Mercurial > hg > graal-jvmci-8
annotate src/share/vm/gc_implementation/g1/concurrentMark.hpp @ 1836:894b1d7c7e01
6423256: GC stacks should use a better data structure
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Reviewed-by: apetrusenko, ysr, pbk
author | jcoomes |
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date | Tue, 28 Sep 2010 15:56:15 -0700 |
parents | 4805b9f4779e |
children | f95d63e2154a |
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342 | 1 /* |
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2 * Copyright (c) 2001, 2010, Oracle and/or its affiliates. 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 * | |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
342 | 22 * |
23 */ | |
24 | |
25 class G1CollectedHeap; | |
26 class CMTask; | |
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27 typedef GenericTaskQueue<oop> CMTaskQueue; |
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28 typedef GenericTaskQueueSet<CMTaskQueue> CMTaskQueueSet; |
342 | 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). | |
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253 void push_lock_free(MemRegion mr); |
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254 |
342 | 255 // Lock-free; assumes that it will only be called in parallel |
256 // with other "pop" operations (no pushes). | |
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257 MemRegion pop_lock_free(); |
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258 |
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259 #if 0 |
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260 // The routines that manipulate the region stack with a lock are |
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261 // not currently used. They should be retained, however, as a |
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262 // diagnostic aid. |
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263 |
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264 // These two are the implementations that use a lock. They can be |
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265 // called concurrently with each other but they should not be called |
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266 // concurrently with the lock-free versions (push() / pop()). |
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267 void push_with_lock(MemRegion mr); |
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268 MemRegion pop_with_lock(); |
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269 #endif |
342 | 270 |
271 bool isEmpty() { return _index == 0; } | |
272 bool isFull() { return _index == _capacity; } | |
273 | |
274 bool overflow() { return _overflow; } | |
275 void clear_overflow() { _overflow = false; } | |
276 | |
277 int size() { return _index; } | |
278 | |
279 // It iterates over the entries in the region stack and it | |
280 // invalidates (i.e. assigns MemRegion()) the ones that point to | |
281 // regions in the collection set. | |
282 bool invalidate_entries_into_cset(); | |
283 | |
284 // This gives an upper bound up to which the iteration in | |
285 // invalidate_entries_into_cset() will reach. This prevents | |
286 // newly-added entries to be unnecessarily scanned. | |
287 void set_oops_do_bound() { | |
288 _oops_do_bound = _index; | |
289 } | |
290 | |
291 void setEmpty() { _index = 0; clear_overflow(); } | |
292 }; | |
293 | |
294 // this will enable a variety of different statistics per GC task | |
295 #define _MARKING_STATS_ 0 | |
296 // this will enable the higher verbose levels | |
297 #define _MARKING_VERBOSE_ 0 | |
298 | |
299 #if _MARKING_STATS_ | |
300 #define statsOnly(statement) \ | |
301 do { \ | |
302 statement ; \ | |
303 } while (0) | |
304 #else // _MARKING_STATS_ | |
305 #define statsOnly(statement) \ | |
306 do { \ | |
307 } while (0) | |
308 #endif // _MARKING_STATS_ | |
309 | |
310 typedef enum { | |
311 no_verbose = 0, // verbose turned off | |
312 stats_verbose, // only prints stats at the end of marking | |
313 low_verbose, // low verbose, mostly per region and per major event | |
314 medium_verbose, // a bit more detailed than low | |
315 high_verbose // per object verbose | |
316 } CMVerboseLevel; | |
317 | |
318 | |
319 class ConcurrentMarkThread; | |
320 | |
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321 class ConcurrentMark: public CHeapObj { |
342 | 322 friend class ConcurrentMarkThread; |
323 friend class CMTask; | |
324 friend class CMBitMapClosure; | |
325 friend class CSMarkOopClosure; | |
326 friend class CMGlobalObjectClosure; | |
327 friend class CMRemarkTask; | |
328 friend class CMConcurrentMarkingTask; | |
329 friend class G1ParNoteEndTask; | |
330 friend class CalcLiveObjectsClosure; | |
331 | |
332 protected: | |
333 ConcurrentMarkThread* _cmThread; // the thread doing the work | |
334 G1CollectedHeap* _g1h; // the heap. | |
335 size_t _parallel_marking_threads; // the number of marking | |
336 // threads we'll use | |
337 double _sleep_factor; // how much we have to sleep, with | |
338 // respect to the work we just did, to | |
339 // meet the marking overhead goal | |
340 double _marking_task_overhead; // marking target overhead for | |
341 // a single task | |
342 | |
343 // same as the two above, but for the cleanup task | |
344 double _cleanup_sleep_factor; | |
345 double _cleanup_task_overhead; | |
346 | |
347 // Stuff related to age cohort processing. | |
348 struct ParCleanupThreadState { | |
349 char _pre[64]; | |
350 UncleanRegionList list; | |
351 char _post[64]; | |
352 }; | |
353 ParCleanupThreadState** _par_cleanup_thread_state; | |
354 | |
355 // CMS marking support structures | |
356 CMBitMap _markBitMap1; | |
357 CMBitMap _markBitMap2; | |
358 CMBitMapRO* _prevMarkBitMap; // completed mark bitmap | |
359 CMBitMap* _nextMarkBitMap; // under-construction mark bitmap | |
360 bool _at_least_one_mark_complete; | |
361 | |
362 BitMap _region_bm; | |
363 BitMap _card_bm; | |
364 | |
365 // Heap bounds | |
366 HeapWord* _heap_start; | |
367 HeapWord* _heap_end; | |
368 | |
369 // For gray objects | |
370 CMMarkStack _markStack; // Grey objects behind global finger. | |
371 CMRegionStack _regionStack; // Grey regions behind global finger. | |
372 HeapWord* volatile _finger; // the global finger, region aligned, | |
373 // always points to the end of the | |
374 // last claimed region | |
375 | |
376 // marking tasks | |
377 size_t _max_task_num; // maximum task number | |
378 size_t _active_tasks; // task num currently active | |
379 CMTask** _tasks; // task queue array (max_task_num len) | |
380 CMTaskQueueSet* _task_queues; // task queue set | |
381 ParallelTaskTerminator _terminator; // for termination | |
382 | |
383 // Two sync barriers that are used to synchronise tasks when an | |
384 // overflow occurs. The algorithm is the following. All tasks enter | |
385 // the first one to ensure that they have all stopped manipulating | |
386 // the global data structures. After they exit it, they re-initialise | |
387 // their data structures and task 0 re-initialises the global data | |
388 // structures. Then, they enter the second sync barrier. This | |
389 // ensure, that no task starts doing work before all data | |
390 // structures (local and global) have been re-initialised. When they | |
391 // exit it, they are free to start working again. | |
392 WorkGangBarrierSync _first_overflow_barrier_sync; | |
393 WorkGangBarrierSync _second_overflow_barrier_sync; | |
394 | |
395 | |
396 // this is set by any task, when an overflow on the global data | |
397 // structures is detected. | |
398 volatile bool _has_overflown; | |
399 // true: marking is concurrent, false: we're in remark | |
400 volatile bool _concurrent; | |
401 // set at the end of a Full GC so that marking aborts | |
402 volatile bool _has_aborted; | |
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403 |
342 | 404 // used when remark aborts due to an overflow to indicate that |
405 // another concurrent marking phase should start | |
406 volatile bool _restart_for_overflow; | |
407 | |
408 // This is true from the very start of concurrent marking until the | |
409 // point when all the tasks complete their work. It is really used | |
410 // to determine the points between the end of concurrent marking and | |
411 // time of remark. | |
412 volatile bool _concurrent_marking_in_progress; | |
413 | |
414 // verbose level | |
415 CMVerboseLevel _verbose_level; | |
416 | |
417 // These two fields are used to implement the optimisation that | |
418 // avoids pushing objects on the global/region stack if there are | |
419 // no collection set regions above the lowest finger. | |
420 | |
421 // This is the lowest finger (among the global and local fingers), | |
422 // which is calculated before a new collection set is chosen. | |
423 HeapWord* _min_finger; | |
424 // If this flag is true, objects/regions that are marked below the | |
425 // finger should be pushed on the stack(s). If this is flag is | |
426 // false, it is safe not to push them on the stack(s). | |
427 bool _should_gray_objects; | |
428 | |
429 // All of these times are in ms. | |
430 NumberSeq _init_times; | |
431 NumberSeq _remark_times; | |
432 NumberSeq _remark_mark_times; | |
433 NumberSeq _remark_weak_ref_times; | |
434 NumberSeq _cleanup_times; | |
435 double _total_counting_time; | |
436 double _total_rs_scrub_time; | |
437 | |
438 double* _accum_task_vtime; // accumulated task vtime | |
439 | |
440 WorkGang* _parallel_workers; | |
441 | |
442 void weakRefsWork(bool clear_all_soft_refs); | |
443 | |
444 void swapMarkBitMaps(); | |
445 | |
446 // It resets the global marking data structures, as well as the | |
447 // task local ones; should be called during initial mark. | |
448 void reset(); | |
449 // It resets all the marking data structures. | |
450 void clear_marking_state(); | |
451 | |
452 // It should be called to indicate which phase we're in (concurrent | |
453 // mark or remark) and how many threads are currently active. | |
454 void set_phase(size_t active_tasks, bool concurrent); | |
455 // We do this after we're done with marking so that the marking data | |
456 // structures are initialised to a sensible and predictable state. | |
457 void set_non_marking_state(); | |
458 | |
459 // prints all gathered CM-related statistics | |
460 void print_stats(); | |
461 | |
462 // accessor methods | |
463 size_t parallel_marking_threads() { return _parallel_marking_threads; } | |
464 double sleep_factor() { return _sleep_factor; } | |
465 double marking_task_overhead() { return _marking_task_overhead;} | |
466 double cleanup_sleep_factor() { return _cleanup_sleep_factor; } | |
467 double cleanup_task_overhead() { return _cleanup_task_overhead;} | |
468 | |
469 HeapWord* finger() { return _finger; } | |
470 bool concurrent() { return _concurrent; } | |
471 size_t active_tasks() { return _active_tasks; } | |
472 ParallelTaskTerminator* terminator() { return &_terminator; } | |
473 | |
474 // It claims the next available region to be scanned by a marking | |
475 // task. It might return NULL if the next region is empty or we have | |
476 // run out of regions. In the latter case, out_of_regions() | |
477 // determines whether we've really run out of regions or the task | |
478 // should call claim_region() again. This might seem a bit | |
479 // awkward. Originally, the code was written so that claim_region() | |
480 // either successfully returned with a non-empty region or there | |
481 // were no more regions to be claimed. The problem with this was | |
482 // that, in certain circumstances, it iterated over large chunks of | |
483 // the heap finding only empty regions and, while it was working, it | |
484 // was preventing the calling task to call its regular clock | |
485 // method. So, this way, each task will spend very little time in | |
486 // claim_region() and is allowed to call the regular clock method | |
487 // frequently. | |
488 HeapRegion* claim_region(int task); | |
489 | |
490 // It determines whether we've run out of regions to scan. | |
491 bool out_of_regions() { return _finger == _heap_end; } | |
492 | |
493 // Returns the task with the given id | |
494 CMTask* task(int id) { | |
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495 assert(0 <= id && id < (int) _active_tasks, |
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496 "task id not within active bounds"); |
342 | 497 return _tasks[id]; |
498 } | |
499 | |
500 // Returns the task queue with the given id | |
501 CMTaskQueue* task_queue(int id) { | |
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502 assert(0 <= id && id < (int) _active_tasks, |
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503 "task queue id not within active bounds"); |
342 | 504 return (CMTaskQueue*) _task_queues->queue(id); |
505 } | |
506 | |
507 // Returns the task queue set | |
508 CMTaskQueueSet* task_queues() { return _task_queues; } | |
509 | |
510 // Access / manipulation of the overflow flag which is set to | |
511 // indicate that the global stack or region stack has overflown | |
512 bool has_overflown() { return _has_overflown; } | |
513 void set_has_overflown() { _has_overflown = true; } | |
514 void clear_has_overflown() { _has_overflown = false; } | |
515 | |
516 bool has_aborted() { return _has_aborted; } | |
517 bool restart_for_overflow() { return _restart_for_overflow; } | |
518 | |
519 // Methods to enter the two overflow sync barriers | |
520 void enter_first_sync_barrier(int task_num); | |
521 void enter_second_sync_barrier(int task_num); | |
522 | |
523 public: | |
524 // Manipulation of the global mark stack. | |
525 // Notice that the first mark_stack_push is CAS-based, whereas the | |
526 // two below are Mutex-based. This is OK since the first one is only | |
527 // called during evacuation pauses and doesn't compete with the | |
528 // other two (which are called by the marking tasks during | |
529 // concurrent marking or remark). | |
530 bool mark_stack_push(oop p) { | |
531 _markStack.par_push(p); | |
532 if (_markStack.overflow()) { | |
533 set_has_overflown(); | |
534 return false; | |
535 } | |
536 return true; | |
537 } | |
538 bool mark_stack_push(oop* arr, int n) { | |
539 _markStack.par_push_arr(arr, n); | |
540 if (_markStack.overflow()) { | |
541 set_has_overflown(); | |
542 return false; | |
543 } | |
544 return true; | |
545 } | |
546 void mark_stack_pop(oop* arr, int max, int* n) { | |
547 _markStack.par_pop_arr(arr, max, n); | |
548 } | |
549 size_t mark_stack_size() { return _markStack.size(); } | |
550 size_t partial_mark_stack_size_target() { return _markStack.maxElems()/3; } | |
551 bool mark_stack_overflow() { return _markStack.overflow(); } | |
552 bool mark_stack_empty() { return _markStack.isEmpty(); } | |
553 | |
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554 // (Lock-free) Manipulation of the region stack |
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555 bool region_stack_push_lock_free(MemRegion mr) { |
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556 // Currently we only call the lock-free version during evacuation |
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557 // pauses. |
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558 assert(SafepointSynchronize::is_at_safepoint(), "world should be stopped"); |
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559 |
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560 _regionStack.push_lock_free(mr); |
342 | 561 if (_regionStack.overflow()) { |
562 set_has_overflown(); | |
563 return false; | |
564 } | |
565 return true; | |
566 } | |
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567 |
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568 // Lock-free version of region-stack pop. Should only be |
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569 // called in tandem with other lock-free pops. |
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570 MemRegion region_stack_pop_lock_free() { |
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571 return _regionStack.pop_lock_free(); |
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572 } |
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573 |
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574 #if 0 |
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575 // The routines that manipulate the region stack with a lock are |
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576 // not currently used. They should be retained, however, as a |
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577 // diagnostic aid. |
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578 |
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579 bool region_stack_push_with_lock(MemRegion mr) { |
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580 // Currently we only call the lock-based version during either |
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581 // concurrent marking or remark. |
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582 assert(!SafepointSynchronize::is_at_safepoint() || !concurrent(), |
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583 "if we are at a safepoint it should be the remark safepoint"); |
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584 |
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585 _regionStack.push_with_lock(mr); |
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586 if (_regionStack.overflow()) { |
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587 set_has_overflown(); |
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588 return false; |
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589 } |
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590 return true; |
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591 } |
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592 |
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593 MemRegion region_stack_pop_with_lock() { |
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594 // Currently we only call the lock-based version during either |
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595 // concurrent marking or remark. |
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596 assert(!SafepointSynchronize::is_at_safepoint() || !concurrent(), |
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597 "if we are at a safepoint it should be the remark safepoint"); |
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598 |
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599 return _regionStack.pop_with_lock(); |
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600 } |
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601 #endif |
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602 |
342 | 603 int region_stack_size() { return _regionStack.size(); } |
604 bool region_stack_overflow() { return _regionStack.overflow(); } | |
605 bool region_stack_empty() { return _regionStack.isEmpty(); } | |
606 | |
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607 // Iterate over any regions that were aborted while draining the |
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608 // region stack (any such regions are saved in the corresponding |
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609 // CMTask) and invalidate (i.e. assign to the empty MemRegion()) |
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610 // any regions that point into the collection set. |
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611 bool invalidate_aborted_regions_in_cset(); |
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612 |
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613 // Returns true if there are any aborted memory regions. |
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614 bool has_aborted_regions(); |
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615 |
342 | 616 bool concurrent_marking_in_progress() { |
617 return _concurrent_marking_in_progress; | |
618 } | |
619 void set_concurrent_marking_in_progress() { | |
620 _concurrent_marking_in_progress = true; | |
621 } | |
622 void clear_concurrent_marking_in_progress() { | |
623 _concurrent_marking_in_progress = false; | |
624 } | |
625 | |
626 void update_accum_task_vtime(int i, double vtime) { | |
627 _accum_task_vtime[i] += vtime; | |
628 } | |
629 | |
630 double all_task_accum_vtime() { | |
631 double ret = 0.0; | |
632 for (int i = 0; i < (int)_max_task_num; ++i) | |
633 ret += _accum_task_vtime[i]; | |
634 return ret; | |
635 } | |
636 | |
637 // Attempts to steal an object from the task queues of other tasks | |
638 bool try_stealing(int task_num, int* hash_seed, oop& obj) { | |
639 return _task_queues->steal(task_num, hash_seed, obj); | |
640 } | |
641 | |
642 // It grays an object by first marking it. Then, if it's behind the | |
643 // global finger, it also pushes it on the global stack. | |
644 void deal_with_reference(oop obj); | |
645 | |
646 ConcurrentMark(ReservedSpace rs, int max_regions); | |
647 ~ConcurrentMark(); | |
648 ConcurrentMarkThread* cmThread() { return _cmThread; } | |
649 | |
650 CMBitMapRO* prevMarkBitMap() const { return _prevMarkBitMap; } | |
651 CMBitMap* nextMarkBitMap() const { return _nextMarkBitMap; } | |
652 | |
653 // The following three are interaction between CM and | |
654 // G1CollectedHeap | |
655 | |
656 // This notifies CM that a root during initial-mark needs to be | |
657 // grayed and it's MT-safe. Currently, we just mark it. But, in the | |
658 // future, we can experiment with pushing it on the stack and we can | |
659 // do this without changing G1CollectedHeap. | |
660 void grayRoot(oop p); | |
661 // It's used during evacuation pauses to gray a region, if | |
662 // necessary, and it's MT-safe. It assumes that the caller has | |
663 // marked any objects on that region. If _should_gray_objects is | |
664 // true and we're still doing concurrent marking, the region is | |
665 // pushed on the region stack, if it is located below the global | |
666 // finger, otherwise we do nothing. | |
667 void grayRegionIfNecessary(MemRegion mr); | |
668 // It's used during evacuation pauses to mark and, if necessary, | |
669 // gray a single object and it's MT-safe. It assumes the caller did | |
670 // not mark the object. If _should_gray_objects is true and we're | |
671 // still doing concurrent marking, the objects is pushed on the | |
672 // global stack, if it is located below the global finger, otherwise | |
673 // we do nothing. | |
674 void markAndGrayObjectIfNecessary(oop p); | |
675 | |
1388 | 676 // It iterates over the heap and for each object it comes across it |
677 // will dump the contents of its reference fields, as well as | |
678 // liveness information for the object and its referents. The dump | |
679 // will be written to a file with the following name: | |
680 // G1PrintReachableBaseFile + "." + str. use_prev_marking decides | |
681 // whether the prev (use_prev_marking == true) or next | |
682 // (use_prev_marking == false) marking information will be used to | |
683 // determine the liveness of each object / referent. If all is true, | |
684 // all objects in the heap will be dumped, otherwise only the live | |
685 // ones. In the dump the following symbols / abbreviations are used: | |
686 // M : an explicitly live object (its bitmap bit is set) | |
687 // > : an implicitly live object (over tams) | |
688 // O : an object outside the G1 heap (typically: in the perm gen) | |
689 // NOT : a reference field whose referent is not live | |
690 // AND MARKED : indicates that an object is both explicitly and | |
691 // implicitly live (it should be one or the other, not both) | |
692 void print_reachable(const char* str, | |
693 bool use_prev_marking, bool all) PRODUCT_RETURN; | |
342 | 694 |
695 // Clear the next marking bitmap (will be called concurrently). | |
696 void clearNextBitmap(); | |
697 | |
698 // main CMS steps and related support | |
699 void checkpointRootsInitial(); | |
700 | |
701 // These two do the work that needs to be done before and after the | |
702 // initial root checkpoint. Since this checkpoint can be done at two | |
703 // different points (i.e. an explicit pause or piggy-backed on a | |
704 // young collection), then it's nice to be able to easily share the | |
705 // pre/post code. It might be the case that we can put everything in | |
706 // the post method. TP | |
707 void checkpointRootsInitialPre(); | |
708 void checkpointRootsInitialPost(); | |
709 | |
710 // Do concurrent phase of marking, to a tentative transitive closure. | |
711 void markFromRoots(); | |
712 | |
713 // Process all unprocessed SATB buffers. It is called at the | |
714 // beginning of an evacuation pause. | |
715 void drainAllSATBBuffers(); | |
716 | |
717 void checkpointRootsFinal(bool clear_all_soft_refs); | |
718 void checkpointRootsFinalWork(); | |
719 void calcDesiredRegions(); | |
720 void cleanup(); | |
721 void completeCleanup(); | |
722 | |
723 // Mark in the previous bitmap. NB: this is usually read-only, so use | |
724 // this carefully! | |
725 void markPrev(oop p); | |
726 void clear(oop p); | |
727 // Clears marks for all objects in the given range, for both prev and | |
728 // next bitmaps. NB: the previous bitmap is usually read-only, so use | |
729 // this carefully! | |
730 void clearRangeBothMaps(MemRegion mr); | |
731 | |
732 // Record the current top of the mark and region stacks; a | |
733 // subsequent oops_do() on the mark stack and | |
734 // invalidate_entries_into_cset() on the region stack will iterate | |
735 // only over indices valid at the time of this call. | |
736 void set_oops_do_bound() { | |
737 _markStack.set_oops_do_bound(); | |
738 _regionStack.set_oops_do_bound(); | |
739 } | |
740 // Iterate over the oops in the mark stack and all local queues. It | |
741 // also calls invalidate_entries_into_cset() on the region stack. | |
742 void oops_do(OopClosure* f); | |
743 // It is called at the end of an evacuation pause during marking so | |
744 // that CM is notified of where the new end of the heap is. It | |
745 // doesn't do anything if concurrent_marking_in_progress() is false, | |
746 // unless the force parameter is true. | |
747 void update_g1_committed(bool force = false); | |
748 | |
749 void complete_marking_in_collection_set(); | |
750 | |
751 // It indicates that a new collection set is being chosen. | |
752 void newCSet(); | |
753 // It registers a collection set heap region with CM. This is used | |
754 // to determine whether any heap regions are located above the finger. | |
755 void registerCSetRegion(HeapRegion* hr); | |
756 | |
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757 // Registers the maximum region-end associated with a set of |
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758 // regions with CM. Again this is used to determine whether any |
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759 // heap regions are located above the finger. |
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760 void register_collection_set_finger(HeapWord* max_finger) { |
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761 // max_finger is the highest heap region end of the regions currently |
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762 // contained in the collection set. If this value is larger than |
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763 // _min_finger then we need to gray objects. |
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764 // This routine is like registerCSetRegion but for an entire |
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765 // collection of regions. |
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766 if (max_finger > _min_finger) |
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767 _should_gray_objects = true; |
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768 } |
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769 |
342 | 770 // Returns "true" if at least one mark has been completed. |
771 bool at_least_one_mark_complete() { return _at_least_one_mark_complete; } | |
772 | |
773 bool isMarked(oop p) const { | |
774 assert(p != NULL && p->is_oop(), "expected an oop"); | |
775 HeapWord* addr = (HeapWord*)p; | |
776 assert(addr >= _nextMarkBitMap->startWord() || | |
777 addr < _nextMarkBitMap->endWord(), "in a region"); | |
778 | |
779 return _nextMarkBitMap->isMarked(addr); | |
780 } | |
781 | |
782 inline bool not_yet_marked(oop p) const; | |
783 | |
784 // XXX Debug code | |
785 bool containing_card_is_marked(void* p); | |
786 bool containing_cards_are_marked(void* start, void* last); | |
787 | |
788 bool isPrevMarked(oop p) const { | |
789 assert(p != NULL && p->is_oop(), "expected an oop"); | |
790 HeapWord* addr = (HeapWord*)p; | |
791 assert(addr >= _prevMarkBitMap->startWord() || | |
792 addr < _prevMarkBitMap->endWord(), "in a region"); | |
793 | |
794 return _prevMarkBitMap->isMarked(addr); | |
795 } | |
796 | |
797 inline bool do_yield_check(int worker_i = 0); | |
798 inline bool should_yield(); | |
799 | |
800 // Called to abort the marking cycle after a Full GC takes palce. | |
801 void abort(); | |
802 | |
803 // This prints the global/local fingers. It is used for debugging. | |
804 NOT_PRODUCT(void print_finger();) | |
805 | |
806 void print_summary_info(); | |
807 | |
1019 | 808 void print_worker_threads_on(outputStream* st) const; |
809 | |
342 | 810 // The following indicate whether a given verbose level has been |
811 // set. Notice that anything above stats is conditional to | |
812 // _MARKING_VERBOSE_ having been set to 1 | |
813 bool verbose_stats() | |
814 { return _verbose_level >= stats_verbose; } | |
815 bool verbose_low() | |
816 { return _MARKING_VERBOSE_ && _verbose_level >= low_verbose; } | |
817 bool verbose_medium() | |
818 { return _MARKING_VERBOSE_ && _verbose_level >= medium_verbose; } | |
819 bool verbose_high() | |
820 { return _MARKING_VERBOSE_ && _verbose_level >= high_verbose; } | |
821 }; | |
822 | |
823 // A class representing a marking task. | |
824 class CMTask : public TerminatorTerminator { | |
825 private: | |
826 enum PrivateConstants { | |
827 // the regular clock call is called once the scanned words reaches | |
828 // this limit | |
829 words_scanned_period = 12*1024, | |
830 // the regular clock call is called once the number of visited | |
831 // references reaches this limit | |
832 refs_reached_period = 384, | |
833 // initial value for the hash seed, used in the work stealing code | |
834 init_hash_seed = 17, | |
835 // how many entries will be transferred between global stack and | |
836 // local queues | |
837 global_stack_transfer_size = 16 | |
838 }; | |
839 | |
840 int _task_id; | |
841 G1CollectedHeap* _g1h; | |
842 ConcurrentMark* _cm; | |
843 CMBitMap* _nextMarkBitMap; | |
844 // the task queue of this task | |
845 CMTaskQueue* _task_queue; | |
845
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846 private: |
342 | 847 // the task queue set---needed for stealing |
848 CMTaskQueueSet* _task_queues; | |
849 // indicates whether the task has been claimed---this is only for | |
850 // debugging purposes | |
851 bool _claimed; | |
852 | |
853 // number of calls to this task | |
854 int _calls; | |
855 | |
856 // when the virtual timer reaches this time, the marking step should | |
857 // exit | |
858 double _time_target_ms; | |
859 // the start time of the current marking step | |
860 double _start_time_ms; | |
861 | |
862 // the oop closure used for iterations over oops | |
863 OopClosure* _oop_closure; | |
864 | |
865 // the region this task is scanning, NULL if we're not scanning any | |
866 HeapRegion* _curr_region; | |
867 // the local finger of this task, NULL if we're not scanning a region | |
868 HeapWord* _finger; | |
869 // limit of the region this task is scanning, NULL if we're not scanning one | |
870 HeapWord* _region_limit; | |
871 | |
872 // This is used only when we scan regions popped from the region | |
873 // stack. It records what the last object on such a region we | |
874 // scanned was. It is used to ensure that, if we abort region | |
875 // iteration, we do not rescan the first part of the region. This | |
876 // should be NULL when we're not scanning a region from the region | |
877 // stack. | |
878 HeapWord* _region_finger; | |
879 | |
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880 // If we abort while scanning a region we record the remaining |
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881 // unscanned portion and check this field when marking restarts. |
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882 // This avoids having to push on the region stack while other |
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883 // marking threads may still be popping regions. |
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884 // If we were to push the unscanned portion directly to the |
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885 // region stack then we would need to using locking versions |
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886 // of the push and pop operations. |
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887 MemRegion _aborted_region; |
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888 |
342 | 889 // the number of words this task has scanned |
890 size_t _words_scanned; | |
891 // When _words_scanned reaches this limit, the regular clock is | |
892 // called. Notice that this might be decreased under certain | |
893 // circumstances (i.e. when we believe that we did an expensive | |
894 // operation). | |
895 size_t _words_scanned_limit; | |
896 // the initial value of _words_scanned_limit (i.e. what it was | |
897 // before it was decreased). | |
898 size_t _real_words_scanned_limit; | |
899 | |
900 // the number of references this task has visited | |
901 size_t _refs_reached; | |
902 // When _refs_reached reaches this limit, the regular clock is | |
903 // called. Notice this this might be decreased under certain | |
904 // circumstances (i.e. when we believe that we did an expensive | |
905 // operation). | |
906 size_t _refs_reached_limit; | |
907 // the initial value of _refs_reached_limit (i.e. what it was before | |
908 // it was decreased). | |
909 size_t _real_refs_reached_limit; | |
910 | |
911 // used by the work stealing stuff | |
912 int _hash_seed; | |
913 // if this is true, then the task has aborted for some reason | |
914 bool _has_aborted; | |
915 // set when the task aborts because it has met its time quota | |
916 bool _has_aborted_timed_out; | |
917 // true when we're draining SATB buffers; this avoids the task | |
918 // aborting due to SATB buffers being available (as we're already | |
919 // dealing with them) | |
920 bool _draining_satb_buffers; | |
921 | |
922 // number sequence of past step times | |
923 NumberSeq _step_times_ms; | |
924 // elapsed time of this task | |
925 double _elapsed_time_ms; | |
926 // termination time of this task | |
927 double _termination_time_ms; | |
928 // when this task got into the termination protocol | |
929 double _termination_start_time_ms; | |
930 | |
931 // true when the task is during a concurrent phase, false when it is | |
932 // in the remark phase (so, in the latter case, we do not have to | |
933 // check all the things that we have to check during the concurrent | |
934 // phase, i.e. SATB buffer availability...) | |
935 bool _concurrent; | |
936 | |
937 TruncatedSeq _marking_step_diffs_ms; | |
938 | |
939 // LOTS of statistics related with this task | |
940 #if _MARKING_STATS_ | |
941 NumberSeq _all_clock_intervals_ms; | |
942 double _interval_start_time_ms; | |
943 | |
944 int _aborted; | |
945 int _aborted_overflow; | |
946 int _aborted_cm_aborted; | |
947 int _aborted_yield; | |
948 int _aborted_timed_out; | |
949 int _aborted_satb; | |
950 int _aborted_termination; | |
951 | |
952 int _steal_attempts; | |
953 int _steals; | |
954 | |
955 int _clock_due_to_marking; | |
956 int _clock_due_to_scanning; | |
957 | |
958 int _local_pushes; | |
959 int _local_pops; | |
960 int _local_max_size; | |
961 int _objs_scanned; | |
962 | |
963 int _global_pushes; | |
964 int _global_pops; | |
965 int _global_max_size; | |
966 | |
967 int _global_transfers_to; | |
968 int _global_transfers_from; | |
969 | |
970 int _region_stack_pops; | |
971 | |
972 int _regions_claimed; | |
973 int _objs_found_on_bitmap; | |
974 | |
975 int _satb_buffers_processed; | |
976 #endif // _MARKING_STATS_ | |
977 | |
978 // it updates the local fields after this task has claimed | |
979 // a new region to scan | |
980 void setup_for_region(HeapRegion* hr); | |
981 // it brings up-to-date the limit of the region | |
982 void update_region_limit(); | |
983 // it resets the local fields after a task has finished scanning a | |
984 // region | |
985 void giveup_current_region(); | |
986 | |
987 // called when either the words scanned or the refs visited limit | |
988 // has been reached | |
989 void reached_limit(); | |
990 // recalculates the words scanned and refs visited limits | |
991 void recalculate_limits(); | |
992 // decreases the words scanned and refs visited limits when we reach | |
993 // an expensive operation | |
994 void decrease_limits(); | |
995 // it checks whether the words scanned or refs visited reached their | |
996 // respective limit and calls reached_limit() if they have | |
997 void check_limits() { | |
998 if (_words_scanned >= _words_scanned_limit || | |
999 _refs_reached >= _refs_reached_limit) | |
1000 reached_limit(); | |
1001 } | |
1002 // this is supposed to be called regularly during a marking step as | |
1003 // it checks a bunch of conditions that might cause the marking step | |
1004 // to abort | |
1005 void regular_clock_call(); | |
1006 bool concurrent() { return _concurrent; } | |
1007 | |
1008 public: | |
1009 // It resets the task; it should be called right at the beginning of | |
1010 // a marking phase. | |
1011 void reset(CMBitMap* _nextMarkBitMap); | |
1012 // it clears all the fields that correspond to a claimed region. | |
1013 void clear_region_fields(); | |
1014 | |
1015 void set_concurrent(bool concurrent) { _concurrent = concurrent; } | |
1016 | |
1017 // The main method of this class which performs a marking step | |
1018 // trying not to exceed the given duration. However, it might exit | |
1019 // prematurely, according to some conditions (i.e. SATB buffers are | |
1020 // available for processing). | |
1021 void do_marking_step(double target_ms); | |
1022 | |
1023 // These two calls start and stop the timer | |
1024 void record_start_time() { | |
1025 _elapsed_time_ms = os::elapsedTime() * 1000.0; | |
1026 } | |
1027 void record_end_time() { | |
1028 _elapsed_time_ms = os::elapsedTime() * 1000.0 - _elapsed_time_ms; | |
1029 } | |
1030 | |
1031 // returns the task ID | |
1032 int task_id() { return _task_id; } | |
1033 | |
1034 // From TerminatorTerminator. It determines whether this task should | |
1035 // exit the termination protocol after it's entered it. | |
1036 virtual bool should_exit_termination(); | |
1037 | |
1038 HeapWord* finger() { return _finger; } | |
1039 | |
1040 bool has_aborted() { return _has_aborted; } | |
1041 void set_has_aborted() { _has_aborted = true; } | |
1042 void clear_has_aborted() { _has_aborted = false; } | |
1043 bool claimed() { return _claimed; } | |
1044 | |
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1045 // Support routines for the partially scanned region that may be |
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1046 // recorded as a result of aborting while draining the CMRegionStack |
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1047 MemRegion aborted_region() { return _aborted_region; } |
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1048 void set_aborted_region(MemRegion mr) |
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1049 { _aborted_region = mr; } |
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1050 |
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1051 // Clears any recorded partially scanned region |
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1052 void clear_aborted_region() { set_aborted_region(MemRegion()); } |
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1053 |
342 | 1054 void set_oop_closure(OopClosure* oop_closure) { |
1055 _oop_closure = oop_closure; | |
1056 } | |
1057 | |
1058 // It grays the object by marking it and, if necessary, pushing it | |
1059 // on the local queue | |
1060 void deal_with_reference(oop obj); | |
1061 | |
1062 // It scans an object and visits its children. | |
1063 void scan_object(oop obj) { | |
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1064 assert(_nextMarkBitMap->isMarked((HeapWord*) obj), "invariant"); |
342 | 1065 |
1066 if (_cm->verbose_high()) | |
1067 gclog_or_tty->print_cr("[%d] we're scanning object "PTR_FORMAT, | |
1068 _task_id, (void*) obj); | |
1069 | |
1070 size_t obj_size = obj->size(); | |
1071 _words_scanned += obj_size; | |
1072 | |
1073 obj->oop_iterate(_oop_closure); | |
1074 statsOnly( ++_objs_scanned ); | |
1075 check_limits(); | |
1076 } | |
1077 | |
1078 // It pushes an object on the local queue. | |
1079 void push(oop obj); | |
1080 | |
1081 // These two move entries to/from the global stack. | |
1082 void move_entries_to_global_stack(); | |
1083 void get_entries_from_global_stack(); | |
1084 | |
1085 // It pops and scans objects from the local queue. If partially is | |
1086 // true, then it stops when the queue size is of a given limit. If | |
1087 // partially is false, then it stops when the queue is empty. | |
1088 void drain_local_queue(bool partially); | |
1089 // It moves entries from the global stack to the local queue and | |
1090 // drains the local queue. If partially is true, then it stops when | |
1091 // both the global stack and the local queue reach a given size. If | |
1092 // partially if false, it tries to empty them totally. | |
1093 void drain_global_stack(bool partially); | |
1094 // It keeps picking SATB buffers and processing them until no SATB | |
1095 // buffers are available. | |
1096 void drain_satb_buffers(); | |
1097 // It keeps popping regions from the region stack and processing | |
1098 // them until the region stack is empty. | |
1099 void drain_region_stack(BitMapClosure* closure); | |
1100 | |
1101 // moves the local finger to a new location | |
1102 inline void move_finger_to(HeapWord* new_finger) { | |
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1103 assert(new_finger >= _finger && new_finger < _region_limit, "invariant"); |
342 | 1104 _finger = new_finger; |
1105 } | |
1106 | |
1107 // moves the region finger to a new location | |
1108 inline void move_region_finger_to(HeapWord* new_finger) { | |
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1109 assert(new_finger < _cm->finger(), "invariant"); |
342 | 1110 _region_finger = new_finger; |
1111 } | |
1112 | |
1113 CMTask(int task_num, ConcurrentMark *cm, | |
1114 CMTaskQueue* task_queue, CMTaskQueueSet* task_queues); | |
1115 | |
1116 // it prints statistics associated with this task | |
1117 void print_stats(); | |
1118 | |
1119 #if _MARKING_STATS_ | |
1120 void increase_objs_found_on_bitmap() { ++_objs_found_on_bitmap; } | |
1121 #endif // _MARKING_STATS_ | |
1122 }; |