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annotate src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp @ 10972:a0a47b2649a2
Merge
author | ctornqvi |
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date | Fri, 14 Jun 2013 13:11:58 +0200 |
parents | f2110083203d |
children | 71180a6e5080 |
rev | line source |
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0 | 1 /* |
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2 * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved. |
0 | 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
4 * | |
5 * This code is free software; you can redistribute it and/or modify it | |
6 * under the terms of the GNU General Public License version 2 only, as | |
7 * published by the Free Software Foundation. | |
8 * | |
9 * This code is distributed in the hope that it will be useful, but WITHOUT | |
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
12 * version 2 for more details (a copy is included in the LICENSE file that | |
13 * accompanied this code). | |
14 * | |
15 * You should have received a copy of the GNU General Public License version | |
16 * 2 along with this work; if not, write to the Free Software Foundation, | |
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
18 * | |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
0 | 22 * |
23 */ | |
24 | |
1972 | 25 #include "precompiled.hpp" |
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26 #include "classfile/classLoaderData.hpp" |
1972 | 27 #include "classfile/symbolTable.hpp" |
28 #include "classfile/systemDictionary.hpp" | |
29 #include "code/codeCache.hpp" | |
30 #include "gc_implementation/concurrentMarkSweep/cmsAdaptiveSizePolicy.hpp" | |
31 #include "gc_implementation/concurrentMarkSweep/cmsCollectorPolicy.hpp" | |
32 #include "gc_implementation/concurrentMarkSweep/cmsGCAdaptivePolicyCounters.hpp" | |
33 #include "gc_implementation/concurrentMarkSweep/cmsOopClosures.inline.hpp" | |
34 #include "gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.hpp" | |
35 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.inline.hpp" | |
36 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp" | |
37 #include "gc_implementation/concurrentMarkSweep/vmCMSOperations.hpp" | |
38 #include "gc_implementation/parNew/parNewGeneration.hpp" | |
39 #include "gc_implementation/shared/collectorCounters.hpp" | |
10405 | 40 #include "gc_implementation/shared/gcTimer.hpp" |
41 #include "gc_implementation/shared/gcTrace.hpp" | |
42 #include "gc_implementation/shared/gcTraceTime.hpp" | |
1972 | 43 #include "gc_implementation/shared/isGCActiveMark.hpp" |
44 #include "gc_interface/collectedHeap.inline.hpp" | |
10405 | 45 #include "memory/allocation.hpp" |
1972 | 46 #include "memory/cardTableRS.hpp" |
47 #include "memory/collectorPolicy.hpp" | |
48 #include "memory/gcLocker.inline.hpp" | |
49 #include "memory/genCollectedHeap.hpp" | |
50 #include "memory/genMarkSweep.hpp" | |
51 #include "memory/genOopClosures.inline.hpp" | |
52 #include "memory/iterator.hpp" | |
53 #include "memory/referencePolicy.hpp" | |
54 #include "memory/resourceArea.hpp" | |
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55 #include "memory/tenuredGeneration.hpp" |
1972 | 56 #include "oops/oop.inline.hpp" |
57 #include "prims/jvmtiExport.hpp" | |
58 #include "runtime/globals_extension.hpp" | |
59 #include "runtime/handles.inline.hpp" | |
60 #include "runtime/java.hpp" | |
61 #include "runtime/vmThread.hpp" | |
62 #include "services/memoryService.hpp" | |
63 #include "services/runtimeService.hpp" | |
0 | 64 |
65 // statics | |
66 CMSCollector* ConcurrentMarkSweepGeneration::_collector = NULL; | |
10405 | 67 bool CMSCollector::_full_gc_requested = false; |
68 GCCause::Cause CMSCollector::_full_gc_cause = GCCause::_no_gc; | |
0 | 69 |
70 ////////////////////////////////////////////////////////////////// | |
71 // In support of CMS/VM thread synchronization | |
72 ////////////////////////////////////////////////////////////////// | |
73 // We split use of the CGC_lock into 2 "levels". | |
74 // The low-level locking is of the usual CGC_lock monitor. We introduce | |
75 // a higher level "token" (hereafter "CMS token") built on top of the | |
76 // low level monitor (hereafter "CGC lock"). | |
77 // The token-passing protocol gives priority to the VM thread. The | |
78 // CMS-lock doesn't provide any fairness guarantees, but clients | |
79 // should ensure that it is only held for very short, bounded | |
80 // durations. | |
81 // | |
82 // When either of the CMS thread or the VM thread is involved in | |
83 // collection operations during which it does not want the other | |
84 // thread to interfere, it obtains the CMS token. | |
85 // | |
86 // If either thread tries to get the token while the other has | |
87 // it, that thread waits. However, if the VM thread and CMS thread | |
88 // both want the token, then the VM thread gets priority while the | |
89 // CMS thread waits. This ensures, for instance, that the "concurrent" | |
90 // phases of the CMS thread's work do not block out the VM thread | |
91 // for long periods of time as the CMS thread continues to hog | |
92 // the token. (See bug 4616232). | |
93 // | |
94 // The baton-passing functions are, however, controlled by the | |
95 // flags _foregroundGCShouldWait and _foregroundGCIsActive, | |
96 // and here the low-level CMS lock, not the high level token, | |
97 // ensures mutual exclusion. | |
98 // | |
99 // Two important conditions that we have to satisfy: | |
100 // 1. if a thread does a low-level wait on the CMS lock, then it | |
101 // relinquishes the CMS token if it were holding that token | |
102 // when it acquired the low-level CMS lock. | |
103 // 2. any low-level notifications on the low-level lock | |
104 // should only be sent when a thread has relinquished the token. | |
105 // | |
106 // In the absence of either property, we'd have potential deadlock. | |
107 // | |
108 // We protect each of the CMS (concurrent and sequential) phases | |
109 // with the CMS _token_, not the CMS _lock_. | |
110 // | |
111 // The only code protected by CMS lock is the token acquisition code | |
112 // itself, see ConcurrentMarkSweepThread::[de]synchronize(), and the | |
113 // baton-passing code. | |
114 // | |
115 // Unfortunately, i couldn't come up with a good abstraction to factor and | |
116 // hide the naked CGC_lock manipulation in the baton-passing code | |
117 // further below. That's something we should try to do. Also, the proof | |
118 // of correctness of this 2-level locking scheme is far from obvious, | |
119 // and potentially quite slippery. We have an uneasy supsicion, for instance, | |
120 // that there may be a theoretical possibility of delay/starvation in the | |
121 // low-level lock/wait/notify scheme used for the baton-passing because of | |
122 // potential intereference with the priority scheme embodied in the | |
123 // CMS-token-passing protocol. See related comments at a CGC_lock->wait() | |
124 // invocation further below and marked with "XXX 20011219YSR". | |
125 // Indeed, as we note elsewhere, this may become yet more slippery | |
126 // in the presence of multiple CMS and/or multiple VM threads. XXX | |
127 | |
128 class CMSTokenSync: public StackObj { | |
129 private: | |
130 bool _is_cms_thread; | |
131 public: | |
132 CMSTokenSync(bool is_cms_thread): | |
133 _is_cms_thread(is_cms_thread) { | |
134 assert(is_cms_thread == Thread::current()->is_ConcurrentGC_thread(), | |
135 "Incorrect argument to constructor"); | |
136 ConcurrentMarkSweepThread::synchronize(_is_cms_thread); | |
137 } | |
138 | |
139 ~CMSTokenSync() { | |
140 assert(_is_cms_thread ? | |
141 ConcurrentMarkSweepThread::cms_thread_has_cms_token() : | |
142 ConcurrentMarkSweepThread::vm_thread_has_cms_token(), | |
143 "Incorrect state"); | |
144 ConcurrentMarkSweepThread::desynchronize(_is_cms_thread); | |
145 } | |
146 }; | |
147 | |
148 // Convenience class that does a CMSTokenSync, and then acquires | |
149 // upto three locks. | |
150 class CMSTokenSyncWithLocks: public CMSTokenSync { | |
151 private: | |
152 // Note: locks are acquired in textual declaration order | |
153 // and released in the opposite order | |
154 MutexLockerEx _locker1, _locker2, _locker3; | |
155 public: | |
156 CMSTokenSyncWithLocks(bool is_cms_thread, Mutex* mutex1, | |
157 Mutex* mutex2 = NULL, Mutex* mutex3 = NULL): | |
158 CMSTokenSync(is_cms_thread), | |
159 _locker1(mutex1, Mutex::_no_safepoint_check_flag), | |
160 _locker2(mutex2, Mutex::_no_safepoint_check_flag), | |
161 _locker3(mutex3, Mutex::_no_safepoint_check_flag) | |
162 { } | |
163 }; | |
164 | |
165 | |
166 // Wrapper class to temporarily disable icms during a foreground cms collection. | |
167 class ICMSDisabler: public StackObj { | |
168 public: | |
169 // The ctor disables icms and wakes up the thread so it notices the change; | |
170 // the dtor re-enables icms. Note that the CMSCollector methods will check | |
171 // CMSIncrementalMode. | |
172 ICMSDisabler() { CMSCollector::disable_icms(); CMSCollector::start_icms(); } | |
173 ~ICMSDisabler() { CMSCollector::enable_icms(); } | |
174 }; | |
175 | |
176 ////////////////////////////////////////////////////////////////// | |
177 // Concurrent Mark-Sweep Generation ///////////////////////////// | |
178 ////////////////////////////////////////////////////////////////// | |
179 | |
180 NOT_PRODUCT(CompactibleFreeListSpace* debug_cms_space;) | |
181 | |
182 // This struct contains per-thread things necessary to support parallel | |
183 // young-gen collection. | |
6197 | 184 class CMSParGCThreadState: public CHeapObj<mtGC> { |
0 | 185 public: |
186 CFLS_LAB lab; | |
187 PromotionInfo promo; | |
188 | |
189 // Constructor. | |
190 CMSParGCThreadState(CompactibleFreeListSpace* cfls) : lab(cfls) { | |
191 promo.setSpace(cfls); | |
192 } | |
193 }; | |
194 | |
195 ConcurrentMarkSweepGeneration::ConcurrentMarkSweepGeneration( | |
196 ReservedSpace rs, size_t initial_byte_size, int level, | |
197 CardTableRS* ct, bool use_adaptive_freelists, | |
6026 | 198 FreeBlockDictionary<FreeChunk>::DictionaryChoice dictionaryChoice) : |
0 | 199 CardGeneration(rs, initial_byte_size, level, ct), |
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200 _dilatation_factor(((double)MinChunkSize)/((double)(CollectedHeap::min_fill_size()))), |
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201 _debug_collection_type(Concurrent_collection_type), |
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202 _did_compact(false) |
0 | 203 { |
204 HeapWord* bottom = (HeapWord*) _virtual_space.low(); | |
205 HeapWord* end = (HeapWord*) _virtual_space.high(); | |
206 | |
207 _direct_allocated_words = 0; | |
208 NOT_PRODUCT( | |
209 _numObjectsPromoted = 0; | |
210 _numWordsPromoted = 0; | |
211 _numObjectsAllocated = 0; | |
212 _numWordsAllocated = 0; | |
213 ) | |
214 | |
215 _cmsSpace = new CompactibleFreeListSpace(_bts, MemRegion(bottom, end), | |
216 use_adaptive_freelists, | |
217 dictionaryChoice); | |
218 NOT_PRODUCT(debug_cms_space = _cmsSpace;) | |
219 if (_cmsSpace == NULL) { | |
220 vm_exit_during_initialization( | |
221 "CompactibleFreeListSpace allocation failure"); | |
222 } | |
223 _cmsSpace->_gen = this; | |
224 | |
225 _gc_stats = new CMSGCStats(); | |
226 | |
227 // Verify the assumption that FreeChunk::_prev and OopDesc::_klass | |
228 // offsets match. The ability to tell free chunks from objects | |
229 // depends on this property. | |
230 debug_only( | |
231 FreeChunk* junk = NULL; | |
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232 assert(UseCompressedKlassPointers || |
187 | 233 junk->prev_addr() == (void*)(oop(junk)->klass_addr()), |
0 | 234 "Offset of FreeChunk::_prev within FreeChunk must match" |
235 " that of OopDesc::_klass within OopDesc"); | |
236 ) | |
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237 if (CollectedHeap::use_parallel_gc_threads()) { |
0 | 238 typedef CMSParGCThreadState* CMSParGCThreadStatePtr; |
239 _par_gc_thread_states = | |
6197 | 240 NEW_C_HEAP_ARRAY(CMSParGCThreadStatePtr, ParallelGCThreads, mtGC); |
0 | 241 if (_par_gc_thread_states == NULL) { |
242 vm_exit_during_initialization("Could not allocate par gc structs"); | |
243 } | |
244 for (uint i = 0; i < ParallelGCThreads; i++) { | |
245 _par_gc_thread_states[i] = new CMSParGCThreadState(cmsSpace()); | |
246 if (_par_gc_thread_states[i] == NULL) { | |
247 vm_exit_during_initialization("Could not allocate par gc structs"); | |
248 } | |
249 } | |
250 } else { | |
251 _par_gc_thread_states = NULL; | |
252 } | |
253 _incremental_collection_failed = false; | |
254 // The "dilatation_factor" is the expansion that can occur on | |
255 // account of the fact that the minimum object size in the CMS | |
256 // generation may be larger than that in, say, a contiguous young | |
257 // generation. | |
258 // Ideally, in the calculation below, we'd compute the dilatation | |
259 // factor as: MinChunkSize/(promoting_gen's min object size) | |
260 // Since we do not have such a general query interface for the | |
261 // promoting generation, we'll instead just use the mimimum | |
262 // object size (which today is a header's worth of space); | |
263 // note that all arithmetic is in units of HeapWords. | |
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264 assert(MinChunkSize >= CollectedHeap::min_fill_size(), "just checking"); |
0 | 265 assert(_dilatation_factor >= 1.0, "from previous assert"); |
266 } | |
267 | |
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268 |
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269 // The field "_initiating_occupancy" represents the occupancy percentage |
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270 // at which we trigger a new collection cycle. Unless explicitly specified |
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271 // via CMSInitiatingOccupancyFraction (argument "io" below), it |
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272 // is calculated by: |
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273 // |
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274 // Let "f" be MinHeapFreeRatio in |
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275 // |
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276 // _intiating_occupancy = 100-f + |
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277 // f * (CMSTriggerRatio/100) |
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278 // where CMSTriggerRatio is the argument "tr" below. |
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279 // |
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280 // That is, if we assume the heap is at its desired maximum occupancy at the |
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281 // end of a collection, we let CMSTriggerRatio of the (purported) free |
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282 // space be allocated before initiating a new collection cycle. |
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283 // |
8035 | 284 void ConcurrentMarkSweepGeneration::init_initiating_occupancy(intx io, uintx tr) { |
285 assert(io <= 100 && tr <= 100, "Check the arguments"); | |
94
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286 if (io >= 0) { |
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287 _initiating_occupancy = (double)io / 100.0; |
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288 } else { |
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289 _initiating_occupancy = ((100 - MinHeapFreeRatio) + |
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290 (double)(tr * MinHeapFreeRatio) / 100.0) |
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291 / 100.0; |
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292 } |
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293 } |
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294 |
0 | 295 void ConcurrentMarkSweepGeneration::ref_processor_init() { |
296 assert(collector() != NULL, "no collector"); | |
297 collector()->ref_processor_init(); | |
298 } | |
299 | |
300 void CMSCollector::ref_processor_init() { | |
301 if (_ref_processor == NULL) { | |
302 // Allocate and initialize a reference processor | |
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303 _ref_processor = |
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304 new ReferenceProcessor(_span, // span |
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305 (ParallelGCThreads > 1) && ParallelRefProcEnabled, // mt processing |
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306 (int) ParallelGCThreads, // mt processing degree |
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307 _cmsGen->refs_discovery_is_mt(), // mt discovery |
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308 (int) MAX2(ConcGCThreads, ParallelGCThreads), // mt discovery degree |
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309 _cmsGen->refs_discovery_is_atomic(), // discovery is not atomic |
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310 &_is_alive_closure, // closure for liveness info |
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311 false); // next field updates do not need write barrier |
0 | 312 // Initialize the _ref_processor field of CMSGen |
313 _cmsGen->set_ref_processor(_ref_processor); | |
314 | |
315 } | |
316 } | |
317 | |
318 CMSAdaptiveSizePolicy* CMSCollector::size_policy() { | |
319 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
320 assert(gch->kind() == CollectedHeap::GenCollectedHeap, | |
321 "Wrong type of heap"); | |
322 CMSAdaptiveSizePolicy* sp = (CMSAdaptiveSizePolicy*) | |
323 gch->gen_policy()->size_policy(); | |
324 assert(sp->is_gc_cms_adaptive_size_policy(), | |
325 "Wrong type of size policy"); | |
326 return sp; | |
327 } | |
328 | |
329 CMSGCAdaptivePolicyCounters* CMSCollector::gc_adaptive_policy_counters() { | |
330 CMSGCAdaptivePolicyCounters* results = | |
331 (CMSGCAdaptivePolicyCounters*) collector_policy()->counters(); | |
332 assert( | |
333 results->kind() == GCPolicyCounters::CMSGCAdaptivePolicyCountersKind, | |
334 "Wrong gc policy counter kind"); | |
335 return results; | |
336 } | |
337 | |
338 | |
339 void ConcurrentMarkSweepGeneration::initialize_performance_counters() { | |
340 | |
341 const char* gen_name = "old"; | |
342 | |
343 // Generation Counters - generation 1, 1 subspace | |
344 _gen_counters = new GenerationCounters(gen_name, 1, 1, &_virtual_space); | |
345 | |
346 _space_counters = new GSpaceCounters(gen_name, 0, | |
347 _virtual_space.reserved_size(), | |
348 this, _gen_counters); | |
349 } | |
350 | |
351 CMSStats::CMSStats(ConcurrentMarkSweepGeneration* cms_gen, unsigned int alpha): | |
352 _cms_gen(cms_gen) | |
353 { | |
354 assert(alpha <= 100, "bad value"); | |
355 _saved_alpha = alpha; | |
356 | |
357 // Initialize the alphas to the bootstrap value of 100. | |
358 _gc0_alpha = _cms_alpha = 100; | |
359 | |
360 _cms_begin_time.update(); | |
361 _cms_end_time.update(); | |
362 | |
363 _gc0_duration = 0.0; | |
364 _gc0_period = 0.0; | |
365 _gc0_promoted = 0; | |
366 | |
367 _cms_duration = 0.0; | |
368 _cms_period = 0.0; | |
369 _cms_allocated = 0; | |
370 | |
371 _cms_used_at_gc0_begin = 0; | |
372 _cms_used_at_gc0_end = 0; | |
373 _allow_duty_cycle_reduction = false; | |
374 _valid_bits = 0; | |
375 _icms_duty_cycle = CMSIncrementalDutyCycle; | |
376 } | |
377 | |
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378 double CMSStats::cms_free_adjustment_factor(size_t free) const { |
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379 // TBD: CR 6909490 |
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380 return 1.0; |
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381 } |
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382 |
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383 void CMSStats::adjust_cms_free_adjustment_factor(bool fail, size_t free) { |
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384 } |
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385 |
0 | 386 // If promotion failure handling is on use |
387 // the padded average size of the promotion for each | |
388 // young generation collection. | |
389 double CMSStats::time_until_cms_gen_full() const { | |
390 size_t cms_free = _cms_gen->cmsSpace()->free(); | |
391 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
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392 size_t expected_promotion = MIN2(gch->get_gen(0)->capacity(), |
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393 (size_t) _cms_gen->gc_stats()->avg_promoted()->padded_average()); |
0 | 394 if (cms_free > expected_promotion) { |
395 // Start a cms collection if there isn't enough space to promote | |
396 // for the next minor collection. Use the padded average as | |
397 // a safety factor. | |
398 cms_free -= expected_promotion; | |
399 | |
400 // Adjust by the safety factor. | |
401 double cms_free_dbl = (double)cms_free; | |
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402 double cms_adjustment = (100.0 - CMSIncrementalSafetyFactor)/100.0; |
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403 // Apply a further correction factor which tries to adjust |
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404 // for recent occurance of concurrent mode failures. |
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405 cms_adjustment = cms_adjustment * cms_free_adjustment_factor(cms_free); |
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406 cms_free_dbl = cms_free_dbl * cms_adjustment; |
0 | 407 |
408 if (PrintGCDetails && Verbose) { | |
409 gclog_or_tty->print_cr("CMSStats::time_until_cms_gen_full: cms_free " | |
410 SIZE_FORMAT " expected_promotion " SIZE_FORMAT, | |
411 cms_free, expected_promotion); | |
412 gclog_or_tty->print_cr(" cms_free_dbl %f cms_consumption_rate %f", | |
413 cms_free_dbl, cms_consumption_rate() + 1.0); | |
414 } | |
415 // Add 1 in case the consumption rate goes to zero. | |
416 return cms_free_dbl / (cms_consumption_rate() + 1.0); | |
417 } | |
418 return 0.0; | |
419 } | |
420 | |
421 // Compare the duration of the cms collection to the | |
422 // time remaining before the cms generation is empty. | |
423 // Note that the time from the start of the cms collection | |
424 // to the start of the cms sweep (less than the total | |
425 // duration of the cms collection) can be used. This | |
426 // has been tried and some applications experienced | |
427 // promotion failures early in execution. This was | |
428 // possibly because the averages were not accurate | |
429 // enough at the beginning. | |
430 double CMSStats::time_until_cms_start() const { | |
431 // We add "gc0_period" to the "work" calculation | |
432 // below because this query is done (mostly) at the | |
433 // end of a scavenge, so we need to conservatively | |
434 // account for that much possible delay | |
435 // in the query so as to avoid concurrent mode failures | |
436 // due to starting the collection just a wee bit too | |
437 // late. | |
438 double work = cms_duration() + gc0_period(); | |
439 double deadline = time_until_cms_gen_full(); | |
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440 // If a concurrent mode failure occurred recently, we want to be |
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441 // more conservative and halve our expected time_until_cms_gen_full() |
0 | 442 if (work > deadline) { |
443 if (Verbose && PrintGCDetails) { | |
444 gclog_or_tty->print( | |
445 " CMSCollector: collect because of anticipated promotion " | |
446 "before full %3.7f + %3.7f > %3.7f ", cms_duration(), | |
447 gc0_period(), time_until_cms_gen_full()); | |
448 } | |
449 return 0.0; | |
450 } | |
451 return work - deadline; | |
452 } | |
453 | |
454 // Return a duty cycle based on old_duty_cycle and new_duty_cycle, limiting the | |
455 // amount of change to prevent wild oscillation. | |
456 unsigned int CMSStats::icms_damped_duty_cycle(unsigned int old_duty_cycle, | |
457 unsigned int new_duty_cycle) { | |
458 assert(old_duty_cycle <= 100, "bad input value"); | |
459 assert(new_duty_cycle <= 100, "bad input value"); | |
460 | |
461 // Note: use subtraction with caution since it may underflow (values are | |
462 // unsigned). Addition is safe since we're in the range 0-100. | |
463 unsigned int damped_duty_cycle = new_duty_cycle; | |
464 if (new_duty_cycle < old_duty_cycle) { | |
465 const unsigned int largest_delta = MAX2(old_duty_cycle / 4, 5U); | |
466 if (new_duty_cycle + largest_delta < old_duty_cycle) { | |
467 damped_duty_cycle = old_duty_cycle - largest_delta; | |
468 } | |
469 } else if (new_duty_cycle > old_duty_cycle) { | |
470 const unsigned int largest_delta = MAX2(old_duty_cycle / 4, 15U); | |
471 if (new_duty_cycle > old_duty_cycle + largest_delta) { | |
472 damped_duty_cycle = MIN2(old_duty_cycle + largest_delta, 100U); | |
473 } | |
474 } | |
475 assert(damped_duty_cycle <= 100, "invalid duty cycle computed"); | |
476 | |
477 if (CMSTraceIncrementalPacing) { | |
478 gclog_or_tty->print(" [icms_damped_duty_cycle(%d,%d) = %d] ", | |
479 old_duty_cycle, new_duty_cycle, damped_duty_cycle); | |
480 } | |
481 return damped_duty_cycle; | |
482 } | |
483 | |
484 unsigned int CMSStats::icms_update_duty_cycle_impl() { | |
485 assert(CMSIncrementalPacing && valid(), | |
486 "should be handled in icms_update_duty_cycle()"); | |
487 | |
488 double cms_time_so_far = cms_timer().seconds(); | |
489 double scaled_duration = cms_duration_per_mb() * _cms_used_at_gc0_end / M; | |
490 double scaled_duration_remaining = fabsd(scaled_duration - cms_time_so_far); | |
491 | |
492 // Avoid division by 0. | |
493 double time_until_full = MAX2(time_until_cms_gen_full(), 0.01); | |
494 double duty_cycle_dbl = 100.0 * scaled_duration_remaining / time_until_full; | |
495 | |
496 unsigned int new_duty_cycle = MIN2((unsigned int)duty_cycle_dbl, 100U); | |
497 if (new_duty_cycle > _icms_duty_cycle) { | |
498 // Avoid very small duty cycles (1 or 2); 0 is allowed. | |
499 if (new_duty_cycle > 2) { | |
500 _icms_duty_cycle = icms_damped_duty_cycle(_icms_duty_cycle, | |
501 new_duty_cycle); | |
502 } | |
503 } else if (_allow_duty_cycle_reduction) { | |
504 // The duty cycle is reduced only once per cms cycle (see record_cms_end()). | |
505 new_duty_cycle = icms_damped_duty_cycle(_icms_duty_cycle, new_duty_cycle); | |
506 // Respect the minimum duty cycle. | |
507 unsigned int min_duty_cycle = (unsigned int)CMSIncrementalDutyCycleMin; | |
508 _icms_duty_cycle = MAX2(new_duty_cycle, min_duty_cycle); | |
509 } | |
510 | |
511 if (PrintGCDetails || CMSTraceIncrementalPacing) { | |
512 gclog_or_tty->print(" icms_dc=%d ", _icms_duty_cycle); | |
513 } | |
514 | |
515 _allow_duty_cycle_reduction = false; | |
516 return _icms_duty_cycle; | |
517 } | |
518 | |
519 #ifndef PRODUCT | |
520 void CMSStats::print_on(outputStream *st) const { | |
521 st->print(" gc0_alpha=%d,cms_alpha=%d", _gc0_alpha, _cms_alpha); | |
522 st->print(",gc0_dur=%g,gc0_per=%g,gc0_promo=" SIZE_FORMAT, | |
523 gc0_duration(), gc0_period(), gc0_promoted()); | |
524 st->print(",cms_dur=%g,cms_dur_per_mb=%g,cms_per=%g,cms_alloc=" SIZE_FORMAT, | |
525 cms_duration(), cms_duration_per_mb(), | |
526 cms_period(), cms_allocated()); | |
527 st->print(",cms_since_beg=%g,cms_since_end=%g", | |
528 cms_time_since_begin(), cms_time_since_end()); | |
529 st->print(",cms_used_beg=" SIZE_FORMAT ",cms_used_end=" SIZE_FORMAT, | |
530 _cms_used_at_gc0_begin, _cms_used_at_gc0_end); | |
531 if (CMSIncrementalMode) { | |
532 st->print(",dc=%d", icms_duty_cycle()); | |
533 } | |
534 | |
535 if (valid()) { | |
536 st->print(",promo_rate=%g,cms_alloc_rate=%g", | |
537 promotion_rate(), cms_allocation_rate()); | |
538 st->print(",cms_consumption_rate=%g,time_until_full=%g", | |
539 cms_consumption_rate(), time_until_cms_gen_full()); | |
540 } | |
541 st->print(" "); | |
542 } | |
543 #endif // #ifndef PRODUCT | |
544 | |
545 CMSCollector::CollectorState CMSCollector::_collectorState = | |
546 CMSCollector::Idling; | |
547 bool CMSCollector::_foregroundGCIsActive = false; | |
548 bool CMSCollector::_foregroundGCShouldWait = false; | |
549 | |
550 CMSCollector::CMSCollector(ConcurrentMarkSweepGeneration* cmsGen, | |
551 CardTableRS* ct, | |
552 ConcurrentMarkSweepPolicy* cp): | |
553 _cmsGen(cmsGen), | |
554 _ct(ct), | |
555 _ref_processor(NULL), // will be set later | |
556 _conc_workers(NULL), // may be set later | |
557 _abort_preclean(false), | |
558 _start_sampling(false), | |
559 _between_prologue_and_epilogue(false), | |
560 _markBitMap(0, Mutex::leaf + 1, "CMS_markBitMap_lock"), | |
561 _modUnionTable((CardTableModRefBS::card_shift - LogHeapWordSize), | |
562 -1 /* lock-free */, "No_lock" /* dummy */), | |
563 _modUnionClosure(&_modUnionTable), | |
564 _modUnionClosurePar(&_modUnionTable), | |
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565 // Adjust my span to cover old (cms) gen |
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566 _span(cmsGen->reserved()), |
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567 // Construct the is_alive_closure with _span & markBitMap |
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568 _is_alive_closure(_span, &_markBitMap), |
0 | 569 _restart_addr(NULL), |
570 _overflow_list(NULL), | |
571 _stats(cmsGen), | |
572 _eden_chunk_array(NULL), // may be set in ctor body | |
573 _eden_chunk_capacity(0), // -- ditto -- | |
574 _eden_chunk_index(0), // -- ditto -- | |
575 _survivor_plab_array(NULL), // -- ditto -- | |
576 _survivor_chunk_array(NULL), // -- ditto -- | |
577 _survivor_chunk_capacity(0), // -- ditto -- | |
578 _survivor_chunk_index(0), // -- ditto -- | |
579 _ser_pmc_preclean_ovflw(0), | |
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580 _ser_kac_preclean_ovflw(0), |
0 | 581 _ser_pmc_remark_ovflw(0), |
582 _par_pmc_remark_ovflw(0), | |
583 _ser_kac_ovflw(0), | |
584 _par_kac_ovflw(0), | |
585 #ifndef PRODUCT | |
586 _num_par_pushes(0), | |
587 #endif | |
588 _collection_count_start(0), | |
589 _verifying(false), | |
590 _icms_start_limit(NULL), | |
591 _icms_stop_limit(NULL), | |
592 _verification_mark_bm(0, Mutex::leaf + 1, "CMS_verification_mark_bm_lock"), | |
593 _completed_initialization(false), | |
594 _collector_policy(cp), | |
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595 _should_unload_classes(false), |
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596 _concurrent_cycles_since_last_unload(0), |
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597 _roots_scanning_options(0), |
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598 _inter_sweep_estimate(CMS_SweepWeight, CMS_SweepPadding), |
10405 | 599 _intra_sweep_estimate(CMS_SweepWeight, CMS_SweepPadding), |
600 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) CMSTracer()), | |
601 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), | |
602 _cms_start_registered(false) | |
0 | 603 { |
604 if (ExplicitGCInvokesConcurrentAndUnloadsClasses) { | |
605 ExplicitGCInvokesConcurrent = true; | |
606 } | |
607 // Now expand the span and allocate the collection support structures | |
608 // (MUT, marking bit map etc.) to cover both generations subject to | |
609 // collection. | |
610 | |
611 // For use by dirty card to oop closures. | |
612 _cmsGen->cmsSpace()->set_collector(this); | |
613 | |
614 // Allocate MUT and marking bit map | |
615 { | |
616 MutexLockerEx x(_markBitMap.lock(), Mutex::_no_safepoint_check_flag); | |
617 if (!_markBitMap.allocate(_span)) { | |
618 warning("Failed to allocate CMS Bit Map"); | |
619 return; | |
620 } | |
621 assert(_markBitMap.covers(_span), "_markBitMap inconsistency?"); | |
622 } | |
623 { | |
624 _modUnionTable.allocate(_span); | |
625 assert(_modUnionTable.covers(_span), "_modUnionTable inconsistency?"); | |
626 } | |
627 | |
1284 | 628 if (!_markStack.allocate(MarkStackSize)) { |
0 | 629 warning("Failed to allocate CMS Marking Stack"); |
630 return; | |
631 } | |
632 | |
633 // Support for multi-threaded concurrent phases | |
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634 if (CMSConcurrentMTEnabled) { |
1284 | 635 if (FLAG_IS_DEFAULT(ConcGCThreads)) { |
0 | 636 // just for now |
1284 | 637 FLAG_SET_DEFAULT(ConcGCThreads, (ParallelGCThreads + 3)/4); |
638 } | |
639 if (ConcGCThreads > 1) { | |
0 | 640 _conc_workers = new YieldingFlexibleWorkGang("Parallel CMS Threads", |
1284 | 641 ConcGCThreads, true); |
0 | 642 if (_conc_workers == NULL) { |
643 warning("GC/CMS: _conc_workers allocation failure: " | |
644 "forcing -CMSConcurrentMTEnabled"); | |
645 CMSConcurrentMTEnabled = false; | |
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646 } else { |
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647 _conc_workers->initialize_workers(); |
0 | 648 } |
649 } else { | |
650 CMSConcurrentMTEnabled = false; | |
651 } | |
652 } | |
653 if (!CMSConcurrentMTEnabled) { | |
1284 | 654 ConcGCThreads = 0; |
0 | 655 } else { |
656 // Turn off CMSCleanOnEnter optimization temporarily for | |
657 // the MT case where it's not fixed yet; see 6178663. | |
658 CMSCleanOnEnter = false; | |
659 } | |
1284 | 660 assert((_conc_workers != NULL) == (ConcGCThreads > 1), |
0 | 661 "Inconsistency"); |
662 | |
663 // Parallel task queues; these are shared for the | |
664 // concurrent and stop-world phases of CMS, but | |
665 // are not shared with parallel scavenge (ParNew). | |
666 { | |
667 uint i; | |
1284 | 668 uint num_queues = (uint) MAX2(ParallelGCThreads, ConcGCThreads); |
0 | 669 |
670 if ((CMSParallelRemarkEnabled || CMSConcurrentMTEnabled | |
671 || ParallelRefProcEnabled) | |
672 && num_queues > 0) { | |
673 _task_queues = new OopTaskQueueSet(num_queues); | |
674 if (_task_queues == NULL) { | |
675 warning("task_queues allocation failure."); | |
676 return; | |
677 } | |
6197 | 678 _hash_seed = NEW_C_HEAP_ARRAY(int, num_queues, mtGC); |
0 | 679 if (_hash_seed == NULL) { |
680 warning("_hash_seed array allocation failure"); | |
681 return; | |
682 } | |
683 | |
1665 | 684 typedef Padded<OopTaskQueue> PaddedOopTaskQueue; |
0 | 685 for (i = 0; i < num_queues; i++) { |
1665 | 686 PaddedOopTaskQueue *q = new PaddedOopTaskQueue(); |
687 if (q == NULL) { | |
0 | 688 warning("work_queue allocation failure."); |
689 return; | |
690 } | |
1665 | 691 _task_queues->register_queue(i, q); |
0 | 692 } |
693 for (i = 0; i < num_queues; i++) { | |
694 _task_queues->queue(i)->initialize(); | |
695 _hash_seed[i] = 17; // copied from ParNew | |
696 } | |
697 } | |
698 } | |
699 | |
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700 _cmsGen ->init_initiating_occupancy(CMSInitiatingOccupancyFraction, CMSTriggerRatio); |
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701 |
0 | 702 // Clip CMSBootstrapOccupancy between 0 and 100. |
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703 _bootstrap_occupancy = ((double)CMSBootstrapOccupancy)/(double)100; |
0 | 704 |
705 _full_gcs_since_conc_gc = 0; | |
706 | |
707 // Now tell CMS generations the identity of their collector | |
708 ConcurrentMarkSweepGeneration::set_collector(this); | |
709 | |
710 // Create & start a CMS thread for this CMS collector | |
711 _cmsThread = ConcurrentMarkSweepThread::start(this); | |
712 assert(cmsThread() != NULL, "CMS Thread should have been created"); | |
713 assert(cmsThread()->collector() == this, | |
714 "CMS Thread should refer to this gen"); | |
715 assert(CGC_lock != NULL, "Where's the CGC_lock?"); | |
716 | |
717 // Support for parallelizing young gen rescan | |
718 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
719 _young_gen = gch->prev_gen(_cmsGen); | |
720 if (gch->supports_inline_contig_alloc()) { | |
721 _top_addr = gch->top_addr(); | |
722 _end_addr = gch->end_addr(); | |
723 assert(_young_gen != NULL, "no _young_gen"); | |
724 _eden_chunk_index = 0; | |
725 _eden_chunk_capacity = (_young_gen->max_capacity()+CMSSamplingGrain)/CMSSamplingGrain; | |
6197 | 726 _eden_chunk_array = NEW_C_HEAP_ARRAY(HeapWord*, _eden_chunk_capacity, mtGC); |
0 | 727 if (_eden_chunk_array == NULL) { |
728 _eden_chunk_capacity = 0; | |
729 warning("GC/CMS: _eden_chunk_array allocation failure"); | |
730 } | |
731 } | |
732 assert(_eden_chunk_array != NULL || _eden_chunk_capacity == 0, "Error"); | |
733 | |
734 // Support for parallelizing survivor space rescan | |
735 if (CMSParallelRemarkEnabled && CMSParallelSurvivorRemarkEnabled) { | |
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736 const size_t max_plab_samples = |
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737 ((DefNewGeneration*)_young_gen)->max_survivor_size()/MinTLABSize; |
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738 |
6197 | 739 _survivor_plab_array = NEW_C_HEAP_ARRAY(ChunkArray, ParallelGCThreads, mtGC); |
740 _survivor_chunk_array = NEW_C_HEAP_ARRAY(HeapWord*, 2*max_plab_samples, mtGC); | |
741 _cursor = NEW_C_HEAP_ARRAY(size_t, ParallelGCThreads, mtGC); | |
0 | 742 if (_survivor_plab_array == NULL || _survivor_chunk_array == NULL |
743 || _cursor == NULL) { | |
744 warning("Failed to allocate survivor plab/chunk array"); | |
745 if (_survivor_plab_array != NULL) { | |
6197 | 746 FREE_C_HEAP_ARRAY(ChunkArray, _survivor_plab_array, mtGC); |
0 | 747 _survivor_plab_array = NULL; |
748 } | |
749 if (_survivor_chunk_array != NULL) { | |
6197 | 750 FREE_C_HEAP_ARRAY(HeapWord*, _survivor_chunk_array, mtGC); |
0 | 751 _survivor_chunk_array = NULL; |
752 } | |
753 if (_cursor != NULL) { | |
6197 | 754 FREE_C_HEAP_ARRAY(size_t, _cursor, mtGC); |
0 | 755 _cursor = NULL; |
756 } | |
757 } else { | |
758 _survivor_chunk_capacity = 2*max_plab_samples; | |
759 for (uint i = 0; i < ParallelGCThreads; i++) { | |
6197 | 760 HeapWord** vec = NEW_C_HEAP_ARRAY(HeapWord*, max_plab_samples, mtGC); |
0 | 761 if (vec == NULL) { |
762 warning("Failed to allocate survivor plab array"); | |
763 for (int j = i; j > 0; j--) { | |
6197 | 764 FREE_C_HEAP_ARRAY(HeapWord*, _survivor_plab_array[j-1].array(), mtGC); |
0 | 765 } |
6197 | 766 FREE_C_HEAP_ARRAY(ChunkArray, _survivor_plab_array, mtGC); |
767 FREE_C_HEAP_ARRAY(HeapWord*, _survivor_chunk_array, mtGC); | |
0 | 768 _survivor_plab_array = NULL; |
769 _survivor_chunk_array = NULL; | |
770 _survivor_chunk_capacity = 0; | |
771 break; | |
772 } else { | |
773 ChunkArray* cur = | |
774 ::new (&_survivor_plab_array[i]) ChunkArray(vec, | |
775 max_plab_samples); | |
776 assert(cur->end() == 0, "Should be 0"); | |
777 assert(cur->array() == vec, "Should be vec"); | |
778 assert(cur->capacity() == max_plab_samples, "Error"); | |
779 } | |
780 } | |
781 } | |
782 } | |
783 assert( ( _survivor_plab_array != NULL | |
784 && _survivor_chunk_array != NULL) | |
785 || ( _survivor_chunk_capacity == 0 | |
786 && _survivor_chunk_index == 0), | |
787 "Error"); | |
788 | |
789 // Choose what strong roots should be scanned depending on verification options | |
790 if (!CMSClassUnloadingEnabled) { | |
791 // If class unloading is disabled we want to include all classes into the root set. | |
792 add_root_scanning_option(SharedHeap::SO_AllClasses); | |
793 } else { | |
794 add_root_scanning_option(SharedHeap::SO_SystemClasses); | |
795 } | |
796 | |
797 NOT_PRODUCT(_overflow_counter = CMSMarkStackOverflowInterval;) | |
798 _gc_counters = new CollectorCounters("CMS", 1); | |
799 _completed_initialization = true; | |
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800 _inter_sweep_timer.start(); // start of time |
0 | 801 } |
802 | |
803 const char* ConcurrentMarkSweepGeneration::name() const { | |
804 return "concurrent mark-sweep generation"; | |
805 } | |
806 void ConcurrentMarkSweepGeneration::update_counters() { | |
807 if (UsePerfData) { | |
808 _space_counters->update_all(); | |
809 _gen_counters->update_all(); | |
810 } | |
811 } | |
812 | |
813 // this is an optimized version of update_counters(). it takes the | |
814 // used value as a parameter rather than computing it. | |
815 // | |
816 void ConcurrentMarkSweepGeneration::update_counters(size_t used) { | |
817 if (UsePerfData) { | |
818 _space_counters->update_used(used); | |
819 _space_counters->update_capacity(); | |
820 _gen_counters->update_all(); | |
821 } | |
822 } | |
823 | |
824 void ConcurrentMarkSweepGeneration::print() const { | |
825 Generation::print(); | |
826 cmsSpace()->print(); | |
827 } | |
828 | |
829 #ifndef PRODUCT | |
830 void ConcurrentMarkSweepGeneration::print_statistics() { | |
831 cmsSpace()->printFLCensus(0); | |
832 } | |
833 #endif | |
834 | |
835 void ConcurrentMarkSweepGeneration::printOccupancy(const char *s) { | |
836 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
837 if (PrintGCDetails) { | |
838 if (Verbose) { | |
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839 gclog_or_tty->print("[%d %s-%s: "SIZE_FORMAT"("SIZE_FORMAT")]", |
0 | 840 level(), short_name(), s, used(), capacity()); |
841 } else { | |
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842 gclog_or_tty->print("[%d %s-%s: "SIZE_FORMAT"K("SIZE_FORMAT"K)]", |
0 | 843 level(), short_name(), s, used() / K, capacity() / K); |
844 } | |
845 } | |
846 if (Verbose) { | |
847 gclog_or_tty->print(" "SIZE_FORMAT"("SIZE_FORMAT")", | |
848 gch->used(), gch->capacity()); | |
849 } else { | |
850 gclog_or_tty->print(" "SIZE_FORMAT"K("SIZE_FORMAT"K)", | |
851 gch->used() / K, gch->capacity() / K); | |
852 } | |
853 } | |
854 | |
855 size_t | |
856 ConcurrentMarkSweepGeneration::contiguous_available() const { | |
857 // dld proposes an improvement in precision here. If the committed | |
858 // part of the space ends in a free block we should add that to | |
859 // uncommitted size in the calculation below. Will make this | |
860 // change later, staying with the approximation below for the | |
861 // time being. -- ysr. | |
862 return MAX2(_virtual_space.uncommitted_size(), unsafe_max_alloc_nogc()); | |
863 } | |
864 | |
865 size_t | |
866 ConcurrentMarkSweepGeneration::unsafe_max_alloc_nogc() const { | |
867 return _cmsSpace->max_alloc_in_words() * HeapWordSize; | |
868 } | |
869 | |
870 size_t ConcurrentMarkSweepGeneration::max_available() const { | |
871 return free() + _virtual_space.uncommitted_size(); | |
872 } | |
873 | |
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874 bool ConcurrentMarkSweepGeneration::promotion_attempt_is_safe(size_t max_promotion_in_bytes) const { |
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875 size_t available = max_available(); |
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876 size_t av_promo = (size_t)gc_stats()->avg_promoted()->padded_average(); |
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877 bool res = (available >= av_promo) || (available >= max_promotion_in_bytes); |
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878 if (Verbose && PrintGCDetails) { |
1888
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879 gclog_or_tty->print_cr( |
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880 "CMS: promo attempt is%s safe: available("SIZE_FORMAT") %s av_promo("SIZE_FORMAT")," |
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881 "max_promo("SIZE_FORMAT")", |
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882 res? "":" not", available, res? ">=":"<", |
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883 av_promo, max_promotion_in_bytes); |
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884 } |
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885 return res; |
0 | 886 } |
887 | |
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888 // At a promotion failure dump information on block layout in heap |
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889 // (cms old generation). |
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890 void ConcurrentMarkSweepGeneration::promotion_failure_occurred() { |
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891 if (CMSDumpAtPromotionFailure) { |
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892 cmsSpace()->dump_at_safepoint_with_locks(collector(), gclog_or_tty); |
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893 } |
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894 } |
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895 |
0 | 896 CompactibleSpace* |
897 ConcurrentMarkSweepGeneration::first_compaction_space() const { | |
898 return _cmsSpace; | |
899 } | |
900 | |
901 void ConcurrentMarkSweepGeneration::reset_after_compaction() { | |
902 // Clear the promotion information. These pointers can be adjusted | |
903 // along with all the other pointers into the heap but | |
904 // compaction is expected to be a rare event with | |
905 // a heap using cms so don't do it without seeing the need. | |
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906 if (CollectedHeap::use_parallel_gc_threads()) { |
0 | 907 for (uint i = 0; i < ParallelGCThreads; i++) { |
908 _par_gc_thread_states[i]->promo.reset(); | |
909 } | |
910 } | |
911 } | |
912 | |
913 void ConcurrentMarkSweepGeneration::space_iterate(SpaceClosure* blk, bool usedOnly) { | |
914 blk->do_space(_cmsSpace); | |
915 } | |
916 | |
917 void ConcurrentMarkSweepGeneration::compute_new_size() { | |
918 assert_locked_or_safepoint(Heap_lock); | |
919 | |
920 // If incremental collection failed, we just want to expand | |
921 // to the limit. | |
922 if (incremental_collection_failed()) { | |
923 clear_incremental_collection_failed(); | |
924 grow_to_reserved(); | |
925 return; | |
926 } | |
927 | |
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928 // The heap has been compacted but not reset yet. |
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929 // Any metric such as free() or used() will be incorrect. |
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930 |
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931 CardGeneration::compute_new_size(); |
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932 |
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933 // Reset again after a possible resizing |
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934 if (did_compact()) { |
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935 cmsSpace()->reset_after_compaction(); |
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936 } |
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937 } |
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938 |
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939 void ConcurrentMarkSweepGeneration::compute_new_size_free_list() { |
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940 assert_locked_or_safepoint(Heap_lock); |
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941 |
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942 // If incremental collection failed, we just want to expand |
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943 // to the limit. |
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944 if (incremental_collection_failed()) { |
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945 clear_incremental_collection_failed(); |
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946 grow_to_reserved(); |
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947 return; |
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948 } |
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949 |
0 | 950 double free_percentage = ((double) free()) / capacity(); |
951 double desired_free_percentage = (double) MinHeapFreeRatio / 100; | |
952 double maximum_free_percentage = (double) MaxHeapFreeRatio / 100; | |
953 | |
954 // compute expansion delta needed for reaching desired free percentage | |
955 if (free_percentage < desired_free_percentage) { | |
956 size_t desired_capacity = (size_t)(used() / ((double) 1 - desired_free_percentage)); | |
957 assert(desired_capacity >= capacity(), "invalid expansion size"); | |
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958 size_t expand_bytes = MAX2(desired_capacity - capacity(), MinHeapDeltaBytes); |
0 | 959 if (PrintGCDetails && Verbose) { |
960 size_t desired_capacity = (size_t)(used() / ((double) 1 - desired_free_percentage)); | |
961 gclog_or_tty->print_cr("\nFrom compute_new_size: "); | |
962 gclog_or_tty->print_cr(" Free fraction %f", free_percentage); | |
963 gclog_or_tty->print_cr(" Desired free fraction %f", | |
964 desired_free_percentage); | |
965 gclog_or_tty->print_cr(" Maximum free fraction %f", | |
966 maximum_free_percentage); | |
967 gclog_or_tty->print_cr(" Capactiy "SIZE_FORMAT, capacity()/1000); | |
968 gclog_or_tty->print_cr(" Desired capacity "SIZE_FORMAT, | |
969 desired_capacity/1000); | |
970 int prev_level = level() - 1; | |
971 if (prev_level >= 0) { | |
972 size_t prev_size = 0; | |
973 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
974 Generation* prev_gen = gch->_gens[prev_level]; | |
975 prev_size = prev_gen->capacity(); | |
976 gclog_or_tty->print_cr(" Younger gen size "SIZE_FORMAT, | |
977 prev_size/1000); | |
978 } | |
979 gclog_or_tty->print_cr(" unsafe_max_alloc_nogc "SIZE_FORMAT, | |
980 unsafe_max_alloc_nogc()/1000); | |
981 gclog_or_tty->print_cr(" contiguous available "SIZE_FORMAT, | |
982 contiguous_available()/1000); | |
983 gclog_or_tty->print_cr(" Expand by "SIZE_FORMAT" (bytes)", | |
984 expand_bytes); | |
985 } | |
986 // safe if expansion fails | |
987 expand(expand_bytes, 0, CMSExpansionCause::_satisfy_free_ratio); | |
988 if (PrintGCDetails && Verbose) { | |
989 gclog_or_tty->print_cr(" Expanded free fraction %f", | |
990 ((double) free()) / capacity()); | |
991 } | |
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992 } else { |
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993 size_t desired_capacity = (size_t)(used() / ((double) 1 - desired_free_percentage)); |
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994 assert(desired_capacity <= capacity(), "invalid expansion size"); |
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995 size_t shrink_bytes = capacity() - desired_capacity; |
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996 // Don't shrink unless the delta is greater than the minimum shrink we want |
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997 if (shrink_bytes >= MinHeapDeltaBytes) { |
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998 shrink_free_list_by(shrink_bytes); |
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999 } |
0 | 1000 } |
1001 } | |
1002 | |
1003 Mutex* ConcurrentMarkSweepGeneration::freelistLock() const { | |
1004 return cmsSpace()->freelistLock(); | |
1005 } | |
1006 | |
1007 HeapWord* ConcurrentMarkSweepGeneration::allocate(size_t size, | |
1008 bool tlab) { | |
1009 CMSSynchronousYieldRequest yr; | |
1010 MutexLockerEx x(freelistLock(), | |
1011 Mutex::_no_safepoint_check_flag); | |
1012 return have_lock_and_allocate(size, tlab); | |
1013 } | |
1014 | |
1015 HeapWord* ConcurrentMarkSweepGeneration::have_lock_and_allocate(size_t size, | |
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1016 bool tlab /* ignored */) { |
0 | 1017 assert_lock_strong(freelistLock()); |
1018 size_t adjustedSize = CompactibleFreeListSpace::adjustObjectSize(size); | |
1019 HeapWord* res = cmsSpace()->allocate(adjustedSize); | |
1020 // Allocate the object live (grey) if the background collector has | |
1021 // started marking. This is necessary because the marker may | |
1022 // have passed this address and consequently this object will | |
1023 // not otherwise be greyed and would be incorrectly swept up. | |
1024 // Note that if this object contains references, the writing | |
1025 // of those references will dirty the card containing this object | |
1026 // allowing the object to be blackened (and its references scanned) | |
1027 // either during a preclean phase or at the final checkpoint. | |
1028 if (res != NULL) { | |
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1029 // We may block here with an uninitialized object with |
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1030 // its mark-bit or P-bits not yet set. Such objects need |
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1031 // to be safely navigable by block_start(). |
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1032 assert(oop(res)->klass_or_null() == NULL, "Object should be uninitialized here."); |
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1033 assert(!((FreeChunk*)res)->is_free(), "Error, block will look free but show wrong size"); |
0 | 1034 collector()->direct_allocated(res, adjustedSize); |
1035 _direct_allocated_words += adjustedSize; | |
1036 // allocation counters | |
1037 NOT_PRODUCT( | |
1038 _numObjectsAllocated++; | |
1039 _numWordsAllocated += (int)adjustedSize; | |
1040 ) | |
1041 } | |
1042 return res; | |
1043 } | |
1044 | |
1045 // In the case of direct allocation by mutators in a generation that | |
1046 // is being concurrently collected, the object must be allocated | |
1047 // live (grey) if the background collector has started marking. | |
1048 // This is necessary because the marker may | |
1049 // have passed this address and consequently this object will | |
1050 // not otherwise be greyed and would be incorrectly swept up. | |
1051 // Note that if this object contains references, the writing | |
1052 // of those references will dirty the card containing this object | |
1053 // allowing the object to be blackened (and its references scanned) | |
1054 // either during a preclean phase or at the final checkpoint. | |
1055 void CMSCollector::direct_allocated(HeapWord* start, size_t size) { | |
1056 assert(_markBitMap.covers(start, size), "Out of bounds"); | |
1057 if (_collectorState >= Marking) { | |
1058 MutexLockerEx y(_markBitMap.lock(), | |
1059 Mutex::_no_safepoint_check_flag); | |
1060 // [see comments preceding SweepClosure::do_blk() below for details] | |
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1061 // |
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1062 // Can the P-bits be deleted now? JJJ |
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1063 // |
0 | 1064 // 1. need to mark the object as live so it isn't collected |
1065 // 2. need to mark the 2nd bit to indicate the object may be uninitialized | |
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1066 // 3. need to mark the end of the object so marking, precleaning or sweeping |
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1067 // can skip over uninitialized or unparsable objects. An allocated |
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1068 // object is considered uninitialized for our purposes as long as |
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1069 // its klass word is NULL. All old gen objects are parsable |
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1070 // as soon as they are initialized.) |
0 | 1071 _markBitMap.mark(start); // object is live |
1072 _markBitMap.mark(start + 1); // object is potentially uninitialized? | |
1073 _markBitMap.mark(start + size - 1); | |
1074 // mark end of object | |
1075 } | |
1076 // check that oop looks uninitialized | |
187 | 1077 assert(oop(start)->klass_or_null() == NULL, "_klass should be NULL"); |
0 | 1078 } |
1079 | |
1080 void CMSCollector::promoted(bool par, HeapWord* start, | |
1081 bool is_obj_array, size_t obj_size) { | |
1082 assert(_markBitMap.covers(start), "Out of bounds"); | |
1083 // See comment in direct_allocated() about when objects should | |
1084 // be allocated live. | |
1085 if (_collectorState >= Marking) { | |
1086 // we already hold the marking bit map lock, taken in | |
1087 // the prologue | |
1088 if (par) { | |
1089 _markBitMap.par_mark(start); | |
1090 } else { | |
1091 _markBitMap.mark(start); | |
1092 } | |
1093 // We don't need to mark the object as uninitialized (as | |
1094 // in direct_allocated above) because this is being done with the | |
1095 // world stopped and the object will be initialized by the | |
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1096 // time the marking, precleaning or sweeping get to look at it. |
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1097 // But see the code for copying objects into the CMS generation, |
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1098 // where we need to ensure that concurrent readers of the |
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1099 // block offset table are able to safely navigate a block that |
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1100 // is in flux from being free to being allocated (and in |
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1101 // transition while being copied into) and subsequently |
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1102 // becoming a bona-fide object when the copy/promotion is complete. |
0 | 1103 assert(SafepointSynchronize::is_at_safepoint(), |
1104 "expect promotion only at safepoints"); | |
1105 | |
1106 if (_collectorState < Sweeping) { | |
1107 // Mark the appropriate cards in the modUnionTable, so that | |
1108 // this object gets scanned before the sweep. If this is | |
1109 // not done, CMS generation references in the object might | |
1110 // not get marked. | |
1111 // For the case of arrays, which are otherwise precisely | |
1112 // marked, we need to dirty the entire array, not just its head. | |
1113 if (is_obj_array) { | |
1114 // The [par_]mark_range() method expects mr.end() below to | |
1115 // be aligned to the granularity of a bit's representation | |
1116 // in the heap. In the case of the MUT below, that's a | |
1117 // card size. | |
1118 MemRegion mr(start, | |
1119 (HeapWord*)round_to((intptr_t)(start + obj_size), | |
1120 CardTableModRefBS::card_size /* bytes */)); | |
1121 if (par) { | |
1122 _modUnionTable.par_mark_range(mr); | |
1123 } else { | |
1124 _modUnionTable.mark_range(mr); | |
1125 } | |
1126 } else { // not an obj array; we can just mark the head | |
1127 if (par) { | |
1128 _modUnionTable.par_mark(start); | |
1129 } else { | |
1130 _modUnionTable.mark(start); | |
1131 } | |
1132 } | |
1133 } | |
1134 } | |
1135 } | |
1136 | |
1137 static inline size_t percent_of_space(Space* space, HeapWord* addr) | |
1138 { | |
1139 size_t delta = pointer_delta(addr, space->bottom()); | |
1140 return (size_t)(delta * 100.0 / (space->capacity() / HeapWordSize)); | |
1141 } | |
1142 | |
1143 void CMSCollector::icms_update_allocation_limits() | |
1144 { | |
1145 Generation* gen0 = GenCollectedHeap::heap()->get_gen(0); | |
1146 EdenSpace* eden = gen0->as_DefNewGeneration()->eden(); | |
1147 | |
1148 const unsigned int duty_cycle = stats().icms_update_duty_cycle(); | |
1149 if (CMSTraceIncrementalPacing) { | |
1150 stats().print(); | |
1151 } | |
1152 | |
1153 assert(duty_cycle <= 100, "invalid duty cycle"); | |
1154 if (duty_cycle != 0) { | |
1155 // The duty_cycle is a percentage between 0 and 100; convert to words and | |
1156 // then compute the offset from the endpoints of the space. | |
1157 size_t free_words = eden->free() / HeapWordSize; | |
1158 double free_words_dbl = (double)free_words; | |
1159 size_t duty_cycle_words = (size_t)(free_words_dbl * duty_cycle / 100.0); | |
1160 size_t offset_words = (free_words - duty_cycle_words) / 2; | |
1161 | |
1162 _icms_start_limit = eden->top() + offset_words; | |
1163 _icms_stop_limit = eden->end() - offset_words; | |
1164 | |
1165 // The limits may be adjusted (shifted to the right) by | |
1166 // CMSIncrementalOffset, to allow the application more mutator time after a | |
1167 // young gen gc (when all mutators were stopped) and before CMS starts and | |
1168 // takes away one or more cpus. | |
1169 if (CMSIncrementalOffset != 0) { | |
1170 double adjustment_dbl = free_words_dbl * CMSIncrementalOffset / 100.0; | |
1171 size_t adjustment = (size_t)adjustment_dbl; | |
1172 HeapWord* tmp_stop = _icms_stop_limit + adjustment; | |
1173 if (tmp_stop > _icms_stop_limit && tmp_stop < eden->end()) { | |
1174 _icms_start_limit += adjustment; | |
1175 _icms_stop_limit = tmp_stop; | |
1176 } | |
1177 } | |
1178 } | |
1179 if (duty_cycle == 0 || (_icms_start_limit == _icms_stop_limit)) { | |
1180 _icms_start_limit = _icms_stop_limit = eden->end(); | |
1181 } | |
1182 | |
1183 // Install the new start limit. | |
1184 eden->set_soft_end(_icms_start_limit); | |
1185 | |
1186 if (CMSTraceIncrementalMode) { | |
1187 gclog_or_tty->print(" icms alloc limits: " | |
1188 PTR_FORMAT "," PTR_FORMAT | |
1189 " (" SIZE_FORMAT "%%," SIZE_FORMAT "%%) ", | |
1190 _icms_start_limit, _icms_stop_limit, | |
1191 percent_of_space(eden, _icms_start_limit), | |
1192 percent_of_space(eden, _icms_stop_limit)); | |
1193 if (Verbose) { | |
1194 gclog_or_tty->print("eden: "); | |
1195 eden->print_on(gclog_or_tty); | |
1196 } | |
1197 } | |
1198 } | |
1199 | |
1200 // Any changes here should try to maintain the invariant | |
1201 // that if this method is called with _icms_start_limit | |
1202 // and _icms_stop_limit both NULL, then it should return NULL | |
1203 // and not notify the icms thread. | |
1204 HeapWord* | |
1205 CMSCollector::allocation_limit_reached(Space* space, HeapWord* top, | |
1206 size_t word_size) | |
1207 { | |
1208 // A start_limit equal to end() means the duty cycle is 0, so treat that as a | |
1209 // nop. | |
1210 if (CMSIncrementalMode && _icms_start_limit != space->end()) { | |
1211 if (top <= _icms_start_limit) { | |
1212 if (CMSTraceIncrementalMode) { | |
1213 space->print_on(gclog_or_tty); | |
1214 gclog_or_tty->stamp(); | |
1215 gclog_or_tty->print_cr(" start limit top=" PTR_FORMAT | |
1216 ", new limit=" PTR_FORMAT | |
1217 " (" SIZE_FORMAT "%%)", | |
1218 top, _icms_stop_limit, | |
1219 percent_of_space(space, _icms_stop_limit)); | |
1220 } | |
1221 ConcurrentMarkSweepThread::start_icms(); | |
1222 assert(top < _icms_stop_limit, "Tautology"); | |
1223 if (word_size < pointer_delta(_icms_stop_limit, top)) { | |
1224 return _icms_stop_limit; | |
1225 } | |
1226 | |
1227 // The allocation will cross both the _start and _stop limits, so do the | |
1228 // stop notification also and return end(). | |
1229 if (CMSTraceIncrementalMode) { | |
1230 space->print_on(gclog_or_tty); | |
1231 gclog_or_tty->stamp(); | |
1232 gclog_or_tty->print_cr(" +stop limit top=" PTR_FORMAT | |
1233 ", new limit=" PTR_FORMAT | |
1234 " (" SIZE_FORMAT "%%)", | |
1235 top, space->end(), | |
1236 percent_of_space(space, space->end())); | |
1237 } | |
1238 ConcurrentMarkSweepThread::stop_icms(); | |
1239 return space->end(); | |
1240 } | |
1241 | |
1242 if (top <= _icms_stop_limit) { | |
1243 if (CMSTraceIncrementalMode) { | |
1244 space->print_on(gclog_or_tty); | |
1245 gclog_or_tty->stamp(); | |
1246 gclog_or_tty->print_cr(" stop limit top=" PTR_FORMAT | |
1247 ", new limit=" PTR_FORMAT | |
1248 " (" SIZE_FORMAT "%%)", | |
1249 top, space->end(), | |
1250 percent_of_space(space, space->end())); | |
1251 } | |
1252 ConcurrentMarkSweepThread::stop_icms(); | |
1253 return space->end(); | |
1254 } | |
1255 | |
1256 if (CMSTraceIncrementalMode) { | |
1257 space->print_on(gclog_or_tty); | |
1258 gclog_or_tty->stamp(); | |
1259 gclog_or_tty->print_cr(" end limit top=" PTR_FORMAT | |
1260 ", new limit=" PTR_FORMAT, | |
1261 top, NULL); | |
1262 } | |
1263 } | |
1264 | |
1265 return NULL; | |
1266 } | |
1267 | |
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1268 oop ConcurrentMarkSweepGeneration::promote(oop obj, size_t obj_size) { |
0 | 1269 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in"); |
1270 // allocate, copy and if necessary update promoinfo -- | |
1271 // delegate to underlying space. | |
1272 assert_lock_strong(freelistLock()); | |
1273 | |
1274 #ifndef PRODUCT | |
1275 if (Universe::heap()->promotion_should_fail()) { | |
1276 return NULL; | |
1277 } | |
1278 #endif // #ifndef PRODUCT | |
1279 | |
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1280 oop res = _cmsSpace->promote(obj, obj_size); |
0 | 1281 if (res == NULL) { |
1282 // expand and retry | |
1283 size_t s = _cmsSpace->expansionSpaceRequired(obj_size); // HeapWords | |
1284 expand(s*HeapWordSize, MinHeapDeltaBytes, | |
1285 CMSExpansionCause::_satisfy_promotion); | |
1286 // Since there's currently no next generation, we don't try to promote | |
1287 // into a more senior generation. | |
1288 assert(next_gen() == NULL, "assumption, based upon which no attempt " | |
1289 "is made to pass on a possibly failing " | |
1290 "promotion to next generation"); | |
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1291 res = _cmsSpace->promote(obj, obj_size); |
0 | 1292 } |
1293 if (res != NULL) { | |
1294 // See comment in allocate() about when objects should | |
1295 // be allocated live. | |
1296 assert(obj->is_oop(), "Will dereference klass pointer below"); | |
1297 collector()->promoted(false, // Not parallel | |
1298 (HeapWord*)res, obj->is_objArray(), obj_size); | |
1299 // promotion counters | |
1300 NOT_PRODUCT( | |
1301 _numObjectsPromoted++; | |
1302 _numWordsPromoted += | |
1303 (int)(CompactibleFreeListSpace::adjustObjectSize(obj->size())); | |
1304 ) | |
1305 } | |
1306 return res; | |
1307 } | |
1308 | |
1309 | |
1310 HeapWord* | |
1311 ConcurrentMarkSweepGeneration::allocation_limit_reached(Space* space, | |
1312 HeapWord* top, | |
1313 size_t word_sz) | |
1314 { | |
1315 return collector()->allocation_limit_reached(space, top, word_sz); | |
1316 } | |
1317 | |
1716
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1318 // IMPORTANT: Notes on object size recognition in CMS. |
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1319 // --------------------------------------------------- |
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1320 // A block of storage in the CMS generation is always in |
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1321 // one of three states. A free block (FREE), an allocated |
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1322 // object (OBJECT) whose size() method reports the correct size, |
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1323 // and an intermediate state (TRANSIENT) in which its size cannot |
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1324 // be accurately determined. |
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1325 // STATE IDENTIFICATION: (32 bit and 64 bit w/o COOPS) |
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1326 // ----------------------------------------------------- |
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1327 // FREE: klass_word & 1 == 1; mark_word holds block size |
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1328 // |
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1329 // OBJECT: klass_word installed; klass_word != 0 && klass_word & 1 == 0; |
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1330 // obj->size() computes correct size |
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1331 // |
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1332 // TRANSIENT: klass_word == 0; size is indeterminate until we become an OBJECT |
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1333 // |
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1334 // STATE IDENTIFICATION: (64 bit+COOPS) |
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1335 // ------------------------------------ |
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1336 // FREE: mark_word & CMS_FREE_BIT == 1; mark_word & ~CMS_FREE_BIT gives block_size |
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1337 // |
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1338 // OBJECT: klass_word installed; klass_word != 0; |
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1339 // obj->size() computes correct size |
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1340 // |
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1341 // TRANSIENT: klass_word == 0; size is indeterminate until we become an OBJECT |
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1342 // |
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1343 // |
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1344 // STATE TRANSITION DIAGRAM |
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1345 // |
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1346 // mut / parnew mut / parnew |
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1347 // FREE --------------------> TRANSIENT ---------------------> OBJECT --| |
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1348 // ^ | |
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1349 // |------------------------ DEAD <------------------------------------| |
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1350 // sweep mut |
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1351 // |
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1352 // While a block is in TRANSIENT state its size cannot be determined |
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1353 // so readers will either need to come back later or stall until |
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1354 // the size can be determined. Note that for the case of direct |
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1355 // allocation, P-bits, when available, may be used to determine the |
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1356 // size of an object that may not yet have been initialized. |
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1357 |
0 | 1358 // Things to support parallel young-gen collection. |
1359 oop | |
1360 ConcurrentMarkSweepGeneration::par_promote(int thread_num, | |
1361 oop old, markOop m, | |
1362 size_t word_sz) { | |
1363 #ifndef PRODUCT | |
1364 if (Universe::heap()->promotion_should_fail()) { | |
1365 return NULL; | |
1366 } | |
1367 #endif // #ifndef PRODUCT | |
1368 | |
1369 CMSParGCThreadState* ps = _par_gc_thread_states[thread_num]; | |
1370 PromotionInfo* promoInfo = &ps->promo; | |
1371 // if we are tracking promotions, then first ensure space for | |
1372 // promotion (including spooling space for saving header if necessary). | |
1373 // then allocate and copy, then track promoted info if needed. | |
1374 // When tracking (see PromotionInfo::track()), the mark word may | |
1375 // be displaced and in this case restoration of the mark word | |
1376 // occurs in the (oop_since_save_marks_)iterate phase. | |
1377 if (promoInfo->tracking() && !promoInfo->ensure_spooling_space()) { | |
1378 // Out of space for allocating spooling buffers; | |
1379 // try expanding and allocating spooling buffers. | |
1380 if (!expand_and_ensure_spooling_space(promoInfo)) { | |
1381 return NULL; | |
1382 } | |
1383 } | |
1384 assert(promoInfo->has_spooling_space(), "Control point invariant"); | |
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1385 const size_t alloc_sz = CompactibleFreeListSpace::adjustObjectSize(word_sz); |
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1386 HeapWord* obj_ptr = ps->lab.alloc(alloc_sz); |
0 | 1387 if (obj_ptr == NULL) { |
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1388 obj_ptr = expand_and_par_lab_allocate(ps, alloc_sz); |
0 | 1389 if (obj_ptr == NULL) { |
1390 return NULL; | |
1391 } | |
1392 } | |
1393 oop obj = oop(obj_ptr); | |
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1394 OrderAccess::storestore(); |
187 | 1395 assert(obj->klass_or_null() == NULL, "Object should be uninitialized here."); |
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1396 assert(!((FreeChunk*)obj_ptr)->is_free(), "Error, block will look free but show wrong size"); |
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1397 // IMPORTANT: See note on object initialization for CMS above. |
0 | 1398 // Otherwise, copy the object. Here we must be careful to insert the |
1399 // klass pointer last, since this marks the block as an allocated object. | |
187 | 1400 // Except with compressed oops it's the mark word. |
0 | 1401 HeapWord* old_ptr = (HeapWord*)old; |
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1402 // Restore the mark word copied above. |
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1403 obj->set_mark(m); |
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1404 assert(obj->klass_or_null() == NULL, "Object should be uninitialized here."); |
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1405 assert(!((FreeChunk*)obj_ptr)->is_free(), "Error, block will look free but show wrong size"); |
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1406 OrderAccess::storestore(); |
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1407 |
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1408 if (UseCompressedKlassPointers) { |
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1409 // Copy gap missed by (aligned) header size calculation below |
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1410 obj->set_klass_gap(old->klass_gap()); |
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1411 } |
0 | 1412 if (word_sz > (size_t)oopDesc::header_size()) { |
1413 Copy::aligned_disjoint_words(old_ptr + oopDesc::header_size(), | |
1414 obj_ptr + oopDesc::header_size(), | |
1415 word_sz - oopDesc::header_size()); | |
1416 } | |
187 | 1417 |
0 | 1418 // Now we can track the promoted object, if necessary. We take care |
1521 | 1419 // to delay the transition from uninitialized to full object |
0 | 1420 // (i.e., insertion of klass pointer) until after, so that it |
1421 // atomically becomes a promoted object. | |
1422 if (promoInfo->tracking()) { | |
1423 promoInfo->track((PromotedObject*)obj, old->klass()); | |
1424 } | |
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1425 assert(obj->klass_or_null() == NULL, "Object should be uninitialized here."); |
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1426 assert(!((FreeChunk*)obj_ptr)->is_free(), "Error, block will look free but show wrong size"); |
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1427 assert(old->is_oop(), "Will use and dereference old klass ptr below"); |
187 | 1428 |
1429 // Finally, install the klass pointer (this should be volatile). | |
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1430 OrderAccess::storestore(); |
0 | 1431 obj->set_klass(old->klass()); |
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1432 // We should now be able to calculate the right size for this object |
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1433 assert(obj->is_oop() && obj->size() == (int)word_sz, "Error, incorrect size computed for promoted object"); |
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1434 |
0 | 1435 collector()->promoted(true, // parallel |
1436 obj_ptr, old->is_objArray(), word_sz); | |
1437 | |
1438 NOT_PRODUCT( | |
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1439 Atomic::inc_ptr(&_numObjectsPromoted); |
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1440 Atomic::add_ptr(alloc_sz, &_numWordsPromoted); |
0 | 1441 ) |
1442 | |
1443 return obj; | |
1444 } | |
1445 | |
1446 void | |
1447 ConcurrentMarkSweepGeneration:: | |
1448 par_promote_alloc_undo(int thread_num, | |
1449 HeapWord* obj, size_t word_sz) { | |
1450 // CMS does not support promotion undo. | |
1451 ShouldNotReachHere(); | |
1452 } | |
1453 | |
1454 void | |
1455 ConcurrentMarkSweepGeneration:: | |
1456 par_promote_alloc_done(int thread_num) { | |
1457 CMSParGCThreadState* ps = _par_gc_thread_states[thread_num]; | |
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1458 ps->lab.retire(thread_num); |
0 | 1459 } |
1460 | |
1461 void | |
1462 ConcurrentMarkSweepGeneration:: | |
1463 par_oop_since_save_marks_iterate_done(int thread_num) { | |
1464 CMSParGCThreadState* ps = _par_gc_thread_states[thread_num]; | |
1465 ParScanWithoutBarrierClosure* dummy_cl = NULL; | |
1466 ps->promo.promoted_oops_iterate_nv(dummy_cl); | |
1467 } | |
1468 | |
1469 bool ConcurrentMarkSweepGeneration::should_collect(bool full, | |
1470 size_t size, | |
1471 bool tlab) | |
1472 { | |
1473 // We allow a STW collection only if a full | |
1474 // collection was requested. | |
1475 return full || should_allocate(size, tlab); // FIX ME !!! | |
1476 // This and promotion failure handling are connected at the | |
1477 // hip and should be fixed by untying them. | |
1478 } | |
1479 | |
1480 bool CMSCollector::shouldConcurrentCollect() { | |
1481 if (_full_gc_requested) { | |
1482 if (Verbose && PrintGCDetails) { | |
1483 gclog_or_tty->print_cr("CMSCollector: collect because of explicit " | |
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1484 " gc request (or gc_locker)"); |
0 | 1485 } |
1486 return true; | |
1487 } | |
1488 | |
1489 // For debugging purposes, change the type of collection. | |
1490 // If the rotation is not on the concurrent collection | |
1491 // type, don't start a concurrent collection. | |
1492 NOT_PRODUCT( | |
1493 if (RotateCMSCollectionTypes && | |
1494 (_cmsGen->debug_collection_type() != | |
1495 ConcurrentMarkSweepGeneration::Concurrent_collection_type)) { | |
1496 assert(_cmsGen->debug_collection_type() != | |
1497 ConcurrentMarkSweepGeneration::Unknown_collection_type, | |
1498 "Bad cms collection type"); | |
1499 return false; | |
1500 } | |
1501 ) | |
1502 | |
1503 FreelistLocker x(this); | |
1504 // ------------------------------------------------------------------ | |
1505 // Print out lots of information which affects the initiation of | |
1506 // a collection. | |
1507 if (PrintCMSInitiationStatistics && stats().valid()) { | |
1508 gclog_or_tty->print("CMSCollector shouldConcurrentCollect: "); | |
1509 gclog_or_tty->stamp(); | |
1510 gclog_or_tty->print_cr(""); | |
1511 stats().print_on(gclog_or_tty); | |
1512 gclog_or_tty->print_cr("time_until_cms_gen_full %3.7f", | |
1513 stats().time_until_cms_gen_full()); | |
1514 gclog_or_tty->print_cr("free="SIZE_FORMAT, _cmsGen->free()); | |
1515 gclog_or_tty->print_cr("contiguous_available="SIZE_FORMAT, | |
1516 _cmsGen->contiguous_available()); | |
1517 gclog_or_tty->print_cr("promotion_rate=%g", stats().promotion_rate()); | |
1518 gclog_or_tty->print_cr("cms_allocation_rate=%g", stats().cms_allocation_rate()); | |
1519 gclog_or_tty->print_cr("occupancy=%3.7f", _cmsGen->occupancy()); | |
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1520 gclog_or_tty->print_cr("initiatingOccupancy=%3.7f", _cmsGen->initiating_occupancy()); |
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1521 gclog_or_tty->print_cr("metadata initialized %d", |
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1522 MetaspaceGC::should_concurrent_collect()); |
0 | 1523 } |
1524 // ------------------------------------------------------------------ | |
1525 | |
1526 // If the estimated time to complete a cms collection (cms_duration()) | |
1527 // is less than the estimated time remaining until the cms generation | |
1528 // is full, start a collection. | |
1529 if (!UseCMSInitiatingOccupancyOnly) { | |
1530 if (stats().valid()) { | |
1531 if (stats().time_until_cms_start() == 0.0) { | |
1532 return true; | |
1533 } | |
1534 } else { | |
1535 // We want to conservatively collect somewhat early in order | |
1536 // to try and "bootstrap" our CMS/promotion statistics; | |
1537 // this branch will not fire after the first successful CMS | |
1538 // collection because the stats should then be valid. | |
1539 if (_cmsGen->occupancy() >= _bootstrap_occupancy) { | |
1540 if (Verbose && PrintGCDetails) { | |
1541 gclog_or_tty->print_cr( | |
1542 " CMSCollector: collect for bootstrapping statistics:" | |
1543 " occupancy = %f, boot occupancy = %f", _cmsGen->occupancy(), | |
1544 _bootstrap_occupancy); | |
1545 } | |
1546 return true; | |
1547 } | |
1548 } | |
1549 } | |
1550 | |
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1551 // Otherwise, we start a collection cycle if |
0 | 1552 // old gen want a collection cycle started. Each may use |
1553 // an appropriate criterion for making this decision. | |
1554 // XXX We need to make sure that the gen expansion | |
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1555 // criterion dovetails well with this. XXX NEED TO FIX THIS |
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1556 if (_cmsGen->should_concurrent_collect()) { |
0 | 1557 if (Verbose && PrintGCDetails) { |
1558 gclog_or_tty->print_cr("CMS old gen initiated"); | |
1559 } | |
1560 return true; | |
1561 } | |
1562 | |
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1563 // We start a collection if we believe an incremental collection may fail; |
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1564 // this is not likely to be productive in practice because it's probably too |
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1565 // late anyway. |
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1566 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
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1567 assert(gch->collector_policy()->is_two_generation_policy(), |
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1568 "You may want to check the correctness of the following"); |
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1569 if (gch->incremental_collection_will_fail(true /* consult_young */)) { |
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1570 if (Verbose && PrintGCDetails) { |
94
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1571 gclog_or_tty->print("CMSCollector: collect because incremental collection will fail "); |
0 | 1572 } |
1573 return true; | |
1574 } | |
1575 | |
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1576 if (MetaspaceGC::should_concurrent_collect()) { |
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1577 if (Verbose && PrintGCDetails) { |
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1578 gclog_or_tty->print("CMSCollector: collect for metadata allocation "); |
94
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1579 } |
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1580 return true; |
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1581 } |
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1582 |
0 | 1583 return false; |
1584 } | |
1585 | |
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1586 void CMSCollector::set_did_compact(bool v) { _cmsGen->set_did_compact(v); } |
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1587 |
0 | 1588 // Clear _expansion_cause fields of constituent generations |
1589 void CMSCollector::clear_expansion_cause() { | |
1590 _cmsGen->clear_expansion_cause(); | |
1591 } | |
1592 | |
94
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1593 // We should be conservative in starting a collection cycle. To |
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1594 // start too eagerly runs the risk of collecting too often in the |
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1595 // extreme. To collect too rarely falls back on full collections, |
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1596 // which works, even if not optimum in terms of concurrent work. |
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1597 // As a work around for too eagerly collecting, use the flag |
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1598 // UseCMSInitiatingOccupancyOnly. This also has the advantage of |
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1599 // giving the user an easily understandable way of controlling the |
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1600 // collections. |
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1601 // We want to start a new collection cycle if any of the following |
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1602 // conditions hold: |
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1603 // . our current occupancy exceeds the configured initiating occupancy |
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1604 // for this generation, or |
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1605 // . we recently needed to expand this space and have not, since that |
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1606 // expansion, done a collection of this generation, or |
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1607 // . the underlying space believes that it may be a good idea to initiate |
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1608 // a concurrent collection (this may be based on criteria such as the |
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1609 // following: the space uses linear allocation and linear allocation is |
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1610 // going to fail, or there is believed to be excessive fragmentation in |
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1611 // the generation, etc... or ... |
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1612 // [.(currently done by CMSCollector::shouldConcurrentCollect() only for |
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1613 // the case of the old generation; see CR 6543076): |
94
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1614 // we may be approaching a point at which allocation requests may fail because |
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1615 // we will be out of sufficient free space given allocation rate estimates.] |
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1616 bool ConcurrentMarkSweepGeneration::should_concurrent_collect() const { |
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1617 |
0 | 1618 assert_lock_strong(freelistLock()); |
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1619 if (occupancy() > initiating_occupancy()) { |
0 | 1620 if (PrintGCDetails && Verbose) { |
1621 gclog_or_tty->print(" %s: collect because of occupancy %f / %f ", | |
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1622 short_name(), occupancy(), initiating_occupancy()); |
0 | 1623 } |
1624 return true; | |
1625 } | |
1626 if (UseCMSInitiatingOccupancyOnly) { | |
1627 return false; | |
1628 } | |
1629 if (expansion_cause() == CMSExpansionCause::_satisfy_allocation) { | |
1630 if (PrintGCDetails && Verbose) { | |
1631 gclog_or_tty->print(" %s: collect because expanded for allocation ", | |
1632 short_name()); | |
1633 } | |
1634 return true; | |
1635 } | |
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1636 if (_cmsSpace->should_concurrent_collect()) { |
0 | 1637 if (PrintGCDetails && Verbose) { |
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1638 gclog_or_tty->print(" %s: collect because cmsSpace says so ", |
0 | 1639 short_name()); |
1640 } | |
1641 return true; | |
1642 } | |
1643 return false; | |
1644 } | |
1645 | |
1646 void ConcurrentMarkSweepGeneration::collect(bool full, | |
1647 bool clear_all_soft_refs, | |
1648 size_t size, | |
1649 bool tlab) | |
1650 { | |
1651 collector()->collect(full, clear_all_soft_refs, size, tlab); | |
1652 } | |
1653 | |
1654 void CMSCollector::collect(bool full, | |
1655 bool clear_all_soft_refs, | |
1656 size_t size, | |
1657 bool tlab) | |
1658 { | |
1659 if (!UseCMSCollectionPassing && _collectorState > Idling) { | |
1660 // For debugging purposes skip the collection if the state | |
1661 // is not currently idle | |
1662 if (TraceCMSState) { | |
1663 gclog_or_tty->print_cr("Thread " INTPTR_FORMAT " skipped full:%d CMS state %d", | |
1664 Thread::current(), full, _collectorState); | |
1665 } | |
1666 return; | |
1667 } | |
1668 | |
1669 // The following "if" branch is present for defensive reasons. | |
1670 // In the current uses of this interface, it can be replaced with: | |
1671 // assert(!GC_locker.is_active(), "Can't be called otherwise"); | |
1672 // But I am not placing that assert here to allow future | |
1673 // generality in invoking this interface. | |
1674 if (GC_locker::is_active()) { | |
1675 // A consistency test for GC_locker | |
1676 assert(GC_locker::needs_gc(), "Should have been set already"); | |
1677 // Skip this foreground collection, instead | |
1678 // expanding the heap if necessary. | |
1679 // Need the free list locks for the call to free() in compute_new_size() | |
1680 compute_new_size(); | |
1681 return; | |
1682 } | |
1683 acquire_control_and_collect(full, clear_all_soft_refs); | |
1684 _full_gcs_since_conc_gc++; | |
1685 } | |
1686 | |
10405 | 1687 void CMSCollector::request_full_gc(unsigned int full_gc_count, GCCause::Cause cause) { |
0 | 1688 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
1689 unsigned int gc_count = gch->total_full_collections(); | |
1690 if (gc_count == full_gc_count) { | |
1691 MutexLockerEx y(CGC_lock, Mutex::_no_safepoint_check_flag); | |
1692 _full_gc_requested = true; | |
10405 | 1693 _full_gc_cause = cause; |
0 | 1694 CGC_lock->notify(); // nudge CMS thread |
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1695 } else { |
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1696 assert(gc_count > full_gc_count, "Error: causal loop"); |
0 | 1697 } |
1698 } | |
1699 | |
10405 | 1700 bool CMSCollector::is_external_interruption() { |
1701 GCCause::Cause cause = GenCollectedHeap::heap()->gc_cause(); | |
1702 return GCCause::is_user_requested_gc(cause) || | |
1703 GCCause::is_serviceability_requested_gc(cause); | |
1704 } | |
1705 | |
1706 void CMSCollector::report_concurrent_mode_interruption() { | |
1707 if (is_external_interruption()) { | |
1708 if (PrintGCDetails) { | |
1709 gclog_or_tty->print(" (concurrent mode interrupted)"); | |
1710 } | |
1711 } else { | |
1712 if (PrintGCDetails) { | |
1713 gclog_or_tty->print(" (concurrent mode failure)"); | |
1714 } | |
1715 _gc_tracer_cm->report_concurrent_mode_failure(); | |
1716 } | |
1717 } | |
1718 | |
0 | 1719 |
1720 // The foreground and background collectors need to coordinate in order | |
1721 // to make sure that they do not mutually interfere with CMS collections. | |
1722 // When a background collection is active, | |
1723 // the foreground collector may need to take over (preempt) and | |
1724 // synchronously complete an ongoing collection. Depending on the | |
1725 // frequency of the background collections and the heap usage | |
1726 // of the application, this preemption can be seldom or frequent. | |
1727 // There are only certain | |
1728 // points in the background collection that the "collection-baton" | |
1729 // can be passed to the foreground collector. | |
1730 // | |
1731 // The foreground collector will wait for the baton before | |
1732 // starting any part of the collection. The foreground collector | |
1733 // will only wait at one location. | |
1734 // | |
1735 // The background collector will yield the baton before starting a new | |
1736 // phase of the collection (e.g., before initial marking, marking from roots, | |
1737 // precleaning, final re-mark, sweep etc.) This is normally done at the head | |
1738 // of the loop which switches the phases. The background collector does some | |
1739 // of the phases (initial mark, final re-mark) with the world stopped. | |
1740 // Because of locking involved in stopping the world, | |
1741 // the foreground collector should not block waiting for the background | |
1742 // collector when it is doing a stop-the-world phase. The background | |
1743 // collector will yield the baton at an additional point just before | |
1744 // it enters a stop-the-world phase. Once the world is stopped, the | |
1745 // background collector checks the phase of the collection. If the | |
1746 // phase has not changed, it proceeds with the collection. If the | |
1747 // phase has changed, it skips that phase of the collection. See | |
1748 // the comments on the use of the Heap_lock in collect_in_background(). | |
1749 // | |
1750 // Variable used in baton passing. | |
1751 // _foregroundGCIsActive - Set to true by the foreground collector when | |
1752 // it wants the baton. The foreground clears it when it has finished | |
1753 // the collection. | |
1754 // _foregroundGCShouldWait - Set to true by the background collector | |
1755 // when it is running. The foreground collector waits while | |
1756 // _foregroundGCShouldWait is true. | |
1757 // CGC_lock - monitor used to protect access to the above variables | |
1758 // and to notify the foreground and background collectors. | |
1759 // _collectorState - current state of the CMS collection. | |
1760 // | |
1761 // The foreground collector | |
1762 // acquires the CGC_lock | |
1763 // sets _foregroundGCIsActive | |
1764 // waits on the CGC_lock for _foregroundGCShouldWait to be false | |
1765 // various locks acquired in preparation for the collection | |
1766 // are released so as not to block the background collector | |
1767 // that is in the midst of a collection | |
1768 // proceeds with the collection | |
1769 // clears _foregroundGCIsActive | |
1770 // returns | |
1771 // | |
1772 // The background collector in a loop iterating on the phases of the | |
1773 // collection | |
1774 // acquires the CGC_lock | |
1775 // sets _foregroundGCShouldWait | |
1776 // if _foregroundGCIsActive is set | |
1777 // clears _foregroundGCShouldWait, notifies _CGC_lock | |
1778 // waits on _CGC_lock for _foregroundGCIsActive to become false | |
1779 // and exits the loop. | |
1780 // otherwise | |
1781 // proceed with that phase of the collection | |
1782 // if the phase is a stop-the-world phase, | |
1783 // yield the baton once more just before enqueueing | |
1784 // the stop-world CMS operation (executed by the VM thread). | |
1785 // returns after all phases of the collection are done | |
1786 // | |
1787 | |
1788 void CMSCollector::acquire_control_and_collect(bool full, | |
1789 bool clear_all_soft_refs) { | |
1790 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); | |
1791 assert(!Thread::current()->is_ConcurrentGC_thread(), | |
1792 "shouldn't try to acquire control from self!"); | |
1793 | |
1794 // Start the protocol for acquiring control of the | |
1795 // collection from the background collector (aka CMS thread). | |
1796 assert(ConcurrentMarkSweepThread::vm_thread_has_cms_token(), | |
1797 "VM thread should have CMS token"); | |
1798 // Remember the possibly interrupted state of an ongoing | |
1799 // concurrent collection | |
1800 CollectorState first_state = _collectorState; | |
1801 | |
1802 // Signal to a possibly ongoing concurrent collection that | |
1803 // we want to do a foreground collection. | |
1804 _foregroundGCIsActive = true; | |
1805 | |
1806 // Disable incremental mode during a foreground collection. | |
1807 ICMSDisabler icms_disabler; | |
1808 | |
1809 // release locks and wait for a notify from the background collector | |
1810 // releasing the locks in only necessary for phases which | |
1811 // do yields to improve the granularity of the collection. | |
1812 assert_lock_strong(bitMapLock()); | |
1813 // We need to lock the Free list lock for the space that we are | |
1814 // currently collecting. | |
1815 assert(haveFreelistLocks(), "Must be holding free list locks"); | |
1816 bitMapLock()->unlock(); | |
1817 releaseFreelistLocks(); | |
1818 { | |
1819 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
1820 if (_foregroundGCShouldWait) { | |
1821 // We are going to be waiting for action for the CMS thread; | |
1822 // it had better not be gone (for instance at shutdown)! | |
1823 assert(ConcurrentMarkSweepThread::cmst() != NULL, | |
1824 "CMS thread must be running"); | |
1825 // Wait here until the background collector gives us the go-ahead | |
1826 ConcurrentMarkSweepThread::clear_CMS_flag( | |
1827 ConcurrentMarkSweepThread::CMS_vm_has_token); // release token | |
1828 // Get a possibly blocked CMS thread going: | |
1829 // Note that we set _foregroundGCIsActive true above, | |
1830 // without protection of the CGC_lock. | |
1831 CGC_lock->notify(); | |
1832 assert(!ConcurrentMarkSweepThread::vm_thread_wants_cms_token(), | |
1833 "Possible deadlock"); | |
1834 while (_foregroundGCShouldWait) { | |
1835 // wait for notification | |
1836 CGC_lock->wait(Mutex::_no_safepoint_check_flag); | |
1837 // Possibility of delay/starvation here, since CMS token does | |
1838 // not know to give priority to VM thread? Actually, i think | |
1839 // there wouldn't be any delay/starvation, but the proof of | |
1840 // that "fact" (?) appears non-trivial. XXX 20011219YSR | |
1841 } | |
1842 ConcurrentMarkSweepThread::set_CMS_flag( | |
1843 ConcurrentMarkSweepThread::CMS_vm_has_token); | |
1844 } | |
1845 } | |
1846 // The CMS_token is already held. Get back the other locks. | |
1847 assert(ConcurrentMarkSweepThread::vm_thread_has_cms_token(), | |
1848 "VM thread should have CMS token"); | |
1849 getFreelistLocks(); | |
1850 bitMapLock()->lock_without_safepoint_check(); | |
1851 if (TraceCMSState) { | |
1852 gclog_or_tty->print_cr("CMS foreground collector has asked for control " | |
1853 INTPTR_FORMAT " with first state %d", Thread::current(), first_state); | |
1854 gclog_or_tty->print_cr(" gets control with state %d", _collectorState); | |
1855 } | |
1856 | |
1857 // Check if we need to do a compaction, or if not, whether | |
1858 // we need to start the mark-sweep from scratch. | |
1859 bool should_compact = false; | |
1860 bool should_start_over = false; | |
1861 decide_foreground_collection_type(clear_all_soft_refs, | |
1862 &should_compact, &should_start_over); | |
1863 | |
1864 NOT_PRODUCT( | |
1865 if (RotateCMSCollectionTypes) { | |
1866 if (_cmsGen->debug_collection_type() == | |
1867 ConcurrentMarkSweepGeneration::MSC_foreground_collection_type) { | |
1868 should_compact = true; | |
1869 } else if (_cmsGen->debug_collection_type() == | |
1870 ConcurrentMarkSweepGeneration::MS_foreground_collection_type) { | |
1871 should_compact = false; | |
1872 } | |
1873 } | |
1874 ) | |
1875 | |
10405 | 1876 if (first_state > Idling) { |
1877 report_concurrent_mode_interruption(); | |
0 | 1878 } |
1879 | |
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1880 set_did_compact(should_compact); |
0 | 1881 if (should_compact) { |
1882 // If the collection is being acquired from the background | |
1883 // collector, there may be references on the discovered | |
1884 // references lists that have NULL referents (being those | |
1885 // that were concurrently cleared by a mutator) or | |
1886 // that are no longer active (having been enqueued concurrently | |
1887 // by the mutator). | |
1888 // Scrub the list of those references because Mark-Sweep-Compact | |
1889 // code assumes referents are not NULL and that all discovered | |
1890 // Reference objects are active. | |
1891 ref_processor()->clean_up_discovered_references(); | |
1892 | |
10405 | 1893 if (first_state > Idling) { |
1894 save_heap_summary(); | |
1895 } | |
1896 | |
0 | 1897 do_compaction_work(clear_all_soft_refs); |
1898 | |
1899 // Has the GC time limit been exceeded? | |
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1900 DefNewGeneration* young_gen = _young_gen->as_DefNewGeneration(); |
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1901 size_t max_eden_size = young_gen->max_capacity() - |
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1902 young_gen->to()->capacity() - |
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1903 young_gen->from()->capacity(); |
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1904 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
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1905 GCCause::Cause gc_cause = gch->gc_cause(); |
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1906 size_policy()->check_gc_overhead_limit(_young_gen->used(), |
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1907 young_gen->eden()->used(), |
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1908 _cmsGen->max_capacity(), |
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1909 max_eden_size, |
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1910 full, |
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1911 gc_cause, |
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1912 gch->collector_policy()); |
0 | 1913 } else { |
1914 do_mark_sweep_work(clear_all_soft_refs, first_state, | |
1915 should_start_over); | |
1916 } | |
1917 // Reset the expansion cause, now that we just completed | |
1918 // a collection cycle. | |
1919 clear_expansion_cause(); | |
1920 _foregroundGCIsActive = false; | |
1921 return; | |
1922 } | |
1923 | |
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1924 // Resize the tenured generation |
0 | 1925 // after obtaining the free list locks for the |
1926 // two generations. | |
1927 void CMSCollector::compute_new_size() { | |
1928 assert_locked_or_safepoint(Heap_lock); | |
1929 FreelistLocker z(this); | |
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1930 MetaspaceGC::compute_new_size(); |
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1931 _cmsGen->compute_new_size_free_list(); |
0 | 1932 } |
1933 | |
1934 // A work method used by foreground collection to determine | |
1935 // what type of collection (compacting or not, continuing or fresh) | |
1936 // it should do. | |
1937 // NOTE: the intent is to make UseCMSCompactAtFullCollection | |
1938 // and CMSCompactWhenClearAllSoftRefs the default in the future | |
1939 // and do away with the flags after a suitable period. | |
1940 void CMSCollector::decide_foreground_collection_type( | |
1941 bool clear_all_soft_refs, bool* should_compact, | |
1942 bool* should_start_over) { | |
1943 // Normally, we'll compact only if the UseCMSCompactAtFullCollection | |
1944 // flag is set, and we have either requested a System.gc() or | |
1945 // the number of full gc's since the last concurrent cycle | |
1946 // has exceeded the threshold set by CMSFullGCsBeforeCompaction, | |
1947 // or if an incremental collection has failed | |
1948 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
1949 assert(gch->collector_policy()->is_two_generation_policy(), | |
1950 "You may want to check the correctness of the following"); | |
1951 // Inform cms gen if this was due to partial collection failing. | |
1952 // The CMS gen may use this fact to determine its expansion policy. | |
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1953 if (gch->incremental_collection_will_fail(false /* don't consult_young */)) { |
0 | 1954 assert(!_cmsGen->incremental_collection_failed(), |
1955 "Should have been noticed, reacted to and cleared"); | |
1956 _cmsGen->set_incremental_collection_failed(); | |
1957 } | |
1958 *should_compact = | |
1959 UseCMSCompactAtFullCollection && | |
1960 ((_full_gcs_since_conc_gc >= CMSFullGCsBeforeCompaction) || | |
1961 GCCause::is_user_requested_gc(gch->gc_cause()) || | |
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1962 gch->incremental_collection_will_fail(true /* consult_young */)); |
0 | 1963 *should_start_over = false; |
1964 if (clear_all_soft_refs && !*should_compact) { | |
1965 // We are about to do a last ditch collection attempt | |
1966 // so it would normally make sense to do a compaction | |
1967 // to reclaim as much space as possible. | |
1968 if (CMSCompactWhenClearAllSoftRefs) { | |
1969 // Default: The rationale is that in this case either | |
1970 // we are past the final marking phase, in which case | |
1971 // we'd have to start over, or so little has been done | |
1972 // that there's little point in saving that work. Compaction | |
1973 // appears to be the sensible choice in either case. | |
1974 *should_compact = true; | |
1975 } else { | |
1976 // We have been asked to clear all soft refs, but not to | |
1977 // compact. Make sure that we aren't past the final checkpoint | |
1978 // phase, for that is where we process soft refs. If we are already | |
1979 // past that phase, we'll need to redo the refs discovery phase and | |
1980 // if necessary clear soft refs that weren't previously | |
1981 // cleared. We do so by remembering the phase in which | |
1982 // we came in, and if we are past the refs processing | |
1983 // phase, we'll choose to just redo the mark-sweep | |
1984 // collection from scratch. | |
1985 if (_collectorState > FinalMarking) { | |
1986 // We are past the refs processing phase; | |
1987 // start over and do a fresh synchronous CMS cycle | |
1988 _collectorState = Resetting; // skip to reset to start new cycle | |
1989 reset(false /* == !asynch */); | |
1990 *should_start_over = true; | |
1991 } // else we can continue a possibly ongoing current cycle | |
1992 } | |
1993 } | |
1994 } | |
1995 | |
1996 // A work method used by the foreground collector to do | |
1997 // a mark-sweep-compact. | |
1998 void CMSCollector::do_compaction_work(bool clear_all_soft_refs) { | |
1999 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
10405 | 2000 |
2001 STWGCTimer* gc_timer = GenMarkSweep::gc_timer(); | |
2002 gc_timer->register_gc_start(os::elapsed_counter()); | |
2003 | |
2004 SerialOldTracer* gc_tracer = GenMarkSweep::gc_tracer(); | |
2005 gc_tracer->report_gc_start(gch->gc_cause(), gc_timer->gc_start()); | |
2006 | |
2007 GCTraceTime t("CMS:MSC ", PrintGCDetails && Verbose, true, NULL); | |
0 | 2008 if (PrintGC && Verbose && !(GCCause::is_user_requested_gc(gch->gc_cause()))) { |
2009 gclog_or_tty->print_cr("Compact ConcurrentMarkSweepGeneration after %d " | |
2010 "collections passed to foreground collector", _full_gcs_since_conc_gc); | |
2011 } | |
2012 | |
2013 // Sample collection interval time and reset for collection pause. | |
2014 if (UseAdaptiveSizePolicy) { | |
2015 size_policy()->msc_collection_begin(); | |
2016 } | |
2017 | |
2018 // Temporarily widen the span of the weak reference processing to | |
2019 // the entire heap. | |
2020 MemRegion new_span(GenCollectedHeap::heap()->reserved_region()); | |
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2021 ReferenceProcessorSpanMutator rp_mut_span(ref_processor(), new_span); |
0 | 2022 // Temporarily, clear the "is_alive_non_header" field of the |
2023 // reference processor. | |
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2024 ReferenceProcessorIsAliveMutator rp_mut_closure(ref_processor(), NULL); |
0 | 2025 // Temporarily make reference _processing_ single threaded (non-MT). |
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2026 ReferenceProcessorMTProcMutator rp_mut_mt_processing(ref_processor(), false); |
0 | 2027 // Temporarily make refs discovery atomic |
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2028 ReferenceProcessorAtomicMutator rp_mut_atomic(ref_processor(), true); |
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2029 // Temporarily make reference _discovery_ single threaded (non-MT) |
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2030 ReferenceProcessorMTDiscoveryMutator rp_mut_discovery(ref_processor(), false); |
0 | 2031 |
2032 ref_processor()->set_enqueuing_is_done(false); | |
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2033 ref_processor()->enable_discovery(false /*verify_disabled*/, false /*check_no_refs*/); |
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2034 ref_processor()->setup_policy(clear_all_soft_refs); |
0 | 2035 // If an asynchronous collection finishes, the _modUnionTable is |
2036 // all clear. If we are assuming the collection from an asynchronous | |
2037 // collection, clear the _modUnionTable. | |
2038 assert(_collectorState != Idling || _modUnionTable.isAllClear(), | |
2039 "_modUnionTable should be clear if the baton was not passed"); | |
2040 _modUnionTable.clear_all(); | |
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2041 assert(_collectorState != Idling || _ct->klass_rem_set()->mod_union_is_clear(), |
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2042 "mod union for klasses should be clear if the baton was passed"); |
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2043 _ct->klass_rem_set()->clear_mod_union(); |
0 | 2044 |
2045 // We must adjust the allocation statistics being maintained | |
2046 // in the free list space. We do so by reading and clearing | |
2047 // the sweep timer and updating the block flux rate estimates below. | |
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2048 assert(!_intra_sweep_timer.is_active(), "_intra_sweep_timer should be inactive"); |
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2049 if (_inter_sweep_timer.is_active()) { |
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2050 _inter_sweep_timer.stop(); |
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2051 // Note that we do not use this sample to update the _inter_sweep_estimate. |
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2052 _cmsGen->cmsSpace()->beginSweepFLCensus((float)(_inter_sweep_timer.seconds()), |
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2053 _inter_sweep_estimate.padded_average(), |
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2054 _intra_sweep_estimate.padded_average()); |
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2055 } |
0 | 2056 |
2057 GenMarkSweep::invoke_at_safepoint(_cmsGen->level(), | |
2058 ref_processor(), clear_all_soft_refs); | |
2059 #ifdef ASSERT | |
2060 CompactibleFreeListSpace* cms_space = _cmsGen->cmsSpace(); | |
2061 size_t free_size = cms_space->free(); | |
2062 assert(free_size == | |
2063 pointer_delta(cms_space->end(), cms_space->compaction_top()) | |
2064 * HeapWordSize, | |
2065 "All the free space should be compacted into one chunk at top"); | |
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2066 assert(cms_space->dictionary()->total_chunk_size( |
0 | 2067 debug_only(cms_space->freelistLock())) == 0 || |
2068 cms_space->totalSizeInIndexedFreeLists() == 0, | |
2069 "All the free space should be in a single chunk"); | |
2070 size_t num = cms_space->totalCount(); | |
2071 assert((free_size == 0 && num == 0) || | |
2072 (free_size > 0 && (num == 1 || num == 2)), | |
2073 "There should be at most 2 free chunks after compaction"); | |
2074 #endif // ASSERT | |
2075 _collectorState = Resetting; | |
2076 assert(_restart_addr == NULL, | |
2077 "Should have been NULL'd before baton was passed"); | |
2078 reset(false /* == !asynch */); | |
2079 _cmsGen->reset_after_compaction(); | |
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2080 _concurrent_cycles_since_last_unload = 0; |
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2081 |
0 | 2082 // Clear any data recorded in the PLAB chunk arrays. |
2083 if (_survivor_plab_array != NULL) { | |
2084 reset_survivor_plab_arrays(); | |
2085 } | |
2086 | |
2087 // Adjust the per-size allocation stats for the next epoch. | |
1145
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2088 _cmsGen->cmsSpace()->endSweepFLCensus(sweep_count() /* fake */); |
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2089 // Restart the "inter sweep timer" for the next epoch. |
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2090 _inter_sweep_timer.reset(); |
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2091 _inter_sweep_timer.start(); |
0 | 2092 |
2093 // Sample collection pause time and reset for collection interval. | |
2094 if (UseAdaptiveSizePolicy) { | |
2095 size_policy()->msc_collection_end(gch->gc_cause()); | |
2096 } | |
2097 | |
10405 | 2098 gc_timer->register_gc_end(os::elapsed_counter()); |
2099 | |
2100 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); | |
2101 | |
0 | 2102 // For a mark-sweep-compact, compute_new_size() will be called |
2103 // in the heap's do_collection() method. | |
2104 } | |
2105 | |
2106 // A work method used by the foreground collector to do | |
2107 // a mark-sweep, after taking over from a possibly on-going | |
2108 // concurrent mark-sweep collection. | |
2109 void CMSCollector::do_mark_sweep_work(bool clear_all_soft_refs, | |
2110 CollectorState first_state, bool should_start_over) { | |
2111 if (PrintGC && Verbose) { | |
2112 gclog_or_tty->print_cr("Pass concurrent collection to foreground " | |
2113 "collector with count %d", | |
2114 _full_gcs_since_conc_gc); | |
2115 } | |
2116 switch (_collectorState) { | |
2117 case Idling: | |
2118 if (first_state == Idling || should_start_over) { | |
2119 // The background GC was not active, or should | |
2120 // restarted from scratch; start the cycle. | |
2121 _collectorState = InitialMarking; | |
2122 } | |
2123 // If first_state was not Idling, then a background GC | |
2124 // was in progress and has now finished. No need to do it | |
2125 // again. Leave the state as Idling. | |
2126 break; | |
2127 case Precleaning: | |
2128 // In the foreground case don't do the precleaning since | |
2129 // it is not done concurrently and there is extra work | |
2130 // required. | |
2131 _collectorState = FinalMarking; | |
2132 } | |
10405 | 2133 collect_in_foreground(clear_all_soft_refs, GenCollectedHeap::heap()->gc_cause()); |
0 | 2134 |
2135 // For a mark-sweep, compute_new_size() will be called | |
2136 // in the heap's do_collection() method. | |
2137 } | |
2138 | |
2139 | |
2140 void CMSCollector::getFreelistLocks() const { | |
2141 // Get locks for all free lists in all generations that this | |
2142 // collector is responsible for | |
2143 _cmsGen->freelistLock()->lock_without_safepoint_check(); | |
2144 } | |
2145 | |
2146 void CMSCollector::releaseFreelistLocks() const { | |
2147 // Release locks for all free lists in all generations that this | |
2148 // collector is responsible for | |
2149 _cmsGen->freelistLock()->unlock(); | |
2150 } | |
2151 | |
2152 bool CMSCollector::haveFreelistLocks() const { | |
2153 // Check locks for all free lists in all generations that this | |
2154 // collector is responsible for | |
2155 assert_lock_strong(_cmsGen->freelistLock()); | |
2156 PRODUCT_ONLY(ShouldNotReachHere()); | |
2157 return true; | |
2158 } | |
2159 | |
2160 // A utility class that is used by the CMS collector to | |
2161 // temporarily "release" the foreground collector from its | |
2162 // usual obligation to wait for the background collector to | |
2163 // complete an ongoing phase before proceeding. | |
2164 class ReleaseForegroundGC: public StackObj { | |
2165 private: | |
2166 CMSCollector* _c; | |
2167 public: | |
2168 ReleaseForegroundGC(CMSCollector* c) : _c(c) { | |
2169 assert(_c->_foregroundGCShouldWait, "Else should not need to call"); | |
2170 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
2171 // allow a potentially blocked foreground collector to proceed | |
2172 _c->_foregroundGCShouldWait = false; | |
2173 if (_c->_foregroundGCIsActive) { | |
2174 CGC_lock->notify(); | |
2175 } | |
2176 assert(!ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
2177 "Possible deadlock"); | |
2178 } | |
2179 | |
2180 ~ReleaseForegroundGC() { | |
2181 assert(!_c->_foregroundGCShouldWait, "Usage protocol violation?"); | |
2182 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
2183 _c->_foregroundGCShouldWait = true; | |
2184 } | |
2185 }; | |
2186 | |
2187 // There are separate collect_in_background and collect_in_foreground because of | |
2188 // the different locking requirements of the background collector and the | |
2189 // foreground collector. There was originally an attempt to share | |
2190 // one "collect" method between the background collector and the foreground | |
2191 // collector but the if-then-else required made it cleaner to have | |
2192 // separate methods. | |
10405 | 2193 void CMSCollector::collect_in_background(bool clear_all_soft_refs, GCCause::Cause cause) { |
0 | 2194 assert(Thread::current()->is_ConcurrentGC_thread(), |
2195 "A CMS asynchronous collection is only allowed on a CMS thread."); | |
2196 | |
2197 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
2198 { | |
2199 bool safepoint_check = Mutex::_no_safepoint_check_flag; | |
2200 MutexLockerEx hl(Heap_lock, safepoint_check); | |
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2201 FreelistLocker fll(this); |
0 | 2202 MutexLockerEx x(CGC_lock, safepoint_check); |
2203 if (_foregroundGCIsActive || !UseAsyncConcMarkSweepGC) { | |
2204 // The foreground collector is active or we're | |
2205 // not using asynchronous collections. Skip this | |
2206 // background collection. | |
2207 assert(!_foregroundGCShouldWait, "Should be clear"); | |
2208 return; | |
2209 } else { | |
2210 assert(_collectorState == Idling, "Should be idling before start."); | |
2211 _collectorState = InitialMarking; | |
10405 | 2212 register_gc_start(cause); |
0 | 2213 // Reset the expansion cause, now that we are about to begin |
2214 // a new cycle. | |
2215 clear_expansion_cause(); | |
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2216 |
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2217 // Clear the MetaspaceGC flag since a concurrent collection |
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2218 // is starting but also clear it after the collection. |
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2219 MetaspaceGC::set_should_concurrent_collect(false); |
0 | 2220 } |
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2221 // Decide if we want to enable class unloading as part of the |
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2222 // ensuing concurrent GC cycle. |
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2223 update_should_unload_classes(); |
0 | 2224 _full_gc_requested = false; // acks all outstanding full gc requests |
10405 | 2225 _full_gc_cause = GCCause::_no_gc; |
0 | 2226 // Signal that we are about to start a collection |
2227 gch->increment_total_full_collections(); // ... starting a collection cycle | |
2228 _collection_count_start = gch->total_full_collections(); | |
2229 } | |
2230 | |
2231 // Used for PrintGC | |
2232 size_t prev_used; | |
2233 if (PrintGC && Verbose) { | |
2234 prev_used = _cmsGen->used(); // XXXPERM | |
2235 } | |
2236 | |
2237 // The change of the collection state is normally done at this level; | |
2238 // the exceptions are phases that are executed while the world is | |
2239 // stopped. For those phases the change of state is done while the | |
2240 // world is stopped. For baton passing purposes this allows the | |
2241 // background collector to finish the phase and change state atomically. | |
2242 // The foreground collector cannot wait on a phase that is done | |
2243 // while the world is stopped because the foreground collector already | |
2244 // has the world stopped and would deadlock. | |
2245 while (_collectorState != Idling) { | |
2246 if (TraceCMSState) { | |
2247 gclog_or_tty->print_cr("Thread " INTPTR_FORMAT " in CMS state %d", | |
2248 Thread::current(), _collectorState); | |
2249 } | |
2250 // The foreground collector | |
2251 // holds the Heap_lock throughout its collection. | |
2252 // holds the CMS token (but not the lock) | |
2253 // except while it is waiting for the background collector to yield. | |
2254 // | |
2255 // The foreground collector should be blocked (not for long) | |
2256 // if the background collector is about to start a phase | |
2257 // executed with world stopped. If the background | |
2258 // collector has already started such a phase, the | |
2259 // foreground collector is blocked waiting for the | |
2260 // Heap_lock. The stop-world phases (InitialMarking and FinalMarking) | |
2261 // are executed in the VM thread. | |
2262 // | |
2263 // The locking order is | |
2264 // PendingListLock (PLL) -- if applicable (FinalMarking) | |
2265 // Heap_lock (both this & PLL locked in VM_CMS_Operation::prologue()) | |
2266 // CMS token (claimed in | |
2267 // stop_world_and_do() --> | |
2268 // safepoint_synchronize() --> | |
2269 // CMSThread::synchronize()) | |
2270 | |
2271 { | |
2272 // Check if the FG collector wants us to yield. | |
2273 CMSTokenSync x(true); // is cms thread | |
2274 if (waitForForegroundGC()) { | |
2275 // We yielded to a foreground GC, nothing more to be | |
2276 // done this round. | |
2277 assert(_foregroundGCShouldWait == false, "We set it to false in " | |
2278 "waitForForegroundGC()"); | |
2279 if (TraceCMSState) { | |
2280 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT | |
2281 " exiting collection CMS state %d", | |
2282 Thread::current(), _collectorState); | |
2283 } | |
2284 return; | |
2285 } else { | |
2286 // The background collector can run but check to see if the | |
2287 // foreground collector has done a collection while the | |
2288 // background collector was waiting to get the CGC_lock | |
2289 // above. If yes, break so that _foregroundGCShouldWait | |
2290 // is cleared before returning. | |
2291 if (_collectorState == Idling) { | |
2292 break; | |
2293 } | |
2294 } | |
2295 } | |
2296 | |
2297 assert(_foregroundGCShouldWait, "Foreground collector, if active, " | |
2298 "should be waiting"); | |
2299 | |
2300 switch (_collectorState) { | |
2301 case InitialMarking: | |
2302 { | |
2303 ReleaseForegroundGC x(this); | |
2304 stats().record_cms_begin(); | |
2305 VM_CMS_Initial_Mark initial_mark_op(this); | |
2306 VMThread::execute(&initial_mark_op); | |
2307 } | |
2308 // The collector state may be any legal state at this point | |
2309 // since the background collector may have yielded to the | |
2310 // foreground collector. | |
2311 break; | |
2312 case Marking: | |
2313 // initial marking in checkpointRootsInitialWork has been completed | |
2314 if (markFromRoots(true)) { // we were successful | |
2315 assert(_collectorState == Precleaning, "Collector state should " | |
2316 "have changed"); | |
2317 } else { | |
2318 assert(_foregroundGCIsActive, "Internal state inconsistency"); | |
2319 } | |
2320 break; | |
2321 case Precleaning: | |
2322 if (UseAdaptiveSizePolicy) { | |
2323 size_policy()->concurrent_precleaning_begin(); | |
2324 } | |
2325 // marking from roots in markFromRoots has been completed | |
2326 preclean(); | |
2327 if (UseAdaptiveSizePolicy) { | |
2328 size_policy()->concurrent_precleaning_end(); | |
2329 } | |
2330 assert(_collectorState == AbortablePreclean || | |
2331 _collectorState == FinalMarking, | |
2332 "Collector state should have changed"); | |
2333 break; | |
2334 case AbortablePreclean: | |
2335 if (UseAdaptiveSizePolicy) { | |
2336 size_policy()->concurrent_phases_resume(); | |
2337 } | |
2338 abortable_preclean(); | |
2339 if (UseAdaptiveSizePolicy) { | |
2340 size_policy()->concurrent_precleaning_end(); | |
2341 } | |
2342 assert(_collectorState == FinalMarking, "Collector state should " | |
2343 "have changed"); | |
2344 break; | |
2345 case FinalMarking: | |
2346 { | |
2347 ReleaseForegroundGC x(this); | |
2348 | |
2349 VM_CMS_Final_Remark final_remark_op(this); | |
2350 VMThread::execute(&final_remark_op); | |
935 | 2351 } |
0 | 2352 assert(_foregroundGCShouldWait, "block post-condition"); |
2353 break; | |
2354 case Sweeping: | |
2355 if (UseAdaptiveSizePolicy) { | |
2356 size_policy()->concurrent_sweeping_begin(); | |
2357 } | |
2358 // final marking in checkpointRootsFinal has been completed | |
2359 sweep(true); | |
2360 assert(_collectorState == Resizing, "Collector state change " | |
2361 "to Resizing must be done under the free_list_lock"); | |
2362 _full_gcs_since_conc_gc = 0; | |
2363 | |
2364 // Stop the timers for adaptive size policy for the concurrent phases | |
2365 if (UseAdaptiveSizePolicy) { | |
2366 size_policy()->concurrent_sweeping_end(); | |
2367 size_policy()->concurrent_phases_end(gch->gc_cause(), | |
2368 gch->prev_gen(_cmsGen)->capacity(), | |
2369 _cmsGen->free()); | |
2370 } | |
2371 | |
2372 case Resizing: { | |
2373 // Sweeping has been completed... | |
2374 // At this point the background collection has completed. | |
2375 // Don't move the call to compute_new_size() down | |
2376 // into code that might be executed if the background | |
2377 // collection was preempted. | |
2378 { | |
2379 ReleaseForegroundGC x(this); // unblock FG collection | |
2380 MutexLockerEx y(Heap_lock, Mutex::_no_safepoint_check_flag); | |
2381 CMSTokenSync z(true); // not strictly needed. | |
2382 if (_collectorState == Resizing) { | |
2383 compute_new_size(); | |
10405 | 2384 save_heap_summary(); |
0 | 2385 _collectorState = Resetting; |
2386 } else { | |
2387 assert(_collectorState == Idling, "The state should only change" | |
2388 " because the foreground collector has finished the collection"); | |
2389 } | |
2390 } | |
2391 break; | |
2392 } | |
2393 case Resetting: | |
2394 // CMS heap resizing has been completed | |
2395 reset(true); | |
2396 assert(_collectorState == Idling, "Collector state should " | |
2397 "have changed"); | |
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2398 |
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2399 MetaspaceGC::set_should_concurrent_collect(false); |
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2400 |
0 | 2401 stats().record_cms_end(); |
2402 // Don't move the concurrent_phases_end() and compute_new_size() | |
2403 // calls to here because a preempted background collection | |
2404 // has it's state set to "Resetting". | |
2405 break; | |
2406 case Idling: | |
2407 default: | |
2408 ShouldNotReachHere(); | |
2409 break; | |
2410 } | |
2411 if (TraceCMSState) { | |
2412 gclog_or_tty->print_cr(" Thread " INTPTR_FORMAT " done - next CMS state %d", | |
2413 Thread::current(), _collectorState); | |
2414 } | |
2415 assert(_foregroundGCShouldWait, "block post-condition"); | |
2416 } | |
2417 | |
2418 // Should this be in gc_epilogue? | |
2419 collector_policy()->counters()->update_counters(); | |
2420 | |
2421 { | |
2422 // Clear _foregroundGCShouldWait and, in the event that the | |
2423 // foreground collector is waiting, notify it, before | |
2424 // returning. | |
2425 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
2426 _foregroundGCShouldWait = false; | |
2427 if (_foregroundGCIsActive) { | |
2428 CGC_lock->notify(); | |
2429 } | |
2430 assert(!ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
2431 "Possible deadlock"); | |
2432 } | |
2433 if (TraceCMSState) { | |
2434 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT | |
2435 " exiting collection CMS state %d", | |
2436 Thread::current(), _collectorState); | |
2437 } | |
2438 if (PrintGC && Verbose) { | |
2439 _cmsGen->print_heap_change(prev_used); | |
2440 } | |
2441 } | |
2442 | |
10405 | 2443 void CMSCollector::register_foreground_gc_start(GCCause::Cause cause) { |
2444 if (!_cms_start_registered) { | |
2445 register_gc_start(cause); | |
2446 } | |
2447 } | |
2448 | |
2449 void CMSCollector::register_gc_start(GCCause::Cause cause) { | |
2450 _cms_start_registered = true; | |
2451 _gc_timer_cm->register_gc_start(os::elapsed_counter()); | |
2452 _gc_tracer_cm->report_gc_start(cause, _gc_timer_cm->gc_start()); | |
2453 } | |
2454 | |
2455 void CMSCollector::register_gc_end() { | |
2456 if (_cms_start_registered) { | |
2457 report_heap_summary(GCWhen::AfterGC); | |
2458 | |
2459 _gc_timer_cm->register_gc_end(os::elapsed_counter()); | |
2460 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); | |
2461 _cms_start_registered = false; | |
2462 } | |
2463 } | |
2464 | |
2465 void CMSCollector::save_heap_summary() { | |
2466 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
2467 _last_heap_summary = gch->create_heap_summary(); | |
2468 _last_metaspace_summary = gch->create_metaspace_summary(); | |
2469 } | |
2470 | |
2471 void CMSCollector::report_heap_summary(GCWhen::Type when) { | |
2472 _gc_tracer_cm->report_gc_heap_summary(when, _last_heap_summary, _last_metaspace_summary); | |
2473 } | |
2474 | |
2475 void CMSCollector::collect_in_foreground(bool clear_all_soft_refs, GCCause::Cause cause) { | |
0 | 2476 assert(_foregroundGCIsActive && !_foregroundGCShouldWait, |
2477 "Foreground collector should be waiting, not executing"); | |
2478 assert(Thread::current()->is_VM_thread(), "A foreground collection" | |
2479 "may only be done by the VM Thread with the world stopped"); | |
2480 assert(ConcurrentMarkSweepThread::vm_thread_has_cms_token(), | |
2481 "VM thread should have CMS token"); | |
2482 | |
10405 | 2483 NOT_PRODUCT(GCTraceTime t("CMS:MS (foreground) ", PrintGCDetails && Verbose, |
2484 true, NULL);) | |
0 | 2485 if (UseAdaptiveSizePolicy) { |
2486 size_policy()->ms_collection_begin(); | |
2487 } | |
2488 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact); | |
2489 | |
2490 HandleMark hm; // Discard invalid handles created during verification | |
2491 | |
2492 if (VerifyBeforeGC && | |
2493 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
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2494 Universe::verify(); |
0 | 2495 } |
2496 | |
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2497 // Snapshot the soft reference policy to be used in this collection cycle. |
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2498 ref_processor()->setup_policy(clear_all_soft_refs); |
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2499 |
0 | 2500 bool init_mark_was_synchronous = false; // until proven otherwise |
2501 while (_collectorState != Idling) { | |
2502 if (TraceCMSState) { | |
2503 gclog_or_tty->print_cr("Thread " INTPTR_FORMAT " in CMS state %d", | |
2504 Thread::current(), _collectorState); | |
2505 } | |
2506 switch (_collectorState) { | |
2507 case InitialMarking: | |
10405 | 2508 register_foreground_gc_start(cause); |
0 | 2509 init_mark_was_synchronous = true; // fact to be exploited in re-mark |
2510 checkpointRootsInitial(false); | |
2511 assert(_collectorState == Marking, "Collector state should have changed" | |
2512 " within checkpointRootsInitial()"); | |
2513 break; | |
2514 case Marking: | |
2515 // initial marking in checkpointRootsInitialWork has been completed | |
2516 if (VerifyDuringGC && | |
2517 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
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2518 Universe::verify("Verify before initial mark: "); |
0 | 2519 } |
2520 { | |
2521 bool res = markFromRoots(false); | |
2522 assert(res && _collectorState == FinalMarking, "Collector state should " | |
2523 "have changed"); | |
2524 break; | |
2525 } | |
2526 case FinalMarking: | |
2527 if (VerifyDuringGC && | |
2528 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
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2529 Universe::verify("Verify before re-mark: "); |
0 | 2530 } |
2531 checkpointRootsFinal(false, clear_all_soft_refs, | |
2532 init_mark_was_synchronous); | |
2533 assert(_collectorState == Sweeping, "Collector state should not " | |
2534 "have changed within checkpointRootsFinal()"); | |
2535 break; | |
2536 case Sweeping: | |
2537 // final marking in checkpointRootsFinal has been completed | |
2538 if (VerifyDuringGC && | |
2539 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
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2540 Universe::verify("Verify before sweep: "); |
0 | 2541 } |
2542 sweep(false); | |
2543 assert(_collectorState == Resizing, "Incorrect state"); | |
2544 break; | |
2545 case Resizing: { | |
2546 // Sweeping has been completed; the actual resize in this case | |
2547 // is done separately; nothing to be done in this state. | |
2548 _collectorState = Resetting; | |
2549 break; | |
2550 } | |
2551 case Resetting: | |
2552 // The heap has been resized. | |
2553 if (VerifyDuringGC && | |
2554 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
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2555 Universe::verify("Verify before reset: "); |
0 | 2556 } |
10405 | 2557 save_heap_summary(); |
0 | 2558 reset(false); |
2559 assert(_collectorState == Idling, "Collector state should " | |
2560 "have changed"); | |
2561 break; | |
2562 case Precleaning: | |
2563 case AbortablePreclean: | |
2564 // Elide the preclean phase | |
2565 _collectorState = FinalMarking; | |
2566 break; | |
2567 default: | |
2568 ShouldNotReachHere(); | |
2569 } | |
2570 if (TraceCMSState) { | |
2571 gclog_or_tty->print_cr(" Thread " INTPTR_FORMAT " done - next CMS state %d", | |
2572 Thread::current(), _collectorState); | |
2573 } | |
2574 } | |
2575 | |
2576 if (UseAdaptiveSizePolicy) { | |
2577 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
2578 size_policy()->ms_collection_end(gch->gc_cause()); | |
2579 } | |
2580 | |
2581 if (VerifyAfterGC && | |
2582 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
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2583 Universe::verify(); |
0 | 2584 } |
2585 if (TraceCMSState) { | |
2586 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT | |
2587 " exiting collection CMS state %d", | |
2588 Thread::current(), _collectorState); | |
2589 } | |
2590 } | |
2591 | |
2592 bool CMSCollector::waitForForegroundGC() { | |
2593 bool res = false; | |
2594 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
2595 "CMS thread should have CMS token"); | |
2596 // Block the foreground collector until the | |
2597 // background collectors decides whether to | |
2598 // yield. | |
2599 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
2600 _foregroundGCShouldWait = true; | |
2601 if (_foregroundGCIsActive) { | |
2602 // The background collector yields to the | |
2603 // foreground collector and returns a value | |
2604 // indicating that it has yielded. The foreground | |
2605 // collector can proceed. | |
2606 res = true; | |
2607 _foregroundGCShouldWait = false; | |
2608 ConcurrentMarkSweepThread::clear_CMS_flag( | |
2609 ConcurrentMarkSweepThread::CMS_cms_has_token); | |
2610 ConcurrentMarkSweepThread::set_CMS_flag( | |
2611 ConcurrentMarkSweepThread::CMS_cms_wants_token); | |
2612 // Get a possibly blocked foreground thread going | |
2613 CGC_lock->notify(); | |
2614 if (TraceCMSState) { | |
2615 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT " waiting at CMS state %d", | |
2616 Thread::current(), _collectorState); | |
2617 } | |
2618 while (_foregroundGCIsActive) { | |
2619 CGC_lock->wait(Mutex::_no_safepoint_check_flag); | |
2620 } | |
2621 ConcurrentMarkSweepThread::set_CMS_flag( | |
2622 ConcurrentMarkSweepThread::CMS_cms_has_token); | |
2623 ConcurrentMarkSweepThread::clear_CMS_flag( | |
2624 ConcurrentMarkSweepThread::CMS_cms_wants_token); | |
2625 } | |
2626 if (TraceCMSState) { | |
2627 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT " continuing at CMS state %d", | |
2628 Thread::current(), _collectorState); | |
2629 } | |
2630 return res; | |
2631 } | |
2632 | |
2633 // Because of the need to lock the free lists and other structures in | |
2634 // the collector, common to all the generations that the collector is | |
2635 // collecting, we need the gc_prologues of individual CMS generations | |
2636 // delegate to their collector. It may have been simpler had the | |
2637 // current infrastructure allowed one to call a prologue on a | |
2638 // collector. In the absence of that we have the generation's | |
2639 // prologue delegate to the collector, which delegates back | |
2640 // some "local" work to a worker method in the individual generations | |
2641 // that it's responsible for collecting, while itself doing any | |
2642 // work common to all generations it's responsible for. A similar | |
2643 // comment applies to the gc_epilogue()'s. | |
2644 // The role of the varaible _between_prologue_and_epilogue is to | |
2645 // enforce the invocation protocol. | |
2646 void CMSCollector::gc_prologue(bool full) { | |
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2647 // Call gc_prologue_work() for the CMSGen |
0 | 2648 // we are responsible for. |
2649 | |
2650 // The following locking discipline assumes that we are only called | |
2651 // when the world is stopped. | |
2652 assert(SafepointSynchronize::is_at_safepoint(), "world is stopped assumption"); | |
2653 | |
2654 // The CMSCollector prologue must call the gc_prologues for the | |
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2655 // "generations" that it's responsible |
0 | 2656 // for. |
2657 | |
2658 assert( Thread::current()->is_VM_thread() | |
2659 || ( CMSScavengeBeforeRemark | |
2660 && Thread::current()->is_ConcurrentGC_thread()), | |
2661 "Incorrect thread type for prologue execution"); | |
2662 | |
2663 if (_between_prologue_and_epilogue) { | |
2664 // We have already been invoked; this is a gc_prologue delegation | |
2665 // from yet another CMS generation that we are responsible for, just | |
2666 // ignore it since all relevant work has already been done. | |
2667 return; | |
2668 } | |
2669 | |
2670 // set a bit saying prologue has been called; cleared in epilogue | |
2671 _between_prologue_and_epilogue = true; | |
2672 // Claim locks for common data structures, then call gc_prologue_work() | |
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2673 // for each CMSGen. |
0 | 2674 |
2675 getFreelistLocks(); // gets free list locks on constituent spaces | |
2676 bitMapLock()->lock_without_safepoint_check(); | |
2677 | |
2678 // Should call gc_prologue_work() for all cms gens we are responsible for | |
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2679 bool duringMarking = _collectorState >= Marking |
0 | 2680 && _collectorState < Sweeping; |
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2681 |
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2682 // The young collections clear the modified oops state, which tells if |
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2683 // there are any modified oops in the class. The remark phase also needs |
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2684 // that information. Tell the young collection to save the union of all |
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2685 // modified klasses. |
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2686 if (duringMarking) { |
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2687 _ct->klass_rem_set()->set_accumulate_modified_oops(true); |
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2688 } |
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2689 |
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2690 bool registerClosure = duringMarking; |
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2691 |
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2692 ModUnionClosure* muc = CollectedHeap::use_parallel_gc_threads() ? |
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2693 &_modUnionClosurePar |
0 | 2694 : &_modUnionClosure; |
2695 _cmsGen->gc_prologue_work(full, registerClosure, muc); | |
2696 | |
2697 if (!full) { | |
2698 stats().record_gc0_begin(); | |
2699 } | |
2700 } | |
2701 | |
2702 void ConcurrentMarkSweepGeneration::gc_prologue(bool full) { | |
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2703 |
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2704 _capacity_at_prologue = capacity(); |
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2705 _used_at_prologue = used(); |
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2706 |
0 | 2707 // Delegate to CMScollector which knows how to coordinate between |
2708 // this and any other CMS generations that it is responsible for | |
2709 // collecting. | |
2710 collector()->gc_prologue(full); | |
2711 } | |
2712 | |
2713 // This is a "private" interface for use by this generation's CMSCollector. | |
2714 // Not to be called directly by any other entity (for instance, | |
2715 // GenCollectedHeap, which calls the "public" gc_prologue method above). | |
2716 void ConcurrentMarkSweepGeneration::gc_prologue_work(bool full, | |
2717 bool registerClosure, ModUnionClosure* modUnionClosure) { | |
2718 assert(!incremental_collection_failed(), "Shouldn't be set yet"); | |
2719 assert(cmsSpace()->preconsumptionDirtyCardClosure() == NULL, | |
2720 "Should be NULL"); | |
2721 if (registerClosure) { | |
2722 cmsSpace()->setPreconsumptionDirtyCardClosure(modUnionClosure); | |
2723 } | |
2724 cmsSpace()->gc_prologue(); | |
2725 // Clear stat counters | |
2726 NOT_PRODUCT( | |
2727 assert(_numObjectsPromoted == 0, "check"); | |
2728 assert(_numWordsPromoted == 0, "check"); | |
2729 if (Verbose && PrintGC) { | |
2730 gclog_or_tty->print("Allocated "SIZE_FORMAT" objects, " | |
2731 SIZE_FORMAT" bytes concurrently", | |
2732 _numObjectsAllocated, _numWordsAllocated*sizeof(HeapWord)); | |
2733 } | |
2734 _numObjectsAllocated = 0; | |
2735 _numWordsAllocated = 0; | |
2736 ) | |
2737 } | |
2738 | |
2739 void CMSCollector::gc_epilogue(bool full) { | |
2740 // The following locking discipline assumes that we are only called | |
2741 // when the world is stopped. | |
2742 assert(SafepointSynchronize::is_at_safepoint(), | |
2743 "world is stopped assumption"); | |
2744 | |
2745 // Currently the CMS epilogue (see CompactibleFreeListSpace) merely checks | |
2746 // if linear allocation blocks need to be appropriately marked to allow the | |
2747 // the blocks to be parsable. We also check here whether we need to nudge the | |
2748 // CMS collector thread to start a new cycle (if it's not already active). | |
2749 assert( Thread::current()->is_VM_thread() | |
2750 || ( CMSScavengeBeforeRemark | |
2751 && Thread::current()->is_ConcurrentGC_thread()), | |
2752 "Incorrect thread type for epilogue execution"); | |
2753 | |
2754 if (!_between_prologue_and_epilogue) { | |
2755 // We have already been invoked; this is a gc_epilogue delegation | |
2756 // from yet another CMS generation that we are responsible for, just | |
2757 // ignore it since all relevant work has already been done. | |
2758 return; | |
2759 } | |
2760 assert(haveFreelistLocks(), "must have freelist locks"); | |
2761 assert_lock_strong(bitMapLock()); | |
2762 | |
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2763 _ct->klass_rem_set()->set_accumulate_modified_oops(false); |
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2764 |
0 | 2765 _cmsGen->gc_epilogue_work(full); |
2766 | |
2767 if (_collectorState == AbortablePreclean || _collectorState == Precleaning) { | |
2768 // in case sampling was not already enabled, enable it | |
2769 _start_sampling = true; | |
2770 } | |
2771 // reset _eden_chunk_array so sampling starts afresh | |
2772 _eden_chunk_index = 0; | |
2773 | |
2774 size_t cms_used = _cmsGen->cmsSpace()->used(); | |
2775 | |
2776 // update performance counters - this uses a special version of | |
2777 // update_counters() that allows the utilization to be passed as a | |
2778 // parameter, avoiding multiple calls to used(). | |
2779 // | |
2780 _cmsGen->update_counters(cms_used); | |
2781 | |
2782 if (CMSIncrementalMode) { | |
2783 icms_update_allocation_limits(); | |
2784 } | |
2785 | |
2786 bitMapLock()->unlock(); | |
2787 releaseFreelistLocks(); | |
2788 | |
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2789 if (!CleanChunkPoolAsync) { |
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2790 Chunk::clean_chunk_pool(); |
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2791 } |
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2792 |
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2793 set_did_compact(false); |
0 | 2794 _between_prologue_and_epilogue = false; // ready for next cycle |
2795 } | |
2796 | |
2797 void ConcurrentMarkSweepGeneration::gc_epilogue(bool full) { | |
2798 collector()->gc_epilogue(full); | |
2799 | |
2800 // Also reset promotion tracking in par gc thread states. | |
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2801 if (CollectedHeap::use_parallel_gc_threads()) { |
0 | 2802 for (uint i = 0; i < ParallelGCThreads; i++) { |
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2803 _par_gc_thread_states[i]->promo.stopTrackingPromotions(i); |
0 | 2804 } |
2805 } | |
2806 } | |
2807 | |
2808 void ConcurrentMarkSweepGeneration::gc_epilogue_work(bool full) { | |
2809 assert(!incremental_collection_failed(), "Should have been cleared"); | |
2810 cmsSpace()->setPreconsumptionDirtyCardClosure(NULL); | |
2811 cmsSpace()->gc_epilogue(); | |
2812 // Print stat counters | |
2813 NOT_PRODUCT( | |
2814 assert(_numObjectsAllocated == 0, "check"); | |
2815 assert(_numWordsAllocated == 0, "check"); | |
2816 if (Verbose && PrintGC) { | |
2817 gclog_or_tty->print("Promoted "SIZE_FORMAT" objects, " | |
2818 SIZE_FORMAT" bytes", | |
2819 _numObjectsPromoted, _numWordsPromoted*sizeof(HeapWord)); | |
2820 } | |
2821 _numObjectsPromoted = 0; | |
2822 _numWordsPromoted = 0; | |
2823 ) | |
2824 | |
2825 if (PrintGC && Verbose) { | |
2826 // Call down the chain in contiguous_available needs the freelistLock | |
2827 // so print this out before releasing the freeListLock. | |
2828 gclog_or_tty->print(" Contiguous available "SIZE_FORMAT" bytes ", | |
2829 contiguous_available()); | |
2830 } | |
2831 } | |
2832 | |
2833 #ifndef PRODUCT | |
2834 bool CMSCollector::have_cms_token() { | |
2835 Thread* thr = Thread::current(); | |
2836 if (thr->is_VM_thread()) { | |
2837 return ConcurrentMarkSweepThread::vm_thread_has_cms_token(); | |
2838 } else if (thr->is_ConcurrentGC_thread()) { | |
2839 return ConcurrentMarkSweepThread::cms_thread_has_cms_token(); | |
2840 } else if (thr->is_GC_task_thread()) { | |
2841 return ConcurrentMarkSweepThread::vm_thread_has_cms_token() && | |
2842 ParGCRareEvent_lock->owned_by_self(); | |
2843 } | |
2844 return false; | |
2845 } | |
2846 #endif | |
2847 | |
2848 // Check reachability of the given heap address in CMS generation, | |
2849 // treating all other generations as roots. | |
2850 bool CMSCollector::is_cms_reachable(HeapWord* addr) { | |
2851 // We could "guarantee" below, rather than assert, but i'll | |
2852 // leave these as "asserts" so that an adventurous debugger | |
2853 // could try this in the product build provided some subset of | |
2854 // the conditions were met, provided they were intersted in the | |
2855 // results and knew that the computation below wouldn't interfere | |
2856 // with other concurrent computations mutating the structures | |
2857 // being read or written. | |
2858 assert(SafepointSynchronize::is_at_safepoint(), | |
2859 "Else mutations in object graph will make answer suspect"); | |
2860 assert(have_cms_token(), "Should hold cms token"); | |
2861 assert(haveFreelistLocks(), "must hold free list locks"); | |
2862 assert_lock_strong(bitMapLock()); | |
2863 | |
2864 // Clear the marking bit map array before starting, but, just | |
2865 // for kicks, first report if the given address is already marked | |
2866 gclog_or_tty->print_cr("Start: Address 0x%x is%s marked", addr, | |
2867 _markBitMap.isMarked(addr) ? "" : " not"); | |
2868 | |
2869 if (verify_after_remark()) { | |
2870 MutexLockerEx x(verification_mark_bm()->lock(), Mutex::_no_safepoint_check_flag); | |
2871 bool result = verification_mark_bm()->isMarked(addr); | |
2872 gclog_or_tty->print_cr("TransitiveMark: Address 0x%x %s marked", addr, | |
2873 result ? "IS" : "is NOT"); | |
2874 return result; | |
2875 } else { | |
2876 gclog_or_tty->print_cr("Could not compute result"); | |
2877 return false; | |
2878 } | |
2879 } | |
2880 | |
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2881 |
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2882 void |
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2883 CMSCollector::print_on_error(outputStream* st) { |
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2884 CMSCollector* collector = ConcurrentMarkSweepGeneration::_collector; |
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2885 if (collector != NULL) { |
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2886 CMSBitMap* bitmap = &collector->_markBitMap; |
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2887 st->print_cr("Marking Bits: (CMSBitMap*) " PTR_FORMAT, bitmap); |
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2888 bitmap->print_on_error(st, " Bits: "); |
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2889 |
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2890 st->cr(); |
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2891 |
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2892 CMSBitMap* mut_bitmap = &collector->_modUnionTable; |
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2893 st->print_cr("Mod Union Table: (CMSBitMap*) " PTR_FORMAT, mut_bitmap); |
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2894 mut_bitmap->print_on_error(st, " Bits: "); |
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2895 } |
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2896 } |
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2897 |
0 | 2898 //////////////////////////////////////////////////////// |
2899 // CMS Verification Support | |
2900 //////////////////////////////////////////////////////// | |
2901 // Following the remark phase, the following invariant | |
2902 // should hold -- each object in the CMS heap which is | |
2903 // marked in markBitMap() should be marked in the verification_mark_bm(). | |
2904 | |
2905 class VerifyMarkedClosure: public BitMapClosure { | |
2906 CMSBitMap* _marks; | |
2907 bool _failed; | |
2908 | |
2909 public: | |
2910 VerifyMarkedClosure(CMSBitMap* bm): _marks(bm), _failed(false) {} | |
2911 | |
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2912 bool do_bit(size_t offset) { |
0 | 2913 HeapWord* addr = _marks->offsetToHeapWord(offset); |
2914 if (!_marks->isMarked(addr)) { | |
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2915 oop(addr)->print_on(gclog_or_tty); |
0 | 2916 gclog_or_tty->print_cr(" ("INTPTR_FORMAT" should have been marked)", addr); |
2917 _failed = true; | |
2918 } | |
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2919 return true; |
0 | 2920 } |
2921 | |
2922 bool failed() { return _failed; } | |
2923 }; | |
2924 | |
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2925 bool CMSCollector::verify_after_remark(bool silent) { |
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2926 if (!silent) gclog_or_tty->print(" [Verifying CMS Marking... "); |
0 | 2927 MutexLockerEx ml(verification_mark_bm()->lock(), Mutex::_no_safepoint_check_flag); |
2928 static bool init = false; | |
2929 | |
2930 assert(SafepointSynchronize::is_at_safepoint(), | |
2931 "Else mutations in object graph will make answer suspect"); | |
2932 assert(have_cms_token(), | |
2933 "Else there may be mutual interference in use of " | |
2934 " verification data structures"); | |
2935 assert(_collectorState > Marking && _collectorState <= Sweeping, | |
2936 "Else marking info checked here may be obsolete"); | |
2937 assert(haveFreelistLocks(), "must hold free list locks"); | |
2938 assert_lock_strong(bitMapLock()); | |
2939 | |
2940 | |
2941 // Allocate marking bit map if not already allocated | |
2942 if (!init) { // first time | |
2943 if (!verification_mark_bm()->allocate(_span)) { | |
2944 return false; | |
2945 } | |
2946 init = true; | |
2947 } | |
2948 | |
2949 assert(verification_mark_stack()->isEmpty(), "Should be empty"); | |
2950 | |
2951 // Turn off refs discovery -- so we will be tracing through refs. | |
2952 // This is as intended, because by this time | |
2953 // GC must already have cleared any refs that need to be cleared, | |
2954 // and traced those that need to be marked; moreover, | |
2955 // the marking done here is not going to intefere in any | |
2956 // way with the marking information used by GC. | |
2957 NoRefDiscovery no_discovery(ref_processor()); | |
2958 | |
2959 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact;) | |
2960 | |
2961 // Clear any marks from a previous round | |
2962 verification_mark_bm()->clear_all(); | |
2963 assert(verification_mark_stack()->isEmpty(), "markStack should be empty"); | |
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2964 verify_work_stacks_empty(); |
0 | 2965 |
2966 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
2967 gch->ensure_parsability(false); // fill TLABs, but no need to retire them | |
2968 // Update the saved marks which may affect the root scans. | |
2969 gch->save_marks(); | |
2970 | |
2971 if (CMSRemarkVerifyVariant == 1) { | |
2972 // In this first variant of verification, we complete | |
2973 // all marking, then check if the new marks-verctor is | |
2974 // a subset of the CMS marks-vector. | |
2975 verify_after_remark_work_1(); | |
2976 } else if (CMSRemarkVerifyVariant == 2) { | |
2977 // In this second variant of verification, we flag an error | |
2978 // (i.e. an object reachable in the new marks-vector not reachable | |
2979 // in the CMS marks-vector) immediately, also indicating the | |
2980 // identify of an object (A) that references the unmarked object (B) -- | |
2981 // presumably, a mutation to A failed to be picked up by preclean/remark? | |
2982 verify_after_remark_work_2(); | |
2983 } else { | |
2984 warning("Unrecognized value %d for CMSRemarkVerifyVariant", | |
2985 CMSRemarkVerifyVariant); | |
2986 } | |
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2987 if (!silent) gclog_or_tty->print(" done] "); |
0 | 2988 return true; |
2989 } | |
2990 | |
2991 void CMSCollector::verify_after_remark_work_1() { | |
2992 ResourceMark rm; | |
2993 HandleMark hm; | |
2994 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
2995 | |
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2996 // Get a clear set of claim bits for the strong roots processing to work with. |
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2997 ClassLoaderDataGraph::clear_claimed_marks(); |
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2998 |
0 | 2999 // Mark from roots one level into CMS |
994
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3000 MarkRefsIntoClosure notOlder(_span, verification_mark_bm()); |
0 | 3001 gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel. |
3002 | |
3003 gch->gen_process_strong_roots(_cmsGen->level(), | |
3004 true, // younger gens are roots | |
989
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3005 true, // activate StrongRootsScope |
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3006 false, // not scavenging |
0 | 3007 SharedHeap::ScanningOption(roots_scanning_options()), |
989
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3008 ¬Older, |
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3009 true, // walk code active on stacks |
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3010 NULL, |
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3011 NULL); // SSS: Provide correct closure |
0 | 3012 |
3013 // Now mark from the roots | |
3014 MarkFromRootsClosure markFromRootsClosure(this, _span, | |
6725
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3015 verification_mark_bm(), verification_mark_stack(), |
0 | 3016 false /* don't yield */, true /* verifying */); |
3017 assert(_restart_addr == NULL, "Expected pre-condition"); | |
3018 verification_mark_bm()->iterate(&markFromRootsClosure); | |
3019 while (_restart_addr != NULL) { | |
3020 // Deal with stack overflow: by restarting at the indicated | |
3021 // address. | |
3022 HeapWord* ra = _restart_addr; | |
3023 markFromRootsClosure.reset(ra); | |
3024 _restart_addr = NULL; | |
3025 verification_mark_bm()->iterate(&markFromRootsClosure, ra, _span.end()); | |
3026 } | |
3027 assert(verification_mark_stack()->isEmpty(), "Should have been drained"); | |
3028 verify_work_stacks_empty(); | |
3029 | |
3030 // Marking completed -- now verify that each bit marked in | |
3031 // verification_mark_bm() is also marked in markBitMap(); flag all | |
3032 // errors by printing corresponding objects. | |
3033 VerifyMarkedClosure vcl(markBitMap()); | |
3034 verification_mark_bm()->iterate(&vcl); | |
3035 if (vcl.failed()) { | |
3036 gclog_or_tty->print("Verification failed"); | |
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3037 Universe::heap()->print_on(gclog_or_tty); |
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3038 fatal("CMS: failed marking verification after remark"); |
0 | 3039 } |
3040 } | |
3041 | |
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3042 class VerifyKlassOopsKlassClosure : public KlassClosure { |
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3043 class VerifyKlassOopsClosure : public OopClosure { |
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3044 CMSBitMap* _bitmap; |
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3045 public: |
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3046 VerifyKlassOopsClosure(CMSBitMap* bitmap) : _bitmap(bitmap) { } |
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3047 void do_oop(oop* p) { guarantee(*p == NULL || _bitmap->isMarked((HeapWord*) *p), "Should be marked"); } |
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3048 void do_oop(narrowOop* p) { ShouldNotReachHere(); } |
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3049 } _oop_closure; |
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3050 public: |
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3051 VerifyKlassOopsKlassClosure(CMSBitMap* bitmap) : _oop_closure(bitmap) {} |
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3052 void do_klass(Klass* k) { |
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3053 k->oops_do(&_oop_closure); |
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3054 } |
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3055 }; |
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3056 |
0 | 3057 void CMSCollector::verify_after_remark_work_2() { |
3058 ResourceMark rm; | |
3059 HandleMark hm; | |
3060 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
3061 | |
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3062 // Get a clear set of claim bits for the strong roots processing to work with. |
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3063 ClassLoaderDataGraph::clear_claimed_marks(); |
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3064 |
0 | 3065 // Mark from roots one level into CMS |
3066 MarkRefsIntoVerifyClosure notOlder(_span, verification_mark_bm(), | |
994
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3067 markBitMap()); |
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3068 CMKlassClosure klass_closure(¬Older); |
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3069 |
0 | 3070 gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel. |
3071 gch->gen_process_strong_roots(_cmsGen->level(), | |
3072 true, // younger gens are roots | |
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3073 true, // activate StrongRootsScope |
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3074 false, // not scavenging |
0 | 3075 SharedHeap::ScanningOption(roots_scanning_options()), |
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3076 ¬Older, |
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3077 true, // walk code active on stacks |
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3078 NULL, |
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3079 &klass_closure); |
0 | 3080 |
3081 // Now mark from the roots | |
3082 MarkFromRootsVerifyClosure markFromRootsClosure(this, _span, | |
3083 verification_mark_bm(), markBitMap(), verification_mark_stack()); | |
3084 assert(_restart_addr == NULL, "Expected pre-condition"); | |
3085 verification_mark_bm()->iterate(&markFromRootsClosure); | |
3086 while (_restart_addr != NULL) { | |
3087 // Deal with stack overflow: by restarting at the indicated | |
3088 // address. | |
3089 HeapWord* ra = _restart_addr; | |
3090 markFromRootsClosure.reset(ra); | |
3091 _restart_addr = NULL; | |
3092 verification_mark_bm()->iterate(&markFromRootsClosure, ra, _span.end()); | |
3093 } | |
3094 assert(verification_mark_stack()->isEmpty(), "Should have been drained"); | |
3095 verify_work_stacks_empty(); | |
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3096 |
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3097 VerifyKlassOopsKlassClosure verify_klass_oops(verification_mark_bm()); |
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3098 ClassLoaderDataGraph::classes_do(&verify_klass_oops); |
0 | 3099 |
3100 // Marking completed -- now verify that each bit marked in | |
3101 // verification_mark_bm() is also marked in markBitMap(); flag all | |
3102 // errors by printing corresponding objects. | |
3103 VerifyMarkedClosure vcl(markBitMap()); | |
3104 verification_mark_bm()->iterate(&vcl); | |
3105 assert(!vcl.failed(), "Else verification above should not have succeeded"); | |
3106 } | |
3107 | |
3108 void ConcurrentMarkSweepGeneration::save_marks() { | |
3109 // delegate to CMS space | |
3110 cmsSpace()->save_marks(); | |
3111 for (uint i = 0; i < ParallelGCThreads; i++) { | |
3112 _par_gc_thread_states[i]->promo.startTrackingPromotions(); | |
3113 } | |
3114 } | |
3115 | |
3116 bool ConcurrentMarkSweepGeneration::no_allocs_since_save_marks() { | |
3117 return cmsSpace()->no_allocs_since_save_marks(); | |
3118 } | |
3119 | |
3120 #define CMS_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \ | |
3121 \ | |
3122 void ConcurrentMarkSweepGeneration:: \ | |
3123 oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) { \ | |
3124 cl->set_generation(this); \ | |
3125 cmsSpace()->oop_since_save_marks_iterate##nv_suffix(cl); \ | |
3126 cl->reset_generation(); \ | |
3127 save_marks(); \ | |
3128 } | |
3129 | |
3130 ALL_SINCE_SAVE_MARKS_CLOSURES(CMS_SINCE_SAVE_MARKS_DEFN) | |
3131 | |
3132 void | |
3133 ConcurrentMarkSweepGeneration::object_iterate_since_last_GC(ObjectClosure* blk) | |
3134 { | |
3135 // Not currently implemented; need to do the following. -- ysr. | |
3136 // dld -- I think that is used for some sort of allocation profiler. So it | |
3137 // really means the objects allocated by the mutator since the last | |
3138 // GC. We could potentially implement this cheaply by recording only | |
3139 // the direct allocations in a side data structure. | |
3140 // | |
3141 // I think we probably ought not to be required to support these | |
3142 // iterations at any arbitrary point; I think there ought to be some | |
3143 // call to enable/disable allocation profiling in a generation/space, | |
3144 // and the iterator ought to return the objects allocated in the | |
3145 // gen/space since the enable call, or the last iterator call (which | |
3146 // will probably be at a GC.) That way, for gens like CM&S that would | |
3147 // require some extra data structure to support this, we only pay the | |
3148 // cost when it's in use... | |
3149 cmsSpace()->object_iterate_since_last_GC(blk); | |
3150 } | |
3151 | |
3152 void | |
3153 ConcurrentMarkSweepGeneration::younger_refs_iterate(OopsInGenClosure* cl) { | |
3154 cl->set_generation(this); | |
3155 younger_refs_in_space_iterate(_cmsSpace, cl); | |
3156 cl->reset_generation(); | |
3157 } | |
3158 | |
3159 void | |
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3160 ConcurrentMarkSweepGeneration::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) { |
0 | 3161 if (freelistLock()->owned_by_self()) { |
3162 Generation::oop_iterate(mr, cl); | |
3163 } else { | |
3164 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
3165 Generation::oop_iterate(mr, cl); | |
3166 } | |
3167 } | |
3168 | |
3169 void | |
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3170 ConcurrentMarkSweepGeneration::oop_iterate(ExtendedOopClosure* cl) { |
0 | 3171 if (freelistLock()->owned_by_self()) { |
3172 Generation::oop_iterate(cl); | |
3173 } else { | |
3174 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
3175 Generation::oop_iterate(cl); | |
3176 } | |
3177 } | |
3178 | |
3179 void | |
3180 ConcurrentMarkSweepGeneration::object_iterate(ObjectClosure* cl) { | |
3181 if (freelistLock()->owned_by_self()) { | |
3182 Generation::object_iterate(cl); | |
3183 } else { | |
3184 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
3185 Generation::object_iterate(cl); | |
3186 } | |
3187 } | |
3188 | |
3189 void | |
517
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3190 ConcurrentMarkSweepGeneration::safe_object_iterate(ObjectClosure* cl) { |
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3191 if (freelistLock()->owned_by_self()) { |
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3192 Generation::safe_object_iterate(cl); |
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3193 } else { |
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3194 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); |
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3195 Generation::safe_object_iterate(cl); |
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3196 } |
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3197 } |
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3198 |
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3199 void |
0 | 3200 ConcurrentMarkSweepGeneration::post_compact() { |
3201 } | |
3202 | |
3203 void | |
3204 ConcurrentMarkSweepGeneration::prepare_for_verify() { | |
3205 // Fix the linear allocation blocks to look like free blocks. | |
3206 | |
3207 // Locks are normally acquired/released in gc_prologue/gc_epilogue, but those | |
3208 // are not called when the heap is verified during universe initialization and | |
3209 // at vm shutdown. | |
3210 if (freelistLock()->owned_by_self()) { | |
3211 cmsSpace()->prepare_for_verify(); | |
3212 } else { | |
3213 MutexLockerEx fll(freelistLock(), Mutex::_no_safepoint_check_flag); | |
3214 cmsSpace()->prepare_for_verify(); | |
3215 } | |
3216 } | |
3217 | |
3218 void | |
6008 | 3219 ConcurrentMarkSweepGeneration::verify() { |
0 | 3220 // Locks are normally acquired/released in gc_prologue/gc_epilogue, but those |
3221 // are not called when the heap is verified during universe initialization and | |
3222 // at vm shutdown. | |
3223 if (freelistLock()->owned_by_self()) { | |
6008 | 3224 cmsSpace()->verify(); |
0 | 3225 } else { |
3226 MutexLockerEx fll(freelistLock(), Mutex::_no_safepoint_check_flag); | |
6008 | 3227 cmsSpace()->verify(); |
3228 } | |
3229 } | |
3230 | |
3231 void CMSCollector::verify() { | |
3232 _cmsGen->verify(); | |
0 | 3233 } |
3234 | |
3235 #ifndef PRODUCT | |
3236 bool CMSCollector::overflow_list_is_empty() const { | |
3237 assert(_num_par_pushes >= 0, "Inconsistency"); | |
3238 if (_overflow_list == NULL) { | |
3239 assert(_num_par_pushes == 0, "Inconsistency"); | |
3240 } | |
3241 return _overflow_list == NULL; | |
3242 } | |
3243 | |
3244 // The methods verify_work_stacks_empty() and verify_overflow_empty() | |
3245 // merely consolidate assertion checks that appear to occur together frequently. | |
3246 void CMSCollector::verify_work_stacks_empty() const { | |
3247 assert(_markStack.isEmpty(), "Marking stack should be empty"); | |
3248 assert(overflow_list_is_empty(), "Overflow list should be empty"); | |
3249 } | |
3250 | |
3251 void CMSCollector::verify_overflow_empty() const { | |
3252 assert(overflow_list_is_empty(), "Overflow list should be empty"); | |
3253 assert(no_preserved_marks(), "No preserved marks"); | |
3254 } | |
3255 #endif // PRODUCT | |
3256 | |
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3257 // Decide if we want to enable class unloading as part of the |
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3258 // ensuing concurrent GC cycle. We will collect and |
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3259 // unload classes if it's the case that: |
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3260 // (1) an explicit gc request has been made and the flag |
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3261 // ExplicitGCInvokesConcurrentAndUnloadsClasses is set, OR |
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3262 // (2) (a) class unloading is enabled at the command line, and |
6725
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3263 // (b) old gen is getting really full |
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3264 // NOTE: Provided there is no change in the state of the heap between |
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3265 // calls to this method, it should have idempotent results. Moreover, |
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3266 // its results should be monotonically increasing (i.e. going from 0 to 1, |
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3267 // but not 1 to 0) between successive calls between which the heap was |
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3268 // not collected. For the implementation below, it must thus rely on |
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3269 // the property that concurrent_cycles_since_last_unload() |
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3270 // will not decrease unless a collection cycle happened and that |
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3271 // _cmsGen->is_too_full() are |
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3272 // themselves also monotonic in that sense. See check_monotonicity() |
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3273 // below. |
6725
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3274 void CMSCollector::update_should_unload_classes() { |
94
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3275 _should_unload_classes = false; |
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3276 // Condition 1 above |
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3277 if (_full_gc_requested && ExplicitGCInvokesConcurrentAndUnloadsClasses) { |
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3278 _should_unload_classes = true; |
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3279 } else if (CMSClassUnloadingEnabled) { // Condition 2.a above |
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3280 // Disjuncts 2.b.(i,ii,iii) above |
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3281 _should_unload_classes = (concurrent_cycles_since_last_unload() >= |
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3282 CMSClassUnloadingMaxInterval) |
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3283 || _cmsGen->is_too_full(); |
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3284 } |
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3285 } |
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3286 |
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3287 bool ConcurrentMarkSweepGeneration::is_too_full() const { |
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3288 bool res = should_concurrent_collect(); |
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3289 res = res && (occupancy() > (double)CMSIsTooFullPercentage/100.0); |
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3290 return res; |
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3291 } |
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3292 |
0 | 3293 void CMSCollector::setup_cms_unloading_and_verification_state() { |
3293
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3294 const bool should_verify = VerifyBeforeGC || VerifyAfterGC || VerifyDuringGC |
0 | 3295 || VerifyBeforeExit; |
3293
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3296 const int rso = SharedHeap::SO_Strings | SharedHeap::SO_CodeCache; |
0 | 3297 |
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3298 if (should_unload_classes()) { // Should unload classes this cycle |
0 | 3299 remove_root_scanning_option(rso); // Shrink the root set appropriately |
3300 set_verifying(should_verify); // Set verification state for this cycle | |
3301 return; // Nothing else needs to be done at this time | |
3302 } | |
3303 | |
3304 // Not unloading classes this cycle | |
94
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3305 assert(!should_unload_classes(), "Inconsitency!"); |
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3306 if ((!verifying() || unloaded_classes_last_cycle()) && should_verify) { |
0 | 3307 // Include symbols, strings and code cache elements to prevent their resurrection. |
3308 add_root_scanning_option(rso); | |
3309 set_verifying(true); | |
3310 } else if (verifying() && !should_verify) { | |
3311 // We were verifying, but some verification flags got disabled. | |
3312 set_verifying(false); | |
3313 // Exclude symbols, strings and code cache elements from root scanning to | |
3314 // reduce IM and RM pauses. | |
3315 remove_root_scanning_option(rso); | |
3316 } | |
3317 } | |
3318 | |
3319 | |
3320 #ifndef PRODUCT | |
3321 HeapWord* CMSCollector::block_start(const void* p) const { | |
3322 const HeapWord* addr = (HeapWord*)p; | |
3323 if (_span.contains(p)) { | |
3324 if (_cmsGen->cmsSpace()->is_in_reserved(addr)) { | |
3325 return _cmsGen->cmsSpace()->block_start(p); | |
3326 } | |
3327 } | |
3328 return NULL; | |
3329 } | |
3330 #endif | |
3331 | |
3332 HeapWord* | |
3333 ConcurrentMarkSweepGeneration::expand_and_allocate(size_t word_size, | |
3334 bool tlab, | |
3335 bool parallel) { | |
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3336 CMSSynchronousYieldRequest yr; |
0 | 3337 assert(!tlab, "Can't deal with TLAB allocation"); |
3338 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
3339 expand(word_size*HeapWordSize, MinHeapDeltaBytes, | |
3340 CMSExpansionCause::_satisfy_allocation); | |
3341 if (GCExpandToAllocateDelayMillis > 0) { | |
3342 os::sleep(Thread::current(), GCExpandToAllocateDelayMillis, false); | |
3343 } | |
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3344 return have_lock_and_allocate(word_size, tlab); |
0 | 3345 } |
3346 | |
3347 // YSR: All of this generation expansion/shrinking stuff is an exact copy of | |
3348 // OneContigSpaceCardGeneration, which makes me wonder if we should move this | |
3349 // to CardGeneration and share it... | |
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3350 bool ConcurrentMarkSweepGeneration::expand(size_t bytes, size_t expand_bytes) { |
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3351 return CardGeneration::expand(bytes, expand_bytes); |
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3352 } |
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3353 |
0 | 3354 void ConcurrentMarkSweepGeneration::expand(size_t bytes, size_t expand_bytes, |
3355 CMSExpansionCause::Cause cause) | |
3356 { | |
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3357 |
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3358 bool success = expand(bytes, expand_bytes); |
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3359 |
0 | 3360 // remember why we expanded; this information is used |
3361 // by shouldConcurrentCollect() when making decisions on whether to start | |
3362 // a new CMS cycle. | |
3363 if (success) { | |
3364 set_expansion_cause(cause); | |
3365 if (PrintGCDetails && Verbose) { | |
3366 gclog_or_tty->print_cr("Expanded CMS gen for %s", | |
3367 CMSExpansionCause::to_string(cause)); | |
3368 } | |
3369 } | |
3370 } | |
3371 | |
3372 HeapWord* ConcurrentMarkSweepGeneration::expand_and_par_lab_allocate(CMSParGCThreadState* ps, size_t word_sz) { | |
3373 HeapWord* res = NULL; | |
3374 MutexLocker x(ParGCRareEvent_lock); | |
3375 while (true) { | |
3376 // Expansion by some other thread might make alloc OK now: | |
3377 res = ps->lab.alloc(word_sz); | |
3378 if (res != NULL) return res; | |
3379 // If there's not enough expansion space available, give up. | |
3380 if (_virtual_space.uncommitted_size() < (word_sz * HeapWordSize)) { | |
3381 return NULL; | |
3382 } | |
3383 // Otherwise, we try expansion. | |
3384 expand(word_sz*HeapWordSize, MinHeapDeltaBytes, | |
3385 CMSExpansionCause::_allocate_par_lab); | |
3386 // Now go around the loop and try alloc again; | |
3387 // A competing par_promote might beat us to the expansion space, | |
3388 // so we may go around the loop again if promotion fails agaion. | |
3389 if (GCExpandToAllocateDelayMillis > 0) { | |
3390 os::sleep(Thread::current(), GCExpandToAllocateDelayMillis, false); | |
3391 } | |
3392 } | |
3393 } | |
3394 | |
3395 | |
3396 bool ConcurrentMarkSweepGeneration::expand_and_ensure_spooling_space( | |
3397 PromotionInfo* promo) { | |
3398 MutexLocker x(ParGCRareEvent_lock); | |
3399 size_t refill_size_bytes = promo->refillSize() * HeapWordSize; | |
3400 while (true) { | |
3401 // Expansion by some other thread might make alloc OK now: | |
3402 if (promo->ensure_spooling_space()) { | |
3403 assert(promo->has_spooling_space(), | |
3404 "Post-condition of successful ensure_spooling_space()"); | |
3405 return true; | |
3406 } | |
3407 // If there's not enough expansion space available, give up. | |
3408 if (_virtual_space.uncommitted_size() < refill_size_bytes) { | |
3409 return false; | |
3410 } | |
3411 // Otherwise, we try expansion. | |
3412 expand(refill_size_bytes, MinHeapDeltaBytes, | |
3413 CMSExpansionCause::_allocate_par_spooling_space); | |
3414 // Now go around the loop and try alloc again; | |
3415 // A competing allocation might beat us to the expansion space, | |
3416 // so we may go around the loop again if allocation fails again. | |
3417 if (GCExpandToAllocateDelayMillis > 0) { | |
3418 os::sleep(Thread::current(), GCExpandToAllocateDelayMillis, false); | |
3419 } | |
3420 } | |
3421 } | |
3422 | |
3423 | |
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3424 void ConcurrentMarkSweepGeneration::shrink_by(size_t bytes) { |
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3425 assert_locked_or_safepoint(ExpandHeap_lock); |
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3426 // Shrink committed space |
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3427 _virtual_space.shrink_by(bytes); |
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3428 // Shrink space; this also shrinks the space's BOT |
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3429 _cmsSpace->set_end((HeapWord*) _virtual_space.high()); |
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3430 size_t new_word_size = heap_word_size(_cmsSpace->capacity()); |
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3431 // Shrink the shared block offset array |
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3432 _bts->resize(new_word_size); |
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3433 MemRegion mr(_cmsSpace->bottom(), new_word_size); |
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3434 // Shrink the card table |
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3435 Universe::heap()->barrier_set()->resize_covered_region(mr); |
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3436 |
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3437 if (Verbose && PrintGC) { |
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3438 size_t new_mem_size = _virtual_space.committed_size(); |
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3439 size_t old_mem_size = new_mem_size + bytes; |
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3440 gclog_or_tty->print_cr("Shrinking %s from " SIZE_FORMAT "K to " SIZE_FORMAT "K", |
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3441 name(), old_mem_size/K, new_mem_size/K); |
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3442 } |
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3443 } |
0 | 3444 |
3445 void ConcurrentMarkSweepGeneration::shrink(size_t bytes) { | |
3446 assert_locked_or_safepoint(Heap_lock); | |
3447 size_t size = ReservedSpace::page_align_size_down(bytes); | |
3448 if (size > 0) { | |
3449 shrink_by(size); | |
3450 } | |
3451 } | |
3452 | |
3453 bool ConcurrentMarkSweepGeneration::grow_by(size_t bytes) { | |
3454 assert_locked_or_safepoint(Heap_lock); | |
3455 bool result = _virtual_space.expand_by(bytes); | |
3456 if (result) { | |
3457 size_t new_word_size = | |
3458 heap_word_size(_virtual_space.committed_size()); | |
3459 MemRegion mr(_cmsSpace->bottom(), new_word_size); | |
3460 _bts->resize(new_word_size); // resize the block offset shared array | |
3461 Universe::heap()->barrier_set()->resize_covered_region(mr); | |
3462 // Hmmmm... why doesn't CFLS::set_end verify locking? | |
3463 // This is quite ugly; FIX ME XXX | |
1145
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3464 _cmsSpace->assert_locked(freelistLock()); |
0 | 3465 _cmsSpace->set_end((HeapWord*)_virtual_space.high()); |
3466 | |
3467 // update the space and generation capacity counters | |
3468 if (UsePerfData) { | |
3469 _space_counters->update_capacity(); | |
3470 _gen_counters->update_all(); | |
3471 } | |
3472 | |
3473 if (Verbose && PrintGC) { | |
3474 size_t new_mem_size = _virtual_space.committed_size(); | |
3475 size_t old_mem_size = new_mem_size - bytes; | |
7623
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7102489: RFE: cleanup jlong typedef on __APPLE__and _LLP64 systems.
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3476 gclog_or_tty->print_cr("Expanding %s from " SIZE_FORMAT "K by " SIZE_FORMAT "K to " SIZE_FORMAT "K", |
0 | 3477 name(), old_mem_size/K, bytes/K, new_mem_size/K); |
3478 } | |
3479 } | |
3480 return result; | |
3481 } | |
3482 | |
3483 bool ConcurrentMarkSweepGeneration::grow_to_reserved() { | |
3484 assert_locked_or_safepoint(Heap_lock); | |
3485 bool success = true; | |
3486 const size_t remaining_bytes = _virtual_space.uncommitted_size(); | |
3487 if (remaining_bytes > 0) { | |
3488 success = grow_by(remaining_bytes); | |
3489 DEBUG_ONLY(if (!success) warning("grow to reserved failed");) | |
3490 } | |
3491 return success; | |
3492 } | |
3493 | |
9072
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3494 void ConcurrentMarkSweepGeneration::shrink_free_list_by(size_t bytes) { |
0 | 3495 assert_locked_or_safepoint(Heap_lock); |
3496 assert_lock_strong(freelistLock()); | |
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3497 if (PrintGCDetails && Verbose) { |
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3498 warning("Shrinking of CMS not yet implemented"); |
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3499 } |
0 | 3500 return; |
3501 } | |
3502 | |
3503 | |
3504 // Simple ctor/dtor wrapper for accounting & timer chores around concurrent | |
3505 // phases. | |
3506 class CMSPhaseAccounting: public StackObj { | |
3507 public: | |
3508 CMSPhaseAccounting(CMSCollector *collector, | |
3509 const char *phase, | |
3510 bool print_cr = true); | |
3511 ~CMSPhaseAccounting(); | |
3512 | |
3513 private: | |
3514 CMSCollector *_collector; | |
3515 const char *_phase; | |
3516 elapsedTimer _wallclock; | |
3517 bool _print_cr; | |
3518 | |
3519 public: | |
3520 // Not MT-safe; so do not pass around these StackObj's | |
3521 // where they may be accessed by other threads. | |
3522 jlong wallclock_millis() { | |
3523 assert(_wallclock.is_active(), "Wall clock should not stop"); | |
3524 _wallclock.stop(); // to record time | |
3525 jlong ret = _wallclock.milliseconds(); | |
3526 _wallclock.start(); // restart | |
3527 return ret; | |
3528 } | |
3529 }; | |
3530 | |
3531 CMSPhaseAccounting::CMSPhaseAccounting(CMSCollector *collector, | |
3532 const char *phase, | |
3533 bool print_cr) : | |
3534 _collector(collector), _phase(phase), _print_cr(print_cr) { | |
3535 | |
3536 if (PrintCMSStatistics != 0) { | |
3537 _collector->resetYields(); | |
3538 } | |
8740
62609ffa2fc6
8008684: CMS: concurrent phase start markers should always be printed
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diff
changeset
|
3539 if (PrintGCDetails) { |
0 | 3540 gclog_or_tty->date_stamp(PrintGCDateStamps); |
8740
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3541 gclog_or_tty->stamp(PrintGCTimeStamps); |
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3542 gclog_or_tty->print_cr("[%s-concurrent-%s-start]", |
0 | 3543 _collector->cmsGen()->short_name(), _phase); |
3544 } | |
3545 _collector->resetTimer(); | |
3546 _wallclock.start(); | |
3547 _collector->startTimer(); | |
3548 } | |
3549 | |
3550 CMSPhaseAccounting::~CMSPhaseAccounting() { | |
3551 assert(_wallclock.is_active(), "Wall clock should not have stopped"); | |
3552 _collector->stopTimer(); | |
3553 _wallclock.stop(); | |
3554 if (PrintGCDetails) { | |
3555 gclog_or_tty->date_stamp(PrintGCDateStamps); | |
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9646b7ff4d14
7198130: G1: PrintReferenceGC output comes out of order
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diff
changeset
|
3556 gclog_or_tty->stamp(PrintGCTimeStamps); |
0 | 3557 gclog_or_tty->print("[%s-concurrent-%s: %3.3f/%3.3f secs]", |
3558 _collector->cmsGen()->short_name(), | |
3559 _phase, _collector->timerValue(), _wallclock.seconds()); | |
3560 if (_print_cr) { | |
3561 gclog_or_tty->print_cr(""); | |
3562 } | |
3563 if (PrintCMSStatistics != 0) { | |
3564 gclog_or_tty->print_cr(" (CMS-concurrent-%s yielded %d times)", _phase, | |
3565 _collector->yields()); | |
3566 } | |
3567 } | |
3568 } | |
3569 | |
3570 // CMS work | |
3571 | |
3572 // Checkpoint the roots into this generation from outside | |
3573 // this generation. [Note this initial checkpoint need only | |
3574 // be approximate -- we'll do a catch up phase subsequently.] | |
3575 void CMSCollector::checkpointRootsInitial(bool asynch) { | |
3576 assert(_collectorState == InitialMarking, "Wrong collector state"); | |
3577 check_correct_thread_executing(); | |
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
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3293
diff
changeset
|
3578 TraceCMSMemoryManagerStats tms(_collectorState,GenCollectedHeap::heap()->gc_cause()); |
2125
7246a374a9f2
6458402: 3 jvmti tests fail with CMS and +ExplicitGCInvokesConcurrent
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diff
changeset
|
3579 |
10405 | 3580 save_heap_summary(); |
3581 report_heap_summary(GCWhen::BeforeGC); | |
3582 | |
0 | 3583 ReferenceProcessor* rp = ref_processor(); |
3584 SpecializationStats::clear(); | |
3585 assert(_restart_addr == NULL, "Control point invariant"); | |
3586 if (asynch) { | |
3587 // acquire locks for subsequent manipulations | |
3588 MutexLockerEx x(bitMapLock(), | |
3589 Mutex::_no_safepoint_check_flag); | |
3590 checkpointRootsInitialWork(asynch); | |
3979
4dfb2df418f2
6484982: G1: process references during evacuation pauses
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parents:
3827
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changeset
|
3591 // enable ("weak") refs discovery |
4dfb2df418f2
6484982: G1: process references during evacuation pauses
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diff
changeset
|
3592 rp->enable_discovery(true /*verify_disabled*/, true /*check_no_refs*/); |
0 | 3593 _collectorState = Marking; |
3594 } else { | |
3595 // (Weak) Refs discovery: this is controlled from genCollectedHeap::do_collection | |
3596 // which recognizes if we are a CMS generation, and doesn't try to turn on | |
3597 // discovery; verify that they aren't meddling. | |
3598 assert(!rp->discovery_is_atomic(), | |
3599 "incorrect setting of discovery predicate"); | |
3600 assert(!rp->discovery_enabled(), "genCollectedHeap shouldn't control " | |
3601 "ref discovery for this generation kind"); | |
3602 // already have locks | |
3603 checkpointRootsInitialWork(asynch); | |
3979
4dfb2df418f2
6484982: G1: process references during evacuation pauses
johnc
parents:
3827
diff
changeset
|
3604 // now enable ("weak") refs discovery |
4dfb2df418f2
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3827
diff
changeset
|
3605 rp->enable_discovery(true /*verify_disabled*/, false /*verify_no_refs*/); |
0 | 3606 _collectorState = Marking; |
3607 } | |
3608 SpecializationStats::print(); | |
3609 } | |
3610 | |
3611 void CMSCollector::checkpointRootsInitialWork(bool asynch) { | |
3612 assert(SafepointSynchronize::is_at_safepoint(), "world should be stopped"); | |
3613 assert(_collectorState == InitialMarking, "just checking"); | |
3614 | |
3615 // If there has not been a GC[n-1] since last GC[n] cycle completed, | |
3616 // precede our marking with a collection of all | |
3617 // younger generations to keep floating garbage to a minimum. | |
3618 // XXX: we won't do this for now -- it's an optimization to be done later. | |
3619 | |
3620 // already have locks | |
3621 assert_lock_strong(bitMapLock()); | |
3622 assert(_markBitMap.isAllClear(), "was reset at end of previous cycle"); | |
3623 | |
3624 // Setup the verification and class unloading state for this | |
3625 // CMS collection cycle. | |
3626 setup_cms_unloading_and_verification_state(); | |
3627 | |
10405 | 3628 NOT_PRODUCT(GCTraceTime t("\ncheckpointRootsInitialWork", |
3629 PrintGCDetails && Verbose, true, _gc_timer_cm);) | |
0 | 3630 if (UseAdaptiveSizePolicy) { |
3631 size_policy()->checkpoint_roots_initial_begin(); | |
3632 } | |
3633 | |
3634 // Reset all the PLAB chunk arrays if necessary. | |
3635 if (_survivor_plab_array != NULL && !CMSPLABRecordAlways) { | |
3636 reset_survivor_plab_arrays(); | |
3637 } | |
3638 | |
3639 ResourceMark rm; | |
3640 HandleMark hm; | |
3641 | |
3642 FalseClosure falseClosure; | |
3643 // In the case of a synchronous collection, we will elide the | |
3644 // remark step, so it's important to catch all the nmethod oops | |
994
753cf9794df9
6885169: merge of 4957990 and 6863023 causes conflict on do_nmethods
jrose
parents:
993
diff
changeset
|
3645 // in this step. |
753cf9794df9
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diff
changeset
|
3646 // The final 'true' flag to gen_process_strong_roots will ensure this. |
753cf9794df9
6885169: merge of 4957990 and 6863023 causes conflict on do_nmethods
jrose
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diff
changeset
|
3647 // If 'async' is true, we can relax the nmethod tracing. |
753cf9794df9
6885169: merge of 4957990 and 6863023 causes conflict on do_nmethods
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diff
changeset
|
3648 MarkRefsIntoClosure notOlder(_span, &_markBitMap); |
0 | 3649 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
3650 | |
3651 verify_work_stacks_empty(); | |
3652 verify_overflow_empty(); | |
3653 | |
3654 gch->ensure_parsability(false); // fill TLABs, but no need to retire them | |
3655 // Update the saved marks which may affect the root scans. | |
3656 gch->save_marks(); | |
3657 | |
3658 // weak reference processing has not started yet. | |
3659 ref_processor()->set_enqueuing_is_done(false); | |
3660 | |
6725
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6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
3661 // Need to remember all newly created CLDs, |
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
3662 // so that we can guarantee that the remark finds them. |
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
3663 ClassLoaderDataGraph::remember_new_clds(true); |
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
3664 |
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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diff
changeset
|
3665 // Whenever a CLD is found, it will be claimed before proceeding to mark |
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
3666 // the klasses. The claimed marks need to be cleared before marking starts. |
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
3667 ClassLoaderDataGraph::clear_claimed_marks(); |
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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diff
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|
3668 |
da91efe96a93
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diff
changeset
|
3669 CMKlassClosure klass_closure(¬Older); |
0 | 3670 { |
3671 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact;) | |
3672 gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel. | |
3673 gch->gen_process_strong_roots(_cmsGen->level(), | |
3674 true, // younger gens are roots | |
989
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
3675 true, // activate StrongRootsScope |
6725
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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diff
changeset
|
3676 false, // not scavenging |
0 | 3677 SharedHeap::ScanningOption(roots_scanning_options()), |
989
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
3678 ¬Older, |
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
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diff
changeset
|
3679 true, // walk all of code cache if (so & SO_CodeCache) |
6725
da91efe96a93
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|
3680 NULL, |
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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diff
changeset
|
3681 &klass_closure); |
0 | 3682 } |
3683 | |
3684 // Clear mod-union table; it will be dirtied in the prologue of | |
3685 // CMS generation per each younger generation collection. | |
3686 | |
3687 assert(_modUnionTable.isAllClear(), | |
3688 "Was cleared in most recent final checkpoint phase" | |
3689 " or no bits are set in the gc_prologue before the start of the next " | |
3690 "subsequent marking phase."); | |
3691 | |
6725
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diff
changeset
|
3692 assert(_ct->klass_rem_set()->mod_union_is_clear(), "Must be"); |
da91efe96a93
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|
3693 |
0 | 3694 // Save the end of the used_region of the constituent generations |
3695 // to be used to limit the extent of sweep in each generation. | |
3696 save_sweep_limits(); | |
3697 if (UseAdaptiveSizePolicy) { | |
3698 size_policy()->checkpoint_roots_initial_end(gch->gc_cause()); | |
3699 } | |
3700 verify_overflow_empty(); | |
3701 } | |
3702 | |
3703 bool CMSCollector::markFromRoots(bool asynch) { | |
3704 // we might be tempted to assert that: | |
3705 // assert(asynch == !SafepointSynchronize::is_at_safepoint(), | |
3706 // "inconsistent argument?"); | |
3707 // However that wouldn't be right, because it's possible that | |
3708 // a safepoint is indeed in progress as a younger generation | |
3709 // stop-the-world GC happens even as we mark in this generation. | |
3710 assert(_collectorState == Marking, "inconsistent state?"); | |
3711 check_correct_thread_executing(); | |
3712 verify_overflow_empty(); | |
3713 | |
3714 bool res; | |
3715 if (asynch) { | |
3716 | |
3717 // Start the timers for adaptive size policy for the concurrent phases | |
3718 // Do it here so that the foreground MS can use the concurrent | |
3719 // timer since a foreground MS might has the sweep done concurrently | |
3720 // or STW. | |
3721 if (UseAdaptiveSizePolicy) { | |
3722 size_policy()->concurrent_marking_begin(); | |
3723 } | |
3724 | |
3725 // Weak ref discovery note: We may be discovering weak | |
3726 // refs in this generation concurrent (but interleaved) with | |
3727 // weak ref discovery by a younger generation collector. | |
3728 | |
3729 CMSTokenSyncWithLocks ts(true, bitMapLock()); | |
3730 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
3731 CMSPhaseAccounting pa(this, "mark", !PrintGCDetails); | |
3732 res = markFromRootsWork(asynch); | |
3733 if (res) { | |
3734 _collectorState = Precleaning; | |
3735 } else { // We failed and a foreground collection wants to take over | |
3736 assert(_foregroundGCIsActive, "internal state inconsistency"); | |
3737 assert(_restart_addr == NULL, "foreground will restart from scratch"); | |
3738 if (PrintGCDetails) { | |
3739 gclog_or_tty->print_cr("bailing out to foreground collection"); | |
3740 } | |
3741 } | |
3742 if (UseAdaptiveSizePolicy) { | |
3743 size_policy()->concurrent_marking_end(); | |
3744 } | |
3745 } else { | |
3746 assert(SafepointSynchronize::is_at_safepoint(), | |
3747 "inconsistent with asynch == false"); | |
3748 if (UseAdaptiveSizePolicy) { | |
3749 size_policy()->ms_collection_marking_begin(); | |
3750 } | |
3751 // already have locks | |
3752 res = markFromRootsWork(asynch); | |
3753 _collectorState = FinalMarking; | |
3754 if (UseAdaptiveSizePolicy) { | |
3755 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
3756 size_policy()->ms_collection_marking_end(gch->gc_cause()); | |
3757 } | |
3758 } | |
3759 verify_overflow_empty(); | |
3760 return res; | |
3761 } | |
3762 | |
3763 bool CMSCollector::markFromRootsWork(bool asynch) { | |
3764 // iterate over marked bits in bit map, doing a full scan and mark | |
3765 // from these roots using the following algorithm: | |
3766 // . if oop is to the right of the current scan pointer, | |
3767 // mark corresponding bit (we'll process it later) | |
3768 // . else (oop is to left of current scan pointer) | |
3769 // push oop on marking stack | |
3770 // . drain the marking stack | |
3771 | |
3772 // Note that when we do a marking step we need to hold the | |
3773 // bit map lock -- recall that direct allocation (by mutators) | |
3774 // and promotion (by younger generation collectors) is also | |
3775 // marking the bit map. [the so-called allocate live policy.] | |
3776 // Because the implementation of bit map marking is not | |
3777 // robust wrt simultaneous marking of bits in the same word, | |
3778 // we need to make sure that there is no such interference | |
3779 // between concurrent such updates. | |
3780 | |
3781 // already have locks | |
3782 assert_lock_strong(bitMapLock()); | |
3783 | |
3784 verify_work_stacks_empty(); | |
3785 verify_overflow_empty(); | |
3786 bool result = false; | |
1284 | 3787 if (CMSConcurrentMTEnabled && ConcGCThreads > 0) { |
0 | 3788 result = do_marking_mt(asynch); |
3789 } else { | |
3790 result = do_marking_st(asynch); | |
3791 } | |
3792 return result; | |
3793 } | |
3794 | |
3795 // Forward decl | |
3796 class CMSConcMarkingTask; | |
3797 | |
3798 class CMSConcMarkingTerminator: public ParallelTaskTerminator { | |
3799 CMSCollector* _collector; | |
3800 CMSConcMarkingTask* _task; | |
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3801 public: |
0 | 3802 virtual void yield(); |
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3803 |
0 | 3804 // "n_threads" is the number of threads to be terminated. |
3805 // "queue_set" is a set of work queues of other threads. | |
3806 // "collector" is the CMS collector associated with this task terminator. | |
3807 // "yield" indicates whether we need the gang as a whole to yield. | |
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3808 CMSConcMarkingTerminator(int n_threads, TaskQueueSetSuper* queue_set, CMSCollector* collector) : |
0 | 3809 ParallelTaskTerminator(n_threads, queue_set), |
1837
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3810 _collector(collector) { } |
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3811 |
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3812 void set_task(CMSConcMarkingTask* task) { |
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3813 _task = task; |
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3814 } |
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3815 }; |
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3816 |
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3817 class CMSConcMarkingTerminatorTerminator: public TerminatorTerminator { |
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3818 CMSConcMarkingTask* _task; |
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3819 public: |
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3820 bool should_exit_termination(); |
0 | 3821 void set_task(CMSConcMarkingTask* task) { |
3822 _task = task; | |
3823 } | |
3824 }; | |
3825 | |
3826 // MT Concurrent Marking Task | |
3827 class CMSConcMarkingTask: public YieldingFlexibleGangTask { | |
3828 CMSCollector* _collector; | |
3829 int _n_workers; // requested/desired # workers | |
3830 bool _asynch; | |
3831 bool _result; | |
3832 CompactibleFreeListSpace* _cms_space; | |
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3833 char _pad_front[64]; // padding to ... |
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3834 HeapWord* _global_finger; // ... avoid sharing cache line |
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3835 char _pad_back[64]; |
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3836 HeapWord* _restart_addr; |
0 | 3837 |
3838 // Exposed here for yielding support | |
3839 Mutex* const _bit_map_lock; | |
3840 | |
3841 // The per thread work queues, available here for stealing | |
3842 OopTaskQueueSet* _task_queues; | |
1837
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3843 |
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3844 // Termination (and yielding) support |
0 | 3845 CMSConcMarkingTerminator _term; |
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3846 CMSConcMarkingTerminatorTerminator _term_term; |
0 | 3847 |
3848 public: | |
3849 CMSConcMarkingTask(CMSCollector* collector, | |
3850 CompactibleFreeListSpace* cms_space, | |
1833
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3851 bool asynch, |
0 | 3852 YieldingFlexibleWorkGang* workers, |
3853 OopTaskQueueSet* task_queues): | |
3854 YieldingFlexibleGangTask("Concurrent marking done multi-threaded"), | |
3855 _collector(collector), | |
3856 _cms_space(cms_space), | |
1833
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3857 _asynch(asynch), _n_workers(0), _result(true), |
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3858 _task_queues(task_queues), |
1837
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3859 _term(_n_workers, task_queues, _collector), |
0 | 3860 _bit_map_lock(collector->bitMapLock()) |
3861 { | |
1833
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3862 _requested_size = _n_workers; |
0 | 3863 _term.set_task(this); |
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3864 _term_term.set_task(this); |
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3865 _restart_addr = _global_finger = _cms_space->bottom(); |
0 | 3866 } |
3867 | |
3868 | |
3869 OopTaskQueueSet* task_queues() { return _task_queues; } | |
3870 | |
3871 OopTaskQueue* work_queue(int i) { return task_queues()->queue(i); } | |
3872 | |
3873 HeapWord** global_finger_addr() { return &_global_finger; } | |
3874 | |
3875 CMSConcMarkingTerminator* terminator() { return &_term; } | |
3876 | |
1833
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3877 virtual void set_for_termination(int active_workers) { |
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3878 terminator()->reset_for_reuse(active_workers); |
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3879 } |
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3880 |
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3881 void work(uint worker_id); |
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3882 bool should_yield() { |
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3883 return ConcurrentMarkSweepThread::should_yield() |
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3884 && !_collector->foregroundGCIsActive() |
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3885 && _asynch; |
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3886 } |
0 | 3887 |
3888 virtual void coordinator_yield(); // stuff done by coordinator | |
3889 bool result() { return _result; } | |
3890 | |
3891 void reset(HeapWord* ra) { | |
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3892 assert(_global_finger >= _cms_space->end(), "Postcondition of ::work(i)"); |
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3893 _restart_addr = _global_finger = ra; |
0 | 3894 _term.reset_for_reuse(); |
3895 } | |
3896 | |
3897 static bool get_work_from_overflow_stack(CMSMarkStack* ovflw_stk, | |
3898 OopTaskQueue* work_q); | |
3899 | |
3900 private: | |
3901 void do_scan_and_mark(int i, CompactibleFreeListSpace* sp); | |
3902 void do_work_steal(int i); | |
3903 void bump_global_finger(HeapWord* f); | |
3904 }; | |
3905 | |
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3906 bool CMSConcMarkingTerminatorTerminator::should_exit_termination() { |
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3907 assert(_task != NULL, "Error"); |
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3908 return _task->yielding(); |
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3909 // Note that we do not need the disjunct || _task->should_yield() above |
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3910 // because we want terminating threads to yield only if the task |
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3911 // is already in the midst of yielding, which happens only after at least one |
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3912 // thread has yielded. |
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3913 } |
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3914 |
0 | 3915 void CMSConcMarkingTerminator::yield() { |
1837
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3916 if (_task->should_yield()) { |
0 | 3917 _task->yield(); |
3918 } else { | |
3919 ParallelTaskTerminator::yield(); | |
3920 } | |
3921 } | |
3922 | |
3923 //////////////////////////////////////////////////////////////// | |
3924 // Concurrent Marking Algorithm Sketch | |
3925 //////////////////////////////////////////////////////////////// | |
3926 // Until all tasks exhausted (both spaces): | |
3927 // -- claim next available chunk | |
3928 // -- bump global finger via CAS | |
3929 // -- find first object that starts in this chunk | |
3930 // and start scanning bitmap from that position | |
3931 // -- scan marked objects for oops | |
3932 // -- CAS-mark target, and if successful: | |
3933 // . if target oop is above global finger (volatile read) | |
3934 // nothing to do | |
3935 // . if target oop is in chunk and above local finger | |
3936 // then nothing to do | |
3937 // . else push on work-queue | |
3938 // -- Deal with possible overflow issues: | |
3939 // . local work-queue overflow causes stuff to be pushed on | |
3940 // global (common) overflow queue | |
3941 // . always first empty local work queue | |
3942 // . then get a batch of oops from global work queue if any | |
3943 // . then do work stealing | |
3944 // -- When all tasks claimed (both spaces) | |
3945 // and local work queue empty, | |
3946 // then in a loop do: | |
3947 // . check global overflow stack; steal a batch of oops and trace | |
3948 // . try to steal from other threads oif GOS is empty | |
3949 // . if neither is available, offer termination | |
3950 // -- Terminate and return result | |
3951 // | |
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3952 void CMSConcMarkingTask::work(uint worker_id) { |
0 | 3953 elapsedTimer _timer; |
3954 ResourceMark rm; | |
3955 HandleMark hm; | |
3956 | |
3957 DEBUG_ONLY(_collector->verify_overflow_empty();) | |
3958 | |
3959 // Before we begin work, our work queue should be empty | |
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3960 assert(work_queue(worker_id)->size() == 0, "Expected to be empty"); |
0 | 3961 // Scan the bitmap covering _cms_space, tracing through grey objects. |
3962 _timer.start(); | |
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3963 do_scan_and_mark(worker_id, _cms_space); |
0 | 3964 _timer.stop(); |
3965 if (PrintCMSStatistics != 0) { | |
3966 gclog_or_tty->print_cr("Finished cms space scanning in %dth thread: %3.3f sec", | |
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3967 worker_id, _timer.seconds()); |
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3968 // XXX: need xxx/xxx type of notation, two timers |
0 | 3969 } |
3970 | |
3971 // ... do work stealing | |
3972 _timer.reset(); | |
3973 _timer.start(); | |
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3974 do_work_steal(worker_id); |
0 | 3975 _timer.stop(); |
3976 if (PrintCMSStatistics != 0) { | |
3977 gclog_or_tty->print_cr("Finished work stealing in %dth thread: %3.3f sec", | |
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3978 worker_id, _timer.seconds()); |
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3979 // XXX: need xxx/xxx type of notation, two timers |
0 | 3980 } |
3981 assert(_collector->_markStack.isEmpty(), "Should have been emptied"); | |
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3982 assert(work_queue(worker_id)->size() == 0, "Should have been emptied"); |
0 | 3983 // Note that under the current task protocol, the |
3984 // following assertion is true even of the spaces | |
3985 // expanded since the completion of the concurrent | |
3986 // marking. XXX This will likely change under a strict | |
3987 // ABORT semantics. | |
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3988 // After perm removal the comparison was changed to |
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3989 // greater than or equal to from strictly greater than. |
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3990 // Before perm removal the highest address sweep would |
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3991 // have been at the end of perm gen but now is at the |
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3992 // end of the tenured gen. |
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3993 assert(_global_finger >= _cms_space->end(), |
0 | 3994 "All tasks have been completed"); |
3995 DEBUG_ONLY(_collector->verify_overflow_empty();) | |
3996 } | |
3997 | |
3998 void CMSConcMarkingTask::bump_global_finger(HeapWord* f) { | |
3999 HeapWord* read = _global_finger; | |
4000 HeapWord* cur = read; | |
4001 while (f > read) { | |
4002 cur = read; | |
4003 read = (HeapWord*) Atomic::cmpxchg_ptr(f, &_global_finger, cur); | |
4004 if (cur == read) { | |
4005 // our cas succeeded | |
4006 assert(_global_finger >= f, "protocol consistency"); | |
4007 break; | |
4008 } | |
4009 } | |
4010 } | |
4011 | |
4012 // This is really inefficient, and should be redone by | |
4013 // using (not yet available) block-read and -write interfaces to the | |
4014 // stack and the work_queue. XXX FIX ME !!! | |
4015 bool CMSConcMarkingTask::get_work_from_overflow_stack(CMSMarkStack* ovflw_stk, | |
4016 OopTaskQueue* work_q) { | |
4017 // Fast lock-free check | |
4018 if (ovflw_stk->length() == 0) { | |
4019 return false; | |
4020 } | |
4021 assert(work_q->size() == 0, "Shouldn't steal"); | |
4022 MutexLockerEx ml(ovflw_stk->par_lock(), | |
4023 Mutex::_no_safepoint_check_flag); | |
4024 // Grab up to 1/4 the size of the work queue | |
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4025 size_t num = MIN2((size_t)(work_q->max_elems() - work_q->size())/4, |
0 | 4026 (size_t)ParGCDesiredObjsFromOverflowList); |
4027 num = MIN2(num, ovflw_stk->length()); | |
4028 for (int i = (int) num; i > 0; i--) { | |
4029 oop cur = ovflw_stk->pop(); | |
4030 assert(cur != NULL, "Counted wrong?"); | |
4031 work_q->push(cur); | |
4032 } | |
4033 return num > 0; | |
4034 } | |
4035 | |
4036 void CMSConcMarkingTask::do_scan_and_mark(int i, CompactibleFreeListSpace* sp) { | |
4037 SequentialSubTasksDone* pst = sp->conc_par_seq_tasks(); | |
4038 int n_tasks = pst->n_tasks(); | |
4039 // We allow that there may be no tasks to do here because | |
4040 // we are restarting after a stack overflow. | |
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4041 assert(pst->valid() || n_tasks == 0, "Uninitialized use?"); |
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4042 uint nth_task = 0; |
0 | 4043 |
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4044 HeapWord* aligned_start = sp->bottom(); |
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4045 if (sp->used_region().contains(_restart_addr)) { |
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4046 // Align down to a card boundary for the start of 0th task |
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4047 // for this space. |
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4048 aligned_start = |
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4049 (HeapWord*)align_size_down((uintptr_t)_restart_addr, |
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4050 CardTableModRefBS::card_size); |
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4051 } |
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4052 |
0 | 4053 size_t chunk_size = sp->marking_task_size(); |
4054 while (!pst->is_task_claimed(/* reference */ nth_task)) { | |
4055 // Having claimed the nth task in this space, | |
4056 // compute the chunk that it corresponds to: | |
340
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4057 MemRegion span = MemRegion(aligned_start + nth_task*chunk_size, |
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4058 aligned_start + (nth_task+1)*chunk_size); |
0 | 4059 // Try and bump the global finger via a CAS; |
4060 // note that we need to do the global finger bump | |
4061 // _before_ taking the intersection below, because | |
4062 // the task corresponding to that region will be | |
4063 // deemed done even if the used_region() expands | |
4064 // because of allocation -- as it almost certainly will | |
4065 // during start-up while the threads yield in the | |
4066 // closure below. | |
4067 HeapWord* finger = span.end(); | |
4068 bump_global_finger(finger); // atomically | |
4069 // There are null tasks here corresponding to chunks | |
4070 // beyond the "top" address of the space. | |
4071 span = span.intersection(sp->used_region()); | |
4072 if (!span.is_empty()) { // Non-null task | |
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4073 HeapWord* prev_obj; |
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4074 assert(!span.contains(_restart_addr) || nth_task == 0, |
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4075 "Inconsistency"); |
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4076 if (nth_task == 0) { |
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4077 // For the 0th task, we'll not need to compute a block_start. |
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4078 if (span.contains(_restart_addr)) { |
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4079 // In the case of a restart because of stack overflow, |
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4080 // we might additionally skip a chunk prefix. |
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4081 prev_obj = _restart_addr; |
0 | 4082 } else { |
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4083 prev_obj = span.start(); |
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4084 } |
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4085 } else { |
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4086 // We want to skip the first object because |
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4087 // the protocol is to scan any object in its entirety |
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4088 // that _starts_ in this span; a fortiori, any |
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4089 // object starting in an earlier span is scanned |
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4090 // as part of an earlier claimed task. |
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4091 // Below we use the "careful" version of block_start |
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4092 // so we do not try to navigate uninitialized objects. |
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4093 prev_obj = sp->block_start_careful(span.start()); |
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4094 // Below we use a variant of block_size that uses the |
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4095 // Printezis bits to avoid waiting for allocated |
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4096 // objects to become initialized/parsable. |
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4097 while (prev_obj < span.start()) { |
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4098 size_t sz = sp->block_size_no_stall(prev_obj, _collector); |
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4099 if (sz > 0) { |
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4100 prev_obj += sz; |
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4101 } else { |
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4102 // In this case we may end up doing a bit of redundant |
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4103 // scanning, but that appears unavoidable, short of |
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4104 // locking the free list locks; see bug 6324141. |
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4105 break; |
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4106 } |
0 | 4107 } |
4108 } | |
4109 if (prev_obj < span.end()) { | |
4110 MemRegion my_span = MemRegion(prev_obj, span.end()); | |
4111 // Do the marking work within a non-empty span -- | |
4112 // the last argument to the constructor indicates whether the | |
4113 // iteration should be incremental with periodic yields. | |
4114 Par_MarkFromRootsClosure cl(this, _collector, my_span, | |
4115 &_collector->_markBitMap, | |
4116 work_queue(i), | |
4117 &_collector->_markStack, | |
4118 _asynch); | |
4119 _collector->_markBitMap.iterate(&cl, my_span.start(), my_span.end()); | |
4120 } // else nothing to do for this task | |
4121 } // else nothing to do for this task | |
4122 } | |
4123 // We'd be tempted to assert here that since there are no | |
4124 // more tasks left to claim in this space, the global_finger | |
4125 // must exceed space->top() and a fortiori space->end(). However, | |
4126 // that would not quite be correct because the bumping of | |
4127 // global_finger occurs strictly after the claiming of a task, | |
4128 // so by the time we reach here the global finger may not yet | |
4129 // have been bumped up by the thread that claimed the last | |
4130 // task. | |
4131 pst->all_tasks_completed(); | |
4132 } | |
4133 | |
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4134 class Par_ConcMarkingClosure: public CMSOopClosure { |
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4135 private: |
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4136 CMSCollector* _collector; |
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4137 CMSConcMarkingTask* _task; |
0 | 4138 MemRegion _span; |
4139 CMSBitMap* _bit_map; | |
4140 CMSMarkStack* _overflow_stack; | |
4141 OopTaskQueue* _work_queue; | |
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4142 protected: |
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4143 DO_OOP_WORK_DEFN |
0 | 4144 public: |
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4145 Par_ConcMarkingClosure(CMSCollector* collector, CMSConcMarkingTask* task, OopTaskQueue* work_queue, |
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4146 CMSBitMap* bit_map, CMSMarkStack* overflow_stack): |
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4147 CMSOopClosure(collector->ref_processor()), |
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4148 _collector(collector), |
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4149 _task(task), |
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4150 _span(collector->_span), |
0 | 4151 _work_queue(work_queue), |
4152 _bit_map(bit_map), | |
935 | 4153 _overflow_stack(overflow_stack) |
4154 { } | |
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4155 virtual void do_oop(oop* p); |
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4156 virtual void do_oop(narrowOop* p); |
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4157 |
0 | 4158 void trim_queue(size_t max); |
4159 void handle_stack_overflow(HeapWord* lost); | |
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4160 void do_yield_check() { |
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4161 if (_task->should_yield()) { |
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4162 _task->yield(); |
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4163 } |
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4164 } |
0 | 4165 }; |
4166 | |
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4167 // Grey object scanning during work stealing phase -- |
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4168 // the salient assumption here is that any references |
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4169 // that are in these stolen objects being scanned must |
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4170 // already have been initialized (else they would not have |
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4171 // been published), so we do not need to check for |
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4172 // uninitialized objects before pushing here. |
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4173 void Par_ConcMarkingClosure::do_oop(oop obj) { |
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4174 assert(obj->is_oop_or_null(true), "expected an oop or NULL"); |
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4175 HeapWord* addr = (HeapWord*)obj; |
0 | 4176 // Check if oop points into the CMS generation |
4177 // and is not marked | |
4178 if (_span.contains(addr) && !_bit_map->isMarked(addr)) { | |
4179 // a white object ... | |
4180 // If we manage to "claim" the object, by being the | |
4181 // first thread to mark it, then we push it on our | |
4182 // marking stack | |
4183 if (_bit_map->par_mark(addr)) { // ... now grey | |
4184 // push on work queue (grey set) | |
4185 bool simulate_overflow = false; | |
4186 NOT_PRODUCT( | |
4187 if (CMSMarkStackOverflowALot && | |
4188 _collector->simulate_overflow()) { | |
4189 // simulate a stack overflow | |
4190 simulate_overflow = true; | |
4191 } | |
4192 ) | |
4193 if (simulate_overflow || | |
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4194 !(_work_queue->push(obj) || _overflow_stack->par_push(obj))) { |
0 | 4195 // stack overflow |
4196 if (PrintCMSStatistics != 0) { | |
4197 gclog_or_tty->print_cr("CMS marking stack overflow (benign) at " | |
4198 SIZE_FORMAT, _overflow_stack->capacity()); | |
4199 } | |
4200 // We cannot assert that the overflow stack is full because | |
4201 // it may have been emptied since. | |
4202 assert(simulate_overflow || | |
4203 _work_queue->size() == _work_queue->max_elems(), | |
4204 "Else push should have succeeded"); | |
4205 handle_stack_overflow(addr); | |
4206 } | |
4207 } // Else, some other thread got there first | |
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4208 do_yield_check(); |
0 | 4209 } |
4210 } | |
4211 | |
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4212 void Par_ConcMarkingClosure::do_oop(oop* p) { Par_ConcMarkingClosure::do_oop_work(p); } |
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4213 void Par_ConcMarkingClosure::do_oop(narrowOop* p) { Par_ConcMarkingClosure::do_oop_work(p); } |
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4214 |
0 | 4215 void Par_ConcMarkingClosure::trim_queue(size_t max) { |
4216 while (_work_queue->size() > max) { | |
4217 oop new_oop; | |
4218 if (_work_queue->pop_local(new_oop)) { | |
4219 assert(new_oop->is_oop(), "Should be an oop"); | |
4220 assert(_bit_map->isMarked((HeapWord*)new_oop), "Grey object"); | |
4221 assert(_span.contains((HeapWord*)new_oop), "Not in span"); | |
4222 new_oop->oop_iterate(this); // do_oop() above | |
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4223 do_yield_check(); |
0 | 4224 } |
4225 } | |
4226 } | |
4227 | |
4228 // Upon stack overflow, we discard (part of) the stack, | |
4229 // remembering the least address amongst those discarded | |
4230 // in CMSCollector's _restart_address. | |
4231 void Par_ConcMarkingClosure::handle_stack_overflow(HeapWord* lost) { | |
4232 // We need to do this under a mutex to prevent other | |
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4233 // workers from interfering with the work done below. |
0 | 4234 MutexLockerEx ml(_overflow_stack->par_lock(), |
4235 Mutex::_no_safepoint_check_flag); | |
4236 // Remember the least grey address discarded | |
4237 HeapWord* ra = (HeapWord*)_overflow_stack->least_value(lost); | |
4238 _collector->lower_restart_addr(ra); | |
4239 _overflow_stack->reset(); // discard stack contents | |
4240 _overflow_stack->expand(); // expand the stack if possible | |
4241 } | |
4242 | |
4243 | |
4244 void CMSConcMarkingTask::do_work_steal(int i) { | |
4245 OopTaskQueue* work_q = work_queue(i); | |
4246 oop obj_to_scan; | |
4247 CMSBitMap* bm = &(_collector->_markBitMap); | |
4248 CMSMarkStack* ovflw = &(_collector->_markStack); | |
4249 int* seed = _collector->hash_seed(i); | |
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4250 Par_ConcMarkingClosure cl(_collector, this, work_q, bm, ovflw); |
0 | 4251 while (true) { |
4252 cl.trim_queue(0); | |
4253 assert(work_q->size() == 0, "Should have been emptied above"); | |
4254 if (get_work_from_overflow_stack(ovflw, work_q)) { | |
4255 // Can't assert below because the work obtained from the | |
4256 // overflow stack may already have been stolen from us. | |
4257 // assert(work_q->size() > 0, "Work from overflow stack"); | |
4258 continue; | |
4259 } else if (task_queues()->steal(i, seed, /* reference */ obj_to_scan)) { | |
4260 assert(obj_to_scan->is_oop(), "Should be an oop"); | |
4261 assert(bm->isMarked((HeapWord*)obj_to_scan), "Grey object"); | |
4262 obj_to_scan->oop_iterate(&cl); | |
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4263 } else if (terminator()->offer_termination(&_term_term)) { |
0 | 4264 assert(work_q->size() == 0, "Impossible!"); |
4265 break; | |
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4266 } else if (yielding() || should_yield()) { |
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4267 yield(); |
0 | 4268 } |
4269 } | |
4270 } | |
4271 | |
4272 // This is run by the CMS (coordinator) thread. | |
4273 void CMSConcMarkingTask::coordinator_yield() { | |
4274 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
4275 "CMS thread should hold CMS token"); | |
4276 // First give up the locks, then yield, then re-lock | |
4277 // We should probably use a constructor/destructor idiom to | |
4278 // do this unlock/lock or modify the MutexUnlocker class to | |
4279 // serve our purpose. XXX | |
4280 assert_lock_strong(_bit_map_lock); | |
4281 _bit_map_lock->unlock(); | |
4282 ConcurrentMarkSweepThread::desynchronize(true); | |
4283 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
4284 _collector->stopTimer(); | |
4285 if (PrintCMSStatistics != 0) { | |
4286 _collector->incrementYields(); | |
4287 } | |
4288 _collector->icms_wait(); | |
4289 | |
4290 // It is possible for whichever thread initiated the yield request | |
4291 // not to get a chance to wake up and take the bitmap lock between | |
4292 // this thread releasing it and reacquiring it. So, while the | |
4293 // should_yield() flag is on, let's sleep for a bit to give the | |
4294 // other thread a chance to wake up. The limit imposed on the number | |
4295 // of iterations is defensive, to avoid any unforseen circumstances | |
4296 // putting us into an infinite loop. Since it's always been this | |
4297 // (coordinator_yield()) method that was observed to cause the | |
4298 // problem, we are using a parameter (CMSCoordinatorYieldSleepCount) | |
4299 // which is by default non-zero. For the other seven methods that | |
4300 // also perform the yield operation, as are using a different | |
4301 // parameter (CMSYieldSleepCount) which is by default zero. This way we | |
4302 // can enable the sleeping for those methods too, if necessary. | |
4303 // See 6442774. | |
4304 // | |
4305 // We really need to reconsider the synchronization between the GC | |
4306 // thread and the yield-requesting threads in the future and we | |
4307 // should really use wait/notify, which is the recommended | |
4308 // way of doing this type of interaction. Additionally, we should | |
4309 // consolidate the eight methods that do the yield operation and they | |
4310 // are almost identical into one for better maintenability and | |
4311 // readability. See 6445193. | |
4312 // | |
4313 // Tony 2006.06.29 | |
4314 for (unsigned i = 0; i < CMSCoordinatorYieldSleepCount && | |
113
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4315 ConcurrentMarkSweepThread::should_yield() && |
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4316 !CMSCollector::foregroundGCIsActive(); ++i) { |
0 | 4317 os::sleep(Thread::current(), 1, false); |
4318 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
4319 } | |
4320 | |
4321 ConcurrentMarkSweepThread::synchronize(true); | |
4322 _bit_map_lock->lock_without_safepoint_check(); | |
4323 _collector->startTimer(); | |
4324 } | |
4325 | |
4326 bool CMSCollector::do_marking_mt(bool asynch) { | |
1284 | 4327 assert(ConcGCThreads > 0 && conc_workers() != NULL, "precondition"); |
4095
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4328 int num_workers = AdaptiveSizePolicy::calc_active_conc_workers( |
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4329 conc_workers()->total_workers(), |
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4330 conc_workers()->active_workers(), |
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4331 Threads::number_of_non_daemon_threads()); |
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4332 conc_workers()->set_active_workers(num_workers); |
0 | 4333 |
4334 CompactibleFreeListSpace* cms_space = _cmsGen->cmsSpace(); | |
4335 | |
1833
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4336 CMSConcMarkingTask tsk(this, |
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4337 cms_space, |
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4338 asynch, |
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4339 conc_workers(), |
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4340 task_queues()); |
0 | 4341 |
4342 // Since the actual number of workers we get may be different | |
4343 // from the number we requested above, do we need to do anything different | |
4344 // below? In particular, may be we need to subclass the SequantialSubTasksDone | |
4345 // class?? XXX | |
4346 cms_space ->initialize_sequential_subtasks_for_marking(num_workers); | |
4347 | |
4348 // Refs discovery is already non-atomic. | |
4349 assert(!ref_processor()->discovery_is_atomic(), "Should be non-atomic"); | |
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4350 assert(ref_processor()->discovery_is_mt(), "Discovery should be MT"); |
0 | 4351 conc_workers()->start_task(&tsk); |
4352 while (tsk.yielded()) { | |
4353 tsk.coordinator_yield(); | |
4354 conc_workers()->continue_task(&tsk); | |
4355 } | |
4356 // If the task was aborted, _restart_addr will be non-NULL | |
4357 assert(tsk.completed() || _restart_addr != NULL, "Inconsistency"); | |
4358 while (_restart_addr != NULL) { | |
4359 // XXX For now we do not make use of ABORTED state and have not | |
4360 // yet implemented the right abort semantics (even in the original | |
4361 // single-threaded CMS case). That needs some more investigation | |
4362 // and is deferred for now; see CR# TBF. 07252005YSR. XXX | |
4363 assert(!CMSAbortSemantics || tsk.aborted(), "Inconsistency"); | |
4364 // If _restart_addr is non-NULL, a marking stack overflow | |
605 | 4365 // occurred; we need to do a fresh marking iteration from the |
0 | 4366 // indicated restart address. |
4367 if (_foregroundGCIsActive && asynch) { | |
4368 // We may be running into repeated stack overflows, having | |
4369 // reached the limit of the stack size, while making very | |
4370 // slow forward progress. It may be best to bail out and | |
4371 // let the foreground collector do its job. | |
4372 // Clear _restart_addr, so that foreground GC | |
4373 // works from scratch. This avoids the headache of | |
4374 // a "rescan" which would otherwise be needed because | |
4375 // of the dirty mod union table & card table. | |
4376 _restart_addr = NULL; | |
4377 return false; | |
4378 } | |
4379 // Adjust the task to restart from _restart_addr | |
4380 tsk.reset(_restart_addr); | |
4381 cms_space ->initialize_sequential_subtasks_for_marking(num_workers, | |
4382 _restart_addr); | |
4383 _restart_addr = NULL; | |
4384 // Get the workers going again | |
4385 conc_workers()->start_task(&tsk); | |
4386 while (tsk.yielded()) { | |
4387 tsk.coordinator_yield(); | |
4388 conc_workers()->continue_task(&tsk); | |
4389 } | |
4390 } | |
4391 assert(tsk.completed(), "Inconsistency"); | |
4392 assert(tsk.result() == true, "Inconsistency"); | |
4393 return true; | |
4394 } | |
4395 | |
4396 bool CMSCollector::do_marking_st(bool asynch) { | |
4397 ResourceMark rm; | |
4398 HandleMark hm; | |
4399 | |
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4400 // Temporarily make refs discovery single threaded (non-MT) |
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4401 ReferenceProcessorMTDiscoveryMutator rp_mut_discovery(ref_processor(), false); |
0 | 4402 MarkFromRootsClosure markFromRootsClosure(this, _span, &_markBitMap, |
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4403 &_markStack, CMSYield && asynch); |
0 | 4404 // the last argument to iterate indicates whether the iteration |
4405 // should be incremental with periodic yields. | |
4406 _markBitMap.iterate(&markFromRootsClosure); | |
4407 // If _restart_addr is non-NULL, a marking stack overflow | |
605 | 4408 // occurred; we need to do a fresh iteration from the |
0 | 4409 // indicated restart address. |
4410 while (_restart_addr != NULL) { | |
4411 if (_foregroundGCIsActive && asynch) { | |
4412 // We may be running into repeated stack overflows, having | |
4413 // reached the limit of the stack size, while making very | |
4414 // slow forward progress. It may be best to bail out and | |
4415 // let the foreground collector do its job. | |
4416 // Clear _restart_addr, so that foreground GC | |
4417 // works from scratch. This avoids the headache of | |
4418 // a "rescan" which would otherwise be needed because | |
4419 // of the dirty mod union table & card table. | |
4420 _restart_addr = NULL; | |
4421 return false; // indicating failure to complete marking | |
4422 } | |
4423 // Deal with stack overflow: | |
4424 // we restart marking from _restart_addr | |
4425 HeapWord* ra = _restart_addr; | |
4426 markFromRootsClosure.reset(ra); | |
4427 _restart_addr = NULL; | |
4428 _markBitMap.iterate(&markFromRootsClosure, ra, _span.end()); | |
4429 } | |
4430 return true; | |
4431 } | |
4432 | |
4433 void CMSCollector::preclean() { | |
4434 check_correct_thread_executing(); | |
4435 assert(Thread::current()->is_ConcurrentGC_thread(), "Wrong thread"); | |
4436 verify_work_stacks_empty(); | |
4437 verify_overflow_empty(); | |
4438 _abort_preclean = false; | |
4439 if (CMSPrecleaningEnabled) { | |
4440 _eden_chunk_index = 0; | |
4441 size_t used = get_eden_used(); | |
4442 size_t capacity = get_eden_capacity(); | |
4443 // Don't start sampling unless we will get sufficiently | |
4444 // many samples. | |
4445 if (used < (capacity/(CMSScheduleRemarkSamplingRatio * 100) | |
4446 * CMSScheduleRemarkEdenPenetration)) { | |
4447 _start_sampling = true; | |
4448 } else { | |
4449 _start_sampling = false; | |
4450 } | |
4451 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
4452 CMSPhaseAccounting pa(this, "preclean", !PrintGCDetails); | |
4453 preclean_work(CMSPrecleanRefLists1, CMSPrecleanSurvivors1); | |
4454 } | |
4455 CMSTokenSync x(true); // is cms thread | |
4456 if (CMSPrecleaningEnabled) { | |
4457 sample_eden(); | |
4458 _collectorState = AbortablePreclean; | |
4459 } else { | |
4460 _collectorState = FinalMarking; | |
4461 } | |
4462 verify_work_stacks_empty(); | |
4463 verify_overflow_empty(); | |
4464 } | |
4465 | |
4466 // Try and schedule the remark such that young gen | |
4467 // occupancy is CMSScheduleRemarkEdenPenetration %. | |
4468 void CMSCollector::abortable_preclean() { | |
4469 check_correct_thread_executing(); | |
4470 assert(CMSPrecleaningEnabled, "Inconsistent control state"); | |
4471 assert(_collectorState == AbortablePreclean, "Inconsistent control state"); | |
4472 | |
4473 // If Eden's current occupancy is below this threshold, | |
4474 // immediately schedule the remark; else preclean | |
4475 // past the next scavenge in an effort to | |
4476 // schedule the pause as described avove. By choosing | |
4477 // CMSScheduleRemarkEdenSizeThreshold >= max eden size | |
4478 // we will never do an actual abortable preclean cycle. | |
4479 if (get_eden_used() > CMSScheduleRemarkEdenSizeThreshold) { | |
4480 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
4481 CMSPhaseAccounting pa(this, "abortable-preclean", !PrintGCDetails); | |
4482 // We need more smarts in the abortable preclean | |
4483 // loop below to deal with cases where allocation | |
4484 // in young gen is very very slow, and our precleaning | |
4485 // is running a losing race against a horde of | |
4486 // mutators intent on flooding us with CMS updates | |
4487 // (dirty cards). | |
4488 // One, admittedly dumb, strategy is to give up | |
4489 // after a certain number of abortable precleaning loops | |
4490 // or after a certain maximum time. We want to make | |
4491 // this smarter in the next iteration. | |
4492 // XXX FIX ME!!! YSR | |
4493 size_t loops = 0, workdone = 0, cumworkdone = 0, waited = 0; | |
4494 while (!(should_abort_preclean() || | |
4495 ConcurrentMarkSweepThread::should_terminate())) { | |
4496 workdone = preclean_work(CMSPrecleanRefLists2, CMSPrecleanSurvivors2); | |
4497 cumworkdone += workdone; | |
4498 loops++; | |
4499 // Voluntarily terminate abortable preclean phase if we have | |
4500 // been at it for too long. | |
4501 if ((CMSMaxAbortablePrecleanLoops != 0) && | |
4502 loops >= CMSMaxAbortablePrecleanLoops) { | |
4503 if (PrintGCDetails) { | |
4504 gclog_or_tty->print(" CMS: abort preclean due to loops "); | |
4505 } | |
4506 break; | |
4507 } | |
4508 if (pa.wallclock_millis() > CMSMaxAbortablePrecleanTime) { | |
4509 if (PrintGCDetails) { | |
4510 gclog_or_tty->print(" CMS: abort preclean due to time "); | |
4511 } | |
4512 break; | |
4513 } | |
4514 // If we are doing little work each iteration, we should | |
4515 // take a short break. | |
4516 if (workdone < CMSAbortablePrecleanMinWorkPerIteration) { | |
4517 // Sleep for some time, waiting for work to accumulate | |
4518 stopTimer(); | |
4519 cmsThread()->wait_on_cms_lock(CMSAbortablePrecleanWaitMillis); | |
4520 startTimer(); | |
4521 waited++; | |
4522 } | |
4523 } | |
4524 if (PrintCMSStatistics > 0) { | |
4525 gclog_or_tty->print(" [%d iterations, %d waits, %d cards)] ", | |
4526 loops, waited, cumworkdone); | |
4527 } | |
4528 } | |
4529 CMSTokenSync x(true); // is cms thread | |
4530 if (_collectorState != Idling) { | |
4531 assert(_collectorState == AbortablePreclean, | |
4532 "Spontaneous state transition?"); | |
4533 _collectorState = FinalMarking; | |
4534 } // Else, a foreground collection completed this CMS cycle. | |
4535 return; | |
4536 } | |
4537 | |
4538 // Respond to an Eden sampling opportunity | |
4539 void CMSCollector::sample_eden() { | |
4540 // Make sure a young gc cannot sneak in between our | |
4541 // reading and recording of a sample. | |
4542 assert(Thread::current()->is_ConcurrentGC_thread(), | |
4543 "Only the cms thread may collect Eden samples"); | |
4544 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
4545 "Should collect samples while holding CMS token"); | |
4546 if (!_start_sampling) { | |
4547 return; | |
4548 } | |
4549 if (_eden_chunk_array) { | |
4550 if (_eden_chunk_index < _eden_chunk_capacity) { | |
4551 _eden_chunk_array[_eden_chunk_index] = *_top_addr; // take sample | |
4552 assert(_eden_chunk_array[_eden_chunk_index] <= *_end_addr, | |
4553 "Unexpected state of Eden"); | |
4554 // We'd like to check that what we just sampled is an oop-start address; | |
4555 // however, we cannot do that here since the object may not yet have been | |
4556 // initialized. So we'll instead do the check when we _use_ this sample | |
4557 // later. | |
4558 if (_eden_chunk_index == 0 || | |
4559 (pointer_delta(_eden_chunk_array[_eden_chunk_index], | |
4560 _eden_chunk_array[_eden_chunk_index-1]) | |
4561 >= CMSSamplingGrain)) { | |
4562 _eden_chunk_index++; // commit sample | |
4563 } | |
4564 } | |
4565 } | |
4566 if ((_collectorState == AbortablePreclean) && !_abort_preclean) { | |
4567 size_t used = get_eden_used(); | |
4568 size_t capacity = get_eden_capacity(); | |
4569 assert(used <= capacity, "Unexpected state of Eden"); | |
4570 if (used > (capacity/100 * CMSScheduleRemarkEdenPenetration)) { | |
4571 _abort_preclean = true; | |
4572 } | |
4573 } | |
4574 } | |
4575 | |
4576 | |
4577 size_t CMSCollector::preclean_work(bool clean_refs, bool clean_survivor) { | |
4578 assert(_collectorState == Precleaning || | |
4579 _collectorState == AbortablePreclean, "incorrect state"); | |
4580 ResourceMark rm; | |
4581 HandleMark hm; | |
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4582 |
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4583 // Precleaning is currently not MT but the reference processor |
92da084fefc9
6668573: CMS: reference processing crash if ParallelCMSThreads > ParallelGCThreads
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4584 // may be set for MT. Disable it temporarily here. |
92da084fefc9
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4585 ReferenceProcessor* rp = ref_processor(); |
92da084fefc9
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4586 ReferenceProcessorMTDiscoveryMutator rp_mut_discovery(rp, false); |
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|
4587 |
0 | 4588 // Do one pass of scrubbing the discovered reference lists |
4589 // to remove any reference objects with strongly-reachable | |
4590 // referents. | |
4591 if (clean_refs) { | |
4592 CMSPrecleanRefsYieldClosure yield_cl(this); | |
4593 assert(rp->span().equals(_span), "Spans should be equal"); | |
4594 CMSKeepAliveClosure keep_alive(this, _span, &_markBitMap, | |
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4595 &_markStack, true /* preclean */); |
0 | 4596 CMSDrainMarkingStackClosure complete_trace(this, |
452
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360
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4597 _span, &_markBitMap, &_markStack, |
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4598 &keep_alive, true /* preclean */); |
0 | 4599 |
4600 // We don't want this step to interfere with a young | |
4601 // collection because we don't want to take CPU | |
4602 // or memory bandwidth away from the young GC threads | |
4603 // (which may be as many as there are CPUs). | |
4604 // Note that we don't need to protect ourselves from | |
4605 // interference with mutators because they can't | |
4606 // manipulate the discovered reference lists nor affect | |
4607 // the computed reachability of the referents, the | |
4608 // only properties manipulated by the precleaning | |
4609 // of these reference lists. | |
4610 stopTimer(); | |
4611 CMSTokenSyncWithLocks x(true /* is cms thread */, | |
4612 bitMapLock()); | |
4613 startTimer(); | |
4614 sample_eden(); | |
935 | 4615 |
0 | 4616 // The following will yield to allow foreground |
4617 // collection to proceed promptly. XXX YSR: | |
4618 // The code in this method may need further | |
4619 // tweaking for better performance and some restructuring | |
4620 // for cleaner interfaces. | |
10405 | 4621 GCTimer *gc_timer = NULL; // Currently not tracing concurrent phases |
0 | 4622 rp->preclean_discovered_references( |
10405 | 4623 rp->is_alive_non_header(), &keep_alive, &complete_trace, &yield_cl, |
4624 gc_timer); | |
0 | 4625 } |
4626 | |
4627 if (clean_survivor) { // preclean the active survivor space(s) | |
4628 assert(_young_gen->kind() == Generation::DefNew || | |
4629 _young_gen->kind() == Generation::ParNew || | |
4630 _young_gen->kind() == Generation::ASParNew, | |
4631 "incorrect type for cast"); | |
4632 DefNewGeneration* dng = (DefNewGeneration*)_young_gen; | |
4633 PushAndMarkClosure pam_cl(this, _span, ref_processor(), | |
4634 &_markBitMap, &_modUnionTable, | |
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4635 &_markStack, true /* precleaning phase */); |
0 | 4636 stopTimer(); |
4637 CMSTokenSyncWithLocks ts(true /* is cms thread */, | |
4638 bitMapLock()); | |
4639 startTimer(); | |
4640 unsigned int before_count = | |
4641 GenCollectedHeap::heap()->total_collections(); | |
4642 SurvivorSpacePrecleanClosure | |
4643 sss_cl(this, _span, &_markBitMap, &_markStack, | |
4644 &pam_cl, before_count, CMSYield); | |
4645 dng->from()->object_iterate_careful(&sss_cl); | |
4646 dng->to()->object_iterate_careful(&sss_cl); | |
4647 } | |
4648 MarkRefsIntoAndScanClosure | |
4649 mrias_cl(_span, ref_processor(), &_markBitMap, &_modUnionTable, | |
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4650 &_markStack, this, CMSYield, |
0 | 4651 true /* precleaning phase */); |
4652 // CAUTION: The following closure has persistent state that may need to | |
4653 // be reset upon a decrease in the sequence of addresses it | |
4654 // processes. | |
4655 ScanMarkedObjectsAgainCarefullyClosure | |
4656 smoac_cl(this, _span, | |
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4657 &_markBitMap, &_markStack, &mrias_cl, CMSYield); |
0 | 4658 |
4659 // Preclean dirty cards in ModUnionTable and CardTable using | |
4660 // appropriate convergence criterion; | |
4661 // repeat CMSPrecleanIter times unless we find that | |
4662 // we are losing. | |
4663 assert(CMSPrecleanIter < 10, "CMSPrecleanIter is too large"); | |
4664 assert(CMSPrecleanNumerator < CMSPrecleanDenominator, | |
4665 "Bad convergence multiplier"); | |
4666 assert(CMSPrecleanThreshold >= 100, | |
4667 "Unreasonably low CMSPrecleanThreshold"); | |
4668 | |
4669 size_t numIter, cumNumCards, lastNumCards, curNumCards; | |
4670 for (numIter = 0, cumNumCards = lastNumCards = curNumCards = 0; | |
4671 numIter < CMSPrecleanIter; | |
4672 numIter++, lastNumCards = curNumCards, cumNumCards += curNumCards) { | |
4673 curNumCards = preclean_mod_union_table(_cmsGen, &smoac_cl); | |
4674 if (Verbose && PrintGCDetails) { | |
4675 gclog_or_tty->print(" (modUnionTable: %d cards)", curNumCards); | |
4676 } | |
4677 // Either there are very few dirty cards, so re-mark | |
4678 // pause will be small anyway, or our pre-cleaning isn't | |
4679 // that much faster than the rate at which cards are being | |
4680 // dirtied, so we might as well stop and re-mark since | |
4681 // precleaning won't improve our re-mark time by much. | |
4682 if (curNumCards <= CMSPrecleanThreshold || | |
4683 (numIter > 0 && | |
4684 (curNumCards * CMSPrecleanDenominator > | |
4685 lastNumCards * CMSPrecleanNumerator))) { | |
4686 numIter++; | |
4687 cumNumCards += curNumCards; | |
4688 break; | |
4689 } | |
4690 } | |
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4691 |
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4692 preclean_klasses(&mrias_cl, _cmsGen->freelistLock()); |
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4693 |
0 | 4694 curNumCards = preclean_card_table(_cmsGen, &smoac_cl); |
4695 cumNumCards += curNumCards; | |
4696 if (PrintGCDetails && PrintCMSStatistics != 0) { | |
4697 gclog_or_tty->print_cr(" (cardTable: %d cards, re-scanned %d cards, %d iterations)", | |
4698 curNumCards, cumNumCards, numIter); | |
4699 } | |
4700 return cumNumCards; // as a measure of useful work done | |
4701 } | |
4702 | |
4703 // PRECLEANING NOTES: | |
4704 // Precleaning involves: | |
4705 // . reading the bits of the modUnionTable and clearing the set bits. | |
4706 // . For the cards corresponding to the set bits, we scan the | |
4707 // objects on those cards. This means we need the free_list_lock | |
4708 // so that we can safely iterate over the CMS space when scanning | |
4709 // for oops. | |
4710 // . When we scan the objects, we'll be both reading and setting | |
4711 // marks in the marking bit map, so we'll need the marking bit map. | |
4712 // . For protecting _collector_state transitions, we take the CGC_lock. | |
4713 // Note that any races in the reading of of card table entries by the | |
4714 // CMS thread on the one hand and the clearing of those entries by the | |
4715 // VM thread or the setting of those entries by the mutator threads on the | |
4716 // other are quite benign. However, for efficiency it makes sense to keep | |
4717 // the VM thread from racing with the CMS thread while the latter is | |
4718 // dirty card info to the modUnionTable. We therefore also use the | |
4719 // CGC_lock to protect the reading of the card table and the mod union | |
4720 // table by the CM thread. | |
4721 // . We run concurrently with mutator updates, so scanning | |
4722 // needs to be done carefully -- we should not try to scan | |
4723 // potentially uninitialized objects. | |
4724 // | |
4725 // Locking strategy: While holding the CGC_lock, we scan over and | |
4726 // reset a maximal dirty range of the mod union / card tables, then lock | |
4727 // the free_list_lock and bitmap lock to do a full marking, then | |
4728 // release these locks; and repeat the cycle. This allows for a | |
4729 // certain amount of fairness in the sharing of these locks between | |
4730 // the CMS collector on the one hand, and the VM thread and the | |
4731 // mutators on the other. | |
4732 | |
4733 // NOTE: preclean_mod_union_table() and preclean_card_table() | |
4734 // further below are largely identical; if you need to modify | |
4735 // one of these methods, please check the other method too. | |
4736 | |
4737 size_t CMSCollector::preclean_mod_union_table( | |
4738 ConcurrentMarkSweepGeneration* gen, | |
4739 ScanMarkedObjectsAgainCarefullyClosure* cl) { | |
4740 verify_work_stacks_empty(); | |
4741 verify_overflow_empty(); | |
4742 | |
4743 // strategy: starting with the first card, accumulate contiguous | |
4744 // ranges of dirty cards; clear these cards, then scan the region | |
4745 // covered by these cards. | |
4746 | |
4747 // Since all of the MUT is committed ahead, we can just use | |
4748 // that, in case the generations expand while we are precleaning. | |
4749 // It might also be fine to just use the committed part of the | |
4750 // generation, but we might potentially miss cards when the | |
4751 // generation is rapidly expanding while we are in the midst | |
4752 // of precleaning. | |
4753 HeapWord* startAddr = gen->reserved().start(); | |
4754 HeapWord* endAddr = gen->reserved().end(); | |
4755 | |
4756 cl->setFreelistLock(gen->freelistLock()); // needed for yielding | |
4757 | |
4758 size_t numDirtyCards, cumNumDirtyCards; | |
4759 HeapWord *nextAddr, *lastAddr; | |
4760 for (cumNumDirtyCards = numDirtyCards = 0, | |
4761 nextAddr = lastAddr = startAddr; | |
4762 nextAddr < endAddr; | |
4763 nextAddr = lastAddr, cumNumDirtyCards += numDirtyCards) { | |
4764 | |
4765 ResourceMark rm; | |
4766 HandleMark hm; | |
4767 | |
4768 MemRegion dirtyRegion; | |
4769 { | |
4770 stopTimer(); | |
935 | 4771 // Potential yield point |
0 | 4772 CMSTokenSync ts(true); |
4773 startTimer(); | |
4774 sample_eden(); | |
4775 // Get dirty region starting at nextOffset (inclusive), | |
4776 // simultaneously clearing it. | |
4777 dirtyRegion = | |
4778 _modUnionTable.getAndClearMarkedRegion(nextAddr, endAddr); | |
4779 assert(dirtyRegion.start() >= nextAddr, | |
4780 "returned region inconsistent?"); | |
4781 } | |
4782 // Remember where the next search should begin. | |
4783 // The returned region (if non-empty) is a right open interval, | |
4784 // so lastOffset is obtained from the right end of that | |
4785 // interval. | |
4786 lastAddr = dirtyRegion.end(); | |
4787 // Should do something more transparent and less hacky XXX | |
4788 numDirtyCards = | |
4789 _modUnionTable.heapWordDiffToOffsetDiff(dirtyRegion.word_size()); | |
4790 | |
4791 // We'll scan the cards in the dirty region (with periodic | |
4792 // yields for foreground GC as needed). | |
4793 if (!dirtyRegion.is_empty()) { | |
4794 assert(numDirtyCards > 0, "consistency check"); | |
4795 HeapWord* stop_point = NULL; | |
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4796 stopTimer(); |
935 | 4797 // Potential yield point |
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4798 CMSTokenSyncWithLocks ts(true, gen->freelistLock(), |
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4799 bitMapLock()); |
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4800 startTimer(); |
0 | 4801 { |
4802 verify_work_stacks_empty(); | |
4803 verify_overflow_empty(); | |
4804 sample_eden(); | |
4805 stop_point = | |
4806 gen->cmsSpace()->object_iterate_careful_m(dirtyRegion, cl); | |
4807 } | |
4808 if (stop_point != NULL) { | |
4809 // The careful iteration stopped early either because it found an | |
4810 // uninitialized object, or because we were in the midst of an | |
4811 // "abortable preclean", which should now be aborted. Redirty | |
4812 // the bits corresponding to the partially-scanned or unscanned | |
4813 // cards. We'll either restart at the next block boundary or | |
4814 // abort the preclean. | |
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4815 assert((_collectorState == AbortablePreclean && should_abort_preclean()), |
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4816 "Should only be AbortablePreclean."); |
0 | 4817 _modUnionTable.mark_range(MemRegion(stop_point, dirtyRegion.end())); |
4818 if (should_abort_preclean()) { | |
4819 break; // out of preclean loop | |
4820 } else { | |
4821 // Compute the next address at which preclean should pick up; | |
4822 // might need bitMapLock in order to read P-bits. | |
4823 lastAddr = next_card_start_after_block(stop_point); | |
4824 } | |
4825 } | |
4826 } else { | |
4827 assert(lastAddr == endAddr, "consistency check"); | |
4828 assert(numDirtyCards == 0, "consistency check"); | |
4829 break; | |
4830 } | |
4831 } | |
4832 verify_work_stacks_empty(); | |
4833 verify_overflow_empty(); | |
4834 return cumNumDirtyCards; | |
4835 } | |
4836 | |
4837 // NOTE: preclean_mod_union_table() above and preclean_card_table() | |
4838 // below are largely identical; if you need to modify | |
4839 // one of these methods, please check the other method too. | |
4840 | |
4841 size_t CMSCollector::preclean_card_table(ConcurrentMarkSweepGeneration* gen, | |
4842 ScanMarkedObjectsAgainCarefullyClosure* cl) { | |
4843 // strategy: it's similar to precleamModUnionTable above, in that | |
4844 // we accumulate contiguous ranges of dirty cards, mark these cards | |
4845 // precleaned, then scan the region covered by these cards. | |
4846 HeapWord* endAddr = (HeapWord*)(gen->_virtual_space.high()); | |
4847 HeapWord* startAddr = (HeapWord*)(gen->_virtual_space.low()); | |
4848 | |
4849 cl->setFreelistLock(gen->freelistLock()); // needed for yielding | |
4850 | |
4851 size_t numDirtyCards, cumNumDirtyCards; | |
4852 HeapWord *lastAddr, *nextAddr; | |
4853 | |
4854 for (cumNumDirtyCards = numDirtyCards = 0, | |
4855 nextAddr = lastAddr = startAddr; | |
4856 nextAddr < endAddr; | |
4857 nextAddr = lastAddr, cumNumDirtyCards += numDirtyCards) { | |
4858 | |
4859 ResourceMark rm; | |
4860 HandleMark hm; | |
4861 | |
4862 MemRegion dirtyRegion; | |
4863 { | |
4864 // See comments in "Precleaning notes" above on why we | |
4865 // do this locking. XXX Could the locking overheads be | |
4866 // too high when dirty cards are sparse? [I don't think so.] | |
4867 stopTimer(); | |
4868 CMSTokenSync x(true); // is cms thread | |
4869 startTimer(); | |
4870 sample_eden(); | |
4871 // Get and clear dirty region from card table | |
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4872 dirtyRegion = _ct->ct_bs()->dirty_card_range_after_reset( |
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4873 MemRegion(nextAddr, endAddr), |
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4874 true, |
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4875 CardTableModRefBS::precleaned_card_val()); |
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4876 |
0 | 4877 assert(dirtyRegion.start() >= nextAddr, |
4878 "returned region inconsistent?"); | |
4879 } | |
4880 lastAddr = dirtyRegion.end(); | |
4881 numDirtyCards = | |
4882 dirtyRegion.word_size()/CardTableModRefBS::card_size_in_words; | |
4883 | |
4884 if (!dirtyRegion.is_empty()) { | |
4885 stopTimer(); | |
4886 CMSTokenSyncWithLocks ts(true, gen->freelistLock(), bitMapLock()); | |
4887 startTimer(); | |
4888 sample_eden(); | |
4889 verify_work_stacks_empty(); | |
4890 verify_overflow_empty(); | |
4891 HeapWord* stop_point = | |
4892 gen->cmsSpace()->object_iterate_careful_m(dirtyRegion, cl); | |
4893 if (stop_point != NULL) { | |
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4894 assert((_collectorState == AbortablePreclean && should_abort_preclean()), |
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4895 "Should only be AbortablePreclean."); |
0 | 4896 _ct->ct_bs()->invalidate(MemRegion(stop_point, dirtyRegion.end())); |
4897 if (should_abort_preclean()) { | |
4898 break; // out of preclean loop | |
4899 } else { | |
4900 // Compute the next address at which preclean should pick up. | |
4901 lastAddr = next_card_start_after_block(stop_point); | |
4902 } | |
4903 } | |
4904 } else { | |
4905 break; | |
4906 } | |
4907 } | |
4908 verify_work_stacks_empty(); | |
4909 verify_overflow_empty(); | |
4910 return cumNumDirtyCards; | |
4911 } | |
4912 | |
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4913 class PrecleanKlassClosure : public KlassClosure { |
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4914 CMKlassClosure _cm_klass_closure; |
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4915 public: |
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4916 PrecleanKlassClosure(OopClosure* oop_closure) : _cm_klass_closure(oop_closure) {} |
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4917 void do_klass(Klass* k) { |
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4918 if (k->has_accumulated_modified_oops()) { |
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4919 k->clear_accumulated_modified_oops(); |
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4920 |
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4921 _cm_klass_closure.do_klass(k); |
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4922 } |
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4923 } |
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4924 }; |
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4925 |
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4926 // The freelist lock is needed to prevent asserts, is it really needed? |
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4927 void CMSCollector::preclean_klasses(MarkRefsIntoAndScanClosure* cl, Mutex* freelistLock) { |
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4928 |
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4929 cl->set_freelistLock(freelistLock); |
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4930 |
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4931 CMSTokenSyncWithLocks ts(true, freelistLock, bitMapLock()); |
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4932 |
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4933 // SSS: Add equivalent to ScanMarkedObjectsAgainCarefullyClosure::do_yield_check and should_abort_preclean? |
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4934 // SSS: We should probably check if precleaning should be aborted, at suitable intervals? |
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4935 PrecleanKlassClosure preclean_klass_closure(cl); |
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4936 ClassLoaderDataGraph::classes_do(&preclean_klass_closure); |
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4937 |
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4938 verify_work_stacks_empty(); |
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4939 verify_overflow_empty(); |
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4940 } |
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4941 |
0 | 4942 void CMSCollector::checkpointRootsFinal(bool asynch, |
4943 bool clear_all_soft_refs, bool init_mark_was_synchronous) { | |
4944 assert(_collectorState == FinalMarking, "incorrect state transition?"); | |
4945 check_correct_thread_executing(); | |
4946 // world is stopped at this checkpoint | |
4947 assert(SafepointSynchronize::is_at_safepoint(), | |
4948 "world should be stopped"); | |
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4949 TraceCMSMemoryManagerStats tms(_collectorState,GenCollectedHeap::heap()->gc_cause()); |
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4950 |
0 | 4951 verify_work_stacks_empty(); |
4952 verify_overflow_empty(); | |
4953 | |
4954 SpecializationStats::clear(); | |
4955 if (PrintGCDetails) { | |
4956 gclog_or_tty->print("[YG occupancy: "SIZE_FORMAT" K ("SIZE_FORMAT" K)]", | |
4957 _young_gen->used() / K, | |
4958 _young_gen->capacity() / K); | |
4959 } | |
4960 if (asynch) { | |
4961 if (CMSScavengeBeforeRemark) { | |
4962 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
4963 // Temporarily set flag to false, GCH->do_collection will | |
4964 // expect it to be false and set to true | |
4965 FlagSetting fl(gch->_is_gc_active, false); | |
10405 | 4966 NOT_PRODUCT(GCTraceTime t("Scavenge-Before-Remark", |
4967 PrintGCDetails && Verbose, true, _gc_timer_cm);) | |
0 | 4968 int level = _cmsGen->level() - 1; |
4969 if (level >= 0) { | |
4970 gch->do_collection(true, // full (i.e. force, see below) | |
4971 false, // !clear_all_soft_refs | |
4972 0, // size | |
4973 false, // is_tlab | |
4974 level // max_level | |
4975 ); | |
4976 } | |
4977 } | |
4978 FreelistLocker x(this); | |
4979 MutexLockerEx y(bitMapLock(), | |
4980 Mutex::_no_safepoint_check_flag); | |
4981 assert(!init_mark_was_synchronous, "but that's impossible!"); | |
4982 checkpointRootsFinalWork(asynch, clear_all_soft_refs, false); | |
4983 } else { | |
4984 // already have all the locks | |
4985 checkpointRootsFinalWork(asynch, clear_all_soft_refs, | |
4986 init_mark_was_synchronous); | |
4987 } | |
4988 verify_work_stacks_empty(); | |
4989 verify_overflow_empty(); | |
4990 SpecializationStats::print(); | |
4991 } | |
4992 | |
4993 void CMSCollector::checkpointRootsFinalWork(bool asynch, | |
4994 bool clear_all_soft_refs, bool init_mark_was_synchronous) { | |
4995 | |
10405 | 4996 NOT_PRODUCT(GCTraceTime tr("checkpointRootsFinalWork", PrintGCDetails, false, _gc_timer_cm);) |
0 | 4997 |
4998 assert(haveFreelistLocks(), "must have free list locks"); | |
4999 assert_lock_strong(bitMapLock()); | |
5000 | |
5001 if (UseAdaptiveSizePolicy) { | |
5002 size_policy()->checkpoint_roots_final_begin(); | |
5003 } | |
5004 | |
5005 ResourceMark rm; | |
5006 HandleMark hm; | |
5007 | |
5008 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
5009 | |
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5010 if (should_unload_classes()) { |
0 | 5011 CodeCache::gc_prologue(); |
5012 } | |
5013 assert(haveFreelistLocks(), "must have free list locks"); | |
5014 assert_lock_strong(bitMapLock()); | |
5015 | |
5016 if (!init_mark_was_synchronous) { | |
5017 // We might assume that we need not fill TLAB's when | |
5018 // CMSScavengeBeforeRemark is set, because we may have just done | |
5019 // a scavenge which would have filled all TLAB's -- and besides | |
5020 // Eden would be empty. This however may not always be the case -- | |
5021 // for instance although we asked for a scavenge, it may not have | |
5022 // happened because of a JNI critical section. We probably need | |
5023 // a policy for deciding whether we can in that case wait until | |
5024 // the critical section releases and then do the remark following | |
5025 // the scavenge, and skip it here. In the absence of that policy, | |
5026 // or of an indication of whether the scavenge did indeed occur, | |
5027 // we cannot rely on TLAB's having been filled and must do | |
5028 // so here just in case a scavenge did not happen. | |
5029 gch->ensure_parsability(false); // fill TLAB's, but no need to retire them | |
5030 // Update the saved marks which may affect the root scans. | |
5031 gch->save_marks(); | |
5032 | |
5033 { | |
5034 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact;) | |
5035 | |
5036 // Note on the role of the mod union table: | |
5037 // Since the marker in "markFromRoots" marks concurrently with | |
5038 // mutators, it is possible for some reachable objects not to have been | |
5039 // scanned. For instance, an only reference to an object A was | |
5040 // placed in object B after the marker scanned B. Unless B is rescanned, | |
5041 // A would be collected. Such updates to references in marked objects | |
5042 // are detected via the mod union table which is the set of all cards | |
5043 // dirtied since the first checkpoint in this GC cycle and prior to | |
5044 // the most recent young generation GC, minus those cleaned up by the | |
5045 // concurrent precleaning. | |
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5046 if (CMSParallelRemarkEnabled && CollectedHeap::use_parallel_gc_threads()) { |
10405 | 5047 GCTraceTime t("Rescan (parallel) ", PrintGCDetails, false, _gc_timer_cm); |
0 | 5048 do_remark_parallel(); |
5049 } else { | |
10405 | 5050 GCTraceTime t("Rescan (non-parallel) ", PrintGCDetails, false, |
5051 _gc_timer_cm); | |
0 | 5052 do_remark_non_parallel(); |
5053 } | |
5054 } | |
5055 } else { | |
5056 assert(!asynch, "Can't have init_mark_was_synchronous in asynch mode"); | |
5057 // The initial mark was stop-world, so there's no rescanning to | |
5058 // do; go straight on to the next step below. | |
5059 } | |
5060 verify_work_stacks_empty(); | |
5061 verify_overflow_empty(); | |
5062 | |
5063 { | |
10405 | 5064 NOT_PRODUCT(GCTraceTime ts("refProcessingWork", PrintGCDetails, false, _gc_timer_cm);) |
0 | 5065 refProcessingWork(asynch, clear_all_soft_refs); |
5066 } | |
5067 verify_work_stacks_empty(); | |
5068 verify_overflow_empty(); | |
5069 | |
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|
5070 if (should_unload_classes()) { |
0 | 5071 CodeCache::gc_epilogue(); |
5072 } | |
2147
9afee0b9fc1d
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5073 JvmtiExport::gc_epilogue(); |
0 | 5074 |
5075 // If we encountered any (marking stack / work queue) overflow | |
5076 // events during the current CMS cycle, take appropriate | |
5077 // remedial measures, where possible, so as to try and avoid | |
5078 // recurrence of that condition. | |
5079 assert(_markStack.isEmpty(), "No grey objects"); | |
5080 size_t ser_ovflw = _ser_pmc_remark_ovflw + _ser_pmc_preclean_ovflw + | |
452
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changeset
|
5081 _ser_kac_ovflw + _ser_kac_preclean_ovflw; |
0 | 5082 if (ser_ovflw > 0) { |
5083 if (PrintCMSStatistics != 0) { | |
5084 gclog_or_tty->print_cr("Marking stack overflow (benign) " | |
452
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|
5085 "(pmc_pc="SIZE_FORMAT", pmc_rm="SIZE_FORMAT", kac="SIZE_FORMAT |
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|
5086 ", kac_preclean="SIZE_FORMAT")", |
0 | 5087 _ser_pmc_preclean_ovflw, _ser_pmc_remark_ovflw, |
452
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|
5088 _ser_kac_ovflw, _ser_kac_preclean_ovflw); |
0 | 5089 } |
5090 _markStack.expand(); | |
5091 _ser_pmc_remark_ovflw = 0; | |
5092 _ser_pmc_preclean_ovflw = 0; | |
452
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5093 _ser_kac_preclean_ovflw = 0; |
0 | 5094 _ser_kac_ovflw = 0; |
5095 } | |
5096 if (_par_pmc_remark_ovflw > 0 || _par_kac_ovflw > 0) { | |
5097 if (PrintCMSStatistics != 0) { | |
5098 gclog_or_tty->print_cr("Work queue overflow (benign) " | |
5099 "(pmc_rm="SIZE_FORMAT", kac="SIZE_FORMAT")", | |
5100 _par_pmc_remark_ovflw, _par_kac_ovflw); | |
5101 } | |
5102 _par_pmc_remark_ovflw = 0; | |
5103 _par_kac_ovflw = 0; | |
5104 } | |
5105 if (PrintCMSStatistics != 0) { | |
5106 if (_markStack._hit_limit > 0) { | |
5107 gclog_or_tty->print_cr(" (benign) Hit max stack size limit ("SIZE_FORMAT")", | |
5108 _markStack._hit_limit); | |
5109 } | |
5110 if (_markStack._failed_double > 0) { | |
5111 gclog_or_tty->print_cr(" (benign) Failed stack doubling ("SIZE_FORMAT")," | |
5112 " current capacity "SIZE_FORMAT, | |
5113 _markStack._failed_double, | |
5114 _markStack.capacity()); | |
5115 } | |
5116 } | |
5117 _markStack._hit_limit = 0; | |
5118 _markStack._failed_double = 0; | |
5119 | |
5120 if ((VerifyAfterGC || VerifyDuringGC) && | |
5121 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
5122 verify_after_remark(); | |
5123 } | |
5124 | |
10405 | 5125 _gc_tracer_cm->report_object_count_after_gc(&_is_alive_closure); |
5126 | |
0 | 5127 // Change under the freelistLocks. |
5128 _collectorState = Sweeping; | |
5129 // Call isAllClear() under bitMapLock | |
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5130 assert(_modUnionTable.isAllClear(), |
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5131 "Should be clear by end of the final marking"); |
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5132 assert(_ct->klass_rem_set()->mod_union_is_clear(), |
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5133 "Should be clear by end of the final marking"); |
0 | 5134 if (UseAdaptiveSizePolicy) { |
5135 size_policy()->checkpoint_roots_final_end(gch->gc_cause()); | |
5136 } | |
5137 } | |
5138 | |
5139 // Parallel remark task | |
5140 class CMSParRemarkTask: public AbstractGangTask { | |
5141 CMSCollector* _collector; | |
5142 int _n_workers; | |
5143 CompactibleFreeListSpace* _cms_space; | |
5144 | |
5145 // The per-thread work queues, available here for stealing. | |
5146 OopTaskQueueSet* _task_queues; | |
5147 ParallelTaskTerminator _term; | |
5148 | |
5149 public: | |
4095
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
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5150 // A value of 0 passed to n_workers will cause the number of |
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
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5151 // workers to be taken from the active workers in the work gang. |
0 | 5152 CMSParRemarkTask(CMSCollector* collector, |
5153 CompactibleFreeListSpace* cms_space, | |
1833
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5154 int n_workers, FlexibleWorkGang* workers, |
0 | 5155 OopTaskQueueSet* task_queues): |
5156 AbstractGangTask("Rescan roots and grey objects in parallel"), | |
5157 _collector(collector), | |
6725
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5158 _cms_space(cms_space), |
0 | 5159 _n_workers(n_workers), |
5160 _task_queues(task_queues), | |
1833
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5161 _term(n_workers, task_queues) { } |
0 | 5162 |
5163 OopTaskQueueSet* task_queues() { return _task_queues; } | |
5164 | |
5165 OopTaskQueue* work_queue(int i) { return task_queues()->queue(i); } | |
5166 | |
5167 ParallelTaskTerminator* terminator() { return &_term; } | |
1833
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5168 int n_workers() { return _n_workers; } |
0 | 5169 |
4728
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5170 void work(uint worker_id); |
0 | 5171 |
5172 private: | |
5173 // Work method in support of parallel rescan ... of young gen spaces | |
5174 void do_young_space_rescan(int i, Par_MarkRefsIntoAndScanClosure* cl, | |
5175 ContiguousSpace* space, | |
5176 HeapWord** chunk_array, size_t chunk_top); | |
5177 | |
5178 // ... of dirty cards in old space | |
5179 void do_dirty_card_rescan_tasks(CompactibleFreeListSpace* sp, int i, | |
5180 Par_MarkRefsIntoAndScanClosure* cl); | |
5181 | |
5182 // ... work stealing for the above | |
5183 void do_work_steal(int i, Par_MarkRefsIntoAndScanClosure* cl, int* seed); | |
5184 }; | |
5185 | |
6725
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5186 class RemarkKlassClosure : public KlassClosure { |
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5187 CMKlassClosure _cm_klass_closure; |
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5188 public: |
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5189 RemarkKlassClosure(OopClosure* oop_closure) : _cm_klass_closure(oop_closure) {} |
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5190 void do_klass(Klass* k) { |
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5191 // Check if we have modified any oops in the Klass during the concurrent marking. |
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5192 if (k->has_accumulated_modified_oops()) { |
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5193 k->clear_accumulated_modified_oops(); |
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5194 |
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5195 // We could have transfered the current modified marks to the accumulated marks, |
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5196 // like we do with the Card Table to Mod Union Table. But it's not really necessary. |
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5197 } else if (k->has_modified_oops()) { |
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5198 // Don't clear anything, this info is needed by the next young collection. |
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5199 } else { |
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5200 // No modified oops in the Klass. |
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|
5201 return; |
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|
5202 } |
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5203 |
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5204 // The klass has modified fields, need to scan the klass. |
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5205 _cm_klass_closure.do_klass(k); |
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5206 } |
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|
5207 }; |
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5208 |
1833
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|
5209 // work_queue(i) is passed to the closure |
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5210 // Par_MarkRefsIntoAndScanClosure. The "i" parameter |
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|
5211 // also is passed to do_dirty_card_rescan_tasks() and to |
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|
5212 // do_work_steal() to select the i-th task_queue. |
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5213 |
4728
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|
5214 void CMSParRemarkTask::work(uint worker_id) { |
0 | 5215 elapsedTimer _timer; |
5216 ResourceMark rm; | |
5217 HandleMark hm; | |
5218 | |
5219 // ---------- rescan from roots -------------- | |
5220 _timer.start(); | |
5221 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
5222 Par_MarkRefsIntoAndScanClosure par_mrias_cl(_collector, | |
5223 _collector->_span, _collector->ref_processor(), | |
5224 &(_collector->_markBitMap), | |
6725
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5225 work_queue(worker_id)); |
0 | 5226 |
5227 // Rescan young gen roots first since these are likely | |
5228 // coarsely partitioned and may, on that account, constitute | |
5229 // the critical path; thus, it's best to start off that | |
5230 // work first. | |
5231 // ---------- young gen roots -------------- | |
5232 { | |
5233 DefNewGeneration* dng = _collector->_young_gen->as_DefNewGeneration(); | |
5234 EdenSpace* eden_space = dng->eden(); | |
5235 ContiguousSpace* from_space = dng->from(); | |
5236 ContiguousSpace* to_space = dng->to(); | |
5237 | |
5238 HeapWord** eca = _collector->_eden_chunk_array; | |
5239 size_t ect = _collector->_eden_chunk_index; | |
5240 HeapWord** sca = _collector->_survivor_chunk_array; | |
5241 size_t sct = _collector->_survivor_chunk_index; | |
5242 | |
5243 assert(ect <= _collector->_eden_chunk_capacity, "out of bounds"); | |
5244 assert(sct <= _collector->_survivor_chunk_capacity, "out of bounds"); | |
5245 | |
4728
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|
5246 do_young_space_rescan(worker_id, &par_mrias_cl, to_space, NULL, 0); |
441e946dc1af
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|
5247 do_young_space_rescan(worker_id, &par_mrias_cl, from_space, sca, sct); |
441e946dc1af
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|
5248 do_young_space_rescan(worker_id, &par_mrias_cl, eden_space, eca, ect); |
0 | 5249 |
5250 _timer.stop(); | |
5251 if (PrintCMSStatistics != 0) { | |
5252 gclog_or_tty->print_cr( | |
5253 "Finished young gen rescan work in %dth thread: %3.3f sec", | |
4728
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|
5254 worker_id, _timer.seconds()); |
0 | 5255 } |
5256 } | |
5257 | |
5258 // ---------- remaining roots -------------- | |
5259 _timer.reset(); | |
5260 _timer.start(); | |
5261 gch->gen_process_strong_roots(_collector->_cmsGen->level(), | |
5262 false, // yg was scanned above | |
989
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
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|
5263 false, // this is parallel code |
6725
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5264 false, // not scavenging |
0 | 5265 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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|
5266 &par_mrias_cl, |
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
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diff
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|
5267 true, // walk all of code cache if (so & SO_CodeCache) |
6725
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|
5268 NULL, |
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|
5269 NULL); // The dirty klasses will be handled below |
989
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
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diff
changeset
|
5270 assert(_collector->should_unload_classes() |
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
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diff
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|
5271 || (_collector->CMSCollector::roots_scanning_options() & SharedHeap::SO_CodeCache), |
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
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diff
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|
5272 "if we didn't scan the code cache, we have to be ready to drop nmethods with expired weak oops"); |
0 | 5273 _timer.stop(); |
5274 if (PrintCMSStatistics != 0) { | |
5275 gclog_or_tty->print_cr( | |
5276 "Finished remaining root rescan work in %dth thread: %3.3f sec", | |
4728
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jmasa
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|
5277 worker_id, _timer.seconds()); |
0 | 5278 } |
5279 | |
6725
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|
5280 // ---------- unhandled CLD scanning ---------- |
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|
5281 if (worker_id == 0) { // Single threaded at the moment. |
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|
5282 _timer.reset(); |
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|
5283 _timer.start(); |
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|
5284 |
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|
5285 // Scan all new class loader data objects and new dependencies that were |
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|
5286 // introduced during concurrent marking. |
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|
5287 ResourceMark rm; |
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|
5288 GrowableArray<ClassLoaderData*>* array = ClassLoaderDataGraph::new_clds(); |
da91efe96a93
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|
5289 for (int i = 0; i < array->length(); i++) { |
da91efe96a93
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|
5290 par_mrias_cl.do_class_loader_data(array->at(i)); |
da91efe96a93
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|
5291 } |
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|
5292 |
da91efe96a93
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|
5293 // We don't need to keep track of new CLDs anymore. |
da91efe96a93
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|
5294 ClassLoaderDataGraph::remember_new_clds(false); |
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|
5295 |
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|
5296 _timer.stop(); |
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|
5297 if (PrintCMSStatistics != 0) { |
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|
5298 gclog_or_tty->print_cr( |
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|
5299 "Finished unhandled CLD scanning work in %dth thread: %3.3f sec", |
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|
5300 worker_id, _timer.seconds()); |
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|
5301 } |
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|
5302 } |
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|
5303 |
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5304 // ---------- dirty klass scanning ---------- |
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5305 if (worker_id == 0) { // Single threaded at the moment. |
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5306 _timer.reset(); |
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5307 _timer.start(); |
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5308 |
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5309 // Scan all classes that was dirtied during the concurrent marking phase. |
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5310 RemarkKlassClosure remark_klass_closure(&par_mrias_cl); |
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5311 ClassLoaderDataGraph::classes_do(&remark_klass_closure); |
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5312 |
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5313 _timer.stop(); |
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5314 if (PrintCMSStatistics != 0) { |
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5315 gclog_or_tty->print_cr( |
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5316 "Finished dirty klass scanning work in %dth thread: %3.3f sec", |
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5317 worker_id, _timer.seconds()); |
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5318 } |
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5319 } |
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5320 |
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5321 // We might have added oops to ClassLoaderData::_handles during the |
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5322 // concurrent marking phase. These oops point to newly allocated objects |
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5323 // that are guaranteed to be kept alive. Either by the direct allocation |
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5324 // code, or when the young collector processes the strong roots. Hence, |
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5325 // we don't have to revisit the _handles block during the remark phase. |
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5326 |
0 | 5327 // ---------- rescan dirty cards ------------ |
5328 _timer.reset(); | |
5329 _timer.start(); | |
5330 | |
5331 // Do the rescan tasks for each of the two spaces | |
6725
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5332 // (cms_space) in turn. |
4728
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5333 // "worker_id" is passed to select the task_queue for "worker_id" |
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5334 do_dirty_card_rescan_tasks(_cms_space, worker_id, &par_mrias_cl); |
0 | 5335 _timer.stop(); |
5336 if (PrintCMSStatistics != 0) { | |
5337 gclog_or_tty->print_cr( | |
5338 "Finished dirty card rescan work in %dth thread: %3.3f sec", | |
4728
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5339 worker_id, _timer.seconds()); |
0 | 5340 } |
5341 | |
5342 // ---------- steal work from other threads ... | |
5343 // ---------- ... and drain overflow list. | |
5344 _timer.reset(); | |
5345 _timer.start(); | |
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5346 do_work_steal(worker_id, &par_mrias_cl, _collector->hash_seed(worker_id)); |
0 | 5347 _timer.stop(); |
5348 if (PrintCMSStatistics != 0) { | |
5349 gclog_or_tty->print_cr( | |
5350 "Finished work stealing in %dth thread: %3.3f sec", | |
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5351 worker_id, _timer.seconds()); |
0 | 5352 } |
5353 } | |
5354 | |
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5355 // Note that parameter "i" is not used. |
0 | 5356 void |
5357 CMSParRemarkTask::do_young_space_rescan(int i, | |
5358 Par_MarkRefsIntoAndScanClosure* cl, ContiguousSpace* space, | |
5359 HeapWord** chunk_array, size_t chunk_top) { | |
5360 // Until all tasks completed: | |
5361 // . claim an unclaimed task | |
5362 // . compute region boundaries corresponding to task claimed | |
5363 // using chunk_array | |
5364 // . par_oop_iterate(cl) over that region | |
5365 | |
5366 ResourceMark rm; | |
5367 HandleMark hm; | |
5368 | |
5369 SequentialSubTasksDone* pst = space->par_seq_tasks(); | |
5370 assert(pst->valid(), "Uninitialized use?"); | |
5371 | |
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5372 uint nth_task = 0; |
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5373 uint n_tasks = pst->n_tasks(); |
0 | 5374 |
5375 HeapWord *start, *end; | |
5376 while (!pst->is_task_claimed(/* reference */ nth_task)) { | |
5377 // We claimed task # nth_task; compute its boundaries. | |
5378 if (chunk_top == 0) { // no samples were taken | |
5379 assert(nth_task == 0 && n_tasks == 1, "Can have only 1 EdenSpace task"); | |
5380 start = space->bottom(); | |
5381 end = space->top(); | |
5382 } else if (nth_task == 0) { | |
5383 start = space->bottom(); | |
5384 end = chunk_array[nth_task]; | |
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5385 } else if (nth_task < (uint)chunk_top) { |
0 | 5386 assert(nth_task >= 1, "Control point invariant"); |
5387 start = chunk_array[nth_task - 1]; | |
5388 end = chunk_array[nth_task]; | |
5389 } else { | |
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5390 assert(nth_task == (uint)chunk_top, "Control point invariant"); |
0 | 5391 start = chunk_array[chunk_top - 1]; |
5392 end = space->top(); | |
5393 } | |
5394 MemRegion mr(start, end); | |
5395 // Verify that mr is in space | |
5396 assert(mr.is_empty() || space->used_region().contains(mr), | |
5397 "Should be in space"); | |
5398 // Verify that "start" is an object boundary | |
5399 assert(mr.is_empty() || oop(mr.start())->is_oop(), | |
5400 "Should be an oop"); | |
5401 space->par_oop_iterate(mr, cl); | |
5402 } | |
5403 pst->all_tasks_completed(); | |
5404 } | |
5405 | |
5406 void | |
5407 CMSParRemarkTask::do_dirty_card_rescan_tasks( | |
5408 CompactibleFreeListSpace* sp, int i, | |
5409 Par_MarkRefsIntoAndScanClosure* cl) { | |
5410 // Until all tasks completed: | |
5411 // . claim an unclaimed task | |
5412 // . compute region boundaries corresponding to task claimed | |
5413 // . transfer dirty bits ct->mut for that region | |
5414 // . apply rescanclosure to dirty mut bits for that region | |
5415 | |
5416 ResourceMark rm; | |
5417 HandleMark hm; | |
5418 | |
5419 OopTaskQueue* work_q = work_queue(i); | |
5420 ModUnionClosure modUnionClosure(&(_collector->_modUnionTable)); | |
5421 // CAUTION! CAUTION! CAUTION! CAUTION! CAUTION! CAUTION! CAUTION! | |
5422 // CAUTION: This closure has state that persists across calls to | |
5423 // the work method dirty_range_iterate_clear() in that it has | |
5424 // imbedded in it a (subtype of) UpwardsObjectClosure. The | |
5425 // use of that state in the imbedded UpwardsObjectClosure instance | |
5426 // assumes that the cards are always iterated (even if in parallel | |
5427 // by several threads) in monotonically increasing order per each | |
5428 // thread. This is true of the implementation below which picks | |
5429 // card ranges (chunks) in monotonically increasing order globally | |
5430 // and, a-fortiori, in monotonically increasing order per thread | |
5431 // (the latter order being a subsequence of the former). | |
5432 // If the work code below is ever reorganized into a more chaotic | |
5433 // work-partitioning form than the current "sequential tasks" | |
5434 // paradigm, the use of that persistent state will have to be | |
5435 // revisited and modified appropriately. See also related | |
5436 // bug 4756801 work on which should examine this code to make | |
5437 // sure that the changes there do not run counter to the | |
5438 // assumptions made here and necessary for correctness and | |
5439 // efficiency. Note also that this code might yield inefficient | |
5440 // behaviour in the case of very large objects that span one or | |
5441 // more work chunks. Such objects would potentially be scanned | |
5442 // several times redundantly. Work on 4756801 should try and | |
5443 // address that performance anomaly if at all possible. XXX | |
5444 MemRegion full_span = _collector->_span; | |
5445 CMSBitMap* bm = &(_collector->_markBitMap); // shared | |
5446 MarkFromDirtyCardsClosure | |
5447 greyRescanClosure(_collector, full_span, // entire span of interest | |
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5448 sp, bm, work_q, cl); |
0 | 5449 |
5450 SequentialSubTasksDone* pst = sp->conc_par_seq_tasks(); | |
5451 assert(pst->valid(), "Uninitialized use?"); | |
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5452 uint nth_task = 0; |
0 | 5453 const int alignment = CardTableModRefBS::card_size * BitsPerWord; |
5454 MemRegion span = sp->used_region(); | |
5455 HeapWord* start_addr = span.start(); | |
5456 HeapWord* end_addr = (HeapWord*)round_to((intptr_t)span.end(), | |
5457 alignment); | |
5458 const size_t chunk_size = sp->rescan_task_size(); // in HeapWord units | |
5459 assert((HeapWord*)round_to((intptr_t)start_addr, alignment) == | |
5460 start_addr, "Check alignment"); | |
5461 assert((size_t)round_to((intptr_t)chunk_size, alignment) == | |
5462 chunk_size, "Check alignment"); | |
5463 | |
5464 while (!pst->is_task_claimed(/* reference */ nth_task)) { | |
5465 // Having claimed the nth_task, compute corresponding mem-region, | |
5466 // which is a-fortiori aligned correctly (i.e. at a MUT bopundary). | |
5467 // The alignment restriction ensures that we do not need any | |
5468 // synchronization with other gang-workers while setting or | |
5469 // clearing bits in thus chunk of the MUT. | |
5470 MemRegion this_span = MemRegion(start_addr + nth_task*chunk_size, | |
5471 start_addr + (nth_task+1)*chunk_size); | |
5472 // The last chunk's end might be way beyond end of the | |
5473 // used region. In that case pull back appropriately. | |
5474 if (this_span.end() > end_addr) { | |
5475 this_span.set_end(end_addr); | |
5476 assert(!this_span.is_empty(), "Program logic (calculation of n_tasks)"); | |
5477 } | |
5478 // Iterate over the dirty cards covering this chunk, marking them | |
5479 // precleaned, and setting the corresponding bits in the mod union | |
5480 // table. Since we have been careful to partition at Card and MUT-word | |
5481 // boundaries no synchronization is needed between parallel threads. | |
5482 _collector->_ct->ct_bs()->dirty_card_iterate(this_span, | |
5483 &modUnionClosure); | |
5484 | |
5485 // Having transferred these marks into the modUnionTable, | |
5486 // rescan the marked objects on the dirty cards in the modUnionTable. | |
5487 // Even if this is at a synchronous collection, the initial marking | |
5488 // may have been done during an asynchronous collection so there | |
5489 // may be dirty bits in the mod-union table. | |
5490 _collector->_modUnionTable.dirty_range_iterate_clear( | |
5491 this_span, &greyRescanClosure); | |
5492 _collector->_modUnionTable.verifyNoOneBitsInRange( | |
5493 this_span.start(), | |
5494 this_span.end()); | |
5495 } | |
5496 pst->all_tasks_completed(); // declare that i am done | |
5497 } | |
5498 | |
5499 // . see if we can share work_queues with ParNew? XXX | |
5500 void | |
5501 CMSParRemarkTask::do_work_steal(int i, Par_MarkRefsIntoAndScanClosure* cl, | |
5502 int* seed) { | |
5503 OopTaskQueue* work_q = work_queue(i); | |
5504 NOT_PRODUCT(int num_steals = 0;) | |
5505 oop obj_to_scan; | |
5506 CMSBitMap* bm = &(_collector->_markBitMap); | |
5507 | |
5508 while (true) { | |
5509 // Completely finish any left over work from (an) earlier round(s) | |
5510 cl->trim_queue(0); | |
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5511 size_t num_from_overflow_list = MIN2((size_t)(work_q->max_elems() - work_q->size())/4, |
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5512 (size_t)ParGCDesiredObjsFromOverflowList); |
0 | 5513 // Now check if there's any work in the overflow list |
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5514 // Passing ParallelGCThreads as the third parameter, no_of_gc_threads, |
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5515 // only affects the number of attempts made to get work from the |
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5516 // overflow list and does not affect the number of workers. Just |
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5517 // pass ParallelGCThreads so this behavior is unchanged. |
0 | 5518 if (_collector->par_take_from_overflow_list(num_from_overflow_list, |
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5519 work_q, |
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5520 ParallelGCThreads)) { |
0 | 5521 // found something in global overflow list; |
5522 // not yet ready to go stealing work from others. | |
5523 // We'd like to assert(work_q->size() != 0, ...) | |
5524 // because we just took work from the overflow list, | |
5525 // but of course we can't since all of that could have | |
5526 // been already stolen from us. | |
5527 // "He giveth and He taketh away." | |
5528 continue; | |
5529 } | |
5530 // Verify that we have no work before we resort to stealing | |
5531 assert(work_q->size() == 0, "Have work, shouldn't steal"); | |
5532 // Try to steal from other queues that have work | |
5533 if (task_queues()->steal(i, seed, /* reference */ obj_to_scan)) { | |
5534 NOT_PRODUCT(num_steals++;) | |
5535 assert(obj_to_scan->is_oop(), "Oops, not an oop!"); | |
5536 assert(bm->isMarked((HeapWord*)obj_to_scan), "Stole an unmarked oop?"); | |
5537 // Do scanning work | |
5538 obj_to_scan->oop_iterate(cl); | |
5539 // Loop around, finish this work, and try to steal some more | |
5540 } else if (terminator()->offer_termination()) { | |
5541 break; // nirvana from the infinite cycle | |
5542 } | |
5543 } | |
5544 NOT_PRODUCT( | |
5545 if (PrintCMSStatistics != 0) { | |
5546 gclog_or_tty->print("\n\t(%d: stole %d oops)", i, num_steals); | |
5547 } | |
5548 ) | |
5549 assert(work_q->size() == 0 && _collector->overflow_list_is_empty(), | |
5550 "Else our work is not yet done"); | |
5551 } | |
5552 | |
5553 // Return a thread-local PLAB recording array, as appropriate. | |
5554 void* CMSCollector::get_data_recorder(int thr_num) { | |
5555 if (_survivor_plab_array != NULL && | |
5556 (CMSPLABRecordAlways || | |
5557 (_collectorState > Marking && _collectorState < FinalMarking))) { | |
5558 assert(thr_num < (int)ParallelGCThreads, "thr_num is out of bounds"); | |
5559 ChunkArray* ca = &_survivor_plab_array[thr_num]; | |
5560 ca->reset(); // clear it so that fresh data is recorded | |
5561 return (void*) ca; | |
5562 } else { | |
5563 return NULL; | |
5564 } | |
5565 } | |
5566 | |
5567 // Reset all the thread-local PLAB recording arrays | |
5568 void CMSCollector::reset_survivor_plab_arrays() { | |
5569 for (uint i = 0; i < ParallelGCThreads; i++) { | |
5570 _survivor_plab_array[i].reset(); | |
5571 } | |
5572 } | |
5573 | |
5574 // Merge the per-thread plab arrays into the global survivor chunk | |
5575 // array which will provide the partitioning of the survivor space | |
5576 // for CMS rescan. | |
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5577 void CMSCollector::merge_survivor_plab_arrays(ContiguousSpace* surv, |
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5578 int no_of_gc_threads) { |
0 | 5579 assert(_survivor_plab_array != NULL, "Error"); |
5580 assert(_survivor_chunk_array != NULL, "Error"); | |
5581 assert(_collectorState == FinalMarking, "Error"); | |
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5582 for (int j = 0; j < no_of_gc_threads; j++) { |
0 | 5583 _cursor[j] = 0; |
5584 } | |
5585 HeapWord* top = surv->top(); | |
5586 size_t i; | |
5587 for (i = 0; i < _survivor_chunk_capacity; i++) { // all sca entries | |
5588 HeapWord* min_val = top; // Higher than any PLAB address | |
5589 uint min_tid = 0; // position of min_val this round | |
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5590 for (int j = 0; j < no_of_gc_threads; j++) { |
0 | 5591 ChunkArray* cur_sca = &_survivor_plab_array[j]; |
5592 if (_cursor[j] == cur_sca->end()) { | |
5593 continue; | |
5594 } | |
5595 assert(_cursor[j] < cur_sca->end(), "ctl pt invariant"); | |
5596 HeapWord* cur_val = cur_sca->nth(_cursor[j]); | |
5597 assert(surv->used_region().contains(cur_val), "Out of bounds value"); | |
5598 if (cur_val < min_val) { | |
5599 min_tid = j; | |
5600 min_val = cur_val; | |
5601 } else { | |
5602 assert(cur_val < top, "All recorded addresses should be less"); | |
5603 } | |
5604 } | |
5605 // At this point min_val and min_tid are respectively | |
5606 // the least address in _survivor_plab_array[j]->nth(_cursor[j]) | |
5607 // and the thread (j) that witnesses that address. | |
5608 // We record this address in the _survivor_chunk_array[i] | |
5609 // and increment _cursor[min_tid] prior to the next round i. | |
5610 if (min_val == top) { | |
5611 break; | |
5612 } | |
5613 _survivor_chunk_array[i] = min_val; | |
5614 _cursor[min_tid]++; | |
5615 } | |
5616 // We are all done; record the size of the _survivor_chunk_array | |
5617 _survivor_chunk_index = i; // exclusive: [0, i) | |
5618 if (PrintCMSStatistics > 0) { | |
5619 gclog_or_tty->print(" (Survivor:" SIZE_FORMAT "chunks) ", i); | |
5620 } | |
5621 // Verify that we used up all the recorded entries | |
5622 #ifdef ASSERT | |
5623 size_t total = 0; | |
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5624 for (int j = 0; j < no_of_gc_threads; j++) { |
0 | 5625 assert(_cursor[j] == _survivor_plab_array[j].end(), "Ctl pt invariant"); |
5626 total += _cursor[j]; | |
5627 } | |
5628 assert(total == _survivor_chunk_index, "Ctl Pt Invariant"); | |
5629 // Check that the merged array is in sorted order | |
5630 if (total > 0) { | |
5631 for (size_t i = 0; i < total - 1; i++) { | |
5632 if (PrintCMSStatistics > 0) { | |
5633 gclog_or_tty->print(" (chunk" SIZE_FORMAT ":" INTPTR_FORMAT ") ", | |
5634 i, _survivor_chunk_array[i]); | |
5635 } | |
5636 assert(_survivor_chunk_array[i] < _survivor_chunk_array[i+1], | |
5637 "Not sorted"); | |
5638 } | |
5639 } | |
5640 #endif // ASSERT | |
5641 } | |
5642 | |
5643 // Set up the space's par_seq_tasks structure for work claiming | |
5644 // for parallel rescan of young gen. | |
5645 // See ParRescanTask where this is currently used. | |
5646 void | |
5647 CMSCollector:: | |
5648 initialize_sequential_subtasks_for_young_gen_rescan(int n_threads) { | |
5649 assert(n_threads > 0, "Unexpected n_threads argument"); | |
5650 DefNewGeneration* dng = (DefNewGeneration*)_young_gen; | |
5651 | |
5652 // Eden space | |
5653 { | |
5654 SequentialSubTasksDone* pst = dng->eden()->par_seq_tasks(); | |
5655 assert(!pst->valid(), "Clobbering existing data?"); | |
5656 // Each valid entry in [0, _eden_chunk_index) represents a task. | |
5657 size_t n_tasks = _eden_chunk_index + 1; | |
5658 assert(n_tasks == 1 || _eden_chunk_array != NULL, "Error"); | |
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5659 // Sets the condition for completion of the subtask (how many threads |
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5660 // need to finish in order to be done). |
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5661 pst->set_n_threads(n_threads); |
0 | 5662 pst->set_n_tasks((int)n_tasks); |
5663 } | |
5664 | |
5665 // Merge the survivor plab arrays into _survivor_chunk_array | |
5666 if (_survivor_plab_array != NULL) { | |
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5667 merge_survivor_plab_arrays(dng->from(), n_threads); |
0 | 5668 } else { |
5669 assert(_survivor_chunk_index == 0, "Error"); | |
5670 } | |
5671 | |
5672 // To space | |
5673 { | |
5674 SequentialSubTasksDone* pst = dng->to()->par_seq_tasks(); | |
5675 assert(!pst->valid(), "Clobbering existing data?"); | |
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5676 // Sets the condition for completion of the subtask (how many threads |
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5677 // need to finish in order to be done). |
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5678 pst->set_n_threads(n_threads); |
0 | 5679 pst->set_n_tasks(1); |
5680 assert(pst->valid(), "Error"); | |
5681 } | |
5682 | |
5683 // From space | |
5684 { | |
5685 SequentialSubTasksDone* pst = dng->from()->par_seq_tasks(); | |
5686 assert(!pst->valid(), "Clobbering existing data?"); | |
5687 size_t n_tasks = _survivor_chunk_index + 1; | |
5688 assert(n_tasks == 1 || _survivor_chunk_array != NULL, "Error"); | |
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5689 // Sets the condition for completion of the subtask (how many threads |
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5690 // need to finish in order to be done). |
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5691 pst->set_n_threads(n_threads); |
0 | 5692 pst->set_n_tasks((int)n_tasks); |
5693 assert(pst->valid(), "Error"); | |
5694 } | |
5695 } | |
5696 | |
5697 // Parallel version of remark | |
5698 void CMSCollector::do_remark_parallel() { | |
5699 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
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5700 FlexibleWorkGang* workers = gch->workers(); |
0 | 5701 assert(workers != NULL, "Need parallel worker threads."); |
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5702 // Choose to use the number of GC workers most recently set |
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5703 // into "active_workers". If active_workers is not set, set it |
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5704 // to ParallelGCThreads. |
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5705 int n_workers = workers->active_workers(); |
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5706 if (n_workers == 0) { |
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5707 assert(n_workers > 0, "Should have been set during scavenge"); |
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5708 n_workers = ParallelGCThreads; |
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5709 workers->set_active_workers(n_workers); |
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5710 } |
0 | 5711 CompactibleFreeListSpace* cms_space = _cmsGen->cmsSpace(); |
5712 | |
5713 CMSParRemarkTask tsk(this, | |
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5714 cms_space, |
0 | 5715 n_workers, workers, task_queues()); |
5716 | |
5717 // Set up for parallel process_strong_roots work. | |
5718 gch->set_par_threads(n_workers); | |
5719 // We won't be iterating over the cards in the card table updating | |
5720 // the younger_gen cards, so we shouldn't call the following else | |
5721 // the verification code as well as subsequent younger_refs_iterate | |
5722 // code would get confused. XXX | |
5723 // gch->rem_set()->prepare_for_younger_refs_iterate(true); // parallel | |
5724 | |
5725 // The young gen rescan work will not be done as part of | |
5726 // process_strong_roots (which currently doesn't knw how to | |
5727 // parallelize such a scan), but rather will be broken up into | |
5728 // a set of parallel tasks (via the sampling that the [abortable] | |
5729 // preclean phase did of EdenSpace, plus the [two] tasks of | |
5730 // scanning the [two] survivor spaces. Further fine-grain | |
5731 // parallelization of the scanning of the survivor spaces | |
5732 // themselves, and of precleaning of the younger gen itself | |
5733 // is deferred to the future. | |
5734 initialize_sequential_subtasks_for_young_gen_rescan(n_workers); | |
5735 | |
5736 // The dirty card rescan work is broken up into a "sequence" | |
5737 // of parallel tasks (per constituent space) that are dynamically | |
5738 // claimed by the parallel threads. | |
5739 cms_space->initialize_sequential_subtasks_for_rescan(n_workers); | |
5740 | |
5741 // It turns out that even when we're using 1 thread, doing the work in a | |
5742 // separate thread causes wide variance in run times. We can't help this | |
5743 // in the multi-threaded case, but we special-case n=1 here to get | |
5744 // repeatable measurements of the 1-thread overhead of the parallel code. | |
5745 if (n_workers > 1) { | |
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5746 // Make refs discovery MT-safe, if it isn't already: it may not |
92da084fefc9
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5747 // necessarily be so, since it's possible that we are doing |
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5748 // ST marking. |
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5749 ReferenceProcessorMTDiscoveryMutator mt(ref_processor(), true); |
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5750 GenCollectedHeap::StrongRootsScope srs(gch); |
0 | 5751 workers->run_task(&tsk); |
5752 } else { | |
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5753 ReferenceProcessorMTDiscoveryMutator mt(ref_processor(), false); |
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5754 GenCollectedHeap::StrongRootsScope srs(gch); |
0 | 5755 tsk.work(0); |
5756 } | |
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5757 |
0 | 5758 gch->set_par_threads(0); // 0 ==> non-parallel. |
5759 // restore, single-threaded for now, any preserved marks | |
5760 // as a result of work_q overflow | |
5761 restore_preserved_marks_if_any(); | |
5762 } | |
5763 | |
5764 // Non-parallel version of remark | |
5765 void CMSCollector::do_remark_non_parallel() { | |
5766 ResourceMark rm; | |
5767 HandleMark hm; | |
5768 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
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5769 ReferenceProcessorMTDiscoveryMutator mt(ref_processor(), false); |
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5770 |
0 | 5771 MarkRefsIntoAndScanClosure |
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5772 mrias_cl(_span, ref_processor(), &_markBitMap, NULL /* not precleaning */, |
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5773 &_markStack, this, |
0 | 5774 false /* should_yield */, false /* not precleaning */); |
5775 MarkFromDirtyCardsClosure | |
5776 markFromDirtyCardsClosure(this, _span, | |
5777 NULL, // space is set further below | |
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5778 &_markBitMap, &_markStack, &mrias_cl); |
0 | 5779 { |
10405 | 5780 GCTraceTime t("grey object rescan", PrintGCDetails, false, _gc_timer_cm); |
342
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5781 // Iterate over the dirty cards, setting the corresponding bits in the |
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|
5782 // mod union table. |
0 | 5783 { |
5784 ModUnionClosure modUnionClosure(&_modUnionTable); | |
5785 _ct->ct_bs()->dirty_card_iterate( | |
5786 _cmsGen->used_region(), | |
5787 &modUnionClosure); | |
5788 } | |
5789 // Having transferred these marks into the modUnionTable, we just need | |
5790 // to rescan the marked objects on the dirty cards in the modUnionTable. | |
5791 // The initial marking may have been done during an asynchronous | |
5792 // collection so there may be dirty bits in the mod-union table. | |
5793 const int alignment = | |
5794 CardTableModRefBS::card_size * BitsPerWord; | |
5795 { | |
5796 // ... First handle dirty cards in CMS gen | |
5797 markFromDirtyCardsClosure.set_space(_cmsGen->cmsSpace()); | |
5798 MemRegion ur = _cmsGen->used_region(); | |
5799 HeapWord* lb = ur.start(); | |
5800 HeapWord* ub = (HeapWord*)round_to((intptr_t)ur.end(), alignment); | |
5801 MemRegion cms_span(lb, ub); | |
5802 _modUnionTable.dirty_range_iterate_clear(cms_span, | |
5803 &markFromDirtyCardsClosure); | |
5804 verify_work_stacks_empty(); | |
5805 if (PrintCMSStatistics != 0) { | |
5806 gclog_or_tty->print(" (re-scanned "SIZE_FORMAT" dirty cards in cms gen) ", | |
5807 markFromDirtyCardsClosure.num_dirty_cards()); | |
5808 } | |
5809 } | |
5810 } | |
5811 if (VerifyDuringGC && | |
5812 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
5813 HandleMark hm; // Discard invalid handles created during verification | |
6865
4202510ee0fe
8000831: Heap verification output incorrect/incomplete
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parents:
6787
diff
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|
5814 Universe::verify(); |
0 | 5815 } |
5816 { | |
10405 | 5817 GCTraceTime t("root rescan", PrintGCDetails, false, _gc_timer_cm); |
0 | 5818 |
5819 verify_work_stacks_empty(); | |
5820 | |
5821 gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel. | |
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|
5822 GenCollectedHeap::StrongRootsScope srs(gch); |
0 | 5823 gch->gen_process_strong_roots(_cmsGen->level(), |
5824 true, // younger gens as roots | |
989
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|
5825 false, // use the local StrongRootsScope |
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5826 false, // not scavenging |
0 | 5827 SharedHeap::ScanningOption(roots_scanning_options()), |
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|
5828 &mrias_cl, |
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|
5829 true, // walk code active on stacks |
6725
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5830 NULL, |
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|
5831 NULL); // The dirty klasses will be handled below |
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5832 |
989
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|
5833 assert(should_unload_classes() |
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|
5834 || (roots_scanning_options() & SharedHeap::SO_CodeCache), |
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|
5835 "if we didn't scan the code cache, we have to be ready to drop nmethods with expired weak oops"); |
0 | 5836 } |
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|
5837 |
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|
5838 { |
10405 | 5839 GCTraceTime t("visit unhandled CLDs", PrintGCDetails, false, _gc_timer_cm); |
6725
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|
5840 |
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|
5841 verify_work_stacks_empty(); |
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|
5842 |
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|
5843 // Scan all class loader data objects that might have been introduced |
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|
5844 // during concurrent marking. |
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|
5845 ResourceMark rm; |
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|
5846 GrowableArray<ClassLoaderData*>* array = ClassLoaderDataGraph::new_clds(); |
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5847 for (int i = 0; i < array->length(); i++) { |
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|
5848 mrias_cl.do_class_loader_data(array->at(i)); |
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|
5849 } |
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|
5850 |
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|
5851 // We don't need to keep track of new CLDs anymore. |
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|
5852 ClassLoaderDataGraph::remember_new_clds(false); |
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|
5853 |
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|
5854 verify_work_stacks_empty(); |
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|
5855 } |
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|
5856 |
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|
5857 { |
10405 | 5858 GCTraceTime t("dirty klass scan", PrintGCDetails, false, _gc_timer_cm); |
6725
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|
5859 |
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|
5860 verify_work_stacks_empty(); |
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|
5861 |
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|
5862 RemarkKlassClosure remark_klass_closure(&mrias_cl); |
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|
5863 ClassLoaderDataGraph::classes_do(&remark_klass_closure); |
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|
5864 |
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|
5865 verify_work_stacks_empty(); |
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|
5866 } |
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|
5867 |
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|
5868 // We might have added oops to ClassLoaderData::_handles during the |
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|
5869 // concurrent marking phase. These oops point to newly allocated objects |
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|
5870 // that are guaranteed to be kept alive. Either by the direct allocation |
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|
5871 // code, or when the young collector processes the strong roots. Hence, |
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|
5872 // we don't have to revisit the _handles block during the remark phase. |
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|
5873 |
0 | 5874 verify_work_stacks_empty(); |
5875 // Restore evacuated mark words, if any, used for overflow list links | |
5876 if (!CMSOverflowEarlyRestoration) { | |
5877 restore_preserved_marks_if_any(); | |
5878 } | |
5879 verify_overflow_empty(); | |
5880 } | |
5881 | |
5882 //////////////////////////////////////////////////////// | |
5883 // Parallel Reference Processing Task Proxy Class | |
5884 //////////////////////////////////////////////////////// | |
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5885 class CMSRefProcTaskProxy: public AbstractGangTaskWOopQueues { |
0 | 5886 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; |
5887 CMSCollector* _collector; | |
5888 CMSBitMap* _mark_bit_map; | |
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5889 const MemRegion _span; |
0 | 5890 ProcessTask& _task; |
5891 | |
5892 public: | |
5893 CMSRefProcTaskProxy(ProcessTask& task, | |
5894 CMSCollector* collector, | |
5895 const MemRegion& span, | |
5896 CMSBitMap* mark_bit_map, | |
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5897 AbstractWorkGang* workers, |
0 | 5898 OopTaskQueueSet* task_queues): |
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5899 // XXX Should superclass AGTWOQ also know about AWG since it knows |
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5900 // about the task_queues used by the AWG? Then it could initialize |
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5901 // the terminator() object. See 6984287. The set_for_termination() |
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5902 // below is a temporary band-aid for the regression in 6984287. |
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5903 AbstractGangTaskWOopQueues("Process referents by policy in parallel", |
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5904 task_queues), |
0 | 5905 _task(task), |
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5906 _collector(collector), _span(span), _mark_bit_map(mark_bit_map) |
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5907 { |
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5908 assert(_collector->_span.equals(_span) && !_span.is_empty(), |
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5909 "Inconsistency in _span"); |
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5910 set_for_termination(workers->active_workers()); |
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5911 } |
0 | 5912 |
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5913 OopTaskQueueSet* task_queues() { return queues(); } |
0 | 5914 |
5915 OopTaskQueue* work_queue(int i) { return task_queues()->queue(i); } | |
5916 | |
5917 void do_work_steal(int i, | |
5918 CMSParDrainMarkingStackClosure* drain, | |
5919 CMSParKeepAliveClosure* keep_alive, | |
5920 int* seed); | |
5921 | |
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5922 virtual void work(uint worker_id); |
0 | 5923 }; |
5924 | |
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5925 void CMSRefProcTaskProxy::work(uint worker_id) { |
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5926 assert(_collector->_span.equals(_span), "Inconsistency in _span"); |
0 | 5927 CMSParKeepAliveClosure par_keep_alive(_collector, _span, |
935 | 5928 _mark_bit_map, |
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5929 work_queue(worker_id)); |
0 | 5930 CMSParDrainMarkingStackClosure par_drain_stack(_collector, _span, |
935 | 5931 _mark_bit_map, |
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5932 work_queue(worker_id)); |
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5933 CMSIsAliveClosure is_alive_closure(_span, _mark_bit_map); |
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|
5934 _task.work(worker_id, is_alive_closure, par_keep_alive, par_drain_stack); |
0 | 5935 if (_task.marks_oops_alive()) { |
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|
5936 do_work_steal(worker_id, &par_drain_stack, &par_keep_alive, |
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5937 _collector->hash_seed(worker_id)); |
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|
5938 } |
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|
5939 assert(work_queue(worker_id)->size() == 0, "work_queue should be empty"); |
0 | 5940 assert(_collector->_overflow_list == NULL, "non-empty _overflow_list"); |
5941 } | |
5942 | |
5943 class CMSRefEnqueueTaskProxy: public AbstractGangTask { | |
5944 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; | |
5945 EnqueueTask& _task; | |
5946 | |
5947 public: | |
5948 CMSRefEnqueueTaskProxy(EnqueueTask& task) | |
5949 : AbstractGangTask("Enqueue reference objects in parallel"), | |
5950 _task(task) | |
5951 { } | |
5952 | |
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|
5953 virtual void work(uint worker_id) |
0 | 5954 { |
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|
5955 _task.work(worker_id); |
0 | 5956 } |
5957 }; | |
5958 | |
5959 CMSParKeepAliveClosure::CMSParKeepAliveClosure(CMSCollector* collector, | |
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5960 MemRegion span, CMSBitMap* bit_map, OopTaskQueue* work_queue): |
0 | 5961 _span(span), |
5962 _bit_map(bit_map), | |
5963 _work_queue(work_queue), | |
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5964 _mark_and_push(collector, span, bit_map, work_queue), |
0 | 5965 _low_water_mark(MIN2((uint)(work_queue->max_elems()/4), |
5966 (uint)(CMSWorkQueueDrainThreshold * ParallelGCThreads))) | |
5967 { } | |
5968 | |
5969 // . see if we can share work_queues with ParNew? XXX | |
5970 void CMSRefProcTaskProxy::do_work_steal(int i, | |
5971 CMSParDrainMarkingStackClosure* drain, | |
5972 CMSParKeepAliveClosure* keep_alive, | |
5973 int* seed) { | |
5974 OopTaskQueue* work_q = work_queue(i); | |
5975 NOT_PRODUCT(int num_steals = 0;) | |
5976 oop obj_to_scan; | |
5977 | |
5978 while (true) { | |
5979 // Completely finish any left over work from (an) earlier round(s) | |
5980 drain->trim_queue(0); | |
679
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changeset
|
5981 size_t num_from_overflow_list = MIN2((size_t)(work_q->max_elems() - work_q->size())/4, |
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|
5982 (size_t)ParGCDesiredObjsFromOverflowList); |
0 | 5983 // Now check if there's any work in the overflow list |
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5984 // Passing ParallelGCThreads as the third parameter, no_of_gc_threads, |
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5985 // only affects the number of attempts made to get work from the |
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5986 // overflow list and does not affect the number of workers. Just |
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|
5987 // pass ParallelGCThreads so this behavior is unchanged. |
0 | 5988 if (_collector->par_take_from_overflow_list(num_from_overflow_list, |
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|
5989 work_q, |
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|
5990 ParallelGCThreads)) { |
0 | 5991 // Found something in global overflow list; |
5992 // not yet ready to go stealing work from others. | |
5993 // We'd like to assert(work_q->size() != 0, ...) | |
5994 // because we just took work from the overflow list, | |
5995 // but of course we can't, since all of that might have | |
5996 // been already stolen from us. | |
5997 continue; | |
5998 } | |
5999 // Verify that we have no work before we resort to stealing | |
6000 assert(work_q->size() == 0, "Have work, shouldn't steal"); | |
6001 // Try to steal from other queues that have work | |
6002 if (task_queues()->steal(i, seed, /* reference */ obj_to_scan)) { | |
6003 NOT_PRODUCT(num_steals++;) | |
6004 assert(obj_to_scan->is_oop(), "Oops, not an oop!"); | |
6005 assert(_mark_bit_map->isMarked((HeapWord*)obj_to_scan), "Stole an unmarked oop?"); | |
6006 // Do scanning work | |
6007 obj_to_scan->oop_iterate(keep_alive); | |
6008 // Loop around, finish this work, and try to steal some more | |
6009 } else if (terminator()->offer_termination()) { | |
6010 break; // nirvana from the infinite cycle | |
6011 } | |
6012 } | |
6013 NOT_PRODUCT( | |
6014 if (PrintCMSStatistics != 0) { | |
6015 gclog_or_tty->print("\n\t(%d: stole %d oops)", i, num_steals); | |
6016 } | |
6017 ) | |
6018 } | |
6019 | |
6020 void CMSRefProcTaskExecutor::execute(ProcessTask& task) | |
6021 { | |
6022 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
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6023 FlexibleWorkGang* workers = gch->workers(); |
0 | 6024 assert(workers != NULL, "Need parallel worker threads."); |
6025 CMSRefProcTaskProxy rp_task(task, &_collector, | |
6026 _collector.ref_processor()->span(), | |
6027 _collector.markBitMap(), | |
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|
6028 workers, _collector.task_queues()); |
0 | 6029 workers->run_task(&rp_task); |
6030 } | |
6031 | |
6032 void CMSRefProcTaskExecutor::execute(EnqueueTask& task) | |
6033 { | |
6034 | |
6035 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
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6036 FlexibleWorkGang* workers = gch->workers(); |
0 | 6037 assert(workers != NULL, "Need parallel worker threads."); |
6038 CMSRefEnqueueTaskProxy enq_task(task); | |
6039 workers->run_task(&enq_task); | |
6040 } | |
6041 | |
6042 void CMSCollector::refProcessingWork(bool asynch, bool clear_all_soft_refs) { | |
6043 | |
6044 ResourceMark rm; | |
6045 HandleMark hm; | |
6046 | |
6047 ReferenceProcessor* rp = ref_processor(); | |
6048 assert(rp->span().equals(_span), "Spans should be equal"); | |
453
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6684579: SoftReference processing can be made more efficient
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|
6049 assert(!rp->enqueuing_is_done(), "Enqueuing should not be complete"); |
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6684579: SoftReference processing can be made more efficient
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452
diff
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|
6050 // Process weak references. |
457
27a80744a83b
6778647: snap(), snap_policy() should be renamed setup(), setup_policy()
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diff
changeset
|
6051 rp->setup_policy(clear_all_soft_refs); |
453
c96030fff130
6684579: SoftReference processing can be made more efficient
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|
6052 verify_work_stacks_empty(); |
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|
6053 |
0 | 6054 CMSKeepAliveClosure cmsKeepAliveClosure(this, _span, &_markBitMap, |
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|
6055 &_markStack, false /* !preclean */); |
0 | 6056 CMSDrainMarkingStackClosure cmsDrainMarkingStackClosure(this, |
6057 _span, &_markBitMap, &_markStack, | |
452
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
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diff
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|
6058 &cmsKeepAliveClosure, false /* !preclean */); |
0 | 6059 { |
10405 | 6060 GCTraceTime t("weak refs processing", PrintGCDetails, false, _gc_timer_cm); |
6061 | |
6062 ReferenceProcessorStats stats; | |
0 | 6063 if (rp->processing_is_mt()) { |
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|
6064 // Set the degree of MT here. If the discovery is done MT, there |
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diff
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|
6065 // may have been a different number of threads doing the discovery |
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changeset
|
6066 // and a different number of discovered lists may have Ref objects. |
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|
6067 // That is OK as long as the Reference lists are balanced (see |
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|
6068 // balance_all_queues() and balance_queues()). |
4095
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|
6069 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
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|
6070 int active_workers = ParallelGCThreads; |
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|
6071 FlexibleWorkGang* workers = gch->workers(); |
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|
6072 if (workers != NULL) { |
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|
6073 active_workers = workers->active_workers(); |
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|
6074 // The expectation is that active_workers will have already |
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|
6075 // been set to a reasonable value. If it has not been set, |
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diff
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|
6076 // investigate. |
bca17e38de00
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|
6077 assert(active_workers > 0, "Should have been set during scavenge"); |
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|
6078 } |
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diff
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|
6079 rp->set_active_mt_degree(active_workers); |
0 | 6080 CMSRefProcTaskExecutor task_executor(*this); |
10405 | 6081 stats = rp->process_discovered_references(&_is_alive_closure, |
0 | 6082 &cmsKeepAliveClosure, |
6083 &cmsDrainMarkingStackClosure, | |
10405 | 6084 &task_executor, |
6085 _gc_timer_cm); | |
0 | 6086 } else { |
10405 | 6087 stats = rp->process_discovered_references(&_is_alive_closure, |
0 | 6088 &cmsKeepAliveClosure, |
6089 &cmsDrainMarkingStackClosure, | |
10405 | 6090 NULL, |
6091 _gc_timer_cm); | |
6092 } | |
6093 _gc_tracer_cm->report_gc_reference_stats(stats); | |
6094 | |
10188
2f50bc369470
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diff
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|
6095 } |
2f50bc369470
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|
6096 |
2f50bc369470
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|
6097 // This is the point where the entire marking should have completed. |
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diff
changeset
|
6098 verify_work_stacks_empty(); |
0 | 6099 |
94
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6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
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6100 if (should_unload_classes()) { |
0 | 6101 { |
10405 | 6102 GCTraceTime t("class unloading", PrintGCDetails, false, _gc_timer_cm); |
0 | 6103 |
10188
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|
6104 // Unload classes and purge the SystemDictionary. |
0 | 6105 bool purged_class = SystemDictionary::do_unloading(&_is_alive_closure); |
6106 | |
10188
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changeset
|
6107 // Unload nmethods. |
6787
8966c2d65d96
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brutisso
parents:
6755
diff
changeset
|
6108 CodeCache::do_unloading(&_is_alive_closure, purged_class); |
0 | 6109 |
10188
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|
6110 // Prune dead klasses from subklass/sibling/implementor lists. |
6725
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|
6111 Klass::clean_weak_klass_links(&_is_alive_closure); |
0 | 6112 } |
6113 | |
6114 { | |
10405 | 6115 GCTraceTime t("scrub symbol table", PrintGCDetails, false, _gc_timer_cm); |
2177
3582bf76420e
6990754: Use native memory and reference counting to implement SymbolTable
coleenp
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|
6116 // Clean up unreferenced symbols in symbol table. |
3582bf76420e
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|
6117 SymbolTable::unlink(); |
0 | 6118 } |
6119 } | |
6120 | |
6725
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6121 // CMS doesn't use the StringTable as hard roots when class unloading is turned off. |
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|
6122 // Need to check if we really scanned the StringTable. |
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6123 if ((roots_scanning_options() & SharedHeap::SO_Strings) == 0) { |
10405 | 6124 GCTraceTime t("scrub string table", PrintGCDetails, false, _gc_timer_cm); |
10188
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6125 // Delete entries for dead interned strings. |
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6126 StringTable::unlink(&_is_alive_closure); |
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6127 } |
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6128 |
0 | 6129 // Restore any preserved marks as a result of mark stack or |
6130 // work queue overflow | |
6131 restore_preserved_marks_if_any(); // done single-threaded for now | |
6132 | |
6133 rp->set_enqueuing_is_done(true); | |
6134 if (rp->processing_is_mt()) { | |
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6135 rp->balance_all_queues(); |
0 | 6136 CMSRefProcTaskExecutor task_executor(*this); |
6137 rp->enqueue_discovered_references(&task_executor); | |
6138 } else { | |
6139 rp->enqueue_discovered_references(NULL); | |
6140 } | |
6141 rp->verify_no_references_recorded(); | |
6142 assert(!rp->discovery_enabled(), "should have been disabled"); | |
6143 } | |
6144 | |
6145 #ifndef PRODUCT | |
6146 void CMSCollector::check_correct_thread_executing() { | |
6147 Thread* t = Thread::current(); | |
6148 // Only the VM thread or the CMS thread should be here. | |
6149 assert(t->is_ConcurrentGC_thread() || t->is_VM_thread(), | |
6150 "Unexpected thread type"); | |
6151 // If this is the vm thread, the foreground process | |
6152 // should not be waiting. Note that _foregroundGCIsActive is | |
6153 // true while the foreground collector is waiting. | |
6154 if (_foregroundGCShouldWait) { | |
6155 // We cannot be the VM thread | |
6156 assert(t->is_ConcurrentGC_thread(), | |
6157 "Should be CMS thread"); | |
6158 } else { | |
6159 // We can be the CMS thread only if we are in a stop-world | |
6160 // phase of CMS collection. | |
6161 if (t->is_ConcurrentGC_thread()) { | |
6162 assert(_collectorState == InitialMarking || | |
6163 _collectorState == FinalMarking, | |
6164 "Should be a stop-world phase"); | |
6165 // The CMS thread should be holding the CMS_token. | |
6166 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
6167 "Potential interference with concurrently " | |
6168 "executing VM thread"); | |
6169 } | |
6170 } | |
6171 } | |
6172 #endif | |
6173 | |
6174 void CMSCollector::sweep(bool asynch) { | |
6175 assert(_collectorState == Sweeping, "just checking"); | |
6176 check_correct_thread_executing(); | |
6177 verify_work_stacks_empty(); | |
6178 verify_overflow_empty(); | |
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6179 increment_sweep_count(); |
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6180 TraceCMSMemoryManagerStats tms(_collectorState,GenCollectedHeap::heap()->gc_cause()); |
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6181 |
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6182 _inter_sweep_timer.stop(); |
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6183 _inter_sweep_estimate.sample(_inter_sweep_timer.seconds()); |
0 | 6184 size_policy()->avg_cms_free_at_sweep()->sample(_cmsGen->free()); |
6185 | |
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6186 assert(!_intra_sweep_timer.is_active(), "Should not be active"); |
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6187 _intra_sweep_timer.reset(); |
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6188 _intra_sweep_timer.start(); |
0 | 6189 if (asynch) { |
6190 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
6191 CMSPhaseAccounting pa(this, "sweep", !PrintGCDetails); | |
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6192 // First sweep the old gen |
0 | 6193 { |
6194 CMSTokenSyncWithLocks ts(true, _cmsGen->freelistLock(), | |
6195 bitMapLock()); | |
6196 sweepWork(_cmsGen, asynch); | |
6197 } | |
6198 | |
6199 // Update Universe::_heap_*_at_gc figures. | |
6200 // We need all the free list locks to make the abstract state | |
6201 // transition from Sweeping to Resetting. See detailed note | |
6202 // further below. | |
6203 { | |
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6204 CMSTokenSyncWithLocks ts(true, _cmsGen->freelistLock()); |
0 | 6205 // Update heap occupancy information which is used as |
6206 // input to soft ref clearing policy at the next gc. | |
6207 Universe::update_heap_info_at_gc(); | |
6208 _collectorState = Resizing; | |
6209 } | |
6210 } else { | |
6211 // already have needed locks | |
6212 sweepWork(_cmsGen, asynch); | |
6213 // Update heap occupancy information which is used as | |
6214 // input to soft ref clearing policy at the next gc. | |
6215 Universe::update_heap_info_at_gc(); | |
6216 _collectorState = Resizing; | |
6217 } | |
6218 verify_work_stacks_empty(); | |
6219 verify_overflow_empty(); | |
6220 | |
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6221 if (should_unload_classes()) { |
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6222 ClassLoaderDataGraph::purge(); |
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6223 } |
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6224 |
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6225 _intra_sweep_timer.stop(); |
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6226 _intra_sweep_estimate.sample(_intra_sweep_timer.seconds()); |
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6227 |
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6228 _inter_sweep_timer.reset(); |
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6229 _inter_sweep_timer.start(); |
0 | 6230 |
4911 | 6231 // We need to use a monotonically non-deccreasing time in ms |
6232 // or we will see time-warp warnings and os::javaTimeMillis() | |
6233 // does not guarantee monotonicity. | |
6234 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; | |
6235 update_time_of_last_gc(now); | |
0 | 6236 |
6237 // NOTE on abstract state transitions: | |
6238 // Mutators allocate-live and/or mark the mod-union table dirty | |
6239 // based on the state of the collection. The former is done in | |
6240 // the interval [Marking, Sweeping] and the latter in the interval | |
6241 // [Marking, Sweeping). Thus the transitions into the Marking state | |
6242 // and out of the Sweeping state must be synchronously visible | |
6243 // globally to the mutators. | |
6244 // The transition into the Marking state happens with the world | |
6245 // stopped so the mutators will globally see it. Sweeping is | |
6246 // done asynchronously by the background collector so the transition | |
6247 // from the Sweeping state to the Resizing state must be done | |
6248 // under the freelistLock (as is the check for whether to | |
6249 // allocate-live and whether to dirty the mod-union table). | |
6250 assert(_collectorState == Resizing, "Change of collector state to" | |
6251 " Resizing must be done under the freelistLocks (plural)"); | |
6252 | |
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6253 // Now that sweeping has been completed, we clear |
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6254 // the incremental_collection_failed flag, |
0 | 6255 // thus inviting a younger gen collection to promote into |
6256 // this generation. If such a promotion may still fail, | |
6257 // the flag will be set again when a young collection is | |
6258 // attempted. | |
6259 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
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6260 gch->clear_incremental_collection_failed(); // Worth retrying as fresh space may have been freed up |
0 | 6261 gch->update_full_collections_completed(_collection_count_start); |
6262 } | |
6263 | |
6264 // FIX ME!!! Looks like this belongs in CFLSpace, with | |
6265 // CMSGen merely delegating to it. | |
6266 void ConcurrentMarkSweepGeneration::setNearLargestChunk() { | |
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6267 double nearLargestPercent = FLSLargestBlockCoalesceProximity; |
0 | 6268 HeapWord* minAddr = _cmsSpace->bottom(); |
6269 HeapWord* largestAddr = | |
6028
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6270 (HeapWord*) _cmsSpace->dictionary()->find_largest_dict(); |
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6271 if (largestAddr == NULL) { |
0 | 6272 // The dictionary appears to be empty. In this case |
6273 // try to coalesce at the end of the heap. | |
6274 largestAddr = _cmsSpace->end(); | |
6275 } | |
6276 size_t largestOffset = pointer_delta(largestAddr, minAddr); | |
6277 size_t nearLargestOffset = | |
6278 (size_t)((double)largestOffset * nearLargestPercent) - MinChunkSize; | |
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6279 if (PrintFLSStatistics != 0) { |
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6280 gclog_or_tty->print_cr( |
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6281 "CMS: Large Block: " PTR_FORMAT ";" |
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6282 " Proximity: " PTR_FORMAT " -> " PTR_FORMAT, |
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6283 largestAddr, |
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6284 _cmsSpace->nearLargestChunk(), minAddr + nearLargestOffset); |
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6285 } |
0 | 6286 _cmsSpace->set_nearLargestChunk(minAddr + nearLargestOffset); |
6287 } | |
6288 | |
6289 bool ConcurrentMarkSweepGeneration::isNearLargestChunk(HeapWord* addr) { | |
6290 return addr >= _cmsSpace->nearLargestChunk(); | |
6291 } | |
6292 | |
6293 FreeChunk* ConcurrentMarkSweepGeneration::find_chunk_at_end() { | |
6294 return _cmsSpace->find_chunk_at_end(); | |
6295 } | |
6296 | |
6297 void ConcurrentMarkSweepGeneration::update_gc_stats(int current_level, | |
6298 bool full) { | |
6299 // The next lower level has been collected. Gather any statistics | |
6300 // that are of interest at this point. | |
6301 if (!full && (current_level + 1) == level()) { | |
6302 // Gather statistics on the young generation collection. | |
6303 collector()->stats().record_gc0_end(used()); | |
6304 } | |
6305 } | |
6306 | |
6307 CMSAdaptiveSizePolicy* ConcurrentMarkSweepGeneration::size_policy() { | |
6308 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
6309 assert(gch->kind() == CollectedHeap::GenCollectedHeap, | |
6310 "Wrong type of heap"); | |
6311 CMSAdaptiveSizePolicy* sp = (CMSAdaptiveSizePolicy*) | |
6312 gch->gen_policy()->size_policy(); | |
6313 assert(sp->is_gc_cms_adaptive_size_policy(), | |
6314 "Wrong type of size policy"); | |
6315 return sp; | |
6316 } | |
6317 | |
6318 void ConcurrentMarkSweepGeneration::rotate_debug_collection_type() { | |
6319 if (PrintGCDetails && Verbose) { | |
6320 gclog_or_tty->print("Rotate from %d ", _debug_collection_type); | |
6321 } | |
6322 _debug_collection_type = (CollectionTypes) (_debug_collection_type + 1); | |
6323 _debug_collection_type = | |
6324 (CollectionTypes) (_debug_collection_type % Unknown_collection_type); | |
6325 if (PrintGCDetails && Verbose) { | |
6326 gclog_or_tty->print_cr("to %d ", _debug_collection_type); | |
6327 } | |
6328 } | |
6329 | |
6330 void CMSCollector::sweepWork(ConcurrentMarkSweepGeneration* gen, | |
6331 bool asynch) { | |
6332 // We iterate over the space(s) underlying this generation, | |
6333 // checking the mark bit map to see if the bits corresponding | |
6334 // to specific blocks are marked or not. Blocks that are | |
6335 // marked are live and are not swept up. All remaining blocks | |
6336 // are swept up, with coalescing on-the-fly as we sweep up | |
6337 // contiguous free and/or garbage blocks: | |
6338 // We need to ensure that the sweeper synchronizes with allocators | |
6339 // and stop-the-world collectors. In particular, the following | |
6340 // locks are used: | |
6341 // . CMS token: if this is held, a stop the world collection cannot occur | |
6342 // . freelistLock: if this is held no allocation can occur from this | |
6343 // generation by another thread | |
6344 // . bitMapLock: if this is held, no other thread can access or update | |
6345 // | |
6346 | |
6347 // Note that we need to hold the freelistLock if we use | |
6348 // block iterate below; else the iterator might go awry if | |
6349 // a mutator (or promotion) causes block contents to change | |
6350 // (for instance if the allocator divvies up a block). | |
6351 // If we hold the free list lock, for all practical purposes | |
6352 // young generation GC's can't occur (they'll usually need to | |
6353 // promote), so we might as well prevent all young generation | |
6354 // GC's while we do a sweeping step. For the same reason, we might | |
6355 // as well take the bit map lock for the entire duration | |
6356 | |
6357 // check that we hold the requisite locks | |
6358 assert(have_cms_token(), "Should hold cms token"); | |
6359 assert( (asynch && ConcurrentMarkSweepThread::cms_thread_has_cms_token()) | |
6360 || (!asynch && ConcurrentMarkSweepThread::vm_thread_has_cms_token()), | |
6361 "Should possess CMS token to sweep"); | |
6362 assert_lock_strong(gen->freelistLock()); | |
6363 assert_lock_strong(bitMapLock()); | |
6364 | |
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6365 assert(!_inter_sweep_timer.is_active(), "Was switched off in an outer context"); |
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6366 assert(_intra_sweep_timer.is_active(), "Was switched on in an outer context"); |
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6367 gen->cmsSpace()->beginSweepFLCensus((float)(_inter_sweep_timer.seconds()), |
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6368 _inter_sweep_estimate.padded_average(), |
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6369 _intra_sweep_estimate.padded_average()); |
0 | 6370 gen->setNearLargestChunk(); |
6371 | |
6372 { | |
6373 SweepClosure sweepClosure(this, gen, &_markBitMap, | |
6374 CMSYield && asynch); | |
6375 gen->cmsSpace()->blk_iterate_careful(&sweepClosure); | |
6376 // We need to free-up/coalesce garbage/blocks from a | |
6377 // co-terminal free run. This is done in the SweepClosure | |
6378 // destructor; so, do not remove this scope, else the | |
6379 // end-of-sweep-census below will be off by a little bit. | |
6380 } | |
6381 gen->cmsSpace()->sweep_completed(); | |
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6382 gen->cmsSpace()->endSweepFLCensus(sweep_count()); |
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6383 if (should_unload_classes()) { // unloaded classes this cycle, |
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6384 _concurrent_cycles_since_last_unload = 0; // ... reset count |
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6385 } else { // did not unload classes, |
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6386 _concurrent_cycles_since_last_unload++; // ... increment count |
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6387 } |
0 | 6388 } |
6389 | |
6390 // Reset CMS data structures (for now just the marking bit map) | |
6391 // preparatory for the next cycle. | |
6392 void CMSCollector::reset(bool asynch) { | |
6393 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
6394 CMSAdaptiveSizePolicy* sp = size_policy(); | |
6395 AdaptiveSizePolicyOutput(sp, gch->total_collections()); | |
6396 if (asynch) { | |
6397 CMSTokenSyncWithLocks ts(true, bitMapLock()); | |
6398 | |
6399 // If the state is not "Resetting", the foreground thread | |
6400 // has done a collection and the resetting. | |
6401 if (_collectorState != Resetting) { | |
6402 assert(_collectorState == Idling, "The state should only change" | |
6403 " because the foreground collector has finished the collection"); | |
6404 return; | |
6405 } | |
6406 | |
6407 // Clear the mark bitmap (no grey objects to start with) | |
6408 // for the next cycle. | |
6409 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
6410 CMSPhaseAccounting cmspa(this, "reset", !PrintGCDetails); | |
6411 | |
6412 HeapWord* curAddr = _markBitMap.startWord(); | |
6413 while (curAddr < _markBitMap.endWord()) { | |
6414 size_t remaining = pointer_delta(_markBitMap.endWord(), curAddr); | |
6415 MemRegion chunk(curAddr, MIN2(CMSBitMapYieldQuantum, remaining)); | |
6416 _markBitMap.clear_large_range(chunk); | |
6417 if (ConcurrentMarkSweepThread::should_yield() && | |
6418 !foregroundGCIsActive() && | |
6419 CMSYield) { | |
6420 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
6421 "CMS thread should hold CMS token"); | |
6422 assert_lock_strong(bitMapLock()); | |
6423 bitMapLock()->unlock(); | |
6424 ConcurrentMarkSweepThread::desynchronize(true); | |
6425 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
6426 stopTimer(); | |
6427 if (PrintCMSStatistics != 0) { | |
6428 incrementYields(); | |
6429 } | |
6430 icms_wait(); | |
6431 | |
6432 // See the comment in coordinator_yield() | |
6433 for (unsigned i = 0; i < CMSYieldSleepCount && | |
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6434 ConcurrentMarkSweepThread::should_yield() && |
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6435 !CMSCollector::foregroundGCIsActive(); ++i) { |
0 | 6436 os::sleep(Thread::current(), 1, false); |
6437 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
6438 } | |
6439 | |
6440 ConcurrentMarkSweepThread::synchronize(true); | |
6441 bitMapLock()->lock_without_safepoint_check(); | |
6442 startTimer(); | |
6443 } | |
6444 curAddr = chunk.end(); | |
6445 } | |
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6446 // A successful mostly concurrent collection has been done. |
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6447 // Because only the full (i.e., concurrent mode failure) collections |
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6448 // are being measured for gc overhead limits, clean the "near" flag |
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6449 // and count. |
0bfd3fb24150
6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
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1289
diff
changeset
|
6450 sp->reset_gc_overhead_limit_count(); |
0 | 6451 _collectorState = Idling; |
6452 } else { | |
6453 // already have the lock | |
6454 assert(_collectorState == Resetting, "just checking"); | |
6455 assert_lock_strong(bitMapLock()); | |
6456 _markBitMap.clear_all(); | |
6457 _collectorState = Idling; | |
6458 } | |
6459 | |
6460 // Stop incremental mode after a cycle completes, so that any future cycles | |
6461 // are triggered by allocation. | |
6462 stop_icms(); | |
6463 | |
6464 NOT_PRODUCT( | |
6465 if (RotateCMSCollectionTypes) { | |
6466 _cmsGen->rotate_debug_collection_type(); | |
6467 } | |
6468 ) | |
10405 | 6469 |
6470 register_gc_end(); | |
0 | 6471 } |
6472 | |
6064
9d679effd28c
7166894: Add gc cause to GC logging for all collectors
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6028
diff
changeset
|
6473 void CMSCollector::do_CMS_operation(CMS_op_type op, GCCause::Cause gc_cause) { |
0 | 6474 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps); |
6475 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
10405 | 6476 GCTraceTime t(GCCauseString("GC", gc_cause), PrintGC, !PrintGCDetails, NULL); |
0 | 6477 TraceCollectorStats tcs(counters()); |
6478 | |
6479 switch (op) { | |
6480 case CMS_op_checkpointRootsInitial: { | |
2125
7246a374a9f2
6458402: 3 jvmti tests fail with CMS and +ExplicitGCInvokesConcurrent
kamg
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1994
diff
changeset
|
6481 SvcGCMarker sgcm(SvcGCMarker::OTHER); |
0 | 6482 checkpointRootsInitial(true); // asynch |
6483 if (PrintGC) { | |
6484 _cmsGen->printOccupancy("initial-mark"); | |
6485 } | |
6486 break; | |
6487 } | |
6488 case CMS_op_checkpointRootsFinal: { | |
2125
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diff
changeset
|
6489 SvcGCMarker sgcm(SvcGCMarker::OTHER); |
0 | 6490 checkpointRootsFinal(true, // asynch |
6491 false, // !clear_all_soft_refs | |
6492 false); // !init_mark_was_synchronous | |
6493 if (PrintGC) { | |
6494 _cmsGen->printOccupancy("remark"); | |
6495 } | |
6496 break; | |
6497 } | |
6498 default: | |
6499 fatal("No such CMS_op"); | |
6500 } | |
6501 } | |
6502 | |
6503 #ifndef PRODUCT | |
6504 size_t const CMSCollector::skip_header_HeapWords() { | |
6505 return FreeChunk::header_size(); | |
6506 } | |
6507 | |
6508 // Try and collect here conditions that should hold when | |
6509 // CMS thread is exiting. The idea is that the foreground GC | |
6510 // thread should not be blocked if it wants to terminate | |
6511 // the CMS thread and yet continue to run the VM for a while | |
6512 // after that. | |
6513 void CMSCollector::verify_ok_to_terminate() const { | |
6514 assert(Thread::current()->is_ConcurrentGC_thread(), | |
6515 "should be called by CMS thread"); | |
6516 assert(!_foregroundGCShouldWait, "should be false"); | |
6517 // We could check here that all the various low-level locks | |
6518 // are not held by the CMS thread, but that is overkill; see | |
6519 // also CMSThread::verify_ok_to_terminate() where the CGC_lock | |
6520 // is checked. | |
6521 } | |
6522 #endif | |
6523 | |
6524 size_t CMSCollector::block_size_using_printezis_bits(HeapWord* addr) const { | |
453
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diff
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|
6525 assert(_markBitMap.isMarked(addr) && _markBitMap.isMarked(addr + 1), |
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452
diff
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|
6526 "missing Printezis mark?"); |
0 | 6527 HeapWord* nextOneAddr = _markBitMap.getNextMarkedWordAddress(addr + 2); |
6528 size_t size = pointer_delta(nextOneAddr + 1, addr); | |
6529 assert(size == CompactibleFreeListSpace::adjustObjectSize(size), | |
6530 "alignment problem"); | |
6531 assert(size >= 3, "Necessary for Printezis marks to work"); | |
6532 return size; | |
6533 } | |
6534 | |
6535 // A variant of the above (block_size_using_printezis_bits()) except | |
6536 // that we return 0 if the P-bits are not yet set. | |
6537 size_t CMSCollector::block_size_if_printezis_bits(HeapWord* addr) const { | |
2226
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2177
diff
changeset
|
6538 if (_markBitMap.isMarked(addr + 1)) { |
c5a923563727
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2177
diff
changeset
|
6539 assert(_markBitMap.isMarked(addr), "P-bit can be set only for marked objects"); |
0 | 6540 HeapWord* nextOneAddr = _markBitMap.getNextMarkedWordAddress(addr + 2); |
6541 size_t size = pointer_delta(nextOneAddr + 1, addr); | |
6542 assert(size == CompactibleFreeListSpace::adjustObjectSize(size), | |
6543 "alignment problem"); | |
6544 assert(size >= 3, "Necessary for Printezis marks to work"); | |
6545 return size; | |
2226
c5a923563727
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diff
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|
6546 } |
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2177
diff
changeset
|
6547 return 0; |
0 | 6548 } |
6549 | |
6550 HeapWord* CMSCollector::next_card_start_after_block(HeapWord* addr) const { | |
6551 size_t sz = 0; | |
6552 oop p = (oop)addr; | |
6725
da91efe96a93
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|
6553 if (p->klass_or_null() != NULL) { |
0 | 6554 sz = CompactibleFreeListSpace::adjustObjectSize(p->size()); |
6555 } else { | |
6556 sz = block_size_using_printezis_bits(addr); | |
6557 } | |
6558 assert(sz > 0, "size must be nonzero"); | |
6559 HeapWord* next_block = addr + sz; | |
6560 HeapWord* next_card = (HeapWord*)round_to((uintptr_t)next_block, | |
6561 CardTableModRefBS::card_size); | |
6562 assert(round_down((uintptr_t)addr, CardTableModRefBS::card_size) < | |
6563 round_down((uintptr_t)next_card, CardTableModRefBS::card_size), | |
6564 "must be different cards"); | |
6565 return next_card; | |
6566 } | |
6567 | |
6568 | |
6569 // CMS Bit Map Wrapper ///////////////////////////////////////// | |
6570 | |
6571 // Construct a CMS bit map infrastructure, but don't create the | |
6572 // bit vector itself. That is done by a separate call CMSBitMap::allocate() | |
6573 // further below. | |
6574 CMSBitMap::CMSBitMap(int shifter, int mutex_rank, const char* mutex_name): | |
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|
6575 _bm(), |
0 | 6576 _shifter(shifter), |
6577 _lock(mutex_rank >= 0 ? new Mutex(mutex_rank, mutex_name, true) : NULL) | |
6578 { | |
6579 _bmStartWord = 0; | |
6580 _bmWordSize = 0; | |
6581 } | |
6582 | |
6583 bool CMSBitMap::allocate(MemRegion mr) { | |
6584 _bmStartWord = mr.start(); | |
6585 _bmWordSize = mr.word_size(); | |
6586 ReservedSpace brs(ReservedSpace::allocation_align_size_up( | |
6587 (_bmWordSize >> (_shifter + LogBitsPerByte)) + 1)); | |
6588 if (!brs.is_reserved()) { | |
6589 warning("CMS bit map allocation failure"); | |
6590 return false; | |
6591 } | |
6592 // For now we'll just commit all of the bit map up fromt. | |
6593 // Later on we'll try to be more parsimonious with swap. | |
6594 if (!_virtual_space.initialize(brs, brs.size())) { | |
6595 warning("CMS bit map backing store failure"); | |
6596 return false; | |
6597 } | |
6598 assert(_virtual_space.committed_size() == brs.size(), | |
6599 "didn't reserve backing store for all of CMS bit map?"); | |
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|
6600 _bm.set_map((BitMap::bm_word_t*)_virtual_space.low()); |
0 | 6601 assert(_virtual_space.committed_size() << (_shifter + LogBitsPerByte) >= |
6602 _bmWordSize, "inconsistency in bit map sizing"); | |
6603 _bm.set_size(_bmWordSize >> _shifter); | |
6604 | |
6605 // bm.clear(); // can we rely on getting zero'd memory? verify below | |
6606 assert(isAllClear(), | |
6607 "Expected zero'd memory from ReservedSpace constructor"); | |
6608 assert(_bm.size() == heapWordDiffToOffsetDiff(sizeInWords()), | |
6609 "consistency check"); | |
6610 return true; | |
6611 } | |
6612 | |
6613 void CMSBitMap::dirty_range_iterate_clear(MemRegion mr, MemRegionClosure* cl) { | |
6614 HeapWord *next_addr, *end_addr, *last_addr; | |
6615 assert_locked(); | |
6616 assert(covers(mr), "out-of-range error"); | |
6617 // XXX assert that start and end are appropriately aligned | |
6618 for (next_addr = mr.start(), end_addr = mr.end(); | |
6619 next_addr < end_addr; next_addr = last_addr) { | |
6620 MemRegion dirty_region = getAndClearMarkedRegion(next_addr, end_addr); | |
6621 last_addr = dirty_region.end(); | |
6622 if (!dirty_region.is_empty()) { | |
6623 cl->do_MemRegion(dirty_region); | |
6624 } else { | |
6625 assert(last_addr == end_addr, "program logic"); | |
6626 return; | |
6627 } | |
6628 } | |
6629 } | |
6630 | |
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7b835924c31c
8011872: Include Bit Map addresses in the hs_err files
stefank
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9072
diff
changeset
|
6631 void CMSBitMap::print_on_error(outputStream* st, const char* prefix) const { |
7b835924c31c
8011872: Include Bit Map addresses in the hs_err files
stefank
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9072
diff
changeset
|
6632 _bm.print_on_error(st, prefix); |
7b835924c31c
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9072
diff
changeset
|
6633 } |
7b835924c31c
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|
6634 |
0 | 6635 #ifndef PRODUCT |
6636 void CMSBitMap::assert_locked() const { | |
6637 CMSLockVerifier::assert_locked(lock()); | |
6638 } | |
6639 | |
6640 bool CMSBitMap::covers(MemRegion mr) const { | |
6641 // assert(_bm.map() == _virtual_space.low(), "map inconsistency"); | |
6642 assert((size_t)_bm.size() == (_bmWordSize >> _shifter), | |
6643 "size inconsistency"); | |
6644 return (mr.start() >= _bmStartWord) && | |
6645 (mr.end() <= endWord()); | |
6646 } | |
6647 | |
6648 bool CMSBitMap::covers(HeapWord* start, size_t size) const { | |
6649 return (start >= _bmStartWord && (start + size) <= endWord()); | |
6650 } | |
6651 | |
6652 void CMSBitMap::verifyNoOneBitsInRange(HeapWord* left, HeapWord* right) { | |
6653 // verify that there are no 1 bits in the interval [left, right) | |
6654 FalseBitMapClosure falseBitMapClosure; | |
6655 iterate(&falseBitMapClosure, left, right); | |
6656 } | |
6657 | |
6658 void CMSBitMap::region_invariant(MemRegion mr) | |
6659 { | |
6660 assert_locked(); | |
6661 // mr = mr.intersection(MemRegion(_bmStartWord, _bmWordSize)); | |
6662 assert(!mr.is_empty(), "unexpected empty region"); | |
6663 assert(covers(mr), "mr should be covered by bit map"); | |
6664 // convert address range into offset range | |
6665 size_t start_ofs = heapWordToOffset(mr.start()); | |
6666 // Make sure that end() is appropriately aligned | |
6667 assert(mr.end() == (HeapWord*)round_to((intptr_t)mr.end(), | |
6668 (1 << (_shifter+LogHeapWordSize))), | |
6669 "Misaligned mr.end()"); | |
6670 size_t end_ofs = heapWordToOffset(mr.end()); | |
6671 assert(end_ofs > start_ofs, "Should mark at least one bit"); | |
6672 } | |
6673 | |
6674 #endif | |
6675 | |
6676 bool CMSMarkStack::allocate(size_t size) { | |
6677 // allocate a stack of the requisite depth | |
6678 ReservedSpace rs(ReservedSpace::allocation_align_size_up( | |
6679 size * sizeof(oop))); | |
6680 if (!rs.is_reserved()) { | |
6681 warning("CMSMarkStack allocation failure"); | |
6682 return false; | |
6683 } | |
6684 if (!_virtual_space.initialize(rs, rs.size())) { | |
6685 warning("CMSMarkStack backing store failure"); | |
6686 return false; | |
6687 } | |
6688 assert(_virtual_space.committed_size() == rs.size(), | |
6689 "didn't reserve backing store for all of CMS stack?"); | |
6690 _base = (oop*)(_virtual_space.low()); | |
6691 _index = 0; | |
6692 _capacity = size; | |
6693 NOT_PRODUCT(_max_depth = 0); | |
6694 return true; | |
6695 } | |
6696 | |
6697 // XXX FIX ME !!! In the MT case we come in here holding a | |
6698 // leaf lock. For printing we need to take a further lock | |
6699 // which has lower rank. We need to recallibrate the two | |
6700 // lock-ranks involved in order to be able to rpint the | |
6701 // messages below. (Or defer the printing to the caller. | |
6702 // For now we take the expedient path of just disabling the | |
6703 // messages for the problematic case.) | |
6704 void CMSMarkStack::expand() { | |
1284 | 6705 assert(_capacity <= MarkStackSizeMax, "stack bigger than permitted"); |
6706 if (_capacity == MarkStackSizeMax) { | |
0 | 6707 if (_hit_limit++ == 0 && !CMSConcurrentMTEnabled && PrintGCDetails) { |
6708 // We print a warning message only once per CMS cycle. | |
6709 gclog_or_tty->print_cr(" (benign) Hit CMSMarkStack max size limit"); | |
6710 } | |
6711 return; | |
6712 } | |
6713 // Double capacity if possible | |
1284 | 6714 size_t new_capacity = MIN2(_capacity*2, MarkStackSizeMax); |
0 | 6715 // Do not give up existing stack until we have managed to |
6716 // get the double capacity that we desired. | |
6717 ReservedSpace rs(ReservedSpace::allocation_align_size_up( | |
6718 new_capacity * sizeof(oop))); | |
6719 if (rs.is_reserved()) { | |
6720 // Release the backing store associated with old stack | |
6721 _virtual_space.release(); | |
6722 // Reinitialize virtual space for new stack | |
6723 if (!_virtual_space.initialize(rs, rs.size())) { | |
6724 fatal("Not enough swap for expanded marking stack"); | |
6725 } | |
6726 _base = (oop*)(_virtual_space.low()); | |
6727 _index = 0; | |
6728 _capacity = new_capacity; | |
6729 } else if (_failed_double++ == 0 && !CMSConcurrentMTEnabled && PrintGCDetails) { | |
6730 // Failed to double capacity, continue; | |
6731 // we print a detail message only once per CMS cycle. | |
6732 gclog_or_tty->print(" (benign) Failed to expand marking stack from "SIZE_FORMAT"K to " | |
6733 SIZE_FORMAT"K", | |
6734 _capacity / K, new_capacity / K); | |
6735 } | |
6736 } | |
6737 | |
6738 | |
6739 // Closures | |
6740 // XXX: there seems to be a lot of code duplication here; | |
6741 // should refactor and consolidate common code. | |
6742 | |
6743 // This closure is used to mark refs into the CMS generation in | |
6744 // the CMS bit map. Called at the first checkpoint. This closure | |
6745 // assumes that we do not need to re-mark dirty cards; if the CMS | |
6725
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6197
diff
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|
6746 // generation on which this is used is not an oldest |
0 | 6747 // generation then this will lose younger_gen cards! |
6748 | |
6749 MarkRefsIntoClosure::MarkRefsIntoClosure( | |
994
753cf9794df9
6885169: merge of 4957990 and 6863023 causes conflict on do_nmethods
jrose
parents:
993
diff
changeset
|
6750 MemRegion span, CMSBitMap* bitMap): |
0 | 6751 _span(span), |
994
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6885169: merge of 4957990 and 6863023 causes conflict on do_nmethods
jrose
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993
diff
changeset
|
6752 _bitMap(bitMap) |
0 | 6753 { |
6754 assert(_ref_processor == NULL, "deliberately left NULL"); | |
6755 assert(_bitMap->covers(_span), "_bitMap/_span mismatch"); | |
6756 } | |
6757 | |
113
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diff
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|
6758 void MarkRefsIntoClosure::do_oop(oop obj) { |
0 | 6759 // if p points into _span, then mark corresponding bit in _markBitMap |
113
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6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
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diff
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|
6760 assert(obj->is_oop(), "expected an oop"); |
ba764ed4b6f2
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|
6761 HeapWord* addr = (HeapWord*)obj; |
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|
6762 if (_span.contains(addr)) { |
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diff
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|
6763 // this should be made more efficient |
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diff
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|
6764 _bitMap->mark(addr); |
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|
6765 } |
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|
6766 } |
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|
6767 |
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|
6768 void MarkRefsIntoClosure::do_oop(oop* p) { MarkRefsIntoClosure::do_oop_work(p); } |
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|
6769 void MarkRefsIntoClosure::do_oop(narrowOop* p) { MarkRefsIntoClosure::do_oop_work(p); } |
0 | 6770 |
6771 // A variant of the above, used for CMS marking verification. | |
6772 MarkRefsIntoVerifyClosure::MarkRefsIntoVerifyClosure( | |
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jrose
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|
6773 MemRegion span, CMSBitMap* verification_bm, CMSBitMap* cms_bm): |
0 | 6774 _span(span), |
6775 _verification_bm(verification_bm), | |
994
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diff
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|
6776 _cms_bm(cms_bm) |
753cf9794df9
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jrose
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diff
changeset
|
6777 { |
0 | 6778 assert(_ref_processor == NULL, "deliberately left NULL"); |
6779 assert(_verification_bm->covers(_span), "_verification_bm/_span mismatch"); | |
6780 } | |
6781 | |
113
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|
6782 void MarkRefsIntoVerifyClosure::do_oop(oop obj) { |
0 | 6783 // if p points into _span, then mark corresponding bit in _markBitMap |
113
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|
6784 assert(obj->is_oop(), "expected an oop"); |
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|
6785 HeapWord* addr = (HeapWord*)obj; |
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|
6786 if (_span.contains(addr)) { |
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|
6787 _verification_bm->mark(addr); |
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|
6788 if (!_cms_bm->isMarked(addr)) { |
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|
6789 oop(addr)->print(); |
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diff
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|
6790 gclog_or_tty->print_cr(" (" INTPTR_FORMAT " should have been marked)", addr); |
ba764ed4b6f2
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|
6791 fatal("... aborting"); |
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|
6792 } |
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|
6793 } |
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|
6794 } |
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6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
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|
6795 |
ba764ed4b6f2
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|
6796 void MarkRefsIntoVerifyClosure::do_oop(oop* p) { MarkRefsIntoVerifyClosure::do_oop_work(p); } |
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6797 void MarkRefsIntoVerifyClosure::do_oop(narrowOop* p) { MarkRefsIntoVerifyClosure::do_oop_work(p); } |
0 | 6798 |
6799 ////////////////////////////////////////////////// | |
6800 // MarkRefsIntoAndScanClosure | |
6801 ////////////////////////////////////////////////// | |
6802 | |
6803 MarkRefsIntoAndScanClosure::MarkRefsIntoAndScanClosure(MemRegion span, | |
6804 ReferenceProcessor* rp, | |
6805 CMSBitMap* bit_map, | |
6806 CMSBitMap* mod_union_table, | |
6807 CMSMarkStack* mark_stack, | |
6808 CMSCollector* collector, | |
6809 bool should_yield, | |
6810 bool concurrent_precleaning): | |
6811 _collector(collector), | |
6812 _span(span), | |
6813 _bit_map(bit_map), | |
6814 _mark_stack(mark_stack), | |
6815 _pushAndMarkClosure(collector, span, rp, bit_map, mod_union_table, | |
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6816 mark_stack, concurrent_precleaning), |
0 | 6817 _yield(should_yield), |
6818 _concurrent_precleaning(concurrent_precleaning), | |
6819 _freelistLock(NULL) | |
6820 { | |
6821 _ref_processor = rp; | |
6822 assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL"); | |
6823 } | |
6824 | |
6825 // This closure is used to mark refs into the CMS generation at the | |
6826 // second (final) checkpoint, and to scan and transitively follow | |
6827 // the unmarked oops. It is also used during the concurrent precleaning | |
6828 // phase while scanning objects on dirty cards in the CMS generation. | |
6829 // The marks are made in the marking bit map and the marking stack is | |
6830 // used for keeping the (newly) grey objects during the scan. | |
6831 // The parallel version (Par_...) appears further below. | |
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6832 void MarkRefsIntoAndScanClosure::do_oop(oop obj) { |
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6833 if (obj != NULL) { |
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6834 assert(obj->is_oop(), "expected an oop"); |
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6835 HeapWord* addr = (HeapWord*)obj; |
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6836 assert(_mark_stack->isEmpty(), "pre-condition (eager drainage)"); |
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6837 assert(_collector->overflow_list_is_empty(), |
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6838 "overflow list should be empty"); |
0 | 6839 if (_span.contains(addr) && |
6840 !_bit_map->isMarked(addr)) { | |
6841 // mark bit map (object is now grey) | |
6842 _bit_map->mark(addr); | |
6843 // push on marking stack (stack should be empty), and drain the | |
6844 // stack by applying this closure to the oops in the oops popped | |
6845 // from the stack (i.e. blacken the grey objects) | |
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6846 bool res = _mark_stack->push(obj); |
0 | 6847 assert(res, "Should have space to push on empty stack"); |
6848 do { | |
6849 oop new_oop = _mark_stack->pop(); | |
6850 assert(new_oop != NULL && new_oop->is_oop(), "Expected an oop"); | |
6851 assert(_bit_map->isMarked((HeapWord*)new_oop), | |
6852 "only grey objects on this stack"); | |
6853 // iterate over the oops in this oop, marking and pushing | |
6854 // the ones in CMS heap (i.e. in _span). | |
6855 new_oop->oop_iterate(&_pushAndMarkClosure); | |
6856 // check if it's time to yield | |
6857 do_yield_check(); | |
6858 } while (!_mark_stack->isEmpty() || | |
6859 (!_concurrent_precleaning && take_from_overflow_list())); | |
6860 // if marking stack is empty, and we are not doing this | |
6861 // during precleaning, then check the overflow list | |
6862 } | |
6863 assert(_mark_stack->isEmpty(), "post-condition (eager drainage)"); | |
6864 assert(_collector->overflow_list_is_empty(), | |
6865 "overflow list was drained above"); | |
6866 // We could restore evacuated mark words, if any, used for | |
6867 // overflow list links here because the overflow list is | |
6868 // provably empty here. That would reduce the maximum | |
6869 // size requirements for preserved_{oop,mark}_stack. | |
6870 // But we'll just postpone it until we are all done | |
6871 // so we can just stream through. | |
6872 if (!_concurrent_precleaning && CMSOverflowEarlyRestoration) { | |
6873 _collector->restore_preserved_marks_if_any(); | |
6874 assert(_collector->no_preserved_marks(), "No preserved marks"); | |
6875 } | |
6876 assert(!CMSOverflowEarlyRestoration || _collector->no_preserved_marks(), | |
6877 "All preserved marks should have been restored above"); | |
6878 } | |
6879 } | |
6880 | |
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6881 void MarkRefsIntoAndScanClosure::do_oop(oop* p) { MarkRefsIntoAndScanClosure::do_oop_work(p); } |
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6882 void MarkRefsIntoAndScanClosure::do_oop(narrowOop* p) { MarkRefsIntoAndScanClosure::do_oop_work(p); } |
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6883 |
0 | 6884 void MarkRefsIntoAndScanClosure::do_yield_work() { |
6885 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
6886 "CMS thread should hold CMS token"); | |
6887 assert_lock_strong(_freelistLock); | |
6888 assert_lock_strong(_bit_map->lock()); | |
6889 // relinquish the free_list_lock and bitMaplock() | |
6890 _bit_map->lock()->unlock(); | |
6891 _freelistLock->unlock(); | |
6892 ConcurrentMarkSweepThread::desynchronize(true); | |
6893 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
6894 _collector->stopTimer(); | |
6895 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
6896 if (PrintCMSStatistics != 0) { | |
6897 _collector->incrementYields(); | |
6898 } | |
6899 _collector->icms_wait(); | |
6900 | |
6901 // See the comment in coordinator_yield() | |
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6902 for (unsigned i = 0; |
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6903 i < CMSYieldSleepCount && |
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6904 ConcurrentMarkSweepThread::should_yield() && |
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6905 !CMSCollector::foregroundGCIsActive(); |
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6906 ++i) { |
0 | 6907 os::sleep(Thread::current(), 1, false); |
6908 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
6909 } | |
6910 | |
6911 ConcurrentMarkSweepThread::synchronize(true); | |
6912 _freelistLock->lock_without_safepoint_check(); | |
6913 _bit_map->lock()->lock_without_safepoint_check(); | |
6914 _collector->startTimer(); | |
6915 } | |
6916 | |
6917 /////////////////////////////////////////////////////////// | |
6918 // Par_MarkRefsIntoAndScanClosure: a parallel version of | |
6919 // MarkRefsIntoAndScanClosure | |
6920 /////////////////////////////////////////////////////////// | |
6921 Par_MarkRefsIntoAndScanClosure::Par_MarkRefsIntoAndScanClosure( | |
6922 CMSCollector* collector, MemRegion span, ReferenceProcessor* rp, | |
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6923 CMSBitMap* bit_map, OopTaskQueue* work_queue): |
0 | 6924 _span(span), |
6925 _bit_map(bit_map), | |
6926 _work_queue(work_queue), | |
6927 _low_water_mark(MIN2((uint)(work_queue->max_elems()/4), | |
6928 (uint)(CMSWorkQueueDrainThreshold * ParallelGCThreads))), | |
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6929 _par_pushAndMarkClosure(collector, span, rp, bit_map, work_queue) |
0 | 6930 { |
6931 _ref_processor = rp; | |
6932 assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL"); | |
6933 } | |
6934 | |
6935 // This closure is used to mark refs into the CMS generation at the | |
6936 // second (final) checkpoint, and to scan and transitively follow | |
6937 // the unmarked oops. The marks are made in the marking bit map and | |
6938 // the work_queue is used for keeping the (newly) grey objects during | |
6939 // the scan phase whence they are also available for stealing by parallel | |
6940 // threads. Since the marking bit map is shared, updates are | |
6941 // synchronized (via CAS). | |
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6942 void Par_MarkRefsIntoAndScanClosure::do_oop(oop obj) { |
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6943 if (obj != NULL) { |
0 | 6944 // Ignore mark word because this could be an already marked oop |
6945 // that may be chained at the end of the overflow list. | |
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6946 assert(obj->is_oop(true), "expected an oop"); |
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6947 HeapWord* addr = (HeapWord*)obj; |
0 | 6948 if (_span.contains(addr) && |
6949 !_bit_map->isMarked(addr)) { | |
6950 // mark bit map (object will become grey): | |
6951 // It is possible for several threads to be | |
6952 // trying to "claim" this object concurrently; | |
6953 // the unique thread that succeeds in marking the | |
6954 // object first will do the subsequent push on | |
6955 // to the work queue (or overflow list). | |
6956 if (_bit_map->par_mark(addr)) { | |
6957 // push on work_queue (which may not be empty), and trim the | |
6958 // queue to an appropriate length by applying this closure to | |
6959 // the oops in the oops popped from the stack (i.e. blacken the | |
6960 // grey objects) | |
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6961 bool res = _work_queue->push(obj); |
0 | 6962 assert(res, "Low water mark should be less than capacity?"); |
6963 trim_queue(_low_water_mark); | |
6964 } // Else, another thread claimed the object | |
6965 } | |
6966 } | |
6967 } | |
6968 | |
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6969 void Par_MarkRefsIntoAndScanClosure::do_oop(oop* p) { Par_MarkRefsIntoAndScanClosure::do_oop_work(p); } |
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6970 void Par_MarkRefsIntoAndScanClosure::do_oop(narrowOop* p) { Par_MarkRefsIntoAndScanClosure::do_oop_work(p); } |
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6971 |
0 | 6972 // This closure is used to rescan the marked objects on the dirty cards |
6973 // in the mod union table and the card table proper. | |
6974 size_t ScanMarkedObjectsAgainCarefullyClosure::do_object_careful_m( | |
6975 oop p, MemRegion mr) { | |
6976 | |
6977 size_t size = 0; | |
6978 HeapWord* addr = (HeapWord*)p; | |
6979 DEBUG_ONLY(_collector->verify_work_stacks_empty();) | |
6980 assert(_span.contains(addr), "we are scanning the CMS generation"); | |
6981 // check if it's time to yield | |
6982 if (do_yield_check()) { | |
6983 // We yielded for some foreground stop-world work, | |
6984 // and we have been asked to abort this ongoing preclean cycle. | |
6985 return 0; | |
6986 } | |
6987 if (_bitMap->isMarked(addr)) { | |
6988 // it's marked; is it potentially uninitialized? | |
187 | 6989 if (p->klass_or_null() != NULL) { |
0 | 6990 // an initialized object; ignore mark word in verification below |
6991 // since we are running concurrent with mutators | |
6992 assert(p->is_oop(true), "should be an oop"); | |
6993 if (p->is_objArray()) { | |
6994 // objArrays are precisely marked; restrict scanning | |
6995 // to dirty cards only. | |
187 | 6996 size = CompactibleFreeListSpace::adjustObjectSize( |
6997 p->oop_iterate(_scanningClosure, mr)); | |
0 | 6998 } else { |
6999 // A non-array may have been imprecisely marked; we need | |
7000 // to scan object in its entirety. | |
7001 size = CompactibleFreeListSpace::adjustObjectSize( | |
7002 p->oop_iterate(_scanningClosure)); | |
7003 } | |
9152 | 7004 #ifdef ASSERT |
0 | 7005 size_t direct_size = |
7006 CompactibleFreeListSpace::adjustObjectSize(p->size()); | |
7007 assert(size == direct_size, "Inconsistency in size"); | |
7008 assert(size >= 3, "Necessary for Printezis marks to work"); | |
7009 if (!_bitMap->isMarked(addr+1)) { | |
7010 _bitMap->verifyNoOneBitsInRange(addr+2, addr+size); | |
7011 } else { | |
7012 _bitMap->verifyNoOneBitsInRange(addr+2, addr+size-1); | |
7013 assert(_bitMap->isMarked(addr+size-1), | |
7014 "inconsistent Printezis mark"); | |
7015 } | |
9152 | 7016 #endif // ASSERT |
0 | 7017 } else { |
7018 // an unitialized object | |
7019 assert(_bitMap->isMarked(addr+1), "missing Printezis mark?"); | |
7020 HeapWord* nextOneAddr = _bitMap->getNextMarkedWordAddress(addr + 2); | |
7021 size = pointer_delta(nextOneAddr + 1, addr); | |
7022 assert(size == CompactibleFreeListSpace::adjustObjectSize(size), | |
7023 "alignment problem"); | |
7024 // Note that pre-cleaning needn't redirty the card. OopDesc::set_klass() | |
7025 // will dirty the card when the klass pointer is installed in the | |
7026 // object (signalling the completion of initialization). | |
7027 } | |
7028 } else { | |
7029 // Either a not yet marked object or an uninitialized object | |
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7030 if (p->klass_or_null() == NULL) { |
0 | 7031 // An uninitialized object, skip to the next card, since |
7032 // we may not be able to read its P-bits yet. | |
7033 assert(size == 0, "Initial value"); | |
7034 } else { | |
7035 // An object not (yet) reached by marking: we merely need to | |
7036 // compute its size so as to go look at the next block. | |
7037 assert(p->is_oop(true), "should be an oop"); | |
7038 size = CompactibleFreeListSpace::adjustObjectSize(p->size()); | |
7039 } | |
7040 } | |
7041 DEBUG_ONLY(_collector->verify_work_stacks_empty();) | |
7042 return size; | |
7043 } | |
7044 | |
7045 void ScanMarkedObjectsAgainCarefullyClosure::do_yield_work() { | |
7046 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
7047 "CMS thread should hold CMS token"); | |
7048 assert_lock_strong(_freelistLock); | |
7049 assert_lock_strong(_bitMap->lock()); | |
7050 // relinquish the free_list_lock and bitMaplock() | |
7051 _bitMap->lock()->unlock(); | |
7052 _freelistLock->unlock(); | |
7053 ConcurrentMarkSweepThread::desynchronize(true); | |
7054 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
7055 _collector->stopTimer(); | |
7056 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
7057 if (PrintCMSStatistics != 0) { | |
7058 _collector->incrementYields(); | |
7059 } | |
7060 _collector->icms_wait(); | |
7061 | |
7062 // See the comment in coordinator_yield() | |
7063 for (unsigned i = 0; i < CMSYieldSleepCount && | |
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7064 ConcurrentMarkSweepThread::should_yield() && |
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7065 !CMSCollector::foregroundGCIsActive(); ++i) { |
0 | 7066 os::sleep(Thread::current(), 1, false); |
7067 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
7068 } | |
7069 | |
7070 ConcurrentMarkSweepThread::synchronize(true); | |
7071 _freelistLock->lock_without_safepoint_check(); | |
7072 _bitMap->lock()->lock_without_safepoint_check(); | |
7073 _collector->startTimer(); | |
7074 } | |
7075 | |
7076 | |
7077 ////////////////////////////////////////////////////////////////// | |
7078 // SurvivorSpacePrecleanClosure | |
7079 ////////////////////////////////////////////////////////////////// | |
7080 // This (single-threaded) closure is used to preclean the oops in | |
7081 // the survivor spaces. | |
7082 size_t SurvivorSpacePrecleanClosure::do_object_careful(oop p) { | |
7083 | |
7084 HeapWord* addr = (HeapWord*)p; | |
7085 DEBUG_ONLY(_collector->verify_work_stacks_empty();) | |
7086 assert(!_span.contains(addr), "we are scanning the survivor spaces"); | |
187 | 7087 assert(p->klass_or_null() != NULL, "object should be initializd"); |
0 | 7088 // an initialized object; ignore mark word in verification below |
7089 // since we are running concurrent with mutators | |
7090 assert(p->is_oop(true), "should be an oop"); | |
7091 // Note that we do not yield while we iterate over | |
7092 // the interior oops of p, pushing the relevant ones | |
7093 // on our marking stack. | |
7094 size_t size = p->oop_iterate(_scanning_closure); | |
7095 do_yield_check(); | |
7096 // Observe that below, we do not abandon the preclean | |
7097 // phase as soon as we should; rather we empty the | |
7098 // marking stack before returning. This is to satisfy | |
7099 // some existing assertions. In general, it may be a | |
7100 // good idea to abort immediately and complete the marking | |
7101 // from the grey objects at a later time. | |
7102 while (!_mark_stack->isEmpty()) { | |
7103 oop new_oop = _mark_stack->pop(); | |
7104 assert(new_oop != NULL && new_oop->is_oop(), "Expected an oop"); | |
7105 assert(_bit_map->isMarked((HeapWord*)new_oop), | |
7106 "only grey objects on this stack"); | |
7107 // iterate over the oops in this oop, marking and pushing | |
7108 // the ones in CMS heap (i.e. in _span). | |
7109 new_oop->oop_iterate(_scanning_closure); | |
7110 // check if it's time to yield | |
7111 do_yield_check(); | |
7112 } | |
7113 unsigned int after_count = | |
7114 GenCollectedHeap::heap()->total_collections(); | |
7115 bool abort = (_before_count != after_count) || | |
7116 _collector->should_abort_preclean(); | |
7117 return abort ? 0 : size; | |
7118 } | |
7119 | |
7120 void SurvivorSpacePrecleanClosure::do_yield_work() { | |
7121 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
7122 "CMS thread should hold CMS token"); | |
7123 assert_lock_strong(_bit_map->lock()); | |
7124 // Relinquish the bit map lock | |
7125 _bit_map->lock()->unlock(); | |
7126 ConcurrentMarkSweepThread::desynchronize(true); | |
7127 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
7128 _collector->stopTimer(); | |
7129 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
7130 if (PrintCMSStatistics != 0) { | |
7131 _collector->incrementYields(); | |
7132 } | |
7133 _collector->icms_wait(); | |
7134 | |
7135 // See the comment in coordinator_yield() | |
7136 for (unsigned i = 0; i < CMSYieldSleepCount && | |
7137 ConcurrentMarkSweepThread::should_yield() && | |
7138 !CMSCollector::foregroundGCIsActive(); ++i) { | |
7139 os::sleep(Thread::current(), 1, false); | |
7140 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
7141 } | |
7142 | |
7143 ConcurrentMarkSweepThread::synchronize(true); | |
7144 _bit_map->lock()->lock_without_safepoint_check(); | |
7145 _collector->startTimer(); | |
7146 } | |
7147 | |
7148 // This closure is used to rescan the marked objects on the dirty cards | |
7149 // in the mod union table and the card table proper. In the parallel | |
7150 // case, although the bitMap is shared, we do a single read so the | |
7151 // isMarked() query is "safe". | |
7152 bool ScanMarkedObjectsAgainClosure::do_object_bm(oop p, MemRegion mr) { | |
7153 // Ignore mark word because we are running concurrent with mutators | |
7154 assert(p->is_oop_or_null(true), "expected an oop or null"); | |
7155 HeapWord* addr = (HeapWord*)p; | |
7156 assert(_span.contains(addr), "we are scanning the CMS generation"); | |
7157 bool is_obj_array = false; | |
9152 | 7158 #ifdef ASSERT |
0 | 7159 if (!_parallel) { |
7160 assert(_mark_stack->isEmpty(), "pre-condition (eager drainage)"); | |
7161 assert(_collector->overflow_list_is_empty(), | |
7162 "overflow list should be empty"); | |
7163 | |
7164 } | |
9152 | 7165 #endif // ASSERT |
0 | 7166 if (_bit_map->isMarked(addr)) { |
7167 // Obj arrays are precisely marked, non-arrays are not; | |
7168 // so we scan objArrays precisely and non-arrays in their | |
7169 // entirety. | |
7170 if (p->is_objArray()) { | |
7171 is_obj_array = true; | |
7172 if (_parallel) { | |
7173 p->oop_iterate(_par_scan_closure, mr); | |
7174 } else { | |
7175 p->oop_iterate(_scan_closure, mr); | |
7176 } | |
7177 } else { | |
7178 if (_parallel) { | |
7179 p->oop_iterate(_par_scan_closure); | |
7180 } else { | |
7181 p->oop_iterate(_scan_closure); | |
7182 } | |
7183 } | |
7184 } | |
9152 | 7185 #ifdef ASSERT |
0 | 7186 if (!_parallel) { |
7187 assert(_mark_stack->isEmpty(), "post-condition (eager drainage)"); | |
7188 assert(_collector->overflow_list_is_empty(), | |
7189 "overflow list should be empty"); | |
7190 | |
7191 } | |
9152 | 7192 #endif // ASSERT |
0 | 7193 return is_obj_array; |
7194 } | |
7195 | |
7196 MarkFromRootsClosure::MarkFromRootsClosure(CMSCollector* collector, | |
7197 MemRegion span, | |
7198 CMSBitMap* bitMap, CMSMarkStack* markStack, | |
7199 bool should_yield, bool verifying): | |
7200 _collector(collector), | |
7201 _span(span), | |
7202 _bitMap(bitMap), | |
7203 _mut(&collector->_modUnionTable), | |
7204 _markStack(markStack), | |
7205 _yield(should_yield), | |
7206 _skipBits(0) | |
7207 { | |
7208 assert(_markStack->isEmpty(), "stack should be empty"); | |
7209 _finger = _bitMap->startWord(); | |
7210 _threshold = _finger; | |
7211 assert(_collector->_restart_addr == NULL, "Sanity check"); | |
7212 assert(_span.contains(_finger), "Out of bounds _finger?"); | |
7213 DEBUG_ONLY(_verifying = verifying;) | |
7214 } | |
7215 | |
7216 void MarkFromRootsClosure::reset(HeapWord* addr) { | |
7217 assert(_markStack->isEmpty(), "would cause duplicates on stack"); | |
7218 assert(_span.contains(addr), "Out of bounds _finger?"); | |
7219 _finger = addr; | |
7220 _threshold = (HeapWord*)round_to( | |
7221 (intptr_t)_finger, CardTableModRefBS::card_size); | |
7222 } | |
7223 | |
7224 // Should revisit to see if this should be restructured for | |
7225 // greater efficiency. | |
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7226 bool MarkFromRootsClosure::do_bit(size_t offset) { |
0 | 7227 if (_skipBits > 0) { |
7228 _skipBits--; | |
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7229 return true; |
0 | 7230 } |
7231 // convert offset into a HeapWord* | |
7232 HeapWord* addr = _bitMap->startWord() + offset; | |
7233 assert(_bitMap->endWord() && addr < _bitMap->endWord(), | |
7234 "address out of range"); | |
7235 assert(_bitMap->isMarked(addr), "tautology"); | |
7236 if (_bitMap->isMarked(addr+1)) { | |
7237 // this is an allocated but not yet initialized object | |
7238 assert(_skipBits == 0, "tautology"); | |
7239 _skipBits = 2; // skip next two marked bits ("Printezis-marks") | |
7240 oop p = oop(addr); | |
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7241 if (p->klass_or_null() == NULL) { |
0 | 7242 DEBUG_ONLY(if (!_verifying) {) |
7243 // We re-dirty the cards on which this object lies and increase | |
7244 // the _threshold so that we'll come back to scan this object | |
7245 // during the preclean or remark phase. (CMSCleanOnEnter) | |
7246 if (CMSCleanOnEnter) { | |
7247 size_t sz = _collector->block_size_using_printezis_bits(addr); | |
7248 HeapWord* end_card_addr = (HeapWord*)round_to( | |
7249 (intptr_t)(addr+sz), CardTableModRefBS::card_size); | |
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7250 MemRegion redirty_range = MemRegion(addr, end_card_addr); |
0 | 7251 assert(!redirty_range.is_empty(), "Arithmetical tautology"); |
7252 // Bump _threshold to end_card_addr; note that | |
7253 // _threshold cannot possibly exceed end_card_addr, anyhow. | |
7254 // This prevents future clearing of the card as the scan proceeds | |
7255 // to the right. | |
7256 assert(_threshold <= end_card_addr, | |
7257 "Because we are just scanning into this object"); | |
7258 if (_threshold < end_card_addr) { | |
7259 _threshold = end_card_addr; | |
7260 } | |
187 | 7261 if (p->klass_or_null() != NULL) { |
0 | 7262 // Redirty the range of cards... |
7263 _mut->mark_range(redirty_range); | |
7264 } // ...else the setting of klass will dirty the card anyway. | |
7265 } | |
7266 DEBUG_ONLY(}) | |
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7267 return true; |
0 | 7268 } |
7269 } | |
7270 scanOopsInOop(addr); | |
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7271 return true; |
0 | 7272 } |
7273 | |
7274 // We take a break if we've been at this for a while, | |
7275 // so as to avoid monopolizing the locks involved. | |
7276 void MarkFromRootsClosure::do_yield_work() { | |
7277 // First give up the locks, then yield, then re-lock | |
7278 // We should probably use a constructor/destructor idiom to | |
7279 // do this unlock/lock or modify the MutexUnlocker class to | |
7280 // serve our purpose. XXX | |
7281 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
7282 "CMS thread should hold CMS token"); | |
7283 assert_lock_strong(_bitMap->lock()); | |
7284 _bitMap->lock()->unlock(); | |
7285 ConcurrentMarkSweepThread::desynchronize(true); | |
7286 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
7287 _collector->stopTimer(); | |
7288 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
7289 if (PrintCMSStatistics != 0) { | |
7290 _collector->incrementYields(); | |
7291 } | |
7292 _collector->icms_wait(); | |
7293 | |
7294 // See the comment in coordinator_yield() | |
7295 for (unsigned i = 0; i < CMSYieldSleepCount && | |
7296 ConcurrentMarkSweepThread::should_yield() && | |
7297 !CMSCollector::foregroundGCIsActive(); ++i) { | |
7298 os::sleep(Thread::current(), 1, false); | |
7299 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
7300 } | |
7301 | |
7302 ConcurrentMarkSweepThread::synchronize(true); | |
7303 _bitMap->lock()->lock_without_safepoint_check(); | |
7304 _collector->startTimer(); | |
7305 } | |
7306 | |
7307 void MarkFromRootsClosure::scanOopsInOop(HeapWord* ptr) { | |
7308 assert(_bitMap->isMarked(ptr), "expected bit to be set"); | |
7309 assert(_markStack->isEmpty(), | |
7310 "should drain stack to limit stack usage"); | |
7311 // convert ptr to an oop preparatory to scanning | |
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7312 oop obj = oop(ptr); |
0 | 7313 // Ignore mark word in verification below, since we |
7314 // may be running concurrent with mutators. | |
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7315 assert(obj->is_oop(true), "should be an oop"); |
0 | 7316 assert(_finger <= ptr, "_finger runneth ahead"); |
7317 // advance the finger to right end of this object | |
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7318 _finger = ptr + obj->size(); |
0 | 7319 assert(_finger > ptr, "we just incremented it above"); |
7320 // On large heaps, it may take us some time to get through | |
7321 // the marking phase (especially if running iCMS). During | |
7322 // this time it's possible that a lot of mutations have | |
7323 // accumulated in the card table and the mod union table -- | |
7324 // these mutation records are redundant until we have | |
7325 // actually traced into the corresponding card. | |
7326 // Here, we check whether advancing the finger would make | |
7327 // us cross into a new card, and if so clear corresponding | |
7328 // cards in the MUT (preclean them in the card-table in the | |
7329 // future). | |
7330 | |
7331 DEBUG_ONLY(if (!_verifying) {) | |
7332 // The clean-on-enter optimization is disabled by default, | |
7333 // until we fix 6178663. | |
7334 if (CMSCleanOnEnter && (_finger > _threshold)) { | |
7335 // [_threshold, _finger) represents the interval | |
7336 // of cards to be cleared in MUT (or precleaned in card table). | |
7337 // The set of cards to be cleared is all those that overlap | |
7338 // with the interval [_threshold, _finger); note that | |
7339 // _threshold is always kept card-aligned but _finger isn't | |
7340 // always card-aligned. | |
7341 HeapWord* old_threshold = _threshold; | |
7342 assert(old_threshold == (HeapWord*)round_to( | |
7343 (intptr_t)old_threshold, CardTableModRefBS::card_size), | |
7344 "_threshold should always be card-aligned"); | |
7345 _threshold = (HeapWord*)round_to( | |
7346 (intptr_t)_finger, CardTableModRefBS::card_size); | |
7347 MemRegion mr(old_threshold, _threshold); | |
7348 assert(!mr.is_empty(), "Control point invariant"); | |
7349 assert(_span.contains(mr), "Should clear within span"); | |
7350 _mut->clear_range(mr); | |
7351 } | |
7352 DEBUG_ONLY(}) | |
7353 // Note: the finger doesn't advance while we drain | |
7354 // the stack below. | |
7355 PushOrMarkClosure pushOrMarkClosure(_collector, | |
7356 _span, _bitMap, _markStack, | |
7357 _finger, this); | |
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7358 bool res = _markStack->push(obj); |
0 | 7359 assert(res, "Empty non-zero size stack should have space for single push"); |
7360 while (!_markStack->isEmpty()) { | |
7361 oop new_oop = _markStack->pop(); | |
7362 // Skip verifying header mark word below because we are | |
7363 // running concurrent with mutators. | |
7364 assert(new_oop->is_oop(true), "Oops! expected to pop an oop"); | |
7365 // now scan this oop's oops | |
7366 new_oop->oop_iterate(&pushOrMarkClosure); | |
7367 do_yield_check(); | |
7368 } | |
7369 assert(_markStack->isEmpty(), "tautology, emphasizing post-condition"); | |
7370 } | |
7371 | |
7372 Par_MarkFromRootsClosure::Par_MarkFromRootsClosure(CMSConcMarkingTask* task, | |
7373 CMSCollector* collector, MemRegion span, | |
7374 CMSBitMap* bit_map, | |
7375 OopTaskQueue* work_queue, | |
7376 CMSMarkStack* overflow_stack, | |
7377 bool should_yield): | |
7378 _collector(collector), | |
7379 _whole_span(collector->_span), | |
7380 _span(span), | |
7381 _bit_map(bit_map), | |
7382 _mut(&collector->_modUnionTable), | |
7383 _work_queue(work_queue), | |
7384 _overflow_stack(overflow_stack), | |
7385 _yield(should_yield), | |
7386 _skip_bits(0), | |
7387 _task(task) | |
7388 { | |
7389 assert(_work_queue->size() == 0, "work_queue should be empty"); | |
7390 _finger = span.start(); | |
7391 _threshold = _finger; // XXX Defer clear-on-enter optimization for now | |
7392 assert(_span.contains(_finger), "Out of bounds _finger?"); | |
7393 } | |
7394 | |
7395 // Should revisit to see if this should be restructured for | |
7396 // greater efficiency. | |
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7397 bool Par_MarkFromRootsClosure::do_bit(size_t offset) { |
0 | 7398 if (_skip_bits > 0) { |
7399 _skip_bits--; | |
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7400 return true; |
0 | 7401 } |
7402 // convert offset into a HeapWord* | |
7403 HeapWord* addr = _bit_map->startWord() + offset; | |
7404 assert(_bit_map->endWord() && addr < _bit_map->endWord(), | |
7405 "address out of range"); | |
7406 assert(_bit_map->isMarked(addr), "tautology"); | |
7407 if (_bit_map->isMarked(addr+1)) { | |
7408 // this is an allocated object that might not yet be initialized | |
7409 assert(_skip_bits == 0, "tautology"); | |
7410 _skip_bits = 2; // skip next two marked bits ("Printezis-marks") | |
7411 oop p = oop(addr); | |
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7412 if (p->klass_or_null() == NULL) { |
0 | 7413 // in the case of Clean-on-Enter optimization, redirty card |
7414 // and avoid clearing card by increasing the threshold. | |
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7415 return true; |
0 | 7416 } |
7417 } | |
7418 scan_oops_in_oop(addr); | |
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7419 return true; |
0 | 7420 } |
7421 | |
7422 void Par_MarkFromRootsClosure::scan_oops_in_oop(HeapWord* ptr) { | |
7423 assert(_bit_map->isMarked(ptr), "expected bit to be set"); | |
7424 // Should we assert that our work queue is empty or | |
7425 // below some drain limit? | |
7426 assert(_work_queue->size() == 0, | |
7427 "should drain stack to limit stack usage"); | |
7428 // convert ptr to an oop preparatory to scanning | |
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7429 oop obj = oop(ptr); |
0 | 7430 // Ignore mark word in verification below, since we |
7431 // may be running concurrent with mutators. | |
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7432 assert(obj->is_oop(true), "should be an oop"); |
0 | 7433 assert(_finger <= ptr, "_finger runneth ahead"); |
7434 // advance the finger to right end of this object | |
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7435 _finger = ptr + obj->size(); |
0 | 7436 assert(_finger > ptr, "we just incremented it above"); |
7437 // On large heaps, it may take us some time to get through | |
7438 // the marking phase (especially if running iCMS). During | |
7439 // this time it's possible that a lot of mutations have | |
7440 // accumulated in the card table and the mod union table -- | |
7441 // these mutation records are redundant until we have | |
7442 // actually traced into the corresponding card. | |
7443 // Here, we check whether advancing the finger would make | |
7444 // us cross into a new card, and if so clear corresponding | |
7445 // cards in the MUT (preclean them in the card-table in the | |
7446 // future). | |
7447 | |
7448 // The clean-on-enter optimization is disabled by default, | |
7449 // until we fix 6178663. | |
7450 if (CMSCleanOnEnter && (_finger > _threshold)) { | |
7451 // [_threshold, _finger) represents the interval | |
7452 // of cards to be cleared in MUT (or precleaned in card table). | |
7453 // The set of cards to be cleared is all those that overlap | |
7454 // with the interval [_threshold, _finger); note that | |
7455 // _threshold is always kept card-aligned but _finger isn't | |
7456 // always card-aligned. | |
7457 HeapWord* old_threshold = _threshold; | |
7458 assert(old_threshold == (HeapWord*)round_to( | |
7459 (intptr_t)old_threshold, CardTableModRefBS::card_size), | |
7460 "_threshold should always be card-aligned"); | |
7461 _threshold = (HeapWord*)round_to( | |
7462 (intptr_t)_finger, CardTableModRefBS::card_size); | |
7463 MemRegion mr(old_threshold, _threshold); | |
7464 assert(!mr.is_empty(), "Control point invariant"); | |
7465 assert(_span.contains(mr), "Should clear within span"); // _whole_span ?? | |
7466 _mut->clear_range(mr); | |
7467 } | |
7468 | |
7469 // Note: the local finger doesn't advance while we drain | |
7470 // the stack below, but the global finger sure can and will. | |
7471 HeapWord** gfa = _task->global_finger_addr(); | |
7472 Par_PushOrMarkClosure pushOrMarkClosure(_collector, | |
7473 _span, _bit_map, | |
7474 _work_queue, | |
7475 _overflow_stack, | |
7476 _finger, | |
7477 gfa, this); | |
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7478 bool res = _work_queue->push(obj); // overflow could occur here |
0 | 7479 assert(res, "Will hold once we use workqueues"); |
7480 while (true) { | |
7481 oop new_oop; | |
7482 if (!_work_queue->pop_local(new_oop)) { | |
7483 // We emptied our work_queue; check if there's stuff that can | |
7484 // be gotten from the overflow stack. | |
7485 if (CMSConcMarkingTask::get_work_from_overflow_stack( | |
7486 _overflow_stack, _work_queue)) { | |
7487 do_yield_check(); | |
7488 continue; | |
7489 } else { // done | |
7490 break; | |
7491 } | |
7492 } | |
7493 // Skip verifying header mark word below because we are | |
7494 // running concurrent with mutators. | |
7495 assert(new_oop->is_oop(true), "Oops! expected to pop an oop"); | |
7496 // now scan this oop's oops | |
7497 new_oop->oop_iterate(&pushOrMarkClosure); | |
7498 do_yield_check(); | |
7499 } | |
7500 assert(_work_queue->size() == 0, "tautology, emphasizing post-condition"); | |
7501 } | |
7502 | |
7503 // Yield in response to a request from VM Thread or | |
7504 // from mutators. | |
7505 void Par_MarkFromRootsClosure::do_yield_work() { | |
7506 assert(_task != NULL, "sanity"); | |
7507 _task->yield(); | |
7508 } | |
7509 | |
7510 // A variant of the above used for verifying CMS marking work. | |
7511 MarkFromRootsVerifyClosure::MarkFromRootsVerifyClosure(CMSCollector* collector, | |
7512 MemRegion span, | |
7513 CMSBitMap* verification_bm, CMSBitMap* cms_bm, | |
7514 CMSMarkStack* mark_stack): | |
7515 _collector(collector), | |
7516 _span(span), | |
7517 _verification_bm(verification_bm), | |
7518 _cms_bm(cms_bm), | |
7519 _mark_stack(mark_stack), | |
7520 _pam_verify_closure(collector, span, verification_bm, cms_bm, | |
7521 mark_stack) | |
7522 { | |
7523 assert(_mark_stack->isEmpty(), "stack should be empty"); | |
7524 _finger = _verification_bm->startWord(); | |
7525 assert(_collector->_restart_addr == NULL, "Sanity check"); | |
7526 assert(_span.contains(_finger), "Out of bounds _finger?"); | |
7527 } | |
7528 | |
7529 void MarkFromRootsVerifyClosure::reset(HeapWord* addr) { | |
7530 assert(_mark_stack->isEmpty(), "would cause duplicates on stack"); | |
7531 assert(_span.contains(addr), "Out of bounds _finger?"); | |
7532 _finger = addr; | |
7533 } | |
7534 | |
7535 // Should revisit to see if this should be restructured for | |
7536 // greater efficiency. | |
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7537 bool MarkFromRootsVerifyClosure::do_bit(size_t offset) { |
0 | 7538 // convert offset into a HeapWord* |
7539 HeapWord* addr = _verification_bm->startWord() + offset; | |
7540 assert(_verification_bm->endWord() && addr < _verification_bm->endWord(), | |
7541 "address out of range"); | |
7542 assert(_verification_bm->isMarked(addr), "tautology"); | |
7543 assert(_cms_bm->isMarked(addr), "tautology"); | |
7544 | |
7545 assert(_mark_stack->isEmpty(), | |
7546 "should drain stack to limit stack usage"); | |
7547 // convert addr to an oop preparatory to scanning | |
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7548 oop obj = oop(addr); |
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7549 assert(obj->is_oop(), "should be an oop"); |
0 | 7550 assert(_finger <= addr, "_finger runneth ahead"); |
7551 // advance the finger to right end of this object | |
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7552 _finger = addr + obj->size(); |
0 | 7553 assert(_finger > addr, "we just incremented it above"); |
7554 // Note: the finger doesn't advance while we drain | |
7555 // the stack below. | |
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7556 bool res = _mark_stack->push(obj); |
0 | 7557 assert(res, "Empty non-zero size stack should have space for single push"); |
7558 while (!_mark_stack->isEmpty()) { | |
7559 oop new_oop = _mark_stack->pop(); | |
7560 assert(new_oop->is_oop(), "Oops! expected to pop an oop"); | |
7561 // now scan this oop's oops | |
7562 new_oop->oop_iterate(&_pam_verify_closure); | |
7563 } | |
7564 assert(_mark_stack->isEmpty(), "tautology, emphasizing post-condition"); | |
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7565 return true; |
0 | 7566 } |
7567 | |
7568 PushAndMarkVerifyClosure::PushAndMarkVerifyClosure( | |
7569 CMSCollector* collector, MemRegion span, | |
7570 CMSBitMap* verification_bm, CMSBitMap* cms_bm, | |
7571 CMSMarkStack* mark_stack): | |
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7572 CMSOopClosure(collector->ref_processor()), |
0 | 7573 _collector(collector), |
7574 _span(span), | |
7575 _verification_bm(verification_bm), | |
7576 _cms_bm(cms_bm), | |
7577 _mark_stack(mark_stack) | |
7578 { } | |
7579 | |
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7580 void PushAndMarkVerifyClosure::do_oop(oop* p) { PushAndMarkVerifyClosure::do_oop_work(p); } |
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7581 void PushAndMarkVerifyClosure::do_oop(narrowOop* p) { PushAndMarkVerifyClosure::do_oop_work(p); } |
0 | 7582 |
7583 // Upon stack overflow, we discard (part of) the stack, | |
7584 // remembering the least address amongst those discarded | |
7585 // in CMSCollector's _restart_address. | |
7586 void PushAndMarkVerifyClosure::handle_stack_overflow(HeapWord* lost) { | |
7587 // Remember the least grey address discarded | |
7588 HeapWord* ra = (HeapWord*)_mark_stack->least_value(lost); | |
7589 _collector->lower_restart_addr(ra); | |
7590 _mark_stack->reset(); // discard stack contents | |
7591 _mark_stack->expand(); // expand the stack if possible | |
7592 } | |
7593 | |
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7594 void PushAndMarkVerifyClosure::do_oop(oop obj) { |
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7595 assert(obj->is_oop_or_null(), "expected an oop or NULL"); |
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7596 HeapWord* addr = (HeapWord*)obj; |
0 | 7597 if (_span.contains(addr) && !_verification_bm->isMarked(addr)) { |
7598 // Oop lies in _span and isn't yet grey or black | |
7599 _verification_bm->mark(addr); // now grey | |
7600 if (!_cms_bm->isMarked(addr)) { | |
7601 oop(addr)->print(); | |
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7602 gclog_or_tty->print_cr(" (" INTPTR_FORMAT " should have been marked)", |
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7603 addr); |
0 | 7604 fatal("... aborting"); |
7605 } | |
7606 | |
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7607 if (!_mark_stack->push(obj)) { // stack overflow |
0 | 7608 if (PrintCMSStatistics != 0) { |
7609 gclog_or_tty->print_cr("CMS marking stack overflow (benign) at " | |
7610 SIZE_FORMAT, _mark_stack->capacity()); | |
7611 } | |
7612 assert(_mark_stack->isFull(), "Else push should have succeeded"); | |
7613 handle_stack_overflow(addr); | |
7614 } | |
7615 // anything including and to the right of _finger | |
7616 // will be scanned as we iterate over the remainder of the | |
7617 // bit map | |
7618 } | |
7619 } | |
7620 | |
7621 PushOrMarkClosure::PushOrMarkClosure(CMSCollector* collector, | |
7622 MemRegion span, | |
7623 CMSBitMap* bitMap, CMSMarkStack* markStack, | |
7624 HeapWord* finger, MarkFromRootsClosure* parent) : | |
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7625 CMSOopClosure(collector->ref_processor()), |
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7626 _collector(collector), |
0 | 7627 _span(span), |
7628 _bitMap(bitMap), | |
7629 _markStack(markStack), | |
7630 _finger(finger), | |
935 | 7631 _parent(parent) |
0 | 7632 { } |
7633 | |
7634 Par_PushOrMarkClosure::Par_PushOrMarkClosure(CMSCollector* collector, | |
7635 MemRegion span, | |
7636 CMSBitMap* bit_map, | |
7637 OopTaskQueue* work_queue, | |
7638 CMSMarkStack* overflow_stack, | |
7639 HeapWord* finger, | |
7640 HeapWord** global_finger_addr, | |
7641 Par_MarkFromRootsClosure* parent) : | |
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7642 CMSOopClosure(collector->ref_processor()), |
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7643 _collector(collector), |
0 | 7644 _whole_span(collector->_span), |
7645 _span(span), | |
7646 _bit_map(bit_map), | |
7647 _work_queue(work_queue), | |
7648 _overflow_stack(overflow_stack), | |
7649 _finger(finger), | |
7650 _global_finger_addr(global_finger_addr), | |
935 | 7651 _parent(parent) |
0 | 7652 { } |
7653 | |
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7654 // Assumes thread-safe access by callers, who are |
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7655 // responsible for mutual exclusion. |
0 | 7656 void CMSCollector::lower_restart_addr(HeapWord* low) { |
7657 assert(_span.contains(low), "Out of bounds addr"); | |
7658 if (_restart_addr == NULL) { | |
7659 _restart_addr = low; | |
7660 } else { | |
7661 _restart_addr = MIN2(_restart_addr, low); | |
7662 } | |
7663 } | |
7664 | |
7665 // Upon stack overflow, we discard (part of) the stack, | |
7666 // remembering the least address amongst those discarded | |
7667 // in CMSCollector's _restart_address. | |
7668 void PushOrMarkClosure::handle_stack_overflow(HeapWord* lost) { | |
7669 // Remember the least grey address discarded | |
7670 HeapWord* ra = (HeapWord*)_markStack->least_value(lost); | |
7671 _collector->lower_restart_addr(ra); | |
7672 _markStack->reset(); // discard stack contents | |
7673 _markStack->expand(); // expand the stack if possible | |
7674 } | |
7675 | |
7676 // Upon stack overflow, we discard (part of) the stack, | |
7677 // remembering the least address amongst those discarded | |
7678 // in CMSCollector's _restart_address. | |
7679 void Par_PushOrMarkClosure::handle_stack_overflow(HeapWord* lost) { | |
7680 // We need to do this under a mutex to prevent other | |
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7681 // workers from interfering with the work done below. |
0 | 7682 MutexLockerEx ml(_overflow_stack->par_lock(), |
7683 Mutex::_no_safepoint_check_flag); | |
7684 // Remember the least grey address discarded | |
7685 HeapWord* ra = (HeapWord*)_overflow_stack->least_value(lost); | |
7686 _collector->lower_restart_addr(ra); | |
7687 _overflow_stack->reset(); // discard stack contents | |
7688 _overflow_stack->expand(); // expand the stack if possible | |
7689 } | |
7690 | |
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7691 void CMKlassClosure::do_klass(Klass* k) { |
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7692 assert(_oop_closure != NULL, "Not initialized?"); |
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7693 k->oops_do(_oop_closure); |
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7694 } |
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7695 |
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7696 void PushOrMarkClosure::do_oop(oop obj) { |
0 | 7697 // Ignore mark word because we are running concurrent with mutators. |
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7698 assert(obj->is_oop_or_null(true), "expected an oop or NULL"); |
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7699 HeapWord* addr = (HeapWord*)obj; |
0 | 7700 if (_span.contains(addr) && !_bitMap->isMarked(addr)) { |
7701 // Oop lies in _span and isn't yet grey or black | |
7702 _bitMap->mark(addr); // now grey | |
7703 if (addr < _finger) { | |
7704 // the bit map iteration has already either passed, or | |
7705 // sampled, this bit in the bit map; we'll need to | |
7706 // use the marking stack to scan this oop's oops. | |
7707 bool simulate_overflow = false; | |
7708 NOT_PRODUCT( | |
7709 if (CMSMarkStackOverflowALot && | |
7710 _collector->simulate_overflow()) { | |
7711 // simulate a stack overflow | |
7712 simulate_overflow = true; | |
7713 } | |
7714 ) | |
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7715 if (simulate_overflow || !_markStack->push(obj)) { // stack overflow |
0 | 7716 if (PrintCMSStatistics != 0) { |
7717 gclog_or_tty->print_cr("CMS marking stack overflow (benign) at " | |
7718 SIZE_FORMAT, _markStack->capacity()); | |
7719 } | |
7720 assert(simulate_overflow || _markStack->isFull(), "Else push should have succeeded"); | |
7721 handle_stack_overflow(addr); | |
7722 } | |
7723 } | |
7724 // anything including and to the right of _finger | |
7725 // will be scanned as we iterate over the remainder of the | |
7726 // bit map | |
7727 do_yield_check(); | |
7728 } | |
7729 } | |
7730 | |
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7731 void PushOrMarkClosure::do_oop(oop* p) { PushOrMarkClosure::do_oop_work(p); } |
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7732 void PushOrMarkClosure::do_oop(narrowOop* p) { PushOrMarkClosure::do_oop_work(p); } |
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7733 |
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7734 void Par_PushOrMarkClosure::do_oop(oop obj) { |
0 | 7735 // Ignore mark word because we are running concurrent with mutators. |
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7736 assert(obj->is_oop_or_null(true), "expected an oop or NULL"); |
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7737 HeapWord* addr = (HeapWord*)obj; |
0 | 7738 if (_whole_span.contains(addr) && !_bit_map->isMarked(addr)) { |
7739 // Oop lies in _span and isn't yet grey or black | |
7740 // We read the global_finger (volatile read) strictly after marking oop | |
7741 bool res = _bit_map->par_mark(addr); // now grey | |
7742 volatile HeapWord** gfa = (volatile HeapWord**)_global_finger_addr; | |
7743 // Should we push this marked oop on our stack? | |
7744 // -- if someone else marked it, nothing to do | |
7745 // -- if target oop is above global finger nothing to do | |
7746 // -- if target oop is in chunk and above local finger | |
7747 // then nothing to do | |
7748 // -- else push on work queue | |
7749 if ( !res // someone else marked it, they will deal with it | |
7750 || (addr >= *gfa) // will be scanned in a later task | |
7751 || (_span.contains(addr) && addr >= _finger)) { // later in this chunk | |
7752 return; | |
7753 } | |
7754 // the bit map iteration has already either passed, or | |
7755 // sampled, this bit in the bit map; we'll need to | |
7756 // use the marking stack to scan this oop's oops. | |
7757 bool simulate_overflow = false; | |
7758 NOT_PRODUCT( | |
7759 if (CMSMarkStackOverflowALot && | |
7760 _collector->simulate_overflow()) { | |
7761 // simulate a stack overflow | |
7762 simulate_overflow = true; | |
7763 } | |
7764 ) | |
7765 if (simulate_overflow || | |
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7766 !(_work_queue->push(obj) || _overflow_stack->par_push(obj))) { |
0 | 7767 // stack overflow |
7768 if (PrintCMSStatistics != 0) { | |
7769 gclog_or_tty->print_cr("CMS marking stack overflow (benign) at " | |
7770 SIZE_FORMAT, _overflow_stack->capacity()); | |
7771 } | |
7772 // We cannot assert that the overflow stack is full because | |
7773 // it may have been emptied since. | |
7774 assert(simulate_overflow || | |
7775 _work_queue->size() == _work_queue->max_elems(), | |
7776 "Else push should have succeeded"); | |
7777 handle_stack_overflow(addr); | |
7778 } | |
7779 do_yield_check(); | |
7780 } | |
7781 } | |
7782 | |
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7783 void Par_PushOrMarkClosure::do_oop(oop* p) { Par_PushOrMarkClosure::do_oop_work(p); } |
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7784 void Par_PushOrMarkClosure::do_oop(narrowOop* p) { Par_PushOrMarkClosure::do_oop_work(p); } |
0 | 7785 |
7786 PushAndMarkClosure::PushAndMarkClosure(CMSCollector* collector, | |
7787 MemRegion span, | |
7788 ReferenceProcessor* rp, | |
7789 CMSBitMap* bit_map, | |
7790 CMSBitMap* mod_union_table, | |
7791 CMSMarkStack* mark_stack, | |
7792 bool concurrent_precleaning): | |
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7793 CMSOopClosure(rp), |
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7794 _collector(collector), |
0 | 7795 _span(span), |
7796 _bit_map(bit_map), | |
7797 _mod_union_table(mod_union_table), | |
7798 _mark_stack(mark_stack), | |
935 | 7799 _concurrent_precleaning(concurrent_precleaning) |
0 | 7800 { |
7801 assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL"); | |
7802 } | |
7803 | |
7804 // Grey object rescan during pre-cleaning and second checkpoint phases -- | |
7805 // the non-parallel version (the parallel version appears further below.) | |
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7806 void PushAndMarkClosure::do_oop(oop obj) { |
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7807 // Ignore mark word verification. If during concurrent precleaning, |
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7808 // the object monitor may be locked. If during the checkpoint |
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7809 // phases, the object may already have been reached by a different |
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7810 // path and may be at the end of the global overflow list (so |
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7811 // the mark word may be NULL). |
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7812 assert(obj->is_oop_or_null(true /* ignore mark word */), |
0 | 7813 "expected an oop or NULL"); |
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7814 HeapWord* addr = (HeapWord*)obj; |
0 | 7815 // Check if oop points into the CMS generation |
7816 // and is not marked | |
7817 if (_span.contains(addr) && !_bit_map->isMarked(addr)) { | |
7818 // a white object ... | |
7819 _bit_map->mark(addr); // ... now grey | |
7820 // push on the marking stack (grey set) | |
7821 bool simulate_overflow = false; | |
7822 NOT_PRODUCT( | |
7823 if (CMSMarkStackOverflowALot && | |
7824 _collector->simulate_overflow()) { | |
7825 // simulate a stack overflow | |
7826 simulate_overflow = true; | |
7827 } | |
7828 ) | |
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7829 if (simulate_overflow || !_mark_stack->push(obj)) { |
0 | 7830 if (_concurrent_precleaning) { |
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7831 // During precleaning we can just dirty the appropriate card(s) |
0 | 7832 // in the mod union table, thus ensuring that the object remains |
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7833 // in the grey set and continue. In the case of object arrays |
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7834 // we need to dirty all of the cards that the object spans, |
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7835 // since the rescan of object arrays will be limited to the |
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7836 // dirty cards. |
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7837 // Note that no one can be intefering with us in this action |
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7838 // of dirtying the mod union table, so no locking or atomics |
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7839 // are required. |
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7840 if (obj->is_objArray()) { |
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7841 size_t sz = obj->size(); |
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7842 HeapWord* end_card_addr = (HeapWord*)round_to( |
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7843 (intptr_t)(addr+sz), CardTableModRefBS::card_size); |
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7844 MemRegion redirty_range = MemRegion(addr, end_card_addr); |
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7845 assert(!redirty_range.is_empty(), "Arithmetical tautology"); |
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7846 _mod_union_table->mark_range(redirty_range); |
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7847 } else { |
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7848 _mod_union_table->mark(addr); |
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7849 } |
0 | 7850 _collector->_ser_pmc_preclean_ovflw++; |
7851 } else { | |
7852 // During the remark phase, we need to remember this oop | |
7853 // in the overflow list. | |
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7854 _collector->push_on_overflow_list(obj); |
0 | 7855 _collector->_ser_pmc_remark_ovflw++; |
7856 } | |
7857 } | |
7858 } | |
7859 } | |
7860 | |
7861 Par_PushAndMarkClosure::Par_PushAndMarkClosure(CMSCollector* collector, | |
7862 MemRegion span, | |
7863 ReferenceProcessor* rp, | |
7864 CMSBitMap* bit_map, | |
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7865 OopTaskQueue* work_queue): |
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7866 CMSOopClosure(rp), |
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7867 _collector(collector), |
0 | 7868 _span(span), |
7869 _bit_map(bit_map), | |
935 | 7870 _work_queue(work_queue) |
0 | 7871 { |
7872 assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL"); | |
7873 } | |
7874 | |
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7875 void PushAndMarkClosure::do_oop(oop* p) { PushAndMarkClosure::do_oop_work(p); } |
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7876 void PushAndMarkClosure::do_oop(narrowOop* p) { PushAndMarkClosure::do_oop_work(p); } |
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7877 |
0 | 7878 // Grey object rescan during second checkpoint phase -- |
7879 // the parallel version. | |
113
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7880 void Par_PushAndMarkClosure::do_oop(oop obj) { |
0 | 7881 // In the assert below, we ignore the mark word because |
7882 // this oop may point to an already visited object that is | |
7883 // on the overflow stack (in which case the mark word has | |
7884 // been hijacked for chaining into the overflow stack -- | |
7885 // if this is the last object in the overflow stack then | |
7886 // its mark word will be NULL). Because this object may | |
7887 // have been subsequently popped off the global overflow | |
7888 // stack, and the mark word possibly restored to the prototypical | |
7889 // value, by the time we get to examined this failing assert in | |
7890 // the debugger, is_oop_or_null(false) may subsequently start | |
7891 // to hold. | |
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7892 assert(obj->is_oop_or_null(true), |
0 | 7893 "expected an oop or NULL"); |
113
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7894 HeapWord* addr = (HeapWord*)obj; |
0 | 7895 // Check if oop points into the CMS generation |
7896 // and is not marked | |
7897 if (_span.contains(addr) && !_bit_map->isMarked(addr)) { | |
7898 // a white object ... | |
7899 // If we manage to "claim" the object, by being the | |
7900 // first thread to mark it, then we push it on our | |
7901 // marking stack | |
7902 if (_bit_map->par_mark(addr)) { // ... now grey | |
7903 // push on work queue (grey set) | |
7904 bool simulate_overflow = false; | |
7905 NOT_PRODUCT( | |
7906 if (CMSMarkStackOverflowALot && | |
7907 _collector->par_simulate_overflow()) { | |
7908 // simulate a stack overflow | |
7909 simulate_overflow = true; | |
7910 } | |
7911 ) | |
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7912 if (simulate_overflow || !_work_queue->push(obj)) { |
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7913 _collector->par_push_on_overflow_list(obj); |
0 | 7914 _collector->_par_pmc_remark_ovflw++; // imprecise OK: no need to CAS |
7915 } | |
7916 } // Else, some other thread got there first | |
7917 } | |
7918 } | |
7919 | |
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7920 void Par_PushAndMarkClosure::do_oop(oop* p) { Par_PushAndMarkClosure::do_oop_work(p); } |
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7921 void Par_PushAndMarkClosure::do_oop(narrowOop* p) { Par_PushAndMarkClosure::do_oop_work(p); } |
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7922 |
0 | 7923 void CMSPrecleanRefsYieldClosure::do_yield_work() { |
7924 Mutex* bml = _collector->bitMapLock(); | |
7925 assert_lock_strong(bml); | |
7926 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
7927 "CMS thread should hold CMS token"); | |
7928 | |
7929 bml->unlock(); | |
7930 ConcurrentMarkSweepThread::desynchronize(true); | |
7931 | |
7932 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
7933 | |
7934 _collector->stopTimer(); | |
7935 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
7936 if (PrintCMSStatistics != 0) { | |
7937 _collector->incrementYields(); | |
7938 } | |
7939 _collector->icms_wait(); | |
7940 | |
7941 // See the comment in coordinator_yield() | |
7942 for (unsigned i = 0; i < CMSYieldSleepCount && | |
7943 ConcurrentMarkSweepThread::should_yield() && | |
7944 !CMSCollector::foregroundGCIsActive(); ++i) { | |
7945 os::sleep(Thread::current(), 1, false); | |
7946 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
7947 } | |
7948 | |
7949 ConcurrentMarkSweepThread::synchronize(true); | |
7950 bml->lock(); | |
7951 | |
7952 _collector->startTimer(); | |
7953 } | |
7954 | |
7955 bool CMSPrecleanRefsYieldClosure::should_return() { | |
7956 if (ConcurrentMarkSweepThread::should_yield()) { | |
7957 do_yield_work(); | |
7958 } | |
7959 return _collector->foregroundGCIsActive(); | |
7960 } | |
7961 | |
7962 void MarkFromDirtyCardsClosure::do_MemRegion(MemRegion mr) { | |
7963 assert(((size_t)mr.start())%CardTableModRefBS::card_size_in_words == 0, | |
7964 "mr should be aligned to start at a card boundary"); | |
7965 // We'd like to assert: | |
7966 // assert(mr.word_size()%CardTableModRefBS::card_size_in_words == 0, | |
7967 // "mr should be a range of cards"); | |
7968 // However, that would be too strong in one case -- the last | |
7969 // partition ends at _unallocated_block which, in general, can be | |
7970 // an arbitrary boundary, not necessarily card aligned. | |
7971 if (PrintCMSStatistics != 0) { | |
7972 _num_dirty_cards += | |
7973 mr.word_size()/CardTableModRefBS::card_size_in_words; | |
7974 } | |
7975 _space->object_iterate_mem(mr, &_scan_cl); | |
7976 } | |
7977 | |
7978 SweepClosure::SweepClosure(CMSCollector* collector, | |
7979 ConcurrentMarkSweepGeneration* g, | |
7980 CMSBitMap* bitMap, bool should_yield) : | |
7981 _collector(collector), | |
7982 _g(g), | |
7983 _sp(g->cmsSpace()), | |
7984 _limit(_sp->sweep_limit()), | |
7985 _freelistLock(_sp->freelistLock()), | |
7986 _bitMap(bitMap), | |
7987 _yield(should_yield), | |
7988 _inFreeRange(false), // No free range at beginning of sweep | |
7989 _freeRangeInFreeLists(false), // No free range at beginning of sweep | |
7990 _lastFreeRangeCoalesced(false), | |
7991 _freeFinger(g->used_region().start()) | |
7992 { | |
7993 NOT_PRODUCT( | |
7994 _numObjectsFreed = 0; | |
7995 _numWordsFreed = 0; | |
7996 _numObjectsLive = 0; | |
7997 _numWordsLive = 0; | |
7998 _numObjectsAlreadyFree = 0; | |
7999 _numWordsAlreadyFree = 0; | |
8000 _last_fc = NULL; | |
8001 | |
8002 _sp->initializeIndexedFreeListArrayReturnedBytes(); | |
6028
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8003 _sp->dictionary()->initialize_dict_returned_bytes(); |
0 | 8004 ) |
8005 assert(_limit >= _sp->bottom() && _limit <= _sp->end(), | |
8006 "sweep _limit out of bounds"); | |
8007 if (CMSTraceSweeper) { | |
3746
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8008 gclog_or_tty->print_cr("\n====================\nStarting new sweep with limit " PTR_FORMAT, |
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8009 _limit); |
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8010 } |
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8011 } |
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8012 |
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8013 void SweepClosure::print_on(outputStream* st) const { |
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8014 tty->print_cr("_sp = [" PTR_FORMAT "," PTR_FORMAT ")", |
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8015 _sp->bottom(), _sp->end()); |
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8016 tty->print_cr("_limit = " PTR_FORMAT, _limit); |
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8017 tty->print_cr("_freeFinger = " PTR_FORMAT, _freeFinger); |
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8018 NOT_PRODUCT(tty->print_cr("_last_fc = " PTR_FORMAT, _last_fc);) |
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8019 tty->print_cr("_inFreeRange = %d, _freeRangeInFreeLists = %d, _lastFreeRangeCoalesced = %d", |
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8020 _inFreeRange, _freeRangeInFreeLists, _lastFreeRangeCoalesced); |
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8021 } |
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8022 |
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8023 #ifndef PRODUCT |
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8024 // Assertion checking only: no useful work in product mode -- |
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8025 // however, if any of the flags below become product flags, |
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8026 // you may need to review this code to see if it needs to be |
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8027 // enabled in product mode. |
0 | 8028 SweepClosure::~SweepClosure() { |
8029 assert_lock_strong(_freelistLock); | |
2132
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8030 assert(_limit >= _sp->bottom() && _limit <= _sp->end(), |
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8031 "sweep _limit out of bounds"); |
0 | 8032 if (inFreeRange()) { |
3746
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8033 warning("inFreeRange() should have been reset; dumping state of SweepClosure"); |
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8034 print(); |
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8035 ShouldNotReachHere(); |
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8036 } |
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8037 if (Verbose && PrintGC) { |
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8038 gclog_or_tty->print("Collected "SIZE_FORMAT" objects, " SIZE_FORMAT " bytes", |
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8039 _numObjectsFreed, _numWordsFreed*sizeof(HeapWord)); |
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8040 gclog_or_tty->print_cr("\nLive "SIZE_FORMAT" objects, " |
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8041 SIZE_FORMAT" bytes " |
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|
8042 "Already free "SIZE_FORMAT" objects, "SIZE_FORMAT" bytes", |
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8043 _numObjectsLive, _numWordsLive*sizeof(HeapWord), |
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8044 _numObjectsAlreadyFree, _numWordsAlreadyFree*sizeof(HeapWord)); |
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8045 size_t totalBytes = (_numWordsFreed + _numWordsLive + _numWordsAlreadyFree) |
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8046 * sizeof(HeapWord); |
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8047 gclog_or_tty->print_cr("Total sweep: "SIZE_FORMAT" bytes", totalBytes); |
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8048 |
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8049 if (PrintCMSStatistics && CMSVerifyReturnedBytes) { |
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8050 size_t indexListReturnedBytes = _sp->sumIndexedFreeListArrayReturnedBytes(); |
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8051 size_t dict_returned_bytes = _sp->dictionary()->sum_dict_returned_bytes(); |
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8052 size_t returned_bytes = indexListReturnedBytes + dict_returned_bytes; |
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8053 gclog_or_tty->print("Returned "SIZE_FORMAT" bytes", returned_bytes); |
3746
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8054 gclog_or_tty->print(" Indexed List Returned "SIZE_FORMAT" bytes", |
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8055 indexListReturnedBytes); |
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|
8056 gclog_or_tty->print_cr(" Dictionary Returned "SIZE_FORMAT" bytes", |
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8057 dict_returned_bytes); |
3746
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8058 } |
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8059 } |
0 | 8060 if (CMSTraceSweeper) { |
3746
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8061 gclog_or_tty->print_cr("end of sweep with _limit = " PTR_FORMAT "\n================", |
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8062 _limit); |
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8063 } |
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8064 } |
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8065 #endif // PRODUCT |
0 | 8066 |
8067 void SweepClosure::initialize_free_range(HeapWord* freeFinger, | |
8068 bool freeRangeInFreeLists) { | |
8069 if (CMSTraceSweeper) { | |
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8070 gclog_or_tty->print("---- Start free range at 0x%x with free block (%d)\n", |
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8071 freeFinger, freeRangeInFreeLists); |
0 | 8072 } |
8073 assert(!inFreeRange(), "Trampling existing free range"); | |
8074 set_inFreeRange(true); | |
8075 set_lastFreeRangeCoalesced(false); | |
8076 | |
8077 set_freeFinger(freeFinger); | |
8078 set_freeRangeInFreeLists(freeRangeInFreeLists); | |
8079 if (CMSTestInFreeList) { | |
8080 if (freeRangeInFreeLists) { | |
8081 FreeChunk* fc = (FreeChunk*) freeFinger; | |
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8082 assert(fc->is_free(), "A chunk on the free list should be free."); |
0 | 8083 assert(fc->size() > 0, "Free range should have a size"); |
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8084 assert(_sp->verify_chunk_in_free_list(fc), "Chunk is not in free lists"); |
0 | 8085 } |
8086 } | |
8087 } | |
8088 | |
8089 // Note that the sweeper runs concurrently with mutators. Thus, | |
8090 // it is possible for direct allocation in this generation to happen | |
8091 // in the middle of the sweep. Note that the sweeper also coalesces | |
8092 // contiguous free blocks. Thus, unless the sweeper and the allocator | |
8093 // synchronize appropriately freshly allocated blocks may get swept up. | |
8094 // This is accomplished by the sweeper locking the free lists while | |
8095 // it is sweeping. Thus blocks that are determined to be free are | |
8096 // indeed free. There is however one additional complication: | |
8097 // blocks that have been allocated since the final checkpoint and | |
8098 // mark, will not have been marked and so would be treated as | |
8099 // unreachable and swept up. To prevent this, the allocator marks | |
8100 // the bit map when allocating during the sweep phase. This leads, | |
8101 // however, to a further complication -- objects may have been allocated | |
8102 // but not yet initialized -- in the sense that the header isn't yet | |
8103 // installed. The sweeper can not then determine the size of the block | |
8104 // in order to skip over it. To deal with this case, we use a technique | |
8105 // (due to Printezis) to encode such uninitialized block sizes in the | |
8106 // bit map. Since the bit map uses a bit per every HeapWord, but the | |
8107 // CMS generation has a minimum object size of 3 HeapWords, it follows | |
8108 // that "normal marks" won't be adjacent in the bit map (there will | |
8109 // always be at least two 0 bits between successive 1 bits). We make use | |
8110 // of these "unused" bits to represent uninitialized blocks -- the bit | |
8111 // corresponding to the start of the uninitialized object and the next | |
8112 // bit are both set. Finally, a 1 bit marks the end of the object that | |
8113 // started with the two consecutive 1 bits to indicate its potentially | |
8114 // uninitialized state. | |
8115 | |
8116 size_t SweepClosure::do_blk_careful(HeapWord* addr) { | |
8117 FreeChunk* fc = (FreeChunk*)addr; | |
8118 size_t res; | |
8119 | |
1720
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8120 // Check if we are done sweeping. Below we check "addr >= _limit" rather |
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changeset
|
8121 // than "addr == _limit" because although _limit was a block boundary when |
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
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1716
diff
changeset
|
8122 // we started the sweep, it may no longer be one because heap expansion |
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
parents:
1716
diff
changeset
|
8123 // may have caused us to coalesce the block ending at the address _limit |
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
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1716
diff
changeset
|
8124 // with a newly expanded chunk (this happens when _limit was set to the |
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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|
8125 // previous _end of the space), so we may have stepped past _limit: |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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|
8126 // see the following Zeno-like trail of CRs 6977970, 7008136, 7042740. |
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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|
8127 if (addr >= _limit) { // we have swept up to or past the limit: finish up |
0 | 8128 assert(_limit >= _sp->bottom() && _limit <= _sp->end(), |
8129 "sweep _limit out of bounds"); | |
1720
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
parents:
1716
diff
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|
8130 assert(addr < _sp->end(), "addr out of bounds"); |
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
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changeset
|
8131 // Flush any free range we might be holding as a single |
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
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|
8132 // coalesced chunk to the appropriate free list. |
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8133 if (inFreeRange()) { |
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8134 assert(freeFinger() >= _sp->bottom() && freeFinger() < _limit, |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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|
8135 err_msg("freeFinger() " PTR_FORMAT" is out-of-bounds", freeFinger())); |
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8136 flush_cur_free_chunk(freeFinger(), |
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8137 pointer_delta(addr, freeFinger())); |
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8138 if (CMSTraceSweeper) { |
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8139 gclog_or_tty->print("Sweep: last chunk: "); |
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8140 gclog_or_tty->print("put_free_blk 0x%x ("SIZE_FORMAT") " |
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8141 "[coalesced:"SIZE_FORMAT"]\n", |
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8142 freeFinger(), pointer_delta(addr, freeFinger()), |
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8143 lastFreeRangeCoalesced()); |
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8144 } |
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8145 } |
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
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|
8146 |
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8147 // help the iterator loop finish |
1720
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
parents:
1716
diff
changeset
|
8148 return pointer_delta(_sp->end(), addr); |
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
parents:
1716
diff
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|
8149 } |
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8150 |
1720
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
parents:
1716
diff
changeset
|
8151 assert(addr < _limit, "sweep invariant"); |
0 | 8152 // check if we should yield |
8153 do_yield_check(addr); | |
6028
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
parents:
6026
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|
8154 if (fc->is_free()) { |
0 | 8155 // Chunk that is already free |
8156 res = fc->size(); | |
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8157 do_already_free_chunk(fc); |
0 | 8158 debug_only(_sp->verifyFreeLists()); |
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8159 // If we flush the chunk at hand in lookahead_and_flush() |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8160 // and it's coalesced with a preceding chunk, then the |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8161 // process of "mangling" the payload of the coalesced block |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8162 // will cause erasure of the size information from the |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8163 // (erstwhile) header of all the coalesced blocks but the |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8164 // first, so the first disjunct in the assert will not hold |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8165 // in that specific case (in which case the second disjunct |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8166 // will hold). |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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|
8167 assert(res == fc->size() || ((HeapWord*)fc) + res >= _limit, |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
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changeset
|
8168 "Otherwise the size info doesn't change at this step"); |
0 | 8169 NOT_PRODUCT( |
8170 _numObjectsAlreadyFree++; | |
8171 _numWordsAlreadyFree += res; | |
8172 ) | |
8173 NOT_PRODUCT(_last_fc = fc;) | |
8174 } else if (!_bitMap->isMarked(addr)) { | |
8175 // Chunk is fresh garbage | |
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8176 res = do_garbage_chunk(fc); |
0 | 8177 debug_only(_sp->verifyFreeLists()); |
8178 NOT_PRODUCT( | |
8179 _numObjectsFreed++; | |
8180 _numWordsFreed += res; | |
8181 ) | |
8182 } else { | |
8183 // Chunk that is alive. | |
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8184 res = do_live_chunk(fc); |
0 | 8185 debug_only(_sp->verifyFreeLists()); |
8186 NOT_PRODUCT( | |
8187 _numObjectsLive++; | |
8188 _numWordsLive += res; | |
8189 ) | |
8190 } | |
8191 return res; | |
8192 } | |
8193 | |
8194 // For the smart allocation, record following | |
8195 // split deaths - a free chunk is removed from its free list because | |
8196 // it is being split into two or more chunks. | |
8197 // split birth - a free chunk is being added to its free list because | |
8198 // a larger free chunk has been split and resulted in this free chunk. | |
8199 // coal death - a free chunk is being removed from its free list because | |
8200 // it is being coalesced into a large free chunk. | |
8201 // coal birth - a free chunk is being added to its free list because | |
8202 // it was created when two or more free chunks where coalesced into | |
8203 // this free chunk. | |
8204 // | |
8205 // These statistics are used to determine the desired number of free | |
8206 // chunks of a given size. The desired number is chosen to be relative | |
8207 // to the end of a CMS sweep. The desired number at the end of a sweep | |
8208 // is the | |
8209 // count-at-end-of-previous-sweep (an amount that was enough) | |
8210 // - count-at-beginning-of-current-sweep (the excess) | |
8211 // + split-births (gains in this size during interval) | |
8212 // - split-deaths (demands on this size during interval) | |
8213 // where the interval is from the end of one sweep to the end of the | |
8214 // next. | |
8215 // | |
8216 // When sweeping the sweeper maintains an accumulated chunk which is | |
8217 // the chunk that is made up of chunks that have been coalesced. That | |
8218 // will be termed the left-hand chunk. A new chunk of garbage that | |
8219 // is being considered for coalescing will be referred to as the | |
8220 // right-hand chunk. | |
8221 // | |
8222 // When making a decision on whether to coalesce a right-hand chunk with | |
8223 // the current left-hand chunk, the current count vs. the desired count | |
8224 // of the left-hand chunk is considered. Also if the right-hand chunk | |
8225 // is near the large chunk at the end of the heap (see | |
8226 // ConcurrentMarkSweepGeneration::isNearLargestChunk()), then the | |
8227 // left-hand chunk is coalesced. | |
8228 // | |
8229 // When making a decision about whether to split a chunk, the desired count | |
8230 // vs. the current count of the candidate to be split is also considered. | |
8231 // If the candidate is underpopulated (currently fewer chunks than desired) | |
8232 // a chunk of an overpopulated (currently more chunks than desired) size may | |
8233 // be chosen. The "hint" associated with a free list, if non-null, points | |
8234 // to a free list which may be overpopulated. | |
8235 // | |
8236 | |
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8237 void SweepClosure::do_already_free_chunk(FreeChunk* fc) { |
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8238 const size_t size = fc->size(); |
0 | 8239 // Chunks that cannot be coalesced are not in the |
8240 // free lists. | |
8241 if (CMSTestInFreeList && !fc->cantCoalesce()) { | |
6028
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
parents:
6026
diff
changeset
|
8242 assert(_sp->verify_chunk_in_free_list(fc), |
0 | 8243 "free chunk should be in free lists"); |
8244 } | |
8245 // a chunk that is already free, should not have been | |
8246 // marked in the bit map | |
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8247 HeapWord* const addr = (HeapWord*) fc; |
0 | 8248 assert(!_bitMap->isMarked(addr), "free chunk should be unmarked"); |
8249 // Verify that the bit map has no bits marked between | |
8250 // addr and purported end of this block. | |
8251 _bitMap->verifyNoOneBitsInRange(addr + 1, addr + size); | |
8252 | |
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8253 // Some chunks cannot be coalesced under any circumstances. |
0 | 8254 // See the definition of cantCoalesce(). |
8255 if (!fc->cantCoalesce()) { | |
8256 // This chunk can potentially be coalesced. | |
8257 if (_sp->adaptive_freelists()) { | |
8258 // All the work is done in | |
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8259 do_post_free_or_garbage_chunk(fc, size); |
0 | 8260 } else { // Not adaptive free lists |
8261 // this is a free chunk that can potentially be coalesced by the sweeper; | |
8262 if (!inFreeRange()) { | |
8263 // if the next chunk is a free block that can't be coalesced | |
8264 // it doesn't make sense to remove this chunk from the free lists | |
8265 FreeChunk* nextChunk = (FreeChunk*)(addr + size); | |
2136
c91cc404ca46
7011940: iCMS: SIGSEGV in SweepClosure::do_already_free_chunk(FreeChunk*)+0x360
ysr
parents:
2132
diff
changeset
|
8266 assert((HeapWord*)nextChunk <= _sp->end(), "Chunk size out of bounds?"); |
c91cc404ca46
7011940: iCMS: SIGSEGV in SweepClosure::do_already_free_chunk(FreeChunk*)+0x360
ysr
parents:
2132
diff
changeset
|
8267 if ((HeapWord*)nextChunk < _sp->end() && // There is another free chunk to the right ... |
6028
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
parents:
6026
diff
changeset
|
8268 nextChunk->is_free() && // ... which is free... |
2136
c91cc404ca46
7011940: iCMS: SIGSEGV in SweepClosure::do_already_free_chunk(FreeChunk*)+0x360
ysr
parents:
2132
diff
changeset
|
8269 nextChunk->cantCoalesce()) { // ... but can't be coalesced |
0 | 8270 // nothing to do |
8271 } else { | |
8272 // Potentially the start of a new free range: | |
8273 // Don't eagerly remove it from the free lists. | |
8274 // No need to remove it if it will just be put | |
8275 // back again. (Also from a pragmatic point of view | |
8276 // if it is a free block in a region that is beyond | |
8277 // any allocated blocks, an assertion will fail) | |
8278 // Remember the start of a free run. | |
8279 initialize_free_range(addr, true); | |
8280 // end - can coalesce with next chunk | |
8281 } | |
8282 } else { | |
8283 // the midst of a free range, we are coalescing | |
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8284 print_free_block_coalesced(fc); |
0 | 8285 if (CMSTraceSweeper) { |
8286 gclog_or_tty->print(" -- pick up free block 0x%x (%d)\n", fc, size); | |
8287 } | |
8288 // remove it from the free lists | |
8289 _sp->removeFreeChunkFromFreeLists(fc); | |
8290 set_lastFreeRangeCoalesced(true); | |
8291 // If the chunk is being coalesced and the current free range is | |
8292 // in the free lists, remove the current free range so that it | |
8293 // will be returned to the free lists in its entirety - all | |
8294 // the coalesced pieces included. | |
8295 if (freeRangeInFreeLists()) { | |
8296 FreeChunk* ffc = (FreeChunk*) freeFinger(); | |
8297 assert(ffc->size() == pointer_delta(addr, freeFinger()), | |
8298 "Size of free range is inconsistent with chunk size."); | |
8299 if (CMSTestInFreeList) { | |
6028
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
parents:
6026
diff
changeset
|
8300 assert(_sp->verify_chunk_in_free_list(ffc), |
0 | 8301 "free range is not in free lists"); |
8302 } | |
8303 _sp->removeFreeChunkFromFreeLists(ffc); | |
8304 set_freeRangeInFreeLists(false); | |
8305 } | |
8306 } | |
8307 } | |
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8308 // Note that if the chunk is not coalescable (the else arm |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8309 // below), we unconditionally flush, without needing to do |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8310 // a "lookahead," as we do below. |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8311 if (inFreeRange()) lookahead_and_flush(fc, size); |
0 | 8312 } else { |
8313 // Code path common to both original and adaptive free lists. | |
8314 | |
8315 // cant coalesce with previous block; this should be treated | |
8316 // as the end of a free run if any | |
8317 if (inFreeRange()) { | |
8318 // we kicked some butt; time to pick up the garbage | |
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8319 assert(freeFinger() < addr, "freeFinger points too high"); |
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8320 flush_cur_free_chunk(freeFinger(), pointer_delta(addr, freeFinger())); |
0 | 8321 } |
8322 // else, nothing to do, just continue | |
8323 } | |
8324 } | |
8325 | |
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8326 size_t SweepClosure::do_garbage_chunk(FreeChunk* fc) { |
0 | 8327 // This is a chunk of garbage. It is not in any free list. |
8328 // Add it to a free list or let it possibly be coalesced into | |
8329 // a larger chunk. | |
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8330 HeapWord* const addr = (HeapWord*) fc; |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
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|
8331 const size_t size = CompactibleFreeListSpace::adjustObjectSize(oop(addr)->size()); |
0 | 8332 |
8333 if (_sp->adaptive_freelists()) { | |
8334 // Verify that the bit map has no bits marked between | |
8335 // addr and purported end of just dead object. | |
8336 _bitMap->verifyNoOneBitsInRange(addr + 1, addr + size); | |
8337 | |
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8338 do_post_free_or_garbage_chunk(fc, size); |
0 | 8339 } else { |
8340 if (!inFreeRange()) { | |
8341 // start of a new free range | |
8342 assert(size > 0, "A free range should have a size"); | |
8343 initialize_free_range(addr, false); | |
8344 } else { | |
8345 // this will be swept up when we hit the end of the | |
8346 // free range | |
8347 if (CMSTraceSweeper) { | |
8348 gclog_or_tty->print(" -- pick up garbage 0x%x (%d) \n", fc, size); | |
8349 } | |
8350 // If the chunk is being coalesced and the current free range is | |
8351 // in the free lists, remove the current free range so that it | |
8352 // will be returned to the free lists in its entirety - all | |
8353 // the coalesced pieces included. | |
8354 if (freeRangeInFreeLists()) { | |
8355 FreeChunk* ffc = (FreeChunk*)freeFinger(); | |
8356 assert(ffc->size() == pointer_delta(addr, freeFinger()), | |
8357 "Size of free range is inconsistent with chunk size."); | |
8358 if (CMSTestInFreeList) { | |
6028
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jmasa
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6026
diff
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|
8359 assert(_sp->verify_chunk_in_free_list(ffc), |
0 | 8360 "free range is not in free lists"); |
8361 } | |
8362 _sp->removeFreeChunkFromFreeLists(ffc); | |
8363 set_freeRangeInFreeLists(false); | |
8364 } | |
8365 set_lastFreeRangeCoalesced(true); | |
8366 } | |
8367 // this will be swept up when we hit the end of the free range | |
8368 | |
8369 // Verify that the bit map has no bits marked between | |
8370 // addr and purported end of just dead object. | |
8371 _bitMap->verifyNoOneBitsInRange(addr + 1, addr + size); | |
8372 } | |
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8373 assert(_limit >= addr + size, |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8374 "A freshly garbage chunk can't possibly straddle over _limit"); |
537a4053b0f9
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changeset
|
8375 if (inFreeRange()) lookahead_and_flush(fc, size); |
0 | 8376 return size; |
8377 } | |
8378 | |
2132
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diff
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|
8379 size_t SweepClosure::do_live_chunk(FreeChunk* fc) { |
0 | 8380 HeapWord* addr = (HeapWord*) fc; |
8381 // The sweeper has just found a live object. Return any accumulated | |
8382 // left hand chunk to the free lists. | |
8383 if (inFreeRange()) { | |
2132
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1994
diff
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|
8384 assert(freeFinger() < addr, "freeFinger points too high"); |
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
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|
8385 flush_cur_free_chunk(freeFinger(), pointer_delta(addr, freeFinger())); |
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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|
8386 } |
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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diff
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|
8387 |
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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|
8388 // This object is live: we'd normally expect this to be |
0 | 8389 // an oop, and like to assert the following: |
8390 // assert(oop(addr)->is_oop(), "live block should be an oop"); | |
8391 // However, as we commented above, this may be an object whose | |
8392 // header hasn't yet been initialized. | |
8393 size_t size; | |
8394 assert(_bitMap->isMarked(addr), "Tautology for this control point"); | |
8395 if (_bitMap->isMarked(addr + 1)) { | |
8396 // Determine the size from the bit map, rather than trying to | |
8397 // compute it from the object header. | |
8398 HeapWord* nextOneAddr = _bitMap->getNextMarkedWordAddress(addr + 2); | |
8399 size = pointer_delta(nextOneAddr + 1, addr); | |
8400 assert(size == CompactibleFreeListSpace::adjustObjectSize(size), | |
8401 "alignment problem"); | |
8402 | |
9152 | 8403 #ifdef ASSERT |
6725
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
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|
8404 if (oop(addr)->klass_or_null() != NULL) { |
0 | 8405 // Ignore mark word because we are running concurrent with mutators |
8406 assert(oop(addr)->is_oop(true), "live block should be an oop"); | |
8407 assert(size == | |
8408 CompactibleFreeListSpace::adjustObjectSize(oop(addr)->size()), | |
8409 "P-mark and computed size do not agree"); | |
8410 } | |
2132
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|
8411 #endif |
0 | 8412 |
8413 } else { | |
8414 // This should be an initialized object that's alive. | |
6725
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|
8415 assert(oop(addr)->klass_or_null() != NULL, |
0 | 8416 "Should be an initialized object"); |
8417 // Ignore mark word because we are running concurrent with mutators | |
8418 assert(oop(addr)->is_oop(true), "live block should be an oop"); | |
8419 // Verify that the bit map has no bits marked between | |
8420 // addr and purported end of this block. | |
8421 size = CompactibleFreeListSpace::adjustObjectSize(oop(addr)->size()); | |
8422 assert(size >= 3, "Necessary for Printezis marks to work"); | |
8423 assert(!_bitMap->isMarked(addr+1), "Tautology for this control point"); | |
8424 DEBUG_ONLY(_bitMap->verifyNoOneBitsInRange(addr+2, addr+size);) | |
8425 } | |
8426 return size; | |
8427 } | |
8428 | |
2132
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1994
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changeset
|
8429 void SweepClosure::do_post_free_or_garbage_chunk(FreeChunk* fc, |
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
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|
8430 size_t chunkSize) { |
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
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|
8431 // do_post_free_or_garbage_chunk() should only be called in the case |
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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|
8432 // of the adaptive free list allocator. |
6028
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jmasa
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6026
diff
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|
8433 const bool fcInFreeLists = fc->is_free(); |
0 | 8434 assert(_sp->adaptive_freelists(), "Should only be used in this case."); |
8435 assert((HeapWord*)fc <= _limit, "sweep invariant"); | |
8436 if (CMSTestInFreeList && fcInFreeLists) { | |
6028
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jmasa
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6026
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|
8437 assert(_sp->verify_chunk_in_free_list(fc), "free chunk is not in free lists"); |
2132
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|
8438 } |
0 | 8439 |
8440 if (CMSTraceSweeper) { | |
8441 gclog_or_tty->print_cr(" -- pick up another chunk at 0x%x (%d)", fc, chunkSize); | |
8442 } | |
8443 | |
3746
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|
8444 HeapWord* const fc_addr = (HeapWord*) fc; |
0 | 8445 |
8446 bool coalesce; | |
3746
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7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8447 const size_t left = pointer_delta(fc_addr, freeFinger()); |
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7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8448 const size_t right = chunkSize; |
0 | 8449 switch (FLSCoalescePolicy) { |
8450 // numeric value forms a coalition aggressiveness metric | |
8451 case 0: { // never coalesce | |
8452 coalesce = false; | |
8453 break; | |
8454 } | |
8455 case 1: { // coalesce if left & right chunks on overpopulated lists | |
8456 coalesce = _sp->coalOverPopulated(left) && | |
8457 _sp->coalOverPopulated(right); | |
8458 break; | |
8459 } | |
8460 case 2: { // coalesce if left chunk on overpopulated list (default) | |
8461 coalesce = _sp->coalOverPopulated(left); | |
8462 break; | |
8463 } | |
8464 case 3: { // coalesce if left OR right chunk on overpopulated list | |
8465 coalesce = _sp->coalOverPopulated(left) || | |
8466 _sp->coalOverPopulated(right); | |
8467 break; | |
8468 } | |
8469 case 4: { // always coalesce | |
8470 coalesce = true; | |
8471 break; | |
8472 } | |
8473 default: | |
8474 ShouldNotReachHere(); | |
8475 } | |
8476 | |
8477 // Should the current free range be coalesced? | |
8478 // If the chunk is in a free range and either we decided to coalesce above | |
8479 // or the chunk is near the large block at the end of the heap | |
8480 // (isNearLargestChunk() returns true), then coalesce this chunk. | |
3746
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|
8481 const bool doCoalesce = inFreeRange() |
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|
8482 && (coalesce || _g->isNearLargestChunk(fc_addr)); |
0 | 8483 if (doCoalesce) { |
8484 // Coalesce the current free range on the left with the new | |
8485 // chunk on the right. If either is on a free list, | |
8486 // it must be removed from the list and stashed in the closure. | |
8487 if (freeRangeInFreeLists()) { | |
3746
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3356
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|
8488 FreeChunk* const ffc = (FreeChunk*)freeFinger(); |
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|
8489 assert(ffc->size() == pointer_delta(fc_addr, freeFinger()), |
0 | 8490 "Size of free range is inconsistent with chunk size."); |
8491 if (CMSTestInFreeList) { | |
6028
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jmasa
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6026
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|
8492 assert(_sp->verify_chunk_in_free_list(ffc), |
0 | 8493 "Chunk is not in free lists"); |
8494 } | |
8495 _sp->coalDeath(ffc->size()); | |
8496 _sp->removeFreeChunkFromFreeLists(ffc); | |
8497 set_freeRangeInFreeLists(false); | |
8498 } | |
8499 if (fcInFreeLists) { | |
8500 _sp->coalDeath(chunkSize); | |
8501 assert(fc->size() == chunkSize, | |
8502 "The chunk has the wrong size or is not in the free lists"); | |
8503 _sp->removeFreeChunkFromFreeLists(fc); | |
8504 } | |
8505 set_lastFreeRangeCoalesced(true); | |
3746
537a4053b0f9
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ysr
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3356
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|
8506 print_free_block_coalesced(fc); |
0 | 8507 } else { // not in a free range and/or should not coalesce |
8508 // Return the current free range and start a new one. | |
8509 if (inFreeRange()) { | |
8510 // In a free range but cannot coalesce with the right hand chunk. | |
8511 // Put the current free range into the free lists. | |
2132
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|
8512 flush_cur_free_chunk(freeFinger(), |
3746
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7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8513 pointer_delta(fc_addr, freeFinger())); |
0 | 8514 } |
8515 // Set up for new free range. Pass along whether the right hand | |
8516 // chunk is in the free lists. | |
8517 initialize_free_range((HeapWord*)fc, fcInFreeLists); | |
8518 } | |
8519 } | |
2132
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7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
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|
8520 |
3746
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ysr
parents:
3356
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|
8521 // Lookahead flush: |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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|
8522 // If we are tracking a free range, and this is the last chunk that |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8523 // we'll look at because its end crosses past _limit, we'll preemptively |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8524 // flush it along with any free range we may be holding on to. Note that |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
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|
8525 // this can be the case only for an already free or freshly garbage |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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|
8526 // chunk. If this block is an object, it can never straddle |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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|
8527 // over _limit. The "straddling" occurs when _limit is set at |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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|
8528 // the previous end of the space when this cycle started, and |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
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|
8529 // a subsequent heap expansion caused the previously co-terminal |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
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|
8530 // free block to be coalesced with the newly expanded portion, |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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|
8531 // thus rendering _limit a non-block-boundary making it dangerous |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8532 // for the sweeper to step over and examine. |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8533 void SweepClosure::lookahead_and_flush(FreeChunk* fc, size_t chunk_size) { |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8534 assert(inFreeRange(), "Should only be called if currently in a free range."); |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8535 HeapWord* const eob = ((HeapWord*)fc) + chunk_size; |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8536 assert(_sp->used_region().contains(eob - 1), |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8537 err_msg("eob = " PTR_FORMAT " out of bounds wrt _sp = [" PTR_FORMAT "," PTR_FORMAT ")" |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8538 " when examining fc = " PTR_FORMAT "(" SIZE_FORMAT ")", |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8539 _limit, _sp->bottom(), _sp->end(), fc, chunk_size)); |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8540 if (eob >= _limit) { |
6028
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
parents:
6026
diff
changeset
|
8541 assert(eob == _limit || fc->is_free(), "Only a free chunk should allow us to cross over the limit"); |
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8542 if (CMSTraceSweeper) { |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8543 gclog_or_tty->print_cr("_limit " PTR_FORMAT " reached or crossed by block " |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8544 "[" PTR_FORMAT "," PTR_FORMAT ") in space " |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
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|
8545 "[" PTR_FORMAT "," PTR_FORMAT ")", |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8546 _limit, fc, eob, _sp->bottom(), _sp->end()); |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
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|
8547 } |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8548 // Return the storage we are tracking back into the free lists. |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8549 if (CMSTraceSweeper) { |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
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|
8550 gclog_or_tty->print_cr("Flushing ... "); |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
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|
8551 } |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
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|
8552 assert(freeFinger() < eob, "Error"); |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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|
8553 flush_cur_free_chunk( freeFinger(), pointer_delta(eob, freeFinger())); |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
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|
8554 } |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
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|
8555 } |
537a4053b0f9
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ysr
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3356
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|
8556 |
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
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|
8557 void SweepClosure::flush_cur_free_chunk(HeapWord* chunk, size_t size) { |
0 | 8558 assert(inFreeRange(), "Should only be called if currently in a free range."); |
8559 assert(size > 0, | |
8560 "A zero sized chunk cannot be added to the free lists."); | |
8561 if (!freeRangeInFreeLists()) { | |
2132
4947ee68d19c
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ysr
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1994
diff
changeset
|
8562 if (CMSTestInFreeList) { |
0 | 8563 FreeChunk* fc = (FreeChunk*) chunk; |
6028
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7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
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6026
diff
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|
8564 fc->set_size(size); |
f69a5d43dc19
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jmasa
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6026
diff
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|
8565 assert(!_sp->verify_chunk_in_free_list(fc), |
0 | 8566 "chunk should not be in free lists yet"); |
8567 } | |
8568 if (CMSTraceSweeper) { | |
8569 gclog_or_tty->print_cr(" -- add free block 0x%x (%d) to free lists", | |
8570 chunk, size); | |
8571 } | |
8572 // A new free range is going to be starting. The current | |
8573 // free range has not been added to the free lists yet or | |
8574 // was removed so add it back. | |
8575 // If the current free range was coalesced, then the death | |
8576 // of the free range was recorded. Record a birth now. | |
8577 if (lastFreeRangeCoalesced()) { | |
8578 _sp->coalBirth(size); | |
8579 } | |
8580 _sp->addChunkAndRepairOffsetTable(chunk, size, | |
8581 lastFreeRangeCoalesced()); | |
3746
537a4053b0f9
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ysr
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3356
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|
8582 } else if (CMSTraceSweeper) { |
537a4053b0f9
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ysr
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3356
diff
changeset
|
8583 gclog_or_tty->print_cr("Already in free list: nothing to flush"); |
0 | 8584 } |
8585 set_inFreeRange(false); | |
8586 set_freeRangeInFreeLists(false); | |
8587 } | |
8588 | |
8589 // We take a break if we've been at this for a while, | |
8590 // so as to avoid monopolizing the locks involved. | |
8591 void SweepClosure::do_yield_work(HeapWord* addr) { | |
8592 // Return current free chunk being used for coalescing (if any) | |
8593 // to the appropriate freelist. After yielding, the next | |
8594 // free block encountered will start a coalescing range of | |
8595 // free blocks. If the next free block is adjacent to the | |
8596 // chunk just flushed, they will need to wait for the next | |
8597 // sweep to be coalesced. | |
8598 if (inFreeRange()) { | |
2132
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ysr
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1994
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changeset
|
8599 flush_cur_free_chunk(freeFinger(), pointer_delta(addr, freeFinger())); |
0 | 8600 } |
8601 | |
8602 // First give up the locks, then yield, then re-lock. | |
8603 // We should probably use a constructor/destructor idiom to | |
8604 // do this unlock/lock or modify the MutexUnlocker class to | |
8605 // serve our purpose. XXX | |
8606 assert_lock_strong(_bitMap->lock()); | |
8607 assert_lock_strong(_freelistLock); | |
8608 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
8609 "CMS thread should hold CMS token"); | |
8610 _bitMap->lock()->unlock(); | |
8611 _freelistLock->unlock(); | |
8612 ConcurrentMarkSweepThread::desynchronize(true); | |
8613 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
8614 _collector->stopTimer(); | |
8615 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
8616 if (PrintCMSStatistics != 0) { | |
8617 _collector->incrementYields(); | |
8618 } | |
8619 _collector->icms_wait(); | |
8620 | |
8621 // See the comment in coordinator_yield() | |
8622 for (unsigned i = 0; i < CMSYieldSleepCount && | |
8623 ConcurrentMarkSweepThread::should_yield() && | |
8624 !CMSCollector::foregroundGCIsActive(); ++i) { | |
8625 os::sleep(Thread::current(), 1, false); | |
8626 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
8627 } | |
8628 | |
8629 ConcurrentMarkSweepThread::synchronize(true); | |
8630 _freelistLock->lock(); | |
8631 _bitMap->lock()->lock_without_safepoint_check(); | |
8632 _collector->startTimer(); | |
8633 } | |
8634 | |
8635 #ifndef PRODUCT | |
8636 // This is actually very useful in a product build if it can | |
8637 // be called from the debugger. Compile it into the product | |
8638 // as needed. | |
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8639 bool debug_verify_chunk_in_free_list(FreeChunk* fc) { |
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8640 return debug_cms_space->verify_chunk_in_free_list(fc); |
0 | 8641 } |
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8642 #endif |
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8643 |
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8644 void SweepClosure::print_free_block_coalesced(FreeChunk* fc) const { |
0 | 8645 if (CMSTraceSweeper) { |
3746
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8646 gclog_or_tty->print_cr("Sweep:coal_free_blk " PTR_FORMAT " (" SIZE_FORMAT ")", |
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8647 fc, fc->size()); |
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8648 } |
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8649 } |
0 | 8650 |
8651 // CMSIsAliveClosure | |
8652 bool CMSIsAliveClosure::do_object_b(oop obj) { | |
8653 HeapWord* addr = (HeapWord*)obj; | |
8654 return addr != NULL && | |
8655 (!_span.contains(addr) || _bit_map->isMarked(addr)); | |
8656 } | |
8657 | |
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8658 |
935 | 8659 CMSKeepAliveClosure::CMSKeepAliveClosure( CMSCollector* collector, |
8660 MemRegion span, | |
8661 CMSBitMap* bit_map, CMSMarkStack* mark_stack, | |
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8662 bool cpc): |
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8663 _collector(collector), |
935 | 8664 _span(span), |
8665 _bit_map(bit_map), | |
8666 _mark_stack(mark_stack), | |
8667 _concurrent_precleaning(cpc) { | |
8668 assert(!_span.is_empty(), "Empty span could spell trouble"); | |
8669 } | |
8670 | |
8671 | |
0 | 8672 // CMSKeepAliveClosure: the serial version |
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8673 void CMSKeepAliveClosure::do_oop(oop obj) { |
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8674 HeapWord* addr = (HeapWord*)obj; |
0 | 8675 if (_span.contains(addr) && |
8676 !_bit_map->isMarked(addr)) { | |
8677 _bit_map->mark(addr); | |
8678 bool simulate_overflow = false; | |
8679 NOT_PRODUCT( | |
8680 if (CMSMarkStackOverflowALot && | |
8681 _collector->simulate_overflow()) { | |
8682 // simulate a stack overflow | |
8683 simulate_overflow = true; | |
8684 } | |
8685 ) | |
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8686 if (simulate_overflow || !_mark_stack->push(obj)) { |
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8687 if (_concurrent_precleaning) { |
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8688 // We dirty the overflown object and let the remark |
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8689 // phase deal with it. |
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8690 assert(_collector->overflow_list_is_empty(), "Error"); |
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8691 // In the case of object arrays, we need to dirty all of |
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8692 // the cards that the object spans. No locking or atomics |
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8693 // are needed since no one else can be mutating the mod union |
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8694 // table. |
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8695 if (obj->is_objArray()) { |
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8696 size_t sz = obj->size(); |
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8697 HeapWord* end_card_addr = |
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8698 (HeapWord*)round_to((intptr_t)(addr+sz), CardTableModRefBS::card_size); |
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8699 MemRegion redirty_range = MemRegion(addr, end_card_addr); |
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8700 assert(!redirty_range.is_empty(), "Arithmetical tautology"); |
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8701 _collector->_modUnionTable.mark_range(redirty_range); |
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8702 } else { |
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8703 _collector->_modUnionTable.mark(addr); |
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8704 } |
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8705 _collector->_ser_kac_preclean_ovflw++; |
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8706 } else { |
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8707 _collector->push_on_overflow_list(obj); |
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8708 _collector->_ser_kac_ovflw++; |
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8709 } |
0 | 8710 } |
8711 } | |
8712 } | |
8713 | |
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8714 void CMSKeepAliveClosure::do_oop(oop* p) { CMSKeepAliveClosure::do_oop_work(p); } |
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8715 void CMSKeepAliveClosure::do_oop(narrowOop* p) { CMSKeepAliveClosure::do_oop_work(p); } |
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8716 |
0 | 8717 // CMSParKeepAliveClosure: a parallel version of the above. |
8718 // The work queues are private to each closure (thread), | |
8719 // but (may be) available for stealing by other threads. | |
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8720 void CMSParKeepAliveClosure::do_oop(oop obj) { |
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8721 HeapWord* addr = (HeapWord*)obj; |
0 | 8722 if (_span.contains(addr) && |
8723 !_bit_map->isMarked(addr)) { | |
8724 // In general, during recursive tracing, several threads | |
8725 // may be concurrently getting here; the first one to | |
8726 // "tag" it, claims it. | |
8727 if (_bit_map->par_mark(addr)) { | |
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8728 bool res = _work_queue->push(obj); |
0 | 8729 assert(res, "Low water mark should be much less than capacity"); |
8730 // Do a recursive trim in the hope that this will keep | |
8731 // stack usage lower, but leave some oops for potential stealers | |
8732 trim_queue(_low_water_mark); | |
8733 } // Else, another thread got there first | |
8734 } | |
8735 } | |
8736 | |
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8737 void CMSParKeepAliveClosure::do_oop(oop* p) { CMSParKeepAliveClosure::do_oop_work(p); } |
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8738 void CMSParKeepAliveClosure::do_oop(narrowOop* p) { CMSParKeepAliveClosure::do_oop_work(p); } |
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8739 |
0 | 8740 void CMSParKeepAliveClosure::trim_queue(uint max) { |
8741 while (_work_queue->size() > max) { | |
8742 oop new_oop; | |
8743 if (_work_queue->pop_local(new_oop)) { | |
8744 assert(new_oop != NULL && new_oop->is_oop(), "Expected an oop"); | |
8745 assert(_bit_map->isMarked((HeapWord*)new_oop), | |
8746 "no white objects on this stack!"); | |
8747 assert(_span.contains((HeapWord*)new_oop), "Out of bounds oop"); | |
8748 // iterate over the oops in this oop, marking and pushing | |
8749 // the ones in CMS heap (i.e. in _span). | |
8750 new_oop->oop_iterate(&_mark_and_push); | |
8751 } | |
8752 } | |
8753 } | |
8754 | |
935 | 8755 CMSInnerParMarkAndPushClosure::CMSInnerParMarkAndPushClosure( |
8756 CMSCollector* collector, | |
8757 MemRegion span, CMSBitMap* bit_map, | |
8758 OopTaskQueue* work_queue): | |
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8759 _collector(collector), |
935 | 8760 _span(span), |
8761 _bit_map(bit_map), | |
8762 _work_queue(work_queue) { } | |
8763 | |
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8764 void CMSInnerParMarkAndPushClosure::do_oop(oop obj) { |
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8765 HeapWord* addr = (HeapWord*)obj; |
0 | 8766 if (_span.contains(addr) && |
8767 !_bit_map->isMarked(addr)) { | |
8768 if (_bit_map->par_mark(addr)) { | |
8769 bool simulate_overflow = false; | |
8770 NOT_PRODUCT( | |
8771 if (CMSMarkStackOverflowALot && | |
8772 _collector->par_simulate_overflow()) { | |
8773 // simulate a stack overflow | |
8774 simulate_overflow = true; | |
8775 } | |
8776 ) | |
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8777 if (simulate_overflow || !_work_queue->push(obj)) { |
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8778 _collector->par_push_on_overflow_list(obj); |
0 | 8779 _collector->_par_kac_ovflw++; |
8780 } | |
8781 } // Else another thread got there already | |
8782 } | |
8783 } | |
8784 | |
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8785 void CMSInnerParMarkAndPushClosure::do_oop(oop* p) { CMSInnerParMarkAndPushClosure::do_oop_work(p); } |
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8786 void CMSInnerParMarkAndPushClosure::do_oop(narrowOop* p) { CMSInnerParMarkAndPushClosure::do_oop_work(p); } |
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8787 |
0 | 8788 ////////////////////////////////////////////////////////////////// |
8789 // CMSExpansionCause ///////////////////////////// | |
8790 ////////////////////////////////////////////////////////////////// | |
8791 const char* CMSExpansionCause::to_string(CMSExpansionCause::Cause cause) { | |
8792 switch (cause) { | |
8793 case _no_expansion: | |
8794 return "No expansion"; | |
8795 case _satisfy_free_ratio: | |
8796 return "Free ratio"; | |
8797 case _satisfy_promotion: | |
8798 return "Satisfy promotion"; | |
8799 case _satisfy_allocation: | |
8800 return "allocation"; | |
8801 case _allocate_par_lab: | |
8802 return "Par LAB"; | |
8803 case _allocate_par_spooling_space: | |
8804 return "Par Spooling Space"; | |
8805 case _adaptive_size_policy: | |
8806 return "Ergonomics"; | |
8807 default: | |
8808 return "unknown"; | |
8809 } | |
8810 } | |
8811 | |
8812 void CMSDrainMarkingStackClosure::do_void() { | |
8813 // the max number to take from overflow list at a time | |
8814 const size_t num = _mark_stack->capacity()/4; | |
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8815 assert(!_concurrent_precleaning || _collector->overflow_list_is_empty(), |
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8816 "Overflow list should be NULL during concurrent phases"); |
0 | 8817 while (!_mark_stack->isEmpty() || |
8818 // if stack is empty, check the overflow list | |
8819 _collector->take_from_overflow_list(num, _mark_stack)) { | |
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8820 oop obj = _mark_stack->pop(); |
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8821 HeapWord* addr = (HeapWord*)obj; |
0 | 8822 assert(_span.contains(addr), "Should be within span"); |
8823 assert(_bit_map->isMarked(addr), "Should be marked"); | |
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8824 assert(obj->is_oop(), "Should be an oop"); |
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8825 obj->oop_iterate(_keep_alive); |
0 | 8826 } |
8827 } | |
8828 | |
8829 void CMSParDrainMarkingStackClosure::do_void() { | |
8830 // drain queue | |
8831 trim_queue(0); | |
8832 } | |
8833 | |
8834 // Trim our work_queue so its length is below max at return | |
8835 void CMSParDrainMarkingStackClosure::trim_queue(uint max) { | |
8836 while (_work_queue->size() > max) { | |
8837 oop new_oop; | |
8838 if (_work_queue->pop_local(new_oop)) { | |
8839 assert(new_oop->is_oop(), "Expected an oop"); | |
8840 assert(_bit_map->isMarked((HeapWord*)new_oop), | |
8841 "no white objects on this stack!"); | |
8842 assert(_span.contains((HeapWord*)new_oop), "Out of bounds oop"); | |
8843 // iterate over the oops in this oop, marking and pushing | |
8844 // the ones in CMS heap (i.e. in _span). | |
8845 new_oop->oop_iterate(&_mark_and_push); | |
8846 } | |
8847 } | |
8848 } | |
8849 | |
8850 //////////////////////////////////////////////////////////////////// | |
8851 // Support for Marking Stack Overflow list handling and related code | |
8852 //////////////////////////////////////////////////////////////////// | |
8853 // Much of the following code is similar in shape and spirit to the | |
8854 // code used in ParNewGC. We should try and share that code | |
8855 // as much as possible in the future. | |
8856 | |
8857 #ifndef PRODUCT | |
8858 // Debugging support for CMSStackOverflowALot | |
8859 | |
8860 // It's OK to call this multi-threaded; the worst thing | |
8861 // that can happen is that we'll get a bunch of closely | |
8862 // spaced simulated oveflows, but that's OK, in fact | |
8863 // probably good as it would exercise the overflow code | |
8864 // under contention. | |
8865 bool CMSCollector::simulate_overflow() { | |
8866 if (_overflow_counter-- <= 0) { // just being defensive | |
8867 _overflow_counter = CMSMarkStackOverflowInterval; | |
8868 return true; | |
8869 } else { | |
8870 return false; | |
8871 } | |
8872 } | |
8873 | |
8874 bool CMSCollector::par_simulate_overflow() { | |
8875 return simulate_overflow(); | |
8876 } | |
8877 #endif | |
8878 | |
8879 // Single-threaded | |
8880 bool CMSCollector::take_from_overflow_list(size_t num, CMSMarkStack* stack) { | |
8881 assert(stack->isEmpty(), "Expected precondition"); | |
8882 assert(stack->capacity() > num, "Shouldn't bite more than can chew"); | |
8883 size_t i = num; | |
8884 oop cur = _overflow_list; | |
8885 const markOop proto = markOopDesc::prototype(); | |
534 | 8886 NOT_PRODUCT(ssize_t n = 0;) |
0 | 8887 for (oop next; i > 0 && cur != NULL; cur = next, i--) { |
8888 next = oop(cur->mark()); | |
8889 cur->set_mark(proto); // until proven otherwise | |
8890 assert(cur->is_oop(), "Should be an oop"); | |
8891 bool res = stack->push(cur); | |
8892 assert(res, "Bit off more than can chew?"); | |
8893 NOT_PRODUCT(n++;) | |
8894 } | |
8895 _overflow_list = cur; | |
8896 #ifndef PRODUCT | |
8897 assert(_num_par_pushes >= n, "Too many pops?"); | |
8898 _num_par_pushes -=n; | |
8899 #endif | |
8900 return !stack->isEmpty(); | |
8901 } | |
8902 | |
534 | 8903 #define BUSY (oop(0x1aff1aff)) |
8904 // (MT-safe) Get a prefix of at most "num" from the list. | |
8905 // The overflow list is chained through the mark word of | |
8906 // each object in the list. We fetch the entire list, | |
8907 // break off a prefix of the right size and return the | |
8908 // remainder. If other threads try to take objects from | |
8909 // the overflow list at that time, they will wait for | |
8910 // some time to see if data becomes available. If (and | |
8911 // only if) another thread places one or more object(s) | |
8912 // on the global list before we have returned the suffix | |
8913 // to the global list, we will walk down our local list | |
8914 // to find its end and append the global list to | |
8915 // our suffix before returning it. This suffix walk can | |
8916 // prove to be expensive (quadratic in the amount of traffic) | |
8917 // when there are many objects in the overflow list and | |
8918 // there is much producer-consumer contention on the list. | |
8919 // *NOTE*: The overflow list manipulation code here and | |
8920 // in ParNewGeneration:: are very similar in shape, | |
8921 // except that in the ParNew case we use the old (from/eden) | |
8922 // copy of the object to thread the list via its klass word. | |
8923 // Because of the common code, if you make any changes in | |
8924 // the code below, please check the ParNew version to see if | |
8925 // similar changes might be needed. | |
8926 // CR 6797058 has been filed to consolidate the common code. | |
0 | 8927 bool CMSCollector::par_take_from_overflow_list(size_t num, |
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8928 OopTaskQueue* work_q, |
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8929 int no_of_gc_threads) { |
534 | 8930 assert(work_q->size() == 0, "First empty local work queue"); |
0 | 8931 assert(num < work_q->max_elems(), "Can't bite more than we can chew"); |
8932 if (_overflow_list == NULL) { | |
8933 return false; | |
8934 } | |
8935 // Grab the entire list; we'll put back a suffix | |
534 | 8936 oop prefix = (oop)Atomic::xchg_ptr(BUSY, &_overflow_list); |
8937 Thread* tid = Thread::current(); | |
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8938 // Before "no_of_gc_threads" was introduced CMSOverflowSpinCount was |
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8939 // set to ParallelGCThreads. |
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8940 size_t CMSOverflowSpinCount = (size_t) no_of_gc_threads; // was ParallelGCThreads; |
534 | 8941 size_t sleep_time_millis = MAX2((size_t)1, num/100); |
8942 // If the list is busy, we spin for a short while, | |
8943 // sleeping between attempts to get the list. | |
8944 for (size_t spin = 0; prefix == BUSY && spin < CMSOverflowSpinCount; spin++) { | |
8945 os::sleep(tid, sleep_time_millis, false); | |
8946 if (_overflow_list == NULL) { | |
8947 // Nothing left to take | |
8948 return false; | |
8949 } else if (_overflow_list != BUSY) { | |
8950 // Try and grab the prefix | |
8951 prefix = (oop)Atomic::xchg_ptr(BUSY, &_overflow_list); | |
8952 } | |
8953 } | |
8954 // If the list was found to be empty, or we spun long | |
8955 // enough, we give up and return empty-handed. If we leave | |
8956 // the list in the BUSY state below, it must be the case that | |
8957 // some other thread holds the overflow list and will set it | |
8958 // to a non-BUSY state in the future. | |
8959 if (prefix == NULL || prefix == BUSY) { | |
8960 // Nothing to take or waited long enough | |
8961 if (prefix == NULL) { | |
8962 // Write back the NULL in case we overwrote it with BUSY above | |
8963 // and it is still the same value. | |
8964 (void) Atomic::cmpxchg_ptr(NULL, &_overflow_list, BUSY); | |
8965 } | |
8966 return false; | |
8967 } | |
8968 assert(prefix != NULL && prefix != BUSY, "Error"); | |
0 | 8969 size_t i = num; |
8970 oop cur = prefix; | |
534 | 8971 // Walk down the first "num" objects, unless we reach the end. |
0 | 8972 for (; i > 1 && cur->mark() != NULL; cur = oop(cur->mark()), i--); |
534 | 8973 if (cur->mark() == NULL) { |
8974 // We have "num" or fewer elements in the list, so there | |
8975 // is nothing to return to the global list. | |
8976 // Write back the NULL in lieu of the BUSY we wrote | |
8977 // above, if it is still the same value. | |
8978 if (_overflow_list == BUSY) { | |
8979 (void) Atomic::cmpxchg_ptr(NULL, &_overflow_list, BUSY); | |
8980 } | |
8981 } else { | |
8982 // Chop off the suffix and rerturn it to the global list. | |
8983 assert(cur->mark() != BUSY, "Error"); | |
0 | 8984 oop suffix_head = cur->mark(); // suffix will be put back on global list |
8985 cur->set_mark(NULL); // break off suffix | |
534 | 8986 // It's possible that the list is still in the empty(busy) state |
8987 // we left it in a short while ago; in that case we may be | |
8988 // able to place back the suffix without incurring the cost | |
8989 // of a walk down the list. | |
0 | 8990 oop observed_overflow_list = _overflow_list; |
534 | 8991 oop cur_overflow_list = observed_overflow_list; |
8992 bool attached = false; | |
8993 while (observed_overflow_list == BUSY || observed_overflow_list == NULL) { | |
0 | 8994 observed_overflow_list = |
534 | 8995 (oop) Atomic::cmpxchg_ptr(suffix_head, &_overflow_list, cur_overflow_list); |
8996 if (cur_overflow_list == observed_overflow_list) { | |
8997 attached = true; | |
8998 break; | |
8999 } else cur_overflow_list = observed_overflow_list; | |
9000 } | |
9001 if (!attached) { | |
9002 // Too bad, someone else sneaked in (at least) an element; we'll need | |
9003 // to do a splice. Find tail of suffix so we can prepend suffix to global | |
9004 // list. | |
9005 for (cur = suffix_head; cur->mark() != NULL; cur = (oop)(cur->mark())); | |
9006 oop suffix_tail = cur; | |
9007 assert(suffix_tail != NULL && suffix_tail->mark() == NULL, | |
9008 "Tautology"); | |
9009 observed_overflow_list = _overflow_list; | |
9010 do { | |
9011 cur_overflow_list = observed_overflow_list; | |
9012 if (cur_overflow_list != BUSY) { | |
9013 // Do the splice ... | |
9014 suffix_tail->set_mark(markOop(cur_overflow_list)); | |
9015 } else { // cur_overflow_list == BUSY | |
9016 suffix_tail->set_mark(NULL); | |
9017 } | |
9018 // ... and try to place spliced list back on overflow_list ... | |
9019 observed_overflow_list = | |
9020 (oop) Atomic::cmpxchg_ptr(suffix_head, &_overflow_list, cur_overflow_list); | |
9021 } while (cur_overflow_list != observed_overflow_list); | |
9022 // ... until we have succeeded in doing so. | |
9023 } | |
0 | 9024 } |
9025 | |
9026 // Push the prefix elements on work_q | |
9027 assert(prefix != NULL, "control point invariant"); | |
9028 const markOop proto = markOopDesc::prototype(); | |
9029 oop next; | |
534 | 9030 NOT_PRODUCT(ssize_t n = 0;) |
0 | 9031 for (cur = prefix; cur != NULL; cur = next) { |
9032 next = oop(cur->mark()); | |
9033 cur->set_mark(proto); // until proven otherwise | |
9034 assert(cur->is_oop(), "Should be an oop"); | |
9035 bool res = work_q->push(cur); | |
9036 assert(res, "Bit off more than we can chew?"); | |
9037 NOT_PRODUCT(n++;) | |
9038 } | |
9039 #ifndef PRODUCT | |
9040 assert(_num_par_pushes >= n, "Too many pops?"); | |
9041 Atomic::add_ptr(-(intptr_t)n, &_num_par_pushes); | |
9042 #endif | |
9043 return true; | |
9044 } | |
9045 | |
9046 // Single-threaded | |
9047 void CMSCollector::push_on_overflow_list(oop p) { | |
9048 NOT_PRODUCT(_num_par_pushes++;) | |
9049 assert(p->is_oop(), "Not an oop"); | |
9050 preserve_mark_if_necessary(p); | |
9051 p->set_mark((markOop)_overflow_list); | |
9052 _overflow_list = p; | |
9053 } | |
9054 | |
9055 // Multi-threaded; use CAS to prepend to overflow list | |
9056 void CMSCollector::par_push_on_overflow_list(oop p) { | |
9057 NOT_PRODUCT(Atomic::inc_ptr(&_num_par_pushes);) | |
9058 assert(p->is_oop(), "Not an oop"); | |
9059 par_preserve_mark_if_necessary(p); | |
9060 oop observed_overflow_list = _overflow_list; | |
9061 oop cur_overflow_list; | |
9062 do { | |
9063 cur_overflow_list = observed_overflow_list; | |
534 | 9064 if (cur_overflow_list != BUSY) { |
9065 p->set_mark(markOop(cur_overflow_list)); | |
9066 } else { | |
9067 p->set_mark(NULL); | |
9068 } | |
0 | 9069 observed_overflow_list = |
9070 (oop) Atomic::cmpxchg_ptr(p, &_overflow_list, cur_overflow_list); | |
9071 } while (cur_overflow_list != observed_overflow_list); | |
9072 } | |
534 | 9073 #undef BUSY |
0 | 9074 |
9075 // Single threaded | |
9076 // General Note on GrowableArray: pushes may silently fail | |
9077 // because we are (temporarily) out of C-heap for expanding | |
9078 // the stack. The problem is quite ubiquitous and affects | |
9079 // a lot of code in the JVM. The prudent thing for GrowableArray | |
9080 // to do (for now) is to exit with an error. However, that may | |
9081 // be too draconian in some cases because the caller may be | |
534 | 9082 // able to recover without much harm. For such cases, we |
0 | 9083 // should probably introduce a "soft_push" method which returns |
9084 // an indication of success or failure with the assumption that | |
9085 // the caller may be able to recover from a failure; code in | |
9086 // the VM can then be changed, incrementally, to deal with such | |
9087 // failures where possible, thus, incrementally hardening the VM | |
9088 // in such low resource situations. | |
9089 void CMSCollector::preserve_mark_work(oop p, markOop m) { | |
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9090 _preserved_oop_stack.push(p); |
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9091 _preserved_mark_stack.push(m); |
0 | 9092 assert(m == p->mark(), "Mark word changed"); |
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9093 assert(_preserved_oop_stack.size() == _preserved_mark_stack.size(), |
0 | 9094 "bijection"); |
9095 } | |
9096 | |
9097 // Single threaded | |
9098 void CMSCollector::preserve_mark_if_necessary(oop p) { | |
9099 markOop m = p->mark(); | |
9100 if (m->must_be_preserved(p)) { | |
9101 preserve_mark_work(p, m); | |
9102 } | |
9103 } | |
9104 | |
9105 void CMSCollector::par_preserve_mark_if_necessary(oop p) { | |
9106 markOop m = p->mark(); | |
9107 if (m->must_be_preserved(p)) { | |
9108 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); | |
9109 // Even though we read the mark word without holding | |
9110 // the lock, we are assured that it will not change | |
9111 // because we "own" this oop, so no other thread can | |
9112 // be trying to push it on the overflow list; see | |
9113 // the assertion in preserve_mark_work() that checks | |
9114 // that m == p->mark(). | |
9115 preserve_mark_work(p, m); | |
9116 } | |
9117 } | |
9118 | |
9119 // We should be able to do this multi-threaded, | |
9120 // a chunk of stack being a task (this is | |
9121 // correct because each oop only ever appears | |
9122 // once in the overflow list. However, it's | |
9123 // not very easy to completely overlap this with | |
9124 // other operations, so will generally not be done | |
9125 // until all work's been completed. Because we | |
9126 // expect the preserved oop stack (set) to be small, | |
9127 // it's probably fine to do this single-threaded. | |
9128 // We can explore cleverer concurrent/overlapped/parallel | |
9129 // processing of preserved marks if we feel the | |
9130 // need for this in the future. Stack overflow should | |
9131 // be so rare in practice and, when it happens, its | |
9132 // effect on performance so great that this will | |
9133 // likely just be in the noise anyway. | |
9134 void CMSCollector::restore_preserved_marks_if_any() { | |
9135 assert(SafepointSynchronize::is_at_safepoint(), | |
9136 "world should be stopped"); | |
9137 assert(Thread::current()->is_ConcurrentGC_thread() || | |
9138 Thread::current()->is_VM_thread(), | |
9139 "should be single-threaded"); | |
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9140 assert(_preserved_oop_stack.size() == _preserved_mark_stack.size(), |
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9141 "bijection"); |
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9142 |
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9143 while (!_preserved_oop_stack.is_empty()) { |
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9144 oop p = _preserved_oop_stack.pop(); |
0 | 9145 assert(p->is_oop(), "Should be an oop"); |
9146 assert(_span.contains(p), "oop should be in _span"); | |
9147 assert(p->mark() == markOopDesc::prototype(), | |
9148 "Set when taken from overflow list"); | |
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9149 markOop m = _preserved_mark_stack.pop(); |
0 | 9150 p->set_mark(m); |
9151 } | |
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9152 assert(_preserved_mark_stack.is_empty() && _preserved_oop_stack.is_empty(), |
0 | 9153 "stacks were cleared above"); |
9154 } | |
9155 | |
9156 #ifndef PRODUCT | |
9157 bool CMSCollector::no_preserved_marks() const { | |
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9158 return _preserved_mark_stack.is_empty() && _preserved_oop_stack.is_empty(); |
0 | 9159 } |
9160 #endif | |
9161 | |
9162 CMSAdaptiveSizePolicy* ASConcurrentMarkSweepGeneration::cms_size_policy() const | |
9163 { | |
9164 GenCollectedHeap* gch = (GenCollectedHeap*) GenCollectedHeap::heap(); | |
9165 CMSAdaptiveSizePolicy* size_policy = | |
9166 (CMSAdaptiveSizePolicy*) gch->gen_policy()->size_policy(); | |
9167 assert(size_policy->is_gc_cms_adaptive_size_policy(), | |
9168 "Wrong type for size policy"); | |
9169 return size_policy; | |
9170 } | |
9171 | |
9172 void ASConcurrentMarkSweepGeneration::resize(size_t cur_promo_size, | |
9173 size_t desired_promo_size) { | |
9174 if (cur_promo_size < desired_promo_size) { | |
9175 size_t expand_bytes = desired_promo_size - cur_promo_size; | |
9176 if (PrintAdaptiveSizePolicy && Verbose) { | |
9177 gclog_or_tty->print_cr(" ASConcurrentMarkSweepGeneration::resize " | |
9178 "Expanding tenured generation by " SIZE_FORMAT " (bytes)", | |
9179 expand_bytes); | |
9180 } | |
9181 expand(expand_bytes, | |
9182 MinHeapDeltaBytes, | |
9183 CMSExpansionCause::_adaptive_size_policy); | |
9184 } else if (desired_promo_size < cur_promo_size) { | |
9185 size_t shrink_bytes = cur_promo_size - desired_promo_size; | |
9186 if (PrintAdaptiveSizePolicy && Verbose) { | |
9187 gclog_or_tty->print_cr(" ASConcurrentMarkSweepGeneration::resize " | |
9188 "Shrinking tenured generation by " SIZE_FORMAT " (bytes)", | |
9189 shrink_bytes); | |
9190 } | |
9191 shrink(shrink_bytes); | |
9192 } | |
9193 } | |
9194 | |
9195 CMSGCAdaptivePolicyCounters* ASConcurrentMarkSweepGeneration::gc_adaptive_policy_counters() { | |
9196 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
9197 CMSGCAdaptivePolicyCounters* counters = | |
9198 (CMSGCAdaptivePolicyCounters*) gch->collector_policy()->counters(); | |
9199 assert(counters->kind() == GCPolicyCounters::CMSGCAdaptivePolicyCountersKind, | |
9200 "Wrong kind of counters"); | |
9201 return counters; | |
9202 } | |
9203 | |
9204 | |
9205 void ASConcurrentMarkSweepGeneration::update_counters() { | |
9206 if (UsePerfData) { | |
9207 _space_counters->update_all(); | |
9208 _gen_counters->update_all(); | |
9209 CMSGCAdaptivePolicyCounters* counters = gc_adaptive_policy_counters(); | |
9210 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
9211 CMSGCStats* gc_stats_l = (CMSGCStats*) gc_stats(); | |
9212 assert(gc_stats_l->kind() == GCStats::CMSGCStatsKind, | |
9213 "Wrong gc statistics type"); | |
9214 counters->update_counters(gc_stats_l); | |
9215 } | |
9216 } | |
9217 | |
9218 void ASConcurrentMarkSweepGeneration::update_counters(size_t used) { | |
9219 if (UsePerfData) { | |
9220 _space_counters->update_used(used); | |
9221 _space_counters->update_capacity(); | |
9222 _gen_counters->update_all(); | |
9223 | |
9224 CMSGCAdaptivePolicyCounters* counters = gc_adaptive_policy_counters(); | |
9225 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
9226 CMSGCStats* gc_stats_l = (CMSGCStats*) gc_stats(); | |
9227 assert(gc_stats_l->kind() == GCStats::CMSGCStatsKind, | |
9228 "Wrong gc statistics type"); | |
9229 counters->update_counters(gc_stats_l); | |
9230 } | |
9231 } | |
9232 | |
9233 void ASConcurrentMarkSweepGeneration::shrink_by(size_t desired_bytes) { | |
9234 assert_locked_or_safepoint(Heap_lock); | |
9235 assert_lock_strong(freelistLock()); | |
9236 HeapWord* old_end = _cmsSpace->end(); | |
9237 HeapWord* unallocated_start = _cmsSpace->unallocated_block(); | |
9238 assert(old_end >= unallocated_start, "Miscalculation of unallocated_start"); | |
9239 FreeChunk* chunk_at_end = find_chunk_at_end(); | |
9240 if (chunk_at_end == NULL) { | |
9241 // No room to shrink | |
9242 if (PrintGCDetails && Verbose) { | |
9243 gclog_or_tty->print_cr("No room to shrink: old_end " | |
9244 PTR_FORMAT " unallocated_start " PTR_FORMAT | |
9245 " chunk_at_end " PTR_FORMAT, | |
9246 old_end, unallocated_start, chunk_at_end); | |
9247 } | |
9248 return; | |
9249 } else { | |
9250 | |
9251 // Find the chunk at the end of the space and determine | |
9252 // how much it can be shrunk. | |
9253 size_t shrinkable_size_in_bytes = chunk_at_end->size(); | |
9254 size_t aligned_shrinkable_size_in_bytes = | |
9255 align_size_down(shrinkable_size_in_bytes, os::vm_page_size()); | |
6885 | 9256 assert(unallocated_start <= (HeapWord*) chunk_at_end->end(), |
0 | 9257 "Inconsistent chunk at end of space"); |
9258 size_t bytes = MIN2(desired_bytes, aligned_shrinkable_size_in_bytes); | |
9259 size_t word_size_before = heap_word_size(_virtual_space.committed_size()); | |
9260 | |
9261 // Shrink the underlying space | |
9262 _virtual_space.shrink_by(bytes); | |
9263 if (PrintGCDetails && Verbose) { | |
9264 gclog_or_tty->print_cr("ConcurrentMarkSweepGeneration::shrink_by:" | |
9265 " desired_bytes " SIZE_FORMAT | |
9266 " shrinkable_size_in_bytes " SIZE_FORMAT | |
9267 " aligned_shrinkable_size_in_bytes " SIZE_FORMAT | |
9268 " bytes " SIZE_FORMAT, | |
9269 desired_bytes, shrinkable_size_in_bytes, | |
9270 aligned_shrinkable_size_in_bytes, bytes); | |
9271 gclog_or_tty->print_cr(" old_end " SIZE_FORMAT | |
9272 " unallocated_start " SIZE_FORMAT, | |
9273 old_end, unallocated_start); | |
9274 } | |
9275 | |
9276 // If the space did shrink (shrinking is not guaranteed), | |
9277 // shrink the chunk at the end by the appropriate amount. | |
9278 if (((HeapWord*)_virtual_space.high()) < old_end) { | |
9279 size_t new_word_size = | |
9280 heap_word_size(_virtual_space.committed_size()); | |
9281 | |
9282 // Have to remove the chunk from the dictionary because it is changing | |
9283 // size and might be someplace elsewhere in the dictionary. | |
9284 | |
9285 // Get the chunk at end, shrink it, and put it | |
9286 // back. | |
9287 _cmsSpace->removeChunkFromDictionary(chunk_at_end); | |
9288 size_t word_size_change = word_size_before - new_word_size; | |
9289 size_t chunk_at_end_old_size = chunk_at_end->size(); | |
9290 assert(chunk_at_end_old_size >= word_size_change, | |
9291 "Shrink is too large"); | |
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9292 chunk_at_end->set_size(chunk_at_end_old_size - |
0 | 9293 word_size_change); |
9294 _cmsSpace->freed((HeapWord*) chunk_at_end->end(), | |
9295 word_size_change); | |
9296 | |
9297 _cmsSpace->returnChunkToDictionary(chunk_at_end); | |
9298 | |
9299 MemRegion mr(_cmsSpace->bottom(), new_word_size); | |
9300 _bts->resize(new_word_size); // resize the block offset shared array | |
9301 Universe::heap()->barrier_set()->resize_covered_region(mr); | |
9302 _cmsSpace->assert_locked(); | |
9303 _cmsSpace->set_end((HeapWord*)_virtual_space.high()); | |
9304 | |
9305 NOT_PRODUCT(_cmsSpace->dictionary()->verify()); | |
9306 | |
9307 // update the space and generation capacity counters | |
9308 if (UsePerfData) { | |
9309 _space_counters->update_capacity(); | |
9310 _gen_counters->update_all(); | |
9311 } | |
9312 | |
9313 if (Verbose && PrintGCDetails) { | |
9314 size_t new_mem_size = _virtual_space.committed_size(); | |
9315 size_t old_mem_size = new_mem_size + bytes; | |
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9316 gclog_or_tty->print_cr("Shrinking %s from " SIZE_FORMAT "K by " SIZE_FORMAT "K to " SIZE_FORMAT "K", |
0 | 9317 name(), old_mem_size/K, bytes/K, new_mem_size/K); |
9318 } | |
9319 } | |
9320 | |
9321 assert(_cmsSpace->unallocated_block() <= _cmsSpace->end(), | |
9322 "Inconsistency at end of space"); | |
6885 | 9323 assert(chunk_at_end->end() == (uintptr_t*) _cmsSpace->end(), |
0 | 9324 "Shrinking is inconsistent"); |
9325 return; | |
9326 } | |
9327 } | |
9328 | |
9329 // Transfer some number of overflown objects to usual marking | |
9330 // stack. Return true if some objects were transferred. | |
9331 bool MarkRefsIntoAndScanClosure::take_from_overflow_list() { | |
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9332 size_t num = MIN2((size_t)(_mark_stack->capacity() - _mark_stack->length())/4, |
0 | 9333 (size_t)ParGCDesiredObjsFromOverflowList); |
9334 | |
9335 bool res = _collector->take_from_overflow_list(num, _mark_stack); | |
9336 assert(_collector->overflow_list_is_empty() || res, | |
9337 "If list is not empty, we should have taken something"); | |
9338 assert(!res || !_mark_stack->isEmpty(), | |
9339 "If we took something, it should now be on our stack"); | |
9340 return res; | |
9341 } | |
9342 | |
9343 size_t MarkDeadObjectsClosure::do_blk(HeapWord* addr) { | |
9344 size_t res = _sp->block_size_no_stall(addr, _collector); | |
9345 if (_sp->block_is_obj(addr)) { | |
9346 if (_live_bit_map->isMarked(addr)) { | |
9347 // It can't have been dead in a previous cycle | |
9348 guarantee(!_dead_bit_map->isMarked(addr), "No resurrection!"); | |
9349 } else { | |
9350 _dead_bit_map->mark(addr); // mark the dead object | |
9351 } | |
9352 } | |
2226
c5a923563727
6912621: iCMS: Error: assert(_markBitMap.isMarked(addr + 1),"Missing Printezis bit?")
ysr
parents:
2177
diff
changeset
|
9353 // Could be 0, if the block size could not be computed without stalling. |
0 | 9354 return res; |
9355 } | |
1703
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9356 |
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
parents:
3293
diff
changeset
|
9357 TraceCMSMemoryManagerStats::TraceCMSMemoryManagerStats(CMSCollector::CollectorState phase, GCCause::Cause cause): TraceMemoryManagerStats() { |
1703
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9358 |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9359 switch (phase) { |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9360 case CMSCollector::InitialMarking: |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9361 initialize(true /* fullGC */ , |
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
parents:
3293
diff
changeset
|
9362 cause /* cause of the GC */, |
1703
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9363 true /* recordGCBeginTime */, |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9364 true /* recordPreGCUsage */, |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9365 false /* recordPeakUsage */, |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9366 false /* recordPostGCusage */, |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9367 true /* recordAccumulatedGCTime */, |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9368 false /* recordGCEndTime */, |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9369 false /* countCollection */ ); |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9370 break; |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9371 |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9372 case CMSCollector::FinalMarking: |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9373 initialize(true /* fullGC */ , |
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
parents:
3293
diff
changeset
|
9374 cause /* cause of the GC */, |
1703
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9375 false /* recordGCBeginTime */, |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9376 false /* recordPreGCUsage */, |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9377 false /* recordPeakUsage */, |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9378 false /* recordPostGCusage */, |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9379 true /* recordAccumulatedGCTime */, |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9380 false /* recordGCEndTime */, |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9381 false /* countCollection */ ); |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9382 break; |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9383 |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9384 case CMSCollector::Sweeping: |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9385 initialize(true /* fullGC */ , |
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
parents:
3293
diff
changeset
|
9386 cause /* cause of the GC */, |
1703
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9387 false /* recordGCBeginTime */, |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9388 false /* recordPreGCUsage */, |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9389 true /* recordPeakUsage */, |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9390 true /* recordPostGCusage */, |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9391 false /* recordAccumulatedGCTime */, |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9392 true /* recordGCEndTime */, |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9393 true /* countCollection */ ); |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9394 break; |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9395 |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9396 default: |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9397 ShouldNotReachHere(); |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9398 } |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9399 } |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9400 |