Mercurial > hg > truffle
annotate src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.hpp @ 795:215f81b4d9b3
6841831: G1: assert(contains_reference(from),"We just added it!") fires
Summary: During parallel rset updating we have to make sure that the worker ids of the refinement threads do not intersect with the worker ids that can be claimed by the mutator threads.
Reviewed-by: tonyp
author | iveresov |
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date | Mon, 18 May 2009 11:52:46 -0700 |
parents | 0fbdb4381b99 |
children | fe1574da39fc |
rev | line source |
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0 | 1 /* |
579 | 2 * Copyright 2001-2009 Sun Microsystems, Inc. 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 * | |
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, | |
20 * CA 95054 USA or visit www.sun.com if you need additional information or | |
21 * have any questions. | |
22 * | |
23 */ | |
24 | |
25 // ConcurrentMarkSweepGeneration is in support of a concurrent | |
26 // mark-sweep old generation in the Detlefs-Printezis--Boehm-Demers-Schenker | |
27 // style. We assume, for now, that this generation is always the | |
28 // seniormost generation (modulo the PermGeneration), and for simplicity | |
29 // in the first implementation, that this generation is a single compactible | |
30 // space. Neither of these restrictions appears essential, and will be | |
31 // relaxed in the future when more time is available to implement the | |
32 // greater generality (and there's a need for it). | |
33 // | |
34 // Concurrent mode failures are currently handled by | |
35 // means of a sliding mark-compact. | |
36 | |
37 class CMSAdaptiveSizePolicy; | |
38 class CMSConcMarkingTask; | |
39 class CMSGCAdaptivePolicyCounters; | |
40 class ConcurrentMarkSweepGeneration; | |
41 class ConcurrentMarkSweepPolicy; | |
42 class ConcurrentMarkSweepThread; | |
43 class CompactibleFreeListSpace; | |
44 class FreeChunk; | |
45 class PromotionInfo; | |
46 class ScanMarkedObjectsAgainCarefullyClosure; | |
47 | |
48 // A generic CMS bit map. It's the basis for both the CMS marking bit map | |
49 // as well as for the mod union table (in each case only a subset of the | |
50 // methods are used). This is essentially a wrapper around the BitMap class, | |
51 // with one bit per (1<<_shifter) HeapWords. (i.e. for the marking bit map, | |
52 // we have _shifter == 0. and for the mod union table we have | |
53 // shifter == CardTableModRefBS::card_shift - LogHeapWordSize.) | |
54 // XXX 64-bit issues in BitMap? | |
55 class CMSBitMap VALUE_OBJ_CLASS_SPEC { | |
56 friend class VMStructs; | |
57 | |
58 HeapWord* _bmStartWord; // base address of range covered by map | |
59 size_t _bmWordSize; // map size (in #HeapWords covered) | |
60 const int _shifter; // shifts to convert HeapWord to bit position | |
61 VirtualSpace _virtual_space; // underlying the bit map | |
62 BitMap _bm; // the bit map itself | |
63 public: | |
64 Mutex* const _lock; // mutex protecting _bm; | |
65 | |
66 public: | |
67 // constructor | |
68 CMSBitMap(int shifter, int mutex_rank, const char* mutex_name); | |
69 | |
70 // allocates the actual storage for the map | |
71 bool allocate(MemRegion mr); | |
72 // field getter | |
73 Mutex* lock() const { return _lock; } | |
74 // locking verifier convenience function | |
75 void assert_locked() const PRODUCT_RETURN; | |
76 | |
77 // inquiries | |
78 HeapWord* startWord() const { return _bmStartWord; } | |
79 size_t sizeInWords() const { return _bmWordSize; } | |
80 size_t sizeInBits() const { return _bm.size(); } | |
81 // the following is one past the last word in space | |
82 HeapWord* endWord() const { return _bmStartWord + _bmWordSize; } | |
83 | |
84 // reading marks | |
85 bool isMarked(HeapWord* addr) const; | |
86 bool par_isMarked(HeapWord* addr) const; // do not lock checks | |
87 bool isUnmarked(HeapWord* addr) const; | |
88 bool isAllClear() const; | |
89 | |
90 // writing marks | |
91 void mark(HeapWord* addr); | |
92 // For marking by parallel GC threads; | |
93 // returns true if we did, false if another thread did | |
94 bool par_mark(HeapWord* addr); | |
95 | |
96 void mark_range(MemRegion mr); | |
97 void par_mark_range(MemRegion mr); | |
98 void mark_large_range(MemRegion mr); | |
99 void par_mark_large_range(MemRegion mr); | |
100 void par_clear(HeapWord* addr); // For unmarking by parallel GC threads. | |
101 void clear_range(MemRegion mr); | |
102 void par_clear_range(MemRegion mr); | |
103 void clear_large_range(MemRegion mr); | |
104 void par_clear_large_range(MemRegion mr); | |
105 void clear_all(); | |
106 void clear_all_incrementally(); // Not yet implemented!! | |
107 | |
108 NOT_PRODUCT( | |
109 // checks the memory region for validity | |
110 void region_invariant(MemRegion mr); | |
111 ) | |
112 | |
113 // iteration | |
114 void iterate(BitMapClosure* cl) { | |
115 _bm.iterate(cl); | |
116 } | |
117 void iterate(BitMapClosure* cl, HeapWord* left, HeapWord* right); | |
118 void dirty_range_iterate_clear(MemRegionClosure* cl); | |
119 void dirty_range_iterate_clear(MemRegion mr, MemRegionClosure* cl); | |
120 | |
121 // auxiliary support for iteration | |
122 HeapWord* getNextMarkedWordAddress(HeapWord* addr) const; | |
123 HeapWord* getNextMarkedWordAddress(HeapWord* start_addr, | |
124 HeapWord* end_addr) const; | |
125 HeapWord* getNextUnmarkedWordAddress(HeapWord* addr) const; | |
126 HeapWord* getNextUnmarkedWordAddress(HeapWord* start_addr, | |
127 HeapWord* end_addr) const; | |
128 MemRegion getAndClearMarkedRegion(HeapWord* addr); | |
129 MemRegion getAndClearMarkedRegion(HeapWord* start_addr, | |
130 HeapWord* end_addr); | |
131 | |
132 // conversion utilities | |
133 HeapWord* offsetToHeapWord(size_t offset) const; | |
134 size_t heapWordToOffset(HeapWord* addr) const; | |
135 size_t heapWordDiffToOffsetDiff(size_t diff) const; | |
136 | |
137 // debugging | |
138 // is this address range covered by the bit-map? | |
139 NOT_PRODUCT( | |
140 bool covers(MemRegion mr) const; | |
141 bool covers(HeapWord* start, size_t size = 0) const; | |
142 ) | |
143 void verifyNoOneBitsInRange(HeapWord* left, HeapWord* right) PRODUCT_RETURN; | |
144 }; | |
145 | |
146 // Represents a marking stack used by the CMS collector. | |
147 // Ideally this should be GrowableArray<> just like MSC's marking stack(s). | |
148 class CMSMarkStack: public CHeapObj { | |
149 // | |
150 friend class CMSCollector; // to get at expasion stats further below | |
151 // | |
152 | |
153 VirtualSpace _virtual_space; // space for the stack | |
154 oop* _base; // bottom of stack | |
155 size_t _index; // one more than last occupied index | |
156 size_t _capacity; // max #elements | |
157 Mutex _par_lock; // an advisory lock used in case of parallel access | |
158 NOT_PRODUCT(size_t _max_depth;) // max depth plumbed during run | |
159 | |
160 protected: | |
161 size_t _hit_limit; // we hit max stack size limit | |
162 size_t _failed_double; // we failed expansion before hitting limit | |
163 | |
164 public: | |
165 CMSMarkStack(): | |
166 _par_lock(Mutex::event, "CMSMarkStack._par_lock", true), | |
167 _hit_limit(0), | |
168 _failed_double(0) {} | |
169 | |
170 bool allocate(size_t size); | |
171 | |
172 size_t capacity() const { return _capacity; } | |
173 | |
174 oop pop() { | |
175 if (!isEmpty()) { | |
176 return _base[--_index] ; | |
177 } | |
178 return NULL; | |
179 } | |
180 | |
181 bool push(oop ptr) { | |
182 if (isFull()) { | |
183 return false; | |
184 } else { | |
185 _base[_index++] = ptr; | |
186 NOT_PRODUCT(_max_depth = MAX2(_max_depth, _index)); | |
187 return true; | |
188 } | |
189 } | |
190 | |
191 bool isEmpty() const { return _index == 0; } | |
192 bool isFull() const { | |
193 assert(_index <= _capacity, "buffer overflow"); | |
194 return _index == _capacity; | |
195 } | |
196 | |
197 size_t length() { return _index; } | |
198 | |
199 // "Parallel versions" of some of the above | |
200 oop par_pop() { | |
201 // lock and pop | |
202 MutexLockerEx x(&_par_lock, Mutex::_no_safepoint_check_flag); | |
203 return pop(); | |
204 } | |
205 | |
206 bool par_push(oop ptr) { | |
207 // lock and push | |
208 MutexLockerEx x(&_par_lock, Mutex::_no_safepoint_check_flag); | |
209 return push(ptr); | |
210 } | |
211 | |
212 // Forcibly reset the stack, losing all of its contents. | |
213 void reset() { | |
214 _index = 0; | |
215 } | |
216 | |
217 // Expand the stack, typically in response to an overflow condition | |
218 void expand(); | |
219 | |
220 // Compute the least valued stack element. | |
221 oop least_value(HeapWord* low) { | |
222 oop least = (oop)low; | |
223 for (size_t i = 0; i < _index; i++) { | |
224 least = MIN2(least, _base[i]); | |
225 } | |
226 return least; | |
227 } | |
228 | |
229 // Exposed here to allow stack expansion in || case | |
230 Mutex* par_lock() { return &_par_lock; } | |
231 }; | |
232 | |
233 class CardTableRS; | |
234 class CMSParGCThreadState; | |
235 | |
236 class ModUnionClosure: public MemRegionClosure { | |
237 protected: | |
238 CMSBitMap* _t; | |
239 public: | |
240 ModUnionClosure(CMSBitMap* t): _t(t) { } | |
241 void do_MemRegion(MemRegion mr); | |
242 }; | |
243 | |
244 class ModUnionClosurePar: public ModUnionClosure { | |
245 public: | |
246 ModUnionClosurePar(CMSBitMap* t): ModUnionClosure(t) { } | |
247 void do_MemRegion(MemRegion mr); | |
248 }; | |
249 | |
250 // Survivor Chunk Array in support of parallelization of | |
251 // Survivor Space rescan. | |
252 class ChunkArray: public CHeapObj { | |
253 size_t _index; | |
254 size_t _capacity; | |
255 HeapWord** _array; // storage for array | |
256 | |
257 public: | |
258 ChunkArray() : _index(0), _capacity(0), _array(NULL) {} | |
259 ChunkArray(HeapWord** a, size_t c): | |
260 _index(0), _capacity(c), _array(a) {} | |
261 | |
262 HeapWord** array() { return _array; } | |
263 void set_array(HeapWord** a) { _array = a; } | |
264 | |
265 size_t capacity() { return _capacity; } | |
266 void set_capacity(size_t c) { _capacity = c; } | |
267 | |
268 size_t end() { | |
269 assert(_index < capacity(), "_index out of bounds"); | |
270 return _index; | |
271 } // exclusive | |
272 | |
273 HeapWord* nth(size_t n) { | |
274 assert(n < end(), "Out of bounds access"); | |
275 return _array[n]; | |
276 } | |
277 | |
278 void reset() { | |
279 _index = 0; | |
280 } | |
281 | |
282 void record_sample(HeapWord* p, size_t sz) { | |
283 // For now we do not do anything with the size | |
284 if (_index < _capacity) { | |
285 _array[_index++] = p; | |
286 } | |
287 } | |
288 }; | |
289 | |
290 // | |
291 // Timing, allocation and promotion statistics for gc scheduling and incremental | |
292 // mode pacing. Most statistics are exponential averages. | |
293 // | |
294 class CMSStats VALUE_OBJ_CLASS_SPEC { | |
295 private: | |
296 ConcurrentMarkSweepGeneration* const _cms_gen; // The cms (old) gen. | |
297 | |
298 // The following are exponential averages with factor alpha: | |
299 // avg = (100 - alpha) * avg + alpha * cur_sample | |
300 // | |
301 // The durations measure: end_time[n] - start_time[n] | |
302 // The periods measure: start_time[n] - start_time[n-1] | |
303 // | |
304 // The cms period and duration include only concurrent collections; time spent | |
305 // in foreground cms collections due to System.gc() or because of a failure to | |
306 // keep up are not included. | |
307 // | |
308 // There are 3 alphas to "bootstrap" the statistics. The _saved_alpha is the | |
309 // real value, but is used only after the first period. A value of 100 is | |
310 // used for the first sample so it gets the entire weight. | |
311 unsigned int _saved_alpha; // 0-100 | |
312 unsigned int _gc0_alpha; | |
313 unsigned int _cms_alpha; | |
314 | |
315 double _gc0_duration; | |
316 double _gc0_period; | |
317 size_t _gc0_promoted; // bytes promoted per gc0 | |
318 double _cms_duration; | |
319 double _cms_duration_pre_sweep; // time from initiation to start of sweep | |
320 double _cms_duration_per_mb; | |
321 double _cms_period; | |
322 size_t _cms_allocated; // bytes of direct allocation per gc0 period | |
323 | |
324 // Timers. | |
325 elapsedTimer _cms_timer; | |
326 TimeStamp _gc0_begin_time; | |
327 TimeStamp _cms_begin_time; | |
328 TimeStamp _cms_end_time; | |
329 | |
330 // Snapshots of the amount used in the CMS generation. | |
331 size_t _cms_used_at_gc0_begin; | |
332 size_t _cms_used_at_gc0_end; | |
333 size_t _cms_used_at_cms_begin; | |
334 | |
335 // Used to prevent the duty cycle from being reduced in the middle of a cms | |
336 // cycle. | |
337 bool _allow_duty_cycle_reduction; | |
338 | |
339 enum { | |
340 _GC0_VALID = 0x1, | |
341 _CMS_VALID = 0x2, | |
342 _ALL_VALID = _GC0_VALID | _CMS_VALID | |
343 }; | |
344 | |
345 unsigned int _valid_bits; | |
346 | |
347 unsigned int _icms_duty_cycle; // icms duty cycle (0-100). | |
348 | |
349 protected: | |
350 | |
351 // Return a duty cycle that avoids wild oscillations, by limiting the amount | |
352 // of change between old_duty_cycle and new_duty_cycle (the latter is treated | |
353 // as a recommended value). | |
354 static unsigned int icms_damped_duty_cycle(unsigned int old_duty_cycle, | |
355 unsigned int new_duty_cycle); | |
356 unsigned int icms_update_duty_cycle_impl(); | |
357 | |
358 public: | |
359 CMSStats(ConcurrentMarkSweepGeneration* cms_gen, | |
360 unsigned int alpha = CMSExpAvgFactor); | |
361 | |
362 // Whether or not the statistics contain valid data; higher level statistics | |
363 // cannot be called until this returns true (they require at least one young | |
364 // gen and one cms cycle to have completed). | |
365 bool valid() const; | |
366 | |
367 // Record statistics. | |
368 void record_gc0_begin(); | |
369 void record_gc0_end(size_t cms_gen_bytes_used); | |
370 void record_cms_begin(); | |
371 void record_cms_end(); | |
372 | |
373 // Allow management of the cms timer, which must be stopped/started around | |
374 // yield points. | |
375 elapsedTimer& cms_timer() { return _cms_timer; } | |
376 void start_cms_timer() { _cms_timer.start(); } | |
377 void stop_cms_timer() { _cms_timer.stop(); } | |
378 | |
379 // Basic statistics; units are seconds or bytes. | |
380 double gc0_period() const { return _gc0_period; } | |
381 double gc0_duration() const { return _gc0_duration; } | |
382 size_t gc0_promoted() const { return _gc0_promoted; } | |
383 double cms_period() const { return _cms_period; } | |
384 double cms_duration() const { return _cms_duration; } | |
385 double cms_duration_per_mb() const { return _cms_duration_per_mb; } | |
386 size_t cms_allocated() const { return _cms_allocated; } | |
387 | |
388 size_t cms_used_at_gc0_end() const { return _cms_used_at_gc0_end;} | |
389 | |
390 // Seconds since the last background cms cycle began or ended. | |
391 double cms_time_since_begin() const; | |
392 double cms_time_since_end() const; | |
393 | |
394 // Higher level statistics--caller must check that valid() returns true before | |
395 // calling. | |
396 | |
397 // Returns bytes promoted per second of wall clock time. | |
398 double promotion_rate() const; | |
399 | |
400 // Returns bytes directly allocated per second of wall clock time. | |
401 double cms_allocation_rate() const; | |
402 | |
403 // Rate at which space in the cms generation is being consumed (sum of the | |
404 // above two). | |
405 double cms_consumption_rate() const; | |
406 | |
407 // Returns an estimate of the number of seconds until the cms generation will | |
408 // fill up, assuming no collection work is done. | |
409 double time_until_cms_gen_full() const; | |
410 | |
411 // Returns an estimate of the number of seconds remaining until | |
412 // the cms generation collection should start. | |
413 double time_until_cms_start() const; | |
414 | |
415 // End of higher level statistics. | |
416 | |
417 // Returns the cms incremental mode duty cycle, as a percentage (0-100). | |
418 unsigned int icms_duty_cycle() const { return _icms_duty_cycle; } | |
419 | |
420 // Update the duty cycle and return the new value. | |
421 unsigned int icms_update_duty_cycle(); | |
422 | |
423 // Debugging. | |
424 void print_on(outputStream* st) const PRODUCT_RETURN; | |
425 void print() const { print_on(gclog_or_tty); } | |
426 }; | |
427 | |
428 // A closure related to weak references processing which | |
429 // we embed in the CMSCollector, since we need to pass | |
430 // it to the reference processor for secondary filtering | |
431 // of references based on reachability of referent; | |
432 // see role of _is_alive_non_header closure in the | |
433 // ReferenceProcessor class. | |
434 // For objects in the CMS generation, this closure checks | |
435 // if the object is "live" (reachable). Used in weak | |
436 // reference processing. | |
437 class CMSIsAliveClosure: public BoolObjectClosure { | |
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438 const MemRegion _span; |
0 | 439 const CMSBitMap* _bit_map; |
440 | |
441 friend class CMSCollector; | |
442 public: | |
443 CMSIsAliveClosure(MemRegion span, | |
444 CMSBitMap* bit_map): | |
445 _span(span), | |
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446 _bit_map(bit_map) { |
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447 assert(!span.is_empty(), "Empty span could spell trouble"); |
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448 } |
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449 |
0 | 450 void do_object(oop obj) { |
451 assert(false, "not to be invoked"); | |
452 } | |
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453 |
0 | 454 bool do_object_b(oop obj); |
455 }; | |
456 | |
457 | |
458 // Implements AbstractRefProcTaskExecutor for CMS. | |
459 class CMSRefProcTaskExecutor: public AbstractRefProcTaskExecutor { | |
460 public: | |
461 | |
462 CMSRefProcTaskExecutor(CMSCollector& collector) | |
463 : _collector(collector) | |
464 { } | |
465 | |
466 // Executes a task using worker threads. | |
467 virtual void execute(ProcessTask& task); | |
468 virtual void execute(EnqueueTask& task); | |
469 private: | |
470 CMSCollector& _collector; | |
471 }; | |
472 | |
473 | |
474 class CMSCollector: public CHeapObj { | |
475 friend class VMStructs; | |
476 friend class ConcurrentMarkSweepThread; | |
477 friend class ConcurrentMarkSweepGeneration; | |
478 friend class CompactibleFreeListSpace; | |
479 friend class CMSParRemarkTask; | |
480 friend class CMSConcMarkingTask; | |
481 friend class CMSRefProcTaskProxy; | |
482 friend class CMSRefProcTaskExecutor; | |
483 friend class ScanMarkedObjectsAgainCarefullyClosure; // for sampling eden | |
484 friend class SurvivorSpacePrecleanClosure; // --- ditto ------- | |
485 friend class PushOrMarkClosure; // to access _restart_addr | |
486 friend class Par_PushOrMarkClosure; // to access _restart_addr | |
487 friend class MarkFromRootsClosure; // -- ditto -- | |
488 // ... and for clearing cards | |
489 friend class Par_MarkFromRootsClosure; // to access _restart_addr | |
490 // ... and for clearing cards | |
491 friend class Par_ConcMarkingClosure; // to access _restart_addr etc. | |
492 friend class MarkFromRootsVerifyClosure; // to access _restart_addr | |
493 friend class PushAndMarkVerifyClosure; // -- ditto -- | |
494 friend class MarkRefsIntoAndScanClosure; // to access _overflow_list | |
495 friend class PushAndMarkClosure; // -- ditto -- | |
496 friend class Par_PushAndMarkClosure; // -- ditto -- | |
497 friend class CMSKeepAliveClosure; // -- ditto -- | |
498 friend class CMSDrainMarkingStackClosure; // -- ditto -- | |
499 friend class CMSInnerParMarkAndPushClosure; // -- ditto -- | |
500 NOT_PRODUCT(friend class ScanMarkedObjectsAgainClosure;) // assertion on _overflow_list | |
501 friend class ReleaseForegroundGC; // to access _foregroundGCShouldWait | |
502 friend class VM_CMS_Operation; | |
503 friend class VM_CMS_Initial_Mark; | |
504 friend class VM_CMS_Final_Remark; | |
505 | |
506 private: | |
507 jlong _time_of_last_gc; | |
508 void update_time_of_last_gc(jlong now) { | |
509 _time_of_last_gc = now; | |
510 } | |
511 | |
512 OopTaskQueueSet* _task_queues; | |
513 | |
514 // Overflow list of grey objects, threaded through mark-word | |
515 // Manipulated with CAS in the parallel/multi-threaded case. | |
516 oop _overflow_list; | |
517 // The following array-pair keeps track of mark words | |
518 // displaced for accomodating overflow list above. | |
519 // This code will likely be revisited under RFE#4922830. | |
520 GrowableArray<oop>* _preserved_oop_stack; | |
521 GrowableArray<markOop>* _preserved_mark_stack; | |
522 | |
523 int* _hash_seed; | |
524 | |
525 // In support of multi-threaded concurrent phases | |
526 YieldingFlexibleWorkGang* _conc_workers; | |
527 | |
528 // Performance Counters | |
529 CollectorCounters* _gc_counters; | |
530 | |
531 // Initialization Errors | |
532 bool _completed_initialization; | |
533 | |
534 // In support of ExplicitGCInvokesConcurrent | |
535 static bool _full_gc_requested; | |
536 unsigned int _collection_count_start; | |
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537 |
0 | 538 // Should we unload classes this concurrent cycle? |
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539 bool _should_unload_classes; |
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540 unsigned int _concurrent_cycles_since_last_unload; |
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541 unsigned int concurrent_cycles_since_last_unload() const { |
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542 return _concurrent_cycles_since_last_unload; |
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543 } |
0 | 544 // Did we (allow) unload classes in the previous concurrent cycle? |
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545 bool unloaded_classes_last_cycle() const { |
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546 return concurrent_cycles_since_last_unload() == 0; |
0 | 547 } |
548 | |
549 // Verification support | |
550 CMSBitMap _verification_mark_bm; | |
551 void verify_after_remark_work_1(); | |
552 void verify_after_remark_work_2(); | |
553 | |
554 // true if any verification flag is on. | |
555 bool _verifying; | |
556 bool verifying() const { return _verifying; } | |
557 void set_verifying(bool v) { _verifying = v; } | |
558 | |
559 // Collector policy | |
560 ConcurrentMarkSweepPolicy* _collector_policy; | |
561 ConcurrentMarkSweepPolicy* collector_policy() { return _collector_policy; } | |
562 | |
563 // Check whether the gc time limit has been | |
564 // exceeded and set the size policy flag | |
565 // appropriately. | |
566 void check_gc_time_limit(); | |
567 // XXX Move these to CMSStats ??? FIX ME !!! | |
568 elapsedTimer _sweep_timer; | |
569 AdaptivePaddedAverage _sweep_estimate; | |
570 | |
571 protected: | |
572 ConcurrentMarkSweepGeneration* _cmsGen; // old gen (CMS) | |
573 ConcurrentMarkSweepGeneration* _permGen; // perm gen | |
574 MemRegion _span; // span covering above two | |
575 CardTableRS* _ct; // card table | |
576 | |
577 // CMS marking support structures | |
578 CMSBitMap _markBitMap; | |
579 CMSBitMap _modUnionTable; | |
580 CMSMarkStack _markStack; | |
581 CMSMarkStack _revisitStack; // used to keep track of klassKlass objects | |
582 // to revisit | |
583 CMSBitMap _perm_gen_verify_bit_map; // Mark bit map for perm gen verification support. | |
584 | |
585 HeapWord* _restart_addr; // in support of marking stack overflow | |
586 void lower_restart_addr(HeapWord* low); | |
587 | |
588 // Counters in support of marking stack / work queue overflow handling: | |
589 // a non-zero value indicates certain types of overflow events during | |
590 // the current CMS cycle and could lead to stack resizing efforts at | |
591 // an opportune future time. | |
592 size_t _ser_pmc_preclean_ovflw; | |
593 size_t _ser_pmc_remark_ovflw; | |
594 size_t _par_pmc_remark_ovflw; | |
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595 size_t _ser_kac_preclean_ovflw; |
0 | 596 size_t _ser_kac_ovflw; |
597 size_t _par_kac_ovflw; | |
534 | 598 NOT_PRODUCT(ssize_t _num_par_pushes;) |
0 | 599 |
600 // ("Weak") Reference processing support | |
601 ReferenceProcessor* _ref_processor; | |
602 CMSIsAliveClosure _is_alive_closure; | |
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603 // keep this textually after _markBitMap and _span; c'tor dependency |
0 | 604 |
605 ConcurrentMarkSweepThread* _cmsThread; // the thread doing the work | |
606 ModUnionClosure _modUnionClosure; | |
607 ModUnionClosurePar _modUnionClosurePar; | |
608 | |
609 // CMS abstract state machine | |
610 // initial_state: Idling | |
611 // next_state(Idling) = {Marking} | |
612 // next_state(Marking) = {Precleaning, Sweeping} | |
613 // next_state(Precleaning) = {AbortablePreclean, FinalMarking} | |
614 // next_state(AbortablePreclean) = {FinalMarking} | |
615 // next_state(FinalMarking) = {Sweeping} | |
616 // next_state(Sweeping) = {Resizing} | |
617 // next_state(Resizing) = {Resetting} | |
618 // next_state(Resetting) = {Idling} | |
619 // The numeric values below are chosen so that: | |
620 // . _collectorState <= Idling == post-sweep && pre-mark | |
621 // . _collectorState in (Idling, Sweeping) == {initial,final}marking || | |
622 // precleaning || abortablePrecleanb | |
623 enum CollectorState { | |
624 Resizing = 0, | |
625 Resetting = 1, | |
626 Idling = 2, | |
627 InitialMarking = 3, | |
628 Marking = 4, | |
629 Precleaning = 5, | |
630 AbortablePreclean = 6, | |
631 FinalMarking = 7, | |
632 Sweeping = 8 | |
633 }; | |
634 static CollectorState _collectorState; | |
635 | |
636 // State related to prologue/epilogue invocation for my generations | |
637 bool _between_prologue_and_epilogue; | |
638 | |
639 // Signalling/State related to coordination between fore- and backgroud GC | |
640 // Note: When the baton has been passed from background GC to foreground GC, | |
641 // _foregroundGCIsActive is true and _foregroundGCShouldWait is false. | |
642 static bool _foregroundGCIsActive; // true iff foreground collector is active or | |
643 // wants to go active | |
644 static bool _foregroundGCShouldWait; // true iff background GC is active and has not | |
645 // yet passed the baton to the foreground GC | |
646 | |
647 // Support for CMSScheduleRemark (abortable preclean) | |
648 bool _abort_preclean; | |
649 bool _start_sampling; | |
650 | |
651 int _numYields; | |
652 size_t _numDirtyCards; | |
653 uint _sweepCount; | |
654 // number of full gc's since the last concurrent gc. | |
655 uint _full_gcs_since_conc_gc; | |
656 | |
657 // occupancy used for bootstrapping stats | |
658 double _bootstrap_occupancy; | |
659 | |
660 // timer | |
661 elapsedTimer _timer; | |
662 | |
663 // Timing, allocation and promotion statistics, used for scheduling. | |
664 CMSStats _stats; | |
665 | |
666 // Allocation limits installed in the young gen, used only in | |
667 // CMSIncrementalMode. When an allocation in the young gen would cross one of | |
668 // these limits, the cms generation is notified and the cms thread is started | |
669 // or stopped, respectively. | |
670 HeapWord* _icms_start_limit; | |
671 HeapWord* _icms_stop_limit; | |
672 | |
673 enum CMS_op_type { | |
674 CMS_op_checkpointRootsInitial, | |
675 CMS_op_checkpointRootsFinal | |
676 }; | |
677 | |
678 void do_CMS_operation(CMS_op_type op); | |
679 bool stop_world_and_do(CMS_op_type op); | |
680 | |
681 OopTaskQueueSet* task_queues() { return _task_queues; } | |
682 int* hash_seed(int i) { return &_hash_seed[i]; } | |
683 YieldingFlexibleWorkGang* conc_workers() { return _conc_workers; } | |
684 | |
685 // Support for parallelizing Eden rescan in CMS remark phase | |
686 void sample_eden(); // ... sample Eden space top | |
687 | |
688 private: | |
689 // Support for parallelizing young gen rescan in CMS remark phase | |
690 Generation* _young_gen; // the younger gen | |
691 HeapWord** _top_addr; // ... Top of Eden | |
692 HeapWord** _end_addr; // ... End of Eden | |
693 HeapWord** _eden_chunk_array; // ... Eden partitioning array | |
694 size_t _eden_chunk_index; // ... top (exclusive) of array | |
695 size_t _eden_chunk_capacity; // ... max entries in array | |
696 | |
697 // Support for parallelizing survivor space rescan | |
698 HeapWord** _survivor_chunk_array; | |
699 size_t _survivor_chunk_index; | |
700 size_t _survivor_chunk_capacity; | |
701 size_t* _cursor; | |
702 ChunkArray* _survivor_plab_array; | |
703 | |
704 // Support for marking stack overflow handling | |
705 bool take_from_overflow_list(size_t num, CMSMarkStack* to_stack); | |
706 bool par_take_from_overflow_list(size_t num, OopTaskQueue* to_work_q); | |
707 void push_on_overflow_list(oop p); | |
708 void par_push_on_overflow_list(oop p); | |
709 // the following is, obviously, not, in general, "MT-stable" | |
710 bool overflow_list_is_empty() const; | |
711 | |
712 void preserve_mark_if_necessary(oop p); | |
713 void par_preserve_mark_if_necessary(oop p); | |
714 void preserve_mark_work(oop p, markOop m); | |
715 void restore_preserved_marks_if_any(); | |
716 NOT_PRODUCT(bool no_preserved_marks() const;) | |
717 // in support of testing overflow code | |
718 NOT_PRODUCT(int _overflow_counter;) | |
719 NOT_PRODUCT(bool simulate_overflow();) // sequential | |
720 NOT_PRODUCT(bool par_simulate_overflow();) // MT version | |
721 | |
722 int _roots_scanning_options; | |
723 int roots_scanning_options() const { return _roots_scanning_options; } | |
724 void add_root_scanning_option(int o) { _roots_scanning_options |= o; } | |
725 void remove_root_scanning_option(int o) { _roots_scanning_options &= ~o; } | |
726 | |
727 // CMS work methods | |
728 void checkpointRootsInitialWork(bool asynch); // initial checkpoint work | |
729 | |
730 // a return value of false indicates failure due to stack overflow | |
731 bool markFromRootsWork(bool asynch); // concurrent marking work | |
732 | |
733 public: // FIX ME!!! only for testing | |
734 bool do_marking_st(bool asynch); // single-threaded marking | |
735 bool do_marking_mt(bool asynch); // multi-threaded marking | |
736 | |
737 private: | |
738 | |
739 // concurrent precleaning work | |
740 size_t preclean_mod_union_table(ConcurrentMarkSweepGeneration* gen, | |
741 ScanMarkedObjectsAgainCarefullyClosure* cl); | |
742 size_t preclean_card_table(ConcurrentMarkSweepGeneration* gen, | |
743 ScanMarkedObjectsAgainCarefullyClosure* cl); | |
744 // Does precleaning work, returning a quantity indicative of | |
745 // the amount of "useful work" done. | |
746 size_t preclean_work(bool clean_refs, bool clean_survivors); | |
747 void abortable_preclean(); // Preclean while looking for possible abort | |
748 void initialize_sequential_subtasks_for_young_gen_rescan(int i); | |
749 // Helper function for above; merge-sorts the per-thread plab samples | |
750 void merge_survivor_plab_arrays(ContiguousSpace* surv); | |
751 // Resets (i.e. clears) the per-thread plab sample vectors | |
752 void reset_survivor_plab_arrays(); | |
753 | |
754 // final (second) checkpoint work | |
755 void checkpointRootsFinalWork(bool asynch, bool clear_all_soft_refs, | |
756 bool init_mark_was_synchronous); | |
757 // work routine for parallel version of remark | |
758 void do_remark_parallel(); | |
759 // work routine for non-parallel version of remark | |
760 void do_remark_non_parallel(); | |
761 // reference processing work routine (during second checkpoint) | |
762 void refProcessingWork(bool asynch, bool clear_all_soft_refs); | |
763 | |
764 // concurrent sweeping work | |
765 void sweepWork(ConcurrentMarkSweepGeneration* gen, bool asynch); | |
766 | |
767 // (concurrent) resetting of support data structures | |
768 void reset(bool asynch); | |
769 | |
770 // Clear _expansion_cause fields of constituent generations | |
771 void clear_expansion_cause(); | |
772 | |
773 // An auxilliary method used to record the ends of | |
774 // used regions of each generation to limit the extent of sweep | |
775 void save_sweep_limits(); | |
776 | |
777 // Resize the generations included in the collector. | |
778 void compute_new_size(); | |
779 | |
780 // A work method used by foreground collection to determine | |
781 // what type of collection (compacting or not, continuing or fresh) | |
782 // it should do. | |
783 void decide_foreground_collection_type(bool clear_all_soft_refs, | |
784 bool* should_compact, bool* should_start_over); | |
785 | |
786 // A work method used by the foreground collector to do | |
787 // a mark-sweep-compact. | |
788 void do_compaction_work(bool clear_all_soft_refs); | |
789 | |
790 // A work method used by the foreground collector to do | |
791 // a mark-sweep, after taking over from a possibly on-going | |
792 // concurrent mark-sweep collection. | |
793 void do_mark_sweep_work(bool clear_all_soft_refs, | |
794 CollectorState first_state, bool should_start_over); | |
795 | |
796 // If the backgrould GC is active, acquire control from the background | |
797 // GC and do the collection. | |
798 void acquire_control_and_collect(bool full, bool clear_all_soft_refs); | |
799 | |
800 // For synchronizing passing of control from background to foreground | |
801 // GC. waitForForegroundGC() is called by the background | |
802 // collector. It if had to wait for a foreground collection, | |
803 // it returns true and the background collection should assume | |
804 // that the collection was finished by the foreground | |
805 // collector. | |
806 bool waitForForegroundGC(); | |
807 | |
808 // Incremental mode triggering: recompute the icms duty cycle and set the | |
809 // allocation limits in the young gen. | |
810 void icms_update_allocation_limits(); | |
811 | |
812 size_t block_size_using_printezis_bits(HeapWord* addr) const; | |
813 size_t block_size_if_printezis_bits(HeapWord* addr) const; | |
814 HeapWord* next_card_start_after_block(HeapWord* addr) const; | |
815 | |
816 void setup_cms_unloading_and_verification_state(); | |
817 public: | |
818 CMSCollector(ConcurrentMarkSweepGeneration* cmsGen, | |
819 ConcurrentMarkSweepGeneration* permGen, | |
820 CardTableRS* ct, | |
821 ConcurrentMarkSweepPolicy* cp); | |
822 ConcurrentMarkSweepThread* cmsThread() { return _cmsThread; } | |
823 | |
824 ReferenceProcessor* ref_processor() { return _ref_processor; } | |
825 void ref_processor_init(); | |
826 | |
827 Mutex* bitMapLock() const { return _markBitMap.lock(); } | |
828 static CollectorState abstract_state() { return _collectorState; } | |
829 | |
830 bool should_abort_preclean() const; // Whether preclean should be aborted. | |
831 size_t get_eden_used() const; | |
832 size_t get_eden_capacity() const; | |
833 | |
834 ConcurrentMarkSweepGeneration* cmsGen() { return _cmsGen; } | |
835 | |
836 // locking checks | |
837 NOT_PRODUCT(static bool have_cms_token();) | |
838 | |
839 // XXXPERM bool should_collect(bool full, size_t size, bool tlab); | |
840 bool shouldConcurrentCollect(); | |
841 | |
842 void collect(bool full, | |
843 bool clear_all_soft_refs, | |
844 size_t size, | |
845 bool tlab); | |
846 void collect_in_background(bool clear_all_soft_refs); | |
847 void collect_in_foreground(bool clear_all_soft_refs); | |
848 | |
849 // In support of ExplicitGCInvokesConcurrent | |
850 static void request_full_gc(unsigned int full_gc_count); | |
851 // Should we unload classes in a particular concurrent cycle? | |
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852 bool should_unload_classes() const { |
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853 return _should_unload_classes; |
0 | 854 } |
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855 bool update_should_unload_classes(); |
0 | 856 |
857 void direct_allocated(HeapWord* start, size_t size); | |
858 | |
859 // Object is dead if not marked and current phase is sweeping. | |
860 bool is_dead_obj(oop obj) const; | |
861 | |
862 // After a promotion (of "start"), do any necessary marking. | |
863 // If "par", then it's being done by a parallel GC thread. | |
864 // The last two args indicate if we need precise marking | |
865 // and if so the size of the object so it can be dirtied | |
866 // in its entirety. | |
867 void promoted(bool par, HeapWord* start, | |
868 bool is_obj_array, size_t obj_size); | |
869 | |
870 HeapWord* allocation_limit_reached(Space* space, HeapWord* top, | |
871 size_t word_size); | |
872 | |
873 void getFreelistLocks() const; | |
874 void releaseFreelistLocks() const; | |
875 bool haveFreelistLocks() const; | |
876 | |
877 // GC prologue and epilogue | |
878 void gc_prologue(bool full); | |
879 void gc_epilogue(bool full); | |
880 | |
881 jlong time_of_last_gc(jlong now) { | |
882 if (_collectorState <= Idling) { | |
883 // gc not in progress | |
884 return _time_of_last_gc; | |
885 } else { | |
886 // collection in progress | |
887 return now; | |
888 } | |
889 } | |
890 | |
891 // Support for parallel remark of survivor space | |
892 void* get_data_recorder(int thr_num); | |
893 | |
894 CMSBitMap* markBitMap() { return &_markBitMap; } | |
895 void directAllocated(HeapWord* start, size_t size); | |
896 | |
897 // main CMS steps and related support | |
898 void checkpointRootsInitial(bool asynch); | |
899 bool markFromRoots(bool asynch); // a return value of false indicates failure | |
900 // due to stack overflow | |
901 void preclean(); | |
902 void checkpointRootsFinal(bool asynch, bool clear_all_soft_refs, | |
903 bool init_mark_was_synchronous); | |
904 void sweep(bool asynch); | |
905 | |
906 // Check that the currently executing thread is the expected | |
907 // one (foreground collector or background collector). | |
908 void check_correct_thread_executing() PRODUCT_RETURN; | |
909 // XXXPERM void print_statistics() PRODUCT_RETURN; | |
910 | |
911 bool is_cms_reachable(HeapWord* addr); | |
912 | |
913 // Performance Counter Support | |
914 CollectorCounters* counters() { return _gc_counters; } | |
915 | |
916 // timer stuff | |
917 void startTimer() { assert(!_timer.is_active(), "Error"); _timer.start(); } | |
918 void stopTimer() { assert( _timer.is_active(), "Error"); _timer.stop(); } | |
919 void resetTimer() { assert(!_timer.is_active(), "Error"); _timer.reset(); } | |
920 double timerValue() { assert(!_timer.is_active(), "Error"); return _timer.seconds(); } | |
921 | |
922 int yields() { return _numYields; } | |
923 void resetYields() { _numYields = 0; } | |
924 void incrementYields() { _numYields++; } | |
925 void resetNumDirtyCards() { _numDirtyCards = 0; } | |
926 void incrementNumDirtyCards(size_t num) { _numDirtyCards += num; } | |
927 size_t numDirtyCards() { return _numDirtyCards; } | |
928 | |
929 static bool foregroundGCShouldWait() { return _foregroundGCShouldWait; } | |
930 static void set_foregroundGCShouldWait(bool v) { _foregroundGCShouldWait = v; } | |
931 static bool foregroundGCIsActive() { return _foregroundGCIsActive; } | |
932 static void set_foregroundGCIsActive(bool v) { _foregroundGCIsActive = v; } | |
933 uint sweepCount() const { return _sweepCount; } | |
934 void incrementSweepCount() { _sweepCount++; } | |
935 | |
936 // Timers/stats for gc scheduling and incremental mode pacing. | |
937 CMSStats& stats() { return _stats; } | |
938 | |
939 // Convenience methods that check whether CMSIncrementalMode is enabled and | |
940 // forward to the corresponding methods in ConcurrentMarkSweepThread. | |
941 static void start_icms(); | |
942 static void stop_icms(); // Called at the end of the cms cycle. | |
943 static void disable_icms(); // Called before a foreground collection. | |
944 static void enable_icms(); // Called after a foreground collection. | |
945 void icms_wait(); // Called at yield points. | |
946 | |
947 // Adaptive size policy | |
948 CMSAdaptiveSizePolicy* size_policy(); | |
949 CMSGCAdaptivePolicyCounters* gc_adaptive_policy_counters(); | |
950 | |
951 // debugging | |
952 void verify(bool); | |
953 bool verify_after_remark(); | |
954 void verify_ok_to_terminate() const PRODUCT_RETURN; | |
955 void verify_work_stacks_empty() const PRODUCT_RETURN; | |
956 void verify_overflow_empty() const PRODUCT_RETURN; | |
957 | |
958 // convenience methods in support of debugging | |
959 static const size_t skip_header_HeapWords() PRODUCT_RETURN0; | |
960 HeapWord* block_start(const void* p) const PRODUCT_RETURN0; | |
961 | |
962 // accessors | |
963 CMSMarkStack* verification_mark_stack() { return &_markStack; } | |
964 CMSBitMap* verification_mark_bm() { return &_verification_mark_bm; } | |
965 | |
966 // Get the bit map with a perm gen "deadness" information. | |
967 CMSBitMap* perm_gen_verify_bit_map() { return &_perm_gen_verify_bit_map; } | |
968 | |
969 // Initialization errors | |
970 bool completed_initialization() { return _completed_initialization; } | |
971 }; | |
972 | |
973 class CMSExpansionCause : public AllStatic { | |
974 public: | |
975 enum Cause { | |
976 _no_expansion, | |
977 _satisfy_free_ratio, | |
978 _satisfy_promotion, | |
979 _satisfy_allocation, | |
980 _allocate_par_lab, | |
981 _allocate_par_spooling_space, | |
982 _adaptive_size_policy | |
983 }; | |
984 // Return a string describing the cause of the expansion. | |
985 static const char* to_string(CMSExpansionCause::Cause cause); | |
986 }; | |
987 | |
988 class ConcurrentMarkSweepGeneration: public CardGeneration { | |
989 friend class VMStructs; | |
990 friend class ConcurrentMarkSweepThread; | |
991 friend class ConcurrentMarkSweep; | |
992 friend class CMSCollector; | |
993 protected: | |
994 static CMSCollector* _collector; // the collector that collects us | |
995 CompactibleFreeListSpace* _cmsSpace; // underlying space (only one for now) | |
996 | |
997 // Performance Counters | |
998 GenerationCounters* _gen_counters; | |
999 GSpaceCounters* _space_counters; | |
1000 | |
1001 // Words directly allocated, used by CMSStats. | |
1002 size_t _direct_allocated_words; | |
1003 | |
1004 // Non-product stat counters | |
1005 NOT_PRODUCT( | |
1006 int _numObjectsPromoted; | |
1007 int _numWordsPromoted; | |
1008 int _numObjectsAllocated; | |
1009 int _numWordsAllocated; | |
1010 ) | |
1011 | |
1012 // Used for sizing decisions | |
1013 bool _incremental_collection_failed; | |
1014 bool incremental_collection_failed() { | |
1015 return _incremental_collection_failed; | |
1016 } | |
1017 void set_incremental_collection_failed() { | |
1018 _incremental_collection_failed = true; | |
1019 } | |
1020 void clear_incremental_collection_failed() { | |
1021 _incremental_collection_failed = false; | |
1022 } | |
1023 | |
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1024 // accessors |
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1025 void set_expansion_cause(CMSExpansionCause::Cause v) { _expansion_cause = v;} |
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1026 CMSExpansionCause::Cause expansion_cause() const { return _expansion_cause; } |
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1027 |
0 | 1028 private: |
1029 // For parallel young-gen GC support. | |
1030 CMSParGCThreadState** _par_gc_thread_states; | |
1031 | |
1032 // Reason generation was expanded | |
1033 CMSExpansionCause::Cause _expansion_cause; | |
1034 | |
1035 // In support of MinChunkSize being larger than min object size | |
1036 const double _dilatation_factor; | |
1037 | |
1038 enum CollectionTypes { | |
1039 Concurrent_collection_type = 0, | |
1040 MS_foreground_collection_type = 1, | |
1041 MSC_foreground_collection_type = 2, | |
1042 Unknown_collection_type = 3 | |
1043 }; | |
1044 | |
1045 CollectionTypes _debug_collection_type; | |
1046 | |
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1047 // Fraction of current occupancy at which to start a CMS collection which |
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1048 // will collect this generation (at least). |
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1049 double _initiating_occupancy; |
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1050 |
0 | 1051 protected: |
1052 // Shrink generation by specified size (returns false if unable to shrink) | |
1053 virtual void shrink_by(size_t bytes); | |
1054 | |
1055 // Update statistics for GC | |
1056 virtual void update_gc_stats(int level, bool full); | |
1057 | |
1058 // Maximum available space in the generation (including uncommitted) | |
1059 // space. | |
1060 size_t max_available() const; | |
1061 | |
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1062 // getter and initializer for _initiating_occupancy field. |
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1063 double initiating_occupancy() const { return _initiating_occupancy; } |
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1064 void init_initiating_occupancy(intx io, intx tr); |
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1065 |
0 | 1066 public: |
1067 ConcurrentMarkSweepGeneration(ReservedSpace rs, size_t initial_byte_size, | |
1068 int level, CardTableRS* ct, | |
1069 bool use_adaptive_freelists, | |
1070 FreeBlockDictionary::DictionaryChoice); | |
1071 | |
1072 // Accessors | |
1073 CMSCollector* collector() const { return _collector; } | |
1074 static void set_collector(CMSCollector* collector) { | |
1075 assert(_collector == NULL, "already set"); | |
1076 _collector = collector; | |
1077 } | |
1078 CompactibleFreeListSpace* cmsSpace() const { return _cmsSpace; } | |
1079 | |
1080 Mutex* freelistLock() const; | |
1081 | |
1082 virtual Generation::Name kind() { return Generation::ConcurrentMarkSweep; } | |
1083 | |
1084 // Adaptive size policy | |
1085 CMSAdaptiveSizePolicy* size_policy(); | |
1086 | |
1087 bool refs_discovery_is_atomic() const { return false; } | |
1088 bool refs_discovery_is_mt() const { | |
1089 // Note: CMS does MT-discovery during the parallel-remark | |
1090 // phases. Use ReferenceProcessorMTMutator to make refs | |
1091 // discovery MT-safe during such phases or other parallel | |
1092 // discovery phases in the future. This may all go away | |
1093 // if/when we decide that refs discovery is sufficiently | |
1094 // rare that the cost of the CAS's involved is in the | |
1095 // noise. That's a measurement that should be done, and | |
1096 // the code simplified if that turns out to be the case. | |
1097 return false; | |
1098 } | |
1099 | |
1100 // Override | |
1101 virtual void ref_processor_init(); | |
1102 | |
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1103 // Grow generation by specified size (returns false if unable to grow) |
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1104 bool grow_by(size_t bytes); |
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1105 // Grow generation to reserved size. |
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1106 bool grow_to_reserved(); |
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1107 |
0 | 1108 void clear_expansion_cause() { _expansion_cause = CMSExpansionCause::_no_expansion; } |
1109 | |
1110 // Space enquiries | |
1111 size_t capacity() const; | |
1112 size_t used() const; | |
1113 size_t free() const; | |
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1114 double occupancy() const { return ((double)used())/((double)capacity()); } |
0 | 1115 size_t contiguous_available() const; |
1116 size_t unsafe_max_alloc_nogc() const; | |
1117 | |
1118 // over-rides | |
1119 MemRegion used_region() const; | |
1120 MemRegion used_region_at_save_marks() const; | |
1121 | |
1122 // Does a "full" (forced) collection invoked on this generation collect | |
1123 // all younger generations as well? Note that the second conjunct is a | |
1124 // hack to allow the collection of the younger gen first if the flag is | |
1125 // set. This is better than using th policy's should_collect_gen0_first() | |
1126 // since that causes us to do an extra unnecessary pair of restart-&-stop-world. | |
1127 virtual bool full_collects_younger_generations() const { | |
1128 return UseCMSCompactAtFullCollection && !CollectGen0First; | |
1129 } | |
1130 | |
1131 void space_iterate(SpaceClosure* blk, bool usedOnly = false); | |
1132 | |
1133 // Support for compaction | |
1134 CompactibleSpace* first_compaction_space() const; | |
1135 // Adjust quantites in the generation affected by | |
1136 // the compaction. | |
1137 void reset_after_compaction(); | |
1138 | |
1139 // Allocation support | |
1140 HeapWord* allocate(size_t size, bool tlab); | |
1141 HeapWord* have_lock_and_allocate(size_t size, bool tlab); | |
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1142 oop promote(oop obj, size_t obj_size); |
0 | 1143 HeapWord* par_allocate(size_t size, bool tlab) { |
1144 return allocate(size, tlab); | |
1145 } | |
1146 | |
1147 // Incremental mode triggering. | |
1148 HeapWord* allocation_limit_reached(Space* space, HeapWord* top, | |
1149 size_t word_size); | |
1150 | |
1151 // Used by CMSStats to track direct allocation. The value is sampled and | |
1152 // reset after each young gen collection. | |
1153 size_t direct_allocated_words() const { return _direct_allocated_words; } | |
1154 void reset_direct_allocated_words() { _direct_allocated_words = 0; } | |
1155 | |
1156 // Overrides for parallel promotion. | |
1157 virtual oop par_promote(int thread_num, | |
1158 oop obj, markOop m, size_t word_sz); | |
1159 // This one should not be called for CMS. | |
1160 virtual void par_promote_alloc_undo(int thread_num, | |
1161 HeapWord* obj, size_t word_sz); | |
1162 virtual void par_promote_alloc_done(int thread_num); | |
1163 virtual void par_oop_since_save_marks_iterate_done(int thread_num); | |
1164 | |
1165 virtual bool promotion_attempt_is_safe(size_t promotion_in_bytes, | |
1166 bool younger_handles_promotion_failure) const; | |
1167 | |
1168 bool should_collect(bool full, size_t size, bool tlab); | |
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1169 virtual bool should_concurrent_collect() const; |
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1170 virtual bool is_too_full() const; |
0 | 1171 void collect(bool full, |
1172 bool clear_all_soft_refs, | |
1173 size_t size, | |
1174 bool tlab); | |
1175 | |
1176 HeapWord* expand_and_allocate(size_t word_size, | |
1177 bool tlab, | |
1178 bool parallel = false); | |
1179 | |
1180 // GC prologue and epilogue | |
1181 void gc_prologue(bool full); | |
1182 void gc_prologue_work(bool full, bool registerClosure, | |
1183 ModUnionClosure* modUnionClosure); | |
1184 void gc_epilogue(bool full); | |
1185 void gc_epilogue_work(bool full); | |
1186 | |
1187 // Time since last GC of this generation | |
1188 jlong time_of_last_gc(jlong now) { | |
1189 return collector()->time_of_last_gc(now); | |
1190 } | |
1191 void update_time_of_last_gc(jlong now) { | |
1192 collector()-> update_time_of_last_gc(now); | |
1193 } | |
1194 | |
1195 // Allocation failure | |
1196 void expand(size_t bytes, size_t expand_bytes, | |
1197 CMSExpansionCause::Cause cause); | |
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1198 virtual bool expand(size_t bytes, size_t expand_bytes); |
0 | 1199 void shrink(size_t bytes); |
1200 HeapWord* expand_and_par_lab_allocate(CMSParGCThreadState* ps, size_t word_sz); | |
1201 bool expand_and_ensure_spooling_space(PromotionInfo* promo); | |
1202 | |
1203 // Iteration support and related enquiries | |
1204 void save_marks(); | |
1205 bool no_allocs_since_save_marks(); | |
1206 void object_iterate_since_last_GC(ObjectClosure* cl); | |
1207 void younger_refs_iterate(OopsInGenClosure* cl); | |
1208 | |
1209 // Iteration support specific to CMS generations | |
1210 void save_sweep_limit(); | |
1211 | |
1212 // More iteration support | |
1213 virtual void oop_iterate(MemRegion mr, OopClosure* cl); | |
1214 virtual void oop_iterate(OopClosure* cl); | |
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1215 virtual void safe_object_iterate(ObjectClosure* cl); |
0 | 1216 virtual void object_iterate(ObjectClosure* cl); |
1217 | |
1218 // Need to declare the full complement of closures, whether we'll | |
1219 // override them or not, or get message from the compiler: | |
1220 // oop_since_save_marks_iterate_nv hides virtual function... | |
1221 #define CMS_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \ | |
1222 void oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl); | |
1223 ALL_SINCE_SAVE_MARKS_CLOSURES(CMS_SINCE_SAVE_MARKS_DECL) | |
1224 | |
1225 // Smart allocation XXX -- move to CFLSpace? | |
1226 void setNearLargestChunk(); | |
1227 bool isNearLargestChunk(HeapWord* addr); | |
1228 | |
1229 // Get the chunk at the end of the space. Delagates to | |
1230 // the space. | |
1231 FreeChunk* find_chunk_at_end(); | |
1232 | |
1233 // Overriding of unused functionality (sharing not yet supported with CMS) | |
1234 void pre_adjust_pointers(); | |
1235 void post_compact(); | |
1236 | |
1237 // Debugging | |
1238 void prepare_for_verify(); | |
1239 void verify(bool allow_dirty); | |
1240 void print_statistics() PRODUCT_RETURN; | |
1241 | |
1242 // Performance Counters support | |
1243 virtual void update_counters(); | |
1244 virtual void update_counters(size_t used); | |
1245 void initialize_performance_counters(); | |
1246 CollectorCounters* counters() { return collector()->counters(); } | |
1247 | |
1248 // Support for parallel remark of survivor space | |
1249 void* get_data_recorder(int thr_num) { | |
1250 //Delegate to collector | |
1251 return collector()->get_data_recorder(thr_num); | |
1252 } | |
1253 | |
1254 // Printing | |
1255 const char* name() const; | |
1256 virtual const char* short_name() const { return "CMS"; } | |
1257 void print() const; | |
1258 void printOccupancy(const char* s); | |
1259 bool must_be_youngest() const { return false; } | |
1260 bool must_be_oldest() const { return true; } | |
1261 | |
1262 void compute_new_size(); | |
1263 | |
1264 CollectionTypes debug_collection_type() { return _debug_collection_type; } | |
1265 void rotate_debug_collection_type(); | |
1266 }; | |
1267 | |
1268 class ASConcurrentMarkSweepGeneration : public ConcurrentMarkSweepGeneration { | |
1269 | |
1270 // Return the size policy from the heap's collector | |
1271 // policy casted to CMSAdaptiveSizePolicy*. | |
1272 CMSAdaptiveSizePolicy* cms_size_policy() const; | |
1273 | |
1274 // Resize the generation based on the adaptive size | |
1275 // policy. | |
1276 void resize(size_t cur_promo, size_t desired_promo); | |
1277 | |
1278 // Return the GC counters from the collector policy | |
1279 CMSGCAdaptivePolicyCounters* gc_adaptive_policy_counters(); | |
1280 | |
1281 virtual void shrink_by(size_t bytes); | |
1282 | |
1283 public: | |
1284 virtual void compute_new_size(); | |
1285 ASConcurrentMarkSweepGeneration(ReservedSpace rs, size_t initial_byte_size, | |
1286 int level, CardTableRS* ct, | |
1287 bool use_adaptive_freelists, | |
1288 FreeBlockDictionary::DictionaryChoice | |
1289 dictionaryChoice) : | |
1290 ConcurrentMarkSweepGeneration(rs, initial_byte_size, level, ct, | |
1291 use_adaptive_freelists, dictionaryChoice) {} | |
1292 | |
1293 virtual const char* short_name() const { return "ASCMS"; } | |
1294 virtual Generation::Name kind() { return Generation::ASConcurrentMarkSweep; } | |
1295 | |
1296 virtual void update_counters(); | |
1297 virtual void update_counters(size_t used); | |
1298 }; | |
1299 | |
1300 // | |
1301 // Closures of various sorts used by CMS to accomplish its work | |
1302 // | |
1303 | |
1304 // This closure is used to check that a certain set of oops is empty. | |
1305 class FalseClosure: public OopClosure { | |
1306 public: | |
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1307 void do_oop(oop* p) { guarantee(false, "Should be an empty set"); } |
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1308 void do_oop(narrowOop* p) { guarantee(false, "Should be an empty set"); } |
0 | 1309 }; |
1310 | |
1311 // This closure is used to do concurrent marking from the roots | |
1312 // following the first checkpoint. | |
1313 class MarkFromRootsClosure: public BitMapClosure { | |
1314 CMSCollector* _collector; | |
1315 MemRegion _span; | |
1316 CMSBitMap* _bitMap; | |
1317 CMSBitMap* _mut; | |
1318 CMSMarkStack* _markStack; | |
1319 CMSMarkStack* _revisitStack; | |
1320 bool _yield; | |
1321 int _skipBits; | |
1322 HeapWord* _finger; | |
1323 HeapWord* _threshold; | |
1324 DEBUG_ONLY(bool _verifying;) | |
1325 | |
1326 public: | |
1327 MarkFromRootsClosure(CMSCollector* collector, MemRegion span, | |
1328 CMSBitMap* bitMap, | |
1329 CMSMarkStack* markStack, | |
1330 CMSMarkStack* revisitStack, | |
1331 bool should_yield, bool verifying = false); | |
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1332 bool do_bit(size_t offset); |
0 | 1333 void reset(HeapWord* addr); |
1334 inline void do_yield_check(); | |
1335 | |
1336 private: | |
1337 void scanOopsInOop(HeapWord* ptr); | |
1338 void do_yield_work(); | |
1339 }; | |
1340 | |
1341 // This closure is used to do concurrent multi-threaded | |
1342 // marking from the roots following the first checkpoint. | |
1343 // XXX This should really be a subclass of The serial version | |
1344 // above, but i have not had the time to refactor things cleanly. | |
1345 // That willbe done for Dolphin. | |
1346 class Par_MarkFromRootsClosure: public BitMapClosure { | |
1347 CMSCollector* _collector; | |
1348 MemRegion _whole_span; | |
1349 MemRegion _span; | |
1350 CMSBitMap* _bit_map; | |
1351 CMSBitMap* _mut; | |
1352 OopTaskQueue* _work_queue; | |
1353 CMSMarkStack* _overflow_stack; | |
1354 CMSMarkStack* _revisit_stack; | |
1355 bool _yield; | |
1356 int _skip_bits; | |
1357 HeapWord* _finger; | |
1358 HeapWord* _threshold; | |
1359 CMSConcMarkingTask* _task; | |
1360 public: | |
1361 Par_MarkFromRootsClosure(CMSConcMarkingTask* task, CMSCollector* collector, | |
1362 MemRegion span, | |
1363 CMSBitMap* bit_map, | |
1364 OopTaskQueue* work_queue, | |
1365 CMSMarkStack* overflow_stack, | |
1366 CMSMarkStack* revisit_stack, | |
1367 bool should_yield); | |
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1368 bool do_bit(size_t offset); |
0 | 1369 inline void do_yield_check(); |
1370 | |
1371 private: | |
1372 void scan_oops_in_oop(HeapWord* ptr); | |
1373 void do_yield_work(); | |
1374 bool get_work_from_overflow_stack(); | |
1375 }; | |
1376 | |
1377 // The following closures are used to do certain kinds of verification of | |
1378 // CMS marking. | |
1379 class PushAndMarkVerifyClosure: public OopClosure { | |
1380 CMSCollector* _collector; | |
1381 MemRegion _span; | |
1382 CMSBitMap* _verification_bm; | |
1383 CMSBitMap* _cms_bm; | |
1384 CMSMarkStack* _mark_stack; | |
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1385 protected: |
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1386 void do_oop(oop p); |
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1387 template <class T> inline void do_oop_work(T *p) { |
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1388 oop obj = oopDesc::load_decode_heap_oop_not_null(p); |
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1389 do_oop(obj); |
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1390 } |
0 | 1391 public: |
1392 PushAndMarkVerifyClosure(CMSCollector* cms_collector, | |
1393 MemRegion span, | |
1394 CMSBitMap* verification_bm, | |
1395 CMSBitMap* cms_bm, | |
1396 CMSMarkStack* mark_stack); | |
1397 void do_oop(oop* p); | |
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1398 void do_oop(narrowOop* p); |
0 | 1399 // Deal with a stack overflow condition |
1400 void handle_stack_overflow(HeapWord* lost); | |
1401 }; | |
1402 | |
1403 class MarkFromRootsVerifyClosure: public BitMapClosure { | |
1404 CMSCollector* _collector; | |
1405 MemRegion _span; | |
1406 CMSBitMap* _verification_bm; | |
1407 CMSBitMap* _cms_bm; | |
1408 CMSMarkStack* _mark_stack; | |
1409 HeapWord* _finger; | |
1410 PushAndMarkVerifyClosure _pam_verify_closure; | |
1411 public: | |
1412 MarkFromRootsVerifyClosure(CMSCollector* collector, MemRegion span, | |
1413 CMSBitMap* verification_bm, | |
1414 CMSBitMap* cms_bm, | |
1415 CMSMarkStack* mark_stack); | |
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1416 bool do_bit(size_t offset); |
0 | 1417 void reset(HeapWord* addr); |
1418 }; | |
1419 | |
1420 | |
1421 // This closure is used to check that a certain set of bits is | |
1422 // "empty" (i.e. the bit vector doesn't have any 1-bits). | |
1423 class FalseBitMapClosure: public BitMapClosure { | |
1424 public: | |
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1425 bool do_bit(size_t offset) { |
0 | 1426 guarantee(false, "Should not have a 1 bit"); |
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1427 return true; |
0 | 1428 } |
1429 }; | |
1430 | |
1431 // This closure is used during the second checkpointing phase | |
1432 // to rescan the marked objects on the dirty cards in the mod | |
1433 // union table and the card table proper. It's invoked via | |
1434 // MarkFromDirtyCardsClosure below. It uses either | |
1435 // [Par_]MarkRefsIntoAndScanClosure (Par_ in the parallel case) | |
1436 // declared in genOopClosures.hpp to accomplish some of its work. | |
1437 // In the parallel case the bitMap is shared, so access to | |
1438 // it needs to be suitably synchronized for updates by embedded | |
1439 // closures that update it; however, this closure itself only | |
1440 // reads the bit_map and because it is idempotent, is immune to | |
1441 // reading stale values. | |
1442 class ScanMarkedObjectsAgainClosure: public UpwardsObjectClosure { | |
1443 #ifdef ASSERT | |
1444 CMSCollector* _collector; | |
1445 MemRegion _span; | |
1446 union { | |
1447 CMSMarkStack* _mark_stack; | |
1448 OopTaskQueue* _work_queue; | |
1449 }; | |
1450 #endif // ASSERT | |
1451 bool _parallel; | |
1452 CMSBitMap* _bit_map; | |
1453 union { | |
1454 MarkRefsIntoAndScanClosure* _scan_closure; | |
1455 Par_MarkRefsIntoAndScanClosure* _par_scan_closure; | |
1456 }; | |
1457 | |
1458 public: | |
1459 ScanMarkedObjectsAgainClosure(CMSCollector* collector, | |
1460 MemRegion span, | |
1461 ReferenceProcessor* rp, | |
1462 CMSBitMap* bit_map, | |
1463 CMSMarkStack* mark_stack, | |
1464 CMSMarkStack* revisit_stack, | |
1465 MarkRefsIntoAndScanClosure* cl): | |
1466 #ifdef ASSERT | |
1467 _collector(collector), | |
1468 _span(span), | |
1469 _mark_stack(mark_stack), | |
1470 #endif // ASSERT | |
1471 _parallel(false), | |
1472 _bit_map(bit_map), | |
1473 _scan_closure(cl) { } | |
1474 | |
1475 ScanMarkedObjectsAgainClosure(CMSCollector* collector, | |
1476 MemRegion span, | |
1477 ReferenceProcessor* rp, | |
1478 CMSBitMap* bit_map, | |
1479 OopTaskQueue* work_queue, | |
1480 CMSMarkStack* revisit_stack, | |
1481 Par_MarkRefsIntoAndScanClosure* cl): | |
1482 #ifdef ASSERT | |
1483 _collector(collector), | |
1484 _span(span), | |
1485 _work_queue(work_queue), | |
1486 #endif // ASSERT | |
1487 _parallel(true), | |
1488 _bit_map(bit_map), | |
1489 _par_scan_closure(cl) { } | |
1490 | |
1491 void do_object(oop obj) { | |
1492 guarantee(false, "Call do_object_b(oop, MemRegion) instead"); | |
1493 } | |
1494 bool do_object_b(oop obj) { | |
1495 guarantee(false, "Call do_object_b(oop, MemRegion) form instead"); | |
1496 return false; | |
1497 } | |
1498 bool do_object_bm(oop p, MemRegion mr); | |
1499 }; | |
1500 | |
1501 // This closure is used during the second checkpointing phase | |
1502 // to rescan the marked objects on the dirty cards in the mod | |
1503 // union table and the card table proper. It invokes | |
1504 // ScanMarkedObjectsAgainClosure above to accomplish much of its work. | |
1505 // In the parallel case, the bit map is shared and requires | |
1506 // synchronized access. | |
1507 class MarkFromDirtyCardsClosure: public MemRegionClosure { | |
1508 CompactibleFreeListSpace* _space; | |
1509 ScanMarkedObjectsAgainClosure _scan_cl; | |
1510 size_t _num_dirty_cards; | |
1511 | |
1512 public: | |
1513 MarkFromDirtyCardsClosure(CMSCollector* collector, | |
1514 MemRegion span, | |
1515 CompactibleFreeListSpace* space, | |
1516 CMSBitMap* bit_map, | |
1517 CMSMarkStack* mark_stack, | |
1518 CMSMarkStack* revisit_stack, | |
1519 MarkRefsIntoAndScanClosure* cl): | |
1520 _space(space), | |
1521 _num_dirty_cards(0), | |
1522 _scan_cl(collector, span, collector->ref_processor(), bit_map, | |
1523 mark_stack, revisit_stack, cl) { } | |
1524 | |
1525 MarkFromDirtyCardsClosure(CMSCollector* collector, | |
1526 MemRegion span, | |
1527 CompactibleFreeListSpace* space, | |
1528 CMSBitMap* bit_map, | |
1529 OopTaskQueue* work_queue, | |
1530 CMSMarkStack* revisit_stack, | |
1531 Par_MarkRefsIntoAndScanClosure* cl): | |
1532 _space(space), | |
1533 _num_dirty_cards(0), | |
1534 _scan_cl(collector, span, collector->ref_processor(), bit_map, | |
1535 work_queue, revisit_stack, cl) { } | |
1536 | |
1537 void do_MemRegion(MemRegion mr); | |
1538 void set_space(CompactibleFreeListSpace* space) { _space = space; } | |
1539 size_t num_dirty_cards() { return _num_dirty_cards; } | |
1540 }; | |
1541 | |
1542 // This closure is used in the non-product build to check | |
1543 // that there are no MemRegions with a certain property. | |
1544 class FalseMemRegionClosure: public MemRegionClosure { | |
1545 void do_MemRegion(MemRegion mr) { | |
1546 guarantee(!mr.is_empty(), "Shouldn't be empty"); | |
1547 guarantee(false, "Should never be here"); | |
1548 } | |
1549 }; | |
1550 | |
1551 // This closure is used during the precleaning phase | |
1552 // to "carefully" rescan marked objects on dirty cards. | |
1553 // It uses MarkRefsIntoAndScanClosure declared in genOopClosures.hpp | |
1554 // to accomplish some of its work. | |
1555 class ScanMarkedObjectsAgainCarefullyClosure: public ObjectClosureCareful { | |
1556 CMSCollector* _collector; | |
1557 MemRegion _span; | |
1558 bool _yield; | |
1559 Mutex* _freelistLock; | |
1560 CMSBitMap* _bitMap; | |
1561 CMSMarkStack* _markStack; | |
1562 MarkRefsIntoAndScanClosure* _scanningClosure; | |
1563 | |
1564 public: | |
1565 ScanMarkedObjectsAgainCarefullyClosure(CMSCollector* collector, | |
1566 MemRegion span, | |
1567 CMSBitMap* bitMap, | |
1568 CMSMarkStack* markStack, | |
1569 CMSMarkStack* revisitStack, | |
1570 MarkRefsIntoAndScanClosure* cl, | |
1571 bool should_yield): | |
1572 _collector(collector), | |
1573 _span(span), | |
1574 _yield(should_yield), | |
1575 _bitMap(bitMap), | |
1576 _markStack(markStack), | |
1577 _scanningClosure(cl) { | |
1578 } | |
1579 | |
1580 void do_object(oop p) { | |
1581 guarantee(false, "call do_object_careful instead"); | |
1582 } | |
1583 | |
1584 size_t do_object_careful(oop p) { | |
1585 guarantee(false, "Unexpected caller"); | |
1586 return 0; | |
1587 } | |
1588 | |
1589 size_t do_object_careful_m(oop p, MemRegion mr); | |
1590 | |
1591 void setFreelistLock(Mutex* m) { | |
1592 _freelistLock = m; | |
1593 _scanningClosure->set_freelistLock(m); | |
1594 } | |
1595 | |
1596 private: | |
1597 inline bool do_yield_check(); | |
1598 | |
1599 void do_yield_work(); | |
1600 }; | |
1601 | |
1602 class SurvivorSpacePrecleanClosure: public ObjectClosureCareful { | |
1603 CMSCollector* _collector; | |
1604 MemRegion _span; | |
1605 bool _yield; | |
1606 CMSBitMap* _bit_map; | |
1607 CMSMarkStack* _mark_stack; | |
1608 PushAndMarkClosure* _scanning_closure; | |
1609 unsigned int _before_count; | |
1610 | |
1611 public: | |
1612 SurvivorSpacePrecleanClosure(CMSCollector* collector, | |
1613 MemRegion span, | |
1614 CMSBitMap* bit_map, | |
1615 CMSMarkStack* mark_stack, | |
1616 PushAndMarkClosure* cl, | |
1617 unsigned int before_count, | |
1618 bool should_yield): | |
1619 _collector(collector), | |
1620 _span(span), | |
1621 _yield(should_yield), | |
1622 _bit_map(bit_map), | |
1623 _mark_stack(mark_stack), | |
1624 _scanning_closure(cl), | |
1625 _before_count(before_count) | |
1626 { } | |
1627 | |
1628 void do_object(oop p) { | |
1629 guarantee(false, "call do_object_careful instead"); | |
1630 } | |
1631 | |
1632 size_t do_object_careful(oop p); | |
1633 | |
1634 size_t do_object_careful_m(oop p, MemRegion mr) { | |
1635 guarantee(false, "Unexpected caller"); | |
1636 return 0; | |
1637 } | |
1638 | |
1639 private: | |
1640 inline void do_yield_check(); | |
1641 void do_yield_work(); | |
1642 }; | |
1643 | |
1644 // This closure is used to accomplish the sweeping work | |
1645 // after the second checkpoint but before the concurrent reset | |
1646 // phase. | |
1647 // | |
1648 // Terminology | |
1649 // left hand chunk (LHC) - block of one or more chunks currently being | |
1650 // coalesced. The LHC is available for coalescing with a new chunk. | |
1651 // right hand chunk (RHC) - block that is currently being swept that is | |
1652 // free or garbage that can be coalesced with the LHC. | |
1653 // _inFreeRange is true if there is currently a LHC | |
1654 // _lastFreeRangeCoalesced is true if the LHC consists of more than one chunk. | |
1655 // _freeRangeInFreeLists is true if the LHC is in the free lists. | |
1656 // _freeFinger is the address of the current LHC | |
1657 class SweepClosure: public BlkClosureCareful { | |
1658 CMSCollector* _collector; // collector doing the work | |
1659 ConcurrentMarkSweepGeneration* _g; // Generation being swept | |
1660 CompactibleFreeListSpace* _sp; // Space being swept | |
1661 HeapWord* _limit; | |
1662 Mutex* _freelistLock; // Free list lock (in space) | |
1663 CMSBitMap* _bitMap; // Marking bit map (in | |
1664 // generation) | |
1665 bool _inFreeRange; // Indicates if we are in the | |
1666 // midst of a free run | |
1667 bool _freeRangeInFreeLists; | |
1668 // Often, we have just found | |
1669 // a free chunk and started | |
1670 // a new free range; we do not | |
1671 // eagerly remove this chunk from | |
1672 // the free lists unless there is | |
1673 // a possibility of coalescing. | |
1674 // When true, this flag indicates | |
1675 // that the _freeFinger below | |
1676 // points to a potentially free chunk | |
1677 // that may still be in the free lists | |
1678 bool _lastFreeRangeCoalesced; | |
1679 // free range contains chunks | |
1680 // coalesced | |
1681 bool _yield; | |
1682 // Whether sweeping should be | |
1683 // done with yields. For instance | |
1684 // when done by the foreground | |
1685 // collector we shouldn't yield. | |
1686 HeapWord* _freeFinger; // When _inFreeRange is set, the | |
1687 // pointer to the "left hand | |
1688 // chunk" | |
1689 size_t _freeRangeSize; | |
1690 // When _inFreeRange is set, this | |
1691 // indicates the accumulated size | |
1692 // of the "left hand chunk" | |
1693 NOT_PRODUCT( | |
1694 size_t _numObjectsFreed; | |
1695 size_t _numWordsFreed; | |
1696 size_t _numObjectsLive; | |
1697 size_t _numWordsLive; | |
1698 size_t _numObjectsAlreadyFree; | |
1699 size_t _numWordsAlreadyFree; | |
1700 FreeChunk* _last_fc; | |
1701 ) | |
1702 private: | |
1703 // Code that is common to a free chunk or garbage when | |
1704 // encountered during sweeping. | |
1705 void doPostIsFreeOrGarbageChunk(FreeChunk *fc, | |
1706 size_t chunkSize); | |
1707 // Process a free chunk during sweeping. | |
1708 void doAlreadyFreeChunk(FreeChunk *fc); | |
1709 // Process a garbage chunk during sweeping. | |
1710 size_t doGarbageChunk(FreeChunk *fc); | |
1711 // Process a live chunk during sweeping. | |
1712 size_t doLiveChunk(FreeChunk* fc); | |
1713 | |
1714 // Accessors. | |
1715 HeapWord* freeFinger() const { return _freeFinger; } | |
1716 void set_freeFinger(HeapWord* v) { _freeFinger = v; } | |
1717 size_t freeRangeSize() const { return _freeRangeSize; } | |
1718 void set_freeRangeSize(size_t v) { _freeRangeSize = v; } | |
1719 bool inFreeRange() const { return _inFreeRange; } | |
1720 void set_inFreeRange(bool v) { _inFreeRange = v; } | |
1721 bool lastFreeRangeCoalesced() const { return _lastFreeRangeCoalesced; } | |
1722 void set_lastFreeRangeCoalesced(bool v) { _lastFreeRangeCoalesced = v; } | |
1723 bool freeRangeInFreeLists() const { return _freeRangeInFreeLists; } | |
1724 void set_freeRangeInFreeLists(bool v) { _freeRangeInFreeLists = v; } | |
1725 | |
1726 // Initialize a free range. | |
1727 void initialize_free_range(HeapWord* freeFinger, bool freeRangeInFreeLists); | |
1728 // Return this chunk to the free lists. | |
1729 void flushCurFreeChunk(HeapWord* chunk, size_t size); | |
1730 | |
1731 // Check if we should yield and do so when necessary. | |
1732 inline void do_yield_check(HeapWord* addr); | |
1733 | |
1734 // Yield | |
1735 void do_yield_work(HeapWord* addr); | |
1736 | |
1737 // Debugging/Printing | |
1738 void record_free_block_coalesced(FreeChunk* fc) const PRODUCT_RETURN; | |
1739 | |
1740 public: | |
1741 SweepClosure(CMSCollector* collector, ConcurrentMarkSweepGeneration* g, | |
1742 CMSBitMap* bitMap, bool should_yield); | |
1743 ~SweepClosure(); | |
1744 | |
1745 size_t do_blk_careful(HeapWord* addr); | |
1746 }; | |
1747 | |
1748 // Closures related to weak references processing | |
1749 | |
1750 // During CMS' weak reference processing, this is a | |
1751 // work-routine/closure used to complete transitive | |
1752 // marking of objects as live after a certain point | |
1753 // in which an initial set has been completely accumulated. | |
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1754 // This closure is currently used both during the final |
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1755 // remark stop-world phase, as well as during the concurrent |
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1756 // precleaning of the discovered reference lists. |
0 | 1757 class CMSDrainMarkingStackClosure: public VoidClosure { |
1758 CMSCollector* _collector; | |
1759 MemRegion _span; | |
1760 CMSMarkStack* _mark_stack; | |
1761 CMSBitMap* _bit_map; | |
1762 CMSKeepAliveClosure* _keep_alive; | |
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1763 bool _concurrent_precleaning; |
0 | 1764 public: |
1765 CMSDrainMarkingStackClosure(CMSCollector* collector, MemRegion span, | |
1766 CMSBitMap* bit_map, CMSMarkStack* mark_stack, | |
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1767 CMSKeepAliveClosure* keep_alive, |
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1768 bool cpc): |
0 | 1769 _collector(collector), |
1770 _span(span), | |
1771 _bit_map(bit_map), | |
1772 _mark_stack(mark_stack), | |
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1773 _keep_alive(keep_alive), |
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1774 _concurrent_precleaning(cpc) { |
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1775 assert(_concurrent_precleaning == _keep_alive->concurrent_precleaning(), |
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1776 "Mismatch"); |
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1777 } |
0 | 1778 |
1779 void do_void(); | |
1780 }; | |
1781 | |
1782 // A parallel version of CMSDrainMarkingStackClosure above. | |
1783 class CMSParDrainMarkingStackClosure: public VoidClosure { | |
1784 CMSCollector* _collector; | |
1785 MemRegion _span; | |
1786 OopTaskQueue* _work_queue; | |
1787 CMSBitMap* _bit_map; | |
1788 CMSInnerParMarkAndPushClosure _mark_and_push; | |
1789 | |
1790 public: | |
1791 CMSParDrainMarkingStackClosure(CMSCollector* collector, | |
1792 MemRegion span, CMSBitMap* bit_map, | |
1793 OopTaskQueue* work_queue): | |
1794 _collector(collector), | |
1795 _span(span), | |
1796 _bit_map(bit_map), | |
1797 _work_queue(work_queue), | |
1798 _mark_and_push(collector, span, bit_map, work_queue) { } | |
1799 | |
1800 public: | |
1801 void trim_queue(uint max); | |
1802 void do_void(); | |
1803 }; | |
1804 | |
1805 // Allow yielding or short-circuiting of reference list | |
1806 // prelceaning work. | |
1807 class CMSPrecleanRefsYieldClosure: public YieldClosure { | |
1808 CMSCollector* _collector; | |
1809 void do_yield_work(); | |
1810 public: | |
1811 CMSPrecleanRefsYieldClosure(CMSCollector* collector): | |
1812 _collector(collector) {} | |
1813 virtual bool should_return(); | |
1814 }; | |
1815 | |
1816 | |
1817 // Convenience class that locks free list locks for given CMS collector | |
1818 class FreelistLocker: public StackObj { | |
1819 private: | |
1820 CMSCollector* _collector; | |
1821 public: | |
1822 FreelistLocker(CMSCollector* collector): | |
1823 _collector(collector) { | |
1824 _collector->getFreelistLocks(); | |
1825 } | |
1826 | |
1827 ~FreelistLocker() { | |
1828 _collector->releaseFreelistLocks(); | |
1829 } | |
1830 }; | |
1831 | |
1832 // Mark all dead objects in a given space. | |
1833 class MarkDeadObjectsClosure: public BlkClosure { | |
1834 const CMSCollector* _collector; | |
1835 const CompactibleFreeListSpace* _sp; | |
1836 CMSBitMap* _live_bit_map; | |
1837 CMSBitMap* _dead_bit_map; | |
1838 public: | |
1839 MarkDeadObjectsClosure(const CMSCollector* collector, | |
1840 const CompactibleFreeListSpace* sp, | |
1841 CMSBitMap *live_bit_map, | |
1842 CMSBitMap *dead_bit_map) : | |
1843 _collector(collector), | |
1844 _sp(sp), | |
1845 _live_bit_map(live_bit_map), | |
1846 _dead_bit_map(dead_bit_map) {} | |
1847 size_t do_blk(HeapWord* addr); | |
1848 }; |