Mercurial > hg > truffle
annotate src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.hpp @ 935:05f89f00a864
6798898: CMS: bugs related to class unloading
Summary: Override should_remember_klasses() and remember_klass() as needed.
Reviewed-by: ysr, jcoomes
author | jmasa |
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date | Mon, 24 Aug 2009 10:36:31 -0700 |
parents | fe1574da39fc |
children | e018e6884bd8 |
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 } |
798
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548 // Root scanning options for perm gen |
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549 int _roots_scanning_options; |
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550 int roots_scanning_options() const { return _roots_scanning_options; } |
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551 void add_root_scanning_option(int o) { _roots_scanning_options |= o; } |
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552 void remove_root_scanning_option(int o) { _roots_scanning_options &= ~o; } |
0 | 553 |
554 // Verification support | |
555 CMSBitMap _verification_mark_bm; | |
556 void verify_after_remark_work_1(); | |
557 void verify_after_remark_work_2(); | |
558 | |
559 // true if any verification flag is on. | |
560 bool _verifying; | |
561 bool verifying() const { return _verifying; } | |
562 void set_verifying(bool v) { _verifying = v; } | |
563 | |
564 // Collector policy | |
565 ConcurrentMarkSweepPolicy* _collector_policy; | |
566 ConcurrentMarkSweepPolicy* collector_policy() { return _collector_policy; } | |
567 | |
568 // Check whether the gc time limit has been | |
569 // exceeded and set the size policy flag | |
570 // appropriately. | |
571 void check_gc_time_limit(); | |
572 // XXX Move these to CMSStats ??? FIX ME !!! | |
573 elapsedTimer _sweep_timer; | |
574 AdaptivePaddedAverage _sweep_estimate; | |
575 | |
576 protected: | |
577 ConcurrentMarkSweepGeneration* _cmsGen; // old gen (CMS) | |
578 ConcurrentMarkSweepGeneration* _permGen; // perm gen | |
579 MemRegion _span; // span covering above two | |
580 CardTableRS* _ct; // card table | |
581 | |
582 // CMS marking support structures | |
583 CMSBitMap _markBitMap; | |
584 CMSBitMap _modUnionTable; | |
585 CMSMarkStack _markStack; | |
586 CMSMarkStack _revisitStack; // used to keep track of klassKlass objects | |
587 // to revisit | |
588 CMSBitMap _perm_gen_verify_bit_map; // Mark bit map for perm gen verification support. | |
589 | |
590 HeapWord* _restart_addr; // in support of marking stack overflow | |
591 void lower_restart_addr(HeapWord* low); | |
592 | |
593 // Counters in support of marking stack / work queue overflow handling: | |
594 // a non-zero value indicates certain types of overflow events during | |
595 // the current CMS cycle and could lead to stack resizing efforts at | |
596 // an opportune future time. | |
597 size_t _ser_pmc_preclean_ovflw; | |
598 size_t _ser_pmc_remark_ovflw; | |
599 size_t _par_pmc_remark_ovflw; | |
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600 size_t _ser_kac_preclean_ovflw; |
0 | 601 size_t _ser_kac_ovflw; |
602 size_t _par_kac_ovflw; | |
534 | 603 NOT_PRODUCT(ssize_t _num_par_pushes;) |
0 | 604 |
605 // ("Weak") Reference processing support | |
606 ReferenceProcessor* _ref_processor; | |
607 CMSIsAliveClosure _is_alive_closure; | |
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608 // keep this textually after _markBitMap and _span; c'tor dependency |
0 | 609 |
610 ConcurrentMarkSweepThread* _cmsThread; // the thread doing the work | |
611 ModUnionClosure _modUnionClosure; | |
612 ModUnionClosurePar _modUnionClosurePar; | |
613 | |
614 // CMS abstract state machine | |
615 // initial_state: Idling | |
616 // next_state(Idling) = {Marking} | |
617 // next_state(Marking) = {Precleaning, Sweeping} | |
618 // next_state(Precleaning) = {AbortablePreclean, FinalMarking} | |
619 // next_state(AbortablePreclean) = {FinalMarking} | |
620 // next_state(FinalMarking) = {Sweeping} | |
621 // next_state(Sweeping) = {Resizing} | |
622 // next_state(Resizing) = {Resetting} | |
623 // next_state(Resetting) = {Idling} | |
624 // The numeric values below are chosen so that: | |
625 // . _collectorState <= Idling == post-sweep && pre-mark | |
626 // . _collectorState in (Idling, Sweeping) == {initial,final}marking || | |
627 // precleaning || abortablePrecleanb | |
628 enum CollectorState { | |
629 Resizing = 0, | |
630 Resetting = 1, | |
631 Idling = 2, | |
632 InitialMarking = 3, | |
633 Marking = 4, | |
634 Precleaning = 5, | |
635 AbortablePreclean = 6, | |
636 FinalMarking = 7, | |
637 Sweeping = 8 | |
638 }; | |
639 static CollectorState _collectorState; | |
640 | |
641 // State related to prologue/epilogue invocation for my generations | |
642 bool _between_prologue_and_epilogue; | |
643 | |
644 // Signalling/State related to coordination between fore- and backgroud GC | |
645 // Note: When the baton has been passed from background GC to foreground GC, | |
646 // _foregroundGCIsActive is true and _foregroundGCShouldWait is false. | |
647 static bool _foregroundGCIsActive; // true iff foreground collector is active or | |
648 // wants to go active | |
649 static bool _foregroundGCShouldWait; // true iff background GC is active and has not | |
650 // yet passed the baton to the foreground GC | |
651 | |
652 // Support for CMSScheduleRemark (abortable preclean) | |
653 bool _abort_preclean; | |
654 bool _start_sampling; | |
655 | |
656 int _numYields; | |
657 size_t _numDirtyCards; | |
658 uint _sweepCount; | |
659 // number of full gc's since the last concurrent gc. | |
660 uint _full_gcs_since_conc_gc; | |
661 | |
662 // occupancy used for bootstrapping stats | |
663 double _bootstrap_occupancy; | |
664 | |
665 // timer | |
666 elapsedTimer _timer; | |
667 | |
668 // Timing, allocation and promotion statistics, used for scheduling. | |
669 CMSStats _stats; | |
670 | |
671 // Allocation limits installed in the young gen, used only in | |
672 // CMSIncrementalMode. When an allocation in the young gen would cross one of | |
673 // these limits, the cms generation is notified and the cms thread is started | |
674 // or stopped, respectively. | |
675 HeapWord* _icms_start_limit; | |
676 HeapWord* _icms_stop_limit; | |
677 | |
678 enum CMS_op_type { | |
679 CMS_op_checkpointRootsInitial, | |
680 CMS_op_checkpointRootsFinal | |
681 }; | |
682 | |
683 void do_CMS_operation(CMS_op_type op); | |
684 bool stop_world_and_do(CMS_op_type op); | |
685 | |
686 OopTaskQueueSet* task_queues() { return _task_queues; } | |
687 int* hash_seed(int i) { return &_hash_seed[i]; } | |
688 YieldingFlexibleWorkGang* conc_workers() { return _conc_workers; } | |
689 | |
690 // Support for parallelizing Eden rescan in CMS remark phase | |
691 void sample_eden(); // ... sample Eden space top | |
692 | |
693 private: | |
694 // Support for parallelizing young gen rescan in CMS remark phase | |
695 Generation* _young_gen; // the younger gen | |
696 HeapWord** _top_addr; // ... Top of Eden | |
697 HeapWord** _end_addr; // ... End of Eden | |
698 HeapWord** _eden_chunk_array; // ... Eden partitioning array | |
699 size_t _eden_chunk_index; // ... top (exclusive) of array | |
700 size_t _eden_chunk_capacity; // ... max entries in array | |
701 | |
702 // Support for parallelizing survivor space rescan | |
703 HeapWord** _survivor_chunk_array; | |
704 size_t _survivor_chunk_index; | |
705 size_t _survivor_chunk_capacity; | |
706 size_t* _cursor; | |
707 ChunkArray* _survivor_plab_array; | |
708 | |
709 // Support for marking stack overflow handling | |
710 bool take_from_overflow_list(size_t num, CMSMarkStack* to_stack); | |
711 bool par_take_from_overflow_list(size_t num, OopTaskQueue* to_work_q); | |
712 void push_on_overflow_list(oop p); | |
713 void par_push_on_overflow_list(oop p); | |
714 // the following is, obviously, not, in general, "MT-stable" | |
715 bool overflow_list_is_empty() const; | |
716 | |
717 void preserve_mark_if_necessary(oop p); | |
718 void par_preserve_mark_if_necessary(oop p); | |
719 void preserve_mark_work(oop p, markOop m); | |
720 void restore_preserved_marks_if_any(); | |
721 NOT_PRODUCT(bool no_preserved_marks() const;) | |
722 // in support of testing overflow code | |
723 NOT_PRODUCT(int _overflow_counter;) | |
724 NOT_PRODUCT(bool simulate_overflow();) // sequential | |
725 NOT_PRODUCT(bool par_simulate_overflow();) // MT version | |
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, | |
935 | 1793 CMSMarkStack* revisit_stack, |
0 | 1794 OopTaskQueue* work_queue): |
1795 _collector(collector), | |
1796 _span(span), | |
1797 _bit_map(bit_map), | |
1798 _work_queue(work_queue), | |
935 | 1799 _mark_and_push(collector, span, bit_map, revisit_stack, work_queue) { } |
0 | 1800 |
1801 public: | |
1802 void trim_queue(uint max); | |
1803 void do_void(); | |
1804 }; | |
1805 | |
1806 // Allow yielding or short-circuiting of reference list | |
1807 // prelceaning work. | |
1808 class CMSPrecleanRefsYieldClosure: public YieldClosure { | |
1809 CMSCollector* _collector; | |
1810 void do_yield_work(); | |
1811 public: | |
1812 CMSPrecleanRefsYieldClosure(CMSCollector* collector): | |
1813 _collector(collector) {} | |
1814 virtual bool should_return(); | |
1815 }; | |
1816 | |
1817 | |
1818 // Convenience class that locks free list locks for given CMS collector | |
1819 class FreelistLocker: public StackObj { | |
1820 private: | |
1821 CMSCollector* _collector; | |
1822 public: | |
1823 FreelistLocker(CMSCollector* collector): | |
1824 _collector(collector) { | |
1825 _collector->getFreelistLocks(); | |
1826 } | |
1827 | |
1828 ~FreelistLocker() { | |
1829 _collector->releaseFreelistLocks(); | |
1830 } | |
1831 }; | |
1832 | |
1833 // Mark all dead objects in a given space. | |
1834 class MarkDeadObjectsClosure: public BlkClosure { | |
1835 const CMSCollector* _collector; | |
1836 const CompactibleFreeListSpace* _sp; | |
1837 CMSBitMap* _live_bit_map; | |
1838 CMSBitMap* _dead_bit_map; | |
1839 public: | |
1840 MarkDeadObjectsClosure(const CMSCollector* collector, | |
1841 const CompactibleFreeListSpace* sp, | |
1842 CMSBitMap *live_bit_map, | |
1843 CMSBitMap *dead_bit_map) : | |
1844 _collector(collector), | |
1845 _sp(sp), | |
1846 _live_bit_map(live_bit_map), | |
1847 _dead_bit_map(dead_bit_map) {} | |
1848 size_t do_blk(HeapWord* addr); | |
1849 }; |