Mercurial > hg > truffle
annotate src/share/vm/gc_implementation/g1/concurrentMark.hpp @ 1023:11d4857fe5e1
6888619: G1: too many guarantees in concurrent marking
Summary: change more guarantees in concurrent marking into asserts.
Reviewed-by: apetrusenko, iveresov
author | tonyp |
---|---|
date | Wed, 07 Oct 2009 10:09:57 -0400 |
parents | 035d2e036a9b |
children | 6270f80a7331 |
rev | line source |
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342 | 1 /* |
579 | 2 * Copyright 2001-2009 Sun Microsystems, Inc. All Rights Reserved. |
342 | 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 class G1CollectedHeap; | |
26 class CMTask; | |
27 typedef GenericTaskQueue<oop> CMTaskQueue; | |
28 typedef GenericTaskQueueSet<oop> CMTaskQueueSet; | |
29 | |
30 // A generic CM bit map. This is essentially a wrapper around the BitMap | |
31 // class, with one bit per (1<<_shifter) HeapWords. | |
32 | |
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33 class CMBitMapRO VALUE_OBJ_CLASS_SPEC { |
342 | 34 protected: |
35 HeapWord* _bmStartWord; // base address of range covered by map | |
36 size_t _bmWordSize; // map size (in #HeapWords covered) | |
37 const int _shifter; // map to char or bit | |
38 VirtualSpace _virtual_space; // underlying the bit map | |
39 BitMap _bm; // the bit map itself | |
40 | |
41 public: | |
42 // constructor | |
43 CMBitMapRO(ReservedSpace rs, int shifter); | |
44 | |
45 enum { do_yield = true }; | |
46 | |
47 // inquiries | |
48 HeapWord* startWord() const { return _bmStartWord; } | |
49 size_t sizeInWords() const { return _bmWordSize; } | |
50 // the following is one past the last word in space | |
51 HeapWord* endWord() const { return _bmStartWord + _bmWordSize; } | |
52 | |
53 // read marks | |
54 | |
55 bool isMarked(HeapWord* addr) const { | |
56 assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize), | |
57 "outside underlying space?"); | |
58 return _bm.at(heapWordToOffset(addr)); | |
59 } | |
60 | |
61 // iteration | |
62 bool iterate(BitMapClosure* cl) { return _bm.iterate(cl); } | |
63 bool iterate(BitMapClosure* cl, MemRegion mr); | |
64 | |
65 // Return the address corresponding to the next marked bit at or after | |
66 // "addr", and before "limit", if "limit" is non-NULL. If there is no | |
67 // such bit, returns "limit" if that is non-NULL, or else "endWord()". | |
68 HeapWord* getNextMarkedWordAddress(HeapWord* addr, | |
69 HeapWord* limit = NULL) const; | |
70 // Return the address corresponding to the next unmarked bit at or after | |
71 // "addr", and before "limit", if "limit" is non-NULL. If there is no | |
72 // such bit, returns "limit" if that is non-NULL, or else "endWord()". | |
73 HeapWord* getNextUnmarkedWordAddress(HeapWord* addr, | |
74 HeapWord* limit = NULL) const; | |
75 | |
76 // conversion utilities | |
77 // XXX Fix these so that offsets are size_t's... | |
78 HeapWord* offsetToHeapWord(size_t offset) const { | |
79 return _bmStartWord + (offset << _shifter); | |
80 } | |
81 size_t heapWordToOffset(HeapWord* addr) const { | |
82 return pointer_delta(addr, _bmStartWord) >> _shifter; | |
83 } | |
84 int heapWordDiffToOffsetDiff(size_t diff) const; | |
85 HeapWord* nextWord(HeapWord* addr) { | |
86 return offsetToHeapWord(heapWordToOffset(addr) + 1); | |
87 } | |
88 | |
89 void mostly_disjoint_range_union(BitMap* from_bitmap, | |
90 size_t from_start_index, | |
91 HeapWord* to_start_word, | |
92 size_t word_num); | |
93 | |
94 // debugging | |
95 NOT_PRODUCT(bool covers(ReservedSpace rs) const;) | |
96 }; | |
97 | |
98 class CMBitMap : public CMBitMapRO { | |
99 | |
100 public: | |
101 // constructor | |
102 CMBitMap(ReservedSpace rs, int shifter) : | |
103 CMBitMapRO(rs, shifter) {} | |
104 | |
105 // write marks | |
106 void mark(HeapWord* addr) { | |
107 assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize), | |
108 "outside underlying space?"); | |
109 _bm.at_put(heapWordToOffset(addr), true); | |
110 } | |
111 void clear(HeapWord* addr) { | |
112 assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize), | |
113 "outside underlying space?"); | |
114 _bm.at_put(heapWordToOffset(addr), false); | |
115 } | |
116 bool parMark(HeapWord* addr) { | |
117 assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize), | |
118 "outside underlying space?"); | |
119 return _bm.par_at_put(heapWordToOffset(addr), true); | |
120 } | |
121 bool parClear(HeapWord* addr) { | |
122 assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize), | |
123 "outside underlying space?"); | |
124 return _bm.par_at_put(heapWordToOffset(addr), false); | |
125 } | |
126 void markRange(MemRegion mr); | |
127 void clearAll(); | |
128 void clearRange(MemRegion mr); | |
129 | |
130 // Starting at the bit corresponding to "addr" (inclusive), find the next | |
131 // "1" bit, if any. This bit starts some run of consecutive "1"'s; find | |
132 // the end of this run (stopping at "end_addr"). Return the MemRegion | |
133 // covering from the start of the region corresponding to the first bit | |
134 // of the run to the end of the region corresponding to the last bit of | |
135 // the run. If there is no "1" bit at or after "addr", return an empty | |
136 // MemRegion. | |
137 MemRegion getAndClearMarkedRegion(HeapWord* addr, HeapWord* end_addr); | |
138 }; | |
139 | |
140 // Represents a marking stack used by the CM collector. | |
141 // Ideally this should be GrowableArray<> just like MSC's marking stack(s). | |
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142 class CMMarkStack VALUE_OBJ_CLASS_SPEC { |
342 | 143 ConcurrentMark* _cm; |
144 oop* _base; // bottom of stack | |
145 jint _index; // one more than last occupied index | |
146 jint _capacity; // max #elements | |
147 jint _oops_do_bound; // Number of elements to include in next iteration. | |
148 NOT_PRODUCT(jint _max_depth;) // max depth plumbed during run | |
149 | |
150 bool _overflow; | |
151 DEBUG_ONLY(bool _drain_in_progress;) | |
152 DEBUG_ONLY(bool _drain_in_progress_yields;) | |
153 | |
154 public: | |
155 CMMarkStack(ConcurrentMark* cm); | |
156 ~CMMarkStack(); | |
157 | |
158 void allocate(size_t size); | |
159 | |
160 oop pop() { | |
161 if (!isEmpty()) { | |
162 return _base[--_index] ; | |
163 } | |
164 return NULL; | |
165 } | |
166 | |
167 // If overflow happens, don't do the push, and record the overflow. | |
168 // *Requires* that "ptr" is already marked. | |
169 void push(oop ptr) { | |
170 if (isFull()) { | |
171 // Record overflow. | |
172 _overflow = true; | |
173 return; | |
174 } else { | |
175 _base[_index++] = ptr; | |
176 NOT_PRODUCT(_max_depth = MAX2(_max_depth, _index)); | |
177 } | |
178 } | |
179 // Non-block impl. Note: concurrency is allowed only with other | |
180 // "par_push" operations, not with "pop" or "drain". We would need | |
181 // parallel versions of them if such concurrency was desired. | |
182 void par_push(oop ptr); | |
183 | |
184 // Pushes the first "n" elements of "ptr_arr" on the stack. | |
185 // Non-block impl. Note: concurrency is allowed only with other | |
186 // "par_adjoin_arr" or "push" operations, not with "pop" or "drain". | |
187 void par_adjoin_arr(oop* ptr_arr, int n); | |
188 | |
189 // Pushes the first "n" elements of "ptr_arr" on the stack. | |
190 // Locking impl: concurrency is allowed only with | |
191 // "par_push_arr" and/or "par_pop_arr" operations, which use the same | |
192 // locking strategy. | |
193 void par_push_arr(oop* ptr_arr, int n); | |
194 | |
195 // If returns false, the array was empty. Otherwise, removes up to "max" | |
196 // elements from the stack, and transfers them to "ptr_arr" in an | |
197 // unspecified order. The actual number transferred is given in "n" ("n | |
198 // == 0" is deliberately redundant with the return value.) Locking impl: | |
199 // concurrency is allowed only with "par_push_arr" and/or "par_pop_arr" | |
200 // operations, which use the same locking strategy. | |
201 bool par_pop_arr(oop* ptr_arr, int max, int* n); | |
202 | |
203 // Drain the mark stack, applying the given closure to all fields of | |
204 // objects on the stack. (That is, continue until the stack is empty, | |
205 // even if closure applications add entries to the stack.) The "bm" | |
206 // argument, if non-null, may be used to verify that only marked objects | |
207 // are on the mark stack. If "yield_after" is "true", then the | |
208 // concurrent marker performing the drain offers to yield after | |
209 // processing each object. If a yield occurs, stops the drain operation | |
210 // and returns false. Otherwise, returns true. | |
211 template<class OopClosureClass> | |
212 bool drain(OopClosureClass* cl, CMBitMap* bm, bool yield_after = false); | |
213 | |
214 bool isEmpty() { return _index == 0; } | |
215 bool isFull() { return _index == _capacity; } | |
216 int maxElems() { return _capacity; } | |
217 | |
218 bool overflow() { return _overflow; } | |
219 void clear_overflow() { _overflow = false; } | |
220 | |
221 int size() { return _index; } | |
222 | |
223 void setEmpty() { _index = 0; clear_overflow(); } | |
224 | |
225 // Record the current size; a subsequent "oops_do" will iterate only over | |
226 // indices valid at the time of this call. | |
227 void set_oops_do_bound(jint bound = -1) { | |
228 if (bound == -1) { | |
229 _oops_do_bound = _index; | |
230 } else { | |
231 _oops_do_bound = bound; | |
232 } | |
233 } | |
234 jint oops_do_bound() { return _oops_do_bound; } | |
235 // iterate over the oops in the mark stack, up to the bound recorded via | |
236 // the call above. | |
237 void oops_do(OopClosure* f); | |
238 }; | |
239 | |
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240 class CMRegionStack VALUE_OBJ_CLASS_SPEC { |
342 | 241 MemRegion* _base; |
242 jint _capacity; | |
243 jint _index; | |
244 jint _oops_do_bound; | |
245 bool _overflow; | |
246 public: | |
247 CMRegionStack(); | |
248 ~CMRegionStack(); | |
249 void allocate(size_t size); | |
250 | |
251 // This is lock-free; assumes that it will only be called in parallel | |
252 // with other "push" operations (no pops). | |
253 void push(MemRegion mr); | |
254 | |
255 // Lock-free; assumes that it will only be called in parallel | |
256 // with other "pop" operations (no pushes). | |
257 MemRegion pop(); | |
258 | |
259 bool isEmpty() { return _index == 0; } | |
260 bool isFull() { return _index == _capacity; } | |
261 | |
262 bool overflow() { return _overflow; } | |
263 void clear_overflow() { _overflow = false; } | |
264 | |
265 int size() { return _index; } | |
266 | |
267 // It iterates over the entries in the region stack and it | |
268 // invalidates (i.e. assigns MemRegion()) the ones that point to | |
269 // regions in the collection set. | |
270 bool invalidate_entries_into_cset(); | |
271 | |
272 // This gives an upper bound up to which the iteration in | |
273 // invalidate_entries_into_cset() will reach. This prevents | |
274 // newly-added entries to be unnecessarily scanned. | |
275 void set_oops_do_bound() { | |
276 _oops_do_bound = _index; | |
277 } | |
278 | |
279 void setEmpty() { _index = 0; clear_overflow(); } | |
280 }; | |
281 | |
282 // this will enable a variety of different statistics per GC task | |
283 #define _MARKING_STATS_ 0 | |
284 // this will enable the higher verbose levels | |
285 #define _MARKING_VERBOSE_ 0 | |
286 | |
287 #if _MARKING_STATS_ | |
288 #define statsOnly(statement) \ | |
289 do { \ | |
290 statement ; \ | |
291 } while (0) | |
292 #else // _MARKING_STATS_ | |
293 #define statsOnly(statement) \ | |
294 do { \ | |
295 } while (0) | |
296 #endif // _MARKING_STATS_ | |
297 | |
298 typedef enum { | |
299 no_verbose = 0, // verbose turned off | |
300 stats_verbose, // only prints stats at the end of marking | |
301 low_verbose, // low verbose, mostly per region and per major event | |
302 medium_verbose, // a bit more detailed than low | |
303 high_verbose // per object verbose | |
304 } CMVerboseLevel; | |
305 | |
306 | |
307 class ConcurrentMarkThread; | |
308 | |
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309 class ConcurrentMark: public CHeapObj { |
342 | 310 friend class ConcurrentMarkThread; |
311 friend class CMTask; | |
312 friend class CMBitMapClosure; | |
313 friend class CSMarkOopClosure; | |
314 friend class CMGlobalObjectClosure; | |
315 friend class CMRemarkTask; | |
316 friend class CMConcurrentMarkingTask; | |
317 friend class G1ParNoteEndTask; | |
318 friend class CalcLiveObjectsClosure; | |
319 | |
320 protected: | |
321 ConcurrentMarkThread* _cmThread; // the thread doing the work | |
322 G1CollectedHeap* _g1h; // the heap. | |
323 size_t _parallel_marking_threads; // the number of marking | |
324 // threads we'll use | |
325 double _sleep_factor; // how much we have to sleep, with | |
326 // respect to the work we just did, to | |
327 // meet the marking overhead goal | |
328 double _marking_task_overhead; // marking target overhead for | |
329 // a single task | |
330 | |
331 // same as the two above, but for the cleanup task | |
332 double _cleanup_sleep_factor; | |
333 double _cleanup_task_overhead; | |
334 | |
335 // Stuff related to age cohort processing. | |
336 struct ParCleanupThreadState { | |
337 char _pre[64]; | |
338 UncleanRegionList list; | |
339 char _post[64]; | |
340 }; | |
341 ParCleanupThreadState** _par_cleanup_thread_state; | |
342 | |
343 // CMS marking support structures | |
344 CMBitMap _markBitMap1; | |
345 CMBitMap _markBitMap2; | |
346 CMBitMapRO* _prevMarkBitMap; // completed mark bitmap | |
347 CMBitMap* _nextMarkBitMap; // under-construction mark bitmap | |
348 bool _at_least_one_mark_complete; | |
349 | |
350 BitMap _region_bm; | |
351 BitMap _card_bm; | |
352 | |
353 // Heap bounds | |
354 HeapWord* _heap_start; | |
355 HeapWord* _heap_end; | |
356 | |
357 // For gray objects | |
358 CMMarkStack _markStack; // Grey objects behind global finger. | |
359 CMRegionStack _regionStack; // Grey regions behind global finger. | |
360 HeapWord* volatile _finger; // the global finger, region aligned, | |
361 // always points to the end of the | |
362 // last claimed region | |
363 | |
364 // marking tasks | |
365 size_t _max_task_num; // maximum task number | |
366 size_t _active_tasks; // task num currently active | |
367 CMTask** _tasks; // task queue array (max_task_num len) | |
368 CMTaskQueueSet* _task_queues; // task queue set | |
369 ParallelTaskTerminator _terminator; // for termination | |
370 | |
371 // Two sync barriers that are used to synchronise tasks when an | |
372 // overflow occurs. The algorithm is the following. All tasks enter | |
373 // the first one to ensure that they have all stopped manipulating | |
374 // the global data structures. After they exit it, they re-initialise | |
375 // their data structures and task 0 re-initialises the global data | |
376 // structures. Then, they enter the second sync barrier. This | |
377 // ensure, that no task starts doing work before all data | |
378 // structures (local and global) have been re-initialised. When they | |
379 // exit it, they are free to start working again. | |
380 WorkGangBarrierSync _first_overflow_barrier_sync; | |
381 WorkGangBarrierSync _second_overflow_barrier_sync; | |
382 | |
383 | |
384 // this is set by any task, when an overflow on the global data | |
385 // structures is detected. | |
386 volatile bool _has_overflown; | |
387 // true: marking is concurrent, false: we're in remark | |
388 volatile bool _concurrent; | |
389 // set at the end of a Full GC so that marking aborts | |
390 volatile bool _has_aborted; | |
391 // used when remark aborts due to an overflow to indicate that | |
392 // another concurrent marking phase should start | |
393 volatile bool _restart_for_overflow; | |
394 | |
395 // This is true from the very start of concurrent marking until the | |
396 // point when all the tasks complete their work. It is really used | |
397 // to determine the points between the end of concurrent marking and | |
398 // time of remark. | |
399 volatile bool _concurrent_marking_in_progress; | |
400 | |
401 // verbose level | |
402 CMVerboseLevel _verbose_level; | |
403 | |
404 // These two fields are used to implement the optimisation that | |
405 // avoids pushing objects on the global/region stack if there are | |
406 // no collection set regions above the lowest finger. | |
407 | |
408 // This is the lowest finger (among the global and local fingers), | |
409 // which is calculated before a new collection set is chosen. | |
410 HeapWord* _min_finger; | |
411 // If this flag is true, objects/regions that are marked below the | |
412 // finger should be pushed on the stack(s). If this is flag is | |
413 // false, it is safe not to push them on the stack(s). | |
414 bool _should_gray_objects; | |
415 | |
416 // All of these times are in ms. | |
417 NumberSeq _init_times; | |
418 NumberSeq _remark_times; | |
419 NumberSeq _remark_mark_times; | |
420 NumberSeq _remark_weak_ref_times; | |
421 NumberSeq _cleanup_times; | |
422 double _total_counting_time; | |
423 double _total_rs_scrub_time; | |
424 | |
425 double* _accum_task_vtime; // accumulated task vtime | |
426 | |
427 WorkGang* _parallel_workers; | |
428 | |
429 void weakRefsWork(bool clear_all_soft_refs); | |
430 | |
431 void swapMarkBitMaps(); | |
432 | |
433 // It resets the global marking data structures, as well as the | |
434 // task local ones; should be called during initial mark. | |
435 void reset(); | |
436 // It resets all the marking data structures. | |
437 void clear_marking_state(); | |
438 | |
439 // It should be called to indicate which phase we're in (concurrent | |
440 // mark or remark) and how many threads are currently active. | |
441 void set_phase(size_t active_tasks, bool concurrent); | |
442 // We do this after we're done with marking so that the marking data | |
443 // structures are initialised to a sensible and predictable state. | |
444 void set_non_marking_state(); | |
445 | |
446 // prints all gathered CM-related statistics | |
447 void print_stats(); | |
448 | |
449 // accessor methods | |
450 size_t parallel_marking_threads() { return _parallel_marking_threads; } | |
451 double sleep_factor() { return _sleep_factor; } | |
452 double marking_task_overhead() { return _marking_task_overhead;} | |
453 double cleanup_sleep_factor() { return _cleanup_sleep_factor; } | |
454 double cleanup_task_overhead() { return _cleanup_task_overhead;} | |
455 | |
456 HeapWord* finger() { return _finger; } | |
457 bool concurrent() { return _concurrent; } | |
458 size_t active_tasks() { return _active_tasks; } | |
459 ParallelTaskTerminator* terminator() { return &_terminator; } | |
460 | |
461 // It claims the next available region to be scanned by a marking | |
462 // task. It might return NULL if the next region is empty or we have | |
463 // run out of regions. In the latter case, out_of_regions() | |
464 // determines whether we've really run out of regions or the task | |
465 // should call claim_region() again. This might seem a bit | |
466 // awkward. Originally, the code was written so that claim_region() | |
467 // either successfully returned with a non-empty region or there | |
468 // were no more regions to be claimed. The problem with this was | |
469 // that, in certain circumstances, it iterated over large chunks of | |
470 // the heap finding only empty regions and, while it was working, it | |
471 // was preventing the calling task to call its regular clock | |
472 // method. So, this way, each task will spend very little time in | |
473 // claim_region() and is allowed to call the regular clock method | |
474 // frequently. | |
475 HeapRegion* claim_region(int task); | |
476 | |
477 // It determines whether we've run out of regions to scan. | |
478 bool out_of_regions() { return _finger == _heap_end; } | |
479 | |
480 // Returns the task with the given id | |
481 CMTask* task(int id) { | |
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482 assert(0 <= id && id < (int) _active_tasks, |
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483 "task id not within active bounds"); |
342 | 484 return _tasks[id]; |
485 } | |
486 | |
487 // Returns the task queue with the given id | |
488 CMTaskQueue* task_queue(int id) { | |
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489 assert(0 <= id && id < (int) _active_tasks, |
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490 "task queue id not within active bounds"); |
342 | 491 return (CMTaskQueue*) _task_queues->queue(id); |
492 } | |
493 | |
494 // Returns the task queue set | |
495 CMTaskQueueSet* task_queues() { return _task_queues; } | |
496 | |
497 // Access / manipulation of the overflow flag which is set to | |
498 // indicate that the global stack or region stack has overflown | |
499 bool has_overflown() { return _has_overflown; } | |
500 void set_has_overflown() { _has_overflown = true; } | |
501 void clear_has_overflown() { _has_overflown = false; } | |
502 | |
503 bool has_aborted() { return _has_aborted; } | |
504 bool restart_for_overflow() { return _restart_for_overflow; } | |
505 | |
506 // Methods to enter the two overflow sync barriers | |
507 void enter_first_sync_barrier(int task_num); | |
508 void enter_second_sync_barrier(int task_num); | |
509 | |
510 public: | |
511 // Manipulation of the global mark stack. | |
512 // Notice that the first mark_stack_push is CAS-based, whereas the | |
513 // two below are Mutex-based. This is OK since the first one is only | |
514 // called during evacuation pauses and doesn't compete with the | |
515 // other two (which are called by the marking tasks during | |
516 // concurrent marking or remark). | |
517 bool mark_stack_push(oop p) { | |
518 _markStack.par_push(p); | |
519 if (_markStack.overflow()) { | |
520 set_has_overflown(); | |
521 return false; | |
522 } | |
523 return true; | |
524 } | |
525 bool mark_stack_push(oop* arr, int n) { | |
526 _markStack.par_push_arr(arr, n); | |
527 if (_markStack.overflow()) { | |
528 set_has_overflown(); | |
529 return false; | |
530 } | |
531 return true; | |
532 } | |
533 void mark_stack_pop(oop* arr, int max, int* n) { | |
534 _markStack.par_pop_arr(arr, max, n); | |
535 } | |
536 size_t mark_stack_size() { return _markStack.size(); } | |
537 size_t partial_mark_stack_size_target() { return _markStack.maxElems()/3; } | |
538 bool mark_stack_overflow() { return _markStack.overflow(); } | |
539 bool mark_stack_empty() { return _markStack.isEmpty(); } | |
540 | |
541 // Manipulation of the region stack | |
542 bool region_stack_push(MemRegion mr) { | |
543 _regionStack.push(mr); | |
544 if (_regionStack.overflow()) { | |
545 set_has_overflown(); | |
546 return false; | |
547 } | |
548 return true; | |
549 } | |
550 MemRegion region_stack_pop() { return _regionStack.pop(); } | |
551 int region_stack_size() { return _regionStack.size(); } | |
552 bool region_stack_overflow() { return _regionStack.overflow(); } | |
553 bool region_stack_empty() { return _regionStack.isEmpty(); } | |
554 | |
555 bool concurrent_marking_in_progress() { | |
556 return _concurrent_marking_in_progress; | |
557 } | |
558 void set_concurrent_marking_in_progress() { | |
559 _concurrent_marking_in_progress = true; | |
560 } | |
561 void clear_concurrent_marking_in_progress() { | |
562 _concurrent_marking_in_progress = false; | |
563 } | |
564 | |
565 void update_accum_task_vtime(int i, double vtime) { | |
566 _accum_task_vtime[i] += vtime; | |
567 } | |
568 | |
569 double all_task_accum_vtime() { | |
570 double ret = 0.0; | |
571 for (int i = 0; i < (int)_max_task_num; ++i) | |
572 ret += _accum_task_vtime[i]; | |
573 return ret; | |
574 } | |
575 | |
576 // Attempts to steal an object from the task queues of other tasks | |
577 bool try_stealing(int task_num, int* hash_seed, oop& obj) { | |
578 return _task_queues->steal(task_num, hash_seed, obj); | |
579 } | |
580 | |
581 // It grays an object by first marking it. Then, if it's behind the | |
582 // global finger, it also pushes it on the global stack. | |
583 void deal_with_reference(oop obj); | |
584 | |
585 ConcurrentMark(ReservedSpace rs, int max_regions); | |
586 ~ConcurrentMark(); | |
587 ConcurrentMarkThread* cmThread() { return _cmThread; } | |
588 | |
589 CMBitMapRO* prevMarkBitMap() const { return _prevMarkBitMap; } | |
590 CMBitMap* nextMarkBitMap() const { return _nextMarkBitMap; } | |
591 | |
592 // The following three are interaction between CM and | |
593 // G1CollectedHeap | |
594 | |
595 // This notifies CM that a root during initial-mark needs to be | |
596 // grayed and it's MT-safe. Currently, we just mark it. But, in the | |
597 // future, we can experiment with pushing it on the stack and we can | |
598 // do this without changing G1CollectedHeap. | |
599 void grayRoot(oop p); | |
600 // It's used during evacuation pauses to gray a region, if | |
601 // necessary, and it's MT-safe. It assumes that the caller has | |
602 // marked any objects on that region. If _should_gray_objects is | |
603 // true and we're still doing concurrent marking, the region is | |
604 // pushed on the region stack, if it is located below the global | |
605 // finger, otherwise we do nothing. | |
606 void grayRegionIfNecessary(MemRegion mr); | |
607 // It's used during evacuation pauses to mark and, if necessary, | |
608 // gray a single object and it's MT-safe. It assumes the caller did | |
609 // not mark the object. If _should_gray_objects is true and we're | |
610 // still doing concurrent marking, the objects is pushed on the | |
611 // global stack, if it is located below the global finger, otherwise | |
612 // we do nothing. | |
613 void markAndGrayObjectIfNecessary(oop p); | |
614 | |
615 // This iterates over the bitmap of the previous marking and prints | |
616 // out all objects that are marked on the bitmap and indicates | |
617 // whether what they point to is also marked or not. | |
618 void print_prev_bitmap_reachable(); | |
619 | |
620 // Clear the next marking bitmap (will be called concurrently). | |
621 void clearNextBitmap(); | |
622 | |
623 // main CMS steps and related support | |
624 void checkpointRootsInitial(); | |
625 | |
626 // These two do the work that needs to be done before and after the | |
627 // initial root checkpoint. Since this checkpoint can be done at two | |
628 // different points (i.e. an explicit pause or piggy-backed on a | |
629 // young collection), then it's nice to be able to easily share the | |
630 // pre/post code. It might be the case that we can put everything in | |
631 // the post method. TP | |
632 void checkpointRootsInitialPre(); | |
633 void checkpointRootsInitialPost(); | |
634 | |
635 // Do concurrent phase of marking, to a tentative transitive closure. | |
636 void markFromRoots(); | |
637 | |
638 // Process all unprocessed SATB buffers. It is called at the | |
639 // beginning of an evacuation pause. | |
640 void drainAllSATBBuffers(); | |
641 | |
642 void checkpointRootsFinal(bool clear_all_soft_refs); | |
643 void checkpointRootsFinalWork(); | |
644 void calcDesiredRegions(); | |
645 void cleanup(); | |
646 void completeCleanup(); | |
647 | |
648 // Mark in the previous bitmap. NB: this is usually read-only, so use | |
649 // this carefully! | |
650 void markPrev(oop p); | |
651 void clear(oop p); | |
652 // Clears marks for all objects in the given range, for both prev and | |
653 // next bitmaps. NB: the previous bitmap is usually read-only, so use | |
654 // this carefully! | |
655 void clearRangeBothMaps(MemRegion mr); | |
656 | |
657 // Record the current top of the mark and region stacks; a | |
658 // subsequent oops_do() on the mark stack and | |
659 // invalidate_entries_into_cset() on the region stack will iterate | |
660 // only over indices valid at the time of this call. | |
661 void set_oops_do_bound() { | |
662 _markStack.set_oops_do_bound(); | |
663 _regionStack.set_oops_do_bound(); | |
664 } | |
665 // Iterate over the oops in the mark stack and all local queues. It | |
666 // also calls invalidate_entries_into_cset() on the region stack. | |
667 void oops_do(OopClosure* f); | |
668 // It is called at the end of an evacuation pause during marking so | |
669 // that CM is notified of where the new end of the heap is. It | |
670 // doesn't do anything if concurrent_marking_in_progress() is false, | |
671 // unless the force parameter is true. | |
672 void update_g1_committed(bool force = false); | |
673 | |
674 void complete_marking_in_collection_set(); | |
675 | |
676 // It indicates that a new collection set is being chosen. | |
677 void newCSet(); | |
678 // It registers a collection set heap region with CM. This is used | |
679 // to determine whether any heap regions are located above the finger. | |
680 void registerCSetRegion(HeapRegion* hr); | |
681 | |
682 // Returns "true" if at least one mark has been completed. | |
683 bool at_least_one_mark_complete() { return _at_least_one_mark_complete; } | |
684 | |
685 bool isMarked(oop p) const { | |
686 assert(p != NULL && p->is_oop(), "expected an oop"); | |
687 HeapWord* addr = (HeapWord*)p; | |
688 assert(addr >= _nextMarkBitMap->startWord() || | |
689 addr < _nextMarkBitMap->endWord(), "in a region"); | |
690 | |
691 return _nextMarkBitMap->isMarked(addr); | |
692 } | |
693 | |
694 inline bool not_yet_marked(oop p) const; | |
695 | |
696 // XXX Debug code | |
697 bool containing_card_is_marked(void* p); | |
698 bool containing_cards_are_marked(void* start, void* last); | |
699 | |
700 bool isPrevMarked(oop p) const { | |
701 assert(p != NULL && p->is_oop(), "expected an oop"); | |
702 HeapWord* addr = (HeapWord*)p; | |
703 assert(addr >= _prevMarkBitMap->startWord() || | |
704 addr < _prevMarkBitMap->endWord(), "in a region"); | |
705 | |
706 return _prevMarkBitMap->isMarked(addr); | |
707 } | |
708 | |
709 inline bool do_yield_check(int worker_i = 0); | |
710 inline bool should_yield(); | |
711 | |
712 // Called to abort the marking cycle after a Full GC takes palce. | |
713 void abort(); | |
714 | |
715 // This prints the global/local fingers. It is used for debugging. | |
716 NOT_PRODUCT(void print_finger();) | |
717 | |
718 void print_summary_info(); | |
719 | |
1019 | 720 void print_worker_threads_on(outputStream* st) const; |
721 | |
342 | 722 // The following indicate whether a given verbose level has been |
723 // set. Notice that anything above stats is conditional to | |
724 // _MARKING_VERBOSE_ having been set to 1 | |
725 bool verbose_stats() | |
726 { return _verbose_level >= stats_verbose; } | |
727 bool verbose_low() | |
728 { return _MARKING_VERBOSE_ && _verbose_level >= low_verbose; } | |
729 bool verbose_medium() | |
730 { return _MARKING_VERBOSE_ && _verbose_level >= medium_verbose; } | |
731 bool verbose_high() | |
732 { return _MARKING_VERBOSE_ && _verbose_level >= high_verbose; } | |
733 }; | |
734 | |
735 // A class representing a marking task. | |
736 class CMTask : public TerminatorTerminator { | |
737 private: | |
738 enum PrivateConstants { | |
739 // the regular clock call is called once the scanned words reaches | |
740 // this limit | |
741 words_scanned_period = 12*1024, | |
742 // the regular clock call is called once the number of visited | |
743 // references reaches this limit | |
744 refs_reached_period = 384, | |
745 // initial value for the hash seed, used in the work stealing code | |
746 init_hash_seed = 17, | |
747 // how many entries will be transferred between global stack and | |
748 // local queues | |
749 global_stack_transfer_size = 16 | |
750 }; | |
751 | |
752 int _task_id; | |
753 G1CollectedHeap* _g1h; | |
754 ConcurrentMark* _cm; | |
755 CMBitMap* _nextMarkBitMap; | |
756 // the task queue of this task | |
757 CMTaskQueue* _task_queue; | |
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758 private: |
342 | 759 // the task queue set---needed for stealing |
760 CMTaskQueueSet* _task_queues; | |
761 // indicates whether the task has been claimed---this is only for | |
762 // debugging purposes | |
763 bool _claimed; | |
764 | |
765 // number of calls to this task | |
766 int _calls; | |
767 | |
768 // when the virtual timer reaches this time, the marking step should | |
769 // exit | |
770 double _time_target_ms; | |
771 // the start time of the current marking step | |
772 double _start_time_ms; | |
773 | |
774 // the oop closure used for iterations over oops | |
775 OopClosure* _oop_closure; | |
776 | |
777 // the region this task is scanning, NULL if we're not scanning any | |
778 HeapRegion* _curr_region; | |
779 // the local finger of this task, NULL if we're not scanning a region | |
780 HeapWord* _finger; | |
781 // limit of the region this task is scanning, NULL if we're not scanning one | |
782 HeapWord* _region_limit; | |
783 | |
784 // This is used only when we scan regions popped from the region | |
785 // stack. It records what the last object on such a region we | |
786 // scanned was. It is used to ensure that, if we abort region | |
787 // iteration, we do not rescan the first part of the region. This | |
788 // should be NULL when we're not scanning a region from the region | |
789 // stack. | |
790 HeapWord* _region_finger; | |
791 | |
792 // the number of words this task has scanned | |
793 size_t _words_scanned; | |
794 // When _words_scanned reaches this limit, the regular clock is | |
795 // called. Notice that this might be decreased under certain | |
796 // circumstances (i.e. when we believe that we did an expensive | |
797 // operation). | |
798 size_t _words_scanned_limit; | |
799 // the initial value of _words_scanned_limit (i.e. what it was | |
800 // before it was decreased). | |
801 size_t _real_words_scanned_limit; | |
802 | |
803 // the number of references this task has visited | |
804 size_t _refs_reached; | |
805 // When _refs_reached reaches this limit, the regular clock is | |
806 // called. Notice this this might be decreased under certain | |
807 // circumstances (i.e. when we believe that we did an expensive | |
808 // operation). | |
809 size_t _refs_reached_limit; | |
810 // the initial value of _refs_reached_limit (i.e. what it was before | |
811 // it was decreased). | |
812 size_t _real_refs_reached_limit; | |
813 | |
814 // used by the work stealing stuff | |
815 int _hash_seed; | |
816 // if this is true, then the task has aborted for some reason | |
817 bool _has_aborted; | |
818 // set when the task aborts because it has met its time quota | |
819 bool _has_aborted_timed_out; | |
820 // true when we're draining SATB buffers; this avoids the task | |
821 // aborting due to SATB buffers being available (as we're already | |
822 // dealing with them) | |
823 bool _draining_satb_buffers; | |
824 | |
825 // number sequence of past step times | |
826 NumberSeq _step_times_ms; | |
827 // elapsed time of this task | |
828 double _elapsed_time_ms; | |
829 // termination time of this task | |
830 double _termination_time_ms; | |
831 // when this task got into the termination protocol | |
832 double _termination_start_time_ms; | |
833 | |
834 // true when the task is during a concurrent phase, false when it is | |
835 // in the remark phase (so, in the latter case, we do not have to | |
836 // check all the things that we have to check during the concurrent | |
837 // phase, i.e. SATB buffer availability...) | |
838 bool _concurrent; | |
839 | |
840 TruncatedSeq _marking_step_diffs_ms; | |
841 | |
842 // LOTS of statistics related with this task | |
843 #if _MARKING_STATS_ | |
844 NumberSeq _all_clock_intervals_ms; | |
845 double _interval_start_time_ms; | |
846 | |
847 int _aborted; | |
848 int _aborted_overflow; | |
849 int _aborted_cm_aborted; | |
850 int _aborted_yield; | |
851 int _aborted_timed_out; | |
852 int _aborted_satb; | |
853 int _aborted_termination; | |
854 | |
855 int _steal_attempts; | |
856 int _steals; | |
857 | |
858 int _clock_due_to_marking; | |
859 int _clock_due_to_scanning; | |
860 | |
861 int _local_pushes; | |
862 int _local_pops; | |
863 int _local_max_size; | |
864 int _objs_scanned; | |
865 | |
866 int _global_pushes; | |
867 int _global_pops; | |
868 int _global_max_size; | |
869 | |
870 int _global_transfers_to; | |
871 int _global_transfers_from; | |
872 | |
873 int _region_stack_pops; | |
874 | |
875 int _regions_claimed; | |
876 int _objs_found_on_bitmap; | |
877 | |
878 int _satb_buffers_processed; | |
879 #endif // _MARKING_STATS_ | |
880 | |
881 // it updates the local fields after this task has claimed | |
882 // a new region to scan | |
883 void setup_for_region(HeapRegion* hr); | |
884 // it brings up-to-date the limit of the region | |
885 void update_region_limit(); | |
886 // it resets the local fields after a task has finished scanning a | |
887 // region | |
888 void giveup_current_region(); | |
889 | |
890 // called when either the words scanned or the refs visited limit | |
891 // has been reached | |
892 void reached_limit(); | |
893 // recalculates the words scanned and refs visited limits | |
894 void recalculate_limits(); | |
895 // decreases the words scanned and refs visited limits when we reach | |
896 // an expensive operation | |
897 void decrease_limits(); | |
898 // it checks whether the words scanned or refs visited reached their | |
899 // respective limit and calls reached_limit() if they have | |
900 void check_limits() { | |
901 if (_words_scanned >= _words_scanned_limit || | |
902 _refs_reached >= _refs_reached_limit) | |
903 reached_limit(); | |
904 } | |
905 // this is supposed to be called regularly during a marking step as | |
906 // it checks a bunch of conditions that might cause the marking step | |
907 // to abort | |
908 void regular_clock_call(); | |
909 bool concurrent() { return _concurrent; } | |
910 | |
911 public: | |
912 // It resets the task; it should be called right at the beginning of | |
913 // a marking phase. | |
914 void reset(CMBitMap* _nextMarkBitMap); | |
915 // it clears all the fields that correspond to a claimed region. | |
916 void clear_region_fields(); | |
917 | |
918 void set_concurrent(bool concurrent) { _concurrent = concurrent; } | |
919 | |
920 // The main method of this class which performs a marking step | |
921 // trying not to exceed the given duration. However, it might exit | |
922 // prematurely, according to some conditions (i.e. SATB buffers are | |
923 // available for processing). | |
924 void do_marking_step(double target_ms); | |
925 | |
926 // These two calls start and stop the timer | |
927 void record_start_time() { | |
928 _elapsed_time_ms = os::elapsedTime() * 1000.0; | |
929 } | |
930 void record_end_time() { | |
931 _elapsed_time_ms = os::elapsedTime() * 1000.0 - _elapsed_time_ms; | |
932 } | |
933 | |
934 // returns the task ID | |
935 int task_id() { return _task_id; } | |
936 | |
937 // From TerminatorTerminator. It determines whether this task should | |
938 // exit the termination protocol after it's entered it. | |
939 virtual bool should_exit_termination(); | |
940 | |
941 HeapWord* finger() { return _finger; } | |
942 | |
943 bool has_aborted() { return _has_aborted; } | |
944 void set_has_aborted() { _has_aborted = true; } | |
945 void clear_has_aborted() { _has_aborted = false; } | |
946 bool claimed() { return _claimed; } | |
947 | |
948 void set_oop_closure(OopClosure* oop_closure) { | |
949 _oop_closure = oop_closure; | |
950 } | |
951 | |
952 // It grays the object by marking it and, if necessary, pushing it | |
953 // on the local queue | |
954 void deal_with_reference(oop obj); | |
955 | |
956 // It scans an object and visits its children. | |
957 void scan_object(oop obj) { | |
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958 assert(_nextMarkBitMap->isMarked((HeapWord*) obj), "invariant"); |
342 | 959 |
960 if (_cm->verbose_high()) | |
961 gclog_or_tty->print_cr("[%d] we're scanning object "PTR_FORMAT, | |
962 _task_id, (void*) obj); | |
963 | |
964 size_t obj_size = obj->size(); | |
965 _words_scanned += obj_size; | |
966 | |
967 obj->oop_iterate(_oop_closure); | |
968 statsOnly( ++_objs_scanned ); | |
969 check_limits(); | |
970 } | |
971 | |
972 // It pushes an object on the local queue. | |
973 void push(oop obj); | |
974 | |
975 // These two move entries to/from the global stack. | |
976 void move_entries_to_global_stack(); | |
977 void get_entries_from_global_stack(); | |
978 | |
979 // It pops and scans objects from the local queue. If partially is | |
980 // true, then it stops when the queue size is of a given limit. If | |
981 // partially is false, then it stops when the queue is empty. | |
982 void drain_local_queue(bool partially); | |
983 // It moves entries from the global stack to the local queue and | |
984 // drains the local queue. If partially is true, then it stops when | |
985 // both the global stack and the local queue reach a given size. If | |
986 // partially if false, it tries to empty them totally. | |
987 void drain_global_stack(bool partially); | |
988 // It keeps picking SATB buffers and processing them until no SATB | |
989 // buffers are available. | |
990 void drain_satb_buffers(); | |
991 // It keeps popping regions from the region stack and processing | |
992 // them until the region stack is empty. | |
993 void drain_region_stack(BitMapClosure* closure); | |
994 | |
995 // moves the local finger to a new location | |
996 inline void move_finger_to(HeapWord* new_finger) { | |
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997 assert(new_finger >= _finger && new_finger < _region_limit, "invariant"); |
342 | 998 _finger = new_finger; |
999 } | |
1000 | |
1001 // moves the region finger to a new location | |
1002 inline void move_region_finger_to(HeapWord* new_finger) { | |
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1003 assert(new_finger < _cm->finger(), "invariant"); |
342 | 1004 _region_finger = new_finger; |
1005 } | |
1006 | |
1007 CMTask(int task_num, ConcurrentMark *cm, | |
1008 CMTaskQueue* task_queue, CMTaskQueueSet* task_queues); | |
1009 | |
1010 // it prints statistics associated with this task | |
1011 void print_stats(); | |
1012 | |
1013 #if _MARKING_STATS_ | |
1014 void increase_objs_found_on_bitmap() { ++_objs_found_on_bitmap; } | |
1015 #endif // _MARKING_STATS_ | |
1016 }; |