Mercurial > hg > truffle
annotate src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp @ 1562:dfe27f03244a
Merge
author | trims |
---|---|
date | Tue, 01 Jun 2010 11:48:33 -0700 |
parents | c18cbe5936b8 |
children | e9ff18c4ace7 |
rev | line source |
---|---|
0 | 1 /* |
1552
c18cbe5936b8
6941466: Oracle rebranding changes for Hotspot repositories
trims
parents:
1521
diff
changeset
|
2 * Copyright (c) 2001, 2010, 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 * | |
1552
c18cbe5936b8
6941466: Oracle rebranding changes for Hotspot repositories
trims
parents:
1521
diff
changeset
|
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
c18cbe5936b8
6941466: Oracle rebranding changes for Hotspot repositories
trims
parents:
1521
diff
changeset
|
20 * or visit www.oracle.com if you need additional information or have any |
c18cbe5936b8
6941466: Oracle rebranding changes for Hotspot repositories
trims
parents:
1521
diff
changeset
|
21 * questions. |
0 | 22 * |
23 */ | |
24 | |
25 # include "incls/_precompiled.incl" | |
26 # include "incls/_concurrentMarkSweepGeneration.cpp.incl" | |
27 | |
28 // statics | |
29 CMSCollector* ConcurrentMarkSweepGeneration::_collector = NULL; | |
30 bool CMSCollector::_full_gc_requested = false; | |
31 | |
32 ////////////////////////////////////////////////////////////////// | |
33 // In support of CMS/VM thread synchronization | |
34 ////////////////////////////////////////////////////////////////// | |
35 // We split use of the CGC_lock into 2 "levels". | |
36 // The low-level locking is of the usual CGC_lock monitor. We introduce | |
37 // a higher level "token" (hereafter "CMS token") built on top of the | |
38 // low level monitor (hereafter "CGC lock"). | |
39 // The token-passing protocol gives priority to the VM thread. The | |
40 // CMS-lock doesn't provide any fairness guarantees, but clients | |
41 // should ensure that it is only held for very short, bounded | |
42 // durations. | |
43 // | |
44 // When either of the CMS thread or the VM thread is involved in | |
45 // collection operations during which it does not want the other | |
46 // thread to interfere, it obtains the CMS token. | |
47 // | |
48 // If either thread tries to get the token while the other has | |
49 // it, that thread waits. However, if the VM thread and CMS thread | |
50 // both want the token, then the VM thread gets priority while the | |
51 // CMS thread waits. This ensures, for instance, that the "concurrent" | |
52 // phases of the CMS thread's work do not block out the VM thread | |
53 // for long periods of time as the CMS thread continues to hog | |
54 // the token. (See bug 4616232). | |
55 // | |
56 // The baton-passing functions are, however, controlled by the | |
57 // flags _foregroundGCShouldWait and _foregroundGCIsActive, | |
58 // and here the low-level CMS lock, not the high level token, | |
59 // ensures mutual exclusion. | |
60 // | |
61 // Two important conditions that we have to satisfy: | |
62 // 1. if a thread does a low-level wait on the CMS lock, then it | |
63 // relinquishes the CMS token if it were holding that token | |
64 // when it acquired the low-level CMS lock. | |
65 // 2. any low-level notifications on the low-level lock | |
66 // should only be sent when a thread has relinquished the token. | |
67 // | |
68 // In the absence of either property, we'd have potential deadlock. | |
69 // | |
70 // We protect each of the CMS (concurrent and sequential) phases | |
71 // with the CMS _token_, not the CMS _lock_. | |
72 // | |
73 // The only code protected by CMS lock is the token acquisition code | |
74 // itself, see ConcurrentMarkSweepThread::[de]synchronize(), and the | |
75 // baton-passing code. | |
76 // | |
77 // Unfortunately, i couldn't come up with a good abstraction to factor and | |
78 // hide the naked CGC_lock manipulation in the baton-passing code | |
79 // further below. That's something we should try to do. Also, the proof | |
80 // of correctness of this 2-level locking scheme is far from obvious, | |
81 // and potentially quite slippery. We have an uneasy supsicion, for instance, | |
82 // that there may be a theoretical possibility of delay/starvation in the | |
83 // low-level lock/wait/notify scheme used for the baton-passing because of | |
84 // potential intereference with the priority scheme embodied in the | |
85 // CMS-token-passing protocol. See related comments at a CGC_lock->wait() | |
86 // invocation further below and marked with "XXX 20011219YSR". | |
87 // Indeed, as we note elsewhere, this may become yet more slippery | |
88 // in the presence of multiple CMS and/or multiple VM threads. XXX | |
89 | |
90 class CMSTokenSync: public StackObj { | |
91 private: | |
92 bool _is_cms_thread; | |
93 public: | |
94 CMSTokenSync(bool is_cms_thread): | |
95 _is_cms_thread(is_cms_thread) { | |
96 assert(is_cms_thread == Thread::current()->is_ConcurrentGC_thread(), | |
97 "Incorrect argument to constructor"); | |
98 ConcurrentMarkSweepThread::synchronize(_is_cms_thread); | |
99 } | |
100 | |
101 ~CMSTokenSync() { | |
102 assert(_is_cms_thread ? | |
103 ConcurrentMarkSweepThread::cms_thread_has_cms_token() : | |
104 ConcurrentMarkSweepThread::vm_thread_has_cms_token(), | |
105 "Incorrect state"); | |
106 ConcurrentMarkSweepThread::desynchronize(_is_cms_thread); | |
107 } | |
108 }; | |
109 | |
110 // Convenience class that does a CMSTokenSync, and then acquires | |
111 // upto three locks. | |
112 class CMSTokenSyncWithLocks: public CMSTokenSync { | |
113 private: | |
114 // Note: locks are acquired in textual declaration order | |
115 // and released in the opposite order | |
116 MutexLockerEx _locker1, _locker2, _locker3; | |
117 public: | |
118 CMSTokenSyncWithLocks(bool is_cms_thread, Mutex* mutex1, | |
119 Mutex* mutex2 = NULL, Mutex* mutex3 = NULL): | |
120 CMSTokenSync(is_cms_thread), | |
121 _locker1(mutex1, Mutex::_no_safepoint_check_flag), | |
122 _locker2(mutex2, Mutex::_no_safepoint_check_flag), | |
123 _locker3(mutex3, Mutex::_no_safepoint_check_flag) | |
124 { } | |
125 }; | |
126 | |
127 | |
128 // Wrapper class to temporarily disable icms during a foreground cms collection. | |
129 class ICMSDisabler: public StackObj { | |
130 public: | |
131 // The ctor disables icms and wakes up the thread so it notices the change; | |
132 // the dtor re-enables icms. Note that the CMSCollector methods will check | |
133 // CMSIncrementalMode. | |
134 ICMSDisabler() { CMSCollector::disable_icms(); CMSCollector::start_icms(); } | |
135 ~ICMSDisabler() { CMSCollector::enable_icms(); } | |
136 }; | |
137 | |
138 ////////////////////////////////////////////////////////////////// | |
139 // Concurrent Mark-Sweep Generation ///////////////////////////// | |
140 ////////////////////////////////////////////////////////////////// | |
141 | |
142 NOT_PRODUCT(CompactibleFreeListSpace* debug_cms_space;) | |
143 | |
144 // This struct contains per-thread things necessary to support parallel | |
145 // young-gen collection. | |
146 class CMSParGCThreadState: public CHeapObj { | |
147 public: | |
148 CFLS_LAB lab; | |
149 PromotionInfo promo; | |
150 | |
151 // Constructor. | |
152 CMSParGCThreadState(CompactibleFreeListSpace* cfls) : lab(cfls) { | |
153 promo.setSpace(cfls); | |
154 } | |
155 }; | |
156 | |
157 ConcurrentMarkSweepGeneration::ConcurrentMarkSweepGeneration( | |
158 ReservedSpace rs, size_t initial_byte_size, int level, | |
159 CardTableRS* ct, bool use_adaptive_freelists, | |
160 FreeBlockDictionary::DictionaryChoice dictionaryChoice) : | |
161 CardGeneration(rs, initial_byte_size, level, ct), | |
162 _dilatation_factor(((double)MinChunkSize)/((double)(oopDesc::header_size()))), | |
163 _debug_collection_type(Concurrent_collection_type) | |
164 { | |
165 HeapWord* bottom = (HeapWord*) _virtual_space.low(); | |
166 HeapWord* end = (HeapWord*) _virtual_space.high(); | |
167 | |
168 _direct_allocated_words = 0; | |
169 NOT_PRODUCT( | |
170 _numObjectsPromoted = 0; | |
171 _numWordsPromoted = 0; | |
172 _numObjectsAllocated = 0; | |
173 _numWordsAllocated = 0; | |
174 ) | |
175 | |
176 _cmsSpace = new CompactibleFreeListSpace(_bts, MemRegion(bottom, end), | |
177 use_adaptive_freelists, | |
178 dictionaryChoice); | |
179 NOT_PRODUCT(debug_cms_space = _cmsSpace;) | |
180 if (_cmsSpace == NULL) { | |
181 vm_exit_during_initialization( | |
182 "CompactibleFreeListSpace allocation failure"); | |
183 } | |
184 _cmsSpace->_gen = this; | |
185 | |
186 _gc_stats = new CMSGCStats(); | |
187 | |
188 // Verify the assumption that FreeChunk::_prev and OopDesc::_klass | |
189 // offsets match. The ability to tell free chunks from objects | |
190 // depends on this property. | |
191 debug_only( | |
192 FreeChunk* junk = NULL; | |
187 | 193 assert(UseCompressedOops || |
194 junk->prev_addr() == (void*)(oop(junk)->klass_addr()), | |
0 | 195 "Offset of FreeChunk::_prev within FreeChunk must match" |
196 " that of OopDesc::_klass within OopDesc"); | |
197 ) | |
198 if (ParallelGCThreads > 0) { | |
199 typedef CMSParGCThreadState* CMSParGCThreadStatePtr; | |
200 _par_gc_thread_states = | |
201 NEW_C_HEAP_ARRAY(CMSParGCThreadStatePtr, ParallelGCThreads); | |
202 if (_par_gc_thread_states == NULL) { | |
203 vm_exit_during_initialization("Could not allocate par gc structs"); | |
204 } | |
205 for (uint i = 0; i < ParallelGCThreads; i++) { | |
206 _par_gc_thread_states[i] = new CMSParGCThreadState(cmsSpace()); | |
207 if (_par_gc_thread_states[i] == NULL) { | |
208 vm_exit_during_initialization("Could not allocate par gc structs"); | |
209 } | |
210 } | |
211 } else { | |
212 _par_gc_thread_states = NULL; | |
213 } | |
214 _incremental_collection_failed = false; | |
215 // The "dilatation_factor" is the expansion that can occur on | |
216 // account of the fact that the minimum object size in the CMS | |
217 // generation may be larger than that in, say, a contiguous young | |
218 // generation. | |
219 // Ideally, in the calculation below, we'd compute the dilatation | |
220 // factor as: MinChunkSize/(promoting_gen's min object size) | |
221 // Since we do not have such a general query interface for the | |
222 // promoting generation, we'll instead just use the mimimum | |
223 // object size (which today is a header's worth of space); | |
224 // note that all arithmetic is in units of HeapWords. | |
225 assert(MinChunkSize >= oopDesc::header_size(), "just checking"); | |
226 assert(_dilatation_factor >= 1.0, "from previous assert"); | |
227 } | |
228 | |
94
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
229 |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
230 // The field "_initiating_occupancy" represents the occupancy percentage |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
231 // at which we trigger a new collection cycle. Unless explicitly specified |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
232 // via CMSInitiating[Perm]OccupancyFraction (argument "io" below), it |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
233 // is calculated by: |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
234 // |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
235 // Let "f" be MinHeapFreeRatio in |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
236 // |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
237 // _intiating_occupancy = 100-f + |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
238 // f * (CMSTrigger[Perm]Ratio/100) |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
239 // where CMSTrigger[Perm]Ratio is the argument "tr" below. |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
240 // |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
241 // That is, if we assume the heap is at its desired maximum occupancy at the |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
242 // end of a collection, we let CMSTrigger[Perm]Ratio of the (purported) free |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
243 // space be allocated before initiating a new collection cycle. |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
244 // |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
245 void ConcurrentMarkSweepGeneration::init_initiating_occupancy(intx io, intx tr) { |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
246 assert(io <= 100 && tr >= 0 && tr <= 100, "Check the arguments"); |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
247 if (io >= 0) { |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
248 _initiating_occupancy = (double)io / 100.0; |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
249 } else { |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
250 _initiating_occupancy = ((100 - MinHeapFreeRatio) + |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
251 (double)(tr * MinHeapFreeRatio) / 100.0) |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
252 / 100.0; |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
253 } |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
254 } |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
255 |
0 | 256 void ConcurrentMarkSweepGeneration::ref_processor_init() { |
257 assert(collector() != NULL, "no collector"); | |
258 collector()->ref_processor_init(); | |
259 } | |
260 | |
261 void CMSCollector::ref_processor_init() { | |
262 if (_ref_processor == NULL) { | |
263 // Allocate and initialize a reference processor | |
264 _ref_processor = ReferenceProcessor::create_ref_processor( | |
265 _span, // span | |
266 _cmsGen->refs_discovery_is_atomic(), // atomic_discovery | |
267 _cmsGen->refs_discovery_is_mt(), // mt_discovery | |
268 &_is_alive_closure, | |
269 ParallelGCThreads, | |
270 ParallelRefProcEnabled); | |
271 // Initialize the _ref_processor field of CMSGen | |
272 _cmsGen->set_ref_processor(_ref_processor); | |
273 | |
274 // Allocate a dummy ref processor for perm gen. | |
275 ReferenceProcessor* rp2 = new ReferenceProcessor(); | |
276 if (rp2 == NULL) { | |
277 vm_exit_during_initialization("Could not allocate ReferenceProcessor object"); | |
278 } | |
279 _permGen->set_ref_processor(rp2); | |
280 } | |
281 } | |
282 | |
283 CMSAdaptiveSizePolicy* CMSCollector::size_policy() { | |
284 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
285 assert(gch->kind() == CollectedHeap::GenCollectedHeap, | |
286 "Wrong type of heap"); | |
287 CMSAdaptiveSizePolicy* sp = (CMSAdaptiveSizePolicy*) | |
288 gch->gen_policy()->size_policy(); | |
289 assert(sp->is_gc_cms_adaptive_size_policy(), | |
290 "Wrong type of size policy"); | |
291 return sp; | |
292 } | |
293 | |
294 CMSGCAdaptivePolicyCounters* CMSCollector::gc_adaptive_policy_counters() { | |
295 CMSGCAdaptivePolicyCounters* results = | |
296 (CMSGCAdaptivePolicyCounters*) collector_policy()->counters(); | |
297 assert( | |
298 results->kind() == GCPolicyCounters::CMSGCAdaptivePolicyCountersKind, | |
299 "Wrong gc policy counter kind"); | |
300 return results; | |
301 } | |
302 | |
303 | |
304 void ConcurrentMarkSweepGeneration::initialize_performance_counters() { | |
305 | |
306 const char* gen_name = "old"; | |
307 | |
308 // Generation Counters - generation 1, 1 subspace | |
309 _gen_counters = new GenerationCounters(gen_name, 1, 1, &_virtual_space); | |
310 | |
311 _space_counters = new GSpaceCounters(gen_name, 0, | |
312 _virtual_space.reserved_size(), | |
313 this, _gen_counters); | |
314 } | |
315 | |
316 CMSStats::CMSStats(ConcurrentMarkSweepGeneration* cms_gen, unsigned int alpha): | |
317 _cms_gen(cms_gen) | |
318 { | |
319 assert(alpha <= 100, "bad value"); | |
320 _saved_alpha = alpha; | |
321 | |
322 // Initialize the alphas to the bootstrap value of 100. | |
323 _gc0_alpha = _cms_alpha = 100; | |
324 | |
325 _cms_begin_time.update(); | |
326 _cms_end_time.update(); | |
327 | |
328 _gc0_duration = 0.0; | |
329 _gc0_period = 0.0; | |
330 _gc0_promoted = 0; | |
331 | |
332 _cms_duration = 0.0; | |
333 _cms_period = 0.0; | |
334 _cms_allocated = 0; | |
335 | |
336 _cms_used_at_gc0_begin = 0; | |
337 _cms_used_at_gc0_end = 0; | |
338 _allow_duty_cycle_reduction = false; | |
339 _valid_bits = 0; | |
340 _icms_duty_cycle = CMSIncrementalDutyCycle; | |
341 } | |
342 | |
1145
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
343 double CMSStats::cms_free_adjustment_factor(size_t free) const { |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
344 // TBD: CR 6909490 |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
345 return 1.0; |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
346 } |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
347 |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
348 void CMSStats::adjust_cms_free_adjustment_factor(bool fail, size_t free) { |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
349 } |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
350 |
0 | 351 // If promotion failure handling is on use |
352 // the padded average size of the promotion for each | |
353 // young generation collection. | |
354 double CMSStats::time_until_cms_gen_full() const { | |
355 size_t cms_free = _cms_gen->cmsSpace()->free(); | |
356 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
357 size_t expected_promotion = gch->get_gen(0)->capacity(); | |
358 if (HandlePromotionFailure) { | |
359 expected_promotion = MIN2( | |
360 (size_t) _cms_gen->gc_stats()->avg_promoted()->padded_average(), | |
361 expected_promotion); | |
362 } | |
363 if (cms_free > expected_promotion) { | |
364 // Start a cms collection if there isn't enough space to promote | |
365 // for the next minor collection. Use the padded average as | |
366 // a safety factor. | |
367 cms_free -= expected_promotion; | |
368 | |
369 // Adjust by the safety factor. | |
370 double cms_free_dbl = (double)cms_free; | |
1145
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
371 double cms_adjustment = (100.0 - CMSIncrementalSafetyFactor)/100.0; |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
372 // Apply a further correction factor which tries to adjust |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
373 // for recent occurance of concurrent mode failures. |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
374 cms_adjustment = cms_adjustment * cms_free_adjustment_factor(cms_free); |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
375 cms_free_dbl = cms_free_dbl * cms_adjustment; |
0 | 376 |
377 if (PrintGCDetails && Verbose) { | |
378 gclog_or_tty->print_cr("CMSStats::time_until_cms_gen_full: cms_free " | |
379 SIZE_FORMAT " expected_promotion " SIZE_FORMAT, | |
380 cms_free, expected_promotion); | |
381 gclog_or_tty->print_cr(" cms_free_dbl %f cms_consumption_rate %f", | |
382 cms_free_dbl, cms_consumption_rate() + 1.0); | |
383 } | |
384 // Add 1 in case the consumption rate goes to zero. | |
385 return cms_free_dbl / (cms_consumption_rate() + 1.0); | |
386 } | |
387 return 0.0; | |
388 } | |
389 | |
390 // Compare the duration of the cms collection to the | |
391 // time remaining before the cms generation is empty. | |
392 // Note that the time from the start of the cms collection | |
393 // to the start of the cms sweep (less than the total | |
394 // duration of the cms collection) can be used. This | |
395 // has been tried and some applications experienced | |
396 // promotion failures early in execution. This was | |
397 // possibly because the averages were not accurate | |
398 // enough at the beginning. | |
399 double CMSStats::time_until_cms_start() const { | |
400 // We add "gc0_period" to the "work" calculation | |
401 // below because this query is done (mostly) at the | |
402 // end of a scavenge, so we need to conservatively | |
403 // account for that much possible delay | |
404 // in the query so as to avoid concurrent mode failures | |
405 // due to starting the collection just a wee bit too | |
406 // late. | |
407 double work = cms_duration() + gc0_period(); | |
408 double deadline = time_until_cms_gen_full(); | |
1145
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
409 // If a concurrent mode failure occurred recently, we want to be |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
410 // more conservative and halve our expected time_until_cms_gen_full() |
0 | 411 if (work > deadline) { |
412 if (Verbose && PrintGCDetails) { | |
413 gclog_or_tty->print( | |
414 " CMSCollector: collect because of anticipated promotion " | |
415 "before full %3.7f + %3.7f > %3.7f ", cms_duration(), | |
416 gc0_period(), time_until_cms_gen_full()); | |
417 } | |
418 return 0.0; | |
419 } | |
420 return work - deadline; | |
421 } | |
422 | |
423 // Return a duty cycle based on old_duty_cycle and new_duty_cycle, limiting the | |
424 // amount of change to prevent wild oscillation. | |
425 unsigned int CMSStats::icms_damped_duty_cycle(unsigned int old_duty_cycle, | |
426 unsigned int new_duty_cycle) { | |
427 assert(old_duty_cycle <= 100, "bad input value"); | |
428 assert(new_duty_cycle <= 100, "bad input value"); | |
429 | |
430 // Note: use subtraction with caution since it may underflow (values are | |
431 // unsigned). Addition is safe since we're in the range 0-100. | |
432 unsigned int damped_duty_cycle = new_duty_cycle; | |
433 if (new_duty_cycle < old_duty_cycle) { | |
434 const unsigned int largest_delta = MAX2(old_duty_cycle / 4, 5U); | |
435 if (new_duty_cycle + largest_delta < old_duty_cycle) { | |
436 damped_duty_cycle = old_duty_cycle - largest_delta; | |
437 } | |
438 } else if (new_duty_cycle > old_duty_cycle) { | |
439 const unsigned int largest_delta = MAX2(old_duty_cycle / 4, 15U); | |
440 if (new_duty_cycle > old_duty_cycle + largest_delta) { | |
441 damped_duty_cycle = MIN2(old_duty_cycle + largest_delta, 100U); | |
442 } | |
443 } | |
444 assert(damped_duty_cycle <= 100, "invalid duty cycle computed"); | |
445 | |
446 if (CMSTraceIncrementalPacing) { | |
447 gclog_or_tty->print(" [icms_damped_duty_cycle(%d,%d) = %d] ", | |
448 old_duty_cycle, new_duty_cycle, damped_duty_cycle); | |
449 } | |
450 return damped_duty_cycle; | |
451 } | |
452 | |
453 unsigned int CMSStats::icms_update_duty_cycle_impl() { | |
454 assert(CMSIncrementalPacing && valid(), | |
455 "should be handled in icms_update_duty_cycle()"); | |
456 | |
457 double cms_time_so_far = cms_timer().seconds(); | |
458 double scaled_duration = cms_duration_per_mb() * _cms_used_at_gc0_end / M; | |
459 double scaled_duration_remaining = fabsd(scaled_duration - cms_time_so_far); | |
460 | |
461 // Avoid division by 0. | |
462 double time_until_full = MAX2(time_until_cms_gen_full(), 0.01); | |
463 double duty_cycle_dbl = 100.0 * scaled_duration_remaining / time_until_full; | |
464 | |
465 unsigned int new_duty_cycle = MIN2((unsigned int)duty_cycle_dbl, 100U); | |
466 if (new_duty_cycle > _icms_duty_cycle) { | |
467 // Avoid very small duty cycles (1 or 2); 0 is allowed. | |
468 if (new_duty_cycle > 2) { | |
469 _icms_duty_cycle = icms_damped_duty_cycle(_icms_duty_cycle, | |
470 new_duty_cycle); | |
471 } | |
472 } else if (_allow_duty_cycle_reduction) { | |
473 // The duty cycle is reduced only once per cms cycle (see record_cms_end()). | |
474 new_duty_cycle = icms_damped_duty_cycle(_icms_duty_cycle, new_duty_cycle); | |
475 // Respect the minimum duty cycle. | |
476 unsigned int min_duty_cycle = (unsigned int)CMSIncrementalDutyCycleMin; | |
477 _icms_duty_cycle = MAX2(new_duty_cycle, min_duty_cycle); | |
478 } | |
479 | |
480 if (PrintGCDetails || CMSTraceIncrementalPacing) { | |
481 gclog_or_tty->print(" icms_dc=%d ", _icms_duty_cycle); | |
482 } | |
483 | |
484 _allow_duty_cycle_reduction = false; | |
485 return _icms_duty_cycle; | |
486 } | |
487 | |
488 #ifndef PRODUCT | |
489 void CMSStats::print_on(outputStream *st) const { | |
490 st->print(" gc0_alpha=%d,cms_alpha=%d", _gc0_alpha, _cms_alpha); | |
491 st->print(",gc0_dur=%g,gc0_per=%g,gc0_promo=" SIZE_FORMAT, | |
492 gc0_duration(), gc0_period(), gc0_promoted()); | |
493 st->print(",cms_dur=%g,cms_dur_per_mb=%g,cms_per=%g,cms_alloc=" SIZE_FORMAT, | |
494 cms_duration(), cms_duration_per_mb(), | |
495 cms_period(), cms_allocated()); | |
496 st->print(",cms_since_beg=%g,cms_since_end=%g", | |
497 cms_time_since_begin(), cms_time_since_end()); | |
498 st->print(",cms_used_beg=" SIZE_FORMAT ",cms_used_end=" SIZE_FORMAT, | |
499 _cms_used_at_gc0_begin, _cms_used_at_gc0_end); | |
500 if (CMSIncrementalMode) { | |
501 st->print(",dc=%d", icms_duty_cycle()); | |
502 } | |
503 | |
504 if (valid()) { | |
505 st->print(",promo_rate=%g,cms_alloc_rate=%g", | |
506 promotion_rate(), cms_allocation_rate()); | |
507 st->print(",cms_consumption_rate=%g,time_until_full=%g", | |
508 cms_consumption_rate(), time_until_cms_gen_full()); | |
509 } | |
510 st->print(" "); | |
511 } | |
512 #endif // #ifndef PRODUCT | |
513 | |
514 CMSCollector::CollectorState CMSCollector::_collectorState = | |
515 CMSCollector::Idling; | |
516 bool CMSCollector::_foregroundGCIsActive = false; | |
517 bool CMSCollector::_foregroundGCShouldWait = false; | |
518 | |
519 CMSCollector::CMSCollector(ConcurrentMarkSweepGeneration* cmsGen, | |
520 ConcurrentMarkSweepGeneration* permGen, | |
521 CardTableRS* ct, | |
522 ConcurrentMarkSweepPolicy* cp): | |
523 _cmsGen(cmsGen), | |
524 _permGen(permGen), | |
525 _ct(ct), | |
526 _ref_processor(NULL), // will be set later | |
527 _conc_workers(NULL), // may be set later | |
528 _abort_preclean(false), | |
529 _start_sampling(false), | |
530 _between_prologue_and_epilogue(false), | |
531 _markBitMap(0, Mutex::leaf + 1, "CMS_markBitMap_lock"), | |
532 _perm_gen_verify_bit_map(0, -1 /* no mutex */, "No_lock"), | |
533 _modUnionTable((CardTableModRefBS::card_shift - LogHeapWordSize), | |
534 -1 /* lock-free */, "No_lock" /* dummy */), | |
535 _modUnionClosure(&_modUnionTable), | |
536 _modUnionClosurePar(&_modUnionTable), | |
143
b5489bb705c9
6662086: 6u4+, 7b11+: CMS never clears referents when -XX:+ParallelRefProcEnabled
ysr
parents:
113
diff
changeset
|
537 // Adjust my span to cover old (cms) gen and perm gen |
b5489bb705c9
6662086: 6u4+, 7b11+: CMS never clears referents when -XX:+ParallelRefProcEnabled
ysr
parents:
113
diff
changeset
|
538 _span(cmsGen->reserved()._union(permGen->reserved())), |
b5489bb705c9
6662086: 6u4+, 7b11+: CMS never clears referents when -XX:+ParallelRefProcEnabled
ysr
parents:
113
diff
changeset
|
539 // Construct the is_alive_closure with _span & markBitMap |
b5489bb705c9
6662086: 6u4+, 7b11+: CMS never clears referents when -XX:+ParallelRefProcEnabled
ysr
parents:
113
diff
changeset
|
540 _is_alive_closure(_span, &_markBitMap), |
0 | 541 _restart_addr(NULL), |
542 _overflow_list(NULL), | |
543 _preserved_oop_stack(NULL), | |
544 _preserved_mark_stack(NULL), | |
545 _stats(cmsGen), | |
546 _eden_chunk_array(NULL), // may be set in ctor body | |
547 _eden_chunk_capacity(0), // -- ditto -- | |
548 _eden_chunk_index(0), // -- ditto -- | |
549 _survivor_plab_array(NULL), // -- ditto -- | |
550 _survivor_chunk_array(NULL), // -- ditto -- | |
551 _survivor_chunk_capacity(0), // -- ditto -- | |
552 _survivor_chunk_index(0), // -- ditto -- | |
553 _ser_pmc_preclean_ovflw(0), | |
452
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
554 _ser_kac_preclean_ovflw(0), |
0 | 555 _ser_pmc_remark_ovflw(0), |
556 _par_pmc_remark_ovflw(0), | |
557 _ser_kac_ovflw(0), | |
558 _par_kac_ovflw(0), | |
559 #ifndef PRODUCT | |
560 _num_par_pushes(0), | |
561 #endif | |
562 _collection_count_start(0), | |
563 _verifying(false), | |
564 _icms_start_limit(NULL), | |
565 _icms_stop_limit(NULL), | |
566 _verification_mark_bm(0, Mutex::leaf + 1, "CMS_verification_mark_bm_lock"), | |
567 _completed_initialization(false), | |
568 _collector_policy(cp), | |
94
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
569 _should_unload_classes(false), |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
570 _concurrent_cycles_since_last_unload(0), |
798
fe1574da39fc
6848641: CMSCollector::_roots_scanning_options should be initialized
ysr
parents:
679
diff
changeset
|
571 _roots_scanning_options(0), |
1145
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
572 _inter_sweep_estimate(CMS_SweepWeight, CMS_SweepPadding), |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
573 _intra_sweep_estimate(CMS_SweepWeight, CMS_SweepPadding) |
0 | 574 { |
575 if (ExplicitGCInvokesConcurrentAndUnloadsClasses) { | |
576 ExplicitGCInvokesConcurrent = true; | |
577 } | |
578 // Now expand the span and allocate the collection support structures | |
579 // (MUT, marking bit map etc.) to cover both generations subject to | |
580 // collection. | |
581 | |
582 // First check that _permGen is adjacent to _cmsGen and above it. | |
583 assert( _cmsGen->reserved().word_size() > 0 | |
584 && _permGen->reserved().word_size() > 0, | |
585 "generations should not be of zero size"); | |
586 assert(_cmsGen->reserved().intersection(_permGen->reserved()).is_empty(), | |
587 "_cmsGen and _permGen should not overlap"); | |
588 assert(_cmsGen->reserved().end() == _permGen->reserved().start(), | |
589 "_cmsGen->end() different from _permGen->start()"); | |
590 | |
591 // For use by dirty card to oop closures. | |
592 _cmsGen->cmsSpace()->set_collector(this); | |
593 _permGen->cmsSpace()->set_collector(this); | |
594 | |
595 // Allocate MUT and marking bit map | |
596 { | |
597 MutexLockerEx x(_markBitMap.lock(), Mutex::_no_safepoint_check_flag); | |
598 if (!_markBitMap.allocate(_span)) { | |
599 warning("Failed to allocate CMS Bit Map"); | |
600 return; | |
601 } | |
602 assert(_markBitMap.covers(_span), "_markBitMap inconsistency?"); | |
603 } | |
604 { | |
605 _modUnionTable.allocate(_span); | |
606 assert(_modUnionTable.covers(_span), "_modUnionTable inconsistency?"); | |
607 } | |
608 | |
1284 | 609 if (!_markStack.allocate(MarkStackSize)) { |
0 | 610 warning("Failed to allocate CMS Marking Stack"); |
611 return; | |
612 } | |
613 if (!_revisitStack.allocate(CMSRevisitStackSize)) { | |
614 warning("Failed to allocate CMS Revisit Stack"); | |
615 return; | |
616 } | |
617 | |
618 // Support for multi-threaded concurrent phases | |
619 if (ParallelGCThreads > 0 && CMSConcurrentMTEnabled) { | |
1284 | 620 if (FLAG_IS_DEFAULT(ConcGCThreads)) { |
0 | 621 // just for now |
1284 | 622 FLAG_SET_DEFAULT(ConcGCThreads, (ParallelGCThreads + 3)/4); |
623 } | |
624 if (ConcGCThreads > 1) { | |
0 | 625 _conc_workers = new YieldingFlexibleWorkGang("Parallel CMS Threads", |
1284 | 626 ConcGCThreads, true); |
0 | 627 if (_conc_workers == NULL) { |
628 warning("GC/CMS: _conc_workers allocation failure: " | |
629 "forcing -CMSConcurrentMTEnabled"); | |
630 CMSConcurrentMTEnabled = false; | |
631 } | |
632 } else { | |
633 CMSConcurrentMTEnabled = false; | |
634 } | |
635 } | |
636 if (!CMSConcurrentMTEnabled) { | |
1284 | 637 ConcGCThreads = 0; |
0 | 638 } else { |
639 // Turn off CMSCleanOnEnter optimization temporarily for | |
640 // the MT case where it's not fixed yet; see 6178663. | |
641 CMSCleanOnEnter = false; | |
642 } | |
1284 | 643 assert((_conc_workers != NULL) == (ConcGCThreads > 1), |
0 | 644 "Inconsistency"); |
645 | |
646 // Parallel task queues; these are shared for the | |
647 // concurrent and stop-world phases of CMS, but | |
648 // are not shared with parallel scavenge (ParNew). | |
649 { | |
650 uint i; | |
1284 | 651 uint num_queues = (uint) MAX2(ParallelGCThreads, ConcGCThreads); |
0 | 652 |
653 if ((CMSParallelRemarkEnabled || CMSConcurrentMTEnabled | |
654 || ParallelRefProcEnabled) | |
655 && num_queues > 0) { | |
656 _task_queues = new OopTaskQueueSet(num_queues); | |
657 if (_task_queues == NULL) { | |
658 warning("task_queues allocation failure."); | |
659 return; | |
660 } | |
661 _hash_seed = NEW_C_HEAP_ARRAY(int, num_queues); | |
662 if (_hash_seed == NULL) { | |
663 warning("_hash_seed array allocation failure"); | |
664 return; | |
665 } | |
666 | |
667 // XXX use a global constant instead of 64! | |
668 typedef struct OopTaskQueuePadded { | |
669 OopTaskQueue work_queue; | |
670 char pad[64 - sizeof(OopTaskQueue)]; // prevent false sharing | |
671 } OopTaskQueuePadded; | |
672 | |
673 for (i = 0; i < num_queues; i++) { | |
674 OopTaskQueuePadded *q_padded = new OopTaskQueuePadded(); | |
675 if (q_padded == NULL) { | |
676 warning("work_queue allocation failure."); | |
677 return; | |
678 } | |
679 _task_queues->register_queue(i, &q_padded->work_queue); | |
680 } | |
681 for (i = 0; i < num_queues; i++) { | |
682 _task_queues->queue(i)->initialize(); | |
683 _hash_seed[i] = 17; // copied from ParNew | |
684 } | |
685 } | |
686 } | |
687 | |
94
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
688 _cmsGen ->init_initiating_occupancy(CMSInitiatingOccupancyFraction, CMSTriggerRatio); |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
689 _permGen->init_initiating_occupancy(CMSInitiatingPermOccupancyFraction, CMSTriggerPermRatio); |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
690 |
0 | 691 // Clip CMSBootstrapOccupancy between 0 and 100. |
94
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
692 _bootstrap_occupancy = ((double)MIN2((uintx)100, MAX2((uintx)0, CMSBootstrapOccupancy))) |
0 | 693 /(double)100; |
694 | |
695 _full_gcs_since_conc_gc = 0; | |
696 | |
697 // Now tell CMS generations the identity of their collector | |
698 ConcurrentMarkSweepGeneration::set_collector(this); | |
699 | |
700 // Create & start a CMS thread for this CMS collector | |
701 _cmsThread = ConcurrentMarkSweepThread::start(this); | |
702 assert(cmsThread() != NULL, "CMS Thread should have been created"); | |
703 assert(cmsThread()->collector() == this, | |
704 "CMS Thread should refer to this gen"); | |
705 assert(CGC_lock != NULL, "Where's the CGC_lock?"); | |
706 | |
707 // Support for parallelizing young gen rescan | |
708 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
709 _young_gen = gch->prev_gen(_cmsGen); | |
710 if (gch->supports_inline_contig_alloc()) { | |
711 _top_addr = gch->top_addr(); | |
712 _end_addr = gch->end_addr(); | |
713 assert(_young_gen != NULL, "no _young_gen"); | |
714 _eden_chunk_index = 0; | |
715 _eden_chunk_capacity = (_young_gen->max_capacity()+CMSSamplingGrain)/CMSSamplingGrain; | |
716 _eden_chunk_array = NEW_C_HEAP_ARRAY(HeapWord*, _eden_chunk_capacity); | |
717 if (_eden_chunk_array == NULL) { | |
718 _eden_chunk_capacity = 0; | |
719 warning("GC/CMS: _eden_chunk_array allocation failure"); | |
720 } | |
721 } | |
722 assert(_eden_chunk_array != NULL || _eden_chunk_capacity == 0, "Error"); | |
723 | |
724 // Support for parallelizing survivor space rescan | |
725 if (CMSParallelRemarkEnabled && CMSParallelSurvivorRemarkEnabled) { | |
1289
d47555d7aca8
6910182: CMS: assert(_cursor[j] == _survivor_plab_array[j].end(),"Ctl pt invariant")
jmasa
parents:
1284
diff
changeset
|
726 const size_t max_plab_samples = |
d47555d7aca8
6910182: CMS: assert(_cursor[j] == _survivor_plab_array[j].end(),"Ctl pt invariant")
jmasa
parents:
1284
diff
changeset
|
727 ((DefNewGeneration*)_young_gen)->max_survivor_size()/MinTLABSize; |
d47555d7aca8
6910182: CMS: assert(_cursor[j] == _survivor_plab_array[j].end(),"Ctl pt invariant")
jmasa
parents:
1284
diff
changeset
|
728 |
0 | 729 _survivor_plab_array = NEW_C_HEAP_ARRAY(ChunkArray, ParallelGCThreads); |
730 _survivor_chunk_array = NEW_C_HEAP_ARRAY(HeapWord*, 2*max_plab_samples); | |
731 _cursor = NEW_C_HEAP_ARRAY(size_t, ParallelGCThreads); | |
732 if (_survivor_plab_array == NULL || _survivor_chunk_array == NULL | |
733 || _cursor == NULL) { | |
734 warning("Failed to allocate survivor plab/chunk array"); | |
735 if (_survivor_plab_array != NULL) { | |
736 FREE_C_HEAP_ARRAY(ChunkArray, _survivor_plab_array); | |
737 _survivor_plab_array = NULL; | |
738 } | |
739 if (_survivor_chunk_array != NULL) { | |
740 FREE_C_HEAP_ARRAY(HeapWord*, _survivor_chunk_array); | |
741 _survivor_chunk_array = NULL; | |
742 } | |
743 if (_cursor != NULL) { | |
744 FREE_C_HEAP_ARRAY(size_t, _cursor); | |
745 _cursor = NULL; | |
746 } | |
747 } else { | |
748 _survivor_chunk_capacity = 2*max_plab_samples; | |
749 for (uint i = 0; i < ParallelGCThreads; i++) { | |
750 HeapWord** vec = NEW_C_HEAP_ARRAY(HeapWord*, max_plab_samples); | |
751 if (vec == NULL) { | |
752 warning("Failed to allocate survivor plab array"); | |
753 for (int j = i; j > 0; j--) { | |
754 FREE_C_HEAP_ARRAY(HeapWord*, _survivor_plab_array[j-1].array()); | |
755 } | |
756 FREE_C_HEAP_ARRAY(ChunkArray, _survivor_plab_array); | |
757 FREE_C_HEAP_ARRAY(HeapWord*, _survivor_chunk_array); | |
758 _survivor_plab_array = NULL; | |
759 _survivor_chunk_array = NULL; | |
760 _survivor_chunk_capacity = 0; | |
761 break; | |
762 } else { | |
763 ChunkArray* cur = | |
764 ::new (&_survivor_plab_array[i]) ChunkArray(vec, | |
765 max_plab_samples); | |
766 assert(cur->end() == 0, "Should be 0"); | |
767 assert(cur->array() == vec, "Should be vec"); | |
768 assert(cur->capacity() == max_plab_samples, "Error"); | |
769 } | |
770 } | |
771 } | |
772 } | |
773 assert( ( _survivor_plab_array != NULL | |
774 && _survivor_chunk_array != NULL) | |
775 || ( _survivor_chunk_capacity == 0 | |
776 && _survivor_chunk_index == 0), | |
777 "Error"); | |
778 | |
779 // Choose what strong roots should be scanned depending on verification options | |
780 // and perm gen collection mode. | |
781 if (!CMSClassUnloadingEnabled) { | |
782 // If class unloading is disabled we want to include all classes into the root set. | |
783 add_root_scanning_option(SharedHeap::SO_AllClasses); | |
784 } else { | |
785 add_root_scanning_option(SharedHeap::SO_SystemClasses); | |
786 } | |
787 | |
788 NOT_PRODUCT(_overflow_counter = CMSMarkStackOverflowInterval;) | |
789 _gc_counters = new CollectorCounters("CMS", 1); | |
790 _completed_initialization = true; | |
1145
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
791 _inter_sweep_timer.start(); // start of time |
1518
3bfae429e2cf
6948537: CMS: BOT walkers observe out-of-thin-air zeros on sun4v sparc/CMT
ysr
parents:
1387
diff
changeset
|
792 #ifdef SPARC |
3bfae429e2cf
6948537: CMS: BOT walkers observe out-of-thin-air zeros on sun4v sparc/CMT
ysr
parents:
1387
diff
changeset
|
793 // Issue a stern warning, but allow use for experimentation and debugging. |
3bfae429e2cf
6948537: CMS: BOT walkers observe out-of-thin-air zeros on sun4v sparc/CMT
ysr
parents:
1387
diff
changeset
|
794 if (VM_Version::is_sun4v() && UseMemSetInBOT) { |
3bfae429e2cf
6948537: CMS: BOT walkers observe out-of-thin-air zeros on sun4v sparc/CMT
ysr
parents:
1387
diff
changeset
|
795 assert(!FLAG_IS_DEFAULT(UseMemSetInBOT), "Error"); |
3bfae429e2cf
6948537: CMS: BOT walkers observe out-of-thin-air zeros on sun4v sparc/CMT
ysr
parents:
1387
diff
changeset
|
796 warning("Experimental flag -XX:+UseMemSetInBOT is known to cause instability" |
3bfae429e2cf
6948537: CMS: BOT walkers observe out-of-thin-air zeros on sun4v sparc/CMT
ysr
parents:
1387
diff
changeset
|
797 " on sun4v; please understand that you are using at your own risk!"); |
3bfae429e2cf
6948537: CMS: BOT walkers observe out-of-thin-air zeros on sun4v sparc/CMT
ysr
parents:
1387
diff
changeset
|
798 } |
3bfae429e2cf
6948537: CMS: BOT walkers observe out-of-thin-air zeros on sun4v sparc/CMT
ysr
parents:
1387
diff
changeset
|
799 #endif |
0 | 800 } |
801 | |
802 const char* ConcurrentMarkSweepGeneration::name() const { | |
803 return "concurrent mark-sweep generation"; | |
804 } | |
805 void ConcurrentMarkSweepGeneration::update_counters() { | |
806 if (UsePerfData) { | |
807 _space_counters->update_all(); | |
808 _gen_counters->update_all(); | |
809 } | |
810 } | |
811 | |
812 // this is an optimized version of update_counters(). it takes the | |
813 // used value as a parameter rather than computing it. | |
814 // | |
815 void ConcurrentMarkSweepGeneration::update_counters(size_t used) { | |
816 if (UsePerfData) { | |
817 _space_counters->update_used(used); | |
818 _space_counters->update_capacity(); | |
819 _gen_counters->update_all(); | |
820 } | |
821 } | |
822 | |
823 void ConcurrentMarkSweepGeneration::print() const { | |
824 Generation::print(); | |
825 cmsSpace()->print(); | |
826 } | |
827 | |
828 #ifndef PRODUCT | |
829 void ConcurrentMarkSweepGeneration::print_statistics() { | |
830 cmsSpace()->printFLCensus(0); | |
831 } | |
832 #endif | |
833 | |
834 void ConcurrentMarkSweepGeneration::printOccupancy(const char *s) { | |
835 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
836 if (PrintGCDetails) { | |
837 if (Verbose) { | |
838 gclog_or_tty->print(" [%d %s-%s: "SIZE_FORMAT"("SIZE_FORMAT")]", | |
839 level(), short_name(), s, used(), capacity()); | |
840 } else { | |
841 gclog_or_tty->print(" [%d %s-%s: "SIZE_FORMAT"K("SIZE_FORMAT"K)]", | |
842 level(), short_name(), s, used() / K, capacity() / K); | |
843 } | |
844 } | |
845 if (Verbose) { | |
846 gclog_or_tty->print(" "SIZE_FORMAT"("SIZE_FORMAT")", | |
847 gch->used(), gch->capacity()); | |
848 } else { | |
849 gclog_or_tty->print(" "SIZE_FORMAT"K("SIZE_FORMAT"K)", | |
850 gch->used() / K, gch->capacity() / K); | |
851 } | |
852 } | |
853 | |
854 size_t | |
855 ConcurrentMarkSweepGeneration::contiguous_available() const { | |
856 // dld proposes an improvement in precision here. If the committed | |
857 // part of the space ends in a free block we should add that to | |
858 // uncommitted size in the calculation below. Will make this | |
859 // change later, staying with the approximation below for the | |
860 // time being. -- ysr. | |
861 return MAX2(_virtual_space.uncommitted_size(), unsafe_max_alloc_nogc()); | |
862 } | |
863 | |
864 size_t | |
865 ConcurrentMarkSweepGeneration::unsafe_max_alloc_nogc() const { | |
866 return _cmsSpace->max_alloc_in_words() * HeapWordSize; | |
867 } | |
868 | |
869 size_t ConcurrentMarkSweepGeneration::max_available() const { | |
870 return free() + _virtual_space.uncommitted_size(); | |
871 } | |
872 | |
873 bool ConcurrentMarkSweepGeneration::promotion_attempt_is_safe( | |
874 size_t max_promotion_in_bytes, | |
875 bool younger_handles_promotion_failure) const { | |
876 | |
877 // This is the most conservative test. Full promotion is | |
878 // guaranteed if this is used. The multiplicative factor is to | |
879 // account for the worst case "dilatation". | |
880 double adjusted_max_promo_bytes = _dilatation_factor * max_promotion_in_bytes; | |
881 if (adjusted_max_promo_bytes > (double)max_uintx) { // larger than size_t | |
882 adjusted_max_promo_bytes = (double)max_uintx; | |
883 } | |
884 bool result = (max_contiguous_available() >= (size_t)adjusted_max_promo_bytes); | |
885 | |
886 if (younger_handles_promotion_failure && !result) { | |
887 // Full promotion is not guaranteed because fragmentation | |
888 // of the cms generation can prevent the full promotion. | |
889 result = (max_available() >= (size_t)adjusted_max_promo_bytes); | |
890 | |
891 if (!result) { | |
892 // With promotion failure handling the test for the ability | |
893 // to support the promotion does not have to be guaranteed. | |
894 // Use an average of the amount promoted. | |
895 result = max_available() >= (size_t) | |
896 gc_stats()->avg_promoted()->padded_average(); | |
897 if (PrintGC && Verbose && result) { | |
898 gclog_or_tty->print_cr( | |
899 "\nConcurrentMarkSweepGeneration::promotion_attempt_is_safe" | |
900 " max_available: " SIZE_FORMAT | |
901 " avg_promoted: " SIZE_FORMAT, | |
902 max_available(), (size_t) | |
903 gc_stats()->avg_promoted()->padded_average()); | |
904 } | |
905 } else { | |
906 if (PrintGC && Verbose) { | |
907 gclog_or_tty->print_cr( | |
908 "\nConcurrentMarkSweepGeneration::promotion_attempt_is_safe" | |
909 " max_available: " SIZE_FORMAT | |
910 " adj_max_promo_bytes: " SIZE_FORMAT, | |
911 max_available(), (size_t)adjusted_max_promo_bytes); | |
912 } | |
913 } | |
914 } else { | |
915 if (PrintGC && Verbose) { | |
916 gclog_or_tty->print_cr( | |
917 "\nConcurrentMarkSweepGeneration::promotion_attempt_is_safe" | |
918 " contiguous_available: " SIZE_FORMAT | |
919 " adj_max_promo_bytes: " SIZE_FORMAT, | |
920 max_contiguous_available(), (size_t)adjusted_max_promo_bytes); | |
921 } | |
922 } | |
923 return result; | |
924 } | |
925 | |
1145
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
926 // At a promotion failure dump information on block layout in heap |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
927 // (cms old generation). |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
928 void ConcurrentMarkSweepGeneration::promotion_failure_occurred() { |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
929 if (CMSDumpAtPromotionFailure) { |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
930 cmsSpace()->dump_at_safepoint_with_locks(collector(), gclog_or_tty); |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
931 } |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
932 } |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
933 |
0 | 934 CompactibleSpace* |
935 ConcurrentMarkSweepGeneration::first_compaction_space() const { | |
936 return _cmsSpace; | |
937 } | |
938 | |
939 void ConcurrentMarkSweepGeneration::reset_after_compaction() { | |
940 // Clear the promotion information. These pointers can be adjusted | |
941 // along with all the other pointers into the heap but | |
942 // compaction is expected to be a rare event with | |
943 // a heap using cms so don't do it without seeing the need. | |
944 if (ParallelGCThreads > 0) { | |
945 for (uint i = 0; i < ParallelGCThreads; i++) { | |
946 _par_gc_thread_states[i]->promo.reset(); | |
947 } | |
948 } | |
949 } | |
950 | |
951 void ConcurrentMarkSweepGeneration::space_iterate(SpaceClosure* blk, bool usedOnly) { | |
952 blk->do_space(_cmsSpace); | |
953 } | |
954 | |
955 void ConcurrentMarkSweepGeneration::compute_new_size() { | |
956 assert_locked_or_safepoint(Heap_lock); | |
957 | |
958 // If incremental collection failed, we just want to expand | |
959 // to the limit. | |
960 if (incremental_collection_failed()) { | |
961 clear_incremental_collection_failed(); | |
962 grow_to_reserved(); | |
963 return; | |
964 } | |
965 | |
966 size_t expand_bytes = 0; | |
967 double free_percentage = ((double) free()) / capacity(); | |
968 double desired_free_percentage = (double) MinHeapFreeRatio / 100; | |
969 double maximum_free_percentage = (double) MaxHeapFreeRatio / 100; | |
970 | |
971 // compute expansion delta needed for reaching desired free percentage | |
972 if (free_percentage < desired_free_percentage) { | |
973 size_t desired_capacity = (size_t)(used() / ((double) 1 - desired_free_percentage)); | |
974 assert(desired_capacity >= capacity(), "invalid expansion size"); | |
975 expand_bytes = MAX2(desired_capacity - capacity(), MinHeapDeltaBytes); | |
976 } | |
977 if (expand_bytes > 0) { | |
978 if (PrintGCDetails && Verbose) { | |
979 size_t desired_capacity = (size_t)(used() / ((double) 1 - desired_free_percentage)); | |
980 gclog_or_tty->print_cr("\nFrom compute_new_size: "); | |
981 gclog_or_tty->print_cr(" Free fraction %f", free_percentage); | |
982 gclog_or_tty->print_cr(" Desired free fraction %f", | |
983 desired_free_percentage); | |
984 gclog_or_tty->print_cr(" Maximum free fraction %f", | |
985 maximum_free_percentage); | |
986 gclog_or_tty->print_cr(" Capactiy "SIZE_FORMAT, capacity()/1000); | |
987 gclog_or_tty->print_cr(" Desired capacity "SIZE_FORMAT, | |
988 desired_capacity/1000); | |
989 int prev_level = level() - 1; | |
990 if (prev_level >= 0) { | |
991 size_t prev_size = 0; | |
992 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
993 Generation* prev_gen = gch->_gens[prev_level]; | |
994 prev_size = prev_gen->capacity(); | |
995 gclog_or_tty->print_cr(" Younger gen size "SIZE_FORMAT, | |
996 prev_size/1000); | |
997 } | |
998 gclog_or_tty->print_cr(" unsafe_max_alloc_nogc "SIZE_FORMAT, | |
999 unsafe_max_alloc_nogc()/1000); | |
1000 gclog_or_tty->print_cr(" contiguous available "SIZE_FORMAT, | |
1001 contiguous_available()/1000); | |
1002 gclog_or_tty->print_cr(" Expand by "SIZE_FORMAT" (bytes)", | |
1003 expand_bytes); | |
1004 } | |
1005 // safe if expansion fails | |
1006 expand(expand_bytes, 0, CMSExpansionCause::_satisfy_free_ratio); | |
1007 if (PrintGCDetails && Verbose) { | |
1008 gclog_or_tty->print_cr(" Expanded free fraction %f", | |
1009 ((double) free()) / capacity()); | |
1010 } | |
1011 } | |
1012 } | |
1013 | |
1014 Mutex* ConcurrentMarkSweepGeneration::freelistLock() const { | |
1015 return cmsSpace()->freelistLock(); | |
1016 } | |
1017 | |
1018 HeapWord* ConcurrentMarkSweepGeneration::allocate(size_t size, | |
1019 bool tlab) { | |
1020 CMSSynchronousYieldRequest yr; | |
1021 MutexLockerEx x(freelistLock(), | |
1022 Mutex::_no_safepoint_check_flag); | |
1023 return have_lock_and_allocate(size, tlab); | |
1024 } | |
1025 | |
1026 HeapWord* ConcurrentMarkSweepGeneration::have_lock_and_allocate(size_t size, | |
1027 bool tlab) { | |
1028 assert_lock_strong(freelistLock()); | |
1029 size_t adjustedSize = CompactibleFreeListSpace::adjustObjectSize(size); | |
1030 HeapWord* res = cmsSpace()->allocate(adjustedSize); | |
1031 // Allocate the object live (grey) if the background collector has | |
1032 // started marking. This is necessary because the marker may | |
1033 // have passed this address and consequently this object will | |
1034 // not otherwise be greyed and would be incorrectly swept up. | |
1035 // Note that if this object contains references, the writing | |
1036 // of those references will dirty the card containing this object | |
1037 // allowing the object to be blackened (and its references scanned) | |
1038 // either during a preclean phase or at the final checkpoint. | |
1039 if (res != NULL) { | |
1040 collector()->direct_allocated(res, adjustedSize); | |
1041 _direct_allocated_words += adjustedSize; | |
1042 // allocation counters | |
1043 NOT_PRODUCT( | |
1044 _numObjectsAllocated++; | |
1045 _numWordsAllocated += (int)adjustedSize; | |
1046 ) | |
1047 } | |
1048 return res; | |
1049 } | |
1050 | |
1051 // In the case of direct allocation by mutators in a generation that | |
1052 // is being concurrently collected, the object must be allocated | |
1053 // live (grey) if the background collector has started marking. | |
1054 // This is necessary because the marker may | |
1055 // have passed this address and consequently this object will | |
1056 // not otherwise be greyed and would be incorrectly swept up. | |
1057 // Note that if this object contains references, the writing | |
1058 // of those references will dirty the card containing this object | |
1059 // allowing the object to be blackened (and its references scanned) | |
1060 // either during a preclean phase or at the final checkpoint. | |
1061 void CMSCollector::direct_allocated(HeapWord* start, size_t size) { | |
1062 assert(_markBitMap.covers(start, size), "Out of bounds"); | |
1063 if (_collectorState >= Marking) { | |
1064 MutexLockerEx y(_markBitMap.lock(), | |
1065 Mutex::_no_safepoint_check_flag); | |
1066 // [see comments preceding SweepClosure::do_blk() below for details] | |
1067 // 1. need to mark the object as live so it isn't collected | |
1068 // 2. need to mark the 2nd bit to indicate the object may be uninitialized | |
1069 // 3. need to mark the end of the object so sweeper can skip over it | |
1070 // if it's uninitialized when the sweeper reaches it. | |
1071 _markBitMap.mark(start); // object is live | |
1072 _markBitMap.mark(start + 1); // object is potentially uninitialized? | |
1073 _markBitMap.mark(start + size - 1); | |
1074 // mark end of object | |
1075 } | |
1076 // check that oop looks uninitialized | |
187 | 1077 assert(oop(start)->klass_or_null() == NULL, "_klass should be NULL"); |
0 | 1078 } |
1079 | |
1080 void CMSCollector::promoted(bool par, HeapWord* start, | |
1081 bool is_obj_array, size_t obj_size) { | |
1082 assert(_markBitMap.covers(start), "Out of bounds"); | |
1083 // See comment in direct_allocated() about when objects should | |
1084 // be allocated live. | |
1085 if (_collectorState >= Marking) { | |
1086 // we already hold the marking bit map lock, taken in | |
1087 // the prologue | |
1088 if (par) { | |
1089 _markBitMap.par_mark(start); | |
1090 } else { | |
1091 _markBitMap.mark(start); | |
1092 } | |
1093 // We don't need to mark the object as uninitialized (as | |
1094 // in direct_allocated above) because this is being done with the | |
1095 // world stopped and the object will be initialized by the | |
1096 // time the sweeper gets to look at it. | |
1097 assert(SafepointSynchronize::is_at_safepoint(), | |
1098 "expect promotion only at safepoints"); | |
1099 | |
1100 if (_collectorState < Sweeping) { | |
1101 // Mark the appropriate cards in the modUnionTable, so that | |
1102 // this object gets scanned before the sweep. If this is | |
1103 // not done, CMS generation references in the object might | |
1104 // not get marked. | |
1105 // For the case of arrays, which are otherwise precisely | |
1106 // marked, we need to dirty the entire array, not just its head. | |
1107 if (is_obj_array) { | |
1108 // The [par_]mark_range() method expects mr.end() below to | |
1109 // be aligned to the granularity of a bit's representation | |
1110 // in the heap. In the case of the MUT below, that's a | |
1111 // card size. | |
1112 MemRegion mr(start, | |
1113 (HeapWord*)round_to((intptr_t)(start + obj_size), | |
1114 CardTableModRefBS::card_size /* bytes */)); | |
1115 if (par) { | |
1116 _modUnionTable.par_mark_range(mr); | |
1117 } else { | |
1118 _modUnionTable.mark_range(mr); | |
1119 } | |
1120 } else { // not an obj array; we can just mark the head | |
1121 if (par) { | |
1122 _modUnionTable.par_mark(start); | |
1123 } else { | |
1124 _modUnionTable.mark(start); | |
1125 } | |
1126 } | |
1127 } | |
1128 } | |
1129 } | |
1130 | |
1131 static inline size_t percent_of_space(Space* space, HeapWord* addr) | |
1132 { | |
1133 size_t delta = pointer_delta(addr, space->bottom()); | |
1134 return (size_t)(delta * 100.0 / (space->capacity() / HeapWordSize)); | |
1135 } | |
1136 | |
1137 void CMSCollector::icms_update_allocation_limits() | |
1138 { | |
1139 Generation* gen0 = GenCollectedHeap::heap()->get_gen(0); | |
1140 EdenSpace* eden = gen0->as_DefNewGeneration()->eden(); | |
1141 | |
1142 const unsigned int duty_cycle = stats().icms_update_duty_cycle(); | |
1143 if (CMSTraceIncrementalPacing) { | |
1144 stats().print(); | |
1145 } | |
1146 | |
1147 assert(duty_cycle <= 100, "invalid duty cycle"); | |
1148 if (duty_cycle != 0) { | |
1149 // The duty_cycle is a percentage between 0 and 100; convert to words and | |
1150 // then compute the offset from the endpoints of the space. | |
1151 size_t free_words = eden->free() / HeapWordSize; | |
1152 double free_words_dbl = (double)free_words; | |
1153 size_t duty_cycle_words = (size_t)(free_words_dbl * duty_cycle / 100.0); | |
1154 size_t offset_words = (free_words - duty_cycle_words) / 2; | |
1155 | |
1156 _icms_start_limit = eden->top() + offset_words; | |
1157 _icms_stop_limit = eden->end() - offset_words; | |
1158 | |
1159 // The limits may be adjusted (shifted to the right) by | |
1160 // CMSIncrementalOffset, to allow the application more mutator time after a | |
1161 // young gen gc (when all mutators were stopped) and before CMS starts and | |
1162 // takes away one or more cpus. | |
1163 if (CMSIncrementalOffset != 0) { | |
1164 double adjustment_dbl = free_words_dbl * CMSIncrementalOffset / 100.0; | |
1165 size_t adjustment = (size_t)adjustment_dbl; | |
1166 HeapWord* tmp_stop = _icms_stop_limit + adjustment; | |
1167 if (tmp_stop > _icms_stop_limit && tmp_stop < eden->end()) { | |
1168 _icms_start_limit += adjustment; | |
1169 _icms_stop_limit = tmp_stop; | |
1170 } | |
1171 } | |
1172 } | |
1173 if (duty_cycle == 0 || (_icms_start_limit == _icms_stop_limit)) { | |
1174 _icms_start_limit = _icms_stop_limit = eden->end(); | |
1175 } | |
1176 | |
1177 // Install the new start limit. | |
1178 eden->set_soft_end(_icms_start_limit); | |
1179 | |
1180 if (CMSTraceIncrementalMode) { | |
1181 gclog_or_tty->print(" icms alloc limits: " | |
1182 PTR_FORMAT "," PTR_FORMAT | |
1183 " (" SIZE_FORMAT "%%," SIZE_FORMAT "%%) ", | |
1184 _icms_start_limit, _icms_stop_limit, | |
1185 percent_of_space(eden, _icms_start_limit), | |
1186 percent_of_space(eden, _icms_stop_limit)); | |
1187 if (Verbose) { | |
1188 gclog_or_tty->print("eden: "); | |
1189 eden->print_on(gclog_or_tty); | |
1190 } | |
1191 } | |
1192 } | |
1193 | |
1194 // Any changes here should try to maintain the invariant | |
1195 // that if this method is called with _icms_start_limit | |
1196 // and _icms_stop_limit both NULL, then it should return NULL | |
1197 // and not notify the icms thread. | |
1198 HeapWord* | |
1199 CMSCollector::allocation_limit_reached(Space* space, HeapWord* top, | |
1200 size_t word_size) | |
1201 { | |
1202 // A start_limit equal to end() means the duty cycle is 0, so treat that as a | |
1203 // nop. | |
1204 if (CMSIncrementalMode && _icms_start_limit != space->end()) { | |
1205 if (top <= _icms_start_limit) { | |
1206 if (CMSTraceIncrementalMode) { | |
1207 space->print_on(gclog_or_tty); | |
1208 gclog_or_tty->stamp(); | |
1209 gclog_or_tty->print_cr(" start limit top=" PTR_FORMAT | |
1210 ", new limit=" PTR_FORMAT | |
1211 " (" SIZE_FORMAT "%%)", | |
1212 top, _icms_stop_limit, | |
1213 percent_of_space(space, _icms_stop_limit)); | |
1214 } | |
1215 ConcurrentMarkSweepThread::start_icms(); | |
1216 assert(top < _icms_stop_limit, "Tautology"); | |
1217 if (word_size < pointer_delta(_icms_stop_limit, top)) { | |
1218 return _icms_stop_limit; | |
1219 } | |
1220 | |
1221 // The allocation will cross both the _start and _stop limits, so do the | |
1222 // stop notification also and return end(). | |
1223 if (CMSTraceIncrementalMode) { | |
1224 space->print_on(gclog_or_tty); | |
1225 gclog_or_tty->stamp(); | |
1226 gclog_or_tty->print_cr(" +stop limit top=" PTR_FORMAT | |
1227 ", new limit=" PTR_FORMAT | |
1228 " (" SIZE_FORMAT "%%)", | |
1229 top, space->end(), | |
1230 percent_of_space(space, space->end())); | |
1231 } | |
1232 ConcurrentMarkSweepThread::stop_icms(); | |
1233 return space->end(); | |
1234 } | |
1235 | |
1236 if (top <= _icms_stop_limit) { | |
1237 if (CMSTraceIncrementalMode) { | |
1238 space->print_on(gclog_or_tty); | |
1239 gclog_or_tty->stamp(); | |
1240 gclog_or_tty->print_cr(" stop limit top=" PTR_FORMAT | |
1241 ", new limit=" PTR_FORMAT | |
1242 " (" SIZE_FORMAT "%%)", | |
1243 top, space->end(), | |
1244 percent_of_space(space, space->end())); | |
1245 } | |
1246 ConcurrentMarkSweepThread::stop_icms(); | |
1247 return space->end(); | |
1248 } | |
1249 | |
1250 if (CMSTraceIncrementalMode) { | |
1251 space->print_on(gclog_or_tty); | |
1252 gclog_or_tty->stamp(); | |
1253 gclog_or_tty->print_cr(" end limit top=" PTR_FORMAT | |
1254 ", new limit=" PTR_FORMAT, | |
1255 top, NULL); | |
1256 } | |
1257 } | |
1258 | |
1259 return NULL; | |
1260 } | |
1261 | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
1262 oop ConcurrentMarkSweepGeneration::promote(oop obj, size_t obj_size) { |
0 | 1263 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in"); |
1264 // allocate, copy and if necessary update promoinfo -- | |
1265 // delegate to underlying space. | |
1266 assert_lock_strong(freelistLock()); | |
1267 | |
1268 #ifndef PRODUCT | |
1269 if (Universe::heap()->promotion_should_fail()) { | |
1270 return NULL; | |
1271 } | |
1272 #endif // #ifndef PRODUCT | |
1273 | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
1274 oop res = _cmsSpace->promote(obj, obj_size); |
0 | 1275 if (res == NULL) { |
1276 // expand and retry | |
1277 size_t s = _cmsSpace->expansionSpaceRequired(obj_size); // HeapWords | |
1278 expand(s*HeapWordSize, MinHeapDeltaBytes, | |
1279 CMSExpansionCause::_satisfy_promotion); | |
1280 // Since there's currently no next generation, we don't try to promote | |
1281 // into a more senior generation. | |
1282 assert(next_gen() == NULL, "assumption, based upon which no attempt " | |
1283 "is made to pass on a possibly failing " | |
1284 "promotion to next generation"); | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
1285 res = _cmsSpace->promote(obj, obj_size); |
0 | 1286 } |
1287 if (res != NULL) { | |
1288 // See comment in allocate() about when objects should | |
1289 // be allocated live. | |
1290 assert(obj->is_oop(), "Will dereference klass pointer below"); | |
1291 collector()->promoted(false, // Not parallel | |
1292 (HeapWord*)res, obj->is_objArray(), obj_size); | |
1293 // promotion counters | |
1294 NOT_PRODUCT( | |
1295 _numObjectsPromoted++; | |
1296 _numWordsPromoted += | |
1297 (int)(CompactibleFreeListSpace::adjustObjectSize(obj->size())); | |
1298 ) | |
1299 } | |
1300 return res; | |
1301 } | |
1302 | |
1303 | |
1304 HeapWord* | |
1305 ConcurrentMarkSweepGeneration::allocation_limit_reached(Space* space, | |
1306 HeapWord* top, | |
1307 size_t word_sz) | |
1308 { | |
1309 return collector()->allocation_limit_reached(space, top, word_sz); | |
1310 } | |
1311 | |
1312 // Things to support parallel young-gen collection. | |
1313 oop | |
1314 ConcurrentMarkSweepGeneration::par_promote(int thread_num, | |
1315 oop old, markOop m, | |
1316 size_t word_sz) { | |
1317 #ifndef PRODUCT | |
1318 if (Universe::heap()->promotion_should_fail()) { | |
1319 return NULL; | |
1320 } | |
1321 #endif // #ifndef PRODUCT | |
1322 | |
1323 CMSParGCThreadState* ps = _par_gc_thread_states[thread_num]; | |
1324 PromotionInfo* promoInfo = &ps->promo; | |
1325 // if we are tracking promotions, then first ensure space for | |
1326 // promotion (including spooling space for saving header if necessary). | |
1327 // then allocate and copy, then track promoted info if needed. | |
1328 // When tracking (see PromotionInfo::track()), the mark word may | |
1329 // be displaced and in this case restoration of the mark word | |
1330 // occurs in the (oop_since_save_marks_)iterate phase. | |
1331 if (promoInfo->tracking() && !promoInfo->ensure_spooling_space()) { | |
1332 // Out of space for allocating spooling buffers; | |
1333 // try expanding and allocating spooling buffers. | |
1334 if (!expand_and_ensure_spooling_space(promoInfo)) { | |
1335 return NULL; | |
1336 } | |
1337 } | |
1338 assert(promoInfo->has_spooling_space(), "Control point invariant"); | |
1339 HeapWord* obj_ptr = ps->lab.alloc(word_sz); | |
1340 if (obj_ptr == NULL) { | |
1341 obj_ptr = expand_and_par_lab_allocate(ps, word_sz); | |
1342 if (obj_ptr == NULL) { | |
1343 return NULL; | |
1344 } | |
1345 } | |
1346 oop obj = oop(obj_ptr); | |
187 | 1347 assert(obj->klass_or_null() == NULL, "Object should be uninitialized here."); |
0 | 1348 // Otherwise, copy the object. Here we must be careful to insert the |
1349 // klass pointer last, since this marks the block as an allocated object. | |
187 | 1350 // Except with compressed oops it's the mark word. |
0 | 1351 HeapWord* old_ptr = (HeapWord*)old; |
1352 if (word_sz > (size_t)oopDesc::header_size()) { | |
1353 Copy::aligned_disjoint_words(old_ptr + oopDesc::header_size(), | |
1354 obj_ptr + oopDesc::header_size(), | |
1355 word_sz - oopDesc::header_size()); | |
1356 } | |
187 | 1357 |
1358 if (UseCompressedOops) { | |
1359 // Copy gap missed by (aligned) header size calculation above | |
1360 obj->set_klass_gap(old->klass_gap()); | |
1361 } | |
1362 | |
0 | 1363 // Restore the mark word copied above. |
1364 obj->set_mark(m); | |
187 | 1365 |
0 | 1366 // Now we can track the promoted object, if necessary. We take care |
1521 | 1367 // to delay the transition from uninitialized to full object |
0 | 1368 // (i.e., insertion of klass pointer) until after, so that it |
1369 // atomically becomes a promoted object. | |
1370 if (promoInfo->tracking()) { | |
1371 promoInfo->track((PromotedObject*)obj, old->klass()); | |
1372 } | |
187 | 1373 |
1374 // Finally, install the klass pointer (this should be volatile). | |
0 | 1375 obj->set_klass(old->klass()); |
1376 | |
1377 assert(old->is_oop(), "Will dereference klass ptr below"); | |
1378 collector()->promoted(true, // parallel | |
1379 obj_ptr, old->is_objArray(), word_sz); | |
1380 | |
1381 NOT_PRODUCT( | |
1382 Atomic::inc(&_numObjectsPromoted); | |
1383 Atomic::add((jint)CompactibleFreeListSpace::adjustObjectSize(obj->size()), | |
1384 &_numWordsPromoted); | |
1385 ) | |
1386 | |
1387 return obj; | |
1388 } | |
1389 | |
1390 void | |
1391 ConcurrentMarkSweepGeneration:: | |
1392 par_promote_alloc_undo(int thread_num, | |
1393 HeapWord* obj, size_t word_sz) { | |
1394 // CMS does not support promotion undo. | |
1395 ShouldNotReachHere(); | |
1396 } | |
1397 | |
1398 void | |
1399 ConcurrentMarkSweepGeneration:: | |
1400 par_promote_alloc_done(int thread_num) { | |
1401 CMSParGCThreadState* ps = _par_gc_thread_states[thread_num]; | |
1145
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
1402 ps->lab.retire(thread_num); |
0 | 1403 } |
1404 | |
1405 void | |
1406 ConcurrentMarkSweepGeneration:: | |
1407 par_oop_since_save_marks_iterate_done(int thread_num) { | |
1408 CMSParGCThreadState* ps = _par_gc_thread_states[thread_num]; | |
1409 ParScanWithoutBarrierClosure* dummy_cl = NULL; | |
1410 ps->promo.promoted_oops_iterate_nv(dummy_cl); | |
1411 } | |
1412 | |
1413 // XXXPERM | |
1414 bool ConcurrentMarkSweepGeneration::should_collect(bool full, | |
1415 size_t size, | |
1416 bool tlab) | |
1417 { | |
1418 // We allow a STW collection only if a full | |
1419 // collection was requested. | |
1420 return full || should_allocate(size, tlab); // FIX ME !!! | |
1421 // This and promotion failure handling are connected at the | |
1422 // hip and should be fixed by untying them. | |
1423 } | |
1424 | |
1425 bool CMSCollector::shouldConcurrentCollect() { | |
1426 if (_full_gc_requested) { | |
1427 if (Verbose && PrintGCDetails) { | |
1428 gclog_or_tty->print_cr("CMSCollector: collect because of explicit " | |
1520
bb843ebc7c55
6919638: CMS: ExplicitGCInvokesConcurrent misinteracts with gc locker
ysr
parents:
1518
diff
changeset
|
1429 " gc request (or gc_locker)"); |
0 | 1430 } |
1431 return true; | |
1432 } | |
1433 | |
1434 // For debugging purposes, change the type of collection. | |
1435 // If the rotation is not on the concurrent collection | |
1436 // type, don't start a concurrent collection. | |
1437 NOT_PRODUCT( | |
1438 if (RotateCMSCollectionTypes && | |
1439 (_cmsGen->debug_collection_type() != | |
1440 ConcurrentMarkSweepGeneration::Concurrent_collection_type)) { | |
1441 assert(_cmsGen->debug_collection_type() != | |
1442 ConcurrentMarkSweepGeneration::Unknown_collection_type, | |
1443 "Bad cms collection type"); | |
1444 return false; | |
1445 } | |
1446 ) | |
1447 | |
1448 FreelistLocker x(this); | |
1449 // ------------------------------------------------------------------ | |
1450 // Print out lots of information which affects the initiation of | |
1451 // a collection. | |
1452 if (PrintCMSInitiationStatistics && stats().valid()) { | |
1453 gclog_or_tty->print("CMSCollector shouldConcurrentCollect: "); | |
1454 gclog_or_tty->stamp(); | |
1455 gclog_or_tty->print_cr(""); | |
1456 stats().print_on(gclog_or_tty); | |
1457 gclog_or_tty->print_cr("time_until_cms_gen_full %3.7f", | |
1458 stats().time_until_cms_gen_full()); | |
1459 gclog_or_tty->print_cr("free="SIZE_FORMAT, _cmsGen->free()); | |
1460 gclog_or_tty->print_cr("contiguous_available="SIZE_FORMAT, | |
1461 _cmsGen->contiguous_available()); | |
1462 gclog_or_tty->print_cr("promotion_rate=%g", stats().promotion_rate()); | |
1463 gclog_or_tty->print_cr("cms_allocation_rate=%g", stats().cms_allocation_rate()); | |
1464 gclog_or_tty->print_cr("occupancy=%3.7f", _cmsGen->occupancy()); | |
94
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1465 gclog_or_tty->print_cr("initiatingOccupancy=%3.7f", _cmsGen->initiating_occupancy()); |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1466 gclog_or_tty->print_cr("initiatingPermOccupancy=%3.7f", _permGen->initiating_occupancy()); |
0 | 1467 } |
1468 // ------------------------------------------------------------------ | |
1469 | |
1470 // If the estimated time to complete a cms collection (cms_duration()) | |
1471 // is less than the estimated time remaining until the cms generation | |
1472 // is full, start a collection. | |
1473 if (!UseCMSInitiatingOccupancyOnly) { | |
1474 if (stats().valid()) { | |
1475 if (stats().time_until_cms_start() == 0.0) { | |
1476 return true; | |
1477 } | |
1478 } else { | |
1479 // We want to conservatively collect somewhat early in order | |
1480 // to try and "bootstrap" our CMS/promotion statistics; | |
1481 // this branch will not fire after the first successful CMS | |
1482 // collection because the stats should then be valid. | |
1483 if (_cmsGen->occupancy() >= _bootstrap_occupancy) { | |
1484 if (Verbose && PrintGCDetails) { | |
1485 gclog_or_tty->print_cr( | |
1486 " CMSCollector: collect for bootstrapping statistics:" | |
1487 " occupancy = %f, boot occupancy = %f", _cmsGen->occupancy(), | |
1488 _bootstrap_occupancy); | |
1489 } | |
1490 return true; | |
1491 } | |
1492 } | |
1493 } | |
1494 | |
1495 // Otherwise, we start a collection cycle if either the perm gen or | |
1496 // old gen want a collection cycle started. Each may use | |
1497 // an appropriate criterion for making this decision. | |
1498 // XXX We need to make sure that the gen expansion | |
94
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1499 // criterion dovetails well with this. XXX NEED TO FIX THIS |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1500 if (_cmsGen->should_concurrent_collect()) { |
0 | 1501 if (Verbose && PrintGCDetails) { |
1502 gclog_or_tty->print_cr("CMS old gen initiated"); | |
1503 } | |
1504 return true; | |
1505 } | |
1506 | |
94
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1507 // We start a collection if we believe an incremental collection may fail; |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1508 // this is not likely to be productive in practice because it's probably too |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1509 // late anyway. |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1510 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1511 assert(gch->collector_policy()->is_two_generation_policy(), |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1512 "You may want to check the correctness of the following"); |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1513 if (gch->incremental_collection_will_fail()) { |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1514 if (PrintGCDetails && Verbose) { |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1515 gclog_or_tty->print("CMSCollector: collect because incremental collection will fail "); |
0 | 1516 } |
1517 return true; | |
1518 } | |
1519 | |
94
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1520 if (CMSClassUnloadingEnabled && _permGen->should_concurrent_collect()) { |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1521 bool res = update_should_unload_classes(); |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1522 if (res) { |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1523 if (Verbose && PrintGCDetails) { |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1524 gclog_or_tty->print_cr("CMS perm gen initiated"); |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1525 } |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1526 return true; |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1527 } |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1528 } |
0 | 1529 return false; |
1530 } | |
1531 | |
1532 // Clear _expansion_cause fields of constituent generations | |
1533 void CMSCollector::clear_expansion_cause() { | |
1534 _cmsGen->clear_expansion_cause(); | |
1535 _permGen->clear_expansion_cause(); | |
1536 } | |
1537 | |
94
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1538 // We should be conservative in starting a collection cycle. To |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1539 // start too eagerly runs the risk of collecting too often in the |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1540 // extreme. To collect too rarely falls back on full collections, |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1541 // which works, even if not optimum in terms of concurrent work. |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1542 // As a work around for too eagerly collecting, use the flag |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1543 // UseCMSInitiatingOccupancyOnly. This also has the advantage of |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1544 // giving the user an easily understandable way of controlling the |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1545 // collections. |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1546 // We want to start a new collection cycle if any of the following |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1547 // conditions hold: |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1548 // . our current occupancy exceeds the configured initiating occupancy |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1549 // for this generation, or |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1550 // . we recently needed to expand this space and have not, since that |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1551 // expansion, done a collection of this generation, or |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1552 // . the underlying space believes that it may be a good idea to initiate |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1553 // a concurrent collection (this may be based on criteria such as the |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1554 // following: the space uses linear allocation and linear allocation is |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1555 // going to fail, or there is believed to be excessive fragmentation in |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1556 // the generation, etc... or ... |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1557 // [.(currently done by CMSCollector::shouldConcurrentCollect() only for |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1558 // the case of the old generation, not the perm generation; see CR 6543076): |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1559 // we may be approaching a point at which allocation requests may fail because |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1560 // we will be out of sufficient free space given allocation rate estimates.] |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1561 bool ConcurrentMarkSweepGeneration::should_concurrent_collect() const { |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1562 |
0 | 1563 assert_lock_strong(freelistLock()); |
94
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1564 if (occupancy() > initiating_occupancy()) { |
0 | 1565 if (PrintGCDetails && Verbose) { |
1566 gclog_or_tty->print(" %s: collect because of occupancy %f / %f ", | |
94
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1567 short_name(), occupancy(), initiating_occupancy()); |
0 | 1568 } |
1569 return true; | |
1570 } | |
1571 if (UseCMSInitiatingOccupancyOnly) { | |
1572 return false; | |
1573 } | |
1574 if (expansion_cause() == CMSExpansionCause::_satisfy_allocation) { | |
1575 if (PrintGCDetails && Verbose) { | |
1576 gclog_or_tty->print(" %s: collect because expanded for allocation ", | |
1577 short_name()); | |
1578 } | |
1579 return true; | |
1580 } | |
94
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1581 if (_cmsSpace->should_concurrent_collect()) { |
0 | 1582 if (PrintGCDetails && Verbose) { |
94
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1583 gclog_or_tty->print(" %s: collect because cmsSpace says so ", |
0 | 1584 short_name()); |
1585 } | |
1586 return true; | |
1587 } | |
1588 return false; | |
1589 } | |
1590 | |
1591 void ConcurrentMarkSweepGeneration::collect(bool full, | |
1592 bool clear_all_soft_refs, | |
1593 size_t size, | |
1594 bool tlab) | |
1595 { | |
1596 collector()->collect(full, clear_all_soft_refs, size, tlab); | |
1597 } | |
1598 | |
1599 void CMSCollector::collect(bool full, | |
1600 bool clear_all_soft_refs, | |
1601 size_t size, | |
1602 bool tlab) | |
1603 { | |
1604 if (!UseCMSCollectionPassing && _collectorState > Idling) { | |
1605 // For debugging purposes skip the collection if the state | |
1606 // is not currently idle | |
1607 if (TraceCMSState) { | |
1608 gclog_or_tty->print_cr("Thread " INTPTR_FORMAT " skipped full:%d CMS state %d", | |
1609 Thread::current(), full, _collectorState); | |
1610 } | |
1611 return; | |
1612 } | |
1613 | |
1614 // The following "if" branch is present for defensive reasons. | |
1615 // In the current uses of this interface, it can be replaced with: | |
1616 // assert(!GC_locker.is_active(), "Can't be called otherwise"); | |
1617 // But I am not placing that assert here to allow future | |
1618 // generality in invoking this interface. | |
1619 if (GC_locker::is_active()) { | |
1620 // A consistency test for GC_locker | |
1621 assert(GC_locker::needs_gc(), "Should have been set already"); | |
1622 // Skip this foreground collection, instead | |
1623 // expanding the heap if necessary. | |
1624 // Need the free list locks for the call to free() in compute_new_size() | |
1625 compute_new_size(); | |
1626 return; | |
1627 } | |
1628 acquire_control_and_collect(full, clear_all_soft_refs); | |
1629 _full_gcs_since_conc_gc++; | |
1630 | |
1631 } | |
1632 | |
1633 void CMSCollector::request_full_gc(unsigned int full_gc_count) { | |
1634 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
1635 unsigned int gc_count = gch->total_full_collections(); | |
1636 if (gc_count == full_gc_count) { | |
1637 MutexLockerEx y(CGC_lock, Mutex::_no_safepoint_check_flag); | |
1638 _full_gc_requested = true; | |
1639 CGC_lock->notify(); // nudge CMS thread | |
1640 } | |
1641 } | |
1642 | |
1643 | |
1644 // The foreground and background collectors need to coordinate in order | |
1645 // to make sure that they do not mutually interfere with CMS collections. | |
1646 // When a background collection is active, | |
1647 // the foreground collector may need to take over (preempt) and | |
1648 // synchronously complete an ongoing collection. Depending on the | |
1649 // frequency of the background collections and the heap usage | |
1650 // of the application, this preemption can be seldom or frequent. | |
1651 // There are only certain | |
1652 // points in the background collection that the "collection-baton" | |
1653 // can be passed to the foreground collector. | |
1654 // | |
1655 // The foreground collector will wait for the baton before | |
1656 // starting any part of the collection. The foreground collector | |
1657 // will only wait at one location. | |
1658 // | |
1659 // The background collector will yield the baton before starting a new | |
1660 // phase of the collection (e.g., before initial marking, marking from roots, | |
1661 // precleaning, final re-mark, sweep etc.) This is normally done at the head | |
1662 // of the loop which switches the phases. The background collector does some | |
1663 // of the phases (initial mark, final re-mark) with the world stopped. | |
1664 // Because of locking involved in stopping the world, | |
1665 // the foreground collector should not block waiting for the background | |
1666 // collector when it is doing a stop-the-world phase. The background | |
1667 // collector will yield the baton at an additional point just before | |
1668 // it enters a stop-the-world phase. Once the world is stopped, the | |
1669 // background collector checks the phase of the collection. If the | |
1670 // phase has not changed, it proceeds with the collection. If the | |
1671 // phase has changed, it skips that phase of the collection. See | |
1672 // the comments on the use of the Heap_lock in collect_in_background(). | |
1673 // | |
1674 // Variable used in baton passing. | |
1675 // _foregroundGCIsActive - Set to true by the foreground collector when | |
1676 // it wants the baton. The foreground clears it when it has finished | |
1677 // the collection. | |
1678 // _foregroundGCShouldWait - Set to true by the background collector | |
1679 // when it is running. The foreground collector waits while | |
1680 // _foregroundGCShouldWait is true. | |
1681 // CGC_lock - monitor used to protect access to the above variables | |
1682 // and to notify the foreground and background collectors. | |
1683 // _collectorState - current state of the CMS collection. | |
1684 // | |
1685 // The foreground collector | |
1686 // acquires the CGC_lock | |
1687 // sets _foregroundGCIsActive | |
1688 // waits on the CGC_lock for _foregroundGCShouldWait to be false | |
1689 // various locks acquired in preparation for the collection | |
1690 // are released so as not to block the background collector | |
1691 // that is in the midst of a collection | |
1692 // proceeds with the collection | |
1693 // clears _foregroundGCIsActive | |
1694 // returns | |
1695 // | |
1696 // The background collector in a loop iterating on the phases of the | |
1697 // collection | |
1698 // acquires the CGC_lock | |
1699 // sets _foregroundGCShouldWait | |
1700 // if _foregroundGCIsActive is set | |
1701 // clears _foregroundGCShouldWait, notifies _CGC_lock | |
1702 // waits on _CGC_lock for _foregroundGCIsActive to become false | |
1703 // and exits the loop. | |
1704 // otherwise | |
1705 // proceed with that phase of the collection | |
1706 // if the phase is a stop-the-world phase, | |
1707 // yield the baton once more just before enqueueing | |
1708 // the stop-world CMS operation (executed by the VM thread). | |
1709 // returns after all phases of the collection are done | |
1710 // | |
1711 | |
1712 void CMSCollector::acquire_control_and_collect(bool full, | |
1713 bool clear_all_soft_refs) { | |
1714 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); | |
1715 assert(!Thread::current()->is_ConcurrentGC_thread(), | |
1716 "shouldn't try to acquire control from self!"); | |
1717 | |
1718 // Start the protocol for acquiring control of the | |
1719 // collection from the background collector (aka CMS thread). | |
1720 assert(ConcurrentMarkSweepThread::vm_thread_has_cms_token(), | |
1721 "VM thread should have CMS token"); | |
1722 // Remember the possibly interrupted state of an ongoing | |
1723 // concurrent collection | |
1724 CollectorState first_state = _collectorState; | |
1725 | |
1726 // Signal to a possibly ongoing concurrent collection that | |
1727 // we want to do a foreground collection. | |
1728 _foregroundGCIsActive = true; | |
1729 | |
1730 // Disable incremental mode during a foreground collection. | |
1731 ICMSDisabler icms_disabler; | |
1732 | |
1733 // release locks and wait for a notify from the background collector | |
1734 // releasing the locks in only necessary for phases which | |
1735 // do yields to improve the granularity of the collection. | |
1736 assert_lock_strong(bitMapLock()); | |
1737 // We need to lock the Free list lock for the space that we are | |
1738 // currently collecting. | |
1739 assert(haveFreelistLocks(), "Must be holding free list locks"); | |
1740 bitMapLock()->unlock(); | |
1741 releaseFreelistLocks(); | |
1742 { | |
1743 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
1744 if (_foregroundGCShouldWait) { | |
1745 // We are going to be waiting for action for the CMS thread; | |
1746 // it had better not be gone (for instance at shutdown)! | |
1747 assert(ConcurrentMarkSweepThread::cmst() != NULL, | |
1748 "CMS thread must be running"); | |
1749 // Wait here until the background collector gives us the go-ahead | |
1750 ConcurrentMarkSweepThread::clear_CMS_flag( | |
1751 ConcurrentMarkSweepThread::CMS_vm_has_token); // release token | |
1752 // Get a possibly blocked CMS thread going: | |
1753 // Note that we set _foregroundGCIsActive true above, | |
1754 // without protection of the CGC_lock. | |
1755 CGC_lock->notify(); | |
1756 assert(!ConcurrentMarkSweepThread::vm_thread_wants_cms_token(), | |
1757 "Possible deadlock"); | |
1758 while (_foregroundGCShouldWait) { | |
1759 // wait for notification | |
1760 CGC_lock->wait(Mutex::_no_safepoint_check_flag); | |
1761 // Possibility of delay/starvation here, since CMS token does | |
1762 // not know to give priority to VM thread? Actually, i think | |
1763 // there wouldn't be any delay/starvation, but the proof of | |
1764 // that "fact" (?) appears non-trivial. XXX 20011219YSR | |
1765 } | |
1766 ConcurrentMarkSweepThread::set_CMS_flag( | |
1767 ConcurrentMarkSweepThread::CMS_vm_has_token); | |
1768 } | |
1769 } | |
1770 // The CMS_token is already held. Get back the other locks. | |
1771 assert(ConcurrentMarkSweepThread::vm_thread_has_cms_token(), | |
1772 "VM thread should have CMS token"); | |
1773 getFreelistLocks(); | |
1774 bitMapLock()->lock_without_safepoint_check(); | |
1775 if (TraceCMSState) { | |
1776 gclog_or_tty->print_cr("CMS foreground collector has asked for control " | |
1777 INTPTR_FORMAT " with first state %d", Thread::current(), first_state); | |
1778 gclog_or_tty->print_cr(" gets control with state %d", _collectorState); | |
1779 } | |
1780 | |
1781 // Check if we need to do a compaction, or if not, whether | |
1782 // we need to start the mark-sweep from scratch. | |
1783 bool should_compact = false; | |
1784 bool should_start_over = false; | |
1785 decide_foreground_collection_type(clear_all_soft_refs, | |
1786 &should_compact, &should_start_over); | |
1787 | |
1788 NOT_PRODUCT( | |
1789 if (RotateCMSCollectionTypes) { | |
1790 if (_cmsGen->debug_collection_type() == | |
1791 ConcurrentMarkSweepGeneration::MSC_foreground_collection_type) { | |
1792 should_compact = true; | |
1793 } else if (_cmsGen->debug_collection_type() == | |
1794 ConcurrentMarkSweepGeneration::MS_foreground_collection_type) { | |
1795 should_compact = false; | |
1796 } | |
1797 } | |
1798 ) | |
1799 | |
1800 if (PrintGCDetails && first_state > Idling) { | |
1801 GCCause::Cause cause = GenCollectedHeap::heap()->gc_cause(); | |
1802 if (GCCause::is_user_requested_gc(cause) || | |
1803 GCCause::is_serviceability_requested_gc(cause)) { | |
1804 gclog_or_tty->print(" (concurrent mode interrupted)"); | |
1805 } else { | |
1806 gclog_or_tty->print(" (concurrent mode failure)"); | |
1807 } | |
1808 } | |
1809 | |
1810 if (should_compact) { | |
1811 // If the collection is being acquired from the background | |
1812 // collector, there may be references on the discovered | |
1813 // references lists that have NULL referents (being those | |
1814 // that were concurrently cleared by a mutator) or | |
1815 // that are no longer active (having been enqueued concurrently | |
1816 // by the mutator). | |
1817 // Scrub the list of those references because Mark-Sweep-Compact | |
1818 // code assumes referents are not NULL and that all discovered | |
1819 // Reference objects are active. | |
1820 ref_processor()->clean_up_discovered_references(); | |
1821 | |
1822 do_compaction_work(clear_all_soft_refs); | |
1823 | |
1824 // Has the GC time limit been exceeded? | |
1387
0bfd3fb24150
6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
jmasa
parents:
1289
diff
changeset
|
1825 DefNewGeneration* young_gen = _young_gen->as_DefNewGeneration(); |
0bfd3fb24150
6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
jmasa
parents:
1289
diff
changeset
|
1826 size_t max_eden_size = young_gen->max_capacity() - |
0bfd3fb24150
6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
jmasa
parents:
1289
diff
changeset
|
1827 young_gen->to()->capacity() - |
0bfd3fb24150
6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
jmasa
parents:
1289
diff
changeset
|
1828 young_gen->from()->capacity(); |
0bfd3fb24150
6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
jmasa
parents:
1289
diff
changeset
|
1829 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
0bfd3fb24150
6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
jmasa
parents:
1289
diff
changeset
|
1830 GCCause::Cause gc_cause = gch->gc_cause(); |
0bfd3fb24150
6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
jmasa
parents:
1289
diff
changeset
|
1831 size_policy()->check_gc_overhead_limit(_young_gen->used(), |
0bfd3fb24150
6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
jmasa
parents:
1289
diff
changeset
|
1832 young_gen->eden()->used(), |
0bfd3fb24150
6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
jmasa
parents:
1289
diff
changeset
|
1833 _cmsGen->max_capacity(), |
0bfd3fb24150
6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
jmasa
parents:
1289
diff
changeset
|
1834 max_eden_size, |
0bfd3fb24150
6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
jmasa
parents:
1289
diff
changeset
|
1835 full, |
0bfd3fb24150
6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
jmasa
parents:
1289
diff
changeset
|
1836 gc_cause, |
0bfd3fb24150
6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
jmasa
parents:
1289
diff
changeset
|
1837 gch->collector_policy()); |
0 | 1838 } else { |
1839 do_mark_sweep_work(clear_all_soft_refs, first_state, | |
1840 should_start_over); | |
1841 } | |
1842 // Reset the expansion cause, now that we just completed | |
1843 // a collection cycle. | |
1844 clear_expansion_cause(); | |
1845 _foregroundGCIsActive = false; | |
1846 return; | |
1847 } | |
1848 | |
1849 // Resize the perm generation and the tenured generation | |
1850 // after obtaining the free list locks for the | |
1851 // two generations. | |
1852 void CMSCollector::compute_new_size() { | |
1853 assert_locked_or_safepoint(Heap_lock); | |
1854 FreelistLocker z(this); | |
1855 _permGen->compute_new_size(); | |
1856 _cmsGen->compute_new_size(); | |
1857 } | |
1858 | |
1859 // A work method used by foreground collection to determine | |
1860 // what type of collection (compacting or not, continuing or fresh) | |
1861 // it should do. | |
1862 // NOTE: the intent is to make UseCMSCompactAtFullCollection | |
1863 // and CMSCompactWhenClearAllSoftRefs the default in the future | |
1864 // and do away with the flags after a suitable period. | |
1865 void CMSCollector::decide_foreground_collection_type( | |
1866 bool clear_all_soft_refs, bool* should_compact, | |
1867 bool* should_start_over) { | |
1868 // Normally, we'll compact only if the UseCMSCompactAtFullCollection | |
1869 // flag is set, and we have either requested a System.gc() or | |
1870 // the number of full gc's since the last concurrent cycle | |
1871 // has exceeded the threshold set by CMSFullGCsBeforeCompaction, | |
1872 // or if an incremental collection has failed | |
1873 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
1874 assert(gch->collector_policy()->is_two_generation_policy(), | |
1875 "You may want to check the correctness of the following"); | |
1876 // Inform cms gen if this was due to partial collection failing. | |
1877 // The CMS gen may use this fact to determine its expansion policy. | |
1878 if (gch->incremental_collection_will_fail()) { | |
1879 assert(!_cmsGen->incremental_collection_failed(), | |
1880 "Should have been noticed, reacted to and cleared"); | |
1881 _cmsGen->set_incremental_collection_failed(); | |
1882 } | |
1883 *should_compact = | |
1884 UseCMSCompactAtFullCollection && | |
1885 ((_full_gcs_since_conc_gc >= CMSFullGCsBeforeCompaction) || | |
1886 GCCause::is_user_requested_gc(gch->gc_cause()) || | |
1887 gch->incremental_collection_will_fail()); | |
1888 *should_start_over = false; | |
1889 if (clear_all_soft_refs && !*should_compact) { | |
1890 // We are about to do a last ditch collection attempt | |
1891 // so it would normally make sense to do a compaction | |
1892 // to reclaim as much space as possible. | |
1893 if (CMSCompactWhenClearAllSoftRefs) { | |
1894 // Default: The rationale is that in this case either | |
1895 // we are past the final marking phase, in which case | |
1896 // we'd have to start over, or so little has been done | |
1897 // that there's little point in saving that work. Compaction | |
1898 // appears to be the sensible choice in either case. | |
1899 *should_compact = true; | |
1900 } else { | |
1901 // We have been asked to clear all soft refs, but not to | |
1902 // compact. Make sure that we aren't past the final checkpoint | |
1903 // phase, for that is where we process soft refs. If we are already | |
1904 // past that phase, we'll need to redo the refs discovery phase and | |
1905 // if necessary clear soft refs that weren't previously | |
1906 // cleared. We do so by remembering the phase in which | |
1907 // we came in, and if we are past the refs processing | |
1908 // phase, we'll choose to just redo the mark-sweep | |
1909 // collection from scratch. | |
1910 if (_collectorState > FinalMarking) { | |
1911 // We are past the refs processing phase; | |
1912 // start over and do a fresh synchronous CMS cycle | |
1913 _collectorState = Resetting; // skip to reset to start new cycle | |
1914 reset(false /* == !asynch */); | |
1915 *should_start_over = true; | |
1916 } // else we can continue a possibly ongoing current cycle | |
1917 } | |
1918 } | |
1919 } | |
1920 | |
1921 // A work method used by the foreground collector to do | |
1922 // a mark-sweep-compact. | |
1923 void CMSCollector::do_compaction_work(bool clear_all_soft_refs) { | |
1924 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
1925 TraceTime t("CMS:MSC ", PrintGCDetails && Verbose, true, gclog_or_tty); | |
1926 if (PrintGC && Verbose && !(GCCause::is_user_requested_gc(gch->gc_cause()))) { | |
1927 gclog_or_tty->print_cr("Compact ConcurrentMarkSweepGeneration after %d " | |
1928 "collections passed to foreground collector", _full_gcs_since_conc_gc); | |
1929 } | |
1930 | |
1931 // Sample collection interval time and reset for collection pause. | |
1932 if (UseAdaptiveSizePolicy) { | |
1933 size_policy()->msc_collection_begin(); | |
1934 } | |
1935 | |
1936 // Temporarily widen the span of the weak reference processing to | |
1937 // the entire heap. | |
1938 MemRegion new_span(GenCollectedHeap::heap()->reserved_region()); | |
1939 ReferenceProcessorSpanMutator x(ref_processor(), new_span); | |
1940 | |
1941 // Temporarily, clear the "is_alive_non_header" field of the | |
1942 // reference processor. | |
1943 ReferenceProcessorIsAliveMutator y(ref_processor(), NULL); | |
1944 | |
1945 // Temporarily make reference _processing_ single threaded (non-MT). | |
1946 ReferenceProcessorMTProcMutator z(ref_processor(), false); | |
1947 | |
1948 // Temporarily make refs discovery atomic | |
1949 ReferenceProcessorAtomicMutator w(ref_processor(), true); | |
1950 | |
1951 ref_processor()->set_enqueuing_is_done(false); | |
1952 ref_processor()->enable_discovery(); | |
457
27a80744a83b
6778647: snap(), snap_policy() should be renamed setup(), setup_policy()
ysr
parents:
453
diff
changeset
|
1953 ref_processor()->setup_policy(clear_all_soft_refs); |
0 | 1954 // If an asynchronous collection finishes, the _modUnionTable is |
1955 // all clear. If we are assuming the collection from an asynchronous | |
1956 // collection, clear the _modUnionTable. | |
1957 assert(_collectorState != Idling || _modUnionTable.isAllClear(), | |
1958 "_modUnionTable should be clear if the baton was not passed"); | |
1959 _modUnionTable.clear_all(); | |
1960 | |
1961 // We must adjust the allocation statistics being maintained | |
1962 // in the free list space. We do so by reading and clearing | |
1963 // the sweep timer and updating the block flux rate estimates below. | |
1145
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
1964 assert(!_intra_sweep_timer.is_active(), "_intra_sweep_timer should be inactive"); |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
1965 if (_inter_sweep_timer.is_active()) { |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
1966 _inter_sweep_timer.stop(); |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
1967 // Note that we do not use this sample to update the _inter_sweep_estimate. |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
1968 _cmsGen->cmsSpace()->beginSweepFLCensus((float)(_inter_sweep_timer.seconds()), |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
1969 _inter_sweep_estimate.padded_average(), |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
1970 _intra_sweep_estimate.padded_average()); |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
1971 } |
0 | 1972 |
1973 GenMarkSweep::invoke_at_safepoint(_cmsGen->level(), | |
1974 ref_processor(), clear_all_soft_refs); | |
1975 #ifdef ASSERT | |
1976 CompactibleFreeListSpace* cms_space = _cmsGen->cmsSpace(); | |
1977 size_t free_size = cms_space->free(); | |
1978 assert(free_size == | |
1979 pointer_delta(cms_space->end(), cms_space->compaction_top()) | |
1980 * HeapWordSize, | |
1981 "All the free space should be compacted into one chunk at top"); | |
1982 assert(cms_space->dictionary()->totalChunkSize( | |
1983 debug_only(cms_space->freelistLock())) == 0 || | |
1984 cms_space->totalSizeInIndexedFreeLists() == 0, | |
1985 "All the free space should be in a single chunk"); | |
1986 size_t num = cms_space->totalCount(); | |
1987 assert((free_size == 0 && num == 0) || | |
1988 (free_size > 0 && (num == 1 || num == 2)), | |
1989 "There should be at most 2 free chunks after compaction"); | |
1990 #endif // ASSERT | |
1991 _collectorState = Resetting; | |
1992 assert(_restart_addr == NULL, | |
1993 "Should have been NULL'd before baton was passed"); | |
1994 reset(false /* == !asynch */); | |
1995 _cmsGen->reset_after_compaction(); | |
94
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1996 _concurrent_cycles_since_last_unload = 0; |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1997 |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
1998 if (verifying() && !should_unload_classes()) { |
0 | 1999 perm_gen_verify_bit_map()->clear_all(); |
2000 } | |
2001 | |
2002 // Clear any data recorded in the PLAB chunk arrays. | |
2003 if (_survivor_plab_array != NULL) { | |
2004 reset_survivor_plab_arrays(); | |
2005 } | |
2006 | |
2007 // Adjust the per-size allocation stats for the next epoch. | |
1145
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
2008 _cmsGen->cmsSpace()->endSweepFLCensus(sweep_count() /* fake */); |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
2009 // Restart the "inter sweep timer" for the next epoch. |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
2010 _inter_sweep_timer.reset(); |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
2011 _inter_sweep_timer.start(); |
0 | 2012 |
2013 // Sample collection pause time and reset for collection interval. | |
2014 if (UseAdaptiveSizePolicy) { | |
2015 size_policy()->msc_collection_end(gch->gc_cause()); | |
2016 } | |
2017 | |
2018 // For a mark-sweep-compact, compute_new_size() will be called | |
2019 // in the heap's do_collection() method. | |
2020 } | |
2021 | |
2022 // A work method used by the foreground collector to do | |
2023 // a mark-sweep, after taking over from a possibly on-going | |
2024 // concurrent mark-sweep collection. | |
2025 void CMSCollector::do_mark_sweep_work(bool clear_all_soft_refs, | |
2026 CollectorState first_state, bool should_start_over) { | |
2027 if (PrintGC && Verbose) { | |
2028 gclog_or_tty->print_cr("Pass concurrent collection to foreground " | |
2029 "collector with count %d", | |
2030 _full_gcs_since_conc_gc); | |
2031 } | |
2032 switch (_collectorState) { | |
2033 case Idling: | |
2034 if (first_state == Idling || should_start_over) { | |
2035 // The background GC was not active, or should | |
2036 // restarted from scratch; start the cycle. | |
2037 _collectorState = InitialMarking; | |
2038 } | |
2039 // If first_state was not Idling, then a background GC | |
2040 // was in progress and has now finished. No need to do it | |
2041 // again. Leave the state as Idling. | |
2042 break; | |
2043 case Precleaning: | |
2044 // In the foreground case don't do the precleaning since | |
2045 // it is not done concurrently and there is extra work | |
2046 // required. | |
2047 _collectorState = FinalMarking; | |
2048 } | |
2049 if (PrintGCDetails && | |
2050 (_collectorState > Idling || | |
2051 !GCCause::is_user_requested_gc(GenCollectedHeap::heap()->gc_cause()))) { | |
2052 gclog_or_tty->print(" (concurrent mode failure)"); | |
2053 } | |
2054 collect_in_foreground(clear_all_soft_refs); | |
2055 | |
2056 // For a mark-sweep, compute_new_size() will be called | |
2057 // in the heap's do_collection() method. | |
2058 } | |
2059 | |
2060 | |
2061 void CMSCollector::getFreelistLocks() const { | |
2062 // Get locks for all free lists in all generations that this | |
2063 // collector is responsible for | |
2064 _cmsGen->freelistLock()->lock_without_safepoint_check(); | |
2065 _permGen->freelistLock()->lock_without_safepoint_check(); | |
2066 } | |
2067 | |
2068 void CMSCollector::releaseFreelistLocks() const { | |
2069 // Release locks for all free lists in all generations that this | |
2070 // collector is responsible for | |
2071 _cmsGen->freelistLock()->unlock(); | |
2072 _permGen->freelistLock()->unlock(); | |
2073 } | |
2074 | |
2075 bool CMSCollector::haveFreelistLocks() const { | |
2076 // Check locks for all free lists in all generations that this | |
2077 // collector is responsible for | |
2078 assert_lock_strong(_cmsGen->freelistLock()); | |
2079 assert_lock_strong(_permGen->freelistLock()); | |
2080 PRODUCT_ONLY(ShouldNotReachHere()); | |
2081 return true; | |
2082 } | |
2083 | |
2084 // A utility class that is used by the CMS collector to | |
2085 // temporarily "release" the foreground collector from its | |
2086 // usual obligation to wait for the background collector to | |
2087 // complete an ongoing phase before proceeding. | |
2088 class ReleaseForegroundGC: public StackObj { | |
2089 private: | |
2090 CMSCollector* _c; | |
2091 public: | |
2092 ReleaseForegroundGC(CMSCollector* c) : _c(c) { | |
2093 assert(_c->_foregroundGCShouldWait, "Else should not need to call"); | |
2094 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
2095 // allow a potentially blocked foreground collector to proceed | |
2096 _c->_foregroundGCShouldWait = false; | |
2097 if (_c->_foregroundGCIsActive) { | |
2098 CGC_lock->notify(); | |
2099 } | |
2100 assert(!ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
2101 "Possible deadlock"); | |
2102 } | |
2103 | |
2104 ~ReleaseForegroundGC() { | |
2105 assert(!_c->_foregroundGCShouldWait, "Usage protocol violation?"); | |
2106 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
2107 _c->_foregroundGCShouldWait = true; | |
2108 } | |
2109 }; | |
2110 | |
2111 // There are separate collect_in_background and collect_in_foreground because of | |
2112 // the different locking requirements of the background collector and the | |
2113 // foreground collector. There was originally an attempt to share | |
2114 // one "collect" method between the background collector and the foreground | |
2115 // collector but the if-then-else required made it cleaner to have | |
2116 // separate methods. | |
2117 void CMSCollector::collect_in_background(bool clear_all_soft_refs) { | |
2118 assert(Thread::current()->is_ConcurrentGC_thread(), | |
2119 "A CMS asynchronous collection is only allowed on a CMS thread."); | |
2120 | |
2121 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
2122 { | |
2123 bool safepoint_check = Mutex::_no_safepoint_check_flag; | |
2124 MutexLockerEx hl(Heap_lock, safepoint_check); | |
94
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
2125 FreelistLocker fll(this); |
0 | 2126 MutexLockerEx x(CGC_lock, safepoint_check); |
2127 if (_foregroundGCIsActive || !UseAsyncConcMarkSweepGC) { | |
2128 // The foreground collector is active or we're | |
2129 // not using asynchronous collections. Skip this | |
2130 // background collection. | |
2131 assert(!_foregroundGCShouldWait, "Should be clear"); | |
2132 return; | |
2133 } else { | |
2134 assert(_collectorState == Idling, "Should be idling before start."); | |
2135 _collectorState = InitialMarking; | |
2136 // Reset the expansion cause, now that we are about to begin | |
2137 // a new cycle. | |
2138 clear_expansion_cause(); | |
2139 } | |
94
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
2140 // Decide if we want to enable class unloading as part of the |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
2141 // ensuing concurrent GC cycle. |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
2142 update_should_unload_classes(); |
0 | 2143 _full_gc_requested = false; // acks all outstanding full gc requests |
2144 // Signal that we are about to start a collection | |
2145 gch->increment_total_full_collections(); // ... starting a collection cycle | |
2146 _collection_count_start = gch->total_full_collections(); | |
2147 } | |
2148 | |
2149 // Used for PrintGC | |
2150 size_t prev_used; | |
2151 if (PrintGC && Verbose) { | |
2152 prev_used = _cmsGen->used(); // XXXPERM | |
2153 } | |
2154 | |
2155 // The change of the collection state is normally done at this level; | |
2156 // the exceptions are phases that are executed while the world is | |
2157 // stopped. For those phases the change of state is done while the | |
2158 // world is stopped. For baton passing purposes this allows the | |
2159 // background collector to finish the phase and change state atomically. | |
2160 // The foreground collector cannot wait on a phase that is done | |
2161 // while the world is stopped because the foreground collector already | |
2162 // has the world stopped and would deadlock. | |
2163 while (_collectorState != Idling) { | |
2164 if (TraceCMSState) { | |
2165 gclog_or_tty->print_cr("Thread " INTPTR_FORMAT " in CMS state %d", | |
2166 Thread::current(), _collectorState); | |
2167 } | |
2168 // The foreground collector | |
2169 // holds the Heap_lock throughout its collection. | |
2170 // holds the CMS token (but not the lock) | |
2171 // except while it is waiting for the background collector to yield. | |
2172 // | |
2173 // The foreground collector should be blocked (not for long) | |
2174 // if the background collector is about to start a phase | |
2175 // executed with world stopped. If the background | |
2176 // collector has already started such a phase, the | |
2177 // foreground collector is blocked waiting for the | |
2178 // Heap_lock. The stop-world phases (InitialMarking and FinalMarking) | |
2179 // are executed in the VM thread. | |
2180 // | |
2181 // The locking order is | |
2182 // PendingListLock (PLL) -- if applicable (FinalMarking) | |
2183 // Heap_lock (both this & PLL locked in VM_CMS_Operation::prologue()) | |
2184 // CMS token (claimed in | |
2185 // stop_world_and_do() --> | |
2186 // safepoint_synchronize() --> | |
2187 // CMSThread::synchronize()) | |
2188 | |
2189 { | |
2190 // Check if the FG collector wants us to yield. | |
2191 CMSTokenSync x(true); // is cms thread | |
2192 if (waitForForegroundGC()) { | |
2193 // We yielded to a foreground GC, nothing more to be | |
2194 // done this round. | |
2195 assert(_foregroundGCShouldWait == false, "We set it to false in " | |
2196 "waitForForegroundGC()"); | |
2197 if (TraceCMSState) { | |
2198 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT | |
2199 " exiting collection CMS state %d", | |
2200 Thread::current(), _collectorState); | |
2201 } | |
2202 return; | |
2203 } else { | |
2204 // The background collector can run but check to see if the | |
2205 // foreground collector has done a collection while the | |
2206 // background collector was waiting to get the CGC_lock | |
2207 // above. If yes, break so that _foregroundGCShouldWait | |
2208 // is cleared before returning. | |
2209 if (_collectorState == Idling) { | |
2210 break; | |
2211 } | |
2212 } | |
2213 } | |
2214 | |
2215 assert(_foregroundGCShouldWait, "Foreground collector, if active, " | |
2216 "should be waiting"); | |
2217 | |
2218 switch (_collectorState) { | |
2219 case InitialMarking: | |
2220 { | |
2221 ReleaseForegroundGC x(this); | |
2222 stats().record_cms_begin(); | |
2223 | |
2224 VM_CMS_Initial_Mark initial_mark_op(this); | |
2225 VMThread::execute(&initial_mark_op); | |
2226 } | |
2227 // The collector state may be any legal state at this point | |
2228 // since the background collector may have yielded to the | |
2229 // foreground collector. | |
2230 break; | |
2231 case Marking: | |
2232 // initial marking in checkpointRootsInitialWork has been completed | |
2233 if (markFromRoots(true)) { // we were successful | |
2234 assert(_collectorState == Precleaning, "Collector state should " | |
2235 "have changed"); | |
2236 } else { | |
2237 assert(_foregroundGCIsActive, "Internal state inconsistency"); | |
2238 } | |
2239 break; | |
2240 case Precleaning: | |
2241 if (UseAdaptiveSizePolicy) { | |
2242 size_policy()->concurrent_precleaning_begin(); | |
2243 } | |
2244 // marking from roots in markFromRoots has been completed | |
2245 preclean(); | |
2246 if (UseAdaptiveSizePolicy) { | |
2247 size_policy()->concurrent_precleaning_end(); | |
2248 } | |
2249 assert(_collectorState == AbortablePreclean || | |
2250 _collectorState == FinalMarking, | |
2251 "Collector state should have changed"); | |
2252 break; | |
2253 case AbortablePreclean: | |
2254 if (UseAdaptiveSizePolicy) { | |
2255 size_policy()->concurrent_phases_resume(); | |
2256 } | |
2257 abortable_preclean(); | |
2258 if (UseAdaptiveSizePolicy) { | |
2259 size_policy()->concurrent_precleaning_end(); | |
2260 } | |
2261 assert(_collectorState == FinalMarking, "Collector state should " | |
2262 "have changed"); | |
2263 break; | |
2264 case FinalMarking: | |
2265 { | |
2266 ReleaseForegroundGC x(this); | |
2267 | |
2268 VM_CMS_Final_Remark final_remark_op(this); | |
2269 VMThread::execute(&final_remark_op); | |
935 | 2270 } |
0 | 2271 assert(_foregroundGCShouldWait, "block post-condition"); |
2272 break; | |
2273 case Sweeping: | |
2274 if (UseAdaptiveSizePolicy) { | |
2275 size_policy()->concurrent_sweeping_begin(); | |
2276 } | |
2277 // final marking in checkpointRootsFinal has been completed | |
2278 sweep(true); | |
2279 assert(_collectorState == Resizing, "Collector state change " | |
2280 "to Resizing must be done under the free_list_lock"); | |
2281 _full_gcs_since_conc_gc = 0; | |
2282 | |
2283 // Stop the timers for adaptive size policy for the concurrent phases | |
2284 if (UseAdaptiveSizePolicy) { | |
2285 size_policy()->concurrent_sweeping_end(); | |
2286 size_policy()->concurrent_phases_end(gch->gc_cause(), | |
2287 gch->prev_gen(_cmsGen)->capacity(), | |
2288 _cmsGen->free()); | |
2289 } | |
2290 | |
2291 case Resizing: { | |
2292 // Sweeping has been completed... | |
2293 // At this point the background collection has completed. | |
2294 // Don't move the call to compute_new_size() down | |
2295 // into code that might be executed if the background | |
2296 // collection was preempted. | |
2297 { | |
2298 ReleaseForegroundGC x(this); // unblock FG collection | |
2299 MutexLockerEx y(Heap_lock, Mutex::_no_safepoint_check_flag); | |
2300 CMSTokenSync z(true); // not strictly needed. | |
2301 if (_collectorState == Resizing) { | |
2302 compute_new_size(); | |
2303 _collectorState = Resetting; | |
2304 } else { | |
2305 assert(_collectorState == Idling, "The state should only change" | |
2306 " because the foreground collector has finished the collection"); | |
2307 } | |
2308 } | |
2309 break; | |
2310 } | |
2311 case Resetting: | |
2312 // CMS heap resizing has been completed | |
2313 reset(true); | |
2314 assert(_collectorState == Idling, "Collector state should " | |
2315 "have changed"); | |
2316 stats().record_cms_end(); | |
2317 // Don't move the concurrent_phases_end() and compute_new_size() | |
2318 // calls to here because a preempted background collection | |
2319 // has it's state set to "Resetting". | |
2320 break; | |
2321 case Idling: | |
2322 default: | |
2323 ShouldNotReachHere(); | |
2324 break; | |
2325 } | |
2326 if (TraceCMSState) { | |
2327 gclog_or_tty->print_cr(" Thread " INTPTR_FORMAT " done - next CMS state %d", | |
2328 Thread::current(), _collectorState); | |
2329 } | |
2330 assert(_foregroundGCShouldWait, "block post-condition"); | |
2331 } | |
2332 | |
2333 // Should this be in gc_epilogue? | |
2334 collector_policy()->counters()->update_counters(); | |
2335 | |
2336 { | |
2337 // Clear _foregroundGCShouldWait and, in the event that the | |
2338 // foreground collector is waiting, notify it, before | |
2339 // returning. | |
2340 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
2341 _foregroundGCShouldWait = false; | |
2342 if (_foregroundGCIsActive) { | |
2343 CGC_lock->notify(); | |
2344 } | |
2345 assert(!ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
2346 "Possible deadlock"); | |
2347 } | |
2348 if (TraceCMSState) { | |
2349 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT | |
2350 " exiting collection CMS state %d", | |
2351 Thread::current(), _collectorState); | |
2352 } | |
2353 if (PrintGC && Verbose) { | |
2354 _cmsGen->print_heap_change(prev_used); | |
2355 } | |
2356 } | |
2357 | |
2358 void CMSCollector::collect_in_foreground(bool clear_all_soft_refs) { | |
2359 assert(_foregroundGCIsActive && !_foregroundGCShouldWait, | |
2360 "Foreground collector should be waiting, not executing"); | |
2361 assert(Thread::current()->is_VM_thread(), "A foreground collection" | |
2362 "may only be done by the VM Thread with the world stopped"); | |
2363 assert(ConcurrentMarkSweepThread::vm_thread_has_cms_token(), | |
2364 "VM thread should have CMS token"); | |
2365 | |
2366 NOT_PRODUCT(TraceTime t("CMS:MS (foreground) ", PrintGCDetails && Verbose, | |
2367 true, gclog_or_tty);) | |
2368 if (UseAdaptiveSizePolicy) { | |
2369 size_policy()->ms_collection_begin(); | |
2370 } | |
2371 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact); | |
2372 | |
2373 HandleMark hm; // Discard invalid handles created during verification | |
2374 | |
2375 if (VerifyBeforeGC && | |
2376 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
2377 Universe::verify(true); | |
2378 } | |
2379 | |
453
c96030fff130
6684579: SoftReference processing can be made more efficient
ysr
parents:
452
diff
changeset
|
2380 // Snapshot the soft reference policy to be used in this collection cycle. |
457
27a80744a83b
6778647: snap(), snap_policy() should be renamed setup(), setup_policy()
ysr
parents:
453
diff
changeset
|
2381 ref_processor()->setup_policy(clear_all_soft_refs); |
453
c96030fff130
6684579: SoftReference processing can be made more efficient
ysr
parents:
452
diff
changeset
|
2382 |
0 | 2383 bool init_mark_was_synchronous = false; // until proven otherwise |
2384 while (_collectorState != Idling) { | |
2385 if (TraceCMSState) { | |
2386 gclog_or_tty->print_cr("Thread " INTPTR_FORMAT " in CMS state %d", | |
2387 Thread::current(), _collectorState); | |
2388 } | |
2389 switch (_collectorState) { | |
2390 case InitialMarking: | |
2391 init_mark_was_synchronous = true; // fact to be exploited in re-mark | |
2392 checkpointRootsInitial(false); | |
2393 assert(_collectorState == Marking, "Collector state should have changed" | |
2394 " within checkpointRootsInitial()"); | |
2395 break; | |
2396 case Marking: | |
2397 // initial marking in checkpointRootsInitialWork has been completed | |
2398 if (VerifyDuringGC && | |
2399 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
2400 gclog_or_tty->print("Verify before initial mark: "); | |
2401 Universe::verify(true); | |
2402 } | |
2403 { | |
2404 bool res = markFromRoots(false); | |
2405 assert(res && _collectorState == FinalMarking, "Collector state should " | |
2406 "have changed"); | |
2407 break; | |
2408 } | |
2409 case FinalMarking: | |
2410 if (VerifyDuringGC && | |
2411 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
2412 gclog_or_tty->print("Verify before re-mark: "); | |
2413 Universe::verify(true); | |
2414 } | |
2415 checkpointRootsFinal(false, clear_all_soft_refs, | |
2416 init_mark_was_synchronous); | |
2417 assert(_collectorState == Sweeping, "Collector state should not " | |
2418 "have changed within checkpointRootsFinal()"); | |
2419 break; | |
2420 case Sweeping: | |
2421 // final marking in checkpointRootsFinal has been completed | |
2422 if (VerifyDuringGC && | |
2423 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
2424 gclog_or_tty->print("Verify before sweep: "); | |
2425 Universe::verify(true); | |
2426 } | |
2427 sweep(false); | |
2428 assert(_collectorState == Resizing, "Incorrect state"); | |
2429 break; | |
2430 case Resizing: { | |
2431 // Sweeping has been completed; the actual resize in this case | |
2432 // is done separately; nothing to be done in this state. | |
2433 _collectorState = Resetting; | |
2434 break; | |
2435 } | |
2436 case Resetting: | |
2437 // The heap has been resized. | |
2438 if (VerifyDuringGC && | |
2439 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
2440 gclog_or_tty->print("Verify before reset: "); | |
2441 Universe::verify(true); | |
2442 } | |
2443 reset(false); | |
2444 assert(_collectorState == Idling, "Collector state should " | |
2445 "have changed"); | |
2446 break; | |
2447 case Precleaning: | |
2448 case AbortablePreclean: | |
2449 // Elide the preclean phase | |
2450 _collectorState = FinalMarking; | |
2451 break; | |
2452 default: | |
2453 ShouldNotReachHere(); | |
2454 } | |
2455 if (TraceCMSState) { | |
2456 gclog_or_tty->print_cr(" Thread " INTPTR_FORMAT " done - next CMS state %d", | |
2457 Thread::current(), _collectorState); | |
2458 } | |
2459 } | |
2460 | |
2461 if (UseAdaptiveSizePolicy) { | |
2462 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
2463 size_policy()->ms_collection_end(gch->gc_cause()); | |
2464 } | |
2465 | |
2466 if (VerifyAfterGC && | |
2467 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
2468 Universe::verify(true); | |
2469 } | |
2470 if (TraceCMSState) { | |
2471 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT | |
2472 " exiting collection CMS state %d", | |
2473 Thread::current(), _collectorState); | |
2474 } | |
2475 } | |
2476 | |
2477 bool CMSCollector::waitForForegroundGC() { | |
2478 bool res = false; | |
2479 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
2480 "CMS thread should have CMS token"); | |
2481 // Block the foreground collector until the | |
2482 // background collectors decides whether to | |
2483 // yield. | |
2484 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); | |
2485 _foregroundGCShouldWait = true; | |
2486 if (_foregroundGCIsActive) { | |
2487 // The background collector yields to the | |
2488 // foreground collector and returns a value | |
2489 // indicating that it has yielded. The foreground | |
2490 // collector can proceed. | |
2491 res = true; | |
2492 _foregroundGCShouldWait = false; | |
2493 ConcurrentMarkSweepThread::clear_CMS_flag( | |
2494 ConcurrentMarkSweepThread::CMS_cms_has_token); | |
2495 ConcurrentMarkSweepThread::set_CMS_flag( | |
2496 ConcurrentMarkSweepThread::CMS_cms_wants_token); | |
2497 // Get a possibly blocked foreground thread going | |
2498 CGC_lock->notify(); | |
2499 if (TraceCMSState) { | |
2500 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT " waiting at CMS state %d", | |
2501 Thread::current(), _collectorState); | |
2502 } | |
2503 while (_foregroundGCIsActive) { | |
2504 CGC_lock->wait(Mutex::_no_safepoint_check_flag); | |
2505 } | |
2506 ConcurrentMarkSweepThread::set_CMS_flag( | |
2507 ConcurrentMarkSweepThread::CMS_cms_has_token); | |
2508 ConcurrentMarkSweepThread::clear_CMS_flag( | |
2509 ConcurrentMarkSweepThread::CMS_cms_wants_token); | |
2510 } | |
2511 if (TraceCMSState) { | |
2512 gclog_or_tty->print_cr("CMS Thread " INTPTR_FORMAT " continuing at CMS state %d", | |
2513 Thread::current(), _collectorState); | |
2514 } | |
2515 return res; | |
2516 } | |
2517 | |
2518 // Because of the need to lock the free lists and other structures in | |
2519 // the collector, common to all the generations that the collector is | |
2520 // collecting, we need the gc_prologues of individual CMS generations | |
2521 // delegate to their collector. It may have been simpler had the | |
2522 // current infrastructure allowed one to call a prologue on a | |
2523 // collector. In the absence of that we have the generation's | |
2524 // prologue delegate to the collector, which delegates back | |
2525 // some "local" work to a worker method in the individual generations | |
2526 // that it's responsible for collecting, while itself doing any | |
2527 // work common to all generations it's responsible for. A similar | |
2528 // comment applies to the gc_epilogue()'s. | |
2529 // The role of the varaible _between_prologue_and_epilogue is to | |
2530 // enforce the invocation protocol. | |
2531 void CMSCollector::gc_prologue(bool full) { | |
2532 // Call gc_prologue_work() for each CMSGen and PermGen that | |
2533 // we are responsible for. | |
2534 | |
2535 // The following locking discipline assumes that we are only called | |
2536 // when the world is stopped. | |
2537 assert(SafepointSynchronize::is_at_safepoint(), "world is stopped assumption"); | |
2538 | |
2539 // The CMSCollector prologue must call the gc_prologues for the | |
2540 // "generations" (including PermGen if any) that it's responsible | |
2541 // for. | |
2542 | |
2543 assert( Thread::current()->is_VM_thread() | |
2544 || ( CMSScavengeBeforeRemark | |
2545 && Thread::current()->is_ConcurrentGC_thread()), | |
2546 "Incorrect thread type for prologue execution"); | |
2547 | |
2548 if (_between_prologue_and_epilogue) { | |
2549 // We have already been invoked; this is a gc_prologue delegation | |
2550 // from yet another CMS generation that we are responsible for, just | |
2551 // ignore it since all relevant work has already been done. | |
2552 return; | |
2553 } | |
2554 | |
2555 // set a bit saying prologue has been called; cleared in epilogue | |
2556 _between_prologue_and_epilogue = true; | |
2557 // Claim locks for common data structures, then call gc_prologue_work() | |
2558 // for each CMSGen and PermGen that we are responsible for. | |
2559 | |
2560 getFreelistLocks(); // gets free list locks on constituent spaces | |
2561 bitMapLock()->lock_without_safepoint_check(); | |
2562 | |
2563 // Should call gc_prologue_work() for all cms gens we are responsible for | |
2564 bool registerClosure = _collectorState >= Marking | |
2565 && _collectorState < Sweeping; | |
2566 ModUnionClosure* muc = ParallelGCThreads > 0 ? &_modUnionClosurePar | |
2567 : &_modUnionClosure; | |
2568 _cmsGen->gc_prologue_work(full, registerClosure, muc); | |
2569 _permGen->gc_prologue_work(full, registerClosure, muc); | |
2570 | |
2571 if (!full) { | |
2572 stats().record_gc0_begin(); | |
2573 } | |
2574 } | |
2575 | |
2576 void ConcurrentMarkSweepGeneration::gc_prologue(bool full) { | |
2577 // Delegate to CMScollector which knows how to coordinate between | |
2578 // this and any other CMS generations that it is responsible for | |
2579 // collecting. | |
2580 collector()->gc_prologue(full); | |
2581 } | |
2582 | |
2583 // This is a "private" interface for use by this generation's CMSCollector. | |
2584 // Not to be called directly by any other entity (for instance, | |
2585 // GenCollectedHeap, which calls the "public" gc_prologue method above). | |
2586 void ConcurrentMarkSweepGeneration::gc_prologue_work(bool full, | |
2587 bool registerClosure, ModUnionClosure* modUnionClosure) { | |
2588 assert(!incremental_collection_failed(), "Shouldn't be set yet"); | |
2589 assert(cmsSpace()->preconsumptionDirtyCardClosure() == NULL, | |
2590 "Should be NULL"); | |
2591 if (registerClosure) { | |
2592 cmsSpace()->setPreconsumptionDirtyCardClosure(modUnionClosure); | |
2593 } | |
2594 cmsSpace()->gc_prologue(); | |
2595 // Clear stat counters | |
2596 NOT_PRODUCT( | |
2597 assert(_numObjectsPromoted == 0, "check"); | |
2598 assert(_numWordsPromoted == 0, "check"); | |
2599 if (Verbose && PrintGC) { | |
2600 gclog_or_tty->print("Allocated "SIZE_FORMAT" objects, " | |
2601 SIZE_FORMAT" bytes concurrently", | |
2602 _numObjectsAllocated, _numWordsAllocated*sizeof(HeapWord)); | |
2603 } | |
2604 _numObjectsAllocated = 0; | |
2605 _numWordsAllocated = 0; | |
2606 ) | |
2607 } | |
2608 | |
2609 void CMSCollector::gc_epilogue(bool full) { | |
2610 // The following locking discipline assumes that we are only called | |
2611 // when the world is stopped. | |
2612 assert(SafepointSynchronize::is_at_safepoint(), | |
2613 "world is stopped assumption"); | |
2614 | |
2615 // Currently the CMS epilogue (see CompactibleFreeListSpace) merely checks | |
2616 // if linear allocation blocks need to be appropriately marked to allow the | |
2617 // the blocks to be parsable. We also check here whether we need to nudge the | |
2618 // CMS collector thread to start a new cycle (if it's not already active). | |
2619 assert( Thread::current()->is_VM_thread() | |
2620 || ( CMSScavengeBeforeRemark | |
2621 && Thread::current()->is_ConcurrentGC_thread()), | |
2622 "Incorrect thread type for epilogue execution"); | |
2623 | |
2624 if (!_between_prologue_and_epilogue) { | |
2625 // We have already been invoked; this is a gc_epilogue delegation | |
2626 // from yet another CMS generation that we are responsible for, just | |
2627 // ignore it since all relevant work has already been done. | |
2628 return; | |
2629 } | |
2630 assert(haveFreelistLocks(), "must have freelist locks"); | |
2631 assert_lock_strong(bitMapLock()); | |
2632 | |
2633 _cmsGen->gc_epilogue_work(full); | |
2634 _permGen->gc_epilogue_work(full); | |
2635 | |
2636 if (_collectorState == AbortablePreclean || _collectorState == Precleaning) { | |
2637 // in case sampling was not already enabled, enable it | |
2638 _start_sampling = true; | |
2639 } | |
2640 // reset _eden_chunk_array so sampling starts afresh | |
2641 _eden_chunk_index = 0; | |
2642 | |
2643 size_t cms_used = _cmsGen->cmsSpace()->used(); | |
2644 size_t perm_used = _permGen->cmsSpace()->used(); | |
2645 | |
2646 // update performance counters - this uses a special version of | |
2647 // update_counters() that allows the utilization to be passed as a | |
2648 // parameter, avoiding multiple calls to used(). | |
2649 // | |
2650 _cmsGen->update_counters(cms_used); | |
2651 _permGen->update_counters(perm_used); | |
2652 | |
2653 if (CMSIncrementalMode) { | |
2654 icms_update_allocation_limits(); | |
2655 } | |
2656 | |
2657 bitMapLock()->unlock(); | |
2658 releaseFreelistLocks(); | |
2659 | |
2660 _between_prologue_and_epilogue = false; // ready for next cycle | |
2661 } | |
2662 | |
2663 void ConcurrentMarkSweepGeneration::gc_epilogue(bool full) { | |
2664 collector()->gc_epilogue(full); | |
2665 | |
2666 // Also reset promotion tracking in par gc thread states. | |
2667 if (ParallelGCThreads > 0) { | |
2668 for (uint i = 0; i < ParallelGCThreads; i++) { | |
1145
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
2669 _par_gc_thread_states[i]->promo.stopTrackingPromotions(i); |
0 | 2670 } |
2671 } | |
2672 } | |
2673 | |
2674 void ConcurrentMarkSweepGeneration::gc_epilogue_work(bool full) { | |
2675 assert(!incremental_collection_failed(), "Should have been cleared"); | |
2676 cmsSpace()->setPreconsumptionDirtyCardClosure(NULL); | |
2677 cmsSpace()->gc_epilogue(); | |
2678 // Print stat counters | |
2679 NOT_PRODUCT( | |
2680 assert(_numObjectsAllocated == 0, "check"); | |
2681 assert(_numWordsAllocated == 0, "check"); | |
2682 if (Verbose && PrintGC) { | |
2683 gclog_or_tty->print("Promoted "SIZE_FORMAT" objects, " | |
2684 SIZE_FORMAT" bytes", | |
2685 _numObjectsPromoted, _numWordsPromoted*sizeof(HeapWord)); | |
2686 } | |
2687 _numObjectsPromoted = 0; | |
2688 _numWordsPromoted = 0; | |
2689 ) | |
2690 | |
2691 if (PrintGC && Verbose) { | |
2692 // Call down the chain in contiguous_available needs the freelistLock | |
2693 // so print this out before releasing the freeListLock. | |
2694 gclog_or_tty->print(" Contiguous available "SIZE_FORMAT" bytes ", | |
2695 contiguous_available()); | |
2696 } | |
2697 } | |
2698 | |
2699 #ifndef PRODUCT | |
2700 bool CMSCollector::have_cms_token() { | |
2701 Thread* thr = Thread::current(); | |
2702 if (thr->is_VM_thread()) { | |
2703 return ConcurrentMarkSweepThread::vm_thread_has_cms_token(); | |
2704 } else if (thr->is_ConcurrentGC_thread()) { | |
2705 return ConcurrentMarkSweepThread::cms_thread_has_cms_token(); | |
2706 } else if (thr->is_GC_task_thread()) { | |
2707 return ConcurrentMarkSweepThread::vm_thread_has_cms_token() && | |
2708 ParGCRareEvent_lock->owned_by_self(); | |
2709 } | |
2710 return false; | |
2711 } | |
2712 #endif | |
2713 | |
2714 // Check reachability of the given heap address in CMS generation, | |
2715 // treating all other generations as roots. | |
2716 bool CMSCollector::is_cms_reachable(HeapWord* addr) { | |
2717 // We could "guarantee" below, rather than assert, but i'll | |
2718 // leave these as "asserts" so that an adventurous debugger | |
2719 // could try this in the product build provided some subset of | |
2720 // the conditions were met, provided they were intersted in the | |
2721 // results and knew that the computation below wouldn't interfere | |
2722 // with other concurrent computations mutating the structures | |
2723 // being read or written. | |
2724 assert(SafepointSynchronize::is_at_safepoint(), | |
2725 "Else mutations in object graph will make answer suspect"); | |
2726 assert(have_cms_token(), "Should hold cms token"); | |
2727 assert(haveFreelistLocks(), "must hold free list locks"); | |
2728 assert_lock_strong(bitMapLock()); | |
2729 | |
2730 // Clear the marking bit map array before starting, but, just | |
2731 // for kicks, first report if the given address is already marked | |
2732 gclog_or_tty->print_cr("Start: Address 0x%x is%s marked", addr, | |
2733 _markBitMap.isMarked(addr) ? "" : " not"); | |
2734 | |
2735 if (verify_after_remark()) { | |
2736 MutexLockerEx x(verification_mark_bm()->lock(), Mutex::_no_safepoint_check_flag); | |
2737 bool result = verification_mark_bm()->isMarked(addr); | |
2738 gclog_or_tty->print_cr("TransitiveMark: Address 0x%x %s marked", addr, | |
2739 result ? "IS" : "is NOT"); | |
2740 return result; | |
2741 } else { | |
2742 gclog_or_tty->print_cr("Could not compute result"); | |
2743 return false; | |
2744 } | |
2745 } | |
2746 | |
2747 //////////////////////////////////////////////////////// | |
2748 // CMS Verification Support | |
2749 //////////////////////////////////////////////////////// | |
2750 // Following the remark phase, the following invariant | |
2751 // should hold -- each object in the CMS heap which is | |
2752 // marked in markBitMap() should be marked in the verification_mark_bm(). | |
2753 | |
2754 class VerifyMarkedClosure: public BitMapClosure { | |
2755 CMSBitMap* _marks; | |
2756 bool _failed; | |
2757 | |
2758 public: | |
2759 VerifyMarkedClosure(CMSBitMap* bm): _marks(bm), _failed(false) {} | |
2760 | |
342
37f87013dfd8
6711316: Open source the Garbage-First garbage collector
ysr
parents:
143
diff
changeset
|
2761 bool do_bit(size_t offset) { |
0 | 2762 HeapWord* addr = _marks->offsetToHeapWord(offset); |
2763 if (!_marks->isMarked(addr)) { | |
1145
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
2764 oop(addr)->print_on(gclog_or_tty); |
0 | 2765 gclog_or_tty->print_cr(" ("INTPTR_FORMAT" should have been marked)", addr); |
2766 _failed = true; | |
2767 } | |
342
37f87013dfd8
6711316: Open source the Garbage-First garbage collector
ysr
parents:
143
diff
changeset
|
2768 return true; |
0 | 2769 } |
2770 | |
2771 bool failed() { return _failed; } | |
2772 }; | |
2773 | |
2774 bool CMSCollector::verify_after_remark() { | |
2775 gclog_or_tty->print(" [Verifying CMS Marking... "); | |
2776 MutexLockerEx ml(verification_mark_bm()->lock(), Mutex::_no_safepoint_check_flag); | |
2777 static bool init = false; | |
2778 | |
2779 assert(SafepointSynchronize::is_at_safepoint(), | |
2780 "Else mutations in object graph will make answer suspect"); | |
2781 assert(have_cms_token(), | |
2782 "Else there may be mutual interference in use of " | |
2783 " verification data structures"); | |
2784 assert(_collectorState > Marking && _collectorState <= Sweeping, | |
2785 "Else marking info checked here may be obsolete"); | |
2786 assert(haveFreelistLocks(), "must hold free list locks"); | |
2787 assert_lock_strong(bitMapLock()); | |
2788 | |
2789 | |
2790 // Allocate marking bit map if not already allocated | |
2791 if (!init) { // first time | |
2792 if (!verification_mark_bm()->allocate(_span)) { | |
2793 return false; | |
2794 } | |
2795 init = true; | |
2796 } | |
2797 | |
2798 assert(verification_mark_stack()->isEmpty(), "Should be empty"); | |
2799 | |
2800 // Turn off refs discovery -- so we will be tracing through refs. | |
2801 // This is as intended, because by this time | |
2802 // GC must already have cleared any refs that need to be cleared, | |
2803 // and traced those that need to be marked; moreover, | |
2804 // the marking done here is not going to intefere in any | |
2805 // way with the marking information used by GC. | |
2806 NoRefDiscovery no_discovery(ref_processor()); | |
2807 | |
2808 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact;) | |
2809 | |
2810 // Clear any marks from a previous round | |
2811 verification_mark_bm()->clear_all(); | |
2812 assert(verification_mark_stack()->isEmpty(), "markStack should be empty"); | |
1145
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
2813 verify_work_stacks_empty(); |
0 | 2814 |
2815 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
2816 gch->ensure_parsability(false); // fill TLABs, but no need to retire them | |
2817 // Update the saved marks which may affect the root scans. | |
2818 gch->save_marks(); | |
2819 | |
2820 if (CMSRemarkVerifyVariant == 1) { | |
2821 // In this first variant of verification, we complete | |
2822 // all marking, then check if the new marks-verctor is | |
2823 // a subset of the CMS marks-vector. | |
2824 verify_after_remark_work_1(); | |
2825 } else if (CMSRemarkVerifyVariant == 2) { | |
2826 // In this second variant of verification, we flag an error | |
2827 // (i.e. an object reachable in the new marks-vector not reachable | |
2828 // in the CMS marks-vector) immediately, also indicating the | |
2829 // identify of an object (A) that references the unmarked object (B) -- | |
2830 // presumably, a mutation to A failed to be picked up by preclean/remark? | |
2831 verify_after_remark_work_2(); | |
2832 } else { | |
2833 warning("Unrecognized value %d for CMSRemarkVerifyVariant", | |
2834 CMSRemarkVerifyVariant); | |
2835 } | |
2836 gclog_or_tty->print(" done] "); | |
2837 return true; | |
2838 } | |
2839 | |
2840 void CMSCollector::verify_after_remark_work_1() { | |
2841 ResourceMark rm; | |
2842 HandleMark hm; | |
2843 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
2844 | |
2845 // Mark from roots one level into CMS | |
994
753cf9794df9
6885169: merge of 4957990 and 6863023 causes conflict on do_nmethods
jrose
parents:
993
diff
changeset
|
2846 MarkRefsIntoClosure notOlder(_span, verification_mark_bm()); |
0 | 2847 gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel. |
2848 | |
2849 gch->gen_process_strong_roots(_cmsGen->level(), | |
2850 true, // younger gens are roots | |
989
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
2851 true, // activate StrongRootsScope |
0 | 2852 true, // collecting perm gen |
2853 SharedHeap::ScanningOption(roots_scanning_options()), | |
989
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
2854 ¬Older, |
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
2855 true, // walk code active on stacks |
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
2856 NULL); |
0 | 2857 |
2858 // Now mark from the roots | |
2859 assert(_revisitStack.isEmpty(), "Should be empty"); | |
2860 MarkFromRootsClosure markFromRootsClosure(this, _span, | |
2861 verification_mark_bm(), verification_mark_stack(), &_revisitStack, | |
2862 false /* don't yield */, true /* verifying */); | |
2863 assert(_restart_addr == NULL, "Expected pre-condition"); | |
2864 verification_mark_bm()->iterate(&markFromRootsClosure); | |
2865 while (_restart_addr != NULL) { | |
2866 // Deal with stack overflow: by restarting at the indicated | |
2867 // address. | |
2868 HeapWord* ra = _restart_addr; | |
2869 markFromRootsClosure.reset(ra); | |
2870 _restart_addr = NULL; | |
2871 verification_mark_bm()->iterate(&markFromRootsClosure, ra, _span.end()); | |
2872 } | |
2873 assert(verification_mark_stack()->isEmpty(), "Should have been drained"); | |
2874 verify_work_stacks_empty(); | |
2875 // Should reset the revisit stack above, since no class tree | |
2876 // surgery is forthcoming. | |
2877 _revisitStack.reset(); // throwing away all contents | |
2878 | |
2879 // Marking completed -- now verify that each bit marked in | |
2880 // verification_mark_bm() is also marked in markBitMap(); flag all | |
2881 // errors by printing corresponding objects. | |
2882 VerifyMarkedClosure vcl(markBitMap()); | |
2883 verification_mark_bm()->iterate(&vcl); | |
2884 if (vcl.failed()) { | |
2885 gclog_or_tty->print("Verification failed"); | |
1145
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
2886 Universe::heap()->print_on(gclog_or_tty); |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
2887 fatal("CMS: failed marking verification after remark"); |
0 | 2888 } |
2889 } | |
2890 | |
2891 void CMSCollector::verify_after_remark_work_2() { | |
2892 ResourceMark rm; | |
2893 HandleMark hm; | |
2894 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
2895 | |
2896 // Mark from roots one level into CMS | |
2897 MarkRefsIntoVerifyClosure notOlder(_span, verification_mark_bm(), | |
994
753cf9794df9
6885169: merge of 4957990 and 6863023 causes conflict on do_nmethods
jrose
parents:
993
diff
changeset
|
2898 markBitMap()); |
0 | 2899 gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel. |
2900 gch->gen_process_strong_roots(_cmsGen->level(), | |
2901 true, // younger gens are roots | |
989
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
2902 true, // activate StrongRootsScope |
0 | 2903 true, // collecting perm gen |
2904 SharedHeap::ScanningOption(roots_scanning_options()), | |
989
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
2905 ¬Older, |
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
2906 true, // walk code active on stacks |
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
2907 NULL); |
0 | 2908 |
2909 // Now mark from the roots | |
2910 assert(_revisitStack.isEmpty(), "Should be empty"); | |
2911 MarkFromRootsVerifyClosure markFromRootsClosure(this, _span, | |
2912 verification_mark_bm(), markBitMap(), verification_mark_stack()); | |
2913 assert(_restart_addr == NULL, "Expected pre-condition"); | |
2914 verification_mark_bm()->iterate(&markFromRootsClosure); | |
2915 while (_restart_addr != NULL) { | |
2916 // Deal with stack overflow: by restarting at the indicated | |
2917 // address. | |
2918 HeapWord* ra = _restart_addr; | |
2919 markFromRootsClosure.reset(ra); | |
2920 _restart_addr = NULL; | |
2921 verification_mark_bm()->iterate(&markFromRootsClosure, ra, _span.end()); | |
2922 } | |
2923 assert(verification_mark_stack()->isEmpty(), "Should have been drained"); | |
2924 verify_work_stacks_empty(); | |
2925 // Should reset the revisit stack above, since no class tree | |
2926 // surgery is forthcoming. | |
2927 _revisitStack.reset(); // throwing away all contents | |
2928 | |
2929 // Marking completed -- now verify that each bit marked in | |
2930 // verification_mark_bm() is also marked in markBitMap(); flag all | |
2931 // errors by printing corresponding objects. | |
2932 VerifyMarkedClosure vcl(markBitMap()); | |
2933 verification_mark_bm()->iterate(&vcl); | |
2934 assert(!vcl.failed(), "Else verification above should not have succeeded"); | |
2935 } | |
2936 | |
2937 void ConcurrentMarkSweepGeneration::save_marks() { | |
2938 // delegate to CMS space | |
2939 cmsSpace()->save_marks(); | |
2940 for (uint i = 0; i < ParallelGCThreads; i++) { | |
2941 _par_gc_thread_states[i]->promo.startTrackingPromotions(); | |
2942 } | |
2943 } | |
2944 | |
2945 bool ConcurrentMarkSweepGeneration::no_allocs_since_save_marks() { | |
2946 return cmsSpace()->no_allocs_since_save_marks(); | |
2947 } | |
2948 | |
2949 #define CMS_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \ | |
2950 \ | |
2951 void ConcurrentMarkSweepGeneration:: \ | |
2952 oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) { \ | |
2953 cl->set_generation(this); \ | |
2954 cmsSpace()->oop_since_save_marks_iterate##nv_suffix(cl); \ | |
2955 cl->reset_generation(); \ | |
2956 save_marks(); \ | |
2957 } | |
2958 | |
2959 ALL_SINCE_SAVE_MARKS_CLOSURES(CMS_SINCE_SAVE_MARKS_DEFN) | |
2960 | |
2961 void | |
2962 ConcurrentMarkSweepGeneration::object_iterate_since_last_GC(ObjectClosure* blk) | |
2963 { | |
2964 // Not currently implemented; need to do the following. -- ysr. | |
2965 // dld -- I think that is used for some sort of allocation profiler. So it | |
2966 // really means the objects allocated by the mutator since the last | |
2967 // GC. We could potentially implement this cheaply by recording only | |
2968 // the direct allocations in a side data structure. | |
2969 // | |
2970 // I think we probably ought not to be required to support these | |
2971 // iterations at any arbitrary point; I think there ought to be some | |
2972 // call to enable/disable allocation profiling in a generation/space, | |
2973 // and the iterator ought to return the objects allocated in the | |
2974 // gen/space since the enable call, or the last iterator call (which | |
2975 // will probably be at a GC.) That way, for gens like CM&S that would | |
2976 // require some extra data structure to support this, we only pay the | |
2977 // cost when it's in use... | |
2978 cmsSpace()->object_iterate_since_last_GC(blk); | |
2979 } | |
2980 | |
2981 void | |
2982 ConcurrentMarkSweepGeneration::younger_refs_iterate(OopsInGenClosure* cl) { | |
2983 cl->set_generation(this); | |
2984 younger_refs_in_space_iterate(_cmsSpace, cl); | |
2985 cl->reset_generation(); | |
2986 } | |
2987 | |
2988 void | |
2989 ConcurrentMarkSweepGeneration::oop_iterate(MemRegion mr, OopClosure* cl) { | |
2990 if (freelistLock()->owned_by_self()) { | |
2991 Generation::oop_iterate(mr, cl); | |
2992 } else { | |
2993 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
2994 Generation::oop_iterate(mr, cl); | |
2995 } | |
2996 } | |
2997 | |
2998 void | |
2999 ConcurrentMarkSweepGeneration::oop_iterate(OopClosure* cl) { | |
3000 if (freelistLock()->owned_by_self()) { | |
3001 Generation::oop_iterate(cl); | |
3002 } else { | |
3003 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
3004 Generation::oop_iterate(cl); | |
3005 } | |
3006 } | |
3007 | |
3008 void | |
3009 ConcurrentMarkSweepGeneration::object_iterate(ObjectClosure* cl) { | |
3010 if (freelistLock()->owned_by_self()) { | |
3011 Generation::object_iterate(cl); | |
3012 } else { | |
3013 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
3014 Generation::object_iterate(cl); | |
3015 } | |
3016 } | |
3017 | |
3018 void | |
517
e9be0e04635a
6689653: JMapPerm fails with UseConcMarkSweepIncGC and compressed oops off
jmasa
parents:
457
diff
changeset
|
3019 ConcurrentMarkSweepGeneration::safe_object_iterate(ObjectClosure* cl) { |
e9be0e04635a
6689653: JMapPerm fails with UseConcMarkSweepIncGC and compressed oops off
jmasa
parents:
457
diff
changeset
|
3020 if (freelistLock()->owned_by_self()) { |
e9be0e04635a
6689653: JMapPerm fails with UseConcMarkSweepIncGC and compressed oops off
jmasa
parents:
457
diff
changeset
|
3021 Generation::safe_object_iterate(cl); |
e9be0e04635a
6689653: JMapPerm fails with UseConcMarkSweepIncGC and compressed oops off
jmasa
parents:
457
diff
changeset
|
3022 } else { |
e9be0e04635a
6689653: JMapPerm fails with UseConcMarkSweepIncGC and compressed oops off
jmasa
parents:
457
diff
changeset
|
3023 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); |
e9be0e04635a
6689653: JMapPerm fails with UseConcMarkSweepIncGC and compressed oops off
jmasa
parents:
457
diff
changeset
|
3024 Generation::safe_object_iterate(cl); |
e9be0e04635a
6689653: JMapPerm fails with UseConcMarkSweepIncGC and compressed oops off
jmasa
parents:
457
diff
changeset
|
3025 } |
e9be0e04635a
6689653: JMapPerm fails with UseConcMarkSweepIncGC and compressed oops off
jmasa
parents:
457
diff
changeset
|
3026 } |
e9be0e04635a
6689653: JMapPerm fails with UseConcMarkSweepIncGC and compressed oops off
jmasa
parents:
457
diff
changeset
|
3027 |
e9be0e04635a
6689653: JMapPerm fails with UseConcMarkSweepIncGC and compressed oops off
jmasa
parents:
457
diff
changeset
|
3028 void |
0 | 3029 ConcurrentMarkSweepGeneration::pre_adjust_pointers() { |
3030 } | |
3031 | |
3032 void | |
3033 ConcurrentMarkSweepGeneration::post_compact() { | |
3034 } | |
3035 | |
3036 void | |
3037 ConcurrentMarkSweepGeneration::prepare_for_verify() { | |
3038 // Fix the linear allocation blocks to look like free blocks. | |
3039 | |
3040 // Locks are normally acquired/released in gc_prologue/gc_epilogue, but those | |
3041 // are not called when the heap is verified during universe initialization and | |
3042 // at vm shutdown. | |
3043 if (freelistLock()->owned_by_self()) { | |
3044 cmsSpace()->prepare_for_verify(); | |
3045 } else { | |
3046 MutexLockerEx fll(freelistLock(), Mutex::_no_safepoint_check_flag); | |
3047 cmsSpace()->prepare_for_verify(); | |
3048 } | |
3049 } | |
3050 | |
3051 void | |
3052 ConcurrentMarkSweepGeneration::verify(bool allow_dirty /* ignored */) { | |
3053 // Locks are normally acquired/released in gc_prologue/gc_epilogue, but those | |
3054 // are not called when the heap is verified during universe initialization and | |
3055 // at vm shutdown. | |
3056 if (freelistLock()->owned_by_self()) { | |
3057 cmsSpace()->verify(false /* ignored */); | |
3058 } else { | |
3059 MutexLockerEx fll(freelistLock(), Mutex::_no_safepoint_check_flag); | |
3060 cmsSpace()->verify(false /* ignored */); | |
3061 } | |
3062 } | |
3063 | |
3064 void CMSCollector::verify(bool allow_dirty /* ignored */) { | |
3065 _cmsGen->verify(allow_dirty); | |
3066 _permGen->verify(allow_dirty); | |
3067 } | |
3068 | |
3069 #ifndef PRODUCT | |
3070 bool CMSCollector::overflow_list_is_empty() const { | |
3071 assert(_num_par_pushes >= 0, "Inconsistency"); | |
3072 if (_overflow_list == NULL) { | |
3073 assert(_num_par_pushes == 0, "Inconsistency"); | |
3074 } | |
3075 return _overflow_list == NULL; | |
3076 } | |
3077 | |
3078 // The methods verify_work_stacks_empty() and verify_overflow_empty() | |
3079 // merely consolidate assertion checks that appear to occur together frequently. | |
3080 void CMSCollector::verify_work_stacks_empty() const { | |
3081 assert(_markStack.isEmpty(), "Marking stack should be empty"); | |
3082 assert(overflow_list_is_empty(), "Overflow list should be empty"); | |
3083 } | |
3084 | |
3085 void CMSCollector::verify_overflow_empty() const { | |
3086 assert(overflow_list_is_empty(), "Overflow list should be empty"); | |
3087 assert(no_preserved_marks(), "No preserved marks"); | |
3088 } | |
3089 #endif // PRODUCT | |
3090 | |
94
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3091 // Decide if we want to enable class unloading as part of the |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3092 // ensuing concurrent GC cycle. We will collect the perm gen and |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3093 // unload classes if it's the case that: |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3094 // (1) an explicit gc request has been made and the flag |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3095 // ExplicitGCInvokesConcurrentAndUnloadsClasses is set, OR |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3096 // (2) (a) class unloading is enabled at the command line, and |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3097 // (b) (i) perm gen threshold has been crossed, or |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3098 // (ii) old gen is getting really full, or |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3099 // (iii) the previous N CMS collections did not collect the |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3100 // perm gen |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3101 // NOTE: Provided there is no change in the state of the heap between |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3102 // calls to this method, it should have idempotent results. Moreover, |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3103 // its results should be monotonically increasing (i.e. going from 0 to 1, |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3104 // but not 1 to 0) between successive calls between which the heap was |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3105 // not collected. For the implementation below, it must thus rely on |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3106 // the property that concurrent_cycles_since_last_unload() |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3107 // will not decrease unless a collection cycle happened and that |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3108 // _permGen->should_concurrent_collect() and _cmsGen->is_too_full() are |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3109 // themselves also monotonic in that sense. See check_monotonicity() |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3110 // below. |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3111 bool CMSCollector::update_should_unload_classes() { |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3112 _should_unload_classes = false; |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3113 // Condition 1 above |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3114 if (_full_gc_requested && ExplicitGCInvokesConcurrentAndUnloadsClasses) { |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3115 _should_unload_classes = true; |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3116 } else if (CMSClassUnloadingEnabled) { // Condition 2.a above |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3117 // Disjuncts 2.b.(i,ii,iii) above |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3118 _should_unload_classes = (concurrent_cycles_since_last_unload() >= |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3119 CMSClassUnloadingMaxInterval) |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3120 || _permGen->should_concurrent_collect() |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3121 || _cmsGen->is_too_full(); |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3122 } |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3123 return _should_unload_classes; |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3124 } |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3125 |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3126 bool ConcurrentMarkSweepGeneration::is_too_full() const { |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3127 bool res = should_concurrent_collect(); |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3128 res = res && (occupancy() > (double)CMSIsTooFullPercentage/100.0); |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3129 return res; |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3130 } |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3131 |
0 | 3132 void CMSCollector::setup_cms_unloading_and_verification_state() { |
3133 const bool should_verify = VerifyBeforeGC || VerifyAfterGC || VerifyDuringGC | |
3134 || VerifyBeforeExit; | |
3135 const int rso = SharedHeap::SO_Symbols | SharedHeap::SO_Strings | |
3136 | SharedHeap::SO_CodeCache; | |
3137 | |
94
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3138 if (should_unload_classes()) { // Should unload classes this cycle |
0 | 3139 remove_root_scanning_option(rso); // Shrink the root set appropriately |
3140 set_verifying(should_verify); // Set verification state for this cycle | |
3141 return; // Nothing else needs to be done at this time | |
3142 } | |
3143 | |
3144 // Not unloading classes this cycle | |
94
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3145 assert(!should_unload_classes(), "Inconsitency!"); |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
3146 if ((!verifying() || unloaded_classes_last_cycle()) && should_verify) { |
0 | 3147 // We were not verifying, or we _were_ unloading classes in the last cycle, |
3148 // AND some verification options are enabled this cycle; in this case, | |
3149 // we must make sure that the deadness map is allocated if not already so, | |
3150 // and cleared (if already allocated previously -- | |
3151 // CMSBitMap::sizeInBits() is used to determine if it's allocated). | |
3152 if (perm_gen_verify_bit_map()->sizeInBits() == 0) { | |
3153 if (!perm_gen_verify_bit_map()->allocate(_permGen->reserved())) { | |
3154 warning("Failed to allocate permanent generation verification CMS Bit Map;\n" | |
3155 "permanent generation verification disabled"); | |
3156 return; // Note that we leave verification disabled, so we'll retry this | |
3157 // allocation next cycle. We _could_ remember this failure | |
3158 // and skip further attempts and permanently disable verification | |
3159 // attempts if that is considered more desirable. | |
3160 } | |
3161 assert(perm_gen_verify_bit_map()->covers(_permGen->reserved()), | |
3162 "_perm_gen_ver_bit_map inconsistency?"); | |
3163 } else { | |
3164 perm_gen_verify_bit_map()->clear_all(); | |
3165 } | |
3166 // Include symbols, strings and code cache elements to prevent their resurrection. | |
3167 add_root_scanning_option(rso); | |
3168 set_verifying(true); | |
3169 } else if (verifying() && !should_verify) { | |
3170 // We were verifying, but some verification flags got disabled. | |
3171 set_verifying(false); | |
3172 // Exclude symbols, strings and code cache elements from root scanning to | |
3173 // reduce IM and RM pauses. | |
3174 remove_root_scanning_option(rso); | |
3175 } | |
3176 } | |
3177 | |
3178 | |
3179 #ifndef PRODUCT | |
3180 HeapWord* CMSCollector::block_start(const void* p) const { | |
3181 const HeapWord* addr = (HeapWord*)p; | |
3182 if (_span.contains(p)) { | |
3183 if (_cmsGen->cmsSpace()->is_in_reserved(addr)) { | |
3184 return _cmsGen->cmsSpace()->block_start(p); | |
3185 } else { | |
3186 assert(_permGen->cmsSpace()->is_in_reserved(addr), | |
3187 "Inconsistent _span?"); | |
3188 return _permGen->cmsSpace()->block_start(p); | |
3189 } | |
3190 } | |
3191 return NULL; | |
3192 } | |
3193 #endif | |
3194 | |
3195 HeapWord* | |
3196 ConcurrentMarkSweepGeneration::expand_and_allocate(size_t word_size, | |
3197 bool tlab, | |
3198 bool parallel) { | |
3199 assert(!tlab, "Can't deal with TLAB allocation"); | |
3200 MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag); | |
3201 expand(word_size*HeapWordSize, MinHeapDeltaBytes, | |
3202 CMSExpansionCause::_satisfy_allocation); | |
3203 if (GCExpandToAllocateDelayMillis > 0) { | |
3204 os::sleep(Thread::current(), GCExpandToAllocateDelayMillis, false); | |
3205 } | |
9
173195ff483a
6642634: Test nsk/regression/b6186200 crashed with SIGSEGV
ysr
parents:
7
diff
changeset
|
3206 return have_lock_and_allocate(word_size, tlab); |
0 | 3207 } |
3208 | |
3209 // YSR: All of this generation expansion/shrinking stuff is an exact copy of | |
3210 // OneContigSpaceCardGeneration, which makes me wonder if we should move this | |
3211 // to CardGeneration and share it... | |
271
818a18cd69a8
6730514: assertion failure in mangling code when expanding by 0 bytes
jmasa
parents:
196
diff
changeset
|
3212 bool ConcurrentMarkSweepGeneration::expand(size_t bytes, size_t expand_bytes) { |
818a18cd69a8
6730514: assertion failure in mangling code when expanding by 0 bytes
jmasa
parents:
196
diff
changeset
|
3213 return CardGeneration::expand(bytes, expand_bytes); |
818a18cd69a8
6730514: assertion failure in mangling code when expanding by 0 bytes
jmasa
parents:
196
diff
changeset
|
3214 } |
818a18cd69a8
6730514: assertion failure in mangling code when expanding by 0 bytes
jmasa
parents:
196
diff
changeset
|
3215 |
0 | 3216 void ConcurrentMarkSweepGeneration::expand(size_t bytes, size_t expand_bytes, |
3217 CMSExpansionCause::Cause cause) | |
3218 { | |
271
818a18cd69a8
6730514: assertion failure in mangling code when expanding by 0 bytes
jmasa
parents:
196
diff
changeset
|
3219 |
818a18cd69a8
6730514: assertion failure in mangling code when expanding by 0 bytes
jmasa
parents:
196
diff
changeset
|
3220 bool success = expand(bytes, expand_bytes); |
818a18cd69a8
6730514: assertion failure in mangling code when expanding by 0 bytes
jmasa
parents:
196
diff
changeset
|
3221 |
0 | 3222 // remember why we expanded; this information is used |
3223 // by shouldConcurrentCollect() when making decisions on whether to start | |
3224 // a new CMS cycle. | |
3225 if (success) { | |
3226 set_expansion_cause(cause); | |
3227 if (PrintGCDetails && Verbose) { | |
3228 gclog_or_tty->print_cr("Expanded CMS gen for %s", | |
3229 CMSExpansionCause::to_string(cause)); | |
3230 } | |
3231 } | |
3232 } | |
3233 | |
3234 HeapWord* ConcurrentMarkSweepGeneration::expand_and_par_lab_allocate(CMSParGCThreadState* ps, size_t word_sz) { | |
3235 HeapWord* res = NULL; | |
3236 MutexLocker x(ParGCRareEvent_lock); | |
3237 while (true) { | |
3238 // Expansion by some other thread might make alloc OK now: | |
3239 res = ps->lab.alloc(word_sz); | |
3240 if (res != NULL) return res; | |
3241 // If there's not enough expansion space available, give up. | |
3242 if (_virtual_space.uncommitted_size() < (word_sz * HeapWordSize)) { | |
3243 return NULL; | |
3244 } | |
3245 // Otherwise, we try expansion. | |
3246 expand(word_sz*HeapWordSize, MinHeapDeltaBytes, | |
3247 CMSExpansionCause::_allocate_par_lab); | |
3248 // Now go around the loop and try alloc again; | |
3249 // A competing par_promote might beat us to the expansion space, | |
3250 // so we may go around the loop again if promotion fails agaion. | |
3251 if (GCExpandToAllocateDelayMillis > 0) { | |
3252 os::sleep(Thread::current(), GCExpandToAllocateDelayMillis, false); | |
3253 } | |
3254 } | |
3255 } | |
3256 | |
3257 | |
3258 bool ConcurrentMarkSweepGeneration::expand_and_ensure_spooling_space( | |
3259 PromotionInfo* promo) { | |
3260 MutexLocker x(ParGCRareEvent_lock); | |
3261 size_t refill_size_bytes = promo->refillSize() * HeapWordSize; | |
3262 while (true) { | |
3263 // Expansion by some other thread might make alloc OK now: | |
3264 if (promo->ensure_spooling_space()) { | |
3265 assert(promo->has_spooling_space(), | |
3266 "Post-condition of successful ensure_spooling_space()"); | |
3267 return true; | |
3268 } | |
3269 // If there's not enough expansion space available, give up. | |
3270 if (_virtual_space.uncommitted_size() < refill_size_bytes) { | |
3271 return false; | |
3272 } | |
3273 // Otherwise, we try expansion. | |
3274 expand(refill_size_bytes, MinHeapDeltaBytes, | |
3275 CMSExpansionCause::_allocate_par_spooling_space); | |
3276 // Now go around the loop and try alloc again; | |
3277 // A competing allocation might beat us to the expansion space, | |
3278 // so we may go around the loop again if allocation fails again. | |
3279 if (GCExpandToAllocateDelayMillis > 0) { | |
3280 os::sleep(Thread::current(), GCExpandToAllocateDelayMillis, false); | |
3281 } | |
3282 } | |
3283 } | |
3284 | |
3285 | |
3286 | |
3287 void ConcurrentMarkSweepGeneration::shrink(size_t bytes) { | |
3288 assert_locked_or_safepoint(Heap_lock); | |
3289 size_t size = ReservedSpace::page_align_size_down(bytes); | |
3290 if (size > 0) { | |
3291 shrink_by(size); | |
3292 } | |
3293 } | |
3294 | |
3295 bool ConcurrentMarkSweepGeneration::grow_by(size_t bytes) { | |
3296 assert_locked_or_safepoint(Heap_lock); | |
3297 bool result = _virtual_space.expand_by(bytes); | |
3298 if (result) { | |
3299 HeapWord* old_end = _cmsSpace->end(); | |
3300 size_t new_word_size = | |
3301 heap_word_size(_virtual_space.committed_size()); | |
3302 MemRegion mr(_cmsSpace->bottom(), new_word_size); | |
3303 _bts->resize(new_word_size); // resize the block offset shared array | |
3304 Universe::heap()->barrier_set()->resize_covered_region(mr); | |
3305 // Hmmmm... why doesn't CFLS::set_end verify locking? | |
3306 // This is quite ugly; FIX ME XXX | |
1145
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
3307 _cmsSpace->assert_locked(freelistLock()); |
0 | 3308 _cmsSpace->set_end((HeapWord*)_virtual_space.high()); |
3309 | |
3310 // update the space and generation capacity counters | |
3311 if (UsePerfData) { | |
3312 _space_counters->update_capacity(); | |
3313 _gen_counters->update_all(); | |
3314 } | |
3315 | |
3316 if (Verbose && PrintGC) { | |
3317 size_t new_mem_size = _virtual_space.committed_size(); | |
3318 size_t old_mem_size = new_mem_size - bytes; | |
3319 gclog_or_tty->print_cr("Expanding %s from %ldK by %ldK to %ldK", | |
3320 name(), old_mem_size/K, bytes/K, new_mem_size/K); | |
3321 } | |
3322 } | |
3323 return result; | |
3324 } | |
3325 | |
3326 bool ConcurrentMarkSweepGeneration::grow_to_reserved() { | |
3327 assert_locked_or_safepoint(Heap_lock); | |
3328 bool success = true; | |
3329 const size_t remaining_bytes = _virtual_space.uncommitted_size(); | |
3330 if (remaining_bytes > 0) { | |
3331 success = grow_by(remaining_bytes); | |
3332 DEBUG_ONLY(if (!success) warning("grow to reserved failed");) | |
3333 } | |
3334 return success; | |
3335 } | |
3336 | |
3337 void ConcurrentMarkSweepGeneration::shrink_by(size_t bytes) { | |
3338 assert_locked_or_safepoint(Heap_lock); | |
3339 assert_lock_strong(freelistLock()); | |
3340 // XXX Fix when compaction is implemented. | |
3341 warning("Shrinking of CMS not yet implemented"); | |
3342 return; | |
3343 } | |
3344 | |
3345 | |
3346 // Simple ctor/dtor wrapper for accounting & timer chores around concurrent | |
3347 // phases. | |
3348 class CMSPhaseAccounting: public StackObj { | |
3349 public: | |
3350 CMSPhaseAccounting(CMSCollector *collector, | |
3351 const char *phase, | |
3352 bool print_cr = true); | |
3353 ~CMSPhaseAccounting(); | |
3354 | |
3355 private: | |
3356 CMSCollector *_collector; | |
3357 const char *_phase; | |
3358 elapsedTimer _wallclock; | |
3359 bool _print_cr; | |
3360 | |
3361 public: | |
3362 // Not MT-safe; so do not pass around these StackObj's | |
3363 // where they may be accessed by other threads. | |
3364 jlong wallclock_millis() { | |
3365 assert(_wallclock.is_active(), "Wall clock should not stop"); | |
3366 _wallclock.stop(); // to record time | |
3367 jlong ret = _wallclock.milliseconds(); | |
3368 _wallclock.start(); // restart | |
3369 return ret; | |
3370 } | |
3371 }; | |
3372 | |
3373 CMSPhaseAccounting::CMSPhaseAccounting(CMSCollector *collector, | |
3374 const char *phase, | |
3375 bool print_cr) : | |
3376 _collector(collector), _phase(phase), _print_cr(print_cr) { | |
3377 | |
3378 if (PrintCMSStatistics != 0) { | |
3379 _collector->resetYields(); | |
3380 } | |
3381 if (PrintGCDetails && PrintGCTimeStamps) { | |
3382 gclog_or_tty->date_stamp(PrintGCDateStamps); | |
3383 gclog_or_tty->stamp(); | |
3384 gclog_or_tty->print_cr(": [%s-concurrent-%s-start]", | |
3385 _collector->cmsGen()->short_name(), _phase); | |
3386 } | |
3387 _collector->resetTimer(); | |
3388 _wallclock.start(); | |
3389 _collector->startTimer(); | |
3390 } | |
3391 | |
3392 CMSPhaseAccounting::~CMSPhaseAccounting() { | |
3393 assert(_wallclock.is_active(), "Wall clock should not have stopped"); | |
3394 _collector->stopTimer(); | |
3395 _wallclock.stop(); | |
3396 if (PrintGCDetails) { | |
3397 gclog_or_tty->date_stamp(PrintGCDateStamps); | |
3398 if (PrintGCTimeStamps) { | |
3399 gclog_or_tty->stamp(); | |
3400 gclog_or_tty->print(": "); | |
3401 } | |
3402 gclog_or_tty->print("[%s-concurrent-%s: %3.3f/%3.3f secs]", | |
3403 _collector->cmsGen()->short_name(), | |
3404 _phase, _collector->timerValue(), _wallclock.seconds()); | |
3405 if (_print_cr) { | |
3406 gclog_or_tty->print_cr(""); | |
3407 } | |
3408 if (PrintCMSStatistics != 0) { | |
3409 gclog_or_tty->print_cr(" (CMS-concurrent-%s yielded %d times)", _phase, | |
3410 _collector->yields()); | |
3411 } | |
3412 } | |
3413 } | |
3414 | |
3415 // CMS work | |
3416 | |
3417 // Checkpoint the roots into this generation from outside | |
3418 // this generation. [Note this initial checkpoint need only | |
3419 // be approximate -- we'll do a catch up phase subsequently.] | |
3420 void CMSCollector::checkpointRootsInitial(bool asynch) { | |
3421 assert(_collectorState == InitialMarking, "Wrong collector state"); | |
3422 check_correct_thread_executing(); | |
3423 ReferenceProcessor* rp = ref_processor(); | |
3424 SpecializationStats::clear(); | |
3425 assert(_restart_addr == NULL, "Control point invariant"); | |
3426 if (asynch) { | |
3427 // acquire locks for subsequent manipulations | |
3428 MutexLockerEx x(bitMapLock(), | |
3429 Mutex::_no_safepoint_check_flag); | |
3430 checkpointRootsInitialWork(asynch); | |
3431 rp->verify_no_references_recorded(); | |
3432 rp->enable_discovery(); // enable ("weak") refs discovery | |
3433 _collectorState = Marking; | |
3434 } else { | |
3435 // (Weak) Refs discovery: this is controlled from genCollectedHeap::do_collection | |
3436 // which recognizes if we are a CMS generation, and doesn't try to turn on | |
3437 // discovery; verify that they aren't meddling. | |
3438 assert(!rp->discovery_is_atomic(), | |
3439 "incorrect setting of discovery predicate"); | |
3440 assert(!rp->discovery_enabled(), "genCollectedHeap shouldn't control " | |
3441 "ref discovery for this generation kind"); | |
3442 // already have locks | |
3443 checkpointRootsInitialWork(asynch); | |
3444 rp->enable_discovery(); // now enable ("weak") refs discovery | |
3445 _collectorState = Marking; | |
3446 } | |
3447 SpecializationStats::print(); | |
3448 } | |
3449 | |
3450 void CMSCollector::checkpointRootsInitialWork(bool asynch) { | |
3451 assert(SafepointSynchronize::is_at_safepoint(), "world should be stopped"); | |
3452 assert(_collectorState == InitialMarking, "just checking"); | |
3453 | |
3454 // If there has not been a GC[n-1] since last GC[n] cycle completed, | |
3455 // precede our marking with a collection of all | |
3456 // younger generations to keep floating garbage to a minimum. | |
3457 // XXX: we won't do this for now -- it's an optimization to be done later. | |
3458 | |
3459 // already have locks | |
3460 assert_lock_strong(bitMapLock()); | |
3461 assert(_markBitMap.isAllClear(), "was reset at end of previous cycle"); | |
3462 | |
3463 // Setup the verification and class unloading state for this | |
3464 // CMS collection cycle. | |
3465 setup_cms_unloading_and_verification_state(); | |
3466 | |
3467 NOT_PRODUCT(TraceTime t("\ncheckpointRootsInitialWork", | |
3468 PrintGCDetails && Verbose, true, gclog_or_tty);) | |
3469 if (UseAdaptiveSizePolicy) { | |
3470 size_policy()->checkpoint_roots_initial_begin(); | |
3471 } | |
3472 | |
3473 // Reset all the PLAB chunk arrays if necessary. | |
3474 if (_survivor_plab_array != NULL && !CMSPLABRecordAlways) { | |
3475 reset_survivor_plab_arrays(); | |
3476 } | |
3477 | |
3478 ResourceMark rm; | |
3479 HandleMark hm; | |
3480 | |
3481 FalseClosure falseClosure; | |
3482 // In the case of a synchronous collection, we will elide the | |
3483 // 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
|
3484 // in this step. |
753cf9794df9
6885169: merge of 4957990 and 6863023 causes conflict on do_nmethods
jrose
parents:
993
diff
changeset
|
3485 // 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
parents:
993
diff
changeset
|
3486 // If 'async' is true, we can relax the nmethod tracing. |
753cf9794df9
6885169: merge of 4957990 and 6863023 causes conflict on do_nmethods
jrose
parents:
993
diff
changeset
|
3487 MarkRefsIntoClosure notOlder(_span, &_markBitMap); |
0 | 3488 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
3489 | |
3490 verify_work_stacks_empty(); | |
3491 verify_overflow_empty(); | |
3492 | |
3493 gch->ensure_parsability(false); // fill TLABs, but no need to retire them | |
3494 // Update the saved marks which may affect the root scans. | |
3495 gch->save_marks(); | |
3496 | |
3497 // weak reference processing has not started yet. | |
3498 ref_processor()->set_enqueuing_is_done(false); | |
3499 | |
3500 { | |
935 | 3501 // This is not needed. DEBUG_ONLY(RememberKlassesChecker imx(true);) |
0 | 3502 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact;) |
3503 gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel. | |
3504 gch->gen_process_strong_roots(_cmsGen->level(), | |
3505 true, // younger gens are roots | |
989
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
3506 true, // activate StrongRootsScope |
0 | 3507 true, // collecting perm gen |
3508 SharedHeap::ScanningOption(roots_scanning_options()), | |
989
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
3509 ¬Older, |
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
3510 true, // walk all of code cache if (so & SO_CodeCache) |
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
3511 NULL); |
0 | 3512 } |
3513 | |
3514 // Clear mod-union table; it will be dirtied in the prologue of | |
3515 // CMS generation per each younger generation collection. | |
3516 | |
3517 assert(_modUnionTable.isAllClear(), | |
3518 "Was cleared in most recent final checkpoint phase" | |
3519 " or no bits are set in the gc_prologue before the start of the next " | |
3520 "subsequent marking phase."); | |
3521 | |
3522 // Temporarily disabled, since pre/post-consumption closures don't | |
3523 // care about precleaned cards | |
3524 #if 0 | |
3525 { | |
3526 MemRegion mr = MemRegion((HeapWord*)_virtual_space.low(), | |
3527 (HeapWord*)_virtual_space.high()); | |
3528 _ct->ct_bs()->preclean_dirty_cards(mr); | |
3529 } | |
3530 #endif | |
3531 | |
3532 // Save the end of the used_region of the constituent generations | |
3533 // to be used to limit the extent of sweep in each generation. | |
3534 save_sweep_limits(); | |
3535 if (UseAdaptiveSizePolicy) { | |
3536 size_policy()->checkpoint_roots_initial_end(gch->gc_cause()); | |
3537 } | |
3538 verify_overflow_empty(); | |
3539 } | |
3540 | |
3541 bool CMSCollector::markFromRoots(bool asynch) { | |
3542 // we might be tempted to assert that: | |
3543 // assert(asynch == !SafepointSynchronize::is_at_safepoint(), | |
3544 // "inconsistent argument?"); | |
3545 // However that wouldn't be right, because it's possible that | |
3546 // a safepoint is indeed in progress as a younger generation | |
3547 // stop-the-world GC happens even as we mark in this generation. | |
3548 assert(_collectorState == Marking, "inconsistent state?"); | |
3549 check_correct_thread_executing(); | |
3550 verify_overflow_empty(); | |
3551 | |
3552 bool res; | |
3553 if (asynch) { | |
3554 | |
3555 // Start the timers for adaptive size policy for the concurrent phases | |
3556 // Do it here so that the foreground MS can use the concurrent | |
3557 // timer since a foreground MS might has the sweep done concurrently | |
3558 // or STW. | |
3559 if (UseAdaptiveSizePolicy) { | |
3560 size_policy()->concurrent_marking_begin(); | |
3561 } | |
3562 | |
3563 // Weak ref discovery note: We may be discovering weak | |
3564 // refs in this generation concurrent (but interleaved) with | |
3565 // weak ref discovery by a younger generation collector. | |
3566 | |
3567 CMSTokenSyncWithLocks ts(true, bitMapLock()); | |
3568 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
3569 CMSPhaseAccounting pa(this, "mark", !PrintGCDetails); | |
3570 res = markFromRootsWork(asynch); | |
3571 if (res) { | |
3572 _collectorState = Precleaning; | |
3573 } else { // We failed and a foreground collection wants to take over | |
3574 assert(_foregroundGCIsActive, "internal state inconsistency"); | |
3575 assert(_restart_addr == NULL, "foreground will restart from scratch"); | |
3576 if (PrintGCDetails) { | |
3577 gclog_or_tty->print_cr("bailing out to foreground collection"); | |
3578 } | |
3579 } | |
3580 if (UseAdaptiveSizePolicy) { | |
3581 size_policy()->concurrent_marking_end(); | |
3582 } | |
3583 } else { | |
3584 assert(SafepointSynchronize::is_at_safepoint(), | |
3585 "inconsistent with asynch == false"); | |
3586 if (UseAdaptiveSizePolicy) { | |
3587 size_policy()->ms_collection_marking_begin(); | |
3588 } | |
3589 // already have locks | |
3590 res = markFromRootsWork(asynch); | |
3591 _collectorState = FinalMarking; | |
3592 if (UseAdaptiveSizePolicy) { | |
3593 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
3594 size_policy()->ms_collection_marking_end(gch->gc_cause()); | |
3595 } | |
3596 } | |
3597 verify_overflow_empty(); | |
3598 return res; | |
3599 } | |
3600 | |
3601 bool CMSCollector::markFromRootsWork(bool asynch) { | |
3602 // iterate over marked bits in bit map, doing a full scan and mark | |
3603 // from these roots using the following algorithm: | |
3604 // . if oop is to the right of the current scan pointer, | |
3605 // mark corresponding bit (we'll process it later) | |
3606 // . else (oop is to left of current scan pointer) | |
3607 // push oop on marking stack | |
3608 // . drain the marking stack | |
3609 | |
3610 // Note that when we do a marking step we need to hold the | |
3611 // bit map lock -- recall that direct allocation (by mutators) | |
3612 // and promotion (by younger generation collectors) is also | |
3613 // marking the bit map. [the so-called allocate live policy.] | |
3614 // Because the implementation of bit map marking is not | |
3615 // robust wrt simultaneous marking of bits in the same word, | |
3616 // we need to make sure that there is no such interference | |
3617 // between concurrent such updates. | |
3618 | |
3619 // already have locks | |
3620 assert_lock_strong(bitMapLock()); | |
3621 | |
3622 // Clear the revisit stack, just in case there are any | |
3623 // obsolete contents from a short-circuited previous CMS cycle. | |
3624 _revisitStack.reset(); | |
3625 verify_work_stacks_empty(); | |
3626 verify_overflow_empty(); | |
3627 assert(_revisitStack.isEmpty(), "tabula rasa"); | |
1190
4788266644c1
6895236: CMS: cmsOopClosures.inline.hpp:43 assert(..., "Should remember klasses in this context")
jmasa
parents:
1145
diff
changeset
|
3628 DEBUG_ONLY(RememberKlassesChecker cmx(should_unload_classes());) |
0 | 3629 bool result = false; |
1284 | 3630 if (CMSConcurrentMTEnabled && ConcGCThreads > 0) { |
0 | 3631 result = do_marking_mt(asynch); |
3632 } else { | |
3633 result = do_marking_st(asynch); | |
3634 } | |
3635 return result; | |
3636 } | |
3637 | |
3638 // Forward decl | |
3639 class CMSConcMarkingTask; | |
3640 | |
3641 class CMSConcMarkingTerminator: public ParallelTaskTerminator { | |
3642 CMSCollector* _collector; | |
3643 CMSConcMarkingTask* _task; | |
3644 bool _yield; | |
3645 protected: | |
3646 virtual void yield(); | |
3647 public: | |
3648 // "n_threads" is the number of threads to be terminated. | |
3649 // "queue_set" is a set of work queues of other threads. | |
3650 // "collector" is the CMS collector associated with this task terminator. | |
3651 // "yield" indicates whether we need the gang as a whole to yield. | |
3652 CMSConcMarkingTerminator(int n_threads, TaskQueueSetSuper* queue_set, | |
3653 CMSCollector* collector, bool yield) : | |
3654 ParallelTaskTerminator(n_threads, queue_set), | |
3655 _collector(collector), | |
3656 _yield(yield) { } | |
3657 | |
3658 void set_task(CMSConcMarkingTask* task) { | |
3659 _task = task; | |
3660 } | |
3661 }; | |
3662 | |
3663 // MT Concurrent Marking Task | |
3664 class CMSConcMarkingTask: public YieldingFlexibleGangTask { | |
3665 CMSCollector* _collector; | |
3666 YieldingFlexibleWorkGang* _workers; // the whole gang | |
3667 int _n_workers; // requested/desired # workers | |
3668 bool _asynch; | |
3669 bool _result; | |
3670 CompactibleFreeListSpace* _cms_space; | |
3671 CompactibleFreeListSpace* _perm_space; | |
3672 HeapWord* _global_finger; | |
340
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3673 HeapWord* _restart_addr; |
0 | 3674 |
3675 // Exposed here for yielding support | |
3676 Mutex* const _bit_map_lock; | |
3677 | |
3678 // The per thread work queues, available here for stealing | |
3679 OopTaskQueueSet* _task_queues; | |
3680 CMSConcMarkingTerminator _term; | |
3681 | |
3682 public: | |
3683 CMSConcMarkingTask(CMSCollector* collector, | |
3684 CompactibleFreeListSpace* cms_space, | |
3685 CompactibleFreeListSpace* perm_space, | |
3686 bool asynch, int n_workers, | |
3687 YieldingFlexibleWorkGang* workers, | |
3688 OopTaskQueueSet* task_queues): | |
3689 YieldingFlexibleGangTask("Concurrent marking done multi-threaded"), | |
3690 _collector(collector), | |
3691 _cms_space(cms_space), | |
3692 _perm_space(perm_space), | |
3693 _asynch(asynch), _n_workers(n_workers), _result(true), | |
3694 _workers(workers), _task_queues(task_queues), | |
3695 _term(n_workers, task_queues, _collector, asynch), | |
3696 _bit_map_lock(collector->bitMapLock()) | |
3697 { | |
3698 assert(n_workers <= workers->total_workers(), | |
3699 "Else termination won't work correctly today"); // XXX FIX ME! | |
3700 _requested_size = n_workers; | |
3701 _term.set_task(this); | |
3702 assert(_cms_space->bottom() < _perm_space->bottom(), | |
3703 "Finger incorrectly initialized below"); | |
340
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3704 _restart_addr = _global_finger = _cms_space->bottom(); |
0 | 3705 } |
3706 | |
3707 | |
3708 OopTaskQueueSet* task_queues() { return _task_queues; } | |
3709 | |
3710 OopTaskQueue* work_queue(int i) { return task_queues()->queue(i); } | |
3711 | |
3712 HeapWord** global_finger_addr() { return &_global_finger; } | |
3713 | |
3714 CMSConcMarkingTerminator* terminator() { return &_term; } | |
3715 | |
3716 void work(int i); | |
3717 | |
3718 virtual void coordinator_yield(); // stuff done by coordinator | |
3719 bool result() { return _result; } | |
3720 | |
3721 void reset(HeapWord* ra) { | |
340
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3722 assert(_global_finger >= _cms_space->end(), "Postcondition of ::work(i)"); |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3723 assert(_global_finger >= _perm_space->end(), "Postcondition of ::work(i)"); |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3724 assert(ra < _perm_space->end(), "ra too large"); |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3725 _restart_addr = _global_finger = ra; |
0 | 3726 _term.reset_for_reuse(); |
3727 } | |
3728 | |
3729 static bool get_work_from_overflow_stack(CMSMarkStack* ovflw_stk, | |
3730 OopTaskQueue* work_q); | |
3731 | |
3732 private: | |
3733 void do_scan_and_mark(int i, CompactibleFreeListSpace* sp); | |
3734 void do_work_steal(int i); | |
3735 void bump_global_finger(HeapWord* f); | |
3736 }; | |
3737 | |
3738 void CMSConcMarkingTerminator::yield() { | |
3739 if (ConcurrentMarkSweepThread::should_yield() && | |
3740 !_collector->foregroundGCIsActive() && | |
3741 _yield) { | |
3742 _task->yield(); | |
3743 } else { | |
3744 ParallelTaskTerminator::yield(); | |
3745 } | |
3746 } | |
3747 | |
3748 //////////////////////////////////////////////////////////////// | |
3749 // Concurrent Marking Algorithm Sketch | |
3750 //////////////////////////////////////////////////////////////// | |
3751 // Until all tasks exhausted (both spaces): | |
3752 // -- claim next available chunk | |
3753 // -- bump global finger via CAS | |
3754 // -- find first object that starts in this chunk | |
3755 // and start scanning bitmap from that position | |
3756 // -- scan marked objects for oops | |
3757 // -- CAS-mark target, and if successful: | |
3758 // . if target oop is above global finger (volatile read) | |
3759 // nothing to do | |
3760 // . if target oop is in chunk and above local finger | |
3761 // then nothing to do | |
3762 // . else push on work-queue | |
3763 // -- Deal with possible overflow issues: | |
3764 // . local work-queue overflow causes stuff to be pushed on | |
3765 // global (common) overflow queue | |
3766 // . always first empty local work queue | |
3767 // . then get a batch of oops from global work queue if any | |
3768 // . then do work stealing | |
3769 // -- When all tasks claimed (both spaces) | |
3770 // and local work queue empty, | |
3771 // then in a loop do: | |
3772 // . check global overflow stack; steal a batch of oops and trace | |
3773 // . try to steal from other threads oif GOS is empty | |
3774 // . if neither is available, offer termination | |
3775 // -- Terminate and return result | |
3776 // | |
3777 void CMSConcMarkingTask::work(int i) { | |
3778 elapsedTimer _timer; | |
3779 ResourceMark rm; | |
3780 HandleMark hm; | |
3781 | |
3782 DEBUG_ONLY(_collector->verify_overflow_empty();) | |
3783 | |
3784 // Before we begin work, our work queue should be empty | |
3785 assert(work_queue(i)->size() == 0, "Expected to be empty"); | |
3786 // Scan the bitmap covering _cms_space, tracing through grey objects. | |
3787 _timer.start(); | |
3788 do_scan_and_mark(i, _cms_space); | |
3789 _timer.stop(); | |
3790 if (PrintCMSStatistics != 0) { | |
3791 gclog_or_tty->print_cr("Finished cms space scanning in %dth thread: %3.3f sec", | |
3792 i, _timer.seconds()); // XXX: need xxx/xxx type of notation, two timers | |
3793 } | |
3794 | |
3795 // ... do the same for the _perm_space | |
3796 _timer.reset(); | |
3797 _timer.start(); | |
3798 do_scan_and_mark(i, _perm_space); | |
3799 _timer.stop(); | |
3800 if (PrintCMSStatistics != 0) { | |
3801 gclog_or_tty->print_cr("Finished perm space scanning in %dth thread: %3.3f sec", | |
3802 i, _timer.seconds()); // XXX: need xxx/xxx type of notation, two timers | |
3803 } | |
3804 | |
3805 // ... do work stealing | |
3806 _timer.reset(); | |
3807 _timer.start(); | |
3808 do_work_steal(i); | |
3809 _timer.stop(); | |
3810 if (PrintCMSStatistics != 0) { | |
3811 gclog_or_tty->print_cr("Finished work stealing in %dth thread: %3.3f sec", | |
3812 i, _timer.seconds()); // XXX: need xxx/xxx type of notation, two timers | |
3813 } | |
3814 assert(_collector->_markStack.isEmpty(), "Should have been emptied"); | |
3815 assert(work_queue(i)->size() == 0, "Should have been emptied"); | |
3816 // Note that under the current task protocol, the | |
3817 // following assertion is true even of the spaces | |
3818 // expanded since the completion of the concurrent | |
3819 // marking. XXX This will likely change under a strict | |
3820 // ABORT semantics. | |
3821 assert(_global_finger > _cms_space->end() && | |
3822 _global_finger >= _perm_space->end(), | |
3823 "All tasks have been completed"); | |
3824 DEBUG_ONLY(_collector->verify_overflow_empty();) | |
3825 } | |
3826 | |
3827 void CMSConcMarkingTask::bump_global_finger(HeapWord* f) { | |
3828 HeapWord* read = _global_finger; | |
3829 HeapWord* cur = read; | |
3830 while (f > read) { | |
3831 cur = read; | |
3832 read = (HeapWord*) Atomic::cmpxchg_ptr(f, &_global_finger, cur); | |
3833 if (cur == read) { | |
3834 // our cas succeeded | |
3835 assert(_global_finger >= f, "protocol consistency"); | |
3836 break; | |
3837 } | |
3838 } | |
3839 } | |
3840 | |
3841 // This is really inefficient, and should be redone by | |
3842 // using (not yet available) block-read and -write interfaces to the | |
3843 // stack and the work_queue. XXX FIX ME !!! | |
3844 bool CMSConcMarkingTask::get_work_from_overflow_stack(CMSMarkStack* ovflw_stk, | |
3845 OopTaskQueue* work_q) { | |
3846 // Fast lock-free check | |
3847 if (ovflw_stk->length() == 0) { | |
3848 return false; | |
3849 } | |
3850 assert(work_q->size() == 0, "Shouldn't steal"); | |
3851 MutexLockerEx ml(ovflw_stk->par_lock(), | |
3852 Mutex::_no_safepoint_check_flag); | |
3853 // Grab up to 1/4 the size of the work queue | |
679
cea947c8a988
6819891: ParNew: Fix work queue overflow code to deal correctly with +UseCompressedOops
ysr
parents:
628
diff
changeset
|
3854 size_t num = MIN2((size_t)(work_q->max_elems() - work_q->size())/4, |
0 | 3855 (size_t)ParGCDesiredObjsFromOverflowList); |
3856 num = MIN2(num, ovflw_stk->length()); | |
3857 for (int i = (int) num; i > 0; i--) { | |
3858 oop cur = ovflw_stk->pop(); | |
3859 assert(cur != NULL, "Counted wrong?"); | |
3860 work_q->push(cur); | |
3861 } | |
3862 return num > 0; | |
3863 } | |
3864 | |
3865 void CMSConcMarkingTask::do_scan_and_mark(int i, CompactibleFreeListSpace* sp) { | |
3866 SequentialSubTasksDone* pst = sp->conc_par_seq_tasks(); | |
3867 int n_tasks = pst->n_tasks(); | |
3868 // We allow that there may be no tasks to do here because | |
3869 // we are restarting after a stack overflow. | |
340
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3870 assert(pst->valid() || n_tasks == 0, "Uninitialized use?"); |
0 | 3871 int nth_task = 0; |
3872 | |
340
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3873 HeapWord* aligned_start = sp->bottom(); |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3874 if (sp->used_region().contains(_restart_addr)) { |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3875 // Align down to a card boundary for the start of 0th task |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3876 // for this space. |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3877 aligned_start = |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3878 (HeapWord*)align_size_down((uintptr_t)_restart_addr, |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3879 CardTableModRefBS::card_size); |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3880 } |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3881 |
0 | 3882 size_t chunk_size = sp->marking_task_size(); |
3883 while (!pst->is_task_claimed(/* reference */ nth_task)) { | |
3884 // Having claimed the nth task in this space, | |
3885 // compute the chunk that it corresponds to: | |
340
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3886 MemRegion span = MemRegion(aligned_start + nth_task*chunk_size, |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3887 aligned_start + (nth_task+1)*chunk_size); |
0 | 3888 // Try and bump the global finger via a CAS; |
3889 // note that we need to do the global finger bump | |
3890 // _before_ taking the intersection below, because | |
3891 // the task corresponding to that region will be | |
3892 // deemed done even if the used_region() expands | |
3893 // because of allocation -- as it almost certainly will | |
3894 // during start-up while the threads yield in the | |
3895 // closure below. | |
3896 HeapWord* finger = span.end(); | |
3897 bump_global_finger(finger); // atomically | |
3898 // There are null tasks here corresponding to chunks | |
3899 // beyond the "top" address of the space. | |
3900 span = span.intersection(sp->used_region()); | |
3901 if (!span.is_empty()) { // Non-null task | |
340
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3902 HeapWord* prev_obj; |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3903 assert(!span.contains(_restart_addr) || nth_task == 0, |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3904 "Inconsistency"); |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3905 if (nth_task == 0) { |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3906 // For the 0th task, we'll not need to compute a block_start. |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3907 if (span.contains(_restart_addr)) { |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3908 // In the case of a restart because of stack overflow, |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3909 // we might additionally skip a chunk prefix. |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3910 prev_obj = _restart_addr; |
0 | 3911 } else { |
340
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3912 prev_obj = span.start(); |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3913 } |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3914 } else { |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3915 // We want to skip the first object because |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3916 // the protocol is to scan any object in its entirety |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3917 // that _starts_ in this span; a fortiori, any |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3918 // object starting in an earlier span is scanned |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3919 // as part of an earlier claimed task. |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3920 // Below we use the "careful" version of block_start |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3921 // so we do not try to navigate uninitialized objects. |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3922 prev_obj = sp->block_start_careful(span.start()); |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3923 // Below we use a variant of block_size that uses the |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3924 // Printezis bits to avoid waiting for allocated |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3925 // objects to become initialized/parsable. |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3926 while (prev_obj < span.start()) { |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3927 size_t sz = sp->block_size_no_stall(prev_obj, _collector); |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3928 if (sz > 0) { |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3929 prev_obj += sz; |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3930 } else { |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3931 // In this case we may end up doing a bit of redundant |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3932 // scanning, but that appears unavoidable, short of |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3933 // locking the free list locks; see bug 6324141. |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3934 break; |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3935 } |
0 | 3936 } |
3937 } | |
3938 if (prev_obj < span.end()) { | |
3939 MemRegion my_span = MemRegion(prev_obj, span.end()); | |
3940 // Do the marking work within a non-empty span -- | |
3941 // the last argument to the constructor indicates whether the | |
3942 // iteration should be incremental with periodic yields. | |
3943 Par_MarkFromRootsClosure cl(this, _collector, my_span, | |
3944 &_collector->_markBitMap, | |
3945 work_queue(i), | |
3946 &_collector->_markStack, | |
3947 &_collector->_revisitStack, | |
3948 _asynch); | |
3949 _collector->_markBitMap.iterate(&cl, my_span.start(), my_span.end()); | |
3950 } // else nothing to do for this task | |
3951 } // else nothing to do for this task | |
3952 } | |
3953 // We'd be tempted to assert here that since there are no | |
3954 // more tasks left to claim in this space, the global_finger | |
3955 // must exceed space->top() and a fortiori space->end(). However, | |
3956 // that would not quite be correct because the bumping of | |
3957 // global_finger occurs strictly after the claiming of a task, | |
3958 // so by the time we reach here the global finger may not yet | |
3959 // have been bumped up by the thread that claimed the last | |
3960 // task. | |
3961 pst->all_tasks_completed(); | |
3962 } | |
3963 | |
935 | 3964 class Par_ConcMarkingClosure: public Par_KlassRememberingOopClosure { |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
3965 private: |
0 | 3966 MemRegion _span; |
3967 CMSBitMap* _bit_map; | |
3968 CMSMarkStack* _overflow_stack; | |
3969 OopTaskQueue* _work_queue; | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
3970 protected: |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
3971 DO_OOP_WORK_DEFN |
0 | 3972 public: |
3973 Par_ConcMarkingClosure(CMSCollector* collector, OopTaskQueue* work_queue, | |
935 | 3974 CMSBitMap* bit_map, CMSMarkStack* overflow_stack, |
3975 CMSMarkStack* revisit_stack): | |
3976 Par_KlassRememberingOopClosure(collector, NULL, revisit_stack), | |
0 | 3977 _span(_collector->_span), |
3978 _work_queue(work_queue), | |
3979 _bit_map(bit_map), | |
935 | 3980 _overflow_stack(overflow_stack) |
3981 { } | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
3982 virtual void do_oop(oop* p); |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
3983 virtual void do_oop(narrowOop* p); |
0 | 3984 void trim_queue(size_t max); |
3985 void handle_stack_overflow(HeapWord* lost); | |
3986 }; | |
3987 | |
340
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3988 // Grey object scanning during work stealing phase -- |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3989 // the salient assumption here is that any references |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3990 // that are in these stolen objects being scanned must |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3991 // already have been initialized (else they would not have |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3992 // been published), so we do not need to check for |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3993 // uninitialized objects before pushing here. |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
3994 void Par_ConcMarkingClosure::do_oop(oop obj) { |
340
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
3995 assert(obj->is_oop_or_null(true), "expected an oop or NULL"); |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
3996 HeapWord* addr = (HeapWord*)obj; |
0 | 3997 // Check if oop points into the CMS generation |
3998 // and is not marked | |
3999 if (_span.contains(addr) && !_bit_map->isMarked(addr)) { | |
4000 // a white object ... | |
4001 // If we manage to "claim" the object, by being the | |
4002 // first thread to mark it, then we push it on our | |
4003 // marking stack | |
4004 if (_bit_map->par_mark(addr)) { // ... now grey | |
4005 // push on work queue (grey set) | |
4006 bool simulate_overflow = false; | |
4007 NOT_PRODUCT( | |
4008 if (CMSMarkStackOverflowALot && | |
4009 _collector->simulate_overflow()) { | |
4010 // simulate a stack overflow | |
4011 simulate_overflow = true; | |
4012 } | |
4013 ) | |
4014 if (simulate_overflow || | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
4015 !(_work_queue->push(obj) || _overflow_stack->par_push(obj))) { |
0 | 4016 // stack overflow |
4017 if (PrintCMSStatistics != 0) { | |
4018 gclog_or_tty->print_cr("CMS marking stack overflow (benign) at " | |
4019 SIZE_FORMAT, _overflow_stack->capacity()); | |
4020 } | |
4021 // We cannot assert that the overflow stack is full because | |
4022 // it may have been emptied since. | |
4023 assert(simulate_overflow || | |
4024 _work_queue->size() == _work_queue->max_elems(), | |
4025 "Else push should have succeeded"); | |
4026 handle_stack_overflow(addr); | |
4027 } | |
4028 } // Else, some other thread got there first | |
4029 } | |
4030 } | |
4031 | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
4032 void Par_ConcMarkingClosure::do_oop(oop* p) { Par_ConcMarkingClosure::do_oop_work(p); } |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
4033 void Par_ConcMarkingClosure::do_oop(narrowOop* p) { Par_ConcMarkingClosure::do_oop_work(p); } |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
4034 |
0 | 4035 void Par_ConcMarkingClosure::trim_queue(size_t max) { |
4036 while (_work_queue->size() > max) { | |
4037 oop new_oop; | |
4038 if (_work_queue->pop_local(new_oop)) { | |
4039 assert(new_oop->is_oop(), "Should be an oop"); | |
4040 assert(_bit_map->isMarked((HeapWord*)new_oop), "Grey object"); | |
4041 assert(_span.contains((HeapWord*)new_oop), "Not in span"); | |
4042 assert(new_oop->is_parsable(), "Should be parsable"); | |
4043 new_oop->oop_iterate(this); // do_oop() above | |
4044 } | |
4045 } | |
4046 } | |
4047 | |
4048 // Upon stack overflow, we discard (part of) the stack, | |
4049 // remembering the least address amongst those discarded | |
4050 // in CMSCollector's _restart_address. | |
4051 void Par_ConcMarkingClosure::handle_stack_overflow(HeapWord* lost) { | |
4052 // We need to do this under a mutex to prevent other | |
340
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
4053 // workers from interfering with the work done below. |
0 | 4054 MutexLockerEx ml(_overflow_stack->par_lock(), |
4055 Mutex::_no_safepoint_check_flag); | |
4056 // Remember the least grey address discarded | |
4057 HeapWord* ra = (HeapWord*)_overflow_stack->least_value(lost); | |
4058 _collector->lower_restart_addr(ra); | |
4059 _overflow_stack->reset(); // discard stack contents | |
4060 _overflow_stack->expand(); // expand the stack if possible | |
4061 } | |
4062 | |
4063 | |
4064 void CMSConcMarkingTask::do_work_steal(int i) { | |
4065 OopTaskQueue* work_q = work_queue(i); | |
4066 oop obj_to_scan; | |
4067 CMSBitMap* bm = &(_collector->_markBitMap); | |
4068 CMSMarkStack* ovflw = &(_collector->_markStack); | |
935 | 4069 CMSMarkStack* revisit = &(_collector->_revisitStack); |
0 | 4070 int* seed = _collector->hash_seed(i); |
935 | 4071 Par_ConcMarkingClosure cl(_collector, work_q, bm, ovflw, revisit); |
0 | 4072 while (true) { |
4073 cl.trim_queue(0); | |
4074 assert(work_q->size() == 0, "Should have been emptied above"); | |
4075 if (get_work_from_overflow_stack(ovflw, work_q)) { | |
4076 // Can't assert below because the work obtained from the | |
4077 // overflow stack may already have been stolen from us. | |
4078 // assert(work_q->size() > 0, "Work from overflow stack"); | |
4079 continue; | |
4080 } else if (task_queues()->steal(i, seed, /* reference */ obj_to_scan)) { | |
4081 assert(obj_to_scan->is_oop(), "Should be an oop"); | |
4082 assert(bm->isMarked((HeapWord*)obj_to_scan), "Grey object"); | |
4083 obj_to_scan->oop_iterate(&cl); | |
4084 } else if (terminator()->offer_termination()) { | |
4085 assert(work_q->size() == 0, "Impossible!"); | |
4086 break; | |
4087 } | |
4088 } | |
4089 } | |
4090 | |
4091 // This is run by the CMS (coordinator) thread. | |
4092 void CMSConcMarkingTask::coordinator_yield() { | |
4093 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
4094 "CMS thread should hold CMS token"); | |
935 | 4095 DEBUG_ONLY(RememberKlassesChecker mux(false);) |
0 | 4096 // First give up the locks, then yield, then re-lock |
4097 // We should probably use a constructor/destructor idiom to | |
4098 // do this unlock/lock or modify the MutexUnlocker class to | |
4099 // serve our purpose. XXX | |
4100 assert_lock_strong(_bit_map_lock); | |
4101 _bit_map_lock->unlock(); | |
4102 ConcurrentMarkSweepThread::desynchronize(true); | |
4103 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
4104 _collector->stopTimer(); | |
4105 if (PrintCMSStatistics != 0) { | |
4106 _collector->incrementYields(); | |
4107 } | |
4108 _collector->icms_wait(); | |
4109 | |
4110 // It is possible for whichever thread initiated the yield request | |
4111 // not to get a chance to wake up and take the bitmap lock between | |
4112 // this thread releasing it and reacquiring it. So, while the | |
4113 // should_yield() flag is on, let's sleep for a bit to give the | |
4114 // other thread a chance to wake up. The limit imposed on the number | |
4115 // of iterations is defensive, to avoid any unforseen circumstances | |
4116 // putting us into an infinite loop. Since it's always been this | |
4117 // (coordinator_yield()) method that was observed to cause the | |
4118 // problem, we are using a parameter (CMSCoordinatorYieldSleepCount) | |
4119 // which is by default non-zero. For the other seven methods that | |
4120 // also perform the yield operation, as are using a different | |
4121 // parameter (CMSYieldSleepCount) which is by default zero. This way we | |
4122 // can enable the sleeping for those methods too, if necessary. | |
4123 // See 6442774. | |
4124 // | |
4125 // We really need to reconsider the synchronization between the GC | |
4126 // thread and the yield-requesting threads in the future and we | |
4127 // should really use wait/notify, which is the recommended | |
4128 // way of doing this type of interaction. Additionally, we should | |
4129 // consolidate the eight methods that do the yield operation and they | |
4130 // are almost identical into one for better maintenability and | |
4131 // readability. See 6445193. | |
4132 // | |
4133 // Tony 2006.06.29 | |
4134 for (unsigned i = 0; i < CMSCoordinatorYieldSleepCount && | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
4135 ConcurrentMarkSweepThread::should_yield() && |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
4136 !CMSCollector::foregroundGCIsActive(); ++i) { |
0 | 4137 os::sleep(Thread::current(), 1, false); |
4138 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
4139 } | |
4140 | |
4141 ConcurrentMarkSweepThread::synchronize(true); | |
4142 _bit_map_lock->lock_without_safepoint_check(); | |
4143 _collector->startTimer(); | |
4144 } | |
4145 | |
4146 bool CMSCollector::do_marking_mt(bool asynch) { | |
1284 | 4147 assert(ConcGCThreads > 0 && conc_workers() != NULL, "precondition"); |
0 | 4148 // In the future this would be determined ergonomically, based |
4149 // on #cpu's, # active mutator threads (and load), and mutation rate. | |
1284 | 4150 int num_workers = ConcGCThreads; |
0 | 4151 |
4152 CompactibleFreeListSpace* cms_space = _cmsGen->cmsSpace(); | |
4153 CompactibleFreeListSpace* perm_space = _permGen->cmsSpace(); | |
4154 | |
4155 CMSConcMarkingTask tsk(this, cms_space, perm_space, | |
4156 asynch, num_workers /* number requested XXX */, | |
4157 conc_workers(), task_queues()); | |
4158 | |
4159 // Since the actual number of workers we get may be different | |
4160 // from the number we requested above, do we need to do anything different | |
4161 // below? In particular, may be we need to subclass the SequantialSubTasksDone | |
4162 // class?? XXX | |
4163 cms_space ->initialize_sequential_subtasks_for_marking(num_workers); | |
4164 perm_space->initialize_sequential_subtasks_for_marking(num_workers); | |
4165 | |
4166 // Refs discovery is already non-atomic. | |
4167 assert(!ref_processor()->discovery_is_atomic(), "Should be non-atomic"); | |
4168 // Mutate the Refs discovery so it is MT during the | |
4169 // multi-threaded marking phase. | |
4170 ReferenceProcessorMTMutator mt(ref_processor(), num_workers > 1); | |
1190
4788266644c1
6895236: CMS: cmsOopClosures.inline.hpp:43 assert(..., "Should remember klasses in this context")
jmasa
parents:
1145
diff
changeset
|
4171 DEBUG_ONLY(RememberKlassesChecker cmx(should_unload_classes());) |
0 | 4172 conc_workers()->start_task(&tsk); |
4173 while (tsk.yielded()) { | |
4174 tsk.coordinator_yield(); | |
4175 conc_workers()->continue_task(&tsk); | |
4176 } | |
4177 // If the task was aborted, _restart_addr will be non-NULL | |
4178 assert(tsk.completed() || _restart_addr != NULL, "Inconsistency"); | |
4179 while (_restart_addr != NULL) { | |
4180 // XXX For now we do not make use of ABORTED state and have not | |
4181 // yet implemented the right abort semantics (even in the original | |
4182 // single-threaded CMS case). That needs some more investigation | |
4183 // and is deferred for now; see CR# TBF. 07252005YSR. XXX | |
4184 assert(!CMSAbortSemantics || tsk.aborted(), "Inconsistency"); | |
4185 // If _restart_addr is non-NULL, a marking stack overflow | |
605 | 4186 // occurred; we need to do a fresh marking iteration from the |
0 | 4187 // indicated restart address. |
4188 if (_foregroundGCIsActive && asynch) { | |
4189 // We may be running into repeated stack overflows, having | |
4190 // reached the limit of the stack size, while making very | |
4191 // slow forward progress. It may be best to bail out and | |
4192 // let the foreground collector do its job. | |
4193 // Clear _restart_addr, so that foreground GC | |
4194 // works from scratch. This avoids the headache of | |
4195 // a "rescan" which would otherwise be needed because | |
4196 // of the dirty mod union table & card table. | |
4197 _restart_addr = NULL; | |
4198 return false; | |
4199 } | |
4200 // Adjust the task to restart from _restart_addr | |
4201 tsk.reset(_restart_addr); | |
4202 cms_space ->initialize_sequential_subtasks_for_marking(num_workers, | |
4203 _restart_addr); | |
4204 perm_space->initialize_sequential_subtasks_for_marking(num_workers, | |
4205 _restart_addr); | |
4206 _restart_addr = NULL; | |
4207 // Get the workers going again | |
4208 conc_workers()->start_task(&tsk); | |
4209 while (tsk.yielded()) { | |
4210 tsk.coordinator_yield(); | |
4211 conc_workers()->continue_task(&tsk); | |
4212 } | |
4213 } | |
4214 assert(tsk.completed(), "Inconsistency"); | |
4215 assert(tsk.result() == true, "Inconsistency"); | |
4216 return true; | |
4217 } | |
4218 | |
4219 bool CMSCollector::do_marking_st(bool asynch) { | |
4220 ResourceMark rm; | |
4221 HandleMark hm; | |
4222 | |
4223 MarkFromRootsClosure markFromRootsClosure(this, _span, &_markBitMap, | |
4224 &_markStack, &_revisitStack, CMSYield && asynch); | |
4225 // the last argument to iterate indicates whether the iteration | |
4226 // should be incremental with periodic yields. | |
4227 _markBitMap.iterate(&markFromRootsClosure); | |
4228 // If _restart_addr is non-NULL, a marking stack overflow | |
605 | 4229 // occurred; we need to do a fresh iteration from the |
0 | 4230 // indicated restart address. |
4231 while (_restart_addr != NULL) { | |
4232 if (_foregroundGCIsActive && asynch) { | |
4233 // We may be running into repeated stack overflows, having | |
4234 // reached the limit of the stack size, while making very | |
4235 // slow forward progress. It may be best to bail out and | |
4236 // let the foreground collector do its job. | |
4237 // Clear _restart_addr, so that foreground GC | |
4238 // works from scratch. This avoids the headache of | |
4239 // a "rescan" which would otherwise be needed because | |
4240 // of the dirty mod union table & card table. | |
4241 _restart_addr = NULL; | |
4242 return false; // indicating failure to complete marking | |
4243 } | |
4244 // Deal with stack overflow: | |
4245 // we restart marking from _restart_addr | |
4246 HeapWord* ra = _restart_addr; | |
4247 markFromRootsClosure.reset(ra); | |
4248 _restart_addr = NULL; | |
4249 _markBitMap.iterate(&markFromRootsClosure, ra, _span.end()); | |
4250 } | |
4251 return true; | |
4252 } | |
4253 | |
4254 void CMSCollector::preclean() { | |
4255 check_correct_thread_executing(); | |
4256 assert(Thread::current()->is_ConcurrentGC_thread(), "Wrong thread"); | |
4257 verify_work_stacks_empty(); | |
4258 verify_overflow_empty(); | |
4259 _abort_preclean = false; | |
4260 if (CMSPrecleaningEnabled) { | |
4261 _eden_chunk_index = 0; | |
4262 size_t used = get_eden_used(); | |
4263 size_t capacity = get_eden_capacity(); | |
4264 // Don't start sampling unless we will get sufficiently | |
4265 // many samples. | |
4266 if (used < (capacity/(CMSScheduleRemarkSamplingRatio * 100) | |
4267 * CMSScheduleRemarkEdenPenetration)) { | |
4268 _start_sampling = true; | |
4269 } else { | |
4270 _start_sampling = false; | |
4271 } | |
4272 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
4273 CMSPhaseAccounting pa(this, "preclean", !PrintGCDetails); | |
4274 preclean_work(CMSPrecleanRefLists1, CMSPrecleanSurvivors1); | |
4275 } | |
4276 CMSTokenSync x(true); // is cms thread | |
4277 if (CMSPrecleaningEnabled) { | |
4278 sample_eden(); | |
4279 _collectorState = AbortablePreclean; | |
4280 } else { | |
4281 _collectorState = FinalMarking; | |
4282 } | |
4283 verify_work_stacks_empty(); | |
4284 verify_overflow_empty(); | |
4285 } | |
4286 | |
4287 // Try and schedule the remark such that young gen | |
4288 // occupancy is CMSScheduleRemarkEdenPenetration %. | |
4289 void CMSCollector::abortable_preclean() { | |
4290 check_correct_thread_executing(); | |
4291 assert(CMSPrecleaningEnabled, "Inconsistent control state"); | |
4292 assert(_collectorState == AbortablePreclean, "Inconsistent control state"); | |
4293 | |
4294 // If Eden's current occupancy is below this threshold, | |
4295 // immediately schedule the remark; else preclean | |
4296 // past the next scavenge in an effort to | |
4297 // schedule the pause as described avove. By choosing | |
4298 // CMSScheduleRemarkEdenSizeThreshold >= max eden size | |
4299 // we will never do an actual abortable preclean cycle. | |
4300 if (get_eden_used() > CMSScheduleRemarkEdenSizeThreshold) { | |
4301 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
4302 CMSPhaseAccounting pa(this, "abortable-preclean", !PrintGCDetails); | |
4303 // We need more smarts in the abortable preclean | |
4304 // loop below to deal with cases where allocation | |
4305 // in young gen is very very slow, and our precleaning | |
4306 // is running a losing race against a horde of | |
4307 // mutators intent on flooding us with CMS updates | |
4308 // (dirty cards). | |
4309 // One, admittedly dumb, strategy is to give up | |
4310 // after a certain number of abortable precleaning loops | |
4311 // or after a certain maximum time. We want to make | |
4312 // this smarter in the next iteration. | |
4313 // XXX FIX ME!!! YSR | |
4314 size_t loops = 0, workdone = 0, cumworkdone = 0, waited = 0; | |
4315 while (!(should_abort_preclean() || | |
4316 ConcurrentMarkSweepThread::should_terminate())) { | |
4317 workdone = preclean_work(CMSPrecleanRefLists2, CMSPrecleanSurvivors2); | |
4318 cumworkdone += workdone; | |
4319 loops++; | |
4320 // Voluntarily terminate abortable preclean phase if we have | |
4321 // been at it for too long. | |
4322 if ((CMSMaxAbortablePrecleanLoops != 0) && | |
4323 loops >= CMSMaxAbortablePrecleanLoops) { | |
4324 if (PrintGCDetails) { | |
4325 gclog_or_tty->print(" CMS: abort preclean due to loops "); | |
4326 } | |
4327 break; | |
4328 } | |
4329 if (pa.wallclock_millis() > CMSMaxAbortablePrecleanTime) { | |
4330 if (PrintGCDetails) { | |
4331 gclog_or_tty->print(" CMS: abort preclean due to time "); | |
4332 } | |
4333 break; | |
4334 } | |
4335 // If we are doing little work each iteration, we should | |
4336 // take a short break. | |
4337 if (workdone < CMSAbortablePrecleanMinWorkPerIteration) { | |
4338 // Sleep for some time, waiting for work to accumulate | |
4339 stopTimer(); | |
4340 cmsThread()->wait_on_cms_lock(CMSAbortablePrecleanWaitMillis); | |
4341 startTimer(); | |
4342 waited++; | |
4343 } | |
4344 } | |
4345 if (PrintCMSStatistics > 0) { | |
4346 gclog_or_tty->print(" [%d iterations, %d waits, %d cards)] ", | |
4347 loops, waited, cumworkdone); | |
4348 } | |
4349 } | |
4350 CMSTokenSync x(true); // is cms thread | |
4351 if (_collectorState != Idling) { | |
4352 assert(_collectorState == AbortablePreclean, | |
4353 "Spontaneous state transition?"); | |
4354 _collectorState = FinalMarking; | |
4355 } // Else, a foreground collection completed this CMS cycle. | |
4356 return; | |
4357 } | |
4358 | |
4359 // Respond to an Eden sampling opportunity | |
4360 void CMSCollector::sample_eden() { | |
4361 // Make sure a young gc cannot sneak in between our | |
4362 // reading and recording of a sample. | |
4363 assert(Thread::current()->is_ConcurrentGC_thread(), | |
4364 "Only the cms thread may collect Eden samples"); | |
4365 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
4366 "Should collect samples while holding CMS token"); | |
4367 if (!_start_sampling) { | |
4368 return; | |
4369 } | |
4370 if (_eden_chunk_array) { | |
4371 if (_eden_chunk_index < _eden_chunk_capacity) { | |
4372 _eden_chunk_array[_eden_chunk_index] = *_top_addr; // take sample | |
4373 assert(_eden_chunk_array[_eden_chunk_index] <= *_end_addr, | |
4374 "Unexpected state of Eden"); | |
4375 // We'd like to check that what we just sampled is an oop-start address; | |
4376 // however, we cannot do that here since the object may not yet have been | |
4377 // initialized. So we'll instead do the check when we _use_ this sample | |
4378 // later. | |
4379 if (_eden_chunk_index == 0 || | |
4380 (pointer_delta(_eden_chunk_array[_eden_chunk_index], | |
4381 _eden_chunk_array[_eden_chunk_index-1]) | |
4382 >= CMSSamplingGrain)) { | |
4383 _eden_chunk_index++; // commit sample | |
4384 } | |
4385 } | |
4386 } | |
4387 if ((_collectorState == AbortablePreclean) && !_abort_preclean) { | |
4388 size_t used = get_eden_used(); | |
4389 size_t capacity = get_eden_capacity(); | |
4390 assert(used <= capacity, "Unexpected state of Eden"); | |
4391 if (used > (capacity/100 * CMSScheduleRemarkEdenPenetration)) { | |
4392 _abort_preclean = true; | |
4393 } | |
4394 } | |
4395 } | |
4396 | |
4397 | |
4398 size_t CMSCollector::preclean_work(bool clean_refs, bool clean_survivor) { | |
4399 assert(_collectorState == Precleaning || | |
4400 _collectorState == AbortablePreclean, "incorrect state"); | |
4401 ResourceMark rm; | |
4402 HandleMark hm; | |
4403 // Do one pass of scrubbing the discovered reference lists | |
4404 // to remove any reference objects with strongly-reachable | |
4405 // referents. | |
4406 if (clean_refs) { | |
4407 ReferenceProcessor* rp = ref_processor(); | |
4408 CMSPrecleanRefsYieldClosure yield_cl(this); | |
4409 assert(rp->span().equals(_span), "Spans should be equal"); | |
4410 CMSKeepAliveClosure keep_alive(this, _span, &_markBitMap, | |
935 | 4411 &_markStack, &_revisitStack, |
4412 true /* preclean */); | |
0 | 4413 CMSDrainMarkingStackClosure complete_trace(this, |
452
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
4414 _span, &_markBitMap, &_markStack, |
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
4415 &keep_alive, true /* preclean */); |
0 | 4416 |
4417 // We don't want this step to interfere with a young | |
4418 // collection because we don't want to take CPU | |
4419 // or memory bandwidth away from the young GC threads | |
4420 // (which may be as many as there are CPUs). | |
4421 // Note that we don't need to protect ourselves from | |
4422 // interference with mutators because they can't | |
4423 // manipulate the discovered reference lists nor affect | |
4424 // the computed reachability of the referents, the | |
4425 // only properties manipulated by the precleaning | |
4426 // of these reference lists. | |
4427 stopTimer(); | |
4428 CMSTokenSyncWithLocks x(true /* is cms thread */, | |
4429 bitMapLock()); | |
4430 startTimer(); | |
4431 sample_eden(); | |
935 | 4432 |
0 | 4433 // The following will yield to allow foreground |
4434 // collection to proceed promptly. XXX YSR: | |
4435 // The code in this method may need further | |
4436 // tweaking for better performance and some restructuring | |
4437 // for cleaner interfaces. | |
4438 rp->preclean_discovered_references( | |
4439 rp->is_alive_non_header(), &keep_alive, &complete_trace, | |
1190
4788266644c1
6895236: CMS: cmsOopClosures.inline.hpp:43 assert(..., "Should remember klasses in this context")
jmasa
parents:
1145
diff
changeset
|
4440 &yield_cl, should_unload_classes()); |
0 | 4441 } |
4442 | |
4443 if (clean_survivor) { // preclean the active survivor space(s) | |
4444 assert(_young_gen->kind() == Generation::DefNew || | |
4445 _young_gen->kind() == Generation::ParNew || | |
4446 _young_gen->kind() == Generation::ASParNew, | |
4447 "incorrect type for cast"); | |
4448 DefNewGeneration* dng = (DefNewGeneration*)_young_gen; | |
4449 PushAndMarkClosure pam_cl(this, _span, ref_processor(), | |
4450 &_markBitMap, &_modUnionTable, | |
4451 &_markStack, &_revisitStack, | |
4452 true /* precleaning phase */); | |
4453 stopTimer(); | |
4454 CMSTokenSyncWithLocks ts(true /* is cms thread */, | |
4455 bitMapLock()); | |
4456 startTimer(); | |
4457 unsigned int before_count = | |
4458 GenCollectedHeap::heap()->total_collections(); | |
4459 SurvivorSpacePrecleanClosure | |
4460 sss_cl(this, _span, &_markBitMap, &_markStack, | |
4461 &pam_cl, before_count, CMSYield); | |
1190
4788266644c1
6895236: CMS: cmsOopClosures.inline.hpp:43 assert(..., "Should remember klasses in this context")
jmasa
parents:
1145
diff
changeset
|
4462 DEBUG_ONLY(RememberKlassesChecker mx(should_unload_classes());) |
0 | 4463 dng->from()->object_iterate_careful(&sss_cl); |
4464 dng->to()->object_iterate_careful(&sss_cl); | |
4465 } | |
4466 MarkRefsIntoAndScanClosure | |
4467 mrias_cl(_span, ref_processor(), &_markBitMap, &_modUnionTable, | |
4468 &_markStack, &_revisitStack, this, CMSYield, | |
4469 true /* precleaning phase */); | |
4470 // CAUTION: The following closure has persistent state that may need to | |
4471 // be reset upon a decrease in the sequence of addresses it | |
4472 // processes. | |
4473 ScanMarkedObjectsAgainCarefullyClosure | |
4474 smoac_cl(this, _span, | |
4475 &_markBitMap, &_markStack, &_revisitStack, &mrias_cl, CMSYield); | |
4476 | |
4477 // Preclean dirty cards in ModUnionTable and CardTable using | |
4478 // appropriate convergence criterion; | |
4479 // repeat CMSPrecleanIter times unless we find that | |
4480 // we are losing. | |
4481 assert(CMSPrecleanIter < 10, "CMSPrecleanIter is too large"); | |
4482 assert(CMSPrecleanNumerator < CMSPrecleanDenominator, | |
4483 "Bad convergence multiplier"); | |
4484 assert(CMSPrecleanThreshold >= 100, | |
4485 "Unreasonably low CMSPrecleanThreshold"); | |
4486 | |
4487 size_t numIter, cumNumCards, lastNumCards, curNumCards; | |
4488 for (numIter = 0, cumNumCards = lastNumCards = curNumCards = 0; | |
4489 numIter < CMSPrecleanIter; | |
4490 numIter++, lastNumCards = curNumCards, cumNumCards += curNumCards) { | |
4491 curNumCards = preclean_mod_union_table(_cmsGen, &smoac_cl); | |
4492 if (CMSPermGenPrecleaningEnabled) { | |
4493 curNumCards += preclean_mod_union_table(_permGen, &smoac_cl); | |
4494 } | |
4495 if (Verbose && PrintGCDetails) { | |
4496 gclog_or_tty->print(" (modUnionTable: %d cards)", curNumCards); | |
4497 } | |
4498 // Either there are very few dirty cards, so re-mark | |
4499 // pause will be small anyway, or our pre-cleaning isn't | |
4500 // that much faster than the rate at which cards are being | |
4501 // dirtied, so we might as well stop and re-mark since | |
4502 // precleaning won't improve our re-mark time by much. | |
4503 if (curNumCards <= CMSPrecleanThreshold || | |
4504 (numIter > 0 && | |
4505 (curNumCards * CMSPrecleanDenominator > | |
4506 lastNumCards * CMSPrecleanNumerator))) { | |
4507 numIter++; | |
4508 cumNumCards += curNumCards; | |
4509 break; | |
4510 } | |
4511 } | |
4512 curNumCards = preclean_card_table(_cmsGen, &smoac_cl); | |
4513 if (CMSPermGenPrecleaningEnabled) { | |
4514 curNumCards += preclean_card_table(_permGen, &smoac_cl); | |
4515 } | |
4516 cumNumCards += curNumCards; | |
4517 if (PrintGCDetails && PrintCMSStatistics != 0) { | |
4518 gclog_or_tty->print_cr(" (cardTable: %d cards, re-scanned %d cards, %d iterations)", | |
4519 curNumCards, cumNumCards, numIter); | |
4520 } | |
4521 return cumNumCards; // as a measure of useful work done | |
4522 } | |
4523 | |
4524 // PRECLEANING NOTES: | |
4525 // Precleaning involves: | |
4526 // . reading the bits of the modUnionTable and clearing the set bits. | |
4527 // . For the cards corresponding to the set bits, we scan the | |
4528 // objects on those cards. This means we need the free_list_lock | |
4529 // so that we can safely iterate over the CMS space when scanning | |
4530 // for oops. | |
4531 // . When we scan the objects, we'll be both reading and setting | |
4532 // marks in the marking bit map, so we'll need the marking bit map. | |
4533 // . For protecting _collector_state transitions, we take the CGC_lock. | |
4534 // Note that any races in the reading of of card table entries by the | |
4535 // CMS thread on the one hand and the clearing of those entries by the | |
4536 // VM thread or the setting of those entries by the mutator threads on the | |
4537 // other are quite benign. However, for efficiency it makes sense to keep | |
4538 // the VM thread from racing with the CMS thread while the latter is | |
4539 // dirty card info to the modUnionTable. We therefore also use the | |
4540 // CGC_lock to protect the reading of the card table and the mod union | |
4541 // table by the CM thread. | |
4542 // . We run concurrently with mutator updates, so scanning | |
4543 // needs to be done carefully -- we should not try to scan | |
4544 // potentially uninitialized objects. | |
4545 // | |
4546 // Locking strategy: While holding the CGC_lock, we scan over and | |
4547 // reset a maximal dirty range of the mod union / card tables, then lock | |
4548 // the free_list_lock and bitmap lock to do a full marking, then | |
4549 // release these locks; and repeat the cycle. This allows for a | |
4550 // certain amount of fairness in the sharing of these locks between | |
4551 // the CMS collector on the one hand, and the VM thread and the | |
4552 // mutators on the other. | |
4553 | |
4554 // NOTE: preclean_mod_union_table() and preclean_card_table() | |
4555 // further below are largely identical; if you need to modify | |
4556 // one of these methods, please check the other method too. | |
4557 | |
4558 size_t CMSCollector::preclean_mod_union_table( | |
4559 ConcurrentMarkSweepGeneration* gen, | |
4560 ScanMarkedObjectsAgainCarefullyClosure* cl) { | |
4561 verify_work_stacks_empty(); | |
4562 verify_overflow_empty(); | |
4563 | |
935 | 4564 // Turn off checking for this method but turn it back on |
4565 // selectively. There are yield points in this method | |
4566 // but it is difficult to turn the checking off just around | |
4567 // the yield points. It is simpler to selectively turn | |
4568 // it on. | |
4569 DEBUG_ONLY(RememberKlassesChecker mux(false);) | |
4570 | |
0 | 4571 // strategy: starting with the first card, accumulate contiguous |
4572 // ranges of dirty cards; clear these cards, then scan the region | |
4573 // covered by these cards. | |
4574 | |
4575 // Since all of the MUT is committed ahead, we can just use | |
4576 // that, in case the generations expand while we are precleaning. | |
4577 // It might also be fine to just use the committed part of the | |
4578 // generation, but we might potentially miss cards when the | |
4579 // generation is rapidly expanding while we are in the midst | |
4580 // of precleaning. | |
4581 HeapWord* startAddr = gen->reserved().start(); | |
4582 HeapWord* endAddr = gen->reserved().end(); | |
4583 | |
4584 cl->setFreelistLock(gen->freelistLock()); // needed for yielding | |
4585 | |
4586 size_t numDirtyCards, cumNumDirtyCards; | |
4587 HeapWord *nextAddr, *lastAddr; | |
4588 for (cumNumDirtyCards = numDirtyCards = 0, | |
4589 nextAddr = lastAddr = startAddr; | |
4590 nextAddr < endAddr; | |
4591 nextAddr = lastAddr, cumNumDirtyCards += numDirtyCards) { | |
4592 | |
4593 ResourceMark rm; | |
4594 HandleMark hm; | |
4595 | |
4596 MemRegion dirtyRegion; | |
4597 { | |
4598 stopTimer(); | |
935 | 4599 // Potential yield point |
0 | 4600 CMSTokenSync ts(true); |
4601 startTimer(); | |
4602 sample_eden(); | |
4603 // Get dirty region starting at nextOffset (inclusive), | |
4604 // simultaneously clearing it. | |
4605 dirtyRegion = | |
4606 _modUnionTable.getAndClearMarkedRegion(nextAddr, endAddr); | |
4607 assert(dirtyRegion.start() >= nextAddr, | |
4608 "returned region inconsistent?"); | |
4609 } | |
4610 // Remember where the next search should begin. | |
4611 // The returned region (if non-empty) is a right open interval, | |
4612 // so lastOffset is obtained from the right end of that | |
4613 // interval. | |
4614 lastAddr = dirtyRegion.end(); | |
4615 // Should do something more transparent and less hacky XXX | |
4616 numDirtyCards = | |
4617 _modUnionTable.heapWordDiffToOffsetDiff(dirtyRegion.word_size()); | |
4618 | |
4619 // We'll scan the cards in the dirty region (with periodic | |
4620 // yields for foreground GC as needed). | |
4621 if (!dirtyRegion.is_empty()) { | |
4622 assert(numDirtyCards > 0, "consistency check"); | |
4623 HeapWord* stop_point = NULL; | |
453
c96030fff130
6684579: SoftReference processing can be made more efficient
ysr
parents:
452
diff
changeset
|
4624 stopTimer(); |
935 | 4625 // Potential yield point |
453
c96030fff130
6684579: SoftReference processing can be made more efficient
ysr
parents:
452
diff
changeset
|
4626 CMSTokenSyncWithLocks ts(true, gen->freelistLock(), |
c96030fff130
6684579: SoftReference processing can be made more efficient
ysr
parents:
452
diff
changeset
|
4627 bitMapLock()); |
c96030fff130
6684579: SoftReference processing can be made more efficient
ysr
parents:
452
diff
changeset
|
4628 startTimer(); |
0 | 4629 { |
4630 verify_work_stacks_empty(); | |
4631 verify_overflow_empty(); | |
4632 sample_eden(); | |
1190
4788266644c1
6895236: CMS: cmsOopClosures.inline.hpp:43 assert(..., "Should remember klasses in this context")
jmasa
parents:
1145
diff
changeset
|
4633 DEBUG_ONLY(RememberKlassesChecker mx(should_unload_classes());) |
0 | 4634 stop_point = |
4635 gen->cmsSpace()->object_iterate_careful_m(dirtyRegion, cl); | |
4636 } | |
4637 if (stop_point != NULL) { | |
4638 // The careful iteration stopped early either because it found an | |
4639 // uninitialized object, or because we were in the midst of an | |
4640 // "abortable preclean", which should now be aborted. Redirty | |
4641 // the bits corresponding to the partially-scanned or unscanned | |
4642 // cards. We'll either restart at the next block boundary or | |
4643 // abort the preclean. | |
4644 assert((CMSPermGenPrecleaningEnabled && (gen == _permGen)) || | |
4645 (_collectorState == AbortablePreclean && should_abort_preclean()), | |
4646 "Unparsable objects should only be in perm gen."); | |
4647 _modUnionTable.mark_range(MemRegion(stop_point, dirtyRegion.end())); | |
4648 if (should_abort_preclean()) { | |
4649 break; // out of preclean loop | |
4650 } else { | |
4651 // Compute the next address at which preclean should pick up; | |
4652 // might need bitMapLock in order to read P-bits. | |
4653 lastAddr = next_card_start_after_block(stop_point); | |
4654 } | |
4655 } | |
4656 } else { | |
4657 assert(lastAddr == endAddr, "consistency check"); | |
4658 assert(numDirtyCards == 0, "consistency check"); | |
4659 break; | |
4660 } | |
4661 } | |
4662 verify_work_stacks_empty(); | |
4663 verify_overflow_empty(); | |
4664 return cumNumDirtyCards; | |
4665 } | |
4666 | |
4667 // NOTE: preclean_mod_union_table() above and preclean_card_table() | |
4668 // below are largely identical; if you need to modify | |
4669 // one of these methods, please check the other method too. | |
4670 | |
4671 size_t CMSCollector::preclean_card_table(ConcurrentMarkSweepGeneration* gen, | |
4672 ScanMarkedObjectsAgainCarefullyClosure* cl) { | |
4673 // strategy: it's similar to precleamModUnionTable above, in that | |
4674 // we accumulate contiguous ranges of dirty cards, mark these cards | |
4675 // precleaned, then scan the region covered by these cards. | |
4676 HeapWord* endAddr = (HeapWord*)(gen->_virtual_space.high()); | |
4677 HeapWord* startAddr = (HeapWord*)(gen->_virtual_space.low()); | |
4678 | |
4679 cl->setFreelistLock(gen->freelistLock()); // needed for yielding | |
4680 | |
4681 size_t numDirtyCards, cumNumDirtyCards; | |
4682 HeapWord *lastAddr, *nextAddr; | |
4683 | |
4684 for (cumNumDirtyCards = numDirtyCards = 0, | |
4685 nextAddr = lastAddr = startAddr; | |
4686 nextAddr < endAddr; | |
4687 nextAddr = lastAddr, cumNumDirtyCards += numDirtyCards) { | |
4688 | |
4689 ResourceMark rm; | |
4690 HandleMark hm; | |
4691 | |
4692 MemRegion dirtyRegion; | |
4693 { | |
4694 // See comments in "Precleaning notes" above on why we | |
4695 // do this locking. XXX Could the locking overheads be | |
4696 // too high when dirty cards are sparse? [I don't think so.] | |
4697 stopTimer(); | |
4698 CMSTokenSync x(true); // is cms thread | |
4699 startTimer(); | |
4700 sample_eden(); | |
4701 // Get and clear dirty region from card table | |
342
37f87013dfd8
6711316: Open source the Garbage-First garbage collector
ysr
parents:
143
diff
changeset
|
4702 dirtyRegion = _ct->ct_bs()->dirty_card_range_after_reset( |
37f87013dfd8
6711316: Open source the Garbage-First garbage collector
ysr
parents:
143
diff
changeset
|
4703 MemRegion(nextAddr, endAddr), |
37f87013dfd8
6711316: Open source the Garbage-First garbage collector
ysr
parents:
143
diff
changeset
|
4704 true, |
37f87013dfd8
6711316: Open source the Garbage-First garbage collector
ysr
parents:
143
diff
changeset
|
4705 CardTableModRefBS::precleaned_card_val()); |
37f87013dfd8
6711316: Open source the Garbage-First garbage collector
ysr
parents:
143
diff
changeset
|
4706 |
0 | 4707 assert(dirtyRegion.start() >= nextAddr, |
4708 "returned region inconsistent?"); | |
4709 } | |
4710 lastAddr = dirtyRegion.end(); | |
4711 numDirtyCards = | |
4712 dirtyRegion.word_size()/CardTableModRefBS::card_size_in_words; | |
4713 | |
4714 if (!dirtyRegion.is_empty()) { | |
4715 stopTimer(); | |
4716 CMSTokenSyncWithLocks ts(true, gen->freelistLock(), bitMapLock()); | |
4717 startTimer(); | |
4718 sample_eden(); | |
4719 verify_work_stacks_empty(); | |
4720 verify_overflow_empty(); | |
1190
4788266644c1
6895236: CMS: cmsOopClosures.inline.hpp:43 assert(..., "Should remember klasses in this context")
jmasa
parents:
1145
diff
changeset
|
4721 DEBUG_ONLY(RememberKlassesChecker mx(should_unload_classes());) |
0 | 4722 HeapWord* stop_point = |
4723 gen->cmsSpace()->object_iterate_careful_m(dirtyRegion, cl); | |
4724 if (stop_point != NULL) { | |
4725 // The careful iteration stopped early because it found an | |
4726 // uninitialized object. Redirty the bits corresponding to the | |
4727 // partially-scanned or unscanned cards, and start again at the | |
4728 // next block boundary. | |
4729 assert(CMSPermGenPrecleaningEnabled || | |
4730 (_collectorState == AbortablePreclean && should_abort_preclean()), | |
4731 "Unparsable objects should only be in perm gen."); | |
4732 _ct->ct_bs()->invalidate(MemRegion(stop_point, dirtyRegion.end())); | |
4733 if (should_abort_preclean()) { | |
4734 break; // out of preclean loop | |
4735 } else { | |
4736 // Compute the next address at which preclean should pick up. | |
4737 lastAddr = next_card_start_after_block(stop_point); | |
4738 } | |
4739 } | |
4740 } else { | |
4741 break; | |
4742 } | |
4743 } | |
4744 verify_work_stacks_empty(); | |
4745 verify_overflow_empty(); | |
4746 return cumNumDirtyCards; | |
4747 } | |
4748 | |
4749 void CMSCollector::checkpointRootsFinal(bool asynch, | |
4750 bool clear_all_soft_refs, bool init_mark_was_synchronous) { | |
4751 assert(_collectorState == FinalMarking, "incorrect state transition?"); | |
4752 check_correct_thread_executing(); | |
4753 // world is stopped at this checkpoint | |
4754 assert(SafepointSynchronize::is_at_safepoint(), | |
4755 "world should be stopped"); | |
4756 verify_work_stacks_empty(); | |
4757 verify_overflow_empty(); | |
4758 | |
4759 SpecializationStats::clear(); | |
4760 if (PrintGCDetails) { | |
4761 gclog_or_tty->print("[YG occupancy: "SIZE_FORMAT" K ("SIZE_FORMAT" K)]", | |
4762 _young_gen->used() / K, | |
4763 _young_gen->capacity() / K); | |
4764 } | |
4765 if (asynch) { | |
4766 if (CMSScavengeBeforeRemark) { | |
4767 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
4768 // Temporarily set flag to false, GCH->do_collection will | |
4769 // expect it to be false and set to true | |
4770 FlagSetting fl(gch->_is_gc_active, false); | |
4771 NOT_PRODUCT(TraceTime t("Scavenge-Before-Remark", | |
4772 PrintGCDetails && Verbose, true, gclog_or_tty);) | |
4773 int level = _cmsGen->level() - 1; | |
4774 if (level >= 0) { | |
4775 gch->do_collection(true, // full (i.e. force, see below) | |
4776 false, // !clear_all_soft_refs | |
4777 0, // size | |
4778 false, // is_tlab | |
4779 level // max_level | |
4780 ); | |
4781 } | |
4782 } | |
4783 FreelistLocker x(this); | |
4784 MutexLockerEx y(bitMapLock(), | |
4785 Mutex::_no_safepoint_check_flag); | |
4786 assert(!init_mark_was_synchronous, "but that's impossible!"); | |
4787 checkpointRootsFinalWork(asynch, clear_all_soft_refs, false); | |
4788 } else { | |
4789 // already have all the locks | |
4790 checkpointRootsFinalWork(asynch, clear_all_soft_refs, | |
4791 init_mark_was_synchronous); | |
4792 } | |
4793 verify_work_stacks_empty(); | |
4794 verify_overflow_empty(); | |
4795 SpecializationStats::print(); | |
4796 } | |
4797 | |
4798 void CMSCollector::checkpointRootsFinalWork(bool asynch, | |
4799 bool clear_all_soft_refs, bool init_mark_was_synchronous) { | |
4800 | |
4801 NOT_PRODUCT(TraceTime tr("checkpointRootsFinalWork", PrintGCDetails, false, gclog_or_tty);) | |
4802 | |
4803 assert(haveFreelistLocks(), "must have free list locks"); | |
4804 assert_lock_strong(bitMapLock()); | |
4805 | |
4806 if (UseAdaptiveSizePolicy) { | |
4807 size_policy()->checkpoint_roots_final_begin(); | |
4808 } | |
4809 | |
4810 ResourceMark rm; | |
4811 HandleMark hm; | |
4812 | |
4813 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
4814 | |
94
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
4815 if (should_unload_classes()) { |
0 | 4816 CodeCache::gc_prologue(); |
4817 } | |
4818 assert(haveFreelistLocks(), "must have free list locks"); | |
4819 assert_lock_strong(bitMapLock()); | |
4820 | |
1190
4788266644c1
6895236: CMS: cmsOopClosures.inline.hpp:43 assert(..., "Should remember klasses in this context")
jmasa
parents:
1145
diff
changeset
|
4821 DEBUG_ONLY(RememberKlassesChecker fmx(should_unload_classes());) |
0 | 4822 if (!init_mark_was_synchronous) { |
4823 // We might assume that we need not fill TLAB's when | |
4824 // CMSScavengeBeforeRemark is set, because we may have just done | |
4825 // a scavenge which would have filled all TLAB's -- and besides | |
4826 // Eden would be empty. This however may not always be the case -- | |
4827 // for instance although we asked for a scavenge, it may not have | |
4828 // happened because of a JNI critical section. We probably need | |
4829 // a policy for deciding whether we can in that case wait until | |
4830 // the critical section releases and then do the remark following | |
4831 // the scavenge, and skip it here. In the absence of that policy, | |
4832 // or of an indication of whether the scavenge did indeed occur, | |
4833 // we cannot rely on TLAB's having been filled and must do | |
4834 // so here just in case a scavenge did not happen. | |
4835 gch->ensure_parsability(false); // fill TLAB's, but no need to retire them | |
4836 // Update the saved marks which may affect the root scans. | |
4837 gch->save_marks(); | |
4838 | |
4839 { | |
4840 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact;) | |
4841 | |
4842 // Note on the role of the mod union table: | |
4843 // Since the marker in "markFromRoots" marks concurrently with | |
4844 // mutators, it is possible for some reachable objects not to have been | |
4845 // scanned. For instance, an only reference to an object A was | |
4846 // placed in object B after the marker scanned B. Unless B is rescanned, | |
4847 // A would be collected. Such updates to references in marked objects | |
4848 // are detected via the mod union table which is the set of all cards | |
4849 // dirtied since the first checkpoint in this GC cycle and prior to | |
4850 // the most recent young generation GC, minus those cleaned up by the | |
4851 // concurrent precleaning. | |
4852 if (CMSParallelRemarkEnabled && ParallelGCThreads > 0) { | |
4853 TraceTime t("Rescan (parallel) ", PrintGCDetails, false, gclog_or_tty); | |
4854 do_remark_parallel(); | |
4855 } else { | |
4856 TraceTime t("Rescan (non-parallel) ", PrintGCDetails, false, | |
4857 gclog_or_tty); | |
4858 do_remark_non_parallel(); | |
4859 } | |
4860 } | |
4861 } else { | |
4862 assert(!asynch, "Can't have init_mark_was_synchronous in asynch mode"); | |
4863 // The initial mark was stop-world, so there's no rescanning to | |
4864 // do; go straight on to the next step below. | |
4865 } | |
4866 verify_work_stacks_empty(); | |
4867 verify_overflow_empty(); | |
4868 | |
4869 { | |
4870 NOT_PRODUCT(TraceTime ts("refProcessingWork", PrintGCDetails, false, gclog_or_tty);) | |
4871 refProcessingWork(asynch, clear_all_soft_refs); | |
4872 } | |
4873 verify_work_stacks_empty(); | |
4874 verify_overflow_empty(); | |
4875 | |
94
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
4876 if (should_unload_classes()) { |
0 | 4877 CodeCache::gc_epilogue(); |
4878 } | |
4879 | |
4880 // If we encountered any (marking stack / work queue) overflow | |
4881 // events during the current CMS cycle, take appropriate | |
4882 // remedial measures, where possible, so as to try and avoid | |
4883 // recurrence of that condition. | |
4884 assert(_markStack.isEmpty(), "No grey objects"); | |
4885 size_t ser_ovflw = _ser_pmc_remark_ovflw + _ser_pmc_preclean_ovflw + | |
452
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
4886 _ser_kac_ovflw + _ser_kac_preclean_ovflw; |
0 | 4887 if (ser_ovflw > 0) { |
4888 if (PrintCMSStatistics != 0) { | |
4889 gclog_or_tty->print_cr("Marking stack overflow (benign) " | |
452
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
4890 "(pmc_pc="SIZE_FORMAT", pmc_rm="SIZE_FORMAT", kac="SIZE_FORMAT |
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
4891 ", kac_preclean="SIZE_FORMAT")", |
0 | 4892 _ser_pmc_preclean_ovflw, _ser_pmc_remark_ovflw, |
452
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
4893 _ser_kac_ovflw, _ser_kac_preclean_ovflw); |
0 | 4894 } |
4895 _markStack.expand(); | |
4896 _ser_pmc_remark_ovflw = 0; | |
4897 _ser_pmc_preclean_ovflw = 0; | |
452
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
4898 _ser_kac_preclean_ovflw = 0; |
0 | 4899 _ser_kac_ovflw = 0; |
4900 } | |
4901 if (_par_pmc_remark_ovflw > 0 || _par_kac_ovflw > 0) { | |
4902 if (PrintCMSStatistics != 0) { | |
4903 gclog_or_tty->print_cr("Work queue overflow (benign) " | |
4904 "(pmc_rm="SIZE_FORMAT", kac="SIZE_FORMAT")", | |
4905 _par_pmc_remark_ovflw, _par_kac_ovflw); | |
4906 } | |
4907 _par_pmc_remark_ovflw = 0; | |
4908 _par_kac_ovflw = 0; | |
4909 } | |
4910 if (PrintCMSStatistics != 0) { | |
4911 if (_markStack._hit_limit > 0) { | |
4912 gclog_or_tty->print_cr(" (benign) Hit max stack size limit ("SIZE_FORMAT")", | |
4913 _markStack._hit_limit); | |
4914 } | |
4915 if (_markStack._failed_double > 0) { | |
4916 gclog_or_tty->print_cr(" (benign) Failed stack doubling ("SIZE_FORMAT")," | |
4917 " current capacity "SIZE_FORMAT, | |
4918 _markStack._failed_double, | |
4919 _markStack.capacity()); | |
4920 } | |
4921 } | |
4922 _markStack._hit_limit = 0; | |
4923 _markStack._failed_double = 0; | |
4924 | |
935 | 4925 // Check that all the klasses have been checked |
4926 assert(_revisitStack.isEmpty(), "Not all klasses revisited"); | |
4927 | |
0 | 4928 if ((VerifyAfterGC || VerifyDuringGC) && |
4929 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
4930 verify_after_remark(); | |
4931 } | |
4932 | |
4933 // Change under the freelistLocks. | |
4934 _collectorState = Sweeping; | |
4935 // Call isAllClear() under bitMapLock | |
4936 assert(_modUnionTable.isAllClear(), "Should be clear by end of the" | |
4937 " final marking"); | |
4938 if (UseAdaptiveSizePolicy) { | |
4939 size_policy()->checkpoint_roots_final_end(gch->gc_cause()); | |
4940 } | |
4941 } | |
4942 | |
4943 // Parallel remark task | |
4944 class CMSParRemarkTask: public AbstractGangTask { | |
4945 CMSCollector* _collector; | |
4946 WorkGang* _workers; | |
4947 int _n_workers; | |
4948 CompactibleFreeListSpace* _cms_space; | |
4949 CompactibleFreeListSpace* _perm_space; | |
4950 | |
4951 // The per-thread work queues, available here for stealing. | |
4952 OopTaskQueueSet* _task_queues; | |
4953 ParallelTaskTerminator _term; | |
4954 | |
4955 public: | |
4956 CMSParRemarkTask(CMSCollector* collector, | |
4957 CompactibleFreeListSpace* cms_space, | |
4958 CompactibleFreeListSpace* perm_space, | |
4959 int n_workers, WorkGang* workers, | |
4960 OopTaskQueueSet* task_queues): | |
4961 AbstractGangTask("Rescan roots and grey objects in parallel"), | |
4962 _collector(collector), | |
4963 _cms_space(cms_space), _perm_space(perm_space), | |
4964 _n_workers(n_workers), | |
4965 _workers(workers), | |
4966 _task_queues(task_queues), | |
4967 _term(workers->total_workers(), task_queues) { } | |
4968 | |
4969 OopTaskQueueSet* task_queues() { return _task_queues; } | |
4970 | |
4971 OopTaskQueue* work_queue(int i) { return task_queues()->queue(i); } | |
4972 | |
4973 ParallelTaskTerminator* terminator() { return &_term; } | |
4974 | |
4975 void work(int i); | |
4976 | |
4977 private: | |
4978 // Work method in support of parallel rescan ... of young gen spaces | |
4979 void do_young_space_rescan(int i, Par_MarkRefsIntoAndScanClosure* cl, | |
4980 ContiguousSpace* space, | |
4981 HeapWord** chunk_array, size_t chunk_top); | |
4982 | |
4983 // ... of dirty cards in old space | |
4984 void do_dirty_card_rescan_tasks(CompactibleFreeListSpace* sp, int i, | |
4985 Par_MarkRefsIntoAndScanClosure* cl); | |
4986 | |
4987 // ... work stealing for the above | |
4988 void do_work_steal(int i, Par_MarkRefsIntoAndScanClosure* cl, int* seed); | |
4989 }; | |
4990 | |
4991 void CMSParRemarkTask::work(int i) { | |
4992 elapsedTimer _timer; | |
4993 ResourceMark rm; | |
4994 HandleMark hm; | |
4995 | |
4996 // ---------- rescan from roots -------------- | |
4997 _timer.start(); | |
4998 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
4999 Par_MarkRefsIntoAndScanClosure par_mrias_cl(_collector, | |
5000 _collector->_span, _collector->ref_processor(), | |
5001 &(_collector->_markBitMap), | |
5002 work_queue(i), &(_collector->_revisitStack)); | |
5003 | |
5004 // Rescan young gen roots first since these are likely | |
5005 // coarsely partitioned and may, on that account, constitute | |
5006 // the critical path; thus, it's best to start off that | |
5007 // work first. | |
5008 // ---------- young gen roots -------------- | |
5009 { | |
5010 DefNewGeneration* dng = _collector->_young_gen->as_DefNewGeneration(); | |
5011 EdenSpace* eden_space = dng->eden(); | |
5012 ContiguousSpace* from_space = dng->from(); | |
5013 ContiguousSpace* to_space = dng->to(); | |
5014 | |
5015 HeapWord** eca = _collector->_eden_chunk_array; | |
5016 size_t ect = _collector->_eden_chunk_index; | |
5017 HeapWord** sca = _collector->_survivor_chunk_array; | |
5018 size_t sct = _collector->_survivor_chunk_index; | |
5019 | |
5020 assert(ect <= _collector->_eden_chunk_capacity, "out of bounds"); | |
5021 assert(sct <= _collector->_survivor_chunk_capacity, "out of bounds"); | |
5022 | |
5023 do_young_space_rescan(i, &par_mrias_cl, to_space, NULL, 0); | |
5024 do_young_space_rescan(i, &par_mrias_cl, from_space, sca, sct); | |
5025 do_young_space_rescan(i, &par_mrias_cl, eden_space, eca, ect); | |
5026 | |
5027 _timer.stop(); | |
5028 if (PrintCMSStatistics != 0) { | |
5029 gclog_or_tty->print_cr( | |
5030 "Finished young gen rescan work in %dth thread: %3.3f sec", | |
5031 i, _timer.seconds()); | |
5032 } | |
5033 } | |
5034 | |
5035 // ---------- remaining roots -------------- | |
5036 _timer.reset(); | |
5037 _timer.start(); | |
5038 gch->gen_process_strong_roots(_collector->_cmsGen->level(), | |
5039 false, // yg was scanned above | |
989
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
5040 false, // this is parallel code |
0 | 5041 true, // collecting perm gen |
5042 SharedHeap::ScanningOption(_collector->CMSCollector::roots_scanning_options()), | |
989
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
5043 &par_mrias_cl, |
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
5044 true, // walk all of code cache if (so & SO_CodeCache) |
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
5045 NULL); |
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
5046 assert(_collector->should_unload_classes() |
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
5047 || (_collector->CMSCollector::roots_scanning_options() & SharedHeap::SO_CodeCache), |
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
5048 "if we didn't scan the code cache, we have to be ready to drop nmethods with expired weak oops"); |
0 | 5049 _timer.stop(); |
5050 if (PrintCMSStatistics != 0) { | |
5051 gclog_or_tty->print_cr( | |
5052 "Finished remaining root rescan work in %dth thread: %3.3f sec", | |
5053 i, _timer.seconds()); | |
5054 } | |
5055 | |
5056 // ---------- rescan dirty cards ------------ | |
5057 _timer.reset(); | |
5058 _timer.start(); | |
5059 | |
5060 // Do the rescan tasks for each of the two spaces | |
5061 // (cms_space and perm_space) in turn. | |
5062 do_dirty_card_rescan_tasks(_cms_space, i, &par_mrias_cl); | |
5063 do_dirty_card_rescan_tasks(_perm_space, i, &par_mrias_cl); | |
5064 _timer.stop(); | |
5065 if (PrintCMSStatistics != 0) { | |
5066 gclog_or_tty->print_cr( | |
5067 "Finished dirty card rescan work in %dth thread: %3.3f sec", | |
5068 i, _timer.seconds()); | |
5069 } | |
5070 | |
5071 // ---------- steal work from other threads ... | |
5072 // ---------- ... and drain overflow list. | |
5073 _timer.reset(); | |
5074 _timer.start(); | |
5075 do_work_steal(i, &par_mrias_cl, _collector->hash_seed(i)); | |
5076 _timer.stop(); | |
5077 if (PrintCMSStatistics != 0) { | |
5078 gclog_or_tty->print_cr( | |
5079 "Finished work stealing in %dth thread: %3.3f sec", | |
5080 i, _timer.seconds()); | |
5081 } | |
5082 } | |
5083 | |
5084 void | |
5085 CMSParRemarkTask::do_young_space_rescan(int i, | |
5086 Par_MarkRefsIntoAndScanClosure* cl, ContiguousSpace* space, | |
5087 HeapWord** chunk_array, size_t chunk_top) { | |
5088 // Until all tasks completed: | |
5089 // . claim an unclaimed task | |
5090 // . compute region boundaries corresponding to task claimed | |
5091 // using chunk_array | |
5092 // . par_oop_iterate(cl) over that region | |
5093 | |
5094 ResourceMark rm; | |
5095 HandleMark hm; | |
5096 | |
5097 SequentialSubTasksDone* pst = space->par_seq_tasks(); | |
5098 assert(pst->valid(), "Uninitialized use?"); | |
5099 | |
5100 int nth_task = 0; | |
5101 int n_tasks = pst->n_tasks(); | |
5102 | |
5103 HeapWord *start, *end; | |
5104 while (!pst->is_task_claimed(/* reference */ nth_task)) { | |
5105 // We claimed task # nth_task; compute its boundaries. | |
5106 if (chunk_top == 0) { // no samples were taken | |
5107 assert(nth_task == 0 && n_tasks == 1, "Can have only 1 EdenSpace task"); | |
5108 start = space->bottom(); | |
5109 end = space->top(); | |
5110 } else if (nth_task == 0) { | |
5111 start = space->bottom(); | |
5112 end = chunk_array[nth_task]; | |
5113 } else if (nth_task < (jint)chunk_top) { | |
5114 assert(nth_task >= 1, "Control point invariant"); | |
5115 start = chunk_array[nth_task - 1]; | |
5116 end = chunk_array[nth_task]; | |
5117 } else { | |
5118 assert(nth_task == (jint)chunk_top, "Control point invariant"); | |
5119 start = chunk_array[chunk_top - 1]; | |
5120 end = space->top(); | |
5121 } | |
5122 MemRegion mr(start, end); | |
5123 // Verify that mr is in space | |
5124 assert(mr.is_empty() || space->used_region().contains(mr), | |
5125 "Should be in space"); | |
5126 // Verify that "start" is an object boundary | |
5127 assert(mr.is_empty() || oop(mr.start())->is_oop(), | |
5128 "Should be an oop"); | |
5129 space->par_oop_iterate(mr, cl); | |
5130 } | |
5131 pst->all_tasks_completed(); | |
5132 } | |
5133 | |
5134 void | |
5135 CMSParRemarkTask::do_dirty_card_rescan_tasks( | |
5136 CompactibleFreeListSpace* sp, int i, | |
5137 Par_MarkRefsIntoAndScanClosure* cl) { | |
5138 // Until all tasks completed: | |
5139 // . claim an unclaimed task | |
5140 // . compute region boundaries corresponding to task claimed | |
5141 // . transfer dirty bits ct->mut for that region | |
5142 // . apply rescanclosure to dirty mut bits for that region | |
5143 | |
5144 ResourceMark rm; | |
5145 HandleMark hm; | |
5146 | |
5147 OopTaskQueue* work_q = work_queue(i); | |
5148 ModUnionClosure modUnionClosure(&(_collector->_modUnionTable)); | |
5149 // CAUTION! CAUTION! CAUTION! CAUTION! CAUTION! CAUTION! CAUTION! | |
5150 // CAUTION: This closure has state that persists across calls to | |
5151 // the work method dirty_range_iterate_clear() in that it has | |
5152 // imbedded in it a (subtype of) UpwardsObjectClosure. The | |
5153 // use of that state in the imbedded UpwardsObjectClosure instance | |
5154 // assumes that the cards are always iterated (even if in parallel | |
5155 // by several threads) in monotonically increasing order per each | |
5156 // thread. This is true of the implementation below which picks | |
5157 // card ranges (chunks) in monotonically increasing order globally | |
5158 // and, a-fortiori, in monotonically increasing order per thread | |
5159 // (the latter order being a subsequence of the former). | |
5160 // If the work code below is ever reorganized into a more chaotic | |
5161 // work-partitioning form than the current "sequential tasks" | |
5162 // paradigm, the use of that persistent state will have to be | |
5163 // revisited and modified appropriately. See also related | |
5164 // bug 4756801 work on which should examine this code to make | |
5165 // sure that the changes there do not run counter to the | |
5166 // assumptions made here and necessary for correctness and | |
5167 // efficiency. Note also that this code might yield inefficient | |
5168 // behaviour in the case of very large objects that span one or | |
5169 // more work chunks. Such objects would potentially be scanned | |
5170 // several times redundantly. Work on 4756801 should try and | |
5171 // address that performance anomaly if at all possible. XXX | |
5172 MemRegion full_span = _collector->_span; | |
5173 CMSBitMap* bm = &(_collector->_markBitMap); // shared | |
5174 CMSMarkStack* rs = &(_collector->_revisitStack); // shared | |
5175 MarkFromDirtyCardsClosure | |
5176 greyRescanClosure(_collector, full_span, // entire span of interest | |
5177 sp, bm, work_q, rs, cl); | |
5178 | |
5179 SequentialSubTasksDone* pst = sp->conc_par_seq_tasks(); | |
5180 assert(pst->valid(), "Uninitialized use?"); | |
5181 int nth_task = 0; | |
5182 const int alignment = CardTableModRefBS::card_size * BitsPerWord; | |
5183 MemRegion span = sp->used_region(); | |
5184 HeapWord* start_addr = span.start(); | |
5185 HeapWord* end_addr = (HeapWord*)round_to((intptr_t)span.end(), | |
5186 alignment); | |
5187 const size_t chunk_size = sp->rescan_task_size(); // in HeapWord units | |
5188 assert((HeapWord*)round_to((intptr_t)start_addr, alignment) == | |
5189 start_addr, "Check alignment"); | |
5190 assert((size_t)round_to((intptr_t)chunk_size, alignment) == | |
5191 chunk_size, "Check alignment"); | |
5192 | |
5193 while (!pst->is_task_claimed(/* reference */ nth_task)) { | |
5194 // Having claimed the nth_task, compute corresponding mem-region, | |
5195 // which is a-fortiori aligned correctly (i.e. at a MUT bopundary). | |
5196 // The alignment restriction ensures that we do not need any | |
5197 // synchronization with other gang-workers while setting or | |
5198 // clearing bits in thus chunk of the MUT. | |
5199 MemRegion this_span = MemRegion(start_addr + nth_task*chunk_size, | |
5200 start_addr + (nth_task+1)*chunk_size); | |
5201 // The last chunk's end might be way beyond end of the | |
5202 // used region. In that case pull back appropriately. | |
5203 if (this_span.end() > end_addr) { | |
5204 this_span.set_end(end_addr); | |
5205 assert(!this_span.is_empty(), "Program logic (calculation of n_tasks)"); | |
5206 } | |
5207 // Iterate over the dirty cards covering this chunk, marking them | |
5208 // precleaned, and setting the corresponding bits in the mod union | |
5209 // table. Since we have been careful to partition at Card and MUT-word | |
5210 // boundaries no synchronization is needed between parallel threads. | |
5211 _collector->_ct->ct_bs()->dirty_card_iterate(this_span, | |
5212 &modUnionClosure); | |
5213 | |
5214 // Having transferred these marks into the modUnionTable, | |
5215 // rescan the marked objects on the dirty cards in the modUnionTable. | |
5216 // Even if this is at a synchronous collection, the initial marking | |
5217 // may have been done during an asynchronous collection so there | |
5218 // may be dirty bits in the mod-union table. | |
5219 _collector->_modUnionTable.dirty_range_iterate_clear( | |
5220 this_span, &greyRescanClosure); | |
5221 _collector->_modUnionTable.verifyNoOneBitsInRange( | |
5222 this_span.start(), | |
5223 this_span.end()); | |
5224 } | |
5225 pst->all_tasks_completed(); // declare that i am done | |
5226 } | |
5227 | |
5228 // . see if we can share work_queues with ParNew? XXX | |
5229 void | |
5230 CMSParRemarkTask::do_work_steal(int i, Par_MarkRefsIntoAndScanClosure* cl, | |
5231 int* seed) { | |
5232 OopTaskQueue* work_q = work_queue(i); | |
5233 NOT_PRODUCT(int num_steals = 0;) | |
5234 oop obj_to_scan; | |
5235 CMSBitMap* bm = &(_collector->_markBitMap); | |
5236 | |
5237 while (true) { | |
5238 // Completely finish any left over work from (an) earlier round(s) | |
5239 cl->trim_queue(0); | |
679
cea947c8a988
6819891: ParNew: Fix work queue overflow code to deal correctly with +UseCompressedOops
ysr
parents:
628
diff
changeset
|
5240 size_t num_from_overflow_list = MIN2((size_t)(work_q->max_elems() - work_q->size())/4, |
cea947c8a988
6819891: ParNew: Fix work queue overflow code to deal correctly with +UseCompressedOops
ysr
parents:
628
diff
changeset
|
5241 (size_t)ParGCDesiredObjsFromOverflowList); |
0 | 5242 // Now check if there's any work in the overflow list |
5243 if (_collector->par_take_from_overflow_list(num_from_overflow_list, | |
5244 work_q)) { | |
5245 // found something in global overflow list; | |
5246 // not yet ready to go stealing work from others. | |
5247 // We'd like to assert(work_q->size() != 0, ...) | |
5248 // because we just took work from the overflow list, | |
5249 // but of course we can't since all of that could have | |
5250 // been already stolen from us. | |
5251 // "He giveth and He taketh away." | |
5252 continue; | |
5253 } | |
5254 // Verify that we have no work before we resort to stealing | |
5255 assert(work_q->size() == 0, "Have work, shouldn't steal"); | |
5256 // Try to steal from other queues that have work | |
5257 if (task_queues()->steal(i, seed, /* reference */ obj_to_scan)) { | |
5258 NOT_PRODUCT(num_steals++;) | |
5259 assert(obj_to_scan->is_oop(), "Oops, not an oop!"); | |
5260 assert(bm->isMarked((HeapWord*)obj_to_scan), "Stole an unmarked oop?"); | |
5261 // Do scanning work | |
5262 obj_to_scan->oop_iterate(cl); | |
5263 // Loop around, finish this work, and try to steal some more | |
5264 } else if (terminator()->offer_termination()) { | |
5265 break; // nirvana from the infinite cycle | |
5266 } | |
5267 } | |
5268 NOT_PRODUCT( | |
5269 if (PrintCMSStatistics != 0) { | |
5270 gclog_or_tty->print("\n\t(%d: stole %d oops)", i, num_steals); | |
5271 } | |
5272 ) | |
5273 assert(work_q->size() == 0 && _collector->overflow_list_is_empty(), | |
5274 "Else our work is not yet done"); | |
5275 } | |
5276 | |
5277 // Return a thread-local PLAB recording array, as appropriate. | |
5278 void* CMSCollector::get_data_recorder(int thr_num) { | |
5279 if (_survivor_plab_array != NULL && | |
5280 (CMSPLABRecordAlways || | |
5281 (_collectorState > Marking && _collectorState < FinalMarking))) { | |
5282 assert(thr_num < (int)ParallelGCThreads, "thr_num is out of bounds"); | |
5283 ChunkArray* ca = &_survivor_plab_array[thr_num]; | |
5284 ca->reset(); // clear it so that fresh data is recorded | |
5285 return (void*) ca; | |
5286 } else { | |
5287 return NULL; | |
5288 } | |
5289 } | |
5290 | |
5291 // Reset all the thread-local PLAB recording arrays | |
5292 void CMSCollector::reset_survivor_plab_arrays() { | |
5293 for (uint i = 0; i < ParallelGCThreads; i++) { | |
5294 _survivor_plab_array[i].reset(); | |
5295 } | |
5296 } | |
5297 | |
5298 // Merge the per-thread plab arrays into the global survivor chunk | |
5299 // array which will provide the partitioning of the survivor space | |
5300 // for CMS rescan. | |
5301 void CMSCollector::merge_survivor_plab_arrays(ContiguousSpace* surv) { | |
5302 assert(_survivor_plab_array != NULL, "Error"); | |
5303 assert(_survivor_chunk_array != NULL, "Error"); | |
5304 assert(_collectorState == FinalMarking, "Error"); | |
5305 for (uint j = 0; j < ParallelGCThreads; j++) { | |
5306 _cursor[j] = 0; | |
5307 } | |
5308 HeapWord* top = surv->top(); | |
5309 size_t i; | |
5310 for (i = 0; i < _survivor_chunk_capacity; i++) { // all sca entries | |
5311 HeapWord* min_val = top; // Higher than any PLAB address | |
5312 uint min_tid = 0; // position of min_val this round | |
5313 for (uint j = 0; j < ParallelGCThreads; j++) { | |
5314 ChunkArray* cur_sca = &_survivor_plab_array[j]; | |
5315 if (_cursor[j] == cur_sca->end()) { | |
5316 continue; | |
5317 } | |
5318 assert(_cursor[j] < cur_sca->end(), "ctl pt invariant"); | |
5319 HeapWord* cur_val = cur_sca->nth(_cursor[j]); | |
5320 assert(surv->used_region().contains(cur_val), "Out of bounds value"); | |
5321 if (cur_val < min_val) { | |
5322 min_tid = j; | |
5323 min_val = cur_val; | |
5324 } else { | |
5325 assert(cur_val < top, "All recorded addresses should be less"); | |
5326 } | |
5327 } | |
5328 // At this point min_val and min_tid are respectively | |
5329 // the least address in _survivor_plab_array[j]->nth(_cursor[j]) | |
5330 // and the thread (j) that witnesses that address. | |
5331 // We record this address in the _survivor_chunk_array[i] | |
5332 // and increment _cursor[min_tid] prior to the next round i. | |
5333 if (min_val == top) { | |
5334 break; | |
5335 } | |
5336 _survivor_chunk_array[i] = min_val; | |
5337 _cursor[min_tid]++; | |
5338 } | |
5339 // We are all done; record the size of the _survivor_chunk_array | |
5340 _survivor_chunk_index = i; // exclusive: [0, i) | |
5341 if (PrintCMSStatistics > 0) { | |
5342 gclog_or_tty->print(" (Survivor:" SIZE_FORMAT "chunks) ", i); | |
5343 } | |
5344 // Verify that we used up all the recorded entries | |
5345 #ifdef ASSERT | |
5346 size_t total = 0; | |
5347 for (uint j = 0; j < ParallelGCThreads; j++) { | |
5348 assert(_cursor[j] == _survivor_plab_array[j].end(), "Ctl pt invariant"); | |
5349 total += _cursor[j]; | |
5350 } | |
5351 assert(total == _survivor_chunk_index, "Ctl Pt Invariant"); | |
5352 // Check that the merged array is in sorted order | |
5353 if (total > 0) { | |
5354 for (size_t i = 0; i < total - 1; i++) { | |
5355 if (PrintCMSStatistics > 0) { | |
5356 gclog_or_tty->print(" (chunk" SIZE_FORMAT ":" INTPTR_FORMAT ") ", | |
5357 i, _survivor_chunk_array[i]); | |
5358 } | |
5359 assert(_survivor_chunk_array[i] < _survivor_chunk_array[i+1], | |
5360 "Not sorted"); | |
5361 } | |
5362 } | |
5363 #endif // ASSERT | |
5364 } | |
5365 | |
5366 // Set up the space's par_seq_tasks structure for work claiming | |
5367 // for parallel rescan of young gen. | |
5368 // See ParRescanTask where this is currently used. | |
5369 void | |
5370 CMSCollector:: | |
5371 initialize_sequential_subtasks_for_young_gen_rescan(int n_threads) { | |
5372 assert(n_threads > 0, "Unexpected n_threads argument"); | |
5373 DefNewGeneration* dng = (DefNewGeneration*)_young_gen; | |
5374 | |
5375 // Eden space | |
5376 { | |
5377 SequentialSubTasksDone* pst = dng->eden()->par_seq_tasks(); | |
5378 assert(!pst->valid(), "Clobbering existing data?"); | |
5379 // Each valid entry in [0, _eden_chunk_index) represents a task. | |
5380 size_t n_tasks = _eden_chunk_index + 1; | |
5381 assert(n_tasks == 1 || _eden_chunk_array != NULL, "Error"); | |
5382 pst->set_par_threads(n_threads); | |
5383 pst->set_n_tasks((int)n_tasks); | |
5384 } | |
5385 | |
5386 // Merge the survivor plab arrays into _survivor_chunk_array | |
5387 if (_survivor_plab_array != NULL) { | |
5388 merge_survivor_plab_arrays(dng->from()); | |
5389 } else { | |
5390 assert(_survivor_chunk_index == 0, "Error"); | |
5391 } | |
5392 | |
5393 // To space | |
5394 { | |
5395 SequentialSubTasksDone* pst = dng->to()->par_seq_tasks(); | |
5396 assert(!pst->valid(), "Clobbering existing data?"); | |
5397 pst->set_par_threads(n_threads); | |
5398 pst->set_n_tasks(1); | |
5399 assert(pst->valid(), "Error"); | |
5400 } | |
5401 | |
5402 // From space | |
5403 { | |
5404 SequentialSubTasksDone* pst = dng->from()->par_seq_tasks(); | |
5405 assert(!pst->valid(), "Clobbering existing data?"); | |
5406 size_t n_tasks = _survivor_chunk_index + 1; | |
5407 assert(n_tasks == 1 || _survivor_chunk_array != NULL, "Error"); | |
5408 pst->set_par_threads(n_threads); | |
5409 pst->set_n_tasks((int)n_tasks); | |
5410 assert(pst->valid(), "Error"); | |
5411 } | |
5412 } | |
5413 | |
5414 // Parallel version of remark | |
5415 void CMSCollector::do_remark_parallel() { | |
5416 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
5417 WorkGang* workers = gch->workers(); | |
5418 assert(workers != NULL, "Need parallel worker threads."); | |
5419 int n_workers = workers->total_workers(); | |
5420 CompactibleFreeListSpace* cms_space = _cmsGen->cmsSpace(); | |
5421 CompactibleFreeListSpace* perm_space = _permGen->cmsSpace(); | |
5422 | |
5423 CMSParRemarkTask tsk(this, | |
5424 cms_space, perm_space, | |
5425 n_workers, workers, task_queues()); | |
5426 | |
5427 // Set up for parallel process_strong_roots work. | |
5428 gch->set_par_threads(n_workers); | |
5429 // We won't be iterating over the cards in the card table updating | |
5430 // the younger_gen cards, so we shouldn't call the following else | |
5431 // the verification code as well as subsequent younger_refs_iterate | |
5432 // code would get confused. XXX | |
5433 // gch->rem_set()->prepare_for_younger_refs_iterate(true); // parallel | |
5434 | |
5435 // The young gen rescan work will not be done as part of | |
5436 // process_strong_roots (which currently doesn't knw how to | |
5437 // parallelize such a scan), but rather will be broken up into | |
5438 // a set of parallel tasks (via the sampling that the [abortable] | |
5439 // preclean phase did of EdenSpace, plus the [two] tasks of | |
5440 // scanning the [two] survivor spaces. Further fine-grain | |
5441 // parallelization of the scanning of the survivor spaces | |
5442 // themselves, and of precleaning of the younger gen itself | |
5443 // is deferred to the future. | |
5444 initialize_sequential_subtasks_for_young_gen_rescan(n_workers); | |
5445 | |
5446 // The dirty card rescan work is broken up into a "sequence" | |
5447 // of parallel tasks (per constituent space) that are dynamically | |
5448 // claimed by the parallel threads. | |
5449 cms_space->initialize_sequential_subtasks_for_rescan(n_workers); | |
5450 perm_space->initialize_sequential_subtasks_for_rescan(n_workers); | |
5451 | |
5452 // It turns out that even when we're using 1 thread, doing the work in a | |
5453 // separate thread causes wide variance in run times. We can't help this | |
5454 // in the multi-threaded case, but we special-case n=1 here to get | |
5455 // repeatable measurements of the 1-thread overhead of the parallel code. | |
5456 if (n_workers > 1) { | |
5457 // Make refs discovery MT-safe | |
5458 ReferenceProcessorMTMutator mt(ref_processor(), true); | |
989
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
5459 GenCollectedHeap::StrongRootsScope srs(gch); |
0 | 5460 workers->run_task(&tsk); |
5461 } else { | |
989
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
5462 GenCollectedHeap::StrongRootsScope srs(gch); |
0 | 5463 tsk.work(0); |
5464 } | |
5465 gch->set_par_threads(0); // 0 ==> non-parallel. | |
5466 // restore, single-threaded for now, any preserved marks | |
5467 // as a result of work_q overflow | |
5468 restore_preserved_marks_if_any(); | |
5469 } | |
5470 | |
5471 // Non-parallel version of remark | |
5472 void CMSCollector::do_remark_non_parallel() { | |
5473 ResourceMark rm; | |
5474 HandleMark hm; | |
5475 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
5476 MarkRefsIntoAndScanClosure | |
5477 mrias_cl(_span, ref_processor(), &_markBitMap, &_modUnionTable, | |
5478 &_markStack, &_revisitStack, this, | |
5479 false /* should_yield */, false /* not precleaning */); | |
5480 MarkFromDirtyCardsClosure | |
5481 markFromDirtyCardsClosure(this, _span, | |
5482 NULL, // space is set further below | |
5483 &_markBitMap, &_markStack, &_revisitStack, | |
5484 &mrias_cl); | |
5485 { | |
5486 TraceTime t("grey object rescan", PrintGCDetails, false, gclog_or_tty); | |
342
37f87013dfd8
6711316: Open source the Garbage-First garbage collector
ysr
parents:
143
diff
changeset
|
5487 // Iterate over the dirty cards, setting the corresponding bits in the |
37f87013dfd8
6711316: Open source the Garbage-First garbage collector
ysr
parents:
143
diff
changeset
|
5488 // mod union table. |
0 | 5489 { |
5490 ModUnionClosure modUnionClosure(&_modUnionTable); | |
5491 _ct->ct_bs()->dirty_card_iterate( | |
5492 _cmsGen->used_region(), | |
5493 &modUnionClosure); | |
5494 _ct->ct_bs()->dirty_card_iterate( | |
5495 _permGen->used_region(), | |
5496 &modUnionClosure); | |
5497 } | |
5498 // Having transferred these marks into the modUnionTable, we just need | |
5499 // to rescan the marked objects on the dirty cards in the modUnionTable. | |
5500 // The initial marking may have been done during an asynchronous | |
5501 // collection so there may be dirty bits in the mod-union table. | |
5502 const int alignment = | |
5503 CardTableModRefBS::card_size * BitsPerWord; | |
5504 { | |
5505 // ... First handle dirty cards in CMS gen | |
5506 markFromDirtyCardsClosure.set_space(_cmsGen->cmsSpace()); | |
5507 MemRegion ur = _cmsGen->used_region(); | |
5508 HeapWord* lb = ur.start(); | |
5509 HeapWord* ub = (HeapWord*)round_to((intptr_t)ur.end(), alignment); | |
5510 MemRegion cms_span(lb, ub); | |
5511 _modUnionTable.dirty_range_iterate_clear(cms_span, | |
5512 &markFromDirtyCardsClosure); | |
5513 verify_work_stacks_empty(); | |
5514 if (PrintCMSStatistics != 0) { | |
5515 gclog_or_tty->print(" (re-scanned "SIZE_FORMAT" dirty cards in cms gen) ", | |
5516 markFromDirtyCardsClosure.num_dirty_cards()); | |
5517 } | |
5518 } | |
5519 { | |
5520 // .. and then repeat for dirty cards in perm gen | |
5521 markFromDirtyCardsClosure.set_space(_permGen->cmsSpace()); | |
5522 MemRegion ur = _permGen->used_region(); | |
5523 HeapWord* lb = ur.start(); | |
5524 HeapWord* ub = (HeapWord*)round_to((intptr_t)ur.end(), alignment); | |
5525 MemRegion perm_span(lb, ub); | |
5526 _modUnionTable.dirty_range_iterate_clear(perm_span, | |
5527 &markFromDirtyCardsClosure); | |
5528 verify_work_stacks_empty(); | |
5529 if (PrintCMSStatistics != 0) { | |
5530 gclog_or_tty->print(" (re-scanned "SIZE_FORMAT" dirty cards in perm gen) ", | |
5531 markFromDirtyCardsClosure.num_dirty_cards()); | |
5532 } | |
5533 } | |
5534 } | |
5535 if (VerifyDuringGC && | |
5536 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
5537 HandleMark hm; // Discard invalid handles created during verification | |
5538 Universe::verify(true); | |
5539 } | |
5540 { | |
5541 TraceTime t("root rescan", PrintGCDetails, false, gclog_or_tty); | |
5542 | |
5543 verify_work_stacks_empty(); | |
5544 | |
5545 gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel. | |
989
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
5546 GenCollectedHeap::StrongRootsScope srs(gch); |
0 | 5547 gch->gen_process_strong_roots(_cmsGen->level(), |
5548 true, // younger gens as roots | |
989
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
5549 false, // use the local StrongRootsScope |
0 | 5550 true, // collecting perm gen |
5551 SharedHeap::ScanningOption(roots_scanning_options()), | |
989
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
5552 &mrias_cl, |
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
5553 true, // walk code active on stacks |
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
5554 NULL); |
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
5555 assert(should_unload_classes() |
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
5556 || (roots_scanning_options() & SharedHeap::SO_CodeCache), |
148e5441d916
6863023: need non-perm oops in code cache for JSR 292
jrose
parents:
798
diff
changeset
|
5557 "if we didn't scan the code cache, we have to be ready to drop nmethods with expired weak oops"); |
0 | 5558 } |
5559 verify_work_stacks_empty(); | |
5560 // Restore evacuated mark words, if any, used for overflow list links | |
5561 if (!CMSOverflowEarlyRestoration) { | |
5562 restore_preserved_marks_if_any(); | |
5563 } | |
5564 verify_overflow_empty(); | |
5565 } | |
5566 | |
5567 //////////////////////////////////////////////////////// | |
5568 // Parallel Reference Processing Task Proxy Class | |
5569 //////////////////////////////////////////////////////// | |
5570 class CMSRefProcTaskProxy: public AbstractGangTask { | |
5571 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; | |
5572 CMSCollector* _collector; | |
5573 CMSBitMap* _mark_bit_map; | |
143
b5489bb705c9
6662086: 6u4+, 7b11+: CMS never clears referents when -XX:+ParallelRefProcEnabled
ysr
parents:
113
diff
changeset
|
5574 const MemRegion _span; |
0 | 5575 OopTaskQueueSet* _task_queues; |
5576 ParallelTaskTerminator _term; | |
5577 ProcessTask& _task; | |
5578 | |
5579 public: | |
5580 CMSRefProcTaskProxy(ProcessTask& task, | |
5581 CMSCollector* collector, | |
5582 const MemRegion& span, | |
5583 CMSBitMap* mark_bit_map, | |
5584 int total_workers, | |
5585 OopTaskQueueSet* task_queues): | |
5586 AbstractGangTask("Process referents by policy in parallel"), | |
5587 _task(task), | |
5588 _collector(collector), _span(span), _mark_bit_map(mark_bit_map), | |
5589 _task_queues(task_queues), | |
5590 _term(total_workers, task_queues) | |
143
b5489bb705c9
6662086: 6u4+, 7b11+: CMS never clears referents when -XX:+ParallelRefProcEnabled
ysr
parents:
113
diff
changeset
|
5591 { |
b5489bb705c9
6662086: 6u4+, 7b11+: CMS never clears referents when -XX:+ParallelRefProcEnabled
ysr
parents:
113
diff
changeset
|
5592 assert(_collector->_span.equals(_span) && !_span.is_empty(), |
b5489bb705c9
6662086: 6u4+, 7b11+: CMS never clears referents when -XX:+ParallelRefProcEnabled
ysr
parents:
113
diff
changeset
|
5593 "Inconsistency in _span"); |
b5489bb705c9
6662086: 6u4+, 7b11+: CMS never clears referents when -XX:+ParallelRefProcEnabled
ysr
parents:
113
diff
changeset
|
5594 } |
0 | 5595 |
5596 OopTaskQueueSet* task_queues() { return _task_queues; } | |
5597 | |
5598 OopTaskQueue* work_queue(int i) { return task_queues()->queue(i); } | |
5599 | |
5600 ParallelTaskTerminator* terminator() { return &_term; } | |
5601 | |
5602 void do_work_steal(int i, | |
5603 CMSParDrainMarkingStackClosure* drain, | |
5604 CMSParKeepAliveClosure* keep_alive, | |
5605 int* seed); | |
5606 | |
5607 virtual void work(int i); | |
5608 }; | |
5609 | |
5610 void CMSRefProcTaskProxy::work(int i) { | |
143
b5489bb705c9
6662086: 6u4+, 7b11+: CMS never clears referents when -XX:+ParallelRefProcEnabled
ysr
parents:
113
diff
changeset
|
5611 assert(_collector->_span.equals(_span), "Inconsistency in _span"); |
0 | 5612 CMSParKeepAliveClosure par_keep_alive(_collector, _span, |
935 | 5613 _mark_bit_map, |
5614 &_collector->_revisitStack, | |
5615 work_queue(i)); | |
0 | 5616 CMSParDrainMarkingStackClosure par_drain_stack(_collector, _span, |
935 | 5617 _mark_bit_map, |
5618 &_collector->_revisitStack, | |
5619 work_queue(i)); | |
143
b5489bb705c9
6662086: 6u4+, 7b11+: CMS never clears referents when -XX:+ParallelRefProcEnabled
ysr
parents:
113
diff
changeset
|
5620 CMSIsAliveClosure is_alive_closure(_span, _mark_bit_map); |
0 | 5621 _task.work(i, is_alive_closure, par_keep_alive, par_drain_stack); |
5622 if (_task.marks_oops_alive()) { | |
5623 do_work_steal(i, &par_drain_stack, &par_keep_alive, | |
5624 _collector->hash_seed(i)); | |
5625 } | |
5626 assert(work_queue(i)->size() == 0, "work_queue should be empty"); | |
5627 assert(_collector->_overflow_list == NULL, "non-empty _overflow_list"); | |
5628 } | |
5629 | |
5630 class CMSRefEnqueueTaskProxy: public AbstractGangTask { | |
5631 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; | |
5632 EnqueueTask& _task; | |
5633 | |
5634 public: | |
5635 CMSRefEnqueueTaskProxy(EnqueueTask& task) | |
5636 : AbstractGangTask("Enqueue reference objects in parallel"), | |
5637 _task(task) | |
5638 { } | |
5639 | |
5640 virtual void work(int i) | |
5641 { | |
5642 _task.work(i); | |
5643 } | |
5644 }; | |
5645 | |
5646 CMSParKeepAliveClosure::CMSParKeepAliveClosure(CMSCollector* collector, | |
935 | 5647 MemRegion span, CMSBitMap* bit_map, CMSMarkStack* revisit_stack, |
5648 OopTaskQueue* work_queue): | |
5649 Par_KlassRememberingOopClosure(collector, NULL, revisit_stack), | |
0 | 5650 _span(span), |
5651 _bit_map(bit_map), | |
5652 _work_queue(work_queue), | |
935 | 5653 _mark_and_push(collector, span, bit_map, revisit_stack, work_queue), |
0 | 5654 _low_water_mark(MIN2((uint)(work_queue->max_elems()/4), |
5655 (uint)(CMSWorkQueueDrainThreshold * ParallelGCThreads))) | |
5656 { } | |
5657 | |
5658 // . see if we can share work_queues with ParNew? XXX | |
5659 void CMSRefProcTaskProxy::do_work_steal(int i, | |
5660 CMSParDrainMarkingStackClosure* drain, | |
5661 CMSParKeepAliveClosure* keep_alive, | |
5662 int* seed) { | |
5663 OopTaskQueue* work_q = work_queue(i); | |
5664 NOT_PRODUCT(int num_steals = 0;) | |
5665 oop obj_to_scan; | |
5666 | |
5667 while (true) { | |
5668 // Completely finish any left over work from (an) earlier round(s) | |
5669 drain->trim_queue(0); | |
679
cea947c8a988
6819891: ParNew: Fix work queue overflow code to deal correctly with +UseCompressedOops
ysr
parents:
628
diff
changeset
|
5670 size_t num_from_overflow_list = MIN2((size_t)(work_q->max_elems() - work_q->size())/4, |
cea947c8a988
6819891: ParNew: Fix work queue overflow code to deal correctly with +UseCompressedOops
ysr
parents:
628
diff
changeset
|
5671 (size_t)ParGCDesiredObjsFromOverflowList); |
0 | 5672 // Now check if there's any work in the overflow list |
5673 if (_collector->par_take_from_overflow_list(num_from_overflow_list, | |
5674 work_q)) { | |
5675 // Found something in global overflow list; | |
5676 // not yet ready to go stealing work from others. | |
5677 // We'd like to assert(work_q->size() != 0, ...) | |
5678 // because we just took work from the overflow list, | |
5679 // but of course we can't, since all of that might have | |
5680 // been already stolen from us. | |
5681 continue; | |
5682 } | |
5683 // Verify that we have no work before we resort to stealing | |
5684 assert(work_q->size() == 0, "Have work, shouldn't steal"); | |
5685 // Try to steal from other queues that have work | |
5686 if (task_queues()->steal(i, seed, /* reference */ obj_to_scan)) { | |
5687 NOT_PRODUCT(num_steals++;) | |
5688 assert(obj_to_scan->is_oop(), "Oops, not an oop!"); | |
5689 assert(_mark_bit_map->isMarked((HeapWord*)obj_to_scan), "Stole an unmarked oop?"); | |
5690 // Do scanning work | |
5691 obj_to_scan->oop_iterate(keep_alive); | |
5692 // Loop around, finish this work, and try to steal some more | |
5693 } else if (terminator()->offer_termination()) { | |
5694 break; // nirvana from the infinite cycle | |
5695 } | |
5696 } | |
5697 NOT_PRODUCT( | |
5698 if (PrintCMSStatistics != 0) { | |
5699 gclog_or_tty->print("\n\t(%d: stole %d oops)", i, num_steals); | |
5700 } | |
5701 ) | |
5702 } | |
5703 | |
5704 void CMSRefProcTaskExecutor::execute(ProcessTask& task) | |
5705 { | |
5706 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
5707 WorkGang* workers = gch->workers(); | |
5708 assert(workers != NULL, "Need parallel worker threads."); | |
5709 int n_workers = workers->total_workers(); | |
5710 CMSRefProcTaskProxy rp_task(task, &_collector, | |
5711 _collector.ref_processor()->span(), | |
5712 _collector.markBitMap(), | |
5713 n_workers, _collector.task_queues()); | |
5714 workers->run_task(&rp_task); | |
5715 } | |
5716 | |
5717 void CMSRefProcTaskExecutor::execute(EnqueueTask& task) | |
5718 { | |
5719 | |
5720 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
5721 WorkGang* workers = gch->workers(); | |
5722 assert(workers != NULL, "Need parallel worker threads."); | |
5723 CMSRefEnqueueTaskProxy enq_task(task); | |
5724 workers->run_task(&enq_task); | |
5725 } | |
5726 | |
5727 void CMSCollector::refProcessingWork(bool asynch, bool clear_all_soft_refs) { | |
5728 | |
5729 ResourceMark rm; | |
5730 HandleMark hm; | |
5731 | |
5732 ReferenceProcessor* rp = ref_processor(); | |
5733 assert(rp->span().equals(_span), "Spans should be equal"); | |
453
c96030fff130
6684579: SoftReference processing can be made more efficient
ysr
parents:
452
diff
changeset
|
5734 assert(!rp->enqueuing_is_done(), "Enqueuing should not be complete"); |
c96030fff130
6684579: SoftReference processing can be made more efficient
ysr
parents:
452
diff
changeset
|
5735 // Process weak references. |
457
27a80744a83b
6778647: snap(), snap_policy() should be renamed setup(), setup_policy()
ysr
parents:
453
diff
changeset
|
5736 rp->setup_policy(clear_all_soft_refs); |
453
c96030fff130
6684579: SoftReference processing can be made more efficient
ysr
parents:
452
diff
changeset
|
5737 verify_work_stacks_empty(); |
c96030fff130
6684579: SoftReference processing can be made more efficient
ysr
parents:
452
diff
changeset
|
5738 |
0 | 5739 CMSKeepAliveClosure cmsKeepAliveClosure(this, _span, &_markBitMap, |
935 | 5740 &_markStack, &_revisitStack, |
5741 false /* !preclean */); | |
0 | 5742 CMSDrainMarkingStackClosure cmsDrainMarkingStackClosure(this, |
5743 _span, &_markBitMap, &_markStack, | |
452
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
5744 &cmsKeepAliveClosure, false /* !preclean */); |
0 | 5745 { |
5746 TraceTime t("weak refs processing", PrintGCDetails, false, gclog_or_tty); | |
5747 if (rp->processing_is_mt()) { | |
5748 CMSRefProcTaskExecutor task_executor(*this); | |
453
c96030fff130
6684579: SoftReference processing can be made more efficient
ysr
parents:
452
diff
changeset
|
5749 rp->process_discovered_references(&_is_alive_closure, |
0 | 5750 &cmsKeepAliveClosure, |
5751 &cmsDrainMarkingStackClosure, | |
5752 &task_executor); | |
5753 } else { | |
453
c96030fff130
6684579: SoftReference processing can be made more efficient
ysr
parents:
452
diff
changeset
|
5754 rp->process_discovered_references(&_is_alive_closure, |
0 | 5755 &cmsKeepAliveClosure, |
5756 &cmsDrainMarkingStackClosure, | |
5757 NULL); | |
5758 } | |
5759 verify_work_stacks_empty(); | |
5760 } | |
5761 | |
94
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
5762 if (should_unload_classes()) { |
0 | 5763 { |
5764 TraceTime t("class unloading", PrintGCDetails, false, gclog_or_tty); | |
5765 | |
5766 // Follow SystemDictionary roots and unload classes | |
5767 bool purged_class = SystemDictionary::do_unloading(&_is_alive_closure); | |
5768 | |
5769 // Follow CodeCache roots and unload any methods marked for unloading | |
5770 CodeCache::do_unloading(&_is_alive_closure, | |
5771 &cmsKeepAliveClosure, | |
5772 purged_class); | |
5773 | |
5774 cmsDrainMarkingStackClosure.do_void(); | |
5775 verify_work_stacks_empty(); | |
5776 | |
5777 // Update subklass/sibling/implementor links in KlassKlass descendants | |
5778 assert(!_revisitStack.isEmpty(), "revisit stack should not be empty"); | |
5779 oop k; | |
5780 while ((k = _revisitStack.pop()) != NULL) { | |
5781 ((Klass*)(oopDesc*)k)->follow_weak_klass_links( | |
5782 &_is_alive_closure, | |
5783 &cmsKeepAliveClosure); | |
5784 } | |
5785 assert(!ClassUnloading || | |
5786 (_markStack.isEmpty() && overflow_list_is_empty()), | |
5787 "Should not have found new reachable objects"); | |
5788 assert(_revisitStack.isEmpty(), "revisit stack should have been drained"); | |
5789 cmsDrainMarkingStackClosure.do_void(); | |
5790 verify_work_stacks_empty(); | |
5791 } | |
5792 | |
5793 { | |
5794 TraceTime t("scrub symbol & string tables", PrintGCDetails, false, gclog_or_tty); | |
5795 // Now clean up stale oops in SymbolTable and StringTable | |
5796 SymbolTable::unlink(&_is_alive_closure); | |
5797 StringTable::unlink(&_is_alive_closure); | |
5798 } | |
5799 } | |
5800 | |
5801 verify_work_stacks_empty(); | |
5802 // Restore any preserved marks as a result of mark stack or | |
5803 // work queue overflow | |
5804 restore_preserved_marks_if_any(); // done single-threaded for now | |
5805 | |
5806 rp->set_enqueuing_is_done(true); | |
5807 if (rp->processing_is_mt()) { | |
5808 CMSRefProcTaskExecutor task_executor(*this); | |
5809 rp->enqueue_discovered_references(&task_executor); | |
5810 } else { | |
5811 rp->enqueue_discovered_references(NULL); | |
5812 } | |
5813 rp->verify_no_references_recorded(); | |
5814 assert(!rp->discovery_enabled(), "should have been disabled"); | |
5815 | |
5816 // JVMTI object tagging is based on JNI weak refs. If any of these | |
5817 // refs were cleared then JVMTI needs to update its maps and | |
5818 // maybe post ObjectFrees to agents. | |
5819 JvmtiExport::cms_ref_processing_epilogue(); | |
5820 } | |
5821 | |
5822 #ifndef PRODUCT | |
5823 void CMSCollector::check_correct_thread_executing() { | |
5824 Thread* t = Thread::current(); | |
5825 // Only the VM thread or the CMS thread should be here. | |
5826 assert(t->is_ConcurrentGC_thread() || t->is_VM_thread(), | |
5827 "Unexpected thread type"); | |
5828 // If this is the vm thread, the foreground process | |
5829 // should not be waiting. Note that _foregroundGCIsActive is | |
5830 // true while the foreground collector is waiting. | |
5831 if (_foregroundGCShouldWait) { | |
5832 // We cannot be the VM thread | |
5833 assert(t->is_ConcurrentGC_thread(), | |
5834 "Should be CMS thread"); | |
5835 } else { | |
5836 // We can be the CMS thread only if we are in a stop-world | |
5837 // phase of CMS collection. | |
5838 if (t->is_ConcurrentGC_thread()) { | |
5839 assert(_collectorState == InitialMarking || | |
5840 _collectorState == FinalMarking, | |
5841 "Should be a stop-world phase"); | |
5842 // The CMS thread should be holding the CMS_token. | |
5843 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
5844 "Potential interference with concurrently " | |
5845 "executing VM thread"); | |
5846 } | |
5847 } | |
5848 } | |
5849 #endif | |
5850 | |
5851 void CMSCollector::sweep(bool asynch) { | |
5852 assert(_collectorState == Sweeping, "just checking"); | |
5853 check_correct_thread_executing(); | |
5854 verify_work_stacks_empty(); | |
5855 verify_overflow_empty(); | |
1145
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
5856 increment_sweep_count(); |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
5857 _inter_sweep_timer.stop(); |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
5858 _inter_sweep_estimate.sample(_inter_sweep_timer.seconds()); |
0 | 5859 size_policy()->avg_cms_free_at_sweep()->sample(_cmsGen->free()); |
5860 | |
5861 // PermGen verification support: If perm gen sweeping is disabled in | |
5862 // this cycle, we preserve the perm gen object "deadness" information | |
5863 // in the perm_gen_verify_bit_map. In order to do that we traverse | |
5864 // all blocks in perm gen and mark all dead objects. | |
94
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
5865 if (verifying() && !should_unload_classes()) { |
0 | 5866 assert(perm_gen_verify_bit_map()->sizeInBits() != 0, |
5867 "Should have already been allocated"); | |
5868 MarkDeadObjectsClosure mdo(this, _permGen->cmsSpace(), | |
5869 markBitMap(), perm_gen_verify_bit_map()); | |
7
2faf283ce688
6621144: CMS: assertion failure "is_cms_thread == Thread::current()->is_ConcurrentGC_thread()"
ysr
parents:
0
diff
changeset
|
5870 if (asynch) { |
2faf283ce688
6621144: CMS: assertion failure "is_cms_thread == Thread::current()->is_ConcurrentGC_thread()"
ysr
parents:
0
diff
changeset
|
5871 CMSTokenSyncWithLocks ts(true, _permGen->freelistLock(), |
2faf283ce688
6621144: CMS: assertion failure "is_cms_thread == Thread::current()->is_ConcurrentGC_thread()"
ysr
parents:
0
diff
changeset
|
5872 bitMapLock()); |
2faf283ce688
6621144: CMS: assertion failure "is_cms_thread == Thread::current()->is_ConcurrentGC_thread()"
ysr
parents:
0
diff
changeset
|
5873 _permGen->cmsSpace()->blk_iterate(&mdo); |
2faf283ce688
6621144: CMS: assertion failure "is_cms_thread == Thread::current()->is_ConcurrentGC_thread()"
ysr
parents:
0
diff
changeset
|
5874 } else { |
2faf283ce688
6621144: CMS: assertion failure "is_cms_thread == Thread::current()->is_ConcurrentGC_thread()"
ysr
parents:
0
diff
changeset
|
5875 // In the case of synchronous sweep, we already have |
2faf283ce688
6621144: CMS: assertion failure "is_cms_thread == Thread::current()->is_ConcurrentGC_thread()"
ysr
parents:
0
diff
changeset
|
5876 // the requisite locks/tokens. |
2faf283ce688
6621144: CMS: assertion failure "is_cms_thread == Thread::current()->is_ConcurrentGC_thread()"
ysr
parents:
0
diff
changeset
|
5877 _permGen->cmsSpace()->blk_iterate(&mdo); |
2faf283ce688
6621144: CMS: assertion failure "is_cms_thread == Thread::current()->is_ConcurrentGC_thread()"
ysr
parents:
0
diff
changeset
|
5878 } |
0 | 5879 } |
5880 | |
1145
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
5881 assert(!_intra_sweep_timer.is_active(), "Should not be active"); |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
5882 _intra_sweep_timer.reset(); |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
5883 _intra_sweep_timer.start(); |
0 | 5884 if (asynch) { |
5885 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
5886 CMSPhaseAccounting pa(this, "sweep", !PrintGCDetails); | |
5887 // First sweep the old gen then the perm gen | |
5888 { | |
5889 CMSTokenSyncWithLocks ts(true, _cmsGen->freelistLock(), | |
5890 bitMapLock()); | |
5891 sweepWork(_cmsGen, asynch); | |
5892 } | |
5893 | |
5894 // Now repeat for perm gen | |
94
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
5895 if (should_unload_classes()) { |
0 | 5896 CMSTokenSyncWithLocks ts(true, _permGen->freelistLock(), |
5897 bitMapLock()); | |
5898 sweepWork(_permGen, asynch); | |
5899 } | |
5900 | |
5901 // Update Universe::_heap_*_at_gc figures. | |
5902 // We need all the free list locks to make the abstract state | |
5903 // transition from Sweeping to Resetting. See detailed note | |
5904 // further below. | |
5905 { | |
5906 CMSTokenSyncWithLocks ts(true, _cmsGen->freelistLock(), | |
5907 _permGen->freelistLock()); | |
5908 // Update heap occupancy information which is used as | |
5909 // input to soft ref clearing policy at the next gc. | |
5910 Universe::update_heap_info_at_gc(); | |
5911 _collectorState = Resizing; | |
5912 } | |
5913 } else { | |
5914 // already have needed locks | |
5915 sweepWork(_cmsGen, asynch); | |
5916 | |
94
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
5917 if (should_unload_classes()) { |
0 | 5918 sweepWork(_permGen, asynch); |
5919 } | |
5920 // Update heap occupancy information which is used as | |
5921 // input to soft ref clearing policy at the next gc. | |
5922 Universe::update_heap_info_at_gc(); | |
5923 _collectorState = Resizing; | |
5924 } | |
5925 verify_work_stacks_empty(); | |
5926 verify_overflow_empty(); | |
5927 | |
1145
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
5928 _intra_sweep_timer.stop(); |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
5929 _intra_sweep_estimate.sample(_intra_sweep_timer.seconds()); |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
5930 |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
5931 _inter_sweep_timer.reset(); |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
5932 _inter_sweep_timer.start(); |
0 | 5933 |
5934 update_time_of_last_gc(os::javaTimeMillis()); | |
5935 | |
5936 // NOTE on abstract state transitions: | |
5937 // Mutators allocate-live and/or mark the mod-union table dirty | |
5938 // based on the state of the collection. The former is done in | |
5939 // the interval [Marking, Sweeping] and the latter in the interval | |
5940 // [Marking, Sweeping). Thus the transitions into the Marking state | |
5941 // and out of the Sweeping state must be synchronously visible | |
5942 // globally to the mutators. | |
5943 // The transition into the Marking state happens with the world | |
5944 // stopped so the mutators will globally see it. Sweeping is | |
5945 // done asynchronously by the background collector so the transition | |
5946 // from the Sweeping state to the Resizing state must be done | |
5947 // under the freelistLock (as is the check for whether to | |
5948 // allocate-live and whether to dirty the mod-union table). | |
5949 assert(_collectorState == Resizing, "Change of collector state to" | |
5950 " Resizing must be done under the freelistLocks (plural)"); | |
5951 | |
5952 // Now that sweeping has been completed, if the GCH's | |
5953 // incremental_collection_will_fail flag is set, clear it, | |
5954 // thus inviting a younger gen collection to promote into | |
5955 // this generation. If such a promotion may still fail, | |
5956 // the flag will be set again when a young collection is | |
5957 // attempted. | |
5958 // I think the incremental_collection_will_fail flag's use | |
5959 // is specific to a 2 generation collection policy, so i'll | |
5960 // assert that that's the configuration we are operating within. | |
5961 // The use of the flag can and should be generalized appropriately | |
5962 // in the future to deal with a general n-generation system. | |
5963 | |
5964 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
5965 assert(gch->collector_policy()->is_two_generation_policy(), | |
5966 "Resetting of incremental_collection_will_fail flag" | |
5967 " may be incorrect otherwise"); | |
5968 gch->clear_incremental_collection_will_fail(); | |
5969 gch->update_full_collections_completed(_collection_count_start); | |
5970 } | |
5971 | |
5972 // FIX ME!!! Looks like this belongs in CFLSpace, with | |
5973 // CMSGen merely delegating to it. | |
5974 void ConcurrentMarkSweepGeneration::setNearLargestChunk() { | |
1145
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
5975 double nearLargestPercent = FLSLargestBlockCoalesceProximity; |
0 | 5976 HeapWord* minAddr = _cmsSpace->bottom(); |
5977 HeapWord* largestAddr = | |
5978 (HeapWord*) _cmsSpace->dictionary()->findLargestDict(); | |
1145
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
5979 if (largestAddr == NULL) { |
0 | 5980 // The dictionary appears to be empty. In this case |
5981 // try to coalesce at the end of the heap. | |
5982 largestAddr = _cmsSpace->end(); | |
5983 } | |
5984 size_t largestOffset = pointer_delta(largestAddr, minAddr); | |
5985 size_t nearLargestOffset = | |
5986 (size_t)((double)largestOffset * nearLargestPercent) - MinChunkSize; | |
1145
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
5987 if (PrintFLSStatistics != 0) { |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
5988 gclog_or_tty->print_cr( |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
5989 "CMS: Large Block: " PTR_FORMAT ";" |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
5990 " Proximity: " PTR_FORMAT " -> " PTR_FORMAT, |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
5991 largestAddr, |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
5992 _cmsSpace->nearLargestChunk(), minAddr + nearLargestOffset); |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
5993 } |
0 | 5994 _cmsSpace->set_nearLargestChunk(minAddr + nearLargestOffset); |
5995 } | |
5996 | |
5997 bool ConcurrentMarkSweepGeneration::isNearLargestChunk(HeapWord* addr) { | |
5998 return addr >= _cmsSpace->nearLargestChunk(); | |
5999 } | |
6000 | |
6001 FreeChunk* ConcurrentMarkSweepGeneration::find_chunk_at_end() { | |
6002 return _cmsSpace->find_chunk_at_end(); | |
6003 } | |
6004 | |
6005 void ConcurrentMarkSweepGeneration::update_gc_stats(int current_level, | |
6006 bool full) { | |
6007 // The next lower level has been collected. Gather any statistics | |
6008 // that are of interest at this point. | |
6009 if (!full && (current_level + 1) == level()) { | |
6010 // Gather statistics on the young generation collection. | |
6011 collector()->stats().record_gc0_end(used()); | |
6012 } | |
6013 } | |
6014 | |
6015 CMSAdaptiveSizePolicy* ConcurrentMarkSweepGeneration::size_policy() { | |
6016 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
6017 assert(gch->kind() == CollectedHeap::GenCollectedHeap, | |
6018 "Wrong type of heap"); | |
6019 CMSAdaptiveSizePolicy* sp = (CMSAdaptiveSizePolicy*) | |
6020 gch->gen_policy()->size_policy(); | |
6021 assert(sp->is_gc_cms_adaptive_size_policy(), | |
6022 "Wrong type of size policy"); | |
6023 return sp; | |
6024 } | |
6025 | |
6026 void ConcurrentMarkSweepGeneration::rotate_debug_collection_type() { | |
6027 if (PrintGCDetails && Verbose) { | |
6028 gclog_or_tty->print("Rotate from %d ", _debug_collection_type); | |
6029 } | |
6030 _debug_collection_type = (CollectionTypes) (_debug_collection_type + 1); | |
6031 _debug_collection_type = | |
6032 (CollectionTypes) (_debug_collection_type % Unknown_collection_type); | |
6033 if (PrintGCDetails && Verbose) { | |
6034 gclog_or_tty->print_cr("to %d ", _debug_collection_type); | |
6035 } | |
6036 } | |
6037 | |
6038 void CMSCollector::sweepWork(ConcurrentMarkSweepGeneration* gen, | |
6039 bool asynch) { | |
6040 // We iterate over the space(s) underlying this generation, | |
6041 // checking the mark bit map to see if the bits corresponding | |
6042 // to specific blocks are marked or not. Blocks that are | |
6043 // marked are live and are not swept up. All remaining blocks | |
6044 // are swept up, with coalescing on-the-fly as we sweep up | |
6045 // contiguous free and/or garbage blocks: | |
6046 // We need to ensure that the sweeper synchronizes with allocators | |
6047 // and stop-the-world collectors. In particular, the following | |
6048 // locks are used: | |
6049 // . CMS token: if this is held, a stop the world collection cannot occur | |
6050 // . freelistLock: if this is held no allocation can occur from this | |
6051 // generation by another thread | |
6052 // . bitMapLock: if this is held, no other thread can access or update | |
6053 // | |
6054 | |
6055 // Note that we need to hold the freelistLock if we use | |
6056 // block iterate below; else the iterator might go awry if | |
6057 // a mutator (or promotion) causes block contents to change | |
6058 // (for instance if the allocator divvies up a block). | |
6059 // If we hold the free list lock, for all practical purposes | |
6060 // young generation GC's can't occur (they'll usually need to | |
6061 // promote), so we might as well prevent all young generation | |
6062 // GC's while we do a sweeping step. For the same reason, we might | |
6063 // as well take the bit map lock for the entire duration | |
6064 | |
6065 // check that we hold the requisite locks | |
6066 assert(have_cms_token(), "Should hold cms token"); | |
6067 assert( (asynch && ConcurrentMarkSweepThread::cms_thread_has_cms_token()) | |
6068 || (!asynch && ConcurrentMarkSweepThread::vm_thread_has_cms_token()), | |
6069 "Should possess CMS token to sweep"); | |
6070 assert_lock_strong(gen->freelistLock()); | |
6071 assert_lock_strong(bitMapLock()); | |
6072 | |
1145
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
6073 assert(!_inter_sweep_timer.is_active(), "Was switched off in an outer context"); |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
6074 assert(_intra_sweep_timer.is_active(), "Was switched on in an outer context"); |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
6075 gen->cmsSpace()->beginSweepFLCensus((float)(_inter_sweep_timer.seconds()), |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
6076 _inter_sweep_estimate.padded_average(), |
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
6077 _intra_sweep_estimate.padded_average()); |
0 | 6078 gen->setNearLargestChunk(); |
6079 | |
6080 { | |
6081 SweepClosure sweepClosure(this, gen, &_markBitMap, | |
6082 CMSYield && asynch); | |
6083 gen->cmsSpace()->blk_iterate_careful(&sweepClosure); | |
6084 // We need to free-up/coalesce garbage/blocks from a | |
6085 // co-terminal free run. This is done in the SweepClosure | |
6086 // destructor; so, do not remove this scope, else the | |
6087 // end-of-sweep-census below will be off by a little bit. | |
6088 } | |
6089 gen->cmsSpace()->sweep_completed(); | |
1145
e018e6884bd8
6631166: CMS: better heuristics when combatting fragmentation
ysr
parents:
1085
diff
changeset
|
6090 gen->cmsSpace()->endSweepFLCensus(sweep_count()); |
94
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
6091 if (should_unload_classes()) { // unloaded classes this cycle, |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
6092 _concurrent_cycles_since_last_unload = 0; // ... reset count |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
6093 } else { // did not unload classes, |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
6094 _concurrent_cycles_since_last_unload++; // ... increment count |
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
6095 } |
0 | 6096 } |
6097 | |
6098 // Reset CMS data structures (for now just the marking bit map) | |
6099 // preparatory for the next cycle. | |
6100 void CMSCollector::reset(bool asynch) { | |
6101 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
6102 CMSAdaptiveSizePolicy* sp = size_policy(); | |
6103 AdaptiveSizePolicyOutput(sp, gch->total_collections()); | |
6104 if (asynch) { | |
6105 CMSTokenSyncWithLocks ts(true, bitMapLock()); | |
6106 | |
6107 // If the state is not "Resetting", the foreground thread | |
6108 // has done a collection and the resetting. | |
6109 if (_collectorState != Resetting) { | |
6110 assert(_collectorState == Idling, "The state should only change" | |
6111 " because the foreground collector has finished the collection"); | |
6112 return; | |
6113 } | |
6114 | |
6115 // Clear the mark bitmap (no grey objects to start with) | |
6116 // for the next cycle. | |
6117 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
6118 CMSPhaseAccounting cmspa(this, "reset", !PrintGCDetails); | |
6119 | |
6120 HeapWord* curAddr = _markBitMap.startWord(); | |
6121 while (curAddr < _markBitMap.endWord()) { | |
6122 size_t remaining = pointer_delta(_markBitMap.endWord(), curAddr); | |
6123 MemRegion chunk(curAddr, MIN2(CMSBitMapYieldQuantum, remaining)); | |
6124 _markBitMap.clear_large_range(chunk); | |
6125 if (ConcurrentMarkSweepThread::should_yield() && | |
6126 !foregroundGCIsActive() && | |
6127 CMSYield) { | |
6128 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
6129 "CMS thread should hold CMS token"); | |
6130 assert_lock_strong(bitMapLock()); | |
6131 bitMapLock()->unlock(); | |
6132 ConcurrentMarkSweepThread::desynchronize(true); | |
6133 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
6134 stopTimer(); | |
6135 if (PrintCMSStatistics != 0) { | |
6136 incrementYields(); | |
6137 } | |
6138 icms_wait(); | |
6139 | |
6140 // See the comment in coordinator_yield() | |
6141 for (unsigned i = 0; i < CMSYieldSleepCount && | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6142 ConcurrentMarkSweepThread::should_yield() && |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6143 !CMSCollector::foregroundGCIsActive(); ++i) { |
0 | 6144 os::sleep(Thread::current(), 1, false); |
6145 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
6146 } | |
6147 | |
6148 ConcurrentMarkSweepThread::synchronize(true); | |
6149 bitMapLock()->lock_without_safepoint_check(); | |
6150 startTimer(); | |
6151 } | |
6152 curAddr = chunk.end(); | |
6153 } | |
1387
0bfd3fb24150
6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
jmasa
parents:
1289
diff
changeset
|
6154 // A successful mostly concurrent collection has been done. |
0bfd3fb24150
6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
jmasa
parents:
1289
diff
changeset
|
6155 // Because only the full (i.e., concurrent mode failure) collections |
0bfd3fb24150
6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
jmasa
parents:
1289
diff
changeset
|
6156 // are being measured for gc overhead limits, clean the "near" flag |
0bfd3fb24150
6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
jmasa
parents:
1289
diff
changeset
|
6157 // and count. |
0bfd3fb24150
6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
jmasa
parents:
1289
diff
changeset
|
6158 sp->reset_gc_overhead_limit_count(); |
0 | 6159 _collectorState = Idling; |
6160 } else { | |
6161 // already have the lock | |
6162 assert(_collectorState == Resetting, "just checking"); | |
6163 assert_lock_strong(bitMapLock()); | |
6164 _markBitMap.clear_all(); | |
6165 _collectorState = Idling; | |
6166 } | |
6167 | |
6168 // Stop incremental mode after a cycle completes, so that any future cycles | |
6169 // are triggered by allocation. | |
6170 stop_icms(); | |
6171 | |
6172 NOT_PRODUCT( | |
6173 if (RotateCMSCollectionTypes) { | |
6174 _cmsGen->rotate_debug_collection_type(); | |
6175 } | |
6176 ) | |
6177 } | |
6178 | |
6179 void CMSCollector::do_CMS_operation(CMS_op_type op) { | |
6180 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps); | |
6181 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
6182 TraceTime t("GC", PrintGC, !PrintGCDetails, gclog_or_tty); | |
6183 TraceCollectorStats tcs(counters()); | |
6184 | |
6185 switch (op) { | |
6186 case CMS_op_checkpointRootsInitial: { | |
6187 checkpointRootsInitial(true); // asynch | |
6188 if (PrintGC) { | |
6189 _cmsGen->printOccupancy("initial-mark"); | |
6190 } | |
6191 break; | |
6192 } | |
6193 case CMS_op_checkpointRootsFinal: { | |
6194 checkpointRootsFinal(true, // asynch | |
6195 false, // !clear_all_soft_refs | |
6196 false); // !init_mark_was_synchronous | |
6197 if (PrintGC) { | |
6198 _cmsGen->printOccupancy("remark"); | |
6199 } | |
6200 break; | |
6201 } | |
6202 default: | |
6203 fatal("No such CMS_op"); | |
6204 } | |
6205 } | |
6206 | |
6207 #ifndef PRODUCT | |
6208 size_t const CMSCollector::skip_header_HeapWords() { | |
6209 return FreeChunk::header_size(); | |
6210 } | |
6211 | |
6212 // Try and collect here conditions that should hold when | |
6213 // CMS thread is exiting. The idea is that the foreground GC | |
6214 // thread should not be blocked if it wants to terminate | |
6215 // the CMS thread and yet continue to run the VM for a while | |
6216 // after that. | |
6217 void CMSCollector::verify_ok_to_terminate() const { | |
6218 assert(Thread::current()->is_ConcurrentGC_thread(), | |
6219 "should be called by CMS thread"); | |
6220 assert(!_foregroundGCShouldWait, "should be false"); | |
6221 // We could check here that all the various low-level locks | |
6222 // are not held by the CMS thread, but that is overkill; see | |
6223 // also CMSThread::verify_ok_to_terminate() where the CGC_lock | |
6224 // is checked. | |
6225 } | |
6226 #endif | |
6227 | |
6228 size_t CMSCollector::block_size_using_printezis_bits(HeapWord* addr) const { | |
453
c96030fff130
6684579: SoftReference processing can be made more efficient
ysr
parents:
452
diff
changeset
|
6229 assert(_markBitMap.isMarked(addr) && _markBitMap.isMarked(addr + 1), |
c96030fff130
6684579: SoftReference processing can be made more efficient
ysr
parents:
452
diff
changeset
|
6230 "missing Printezis mark?"); |
0 | 6231 HeapWord* nextOneAddr = _markBitMap.getNextMarkedWordAddress(addr + 2); |
6232 size_t size = pointer_delta(nextOneAddr + 1, addr); | |
6233 assert(size == CompactibleFreeListSpace::adjustObjectSize(size), | |
6234 "alignment problem"); | |
6235 assert(size >= 3, "Necessary for Printezis marks to work"); | |
6236 return size; | |
6237 } | |
6238 | |
6239 // A variant of the above (block_size_using_printezis_bits()) except | |
6240 // that we return 0 if the P-bits are not yet set. | |
6241 size_t CMSCollector::block_size_if_printezis_bits(HeapWord* addr) const { | |
6242 if (_markBitMap.isMarked(addr)) { | |
6243 assert(_markBitMap.isMarked(addr + 1), "Missing Printezis bit?"); | |
6244 HeapWord* nextOneAddr = _markBitMap.getNextMarkedWordAddress(addr + 2); | |
6245 size_t size = pointer_delta(nextOneAddr + 1, addr); | |
6246 assert(size == CompactibleFreeListSpace::adjustObjectSize(size), | |
6247 "alignment problem"); | |
6248 assert(size >= 3, "Necessary for Printezis marks to work"); | |
6249 return size; | |
6250 } else { | |
6251 assert(!_markBitMap.isMarked(addr + 1), "Bit map inconsistency?"); | |
6252 return 0; | |
6253 } | |
6254 } | |
6255 | |
6256 HeapWord* CMSCollector::next_card_start_after_block(HeapWord* addr) const { | |
6257 size_t sz = 0; | |
6258 oop p = (oop)addr; | |
187 | 6259 if (p->klass_or_null() != NULL && p->is_parsable()) { |
0 | 6260 sz = CompactibleFreeListSpace::adjustObjectSize(p->size()); |
6261 } else { | |
6262 sz = block_size_using_printezis_bits(addr); | |
6263 } | |
6264 assert(sz > 0, "size must be nonzero"); | |
6265 HeapWord* next_block = addr + sz; | |
6266 HeapWord* next_card = (HeapWord*)round_to((uintptr_t)next_block, | |
6267 CardTableModRefBS::card_size); | |
6268 assert(round_down((uintptr_t)addr, CardTableModRefBS::card_size) < | |
6269 round_down((uintptr_t)next_card, CardTableModRefBS::card_size), | |
6270 "must be different cards"); | |
6271 return next_card; | |
6272 } | |
6273 | |
6274 | |
6275 // CMS Bit Map Wrapper ///////////////////////////////////////// | |
6276 | |
6277 // Construct a CMS bit map infrastructure, but don't create the | |
6278 // bit vector itself. That is done by a separate call CMSBitMap::allocate() | |
6279 // further below. | |
6280 CMSBitMap::CMSBitMap(int shifter, int mutex_rank, const char* mutex_name): | |
342
37f87013dfd8
6711316: Open source the Garbage-First garbage collector
ysr
parents:
143
diff
changeset
|
6281 _bm(), |
0 | 6282 _shifter(shifter), |
6283 _lock(mutex_rank >= 0 ? new Mutex(mutex_rank, mutex_name, true) : NULL) | |
6284 { | |
6285 _bmStartWord = 0; | |
6286 _bmWordSize = 0; | |
6287 } | |
6288 | |
6289 bool CMSBitMap::allocate(MemRegion mr) { | |
6290 _bmStartWord = mr.start(); | |
6291 _bmWordSize = mr.word_size(); | |
6292 ReservedSpace brs(ReservedSpace::allocation_align_size_up( | |
6293 (_bmWordSize >> (_shifter + LogBitsPerByte)) + 1)); | |
6294 if (!brs.is_reserved()) { | |
6295 warning("CMS bit map allocation failure"); | |
6296 return false; | |
6297 } | |
6298 // For now we'll just commit all of the bit map up fromt. | |
6299 // Later on we'll try to be more parsimonious with swap. | |
6300 if (!_virtual_space.initialize(brs, brs.size())) { | |
6301 warning("CMS bit map backing store failure"); | |
6302 return false; | |
6303 } | |
6304 assert(_virtual_space.committed_size() == brs.size(), | |
6305 "didn't reserve backing store for all of CMS bit map?"); | |
342
37f87013dfd8
6711316: Open source the Garbage-First garbage collector
ysr
parents:
143
diff
changeset
|
6306 _bm.set_map((BitMap::bm_word_t*)_virtual_space.low()); |
0 | 6307 assert(_virtual_space.committed_size() << (_shifter + LogBitsPerByte) >= |
6308 _bmWordSize, "inconsistency in bit map sizing"); | |
6309 _bm.set_size(_bmWordSize >> _shifter); | |
6310 | |
6311 // bm.clear(); // can we rely on getting zero'd memory? verify below | |
6312 assert(isAllClear(), | |
6313 "Expected zero'd memory from ReservedSpace constructor"); | |
6314 assert(_bm.size() == heapWordDiffToOffsetDiff(sizeInWords()), | |
6315 "consistency check"); | |
6316 return true; | |
6317 } | |
6318 | |
6319 void CMSBitMap::dirty_range_iterate_clear(MemRegion mr, MemRegionClosure* cl) { | |
6320 HeapWord *next_addr, *end_addr, *last_addr; | |
6321 assert_locked(); | |
6322 assert(covers(mr), "out-of-range error"); | |
6323 // XXX assert that start and end are appropriately aligned | |
6324 for (next_addr = mr.start(), end_addr = mr.end(); | |
6325 next_addr < end_addr; next_addr = last_addr) { | |
6326 MemRegion dirty_region = getAndClearMarkedRegion(next_addr, end_addr); | |
6327 last_addr = dirty_region.end(); | |
6328 if (!dirty_region.is_empty()) { | |
6329 cl->do_MemRegion(dirty_region); | |
6330 } else { | |
6331 assert(last_addr == end_addr, "program logic"); | |
6332 return; | |
6333 } | |
6334 } | |
6335 } | |
6336 | |
6337 #ifndef PRODUCT | |
6338 void CMSBitMap::assert_locked() const { | |
6339 CMSLockVerifier::assert_locked(lock()); | |
6340 } | |
6341 | |
6342 bool CMSBitMap::covers(MemRegion mr) const { | |
6343 // assert(_bm.map() == _virtual_space.low(), "map inconsistency"); | |
6344 assert((size_t)_bm.size() == (_bmWordSize >> _shifter), | |
6345 "size inconsistency"); | |
6346 return (mr.start() >= _bmStartWord) && | |
6347 (mr.end() <= endWord()); | |
6348 } | |
6349 | |
6350 bool CMSBitMap::covers(HeapWord* start, size_t size) const { | |
6351 return (start >= _bmStartWord && (start + size) <= endWord()); | |
6352 } | |
6353 | |
6354 void CMSBitMap::verifyNoOneBitsInRange(HeapWord* left, HeapWord* right) { | |
6355 // verify that there are no 1 bits in the interval [left, right) | |
6356 FalseBitMapClosure falseBitMapClosure; | |
6357 iterate(&falseBitMapClosure, left, right); | |
6358 } | |
6359 | |
6360 void CMSBitMap::region_invariant(MemRegion mr) | |
6361 { | |
6362 assert_locked(); | |
6363 // mr = mr.intersection(MemRegion(_bmStartWord, _bmWordSize)); | |
6364 assert(!mr.is_empty(), "unexpected empty region"); | |
6365 assert(covers(mr), "mr should be covered by bit map"); | |
6366 // convert address range into offset range | |
6367 size_t start_ofs = heapWordToOffset(mr.start()); | |
6368 // Make sure that end() is appropriately aligned | |
6369 assert(mr.end() == (HeapWord*)round_to((intptr_t)mr.end(), | |
6370 (1 << (_shifter+LogHeapWordSize))), | |
6371 "Misaligned mr.end()"); | |
6372 size_t end_ofs = heapWordToOffset(mr.end()); | |
6373 assert(end_ofs > start_ofs, "Should mark at least one bit"); | |
6374 } | |
6375 | |
6376 #endif | |
6377 | |
6378 bool CMSMarkStack::allocate(size_t size) { | |
6379 // allocate a stack of the requisite depth | |
6380 ReservedSpace rs(ReservedSpace::allocation_align_size_up( | |
6381 size * sizeof(oop))); | |
6382 if (!rs.is_reserved()) { | |
6383 warning("CMSMarkStack allocation failure"); | |
6384 return false; | |
6385 } | |
6386 if (!_virtual_space.initialize(rs, rs.size())) { | |
6387 warning("CMSMarkStack backing store failure"); | |
6388 return false; | |
6389 } | |
6390 assert(_virtual_space.committed_size() == rs.size(), | |
6391 "didn't reserve backing store for all of CMS stack?"); | |
6392 _base = (oop*)(_virtual_space.low()); | |
6393 _index = 0; | |
6394 _capacity = size; | |
6395 NOT_PRODUCT(_max_depth = 0); | |
6396 return true; | |
6397 } | |
6398 | |
6399 // XXX FIX ME !!! In the MT case we come in here holding a | |
6400 // leaf lock. For printing we need to take a further lock | |
6401 // which has lower rank. We need to recallibrate the two | |
6402 // lock-ranks involved in order to be able to rpint the | |
6403 // messages below. (Or defer the printing to the caller. | |
6404 // For now we take the expedient path of just disabling the | |
6405 // messages for the problematic case.) | |
6406 void CMSMarkStack::expand() { | |
1284 | 6407 assert(_capacity <= MarkStackSizeMax, "stack bigger than permitted"); |
6408 if (_capacity == MarkStackSizeMax) { | |
0 | 6409 if (_hit_limit++ == 0 && !CMSConcurrentMTEnabled && PrintGCDetails) { |
6410 // We print a warning message only once per CMS cycle. | |
6411 gclog_or_tty->print_cr(" (benign) Hit CMSMarkStack max size limit"); | |
6412 } | |
6413 return; | |
6414 } | |
6415 // Double capacity if possible | |
1284 | 6416 size_t new_capacity = MIN2(_capacity*2, MarkStackSizeMax); |
0 | 6417 // Do not give up existing stack until we have managed to |
6418 // get the double capacity that we desired. | |
6419 ReservedSpace rs(ReservedSpace::allocation_align_size_up( | |
6420 new_capacity * sizeof(oop))); | |
6421 if (rs.is_reserved()) { | |
6422 // Release the backing store associated with old stack | |
6423 _virtual_space.release(); | |
6424 // Reinitialize virtual space for new stack | |
6425 if (!_virtual_space.initialize(rs, rs.size())) { | |
6426 fatal("Not enough swap for expanded marking stack"); | |
6427 } | |
6428 _base = (oop*)(_virtual_space.low()); | |
6429 _index = 0; | |
6430 _capacity = new_capacity; | |
6431 } else if (_failed_double++ == 0 && !CMSConcurrentMTEnabled && PrintGCDetails) { | |
6432 // Failed to double capacity, continue; | |
6433 // we print a detail message only once per CMS cycle. | |
6434 gclog_or_tty->print(" (benign) Failed to expand marking stack from "SIZE_FORMAT"K to " | |
6435 SIZE_FORMAT"K", | |
6436 _capacity / K, new_capacity / K); | |
6437 } | |
6438 } | |
6439 | |
6440 | |
6441 // Closures | |
6442 // XXX: there seems to be a lot of code duplication here; | |
6443 // should refactor and consolidate common code. | |
6444 | |
6445 // This closure is used to mark refs into the CMS generation in | |
6446 // the CMS bit map. Called at the first checkpoint. This closure | |
6447 // assumes that we do not need to re-mark dirty cards; if the CMS | |
6448 // generation on which this is used is not an oldest (modulo perm gen) | |
6449 // generation then this will lose younger_gen cards! | |
6450 | |
6451 MarkRefsIntoClosure::MarkRefsIntoClosure( | |
994
753cf9794df9
6885169: merge of 4957990 and 6863023 causes conflict on do_nmethods
jrose
parents:
993
diff
changeset
|
6452 MemRegion span, CMSBitMap* bitMap): |
0 | 6453 _span(span), |
994
753cf9794df9
6885169: merge of 4957990 and 6863023 causes conflict on do_nmethods
jrose
parents:
993
diff
changeset
|
6454 _bitMap(bitMap) |
0 | 6455 { |
6456 assert(_ref_processor == NULL, "deliberately left NULL"); | |
6457 assert(_bitMap->covers(_span), "_bitMap/_span mismatch"); | |
6458 } | |
6459 | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6460 void MarkRefsIntoClosure::do_oop(oop obj) { |
0 | 6461 // if p points into _span, then mark corresponding bit in _markBitMap |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6462 assert(obj->is_oop(), "expected an oop"); |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6463 HeapWord* addr = (HeapWord*)obj; |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6464 if (_span.contains(addr)) { |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6465 // this should be made more efficient |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6466 _bitMap->mark(addr); |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6467 } |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6468 } |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6469 |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6470 void MarkRefsIntoClosure::do_oop(oop* p) { MarkRefsIntoClosure::do_oop_work(p); } |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6471 void MarkRefsIntoClosure::do_oop(narrowOop* p) { MarkRefsIntoClosure::do_oop_work(p); } |
0 | 6472 |
6473 // A variant of the above, used for CMS marking verification. | |
6474 MarkRefsIntoVerifyClosure::MarkRefsIntoVerifyClosure( | |
994
753cf9794df9
6885169: merge of 4957990 and 6863023 causes conflict on do_nmethods
jrose
parents:
993
diff
changeset
|
6475 MemRegion span, CMSBitMap* verification_bm, CMSBitMap* cms_bm): |
0 | 6476 _span(span), |
6477 _verification_bm(verification_bm), | |
994
753cf9794df9
6885169: merge of 4957990 and 6863023 causes conflict on do_nmethods
jrose
parents:
993
diff
changeset
|
6478 _cms_bm(cms_bm) |
753cf9794df9
6885169: merge of 4957990 and 6863023 causes conflict on do_nmethods
jrose
parents:
993
diff
changeset
|
6479 { |
0 | 6480 assert(_ref_processor == NULL, "deliberately left NULL"); |
6481 assert(_verification_bm->covers(_span), "_verification_bm/_span mismatch"); | |
6482 } | |
6483 | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6484 void MarkRefsIntoVerifyClosure::do_oop(oop obj) { |
0 | 6485 // if p points into _span, then mark corresponding bit in _markBitMap |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6486 assert(obj->is_oop(), "expected an oop"); |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6487 HeapWord* addr = (HeapWord*)obj; |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6488 if (_span.contains(addr)) { |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6489 _verification_bm->mark(addr); |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6490 if (!_cms_bm->isMarked(addr)) { |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6491 oop(addr)->print(); |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6492 gclog_or_tty->print_cr(" (" INTPTR_FORMAT " should have been marked)", addr); |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6493 fatal("... aborting"); |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6494 } |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6495 } |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6496 } |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6497 |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6498 void MarkRefsIntoVerifyClosure::do_oop(oop* p) { MarkRefsIntoVerifyClosure::do_oop_work(p); } |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6499 void MarkRefsIntoVerifyClosure::do_oop(narrowOop* p) { MarkRefsIntoVerifyClosure::do_oop_work(p); } |
0 | 6500 |
6501 ////////////////////////////////////////////////// | |
6502 // MarkRefsIntoAndScanClosure | |
6503 ////////////////////////////////////////////////// | |
6504 | |
6505 MarkRefsIntoAndScanClosure::MarkRefsIntoAndScanClosure(MemRegion span, | |
6506 ReferenceProcessor* rp, | |
6507 CMSBitMap* bit_map, | |
6508 CMSBitMap* mod_union_table, | |
6509 CMSMarkStack* mark_stack, | |
6510 CMSMarkStack* revisit_stack, | |
6511 CMSCollector* collector, | |
6512 bool should_yield, | |
6513 bool concurrent_precleaning): | |
6514 _collector(collector), | |
6515 _span(span), | |
6516 _bit_map(bit_map), | |
6517 _mark_stack(mark_stack), | |
6518 _pushAndMarkClosure(collector, span, rp, bit_map, mod_union_table, | |
6519 mark_stack, revisit_stack, concurrent_precleaning), | |
6520 _yield(should_yield), | |
6521 _concurrent_precleaning(concurrent_precleaning), | |
6522 _freelistLock(NULL) | |
6523 { | |
6524 _ref_processor = rp; | |
6525 assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL"); | |
6526 } | |
6527 | |
6528 // This closure is used to mark refs into the CMS generation at the | |
6529 // second (final) checkpoint, and to scan and transitively follow | |
6530 // the unmarked oops. It is also used during the concurrent precleaning | |
6531 // phase while scanning objects on dirty cards in the CMS generation. | |
6532 // The marks are made in the marking bit map and the marking stack is | |
6533 // used for keeping the (newly) grey objects during the scan. | |
6534 // The parallel version (Par_...) appears further below. | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6535 void MarkRefsIntoAndScanClosure::do_oop(oop obj) { |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6536 if (obj != NULL) { |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6537 assert(obj->is_oop(), "expected an oop"); |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6538 HeapWord* addr = (HeapWord*)obj; |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6539 assert(_mark_stack->isEmpty(), "pre-condition (eager drainage)"); |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6540 assert(_collector->overflow_list_is_empty(), |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6541 "overflow list should be empty"); |
0 | 6542 if (_span.contains(addr) && |
6543 !_bit_map->isMarked(addr)) { | |
6544 // mark bit map (object is now grey) | |
6545 _bit_map->mark(addr); | |
6546 // push on marking stack (stack should be empty), and drain the | |
6547 // stack by applying this closure to the oops in the oops popped | |
6548 // from the stack (i.e. blacken the grey objects) | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6549 bool res = _mark_stack->push(obj); |
0 | 6550 assert(res, "Should have space to push on empty stack"); |
6551 do { | |
6552 oop new_oop = _mark_stack->pop(); | |
6553 assert(new_oop != NULL && new_oop->is_oop(), "Expected an oop"); | |
6554 assert(new_oop->is_parsable(), "Found unparsable oop"); | |
6555 assert(_bit_map->isMarked((HeapWord*)new_oop), | |
6556 "only grey objects on this stack"); | |
6557 // iterate over the oops in this oop, marking and pushing | |
6558 // the ones in CMS heap (i.e. in _span). | |
6559 new_oop->oop_iterate(&_pushAndMarkClosure); | |
6560 // check if it's time to yield | |
6561 do_yield_check(); | |
6562 } while (!_mark_stack->isEmpty() || | |
6563 (!_concurrent_precleaning && take_from_overflow_list())); | |
6564 // if marking stack is empty, and we are not doing this | |
6565 // during precleaning, then check the overflow list | |
6566 } | |
6567 assert(_mark_stack->isEmpty(), "post-condition (eager drainage)"); | |
6568 assert(_collector->overflow_list_is_empty(), | |
6569 "overflow list was drained above"); | |
6570 // We could restore evacuated mark words, if any, used for | |
6571 // overflow list links here because the overflow list is | |
6572 // provably empty here. That would reduce the maximum | |
6573 // size requirements for preserved_{oop,mark}_stack. | |
6574 // But we'll just postpone it until we are all done | |
6575 // so we can just stream through. | |
6576 if (!_concurrent_precleaning && CMSOverflowEarlyRestoration) { | |
6577 _collector->restore_preserved_marks_if_any(); | |
6578 assert(_collector->no_preserved_marks(), "No preserved marks"); | |
6579 } | |
6580 assert(!CMSOverflowEarlyRestoration || _collector->no_preserved_marks(), | |
6581 "All preserved marks should have been restored above"); | |
6582 } | |
6583 } | |
6584 | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6585 void MarkRefsIntoAndScanClosure::do_oop(oop* p) { MarkRefsIntoAndScanClosure::do_oop_work(p); } |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6586 void MarkRefsIntoAndScanClosure::do_oop(narrowOop* p) { MarkRefsIntoAndScanClosure::do_oop_work(p); } |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6587 |
0 | 6588 void MarkRefsIntoAndScanClosure::do_yield_work() { |
6589 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
6590 "CMS thread should hold CMS token"); | |
6591 assert_lock_strong(_freelistLock); | |
6592 assert_lock_strong(_bit_map->lock()); | |
6593 // relinquish the free_list_lock and bitMaplock() | |
935 | 6594 DEBUG_ONLY(RememberKlassesChecker mux(false);) |
0 | 6595 _bit_map->lock()->unlock(); |
6596 _freelistLock->unlock(); | |
6597 ConcurrentMarkSweepThread::desynchronize(true); | |
6598 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
6599 _collector->stopTimer(); | |
6600 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
6601 if (PrintCMSStatistics != 0) { | |
6602 _collector->incrementYields(); | |
6603 } | |
6604 _collector->icms_wait(); | |
6605 | |
6606 // See the comment in coordinator_yield() | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6607 for (unsigned i = 0; |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6608 i < CMSYieldSleepCount && |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6609 ConcurrentMarkSweepThread::should_yield() && |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6610 !CMSCollector::foregroundGCIsActive(); |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6611 ++i) { |
0 | 6612 os::sleep(Thread::current(), 1, false); |
6613 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
6614 } | |
6615 | |
6616 ConcurrentMarkSweepThread::synchronize(true); | |
6617 _freelistLock->lock_without_safepoint_check(); | |
6618 _bit_map->lock()->lock_without_safepoint_check(); | |
6619 _collector->startTimer(); | |
6620 } | |
6621 | |
6622 /////////////////////////////////////////////////////////// | |
6623 // Par_MarkRefsIntoAndScanClosure: a parallel version of | |
6624 // MarkRefsIntoAndScanClosure | |
6625 /////////////////////////////////////////////////////////// | |
6626 Par_MarkRefsIntoAndScanClosure::Par_MarkRefsIntoAndScanClosure( | |
6627 CMSCollector* collector, MemRegion span, ReferenceProcessor* rp, | |
6628 CMSBitMap* bit_map, OopTaskQueue* work_queue, CMSMarkStack* revisit_stack): | |
6629 _span(span), | |
6630 _bit_map(bit_map), | |
6631 _work_queue(work_queue), | |
6632 _low_water_mark(MIN2((uint)(work_queue->max_elems()/4), | |
6633 (uint)(CMSWorkQueueDrainThreshold * ParallelGCThreads))), | |
6634 _par_pushAndMarkClosure(collector, span, rp, bit_map, work_queue, | |
6635 revisit_stack) | |
6636 { | |
6637 _ref_processor = rp; | |
6638 assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL"); | |
6639 } | |
6640 | |
6641 // This closure is used to mark refs into the CMS generation at the | |
6642 // second (final) checkpoint, and to scan and transitively follow | |
6643 // the unmarked oops. The marks are made in the marking bit map and | |
6644 // the work_queue is used for keeping the (newly) grey objects during | |
6645 // the scan phase whence they are also available for stealing by parallel | |
6646 // threads. Since the marking bit map is shared, updates are | |
6647 // synchronized (via CAS). | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6648 void Par_MarkRefsIntoAndScanClosure::do_oop(oop obj) { |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6649 if (obj != NULL) { |
0 | 6650 // Ignore mark word because this could be an already marked oop |
6651 // that may be chained at the end of the overflow list. | |
340
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
6652 assert(obj->is_oop(true), "expected an oop"); |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6653 HeapWord* addr = (HeapWord*)obj; |
0 | 6654 if (_span.contains(addr) && |
6655 !_bit_map->isMarked(addr)) { | |
6656 // mark bit map (object will become grey): | |
6657 // It is possible for several threads to be | |
6658 // trying to "claim" this object concurrently; | |
6659 // the unique thread that succeeds in marking the | |
6660 // object first will do the subsequent push on | |
6661 // to the work queue (or overflow list). | |
6662 if (_bit_map->par_mark(addr)) { | |
6663 // push on work_queue (which may not be empty), and trim the | |
6664 // queue to an appropriate length by applying this closure to | |
6665 // the oops in the oops popped from the stack (i.e. blacken the | |
6666 // grey objects) | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6667 bool res = _work_queue->push(obj); |
0 | 6668 assert(res, "Low water mark should be less than capacity?"); |
6669 trim_queue(_low_water_mark); | |
6670 } // Else, another thread claimed the object | |
6671 } | |
6672 } | |
6673 } | |
6674 | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6675 void Par_MarkRefsIntoAndScanClosure::do_oop(oop* p) { Par_MarkRefsIntoAndScanClosure::do_oop_work(p); } |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6676 void Par_MarkRefsIntoAndScanClosure::do_oop(narrowOop* p) { Par_MarkRefsIntoAndScanClosure::do_oop_work(p); } |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6677 |
0 | 6678 // This closure is used to rescan the marked objects on the dirty cards |
6679 // in the mod union table and the card table proper. | |
6680 size_t ScanMarkedObjectsAgainCarefullyClosure::do_object_careful_m( | |
6681 oop p, MemRegion mr) { | |
6682 | |
6683 size_t size = 0; | |
6684 HeapWord* addr = (HeapWord*)p; | |
6685 DEBUG_ONLY(_collector->verify_work_stacks_empty();) | |
6686 assert(_span.contains(addr), "we are scanning the CMS generation"); | |
6687 // check if it's time to yield | |
6688 if (do_yield_check()) { | |
6689 // We yielded for some foreground stop-world work, | |
6690 // and we have been asked to abort this ongoing preclean cycle. | |
6691 return 0; | |
6692 } | |
6693 if (_bitMap->isMarked(addr)) { | |
6694 // it's marked; is it potentially uninitialized? | |
187 | 6695 if (p->klass_or_null() != NULL) { |
518
0af8b0718fc9
6692899: CMS: many vm.parallel_class_loading tests fail with assert "missing Printezis mark"
jmasa
parents:
517
diff
changeset
|
6696 // If is_conc_safe is false, the object may be undergoing |
0af8b0718fc9
6692899: CMS: many vm.parallel_class_loading tests fail with assert "missing Printezis mark"
jmasa
parents:
517
diff
changeset
|
6697 // change by the VM outside a safepoint. Don't try to |
0af8b0718fc9
6692899: CMS: many vm.parallel_class_loading tests fail with assert "missing Printezis mark"
jmasa
parents:
517
diff
changeset
|
6698 // scan it, but rather leave it for the remark phase. |
0af8b0718fc9
6692899: CMS: many vm.parallel_class_loading tests fail with assert "missing Printezis mark"
jmasa
parents:
517
diff
changeset
|
6699 if (CMSPermGenPrecleaningEnabled && |
0af8b0718fc9
6692899: CMS: many vm.parallel_class_loading tests fail with assert "missing Printezis mark"
jmasa
parents:
517
diff
changeset
|
6700 (!p->is_conc_safe() || !p->is_parsable())) { |
0 | 6701 // Signal precleaning to redirty the card since |
6702 // the klass pointer is already installed. | |
6703 assert(size == 0, "Initial value"); | |
6704 } else { | |
6705 assert(p->is_parsable(), "must be parsable."); | |
6706 // an initialized object; ignore mark word in verification below | |
6707 // since we are running concurrent with mutators | |
6708 assert(p->is_oop(true), "should be an oop"); | |
6709 if (p->is_objArray()) { | |
6710 // objArrays are precisely marked; restrict scanning | |
6711 // to dirty cards only. | |
187 | 6712 size = CompactibleFreeListSpace::adjustObjectSize( |
6713 p->oop_iterate(_scanningClosure, mr)); | |
0 | 6714 } else { |
6715 // A non-array may have been imprecisely marked; we need | |
6716 // to scan object in its entirety. | |
6717 size = CompactibleFreeListSpace::adjustObjectSize( | |
6718 p->oop_iterate(_scanningClosure)); | |
6719 } | |
6720 #ifdef DEBUG | |
6721 size_t direct_size = | |
6722 CompactibleFreeListSpace::adjustObjectSize(p->size()); | |
6723 assert(size == direct_size, "Inconsistency in size"); | |
6724 assert(size >= 3, "Necessary for Printezis marks to work"); | |
6725 if (!_bitMap->isMarked(addr+1)) { | |
6726 _bitMap->verifyNoOneBitsInRange(addr+2, addr+size); | |
6727 } else { | |
6728 _bitMap->verifyNoOneBitsInRange(addr+2, addr+size-1); | |
6729 assert(_bitMap->isMarked(addr+size-1), | |
6730 "inconsistent Printezis mark"); | |
6731 } | |
6732 #endif // DEBUG | |
6733 } | |
6734 } else { | |
6735 // an unitialized object | |
6736 assert(_bitMap->isMarked(addr+1), "missing Printezis mark?"); | |
6737 HeapWord* nextOneAddr = _bitMap->getNextMarkedWordAddress(addr + 2); | |
6738 size = pointer_delta(nextOneAddr + 1, addr); | |
6739 assert(size == CompactibleFreeListSpace::adjustObjectSize(size), | |
6740 "alignment problem"); | |
6741 // Note that pre-cleaning needn't redirty the card. OopDesc::set_klass() | |
6742 // will dirty the card when the klass pointer is installed in the | |
6743 // object (signalling the completion of initialization). | |
6744 } | |
6745 } else { | |
6746 // Either a not yet marked object or an uninitialized object | |
187 | 6747 if (p->klass_or_null() == NULL || !p->is_parsable()) { |
0 | 6748 // An uninitialized object, skip to the next card, since |
6749 // we may not be able to read its P-bits yet. | |
6750 assert(size == 0, "Initial value"); | |
6751 } else { | |
6752 // An object not (yet) reached by marking: we merely need to | |
6753 // compute its size so as to go look at the next block. | |
6754 assert(p->is_oop(true), "should be an oop"); | |
6755 size = CompactibleFreeListSpace::adjustObjectSize(p->size()); | |
6756 } | |
6757 } | |
6758 DEBUG_ONLY(_collector->verify_work_stacks_empty();) | |
6759 return size; | |
6760 } | |
6761 | |
6762 void ScanMarkedObjectsAgainCarefullyClosure::do_yield_work() { | |
6763 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
6764 "CMS thread should hold CMS token"); | |
6765 assert_lock_strong(_freelistLock); | |
6766 assert_lock_strong(_bitMap->lock()); | |
935 | 6767 DEBUG_ONLY(RememberKlassesChecker mux(false);) |
0 | 6768 // relinquish the free_list_lock and bitMaplock() |
6769 _bitMap->lock()->unlock(); | |
6770 _freelistLock->unlock(); | |
6771 ConcurrentMarkSweepThread::desynchronize(true); | |
6772 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
6773 _collector->stopTimer(); | |
6774 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
6775 if (PrintCMSStatistics != 0) { | |
6776 _collector->incrementYields(); | |
6777 } | |
6778 _collector->icms_wait(); | |
6779 | |
6780 // See the comment in coordinator_yield() | |
6781 for (unsigned i = 0; i < CMSYieldSleepCount && | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6782 ConcurrentMarkSweepThread::should_yield() && |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
6783 !CMSCollector::foregroundGCIsActive(); ++i) { |
0 | 6784 os::sleep(Thread::current(), 1, false); |
6785 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
6786 } | |
6787 | |
6788 ConcurrentMarkSweepThread::synchronize(true); | |
6789 _freelistLock->lock_without_safepoint_check(); | |
6790 _bitMap->lock()->lock_without_safepoint_check(); | |
6791 _collector->startTimer(); | |
6792 } | |
6793 | |
6794 | |
6795 ////////////////////////////////////////////////////////////////// | |
6796 // SurvivorSpacePrecleanClosure | |
6797 ////////////////////////////////////////////////////////////////// | |
6798 // This (single-threaded) closure is used to preclean the oops in | |
6799 // the survivor spaces. | |
6800 size_t SurvivorSpacePrecleanClosure::do_object_careful(oop p) { | |
6801 | |
6802 HeapWord* addr = (HeapWord*)p; | |
6803 DEBUG_ONLY(_collector->verify_work_stacks_empty();) | |
6804 assert(!_span.contains(addr), "we are scanning the survivor spaces"); | |
187 | 6805 assert(p->klass_or_null() != NULL, "object should be initializd"); |
0 | 6806 assert(p->is_parsable(), "must be parsable."); |
6807 // an initialized object; ignore mark word in verification below | |
6808 // since we are running concurrent with mutators | |
6809 assert(p->is_oop(true), "should be an oop"); | |
6810 // Note that we do not yield while we iterate over | |
6811 // the interior oops of p, pushing the relevant ones | |
6812 // on our marking stack. | |
6813 size_t size = p->oop_iterate(_scanning_closure); | |
6814 do_yield_check(); | |
6815 // Observe that below, we do not abandon the preclean | |
6816 // phase as soon as we should; rather we empty the | |
6817 // marking stack before returning. This is to satisfy | |
6818 // some existing assertions. In general, it may be a | |
6819 // good idea to abort immediately and complete the marking | |
6820 // from the grey objects at a later time. | |
6821 while (!_mark_stack->isEmpty()) { | |
6822 oop new_oop = _mark_stack->pop(); | |
6823 assert(new_oop != NULL && new_oop->is_oop(), "Expected an oop"); | |
6824 assert(new_oop->is_parsable(), "Found unparsable oop"); | |
6825 assert(_bit_map->isMarked((HeapWord*)new_oop), | |
6826 "only grey objects on this stack"); | |
6827 // iterate over the oops in this oop, marking and pushing | |
6828 // the ones in CMS heap (i.e. in _span). | |
6829 new_oop->oop_iterate(_scanning_closure); | |
6830 // check if it's time to yield | |
6831 do_yield_check(); | |
6832 } | |
6833 unsigned int after_count = | |
6834 GenCollectedHeap::heap()->total_collections(); | |
6835 bool abort = (_before_count != after_count) || | |
6836 _collector->should_abort_preclean(); | |
6837 return abort ? 0 : size; | |
6838 } | |
6839 | |
6840 void SurvivorSpacePrecleanClosure::do_yield_work() { | |
6841 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
6842 "CMS thread should hold CMS token"); | |
6843 assert_lock_strong(_bit_map->lock()); | |
935 | 6844 DEBUG_ONLY(RememberKlassesChecker smx(false);) |
0 | 6845 // Relinquish the bit map lock |
6846 _bit_map->lock()->unlock(); | |
6847 ConcurrentMarkSweepThread::desynchronize(true); | |
6848 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
6849 _collector->stopTimer(); | |
6850 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
6851 if (PrintCMSStatistics != 0) { | |
6852 _collector->incrementYields(); | |
6853 } | |
6854 _collector->icms_wait(); | |
6855 | |
6856 // See the comment in coordinator_yield() | |
6857 for (unsigned i = 0; i < CMSYieldSleepCount && | |
6858 ConcurrentMarkSweepThread::should_yield() && | |
6859 !CMSCollector::foregroundGCIsActive(); ++i) { | |
6860 os::sleep(Thread::current(), 1, false); | |
6861 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
6862 } | |
6863 | |
6864 ConcurrentMarkSweepThread::synchronize(true); | |
6865 _bit_map->lock()->lock_without_safepoint_check(); | |
6866 _collector->startTimer(); | |
6867 } | |
6868 | |
6869 // This closure is used to rescan the marked objects on the dirty cards | |
6870 // in the mod union table and the card table proper. In the parallel | |
6871 // case, although the bitMap is shared, we do a single read so the | |
6872 // isMarked() query is "safe". | |
6873 bool ScanMarkedObjectsAgainClosure::do_object_bm(oop p, MemRegion mr) { | |
6874 // Ignore mark word because we are running concurrent with mutators | |
6875 assert(p->is_oop_or_null(true), "expected an oop or null"); | |
6876 HeapWord* addr = (HeapWord*)p; | |
6877 assert(_span.contains(addr), "we are scanning the CMS generation"); | |
6878 bool is_obj_array = false; | |
6879 #ifdef DEBUG | |
6880 if (!_parallel) { | |
6881 assert(_mark_stack->isEmpty(), "pre-condition (eager drainage)"); | |
6882 assert(_collector->overflow_list_is_empty(), | |
6883 "overflow list should be empty"); | |
6884 | |
6885 } | |
6886 #endif // DEBUG | |
6887 if (_bit_map->isMarked(addr)) { | |
6888 // Obj arrays are precisely marked, non-arrays are not; | |
6889 // so we scan objArrays precisely and non-arrays in their | |
6890 // entirety. | |
6891 if (p->is_objArray()) { | |
6892 is_obj_array = true; | |
6893 if (_parallel) { | |
6894 p->oop_iterate(_par_scan_closure, mr); | |
6895 } else { | |
6896 p->oop_iterate(_scan_closure, mr); | |
6897 } | |
6898 } else { | |
6899 if (_parallel) { | |
6900 p->oop_iterate(_par_scan_closure); | |
6901 } else { | |
6902 p->oop_iterate(_scan_closure); | |
6903 } | |
6904 } | |
6905 } | |
6906 #ifdef DEBUG | |
6907 if (!_parallel) { | |
6908 assert(_mark_stack->isEmpty(), "post-condition (eager drainage)"); | |
6909 assert(_collector->overflow_list_is_empty(), | |
6910 "overflow list should be empty"); | |
6911 | |
6912 } | |
6913 #endif // DEBUG | |
6914 return is_obj_array; | |
6915 } | |
6916 | |
6917 MarkFromRootsClosure::MarkFromRootsClosure(CMSCollector* collector, | |
6918 MemRegion span, | |
6919 CMSBitMap* bitMap, CMSMarkStack* markStack, | |
6920 CMSMarkStack* revisitStack, | |
6921 bool should_yield, bool verifying): | |
6922 _collector(collector), | |
6923 _span(span), | |
6924 _bitMap(bitMap), | |
6925 _mut(&collector->_modUnionTable), | |
6926 _markStack(markStack), | |
6927 _revisitStack(revisitStack), | |
6928 _yield(should_yield), | |
6929 _skipBits(0) | |
6930 { | |
6931 assert(_markStack->isEmpty(), "stack should be empty"); | |
6932 _finger = _bitMap->startWord(); | |
6933 _threshold = _finger; | |
6934 assert(_collector->_restart_addr == NULL, "Sanity check"); | |
6935 assert(_span.contains(_finger), "Out of bounds _finger?"); | |
6936 DEBUG_ONLY(_verifying = verifying;) | |
6937 } | |
6938 | |
6939 void MarkFromRootsClosure::reset(HeapWord* addr) { | |
6940 assert(_markStack->isEmpty(), "would cause duplicates on stack"); | |
6941 assert(_span.contains(addr), "Out of bounds _finger?"); | |
6942 _finger = addr; | |
6943 _threshold = (HeapWord*)round_to( | |
6944 (intptr_t)_finger, CardTableModRefBS::card_size); | |
6945 } | |
6946 | |
6947 // Should revisit to see if this should be restructured for | |
6948 // greater efficiency. | |
342
37f87013dfd8
6711316: Open source the Garbage-First garbage collector
ysr
parents:
143
diff
changeset
|
6949 bool MarkFromRootsClosure::do_bit(size_t offset) { |
0 | 6950 if (_skipBits > 0) { |
6951 _skipBits--; | |
342
37f87013dfd8
6711316: Open source the Garbage-First garbage collector
ysr
parents:
143
diff
changeset
|
6952 return true; |
0 | 6953 } |
6954 // convert offset into a HeapWord* | |
6955 HeapWord* addr = _bitMap->startWord() + offset; | |
6956 assert(_bitMap->endWord() && addr < _bitMap->endWord(), | |
6957 "address out of range"); | |
6958 assert(_bitMap->isMarked(addr), "tautology"); | |
6959 if (_bitMap->isMarked(addr+1)) { | |
6960 // this is an allocated but not yet initialized object | |
6961 assert(_skipBits == 0, "tautology"); | |
6962 _skipBits = 2; // skip next two marked bits ("Printezis-marks") | |
6963 oop p = oop(addr); | |
187 | 6964 if (p->klass_or_null() == NULL || !p->is_parsable()) { |
0 | 6965 DEBUG_ONLY(if (!_verifying) {) |
6966 // We re-dirty the cards on which this object lies and increase | |
6967 // the _threshold so that we'll come back to scan this object | |
6968 // during the preclean or remark phase. (CMSCleanOnEnter) | |
6969 if (CMSCleanOnEnter) { | |
6970 size_t sz = _collector->block_size_using_printezis_bits(addr); | |
6971 HeapWord* end_card_addr = (HeapWord*)round_to( | |
6972 (intptr_t)(addr+sz), CardTableModRefBS::card_size); | |
283
9199f248b0ee
6722112: CMS: Incorrect encoding of overflown object arrays during concurrent precleaning
ysr
parents:
271
diff
changeset
|
6973 MemRegion redirty_range = MemRegion(addr, end_card_addr); |
0 | 6974 assert(!redirty_range.is_empty(), "Arithmetical tautology"); |
6975 // Bump _threshold to end_card_addr; note that | |
6976 // _threshold cannot possibly exceed end_card_addr, anyhow. | |
6977 // This prevents future clearing of the card as the scan proceeds | |
6978 // to the right. | |
6979 assert(_threshold <= end_card_addr, | |
6980 "Because we are just scanning into this object"); | |
6981 if (_threshold < end_card_addr) { | |
6982 _threshold = end_card_addr; | |
6983 } | |
187 | 6984 if (p->klass_or_null() != NULL) { |
0 | 6985 // Redirty the range of cards... |
6986 _mut->mark_range(redirty_range); | |
6987 } // ...else the setting of klass will dirty the card anyway. | |
6988 } | |
6989 DEBUG_ONLY(}) | |
342
37f87013dfd8
6711316: Open source the Garbage-First garbage collector
ysr
parents:
143
diff
changeset
|
6990 return true; |
0 | 6991 } |
6992 } | |
6993 scanOopsInOop(addr); | |
342
37f87013dfd8
6711316: Open source the Garbage-First garbage collector
ysr
parents:
143
diff
changeset
|
6994 return true; |
0 | 6995 } |
6996 | |
6997 // We take a break if we've been at this for a while, | |
6998 // so as to avoid monopolizing the locks involved. | |
6999 void MarkFromRootsClosure::do_yield_work() { | |
7000 // First give up the locks, then yield, then re-lock | |
7001 // We should probably use a constructor/destructor idiom to | |
7002 // do this unlock/lock or modify the MutexUnlocker class to | |
7003 // serve our purpose. XXX | |
7004 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
7005 "CMS thread should hold CMS token"); | |
7006 assert_lock_strong(_bitMap->lock()); | |
935 | 7007 DEBUG_ONLY(RememberKlassesChecker mux(false);) |
0 | 7008 _bitMap->lock()->unlock(); |
7009 ConcurrentMarkSweepThread::desynchronize(true); | |
7010 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
7011 _collector->stopTimer(); | |
7012 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
7013 if (PrintCMSStatistics != 0) { | |
7014 _collector->incrementYields(); | |
7015 } | |
7016 _collector->icms_wait(); | |
7017 | |
7018 // See the comment in coordinator_yield() | |
7019 for (unsigned i = 0; i < CMSYieldSleepCount && | |
7020 ConcurrentMarkSweepThread::should_yield() && | |
7021 !CMSCollector::foregroundGCIsActive(); ++i) { | |
7022 os::sleep(Thread::current(), 1, false); | |
7023 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
7024 } | |
7025 | |
7026 ConcurrentMarkSweepThread::synchronize(true); | |
7027 _bitMap->lock()->lock_without_safepoint_check(); | |
7028 _collector->startTimer(); | |
7029 } | |
7030 | |
7031 void MarkFromRootsClosure::scanOopsInOop(HeapWord* ptr) { | |
7032 assert(_bitMap->isMarked(ptr), "expected bit to be set"); | |
7033 assert(_markStack->isEmpty(), | |
7034 "should drain stack to limit stack usage"); | |
7035 // convert ptr to an oop preparatory to scanning | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7036 oop obj = oop(ptr); |
0 | 7037 // Ignore mark word in verification below, since we |
7038 // may be running concurrent with mutators. | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7039 assert(obj->is_oop(true), "should be an oop"); |
0 | 7040 assert(_finger <= ptr, "_finger runneth ahead"); |
7041 // advance the finger to right end of this object | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7042 _finger = ptr + obj->size(); |
0 | 7043 assert(_finger > ptr, "we just incremented it above"); |
7044 // On large heaps, it may take us some time to get through | |
7045 // the marking phase (especially if running iCMS). During | |
7046 // this time it's possible that a lot of mutations have | |
7047 // accumulated in the card table and the mod union table -- | |
7048 // these mutation records are redundant until we have | |
7049 // actually traced into the corresponding card. | |
7050 // Here, we check whether advancing the finger would make | |
7051 // us cross into a new card, and if so clear corresponding | |
7052 // cards in the MUT (preclean them in the card-table in the | |
7053 // future). | |
7054 | |
7055 DEBUG_ONLY(if (!_verifying) {) | |
7056 // The clean-on-enter optimization is disabled by default, | |
7057 // until we fix 6178663. | |
7058 if (CMSCleanOnEnter && (_finger > _threshold)) { | |
7059 // [_threshold, _finger) represents the interval | |
7060 // of cards to be cleared in MUT (or precleaned in card table). | |
7061 // The set of cards to be cleared is all those that overlap | |
7062 // with the interval [_threshold, _finger); note that | |
7063 // _threshold is always kept card-aligned but _finger isn't | |
7064 // always card-aligned. | |
7065 HeapWord* old_threshold = _threshold; | |
7066 assert(old_threshold == (HeapWord*)round_to( | |
7067 (intptr_t)old_threshold, CardTableModRefBS::card_size), | |
7068 "_threshold should always be card-aligned"); | |
7069 _threshold = (HeapWord*)round_to( | |
7070 (intptr_t)_finger, CardTableModRefBS::card_size); | |
7071 MemRegion mr(old_threshold, _threshold); | |
7072 assert(!mr.is_empty(), "Control point invariant"); | |
7073 assert(_span.contains(mr), "Should clear within span"); | |
7074 // XXX When _finger crosses from old gen into perm gen | |
7075 // we may be doing unnecessary cleaning; do better in the | |
7076 // future by detecting that condition and clearing fewer | |
7077 // MUT/CT entries. | |
7078 _mut->clear_range(mr); | |
7079 } | |
7080 DEBUG_ONLY(}) | |
7081 // Note: the finger doesn't advance while we drain | |
7082 // the stack below. | |
7083 PushOrMarkClosure pushOrMarkClosure(_collector, | |
7084 _span, _bitMap, _markStack, | |
7085 _revisitStack, | |
7086 _finger, this); | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7087 bool res = _markStack->push(obj); |
0 | 7088 assert(res, "Empty non-zero size stack should have space for single push"); |
7089 while (!_markStack->isEmpty()) { | |
7090 oop new_oop = _markStack->pop(); | |
7091 // Skip verifying header mark word below because we are | |
7092 // running concurrent with mutators. | |
7093 assert(new_oop->is_oop(true), "Oops! expected to pop an oop"); | |
7094 // now scan this oop's oops | |
7095 new_oop->oop_iterate(&pushOrMarkClosure); | |
7096 do_yield_check(); | |
7097 } | |
7098 assert(_markStack->isEmpty(), "tautology, emphasizing post-condition"); | |
7099 } | |
7100 | |
7101 Par_MarkFromRootsClosure::Par_MarkFromRootsClosure(CMSConcMarkingTask* task, | |
7102 CMSCollector* collector, MemRegion span, | |
7103 CMSBitMap* bit_map, | |
7104 OopTaskQueue* work_queue, | |
7105 CMSMarkStack* overflow_stack, | |
7106 CMSMarkStack* revisit_stack, | |
7107 bool should_yield): | |
7108 _collector(collector), | |
7109 _whole_span(collector->_span), | |
7110 _span(span), | |
7111 _bit_map(bit_map), | |
7112 _mut(&collector->_modUnionTable), | |
7113 _work_queue(work_queue), | |
7114 _overflow_stack(overflow_stack), | |
7115 _revisit_stack(revisit_stack), | |
7116 _yield(should_yield), | |
7117 _skip_bits(0), | |
7118 _task(task) | |
7119 { | |
7120 assert(_work_queue->size() == 0, "work_queue should be empty"); | |
7121 _finger = span.start(); | |
7122 _threshold = _finger; // XXX Defer clear-on-enter optimization for now | |
7123 assert(_span.contains(_finger), "Out of bounds _finger?"); | |
7124 } | |
7125 | |
7126 // Should revisit to see if this should be restructured for | |
7127 // greater efficiency. | |
342
37f87013dfd8
6711316: Open source the Garbage-First garbage collector
ysr
parents:
143
diff
changeset
|
7128 bool Par_MarkFromRootsClosure::do_bit(size_t offset) { |
0 | 7129 if (_skip_bits > 0) { |
7130 _skip_bits--; | |
342
37f87013dfd8
6711316: Open source the Garbage-First garbage collector
ysr
parents:
143
diff
changeset
|
7131 return true; |
0 | 7132 } |
7133 // convert offset into a HeapWord* | |
7134 HeapWord* addr = _bit_map->startWord() + offset; | |
7135 assert(_bit_map->endWord() && addr < _bit_map->endWord(), | |
7136 "address out of range"); | |
7137 assert(_bit_map->isMarked(addr), "tautology"); | |
7138 if (_bit_map->isMarked(addr+1)) { | |
7139 // this is an allocated object that might not yet be initialized | |
7140 assert(_skip_bits == 0, "tautology"); | |
7141 _skip_bits = 2; // skip next two marked bits ("Printezis-marks") | |
7142 oop p = oop(addr); | |
187 | 7143 if (p->klass_or_null() == NULL || !p->is_parsable()) { |
0 | 7144 // in the case of Clean-on-Enter optimization, redirty card |
7145 // and avoid clearing card by increasing the threshold. | |
342
37f87013dfd8
6711316: Open source the Garbage-First garbage collector
ysr
parents:
143
diff
changeset
|
7146 return true; |
0 | 7147 } |
7148 } | |
7149 scan_oops_in_oop(addr); | |
342
37f87013dfd8
6711316: Open source the Garbage-First garbage collector
ysr
parents:
143
diff
changeset
|
7150 return true; |
0 | 7151 } |
7152 | |
7153 void Par_MarkFromRootsClosure::scan_oops_in_oop(HeapWord* ptr) { | |
7154 assert(_bit_map->isMarked(ptr), "expected bit to be set"); | |
7155 // Should we assert that our work queue is empty or | |
7156 // below some drain limit? | |
7157 assert(_work_queue->size() == 0, | |
7158 "should drain stack to limit stack usage"); | |
7159 // convert ptr to an oop preparatory to scanning | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7160 oop obj = oop(ptr); |
0 | 7161 // Ignore mark word in verification below, since we |
7162 // may be running concurrent with mutators. | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7163 assert(obj->is_oop(true), "should be an oop"); |
0 | 7164 assert(_finger <= ptr, "_finger runneth ahead"); |
7165 // advance the finger to right end of this object | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7166 _finger = ptr + obj->size(); |
0 | 7167 assert(_finger > ptr, "we just incremented it above"); |
7168 // On large heaps, it may take us some time to get through | |
7169 // the marking phase (especially if running iCMS). During | |
7170 // this time it's possible that a lot of mutations have | |
7171 // accumulated in the card table and the mod union table -- | |
7172 // these mutation records are redundant until we have | |
7173 // actually traced into the corresponding card. | |
7174 // Here, we check whether advancing the finger would make | |
7175 // us cross into a new card, and if so clear corresponding | |
7176 // cards in the MUT (preclean them in the card-table in the | |
7177 // future). | |
7178 | |
7179 // The clean-on-enter optimization is disabled by default, | |
7180 // until we fix 6178663. | |
7181 if (CMSCleanOnEnter && (_finger > _threshold)) { | |
7182 // [_threshold, _finger) represents the interval | |
7183 // of cards to be cleared in MUT (or precleaned in card table). | |
7184 // The set of cards to be cleared is all those that overlap | |
7185 // with the interval [_threshold, _finger); note that | |
7186 // _threshold is always kept card-aligned but _finger isn't | |
7187 // always card-aligned. | |
7188 HeapWord* old_threshold = _threshold; | |
7189 assert(old_threshold == (HeapWord*)round_to( | |
7190 (intptr_t)old_threshold, CardTableModRefBS::card_size), | |
7191 "_threshold should always be card-aligned"); | |
7192 _threshold = (HeapWord*)round_to( | |
7193 (intptr_t)_finger, CardTableModRefBS::card_size); | |
7194 MemRegion mr(old_threshold, _threshold); | |
7195 assert(!mr.is_empty(), "Control point invariant"); | |
7196 assert(_span.contains(mr), "Should clear within span"); // _whole_span ?? | |
7197 // XXX When _finger crosses from old gen into perm gen | |
7198 // we may be doing unnecessary cleaning; do better in the | |
7199 // future by detecting that condition and clearing fewer | |
7200 // MUT/CT entries. | |
7201 _mut->clear_range(mr); | |
7202 } | |
7203 | |
7204 // Note: the local finger doesn't advance while we drain | |
7205 // the stack below, but the global finger sure can and will. | |
7206 HeapWord** gfa = _task->global_finger_addr(); | |
7207 Par_PushOrMarkClosure pushOrMarkClosure(_collector, | |
7208 _span, _bit_map, | |
7209 _work_queue, | |
7210 _overflow_stack, | |
7211 _revisit_stack, | |
7212 _finger, | |
7213 gfa, this); | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7214 bool res = _work_queue->push(obj); // overflow could occur here |
0 | 7215 assert(res, "Will hold once we use workqueues"); |
7216 while (true) { | |
7217 oop new_oop; | |
7218 if (!_work_queue->pop_local(new_oop)) { | |
7219 // We emptied our work_queue; check if there's stuff that can | |
7220 // be gotten from the overflow stack. | |
7221 if (CMSConcMarkingTask::get_work_from_overflow_stack( | |
7222 _overflow_stack, _work_queue)) { | |
7223 do_yield_check(); | |
7224 continue; | |
7225 } else { // done | |
7226 break; | |
7227 } | |
7228 } | |
7229 // Skip verifying header mark word below because we are | |
7230 // running concurrent with mutators. | |
7231 assert(new_oop->is_oop(true), "Oops! expected to pop an oop"); | |
7232 // now scan this oop's oops | |
7233 new_oop->oop_iterate(&pushOrMarkClosure); | |
7234 do_yield_check(); | |
7235 } | |
7236 assert(_work_queue->size() == 0, "tautology, emphasizing post-condition"); | |
7237 } | |
7238 | |
7239 // Yield in response to a request from VM Thread or | |
7240 // from mutators. | |
7241 void Par_MarkFromRootsClosure::do_yield_work() { | |
7242 assert(_task != NULL, "sanity"); | |
7243 _task->yield(); | |
7244 } | |
7245 | |
7246 // A variant of the above used for verifying CMS marking work. | |
7247 MarkFromRootsVerifyClosure::MarkFromRootsVerifyClosure(CMSCollector* collector, | |
7248 MemRegion span, | |
7249 CMSBitMap* verification_bm, CMSBitMap* cms_bm, | |
7250 CMSMarkStack* mark_stack): | |
7251 _collector(collector), | |
7252 _span(span), | |
7253 _verification_bm(verification_bm), | |
7254 _cms_bm(cms_bm), | |
7255 _mark_stack(mark_stack), | |
7256 _pam_verify_closure(collector, span, verification_bm, cms_bm, | |
7257 mark_stack) | |
7258 { | |
7259 assert(_mark_stack->isEmpty(), "stack should be empty"); | |
7260 _finger = _verification_bm->startWord(); | |
7261 assert(_collector->_restart_addr == NULL, "Sanity check"); | |
7262 assert(_span.contains(_finger), "Out of bounds _finger?"); | |
7263 } | |
7264 | |
7265 void MarkFromRootsVerifyClosure::reset(HeapWord* addr) { | |
7266 assert(_mark_stack->isEmpty(), "would cause duplicates on stack"); | |
7267 assert(_span.contains(addr), "Out of bounds _finger?"); | |
7268 _finger = addr; | |
7269 } | |
7270 | |
7271 // Should revisit to see if this should be restructured for | |
7272 // greater efficiency. | |
342
37f87013dfd8
6711316: Open source the Garbage-First garbage collector
ysr
parents:
143
diff
changeset
|
7273 bool MarkFromRootsVerifyClosure::do_bit(size_t offset) { |
0 | 7274 // convert offset into a HeapWord* |
7275 HeapWord* addr = _verification_bm->startWord() + offset; | |
7276 assert(_verification_bm->endWord() && addr < _verification_bm->endWord(), | |
7277 "address out of range"); | |
7278 assert(_verification_bm->isMarked(addr), "tautology"); | |
7279 assert(_cms_bm->isMarked(addr), "tautology"); | |
7280 | |
7281 assert(_mark_stack->isEmpty(), | |
7282 "should drain stack to limit stack usage"); | |
7283 // convert addr to an oop preparatory to scanning | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7284 oop obj = oop(addr); |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7285 assert(obj->is_oop(), "should be an oop"); |
0 | 7286 assert(_finger <= addr, "_finger runneth ahead"); |
7287 // advance the finger to right end of this object | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7288 _finger = addr + obj->size(); |
0 | 7289 assert(_finger > addr, "we just incremented it above"); |
7290 // Note: the finger doesn't advance while we drain | |
7291 // the stack below. | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7292 bool res = _mark_stack->push(obj); |
0 | 7293 assert(res, "Empty non-zero size stack should have space for single push"); |
7294 while (!_mark_stack->isEmpty()) { | |
7295 oop new_oop = _mark_stack->pop(); | |
7296 assert(new_oop->is_oop(), "Oops! expected to pop an oop"); | |
7297 // now scan this oop's oops | |
7298 new_oop->oop_iterate(&_pam_verify_closure); | |
7299 } | |
7300 assert(_mark_stack->isEmpty(), "tautology, emphasizing post-condition"); | |
342
37f87013dfd8
6711316: Open source the Garbage-First garbage collector
ysr
parents:
143
diff
changeset
|
7301 return true; |
0 | 7302 } |
7303 | |
7304 PushAndMarkVerifyClosure::PushAndMarkVerifyClosure( | |
7305 CMSCollector* collector, MemRegion span, | |
7306 CMSBitMap* verification_bm, CMSBitMap* cms_bm, | |
7307 CMSMarkStack* mark_stack): | |
7308 OopClosure(collector->ref_processor()), | |
7309 _collector(collector), | |
7310 _span(span), | |
7311 _verification_bm(verification_bm), | |
7312 _cms_bm(cms_bm), | |
7313 _mark_stack(mark_stack) | |
7314 { } | |
7315 | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7316 void PushAndMarkVerifyClosure::do_oop(oop* p) { PushAndMarkVerifyClosure::do_oop_work(p); } |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7317 void PushAndMarkVerifyClosure::do_oop(narrowOop* p) { PushAndMarkVerifyClosure::do_oop_work(p); } |
0 | 7318 |
7319 // Upon stack overflow, we discard (part of) the stack, | |
7320 // remembering the least address amongst those discarded | |
7321 // in CMSCollector's _restart_address. | |
7322 void PushAndMarkVerifyClosure::handle_stack_overflow(HeapWord* lost) { | |
7323 // Remember the least grey address discarded | |
7324 HeapWord* ra = (HeapWord*)_mark_stack->least_value(lost); | |
7325 _collector->lower_restart_addr(ra); | |
7326 _mark_stack->reset(); // discard stack contents | |
7327 _mark_stack->expand(); // expand the stack if possible | |
7328 } | |
7329 | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7330 void PushAndMarkVerifyClosure::do_oop(oop obj) { |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7331 assert(obj->is_oop_or_null(), "expected an oop or NULL"); |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7332 HeapWord* addr = (HeapWord*)obj; |
0 | 7333 if (_span.contains(addr) && !_verification_bm->isMarked(addr)) { |
7334 // Oop lies in _span and isn't yet grey or black | |
7335 _verification_bm->mark(addr); // now grey | |
7336 if (!_cms_bm->isMarked(addr)) { | |
7337 oop(addr)->print(); | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7338 gclog_or_tty->print_cr(" (" INTPTR_FORMAT " should have been marked)", |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7339 addr); |
0 | 7340 fatal("... aborting"); |
7341 } | |
7342 | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7343 if (!_mark_stack->push(obj)) { // stack overflow |
0 | 7344 if (PrintCMSStatistics != 0) { |
7345 gclog_or_tty->print_cr("CMS marking stack overflow (benign) at " | |
7346 SIZE_FORMAT, _mark_stack->capacity()); | |
7347 } | |
7348 assert(_mark_stack->isFull(), "Else push should have succeeded"); | |
7349 handle_stack_overflow(addr); | |
7350 } | |
7351 // anything including and to the right of _finger | |
7352 // will be scanned as we iterate over the remainder of the | |
7353 // bit map | |
7354 } | |
7355 } | |
7356 | |
7357 PushOrMarkClosure::PushOrMarkClosure(CMSCollector* collector, | |
7358 MemRegion span, | |
7359 CMSBitMap* bitMap, CMSMarkStack* markStack, | |
7360 CMSMarkStack* revisitStack, | |
7361 HeapWord* finger, MarkFromRootsClosure* parent) : | |
935 | 7362 KlassRememberingOopClosure(collector, collector->ref_processor(), revisitStack), |
0 | 7363 _span(span), |
7364 _bitMap(bitMap), | |
7365 _markStack(markStack), | |
7366 _finger(finger), | |
935 | 7367 _parent(parent) |
0 | 7368 { } |
7369 | |
7370 Par_PushOrMarkClosure::Par_PushOrMarkClosure(CMSCollector* collector, | |
7371 MemRegion span, | |
7372 CMSBitMap* bit_map, | |
7373 OopTaskQueue* work_queue, | |
7374 CMSMarkStack* overflow_stack, | |
7375 CMSMarkStack* revisit_stack, | |
7376 HeapWord* finger, | |
7377 HeapWord** global_finger_addr, | |
7378 Par_MarkFromRootsClosure* parent) : | |
935 | 7379 Par_KlassRememberingOopClosure(collector, |
7380 collector->ref_processor(), | |
7381 revisit_stack), | |
0 | 7382 _whole_span(collector->_span), |
7383 _span(span), | |
7384 _bit_map(bit_map), | |
7385 _work_queue(work_queue), | |
7386 _overflow_stack(overflow_stack), | |
7387 _finger(finger), | |
7388 _global_finger_addr(global_finger_addr), | |
935 | 7389 _parent(parent) |
0 | 7390 { } |
7391 | |
340
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
7392 // Assumes thread-safe access by callers, who are |
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
7393 // responsible for mutual exclusion. |
0 | 7394 void CMSCollector::lower_restart_addr(HeapWord* low) { |
7395 assert(_span.contains(low), "Out of bounds addr"); | |
7396 if (_restart_addr == NULL) { | |
7397 _restart_addr = low; | |
7398 } else { | |
7399 _restart_addr = MIN2(_restart_addr, low); | |
7400 } | |
7401 } | |
7402 | |
7403 // Upon stack overflow, we discard (part of) the stack, | |
7404 // remembering the least address amongst those discarded | |
7405 // in CMSCollector's _restart_address. | |
7406 void PushOrMarkClosure::handle_stack_overflow(HeapWord* lost) { | |
7407 // Remember the least grey address discarded | |
7408 HeapWord* ra = (HeapWord*)_markStack->least_value(lost); | |
7409 _collector->lower_restart_addr(ra); | |
7410 _markStack->reset(); // discard stack contents | |
7411 _markStack->expand(); // expand the stack if possible | |
7412 } | |
7413 | |
7414 // Upon stack overflow, we discard (part of) the stack, | |
7415 // remembering the least address amongst those discarded | |
7416 // in CMSCollector's _restart_address. | |
7417 void Par_PushOrMarkClosure::handle_stack_overflow(HeapWord* lost) { | |
7418 // We need to do this under a mutex to prevent other | |
340
ebeb6490b814
6722116: CMS: Incorrect overflow handling when using parallel concurrent marking
ysr
parents:
283
diff
changeset
|
7419 // workers from interfering with the work done below. |
0 | 7420 MutexLockerEx ml(_overflow_stack->par_lock(), |
7421 Mutex::_no_safepoint_check_flag); | |
7422 // Remember the least grey address discarded | |
7423 HeapWord* ra = (HeapWord*)_overflow_stack->least_value(lost); | |
7424 _collector->lower_restart_addr(ra); | |
7425 _overflow_stack->reset(); // discard stack contents | |
7426 _overflow_stack->expand(); // expand the stack if possible | |
7427 } | |
7428 | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7429 void PushOrMarkClosure::do_oop(oop obj) { |
0 | 7430 // Ignore mark word because we are running concurrent with mutators. |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7431 assert(obj->is_oop_or_null(true), "expected an oop or NULL"); |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7432 HeapWord* addr = (HeapWord*)obj; |
0 | 7433 if (_span.contains(addr) && !_bitMap->isMarked(addr)) { |
7434 // Oop lies in _span and isn't yet grey or black | |
7435 _bitMap->mark(addr); // now grey | |
7436 if (addr < _finger) { | |
7437 // the bit map iteration has already either passed, or | |
7438 // sampled, this bit in the bit map; we'll need to | |
7439 // use the marking stack to scan this oop's oops. | |
7440 bool simulate_overflow = false; | |
7441 NOT_PRODUCT( | |
7442 if (CMSMarkStackOverflowALot && | |
7443 _collector->simulate_overflow()) { | |
7444 // simulate a stack overflow | |
7445 simulate_overflow = true; | |
7446 } | |
7447 ) | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7448 if (simulate_overflow || !_markStack->push(obj)) { // stack overflow |
0 | 7449 if (PrintCMSStatistics != 0) { |
7450 gclog_or_tty->print_cr("CMS marking stack overflow (benign) at " | |
7451 SIZE_FORMAT, _markStack->capacity()); | |
7452 } | |
7453 assert(simulate_overflow || _markStack->isFull(), "Else push should have succeeded"); | |
7454 handle_stack_overflow(addr); | |
7455 } | |
7456 } | |
7457 // anything including and to the right of _finger | |
7458 // will be scanned as we iterate over the remainder of the | |
7459 // bit map | |
7460 do_yield_check(); | |
7461 } | |
7462 } | |
7463 | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7464 void PushOrMarkClosure::do_oop(oop* p) { PushOrMarkClosure::do_oop_work(p); } |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7465 void PushOrMarkClosure::do_oop(narrowOop* p) { PushOrMarkClosure::do_oop_work(p); } |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7466 |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7467 void Par_PushOrMarkClosure::do_oop(oop obj) { |
0 | 7468 // Ignore mark word because we are running concurrent with mutators. |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7469 assert(obj->is_oop_or_null(true), "expected an oop or NULL"); |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7470 HeapWord* addr = (HeapWord*)obj; |
0 | 7471 if (_whole_span.contains(addr) && !_bit_map->isMarked(addr)) { |
7472 // Oop lies in _span and isn't yet grey or black | |
7473 // We read the global_finger (volatile read) strictly after marking oop | |
7474 bool res = _bit_map->par_mark(addr); // now grey | |
7475 volatile HeapWord** gfa = (volatile HeapWord**)_global_finger_addr; | |
7476 // Should we push this marked oop on our stack? | |
7477 // -- if someone else marked it, nothing to do | |
7478 // -- if target oop is above global finger nothing to do | |
7479 // -- if target oop is in chunk and above local finger | |
7480 // then nothing to do | |
7481 // -- else push on work queue | |
7482 if ( !res // someone else marked it, they will deal with it | |
7483 || (addr >= *gfa) // will be scanned in a later task | |
7484 || (_span.contains(addr) && addr >= _finger)) { // later in this chunk | |
7485 return; | |
7486 } | |
7487 // the bit map iteration has already either passed, or | |
7488 // sampled, this bit in the bit map; we'll need to | |
7489 // use the marking stack to scan this oop's oops. | |
7490 bool simulate_overflow = false; | |
7491 NOT_PRODUCT( | |
7492 if (CMSMarkStackOverflowALot && | |
7493 _collector->simulate_overflow()) { | |
7494 // simulate a stack overflow | |
7495 simulate_overflow = true; | |
7496 } | |
7497 ) | |
7498 if (simulate_overflow || | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7499 !(_work_queue->push(obj) || _overflow_stack->par_push(obj))) { |
0 | 7500 // stack overflow |
7501 if (PrintCMSStatistics != 0) { | |
7502 gclog_or_tty->print_cr("CMS marking stack overflow (benign) at " | |
7503 SIZE_FORMAT, _overflow_stack->capacity()); | |
7504 } | |
7505 // We cannot assert that the overflow stack is full because | |
7506 // it may have been emptied since. | |
7507 assert(simulate_overflow || | |
7508 _work_queue->size() == _work_queue->max_elems(), | |
7509 "Else push should have succeeded"); | |
7510 handle_stack_overflow(addr); | |
7511 } | |
7512 do_yield_check(); | |
7513 } | |
7514 } | |
7515 | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7516 void Par_PushOrMarkClosure::do_oop(oop* p) { Par_PushOrMarkClosure::do_oop_work(p); } |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7517 void Par_PushOrMarkClosure::do_oop(narrowOop* p) { Par_PushOrMarkClosure::do_oop_work(p); } |
0 | 7518 |
935 | 7519 KlassRememberingOopClosure::KlassRememberingOopClosure(CMSCollector* collector, |
7520 ReferenceProcessor* rp, | |
7521 CMSMarkStack* revisit_stack) : | |
7522 OopClosure(rp), | |
7523 _collector(collector), | |
7524 _revisit_stack(revisit_stack), | |
7525 _should_remember_klasses(collector->should_unload_classes()) {} | |
7526 | |
0 | 7527 PushAndMarkClosure::PushAndMarkClosure(CMSCollector* collector, |
7528 MemRegion span, | |
7529 ReferenceProcessor* rp, | |
7530 CMSBitMap* bit_map, | |
7531 CMSBitMap* mod_union_table, | |
7532 CMSMarkStack* mark_stack, | |
7533 CMSMarkStack* revisit_stack, | |
7534 bool concurrent_precleaning): | |
935 | 7535 KlassRememberingOopClosure(collector, rp, revisit_stack), |
0 | 7536 _span(span), |
7537 _bit_map(bit_map), | |
7538 _mod_union_table(mod_union_table), | |
7539 _mark_stack(mark_stack), | |
935 | 7540 _concurrent_precleaning(concurrent_precleaning) |
0 | 7541 { |
7542 assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL"); | |
7543 } | |
7544 | |
7545 // Grey object rescan during pre-cleaning and second checkpoint phases -- | |
7546 // the non-parallel version (the parallel version appears further below.) | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7547 void PushAndMarkClosure::do_oop(oop obj) { |
342
37f87013dfd8
6711316: Open source the Garbage-First garbage collector
ysr
parents:
143
diff
changeset
|
7548 // Ignore mark word verification. If during concurrent precleaning, |
37f87013dfd8
6711316: Open source the Garbage-First garbage collector
ysr
parents:
143
diff
changeset
|
7549 // the object monitor may be locked. If during the checkpoint |
37f87013dfd8
6711316: Open source the Garbage-First garbage collector
ysr
parents:
143
diff
changeset
|
7550 // phases, the object may already have been reached by a different |
37f87013dfd8
6711316: Open source the Garbage-First garbage collector
ysr
parents:
143
diff
changeset
|
7551 // path and may be at the end of the global overflow list (so |
37f87013dfd8
6711316: Open source the Garbage-First garbage collector
ysr
parents:
143
diff
changeset
|
7552 // the mark word may be NULL). |
37f87013dfd8
6711316: Open source the Garbage-First garbage collector
ysr
parents:
143
diff
changeset
|
7553 assert(obj->is_oop_or_null(true /* ignore mark word */), |
0 | 7554 "expected an oop or NULL"); |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7555 HeapWord* addr = (HeapWord*)obj; |
0 | 7556 // Check if oop points into the CMS generation |
7557 // and is not marked | |
7558 if (_span.contains(addr) && !_bit_map->isMarked(addr)) { | |
7559 // a white object ... | |
7560 _bit_map->mark(addr); // ... now grey | |
7561 // push on the marking stack (grey set) | |
7562 bool simulate_overflow = false; | |
7563 NOT_PRODUCT( | |
7564 if (CMSMarkStackOverflowALot && | |
7565 _collector->simulate_overflow()) { | |
7566 // simulate a stack overflow | |
7567 simulate_overflow = true; | |
7568 } | |
7569 ) | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7570 if (simulate_overflow || !_mark_stack->push(obj)) { |
0 | 7571 if (_concurrent_precleaning) { |
283
9199f248b0ee
6722112: CMS: Incorrect encoding of overflown object arrays during concurrent precleaning
ysr
parents:
271
diff
changeset
|
7572 // During precleaning we can just dirty the appropriate card(s) |
0 | 7573 // in the mod union table, thus ensuring that the object remains |
283
9199f248b0ee
6722112: CMS: Incorrect encoding of overflown object arrays during concurrent precleaning
ysr
parents:
271
diff
changeset
|
7574 // in the grey set and continue. In the case of object arrays |
9199f248b0ee
6722112: CMS: Incorrect encoding of overflown object arrays during concurrent precleaning
ysr
parents:
271
diff
changeset
|
7575 // we need to dirty all of the cards that the object spans, |
9199f248b0ee
6722112: CMS: Incorrect encoding of overflown object arrays during concurrent precleaning
ysr
parents:
271
diff
changeset
|
7576 // since the rescan of object arrays will be limited to the |
9199f248b0ee
6722112: CMS: Incorrect encoding of overflown object arrays during concurrent precleaning
ysr
parents:
271
diff
changeset
|
7577 // dirty cards. |
9199f248b0ee
6722112: CMS: Incorrect encoding of overflown object arrays during concurrent precleaning
ysr
parents:
271
diff
changeset
|
7578 // Note that no one can be intefering with us in this action |
9199f248b0ee
6722112: CMS: Incorrect encoding of overflown object arrays during concurrent precleaning
ysr
parents:
271
diff
changeset
|
7579 // of dirtying the mod union table, so no locking or atomics |
9199f248b0ee
6722112: CMS: Incorrect encoding of overflown object arrays during concurrent precleaning
ysr
parents:
271
diff
changeset
|
7580 // are required. |
9199f248b0ee
6722112: CMS: Incorrect encoding of overflown object arrays during concurrent precleaning
ysr
parents:
271
diff
changeset
|
7581 if (obj->is_objArray()) { |
9199f248b0ee
6722112: CMS: Incorrect encoding of overflown object arrays during concurrent precleaning
ysr
parents:
271
diff
changeset
|
7582 size_t sz = obj->size(); |
9199f248b0ee
6722112: CMS: Incorrect encoding of overflown object arrays during concurrent precleaning
ysr
parents:
271
diff
changeset
|
7583 HeapWord* end_card_addr = (HeapWord*)round_to( |
9199f248b0ee
6722112: CMS: Incorrect encoding of overflown object arrays during concurrent precleaning
ysr
parents:
271
diff
changeset
|
7584 (intptr_t)(addr+sz), CardTableModRefBS::card_size); |
9199f248b0ee
6722112: CMS: Incorrect encoding of overflown object arrays during concurrent precleaning
ysr
parents:
271
diff
changeset
|
7585 MemRegion redirty_range = MemRegion(addr, end_card_addr); |
9199f248b0ee
6722112: CMS: Incorrect encoding of overflown object arrays during concurrent precleaning
ysr
parents:
271
diff
changeset
|
7586 assert(!redirty_range.is_empty(), "Arithmetical tautology"); |
9199f248b0ee
6722112: CMS: Incorrect encoding of overflown object arrays during concurrent precleaning
ysr
parents:
271
diff
changeset
|
7587 _mod_union_table->mark_range(redirty_range); |
9199f248b0ee
6722112: CMS: Incorrect encoding of overflown object arrays during concurrent precleaning
ysr
parents:
271
diff
changeset
|
7588 } else { |
9199f248b0ee
6722112: CMS: Incorrect encoding of overflown object arrays during concurrent precleaning
ysr
parents:
271
diff
changeset
|
7589 _mod_union_table->mark(addr); |
9199f248b0ee
6722112: CMS: Incorrect encoding of overflown object arrays during concurrent precleaning
ysr
parents:
271
diff
changeset
|
7590 } |
0 | 7591 _collector->_ser_pmc_preclean_ovflw++; |
7592 } else { | |
7593 // During the remark phase, we need to remember this oop | |
7594 // in the overflow list. | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7595 _collector->push_on_overflow_list(obj); |
0 | 7596 _collector->_ser_pmc_remark_ovflw++; |
7597 } | |
7598 } | |
7599 } | |
7600 } | |
7601 | |
7602 Par_PushAndMarkClosure::Par_PushAndMarkClosure(CMSCollector* collector, | |
7603 MemRegion span, | |
7604 ReferenceProcessor* rp, | |
7605 CMSBitMap* bit_map, | |
7606 OopTaskQueue* work_queue, | |
7607 CMSMarkStack* revisit_stack): | |
935 | 7608 Par_KlassRememberingOopClosure(collector, rp, revisit_stack), |
0 | 7609 _span(span), |
7610 _bit_map(bit_map), | |
935 | 7611 _work_queue(work_queue) |
0 | 7612 { |
7613 assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL"); | |
7614 } | |
7615 | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7616 void PushAndMarkClosure::do_oop(oop* p) { PushAndMarkClosure::do_oop_work(p); } |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7617 void PushAndMarkClosure::do_oop(narrowOop* p) { PushAndMarkClosure::do_oop_work(p); } |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7618 |
0 | 7619 // Grey object rescan during second checkpoint phase -- |
7620 // the parallel version. | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7621 void Par_PushAndMarkClosure::do_oop(oop obj) { |
0 | 7622 // In the assert below, we ignore the mark word because |
7623 // this oop may point to an already visited object that is | |
7624 // on the overflow stack (in which case the mark word has | |
7625 // been hijacked for chaining into the overflow stack -- | |
7626 // if this is the last object in the overflow stack then | |
7627 // its mark word will be NULL). Because this object may | |
7628 // have been subsequently popped off the global overflow | |
7629 // stack, and the mark word possibly restored to the prototypical | |
7630 // value, by the time we get to examined this failing assert in | |
7631 // the debugger, is_oop_or_null(false) may subsequently start | |
7632 // to hold. | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7633 assert(obj->is_oop_or_null(true), |
0 | 7634 "expected an oop or NULL"); |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7635 HeapWord* addr = (HeapWord*)obj; |
0 | 7636 // Check if oop points into the CMS generation |
7637 // and is not marked | |
7638 if (_span.contains(addr) && !_bit_map->isMarked(addr)) { | |
7639 // a white object ... | |
7640 // If we manage to "claim" the object, by being the | |
7641 // first thread to mark it, then we push it on our | |
7642 // marking stack | |
7643 if (_bit_map->par_mark(addr)) { // ... now grey | |
7644 // push on work queue (grey set) | |
7645 bool simulate_overflow = false; | |
7646 NOT_PRODUCT( | |
7647 if (CMSMarkStackOverflowALot && | |
7648 _collector->par_simulate_overflow()) { | |
7649 // simulate a stack overflow | |
7650 simulate_overflow = true; | |
7651 } | |
7652 ) | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7653 if (simulate_overflow || !_work_queue->push(obj)) { |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7654 _collector->par_push_on_overflow_list(obj); |
0 | 7655 _collector->_par_pmc_remark_ovflw++; // imprecise OK: no need to CAS |
7656 } | |
7657 } // Else, some other thread got there first | |
7658 } | |
7659 } | |
7660 | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7661 void Par_PushAndMarkClosure::do_oop(oop* p) { Par_PushAndMarkClosure::do_oop_work(p); } |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7662 void Par_PushAndMarkClosure::do_oop(narrowOop* p) { Par_PushAndMarkClosure::do_oop_work(p); } |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
7663 |
941 | 7664 void PushAndMarkClosure::remember_mdo(DataLayout* v) { |
7665 // TBD | |
7666 } | |
7667 | |
7668 void Par_PushAndMarkClosure::remember_mdo(DataLayout* v) { | |
7669 // TBD | |
7670 } | |
7671 | |
0 | 7672 void CMSPrecleanRefsYieldClosure::do_yield_work() { |
935 | 7673 DEBUG_ONLY(RememberKlassesChecker mux(false);) |
0 | 7674 Mutex* bml = _collector->bitMapLock(); |
7675 assert_lock_strong(bml); | |
7676 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
7677 "CMS thread should hold CMS token"); | |
7678 | |
7679 bml->unlock(); | |
7680 ConcurrentMarkSweepThread::desynchronize(true); | |
7681 | |
7682 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
7683 | |
7684 _collector->stopTimer(); | |
7685 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
7686 if (PrintCMSStatistics != 0) { | |
7687 _collector->incrementYields(); | |
7688 } | |
7689 _collector->icms_wait(); | |
7690 | |
7691 // See the comment in coordinator_yield() | |
7692 for (unsigned i = 0; i < CMSYieldSleepCount && | |
7693 ConcurrentMarkSweepThread::should_yield() && | |
7694 !CMSCollector::foregroundGCIsActive(); ++i) { | |
7695 os::sleep(Thread::current(), 1, false); | |
7696 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
7697 } | |
7698 | |
7699 ConcurrentMarkSweepThread::synchronize(true); | |
7700 bml->lock(); | |
7701 | |
7702 _collector->startTimer(); | |
7703 } | |
7704 | |
7705 bool CMSPrecleanRefsYieldClosure::should_return() { | |
7706 if (ConcurrentMarkSweepThread::should_yield()) { | |
7707 do_yield_work(); | |
7708 } | |
7709 return _collector->foregroundGCIsActive(); | |
7710 } | |
7711 | |
7712 void MarkFromDirtyCardsClosure::do_MemRegion(MemRegion mr) { | |
7713 assert(((size_t)mr.start())%CardTableModRefBS::card_size_in_words == 0, | |
7714 "mr should be aligned to start at a card boundary"); | |
7715 // We'd like to assert: | |
7716 // assert(mr.word_size()%CardTableModRefBS::card_size_in_words == 0, | |
7717 // "mr should be a range of cards"); | |
7718 // However, that would be too strong in one case -- the last | |
7719 // partition ends at _unallocated_block which, in general, can be | |
7720 // an arbitrary boundary, not necessarily card aligned. | |
7721 if (PrintCMSStatistics != 0) { | |
7722 _num_dirty_cards += | |
7723 mr.word_size()/CardTableModRefBS::card_size_in_words; | |
7724 } | |
7725 _space->object_iterate_mem(mr, &_scan_cl); | |
7726 } | |
7727 | |
7728 SweepClosure::SweepClosure(CMSCollector* collector, | |
7729 ConcurrentMarkSweepGeneration* g, | |
7730 CMSBitMap* bitMap, bool should_yield) : | |
7731 _collector(collector), | |
7732 _g(g), | |
7733 _sp(g->cmsSpace()), | |
7734 _limit(_sp->sweep_limit()), | |
7735 _freelistLock(_sp->freelistLock()), | |
7736 _bitMap(bitMap), | |
7737 _yield(should_yield), | |
7738 _inFreeRange(false), // No free range at beginning of sweep | |
7739 _freeRangeInFreeLists(false), // No free range at beginning of sweep | |
7740 _lastFreeRangeCoalesced(false), | |
7741 _freeFinger(g->used_region().start()) | |
7742 { | |
7743 NOT_PRODUCT( | |
7744 _numObjectsFreed = 0; | |
7745 _numWordsFreed = 0; | |
7746 _numObjectsLive = 0; | |
7747 _numWordsLive = 0; | |
7748 _numObjectsAlreadyFree = 0; | |
7749 _numWordsAlreadyFree = 0; | |
7750 _last_fc = NULL; | |
7751 | |
7752 _sp->initializeIndexedFreeListArrayReturnedBytes(); | |
7753 _sp->dictionary()->initializeDictReturnedBytes(); | |
7754 ) | |
7755 assert(_limit >= _sp->bottom() && _limit <= _sp->end(), | |
7756 "sweep _limit out of bounds"); | |
7757 if (CMSTraceSweeper) { | |
7758 gclog_or_tty->print("\n====================\nStarting new sweep\n"); | |
7759 } | |
7760 } | |
7761 | |
7762 // We need this destructor to reclaim any space at the end | |
7763 // of the space, which do_blk below may not have added back to | |
7764 // the free lists. [basically dealing with the "fringe effect"] | |
7765 SweepClosure::~SweepClosure() { | |
7766 assert_lock_strong(_freelistLock); | |
7767 // this should be treated as the end of a free run if any | |
7768 // The current free range should be returned to the free lists | |
7769 // as one coalesced chunk. | |
7770 if (inFreeRange()) { | |
7771 flushCurFreeChunk(freeFinger(), | |
7772 pointer_delta(_limit, freeFinger())); | |
7773 assert(freeFinger() < _limit, "the finger pointeth off base"); | |
7774 if (CMSTraceSweeper) { | |
7775 gclog_or_tty->print("destructor:"); | |
7776 gclog_or_tty->print("Sweep:put_free_blk 0x%x ("SIZE_FORMAT") " | |
7777 "[coalesced:"SIZE_FORMAT"]\n", | |
7778 freeFinger(), pointer_delta(_limit, freeFinger()), | |
7779 lastFreeRangeCoalesced()); | |
7780 } | |
7781 } | |
7782 NOT_PRODUCT( | |
7783 if (Verbose && PrintGC) { | |
7784 gclog_or_tty->print("Collected "SIZE_FORMAT" objects, " | |
7785 SIZE_FORMAT " bytes", | |
7786 _numObjectsFreed, _numWordsFreed*sizeof(HeapWord)); | |
7787 gclog_or_tty->print_cr("\nLive "SIZE_FORMAT" objects, " | |
7788 SIZE_FORMAT" bytes " | |
7789 "Already free "SIZE_FORMAT" objects, "SIZE_FORMAT" bytes", | |
7790 _numObjectsLive, _numWordsLive*sizeof(HeapWord), | |
7791 _numObjectsAlreadyFree, _numWordsAlreadyFree*sizeof(HeapWord)); | |
7792 size_t totalBytes = (_numWordsFreed + _numWordsLive + _numWordsAlreadyFree) * | |
7793 sizeof(HeapWord); | |
7794 gclog_or_tty->print_cr("Total sweep: "SIZE_FORMAT" bytes", totalBytes); | |
7795 | |
7796 if (PrintCMSStatistics && CMSVerifyReturnedBytes) { | |
7797 size_t indexListReturnedBytes = _sp->sumIndexedFreeListArrayReturnedBytes(); | |
7798 size_t dictReturnedBytes = _sp->dictionary()->sumDictReturnedBytes(); | |
7799 size_t returnedBytes = indexListReturnedBytes + dictReturnedBytes; | |
7800 gclog_or_tty->print("Returned "SIZE_FORMAT" bytes", returnedBytes); | |
7801 gclog_or_tty->print(" Indexed List Returned "SIZE_FORMAT" bytes", | |
7802 indexListReturnedBytes); | |
7803 gclog_or_tty->print_cr(" Dictionary Returned "SIZE_FORMAT" bytes", | |
7804 dictReturnedBytes); | |
7805 } | |
7806 } | |
7807 ) | |
7808 // Now, in debug mode, just null out the sweep_limit | |
7809 NOT_PRODUCT(_sp->clear_sweep_limit();) | |
7810 if (CMSTraceSweeper) { | |
7811 gclog_or_tty->print("end of sweep\n================\n"); | |
7812 } | |
7813 } | |
7814 | |
7815 void SweepClosure::initialize_free_range(HeapWord* freeFinger, | |
7816 bool freeRangeInFreeLists) { | |
7817 if (CMSTraceSweeper) { | |
7818 gclog_or_tty->print("---- Start free range 0x%x with free block [%d] (%d)\n", | |
7819 freeFinger, _sp->block_size(freeFinger), | |
7820 freeRangeInFreeLists); | |
7821 } | |
7822 assert(!inFreeRange(), "Trampling existing free range"); | |
7823 set_inFreeRange(true); | |
7824 set_lastFreeRangeCoalesced(false); | |
7825 | |
7826 set_freeFinger(freeFinger); | |
7827 set_freeRangeInFreeLists(freeRangeInFreeLists); | |
7828 if (CMSTestInFreeList) { | |
7829 if (freeRangeInFreeLists) { | |
7830 FreeChunk* fc = (FreeChunk*) freeFinger; | |
7831 assert(fc->isFree(), "A chunk on the free list should be free."); | |
7832 assert(fc->size() > 0, "Free range should have a size"); | |
7833 assert(_sp->verifyChunkInFreeLists(fc), "Chunk is not in free lists"); | |
7834 } | |
7835 } | |
7836 } | |
7837 | |
7838 // Note that the sweeper runs concurrently with mutators. Thus, | |
7839 // it is possible for direct allocation in this generation to happen | |
7840 // in the middle of the sweep. Note that the sweeper also coalesces | |
7841 // contiguous free blocks. Thus, unless the sweeper and the allocator | |
7842 // synchronize appropriately freshly allocated blocks may get swept up. | |
7843 // This is accomplished by the sweeper locking the free lists while | |
7844 // it is sweeping. Thus blocks that are determined to be free are | |
7845 // indeed free. There is however one additional complication: | |
7846 // blocks that have been allocated since the final checkpoint and | |
7847 // mark, will not have been marked and so would be treated as | |
7848 // unreachable and swept up. To prevent this, the allocator marks | |
7849 // the bit map when allocating during the sweep phase. This leads, | |
7850 // however, to a further complication -- objects may have been allocated | |
7851 // but not yet initialized -- in the sense that the header isn't yet | |
7852 // installed. The sweeper can not then determine the size of the block | |
7853 // in order to skip over it. To deal with this case, we use a technique | |
7854 // (due to Printezis) to encode such uninitialized block sizes in the | |
7855 // bit map. Since the bit map uses a bit per every HeapWord, but the | |
7856 // CMS generation has a minimum object size of 3 HeapWords, it follows | |
7857 // that "normal marks" won't be adjacent in the bit map (there will | |
7858 // always be at least two 0 bits between successive 1 bits). We make use | |
7859 // of these "unused" bits to represent uninitialized blocks -- the bit | |
7860 // corresponding to the start of the uninitialized object and the next | |
7861 // bit are both set. Finally, a 1 bit marks the end of the object that | |
7862 // started with the two consecutive 1 bits to indicate its potentially | |
7863 // uninitialized state. | |
7864 | |
7865 size_t SweepClosure::do_blk_careful(HeapWord* addr) { | |
7866 FreeChunk* fc = (FreeChunk*)addr; | |
7867 size_t res; | |
7868 | |
7869 // check if we are done sweepinrg | |
7870 if (addr == _limit) { // we have swept up to the limit, do nothing more | |
7871 assert(_limit >= _sp->bottom() && _limit <= _sp->end(), | |
7872 "sweep _limit out of bounds"); | |
7873 // help the closure application finish | |
7874 return pointer_delta(_sp->end(), _limit); | |
7875 } | |
7876 assert(addr <= _limit, "sweep invariant"); | |
7877 | |
7878 // check if we should yield | |
7879 do_yield_check(addr); | |
7880 if (fc->isFree()) { | |
7881 // Chunk that is already free | |
7882 res = fc->size(); | |
7883 doAlreadyFreeChunk(fc); | |
7884 debug_only(_sp->verifyFreeLists()); | |
7885 assert(res == fc->size(), "Don't expect the size to change"); | |
7886 NOT_PRODUCT( | |
7887 _numObjectsAlreadyFree++; | |
7888 _numWordsAlreadyFree += res; | |
7889 ) | |
7890 NOT_PRODUCT(_last_fc = fc;) | |
7891 } else if (!_bitMap->isMarked(addr)) { | |
7892 // Chunk is fresh garbage | |
7893 res = doGarbageChunk(fc); | |
7894 debug_only(_sp->verifyFreeLists()); | |
7895 NOT_PRODUCT( | |
7896 _numObjectsFreed++; | |
7897 _numWordsFreed += res; | |
7898 ) | |
7899 } else { | |
7900 // Chunk that is alive. | |
7901 res = doLiveChunk(fc); | |
7902 debug_only(_sp->verifyFreeLists()); | |
7903 NOT_PRODUCT( | |
7904 _numObjectsLive++; | |
7905 _numWordsLive += res; | |
7906 ) | |
7907 } | |
7908 return res; | |
7909 } | |
7910 | |
7911 // For the smart allocation, record following | |
7912 // split deaths - a free chunk is removed from its free list because | |
7913 // it is being split into two or more chunks. | |
7914 // split birth - a free chunk is being added to its free list because | |
7915 // a larger free chunk has been split and resulted in this free chunk. | |
7916 // coal death - a free chunk is being removed from its free list because | |
7917 // it is being coalesced into a large free chunk. | |
7918 // coal birth - a free chunk is being added to its free list because | |
7919 // it was created when two or more free chunks where coalesced into | |
7920 // this free chunk. | |
7921 // | |
7922 // These statistics are used to determine the desired number of free | |
7923 // chunks of a given size. The desired number is chosen to be relative | |
7924 // to the end of a CMS sweep. The desired number at the end of a sweep | |
7925 // is the | |
7926 // count-at-end-of-previous-sweep (an amount that was enough) | |
7927 // - count-at-beginning-of-current-sweep (the excess) | |
7928 // + split-births (gains in this size during interval) | |
7929 // - split-deaths (demands on this size during interval) | |
7930 // where the interval is from the end of one sweep to the end of the | |
7931 // next. | |
7932 // | |
7933 // When sweeping the sweeper maintains an accumulated chunk which is | |
7934 // the chunk that is made up of chunks that have been coalesced. That | |
7935 // will be termed the left-hand chunk. A new chunk of garbage that | |
7936 // is being considered for coalescing will be referred to as the | |
7937 // right-hand chunk. | |
7938 // | |
7939 // When making a decision on whether to coalesce a right-hand chunk with | |
7940 // the current left-hand chunk, the current count vs. the desired count | |
7941 // of the left-hand chunk is considered. Also if the right-hand chunk | |
7942 // is near the large chunk at the end of the heap (see | |
7943 // ConcurrentMarkSweepGeneration::isNearLargestChunk()), then the | |
7944 // left-hand chunk is coalesced. | |
7945 // | |
7946 // When making a decision about whether to split a chunk, the desired count | |
7947 // vs. the current count of the candidate to be split is also considered. | |
7948 // If the candidate is underpopulated (currently fewer chunks than desired) | |
7949 // a chunk of an overpopulated (currently more chunks than desired) size may | |
7950 // be chosen. The "hint" associated with a free list, if non-null, points | |
7951 // to a free list which may be overpopulated. | |
7952 // | |
7953 | |
7954 void SweepClosure::doAlreadyFreeChunk(FreeChunk* fc) { | |
7955 size_t size = fc->size(); | |
7956 // Chunks that cannot be coalesced are not in the | |
7957 // free lists. | |
7958 if (CMSTestInFreeList && !fc->cantCoalesce()) { | |
7959 assert(_sp->verifyChunkInFreeLists(fc), | |
7960 "free chunk should be in free lists"); | |
7961 } | |
7962 // a chunk that is already free, should not have been | |
7963 // marked in the bit map | |
7964 HeapWord* addr = (HeapWord*) fc; | |
7965 assert(!_bitMap->isMarked(addr), "free chunk should be unmarked"); | |
7966 // Verify that the bit map has no bits marked between | |
7967 // addr and purported end of this block. | |
7968 _bitMap->verifyNoOneBitsInRange(addr + 1, addr + size); | |
7969 | |
7970 // Some chunks cannot be coalesced in under any circumstances. | |
7971 // See the definition of cantCoalesce(). | |
7972 if (!fc->cantCoalesce()) { | |
7973 // This chunk can potentially be coalesced. | |
7974 if (_sp->adaptive_freelists()) { | |
7975 // All the work is done in | |
7976 doPostIsFreeOrGarbageChunk(fc, size); | |
7977 } else { // Not adaptive free lists | |
7978 // this is a free chunk that can potentially be coalesced by the sweeper; | |
7979 if (!inFreeRange()) { | |
7980 // if the next chunk is a free block that can't be coalesced | |
7981 // it doesn't make sense to remove this chunk from the free lists | |
7982 FreeChunk* nextChunk = (FreeChunk*)(addr + size); | |
7983 assert((HeapWord*)nextChunk <= _limit, "sweep invariant"); | |
7984 if ((HeapWord*)nextChunk < _limit && // there's a next chunk... | |
7985 nextChunk->isFree() && // which is free... | |
7986 nextChunk->cantCoalesce()) { // ... but cant be coalesced | |
7987 // nothing to do | |
7988 } else { | |
7989 // Potentially the start of a new free range: | |
7990 // Don't eagerly remove it from the free lists. | |
7991 // No need to remove it if it will just be put | |
7992 // back again. (Also from a pragmatic point of view | |
7993 // if it is a free block in a region that is beyond | |
7994 // any allocated blocks, an assertion will fail) | |
7995 // Remember the start of a free run. | |
7996 initialize_free_range(addr, true); | |
7997 // end - can coalesce with next chunk | |
7998 } | |
7999 } else { | |
8000 // the midst of a free range, we are coalescing | |
8001 debug_only(record_free_block_coalesced(fc);) | |
8002 if (CMSTraceSweeper) { | |
8003 gclog_or_tty->print(" -- pick up free block 0x%x (%d)\n", fc, size); | |
8004 } | |
8005 // remove it from the free lists | |
8006 _sp->removeFreeChunkFromFreeLists(fc); | |
8007 set_lastFreeRangeCoalesced(true); | |
8008 // If the chunk is being coalesced and the current free range is | |
8009 // in the free lists, remove the current free range so that it | |
8010 // will be returned to the free lists in its entirety - all | |
8011 // the coalesced pieces included. | |
8012 if (freeRangeInFreeLists()) { | |
8013 FreeChunk* ffc = (FreeChunk*) freeFinger(); | |
8014 assert(ffc->size() == pointer_delta(addr, freeFinger()), | |
8015 "Size of free range is inconsistent with chunk size."); | |
8016 if (CMSTestInFreeList) { | |
8017 assert(_sp->verifyChunkInFreeLists(ffc), | |
8018 "free range is not in free lists"); | |
8019 } | |
8020 _sp->removeFreeChunkFromFreeLists(ffc); | |
8021 set_freeRangeInFreeLists(false); | |
8022 } | |
8023 } | |
8024 } | |
8025 } else { | |
8026 // Code path common to both original and adaptive free lists. | |
8027 | |
8028 // cant coalesce with previous block; this should be treated | |
8029 // as the end of a free run if any | |
8030 if (inFreeRange()) { | |
8031 // we kicked some butt; time to pick up the garbage | |
8032 assert(freeFinger() < addr, "the finger pointeth off base"); | |
8033 flushCurFreeChunk(freeFinger(), pointer_delta(addr, freeFinger())); | |
8034 } | |
8035 // else, nothing to do, just continue | |
8036 } | |
8037 } | |
8038 | |
8039 size_t SweepClosure::doGarbageChunk(FreeChunk* fc) { | |
8040 // This is a chunk of garbage. It is not in any free list. | |
8041 // Add it to a free list or let it possibly be coalesced into | |
8042 // a larger chunk. | |
8043 HeapWord* addr = (HeapWord*) fc; | |
8044 size_t size = CompactibleFreeListSpace::adjustObjectSize(oop(addr)->size()); | |
8045 | |
8046 if (_sp->adaptive_freelists()) { | |
8047 // Verify that the bit map has no bits marked between | |
8048 // addr and purported end of just dead object. | |
8049 _bitMap->verifyNoOneBitsInRange(addr + 1, addr + size); | |
8050 | |
8051 doPostIsFreeOrGarbageChunk(fc, size); | |
8052 } else { | |
8053 if (!inFreeRange()) { | |
8054 // start of a new free range | |
8055 assert(size > 0, "A free range should have a size"); | |
8056 initialize_free_range(addr, false); | |
8057 | |
8058 } else { | |
8059 // this will be swept up when we hit the end of the | |
8060 // free range | |
8061 if (CMSTraceSweeper) { | |
8062 gclog_or_tty->print(" -- pick up garbage 0x%x (%d) \n", fc, size); | |
8063 } | |
8064 // If the chunk is being coalesced and the current free range is | |
8065 // in the free lists, remove the current free range so that it | |
8066 // will be returned to the free lists in its entirety - all | |
8067 // the coalesced pieces included. | |
8068 if (freeRangeInFreeLists()) { | |
8069 FreeChunk* ffc = (FreeChunk*)freeFinger(); | |
8070 assert(ffc->size() == pointer_delta(addr, freeFinger()), | |
8071 "Size of free range is inconsistent with chunk size."); | |
8072 if (CMSTestInFreeList) { | |
8073 assert(_sp->verifyChunkInFreeLists(ffc), | |
8074 "free range is not in free lists"); | |
8075 } | |
8076 _sp->removeFreeChunkFromFreeLists(ffc); | |
8077 set_freeRangeInFreeLists(false); | |
8078 } | |
8079 set_lastFreeRangeCoalesced(true); | |
8080 } | |
8081 // this will be swept up when we hit the end of the free range | |
8082 | |
8083 // Verify that the bit map has no bits marked between | |
8084 // addr and purported end of just dead object. | |
8085 _bitMap->verifyNoOneBitsInRange(addr + 1, addr + size); | |
8086 } | |
8087 return size; | |
8088 } | |
8089 | |
8090 size_t SweepClosure::doLiveChunk(FreeChunk* fc) { | |
8091 HeapWord* addr = (HeapWord*) fc; | |
8092 // The sweeper has just found a live object. Return any accumulated | |
8093 // left hand chunk to the free lists. | |
8094 if (inFreeRange()) { | |
8095 if (_sp->adaptive_freelists()) { | |
8096 flushCurFreeChunk(freeFinger(), | |
8097 pointer_delta(addr, freeFinger())); | |
8098 } else { // not adaptive freelists | |
8099 set_inFreeRange(false); | |
8100 // Add the free range back to the free list if it is not already | |
8101 // there. | |
8102 if (!freeRangeInFreeLists()) { | |
8103 assert(freeFinger() < addr, "the finger pointeth off base"); | |
8104 if (CMSTraceSweeper) { | |
8105 gclog_or_tty->print("Sweep:put_free_blk 0x%x (%d) " | |
8106 "[coalesced:%d]\n", | |
8107 freeFinger(), pointer_delta(addr, freeFinger()), | |
8108 lastFreeRangeCoalesced()); | |
8109 } | |
8110 _sp->addChunkAndRepairOffsetTable(freeFinger(), | |
8111 pointer_delta(addr, freeFinger()), lastFreeRangeCoalesced()); | |
8112 } | |
8113 } | |
8114 } | |
8115 | |
8116 // Common code path for original and adaptive free lists. | |
8117 | |
8118 // this object is live: we'd normally expect this to be | |
8119 // an oop, and like to assert the following: | |
8120 // assert(oop(addr)->is_oop(), "live block should be an oop"); | |
8121 // However, as we commented above, this may be an object whose | |
8122 // header hasn't yet been initialized. | |
8123 size_t size; | |
8124 assert(_bitMap->isMarked(addr), "Tautology for this control point"); | |
8125 if (_bitMap->isMarked(addr + 1)) { | |
8126 // Determine the size from the bit map, rather than trying to | |
8127 // compute it from the object header. | |
8128 HeapWord* nextOneAddr = _bitMap->getNextMarkedWordAddress(addr + 2); | |
8129 size = pointer_delta(nextOneAddr + 1, addr); | |
8130 assert(size == CompactibleFreeListSpace::adjustObjectSize(size), | |
8131 "alignment problem"); | |
8132 | |
8133 #ifdef DEBUG | |
187 | 8134 if (oop(addr)->klass_or_null() != NULL && |
94
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
8135 ( !_collector->should_unload_classes() |
518
0af8b0718fc9
6692899: CMS: many vm.parallel_class_loading tests fail with assert "missing Printezis mark"
jmasa
parents:
517
diff
changeset
|
8136 || (oop(addr)->is_parsable()) && |
0af8b0718fc9
6692899: CMS: many vm.parallel_class_loading tests fail with assert "missing Printezis mark"
jmasa
parents:
517
diff
changeset
|
8137 oop(addr)->is_conc_safe())) { |
0 | 8138 // Ignore mark word because we are running concurrent with mutators |
8139 assert(oop(addr)->is_oop(true), "live block should be an oop"); | |
518
0af8b0718fc9
6692899: CMS: many vm.parallel_class_loading tests fail with assert "missing Printezis mark"
jmasa
parents:
517
diff
changeset
|
8140 // is_conc_safe is checked before performing this assertion |
0af8b0718fc9
6692899: CMS: many vm.parallel_class_loading tests fail with assert "missing Printezis mark"
jmasa
parents:
517
diff
changeset
|
8141 // because an object that is not is_conc_safe may yet have |
0af8b0718fc9
6692899: CMS: many vm.parallel_class_loading tests fail with assert "missing Printezis mark"
jmasa
parents:
517
diff
changeset
|
8142 // the return from size() correct. |
0 | 8143 assert(size == |
8144 CompactibleFreeListSpace::adjustObjectSize(oop(addr)->size()), | |
8145 "P-mark and computed size do not agree"); | |
8146 } | |
8147 #endif | |
8148 | |
8149 } else { | |
8150 // This should be an initialized object that's alive. | |
187 | 8151 assert(oop(addr)->klass_or_null() != NULL && |
94
0834225a7916
6634032: CMS: Need CMSInitiatingPermOccupancyFraction for perm, divorcing from CMSInitiatingOccupancyFraction
ysr
parents:
9
diff
changeset
|
8152 (!_collector->should_unload_classes() |
0 | 8153 || oop(addr)->is_parsable()), |
8154 "Should be an initialized object"); | |
518
0af8b0718fc9
6692899: CMS: many vm.parallel_class_loading tests fail with assert "missing Printezis mark"
jmasa
parents:
517
diff
changeset
|
8155 // Note that there are objects used during class redefinition |
0af8b0718fc9
6692899: CMS: many vm.parallel_class_loading tests fail with assert "missing Printezis mark"
jmasa
parents:
517
diff
changeset
|
8156 // (e.g., merge_cp in VM_RedefineClasses::merge_cp_and_rewrite() |
0af8b0718fc9
6692899: CMS: many vm.parallel_class_loading tests fail with assert "missing Printezis mark"
jmasa
parents:
517
diff
changeset
|
8157 // which are discarded with their is_conc_safe state still |
0af8b0718fc9
6692899: CMS: many vm.parallel_class_loading tests fail with assert "missing Printezis mark"
jmasa
parents:
517
diff
changeset
|
8158 // false. These object may be floating garbage so may be |
0af8b0718fc9
6692899: CMS: many vm.parallel_class_loading tests fail with assert "missing Printezis mark"
jmasa
parents:
517
diff
changeset
|
8159 // seen here. If they are floating garbage their size |
0af8b0718fc9
6692899: CMS: many vm.parallel_class_loading tests fail with assert "missing Printezis mark"
jmasa
parents:
517
diff
changeset
|
8160 // should be attainable from their klass. Do not that |
0af8b0718fc9
6692899: CMS: many vm.parallel_class_loading tests fail with assert "missing Printezis mark"
jmasa
parents:
517
diff
changeset
|
8161 // is_conc_safe() is true for oop(addr). |
0 | 8162 // Ignore mark word because we are running concurrent with mutators |
8163 assert(oop(addr)->is_oop(true), "live block should be an oop"); | |
8164 // Verify that the bit map has no bits marked between | |
8165 // addr and purported end of this block. | |
8166 size = CompactibleFreeListSpace::adjustObjectSize(oop(addr)->size()); | |
8167 assert(size >= 3, "Necessary for Printezis marks to work"); | |
8168 assert(!_bitMap->isMarked(addr+1), "Tautology for this control point"); | |
8169 DEBUG_ONLY(_bitMap->verifyNoOneBitsInRange(addr+2, addr+size);) | |
8170 } | |
8171 return size; | |
8172 } | |
8173 | |
8174 void SweepClosure::doPostIsFreeOrGarbageChunk(FreeChunk* fc, | |
8175 size_t chunkSize) { | |
8176 // doPostIsFreeOrGarbageChunk() should only be called in the smart allocation | |
8177 // scheme. | |
8178 bool fcInFreeLists = fc->isFree(); | |
8179 assert(_sp->adaptive_freelists(), "Should only be used in this case."); | |
8180 assert((HeapWord*)fc <= _limit, "sweep invariant"); | |
8181 if (CMSTestInFreeList && fcInFreeLists) { | |
8182 assert(_sp->verifyChunkInFreeLists(fc), | |
8183 "free chunk is not in free lists"); | |
8184 } | |
8185 | |
8186 | |
8187 if (CMSTraceSweeper) { | |
8188 gclog_or_tty->print_cr(" -- pick up another chunk at 0x%x (%d)", fc, chunkSize); | |
8189 } | |
8190 | |
8191 HeapWord* addr = (HeapWord*) fc; | |
8192 | |
8193 bool coalesce; | |
8194 size_t left = pointer_delta(addr, freeFinger()); | |
8195 size_t right = chunkSize; | |
8196 switch (FLSCoalescePolicy) { | |
8197 // numeric value forms a coalition aggressiveness metric | |
8198 case 0: { // never coalesce | |
8199 coalesce = false; | |
8200 break; | |
8201 } | |
8202 case 1: { // coalesce if left & right chunks on overpopulated lists | |
8203 coalesce = _sp->coalOverPopulated(left) && | |
8204 _sp->coalOverPopulated(right); | |
8205 break; | |
8206 } | |
8207 case 2: { // coalesce if left chunk on overpopulated list (default) | |
8208 coalesce = _sp->coalOverPopulated(left); | |
8209 break; | |
8210 } | |
8211 case 3: { // coalesce if left OR right chunk on overpopulated list | |
8212 coalesce = _sp->coalOverPopulated(left) || | |
8213 _sp->coalOverPopulated(right); | |
8214 break; | |
8215 } | |
8216 case 4: { // always coalesce | |
8217 coalesce = true; | |
8218 break; | |
8219 } | |
8220 default: | |
8221 ShouldNotReachHere(); | |
8222 } | |
8223 | |
8224 // Should the current free range be coalesced? | |
8225 // If the chunk is in a free range and either we decided to coalesce above | |
8226 // or the chunk is near the large block at the end of the heap | |
8227 // (isNearLargestChunk() returns true), then coalesce this chunk. | |
8228 bool doCoalesce = inFreeRange() && | |
8229 (coalesce || _g->isNearLargestChunk((HeapWord*)fc)); | |
8230 if (doCoalesce) { | |
8231 // Coalesce the current free range on the left with the new | |
8232 // chunk on the right. If either is on a free list, | |
8233 // it must be removed from the list and stashed in the closure. | |
8234 if (freeRangeInFreeLists()) { | |
8235 FreeChunk* ffc = (FreeChunk*)freeFinger(); | |
8236 assert(ffc->size() == pointer_delta(addr, freeFinger()), | |
8237 "Size of free range is inconsistent with chunk size."); | |
8238 if (CMSTestInFreeList) { | |
8239 assert(_sp->verifyChunkInFreeLists(ffc), | |
8240 "Chunk is not in free lists"); | |
8241 } | |
8242 _sp->coalDeath(ffc->size()); | |
8243 _sp->removeFreeChunkFromFreeLists(ffc); | |
8244 set_freeRangeInFreeLists(false); | |
8245 } | |
8246 if (fcInFreeLists) { | |
8247 _sp->coalDeath(chunkSize); | |
8248 assert(fc->size() == chunkSize, | |
8249 "The chunk has the wrong size or is not in the free lists"); | |
8250 _sp->removeFreeChunkFromFreeLists(fc); | |
8251 } | |
8252 set_lastFreeRangeCoalesced(true); | |
8253 } else { // not in a free range and/or should not coalesce | |
8254 // Return the current free range and start a new one. | |
8255 if (inFreeRange()) { | |
8256 // In a free range but cannot coalesce with the right hand chunk. | |
8257 // Put the current free range into the free lists. | |
8258 flushCurFreeChunk(freeFinger(), | |
8259 pointer_delta(addr, freeFinger())); | |
8260 } | |
8261 // Set up for new free range. Pass along whether the right hand | |
8262 // chunk is in the free lists. | |
8263 initialize_free_range((HeapWord*)fc, fcInFreeLists); | |
8264 } | |
8265 } | |
8266 void SweepClosure::flushCurFreeChunk(HeapWord* chunk, size_t size) { | |
8267 assert(inFreeRange(), "Should only be called if currently in a free range."); | |
8268 assert(size > 0, | |
8269 "A zero sized chunk cannot be added to the free lists."); | |
8270 if (!freeRangeInFreeLists()) { | |
8271 if(CMSTestInFreeList) { | |
8272 FreeChunk* fc = (FreeChunk*) chunk; | |
8273 fc->setSize(size); | |
8274 assert(!_sp->verifyChunkInFreeLists(fc), | |
8275 "chunk should not be in free lists yet"); | |
8276 } | |
8277 if (CMSTraceSweeper) { | |
8278 gclog_or_tty->print_cr(" -- add free block 0x%x (%d) to free lists", | |
8279 chunk, size); | |
8280 } | |
8281 // A new free range is going to be starting. The current | |
8282 // free range has not been added to the free lists yet or | |
8283 // was removed so add it back. | |
8284 // If the current free range was coalesced, then the death | |
8285 // of the free range was recorded. Record a birth now. | |
8286 if (lastFreeRangeCoalesced()) { | |
8287 _sp->coalBirth(size); | |
8288 } | |
8289 _sp->addChunkAndRepairOffsetTable(chunk, size, | |
8290 lastFreeRangeCoalesced()); | |
8291 } | |
8292 set_inFreeRange(false); | |
8293 set_freeRangeInFreeLists(false); | |
8294 } | |
8295 | |
8296 // We take a break if we've been at this for a while, | |
8297 // so as to avoid monopolizing the locks involved. | |
8298 void SweepClosure::do_yield_work(HeapWord* addr) { | |
8299 // Return current free chunk being used for coalescing (if any) | |
8300 // to the appropriate freelist. After yielding, the next | |
8301 // free block encountered will start a coalescing range of | |
8302 // free blocks. If the next free block is adjacent to the | |
8303 // chunk just flushed, they will need to wait for the next | |
8304 // sweep to be coalesced. | |
8305 if (inFreeRange()) { | |
8306 flushCurFreeChunk(freeFinger(), pointer_delta(addr, freeFinger())); | |
8307 } | |
8308 | |
8309 // First give up the locks, then yield, then re-lock. | |
8310 // We should probably use a constructor/destructor idiom to | |
8311 // do this unlock/lock or modify the MutexUnlocker class to | |
8312 // serve our purpose. XXX | |
8313 assert_lock_strong(_bitMap->lock()); | |
8314 assert_lock_strong(_freelistLock); | |
8315 assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
8316 "CMS thread should hold CMS token"); | |
8317 _bitMap->lock()->unlock(); | |
8318 _freelistLock->unlock(); | |
8319 ConcurrentMarkSweepThread::desynchronize(true); | |
8320 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
8321 _collector->stopTimer(); | |
8322 GCPauseTimer p(_collector->size_policy()->concurrent_timer_ptr()); | |
8323 if (PrintCMSStatistics != 0) { | |
8324 _collector->incrementYields(); | |
8325 } | |
8326 _collector->icms_wait(); | |
8327 | |
8328 // See the comment in coordinator_yield() | |
8329 for (unsigned i = 0; i < CMSYieldSleepCount && | |
8330 ConcurrentMarkSweepThread::should_yield() && | |
8331 !CMSCollector::foregroundGCIsActive(); ++i) { | |
8332 os::sleep(Thread::current(), 1, false); | |
8333 ConcurrentMarkSweepThread::acknowledge_yield_request(); | |
8334 } | |
8335 | |
8336 ConcurrentMarkSweepThread::synchronize(true); | |
8337 _freelistLock->lock(); | |
8338 _bitMap->lock()->lock_without_safepoint_check(); | |
8339 _collector->startTimer(); | |
8340 } | |
8341 | |
8342 #ifndef PRODUCT | |
8343 // This is actually very useful in a product build if it can | |
8344 // be called from the debugger. Compile it into the product | |
8345 // as needed. | |
8346 bool debug_verifyChunkInFreeLists(FreeChunk* fc) { | |
8347 return debug_cms_space->verifyChunkInFreeLists(fc); | |
8348 } | |
8349 | |
8350 void SweepClosure::record_free_block_coalesced(FreeChunk* fc) const { | |
8351 if (CMSTraceSweeper) { | |
8352 gclog_or_tty->print("Sweep:coal_free_blk 0x%x (%d)\n", fc, fc->size()); | |
8353 } | |
8354 } | |
8355 #endif | |
8356 | |
8357 // CMSIsAliveClosure | |
8358 bool CMSIsAliveClosure::do_object_b(oop obj) { | |
8359 HeapWord* addr = (HeapWord*)obj; | |
8360 return addr != NULL && | |
8361 (!_span.contains(addr) || _bit_map->isMarked(addr)); | |
8362 } | |
8363 | |
935 | 8364 CMSKeepAliveClosure::CMSKeepAliveClosure( CMSCollector* collector, |
8365 MemRegion span, | |
8366 CMSBitMap* bit_map, CMSMarkStack* mark_stack, | |
8367 CMSMarkStack* revisit_stack, bool cpc): | |
8368 KlassRememberingOopClosure(collector, NULL, revisit_stack), | |
8369 _span(span), | |
8370 _bit_map(bit_map), | |
8371 _mark_stack(mark_stack), | |
8372 _concurrent_precleaning(cpc) { | |
8373 assert(!_span.is_empty(), "Empty span could spell trouble"); | |
8374 } | |
8375 | |
8376 | |
0 | 8377 // CMSKeepAliveClosure: the serial version |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
8378 void CMSKeepAliveClosure::do_oop(oop obj) { |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
8379 HeapWord* addr = (HeapWord*)obj; |
0 | 8380 if (_span.contains(addr) && |
8381 !_bit_map->isMarked(addr)) { | |
8382 _bit_map->mark(addr); | |
8383 bool simulate_overflow = false; | |
8384 NOT_PRODUCT( | |
8385 if (CMSMarkStackOverflowALot && | |
8386 _collector->simulate_overflow()) { | |
8387 // simulate a stack overflow | |
8388 simulate_overflow = true; | |
8389 } | |
8390 ) | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
8391 if (simulate_overflow || !_mark_stack->push(obj)) { |
452
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
8392 if (_concurrent_precleaning) { |
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
8393 // We dirty the overflown object and let the remark |
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
8394 // phase deal with it. |
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
8395 assert(_collector->overflow_list_is_empty(), "Error"); |
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
8396 // In the case of object arrays, we need to dirty all of |
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
8397 // the cards that the object spans. No locking or atomics |
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
8398 // are needed since no one else can be mutating the mod union |
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
8399 // table. |
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
8400 if (obj->is_objArray()) { |
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
8401 size_t sz = obj->size(); |
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
8402 HeapWord* end_card_addr = |
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
8403 (HeapWord*)round_to((intptr_t)(addr+sz), CardTableModRefBS::card_size); |
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
8404 MemRegion redirty_range = MemRegion(addr, end_card_addr); |
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
8405 assert(!redirty_range.is_empty(), "Arithmetical tautology"); |
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
8406 _collector->_modUnionTable.mark_range(redirty_range); |
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
8407 } else { |
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
8408 _collector->_modUnionTable.mark(addr); |
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
8409 } |
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
8410 _collector->_ser_kac_preclean_ovflw++; |
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
8411 } else { |
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
8412 _collector->push_on_overflow_list(obj); |
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
8413 _collector->_ser_kac_ovflw++; |
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
8414 } |
0 | 8415 } |
8416 } | |
8417 } | |
8418 | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
8419 void CMSKeepAliveClosure::do_oop(oop* p) { CMSKeepAliveClosure::do_oop_work(p); } |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
8420 void CMSKeepAliveClosure::do_oop(narrowOop* p) { CMSKeepAliveClosure::do_oop_work(p); } |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
8421 |
0 | 8422 // CMSParKeepAliveClosure: a parallel version of the above. |
8423 // The work queues are private to each closure (thread), | |
8424 // but (may be) available for stealing by other threads. | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
8425 void CMSParKeepAliveClosure::do_oop(oop obj) { |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
8426 HeapWord* addr = (HeapWord*)obj; |
0 | 8427 if (_span.contains(addr) && |
8428 !_bit_map->isMarked(addr)) { | |
8429 // In general, during recursive tracing, several threads | |
8430 // may be concurrently getting here; the first one to | |
8431 // "tag" it, claims it. | |
8432 if (_bit_map->par_mark(addr)) { | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
8433 bool res = _work_queue->push(obj); |
0 | 8434 assert(res, "Low water mark should be much less than capacity"); |
8435 // Do a recursive trim in the hope that this will keep | |
8436 // stack usage lower, but leave some oops for potential stealers | |
8437 trim_queue(_low_water_mark); | |
8438 } // Else, another thread got there first | |
8439 } | |
8440 } | |
8441 | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
8442 void CMSParKeepAliveClosure::do_oop(oop* p) { CMSParKeepAliveClosure::do_oop_work(p); } |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
8443 void CMSParKeepAliveClosure::do_oop(narrowOop* p) { CMSParKeepAliveClosure::do_oop_work(p); } |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
8444 |
0 | 8445 void CMSParKeepAliveClosure::trim_queue(uint max) { |
8446 while (_work_queue->size() > max) { | |
8447 oop new_oop; | |
8448 if (_work_queue->pop_local(new_oop)) { | |
8449 assert(new_oop != NULL && new_oop->is_oop(), "Expected an oop"); | |
8450 assert(_bit_map->isMarked((HeapWord*)new_oop), | |
8451 "no white objects on this stack!"); | |
8452 assert(_span.contains((HeapWord*)new_oop), "Out of bounds oop"); | |
8453 // iterate over the oops in this oop, marking and pushing | |
8454 // the ones in CMS heap (i.e. in _span). | |
8455 new_oop->oop_iterate(&_mark_and_push); | |
8456 } | |
8457 } | |
8458 } | |
8459 | |
935 | 8460 CMSInnerParMarkAndPushClosure::CMSInnerParMarkAndPushClosure( |
8461 CMSCollector* collector, | |
8462 MemRegion span, CMSBitMap* bit_map, | |
8463 CMSMarkStack* revisit_stack, | |
8464 OopTaskQueue* work_queue): | |
8465 Par_KlassRememberingOopClosure(collector, NULL, revisit_stack), | |
8466 _span(span), | |
8467 _bit_map(bit_map), | |
8468 _work_queue(work_queue) { } | |
8469 | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
8470 void CMSInnerParMarkAndPushClosure::do_oop(oop obj) { |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
8471 HeapWord* addr = (HeapWord*)obj; |
0 | 8472 if (_span.contains(addr) && |
8473 !_bit_map->isMarked(addr)) { | |
8474 if (_bit_map->par_mark(addr)) { | |
8475 bool simulate_overflow = false; | |
8476 NOT_PRODUCT( | |
8477 if (CMSMarkStackOverflowALot && | |
8478 _collector->par_simulate_overflow()) { | |
8479 // simulate a stack overflow | |
8480 simulate_overflow = true; | |
8481 } | |
8482 ) | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
8483 if (simulate_overflow || !_work_queue->push(obj)) { |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
8484 _collector->par_push_on_overflow_list(obj); |
0 | 8485 _collector->_par_kac_ovflw++; |
8486 } | |
8487 } // Else another thread got there already | |
8488 } | |
8489 } | |
8490 | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
8491 void CMSInnerParMarkAndPushClosure::do_oop(oop* p) { CMSInnerParMarkAndPushClosure::do_oop_work(p); } |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
8492 void CMSInnerParMarkAndPushClosure::do_oop(narrowOop* p) { CMSInnerParMarkAndPushClosure::do_oop_work(p); } |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
8493 |
0 | 8494 ////////////////////////////////////////////////////////////////// |
8495 // CMSExpansionCause ///////////////////////////// | |
8496 ////////////////////////////////////////////////////////////////// | |
8497 const char* CMSExpansionCause::to_string(CMSExpansionCause::Cause cause) { | |
8498 switch (cause) { | |
8499 case _no_expansion: | |
8500 return "No expansion"; | |
8501 case _satisfy_free_ratio: | |
8502 return "Free ratio"; | |
8503 case _satisfy_promotion: | |
8504 return "Satisfy promotion"; | |
8505 case _satisfy_allocation: | |
8506 return "allocation"; | |
8507 case _allocate_par_lab: | |
8508 return "Par LAB"; | |
8509 case _allocate_par_spooling_space: | |
8510 return "Par Spooling Space"; | |
8511 case _adaptive_size_policy: | |
8512 return "Ergonomics"; | |
8513 default: | |
8514 return "unknown"; | |
8515 } | |
8516 } | |
8517 | |
8518 void CMSDrainMarkingStackClosure::do_void() { | |
8519 // the max number to take from overflow list at a time | |
8520 const size_t num = _mark_stack->capacity()/4; | |
452
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
8521 assert(!_concurrent_precleaning || _collector->overflow_list_is_empty(), |
00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
ysr
parents:
360
diff
changeset
|
8522 "Overflow list should be NULL during concurrent phases"); |
0 | 8523 while (!_mark_stack->isEmpty() || |
8524 // if stack is empty, check the overflow list | |
8525 _collector->take_from_overflow_list(num, _mark_stack)) { | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
8526 oop obj = _mark_stack->pop(); |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
8527 HeapWord* addr = (HeapWord*)obj; |
0 | 8528 assert(_span.contains(addr), "Should be within span"); |
8529 assert(_bit_map->isMarked(addr), "Should be marked"); | |
113
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
8530 assert(obj->is_oop(), "Should be an oop"); |
ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
94
diff
changeset
|
8531 obj->oop_iterate(_keep_alive); |
0 | 8532 } |
8533 } | |
8534 | |
8535 void CMSParDrainMarkingStackClosure::do_void() { | |
8536 // drain queue | |
8537 trim_queue(0); | |
8538 } | |
8539 | |
8540 // Trim our work_queue so its length is below max at return | |
8541 void CMSParDrainMarkingStackClosure::trim_queue(uint max) { | |
8542 while (_work_queue->size() > max) { | |
8543 oop new_oop; | |
8544 if (_work_queue->pop_local(new_oop)) { | |
8545 assert(new_oop->is_oop(), "Expected an oop"); | |
8546 assert(_bit_map->isMarked((HeapWord*)new_oop), | |
8547 "no white objects on this stack!"); | |
8548 assert(_span.contains((HeapWord*)new_oop), "Out of bounds oop"); | |
8549 // iterate over the oops in this oop, marking and pushing | |
8550 // the ones in CMS heap (i.e. in _span). | |
8551 new_oop->oop_iterate(&_mark_and_push); | |
8552 } | |
8553 } | |
8554 } | |
8555 | |
8556 //////////////////////////////////////////////////////////////////// | |
8557 // Support for Marking Stack Overflow list handling and related code | |
8558 //////////////////////////////////////////////////////////////////// | |
8559 // Much of the following code is similar in shape and spirit to the | |
8560 // code used in ParNewGC. We should try and share that code | |
8561 // as much as possible in the future. | |
8562 | |
8563 #ifndef PRODUCT | |
8564 // Debugging support for CMSStackOverflowALot | |
8565 | |
8566 // It's OK to call this multi-threaded; the worst thing | |
8567 // that can happen is that we'll get a bunch of closely | |
8568 // spaced simulated oveflows, but that's OK, in fact | |
8569 // probably good as it would exercise the overflow code | |
8570 // under contention. | |
8571 bool CMSCollector::simulate_overflow() { | |
8572 if (_overflow_counter-- <= 0) { // just being defensive | |
8573 _overflow_counter = CMSMarkStackOverflowInterval; | |
8574 return true; | |
8575 } else { | |
8576 return false; | |
8577 } | |
8578 } | |
8579 | |
8580 bool CMSCollector::par_simulate_overflow() { | |
8581 return simulate_overflow(); | |
8582 } | |
8583 #endif | |
8584 | |
8585 // Single-threaded | |
8586 bool CMSCollector::take_from_overflow_list(size_t num, CMSMarkStack* stack) { | |
8587 assert(stack->isEmpty(), "Expected precondition"); | |
8588 assert(stack->capacity() > num, "Shouldn't bite more than can chew"); | |
8589 size_t i = num; | |
8590 oop cur = _overflow_list; | |
8591 const markOop proto = markOopDesc::prototype(); | |
534 | 8592 NOT_PRODUCT(ssize_t n = 0;) |
0 | 8593 for (oop next; i > 0 && cur != NULL; cur = next, i--) { |
8594 next = oop(cur->mark()); | |
8595 cur->set_mark(proto); // until proven otherwise | |
8596 assert(cur->is_oop(), "Should be an oop"); | |
8597 bool res = stack->push(cur); | |
8598 assert(res, "Bit off more than can chew?"); | |
8599 NOT_PRODUCT(n++;) | |
8600 } | |
8601 _overflow_list = cur; | |
8602 #ifndef PRODUCT | |
8603 assert(_num_par_pushes >= n, "Too many pops?"); | |
8604 _num_par_pushes -=n; | |
8605 #endif | |
8606 return !stack->isEmpty(); | |
8607 } | |
8608 | |
534 | 8609 #define BUSY (oop(0x1aff1aff)) |
8610 // (MT-safe) Get a prefix of at most "num" from the list. | |
8611 // The overflow list is chained through the mark word of | |
8612 // each object in the list. We fetch the entire list, | |
8613 // break off a prefix of the right size and return the | |
8614 // remainder. If other threads try to take objects from | |
8615 // the overflow list at that time, they will wait for | |
8616 // some time to see if data becomes available. If (and | |
8617 // only if) another thread places one or more object(s) | |
8618 // on the global list before we have returned the suffix | |
8619 // to the global list, we will walk down our local list | |
8620 // to find its end and append the global list to | |
8621 // our suffix before returning it. This suffix walk can | |
8622 // prove to be expensive (quadratic in the amount of traffic) | |
8623 // when there are many objects in the overflow list and | |
8624 // there is much producer-consumer contention on the list. | |
8625 // *NOTE*: The overflow list manipulation code here and | |
8626 // in ParNewGeneration:: are very similar in shape, | |
8627 // except that in the ParNew case we use the old (from/eden) | |
8628 // copy of the object to thread the list via its klass word. | |
8629 // Because of the common code, if you make any changes in | |
8630 // the code below, please check the ParNew version to see if | |
8631 // similar changes might be needed. | |
8632 // CR 6797058 has been filed to consolidate the common code. | |
0 | 8633 bool CMSCollector::par_take_from_overflow_list(size_t num, |
8634 OopTaskQueue* work_q) { | |
534 | 8635 assert(work_q->size() == 0, "First empty local work queue"); |
0 | 8636 assert(num < work_q->max_elems(), "Can't bite more than we can chew"); |
8637 if (_overflow_list == NULL) { | |
8638 return false; | |
8639 } | |
8640 // Grab the entire list; we'll put back a suffix | |
534 | 8641 oop prefix = (oop)Atomic::xchg_ptr(BUSY, &_overflow_list); |
8642 Thread* tid = Thread::current(); | |
8643 size_t CMSOverflowSpinCount = (size_t)ParallelGCThreads; | |
8644 size_t sleep_time_millis = MAX2((size_t)1, num/100); | |
8645 // If the list is busy, we spin for a short while, | |
8646 // sleeping between attempts to get the list. | |
8647 for (size_t spin = 0; prefix == BUSY && spin < CMSOverflowSpinCount; spin++) { | |
8648 os::sleep(tid, sleep_time_millis, false); | |
8649 if (_overflow_list == NULL) { | |
8650 // Nothing left to take | |
8651 return false; | |
8652 } else if (_overflow_list != BUSY) { | |
8653 // Try and grab the prefix | |
8654 prefix = (oop)Atomic::xchg_ptr(BUSY, &_overflow_list); | |
8655 } | |
8656 } | |
8657 // If the list was found to be empty, or we spun long | |
8658 // enough, we give up and return empty-handed. If we leave | |
8659 // the list in the BUSY state below, it must be the case that | |
8660 // some other thread holds the overflow list and will set it | |
8661 // to a non-BUSY state in the future. | |
8662 if (prefix == NULL || prefix == BUSY) { | |
8663 // Nothing to take or waited long enough | |
8664 if (prefix == NULL) { | |
8665 // Write back the NULL in case we overwrote it with BUSY above | |
8666 // and it is still the same value. | |
8667 (void) Atomic::cmpxchg_ptr(NULL, &_overflow_list, BUSY); | |
8668 } | |
8669 return false; | |
8670 } | |
8671 assert(prefix != NULL && prefix != BUSY, "Error"); | |
0 | 8672 size_t i = num; |
8673 oop cur = prefix; | |
534 | 8674 // Walk down the first "num" objects, unless we reach the end. |
0 | 8675 for (; i > 1 && cur->mark() != NULL; cur = oop(cur->mark()), i--); |
534 | 8676 if (cur->mark() == NULL) { |
8677 // We have "num" or fewer elements in the list, so there | |
8678 // is nothing to return to the global list. | |
8679 // Write back the NULL in lieu of the BUSY we wrote | |
8680 // above, if it is still the same value. | |
8681 if (_overflow_list == BUSY) { | |
8682 (void) Atomic::cmpxchg_ptr(NULL, &_overflow_list, BUSY); | |
8683 } | |
8684 } else { | |
8685 // Chop off the suffix and rerturn it to the global list. | |
8686 assert(cur->mark() != BUSY, "Error"); | |
0 | 8687 oop suffix_head = cur->mark(); // suffix will be put back on global list |
8688 cur->set_mark(NULL); // break off suffix | |
534 | 8689 // It's possible that the list is still in the empty(busy) state |
8690 // we left it in a short while ago; in that case we may be | |
8691 // able to place back the suffix without incurring the cost | |
8692 // of a walk down the list. | |
0 | 8693 oop observed_overflow_list = _overflow_list; |
534 | 8694 oop cur_overflow_list = observed_overflow_list; |
8695 bool attached = false; | |
8696 while (observed_overflow_list == BUSY || observed_overflow_list == NULL) { | |
0 | 8697 observed_overflow_list = |
534 | 8698 (oop) Atomic::cmpxchg_ptr(suffix_head, &_overflow_list, cur_overflow_list); |
8699 if (cur_overflow_list == observed_overflow_list) { | |
8700 attached = true; | |
8701 break; | |
8702 } else cur_overflow_list = observed_overflow_list; | |
8703 } | |
8704 if (!attached) { | |
8705 // Too bad, someone else sneaked in (at least) an element; we'll need | |
8706 // to do a splice. Find tail of suffix so we can prepend suffix to global | |
8707 // list. | |
8708 for (cur = suffix_head; cur->mark() != NULL; cur = (oop)(cur->mark())); | |
8709 oop suffix_tail = cur; | |
8710 assert(suffix_tail != NULL && suffix_tail->mark() == NULL, | |
8711 "Tautology"); | |
8712 observed_overflow_list = _overflow_list; | |
8713 do { | |
8714 cur_overflow_list = observed_overflow_list; | |
8715 if (cur_overflow_list != BUSY) { | |
8716 // Do the splice ... | |
8717 suffix_tail->set_mark(markOop(cur_overflow_list)); | |
8718 } else { // cur_overflow_list == BUSY | |
8719 suffix_tail->set_mark(NULL); | |
8720 } | |
8721 // ... and try to place spliced list back on overflow_list ... | |
8722 observed_overflow_list = | |
8723 (oop) Atomic::cmpxchg_ptr(suffix_head, &_overflow_list, cur_overflow_list); | |
8724 } while (cur_overflow_list != observed_overflow_list); | |
8725 // ... until we have succeeded in doing so. | |
8726 } | |
0 | 8727 } |
8728 | |
8729 // Push the prefix elements on work_q | |
8730 assert(prefix != NULL, "control point invariant"); | |
8731 const markOop proto = markOopDesc::prototype(); | |
8732 oop next; | |
534 | 8733 NOT_PRODUCT(ssize_t n = 0;) |
0 | 8734 for (cur = prefix; cur != NULL; cur = next) { |
8735 next = oop(cur->mark()); | |
8736 cur->set_mark(proto); // until proven otherwise | |
8737 assert(cur->is_oop(), "Should be an oop"); | |
8738 bool res = work_q->push(cur); | |
8739 assert(res, "Bit off more than we can chew?"); | |
8740 NOT_PRODUCT(n++;) | |
8741 } | |
8742 #ifndef PRODUCT | |
8743 assert(_num_par_pushes >= n, "Too many pops?"); | |
8744 Atomic::add_ptr(-(intptr_t)n, &_num_par_pushes); | |
8745 #endif | |
8746 return true; | |
8747 } | |
8748 | |
8749 // Single-threaded | |
8750 void CMSCollector::push_on_overflow_list(oop p) { | |
8751 NOT_PRODUCT(_num_par_pushes++;) | |
8752 assert(p->is_oop(), "Not an oop"); | |
8753 preserve_mark_if_necessary(p); | |
8754 p->set_mark((markOop)_overflow_list); | |
8755 _overflow_list = p; | |
8756 } | |
8757 | |
8758 // Multi-threaded; use CAS to prepend to overflow list | |
8759 void CMSCollector::par_push_on_overflow_list(oop p) { | |
8760 NOT_PRODUCT(Atomic::inc_ptr(&_num_par_pushes);) | |
8761 assert(p->is_oop(), "Not an oop"); | |
8762 par_preserve_mark_if_necessary(p); | |
8763 oop observed_overflow_list = _overflow_list; | |
8764 oop cur_overflow_list; | |
8765 do { | |
8766 cur_overflow_list = observed_overflow_list; | |
534 | 8767 if (cur_overflow_list != BUSY) { |
8768 p->set_mark(markOop(cur_overflow_list)); | |
8769 } else { | |
8770 p->set_mark(NULL); | |
8771 } | |
0 | 8772 observed_overflow_list = |
8773 (oop) Atomic::cmpxchg_ptr(p, &_overflow_list, cur_overflow_list); | |
8774 } while (cur_overflow_list != observed_overflow_list); | |
8775 } | |
534 | 8776 #undef BUSY |
0 | 8777 |
8778 // Single threaded | |
8779 // General Note on GrowableArray: pushes may silently fail | |
8780 // because we are (temporarily) out of C-heap for expanding | |
8781 // the stack. The problem is quite ubiquitous and affects | |
8782 // a lot of code in the JVM. The prudent thing for GrowableArray | |
8783 // to do (for now) is to exit with an error. However, that may | |
8784 // be too draconian in some cases because the caller may be | |
534 | 8785 // able to recover without much harm. For such cases, we |
0 | 8786 // should probably introduce a "soft_push" method which returns |
8787 // an indication of success or failure with the assumption that | |
8788 // the caller may be able to recover from a failure; code in | |
8789 // the VM can then be changed, incrementally, to deal with such | |
8790 // failures where possible, thus, incrementally hardening the VM | |
8791 // in such low resource situations. | |
8792 void CMSCollector::preserve_mark_work(oop p, markOop m) { | |
8793 if (_preserved_oop_stack == NULL) { | |
8794 assert(_preserved_mark_stack == NULL, | |
8795 "bijection with preserved_oop_stack"); | |
8796 // Allocate the stacks | |
8797 _preserved_oop_stack = new (ResourceObj::C_HEAP) | |
8798 GrowableArray<oop>(PreserveMarkStackSize, true); | |
8799 _preserved_mark_stack = new (ResourceObj::C_HEAP) | |
8800 GrowableArray<markOop>(PreserveMarkStackSize, true); | |
8801 if (_preserved_oop_stack == NULL || _preserved_mark_stack == NULL) { | |
8802 vm_exit_out_of_memory(2* PreserveMarkStackSize * sizeof(oop) /* punt */, | |
8803 "Preserved Mark/Oop Stack for CMS (C-heap)"); | |
8804 } | |
8805 } | |
8806 _preserved_oop_stack->push(p); | |
8807 _preserved_mark_stack->push(m); | |
8808 assert(m == p->mark(), "Mark word changed"); | |
8809 assert(_preserved_oop_stack->length() == _preserved_mark_stack->length(), | |
8810 "bijection"); | |
8811 } | |
8812 | |
8813 // Single threaded | |
8814 void CMSCollector::preserve_mark_if_necessary(oop p) { | |
8815 markOop m = p->mark(); | |
8816 if (m->must_be_preserved(p)) { | |
8817 preserve_mark_work(p, m); | |
8818 } | |
8819 } | |
8820 | |
8821 void CMSCollector::par_preserve_mark_if_necessary(oop p) { | |
8822 markOop m = p->mark(); | |
8823 if (m->must_be_preserved(p)) { | |
8824 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); | |
8825 // Even though we read the mark word without holding | |
8826 // the lock, we are assured that it will not change | |
8827 // because we "own" this oop, so no other thread can | |
8828 // be trying to push it on the overflow list; see | |
8829 // the assertion in preserve_mark_work() that checks | |
8830 // that m == p->mark(). | |
8831 preserve_mark_work(p, m); | |
8832 } | |
8833 } | |
8834 | |
8835 // We should be able to do this multi-threaded, | |
8836 // a chunk of stack being a task (this is | |
8837 // correct because each oop only ever appears | |
8838 // once in the overflow list. However, it's | |
8839 // not very easy to completely overlap this with | |
8840 // other operations, so will generally not be done | |
8841 // until all work's been completed. Because we | |
8842 // expect the preserved oop stack (set) to be small, | |
8843 // it's probably fine to do this single-threaded. | |
8844 // We can explore cleverer concurrent/overlapped/parallel | |
8845 // processing of preserved marks if we feel the | |
8846 // need for this in the future. Stack overflow should | |
8847 // be so rare in practice and, when it happens, its | |
8848 // effect on performance so great that this will | |
8849 // likely just be in the noise anyway. | |
8850 void CMSCollector::restore_preserved_marks_if_any() { | |
8851 if (_preserved_oop_stack == NULL) { | |
8852 assert(_preserved_mark_stack == NULL, | |
8853 "bijection with preserved_oop_stack"); | |
8854 return; | |
8855 } | |
8856 | |
8857 assert(SafepointSynchronize::is_at_safepoint(), | |
8858 "world should be stopped"); | |
8859 assert(Thread::current()->is_ConcurrentGC_thread() || | |
8860 Thread::current()->is_VM_thread(), | |
8861 "should be single-threaded"); | |
8862 | |
8863 int length = _preserved_oop_stack->length(); | |
8864 assert(_preserved_mark_stack->length() == length, "bijection"); | |
8865 for (int i = 0; i < length; i++) { | |
8866 oop p = _preserved_oop_stack->at(i); | |
8867 assert(p->is_oop(), "Should be an oop"); | |
8868 assert(_span.contains(p), "oop should be in _span"); | |
8869 assert(p->mark() == markOopDesc::prototype(), | |
8870 "Set when taken from overflow list"); | |
8871 markOop m = _preserved_mark_stack->at(i); | |
8872 p->set_mark(m); | |
8873 } | |
8874 _preserved_mark_stack->clear(); | |
8875 _preserved_oop_stack->clear(); | |
8876 assert(_preserved_mark_stack->is_empty() && | |
8877 _preserved_oop_stack->is_empty(), | |
8878 "stacks were cleared above"); | |
8879 } | |
8880 | |
8881 #ifndef PRODUCT | |
8882 bool CMSCollector::no_preserved_marks() const { | |
8883 return ( ( _preserved_mark_stack == NULL | |
8884 && _preserved_oop_stack == NULL) | |
8885 || ( _preserved_mark_stack->is_empty() | |
8886 && _preserved_oop_stack->is_empty())); | |
8887 } | |
8888 #endif | |
8889 | |
8890 CMSAdaptiveSizePolicy* ASConcurrentMarkSweepGeneration::cms_size_policy() const | |
8891 { | |
8892 GenCollectedHeap* gch = (GenCollectedHeap*) GenCollectedHeap::heap(); | |
8893 CMSAdaptiveSizePolicy* size_policy = | |
8894 (CMSAdaptiveSizePolicy*) gch->gen_policy()->size_policy(); | |
8895 assert(size_policy->is_gc_cms_adaptive_size_policy(), | |
8896 "Wrong type for size policy"); | |
8897 return size_policy; | |
8898 } | |
8899 | |
8900 void ASConcurrentMarkSweepGeneration::resize(size_t cur_promo_size, | |
8901 size_t desired_promo_size) { | |
8902 if (cur_promo_size < desired_promo_size) { | |
8903 size_t expand_bytes = desired_promo_size - cur_promo_size; | |
8904 if (PrintAdaptiveSizePolicy && Verbose) { | |
8905 gclog_or_tty->print_cr(" ASConcurrentMarkSweepGeneration::resize " | |
8906 "Expanding tenured generation by " SIZE_FORMAT " (bytes)", | |
8907 expand_bytes); | |
8908 } | |
8909 expand(expand_bytes, | |
8910 MinHeapDeltaBytes, | |
8911 CMSExpansionCause::_adaptive_size_policy); | |
8912 } else if (desired_promo_size < cur_promo_size) { | |
8913 size_t shrink_bytes = cur_promo_size - desired_promo_size; | |
8914 if (PrintAdaptiveSizePolicy && Verbose) { | |
8915 gclog_or_tty->print_cr(" ASConcurrentMarkSweepGeneration::resize " | |
8916 "Shrinking tenured generation by " SIZE_FORMAT " (bytes)", | |
8917 shrink_bytes); | |
8918 } | |
8919 shrink(shrink_bytes); | |
8920 } | |
8921 } | |
8922 | |
8923 CMSGCAdaptivePolicyCounters* ASConcurrentMarkSweepGeneration::gc_adaptive_policy_counters() { | |
8924 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
8925 CMSGCAdaptivePolicyCounters* counters = | |
8926 (CMSGCAdaptivePolicyCounters*) gch->collector_policy()->counters(); | |
8927 assert(counters->kind() == GCPolicyCounters::CMSGCAdaptivePolicyCountersKind, | |
8928 "Wrong kind of counters"); | |
8929 return counters; | |
8930 } | |
8931 | |
8932 | |
8933 void ASConcurrentMarkSweepGeneration::update_counters() { | |
8934 if (UsePerfData) { | |
8935 _space_counters->update_all(); | |
8936 _gen_counters->update_all(); | |
8937 CMSGCAdaptivePolicyCounters* counters = gc_adaptive_policy_counters(); | |
8938 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
8939 CMSGCStats* gc_stats_l = (CMSGCStats*) gc_stats(); | |
8940 assert(gc_stats_l->kind() == GCStats::CMSGCStatsKind, | |
8941 "Wrong gc statistics type"); | |
8942 counters->update_counters(gc_stats_l); | |
8943 } | |
8944 } | |
8945 | |
8946 void ASConcurrentMarkSweepGeneration::update_counters(size_t used) { | |
8947 if (UsePerfData) { | |
8948 _space_counters->update_used(used); | |
8949 _space_counters->update_capacity(); | |
8950 _gen_counters->update_all(); | |
8951 | |
8952 CMSGCAdaptivePolicyCounters* counters = gc_adaptive_policy_counters(); | |
8953 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
8954 CMSGCStats* gc_stats_l = (CMSGCStats*) gc_stats(); | |
8955 assert(gc_stats_l->kind() == GCStats::CMSGCStatsKind, | |
8956 "Wrong gc statistics type"); | |
8957 counters->update_counters(gc_stats_l); | |
8958 } | |
8959 } | |
8960 | |
8961 // The desired expansion delta is computed so that: | |
8962 // . desired free percentage or greater is used | |
8963 void ASConcurrentMarkSweepGeneration::compute_new_size() { | |
8964 assert_locked_or_safepoint(Heap_lock); | |
8965 | |
8966 GenCollectedHeap* gch = (GenCollectedHeap*) GenCollectedHeap::heap(); | |
8967 | |
8968 // If incremental collection failed, we just want to expand | |
8969 // to the limit. | |
8970 if (incremental_collection_failed()) { | |
8971 clear_incremental_collection_failed(); | |
8972 grow_to_reserved(); | |
8973 return; | |
8974 } | |
8975 | |
8976 assert(UseAdaptiveSizePolicy, "Should be using adaptive sizing"); | |
8977 | |
8978 assert(gch->kind() == CollectedHeap::GenCollectedHeap, | |
8979 "Wrong type of heap"); | |
8980 int prev_level = level() - 1; | |
8981 assert(prev_level >= 0, "The cms generation is the lowest generation"); | |
8982 Generation* prev_gen = gch->get_gen(prev_level); | |
8983 assert(prev_gen->kind() == Generation::ASParNew, | |
8984 "Wrong type of young generation"); | |
8985 ParNewGeneration* younger_gen = (ParNewGeneration*) prev_gen; | |
8986 size_t cur_eden = younger_gen->eden()->capacity(); | |
8987 CMSAdaptiveSizePolicy* size_policy = cms_size_policy(); | |
8988 size_t cur_promo = free(); | |
8989 size_policy->compute_tenured_generation_free_space(cur_promo, | |
8990 max_available(), | |
8991 cur_eden); | |
8992 resize(cur_promo, size_policy->promo_size()); | |
8993 | |
8994 // Record the new size of the space in the cms generation | |
8995 // that is available for promotions. This is temporary. | |
8996 // It should be the desired promo size. | |
8997 size_policy->avg_cms_promo()->sample(free()); | |
8998 size_policy->avg_old_live()->sample(used()); | |
8999 | |
9000 if (UsePerfData) { | |
9001 CMSGCAdaptivePolicyCounters* counters = gc_adaptive_policy_counters(); | |
9002 counters->update_cms_capacity_counter(capacity()); | |
9003 } | |
9004 } | |
9005 | |
9006 void ASConcurrentMarkSweepGeneration::shrink_by(size_t desired_bytes) { | |
9007 assert_locked_or_safepoint(Heap_lock); | |
9008 assert_lock_strong(freelistLock()); | |
9009 HeapWord* old_end = _cmsSpace->end(); | |
9010 HeapWord* unallocated_start = _cmsSpace->unallocated_block(); | |
9011 assert(old_end >= unallocated_start, "Miscalculation of unallocated_start"); | |
9012 FreeChunk* chunk_at_end = find_chunk_at_end(); | |
9013 if (chunk_at_end == NULL) { | |
9014 // No room to shrink | |
9015 if (PrintGCDetails && Verbose) { | |
9016 gclog_or_tty->print_cr("No room to shrink: old_end " | |
9017 PTR_FORMAT " unallocated_start " PTR_FORMAT | |
9018 " chunk_at_end " PTR_FORMAT, | |
9019 old_end, unallocated_start, chunk_at_end); | |
9020 } | |
9021 return; | |
9022 } else { | |
9023 | |
9024 // Find the chunk at the end of the space and determine | |
9025 // how much it can be shrunk. | |
9026 size_t shrinkable_size_in_bytes = chunk_at_end->size(); | |
9027 size_t aligned_shrinkable_size_in_bytes = | |
9028 align_size_down(shrinkable_size_in_bytes, os::vm_page_size()); | |
9029 assert(unallocated_start <= chunk_at_end->end(), | |
9030 "Inconsistent chunk at end of space"); | |
9031 size_t bytes = MIN2(desired_bytes, aligned_shrinkable_size_in_bytes); | |
9032 size_t word_size_before = heap_word_size(_virtual_space.committed_size()); | |
9033 | |
9034 // Shrink the underlying space | |
9035 _virtual_space.shrink_by(bytes); | |
9036 if (PrintGCDetails && Verbose) { | |
9037 gclog_or_tty->print_cr("ConcurrentMarkSweepGeneration::shrink_by:" | |
9038 " desired_bytes " SIZE_FORMAT | |
9039 " shrinkable_size_in_bytes " SIZE_FORMAT | |
9040 " aligned_shrinkable_size_in_bytes " SIZE_FORMAT | |
9041 " bytes " SIZE_FORMAT, | |
9042 desired_bytes, shrinkable_size_in_bytes, | |
9043 aligned_shrinkable_size_in_bytes, bytes); | |
9044 gclog_or_tty->print_cr(" old_end " SIZE_FORMAT | |
9045 " unallocated_start " SIZE_FORMAT, | |
9046 old_end, unallocated_start); | |
9047 } | |
9048 | |
9049 // If the space did shrink (shrinking is not guaranteed), | |
9050 // shrink the chunk at the end by the appropriate amount. | |
9051 if (((HeapWord*)_virtual_space.high()) < old_end) { | |
9052 size_t new_word_size = | |
9053 heap_word_size(_virtual_space.committed_size()); | |
9054 | |
9055 // Have to remove the chunk from the dictionary because it is changing | |
9056 // size and might be someplace elsewhere in the dictionary. | |
9057 | |
9058 // Get the chunk at end, shrink it, and put it | |
9059 // back. | |
9060 _cmsSpace->removeChunkFromDictionary(chunk_at_end); | |
9061 size_t word_size_change = word_size_before - new_word_size; | |
9062 size_t chunk_at_end_old_size = chunk_at_end->size(); | |
9063 assert(chunk_at_end_old_size >= word_size_change, | |
9064 "Shrink is too large"); | |
9065 chunk_at_end->setSize(chunk_at_end_old_size - | |
9066 word_size_change); | |
9067 _cmsSpace->freed((HeapWord*) chunk_at_end->end(), | |
9068 word_size_change); | |
9069 | |
9070 _cmsSpace->returnChunkToDictionary(chunk_at_end); | |
9071 | |
9072 MemRegion mr(_cmsSpace->bottom(), new_word_size); | |
9073 _bts->resize(new_word_size); // resize the block offset shared array | |
9074 Universe::heap()->barrier_set()->resize_covered_region(mr); | |
9075 _cmsSpace->assert_locked(); | |
9076 _cmsSpace->set_end((HeapWord*)_virtual_space.high()); | |
9077 | |
9078 NOT_PRODUCT(_cmsSpace->dictionary()->verify()); | |
9079 | |
9080 // update the space and generation capacity counters | |
9081 if (UsePerfData) { | |
9082 _space_counters->update_capacity(); | |
9083 _gen_counters->update_all(); | |
9084 } | |
9085 | |
9086 if (Verbose && PrintGCDetails) { | |
9087 size_t new_mem_size = _virtual_space.committed_size(); | |
9088 size_t old_mem_size = new_mem_size + bytes; | |
9089 gclog_or_tty->print_cr("Shrinking %s from %ldK by %ldK to %ldK", | |
9090 name(), old_mem_size/K, bytes/K, new_mem_size/K); | |
9091 } | |
9092 } | |
9093 | |
9094 assert(_cmsSpace->unallocated_block() <= _cmsSpace->end(), | |
9095 "Inconsistency at end of space"); | |
9096 assert(chunk_at_end->end() == _cmsSpace->end(), | |
9097 "Shrinking is inconsistent"); | |
9098 return; | |
9099 } | |
9100 } | |
9101 | |
9102 // Transfer some number of overflown objects to usual marking | |
9103 // stack. Return true if some objects were transferred. | |
9104 bool MarkRefsIntoAndScanClosure::take_from_overflow_list() { | |
679
cea947c8a988
6819891: ParNew: Fix work queue overflow code to deal correctly with +UseCompressedOops
ysr
parents:
628
diff
changeset
|
9105 size_t num = MIN2((size_t)(_mark_stack->capacity() - _mark_stack->length())/4, |
0 | 9106 (size_t)ParGCDesiredObjsFromOverflowList); |
9107 | |
9108 bool res = _collector->take_from_overflow_list(num, _mark_stack); | |
9109 assert(_collector->overflow_list_is_empty() || res, | |
9110 "If list is not empty, we should have taken something"); | |
9111 assert(!res || !_mark_stack->isEmpty(), | |
9112 "If we took something, it should now be on our stack"); | |
9113 return res; | |
9114 } | |
9115 | |
9116 size_t MarkDeadObjectsClosure::do_blk(HeapWord* addr) { | |
9117 size_t res = _sp->block_size_no_stall(addr, _collector); | |
9118 assert(res != 0, "Should always be able to compute a size"); | |
9119 if (_sp->block_is_obj(addr)) { | |
9120 if (_live_bit_map->isMarked(addr)) { | |
9121 // It can't have been dead in a previous cycle | |
9122 guarantee(!_dead_bit_map->isMarked(addr), "No resurrection!"); | |
9123 } else { | |
9124 _dead_bit_map->mark(addr); // mark the dead object | |
9125 } | |
9126 } | |
9127 return res; | |
9128 } |