bool clear_all_soft_refs, bool* should_compact, | |
| 1886 bool* should_start_over) { | |
| 1887 // Normally, we'll compact only if the UseCMSCompactAtFullCollection | |
| 1888 // flag is set, and we have either requested a System.gc() or | |
| 1889 // the number of full gc's since the last concurrent cycle | |
| 1890 // has exceeded the threshold set by CMSFullGCsBeforeCompaction, | |
| 1891 // or if an incremental collection has failed | |
| 1892 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 1893 assert(gch->collector_policy()->is_two_generation_policy(), | |
| 1894 "You may want to check the correctness of the following"); | |
| 1895 // Inform cms gen if this was due to partial collection failing. | |
| 1896 // The CMS gen may use this fact to determine its expansion policy. | |
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1897 if (gch->incremental_collection_will_fail(false /* don't consult_young */)) { |
| 0 | 1898 assert(!_cmsGen->incremental_collection_failed(), |
| 1899 "Should have been noticed, reacted to and cleared"); | |
| 1900 _cmsGen->set_incremental_collection_failed(); | |
| 1901 } | |
| 1902 *should_compact = | |
| 1903 UseCMSCompactAtFullCollection && | |
| 1904 ((_full_gcs_since_conc_gc >= CMSFullGCsBeforeCompaction) || | |
| 1905 GCCause::is_user_requested_gc(gch->gc_cause()) || | |
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1906 gch->incremental_collection_will_fail(true /* consult_young */)); |
| 0 | 1907 *should_start_over = false; |
| 1908 if (clear_all_soft_refs && !*should_compact) { | |
| 1909 // We are about to do a last ditch collection attempt | |
| 1910 // so it would normally make sense to do a compaction | |
| 1911 // to reclaim as much space as possible. | |
| 1912 if (CMSCompactWhenClearAllSoftRefs) { | |
| 1913 // Default: The rationale is that in this case either | |
| 1914 // we are past the final marking phase, in which case | |
| 1915 // we'd have to start over, or so little has been done | |
| 1916 // that there's little point in saving that work. Compaction | |
| 1917 // appears to be the sensible choice in either case. | |
| 1918 *should_compact = true; | |
| 1919 } else { | |
| 1920 // We have been asked to clear all soft refs, but not to | |
| 1921 // compact. Make sure that we aren't past the final checkpoint | |
| 1922 // phase, for that is where we process soft refs. If we are already | |
| 1923 // past that phase, we'll need to redo the refs discovery phase and | |
| 1924 // if necessary clear soft refs that weren't previously | |
| 1925 // cleared. We do so by remembering the phase in which | |
| 1926 // we came in, and if we are past the refs processing | |
| 1927 // phase, we'll choose to just redo the mark-sweep | |
| 1928 // collection from scratch. | |
| 1929 if (_collectorState > FinalMarking) { | |
| 1930 // We are past the refs processing phase; | |
| 1931 // start over and do a fresh synchronous CMS cycle | |
| 1932 _collectorState = Resetting; // skip to reset to start new cycle | |
| 1933 reset(false /* == !asynch */); | |
| 1934 *should_start_over = true; | |
| 1935 } // else we can continue a possibly ongoing current cycle | |
| 1936 } | |
| 1937 } | |
| 1938 } | |
| 1939 | |
| 1940 // A work method used by the foreground collector to do | |
| 1941 // a mark-sweep-compact. | |
| 1942 void CMSCollector::do_compaction_work(bool clear_all_soft_refs) { | |
| 1943 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 1944 TraceTime t("CMS:MSC ", PrintGCDetails && Verbose, true, gclog_or_tty); | |
| 1945 if (PrintGC && Verbose && !(GCCause::is_user_requested_gc(gch->gc_cause()))) { | |
| 1946 gclog_or_tty->print_cr("Compact ConcurrentMarkSweepGeneration after %d " | |
| 1947 "collections passed to foreground collector", _full_gcs_since_conc_gc); | |
| 1948 } | |
| 1949 | |
| 1950 // Sample collection interval time and reset for collection pause. | |
| 1951 if (UseAdaptiveSizePolicy) { | |
| 1952 size_policy()->msc_collection_begin(); | |
| 1953 } | |
| 1954 | |
| 1955 // Temporarily widen the span of the weak reference processing to | |
| 1956 // the entire heap. | |
| 1957 MemRegion new_span(GenCollectedHeap::heap()->reserved_region()); | |
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1958 ReferenceProcessorSpanMutator rp_mut_span(ref_processor(), new_span); |
| 0 | 1959 // Temporarily, clear the "is_alive_non_header" field of the |
| 1960 // reference processor. | |
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1961 ReferenceProcessorIsAliveMutator rp_mut_closure(ref_processor(), NULL); |
| 0 | 1962 // Temporarily make reference _processing_ single threaded (non-MT). |
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1963 ReferenceProcessorMTProcMutator rp_mut_mt_processing(ref_processor(), false); |
| 0 | 1964 // Temporarily make refs discovery atomic |
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1965 ReferenceProcessorAtomicMutator rp_mut_atomic(ref_processor(), true); |
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1966 // Temporarily make reference _discovery_ single threaded (non-MT) |
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1967 ReferenceProcessorMTDiscoveryMutator rp_mut_discovery(ref_processor(), false); |
| 0 | 1968 |
| 1969 ref_processor()->set_enqueuing_is_done(false); | |
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1970 ref_processor()->enable_discovery(false /*verify_disabled*/, false /*check_no_refs*/); |
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1971 ref_processor()->setup_policy(clear_all_soft_refs); |
| 0 | 1972 // If an asynchronous collection finishes, the _modUnionTable is |
| 1973 // all clear. If we are assuming the collection from an asynchronous | |
| 1974 // collection, clear the _modUnionTable. | |
| 1975 assert(_collectorState != Idling || _modUnionTable.isAllClear(), | |
| 1976 "_modUnionTable should be clear if the baton was not passed"); | |
| 1977 _modUnionTable.clear_all(); | |
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1978 assert(_collectorState != Idling || _ct->klass_rem_set()->mod_union_is_clear(), |
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1979 "mod union for klasses should be clear if the baton was passed"); |
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1980 _ct->klass_rem_set()->clear_mod_union(); |
| 0 | 1981 |
| 1982 // We must adjust the allocation statistics being maintained | |
| 1983 // in the free list space. We do so by reading and clearing | |
| 1984 // the sweep timer and updating the block flux rate estimates below. | |
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1985 assert(!_intra_sweep_timer.is_active(), "_intra_sweep_timer should be inactive"); |
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1986 if (_inter_sweep_timer.is_active()) { |
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1987 _inter_sweep_timer.stop(); |
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1988 // Note that we do not use this sample to update the _inter_sweep_estimate. |
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1989 _cmsGen->cmsSpace()->beginSweepFLCensus((float)(_inter_sweep_timer.seconds()), |
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1990 _inter_sweep_estimate.padded_average(), |
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1991 _intra_sweep_estimate.padded_average()); |
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1992 } |
| 0 | 1993 |
| 1994 GenMarkSweep::invoke_at_safepoint(_cmsGen->level(), | |
| 1995 ref_processor(), clear_all_soft_refs); | |
| 1996 #ifdef ASSERT | |
| 1997 CompactibleFreeListSpace* cms_space = _cmsGen->cmsSpace(); | |
| 1998 size_t free_size = cms_space->free(); | |
| 1999 assert(free_size == | |
| 2000 pointer_delta(cms_space->end(), cms_space->compaction_top()) | |
| 2001 * HeapWordSize, | |
| 2002 "All the free space should be compacted into one chunk at top"); | |
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2003 assert(cms_space->dictionary()->total_chunk_size( |
| 0 | 2004 debug_only(cms_space->freelistLock())) == 0 || |
| 2005 cms_space->totalSizeInIndexedFreeLists() == 0, | |
| 2006 "All the free space should be in a single chunk"); | |
| 2007 size_t num = cms_space->totalCount(); | |
| 2008 assert((free_size == 0 && num == 0) || | |
| 2009 (free_size > 0 && (num == 1 || num == 2)), | |
| 2010 "There should be at most 2 free chunks after compaction"); | |
| 2011 #endif // ASSERT | |
| 2012 _collectorState = Resetting; | |
| 2013 assert(_restart_addr == NULL, | |
| 2014 "Should have been NULL'd before baton was passed"); | |
| 2015 reset(false /* == !asynch */); | |
| 2016 _cmsGen->reset_after_compaction(); | |
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2017 _concurrent_cycles_since_last_unload = 0; |
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2018 |
| 0 | 2019 // Clear any data recorded in the PLAB chunk arrays. |
| 2020 if (_survivor_plab_array != NULL) { | |
| 2021 reset_survivor_plab_arrays(); | |
| 2022 } | |
| 2023 | |
| 2024 // Adjust the per-size allocation stats for the next epoch. | |
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2025 _cmsGen->cmsSpace()->endSweepFLCensus(sweep_count() /* fake */); |
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2026 // Restart the "inter sweep timer" for the next epoch. |
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2027 _inter_sweep_timer.reset(); |
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2028 _inter_sweep_timer.start(); |
| 0 | 2029 |
| 2030 // Sample collection pause time and reset for collection interval. | |
| 2031 if (UseAdaptiveSizePolicy) { | |
| 2032 size_policy()->msc_collection_end(gch->gc_cause()); | |
| 2033 } | |
| 2034 | |
| 2035 // For a mark-sweep-compact, compute_new_size() will be called | |
| 2036 // in the heap's do_collection() method. | |
| 2037 } | |
| 2038 | |
| 2039 // A work method used by the foreground collector to do | |
| 2040 // a mark-sweep, after taking over from a possibly on-going | |
| 2041 // concurrent mark-sweep collection. | |
| 2042 void CMSCollector::do_mark_sweep_work(bool clear_all_soft_refs, | |
| 2043 CollectorState first_state, bool should_start_over) { | |
| 2044 if (PrintGC && Verbose) { | |
| 2045 gclog_or_tty->print_cr("Pass concurrent collection to foreground " | |
| 2046 "collector with count %d", | |
| 2047 _full_gcs_since_conc_gc); | |
| 2048 } | |
| 2049 switch (_collectorState) { | |
| 2050 case Idling: | |
| 2051 if (first_state == Idling || should_start_over) { | |
| 2052 // The background GC was not active, or should | |
| 2053 // restarted from scratch; start the cycle. | |
| 2054 _collectorState = InitialMarking; | |
| 2055 } | |
| 2056 // If first_state was not Idling, then a background GC | |
| 2057 // was in progress and has now finished. No need to do it | |
| 2058 // again. Leave the state as Idling. | |
| 2059 break; | |
| 2060 case Precleaning: | |
| 2061 // In the foreground case don't do the precleaning since | |
| 2062 // it is not done concurrently and there is extra work | |
| 2063 // required. | |
| 2064 _collectorState = FinalMarking; | |
| 2065 } | |
| 2066 if (PrintGCDetails && | |
| 2067 (_collectorState > Idling || | |
| 2068 !GCCause::is_user_requested_gc(GenCollectedHeap::heap()->gc_cause()))) { | |
| 2069 gclog_or_tty->print(" (concurrent mode failure)"); | |
| 2070 } | |
| 2071 collect_in_foreground(clear_all_soft_refs); | |
| 2072 | |
| 2073 // For a mark-sweep, compute_new_size() will be called | |
| 2074 // in the heap's do_collection() method. | |
| 2075 } | |
| 2076 | |
| 2077 | |
| 2078 void CMSCollector::getFreelistLocks() const { | |
| 2079 // Get locks for all free lists in all generations that this | |
| 2080 // collector is responsible for | |
| 2081 _cmsGen->freelistLock()->lock_without_safepoint_check(); | |
| 2082 } | |
| 2083 | |
| 2084 void CMSCollector::releaseFreelistLocks() const { | |
| 2085 // Release locks for all free lists in all generations that this | |
| 2086 // collector is responsible for | |
| 2087 _cmsGen->freelistLock()->unlock(); | |
| 2088 } | |
| 2089 | |
| 2090 bool CMSCollector::haveFreelistLocks() const { | |
| 2091 // Check locks for all free lists in all generations that this | |
| 2092 // collector is responsible for | |
| 2093 assert_lock_strong(_cmsGen->freelistLock()); | |
| 2094 PRODUCT_ONLY(ShouldNotReachHere()); | |
| 2095 return true; | |
| 2096 } | |
| 2097 | |
| 2098 // A utility class that is used by the CMS collector to | |
| 2099 // temporarily "release" the foreground collector from its | |
| 2100 // usual obligation to wait for the background collector to | |
| 2101 // complete an ongoing phase before proceeding. | |
| 2102 class ReleaseForegroundGC: public StackObj { | |
| 2103 private: | |
| 2104 CMSCollector* _c; | |
| 2105 public: | |
| 2106 ReleaseForegroundGC(CMSCollector* c) : _c(c) { | |
| 2107 assert(_c->_foregroundGCShouldWait, "Else should not need to call"); | |
| 2108 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
| 2109 // allow a potentially blocked foreground collector to proceed | |
| 2110 _c->_foregroundGCShouldWait = false; | |
| 2111 if (_c->_foregroundGCIsActive) { | |
| 2112 CGC_lock->notify(); | |
| 2113 } | |
| 2114 assert(!ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 2115 "Possible deadlock"); | |
| 2116 } | |
| 2117 | |
| 2118 ~ReleaseForegroundGC() { | |
| 2119 assert(!_c->_foregroundGCShouldWait, "Usage protocol violation?"); | |
| 2120 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
| 2121 _c->_foregroundGCShouldWait = true; | |
| 2122 } | |
| 2123 }; | |
| 2124 | |
| 2125 // There are separate collect_in_background and collect_in_foreground because of | |
| 2126 // the different locking requirements of the background collector and the | |
| 2127 // foreground collector. There was originally an attempt to share | |
| 2128 // one "collect" method between the background collector and the foreground | |
| 2129 // collector but the if-then-else required made it cleaner to have | |
| 2130 // separate methods. | |
| 2131 void CMSCollector::collect_in_background(bool clear_all_soft_refs) { | |
| 2132 assert(Thread::current()->is_ConcurrentGC_thread(), | |
| 2133 "A CMS asynchronous collection is only allowed on a CMS thread."); | |
| 2134 | |
| 2135 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 2136 { | |
| 2137 bool safepoint_check = Mutex::_no_safepoint_check_flag; | |
| 2138 MutexLockerEx hl(Heap_lock, safepoint_check); | |
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2139 FreelistLocker fll(this); |
| 0 | 2140 MutexLockerEx x(CGC_lock, safepoint_check); |
| 2141 if (_foregroundGCIsActive || !UseAsyncConcMarkSweepGC) { | |
| 2142 // The foreground collector is active or we're | |
| 2143 // not using asynchronous collections. Skip this | |
| 2144 // background collection. | |
| 2145 assert(!_foregroundGCShouldWait, "Should be clear"); | |
| 2146 return; | |
| 2147 } else { | |
| 2148 assert(_collectorState == Idling, "Should be idling before start."); | |
| 2149 _collectorState = InitialMarking; | |
| 2150 // Reset the expansion cause, now that we are about to begin | |
| 2151 // a new cycle. | |
| 2152 clear_expansion_cause(); | |
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2153 |
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2154 // Clear the MetaspaceGC flag since a concurrent collection |
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2155 // is starting but also clear it after the collection. |
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2156 MetaspaceGC::set_should_concurrent_collect(false); |
| 0 | 2157 } |
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2158 // Decide if we want to enable class unloading as part of the |
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2159 // ensuing concurrent GC cycle. |
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2160 update_should_unload_classes(); |
| 0 | 2161 _full_gc_requested = false; // acks all outstanding full gc requests |
| 2162 // Signal that we are about to start a collection | |
| 2163 gch->increment_total_full_collections(); // ... starting a collection cycle | |
| 2164 _collection_count_start = gch->total_full_collections(); | |
| 2165 } | |
| 2166 | |
| 2167 // Used for PrintGC | |
| 2168 size_t prev_used; | |
| 2169 if (PrintGC && Verbose) { | |
| 2170 prev_used = _cmsGen->used(); // XXXPERM | |
| 2171 } | |
| 2172 | |
| 2173 // The change of the collection state is normally done at this level; | |
| 2174 // the exceptions are phases that are executed while the world is | |
| 2175 // stopped. For those phases the change of state is done while the | |
| 2176 // world is stopped. For baton passing purposes this allows the | |
| 2177 // background collector to finish the phase and change state atomically. | |
| 2178 // The foreground collector cannot wait on a phase that is done | |
| 2179 // while the world is stopped because the foreground collector already | |
| 2180 // has the world stopped and would deadlock. | |
| 2181 while (_collectorState != Idling) { | |
| 2182 if (TraceCMSState) { | |
| 2183 gclog_or_tty->print_cr("Thread " INTPTR_FORMAT " in CMS state %d", | |
| 2184 Thread::current(), _collectorState); | |
| 2185 } | |
| 2186 // The foreground collector | |
| 2187 // holds the Heap_lock throughout its collection. | |
| 2188 // holds the CMS token (but not the lock) | |
| 2189 // except while it is waiting for the background collector to yield. | |
| 2190 // | |
| 2191 // The foreground collector should be blocked (not for long) | |
| 2192 // if the background collector is about to start a phase | |
| 2193 // executed with world stopped. If the background | |
| 2194 // collector has already started such a phase, the | |
| 2195 // foreground collector is blocked waiting for the | |
| 2196 // Heap_lock. The stop-world phases (InitialMarking and FinalMarking) | |
| 2197 // are executed in the VM thread. | |
| 2198 // | |
| 2199 // The locking order is | |
| 2200 // PendingListLock (PLL) -- if applicable (FinalMarking) | |
| 2201 // Heap_lock (both this & PLL locked in VM_CMS_Operation::prologue()) | |
| 2202 // CMS token (claimed in | |
| 2203 // stop_world_and_do() --> | |
| 2204 // safepoint_synchronize() --> | |
| 2205 // CMSThread::synchronize()) | |
| 2206 | |
| 2207 { | |
| 2208 // Check if the FG collector wants us to yield. | |
| 2209 CMSTokenSync x(true); // is cms thread | |
| 2210 if (waitForForegroundGC()) { | |
| 2211 // We yielded to a foreground GC, nothing more to be | |
| 2212 // done this round. | |
| 2213 assert(_foregroundGCShouldWait == false, "We set it to false in " | |
| 2214 "waitForForegroundGC()"); | |
| 2215 if (TraceCMSState) { | |
| 2216 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT | |
| 2217 " exiting collection CMS state %d", | |
| 2218 Thread::current(), _collectorState); | |
| 2219 } | |
| 2220 return; | |
| 2221 } else { | |
| 2222 // The background collector can run but check to see if the | |
| 2223 // foreground collector has done a collection while the | |
| 2224 // background collector was waiting to get the CGC_lock | |
| 2225 // above. If yes, break so that _foregroundGCShouldWait | |
| 2226 // is cleared before returning. | |
| 2227 if (_collectorState == Idling) { | |
| 2228 break; | |
| 2229 } | |
| 2230 } | |
| 2231 } | |
| 2232 | |
| 2233 assert(_foregroundGCShouldWait, "Foreground collector, if active, " | |
| 2234 "should be waiting"); | |
| 2235 | |
| 2236 switch (_collectorState) { | |
| 2237 case InitialMarking: | |
| 2238 { | |
| 2239 ReleaseForegroundGC x(this); | |
| 2240 stats().record_cms_begin(); | |
| 2241 | |
| 2242 VM_CMS_Initial_Mark initial_mark_op(this); | |
| 2243 VMThread::execute(&initial_mark_op); | |
| 2244 } | |
| 2245 // The collector state may be any legal state at this point | |
| 2246 // since the background collector may have yielded to the | |
| 2247 // foreground collector. | |
| 2248 break; | |
| 2249 case Marking: | |
| 2250 // initial marking in checkpointRootsInitialWork has been completed | |
| 2251 if (markFromRoots(true)) { // we were successful | |
| 2252 assert(_collectorState == Precleaning, "Collector state should " | |
| 2253 "have changed"); | |
| 2254 } else { | |
| 2255 assert(_foregroundGCIsActive, "Internal state inconsistency"); | |
| 2256 } | |
| 2257 break; | |
| 2258 case Precleaning: | |
| 2259 if (UseAdaptiveSizePolicy) { | |
| 2260 size_policy()->concurrent_precleaning_begin(); | |
| 2261 } | |
| 2262 // marking from roots in markFromRoots has been completed | |
| 2263 preclean(); | |
| 2264 if (UseAdaptiveSizePolicy) { | |
| 2265 size_policy()->concurrent_precleaning_end(); | |
| 2266 } | |
| 2267 assert(_collectorState == AbortablePreclean || | |
| 2268 _collectorState == FinalMarking, | |
| 2269 "Collector state should have changed"); | |
| 2270 break; | |
| 2271 case AbortablePreclean: | |
| 2272 if (UseAdaptiveSizePolicy) { | |
| 2273 size_policy()->concurrent_phases_resume(); | |
| 2274 } | |
| 2275 abortable_preclean(); | |
| 2276 if (UseAdaptiveSizePolicy) { | |
| 2277 size_policy()->concurrent_precleaning_end(); | |
| 2278 } | |
| 2279 assert(_collectorState == FinalMarking, "Collector state should " | |
| 2280 "have changed"); | |
| 2281 break; | |
| 2282 case FinalMarking: | |
| 2283 { | |
| 2284 ReleaseForegroundGC x(this); | |
| 2285 | |
| 2286 VM_CMS_Final_Remark final_remark_op(this); | |
| 2287 VMThread::execute(&final_remark_op); | |
| 935 | 2288 } |
| 0 | 2289 assert(_foregroundGCShouldWait, "block post-condition"); |
| 2290 break; | |
| 2291 case Sweeping: | |
| 2292 if (UseAdaptiveSizePolicy) { | |
| 2293 size_policy()->concurrent_sweeping_begin(); | |
| 2294 } | |
| 2295 // final marking in checkpointRootsFinal has been completed | |
| 2296 sweep(true); | |
| 2297 assert(_collectorState == Resizing, "Collector state change " | |
| 2298 "to Resizing must be done under the free_list_lock"); | |
| 2299 _full_gcs_since_conc_gc = 0; | |
| 2300 | |
| 2301 // Stop the timers for adaptive size policy for the concurrent phases | |
| 2302 if (UseAdaptiveSizePolicy) { | |
| 2303 size_policy()->concurrent_sweeping_end(); | |
| 2304 size_policy()->concurrent_phases_end(gch->gc_cause(), | |
| 2305 gch->prev_gen(_cmsGen)->capacity(), | |
| 2306 _cmsGen->free()); | |
| 2307 } | |
| 2308 | |
| 2309 case Resizing: { | |
| 2310 // Sweeping has been completed... | |
| 2311 // At this point the background collection has completed. | |
| 2312 // Don't move the call to compute_new_size() down | |
| 2313 // into code that might be executed if the background | |
| 2314 // collection was preempted. | |
| 2315 { | |
| 2316 ReleaseForegroundGC x(this); // unblock FG collection | |
| 2317 MutexLockerEx y(Heap_lock, Mutex::_no_safepoint_check_flag); | |
| 2318 CMSTokenSync z(true); // not strictly needed. | |
| 2319 if (_collectorState == Resizing) { | |
| 2320 compute_new_size(); | |
| 2321 _collectorState = Resetting; | |
| 2322 } else { | |
| 2323 assert(_collectorState == Idling, "The state should only change" | |
| 2324 " because the foreground collector has finished the collection"); | |
| 2325 } | |
| 2326 } | |
| 2327 break; | |
| 2328 } | |
| 2329 case Resetting: | |
| 2330 // CMS heap resizing has been completed | |
| 2331 reset(true); | |
| 2332 assert(_collectorState == Idling, "Collector state should " | |
| 2333 "have changed"); | |
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2334 |
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2335 MetaspaceGC::set_should_concurrent_collect(false); |
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2336 |
| 0 | 2337 stats().record_cms_end(); |
| 2338 // Don't move the concurrent_phases_end() and compute_new_size() | |
| 2339 // calls to here because a preempted background collection | |
| 2340 // has it's state set to "Resetting". | |
| 2341 break; | |
| 2342 case Idling: | |
| 2343 default: | |
| 2344 ShouldNotReachHere(); | |
| 2345 break; | |
| 2346 } | |
| 2347 if (TraceCMSState) { | |
| 2348 gclog_or_tty->print_cr(" Thread " INTPTR_FORMAT " done - next CMS state %d", | |
| 2349 Thread::current(), _collectorState); | |
| 2350 } | |
| 2351 assert(_foregroundGCShouldWait, "block post-condition"); | |
| 2352 } | |
| 2353 | |
| 2354 // Should this be in gc_epilogue? | |
| 2355 collector_policy()->counters()->update_counters(); | |
| 2356 | |
| 2357 { | |
| 2358 // Clear _foregroundGCShouldWait and, in the event that the | |
| 2359 // foreground collector is waiting, notify it, before | |
| 2360 // returning. | |
| 2361 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
| 2362 _foregroundGCShouldWait = false; | |
| 2363 if (_foregroundGCIsActive) { | |
| 2364 CGC_lock->notify(); | |
| 2365 } | |
| 2366 assert(!ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 2367 "Possible deadlock"); | |
| 2368 } | |
| 2369 if (TraceCMSState) { | |
| 2370 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT | |
| 2371 " exiting collection CMS state %d", | |
| 2372 Thread::current(), _collectorState); | |
| 2373 } | |
| 2374 if (PrintGC && Verbose) { | |
| 2375 _cmsGen->print_heap_change(prev_used); | |
| 2376 } | |
| 2377 } | |
| 2378 | |
| 2379 void CMSCollector::collect_in_foreground(bool clear_all_soft_refs) { | |
| 2380 assert(_foregroundGCIsActive && !_foregroundGCShouldWait, | |
| 2381 "Foreground collector should be waiting, not executing"); | |
| 2382 assert(Thread::current()->is_VM_thread(), "A foreground collection" | |
| 2383 "may only be done by the VM Thread with the world stopped"); | |
| 2384 assert(ConcurrentMarkSweepThread::vm_thread_has_cms_token(), | |
| 2385 "VM thread should have CMS token"); | |
| 2386 | |
| 2387 NOT_PRODUCT(TraceTime t("CMS:MS (foreground) ", PrintGCDetails && Verbose, | |
| 2388 true, gclog_or_tty);) | |
| 2389 if (UseAdaptiveSizePolicy) { | |
| 2390 size_policy()->ms_collection_begin(); | |
| 2391 } | |
| 2392 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact); | |
| 2393 | |
| 2394 HandleMark hm; // Discard invalid handles created during verification | |
| 2395 | |
| 2396 if (VerifyBeforeGC && | |
| 2397 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
|
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2398 Universe::verify(); |
| 0 | 2399 } |
| 2400 | |
|
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2401 // Snapshot the soft reference policy to be used in this collection cycle. |
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2402 ref_processor()->setup_policy(clear_all_soft_refs); |
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2403 |
| 0 | 2404 bool init_mark_was_synchronous = false; // until proven otherwise |
| 2405 while (_collectorState != Idling) { | |
| 2406 if (TraceCMSState) { | |
| 2407 gclog_or_tty->print_cr("Thread " INTPTR_FORMAT " in CMS state %d", | |
| 2408 Thread::current(), _collectorState); | |
| 2409 } | |
| 2410 switch (_collectorState) { | |
| 2411 case InitialMarking: | |
| 2412 init_mark_was_synchronous = true; // fact to be exploited in re-mark | |
| 2413 checkpointRootsInitial(false); | |
| 2414 assert(_collectorState == Marking, "Collector state should have changed" | |
| 2415 " within checkpointRootsInitial()"); | |
| 2416 break; | |
| 2417 case Marking: | |
| 2418 // initial marking in checkpointRootsInitialWork has been completed | |
| 2419 if (VerifyDuringGC && | |
| 2420 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
| 2421 gclog_or_tty->print("Verify before initial mark: "); | |
|
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|
2422 Universe::verify(); |
| 0 | 2423 } |
| 2424 { | |
| 2425 bool res = markFromRoots(false); | |
| 2426 assert(res && _collectorState == FinalMarking, "Collector state should " | |
| 2427 "have changed"); | |
| 2428 break; | |
| 2429 } | |
| 2430 case FinalMarking: | |
| 2431 if (VerifyDuringGC && | |
| 2432 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
| 2433 gclog_or_tty->print("Verify before re-mark: "); | |
|
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|
2434 Universe::verify(); |
| 0 | 2435 } |
| 2436 checkpointRootsFinal(false, clear_all_soft_refs, | |
| 2437 init_mark_was_synchronous); | |
| 2438 assert(_collectorState == Sweeping, "Collector state should not " | |
| 2439 "have changed within checkpointRootsFinal()"); | |
| 2440 break; | |
| 2441 case Sweeping: | |
| 2442 // final marking in checkpointRootsFinal has been completed | |
| 2443 if (VerifyDuringGC && | |
| 2444 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
| 2445 gclog_or_tty->print("Verify before sweep: "); | |
|
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|
2446 Universe::verify(); |
| 0 | 2447 } |
| 2448 sweep(false); | |
| 2449 assert(_collectorState == Resizing, "Incorrect state"); | |
| 2450 break; | |
| 2451 case Resizing: { | |
| 2452 // Sweeping has been completed; the actual resize in this case | |
| 2453 // is done separately; nothing to be done in this state. | |
| 2454 _collectorState = Resetting; | |
| 2455 break; | |
| 2456 } | |
| 2457 case Resetting: | |
| 2458 // The heap has been resized. | |
| 2459 if (VerifyDuringGC && | |
| 2460 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
| 2461 gclog_or_tty->print("Verify before reset: "); | |
|
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|
2462 Universe::verify(); |
| 0 | 2463 } |
| 2464 reset(false); | |
| 2465 assert(_collectorState == Idling, "Collector state should " | |
| 2466 "have changed"); | |
| 2467 break; | |
| 2468 case Precleaning: | |
| 2469 case AbortablePreclean: | |
| 2470 // Elide the preclean phase | |
| 2471 _collectorState = FinalMarking; | |
| 2472 break; | |
| 2473 default: | |
| 2474 ShouldNotReachHere(); | |
| 2475 } | |
| 2476 if (TraceCMSState) { | |
| 2477 gclog_or_tty->print_cr(" Thread " INTPTR_FORMAT " done - next CMS state %d", | |
| 2478 Thread::current(), _collectorState); | |
| 2479 } | |
| 2480 } | |
| 2481 | |
| 2482 if (UseAdaptiveSizePolicy) { | |
| 2483 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 2484 size_policy()->ms_collection_end(gch->gc_cause()); | |
| 2485 } | |
| 2486 | |
| 2487 if (VerifyAfterGC && | |
| 2488 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
|
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|
2489 Universe::verify(); |
| 0 | 2490 } |
| 2491 if (TraceCMSState) { | |
| 2492 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT | |
| 2493 " exiting collection CMS state %d", | |
| 2494 Thread::current(), _collectorState); | |
| 2495 } | |
| 2496 } | |
| 2497 | |
| 2498 bool CMSCollector::waitForForegroundGC() { | |
| 2499 bool res = false; | |
| 2500 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 2501 "CMS thread should have CMS token"); | |
| 2502 // Block the foreground collector until the | |
| 2503 // background collectors decides whether to | |
| 2504 // yield. | |
| 2505 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
| 2506 _foregroundGCShouldWait = true; | |
| 2507 if (_foregroundGCIsActive) { | |
| 2508 // The background collector yields to the | |
| 2509 // foreground collector and returns a value | |
| 2510 // indicating that it has yielded. The foreground | |
| 2511 // collector can proceed. | |
| 2512 res = true; | |
| 2513 _foregroundGCShouldWait = false; | |
| 2514 ConcurrentMarkSweepThread::clear_CMS_flag( | |
| 2515 ConcurrentMarkSweepThread::CMS_cms_has_token); | |
| 2516 ConcurrentMarkSweepThread::set_CMS_flag( | |
| 2517 ConcurrentMarkSweepThread::CMS_cms_wants_token); | |
| 2518 // Get a possibly blocked foreground thread going | |
| 2519 CGC_lock->notify(); | |
| 2520 if (TraceCMSState) { | |
| 2521 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT " waiting at CMS state %d", | |
| 2522 Thread::current(), _collectorState); | |
| 2523 } | |
| 2524 while (_foregroundGCIsActive) { | |
| 2525 CGC_lock->wait(Mutex::_no_safepoint_check_flag); | |
| 2526 } | |
| 2527 ConcurrentMarkSweepThread::set_CMS_flag( | |
| 2528 ConcurrentMarkSweepThread::CMS_cms_has_token); | |
| 2529 ConcurrentMarkSweepThread::clear_CMS_flag( | |
| 2530 ConcurrentMarkSweepThread::CMS_cms_wants_token); | |
| 2531 } | |
| 2532 if (TraceCMSState) { | |
| 2533 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT " continuing at CMS state %d", | |
| 2534 Thread::current(), _collectorState); | |
| 2535 } | |
| 2536 return res; | |
| 2537 } | |
| 2538 | |
| 2539 // Because of the need to lock the free lists and other structures in | |
| 2540 // the collector, common to all the generations that the collector is | |
| 2541 // collecting, we need the gc_prologues of individual CMS generations | |
| 2542 // delegate to their collector. It may have been simpler had the | |
| 2543 // current infrastructure allowed one to call a prologue on a | |
| 2544 // collector. In the absence of that we have the generation's | |
| 2545 // prologue delegate to the collector, which delegates back | |
| 2546 // some "local" work to a worker method in the individual generations | |
| 2547 // that it's responsible for collecting, while itself doing any | |
| 2548 // work common to all generations it's responsible for. A similar | |
| 2549 // comment applies to the gc_epilogue()'s. | |
| 2550 // The role of the varaible _between_prologue_and_epilogue is to | |
| 2551 // enforce the invocation protocol. | |
| 2552 void CMSCollector::gc_prologue(bool full) { | |
|
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2553 // Call gc_prologue_work() for the CMSGen |
| 0 | 2554 // we are responsible for. |
| 2555 | |
| 2556 // The following locking discipline assumes that we are only called | |
| 2557 // when the world is stopped. | |
| 2558 assert(SafepointSynchronize::is_at_safepoint(), "world is stopped assumption"); | |
| 2559 | |
| 2560 // The CMSCollector prologue must call the gc_prologues for the | |
|
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2561 // "generations" that it's responsible |
| 0 | 2562 // for. |
| 2563 | |
| 2564 assert( Thread::current()->is_VM_thread() | |
| 2565 || ( CMSScavengeBeforeRemark | |
| 2566 && Thread::current()->is_ConcurrentGC_thread()), | |
| 2567 "Incorrect thread type for prologue execution"); | |
| 2568 | |
| 2569 if (_between_prologue_and_epilogue) { | |
| 2570 // We have already been invoked; this is a gc_prologue delegation | |
| 2571 // from yet another CMS generation that we are responsible for, just | |
| 2572 // ignore it since all relevant work has already been done. | |
| 2573 return; | |
| 2574 } | |
| 2575 | |
| 2576 // set a bit saying prologue has been called; cleared in epilogue | |
| 2577 _between_prologue_and_epilogue = true; | |
| 2578 // Claim locks for common data structures, then call gc_prologue_work() | |
|
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2579 // for each CMSGen. |
| 0 | 2580 |
| 2581 getFreelistLocks(); // gets free list locks on constituent spaces | |
| 2582 bitMapLock()->lock_without_safepoint_check(); | |
| 2583 | |
| 2584 // Should call gc_prologue_work() for all cms gens we are responsible for | |
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2585 bool duringMarking = _collectorState >= Marking |
| 0 | 2586 && _collectorState < Sweeping; |
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2587 |
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2588 // The young collections clear the modified oops state, which tells if |
|
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2589 // there are any modified oops in the class. The remark phase also needs |
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2590 // that information. Tell the young collection to save the union of all |
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2591 // modified klasses. |
|
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|
2592 if (duringMarking) { |
|
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2593 _ct->klass_rem_set()->set_accumulate_modified_oops(true); |
|
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|
2594 } |
|
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|
2595 |
|
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|
2596 bool registerClosure = duringMarking; |
|
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2597 |
|
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2598 ModUnionClosure* muc = CollectedHeap::use_parallel_gc_threads() ? |
|
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|
2599 &_modUnionClosurePar |
| 0 | 2600 : &_modUnionClosure; |
| 2601 _cmsGen->gc_prologue_work(full, registerClosure, muc); | |
| 2602 | |
| 2603 if (!full) { | |
| 2604 stats().record_gc0_begin(); | |
| 2605 } | |
| 2606 } | |
| 2607 | |
| 2608 void ConcurrentMarkSweepGeneration::gc_prologue(bool full) { | |
| 2609 // Delegate to CMScollector which knows how to coordinate between | |
| 2610 // this and any other CMS generations that it is responsible for | |
| 2611 // collecting. | |
| 2612 collector()->gc_prologue(full); | |
| 2613 } | |
| 2614 | |
| 2615 // This is a "private" interface for use by this generation's CMSCollector. | |
| 2616 // Not to be called directly by any other entity (for instance, | |
| 2617 // GenCollectedHeap, which calls the "public" gc_prologue method above). | |
| 2618 void ConcurrentMarkSweepGeneration::gc_prologue_work(bool full, | |
| 2619 bool registerClosure, ModUnionClosure* modUnionClosure) { | |
| 2620 assert(!incremental_collection_failed(), "Shouldn't be set yet"); | |
| 2621 assert(cmsSpace()->preconsumptionDirtyCardClosure() == NULL, | |
| 2622 "Should be NULL"); | |
| 2623 if (registerClosure) { | |
| 2624 cmsSpace()->setPreconsumptionDirtyCardClosure(modUnionClosure); | |
| 2625 } | |
| 2626 cmsSpace()->gc_prologue(); | |
| 2627 // Clear stat counters | |
| 2628 NOT_PRODUCT( | |
| 2629 assert(_numObjectsPromoted == 0, "check"); | |
| 2630 assert(_numWordsPromoted == 0, "check"); | |
| 2631 if (Verbose && PrintGC) { | |
| 2632 gclog_or_tty->print("Allocated "SIZE_FORMAT" objects, " | |
| 2633 SIZE_FORMAT" bytes concurrently", | |
| 2634 _numObjectsAllocated, _numWordsAllocated*sizeof(HeapWord)); | |
| 2635 } | |
| 2636 _numObjectsAllocated = 0; | |
| 2637 _numWordsAllocated = 0; | |
| 2638 ) | |
| 2639 } | |
| 2640 | |
| 2641 void CMSCollector::gc_epilogue(bool full) { | |
| 2642 // The following locking discipline assumes that we are only called | |
| 2643 // when the world is stopped. | |
| 2644 assert(SafepointSynchronize::is_at_safepoint(), | |
| 2645 "world is stopped assumption"); | |
| 2646 | |
| 2647 // Currently the CMS epilogue (see CompactibleFreeListSpace) merely checks | |
| 2648 // if linear allocation blocks need to be appropriately marked to allow the | |
| 2649 // the blocks to be parsable. We also check here whether we need to nudge the | |
| 2650 // CMS collector thread to start a new cycle (if it's not already active). | |
| 2651 assert( Thread::current()->is_VM_thread() | |
| 2652 || ( CMSScavengeBeforeRemark | |
| 2653 && Thread::current()->is_ConcurrentGC_thread()), | |
| 2654 "Incorrect thread type for epilogue execution"); | |
| 2655 | |
| 2656 if (!_between_prologue_and_epilogue) { | |
| 2657 // We have already been invoked; this is a gc_epilogue delegation | |
| 2658 // from yet another CMS generation that we are responsible for, just | |
| 2659 // ignore it since all relevant work has already been done. | |
| 2660 return; | |
| 2661 } | |
| 2662 assert(haveFreelistLocks(), "must have freelist locks"); | |
| 2663 assert_lock_strong(bitMapLock()); | |
| 2664 | |
|
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2665 _ct->klass_rem_set()->set_accumulate_modified_oops(false); |
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|
2666 |
| 0 | 2667 _cmsGen->gc_epilogue_work(full); |
| 2668 | |
| 2669 if (_collectorState == AbortablePreclean || _collectorState == Precleaning) { | |
| 2670 // in case sampling was not already enabled, enable it | |
| 2671 _start_sampling = true; | |
| 2672 } | |
| 2673 // reset _eden_chunk_array so sampling starts afresh | |
| 2674 _eden_chunk_index = 0; | |
| 2675 | |
| 2676 size_t cms_used = _cmsGen->cmsSpace()->used(); | |
| 2677 | |
| 2678 // update performance counters - this uses a special version of | |
| 2679 // update_counters() that allows the utilization to be passed as a | |
| 2680 // parameter, avoiding multiple calls to used(). | |
| 2681 // | |
| 2682 _cmsGen->update_counters(cms_used); | |
| 2683 | |
| 2684 if (CMSIncrementalMode) { | |
| 2685 icms_update_allocation_limits(); | |
| 2686 } | |
| 2687 | |
| 2688 bitMapLock()->unlock(); | |
| 2689 releaseFreelistLocks(); | |
| 2690 | |
|
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2691 if (!CleanChunkPoolAsync) { |
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2692 Chunk::clean_chunk_pool(); |
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|
2693 } |
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2694 |
| 0 | 2695 _between_prologue_and_epilogue = false; // ready for next cycle |
| 2696 } | |
| 2697 | |
| 2698 void ConcurrentMarkSweepGeneration::gc_epilogue(bool full) { | |
| 2699 collector()->gc_epilogue(full); | |
| 2700 | |
| 2701 // Also reset promotion tracking in par gc thread states. | |
|
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2702 if (CollectedHeap::use_parallel_gc_threads()) { |
| 0 | 2703 for (uint i = 0; i < ParallelGCThreads; i++) { |
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2704 _par_gc_thread_states[i]->promo.stopTrackingPromotions(i); |
| 0 | 2705 } |
| 2706 } | |
| 2707 } | |
| 2708 | |
| 2709 void ConcurrentMarkSweepGeneration::gc_epilogue_work(bool full) { | |
| 2710 assert(!incremental_collection_failed(), "Should have been cleared"); | |
| 2711 cmsSpace()->setPreconsumptionDirtyCardClosure(NULL); | |
| 2712 cmsSpace()->gc_epilogue(); | |
| 2713 // Print stat counters | |
| 2714 NOT_PRODUCT( | |
| 2715 assert(_numObjectsAllocated == 0, "check"); | |
| 2716 assert(_numWordsAllocated == 0, "check"); | |
| 2717 if (Verbose && PrintGC) { | |
| 2718 gclog_or_tty->print("Promoted "SIZE_FORMAT" objects, " | |
| 2719 SIZE_FORMAT" bytes", | |
| 2720 _numObjectsPromoted, _numWordsPromoted*sizeof(HeapWord)); | |
| 2721 } | |
| 2722 _numObjectsPromoted = 0; | |
| 2723 _numWordsPromoted = 0; | |
| 2724 ) | |
| 2725 | |
| 2726 if (PrintGC && Verbose) { | |
| 2727 // Call down the chain in contiguous_available needs the freelistLock | |
| 2728 // so print this out before releasing the freeListLock. | |
| 2729 gclog_or_tty->print(" Contiguous available "SIZE_FORMAT" bytes ", | |
| 2730 contiguous_available()); | |
| 2731 } | |
| 2732 } | |
| 2733 | |
| 2734 #ifndef PRODUCT | |
| 2735 bool CMSCollector::have_cms_token() { | |
| 2736 Thread* thr = Thread::current(); | |
| 2737 if (thr->is_VM_thread()) { | |
| 2738 return ConcurrentMarkSweepThread::vm_thread_has_cms_token(); | |
| 2739 } else if (thr->is_ConcurrentGC_thread()) { | |
| 2740 return ConcurrentMarkSweepThread::cms_thread_has_cms_token(); | |
| 2741 } else if (thr->is_GC_task_thread()) { | |
| 2742 return ConcurrentMarkSweepThread::vm_thread_has_cms_token() && | |
| 2743 ParGCRareEvent_lock->owned_by_self(); | |
| 2744 } | |
| 2745 return false; | |
| 2746 } | |
| 2747 #endif | |
| 2748 | |
| 2749 // Check reachability of the given heap address in CMS generation, | |
| 2750 // treating all other generations as roots. | |
| 2751 bool CMSCollector::is_cms_reachable(HeapWord* addr) { | |
| 2752 // We could "guarantee" below, rather than assert, but i'll | |
| 2753 // leave these as "asserts" so that an adventurous debugger | |
| 2754 // could try this in the product build provided some subset of | |
| 2755 // the conditions were met, provided they were intersted in the | |
| 2756 // results and knew that the computation below wouldn't interfere | |
| 2757 // with other concurrent computations mutating the structures | |
| 2758 // being read or written. | |
| 2759 assert(SafepointSynchronize::is_at_safepoint(), | |
| 2760 "Else mutations in object graph will make answer suspect"); | |
| 2761 assert(have_cms_token(), "Should hold cms token"); | |
| 2762 assert(haveFreelistLocks(), "must hold free list locks"); | |
| 2763 assert_lock_strong(bitMapLock()); | |
| 2764 | |
| 2765 // Clear the marking bit map array before starting, but, just | |
| 2766 // for kicks, first report if the given address is already marked | |
| 2767 gclog_or_tty->print_cr("Start: Address 0x%x is%s marked", addr, | |
| 2768 _markBitMap.isMarked(addr) ? "" : " not"); | |
| 2769 | |
| 2770 if (verify_after_remark()) { | |
| 2771 MutexLockerEx x(verification_mark_bm()->lock(), Mutex::_no_safepoint_check_flag); | |
| 2772 bool result = verification_mark_bm()->isMarked(addr); | |
| 2773 gclog_or_tty->print_cr("TransitiveMark: Address 0x%x %s marked", addr, | |
| 2774 result ? "IS" : "is NOT"); | |
| 2775 return result; | |
| 2776 } else { | |
| 2777 gclog_or_tty->print_cr("Could not compute result"); | |
| 2778 return false; | |
| 2779 } | |
| 2780 } | |
| 2781 | |
| 2782 //////////////////////////////////////////////////////// | |
| 2783 // CMS Verification Support | |
| 2784 //////////////////////////////////////////////////////// | |
| 2785 // Following the remark phase, the following invariant | |
| 2786 // should hold -- each object in the CMS heap which is | |
| 2787 // marked in markBitMap() should be marked in the verification_mark_bm(). | |
| 2788 | |
| 2789 class VerifyMarkedClosure: public BitMapClosure { | |
| 2790 CMSBitMap* _marks; | |
| 2791 bool _failed; | |
| 2792 | |
| 2793 public: | |
| 2794 VerifyMarkedClosure(CMSBitMap* bm): _marks(bm), _failed(false) {} | |
| 2795 | |
|
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2796 bool do_bit(size_t offset) { |
| 0 | 2797 HeapWord* addr = _marks->offsetToHeapWord(offset); |
| 2798 if (!_marks->isMarked(addr)) { | |
|
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2799 oop(addr)->print_on(gclog_or_tty); |
| 0 | 2800 gclog_or_tty->print_cr(" ("INTPTR_FORMAT" should have been marked)", addr); |
| 2801 _failed = true; | |
| 2802 } | |
|
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2803 return true; |
| 0 | 2804 } |
| 2805 | |
| 2806 bool failed() { return _failed; } | |
| 2807 }; | |
| 2808 | |
| 2809 bool CMSCollector::verify_after_remark() { | |
| 2810 gclog_or_tty->print(" [Verifying CMS Marking... "); | |
| 2811 MutexLockerEx ml(verification_mark_bm()->lock(), Mutex::_no_safepoint_check_flag); | |
| 2812 static bool init = false; | |
| 2813 | |
| 2814 assert(SafepointSynchronize::is_at_safepoint(), | |
| 2815 "Else mutations in object graph will make answer suspect"); | |
| 2816 assert(have_cms_token(), | |
| 2817 "Else there may be mutual interference in use of " | |
| 2818 " verification data structures"); | |
| 2819 assert(_collectorState > Marking && _collectorState <= Sweeping, | |
| 2820 "Else marking info checked here may be obsolete"); | |
| 2821 assert(haveFreelistLocks(), "must hold free list locks"); | |
| 2822 assert_lock_strong(bitMapLock()); | |
| 2823 | |
| 2824 | |
| 2825 // Allocate marking bit map if not already allocated | |
| 2826 if (!init) { // first time | |
| 2827 if (!verification_mark_bm()->allocate(_span)) { | |
| 2828 return false; | |
| 2829 } | |
| 2830 init = true; | |
| 2831 } | |
| 2832 | |
| 2833 assert(verification_mark_stack()->isEmpty(), "Should be empty"); | |
| 2834 | |
| 2835 // Turn off refs discovery -- so we will be tracing through refs. | |
| 2836 // This is as intended, because by this time | |
| 2837 // GC must already have cleared any refs that need to be cleared, | |
| 2838 // and traced those that need to be marked; moreover, | |
| 2839 // the marking done here is not going to intefere in any | |
| 2840 // way with the marking information used by GC. | |
| 2841 NoRefDiscovery no_discovery(ref_processor()); | |
| 2842 | |
| 2843 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact;) | |
| 2844 | |
| 2845 // Clear any marks from a previous round | |
| 2846 verification_mark_bm()->clear_all(); | |
| 2847 assert(verification_mark_stack()->isEmpty(), "markStack should be empty"); | |
|
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2848 verify_work_stacks_empty(); |
| 0 | 2849 |
| 2850 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 2851 gch->ensure_parsability(false); // fill TLABs, but no need to retire them | |
| 2852 // Update the saved marks which may affect the root scans. | |
| 2853 gch->save_marks(); | |
| 2854 | |
| 2855 if (CMSRemarkVerifyVariant == 1) { | |
| 2856 // In this first variant of verification, we complete | |
| 2857 // all marking, then check if the new marks-verctor is | |
| 2858 // a subset of the CMS marks-vector. | |
| 2859 verify_after_remark_work_1(); | |
| 2860 } else if (CMSRemarkVerifyVariant == 2) { | |
| 2861 // In this second variant of verification, we flag an error | |
| 2862 // (i.e. an object reachable in the new marks-vector not reachable | |
| 2863 // in the CMS marks-vector) immediately, also indicating the | |
| 2864 // identify of an object (A) that references the unmarked object (B) -- | |
| 2865 // presumably, a mutation to A failed to be picked up by preclean/remark? | |
| 2866 verify_after_remark_work_2(); | |
| 2867 } else { | |
| 2868 warning("Unrecognized value %d for CMSRemarkVerifyVariant", | |
| 2869 CMSRemarkVerifyVariant); | |
| 2870 } | |
| 2871 gclog_or_tty->print(" done] "); | |
| 2872 return true; | |
| 2873 } | |
| 2874 | |
| 2875 void CMSCollector::verify_after_remark_work_1() { | |
| 2876 ResourceMark rm; | |
| 2877 HandleMark hm; | |
| 2878 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 2879 | |
|
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2880 // Get a clear set of claim bits for the strong roots processing to work with. |
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2881 ClassLoaderDataGraph::clear_claimed_marks(); |
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2882 |
| 0 | 2883 // Mark from roots one level into CMS |
|
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2884 MarkRefsIntoClosure notOlder(_span, verification_mark_bm()); |
| 0 | 2885 gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel. |
| 2886 | |
| 2887 gch->gen_process_strong_roots(_cmsGen->level(), | |
| 2888 true, // younger gens are roots | |
|
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2889 true, // activate StrongRootsScope |
|
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2890 false, // not scavenging |
| 0 | 2891 SharedHeap::ScanningOption(roots_scanning_options()), |
|
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2892 ¬Older, |
|
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2893 true, // walk code active on stacks |
|
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2894 NULL, |
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2895 NULL); // SSS: Provide correct closure |
| 0 | 2896 |
| 2897 // Now mark from the roots | |
| 2898 MarkFromRootsClosure markFromRootsClosure(this, _span, | |
|
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2899 verification_mark_bm(), verification_mark_stack(), |
| 0 | 2900 false /* don't yield */, true /* verifying */); |
| 2901 assert(_restart_addr == NULL, "Expected pre-condition"); | |
| 2902 verification_mark_bm()->iterate(&markFromRootsClosure); | |
| 2903 while (_restart_addr != NULL) { | |
| 2904 // Deal with stack overflow: by restarting at the indicated | |
| 2905 // address. | |
| 2906 HeapWord* ra = _restart_addr; | |
| 2907 markFromRootsClosure.reset(ra); | |
| 2908 _restart_addr = NULL; | |
| 2909 verification_mark_bm()->iterate(&markFromRootsClosure, ra, _span.end()); | |
| 2910 } | |
| 2911 assert(verification_mark_stack()->isEmpty(), "Should have been drained"); | |
| 2912 verify_work_stacks_empty(); | |
| 2913 | |
| 2914 // Marking completed -- now verify that each bit marked in | |
| 2915 // verification_mark_bm() is also marked in markBitMap(); flag all | |
| 2916 // errors by printing corresponding objects. | |
| 2917 VerifyMarkedClosure vcl(markBitMap()); | |
| 2918 verification_mark_bm()->iterate(&vcl); | |
| 2919 if (vcl.failed()) { | |
| 2920 gclog_or_tty->print("Verification failed"); | |
|
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2921 Universe::heap()->print_on(gclog_or_tty); |
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2922 fatal("CMS: failed marking verification after remark"); |
| 0 | 2923 } |
| 2924 } | |
| 2925 | |
|
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2926 class VerifyKlassOopsKlassClosure : public KlassClosure { |
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2927 class VerifyKlassOopsClosure : public OopClosure { |
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2928 CMSBitMap* _bitmap; |
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2929 public: |
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2930 VerifyKlassOopsClosure(CMSBitMap* bitmap) : _bitmap(bitmap) { } |
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2931 void do_oop(oop* p) { guarantee(*p == NULL || _bitmap->isMarked((HeapWord*) *p), "Should be marked"); } |
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2932 void do_oop(narrowOop* p) { ShouldNotReachHere(); } |
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2933 } _oop_closure; |
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2934 public: |
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2935 VerifyKlassOopsKlassClosure(CMSBitMap* bitmap) : _oop_closure(bitmap) {} |
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2936 void do_klass(Klass* k) { |
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2937 k->oops_do(&_oop_closure); |
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2938 } |
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2939 }; |
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2940 |
| 0 | 2941 void CMSCollector::verify_after_remark_work_2() { |
| 2942 ResourceMark rm; | |
| 2943 HandleMark hm; | |
| 2944 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 2945 | |
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2946 // Get a clear set of claim bits for the strong roots processing to work with. |
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2947 ClassLoaderDataGraph::clear_claimed_marks(); |
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2948 |
| 0 | 2949 // Mark from roots one level into CMS |
| 2950 MarkRefsIntoVerifyClosure notOlder(_span, verification_mark_bm(), | |
|
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2951 markBitMap()); |
|
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2952 CMKlassClosure klass_closure(¬Older); |
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2953 |
| 0 | 2954 gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel. |
| 2955 gch->gen_process_strong_roots(_cmsGen->level(), | |
| 2956 true, // younger gens are roots | |
|
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2957 true, // activate StrongRootsScope |
|
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2958 false, // not scavenging |
| 0 | 2959 SharedHeap::ScanningOption(roots_scanning_options()), |
|
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2960 ¬Older, |
|
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2961 true, // walk code active on stacks |
|
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2962 NULL, |
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|
2963 &klass_closure); |
| 0 | 2964 |
| 2965 // Now mark from the roots | |
| 2966 MarkFromRootsVerifyClosure markFromRootsClosure(this, _span, | |
| 2967 verification_mark_bm(), markBitMap(), verification_mark_stack()); | |
| 2968 assert(_restart_addr == NULL, "Expected pre-condition"); | |
| 2969 verification_mark_bm()->iterate(&markFromRootsClosure); | |
| 2970 while (_restart_addr != NULL) { | |
| 2971 // Deal with stack overflow: by restarting at the indicated | |
| 2972 // address. | |
| 2973 HeapWord* ra = _restart_addr; | |
| 2974 markFromRootsClosure.reset(ra); | |
| 2975 _restart_addr = NULL; | |
| 2976 verification_mark_bm()->iterate(&markFromRootsClosure, ra, _span.end()); | |
| 2977 } | |
| 2978 assert(verification_mark_stack()->isEmpty(), "Should have been drained"); | |
| 2979 verify_work_stacks_empty(); | |
|
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2980 |
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2981 VerifyKlassOopsKlassClosure verify_klass_oops(verification_mark_bm()); |
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2982 ClassLoaderDataGraph::classes_do(&verify_klass_oops); |
| 0 | 2983 |
| 2984 // Marking completed -- now verify that each bit marked in | |
| 2985 // verification_mark_bm() is also marked in markBitMap(); flag all | |
| 2986 // errors by printing corresponding objects. | |
| 2987 VerifyMarkedClosure vcl(markBitMap()); | |
| 2988 verification_mark_bm()->iterate(&vcl); | |
| 2989 assert(!vcl.failed(), "Else verification above should not have succeeded"); | |
| 2990 } | |
| 2991 | |
| 2992 void ConcurrentMarkSweepGeneration::save_marks() { | |
| 2993 // delegate to CMS space | |
| 2994 cmsSpace()->save_marks(); | |
| 2995 for (uint i = 0; i < ParallelGCThreads; i++) { | |
| 2996 _par_gc_thread_states[i]->promo.startTrackingPromotions(); | |
| 2997 } | |
| 2998 } | |
| 2999 | |
| 3000 bool ConcurrentMarkSweepGeneration::no_allocs_since_save_marks() { | |
| 3001 return cmsSpace()->no_allocs_since_save_marks(); | |
| 3002 } | |
| 3003 | |
| 3004 #define CMS_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \ | |
| 3005 \ | |
| 3006 void ConcurrentMarkSweepGeneration:: \ | |
| 3007 oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) { \ | |
| 3008 cl->set_generation(this); \ | |
| 3009 cmsSpace()->oop_since_save_marks_iterate##nv_suffix(cl); \ | |
| 3010 cl->reset_generation(); \ | |
| 3011 save_marks(); \ | |
| 3012 } | |
| 3013 | |
| 3014 ALL_SINCE_SAVE_MARKS_CLOSURES(CMS_SINCE_SAVE_MARKS_DEFN) | |
| 3015 | |
| 3016 void | |
| 3017 ConcurrentMarkSweepGeneration::object_iterate_since_last_GC(ObjectClosure* blk) | |
| 3018 { | |
| 3019 // Not currently implemented; need to do the following. -- ysr. | |
| 3020 // dld -- I think that is used for some sort of allocation profiler. So it | |
| 3021 // really means the objects allocated by the mutator since the last | |
| 3022 // GC. We could potentially implement this cheaply by recording only | |
| 3023 // the direct allocations in a side data structure. | |
| 3024 // | |
| 3025 // I think we probably ought not to be required to support these | |
| 3026 // iterations at any arbitrary point; I think there ought to be some | |
| 3027 // call to enable/disable allocation profiling in a generation/space, | |
| 3028 // and the iterator ought to return the objects allocated in the | |
| 3029 // gen/space since the enable call, or the last iterator call (which | |
| 3030 // will probably be at a GC.) That way, for gens like CM&S that would | |
| 3031 // require some extra data structure to support this, we only pay the | |
| 3032 // cost when it's in use... | |
| 3033 cmsSpace()->object_iterate_since_last_GC(blk); | |
| 3034 } | |
| 3035 | |
| 3036 void | |
| 3037 ConcurrentMarkSweepGeneration::younger_refs_iterate(OopsInGenClosure* cl) { | |
| 3038 cl->set_generation(this); | |
| 3039 younger_refs_in_space_iterate(_cmsSpace, cl); | |
| 3040 cl->reset_generation(); | |
| 3041 } | |
| 3042 | |
| 3043 void | |
|
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3044 ConcurrentMarkSweepGeneration::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) { |
| 0 | 3045 if (freelistLock()->owned_by_self()) { |
| 3046 Generation::oop_iterate(mr, cl); | |
| 3047 } else { | |
| 3048 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 3049 Generation::oop_iterate(mr, cl); | |
| 3050 } | |
| 3051 } | |
| 3052 | |
| 3053 void | |
|
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3054 ConcurrentMarkSweepGeneration::oop_iterate(ExtendedOopClosure* cl) { |
| 0 | 3055 if (freelistLock()->owned_by_self()) { |
| 3056 Generation::oop_iterate(cl); | |
| 3057 } else { | |
| 3058 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 3059 Generation::oop_iterate(cl); | |
| 3060 } | |
| 3061 } | |
| 3062 | |
| 3063 void | |
| 3064 ConcurrentMarkSweepGeneration::object_iterate(ObjectClosure* cl) { | |
| 3065 if (freelistLock()->owned_by_self()) { | |
| 3066 Generation::object_iterate(cl); | |
| 3067 } else { | |
| 3068 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 3069 Generation::object_iterate(cl); | |
| 3070 } | |
| 3071 } | |
| 3072 | |
| 3073 void | |
|
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3074 ConcurrentMarkSweepGeneration::safe_object_iterate(ObjectClosure* cl) { |
|
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3075 if (freelistLock()->owned_by_self()) { |
|
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3076 Generation::safe_object_iterate(cl); |
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3077 } else { |
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3078 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); |
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3079 Generation::safe_object_iterate(cl); |
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3080 } |
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3081 } |
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3082 |
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3083 void |
| 0 | 3084 ConcurrentMarkSweepGeneration::post_compact() { |
| 3085 } | |
| 3086 | |
| 3087 void | |
| 3088 ConcurrentMarkSweepGeneration::prepare_for_verify() { | |
| 3089 // Fix the linear allocation blocks to look like free blocks. | |
| 3090 | |
| 3091 // Locks are normally acquired/released in gc_prologue/gc_epilogue, but those | |
| 3092 // are not called when the heap is verified during universe initialization and | |
| 3093 // at vm shutdown. | |
| 3094 if (freelistLock()->owned_by_self()) { | |
| 3095 cmsSpace()->prepare_for_verify(); | |
| 3096 } else { | |
| 3097 MutexLockerEx fll(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 3098 cmsSpace()->prepare_for_verify(); | |
| 3099 } | |
| 3100 } | |
| 3101 | |
| 3102 void | |
| 6008 | 3103 ConcurrentMarkSweepGeneration::verify() { |
| 0 | 3104 // Locks are normally acquired/released in gc_prologue/gc_epilogue, but those |
| 3105 // are not called when the heap is verified during universe initialization and | |
| 3106 // at vm shutdown. | |
| 3107 if (freelistLock()->owned_by_self()) { | |
| 6008 | 3108 cmsSpace()->verify(); |
| 0 | 3109 } else { |
| 3110 MutexLockerEx fll(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 6008 | 3111 cmsSpace()->verify(); |
| 3112 } | |
| 3113 } | |
| 3114 | |
| 3115 void CMSCollector::verify() { | |
| 3116 _cmsGen->verify(); | |
| 0 | 3117 } |
| 3118 | |
| 3119 #ifndef PRODUCT | |
| 3120 bool CMSCollector::overflow_list_is_empty() const { | |
| 3121 assert(_num_par_pushes >= 0, "Inconsistency"); | |
| 3122 if (_overflow_list == NULL) { | |
| 3123 assert(_num_par_pushes == 0, "Inconsistency"); | |
| 3124 } | |
| 3125 return _overflow_list == NULL; | |
| 3126 } | |
| 3127 | |
| 3128 // The methods verify_work_stacks_empty() and verify_overflow_empty() | |
| 3129 // merely consolidate assertion checks that appear to occur together frequently. | |
| 3130 void CMSCollector::verify_work_stacks_empty() const { | |
| 3131 assert(_markStack.isEmpty(), "Marking stack should be empty"); | |
| 3132 assert(overflow_list_is_empty(), "Overflow list should be empty"); | |
| 3133 } | |
| 3134 | |
| 3135 void CMSCollector::verify_overflow_empty() const { | |
| 3136 assert(overflow_list_is_empty(), "Overflow list should be empty"); | |
| 3137 assert(no_preserved_marks(), "No preserved marks"); | |
| 3138 } | |
| 3139 #endif // PRODUCT | |
| 3140 | |
|
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3141 // Decide if we want to enable class unloading as part of the |
|
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3142 // ensuing concurrent GC cycle. We will collect and |
|
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3143 // unload classes if it's the case that: |
|
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3144 // (1) an explicit gc request has been made and the flag |
|
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3145 // ExplicitGCInvokesConcurrentAndUnloadsClasses is set, OR |
|
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3146 // (2) (a) class unloading is enabled at the command line, and |
|
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3147 // (b) old gen is getting really full |
|
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3148 // NOTE: Provided there is no change in the state of the heap between |
|
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3149 // calls to this method, it should have idempotent results. Moreover, |
|
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3150 // its results should be monotonically increasing (i.e. going from 0 to 1, |
|
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3151 // but not 1 to 0) between successive calls between which the heap was |
|
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3152 // not collected. For the implementation below, it must thus rely on |
|
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3153 // the property that concurrent_cycles_since_last_unload() |
|
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3154 // will not decrease unless a collection cycle happened and that |
|
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3155 // _cmsGen->is_too_full() are |
|
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3156 // themselves also monotonic in that sense. See check_monotonicity() |
|
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3157 // below. |
|
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3158 void CMSCollector::update_should_unload_classes() { |
|
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3159 _should_unload_classes = false; |
|
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3160 // Condition 1 above |
|
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|
3161 if (_full_gc_requested && ExplicitGCInvokesConcurrentAndUnloadsClasses) { |
|
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3162 _should_unload_classes = true; |
|
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|
3163 } else if (CMSClassUnloadingEnabled) { // Condition 2.a above |
|
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3164 // Disjuncts 2.b.(i,ii,iii) above |
|
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3165 _should_unload_classes = (concurrent_cycles_since_last_unload() >= |
|
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|
3166 CMSClassUnloadingMaxInterval) |
|
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3167 || _cmsGen->is_too_full(); |
|
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3168 } |
|
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|
3169 } |
|
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|
3170 |
|
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|
3171 bool ConcurrentMarkSweepGeneration::is_too_full() const { |
|
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3172 bool res = should_concurrent_collect(); |
|
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3173 res = res && (occupancy() > (double)CMSIsTooFullPercentage/100.0); |
|
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3174 return res; |
|
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3175 } |
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3176 |
| 0 | 3177 void CMSCollector::setup_cms_unloading_and_verification_state() { |
|
3293
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3178 const bool should_verify = VerifyBeforeGC || VerifyAfterGC || VerifyDuringGC |
| 0 | 3179 || VerifyBeforeExit; |
|
3293
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3180 const int rso = SharedHeap::SO_Strings | SharedHeap::SO_CodeCache; |
| 0 | 3181 |
|
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|
3182 if (should_unload_classes()) { // Should unload classes this cycle |
| 0 | 3183 remove_root_scanning_option(rso); // Shrink the root set appropriately |
| 3184 set_verifying(should_verify); // Set verification state for this cycle | |
| 3185 return; // Nothing else needs to be done at this time | |
| 3186 } | |
| 3187 | |
| 3188 // Not unloading classes this cycle | |
|
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3189 assert(!should_unload_classes(), "Inconsitency!"); |
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|
3190 if ((!verifying() || unloaded_classes_last_cycle()) && should_verify) { |
| 0 | 3191 // Include symbols, strings and code cache elements to prevent their resurrection. |
| 3192 add_root_scanning_option(rso); | |
| 3193 set_verifying(true); | |
| 3194 } else if (verifying() && !should_verify) { | |
| 3195 // We were verifying, but some verification flags got disabled. | |
| 3196 set_verifying(false); | |
| 3197 // Exclude symbols, strings and code cache elements from root scanning to | |
| 3198 // reduce IM and RM pauses. | |
| 3199 remove_root_scanning_option(rso); | |
| 3200 } | |
| 3201 } | |
| 3202 | |
| 3203 | |
| 3204 #ifndef PRODUCT | |
| 3205 HeapWord* CMSCollector::block_start(const void* p) const { | |
| 3206 const HeapWord* addr = (HeapWord*)p; | |
| 3207 if (_span.contains(p)) { | |
| 3208 if (_cmsGen->cmsSpace()->is_in_reserved(addr)) { | |
| 3209 return _cmsGen->cmsSpace()->block_start(p); | |
| 3210 } | |
| 3211 } | |
| 3212 return NULL; | |
| 3213 } | |
| 3214 #endif | |
| 3215 | |
| 3216 HeapWord* | |
| 3217 ConcurrentMarkSweepGeneration::expand_and_allocate(size_t word_size, | |
| 3218 bool tlab, | |
| 3219 bool parallel) { | |
|
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3220 CMSSynchronousYieldRequest yr; |
| 0 | 3221 assert(!tlab, "Can't deal with TLAB allocation"); |
| 3222 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
| 3223 expand(word_size*HeapWordSize, MinHeapDeltaBytes, | |
| 3224 CMSExpansionCause::_satisfy_allocation); | |
| 3225 if (GCExpandToAllocateDelayMillis > 0) { | |
| 3226 os::sleep(Thread::current(), GCExpandToAllocateDelayMillis, false); | |
| 3227 } | |
|
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3228 return have_lock_and_allocate(word_size, tlab); |
| 0 | 3229 } |
| 3230 | |
| 3231 // YSR: All of this generation expansion/shrinking stuff is an exact copy of | |
| 3232 // OneContigSpaceCardGeneration, which makes me wonder if we should move this | |
| 3233 // to CardGeneration and share it... | |
|
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3234 bool ConcurrentMarkSweepGeneration::expand(size_t bytes, size_t expand_bytes) { |
|
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3235 return CardGeneration::expand(bytes, expand_bytes); |
|
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3236 } |
|
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3237 |
| 0 | 3238 void ConcurrentMarkSweepGeneration::expand(size_t bytes, size_t expand_bytes, |
| 3239 CMSExpansionCause::Cause cause) | |
| 3240 { | |
|
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3241 |
|
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3242 bool success = expand(bytes, expand_bytes); |
|
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3243 |
| 0 | 3244 // remember why we expanded; this information is used |
| 3245 // by shouldConcurrentCollect() when making decisions on whether to start | |
| 3246 // a new CMS cycle. | |
| 3247 if (success) { | |
| 3248 set_expansion_cause(cause); | |
| 3249 if (PrintGCDetails && Verbose) { | |
| 3250 gclog_or_tty->print_cr("Expanded CMS gen for %s", | |
| 3251 CMSExpansionCause::to_string(cause)); | |
| 3252 } | |
| 3253 } | |
| 3254 } | |
| 3255 | |
| 3256 HeapWord* ConcurrentMarkSweepGeneration::expand_and_par_lab_allocate(CMSParGCThreadState* ps, size_t word_sz) { | |
| 3257 HeapWord* res = NULL; | |
| 3258 MutexLocker x(ParGCRareEvent_lock); | |
| 3259 while (true) { | |
| 3260 // Expansion by some other thread might make alloc OK now: | |
| 3261 res = ps->lab.alloc(word_sz); | |
| 3262 if (res != NULL) return res; | |
| 3263 // If there's not enough expansion space available, give up. | |
| 3264 if (_virtual_space.uncommitted_size() < (word_sz * HeapWordSize)) { | |
| 3265 return NULL; | |
| 3266 } | |
| 3267 // Otherwise, we try expansion. | |
| 3268 expand(word_sz*HeapWordSize, MinHeapDeltaBytes, | |
| 3269 CMSExpansionCause::_allocate_par_lab); | |
| 3270 // Now go around the loop and try alloc again; | |
| 3271 // A competing par_promote might beat us to the expansion space, | |
| 3272 // so we may go around the loop again if promotion fails agaion. | |
| 3273 if (GCExpandToAllocateDelayMillis > 0) { | |
| 3274 os::sleep(Thread::current(), GCExpandToAllocateDelayMillis, false); | |
| 3275 } | |
| 3276 } | |
| 3277 } | |
| 3278 | |
| 3279 | |
| 3280 bool ConcurrentMarkSweepGeneration::expand_and_ensure_spooling_space( | |
| 3281 PromotionInfo* promo) { | |
| 3282 MutexLocker x(ParGCRareEvent_lock); | |
| 3283 size_t refill_size_bytes = promo->refillSize() * HeapWordSize; | |
| 3284 while (true) { | |
| 3285 // Expansion by some other thread might make alloc OK now: | |
| 3286 if (promo->ensure_spooling_space()) { | |
| 3287 assert(promo->has_spooling_space(), | |
| 3288 "Post-condition of successful ensure_spooling_space()"); | |
| 3289 return true; | |
| 3290 } | |
| 3291 // If there's not enough expansion space available, give up. | |
| 3292 if (_virtual_space.uncommitted_size() < refill_size_bytes) { | |
| 3293 return false; | |
| 3294 } | |
| 3295 // Otherwise, we try expansion. | |
| 3296 expand(refill_size_bytes, MinHeapDeltaBytes, | |
| 3297 CMSExpansionCause::_allocate_par_spooling_space); | |
| 3298 // Now go around the loop and try alloc again; | |
| 3299 // A competing allocation might beat us to the expansion space, | |
| 3300 // so we may go around the loop again if allocation fails again. | |
| 3301 if (GCExpandToAllocateDelayMillis > 0) { | |
| 3302 os::sleep(Thread::current(), GCExpandToAllocateDelayMillis, false); | |
| 3303 } | |
| 3304 } | |
| 3305 } | |
| 3306 | |
| 3307 | |
| 3308 | |
| 3309 void ConcurrentMarkSweepGeneration::shrink(size_t bytes) { | |
| 3310 assert_locked_or_safepoint(Heap_lock); | |
| 3311 size_t size = ReservedSpace::page_align_size_down(bytes); | |
| 3312 if (size > 0) { | |
| 3313 shrink_by(size); | |
| 3314 } | |
| 3315 } | |
| 3316 | |
| 3317 bool ConcurrentMarkSweepGeneration::grow_by(size_t bytes) { | |
| 3318 assert_locked_or_safepoint(Heap_lock); | |
| 3319 bool result = _virtual_space.expand_by(bytes); | |
| 3320 if (result) { | |
| 3321 HeapWord* old_end = _cmsSpace->end(); | |
| 3322 size_t new_word_size = | |
| 3323 heap_word_size(_virtual_space.committed_size()); | |
| 3324 MemRegion mr(_cmsSpace->bottom(), new_word_size); | |
| 3325 _bts->resize(new_word_size); // resize the block offset shared array | |
| 3326 Universe::heap()->barrier_set()->resize_covered_region(mr); | |
| 3327 // Hmmmm... why doesn't CFLS::set_end verify locking? | |
| 3328 // This is quite ugly; FIX ME XXX | |
|
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3329 _cmsSpace->assert_locked(freelistLock()); |
| 0 | 3330 _cmsSpace->set_end((HeapWord*)_virtual_space.high()); |
| 3331 | |
| 3332 // update the space and generation capacity counters | |
| 3333 if (UsePerfData) { | |
| 3334 _space_counters->update_capacity(); | |
| 3335 _gen_counters->update_all(); | |
| 3336 } | |
| 3337 | |
| 3338 if (Verbose && PrintGC) { | |
| 3339 size_t new_mem_size = _virtual_space.committed_size(); | |
| 3340 size_t old_mem_size = new_mem_size - bytes; | |
| 3341 gclog_or_tty->print_cr("Expanding %s from %ldK by %ldK to %ldK", | |
| 3342 name(), old_mem_size/K, bytes/K, new_mem_size/K); | |
| 3343 } | |
| 3344 } | |
| 3345 return result; | |
| 3346 } | |
| 3347 | |
| 3348 bool ConcurrentMarkSweepGeneration::grow_to_reserved() { | |
| 3349 assert_locked_or_safepoint(Heap_lock); | |
| 3350 bool success = true; | |
| 3351 const size_t remaining_bytes = _virtual_space.uncommitted_size(); | |
| 3352 if (remaining_bytes > 0) { | |
| 3353 success = grow_by(remaining_bytes); | |
| 3354 DEBUG_ONLY(if (!success) warning("grow to reserved failed");) | |
| 3355 } | |
| 3356 return success; | |
| 3357 } | |
| 3358 | |
| 3359 void ConcurrentMarkSweepGeneration::shrink_by(size_t bytes) { | |
| 3360 assert_locked_or_safepoint(Heap_lock); | |
| 3361 assert_lock_strong(freelistLock()); | |
| 3362 // XXX Fix when compaction is implemented. | |
| 3363 warning("Shrinking of CMS not yet implemented"); | |
| 3364 return; | |
| 3365 } | |
| 3366 | |
| 3367 | |
| 3368 // Simple ctor/dtor wrapper for accounting & timer chores around concurrent | |
| 3369 // phases. | |
| 3370 class CMSPhaseAccounting: public StackObj { | |
| 3371 public: | |
| 3372 CMSPhaseAccounting(CMSCollector *collector, | |
| 3373 const char *phase, | |
| 3374 bool print_cr = true); | |
| 3375 ~CMSPhaseAccounting(); | |
| 3376 | |
| 3377 private: | |
| 3378 CMSCollector *_collector; | |
| 3379 const char *_phase; | |
| 3380 elapsedTimer _wallclock; | |
| 3381 bool _print_cr; | |
| 3382 | |
| 3383 public: | |
| 3384 // Not MT-safe; so do not pass around these StackObj's | |
| 3385 // where they may be accessed by other threads. | |
| 3386 jlong wallclock_millis() { | |
| 3387 assert(_wallclock.is_active(), "Wall clock should not stop"); | |
| 3388 _wallclock.stop(); // to record time | |
| 3389 jlong ret = _wallclock.milliseconds(); | |
| 3390 _wallclock.start(); // restart | |
| 3391 return ret; | |
| 3392 } | |
| 3393 }; | |
| 3394 | |
| 3395 CMSPhaseAccounting::CMSPhaseAccounting(CMSCollector *collector, | |
| 3396 const char *phase, | |
| 3397 bool print_cr) : | |
| 3398 _collector(collector), _phase(phase), _print_cr(print_cr) { | |
| 3399 | |
| 3400 if (PrintCMSStatistics != 0) { | |
| 3401 _collector->resetYields(); | |
| 3402 } | |
| 3403 if (PrintGCDetails && PrintGCTimeStamps) { | |
| 3404 gclog_or_tty->date_stamp(PrintGCDateStamps); | |
| 3405 gclog_or_tty->stamp(); | |
| 3406 gclog_or_tty->print_cr(": [%s-concurrent-%s-start]", | |
| 3407 _collector->cmsGen()->short_name(), _phase); | |
| 3408 } | |
| 3409 _collector->resetTimer(); | |
| 3410 _wallclock.start(); | |
| 3411 _collector->startTimer(); | |
| 3412 } | |
| 3413 | |
| 3414 CMSPhaseAccounting::~CMSPhaseAccounting() { | |
| 3415 assert(_wallclock.is_active(), "Wall clock should not have stopped"); | |
| 3416 _collector->stopTimer(); | |
| 3417 _wallclock.stop(); | |
| 3418 if (PrintGCDetails) { | |
| 3419 gclog_or_tty->date_stamp(PrintGCDateStamps); | |
|
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|
3420 gclog_or_tty->stamp(PrintGCTimeStamps); |
| 0 | 3421 gclog_or_tty->print("[%s-concurrent-%s: %3.3f/%3.3f secs]", |
| 3422 _collector->cmsGen()->short_name(), | |
| 3423 _phase, _collector->timerValue(), _wallclock.seconds()); | |
| 3424 if (_print_cr) { | |
| 3425 gclog_or_tty->print_cr(""); | |
| 3426 } | |
| 3427 if (PrintCMSStatistics != 0) { | |
| 3428 gclog_or_tty->print_cr(" (CMS-concurrent-%s yielded %d times)", _phase, | |
| 3429 _collector->yields()); | |
| 3430 } | |
| 3431 } | |
| 3432 } | |
| 3433 | |
| 3434 // CMS work | |
| 3435 | |
| 3436 // Checkpoint the roots into this generation from outside | |
| 3437 // this generation. [Note this initial checkpoint need only | |
| 3438 // be approximate -- we'll do a catch up phase subsequently.] | |
| 3439 void CMSCollector::checkpointRootsInitial(bool asynch) { | |
| 3440 assert(_collectorState == InitialMarking, "Wrong collector state"); | |
| 3441 check_correct_thread_executing(); | |
|
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|
3442 TraceCMSMemoryManagerStats tms(_collectorState,GenCollectedHeap::heap()->gc_cause()); |
|
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|
3443 |
| 0 | 3444 ReferenceProcessor* rp = ref_processor(); |
| 3445 SpecializationStats::clear(); | |
| 3446 assert(_restart_addr == NULL, "Control point invariant"); | |
| 3447 if (asynch) { | |
| 3448 // acquire locks for subsequent manipulations | |
| 3449 MutexLockerEx x(bitMapLock(), | |
| 3450 Mutex::_no_safepoint_check_flag); | |
| 3451 checkpointRootsInitialWork(asynch); | |
|
3979
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|
3452 // enable ("weak") refs discovery |
|
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|
3453 rp->enable_discovery(true /*verify_disabled*/, true /*check_no_refs*/); |
| 0 | 3454 _collectorState = Marking; |
| 3455 } else { | |
| 3456 // (Weak) Refs discovery: this is controlled from genCollectedHeap::do_collection | |
| 3457 // which recognizes if we are a CMS generation, and doesn't try to turn on | |
| 3458 // discovery; verify that they aren't meddling. | |
| 3459 assert(!rp->discovery_is_atomic(), | |
| 3460 "incorrect setting of discovery predicate"); | |
| 3461 assert(!rp->discovery_enabled(), "genCollectedHeap shouldn't control " | |
| 3462 "ref discovery for this generation kind"); | |
| 3463 // already have locks | |
| 3464 checkpointRootsInitialWork(asynch); | |
|
3979
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|
3465 // now enable ("weak") refs discovery |
|
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|
3466 rp->enable_discovery(true /*verify_disabled*/, false /*verify_no_refs*/); |
| 0 | 3467 _collectorState = Marking; |
| 3468 } | |
| 3469 SpecializationStats::print(); | |
| 3470 } | |
| 3471 | |
| 3472 void CMSCollector::checkpointRootsInitialWork(bool asynch) { | |
| 3473 assert(SafepointSynchronize::is_at_safepoint(), "world should be stopped"); | |
| 3474 assert(_collectorState == InitialMarking, "just checking"); | |
| 3475 | |
| 3476 // If there has not been a GC[n-1] since last GC[n] cycle completed, | |
| 3477 // precede our marking with a collection of all | |
| 3478 // younger generations to keep floating garbage to a minimum. | |
| 3479 // XXX: we won't do this for now -- it's an optimization to be done later. | |
| 3480 | |
| 3481 // already have locks | |
| 3482 assert_lock_strong(bitMapLock()); | |
| 3483 assert(_markBitMap.isAllClear(), "was reset at end of previous cycle"); | |
| 3484 | |
| 3485 // Setup the verification and class unloading state for this | |
| 3486 // CMS collection cycle. | |
| 3487 setup_cms_unloading_and_verification_state(); | |
| 3488 | |
| 3489 NOT_PRODUCT(TraceTime t("\ncheckpointRootsInitialWork", | |
| 3490 PrintGCDetails && Verbose, true, gclog_or_tty);) | |
| 3491 if (UseAdaptiveSizePolicy) { | |
| 3492 size_policy()->checkpoint_roots_initial_begin(); | |
| 3493 } | |
| 3494 | |
| 3495 // Reset all the PLAB chunk arrays if necessary. | |
| 3496 if (_survivor_plab_array != NULL && !CMSPLABRecordAlways) { | |
| 3497 reset_survivor_plab_arrays(); | |
| 3498 } | |
| 3499 | |
| 3500 ResourceMark rm; | |
| 3501 HandleMark hm; | |
| 3502 | |
| 3503 FalseClosure falseClosure; | |
| 3504 // In the case of a synchronous collection, we will elide the | |
| 3505 // remark step, so it's important to catch all the nmethod oops | |
|
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|
3506 // in this step. |
|
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|
3507 // The final 'true' flag to gen_process_strong_roots will ensure this. |
|
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|
3508 // If 'async' is true, we can relax the nmethod tracing. |
|
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|
3509 MarkRefsIntoClosure notOlder(_span, &_markBitMap); |
| 0 | 3510 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
| 3511 | |
| 3512 verify_work_stacks_empty(); | |
| 3513 verify_overflow_empty(); | |
| 3514 | |
| 3515 gch->ensure_parsability(false); // fill TLABs, but no need to retire them | |
| 3516 // Update the saved marks which may affect the root scans. | |
| 3517 gch->save_marks(); | |
| 3518 | |
| 3519 // weak reference processing has not started yet. | |
| 3520 ref_processor()->set_enqueuing_is_done(false); | |
| 3521 | |
|
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3522 // Need to remember all newly created CLDs, |
|
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3523 // so that we can guarantee that the remark finds them. |
|
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|
3524 ClassLoaderDataGraph::remember_new_clds(true); |
|
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|
3525 |
|
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|
3526 // Whenever a CLD is found, it will be claimed before proceeding to mark |
|
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3527 // the klasses. The claimed marks need to be cleared before marking starts. |
|
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|
3528 ClassLoaderDataGraph::clear_claimed_marks(); |
|
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3529 |
|
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|
3530 CMKlassClosure klass_closure(¬Older); |
| 0 | 3531 { |
| 3532 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact;) | |
| 3533 gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel. | |
| 3534 gch->gen_process_strong_roots(_cmsGen->level(), | |
| 3535 true, // younger gens are roots | |
|
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|
3536 true, // activate StrongRootsScope |
|
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|
3537 false, // not scavenging |
| 0 | 3538 SharedHeap::ScanningOption(roots_scanning_options()), |
|
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|
3539 ¬Older, |
|
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|
3540 true, // walk all of code cache if (so & SO_CodeCache) |
|
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|
3541 NULL, |
|
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|
3542 &klass_closure); |
| 0 | 3543 } |
| 3544 | |
| 3545 // Clear mod-union table; it will be dirtied in the prologue of | |
| 3546 // CMS generation per each younger generation collection. | |
| 3547 | |
| 3548 assert(_modUnionTable.isAllClear(), | |
| 3549 "Was cleared in most recent final checkpoint phase" | |
| 3550 " or no bits are set in the gc_prologue before the start of the next " | |
| 3551 "subsequent marking phase."); | |
| 3552 | |
|
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|
3553 assert(_ct->klass_rem_set()->mod_union_is_clear(), "Must be"); |
|
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|
3554 |
| 0 | 3555 // Save the end of the used_region of the constituent generations |
| 3556 // to be used to limit the extent of sweep in each generation. | |
| 3557 save_sweep_limits(); | |
| 3558 if (UseAdaptiveSizePolicy) { | |
| 3559 size_policy()->checkpoint_roots_initial_end(gch->gc_cause()); | |
| 3560 } | |
| 3561 verify_overflow_empty(); | |
| 3562 } | |
| 3563 | |
| 3564 bool CMSCollector::markFromRoots(bool asynch) { | |
| 3565 // we might be tempted to assert that: | |
| 3566 // assert(asynch == !SafepointSynchronize::is_at_safepoint(), | |
| 3567 // "inconsistent argument?"); | |
| 3568 // However that wouldn't be right, because it's possible that | |
| 3569 // a safepoint is indeed in progress as a younger generation | |
| 3570 // stop-the-world GC happens even as we mark in this generation. | |
| 3571 assert(_collectorState == Marking, "inconsistent state?"); | |
| 3572 check_correct_thread_executing(); | |
| 3573 verify_overflow_empty(); | |
| 3574 | |
| 3575 bool res; | |
| 3576 if (asynch) { | |
| 3577 | |
| 3578 // Start the timers for adaptive size policy for the concurrent phases | |
| 3579 // Do it here so that the foreground MS can use the concurrent | |
| 3580 // timer since a foreground MS might has the sweep done concurrently | |
| 3581 // or STW. | |
| 3582 if (UseAdaptiveSizePolicy) { | |
| 3583 size_policy()->concurrent_marking_begin(); | |
| 3584 } | |
| 3585 | |
| 3586 // Weak ref discovery note: We may be discovering weak | |
| 3587 // refs in this generation concurrent (but interleaved) with | |
| 3588 // weak ref discovery by a younger generation collector. | |
| 3589 | |
| 3590 CMSTokenSyncWithLocks ts(true, bitMapLock()); | |
| 3591 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
| 3592 CMSPhaseAccounting pa(this, "mark", !PrintGCDetails); | |
| 3593 res = markFromRootsWork(asynch); | |
| 3594 if (res) { | |
| 3595 _collectorState = Precleaning; | |
| 3596 } else { // We failed and a foreground collection wants to take over | |
| 3597 assert(_foregroundGCIsActive, "internal state inconsistency"); | |
| 3598 assert(_restart_addr == NULL, "foreground will restart from scratch"); | |
| 3599 if (PrintGCDetails) { | |
| 3600 gclog_or_tty->print_cr("bailing out to foreground collection"); | |
| 3601 } | |
| 3602 } | |
| 3603 if (UseAdaptiveSizePolicy) { | |
| 3604 size_policy()->concurrent_marking_end(); | |
| 3605 } | |
| 3606 } else { | |
| 3607 assert(SafepointSynchronize::is_at_safepoint(), | |
| 3608 "inconsistent with asynch == false"); | |
| 3609 if (UseAdaptiveSizePolicy) { | |
| 3610 size_policy()->ms_collection_marking_begin(); | |
| 3611 } | |
| 3612 // already have locks | |
| 3613 res = markFromRootsWork(asynch); | |
| 3614 _collectorState = FinalMarking; | |
| 3615 if (UseAdaptiveSizePolicy) { | |
| 3616 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 3617 size_policy()->ms_collection_marking_end(gch->gc_cause()); | |
| 3618 } | |
| 3619 } | |
| 3620 verify_overflow_empty(); | |
| 3621 return res; | |
| 3622 } | |
| 3623 | |
| 3624 bool CMSCollector::markFromRootsWork(bool asynch) { | |
| 3625 // iterate over marked bits in bit map, doing a full scan and mark | |
| 3626 // from these roots using the following algorithm: | |
| 3627 // . if oop is to the right of the current scan pointer, | |
| 3628 // mark corresponding bit (we'll process it later) | |
| 3629 // . else (oop is to left of current scan pointer) | |
| 3630 // push oop on marking stack | |
| 3631 // . drain the marking stack | |
| 3632 | |
| 3633 // Note that when we do a marking step we need to hold the | |
| 3634 // bit map lock -- recall that direct allocation (by mutators) | |
| 3635 // and promotion (by younger generation collectors) is also | |
| 3636 // marking the bit map. [the so-called allocate live policy.] | |
| 3637 // Because the implementation of bit map marking is not | |
| 3638 // robust wrt simultaneous marking of bits in the same word, | |
| 3639 // we need to make sure that there is no such interference | |
| 3640 // between concurrent such updates. | |
| 3641 | |
| 3642 // already have locks | |
| 3643 assert_lock_strong(bitMapLock()); | |
| 3644 | |
| 3645 verify_work_stacks_empty(); | |
| 3646 verify_overflow_empty(); | |
| 3647 bool result = false; | |
| 1284 | 3648 if (CMSConcurrentMTEnabled && ConcGCThreads > 0) { |
| 0 | 3649 result = do_marking_mt(asynch); |
| 3650 } else { | |
| 3651 result = do_marking_st(asynch); | |
| 3652 } | |
| 3653 return result; | |
| 3654 } | |
| 3655 | |
| 3656 // Forward decl | |
| 3657 class CMSConcMarkingTask; | |
| 3658 | |
| 3659 class CMSConcMarkingTerminator: public ParallelTaskTerminator { | |
| 3660 CMSCollector* _collector; | |
| 3661 CMSConcMarkingTask* _task; | |
|
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|
3662 public: |
| 0 | 3663 virtual void yield(); |
|
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|
3664 |
| 0 | 3665 // "n_threads" is the number of threads to be terminated. |
| 3666 // "queue_set" is a set of work queues of other threads. | |
| 3667 // "collector" is the CMS collector associated with this task terminator. | |
| 3668 // "yield" indicates whether we need the gang as a whole to yield. | |
|
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|
3669 CMSConcMarkingTerminator(int n_threads, TaskQueueSetSuper* queue_set, CMSCollector* collector) : |
| 0 | 3670 ParallelTaskTerminator(n_threads, queue_set), |
|
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|
3671 _collector(collector) { } |
|
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|
3672 |
|
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|
3673 void set_task(CMSConcMarkingTask* task) { |
|
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|
3674 _task = task; |
|
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|
3675 } |
|
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|
3676 }; |
|
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|
3677 |
|
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|
3678 class CMSConcMarkingTerminatorTerminator: public TerminatorTerminator { |
|
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|
3679 CMSConcMarkingTask* _task; |
|
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|
3680 public: |
|
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|
3681 bool should_exit_termination(); |
| 0 | 3682 void set_task(CMSConcMarkingTask* task) { |
| 3683 _task = task; | |
| 3684 } | |
| 3685 }; | |
| 3686 | |
| 3687 // MT Concurrent Marking Task | |
| 3688 class CMSConcMarkingTask: public YieldingFlexibleGangTask { | |
| 3689 CMSCollector* _collector; | |
| 3690 int _n_workers; // requested/desired # workers | |
| 3691 bool _asynch; | |
| 3692 bool _result; | |
| 3693 CompactibleFreeListSpace* _cms_space; | |
|
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|
3694 char _pad_front[64]; // padding to ... |
|
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|
3695 HeapWord* _global_finger; // ... avoid sharing cache line |
|
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|
3696 char _pad_back[64]; |
|
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|
3697 HeapWord* _restart_addr; |
| 0 | 3698 |
| 3699 // Exposed here for yielding support | |
| 3700 Mutex* const _bit_map_lock; | |
| 3701 | |
| 3702 // The per thread work queues, available here for stealing | |
| 3703 OopTaskQueueSet* _task_queues; | |
|
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3704 |
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3705 // Termination (and yielding) support |
| 0 | 3706 CMSConcMarkingTerminator _term; |
|
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3707 CMSConcMarkingTerminatorTerminator _term_term; |
| 0 | 3708 |
| 3709 public: | |
| 3710 CMSConcMarkingTask(CMSCollector* collector, | |
| 3711 CompactibleFreeListSpace* cms_space, | |
|
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3712 bool asynch, |
| 0 | 3713 YieldingFlexibleWorkGang* workers, |
| 3714 OopTaskQueueSet* task_queues): | |
| 3715 YieldingFlexibleGangTask("Concurrent marking done multi-threaded"), | |
| 3716 _collector(collector), | |
| 3717 _cms_space(cms_space), | |
|
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3718 _asynch(asynch), _n_workers(0), _result(true), |
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3719 _task_queues(task_queues), |
|
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3720 _term(_n_workers, task_queues, _collector), |
| 0 | 3721 _bit_map_lock(collector->bitMapLock()) |
| 3722 { | |
|
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3723 _requested_size = _n_workers; |
| 0 | 3724 _term.set_task(this); |
|
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3725 _term_term.set_task(this); |
|
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3726 _restart_addr = _global_finger = _cms_space->bottom(); |
| 0 | 3727 } |
| 3728 | |
| 3729 | |
| 3730 OopTaskQueueSet* task_queues() { return _task_queues; } | |
| 3731 | |
| 3732 OopTaskQueue* work_queue(int i) { return task_queues()->queue(i); } | |
| 3733 | |
| 3734 HeapWord** global_finger_addr() { return &_global_finger; } | |
| 3735 | |
| 3736 CMSConcMarkingTerminator* terminator() { return &_term; } | |
| 3737 | |
|
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3738 virtual void set_for_termination(int active_workers) { |
|
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3739 terminator()->reset_for_reuse(active_workers); |
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3740 } |
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3741 |
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3742 void work(uint worker_id); |
|
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3743 bool should_yield() { |
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3744 return ConcurrentMarkSweepThread::should_yield() |
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3745 && !_collector->foregroundGCIsActive() |
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3746 && _asynch; |
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3747 } |
| 0 | 3748 |
| 3749 virtual void coordinator_yield(); // stuff done by coordinator | |
| 3750 bool result() { return _result; } | |
| 3751 | |
| 3752 void reset(HeapWord* ra) { | |
|
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3753 assert(_global_finger >= _cms_space->end(), "Postcondition of ::work(i)"); |
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3754 _restart_addr = _global_finger = ra; |
| 0 | 3755 _term.reset_for_reuse(); |
| 3756 } | |
| 3757 | |
| 3758 static bool get_work_from_overflow_stack(CMSMarkStack* ovflw_stk, | |
| 3759 OopTaskQueue* work_q); | |
| 3760 | |
| 3761 private: | |
| 3762 void do_scan_and_mark(int i, CompactibleFreeListSpace* sp); | |
| 3763 void do_work_steal(int i); | |
| 3764 void bump_global_finger(HeapWord* f); | |
| 3765 }; | |
| 3766 | |
|
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3767 bool CMSConcMarkingTerminatorTerminator::should_exit_termination() { |
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3768 assert(_task != NULL, "Error"); |
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3769 return _task->yielding(); |
|
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3770 // Note that we do not need the disjunct || _task->should_yield() above |
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3771 // because we want terminating threads to yield only if the task |
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3772 // is already in the midst of yielding, which happens only after at least one |
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3773 // thread has yielded. |
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3774 } |
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3775 |
| 0 | 3776 void CMSConcMarkingTerminator::yield() { |
|
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|
3777 if (_task->should_yield()) { |
| 0 | 3778 _task->yield(); |
| 3779 } else { | |
| 3780 ParallelTaskTerminator::yield(); | |
| 3781 } | |
| 3782 } | |
| 3783 | |
| 3784 //////////////////////////////////////////////////////////////// | |
| 3785 // Concurrent Marking Algorithm Sketch | |
| 3786 //////////////////////////////////////////////////////////////// | |
| 3787 // Until all tasks exhausted (both spaces): | |
| 3788 // -- claim next available chunk | |
| 3789 // -- bump global finger via CAS | |
| 3790 // -- find first object that starts in this chunk | |
| 3791 // and start scanning bitmap from that position | |
| 3792 // -- scan marked objects for oops | |
| 3793 // -- CAS-mark target, and if successful: | |
| 3794 // . if target oop is above global finger (volatile read) | |
| 3795 // nothing to do | |
| 3796 // . if target oop is in chunk and above local finger | |
| 3797 // then nothing to do | |
| 3798 // . else push on work-queue | |
| 3799 // -- Deal with possible overflow issues: | |
| 3800 // . local work-queue overflow causes stuff to be pushed on | |
| 3801 // global (common) overflow queue | |
| 3802 // . always first empty local work queue | |
| 3803 // . then get a batch of oops from global work queue if any | |
| 3804 // . then do work stealing | |
| 3805 // -- When all tasks claimed (both spaces) | |
| 3806 // and local work queue empty, | |
| 3807 // then in a loop do: | |
| 3808 // . check global overflow stack; steal a batch of oops and trace | |
| 3809 // . try to steal from other threads oif GOS is empty | |
| 3810 // . if neither is available, offer termination | |
| 3811 // -- Terminate and return result | |
| 3812 // | |
|
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3813 void CMSConcMarkingTask::work(uint worker_id) { |
| 0 | 3814 elapsedTimer _timer; |
| 3815 ResourceMark rm; | |
| 3816 HandleMark hm; | |
| 3817 | |
| 3818 DEBUG_ONLY(_collector->verify_overflow_empty();) | |
| 3819 | |
| 3820 // Before we begin work, our work queue should be empty | |
|
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3821 assert(work_queue(worker_id)->size() == 0, "Expected to be empty"); |
| 0 | 3822 // Scan the bitmap covering _cms_space, tracing through grey objects. |
| 3823 _timer.start(); | |
|
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3824 do_scan_and_mark(worker_id, _cms_space); |
| 0 | 3825 _timer.stop(); |
| 3826 if (PrintCMSStatistics != 0) { | |
| 3827 gclog_or_tty->print_cr("Finished cms space scanning in %dth thread: %3.3f sec", | |
|
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3828 worker_id, _timer.seconds()); |
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3829 // XXX: need xxx/xxx type of notation, two timers |
| 0 | 3830 } |
| 3831 | |
| 3832 // ... do work stealing | |
| 3833 _timer.reset(); | |
| 3834 _timer.start(); | |
|
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|
3835 do_work_steal(worker_id); |
| 0 | 3836 _timer.stop(); |
| 3837 if (PrintCMSStatistics != 0) { | |
| 3838 gclog_or_tty->print_cr("Finished work stealing in %dth thread: %3.3f sec", | |
|
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|
3839 worker_id, _timer.seconds()); |
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3840 // XXX: need xxx/xxx type of notation, two timers |
| 0 | 3841 } |
| 3842 assert(_collector->_markStack.isEmpty(), "Should have been emptied"); | |
|
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3843 assert(work_queue(worker_id)->size() == 0, "Should have been emptied"); |
| 0 | 3844 // Note that under the current task protocol, the |
| 3845 // following assertion is true even of the spaces | |
| 3846 // expanded since the completion of the concurrent | |
| 3847 // marking. XXX This will likely change under a strict | |
| 3848 // ABORT semantics. | |
|
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3849 // After perm removal the comparison was changed to |
|
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3850 // greater than or equal to from strictly greater than. |
|
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3851 // Before perm removal the highest address sweep would |
|
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3852 // have been at the end of perm gen but now is at the |
|
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|
3853 // end of the tenured gen. |
|
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|
3854 assert(_global_finger >= _cms_space->end(), |
| 0 | 3855 "All tasks have been completed"); |
| 3856 DEBUG_ONLY(_collector->verify_overflow_empty();) | |
| 3857 } | |
| 3858 | |
| 3859 void CMSConcMarkingTask::bump_global_finger(HeapWord* f) { | |
| 3860 HeapWord* read = _global_finger; | |
| 3861 HeapWord* cur = read; | |
| 3862 while (f > read) { | |
| 3863 cur = read; | |
| 3864 read = (HeapWord*) Atomic::cmpxchg_ptr(f, &_global_finger, cur); | |
| 3865 if (cur == read) { | |
| 3866 // our cas succeeded | |
| 3867 assert(_global_finger >= f, "protocol consistency"); | |
| 3868 break; | |
| 3869 } | |
| 3870 } | |
| 3871 } | |
| 3872 | |
| 3873 // This is really inefficient, and should be redone by | |
| 3874 // using (not yet available) block-read and -write interfaces to the | |
| 3875 // stack and the work_queue. XXX FIX ME !!! | |
| 3876 bool CMSConcMarkingTask::get_work_from_overflow_stack(CMSMarkStack* ovflw_stk, | |
| 3877 OopTaskQueue* work_q) { | |
| 3878 // Fast lock-free check | |
| 3879 if (ovflw_stk->length() == 0) { | |
| 3880 return false; | |
| 3881 } | |
| 3882 assert(work_q->size() == 0, "Shouldn't steal"); | |
| 3883 MutexLockerEx ml(ovflw_stk->par_lock(), | |
| 3884 Mutex::_no_safepoint_check_flag); | |
| 3885 // Grab up to 1/4 the size of the work queue | |
|
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|
3886 size_t num = MIN2((size_t)(work_q->max_elems() - work_q->size())/4, |
| 0 | 3887 (size_t)ParGCDesiredObjsFromOverflowList); |
| 3888 num = MIN2(num, ovflw_stk->length()); | |
| 3889 for (int i = (int) num; i > 0; i--) { | |
| 3890 oop cur = ovflw_stk->pop(); | |
| 3891 assert(cur != NULL, "Counted wrong?"); | |
| 3892 work_q->push(cur); | |
| 3893 } | |
| 3894 return num > 0; | |
| 3895 } | |
| 3896 | |
| 3897 void CMSConcMarkingTask::do_scan_and_mark(int i, CompactibleFreeListSpace* sp) { | |
| 3898 SequentialSubTasksDone* pst = sp->conc_par_seq_tasks(); | |
| 3899 int n_tasks = pst->n_tasks(); | |
| 3900 // We allow that there may be no tasks to do here because | |
| 3901 // we are restarting after a stack overflow. | |
|
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3902 assert(pst->valid() || n_tasks == 0, "Uninitialized use?"); |
|
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3903 uint nth_task = 0; |
| 0 | 3904 |
|
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3905 HeapWord* aligned_start = sp->bottom(); |
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3906 if (sp->used_region().contains(_restart_addr)) { |
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3907 // Align down to a card boundary for the start of 0th task |
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3908 // for this space. |
|
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3909 aligned_start = |
|
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|
3910 (HeapWord*)align_size_down((uintptr_t)_restart_addr, |
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3911 CardTableModRefBS::card_size); |
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3912 } |
|
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3913 |
| 0 | 3914 size_t chunk_size = sp->marking_task_size(); |
| 3915 while (!pst->is_task_claimed(/* reference */ nth_task)) { | |
| 3916 // Having claimed the nth task in this space, | |
| 3917 // compute the chunk that it corresponds to: | |
|
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3918 MemRegion span = MemRegion(aligned_start + nth_task*chunk_size, |
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3919 aligned_start + (nth_task+1)*chunk_size); |
| 0 | 3920 // Try and bump the global finger via a CAS; |
| 3921 // note that we need to do the global finger bump | |
| 3922 // _before_ taking the intersection below, because | |
| 3923 // the task corresponding to that region will be | |
| 3924 // deemed done even if the used_region() expands | |
| 3925 // because of allocation -- as it almost certainly will | |
| 3926 // during start-up while the threads yield in the | |
| 3927 // closure below. | |
| 3928 HeapWord* finger = span.end(); | |
| 3929 bump_global_finger(finger); // atomically | |
| 3930 // There are null tasks here corresponding to chunks | |
| 3931 // beyond the "top" address of the space. | |
| 3932 span = span.intersection(sp->used_region()); | |
| 3933 if (!span.is_empty()) { // Non-null task | |
|
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3934 HeapWord* prev_obj; |
|
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|
3935 assert(!span.contains(_restart_addr) || nth_task == 0, |
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3936 "Inconsistency"); |
|
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|
3937 if (nth_task == 0) { |
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3938 // For the 0th task, we'll not need to compute a block_start. |
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3939 if (span.contains(_restart_addr)) { |
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3940 // In the case of a restart because of stack overflow, |
|
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3941 // we might additionally skip a chunk prefix. |
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3942 prev_obj = _restart_addr; |
| 0 | 3943 } else { |
|
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3944 prev_obj = span.start(); |
|
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|
3945 } |
|
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3946 } else { |
|
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3947 // We want to skip the first object because |
|
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3948 // the protocol is to scan any object in its entirety |
|
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3949 // that _starts_ in this span; a fortiori, any |
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3950 // object starting in an earlier span is scanned |
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3951 // as part of an earlier claimed task. |
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3952 // Below we use the "careful" version of block_start |
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3953 // so we do not try to navigate uninitialized objects. |
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3954 prev_obj = sp->block_start_careful(span.start()); |
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3955 // Below we use a variant of block_size that uses the |
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3956 // Printezis bits to avoid waiting for allocated |
|
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3957 // objects to become initialized/parsable. |
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3958 while (prev_obj < span.start()) { |
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3959 size_t sz = sp->block_size_no_stall(prev_obj, _collector); |
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3960 if (sz > 0) { |
|
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3961 prev_obj += sz; |
|
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3962 } else { |
|
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3963 // In this case we may end up doing a bit of redundant |
|
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3964 // scanning, but that appears unavoidable, short of |
|
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3965 // locking the free list locks; see bug 6324141. |
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3966 break; |
|
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3967 } |
| 0 | 3968 } |
| 3969 } | |
| 3970 if (prev_obj < span.end()) { | |
| 3971 MemRegion my_span = MemRegion(prev_obj, span.end()); | |
| 3972 // Do the marking work within a non-empty span -- | |
| 3973 // the last argument to the constructor indicates whether the | |
| 3974 // iteration should be incremental with periodic yields. | |
| 3975 Par_MarkFromRootsClosure cl(this, _collector, my_span, | |
| 3976 &_collector->_markBitMap, | |
| 3977 work_queue(i), | |
| 3978 &_collector->_markStack, | |
| 3979 _asynch); | |
| 3980 _collector->_markBitMap.iterate(&cl, my_span.start(), my_span.end()); | |
| 3981 } // else nothing to do for this task | |
| 3982 } // else nothing to do for this task | |
| 3983 } | |
| 3984 // We'd be tempted to assert here that since there are no | |
| 3985 // more tasks left to claim in this space, the global_finger | |
| 3986 // must exceed space->top() and a fortiori space->end(). However, | |
| 3987 // that would not quite be correct because the bumping of | |
| 3988 // global_finger occurs strictly after the claiming of a task, | |
| 3989 // so by the time we reach here the global finger may not yet | |
| 3990 // have been bumped up by the thread that claimed the last | |
| 3991 // task. | |
| 3992 pst->all_tasks_completed(); | |
| 3993 } | |
| 3994 | |
|
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3995 class Par_ConcMarkingClosure: public CMSOopClosure { |
|
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3996 private: |
|
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3997 CMSCollector* _collector; |
|
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3998 CMSConcMarkingTask* _task; |
| 0 | 3999 MemRegion _span; |
| 4000 CMSBitMap* _bit_map; | |
| 4001 CMSMarkStack* _overflow_stack; | |
| 4002 OopTaskQueue* _work_queue; | |
|
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4003 protected: |
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4004 DO_OOP_WORK_DEFN |
| 0 | 4005 public: |
|
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4006 Par_ConcMarkingClosure(CMSCollector* collector, CMSConcMarkingTask* task, OopTaskQueue* work_queue, |
|
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4007 CMSBitMap* bit_map, CMSMarkStack* overflow_stack): |
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4008 CMSOopClosure(collector->ref_processor()), |
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4009 _collector(collector), |
|
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4010 _task(task), |
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4011 _span(collector->_span), |
| 0 | 4012 _work_queue(work_queue), |
| 4013 _bit_map(bit_map), | |
| 935 | 4014 _overflow_stack(overflow_stack) |
| 4015 { } | |
|
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4016 virtual void do_oop(oop* p); |
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4017 virtual void do_oop(narrowOop* p); |
|
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4018 |
| 0 | 4019 void trim_queue(size_t max); |
| 4020 void handle_stack_overflow(HeapWord* lost); | |
|
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4021 void do_yield_check() { |
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4022 if (_task->should_yield()) { |
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4023 _task->yield(); |
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4024 } |
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4025 } |
| 0 | 4026 }; |
| 4027 | |
|
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4028 // Grey object scanning during work stealing phase -- |
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4029 // the salient assumption here is that any references |
|
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4030 // that are in these stolen objects being scanned must |
|
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4031 // already have been initialized (else they would not have |
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4032 // been published), so we do not need to check for |
|
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4033 // uninitialized objects before pushing here. |
|
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4034 void Par_ConcMarkingClosure::do_oop(oop obj) { |
|
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4035 assert(obj->is_oop_or_null(true), "expected an oop or NULL"); |
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4036 HeapWord* addr = (HeapWord*)obj; |
| 0 | 4037 // Check if oop points into the CMS generation |
| 4038 // and is not marked | |
| 4039 if (_span.contains(addr) && !_bit_map->isMarked(addr)) { | |
| 4040 // a white object ... | |
| 4041 // If we manage to "claim" the object, by being the | |
| 4042 // first thread to mark it, then we push it on our | |
| 4043 // marking stack | |
| 4044 if (_bit_map->par_mark(addr)) { // ... now grey | |
| 4045 // push on work queue (grey set) | |
| 4046 bool simulate_overflow = false; | |
| 4047 NOT_PRODUCT( | |
| 4048 if (CMSMarkStackOverflowALot && | |
| 4049 _collector->simulate_overflow()) { | |
| 4050 // simulate a stack overflow | |
| 4051 simulate_overflow = true; | |
| 4052 } | |
| 4053 ) | |
| 4054 if (simulate_overflow || | |
|
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4055 !(_work_queue->push(obj) || _overflow_stack->par_push(obj))) { |
| 0 | 4056 // stack overflow |
| 4057 if (PrintCMSStatistics != 0) { | |
| 4058 gclog_or_tty->print_cr("CMS marking stack overflow (benign) at " | |
| 4059 SIZE_FORMAT, _overflow_stack->capacity()); | |
| 4060 } | |
| 4061 // We cannot assert that the overflow stack is full because | |
| 4062 // it may have been emptied since. | |
| 4063 assert(simulate_overflow || | |
| 4064 _work_queue->size() == _work_queue->max_elems(), | |
| 4065 "Else push should have succeeded"); | |
| 4066 handle_stack_overflow(addr); | |
| 4067 } | |
| 4068 } // Else, some other thread got there first | |
|
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4069 do_yield_check(); |
| 0 | 4070 } |
| 4071 } | |
| 4072 | |
|
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4073 void Par_ConcMarkingClosure::do_oop(oop* p) { Par_ConcMarkingClosure::do_oop_work(p); } |
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4074 void Par_ConcMarkingClosure::do_oop(narrowOop* p) { Par_ConcMarkingClosure::do_oop_work(p); } |
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4075 |
| 0 | 4076 void Par_ConcMarkingClosure::trim_queue(size_t max) { |
| 4077 while (_work_queue->size() > max) { | |
| 4078 oop new_oop; | |
| 4079 if (_work_queue->pop_local(new_oop)) { | |
| 4080 assert(new_oop->is_oop(), "Should be an oop"); | |
| 4081 assert(_bit_map->isMarked((HeapWord*)new_oop), "Grey object"); | |
| 4082 assert(_span.contains((HeapWord*)new_oop), "Not in span"); | |
| 4083 new_oop->oop_iterate(this); // do_oop() above | |
|
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|
4084 do_yield_check(); |
| 0 | 4085 } |
| 4086 } | |
| 4087 } | |
| 4088 | |
| 4089 // Upon stack overflow, we discard (part of) the stack, | |
| 4090 // remembering the least address amongst those discarded | |
| 4091 // in CMSCollector's _restart_address. | |
| 4092 void Par_ConcMarkingClosure::handle_stack_overflow(HeapWord* lost) { | |
| 4093 // We need to do this under a mutex to prevent other | |
|
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4094 // workers from interfering with the work done below. |
| 0 | 4095 MutexLockerEx ml(_overflow_stack->par_lock(), |
| 4096 Mutex::_no_safepoint_check_flag); | |
| 4097 // Remember the least grey address discarded | |
| 4098 HeapWord* ra = (HeapWord*)_overflow_stack->least_value(lost); | |
| 4099 _collector->lower_restart_addr(ra); | |
| 4100 _overflow_stack->reset(); // discard stack contents | |
| 4101 _overflow_stack->expand(); // expand the stack if possible | |
| 4102 } | |
| 4103 | |
| 4104 | |
| 4105 void CMSConcMarkingTask::do_work_steal(int i) { | |
| 4106 OopTaskQueue* work_q = work_queue(i); | |
| 4107 oop obj_to_scan; | |
| 4108 CMSBitMap* bm = &(_collector->_markBitMap); | |
| 4109 CMSMarkStack* ovflw = &(_collector->_markStack); | |
| 4110 int* seed = _collector->hash_seed(i); | |
|
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4111 Par_ConcMarkingClosure cl(_collector, this, work_q, bm, ovflw); |
| 0 | 4112 while (true) { |
| 4113 cl.trim_queue(0); | |
| 4114 assert(work_q->size() == 0, "Should have been emptied above"); | |
| 4115 if (get_work_from_overflow_stack(ovflw, work_q)) { | |
| 4116 // Can't assert below because the work obtained from the | |
| 4117 // overflow stack may already have been stolen from us. | |
| 4118 // assert(work_q->size() > 0, "Work from overflow stack"); | |
| 4119 continue; | |
| 4120 } else if (task_queues()->steal(i, seed, /* reference */ obj_to_scan)) { | |
| 4121 assert(obj_to_scan->is_oop(), "Should be an oop"); | |
| 4122 assert(bm->isMarked((HeapWord*)obj_to_scan), "Grey object"); | |
| 4123 obj_to_scan->oop_iterate(&cl); | |
|
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4124 } else if (terminator()->offer_termination(&_term_term)) { |
| 0 | 4125 assert(work_q->size() == 0, "Impossible!"); |
| 4126 break; | |
|
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4127 } else if (yielding() || should_yield()) { |
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|
4128 yield(); |
| 0 | 4129 } |
| 4130 } | |
| 4131 } | |
| 4132 | |
| 4133 // This is run by the CMS (coordinator) thread. | |
| 4134 void CMSConcMarkingTask::coordinator_yield() { | |
| 4135 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 4136 "CMS thread should hold CMS token"); | |
| 4137 // First give up the locks, then yield, then re-lock | |
| 4138 // We should probably use a constructor/destructor idiom to | |
| 4139 // do this unlock/lock or modify the MutexUnlocker class to | |
| 4140 // serve our purpose. XXX | |
| 4141 assert_lock_strong(_bit_map_lock); | |
| 4142 _bit_map_lock->unlock(); | |
| 4143 ConcurrentMarkSweepThread::desynchronize(true); | |
| 4144 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 4145 _collector->stopTimer(); | |
| 4146 if (PrintCMSStatistics != 0) { | |
| 4147 _collector->incrementYields(); | |
| 4148 } | |
| 4149 _collector->icms_wait(); | |
| 4150 | |
| 4151 // It is possible for whichever thread initiated the yield request | |
| 4152 // not to get a chance to wake up and take the bitmap lock between | |
| 4153 // this thread releasing it and reacquiring it. So, while the | |
| 4154 // should_yield() flag is on, let's sleep for a bit to give the | |
| 4155 // other thread a chance to wake up. The limit imposed on the number | |
| 4156 // of iterations is defensive, to avoid any unforseen circumstances | |
| 4157 // putting us into an infinite loop. Since it's always been this | |
| 4158 // (coordinator_yield()) method that was observed to cause the | |
| 4159 // problem, we are using a parameter (CMSCoordinatorYieldSleepCount) | |
| 4160 // which is by default non-zero. For the other seven methods that | |
| 4161 // also perform the yield operation, as are using a different | |
| 4162 // parameter (CMSYieldSleepCount) which is by default zero. This way we | |
| 4163 // can enable the sleeping for those methods too, if necessary. | |
| 4164 // See 6442774. | |
| 4165 // | |
| 4166 // We really need to reconsider the synchronization between the GC | |
| 4167 // thread and the yield-requesting threads in the future and we | |
| 4168 // should really use wait/notify, which is the recommended | |
| 4169 // way of doing this type of interaction. Additionally, we should | |
| 4170 // consolidate the eight methods that do the yield operation and they | |
| 4171 // are almost identical into one for better maintenability and | |
| 4172 // readability. See 6445193. | |
| 4173 // | |
| 4174 // Tony 2006.06.29 | |
| 4175 for (unsigned i = 0; i < CMSCoordinatorYieldSleepCount && | |
|
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4176 ConcurrentMarkSweepThread::should_yield() && |
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4177 !CMSCollector::foregroundGCIsActive(); ++i) { |
| 0 | 4178 os::sleep(Thread::current(), 1, false); |
| 4179 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 4180 } | |
| 4181 | |
| 4182 ConcurrentMarkSweepThread::synchronize(true); | |
| 4183 _bit_map_lock->lock_without_safepoint_check(); | |
| 4184 _collector->startTimer(); | |
| 4185 } | |
| 4186 | |
| 4187 bool CMSCollector::do_marking_mt(bool asynch) { | |
| 1284 | 4188 assert(ConcGCThreads > 0 && conc_workers() != NULL, "precondition"); |
|
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4189 int num_workers = AdaptiveSizePolicy::calc_active_conc_workers( |
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4190 conc_workers()->total_workers(), |
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4191 conc_workers()->active_workers(), |
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4192 Threads::number_of_non_daemon_threads()); |
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|
4193 conc_workers()->set_active_workers(num_workers); |
| 0 | 4194 |
| 4195 CompactibleFreeListSpace* cms_space = _cmsGen->cmsSpace(); | |
| 4196 | |
|
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4197 CMSConcMarkingTask tsk(this, |
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4198 cms_space, |
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4199 asynch, |
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4200 conc_workers(), |
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|
4201 task_queues()); |
| 0 | 4202 |
| 4203 // Since the actual number of workers we get may be different | |
| 4204 // from the number we requested above, do we need to do anything different | |
| 4205 // below? In particular, may be we need to subclass the SequantialSubTasksDone | |
| 4206 // class?? XXX | |
| 4207 cms_space ->initialize_sequential_subtasks_for_marking(num_workers); | |
| 4208 | |
| 4209 // Refs discovery is already non-atomic. | |
| 4210 assert(!ref_processor()->discovery_is_atomic(), "Should be non-atomic"); | |
|
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4211 assert(ref_processor()->discovery_is_mt(), "Discovery should be MT"); |
| 0 | 4212 conc_workers()->start_task(&tsk); |
| 4213 while (tsk.yielded()) { | |
| 4214 tsk.coordinator_yield(); | |
| 4215 conc_workers()->continue_task(&tsk); | |
| 4216 } | |
| 4217 // If the task was aborted, _restart_addr will be non-NULL | |
| 4218 assert(tsk.completed() || _restart_addr != NULL, "Inconsistency"); | |
| 4219 while (_restart_addr != NULL) { | |
| 4220 // XXX For now we do not make use of ABORTED state and have not | |
| 4221 // yet implemented the right abort semantics (even in the original | |
| 4222 // single-threaded CMS case). That needs some more investigation | |
| 4223 // and is deferred for now; see CR# TBF. 07252005YSR. XXX | |
| 4224 assert(!CMSAbortSemantics || tsk.aborted(), "Inconsistency"); | |
| 4225 // If _restart_addr is non-NULL, a marking stack overflow | |
| 605 | 4226 // occurred; we need to do a fresh marking iteration from the |
| 0 | 4227 // indicated restart address. |
| 4228 if (_foregroundGCIsActive && asynch) { | |
| 4229 // We may be running into repeated stack overflows, having | |
| 4230 // reached the limit of the stack size, while making very | |
| 4231 // slow forward progress. It may be best to bail out and | |
| 4232 // let the foreground collector do its job. | |
| 4233 // Clear _restart_addr, so that foreground GC | |
| 4234 // works from scratch. This avoids the headache of | |
| 4235 // a "rescan" which would otherwise be needed because | |
| 4236 // of the dirty mod union table & card table. | |
| 4237 _restart_addr = NULL; | |
| 4238 return false; | |
| 4239 } | |
| 4240 // Adjust the task to restart from _restart_addr | |
| 4241 tsk.reset(_restart_addr); | |
| 4242 cms_space ->initialize_sequential_subtasks_for_marking(num_workers, | |
| 4243 _restart_addr); | |
| 4244 _restart_addr = NULL; | |
| 4245 // Get the workers going again | |
| 4246 conc_workers()->start_task(&tsk); | |
| 4247 while (tsk.yielded()) { | |
| 4248 tsk.coordinator_yield(); | |
| 4249 conc_workers()->continue_task(&tsk); | |
| 4250 } | |
| 4251 } | |
| 4252 assert(tsk.completed(), "Inconsistency"); | |
| 4253 assert(tsk.result() == true, "Inconsistency"); | |
| 4254 return true; | |
| 4255 } | |
| 4256 | |
| 4257 bool CMSCollector::do_marking_st(bool asynch) { | |
| 4258 ResourceMark rm; | |
| 4259 HandleMark hm; | |
| 4260 | |
|
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4261 // Temporarily make refs discovery single threaded (non-MT) |
|
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4262 ReferenceProcessorMTDiscoveryMutator rp_mut_discovery(ref_processor(), false); |
| 0 | 4263 MarkFromRootsClosure markFromRootsClosure(this, _span, &_markBitMap, |
|
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4264 &_markStack, CMSYield && asynch); |
| 0 | 4265 // the last argument to iterate indicates whether the iteration |
| 4266 // should be incremental with periodic yields. | |
| 4267 _markBitMap.iterate(&markFromRootsClosure); | |
| 4268 // If _restart_addr is non-NULL, a marking stack overflow | |
| 605 | 4269 // occurred; we need to do a fresh iteration from the |
| 0 | 4270 // indicated restart address. |
| 4271 while (_restart_addr != NULL) { | |
| 4272 if (_foregroundGCIsActive && asynch) { | |
| 4273 // We may be running into repeated stack overflows, having | |
| 4274 // reached the limit of the stack size, while making very | |
| 4275 // slow forward progress. It may be best to bail out and | |
| 4276 // let the foreground collector do its job. | |
| 4277 // Clear _restart_addr, so that foreground GC | |
| 4278 // works from scratch. This avoids the headache of | |
| 4279 // a "rescan" which would otherwise be needed because | |
| 4280 // of the dirty mod union table & card table. | |
| 4281 _restart_addr = NULL; | |
| 4282 return false; // indicating failure to complete marking | |
| 4283 } | |
| 4284 // Deal with stack overflow: | |
| 4285 // we restart marking from _restart_addr | |
| 4286 HeapWord* ra = _restart_addr; | |
| 4287 markFromRootsClosure.reset(ra); | |
| 4288 _restart_addr = NULL; | |
| 4289 _markBitMap.iterate(&markFromRootsClosure, ra, _span.end()); | |
| 4290 } | |
| 4291 return true; | |
| 4292 } | |
| 4293 | |
| 4294 void CMSCollector::preclean() { | |
| 4295 check_correct_thread_executing(); | |
| 4296 assert(Thread::current()->is_ConcurrentGC_thread(), "Wrong thread"); | |
| 4297 verify_work_stacks_empty(); | |
| 4298 verify_overflow_empty(); | |
| 4299 _abort_preclean = false; | |
| 4300 if (CMSPrecleaningEnabled) { | |
| 4301 _eden_chunk_index = 0; | |
| 4302 size_t used = get_eden_used(); | |
| 4303 size_t capacity = get_eden_capacity(); | |
| 4304 // Don't start sampling unless we will get sufficiently | |
| 4305 // many samples. | |
| 4306 if (used < (capacity/(CMSScheduleRemarkSamplingRatio * 100) | |
| 4307 * CMSScheduleRemarkEdenPenetration)) { | |
| 4308 _start_sampling = true; | |
| 4309 } else { | |
| 4310 _start_sampling = false; | |
| 4311 } | |
| 4312 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
| 4313 CMSPhaseAccounting pa(this, "preclean", !PrintGCDetails); | |
| 4314 preclean_work(CMSPrecleanRefLists1, CMSPrecleanSurvivors1); | |
| 4315 } | |
| 4316 CMSTokenSync x(true); // is cms thread | |
| 4317 if (CMSPrecleaningEnabled) { | |
| 4318 sample_eden(); | |
| 4319 _collectorState = AbortablePreclean; | |
| 4320 } else { | |
| 4321 _collectorState = FinalMarking; | |
| 4322 } | |
| 4323 verify_work_stacks_empty(); | |
| 4324 verify_overflow_empty(); | |
| 4325 } | |
| 4326 | |
| 4327 // Try and schedule the remark such that young gen | |
| 4328 // occupancy is CMSScheduleRemarkEdenPenetration %. | |
| 4329 void CMSCollector::abortable_preclean() { | |
| 4330 check_correct_thread_executing(); | |
| 4331 assert(CMSPrecleaningEnabled, "Inconsistent control state"); | |
| 4332 assert(_collectorState == AbortablePreclean, "Inconsistent control state"); | |
| 4333 | |
| 4334 // If Eden's current occupancy is below this threshold, | |
| 4335 // immediately schedule the remark; else preclean | |
| 4336 // past the next scavenge in an effort to | |
| 4337 // schedule the pause as described avove. By choosing | |
| 4338 // CMSScheduleRemarkEdenSizeThreshold >= max eden size | |
| 4339 // we will never do an actual abortable preclean cycle. | |
| 4340 if (get_eden_used() > CMSScheduleRemarkEdenSizeThreshold) { | |
| 4341 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
| 4342 CMSPhaseAccounting pa(this, "abortable-preclean", !PrintGCDetails); | |
| 4343 // We need more smarts in the abortable preclean | |
| 4344 // loop below to deal with cases where allocation | |
| 4345 // in young gen is very very slow, and our precleaning | |
| 4346 // is running a losing race against a horde of | |
| 4347 // mutators intent on flooding us with CMS updates | |
| 4348 // (dirty cards). | |
| 4349 // One, admittedly dumb, strategy is to give up | |
| 4350 // after a certain number of abortable precleaning loops | |
| 4351 // or after a certain maximum time. We want to make | |
| 4352 // this smarter in the next iteration. | |
| 4353 // XXX FIX ME!!! YSR | |
| 4354 size_t loops = 0, workdone = 0, cumworkdone = 0, waited = 0; | |
| 4355 while (!(should_abort_preclean() || | |
| 4356 ConcurrentMarkSweepThread::should_terminate())) { | |
| 4357 workdone = preclean_work(CMSPrecleanRefLists2, CMSPrecleanSurvivors2); | |
| 4358 cumworkdone += workdone; | |
| 4359 loops++; | |
| 4360 // Voluntarily terminate abortable preclean phase if we have | |
| 4361 // been at it for too long. | |
| 4362 if ((CMSMaxAbortablePrecleanLoops != 0) && | |
| 4363 loops >= CMSMaxAbortablePrecleanLoops) { | |
| 4364 if (PrintGCDetails) { | |
| 4365 gclog_or_tty->print(" CMS: abort preclean due to loops "); | |
| 4366 } | |
| 4367 break; | |
| 4368 } | |
| 4369 if (pa.wallclock_millis() > CMSMaxAbortablePrecleanTime) { | |
| 4370 if (PrintGCDetails) { | |
| 4371 gclog_or_tty->print(" CMS: abort preclean due to time "); | |
| 4372 } | |
| 4373 break; | |
| 4374 } | |
| 4375 // If we are doing little work each iteration, we should | |
| 4376 // take a short break. | |
| 4377 if (workdone < CMSAbortablePrecleanMinWorkPerIteration) { | |
| 4378 // Sleep for some time, waiting for work to accumulate | |
| 4379 stopTimer(); | |
| 4380 cmsThread()->wait_on_cms_lock(CMSAbortablePrecleanWaitMillis); | |
| 4381 startTimer(); | |
| 4382 waited++; | |
| 4383 } | |
| 4384 } | |
| 4385 if (PrintCMSStatistics > 0) { | |
| 4386 gclog_or_tty->print(" [%d iterations, %d waits, %d cards)] ", | |
| 4387 loops, waited, cumworkdone); | |
| 4388 } | |
| 4389 } | |
| 4390 CMSTokenSync x(true); // is cms thread | |
| 4391 if (_collectorState != Idling) { | |
| 4392 assert(_collectorState == AbortablePreclean, | |
| 4393 "Spontaneous state transition?"); | |
| 4394 _collectorState = FinalMarking; | |
| 4395 } // Else, a foreground collection completed this CMS cycle. | |
| 4396 return; | |
| 4397 } | |
| 4398 | |
| 4399 // Respond to an Eden sampling opportunity | |
| 4400 void CMSCollector::sample_eden() { | |
| 4401 // Make sure a young gc cannot sneak in between our | |
| 4402 // reading and recording of a sample. | |
| 4403 assert(Thread::current()->is_ConcurrentGC_thread(), | |
| 4404 "Only the cms thread may collect Eden samples"); | |
| 4405 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 4406 "Should collect samples while holding CMS token"); | |
| 4407 if (!_start_sampling) { | |
| 4408 return; | |
| 4409 } | |
| 4410 if (_eden_chunk_array) { | |
| 4411 if (_eden_chunk_index < _eden_chunk_capacity) { | |
| 4412 _eden_chunk_array[_eden_chunk_index] = *_top_addr; // take sample | |
| 4413 assert(_eden_chunk_array[_eden_chunk_index] <= *_end_addr, | |
| 4414 "Unexpected state of Eden"); | |
| 4415 // We'd like to check that what we just sampled is an oop-start address; | |
| 4416 // however, we cannot do that here since the object may not yet have been | |
| 4417 // initialized. So we'll instead do the check when we _use_ this sample | |
| 4418 // later. | |
| 4419 if (_eden_chunk_index == 0 || | |
| 4420 (pointer_delta(_eden_chunk_array[_eden_chunk_index], | |
| 4421 _eden_chunk_array[_eden_chunk_index-1]) | |
| 4422 >= CMSSamplingGrain)) { | |
| 4423 _eden_chunk_index++; // commit sample | |
| 4424 } | |
| 4425 } | |
| 4426 } | |
| 4427 if ((_collectorState == AbortablePreclean) && !_abort_preclean) { | |
| 4428 size_t used = get_eden_used(); | |
| 4429 size_t capacity = get_eden_capacity(); | |
| 4430 assert(used <= capacity, "Unexpected state of Eden"); | |
| 4431 if (used > (capacity/100 * CMSScheduleRemarkEdenPenetration)) { | |
| 4432 _abort_preclean = true; | |
| 4433 } | |
| 4434 } | |
| 4435 } | |
| 4436 | |
| 4437 | |
| 4438 size_t CMSCollector::preclean_work(bool clean_refs, bool clean_survivor) { | |
| 4439 assert(_collectorState == Precleaning || | |
| 4440 _collectorState == AbortablePreclean, "incorrect state"); | |
| 4441 ResourceMark rm; | |
| 4442 HandleMark hm; | |
|
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4443 |
|
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4444 // Precleaning is currently not MT but the reference processor |
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4445 // may be set for MT. Disable it temporarily here. |
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4446 ReferenceProcessor* rp = ref_processor(); |
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4447 ReferenceProcessorMTDiscoveryMutator rp_mut_discovery(rp, false); |
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4448 |
| 0 | 4449 // Do one pass of scrubbing the discovered reference lists |
| 4450 // to remove any reference objects with strongly-reachable | |
| 4451 // referents. | |
| 4452 if (clean_refs) { | |
| 4453 CMSPrecleanRefsYieldClosure yield_cl(this); | |
| 4454 assert(rp->span().equals(_span), "Spans should be equal"); | |
| 4455 CMSKeepAliveClosure keep_alive(this, _span, &_markBitMap, | |
|
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4456 &_markStack, true /* preclean */); |
| 0 | 4457 CMSDrainMarkingStackClosure complete_trace(this, |
|
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4458 _span, &_markBitMap, &_markStack, |
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|
4459 &keep_alive, true /* preclean */); |
| 0 | 4460 |
| 4461 // We don't want this step to interfere with a young | |
| 4462 // collection because we don't want to take CPU | |
| 4463 // or memory bandwidth away from the young GC threads | |
| 4464 // (which may be as many as there are CPUs). | |
| 4465 // Note that we don't need to protect ourselves from | |
| 4466 // interference with mutators because they can't | |
| 4467 // manipulate the discovered reference lists nor affect | |
| 4468 // the computed reachability of the referents, the | |
| 4469 // only properties manipulated by the precleaning | |
| 4470 // of these reference lists. | |
| 4471 stopTimer(); | |
| 4472 CMSTokenSyncWithLocks x(true /* is cms thread */, | |
| 4473 bitMapLock()); | |
| 4474 startTimer(); | |
| 4475 sample_eden(); | |
| 935 | 4476 |
| 0 | 4477 // The following will yield to allow foreground |
| 4478 // collection to proceed promptly. XXX YSR: | |
| 4479 // The code in this method may need further | |
| 4480 // tweaking for better performance and some restructuring | |
| 4481 // for cleaner interfaces. | |
| 4482 rp->preclean_discovered_references( | |
|
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4483 rp->is_alive_non_header(), &keep_alive, &complete_trace, &yield_cl); |
| 0 | 4484 } |
| 4485 | |
| 4486 if (clean_survivor) { // preclean the active survivor space(s) | |
| 4487 assert(_young_gen->kind() == Generation::DefNew || | |
| 4488 _young_gen->kind() == Generation::ParNew || | |
| 4489 _young_gen->kind() == Generation::ASParNew, | |
| 4490 "incorrect type for cast"); | |
| 4491 DefNewGeneration* dng = (DefNewGeneration*)_young_gen; | |
| 4492 PushAndMarkClosure pam_cl(this, _span, ref_processor(), | |
| 4493 &_markBitMap, &_modUnionTable, | |
|
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4494 &_markStack, true /* precleaning phase */); |
| 0 | 4495 stopTimer(); |
| 4496 CMSTokenSyncWithLocks ts(true /* is cms thread */, | |
| 4497 bitMapLock()); | |
| 4498 startTimer(); | |
| 4499 unsigned int before_count = | |
| 4500 GenCollectedHeap::heap()->total_collections(); | |
| 4501 SurvivorSpacePrecleanClosure | |
| 4502 sss_cl(this, _span, &_markBitMap, &_markStack, | |
| 4503 &pam_cl, before_count, CMSYield); | |
| 4504 dng->from()->object_iterate_careful(&sss_cl); | |
| 4505 dng->to()->object_iterate_careful(&sss_cl); | |
| 4506 } | |
| 4507 MarkRefsIntoAndScanClosure | |
| 4508 mrias_cl(_span, ref_processor(), &_markBitMap, &_modUnionTable, | |
|
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4509 &_markStack, this, CMSYield, |
| 0 | 4510 true /* precleaning phase */); |
| 4511 // CAUTION: The following closure has persistent state that may need to | |
| 4512 // be reset upon a decrease in the sequence of addresses it | |
| 4513 // processes. | |
| 4514 ScanMarkedObjectsAgainCarefullyClosure | |
| 4515 smoac_cl(this, _span, | |
|
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4516 &_markBitMap, &_markStack, &mrias_cl, CMSYield); |
| 0 | 4517 |
| 4518 // Preclean dirty cards in ModUnionTable and CardTable using | |
| 4519 // appropriate convergence criterion; | |
| 4520 // repeat CMSPrecleanIter times unless we find that | |
| 4521 // we are losing. | |
| 4522 assert(CMSPrecleanIter < 10, "CMSPrecleanIter is too large"); | |
| 4523 assert(CMSPrecleanNumerator < CMSPrecleanDenominator, | |
| 4524 "Bad convergence multiplier"); | |
| 4525 assert(CMSPrecleanThreshold >= 100, | |
| 4526 "Unreasonably low CMSPrecleanThreshold"); | |
| 4527 | |
| 4528 size_t numIter, cumNumCards, lastNumCards, curNumCards; | |
| 4529 for (numIter = 0, cumNumCards = lastNumCards = curNumCards = 0; | |
| 4530 numIter < CMSPrecleanIter; | |
| 4531 numIter++, lastNumCards = curNumCards, cumNumCards += curNumCards) { | |
| 4532 curNumCards = preclean_mod_union_table(_cmsGen, &smoac_cl); | |
| 4533 if (Verbose && PrintGCDetails) { | |
| 4534 gclog_or_tty->print(" (modUnionTable: %d cards)", curNumCards); | |
| 4535 } | |
| 4536 // Either there are very few dirty cards, so re-mark | |
| 4537 // pause will be small anyway, or our pre-cleaning isn't | |
| 4538 // that much faster than the rate at which cards are being | |
| 4539 // dirtied, so we might as well stop and re-mark since | |
| 4540 // precleaning won't improve our re-mark time by much. | |
| 4541 if (curNumCards <= CMSPrecleanThreshold || | |
| 4542 (numIter > 0 && | |
| 4543 (curNumCards * CMSPrecleanDenominator > | |
| 4544 lastNumCards * CMSPrecleanNumerator))) { | |
| 4545 numIter++; | |
| 4546 cumNumCards += curNumCards; | |
| 4547 break; | |
| 4548 } | |
| 4549 } | |
|
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4550 |
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4551 preclean_klasses(&mrias_cl, _cmsGen->freelistLock()); |
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|
4552 |
| 0 | 4553 curNumCards = preclean_card_table(_cmsGen, &smoac_cl); |
| 4554 cumNumCards += curNumCards; | |
| 4555 if (PrintGCDetails && PrintCMSStatistics != 0) { | |
| 4556 gclog_or_tty->print_cr(" (cardTable: %d cards, re-scanned %d cards, %d iterations)", | |
| 4557 curNumCards, cumNumCards, numIter); | |
| 4558 } | |
| 4559 return cumNumCards; // as a measure of useful work done | |
| 4560 } | |
| 4561 | |
| 4562 // PRECLEANING NOTES: | |
| 4563 // Precleaning involves: | |
| 4564 // . reading the bits of the modUnionTable and clearing the set bits. | |
| 4565 // . For the cards corresponding to the set bits, we scan the | |
| 4566 // objects on those cards. This means we need the free_list_lock | |
| 4567 // so that we can safely iterate over the CMS space when scanning | |
| 4568 // for oops. | |
| 4569 // . When we scan the objects, we'll be both reading and setting | |
| 4570 // marks in the marking bit map, so we'll need the marking bit map. | |
| 4571 // . For protecting _collector_state transitions, we take the CGC_lock. | |
| 4572 // Note that any races in the reading of of card table entries by the | |
| 4573 // CMS thread on the one hand and the clearing of those entries by the | |
| 4574 // VM thread or the setting of those entries by the mutator threads on the | |
| 4575 // other are quite benign. However, for efficiency it makes sense to keep | |
| 4576 // the VM thread from racing with the CMS thread while the latter is | |
| 4577 // dirty card info to the modUnionTable. We therefore also use the | |
| 4578 // CGC_lock to protect the reading of the card table and the mod union | |
| 4579 // table by the CM thread. | |
| 4580 // . We run concurrently with mutator updates, so scanning | |
| 4581 // needs to be done carefully -- we should not try to scan | |
| 4582 // potentially uninitialized objects. | |
| 4583 // | |
| 4584 // Locking strategy: While holding the CGC_lock, we scan over and | |
| 4585 // reset a maximal dirty range of the mod union / card tables, then lock | |
| 4586 // the free_list_lock and bitmap lock to do a full marking, then | |
| 4587 // release these locks; and repeat the cycle. This allows for a | |
| 4588 // certain amount of fairness in the sharing of these locks between | |
| 4589 // the CMS collector on the one hand, and the VM thread and the | |
| 4590 // mutators on the other. | |
| 4591 | |
| 4592 // NOTE: preclean_mod_union_table() and preclean_card_table() | |
| 4593 // further below are largely identical; if you need to modify | |
| 4594 // one of these methods, please check the other method too. | |
| 4595 | |
| 4596 size_t CMSCollector::preclean_mod_union_table( | |
| 4597 ConcurrentMarkSweepGeneration* gen, | |
| 4598 ScanMarkedObjectsAgainCarefullyClosure* cl) { | |
| 4599 verify_work_stacks_empty(); | |
| 4600 verify_overflow_empty(); | |
| 4601 | |
| 4602 // strategy: starting with the first card, accumulate contiguous | |
| 4603 // ranges of dirty cards; clear these cards, then scan the region | |
| 4604 // covered by these cards. | |
| 4605 | |
| 4606 // Since all of the MUT is committed ahead, we can just use | |
| 4607 // that, in case the generations expand while we are precleaning. | |
| 4608 // It might also be fine to just use the committed part of the | |
| 4609 // generation, but we might potentially miss cards when the | |
| 4610 // generation is rapidly expanding while we are in the midst | |
| 4611 // of precleaning. | |
| 4612 HeapWord* startAddr = gen->reserved().start(); | |
| 4613 HeapWord* endAddr = gen->reserved().end(); | |
| 4614 | |
| 4615 cl->setFreelistLock(gen->freelistLock()); // needed for yielding | |
| 4616 | |
| 4617 size_t numDirtyCards, cumNumDirtyCards; | |
| 4618 HeapWord *nextAddr, *lastAddr; | |
| 4619 for (cumNumDirtyCards = numDirtyCards = 0, | |
| 4620 nextAddr = lastAddr = startAddr; | |
| 4621 nextAddr < endAddr; | |
| 4622 nextAddr = lastAddr, cumNumDirtyCards += numDirtyCards) { | |
| 4623 | |
| 4624 ResourceMark rm; | |
| 4625 HandleMark hm; | |
| 4626 | |
| 4627 MemRegion dirtyRegion; | |
| 4628 { | |
| 4629 stopTimer(); | |
| 935 | 4630 // Potential yield point |
| 0 | 4631 CMSTokenSync ts(true); |
| 4632 startTimer(); | |
| 4633 sample_eden(); | |
| 4634 // Get dirty region starting at nextOffset (inclusive), | |
| 4635 // simultaneously clearing it. | |
| 4636 dirtyRegion = | |
| 4637 _modUnionTable.getAndClearMarkedRegion(nextAddr, endAddr); | |
| 4638 assert(dirtyRegion.start() >= nextAddr, | |
| 4639 "returned region inconsistent?"); | |
| 4640 } | |
| 4641 // Remember where the next search should begin. | |
| 4642 // The returned region (if non-empty) is a right open interval, | |
| 4643 // so lastOffset is obtained from the right end of that | |
| 4644 // interval. | |
| 4645 lastAddr = dirtyRegion.end(); | |
| 4646 // Should do something more transparent and less hacky XXX | |
| 4647 numDirtyCards = | |
| 4648 _modUnionTable.heapWordDiffToOffsetDiff(dirtyRegion.word_size()); | |
| 4649 | |
| 4650 // We'll scan the cards in the dirty region (with periodic | |
| 4651 // yields for foreground GC as needed). | |
| 4652 if (!dirtyRegion.is_empty()) { | |
| 4653 assert(numDirtyCards > 0, "consistency check"); | |
| 4654 HeapWord* stop_point = NULL; | |
|
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4655 stopTimer(); |
| 935 | 4656 // Potential yield point |
|
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|
4657 CMSTokenSyncWithLocks ts(true, gen->freelistLock(), |
|
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|
4658 bitMapLock()); |
|
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|
4659 startTimer(); |
| 0 | 4660 { |
| 4661 verify_work_stacks_empty(); | |
| 4662 verify_overflow_empty(); | |
| 4663 sample_eden(); | |
| 4664 stop_point = | |
| 4665 gen->cmsSpace()->object_iterate_careful_m(dirtyRegion, cl); | |
| 4666 } | |
| 4667 if (stop_point != NULL) { | |
| 4668 // The careful iteration stopped early either because it found an | |
| 4669 // uninitialized object, or because we were in the midst of an | |
| 4670 // "abortable preclean", which should now be aborted. Redirty | |
| 4671 // the bits corresponding to the partially-scanned or unscanned | |
| 4672 // cards. We'll either restart at the next block boundary or | |
| 4673 // abort the preclean. | |
|
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4674 assert((_collectorState == AbortablePreclean && should_abort_preclean()), |
|
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|
4675 "Should only be AbortablePreclean."); |
| 0 | 4676 _modUnionTable.mark_range(MemRegion(stop_point, dirtyRegion.end())); |
| 4677 if (should_abort_preclean()) { | |
| 4678 break; // out of preclean loop | |
| 4679 } else { | |
| 4680 // Compute the next address at which preclean should pick up; | |
| 4681 // might need bitMapLock in order to read P-bits. | |
| 4682 lastAddr = next_card_start_after_block(stop_point); | |
| 4683 } | |
| 4684 } | |
| 4685 } else { | |
| 4686 assert(lastAddr == endAddr, "consistency check"); | |
| 4687 assert(numDirtyCards == 0, "consistency check"); | |
| 4688 break; | |
| 4689 } | |
| 4690 } | |
| 4691 verify_work_stacks_empty(); | |
| 4692 verify_overflow_empty(); | |
| 4693 return cumNumDirtyCards; | |
| 4694 } | |
| 4695 | |
| 4696 // NOTE: preclean_mod_union_table() above and preclean_card_table() | |
| 4697 // below are largely identical; if you need to modify | |
| 4698 // one of these methods, please check the other method too. | |
| 4699 | |
| 4700 size_t CMSCollector::preclean_card_table(ConcurrentMarkSweepGeneration* gen, | |
| 4701 ScanMarkedObjectsAgainCarefullyClosure* cl) { | |
| 4702 // strategy: it's similar to precleamModUnionTable above, in that | |
| 4703 // we accumulate contiguous ranges of dirty cards, mark these cards | |
| 4704 // precleaned, then scan the region covered by these cards. | |
| 4705 HeapWord* endAddr = (HeapWord*)(gen->_virtual_space.high()); | |
| 4706 HeapWord* startAddr = (HeapWord*)(gen->_virtual_space.low()); | |
| 4707 | |
| 4708 cl->setFreelistLock(gen->freelistLock()); // needed for yielding | |
| 4709 | |
| 4710 size_t numDirtyCards, cumNumDirtyCards; | |
| 4711 HeapWord *lastAddr, *nextAddr; | |
| 4712 | |
| 4713 for (cumNumDirtyCards = numDirtyCards = 0, | |
| 4714 nextAddr = lastAddr = startAddr; | |
| 4715 nextAddr < endAddr; | |
| 4716 nextAddr = lastAddr, cumNumDirtyCards += numDirtyCards) { | |
| 4717 | |
| 4718 ResourceMark rm; | |
| 4719 HandleMark hm; | |
| 4720 | |
| 4721 MemRegion dirtyRegion; | |
| 4722 { | |
| 4723 // See comments in "Precleaning notes" above on why we | |
| 4724 // do this locking. XXX Could the locking overheads be | |
| 4725 // too high when dirty cards are sparse? [I don't think so.] | |
| 4726 stopTimer(); | |
| 4727 CMSTokenSync x(true); // is cms thread | |
| 4728 startTimer(); | |
| 4729 sample_eden(); | |
| 4730 // Get and clear dirty region from card table | |
|
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4731 dirtyRegion = _ct->ct_bs()->dirty_card_range_after_reset( |
|
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|
4732 MemRegion(nextAddr, endAddr), |
|
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|
4733 true, |
|
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|
4734 CardTableModRefBS::precleaned_card_val()); |
|
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|
4735 |
| 0 | 4736 assert(dirtyRegion.start() >= nextAddr, |
| 4737 "returned region inconsistent?"); | |
| 4738 } | |
| 4739 lastAddr = dirtyRegion.end(); | |
| 4740 numDirtyCards = | |
| 4741 dirtyRegion.word_size()/CardTableModRefBS::card_size_in_words; | |
| 4742 | |
| 4743 if (!dirtyRegion.is_empty()) { | |
| 4744 stopTimer(); | |
| 4745 CMSTokenSyncWithLocks ts(true, gen->freelistLock(), bitMapLock()); | |
| 4746 startTimer(); | |
| 4747 sample_eden(); | |
| 4748 verify_work_stacks_empty(); | |
| 4749 verify_overflow_empty(); | |
| 4750 HeapWord* stop_point = | |
| 4751 gen->cmsSpace()->object_iterate_careful_m(dirtyRegion, cl); | |
| 4752 if (stop_point != NULL) { | |
|
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4753 assert((_collectorState == AbortablePreclean && should_abort_preclean()), |
|
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|
4754 "Should only be AbortablePreclean."); |
| 0 | 4755 _ct->ct_bs()->invalidate(MemRegion(stop_point, dirtyRegion.end())); |
| 4756 if (should_abort_preclean()) { | |
| 4757 break; // out of preclean loop | |
| 4758 } else { | |
| 4759 // Compute the next address at which preclean should pick up. | |
| 4760 lastAddr = next_card_start_after_block(stop_point); | |
| 4761 } | |
| 4762 } | |
| 4763 } else { | |
| 4764 break; | |
| 4765 } | |
| 4766 } | |
| 4767 verify_work_stacks_empty(); | |
| 4768 verify_overflow_empty(); | |
| 4769 return cumNumDirtyCards; | |
| 4770 } | |
| 4771 | |
|
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4772 class PrecleanKlassClosure : public KlassClosure { |
|
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4773 CMKlassClosure _cm_klass_closure; |
|
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4774 public: |
|
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4775 PrecleanKlassClosure(OopClosure* oop_closure) : _cm_klass_closure(oop_closure) {} |
|
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4776 void do_klass(Klass* k) { |
|
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4777 if (k->has_accumulated_modified_oops()) { |
|
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4778 k->clear_accumulated_modified_oops(); |
|
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4779 |
|
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4780 _cm_klass_closure.do_klass(k); |
|
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|
4781 } |
|
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|
4782 } |
|
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|
4783 }; |
|
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|
4784 |
|
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4785 // The freelist lock is needed to prevent asserts, is it really needed? |
|
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|
4786 void CMSCollector::preclean_klasses(MarkRefsIntoAndScanClosure* cl, Mutex* freelistLock) { |
|
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4787 |
|
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|
4788 cl->set_freelistLock(freelistLock); |
|
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4789 |
|
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|
4790 CMSTokenSyncWithLocks ts(true, freelistLock, bitMapLock()); |
|
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4791 |
|
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|
4792 // SSS: Add equivalent to ScanMarkedObjectsAgainCarefullyClosure::do_yield_check and should_abort_preclean? |
|
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|
4793 // SSS: We should probably check if precleaning should be aborted, at suitable intervals? |
|
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4794 PrecleanKlassClosure preclean_klass_closure(cl); |
|
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4795 ClassLoaderDataGraph::classes_do(&preclean_klass_closure); |
|
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4796 |
|
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4797 verify_work_stacks_empty(); |
|
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4798 verify_overflow_empty(); |
|
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|
4799 } |
|
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|
4800 |
| 0 | 4801 void CMSCollector::checkpointRootsFinal(bool asynch, |
| 4802 bool clear_all_soft_refs, bool init_mark_was_synchronous) { | |
| 4803 assert(_collectorState == FinalMarking, "incorrect state transition?"); | |
| 4804 check_correct_thread_executing(); | |
| 4805 // world is stopped at this checkpoint | |
| 4806 assert(SafepointSynchronize::is_at_safepoint(), | |
| 4807 "world should be stopped"); | |
|
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|
4808 TraceCMSMemoryManagerStats tms(_collectorState,GenCollectedHeap::heap()->gc_cause()); |
|
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|
4809 |
| 0 | 4810 verify_work_stacks_empty(); |
| 4811 verify_overflow_empty(); | |
| 4812 | |
| 4813 SpecializationStats::clear(); | |
| 4814 if (PrintGCDetails) { | |
| 4815 gclog_or_tty->print("[YG occupancy: "SIZE_FORMAT" K ("SIZE_FORMAT" K)]", | |
| 4816 _young_gen->used() / K, | |
| 4817 _young_gen->capacity() / K); | |
| 4818 } | |
| 4819 if (asynch) { | |
| 4820 if (CMSScavengeBeforeRemark) { | |
| 4821 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 4822 // Temporarily set flag to false, GCH->do_collection will | |
| 4823 // expect it to be false and set to true | |
| 4824 FlagSetting fl(gch->_is_gc_active, false); | |
| 4825 NOT_PRODUCT(TraceTime t("Scavenge-Before-Remark", | |
| 4826 PrintGCDetails && Verbose, true, gclog_or_tty);) | |
| 4827 int level = _cmsGen->level() - 1; | |
| 4828 if (level >= 0) { | |
| 4829 gch->do_collection(true, // full (i.e. force, see below) | |
| 4830 false, // !clear_all_soft_refs | |
| 4831 0, // size | |
| 4832 false, // is_tlab | |
| 4833 level // max_level | |
| 4834 ); | |
| 4835 } | |
| 4836 } | |
| 4837 FreelistLocker x(this); | |
| 4838 MutexLockerEx y(bitMapLock(), | |
| 4839 Mutex::_no_safepoint_check_flag); | |
| 4840 assert(!init_mark_was_synchronous, "but that's impossible!"); | |
| 4841 checkpointRootsFinalWork(asynch, clear_all_soft_refs, false); | |
| 4842 } else { | |
| 4843 // already have all the locks | |
| 4844 checkpointRootsFinalWork(asynch, clear_all_soft_refs, | |
| 4845 init_mark_was_synchronous); | |
| 4846 } | |
| 4847 verify_work_stacks_empty(); | |
| 4848 verify_overflow_empty(); | |
| 4849 SpecializationStats::print(); | |
| 4850 } | |
| 4851 | |
| 4852 void CMSCollector::checkpointRootsFinalWork(bool asynch, | |
| 4853 bool clear_all_soft_refs, bool init_mark_was_synchronous) { | |
| 4854 | |
| 4855 NOT_PRODUCT(TraceTime tr("checkpointRootsFinalWork", PrintGCDetails, false, gclog_or_tty);) | |
| 4856 | |
| 4857 assert(haveFreelistLocks(), "must have free list locks"); | |
| 4858 assert_lock_strong(bitMapLock()); | |
| 4859 | |
| 4860 if (UseAdaptiveSizePolicy) { | |
| 4861 size_policy()->checkpoint_roots_final_begin(); | |
| 4862 } | |
| 4863 | |
| 4864 ResourceMark rm; | |
| 4865 HandleMark hm; | |
| 4866 | |
| 4867 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 4868 | |
|
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|
4869 if (should_unload_classes()) { |
| 0 | 4870 CodeCache::gc_prologue(); |
| 4871 } | |
| 4872 assert(haveFreelistLocks(), "must have free list locks"); | |
| 4873 assert_lock_strong(bitMapLock()); | |
| 4874 | |
| 4875 if (!init_mark_was_synchronous) { | |
| 4876 // We might assume that we need not fill TLAB's when | |
| 4877 // CMSScavengeBeforeRemark is set, because we may have just done | |
| 4878 // a scavenge which would have filled all TLAB's -- and besides | |
| 4879 // Eden would be empty. This however may not always be the case -- | |
| 4880 // for instance although we asked for a scavenge, it may not have | |
| 4881 // happened because of a JNI critical section. We probably need | |
| 4882 // a policy for deciding whether we can in that case wait until | |
| 4883 // the critical section releases and then do the remark following | |
| 4884 // the scavenge, and skip it here. In the absence of that policy, | |
| 4885 // or of an indication of whether the scavenge did indeed occur, | |
| 4886 // we cannot rely on TLAB's having been filled and must do | |
| 4887 // so here just in case a scavenge did not happen. | |
| 4888 gch->ensure_parsability(false); // fill TLAB's, but no need to retire them | |
| 4889 // Update the saved marks which may affect the root scans. | |
| 4890 gch->save_marks(); | |
| 4891 | |
| 4892 { | |
| 4893 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact;) | |
| 4894 | |
| 4895 // Note on the role of the mod union table: | |
| 4896 // Since the marker in "markFromRoots" marks concurrently with | |
| 4897 // mutators, it is possible for some reachable objects not to have been | |
| 4898 // scanned. For instance, an only reference to an object A was | |
| 4899 // placed in object B after the marker scanned B. Unless B is rescanned, | |
| 4900 // A would be collected. Such updates to references in marked objects | |
| 4901 // are detected via the mod union table which is the set of all cards | |
| 4902 // dirtied since the first checkpoint in this GC cycle and prior to | |
| 4903 // the most recent young generation GC, minus those cleaned up by the | |
| 4904 // concurrent precleaning. | |
|
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|
4905 if (CMSParallelRemarkEnabled && CollectedHeap::use_parallel_gc_threads()) { |
| 0 | 4906 TraceTime t("Rescan (parallel) ", PrintGCDetails, false, gclog_or_tty); |
| 4907 do_remark_parallel(); | |
| 4908 } else { | |
| 4909 TraceTime t("Rescan (non-parallel) ", PrintGCDetails, false, | |
| 4910 gclog_or_tty); | |
| 4911 do_remark_non_parallel(); | |
| 4912 } | |
| 4913 } | |
| 4914 } else { | |
| 4915 assert(!asynch, "Can't have init_mark_was_synchronous in asynch mode"); | |
| 4916 // The initial mark was stop-world, so there's no rescanning to | |
| 4917 // do; go straight on to the next step below. | |
| 4918 } | |
| 4919 verify_work_stacks_empty(); | |
| 4920 verify_overflow_empty(); | |
| 4921 | |
| 4922 { | |
| 4923 NOT_PRODUCT(TraceTime ts("refProcessingWork", PrintGCDetails, false, gclog_or_tty);) | |
| 4924 refProcessingWork(asynch, clear_all_soft_refs); | |
| 4925 } | |
| 4926 verify_work_stacks_empty(); | |
| 4927 verify_overflow_empty(); | |
| 4928 | |
|
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4929 if (should_unload_classes()) { |
| 0 | 4930 CodeCache::gc_epilogue(); |
| 4931 } | |
|
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|
4932 JvmtiExport::gc_epilogue(); |
| 0 | 4933 |
| 4934 // If we encountered any (marking stack / work queue) overflow | |
| 4935 // events during the current CMS cycle, take appropriate | |
| 4936 // remedial measures, where possible, so as to try and avoid | |
| 4937 // recurrence of that condition. | |
| 4938 assert(_markStack.isEmpty(), "No grey objects"); | |
| 4939 size_t ser_ovflw = _ser_pmc_remark_ovflw + _ser_pmc_preclean_ovflw + | |
|
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|
4940 _ser_kac_ovflw + _ser_kac_preclean_ovflw; |
| 0 | 4941 if (ser_ovflw > 0) { |
| 4942 if (PrintCMSStatistics != 0) { | |
| 4943 gclog_or_tty->print_cr("Marking stack overflow (benign) " | |
|
452
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|
4944 "(pmc_pc="SIZE_FORMAT", pmc_rm="SIZE_FORMAT", kac="SIZE_FORMAT |
|
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|
4945 ", kac_preclean="SIZE_FORMAT")", |
| 0 | 4946 _ser_pmc_preclean_ovflw, _ser_pmc_remark_ovflw, |
|
452
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|
4947 _ser_kac_ovflw, _ser_kac_preclean_ovflw); |
| 0 | 4948 } |
| 4949 _markStack.expand(); | |
| 4950 _ser_pmc_remark_ovflw = 0; | |
| 4951 _ser_pmc_preclean_ovflw = 0; | |
|
452
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|
4952 _ser_kac_preclean_ovflw = 0; |
| 0 | 4953 _ser_kac_ovflw = 0; |
| 4954 } | |
| 4955 if (_par_pmc_remark_ovflw > 0 || _par_kac_ovflw > 0) { | |
| 4956 if (PrintCMSStatistics != 0) { | |
| 4957 gclog_or_tty->print_cr("Work queue overflow (benign) " | |
| 4958 "(pmc_rm="SIZE_FORMAT", kac="SIZE_FORMAT")", | |
| 4959 _par_pmc_remark_ovflw, _par_kac_ovflw); | |
| 4960 } | |
| 4961 _par_pmc_remark_ovflw = 0; | |
| 4962 _par_kac_ovflw = 0; | |
| 4963 } | |
| 4964 if (PrintCMSStatistics != 0) { | |
| 4965 if (_markStack._hit_limit > 0) { | |
| 4966 gclog_or_tty->print_cr(" (benign) Hit max stack size limit ("SIZE_FORMAT")", | |
| 4967 _markStack._hit_limit); | |
| 4968 } | |
| 4969 if (_markStack._failed_double > 0) { | |
| 4970 gclog_or_tty->print_cr(" (benign) Failed stack doubling ("SIZE_FORMAT")," | |
| 4971 " current capacity "SIZE_FORMAT, | |
| 4972 _markStack._failed_double, | |
| 4973 _markStack.capacity()); | |
| 4974 } | |
| 4975 } | |
| 4976 _markStack._hit_limit = 0; | |
| 4977 _markStack._failed_double = 0; | |
| 4978 | |
| 4979 if ((VerifyAfterGC || VerifyDuringGC) && | |
| 4980 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
| 4981 verify_after_remark(); | |
| 4982 } | |
| 4983 | |
| 4984 // Change under the freelistLocks. | |
| 4985 _collectorState = Sweeping; | |
| 4986 // Call isAllClear() under bitMapLock | |
|
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4987 assert(_modUnionTable.isAllClear(), |
|
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4988 "Should be clear by end of the final marking"); |
|
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4989 assert(_ct->klass_rem_set()->mod_union_is_clear(), |
|
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4990 "Should be clear by end of the final marking"); |
| 0 | 4991 if (UseAdaptiveSizePolicy) { |
| 4992 size_policy()->checkpoint_roots_final_end(gch->gc_cause()); | |
| 4993 } | |
| 4994 } | |
| 4995 | |
| 4996 // Parallel remark task | |
| 4997 class CMSParRemarkTask: public AbstractGangTask { | |
| 4998 CMSCollector* _collector; | |
| 4999 int _n_workers; | |
| 5000 CompactibleFreeListSpace* _cms_space; | |
| 5001 | |
| 5002 // The per-thread work queues, available here for stealing. | |
| 5003 OopTaskQueueSet* _task_queues; | |
| 5004 ParallelTaskTerminator _term; | |
| 5005 | |
| 5006 public: | |
|
4095
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|
5007 // A value of 0 passed to n_workers will cause the number of |
|
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|
5008 // workers to be taken from the active workers in the work gang. |
| 0 | 5009 CMSParRemarkTask(CMSCollector* collector, |
| 5010 CompactibleFreeListSpace* cms_space, | |
|
1833
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|
5011 int n_workers, FlexibleWorkGang* workers, |
| 0 | 5012 OopTaskQueueSet* task_queues): |
| 5013 AbstractGangTask("Rescan roots and grey objects in parallel"), | |
| 5014 _collector(collector), | |
|
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5015 _cms_space(cms_space), |
| 0 | 5016 _n_workers(n_workers), |
| 5017 _task_queues(task_queues), | |
|
1833
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|
5018 _term(n_workers, task_queues) { } |
| 0 | 5019 |
| 5020 OopTaskQueueSet* task_queues() { return _task_queues; } | |
| 5021 | |
| 5022 OopTaskQueue* work_queue(int i) { return task_queues()->queue(i); } | |
| 5023 | |
| 5024 ParallelTaskTerminator* terminator() { return &_term; } | |
|
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|
5025 int n_workers() { return _n_workers; } |
| 0 | 5026 |
|
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|
5027 void work(uint worker_id); |
| 0 | 5028 |
| 5029 private: | |
| 5030 // Work method in support of parallel rescan ... of young gen spaces | |
| 5031 void do_young_space_rescan(int i, Par_MarkRefsIntoAndScanClosure* cl, | |
| 5032 ContiguousSpace* space, | |
| 5033 HeapWord** chunk_array, size_t chunk_top); | |
| 5034 | |
| 5035 // ... of dirty cards in old space | |
| 5036 void do_dirty_card_rescan_tasks(CompactibleFreeListSpace* sp, int i, | |
| 5037 Par_MarkRefsIntoAndScanClosure* cl); | |
| 5038 | |
| 5039 // ... work stealing for the above | |
| 5040 void do_work_steal(int i, Par_MarkRefsIntoAndScanClosure* cl, int* seed); | |
| 5041 }; | |
| 5042 | |
|
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|
5043 class RemarkKlassClosure : public KlassClosure { |
|
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5044 CMKlassClosure _cm_klass_closure; |
|
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5045 public: |
|
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|
5046 RemarkKlassClosure(OopClosure* oop_closure) : _cm_klass_closure(oop_closure) {} |
|
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|
5047 void do_klass(Klass* k) { |
|
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5048 // Check if we have modified any oops in the Klass during the concurrent marking. |
|
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|
5049 if (k->has_accumulated_modified_oops()) { |
|
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|
5050 k->clear_accumulated_modified_oops(); |
|
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5051 |
|
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|
5052 // We could have transfered the current modified marks to the accumulated marks, |
|
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|
5053 // like we do with the Card Table to Mod Union Table. But it's not really necessary. |
|
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|
5054 } else if (k->has_modified_oops()) { |
|
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|
5055 // Don't clear anything, this info is needed by the next young collection. |
|
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|
5056 } else { |
|
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|
5057 // No modified oops in the Klass. |
|
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|
5058 return; |
|
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|
5059 } |
|
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|
5060 |
|
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|
5061 // The klass has modified fields, need to scan the klass. |
|
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|
5062 _cm_klass_closure.do_klass(k); |
|
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|
5063 } |
|
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|
5064 }; |
|
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|
5065 |
|
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|
5066 // work_queue(i) is passed to the closure |
|
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|
5067 // Par_MarkRefsIntoAndScanClosure. The "i" parameter |
|
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|
5068 // also is passed to do_dirty_card_rescan_tasks() and to |
|
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|
5069 // do_work_steal() to select the i-th task_queue. |
|
8b10f48633dc
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|
5070 |
|
4728
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|
5071 void CMSParRemarkTask::work(uint worker_id) { |
| 0 | 5072 elapsedTimer _timer; |
| 5073 ResourceMark rm; | |
| 5074 HandleMark hm; | |
| 5075 | |
| 5076 // ---------- rescan from roots -------------- | |
| 5077 _timer.start(); | |
| 5078 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 5079 Par_MarkRefsIntoAndScanClosure par_mrias_cl(_collector, | |
| 5080 _collector->_span, _collector->ref_processor(), | |
| 5081 &(_collector->_markBitMap), | |
|
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|
5082 work_queue(worker_id)); |
| 0 | 5083 |
| 5084 // Rescan young gen roots first since these are likely | |
| 5085 // coarsely partitioned and may, on that account, constitute | |
| 5086 // the critical path; thus, it's best to start off that | |
| 5087 // work first. | |
| 5088 // ---------- young gen roots -------------- | |
| 5089 { | |
| 5090 DefNewGeneration* dng = _collector->_young_gen->as_DefNewGeneration(); | |
| 5091 EdenSpace* eden_space = dng->eden(); | |
| 5092 ContiguousSpace* from_space = dng->from(); | |
| 5093 ContiguousSpace* to_space = dng->to(); | |
| 5094 | |
| 5095 HeapWord** eca = _collector->_eden_chunk_array; | |
| 5096 size_t ect = _collector->_eden_chunk_index; | |
| 5097 HeapWord** sca = _collector->_survivor_chunk_array; | |
| 5098 size_t sct = _collector->_survivor_chunk_index; | |
| 5099 | |
| 5100 assert(ect <= _collector->_eden_chunk_capacity, "out of bounds"); | |
| 5101 assert(sct <= _collector->_survivor_chunk_capacity, "out of bounds"); | |
| 5102 | |
|
4728
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|
5103 do_young_space_rescan(worker_id, &par_mrias_cl, to_space, NULL, 0); |
|
441e946dc1af
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jmasa
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|
5104 do_young_space_rescan(worker_id, &par_mrias_cl, from_space, sca, sct); |
|
441e946dc1af
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|
5105 do_young_space_rescan(worker_id, &par_mrias_cl, eden_space, eca, ect); |
| 0 | 5106 |
| 5107 _timer.stop(); | |
| 5108 if (PrintCMSStatistics != 0) { | |
| 5109 gclog_or_tty->print_cr( | |
| 5110 "Finished young gen rescan work in %dth thread: %3.3f sec", | |
|
4728
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|
5111 worker_id, _timer.seconds()); |
| 0 | 5112 } |
| 5113 } | |
| 5114 | |
| 5115 // ---------- remaining roots -------------- | |
| 5116 _timer.reset(); | |
| 5117 _timer.start(); | |
| 5118 gch->gen_process_strong_roots(_collector->_cmsGen->level(), | |
| 5119 false, // yg was scanned above | |
|
989
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
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diff
changeset
|
5120 false, // this is parallel code |
|
6725
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|
5121 false, // not scavenging |
| 0 | 5122 SharedHeap::ScanningOption(_collector->CMSCollector::roots_scanning_options()), |
|
989
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
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diff
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|
5123 &par_mrias_cl, |
|
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
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diff
changeset
|
5124 true, // walk all of code cache if (so & SO_CodeCache) |
|
6725
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|
5125 NULL, |
|
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|
5126 NULL); // The dirty klasses will be handled below |
|
989
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diff
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|
5127 assert(_collector->should_unload_classes() |
|
148e5441d916
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|
5128 || (_collector->CMSCollector::roots_scanning_options() & SharedHeap::SO_CodeCache), |
|
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jrose
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|
5129 "if we didn't scan the code cache, we have to be ready to drop nmethods with expired weak oops"); |
| 0 | 5130 _timer.stop(); |
| 5131 if (PrintCMSStatistics != 0) { | |
| 5132 gclog_or_tty->print_cr( | |
| 5133 "Finished remaining root rescan work in %dth thread: %3.3f sec", | |
|
4728
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|
5134 worker_id, _timer.seconds()); |
| 0 | 5135 } |
| 5136 | |
|
6725
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|
5137 // ---------- unhandled CLD scanning ---------- |
|
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|
5138 if (worker_id == 0) { // Single threaded at the moment. |
|
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|
5139 _timer.reset(); |
|
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|
5140 _timer.start(); |
|
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|
5141 |
|
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|
5142 // Scan all new class loader data objects and new dependencies that were |
|
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|
5143 // introduced during concurrent marking. |
|
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|
5144 ResourceMark rm; |
|
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|
5145 GrowableArray<ClassLoaderData*>* array = ClassLoaderDataGraph::new_clds(); |
|
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|
5146 for (int i = 0; i < array->length(); i++) { |
|
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|
5147 par_mrias_cl.do_class_loader_data(array->at(i)); |
|
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|
5148 } |
|
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|
5149 |
|
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|
5150 // We don't need to keep track of new CLDs anymore. |
|
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|
5151 ClassLoaderDataGraph::remember_new_clds(false); |
|
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|
5152 |
|
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|
5153 _timer.stop(); |
|
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|
5154 if (PrintCMSStatistics != 0) { |
|
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|
5155 gclog_or_tty->print_cr( |
|
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|
5156 "Finished unhandled CLD scanning work in %dth thread: %3.3f sec", |
|
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|
5157 worker_id, _timer.seconds()); |
|
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|
5158 } |
|
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|
5159 } |
|
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|
5160 |
|
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5161 // ---------- dirty klass scanning ---------- |
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5162 if (worker_id == 0) { // Single threaded at the moment. |
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5163 _timer.reset(); |
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5164 _timer.start(); |
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5165 |
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5166 // Scan all classes that was dirtied during the concurrent marking phase. |
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5167 RemarkKlassClosure remark_klass_closure(&par_mrias_cl); |
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5168 ClassLoaderDataGraph::classes_do(&remark_klass_closure); |
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5169 |
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5170 _timer.stop(); |
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5171 if (PrintCMSStatistics != 0) { |
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5172 gclog_or_tty->print_cr( |
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5173 "Finished dirty klass scanning work in %dth thread: %3.3f sec", |
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5174 worker_id, _timer.seconds()); |
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5175 } |
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5176 } |
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5177 |
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5178 // We might have added oops to ClassLoaderData::_handles during the |
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5179 // concurrent marking phase. These oops point to newly allocated objects |
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5180 // that are guaranteed to be kept alive. Either by the direct allocation |
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5181 // code, or when the young collector processes the strong roots. Hence, |
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5182 // we don't have to revisit the _handles block during the remark phase. |
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5183 |
| 0 | 5184 // ---------- rescan dirty cards ------------ |
| 5185 _timer.reset(); | |
| 5186 _timer.start(); | |
| 5187 | |
| 5188 // Do the rescan tasks for each of the two spaces | |
|
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5189 // (cms_space) in turn. |
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5190 // "worker_id" is passed to select the task_queue for "worker_id" |
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5191 do_dirty_card_rescan_tasks(_cms_space, worker_id, &par_mrias_cl); |
| 0 | 5192 _timer.stop(); |
| 5193 if (PrintCMSStatistics != 0) { | |
| 5194 gclog_or_tty->print_cr( | |
| 5195 "Finished dirty card rescan work in %dth thread: %3.3f sec", | |
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5196 worker_id, _timer.seconds()); |
| 0 | 5197 } |
| 5198 | |
| 5199 // ---------- steal work from other threads ... | |
| 5200 // ---------- ... and drain overflow list. | |
| 5201 _timer.reset(); | |
| 5202 _timer.start(); | |
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5203 do_work_steal(worker_id, &par_mrias_cl, _collector->hash_seed(worker_id)); |
| 0 | 5204 _timer.stop(); |
| 5205 if (PrintCMSStatistics != 0) { | |
| 5206 gclog_or_tty->print_cr( | |
| 5207 "Finished work stealing in %dth thread: %3.3f sec", | |
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5208 worker_id, _timer.seconds()); |
| 0 | 5209 } |
| 5210 } | |
| 5211 | |
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5212 // Note that parameter "i" is not used. |
| 0 | 5213 void |
| 5214 CMSParRemarkTask::do_young_space_rescan(int i, | |
| 5215 Par_MarkRefsIntoAndScanClosure* cl, ContiguousSpace* space, | |
| 5216 HeapWord** chunk_array, size_t chunk_top) { | |
| 5217 // Until all tasks completed: | |
| 5218 // . claim an unclaimed task | |
| 5219 // . compute region boundaries corresponding to task claimed | |
| 5220 // using chunk_array | |
| 5221 // . par_oop_iterate(cl) over that region | |
| 5222 | |
| 5223 ResourceMark rm; | |
| 5224 HandleMark hm; | |
| 5225 | |
| 5226 SequentialSubTasksDone* pst = space->par_seq_tasks(); | |
| 5227 assert(pst->valid(), "Uninitialized use?"); | |
| 5228 | |
|
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5229 uint nth_task = 0; |
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5230 uint n_tasks = pst->n_tasks(); |
| 0 | 5231 |
| 5232 HeapWord *start, *end; | |
| 5233 while (!pst->is_task_claimed(/* reference */ nth_task)) { | |
| 5234 // We claimed task # nth_task; compute its boundaries. | |
| 5235 if (chunk_top == 0) { // no samples were taken | |
| 5236 assert(nth_task == 0 && n_tasks == 1, "Can have only 1 EdenSpace task"); | |
| 5237 start = space->bottom(); | |
| 5238 end = space->top(); | |
| 5239 } else if (nth_task == 0) { | |
| 5240 start = space->bottom(); | |
| 5241 end = chunk_array[nth_task]; | |
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5242 } else if (nth_task < (uint)chunk_top) { |
| 0 | 5243 assert(nth_task >= 1, "Control point invariant"); |
| 5244 start = chunk_array[nth_task - 1]; | |
| 5245 end = chunk_array[nth_task]; | |
| 5246 } else { | |
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5247 assert(nth_task == (uint)chunk_top, "Control point invariant"); |
| 0 | 5248 start = chunk_array[chunk_top - 1]; |
| 5249 end = space->top(); | |
| 5250 } | |
| 5251 MemRegion mr(start, end); | |
| 5252 // Verify that mr is in space | |
| 5253 assert(mr.is_empty() || space->used_region().contains(mr), | |
| 5254 "Should be in space"); | |
| 5255 // Verify that "start" is an object boundary | |
| 5256 assert(mr.is_empty() || oop(mr.start())->is_oop(), | |
| 5257 "Should be an oop"); | |
| 5258 space->par_oop_iterate(mr, cl); | |
| 5259 } | |
| 5260 pst->all_tasks_completed(); | |
| 5261 } | |
| 5262 | |
| 5263 void | |
| 5264 CMSParRemarkTask::do_dirty_card_rescan_tasks( | |
| 5265 CompactibleFreeListSpace* sp, int i, | |
| 5266 Par_MarkRefsIntoAndScanClosure* cl) { | |
| 5267 // Until all tasks completed: | |
| 5268 // . claim an unclaimed task | |
| 5269 // . compute region boundaries corresponding to task claimed | |
| 5270 // . transfer dirty bits ct->mut for that region | |
| 5271 // . apply rescanclosure to dirty mut bits for that region | |
| 5272 | |
| 5273 ResourceMark rm; | |
| 5274 HandleMark hm; | |
| 5275 | |
| 5276 OopTaskQueue* work_q = work_queue(i); | |
| 5277 ModUnionClosure modUnionClosure(&(_collector->_modUnionTable)); | |
| 5278 // CAUTION! CAUTION! CAUTION! CAUTION! CAUTION! CAUTION! CAUTION! | |
| 5279 // CAUTION: This closure has state that persists across calls to | |
| 5280 // the work method dirty_range_iterate_clear() in that it has | |
| 5281 // imbedded in it a (subtype of) UpwardsObjectClosure. The | |
| 5282 // use of that state in the imbedded UpwardsObjectClosure instance | |
| 5283 // assumes that the cards are always iterated (even if in parallel | |
| 5284 // by several threads) in monotonically increasing order per each | |
| 5285 // thread. This is true of the implementation below which picks | |
| 5286 // card ranges (chunks) in monotonically increasing order globally | |
| 5287 // and, a-fortiori, in monotonically increasing order per thread | |
| 5288 // (the latter order being a subsequence of the former). | |
| 5289 // If the work code below is ever reorganized into a more chaotic | |
| 5290 // work-partitioning form than the current "sequential tasks" | |
| 5291 // paradigm, the use of that persistent state will have to be | |
| 5292 // revisited and modified appropriately. See also related | |
| 5293 // bug 4756801 work on which should examine this code to make | |
| 5294 // sure that the changes there do not run counter to the | |
| 5295 // assumptions made here and necessary for correctness and | |
| 5296 // efficiency. Note also that this code might yield inefficient | |
| 5297 // behaviour in the case of very large objects that span one or | |
| 5298 // more work chunks. Such objects would potentially be scanned | |
| 5299 // several times redundantly. Work on 4756801 should try and | |
| 5300 // address that performance anomaly if at all possible. XXX | |
| 5301 MemRegion full_span = _collector->_span; | |
| 5302 CMSBitMap* bm = &(_collector->_markBitMap); // shared | |
| 5303 MarkFromDirtyCardsClosure | |
| 5304 greyRescanClosure(_collector, full_span, // entire span of interest | |
|
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5305 sp, bm, work_q, cl); |
| 0 | 5306 |
| 5307 SequentialSubTasksDone* pst = sp->conc_par_seq_tasks(); | |
| 5308 assert(pst->valid(), "Uninitialized use?"); | |
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5309 uint nth_task = 0; |
| 0 | 5310 const int alignment = CardTableModRefBS::card_size * BitsPerWord; |
| 5311 MemRegion span = sp->used_region(); | |
| 5312 HeapWord* start_addr = span.start(); | |
| 5313 HeapWord* end_addr = (HeapWord*)round_to((intptr_t)span.end(), | |
| 5314 alignment); | |
| 5315 const size_t chunk_size = sp->rescan_task_size(); // in HeapWord units | |
| 5316 assert((HeapWord*)round_to((intptr_t)start_addr, alignment) == | |
| 5317 start_addr, "Check alignment"); | |
| 5318 assert((size_t)round_to((intptr_t)chunk_size, alignment) == | |
| 5319 chunk_size, "Check alignment"); | |
| 5320 | |
| 5321 while (!pst->is_task_claimed(/* reference */ nth_task)) { | |
| 5322 // Having claimed the nth_task, compute corresponding mem-region, | |
| 5323 // which is a-fortiori aligned correctly (i.e. at a MUT bopundary). | |
| 5324 // The alignment restriction ensures that we do not need any | |
| 5325 // synchronization with other gang-workers while setting or | |
| 5326 // clearing bits in thus chunk of the MUT. | |
| 5327 MemRegion this_span = MemRegion(start_addr + nth_task*chunk_size, | |
| 5328 start_addr + (nth_task+1)*chunk_size); | |
| 5329 // The last chunk's end might be way beyond end of the | |
| 5330 // used region. In that case pull back appropriately. | |
| 5331 if (this_span.end() > end_addr) { | |
| 5332 this_span.set_end(end_addr); | |
| 5333 assert(!this_span.is_empty(), "Program logic (calculation of n_tasks)"); | |
| 5334 } | |
| 5335 // Iterate over the dirty cards covering this chunk, marking them | |
| 5336 // precleaned, and setting the corresponding bits in the mod union | |
| 5337 // table. Since we have been careful to partition at Card and MUT-word | |
| 5338 // boundaries no synchronization is needed between parallel threads. | |
| 5339 _collector->_ct->ct_bs()->dirty_card_iterate(this_span, | |
| 5340 &modUnionClosure); | |
| 5341 | |
| 5342 // Having transferred these marks into the modUnionTable, | |
| 5343 // rescan the marked objects on the dirty cards in the modUnionTable. | |
| 5344 // Even if this is at a synchronous collection, the initial marking | |
| 5345 // may have been done during an asynchronous collection so there | |
| 5346 // may be dirty bits in the mod-union table. | |
| 5347 _collector->_modUnionTable.dirty_range_iterate_clear( | |
| 5348 this_span, &greyRescanClosure); | |
| 5349 _collector->_modUnionTable.verifyNoOneBitsInRange( | |
| 5350 this_span.start(), | |
| 5351 this_span.end()); | |
| 5352 } | |
| 5353 pst->all_tasks_completed(); // declare that i am done | |
| 5354 } | |
| 5355 | |
| 5356 // . see if we can share work_queues with ParNew? XXX | |
| 5357 void | |
| 5358 CMSParRemarkTask::do_work_steal(int i, Par_MarkRefsIntoAndScanClosure* cl, | |
| 5359 int* seed) { | |
| 5360 OopTaskQueue* work_q = work_queue(i); | |
| 5361 NOT_PRODUCT(int num_steals = 0;) | |
| 5362 oop obj_to_scan; | |
| 5363 CMSBitMap* bm = &(_collector->_markBitMap); | |
| 5364 | |
| 5365 while (true) { | |
| 5366 // Completely finish any left over work from (an) earlier round(s) | |
| 5367 cl->trim_queue(0); | |
|
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5368 size_t num_from_overflow_list = MIN2((size_t)(work_q->max_elems() - work_q->size())/4, |
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5369 (size_t)ParGCDesiredObjsFromOverflowList); |
| 0 | 5370 // Now check if there's any work in the overflow list |
|
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5371 // Passing ParallelGCThreads as the third parameter, no_of_gc_threads, |
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5372 // only affects the number of attempts made to get work from the |
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5373 // overflow list and does not affect the number of workers. Just |
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5374 // pass ParallelGCThreads so this behavior is unchanged. |
| 0 | 5375 if (_collector->par_take_from_overflow_list(num_from_overflow_list, |
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5376 work_q, |
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5377 ParallelGCThreads)) { |
| 0 | 5378 // found something in global overflow list; |
| 5379 // not yet ready to go stealing work from others. | |
| 5380 // We'd like to assert(work_q->size() != 0, ...) | |
| 5381 // because we just took work from the overflow list, | |
| 5382 // but of course we can't since all of that could have | |
| 5383 // been already stolen from us. | |
| 5384 // "He giveth and He taketh away." | |
| 5385 continue; | |
| 5386 } | |
| 5387 // Verify that we have no work before we resort to stealing | |
| 5388 assert(work_q->size() == 0, "Have work, shouldn't steal"); | |
| 5389 // Try to steal from other queues that have work | |
| 5390 if (task_queues()->steal(i, seed, /* reference */ obj_to_scan)) { | |
| 5391 NOT_PRODUCT(num_steals++;) | |
| 5392 assert(obj_to_scan->is_oop(), "Oops, not an oop!"); | |
| 5393 assert(bm->isMarked((HeapWord*)obj_to_scan), "Stole an unmarked oop?"); | |
| 5394 // Do scanning work | |
| 5395 obj_to_scan->oop_iterate(cl); | |
| 5396 // Loop around, finish this work, and try to steal some more | |
| 5397 } else if (terminator()->offer_termination()) { | |
| 5398 break; // nirvana from the infinite cycle | |
| 5399 } | |
| 5400 } | |
| 5401 NOT_PRODUCT( | |
| 5402 if (PrintCMSStatistics != 0) { | |
| 5403 gclog_or_tty->print("\n\t(%d: stole %d oops)", i, num_steals); | |
| 5404 } | |
| 5405 ) | |
| 5406 assert(work_q->size() == 0 && _collector->overflow_list_is_empty(), | |
| 5407 "Else our work is not yet done"); | |
| 5408 } | |
| 5409 | |
| 5410 // Return a thread-local PLAB recording array, as appropriate. | |
| 5411 void* CMSCollector::get_data_recorder(int thr_num) { | |
| 5412 if (_survivor_plab_array != NULL && | |
| 5413 (CMSPLABRecordAlways || | |
| 5414 (_collectorState > Marking && _collectorState < FinalMarking))) { | |
| 5415 assert(thr_num < (int)ParallelGCThreads, "thr_num is out of bounds"); | |
| 5416 ChunkArray* ca = &_survivor_plab_array[thr_num]; | |
| 5417 ca->reset(); // clear it so that fresh data is recorded | |
| 5418 return (void*) ca; | |
| 5419 } else { | |
| 5420 return NULL; | |
| 5421 } | |
| 5422 } | |
| 5423 | |
| 5424 // Reset all the thread-local PLAB recording arrays | |
| 5425 void CMSCollector::reset_survivor_plab_arrays() { | |
| 5426 for (uint i = 0; i < ParallelGCThreads; i++) { | |
| 5427 _survivor_plab_array[i].reset(); | |
| 5428 } | |
| 5429 } | |
| 5430 | |
| 5431 // Merge the per-thread plab arrays into the global survivor chunk | |
| 5432 // array which will provide the partitioning of the survivor space | |
| 5433 // for CMS rescan. | |
|
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5434 void CMSCollector::merge_survivor_plab_arrays(ContiguousSpace* surv, |
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5435 int no_of_gc_threads) { |
| 0 | 5436 assert(_survivor_plab_array != NULL, "Error"); |
| 5437 assert(_survivor_chunk_array != NULL, "Error"); | |
| 5438 assert(_collectorState == FinalMarking, "Error"); | |
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5439 for (int j = 0; j < no_of_gc_threads; j++) { |
| 0 | 5440 _cursor[j] = 0; |
| 5441 } | |
| 5442 HeapWord* top = surv->top(); | |
| 5443 size_t i; | |
| 5444 for (i = 0; i < _survivor_chunk_capacity; i++) { // all sca entries | |
| 5445 HeapWord* min_val = top; // Higher than any PLAB address | |
| 5446 uint min_tid = 0; // position of min_val this round | |
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5447 for (int j = 0; j < no_of_gc_threads; j++) { |
| 0 | 5448 ChunkArray* cur_sca = &_survivor_plab_array[j]; |
| 5449 if (_cursor[j] == cur_sca->end()) { | |
| 5450 continue; | |
| 5451 } | |
| 5452 assert(_cursor[j] < cur_sca->end(), "ctl pt invariant"); | |
| 5453 HeapWord* cur_val = cur_sca->nth(_cursor[j]); | |
| 5454 assert(surv->used_region().contains(cur_val), "Out of bounds value"); | |
| 5455 if (cur_val < min_val) { | |
| 5456 min_tid = j; | |
| 5457 min_val = cur_val; | |
| 5458 } else { | |
| 5459 assert(cur_val < top, "All recorded addresses should be less"); | |
| 5460 } | |
| 5461 } | |
| 5462 // At this point min_val and min_tid are respectively | |
| 5463 // the least address in _survivor_plab_array[j]->nth(_cursor[j]) | |
| 5464 // and the thread (j) that witnesses that address. | |
| 5465 // We record this address in the _survivor_chunk_array[i] | |
| 5466 // and increment _cursor[min_tid] prior to the next round i. | |
| 5467 if (min_val == top) { | |
| 5468 break; | |
| 5469 } | |
| 5470 _survivor_chunk_array[i] = min_val; | |
| 5471 _cursor[min_tid]++; | |
| 5472 } | |
| 5473 // We are all done; record the size of the _survivor_chunk_array | |
| 5474 _survivor_chunk_index = i; // exclusive: [0, i) | |
| 5475 if (PrintCMSStatistics > 0) { | |
| 5476 gclog_or_tty->print(" (Survivor:" SIZE_FORMAT "chunks) ", i); | |
| 5477 } | |
| 5478 // Verify that we used up all the recorded entries | |
| 5479 #ifdef ASSERT | |
| 5480 size_t total = 0; | |
|
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|
5481 for (int j = 0; j < no_of_gc_threads; j++) { |
| 0 | 5482 assert(_cursor[j] == _survivor_plab_array[j].end(), "Ctl pt invariant"); |
| 5483 total += _cursor[j]; | |
| 5484 } | |
| 5485 assert(total == _survivor_chunk_index, "Ctl Pt Invariant"); | |
| 5486 // Check that the merged array is in sorted order | |
| 5487 if (total > 0) { | |
| 5488 for (size_t i = 0; i < total - 1; i++) { | |
| 5489 if (PrintCMSStatistics > 0) { | |
| 5490 gclog_or_tty->print(" (chunk" SIZE_FORMAT ":" INTPTR_FORMAT ") ", | |
| 5491 i, _survivor_chunk_array[i]); | |
| 5492 } | |
| 5493 assert(_survivor_chunk_array[i] < _survivor_chunk_array[i+1], | |
| 5494 "Not sorted"); | |
| 5495 } | |
| 5496 } | |
| 5497 #endif // ASSERT | |
| 5498 } | |
| 5499 | |
| 5500 // Set up the space's par_seq_tasks structure for work claiming | |
| 5501 // for parallel rescan of young gen. | |
| 5502 // See ParRescanTask where this is currently used. | |
| 5503 void | |
| 5504 CMSCollector:: | |
| 5505 initialize_sequential_subtasks_for_young_gen_rescan(int n_threads) { | |
| 5506 assert(n_threads > 0, "Unexpected n_threads argument"); | |
| 5507 DefNewGeneration* dng = (DefNewGeneration*)_young_gen; | |
| 5508 | |
| 5509 // Eden space | |
| 5510 { | |
| 5511 SequentialSubTasksDone* pst = dng->eden()->par_seq_tasks(); | |
| 5512 assert(!pst->valid(), "Clobbering existing data?"); | |
| 5513 // Each valid entry in [0, _eden_chunk_index) represents a task. | |
| 5514 size_t n_tasks = _eden_chunk_index + 1; | |
| 5515 assert(n_tasks == 1 || _eden_chunk_array != NULL, "Error"); | |
|
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|
5516 // Sets the condition for completion of the subtask (how many threads |
|
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|
5517 // need to finish in order to be done). |
|
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|
5518 pst->set_n_threads(n_threads); |
| 0 | 5519 pst->set_n_tasks((int)n_tasks); |
| 5520 } | |
| 5521 | |
| 5522 // Merge the survivor plab arrays into _survivor_chunk_array | |
| 5523 if (_survivor_plab_array != NULL) { | |
|
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|
5524 merge_survivor_plab_arrays(dng->from(), n_threads); |
| 0 | 5525 } else { |
| 5526 assert(_survivor_chunk_index == 0, "Error"); | |
| 5527 } | |
| 5528 | |
| 5529 // To space | |
| 5530 { | |
| 5531 SequentialSubTasksDone* pst = dng->to()->par_seq_tasks(); | |
| 5532 assert(!pst->valid(), "Clobbering existing data?"); | |
|
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|
5533 // Sets the condition for completion of the subtask (how many threads |
|
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|
5534 // need to finish in order to be done). |
|
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|
5535 pst->set_n_threads(n_threads); |
| 0 | 5536 pst->set_n_tasks(1); |
| 5537 assert(pst->valid(), "Error"); | |
| 5538 } | |
| 5539 | |
| 5540 // From space | |
| 5541 { | |
| 5542 SequentialSubTasksDone* pst = dng->from()->par_seq_tasks(); | |
| 5543 assert(!pst->valid(), "Clobbering existing data?"); | |
| 5544 size_t n_tasks = _survivor_chunk_index + 1; | |
| 5545 assert(n_tasks == 1 || _survivor_chunk_array != NULL, "Error"); | |
|
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|
5546 // Sets the condition for completion of the subtask (how many threads |
|
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|
5547 // need to finish in order to be done). |
|
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|
5548 pst->set_n_threads(n_threads); |
| 0 | 5549 pst->set_n_tasks((int)n_tasks); |
| 5550 assert(pst->valid(), "Error"); | |
| 5551 } | |
| 5552 } | |
| 5553 | |
| 5554 // Parallel version of remark | |
| 5555 void CMSCollector::do_remark_parallel() { | |
| 5556 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
|
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|
5557 FlexibleWorkGang* workers = gch->workers(); |
| 0 | 5558 assert(workers != NULL, "Need parallel worker threads."); |
|
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|
5559 // Choose to use the number of GC workers most recently set |
|
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|
5560 // into "active_workers". If active_workers is not set, set it |
|
bca17e38de00
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|
5561 // to ParallelGCThreads. |
|
bca17e38de00
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|
5562 int n_workers = workers->active_workers(); |
|
bca17e38de00
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diff
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|
5563 if (n_workers == 0) { |
|
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diff
changeset
|
5564 assert(n_workers > 0, "Should have been set during scavenge"); |
|
bca17e38de00
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jmasa
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|
5565 n_workers = ParallelGCThreads; |
|
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|
5566 workers->set_active_workers(n_workers); |
|
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|
5567 } |
| 0 | 5568 CompactibleFreeListSpace* cms_space = _cmsGen->cmsSpace(); |
| 5569 | |
| 5570 CMSParRemarkTask tsk(this, | |
|
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|
5571 cms_space, |
| 0 | 5572 n_workers, workers, task_queues()); |
| 5573 | |
| 5574 // Set up for parallel process_strong_roots work. | |
| 5575 gch->set_par_threads(n_workers); | |
| 5576 // We won't be iterating over the cards in the card table updating | |
| 5577 // the younger_gen cards, so we shouldn't call the following else | |
| 5578 // the verification code as well as subsequent younger_refs_iterate | |
| 5579 // code would get confused. XXX | |
| 5580 // gch->rem_set()->prepare_for_younger_refs_iterate(true); // parallel | |
| 5581 | |
| 5582 // The young gen rescan work will not be done as part of | |
| 5583 // process_strong_roots (which currently doesn't knw how to | |
| 5584 // parallelize such a scan), but rather will be broken up into | |
| 5585 // a set of parallel tasks (via the sampling that the [abortable] | |
| 5586 // preclean phase did of EdenSpace, plus the [two] tasks of | |
| 5587 // scanning the [two] survivor spaces. Further fine-grain | |
| 5588 // parallelization of the scanning of the survivor spaces | |
| 5589 // themselves, and of precleaning of the younger gen itself | |
| 5590 // is deferred to the future. | |
| 5591 initialize_sequential_subtasks_for_young_gen_rescan(n_workers); | |
| 5592 | |
| 5593 // The dirty card rescan work is broken up into a "sequence" | |
| 5594 // of parallel tasks (per constituent space) that are dynamically | |
| 5595 // claimed by the parallel threads. | |
| 5596 cms_space->initialize_sequential_subtasks_for_rescan(n_workers); | |
| 5597 | |
| 5598 // It turns out that even when we're using 1 thread, doing the work in a | |
| 5599 // separate thread causes wide variance in run times. We can't help this | |
| 5600 // in the multi-threaded case, but we special-case n=1 here to get | |
| 5601 // repeatable measurements of the 1-thread overhead of the parallel code. | |
| 5602 if (n_workers > 1) { | |
|
2369
92da084fefc9
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2365
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changeset
|
5603 // Make refs discovery MT-safe, if it isn't already: it may not |
|
92da084fefc9
6668573: CMS: reference processing crash if ParallelCMSThreads > ParallelGCThreads
ysr
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diff
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|
5604 // necessarily be so, since it's possible that we are doing |
|
92da084fefc9
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|
5605 // ST marking. |
|
92da084fefc9
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|
5606 ReferenceProcessorMTDiscoveryMutator mt(ref_processor(), true); |
|
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|
5607 GenCollectedHeap::StrongRootsScope srs(gch); |
| 0 | 5608 workers->run_task(&tsk); |
| 5609 } else { | |
|
4876
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|
5610 ReferenceProcessorMTDiscoveryMutator mt(ref_processor(), false); |
|
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|
5611 GenCollectedHeap::StrongRootsScope srs(gch); |
| 0 | 5612 tsk.work(0); |
| 5613 } | |
|
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|
5614 |
| 0 | 5615 gch->set_par_threads(0); // 0 ==> non-parallel. |
| 5616 // restore, single-threaded for now, any preserved marks | |
| 5617 // as a result of work_q overflow | |
| 5618 restore_preserved_marks_if_any(); | |
| 5619 } | |
| 5620 | |
| 5621 // Non-parallel version of remark | |
| 5622 void CMSCollector::do_remark_non_parallel() { | |
| 5623 ResourceMark rm; | |
| 5624 HandleMark hm; | |
| 5625 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
|
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|
5626 ReferenceProcessorMTDiscoveryMutator mt(ref_processor(), false); |
|
be649fefcdc2
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stefank
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|
5627 |
| 0 | 5628 MarkRefsIntoAndScanClosure |
|
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|
5629 mrias_cl(_span, ref_processor(), &_markBitMap, NULL /* not precleaning */, |
|
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|
5630 &_markStack, this, |
| 0 | 5631 false /* should_yield */, false /* not precleaning */); |
| 5632 MarkFromDirtyCardsClosure | |
| 5633 markFromDirtyCardsClosure(this, _span, | |
| 5634 NULL, // space is set further below | |
|
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|
5635 &_markBitMap, &_markStack, &mrias_cl); |
| 0 | 5636 { |
| 5637 TraceTime t("grey object rescan", PrintGCDetails, false, gclog_or_tty); | |
|
342
37f87013dfd8
6711316: Open source the Garbage-First garbage collector
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143
diff
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|
5638 // Iterate over the dirty cards, setting the corresponding bits in the |
|
37f87013dfd8
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diff
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|
5639 // mod union table. |
| 0 | 5640 { |
| 5641 ModUnionClosure modUnionClosure(&_modUnionTable); | |
| 5642 _ct->ct_bs()->dirty_card_iterate( | |
| 5643 _cmsGen->used_region(), | |
| 5644 &modUnionClosure); | |
| 5645 } | |
| 5646 // Having transferred these marks into the modUnionTable, we just need | |
| 5647 // to rescan the marked objects on the dirty cards in the modUnionTable. | |
| 5648 // The initial marking may have been done during an asynchronous | |
| 5649 // collection so there may be dirty bits in the mod-union table. | |
| 5650 const int alignment = | |
| 5651 CardTableModRefBS::card_size * BitsPerWord; | |
| 5652 { | |
| 5653 // ... First handle dirty cards in CMS gen | |
| 5654 markFromDirtyCardsClosure.set_space(_cmsGen->cmsSpace()); | |
| 5655 MemRegion ur = _cmsGen->used_region(); | |
| 5656 HeapWord* lb = ur.start(); | |
| 5657 HeapWord* ub = (HeapWord*)round_to((intptr_t)ur.end(), alignment); | |
| 5658 MemRegion cms_span(lb, ub); | |
| 5659 _modUnionTable.dirty_range_iterate_clear(cms_span, | |
| 5660 &markFromDirtyCardsClosure); | |
| 5661 verify_work_stacks_empty(); | |
| 5662 if (PrintCMSStatistics != 0) { | |
| 5663 gclog_or_tty->print(" (re-scanned "SIZE_FORMAT" dirty cards in cms gen) ", | |
| 5664 markFromDirtyCardsClosure.num_dirty_cards()); | |
| 5665 } | |
| 5666 } | |
| 5667 } | |
| 5668 if (VerifyDuringGC && | |
| 5669 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
| 5670 HandleMark hm; // Discard invalid handles created during verification | |
|
6865
4202510ee0fe
8000831: Heap verification output incorrect/incomplete
johnc
parents:
6787
diff
changeset
|
5671 Universe::verify(); |
| 0 | 5672 } |
| 5673 { | |
| 5674 TraceTime t("root rescan", PrintGCDetails, false, gclog_or_tty); | |
| 5675 | |
| 5676 verify_work_stacks_empty(); | |
| 5677 | |
| 5678 gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel. | |
|
989
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6863023: need non-perm oops in code cache for JSR 292
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diff
changeset
|
5679 GenCollectedHeap::StrongRootsScope srs(gch); |
| 0 | 5680 gch->gen_process_strong_roots(_cmsGen->level(), |
| 5681 true, // younger gens as roots | |
|
989
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6863023: need non-perm oops in code cache for JSR 292
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diff
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|
5682 false, // use the local StrongRootsScope |
|
6725
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|
5683 false, // not scavenging |
| 0 | 5684 SharedHeap::ScanningOption(roots_scanning_options()), |
|
989
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6863023: need non-perm oops in code cache for JSR 292
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diff
changeset
|
5685 &mrias_cl, |
|
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
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diff
changeset
|
5686 true, // walk code active on stacks |
|
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|
5687 NULL, |
|
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|
5688 NULL); // The dirty klasses will be handled below |
|
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|
5689 |
|
989
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diff
changeset
|
5690 assert(should_unload_classes() |
|
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
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diff
changeset
|
5691 || (roots_scanning_options() & SharedHeap::SO_CodeCache), |
|
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diff
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|
5692 "if we didn't scan the code cache, we have to be ready to drop nmethods with expired weak oops"); |
| 0 | 5693 } |
|
6725
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|
5694 |
|
da91efe96a93
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changeset
|
5695 { |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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diff
changeset
|
5696 TraceTime t("visit unhandled CLDs", PrintGCDetails, false, gclog_or_tty); |
|
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|
5697 |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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changeset
|
5698 verify_work_stacks_empty(); |
|
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diff
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|
5699 |
|
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|
5700 // Scan all class loader data objects that might have been introduced |
|
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|
5701 // during concurrent marking. |
|
da91efe96a93
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diff
changeset
|
5702 ResourceMark rm; |
|
da91efe96a93
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|
5703 GrowableArray<ClassLoaderData*>* array = ClassLoaderDataGraph::new_clds(); |
|
da91efe96a93
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coleenp
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|
5704 for (int i = 0; i < array->length(); i++) { |
|
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diff
changeset
|
5705 mrias_cl.do_class_loader_data(array->at(i)); |
|
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6197
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|
5706 } |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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changeset
|
5707 |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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changeset
|
5708 // We don't need to keep track of new CLDs anymore. |
|
da91efe96a93
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coleenp
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6197
diff
changeset
|
5709 ClassLoaderDataGraph::remember_new_clds(false); |
|
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6964458: Reimplement class meta-data storage to use native memory
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6197
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|
5710 |
|
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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changeset
|
5711 verify_work_stacks_empty(); |
|
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|
5712 } |
|
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changeset
|
5713 |
|
da91efe96a93
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6197
diff
changeset
|
5714 { |
|
da91efe96a93
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diff
changeset
|
5715 TraceTime t("dirty klass scan", PrintGCDetails, false, gclog_or_tty); |
|
da91efe96a93
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|
5716 |
|
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changeset
|
5717 verify_work_stacks_empty(); |
|
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|
5718 |
|
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5719 RemarkKlassClosure remark_klass_closure(&mrias_cl); |
|
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5720 ClassLoaderDataGraph::classes_do(&remark_klass_closure); |
|
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|
5721 |
|
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|
5722 verify_work_stacks_empty(); |
|
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|
5723 } |
|
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|
5724 |
|
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|
5725 // We might have added oops to ClassLoaderData::_handles during the |
|
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|
5726 // concurrent marking phase. These oops point to newly allocated objects |
|
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|
5727 // that are guaranteed to be kept alive. Either by the direct allocation |
|
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|
5728 // code, or when the young collector processes the strong roots. Hence, |
|
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|
5729 // we don't have to revisit the _handles block during the remark phase. |
|
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|
5730 |
| 0 | 5731 verify_work_stacks_empty(); |
| 5732 // Restore evacuated mark words, if any, used for overflow list links | |
| 5733 if (!CMSOverflowEarlyRestoration) { | |
| 5734 restore_preserved_marks_if_any(); | |
| 5735 } | |
| 5736 verify_overflow_empty(); | |
| 5737 } | |
| 5738 | |
| 5739 //////////////////////////////////////////////////////// | |
| 5740 // Parallel Reference Processing Task Proxy Class | |
| 5741 //////////////////////////////////////////////////////// | |
|
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|
5742 class CMSRefProcTaskProxy: public AbstractGangTaskWOopQueues { |
| 0 | 5743 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; |
| 5744 CMSCollector* _collector; | |
| 5745 CMSBitMap* _mark_bit_map; | |
|
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|
5746 const MemRegion _span; |
| 0 | 5747 ProcessTask& _task; |
| 5748 | |
| 5749 public: | |
| 5750 CMSRefProcTaskProxy(ProcessTask& task, | |
| 5751 CMSCollector* collector, | |
| 5752 const MemRegion& span, | |
| 5753 CMSBitMap* mark_bit_map, | |
|
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|
5754 AbstractWorkGang* workers, |
| 0 | 5755 OopTaskQueueSet* task_queues): |
|
2369
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|
5756 // XXX Should superclass AGTWOQ also know about AWG since it knows |
|
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|
5757 // about the task_queues used by the AWG? Then it could initialize |
|
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|
5758 // the terminator() object. See 6984287. The set_for_termination() |
|
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|
5759 // below is a temporary band-aid for the regression in 6984287. |
|
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|
5760 AbstractGangTaskWOopQueues("Process referents by policy in parallel", |
|
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|
5761 task_queues), |
| 0 | 5762 _task(task), |
|
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|
5763 _collector(collector), _span(span), _mark_bit_map(mark_bit_map) |
|
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|
5764 { |
|
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|
5765 assert(_collector->_span.equals(_span) && !_span.is_empty(), |
|
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|
5766 "Inconsistency in _span"); |
|
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|
5767 set_for_termination(workers->active_workers()); |
|
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|
5768 } |
| 0 | 5769 |
|
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|
5770 OopTaskQueueSet* task_queues() { return queues(); } |
| 0 | 5771 |
| 5772 OopTaskQueue* work_queue(int i) { return task_queues()->queue(i); } | |
| 5773 | |
| 5774 void do_work_steal(int i, | |
| 5775 CMSParDrainMarkingStackClosure* drain, | |
| 5776 CMSParKeepAliveClosure* keep_alive, | |
| 5777 int* seed); | |
| 5778 | |
|
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|
5779 virtual void work(uint worker_id); |
| 0 | 5780 }; |
| 5781 | |
|
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|
5782 void CMSRefProcTaskProxy::work(uint worker_id) { |
|
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|
5783 assert(_collector->_span.equals(_span), "Inconsistency in _span"); |
| 0 | 5784 CMSParKeepAliveClosure par_keep_alive(_collector, _span, |
| 935 | 5785 _mark_bit_map, |
|
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changeset
|
5786 work_queue(worker_id)); |
| 0 | 5787 CMSParDrainMarkingStackClosure par_drain_stack(_collector, _span, |
| 935 | 5788 _mark_bit_map, |
|
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|
5789 work_queue(worker_id)); |
|
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|
5790 CMSIsAliveClosure is_alive_closure(_span, _mark_bit_map); |
|
4728
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|
5791 _task.work(worker_id, is_alive_closure, par_keep_alive, par_drain_stack); |
| 0 | 5792 if (_task.marks_oops_alive()) { |
|
4728
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|
5793 do_work_steal(worker_id, &par_drain_stack, &par_keep_alive, |
|
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|
5794 _collector->hash_seed(worker_id)); |
|
441e946dc1af
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|
5795 } |
|
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|
5796 assert(work_queue(worker_id)->size() == 0, "work_queue should be empty"); |
| 0 | 5797 assert(_collector->_overflow_list == NULL, "non-empty _overflow_list"); |
| 5798 } | |
| 5799 | |
| 5800 class CMSRefEnqueueTaskProxy: public AbstractGangTask { | |
| 5801 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; | |
| 5802 EnqueueTask& _task; | |
| 5803 | |
| 5804 public: | |
| 5805 CMSRefEnqueueTaskProxy(EnqueueTask& task) | |
| 5806 : AbstractGangTask("Enqueue reference objects in parallel"), | |
| 5807 _task(task) | |
| 5808 { } | |
| 5809 | |
|
4728
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|
5810 virtual void work(uint worker_id) |
| 0 | 5811 { |
|
4728
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changeset
|
5812 _task.work(worker_id); |
| 0 | 5813 } |
| 5814 }; | |
| 5815 | |
| 5816 CMSParKeepAliveClosure::CMSParKeepAliveClosure(CMSCollector* collector, | |
|
6725
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|
5817 MemRegion span, CMSBitMap* bit_map, OopTaskQueue* work_queue): |
| 0 | 5818 _span(span), |
| 5819 _bit_map(bit_map), | |
| 5820 _work_queue(work_queue), | |
|
6725
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|
5821 _mark_and_push(collector, span, bit_map, work_queue), |
| 0 | 5822 _low_water_mark(MIN2((uint)(work_queue->max_elems()/4), |
| 5823 (uint)(CMSWorkQueueDrainThreshold * ParallelGCThreads))) | |
| 5824 { } | |
| 5825 | |
| 5826 // . see if we can share work_queues with ParNew? XXX | |
| 5827 void CMSRefProcTaskProxy::do_work_steal(int i, | |
| 5828 CMSParDrainMarkingStackClosure* drain, | |
| 5829 CMSParKeepAliveClosure* keep_alive, | |
| 5830 int* seed) { | |
| 5831 OopTaskQueue* work_q = work_queue(i); | |
| 5832 NOT_PRODUCT(int num_steals = 0;) | |
| 5833 oop obj_to_scan; | |
| 5834 | |
| 5835 while (true) { | |
| 5836 // Completely finish any left over work from (an) earlier round(s) | |
| 5837 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
|
5838 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
|
5839 (size_t)ParGCDesiredObjsFromOverflowList); |
| 0 | 5840 // Now check if there's any work in the overflow list |
|
1833
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6984287: Regularize how GC parallel workers are specified.
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changeset
|
5841 // Passing ParallelGCThreads as the third parameter, no_of_gc_threads, |
|
8b10f48633dc
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diff
changeset
|
5842 // only affects the number of attempts made to get work from the |
|
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diff
changeset
|
5843 // overflow list and does not affect the number of workers. Just |
|
8b10f48633dc
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jmasa
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diff
changeset
|
5844 // pass ParallelGCThreads so this behavior is unchanged. |
| 0 | 5845 if (_collector->par_take_from_overflow_list(num_from_overflow_list, |
|
1833
8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
jmasa
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1777
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changeset
|
5846 work_q, |
|
8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
jmasa
parents:
1777
diff
changeset
|
5847 ParallelGCThreads)) { |
| 0 | 5848 // Found something in global overflow list; |
| 5849 // not yet ready to go stealing work from others. | |
| 5850 // We'd like to assert(work_q->size() != 0, ...) | |
| 5851 // because we just took work from the overflow list, | |
| 5852 // but of course we can't, since all of that might have | |
| 5853 // been already stolen from us. | |
| 5854 continue; | |
| 5855 } | |
| 5856 // Verify that we have no work before we resort to stealing | |
| 5857 assert(work_q->size() == 0, "Have work, shouldn't steal"); | |
| 5858 // Try to steal from other queues that have work | |
| 5859 if (task_queues()->steal(i, seed, /* reference */ obj_to_scan)) { | |
| 5860 NOT_PRODUCT(num_steals++;) | |
| 5861 assert(obj_to_scan->is_oop(), "Oops, not an oop!"); | |
| 5862 assert(_mark_bit_map->isMarked((HeapWord*)obj_to_scan), "Stole an unmarked oop?"); | |
| 5863 // Do scanning work | |
| 5864 obj_to_scan->oop_iterate(keep_alive); | |
| 5865 // Loop around, finish this work, and try to steal some more | |
| 5866 } else if (terminator()->offer_termination()) { | |
| 5867 break; // nirvana from the infinite cycle | |
| 5868 } | |
| 5869 } | |
| 5870 NOT_PRODUCT( | |
| 5871 if (PrintCMSStatistics != 0) { | |
| 5872 gclog_or_tty->print("\n\t(%d: stole %d oops)", i, num_steals); | |
| 5873 } | |
| 5874 ) | |
| 5875 } | |
| 5876 | |
| 5877 void CMSRefProcTaskExecutor::execute(ProcessTask& task) | |
| 5878 { | |
| 5879 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
|
1833
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diff
changeset
|
5880 FlexibleWorkGang* workers = gch->workers(); |
| 0 | 5881 assert(workers != NULL, "Need parallel worker threads."); |
| 5882 CMSRefProcTaskProxy rp_task(task, &_collector, | |
| 5883 _collector.ref_processor()->span(), | |
| 5884 _collector.markBitMap(), | |
|
1833
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jmasa
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diff
changeset
|
5885 workers, _collector.task_queues()); |
| 0 | 5886 workers->run_task(&rp_task); |
| 5887 } | |
| 5888 | |
| 5889 void CMSRefProcTaskExecutor::execute(EnqueueTask& task) | |
| 5890 { | |
| 5891 | |
| 5892 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
|
1833
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jmasa
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diff
changeset
|
5893 FlexibleWorkGang* workers = gch->workers(); |
| 0 | 5894 assert(workers != NULL, "Need parallel worker threads."); |
| 5895 CMSRefEnqueueTaskProxy enq_task(task); | |
| 5896 workers->run_task(&enq_task); | |
| 5897 } | |
| 5898 | |
| 5899 void CMSCollector::refProcessingWork(bool asynch, bool clear_all_soft_refs) { | |
| 5900 | |
| 5901 ResourceMark rm; | |
| 5902 HandleMark hm; | |
| 5903 | |
| 5904 ReferenceProcessor* rp = ref_processor(); | |
| 5905 assert(rp->span().equals(_span), "Spans should be equal"); | |
|
453
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|
5906 assert(!rp->enqueuing_is_done(), "Enqueuing should not be complete"); |
|
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changeset
|
5907 // Process weak references. |
|
457
27a80744a83b
6778647: snap(), snap_policy() should be renamed setup(), setup_policy()
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453
diff
changeset
|
5908 rp->setup_policy(clear_all_soft_refs); |
|
453
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diff
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|
5909 verify_work_stacks_empty(); |
|
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|
5910 |
| 0 | 5911 CMSKeepAliveClosure cmsKeepAliveClosure(this, _span, &_markBitMap, |
|
6725
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|
5912 &_markStack, false /* !preclean */); |
| 0 | 5913 CMSDrainMarkingStackClosure cmsDrainMarkingStackClosure(this, |
| 5914 _span, &_markBitMap, &_markStack, | |
|
452
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
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360
diff
changeset
|
5915 &cmsKeepAliveClosure, false /* !preclean */); |
| 0 | 5916 { |
| 5917 TraceTime t("weak refs processing", PrintGCDetails, false, gclog_or_tty); | |
| 5918 if (rp->processing_is_mt()) { | |
|
1833
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|
5919 // Set the degree of MT here. If the discovery is done MT, there |
|
8b10f48633dc
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changeset
|
5920 // may have been a different number of threads doing the discovery |
|
8b10f48633dc
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jmasa
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changeset
|
5921 // and a different number of discovered lists may have Ref objects. |
|
8b10f48633dc
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jmasa
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diff
changeset
|
5922 // That is OK as long as the Reference lists are balanced (see |
|
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changeset
|
5923 // balance_all_queues() and balance_queues()). |
|
4095
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
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diff
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|
5924 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
|
bca17e38de00
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jmasa
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3979
diff
changeset
|
5925 int active_workers = ParallelGCThreads; |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
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3979
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|
5926 FlexibleWorkGang* workers = gch->workers(); |
|
bca17e38de00
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changeset
|
5927 if (workers != NULL) { |
|
bca17e38de00
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3979
diff
changeset
|
5928 active_workers = workers->active_workers(); |
|
bca17e38de00
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3979
diff
changeset
|
5929 // The expectation is that active_workers will have already |
|
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
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3979
diff
changeset
|
5930 // been set to a reasonable value. If it has not been set, |
|
bca17e38de00
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3979
diff
changeset
|
5931 // investigate. |
|
bca17e38de00
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jmasa
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3979
diff
changeset
|
5932 assert(active_workers > 0, "Should have been set during scavenge"); |
|
bca17e38de00
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jmasa
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3979
diff
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|
5933 } |
|
bca17e38de00
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3979
diff
changeset
|
5934 rp->set_active_mt_degree(active_workers); |
| 0 | 5935 CMSRefProcTaskExecutor task_executor(*this); |
|
453
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diff
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|
5936 rp->process_discovered_references(&_is_alive_closure, |
| 0 | 5937 &cmsKeepAliveClosure, |
| 5938 &cmsDrainMarkingStackClosure, | |
| 5939 &task_executor); | |
| 5940 } else { | |
|
453
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452
diff
changeset
|
5941 rp->process_discovered_references(&_is_alive_closure, |
| 0 | 5942 &cmsKeepAliveClosure, |
| 5943 &cmsDrainMarkingStackClosure, | |
| 5944 NULL); | |
| 5945 } | |
| 5946 verify_work_stacks_empty(); | |
| 5947 } | |
| 5948 | |
|
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|
5949 if (should_unload_classes()) { |
| 0 | 5950 { |
| 5951 TraceTime t("class unloading", PrintGCDetails, false, gclog_or_tty); | |
| 5952 | |
| 5953 // Follow SystemDictionary roots and unload classes | |
| 5954 bool purged_class = SystemDictionary::do_unloading(&_is_alive_closure); | |
| 5955 | |
| 5956 // Follow CodeCache roots and unload any methods marked for unloading | |
|
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|
5957 CodeCache::do_unloading(&_is_alive_closure, purged_class); |
| 0 | 5958 |
| 5959 cmsDrainMarkingStackClosure.do_void(); | |
| 5960 verify_work_stacks_empty(); | |
| 5961 | |
| 5962 // Update subklass/sibling/implementor links in KlassKlass descendants | |
|
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5963 Klass::clean_weak_klass_links(&_is_alive_closure); |
|
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5964 // Nothing should have been pushed onto the working stacks. |
| 0 | 5965 verify_work_stacks_empty(); |
| 5966 } | |
| 5967 | |
| 5968 { | |
|
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5969 TraceTime t("scrub symbol table", PrintGCDetails, false, gclog_or_tty); |
|
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5970 // Clean up unreferenced symbols in symbol table. |
|
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|
5971 SymbolTable::unlink(); |
| 0 | 5972 } |
| 5973 } | |
| 5974 | |
|
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5975 // CMS doesn't use the StringTable as hard roots when class unloading is turned off. |
|
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5976 // Need to check if we really scanned the StringTable. |
|
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5977 if ((roots_scanning_options() & SharedHeap::SO_Strings) == 0) { |
|
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|
5978 TraceTime t("scrub string table", PrintGCDetails, false, gclog_or_tty); |
|
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5979 // Now clean up stale oops in StringTable |
|
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5980 StringTable::unlink(&_is_alive_closure); |
|
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|
5981 } |
|
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5982 |
| 0 | 5983 verify_work_stacks_empty(); |
| 5984 // Restore any preserved marks as a result of mark stack or | |
| 5985 // work queue overflow | |
| 5986 restore_preserved_marks_if_any(); // done single-threaded for now | |
| 5987 | |
| 5988 rp->set_enqueuing_is_done(true); | |
| 5989 if (rp->processing_is_mt()) { | |
|
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|
5990 rp->balance_all_queues(); |
| 0 | 5991 CMSRefProcTaskExecutor task_executor(*this); |
| 5992 rp->enqueue_discovered_references(&task_executor); | |
| 5993 } else { | |
| 5994 rp->enqueue_discovered_references(NULL); | |
| 5995 } | |
| 5996 rp->verify_no_references_recorded(); | |
| 5997 assert(!rp->discovery_enabled(), "should have been disabled"); | |
| 5998 } | |
| 5999 | |
| 6000 #ifndef PRODUCT | |
| 6001 void CMSCollector::check_correct_thread_executing() { | |
| 6002 Thread* t = Thread::current(); | |
| 6003 // Only the VM thread or the CMS thread should be here. | |
| 6004 assert(t->is_ConcurrentGC_thread() || t->is_VM_thread(), | |
| 6005 "Unexpected thread type"); | |
| 6006 // If this is the vm thread, the foreground process | |
| 6007 // should not be waiting. Note that _foregroundGCIsActive is | |
| 6008 // true while the foreground collector is waiting. | |
| 6009 if (_foregroundGCShouldWait) { | |
| 6010 // We cannot be the VM thread | |
| 6011 assert(t->is_ConcurrentGC_thread(), | |
| 6012 "Should be CMS thread"); | |
| 6013 } else { | |
| 6014 // We can be the CMS thread only if we are in a stop-world | |
| 6015 // phase of CMS collection. | |
| 6016 if (t->is_ConcurrentGC_thread()) { | |
| 6017 assert(_collectorState == InitialMarking || | |
| 6018 _collectorState == FinalMarking, | |
| 6019 "Should be a stop-world phase"); | |
| 6020 // The CMS thread should be holding the CMS_token. | |
| 6021 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 6022 "Potential interference with concurrently " | |
| 6023 "executing VM thread"); | |
| 6024 } | |
| 6025 } | |
| 6026 } | |
| 6027 #endif | |
| 6028 | |
| 6029 void CMSCollector::sweep(bool asynch) { | |
| 6030 assert(_collectorState == Sweeping, "just checking"); | |
| 6031 check_correct_thread_executing(); | |
| 6032 verify_work_stacks_empty(); | |
| 6033 verify_overflow_empty(); | |
|
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6034 increment_sweep_count(); |
|
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6035 TraceCMSMemoryManagerStats tms(_collectorState,GenCollectedHeap::heap()->gc_cause()); |
|
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6036 |
|
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|
6037 _inter_sweep_timer.stop(); |
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|
6038 _inter_sweep_estimate.sample(_inter_sweep_timer.seconds()); |
| 0 | 6039 size_policy()->avg_cms_free_at_sweep()->sample(_cmsGen->free()); |
| 6040 | |
|
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|
6041 assert(!_intra_sweep_timer.is_active(), "Should not be active"); |
|
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|
6042 _intra_sweep_timer.reset(); |
|
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|
6043 _intra_sweep_timer.start(); |
| 0 | 6044 if (asynch) { |
| 6045 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
| 6046 CMSPhaseAccounting pa(this, "sweep", !PrintGCDetails); | |
|
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|
6047 // First sweep the old gen |
| 0 | 6048 { |
| 6049 CMSTokenSyncWithLocks ts(true, _cmsGen->freelistLock(), | |
| 6050 bitMapLock()); | |
| 6051 sweepWork(_cmsGen, asynch); | |
| 6052 } | |
| 6053 | |
| 6054 // Update Universe::_heap_*_at_gc figures. | |
| 6055 // We need all the free list locks to make the abstract state | |
| 6056 // transition from Sweeping to Resetting. See detailed note | |
| 6057 // further below. | |
| 6058 { | |
|
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6059 CMSTokenSyncWithLocks ts(true, _cmsGen->freelistLock()); |
| 0 | 6060 // Update heap occupancy information which is used as |
| 6061 // input to soft ref clearing policy at the next gc. | |
| 6062 Universe::update_heap_info_at_gc(); | |
| 6063 _collectorState = Resizing; | |
| 6064 } | |
| 6065 } else { | |
| 6066 // already have needed locks | |
| 6067 sweepWork(_cmsGen, asynch); | |
| 6068 // Update heap occupancy information which is used as | |
| 6069 // input to soft ref clearing policy at the next gc. | |
| 6070 Universe::update_heap_info_at_gc(); | |
| 6071 _collectorState = Resizing; | |
| 6072 } | |
| 6073 verify_work_stacks_empty(); | |
| 6074 verify_overflow_empty(); | |
| 6075 | |
|
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|
6076 _intra_sweep_timer.stop(); |
|
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|
6077 _intra_sweep_estimate.sample(_intra_sweep_timer.seconds()); |
|
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6078 |
|
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|
6079 _inter_sweep_timer.reset(); |
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|
6080 _inter_sweep_timer.start(); |
| 0 | 6081 |
| 4911 | 6082 // We need to use a monotonically non-deccreasing time in ms |
| 6083 // or we will see time-warp warnings and os::javaTimeMillis() | |
| 6084 // does not guarantee monotonicity. | |
| 6085 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; | |
| 6086 update_time_of_last_gc(now); | |
| 0 | 6087 |
| 6088 // NOTE on abstract state transitions: | |
| 6089 // Mutators allocate-live and/or mark the mod-union table dirty | |
| 6090 // based on the state of the collection. The former is done in | |
| 6091 // the interval [Marking, Sweeping] and the latter in the interval | |
| 6092 // [Marking, Sweeping). Thus the transitions into the Marking state | |
| 6093 // and out of the Sweeping state must be synchronously visible | |
| 6094 // globally to the mutators. | |
| 6095 // The transition into the Marking state happens with the world | |
| 6096 // stopped so the mutators will globally see it. Sweeping is | |
| 6097 // done asynchronously by the background collector so the transition | |
| 6098 // from the Sweeping state to the Resizing state must be done | |
| 6099 // under the freelistLock (as is the check for whether to | |
| 6100 // allocate-live and whether to dirty the mod-union table). | |
| 6101 assert(_collectorState == Resizing, "Change of collector state to" | |
| 6102 " Resizing must be done under the freelistLocks (plural)"); | |
| 6103 | |
|
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|
6104 // Now that sweeping has been completed, we clear |
|
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|
6105 // the incremental_collection_failed flag, |
| 0 | 6106 // thus inviting a younger gen collection to promote into |
| 6107 // this generation. If such a promotion may still fail, | |
| 6108 // the flag will be set again when a young collection is | |
| 6109 // attempted. | |
| 6110 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
|
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|
6111 gch->clear_incremental_collection_failed(); // Worth retrying as fresh space may have been freed up |
| 0 | 6112 gch->update_full_collections_completed(_collection_count_start); |
| 6113 } | |
| 6114 | |
| 6115 // FIX ME!!! Looks like this belongs in CFLSpace, with | |
| 6116 // CMSGen merely delegating to it. | |
| 6117 void ConcurrentMarkSweepGeneration::setNearLargestChunk() { | |
|
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|
6118 double nearLargestPercent = FLSLargestBlockCoalesceProximity; |
| 0 | 6119 HeapWord* minAddr = _cmsSpace->bottom(); |
| 6120 HeapWord* largestAddr = | |
|
6028
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|
6121 (HeapWord*) _cmsSpace->dictionary()->find_largest_dict(); |
|
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|
6122 if (largestAddr == NULL) { |
| 0 | 6123 // The dictionary appears to be empty. In this case |
| 6124 // try to coalesce at the end of the heap. | |
| 6125 largestAddr = _cmsSpace->end(); | |
| 6126 } | |
| 6127 size_t largestOffset = pointer_delta(largestAddr, minAddr); | |
| 6128 size_t nearLargestOffset = | |
| 6129 (size_t)((double)largestOffset * nearLargestPercent) - MinChunkSize; | |
|
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|
6130 if (PrintFLSStatistics != 0) { |
|
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|
6131 gclog_or_tty->print_cr( |
|
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|
6132 "CMS: Large Block: " PTR_FORMAT ";" |
|
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|
6133 " Proximity: " PTR_FORMAT " -> " PTR_FORMAT, |
|
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|
6134 largestAddr, |
|
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|
6135 _cmsSpace->nearLargestChunk(), minAddr + nearLargestOffset); |
|
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|
6136 } |
| 0 | 6137 _cmsSpace->set_nearLargestChunk(minAddr + nearLargestOffset); |
| 6138 } | |
| 6139 | |
| 6140 bool ConcurrentMarkSweepGeneration::isNearLargestChunk(HeapWord* addr) { | |
| 6141 return addr >= _cmsSpace->nearLargestChunk(); | |
| 6142 } | |
| 6143 | |
| 6144 FreeChunk* ConcurrentMarkSweepGeneration::find_chunk_at_end() { | |
| 6145 return _cmsSpace->find_chunk_at_end(); | |
| 6146 } | |
| 6147 | |
| 6148 void ConcurrentMarkSweepGeneration::update_gc_stats(int current_level, | |
| 6149 bool full) { | |
| 6150 // The next lower level has been collected. Gather any statistics | |
| 6151 // that are of interest at this point. | |
| 6152 if (!full && (current_level + 1) == level()) { | |
| 6153 // Gather statistics on the young generation collection. | |
| 6154 collector()->stats().record_gc0_end(used()); | |
| 6155 } | |
| 6156 } | |
| 6157 | |
| 6158 CMSAdaptiveSizePolicy* ConcurrentMarkSweepGeneration::size_policy() { | |
| 6159 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 6160 assert(gch->kind() == CollectedHeap::GenCollectedHeap, | |
| 6161 "Wrong type of heap"); | |
| 6162 CMSAdaptiveSizePolicy* sp = (CMSAdaptiveSizePolicy*) | |
| 6163 gch->gen_policy()->size_policy(); | |
| 6164 assert(sp->is_gc_cms_adaptive_size_policy(), | |
| 6165 "Wrong type of size policy"); | |
| 6166 return sp; | |
| 6167 } | |
| 6168 | |
| 6169 void ConcurrentMarkSweepGeneration::rotate_debug_collection_type() { | |
| 6170 if (PrintGCDetails && Verbose) { | |
| 6171 gclog_or_tty->print("Rotate from %d ", _debug_collection_type); | |
| 6172 } | |
| 6173 _debug_collection_type = (CollectionTypes) (_debug_collection_type + 1); | |
| 6174 _debug_collection_type = | |
| 6175 (CollectionTypes) (_debug_collection_type % Unknown_collection_type); | |
| 6176 if (PrintGCDetails && Verbose) { | |
| 6177 gclog_or_tty->print_cr("to %d ", _debug_collection_type); | |
| 6178 } | |
| 6179 } | |
| 6180 | |
| 6181 void CMSCollector::sweepWork(ConcurrentMarkSweepGeneration* gen, | |
| 6182 bool asynch) { | |
| 6183 // We iterate over the space(s) underlying this generation, | |
| 6184 // checking the mark bit map to see if the bits corresponding | |
| 6185 // to specific blocks are marked or not. Blocks that are | |
| 6186 // marked are live and are not swept up. All remaining blocks | |
| 6187 // are swept up, with coalescing on-the-fly as we sweep up | |
| 6188 // contiguous free and/or garbage blocks: | |
| 6189 // We need to ensure that the sweeper synchronizes with allocators | |
| 6190 // and stop-the-world collectors. In particular, the following | |
| 6191 // locks are used: | |
| 6192 // . CMS token: if this is held, a stop the world collection cannot occur | |
| 6193 // . freelistLock: if this is held no allocation can occur from this | |
| 6194 // generation by another thread | |
| 6195 // . bitMapLock: if this is held, no other thread can access or update | |
| 6196 // | |
| 6197 | |
| 6198 // Note that we need to hold the freelistLock if we use | |
| 6199 // block iterate below; else the iterator might go awry if | |
| 6200 // a mutator (or promotion) causes block contents to change | |
| 6201 // (for instance if the allocator divvies up a block). | |
| 6202 // If we hold the free list lock, for all practical purposes | |
| 6203 // young generation GC's can't occur (they'll usually need to | |
| 6204 // promote), so we might as well prevent all young generation | |
| 6205 // GC's while we do a sweeping step. For the same reason, we might | |
| 6206 // as well take the bit map lock for the entire duration | |
| 6207 | |
| 6208 // check that we hold the requisite locks | |
| 6209 assert(have_cms_token(), "Should hold cms token"); | |
| 6210 assert( (asynch && ConcurrentMarkSweepThread::cms_thread_has_cms_token()) | |
| 6211 || (!asynch && ConcurrentMarkSweepThread::vm_thread_has_cms_token()), | |
| 6212 "Should possess CMS token to sweep"); | |
| 6213 assert_lock_strong(gen->freelistLock()); | |
| 6214 assert_lock_strong(bitMapLock()); | |
| 6215 | |
|
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6216 assert(!_inter_sweep_timer.is_active(), "Was switched off in an outer context"); |
|
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6217 assert(_intra_sweep_timer.is_active(), "Was switched on in an outer context"); |
|
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6218 gen->cmsSpace()->beginSweepFLCensus((float)(_inter_sweep_timer.seconds()), |
|
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6219 _inter_sweep_estimate.padded_average(), |
|
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6220 _intra_sweep_estimate.padded_average()); |
| 0 | 6221 gen->setNearLargestChunk(); |
| 6222 | |
| 6223 { | |
| 6224 SweepClosure sweepClosure(this, gen, &_markBitMap, | |
| 6225 CMSYield && asynch); | |
| 6226 gen->cmsSpace()->blk_iterate_careful(&sweepClosure); | |
| 6227 // We need to free-up/coalesce garbage/blocks from a | |
| 6228 // co-terminal free run. This is done in the SweepClosure | |
| 6229 // destructor; so, do not remove this scope, else the | |
| 6230 // end-of-sweep-census below will be off by a little bit. | |
| 6231 } | |
| 6232 gen->cmsSpace()->sweep_completed(); | |
|
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6233 gen->cmsSpace()->endSweepFLCensus(sweep_count()); |
|
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6234 if (should_unload_classes()) { // unloaded classes this cycle, |
|
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6235 _concurrent_cycles_since_last_unload = 0; // ... reset count |
|
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6236 } else { // did not unload classes, |
|
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6237 _concurrent_cycles_since_last_unload++; // ... increment count |
|
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|
6238 } |
| 0 | 6239 } |
| 6240 | |
| 6241 // Reset CMS data structures (for now just the marking bit map) | |
| 6242 // preparatory for the next cycle. | |
| 6243 void CMSCollector::reset(bool asynch) { | |
| 6244 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 6245 CMSAdaptiveSizePolicy* sp = size_policy(); | |
| 6246 AdaptiveSizePolicyOutput(sp, gch->total_collections()); | |
| 6247 if (asynch) { | |
| 6248 CMSTokenSyncWithLocks ts(true, bitMapLock()); | |
| 6249 | |
| 6250 // If the state is not "Resetting", the foreground thread | |
| 6251 // has done a collection and the resetting. | |
| 6252 if (_collectorState != Resetting) { | |
| 6253 assert(_collectorState == Idling, "The state should only change" | |
| 6254 " because the foreground collector has finished the collection"); | |
| 6255 return; | |
| 6256 } | |
| 6257 | |
| 6258 // Clear the mark bitmap (no grey objects to start with) | |
| 6259 // for the next cycle. | |
| 6260 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
| 6261 CMSPhaseAccounting cmspa(this, "reset", !PrintGCDetails); | |
| 6262 | |
| 6263 HeapWord* curAddr = _markBitMap.startWord(); | |
| 6264 while (curAddr < _markBitMap.endWord()) { | |
| 6265 size_t remaining = pointer_delta(_markBitMap.endWord(), curAddr); | |
| 6266 MemRegion chunk(curAddr, MIN2(CMSBitMapYieldQuantum, remaining)); | |
| 6267 _markBitMap.clear_large_range(chunk); | |
| 6268 if (ConcurrentMarkSweepThread::should_yield() && | |
| 6269 !foregroundGCIsActive() && | |
| 6270 CMSYield) { | |
| 6271 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 6272 "CMS thread should hold CMS token"); | |
| 6273 assert_lock_strong(bitMapLock()); | |
| 6274 bitMapLock()->unlock(); | |
| 6275 ConcurrentMarkSweepThread::desynchronize(true); | |
| 6276 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 6277 stopTimer(); | |
| 6278 if (PrintCMSStatistics != 0) { | |
| 6279 incrementYields(); | |
| 6280 } | |
| 6281 icms_wait(); | |
| 6282 | |
| 6283 // See the comment in coordinator_yield() | |
| 6284 for (unsigned i = 0; i < CMSYieldSleepCount && | |
|
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|
6285 ConcurrentMarkSweepThread::should_yield() && |
|
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|
6286 !CMSCollector::foregroundGCIsActive(); ++i) { |
| 0 | 6287 os::sleep(Thread::current(), 1, false); |
| 6288 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 6289 } | |
| 6290 | |
| 6291 ConcurrentMarkSweepThread::synchronize(true); | |
| 6292 bitMapLock()->lock_without_safepoint_check(); | |
| 6293 startTimer(); | |
| 6294 } | |
| 6295 curAddr = chunk.end(); | |
| 6296 } | |
|
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diff
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|
6297 // A successful mostly concurrent collection has been done. |
|
0bfd3fb24150
6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
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1289
diff
changeset
|
6298 // 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.
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diff
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|
6299 // 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.
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diff
changeset
|
6300 // and count. |
|
0bfd3fb24150
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|
6301 sp->reset_gc_overhead_limit_count(); |
| 0 | 6302 _collectorState = Idling; |
| 6303 } else { | |
| 6304 // already have the lock | |
| 6305 assert(_collectorState == Resetting, "just checking"); | |
| 6306 assert_lock_strong(bitMapLock()); | |
| 6307 _markBitMap.clear_all(); | |
| 6308 _collectorState = Idling; | |
| 6309 } | |
| 6310 | |
| 6311 // Stop incremental mode after a cycle completes, so that any future cycles | |
| 6312 // are triggered by allocation. | |
| 6313 stop_icms(); | |
| 6314 | |
| 6315 NOT_PRODUCT( | |
| 6316 if (RotateCMSCollectionTypes) { | |
| 6317 _cmsGen->rotate_debug_collection_type(); | |
| 6318 } | |
| 6319 ) | |
| 6320 } | |
| 6321 | |
|
6064
9d679effd28c
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6028
diff
changeset
|
6322 void CMSCollector::do_CMS_operation(CMS_op_type op, GCCause::Cause gc_cause) { |
| 0 | 6323 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps); |
| 6324 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
|
6064
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diff
changeset
|
6325 TraceTime t(GCCauseString("GC", gc_cause), PrintGC, !PrintGCDetails, gclog_or_tty); |
| 0 | 6326 TraceCollectorStats tcs(counters()); |
| 6327 | |
| 6328 switch (op) { | |
| 6329 case CMS_op_checkpointRootsInitial: { | |
|
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diff
changeset
|
6330 SvcGCMarker sgcm(SvcGCMarker::OTHER); |
| 0 | 6331 checkpointRootsInitial(true); // asynch |
| 6332 if (PrintGC) { | |
| 6333 _cmsGen->printOccupancy("initial-mark"); | |
| 6334 } | |
| 6335 break; | |
| 6336 } | |
| 6337 case CMS_op_checkpointRootsFinal: { | |
|
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diff
changeset
|
6338 SvcGCMarker sgcm(SvcGCMarker::OTHER); |
| 0 | 6339 checkpointRootsFinal(true, // asynch |
| 6340 false, // !clear_all_soft_refs | |
| 6341 false); // !init_mark_was_synchronous | |
| 6342 if (PrintGC) { | |
| 6343 _cmsGen->printOccupancy("remark"); | |
| 6344 } | |
| 6345 break; | |
| 6346 } | |
| 6347 default: | |
| 6348 fatal("No such CMS_op"); | |
| 6349 } | |
| 6350 } | |
| 6351 | |
| 6352 #ifndef PRODUCT | |
| 6353 size_t const CMSCollector::skip_header_HeapWords() { | |
| 6354 return FreeChunk::header_size(); | |
| 6355 } | |
| 6356 | |
| 6357 // Try and collect here conditions that should hold when | |
| 6358 // CMS thread is exiting. The idea is that the foreground GC | |
| 6359 // thread should not be blocked if it wants to terminate | |
| 6360 // the CMS thread and yet continue to run the VM for a while | |
| 6361 // after that. | |
| 6362 void CMSCollector::verify_ok_to_terminate() const { | |
| 6363 assert(Thread::current()->is_ConcurrentGC_thread(), | |
| 6364 "should be called by CMS thread"); | |
| 6365 assert(!_foregroundGCShouldWait, "should be false"); | |
| 6366 // We could check here that all the various low-level locks | |
| 6367 // are not held by the CMS thread, but that is overkill; see | |
| 6368 // also CMSThread::verify_ok_to_terminate() where the CGC_lock | |
| 6369 // is checked. | |
| 6370 } | |
| 6371 #endif | |
| 6372 | |
| 6373 size_t CMSCollector::block_size_using_printezis_bits(HeapWord* addr) const { | |
|
453
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diff
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|
6374 assert(_markBitMap.isMarked(addr) && _markBitMap.isMarked(addr + 1), |
|
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diff
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|
6375 "missing Printezis mark?"); |
| 0 | 6376 HeapWord* nextOneAddr = _markBitMap.getNextMarkedWordAddress(addr + 2); |
| 6377 size_t size = pointer_delta(nextOneAddr + 1, addr); | |
| 6378 assert(size == CompactibleFreeListSpace::adjustObjectSize(size), | |
| 6379 "alignment problem"); | |
| 6380 assert(size >= 3, "Necessary for Printezis marks to work"); | |
| 6381 return size; | |
| 6382 } | |
| 6383 | |
| 6384 // A variant of the above (block_size_using_printezis_bits()) except | |
| 6385 // that we return 0 if the P-bits are not yet set. | |
| 6386 size_t CMSCollector::block_size_if_printezis_bits(HeapWord* addr) const { | |
|
2226
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2177
diff
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|
6387 if (_markBitMap.isMarked(addr + 1)) { |
|
c5a923563727
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diff
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|
6388 assert(_markBitMap.isMarked(addr), "P-bit can be set only for marked objects"); |
| 0 | 6389 HeapWord* nextOneAddr = _markBitMap.getNextMarkedWordAddress(addr + 2); |
| 6390 size_t size = pointer_delta(nextOneAddr + 1, addr); | |
| 6391 assert(size == CompactibleFreeListSpace::adjustObjectSize(size), | |
| 6392 "alignment problem"); | |
| 6393 assert(size >= 3, "Necessary for Printezis marks to work"); | |
| 6394 return size; | |
|
2226
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2177
diff
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|
6395 } |
|
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2177
diff
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|
6396 return 0; |
| 0 | 6397 } |
| 6398 | |
| 6399 HeapWord* CMSCollector::next_card_start_after_block(HeapWord* addr) const { | |
| 6400 size_t sz = 0; | |
| 6401 oop p = (oop)addr; | |
|
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diff
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|
6402 if (p->klass_or_null() != NULL) { |
| 0 | 6403 sz = CompactibleFreeListSpace::adjustObjectSize(p->size()); |
| 6404 } else { | |
| 6405 sz = block_size_using_printezis_bits(addr); | |
| 6406 } | |
| 6407 assert(sz > 0, "size must be nonzero"); | |
| 6408 HeapWord* next_block = addr + sz; | |
| 6409 HeapWord* next_card = (HeapWord*)round_to((uintptr_t)next_block, | |
| 6410 CardTableModRefBS::card_size); | |
| 6411 assert(round_down((uintptr_t)addr, CardTableModRefBS::card_size) < | |
| 6412 round_down((uintptr_t)next_card, CardTableModRefBS::card_size), | |
| 6413 "must be different cards"); | |
| 6414 return next_card; | |
| 6415 } | |
| 6416 | |
| 6417 | |
| 6418 // CMS Bit Map Wrapper ///////////////////////////////////////// | |
| 6419 | |
| 6420 // Construct a CMS bit map infrastructure, but don't create the | |
| 6421 // bit vector itself. That is done by a separate call CMSBitMap::allocate() | |
| 6422 // further below. | |
| 6423 CMSBitMap::CMSBitMap(int shifter, int mutex_rank, const char* mutex_name): | |
|
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|
6424 _bm(), |
| 0 | 6425 _shifter(shifter), |
| 6426 _lock(mutex_rank >= 0 ? new Mutex(mutex_rank, mutex_name, true) : NULL) | |
| 6427 { | |
| 6428 _bmStartWord = 0; | |
| 6429 _bmWordSize = 0; | |
| 6430 } | |
| 6431 | |
| 6432 bool CMSBitMap::allocate(MemRegion mr) { | |
| 6433 _bmStartWord = mr.start(); | |
| 6434 _bmWordSize = mr.word_size(); | |
| 6435 ReservedSpace brs(ReservedSpace::allocation_align_size_up( | |
| 6436 (_bmWordSize >> (_shifter + LogBitsPerByte)) + 1)); | |
| 6437 if (!brs.is_reserved()) { | |
| 6438 warning("CMS bit map allocation failure"); | |
| 6439 return false; | |
| 6440 } | |
| 6441 // For now we'll just commit all of the bit map up fromt. | |
| 6442 // Later on we'll try to be more parsimonious with swap. | |
| 6443 if (!_virtual_space.initialize(brs, brs.size())) { | |
| 6444 warning("CMS bit map backing store failure"); | |
| 6445 return false; | |
| 6446 } | |
| 6447 assert(_virtual_space.committed_size() == brs.size(), | |
| 6448 "didn't reserve backing store for all of CMS bit map?"); | |
|
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|
6449 _bm.set_map((BitMap::bm_word_t*)_virtual_space.low()); |
| 0 | 6450 assert(_virtual_space.committed_size() << (_shifter + LogBitsPerByte) >= |
| 6451 _bmWordSize, "inconsistency in bit map sizing"); | |
| 6452 _bm.set_size(_bmWordSize >> _shifter); | |
| 6453 | |
| 6454 // bm.clear(); // can we rely on getting zero'd memory? verify below | |
| 6455 assert(isAllClear(), | |
| 6456 "Expected zero'd memory from ReservedSpace constructor"); | |
| 6457 assert(_bm.size() == heapWordDiffToOffsetDiff(sizeInWords()), | |
| 6458 "consistency check"); | |
| 6459 return true; | |
| 6460 } | |
| 6461 | |
| 6462 void CMSBitMap::dirty_range_iterate_clear(MemRegion mr, MemRegionClosure* cl) { | |
| 6463 HeapWord *next_addr, *end_addr, *last_addr; | |
| 6464 assert_locked(); | |
| 6465 assert(covers(mr), "out-of-range error"); | |
| 6466 // XXX assert that start and end are appropriately aligned | |
| 6467 for (next_addr = mr.start(), end_addr = mr.end(); | |
| 6468 next_addr < end_addr; next_addr = last_addr) { | |
| 6469 MemRegion dirty_region = getAndClearMarkedRegion(next_addr, end_addr); | |
| 6470 last_addr = dirty_region.end(); | |
| 6471 if (!dirty_region.is_empty()) { | |
| 6472 cl->do_MemRegion(dirty_region); | |
| 6473 } else { | |
| 6474 assert(last_addr == end_addr, "program logic"); | |
| 6475 return; | |
| 6476 } | |
| 6477 } | |
| 6478 } | |
| 6479 | |
| 6480 #ifndef PRODUCT | |
| 6481 void CMSBitMap::assert_locked() const { | |
| 6482 CMSLockVerifier::assert_locked(lock()); | |
| 6483 } | |
| 6484 | |
| 6485 bool CMSBitMap::covers(MemRegion mr) const { | |
| 6486 // assert(_bm.map() == _virtual_space.low(), "map inconsistency"); | |
| 6487 assert((size_t)_bm.size() == (_bmWordSize >> _shifter), | |
| 6488 "size inconsistency"); | |
| 6489 return (mr.start() >= _bmStartWord) && | |
| 6490 (mr.end() <= endWord()); | |
| 6491 } | |
| 6492 | |
| 6493 bool CMSBitMap::covers(HeapWord* start, size_t size) const { | |
| 6494 return (start >= _bmStartWord && (start + size) <= endWord()); | |
| 6495 } | |
| 6496 | |
| 6497 void CMSBitMap::verifyNoOneBitsInRange(HeapWord* left, HeapWord* right) { | |
| 6498 // verify that there are no 1 bits in the interval [left, right) | |
| 6499 FalseBitMapClosure falseBitMapClosure; | |
| 6500 iterate(&falseBitMapClosure, left, right); | |
| 6501 } | |
| 6502 | |
| 6503 void CMSBitMap::region_invariant(MemRegion mr) | |
| 6504 { | |
| 6505 assert_locked(); | |
| 6506 // mr = mr.intersection(MemRegion(_bmStartWord, _bmWordSize)); | |
| 6507 assert(!mr.is_empty(), "unexpected empty region"); | |
| 6508 assert(covers(mr), "mr should be covered by bit map"); | |
| 6509 // convert address range into offset range | |
| 6510 size_t start_ofs = heapWordToOffset(mr.start()); | |
| 6511 // Make sure that end() is appropriately aligned | |
| 6512 assert(mr.end() == (HeapWord*)round_to((intptr_t)mr.end(), | |
| 6513 (1 << (_shifter+LogHeapWordSize))), | |
| 6514 "Misaligned mr.end()"); | |
| 6515 size_t end_ofs = heapWordToOffset(mr.end()); | |
| 6516 assert(end_ofs > start_ofs, "Should mark at least one bit"); | |
| 6517 } | |
| 6518 | |
| 6519 #endif | |
| 6520 | |
| 6521 bool CMSMarkStack::allocate(size_t size) { | |
| 6522 // allocate a stack of the requisite depth | |
| 6523 ReservedSpace rs(ReservedSpace::allocation_align_size_up( | |
| 6524 size * sizeof(oop))); | |
| 6525 if (!rs.is_reserved()) { | |
| 6526 warning("CMSMarkStack allocation failure"); | |
| 6527 return false; | |
| 6528 } | |
| 6529 if (!_virtual_space.initialize(rs, rs.size())) { | |
| 6530 warning("CMSMarkStack backing store failure"); | |
| 6531 return false; | |
| 6532 } | |
| 6533 assert(_virtual_space.committed_size() == rs.size(), | |
| 6534 "didn't reserve backing store for all of CMS stack?"); | |
| 6535 _base = (oop*)(_virtual_space.low()); | |
| 6536 _index = 0; | |
| 6537 _capacity = size; | |
| 6538 NOT_PRODUCT(_max_depth = 0); | |
| 6539 return true; | |
| 6540 } | |
| 6541 | |
| 6542 // XXX FIX ME !!! In the MT case we come in here holding a | |
| 6543 // leaf lock. For printing we need to take a further lock | |
| 6544 // which has lower rank. We need to recallibrate the two | |
| 6545 // lock-ranks involved in order to be able to rpint the | |
| 6546 // messages below. (Or defer the printing to the caller. | |
| 6547 // For now we take the expedient path of just disabling the | |
| 6548 // messages for the problematic case.) | |
| 6549 void CMSMarkStack::expand() { | |
| 1284 | 6550 assert(_capacity <= MarkStackSizeMax, "stack bigger than permitted"); |
| 6551 if (_capacity == MarkStackSizeMax) { | |
| 0 | 6552 if (_hit_limit++ == 0 && !CMSConcurrentMTEnabled && PrintGCDetails) { |
| 6553 // We print a warning message only once per CMS cycle. | |
| 6554 gclog_or_tty->print_cr(" (benign) Hit CMSMarkStack max size limit"); | |
| 6555 } | |
| 6556 return; | |
| 6557 } | |
| 6558 // Double capacity if possible | |
| 1284 | 6559 size_t new_capacity = MIN2(_capacity*2, MarkStackSizeMax); |
| 0 | 6560 // Do not give up existing stack until we have managed to |
| 6561 // get the double capacity that we desired. | |
| 6562 ReservedSpace rs(ReservedSpace::allocation_align_size_up( | |
| 6563 new_capacity * sizeof(oop))); | |
| 6564 if (rs.is_reserved()) { | |
| 6565 // Release the backing store associated with old stack | |
| 6566 _virtual_space.release(); | |
| 6567 // Reinitialize virtual space for new stack | |
| 6568 if (!_virtual_space.initialize(rs, rs.size())) { | |
| 6569 fatal("Not enough swap for expanded marking stack"); | |
| 6570 } | |
| 6571 _base = (oop*)(_virtual_space.low()); | |
| 6572 _index = 0; | |
| 6573 _capacity = new_capacity; | |
| 6574 } else if (_failed_double++ == 0 && !CMSConcurrentMTEnabled && PrintGCDetails) { | |
| 6575 // Failed to double capacity, continue; | |
| 6576 // we print a detail message only once per CMS cycle. | |
| 6577 gclog_or_tty->print(" (benign) Failed to expand marking stack from "SIZE_FORMAT"K to " | |
| 6578 SIZE_FORMAT"K", | |
| 6579 _capacity / K, new_capacity / K); | |
| 6580 } | |
| 6581 } | |
| 6582 | |
| 6583 | |
| 6584 // Closures | |
| 6585 // XXX: there seems to be a lot of code duplication here; | |
| 6586 // should refactor and consolidate common code. | |
| 6587 | |
| 6588 // This closure is used to mark refs into the CMS generation in | |
| 6589 // the CMS bit map. Called at the first checkpoint. This closure | |
| 6590 // assumes that we do not need to re-mark dirty cards; if the CMS | |
|
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|
6591 // generation on which this is used is not an oldest |
| 0 | 6592 // generation then this will lose younger_gen cards! |
| 6593 | |
| 6594 MarkRefsIntoClosure::MarkRefsIntoClosure( | |
|
994
753cf9794df9
6885169: merge of 4957990 and 6863023 causes conflict on do_nmethods
jrose
parents:
993
diff
changeset
|
6595 MemRegion span, CMSBitMap* bitMap): |
| 0 | 6596 _span(span), |
|
994
753cf9794df9
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jrose
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993
diff
changeset
|
6597 _bitMap(bitMap) |
| 0 | 6598 { |
| 6599 assert(_ref_processor == NULL, "deliberately left NULL"); | |
| 6600 assert(_bitMap->covers(_span), "_bitMap/_span mismatch"); | |
| 6601 } | |
| 6602 | |
|
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94
diff
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|
6603 void MarkRefsIntoClosure::do_oop(oop obj) { |
| 0 | 6604 // if p points into _span, then mark corresponding bit in _markBitMap |
|
113
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94
diff
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|
6605 assert(obj->is_oop(), "expected an oop"); |
|
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
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94
diff
changeset
|
6606 HeapWord* addr = (HeapWord*)obj; |
|
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coleenp
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94
diff
changeset
|
6607 if (_span.contains(addr)) { |
|
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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
|
6608 // this should be made more efficient |
|
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
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94
diff
changeset
|
6609 _bitMap->mark(addr); |
|
ba764ed4b6f2
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coleenp
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94
diff
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|
6610 } |
|
ba764ed4b6f2
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94
diff
changeset
|
6611 } |
|
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
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94
diff
changeset
|
6612 |
|
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
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94
diff
changeset
|
6613 void MarkRefsIntoClosure::do_oop(oop* p) { MarkRefsIntoClosure::do_oop_work(p); } |
|
ba764ed4b6f2
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94
diff
changeset
|
6614 void MarkRefsIntoClosure::do_oop(narrowOop* p) { MarkRefsIntoClosure::do_oop_work(p); } |
| 0 | 6615 |
| 6616 // A variant of the above, used for CMS marking verification. | |
| 6617 MarkRefsIntoVerifyClosure::MarkRefsIntoVerifyClosure( | |
|
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6618 MemRegion span, CMSBitMap* verification_bm, CMSBitMap* cms_bm): |
| 0 | 6619 _span(span), |
| 6620 _verification_bm(verification_bm), | |
|
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6621 _cms_bm(cms_bm) |
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6622 { |
| 0 | 6623 assert(_ref_processor == NULL, "deliberately left NULL"); |
| 6624 assert(_verification_bm->covers(_span), "_verification_bm/_span mismatch"); | |
| 6625 } | |
| 6626 | |
|
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6627 void MarkRefsIntoVerifyClosure::do_oop(oop obj) { |
| 0 | 6628 // if p points into _span, then mark corresponding bit in _markBitMap |
|
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6629 assert(obj->is_oop(), "expected an oop"); |
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6630 HeapWord* addr = (HeapWord*)obj; |
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6631 if (_span.contains(addr)) { |
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6632 _verification_bm->mark(addr); |
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6633 if (!_cms_bm->isMarked(addr)) { |
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6634 oop(addr)->print(); |
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6635 gclog_or_tty->print_cr(" (" INTPTR_FORMAT " should have been marked)", addr); |
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6636 fatal("... aborting"); |
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6637 } |
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6638 } |
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6639 } |
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6640 |
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6641 void MarkRefsIntoVerifyClosure::do_oop(oop* p) { MarkRefsIntoVerifyClosure::do_oop_work(p); } |
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6642 void MarkRefsIntoVerifyClosure::do_oop(narrowOop* p) { MarkRefsIntoVerifyClosure::do_oop_work(p); } |
| 0 | 6643 |
| 6644 ////////////////////////////////////////////////// | |
| 6645 // MarkRefsIntoAndScanClosure | |
| 6646 ////////////////////////////////////////////////// | |
| 6647 | |
| 6648 MarkRefsIntoAndScanClosure::MarkRefsIntoAndScanClosure(MemRegion span, | |
| 6649 ReferenceProcessor* rp, | |
| 6650 CMSBitMap* bit_map, | |
| 6651 CMSBitMap* mod_union_table, | |
| 6652 CMSMarkStack* mark_stack, | |
| 6653 CMSCollector* collector, | |
| 6654 bool should_yield, | |
| 6655 bool concurrent_precleaning): | |
| 6656 _collector(collector), | |
| 6657 _span(span), | |
| 6658 _bit_map(bit_map), | |
| 6659 _mark_stack(mark_stack), | |
| 6660 _pushAndMarkClosure(collector, span, rp, bit_map, mod_union_table, | |
|
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6661 mark_stack, concurrent_precleaning), |
| 0 | 6662 _yield(should_yield), |
| 6663 _concurrent_precleaning(concurrent_precleaning), | |
| 6664 _freelistLock(NULL) | |
| 6665 { | |
| 6666 _ref_processor = rp; | |
| 6667 assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL"); | |
| 6668 } | |
| 6669 | |
| 6670 // This closure is used to mark refs into the CMS generation at the | |
| 6671 // second (final) checkpoint, and to scan and transitively follow | |
| 6672 // the unmarked oops. It is also used during the concurrent precleaning | |
| 6673 // phase while scanning objects on dirty cards in the CMS generation. | |
| 6674 // The marks are made in the marking bit map and the marking stack is | |
| 6675 // used for keeping the (newly) grey objects during the scan. | |
| 6676 // The parallel version (Par_...) appears further below. | |
|
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6677 void MarkRefsIntoAndScanClosure::do_oop(oop obj) { |
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6678 if (obj != NULL) { |
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6679 assert(obj->is_oop(), "expected an oop"); |
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6680 HeapWord* addr = (HeapWord*)obj; |
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6681 assert(_mark_stack->isEmpty(), "pre-condition (eager drainage)"); |
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6682 assert(_collector->overflow_list_is_empty(), |
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6683 "overflow list should be empty"); |
| 0 | 6684 if (_span.contains(addr) && |
| 6685 !_bit_map->isMarked(addr)) { | |
| 6686 // mark bit map (object is now grey) | |
| 6687 _bit_map->mark(addr); | |
| 6688 // push on marking stack (stack should be empty), and drain the | |
| 6689 // stack by applying this closure to the oops in the oops popped | |
| 6690 // from the stack (i.e. blacken the grey objects) | |
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6691 bool res = _mark_stack->push(obj); |
| 0 | 6692 assert(res, "Should have space to push on empty stack"); |
| 6693 do { | |
| 6694 oop new_oop = _mark_stack->pop(); | |
| 6695 assert(new_oop != NULL && new_oop->is_oop(), "Expected an oop"); | |
| 6696 assert(_bit_map->isMarked((HeapWord*)new_oop), | |
| 6697 "only grey objects on this stack"); | |
| 6698 // iterate over the oops in this oop, marking and pushing | |
| 6699 // the ones in CMS heap (i.e. in _span). | |
| 6700 new_oop->oop_iterate(&_pushAndMarkClosure); | |
| 6701 // check if it's time to yield | |
| 6702 do_yield_check(); | |
| 6703 } while (!_mark_stack->isEmpty() || | |
| 6704 (!_concurrent_precleaning && take_from_overflow_list())); | |
| 6705 // if marking stack is empty, and we are not doing this | |
| 6706 // during precleaning, then check the overflow list | |
| 6707 } | |
| 6708 assert(_mark_stack->isEmpty(), "post-condition (eager drainage)"); | |
| 6709 assert(_collector->overflow_list_is_empty(), | |
| 6710 "overflow list was drained above"); | |
| 6711 // We could restore evacuated mark words, if any, used for | |
| 6712 // overflow list links here because the overflow list is | |
| 6713 // provably empty here. That would reduce the maximum | |
| 6714 // size requirements for preserved_{oop,mark}_stack. | |
| 6715 // But we'll just postpone it until we are all done | |
| 6716 // so we can just stream through. | |
| 6717 if (!_concurrent_precleaning && CMSOverflowEarlyRestoration) { | |
| 6718 _collector->restore_preserved_marks_if_any(); | |
| 6719 assert(_collector->no_preserved_marks(), "No preserved marks"); | |
| 6720 } | |
| 6721 assert(!CMSOverflowEarlyRestoration || _collector->no_preserved_marks(), | |
| 6722 "All preserved marks should have been restored above"); | |
| 6723 } | |
| 6724 } | |
| 6725 | |
|
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6726 void MarkRefsIntoAndScanClosure::do_oop(oop* p) { MarkRefsIntoAndScanClosure::do_oop_work(p); } |
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6727 void MarkRefsIntoAndScanClosure::do_oop(narrowOop* p) { MarkRefsIntoAndScanClosure::do_oop_work(p); } |
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6728 |
| 0 | 6729 void MarkRefsIntoAndScanClosure::do_yield_work() { |
| 6730 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 6731 "CMS thread should hold CMS token"); | |
| 6732 assert_lock_strong(_freelistLock); | |
| 6733 assert_lock_strong(_bit_map->lock()); | |
| 6734 // relinquish the free_list_lock and bitMaplock() | |
| 6735 _bit_map->lock()->unlock(); | |
| 6736 _freelistLock->unlock(); | |
| 6737 ConcurrentMarkSweepThread::desynchronize(true); | |
| 6738 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 6739 _collector->stopTimer(); | |
| 6740 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 6741 if (PrintCMSStatistics != 0) { | |
| 6742 _collector->incrementYields(); | |
| 6743 } | |
| 6744 _collector->icms_wait(); | |
| 6745 | |
| 6746 // See the comment in coordinator_yield() | |
|
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6747 for (unsigned i = 0; |
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6748 i < CMSYieldSleepCount && |
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6749 ConcurrentMarkSweepThread::should_yield() && |
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6750 !CMSCollector::foregroundGCIsActive(); |
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6751 ++i) { |
| 0 | 6752 os::sleep(Thread::current(), 1, false); |
| 6753 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 6754 } | |
| 6755 | |
| 6756 ConcurrentMarkSweepThread::synchronize(true); | |
| 6757 _freelistLock->lock_without_safepoint_check(); | |
| 6758 _bit_map->lock()->lock_without_safepoint_check(); | |
| 6759 _collector->startTimer(); | |
| 6760 } | |
| 6761 | |
| 6762 /////////////////////////////////////////////////////////// | |
| 6763 // Par_MarkRefsIntoAndScanClosure: a parallel version of | |
| 6764 // MarkRefsIntoAndScanClosure | |
| 6765 /////////////////////////////////////////////////////////// | |
| 6766 Par_MarkRefsIntoAndScanClosure::Par_MarkRefsIntoAndScanClosure( | |
| 6767 CMSCollector* collector, MemRegion span, ReferenceProcessor* rp, | |
|
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6768 CMSBitMap* bit_map, OopTaskQueue* work_queue): |
| 0 | 6769 _span(span), |
| 6770 _bit_map(bit_map), | |
| 6771 _work_queue(work_queue), | |
| 6772 _low_water_mark(MIN2((uint)(work_queue->max_elems()/4), | |
| 6773 (uint)(CMSWorkQueueDrainThreshold * ParallelGCThreads))), | |
|
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6774 _par_pushAndMarkClosure(collector, span, rp, bit_map, work_queue) |
| 0 | 6775 { |
| 6776 _ref_processor = rp; | |
| 6777 assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL"); | |
| 6778 } | |
| 6779 | |
| 6780 // This closure is used to mark refs into the CMS generation at the | |
| 6781 // second (final) checkpoint, and to scan and transitively follow | |
| 6782 // the unmarked oops. The marks are made in the marking bit map and | |
| 6783 // the work_queue is used for keeping the (newly) grey objects during | |
| 6784 // the scan phase whence they are also available for stealing by parallel | |
| 6785 // threads. Since the marking bit map is shared, updates are | |
| 6786 // synchronized (via CAS). | |
|
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6787 void Par_MarkRefsIntoAndScanClosure::do_oop(oop obj) { |
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6788 if (obj != NULL) { |
| 0 | 6789 // Ignore mark word because this could be an already marked oop |
| 6790 // that may be chained at the end of the overflow list. | |
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6791 assert(obj->is_oop(true), "expected an oop"); |
|
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6792 HeapWord* addr = (HeapWord*)obj; |
| 0 | 6793 if (_span.contains(addr) && |
| 6794 !_bit_map->isMarked(addr)) { | |
| 6795 // mark bit map (object will become grey): | |
| 6796 // It is possible for several threads to be | |
| 6797 // trying to "claim" this object concurrently; | |
| 6798 // the unique thread that succeeds in marking the | |
| 6799 // object first will do the subsequent push on | |
| 6800 // to the work queue (or overflow list). | |
| 6801 if (_bit_map->par_mark(addr)) { | |
| 6802 // push on work_queue (which may not be empty), and trim the | |
| 6803 // queue to an appropriate length by applying this closure to | |
| 6804 // the oops in the oops popped from the stack (i.e. blacken the | |
| 6805 // grey objects) | |
|
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6806 bool res = _work_queue->push(obj); |
| 0 | 6807 assert(res, "Low water mark should be less than capacity?"); |
| 6808 trim_queue(_low_water_mark); | |
| 6809 } // Else, another thread claimed the object | |
| 6810 } | |
| 6811 } | |
| 6812 } | |
| 6813 | |
|
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6814 void Par_MarkRefsIntoAndScanClosure::do_oop(oop* p) { Par_MarkRefsIntoAndScanClosure::do_oop_work(p); } |
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6815 void Par_MarkRefsIntoAndScanClosure::do_oop(narrowOop* p) { Par_MarkRefsIntoAndScanClosure::do_oop_work(p); } |
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6816 |
| 0 | 6817 // This closure is used to rescan the marked objects on the dirty cards |
| 6818 // in the mod union table and the card table proper. | |
| 6819 size_t ScanMarkedObjectsAgainCarefullyClosure::do_object_careful_m( | |
| 6820 oop p, MemRegion mr) { | |
| 6821 | |
| 6822 size_t size = 0; | |
| 6823 HeapWord* addr = (HeapWord*)p; | |
| 6824 DEBUG_ONLY(_collector->verify_work_stacks_empty();) | |
| 6825 assert(_span.contains(addr), "we are scanning the CMS generation"); | |
| 6826 // check if it's time to yield | |
| 6827 if (do_yield_check()) { | |
| 6828 // We yielded for some foreground stop-world work, | |
| 6829 // and we have been asked to abort this ongoing preclean cycle. | |
| 6830 return 0; | |
| 6831 } | |
| 6832 if (_bitMap->isMarked(addr)) { | |
| 6833 // it's marked; is it potentially uninitialized? | |
| 187 | 6834 if (p->klass_or_null() != NULL) { |
| 0 | 6835 // an initialized object; ignore mark word in verification below |
| 6836 // since we are running concurrent with mutators | |
| 6837 assert(p->is_oop(true), "should be an oop"); | |
| 6838 if (p->is_objArray()) { | |
| 6839 // objArrays are precisely marked; restrict scanning | |
| 6840 // to dirty cards only. | |
| 187 | 6841 size = CompactibleFreeListSpace::adjustObjectSize( |
| 6842 p->oop_iterate(_scanningClosure, mr)); | |
| 0 | 6843 } else { |
| 6844 // A non-array may have been imprecisely marked; we need | |
| 6845 // to scan object in its entirety. | |
| 6846 size = CompactibleFreeListSpace::adjustObjectSize( | |
| 6847 p->oop_iterate(_scanningClosure)); | |
| 6848 } | |
| 6849 #ifdef DEBUG | |
| 6850 size_t direct_size = | |
| 6851 CompactibleFreeListSpace::adjustObjectSize(p->size()); | |
| 6852 assert(size == direct_size, "Inconsistency in size"); | |
| 6853 assert(size >= 3, "Necessary for Printezis marks to work"); | |
| 6854 if (!_bitMap->isMarked(addr+1)) { | |
| 6855 _bitMap->verifyNoOneBitsInRange(addr+2, addr+size); | |
| 6856 } else { | |
| 6857 _bitMap->verifyNoOneBitsInRange(addr+2, addr+size-1); | |
| 6858 assert(_bitMap->isMarked(addr+size-1), | |
| 6859 "inconsistent Printezis mark"); | |
| 6860 } | |
| 6861 #endif // DEBUG | |
| 6862 } else { | |
| 6863 // an unitialized object | |
| 6864 assert(_bitMap->isMarked(addr+1), "missing Printezis mark?"); | |
| 6865 HeapWord* nextOneAddr = _bitMap->getNextMarkedWordAddress(addr + 2); | |
| 6866 size = pointer_delta(nextOneAddr + 1, addr); | |
| 6867 assert(size == CompactibleFreeListSpace::adjustObjectSize(size), | |
| 6868 "alignment problem"); | |
| 6869 // Note that pre-cleaning needn't redirty the card. OopDesc::set_klass() | |
| 6870 // will dirty the card when the klass pointer is installed in the | |
| 6871 // object (signalling the completion of initialization). | |
| 6872 } | |
| 6873 } else { | |
| 6874 // Either a not yet marked object or an uninitialized object | |
|
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6875 if (p->klass_or_null() == NULL) { |
| 0 | 6876 // An uninitialized object, skip to the next card, since |
| 6877 // we may not be able to read its P-bits yet. | |
| 6878 assert(size == 0, "Initial value"); | |
| 6879 } else { | |
| 6880 // An object not (yet) reached by marking: we merely need to | |
| 6881 // compute its size so as to go look at the next block. | |
| 6882 assert(p->is_oop(true), "should be an oop"); | |
| 6883 size = CompactibleFreeListSpace::adjustObjectSize(p->size()); | |
| 6884 } | |
| 6885 } | |
| 6886 DEBUG_ONLY(_collector->verify_work_stacks_empty();) | |
| 6887 return size; | |
| 6888 } | |
| 6889 | |
| 6890 void ScanMarkedObjectsAgainCarefullyClosure::do_yield_work() { | |
| 6891 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 6892 "CMS thread should hold CMS token"); | |
| 6893 assert_lock_strong(_freelistLock); | |
| 6894 assert_lock_strong(_bitMap->lock()); | |
| 6895 // relinquish the free_list_lock and bitMaplock() | |
| 6896 _bitMap->lock()->unlock(); | |
| 6897 _freelistLock->unlock(); | |
| 6898 ConcurrentMarkSweepThread::desynchronize(true); | |
| 6899 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 6900 _collector->stopTimer(); | |
| 6901 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 6902 if (PrintCMSStatistics != 0) { | |
| 6903 _collector->incrementYields(); | |
| 6904 } | |
| 6905 _collector->icms_wait(); | |
| 6906 | |
| 6907 // See the comment in coordinator_yield() | |
| 6908 for (unsigned i = 0; i < CMSYieldSleepCount && | |
|
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6909 ConcurrentMarkSweepThread::should_yield() && |
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6910 !CMSCollector::foregroundGCIsActive(); ++i) { |
| 0 | 6911 os::sleep(Thread::current(), 1, false); |
| 6912 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 6913 } | |
| 6914 | |
| 6915 ConcurrentMarkSweepThread::synchronize(true); | |
| 6916 _freelistLock->lock_without_safepoint_check(); | |
| 6917 _bitMap->lock()->lock_without_safepoint_check(); | |
| 6918 _collector->startTimer(); | |
| 6919 } | |
| 6920 | |
| 6921 | |
| 6922 ////////////////////////////////////////////////////////////////// | |
| 6923 // SurvivorSpacePrecleanClosure | |
| 6924 ////////////////////////////////////////////////////////////////// | |
| 6925 // This (single-threaded) closure is used to preclean the oops in | |
| 6926 // the survivor spaces. | |
| 6927 size_t SurvivorSpacePrecleanClosure::do_object_careful(oop p) { | |
| 6928 | |
| 6929 HeapWord* addr = (HeapWord*)p; | |
| 6930 DEBUG_ONLY(_collector->verify_work_stacks_empty();) | |
| 6931 assert(!_span.contains(addr), "we are scanning the survivor spaces"); | |
| 187 | 6932 assert(p->klass_or_null() != NULL, "object should be initializd"); |
| 0 | 6933 // an initialized object; ignore mark word in verification below |
| 6934 // since we are running concurrent with mutators | |
| 6935 assert(p->is_oop(true), "should be an oop"); | |
| 6936 // Note that we do not yield while we iterate over | |
| 6937 // the interior oops of p, pushing the relevant ones | |
| 6938 // on our marking stack. | |
| 6939 size_t size = p->oop_iterate(_scanning_closure); | |
| 6940 do_yield_check(); | |
| 6941 // Observe that below, we do not abandon the preclean | |
| 6942 // phase as soon as we should; rather we empty the | |
| 6943 // marking stack before returning. This is to satisfy | |
| 6944 // some existing assertions. In general, it may be a | |
| 6945 // good idea to abort immediately and complete the marking | |
| 6946 // from the grey objects at a later time. | |
| 6947 while (!_mark_stack->isEmpty()) { | |
| 6948 oop new_oop = _mark_stack->pop(); | |
| 6949 assert(new_oop != NULL && new_oop->is_oop(), "Expected an oop"); | |
| 6950 assert(_bit_map->isMarked((HeapWord*)new_oop), | |
| 6951 "only grey objects on this stack"); | |
| 6952 // iterate over the oops in this oop, marking and pushing | |
| 6953 // the ones in CMS heap (i.e. in _span). | |
| 6954 new_oop->oop_iterate(_scanning_closure); | |
| 6955 // check if it's time to yield | |
| 6956 do_yield_check(); | |
| 6957 } | |
| 6958 unsigned int after_count = | |
| 6959 GenCollectedHeap::heap()->total_collections(); | |
| 6960 bool abort = (_before_count != after_count) || | |
| 6961 _collector->should_abort_preclean(); | |
| 6962 return abort ? 0 : size; | |
| 6963 } | |
| 6964 | |
| 6965 void SurvivorSpacePrecleanClosure::do_yield_work() { | |
| 6966 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 6967 "CMS thread should hold CMS token"); | |
| 6968 assert_lock_strong(_bit_map->lock()); | |
| 6969 // Relinquish the bit map lock | |
| 6970 _bit_map->lock()->unlock(); | |
| 6971 ConcurrentMarkSweepThread::desynchronize(true); | |
| 6972 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 6973 _collector->stopTimer(); | |
| 6974 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 6975 if (PrintCMSStatistics != 0) { | |
| 6976 _collector->incrementYields(); | |
| 6977 } | |
| 6978 _collector->icms_wait(); | |
| 6979 | |
| 6980 // See the comment in coordinator_yield() | |
| 6981 for (unsigned i = 0; i < CMSYieldSleepCount && | |
| 6982 ConcurrentMarkSweepThread::should_yield() && | |
| 6983 !CMSCollector::foregroundGCIsActive(); ++i) { | |
| 6984 os::sleep(Thread::current(), 1, false); | |
| 6985 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 6986 } | |
| 6987 | |
| 6988 ConcurrentMarkSweepThread::synchronize(true); | |
| 6989 _bit_map->lock()->lock_without_safepoint_check(); | |
| 6990 _collector->startTimer(); | |
| 6991 } | |
| 6992 | |
| 6993 // This closure is used to rescan the marked objects on the dirty cards | |
| 6994 // in the mod union table and the card table proper. In the parallel | |
| 6995 // case, although the bitMap is shared, we do a single read so the | |
| 6996 // isMarked() query is "safe". | |
| 6997 bool ScanMarkedObjectsAgainClosure::do_object_bm(oop p, MemRegion mr) { | |
| 6998 // Ignore mark word because we are running concurrent with mutators | |
| 6999 assert(p->is_oop_or_null(true), "expected an oop or null"); | |
| 7000 HeapWord* addr = (HeapWord*)p; | |
| 7001 assert(_span.contains(addr), "we are scanning the CMS generation"); | |
| 7002 bool is_obj_array = false; | |
| 7003 #ifdef DEBUG | |
| 7004 if (!_parallel) { | |
| 7005 assert(_mark_stack->isEmpty(), "pre-condition (eager drainage)"); | |
| 7006 assert(_collector->overflow_list_is_empty(), | |
| 7007 "overflow list should be empty"); | |
| 7008 | |
| 7009 } | |
| 7010 #endif // DEBUG | |
| 7011 if (_bit_map->isMarked(addr)) { | |
| 7012 // Obj arrays are precisely marked, non-arrays are not; | |
| 7013 // so we scan objArrays precisely and non-arrays in their | |
| 7014 // entirety. | |
| 7015 if (p->is_objArray()) { | |
| 7016 is_obj_array = true; | |
| 7017 if (_parallel) { | |
| 7018 p->oop_iterate(_par_scan_closure, mr); | |
| 7019 } else { | |
| 7020 p->oop_iterate(_scan_closure, mr); | |
| 7021 } | |
| 7022 } else { | |
| 7023 if (_parallel) { | |
| 7024 p->oop_iterate(_par_scan_closure); | |
| 7025 } else { | |
| 7026 p->oop_iterate(_scan_closure); | |
| 7027 } | |
| 7028 } | |
| 7029 } | |
| 7030 #ifdef DEBUG | |
| 7031 if (!_parallel) { | |
| 7032 assert(_mark_stack->isEmpty(), "post-condition (eager drainage)"); | |
| 7033 assert(_collector->overflow_list_is_empty(), | |
| 7034 "overflow list should be empty"); | |
| 7035 | |
| 7036 } | |
| 7037 #endif // DEBUG | |
| 7038 return is_obj_array; | |
| 7039 } | |
| 7040 | |
| 7041 MarkFromRootsClosure::MarkFromRootsClosure(CMSCollector* collector, | |
| 7042 MemRegion span, | |
| 7043 CMSBitMap* bitMap, CMSMarkStack* markStack, | |
| 7044 bool should_yield, bool verifying): | |
| 7045 _collector(collector), | |
| 7046 _span(span), | |
| 7047 _bitMap(bitMap), | |
| 7048 _mut(&collector->_modUnionTable), | |
| 7049 _markStack(markStack), | |
| 7050 _yield(should_yield), | |
| 7051 _skipBits(0) | |
| 7052 { | |
| 7053 assert(_markStack->isEmpty(), "stack should be empty"); | |
| 7054 _finger = _bitMap->startWord(); | |
| 7055 _threshold = _finger; | |
| 7056 assert(_collector->_restart_addr == NULL, "Sanity check"); | |
| 7057 assert(_span.contains(_finger), "Out of bounds _finger?"); | |
| 7058 DEBUG_ONLY(_verifying = verifying;) | |
| 7059 } | |
| 7060 | |
| 7061 void MarkFromRootsClosure::reset(HeapWord* addr) { | |
| 7062 assert(_markStack->isEmpty(), "would cause duplicates on stack"); | |
| 7063 assert(_span.contains(addr), "Out of bounds _finger?"); | |
| 7064 _finger = addr; | |
| 7065 _threshold = (HeapWord*)round_to( | |
| 7066 (intptr_t)_finger, CardTableModRefBS::card_size); | |
| 7067 } | |
| 7068 | |
| 7069 // Should revisit to see if this should be restructured for | |
| 7070 // greater efficiency. | |
|
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7071 bool MarkFromRootsClosure::do_bit(size_t offset) { |
| 0 | 7072 if (_skipBits > 0) { |
| 7073 _skipBits--; | |
|
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7074 return true; |
| 0 | 7075 } |
| 7076 // convert offset into a HeapWord* | |
| 7077 HeapWord* addr = _bitMap->startWord() + offset; | |
| 7078 assert(_bitMap->endWord() && addr < _bitMap->endWord(), | |
| 7079 "address out of range"); | |
| 7080 assert(_bitMap->isMarked(addr), "tautology"); | |
| 7081 if (_bitMap->isMarked(addr+1)) { | |
| 7082 // this is an allocated but not yet initialized object | |
| 7083 assert(_skipBits == 0, "tautology"); | |
| 7084 _skipBits = 2; // skip next two marked bits ("Printezis-marks") | |
| 7085 oop p = oop(addr); | |
|
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7086 if (p->klass_or_null() == NULL) { |
| 0 | 7087 DEBUG_ONLY(if (!_verifying) {) |
| 7088 // We re-dirty the cards on which this object lies and increase | |
| 7089 // the _threshold so that we'll come back to scan this object | |
| 7090 // during the preclean or remark phase. (CMSCleanOnEnter) | |
| 7091 if (CMSCleanOnEnter) { | |
| 7092 size_t sz = _collector->block_size_using_printezis_bits(addr); | |
| 7093 HeapWord* end_card_addr = (HeapWord*)round_to( | |
| 7094 (intptr_t)(addr+sz), CardTableModRefBS::card_size); | |
|
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7095 MemRegion redirty_range = MemRegion(addr, end_card_addr); |
| 0 | 7096 assert(!redirty_range.is_empty(), "Arithmetical tautology"); |
| 7097 // Bump _threshold to end_card_addr; note that | |
| 7098 // _threshold cannot possibly exceed end_card_addr, anyhow. | |
| 7099 // This prevents future clearing of the card as the scan proceeds | |
| 7100 // to the right. | |
| 7101 assert(_threshold <= end_card_addr, | |
| 7102 "Because we are just scanning into this object"); | |
| 7103 if (_threshold < end_card_addr) { | |
| 7104 _threshold = end_card_addr; | |
| 7105 } | |
| 187 | 7106 if (p->klass_or_null() != NULL) { |
| 0 | 7107 // Redirty the range of cards... |
| 7108 _mut->mark_range(redirty_range); | |
| 7109 } // ...else the setting of klass will dirty the card anyway. | |
| 7110 } | |
| 7111 DEBUG_ONLY(}) | |
|
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7112 return true; |
| 0 | 7113 } |
| 7114 } | |
| 7115 scanOopsInOop(addr); | |
|
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7116 return true; |
| 0 | 7117 } |
| 7118 | |
| 7119 // We take a break if we've been at this for a while, | |
| 7120 // so as to avoid monopolizing the locks involved. | |
| 7121 void MarkFromRootsClosure::do_yield_work() { | |
| 7122 // First give up the locks, then yield, then re-lock | |
| 7123 // We should probably use a constructor/destructor idiom to | |
| 7124 // do this unlock/lock or modify the MutexUnlocker class to | |
| 7125 // serve our purpose. XXX | |
| 7126 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 7127 "CMS thread should hold CMS token"); | |
| 7128 assert_lock_strong(_bitMap->lock()); | |
| 7129 _bitMap->lock()->unlock(); | |
| 7130 ConcurrentMarkSweepThread::desynchronize(true); | |
| 7131 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7132 _collector->stopTimer(); | |
| 7133 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 7134 if (PrintCMSStatistics != 0) { | |
| 7135 _collector->incrementYields(); | |
| 7136 } | |
| 7137 _collector->icms_wait(); | |
| 7138 | |
| 7139 // See the comment in coordinator_yield() | |
| 7140 for (unsigned i = 0; i < CMSYieldSleepCount && | |
| 7141 ConcurrentMarkSweepThread::should_yield() && | |
| 7142 !CMSCollector::foregroundGCIsActive(); ++i) { | |
| 7143 os::sleep(Thread::current(), 1, false); | |
| 7144 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7145 } | |
| 7146 | |
| 7147 ConcurrentMarkSweepThread::synchronize(true); | |
| 7148 _bitMap->lock()->lock_without_safepoint_check(); | |
| 7149 _collector->startTimer(); | |
| 7150 } | |
| 7151 | |
| 7152 void MarkFromRootsClosure::scanOopsInOop(HeapWord* ptr) { | |
| 7153 assert(_bitMap->isMarked(ptr), "expected bit to be set"); | |
| 7154 assert(_markStack->isEmpty(), | |
| 7155 "should drain stack to limit stack usage"); | |
| 7156 // convert ptr to an oop preparatory to scanning | |
|
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7157 oop obj = oop(ptr); |
| 0 | 7158 // Ignore mark word in verification below, since we |
| 7159 // may be running concurrent with mutators. | |
|
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7160 assert(obj->is_oop(true), "should be an oop"); |
| 0 | 7161 assert(_finger <= ptr, "_finger runneth ahead"); |
| 7162 // advance the finger to right end of this object | |
|
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7163 _finger = ptr + obj->size(); |
| 0 | 7164 assert(_finger > ptr, "we just incremented it above"); |
| 7165 // On large heaps, it may take us some time to get through | |
| 7166 // the marking phase (especially if running iCMS). During | |
| 7167 // this time it's possible that a lot of mutations have | |
| 7168 // accumulated in the card table and the mod union table -- | |
| 7169 // these mutation records are redundant until we have | |
| 7170 // actually traced into the corresponding card. | |
| 7171 // Here, we check whether advancing the finger would make | |
| 7172 // us cross into a new card, and if so clear corresponding | |
| 7173 // cards in the MUT (preclean them in the card-table in the | |
| 7174 // future). | |
| 7175 | |
| 7176 DEBUG_ONLY(if (!_verifying) {) | |
| 7177 // The clean-on-enter optimization is disabled by default, | |
| 7178 // until we fix 6178663. | |
| 7179 if (CMSCleanOnEnter && (_finger > _threshold)) { | |
| 7180 // [_threshold, _finger) represents the interval | |
| 7181 // of cards to be cleared in MUT (or precleaned in card table). | |
| 7182 // The set of cards to be cleared is all those that overlap | |
| 7183 // with the interval [_threshold, _finger); note that | |
| 7184 // _threshold is always kept card-aligned but _finger isn't | |
| 7185 // always card-aligned. | |
| 7186 HeapWord* old_threshold = _threshold; | |
| 7187 assert(old_threshold == (HeapWord*)round_to( | |
| 7188 (intptr_t)old_threshold, CardTableModRefBS::card_size), | |
| 7189 "_threshold should always be card-aligned"); | |
| 7190 _threshold = (HeapWord*)round_to( | |
| 7191 (intptr_t)_finger, CardTableModRefBS::card_size); | |
| 7192 MemRegion mr(old_threshold, _threshold); | |
| 7193 assert(!mr.is_empty(), "Control point invariant"); | |
| 7194 assert(_span.contains(mr), "Should clear within span"); | |
| 7195 _mut->clear_range(mr); | |
| 7196 } | |
| 7197 DEBUG_ONLY(}) | |
| 7198 // Note: the finger doesn't advance while we drain | |
| 7199 // the stack below. | |
| 7200 PushOrMarkClosure pushOrMarkClosure(_collector, | |
| 7201 _span, _bitMap, _markStack, | |
| 7202 _finger, this); | |
|
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7203 bool res = _markStack->push(obj); |
| 0 | 7204 assert(res, "Empty non-zero size stack should have space for single push"); |
| 7205 while (!_markStack->isEmpty()) { | |
| 7206 oop new_oop = _markStack->pop(); | |
| 7207 // Skip verifying header mark word below because we are | |
| 7208 // running concurrent with mutators. | |
| 7209 assert(new_oop->is_oop(true), "Oops! expected to pop an oop"); | |
| 7210 // now scan this oop's oops | |
| 7211 new_oop->oop_iterate(&pushOrMarkClosure); | |
| 7212 do_yield_check(); | |
| 7213 } | |
| 7214 assert(_markStack->isEmpty(), "tautology, emphasizing post-condition"); | |
| 7215 } | |
| 7216 | |
| 7217 Par_MarkFromRootsClosure::Par_MarkFromRootsClosure(CMSConcMarkingTask* task, | |
| 7218 CMSCollector* collector, MemRegion span, | |
| 7219 CMSBitMap* bit_map, | |
| 7220 OopTaskQueue* work_queue, | |
| 7221 CMSMarkStack* overflow_stack, | |
| 7222 bool should_yield): | |
| 7223 _collector(collector), | |
| 7224 _whole_span(collector->_span), | |
| 7225 _span(span), | |
| 7226 _bit_map(bit_map), | |
| 7227 _mut(&collector->_modUnionTable), | |
| 7228 _work_queue(work_queue), | |
| 7229 _overflow_stack(overflow_stack), | |
| 7230 _yield(should_yield), | |
| 7231 _skip_bits(0), | |
| 7232 _task(task) | |
| 7233 { | |
| 7234 assert(_work_queue->size() == 0, "work_queue should be empty"); | |
| 7235 _finger = span.start(); | |
| 7236 _threshold = _finger; // XXX Defer clear-on-enter optimization for now | |
| 7237 assert(_span.contains(_finger), "Out of bounds _finger?"); | |
| 7238 } | |
| 7239 | |
| 7240 // Should revisit to see if this should be restructured for | |
| 7241 // greater efficiency. | |
|
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7242 bool Par_MarkFromRootsClosure::do_bit(size_t offset) { |
| 0 | 7243 if (_skip_bits > 0) { |
| 7244 _skip_bits--; | |
|
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7245 return true; |
| 0 | 7246 } |
| 7247 // convert offset into a HeapWord* | |
| 7248 HeapWord* addr = _bit_map->startWord() + offset; | |
| 7249 assert(_bit_map->endWord() && addr < _bit_map->endWord(), | |
| 7250 "address out of range"); | |
| 7251 assert(_bit_map->isMarked(addr), "tautology"); | |
| 7252 if (_bit_map->isMarked(addr+1)) { | |
| 7253 // this is an allocated object that might not yet be initialized | |
| 7254 assert(_skip_bits == 0, "tautology"); | |
| 7255 _skip_bits = 2; // skip next two marked bits ("Printezis-marks") | |
| 7256 oop p = oop(addr); | |
|
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7257 if (p->klass_or_null() == NULL) { |
| 0 | 7258 // in the case of Clean-on-Enter optimization, redirty card |
| 7259 // and avoid clearing card by increasing the threshold. | |
|
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7260 return true; |
| 0 | 7261 } |
| 7262 } | |
| 7263 scan_oops_in_oop(addr); | |
|
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7264 return true; |
| 0 | 7265 } |
| 7266 | |
| 7267 void Par_MarkFromRootsClosure::scan_oops_in_oop(HeapWord* ptr) { | |
| 7268 assert(_bit_map->isMarked(ptr), "expected bit to be set"); | |
| 7269 // Should we assert that our work queue is empty or | |
| 7270 // below some drain limit? | |
| 7271 assert(_work_queue->size() == 0, | |
| 7272 "should drain stack to limit stack usage"); | |
| 7273 // convert ptr to an oop preparatory to scanning | |
|
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7274 oop obj = oop(ptr); |
| 0 | 7275 // Ignore mark word in verification below, since we |
| 7276 // may be running concurrent with mutators. | |
|
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7277 assert(obj->is_oop(true), "should be an oop"); |
| 0 | 7278 assert(_finger <= ptr, "_finger runneth ahead"); |
| 7279 // advance the finger to right end of this object | |
|
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7280 _finger = ptr + obj->size(); |
| 0 | 7281 assert(_finger > ptr, "we just incremented it above"); |
| 7282 // On large heaps, it may take us some time to get through | |
| 7283 // the marking phase (especially if running iCMS). During | |
| 7284 // this time it's possible that a lot of mutations have | |
| 7285 // accumulated in the card table and the mod union table -- | |
| 7286 // these mutation records are redundant until we have | |
| 7287 // actually traced into the corresponding card. | |
| 7288 // Here, we check whether advancing the finger would make | |
| 7289 // us cross into a new card, and if so clear corresponding | |
| 7290 // cards in the MUT (preclean them in the card-table in the | |
| 7291 // future). | |
| 7292 | |
| 7293 // The clean-on-enter optimization is disabled by default, | |
| 7294 // until we fix 6178663. | |
| 7295 if (CMSCleanOnEnter && (_finger > _threshold)) { | |
| 7296 // [_threshold, _finger) represents the interval | |
| 7297 // of cards to be cleared in MUT (or precleaned in card table). | |
| 7298 // The set of cards to be cleared is all those that overlap | |
| 7299 // with the interval [_threshold, _finger); note that | |
| 7300 // _threshold is always kept card-aligned but _finger isn't | |
| 7301 // always card-aligned. | |
| 7302 HeapWord* old_threshold = _threshold; | |
| 7303 assert(old_threshold == (HeapWord*)round_to( | |
| 7304 (intptr_t)old_threshold, CardTableModRefBS::card_size), | |
| 7305 "_threshold should always be card-aligned"); | |
| 7306 _threshold = (HeapWord*)round_to( | |
| 7307 (intptr_t)_finger, CardTableModRefBS::card_size); | |
| 7308 MemRegion mr(old_threshold, _threshold); | |
| 7309 assert(!mr.is_empty(), "Control point invariant"); | |
| 7310 assert(_span.contains(mr), "Should clear within span"); // _whole_span ?? | |
| 7311 _mut->clear_range(mr); | |
| 7312 } | |
| 7313 | |
| 7314 // Note: the local finger doesn't advance while we drain | |
| 7315 // the stack below, but the global finger sure can and will. | |
| 7316 HeapWord** gfa = _task->global_finger_addr(); | |
| 7317 Par_PushOrMarkClosure pushOrMarkClosure(_collector, | |
| 7318 _span, _bit_map, | |
| 7319 _work_queue, | |
| 7320 _overflow_stack, | |
| 7321 _finger, | |
| 7322 gfa, this); | |
|
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7323 bool res = _work_queue->push(obj); // overflow could occur here |
| 0 | 7324 assert(res, "Will hold once we use workqueues"); |
| 7325 while (true) { | |
| 7326 oop new_oop; | |
| 7327 if (!_work_queue->pop_local(new_oop)) { | |
| 7328 // We emptied our work_queue; check if there's stuff that can | |
| 7329 // be gotten from the overflow stack. | |
| 7330 if (CMSConcMarkingTask::get_work_from_overflow_stack( | |
| 7331 _overflow_stack, _work_queue)) { | |
| 7332 do_yield_check(); | |
| 7333 continue; | |
| 7334 } else { // done | |
| 7335 break; | |
| 7336 } | |
| 7337 } | |
| 7338 // Skip verifying header mark word below because we are | |
| 7339 // running concurrent with mutators. | |
| 7340 assert(new_oop->is_oop(true), "Oops! expected to pop an oop"); | |
| 7341 // now scan this oop's oops | |
| 7342 new_oop->oop_iterate(&pushOrMarkClosure); | |
| 7343 do_yield_check(); | |
| 7344 } | |
| 7345 assert(_work_queue->size() == 0, "tautology, emphasizing post-condition"); | |
| 7346 } | |
| 7347 | |
| 7348 // Yield in response to a request from VM Thread or | |
| 7349 // from mutators. | |
| 7350 void Par_MarkFromRootsClosure::do_yield_work() { | |
| 7351 assert(_task != NULL, "sanity"); | |
| 7352 _task->yield(); | |
| 7353 } | |
| 7354 | |
| 7355 // A variant of the above used for verifying CMS marking work. | |
| 7356 MarkFromRootsVerifyClosure::MarkFromRootsVerifyClosure(CMSCollector* collector, | |
| 7357 MemRegion span, | |
| 7358 CMSBitMap* verification_bm, CMSBitMap* cms_bm, | |
| 7359 CMSMarkStack* mark_stack): | |
| 7360 _collector(collector), | |
| 7361 _span(span), | |
| 7362 _verification_bm(verification_bm), | |
| 7363 _cms_bm(cms_bm), | |
| 7364 _mark_stack(mark_stack), | |
| 7365 _pam_verify_closure(collector, span, verification_bm, cms_bm, | |
| 7366 mark_stack) | |
| 7367 { | |
| 7368 assert(_mark_stack->isEmpty(), "stack should be empty"); | |
| 7369 _finger = _verification_bm->startWord(); | |
| 7370 assert(_collector->_restart_addr == NULL, "Sanity check"); | |
| 7371 assert(_span.contains(_finger), "Out of bounds _finger?"); | |
| 7372 } | |
| 7373 | |
| 7374 void MarkFromRootsVerifyClosure::reset(HeapWord* addr) { | |
| 7375 assert(_mark_stack->isEmpty(), "would cause duplicates on stack"); | |
| 7376 assert(_span.contains(addr), "Out of bounds _finger?"); | |
| 7377 _finger = addr; | |
| 7378 } | |
| 7379 | |
| 7380 // Should revisit to see if this should be restructured for | |
| 7381 // greater efficiency. | |
|
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7382 bool MarkFromRootsVerifyClosure::do_bit(size_t offset) { |
| 0 | 7383 // convert offset into a HeapWord* |
| 7384 HeapWord* addr = _verification_bm->startWord() + offset; | |
| 7385 assert(_verification_bm->endWord() && addr < _verification_bm->endWord(), | |
| 7386 "address out of range"); | |
| 7387 assert(_verification_bm->isMarked(addr), "tautology"); | |
| 7388 assert(_cms_bm->isMarked(addr), "tautology"); | |
| 7389 | |
| 7390 assert(_mark_stack->isEmpty(), | |
| 7391 "should drain stack to limit stack usage"); | |
| 7392 // convert addr to an oop preparatory to scanning | |
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7393 oop obj = oop(addr); |
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7394 assert(obj->is_oop(), "should be an oop"); |
| 0 | 7395 assert(_finger <= addr, "_finger runneth ahead"); |
| 7396 // advance the finger to right end of this object | |
|
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7397 _finger = addr + obj->size(); |
| 0 | 7398 assert(_finger > addr, "we just incremented it above"); |
| 7399 // Note: the finger doesn't advance while we drain | |
| 7400 // the stack below. | |
|
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7401 bool res = _mark_stack->push(obj); |
| 0 | 7402 assert(res, "Empty non-zero size stack should have space for single push"); |
| 7403 while (!_mark_stack->isEmpty()) { | |
| 7404 oop new_oop = _mark_stack->pop(); | |
| 7405 assert(new_oop->is_oop(), "Oops! expected to pop an oop"); | |
| 7406 // now scan this oop's oops | |
| 7407 new_oop->oop_iterate(&_pam_verify_closure); | |
| 7408 } | |
| 7409 assert(_mark_stack->isEmpty(), "tautology, emphasizing post-condition"); | |
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7410 return true; |
| 0 | 7411 } |
| 7412 | |
| 7413 PushAndMarkVerifyClosure::PushAndMarkVerifyClosure( | |
| 7414 CMSCollector* collector, MemRegion span, | |
| 7415 CMSBitMap* verification_bm, CMSBitMap* cms_bm, | |
| 7416 CMSMarkStack* mark_stack): | |
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7417 CMSOopClosure(collector->ref_processor()), |
| 0 | 7418 _collector(collector), |
| 7419 _span(span), | |
| 7420 _verification_bm(verification_bm), | |
| 7421 _cms_bm(cms_bm), | |
| 7422 _mark_stack(mark_stack) | |
| 7423 { } | |
| 7424 | |
|
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7425 void PushAndMarkVerifyClosure::do_oop(oop* p) { PushAndMarkVerifyClosure::do_oop_work(p); } |
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7426 void PushAndMarkVerifyClosure::do_oop(narrowOop* p) { PushAndMarkVerifyClosure::do_oop_work(p); } |
| 0 | 7427 |
| 7428 // Upon stack overflow, we discard (part of) the stack, | |
| 7429 // remembering the least address amongst those discarded | |
| 7430 // in CMSCollector's _restart_address. | |
| 7431 void PushAndMarkVerifyClosure::handle_stack_overflow(HeapWord* lost) { | |
| 7432 // Remember the least grey address discarded | |
| 7433 HeapWord* ra = (HeapWord*)_mark_stack->least_value(lost); | |
| 7434 _collector->lower_restart_addr(ra); | |
| 7435 _mark_stack->reset(); // discard stack contents | |
| 7436 _mark_stack->expand(); // expand the stack if possible | |
| 7437 } | |
| 7438 | |
|
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7439 void PushAndMarkVerifyClosure::do_oop(oop obj) { |
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7440 assert(obj->is_oop_or_null(), "expected an oop or NULL"); |
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7441 HeapWord* addr = (HeapWord*)obj; |
| 0 | 7442 if (_span.contains(addr) && !_verification_bm->isMarked(addr)) { |
| 7443 // Oop lies in _span and isn't yet grey or black | |
| 7444 _verification_bm->mark(addr); // now grey | |
| 7445 if (!_cms_bm->isMarked(addr)) { | |
| 7446 oop(addr)->print(); | |
|
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7447 gclog_or_tty->print_cr(" (" INTPTR_FORMAT " should have been marked)", |
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7448 addr); |
| 0 | 7449 fatal("... aborting"); |
| 7450 } | |
| 7451 | |
|
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7452 if (!_mark_stack->push(obj)) { // stack overflow |
| 0 | 7453 if (PrintCMSStatistics != 0) { |
| 7454 gclog_or_tty->print_cr("CMS marking stack overflow (benign) at " | |
| 7455 SIZE_FORMAT, _mark_stack->capacity()); | |
| 7456 } | |
| 7457 assert(_mark_stack->isFull(), "Else push should have succeeded"); | |
| 7458 handle_stack_overflow(addr); | |
| 7459 } | |
| 7460 // anything including and to the right of _finger | |
| 7461 // will be scanned as we iterate over the remainder of the | |
| 7462 // bit map | |
| 7463 } | |
| 7464 } | |
| 7465 | |
| 7466 PushOrMarkClosure::PushOrMarkClosure(CMSCollector* collector, | |
| 7467 MemRegion span, | |
| 7468 CMSBitMap* bitMap, CMSMarkStack* markStack, | |
| 7469 HeapWord* finger, MarkFromRootsClosure* parent) : | |
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7470 CMSOopClosure(collector->ref_processor()), |
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7471 _collector(collector), |
| 0 | 7472 _span(span), |
| 7473 _bitMap(bitMap), | |
| 7474 _markStack(markStack), | |
| 7475 _finger(finger), | |
| 935 | 7476 _parent(parent) |
| 0 | 7477 { } |
| 7478 | |
| 7479 Par_PushOrMarkClosure::Par_PushOrMarkClosure(CMSCollector* collector, | |
| 7480 MemRegion span, | |
| 7481 CMSBitMap* bit_map, | |
| 7482 OopTaskQueue* work_queue, | |
| 7483 CMSMarkStack* overflow_stack, | |
| 7484 HeapWord* finger, | |
| 7485 HeapWord** global_finger_addr, | |
| 7486 Par_MarkFromRootsClosure* parent) : | |
|
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7487 CMSOopClosure(collector->ref_processor()), |
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7488 _collector(collector), |
| 0 | 7489 _whole_span(collector->_span), |
| 7490 _span(span), | |
| 7491 _bit_map(bit_map), | |
| 7492 _work_queue(work_queue), | |
| 7493 _overflow_stack(overflow_stack), | |
| 7494 _finger(finger), | |
| 7495 _global_finger_addr(global_finger_addr), | |
| 935 | 7496 _parent(parent) |
| 0 | 7497 { } |
| 7498 | |
|
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7499 // Assumes thread-safe access by callers, who are |
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7500 // responsible for mutual exclusion. |
| 0 | 7501 void CMSCollector::lower_restart_addr(HeapWord* low) { |
| 7502 assert(_span.contains(low), "Out of bounds addr"); | |
| 7503 if (_restart_addr == NULL) { | |
| 7504 _restart_addr = low; | |
| 7505 } else { | |
| 7506 _restart_addr = MIN2(_restart_addr, low); | |
| 7507 } | |
| 7508 } | |
| 7509 | |
| 7510 // Upon stack overflow, we discard (part of) the stack, | |
| 7511 // remembering the least address amongst those discarded | |
| 7512 // in CMSCollector's _restart_address. | |
| 7513 void PushOrMarkClosure::handle_stack_overflow(HeapWord* lost) { | |
| 7514 // Remember the least grey address discarded | |
| 7515 HeapWord* ra = (HeapWord*)_markStack->least_value(lost); | |
| 7516 _collector->lower_restart_addr(ra); | |
| 7517 _markStack->reset(); // discard stack contents | |
| 7518 _markStack->expand(); // expand the stack if possible | |
| 7519 } | |
| 7520 | |
| 7521 // Upon stack overflow, we discard (part of) the stack, | |
| 7522 // remembering the least address amongst those discarded | |
| 7523 // in CMSCollector's _restart_address. | |
| 7524 void Par_PushOrMarkClosure::handle_stack_overflow(HeapWord* lost) { | |
| 7525 // We need to do this under a mutex to prevent other | |
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7526 // workers from interfering with the work done below. |
| 0 | 7527 MutexLockerEx ml(_overflow_stack->par_lock(), |
| 7528 Mutex::_no_safepoint_check_flag); | |
| 7529 // Remember the least grey address discarded | |
| 7530 HeapWord* ra = (HeapWord*)_overflow_stack->least_value(lost); | |
| 7531 _collector->lower_restart_addr(ra); | |
| 7532 _overflow_stack->reset(); // discard stack contents | |
| 7533 _overflow_stack->expand(); // expand the stack if possible | |
| 7534 } | |
| 7535 | |
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7536 void CMKlassClosure::do_klass(Klass* k) { |
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7537 assert(_oop_closure != NULL, "Not initialized?"); |
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7538 k->oops_do(_oop_closure); |
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7539 } |
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7540 |
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7541 void PushOrMarkClosure::do_oop(oop obj) { |
| 0 | 7542 // Ignore mark word because we are running concurrent with mutators. |
|
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7543 assert(obj->is_oop_or_null(true), "expected an oop or NULL"); |
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7544 HeapWord* addr = (HeapWord*)obj; |
| 0 | 7545 if (_span.contains(addr) && !_bitMap->isMarked(addr)) { |
| 7546 // Oop lies in _span and isn't yet grey or black | |
| 7547 _bitMap->mark(addr); // now grey | |
| 7548 if (addr < _finger) { | |
| 7549 // the bit map iteration has already either passed, or | |
| 7550 // sampled, this bit in the bit map; we'll need to | |
| 7551 // use the marking stack to scan this oop's oops. | |
| 7552 bool simulate_overflow = false; | |
| 7553 NOT_PRODUCT( | |
| 7554 if (CMSMarkStackOverflowALot && | |
| 7555 _collector->simulate_overflow()) { | |
| 7556 // simulate a stack overflow | |
| 7557 simulate_overflow = true; | |
| 7558 } | |
| 7559 ) | |
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7560 if (simulate_overflow || !_markStack->push(obj)) { // stack overflow |
| 0 | 7561 if (PrintCMSStatistics != 0) { |
| 7562 gclog_or_tty->print_cr("CMS marking stack overflow (benign) at " | |
| 7563 SIZE_FORMAT, _markStack->capacity()); | |
| 7564 } | |
| 7565 assert(simulate_overflow || _markStack->isFull(), "Else push should have succeeded"); | |
| 7566 handle_stack_overflow(addr); | |
| 7567 } | |
| 7568 } | |
| 7569 // anything including and to the right of _finger | |
| 7570 // will be scanned as we iterate over the remainder of the | |
| 7571 // bit map | |
| 7572 do_yield_check(); | |
| 7573 } | |
| 7574 } | |
| 7575 | |
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7576 void PushOrMarkClosure::do_oop(oop* p) { PushOrMarkClosure::do_oop_work(p); } |
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7577 void PushOrMarkClosure::do_oop(narrowOop* p) { PushOrMarkClosure::do_oop_work(p); } |
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7578 |
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7579 void Par_PushOrMarkClosure::do_oop(oop obj) { |
| 0 | 7580 // Ignore mark word because we are running concurrent with mutators. |
|
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7581 assert(obj->is_oop_or_null(true), "expected an oop or NULL"); |
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7582 HeapWord* addr = (HeapWord*)obj; |
| 0 | 7583 if (_whole_span.contains(addr) && !_bit_map->isMarked(addr)) { |
| 7584 // Oop lies in _span and isn't yet grey or black | |
| 7585 // We read the global_finger (volatile read) strictly after marking oop | |
| 7586 bool res = _bit_map->par_mark(addr); // now grey | |
| 7587 volatile HeapWord** gfa = (volatile HeapWord**)_global_finger_addr; | |
| 7588 // Should we push this marked oop on our stack? | |
| 7589 // -- if someone else marked it, nothing to do | |
| 7590 // -- if target oop is above global finger nothing to do | |
| 7591 // -- if target oop is in chunk and above local finger | |
| 7592 // then nothing to do | |
| 7593 // -- else push on work queue | |
| 7594 if ( !res // someone else marked it, they will deal with it | |
| 7595 || (addr >= *gfa) // will be scanned in a later task | |
| 7596 || (_span.contains(addr) && addr >= _finger)) { // later in this chunk | |
| 7597 return; | |
| 7598 } | |
| 7599 // the bit map iteration has already either passed, or | |
| 7600 // sampled, this bit in the bit map; we'll need to | |
| 7601 // use the marking stack to scan this oop's oops. | |
| 7602 bool simulate_overflow = false; | |
| 7603 NOT_PRODUCT( | |
| 7604 if (CMSMarkStackOverflowALot && | |
| 7605 _collector->simulate_overflow()) { | |
| 7606 // simulate a stack overflow | |
| 7607 simulate_overflow = true; | |
| 7608 } | |
| 7609 ) | |
| 7610 if (simulate_overflow || | |
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7611 !(_work_queue->push(obj) || _overflow_stack->par_push(obj))) { |
| 0 | 7612 // stack overflow |
| 7613 if (PrintCMSStatistics != 0) { | |
| 7614 gclog_or_tty->print_cr("CMS marking stack overflow (benign) at " | |
| 7615 SIZE_FORMAT, _overflow_stack->capacity()); | |
| 7616 } | |
| 7617 // We cannot assert that the overflow stack is full because | |
| 7618 // it may have been emptied since. | |
| 7619 assert(simulate_overflow || | |
| 7620 _work_queue->size() == _work_queue->max_elems(), | |
| 7621 "Else push should have succeeded"); | |
| 7622 handle_stack_overflow(addr); | |
| 7623 } | |
| 7624 do_yield_check(); | |
| 7625 } | |
| 7626 } | |
| 7627 | |
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7628 void Par_PushOrMarkClosure::do_oop(oop* p) { Par_PushOrMarkClosure::do_oop_work(p); } |
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7629 void Par_PushOrMarkClosure::do_oop(narrowOop* p) { Par_PushOrMarkClosure::do_oop_work(p); } |
| 0 | 7630 |
| 7631 PushAndMarkClosure::PushAndMarkClosure(CMSCollector* collector, | |
| 7632 MemRegion span, | |
| 7633 ReferenceProcessor* rp, | |
| 7634 CMSBitMap* bit_map, | |
| 7635 CMSBitMap* mod_union_table, | |
| 7636 CMSMarkStack* mark_stack, | |
| 7637 bool concurrent_precleaning): | |
|
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7638 CMSOopClosure(rp), |
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7639 _collector(collector), |
| 0 | 7640 _span(span), |
| 7641 _bit_map(bit_map), | |
| 7642 _mod_union_table(mod_union_table), | |
| 7643 _mark_stack(mark_stack), | |
| 935 | 7644 _concurrent_precleaning(concurrent_precleaning) |
| 0 | 7645 { |
| 7646 assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL"); | |
| 7647 } | |
| 7648 | |
| 7649 // Grey object rescan during pre-cleaning and second checkpoint phases -- | |
| 7650 // the non-parallel version (the parallel version appears further below.) | |
|
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7651 void PushAndMarkClosure::do_oop(oop obj) { |
|
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7652 // Ignore mark word verification. If during concurrent precleaning, |
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7653 // the object monitor may be locked. If during the checkpoint |
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7654 // phases, the object may already have been reached by a different |
|
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7655 // path and may be at the end of the global overflow list (so |
|
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7656 // the mark word may be NULL). |
|
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7657 assert(obj->is_oop_or_null(true /* ignore mark word */), |
| 0 | 7658 "expected an oop or NULL"); |
|
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7659 HeapWord* addr = (HeapWord*)obj; |
| 0 | 7660 // Check if oop points into the CMS generation |
| 7661 // and is not marked | |
| 7662 if (_span.contains(addr) && !_bit_map->isMarked(addr)) { | |
| 7663 // a white object ... | |
| 7664 _bit_map->mark(addr); // ... now grey | |
| 7665 // push on the marking stack (grey set) | |
| 7666 bool simulate_overflow = false; | |
| 7667 NOT_PRODUCT( | |
| 7668 if (CMSMarkStackOverflowALot && | |
| 7669 _collector->simulate_overflow()) { | |
| 7670 // simulate a stack overflow | |
| 7671 simulate_overflow = true; | |
| 7672 } | |
| 7673 ) | |
|
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7674 if (simulate_overflow || !_mark_stack->push(obj)) { |
| 0 | 7675 if (_concurrent_precleaning) { |
|
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7676 // During precleaning we can just dirty the appropriate card(s) |
| 0 | 7677 // in the mod union table, thus ensuring that the object remains |
|
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7678 // in the grey set and continue. In the case of object arrays |
|
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7679 // we need to dirty all of the cards that the object spans, |
|
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7680 // since the rescan of object arrays will be limited to the |
|
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7681 // dirty cards. |
|
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7682 // Note that no one can be intefering with us in this action |
|
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7683 // of dirtying the mod union table, so no locking or atomics |
|
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7684 // are required. |
|
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|
7685 if (obj->is_objArray()) { |
|
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7686 size_t sz = obj->size(); |
|
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7687 HeapWord* end_card_addr = (HeapWord*)round_to( |
|
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|
7688 (intptr_t)(addr+sz), CardTableModRefBS::card_size); |
|
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|
7689 MemRegion redirty_range = MemRegion(addr, end_card_addr); |
|
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|
7690 assert(!redirty_range.is_empty(), "Arithmetical tautology"); |
|
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7691 _mod_union_table->mark_range(redirty_range); |
|
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|
7692 } else { |
|
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|
7693 _mod_union_table->mark(addr); |
|
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7694 } |
| 0 | 7695 _collector->_ser_pmc_preclean_ovflw++; |
| 7696 } else { | |
| 7697 // During the remark phase, we need to remember this oop | |
| 7698 // in the overflow list. | |
|
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7699 _collector->push_on_overflow_list(obj); |
| 0 | 7700 _collector->_ser_pmc_remark_ovflw++; |
| 7701 } | |
| 7702 } | |
| 7703 } | |
| 7704 } | |
| 7705 | |
| 7706 Par_PushAndMarkClosure::Par_PushAndMarkClosure(CMSCollector* collector, | |
| 7707 MemRegion span, | |
| 7708 ReferenceProcessor* rp, | |
| 7709 CMSBitMap* bit_map, | |
|
6725
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7710 OopTaskQueue* work_queue): |
|
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7711 CMSOopClosure(rp), |
|
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7712 _collector(collector), |
| 0 | 7713 _span(span), |
| 7714 _bit_map(bit_map), | |
| 935 | 7715 _work_queue(work_queue) |
| 0 | 7716 { |
| 7717 assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL"); | |
| 7718 } | |
| 7719 | |
|
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7720 void PushAndMarkClosure::do_oop(oop* p) { PushAndMarkClosure::do_oop_work(p); } |
|
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7721 void PushAndMarkClosure::do_oop(narrowOop* p) { PushAndMarkClosure::do_oop_work(p); } |
|
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7722 |
| 0 | 7723 // Grey object rescan during second checkpoint phase -- |
| 7724 // the parallel version. | |
|
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7725 void Par_PushAndMarkClosure::do_oop(oop obj) { |
| 0 | 7726 // In the assert below, we ignore the mark word because |
| 7727 // this oop may point to an already visited object that is | |
| 7728 // on the overflow stack (in which case the mark word has | |
| 7729 // been hijacked for chaining into the overflow stack -- | |
| 7730 // if this is the last object in the overflow stack then | |
| 7731 // its mark word will be NULL). Because this object may | |
| 7732 // have been subsequently popped off the global overflow | |
| 7733 // stack, and the mark word possibly restored to the prototypical | |
| 7734 // value, by the time we get to examined this failing assert in | |
| 7735 // the debugger, is_oop_or_null(false) may subsequently start | |
| 7736 // to hold. | |
|
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|
7737 assert(obj->is_oop_or_null(true), |
| 0 | 7738 "expected an oop or NULL"); |
|
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7739 HeapWord* addr = (HeapWord*)obj; |
| 0 | 7740 // Check if oop points into the CMS generation |
| 7741 // and is not marked | |
| 7742 if (_span.contains(addr) && !_bit_map->isMarked(addr)) { | |
| 7743 // a white object ... | |
| 7744 // If we manage to "claim" the object, by being the | |
| 7745 // first thread to mark it, then we push it on our | |
| 7746 // marking stack | |
| 7747 if (_bit_map->par_mark(addr)) { // ... now grey | |
| 7748 // push on work queue (grey set) | |
| 7749 bool simulate_overflow = false; | |
| 7750 NOT_PRODUCT( | |
| 7751 if (CMSMarkStackOverflowALot && | |
| 7752 _collector->par_simulate_overflow()) { | |
| 7753 // simulate a stack overflow | |
| 7754 simulate_overflow = true; | |
| 7755 } | |
| 7756 ) | |
|
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7757 if (simulate_overflow || !_work_queue->push(obj)) { |
|
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|
7758 _collector->par_push_on_overflow_list(obj); |
| 0 | 7759 _collector->_par_pmc_remark_ovflw++; // imprecise OK: no need to CAS |
| 7760 } | |
| 7761 } // Else, some other thread got there first | |
| 7762 } | |
| 7763 } | |
| 7764 | |
|
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7765 void Par_PushAndMarkClosure::do_oop(oop* p) { Par_PushAndMarkClosure::do_oop_work(p); } |
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7766 void Par_PushAndMarkClosure::do_oop(narrowOop* p) { Par_PushAndMarkClosure::do_oop_work(p); } |
|
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7767 |
| 0 | 7768 void CMSPrecleanRefsYieldClosure::do_yield_work() { |
| 7769 Mutex* bml = _collector->bitMapLock(); | |
| 7770 assert_lock_strong(bml); | |
| 7771 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 7772 "CMS thread should hold CMS token"); | |
| 7773 | |
| 7774 bml->unlock(); | |
| 7775 ConcurrentMarkSweepThread::desynchronize(true); | |
| 7776 | |
| 7777 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7778 | |
| 7779 _collector->stopTimer(); | |
| 7780 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 7781 if (PrintCMSStatistics != 0) { | |
| 7782 _collector->incrementYields(); | |
| 7783 } | |
| 7784 _collector->icms_wait(); | |
| 7785 | |
| 7786 // See the comment in coordinator_yield() | |
| 7787 for (unsigned i = 0; i < CMSYieldSleepCount && | |
| 7788 ConcurrentMarkSweepThread::should_yield() && | |
| 7789 !CMSCollector::foregroundGCIsActive(); ++i) { | |
| 7790 os::sleep(Thread::current(), 1, false); | |
| 7791 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 7792 } | |
| 7793 | |
| 7794 ConcurrentMarkSweepThread::synchronize(true); | |
| 7795 bml->lock(); | |
| 7796 | |
| 7797 _collector->startTimer(); | |
| 7798 } | |
| 7799 | |
| 7800 bool CMSPrecleanRefsYieldClosure::should_return() { | |
| 7801 if (ConcurrentMarkSweepThread::should_yield()) { | |
| 7802 do_yield_work(); | |
| 7803 } | |
| 7804 return _collector->foregroundGCIsActive(); | |
| 7805 } | |
| 7806 | |
| 7807 void MarkFromDirtyCardsClosure::do_MemRegion(MemRegion mr) { | |
| 7808 assert(((size_t)mr.start())%CardTableModRefBS::card_size_in_words == 0, | |
| 7809 "mr should be aligned to start at a card boundary"); | |
| 7810 // We'd like to assert: | |
| 7811 // assert(mr.word_size()%CardTableModRefBS::card_size_in_words == 0, | |
| 7812 // "mr should be a range of cards"); | |
| 7813 // However, that would be too strong in one case -- the last | |
| 7814 // partition ends at _unallocated_block which, in general, can be | |
| 7815 // an arbitrary boundary, not necessarily card aligned. | |
| 7816 if (PrintCMSStatistics != 0) { | |
| 7817 _num_dirty_cards += | |
| 7818 mr.word_size()/CardTableModRefBS::card_size_in_words; | |
| 7819 } | |
| 7820 _space->object_iterate_mem(mr, &_scan_cl); | |
| 7821 } | |
| 7822 | |
| 7823 SweepClosure::SweepClosure(CMSCollector* collector, | |
| 7824 ConcurrentMarkSweepGeneration* g, | |
| 7825 CMSBitMap* bitMap, bool should_yield) : | |
| 7826 _collector(collector), | |
| 7827 _g(g), | |
| 7828 _sp(g->cmsSpace()), | |
| 7829 _limit(_sp->sweep_limit()), | |
| 7830 _freelistLock(_sp->freelistLock()), | |
| 7831 _bitMap(bitMap), | |
| 7832 _yield(should_yield), | |
| 7833 _inFreeRange(false), // No free range at beginning of sweep | |
| 7834 _freeRangeInFreeLists(false), // No free range at beginning of sweep | |
| 7835 _lastFreeRangeCoalesced(false), | |
| 7836 _freeFinger(g->used_region().start()) | |
| 7837 { | |
| 7838 NOT_PRODUCT( | |
| 7839 _numObjectsFreed = 0; | |
| 7840 _numWordsFreed = 0; | |
| 7841 _numObjectsLive = 0; | |
| 7842 _numWordsLive = 0; | |
| 7843 _numObjectsAlreadyFree = 0; | |
| 7844 _numWordsAlreadyFree = 0; | |
| 7845 _last_fc = NULL; | |
| 7846 | |
| 7847 _sp->initializeIndexedFreeListArrayReturnedBytes(); | |
|
6028
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|
7848 _sp->dictionary()->initialize_dict_returned_bytes(); |
| 0 | 7849 ) |
| 7850 assert(_limit >= _sp->bottom() && _limit <= _sp->end(), | |
| 7851 "sweep _limit out of bounds"); | |
| 7852 if (CMSTraceSweeper) { | |
|
3746
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|
7853 gclog_or_tty->print_cr("\n====================\nStarting new sweep with limit " PTR_FORMAT, |
|
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|
7854 _limit); |
|
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|
7855 } |
|
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|
7856 } |
|
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|
7857 |
|
537a4053b0f9
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|
7858 void SweepClosure::print_on(outputStream* st) const { |
|
537a4053b0f9
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|
7859 tty->print_cr("_sp = [" PTR_FORMAT "," PTR_FORMAT ")", |
|
537a4053b0f9
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|
7860 _sp->bottom(), _sp->end()); |
|
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|
7861 tty->print_cr("_limit = " PTR_FORMAT, _limit); |
|
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|
7862 tty->print_cr("_freeFinger = " PTR_FORMAT, _freeFinger); |
|
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|
7863 NOT_PRODUCT(tty->print_cr("_last_fc = " PTR_FORMAT, _last_fc);) |
|
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|
7864 tty->print_cr("_inFreeRange = %d, _freeRangeInFreeLists = %d, _lastFreeRangeCoalesced = %d", |
|
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|
7865 _inFreeRange, _freeRangeInFreeLists, _lastFreeRangeCoalesced); |
|
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|
7866 } |
|
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|
7867 |
|
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|
7868 #ifndef PRODUCT |
|
537a4053b0f9
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|
7869 // Assertion checking only: no useful work in product mode -- |
|
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|
7870 // however, if any of the flags below become product flags, |
|
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|
7871 // you may need to review this code to see if it needs to be |
|
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|
7872 // enabled in product mode. |
| 0 | 7873 SweepClosure::~SweepClosure() { |
| 7874 assert_lock_strong(_freelistLock); | |
|
2132
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|
7875 assert(_limit >= _sp->bottom() && _limit <= _sp->end(), |
|
4947ee68d19c
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|
7876 "sweep _limit out of bounds"); |
| 0 | 7877 if (inFreeRange()) { |
|
3746
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|
7878 warning("inFreeRange() should have been reset; dumping state of SweepClosure"); |
|
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|
7879 print(); |
|
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|
7880 ShouldNotReachHere(); |
|
537a4053b0f9
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|
7881 } |
|
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|
7882 if (Verbose && PrintGC) { |
|
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|
7883 gclog_or_tty->print("Collected "SIZE_FORMAT" objects, " SIZE_FORMAT " bytes", |
|
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|
7884 _numObjectsFreed, _numWordsFreed*sizeof(HeapWord)); |
|
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|
7885 gclog_or_tty->print_cr("\nLive "SIZE_FORMAT" objects, " |
|
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|
7886 SIZE_FORMAT" bytes " |
|
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|
7887 "Already free "SIZE_FORMAT" objects, "SIZE_FORMAT" bytes", |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
7888 _numObjectsLive, _numWordsLive*sizeof(HeapWord), |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
7889 _numObjectsAlreadyFree, _numWordsAlreadyFree*sizeof(HeapWord)); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
7890 size_t totalBytes = (_numWordsFreed + _numWordsLive + _numWordsAlreadyFree) |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
7891 * sizeof(HeapWord); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
7892 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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|
7893 |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
7894 if (PrintCMSStatistics && CMSVerifyReturnedBytes) { |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
7895 size_t indexListReturnedBytes = _sp->sumIndexedFreeListArrayReturnedBytes(); |
|
6028
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7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
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|
7896 size_t dict_returned_bytes = _sp->dictionary()->sum_dict_returned_bytes(); |
|
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
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|
7897 size_t returned_bytes = indexListReturnedBytes + dict_returned_bytes; |
|
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
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6026
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|
7898 gclog_or_tty->print("Returned "SIZE_FORMAT" bytes", returned_bytes); |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
7899 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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|
7900 indexListReturnedBytes); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
7901 gclog_or_tty->print_cr(" Dictionary Returned "SIZE_FORMAT" bytes", |
|
6028
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
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6026
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|
7902 dict_returned_bytes); |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
7903 } |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
7904 } |
| 0 | 7905 if (CMSTraceSweeper) { |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
7906 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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|
7907 _limit); |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
7908 } |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
7909 } |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
7910 #endif // PRODUCT |
| 0 | 7911 |
| 7912 void SweepClosure::initialize_free_range(HeapWord* freeFinger, | |
| 7913 bool freeRangeInFreeLists) { | |
| 7914 if (CMSTraceSweeper) { | |
|
2132
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7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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|
7915 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
|
7916 freeFinger, freeRangeInFreeLists); |
| 0 | 7917 } |
| 7918 assert(!inFreeRange(), "Trampling existing free range"); | |
| 7919 set_inFreeRange(true); | |
| 7920 set_lastFreeRangeCoalesced(false); | |
| 7921 | |
| 7922 set_freeFinger(freeFinger); | |
| 7923 set_freeRangeInFreeLists(freeRangeInFreeLists); | |
| 7924 if (CMSTestInFreeList) { | |
| 7925 if (freeRangeInFreeLists) { | |
| 7926 FreeChunk* fc = (FreeChunk*) freeFinger; | |
|
6028
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7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
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|
7927 assert(fc->is_free(), "A chunk on the free list should be free."); |
| 0 | 7928 assert(fc->size() > 0, "Free range should have a size"); |
|
6028
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jmasa
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|
7929 assert(_sp->verify_chunk_in_free_list(fc), "Chunk is not in free lists"); |
| 0 | 7930 } |
| 7931 } | |
| 7932 } | |
| 7933 | |
| 7934 // Note that the sweeper runs concurrently with mutators. Thus, | |
| 7935 // it is possible for direct allocation in this generation to happen | |
| 7936 // in the middle of the sweep. Note that the sweeper also coalesces | |
| 7937 // contiguous free blocks. Thus, unless the sweeper and the allocator | |
| 7938 // synchronize appropriately freshly allocated blocks may get swept up. | |
| 7939 // This is accomplished by the sweeper locking the free lists while | |
| 7940 // it is sweeping. Thus blocks that are determined to be free are | |
| 7941 // indeed free. There is however one additional complication: | |
| 7942 // blocks that have been allocated since the final checkpoint and | |
| 7943 // mark, will not have been marked and so would be treated as | |
| 7944 // unreachable and swept up. To prevent this, the allocator marks | |
| 7945 // the bit map when allocating during the sweep phase. This leads, | |
| 7946 // however, to a further complication -- objects may have been allocated | |
| 7947 // but not yet initialized -- in the sense that the header isn't yet | |
| 7948 // installed. The sweeper can not then determine the size of the block | |
| 7949 // in order to skip over it. To deal with this case, we use a technique | |
| 7950 // (due to Printezis) to encode such uninitialized block sizes in the | |
| 7951 // bit map. Since the bit map uses a bit per every HeapWord, but the | |
| 7952 // CMS generation has a minimum object size of 3 HeapWords, it follows | |
| 7953 // that "normal marks" won't be adjacent in the bit map (there will | |
| 7954 // always be at least two 0 bits between successive 1 bits). We make use | |
| 7955 // of these "unused" bits to represent uninitialized blocks -- the bit | |
| 7956 // corresponding to the start of the uninitialized object and the next | |
| 7957 // bit are both set. Finally, a 1 bit marks the end of the object that | |
| 7958 // started with the two consecutive 1 bits to indicate its potentially | |
| 7959 // uninitialized state. | |
| 7960 | |
| 7961 size_t SweepClosure::do_blk_careful(HeapWord* addr) { | |
| 7962 FreeChunk* fc = (FreeChunk*)addr; | |
| 7963 size_t res; | |
| 7964 | |
|
1720
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
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1716
diff
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|
7965 // 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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|
7966 // 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
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|
7967 // we started the sweep, it may no longer be one because heap expansion |
|
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
parents:
1716
diff
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|
7968 // may have caused us to coalesce the block ending at the address _limit |
|
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
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1716
diff
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|
7969 // 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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3356
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changeset
|
7970 // 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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|
7971 // see the following Zeno-like trail of CRs 6977970, 7008136, 7042740. |
|
2132
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7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
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|
7972 if (addr >= _limit) { // we have swept up to or past the limit: finish up |
| 0 | 7973 assert(_limit >= _sp->bottom() && _limit <= _sp->end(), |
| 7974 "sweep _limit out of bounds"); | |
|
1720
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
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1716
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|
7975 assert(addr < _sp->end(), "addr out of bounds"); |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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3356
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|
7976 // 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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|
7977 // coalesced chunk to the appropriate free list. |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
changeset
|
7978 if (inFreeRange()) { |
|
3746
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7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
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|
7979 assert(freeFinger() >= _sp->bottom() && freeFinger() < _limit, |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
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|
7980 err_msg("freeFinger() " PTR_FORMAT" is out-of-bounds", freeFinger())); |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
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|
7981 flush_cur_free_chunk(freeFinger(), |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
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|
7982 pointer_delta(addr, freeFinger())); |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
changeset
|
7983 if (CMSTraceSweeper) { |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
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|
7984 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
|
7985 gclog_or_tty->print("put_free_blk 0x%x ("SIZE_FORMAT") " |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
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|
7986 "[coalesced:"SIZE_FORMAT"]\n", |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
7987 freeFinger(), pointer_delta(addr, freeFinger()), |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
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|
7988 lastFreeRangeCoalesced()); |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
7989 } |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
7990 } |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
7991 |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
7992 // help the iterator loop finish |
|
1720
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
parents:
1716
diff
changeset
|
7993 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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|
7994 } |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
changeset
|
7995 |
|
1720
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
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1716
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|
7996 assert(addr < _limit, "sweep invariant"); |
| 0 | 7997 // check if we should yield |
| 7998 do_yield_check(addr); | |
|
6028
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jmasa
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|
7999 if (fc->is_free()) { |
| 0 | 8000 // Chunk that is already free |
| 8001 res = fc->size(); | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
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|
8002 do_already_free_chunk(fc); |
| 0 | 8003 debug_only(_sp->verifyFreeLists()); |
|
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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3356
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|
8004 // If we flush the chunk at hand in lookahead_and_flush() |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
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|
8005 // and it's coalesced with a preceding chunk, then the |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
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|
8006 // process of "mangling" the payload of the coalesced block |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
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|
8007 // will cause erasure of the size information from the |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
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|
8008 // (erstwhile) header of all the coalesced blocks but the |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
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|
8009 // first, so the first disjunct in the assert will not hold |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
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|
8010 // in that specific case (in which case the second disjunct |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
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|
8011 // will hold). |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
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|
8012 assert(res == fc->size() || ((HeapWord*)fc) + res >= _limit, |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
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|
8013 "Otherwise the size info doesn't change at this step"); |
| 0 | 8014 NOT_PRODUCT( |
| 8015 _numObjectsAlreadyFree++; | |
| 8016 _numWordsAlreadyFree += res; | |
| 8017 ) | |
| 8018 NOT_PRODUCT(_last_fc = fc;) | |
| 8019 } else if (!_bitMap->isMarked(addr)) { | |
| 8020 // Chunk is fresh garbage | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8021 res = do_garbage_chunk(fc); |
| 0 | 8022 debug_only(_sp->verifyFreeLists()); |
| 8023 NOT_PRODUCT( | |
| 8024 _numObjectsFreed++; | |
| 8025 _numWordsFreed += res; | |
| 8026 ) | |
| 8027 } else { | |
| 8028 // Chunk that is alive. | |
|
2132
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7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
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|
8029 res = do_live_chunk(fc); |
| 0 | 8030 debug_only(_sp->verifyFreeLists()); |
| 8031 NOT_PRODUCT( | |
| 8032 _numObjectsLive++; | |
| 8033 _numWordsLive += res; | |
| 8034 ) | |
| 8035 } | |
| 8036 return res; | |
| 8037 } | |
| 8038 | |
| 8039 // For the smart allocation, record following | |
| 8040 // split deaths - a free chunk is removed from its free list because | |
| 8041 // it is being split into two or more chunks. | |
| 8042 // split birth - a free chunk is being added to its free list because | |
| 8043 // a larger free chunk has been split and resulted in this free chunk. | |
| 8044 // coal death - a free chunk is being removed from its free list because | |
| 8045 // it is being coalesced into a large free chunk. | |
| 8046 // coal birth - a free chunk is being added to its free list because | |
| 8047 // it was created when two or more free chunks where coalesced into | |
| 8048 // this free chunk. | |
| 8049 // | |
| 8050 // These statistics are used to determine the desired number of free | |
| 8051 // chunks of a given size. The desired number is chosen to be relative | |
| 8052 // to the end of a CMS sweep. The desired number at the end of a sweep | |
| 8053 // is the | |
| 8054 // count-at-end-of-previous-sweep (an amount that was enough) | |
| 8055 // - count-at-beginning-of-current-sweep (the excess) | |
| 8056 // + split-births (gains in this size during interval) | |
| 8057 // - split-deaths (demands on this size during interval) | |
| 8058 // where the interval is from the end of one sweep to the end of the | |
| 8059 // next. | |
| 8060 // | |
| 8061 // When sweeping the sweeper maintains an accumulated chunk which is | |
| 8062 // the chunk that is made up of chunks that have been coalesced. That | |
| 8063 // will be termed the left-hand chunk. A new chunk of garbage that | |
| 8064 // is being considered for coalescing will be referred to as the | |
| 8065 // right-hand chunk. | |
| 8066 // | |
| 8067 // When making a decision on whether to coalesce a right-hand chunk with | |
| 8068 // the current left-hand chunk, the current count vs. the desired count | |
| 8069 // of the left-hand chunk is considered. Also if the right-hand chunk | |
| 8070 // is near the large chunk at the end of the heap (see | |
| 8071 // ConcurrentMarkSweepGeneration::isNearLargestChunk()), then the | |
| 8072 // left-hand chunk is coalesced. | |
| 8073 // | |
| 8074 // When making a decision about whether to split a chunk, the desired count | |
| 8075 // vs. the current count of the candidate to be split is also considered. | |
| 8076 // If the candidate is underpopulated (currently fewer chunks than desired) | |
| 8077 // a chunk of an overpopulated (currently more chunks than desired) size may | |
| 8078 // be chosen. The "hint" associated with a free list, if non-null, points | |
| 8079 // to a free list which may be overpopulated. | |
| 8080 // | |
| 8081 | |
|
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8082 void SweepClosure::do_already_free_chunk(FreeChunk* fc) { |
|
3746
537a4053b0f9
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ysr
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3356
diff
changeset
|
8083 const size_t size = fc->size(); |
| 0 | 8084 // Chunks that cannot be coalesced are not in the |
| 8085 // free lists. | |
| 8086 if (CMSTestInFreeList && !fc->cantCoalesce()) { | |
|
6028
f69a5d43dc19
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jmasa
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6026
diff
changeset
|
8087 assert(_sp->verify_chunk_in_free_list(fc), |
| 0 | 8088 "free chunk should be in free lists"); |
| 8089 } | |
| 8090 // a chunk that is already free, should not have been | |
| 8091 // marked in the bit map | |
|
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|
8092 HeapWord* const addr = (HeapWord*) fc; |
| 0 | 8093 assert(!_bitMap->isMarked(addr), "free chunk should be unmarked"); |
| 8094 // Verify that the bit map has no bits marked between | |
| 8095 // addr and purported end of this block. | |
| 8096 _bitMap->verifyNoOneBitsInRange(addr + 1, addr + size); | |
| 8097 | |
|
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|
8098 // Some chunks cannot be coalesced under any circumstances. |
| 0 | 8099 // See the definition of cantCoalesce(). |
| 8100 if (!fc->cantCoalesce()) { | |
| 8101 // This chunk can potentially be coalesced. | |
| 8102 if (_sp->adaptive_freelists()) { | |
| 8103 // All the work is done in | |
|
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|
8104 do_post_free_or_garbage_chunk(fc, size); |
| 0 | 8105 } else { // Not adaptive free lists |
| 8106 // this is a free chunk that can potentially be coalesced by the sweeper; | |
| 8107 if (!inFreeRange()) { | |
| 8108 // if the next chunk is a free block that can't be coalesced | |
| 8109 // it doesn't make sense to remove this chunk from the free lists | |
| 8110 FreeChunk* nextChunk = (FreeChunk*)(addr + size); | |
|
2136
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|
8111 assert((HeapWord*)nextChunk <= _sp->end(), "Chunk size out of bounds?"); |
|
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|
8112 if ((HeapWord*)nextChunk < _sp->end() && // There is another free chunk to the right ... |
|
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|
8113 nextChunk->is_free() && // ... which is free... |
|
2136
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|
8114 nextChunk->cantCoalesce()) { // ... but can't be coalesced |
| 0 | 8115 // nothing to do |
| 8116 } else { | |
| 8117 // Potentially the start of a new free range: | |
| 8118 // Don't eagerly remove it from the free lists. | |
| 8119 // No need to remove it if it will just be put | |
| 8120 // back again. (Also from a pragmatic point of view | |
| 8121 // if it is a free block in a region that is beyond | |
| 8122 // any allocated blocks, an assertion will fail) | |
| 8123 // Remember the start of a free run. | |
| 8124 initialize_free_range(addr, true); | |
| 8125 // end - can coalesce with next chunk | |
| 8126 } | |
| 8127 } else { | |
| 8128 // the midst of a free range, we are coalescing | |
|
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|
8129 print_free_block_coalesced(fc); |
| 0 | 8130 if (CMSTraceSweeper) { |
| 8131 gclog_or_tty->print(" -- pick up free block 0x%x (%d)\n", fc, size); | |
| 8132 } | |
| 8133 // remove it from the free lists | |
| 8134 _sp->removeFreeChunkFromFreeLists(fc); | |
| 8135 set_lastFreeRangeCoalesced(true); | |
| 8136 // If the chunk is being coalesced and the current free range is | |
| 8137 // in the free lists, remove the current free range so that it | |
| 8138 // will be returned to the free lists in its entirety - all | |
| 8139 // the coalesced pieces included. | |
| 8140 if (freeRangeInFreeLists()) { | |
| 8141 FreeChunk* ffc = (FreeChunk*) freeFinger(); | |
| 8142 assert(ffc->size() == pointer_delta(addr, freeFinger()), | |
| 8143 "Size of free range is inconsistent with chunk size."); | |
| 8144 if (CMSTestInFreeList) { | |
|
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|
8145 assert(_sp->verify_chunk_in_free_list(ffc), |
| 0 | 8146 "free range is not in free lists"); |
| 8147 } | |
| 8148 _sp->removeFreeChunkFromFreeLists(ffc); | |
| 8149 set_freeRangeInFreeLists(false); | |
| 8150 } | |
| 8151 } | |
| 8152 } | |
|
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|
8153 // Note that if the chunk is not coalescable (the else arm |
|
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|
8154 // below), we unconditionally flush, without needing to do |
|
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|
8155 // a "lookahead," as we do below. |
|
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|
8156 if (inFreeRange()) lookahead_and_flush(fc, size); |
| 0 | 8157 } else { |
| 8158 // Code path common to both original and adaptive free lists. | |
| 8159 | |
| 8160 // cant coalesce with previous block; this should be treated | |
| 8161 // as the end of a free run if any | |
| 8162 if (inFreeRange()) { | |
| 8163 // we kicked some butt; time to pick up the garbage | |
|
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|
8164 assert(freeFinger() < addr, "freeFinger points too high"); |
|
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changeset
|
8165 flush_cur_free_chunk(freeFinger(), pointer_delta(addr, freeFinger())); |
| 0 | 8166 } |
| 8167 // else, nothing to do, just continue | |
| 8168 } | |
| 8169 } | |
| 8170 | |
|
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|
8171 size_t SweepClosure::do_garbage_chunk(FreeChunk* fc) { |
| 0 | 8172 // This is a chunk of garbage. It is not in any free list. |
| 8173 // Add it to a free list or let it possibly be coalesced into | |
| 8174 // a larger chunk. | |
|
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|
8175 HeapWord* const addr = (HeapWord*) fc; |
|
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|
8176 const size_t size = CompactibleFreeListSpace::adjustObjectSize(oop(addr)->size()); |
| 0 | 8177 |
| 8178 if (_sp->adaptive_freelists()) { | |
| 8179 // Verify that the bit map has no bits marked between | |
| 8180 // addr and purported end of just dead object. | |
| 8181 _bitMap->verifyNoOneBitsInRange(addr + 1, addr + size); | |
| 8182 | |
|
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diff
changeset
|
8183 do_post_free_or_garbage_chunk(fc, size); |
| 0 | 8184 } else { |
| 8185 if (!inFreeRange()) { | |
| 8186 // start of a new free range | |
| 8187 assert(size > 0, "A free range should have a size"); | |
| 8188 initialize_free_range(addr, false); | |
| 8189 } else { | |
| 8190 // this will be swept up when we hit the end of the | |
| 8191 // free range | |
| 8192 if (CMSTraceSweeper) { | |
| 8193 gclog_or_tty->print(" -- pick up garbage 0x%x (%d) \n", fc, size); | |
| 8194 } | |
| 8195 // If the chunk is being coalesced and the current free range is | |
| 8196 // in the free lists, remove the current free range so that it | |
| 8197 // will be returned to the free lists in its entirety - all | |
| 8198 // the coalesced pieces included. | |
| 8199 if (freeRangeInFreeLists()) { | |
| 8200 FreeChunk* ffc = (FreeChunk*)freeFinger(); | |
| 8201 assert(ffc->size() == pointer_delta(addr, freeFinger()), | |
| 8202 "Size of free range is inconsistent with chunk size."); | |
| 8203 if (CMSTestInFreeList) { | |
|
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|
8204 assert(_sp->verify_chunk_in_free_list(ffc), |
| 0 | 8205 "free range is not in free lists"); |
| 8206 } | |
| 8207 _sp->removeFreeChunkFromFreeLists(ffc); | |
| 8208 set_freeRangeInFreeLists(false); | |
| 8209 } | |
| 8210 set_lastFreeRangeCoalesced(true); | |
| 8211 } | |
| 8212 // this will be swept up when we hit the end of the free range | |
| 8213 | |
| 8214 // Verify that the bit map has no bits marked between | |
| 8215 // addr and purported end of just dead object. | |
| 8216 _bitMap->verifyNoOneBitsInRange(addr + 1, addr + size); | |
| 8217 } | |
|
3746
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|
8218 assert(_limit >= addr + size, |
|
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|
8219 "A freshly garbage chunk can't possibly straddle over _limit"); |
|
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changeset
|
8220 if (inFreeRange()) lookahead_and_flush(fc, size); |
| 0 | 8221 return size; |
| 8222 } | |
| 8223 | |
|
2132
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|
8224 size_t SweepClosure::do_live_chunk(FreeChunk* fc) { |
| 0 | 8225 HeapWord* addr = (HeapWord*) fc; |
| 8226 // The sweeper has just found a live object. Return any accumulated | |
| 8227 // left hand chunk to the free lists. | |
| 8228 if (inFreeRange()) { | |
|
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diff
changeset
|
8229 assert(freeFinger() < addr, "freeFinger points too high"); |
|
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7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
changeset
|
8230 flush_cur_free_chunk(freeFinger(), pointer_delta(addr, freeFinger())); |
|
4947ee68d19c
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1994
diff
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|
8231 } |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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diff
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|
8232 |
|
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changeset
|
8233 // This object is live: we'd normally expect this to be |
| 0 | 8234 // an oop, and like to assert the following: |
| 8235 // assert(oop(addr)->is_oop(), "live block should be an oop"); | |
| 8236 // However, as we commented above, this may be an object whose | |
| 8237 // header hasn't yet been initialized. | |
| 8238 size_t size; | |
| 8239 assert(_bitMap->isMarked(addr), "Tautology for this control point"); | |
| 8240 if (_bitMap->isMarked(addr + 1)) { | |
| 8241 // Determine the size from the bit map, rather than trying to | |
| 8242 // compute it from the object header. | |
| 8243 HeapWord* nextOneAddr = _bitMap->getNextMarkedWordAddress(addr + 2); | |
| 8244 size = pointer_delta(nextOneAddr + 1, addr); | |
| 8245 assert(size == CompactibleFreeListSpace::adjustObjectSize(size), | |
| 8246 "alignment problem"); | |
| 8247 | |
|
2132
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1994
diff
changeset
|
8248 #ifdef DEBUG |
|
6725
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
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|
8249 if (oop(addr)->klass_or_null() != NULL) { |
| 0 | 8250 // Ignore mark word because we are running concurrent with mutators |
| 8251 assert(oop(addr)->is_oop(true), "live block should be an oop"); | |
| 8252 assert(size == | |
| 8253 CompactibleFreeListSpace::adjustObjectSize(oop(addr)->size()), | |
| 8254 "P-mark and computed size do not agree"); | |
| 8255 } | |
|
2132
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1994
diff
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|
8256 #endif |
| 0 | 8257 |
| 8258 } else { | |
| 8259 // This should be an initialized object that's alive. | |
|
6725
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coleenp
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6197
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changeset
|
8260 assert(oop(addr)->klass_or_null() != NULL, |
| 0 | 8261 "Should be an initialized object"); |
| 8262 // Ignore mark word because we are running concurrent with mutators | |
| 8263 assert(oop(addr)->is_oop(true), "live block should be an oop"); | |
| 8264 // Verify that the bit map has no bits marked between | |
| 8265 // addr and purported end of this block. | |
| 8266 size = CompactibleFreeListSpace::adjustObjectSize(oop(addr)->size()); | |
| 8267 assert(size >= 3, "Necessary for Printezis marks to work"); | |
| 8268 assert(!_bitMap->isMarked(addr+1), "Tautology for this control point"); | |
| 8269 DEBUG_ONLY(_bitMap->verifyNoOneBitsInRange(addr+2, addr+size);) | |
| 8270 } | |
| 8271 return size; | |
| 8272 } | |
| 8273 | |
|
2132
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1994
diff
changeset
|
8274 void SweepClosure::do_post_free_or_garbage_chunk(FreeChunk* fc, |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
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|
8275 size_t chunkSize) { |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
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|
8276 // do_post_free_or_garbage_chunk() should only be called in the case |
|
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
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|
8277 // of the adaptive free list allocator. |
|
6028
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jmasa
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6026
diff
changeset
|
8278 const bool fcInFreeLists = fc->is_free(); |
| 0 | 8279 assert(_sp->adaptive_freelists(), "Should only be used in this case."); |
| 8280 assert((HeapWord*)fc <= _limit, "sweep invariant"); | |
| 8281 if (CMSTestInFreeList && fcInFreeLists) { | |
|
6028
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jmasa
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6026
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|
8282 assert(_sp->verify_chunk_in_free_list(fc), "free chunk is not in free lists"); |
|
2132
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1994
diff
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|
8283 } |
| 0 | 8284 |
| 8285 if (CMSTraceSweeper) { | |
| 8286 gclog_or_tty->print_cr(" -- pick up another chunk at 0x%x (%d)", fc, chunkSize); | |
| 8287 } | |
| 8288 | |
|
3746
537a4053b0f9
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3356
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changeset
|
8289 HeapWord* const fc_addr = (HeapWord*) fc; |
| 0 | 8290 |
| 8291 bool coalesce; | |
|
3746
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|
8292 const size_t left = pointer_delta(fc_addr, freeFinger()); |
|
537a4053b0f9
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|
8293 const size_t right = chunkSize; |
| 0 | 8294 switch (FLSCoalescePolicy) { |
| 8295 // numeric value forms a coalition aggressiveness metric | |
| 8296 case 0: { // never coalesce | |
| 8297 coalesce = false; | |
| 8298 break; | |
| 8299 } | |
| 8300 case 1: { // coalesce if left & right chunks on overpopulated lists | |
| 8301 coalesce = _sp->coalOverPopulated(left) && | |
| 8302 _sp->coalOverPopulated(right); | |
| 8303 break; | |
| 8304 } | |
| 8305 case 2: { // coalesce if left chunk on overpopulated list (default) | |
| 8306 coalesce = _sp->coalOverPopulated(left); | |
| 8307 break; | |
| 8308 } | |
| 8309 case 3: { // coalesce if left OR right chunk on overpopulated list | |
| 8310 coalesce = _sp->coalOverPopulated(left) || | |
| 8311 _sp->coalOverPopulated(right); | |
| 8312 break; | |
| 8313 } | |
| 8314 case 4: { // always coalesce | |
| 8315 coalesce = true; | |
| 8316 break; | |
| 8317 } | |
| 8318 default: | |
| 8319 ShouldNotReachHere(); | |
| 8320 } | |
| 8321 | |
| 8322 // Should the current free range be coalesced? | |
| 8323 // If the chunk is in a free range and either we decided to coalesce above | |
| 8324 // or the chunk is near the large block at the end of the heap | |
| 8325 // (isNearLargestChunk() returns true), then coalesce this chunk. | |
|
3746
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3356
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|
8326 const bool doCoalesce = inFreeRange() |
|
537a4053b0f9
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3356
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|
8327 && (coalesce || _g->isNearLargestChunk(fc_addr)); |
| 0 | 8328 if (doCoalesce) { |
| 8329 // Coalesce the current free range on the left with the new | |
| 8330 // chunk on the right. If either is on a free list, | |
| 8331 // it must be removed from the list and stashed in the closure. | |
| 8332 if (freeRangeInFreeLists()) { | |
|
3746
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3356
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|
8333 FreeChunk* const ffc = (FreeChunk*)freeFinger(); |
|
537a4053b0f9
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3356
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|
8334 assert(ffc->size() == pointer_delta(fc_addr, freeFinger()), |
| 0 | 8335 "Size of free range is inconsistent with chunk size."); |
| 8336 if (CMSTestInFreeList) { | |
|
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|
8337 assert(_sp->verify_chunk_in_free_list(ffc), |
| 0 | 8338 "Chunk is not in free lists"); |
| 8339 } | |
| 8340 _sp->coalDeath(ffc->size()); | |
| 8341 _sp->removeFreeChunkFromFreeLists(ffc); | |
| 8342 set_freeRangeInFreeLists(false); | |
| 8343 } | |
| 8344 if (fcInFreeLists) { | |
| 8345 _sp->coalDeath(chunkSize); | |
| 8346 assert(fc->size() == chunkSize, | |
| 8347 "The chunk has the wrong size or is not in the free lists"); | |
| 8348 _sp->removeFreeChunkFromFreeLists(fc); | |
| 8349 } | |
| 8350 set_lastFreeRangeCoalesced(true); | |
|
3746
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3356
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changeset
|
8351 print_free_block_coalesced(fc); |
| 0 | 8352 } else { // not in a free range and/or should not coalesce |
| 8353 // Return the current free range and start a new one. | |
| 8354 if (inFreeRange()) { | |
| 8355 // In a free range but cannot coalesce with the right hand chunk. | |
| 8356 // Put the current free range into the free lists. | |
|
2132
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1994
diff
changeset
|
8357 flush_cur_free_chunk(freeFinger(), |
|
3746
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ysr
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3356
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changeset
|
8358 pointer_delta(fc_addr, freeFinger())); |
| 0 | 8359 } |
| 8360 // Set up for new free range. Pass along whether the right hand | |
| 8361 // chunk is in the free lists. | |
| 8362 initialize_free_range((HeapWord*)fc, fcInFreeLists); | |
| 8363 } | |
| 8364 } | |
|
2132
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ysr
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1994
diff
changeset
|
8365 |
|
3746
537a4053b0f9
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ysr
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3356
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changeset
|
8366 // Lookahead flush: |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8367 // If we are tracking a free range, and this is the last chunk that |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
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changeset
|
8368 // we'll look at because its end crosses past _limit, we'll preemptively |
|
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|
8369 // flush it along with any free range we may be holding on to. Note that |
|
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8370 // this can be the case only for an already free or freshly garbage |
|
537a4053b0f9
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|
8371 // chunk. If this block is an object, it can never straddle |
|
537a4053b0f9
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|
8372 // over _limit. The "straddling" occurs when _limit is set at |
|
537a4053b0f9
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|
8373 // the previous end of the space when this cycle started, and |
|
537a4053b0f9
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|
8374 // a subsequent heap expansion caused the previously co-terminal |
|
537a4053b0f9
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|
8375 // free block to be coalesced with the newly expanded portion, |
|
537a4053b0f9
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|
8376 // thus rendering _limit a non-block-boundary making it dangerous |
|
537a4053b0f9
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|
8377 // for the sweeper to step over and examine. |
|
537a4053b0f9
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|
8378 void SweepClosure::lookahead_and_flush(FreeChunk* fc, size_t chunk_size) { |
|
537a4053b0f9
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|
8379 assert(inFreeRange(), "Should only be called if currently in a free range."); |
|
537a4053b0f9
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|
8380 HeapWord* const eob = ((HeapWord*)fc) + chunk_size; |
|
537a4053b0f9
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|
8381 assert(_sp->used_region().contains(eob - 1), |
|
537a4053b0f9
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|
8382 err_msg("eob = " PTR_FORMAT " out of bounds wrt _sp = [" PTR_FORMAT "," PTR_FORMAT ")" |
|
537a4053b0f9
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|
8383 " when examining fc = " PTR_FORMAT "(" SIZE_FORMAT ")", |
|
537a4053b0f9
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|
8384 _limit, _sp->bottom(), _sp->end(), fc, chunk_size)); |
|
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|
8385 if (eob >= _limit) { |
|
6028
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|
8386 assert(eob == _limit || fc->is_free(), "Only a free chunk should allow us to cross over the limit"); |
|
3746
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|
8387 if (CMSTraceSweeper) { |
|
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|
8388 gclog_or_tty->print_cr("_limit " PTR_FORMAT " reached or crossed by block " |
|
537a4053b0f9
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|
8389 "[" PTR_FORMAT "," PTR_FORMAT ") in space " |
|
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|
8390 "[" PTR_FORMAT "," PTR_FORMAT ")", |
|
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|
8391 _limit, fc, eob, _sp->bottom(), _sp->end()); |
|
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|
8392 } |
|
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|
8393 // Return the storage we are tracking back into the free lists. |
|
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|
8394 if (CMSTraceSweeper) { |
|
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|
8395 gclog_or_tty->print_cr("Flushing ... "); |
|
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|
8396 } |
|
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|
8397 assert(freeFinger() < eob, "Error"); |
|
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|
8398 flush_cur_free_chunk( freeFinger(), pointer_delta(eob, freeFinger())); |
|
537a4053b0f9
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|
8399 } |
|
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|
8400 } |
|
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|
8401 |
|
2132
4947ee68d19c
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|
8402 void SweepClosure::flush_cur_free_chunk(HeapWord* chunk, size_t size) { |
| 0 | 8403 assert(inFreeRange(), "Should only be called if currently in a free range."); |
| 8404 assert(size > 0, | |
| 8405 "A zero sized chunk cannot be added to the free lists."); | |
| 8406 if (!freeRangeInFreeLists()) { | |
|
2132
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diff
changeset
|
8407 if (CMSTestInFreeList) { |
| 0 | 8408 FreeChunk* fc = (FreeChunk*) chunk; |
|
6028
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|
8409 fc->set_size(size); |
|
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|
8410 assert(!_sp->verify_chunk_in_free_list(fc), |
| 0 | 8411 "chunk should not be in free lists yet"); |
| 8412 } | |
| 8413 if (CMSTraceSweeper) { | |
| 8414 gclog_or_tty->print_cr(" -- add free block 0x%x (%d) to free lists", | |
| 8415 chunk, size); | |
| 8416 } | |
| 8417 // A new free range is going to be starting. The current | |
| 8418 // free range has not been added to the free lists yet or | |
| 8419 // was removed so add it back. | |
| 8420 // If the current free range was coalesced, then the death | |
| 8421 // of the free range was recorded. Record a birth now. | |
| 8422 if (lastFreeRangeCoalesced()) { | |
| 8423 _sp->coalBirth(size); | |
| 8424 } | |
| 8425 _sp->addChunkAndRepairOffsetTable(chunk, size, | |
| 8426 lastFreeRangeCoalesced()); | |
|
3746
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|
8427 } else if (CMSTraceSweeper) { |
|
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|
8428 gclog_or_tty->print_cr("Already in free list: nothing to flush"); |
| 0 | 8429 } |
| 8430 set_inFreeRange(false); | |
| 8431 set_freeRangeInFreeLists(false); | |
| 8432 } | |
| 8433 | |
| 8434 // We take a break if we've been at this for a while, | |
| 8435 // so as to avoid monopolizing the locks involved. | |
| 8436 void SweepClosure::do_yield_work(HeapWord* addr) { | |
| 8437 // Return current free chunk being used for coalescing (if any) | |
| 8438 // to the appropriate freelist. After yielding, the next | |
| 8439 // free block encountered will start a coalescing range of | |
| 8440 // free blocks. If the next free block is adjacent to the | |
| 8441 // chunk just flushed, they will need to wait for the next | |
| 8442 // sweep to be coalesced. | |
| 8443 if (inFreeRange()) { | |
|
2132
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1994
diff
changeset
|
8444 flush_cur_free_chunk(freeFinger(), pointer_delta(addr, freeFinger())); |
| 0 | 8445 } |
| 8446 | |
| 8447 // First give up the locks, then yield, then re-lock. | |
| 8448 // We should probably use a constructor/destructor idiom to | |
| 8449 // do this unlock/lock or modify the MutexUnlocker class to | |
| 8450 // serve our purpose. XXX | |
| 8451 assert_lock_strong(_bitMap->lock()); | |
| 8452 assert_lock_strong(_freelistLock); | |
| 8453 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
| 8454 "CMS thread should hold CMS token"); | |
| 8455 _bitMap->lock()->unlock(); | |
| 8456 _freelistLock->unlock(); | |
| 8457 ConcurrentMarkSweepThread::desynchronize(true); | |
| 8458 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 8459 _collector->stopTimer(); | |
| 8460 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
| 8461 if (PrintCMSStatistics != 0) { | |
| 8462 _collector->incrementYields(); | |
| 8463 } | |
| 8464 _collector->icms_wait(); | |
| 8465 | |
| 8466 // See the comment in coordinator_yield() | |
| 8467 for (unsigned i = 0; i < CMSYieldSleepCount && | |
| 8468 ConcurrentMarkSweepThread::should_yield() && | |
| 8469 !CMSCollector::foregroundGCIsActive(); ++i) { | |
| 8470 os::sleep(Thread::current(), 1, false); | |
| 8471 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
| 8472 } | |
| 8473 | |
| 8474 ConcurrentMarkSweepThread::synchronize(true); | |
| 8475 _freelistLock->lock(); | |
| 8476 _bitMap->lock()->lock_without_safepoint_check(); | |
| 8477 _collector->startTimer(); | |
| 8478 } | |
| 8479 | |
| 8480 #ifndef PRODUCT | |
| 8481 // This is actually very useful in a product build if it can | |
| 8482 // be called from the debugger. Compile it into the product | |
| 8483 // as needed. | |
|
6028
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|
8484 bool debug_verify_chunk_in_free_list(FreeChunk* fc) { |
|
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
parents:
6026
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|
8485 return debug_cms_space->verify_chunk_in_free_list(fc); |
| 0 | 8486 } |
|
3746
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|
8487 #endif |
|
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|
8488 |
|
537a4053b0f9
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|
8489 void SweepClosure::print_free_block_coalesced(FreeChunk* fc) const { |
| 0 | 8490 if (CMSTraceSweeper) { |
|
3746
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|
8491 gclog_or_tty->print_cr("Sweep:coal_free_blk " PTR_FORMAT " (" SIZE_FORMAT ")", |
|
537a4053b0f9
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|
8492 fc, fc->size()); |
|
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|
8493 } |
|
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|
8494 } |
| 0 | 8495 |
| 8496 // CMSIsAliveClosure | |
| 8497 bool CMSIsAliveClosure::do_object_b(oop obj) { | |
| 8498 HeapWord* addr = (HeapWord*)obj; | |
| 8499 return addr != NULL && | |
| 8500 (!_span.contains(addr) || _bit_map->isMarked(addr)); | |
| 8501 } | |
| 8502 | |
|
6725
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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6197
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|
8503 |
| 935 | 8504 CMSKeepAliveClosure::CMSKeepAliveClosure( CMSCollector* collector, |
| 8505 MemRegion span, | |
| 8506 CMSBitMap* bit_map, CMSMarkStack* mark_stack, | |
|
6725
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6964458: Reimplement class meta-data storage to use native memory
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|
8507 bool cpc): |
|
da91efe96a93
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|
8508 _collector(collector), |
| 935 | 8509 _span(span), |
| 8510 _bit_map(bit_map), | |
| 8511 _mark_stack(mark_stack), | |
| 8512 _concurrent_precleaning(cpc) { | |
| 8513 assert(!_span.is_empty(), "Empty span could spell trouble"); | |
| 8514 } | |
| 8515 | |
| 8516 | |
| 0 | 8517 // CMSKeepAliveClosure: the serial version |
|
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|
8518 void CMSKeepAliveClosure::do_oop(oop obj) { |
|
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|
8519 HeapWord* addr = (HeapWord*)obj; |
| 0 | 8520 if (_span.contains(addr) && |
| 8521 !_bit_map->isMarked(addr)) { | |
| 8522 _bit_map->mark(addr); | |
| 8523 bool simulate_overflow = false; | |
| 8524 NOT_PRODUCT( | |
| 8525 if (CMSMarkStackOverflowALot && | |
| 8526 _collector->simulate_overflow()) { | |
| 8527 // simulate a stack overflow | |
| 8528 simulate_overflow = true; | |
| 8529 } | |
| 8530 ) | |
|
113
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|
8531 if (simulate_overflow || !_mark_stack->push(obj)) { |
|
452
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6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
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|
8532 if (_concurrent_precleaning) { |
|
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diff
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|
8533 // We dirty the overflown object and let the remark |
|
00b023ae2d78
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360
diff
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|
8534 // phase deal with it. |
|
00b023ae2d78
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|
8535 assert(_collector->overflow_list_is_empty(), "Error"); |
|
00b023ae2d78
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|
8536 // In the case of object arrays, we need to dirty all of |
|
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|
8537 // the cards that the object spans. No locking or atomics |
|
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360
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|
8538 // are needed since no one else can be mutating the mod union |
|
00b023ae2d78
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360
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|
8539 // table. |
|
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
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360
diff
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|
8540 if (obj->is_objArray()) { |
|
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6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
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diff
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|
8541 size_t sz = obj->size(); |
|
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|
8542 HeapWord* end_card_addr = |
|
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ysr
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360
diff
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|
8543 (HeapWord*)round_to((intptr_t)(addr+sz), CardTableModRefBS::card_size); |
|
00b023ae2d78
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|
8544 MemRegion redirty_range = MemRegion(addr, end_card_addr); |
|
00b023ae2d78
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360
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|
8545 assert(!redirty_range.is_empty(), "Arithmetical tautology"); |
|
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ysr
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360
diff
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|
8546 _collector->_modUnionTable.mark_range(redirty_range); |
|
00b023ae2d78
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360
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|
8547 } else { |
|
00b023ae2d78
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diff
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|
8548 _collector->_modUnionTable.mark(addr); |
|
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|
8549 } |
|
00b023ae2d78
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|
8550 _collector->_ser_kac_preclean_ovflw++; |
|
00b023ae2d78
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|
8551 } else { |
|
00b023ae2d78
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|
8552 _collector->push_on_overflow_list(obj); |
|
00b023ae2d78
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|
8553 _collector->_ser_kac_ovflw++; |
|
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|
8554 } |
| 0 | 8555 } |
| 8556 } | |
| 8557 } | |
| 8558 | |
|
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|
8559 void CMSKeepAliveClosure::do_oop(oop* p) { CMSKeepAliveClosure::do_oop_work(p); } |
|
ba764ed4b6f2
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|
8560 void CMSKeepAliveClosure::do_oop(narrowOop* p) { CMSKeepAliveClosure::do_oop_work(p); } |
|
ba764ed4b6f2
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94
diff
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|
8561 |
| 0 | 8562 // CMSParKeepAliveClosure: a parallel version of the above. |
| 8563 // The work queues are private to each closure (thread), | |
| 8564 // but (may be) available for stealing by other threads. | |
|
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8565 void CMSParKeepAliveClosure::do_oop(oop obj) { |
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8566 HeapWord* addr = (HeapWord*)obj; |
| 0 | 8567 if (_span.contains(addr) && |
| 8568 !_bit_map->isMarked(addr)) { | |
| 8569 // In general, during recursive tracing, several threads | |
| 8570 // may be concurrently getting here; the first one to | |
| 8571 // "tag" it, claims it. | |
| 8572 if (_bit_map->par_mark(addr)) { | |
|
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8573 bool res = _work_queue->push(obj); |
| 0 | 8574 assert(res, "Low water mark should be much less than capacity"); |
| 8575 // Do a recursive trim in the hope that this will keep | |
| 8576 // stack usage lower, but leave some oops for potential stealers | |
| 8577 trim_queue(_low_water_mark); | |
| 8578 } // Else, another thread got there first | |
| 8579 } | |
| 8580 } | |
| 8581 | |
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8582 void CMSParKeepAliveClosure::do_oop(oop* p) { CMSParKeepAliveClosure::do_oop_work(p); } |
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8583 void CMSParKeepAliveClosure::do_oop(narrowOop* p) { CMSParKeepAliveClosure::do_oop_work(p); } |
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8584 |
| 0 | 8585 void CMSParKeepAliveClosure::trim_queue(uint max) { |
| 8586 while (_work_queue->size() > max) { | |
| 8587 oop new_oop; | |
| 8588 if (_work_queue->pop_local(new_oop)) { | |
| 8589 assert(new_oop != NULL && new_oop->is_oop(), "Expected an oop"); | |
| 8590 assert(_bit_map->isMarked((HeapWord*)new_oop), | |
| 8591 "no white objects on this stack!"); | |
| 8592 assert(_span.contains((HeapWord*)new_oop), "Out of bounds oop"); | |
| 8593 // iterate over the oops in this oop, marking and pushing | |
| 8594 // the ones in CMS heap (i.e. in _span). | |
| 8595 new_oop->oop_iterate(&_mark_and_push); | |
| 8596 } | |
| 8597 } | |
| 8598 } | |
| 8599 | |
| 935 | 8600 CMSInnerParMarkAndPushClosure::CMSInnerParMarkAndPushClosure( |
| 8601 CMSCollector* collector, | |
| 8602 MemRegion span, CMSBitMap* bit_map, | |
| 8603 OopTaskQueue* work_queue): | |
|
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8604 _collector(collector), |
| 935 | 8605 _span(span), |
| 8606 _bit_map(bit_map), | |
| 8607 _work_queue(work_queue) { } | |
| 8608 | |
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8609 void CMSInnerParMarkAndPushClosure::do_oop(oop obj) { |
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8610 HeapWord* addr = (HeapWord*)obj; |
| 0 | 8611 if (_span.contains(addr) && |
| 8612 !_bit_map->isMarked(addr)) { | |
| 8613 if (_bit_map->par_mark(addr)) { | |
| 8614 bool simulate_overflow = false; | |
| 8615 NOT_PRODUCT( | |
| 8616 if (CMSMarkStackOverflowALot && | |
| 8617 _collector->par_simulate_overflow()) { | |
| 8618 // simulate a stack overflow | |
| 8619 simulate_overflow = true; | |
| 8620 } | |
| 8621 ) | |
|
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8622 if (simulate_overflow || !_work_queue->push(obj)) { |
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8623 _collector->par_push_on_overflow_list(obj); |
| 0 | 8624 _collector->_par_kac_ovflw++; |
| 8625 } | |
| 8626 } // Else another thread got there already | |
| 8627 } | |
| 8628 } | |
| 8629 | |
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8630 void CMSInnerParMarkAndPushClosure::do_oop(oop* p) { CMSInnerParMarkAndPushClosure::do_oop_work(p); } |
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8631 void CMSInnerParMarkAndPushClosure::do_oop(narrowOop* p) { CMSInnerParMarkAndPushClosure::do_oop_work(p); } |
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8632 |
| 0 | 8633 ////////////////////////////////////////////////////////////////// |
| 8634 // CMSExpansionCause ///////////////////////////// | |
| 8635 ////////////////////////////////////////////////////////////////// | |
| 8636 const char* CMSExpansionCause::to_string(CMSExpansionCause::Cause cause) { | |
| 8637 switch (cause) { | |
| 8638 case _no_expansion: | |
| 8639 return "No expansion"; | |
| 8640 case _satisfy_free_ratio: | |
| 8641 return "Free ratio"; | |
| 8642 case _satisfy_promotion: | |
| 8643 return "Satisfy promotion"; | |
| 8644 case _satisfy_allocation: | |
| 8645 return "allocation"; | |
| 8646 case _allocate_par_lab: | |
| 8647 return "Par LAB"; | |
| 8648 case _allocate_par_spooling_space: | |
| 8649 return "Par Spooling Space"; | |
| 8650 case _adaptive_size_policy: | |
| 8651 return "Ergonomics"; | |
| 8652 default: | |
| 8653 return "unknown"; | |
| 8654 } | |
| 8655 } | |
| 8656 | |
| 8657 void CMSDrainMarkingStackClosure::do_void() { | |
| 8658 // the max number to take from overflow list at a time | |
| 8659 const size_t num = _mark_stack->capacity()/4; | |
|
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8660 assert(!_concurrent_precleaning || _collector->overflow_list_is_empty(), |
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8661 "Overflow list should be NULL during concurrent phases"); |
| 0 | 8662 while (!_mark_stack->isEmpty() || |
| 8663 // if stack is empty, check the overflow list | |
| 8664 _collector->take_from_overflow_list(num, _mark_stack)) { | |
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8665 oop obj = _mark_stack->pop(); |
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8666 HeapWord* addr = (HeapWord*)obj; |
| 0 | 8667 assert(_span.contains(addr), "Should be within span"); |
| 8668 assert(_bit_map->isMarked(addr), "Should be marked"); | |
|
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8669 assert(obj->is_oop(), "Should be an oop"); |
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8670 obj->oop_iterate(_keep_alive); |
| 0 | 8671 } |
| 8672 } | |
| 8673 | |
| 8674 void CMSParDrainMarkingStackClosure::do_void() { | |
| 8675 // drain queue | |
| 8676 trim_queue(0); | |
| 8677 } | |
| 8678 | |
| 8679 // Trim our work_queue so its length is below max at return | |
| 8680 void CMSParDrainMarkingStackClosure::trim_queue(uint max) { | |
| 8681 while (_work_queue->size() > max) { | |
| 8682 oop new_oop; | |
| 8683 if (_work_queue->pop_local(new_oop)) { | |
| 8684 assert(new_oop->is_oop(), "Expected an oop"); | |
| 8685 assert(_bit_map->isMarked((HeapWord*)new_oop), | |
| 8686 "no white objects on this stack!"); | |
| 8687 assert(_span.contains((HeapWord*)new_oop), "Out of bounds oop"); | |
| 8688 // iterate over the oops in this oop, marking and pushing | |
| 8689 // the ones in CMS heap (i.e. in _span). | |
| 8690 new_oop->oop_iterate(&_mark_and_push); | |
| 8691 } | |
| 8692 } | |
| 8693 } | |
| 8694 | |
| 8695 //////////////////////////////////////////////////////////////////// | |
| 8696 // Support for Marking Stack Overflow list handling and related code | |
| 8697 //////////////////////////////////////////////////////////////////// | |
| 8698 // Much of the following code is similar in shape and spirit to the | |
| 8699 // code used in ParNewGC. We should try and share that code | |
| 8700 // as much as possible in the future. | |
| 8701 | |
| 8702 #ifndef PRODUCT | |
| 8703 // Debugging support for CMSStackOverflowALot | |
| 8704 | |
| 8705 // It's OK to call this multi-threaded; the worst thing | |
| 8706 // that can happen is that we'll get a bunch of closely | |
| 8707 // spaced simulated oveflows, but that's OK, in fact | |
| 8708 // probably good as it would exercise the overflow code | |
| 8709 // under contention. | |
| 8710 bool CMSCollector::simulate_overflow() { | |
| 8711 if (_overflow_counter-- <= 0) { // just being defensive | |
| 8712 _overflow_counter = CMSMarkStackOverflowInterval; | |
| 8713 return true; | |
| 8714 } else { | |
| 8715 return false; | |
| 8716 } | |
| 8717 } | |
| 8718 | |
| 8719 bool CMSCollector::par_simulate_overflow() { | |
| 8720 return simulate_overflow(); | |
| 8721 } | |
| 8722 #endif | |
| 8723 | |
| 8724 // Single-threaded | |
| 8725 bool CMSCollector::take_from_overflow_list(size_t num, CMSMarkStack* stack) { | |
| 8726 assert(stack->isEmpty(), "Expected precondition"); | |
| 8727 assert(stack->capacity() > num, "Shouldn't bite more than can chew"); | |
| 8728 size_t i = num; | |
| 8729 oop cur = _overflow_list; | |
| 8730 const markOop proto = markOopDesc::prototype(); | |
| 534 | 8731 NOT_PRODUCT(ssize_t n = 0;) |
| 0 | 8732 for (oop next; i > 0 && cur != NULL; cur = next, i--) { |
| 8733 next = oop(cur->mark()); | |
| 8734 cur->set_mark(proto); // until proven otherwise | |
| 8735 assert(cur->is_oop(), "Should be an oop"); | |
| 8736 bool res = stack->push(cur); | |
| 8737 assert(res, "Bit off more than can chew?"); | |
| 8738 NOT_PRODUCT(n++;) | |
| 8739 } | |
| 8740 _overflow_list = cur; | |
| 8741 #ifndef PRODUCT | |
| 8742 assert(_num_par_pushes >= n, "Too many pops?"); | |
| 8743 _num_par_pushes -=n; | |
| 8744 #endif | |
| 8745 return !stack->isEmpty(); | |
| 8746 } | |
| 8747 | |
| 534 | 8748 #define BUSY (oop(0x1aff1aff)) |
| 8749 // (MT-safe) Get a prefix of at most "num" from the list. | |
| 8750 // The overflow list is chained through the mark word of | |
| 8751 // each object in the list. We fetch the entire list, | |
| 8752 // break off a prefix of the right size and return the | |
| 8753 // remainder. If other threads try to take objects from | |
| 8754 // the overflow list at that time, they will wait for | |
| 8755 // some time to see if data becomes available. If (and | |
| 8756 // only if) another thread places one or more object(s) | |
| 8757 // on the global list before we have returned the suffix | |
| 8758 // to the global list, we will walk down our local list | |
| 8759 // to find its end and append the global list to | |
| 8760 // our suffix before returning it. This suffix walk can | |
| 8761 // prove to be expensive (quadratic in the amount of traffic) | |
| 8762 // when there are many objects in the overflow list and | |
| 8763 // there is much producer-consumer contention on the list. | |
| 8764 // *NOTE*: The overflow list manipulation code here and | |
| 8765 // in ParNewGeneration:: are very similar in shape, | |
| 8766 // except that in the ParNew case we use the old (from/eden) | |
| 8767 // copy of the object to thread the list via its klass word. | |
| 8768 // Because of the common code, if you make any changes in | |
| 8769 // the code below, please check the ParNew version to see if | |
| 8770 // similar changes might be needed. | |
| 8771 // CR 6797058 has been filed to consolidate the common code. | |
| 0 | 8772 bool CMSCollector::par_take_from_overflow_list(size_t num, |
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8773 OopTaskQueue* work_q, |
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8774 int no_of_gc_threads) { |
| 534 | 8775 assert(work_q->size() == 0, "First empty local work queue"); |
| 0 | 8776 assert(num < work_q->max_elems(), "Can't bite more than we can chew"); |
| 8777 if (_overflow_list == NULL) { | |
| 8778 return false; | |
| 8779 } | |
| 8780 // Grab the entire list; we'll put back a suffix | |
| 534 | 8781 oop prefix = (oop)Atomic::xchg_ptr(BUSY, &_overflow_list); |
| 8782 Thread* tid = Thread::current(); | |
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8783 // Before "no_of_gc_threads" was introduced CMSOverflowSpinCount was |
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8784 // set to ParallelGCThreads. |
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8785 size_t CMSOverflowSpinCount = (size_t) no_of_gc_threads; // was ParallelGCThreads; |
| 534 | 8786 size_t sleep_time_millis = MAX2((size_t)1, num/100); |
| 8787 // If the list is busy, we spin for a short while, | |
| 8788 // sleeping between attempts to get the list. | |
| 8789 for (size_t spin = 0; prefix == BUSY && spin < CMSOverflowSpinCount; spin++) { | |
| 8790 os::sleep(tid, sleep_time_millis, false); | |
| 8791 if (_overflow_list == NULL) { | |
| 8792 // Nothing left to take | |
| 8793 return false; | |
| 8794 } else if (_overflow_list != BUSY) { | |
| 8795 // Try and grab the prefix | |
| 8796 prefix = (oop)Atomic::xchg_ptr(BUSY, &_overflow_list); | |
| 8797 } | |
| 8798 } | |
| 8799 // If the list was found to be empty, or we spun long | |
| 8800 // enough, we give up and return empty-handed. If we leave | |
| 8801 // the list in the BUSY state below, it must be the case that | |
| 8802 // some other thread holds the overflow list and will set it | |
| 8803 // to a non-BUSY state in the future. | |
| 8804 if (prefix == NULL || prefix == BUSY) { | |
| 8805 // Nothing to take or waited long enough | |
| 8806 if (prefix == NULL) { | |
| 8807 // Write back the NULL in case we overwrote it with BUSY above | |
| 8808 // and it is still the same value. | |
| 8809 (void) Atomic::cmpxchg_ptr(NULL, &_overflow_list, BUSY); | |
| 8810 } | |
| 8811 return false; | |
| 8812 } | |
| 8813 assert(prefix != NULL && prefix != BUSY, "Error"); | |
| 0 | 8814 size_t i = num; |
| 8815 oop cur = prefix; | |
| 534 | 8816 // Walk down the first "num" objects, unless we reach the end. |
| 0 | 8817 for (; i > 1 && cur->mark() != NULL; cur = oop(cur->mark()), i--); |
| 534 | 8818 if (cur->mark() == NULL) { |
| 8819 // We have "num" or fewer elements in the list, so there | |
| 8820 // is nothing to return to the global list. | |
| 8821 // Write back the NULL in lieu of the BUSY we wrote | |
| 8822 // above, if it is still the same value. | |
| 8823 if (_overflow_list == BUSY) { | |
| 8824 (void) Atomic::cmpxchg_ptr(NULL, &_overflow_list, BUSY); | |
| 8825 } | |
| 8826 } else { | |
| 8827 // Chop off the suffix and rerturn it to the global list. | |
| 8828 assert(cur->mark() != BUSY, "Error"); | |
| 0 | 8829 oop suffix_head = cur->mark(); // suffix will be put back on global list |
| 8830 cur->set_mark(NULL); // break off suffix | |
| 534 | 8831 // It's possible that the list is still in the empty(busy) state |
| 8832 // we left it in a short while ago; in that case we may be | |
| 8833 // able to place back the suffix without incurring the cost | |
| 8834 // of a walk down the list. | |
| 0 | 8835 oop observed_overflow_list = _overflow_list; |
| 534 | 8836 oop cur_overflow_list = observed_overflow_list; |
| 8837 bool attached = false; | |
| 8838 while (observed_overflow_list == BUSY || observed_overflow_list == NULL) { | |
| 0 | 8839 observed_overflow_list = |
| 534 | 8840 (oop) Atomic::cmpxchg_ptr(suffix_head, &_overflow_list, cur_overflow_list); |
| 8841 if (cur_overflow_list == observed_overflow_list) { | |
| 8842 attached = true; | |
| 8843 break; | |
| 8844 } else cur_overflow_list = observed_overflow_list; | |
| 8845 } | |
| 8846 if (!attached) { | |
| 8847 // Too bad, someone else sneaked in (at least) an element; we'll need | |
| 8848 // to do a splice. Find tail of suffix so we can prepend suffix to global | |
| 8849 // list. | |
| 8850 for (cur = suffix_head; cur->mark() != NULL; cur = (oop)(cur->mark())); | |
| 8851 oop suffix_tail = cur; | |
| 8852 assert(suffix_tail != NULL && suffix_tail->mark() == NULL, | |
| 8853 "Tautology"); | |
| 8854 observed_overflow_list = _overflow_list; | |
| 8855 do { | |
| 8856 cur_overflow_list = observed_overflow_list; | |
| 8857 if (cur_overflow_list != BUSY) { | |
| 8858 // Do the splice ... | |
| 8859 suffix_tail->set_mark(markOop(cur_overflow_list)); | |
| 8860 } else { // cur_overflow_list == BUSY | |
| 8861 suffix_tail->set_mark(NULL); | |
| 8862 } | |
| 8863 // ... and try to place spliced list back on overflow_list ... | |
| 8864 observed_overflow_list = | |
| 8865 (oop) Atomic::cmpxchg_ptr(suffix_head, &_overflow_list, cur_overflow_list); | |
| 8866 } while (cur_overflow_list != observed_overflow_list); | |
| 8867 // ... until we have succeeded in doing so. | |
| 8868 } | |
| 0 | 8869 } |
| 8870 | |
| 8871 // Push the prefix elements on work_q | |
| 8872 assert(prefix != NULL, "control point invariant"); | |
| 8873 const markOop proto = markOopDesc::prototype(); | |
| 8874 oop next; | |
| 534 | 8875 NOT_PRODUCT(ssize_t n = 0;) |
| 0 | 8876 for (cur = prefix; cur != NULL; cur = next) { |
| 8877 next = oop(cur->mark()); | |
| 8878 cur->set_mark(proto); // until proven otherwise | |
| 8879 assert(cur->is_oop(), "Should be an oop"); | |
| 8880 bool res = work_q->push(cur); | |
| 8881 assert(res, "Bit off more than we can chew?"); | |
| 8882 NOT_PRODUCT(n++;) | |
| 8883 } | |
| 8884 #ifndef PRODUCT | |
| 8885 assert(_num_par_pushes >= n, "Too many pops?"); | |
| 8886 Atomic::add_ptr(-(intptr_t)n, &_num_par_pushes); | |
| 8887 #endif | |
| 8888 return true; | |
| 8889 } | |
| 8890 | |
| 8891 // Single-threaded | |
| 8892 void CMSCollector::push_on_overflow_list(oop p) { | |
| 8893 NOT_PRODUCT(_num_par_pushes++;) | |
| 8894 assert(p->is_oop(), "Not an oop"); | |
| 8895 preserve_mark_if_necessary(p); | |
| 8896 p->set_mark((markOop)_overflow_list); | |
| 8897 _overflow_list = p; | |
| 8898 } | |
| 8899 | |
| 8900 // Multi-threaded; use CAS to prepend to overflow list | |
| 8901 void CMSCollector::par_push_on_overflow_list(oop p) { | |
| 8902 NOT_PRODUCT(Atomic::inc_ptr(&_num_par_pushes);) | |
| 8903 assert(p->is_oop(), "Not an oop"); | |
| 8904 par_preserve_mark_if_necessary(p); | |
| 8905 oop observed_overflow_list = _overflow_list; | |
| 8906 oop cur_overflow_list; | |
| 8907 do { | |
| 8908 cur_overflow_list = observed_overflow_list; | |
| 534 | 8909 if (cur_overflow_list != BUSY) { |
| 8910 p->set_mark(markOop(cur_overflow_list)); | |
| 8911 } else { | |
| 8912 p->set_mark(NULL); | |
| 8913 } | |
| 0 | 8914 observed_overflow_list = |
| 8915 (oop) Atomic::cmpxchg_ptr(p, &_overflow_list, cur_overflow_list); | |
| 8916 } while (cur_overflow_list != observed_overflow_list); | |
| 8917 } | |
| 534 | 8918 #undef BUSY |
| 0 | 8919 |
| 8920 // Single threaded | |
| 8921 // General Note on GrowableArray: pushes may silently fail | |
| 8922 // because we are (temporarily) out of C-heap for expanding | |
| 8923 // the stack. The problem is quite ubiquitous and affects | |
| 8924 // a lot of code in the JVM. The prudent thing for GrowableArray | |
| 8925 // to do (for now) is to exit with an error. However, that may | |
| 8926 // be too draconian in some cases because the caller may be | |
| 534 | 8927 // able to recover without much harm. For such cases, we |
| 0 | 8928 // should probably introduce a "soft_push" method which returns |
| 8929 // an indication of success or failure with the assumption that | |
| 8930 // the caller may be able to recover from a failure; code in | |
| 8931 // the VM can then be changed, incrementally, to deal with such | |
| 8932 // failures where possible, thus, incrementally hardening the VM | |
| 8933 // in such low resource situations. | |
| 8934 void CMSCollector::preserve_mark_work(oop p, markOop m) { | |
|
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8935 _preserved_oop_stack.push(p); |
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8936 _preserved_mark_stack.push(m); |
| 0 | 8937 assert(m == p->mark(), "Mark word changed"); |
|
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8938 assert(_preserved_oop_stack.size() == _preserved_mark_stack.size(), |
| 0 | 8939 "bijection"); |
| 8940 } | |
| 8941 | |
| 8942 // Single threaded | |
| 8943 void CMSCollector::preserve_mark_if_necessary(oop p) { | |
| 8944 markOop m = p->mark(); | |
| 8945 if (m->must_be_preserved(p)) { | |
| 8946 preserve_mark_work(p, m); | |
| 8947 } | |
| 8948 } | |
| 8949 | |
| 8950 void CMSCollector::par_preserve_mark_if_necessary(oop p) { | |
| 8951 markOop m = p->mark(); | |
| 8952 if (m->must_be_preserved(p)) { | |
| 8953 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); | |
| 8954 // Even though we read the mark word without holding | |
| 8955 // the lock, we are assured that it will not change | |
| 8956 // because we "own" this oop, so no other thread can | |
| 8957 // be trying to push it on the overflow list; see | |
| 8958 // the assertion in preserve_mark_work() that checks | |
| 8959 // that m == p->mark(). | |
| 8960 preserve_mark_work(p, m); | |
| 8961 } | |
| 8962 } | |
| 8963 | |
| 8964 // We should be able to do this multi-threaded, | |
| 8965 // a chunk of stack being a task (this is | |
| 8966 // correct because each oop only ever appears | |
| 8967 // once in the overflow list. However, it's | |
| 8968 // not very easy to completely overlap this with | |
| 8969 // other operations, so will generally not be done | |
| 8970 // until all work's been completed. Because we | |
| 8971 // expect the preserved oop stack (set) to be small, | |
| 8972 // it's probably fine to do this single-threaded. | |
| 8973 // We can explore cleverer concurrent/overlapped/parallel | |
| 8974 // processing of preserved marks if we feel the | |
| 8975 // need for this in the future. Stack overflow should | |
| 8976 // be so rare in practice and, when it happens, its | |
| 8977 // effect on performance so great that this will | |
| 8978 // likely just be in the noise anyway. | |
| 8979 void CMSCollector::restore_preserved_marks_if_any() { | |
| 8980 assert(SafepointSynchronize::is_at_safepoint(), | |
| 8981 "world should be stopped"); | |
| 8982 assert(Thread::current()->is_ConcurrentGC_thread() || | |
| 8983 Thread::current()->is_VM_thread(), | |
| 8984 "should be single-threaded"); | |
|
1836
894b1d7c7e01
6423256: GC stacks should use a better data structure
jcoomes
parents:
1833
diff
changeset
|
8985 assert(_preserved_oop_stack.size() == _preserved_mark_stack.size(), |
|
894b1d7c7e01
6423256: GC stacks should use a better data structure
jcoomes
parents:
1833
diff
changeset
|
8986 "bijection"); |
|
894b1d7c7e01
6423256: GC stacks should use a better data structure
jcoomes
parents:
1833
diff
changeset
|
8987 |
|
894b1d7c7e01
6423256: GC stacks should use a better data structure
jcoomes
parents:
1833
diff
changeset
|
8988 while (!_preserved_oop_stack.is_empty()) { |
|
894b1d7c7e01
6423256: GC stacks should use a better data structure
jcoomes
parents:
1833
diff
changeset
|
8989 oop p = _preserved_oop_stack.pop(); |
| 0 | 8990 assert(p->is_oop(), "Should be an oop"); |
| 8991 assert(_span.contains(p), "oop should be in _span"); | |
| 8992 assert(p->mark() == markOopDesc::prototype(), | |
| 8993 "Set when taken from overflow list"); | |
|
1836
894b1d7c7e01
6423256: GC stacks should use a better data structure
jcoomes
parents:
1833
diff
changeset
|
8994 markOop m = _preserved_mark_stack.pop(); |
| 0 | 8995 p->set_mark(m); |
| 8996 } | |
|
1836
894b1d7c7e01
6423256: GC stacks should use a better data structure
jcoomes
parents:
1833
diff
changeset
|
8997 assert(_preserved_mark_stack.is_empty() && _preserved_oop_stack.is_empty(), |
| 0 | 8998 "stacks were cleared above"); |
| 8999 } | |
| 9000 | |
| 9001 #ifndef PRODUCT | |
| 9002 bool CMSCollector::no_preserved_marks() const { | |
|
1836
894b1d7c7e01
6423256: GC stacks should use a better data structure
jcoomes
parents:
1833
diff
changeset
|
9003 return _preserved_mark_stack.is_empty() && _preserved_oop_stack.is_empty(); |
| 0 | 9004 } |
| 9005 #endif | |
| 9006 | |
| 9007 CMSAdaptiveSizePolicy* ASConcurrentMarkSweepGeneration::cms_size_policy() const | |
| 9008 { | |
| 9009 GenCollectedHeap* gch = (GenCollectedHeap*) GenCollectedHeap::heap(); | |
| 9010 CMSAdaptiveSizePolicy* size_policy = | |
| 9011 (CMSAdaptiveSizePolicy*) gch->gen_policy()->size_policy(); | |
| 9012 assert(size_policy->is_gc_cms_adaptive_size_policy(), | |
| 9013 "Wrong type for size policy"); | |
| 9014 return size_policy; | |
| 9015 } | |
| 9016 | |
| 9017 void ASConcurrentMarkSweepGeneration::resize(size_t cur_promo_size, | |
| 9018 size_t desired_promo_size) { | |
| 9019 if (cur_promo_size < desired_promo_size) { | |
| 9020 size_t expand_bytes = desired_promo_size - cur_promo_size; | |
| 9021 if (PrintAdaptiveSizePolicy && Verbose) { | |
| 9022 gclog_or_tty->print_cr(" ASConcurrentMarkSweepGeneration::resize " | |
| 9023 "Expanding tenured generation by " SIZE_FORMAT " (bytes)", | |
| 9024 expand_bytes); | |
| 9025 } | |
| 9026 expand(expand_bytes, | |
| 9027 MinHeapDeltaBytes, | |
| 9028 CMSExpansionCause::_adaptive_size_policy); | |
| 9029 } else if (desired_promo_size < cur_promo_size) { | |
| 9030 size_t shrink_bytes = cur_promo_size - desired_promo_size; | |
| 9031 if (PrintAdaptiveSizePolicy && Verbose) { | |
| 9032 gclog_or_tty->print_cr(" ASConcurrentMarkSweepGeneration::resize " | |
| 9033 "Shrinking tenured generation by " SIZE_FORMAT " (bytes)", | |
| 9034 shrink_bytes); | |
| 9035 } | |
| 9036 shrink(shrink_bytes); | |
| 9037 } | |
| 9038 } | |
| 9039 | |
| 9040 CMSGCAdaptivePolicyCounters* ASConcurrentMarkSweepGeneration::gc_adaptive_policy_counters() { | |
| 9041 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 9042 CMSGCAdaptivePolicyCounters* counters = | |
| 9043 (CMSGCAdaptivePolicyCounters*) gch->collector_policy()->counters(); | |
| 9044 assert(counters->kind() == GCPolicyCounters::CMSGCAdaptivePolicyCountersKind, | |
| 9045 "Wrong kind of counters"); | |
| 9046 return counters; | |
| 9047 } | |
| 9048 | |
| 9049 | |
| 9050 void ASConcurrentMarkSweepGeneration::update_counters() { | |
| 9051 if (UsePerfData) { | |
| 9052 _space_counters->update_all(); | |
| 9053 _gen_counters->update_all(); | |
| 9054 CMSGCAdaptivePolicyCounters* counters = gc_adaptive_policy_counters(); | |
| 9055 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 9056 CMSGCStats* gc_stats_l = (CMSGCStats*) gc_stats(); | |
| 9057 assert(gc_stats_l->kind() == GCStats::CMSGCStatsKind, | |
| 9058 "Wrong gc statistics type"); | |
| 9059 counters->update_counters(gc_stats_l); | |
| 9060 } | |
| 9061 } | |
| 9062 | |
| 9063 void ASConcurrentMarkSweepGeneration::update_counters(size_t used) { | |
| 9064 if (UsePerfData) { | |
| 9065 _space_counters->update_used(used); | |
| 9066 _space_counters->update_capacity(); | |
| 9067 _gen_counters->update_all(); | |
| 9068 | |
| 9069 CMSGCAdaptivePolicyCounters* counters = gc_adaptive_policy_counters(); | |
| 9070 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 9071 CMSGCStats* gc_stats_l = (CMSGCStats*) gc_stats(); | |
| 9072 assert(gc_stats_l->kind() == GCStats::CMSGCStatsKind, | |
| 9073 "Wrong gc statistics type"); | |
| 9074 counters->update_counters(gc_stats_l); | |
| 9075 } | |
| 9076 } | |
| 9077 | |
| 9078 // The desired expansion delta is computed so that: | |
| 9079 // . desired free percentage or greater is used | |
| 9080 void ASConcurrentMarkSweepGeneration::compute_new_size() { | |
| 9081 assert_locked_or_safepoint(Heap_lock); | |
| 9082 | |
| 9083 GenCollectedHeap* gch = (GenCollectedHeap*) GenCollectedHeap::heap(); | |
| 9084 | |
| 9085 // If incremental collection failed, we just want to expand | |
| 9086 // to the limit. | |
| 9087 if (incremental_collection_failed()) { | |
| 9088 clear_incremental_collection_failed(); | |
| 9089 grow_to_reserved(); | |
| 9090 return; | |
| 9091 } | |
| 9092 | |
| 9093 assert(UseAdaptiveSizePolicy, "Should be using adaptive sizing"); | |
| 9094 | |
| 9095 assert(gch->kind() == CollectedHeap::GenCollectedHeap, | |
| 9096 "Wrong type of heap"); | |
| 9097 int prev_level = level() - 1; | |
| 9098 assert(prev_level >= 0, "The cms generation is the lowest generation"); | |
| 9099 Generation* prev_gen = gch->get_gen(prev_level); | |
| 9100 assert(prev_gen->kind() == Generation::ASParNew, | |
| 9101 "Wrong type of young generation"); | |
| 9102 ParNewGeneration* younger_gen = (ParNewGeneration*) prev_gen; | |
| 9103 size_t cur_eden = younger_gen->eden()->capacity(); | |
| 9104 CMSAdaptiveSizePolicy* size_policy = cms_size_policy(); | |
| 9105 size_t cur_promo = free(); | |
| 9106 size_policy->compute_tenured_generation_free_space(cur_promo, | |
| 9107 max_available(), | |
| 9108 cur_eden); | |
| 9109 resize(cur_promo, size_policy->promo_size()); | |
| 9110 | |
| 9111 // Record the new size of the space in the cms generation | |
| 9112 // that is available for promotions. This is temporary. | |
| 9113 // It should be the desired promo size. | |
| 9114 size_policy->avg_cms_promo()->sample(free()); | |
| 9115 size_policy->avg_old_live()->sample(used()); | |
| 9116 | |
| 9117 if (UsePerfData) { | |
| 9118 CMSGCAdaptivePolicyCounters* counters = gc_adaptive_policy_counters(); | |
| 9119 counters->update_cms_capacity_counter(capacity()); | |
| 9120 } | |
| 9121 } | |
| 9122 | |
| 9123 void ASConcurrentMarkSweepGeneration::shrink_by(size_t desired_bytes) { | |
| 9124 assert_locked_or_safepoint(Heap_lock); | |
| 9125 assert_lock_strong(freelistLock()); | |
| 9126 HeapWord* old_end = _cmsSpace->end(); | |
| 9127 HeapWord* unallocated_start = _cmsSpace->unallocated_block(); | |
| 9128 assert(old_end >= unallocated_start, "Miscalculation of unallocated_start"); | |
| 9129 FreeChunk* chunk_at_end = find_chunk_at_end(); | |
| 9130 if (chunk_at_end == NULL) { | |
| 9131 // No room to shrink | |
| 9132 if (PrintGCDetails && Verbose) { | |
| 9133 gclog_or_tty->print_cr("No room to shrink: old_end " | |
| 9134 PTR_FORMAT " unallocated_start " PTR_FORMAT | |
| 9135 " chunk_at_end " PTR_FORMAT, | |
| 9136 old_end, unallocated_start, chunk_at_end); | |
| 9137 } | |
| 9138 return; | |
| 9139 } else { | |
| 9140 | |
| 9141 // Find the chunk at the end of the space and determine | |
| 9142 // how much it can be shrunk. | |
| 9143 size_t shrinkable_size_in_bytes = chunk_at_end->size(); | |
| 9144 size_t aligned_shrinkable_size_in_bytes = | |
| 9145 align_size_down(shrinkable_size_in_bytes, os::vm_page_size()); | |
| 6885 | 9146 assert(unallocated_start <= (HeapWord*) chunk_at_end->end(), |
| 0 | 9147 "Inconsistent chunk at end of space"); |
| 9148 size_t bytes = MIN2(desired_bytes, aligned_shrinkable_size_in_bytes); | |
| 9149 size_t word_size_before = heap_word_size(_virtual_space.committed_size()); | |
| 9150 | |
| 9151 // Shrink the underlying space | |
| 9152 _virtual_space.shrink_by(bytes); | |
| 9153 if (PrintGCDetails && Verbose) { | |
| 9154 gclog_or_tty->print_cr("ConcurrentMarkSweepGeneration::shrink_by:" | |
| 9155 " desired_bytes " SIZE_FORMAT | |
| 9156 " shrinkable_size_in_bytes " SIZE_FORMAT | |
| 9157 " aligned_shrinkable_size_in_bytes " SIZE_FORMAT | |
| 9158 " bytes " SIZE_FORMAT, | |
| 9159 desired_bytes, shrinkable_size_in_bytes, | |
| 9160 aligned_shrinkable_size_in_bytes, bytes); | |
| 9161 gclog_or_tty->print_cr(" old_end " SIZE_FORMAT | |
| 9162 " unallocated_start " SIZE_FORMAT, | |
| 9163 old_end, unallocated_start); | |
| 9164 } | |
| 9165 | |
| 9166 // If the space did shrink (shrinking is not guaranteed), | |
| 9167 // shrink the chunk at the end by the appropriate amount. | |
| 9168 if (((HeapWord*)_virtual_space.high()) < old_end) { | |
| 9169 size_t new_word_size = | |
| 9170 heap_word_size(_virtual_space.committed_size()); | |
| 9171 | |
| 9172 // Have to remove the chunk from the dictionary because it is changing | |
| 9173 // size and might be someplace elsewhere in the dictionary. | |
| 9174 | |
| 9175 // Get the chunk at end, shrink it, and put it | |
| 9176 // back. | |
| 9177 _cmsSpace->removeChunkFromDictionary(chunk_at_end); | |
| 9178 size_t word_size_change = word_size_before - new_word_size; | |
| 9179 size_t chunk_at_end_old_size = chunk_at_end->size(); | |
| 9180 assert(chunk_at_end_old_size >= word_size_change, | |
| 9181 "Shrink is too large"); | |
|
6028
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
parents:
6026
diff
changeset
|
9182 chunk_at_end->set_size(chunk_at_end_old_size - |
| 0 | 9183 word_size_change); |
| 9184 _cmsSpace->freed((HeapWord*) chunk_at_end->end(), | |
| 9185 word_size_change); | |
| 9186 | |
| 9187 _cmsSpace->returnChunkToDictionary(chunk_at_end); | |
| 9188 | |
| 9189 MemRegion mr(_cmsSpace->bottom(), new_word_size); | |
| 9190 _bts->resize(new_word_size); // resize the block offset shared array | |
| 9191 Universe::heap()->barrier_set()->resize_covered_region(mr); | |
| 9192 _cmsSpace->assert_locked(); | |
| 9193 _cmsSpace->set_end((HeapWord*)_virtual_space.high()); | |
| 9194 | |
| 9195 NOT_PRODUCT(_cmsSpace->dictionary()->verify()); | |
| 9196 | |
| 9197 // update the space and generation capacity counters | |
| 9198 if (UsePerfData) { | |
| 9199 _space_counters->update_capacity(); | |
| 9200 _gen_counters->update_all(); | |
| 9201 } | |
| 9202 | |
| 9203 if (Verbose && PrintGCDetails) { | |
| 9204 size_t new_mem_size = _virtual_space.committed_size(); | |
| 9205 size_t old_mem_size = new_mem_size + bytes; | |
| 9206 gclog_or_tty->print_cr("Shrinking %s from %ldK by %ldK to %ldK", | |
| 9207 name(), old_mem_size/K, bytes/K, new_mem_size/K); | |
| 9208 } | |
| 9209 } | |
| 9210 | |
| 9211 assert(_cmsSpace->unallocated_block() <= _cmsSpace->end(), | |
| 9212 "Inconsistency at end of space"); | |
| 6885 | 9213 assert(chunk_at_end->end() == (uintptr_t*) _cmsSpace->end(), |
| 0 | 9214 "Shrinking is inconsistent"); |
| 9215 return; | |
| 9216 } | |
| 9217 } | |
| 9218 | |
| 9219 // Transfer some number of overflown objects to usual marking | |
| 9220 // stack. Return true if some objects were transferred. | |
| 9221 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
|
9222 size_t num = MIN2((size_t)(_mark_stack->capacity() - _mark_stack->length())/4, |
| 0 | 9223 (size_t)ParGCDesiredObjsFromOverflowList); |
| 9224 | |
| 9225 bool res = _collector->take_from_overflow_list(num, _mark_stack); | |
| 9226 assert(_collector->overflow_list_is_empty() || res, | |
| 9227 "If list is not empty, we should have taken something"); | |
| 9228 assert(!res || !_mark_stack->isEmpty(), | |
| 9229 "If we took something, it should now be on our stack"); | |
| 9230 return res; | |
| 9231 } | |
| 9232 | |
| 9233 size_t MarkDeadObjectsClosure::do_blk(HeapWord* addr) { | |
| 9234 size_t res = _sp->block_size_no_stall(addr, _collector); | |
| 9235 if (_sp->block_is_obj(addr)) { | |
| 9236 if (_live_bit_map->isMarked(addr)) { | |
| 9237 // It can't have been dead in a previous cycle | |
| 9238 guarantee(!_dead_bit_map->isMarked(addr), "No resurrection!"); | |
| 9239 } else { | |
| 9240 _dead_bit_map->mark(addr); // mark the dead object | |
| 9241 } | |
| 9242 } | |
|
2226
c5a923563727
6912621: iCMS: Error: assert(_markBitMap.isMarked(addr + 1),"Missing Printezis bit?")
ysr
parents:
2177
diff
changeset
|
9243 // Could be 0, if the block size could not be computed without stalling. |
| 0 | 9244 return res; |
| 9245 } | |
|
1703
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9246 |
|
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
parents:
3293
diff
changeset
|
9247 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
|
9248 |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9249 switch (phase) { |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9250 case CMSCollector::InitialMarking: |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9251 initialize(true /* fullGC */ , |
|
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
parents:
3293
diff
changeset
|
9252 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
|
9253 true /* recordGCBeginTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9254 true /* recordPreGCUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9255 false /* recordPeakUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9256 false /* recordPostGCusage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9257 true /* recordAccumulatedGCTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9258 false /* recordGCEndTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9259 false /* countCollection */ ); |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9260 break; |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9261 |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9262 case CMSCollector::FinalMarking: |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9263 initialize(true /* fullGC */ , |
|
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
parents:
3293
diff
changeset
|
9264 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
|
9265 false /* recordGCBeginTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9266 false /* recordPreGCUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9267 false /* recordPeakUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9268 false /* recordPostGCusage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9269 true /* recordAccumulatedGCTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9270 false /* recordGCEndTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9271 false /* countCollection */ ); |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9272 break; |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9273 |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9274 case CMSCollector::Sweeping: |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9275 initialize(true /* fullGC */ , |
|
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
parents:
3293
diff
changeset
|
9276 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
|
9277 false /* recordGCBeginTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9278 false /* recordPreGCUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9279 true /* recordPeakUsage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9280 true /* recordPostGCusage */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9281 false /* recordAccumulatedGCTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9282 true /* recordGCEndTime */, |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9283 true /* countCollection */ ); |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9284 break; |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9285 |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9286 default: |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9287 ShouldNotReachHere(); |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9288 } |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9289 } |
|
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9290 |