Mercurial > hg > truffle
annotate src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp @ 10265:92ef81e2f571
8003557: NPG: Klass* const k should be const Klass* k.
Summary: With NPG, const KlassOop klass which is in fact a definition converted to Klass* const, which is not the original intention. The right usage is converting them to const Klass*.
Reviewed-by: coleenp, kvn
Contributed-by: yumin.qi@oracle.com
author | minqi |
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date | Fri, 10 May 2013 08:27:30 -0700 |
parents | 2f50bc369470 |
children | a9d568b7df60 |
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" | |
40 #include "gc_implementation/shared/isGCActiveMark.hpp" | |
41 #include "gc_interface/collectedHeap.inline.hpp" | |
42 #include "memory/cardTableRS.hpp" | |
43 #include "memory/collectorPolicy.hpp" | |
44 #include "memory/gcLocker.inline.hpp" | |
45 #include "memory/genCollectedHeap.hpp" | |
46 #include "memory/genMarkSweep.hpp" | |
47 #include "memory/genOopClosures.inline.hpp" | |
48 #include "memory/iterator.hpp" | |
49 #include "memory/referencePolicy.hpp" | |
50 #include "memory/resourceArea.hpp" | |
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51 #include "memory/tenuredGeneration.hpp" |
1972 | 52 #include "oops/oop.inline.hpp" |
53 #include "prims/jvmtiExport.hpp" | |
54 #include "runtime/globals_extension.hpp" | |
55 #include "runtime/handles.inline.hpp" | |
56 #include "runtime/java.hpp" | |
57 #include "runtime/vmThread.hpp" | |
58 #include "services/memoryService.hpp" | |
59 #include "services/runtimeService.hpp" | |
0 | 60 |
61 // statics | |
62 CMSCollector* ConcurrentMarkSweepGeneration::_collector = NULL; | |
63 bool CMSCollector::_full_gc_requested = false; | |
64 | |
65 ////////////////////////////////////////////////////////////////// | |
66 // In support of CMS/VM thread synchronization | |
67 ////////////////////////////////////////////////////////////////// | |
68 // We split use of the CGC_lock into 2 "levels". | |
69 // The low-level locking is of the usual CGC_lock monitor. We introduce | |
70 // a higher level "token" (hereafter "CMS token") built on top of the | |
71 // low level monitor (hereafter "CGC lock"). | |
72 // The token-passing protocol gives priority to the VM thread. The | |
73 // CMS-lock doesn't provide any fairness guarantees, but clients | |
74 // should ensure that it is only held for very short, bounded | |
75 // durations. | |
76 // | |
77 // When either of the CMS thread or the VM thread is involved in | |
78 // collection operations during which it does not want the other | |
79 // thread to interfere, it obtains the CMS token. | |
80 // | |
81 // If either thread tries to get the token while the other has | |
82 // it, that thread waits. However, if the VM thread and CMS thread | |
83 // both want the token, then the VM thread gets priority while the | |
84 // CMS thread waits. This ensures, for instance, that the "concurrent" | |
85 // phases of the CMS thread's work do not block out the VM thread | |
86 // for long periods of time as the CMS thread continues to hog | |
87 // the token. (See bug 4616232). | |
88 // | |
89 // The baton-passing functions are, however, controlled by the | |
90 // flags _foregroundGCShouldWait and _foregroundGCIsActive, | |
91 // and here the low-level CMS lock, not the high level token, | |
92 // ensures mutual exclusion. | |
93 // | |
94 // Two important conditions that we have to satisfy: | |
95 // 1. if a thread does a low-level wait on the CMS lock, then it | |
96 // relinquishes the CMS token if it were holding that token | |
97 // when it acquired the low-level CMS lock. | |
98 // 2. any low-level notifications on the low-level lock | |
99 // should only be sent when a thread has relinquished the token. | |
100 // | |
101 // In the absence of either property, we'd have potential deadlock. | |
102 // | |
103 // We protect each of the CMS (concurrent and sequential) phases | |
104 // with the CMS _token_, not the CMS _lock_. | |
105 // | |
106 // The only code protected by CMS lock is the token acquisition code | |
107 // itself, see ConcurrentMarkSweepThread::[de]synchronize(), and the | |
108 // baton-passing code. | |
109 // | |
110 // Unfortunately, i couldn't come up with a good abstraction to factor and | |
111 // hide the naked CGC_lock manipulation in the baton-passing code | |
112 // further below. That's something we should try to do. Also, the proof | |
113 // of correctness of this 2-level locking scheme is far from obvious, | |
114 // and potentially quite slippery. We have an uneasy supsicion, for instance, | |
115 // that there may be a theoretical possibility of delay/starvation in the | |
116 // low-level lock/wait/notify scheme used for the baton-passing because of | |
117 // potential intereference with the priority scheme embodied in the | |
118 // CMS-token-passing protocol. See related comments at a CGC_lock->wait() | |
119 // invocation further below and marked with "XXX 20011219YSR". | |
120 // Indeed, as we note elsewhere, this may become yet more slippery | |
121 // in the presence of multiple CMS and/or multiple VM threads. XXX | |
122 | |
123 class CMSTokenSync: public StackObj { | |
124 private: | |
125 bool _is_cms_thread; | |
126 public: | |
127 CMSTokenSync(bool is_cms_thread): | |
128 _is_cms_thread(is_cms_thread) { | |
129 assert(is_cms_thread == Thread::current()->is_ConcurrentGC_thread(), | |
130 "Incorrect argument to constructor"); | |
131 ConcurrentMarkSweepThread::synchronize(_is_cms_thread); | |
132 } | |
133 | |
134 ~CMSTokenSync() { | |
135 assert(_is_cms_thread ? | |
136 ConcurrentMarkSweepThread::cms_thread_has_cms_token() : | |
137 ConcurrentMarkSweepThread::vm_thread_has_cms_token(), | |
138 "Incorrect state"); | |
139 ConcurrentMarkSweepThread::desynchronize(_is_cms_thread); | |
140 } | |
141 }; | |
142 | |
143 // Convenience class that does a CMSTokenSync, and then acquires | |
144 // upto three locks. | |
145 class CMSTokenSyncWithLocks: public CMSTokenSync { | |
146 private: | |
147 // Note: locks are acquired in textual declaration order | |
148 // and released in the opposite order | |
149 MutexLockerEx _locker1, _locker2, _locker3; | |
150 public: | |
151 CMSTokenSyncWithLocks(bool is_cms_thread, Mutex* mutex1, | |
152 Mutex* mutex2 = NULL, Mutex* mutex3 = NULL): | |
153 CMSTokenSync(is_cms_thread), | |
154 _locker1(mutex1, Mutex::_no_safepoint_check_flag), | |
155 _locker2(mutex2, Mutex::_no_safepoint_check_flag), | |
156 _locker3(mutex3, Mutex::_no_safepoint_check_flag) | |
157 { } | |
158 }; | |
159 | |
160 | |
161 // Wrapper class to temporarily disable icms during a foreground cms collection. | |
162 class ICMSDisabler: public StackObj { | |
163 public: | |
164 // The ctor disables icms and wakes up the thread so it notices the change; | |
165 // the dtor re-enables icms. Note that the CMSCollector methods will check | |
166 // CMSIncrementalMode. | |
167 ICMSDisabler() { CMSCollector::disable_icms(); CMSCollector::start_icms(); } | |
168 ~ICMSDisabler() { CMSCollector::enable_icms(); } | |
169 }; | |
170 | |
171 ////////////////////////////////////////////////////////////////// | |
172 // Concurrent Mark-Sweep Generation ///////////////////////////// | |
173 ////////////////////////////////////////////////////////////////// | |
174 | |
175 NOT_PRODUCT(CompactibleFreeListSpace* debug_cms_space;) | |
176 | |
177 // This struct contains per-thread things necessary to support parallel | |
178 // young-gen collection. | |
6197 | 179 class CMSParGCThreadState: public CHeapObj<mtGC> { |
0 | 180 public: |
181 CFLS_LAB lab; | |
182 PromotionInfo promo; | |
183 | |
184 // Constructor. | |
185 CMSParGCThreadState(CompactibleFreeListSpace* cfls) : lab(cfls) { | |
186 promo.setSpace(cfls); | |
187 } | |
188 }; | |
189 | |
190 ConcurrentMarkSweepGeneration::ConcurrentMarkSweepGeneration( | |
191 ReservedSpace rs, size_t initial_byte_size, int level, | |
192 CardTableRS* ct, bool use_adaptive_freelists, | |
6026 | 193 FreeBlockDictionary<FreeChunk>::DictionaryChoice dictionaryChoice) : |
0 | 194 CardGeneration(rs, initial_byte_size, level, ct), |
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195 _dilatation_factor(((double)MinChunkSize)/((double)(CollectedHeap::min_fill_size()))), |
0 | 196 _debug_collection_type(Concurrent_collection_type) |
197 { | |
198 HeapWord* bottom = (HeapWord*) _virtual_space.low(); | |
199 HeapWord* end = (HeapWord*) _virtual_space.high(); | |
200 | |
201 _direct_allocated_words = 0; | |
202 NOT_PRODUCT( | |
203 _numObjectsPromoted = 0; | |
204 _numWordsPromoted = 0; | |
205 _numObjectsAllocated = 0; | |
206 _numWordsAllocated = 0; | |
207 ) | |
208 | |
209 _cmsSpace = new CompactibleFreeListSpace(_bts, MemRegion(bottom, end), | |
210 use_adaptive_freelists, | |
211 dictionaryChoice); | |
212 NOT_PRODUCT(debug_cms_space = _cmsSpace;) | |
213 if (_cmsSpace == NULL) { | |
214 vm_exit_during_initialization( | |
215 "CompactibleFreeListSpace allocation failure"); | |
216 } | |
217 _cmsSpace->_gen = this; | |
218 | |
219 _gc_stats = new CMSGCStats(); | |
220 | |
221 // Verify the assumption that FreeChunk::_prev and OopDesc::_klass | |
222 // offsets match. The ability to tell free chunks from objects | |
223 // depends on this property. | |
224 debug_only( | |
225 FreeChunk* junk = NULL; | |
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226 assert(UseCompressedKlassPointers || |
187 | 227 junk->prev_addr() == (void*)(oop(junk)->klass_addr()), |
0 | 228 "Offset of FreeChunk::_prev within FreeChunk must match" |
229 " that of OopDesc::_klass within OopDesc"); | |
230 ) | |
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231 if (CollectedHeap::use_parallel_gc_threads()) { |
0 | 232 typedef CMSParGCThreadState* CMSParGCThreadStatePtr; |
233 _par_gc_thread_states = | |
6197 | 234 NEW_C_HEAP_ARRAY(CMSParGCThreadStatePtr, ParallelGCThreads, mtGC); |
0 | 235 if (_par_gc_thread_states == NULL) { |
236 vm_exit_during_initialization("Could not allocate par gc structs"); | |
237 } | |
238 for (uint i = 0; i < ParallelGCThreads; i++) { | |
239 _par_gc_thread_states[i] = new CMSParGCThreadState(cmsSpace()); | |
240 if (_par_gc_thread_states[i] == NULL) { | |
241 vm_exit_during_initialization("Could not allocate par gc structs"); | |
242 } | |
243 } | |
244 } else { | |
245 _par_gc_thread_states = NULL; | |
246 } | |
247 _incremental_collection_failed = false; | |
248 // The "dilatation_factor" is the expansion that can occur on | |
249 // account of the fact that the minimum object size in the CMS | |
250 // generation may be larger than that in, say, a contiguous young | |
251 // generation. | |
252 // Ideally, in the calculation below, we'd compute the dilatation | |
253 // factor as: MinChunkSize/(promoting_gen's min object size) | |
254 // Since we do not have such a general query interface for the | |
255 // promoting generation, we'll instead just use the mimimum | |
256 // object size (which today is a header's worth of space); | |
257 // note that all arithmetic is in units of HeapWords. | |
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258 assert(MinChunkSize >= CollectedHeap::min_fill_size(), "just checking"); |
0 | 259 assert(_dilatation_factor >= 1.0, "from previous assert"); |
260 } | |
261 | |
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262 |
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263 // The field "_initiating_occupancy" represents the occupancy percentage |
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264 // at which we trigger a new collection cycle. Unless explicitly specified |
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265 // via CMSInitiatingOccupancyFraction (argument "io" below), it |
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266 // is calculated by: |
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267 // |
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268 // Let "f" be MinHeapFreeRatio in |
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269 // |
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270 // _intiating_occupancy = 100-f + |
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271 // f * (CMSTriggerRatio/100) |
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272 // where CMSTriggerRatio is the argument "tr" below. |
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273 // |
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274 // That is, if we assume the heap is at its desired maximum occupancy at the |
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275 // end of a collection, we let CMSTriggerRatio of the (purported) free |
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276 // space be allocated before initiating a new collection cycle. |
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277 // |
8035 | 278 void ConcurrentMarkSweepGeneration::init_initiating_occupancy(intx io, uintx tr) { |
279 assert(io <= 100 && tr <= 100, "Check the arguments"); | |
94
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280 if (io >= 0) { |
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281 _initiating_occupancy = (double)io / 100.0; |
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282 } else { |
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283 _initiating_occupancy = ((100 - MinHeapFreeRatio) + |
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284 (double)(tr * MinHeapFreeRatio) / 100.0) |
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285 / 100.0; |
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286 } |
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287 } |
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288 |
0 | 289 void ConcurrentMarkSweepGeneration::ref_processor_init() { |
290 assert(collector() != NULL, "no collector"); | |
291 collector()->ref_processor_init(); | |
292 } | |
293 | |
294 void CMSCollector::ref_processor_init() { | |
295 if (_ref_processor == NULL) { | |
296 // Allocate and initialize a reference processor | |
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297 _ref_processor = |
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298 new ReferenceProcessor(_span, // span |
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299 (ParallelGCThreads > 1) && ParallelRefProcEnabled, // mt processing |
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300 (int) ParallelGCThreads, // mt processing degree |
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301 _cmsGen->refs_discovery_is_mt(), // mt discovery |
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302 (int) MAX2(ConcGCThreads, ParallelGCThreads), // mt discovery degree |
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303 _cmsGen->refs_discovery_is_atomic(), // discovery is not atomic |
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304 &_is_alive_closure, // closure for liveness info |
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305 false); // next field updates do not need write barrier |
0 | 306 // Initialize the _ref_processor field of CMSGen |
307 _cmsGen->set_ref_processor(_ref_processor); | |
308 | |
309 } | |
310 } | |
311 | |
312 CMSAdaptiveSizePolicy* CMSCollector::size_policy() { | |
313 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
314 assert(gch->kind() == CollectedHeap::GenCollectedHeap, | |
315 "Wrong type of heap"); | |
316 CMSAdaptiveSizePolicy* sp = (CMSAdaptiveSizePolicy*) | |
317 gch->gen_policy()->size_policy(); | |
318 assert(sp->is_gc_cms_adaptive_size_policy(), | |
319 "Wrong type of size policy"); | |
320 return sp; | |
321 } | |
322 | |
323 CMSGCAdaptivePolicyCounters* CMSCollector::gc_adaptive_policy_counters() { | |
324 CMSGCAdaptivePolicyCounters* results = | |
325 (CMSGCAdaptivePolicyCounters*) collector_policy()->counters(); | |
326 assert( | |
327 results->kind() == GCPolicyCounters::CMSGCAdaptivePolicyCountersKind, | |
328 "Wrong gc policy counter kind"); | |
329 return results; | |
330 } | |
331 | |
332 | |
333 void ConcurrentMarkSweepGeneration::initialize_performance_counters() { | |
334 | |
335 const char* gen_name = "old"; | |
336 | |
337 // Generation Counters - generation 1, 1 subspace | |
338 _gen_counters = new GenerationCounters(gen_name, 1, 1, &_virtual_space); | |
339 | |
340 _space_counters = new GSpaceCounters(gen_name, 0, | |
341 _virtual_space.reserved_size(), | |
342 this, _gen_counters); | |
343 } | |
344 | |
345 CMSStats::CMSStats(ConcurrentMarkSweepGeneration* cms_gen, unsigned int alpha): | |
346 _cms_gen(cms_gen) | |
347 { | |
348 assert(alpha <= 100, "bad value"); | |
349 _saved_alpha = alpha; | |
350 | |
351 // Initialize the alphas to the bootstrap value of 100. | |
352 _gc0_alpha = _cms_alpha = 100; | |
353 | |
354 _cms_begin_time.update(); | |
355 _cms_end_time.update(); | |
356 | |
357 _gc0_duration = 0.0; | |
358 _gc0_period = 0.0; | |
359 _gc0_promoted = 0; | |
360 | |
361 _cms_duration = 0.0; | |
362 _cms_period = 0.0; | |
363 _cms_allocated = 0; | |
364 | |
365 _cms_used_at_gc0_begin = 0; | |
366 _cms_used_at_gc0_end = 0; | |
367 _allow_duty_cycle_reduction = false; | |
368 _valid_bits = 0; | |
369 _icms_duty_cycle = CMSIncrementalDutyCycle; | |
370 } | |
371 | |
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372 double CMSStats::cms_free_adjustment_factor(size_t free) const { |
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373 // TBD: CR 6909490 |
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374 return 1.0; |
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375 } |
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376 |
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377 void CMSStats::adjust_cms_free_adjustment_factor(bool fail, size_t free) { |
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378 } |
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379 |
0 | 380 // If promotion failure handling is on use |
381 // the padded average size of the promotion for each | |
382 // young generation collection. | |
383 double CMSStats::time_until_cms_gen_full() const { | |
384 size_t cms_free = _cms_gen->cmsSpace()->free(); | |
385 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
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386 size_t expected_promotion = MIN2(gch->get_gen(0)->capacity(), |
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387 (size_t) _cms_gen->gc_stats()->avg_promoted()->padded_average()); |
0 | 388 if (cms_free > expected_promotion) { |
389 // Start a cms collection if there isn't enough space to promote | |
390 // for the next minor collection. Use the padded average as | |
391 // a safety factor. | |
392 cms_free -= expected_promotion; | |
393 | |
394 // Adjust by the safety factor. | |
395 double cms_free_dbl = (double)cms_free; | |
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396 double cms_adjustment = (100.0 - CMSIncrementalSafetyFactor)/100.0; |
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397 // Apply a further correction factor which tries to adjust |
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398 // for recent occurance of concurrent mode failures. |
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399 cms_adjustment = cms_adjustment * cms_free_adjustment_factor(cms_free); |
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400 cms_free_dbl = cms_free_dbl * cms_adjustment; |
0 | 401 |
402 if (PrintGCDetails && Verbose) { | |
403 gclog_or_tty->print_cr("CMSStats::time_until_cms_gen_full: cms_free " | |
404 SIZE_FORMAT " expected_promotion " SIZE_FORMAT, | |
405 cms_free, expected_promotion); | |
406 gclog_or_tty->print_cr(" cms_free_dbl %f cms_consumption_rate %f", | |
407 cms_free_dbl, cms_consumption_rate() + 1.0); | |
408 } | |
409 // Add 1 in case the consumption rate goes to zero. | |
410 return cms_free_dbl / (cms_consumption_rate() + 1.0); | |
411 } | |
412 return 0.0; | |
413 } | |
414 | |
415 // Compare the duration of the cms collection to the | |
416 // time remaining before the cms generation is empty. | |
417 // Note that the time from the start of the cms collection | |
418 // to the start of the cms sweep (less than the total | |
419 // duration of the cms collection) can be used. This | |
420 // has been tried and some applications experienced | |
421 // promotion failures early in execution. This was | |
422 // possibly because the averages were not accurate | |
423 // enough at the beginning. | |
424 double CMSStats::time_until_cms_start() const { | |
425 // We add "gc0_period" to the "work" calculation | |
426 // below because this query is done (mostly) at the | |
427 // end of a scavenge, so we need to conservatively | |
428 // account for that much possible delay | |
429 // in the query so as to avoid concurrent mode failures | |
430 // due to starting the collection just a wee bit too | |
431 // late. | |
432 double work = cms_duration() + gc0_period(); | |
433 double deadline = time_until_cms_gen_full(); | |
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434 // If a concurrent mode failure occurred recently, we want to be |
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435 // more conservative and halve our expected time_until_cms_gen_full() |
0 | 436 if (work > deadline) { |
437 if (Verbose && PrintGCDetails) { | |
438 gclog_or_tty->print( | |
439 " CMSCollector: collect because of anticipated promotion " | |
440 "before full %3.7f + %3.7f > %3.7f ", cms_duration(), | |
441 gc0_period(), time_until_cms_gen_full()); | |
442 } | |
443 return 0.0; | |
444 } | |
445 return work - deadline; | |
446 } | |
447 | |
448 // Return a duty cycle based on old_duty_cycle and new_duty_cycle, limiting the | |
449 // amount of change to prevent wild oscillation. | |
450 unsigned int CMSStats::icms_damped_duty_cycle(unsigned int old_duty_cycle, | |
451 unsigned int new_duty_cycle) { | |
452 assert(old_duty_cycle <= 100, "bad input value"); | |
453 assert(new_duty_cycle <= 100, "bad input value"); | |
454 | |
455 // Note: use subtraction with caution since it may underflow (values are | |
456 // unsigned). Addition is safe since we're in the range 0-100. | |
457 unsigned int damped_duty_cycle = new_duty_cycle; | |
458 if (new_duty_cycle < old_duty_cycle) { | |
459 const unsigned int largest_delta = MAX2(old_duty_cycle / 4, 5U); | |
460 if (new_duty_cycle + largest_delta < old_duty_cycle) { | |
461 damped_duty_cycle = old_duty_cycle - largest_delta; | |
462 } | |
463 } else if (new_duty_cycle > old_duty_cycle) { | |
464 const unsigned int largest_delta = MAX2(old_duty_cycle / 4, 15U); | |
465 if (new_duty_cycle > old_duty_cycle + largest_delta) { | |
466 damped_duty_cycle = MIN2(old_duty_cycle + largest_delta, 100U); | |
467 } | |
468 } | |
469 assert(damped_duty_cycle <= 100, "invalid duty cycle computed"); | |
470 | |
471 if (CMSTraceIncrementalPacing) { | |
472 gclog_or_tty->print(" [icms_damped_duty_cycle(%d,%d) = %d] ", | |
473 old_duty_cycle, new_duty_cycle, damped_duty_cycle); | |
474 } | |
475 return damped_duty_cycle; | |
476 } | |
477 | |
478 unsigned int CMSStats::icms_update_duty_cycle_impl() { | |
479 assert(CMSIncrementalPacing && valid(), | |
480 "should be handled in icms_update_duty_cycle()"); | |
481 | |
482 double cms_time_so_far = cms_timer().seconds(); | |
483 double scaled_duration = cms_duration_per_mb() * _cms_used_at_gc0_end / M; | |
484 double scaled_duration_remaining = fabsd(scaled_duration - cms_time_so_far); | |
485 | |
486 // Avoid division by 0. | |
487 double time_until_full = MAX2(time_until_cms_gen_full(), 0.01); | |
488 double duty_cycle_dbl = 100.0 * scaled_duration_remaining / time_until_full; | |
489 | |
490 unsigned int new_duty_cycle = MIN2((unsigned int)duty_cycle_dbl, 100U); | |
491 if (new_duty_cycle > _icms_duty_cycle) { | |
492 // Avoid very small duty cycles (1 or 2); 0 is allowed. | |
493 if (new_duty_cycle > 2) { | |
494 _icms_duty_cycle = icms_damped_duty_cycle(_icms_duty_cycle, | |
495 new_duty_cycle); | |
496 } | |
497 } else if (_allow_duty_cycle_reduction) { | |
498 // The duty cycle is reduced only once per cms cycle (see record_cms_end()). | |
499 new_duty_cycle = icms_damped_duty_cycle(_icms_duty_cycle, new_duty_cycle); | |
500 // Respect the minimum duty cycle. | |
501 unsigned int min_duty_cycle = (unsigned int)CMSIncrementalDutyCycleMin; | |
502 _icms_duty_cycle = MAX2(new_duty_cycle, min_duty_cycle); | |
503 } | |
504 | |
505 if (PrintGCDetails || CMSTraceIncrementalPacing) { | |
506 gclog_or_tty->print(" icms_dc=%d ", _icms_duty_cycle); | |
507 } | |
508 | |
509 _allow_duty_cycle_reduction = false; | |
510 return _icms_duty_cycle; | |
511 } | |
512 | |
513 #ifndef PRODUCT | |
514 void CMSStats::print_on(outputStream *st) const { | |
515 st->print(" gc0_alpha=%d,cms_alpha=%d", _gc0_alpha, _cms_alpha); | |
516 st->print(",gc0_dur=%g,gc0_per=%g,gc0_promo=" SIZE_FORMAT, | |
517 gc0_duration(), gc0_period(), gc0_promoted()); | |
518 st->print(",cms_dur=%g,cms_dur_per_mb=%g,cms_per=%g,cms_alloc=" SIZE_FORMAT, | |
519 cms_duration(), cms_duration_per_mb(), | |
520 cms_period(), cms_allocated()); | |
521 st->print(",cms_since_beg=%g,cms_since_end=%g", | |
522 cms_time_since_begin(), cms_time_since_end()); | |
523 st->print(",cms_used_beg=" SIZE_FORMAT ",cms_used_end=" SIZE_FORMAT, | |
524 _cms_used_at_gc0_begin, _cms_used_at_gc0_end); | |
525 if (CMSIncrementalMode) { | |
526 st->print(",dc=%d", icms_duty_cycle()); | |
527 } | |
528 | |
529 if (valid()) { | |
530 st->print(",promo_rate=%g,cms_alloc_rate=%g", | |
531 promotion_rate(), cms_allocation_rate()); | |
532 st->print(",cms_consumption_rate=%g,time_until_full=%g", | |
533 cms_consumption_rate(), time_until_cms_gen_full()); | |
534 } | |
535 st->print(" "); | |
536 } | |
537 #endif // #ifndef PRODUCT | |
538 | |
539 CMSCollector::CollectorState CMSCollector::_collectorState = | |
540 CMSCollector::Idling; | |
541 bool CMSCollector::_foregroundGCIsActive = false; | |
542 bool CMSCollector::_foregroundGCShouldWait = false; | |
543 | |
544 CMSCollector::CMSCollector(ConcurrentMarkSweepGeneration* cmsGen, | |
545 CardTableRS* ct, | |
546 ConcurrentMarkSweepPolicy* cp): | |
547 _cmsGen(cmsGen), | |
548 _ct(ct), | |
549 _ref_processor(NULL), // will be set later | |
550 _conc_workers(NULL), // may be set later | |
551 _abort_preclean(false), | |
552 _start_sampling(false), | |
553 _between_prologue_and_epilogue(false), | |
554 _markBitMap(0, Mutex::leaf + 1, "CMS_markBitMap_lock"), | |
555 _modUnionTable((CardTableModRefBS::card_shift - LogHeapWordSize), | |
556 -1 /* lock-free */, "No_lock" /* dummy */), | |
557 _modUnionClosure(&_modUnionTable), | |
558 _modUnionClosurePar(&_modUnionTable), | |
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559 // Adjust my span to cover old (cms) gen |
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560 _span(cmsGen->reserved()), |
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561 // Construct the is_alive_closure with _span & markBitMap |
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562 _is_alive_closure(_span, &_markBitMap), |
0 | 563 _restart_addr(NULL), |
564 _overflow_list(NULL), | |
565 _stats(cmsGen), | |
566 _eden_chunk_array(NULL), // may be set in ctor body | |
567 _eden_chunk_capacity(0), // -- ditto -- | |
568 _eden_chunk_index(0), // -- ditto -- | |
569 _survivor_plab_array(NULL), // -- ditto -- | |
570 _survivor_chunk_array(NULL), // -- ditto -- | |
571 _survivor_chunk_capacity(0), // -- ditto -- | |
572 _survivor_chunk_index(0), // -- ditto -- | |
573 _ser_pmc_preclean_ovflw(0), | |
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574 _ser_kac_preclean_ovflw(0), |
0 | 575 _ser_pmc_remark_ovflw(0), |
576 _par_pmc_remark_ovflw(0), | |
577 _ser_kac_ovflw(0), | |
578 _par_kac_ovflw(0), | |
579 #ifndef PRODUCT | |
580 _num_par_pushes(0), | |
581 #endif | |
582 _collection_count_start(0), | |
583 _verifying(false), | |
584 _icms_start_limit(NULL), | |
585 _icms_stop_limit(NULL), | |
586 _verification_mark_bm(0, Mutex::leaf + 1, "CMS_verification_mark_bm_lock"), | |
587 _completed_initialization(false), | |
588 _collector_policy(cp), | |
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589 _should_unload_classes(false), |
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590 _concurrent_cycles_since_last_unload(0), |
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591 _roots_scanning_options(0), |
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592 _inter_sweep_estimate(CMS_SweepWeight, CMS_SweepPadding), |
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593 _intra_sweep_estimate(CMS_SweepWeight, CMS_SweepPadding) |
0 | 594 { |
595 if (ExplicitGCInvokesConcurrentAndUnloadsClasses) { | |
596 ExplicitGCInvokesConcurrent = true; | |
597 } | |
598 // Now expand the span and allocate the collection support structures | |
599 // (MUT, marking bit map etc.) to cover both generations subject to | |
600 // collection. | |
601 | |
602 // For use by dirty card to oop closures. | |
603 _cmsGen->cmsSpace()->set_collector(this); | |
604 | |
605 // Allocate MUT and marking bit map | |
606 { | |
607 MutexLockerEx x(_markBitMap.lock(), Mutex::_no_safepoint_check_flag); | |
608 if (!_markBitMap.allocate(_span)) { | |
609 warning("Failed to allocate CMS Bit Map"); | |
610 return; | |
611 } | |
612 assert(_markBitMap.covers(_span), "_markBitMap inconsistency?"); | |
613 } | |
614 { | |
615 _modUnionTable.allocate(_span); | |
616 assert(_modUnionTable.covers(_span), "_modUnionTable inconsistency?"); | |
617 } | |
618 | |
1284 | 619 if (!_markStack.allocate(MarkStackSize)) { |
0 | 620 warning("Failed to allocate CMS Marking Stack"); |
621 return; | |
622 } | |
623 | |
624 // Support for multi-threaded concurrent phases | |
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625 if (CMSConcurrentMTEnabled) { |
1284 | 626 if (FLAG_IS_DEFAULT(ConcGCThreads)) { |
0 | 627 // just for now |
1284 | 628 FLAG_SET_DEFAULT(ConcGCThreads, (ParallelGCThreads + 3)/4); |
629 } | |
630 if (ConcGCThreads > 1) { | |
0 | 631 _conc_workers = new YieldingFlexibleWorkGang("Parallel CMS Threads", |
1284 | 632 ConcGCThreads, true); |
0 | 633 if (_conc_workers == NULL) { |
634 warning("GC/CMS: _conc_workers allocation failure: " | |
635 "forcing -CMSConcurrentMTEnabled"); | |
636 CMSConcurrentMTEnabled = false; | |
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637 } else { |
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638 _conc_workers->initialize_workers(); |
0 | 639 } |
640 } else { | |
641 CMSConcurrentMTEnabled = false; | |
642 } | |
643 } | |
644 if (!CMSConcurrentMTEnabled) { | |
1284 | 645 ConcGCThreads = 0; |
0 | 646 } else { |
647 // Turn off CMSCleanOnEnter optimization temporarily for | |
648 // the MT case where it's not fixed yet; see 6178663. | |
649 CMSCleanOnEnter = false; | |
650 } | |
1284 | 651 assert((_conc_workers != NULL) == (ConcGCThreads > 1), |
0 | 652 "Inconsistency"); |
653 | |
654 // Parallel task queues; these are shared for the | |
655 // concurrent and stop-world phases of CMS, but | |
656 // are not shared with parallel scavenge (ParNew). | |
657 { | |
658 uint i; | |
1284 | 659 uint num_queues = (uint) MAX2(ParallelGCThreads, ConcGCThreads); |
0 | 660 |
661 if ((CMSParallelRemarkEnabled || CMSConcurrentMTEnabled | |
662 || ParallelRefProcEnabled) | |
663 && num_queues > 0) { | |
664 _task_queues = new OopTaskQueueSet(num_queues); | |
665 if (_task_queues == NULL) { | |
666 warning("task_queues allocation failure."); | |
667 return; | |
668 } | |
6197 | 669 _hash_seed = NEW_C_HEAP_ARRAY(int, num_queues, mtGC); |
0 | 670 if (_hash_seed == NULL) { |
671 warning("_hash_seed array allocation failure"); | |
672 return; | |
673 } | |
674 | |
1665 | 675 typedef Padded<OopTaskQueue> PaddedOopTaskQueue; |
0 | 676 for (i = 0; i < num_queues; i++) { |
1665 | 677 PaddedOopTaskQueue *q = new PaddedOopTaskQueue(); |
678 if (q == NULL) { | |
0 | 679 warning("work_queue allocation failure."); |
680 return; | |
681 } | |
1665 | 682 _task_queues->register_queue(i, q); |
0 | 683 } |
684 for (i = 0; i < num_queues; i++) { | |
685 _task_queues->queue(i)->initialize(); | |
686 _hash_seed[i] = 17; // copied from ParNew | |
687 } | |
688 } | |
689 } | |
690 | |
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691 _cmsGen ->init_initiating_occupancy(CMSInitiatingOccupancyFraction, CMSTriggerRatio); |
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692 |
0 | 693 // Clip CMSBootstrapOccupancy between 0 and 100. |
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694 _bootstrap_occupancy = ((double)MIN2((uintx)100, MAX2((uintx)0, CMSBootstrapOccupancy))) |
0 | 695 /(double)100; |
696 | |
697 _full_gcs_since_conc_gc = 0; | |
698 | |
699 // Now tell CMS generations the identity of their collector | |
700 ConcurrentMarkSweepGeneration::set_collector(this); | |
701 | |
702 // Create & start a CMS thread for this CMS collector | |
703 _cmsThread = ConcurrentMarkSweepThread::start(this); | |
704 assert(cmsThread() != NULL, "CMS Thread should have been created"); | |
705 assert(cmsThread()->collector() == this, | |
706 "CMS Thread should refer to this gen"); | |
707 assert(CGC_lock != NULL, "Where's the CGC_lock?"); | |
708 | |
709 // Support for parallelizing young gen rescan | |
710 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
711 _young_gen = gch->prev_gen(_cmsGen); | |
712 if (gch->supports_inline_contig_alloc()) { | |
713 _top_addr = gch->top_addr(); | |
714 _end_addr = gch->end_addr(); | |
715 assert(_young_gen != NULL, "no _young_gen"); | |
716 _eden_chunk_index = 0; | |
717 _eden_chunk_capacity = (_young_gen->max_capacity()+CMSSamplingGrain)/CMSSamplingGrain; | |
6197 | 718 _eden_chunk_array = NEW_C_HEAP_ARRAY(HeapWord*, _eden_chunk_capacity, mtGC); |
0 | 719 if (_eden_chunk_array == NULL) { |
720 _eden_chunk_capacity = 0; | |
721 warning("GC/CMS: _eden_chunk_array allocation failure"); | |
722 } | |
723 } | |
724 assert(_eden_chunk_array != NULL || _eden_chunk_capacity == 0, "Error"); | |
725 | |
726 // Support for parallelizing survivor space rescan | |
727 if (CMSParallelRemarkEnabled && CMSParallelSurvivorRemarkEnabled) { | |
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728 const size_t max_plab_samples = |
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729 ((DefNewGeneration*)_young_gen)->max_survivor_size()/MinTLABSize; |
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730 |
6197 | 731 _survivor_plab_array = NEW_C_HEAP_ARRAY(ChunkArray, ParallelGCThreads, mtGC); |
732 _survivor_chunk_array = NEW_C_HEAP_ARRAY(HeapWord*, 2*max_plab_samples, mtGC); | |
733 _cursor = NEW_C_HEAP_ARRAY(size_t, ParallelGCThreads, mtGC); | |
0 | 734 if (_survivor_plab_array == NULL || _survivor_chunk_array == NULL |
735 || _cursor == NULL) { | |
736 warning("Failed to allocate survivor plab/chunk array"); | |
737 if (_survivor_plab_array != NULL) { | |
6197 | 738 FREE_C_HEAP_ARRAY(ChunkArray, _survivor_plab_array, mtGC); |
0 | 739 _survivor_plab_array = NULL; |
740 } | |
741 if (_survivor_chunk_array != NULL) { | |
6197 | 742 FREE_C_HEAP_ARRAY(HeapWord*, _survivor_chunk_array, mtGC); |
0 | 743 _survivor_chunk_array = NULL; |
744 } | |
745 if (_cursor != NULL) { | |
6197 | 746 FREE_C_HEAP_ARRAY(size_t, _cursor, mtGC); |
0 | 747 _cursor = NULL; |
748 } | |
749 } else { | |
750 _survivor_chunk_capacity = 2*max_plab_samples; | |
751 for (uint i = 0; i < ParallelGCThreads; i++) { | |
6197 | 752 HeapWord** vec = NEW_C_HEAP_ARRAY(HeapWord*, max_plab_samples, mtGC); |
0 | 753 if (vec == NULL) { |
754 warning("Failed to allocate survivor plab array"); | |
755 for (int j = i; j > 0; j--) { | |
6197 | 756 FREE_C_HEAP_ARRAY(HeapWord*, _survivor_plab_array[j-1].array(), mtGC); |
0 | 757 } |
6197 | 758 FREE_C_HEAP_ARRAY(ChunkArray, _survivor_plab_array, mtGC); |
759 FREE_C_HEAP_ARRAY(HeapWord*, _survivor_chunk_array, mtGC); | |
0 | 760 _survivor_plab_array = NULL; |
761 _survivor_chunk_array = NULL; | |
762 _survivor_chunk_capacity = 0; | |
763 break; | |
764 } else { | |
765 ChunkArray* cur = | |
766 ::new (&_survivor_plab_array[i]) ChunkArray(vec, | |
767 max_plab_samples); | |
768 assert(cur->end() == 0, "Should be 0"); | |
769 assert(cur->array() == vec, "Should be vec"); | |
770 assert(cur->capacity() == max_plab_samples, "Error"); | |
771 } | |
772 } | |
773 } | |
774 } | |
775 assert( ( _survivor_plab_array != NULL | |
776 && _survivor_chunk_array != NULL) | |
777 || ( _survivor_chunk_capacity == 0 | |
778 && _survivor_chunk_index == 0), | |
779 "Error"); | |
780 | |
781 // Choose what strong roots should be scanned depending on verification options | |
782 if (!CMSClassUnloadingEnabled) { | |
783 // If class unloading is disabled we want to include all classes into the root set. | |
784 add_root_scanning_option(SharedHeap::SO_AllClasses); | |
785 } else { | |
786 add_root_scanning_option(SharedHeap::SO_SystemClasses); | |
787 } | |
788 | |
789 NOT_PRODUCT(_overflow_counter = CMSMarkStackOverflowInterval;) | |
790 _gc_counters = new CollectorCounters("CMS", 1); | |
791 _completed_initialization = true; | |
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792 _inter_sweep_timer.start(); // start of time |
0 | 793 } |
794 | |
795 const char* ConcurrentMarkSweepGeneration::name() const { | |
796 return "concurrent mark-sweep generation"; | |
797 } | |
798 void ConcurrentMarkSweepGeneration::update_counters() { | |
799 if (UsePerfData) { | |
800 _space_counters->update_all(); | |
801 _gen_counters->update_all(); | |
802 } | |
803 } | |
804 | |
805 // this is an optimized version of update_counters(). it takes the | |
806 // used value as a parameter rather than computing it. | |
807 // | |
808 void ConcurrentMarkSweepGeneration::update_counters(size_t used) { | |
809 if (UsePerfData) { | |
810 _space_counters->update_used(used); | |
811 _space_counters->update_capacity(); | |
812 _gen_counters->update_all(); | |
813 } | |
814 } | |
815 | |
816 void ConcurrentMarkSweepGeneration::print() const { | |
817 Generation::print(); | |
818 cmsSpace()->print(); | |
819 } | |
820 | |
821 #ifndef PRODUCT | |
822 void ConcurrentMarkSweepGeneration::print_statistics() { | |
823 cmsSpace()->printFLCensus(0); | |
824 } | |
825 #endif | |
826 | |
827 void ConcurrentMarkSweepGeneration::printOccupancy(const char *s) { | |
828 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
829 if (PrintGCDetails) { | |
830 if (Verbose) { | |
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831 gclog_or_tty->print("[%d %s-%s: "SIZE_FORMAT"("SIZE_FORMAT")]", |
0 | 832 level(), short_name(), s, used(), capacity()); |
833 } else { | |
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834 gclog_or_tty->print("[%d %s-%s: "SIZE_FORMAT"K("SIZE_FORMAT"K)]", |
0 | 835 level(), short_name(), s, used() / K, capacity() / K); |
836 } | |
837 } | |
838 if (Verbose) { | |
839 gclog_or_tty->print(" "SIZE_FORMAT"("SIZE_FORMAT")", | |
840 gch->used(), gch->capacity()); | |
841 } else { | |
842 gclog_or_tty->print(" "SIZE_FORMAT"K("SIZE_FORMAT"K)", | |
843 gch->used() / K, gch->capacity() / K); | |
844 } | |
845 } | |
846 | |
847 size_t | |
848 ConcurrentMarkSweepGeneration::contiguous_available() const { | |
849 // dld proposes an improvement in precision here. If the committed | |
850 // part of the space ends in a free block we should add that to | |
851 // uncommitted size in the calculation below. Will make this | |
852 // change later, staying with the approximation below for the | |
853 // time being. -- ysr. | |
854 return MAX2(_virtual_space.uncommitted_size(), unsafe_max_alloc_nogc()); | |
855 } | |
856 | |
857 size_t | |
858 ConcurrentMarkSweepGeneration::unsafe_max_alloc_nogc() const { | |
859 return _cmsSpace->max_alloc_in_words() * HeapWordSize; | |
860 } | |
861 | |
862 size_t ConcurrentMarkSweepGeneration::max_available() const { | |
863 return free() + _virtual_space.uncommitted_size(); | |
864 } | |
865 | |
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866 bool ConcurrentMarkSweepGeneration::promotion_attempt_is_safe(size_t max_promotion_in_bytes) const { |
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867 size_t available = max_available(); |
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868 size_t av_promo = (size_t)gc_stats()->avg_promoted()->padded_average(); |
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869 bool res = (available >= av_promo) || (available >= max_promotion_in_bytes); |
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870 if (Verbose && PrintGCDetails) { |
1888
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871 gclog_or_tty->print_cr( |
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872 "CMS: promo attempt is%s safe: available("SIZE_FORMAT") %s av_promo("SIZE_FORMAT")," |
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873 "max_promo("SIZE_FORMAT")", |
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874 res? "":" not", available, res? ">=":"<", |
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875 av_promo, max_promotion_in_bytes); |
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876 } |
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877 return res; |
0 | 878 } |
879 | |
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880 // At a promotion failure dump information on block layout in heap |
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881 // (cms old generation). |
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882 void ConcurrentMarkSweepGeneration::promotion_failure_occurred() { |
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883 if (CMSDumpAtPromotionFailure) { |
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884 cmsSpace()->dump_at_safepoint_with_locks(collector(), gclog_or_tty); |
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885 } |
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886 } |
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887 |
0 | 888 CompactibleSpace* |
889 ConcurrentMarkSweepGeneration::first_compaction_space() const { | |
890 return _cmsSpace; | |
891 } | |
892 | |
893 void ConcurrentMarkSweepGeneration::reset_after_compaction() { | |
894 // Clear the promotion information. These pointers can be adjusted | |
895 // along with all the other pointers into the heap but | |
896 // compaction is expected to be a rare event with | |
897 // a heap using cms so don't do it without seeing the need. | |
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898 if (CollectedHeap::use_parallel_gc_threads()) { |
0 | 899 for (uint i = 0; i < ParallelGCThreads; i++) { |
900 _par_gc_thread_states[i]->promo.reset(); | |
901 } | |
902 } | |
903 } | |
904 | |
905 void ConcurrentMarkSweepGeneration::space_iterate(SpaceClosure* blk, bool usedOnly) { | |
906 blk->do_space(_cmsSpace); | |
907 } | |
908 | |
909 void ConcurrentMarkSweepGeneration::compute_new_size() { | |
910 assert_locked_or_safepoint(Heap_lock); | |
911 | |
912 // If incremental collection failed, we just want to expand | |
913 // to the limit. | |
914 if (incremental_collection_failed()) { | |
915 clear_incremental_collection_failed(); | |
916 grow_to_reserved(); | |
917 return; | |
918 } | |
919 | |
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920 // Compute some numbers about the state of the heap. |
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921 const size_t used_after_gc = used(); |
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922 const size_t capacity_after_gc = capacity(); |
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923 |
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924 CardGeneration::compute_new_size(); |
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925 |
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926 // Reset again after a possible resizing |
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927 cmsSpace()->reset_after_compaction(); |
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928 |
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929 assert(used() == used_after_gc && used_after_gc <= capacity(), |
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930 err_msg("used: " SIZE_FORMAT " used_after_gc: " SIZE_FORMAT |
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931 " capacity: " SIZE_FORMAT, used(), used_after_gc, capacity())); |
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932 } |
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933 |
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934 void ConcurrentMarkSweepGeneration::compute_new_size_free_list() { |
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935 assert_locked_or_safepoint(Heap_lock); |
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936 |
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937 // If incremental collection failed, we just want to expand |
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938 // to the limit. |
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939 if (incremental_collection_failed()) { |
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940 clear_incremental_collection_failed(); |
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941 grow_to_reserved(); |
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942 return; |
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943 } |
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944 |
0 | 945 double free_percentage = ((double) free()) / capacity(); |
946 double desired_free_percentage = (double) MinHeapFreeRatio / 100; | |
947 double maximum_free_percentage = (double) MaxHeapFreeRatio / 100; | |
948 | |
949 // compute expansion delta needed for reaching desired free percentage | |
950 if (free_percentage < desired_free_percentage) { | |
951 size_t desired_capacity = (size_t)(used() / ((double) 1 - desired_free_percentage)); | |
952 assert(desired_capacity >= capacity(), "invalid expansion size"); | |
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953 size_t expand_bytes = MAX2(desired_capacity - capacity(), MinHeapDeltaBytes); |
0 | 954 if (PrintGCDetails && Verbose) { |
955 size_t desired_capacity = (size_t)(used() / ((double) 1 - desired_free_percentage)); | |
956 gclog_or_tty->print_cr("\nFrom compute_new_size: "); | |
957 gclog_or_tty->print_cr(" Free fraction %f", free_percentage); | |
958 gclog_or_tty->print_cr(" Desired free fraction %f", | |
959 desired_free_percentage); | |
960 gclog_or_tty->print_cr(" Maximum free fraction %f", | |
961 maximum_free_percentage); | |
962 gclog_or_tty->print_cr(" Capactiy "SIZE_FORMAT, capacity()/1000); | |
963 gclog_or_tty->print_cr(" Desired capacity "SIZE_FORMAT, | |
964 desired_capacity/1000); | |
965 int prev_level = level() - 1; | |
966 if (prev_level >= 0) { | |
967 size_t prev_size = 0; | |
968 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
969 Generation* prev_gen = gch->_gens[prev_level]; | |
970 prev_size = prev_gen->capacity(); | |
971 gclog_or_tty->print_cr(" Younger gen size "SIZE_FORMAT, | |
972 prev_size/1000); | |
973 } | |
974 gclog_or_tty->print_cr(" unsafe_max_alloc_nogc "SIZE_FORMAT, | |
975 unsafe_max_alloc_nogc()/1000); | |
976 gclog_or_tty->print_cr(" contiguous available "SIZE_FORMAT, | |
977 contiguous_available()/1000); | |
978 gclog_or_tty->print_cr(" Expand by "SIZE_FORMAT" (bytes)", | |
979 expand_bytes); | |
980 } | |
981 // safe if expansion fails | |
982 expand(expand_bytes, 0, CMSExpansionCause::_satisfy_free_ratio); | |
983 if (PrintGCDetails && Verbose) { | |
984 gclog_or_tty->print_cr(" Expanded free fraction %f", | |
985 ((double) free()) / capacity()); | |
986 } | |
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987 } else { |
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988 size_t desired_capacity = (size_t)(used() / ((double) 1 - desired_free_percentage)); |
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989 assert(desired_capacity <= capacity(), "invalid expansion size"); |
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990 size_t shrink_bytes = capacity() - desired_capacity; |
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991 // Don't shrink unless the delta is greater than the minimum shrink we want |
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992 if (shrink_bytes >= MinHeapDeltaBytes) { |
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993 shrink_free_list_by(shrink_bytes); |
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994 } |
0 | 995 } |
996 } | |
997 | |
998 Mutex* ConcurrentMarkSweepGeneration::freelistLock() const { | |
999 return cmsSpace()->freelistLock(); | |
1000 } | |
1001 | |
1002 HeapWord* ConcurrentMarkSweepGeneration::allocate(size_t size, | |
1003 bool tlab) { | |
1004 CMSSynchronousYieldRequest yr; | |
1005 MutexLockerEx x(freelistLock(), | |
1006 Mutex::_no_safepoint_check_flag); | |
1007 return have_lock_and_allocate(size, tlab); | |
1008 } | |
1009 | |
1010 HeapWord* ConcurrentMarkSweepGeneration::have_lock_and_allocate(size_t size, | |
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1011 bool tlab /* ignored */) { |
0 | 1012 assert_lock_strong(freelistLock()); |
1013 size_t adjustedSize = CompactibleFreeListSpace::adjustObjectSize(size); | |
1014 HeapWord* res = cmsSpace()->allocate(adjustedSize); | |
1015 // Allocate the object live (grey) if the background collector has | |
1016 // started marking. This is necessary because the marker may | |
1017 // have passed this address and consequently this object will | |
1018 // not otherwise be greyed and would be incorrectly swept up. | |
1019 // Note that if this object contains references, the writing | |
1020 // of those references will dirty the card containing this object | |
1021 // allowing the object to be blackened (and its references scanned) | |
1022 // either during a preclean phase or at the final checkpoint. | |
1023 if (res != NULL) { | |
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1024 // We may block here with an uninitialized object with |
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1025 // its mark-bit or P-bits not yet set. Such objects need |
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1026 // to be safely navigable by block_start(). |
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1027 assert(oop(res)->klass_or_null() == NULL, "Object should be uninitialized here."); |
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1028 assert(!((FreeChunk*)res)->is_free(), "Error, block will look free but show wrong size"); |
0 | 1029 collector()->direct_allocated(res, adjustedSize); |
1030 _direct_allocated_words += adjustedSize; | |
1031 // allocation counters | |
1032 NOT_PRODUCT( | |
1033 _numObjectsAllocated++; | |
1034 _numWordsAllocated += (int)adjustedSize; | |
1035 ) | |
1036 } | |
1037 return res; | |
1038 } | |
1039 | |
1040 // In the case of direct allocation by mutators in a generation that | |
1041 // is being concurrently collected, the object must be allocated | |
1042 // live (grey) if the background collector has started marking. | |
1043 // This is necessary because the marker may | |
1044 // have passed this address and consequently this object will | |
1045 // not otherwise be greyed and would be incorrectly swept up. | |
1046 // Note that if this object contains references, the writing | |
1047 // of those references will dirty the card containing this object | |
1048 // allowing the object to be blackened (and its references scanned) | |
1049 // either during a preclean phase or at the final checkpoint. | |
1050 void CMSCollector::direct_allocated(HeapWord* start, size_t size) { | |
1051 assert(_markBitMap.covers(start, size), "Out of bounds"); | |
1052 if (_collectorState >= Marking) { | |
1053 MutexLockerEx y(_markBitMap.lock(), | |
1054 Mutex::_no_safepoint_check_flag); | |
1055 // [see comments preceding SweepClosure::do_blk() below for details] | |
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1056 // |
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1057 // Can the P-bits be deleted now? JJJ |
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1058 // |
0 | 1059 // 1. need to mark the object as live so it isn't collected |
1060 // 2. need to mark the 2nd bit to indicate the object may be uninitialized | |
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1061 // 3. need to mark the end of the object so marking, precleaning or sweeping |
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1062 // can skip over uninitialized or unparsable objects. An allocated |
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1063 // object is considered uninitialized for our purposes as long as |
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1064 // its klass word is NULL. All old gen objects are parsable |
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1065 // as soon as they are initialized.) |
0 | 1066 _markBitMap.mark(start); // object is live |
1067 _markBitMap.mark(start + 1); // object is potentially uninitialized? | |
1068 _markBitMap.mark(start + size - 1); | |
1069 // mark end of object | |
1070 } | |
1071 // check that oop looks uninitialized | |
187 | 1072 assert(oop(start)->klass_or_null() == NULL, "_klass should be NULL"); |
0 | 1073 } |
1074 | |
1075 void CMSCollector::promoted(bool par, HeapWord* start, | |
1076 bool is_obj_array, size_t obj_size) { | |
1077 assert(_markBitMap.covers(start), "Out of bounds"); | |
1078 // See comment in direct_allocated() about when objects should | |
1079 // be allocated live. | |
1080 if (_collectorState >= Marking) { | |
1081 // we already hold the marking bit map lock, taken in | |
1082 // the prologue | |
1083 if (par) { | |
1084 _markBitMap.par_mark(start); | |
1085 } else { | |
1086 _markBitMap.mark(start); | |
1087 } | |
1088 // We don't need to mark the object as uninitialized (as | |
1089 // in direct_allocated above) because this is being done with the | |
1090 // world stopped and the object will be initialized by the | |
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1091 // time the marking, precleaning or sweeping get to look at it. |
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1092 // But see the code for copying objects into the CMS generation, |
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1093 // where we need to ensure that concurrent readers of the |
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1094 // block offset table are able to safely navigate a block that |
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1095 // is in flux from being free to being allocated (and in |
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1096 // transition while being copied into) and subsequently |
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1097 // becoming a bona-fide object when the copy/promotion is complete. |
0 | 1098 assert(SafepointSynchronize::is_at_safepoint(), |
1099 "expect promotion only at safepoints"); | |
1100 | |
1101 if (_collectorState < Sweeping) { | |
1102 // Mark the appropriate cards in the modUnionTable, so that | |
1103 // this object gets scanned before the sweep. If this is | |
1104 // not done, CMS generation references in the object might | |
1105 // not get marked. | |
1106 // For the case of arrays, which are otherwise precisely | |
1107 // marked, we need to dirty the entire array, not just its head. | |
1108 if (is_obj_array) { | |
1109 // The [par_]mark_range() method expects mr.end() below to | |
1110 // be aligned to the granularity of a bit's representation | |
1111 // in the heap. In the case of the MUT below, that's a | |
1112 // card size. | |
1113 MemRegion mr(start, | |
1114 (HeapWord*)round_to((intptr_t)(start + obj_size), | |
1115 CardTableModRefBS::card_size /* bytes */)); | |
1116 if (par) { | |
1117 _modUnionTable.par_mark_range(mr); | |
1118 } else { | |
1119 _modUnionTable.mark_range(mr); | |
1120 } | |
1121 } else { // not an obj array; we can just mark the head | |
1122 if (par) { | |
1123 _modUnionTable.par_mark(start); | |
1124 } else { | |
1125 _modUnionTable.mark(start); | |
1126 } | |
1127 } | |
1128 } | |
1129 } | |
1130 } | |
1131 | |
1132 static inline size_t percent_of_space(Space* space, HeapWord* addr) | |
1133 { | |
1134 size_t delta = pointer_delta(addr, space->bottom()); | |
1135 return (size_t)(delta * 100.0 / (space->capacity() / HeapWordSize)); | |
1136 } | |
1137 | |
1138 void CMSCollector::icms_update_allocation_limits() | |
1139 { | |
1140 Generation* gen0 = GenCollectedHeap::heap()->get_gen(0); | |
1141 EdenSpace* eden = gen0->as_DefNewGeneration()->eden(); | |
1142 | |
1143 const unsigned int duty_cycle = stats().icms_update_duty_cycle(); | |
1144 if (CMSTraceIncrementalPacing) { | |
1145 stats().print(); | |
1146 } | |
1147 | |
1148 assert(duty_cycle <= 100, "invalid duty cycle"); | |
1149 if (duty_cycle != 0) { | |
1150 // The duty_cycle is a percentage between 0 and 100; convert to words and | |
1151 // then compute the offset from the endpoints of the space. | |
1152 size_t free_words = eden->free() / HeapWordSize; | |
1153 double free_words_dbl = (double)free_words; | |
1154 size_t duty_cycle_words = (size_t)(free_words_dbl * duty_cycle / 100.0); | |
1155 size_t offset_words = (free_words - duty_cycle_words) / 2; | |
1156 | |
1157 _icms_start_limit = eden->top() + offset_words; | |
1158 _icms_stop_limit = eden->end() - offset_words; | |
1159 | |
1160 // The limits may be adjusted (shifted to the right) by | |
1161 // CMSIncrementalOffset, to allow the application more mutator time after a | |
1162 // young gen gc (when all mutators were stopped) and before CMS starts and | |
1163 // takes away one or more cpus. | |
1164 if (CMSIncrementalOffset != 0) { | |
1165 double adjustment_dbl = free_words_dbl * CMSIncrementalOffset / 100.0; | |
1166 size_t adjustment = (size_t)adjustment_dbl; | |
1167 HeapWord* tmp_stop = _icms_stop_limit + adjustment; | |
1168 if (tmp_stop > _icms_stop_limit && tmp_stop < eden->end()) { | |
1169 _icms_start_limit += adjustment; | |
1170 _icms_stop_limit = tmp_stop; | |
1171 } | |
1172 } | |
1173 } | |
1174 if (duty_cycle == 0 || (_icms_start_limit == _icms_stop_limit)) { | |
1175 _icms_start_limit = _icms_stop_limit = eden->end(); | |
1176 } | |
1177 | |
1178 // Install the new start limit. | |
1179 eden->set_soft_end(_icms_start_limit); | |
1180 | |
1181 if (CMSTraceIncrementalMode) { | |
1182 gclog_or_tty->print(" icms alloc limits: " | |
1183 PTR_FORMAT "," PTR_FORMAT | |
1184 " (" SIZE_FORMAT "%%," SIZE_FORMAT "%%) ", | |
1185 _icms_start_limit, _icms_stop_limit, | |
1186 percent_of_space(eden, _icms_start_limit), | |
1187 percent_of_space(eden, _icms_stop_limit)); | |
1188 if (Verbose) { | |
1189 gclog_or_tty->print("eden: "); | |
1190 eden->print_on(gclog_or_tty); | |
1191 } | |
1192 } | |
1193 } | |
1194 | |
1195 // Any changes here should try to maintain the invariant | |
1196 // that if this method is called with _icms_start_limit | |
1197 // and _icms_stop_limit both NULL, then it should return NULL | |
1198 // and not notify the icms thread. | |
1199 HeapWord* | |
1200 CMSCollector::allocation_limit_reached(Space* space, HeapWord* top, | |
1201 size_t word_size) | |
1202 { | |
1203 // A start_limit equal to end() means the duty cycle is 0, so treat that as a | |
1204 // nop. | |
1205 if (CMSIncrementalMode && _icms_start_limit != space->end()) { | |
1206 if (top <= _icms_start_limit) { | |
1207 if (CMSTraceIncrementalMode) { | |
1208 space->print_on(gclog_or_tty); | |
1209 gclog_or_tty->stamp(); | |
1210 gclog_or_tty->print_cr(" start limit top=" PTR_FORMAT | |
1211 ", new limit=" PTR_FORMAT | |
1212 " (" SIZE_FORMAT "%%)", | |
1213 top, _icms_stop_limit, | |
1214 percent_of_space(space, _icms_stop_limit)); | |
1215 } | |
1216 ConcurrentMarkSweepThread::start_icms(); | |
1217 assert(top < _icms_stop_limit, "Tautology"); | |
1218 if (word_size < pointer_delta(_icms_stop_limit, top)) { | |
1219 return _icms_stop_limit; | |
1220 } | |
1221 | |
1222 // The allocation will cross both the _start and _stop limits, so do the | |
1223 // stop notification also and return end(). | |
1224 if (CMSTraceIncrementalMode) { | |
1225 space->print_on(gclog_or_tty); | |
1226 gclog_or_tty->stamp(); | |
1227 gclog_or_tty->print_cr(" +stop limit top=" PTR_FORMAT | |
1228 ", new limit=" PTR_FORMAT | |
1229 " (" SIZE_FORMAT "%%)", | |
1230 top, space->end(), | |
1231 percent_of_space(space, space->end())); | |
1232 } | |
1233 ConcurrentMarkSweepThread::stop_icms(); | |
1234 return space->end(); | |
1235 } | |
1236 | |
1237 if (top <= _icms_stop_limit) { | |
1238 if (CMSTraceIncrementalMode) { | |
1239 space->print_on(gclog_or_tty); | |
1240 gclog_or_tty->stamp(); | |
1241 gclog_or_tty->print_cr(" stop limit top=" PTR_FORMAT | |
1242 ", new limit=" PTR_FORMAT | |
1243 " (" SIZE_FORMAT "%%)", | |
1244 top, space->end(), | |
1245 percent_of_space(space, space->end())); | |
1246 } | |
1247 ConcurrentMarkSweepThread::stop_icms(); | |
1248 return space->end(); | |
1249 } | |
1250 | |
1251 if (CMSTraceIncrementalMode) { | |
1252 space->print_on(gclog_or_tty); | |
1253 gclog_or_tty->stamp(); | |
1254 gclog_or_tty->print_cr(" end limit top=" PTR_FORMAT | |
1255 ", new limit=" PTR_FORMAT, | |
1256 top, NULL); | |
1257 } | |
1258 } | |
1259 | |
1260 return NULL; | |
1261 } | |
1262 | |
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1263 oop ConcurrentMarkSweepGeneration::promote(oop obj, size_t obj_size) { |
0 | 1264 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in"); |
1265 // allocate, copy and if necessary update promoinfo -- | |
1266 // delegate to underlying space. | |
1267 assert_lock_strong(freelistLock()); | |
1268 | |
1269 #ifndef PRODUCT | |
1270 if (Universe::heap()->promotion_should_fail()) { | |
1271 return NULL; | |
1272 } | |
1273 #endif // #ifndef PRODUCT | |
1274 | |
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1275 oop res = _cmsSpace->promote(obj, obj_size); |
0 | 1276 if (res == NULL) { |
1277 // expand and retry | |
1278 size_t s = _cmsSpace->expansionSpaceRequired(obj_size); // HeapWords | |
1279 expand(s*HeapWordSize, MinHeapDeltaBytes, | |
1280 CMSExpansionCause::_satisfy_promotion); | |
1281 // Since there's currently no next generation, we don't try to promote | |
1282 // into a more senior generation. | |
1283 assert(next_gen() == NULL, "assumption, based upon which no attempt " | |
1284 "is made to pass on a possibly failing " | |
1285 "promotion to next generation"); | |
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1286 res = _cmsSpace->promote(obj, obj_size); |
0 | 1287 } |
1288 if (res != NULL) { | |
1289 // See comment in allocate() about when objects should | |
1290 // be allocated live. | |
1291 assert(obj->is_oop(), "Will dereference klass pointer below"); | |
1292 collector()->promoted(false, // Not parallel | |
1293 (HeapWord*)res, obj->is_objArray(), obj_size); | |
1294 // promotion counters | |
1295 NOT_PRODUCT( | |
1296 _numObjectsPromoted++; | |
1297 _numWordsPromoted += | |
1298 (int)(CompactibleFreeListSpace::adjustObjectSize(obj->size())); | |
1299 ) | |
1300 } | |
1301 return res; | |
1302 } | |
1303 | |
1304 | |
1305 HeapWord* | |
1306 ConcurrentMarkSweepGeneration::allocation_limit_reached(Space* space, | |
1307 HeapWord* top, | |
1308 size_t word_sz) | |
1309 { | |
1310 return collector()->allocation_limit_reached(space, top, word_sz); | |
1311 } | |
1312 | |
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1313 // IMPORTANT: Notes on object size recognition in CMS. |
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1314 // --------------------------------------------------- |
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1315 // A block of storage in the CMS generation is always in |
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1316 // one of three states. A free block (FREE), an allocated |
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1317 // object (OBJECT) whose size() method reports the correct size, |
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1318 // and an intermediate state (TRANSIENT) in which its size cannot |
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1319 // be accurately determined. |
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1320 // STATE IDENTIFICATION: (32 bit and 64 bit w/o COOPS) |
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1321 // ----------------------------------------------------- |
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1322 // FREE: klass_word & 1 == 1; mark_word holds block size |
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1323 // |
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1324 // OBJECT: klass_word installed; klass_word != 0 && klass_word & 1 == 0; |
1716
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1325 // obj->size() computes correct size |
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1326 // |
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1327 // TRANSIENT: klass_word == 0; size is indeterminate until we become an OBJECT |
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1328 // |
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1329 // STATE IDENTIFICATION: (64 bit+COOPS) |
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1330 // ------------------------------------ |
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1331 // FREE: mark_word & CMS_FREE_BIT == 1; mark_word & ~CMS_FREE_BIT gives block_size |
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1332 // |
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1333 // OBJECT: klass_word installed; klass_word != 0; |
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1334 // obj->size() computes correct size |
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1335 // |
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1336 // TRANSIENT: klass_word == 0; size is indeterminate until we become an OBJECT |
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1337 // |
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1338 // |
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1339 // STATE TRANSITION DIAGRAM |
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1340 // |
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1341 // mut / parnew mut / parnew |
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1342 // FREE --------------------> TRANSIENT ---------------------> OBJECT --| |
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1343 // ^ | |
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1344 // |------------------------ DEAD <------------------------------------| |
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1345 // sweep mut |
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1346 // |
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1347 // While a block is in TRANSIENT state its size cannot be determined |
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1348 // so readers will either need to come back later or stall until |
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1349 // the size can be determined. Note that for the case of direct |
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1350 // allocation, P-bits, when available, may be used to determine the |
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1351 // size of an object that may not yet have been initialized. |
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1352 |
0 | 1353 // Things to support parallel young-gen collection. |
1354 oop | |
1355 ConcurrentMarkSweepGeneration::par_promote(int thread_num, | |
1356 oop old, markOop m, | |
1357 size_t word_sz) { | |
1358 #ifndef PRODUCT | |
1359 if (Universe::heap()->promotion_should_fail()) { | |
1360 return NULL; | |
1361 } | |
1362 #endif // #ifndef PRODUCT | |
1363 | |
1364 CMSParGCThreadState* ps = _par_gc_thread_states[thread_num]; | |
1365 PromotionInfo* promoInfo = &ps->promo; | |
1366 // if we are tracking promotions, then first ensure space for | |
1367 // promotion (including spooling space for saving header if necessary). | |
1368 // then allocate and copy, then track promoted info if needed. | |
1369 // When tracking (see PromotionInfo::track()), the mark word may | |
1370 // be displaced and in this case restoration of the mark word | |
1371 // occurs in the (oop_since_save_marks_)iterate phase. | |
1372 if (promoInfo->tracking() && !promoInfo->ensure_spooling_space()) { | |
1373 // Out of space for allocating spooling buffers; | |
1374 // try expanding and allocating spooling buffers. | |
1375 if (!expand_and_ensure_spooling_space(promoInfo)) { | |
1376 return NULL; | |
1377 } | |
1378 } | |
1379 assert(promoInfo->has_spooling_space(), "Control point invariant"); | |
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1380 const size_t alloc_sz = CompactibleFreeListSpace::adjustObjectSize(word_sz); |
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1381 HeapWord* obj_ptr = ps->lab.alloc(alloc_sz); |
0 | 1382 if (obj_ptr == NULL) { |
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1383 obj_ptr = expand_and_par_lab_allocate(ps, alloc_sz); |
0 | 1384 if (obj_ptr == NULL) { |
1385 return NULL; | |
1386 } | |
1387 } | |
1388 oop obj = oop(obj_ptr); | |
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1389 OrderAccess::storestore(); |
187 | 1390 assert(obj->klass_or_null() == NULL, "Object should be uninitialized here."); |
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1391 assert(!((FreeChunk*)obj_ptr)->is_free(), "Error, block will look free but show wrong size"); |
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1392 // IMPORTANT: See note on object initialization for CMS above. |
0 | 1393 // Otherwise, copy the object. Here we must be careful to insert the |
1394 // klass pointer last, since this marks the block as an allocated object. | |
187 | 1395 // Except with compressed oops it's the mark word. |
0 | 1396 HeapWord* old_ptr = (HeapWord*)old; |
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1397 // Restore the mark word copied above. |
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1398 obj->set_mark(m); |
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1399 assert(obj->klass_or_null() == NULL, "Object should be uninitialized here."); |
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1400 assert(!((FreeChunk*)obj_ptr)->is_free(), "Error, block will look free but show wrong size"); |
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1401 OrderAccess::storestore(); |
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1402 |
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1403 if (UseCompressedKlassPointers) { |
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1404 // Copy gap missed by (aligned) header size calculation below |
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1405 obj->set_klass_gap(old->klass_gap()); |
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1406 } |
0 | 1407 if (word_sz > (size_t)oopDesc::header_size()) { |
1408 Copy::aligned_disjoint_words(old_ptr + oopDesc::header_size(), | |
1409 obj_ptr + oopDesc::header_size(), | |
1410 word_sz - oopDesc::header_size()); | |
1411 } | |
187 | 1412 |
0 | 1413 // Now we can track the promoted object, if necessary. We take care |
1521 | 1414 // to delay the transition from uninitialized to full object |
0 | 1415 // (i.e., insertion of klass pointer) until after, so that it |
1416 // atomically becomes a promoted object. | |
1417 if (promoInfo->tracking()) { | |
1418 promoInfo->track((PromotedObject*)obj, old->klass()); | |
1419 } | |
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1420 assert(obj->klass_or_null() == NULL, "Object should be uninitialized here."); |
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1421 assert(!((FreeChunk*)obj_ptr)->is_free(), "Error, block will look free but show wrong size"); |
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1422 assert(old->is_oop(), "Will use and dereference old klass ptr below"); |
187 | 1423 |
1424 // Finally, install the klass pointer (this should be volatile). | |
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1425 OrderAccess::storestore(); |
0 | 1426 obj->set_klass(old->klass()); |
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1427 // We should now be able to calculate the right size for this object |
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1428 assert(obj->is_oop() && obj->size() == (int)word_sz, "Error, incorrect size computed for promoted object"); |
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1429 |
0 | 1430 collector()->promoted(true, // parallel |
1431 obj_ptr, old->is_objArray(), word_sz); | |
1432 | |
1433 NOT_PRODUCT( | |
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1434 Atomic::inc_ptr(&_numObjectsPromoted); |
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1435 Atomic::add_ptr(alloc_sz, &_numWordsPromoted); |
0 | 1436 ) |
1437 | |
1438 return obj; | |
1439 } | |
1440 | |
1441 void | |
1442 ConcurrentMarkSweepGeneration:: | |
1443 par_promote_alloc_undo(int thread_num, | |
1444 HeapWord* obj, size_t word_sz) { | |
1445 // CMS does not support promotion undo. | |
1446 ShouldNotReachHere(); | |
1447 } | |
1448 | |
1449 void | |
1450 ConcurrentMarkSweepGeneration:: | |
1451 par_promote_alloc_done(int thread_num) { | |
1452 CMSParGCThreadState* ps = _par_gc_thread_states[thread_num]; | |
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1453 ps->lab.retire(thread_num); |
0 | 1454 } |
1455 | |
1456 void | |
1457 ConcurrentMarkSweepGeneration:: | |
1458 par_oop_since_save_marks_iterate_done(int thread_num) { | |
1459 CMSParGCThreadState* ps = _par_gc_thread_states[thread_num]; | |
1460 ParScanWithoutBarrierClosure* dummy_cl = NULL; | |
1461 ps->promo.promoted_oops_iterate_nv(dummy_cl); | |
1462 } | |
1463 | |
1464 bool ConcurrentMarkSweepGeneration::should_collect(bool full, | |
1465 size_t size, | |
1466 bool tlab) | |
1467 { | |
1468 // We allow a STW collection only if a full | |
1469 // collection was requested. | |
1470 return full || should_allocate(size, tlab); // FIX ME !!! | |
1471 // This and promotion failure handling are connected at the | |
1472 // hip and should be fixed by untying them. | |
1473 } | |
1474 | |
1475 bool CMSCollector::shouldConcurrentCollect() { | |
1476 if (_full_gc_requested) { | |
1477 if (Verbose && PrintGCDetails) { | |
1478 gclog_or_tty->print_cr("CMSCollector: collect because of explicit " | |
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1479 " gc request (or gc_locker)"); |
0 | 1480 } |
1481 return true; | |
1482 } | |
1483 | |
1484 // For debugging purposes, change the type of collection. | |
1485 // If the rotation is not on the concurrent collection | |
1486 // type, don't start a concurrent collection. | |
1487 NOT_PRODUCT( | |
1488 if (RotateCMSCollectionTypes && | |
1489 (_cmsGen->debug_collection_type() != | |
1490 ConcurrentMarkSweepGeneration::Concurrent_collection_type)) { | |
1491 assert(_cmsGen->debug_collection_type() != | |
1492 ConcurrentMarkSweepGeneration::Unknown_collection_type, | |
1493 "Bad cms collection type"); | |
1494 return false; | |
1495 } | |
1496 ) | |
1497 | |
1498 FreelistLocker x(this); | |
1499 // ------------------------------------------------------------------ | |
1500 // Print out lots of information which affects the initiation of | |
1501 // a collection. | |
1502 if (PrintCMSInitiationStatistics && stats().valid()) { | |
1503 gclog_or_tty->print("CMSCollector shouldConcurrentCollect: "); | |
1504 gclog_or_tty->stamp(); | |
1505 gclog_or_tty->print_cr(""); | |
1506 stats().print_on(gclog_or_tty); | |
1507 gclog_or_tty->print_cr("time_until_cms_gen_full %3.7f", | |
1508 stats().time_until_cms_gen_full()); | |
1509 gclog_or_tty->print_cr("free="SIZE_FORMAT, _cmsGen->free()); | |
1510 gclog_or_tty->print_cr("contiguous_available="SIZE_FORMAT, | |
1511 _cmsGen->contiguous_available()); | |
1512 gclog_or_tty->print_cr("promotion_rate=%g", stats().promotion_rate()); | |
1513 gclog_or_tty->print_cr("cms_allocation_rate=%g", stats().cms_allocation_rate()); | |
1514 gclog_or_tty->print_cr("occupancy=%3.7f", _cmsGen->occupancy()); | |
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1515 gclog_or_tty->print_cr("initiatingOccupancy=%3.7f", _cmsGen->initiating_occupancy()); |
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1516 gclog_or_tty->print_cr("metadata initialized %d", |
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1517 MetaspaceGC::should_concurrent_collect()); |
0 | 1518 } |
1519 // ------------------------------------------------------------------ | |
1520 | |
1521 // If the estimated time to complete a cms collection (cms_duration()) | |
1522 // is less than the estimated time remaining until the cms generation | |
1523 // is full, start a collection. | |
1524 if (!UseCMSInitiatingOccupancyOnly) { | |
1525 if (stats().valid()) { | |
1526 if (stats().time_until_cms_start() == 0.0) { | |
1527 return true; | |
1528 } | |
1529 } else { | |
1530 // We want to conservatively collect somewhat early in order | |
1531 // to try and "bootstrap" our CMS/promotion statistics; | |
1532 // this branch will not fire after the first successful CMS | |
1533 // collection because the stats should then be valid. | |
1534 if (_cmsGen->occupancy() >= _bootstrap_occupancy) { | |
1535 if (Verbose && PrintGCDetails) { | |
1536 gclog_or_tty->print_cr( | |
1537 " CMSCollector: collect for bootstrapping statistics:" | |
1538 " occupancy = %f, boot occupancy = %f", _cmsGen->occupancy(), | |
1539 _bootstrap_occupancy); | |
1540 } | |
1541 return true; | |
1542 } | |
1543 } | |
1544 } | |
1545 | |
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1546 // Otherwise, we start a collection cycle if |
0 | 1547 // old gen want a collection cycle started. Each may use |
1548 // an appropriate criterion for making this decision. | |
1549 // XXX We need to make sure that the gen expansion | |
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1550 // criterion dovetails well with this. XXX NEED TO FIX THIS |
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1551 if (_cmsGen->should_concurrent_collect()) { |
0 | 1552 if (Verbose && PrintGCDetails) { |
1553 gclog_or_tty->print_cr("CMS old gen initiated"); | |
1554 } | |
1555 return true; | |
1556 } | |
1557 | |
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1558 // We start a collection if we believe an incremental collection may fail; |
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1559 // this is not likely to be productive in practice because it's probably too |
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1560 // late anyway. |
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1561 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
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1562 assert(gch->collector_policy()->is_two_generation_policy(), |
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1563 "You may want to check the correctness of the following"); |
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1564 if (gch->incremental_collection_will_fail(true /* consult_young */)) { |
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1565 if (Verbose && PrintGCDetails) { |
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1566 gclog_or_tty->print("CMSCollector: collect because incremental collection will fail "); |
0 | 1567 } |
1568 return true; | |
1569 } | |
1570 | |
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1571 if (MetaspaceGC::should_concurrent_collect()) { |
94
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1572 if (Verbose && PrintGCDetails) { |
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1573 gclog_or_tty->print("CMSCollector: collect for metadata allocation "); |
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1574 } |
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1575 return true; |
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1576 } |
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1577 |
0 | 1578 return false; |
1579 } | |
1580 | |
1581 // Clear _expansion_cause fields of constituent generations | |
1582 void CMSCollector::clear_expansion_cause() { | |
1583 _cmsGen->clear_expansion_cause(); | |
1584 } | |
1585 | |
94
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1586 // We should be conservative in starting a collection cycle. To |
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1587 // start too eagerly runs the risk of collecting too often in the |
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1588 // extreme. To collect too rarely falls back on full collections, |
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1589 // which works, even if not optimum in terms of concurrent work. |
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1590 // As a work around for too eagerly collecting, use the flag |
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1591 // UseCMSInitiatingOccupancyOnly. This also has the advantage of |
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1592 // giving the user an easily understandable way of controlling the |
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1593 // collections. |
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1594 // We want to start a new collection cycle if any of the following |
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1595 // conditions hold: |
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1596 // . our current occupancy exceeds the configured initiating occupancy |
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1597 // for this generation, or |
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1598 // . we recently needed to expand this space and have not, since that |
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1599 // expansion, done a collection of this generation, or |
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1600 // . the underlying space believes that it may be a good idea to initiate |
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1601 // a concurrent collection (this may be based on criteria such as the |
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1602 // following: the space uses linear allocation and linear allocation is |
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1603 // going to fail, or there is believed to be excessive fragmentation in |
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1604 // the generation, etc... or ... |
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1605 // [.(currently done by CMSCollector::shouldConcurrentCollect() only for |
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1606 // the case of the old generation; see CR 6543076): |
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1607 // we may be approaching a point at which allocation requests may fail because |
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1608 // we will be out of sufficient free space given allocation rate estimates.] |
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1609 bool ConcurrentMarkSweepGeneration::should_concurrent_collect() const { |
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1610 |
0 | 1611 assert_lock_strong(freelistLock()); |
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1612 if (occupancy() > initiating_occupancy()) { |
0 | 1613 if (PrintGCDetails && Verbose) { |
1614 gclog_or_tty->print(" %s: collect because of occupancy %f / %f ", | |
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1615 short_name(), occupancy(), initiating_occupancy()); |
0 | 1616 } |
1617 return true; | |
1618 } | |
1619 if (UseCMSInitiatingOccupancyOnly) { | |
1620 return false; | |
1621 } | |
1622 if (expansion_cause() == CMSExpansionCause::_satisfy_allocation) { | |
1623 if (PrintGCDetails && Verbose) { | |
1624 gclog_or_tty->print(" %s: collect because expanded for allocation ", | |
1625 short_name()); | |
1626 } | |
1627 return true; | |
1628 } | |
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1629 if (_cmsSpace->should_concurrent_collect()) { |
0 | 1630 if (PrintGCDetails && Verbose) { |
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1631 gclog_or_tty->print(" %s: collect because cmsSpace says so ", |
0 | 1632 short_name()); |
1633 } | |
1634 return true; | |
1635 } | |
1636 return false; | |
1637 } | |
1638 | |
1639 void ConcurrentMarkSweepGeneration::collect(bool full, | |
1640 bool clear_all_soft_refs, | |
1641 size_t size, | |
1642 bool tlab) | |
1643 { | |
1644 collector()->collect(full, clear_all_soft_refs, size, tlab); | |
1645 } | |
1646 | |
1647 void CMSCollector::collect(bool full, | |
1648 bool clear_all_soft_refs, | |
1649 size_t size, | |
1650 bool tlab) | |
1651 { | |
1652 if (!UseCMSCollectionPassing && _collectorState > Idling) { | |
1653 // For debugging purposes skip the collection if the state | |
1654 // is not currently idle | |
1655 if (TraceCMSState) { | |
1656 gclog_or_tty->print_cr("Thread " INTPTR_FORMAT " skipped full:%d CMS state %d", | |
1657 Thread::current(), full, _collectorState); | |
1658 } | |
1659 return; | |
1660 } | |
1661 | |
1662 // The following "if" branch is present for defensive reasons. | |
1663 // In the current uses of this interface, it can be replaced with: | |
1664 // assert(!GC_locker.is_active(), "Can't be called otherwise"); | |
1665 // But I am not placing that assert here to allow future | |
1666 // generality in invoking this interface. | |
1667 if (GC_locker::is_active()) { | |
1668 // A consistency test for GC_locker | |
1669 assert(GC_locker::needs_gc(), "Should have been set already"); | |
1670 // Skip this foreground collection, instead | |
1671 // expanding the heap if necessary. | |
1672 // Need the free list locks for the call to free() in compute_new_size() | |
1673 compute_new_size(); | |
1674 return; | |
1675 } | |
1676 acquire_control_and_collect(full, clear_all_soft_refs); | |
1677 _full_gcs_since_conc_gc++; | |
1678 | |
1679 } | |
1680 | |
1681 void CMSCollector::request_full_gc(unsigned int full_gc_count) { | |
1682 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
1683 unsigned int gc_count = gch->total_full_collections(); | |
1684 if (gc_count == full_gc_count) { | |
1685 MutexLockerEx y(CGC_lock, Mutex::_no_safepoint_check_flag); | |
1686 _full_gc_requested = true; | |
1687 CGC_lock->notify(); // nudge CMS thread | |
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1688 } else { |
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1689 assert(gc_count > full_gc_count, "Error: causal loop"); |
0 | 1690 } |
1691 } | |
1692 | |
1693 | |
1694 // The foreground and background collectors need to coordinate in order | |
1695 // to make sure that they do not mutually interfere with CMS collections. | |
1696 // When a background collection is active, | |
1697 // the foreground collector may need to take over (preempt) and | |
1698 // synchronously complete an ongoing collection. Depending on the | |
1699 // frequency of the background collections and the heap usage | |
1700 // of the application, this preemption can be seldom or frequent. | |
1701 // There are only certain | |
1702 // points in the background collection that the "collection-baton" | |
1703 // can be passed to the foreground collector. | |
1704 // | |
1705 // The foreground collector will wait for the baton before | |
1706 // starting any part of the collection. The foreground collector | |
1707 // will only wait at one location. | |
1708 // | |
1709 // The background collector will yield the baton before starting a new | |
1710 // phase of the collection (e.g., before initial marking, marking from roots, | |
1711 // precleaning, final re-mark, sweep etc.) This is normally done at the head | |
1712 // of the loop which switches the phases. The background collector does some | |
1713 // of the phases (initial mark, final re-mark) with the world stopped. | |
1714 // Because of locking involved in stopping the world, | |
1715 // the foreground collector should not block waiting for the background | |
1716 // collector when it is doing a stop-the-world phase. The background | |
1717 // collector will yield the baton at an additional point just before | |
1718 // it enters a stop-the-world phase. Once the world is stopped, the | |
1719 // background collector checks the phase of the collection. If the | |
1720 // phase has not changed, it proceeds with the collection. If the | |
1721 // phase has changed, it skips that phase of the collection. See | |
1722 // the comments on the use of the Heap_lock in collect_in_background(). | |
1723 // | |
1724 // Variable used in baton passing. | |
1725 // _foregroundGCIsActive - Set to true by the foreground collector when | |
1726 // it wants the baton. The foreground clears it when it has finished | |
1727 // the collection. | |
1728 // _foregroundGCShouldWait - Set to true by the background collector | |
1729 // when it is running. The foreground collector waits while | |
1730 // _foregroundGCShouldWait is true. | |
1731 // CGC_lock - monitor used to protect access to the above variables | |
1732 // and to notify the foreground and background collectors. | |
1733 // _collectorState - current state of the CMS collection. | |
1734 // | |
1735 // The foreground collector | |
1736 // acquires the CGC_lock | |
1737 // sets _foregroundGCIsActive | |
1738 // waits on the CGC_lock for _foregroundGCShouldWait to be false | |
1739 // various locks acquired in preparation for the collection | |
1740 // are released so as not to block the background collector | |
1741 // that is in the midst of a collection | |
1742 // proceeds with the collection | |
1743 // clears _foregroundGCIsActive | |
1744 // returns | |
1745 // | |
1746 // The background collector in a loop iterating on the phases of the | |
1747 // collection | |
1748 // acquires the CGC_lock | |
1749 // sets _foregroundGCShouldWait | |
1750 // if _foregroundGCIsActive is set | |
1751 // clears _foregroundGCShouldWait, notifies _CGC_lock | |
1752 // waits on _CGC_lock for _foregroundGCIsActive to become false | |
1753 // and exits the loop. | |
1754 // otherwise | |
1755 // proceed with that phase of the collection | |
1756 // if the phase is a stop-the-world phase, | |
1757 // yield the baton once more just before enqueueing | |
1758 // the stop-world CMS operation (executed by the VM thread). | |
1759 // returns after all phases of the collection are done | |
1760 // | |
1761 | |
1762 void CMSCollector::acquire_control_and_collect(bool full, | |
1763 bool clear_all_soft_refs) { | |
1764 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); | |
1765 assert(!Thread::current()->is_ConcurrentGC_thread(), | |
1766 "shouldn't try to acquire control from self!"); | |
1767 | |
1768 // Start the protocol for acquiring control of the | |
1769 // collection from the background collector (aka CMS thread). | |
1770 assert(ConcurrentMarkSweepThread::vm_thread_has_cms_token(), | |
1771 "VM thread should have CMS token"); | |
1772 // Remember the possibly interrupted state of an ongoing | |
1773 // concurrent collection | |
1774 CollectorState first_state = _collectorState; | |
1775 | |
1776 // Signal to a possibly ongoing concurrent collection that | |
1777 // we want to do a foreground collection. | |
1778 _foregroundGCIsActive = true; | |
1779 | |
1780 // Disable incremental mode during a foreground collection. | |
1781 ICMSDisabler icms_disabler; | |
1782 | |
1783 // release locks and wait for a notify from the background collector | |
1784 // releasing the locks in only necessary for phases which | |
1785 // do yields to improve the granularity of the collection. | |
1786 assert_lock_strong(bitMapLock()); | |
1787 // We need to lock the Free list lock for the space that we are | |
1788 // currently collecting. | |
1789 assert(haveFreelistLocks(), "Must be holding free list locks"); | |
1790 bitMapLock()->unlock(); | |
1791 releaseFreelistLocks(); | |
1792 { | |
1793 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
1794 if (_foregroundGCShouldWait) { | |
1795 // We are going to be waiting for action for the CMS thread; | |
1796 // it had better not be gone (for instance at shutdown)! | |
1797 assert(ConcurrentMarkSweepThread::cmst() != NULL, | |
1798 "CMS thread must be running"); | |
1799 // Wait here until the background collector gives us the go-ahead | |
1800 ConcurrentMarkSweepThread::clear_CMS_flag( | |
1801 ConcurrentMarkSweepThread::CMS_vm_has_token); // release token | |
1802 // Get a possibly blocked CMS thread going: | |
1803 // Note that we set _foregroundGCIsActive true above, | |
1804 // without protection of the CGC_lock. | |
1805 CGC_lock->notify(); | |
1806 assert(!ConcurrentMarkSweepThread::vm_thread_wants_cms_token(), | |
1807 "Possible deadlock"); | |
1808 while (_foregroundGCShouldWait) { | |
1809 // wait for notification | |
1810 CGC_lock->wait(Mutex::_no_safepoint_check_flag); | |
1811 // Possibility of delay/starvation here, since CMS token does | |
1812 // not know to give priority to VM thread? Actually, i think | |
1813 // there wouldn't be any delay/starvation, but the proof of | |
1814 // that "fact" (?) appears non-trivial. XXX 20011219YSR | |
1815 } | |
1816 ConcurrentMarkSweepThread::set_CMS_flag( | |
1817 ConcurrentMarkSweepThread::CMS_vm_has_token); | |
1818 } | |
1819 } | |
1820 // The CMS_token is already held. Get back the other locks. | |
1821 assert(ConcurrentMarkSweepThread::vm_thread_has_cms_token(), | |
1822 "VM thread should have CMS token"); | |
1823 getFreelistLocks(); | |
1824 bitMapLock()->lock_without_safepoint_check(); | |
1825 if (TraceCMSState) { | |
1826 gclog_or_tty->print_cr("CMS foreground collector has asked for control " | |
1827 INTPTR_FORMAT " with first state %d", Thread::current(), first_state); | |
1828 gclog_or_tty->print_cr(" gets control with state %d", _collectorState); | |
1829 } | |
1830 | |
1831 // Check if we need to do a compaction, or if not, whether | |
1832 // we need to start the mark-sweep from scratch. | |
1833 bool should_compact = false; | |
1834 bool should_start_over = false; | |
1835 decide_foreground_collection_type(clear_all_soft_refs, | |
1836 &should_compact, &should_start_over); | |
1837 | |
1838 NOT_PRODUCT( | |
1839 if (RotateCMSCollectionTypes) { | |
1840 if (_cmsGen->debug_collection_type() == | |
1841 ConcurrentMarkSweepGeneration::MSC_foreground_collection_type) { | |
1842 should_compact = true; | |
1843 } else if (_cmsGen->debug_collection_type() == | |
1844 ConcurrentMarkSweepGeneration::MS_foreground_collection_type) { | |
1845 should_compact = false; | |
1846 } | |
1847 } | |
1848 ) | |
1849 | |
1850 if (PrintGCDetails && first_state > Idling) { | |
1851 GCCause::Cause cause = GenCollectedHeap::heap()->gc_cause(); | |
1852 if (GCCause::is_user_requested_gc(cause) || | |
1853 GCCause::is_serviceability_requested_gc(cause)) { | |
1854 gclog_or_tty->print(" (concurrent mode interrupted)"); | |
1855 } else { | |
1856 gclog_or_tty->print(" (concurrent mode failure)"); | |
1857 } | |
1858 } | |
1859 | |
1860 if (should_compact) { | |
1861 // If the collection is being acquired from the background | |
1862 // collector, there may be references on the discovered | |
1863 // references lists that have NULL referents (being those | |
1864 // that were concurrently cleared by a mutator) or | |
1865 // that are no longer active (having been enqueued concurrently | |
1866 // by the mutator). | |
1867 // Scrub the list of those references because Mark-Sweep-Compact | |
1868 // code assumes referents are not NULL and that all discovered | |
1869 // Reference objects are active. | |
1870 ref_processor()->clean_up_discovered_references(); | |
1871 | |
1872 do_compaction_work(clear_all_soft_refs); | |
1873 | |
1874 // Has the GC time limit been exceeded? | |
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1875 DefNewGeneration* young_gen = _young_gen->as_DefNewGeneration(); |
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1876 size_t max_eden_size = young_gen->max_capacity() - |
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1877 young_gen->to()->capacity() - |
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1878 young_gen->from()->capacity(); |
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1879 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
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1880 GCCause::Cause gc_cause = gch->gc_cause(); |
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1881 size_policy()->check_gc_overhead_limit(_young_gen->used(), |
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1882 young_gen->eden()->used(), |
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1883 _cmsGen->max_capacity(), |
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1884 max_eden_size, |
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1885 full, |
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1886 gc_cause, |
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1887 gch->collector_policy()); |
0 | 1888 } else { |
1889 do_mark_sweep_work(clear_all_soft_refs, first_state, | |
1890 should_start_over); | |
1891 } | |
1892 // Reset the expansion cause, now that we just completed | |
1893 // a collection cycle. | |
1894 clear_expansion_cause(); | |
1895 _foregroundGCIsActive = false; | |
1896 return; | |
1897 } | |
1898 | |
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1899 // Resize the tenured generation |
0 | 1900 // after obtaining the free list locks for the |
1901 // two generations. | |
1902 void CMSCollector::compute_new_size() { | |
1903 assert_locked_or_safepoint(Heap_lock); | |
1904 FreelistLocker z(this); | |
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1905 MetaspaceGC::compute_new_size(); |
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1906 _cmsGen->compute_new_size_free_list(); |
0 | 1907 } |
1908 | |
1909 // A work method used by foreground collection to determine | |
1910 // what type of collection (compacting or not, continuing or fresh) | |
1911 // it should do. | |
1912 // NOTE: the intent is to make UseCMSCompactAtFullCollection | |
1913 // and CMSCompactWhenClearAllSoftRefs the default in the future | |
1914 // and do away with the flags after a suitable period. | |
1915 void CMSCollector::decide_foreground_collection_type( | |
1916 bool clear_all_soft_refs, bool* should_compact, | |
1917 bool* should_start_over) { | |
1918 // Normally, we'll compact only if the UseCMSCompactAtFullCollection | |
1919 // flag is set, and we have either requested a System.gc() or | |
1920 // the number of full gc's since the last concurrent cycle | |
1921 // has exceeded the threshold set by CMSFullGCsBeforeCompaction, | |
1922 // or if an incremental collection has failed | |
1923 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
1924 assert(gch->collector_policy()->is_two_generation_policy(), | |
1925 "You may want to check the correctness of the following"); | |
1926 // Inform cms gen if this was due to partial collection failing. | |
1927 // The CMS gen may use this fact to determine its expansion policy. | |
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1928 if (gch->incremental_collection_will_fail(false /* don't consult_young */)) { |
0 | 1929 assert(!_cmsGen->incremental_collection_failed(), |
1930 "Should have been noticed, reacted to and cleared"); | |
1931 _cmsGen->set_incremental_collection_failed(); | |
1932 } | |
1933 *should_compact = | |
1934 UseCMSCompactAtFullCollection && | |
1935 ((_full_gcs_since_conc_gc >= CMSFullGCsBeforeCompaction) || | |
1936 GCCause::is_user_requested_gc(gch->gc_cause()) || | |
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1937 gch->incremental_collection_will_fail(true /* consult_young */)); |
0 | 1938 *should_start_over = false; |
1939 if (clear_all_soft_refs && !*should_compact) { | |
1940 // We are about to do a last ditch collection attempt | |
1941 // so it would normally make sense to do a compaction | |
1942 // to reclaim as much space as possible. | |
1943 if (CMSCompactWhenClearAllSoftRefs) { | |
1944 // Default: The rationale is that in this case either | |
1945 // we are past the final marking phase, in which case | |
1946 // we'd have to start over, or so little has been done | |
1947 // that there's little point in saving that work. Compaction | |
1948 // appears to be the sensible choice in either case. | |
1949 *should_compact = true; | |
1950 } else { | |
1951 // We have been asked to clear all soft refs, but not to | |
1952 // compact. Make sure that we aren't past the final checkpoint | |
1953 // phase, for that is where we process soft refs. If we are already | |
1954 // past that phase, we'll need to redo the refs discovery phase and | |
1955 // if necessary clear soft refs that weren't previously | |
1956 // cleared. We do so by remembering the phase in which | |
1957 // we came in, and if we are past the refs processing | |
1958 // phase, we'll choose to just redo the mark-sweep | |
1959 // collection from scratch. | |
1960 if (_collectorState > FinalMarking) { | |
1961 // We are past the refs processing phase; | |
1962 // start over and do a fresh synchronous CMS cycle | |
1963 _collectorState = Resetting; // skip to reset to start new cycle | |
1964 reset(false /* == !asynch */); | |
1965 *should_start_over = true; | |
1966 } // else we can continue a possibly ongoing current cycle | |
1967 } | |
1968 } | |
1969 } | |
1970 | |
1971 // A work method used by the foreground collector to do | |
1972 // a mark-sweep-compact. | |
1973 void CMSCollector::do_compaction_work(bool clear_all_soft_refs) { | |
1974 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
1975 TraceTime t("CMS:MSC ", PrintGCDetails && Verbose, true, gclog_or_tty); | |
1976 if (PrintGC && Verbose && !(GCCause::is_user_requested_gc(gch->gc_cause()))) { | |
1977 gclog_or_tty->print_cr("Compact ConcurrentMarkSweepGeneration after %d " | |
1978 "collections passed to foreground collector", _full_gcs_since_conc_gc); | |
1979 } | |
1980 | |
1981 // Sample collection interval time and reset for collection pause. | |
1982 if (UseAdaptiveSizePolicy) { | |
1983 size_policy()->msc_collection_begin(); | |
1984 } | |
1985 | |
1986 // Temporarily widen the span of the weak reference processing to | |
1987 // the entire heap. | |
1988 MemRegion new_span(GenCollectedHeap::heap()->reserved_region()); | |
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1989 ReferenceProcessorSpanMutator rp_mut_span(ref_processor(), new_span); |
0 | 1990 // Temporarily, clear the "is_alive_non_header" field of the |
1991 // reference processor. | |
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1992 ReferenceProcessorIsAliveMutator rp_mut_closure(ref_processor(), NULL); |
0 | 1993 // Temporarily make reference _processing_ single threaded (non-MT). |
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1994 ReferenceProcessorMTProcMutator rp_mut_mt_processing(ref_processor(), false); |
0 | 1995 // Temporarily make refs discovery atomic |
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1996 ReferenceProcessorAtomicMutator rp_mut_atomic(ref_processor(), true); |
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1997 // Temporarily make reference _discovery_ single threaded (non-MT) |
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1998 ReferenceProcessorMTDiscoveryMutator rp_mut_discovery(ref_processor(), false); |
0 | 1999 |
2000 ref_processor()->set_enqueuing_is_done(false); | |
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2001 ref_processor()->enable_discovery(false /*verify_disabled*/, false /*check_no_refs*/); |
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2002 ref_processor()->setup_policy(clear_all_soft_refs); |
0 | 2003 // If an asynchronous collection finishes, the _modUnionTable is |
2004 // all clear. If we are assuming the collection from an asynchronous | |
2005 // collection, clear the _modUnionTable. | |
2006 assert(_collectorState != Idling || _modUnionTable.isAllClear(), | |
2007 "_modUnionTable should be clear if the baton was not passed"); | |
2008 _modUnionTable.clear_all(); | |
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2009 assert(_collectorState != Idling || _ct->klass_rem_set()->mod_union_is_clear(), |
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2010 "mod union for klasses should be clear if the baton was passed"); |
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2011 _ct->klass_rem_set()->clear_mod_union(); |
0 | 2012 |
2013 // We must adjust the allocation statistics being maintained | |
2014 // in the free list space. We do so by reading and clearing | |
2015 // the sweep timer and updating the block flux rate estimates below. | |
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2016 assert(!_intra_sweep_timer.is_active(), "_intra_sweep_timer should be inactive"); |
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2017 if (_inter_sweep_timer.is_active()) { |
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2018 _inter_sweep_timer.stop(); |
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2019 // Note that we do not use this sample to update the _inter_sweep_estimate. |
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2020 _cmsGen->cmsSpace()->beginSweepFLCensus((float)(_inter_sweep_timer.seconds()), |
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2021 _inter_sweep_estimate.padded_average(), |
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2022 _intra_sweep_estimate.padded_average()); |
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2023 } |
0 | 2024 |
2025 GenMarkSweep::invoke_at_safepoint(_cmsGen->level(), | |
2026 ref_processor(), clear_all_soft_refs); | |
2027 #ifdef ASSERT | |
2028 CompactibleFreeListSpace* cms_space = _cmsGen->cmsSpace(); | |
2029 size_t free_size = cms_space->free(); | |
2030 assert(free_size == | |
2031 pointer_delta(cms_space->end(), cms_space->compaction_top()) | |
2032 * HeapWordSize, | |
2033 "All the free space should be compacted into one chunk at top"); | |
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2034 assert(cms_space->dictionary()->total_chunk_size( |
0 | 2035 debug_only(cms_space->freelistLock())) == 0 || |
2036 cms_space->totalSizeInIndexedFreeLists() == 0, | |
2037 "All the free space should be in a single chunk"); | |
2038 size_t num = cms_space->totalCount(); | |
2039 assert((free_size == 0 && num == 0) || | |
2040 (free_size > 0 && (num == 1 || num == 2)), | |
2041 "There should be at most 2 free chunks after compaction"); | |
2042 #endif // ASSERT | |
2043 _collectorState = Resetting; | |
2044 assert(_restart_addr == NULL, | |
2045 "Should have been NULL'd before baton was passed"); | |
2046 reset(false /* == !asynch */); | |
2047 _cmsGen->reset_after_compaction(); | |
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2048 _concurrent_cycles_since_last_unload = 0; |
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2049 |
0 | 2050 // Clear any data recorded in the PLAB chunk arrays. |
2051 if (_survivor_plab_array != NULL) { | |
2052 reset_survivor_plab_arrays(); | |
2053 } | |
2054 | |
2055 // Adjust the per-size allocation stats for the next epoch. | |
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2056 _cmsGen->cmsSpace()->endSweepFLCensus(sweep_count() /* fake */); |
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2057 // Restart the "inter sweep timer" for the next epoch. |
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2058 _inter_sweep_timer.reset(); |
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2059 _inter_sweep_timer.start(); |
0 | 2060 |
2061 // Sample collection pause time and reset for collection interval. | |
2062 if (UseAdaptiveSizePolicy) { | |
2063 size_policy()->msc_collection_end(gch->gc_cause()); | |
2064 } | |
2065 | |
2066 // For a mark-sweep-compact, compute_new_size() will be called | |
2067 // in the heap's do_collection() method. | |
2068 } | |
2069 | |
2070 // A work method used by the foreground collector to do | |
2071 // a mark-sweep, after taking over from a possibly on-going | |
2072 // concurrent mark-sweep collection. | |
2073 void CMSCollector::do_mark_sweep_work(bool clear_all_soft_refs, | |
2074 CollectorState first_state, bool should_start_over) { | |
2075 if (PrintGC && Verbose) { | |
2076 gclog_or_tty->print_cr("Pass concurrent collection to foreground " | |
2077 "collector with count %d", | |
2078 _full_gcs_since_conc_gc); | |
2079 } | |
2080 switch (_collectorState) { | |
2081 case Idling: | |
2082 if (first_state == Idling || should_start_over) { | |
2083 // The background GC was not active, or should | |
2084 // restarted from scratch; start the cycle. | |
2085 _collectorState = InitialMarking; | |
2086 } | |
2087 // If first_state was not Idling, then a background GC | |
2088 // was in progress and has now finished. No need to do it | |
2089 // again. Leave the state as Idling. | |
2090 break; | |
2091 case Precleaning: | |
2092 // In the foreground case don't do the precleaning since | |
2093 // it is not done concurrently and there is extra work | |
2094 // required. | |
2095 _collectorState = FinalMarking; | |
2096 } | |
2097 collect_in_foreground(clear_all_soft_refs); | |
2098 | |
2099 // For a mark-sweep, compute_new_size() will be called | |
2100 // in the heap's do_collection() method. | |
2101 } | |
2102 | |
2103 | |
2104 void CMSCollector::getFreelistLocks() const { | |
2105 // Get locks for all free lists in all generations that this | |
2106 // collector is responsible for | |
2107 _cmsGen->freelistLock()->lock_without_safepoint_check(); | |
2108 } | |
2109 | |
2110 void CMSCollector::releaseFreelistLocks() const { | |
2111 // Release locks for all free lists in all generations that this | |
2112 // collector is responsible for | |
2113 _cmsGen->freelistLock()->unlock(); | |
2114 } | |
2115 | |
2116 bool CMSCollector::haveFreelistLocks() const { | |
2117 // Check locks for all free lists in all generations that this | |
2118 // collector is responsible for | |
2119 assert_lock_strong(_cmsGen->freelistLock()); | |
2120 PRODUCT_ONLY(ShouldNotReachHere()); | |
2121 return true; | |
2122 } | |
2123 | |
2124 // A utility class that is used by the CMS collector to | |
2125 // temporarily "release" the foreground collector from its | |
2126 // usual obligation to wait for the background collector to | |
2127 // complete an ongoing phase before proceeding. | |
2128 class ReleaseForegroundGC: public StackObj { | |
2129 private: | |
2130 CMSCollector* _c; | |
2131 public: | |
2132 ReleaseForegroundGC(CMSCollector* c) : _c(c) { | |
2133 assert(_c->_foregroundGCShouldWait, "Else should not need to call"); | |
2134 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
2135 // allow a potentially blocked foreground collector to proceed | |
2136 _c->_foregroundGCShouldWait = false; | |
2137 if (_c->_foregroundGCIsActive) { | |
2138 CGC_lock->notify(); | |
2139 } | |
2140 assert(!ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
2141 "Possible deadlock"); | |
2142 } | |
2143 | |
2144 ~ReleaseForegroundGC() { | |
2145 assert(!_c->_foregroundGCShouldWait, "Usage protocol violation?"); | |
2146 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
2147 _c->_foregroundGCShouldWait = true; | |
2148 } | |
2149 }; | |
2150 | |
2151 // There are separate collect_in_background and collect_in_foreground because of | |
2152 // the different locking requirements of the background collector and the | |
2153 // foreground collector. There was originally an attempt to share | |
2154 // one "collect" method between the background collector and the foreground | |
2155 // collector but the if-then-else required made it cleaner to have | |
2156 // separate methods. | |
2157 void CMSCollector::collect_in_background(bool clear_all_soft_refs) { | |
2158 assert(Thread::current()->is_ConcurrentGC_thread(), | |
2159 "A CMS asynchronous collection is only allowed on a CMS thread."); | |
2160 | |
2161 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
2162 { | |
2163 bool safepoint_check = Mutex::_no_safepoint_check_flag; | |
2164 MutexLockerEx hl(Heap_lock, safepoint_check); | |
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2165 FreelistLocker fll(this); |
0 | 2166 MutexLockerEx x(CGC_lock, safepoint_check); |
2167 if (_foregroundGCIsActive || !UseAsyncConcMarkSweepGC) { | |
2168 // The foreground collector is active or we're | |
2169 // not using asynchronous collections. Skip this | |
2170 // background collection. | |
2171 assert(!_foregroundGCShouldWait, "Should be clear"); | |
2172 return; | |
2173 } else { | |
2174 assert(_collectorState == Idling, "Should be idling before start."); | |
2175 _collectorState = InitialMarking; | |
2176 // Reset the expansion cause, now that we are about to begin | |
2177 // a new cycle. | |
2178 clear_expansion_cause(); | |
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2179 |
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2180 // Clear the MetaspaceGC flag since a concurrent collection |
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2181 // is starting but also clear it after the collection. |
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2182 MetaspaceGC::set_should_concurrent_collect(false); |
0 | 2183 } |
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2184 // Decide if we want to enable class unloading as part of the |
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2185 // ensuing concurrent GC cycle. |
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2186 update_should_unload_classes(); |
0 | 2187 _full_gc_requested = false; // acks all outstanding full gc requests |
2188 // Signal that we are about to start a collection | |
2189 gch->increment_total_full_collections(); // ... starting a collection cycle | |
2190 _collection_count_start = gch->total_full_collections(); | |
2191 } | |
2192 | |
2193 // Used for PrintGC | |
2194 size_t prev_used; | |
2195 if (PrintGC && Verbose) { | |
2196 prev_used = _cmsGen->used(); // XXXPERM | |
2197 } | |
2198 | |
2199 // The change of the collection state is normally done at this level; | |
2200 // the exceptions are phases that are executed while the world is | |
2201 // stopped. For those phases the change of state is done while the | |
2202 // world is stopped. For baton passing purposes this allows the | |
2203 // background collector to finish the phase and change state atomically. | |
2204 // The foreground collector cannot wait on a phase that is done | |
2205 // while the world is stopped because the foreground collector already | |
2206 // has the world stopped and would deadlock. | |
2207 while (_collectorState != Idling) { | |
2208 if (TraceCMSState) { | |
2209 gclog_or_tty->print_cr("Thread " INTPTR_FORMAT " in CMS state %d", | |
2210 Thread::current(), _collectorState); | |
2211 } | |
2212 // The foreground collector | |
2213 // holds the Heap_lock throughout its collection. | |
2214 // holds the CMS token (but not the lock) | |
2215 // except while it is waiting for the background collector to yield. | |
2216 // | |
2217 // The foreground collector should be blocked (not for long) | |
2218 // if the background collector is about to start a phase | |
2219 // executed with world stopped. If the background | |
2220 // collector has already started such a phase, the | |
2221 // foreground collector is blocked waiting for the | |
2222 // Heap_lock. The stop-world phases (InitialMarking and FinalMarking) | |
2223 // are executed in the VM thread. | |
2224 // | |
2225 // The locking order is | |
2226 // PendingListLock (PLL) -- if applicable (FinalMarking) | |
2227 // Heap_lock (both this & PLL locked in VM_CMS_Operation::prologue()) | |
2228 // CMS token (claimed in | |
2229 // stop_world_and_do() --> | |
2230 // safepoint_synchronize() --> | |
2231 // CMSThread::synchronize()) | |
2232 | |
2233 { | |
2234 // Check if the FG collector wants us to yield. | |
2235 CMSTokenSync x(true); // is cms thread | |
2236 if (waitForForegroundGC()) { | |
2237 // We yielded to a foreground GC, nothing more to be | |
2238 // done this round. | |
2239 assert(_foregroundGCShouldWait == false, "We set it to false in " | |
2240 "waitForForegroundGC()"); | |
2241 if (TraceCMSState) { | |
2242 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT | |
2243 " exiting collection CMS state %d", | |
2244 Thread::current(), _collectorState); | |
2245 } | |
2246 return; | |
2247 } else { | |
2248 // The background collector can run but check to see if the | |
2249 // foreground collector has done a collection while the | |
2250 // background collector was waiting to get the CGC_lock | |
2251 // above. If yes, break so that _foregroundGCShouldWait | |
2252 // is cleared before returning. | |
2253 if (_collectorState == Idling) { | |
2254 break; | |
2255 } | |
2256 } | |
2257 } | |
2258 | |
2259 assert(_foregroundGCShouldWait, "Foreground collector, if active, " | |
2260 "should be waiting"); | |
2261 | |
2262 switch (_collectorState) { | |
2263 case InitialMarking: | |
2264 { | |
2265 ReleaseForegroundGC x(this); | |
2266 stats().record_cms_begin(); | |
2267 | |
2268 VM_CMS_Initial_Mark initial_mark_op(this); | |
2269 VMThread::execute(&initial_mark_op); | |
2270 } | |
2271 // The collector state may be any legal state at this point | |
2272 // since the background collector may have yielded to the | |
2273 // foreground collector. | |
2274 break; | |
2275 case Marking: | |
2276 // initial marking in checkpointRootsInitialWork has been completed | |
2277 if (markFromRoots(true)) { // we were successful | |
2278 assert(_collectorState == Precleaning, "Collector state should " | |
2279 "have changed"); | |
2280 } else { | |
2281 assert(_foregroundGCIsActive, "Internal state inconsistency"); | |
2282 } | |
2283 break; | |
2284 case Precleaning: | |
2285 if (UseAdaptiveSizePolicy) { | |
2286 size_policy()->concurrent_precleaning_begin(); | |
2287 } | |
2288 // marking from roots in markFromRoots has been completed | |
2289 preclean(); | |
2290 if (UseAdaptiveSizePolicy) { | |
2291 size_policy()->concurrent_precleaning_end(); | |
2292 } | |
2293 assert(_collectorState == AbortablePreclean || | |
2294 _collectorState == FinalMarking, | |
2295 "Collector state should have changed"); | |
2296 break; | |
2297 case AbortablePreclean: | |
2298 if (UseAdaptiveSizePolicy) { | |
2299 size_policy()->concurrent_phases_resume(); | |
2300 } | |
2301 abortable_preclean(); | |
2302 if (UseAdaptiveSizePolicy) { | |
2303 size_policy()->concurrent_precleaning_end(); | |
2304 } | |
2305 assert(_collectorState == FinalMarking, "Collector state should " | |
2306 "have changed"); | |
2307 break; | |
2308 case FinalMarking: | |
2309 { | |
2310 ReleaseForegroundGC x(this); | |
2311 | |
2312 VM_CMS_Final_Remark final_remark_op(this); | |
2313 VMThread::execute(&final_remark_op); | |
935 | 2314 } |
0 | 2315 assert(_foregroundGCShouldWait, "block post-condition"); |
2316 break; | |
2317 case Sweeping: | |
2318 if (UseAdaptiveSizePolicy) { | |
2319 size_policy()->concurrent_sweeping_begin(); | |
2320 } | |
2321 // final marking in checkpointRootsFinal has been completed | |
2322 sweep(true); | |
2323 assert(_collectorState == Resizing, "Collector state change " | |
2324 "to Resizing must be done under the free_list_lock"); | |
2325 _full_gcs_since_conc_gc = 0; | |
2326 | |
2327 // Stop the timers for adaptive size policy for the concurrent phases | |
2328 if (UseAdaptiveSizePolicy) { | |
2329 size_policy()->concurrent_sweeping_end(); | |
2330 size_policy()->concurrent_phases_end(gch->gc_cause(), | |
2331 gch->prev_gen(_cmsGen)->capacity(), | |
2332 _cmsGen->free()); | |
2333 } | |
2334 | |
2335 case Resizing: { | |
2336 // Sweeping has been completed... | |
2337 // At this point the background collection has completed. | |
2338 // Don't move the call to compute_new_size() down | |
2339 // into code that might be executed if the background | |
2340 // collection was preempted. | |
2341 { | |
2342 ReleaseForegroundGC x(this); // unblock FG collection | |
2343 MutexLockerEx y(Heap_lock, Mutex::_no_safepoint_check_flag); | |
2344 CMSTokenSync z(true); // not strictly needed. | |
2345 if (_collectorState == Resizing) { | |
2346 compute_new_size(); | |
2347 _collectorState = Resetting; | |
2348 } else { | |
2349 assert(_collectorState == Idling, "The state should only change" | |
2350 " because the foreground collector has finished the collection"); | |
2351 } | |
2352 } | |
2353 break; | |
2354 } | |
2355 case Resetting: | |
2356 // CMS heap resizing has been completed | |
2357 reset(true); | |
2358 assert(_collectorState == Idling, "Collector state should " | |
2359 "have changed"); | |
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2360 |
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2361 MetaspaceGC::set_should_concurrent_collect(false); |
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2362 |
0 | 2363 stats().record_cms_end(); |
2364 // Don't move the concurrent_phases_end() and compute_new_size() | |
2365 // calls to here because a preempted background collection | |
2366 // has it's state set to "Resetting". | |
2367 break; | |
2368 case Idling: | |
2369 default: | |
2370 ShouldNotReachHere(); | |
2371 break; | |
2372 } | |
2373 if (TraceCMSState) { | |
2374 gclog_or_tty->print_cr(" Thread " INTPTR_FORMAT " done - next CMS state %d", | |
2375 Thread::current(), _collectorState); | |
2376 } | |
2377 assert(_foregroundGCShouldWait, "block post-condition"); | |
2378 } | |
2379 | |
2380 // Should this be in gc_epilogue? | |
2381 collector_policy()->counters()->update_counters(); | |
2382 | |
2383 { | |
2384 // Clear _foregroundGCShouldWait and, in the event that the | |
2385 // foreground collector is waiting, notify it, before | |
2386 // returning. | |
2387 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
2388 _foregroundGCShouldWait = false; | |
2389 if (_foregroundGCIsActive) { | |
2390 CGC_lock->notify(); | |
2391 } | |
2392 assert(!ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
2393 "Possible deadlock"); | |
2394 } | |
2395 if (TraceCMSState) { | |
2396 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT | |
2397 " exiting collection CMS state %d", | |
2398 Thread::current(), _collectorState); | |
2399 } | |
2400 if (PrintGC && Verbose) { | |
2401 _cmsGen->print_heap_change(prev_used); | |
2402 } | |
2403 } | |
2404 | |
2405 void CMSCollector::collect_in_foreground(bool clear_all_soft_refs) { | |
2406 assert(_foregroundGCIsActive && !_foregroundGCShouldWait, | |
2407 "Foreground collector should be waiting, not executing"); | |
2408 assert(Thread::current()->is_VM_thread(), "A foreground collection" | |
2409 "may only be done by the VM Thread with the world stopped"); | |
2410 assert(ConcurrentMarkSweepThread::vm_thread_has_cms_token(), | |
2411 "VM thread should have CMS token"); | |
2412 | |
2413 NOT_PRODUCT(TraceTime t("CMS:MS (foreground) ", PrintGCDetails && Verbose, | |
2414 true, gclog_or_tty);) | |
2415 if (UseAdaptiveSizePolicy) { | |
2416 size_policy()->ms_collection_begin(); | |
2417 } | |
2418 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact); | |
2419 | |
2420 HandleMark hm; // Discard invalid handles created during verification | |
2421 | |
2422 if (VerifyBeforeGC && | |
2423 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
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2424 Universe::verify(); |
0 | 2425 } |
2426 | |
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2427 // Snapshot the soft reference policy to be used in this collection cycle. |
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2428 ref_processor()->setup_policy(clear_all_soft_refs); |
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|
2429 |
0 | 2430 bool init_mark_was_synchronous = false; // until proven otherwise |
2431 while (_collectorState != Idling) { | |
2432 if (TraceCMSState) { | |
2433 gclog_or_tty->print_cr("Thread " INTPTR_FORMAT " in CMS state %d", | |
2434 Thread::current(), _collectorState); | |
2435 } | |
2436 switch (_collectorState) { | |
2437 case InitialMarking: | |
2438 init_mark_was_synchronous = true; // fact to be exploited in re-mark | |
2439 checkpointRootsInitial(false); | |
2440 assert(_collectorState == Marking, "Collector state should have changed" | |
2441 " within checkpointRootsInitial()"); | |
2442 break; | |
2443 case Marking: | |
2444 // initial marking in checkpointRootsInitialWork has been completed | |
2445 if (VerifyDuringGC && | |
2446 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
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2447 Universe::verify("Verify before initial mark: "); |
0 | 2448 } |
2449 { | |
2450 bool res = markFromRoots(false); | |
2451 assert(res && _collectorState == FinalMarking, "Collector state should " | |
2452 "have changed"); | |
2453 break; | |
2454 } | |
2455 case FinalMarking: | |
2456 if (VerifyDuringGC && | |
2457 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
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2458 Universe::verify("Verify before re-mark: "); |
0 | 2459 } |
2460 checkpointRootsFinal(false, clear_all_soft_refs, | |
2461 init_mark_was_synchronous); | |
2462 assert(_collectorState == Sweeping, "Collector state should not " | |
2463 "have changed within checkpointRootsFinal()"); | |
2464 break; | |
2465 case Sweeping: | |
2466 // final marking in checkpointRootsFinal has been completed | |
2467 if (VerifyDuringGC && | |
2468 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
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2469 Universe::verify("Verify before sweep: "); |
0 | 2470 } |
2471 sweep(false); | |
2472 assert(_collectorState == Resizing, "Incorrect state"); | |
2473 break; | |
2474 case Resizing: { | |
2475 // Sweeping has been completed; the actual resize in this case | |
2476 // is done separately; nothing to be done in this state. | |
2477 _collectorState = Resetting; | |
2478 break; | |
2479 } | |
2480 case Resetting: | |
2481 // The heap has been resized. | |
2482 if (VerifyDuringGC && | |
2483 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
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2484 Universe::verify("Verify before reset: "); |
0 | 2485 } |
2486 reset(false); | |
2487 assert(_collectorState == Idling, "Collector state should " | |
2488 "have changed"); | |
2489 break; | |
2490 case Precleaning: | |
2491 case AbortablePreclean: | |
2492 // Elide the preclean phase | |
2493 _collectorState = FinalMarking; | |
2494 break; | |
2495 default: | |
2496 ShouldNotReachHere(); | |
2497 } | |
2498 if (TraceCMSState) { | |
2499 gclog_or_tty->print_cr(" Thread " INTPTR_FORMAT " done - next CMS state %d", | |
2500 Thread::current(), _collectorState); | |
2501 } | |
2502 } | |
2503 | |
2504 if (UseAdaptiveSizePolicy) { | |
2505 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
2506 size_policy()->ms_collection_end(gch->gc_cause()); | |
2507 } | |
2508 | |
2509 if (VerifyAfterGC && | |
2510 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
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2511 Universe::verify(); |
0 | 2512 } |
2513 if (TraceCMSState) { | |
2514 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT | |
2515 " exiting collection CMS state %d", | |
2516 Thread::current(), _collectorState); | |
2517 } | |
2518 } | |
2519 | |
2520 bool CMSCollector::waitForForegroundGC() { | |
2521 bool res = false; | |
2522 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
2523 "CMS thread should have CMS token"); | |
2524 // Block the foreground collector until the | |
2525 // background collectors decides whether to | |
2526 // yield. | |
2527 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
2528 _foregroundGCShouldWait = true; | |
2529 if (_foregroundGCIsActive) { | |
2530 // The background collector yields to the | |
2531 // foreground collector and returns a value | |
2532 // indicating that it has yielded. The foreground | |
2533 // collector can proceed. | |
2534 res = true; | |
2535 _foregroundGCShouldWait = false; | |
2536 ConcurrentMarkSweepThread::clear_CMS_flag( | |
2537 ConcurrentMarkSweepThread::CMS_cms_has_token); | |
2538 ConcurrentMarkSweepThread::set_CMS_flag( | |
2539 ConcurrentMarkSweepThread::CMS_cms_wants_token); | |
2540 // Get a possibly blocked foreground thread going | |
2541 CGC_lock->notify(); | |
2542 if (TraceCMSState) { | |
2543 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT " waiting at CMS state %d", | |
2544 Thread::current(), _collectorState); | |
2545 } | |
2546 while (_foregroundGCIsActive) { | |
2547 CGC_lock->wait(Mutex::_no_safepoint_check_flag); | |
2548 } | |
2549 ConcurrentMarkSweepThread::set_CMS_flag( | |
2550 ConcurrentMarkSweepThread::CMS_cms_has_token); | |
2551 ConcurrentMarkSweepThread::clear_CMS_flag( | |
2552 ConcurrentMarkSweepThread::CMS_cms_wants_token); | |
2553 } | |
2554 if (TraceCMSState) { | |
2555 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT " continuing at CMS state %d", | |
2556 Thread::current(), _collectorState); | |
2557 } | |
2558 return res; | |
2559 } | |
2560 | |
2561 // Because of the need to lock the free lists and other structures in | |
2562 // the collector, common to all the generations that the collector is | |
2563 // collecting, we need the gc_prologues of individual CMS generations | |
2564 // delegate to their collector. It may have been simpler had the | |
2565 // current infrastructure allowed one to call a prologue on a | |
2566 // collector. In the absence of that we have the generation's | |
2567 // prologue delegate to the collector, which delegates back | |
2568 // some "local" work to a worker method in the individual generations | |
2569 // that it's responsible for collecting, while itself doing any | |
2570 // work common to all generations it's responsible for. A similar | |
2571 // comment applies to the gc_epilogue()'s. | |
2572 // The role of the varaible _between_prologue_and_epilogue is to | |
2573 // enforce the invocation protocol. | |
2574 void CMSCollector::gc_prologue(bool full) { | |
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2575 // Call gc_prologue_work() for the CMSGen |
0 | 2576 // we are responsible for. |
2577 | |
2578 // The following locking discipline assumes that we are only called | |
2579 // when the world is stopped. | |
2580 assert(SafepointSynchronize::is_at_safepoint(), "world is stopped assumption"); | |
2581 | |
2582 // The CMSCollector prologue must call the gc_prologues for the | |
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2583 // "generations" that it's responsible |
0 | 2584 // for. |
2585 | |
2586 assert( Thread::current()->is_VM_thread() | |
2587 || ( CMSScavengeBeforeRemark | |
2588 && Thread::current()->is_ConcurrentGC_thread()), | |
2589 "Incorrect thread type for prologue execution"); | |
2590 | |
2591 if (_between_prologue_and_epilogue) { | |
2592 // We have already been invoked; this is a gc_prologue delegation | |
2593 // from yet another CMS generation that we are responsible for, just | |
2594 // ignore it since all relevant work has already been done. | |
2595 return; | |
2596 } | |
2597 | |
2598 // set a bit saying prologue has been called; cleared in epilogue | |
2599 _between_prologue_and_epilogue = true; | |
2600 // Claim locks for common data structures, then call gc_prologue_work() | |
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2601 // for each CMSGen. |
0 | 2602 |
2603 getFreelistLocks(); // gets free list locks on constituent spaces | |
2604 bitMapLock()->lock_without_safepoint_check(); | |
2605 | |
2606 // Should call gc_prologue_work() for all cms gens we are responsible for | |
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2607 bool duringMarking = _collectorState >= Marking |
0 | 2608 && _collectorState < Sweeping; |
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2609 |
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2610 // The young collections clear the modified oops state, which tells if |
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2611 // there are any modified oops in the class. The remark phase also needs |
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2612 // that information. Tell the young collection to save the union of all |
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2613 // modified klasses. |
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2614 if (duringMarking) { |
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2615 _ct->klass_rem_set()->set_accumulate_modified_oops(true); |
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2616 } |
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2617 |
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2618 bool registerClosure = duringMarking; |
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2619 |
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2620 ModUnionClosure* muc = CollectedHeap::use_parallel_gc_threads() ? |
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2621 &_modUnionClosurePar |
0 | 2622 : &_modUnionClosure; |
2623 _cmsGen->gc_prologue_work(full, registerClosure, muc); | |
2624 | |
2625 if (!full) { | |
2626 stats().record_gc0_begin(); | |
2627 } | |
2628 } | |
2629 | |
2630 void ConcurrentMarkSweepGeneration::gc_prologue(bool full) { | |
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2631 |
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2632 _capacity_at_prologue = capacity(); |
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2633 _used_at_prologue = used(); |
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2634 |
0 | 2635 // Delegate to CMScollector which knows how to coordinate between |
2636 // this and any other CMS generations that it is responsible for | |
2637 // collecting. | |
2638 collector()->gc_prologue(full); | |
2639 } | |
2640 | |
2641 // This is a "private" interface for use by this generation's CMSCollector. | |
2642 // Not to be called directly by any other entity (for instance, | |
2643 // GenCollectedHeap, which calls the "public" gc_prologue method above). | |
2644 void ConcurrentMarkSweepGeneration::gc_prologue_work(bool full, | |
2645 bool registerClosure, ModUnionClosure* modUnionClosure) { | |
2646 assert(!incremental_collection_failed(), "Shouldn't be set yet"); | |
2647 assert(cmsSpace()->preconsumptionDirtyCardClosure() == NULL, | |
2648 "Should be NULL"); | |
2649 if (registerClosure) { | |
2650 cmsSpace()->setPreconsumptionDirtyCardClosure(modUnionClosure); | |
2651 } | |
2652 cmsSpace()->gc_prologue(); | |
2653 // Clear stat counters | |
2654 NOT_PRODUCT( | |
2655 assert(_numObjectsPromoted == 0, "check"); | |
2656 assert(_numWordsPromoted == 0, "check"); | |
2657 if (Verbose && PrintGC) { | |
2658 gclog_or_tty->print("Allocated "SIZE_FORMAT" objects, " | |
2659 SIZE_FORMAT" bytes concurrently", | |
2660 _numObjectsAllocated, _numWordsAllocated*sizeof(HeapWord)); | |
2661 } | |
2662 _numObjectsAllocated = 0; | |
2663 _numWordsAllocated = 0; | |
2664 ) | |
2665 } | |
2666 | |
2667 void CMSCollector::gc_epilogue(bool full) { | |
2668 // The following locking discipline assumes that we are only called | |
2669 // when the world is stopped. | |
2670 assert(SafepointSynchronize::is_at_safepoint(), | |
2671 "world is stopped assumption"); | |
2672 | |
2673 // Currently the CMS epilogue (see CompactibleFreeListSpace) merely checks | |
2674 // if linear allocation blocks need to be appropriately marked to allow the | |
2675 // the blocks to be parsable. We also check here whether we need to nudge the | |
2676 // CMS collector thread to start a new cycle (if it's not already active). | |
2677 assert( Thread::current()->is_VM_thread() | |
2678 || ( CMSScavengeBeforeRemark | |
2679 && Thread::current()->is_ConcurrentGC_thread()), | |
2680 "Incorrect thread type for epilogue execution"); | |
2681 | |
2682 if (!_between_prologue_and_epilogue) { | |
2683 // We have already been invoked; this is a gc_epilogue delegation | |
2684 // from yet another CMS generation that we are responsible for, just | |
2685 // ignore it since all relevant work has already been done. | |
2686 return; | |
2687 } | |
2688 assert(haveFreelistLocks(), "must have freelist locks"); | |
2689 assert_lock_strong(bitMapLock()); | |
2690 | |
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2691 _ct->klass_rem_set()->set_accumulate_modified_oops(false); |
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2692 |
0 | 2693 _cmsGen->gc_epilogue_work(full); |
2694 | |
2695 if (_collectorState == AbortablePreclean || _collectorState == Precleaning) { | |
2696 // in case sampling was not already enabled, enable it | |
2697 _start_sampling = true; | |
2698 } | |
2699 // reset _eden_chunk_array so sampling starts afresh | |
2700 _eden_chunk_index = 0; | |
2701 | |
2702 size_t cms_used = _cmsGen->cmsSpace()->used(); | |
2703 | |
2704 // update performance counters - this uses a special version of | |
2705 // update_counters() that allows the utilization to be passed as a | |
2706 // parameter, avoiding multiple calls to used(). | |
2707 // | |
2708 _cmsGen->update_counters(cms_used); | |
2709 | |
2710 if (CMSIncrementalMode) { | |
2711 icms_update_allocation_limits(); | |
2712 } | |
2713 | |
2714 bitMapLock()->unlock(); | |
2715 releaseFreelistLocks(); | |
2716 | |
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2717 if (!CleanChunkPoolAsync) { |
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2718 Chunk::clean_chunk_pool(); |
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2719 } |
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2720 |
0 | 2721 _between_prologue_and_epilogue = false; // ready for next cycle |
2722 } | |
2723 | |
2724 void ConcurrentMarkSweepGeneration::gc_epilogue(bool full) { | |
2725 collector()->gc_epilogue(full); | |
2726 | |
2727 // Also reset promotion tracking in par gc thread states. | |
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2728 if (CollectedHeap::use_parallel_gc_threads()) { |
0 | 2729 for (uint i = 0; i < ParallelGCThreads; i++) { |
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2730 _par_gc_thread_states[i]->promo.stopTrackingPromotions(i); |
0 | 2731 } |
2732 } | |
2733 } | |
2734 | |
2735 void ConcurrentMarkSweepGeneration::gc_epilogue_work(bool full) { | |
2736 assert(!incremental_collection_failed(), "Should have been cleared"); | |
2737 cmsSpace()->setPreconsumptionDirtyCardClosure(NULL); | |
2738 cmsSpace()->gc_epilogue(); | |
2739 // Print stat counters | |
2740 NOT_PRODUCT( | |
2741 assert(_numObjectsAllocated == 0, "check"); | |
2742 assert(_numWordsAllocated == 0, "check"); | |
2743 if (Verbose && PrintGC) { | |
2744 gclog_or_tty->print("Promoted "SIZE_FORMAT" objects, " | |
2745 SIZE_FORMAT" bytes", | |
2746 _numObjectsPromoted, _numWordsPromoted*sizeof(HeapWord)); | |
2747 } | |
2748 _numObjectsPromoted = 0; | |
2749 _numWordsPromoted = 0; | |
2750 ) | |
2751 | |
2752 if (PrintGC && Verbose) { | |
2753 // Call down the chain in contiguous_available needs the freelistLock | |
2754 // so print this out before releasing the freeListLock. | |
2755 gclog_or_tty->print(" Contiguous available "SIZE_FORMAT" bytes ", | |
2756 contiguous_available()); | |
2757 } | |
2758 } | |
2759 | |
2760 #ifndef PRODUCT | |
2761 bool CMSCollector::have_cms_token() { | |
2762 Thread* thr = Thread::current(); | |
2763 if (thr->is_VM_thread()) { | |
2764 return ConcurrentMarkSweepThread::vm_thread_has_cms_token(); | |
2765 } else if (thr->is_ConcurrentGC_thread()) { | |
2766 return ConcurrentMarkSweepThread::cms_thread_has_cms_token(); | |
2767 } else if (thr->is_GC_task_thread()) { | |
2768 return ConcurrentMarkSweepThread::vm_thread_has_cms_token() && | |
2769 ParGCRareEvent_lock->owned_by_self(); | |
2770 } | |
2771 return false; | |
2772 } | |
2773 #endif | |
2774 | |
2775 // Check reachability of the given heap address in CMS generation, | |
2776 // treating all other generations as roots. | |
2777 bool CMSCollector::is_cms_reachable(HeapWord* addr) { | |
2778 // We could "guarantee" below, rather than assert, but i'll | |
2779 // leave these as "asserts" so that an adventurous debugger | |
2780 // could try this in the product build provided some subset of | |
2781 // the conditions were met, provided they were intersted in the | |
2782 // results and knew that the computation below wouldn't interfere | |
2783 // with other concurrent computations mutating the structures | |
2784 // being read or written. | |
2785 assert(SafepointSynchronize::is_at_safepoint(), | |
2786 "Else mutations in object graph will make answer suspect"); | |
2787 assert(have_cms_token(), "Should hold cms token"); | |
2788 assert(haveFreelistLocks(), "must hold free list locks"); | |
2789 assert_lock_strong(bitMapLock()); | |
2790 | |
2791 // Clear the marking bit map array before starting, but, just | |
2792 // for kicks, first report if the given address is already marked | |
2793 gclog_or_tty->print_cr("Start: Address 0x%x is%s marked", addr, | |
2794 _markBitMap.isMarked(addr) ? "" : " not"); | |
2795 | |
2796 if (verify_after_remark()) { | |
2797 MutexLockerEx x(verification_mark_bm()->lock(), Mutex::_no_safepoint_check_flag); | |
2798 bool result = verification_mark_bm()->isMarked(addr); | |
2799 gclog_or_tty->print_cr("TransitiveMark: Address 0x%x %s marked", addr, | |
2800 result ? "IS" : "is NOT"); | |
2801 return result; | |
2802 } else { | |
2803 gclog_or_tty->print_cr("Could not compute result"); | |
2804 return false; | |
2805 } | |
2806 } | |
2807 | |
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2808 |
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2809 void |
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2810 CMSCollector::print_on_error(outputStream* st) { |
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2811 CMSCollector* collector = ConcurrentMarkSweepGeneration::_collector; |
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2812 if (collector != NULL) { |
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2813 CMSBitMap* bitmap = &collector->_markBitMap; |
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2814 st->print_cr("Marking Bits: (CMSBitMap*) " PTR_FORMAT, bitmap); |
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2815 bitmap->print_on_error(st, " Bits: "); |
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2816 |
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2817 st->cr(); |
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2818 |
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2819 CMSBitMap* mut_bitmap = &collector->_modUnionTable; |
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2820 st->print_cr("Mod Union Table: (CMSBitMap*) " PTR_FORMAT, mut_bitmap); |
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2821 mut_bitmap->print_on_error(st, " Bits: "); |
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2822 } |
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2823 } |
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2824 |
0 | 2825 //////////////////////////////////////////////////////// |
2826 // CMS Verification Support | |
2827 //////////////////////////////////////////////////////// | |
2828 // Following the remark phase, the following invariant | |
2829 // should hold -- each object in the CMS heap which is | |
2830 // marked in markBitMap() should be marked in the verification_mark_bm(). | |
2831 | |
2832 class VerifyMarkedClosure: public BitMapClosure { | |
2833 CMSBitMap* _marks; | |
2834 bool _failed; | |
2835 | |
2836 public: | |
2837 VerifyMarkedClosure(CMSBitMap* bm): _marks(bm), _failed(false) {} | |
2838 | |
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2839 bool do_bit(size_t offset) { |
0 | 2840 HeapWord* addr = _marks->offsetToHeapWord(offset); |
2841 if (!_marks->isMarked(addr)) { | |
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2842 oop(addr)->print_on(gclog_or_tty); |
0 | 2843 gclog_or_tty->print_cr(" ("INTPTR_FORMAT" should have been marked)", addr); |
2844 _failed = true; | |
2845 } | |
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2846 return true; |
0 | 2847 } |
2848 | |
2849 bool failed() { return _failed; } | |
2850 }; | |
2851 | |
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2852 bool CMSCollector::verify_after_remark(bool silent) { |
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2853 if (!silent) gclog_or_tty->print(" [Verifying CMS Marking... "); |
0 | 2854 MutexLockerEx ml(verification_mark_bm()->lock(), Mutex::_no_safepoint_check_flag); |
2855 static bool init = false; | |
2856 | |
2857 assert(SafepointSynchronize::is_at_safepoint(), | |
2858 "Else mutations in object graph will make answer suspect"); | |
2859 assert(have_cms_token(), | |
2860 "Else there may be mutual interference in use of " | |
2861 " verification data structures"); | |
2862 assert(_collectorState > Marking && _collectorState <= Sweeping, | |
2863 "Else marking info checked here may be obsolete"); | |
2864 assert(haveFreelistLocks(), "must hold free list locks"); | |
2865 assert_lock_strong(bitMapLock()); | |
2866 | |
2867 | |
2868 // Allocate marking bit map if not already allocated | |
2869 if (!init) { // first time | |
2870 if (!verification_mark_bm()->allocate(_span)) { | |
2871 return false; | |
2872 } | |
2873 init = true; | |
2874 } | |
2875 | |
2876 assert(verification_mark_stack()->isEmpty(), "Should be empty"); | |
2877 | |
2878 // Turn off refs discovery -- so we will be tracing through refs. | |
2879 // This is as intended, because by this time | |
2880 // GC must already have cleared any refs that need to be cleared, | |
2881 // and traced those that need to be marked; moreover, | |
2882 // the marking done here is not going to intefere in any | |
2883 // way with the marking information used by GC. | |
2884 NoRefDiscovery no_discovery(ref_processor()); | |
2885 | |
2886 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact;) | |
2887 | |
2888 // Clear any marks from a previous round | |
2889 verification_mark_bm()->clear_all(); | |
2890 assert(verification_mark_stack()->isEmpty(), "markStack should be empty"); | |
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2891 verify_work_stacks_empty(); |
0 | 2892 |
2893 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
2894 gch->ensure_parsability(false); // fill TLABs, but no need to retire them | |
2895 // Update the saved marks which may affect the root scans. | |
2896 gch->save_marks(); | |
2897 | |
2898 if (CMSRemarkVerifyVariant == 1) { | |
2899 // In this first variant of verification, we complete | |
2900 // all marking, then check if the new marks-verctor is | |
2901 // a subset of the CMS marks-vector. | |
2902 verify_after_remark_work_1(); | |
2903 } else if (CMSRemarkVerifyVariant == 2) { | |
2904 // In this second variant of verification, we flag an error | |
2905 // (i.e. an object reachable in the new marks-vector not reachable | |
2906 // in the CMS marks-vector) immediately, also indicating the | |
2907 // identify of an object (A) that references the unmarked object (B) -- | |
2908 // presumably, a mutation to A failed to be picked up by preclean/remark? | |
2909 verify_after_remark_work_2(); | |
2910 } else { | |
2911 warning("Unrecognized value %d for CMSRemarkVerifyVariant", | |
2912 CMSRemarkVerifyVariant); | |
2913 } | |
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2914 if (!silent) gclog_or_tty->print(" done] "); |
0 | 2915 return true; |
2916 } | |
2917 | |
2918 void CMSCollector::verify_after_remark_work_1() { | |
2919 ResourceMark rm; | |
2920 HandleMark hm; | |
2921 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
2922 | |
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2923 // Get a clear set of claim bits for the strong roots processing to work with. |
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2924 ClassLoaderDataGraph::clear_claimed_marks(); |
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2925 |
0 | 2926 // Mark from roots one level into CMS |
994
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2927 MarkRefsIntoClosure notOlder(_span, verification_mark_bm()); |
0 | 2928 gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel. |
2929 | |
2930 gch->gen_process_strong_roots(_cmsGen->level(), | |
2931 true, // younger gens are roots | |
989
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2932 true, // activate StrongRootsScope |
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2933 false, // not scavenging |
0 | 2934 SharedHeap::ScanningOption(roots_scanning_options()), |
989
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2935 ¬Older, |
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2936 true, // walk code active on stacks |
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2937 NULL, |
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2938 NULL); // SSS: Provide correct closure |
0 | 2939 |
2940 // Now mark from the roots | |
2941 MarkFromRootsClosure markFromRootsClosure(this, _span, | |
6725
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2942 verification_mark_bm(), verification_mark_stack(), |
0 | 2943 false /* don't yield */, true /* verifying */); |
2944 assert(_restart_addr == NULL, "Expected pre-condition"); | |
2945 verification_mark_bm()->iterate(&markFromRootsClosure); | |
2946 while (_restart_addr != NULL) { | |
2947 // Deal with stack overflow: by restarting at the indicated | |
2948 // address. | |
2949 HeapWord* ra = _restart_addr; | |
2950 markFromRootsClosure.reset(ra); | |
2951 _restart_addr = NULL; | |
2952 verification_mark_bm()->iterate(&markFromRootsClosure, ra, _span.end()); | |
2953 } | |
2954 assert(verification_mark_stack()->isEmpty(), "Should have been drained"); | |
2955 verify_work_stacks_empty(); | |
2956 | |
2957 // Marking completed -- now verify that each bit marked in | |
2958 // verification_mark_bm() is also marked in markBitMap(); flag all | |
2959 // errors by printing corresponding objects. | |
2960 VerifyMarkedClosure vcl(markBitMap()); | |
2961 verification_mark_bm()->iterate(&vcl); | |
2962 if (vcl.failed()) { | |
2963 gclog_or_tty->print("Verification failed"); | |
1145
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2964 Universe::heap()->print_on(gclog_or_tty); |
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2965 fatal("CMS: failed marking verification after remark"); |
0 | 2966 } |
2967 } | |
2968 | |
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2969 class VerifyKlassOopsKlassClosure : public KlassClosure { |
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2970 class VerifyKlassOopsClosure : public OopClosure { |
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2971 CMSBitMap* _bitmap; |
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2972 public: |
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2973 VerifyKlassOopsClosure(CMSBitMap* bitmap) : _bitmap(bitmap) { } |
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2974 void do_oop(oop* p) { guarantee(*p == NULL || _bitmap->isMarked((HeapWord*) *p), "Should be marked"); } |
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2975 void do_oop(narrowOop* p) { ShouldNotReachHere(); } |
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2976 } _oop_closure; |
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2977 public: |
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2978 VerifyKlassOopsKlassClosure(CMSBitMap* bitmap) : _oop_closure(bitmap) {} |
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2979 void do_klass(Klass* k) { |
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2980 k->oops_do(&_oop_closure); |
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2981 } |
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2982 }; |
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2983 |
0 | 2984 void CMSCollector::verify_after_remark_work_2() { |
2985 ResourceMark rm; | |
2986 HandleMark hm; | |
2987 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
2988 | |
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2989 // Get a clear set of claim bits for the strong roots processing to work with. |
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2990 ClassLoaderDataGraph::clear_claimed_marks(); |
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2991 |
0 | 2992 // Mark from roots one level into CMS |
2993 MarkRefsIntoVerifyClosure notOlder(_span, verification_mark_bm(), | |
994
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2994 markBitMap()); |
6725
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2995 CMKlassClosure klass_closure(¬Older); |
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2996 |
0 | 2997 gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel. |
2998 gch->gen_process_strong_roots(_cmsGen->level(), | |
2999 true, // younger gens are roots | |
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3000 true, // activate StrongRootsScope |
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3001 false, // not scavenging |
0 | 3002 SharedHeap::ScanningOption(roots_scanning_options()), |
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3003 ¬Older, |
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3004 true, // walk code active on stacks |
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3005 NULL, |
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3006 &klass_closure); |
0 | 3007 |
3008 // Now mark from the roots | |
3009 MarkFromRootsVerifyClosure markFromRootsClosure(this, _span, | |
3010 verification_mark_bm(), markBitMap(), verification_mark_stack()); | |
3011 assert(_restart_addr == NULL, "Expected pre-condition"); | |
3012 verification_mark_bm()->iterate(&markFromRootsClosure); | |
3013 while (_restart_addr != NULL) { | |
3014 // Deal with stack overflow: by restarting at the indicated | |
3015 // address. | |
3016 HeapWord* ra = _restart_addr; | |
3017 markFromRootsClosure.reset(ra); | |
3018 _restart_addr = NULL; | |
3019 verification_mark_bm()->iterate(&markFromRootsClosure, ra, _span.end()); | |
3020 } | |
3021 assert(verification_mark_stack()->isEmpty(), "Should have been drained"); | |
3022 verify_work_stacks_empty(); | |
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3023 |
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3024 VerifyKlassOopsKlassClosure verify_klass_oops(verification_mark_bm()); |
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3025 ClassLoaderDataGraph::classes_do(&verify_klass_oops); |
0 | 3026 |
3027 // Marking completed -- now verify that each bit marked in | |
3028 // verification_mark_bm() is also marked in markBitMap(); flag all | |
3029 // errors by printing corresponding objects. | |
3030 VerifyMarkedClosure vcl(markBitMap()); | |
3031 verification_mark_bm()->iterate(&vcl); | |
3032 assert(!vcl.failed(), "Else verification above should not have succeeded"); | |
3033 } | |
3034 | |
3035 void ConcurrentMarkSweepGeneration::save_marks() { | |
3036 // delegate to CMS space | |
3037 cmsSpace()->save_marks(); | |
3038 for (uint i = 0; i < ParallelGCThreads; i++) { | |
3039 _par_gc_thread_states[i]->promo.startTrackingPromotions(); | |
3040 } | |
3041 } | |
3042 | |
3043 bool ConcurrentMarkSweepGeneration::no_allocs_since_save_marks() { | |
3044 return cmsSpace()->no_allocs_since_save_marks(); | |
3045 } | |
3046 | |
3047 #define CMS_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \ | |
3048 \ | |
3049 void ConcurrentMarkSweepGeneration:: \ | |
3050 oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) { \ | |
3051 cl->set_generation(this); \ | |
3052 cmsSpace()->oop_since_save_marks_iterate##nv_suffix(cl); \ | |
3053 cl->reset_generation(); \ | |
3054 save_marks(); \ | |
3055 } | |
3056 | |
3057 ALL_SINCE_SAVE_MARKS_CLOSURES(CMS_SINCE_SAVE_MARKS_DEFN) | |
3058 | |
3059 void | |
3060 ConcurrentMarkSweepGeneration::object_iterate_since_last_GC(ObjectClosure* blk) | |
3061 { | |
3062 // Not currently implemented; need to do the following. -- ysr. | |
3063 // dld -- I think that is used for some sort of allocation profiler. So it | |
3064 // really means the objects allocated by the mutator since the last | |
3065 // GC. We could potentially implement this cheaply by recording only | |
3066 // the direct allocations in a side data structure. | |
3067 // | |
3068 // I think we probably ought not to be required to support these | |
3069 // iterations at any arbitrary point; I think there ought to be some | |
3070 // call to enable/disable allocation profiling in a generation/space, | |
3071 // and the iterator ought to return the objects allocated in the | |
3072 // gen/space since the enable call, or the last iterator call (which | |
3073 // will probably be at a GC.) That way, for gens like CM&S that would | |
3074 // require some extra data structure to support this, we only pay the | |
3075 // cost when it's in use... | |
3076 cmsSpace()->object_iterate_since_last_GC(blk); | |
3077 } | |
3078 | |
3079 void | |
3080 ConcurrentMarkSweepGeneration::younger_refs_iterate(OopsInGenClosure* cl) { | |
3081 cl->set_generation(this); | |
3082 younger_refs_in_space_iterate(_cmsSpace, cl); | |
3083 cl->reset_generation(); | |
3084 } | |
3085 | |
3086 void | |
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3087 ConcurrentMarkSweepGeneration::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) { |
0 | 3088 if (freelistLock()->owned_by_self()) { |
3089 Generation::oop_iterate(mr, cl); | |
3090 } else { | |
3091 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
3092 Generation::oop_iterate(mr, cl); | |
3093 } | |
3094 } | |
3095 | |
3096 void | |
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3097 ConcurrentMarkSweepGeneration::oop_iterate(ExtendedOopClosure* cl) { |
0 | 3098 if (freelistLock()->owned_by_self()) { |
3099 Generation::oop_iterate(cl); | |
3100 } else { | |
3101 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
3102 Generation::oop_iterate(cl); | |
3103 } | |
3104 } | |
3105 | |
3106 void | |
3107 ConcurrentMarkSweepGeneration::object_iterate(ObjectClosure* cl) { | |
3108 if (freelistLock()->owned_by_self()) { | |
3109 Generation::object_iterate(cl); | |
3110 } else { | |
3111 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
3112 Generation::object_iterate(cl); | |
3113 } | |
3114 } | |
3115 | |
3116 void | |
517
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3117 ConcurrentMarkSweepGeneration::safe_object_iterate(ObjectClosure* cl) { |
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3118 if (freelistLock()->owned_by_self()) { |
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3119 Generation::safe_object_iterate(cl); |
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3120 } else { |
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3121 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); |
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3122 Generation::safe_object_iterate(cl); |
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3123 } |
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3124 } |
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3125 |
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3126 void |
0 | 3127 ConcurrentMarkSweepGeneration::post_compact() { |
3128 } | |
3129 | |
3130 void | |
3131 ConcurrentMarkSweepGeneration::prepare_for_verify() { | |
3132 // Fix the linear allocation blocks to look like free blocks. | |
3133 | |
3134 // Locks are normally acquired/released in gc_prologue/gc_epilogue, but those | |
3135 // are not called when the heap is verified during universe initialization and | |
3136 // at vm shutdown. | |
3137 if (freelistLock()->owned_by_self()) { | |
3138 cmsSpace()->prepare_for_verify(); | |
3139 } else { | |
3140 MutexLockerEx fll(freelistLock(), Mutex::_no_safepoint_check_flag); | |
3141 cmsSpace()->prepare_for_verify(); | |
3142 } | |
3143 } | |
3144 | |
3145 void | |
6008 | 3146 ConcurrentMarkSweepGeneration::verify() { |
0 | 3147 // Locks are normally acquired/released in gc_prologue/gc_epilogue, but those |
3148 // are not called when the heap is verified during universe initialization and | |
3149 // at vm shutdown. | |
3150 if (freelistLock()->owned_by_self()) { | |
6008 | 3151 cmsSpace()->verify(); |
0 | 3152 } else { |
3153 MutexLockerEx fll(freelistLock(), Mutex::_no_safepoint_check_flag); | |
6008 | 3154 cmsSpace()->verify(); |
3155 } | |
3156 } | |
3157 | |
3158 void CMSCollector::verify() { | |
3159 _cmsGen->verify(); | |
0 | 3160 } |
3161 | |
3162 #ifndef PRODUCT | |
3163 bool CMSCollector::overflow_list_is_empty() const { | |
3164 assert(_num_par_pushes >= 0, "Inconsistency"); | |
3165 if (_overflow_list == NULL) { | |
3166 assert(_num_par_pushes == 0, "Inconsistency"); | |
3167 } | |
3168 return _overflow_list == NULL; | |
3169 } | |
3170 | |
3171 // The methods verify_work_stacks_empty() and verify_overflow_empty() | |
3172 // merely consolidate assertion checks that appear to occur together frequently. | |
3173 void CMSCollector::verify_work_stacks_empty() const { | |
3174 assert(_markStack.isEmpty(), "Marking stack should be empty"); | |
3175 assert(overflow_list_is_empty(), "Overflow list should be empty"); | |
3176 } | |
3177 | |
3178 void CMSCollector::verify_overflow_empty() const { | |
3179 assert(overflow_list_is_empty(), "Overflow list should be empty"); | |
3180 assert(no_preserved_marks(), "No preserved marks"); | |
3181 } | |
3182 #endif // PRODUCT | |
3183 | |
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3184 // Decide if we want to enable class unloading as part of the |
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3185 // ensuing concurrent GC cycle. We will collect and |
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3186 // unload classes if it's the case that: |
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3187 // (1) an explicit gc request has been made and the flag |
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3188 // ExplicitGCInvokesConcurrentAndUnloadsClasses is set, OR |
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3189 // (2) (a) class unloading is enabled at the command line, and |
6725
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3190 // (b) old gen is getting really full |
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3191 // NOTE: Provided there is no change in the state of the heap between |
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3192 // calls to this method, it should have idempotent results. Moreover, |
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3193 // its results should be monotonically increasing (i.e. going from 0 to 1, |
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3194 // but not 1 to 0) between successive calls between which the heap was |
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3195 // not collected. For the implementation below, it must thus rely on |
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3196 // the property that concurrent_cycles_since_last_unload() |
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3197 // will not decrease unless a collection cycle happened and that |
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3198 // _cmsGen->is_too_full() are |
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3199 // themselves also monotonic in that sense. See check_monotonicity() |
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3200 // below. |
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3201 void CMSCollector::update_should_unload_classes() { |
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3202 _should_unload_classes = false; |
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3203 // Condition 1 above |
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3204 if (_full_gc_requested && ExplicitGCInvokesConcurrentAndUnloadsClasses) { |
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3205 _should_unload_classes = true; |
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3206 } else if (CMSClassUnloadingEnabled) { // Condition 2.a above |
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3207 // Disjuncts 2.b.(i,ii,iii) above |
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3208 _should_unload_classes = (concurrent_cycles_since_last_unload() >= |
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3209 CMSClassUnloadingMaxInterval) |
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3210 || _cmsGen->is_too_full(); |
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3211 } |
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3212 } |
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3213 |
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3214 bool ConcurrentMarkSweepGeneration::is_too_full() const { |
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3215 bool res = should_concurrent_collect(); |
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3216 res = res && (occupancy() > (double)CMSIsTooFullPercentage/100.0); |
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3217 return res; |
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3218 } |
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3219 |
0 | 3220 void CMSCollector::setup_cms_unloading_and_verification_state() { |
3293
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3221 const bool should_verify = VerifyBeforeGC || VerifyAfterGC || VerifyDuringGC |
0 | 3222 || VerifyBeforeExit; |
3293
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3223 const int rso = SharedHeap::SO_Strings | SharedHeap::SO_CodeCache; |
0 | 3224 |
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3225 if (should_unload_classes()) { // Should unload classes this cycle |
0 | 3226 remove_root_scanning_option(rso); // Shrink the root set appropriately |
3227 set_verifying(should_verify); // Set verification state for this cycle | |
3228 return; // Nothing else needs to be done at this time | |
3229 } | |
3230 | |
3231 // Not unloading classes this cycle | |
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3232 assert(!should_unload_classes(), "Inconsitency!"); |
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3233 if ((!verifying() || unloaded_classes_last_cycle()) && should_verify) { |
0 | 3234 // Include symbols, strings and code cache elements to prevent their resurrection. |
3235 add_root_scanning_option(rso); | |
3236 set_verifying(true); | |
3237 } else if (verifying() && !should_verify) { | |
3238 // We were verifying, but some verification flags got disabled. | |
3239 set_verifying(false); | |
3240 // Exclude symbols, strings and code cache elements from root scanning to | |
3241 // reduce IM and RM pauses. | |
3242 remove_root_scanning_option(rso); | |
3243 } | |
3244 } | |
3245 | |
3246 | |
3247 #ifndef PRODUCT | |
3248 HeapWord* CMSCollector::block_start(const void* p) const { | |
3249 const HeapWord* addr = (HeapWord*)p; | |
3250 if (_span.contains(p)) { | |
3251 if (_cmsGen->cmsSpace()->is_in_reserved(addr)) { | |
3252 return _cmsGen->cmsSpace()->block_start(p); | |
3253 } | |
3254 } | |
3255 return NULL; | |
3256 } | |
3257 #endif | |
3258 | |
3259 HeapWord* | |
3260 ConcurrentMarkSweepGeneration::expand_and_allocate(size_t word_size, | |
3261 bool tlab, | |
3262 bool parallel) { | |
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3263 CMSSynchronousYieldRequest yr; |
0 | 3264 assert(!tlab, "Can't deal with TLAB allocation"); |
3265 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
3266 expand(word_size*HeapWordSize, MinHeapDeltaBytes, | |
3267 CMSExpansionCause::_satisfy_allocation); | |
3268 if (GCExpandToAllocateDelayMillis > 0) { | |
3269 os::sleep(Thread::current(), GCExpandToAllocateDelayMillis, false); | |
3270 } | |
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3271 return have_lock_and_allocate(word_size, tlab); |
0 | 3272 } |
3273 | |
3274 // YSR: All of this generation expansion/shrinking stuff is an exact copy of | |
3275 // OneContigSpaceCardGeneration, which makes me wonder if we should move this | |
3276 // to CardGeneration and share it... | |
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3277 bool ConcurrentMarkSweepGeneration::expand(size_t bytes, size_t expand_bytes) { |
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3278 return CardGeneration::expand(bytes, expand_bytes); |
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3279 } |
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3280 |
0 | 3281 void ConcurrentMarkSweepGeneration::expand(size_t bytes, size_t expand_bytes, |
3282 CMSExpansionCause::Cause cause) | |
3283 { | |
271
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3284 |
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3285 bool success = expand(bytes, expand_bytes); |
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3286 |
0 | 3287 // remember why we expanded; this information is used |
3288 // by shouldConcurrentCollect() when making decisions on whether to start | |
3289 // a new CMS cycle. | |
3290 if (success) { | |
3291 set_expansion_cause(cause); | |
3292 if (PrintGCDetails && Verbose) { | |
3293 gclog_or_tty->print_cr("Expanded CMS gen for %s", | |
3294 CMSExpansionCause::to_string(cause)); | |
3295 } | |
3296 } | |
3297 } | |
3298 | |
3299 HeapWord* ConcurrentMarkSweepGeneration::expand_and_par_lab_allocate(CMSParGCThreadState* ps, size_t word_sz) { | |
3300 HeapWord* res = NULL; | |
3301 MutexLocker x(ParGCRareEvent_lock); | |
3302 while (true) { | |
3303 // Expansion by some other thread might make alloc OK now: | |
3304 res = ps->lab.alloc(word_sz); | |
3305 if (res != NULL) return res; | |
3306 // If there's not enough expansion space available, give up. | |
3307 if (_virtual_space.uncommitted_size() < (word_sz * HeapWordSize)) { | |
3308 return NULL; | |
3309 } | |
3310 // Otherwise, we try expansion. | |
3311 expand(word_sz*HeapWordSize, MinHeapDeltaBytes, | |
3312 CMSExpansionCause::_allocate_par_lab); | |
3313 // Now go around the loop and try alloc again; | |
3314 // A competing par_promote might beat us to the expansion space, | |
3315 // so we may go around the loop again if promotion fails agaion. | |
3316 if (GCExpandToAllocateDelayMillis > 0) { | |
3317 os::sleep(Thread::current(), GCExpandToAllocateDelayMillis, false); | |
3318 } | |
3319 } | |
3320 } | |
3321 | |
3322 | |
3323 bool ConcurrentMarkSweepGeneration::expand_and_ensure_spooling_space( | |
3324 PromotionInfo* promo) { | |
3325 MutexLocker x(ParGCRareEvent_lock); | |
3326 size_t refill_size_bytes = promo->refillSize() * HeapWordSize; | |
3327 while (true) { | |
3328 // Expansion by some other thread might make alloc OK now: | |
3329 if (promo->ensure_spooling_space()) { | |
3330 assert(promo->has_spooling_space(), | |
3331 "Post-condition of successful ensure_spooling_space()"); | |
3332 return true; | |
3333 } | |
3334 // If there's not enough expansion space available, give up. | |
3335 if (_virtual_space.uncommitted_size() < refill_size_bytes) { | |
3336 return false; | |
3337 } | |
3338 // Otherwise, we try expansion. | |
3339 expand(refill_size_bytes, MinHeapDeltaBytes, | |
3340 CMSExpansionCause::_allocate_par_spooling_space); | |
3341 // Now go around the loop and try alloc again; | |
3342 // A competing allocation might beat us to the expansion space, | |
3343 // so we may go around the loop again if allocation fails again. | |
3344 if (GCExpandToAllocateDelayMillis > 0) { | |
3345 os::sleep(Thread::current(), GCExpandToAllocateDelayMillis, false); | |
3346 } | |
3347 } | |
3348 } | |
3349 | |
3350 | |
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3351 void ConcurrentMarkSweepGeneration::shrink_by(size_t bytes) { |
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3352 assert_locked_or_safepoint(ExpandHeap_lock); |
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3353 // Shrink committed space |
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3354 _virtual_space.shrink_by(bytes); |
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3355 // Shrink space; this also shrinks the space's BOT |
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3356 _cmsSpace->set_end((HeapWord*) _virtual_space.high()); |
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3357 size_t new_word_size = heap_word_size(_cmsSpace->capacity()); |
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3358 // Shrink the shared block offset array |
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3359 _bts->resize(new_word_size); |
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3360 MemRegion mr(_cmsSpace->bottom(), new_word_size); |
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3361 // Shrink the card table |
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3362 Universe::heap()->barrier_set()->resize_covered_region(mr); |
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3363 |
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3364 if (Verbose && PrintGC) { |
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3365 size_t new_mem_size = _virtual_space.committed_size(); |
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3366 size_t old_mem_size = new_mem_size + bytes; |
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3367 gclog_or_tty->print_cr("Shrinking %s from " SIZE_FORMAT "K to " SIZE_FORMAT "K", |
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3368 name(), old_mem_size/K, new_mem_size/K); |
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3369 } |
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3370 } |
0 | 3371 |
3372 void ConcurrentMarkSweepGeneration::shrink(size_t bytes) { | |
3373 assert_locked_or_safepoint(Heap_lock); | |
3374 size_t size = ReservedSpace::page_align_size_down(bytes); | |
3375 if (size > 0) { | |
3376 shrink_by(size); | |
3377 } | |
3378 } | |
3379 | |
3380 bool ConcurrentMarkSweepGeneration::grow_by(size_t bytes) { | |
3381 assert_locked_or_safepoint(Heap_lock); | |
3382 bool result = _virtual_space.expand_by(bytes); | |
3383 if (result) { | |
3384 HeapWord* old_end = _cmsSpace->end(); | |
3385 size_t new_word_size = | |
3386 heap_word_size(_virtual_space.committed_size()); | |
3387 MemRegion mr(_cmsSpace->bottom(), new_word_size); | |
3388 _bts->resize(new_word_size); // resize the block offset shared array | |
3389 Universe::heap()->barrier_set()->resize_covered_region(mr); | |
3390 // Hmmmm... why doesn't CFLS::set_end verify locking? | |
3391 // This is quite ugly; FIX ME XXX | |
1145
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6631166: CMS: better heuristics when combatting fragmentation
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1085
diff
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|
3392 _cmsSpace->assert_locked(freelistLock()); |
0 | 3393 _cmsSpace->set_end((HeapWord*)_virtual_space.high()); |
3394 | |
3395 // update the space and generation capacity counters | |
3396 if (UsePerfData) { | |
3397 _space_counters->update_capacity(); | |
3398 _gen_counters->update_all(); | |
3399 } | |
3400 | |
3401 if (Verbose && PrintGC) { | |
3402 size_t new_mem_size = _virtual_space.committed_size(); | |
3403 size_t old_mem_size = new_mem_size - bytes; | |
7623
203f64878aab
7102489: RFE: cleanup jlong typedef on __APPLE__and _LLP64 systems.
hseigel
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6885
diff
changeset
|
3404 gclog_or_tty->print_cr("Expanding %s from " SIZE_FORMAT "K by " SIZE_FORMAT "K to " SIZE_FORMAT "K", |
0 | 3405 name(), old_mem_size/K, bytes/K, new_mem_size/K); |
3406 } | |
3407 } | |
3408 return result; | |
3409 } | |
3410 | |
3411 bool ConcurrentMarkSweepGeneration::grow_to_reserved() { | |
3412 assert_locked_or_safepoint(Heap_lock); | |
3413 bool success = true; | |
3414 const size_t remaining_bytes = _virtual_space.uncommitted_size(); | |
3415 if (remaining_bytes > 0) { | |
3416 success = grow_by(remaining_bytes); | |
3417 DEBUG_ONLY(if (!success) warning("grow to reserved failed");) | |
3418 } | |
3419 return success; | |
3420 } | |
3421 | |
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8008508: CMS does not correctly reduce heap size after a Full GC
jmasa
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diff
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|
3422 void ConcurrentMarkSweepGeneration::shrink_free_list_by(size_t bytes) { |
0 | 3423 assert_locked_or_safepoint(Heap_lock); |
3424 assert_lock_strong(freelistLock()); | |
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diff
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|
3425 if (PrintGCDetails && Verbose) { |
ebded0261dfc
8012111: Remove warning about CMS generation shrinking.
jmasa
parents:
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diff
changeset
|
3426 warning("Shrinking of CMS not yet implemented"); |
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|
3427 } |
0 | 3428 return; |
3429 } | |
3430 | |
3431 | |
3432 // Simple ctor/dtor wrapper for accounting & timer chores around concurrent | |
3433 // phases. | |
3434 class CMSPhaseAccounting: public StackObj { | |
3435 public: | |
3436 CMSPhaseAccounting(CMSCollector *collector, | |
3437 const char *phase, | |
3438 bool print_cr = true); | |
3439 ~CMSPhaseAccounting(); | |
3440 | |
3441 private: | |
3442 CMSCollector *_collector; | |
3443 const char *_phase; | |
3444 elapsedTimer _wallclock; | |
3445 bool _print_cr; | |
3446 | |
3447 public: | |
3448 // Not MT-safe; so do not pass around these StackObj's | |
3449 // where they may be accessed by other threads. | |
3450 jlong wallclock_millis() { | |
3451 assert(_wallclock.is_active(), "Wall clock should not stop"); | |
3452 _wallclock.stop(); // to record time | |
3453 jlong ret = _wallclock.milliseconds(); | |
3454 _wallclock.start(); // restart | |
3455 return ret; | |
3456 } | |
3457 }; | |
3458 | |
3459 CMSPhaseAccounting::CMSPhaseAccounting(CMSCollector *collector, | |
3460 const char *phase, | |
3461 bool print_cr) : | |
3462 _collector(collector), _phase(phase), _print_cr(print_cr) { | |
3463 | |
3464 if (PrintCMSStatistics != 0) { | |
3465 _collector->resetYields(); | |
3466 } | |
8740
62609ffa2fc6
8008684: CMS: concurrent phase start markers should always be printed
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diff
changeset
|
3467 if (PrintGCDetails) { |
0 | 3468 gclog_or_tty->date_stamp(PrintGCDateStamps); |
8740
62609ffa2fc6
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|
3469 gclog_or_tty->stamp(PrintGCTimeStamps); |
62609ffa2fc6
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diff
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|
3470 gclog_or_tty->print_cr("[%s-concurrent-%s-start]", |
0 | 3471 _collector->cmsGen()->short_name(), _phase); |
3472 } | |
3473 _collector->resetTimer(); | |
3474 _wallclock.start(); | |
3475 _collector->startTimer(); | |
3476 } | |
3477 | |
3478 CMSPhaseAccounting::~CMSPhaseAccounting() { | |
3479 assert(_wallclock.is_active(), "Wall clock should not have stopped"); | |
3480 _collector->stopTimer(); | |
3481 _wallclock.stop(); | |
3482 if (PrintGCDetails) { | |
3483 gclog_or_tty->date_stamp(PrintGCDateStamps); | |
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9646b7ff4d14
7198130: G1: PrintReferenceGC output comes out of order
brutisso
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diff
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|
3484 gclog_or_tty->stamp(PrintGCTimeStamps); |
0 | 3485 gclog_or_tty->print("[%s-concurrent-%s: %3.3f/%3.3f secs]", |
3486 _collector->cmsGen()->short_name(), | |
3487 _phase, _collector->timerValue(), _wallclock.seconds()); | |
3488 if (_print_cr) { | |
3489 gclog_or_tty->print_cr(""); | |
3490 } | |
3491 if (PrintCMSStatistics != 0) { | |
3492 gclog_or_tty->print_cr(" (CMS-concurrent-%s yielded %d times)", _phase, | |
3493 _collector->yields()); | |
3494 } | |
3495 } | |
3496 } | |
3497 | |
3498 // CMS work | |
3499 | |
3500 // Checkpoint the roots into this generation from outside | |
3501 // this generation. [Note this initial checkpoint need only | |
3502 // be approximate -- we'll do a catch up phase subsequently.] | |
3503 void CMSCollector::checkpointRootsInitial(bool asynch) { | |
3504 assert(_collectorState == InitialMarking, "Wrong collector state"); | |
3505 check_correct_thread_executing(); | |
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
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3293
diff
changeset
|
3506 TraceCMSMemoryManagerStats tms(_collectorState,GenCollectedHeap::heap()->gc_cause()); |
2125
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6458402: 3 jvmti tests fail with CMS and +ExplicitGCInvokesConcurrent
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diff
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|
3507 |
0 | 3508 ReferenceProcessor* rp = ref_processor(); |
3509 SpecializationStats::clear(); | |
3510 assert(_restart_addr == NULL, "Control point invariant"); | |
3511 if (asynch) { | |
3512 // acquire locks for subsequent manipulations | |
3513 MutexLockerEx x(bitMapLock(), | |
3514 Mutex::_no_safepoint_check_flag); | |
3515 checkpointRootsInitialWork(asynch); | |
3979
4dfb2df418f2
6484982: G1: process references during evacuation pauses
johnc
parents:
3827
diff
changeset
|
3516 // enable ("weak") refs discovery |
4dfb2df418f2
6484982: G1: process references during evacuation pauses
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3827
diff
changeset
|
3517 rp->enable_discovery(true /*verify_disabled*/, true /*check_no_refs*/); |
0 | 3518 _collectorState = Marking; |
3519 } else { | |
3520 // (Weak) Refs discovery: this is controlled from genCollectedHeap::do_collection | |
3521 // which recognizes if we are a CMS generation, and doesn't try to turn on | |
3522 // discovery; verify that they aren't meddling. | |
3523 assert(!rp->discovery_is_atomic(), | |
3524 "incorrect setting of discovery predicate"); | |
3525 assert(!rp->discovery_enabled(), "genCollectedHeap shouldn't control " | |
3526 "ref discovery for this generation kind"); | |
3527 // already have locks | |
3528 checkpointRootsInitialWork(asynch); | |
3979
4dfb2df418f2
6484982: G1: process references during evacuation pauses
johnc
parents:
3827
diff
changeset
|
3529 // now enable ("weak") refs discovery |
4dfb2df418f2
6484982: G1: process references during evacuation pauses
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diff
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|
3530 rp->enable_discovery(true /*verify_disabled*/, false /*verify_no_refs*/); |
0 | 3531 _collectorState = Marking; |
3532 } | |
3533 SpecializationStats::print(); | |
3534 } | |
3535 | |
3536 void CMSCollector::checkpointRootsInitialWork(bool asynch) { | |
3537 assert(SafepointSynchronize::is_at_safepoint(), "world should be stopped"); | |
3538 assert(_collectorState == InitialMarking, "just checking"); | |
3539 | |
3540 // If there has not been a GC[n-1] since last GC[n] cycle completed, | |
3541 // precede our marking with a collection of all | |
3542 // younger generations to keep floating garbage to a minimum. | |
3543 // XXX: we won't do this for now -- it's an optimization to be done later. | |
3544 | |
3545 // already have locks | |
3546 assert_lock_strong(bitMapLock()); | |
3547 assert(_markBitMap.isAllClear(), "was reset at end of previous cycle"); | |
3548 | |
3549 // Setup the verification and class unloading state for this | |
3550 // CMS collection cycle. | |
3551 setup_cms_unloading_and_verification_state(); | |
3552 | |
3553 NOT_PRODUCT(TraceTime t("\ncheckpointRootsInitialWork", | |
3554 PrintGCDetails && Verbose, true, gclog_or_tty);) | |
3555 if (UseAdaptiveSizePolicy) { | |
3556 size_policy()->checkpoint_roots_initial_begin(); | |
3557 } | |
3558 | |
3559 // Reset all the PLAB chunk arrays if necessary. | |
3560 if (_survivor_plab_array != NULL && !CMSPLABRecordAlways) { | |
3561 reset_survivor_plab_arrays(); | |
3562 } | |
3563 | |
3564 ResourceMark rm; | |
3565 HandleMark hm; | |
3566 | |
3567 FalseClosure falseClosure; | |
3568 // In the case of a synchronous collection, we will elide the | |
3569 // 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
|
3570 // in this step. |
753cf9794df9
6885169: merge of 4957990 and 6863023 causes conflict on do_nmethods
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diff
changeset
|
3571 // 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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993
diff
changeset
|
3572 // 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
|
3573 MarkRefsIntoClosure notOlder(_span, &_markBitMap); |
0 | 3574 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
3575 | |
3576 verify_work_stacks_empty(); | |
3577 verify_overflow_empty(); | |
3578 | |
3579 gch->ensure_parsability(false); // fill TLABs, but no need to retire them | |
3580 // Update the saved marks which may affect the root scans. | |
3581 gch->save_marks(); | |
3582 | |
3583 // weak reference processing has not started yet. | |
3584 ref_processor()->set_enqueuing_is_done(false); | |
3585 | |
6725
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
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|
3586 // Need to remember all newly created CLDs, |
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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6197
diff
changeset
|
3587 // 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
|
3588 ClassLoaderDataGraph::remember_new_clds(true); |
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
3589 |
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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diff
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|
3590 // 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
|
3591 // 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
|
3592 ClassLoaderDataGraph::clear_claimed_marks(); |
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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diff
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|
3593 |
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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diff
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|
3594 CMKlassClosure klass_closure(¬Older); |
0 | 3595 { |
3596 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact;) | |
3597 gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel. | |
3598 gch->gen_process_strong_roots(_cmsGen->level(), | |
3599 true, // younger gens are roots | |
989
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
3600 true, // activate StrongRootsScope |
6725
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
3601 false, // not scavenging |
0 | 3602 SharedHeap::ScanningOption(roots_scanning_options()), |
989
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
3603 ¬Older, |
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
3604 true, // walk all of code cache if (so & SO_CodeCache) |
6725
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
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|
3605 NULL, |
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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diff
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|
3606 &klass_closure); |
0 | 3607 } |
3608 | |
3609 // Clear mod-union table; it will be dirtied in the prologue of | |
3610 // CMS generation per each younger generation collection. | |
3611 | |
3612 assert(_modUnionTable.isAllClear(), | |
3613 "Was cleared in most recent final checkpoint phase" | |
3614 " or no bits are set in the gc_prologue before the start of the next " | |
3615 "subsequent marking phase."); | |
3616 | |
6725
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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diff
changeset
|
3617 assert(_ct->klass_rem_set()->mod_union_is_clear(), "Must be"); |
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
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|
3618 |
0 | 3619 // Save the end of the used_region of the constituent generations |
3620 // to be used to limit the extent of sweep in each generation. | |
3621 save_sweep_limits(); | |
3622 if (UseAdaptiveSizePolicy) { | |
3623 size_policy()->checkpoint_roots_initial_end(gch->gc_cause()); | |
3624 } | |
3625 verify_overflow_empty(); | |
3626 } | |
3627 | |
3628 bool CMSCollector::markFromRoots(bool asynch) { | |
3629 // we might be tempted to assert that: | |
3630 // assert(asynch == !SafepointSynchronize::is_at_safepoint(), | |
3631 // "inconsistent argument?"); | |
3632 // However that wouldn't be right, because it's possible that | |
3633 // a safepoint is indeed in progress as a younger generation | |
3634 // stop-the-world GC happens even as we mark in this generation. | |
3635 assert(_collectorState == Marking, "inconsistent state?"); | |
3636 check_correct_thread_executing(); | |
3637 verify_overflow_empty(); | |
3638 | |
3639 bool res; | |
3640 if (asynch) { | |
3641 | |
3642 // Start the timers for adaptive size policy for the concurrent phases | |
3643 // Do it here so that the foreground MS can use the concurrent | |
3644 // timer since a foreground MS might has the sweep done concurrently | |
3645 // or STW. | |
3646 if (UseAdaptiveSizePolicy) { | |
3647 size_policy()->concurrent_marking_begin(); | |
3648 } | |
3649 | |
3650 // Weak ref discovery note: We may be discovering weak | |
3651 // refs in this generation concurrent (but interleaved) with | |
3652 // weak ref discovery by a younger generation collector. | |
3653 | |
3654 CMSTokenSyncWithLocks ts(true, bitMapLock()); | |
3655 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
3656 CMSPhaseAccounting pa(this, "mark", !PrintGCDetails); | |
3657 res = markFromRootsWork(asynch); | |
3658 if (res) { | |
3659 _collectorState = Precleaning; | |
3660 } else { // We failed and a foreground collection wants to take over | |
3661 assert(_foregroundGCIsActive, "internal state inconsistency"); | |
3662 assert(_restart_addr == NULL, "foreground will restart from scratch"); | |
3663 if (PrintGCDetails) { | |
3664 gclog_or_tty->print_cr("bailing out to foreground collection"); | |
3665 } | |
3666 } | |
3667 if (UseAdaptiveSizePolicy) { | |
3668 size_policy()->concurrent_marking_end(); | |
3669 } | |
3670 } else { | |
3671 assert(SafepointSynchronize::is_at_safepoint(), | |
3672 "inconsistent with asynch == false"); | |
3673 if (UseAdaptiveSizePolicy) { | |
3674 size_policy()->ms_collection_marking_begin(); | |
3675 } | |
3676 // already have locks | |
3677 res = markFromRootsWork(asynch); | |
3678 _collectorState = FinalMarking; | |
3679 if (UseAdaptiveSizePolicy) { | |
3680 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
3681 size_policy()->ms_collection_marking_end(gch->gc_cause()); | |
3682 } | |
3683 } | |
3684 verify_overflow_empty(); | |
3685 return res; | |
3686 } | |
3687 | |
3688 bool CMSCollector::markFromRootsWork(bool asynch) { | |
3689 // iterate over marked bits in bit map, doing a full scan and mark | |
3690 // from these roots using the following algorithm: | |
3691 // . if oop is to the right of the current scan pointer, | |
3692 // mark corresponding bit (we'll process it later) | |
3693 // . else (oop is to left of current scan pointer) | |
3694 // push oop on marking stack | |
3695 // . drain the marking stack | |
3696 | |
3697 // Note that when we do a marking step we need to hold the | |
3698 // bit map lock -- recall that direct allocation (by mutators) | |
3699 // and promotion (by younger generation collectors) is also | |
3700 // marking the bit map. [the so-called allocate live policy.] | |
3701 // Because the implementation of bit map marking is not | |
3702 // robust wrt simultaneous marking of bits in the same word, | |
3703 // we need to make sure that there is no such interference | |
3704 // between concurrent such updates. | |
3705 | |
3706 // already have locks | |
3707 assert_lock_strong(bitMapLock()); | |
3708 | |
3709 verify_work_stacks_empty(); | |
3710 verify_overflow_empty(); | |
3711 bool result = false; | |
1284 | 3712 if (CMSConcurrentMTEnabled && ConcGCThreads > 0) { |
0 | 3713 result = do_marking_mt(asynch); |
3714 } else { | |
3715 result = do_marking_st(asynch); | |
3716 } | |
3717 return result; | |
3718 } | |
3719 | |
3720 // Forward decl | |
3721 class CMSConcMarkingTask; | |
3722 | |
3723 class CMSConcMarkingTerminator: public ParallelTaskTerminator { | |
3724 CMSCollector* _collector; | |
3725 CMSConcMarkingTask* _task; | |
1837
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|
3726 public: |
0 | 3727 virtual void yield(); |
1837
c99c53f07c14
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diff
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|
3728 |
0 | 3729 // "n_threads" is the number of threads to be terminated. |
3730 // "queue_set" is a set of work queues of other threads. | |
3731 // "collector" is the CMS collector associated with this task terminator. | |
3732 // "yield" indicates whether we need the gang as a whole to yield. | |
1837
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diff
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|
3733 CMSConcMarkingTerminator(int n_threads, TaskQueueSetSuper* queue_set, CMSCollector* collector) : |
0 | 3734 ParallelTaskTerminator(n_threads, queue_set), |
1837
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diff
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|
3735 _collector(collector) { } |
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6692906: CMS: parallel concurrent marking may be prone to hanging or stalling mutators for periods of time
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1836
diff
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|
3736 |
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6692906: CMS: parallel concurrent marking may be prone to hanging or stalling mutators for periods of time
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diff
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|
3737 void set_task(CMSConcMarkingTask* task) { |
c99c53f07c14
6692906: CMS: parallel concurrent marking may be prone to hanging or stalling mutators for periods of time
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1836
diff
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|
3738 _task = task; |
c99c53f07c14
6692906: CMS: parallel concurrent marking may be prone to hanging or stalling mutators for periods of time
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1836
diff
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|
3739 } |
c99c53f07c14
6692906: CMS: parallel concurrent marking may be prone to hanging or stalling mutators for periods of time
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1836
diff
changeset
|
3740 }; |
c99c53f07c14
6692906: CMS: parallel concurrent marking may be prone to hanging or stalling mutators for periods of time
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1836
diff
changeset
|
3741 |
c99c53f07c14
6692906: CMS: parallel concurrent marking may be prone to hanging or stalling mutators for periods of time
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diff
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|
3742 class CMSConcMarkingTerminatorTerminator: public TerminatorTerminator { |
c99c53f07c14
6692906: CMS: parallel concurrent marking may be prone to hanging or stalling mutators for periods of time
ysr
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1836
diff
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|
3743 CMSConcMarkingTask* _task; |
c99c53f07c14
6692906: CMS: parallel concurrent marking may be prone to hanging or stalling mutators for periods of time
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|
3744 public: |
c99c53f07c14
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3745 bool should_exit_termination(); |
0 | 3746 void set_task(CMSConcMarkingTask* task) { |
3747 _task = task; | |
3748 } | |
3749 }; | |
3750 | |
3751 // MT Concurrent Marking Task | |
3752 class CMSConcMarkingTask: public YieldingFlexibleGangTask { | |
3753 CMSCollector* _collector; | |
3754 int _n_workers; // requested/desired # workers | |
3755 bool _asynch; | |
3756 bool _result; | |
3757 CompactibleFreeListSpace* _cms_space; | |
1837
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3758 char _pad_front[64]; // padding to ... |
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3759 HeapWord* _global_finger; // ... avoid sharing cache line |
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3760 char _pad_back[64]; |
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3761 HeapWord* _restart_addr; |
0 | 3762 |
3763 // Exposed here for yielding support | |
3764 Mutex* const _bit_map_lock; | |
3765 | |
3766 // The per thread work queues, available here for stealing | |
3767 OopTaskQueueSet* _task_queues; | |
1837
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3768 |
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3769 // Termination (and yielding) support |
0 | 3770 CMSConcMarkingTerminator _term; |
1837
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3771 CMSConcMarkingTerminatorTerminator _term_term; |
0 | 3772 |
3773 public: | |
3774 CMSConcMarkingTask(CMSCollector* collector, | |
3775 CompactibleFreeListSpace* cms_space, | |
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3776 bool asynch, |
0 | 3777 YieldingFlexibleWorkGang* workers, |
3778 OopTaskQueueSet* task_queues): | |
3779 YieldingFlexibleGangTask("Concurrent marking done multi-threaded"), | |
3780 _collector(collector), | |
3781 _cms_space(cms_space), | |
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3782 _asynch(asynch), _n_workers(0), _result(true), |
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3783 _task_queues(task_queues), |
1837
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3784 _term(_n_workers, task_queues, _collector), |
0 | 3785 _bit_map_lock(collector->bitMapLock()) |
3786 { | |
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3787 _requested_size = _n_workers; |
0 | 3788 _term.set_task(this); |
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3789 _term_term.set_task(this); |
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3790 _restart_addr = _global_finger = _cms_space->bottom(); |
0 | 3791 } |
3792 | |
3793 | |
3794 OopTaskQueueSet* task_queues() { return _task_queues; } | |
3795 | |
3796 OopTaskQueue* work_queue(int i) { return task_queues()->queue(i); } | |
3797 | |
3798 HeapWord** global_finger_addr() { return &_global_finger; } | |
3799 | |
3800 CMSConcMarkingTerminator* terminator() { return &_term; } | |
3801 | |
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3802 virtual void set_for_termination(int active_workers) { |
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3803 terminator()->reset_for_reuse(active_workers); |
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3804 } |
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3805 |
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3806 void work(uint worker_id); |
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3807 bool should_yield() { |
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3808 return ConcurrentMarkSweepThread::should_yield() |
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3809 && !_collector->foregroundGCIsActive() |
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3810 && _asynch; |
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3811 } |
0 | 3812 |
3813 virtual void coordinator_yield(); // stuff done by coordinator | |
3814 bool result() { return _result; } | |
3815 | |
3816 void reset(HeapWord* ra) { | |
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3817 assert(_global_finger >= _cms_space->end(), "Postcondition of ::work(i)"); |
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3818 _restart_addr = _global_finger = ra; |
0 | 3819 _term.reset_for_reuse(); |
3820 } | |
3821 | |
3822 static bool get_work_from_overflow_stack(CMSMarkStack* ovflw_stk, | |
3823 OopTaskQueue* work_q); | |
3824 | |
3825 private: | |
3826 void do_scan_and_mark(int i, CompactibleFreeListSpace* sp); | |
3827 void do_work_steal(int i); | |
3828 void bump_global_finger(HeapWord* f); | |
3829 }; | |
3830 | |
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3831 bool CMSConcMarkingTerminatorTerminator::should_exit_termination() { |
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3832 assert(_task != NULL, "Error"); |
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3833 return _task->yielding(); |
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3834 // Note that we do not need the disjunct || _task->should_yield() above |
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3835 // because we want terminating threads to yield only if the task |
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3836 // is already in the midst of yielding, which happens only after at least one |
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3837 // thread has yielded. |
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3838 } |
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3839 |
0 | 3840 void CMSConcMarkingTerminator::yield() { |
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3841 if (_task->should_yield()) { |
0 | 3842 _task->yield(); |
3843 } else { | |
3844 ParallelTaskTerminator::yield(); | |
3845 } | |
3846 } | |
3847 | |
3848 //////////////////////////////////////////////////////////////// | |
3849 // Concurrent Marking Algorithm Sketch | |
3850 //////////////////////////////////////////////////////////////// | |
3851 // Until all tasks exhausted (both spaces): | |
3852 // -- claim next available chunk | |
3853 // -- bump global finger via CAS | |
3854 // -- find first object that starts in this chunk | |
3855 // and start scanning bitmap from that position | |
3856 // -- scan marked objects for oops | |
3857 // -- CAS-mark target, and if successful: | |
3858 // . if target oop is above global finger (volatile read) | |
3859 // nothing to do | |
3860 // . if target oop is in chunk and above local finger | |
3861 // then nothing to do | |
3862 // . else push on work-queue | |
3863 // -- Deal with possible overflow issues: | |
3864 // . local work-queue overflow causes stuff to be pushed on | |
3865 // global (common) overflow queue | |
3866 // . always first empty local work queue | |
3867 // . then get a batch of oops from global work queue if any | |
3868 // . then do work stealing | |
3869 // -- When all tasks claimed (both spaces) | |
3870 // and local work queue empty, | |
3871 // then in a loop do: | |
3872 // . check global overflow stack; steal a batch of oops and trace | |
3873 // . try to steal from other threads oif GOS is empty | |
3874 // . if neither is available, offer termination | |
3875 // -- Terminate and return result | |
3876 // | |
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3877 void CMSConcMarkingTask::work(uint worker_id) { |
0 | 3878 elapsedTimer _timer; |
3879 ResourceMark rm; | |
3880 HandleMark hm; | |
3881 | |
3882 DEBUG_ONLY(_collector->verify_overflow_empty();) | |
3883 | |
3884 // Before we begin work, our work queue should be empty | |
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3885 assert(work_queue(worker_id)->size() == 0, "Expected to be empty"); |
0 | 3886 // Scan the bitmap covering _cms_space, tracing through grey objects. |
3887 _timer.start(); | |
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3888 do_scan_and_mark(worker_id, _cms_space); |
0 | 3889 _timer.stop(); |
3890 if (PrintCMSStatistics != 0) { | |
3891 gclog_or_tty->print_cr("Finished cms space scanning in %dth thread: %3.3f sec", | |
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3892 worker_id, _timer.seconds()); |
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3893 // XXX: need xxx/xxx type of notation, two timers |
0 | 3894 } |
3895 | |
3896 // ... do work stealing | |
3897 _timer.reset(); | |
3898 _timer.start(); | |
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3899 do_work_steal(worker_id); |
0 | 3900 _timer.stop(); |
3901 if (PrintCMSStatistics != 0) { | |
3902 gclog_or_tty->print_cr("Finished work stealing in %dth thread: %3.3f sec", | |
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3903 worker_id, _timer.seconds()); |
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3904 // XXX: need xxx/xxx type of notation, two timers |
0 | 3905 } |
3906 assert(_collector->_markStack.isEmpty(), "Should have been emptied"); | |
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3907 assert(work_queue(worker_id)->size() == 0, "Should have been emptied"); |
0 | 3908 // Note that under the current task protocol, the |
3909 // following assertion is true even of the spaces | |
3910 // expanded since the completion of the concurrent | |
3911 // marking. XXX This will likely change under a strict | |
3912 // ABORT semantics. | |
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3913 // After perm removal the comparison was changed to |
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3914 // greater than or equal to from strictly greater than. |
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3915 // Before perm removal the highest address sweep would |
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3916 // have been at the end of perm gen but now is at the |
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3917 // end of the tenured gen. |
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3918 assert(_global_finger >= _cms_space->end(), |
0 | 3919 "All tasks have been completed"); |
3920 DEBUG_ONLY(_collector->verify_overflow_empty();) | |
3921 } | |
3922 | |
3923 void CMSConcMarkingTask::bump_global_finger(HeapWord* f) { | |
3924 HeapWord* read = _global_finger; | |
3925 HeapWord* cur = read; | |
3926 while (f > read) { | |
3927 cur = read; | |
3928 read = (HeapWord*) Atomic::cmpxchg_ptr(f, &_global_finger, cur); | |
3929 if (cur == read) { | |
3930 // our cas succeeded | |
3931 assert(_global_finger >= f, "protocol consistency"); | |
3932 break; | |
3933 } | |
3934 } | |
3935 } | |
3936 | |
3937 // This is really inefficient, and should be redone by | |
3938 // using (not yet available) block-read and -write interfaces to the | |
3939 // stack and the work_queue. XXX FIX ME !!! | |
3940 bool CMSConcMarkingTask::get_work_from_overflow_stack(CMSMarkStack* ovflw_stk, | |
3941 OopTaskQueue* work_q) { | |
3942 // Fast lock-free check | |
3943 if (ovflw_stk->length() == 0) { | |
3944 return false; | |
3945 } | |
3946 assert(work_q->size() == 0, "Shouldn't steal"); | |
3947 MutexLockerEx ml(ovflw_stk->par_lock(), | |
3948 Mutex::_no_safepoint_check_flag); | |
3949 // Grab up to 1/4 the size of the work queue | |
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3950 size_t num = MIN2((size_t)(work_q->max_elems() - work_q->size())/4, |
0 | 3951 (size_t)ParGCDesiredObjsFromOverflowList); |
3952 num = MIN2(num, ovflw_stk->length()); | |
3953 for (int i = (int) num; i > 0; i--) { | |
3954 oop cur = ovflw_stk->pop(); | |
3955 assert(cur != NULL, "Counted wrong?"); | |
3956 work_q->push(cur); | |
3957 } | |
3958 return num > 0; | |
3959 } | |
3960 | |
3961 void CMSConcMarkingTask::do_scan_and_mark(int i, CompactibleFreeListSpace* sp) { | |
3962 SequentialSubTasksDone* pst = sp->conc_par_seq_tasks(); | |
3963 int n_tasks = pst->n_tasks(); | |
3964 // We allow that there may be no tasks to do here because | |
3965 // we are restarting after a stack overflow. | |
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3966 assert(pst->valid() || n_tasks == 0, "Uninitialized use?"); |
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3967 uint nth_task = 0; |
0 | 3968 |
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3969 HeapWord* aligned_start = sp->bottom(); |
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3970 if (sp->used_region().contains(_restart_addr)) { |
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3971 // Align down to a card boundary for the start of 0th task |
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3972 // for this space. |
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3973 aligned_start = |
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3974 (HeapWord*)align_size_down((uintptr_t)_restart_addr, |
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3975 CardTableModRefBS::card_size); |
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3976 } |
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3977 |
0 | 3978 size_t chunk_size = sp->marking_task_size(); |
3979 while (!pst->is_task_claimed(/* reference */ nth_task)) { | |
3980 // Having claimed the nth task in this space, | |
3981 // compute the chunk that it corresponds to: | |
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3982 MemRegion span = MemRegion(aligned_start + nth_task*chunk_size, |
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3983 aligned_start + (nth_task+1)*chunk_size); |
0 | 3984 // Try and bump the global finger via a CAS; |
3985 // note that we need to do the global finger bump | |
3986 // _before_ taking the intersection below, because | |
3987 // the task corresponding to that region will be | |
3988 // deemed done even if the used_region() expands | |
3989 // because of allocation -- as it almost certainly will | |
3990 // during start-up while the threads yield in the | |
3991 // closure below. | |
3992 HeapWord* finger = span.end(); | |
3993 bump_global_finger(finger); // atomically | |
3994 // There are null tasks here corresponding to chunks | |
3995 // beyond the "top" address of the space. | |
3996 span = span.intersection(sp->used_region()); | |
3997 if (!span.is_empty()) { // Non-null task | |
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3998 HeapWord* prev_obj; |
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3999 assert(!span.contains(_restart_addr) || nth_task == 0, |
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4000 "Inconsistency"); |
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4001 if (nth_task == 0) { |
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4002 // For the 0th task, we'll not need to compute a block_start. |
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4003 if (span.contains(_restart_addr)) { |
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4004 // In the case of a restart because of stack overflow, |
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4005 // we might additionally skip a chunk prefix. |
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4006 prev_obj = _restart_addr; |
0 | 4007 } else { |
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4008 prev_obj = span.start(); |
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4009 } |
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4010 } else { |
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4011 // We want to skip the first object because |
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4012 // the protocol is to scan any object in its entirety |
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4013 // that _starts_ in this span; a fortiori, any |
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4014 // object starting in an earlier span is scanned |
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4015 // as part of an earlier claimed task. |
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4016 // Below we use the "careful" version of block_start |
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4017 // so we do not try to navigate uninitialized objects. |
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4018 prev_obj = sp->block_start_careful(span.start()); |
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4019 // Below we use a variant of block_size that uses the |
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4020 // Printezis bits to avoid waiting for allocated |
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4021 // objects to become initialized/parsable. |
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4022 while (prev_obj < span.start()) { |
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4023 size_t sz = sp->block_size_no_stall(prev_obj, _collector); |
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4024 if (sz > 0) { |
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4025 prev_obj += sz; |
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4026 } else { |
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4027 // In this case we may end up doing a bit of redundant |
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4028 // scanning, but that appears unavoidable, short of |
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4029 // locking the free list locks; see bug 6324141. |
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4030 break; |
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4031 } |
0 | 4032 } |
4033 } | |
4034 if (prev_obj < span.end()) { | |
4035 MemRegion my_span = MemRegion(prev_obj, span.end()); | |
4036 // Do the marking work within a non-empty span -- | |
4037 // the last argument to the constructor indicates whether the | |
4038 // iteration should be incremental with periodic yields. | |
4039 Par_MarkFromRootsClosure cl(this, _collector, my_span, | |
4040 &_collector->_markBitMap, | |
4041 work_queue(i), | |
4042 &_collector->_markStack, | |
4043 _asynch); | |
4044 _collector->_markBitMap.iterate(&cl, my_span.start(), my_span.end()); | |
4045 } // else nothing to do for this task | |
4046 } // else nothing to do for this task | |
4047 } | |
4048 // We'd be tempted to assert here that since there are no | |
4049 // more tasks left to claim in this space, the global_finger | |
4050 // must exceed space->top() and a fortiori space->end(). However, | |
4051 // that would not quite be correct because the bumping of | |
4052 // global_finger occurs strictly after the claiming of a task, | |
4053 // so by the time we reach here the global finger may not yet | |
4054 // have been bumped up by the thread that claimed the last | |
4055 // task. | |
4056 pst->all_tasks_completed(); | |
4057 } | |
4058 | |
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4059 class Par_ConcMarkingClosure: public CMSOopClosure { |
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4060 private: |
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4061 CMSCollector* _collector; |
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4062 CMSConcMarkingTask* _task; |
0 | 4063 MemRegion _span; |
4064 CMSBitMap* _bit_map; | |
4065 CMSMarkStack* _overflow_stack; | |
4066 OopTaskQueue* _work_queue; | |
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4067 protected: |
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4068 DO_OOP_WORK_DEFN |
0 | 4069 public: |
1837
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4070 Par_ConcMarkingClosure(CMSCollector* collector, CMSConcMarkingTask* task, OopTaskQueue* work_queue, |
6725
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4071 CMSBitMap* bit_map, CMSMarkStack* overflow_stack): |
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4072 CMSOopClosure(collector->ref_processor()), |
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4073 _collector(collector), |
1837
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4074 _task(task), |
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4075 _span(collector->_span), |
0 | 4076 _work_queue(work_queue), |
4077 _bit_map(bit_map), | |
935 | 4078 _overflow_stack(overflow_stack) |
4079 { } | |
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4080 virtual void do_oop(oop* p); |
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4081 virtual void do_oop(narrowOop* p); |
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4082 |
0 | 4083 void trim_queue(size_t max); |
4084 void handle_stack_overflow(HeapWord* lost); | |
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4085 void do_yield_check() { |
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4086 if (_task->should_yield()) { |
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4087 _task->yield(); |
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4088 } |
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4089 } |
0 | 4090 }; |
4091 | |
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4092 // Grey object scanning during work stealing phase -- |
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4093 // the salient assumption here is that any references |
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4094 // that are in these stolen objects being scanned must |
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4095 // already have been initialized (else they would not have |
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4096 // been published), so we do not need to check for |
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4097 // uninitialized objects before pushing here. |
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4098 void Par_ConcMarkingClosure::do_oop(oop obj) { |
340
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4099 assert(obj->is_oop_or_null(true), "expected an oop or NULL"); |
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4100 HeapWord* addr = (HeapWord*)obj; |
0 | 4101 // Check if oop points into the CMS generation |
4102 // and is not marked | |
4103 if (_span.contains(addr) && !_bit_map->isMarked(addr)) { | |
4104 // a white object ... | |
4105 // If we manage to "claim" the object, by being the | |
4106 // first thread to mark it, then we push it on our | |
4107 // marking stack | |
4108 if (_bit_map->par_mark(addr)) { // ... now grey | |
4109 // push on work queue (grey set) | |
4110 bool simulate_overflow = false; | |
4111 NOT_PRODUCT( | |
4112 if (CMSMarkStackOverflowALot && | |
4113 _collector->simulate_overflow()) { | |
4114 // simulate a stack overflow | |
4115 simulate_overflow = true; | |
4116 } | |
4117 ) | |
4118 if (simulate_overflow || | |
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4119 !(_work_queue->push(obj) || _overflow_stack->par_push(obj))) { |
0 | 4120 // stack overflow |
4121 if (PrintCMSStatistics != 0) { | |
4122 gclog_or_tty->print_cr("CMS marking stack overflow (benign) at " | |
4123 SIZE_FORMAT, _overflow_stack->capacity()); | |
4124 } | |
4125 // We cannot assert that the overflow stack is full because | |
4126 // it may have been emptied since. | |
4127 assert(simulate_overflow || | |
4128 _work_queue->size() == _work_queue->max_elems(), | |
4129 "Else push should have succeeded"); | |
4130 handle_stack_overflow(addr); | |
4131 } | |
4132 } // Else, some other thread got there first | |
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4133 do_yield_check(); |
0 | 4134 } |
4135 } | |
4136 | |
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4137 void Par_ConcMarkingClosure::do_oop(oop* p) { Par_ConcMarkingClosure::do_oop_work(p); } |
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4138 void Par_ConcMarkingClosure::do_oop(narrowOop* p) { Par_ConcMarkingClosure::do_oop_work(p); } |
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4139 |
0 | 4140 void Par_ConcMarkingClosure::trim_queue(size_t max) { |
4141 while (_work_queue->size() > max) { | |
4142 oop new_oop; | |
4143 if (_work_queue->pop_local(new_oop)) { | |
4144 assert(new_oop->is_oop(), "Should be an oop"); | |
4145 assert(_bit_map->isMarked((HeapWord*)new_oop), "Grey object"); | |
4146 assert(_span.contains((HeapWord*)new_oop), "Not in span"); | |
4147 new_oop->oop_iterate(this); // do_oop() above | |
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4148 do_yield_check(); |
0 | 4149 } |
4150 } | |
4151 } | |
4152 | |
4153 // Upon stack overflow, we discard (part of) the stack, | |
4154 // remembering the least address amongst those discarded | |
4155 // in CMSCollector's _restart_address. | |
4156 void Par_ConcMarkingClosure::handle_stack_overflow(HeapWord* lost) { | |
4157 // We need to do this under a mutex to prevent other | |
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4158 // workers from interfering with the work done below. |
0 | 4159 MutexLockerEx ml(_overflow_stack->par_lock(), |
4160 Mutex::_no_safepoint_check_flag); | |
4161 // Remember the least grey address discarded | |
4162 HeapWord* ra = (HeapWord*)_overflow_stack->least_value(lost); | |
4163 _collector->lower_restart_addr(ra); | |
4164 _overflow_stack->reset(); // discard stack contents | |
4165 _overflow_stack->expand(); // expand the stack if possible | |
4166 } | |
4167 | |
4168 | |
4169 void CMSConcMarkingTask::do_work_steal(int i) { | |
4170 OopTaskQueue* work_q = work_queue(i); | |
4171 oop obj_to_scan; | |
4172 CMSBitMap* bm = &(_collector->_markBitMap); | |
4173 CMSMarkStack* ovflw = &(_collector->_markStack); | |
4174 int* seed = _collector->hash_seed(i); | |
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4175 Par_ConcMarkingClosure cl(_collector, this, work_q, bm, ovflw); |
0 | 4176 while (true) { |
4177 cl.trim_queue(0); | |
4178 assert(work_q->size() == 0, "Should have been emptied above"); | |
4179 if (get_work_from_overflow_stack(ovflw, work_q)) { | |
4180 // Can't assert below because the work obtained from the | |
4181 // overflow stack may already have been stolen from us. | |
4182 // assert(work_q->size() > 0, "Work from overflow stack"); | |
4183 continue; | |
4184 } else if (task_queues()->steal(i, seed, /* reference */ obj_to_scan)) { | |
4185 assert(obj_to_scan->is_oop(), "Should be an oop"); | |
4186 assert(bm->isMarked((HeapWord*)obj_to_scan), "Grey object"); | |
4187 obj_to_scan->oop_iterate(&cl); | |
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4188 } else if (terminator()->offer_termination(&_term_term)) { |
0 | 4189 assert(work_q->size() == 0, "Impossible!"); |
4190 break; | |
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4191 } else if (yielding() || should_yield()) { |
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4192 yield(); |
0 | 4193 } |
4194 } | |
4195 } | |
4196 | |
4197 // This is run by the CMS (coordinator) thread. | |
4198 void CMSConcMarkingTask::coordinator_yield() { | |
4199 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
4200 "CMS thread should hold CMS token"); | |
4201 // First give up the locks, then yield, then re-lock | |
4202 // We should probably use a constructor/destructor idiom to | |
4203 // do this unlock/lock or modify the MutexUnlocker class to | |
4204 // serve our purpose. XXX | |
4205 assert_lock_strong(_bit_map_lock); | |
4206 _bit_map_lock->unlock(); | |
4207 ConcurrentMarkSweepThread::desynchronize(true); | |
4208 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
4209 _collector->stopTimer(); | |
4210 if (PrintCMSStatistics != 0) { | |
4211 _collector->incrementYields(); | |
4212 } | |
4213 _collector->icms_wait(); | |
4214 | |
4215 // It is possible for whichever thread initiated the yield request | |
4216 // not to get a chance to wake up and take the bitmap lock between | |
4217 // this thread releasing it and reacquiring it. So, while the | |
4218 // should_yield() flag is on, let's sleep for a bit to give the | |
4219 // other thread a chance to wake up. The limit imposed on the number | |
4220 // of iterations is defensive, to avoid any unforseen circumstances | |
4221 // putting us into an infinite loop. Since it's always been this | |
4222 // (coordinator_yield()) method that was observed to cause the | |
4223 // problem, we are using a parameter (CMSCoordinatorYieldSleepCount) | |
4224 // which is by default non-zero. For the other seven methods that | |
4225 // also perform the yield operation, as are using a different | |
4226 // parameter (CMSYieldSleepCount) which is by default zero. This way we | |
4227 // can enable the sleeping for those methods too, if necessary. | |
4228 // See 6442774. | |
4229 // | |
4230 // We really need to reconsider the synchronization between the GC | |
4231 // thread and the yield-requesting threads in the future and we | |
4232 // should really use wait/notify, which is the recommended | |
4233 // way of doing this type of interaction. Additionally, we should | |
4234 // consolidate the eight methods that do the yield operation and they | |
4235 // are almost identical into one for better maintenability and | |
4236 // readability. See 6445193. | |
4237 // | |
4238 // Tony 2006.06.29 | |
4239 for (unsigned i = 0; i < CMSCoordinatorYieldSleepCount && | |
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4240 ConcurrentMarkSweepThread::should_yield() && |
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4241 !CMSCollector::foregroundGCIsActive(); ++i) { |
0 | 4242 os::sleep(Thread::current(), 1, false); |
4243 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
4244 } | |
4245 | |
4246 ConcurrentMarkSweepThread::synchronize(true); | |
4247 _bit_map_lock->lock_without_safepoint_check(); | |
4248 _collector->startTimer(); | |
4249 } | |
4250 | |
4251 bool CMSCollector::do_marking_mt(bool asynch) { | |
1284 | 4252 assert(ConcGCThreads > 0 && conc_workers() != NULL, "precondition"); |
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4253 int num_workers = AdaptiveSizePolicy::calc_active_conc_workers( |
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4254 conc_workers()->total_workers(), |
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4255 conc_workers()->active_workers(), |
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4256 Threads::number_of_non_daemon_threads()); |
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4257 conc_workers()->set_active_workers(num_workers); |
0 | 4258 |
4259 CompactibleFreeListSpace* cms_space = _cmsGen->cmsSpace(); | |
4260 | |
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4261 CMSConcMarkingTask tsk(this, |
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4262 cms_space, |
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4263 asynch, |
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4264 conc_workers(), |
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4265 task_queues()); |
0 | 4266 |
4267 // Since the actual number of workers we get may be different | |
4268 // from the number we requested above, do we need to do anything different | |
4269 // below? In particular, may be we need to subclass the SequantialSubTasksDone | |
4270 // class?? XXX | |
4271 cms_space ->initialize_sequential_subtasks_for_marking(num_workers); | |
4272 | |
4273 // Refs discovery is already non-atomic. | |
4274 assert(!ref_processor()->discovery_is_atomic(), "Should be non-atomic"); | |
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4275 assert(ref_processor()->discovery_is_mt(), "Discovery should be MT"); |
0 | 4276 conc_workers()->start_task(&tsk); |
4277 while (tsk.yielded()) { | |
4278 tsk.coordinator_yield(); | |
4279 conc_workers()->continue_task(&tsk); | |
4280 } | |
4281 // If the task was aborted, _restart_addr will be non-NULL | |
4282 assert(tsk.completed() || _restart_addr != NULL, "Inconsistency"); | |
4283 while (_restart_addr != NULL) { | |
4284 // XXX For now we do not make use of ABORTED state and have not | |
4285 // yet implemented the right abort semantics (even in the original | |
4286 // single-threaded CMS case). That needs some more investigation | |
4287 // and is deferred for now; see CR# TBF. 07252005YSR. XXX | |
4288 assert(!CMSAbortSemantics || tsk.aborted(), "Inconsistency"); | |
4289 // If _restart_addr is non-NULL, a marking stack overflow | |
605 | 4290 // occurred; we need to do a fresh marking iteration from the |
0 | 4291 // indicated restart address. |
4292 if (_foregroundGCIsActive && asynch) { | |
4293 // We may be running into repeated stack overflows, having | |
4294 // reached the limit of the stack size, while making very | |
4295 // slow forward progress. It may be best to bail out and | |
4296 // let the foreground collector do its job. | |
4297 // Clear _restart_addr, so that foreground GC | |
4298 // works from scratch. This avoids the headache of | |
4299 // a "rescan" which would otherwise be needed because | |
4300 // of the dirty mod union table & card table. | |
4301 _restart_addr = NULL; | |
4302 return false; | |
4303 } | |
4304 // Adjust the task to restart from _restart_addr | |
4305 tsk.reset(_restart_addr); | |
4306 cms_space ->initialize_sequential_subtasks_for_marking(num_workers, | |
4307 _restart_addr); | |
4308 _restart_addr = NULL; | |
4309 // Get the workers going again | |
4310 conc_workers()->start_task(&tsk); | |
4311 while (tsk.yielded()) { | |
4312 tsk.coordinator_yield(); | |
4313 conc_workers()->continue_task(&tsk); | |
4314 } | |
4315 } | |
4316 assert(tsk.completed(), "Inconsistency"); | |
4317 assert(tsk.result() == true, "Inconsistency"); | |
4318 return true; | |
4319 } | |
4320 | |
4321 bool CMSCollector::do_marking_st(bool asynch) { | |
4322 ResourceMark rm; | |
4323 HandleMark hm; | |
4324 | |
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4325 // Temporarily make refs discovery single threaded (non-MT) |
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4326 ReferenceProcessorMTDiscoveryMutator rp_mut_discovery(ref_processor(), false); |
0 | 4327 MarkFromRootsClosure markFromRootsClosure(this, _span, &_markBitMap, |
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4328 &_markStack, CMSYield && asynch); |
0 | 4329 // the last argument to iterate indicates whether the iteration |
4330 // should be incremental with periodic yields. | |
4331 _markBitMap.iterate(&markFromRootsClosure); | |
4332 // If _restart_addr is non-NULL, a marking stack overflow | |
605 | 4333 // occurred; we need to do a fresh iteration from the |
0 | 4334 // indicated restart address. |
4335 while (_restart_addr != NULL) { | |
4336 if (_foregroundGCIsActive && asynch) { | |
4337 // We may be running into repeated stack overflows, having | |
4338 // reached the limit of the stack size, while making very | |
4339 // slow forward progress. It may be best to bail out and | |
4340 // let the foreground collector do its job. | |
4341 // Clear _restart_addr, so that foreground GC | |
4342 // works from scratch. This avoids the headache of | |
4343 // a "rescan" which would otherwise be needed because | |
4344 // of the dirty mod union table & card table. | |
4345 _restart_addr = NULL; | |
4346 return false; // indicating failure to complete marking | |
4347 } | |
4348 // Deal with stack overflow: | |
4349 // we restart marking from _restart_addr | |
4350 HeapWord* ra = _restart_addr; | |
4351 markFromRootsClosure.reset(ra); | |
4352 _restart_addr = NULL; | |
4353 _markBitMap.iterate(&markFromRootsClosure, ra, _span.end()); | |
4354 } | |
4355 return true; | |
4356 } | |
4357 | |
4358 void CMSCollector::preclean() { | |
4359 check_correct_thread_executing(); | |
4360 assert(Thread::current()->is_ConcurrentGC_thread(), "Wrong thread"); | |
4361 verify_work_stacks_empty(); | |
4362 verify_overflow_empty(); | |
4363 _abort_preclean = false; | |
4364 if (CMSPrecleaningEnabled) { | |
4365 _eden_chunk_index = 0; | |
4366 size_t used = get_eden_used(); | |
4367 size_t capacity = get_eden_capacity(); | |
4368 // Don't start sampling unless we will get sufficiently | |
4369 // many samples. | |
4370 if (used < (capacity/(CMSScheduleRemarkSamplingRatio * 100) | |
4371 * CMSScheduleRemarkEdenPenetration)) { | |
4372 _start_sampling = true; | |
4373 } else { | |
4374 _start_sampling = false; | |
4375 } | |
4376 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
4377 CMSPhaseAccounting pa(this, "preclean", !PrintGCDetails); | |
4378 preclean_work(CMSPrecleanRefLists1, CMSPrecleanSurvivors1); | |
4379 } | |
4380 CMSTokenSync x(true); // is cms thread | |
4381 if (CMSPrecleaningEnabled) { | |
4382 sample_eden(); | |
4383 _collectorState = AbortablePreclean; | |
4384 } else { | |
4385 _collectorState = FinalMarking; | |
4386 } | |
4387 verify_work_stacks_empty(); | |
4388 verify_overflow_empty(); | |
4389 } | |
4390 | |
4391 // Try and schedule the remark such that young gen | |
4392 // occupancy is CMSScheduleRemarkEdenPenetration %. | |
4393 void CMSCollector::abortable_preclean() { | |
4394 check_correct_thread_executing(); | |
4395 assert(CMSPrecleaningEnabled, "Inconsistent control state"); | |
4396 assert(_collectorState == AbortablePreclean, "Inconsistent control state"); | |
4397 | |
4398 // If Eden's current occupancy is below this threshold, | |
4399 // immediately schedule the remark; else preclean | |
4400 // past the next scavenge in an effort to | |
4401 // schedule the pause as described avove. By choosing | |
4402 // CMSScheduleRemarkEdenSizeThreshold >= max eden size | |
4403 // we will never do an actual abortable preclean cycle. | |
4404 if (get_eden_used() > CMSScheduleRemarkEdenSizeThreshold) { | |
4405 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
4406 CMSPhaseAccounting pa(this, "abortable-preclean", !PrintGCDetails); | |
4407 // We need more smarts in the abortable preclean | |
4408 // loop below to deal with cases where allocation | |
4409 // in young gen is very very slow, and our precleaning | |
4410 // is running a losing race against a horde of | |
4411 // mutators intent on flooding us with CMS updates | |
4412 // (dirty cards). | |
4413 // One, admittedly dumb, strategy is to give up | |
4414 // after a certain number of abortable precleaning loops | |
4415 // or after a certain maximum time. We want to make | |
4416 // this smarter in the next iteration. | |
4417 // XXX FIX ME!!! YSR | |
4418 size_t loops = 0, workdone = 0, cumworkdone = 0, waited = 0; | |
4419 while (!(should_abort_preclean() || | |
4420 ConcurrentMarkSweepThread::should_terminate())) { | |
4421 workdone = preclean_work(CMSPrecleanRefLists2, CMSPrecleanSurvivors2); | |
4422 cumworkdone += workdone; | |
4423 loops++; | |
4424 // Voluntarily terminate abortable preclean phase if we have | |
4425 // been at it for too long. | |
4426 if ((CMSMaxAbortablePrecleanLoops != 0) && | |
4427 loops >= CMSMaxAbortablePrecleanLoops) { | |
4428 if (PrintGCDetails) { | |
4429 gclog_or_tty->print(" CMS: abort preclean due to loops "); | |
4430 } | |
4431 break; | |
4432 } | |
4433 if (pa.wallclock_millis() > CMSMaxAbortablePrecleanTime) { | |
4434 if (PrintGCDetails) { | |
4435 gclog_or_tty->print(" CMS: abort preclean due to time "); | |
4436 } | |
4437 break; | |
4438 } | |
4439 // If we are doing little work each iteration, we should | |
4440 // take a short break. | |
4441 if (workdone < CMSAbortablePrecleanMinWorkPerIteration) { | |
4442 // Sleep for some time, waiting for work to accumulate | |
4443 stopTimer(); | |
4444 cmsThread()->wait_on_cms_lock(CMSAbortablePrecleanWaitMillis); | |
4445 startTimer(); | |
4446 waited++; | |
4447 } | |
4448 } | |
4449 if (PrintCMSStatistics > 0) { | |
4450 gclog_or_tty->print(" [%d iterations, %d waits, %d cards)] ", | |
4451 loops, waited, cumworkdone); | |
4452 } | |
4453 } | |
4454 CMSTokenSync x(true); // is cms thread | |
4455 if (_collectorState != Idling) { | |
4456 assert(_collectorState == AbortablePreclean, | |
4457 "Spontaneous state transition?"); | |
4458 _collectorState = FinalMarking; | |
4459 } // Else, a foreground collection completed this CMS cycle. | |
4460 return; | |
4461 } | |
4462 | |
4463 // Respond to an Eden sampling opportunity | |
4464 void CMSCollector::sample_eden() { | |
4465 // Make sure a young gc cannot sneak in between our | |
4466 // reading and recording of a sample. | |
4467 assert(Thread::current()->is_ConcurrentGC_thread(), | |
4468 "Only the cms thread may collect Eden samples"); | |
4469 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
4470 "Should collect samples while holding CMS token"); | |
4471 if (!_start_sampling) { | |
4472 return; | |
4473 } | |
4474 if (_eden_chunk_array) { | |
4475 if (_eden_chunk_index < _eden_chunk_capacity) { | |
4476 _eden_chunk_array[_eden_chunk_index] = *_top_addr; // take sample | |
4477 assert(_eden_chunk_array[_eden_chunk_index] <= *_end_addr, | |
4478 "Unexpected state of Eden"); | |
4479 // We'd like to check that what we just sampled is an oop-start address; | |
4480 // however, we cannot do that here since the object may not yet have been | |
4481 // initialized. So we'll instead do the check when we _use_ this sample | |
4482 // later. | |
4483 if (_eden_chunk_index == 0 || | |
4484 (pointer_delta(_eden_chunk_array[_eden_chunk_index], | |
4485 _eden_chunk_array[_eden_chunk_index-1]) | |
4486 >= CMSSamplingGrain)) { | |
4487 _eden_chunk_index++; // commit sample | |
4488 } | |
4489 } | |
4490 } | |
4491 if ((_collectorState == AbortablePreclean) && !_abort_preclean) { | |
4492 size_t used = get_eden_used(); | |
4493 size_t capacity = get_eden_capacity(); | |
4494 assert(used <= capacity, "Unexpected state of Eden"); | |
4495 if (used > (capacity/100 * CMSScheduleRemarkEdenPenetration)) { | |
4496 _abort_preclean = true; | |
4497 } | |
4498 } | |
4499 } | |
4500 | |
4501 | |
4502 size_t CMSCollector::preclean_work(bool clean_refs, bool clean_survivor) { | |
4503 assert(_collectorState == Precleaning || | |
4504 _collectorState == AbortablePreclean, "incorrect state"); | |
4505 ResourceMark rm; | |
4506 HandleMark hm; | |
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4507 |
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4508 // Precleaning is currently not MT but the reference processor |
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4509 // may be set for MT. Disable it temporarily here. |
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4510 ReferenceProcessor* rp = ref_processor(); |
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4511 ReferenceProcessorMTDiscoveryMutator rp_mut_discovery(rp, false); |
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4512 |
0 | 4513 // Do one pass of scrubbing the discovered reference lists |
4514 // to remove any reference objects with strongly-reachable | |
4515 // referents. | |
4516 if (clean_refs) { | |
4517 CMSPrecleanRefsYieldClosure yield_cl(this); | |
4518 assert(rp->span().equals(_span), "Spans should be equal"); | |
4519 CMSKeepAliveClosure keep_alive(this, _span, &_markBitMap, | |
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4520 &_markStack, true /* preclean */); |
0 | 4521 CMSDrainMarkingStackClosure complete_trace(this, |
452
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4522 _span, &_markBitMap, &_markStack, |
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4523 &keep_alive, true /* preclean */); |
0 | 4524 |
4525 // We don't want this step to interfere with a young | |
4526 // collection because we don't want to take CPU | |
4527 // or memory bandwidth away from the young GC threads | |
4528 // (which may be as many as there are CPUs). | |
4529 // Note that we don't need to protect ourselves from | |
4530 // interference with mutators because they can't | |
4531 // manipulate the discovered reference lists nor affect | |
4532 // the computed reachability of the referents, the | |
4533 // only properties manipulated by the precleaning | |
4534 // of these reference lists. | |
4535 stopTimer(); | |
4536 CMSTokenSyncWithLocks x(true /* is cms thread */, | |
4537 bitMapLock()); | |
4538 startTimer(); | |
4539 sample_eden(); | |
935 | 4540 |
0 | 4541 // The following will yield to allow foreground |
4542 // collection to proceed promptly. XXX YSR: | |
4543 // The code in this method may need further | |
4544 // tweaking for better performance and some restructuring | |
4545 // for cleaner interfaces. | |
4546 rp->preclean_discovered_references( | |
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4547 rp->is_alive_non_header(), &keep_alive, &complete_trace, &yield_cl); |
0 | 4548 } |
4549 | |
4550 if (clean_survivor) { // preclean the active survivor space(s) | |
4551 assert(_young_gen->kind() == Generation::DefNew || | |
4552 _young_gen->kind() == Generation::ParNew || | |
4553 _young_gen->kind() == Generation::ASParNew, | |
4554 "incorrect type for cast"); | |
4555 DefNewGeneration* dng = (DefNewGeneration*)_young_gen; | |
4556 PushAndMarkClosure pam_cl(this, _span, ref_processor(), | |
4557 &_markBitMap, &_modUnionTable, | |
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4558 &_markStack, true /* precleaning phase */); |
0 | 4559 stopTimer(); |
4560 CMSTokenSyncWithLocks ts(true /* is cms thread */, | |
4561 bitMapLock()); | |
4562 startTimer(); | |
4563 unsigned int before_count = | |
4564 GenCollectedHeap::heap()->total_collections(); | |
4565 SurvivorSpacePrecleanClosure | |
4566 sss_cl(this, _span, &_markBitMap, &_markStack, | |
4567 &pam_cl, before_count, CMSYield); | |
4568 dng->from()->object_iterate_careful(&sss_cl); | |
4569 dng->to()->object_iterate_careful(&sss_cl); | |
4570 } | |
4571 MarkRefsIntoAndScanClosure | |
4572 mrias_cl(_span, ref_processor(), &_markBitMap, &_modUnionTable, | |
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4573 &_markStack, this, CMSYield, |
0 | 4574 true /* precleaning phase */); |
4575 // CAUTION: The following closure has persistent state that may need to | |
4576 // be reset upon a decrease in the sequence of addresses it | |
4577 // processes. | |
4578 ScanMarkedObjectsAgainCarefullyClosure | |
4579 smoac_cl(this, _span, | |
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4580 &_markBitMap, &_markStack, &mrias_cl, CMSYield); |
0 | 4581 |
4582 // Preclean dirty cards in ModUnionTable and CardTable using | |
4583 // appropriate convergence criterion; | |
4584 // repeat CMSPrecleanIter times unless we find that | |
4585 // we are losing. | |
4586 assert(CMSPrecleanIter < 10, "CMSPrecleanIter is too large"); | |
4587 assert(CMSPrecleanNumerator < CMSPrecleanDenominator, | |
4588 "Bad convergence multiplier"); | |
4589 assert(CMSPrecleanThreshold >= 100, | |
4590 "Unreasonably low CMSPrecleanThreshold"); | |
4591 | |
4592 size_t numIter, cumNumCards, lastNumCards, curNumCards; | |
4593 for (numIter = 0, cumNumCards = lastNumCards = curNumCards = 0; | |
4594 numIter < CMSPrecleanIter; | |
4595 numIter++, lastNumCards = curNumCards, cumNumCards += curNumCards) { | |
4596 curNumCards = preclean_mod_union_table(_cmsGen, &smoac_cl); | |
4597 if (Verbose && PrintGCDetails) { | |
4598 gclog_or_tty->print(" (modUnionTable: %d cards)", curNumCards); | |
4599 } | |
4600 // Either there are very few dirty cards, so re-mark | |
4601 // pause will be small anyway, or our pre-cleaning isn't | |
4602 // that much faster than the rate at which cards are being | |
4603 // dirtied, so we might as well stop and re-mark since | |
4604 // precleaning won't improve our re-mark time by much. | |
4605 if (curNumCards <= CMSPrecleanThreshold || | |
4606 (numIter > 0 && | |
4607 (curNumCards * CMSPrecleanDenominator > | |
4608 lastNumCards * CMSPrecleanNumerator))) { | |
4609 numIter++; | |
4610 cumNumCards += curNumCards; | |
4611 break; | |
4612 } | |
4613 } | |
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4614 |
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4615 preclean_klasses(&mrias_cl, _cmsGen->freelistLock()); |
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4616 |
0 | 4617 curNumCards = preclean_card_table(_cmsGen, &smoac_cl); |
4618 cumNumCards += curNumCards; | |
4619 if (PrintGCDetails && PrintCMSStatistics != 0) { | |
4620 gclog_or_tty->print_cr(" (cardTable: %d cards, re-scanned %d cards, %d iterations)", | |
4621 curNumCards, cumNumCards, numIter); | |
4622 } | |
4623 return cumNumCards; // as a measure of useful work done | |
4624 } | |
4625 | |
4626 // PRECLEANING NOTES: | |
4627 // Precleaning involves: | |
4628 // . reading the bits of the modUnionTable and clearing the set bits. | |
4629 // . For the cards corresponding to the set bits, we scan the | |
4630 // objects on those cards. This means we need the free_list_lock | |
4631 // so that we can safely iterate over the CMS space when scanning | |
4632 // for oops. | |
4633 // . When we scan the objects, we'll be both reading and setting | |
4634 // marks in the marking bit map, so we'll need the marking bit map. | |
4635 // . For protecting _collector_state transitions, we take the CGC_lock. | |
4636 // Note that any races in the reading of of card table entries by the | |
4637 // CMS thread on the one hand and the clearing of those entries by the | |
4638 // VM thread or the setting of those entries by the mutator threads on the | |
4639 // other are quite benign. However, for efficiency it makes sense to keep | |
4640 // the VM thread from racing with the CMS thread while the latter is | |
4641 // dirty card info to the modUnionTable. We therefore also use the | |
4642 // CGC_lock to protect the reading of the card table and the mod union | |
4643 // table by the CM thread. | |
4644 // . We run concurrently with mutator updates, so scanning | |
4645 // needs to be done carefully -- we should not try to scan | |
4646 // potentially uninitialized objects. | |
4647 // | |
4648 // Locking strategy: While holding the CGC_lock, we scan over and | |
4649 // reset a maximal dirty range of the mod union / card tables, then lock | |
4650 // the free_list_lock and bitmap lock to do a full marking, then | |
4651 // release these locks; and repeat the cycle. This allows for a | |
4652 // certain amount of fairness in the sharing of these locks between | |
4653 // the CMS collector on the one hand, and the VM thread and the | |
4654 // mutators on the other. | |
4655 | |
4656 // NOTE: preclean_mod_union_table() and preclean_card_table() | |
4657 // further below are largely identical; if you need to modify | |
4658 // one of these methods, please check the other method too. | |
4659 | |
4660 size_t CMSCollector::preclean_mod_union_table( | |
4661 ConcurrentMarkSweepGeneration* gen, | |
4662 ScanMarkedObjectsAgainCarefullyClosure* cl) { | |
4663 verify_work_stacks_empty(); | |
4664 verify_overflow_empty(); | |
4665 | |
4666 // strategy: starting with the first card, accumulate contiguous | |
4667 // ranges of dirty cards; clear these cards, then scan the region | |
4668 // covered by these cards. | |
4669 | |
4670 // Since all of the MUT is committed ahead, we can just use | |
4671 // that, in case the generations expand while we are precleaning. | |
4672 // It might also be fine to just use the committed part of the | |
4673 // generation, but we might potentially miss cards when the | |
4674 // generation is rapidly expanding while we are in the midst | |
4675 // of precleaning. | |
4676 HeapWord* startAddr = gen->reserved().start(); | |
4677 HeapWord* endAddr = gen->reserved().end(); | |
4678 | |
4679 cl->setFreelistLock(gen->freelistLock()); // needed for yielding | |
4680 | |
4681 size_t numDirtyCards, cumNumDirtyCards; | |
4682 HeapWord *nextAddr, *lastAddr; | |
4683 for (cumNumDirtyCards = numDirtyCards = 0, | |
4684 nextAddr = lastAddr = startAddr; | |
4685 nextAddr < endAddr; | |
4686 nextAddr = lastAddr, cumNumDirtyCards += numDirtyCards) { | |
4687 | |
4688 ResourceMark rm; | |
4689 HandleMark hm; | |
4690 | |
4691 MemRegion dirtyRegion; | |
4692 { | |
4693 stopTimer(); | |
935 | 4694 // Potential yield point |
0 | 4695 CMSTokenSync ts(true); |
4696 startTimer(); | |
4697 sample_eden(); | |
4698 // Get dirty region starting at nextOffset (inclusive), | |
4699 // simultaneously clearing it. | |
4700 dirtyRegion = | |
4701 _modUnionTable.getAndClearMarkedRegion(nextAddr, endAddr); | |
4702 assert(dirtyRegion.start() >= nextAddr, | |
4703 "returned region inconsistent?"); | |
4704 } | |
4705 // Remember where the next search should begin. | |
4706 // The returned region (if non-empty) is a right open interval, | |
4707 // so lastOffset is obtained from the right end of that | |
4708 // interval. | |
4709 lastAddr = dirtyRegion.end(); | |
4710 // Should do something more transparent and less hacky XXX | |
4711 numDirtyCards = | |
4712 _modUnionTable.heapWordDiffToOffsetDiff(dirtyRegion.word_size()); | |
4713 | |
4714 // We'll scan the cards in the dirty region (with periodic | |
4715 // yields for foreground GC as needed). | |
4716 if (!dirtyRegion.is_empty()) { | |
4717 assert(numDirtyCards > 0, "consistency check"); | |
4718 HeapWord* stop_point = NULL; | |
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4719 stopTimer(); |
935 | 4720 // Potential yield point |
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4721 CMSTokenSyncWithLocks ts(true, gen->freelistLock(), |
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4722 bitMapLock()); |
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4723 startTimer(); |
0 | 4724 { |
4725 verify_work_stacks_empty(); | |
4726 verify_overflow_empty(); | |
4727 sample_eden(); | |
4728 stop_point = | |
4729 gen->cmsSpace()->object_iterate_careful_m(dirtyRegion, cl); | |
4730 } | |
4731 if (stop_point != NULL) { | |
4732 // The careful iteration stopped early either because it found an | |
4733 // uninitialized object, or because we were in the midst of an | |
4734 // "abortable preclean", which should now be aborted. Redirty | |
4735 // the bits corresponding to the partially-scanned or unscanned | |
4736 // cards. We'll either restart at the next block boundary or | |
4737 // abort the preclean. | |
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4738 assert((_collectorState == AbortablePreclean && should_abort_preclean()), |
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4739 "Should only be AbortablePreclean."); |
0 | 4740 _modUnionTable.mark_range(MemRegion(stop_point, dirtyRegion.end())); |
4741 if (should_abort_preclean()) { | |
4742 break; // out of preclean loop | |
4743 } else { | |
4744 // Compute the next address at which preclean should pick up; | |
4745 // might need bitMapLock in order to read P-bits. | |
4746 lastAddr = next_card_start_after_block(stop_point); | |
4747 } | |
4748 } | |
4749 } else { | |
4750 assert(lastAddr == endAddr, "consistency check"); | |
4751 assert(numDirtyCards == 0, "consistency check"); | |
4752 break; | |
4753 } | |
4754 } | |
4755 verify_work_stacks_empty(); | |
4756 verify_overflow_empty(); | |
4757 return cumNumDirtyCards; | |
4758 } | |
4759 | |
4760 // NOTE: preclean_mod_union_table() above and preclean_card_table() | |
4761 // below are largely identical; if you need to modify | |
4762 // one of these methods, please check the other method too. | |
4763 | |
4764 size_t CMSCollector::preclean_card_table(ConcurrentMarkSweepGeneration* gen, | |
4765 ScanMarkedObjectsAgainCarefullyClosure* cl) { | |
4766 // strategy: it's similar to precleamModUnionTable above, in that | |
4767 // we accumulate contiguous ranges of dirty cards, mark these cards | |
4768 // precleaned, then scan the region covered by these cards. | |
4769 HeapWord* endAddr = (HeapWord*)(gen->_virtual_space.high()); | |
4770 HeapWord* startAddr = (HeapWord*)(gen->_virtual_space.low()); | |
4771 | |
4772 cl->setFreelistLock(gen->freelistLock()); // needed for yielding | |
4773 | |
4774 size_t numDirtyCards, cumNumDirtyCards; | |
4775 HeapWord *lastAddr, *nextAddr; | |
4776 | |
4777 for (cumNumDirtyCards = numDirtyCards = 0, | |
4778 nextAddr = lastAddr = startAddr; | |
4779 nextAddr < endAddr; | |
4780 nextAddr = lastAddr, cumNumDirtyCards += numDirtyCards) { | |
4781 | |
4782 ResourceMark rm; | |
4783 HandleMark hm; | |
4784 | |
4785 MemRegion dirtyRegion; | |
4786 { | |
4787 // See comments in "Precleaning notes" above on why we | |
4788 // do this locking. XXX Could the locking overheads be | |
4789 // too high when dirty cards are sparse? [I don't think so.] | |
4790 stopTimer(); | |
4791 CMSTokenSync x(true); // is cms thread | |
4792 startTimer(); | |
4793 sample_eden(); | |
4794 // Get and clear dirty region from card table | |
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4795 dirtyRegion = _ct->ct_bs()->dirty_card_range_after_reset( |
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4796 MemRegion(nextAddr, endAddr), |
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4797 true, |
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4798 CardTableModRefBS::precleaned_card_val()); |
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4799 |
0 | 4800 assert(dirtyRegion.start() >= nextAddr, |
4801 "returned region inconsistent?"); | |
4802 } | |
4803 lastAddr = dirtyRegion.end(); | |
4804 numDirtyCards = | |
4805 dirtyRegion.word_size()/CardTableModRefBS::card_size_in_words; | |
4806 | |
4807 if (!dirtyRegion.is_empty()) { | |
4808 stopTimer(); | |
4809 CMSTokenSyncWithLocks ts(true, gen->freelistLock(), bitMapLock()); | |
4810 startTimer(); | |
4811 sample_eden(); | |
4812 verify_work_stacks_empty(); | |
4813 verify_overflow_empty(); | |
4814 HeapWord* stop_point = | |
4815 gen->cmsSpace()->object_iterate_careful_m(dirtyRegion, cl); | |
4816 if (stop_point != NULL) { | |
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4817 assert((_collectorState == AbortablePreclean && should_abort_preclean()), |
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4818 "Should only be AbortablePreclean."); |
0 | 4819 _ct->ct_bs()->invalidate(MemRegion(stop_point, dirtyRegion.end())); |
4820 if (should_abort_preclean()) { | |
4821 break; // out of preclean loop | |
4822 } else { | |
4823 // Compute the next address at which preclean should pick up. | |
4824 lastAddr = next_card_start_after_block(stop_point); | |
4825 } | |
4826 } | |
4827 } else { | |
4828 break; | |
4829 } | |
4830 } | |
4831 verify_work_stacks_empty(); | |
4832 verify_overflow_empty(); | |
4833 return cumNumDirtyCards; | |
4834 } | |
4835 | |
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4836 class PrecleanKlassClosure : public KlassClosure { |
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4837 CMKlassClosure _cm_klass_closure; |
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4838 public: |
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4839 PrecleanKlassClosure(OopClosure* oop_closure) : _cm_klass_closure(oop_closure) {} |
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4840 void do_klass(Klass* k) { |
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4841 if (k->has_accumulated_modified_oops()) { |
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4842 k->clear_accumulated_modified_oops(); |
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4843 |
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4844 _cm_klass_closure.do_klass(k); |
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4845 } |
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4846 } |
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4847 }; |
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4848 |
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4849 // The freelist lock is needed to prevent asserts, is it really needed? |
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4850 void CMSCollector::preclean_klasses(MarkRefsIntoAndScanClosure* cl, Mutex* freelistLock) { |
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4851 |
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4852 cl->set_freelistLock(freelistLock); |
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4853 |
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4854 CMSTokenSyncWithLocks ts(true, freelistLock, bitMapLock()); |
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4855 |
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4856 // SSS: Add equivalent to ScanMarkedObjectsAgainCarefullyClosure::do_yield_check and should_abort_preclean? |
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4857 // SSS: We should probably check if precleaning should be aborted, at suitable intervals? |
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4858 PrecleanKlassClosure preclean_klass_closure(cl); |
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4859 ClassLoaderDataGraph::classes_do(&preclean_klass_closure); |
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4860 |
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4861 verify_work_stacks_empty(); |
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4862 verify_overflow_empty(); |
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4863 } |
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4864 |
0 | 4865 void CMSCollector::checkpointRootsFinal(bool asynch, |
4866 bool clear_all_soft_refs, bool init_mark_was_synchronous) { | |
4867 assert(_collectorState == FinalMarking, "incorrect state transition?"); | |
4868 check_correct_thread_executing(); | |
4869 // world is stopped at this checkpoint | |
4870 assert(SafepointSynchronize::is_at_safepoint(), | |
4871 "world should be stopped"); | |
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4872 TraceCMSMemoryManagerStats tms(_collectorState,GenCollectedHeap::heap()->gc_cause()); |
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4873 |
0 | 4874 verify_work_stacks_empty(); |
4875 verify_overflow_empty(); | |
4876 | |
4877 SpecializationStats::clear(); | |
4878 if (PrintGCDetails) { | |
4879 gclog_or_tty->print("[YG occupancy: "SIZE_FORMAT" K ("SIZE_FORMAT" K)]", | |
4880 _young_gen->used() / K, | |
4881 _young_gen->capacity() / K); | |
4882 } | |
4883 if (asynch) { | |
4884 if (CMSScavengeBeforeRemark) { | |
4885 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
4886 // Temporarily set flag to false, GCH->do_collection will | |
4887 // expect it to be false and set to true | |
4888 FlagSetting fl(gch->_is_gc_active, false); | |
4889 NOT_PRODUCT(TraceTime t("Scavenge-Before-Remark", | |
4890 PrintGCDetails && Verbose, true, gclog_or_tty);) | |
4891 int level = _cmsGen->level() - 1; | |
4892 if (level >= 0) { | |
4893 gch->do_collection(true, // full (i.e. force, see below) | |
4894 false, // !clear_all_soft_refs | |
4895 0, // size | |
4896 false, // is_tlab | |
4897 level // max_level | |
4898 ); | |
4899 } | |
4900 } | |
4901 FreelistLocker x(this); | |
4902 MutexLockerEx y(bitMapLock(), | |
4903 Mutex::_no_safepoint_check_flag); | |
4904 assert(!init_mark_was_synchronous, "but that's impossible!"); | |
4905 checkpointRootsFinalWork(asynch, clear_all_soft_refs, false); | |
4906 } else { | |
4907 // already have all the locks | |
4908 checkpointRootsFinalWork(asynch, clear_all_soft_refs, | |
4909 init_mark_was_synchronous); | |
4910 } | |
4911 verify_work_stacks_empty(); | |
4912 verify_overflow_empty(); | |
4913 SpecializationStats::print(); | |
4914 } | |
4915 | |
4916 void CMSCollector::checkpointRootsFinalWork(bool asynch, | |
4917 bool clear_all_soft_refs, bool init_mark_was_synchronous) { | |
4918 | |
4919 NOT_PRODUCT(TraceTime tr("checkpointRootsFinalWork", PrintGCDetails, false, gclog_or_tty);) | |
4920 | |
4921 assert(haveFreelistLocks(), "must have free list locks"); | |
4922 assert_lock_strong(bitMapLock()); | |
4923 | |
4924 if (UseAdaptiveSizePolicy) { | |
4925 size_policy()->checkpoint_roots_final_begin(); | |
4926 } | |
4927 | |
4928 ResourceMark rm; | |
4929 HandleMark hm; | |
4930 | |
4931 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
4932 | |
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4933 if (should_unload_classes()) { |
0 | 4934 CodeCache::gc_prologue(); |
4935 } | |
4936 assert(haveFreelistLocks(), "must have free list locks"); | |
4937 assert_lock_strong(bitMapLock()); | |
4938 | |
4939 if (!init_mark_was_synchronous) { | |
4940 // We might assume that we need not fill TLAB's when | |
4941 // CMSScavengeBeforeRemark is set, because we may have just done | |
4942 // a scavenge which would have filled all TLAB's -- and besides | |
4943 // Eden would be empty. This however may not always be the case -- | |
4944 // for instance although we asked for a scavenge, it may not have | |
4945 // happened because of a JNI critical section. We probably need | |
4946 // a policy for deciding whether we can in that case wait until | |
4947 // the critical section releases and then do the remark following | |
4948 // the scavenge, and skip it here. In the absence of that policy, | |
4949 // or of an indication of whether the scavenge did indeed occur, | |
4950 // we cannot rely on TLAB's having been filled and must do | |
4951 // so here just in case a scavenge did not happen. | |
4952 gch->ensure_parsability(false); // fill TLAB's, but no need to retire them | |
4953 // Update the saved marks which may affect the root scans. | |
4954 gch->save_marks(); | |
4955 | |
4956 { | |
4957 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact;) | |
4958 | |
4959 // Note on the role of the mod union table: | |
4960 // Since the marker in "markFromRoots" marks concurrently with | |
4961 // mutators, it is possible for some reachable objects not to have been | |
4962 // scanned. For instance, an only reference to an object A was | |
4963 // placed in object B after the marker scanned B. Unless B is rescanned, | |
4964 // A would be collected. Such updates to references in marked objects | |
4965 // are detected via the mod union table which is the set of all cards | |
4966 // dirtied since the first checkpoint in this GC cycle and prior to | |
4967 // the most recent young generation GC, minus those cleaned up by the | |
4968 // concurrent precleaning. | |
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4969 if (CMSParallelRemarkEnabled && CollectedHeap::use_parallel_gc_threads()) { |
0 | 4970 TraceTime t("Rescan (parallel) ", PrintGCDetails, false, gclog_or_tty); |
4971 do_remark_parallel(); | |
4972 } else { | |
4973 TraceTime t("Rescan (non-parallel) ", PrintGCDetails, false, | |
4974 gclog_or_tty); | |
4975 do_remark_non_parallel(); | |
4976 } | |
4977 } | |
4978 } else { | |
4979 assert(!asynch, "Can't have init_mark_was_synchronous in asynch mode"); | |
4980 // The initial mark was stop-world, so there's no rescanning to | |
4981 // do; go straight on to the next step below. | |
4982 } | |
4983 verify_work_stacks_empty(); | |
4984 verify_overflow_empty(); | |
4985 | |
4986 { | |
4987 NOT_PRODUCT(TraceTime ts("refProcessingWork", PrintGCDetails, false, gclog_or_tty);) | |
4988 refProcessingWork(asynch, clear_all_soft_refs); | |
4989 } | |
4990 verify_work_stacks_empty(); | |
4991 verify_overflow_empty(); | |
4992 | |
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4993 if (should_unload_classes()) { |
0 | 4994 CodeCache::gc_epilogue(); |
4995 } | |
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4996 JvmtiExport::gc_epilogue(); |
0 | 4997 |
4998 // If we encountered any (marking stack / work queue) overflow | |
4999 // events during the current CMS cycle, take appropriate | |
5000 // remedial measures, where possible, so as to try and avoid | |
5001 // recurrence of that condition. | |
5002 assert(_markStack.isEmpty(), "No grey objects"); | |
5003 size_t ser_ovflw = _ser_pmc_remark_ovflw + _ser_pmc_preclean_ovflw + | |
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5004 _ser_kac_ovflw + _ser_kac_preclean_ovflw; |
0 | 5005 if (ser_ovflw > 0) { |
5006 if (PrintCMSStatistics != 0) { | |
5007 gclog_or_tty->print_cr("Marking stack overflow (benign) " | |
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5008 "(pmc_pc="SIZE_FORMAT", pmc_rm="SIZE_FORMAT", kac="SIZE_FORMAT |
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5009 ", kac_preclean="SIZE_FORMAT")", |
0 | 5010 _ser_pmc_preclean_ovflw, _ser_pmc_remark_ovflw, |
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5011 _ser_kac_ovflw, _ser_kac_preclean_ovflw); |
0 | 5012 } |
5013 _markStack.expand(); | |
5014 _ser_pmc_remark_ovflw = 0; | |
5015 _ser_pmc_preclean_ovflw = 0; | |
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5016 _ser_kac_preclean_ovflw = 0; |
0 | 5017 _ser_kac_ovflw = 0; |
5018 } | |
5019 if (_par_pmc_remark_ovflw > 0 || _par_kac_ovflw > 0) { | |
5020 if (PrintCMSStatistics != 0) { | |
5021 gclog_or_tty->print_cr("Work queue overflow (benign) " | |
5022 "(pmc_rm="SIZE_FORMAT", kac="SIZE_FORMAT")", | |
5023 _par_pmc_remark_ovflw, _par_kac_ovflw); | |
5024 } | |
5025 _par_pmc_remark_ovflw = 0; | |
5026 _par_kac_ovflw = 0; | |
5027 } | |
5028 if (PrintCMSStatistics != 0) { | |
5029 if (_markStack._hit_limit > 0) { | |
5030 gclog_or_tty->print_cr(" (benign) Hit max stack size limit ("SIZE_FORMAT")", | |
5031 _markStack._hit_limit); | |
5032 } | |
5033 if (_markStack._failed_double > 0) { | |
5034 gclog_or_tty->print_cr(" (benign) Failed stack doubling ("SIZE_FORMAT")," | |
5035 " current capacity "SIZE_FORMAT, | |
5036 _markStack._failed_double, | |
5037 _markStack.capacity()); | |
5038 } | |
5039 } | |
5040 _markStack._hit_limit = 0; | |
5041 _markStack._failed_double = 0; | |
5042 | |
5043 if ((VerifyAfterGC || VerifyDuringGC) && | |
5044 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
5045 verify_after_remark(); | |
5046 } | |
5047 | |
5048 // Change under the freelistLocks. | |
5049 _collectorState = Sweeping; | |
5050 // Call isAllClear() under bitMapLock | |
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5051 assert(_modUnionTable.isAllClear(), |
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5052 "Should be clear by end of the final marking"); |
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5053 assert(_ct->klass_rem_set()->mod_union_is_clear(), |
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5054 "Should be clear by end of the final marking"); |
0 | 5055 if (UseAdaptiveSizePolicy) { |
5056 size_policy()->checkpoint_roots_final_end(gch->gc_cause()); | |
5057 } | |
5058 } | |
5059 | |
5060 // Parallel remark task | |
5061 class CMSParRemarkTask: public AbstractGangTask { | |
5062 CMSCollector* _collector; | |
5063 int _n_workers; | |
5064 CompactibleFreeListSpace* _cms_space; | |
5065 | |
5066 // The per-thread work queues, available here for stealing. | |
5067 OopTaskQueueSet* _task_queues; | |
5068 ParallelTaskTerminator _term; | |
5069 | |
5070 public: | |
4095
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5071 // A value of 0 passed to n_workers will cause the number of |
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5072 // workers to be taken from the active workers in the work gang. |
0 | 5073 CMSParRemarkTask(CMSCollector* collector, |
5074 CompactibleFreeListSpace* cms_space, | |
1833
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5075 int n_workers, FlexibleWorkGang* workers, |
0 | 5076 OopTaskQueueSet* task_queues): |
5077 AbstractGangTask("Rescan roots and grey objects in parallel"), | |
5078 _collector(collector), | |
6725
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5079 _cms_space(cms_space), |
0 | 5080 _n_workers(n_workers), |
5081 _task_queues(task_queues), | |
1833
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5082 _term(n_workers, task_queues) { } |
0 | 5083 |
5084 OopTaskQueueSet* task_queues() { return _task_queues; } | |
5085 | |
5086 OopTaskQueue* work_queue(int i) { return task_queues()->queue(i); } | |
5087 | |
5088 ParallelTaskTerminator* terminator() { return &_term; } | |
1833
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5089 int n_workers() { return _n_workers; } |
0 | 5090 |
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5091 void work(uint worker_id); |
0 | 5092 |
5093 private: | |
5094 // Work method in support of parallel rescan ... of young gen spaces | |
5095 void do_young_space_rescan(int i, Par_MarkRefsIntoAndScanClosure* cl, | |
5096 ContiguousSpace* space, | |
5097 HeapWord** chunk_array, size_t chunk_top); | |
5098 | |
5099 // ... of dirty cards in old space | |
5100 void do_dirty_card_rescan_tasks(CompactibleFreeListSpace* sp, int i, | |
5101 Par_MarkRefsIntoAndScanClosure* cl); | |
5102 | |
5103 // ... work stealing for the above | |
5104 void do_work_steal(int i, Par_MarkRefsIntoAndScanClosure* cl, int* seed); | |
5105 }; | |
5106 | |
6725
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5107 class RemarkKlassClosure : public KlassClosure { |
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5108 CMKlassClosure _cm_klass_closure; |
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5109 public: |
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5110 RemarkKlassClosure(OopClosure* oop_closure) : _cm_klass_closure(oop_closure) {} |
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5111 void do_klass(Klass* k) { |
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5112 // Check if we have modified any oops in the Klass during the concurrent marking. |
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5113 if (k->has_accumulated_modified_oops()) { |
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5114 k->clear_accumulated_modified_oops(); |
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5115 |
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5116 // We could have transfered the current modified marks to the accumulated marks, |
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5117 // like we do with the Card Table to Mod Union Table. But it's not really necessary. |
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5118 } else if (k->has_modified_oops()) { |
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5119 // Don't clear anything, this info is needed by the next young collection. |
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5120 } else { |
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5121 // No modified oops in the Klass. |
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5122 return; |
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5123 } |
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5124 |
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5125 // The klass has modified fields, need to scan the klass. |
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5126 _cm_klass_closure.do_klass(k); |
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5127 } |
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5128 }; |
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5129 |
1833
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5130 // work_queue(i) is passed to the closure |
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5131 // Par_MarkRefsIntoAndScanClosure. The "i" parameter |
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5132 // also is passed to do_dirty_card_rescan_tasks() and to |
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5133 // do_work_steal() to select the i-th task_queue. |
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5134 |
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5135 void CMSParRemarkTask::work(uint worker_id) { |
0 | 5136 elapsedTimer _timer; |
5137 ResourceMark rm; | |
5138 HandleMark hm; | |
5139 | |
5140 // ---------- rescan from roots -------------- | |
5141 _timer.start(); | |
5142 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
5143 Par_MarkRefsIntoAndScanClosure par_mrias_cl(_collector, | |
5144 _collector->_span, _collector->ref_processor(), | |
5145 &(_collector->_markBitMap), | |
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5146 work_queue(worker_id)); |
0 | 5147 |
5148 // Rescan young gen roots first since these are likely | |
5149 // coarsely partitioned and may, on that account, constitute | |
5150 // the critical path; thus, it's best to start off that | |
5151 // work first. | |
5152 // ---------- young gen roots -------------- | |
5153 { | |
5154 DefNewGeneration* dng = _collector->_young_gen->as_DefNewGeneration(); | |
5155 EdenSpace* eden_space = dng->eden(); | |
5156 ContiguousSpace* from_space = dng->from(); | |
5157 ContiguousSpace* to_space = dng->to(); | |
5158 | |
5159 HeapWord** eca = _collector->_eden_chunk_array; | |
5160 size_t ect = _collector->_eden_chunk_index; | |
5161 HeapWord** sca = _collector->_survivor_chunk_array; | |
5162 size_t sct = _collector->_survivor_chunk_index; | |
5163 | |
5164 assert(ect <= _collector->_eden_chunk_capacity, "out of bounds"); | |
5165 assert(sct <= _collector->_survivor_chunk_capacity, "out of bounds"); | |
5166 | |
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5167 do_young_space_rescan(worker_id, &par_mrias_cl, to_space, NULL, 0); |
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5168 do_young_space_rescan(worker_id, &par_mrias_cl, from_space, sca, sct); |
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5169 do_young_space_rescan(worker_id, &par_mrias_cl, eden_space, eca, ect); |
0 | 5170 |
5171 _timer.stop(); | |
5172 if (PrintCMSStatistics != 0) { | |
5173 gclog_or_tty->print_cr( | |
5174 "Finished young gen rescan work in %dth thread: %3.3f sec", | |
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5175 worker_id, _timer.seconds()); |
0 | 5176 } |
5177 } | |
5178 | |
5179 // ---------- remaining roots -------------- | |
5180 _timer.reset(); | |
5181 _timer.start(); | |
5182 gch->gen_process_strong_roots(_collector->_cmsGen->level(), | |
5183 false, // yg was scanned above | |
989
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5184 false, // this is parallel code |
6725
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5185 false, // not scavenging |
0 | 5186 SharedHeap::ScanningOption(_collector->CMSCollector::roots_scanning_options()), |
989
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5187 &par_mrias_cl, |
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5188 true, // walk all of code cache if (so & SO_CodeCache) |
6725
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5189 NULL, |
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5190 NULL); // The dirty klasses will be handled below |
989
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5191 assert(_collector->should_unload_classes() |
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5192 || (_collector->CMSCollector::roots_scanning_options() & SharedHeap::SO_CodeCache), |
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5193 "if we didn't scan the code cache, we have to be ready to drop nmethods with expired weak oops"); |
0 | 5194 _timer.stop(); |
5195 if (PrintCMSStatistics != 0) { | |
5196 gclog_or_tty->print_cr( | |
5197 "Finished remaining root rescan work in %dth thread: %3.3f sec", | |
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5198 worker_id, _timer.seconds()); |
0 | 5199 } |
5200 | |
6725
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5201 // ---------- unhandled CLD scanning ---------- |
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5202 if (worker_id == 0) { // Single threaded at the moment. |
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5203 _timer.reset(); |
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5204 _timer.start(); |
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5205 |
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5206 // Scan all new class loader data objects and new dependencies that were |
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5207 // introduced during concurrent marking. |
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5208 ResourceMark rm; |
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5209 GrowableArray<ClassLoaderData*>* array = ClassLoaderDataGraph::new_clds(); |
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5210 for (int i = 0; i < array->length(); i++) { |
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5211 par_mrias_cl.do_class_loader_data(array->at(i)); |
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5212 } |
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5213 |
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5214 // We don't need to keep track of new CLDs anymore. |
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5215 ClassLoaderDataGraph::remember_new_clds(false); |
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5216 |
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5217 _timer.stop(); |
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5218 if (PrintCMSStatistics != 0) { |
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5219 gclog_or_tty->print_cr( |
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5220 "Finished unhandled CLD scanning work in %dth thread: %3.3f sec", |
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5221 worker_id, _timer.seconds()); |
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5222 } |
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5223 } |
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5224 |
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5225 // ---------- dirty klass scanning ---------- |
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5226 if (worker_id == 0) { // Single threaded at the moment. |
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5227 _timer.reset(); |
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5228 _timer.start(); |
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5229 |
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5230 // Scan all classes that was dirtied during the concurrent marking phase. |
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5231 RemarkKlassClosure remark_klass_closure(&par_mrias_cl); |
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5232 ClassLoaderDataGraph::classes_do(&remark_klass_closure); |
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5233 |
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5234 _timer.stop(); |
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5235 if (PrintCMSStatistics != 0) { |
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5236 gclog_or_tty->print_cr( |
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5237 "Finished dirty klass scanning work in %dth thread: %3.3f sec", |
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5238 worker_id, _timer.seconds()); |
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5239 } |
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5240 } |
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5241 |
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5242 // We might have added oops to ClassLoaderData::_handles during the |
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5243 // concurrent marking phase. These oops point to newly allocated objects |
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5244 // that are guaranteed to be kept alive. Either by the direct allocation |
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5245 // code, or when the young collector processes the strong roots. Hence, |
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5246 // we don't have to revisit the _handles block during the remark phase. |
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5247 |
0 | 5248 // ---------- rescan dirty cards ------------ |
5249 _timer.reset(); | |
5250 _timer.start(); | |
5251 | |
5252 // Do the rescan tasks for each of the two spaces | |
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5253 // (cms_space) in turn. |
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5254 // "worker_id" is passed to select the task_queue for "worker_id" |
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5255 do_dirty_card_rescan_tasks(_cms_space, worker_id, &par_mrias_cl); |
0 | 5256 _timer.stop(); |
5257 if (PrintCMSStatistics != 0) { | |
5258 gclog_or_tty->print_cr( | |
5259 "Finished dirty card rescan work in %dth thread: %3.3f sec", | |
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5260 worker_id, _timer.seconds()); |
0 | 5261 } |
5262 | |
5263 // ---------- steal work from other threads ... | |
5264 // ---------- ... and drain overflow list. | |
5265 _timer.reset(); | |
5266 _timer.start(); | |
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5267 do_work_steal(worker_id, &par_mrias_cl, _collector->hash_seed(worker_id)); |
0 | 5268 _timer.stop(); |
5269 if (PrintCMSStatistics != 0) { | |
5270 gclog_or_tty->print_cr( | |
5271 "Finished work stealing in %dth thread: %3.3f sec", | |
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5272 worker_id, _timer.seconds()); |
0 | 5273 } |
5274 } | |
5275 | |
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5276 // Note that parameter "i" is not used. |
0 | 5277 void |
5278 CMSParRemarkTask::do_young_space_rescan(int i, | |
5279 Par_MarkRefsIntoAndScanClosure* cl, ContiguousSpace* space, | |
5280 HeapWord** chunk_array, size_t chunk_top) { | |
5281 // Until all tasks completed: | |
5282 // . claim an unclaimed task | |
5283 // . compute region boundaries corresponding to task claimed | |
5284 // using chunk_array | |
5285 // . par_oop_iterate(cl) over that region | |
5286 | |
5287 ResourceMark rm; | |
5288 HandleMark hm; | |
5289 | |
5290 SequentialSubTasksDone* pst = space->par_seq_tasks(); | |
5291 assert(pst->valid(), "Uninitialized use?"); | |
5292 | |
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5293 uint nth_task = 0; |
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5294 uint n_tasks = pst->n_tasks(); |
0 | 5295 |
5296 HeapWord *start, *end; | |
5297 while (!pst->is_task_claimed(/* reference */ nth_task)) { | |
5298 // We claimed task # nth_task; compute its boundaries. | |
5299 if (chunk_top == 0) { // no samples were taken | |
5300 assert(nth_task == 0 && n_tasks == 1, "Can have only 1 EdenSpace task"); | |
5301 start = space->bottom(); | |
5302 end = space->top(); | |
5303 } else if (nth_task == 0) { | |
5304 start = space->bottom(); | |
5305 end = chunk_array[nth_task]; | |
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5306 } else if (nth_task < (uint)chunk_top) { |
0 | 5307 assert(nth_task >= 1, "Control point invariant"); |
5308 start = chunk_array[nth_task - 1]; | |
5309 end = chunk_array[nth_task]; | |
5310 } else { | |
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5311 assert(nth_task == (uint)chunk_top, "Control point invariant"); |
0 | 5312 start = chunk_array[chunk_top - 1]; |
5313 end = space->top(); | |
5314 } | |
5315 MemRegion mr(start, end); | |
5316 // Verify that mr is in space | |
5317 assert(mr.is_empty() || space->used_region().contains(mr), | |
5318 "Should be in space"); | |
5319 // Verify that "start" is an object boundary | |
5320 assert(mr.is_empty() || oop(mr.start())->is_oop(), | |
5321 "Should be an oop"); | |
5322 space->par_oop_iterate(mr, cl); | |
5323 } | |
5324 pst->all_tasks_completed(); | |
5325 } | |
5326 | |
5327 void | |
5328 CMSParRemarkTask::do_dirty_card_rescan_tasks( | |
5329 CompactibleFreeListSpace* sp, int i, | |
5330 Par_MarkRefsIntoAndScanClosure* cl) { | |
5331 // Until all tasks completed: | |
5332 // . claim an unclaimed task | |
5333 // . compute region boundaries corresponding to task claimed | |
5334 // . transfer dirty bits ct->mut for that region | |
5335 // . apply rescanclosure to dirty mut bits for that region | |
5336 | |
5337 ResourceMark rm; | |
5338 HandleMark hm; | |
5339 | |
5340 OopTaskQueue* work_q = work_queue(i); | |
5341 ModUnionClosure modUnionClosure(&(_collector->_modUnionTable)); | |
5342 // CAUTION! CAUTION! CAUTION! CAUTION! CAUTION! CAUTION! CAUTION! | |
5343 // CAUTION: This closure has state that persists across calls to | |
5344 // the work method dirty_range_iterate_clear() in that it has | |
5345 // imbedded in it a (subtype of) UpwardsObjectClosure. The | |
5346 // use of that state in the imbedded UpwardsObjectClosure instance | |
5347 // assumes that the cards are always iterated (even if in parallel | |
5348 // by several threads) in monotonically increasing order per each | |
5349 // thread. This is true of the implementation below which picks | |
5350 // card ranges (chunks) in monotonically increasing order globally | |
5351 // and, a-fortiori, in monotonically increasing order per thread | |
5352 // (the latter order being a subsequence of the former). | |
5353 // If the work code below is ever reorganized into a more chaotic | |
5354 // work-partitioning form than the current "sequential tasks" | |
5355 // paradigm, the use of that persistent state will have to be | |
5356 // revisited and modified appropriately. See also related | |
5357 // bug 4756801 work on which should examine this code to make | |
5358 // sure that the changes there do not run counter to the | |
5359 // assumptions made here and necessary for correctness and | |
5360 // efficiency. Note also that this code might yield inefficient | |
5361 // behaviour in the case of very large objects that span one or | |
5362 // more work chunks. Such objects would potentially be scanned | |
5363 // several times redundantly. Work on 4756801 should try and | |
5364 // address that performance anomaly if at all possible. XXX | |
5365 MemRegion full_span = _collector->_span; | |
5366 CMSBitMap* bm = &(_collector->_markBitMap); // shared | |
5367 MarkFromDirtyCardsClosure | |
5368 greyRescanClosure(_collector, full_span, // entire span of interest | |
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5369 sp, bm, work_q, cl); |
0 | 5370 |
5371 SequentialSubTasksDone* pst = sp->conc_par_seq_tasks(); | |
5372 assert(pst->valid(), "Uninitialized use?"); | |
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5373 uint nth_task = 0; |
0 | 5374 const int alignment = CardTableModRefBS::card_size * BitsPerWord; |
5375 MemRegion span = sp->used_region(); | |
5376 HeapWord* start_addr = span.start(); | |
5377 HeapWord* end_addr = (HeapWord*)round_to((intptr_t)span.end(), | |
5378 alignment); | |
5379 const size_t chunk_size = sp->rescan_task_size(); // in HeapWord units | |
5380 assert((HeapWord*)round_to((intptr_t)start_addr, alignment) == | |
5381 start_addr, "Check alignment"); | |
5382 assert((size_t)round_to((intptr_t)chunk_size, alignment) == | |
5383 chunk_size, "Check alignment"); | |
5384 | |
5385 while (!pst->is_task_claimed(/* reference */ nth_task)) { | |
5386 // Having claimed the nth_task, compute corresponding mem-region, | |
5387 // which is a-fortiori aligned correctly (i.e. at a MUT bopundary). | |
5388 // The alignment restriction ensures that we do not need any | |
5389 // synchronization with other gang-workers while setting or | |
5390 // clearing bits in thus chunk of the MUT. | |
5391 MemRegion this_span = MemRegion(start_addr + nth_task*chunk_size, | |
5392 start_addr + (nth_task+1)*chunk_size); | |
5393 // The last chunk's end might be way beyond end of the | |
5394 // used region. In that case pull back appropriately. | |
5395 if (this_span.end() > end_addr) { | |
5396 this_span.set_end(end_addr); | |
5397 assert(!this_span.is_empty(), "Program logic (calculation of n_tasks)"); | |
5398 } | |
5399 // Iterate over the dirty cards covering this chunk, marking them | |
5400 // precleaned, and setting the corresponding bits in the mod union | |
5401 // table. Since we have been careful to partition at Card and MUT-word | |
5402 // boundaries no synchronization is needed between parallel threads. | |
5403 _collector->_ct->ct_bs()->dirty_card_iterate(this_span, | |
5404 &modUnionClosure); | |
5405 | |
5406 // Having transferred these marks into the modUnionTable, | |
5407 // rescan the marked objects on the dirty cards in the modUnionTable. | |
5408 // Even if this is at a synchronous collection, the initial marking | |
5409 // may have been done during an asynchronous collection so there | |
5410 // may be dirty bits in the mod-union table. | |
5411 _collector->_modUnionTable.dirty_range_iterate_clear( | |
5412 this_span, &greyRescanClosure); | |
5413 _collector->_modUnionTable.verifyNoOneBitsInRange( | |
5414 this_span.start(), | |
5415 this_span.end()); | |
5416 } | |
5417 pst->all_tasks_completed(); // declare that i am done | |
5418 } | |
5419 | |
5420 // . see if we can share work_queues with ParNew? XXX | |
5421 void | |
5422 CMSParRemarkTask::do_work_steal(int i, Par_MarkRefsIntoAndScanClosure* cl, | |
5423 int* seed) { | |
5424 OopTaskQueue* work_q = work_queue(i); | |
5425 NOT_PRODUCT(int num_steals = 0;) | |
5426 oop obj_to_scan; | |
5427 CMSBitMap* bm = &(_collector->_markBitMap); | |
5428 | |
5429 while (true) { | |
5430 // Completely finish any left over work from (an) earlier round(s) | |
5431 cl->trim_queue(0); | |
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5432 size_t num_from_overflow_list = MIN2((size_t)(work_q->max_elems() - work_q->size())/4, |
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5433 (size_t)ParGCDesiredObjsFromOverflowList); |
0 | 5434 // Now check if there's any work in the overflow list |
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5435 // Passing ParallelGCThreads as the third parameter, no_of_gc_threads, |
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5436 // only affects the number of attempts made to get work from the |
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5437 // overflow list and does not affect the number of workers. Just |
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5438 // pass ParallelGCThreads so this behavior is unchanged. |
0 | 5439 if (_collector->par_take_from_overflow_list(num_from_overflow_list, |
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5440 work_q, |
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5441 ParallelGCThreads)) { |
0 | 5442 // found something in global overflow list; |
5443 // not yet ready to go stealing work from others. | |
5444 // We'd like to assert(work_q->size() != 0, ...) | |
5445 // because we just took work from the overflow list, | |
5446 // but of course we can't since all of that could have | |
5447 // been already stolen from us. | |
5448 // "He giveth and He taketh away." | |
5449 continue; | |
5450 } | |
5451 // Verify that we have no work before we resort to stealing | |
5452 assert(work_q->size() == 0, "Have work, shouldn't steal"); | |
5453 // Try to steal from other queues that have work | |
5454 if (task_queues()->steal(i, seed, /* reference */ obj_to_scan)) { | |
5455 NOT_PRODUCT(num_steals++;) | |
5456 assert(obj_to_scan->is_oop(), "Oops, not an oop!"); | |
5457 assert(bm->isMarked((HeapWord*)obj_to_scan), "Stole an unmarked oop?"); | |
5458 // Do scanning work | |
5459 obj_to_scan->oop_iterate(cl); | |
5460 // Loop around, finish this work, and try to steal some more | |
5461 } else if (terminator()->offer_termination()) { | |
5462 break; // nirvana from the infinite cycle | |
5463 } | |
5464 } | |
5465 NOT_PRODUCT( | |
5466 if (PrintCMSStatistics != 0) { | |
5467 gclog_or_tty->print("\n\t(%d: stole %d oops)", i, num_steals); | |
5468 } | |
5469 ) | |
5470 assert(work_q->size() == 0 && _collector->overflow_list_is_empty(), | |
5471 "Else our work is not yet done"); | |
5472 } | |
5473 | |
5474 // Return a thread-local PLAB recording array, as appropriate. | |
5475 void* CMSCollector::get_data_recorder(int thr_num) { | |
5476 if (_survivor_plab_array != NULL && | |
5477 (CMSPLABRecordAlways || | |
5478 (_collectorState > Marking && _collectorState < FinalMarking))) { | |
5479 assert(thr_num < (int)ParallelGCThreads, "thr_num is out of bounds"); | |
5480 ChunkArray* ca = &_survivor_plab_array[thr_num]; | |
5481 ca->reset(); // clear it so that fresh data is recorded | |
5482 return (void*) ca; | |
5483 } else { | |
5484 return NULL; | |
5485 } | |
5486 } | |
5487 | |
5488 // Reset all the thread-local PLAB recording arrays | |
5489 void CMSCollector::reset_survivor_plab_arrays() { | |
5490 for (uint i = 0; i < ParallelGCThreads; i++) { | |
5491 _survivor_plab_array[i].reset(); | |
5492 } | |
5493 } | |
5494 | |
5495 // Merge the per-thread plab arrays into the global survivor chunk | |
5496 // array which will provide the partitioning of the survivor space | |
5497 // for CMS rescan. | |
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5498 void CMSCollector::merge_survivor_plab_arrays(ContiguousSpace* surv, |
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5499 int no_of_gc_threads) { |
0 | 5500 assert(_survivor_plab_array != NULL, "Error"); |
5501 assert(_survivor_chunk_array != NULL, "Error"); | |
5502 assert(_collectorState == FinalMarking, "Error"); | |
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5503 for (int j = 0; j < no_of_gc_threads; j++) { |
0 | 5504 _cursor[j] = 0; |
5505 } | |
5506 HeapWord* top = surv->top(); | |
5507 size_t i; | |
5508 for (i = 0; i < _survivor_chunk_capacity; i++) { // all sca entries | |
5509 HeapWord* min_val = top; // Higher than any PLAB address | |
5510 uint min_tid = 0; // position of min_val this round | |
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5511 for (int j = 0; j < no_of_gc_threads; j++) { |
0 | 5512 ChunkArray* cur_sca = &_survivor_plab_array[j]; |
5513 if (_cursor[j] == cur_sca->end()) { | |
5514 continue; | |
5515 } | |
5516 assert(_cursor[j] < cur_sca->end(), "ctl pt invariant"); | |
5517 HeapWord* cur_val = cur_sca->nth(_cursor[j]); | |
5518 assert(surv->used_region().contains(cur_val), "Out of bounds value"); | |
5519 if (cur_val < min_val) { | |
5520 min_tid = j; | |
5521 min_val = cur_val; | |
5522 } else { | |
5523 assert(cur_val < top, "All recorded addresses should be less"); | |
5524 } | |
5525 } | |
5526 // At this point min_val and min_tid are respectively | |
5527 // the least address in _survivor_plab_array[j]->nth(_cursor[j]) | |
5528 // and the thread (j) that witnesses that address. | |
5529 // We record this address in the _survivor_chunk_array[i] | |
5530 // and increment _cursor[min_tid] prior to the next round i. | |
5531 if (min_val == top) { | |
5532 break; | |
5533 } | |
5534 _survivor_chunk_array[i] = min_val; | |
5535 _cursor[min_tid]++; | |
5536 } | |
5537 // We are all done; record the size of the _survivor_chunk_array | |
5538 _survivor_chunk_index = i; // exclusive: [0, i) | |
5539 if (PrintCMSStatistics > 0) { | |
5540 gclog_or_tty->print(" (Survivor:" SIZE_FORMAT "chunks) ", i); | |
5541 } | |
5542 // Verify that we used up all the recorded entries | |
5543 #ifdef ASSERT | |
5544 size_t total = 0; | |
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5545 for (int j = 0; j < no_of_gc_threads; j++) { |
0 | 5546 assert(_cursor[j] == _survivor_plab_array[j].end(), "Ctl pt invariant"); |
5547 total += _cursor[j]; | |
5548 } | |
5549 assert(total == _survivor_chunk_index, "Ctl Pt Invariant"); | |
5550 // Check that the merged array is in sorted order | |
5551 if (total > 0) { | |
5552 for (size_t i = 0; i < total - 1; i++) { | |
5553 if (PrintCMSStatistics > 0) { | |
5554 gclog_or_tty->print(" (chunk" SIZE_FORMAT ":" INTPTR_FORMAT ") ", | |
5555 i, _survivor_chunk_array[i]); | |
5556 } | |
5557 assert(_survivor_chunk_array[i] < _survivor_chunk_array[i+1], | |
5558 "Not sorted"); | |
5559 } | |
5560 } | |
5561 #endif // ASSERT | |
5562 } | |
5563 | |
5564 // Set up the space's par_seq_tasks structure for work claiming | |
5565 // for parallel rescan of young gen. | |
5566 // See ParRescanTask where this is currently used. | |
5567 void | |
5568 CMSCollector:: | |
5569 initialize_sequential_subtasks_for_young_gen_rescan(int n_threads) { | |
5570 assert(n_threads > 0, "Unexpected n_threads argument"); | |
5571 DefNewGeneration* dng = (DefNewGeneration*)_young_gen; | |
5572 | |
5573 // Eden space | |
5574 { | |
5575 SequentialSubTasksDone* pst = dng->eden()->par_seq_tasks(); | |
5576 assert(!pst->valid(), "Clobbering existing data?"); | |
5577 // Each valid entry in [0, _eden_chunk_index) represents a task. | |
5578 size_t n_tasks = _eden_chunk_index + 1; | |
5579 assert(n_tasks == 1 || _eden_chunk_array != NULL, "Error"); | |
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5580 // Sets the condition for completion of the subtask (how many threads |
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5581 // need to finish in order to be done). |
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5582 pst->set_n_threads(n_threads); |
0 | 5583 pst->set_n_tasks((int)n_tasks); |
5584 } | |
5585 | |
5586 // Merge the survivor plab arrays into _survivor_chunk_array | |
5587 if (_survivor_plab_array != NULL) { | |
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5588 merge_survivor_plab_arrays(dng->from(), n_threads); |
0 | 5589 } else { |
5590 assert(_survivor_chunk_index == 0, "Error"); | |
5591 } | |
5592 | |
5593 // To space | |
5594 { | |
5595 SequentialSubTasksDone* pst = dng->to()->par_seq_tasks(); | |
5596 assert(!pst->valid(), "Clobbering existing data?"); | |
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5597 // Sets the condition for completion of the subtask (how many threads |
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5598 // need to finish in order to be done). |
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5599 pst->set_n_threads(n_threads); |
0 | 5600 pst->set_n_tasks(1); |
5601 assert(pst->valid(), "Error"); | |
5602 } | |
5603 | |
5604 // From space | |
5605 { | |
5606 SequentialSubTasksDone* pst = dng->from()->par_seq_tasks(); | |
5607 assert(!pst->valid(), "Clobbering existing data?"); | |
5608 size_t n_tasks = _survivor_chunk_index + 1; | |
5609 assert(n_tasks == 1 || _survivor_chunk_array != NULL, "Error"); | |
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5610 // Sets the condition for completion of the subtask (how many threads |
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5611 // need to finish in order to be done). |
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5612 pst->set_n_threads(n_threads); |
0 | 5613 pst->set_n_tasks((int)n_tasks); |
5614 assert(pst->valid(), "Error"); | |
5615 } | |
5616 } | |
5617 | |
5618 // Parallel version of remark | |
5619 void CMSCollector::do_remark_parallel() { | |
5620 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
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5621 FlexibleWorkGang* workers = gch->workers(); |
0 | 5622 assert(workers != NULL, "Need parallel worker threads."); |
4095
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5623 // Choose to use the number of GC workers most recently set |
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5624 // into "active_workers". If active_workers is not set, set it |
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|
5625 // to ParallelGCThreads. |
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5626 int n_workers = workers->active_workers(); |
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5627 if (n_workers == 0) { |
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|
5628 assert(n_workers > 0, "Should have been set during scavenge"); |
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5629 n_workers = ParallelGCThreads; |
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5630 workers->set_active_workers(n_workers); |
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5631 } |
0 | 5632 CompactibleFreeListSpace* cms_space = _cmsGen->cmsSpace(); |
5633 | |
5634 CMSParRemarkTask tsk(this, | |
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5635 cms_space, |
0 | 5636 n_workers, workers, task_queues()); |
5637 | |
5638 // Set up for parallel process_strong_roots work. | |
5639 gch->set_par_threads(n_workers); | |
5640 // We won't be iterating over the cards in the card table updating | |
5641 // the younger_gen cards, so we shouldn't call the following else | |
5642 // the verification code as well as subsequent younger_refs_iterate | |
5643 // code would get confused. XXX | |
5644 // gch->rem_set()->prepare_for_younger_refs_iterate(true); // parallel | |
5645 | |
5646 // The young gen rescan work will not be done as part of | |
5647 // process_strong_roots (which currently doesn't knw how to | |
5648 // parallelize such a scan), but rather will be broken up into | |
5649 // a set of parallel tasks (via the sampling that the [abortable] | |
5650 // preclean phase did of EdenSpace, plus the [two] tasks of | |
5651 // scanning the [two] survivor spaces. Further fine-grain | |
5652 // parallelization of the scanning of the survivor spaces | |
5653 // themselves, and of precleaning of the younger gen itself | |
5654 // is deferred to the future. | |
5655 initialize_sequential_subtasks_for_young_gen_rescan(n_workers); | |
5656 | |
5657 // The dirty card rescan work is broken up into a "sequence" | |
5658 // of parallel tasks (per constituent space) that are dynamically | |
5659 // claimed by the parallel threads. | |
5660 cms_space->initialize_sequential_subtasks_for_rescan(n_workers); | |
5661 | |
5662 // It turns out that even when we're using 1 thread, doing the work in a | |
5663 // separate thread causes wide variance in run times. We can't help this | |
5664 // in the multi-threaded case, but we special-case n=1 here to get | |
5665 // repeatable measurements of the 1-thread overhead of the parallel code. | |
5666 if (n_workers > 1) { | |
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5667 // Make refs discovery MT-safe, if it isn't already: it may not |
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5668 // necessarily be so, since it's possible that we are doing |
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5669 // ST marking. |
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5670 ReferenceProcessorMTDiscoveryMutator mt(ref_processor(), true); |
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5671 GenCollectedHeap::StrongRootsScope srs(gch); |
0 | 5672 workers->run_task(&tsk); |
5673 } else { | |
4876
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5674 ReferenceProcessorMTDiscoveryMutator mt(ref_processor(), false); |
989
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5675 GenCollectedHeap::StrongRootsScope srs(gch); |
0 | 5676 tsk.work(0); |
5677 } | |
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5678 |
0 | 5679 gch->set_par_threads(0); // 0 ==> non-parallel. |
5680 // restore, single-threaded for now, any preserved marks | |
5681 // as a result of work_q overflow | |
5682 restore_preserved_marks_if_any(); | |
5683 } | |
5684 | |
5685 // Non-parallel version of remark | |
5686 void CMSCollector::do_remark_non_parallel() { | |
5687 ResourceMark rm; | |
5688 HandleMark hm; | |
5689 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
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5690 ReferenceProcessorMTDiscoveryMutator mt(ref_processor(), false); |
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5691 |
0 | 5692 MarkRefsIntoAndScanClosure |
6725
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5693 mrias_cl(_span, ref_processor(), &_markBitMap, NULL /* not precleaning */, |
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5694 &_markStack, this, |
0 | 5695 false /* should_yield */, false /* not precleaning */); |
5696 MarkFromDirtyCardsClosure | |
5697 markFromDirtyCardsClosure(this, _span, | |
5698 NULL, // space is set further below | |
6725
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5699 &_markBitMap, &_markStack, &mrias_cl); |
0 | 5700 { |
5701 TraceTime t("grey object rescan", PrintGCDetails, false, gclog_or_tty); | |
342
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5702 // Iterate over the dirty cards, setting the corresponding bits in the |
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|
5703 // mod union table. |
0 | 5704 { |
5705 ModUnionClosure modUnionClosure(&_modUnionTable); | |
5706 _ct->ct_bs()->dirty_card_iterate( | |
5707 _cmsGen->used_region(), | |
5708 &modUnionClosure); | |
5709 } | |
5710 // Having transferred these marks into the modUnionTable, we just need | |
5711 // to rescan the marked objects on the dirty cards in the modUnionTable. | |
5712 // The initial marking may have been done during an asynchronous | |
5713 // collection so there may be dirty bits in the mod-union table. | |
5714 const int alignment = | |
5715 CardTableModRefBS::card_size * BitsPerWord; | |
5716 { | |
5717 // ... First handle dirty cards in CMS gen | |
5718 markFromDirtyCardsClosure.set_space(_cmsGen->cmsSpace()); | |
5719 MemRegion ur = _cmsGen->used_region(); | |
5720 HeapWord* lb = ur.start(); | |
5721 HeapWord* ub = (HeapWord*)round_to((intptr_t)ur.end(), alignment); | |
5722 MemRegion cms_span(lb, ub); | |
5723 _modUnionTable.dirty_range_iterate_clear(cms_span, | |
5724 &markFromDirtyCardsClosure); | |
5725 verify_work_stacks_empty(); | |
5726 if (PrintCMSStatistics != 0) { | |
5727 gclog_or_tty->print(" (re-scanned "SIZE_FORMAT" dirty cards in cms gen) ", | |
5728 markFromDirtyCardsClosure.num_dirty_cards()); | |
5729 } | |
5730 } | |
5731 } | |
5732 if (VerifyDuringGC && | |
5733 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
5734 HandleMark hm; // Discard invalid handles created during verification | |
6865
4202510ee0fe
8000831: Heap verification output incorrect/incomplete
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6787
diff
changeset
|
5735 Universe::verify(); |
0 | 5736 } |
5737 { | |
5738 TraceTime t("root rescan", PrintGCDetails, false, gclog_or_tty); | |
5739 | |
5740 verify_work_stacks_empty(); | |
5741 | |
5742 gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel. | |
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|
5743 GenCollectedHeap::StrongRootsScope srs(gch); |
0 | 5744 gch->gen_process_strong_roots(_cmsGen->level(), |
5745 true, // younger gens as roots | |
989
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|
5746 false, // use the local StrongRootsScope |
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5747 false, // not scavenging |
0 | 5748 SharedHeap::ScanningOption(roots_scanning_options()), |
989
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|
5749 &mrias_cl, |
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|
5750 true, // walk code active on stacks |
6725
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|
5751 NULL, |
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|
5752 NULL); // The dirty klasses will be handled below |
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|
5753 |
989
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changeset
|
5754 assert(should_unload_classes() |
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|
5755 || (roots_scanning_options() & SharedHeap::SO_CodeCache), |
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|
5756 "if we didn't scan the code cache, we have to be ready to drop nmethods with expired weak oops"); |
0 | 5757 } |
6725
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|
5758 |
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|
5759 { |
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|
5760 TraceTime t("visit unhandled CLDs", PrintGCDetails, false, gclog_or_tty); |
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|
5761 |
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|
5762 verify_work_stacks_empty(); |
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|
5763 |
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|
5764 // Scan all class loader data objects that might have been introduced |
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changeset
|
5765 // during concurrent marking. |
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|
5766 ResourceMark rm; |
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|
5767 GrowableArray<ClassLoaderData*>* array = ClassLoaderDataGraph::new_clds(); |
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|
5768 for (int i = 0; i < array->length(); i++) { |
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|
5769 mrias_cl.do_class_loader_data(array->at(i)); |
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|
5770 } |
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|
5771 |
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|
5772 // We don't need to keep track of new CLDs anymore. |
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|
5773 ClassLoaderDataGraph::remember_new_clds(false); |
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|
5774 |
da91efe96a93
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changeset
|
5775 verify_work_stacks_empty(); |
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|
5776 } |
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|
5777 |
da91efe96a93
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|
5778 { |
da91efe96a93
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diff
changeset
|
5779 TraceTime t("dirty klass scan", PrintGCDetails, false, gclog_or_tty); |
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|
5780 |
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|
5781 verify_work_stacks_empty(); |
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|
5782 |
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|
5783 RemarkKlassClosure remark_klass_closure(&mrias_cl); |
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|
5784 ClassLoaderDataGraph::classes_do(&remark_klass_closure); |
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|
5785 |
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|
5786 verify_work_stacks_empty(); |
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|
5787 } |
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|
5788 |
da91efe96a93
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|
5789 // We might have added oops to ClassLoaderData::_handles during the |
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|
5790 // concurrent marking phase. These oops point to newly allocated objects |
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|
5791 // that are guaranteed to be kept alive. Either by the direct allocation |
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|
5792 // code, or when the young collector processes the strong roots. Hence, |
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|
5793 // we don't have to revisit the _handles block during the remark phase. |
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|
5794 |
0 | 5795 verify_work_stacks_empty(); |
5796 // Restore evacuated mark words, if any, used for overflow list links | |
5797 if (!CMSOverflowEarlyRestoration) { | |
5798 restore_preserved_marks_if_any(); | |
5799 } | |
5800 verify_overflow_empty(); | |
5801 } | |
5802 | |
5803 //////////////////////////////////////////////////////// | |
5804 // Parallel Reference Processing Task Proxy Class | |
5805 //////////////////////////////////////////////////////// | |
1833
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|
5806 class CMSRefProcTaskProxy: public AbstractGangTaskWOopQueues { |
0 | 5807 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; |
5808 CMSCollector* _collector; | |
5809 CMSBitMap* _mark_bit_map; | |
143
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6662086: 6u4+, 7b11+: CMS never clears referents when -XX:+ParallelRefProcEnabled
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113
diff
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|
5810 const MemRegion _span; |
0 | 5811 ProcessTask& _task; |
5812 | |
5813 public: | |
5814 CMSRefProcTaskProxy(ProcessTask& task, | |
5815 CMSCollector* collector, | |
5816 const MemRegion& span, | |
5817 CMSBitMap* mark_bit_map, | |
1833
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jmasa
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diff
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|
5818 AbstractWorkGang* workers, |
0 | 5819 OopTaskQueueSet* task_queues): |
2369
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|
5820 // XXX Should superclass AGTWOQ also know about AWG since it knows |
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|
5821 // about the task_queues used by the AWG? Then it could initialize |
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|
5822 // the terminator() object. See 6984287. The set_for_termination() |
92da084fefc9
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|
5823 // below is a temporary band-aid for the regression in 6984287. |
1833
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|
5824 AbstractGangTaskWOopQueues("Process referents by policy in parallel", |
8b10f48633dc
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|
5825 task_queues), |
0 | 5826 _task(task), |
1833
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|
5827 _collector(collector), _span(span), _mark_bit_map(mark_bit_map) |
2369
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|
5828 { |
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diff
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|
5829 assert(_collector->_span.equals(_span) && !_span.is_empty(), |
92da084fefc9
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|
5830 "Inconsistency in _span"); |
92da084fefc9
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|
5831 set_for_termination(workers->active_workers()); |
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|
5832 } |
0 | 5833 |
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|
5834 OopTaskQueueSet* task_queues() { return queues(); } |
0 | 5835 |
5836 OopTaskQueue* work_queue(int i) { return task_queues()->queue(i); } | |
5837 | |
5838 void do_work_steal(int i, | |
5839 CMSParDrainMarkingStackClosure* drain, | |
5840 CMSParKeepAliveClosure* keep_alive, | |
5841 int* seed); | |
5842 | |
4728
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|
5843 virtual void work(uint worker_id); |
0 | 5844 }; |
5845 | |
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|
5846 void CMSRefProcTaskProxy::work(uint worker_id) { |
143
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|
5847 assert(_collector->_span.equals(_span), "Inconsistency in _span"); |
0 | 5848 CMSParKeepAliveClosure par_keep_alive(_collector, _span, |
935 | 5849 _mark_bit_map, |
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|
5850 work_queue(worker_id)); |
0 | 5851 CMSParDrainMarkingStackClosure par_drain_stack(_collector, _span, |
935 | 5852 _mark_bit_map, |
4728
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|
5853 work_queue(worker_id)); |
143
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5854 CMSIsAliveClosure is_alive_closure(_span, _mark_bit_map); |
4728
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jmasa
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diff
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|
5855 _task.work(worker_id, is_alive_closure, par_keep_alive, par_drain_stack); |
0 | 5856 if (_task.marks_oops_alive()) { |
4728
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changeset
|
5857 do_work_steal(worker_id, &par_drain_stack, &par_keep_alive, |
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jmasa
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|
5858 _collector->hash_seed(worker_id)); |
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|
5859 } |
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|
5860 assert(work_queue(worker_id)->size() == 0, "work_queue should be empty"); |
0 | 5861 assert(_collector->_overflow_list == NULL, "non-empty _overflow_list"); |
5862 } | |
5863 | |
5864 class CMSRefEnqueueTaskProxy: public AbstractGangTask { | |
5865 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; | |
5866 EnqueueTask& _task; | |
5867 | |
5868 public: | |
5869 CMSRefEnqueueTaskProxy(EnqueueTask& task) | |
5870 : AbstractGangTask("Enqueue reference objects in parallel"), | |
5871 _task(task) | |
5872 { } | |
5873 | |
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|
5874 virtual void work(uint worker_id) |
0 | 5875 { |
4728
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changeset
|
5876 _task.work(worker_id); |
0 | 5877 } |
5878 }; | |
5879 | |
5880 CMSParKeepAliveClosure::CMSParKeepAliveClosure(CMSCollector* collector, | |
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changeset
|
5881 MemRegion span, CMSBitMap* bit_map, OopTaskQueue* work_queue): |
0 | 5882 _span(span), |
5883 _bit_map(bit_map), | |
5884 _work_queue(work_queue), | |
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5885 _mark_and_push(collector, span, bit_map, work_queue), |
0 | 5886 _low_water_mark(MIN2((uint)(work_queue->max_elems()/4), |
5887 (uint)(CMSWorkQueueDrainThreshold * ParallelGCThreads))) | |
5888 { } | |
5889 | |
5890 // . see if we can share work_queues with ParNew? XXX | |
5891 void CMSRefProcTaskProxy::do_work_steal(int i, | |
5892 CMSParDrainMarkingStackClosure* drain, | |
5893 CMSParKeepAliveClosure* keep_alive, | |
5894 int* seed) { | |
5895 OopTaskQueue* work_q = work_queue(i); | |
5896 NOT_PRODUCT(int num_steals = 0;) | |
5897 oop obj_to_scan; | |
5898 | |
5899 while (true) { | |
5900 // Completely finish any left over work from (an) earlier round(s) | |
5901 drain->trim_queue(0); | |
679
cea947c8a988
6819891: ParNew: Fix work queue overflow code to deal correctly with +UseCompressedOops
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628
diff
changeset
|
5902 size_t num_from_overflow_list = MIN2((size_t)(work_q->max_elems() - work_q->size())/4, |
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6819891: ParNew: Fix work queue overflow code to deal correctly with +UseCompressedOops
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628
diff
changeset
|
5903 (size_t)ParGCDesiredObjsFromOverflowList); |
0 | 5904 // Now check if there's any work in the overflow list |
1833
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|
5905 // Passing ParallelGCThreads as the third parameter, no_of_gc_threads, |
8b10f48633dc
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|
5906 // only affects the number of attempts made to get work from the |
8b10f48633dc
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changeset
|
5907 // overflow list and does not affect the number of workers. Just |
8b10f48633dc
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jmasa
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changeset
|
5908 // pass ParallelGCThreads so this behavior is unchanged. |
0 | 5909 if (_collector->par_take_from_overflow_list(num_from_overflow_list, |
1833
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|
5910 work_q, |
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diff
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|
5911 ParallelGCThreads)) { |
0 | 5912 // Found something in global overflow list; |
5913 // not yet ready to go stealing work from others. | |
5914 // We'd like to assert(work_q->size() != 0, ...) | |
5915 // because we just took work from the overflow list, | |
5916 // but of course we can't, since all of that might have | |
5917 // been already stolen from us. | |
5918 continue; | |
5919 } | |
5920 // Verify that we have no work before we resort to stealing | |
5921 assert(work_q->size() == 0, "Have work, shouldn't steal"); | |
5922 // Try to steal from other queues that have work | |
5923 if (task_queues()->steal(i, seed, /* reference */ obj_to_scan)) { | |
5924 NOT_PRODUCT(num_steals++;) | |
5925 assert(obj_to_scan->is_oop(), "Oops, not an oop!"); | |
5926 assert(_mark_bit_map->isMarked((HeapWord*)obj_to_scan), "Stole an unmarked oop?"); | |
5927 // Do scanning work | |
5928 obj_to_scan->oop_iterate(keep_alive); | |
5929 // Loop around, finish this work, and try to steal some more | |
5930 } else if (terminator()->offer_termination()) { | |
5931 break; // nirvana from the infinite cycle | |
5932 } | |
5933 } | |
5934 NOT_PRODUCT( | |
5935 if (PrintCMSStatistics != 0) { | |
5936 gclog_or_tty->print("\n\t(%d: stole %d oops)", i, num_steals); | |
5937 } | |
5938 ) | |
5939 } | |
5940 | |
5941 void CMSRefProcTaskExecutor::execute(ProcessTask& task) | |
5942 { | |
5943 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
1833
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|
5944 FlexibleWorkGang* workers = gch->workers(); |
0 | 5945 assert(workers != NULL, "Need parallel worker threads."); |
5946 CMSRefProcTaskProxy rp_task(task, &_collector, | |
5947 _collector.ref_processor()->span(), | |
5948 _collector.markBitMap(), | |
1833
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jmasa
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diff
changeset
|
5949 workers, _collector.task_queues()); |
0 | 5950 workers->run_task(&rp_task); |
5951 } | |
5952 | |
5953 void CMSRefProcTaskExecutor::execute(EnqueueTask& task) | |
5954 { | |
5955 | |
5956 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
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|
5957 FlexibleWorkGang* workers = gch->workers(); |
0 | 5958 assert(workers != NULL, "Need parallel worker threads."); |
5959 CMSRefEnqueueTaskProxy enq_task(task); | |
5960 workers->run_task(&enq_task); | |
5961 } | |
5962 | |
5963 void CMSCollector::refProcessingWork(bool asynch, bool clear_all_soft_refs) { | |
5964 | |
5965 ResourceMark rm; | |
5966 HandleMark hm; | |
5967 | |
5968 ReferenceProcessor* rp = ref_processor(); | |
5969 assert(rp->span().equals(_span), "Spans should be equal"); | |
453
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diff
changeset
|
5970 assert(!rp->enqueuing_is_done(), "Enqueuing should not be complete"); |
c96030fff130
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diff
changeset
|
5971 // Process weak references. |
457
27a80744a83b
6778647: snap(), snap_policy() should be renamed setup(), setup_policy()
ysr
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453
diff
changeset
|
5972 rp->setup_policy(clear_all_soft_refs); |
453
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diff
changeset
|
5973 verify_work_stacks_empty(); |
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changeset
|
5974 |
0 | 5975 CMSKeepAliveClosure cmsKeepAliveClosure(this, _span, &_markBitMap, |
6725
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6964458: Reimplement class meta-data storage to use native memory
coleenp
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changeset
|
5976 &_markStack, false /* !preclean */); |
0 | 5977 CMSDrainMarkingStackClosure cmsDrainMarkingStackClosure(this, |
5978 _span, &_markBitMap, &_markStack, | |
452
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
5979 &cmsKeepAliveClosure, false /* !preclean */); |
0 | 5980 { |
5981 TraceTime t("weak refs processing", PrintGCDetails, false, gclog_or_tty); | |
5982 if (rp->processing_is_mt()) { | |
1833
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diff
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|
5983 // Set the degree of MT here. If the discovery is done MT, there |
8b10f48633dc
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jmasa
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diff
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|
5984 // may have been a different number of threads doing the discovery |
8b10f48633dc
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changeset
|
5985 // and a different number of discovered lists may have Ref objects. |
8b10f48633dc
6984287: Regularize how GC parallel workers are specified.
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diff
changeset
|
5986 // That is OK as long as the Reference lists are balanced (see |
8b10f48633dc
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jmasa
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diff
changeset
|
5987 // balance_all_queues() and balance_queues()). |
4095
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
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diff
changeset
|
5988 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
bca17e38de00
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diff
changeset
|
5989 int active_workers = ParallelGCThreads; |
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
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3979
diff
changeset
|
5990 FlexibleWorkGang* workers = gch->workers(); |
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
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diff
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|
5991 if (workers != NULL) { |
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
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diff
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|
5992 active_workers = workers->active_workers(); |
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diff
changeset
|
5993 // The expectation is that active_workers will have already |
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
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|
5994 // been set to a reasonable value. If it has not been set, |
bca17e38de00
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3979
diff
changeset
|
5995 // investigate. |
bca17e38de00
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3979
diff
changeset
|
5996 assert(active_workers > 0, "Should have been set during scavenge"); |
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
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3979
diff
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|
5997 } |
bca17e38de00
6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads
jmasa
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diff
changeset
|
5998 rp->set_active_mt_degree(active_workers); |
0 | 5999 CMSRefProcTaskExecutor task_executor(*this); |
453
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6684579: SoftReference processing can be made more efficient
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diff
changeset
|
6000 rp->process_discovered_references(&_is_alive_closure, |
0 | 6001 &cmsKeepAliveClosure, |
6002 &cmsDrainMarkingStackClosure, | |
6003 &task_executor); | |
6004 } else { | |
453
c96030fff130
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ysr
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diff
changeset
|
6005 rp->process_discovered_references(&_is_alive_closure, |
0 | 6006 &cmsKeepAliveClosure, |
6007 &cmsDrainMarkingStackClosure, | |
6008 NULL); | |
6009 } | |
10188
2f50bc369470
8013160: NPG: Remove unnecessary mark stack draining after CodeCache::do_unloading
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parents:
10186
diff
changeset
|
6010 } |
2f50bc369470
8013160: NPG: Remove unnecessary mark stack draining after CodeCache::do_unloading
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diff
changeset
|
6011 |
2f50bc369470
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10186
diff
changeset
|
6012 // This is the point where the entire marking should have completed. |
2f50bc369470
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stefank
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10186
diff
changeset
|
6013 verify_work_stacks_empty(); |
0 | 6014 |
94
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
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parents:
9
diff
changeset
|
6015 if (should_unload_classes()) { |
0 | 6016 { |
6017 TraceTime t("class unloading", PrintGCDetails, false, gclog_or_tty); | |
6018 | |
10188
2f50bc369470
8013160: NPG: Remove unnecessary mark stack draining after CodeCache::do_unloading
stefank
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10186
diff
changeset
|
6019 // Unload classes and purge the SystemDictionary. |
0 | 6020 bool purged_class = SystemDictionary::do_unloading(&_is_alive_closure); |
6021 | |
10188
2f50bc369470
8013160: NPG: Remove unnecessary mark stack draining after CodeCache::do_unloading
stefank
parents:
10186
diff
changeset
|
6022 // Unload nmethods. |
6787
8966c2d65d96
7200470: KeepAliveClosure not needed in CodeCache::do_unloading
brutisso
parents:
6755
diff
changeset
|
6023 CodeCache::do_unloading(&_is_alive_closure, purged_class); |
0 | 6024 |
10188
2f50bc369470
8013160: NPG: Remove unnecessary mark stack draining after CodeCache::do_unloading
stefank
parents:
10186
diff
changeset
|
6025 // Prune dead klasses from subklass/sibling/implementor lists. |
6725
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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6197
diff
changeset
|
6026 Klass::clean_weak_klass_links(&_is_alive_closure); |
0 | 6027 } |
6028 | |
6029 { | |
2379
b099aaf51bf8
6962931: move interned strings out of the perm gen
jcoomes
parents:
2369
diff
changeset
|
6030 TraceTime t("scrub symbol table", PrintGCDetails, false, gclog_or_tty); |
2177
3582bf76420e
6990754: Use native memory and reference counting to implement SymbolTable
coleenp
parents:
2147
diff
changeset
|
6031 // Clean up unreferenced symbols in symbol table. |
3582bf76420e
6990754: Use native memory and reference counting to implement SymbolTable
coleenp
parents:
2147
diff
changeset
|
6032 SymbolTable::unlink(); |
0 | 6033 } |
6034 } | |
6035 | |
6725
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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diff
changeset
|
6036 // CMS doesn't use the StringTable as hard roots when class unloading is turned off. |
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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diff
changeset
|
6037 // Need to check if we really scanned the StringTable. |
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
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diff
changeset
|
6038 if ((roots_scanning_options() & SharedHeap::SO_Strings) == 0) { |
2379
b099aaf51bf8
6962931: move interned strings out of the perm gen
jcoomes
parents:
2369
diff
changeset
|
6039 TraceTime t("scrub string table", PrintGCDetails, false, gclog_or_tty); |
10188
2f50bc369470
8013160: NPG: Remove unnecessary mark stack draining after CodeCache::do_unloading
stefank
parents:
10186
diff
changeset
|
6040 // Delete entries for dead interned strings. |
2379
b099aaf51bf8
6962931: move interned strings out of the perm gen
jcoomes
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2369
diff
changeset
|
6041 StringTable::unlink(&_is_alive_closure); |
b099aaf51bf8
6962931: move interned strings out of the perm gen
jcoomes
parents:
2369
diff
changeset
|
6042 } |
b099aaf51bf8
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diff
changeset
|
6043 |
0 | 6044 // Restore any preserved marks as a result of mark stack or |
6045 // work queue overflow | |
6046 restore_preserved_marks_if_any(); // done single-threaded for now | |
6047 | |
6048 rp->set_enqueuing_is_done(true); | |
6049 if (rp->processing_is_mt()) { | |
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diff
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|
6050 rp->balance_all_queues(); |
0 | 6051 CMSRefProcTaskExecutor task_executor(*this); |
6052 rp->enqueue_discovered_references(&task_executor); | |
6053 } else { | |
6054 rp->enqueue_discovered_references(NULL); | |
6055 } | |
6056 rp->verify_no_references_recorded(); | |
6057 assert(!rp->discovery_enabled(), "should have been disabled"); | |
6058 } | |
6059 | |
6060 #ifndef PRODUCT | |
6061 void CMSCollector::check_correct_thread_executing() { | |
6062 Thread* t = Thread::current(); | |
6063 // Only the VM thread or the CMS thread should be here. | |
6064 assert(t->is_ConcurrentGC_thread() || t->is_VM_thread(), | |
6065 "Unexpected thread type"); | |
6066 // If this is the vm thread, the foreground process | |
6067 // should not be waiting. Note that _foregroundGCIsActive is | |
6068 // true while the foreground collector is waiting. | |
6069 if (_foregroundGCShouldWait) { | |
6070 // We cannot be the VM thread | |
6071 assert(t->is_ConcurrentGC_thread(), | |
6072 "Should be CMS thread"); | |
6073 } else { | |
6074 // We can be the CMS thread only if we are in a stop-world | |
6075 // phase of CMS collection. | |
6076 if (t->is_ConcurrentGC_thread()) { | |
6077 assert(_collectorState == InitialMarking || | |
6078 _collectorState == FinalMarking, | |
6079 "Should be a stop-world phase"); | |
6080 // The CMS thread should be holding the CMS_token. | |
6081 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
6082 "Potential interference with concurrently " | |
6083 "executing VM thread"); | |
6084 } | |
6085 } | |
6086 } | |
6087 #endif | |
6088 | |
6089 void CMSCollector::sweep(bool asynch) { | |
6090 assert(_collectorState == Sweeping, "just checking"); | |
6091 check_correct_thread_executing(); | |
6092 verify_work_stacks_empty(); | |
6093 verify_overflow_empty(); | |
1145
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
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1085
diff
changeset
|
6094 increment_sweep_count(); |
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
parents:
3293
diff
changeset
|
6095 TraceCMSMemoryManagerStats tms(_collectorState,GenCollectedHeap::heap()->gc_cause()); |
1703
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
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1579
diff
changeset
|
6096 |
1145
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
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parents:
1085
diff
changeset
|
6097 _inter_sweep_timer.stop(); |
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6631166: CMS: better heuristics when combatting fragmentation
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diff
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|
6098 _inter_sweep_estimate.sample(_inter_sweep_timer.seconds()); |
0 | 6099 size_policy()->avg_cms_free_at_sweep()->sample(_cmsGen->free()); |
6100 | |
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6101 assert(!_intra_sweep_timer.is_active(), "Should not be active"); |
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6102 _intra_sweep_timer.reset(); |
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6103 _intra_sweep_timer.start(); |
0 | 6104 if (asynch) { |
6105 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
6106 CMSPhaseAccounting pa(this, "sweep", !PrintGCDetails); | |
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6107 // First sweep the old gen |
0 | 6108 { |
6109 CMSTokenSyncWithLocks ts(true, _cmsGen->freelistLock(), | |
6110 bitMapLock()); | |
6111 sweepWork(_cmsGen, asynch); | |
6112 } | |
6113 | |
6114 // Update Universe::_heap_*_at_gc figures. | |
6115 // We need all the free list locks to make the abstract state | |
6116 // transition from Sweeping to Resetting. See detailed note | |
6117 // further below. | |
6118 { | |
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6119 CMSTokenSyncWithLocks ts(true, _cmsGen->freelistLock()); |
0 | 6120 // Update heap occupancy information which is used as |
6121 // input to soft ref clearing policy at the next gc. | |
6122 Universe::update_heap_info_at_gc(); | |
6123 _collectorState = Resizing; | |
6124 } | |
6125 } else { | |
6126 // already have needed locks | |
6127 sweepWork(_cmsGen, asynch); | |
6128 // Update heap occupancy information which is used as | |
6129 // input to soft ref clearing policy at the next gc. | |
6130 Universe::update_heap_info_at_gc(); | |
6131 _collectorState = Resizing; | |
6132 } | |
6133 verify_work_stacks_empty(); | |
6134 verify_overflow_empty(); | |
6135 | |
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6136 if (should_unload_classes()) { |
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6137 ClassLoaderDataGraph::purge(); |
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6138 } |
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6139 |
1145
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6140 _intra_sweep_timer.stop(); |
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6141 _intra_sweep_estimate.sample(_intra_sweep_timer.seconds()); |
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6142 |
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6143 _inter_sweep_timer.reset(); |
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6144 _inter_sweep_timer.start(); |
0 | 6145 |
4911 | 6146 // We need to use a monotonically non-deccreasing time in ms |
6147 // or we will see time-warp warnings and os::javaTimeMillis() | |
6148 // does not guarantee monotonicity. | |
6149 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; | |
6150 update_time_of_last_gc(now); | |
0 | 6151 |
6152 // NOTE on abstract state transitions: | |
6153 // Mutators allocate-live and/or mark the mod-union table dirty | |
6154 // based on the state of the collection. The former is done in | |
6155 // the interval [Marking, Sweeping] and the latter in the interval | |
6156 // [Marking, Sweeping). Thus the transitions into the Marking state | |
6157 // and out of the Sweeping state must be synchronously visible | |
6158 // globally to the mutators. | |
6159 // The transition into the Marking state happens with the world | |
6160 // stopped so the mutators will globally see it. Sweeping is | |
6161 // done asynchronously by the background collector so the transition | |
6162 // from the Sweeping state to the Resizing state must be done | |
6163 // under the freelistLock (as is the check for whether to | |
6164 // allocate-live and whether to dirty the mod-union table). | |
6165 assert(_collectorState == Resizing, "Change of collector state to" | |
6166 " Resizing must be done under the freelistLocks (plural)"); | |
6167 | |
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6168 // Now that sweeping has been completed, we clear |
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6169 // the incremental_collection_failed flag, |
0 | 6170 // thus inviting a younger gen collection to promote into |
6171 // this generation. If such a promotion may still fail, | |
6172 // the flag will be set again when a young collection is | |
6173 // attempted. | |
6174 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
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6175 gch->clear_incremental_collection_failed(); // Worth retrying as fresh space may have been freed up |
0 | 6176 gch->update_full_collections_completed(_collection_count_start); |
6177 } | |
6178 | |
6179 // FIX ME!!! Looks like this belongs in CFLSpace, with | |
6180 // CMSGen merely delegating to it. | |
6181 void ConcurrentMarkSweepGeneration::setNearLargestChunk() { | |
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6182 double nearLargestPercent = FLSLargestBlockCoalesceProximity; |
0 | 6183 HeapWord* minAddr = _cmsSpace->bottom(); |
6184 HeapWord* largestAddr = | |
6028
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6185 (HeapWord*) _cmsSpace->dictionary()->find_largest_dict(); |
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6186 if (largestAddr == NULL) { |
0 | 6187 // The dictionary appears to be empty. In this case |
6188 // try to coalesce at the end of the heap. | |
6189 largestAddr = _cmsSpace->end(); | |
6190 } | |
6191 size_t largestOffset = pointer_delta(largestAddr, minAddr); | |
6192 size_t nearLargestOffset = | |
6193 (size_t)((double)largestOffset * nearLargestPercent) - MinChunkSize; | |
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6194 if (PrintFLSStatistics != 0) { |
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6195 gclog_or_tty->print_cr( |
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6196 "CMS: Large Block: " PTR_FORMAT ";" |
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6197 " Proximity: " PTR_FORMAT " -> " PTR_FORMAT, |
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6198 largestAddr, |
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6199 _cmsSpace->nearLargestChunk(), minAddr + nearLargestOffset); |
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6200 } |
0 | 6201 _cmsSpace->set_nearLargestChunk(minAddr + nearLargestOffset); |
6202 } | |
6203 | |
6204 bool ConcurrentMarkSweepGeneration::isNearLargestChunk(HeapWord* addr) { | |
6205 return addr >= _cmsSpace->nearLargestChunk(); | |
6206 } | |
6207 | |
6208 FreeChunk* ConcurrentMarkSweepGeneration::find_chunk_at_end() { | |
6209 return _cmsSpace->find_chunk_at_end(); | |
6210 } | |
6211 | |
6212 void ConcurrentMarkSweepGeneration::update_gc_stats(int current_level, | |
6213 bool full) { | |
6214 // The next lower level has been collected. Gather any statistics | |
6215 // that are of interest at this point. | |
6216 if (!full && (current_level + 1) == level()) { | |
6217 // Gather statistics on the young generation collection. | |
6218 collector()->stats().record_gc0_end(used()); | |
6219 } | |
6220 } | |
6221 | |
6222 CMSAdaptiveSizePolicy* ConcurrentMarkSweepGeneration::size_policy() { | |
6223 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
6224 assert(gch->kind() == CollectedHeap::GenCollectedHeap, | |
6225 "Wrong type of heap"); | |
6226 CMSAdaptiveSizePolicy* sp = (CMSAdaptiveSizePolicy*) | |
6227 gch->gen_policy()->size_policy(); | |
6228 assert(sp->is_gc_cms_adaptive_size_policy(), | |
6229 "Wrong type of size policy"); | |
6230 return sp; | |
6231 } | |
6232 | |
6233 void ConcurrentMarkSweepGeneration::rotate_debug_collection_type() { | |
6234 if (PrintGCDetails && Verbose) { | |
6235 gclog_or_tty->print("Rotate from %d ", _debug_collection_type); | |
6236 } | |
6237 _debug_collection_type = (CollectionTypes) (_debug_collection_type + 1); | |
6238 _debug_collection_type = | |
6239 (CollectionTypes) (_debug_collection_type % Unknown_collection_type); | |
6240 if (PrintGCDetails && Verbose) { | |
6241 gclog_or_tty->print_cr("to %d ", _debug_collection_type); | |
6242 } | |
6243 } | |
6244 | |
6245 void CMSCollector::sweepWork(ConcurrentMarkSweepGeneration* gen, | |
6246 bool asynch) { | |
6247 // We iterate over the space(s) underlying this generation, | |
6248 // checking the mark bit map to see if the bits corresponding | |
6249 // to specific blocks are marked or not. Blocks that are | |
6250 // marked are live and are not swept up. All remaining blocks | |
6251 // are swept up, with coalescing on-the-fly as we sweep up | |
6252 // contiguous free and/or garbage blocks: | |
6253 // We need to ensure that the sweeper synchronizes with allocators | |
6254 // and stop-the-world collectors. In particular, the following | |
6255 // locks are used: | |
6256 // . CMS token: if this is held, a stop the world collection cannot occur | |
6257 // . freelistLock: if this is held no allocation can occur from this | |
6258 // generation by another thread | |
6259 // . bitMapLock: if this is held, no other thread can access or update | |
6260 // | |
6261 | |
6262 // Note that we need to hold the freelistLock if we use | |
6263 // block iterate below; else the iterator might go awry if | |
6264 // a mutator (or promotion) causes block contents to change | |
6265 // (for instance if the allocator divvies up a block). | |
6266 // If we hold the free list lock, for all practical purposes | |
6267 // young generation GC's can't occur (they'll usually need to | |
6268 // promote), so we might as well prevent all young generation | |
6269 // GC's while we do a sweeping step. For the same reason, we might | |
6270 // as well take the bit map lock for the entire duration | |
6271 | |
6272 // check that we hold the requisite locks | |
6273 assert(have_cms_token(), "Should hold cms token"); | |
6274 assert( (asynch && ConcurrentMarkSweepThread::cms_thread_has_cms_token()) | |
6275 || (!asynch && ConcurrentMarkSweepThread::vm_thread_has_cms_token()), | |
6276 "Should possess CMS token to sweep"); | |
6277 assert_lock_strong(gen->freelistLock()); | |
6278 assert_lock_strong(bitMapLock()); | |
6279 | |
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6280 assert(!_inter_sweep_timer.is_active(), "Was switched off in an outer context"); |
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6281 assert(_intra_sweep_timer.is_active(), "Was switched on in an outer context"); |
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6282 gen->cmsSpace()->beginSweepFLCensus((float)(_inter_sweep_timer.seconds()), |
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6283 _inter_sweep_estimate.padded_average(), |
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6284 _intra_sweep_estimate.padded_average()); |
0 | 6285 gen->setNearLargestChunk(); |
6286 | |
6287 { | |
6288 SweepClosure sweepClosure(this, gen, &_markBitMap, | |
6289 CMSYield && asynch); | |
6290 gen->cmsSpace()->blk_iterate_careful(&sweepClosure); | |
6291 // We need to free-up/coalesce garbage/blocks from a | |
6292 // co-terminal free run. This is done in the SweepClosure | |
6293 // destructor; so, do not remove this scope, else the | |
6294 // end-of-sweep-census below will be off by a little bit. | |
6295 } | |
6296 gen->cmsSpace()->sweep_completed(); | |
1145
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6297 gen->cmsSpace()->endSweepFLCensus(sweep_count()); |
94
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6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
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|
6298 if (should_unload_classes()) { // unloaded classes this cycle, |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
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|
6299 _concurrent_cycles_since_last_unload = 0; // ... reset count |
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6300 } else { // did not unload classes, |
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|
6301 _concurrent_cycles_since_last_unload++; // ... increment count |
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|
6302 } |
0 | 6303 } |
6304 | |
6305 // Reset CMS data structures (for now just the marking bit map) | |
6306 // preparatory for the next cycle. | |
6307 void CMSCollector::reset(bool asynch) { | |
6308 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
6309 CMSAdaptiveSizePolicy* sp = size_policy(); | |
6310 AdaptiveSizePolicyOutput(sp, gch->total_collections()); | |
6311 if (asynch) { | |
6312 CMSTokenSyncWithLocks ts(true, bitMapLock()); | |
6313 | |
6314 // If the state is not "Resetting", the foreground thread | |
6315 // has done a collection and the resetting. | |
6316 if (_collectorState != Resetting) { | |
6317 assert(_collectorState == Idling, "The state should only change" | |
6318 " because the foreground collector has finished the collection"); | |
6319 return; | |
6320 } | |
6321 | |
6322 // Clear the mark bitmap (no grey objects to start with) | |
6323 // for the next cycle. | |
6324 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
6325 CMSPhaseAccounting cmspa(this, "reset", !PrintGCDetails); | |
6326 | |
6327 HeapWord* curAddr = _markBitMap.startWord(); | |
6328 while (curAddr < _markBitMap.endWord()) { | |
6329 size_t remaining = pointer_delta(_markBitMap.endWord(), curAddr); | |
6330 MemRegion chunk(curAddr, MIN2(CMSBitMapYieldQuantum, remaining)); | |
6331 _markBitMap.clear_large_range(chunk); | |
6332 if (ConcurrentMarkSweepThread::should_yield() && | |
6333 !foregroundGCIsActive() && | |
6334 CMSYield) { | |
6335 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
6336 "CMS thread should hold CMS token"); | |
6337 assert_lock_strong(bitMapLock()); | |
6338 bitMapLock()->unlock(); | |
6339 ConcurrentMarkSweepThread::desynchronize(true); | |
6340 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
6341 stopTimer(); | |
6342 if (PrintCMSStatistics != 0) { | |
6343 incrementYields(); | |
6344 } | |
6345 icms_wait(); | |
6346 | |
6347 // See the comment in coordinator_yield() | |
6348 for (unsigned i = 0; i < CMSYieldSleepCount && | |
113
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6349 ConcurrentMarkSweepThread::should_yield() && |
ba764ed4b6f2
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6350 !CMSCollector::foregroundGCIsActive(); ++i) { |
0 | 6351 os::sleep(Thread::current(), 1, false); |
6352 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
6353 } | |
6354 | |
6355 ConcurrentMarkSweepThread::synchronize(true); | |
6356 bitMapLock()->lock_without_safepoint_check(); | |
6357 startTimer(); | |
6358 } | |
6359 curAddr = chunk.end(); | |
6360 } | |
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6361 // A successful mostly concurrent collection has been done. |
0bfd3fb24150
6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
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6362 // Because only the full (i.e., concurrent mode failure) collections |
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6363 // are being measured for gc overhead limits, clean the "near" flag |
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6364 // and count. |
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|
6365 sp->reset_gc_overhead_limit_count(); |
0 | 6366 _collectorState = Idling; |
6367 } else { | |
6368 // already have the lock | |
6369 assert(_collectorState == Resetting, "just checking"); | |
6370 assert_lock_strong(bitMapLock()); | |
6371 _markBitMap.clear_all(); | |
6372 _collectorState = Idling; | |
6373 } | |
6374 | |
6375 // Stop incremental mode after a cycle completes, so that any future cycles | |
6376 // are triggered by allocation. | |
6377 stop_icms(); | |
6378 | |
6379 NOT_PRODUCT( | |
6380 if (RotateCMSCollectionTypes) { | |
6381 _cmsGen->rotate_debug_collection_type(); | |
6382 } | |
6383 ) | |
6384 } | |
6385 | |
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6386 void CMSCollector::do_CMS_operation(CMS_op_type op, GCCause::Cause gc_cause) { |
0 | 6387 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps); |
6388 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
6064
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|
6389 TraceTime t(GCCauseString("GC", gc_cause), PrintGC, !PrintGCDetails, gclog_or_tty); |
0 | 6390 TraceCollectorStats tcs(counters()); |
6391 | |
6392 switch (op) { | |
6393 case CMS_op_checkpointRootsInitial: { | |
2125
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|
6394 SvcGCMarker sgcm(SvcGCMarker::OTHER); |
0 | 6395 checkpointRootsInitial(true); // asynch |
6396 if (PrintGC) { | |
6397 _cmsGen->printOccupancy("initial-mark"); | |
6398 } | |
6399 break; | |
6400 } | |
6401 case CMS_op_checkpointRootsFinal: { | |
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6402 SvcGCMarker sgcm(SvcGCMarker::OTHER); |
0 | 6403 checkpointRootsFinal(true, // asynch |
6404 false, // !clear_all_soft_refs | |
6405 false); // !init_mark_was_synchronous | |
6406 if (PrintGC) { | |
6407 _cmsGen->printOccupancy("remark"); | |
6408 } | |
6409 break; | |
6410 } | |
6411 default: | |
6412 fatal("No such CMS_op"); | |
6413 } | |
6414 } | |
6415 | |
6416 #ifndef PRODUCT | |
6417 size_t const CMSCollector::skip_header_HeapWords() { | |
6418 return FreeChunk::header_size(); | |
6419 } | |
6420 | |
6421 // Try and collect here conditions that should hold when | |
6422 // CMS thread is exiting. The idea is that the foreground GC | |
6423 // thread should not be blocked if it wants to terminate | |
6424 // the CMS thread and yet continue to run the VM for a while | |
6425 // after that. | |
6426 void CMSCollector::verify_ok_to_terminate() const { | |
6427 assert(Thread::current()->is_ConcurrentGC_thread(), | |
6428 "should be called by CMS thread"); | |
6429 assert(!_foregroundGCShouldWait, "should be false"); | |
6430 // We could check here that all the various low-level locks | |
6431 // are not held by the CMS thread, but that is overkill; see | |
6432 // also CMSThread::verify_ok_to_terminate() where the CGC_lock | |
6433 // is checked. | |
6434 } | |
6435 #endif | |
6436 | |
6437 size_t CMSCollector::block_size_using_printezis_bits(HeapWord* addr) const { | |
453
c96030fff130
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|
6438 assert(_markBitMap.isMarked(addr) && _markBitMap.isMarked(addr + 1), |
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6439 "missing Printezis mark?"); |
0 | 6440 HeapWord* nextOneAddr = _markBitMap.getNextMarkedWordAddress(addr + 2); |
6441 size_t size = pointer_delta(nextOneAddr + 1, addr); | |
6442 assert(size == CompactibleFreeListSpace::adjustObjectSize(size), | |
6443 "alignment problem"); | |
6444 assert(size >= 3, "Necessary for Printezis marks to work"); | |
6445 return size; | |
6446 } | |
6447 | |
6448 // A variant of the above (block_size_using_printezis_bits()) except | |
6449 // that we return 0 if the P-bits are not yet set. | |
6450 size_t CMSCollector::block_size_if_printezis_bits(HeapWord* addr) const { | |
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6451 if (_markBitMap.isMarked(addr + 1)) { |
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6452 assert(_markBitMap.isMarked(addr), "P-bit can be set only for marked objects"); |
0 | 6453 HeapWord* nextOneAddr = _markBitMap.getNextMarkedWordAddress(addr + 2); |
6454 size_t size = pointer_delta(nextOneAddr + 1, addr); | |
6455 assert(size == CompactibleFreeListSpace::adjustObjectSize(size), | |
6456 "alignment problem"); | |
6457 assert(size >= 3, "Necessary for Printezis marks to work"); | |
6458 return size; | |
2226
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6459 } |
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6460 return 0; |
0 | 6461 } |
6462 | |
6463 HeapWord* CMSCollector::next_card_start_after_block(HeapWord* addr) const { | |
6464 size_t sz = 0; | |
6465 oop p = (oop)addr; | |
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6466 if (p->klass_or_null() != NULL) { |
0 | 6467 sz = CompactibleFreeListSpace::adjustObjectSize(p->size()); |
6468 } else { | |
6469 sz = block_size_using_printezis_bits(addr); | |
6470 } | |
6471 assert(sz > 0, "size must be nonzero"); | |
6472 HeapWord* next_block = addr + sz; | |
6473 HeapWord* next_card = (HeapWord*)round_to((uintptr_t)next_block, | |
6474 CardTableModRefBS::card_size); | |
6475 assert(round_down((uintptr_t)addr, CardTableModRefBS::card_size) < | |
6476 round_down((uintptr_t)next_card, CardTableModRefBS::card_size), | |
6477 "must be different cards"); | |
6478 return next_card; | |
6479 } | |
6480 | |
6481 | |
6482 // CMS Bit Map Wrapper ///////////////////////////////////////// | |
6483 | |
6484 // Construct a CMS bit map infrastructure, but don't create the | |
6485 // bit vector itself. That is done by a separate call CMSBitMap::allocate() | |
6486 // further below. | |
6487 CMSBitMap::CMSBitMap(int shifter, int mutex_rank, const char* mutex_name): | |
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6488 _bm(), |
0 | 6489 _shifter(shifter), |
6490 _lock(mutex_rank >= 0 ? new Mutex(mutex_rank, mutex_name, true) : NULL) | |
6491 { | |
6492 _bmStartWord = 0; | |
6493 _bmWordSize = 0; | |
6494 } | |
6495 | |
6496 bool CMSBitMap::allocate(MemRegion mr) { | |
6497 _bmStartWord = mr.start(); | |
6498 _bmWordSize = mr.word_size(); | |
6499 ReservedSpace brs(ReservedSpace::allocation_align_size_up( | |
6500 (_bmWordSize >> (_shifter + LogBitsPerByte)) + 1)); | |
6501 if (!brs.is_reserved()) { | |
6502 warning("CMS bit map allocation failure"); | |
6503 return false; | |
6504 } | |
6505 // For now we'll just commit all of the bit map up fromt. | |
6506 // Later on we'll try to be more parsimonious with swap. | |
6507 if (!_virtual_space.initialize(brs, brs.size())) { | |
6508 warning("CMS bit map backing store failure"); | |
6509 return false; | |
6510 } | |
6511 assert(_virtual_space.committed_size() == brs.size(), | |
6512 "didn't reserve backing store for all of CMS bit map?"); | |
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6513 _bm.set_map((BitMap::bm_word_t*)_virtual_space.low()); |
0 | 6514 assert(_virtual_space.committed_size() << (_shifter + LogBitsPerByte) >= |
6515 _bmWordSize, "inconsistency in bit map sizing"); | |
6516 _bm.set_size(_bmWordSize >> _shifter); | |
6517 | |
6518 // bm.clear(); // can we rely on getting zero'd memory? verify below | |
6519 assert(isAllClear(), | |
6520 "Expected zero'd memory from ReservedSpace constructor"); | |
6521 assert(_bm.size() == heapWordDiffToOffsetDiff(sizeInWords()), | |
6522 "consistency check"); | |
6523 return true; | |
6524 } | |
6525 | |
6526 void CMSBitMap::dirty_range_iterate_clear(MemRegion mr, MemRegionClosure* cl) { | |
6527 HeapWord *next_addr, *end_addr, *last_addr; | |
6528 assert_locked(); | |
6529 assert(covers(mr), "out-of-range error"); | |
6530 // XXX assert that start and end are appropriately aligned | |
6531 for (next_addr = mr.start(), end_addr = mr.end(); | |
6532 next_addr < end_addr; next_addr = last_addr) { | |
6533 MemRegion dirty_region = getAndClearMarkedRegion(next_addr, end_addr); | |
6534 last_addr = dirty_region.end(); | |
6535 if (!dirty_region.is_empty()) { | |
6536 cl->do_MemRegion(dirty_region); | |
6537 } else { | |
6538 assert(last_addr == end_addr, "program logic"); | |
6539 return; | |
6540 } | |
6541 } | |
6542 } | |
6543 | |
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6544 void CMSBitMap::print_on_error(outputStream* st, const char* prefix) const { |
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6545 _bm.print_on_error(st, prefix); |
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6546 } |
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6547 |
0 | 6548 #ifndef PRODUCT |
6549 void CMSBitMap::assert_locked() const { | |
6550 CMSLockVerifier::assert_locked(lock()); | |
6551 } | |
6552 | |
6553 bool CMSBitMap::covers(MemRegion mr) const { | |
6554 // assert(_bm.map() == _virtual_space.low(), "map inconsistency"); | |
6555 assert((size_t)_bm.size() == (_bmWordSize >> _shifter), | |
6556 "size inconsistency"); | |
6557 return (mr.start() >= _bmStartWord) && | |
6558 (mr.end() <= endWord()); | |
6559 } | |
6560 | |
6561 bool CMSBitMap::covers(HeapWord* start, size_t size) const { | |
6562 return (start >= _bmStartWord && (start + size) <= endWord()); | |
6563 } | |
6564 | |
6565 void CMSBitMap::verifyNoOneBitsInRange(HeapWord* left, HeapWord* right) { | |
6566 // verify that there are no 1 bits in the interval [left, right) | |
6567 FalseBitMapClosure falseBitMapClosure; | |
6568 iterate(&falseBitMapClosure, left, right); | |
6569 } | |
6570 | |
6571 void CMSBitMap::region_invariant(MemRegion mr) | |
6572 { | |
6573 assert_locked(); | |
6574 // mr = mr.intersection(MemRegion(_bmStartWord, _bmWordSize)); | |
6575 assert(!mr.is_empty(), "unexpected empty region"); | |
6576 assert(covers(mr), "mr should be covered by bit map"); | |
6577 // convert address range into offset range | |
6578 size_t start_ofs = heapWordToOffset(mr.start()); | |
6579 // Make sure that end() is appropriately aligned | |
6580 assert(mr.end() == (HeapWord*)round_to((intptr_t)mr.end(), | |
6581 (1 << (_shifter+LogHeapWordSize))), | |
6582 "Misaligned mr.end()"); | |
6583 size_t end_ofs = heapWordToOffset(mr.end()); | |
6584 assert(end_ofs > start_ofs, "Should mark at least one bit"); | |
6585 } | |
6586 | |
6587 #endif | |
6588 | |
6589 bool CMSMarkStack::allocate(size_t size) { | |
6590 // allocate a stack of the requisite depth | |
6591 ReservedSpace rs(ReservedSpace::allocation_align_size_up( | |
6592 size * sizeof(oop))); | |
6593 if (!rs.is_reserved()) { | |
6594 warning("CMSMarkStack allocation failure"); | |
6595 return false; | |
6596 } | |
6597 if (!_virtual_space.initialize(rs, rs.size())) { | |
6598 warning("CMSMarkStack backing store failure"); | |
6599 return false; | |
6600 } | |
6601 assert(_virtual_space.committed_size() == rs.size(), | |
6602 "didn't reserve backing store for all of CMS stack?"); | |
6603 _base = (oop*)(_virtual_space.low()); | |
6604 _index = 0; | |
6605 _capacity = size; | |
6606 NOT_PRODUCT(_max_depth = 0); | |
6607 return true; | |
6608 } | |
6609 | |
6610 // XXX FIX ME !!! In the MT case we come in here holding a | |
6611 // leaf lock. For printing we need to take a further lock | |
6612 // which has lower rank. We need to recallibrate the two | |
6613 // lock-ranks involved in order to be able to rpint the | |
6614 // messages below. (Or defer the printing to the caller. | |
6615 // For now we take the expedient path of just disabling the | |
6616 // messages for the problematic case.) | |
6617 void CMSMarkStack::expand() { | |
1284 | 6618 assert(_capacity <= MarkStackSizeMax, "stack bigger than permitted"); |
6619 if (_capacity == MarkStackSizeMax) { | |
0 | 6620 if (_hit_limit++ == 0 && !CMSConcurrentMTEnabled && PrintGCDetails) { |
6621 // We print a warning message only once per CMS cycle. | |
6622 gclog_or_tty->print_cr(" (benign) Hit CMSMarkStack max size limit"); | |
6623 } | |
6624 return; | |
6625 } | |
6626 // Double capacity if possible | |
1284 | 6627 size_t new_capacity = MIN2(_capacity*2, MarkStackSizeMax); |
0 | 6628 // Do not give up existing stack until we have managed to |
6629 // get the double capacity that we desired. | |
6630 ReservedSpace rs(ReservedSpace::allocation_align_size_up( | |
6631 new_capacity * sizeof(oop))); | |
6632 if (rs.is_reserved()) { | |
6633 // Release the backing store associated with old stack | |
6634 _virtual_space.release(); | |
6635 // Reinitialize virtual space for new stack | |
6636 if (!_virtual_space.initialize(rs, rs.size())) { | |
6637 fatal("Not enough swap for expanded marking stack"); | |
6638 } | |
6639 _base = (oop*)(_virtual_space.low()); | |
6640 _index = 0; | |
6641 _capacity = new_capacity; | |
6642 } else if (_failed_double++ == 0 && !CMSConcurrentMTEnabled && PrintGCDetails) { | |
6643 // Failed to double capacity, continue; | |
6644 // we print a detail message only once per CMS cycle. | |
6645 gclog_or_tty->print(" (benign) Failed to expand marking stack from "SIZE_FORMAT"K to " | |
6646 SIZE_FORMAT"K", | |
6647 _capacity / K, new_capacity / K); | |
6648 } | |
6649 } | |
6650 | |
6651 | |
6652 // Closures | |
6653 // XXX: there seems to be a lot of code duplication here; | |
6654 // should refactor and consolidate common code. | |
6655 | |
6656 // This closure is used to mark refs into the CMS generation in | |
6657 // the CMS bit map. Called at the first checkpoint. This closure | |
6658 // assumes that we do not need to re-mark dirty cards; if the CMS | |
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6659 // generation on which this is used is not an oldest |
0 | 6660 // generation then this will lose younger_gen cards! |
6661 | |
6662 MarkRefsIntoClosure::MarkRefsIntoClosure( | |
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6663 MemRegion span, CMSBitMap* bitMap): |
0 | 6664 _span(span), |
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6665 _bitMap(bitMap) |
0 | 6666 { |
6667 assert(_ref_processor == NULL, "deliberately left NULL"); | |
6668 assert(_bitMap->covers(_span), "_bitMap/_span mismatch"); | |
6669 } | |
6670 | |
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6671 void MarkRefsIntoClosure::do_oop(oop obj) { |
0 | 6672 // if p points into _span, then mark corresponding bit in _markBitMap |
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6673 assert(obj->is_oop(), "expected an oop"); |
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6674 HeapWord* addr = (HeapWord*)obj; |
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6675 if (_span.contains(addr)) { |
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6676 // this should be made more efficient |
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6677 _bitMap->mark(addr); |
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6678 } |
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6679 } |
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6680 |
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6681 void MarkRefsIntoClosure::do_oop(oop* p) { MarkRefsIntoClosure::do_oop_work(p); } |
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6682 void MarkRefsIntoClosure::do_oop(narrowOop* p) { MarkRefsIntoClosure::do_oop_work(p); } |
0 | 6683 |
6684 // A variant of the above, used for CMS marking verification. | |
6685 MarkRefsIntoVerifyClosure::MarkRefsIntoVerifyClosure( | |
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6686 MemRegion span, CMSBitMap* verification_bm, CMSBitMap* cms_bm): |
0 | 6687 _span(span), |
6688 _verification_bm(verification_bm), | |
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6689 _cms_bm(cms_bm) |
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6690 { |
0 | 6691 assert(_ref_processor == NULL, "deliberately left NULL"); |
6692 assert(_verification_bm->covers(_span), "_verification_bm/_span mismatch"); | |
6693 } | |
6694 | |
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6695 void MarkRefsIntoVerifyClosure::do_oop(oop obj) { |
0 | 6696 // if p points into _span, then mark corresponding bit in _markBitMap |
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6697 assert(obj->is_oop(), "expected an oop"); |
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6698 HeapWord* addr = (HeapWord*)obj; |
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6699 if (_span.contains(addr)) { |
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6700 _verification_bm->mark(addr); |
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6701 if (!_cms_bm->isMarked(addr)) { |
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6702 oop(addr)->print(); |
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6703 gclog_or_tty->print_cr(" (" INTPTR_FORMAT " should have been marked)", addr); |
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6704 fatal("... aborting"); |
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6705 } |
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6706 } |
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6707 } |
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6708 |
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6709 void MarkRefsIntoVerifyClosure::do_oop(oop* p) { MarkRefsIntoVerifyClosure::do_oop_work(p); } |
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6710 void MarkRefsIntoVerifyClosure::do_oop(narrowOop* p) { MarkRefsIntoVerifyClosure::do_oop_work(p); } |
0 | 6711 |
6712 ////////////////////////////////////////////////// | |
6713 // MarkRefsIntoAndScanClosure | |
6714 ////////////////////////////////////////////////// | |
6715 | |
6716 MarkRefsIntoAndScanClosure::MarkRefsIntoAndScanClosure(MemRegion span, | |
6717 ReferenceProcessor* rp, | |
6718 CMSBitMap* bit_map, | |
6719 CMSBitMap* mod_union_table, | |
6720 CMSMarkStack* mark_stack, | |
6721 CMSCollector* collector, | |
6722 bool should_yield, | |
6723 bool concurrent_precleaning): | |
6724 _collector(collector), | |
6725 _span(span), | |
6726 _bit_map(bit_map), | |
6727 _mark_stack(mark_stack), | |
6728 _pushAndMarkClosure(collector, span, rp, bit_map, mod_union_table, | |
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6729 mark_stack, concurrent_precleaning), |
0 | 6730 _yield(should_yield), |
6731 _concurrent_precleaning(concurrent_precleaning), | |
6732 _freelistLock(NULL) | |
6733 { | |
6734 _ref_processor = rp; | |
6735 assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL"); | |
6736 } | |
6737 | |
6738 // This closure is used to mark refs into the CMS generation at the | |
6739 // second (final) checkpoint, and to scan and transitively follow | |
6740 // the unmarked oops. It is also used during the concurrent precleaning | |
6741 // phase while scanning objects on dirty cards in the CMS generation. | |
6742 // The marks are made in the marking bit map and the marking stack is | |
6743 // used for keeping the (newly) grey objects during the scan. | |
6744 // The parallel version (Par_...) appears further below. | |
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6745 void MarkRefsIntoAndScanClosure::do_oop(oop obj) { |
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6746 if (obj != NULL) { |
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6747 assert(obj->is_oop(), "expected an oop"); |
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6748 HeapWord* addr = (HeapWord*)obj; |
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6749 assert(_mark_stack->isEmpty(), "pre-condition (eager drainage)"); |
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6750 assert(_collector->overflow_list_is_empty(), |
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6751 "overflow list should be empty"); |
0 | 6752 if (_span.contains(addr) && |
6753 !_bit_map->isMarked(addr)) { | |
6754 // mark bit map (object is now grey) | |
6755 _bit_map->mark(addr); | |
6756 // push on marking stack (stack should be empty), and drain the | |
6757 // stack by applying this closure to the oops in the oops popped | |
6758 // from the stack (i.e. blacken the grey objects) | |
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6759 bool res = _mark_stack->push(obj); |
0 | 6760 assert(res, "Should have space to push on empty stack"); |
6761 do { | |
6762 oop new_oop = _mark_stack->pop(); | |
6763 assert(new_oop != NULL && new_oop->is_oop(), "Expected an oop"); | |
6764 assert(_bit_map->isMarked((HeapWord*)new_oop), | |
6765 "only grey objects on this stack"); | |
6766 // iterate over the oops in this oop, marking and pushing | |
6767 // the ones in CMS heap (i.e. in _span). | |
6768 new_oop->oop_iterate(&_pushAndMarkClosure); | |
6769 // check if it's time to yield | |
6770 do_yield_check(); | |
6771 } while (!_mark_stack->isEmpty() || | |
6772 (!_concurrent_precleaning && take_from_overflow_list())); | |
6773 // if marking stack is empty, and we are not doing this | |
6774 // during precleaning, then check the overflow list | |
6775 } | |
6776 assert(_mark_stack->isEmpty(), "post-condition (eager drainage)"); | |
6777 assert(_collector->overflow_list_is_empty(), | |
6778 "overflow list was drained above"); | |
6779 // We could restore evacuated mark words, if any, used for | |
6780 // overflow list links here because the overflow list is | |
6781 // provably empty here. That would reduce the maximum | |
6782 // size requirements for preserved_{oop,mark}_stack. | |
6783 // But we'll just postpone it until we are all done | |
6784 // so we can just stream through. | |
6785 if (!_concurrent_precleaning && CMSOverflowEarlyRestoration) { | |
6786 _collector->restore_preserved_marks_if_any(); | |
6787 assert(_collector->no_preserved_marks(), "No preserved marks"); | |
6788 } | |
6789 assert(!CMSOverflowEarlyRestoration || _collector->no_preserved_marks(), | |
6790 "All preserved marks should have been restored above"); | |
6791 } | |
6792 } | |
6793 | |
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6794 void MarkRefsIntoAndScanClosure::do_oop(oop* p) { MarkRefsIntoAndScanClosure::do_oop_work(p); } |
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6795 void MarkRefsIntoAndScanClosure::do_oop(narrowOop* p) { MarkRefsIntoAndScanClosure::do_oop_work(p); } |
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6796 |
0 | 6797 void MarkRefsIntoAndScanClosure::do_yield_work() { |
6798 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
6799 "CMS thread should hold CMS token"); | |
6800 assert_lock_strong(_freelistLock); | |
6801 assert_lock_strong(_bit_map->lock()); | |
6802 // relinquish the free_list_lock and bitMaplock() | |
6803 _bit_map->lock()->unlock(); | |
6804 _freelistLock->unlock(); | |
6805 ConcurrentMarkSweepThread::desynchronize(true); | |
6806 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
6807 _collector->stopTimer(); | |
6808 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
6809 if (PrintCMSStatistics != 0) { | |
6810 _collector->incrementYields(); | |
6811 } | |
6812 _collector->icms_wait(); | |
6813 | |
6814 // See the comment in coordinator_yield() | |
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6815 for (unsigned i = 0; |
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6816 i < CMSYieldSleepCount && |
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6817 ConcurrentMarkSweepThread::should_yield() && |
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6818 !CMSCollector::foregroundGCIsActive(); |
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6819 ++i) { |
0 | 6820 os::sleep(Thread::current(), 1, false); |
6821 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
6822 } | |
6823 | |
6824 ConcurrentMarkSweepThread::synchronize(true); | |
6825 _freelistLock->lock_without_safepoint_check(); | |
6826 _bit_map->lock()->lock_without_safepoint_check(); | |
6827 _collector->startTimer(); | |
6828 } | |
6829 | |
6830 /////////////////////////////////////////////////////////// | |
6831 // Par_MarkRefsIntoAndScanClosure: a parallel version of | |
6832 // MarkRefsIntoAndScanClosure | |
6833 /////////////////////////////////////////////////////////// | |
6834 Par_MarkRefsIntoAndScanClosure::Par_MarkRefsIntoAndScanClosure( | |
6835 CMSCollector* collector, MemRegion span, ReferenceProcessor* rp, | |
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6836 CMSBitMap* bit_map, OopTaskQueue* work_queue): |
0 | 6837 _span(span), |
6838 _bit_map(bit_map), | |
6839 _work_queue(work_queue), | |
6840 _low_water_mark(MIN2((uint)(work_queue->max_elems()/4), | |
6841 (uint)(CMSWorkQueueDrainThreshold * ParallelGCThreads))), | |
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6842 _par_pushAndMarkClosure(collector, span, rp, bit_map, work_queue) |
0 | 6843 { |
6844 _ref_processor = rp; | |
6845 assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL"); | |
6846 } | |
6847 | |
6848 // This closure is used to mark refs into the CMS generation at the | |
6849 // second (final) checkpoint, and to scan and transitively follow | |
6850 // the unmarked oops. The marks are made in the marking bit map and | |
6851 // the work_queue is used for keeping the (newly) grey objects during | |
6852 // the scan phase whence they are also available for stealing by parallel | |
6853 // threads. Since the marking bit map is shared, updates are | |
6854 // synchronized (via CAS). | |
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6855 void Par_MarkRefsIntoAndScanClosure::do_oop(oop obj) { |
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6856 if (obj != NULL) { |
0 | 6857 // Ignore mark word because this could be an already marked oop |
6858 // that may be chained at the end of the overflow list. | |
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6859 assert(obj->is_oop(true), "expected an oop"); |
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6860 HeapWord* addr = (HeapWord*)obj; |
0 | 6861 if (_span.contains(addr) && |
6862 !_bit_map->isMarked(addr)) { | |
6863 // mark bit map (object will become grey): | |
6864 // It is possible for several threads to be | |
6865 // trying to "claim" this object concurrently; | |
6866 // the unique thread that succeeds in marking the | |
6867 // object first will do the subsequent push on | |
6868 // to the work queue (or overflow list). | |
6869 if (_bit_map->par_mark(addr)) { | |
6870 // push on work_queue (which may not be empty), and trim the | |
6871 // queue to an appropriate length by applying this closure to | |
6872 // the oops in the oops popped from the stack (i.e. blacken the | |
6873 // grey objects) | |
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6874 bool res = _work_queue->push(obj); |
0 | 6875 assert(res, "Low water mark should be less than capacity?"); |
6876 trim_queue(_low_water_mark); | |
6877 } // Else, another thread claimed the object | |
6878 } | |
6879 } | |
6880 } | |
6881 | |
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6882 void Par_MarkRefsIntoAndScanClosure::do_oop(oop* p) { Par_MarkRefsIntoAndScanClosure::do_oop_work(p); } |
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6883 void Par_MarkRefsIntoAndScanClosure::do_oop(narrowOop* p) { Par_MarkRefsIntoAndScanClosure::do_oop_work(p); } |
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6884 |
0 | 6885 // This closure is used to rescan the marked objects on the dirty cards |
6886 // in the mod union table and the card table proper. | |
6887 size_t ScanMarkedObjectsAgainCarefullyClosure::do_object_careful_m( | |
6888 oop p, MemRegion mr) { | |
6889 | |
6890 size_t size = 0; | |
6891 HeapWord* addr = (HeapWord*)p; | |
6892 DEBUG_ONLY(_collector->verify_work_stacks_empty();) | |
6893 assert(_span.contains(addr), "we are scanning the CMS generation"); | |
6894 // check if it's time to yield | |
6895 if (do_yield_check()) { | |
6896 // We yielded for some foreground stop-world work, | |
6897 // and we have been asked to abort this ongoing preclean cycle. | |
6898 return 0; | |
6899 } | |
6900 if (_bitMap->isMarked(addr)) { | |
6901 // it's marked; is it potentially uninitialized? | |
187 | 6902 if (p->klass_or_null() != NULL) { |
0 | 6903 // an initialized object; ignore mark word in verification below |
6904 // since we are running concurrent with mutators | |
6905 assert(p->is_oop(true), "should be an oop"); | |
6906 if (p->is_objArray()) { | |
6907 // objArrays are precisely marked; restrict scanning | |
6908 // to dirty cards only. | |
187 | 6909 size = CompactibleFreeListSpace::adjustObjectSize( |
6910 p->oop_iterate(_scanningClosure, mr)); | |
0 | 6911 } else { |
6912 // A non-array may have been imprecisely marked; we need | |
6913 // to scan object in its entirety. | |
6914 size = CompactibleFreeListSpace::adjustObjectSize( | |
6915 p->oop_iterate(_scanningClosure)); | |
6916 } | |
9152 | 6917 #ifdef ASSERT |
0 | 6918 size_t direct_size = |
6919 CompactibleFreeListSpace::adjustObjectSize(p->size()); | |
6920 assert(size == direct_size, "Inconsistency in size"); | |
6921 assert(size >= 3, "Necessary for Printezis marks to work"); | |
6922 if (!_bitMap->isMarked(addr+1)) { | |
6923 _bitMap->verifyNoOneBitsInRange(addr+2, addr+size); | |
6924 } else { | |
6925 _bitMap->verifyNoOneBitsInRange(addr+2, addr+size-1); | |
6926 assert(_bitMap->isMarked(addr+size-1), | |
6927 "inconsistent Printezis mark"); | |
6928 } | |
9152 | 6929 #endif // ASSERT |
0 | 6930 } else { |
6931 // an unitialized object | |
6932 assert(_bitMap->isMarked(addr+1), "missing Printezis mark?"); | |
6933 HeapWord* nextOneAddr = _bitMap->getNextMarkedWordAddress(addr + 2); | |
6934 size = pointer_delta(nextOneAddr + 1, addr); | |
6935 assert(size == CompactibleFreeListSpace::adjustObjectSize(size), | |
6936 "alignment problem"); | |
6937 // Note that pre-cleaning needn't redirty the card. OopDesc::set_klass() | |
6938 // will dirty the card when the klass pointer is installed in the | |
6939 // object (signalling the completion of initialization). | |
6940 } | |
6941 } else { | |
6942 // Either a not yet marked object or an uninitialized object | |
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6943 if (p->klass_or_null() == NULL) { |
0 | 6944 // An uninitialized object, skip to the next card, since |
6945 // we may not be able to read its P-bits yet. | |
6946 assert(size == 0, "Initial value"); | |
6947 } else { | |
6948 // An object not (yet) reached by marking: we merely need to | |
6949 // compute its size so as to go look at the next block. | |
6950 assert(p->is_oop(true), "should be an oop"); | |
6951 size = CompactibleFreeListSpace::adjustObjectSize(p->size()); | |
6952 } | |
6953 } | |
6954 DEBUG_ONLY(_collector->verify_work_stacks_empty();) | |
6955 return size; | |
6956 } | |
6957 | |
6958 void ScanMarkedObjectsAgainCarefullyClosure::do_yield_work() { | |
6959 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
6960 "CMS thread should hold CMS token"); | |
6961 assert_lock_strong(_freelistLock); | |
6962 assert_lock_strong(_bitMap->lock()); | |
6963 // relinquish the free_list_lock and bitMaplock() | |
6964 _bitMap->lock()->unlock(); | |
6965 _freelistLock->unlock(); | |
6966 ConcurrentMarkSweepThread::desynchronize(true); | |
6967 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
6968 _collector->stopTimer(); | |
6969 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
6970 if (PrintCMSStatistics != 0) { | |
6971 _collector->incrementYields(); | |
6972 } | |
6973 _collector->icms_wait(); | |
6974 | |
6975 // See the comment in coordinator_yield() | |
6976 for (unsigned i = 0; i < CMSYieldSleepCount && | |
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6977 ConcurrentMarkSweepThread::should_yield() && |
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6978 !CMSCollector::foregroundGCIsActive(); ++i) { |
0 | 6979 os::sleep(Thread::current(), 1, false); |
6980 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
6981 } | |
6982 | |
6983 ConcurrentMarkSweepThread::synchronize(true); | |
6984 _freelistLock->lock_without_safepoint_check(); | |
6985 _bitMap->lock()->lock_without_safepoint_check(); | |
6986 _collector->startTimer(); | |
6987 } | |
6988 | |
6989 | |
6990 ////////////////////////////////////////////////////////////////// | |
6991 // SurvivorSpacePrecleanClosure | |
6992 ////////////////////////////////////////////////////////////////// | |
6993 // This (single-threaded) closure is used to preclean the oops in | |
6994 // the survivor spaces. | |
6995 size_t SurvivorSpacePrecleanClosure::do_object_careful(oop p) { | |
6996 | |
6997 HeapWord* addr = (HeapWord*)p; | |
6998 DEBUG_ONLY(_collector->verify_work_stacks_empty();) | |
6999 assert(!_span.contains(addr), "we are scanning the survivor spaces"); | |
187 | 7000 assert(p->klass_or_null() != NULL, "object should be initializd"); |
0 | 7001 // an initialized object; ignore mark word in verification below |
7002 // since we are running concurrent with mutators | |
7003 assert(p->is_oop(true), "should be an oop"); | |
7004 // Note that we do not yield while we iterate over | |
7005 // the interior oops of p, pushing the relevant ones | |
7006 // on our marking stack. | |
7007 size_t size = p->oop_iterate(_scanning_closure); | |
7008 do_yield_check(); | |
7009 // Observe that below, we do not abandon the preclean | |
7010 // phase as soon as we should; rather we empty the | |
7011 // marking stack before returning. This is to satisfy | |
7012 // some existing assertions. In general, it may be a | |
7013 // good idea to abort immediately and complete the marking | |
7014 // from the grey objects at a later time. | |
7015 while (!_mark_stack->isEmpty()) { | |
7016 oop new_oop = _mark_stack->pop(); | |
7017 assert(new_oop != NULL && new_oop->is_oop(), "Expected an oop"); | |
7018 assert(_bit_map->isMarked((HeapWord*)new_oop), | |
7019 "only grey objects on this stack"); | |
7020 // iterate over the oops in this oop, marking and pushing | |
7021 // the ones in CMS heap (i.e. in _span). | |
7022 new_oop->oop_iterate(_scanning_closure); | |
7023 // check if it's time to yield | |
7024 do_yield_check(); | |
7025 } | |
7026 unsigned int after_count = | |
7027 GenCollectedHeap::heap()->total_collections(); | |
7028 bool abort = (_before_count != after_count) || | |
7029 _collector->should_abort_preclean(); | |
7030 return abort ? 0 : size; | |
7031 } | |
7032 | |
7033 void SurvivorSpacePrecleanClosure::do_yield_work() { | |
7034 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
7035 "CMS thread should hold CMS token"); | |
7036 assert_lock_strong(_bit_map->lock()); | |
7037 // Relinquish the bit map lock | |
7038 _bit_map->lock()->unlock(); | |
7039 ConcurrentMarkSweepThread::desynchronize(true); | |
7040 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
7041 _collector->stopTimer(); | |
7042 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
7043 if (PrintCMSStatistics != 0) { | |
7044 _collector->incrementYields(); | |
7045 } | |
7046 _collector->icms_wait(); | |
7047 | |
7048 // See the comment in coordinator_yield() | |
7049 for (unsigned i = 0; i < CMSYieldSleepCount && | |
7050 ConcurrentMarkSweepThread::should_yield() && | |
7051 !CMSCollector::foregroundGCIsActive(); ++i) { | |
7052 os::sleep(Thread::current(), 1, false); | |
7053 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
7054 } | |
7055 | |
7056 ConcurrentMarkSweepThread::synchronize(true); | |
7057 _bit_map->lock()->lock_without_safepoint_check(); | |
7058 _collector->startTimer(); | |
7059 } | |
7060 | |
7061 // This closure is used to rescan the marked objects on the dirty cards | |
7062 // in the mod union table and the card table proper. In the parallel | |
7063 // case, although the bitMap is shared, we do a single read so the | |
7064 // isMarked() query is "safe". | |
7065 bool ScanMarkedObjectsAgainClosure::do_object_bm(oop p, MemRegion mr) { | |
7066 // Ignore mark word because we are running concurrent with mutators | |
7067 assert(p->is_oop_or_null(true), "expected an oop or null"); | |
7068 HeapWord* addr = (HeapWord*)p; | |
7069 assert(_span.contains(addr), "we are scanning the CMS generation"); | |
7070 bool is_obj_array = false; | |
9152 | 7071 #ifdef ASSERT |
0 | 7072 if (!_parallel) { |
7073 assert(_mark_stack->isEmpty(), "pre-condition (eager drainage)"); | |
7074 assert(_collector->overflow_list_is_empty(), | |
7075 "overflow list should be empty"); | |
7076 | |
7077 } | |
9152 | 7078 #endif // ASSERT |
0 | 7079 if (_bit_map->isMarked(addr)) { |
7080 // Obj arrays are precisely marked, non-arrays are not; | |
7081 // so we scan objArrays precisely and non-arrays in their | |
7082 // entirety. | |
7083 if (p->is_objArray()) { | |
7084 is_obj_array = true; | |
7085 if (_parallel) { | |
7086 p->oop_iterate(_par_scan_closure, mr); | |
7087 } else { | |
7088 p->oop_iterate(_scan_closure, mr); | |
7089 } | |
7090 } else { | |
7091 if (_parallel) { | |
7092 p->oop_iterate(_par_scan_closure); | |
7093 } else { | |
7094 p->oop_iterate(_scan_closure); | |
7095 } | |
7096 } | |
7097 } | |
9152 | 7098 #ifdef ASSERT |
0 | 7099 if (!_parallel) { |
7100 assert(_mark_stack->isEmpty(), "post-condition (eager drainage)"); | |
7101 assert(_collector->overflow_list_is_empty(), | |
7102 "overflow list should be empty"); | |
7103 | |
7104 } | |
9152 | 7105 #endif // ASSERT |
0 | 7106 return is_obj_array; |
7107 } | |
7108 | |
7109 MarkFromRootsClosure::MarkFromRootsClosure(CMSCollector* collector, | |
7110 MemRegion span, | |
7111 CMSBitMap* bitMap, CMSMarkStack* markStack, | |
7112 bool should_yield, bool verifying): | |
7113 _collector(collector), | |
7114 _span(span), | |
7115 _bitMap(bitMap), | |
7116 _mut(&collector->_modUnionTable), | |
7117 _markStack(markStack), | |
7118 _yield(should_yield), | |
7119 _skipBits(0) | |
7120 { | |
7121 assert(_markStack->isEmpty(), "stack should be empty"); | |
7122 _finger = _bitMap->startWord(); | |
7123 _threshold = _finger; | |
7124 assert(_collector->_restart_addr == NULL, "Sanity check"); | |
7125 assert(_span.contains(_finger), "Out of bounds _finger?"); | |
7126 DEBUG_ONLY(_verifying = verifying;) | |
7127 } | |
7128 | |
7129 void MarkFromRootsClosure::reset(HeapWord* addr) { | |
7130 assert(_markStack->isEmpty(), "would cause duplicates on stack"); | |
7131 assert(_span.contains(addr), "Out of bounds _finger?"); | |
7132 _finger = addr; | |
7133 _threshold = (HeapWord*)round_to( | |
7134 (intptr_t)_finger, CardTableModRefBS::card_size); | |
7135 } | |
7136 | |
7137 // Should revisit to see if this should be restructured for | |
7138 // greater efficiency. | |
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7139 bool MarkFromRootsClosure::do_bit(size_t offset) { |
0 | 7140 if (_skipBits > 0) { |
7141 _skipBits--; | |
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7142 return true; |
0 | 7143 } |
7144 // convert offset into a HeapWord* | |
7145 HeapWord* addr = _bitMap->startWord() + offset; | |
7146 assert(_bitMap->endWord() && addr < _bitMap->endWord(), | |
7147 "address out of range"); | |
7148 assert(_bitMap->isMarked(addr), "tautology"); | |
7149 if (_bitMap->isMarked(addr+1)) { | |
7150 // this is an allocated but not yet initialized object | |
7151 assert(_skipBits == 0, "tautology"); | |
7152 _skipBits = 2; // skip next two marked bits ("Printezis-marks") | |
7153 oop p = oop(addr); | |
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7154 if (p->klass_or_null() == NULL) { |
0 | 7155 DEBUG_ONLY(if (!_verifying) {) |
7156 // We re-dirty the cards on which this object lies and increase | |
7157 // the _threshold so that we'll come back to scan this object | |
7158 // during the preclean or remark phase. (CMSCleanOnEnter) | |
7159 if (CMSCleanOnEnter) { | |
7160 size_t sz = _collector->block_size_using_printezis_bits(addr); | |
7161 HeapWord* end_card_addr = (HeapWord*)round_to( | |
7162 (intptr_t)(addr+sz), CardTableModRefBS::card_size); | |
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7163 MemRegion redirty_range = MemRegion(addr, end_card_addr); |
0 | 7164 assert(!redirty_range.is_empty(), "Arithmetical tautology"); |
7165 // Bump _threshold to end_card_addr; note that | |
7166 // _threshold cannot possibly exceed end_card_addr, anyhow. | |
7167 // This prevents future clearing of the card as the scan proceeds | |
7168 // to the right. | |
7169 assert(_threshold <= end_card_addr, | |
7170 "Because we are just scanning into this object"); | |
7171 if (_threshold < end_card_addr) { | |
7172 _threshold = end_card_addr; | |
7173 } | |
187 | 7174 if (p->klass_or_null() != NULL) { |
0 | 7175 // Redirty the range of cards... |
7176 _mut->mark_range(redirty_range); | |
7177 } // ...else the setting of klass will dirty the card anyway. | |
7178 } | |
7179 DEBUG_ONLY(}) | |
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7180 return true; |
0 | 7181 } |
7182 } | |
7183 scanOopsInOop(addr); | |
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7184 return true; |
0 | 7185 } |
7186 | |
7187 // We take a break if we've been at this for a while, | |
7188 // so as to avoid monopolizing the locks involved. | |
7189 void MarkFromRootsClosure::do_yield_work() { | |
7190 // First give up the locks, then yield, then re-lock | |
7191 // We should probably use a constructor/destructor idiom to | |
7192 // do this unlock/lock or modify the MutexUnlocker class to | |
7193 // serve our purpose. XXX | |
7194 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
7195 "CMS thread should hold CMS token"); | |
7196 assert_lock_strong(_bitMap->lock()); | |
7197 _bitMap->lock()->unlock(); | |
7198 ConcurrentMarkSweepThread::desynchronize(true); | |
7199 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
7200 _collector->stopTimer(); | |
7201 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
7202 if (PrintCMSStatistics != 0) { | |
7203 _collector->incrementYields(); | |
7204 } | |
7205 _collector->icms_wait(); | |
7206 | |
7207 // See the comment in coordinator_yield() | |
7208 for (unsigned i = 0; i < CMSYieldSleepCount && | |
7209 ConcurrentMarkSweepThread::should_yield() && | |
7210 !CMSCollector::foregroundGCIsActive(); ++i) { | |
7211 os::sleep(Thread::current(), 1, false); | |
7212 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
7213 } | |
7214 | |
7215 ConcurrentMarkSweepThread::synchronize(true); | |
7216 _bitMap->lock()->lock_without_safepoint_check(); | |
7217 _collector->startTimer(); | |
7218 } | |
7219 | |
7220 void MarkFromRootsClosure::scanOopsInOop(HeapWord* ptr) { | |
7221 assert(_bitMap->isMarked(ptr), "expected bit to be set"); | |
7222 assert(_markStack->isEmpty(), | |
7223 "should drain stack to limit stack usage"); | |
7224 // convert ptr to an oop preparatory to scanning | |
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7225 oop obj = oop(ptr); |
0 | 7226 // Ignore mark word in verification below, since we |
7227 // may be running concurrent with mutators. | |
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7228 assert(obj->is_oop(true), "should be an oop"); |
0 | 7229 assert(_finger <= ptr, "_finger runneth ahead"); |
7230 // advance the finger to right end of this object | |
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7231 _finger = ptr + obj->size(); |
0 | 7232 assert(_finger > ptr, "we just incremented it above"); |
7233 // On large heaps, it may take us some time to get through | |
7234 // the marking phase (especially if running iCMS). During | |
7235 // this time it's possible that a lot of mutations have | |
7236 // accumulated in the card table and the mod union table -- | |
7237 // these mutation records are redundant until we have | |
7238 // actually traced into the corresponding card. | |
7239 // Here, we check whether advancing the finger would make | |
7240 // us cross into a new card, and if so clear corresponding | |
7241 // cards in the MUT (preclean them in the card-table in the | |
7242 // future). | |
7243 | |
7244 DEBUG_ONLY(if (!_verifying) {) | |
7245 // The clean-on-enter optimization is disabled by default, | |
7246 // until we fix 6178663. | |
7247 if (CMSCleanOnEnter && (_finger > _threshold)) { | |
7248 // [_threshold, _finger) represents the interval | |
7249 // of cards to be cleared in MUT (or precleaned in card table). | |
7250 // The set of cards to be cleared is all those that overlap | |
7251 // with the interval [_threshold, _finger); note that | |
7252 // _threshold is always kept card-aligned but _finger isn't | |
7253 // always card-aligned. | |
7254 HeapWord* old_threshold = _threshold; | |
7255 assert(old_threshold == (HeapWord*)round_to( | |
7256 (intptr_t)old_threshold, CardTableModRefBS::card_size), | |
7257 "_threshold should always be card-aligned"); | |
7258 _threshold = (HeapWord*)round_to( | |
7259 (intptr_t)_finger, CardTableModRefBS::card_size); | |
7260 MemRegion mr(old_threshold, _threshold); | |
7261 assert(!mr.is_empty(), "Control point invariant"); | |
7262 assert(_span.contains(mr), "Should clear within span"); | |
7263 _mut->clear_range(mr); | |
7264 } | |
7265 DEBUG_ONLY(}) | |
7266 // Note: the finger doesn't advance while we drain | |
7267 // the stack below. | |
7268 PushOrMarkClosure pushOrMarkClosure(_collector, | |
7269 _span, _bitMap, _markStack, | |
7270 _finger, this); | |
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7271 bool res = _markStack->push(obj); |
0 | 7272 assert(res, "Empty non-zero size stack should have space for single push"); |
7273 while (!_markStack->isEmpty()) { | |
7274 oop new_oop = _markStack->pop(); | |
7275 // Skip verifying header mark word below because we are | |
7276 // running concurrent with mutators. | |
7277 assert(new_oop->is_oop(true), "Oops! expected to pop an oop"); | |
7278 // now scan this oop's oops | |
7279 new_oop->oop_iterate(&pushOrMarkClosure); | |
7280 do_yield_check(); | |
7281 } | |
7282 assert(_markStack->isEmpty(), "tautology, emphasizing post-condition"); | |
7283 } | |
7284 | |
7285 Par_MarkFromRootsClosure::Par_MarkFromRootsClosure(CMSConcMarkingTask* task, | |
7286 CMSCollector* collector, MemRegion span, | |
7287 CMSBitMap* bit_map, | |
7288 OopTaskQueue* work_queue, | |
7289 CMSMarkStack* overflow_stack, | |
7290 bool should_yield): | |
7291 _collector(collector), | |
7292 _whole_span(collector->_span), | |
7293 _span(span), | |
7294 _bit_map(bit_map), | |
7295 _mut(&collector->_modUnionTable), | |
7296 _work_queue(work_queue), | |
7297 _overflow_stack(overflow_stack), | |
7298 _yield(should_yield), | |
7299 _skip_bits(0), | |
7300 _task(task) | |
7301 { | |
7302 assert(_work_queue->size() == 0, "work_queue should be empty"); | |
7303 _finger = span.start(); | |
7304 _threshold = _finger; // XXX Defer clear-on-enter optimization for now | |
7305 assert(_span.contains(_finger), "Out of bounds _finger?"); | |
7306 } | |
7307 | |
7308 // Should revisit to see if this should be restructured for | |
7309 // greater efficiency. | |
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7310 bool Par_MarkFromRootsClosure::do_bit(size_t offset) { |
0 | 7311 if (_skip_bits > 0) { |
7312 _skip_bits--; | |
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7313 return true; |
0 | 7314 } |
7315 // convert offset into a HeapWord* | |
7316 HeapWord* addr = _bit_map->startWord() + offset; | |
7317 assert(_bit_map->endWord() && addr < _bit_map->endWord(), | |
7318 "address out of range"); | |
7319 assert(_bit_map->isMarked(addr), "tautology"); | |
7320 if (_bit_map->isMarked(addr+1)) { | |
7321 // this is an allocated object that might not yet be initialized | |
7322 assert(_skip_bits == 0, "tautology"); | |
7323 _skip_bits = 2; // skip next two marked bits ("Printezis-marks") | |
7324 oop p = oop(addr); | |
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7325 if (p->klass_or_null() == NULL) { |
0 | 7326 // in the case of Clean-on-Enter optimization, redirty card |
7327 // and avoid clearing card by increasing the threshold. | |
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7328 return true; |
0 | 7329 } |
7330 } | |
7331 scan_oops_in_oop(addr); | |
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7332 return true; |
0 | 7333 } |
7334 | |
7335 void Par_MarkFromRootsClosure::scan_oops_in_oop(HeapWord* ptr) { | |
7336 assert(_bit_map->isMarked(ptr), "expected bit to be set"); | |
7337 // Should we assert that our work queue is empty or | |
7338 // below some drain limit? | |
7339 assert(_work_queue->size() == 0, | |
7340 "should drain stack to limit stack usage"); | |
7341 // convert ptr to an oop preparatory to scanning | |
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7342 oop obj = oop(ptr); |
0 | 7343 // Ignore mark word in verification below, since we |
7344 // may be running concurrent with mutators. | |
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7345 assert(obj->is_oop(true), "should be an oop"); |
0 | 7346 assert(_finger <= ptr, "_finger runneth ahead"); |
7347 // advance the finger to right end of this object | |
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7348 _finger = ptr + obj->size(); |
0 | 7349 assert(_finger > ptr, "we just incremented it above"); |
7350 // On large heaps, it may take us some time to get through | |
7351 // the marking phase (especially if running iCMS). During | |
7352 // this time it's possible that a lot of mutations have | |
7353 // accumulated in the card table and the mod union table -- | |
7354 // these mutation records are redundant until we have | |
7355 // actually traced into the corresponding card. | |
7356 // Here, we check whether advancing the finger would make | |
7357 // us cross into a new card, and if so clear corresponding | |
7358 // cards in the MUT (preclean them in the card-table in the | |
7359 // future). | |
7360 | |
7361 // The clean-on-enter optimization is disabled by default, | |
7362 // until we fix 6178663. | |
7363 if (CMSCleanOnEnter && (_finger > _threshold)) { | |
7364 // [_threshold, _finger) represents the interval | |
7365 // of cards to be cleared in MUT (or precleaned in card table). | |
7366 // The set of cards to be cleared is all those that overlap | |
7367 // with the interval [_threshold, _finger); note that | |
7368 // _threshold is always kept card-aligned but _finger isn't | |
7369 // always card-aligned. | |
7370 HeapWord* old_threshold = _threshold; | |
7371 assert(old_threshold == (HeapWord*)round_to( | |
7372 (intptr_t)old_threshold, CardTableModRefBS::card_size), | |
7373 "_threshold should always be card-aligned"); | |
7374 _threshold = (HeapWord*)round_to( | |
7375 (intptr_t)_finger, CardTableModRefBS::card_size); | |
7376 MemRegion mr(old_threshold, _threshold); | |
7377 assert(!mr.is_empty(), "Control point invariant"); | |
7378 assert(_span.contains(mr), "Should clear within span"); // _whole_span ?? | |
7379 _mut->clear_range(mr); | |
7380 } | |
7381 | |
7382 // Note: the local finger doesn't advance while we drain | |
7383 // the stack below, but the global finger sure can and will. | |
7384 HeapWord** gfa = _task->global_finger_addr(); | |
7385 Par_PushOrMarkClosure pushOrMarkClosure(_collector, | |
7386 _span, _bit_map, | |
7387 _work_queue, | |
7388 _overflow_stack, | |
7389 _finger, | |
7390 gfa, this); | |
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7391 bool res = _work_queue->push(obj); // overflow could occur here |
0 | 7392 assert(res, "Will hold once we use workqueues"); |
7393 while (true) { | |
7394 oop new_oop; | |
7395 if (!_work_queue->pop_local(new_oop)) { | |
7396 // We emptied our work_queue; check if there's stuff that can | |
7397 // be gotten from the overflow stack. | |
7398 if (CMSConcMarkingTask::get_work_from_overflow_stack( | |
7399 _overflow_stack, _work_queue)) { | |
7400 do_yield_check(); | |
7401 continue; | |
7402 } else { // done | |
7403 break; | |
7404 } | |
7405 } | |
7406 // Skip verifying header mark word below because we are | |
7407 // running concurrent with mutators. | |
7408 assert(new_oop->is_oop(true), "Oops! expected to pop an oop"); | |
7409 // now scan this oop's oops | |
7410 new_oop->oop_iterate(&pushOrMarkClosure); | |
7411 do_yield_check(); | |
7412 } | |
7413 assert(_work_queue->size() == 0, "tautology, emphasizing post-condition"); | |
7414 } | |
7415 | |
7416 // Yield in response to a request from VM Thread or | |
7417 // from mutators. | |
7418 void Par_MarkFromRootsClosure::do_yield_work() { | |
7419 assert(_task != NULL, "sanity"); | |
7420 _task->yield(); | |
7421 } | |
7422 | |
7423 // A variant of the above used for verifying CMS marking work. | |
7424 MarkFromRootsVerifyClosure::MarkFromRootsVerifyClosure(CMSCollector* collector, | |
7425 MemRegion span, | |
7426 CMSBitMap* verification_bm, CMSBitMap* cms_bm, | |
7427 CMSMarkStack* mark_stack): | |
7428 _collector(collector), | |
7429 _span(span), | |
7430 _verification_bm(verification_bm), | |
7431 _cms_bm(cms_bm), | |
7432 _mark_stack(mark_stack), | |
7433 _pam_verify_closure(collector, span, verification_bm, cms_bm, | |
7434 mark_stack) | |
7435 { | |
7436 assert(_mark_stack->isEmpty(), "stack should be empty"); | |
7437 _finger = _verification_bm->startWord(); | |
7438 assert(_collector->_restart_addr == NULL, "Sanity check"); | |
7439 assert(_span.contains(_finger), "Out of bounds _finger?"); | |
7440 } | |
7441 | |
7442 void MarkFromRootsVerifyClosure::reset(HeapWord* addr) { | |
7443 assert(_mark_stack->isEmpty(), "would cause duplicates on stack"); | |
7444 assert(_span.contains(addr), "Out of bounds _finger?"); | |
7445 _finger = addr; | |
7446 } | |
7447 | |
7448 // Should revisit to see if this should be restructured for | |
7449 // greater efficiency. | |
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7450 bool MarkFromRootsVerifyClosure::do_bit(size_t offset) { |
0 | 7451 // convert offset into a HeapWord* |
7452 HeapWord* addr = _verification_bm->startWord() + offset; | |
7453 assert(_verification_bm->endWord() && addr < _verification_bm->endWord(), | |
7454 "address out of range"); | |
7455 assert(_verification_bm->isMarked(addr), "tautology"); | |
7456 assert(_cms_bm->isMarked(addr), "tautology"); | |
7457 | |
7458 assert(_mark_stack->isEmpty(), | |
7459 "should drain stack to limit stack usage"); | |
7460 // convert addr to an oop preparatory to scanning | |
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7461 oop obj = oop(addr); |
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7462 assert(obj->is_oop(), "should be an oop"); |
0 | 7463 assert(_finger <= addr, "_finger runneth ahead"); |
7464 // advance the finger to right end of this object | |
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7465 _finger = addr + obj->size(); |
0 | 7466 assert(_finger > addr, "we just incremented it above"); |
7467 // Note: the finger doesn't advance while we drain | |
7468 // the stack below. | |
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7469 bool res = _mark_stack->push(obj); |
0 | 7470 assert(res, "Empty non-zero size stack should have space for single push"); |
7471 while (!_mark_stack->isEmpty()) { | |
7472 oop new_oop = _mark_stack->pop(); | |
7473 assert(new_oop->is_oop(), "Oops! expected to pop an oop"); | |
7474 // now scan this oop's oops | |
7475 new_oop->oop_iterate(&_pam_verify_closure); | |
7476 } | |
7477 assert(_mark_stack->isEmpty(), "tautology, emphasizing post-condition"); | |
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7478 return true; |
0 | 7479 } |
7480 | |
7481 PushAndMarkVerifyClosure::PushAndMarkVerifyClosure( | |
7482 CMSCollector* collector, MemRegion span, | |
7483 CMSBitMap* verification_bm, CMSBitMap* cms_bm, | |
7484 CMSMarkStack* mark_stack): | |
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7485 CMSOopClosure(collector->ref_processor()), |
0 | 7486 _collector(collector), |
7487 _span(span), | |
7488 _verification_bm(verification_bm), | |
7489 _cms_bm(cms_bm), | |
7490 _mark_stack(mark_stack) | |
7491 { } | |
7492 | |
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7493 void PushAndMarkVerifyClosure::do_oop(oop* p) { PushAndMarkVerifyClosure::do_oop_work(p); } |
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7494 void PushAndMarkVerifyClosure::do_oop(narrowOop* p) { PushAndMarkVerifyClosure::do_oop_work(p); } |
0 | 7495 |
7496 // Upon stack overflow, we discard (part of) the stack, | |
7497 // remembering the least address amongst those discarded | |
7498 // in CMSCollector's _restart_address. | |
7499 void PushAndMarkVerifyClosure::handle_stack_overflow(HeapWord* lost) { | |
7500 // Remember the least grey address discarded | |
7501 HeapWord* ra = (HeapWord*)_mark_stack->least_value(lost); | |
7502 _collector->lower_restart_addr(ra); | |
7503 _mark_stack->reset(); // discard stack contents | |
7504 _mark_stack->expand(); // expand the stack if possible | |
7505 } | |
7506 | |
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7507 void PushAndMarkVerifyClosure::do_oop(oop obj) { |
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7508 assert(obj->is_oop_or_null(), "expected an oop or NULL"); |
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7509 HeapWord* addr = (HeapWord*)obj; |
0 | 7510 if (_span.contains(addr) && !_verification_bm->isMarked(addr)) { |
7511 // Oop lies in _span and isn't yet grey or black | |
7512 _verification_bm->mark(addr); // now grey | |
7513 if (!_cms_bm->isMarked(addr)) { | |
7514 oop(addr)->print(); | |
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7515 gclog_or_tty->print_cr(" (" INTPTR_FORMAT " should have been marked)", |
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7516 addr); |
0 | 7517 fatal("... aborting"); |
7518 } | |
7519 | |
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7520 if (!_mark_stack->push(obj)) { // stack overflow |
0 | 7521 if (PrintCMSStatistics != 0) { |
7522 gclog_or_tty->print_cr("CMS marking stack overflow (benign) at " | |
7523 SIZE_FORMAT, _mark_stack->capacity()); | |
7524 } | |
7525 assert(_mark_stack->isFull(), "Else push should have succeeded"); | |
7526 handle_stack_overflow(addr); | |
7527 } | |
7528 // anything including and to the right of _finger | |
7529 // will be scanned as we iterate over the remainder of the | |
7530 // bit map | |
7531 } | |
7532 } | |
7533 | |
7534 PushOrMarkClosure::PushOrMarkClosure(CMSCollector* collector, | |
7535 MemRegion span, | |
7536 CMSBitMap* bitMap, CMSMarkStack* markStack, | |
7537 HeapWord* finger, MarkFromRootsClosure* parent) : | |
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7538 CMSOopClosure(collector->ref_processor()), |
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7539 _collector(collector), |
0 | 7540 _span(span), |
7541 _bitMap(bitMap), | |
7542 _markStack(markStack), | |
7543 _finger(finger), | |
935 | 7544 _parent(parent) |
0 | 7545 { } |
7546 | |
7547 Par_PushOrMarkClosure::Par_PushOrMarkClosure(CMSCollector* collector, | |
7548 MemRegion span, | |
7549 CMSBitMap* bit_map, | |
7550 OopTaskQueue* work_queue, | |
7551 CMSMarkStack* overflow_stack, | |
7552 HeapWord* finger, | |
7553 HeapWord** global_finger_addr, | |
7554 Par_MarkFromRootsClosure* parent) : | |
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7555 CMSOopClosure(collector->ref_processor()), |
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7556 _collector(collector), |
0 | 7557 _whole_span(collector->_span), |
7558 _span(span), | |
7559 _bit_map(bit_map), | |
7560 _work_queue(work_queue), | |
7561 _overflow_stack(overflow_stack), | |
7562 _finger(finger), | |
7563 _global_finger_addr(global_finger_addr), | |
935 | 7564 _parent(parent) |
0 | 7565 { } |
7566 | |
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7567 // Assumes thread-safe access by callers, who are |
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7568 // responsible for mutual exclusion. |
0 | 7569 void CMSCollector::lower_restart_addr(HeapWord* low) { |
7570 assert(_span.contains(low), "Out of bounds addr"); | |
7571 if (_restart_addr == NULL) { | |
7572 _restart_addr = low; | |
7573 } else { | |
7574 _restart_addr = MIN2(_restart_addr, low); | |
7575 } | |
7576 } | |
7577 | |
7578 // Upon stack overflow, we discard (part of) the stack, | |
7579 // remembering the least address amongst those discarded | |
7580 // in CMSCollector's _restart_address. | |
7581 void PushOrMarkClosure::handle_stack_overflow(HeapWord* lost) { | |
7582 // Remember the least grey address discarded | |
7583 HeapWord* ra = (HeapWord*)_markStack->least_value(lost); | |
7584 _collector->lower_restart_addr(ra); | |
7585 _markStack->reset(); // discard stack contents | |
7586 _markStack->expand(); // expand the stack if possible | |
7587 } | |
7588 | |
7589 // Upon stack overflow, we discard (part of) the stack, | |
7590 // remembering the least address amongst those discarded | |
7591 // in CMSCollector's _restart_address. | |
7592 void Par_PushOrMarkClosure::handle_stack_overflow(HeapWord* lost) { | |
7593 // We need to do this under a mutex to prevent other | |
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7594 // workers from interfering with the work done below. |
0 | 7595 MutexLockerEx ml(_overflow_stack->par_lock(), |
7596 Mutex::_no_safepoint_check_flag); | |
7597 // Remember the least grey address discarded | |
7598 HeapWord* ra = (HeapWord*)_overflow_stack->least_value(lost); | |
7599 _collector->lower_restart_addr(ra); | |
7600 _overflow_stack->reset(); // discard stack contents | |
7601 _overflow_stack->expand(); // expand the stack if possible | |
7602 } | |
7603 | |
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7604 void CMKlassClosure::do_klass(Klass* k) { |
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7605 assert(_oop_closure != NULL, "Not initialized?"); |
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7606 k->oops_do(_oop_closure); |
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7607 } |
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7608 |
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7609 void PushOrMarkClosure::do_oop(oop obj) { |
0 | 7610 // Ignore mark word because we are running concurrent with mutators. |
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7611 assert(obj->is_oop_or_null(true), "expected an oop or NULL"); |
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7612 HeapWord* addr = (HeapWord*)obj; |
0 | 7613 if (_span.contains(addr) && !_bitMap->isMarked(addr)) { |
7614 // Oop lies in _span and isn't yet grey or black | |
7615 _bitMap->mark(addr); // now grey | |
7616 if (addr < _finger) { | |
7617 // the bit map iteration has already either passed, or | |
7618 // sampled, this bit in the bit map; we'll need to | |
7619 // use the marking stack to scan this oop's oops. | |
7620 bool simulate_overflow = false; | |
7621 NOT_PRODUCT( | |
7622 if (CMSMarkStackOverflowALot && | |
7623 _collector->simulate_overflow()) { | |
7624 // simulate a stack overflow | |
7625 simulate_overflow = true; | |
7626 } | |
7627 ) | |
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7628 if (simulate_overflow || !_markStack->push(obj)) { // stack overflow |
0 | 7629 if (PrintCMSStatistics != 0) { |
7630 gclog_or_tty->print_cr("CMS marking stack overflow (benign) at " | |
7631 SIZE_FORMAT, _markStack->capacity()); | |
7632 } | |
7633 assert(simulate_overflow || _markStack->isFull(), "Else push should have succeeded"); | |
7634 handle_stack_overflow(addr); | |
7635 } | |
7636 } | |
7637 // anything including and to the right of _finger | |
7638 // will be scanned as we iterate over the remainder of the | |
7639 // bit map | |
7640 do_yield_check(); | |
7641 } | |
7642 } | |
7643 | |
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7644 void PushOrMarkClosure::do_oop(oop* p) { PushOrMarkClosure::do_oop_work(p); } |
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7645 void PushOrMarkClosure::do_oop(narrowOop* p) { PushOrMarkClosure::do_oop_work(p); } |
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7646 |
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7647 void Par_PushOrMarkClosure::do_oop(oop obj) { |
0 | 7648 // Ignore mark word because we are running concurrent with mutators. |
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7649 assert(obj->is_oop_or_null(true), "expected an oop or NULL"); |
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7650 HeapWord* addr = (HeapWord*)obj; |
0 | 7651 if (_whole_span.contains(addr) && !_bit_map->isMarked(addr)) { |
7652 // Oop lies in _span and isn't yet grey or black | |
7653 // We read the global_finger (volatile read) strictly after marking oop | |
7654 bool res = _bit_map->par_mark(addr); // now grey | |
7655 volatile HeapWord** gfa = (volatile HeapWord**)_global_finger_addr; | |
7656 // Should we push this marked oop on our stack? | |
7657 // -- if someone else marked it, nothing to do | |
7658 // -- if target oop is above global finger nothing to do | |
7659 // -- if target oop is in chunk and above local finger | |
7660 // then nothing to do | |
7661 // -- else push on work queue | |
7662 if ( !res // someone else marked it, they will deal with it | |
7663 || (addr >= *gfa) // will be scanned in a later task | |
7664 || (_span.contains(addr) && addr >= _finger)) { // later in this chunk | |
7665 return; | |
7666 } | |
7667 // the bit map iteration has already either passed, or | |
7668 // sampled, this bit in the bit map; we'll need to | |
7669 // use the marking stack to scan this oop's oops. | |
7670 bool simulate_overflow = false; | |
7671 NOT_PRODUCT( | |
7672 if (CMSMarkStackOverflowALot && | |
7673 _collector->simulate_overflow()) { | |
7674 // simulate a stack overflow | |
7675 simulate_overflow = true; | |
7676 } | |
7677 ) | |
7678 if (simulate_overflow || | |
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7679 !(_work_queue->push(obj) || _overflow_stack->par_push(obj))) { |
0 | 7680 // stack overflow |
7681 if (PrintCMSStatistics != 0) { | |
7682 gclog_or_tty->print_cr("CMS marking stack overflow (benign) at " | |
7683 SIZE_FORMAT, _overflow_stack->capacity()); | |
7684 } | |
7685 // We cannot assert that the overflow stack is full because | |
7686 // it may have been emptied since. | |
7687 assert(simulate_overflow || | |
7688 _work_queue->size() == _work_queue->max_elems(), | |
7689 "Else push should have succeeded"); | |
7690 handle_stack_overflow(addr); | |
7691 } | |
7692 do_yield_check(); | |
7693 } | |
7694 } | |
7695 | |
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7696 void Par_PushOrMarkClosure::do_oop(oop* p) { Par_PushOrMarkClosure::do_oop_work(p); } |
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7697 void Par_PushOrMarkClosure::do_oop(narrowOop* p) { Par_PushOrMarkClosure::do_oop_work(p); } |
0 | 7698 |
7699 PushAndMarkClosure::PushAndMarkClosure(CMSCollector* collector, | |
7700 MemRegion span, | |
7701 ReferenceProcessor* rp, | |
7702 CMSBitMap* bit_map, | |
7703 CMSBitMap* mod_union_table, | |
7704 CMSMarkStack* mark_stack, | |
7705 bool concurrent_precleaning): | |
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7706 CMSOopClosure(rp), |
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7707 _collector(collector), |
0 | 7708 _span(span), |
7709 _bit_map(bit_map), | |
7710 _mod_union_table(mod_union_table), | |
7711 _mark_stack(mark_stack), | |
935 | 7712 _concurrent_precleaning(concurrent_precleaning) |
0 | 7713 { |
7714 assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL"); | |
7715 } | |
7716 | |
7717 // Grey object rescan during pre-cleaning and second checkpoint phases -- | |
7718 // the non-parallel version (the parallel version appears further below.) | |
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7719 void PushAndMarkClosure::do_oop(oop obj) { |
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7720 // Ignore mark word verification. If during concurrent precleaning, |
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7721 // the object monitor may be locked. If during the checkpoint |
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7722 // phases, the object may already have been reached by a different |
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7723 // path and may be at the end of the global overflow list (so |
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7724 // the mark word may be NULL). |
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7725 assert(obj->is_oop_or_null(true /* ignore mark word */), |
0 | 7726 "expected an oop or NULL"); |
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7727 HeapWord* addr = (HeapWord*)obj; |
0 | 7728 // Check if oop points into the CMS generation |
7729 // and is not marked | |
7730 if (_span.contains(addr) && !_bit_map->isMarked(addr)) { | |
7731 // a white object ... | |
7732 _bit_map->mark(addr); // ... now grey | |
7733 // push on the marking stack (grey set) | |
7734 bool simulate_overflow = false; | |
7735 NOT_PRODUCT( | |
7736 if (CMSMarkStackOverflowALot && | |
7737 _collector->simulate_overflow()) { | |
7738 // simulate a stack overflow | |
7739 simulate_overflow = true; | |
7740 } | |
7741 ) | |
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7742 if (simulate_overflow || !_mark_stack->push(obj)) { |
0 | 7743 if (_concurrent_precleaning) { |
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7744 // During precleaning we can just dirty the appropriate card(s) |
0 | 7745 // in the mod union table, thus ensuring that the object remains |
283
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7746 // in the grey set and continue. In the case of object arrays |
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7747 // we need to dirty all of the cards that the object spans, |
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7748 // since the rescan of object arrays will be limited to the |
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7749 // dirty cards. |
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7750 // Note that no one can be intefering with us in this action |
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7751 // of dirtying the mod union table, so no locking or atomics |
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7752 // are required. |
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7753 if (obj->is_objArray()) { |
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7754 size_t sz = obj->size(); |
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7755 HeapWord* end_card_addr = (HeapWord*)round_to( |
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7756 (intptr_t)(addr+sz), CardTableModRefBS::card_size); |
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7757 MemRegion redirty_range = MemRegion(addr, end_card_addr); |
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7758 assert(!redirty_range.is_empty(), "Arithmetical tautology"); |
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7759 _mod_union_table->mark_range(redirty_range); |
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7760 } else { |
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7761 _mod_union_table->mark(addr); |
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7762 } |
0 | 7763 _collector->_ser_pmc_preclean_ovflw++; |
7764 } else { | |
7765 // During the remark phase, we need to remember this oop | |
7766 // in the overflow list. | |
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7767 _collector->push_on_overflow_list(obj); |
0 | 7768 _collector->_ser_pmc_remark_ovflw++; |
7769 } | |
7770 } | |
7771 } | |
7772 } | |
7773 | |
7774 Par_PushAndMarkClosure::Par_PushAndMarkClosure(CMSCollector* collector, | |
7775 MemRegion span, | |
7776 ReferenceProcessor* rp, | |
7777 CMSBitMap* bit_map, | |
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7778 OopTaskQueue* work_queue): |
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7779 CMSOopClosure(rp), |
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7780 _collector(collector), |
0 | 7781 _span(span), |
7782 _bit_map(bit_map), | |
935 | 7783 _work_queue(work_queue) |
0 | 7784 { |
7785 assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL"); | |
7786 } | |
7787 | |
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7788 void PushAndMarkClosure::do_oop(oop* p) { PushAndMarkClosure::do_oop_work(p); } |
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7789 void PushAndMarkClosure::do_oop(narrowOop* p) { PushAndMarkClosure::do_oop_work(p); } |
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7790 |
0 | 7791 // Grey object rescan during second checkpoint phase -- |
7792 // the parallel version. | |
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7793 void Par_PushAndMarkClosure::do_oop(oop obj) { |
0 | 7794 // In the assert below, we ignore the mark word because |
7795 // this oop may point to an already visited object that is | |
7796 // on the overflow stack (in which case the mark word has | |
7797 // been hijacked for chaining into the overflow stack -- | |
7798 // if this is the last object in the overflow stack then | |
7799 // its mark word will be NULL). Because this object may | |
7800 // have been subsequently popped off the global overflow | |
7801 // stack, and the mark word possibly restored to the prototypical | |
7802 // value, by the time we get to examined this failing assert in | |
7803 // the debugger, is_oop_or_null(false) may subsequently start | |
7804 // to hold. | |
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7805 assert(obj->is_oop_or_null(true), |
0 | 7806 "expected an oop or NULL"); |
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7807 HeapWord* addr = (HeapWord*)obj; |
0 | 7808 // Check if oop points into the CMS generation |
7809 // and is not marked | |
7810 if (_span.contains(addr) && !_bit_map->isMarked(addr)) { | |
7811 // a white object ... | |
7812 // If we manage to "claim" the object, by being the | |
7813 // first thread to mark it, then we push it on our | |
7814 // marking stack | |
7815 if (_bit_map->par_mark(addr)) { // ... now grey | |
7816 // push on work queue (grey set) | |
7817 bool simulate_overflow = false; | |
7818 NOT_PRODUCT( | |
7819 if (CMSMarkStackOverflowALot && | |
7820 _collector->par_simulate_overflow()) { | |
7821 // simulate a stack overflow | |
7822 simulate_overflow = true; | |
7823 } | |
7824 ) | |
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7825 if (simulate_overflow || !_work_queue->push(obj)) { |
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7826 _collector->par_push_on_overflow_list(obj); |
0 | 7827 _collector->_par_pmc_remark_ovflw++; // imprecise OK: no need to CAS |
7828 } | |
7829 } // Else, some other thread got there first | |
7830 } | |
7831 } | |
7832 | |
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7833 void Par_PushAndMarkClosure::do_oop(oop* p) { Par_PushAndMarkClosure::do_oop_work(p); } |
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7834 void Par_PushAndMarkClosure::do_oop(narrowOop* p) { Par_PushAndMarkClosure::do_oop_work(p); } |
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7835 |
0 | 7836 void CMSPrecleanRefsYieldClosure::do_yield_work() { |
7837 Mutex* bml = _collector->bitMapLock(); | |
7838 assert_lock_strong(bml); | |
7839 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
7840 "CMS thread should hold CMS token"); | |
7841 | |
7842 bml->unlock(); | |
7843 ConcurrentMarkSweepThread::desynchronize(true); | |
7844 | |
7845 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
7846 | |
7847 _collector->stopTimer(); | |
7848 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
7849 if (PrintCMSStatistics != 0) { | |
7850 _collector->incrementYields(); | |
7851 } | |
7852 _collector->icms_wait(); | |
7853 | |
7854 // See the comment in coordinator_yield() | |
7855 for (unsigned i = 0; i < CMSYieldSleepCount && | |
7856 ConcurrentMarkSweepThread::should_yield() && | |
7857 !CMSCollector::foregroundGCIsActive(); ++i) { | |
7858 os::sleep(Thread::current(), 1, false); | |
7859 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
7860 } | |
7861 | |
7862 ConcurrentMarkSweepThread::synchronize(true); | |
7863 bml->lock(); | |
7864 | |
7865 _collector->startTimer(); | |
7866 } | |
7867 | |
7868 bool CMSPrecleanRefsYieldClosure::should_return() { | |
7869 if (ConcurrentMarkSweepThread::should_yield()) { | |
7870 do_yield_work(); | |
7871 } | |
7872 return _collector->foregroundGCIsActive(); | |
7873 } | |
7874 | |
7875 void MarkFromDirtyCardsClosure::do_MemRegion(MemRegion mr) { | |
7876 assert(((size_t)mr.start())%CardTableModRefBS::card_size_in_words == 0, | |
7877 "mr should be aligned to start at a card boundary"); | |
7878 // We'd like to assert: | |
7879 // assert(mr.word_size()%CardTableModRefBS::card_size_in_words == 0, | |
7880 // "mr should be a range of cards"); | |
7881 // However, that would be too strong in one case -- the last | |
7882 // partition ends at _unallocated_block which, in general, can be | |
7883 // an arbitrary boundary, not necessarily card aligned. | |
7884 if (PrintCMSStatistics != 0) { | |
7885 _num_dirty_cards += | |
7886 mr.word_size()/CardTableModRefBS::card_size_in_words; | |
7887 } | |
7888 _space->object_iterate_mem(mr, &_scan_cl); | |
7889 } | |
7890 | |
7891 SweepClosure::SweepClosure(CMSCollector* collector, | |
7892 ConcurrentMarkSweepGeneration* g, | |
7893 CMSBitMap* bitMap, bool should_yield) : | |
7894 _collector(collector), | |
7895 _g(g), | |
7896 _sp(g->cmsSpace()), | |
7897 _limit(_sp->sweep_limit()), | |
7898 _freelistLock(_sp->freelistLock()), | |
7899 _bitMap(bitMap), | |
7900 _yield(should_yield), | |
7901 _inFreeRange(false), // No free range at beginning of sweep | |
7902 _freeRangeInFreeLists(false), // No free range at beginning of sweep | |
7903 _lastFreeRangeCoalesced(false), | |
7904 _freeFinger(g->used_region().start()) | |
7905 { | |
7906 NOT_PRODUCT( | |
7907 _numObjectsFreed = 0; | |
7908 _numWordsFreed = 0; | |
7909 _numObjectsLive = 0; | |
7910 _numWordsLive = 0; | |
7911 _numObjectsAlreadyFree = 0; | |
7912 _numWordsAlreadyFree = 0; | |
7913 _last_fc = NULL; | |
7914 | |
7915 _sp->initializeIndexedFreeListArrayReturnedBytes(); | |
6028
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7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
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6026
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|
7916 _sp->dictionary()->initialize_dict_returned_bytes(); |
0 | 7917 ) |
7918 assert(_limit >= _sp->bottom() && _limit <= _sp->end(), | |
7919 "sweep _limit out of bounds"); | |
7920 if (CMSTraceSweeper) { | |
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
7921 gclog_or_tty->print_cr("\n====================\nStarting new sweep with limit " PTR_FORMAT, |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
7922 _limit); |
537a4053b0f9
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|
7923 } |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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|
7924 } |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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|
7925 |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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|
7926 void SweepClosure::print_on(outputStream* st) const { |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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|
7927 tty->print_cr("_sp = [" PTR_FORMAT "," PTR_FORMAT ")", |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
7928 _sp->bottom(), _sp->end()); |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
7929 tty->print_cr("_limit = " PTR_FORMAT, _limit); |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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|
7930 tty->print_cr("_freeFinger = " PTR_FORMAT, _freeFinger); |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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|
7931 NOT_PRODUCT(tty->print_cr("_last_fc = " PTR_FORMAT, _last_fc);) |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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|
7932 tty->print_cr("_inFreeRange = %d, _freeRangeInFreeLists = %d, _lastFreeRangeCoalesced = %d", |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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|
7933 _inFreeRange, _freeRangeInFreeLists, _lastFreeRangeCoalesced); |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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|
7934 } |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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|
7935 |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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|
7936 #ifndef PRODUCT |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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|
7937 // Assertion checking only: no useful work in product mode -- |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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|
7938 // however, if any of the flags below become product flags, |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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|
7939 // you may need to review this code to see if it needs to be |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
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changeset
|
7940 // enabled in product mode. |
0 | 7941 SweepClosure::~SweepClosure() { |
7942 assert_lock_strong(_freelistLock); | |
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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|
7943 assert(_limit >= _sp->bottom() && _limit <= _sp->end(), |
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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diff
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|
7944 "sweep _limit out of bounds"); |
0 | 7945 if (inFreeRange()) { |
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
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changeset
|
7946 warning("inFreeRange() should have been reset; dumping state of SweepClosure"); |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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|
7947 print(); |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
7948 ShouldNotReachHere(); |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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|
7949 } |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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|
7950 if (Verbose && PrintGC) { |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
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|
7951 gclog_or_tty->print("Collected "SIZE_FORMAT" objects, " SIZE_FORMAT " bytes", |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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|
7952 _numObjectsFreed, _numWordsFreed*sizeof(HeapWord)); |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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|
7953 gclog_or_tty->print_cr("\nLive "SIZE_FORMAT" objects, " |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
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|
7954 SIZE_FORMAT" bytes " |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
7955 "Already free "SIZE_FORMAT" objects, "SIZE_FORMAT" bytes", |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
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|
7956 _numObjectsLive, _numWordsLive*sizeof(HeapWord), |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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|
7957 _numObjectsAlreadyFree, _numWordsAlreadyFree*sizeof(HeapWord)); |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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|
7958 size_t totalBytes = (_numWordsFreed + _numWordsLive + _numWordsAlreadyFree) |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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|
7959 * sizeof(HeapWord); |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
7960 gclog_or_tty->print_cr("Total sweep: "SIZE_FORMAT" bytes", totalBytes); |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
7961 |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
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|
7962 if (PrintCMSStatistics && CMSVerifyReturnedBytes) { |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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|
7963 size_t indexListReturnedBytes = _sp->sumIndexedFreeListArrayReturnedBytes(); |
6028
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
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6026
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|
7964 size_t dict_returned_bytes = _sp->dictionary()->sum_dict_returned_bytes(); |
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
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6026
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|
7965 size_t returned_bytes = indexListReturnedBytes + dict_returned_bytes; |
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
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6026
diff
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|
7966 gclog_or_tty->print("Returned "SIZE_FORMAT" bytes", returned_bytes); |
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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|
7967 gclog_or_tty->print(" Indexed List Returned "SIZE_FORMAT" bytes", |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
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|
7968 indexListReturnedBytes); |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
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changeset
|
7969 gclog_or_tty->print_cr(" Dictionary Returned "SIZE_FORMAT" bytes", |
6028
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
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6026
diff
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|
7970 dict_returned_bytes); |
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
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|
7971 } |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
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changeset
|
7972 } |
0 | 7973 if (CMSTraceSweeper) { |
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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|
7974 gclog_or_tty->print_cr("end of sweep with _limit = " PTR_FORMAT "\n================", |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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3356
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|
7975 _limit); |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
diff
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|
7976 } |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
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|
7977 } |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
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|
7978 #endif // PRODUCT |
0 | 7979 |
7980 void SweepClosure::initialize_free_range(HeapWord* freeFinger, | |
7981 bool freeRangeInFreeLists) { | |
7982 if (CMSTraceSweeper) { | |
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
changeset
|
7983 gclog_or_tty->print("---- Start free range at 0x%x with free block (%d)\n", |
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
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|
7984 freeFinger, freeRangeInFreeLists); |
0 | 7985 } |
7986 assert(!inFreeRange(), "Trampling existing free range"); | |
7987 set_inFreeRange(true); | |
7988 set_lastFreeRangeCoalesced(false); | |
7989 | |
7990 set_freeFinger(freeFinger); | |
7991 set_freeRangeInFreeLists(freeRangeInFreeLists); | |
7992 if (CMSTestInFreeList) { | |
7993 if (freeRangeInFreeLists) { | |
7994 FreeChunk* fc = (FreeChunk*) freeFinger; | |
6028
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7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
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6026
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|
7995 assert(fc->is_free(), "A chunk on the free list should be free."); |
0 | 7996 assert(fc->size() > 0, "Free range should have a size"); |
6028
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
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6026
diff
changeset
|
7997 assert(_sp->verify_chunk_in_free_list(fc), "Chunk is not in free lists"); |
0 | 7998 } |
7999 } | |
8000 } | |
8001 | |
8002 // Note that the sweeper runs concurrently with mutators. Thus, | |
8003 // it is possible for direct allocation in this generation to happen | |
8004 // in the middle of the sweep. Note that the sweeper also coalesces | |
8005 // contiguous free blocks. Thus, unless the sweeper and the allocator | |
8006 // synchronize appropriately freshly allocated blocks may get swept up. | |
8007 // This is accomplished by the sweeper locking the free lists while | |
8008 // it is sweeping. Thus blocks that are determined to be free are | |
8009 // indeed free. There is however one additional complication: | |
8010 // blocks that have been allocated since the final checkpoint and | |
8011 // mark, will not have been marked and so would be treated as | |
8012 // unreachable and swept up. To prevent this, the allocator marks | |
8013 // the bit map when allocating during the sweep phase. This leads, | |
8014 // however, to a further complication -- objects may have been allocated | |
8015 // but not yet initialized -- in the sense that the header isn't yet | |
8016 // installed. The sweeper can not then determine the size of the block | |
8017 // in order to skip over it. To deal with this case, we use a technique | |
8018 // (due to Printezis) to encode such uninitialized block sizes in the | |
8019 // bit map. Since the bit map uses a bit per every HeapWord, but the | |
8020 // CMS generation has a minimum object size of 3 HeapWords, it follows | |
8021 // that "normal marks" won't be adjacent in the bit map (there will | |
8022 // always be at least two 0 bits between successive 1 bits). We make use | |
8023 // of these "unused" bits to represent uninitialized blocks -- the bit | |
8024 // corresponding to the start of the uninitialized object and the next | |
8025 // bit are both set. Finally, a 1 bit marks the end of the object that | |
8026 // started with the two consecutive 1 bits to indicate its potentially | |
8027 // uninitialized state. | |
8028 | |
8029 size_t SweepClosure::do_blk_careful(HeapWord* addr) { | |
8030 FreeChunk* fc = (FreeChunk*)addr; | |
8031 size_t res; | |
8032 | |
1720
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
parents:
1716
diff
changeset
|
8033 // Check if we are done sweeping. Below we check "addr >= _limit" rather |
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
parents:
1716
diff
changeset
|
8034 // than "addr == _limit" because although _limit was a block boundary when |
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
parents:
1716
diff
changeset
|
8035 // 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
|
8036 // 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
|
8037 // 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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3356
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|
8038 // 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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3356
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changeset
|
8039 // see the following Zeno-like trail of CRs 6977970, 7008136, 7042740. |
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
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changeset
|
8040 if (addr >= _limit) { // we have swept up to or past the limit: finish up |
0 | 8041 assert(_limit >= _sp->bottom() && _limit <= _sp->end(), |
8042 "sweep _limit out of bounds"); | |
1720
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
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1716
diff
changeset
|
8043 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
|
8044 // Flush any free range we might be holding as a single |
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
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|
8045 // coalesced chunk to the appropriate free list. |
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
changeset
|
8046 if (inFreeRange()) { |
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
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changeset
|
8047 assert(freeFinger() >= _sp->bottom() && freeFinger() < _limit, |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
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|
8048 err_msg("freeFinger() " PTR_FORMAT" is out-of-bounds", freeFinger())); |
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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|
8049 flush_cur_free_chunk(freeFinger(), |
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
changeset
|
8050 pointer_delta(addr, freeFinger())); |
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
changeset
|
8051 if (CMSTraceSweeper) { |
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8052 gclog_or_tty->print("Sweep: last chunk: "); |
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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diff
changeset
|
8053 gclog_or_tty->print("put_free_blk 0x%x ("SIZE_FORMAT") " |
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8054 "[coalesced:"SIZE_FORMAT"]\n", |
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
changeset
|
8055 freeFinger(), pointer_delta(addr, freeFinger()), |
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8056 lastFreeRangeCoalesced()); |
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7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
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|
8057 } |
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
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|
8058 } |
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
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|
8059 |
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
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changeset
|
8060 // help the iterator loop finish |
1720
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
parents:
1716
diff
changeset
|
8061 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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|
8062 } |
2132
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7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
changeset
|
8063 |
1720
5ed703250bff
6977970: CMS: concurrentMarkSweepGeneration.cpp:7947 assert(addr <= _limit) failed: sweep invariant
ysr
parents:
1716
diff
changeset
|
8064 assert(addr < _limit, "sweep invariant"); |
0 | 8065 // check if we should yield |
8066 do_yield_check(addr); | |
6028
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
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6026
diff
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|
8067 if (fc->is_free()) { |
0 | 8068 // Chunk that is already free |
8069 res = fc->size(); | |
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8070 do_already_free_chunk(fc); |
0 | 8071 debug_only(_sp->verifyFreeLists()); |
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8072 // If we flush the chunk at hand in lookahead_and_flush() |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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changeset
|
8073 // 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
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changeset
|
8074 // process of "mangling" the payload of the coalesced block |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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changeset
|
8075 // will cause erasure of the size information from the |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8076 // (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
|
8077 // first, so the first disjunct in the assert will not hold |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
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changeset
|
8078 // 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
|
8079 // will hold). |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8080 assert(res == fc->size() || ((HeapWord*)fc) + res >= _limit, |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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changeset
|
8081 "Otherwise the size info doesn't change at this step"); |
0 | 8082 NOT_PRODUCT( |
8083 _numObjectsAlreadyFree++; | |
8084 _numWordsAlreadyFree += res; | |
8085 ) | |
8086 NOT_PRODUCT(_last_fc = fc;) | |
8087 } else if (!_bitMap->isMarked(addr)) { | |
8088 // Chunk is fresh garbage | |
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8089 res = do_garbage_chunk(fc); |
0 | 8090 debug_only(_sp->verifyFreeLists()); |
8091 NOT_PRODUCT( | |
8092 _numObjectsFreed++; | |
8093 _numWordsFreed += res; | |
8094 ) | |
8095 } else { | |
8096 // Chunk that is alive. | |
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8097 res = do_live_chunk(fc); |
0 | 8098 debug_only(_sp->verifyFreeLists()); |
8099 NOT_PRODUCT( | |
8100 _numObjectsLive++; | |
8101 _numWordsLive += res; | |
8102 ) | |
8103 } | |
8104 return res; | |
8105 } | |
8106 | |
8107 // For the smart allocation, record following | |
8108 // split deaths - a free chunk is removed from its free list because | |
8109 // it is being split into two or more chunks. | |
8110 // split birth - a free chunk is being added to its free list because | |
8111 // a larger free chunk has been split and resulted in this free chunk. | |
8112 // coal death - a free chunk is being removed from its free list because | |
8113 // it is being coalesced into a large free chunk. | |
8114 // coal birth - a free chunk is being added to its free list because | |
8115 // it was created when two or more free chunks where coalesced into | |
8116 // this free chunk. | |
8117 // | |
8118 // These statistics are used to determine the desired number of free | |
8119 // chunks of a given size. The desired number is chosen to be relative | |
8120 // to the end of a CMS sweep. The desired number at the end of a sweep | |
8121 // is the | |
8122 // count-at-end-of-previous-sweep (an amount that was enough) | |
8123 // - count-at-beginning-of-current-sweep (the excess) | |
8124 // + split-births (gains in this size during interval) | |
8125 // - split-deaths (demands on this size during interval) | |
8126 // where the interval is from the end of one sweep to the end of the | |
8127 // next. | |
8128 // | |
8129 // When sweeping the sweeper maintains an accumulated chunk which is | |
8130 // the chunk that is made up of chunks that have been coalesced. That | |
8131 // will be termed the left-hand chunk. A new chunk of garbage that | |
8132 // is being considered for coalescing will be referred to as the | |
8133 // right-hand chunk. | |
8134 // | |
8135 // When making a decision on whether to coalesce a right-hand chunk with | |
8136 // the current left-hand chunk, the current count vs. the desired count | |
8137 // of the left-hand chunk is considered. Also if the right-hand chunk | |
8138 // is near the large chunk at the end of the heap (see | |
8139 // ConcurrentMarkSweepGeneration::isNearLargestChunk()), then the | |
8140 // left-hand chunk is coalesced. | |
8141 // | |
8142 // When making a decision about whether to split a chunk, the desired count | |
8143 // vs. the current count of the candidate to be split is also considered. | |
8144 // If the candidate is underpopulated (currently fewer chunks than desired) | |
8145 // a chunk of an overpopulated (currently more chunks than desired) size may | |
8146 // be chosen. The "hint" associated with a free list, if non-null, points | |
8147 // to a free list which may be overpopulated. | |
8148 // | |
8149 | |
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
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|
8150 void SweepClosure::do_already_free_chunk(FreeChunk* fc) { |
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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|
8151 const size_t size = fc->size(); |
0 | 8152 // Chunks that cannot be coalesced are not in the |
8153 // free lists. | |
8154 if (CMSTestInFreeList && !fc->cantCoalesce()) { | |
6028
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7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
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6026
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|
8155 assert(_sp->verify_chunk_in_free_list(fc), |
0 | 8156 "free chunk should be in free lists"); |
8157 } | |
8158 // a chunk that is already free, should not have been | |
8159 // marked in the bit map | |
3746
537a4053b0f9
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ysr
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3356
diff
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|
8160 HeapWord* const addr = (HeapWord*) fc; |
0 | 8161 assert(!_bitMap->isMarked(addr), "free chunk should be unmarked"); |
8162 // Verify that the bit map has no bits marked between | |
8163 // addr and purported end of this block. | |
8164 _bitMap->verifyNoOneBitsInRange(addr + 1, addr + size); | |
8165 | |
2132
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7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
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|
8166 // Some chunks cannot be coalesced under any circumstances. |
0 | 8167 // See the definition of cantCoalesce(). |
8168 if (!fc->cantCoalesce()) { | |
8169 // This chunk can potentially be coalesced. | |
8170 if (_sp->adaptive_freelists()) { | |
8171 // All the work is done in | |
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
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|
8172 do_post_free_or_garbage_chunk(fc, size); |
0 | 8173 } else { // Not adaptive free lists |
8174 // this is a free chunk that can potentially be coalesced by the sweeper; | |
8175 if (!inFreeRange()) { | |
8176 // if the next chunk is a free block that can't be coalesced | |
8177 // it doesn't make sense to remove this chunk from the free lists | |
8178 FreeChunk* nextChunk = (FreeChunk*)(addr + size); | |
2136
c91cc404ca46
7011940: iCMS: SIGSEGV in SweepClosure::do_already_free_chunk(FreeChunk*)+0x360
ysr
parents:
2132
diff
changeset
|
8179 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
|
8180 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
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|
8181 nextChunk->is_free() && // ... which is free... |
2136
c91cc404ca46
7011940: iCMS: SIGSEGV in SweepClosure::do_already_free_chunk(FreeChunk*)+0x360
ysr
parents:
2132
diff
changeset
|
8182 nextChunk->cantCoalesce()) { // ... but can't be coalesced |
0 | 8183 // nothing to do |
8184 } else { | |
8185 // Potentially the start of a new free range: | |
8186 // Don't eagerly remove it from the free lists. | |
8187 // No need to remove it if it will just be put | |
8188 // back again. (Also from a pragmatic point of view | |
8189 // if it is a free block in a region that is beyond | |
8190 // any allocated blocks, an assertion will fail) | |
8191 // Remember the start of a free run. | |
8192 initialize_free_range(addr, true); | |
8193 // end - can coalesce with next chunk | |
8194 } | |
8195 } else { | |
8196 // 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
|
8197 print_free_block_coalesced(fc); |
0 | 8198 if (CMSTraceSweeper) { |
8199 gclog_or_tty->print(" -- pick up free block 0x%x (%d)\n", fc, size); | |
8200 } | |
8201 // remove it from the free lists | |
8202 _sp->removeFreeChunkFromFreeLists(fc); | |
8203 set_lastFreeRangeCoalesced(true); | |
8204 // If the chunk is being coalesced and the current free range is | |
8205 // in the free lists, remove the current free range so that it | |
8206 // will be returned to the free lists in its entirety - all | |
8207 // the coalesced pieces included. | |
8208 if (freeRangeInFreeLists()) { | |
8209 FreeChunk* ffc = (FreeChunk*) freeFinger(); | |
8210 assert(ffc->size() == pointer_delta(addr, freeFinger()), | |
8211 "Size of free range is inconsistent with chunk size."); | |
8212 if (CMSTestInFreeList) { | |
6028
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
parents:
6026
diff
changeset
|
8213 assert(_sp->verify_chunk_in_free_list(ffc), |
0 | 8214 "free range is not in free lists"); |
8215 } | |
8216 _sp->removeFreeChunkFromFreeLists(ffc); | |
8217 set_freeRangeInFreeLists(false); | |
8218 } | |
8219 } | |
8220 } | |
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8221 // 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
|
8222 // 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
|
8223 // a "lookahead," as we do below. |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8224 if (inFreeRange()) lookahead_and_flush(fc, size); |
0 | 8225 } else { |
8226 // Code path common to both original and adaptive free lists. | |
8227 | |
8228 // cant coalesce with previous block; this should be treated | |
8229 // as the end of a free run if any | |
8230 if (inFreeRange()) { | |
8231 // 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
|
8232 assert(freeFinger() < addr, "freeFinger points too high"); |
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8233 flush_cur_free_chunk(freeFinger(), pointer_delta(addr, freeFinger())); |
0 | 8234 } |
8235 // else, nothing to do, just continue | |
8236 } | |
8237 } | |
8238 | |
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
parents:
1994
diff
changeset
|
8239 size_t SweepClosure::do_garbage_chunk(FreeChunk* fc) { |
0 | 8240 // This is a chunk of garbage. It is not in any free list. |
8241 // Add it to a free list or let it possibly be coalesced into | |
8242 // a larger chunk. | |
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8243 HeapWord* const addr = (HeapWord*) fc; |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8244 const size_t size = CompactibleFreeListSpace::adjustObjectSize(oop(addr)->size()); |
0 | 8245 |
8246 if (_sp->adaptive_freelists()) { | |
8247 // Verify that the bit map has no bits marked between | |
8248 // addr and purported end of just dead object. | |
8249 _bitMap->verifyNoOneBitsInRange(addr + 1, addr + size); | |
8250 | |
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
changeset
|
8251 do_post_free_or_garbage_chunk(fc, size); |
0 | 8252 } else { |
8253 if (!inFreeRange()) { | |
8254 // start of a new free range | |
8255 assert(size > 0, "A free range should have a size"); | |
8256 initialize_free_range(addr, false); | |
8257 } else { | |
8258 // this will be swept up when we hit the end of the | |
8259 // free range | |
8260 if (CMSTraceSweeper) { | |
8261 gclog_or_tty->print(" -- pick up garbage 0x%x (%d) \n", fc, size); | |
8262 } | |
8263 // If the chunk is being coalesced and the current free range is | |
8264 // in the free lists, remove the current free range so that it | |
8265 // will be returned to the free lists in its entirety - all | |
8266 // the coalesced pieces included. | |
8267 if (freeRangeInFreeLists()) { | |
8268 FreeChunk* ffc = (FreeChunk*)freeFinger(); | |
8269 assert(ffc->size() == pointer_delta(addr, freeFinger()), | |
8270 "Size of free range is inconsistent with chunk size."); | |
8271 if (CMSTestInFreeList) { | |
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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|
8272 assert(_sp->verify_chunk_in_free_list(ffc), |
0 | 8273 "free range is not in free lists"); |
8274 } | |
8275 _sp->removeFreeChunkFromFreeLists(ffc); | |
8276 set_freeRangeInFreeLists(false); | |
8277 } | |
8278 set_lastFreeRangeCoalesced(true); | |
8279 } | |
8280 // this will be swept up when we hit the end of the free range | |
8281 | |
8282 // Verify that the bit map has no bits marked between | |
8283 // addr and purported end of just dead object. | |
8284 _bitMap->verifyNoOneBitsInRange(addr + 1, addr + size); | |
8285 } | |
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8286 assert(_limit >= addr + size, |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
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|
8287 "A freshly garbage chunk can't possibly straddle over _limit"); |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8288 if (inFreeRange()) lookahead_and_flush(fc, size); |
0 | 8289 return size; |
8290 } | |
8291 | |
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
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|
8292 size_t SweepClosure::do_live_chunk(FreeChunk* fc) { |
0 | 8293 HeapWord* addr = (HeapWord*) fc; |
8294 // The sweeper has just found a live object. Return any accumulated | |
8295 // left hand chunk to the free lists. | |
8296 if (inFreeRange()) { | |
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
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|
8297 assert(freeFinger() < addr, "freeFinger points too high"); |
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
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|
8298 flush_cur_free_chunk(freeFinger(), pointer_delta(addr, freeFinger())); |
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
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|
8299 } |
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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1994
diff
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|
8300 |
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
ysr
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diff
changeset
|
8301 // This object is live: we'd normally expect this to be |
0 | 8302 // an oop, and like to assert the following: |
8303 // assert(oop(addr)->is_oop(), "live block should be an oop"); | |
8304 // However, as we commented above, this may be an object whose | |
8305 // header hasn't yet been initialized. | |
8306 size_t size; | |
8307 assert(_bitMap->isMarked(addr), "Tautology for this control point"); | |
8308 if (_bitMap->isMarked(addr + 1)) { | |
8309 // Determine the size from the bit map, rather than trying to | |
8310 // compute it from the object header. | |
8311 HeapWord* nextOneAddr = _bitMap->getNextMarkedWordAddress(addr + 2); | |
8312 size = pointer_delta(nextOneAddr + 1, addr); | |
8313 assert(size == CompactibleFreeListSpace::adjustObjectSize(size), | |
8314 "alignment problem"); | |
8315 | |
9152 | 8316 #ifdef ASSERT |
6725
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
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|
8317 if (oop(addr)->klass_or_null() != NULL) { |
0 | 8318 // Ignore mark word because we are running concurrent with mutators |
8319 assert(oop(addr)->is_oop(true), "live block should be an oop"); | |
8320 assert(size == | |
8321 CompactibleFreeListSpace::adjustObjectSize(oop(addr)->size()), | |
8322 "P-mark and computed size do not agree"); | |
8323 } | |
2132
4947ee68d19c
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ysr
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1994
diff
changeset
|
8324 #endif |
0 | 8325 |
8326 } else { | |
8327 // This should be an initialized object that's alive. | |
6725
da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
6197
diff
changeset
|
8328 assert(oop(addr)->klass_or_null() != NULL, |
0 | 8329 "Should be an initialized object"); |
8330 // Ignore mark word because we are running concurrent with mutators | |
8331 assert(oop(addr)->is_oop(true), "live block should be an oop"); | |
8332 // Verify that the bit map has no bits marked between | |
8333 // addr and purported end of this block. | |
8334 size = CompactibleFreeListSpace::adjustObjectSize(oop(addr)->size()); | |
8335 assert(size >= 3, "Necessary for Printezis marks to work"); | |
8336 assert(!_bitMap->isMarked(addr+1), "Tautology for this control point"); | |
8337 DEBUG_ONLY(_bitMap->verifyNoOneBitsInRange(addr+2, addr+size);) | |
8338 } | |
8339 return size; | |
8340 } | |
8341 | |
2132
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|
8342 void SweepClosure::do_post_free_or_garbage_chunk(FreeChunk* fc, |
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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|
8343 size_t chunkSize) { |
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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diff
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|
8344 // 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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|
8345 // of the adaptive free list allocator. |
6028
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|
8346 const bool fcInFreeLists = fc->is_free(); |
0 | 8347 assert(_sp->adaptive_freelists(), "Should only be used in this case."); |
8348 assert((HeapWord*)fc <= _limit, "sweep invariant"); | |
8349 if (CMSTestInFreeList && fcInFreeLists) { | |
6028
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|
8350 assert(_sp->verify_chunk_in_free_list(fc), "free chunk is not in free lists"); |
2132
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|
8351 } |
0 | 8352 |
8353 if (CMSTraceSweeper) { | |
8354 gclog_or_tty->print_cr(" -- pick up another chunk at 0x%x (%d)", fc, chunkSize); | |
8355 } | |
8356 | |
3746
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|
8357 HeapWord* const fc_addr = (HeapWord*) fc; |
0 | 8358 |
8359 bool coalesce; | |
3746
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|
8360 const size_t left = pointer_delta(fc_addr, freeFinger()); |
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|
8361 const size_t right = chunkSize; |
0 | 8362 switch (FLSCoalescePolicy) { |
8363 // numeric value forms a coalition aggressiveness metric | |
8364 case 0: { // never coalesce | |
8365 coalesce = false; | |
8366 break; | |
8367 } | |
8368 case 1: { // coalesce if left & right chunks on overpopulated lists | |
8369 coalesce = _sp->coalOverPopulated(left) && | |
8370 _sp->coalOverPopulated(right); | |
8371 break; | |
8372 } | |
8373 case 2: { // coalesce if left chunk on overpopulated list (default) | |
8374 coalesce = _sp->coalOverPopulated(left); | |
8375 break; | |
8376 } | |
8377 case 3: { // coalesce if left OR right chunk on overpopulated list | |
8378 coalesce = _sp->coalOverPopulated(left) || | |
8379 _sp->coalOverPopulated(right); | |
8380 break; | |
8381 } | |
8382 case 4: { // always coalesce | |
8383 coalesce = true; | |
8384 break; | |
8385 } | |
8386 default: | |
8387 ShouldNotReachHere(); | |
8388 } | |
8389 | |
8390 // Should the current free range be coalesced? | |
8391 // If the chunk is in a free range and either we decided to coalesce above | |
8392 // or the chunk is near the large block at the end of the heap | |
8393 // (isNearLargestChunk() returns true), then coalesce this chunk. | |
3746
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|
8394 const bool doCoalesce = inFreeRange() |
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|
8395 && (coalesce || _g->isNearLargestChunk(fc_addr)); |
0 | 8396 if (doCoalesce) { |
8397 // Coalesce the current free range on the left with the new | |
8398 // chunk on the right. If either is on a free list, | |
8399 // it must be removed from the list and stashed in the closure. | |
8400 if (freeRangeInFreeLists()) { | |
3746
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|
8401 FreeChunk* const ffc = (FreeChunk*)freeFinger(); |
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|
8402 assert(ffc->size() == pointer_delta(fc_addr, freeFinger()), |
0 | 8403 "Size of free range is inconsistent with chunk size."); |
8404 if (CMSTestInFreeList) { | |
6028
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|
8405 assert(_sp->verify_chunk_in_free_list(ffc), |
0 | 8406 "Chunk is not in free lists"); |
8407 } | |
8408 _sp->coalDeath(ffc->size()); | |
8409 _sp->removeFreeChunkFromFreeLists(ffc); | |
8410 set_freeRangeInFreeLists(false); | |
8411 } | |
8412 if (fcInFreeLists) { | |
8413 _sp->coalDeath(chunkSize); | |
8414 assert(fc->size() == chunkSize, | |
8415 "The chunk has the wrong size or is not in the free lists"); | |
8416 _sp->removeFreeChunkFromFreeLists(fc); | |
8417 } | |
8418 set_lastFreeRangeCoalesced(true); | |
3746
537a4053b0f9
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|
8419 print_free_block_coalesced(fc); |
0 | 8420 } else { // not in a free range and/or should not coalesce |
8421 // Return the current free range and start a new one. | |
8422 if (inFreeRange()) { | |
8423 // In a free range but cannot coalesce with the right hand chunk. | |
8424 // Put the current free range into the free lists. | |
2132
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1994
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|
8425 flush_cur_free_chunk(freeFinger(), |
3746
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7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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changeset
|
8426 pointer_delta(fc_addr, freeFinger())); |
0 | 8427 } |
8428 // Set up for new free range. Pass along whether the right hand | |
8429 // chunk is in the free lists. | |
8430 initialize_free_range((HeapWord*)fc, fcInFreeLists); | |
8431 } | |
8432 } | |
2132
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|
8433 |
3746
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|
8434 // Lookahead flush: |
537a4053b0f9
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|
8435 // If we are tracking a free range, and this is the last chunk that |
537a4053b0f9
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|
8436 // we'll look at because its end crosses past _limit, we'll preemptively |
537a4053b0f9
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ysr
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|
8437 // flush it along with any free range we may be holding on to. Note that |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
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|
8438 // this can be the case only for an already free or freshly garbage |
537a4053b0f9
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|
8439 // chunk. If this block is an object, it can never straddle |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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|
8440 // over _limit. The "straddling" occurs when _limit is set at |
537a4053b0f9
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ysr
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|
8441 // the previous end of the space when this cycle started, and |
537a4053b0f9
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ysr
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|
8442 // a subsequent heap expansion caused the previously co-terminal |
537a4053b0f9
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ysr
parents:
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|
8443 // free block to be coalesced with the newly expanded portion, |
537a4053b0f9
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ysr
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|
8444 // thus rendering _limit a non-block-boundary making it dangerous |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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|
8445 // for the sweeper to step over and examine. |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
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|
8446 void SweepClosure::lookahead_and_flush(FreeChunk* fc, size_t chunk_size) { |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
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|
8447 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
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|
8448 HeapWord* const eob = ((HeapWord*)fc) + chunk_size; |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
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|
8449 assert(_sp->used_region().contains(eob - 1), |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
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|
8450 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
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|
8451 " when examining fc = " PTR_FORMAT "(" SIZE_FORMAT ")", |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
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|
8452 _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
|
8453 if (eob >= _limit) { |
6028
f69a5d43dc19
7164144: Fix variable naming style in freeBlockDictionary.* and binaryTreeDictionary*
jmasa
parents:
6026
diff
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|
8454 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
|
8455 if (CMSTraceSweeper) { |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8456 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
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|
8457 "[" PTR_FORMAT "," PTR_FORMAT ") in space " |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8458 "[" PTR_FORMAT "," PTR_FORMAT ")", |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8459 _limit, fc, eob, _sp->bottom(), _sp->end()); |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
diff
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|
8460 } |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
diff
changeset
|
8461 // 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
|
8462 if (CMSTraceSweeper) { |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8463 gclog_or_tty->print_cr("Flushing ... "); |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
diff
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|
8464 } |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
parents:
3356
diff
changeset
|
8465 assert(freeFinger() < eob, "Error"); |
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
diff
changeset
|
8466 flush_cur_free_chunk( freeFinger(), pointer_delta(eob, freeFinger())); |
537a4053b0f9
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ysr
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|
8467 } |
537a4053b0f9
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ysr
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3356
diff
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|
8468 } |
537a4053b0f9
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ysr
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3356
diff
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|
8469 |
2132
4947ee68d19c
7008136: CMS: assert((HeapWord*)nextChunk <= _limit) failed: sweep invariant
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1994
diff
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|
8470 void SweepClosure::flush_cur_free_chunk(HeapWord* chunk, size_t size) { |
0 | 8471 assert(inFreeRange(), "Should only be called if currently in a free range."); |
8472 assert(size > 0, | |
8473 "A zero sized chunk cannot be added to the free lists."); | |
8474 if (!freeRangeInFreeLists()) { | |
2132
4947ee68d19c
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ysr
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1994
diff
changeset
|
8475 if (CMSTestInFreeList) { |
0 | 8476 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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|
8477 fc->set_size(size); |
f69a5d43dc19
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jmasa
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6026
diff
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|
8478 assert(!_sp->verify_chunk_in_free_list(fc), |
0 | 8479 "chunk should not be in free lists yet"); |
8480 } | |
8481 if (CMSTraceSweeper) { | |
8482 gclog_or_tty->print_cr(" -- add free block 0x%x (%d) to free lists", | |
8483 chunk, size); | |
8484 } | |
8485 // A new free range is going to be starting. The current | |
8486 // free range has not been added to the free lists yet or | |
8487 // was removed so add it back. | |
8488 // If the current free range was coalesced, then the death | |
8489 // of the free range was recorded. Record a birth now. | |
8490 if (lastFreeRangeCoalesced()) { | |
8491 _sp->coalBirth(size); | |
8492 } | |
8493 _sp->addChunkAndRepairOffsetTable(chunk, size, | |
8494 lastFreeRangeCoalesced()); | |
3746
537a4053b0f9
7042740: CMS: assert(n> q) failed: Looping at: ... blockOffsetTable.cpp:557
ysr
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3356
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|
8495 } else if (CMSTraceSweeper) { |
537a4053b0f9
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ysr
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diff
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|
8496 gclog_or_tty->print_cr("Already in free list: nothing to flush"); |
0 | 8497 } |
8498 set_inFreeRange(false); | |
8499 set_freeRangeInFreeLists(false); | |
8500 } | |
8501 | |
8502 // We take a break if we've been at this for a while, | |
8503 // so as to avoid monopolizing the locks involved. | |
8504 void SweepClosure::do_yield_work(HeapWord* addr) { | |
8505 // Return current free chunk being used for coalescing (if any) | |
8506 // to the appropriate freelist. After yielding, the next | |
8507 // free block encountered will start a coalescing range of | |
8508 // free blocks. If the next free block is adjacent to the | |
8509 // chunk just flushed, they will need to wait for the next | |
8510 // sweep to be coalesced. | |
8511 if (inFreeRange()) { | |
2132
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ysr
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1994
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|
8512 flush_cur_free_chunk(freeFinger(), pointer_delta(addr, freeFinger())); |
0 | 8513 } |
8514 | |
8515 // First give up the locks, then yield, then re-lock. | |
8516 // We should probably use a constructor/destructor idiom to | |
8517 // do this unlock/lock or modify the MutexUnlocker class to | |
8518 // serve our purpose. XXX | |
8519 assert_lock_strong(_bitMap->lock()); | |
8520 assert_lock_strong(_freelistLock); | |
8521 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
8522 "CMS thread should hold CMS token"); | |
8523 _bitMap->lock()->unlock(); | |
8524 _freelistLock->unlock(); | |
8525 ConcurrentMarkSweepThread::desynchronize(true); | |
8526 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
8527 _collector->stopTimer(); | |
8528 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
8529 if (PrintCMSStatistics != 0) { | |
8530 _collector->incrementYields(); | |
8531 } | |
8532 _collector->icms_wait(); | |
8533 | |
8534 // See the comment in coordinator_yield() | |
8535 for (unsigned i = 0; i < CMSYieldSleepCount && | |
8536 ConcurrentMarkSweepThread::should_yield() && | |
8537 !CMSCollector::foregroundGCIsActive(); ++i) { | |
8538 os::sleep(Thread::current(), 1, false); | |
8539 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
8540 } | |
8541 | |
8542 ConcurrentMarkSweepThread::synchronize(true); | |
8543 _freelistLock->lock(); | |
8544 _bitMap->lock()->lock_without_safepoint_check(); | |
8545 _collector->startTimer(); | |
8546 } | |
8547 | |
8548 #ifndef PRODUCT | |
8549 // This is actually very useful in a product build if it can | |
8550 // be called from the debugger. Compile it into the product | |
8551 // as needed. | |
6028
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|
8552 bool debug_verify_chunk_in_free_list(FreeChunk* fc) { |
f69a5d43dc19
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6026
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|
8553 return debug_cms_space->verify_chunk_in_free_list(fc); |
0 | 8554 } |
3746
537a4053b0f9
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ysr
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|
8555 #endif |
537a4053b0f9
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ysr
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|
8556 |
537a4053b0f9
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ysr
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|
8557 void SweepClosure::print_free_block_coalesced(FreeChunk* fc) const { |
0 | 8558 if (CMSTraceSweeper) { |
3746
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3356
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|
8559 gclog_or_tty->print_cr("Sweep:coal_free_blk " PTR_FORMAT " (" SIZE_FORMAT ")", |
537a4053b0f9
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|
8560 fc, fc->size()); |
537a4053b0f9
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|
8561 } |
537a4053b0f9
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|
8562 } |
0 | 8563 |
8564 // CMSIsAliveClosure | |
8565 bool CMSIsAliveClosure::do_object_b(oop obj) { | |
8566 HeapWord* addr = (HeapWord*)obj; | |
8567 return addr != NULL && | |
8568 (!_span.contains(addr) || _bit_map->isMarked(addr)); | |
8569 } | |
8570 | |
6725
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8571 |
935 | 8572 CMSKeepAliveClosure::CMSKeepAliveClosure( CMSCollector* collector, |
8573 MemRegion span, | |
8574 CMSBitMap* bit_map, CMSMarkStack* mark_stack, | |
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8575 bool cpc): |
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8576 _collector(collector), |
935 | 8577 _span(span), |
8578 _bit_map(bit_map), | |
8579 _mark_stack(mark_stack), | |
8580 _concurrent_precleaning(cpc) { | |
8581 assert(!_span.is_empty(), "Empty span could spell trouble"); | |
8582 } | |
8583 | |
8584 | |
0 | 8585 // CMSKeepAliveClosure: the serial version |
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8586 void CMSKeepAliveClosure::do_oop(oop obj) { |
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8587 HeapWord* addr = (HeapWord*)obj; |
0 | 8588 if (_span.contains(addr) && |
8589 !_bit_map->isMarked(addr)) { | |
8590 _bit_map->mark(addr); | |
8591 bool simulate_overflow = false; | |
8592 NOT_PRODUCT( | |
8593 if (CMSMarkStackOverflowALot && | |
8594 _collector->simulate_overflow()) { | |
8595 // simulate a stack overflow | |
8596 simulate_overflow = true; | |
8597 } | |
8598 ) | |
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8599 if (simulate_overflow || !_mark_stack->push(obj)) { |
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8600 if (_concurrent_precleaning) { |
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8601 // We dirty the overflown object and let the remark |
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8602 // phase deal with it. |
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8603 assert(_collector->overflow_list_is_empty(), "Error"); |
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8604 // In the case of object arrays, we need to dirty all of |
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8605 // the cards that the object spans. No locking or atomics |
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8606 // are needed since no one else can be mutating the mod union |
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8607 // table. |
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8608 if (obj->is_objArray()) { |
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8609 size_t sz = obj->size(); |
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8610 HeapWord* end_card_addr = |
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8611 (HeapWord*)round_to((intptr_t)(addr+sz), CardTableModRefBS::card_size); |
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8612 MemRegion redirty_range = MemRegion(addr, end_card_addr); |
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8613 assert(!redirty_range.is_empty(), "Arithmetical tautology"); |
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8614 _collector->_modUnionTable.mark_range(redirty_range); |
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8615 } else { |
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8616 _collector->_modUnionTable.mark(addr); |
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8617 } |
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8618 _collector->_ser_kac_preclean_ovflw++; |
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8619 } else { |
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8620 _collector->push_on_overflow_list(obj); |
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8621 _collector->_ser_kac_ovflw++; |
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8622 } |
0 | 8623 } |
8624 } | |
8625 } | |
8626 | |
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8627 void CMSKeepAliveClosure::do_oop(oop* p) { CMSKeepAliveClosure::do_oop_work(p); } |
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8628 void CMSKeepAliveClosure::do_oop(narrowOop* p) { CMSKeepAliveClosure::do_oop_work(p); } |
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8629 |
0 | 8630 // CMSParKeepAliveClosure: a parallel version of the above. |
8631 // The work queues are private to each closure (thread), | |
8632 // but (may be) available for stealing by other threads. | |
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8633 void CMSParKeepAliveClosure::do_oop(oop obj) { |
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8634 HeapWord* addr = (HeapWord*)obj; |
0 | 8635 if (_span.contains(addr) && |
8636 !_bit_map->isMarked(addr)) { | |
8637 // In general, during recursive tracing, several threads | |
8638 // may be concurrently getting here; the first one to | |
8639 // "tag" it, claims it. | |
8640 if (_bit_map->par_mark(addr)) { | |
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8641 bool res = _work_queue->push(obj); |
0 | 8642 assert(res, "Low water mark should be much less than capacity"); |
8643 // Do a recursive trim in the hope that this will keep | |
8644 // stack usage lower, but leave some oops for potential stealers | |
8645 trim_queue(_low_water_mark); | |
8646 } // Else, another thread got there first | |
8647 } | |
8648 } | |
8649 | |
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8650 void CMSParKeepAliveClosure::do_oop(oop* p) { CMSParKeepAliveClosure::do_oop_work(p); } |
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8651 void CMSParKeepAliveClosure::do_oop(narrowOop* p) { CMSParKeepAliveClosure::do_oop_work(p); } |
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8652 |
0 | 8653 void CMSParKeepAliveClosure::trim_queue(uint max) { |
8654 while (_work_queue->size() > max) { | |
8655 oop new_oop; | |
8656 if (_work_queue->pop_local(new_oop)) { | |
8657 assert(new_oop != NULL && new_oop->is_oop(), "Expected an oop"); | |
8658 assert(_bit_map->isMarked((HeapWord*)new_oop), | |
8659 "no white objects on this stack!"); | |
8660 assert(_span.contains((HeapWord*)new_oop), "Out of bounds oop"); | |
8661 // iterate over the oops in this oop, marking and pushing | |
8662 // the ones in CMS heap (i.e. in _span). | |
8663 new_oop->oop_iterate(&_mark_and_push); | |
8664 } | |
8665 } | |
8666 } | |
8667 | |
935 | 8668 CMSInnerParMarkAndPushClosure::CMSInnerParMarkAndPushClosure( |
8669 CMSCollector* collector, | |
8670 MemRegion span, CMSBitMap* bit_map, | |
8671 OopTaskQueue* work_queue): | |
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8672 _collector(collector), |
935 | 8673 _span(span), |
8674 _bit_map(bit_map), | |
8675 _work_queue(work_queue) { } | |
8676 | |
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8677 void CMSInnerParMarkAndPushClosure::do_oop(oop obj) { |
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8678 HeapWord* addr = (HeapWord*)obj; |
0 | 8679 if (_span.contains(addr) && |
8680 !_bit_map->isMarked(addr)) { | |
8681 if (_bit_map->par_mark(addr)) { | |
8682 bool simulate_overflow = false; | |
8683 NOT_PRODUCT( | |
8684 if (CMSMarkStackOverflowALot && | |
8685 _collector->par_simulate_overflow()) { | |
8686 // simulate a stack overflow | |
8687 simulate_overflow = true; | |
8688 } | |
8689 ) | |
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8690 if (simulate_overflow || !_work_queue->push(obj)) { |
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8691 _collector->par_push_on_overflow_list(obj); |
0 | 8692 _collector->_par_kac_ovflw++; |
8693 } | |
8694 } // Else another thread got there already | |
8695 } | |
8696 } | |
8697 | |
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8698 void CMSInnerParMarkAndPushClosure::do_oop(oop* p) { CMSInnerParMarkAndPushClosure::do_oop_work(p); } |
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8699 void CMSInnerParMarkAndPushClosure::do_oop(narrowOop* p) { CMSInnerParMarkAndPushClosure::do_oop_work(p); } |
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8700 |
0 | 8701 ////////////////////////////////////////////////////////////////// |
8702 // CMSExpansionCause ///////////////////////////// | |
8703 ////////////////////////////////////////////////////////////////// | |
8704 const char* CMSExpansionCause::to_string(CMSExpansionCause::Cause cause) { | |
8705 switch (cause) { | |
8706 case _no_expansion: | |
8707 return "No expansion"; | |
8708 case _satisfy_free_ratio: | |
8709 return "Free ratio"; | |
8710 case _satisfy_promotion: | |
8711 return "Satisfy promotion"; | |
8712 case _satisfy_allocation: | |
8713 return "allocation"; | |
8714 case _allocate_par_lab: | |
8715 return "Par LAB"; | |
8716 case _allocate_par_spooling_space: | |
8717 return "Par Spooling Space"; | |
8718 case _adaptive_size_policy: | |
8719 return "Ergonomics"; | |
8720 default: | |
8721 return "unknown"; | |
8722 } | |
8723 } | |
8724 | |
8725 void CMSDrainMarkingStackClosure::do_void() { | |
8726 // the max number to take from overflow list at a time | |
8727 const size_t num = _mark_stack->capacity()/4; | |
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8728 assert(!_concurrent_precleaning || _collector->overflow_list_is_empty(), |
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8729 "Overflow list should be NULL during concurrent phases"); |
0 | 8730 while (!_mark_stack->isEmpty() || |
8731 // if stack is empty, check the overflow list | |
8732 _collector->take_from_overflow_list(num, _mark_stack)) { | |
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8733 oop obj = _mark_stack->pop(); |
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8734 HeapWord* addr = (HeapWord*)obj; |
0 | 8735 assert(_span.contains(addr), "Should be within span"); |
8736 assert(_bit_map->isMarked(addr), "Should be marked"); | |
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8737 assert(obj->is_oop(), "Should be an oop"); |
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8738 obj->oop_iterate(_keep_alive); |
0 | 8739 } |
8740 } | |
8741 | |
8742 void CMSParDrainMarkingStackClosure::do_void() { | |
8743 // drain queue | |
8744 trim_queue(0); | |
8745 } | |
8746 | |
8747 // Trim our work_queue so its length is below max at return | |
8748 void CMSParDrainMarkingStackClosure::trim_queue(uint max) { | |
8749 while (_work_queue->size() > max) { | |
8750 oop new_oop; | |
8751 if (_work_queue->pop_local(new_oop)) { | |
8752 assert(new_oop->is_oop(), "Expected an oop"); | |
8753 assert(_bit_map->isMarked((HeapWord*)new_oop), | |
8754 "no white objects on this stack!"); | |
8755 assert(_span.contains((HeapWord*)new_oop), "Out of bounds oop"); | |
8756 // iterate over the oops in this oop, marking and pushing | |
8757 // the ones in CMS heap (i.e. in _span). | |
8758 new_oop->oop_iterate(&_mark_and_push); | |
8759 } | |
8760 } | |
8761 } | |
8762 | |
8763 //////////////////////////////////////////////////////////////////// | |
8764 // Support for Marking Stack Overflow list handling and related code | |
8765 //////////////////////////////////////////////////////////////////// | |
8766 // Much of the following code is similar in shape and spirit to the | |
8767 // code used in ParNewGC. We should try and share that code | |
8768 // as much as possible in the future. | |
8769 | |
8770 #ifndef PRODUCT | |
8771 // Debugging support for CMSStackOverflowALot | |
8772 | |
8773 // It's OK to call this multi-threaded; the worst thing | |
8774 // that can happen is that we'll get a bunch of closely | |
8775 // spaced simulated oveflows, but that's OK, in fact | |
8776 // probably good as it would exercise the overflow code | |
8777 // under contention. | |
8778 bool CMSCollector::simulate_overflow() { | |
8779 if (_overflow_counter-- <= 0) { // just being defensive | |
8780 _overflow_counter = CMSMarkStackOverflowInterval; | |
8781 return true; | |
8782 } else { | |
8783 return false; | |
8784 } | |
8785 } | |
8786 | |
8787 bool CMSCollector::par_simulate_overflow() { | |
8788 return simulate_overflow(); | |
8789 } | |
8790 #endif | |
8791 | |
8792 // Single-threaded | |
8793 bool CMSCollector::take_from_overflow_list(size_t num, CMSMarkStack* stack) { | |
8794 assert(stack->isEmpty(), "Expected precondition"); | |
8795 assert(stack->capacity() > num, "Shouldn't bite more than can chew"); | |
8796 size_t i = num; | |
8797 oop cur = _overflow_list; | |
8798 const markOop proto = markOopDesc::prototype(); | |
534 | 8799 NOT_PRODUCT(ssize_t n = 0;) |
0 | 8800 for (oop next; i > 0 && cur != NULL; cur = next, i--) { |
8801 next = oop(cur->mark()); | |
8802 cur->set_mark(proto); // until proven otherwise | |
8803 assert(cur->is_oop(), "Should be an oop"); | |
8804 bool res = stack->push(cur); | |
8805 assert(res, "Bit off more than can chew?"); | |
8806 NOT_PRODUCT(n++;) | |
8807 } | |
8808 _overflow_list = cur; | |
8809 #ifndef PRODUCT | |
8810 assert(_num_par_pushes >= n, "Too many pops?"); | |
8811 _num_par_pushes -=n; | |
8812 #endif | |
8813 return !stack->isEmpty(); | |
8814 } | |
8815 | |
534 | 8816 #define BUSY (oop(0x1aff1aff)) |
8817 // (MT-safe) Get a prefix of at most "num" from the list. | |
8818 // The overflow list is chained through the mark word of | |
8819 // each object in the list. We fetch the entire list, | |
8820 // break off a prefix of the right size and return the | |
8821 // remainder. If other threads try to take objects from | |
8822 // the overflow list at that time, they will wait for | |
8823 // some time to see if data becomes available. If (and | |
8824 // only if) another thread places one or more object(s) | |
8825 // on the global list before we have returned the suffix | |
8826 // to the global list, we will walk down our local list | |
8827 // to find its end and append the global list to | |
8828 // our suffix before returning it. This suffix walk can | |
8829 // prove to be expensive (quadratic in the amount of traffic) | |
8830 // when there are many objects in the overflow list and | |
8831 // there is much producer-consumer contention on the list. | |
8832 // *NOTE*: The overflow list manipulation code here and | |
8833 // in ParNewGeneration:: are very similar in shape, | |
8834 // except that in the ParNew case we use the old (from/eden) | |
8835 // copy of the object to thread the list via its klass word. | |
8836 // Because of the common code, if you make any changes in | |
8837 // the code below, please check the ParNew version to see if | |
8838 // similar changes might be needed. | |
8839 // CR 6797058 has been filed to consolidate the common code. | |
0 | 8840 bool CMSCollector::par_take_from_overflow_list(size_t num, |
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8841 OopTaskQueue* work_q, |
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8842 int no_of_gc_threads) { |
534 | 8843 assert(work_q->size() == 0, "First empty local work queue"); |
0 | 8844 assert(num < work_q->max_elems(), "Can't bite more than we can chew"); |
8845 if (_overflow_list == NULL) { | |
8846 return false; | |
8847 } | |
8848 // Grab the entire list; we'll put back a suffix | |
534 | 8849 oop prefix = (oop)Atomic::xchg_ptr(BUSY, &_overflow_list); |
8850 Thread* tid = Thread::current(); | |
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8851 // Before "no_of_gc_threads" was introduced CMSOverflowSpinCount was |
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8852 // set to ParallelGCThreads. |
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8853 size_t CMSOverflowSpinCount = (size_t) no_of_gc_threads; // was ParallelGCThreads; |
534 | 8854 size_t sleep_time_millis = MAX2((size_t)1, num/100); |
8855 // If the list is busy, we spin for a short while, | |
8856 // sleeping between attempts to get the list. | |
8857 for (size_t spin = 0; prefix == BUSY && spin < CMSOverflowSpinCount; spin++) { | |
8858 os::sleep(tid, sleep_time_millis, false); | |
8859 if (_overflow_list == NULL) { | |
8860 // Nothing left to take | |
8861 return false; | |
8862 } else if (_overflow_list != BUSY) { | |
8863 // Try and grab the prefix | |
8864 prefix = (oop)Atomic::xchg_ptr(BUSY, &_overflow_list); | |
8865 } | |
8866 } | |
8867 // If the list was found to be empty, or we spun long | |
8868 // enough, we give up and return empty-handed. If we leave | |
8869 // the list in the BUSY state below, it must be the case that | |
8870 // some other thread holds the overflow list and will set it | |
8871 // to a non-BUSY state in the future. | |
8872 if (prefix == NULL || prefix == BUSY) { | |
8873 // Nothing to take or waited long enough | |
8874 if (prefix == NULL) { | |
8875 // Write back the NULL in case we overwrote it with BUSY above | |
8876 // and it is still the same value. | |
8877 (void) Atomic::cmpxchg_ptr(NULL, &_overflow_list, BUSY); | |
8878 } | |
8879 return false; | |
8880 } | |
8881 assert(prefix != NULL && prefix != BUSY, "Error"); | |
0 | 8882 size_t i = num; |
8883 oop cur = prefix; | |
534 | 8884 // Walk down the first "num" objects, unless we reach the end. |
0 | 8885 for (; i > 1 && cur->mark() != NULL; cur = oop(cur->mark()), i--); |
534 | 8886 if (cur->mark() == NULL) { |
8887 // We have "num" or fewer elements in the list, so there | |
8888 // is nothing to return to the global list. | |
8889 // Write back the NULL in lieu of the BUSY we wrote | |
8890 // above, if it is still the same value. | |
8891 if (_overflow_list == BUSY) { | |
8892 (void) Atomic::cmpxchg_ptr(NULL, &_overflow_list, BUSY); | |
8893 } | |
8894 } else { | |
8895 // Chop off the suffix and rerturn it to the global list. | |
8896 assert(cur->mark() != BUSY, "Error"); | |
0 | 8897 oop suffix_head = cur->mark(); // suffix will be put back on global list |
8898 cur->set_mark(NULL); // break off suffix | |
534 | 8899 // It's possible that the list is still in the empty(busy) state |
8900 // we left it in a short while ago; in that case we may be | |
8901 // able to place back the suffix without incurring the cost | |
8902 // of a walk down the list. | |
0 | 8903 oop observed_overflow_list = _overflow_list; |
534 | 8904 oop cur_overflow_list = observed_overflow_list; |
8905 bool attached = false; | |
8906 while (observed_overflow_list == BUSY || observed_overflow_list == NULL) { | |
0 | 8907 observed_overflow_list = |
534 | 8908 (oop) Atomic::cmpxchg_ptr(suffix_head, &_overflow_list, cur_overflow_list); |
8909 if (cur_overflow_list == observed_overflow_list) { | |
8910 attached = true; | |
8911 break; | |
8912 } else cur_overflow_list = observed_overflow_list; | |
8913 } | |
8914 if (!attached) { | |
8915 // Too bad, someone else sneaked in (at least) an element; we'll need | |
8916 // to do a splice. Find tail of suffix so we can prepend suffix to global | |
8917 // list. | |
8918 for (cur = suffix_head; cur->mark() != NULL; cur = (oop)(cur->mark())); | |
8919 oop suffix_tail = cur; | |
8920 assert(suffix_tail != NULL && suffix_tail->mark() == NULL, | |
8921 "Tautology"); | |
8922 observed_overflow_list = _overflow_list; | |
8923 do { | |
8924 cur_overflow_list = observed_overflow_list; | |
8925 if (cur_overflow_list != BUSY) { | |
8926 // Do the splice ... | |
8927 suffix_tail->set_mark(markOop(cur_overflow_list)); | |
8928 } else { // cur_overflow_list == BUSY | |
8929 suffix_tail->set_mark(NULL); | |
8930 } | |
8931 // ... and try to place spliced list back on overflow_list ... | |
8932 observed_overflow_list = | |
8933 (oop) Atomic::cmpxchg_ptr(suffix_head, &_overflow_list, cur_overflow_list); | |
8934 } while (cur_overflow_list != observed_overflow_list); | |
8935 // ... until we have succeeded in doing so. | |
8936 } | |
0 | 8937 } |
8938 | |
8939 // Push the prefix elements on work_q | |
8940 assert(prefix != NULL, "control point invariant"); | |
8941 const markOop proto = markOopDesc::prototype(); | |
8942 oop next; | |
534 | 8943 NOT_PRODUCT(ssize_t n = 0;) |
0 | 8944 for (cur = prefix; cur != NULL; cur = next) { |
8945 next = oop(cur->mark()); | |
8946 cur->set_mark(proto); // until proven otherwise | |
8947 assert(cur->is_oop(), "Should be an oop"); | |
8948 bool res = work_q->push(cur); | |
8949 assert(res, "Bit off more than we can chew?"); | |
8950 NOT_PRODUCT(n++;) | |
8951 } | |
8952 #ifndef PRODUCT | |
8953 assert(_num_par_pushes >= n, "Too many pops?"); | |
8954 Atomic::add_ptr(-(intptr_t)n, &_num_par_pushes); | |
8955 #endif | |
8956 return true; | |
8957 } | |
8958 | |
8959 // Single-threaded | |
8960 void CMSCollector::push_on_overflow_list(oop p) { | |
8961 NOT_PRODUCT(_num_par_pushes++;) | |
8962 assert(p->is_oop(), "Not an oop"); | |
8963 preserve_mark_if_necessary(p); | |
8964 p->set_mark((markOop)_overflow_list); | |
8965 _overflow_list = p; | |
8966 } | |
8967 | |
8968 // Multi-threaded; use CAS to prepend to overflow list | |
8969 void CMSCollector::par_push_on_overflow_list(oop p) { | |
8970 NOT_PRODUCT(Atomic::inc_ptr(&_num_par_pushes);) | |
8971 assert(p->is_oop(), "Not an oop"); | |
8972 par_preserve_mark_if_necessary(p); | |
8973 oop observed_overflow_list = _overflow_list; | |
8974 oop cur_overflow_list; | |
8975 do { | |
8976 cur_overflow_list = observed_overflow_list; | |
534 | 8977 if (cur_overflow_list != BUSY) { |
8978 p->set_mark(markOop(cur_overflow_list)); | |
8979 } else { | |
8980 p->set_mark(NULL); | |
8981 } | |
0 | 8982 observed_overflow_list = |
8983 (oop) Atomic::cmpxchg_ptr(p, &_overflow_list, cur_overflow_list); | |
8984 } while (cur_overflow_list != observed_overflow_list); | |
8985 } | |
534 | 8986 #undef BUSY |
0 | 8987 |
8988 // Single threaded | |
8989 // General Note on GrowableArray: pushes may silently fail | |
8990 // because we are (temporarily) out of C-heap for expanding | |
8991 // the stack. The problem is quite ubiquitous and affects | |
8992 // a lot of code in the JVM. The prudent thing for GrowableArray | |
8993 // to do (for now) is to exit with an error. However, that may | |
8994 // be too draconian in some cases because the caller may be | |
534 | 8995 // able to recover without much harm. For such cases, we |
0 | 8996 // should probably introduce a "soft_push" method which returns |
8997 // an indication of success or failure with the assumption that | |
8998 // the caller may be able to recover from a failure; code in | |
8999 // the VM can then be changed, incrementally, to deal with such | |
9000 // failures where possible, thus, incrementally hardening the VM | |
9001 // in such low resource situations. | |
9002 void CMSCollector::preserve_mark_work(oop p, markOop m) { | |
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9003 _preserved_oop_stack.push(p); |
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9004 _preserved_mark_stack.push(m); |
0 | 9005 assert(m == p->mark(), "Mark word changed"); |
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9006 assert(_preserved_oop_stack.size() == _preserved_mark_stack.size(), |
0 | 9007 "bijection"); |
9008 } | |
9009 | |
9010 // Single threaded | |
9011 void CMSCollector::preserve_mark_if_necessary(oop p) { | |
9012 markOop m = p->mark(); | |
9013 if (m->must_be_preserved(p)) { | |
9014 preserve_mark_work(p, m); | |
9015 } | |
9016 } | |
9017 | |
9018 void CMSCollector::par_preserve_mark_if_necessary(oop p) { | |
9019 markOop m = p->mark(); | |
9020 if (m->must_be_preserved(p)) { | |
9021 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); | |
9022 // Even though we read the mark word without holding | |
9023 // the lock, we are assured that it will not change | |
9024 // because we "own" this oop, so no other thread can | |
9025 // be trying to push it on the overflow list; see | |
9026 // the assertion in preserve_mark_work() that checks | |
9027 // that m == p->mark(). | |
9028 preserve_mark_work(p, m); | |
9029 } | |
9030 } | |
9031 | |
9032 // We should be able to do this multi-threaded, | |
9033 // a chunk of stack being a task (this is | |
9034 // correct because each oop only ever appears | |
9035 // once in the overflow list. However, it's | |
9036 // not very easy to completely overlap this with | |
9037 // other operations, so will generally not be done | |
9038 // until all work's been completed. Because we | |
9039 // expect the preserved oop stack (set) to be small, | |
9040 // it's probably fine to do this single-threaded. | |
9041 // We can explore cleverer concurrent/overlapped/parallel | |
9042 // processing of preserved marks if we feel the | |
9043 // need for this in the future. Stack overflow should | |
9044 // be so rare in practice and, when it happens, its | |
9045 // effect on performance so great that this will | |
9046 // likely just be in the noise anyway. | |
9047 void CMSCollector::restore_preserved_marks_if_any() { | |
9048 assert(SafepointSynchronize::is_at_safepoint(), | |
9049 "world should be stopped"); | |
9050 assert(Thread::current()->is_ConcurrentGC_thread() || | |
9051 Thread::current()->is_VM_thread(), | |
9052 "should be single-threaded"); | |
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9053 assert(_preserved_oop_stack.size() == _preserved_mark_stack.size(), |
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9054 "bijection"); |
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9055 |
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9056 while (!_preserved_oop_stack.is_empty()) { |
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9057 oop p = _preserved_oop_stack.pop(); |
0 | 9058 assert(p->is_oop(), "Should be an oop"); |
9059 assert(_span.contains(p), "oop should be in _span"); | |
9060 assert(p->mark() == markOopDesc::prototype(), | |
9061 "Set when taken from overflow list"); | |
1836
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9062 markOop m = _preserved_mark_stack.pop(); |
0 | 9063 p->set_mark(m); |
9064 } | |
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9065 assert(_preserved_mark_stack.is_empty() && _preserved_oop_stack.is_empty(), |
0 | 9066 "stacks were cleared above"); |
9067 } | |
9068 | |
9069 #ifndef PRODUCT | |
9070 bool CMSCollector::no_preserved_marks() const { | |
1836
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9071 return _preserved_mark_stack.is_empty() && _preserved_oop_stack.is_empty(); |
0 | 9072 } |
9073 #endif | |
9074 | |
9075 CMSAdaptiveSizePolicy* ASConcurrentMarkSweepGeneration::cms_size_policy() const | |
9076 { | |
9077 GenCollectedHeap* gch = (GenCollectedHeap*) GenCollectedHeap::heap(); | |
9078 CMSAdaptiveSizePolicy* size_policy = | |
9079 (CMSAdaptiveSizePolicy*) gch->gen_policy()->size_policy(); | |
9080 assert(size_policy->is_gc_cms_adaptive_size_policy(), | |
9081 "Wrong type for size policy"); | |
9082 return size_policy; | |
9083 } | |
9084 | |
9085 void ASConcurrentMarkSweepGeneration::resize(size_t cur_promo_size, | |
9086 size_t desired_promo_size) { | |
9087 if (cur_promo_size < desired_promo_size) { | |
9088 size_t expand_bytes = desired_promo_size - cur_promo_size; | |
9089 if (PrintAdaptiveSizePolicy && Verbose) { | |
9090 gclog_or_tty->print_cr(" ASConcurrentMarkSweepGeneration::resize " | |
9091 "Expanding tenured generation by " SIZE_FORMAT " (bytes)", | |
9092 expand_bytes); | |
9093 } | |
9094 expand(expand_bytes, | |
9095 MinHeapDeltaBytes, | |
9096 CMSExpansionCause::_adaptive_size_policy); | |
9097 } else if (desired_promo_size < cur_promo_size) { | |
9098 size_t shrink_bytes = cur_promo_size - desired_promo_size; | |
9099 if (PrintAdaptiveSizePolicy && Verbose) { | |
9100 gclog_or_tty->print_cr(" ASConcurrentMarkSweepGeneration::resize " | |
9101 "Shrinking tenured generation by " SIZE_FORMAT " (bytes)", | |
9102 shrink_bytes); | |
9103 } | |
9104 shrink(shrink_bytes); | |
9105 } | |
9106 } | |
9107 | |
9108 CMSGCAdaptivePolicyCounters* ASConcurrentMarkSweepGeneration::gc_adaptive_policy_counters() { | |
9109 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
9110 CMSGCAdaptivePolicyCounters* counters = | |
9111 (CMSGCAdaptivePolicyCounters*) gch->collector_policy()->counters(); | |
9112 assert(counters->kind() == GCPolicyCounters::CMSGCAdaptivePolicyCountersKind, | |
9113 "Wrong kind of counters"); | |
9114 return counters; | |
9115 } | |
9116 | |
9117 | |
9118 void ASConcurrentMarkSweepGeneration::update_counters() { | |
9119 if (UsePerfData) { | |
9120 _space_counters->update_all(); | |
9121 _gen_counters->update_all(); | |
9122 CMSGCAdaptivePolicyCounters* counters = gc_adaptive_policy_counters(); | |
9123 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
9124 CMSGCStats* gc_stats_l = (CMSGCStats*) gc_stats(); | |
9125 assert(gc_stats_l->kind() == GCStats::CMSGCStatsKind, | |
9126 "Wrong gc statistics type"); | |
9127 counters->update_counters(gc_stats_l); | |
9128 } | |
9129 } | |
9130 | |
9131 void ASConcurrentMarkSweepGeneration::update_counters(size_t used) { | |
9132 if (UsePerfData) { | |
9133 _space_counters->update_used(used); | |
9134 _space_counters->update_capacity(); | |
9135 _gen_counters->update_all(); | |
9136 | |
9137 CMSGCAdaptivePolicyCounters* counters = gc_adaptive_policy_counters(); | |
9138 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
9139 CMSGCStats* gc_stats_l = (CMSGCStats*) gc_stats(); | |
9140 assert(gc_stats_l->kind() == GCStats::CMSGCStatsKind, | |
9141 "Wrong gc statistics type"); | |
9142 counters->update_counters(gc_stats_l); | |
9143 } | |
9144 } | |
9145 | |
9146 void ASConcurrentMarkSweepGeneration::shrink_by(size_t desired_bytes) { | |
9147 assert_locked_or_safepoint(Heap_lock); | |
9148 assert_lock_strong(freelistLock()); | |
9149 HeapWord* old_end = _cmsSpace->end(); | |
9150 HeapWord* unallocated_start = _cmsSpace->unallocated_block(); | |
9151 assert(old_end >= unallocated_start, "Miscalculation of unallocated_start"); | |
9152 FreeChunk* chunk_at_end = find_chunk_at_end(); | |
9153 if (chunk_at_end == NULL) { | |
9154 // No room to shrink | |
9155 if (PrintGCDetails && Verbose) { | |
9156 gclog_or_tty->print_cr("No room to shrink: old_end " | |
9157 PTR_FORMAT " unallocated_start " PTR_FORMAT | |
9158 " chunk_at_end " PTR_FORMAT, | |
9159 old_end, unallocated_start, chunk_at_end); | |
9160 } | |
9161 return; | |
9162 } else { | |
9163 | |
9164 // Find the chunk at the end of the space and determine | |
9165 // how much it can be shrunk. | |
9166 size_t shrinkable_size_in_bytes = chunk_at_end->size(); | |
9167 size_t aligned_shrinkable_size_in_bytes = | |
9168 align_size_down(shrinkable_size_in_bytes, os::vm_page_size()); | |
6885 | 9169 assert(unallocated_start <= (HeapWord*) chunk_at_end->end(), |
0 | 9170 "Inconsistent chunk at end of space"); |
9171 size_t bytes = MIN2(desired_bytes, aligned_shrinkable_size_in_bytes); | |
9172 size_t word_size_before = heap_word_size(_virtual_space.committed_size()); | |
9173 | |
9174 // Shrink the underlying space | |
9175 _virtual_space.shrink_by(bytes); | |
9176 if (PrintGCDetails && Verbose) { | |
9177 gclog_or_tty->print_cr("ConcurrentMarkSweepGeneration::shrink_by:" | |
9178 " desired_bytes " SIZE_FORMAT | |
9179 " shrinkable_size_in_bytes " SIZE_FORMAT | |
9180 " aligned_shrinkable_size_in_bytes " SIZE_FORMAT | |
9181 " bytes " SIZE_FORMAT, | |
9182 desired_bytes, shrinkable_size_in_bytes, | |
9183 aligned_shrinkable_size_in_bytes, bytes); | |
9184 gclog_or_tty->print_cr(" old_end " SIZE_FORMAT | |
9185 " unallocated_start " SIZE_FORMAT, | |
9186 old_end, unallocated_start); | |
9187 } | |
9188 | |
9189 // If the space did shrink (shrinking is not guaranteed), | |
9190 // shrink the chunk at the end by the appropriate amount. | |
9191 if (((HeapWord*)_virtual_space.high()) < old_end) { | |
9192 size_t new_word_size = | |
9193 heap_word_size(_virtual_space.committed_size()); | |
9194 | |
9195 // Have to remove the chunk from the dictionary because it is changing | |
9196 // size and might be someplace elsewhere in the dictionary. | |
9197 | |
9198 // Get the chunk at end, shrink it, and put it | |
9199 // back. | |
9200 _cmsSpace->removeChunkFromDictionary(chunk_at_end); | |
9201 size_t word_size_change = word_size_before - new_word_size; | |
9202 size_t chunk_at_end_old_size = chunk_at_end->size(); | |
9203 assert(chunk_at_end_old_size >= word_size_change, | |
9204 "Shrink is too large"); | |
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9205 chunk_at_end->set_size(chunk_at_end_old_size - |
0 | 9206 word_size_change); |
9207 _cmsSpace->freed((HeapWord*) chunk_at_end->end(), | |
9208 word_size_change); | |
9209 | |
9210 _cmsSpace->returnChunkToDictionary(chunk_at_end); | |
9211 | |
9212 MemRegion mr(_cmsSpace->bottom(), new_word_size); | |
9213 _bts->resize(new_word_size); // resize the block offset shared array | |
9214 Universe::heap()->barrier_set()->resize_covered_region(mr); | |
9215 _cmsSpace->assert_locked(); | |
9216 _cmsSpace->set_end((HeapWord*)_virtual_space.high()); | |
9217 | |
9218 NOT_PRODUCT(_cmsSpace->dictionary()->verify()); | |
9219 | |
9220 // update the space and generation capacity counters | |
9221 if (UsePerfData) { | |
9222 _space_counters->update_capacity(); | |
9223 _gen_counters->update_all(); | |
9224 } | |
9225 | |
9226 if (Verbose && PrintGCDetails) { | |
9227 size_t new_mem_size = _virtual_space.committed_size(); | |
9228 size_t old_mem_size = new_mem_size + bytes; | |
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9229 gclog_or_tty->print_cr("Shrinking %s from " SIZE_FORMAT "K by " SIZE_FORMAT "K to " SIZE_FORMAT "K", |
0 | 9230 name(), old_mem_size/K, bytes/K, new_mem_size/K); |
9231 } | |
9232 } | |
9233 | |
9234 assert(_cmsSpace->unallocated_block() <= _cmsSpace->end(), | |
9235 "Inconsistency at end of space"); | |
6885 | 9236 assert(chunk_at_end->end() == (uintptr_t*) _cmsSpace->end(), |
0 | 9237 "Shrinking is inconsistent"); |
9238 return; | |
9239 } | |
9240 } | |
9241 | |
9242 // Transfer some number of overflown objects to usual marking | |
9243 // stack. Return true if some objects were transferred. | |
9244 bool MarkRefsIntoAndScanClosure::take_from_overflow_list() { | |
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9245 size_t num = MIN2((size_t)(_mark_stack->capacity() - _mark_stack->length())/4, |
0 | 9246 (size_t)ParGCDesiredObjsFromOverflowList); |
9247 | |
9248 bool res = _collector->take_from_overflow_list(num, _mark_stack); | |
9249 assert(_collector->overflow_list_is_empty() || res, | |
9250 "If list is not empty, we should have taken something"); | |
9251 assert(!res || !_mark_stack->isEmpty(), | |
9252 "If we took something, it should now be on our stack"); | |
9253 return res; | |
9254 } | |
9255 | |
9256 size_t MarkDeadObjectsClosure::do_blk(HeapWord* addr) { | |
9257 size_t res = _sp->block_size_no_stall(addr, _collector); | |
9258 if (_sp->block_is_obj(addr)) { | |
9259 if (_live_bit_map->isMarked(addr)) { | |
9260 // It can't have been dead in a previous cycle | |
9261 guarantee(!_dead_bit_map->isMarked(addr), "No resurrection!"); | |
9262 } else { | |
9263 _dead_bit_map->mark(addr); // mark the dead object | |
9264 } | |
9265 } | |
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9266 // Could be 0, if the block size could not be computed without stalling. |
0 | 9267 return res; |
9268 } | |
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9269 |
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9270 TraceCMSMemoryManagerStats::TraceCMSMemoryManagerStats(CMSCollector::CollectorState phase, GCCause::Cause cause): TraceMemoryManagerStats() { |
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9271 |
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9272 switch (phase) { |
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9273 case CMSCollector::InitialMarking: |
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9274 initialize(true /* fullGC */ , |
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9275 cause /* cause of the GC */, |
1703
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9276 true /* recordGCBeginTime */, |
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9277 true /* recordPreGCUsage */, |
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9278 false /* recordPeakUsage */, |
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9279 false /* recordPostGCusage */, |
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9280 true /* recordAccumulatedGCTime */, |
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9281 false /* recordGCEndTime */, |
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9282 false /* countCollection */ ); |
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1579
diff
changeset
|
9283 break; |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9284 |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9285 case CMSCollector::FinalMarking: |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9286 initialize(true /* fullGC */ , |
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
parents:
3293
diff
changeset
|
9287 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
|
9288 false /* recordGCBeginTime */, |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9289 false /* recordPreGCUsage */, |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9290 false /* recordPeakUsage */, |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9291 false /* recordPostGCusage */, |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9292 true /* recordAccumulatedGCTime */, |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9293 false /* recordGCEndTime */, |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9294 false /* countCollection */ ); |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9295 break; |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9296 |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9297 case CMSCollector::Sweeping: |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9298 initialize(true /* fullGC */ , |
3356
78542e2b5e35
7036199: Adding a notification to the implementation of GarbageCollectorMXBeans
fparain
parents:
3293
diff
changeset
|
9299 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
|
9300 false /* recordGCBeginTime */, |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9301 false /* recordPreGCUsage */, |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9302 true /* recordPeakUsage */, |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9303 true /* recordPostGCusage */, |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9304 false /* recordAccumulatedGCTime */, |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9305 true /* recordGCEndTime */, |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9306 true /* countCollection */ ); |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9307 break; |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9308 |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9309 default: |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9310 ShouldNotReachHere(); |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9311 } |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9312 } |
f6f3eef8a521
6581734: CMS Old Gen's collection usage is zero after GC which is incorrect
kevinw
parents:
1579
diff
changeset
|
9313 |