1 /*
2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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24
25 #ifndef SHARE_VM_GC_G1_CONCURRENTMARK_HPP
26 #define SHARE_VM_GC_G1_CONCURRENTMARK_HPP
27
28 #include "classfile/javaClasses.hpp"
29 #include "gc/g1/g1RegionToSpaceMapper.hpp"
30 #include "gc/g1/heapRegionSet.hpp"
31 #include "gc/shared/cmBitMap.inline.hpp"
32 #include "gc/shared/gcId.hpp"
33 #include "gc/shared/taskqueue.hpp"
34
35 class G1CollectedHeap;
36 class CMBitMap;
37 class CMTask;
38 class ConcurrentMark;
39 typedef GenericTaskQueue<oop, mtGC> CMTaskQueue;
40 typedef GenericTaskQueueSet<CMTaskQueue, mtGC> CMTaskQueueSet;
41
42 // Closure used by CM during concurrent reference discovery
43 // and reference processing (during remarking) to determine
44 // if a particular object is alive. It is primarily used
45 // to determine if referents of discovered reference objects
46 // are alive. An instance is also embedded into the
47 // reference processor as the _is_alive_non_header field
48 class G1CMIsAliveClosure: public BoolObjectClosure {
49 G1CollectedHeap* _g1;
50 public:
51 G1CMIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) { }
52
53 bool do_object_b(oop obj);
54 };
55
56 class CMBitMapMappingChangedListener : public G1MappingChangedListener {
57 private:
58 CMBitMap* _bm;
59 public:
60 CMBitMapMappingChangedListener() : _bm(NULL) {}
61
62 void set_bitmap(CMBitMap* bm) { _bm = bm; }
63
64 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
65 };
66
67 class G1CMBitMap : public CMBitMap {
68 private:
69 CMBitMapMappingChangedListener _listener;
70
71 public:
72 G1CMBitMap() : CMBitMap(), _listener() { _listener.set_bitmap(this); }
73 static size_t compute_size(size_t heap_size);
74 // Returns the amount of bytes on the heap between two marks in the bitmap.
75 static size_t mark_distance();
76 // Returns how many bytes (or bits) of the heap a single byte (or bit) of the
77 // mark bitmap corresponds to. This is the same as the mark distance above.
78 static size_t heap_map_factor() {
79 return mark_distance();
80 }
81
82 // Initializes the underlying BitMap to cover the given area.
83 void initialize(MemRegion heap, G1RegionToSpaceMapper* storage);
84
85 // Clear the whole mark bitmap.
86 void clearAll();
87 };
88
89 // Represents a marking stack used by ConcurrentMarking in the G1 collector.
90 class CMMarkStack VALUE_OBJ_CLASS_SPEC {
91 VirtualSpace _virtual_space; // Underlying backing store for actual stack
92 ConcurrentMark* _cm;
93 oop* _base; // bottom of stack
94 jint _index; // one more than last occupied index
95 jint _capacity; // max #elements
96 jint _saved_index; // value of _index saved at start of GC
97
98 bool _overflow;
99 bool _should_expand;
100 DEBUG_ONLY(bool _drain_in_progress;)
101 DEBUG_ONLY(bool _drain_in_progress_yields;)
102
103 oop pop() {
104 if (!isEmpty()) {
105 return _base[--_index] ;
106 }
107 return NULL;
108 }
109
110 public:
111 CMMarkStack(ConcurrentMark* cm);
112 ~CMMarkStack();
113
114 bool allocate(size_t capacity);
115
116 // Pushes the first "n" elements of "ptr_arr" on the stack.
117 // Locking impl: concurrency is allowed only with
118 // "par_push_arr" and/or "par_pop_arr" operations, which use the same
119 // locking strategy.
120 void par_push_arr(oop* ptr_arr, int n);
121
122 // If returns false, the array was empty. Otherwise, removes up to "max"
123 // elements from the stack, and transfers them to "ptr_arr" in an
124 // unspecified order. The actual number transferred is given in "n" ("n
125 // == 0" is deliberately redundant with the return value.) Locking impl:
126 // concurrency is allowed only with "par_push_arr" and/or "par_pop_arr"
127 // operations, which use the same locking strategy.
128 bool par_pop_arr(oop* ptr_arr, int max, int* n);
129
130 // Drain the mark stack, applying the given closure to all fields of
131 // objects on the stack. (That is, continue until the stack is empty,
132 // even if closure applications add entries to the stack.) The "bm"
133 // argument, if non-null, may be used to verify that only marked objects
134 // are on the mark stack. If "yield_after" is "true", then the
135 // concurrent marker performing the drain offers to yield after
136 // processing each object. If a yield occurs, stops the drain operation
137 // and returns false. Otherwise, returns true.
138 template<class OopClosureClass>
139 bool drain(OopClosureClass* cl, CMBitMap* bm, bool yield_after = false);
140
141 bool isEmpty() { return _index == 0; }
142 int maxElems() { return _capacity; }
143
144 bool overflow() { return _overflow; }
145 void clear_overflow() { _overflow = false; }
146
147 bool should_expand() const { return _should_expand; }
148 void set_should_expand();
149
150 // Expand the stack, typically in response to an overflow condition
151 void expand();
152
153 int size() { return _index; }
154
155 void setEmpty() { _index = 0; clear_overflow(); }
156
157 // Record the current index.
158 void note_start_of_gc();
159
160 // Make sure that we have not added any entries to the stack during GC.
161 void note_end_of_gc();
162
163 // Apply fn to each oop in the mark stack, up to the bound recorded
164 // via one of the above "note" functions. The mark stack must not
165 // be modified while iterating.
166 template<typename Fn> void iterate(Fn fn);
167 };
168
169 class ForceOverflowSettings VALUE_OBJ_CLASS_SPEC {
170 private:
171 #ifndef PRODUCT
172 uintx _num_remaining;
173 bool _force;
174 #endif // !defined(PRODUCT)
175
176 public:
177 void init() PRODUCT_RETURN;
178 void update() PRODUCT_RETURN;
179 bool should_force() PRODUCT_RETURN_( return false; );
180 };
181
182 // this will enable a variety of different statistics per GC task
183 #define _MARKING_STATS_ 0
184 // this will enable the higher verbose levels
185 #define _MARKING_VERBOSE_ 0
186
187 #if _MARKING_STATS_
188 #define statsOnly(statement) \
189 do { \
190 statement ; \
191 } while (0)
192 #else // _MARKING_STATS_
193 #define statsOnly(statement) \
194 do { \
195 } while (0)
196 #endif // _MARKING_STATS_
197
198 typedef enum {
199 no_verbose = 0, // verbose turned off
200 stats_verbose, // only prints stats at the end of marking
201 low_verbose, // low verbose, mostly per region and per major event
202 medium_verbose, // a bit more detailed than low
203 high_verbose // per object verbose
204 } CMVerboseLevel;
205
206 class YoungList;
207
208 // Root Regions are regions that are not empty at the beginning of a
209 // marking cycle and which we might collect during an evacuation pause
210 // while the cycle is active. Given that, during evacuation pauses, we
211 // do not copy objects that are explicitly marked, what we have to do
212 // for the root regions is to scan them and mark all objects reachable
213 // from them. According to the SATB assumptions, we only need to visit
214 // each object once during marking. So, as long as we finish this scan
215 // before the next evacuation pause, we can copy the objects from the
216 // root regions without having to mark them or do anything else to them.
217 //
218 // Currently, we only support root region scanning once (at the start
219 // of the marking cycle) and the root regions are all the survivor
220 // regions populated during the initial-mark pause.
221 class CMRootRegions VALUE_OBJ_CLASS_SPEC {
222 private:
223 YoungList* _young_list;
224 ConcurrentMark* _cm;
225
226 volatile bool _scan_in_progress;
227 volatile bool _should_abort;
228 HeapRegion* volatile _next_survivor;
229
230 public:
231 CMRootRegions();
232 // We actually do most of the initialization in this method.
233 void init(G1CollectedHeap* g1h, ConcurrentMark* cm);
234
235 // Reset the claiming / scanning of the root regions.
236 void prepare_for_scan();
237
238 // Forces get_next() to return NULL so that the iteration aborts early.
239 void abort() { _should_abort = true; }
240
241 // Return true if the CM thread are actively scanning root regions,
242 // false otherwise.
243 bool scan_in_progress() { return _scan_in_progress; }
244
245 // Claim the next root region to scan atomically, or return NULL if
246 // all have been claimed.
247 HeapRegion* claim_next();
248
249 // Flag that we're done with root region scanning and notify anyone
250 // who's waiting on it. If aborted is false, assume that all regions
251 // have been claimed.
252 void scan_finished();
253
254 // If CM threads are still scanning root regions, wait until they
255 // are done. Return true if we had to wait, false otherwise.
256 bool wait_until_scan_finished();
257 };
258
259 class ConcurrentMarkThread;
260
261 class ConcurrentMark: public CHeapObj<mtGC> {
262 friend class CMMarkStack;
263 friend class ConcurrentMarkThread;
264 friend class CMTask;
265 friend class CMBitMapClosure;
266 friend class CMRemarkTask;
267 friend class CMConcurrentMarkingTask;
268 friend class G1ParNoteEndTask;
269 friend class CalcLiveObjectsClosure;
270 friend class G1CMRefProcTaskProxy;
271 friend class G1CMRefProcTaskExecutor;
272 friend class G1CMKeepAliveAndDrainClosure;
273 friend class G1CMDrainMarkingStackClosure;
274
275 protected:
276 ConcurrentMarkThread* _cmThread; // The thread doing the work
277 G1CollectedHeap* _g1h; // The heap
278 uint _parallel_marking_threads; // The number of marking
279 // threads we're using
280 uint _max_parallel_marking_threads; // Max number of marking
281 // threads we'll ever use
282 double _sleep_factor; // How much we have to sleep, with
283 // respect to the work we just did, to
284 // meet the marking overhead goal
285 double _marking_task_overhead; // Marking target overhead for
286 // a single task
287
288 // Same as the two above, but for the cleanup task
289 double _cleanup_sleep_factor;
290 double _cleanup_task_overhead;
291
292 FreeRegionList _cleanup_list;
293
294 // Concurrent marking support structures
295 G1CMBitMap _markBitMap1;
296 G1CMBitMap _markBitMap2;
297 CMBitMapRO* _prevMarkBitMap; // Completed mark bitmap
298 CMBitMap* _nextMarkBitMap; // Under-construction mark bitmap
299
300 BitMap _region_bm;
301 BitMap _card_bm;
302
303 // Heap bounds
304 HeapWord* _heap_start;
305 HeapWord* _heap_end;
306
307 // Root region tracking and claiming
308 CMRootRegions _root_regions;
309
310 // For gray objects
311 CMMarkStack _markStack; // Grey objects behind global finger
312 HeapWord* volatile _finger; // The global finger, region aligned,
313 // always points to the end of the
314 // last claimed region
315
316 // Marking tasks
317 uint _max_worker_id;// Maximum worker id
318 uint _active_tasks; // Task num currently active
319 CMTask** _tasks; // Task queue array (max_worker_id len)
320 CMTaskQueueSet* _task_queues; // Task queue set
321 ParallelTaskTerminator _terminator; // For termination
322
323 // Two sync barriers that are used to synchronize tasks when an
324 // overflow occurs. The algorithm is the following. All tasks enter
325 // the first one to ensure that they have all stopped manipulating
326 // the global data structures. After they exit it, they re-initialize
327 // their data structures and task 0 re-initializes the global data
328 // structures. Then, they enter the second sync barrier. This
329 // ensure, that no task starts doing work before all data
330 // structures (local and global) have been re-initialized. When they
331 // exit it, they are free to start working again.
332 WorkGangBarrierSync _first_overflow_barrier_sync;
333 WorkGangBarrierSync _second_overflow_barrier_sync;
334
335 // This is set by any task, when an overflow on the global data
336 // structures is detected
337 volatile bool _has_overflown;
338 // True: marking is concurrent, false: we're in remark
339 volatile bool _concurrent;
340 // Set at the end of a Full GC so that marking aborts
341 volatile bool _has_aborted;
342 GCId _aborted_gc_id;
343
344 // Used when remark aborts due to an overflow to indicate that
345 // another concurrent marking phase should start
346 volatile bool _restart_for_overflow;
347
348 // This is true from the very start of concurrent marking until the
349 // point when all the tasks complete their work. It is really used
350 // to determine the points between the end of concurrent marking and
351 // time of remark.
352 volatile bool _concurrent_marking_in_progress;
353
354 // Verbose level
355 CMVerboseLevel _verbose_level;
356
357 // All of these times are in ms
358 NumberSeq _init_times;
359 NumberSeq _remark_times;
360 NumberSeq _remark_mark_times;
361 NumberSeq _remark_weak_ref_times;
362 NumberSeq _cleanup_times;
363 double _total_counting_time;
364 double _total_rs_scrub_time;
365
366 double* _accum_task_vtime; // Accumulated task vtime
367
368 WorkGang* _parallel_workers;
369
370 ForceOverflowSettings _force_overflow_conc;
371 ForceOverflowSettings _force_overflow_stw;
372
373 void weakRefsWorkParallelPart(BoolObjectClosure* is_alive, bool purged_classes);
374 void weakRefsWork(bool clear_all_soft_refs);
375
376 void swapMarkBitMaps();
377
378 // It resets the global marking data structures, as well as the
379 // task local ones; should be called during initial mark.
380 void reset();
381
382 // Resets all the marking data structures. Called when we have to restart
383 // marking or when marking completes (via set_non_marking_state below).
384 void reset_marking_state(bool clear_overflow = true);
385
386 // We do this after we're done with marking so that the marking data
387 // structures are initialized to a sensible and predictable state.
388 void set_non_marking_state();
389
390 // Called to indicate how many threads are currently active.
391 void set_concurrency(uint active_tasks);
392
393 // It should be called to indicate which phase we're in (concurrent
394 // mark or remark) and how many threads are currently active.
395 void set_concurrency_and_phase(uint active_tasks, bool concurrent);
396
397 // Prints all gathered CM-related statistics
398 void print_stats();
399
400 bool cleanup_list_is_empty() {
401 return _cleanup_list.is_empty();
402 }
403
404 // Accessor methods
405 uint parallel_marking_threads() const { return _parallel_marking_threads; }
406 uint max_parallel_marking_threads() const { return _max_parallel_marking_threads;}
407 double sleep_factor() { return _sleep_factor; }
408 double marking_task_overhead() { return _marking_task_overhead;}
409 double cleanup_sleep_factor() { return _cleanup_sleep_factor; }
410 double cleanup_task_overhead() { return _cleanup_task_overhead;}
411
412 HeapWord* finger() { return _finger; }
413 bool concurrent() { return _concurrent; }
414 uint active_tasks() { return _active_tasks; }
415 ParallelTaskTerminator* terminator() { return &_terminator; }
416
417 // It claims the next available region to be scanned by a marking
418 // task/thread. It might return NULL if the next region is empty or
419 // we have run out of regions. In the latter case, out_of_regions()
420 // determines whether we've really run out of regions or the task
421 // should call claim_region() again. This might seem a bit
422 // awkward. Originally, the code was written so that claim_region()
423 // either successfully returned with a non-empty region or there
424 // were no more regions to be claimed. The problem with this was
425 // that, in certain circumstances, it iterated over large chunks of
426 // the heap finding only empty regions and, while it was working, it
427 // was preventing the calling task to call its regular clock
428 // method. So, this way, each task will spend very little time in
429 // claim_region() and is allowed to call the regular clock method
430 // frequently.
431 HeapRegion* claim_region(uint worker_id);
432
433 // It determines whether we've run out of regions to scan. Note that
434 // the finger can point past the heap end in case the heap was expanded
435 // to satisfy an allocation without doing a GC. This is fine, because all
436 // objects in those regions will be considered live anyway because of
437 // SATB guarantees (i.e. their TAMS will be equal to bottom).
438 bool out_of_regions() { return _finger >= _heap_end; }
439
440 // Returns the task with the given id
441 CMTask* task(int id) {
442 assert(0 <= id && id < (int) _active_tasks,
443 "task id not within active bounds");
444 return _tasks[id];
445 }
446
447 // Returns the task queue with the given id
448 CMTaskQueue* task_queue(int id) {
449 assert(0 <= id && id < (int) _active_tasks,
450 "task queue id not within active bounds");
451 return (CMTaskQueue*) _task_queues->queue(id);
452 }
453
454 // Returns the task queue set
455 CMTaskQueueSet* task_queues() { return _task_queues; }
456
457 // Access / manipulation of the overflow flag which is set to
458 // indicate that the global stack has overflown
459 bool has_overflown() { return _has_overflown; }
460 void set_has_overflown() { _has_overflown = true; }
461 void clear_has_overflown() { _has_overflown = false; }
462 bool restart_for_overflow() { return _restart_for_overflow; }
463
464 // Methods to enter the two overflow sync barriers
465 void enter_first_sync_barrier(uint worker_id);
466 void enter_second_sync_barrier(uint worker_id);
467
468 ForceOverflowSettings* force_overflow_conc() {
469 return &_force_overflow_conc;
470 }
471
472 ForceOverflowSettings* force_overflow_stw() {
473 return &_force_overflow_stw;
474 }
475
476 ForceOverflowSettings* force_overflow() {
477 if (concurrent()) {
478 return force_overflow_conc();
479 } else {
480 return force_overflow_stw();
481 }
482 }
483
484 // Live Data Counting data structures...
485 // These data structures are initialized at the start of
486 // marking. They are written to while marking is active.
487 // They are aggregated during remark; the aggregated values
488 // are then used to populate the _region_bm, _card_bm, and
489 // the total live bytes, which are then subsequently updated
490 // during cleanup.
491
492 // An array of bitmaps (one bit map per task). Each bitmap
493 // is used to record the cards spanned by the live objects
494 // marked by that task/worker.
495 BitMap* _count_card_bitmaps;
496
497 // Used to record the number of marked live bytes
498 // (for each region, by worker thread).
499 size_t** _count_marked_bytes;
500
501 // Card index of the bottom of the G1 heap. Used for biasing indices into
502 // the card bitmaps.
503 intptr_t _heap_bottom_card_num;
504
505 // Set to true when initialization is complete
506 bool _completed_initialization;
507
508 public:
509 // Manipulation of the global mark stack.
510 // The push and pop operations are used by tasks for transfers
511 // between task-local queues and the global mark stack, and use
512 // locking for concurrency safety.
513 bool mark_stack_push(oop* arr, int n) {
514 _markStack.par_push_arr(arr, n);
515 if (_markStack.overflow()) {
516 set_has_overflown();
517 return false;
518 }
519 return true;
520 }
521 void mark_stack_pop(oop* arr, int max, int* n) {
522 _markStack.par_pop_arr(arr, max, n);
523 }
524 size_t mark_stack_size() { return _markStack.size(); }
525 size_t partial_mark_stack_size_target() { return _markStack.maxElems()/3; }
526 bool mark_stack_overflow() { return _markStack.overflow(); }
527 bool mark_stack_empty() { return _markStack.isEmpty(); }
528
529 CMRootRegions* root_regions() { return &_root_regions; }
530
531 bool concurrent_marking_in_progress() {
532 return _concurrent_marking_in_progress;
533 }
534 void set_concurrent_marking_in_progress() {
535 _concurrent_marking_in_progress = true;
536 }
537 void clear_concurrent_marking_in_progress() {
538 _concurrent_marking_in_progress = false;
539 }
540
541 void update_accum_task_vtime(int i, double vtime) {
542 _accum_task_vtime[i] += vtime;
543 }
544
545 double all_task_accum_vtime() {
546 double ret = 0.0;
547 for (uint i = 0; i < _max_worker_id; ++i)
548 ret += _accum_task_vtime[i];
549 return ret;
550 }
551
552 // Attempts to steal an object from the task queues of other tasks
553 bool try_stealing(uint worker_id, int* hash_seed, oop& obj);
554
555 ConcurrentMark(G1CollectedHeap* g1h,
556 G1RegionToSpaceMapper* prev_bitmap_storage,
557 G1RegionToSpaceMapper* next_bitmap_storage);
558 ~ConcurrentMark();
559
560 ConcurrentMarkThread* cmThread() { return _cmThread; }
561
562 CMBitMapRO* prevMarkBitMap() const { return _prevMarkBitMap; }
563 CMBitMap* nextMarkBitMap() const { return _nextMarkBitMap; }
564
565 // Returns the number of GC threads to be used in a concurrent
566 // phase based on the number of GC threads being used in a STW
567 // phase.
568 uint scale_parallel_threads(uint n_par_threads);
569
570 // Calculates the number of GC threads to be used in a concurrent phase.
571 uint calc_parallel_marking_threads();
572
573 // The following three are interaction between CM and
574 // G1CollectedHeap
575
576 // This notifies CM that a root during initial-mark needs to be
577 // grayed. It is MT-safe. word_size is the size of the object in
578 // words. It is passed explicitly as sometimes we cannot calculate
579 // it from the given object because it might be in an inconsistent
580 // state (e.g., in to-space and being copied). So the caller is
581 // responsible for dealing with this issue (e.g., get the size from
582 // the from-space image when the to-space image might be
583 // inconsistent) and always passing the size. hr is the region that
584 // contains the object and it's passed optionally from callers who
585 // might already have it (no point in recalculating it).
586 inline void grayRoot(oop obj,
587 size_t word_size,
588 uint worker_id,
589 HeapRegion* hr = NULL);
590
591 // It iterates over the heap and for each object it comes across it
592 // will dump the contents of its reference fields, as well as
593 // liveness information for the object and its referents. The dump
594 // will be written to a file with the following name:
595 // G1PrintReachableBaseFile + "." + str.
596 // vo decides whether the prev (vo == UsePrevMarking), the next
597 // (vo == UseNextMarking) marking information, or the mark word
598 // (vo == UseMarkWord) will be used to determine the liveness of
599 // each object / referent.
600 // If all is true, all objects in the heap will be dumped, otherwise
601 // only the live ones. In the dump the following symbols / breviations
602 // are used:
603 // M : an explicitly live object (its bitmap bit is set)
604 // > : an implicitly live object (over tams)
605 // O : an object outside the G1 heap (typically: in the perm gen)
606 // NOT : a reference field whose referent is not live
607 // AND MARKED : indicates that an object is both explicitly and
608 // implicitly live (it should be one or the other, not both)
609 void print_reachable(const char* str,
610 VerifyOption vo,
611 bool all) PRODUCT_RETURN;
612
613 // Clear the next marking bitmap (will be called concurrently).
614 void clearNextBitmap();
615
616 // Return whether the next mark bitmap has no marks set. To be used for assertions
617 // only. Will not yield to pause requests.
618 bool nextMarkBitmapIsClear();
619
620 // These two do the work that needs to be done before and after the
621 // initial root checkpoint. Since this checkpoint can be done at two
622 // different points (i.e. an explicit pause or piggy-backed on a
623 // young collection), then it's nice to be able to easily share the
624 // pre/post code. It might be the case that we can put everything in
625 // the post method. TP
626 void checkpointRootsInitialPre();
627 void checkpointRootsInitialPost();
628
629 // Scan all the root regions and mark everything reachable from
630 // them.
631 void scanRootRegions();
632
633 // Scan a single root region and mark everything reachable from it.
634 void scanRootRegion(HeapRegion* hr, uint worker_id);
635
636 // Do concurrent phase of marking, to a tentative transitive closure.
637 void markFromRoots();
638
639 void checkpointRootsFinal(bool clear_all_soft_refs);
640 void checkpointRootsFinalWork();
641 void cleanup();
642 void completeCleanup();
643
644 // Mark in the previous bitmap. NB: this is usually read-only, so use
645 // this carefully!
646 inline void markPrev(oop p);
647
648 // Clears marks for all objects in the given range, for the prev or
649 // next bitmaps. NB: the previous bitmap is usually
650 // read-only, so use this carefully!
651 void clearRangePrevBitmap(MemRegion mr);
652 void clearRangeNextBitmap(MemRegion mr);
653
654 // Notify data structures that a GC has started.
655 void note_start_of_gc() {
656 _markStack.note_start_of_gc();
657 }
658
659 // Notify data structures that a GC is finished.
660 void note_end_of_gc() {
661 _markStack.note_end_of_gc();
662 }
663
664 // Verify that there are no CSet oops on the stacks (taskqueues /
665 // global mark stack) and fingers (global / per-task).
666 // If marking is not in progress, it's a no-op.
667 void verify_no_cset_oops() PRODUCT_RETURN;
668
669 bool isPrevMarked(oop p) const {
670 assert(p != NULL && p->is_oop(), "expected an oop");
671 HeapWord* addr = (HeapWord*)p;
672 assert(addr >= _prevMarkBitMap->startWord() ||
673 addr < _prevMarkBitMap->endWord(), "in a region");
674
675 return _prevMarkBitMap->isMarked(addr);
676 }
677
678 inline bool do_yield_check(uint worker_i = 0);
679
680 // Called to abort the marking cycle after a Full GC takes place.
681 void abort();
682
683 bool has_aborted() { return _has_aborted; }
684
685 const GCId& concurrent_gc_id();
686
687 // This prints the global/local fingers. It is used for debugging.
688 NOT_PRODUCT(void print_finger();)
689
690 void print_summary_info();
691
692 void print_worker_threads_on(outputStream* st) const;
693
694 void print_on_error(outputStream* st) const;
695
696 // The following indicate whether a given verbose level has been
697 // set. Notice that anything above stats is conditional to
698 // _MARKING_VERBOSE_ having been set to 1
699 bool verbose_stats() {
700 return _verbose_level >= stats_verbose;
701 }
702 bool verbose_low() {
703 return _MARKING_VERBOSE_ && _verbose_level >= low_verbose;
704 }
705 bool verbose_medium() {
706 return _MARKING_VERBOSE_ && _verbose_level >= medium_verbose;
707 }
708 bool verbose_high() {
709 return _MARKING_VERBOSE_ && _verbose_level >= high_verbose;
710 }
711
712 // Liveness counting
713
714 // Utility routine to set an exclusive range of cards on the given
715 // card liveness bitmap
716 inline void set_card_bitmap_range(BitMap* card_bm,
717 BitMap::idx_t start_idx,
718 BitMap::idx_t end_idx,
719 bool is_par);
720
721 // Returns the card number of the bottom of the G1 heap.
722 // Used in biasing indices into accounting card bitmaps.
723 intptr_t heap_bottom_card_num() const {
724 return _heap_bottom_card_num;
725 }
726
727 // Returns the card bitmap for a given task or worker id.
728 BitMap* count_card_bitmap_for(uint worker_id) {
729 assert(worker_id < _max_worker_id, "oob");
730 assert(_count_card_bitmaps != NULL, "uninitialized");
731 BitMap* task_card_bm = &_count_card_bitmaps[worker_id];
732 assert(task_card_bm->size() == _card_bm.size(), "size mismatch");
733 return task_card_bm;
734 }
735
736 // Returns the array containing the marked bytes for each region,
737 // for the given worker or task id.
738 size_t* count_marked_bytes_array_for(uint worker_id) {
739 assert(worker_id < _max_worker_id, "oob");
740 assert(_count_marked_bytes != NULL, "uninitialized");
741 size_t* marked_bytes_array = _count_marked_bytes[worker_id];
742 assert(marked_bytes_array != NULL, "uninitialized");
743 return marked_bytes_array;
744 }
745
746 // Returns the index in the liveness accounting card table bitmap
747 // for the given address
748 inline BitMap::idx_t card_bitmap_index_for(HeapWord* addr);
749
750 // Counts the size of the given memory region in the the given
751 // marked_bytes array slot for the given HeapRegion.
752 // Sets the bits in the given card bitmap that are associated with the
753 // cards that are spanned by the memory region.
754 inline void count_region(MemRegion mr,
755 HeapRegion* hr,
756 size_t* marked_bytes_array,
757 BitMap* task_card_bm);
758
759 // Counts the given memory region in the task/worker counting
760 // data structures for the given worker id.
761 inline void count_region(MemRegion mr, HeapRegion* hr, uint worker_id);
762
763 // Counts the given object in the given task/worker counting
764 // data structures.
765 inline void count_object(oop obj,
766 HeapRegion* hr,
767 size_t* marked_bytes_array,
768 BitMap* task_card_bm);
769
770 // Attempts to mark the given object and, if successful, counts
771 // the object in the given task/worker counting structures.
772 inline bool par_mark_and_count(oop obj,
773 HeapRegion* hr,
774 size_t* marked_bytes_array,
775 BitMap* task_card_bm);
776
777 // Attempts to mark the given object and, if successful, counts
778 // the object in the task/worker counting structures for the
779 // given worker id.
780 inline bool par_mark_and_count(oop obj,
781 size_t word_size,
782 HeapRegion* hr,
783 uint worker_id);
784
785 // Returns true if initialization was successfully completed.
786 bool completed_initialization() const {
787 return _completed_initialization;
788 }
789
790 protected:
791 // Clear all the per-task bitmaps and arrays used to store the
792 // counting data.
793 void clear_all_count_data();
794
795 // Aggregates the counting data for each worker/task
796 // that was constructed while marking. Also sets
797 // the amount of marked bytes for each region and
798 // the top at concurrent mark count.
799 void aggregate_count_data();
800
801 // Verification routine
802 void verify_count_data();
803 };
804
805 // A class representing a marking task.
806 class CMTask : public TerminatorTerminator {
807 private:
808 enum PrivateConstants {
809 // the regular clock call is called once the scanned words reaches
810 // this limit
811 words_scanned_period = 12*1024,
812 // the regular clock call is called once the number of visited
813 // references reaches this limit
814 refs_reached_period = 384,
815 // initial value for the hash seed, used in the work stealing code
816 init_hash_seed = 17,
817 // how many entries will be transferred between global stack and
818 // local queues
819 global_stack_transfer_size = 16
820 };
821
822 uint _worker_id;
823 G1CollectedHeap* _g1h;
824 ConcurrentMark* _cm;
825 CMBitMap* _nextMarkBitMap;
826 // the task queue of this task
827 CMTaskQueue* _task_queue;
828 private:
829 // the task queue set---needed for stealing
830 CMTaskQueueSet* _task_queues;
831 // indicates whether the task has been claimed---this is only for
832 // debugging purposes
833 bool _claimed;
834
835 // number of calls to this task
836 int _calls;
837
838 // when the virtual timer reaches this time, the marking step should
839 // exit
840 double _time_target_ms;
841 // the start time of the current marking step
842 double _start_time_ms;
843
844 // the oop closure used for iterations over oops
845 G1CMOopClosure* _cm_oop_closure;
846
847 // the region this task is scanning, NULL if we're not scanning any
848 HeapRegion* _curr_region;
849 // the local finger of this task, NULL if we're not scanning a region
850 HeapWord* _finger;
851 // limit of the region this task is scanning, NULL if we're not scanning one
852 HeapWord* _region_limit;
853
854 // the number of words this task has scanned
855 size_t _words_scanned;
856 // When _words_scanned reaches this limit, the regular clock is
857 // called. Notice that this might be decreased under certain
858 // circumstances (i.e. when we believe that we did an expensive
859 // operation).
860 size_t _words_scanned_limit;
861 // the initial value of _words_scanned_limit (i.e. what it was
862 // before it was decreased).
863 size_t _real_words_scanned_limit;
864
865 // the number of references this task has visited
866 size_t _refs_reached;
867 // When _refs_reached reaches this limit, the regular clock is
868 // called. Notice this this might be decreased under certain
869 // circumstances (i.e. when we believe that we did an expensive
870 // operation).
871 size_t _refs_reached_limit;
872 // the initial value of _refs_reached_limit (i.e. what it was before
873 // it was decreased).
874 size_t _real_refs_reached_limit;
875
876 // used by the work stealing stuff
877 int _hash_seed;
878 // if this is true, then the task has aborted for some reason
879 bool _has_aborted;
880 // set when the task aborts because it has met its time quota
881 bool _has_timed_out;
882 // true when we're draining SATB buffers; this avoids the task
883 // aborting due to SATB buffers being available (as we're already
884 // dealing with them)
885 bool _draining_satb_buffers;
886
887 // number sequence of past step times
888 NumberSeq _step_times_ms;
889 // elapsed time of this task
890 double _elapsed_time_ms;
891 // termination time of this task
892 double _termination_time_ms;
893 // when this task got into the termination protocol
894 double _termination_start_time_ms;
895
896 // true when the task is during a concurrent phase, false when it is
897 // in the remark phase (so, in the latter case, we do not have to
898 // check all the things that we have to check during the concurrent
899 // phase, i.e. SATB buffer availability...)
900 bool _concurrent;
901
902 TruncatedSeq _marking_step_diffs_ms;
903
904 // Counting data structures. Embedding the task's marked_bytes_array
905 // and card bitmap into the actual task saves having to go through
906 // the ConcurrentMark object.
907 size_t* _marked_bytes_array;
908 BitMap* _card_bm;
909
910 // LOTS of statistics related with this task
911 #if _MARKING_STATS_
912 NumberSeq _all_clock_intervals_ms;
913 double _interval_start_time_ms;
914
915 size_t _aborted;
916 size_t _aborted_overflow;
917 size_t _aborted_cm_aborted;
918 size_t _aborted_yield;
919 size_t _aborted_timed_out;
920 size_t _aborted_satb;
921 size_t _aborted_termination;
922
923 size_t _steal_attempts;
924 size_t _steals;
925
926 size_t _clock_due_to_marking;
927 size_t _clock_due_to_scanning;
928
929 size_t _local_pushes;
930 size_t _local_pops;
931 size_t _local_max_size;
932 size_t _objs_scanned;
933
934 size_t _global_pushes;
935 size_t _global_pops;
936 size_t _global_max_size;
937
938 size_t _global_transfers_to;
939 size_t _global_transfers_from;
940
941 size_t _regions_claimed;
942 size_t _objs_found_on_bitmap;
943
944 size_t _satb_buffers_processed;
945 #endif // _MARKING_STATS_
946
947 // it updates the local fields after this task has claimed
948 // a new region to scan
949 void setup_for_region(HeapRegion* hr);
950 // it brings up-to-date the limit of the region
951 void update_region_limit();
952
953 // called when either the words scanned or the refs visited limit
954 // has been reached
955 void reached_limit();
956 // recalculates the words scanned and refs visited limits
957 void recalculate_limits();
958 // decreases the words scanned and refs visited limits when we reach
959 // an expensive operation
960 void decrease_limits();
961 // it checks whether the words scanned or refs visited reached their
962 // respective limit and calls reached_limit() if they have
963 void check_limits() {
964 if (_words_scanned >= _words_scanned_limit ||
965 _refs_reached >= _refs_reached_limit) {
966 reached_limit();
967 }
968 }
969 // this is supposed to be called regularly during a marking step as
970 // it checks a bunch of conditions that might cause the marking step
971 // to abort
972 void regular_clock_call();
973 bool concurrent() { return _concurrent; }
974
975 // Test whether obj might have already been passed over by the
976 // mark bitmap scan, and so needs to be pushed onto the mark stack.
977 bool is_below_finger(oop obj, HeapWord* global_finger) const;
978
979 template<bool scan> void process_grey_object(oop obj);
980
981 public:
982 // It resets the task; it should be called right at the beginning of
983 // a marking phase.
984 void reset(CMBitMap* _nextMarkBitMap);
985 // it clears all the fields that correspond to a claimed region.
986 void clear_region_fields();
987
988 void set_concurrent(bool concurrent) { _concurrent = concurrent; }
989
990 // The main method of this class which performs a marking step
991 // trying not to exceed the given duration. However, it might exit
992 // prematurely, according to some conditions (i.e. SATB buffers are
993 // available for processing).
994 void do_marking_step(double target_ms,
995 bool do_termination,
996 bool is_serial);
997
998 // These two calls start and stop the timer
999 void record_start_time() {
1000 _elapsed_time_ms = os::elapsedTime() * 1000.0;
1001 }
1002 void record_end_time() {
1003 _elapsed_time_ms = os::elapsedTime() * 1000.0 - _elapsed_time_ms;
1004 }
1005
1006 // returns the worker ID associated with this task.
1007 uint worker_id() { return _worker_id; }
1008
1009 // From TerminatorTerminator. It determines whether this task should
1010 // exit the termination protocol after it's entered it.
1011 virtual bool should_exit_termination();
1012
1013 // Resets the local region fields after a task has finished scanning a
1014 // region; or when they have become stale as a result of the region
1015 // being evacuated.
1016 void giveup_current_region();
1017
1018 HeapWord* finger() { return _finger; }
1019
1020 bool has_aborted() { return _has_aborted; }
1021 void set_has_aborted() { _has_aborted = true; }
1022 void clear_has_aborted() { _has_aborted = false; }
1023 bool has_timed_out() { return _has_timed_out; }
1024 bool claimed() { return _claimed; }
1025
1026 void set_cm_oop_closure(G1CMOopClosure* cm_oop_closure);
1027
1028 // Increment the number of references this task has visited.
1029 void increment_refs_reached() { ++_refs_reached; }
1030
1031 // Grey the object by marking it. If not already marked, push it on
1032 // the local queue if below the finger.
1033 // Precondition: obj is in region.
1034 // Precondition: obj is below region's NTAMS.
1035 inline void make_reference_grey(oop obj, HeapRegion* region);
1036
1037 // Grey the object (by calling make_grey_reference) if required,
1038 // e.g. obj is below its containing region's NTAMS.
1039 // Precondition: obj is a valid heap object.
1040 inline void deal_with_reference(oop obj);
1041
1042 // It scans an object and visits its children.
1043 inline void scan_object(oop obj);
1044
1045 // It pushes an object on the local queue.
1046 inline void push(oop obj);
1047
1048 // These two move entries to/from the global stack.
1049 void move_entries_to_global_stack();
1050 void get_entries_from_global_stack();
1051
1052 // It pops and scans objects from the local queue. If partially is
1053 // true, then it stops when the queue size is of a given limit. If
1054 // partially is false, then it stops when the queue is empty.
1055 void drain_local_queue(bool partially);
1056 // It moves entries from the global stack to the local queue and
1057 // drains the local queue. If partially is true, then it stops when
1058 // both the global stack and the local queue reach a given size. If
1059 // partially if false, it tries to empty them totally.
1060 void drain_global_stack(bool partially);
1061 // It keeps picking SATB buffers and processing them until no SATB
1062 // buffers are available.
1063 void drain_satb_buffers();
1064
1065 // moves the local finger to a new location
1066 inline void move_finger_to(HeapWord* new_finger) {
1067 assert(new_finger >= _finger && new_finger < _region_limit, "invariant");
1068 _finger = new_finger;
1069 }
1070
1071 CMTask(uint worker_id,
1072 ConcurrentMark *cm,
1073 size_t* marked_bytes,
1074 BitMap* card_bm,
1075 CMTaskQueue* task_queue,
1076 CMTaskQueueSet* task_queues);
1077
1078 // it prints statistics associated with this task
1079 void print_stats();
1080
1081 #if _MARKING_STATS_
1082 void increase_objs_found_on_bitmap() { ++_objs_found_on_bitmap; }
1083 #endif // _MARKING_STATS_
1084 };
1085
1086 // Class that's used to to print out per-region liveness
1087 // information. It's currently used at the end of marking and also
1088 // after we sort the old regions at the end of the cleanup operation.
1089 class G1PrintRegionLivenessInfoClosure: public HeapRegionClosure {
1090 private:
1091 outputStream* _out;
1092
1093 // Accumulators for these values.
1094 size_t _total_used_bytes;
1095 size_t _total_capacity_bytes;
1096 size_t _total_prev_live_bytes;
1097 size_t _total_next_live_bytes;
1098
1099 // These are set up when we come across a "stars humongous" region
1100 // (as this is where most of this information is stored, not in the
1101 // subsequent "continues humongous" regions). After that, for every
1102 // region in a given humongous region series we deduce the right
1103 // values for it by simply subtracting the appropriate amount from
1104 // these fields. All these values should reach 0 after we've visited
1105 // the last region in the series.
1106 size_t _hum_used_bytes;
1107 size_t _hum_capacity_bytes;
1108 size_t _hum_prev_live_bytes;
1109 size_t _hum_next_live_bytes;
1110
1111 // Accumulator for the remembered set size
1112 size_t _total_remset_bytes;
1113
1114 // Accumulator for strong code roots memory size
1115 size_t _total_strong_code_roots_bytes;
1116
1117 static double perc(size_t val, size_t total) {
1118 if (total == 0) {
1119 return 0.0;
1120 } else {
1121 return 100.0 * ((double) val / (double) total);
1122 }
1123 }
1124
1125 static double bytes_to_mb(size_t val) {
1126 return (double) val / (double) M;
1127 }
1128
1129 // See the .cpp file.
1130 size_t get_hum_bytes(size_t* hum_bytes);
1131 void get_hum_bytes(size_t* used_bytes, size_t* capacity_bytes,
1132 size_t* prev_live_bytes, size_t* next_live_bytes);
1133
1134 public:
1135 // The header and footer are printed in the constructor and
1136 // destructor respectively.
1137 G1PrintRegionLivenessInfoClosure(outputStream* out, const char* phase_name);
1138 virtual bool doHeapRegion(HeapRegion* r);
1139 ~G1PrintRegionLivenessInfoClosure();
1140 };
1141
1142 #endif // SHARE_VM_GC_G1_CONCURRENTMARK_HPP