249 // all have been claimed.
250 HeapRegion* claim_next();
251
252 void cancel_scan();
253
254 // Flag that we're done with root region scanning and notify anyone
255 // who's waiting on it. If aborted is false, assume that all regions
256 // have been claimed.
257 void scan_finished();
258
259 // If CM threads are still scanning root regions, wait until they
260 // are done. Return true if we had to wait, false otherwise.
261 bool wait_until_scan_finished();
262 };
263
264 class ConcurrentMarkThread;
265
266 class G1ConcurrentMark: public CHeapObj<mtGC> {
267 friend class ConcurrentMarkThread;
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 friend class G1CMBitMapClosure;
275 friend class G1CMConcurrentMarkingTask;
276 friend class G1CMMarkStack;
277 friend class G1CMRemarkTask;
278 friend class G1CMTask;
279
280 protected:
281 ConcurrentMarkThread* _cmThread; // The thread doing the work
282 G1CollectedHeap* _g1h; // The heap
283 uint _parallel_marking_threads; // The number of marking
284 // threads we're using
285 uint _max_parallel_marking_threads; // Max number of marking
286 // threads we'll ever use
287 double _sleep_factor; // How much we have to sleep, with
288 // respect to the work we just did, to
289 // meet the marking overhead goal
290 double _marking_task_overhead; // Marking target overhead for
291 // a single task
292
293 FreeRegionList _cleanup_list;
294
295 // Concurrent marking support structures
296 G1CMBitMap _markBitMap1;
297 G1CMBitMap _markBitMap2;
298 G1CMBitMapRO* _prevMarkBitMap; // Completed mark bitmap
299 G1CMBitMap* _nextMarkBitMap; // Under-construction mark bitmap
300
301 BitMap _region_bm;
302 BitMap _card_bm;
303
304 // Heap bounds
305 HeapWord* _heap_start;
306 HeapWord* _heap_end;
307
308 // Root region tracking and claiming
309 G1CMRootRegions _root_regions;
310
311 // For gray objects
312 G1CMMarkStack _markStack; // Grey objects behind global finger
313 HeapWord* volatile _finger; // The global finger, region aligned,
314 // always points to the end of the
315 // last claimed region
316
317 // Marking tasks
318 uint _max_worker_id;// Maximum worker id
319 uint _active_tasks; // Task num currently active
320 G1CMTask** _tasks; // Task queue array (max_worker_id len)
321 G1CMTaskQueueSet* _task_queues; // Task queue set
322 ParallelTaskTerminator _terminator; // For termination
356 G1OldTracer* _gc_tracer_cm;
357
358 // All of these times are in ms
359 NumberSeq _init_times;
360 NumberSeq _remark_times;
361 NumberSeq _remark_mark_times;
362 NumberSeq _remark_weak_ref_times;
363 NumberSeq _cleanup_times;
364 double _total_counting_time;
365 double _total_rs_scrub_time;
366
367 double* _accum_task_vtime; // Accumulated task vtime
368
369 WorkGang* _parallel_workers;
370
371 void weakRefsWorkParallelPart(BoolObjectClosure* is_alive, bool purged_classes);
372 void weakRefsWork(bool clear_all_soft_refs);
373
374 void swapMarkBitMaps();
375
376 // It resets the global marking data structures, as well as the
377 // task local ones; should be called during initial mark.
378 void reset();
379
380 // Resets all the marking data structures. Called when we have to restart
381 // marking or when marking completes (via set_non_marking_state below).
382 void reset_marking_state(bool clear_overflow = true);
383
384 // We do this after we're done with marking so that the marking data
385 // structures are initialized to a sensible and predictable state.
386 void set_non_marking_state();
387
388 // Called to indicate how many threads are currently active.
389 void set_concurrency(uint active_tasks);
390
391 // It should be called to indicate which phase we're in (concurrent
392 // mark or remark) and how many threads are currently active.
393 void set_concurrency_and_phase(uint active_tasks, bool concurrent);
394
395 // Prints all gathered CM-related statistics
444 G1CMTaskQueue* task_queue(int id) {
445 assert(0 <= id && id < (int) _active_tasks,
446 "task queue id not within active bounds");
447 return (G1CMTaskQueue*) _task_queues->queue(id);
448 }
449
450 // Returns the task queue set
451 G1CMTaskQueueSet* task_queues() { return _task_queues; }
452
453 // Access / manipulation of the overflow flag which is set to
454 // indicate that the global stack has overflown
455 bool has_overflown() { return _has_overflown; }
456 void set_has_overflown() { _has_overflown = true; }
457 void clear_has_overflown() { _has_overflown = false; }
458 bool restart_for_overflow() { return _restart_for_overflow; }
459
460 // Methods to enter the two overflow sync barriers
461 void enter_first_sync_barrier(uint worker_id);
462 void enter_second_sync_barrier(uint worker_id);
463
464 // Live Data Counting data structures...
465 // These data structures are initialized at the start of
466 // marking. They are written to while marking is active.
467 // They are aggregated during remark; the aggregated values
468 // are then used to populate the _region_bm, _card_bm, and
469 // the total live bytes, which are then subsequently updated
470 // during cleanup.
471
472 // An array of bitmaps (one bit map per task). Each bitmap
473 // is used to record the cards spanned by the live objects
474 // marked by that task/worker.
475 BitMap* _count_card_bitmaps;
476
477 // Used to record the number of marked live bytes
478 // (for each region, by worker thread).
479 size_t** _count_marked_bytes;
480
481 // Card index of the bottom of the G1 heap. Used for biasing indices into
482 // the card bitmaps.
483 intptr_t _heap_bottom_card_num;
484
485 // Set to true when initialization is complete
486 bool _completed_initialization;
487
488 // end_timer, true to end gc timer after ending concurrent phase.
489 void register_concurrent_phase_end_common(bool end_timer);
490
491 // Clear the given bitmap in parallel using the given WorkGang. If may_yield is
492 // true, periodically insert checks to see if this method should exit prematurely.
493 void clear_bitmap(G1CMBitMap* bitmap, WorkGang* workers, bool may_yield);
494 public:
495 // Manipulation of the global mark stack.
496 // The push and pop operations are used by tasks for transfers
497 // between task-local queues and the global mark stack, and use
498 // locking for concurrency safety.
499 bool mark_stack_push(oop* arr, int n) {
500 _markStack.par_push_arr(arr, n);
546 G1RegionToSpaceMapper* next_bitmap_storage);
547 ~G1ConcurrentMark();
548
549 ConcurrentMarkThread* cmThread() { return _cmThread; }
550
551 G1CMBitMapRO* prevMarkBitMap() const { return _prevMarkBitMap; }
552 G1CMBitMap* nextMarkBitMap() const { return _nextMarkBitMap; }
553
554 // Returns the number of GC threads to be used in a concurrent
555 // phase based on the number of GC threads being used in a STW
556 // phase.
557 uint scale_parallel_threads(uint n_par_threads);
558
559 // Calculates the number of GC threads to be used in a concurrent phase.
560 uint calc_parallel_marking_threads();
561
562 // The following three are interaction between CM and
563 // G1CollectedHeap
564
565 // This notifies CM that a root during initial-mark needs to be
566 // grayed. It is MT-safe. word_size is the size of the object in
567 // words. It is passed explicitly as sometimes we cannot calculate
568 // it from the given object because it might be in an inconsistent
569 // state (e.g., in to-space and being copied). So the caller is
570 // responsible for dealing with this issue (e.g., get the size from
571 // the from-space image when the to-space image might be
572 // inconsistent) and always passing the size. hr is the region that
573 // contains the object and it's passed optionally from callers who
574 // might already have it (no point in recalculating it).
575 inline void grayRoot(oop obj,
576 size_t word_size,
577 uint worker_id,
578 HeapRegion* hr = NULL);
579
580 // Prepare internal data structures for the next mark cycle. This includes clearing
581 // the next mark bitmap and some internal data structures. This method is intended
582 // to be called concurrently to the mutator. It will yield to safepoint requests.
583 void cleanup_for_next_mark();
584
585 // Clear the previous marking bitmap during safepoint.
586 void clear_prev_bitmap(WorkGang* workers);
587
588 // Return whether the next mark bitmap has no marks set. To be used for assertions
589 // only. Will not yield to pause requests.
590 bool nextMarkBitmapIsClear();
591
592 // These two do the work that needs to be done before and after the
593 // initial root checkpoint. Since this checkpoint can be done at two
594 // different points (i.e. an explicit pause or piggy-backed on a
595 // young collection), then it's nice to be able to easily share the
596 // pre/post code. It might be the case that we can put everything in
597 // the post method. TP
624
625 // Notify data structures that a GC has started.
626 void note_start_of_gc() {
627 _markStack.note_start_of_gc();
628 }
629
630 // Notify data structures that a GC is finished.
631 void note_end_of_gc() {
632 _markStack.note_end_of_gc();
633 }
634
635 // Verify that there are no CSet oops on the stacks (taskqueues /
636 // global mark stack) and fingers (global / per-task).
637 // If marking is not in progress, it's a no-op.
638 void verify_no_cset_oops() PRODUCT_RETURN;
639
640 inline bool isPrevMarked(oop p) const;
641
642 inline bool do_yield_check(uint worker_i = 0);
643
644 // Called to abort the marking cycle after a Full GC takes place.
645 void abort();
646
647 bool has_aborted() { return _has_aborted; }
648
649 void print_summary_info();
650
651 void print_worker_threads_on(outputStream* st) const;
652
653 void print_on_error(outputStream* st) const;
654
655 // Liveness counting
656
657 // Utility routine to set an exclusive range of cards on the given
658 // card liveness bitmap
659 inline void set_card_bitmap_range(BitMap* card_bm,
660 BitMap::idx_t start_idx,
661 BitMap::idx_t end_idx,
662 bool is_par);
663
664 // Returns the card number of the bottom of the G1 heap.
665 // Used in biasing indices into accounting card bitmaps.
666 intptr_t heap_bottom_card_num() const {
667 return _heap_bottom_card_num;
668 }
669
670 // Returns the card bitmap for a given task or worker id.
671 BitMap* count_card_bitmap_for(uint worker_id) {
672 assert(worker_id < _max_worker_id, "oob");
673 assert(_count_card_bitmaps != NULL, "uninitialized");
674 BitMap* task_card_bm = &_count_card_bitmaps[worker_id];
675 assert(task_card_bm->size() == _card_bm.size(), "size mismatch");
676 return task_card_bm;
677 }
678
679 // Returns the array containing the marked bytes for each region,
680 // for the given worker or task id.
681 size_t* count_marked_bytes_array_for(uint worker_id) {
682 assert(worker_id < _max_worker_id, "oob");
683 assert(_count_marked_bytes != NULL, "uninitialized");
684 size_t* marked_bytes_array = _count_marked_bytes[worker_id];
685 assert(marked_bytes_array != NULL, "uninitialized");
686 return marked_bytes_array;
687 }
688
689 // Returns the index in the liveness accounting card table bitmap
690 // for the given address
691 inline BitMap::idx_t card_bitmap_index_for(HeapWord* addr);
692
693 // Counts the size of the given memory region in the the given
694 // marked_bytes array slot for the given HeapRegion.
695 // Sets the bits in the given card bitmap that are associated with the
696 // cards that are spanned by the memory region.
697 inline void count_region(MemRegion mr,
698 HeapRegion* hr,
699 size_t* marked_bytes_array,
700 BitMap* task_card_bm);
701
702 // Counts the given object in the given task/worker counting
703 // data structures.
704 inline void count_object(oop obj,
705 HeapRegion* hr,
706 size_t* marked_bytes_array,
707 BitMap* task_card_bm,
708 size_t word_size);
709
710 // Attempts to mark the given object and, if successful, counts
711 // the object in the given task/worker counting structures.
712 inline bool par_mark_and_count(oop obj,
713 HeapRegion* hr,
714 size_t* marked_bytes_array,
715 BitMap* task_card_bm);
716
717 // Attempts to mark the given object and, if successful, counts
718 // the object in the task/worker counting structures for the
719 // given worker id.
720 inline bool par_mark_and_count(oop obj,
721 size_t word_size,
722 HeapRegion* hr,
723 uint worker_id);
724
725 // Returns true if initialization was successfully completed.
726 bool completed_initialization() const {
727 return _completed_initialization;
728 }
729
730 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; }
731 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; }
732
733 protected:
734 // Clear all the per-task bitmaps and arrays used to store the
735 // counting data.
736 void clear_all_count_data();
737
738 // Aggregates the counting data for each worker/task
739 // that was constructed while marking. Also sets
740 // the amount of marked bytes for each region and
741 // the top at concurrent mark count.
742 void aggregate_count_data();
743
744 // Verification routine
745 void verify_count_data();
746 };
747
748 // A class representing a marking task.
749 class G1CMTask : public TerminatorTerminator {
750 private:
751 enum PrivateConstants {
752 // the regular clock call is called once the scanned words reaches
753 // this limit
754 words_scanned_period = 12*1024,
755 // the regular clock call is called once the number of visited
756 // references reaches this limit
757 refs_reached_period = 384,
758 // initial value for the hash seed, used in the work stealing code
759 init_hash_seed = 17,
760 // how many entries will be transferred between global stack and
761 // local queues
762 global_stack_transfer_size = 16
763 };
764
765 uint _worker_id;
827 // dealing with them)
828 bool _draining_satb_buffers;
829
830 // number sequence of past step times
831 NumberSeq _step_times_ms;
832 // elapsed time of this task
833 double _elapsed_time_ms;
834 // termination time of this task
835 double _termination_time_ms;
836 // when this task got into the termination protocol
837 double _termination_start_time_ms;
838
839 // true when the task is during a concurrent phase, false when it is
840 // in the remark phase (so, in the latter case, we do not have to
841 // check all the things that we have to check during the concurrent
842 // phase, i.e. SATB buffer availability...)
843 bool _concurrent;
844
845 TruncatedSeq _marking_step_diffs_ms;
846
847 // Counting data structures. Embedding the task's marked_bytes_array
848 // and card bitmap into the actual task saves having to go through
849 // the ConcurrentMark object.
850 size_t* _marked_bytes_array;
851 BitMap* _card_bm;
852
853 // it updates the local fields after this task has claimed
854 // a new region to scan
855 void setup_for_region(HeapRegion* hr);
856 // it brings up-to-date the limit of the region
857 void update_region_limit();
858
859 // called when either the words scanned or the refs visited limit
860 // has been reached
861 void reached_limit();
862 // recalculates the words scanned and refs visited limits
863 void recalculate_limits();
864 // decreases the words scanned and refs visited limits when we reach
865 // an expensive operation
866 void decrease_limits();
867 // it checks whether the words scanned or refs visited reached their
868 // respective limit and calls reached_limit() if they have
869 void check_limits() {
870 if (_words_scanned >= _words_scanned_limit ||
871 _refs_reached >= _refs_reached_limit) {
872 reached_limit();
919 // Resets the local region fields after a task has finished scanning a
920 // region; or when they have become stale as a result of the region
921 // being evacuated.
922 void giveup_current_region();
923
924 HeapWord* finger() { return _finger; }
925
926 bool has_aborted() { return _has_aborted; }
927 void set_has_aborted() { _has_aborted = true; }
928 void clear_has_aborted() { _has_aborted = false; }
929 bool has_timed_out() { return _has_timed_out; }
930 bool claimed() { return _claimed; }
931
932 void set_cm_oop_closure(G1CMOopClosure* cm_oop_closure);
933
934 // Increment the number of references this task has visited.
935 void increment_refs_reached() { ++_refs_reached; }
936
937 // Grey the object by marking it. If not already marked, push it on
938 // the local queue if below the finger.
939 // Precondition: obj is in region.
940 // Precondition: obj is below region's NTAMS.
941 inline void make_reference_grey(oop obj, HeapRegion* region);
942
943 // Grey the object (by calling make_grey_reference) if required,
944 // e.g. obj is below its containing region's NTAMS.
945 // Precondition: obj is a valid heap object.
946 inline void deal_with_reference(oop obj);
947
948 // It scans an object and visits its children.
949 inline void scan_object(oop obj);
950
951 // It pushes an object on the local queue.
952 inline void push(oop obj);
953
954 // These two move entries to/from the global stack.
955 void move_entries_to_global_stack();
956 void get_entries_from_global_stack();
957
958 // It pops and scans objects from the local queue. If partially is
959 // true, then it stops when the queue size is of a given limit. If
960 // partially is false, then it stops when the queue is empty.
961 void drain_local_queue(bool partially);
962 // It moves entries from the global stack to the local queue and
963 // drains the local queue. If partially is true, then it stops when
964 // both the global stack and the local queue reach a given size. If
965 // partially if false, it tries to empty them totally.
966 void drain_global_stack(bool partially);
967 // It keeps picking SATB buffers and processing them until no SATB
968 // buffers are available.
969 void drain_satb_buffers();
970
971 // moves the local finger to a new location
972 inline void move_finger_to(HeapWord* new_finger) {
973 assert(new_finger >= _finger && new_finger < _region_limit, "invariant");
974 _finger = new_finger;
975 }
976
977 G1CMTask(uint worker_id,
978 G1ConcurrentMark *cm,
979 size_t* marked_bytes,
980 BitMap* card_bm,
981 G1CMTaskQueue* task_queue,
982 G1CMTaskQueueSet* task_queues);
983
984 // it prints statistics associated with this task
985 void print_stats();
986 };
987
988 // Class that's used to to print out per-region liveness
989 // information. It's currently used at the end of marking and also
990 // after we sort the old regions at the end of the cleanup operation.
991 class G1PrintRegionLivenessInfoClosure: public HeapRegionClosure {
992 private:
993 // Accumulators for these values.
994 size_t _total_used_bytes;
995 size_t _total_capacity_bytes;
996 size_t _total_prev_live_bytes;
997 size_t _total_next_live_bytes;
998
999 // Accumulator for the remembered set size
1000 size_t _total_remset_bytes;
|
249 // all have been claimed.
250 HeapRegion* claim_next();
251
252 void cancel_scan();
253
254 // Flag that we're done with root region scanning and notify anyone
255 // who's waiting on it. If aborted is false, assume that all regions
256 // have been claimed.
257 void scan_finished();
258
259 // If CM threads are still scanning root regions, wait until they
260 // are done. Return true if we had to wait, false otherwise.
261 bool wait_until_scan_finished();
262 };
263
264 class ConcurrentMarkThread;
265
266 class G1ConcurrentMark: public CHeapObj<mtGC> {
267 friend class ConcurrentMarkThread;
268 friend class G1ParNoteEndTask;
269 friend class G1VerifyLiveDataClosure;
270 friend class G1CMRefProcTaskProxy;
271 friend class G1CMRefProcTaskExecutor;
272 friend class G1CMKeepAliveAndDrainClosure;
273 friend class G1CMDrainMarkingStackClosure;
274 friend class G1CMBitMapClosure;
275 friend class G1CMConcurrentMarkingTask;
276 friend class G1CMMarkStack;
277 friend class G1CMRemarkTask;
278 friend class G1CMTask;
279
280 protected:
281 ConcurrentMarkThread* _cmThread; // The thread doing the work
282 G1CollectedHeap* _g1h; // The heap
283 uint _parallel_marking_threads; // The number of marking
284 // threads we're using
285 uint _max_parallel_marking_threads; // Max number of marking
286 // threads we'll ever use
287 double _sleep_factor; // How much we have to sleep, with
288 // respect to the work we just did, to
289 // meet the marking overhead goal
290 double _marking_task_overhead; // Marking target overhead for
291 // a single task
292
293 FreeRegionList _cleanup_list;
294
295 // Concurrent marking support structures
296 G1CMBitMap _markBitMap1;
297 G1CMBitMap _markBitMap2;
298 G1CMBitMapRO* _prevMarkBitMap; // Completed mark bitmap
299 G1CMBitMap* _nextMarkBitMap; // Under-construction mark bitmap
300
301 // Liveness count data. After marking G1 iterates over the recently gathered mark
302 // bitmap and records rough information about liveness on card and region basis.
303 // This information can be used for e.g. remembered set scrubbing.
304
305 // A set bit indicates whether the given region contains any live object.
306 BitMap _region_live_bm;
307 // A set bit indicates that the given card contains a live object.
308 BitMap _card_live_bm;
309
310 // Heap bounds
311 HeapWord* _heap_start;
312 HeapWord* _heap_end;
313
314 // Root region tracking and claiming
315 G1CMRootRegions _root_regions;
316
317 // For gray objects
318 G1CMMarkStack _markStack; // Grey objects behind global finger
319 HeapWord* volatile _finger; // The global finger, region aligned,
320 // always points to the end of the
321 // last claimed region
322
323 // Marking tasks
324 uint _max_worker_id;// Maximum worker id
325 uint _active_tasks; // Task num currently active
326 G1CMTask** _tasks; // Task queue array (max_worker_id len)
327 G1CMTaskQueueSet* _task_queues; // Task queue set
328 ParallelTaskTerminator _terminator; // For termination
362 G1OldTracer* _gc_tracer_cm;
363
364 // All of these times are in ms
365 NumberSeq _init_times;
366 NumberSeq _remark_times;
367 NumberSeq _remark_mark_times;
368 NumberSeq _remark_weak_ref_times;
369 NumberSeq _cleanup_times;
370 double _total_counting_time;
371 double _total_rs_scrub_time;
372
373 double* _accum_task_vtime; // Accumulated task vtime
374
375 WorkGang* _parallel_workers;
376
377 void weakRefsWorkParallelPart(BoolObjectClosure* is_alive, bool purged_classes);
378 void weakRefsWork(bool clear_all_soft_refs);
379
380 void swapMarkBitMaps();
381
382 // Allocates and returns a zero-ed out "large" bitmap of the given size in bits.
383 // It is always allocated using virtual memory.
384 BitMap allocate_large_bitmap(BitMap::idx_t size_in_bits);
385 // Allocates the memory for all bitmaps used by the concurrent marking.
386 void allocate_internal_bitmaps();
387 // Pre-touches the internal bitmaps.
388 void pretouch_internal_bitmaps();
389
390 // It resets the global marking data structures, as well as the
391 // task local ones; should be called during initial mark.
392 void reset();
393
394 // Resets all the marking data structures. Called when we have to restart
395 // marking or when marking completes (via set_non_marking_state below).
396 void reset_marking_state(bool clear_overflow = true);
397
398 // We do this after we're done with marking so that the marking data
399 // structures are initialized to a sensible and predictable state.
400 void set_non_marking_state();
401
402 // Called to indicate how many threads are currently active.
403 void set_concurrency(uint active_tasks);
404
405 // It should be called to indicate which phase we're in (concurrent
406 // mark or remark) and how many threads are currently active.
407 void set_concurrency_and_phase(uint active_tasks, bool concurrent);
408
409 // Prints all gathered CM-related statistics
458 G1CMTaskQueue* task_queue(int id) {
459 assert(0 <= id && id < (int) _active_tasks,
460 "task queue id not within active bounds");
461 return (G1CMTaskQueue*) _task_queues->queue(id);
462 }
463
464 // Returns the task queue set
465 G1CMTaskQueueSet* task_queues() { return _task_queues; }
466
467 // Access / manipulation of the overflow flag which is set to
468 // indicate that the global stack has overflown
469 bool has_overflown() { return _has_overflown; }
470 void set_has_overflown() { _has_overflown = true; }
471 void clear_has_overflown() { _has_overflown = false; }
472 bool restart_for_overflow() { return _restart_for_overflow; }
473
474 // Methods to enter the two overflow sync barriers
475 void enter_first_sync_barrier(uint worker_id);
476 void enter_second_sync_barrier(uint worker_id);
477
478 // Card index of the bottom of the G1 heap. Used for biasing indices into
479 // the card bitmaps.
480 intptr_t _heap_bottom_card_num;
481
482 // Set to true when initialization is complete
483 bool _completed_initialization;
484
485 // end_timer, true to end gc timer after ending concurrent phase.
486 void register_concurrent_phase_end_common(bool end_timer);
487
488 // Clear the given bitmap in parallel using the given WorkGang. If may_yield is
489 // true, periodically insert checks to see if this method should exit prematurely.
490 void clear_bitmap(G1CMBitMap* bitmap, WorkGang* workers, bool may_yield);
491 public:
492 // Manipulation of the global mark stack.
493 // The push and pop operations are used by tasks for transfers
494 // between task-local queues and the global mark stack, and use
495 // locking for concurrency safety.
496 bool mark_stack_push(oop* arr, int n) {
497 _markStack.par_push_arr(arr, n);
543 G1RegionToSpaceMapper* next_bitmap_storage);
544 ~G1ConcurrentMark();
545
546 ConcurrentMarkThread* cmThread() { return _cmThread; }
547
548 G1CMBitMapRO* prevMarkBitMap() const { return _prevMarkBitMap; }
549 G1CMBitMap* nextMarkBitMap() const { return _nextMarkBitMap; }
550
551 // Returns the number of GC threads to be used in a concurrent
552 // phase based on the number of GC threads being used in a STW
553 // phase.
554 uint scale_parallel_threads(uint n_par_threads);
555
556 // Calculates the number of GC threads to be used in a concurrent phase.
557 uint calc_parallel_marking_threads();
558
559 // The following three are interaction between CM and
560 // G1CollectedHeap
561
562 // This notifies CM that a root during initial-mark needs to be
563 // grayed. It is MT-safe. hr is the region that
564 // contains the object and it's passed optionally from callers who
565 // might already have it (no point in recalculating it).
566 inline void grayRoot(oop obj,
567 HeapRegion* hr = NULL);
568
569 // Prepare internal data structures for the next mark cycle. This includes clearing
570 // the next mark bitmap and some internal data structures. This method is intended
571 // to be called concurrently to the mutator. It will yield to safepoint requests.
572 void cleanup_for_next_mark();
573
574 // Clear the previous marking bitmap during safepoint.
575 void clear_prev_bitmap(WorkGang* workers);
576
577 // Return whether the next mark bitmap has no marks set. To be used for assertions
578 // only. Will not yield to pause requests.
579 bool nextMarkBitmapIsClear();
580
581 // These two do the work that needs to be done before and after the
582 // initial root checkpoint. Since this checkpoint can be done at two
583 // different points (i.e. an explicit pause or piggy-backed on a
584 // young collection), then it's nice to be able to easily share the
585 // pre/post code. It might be the case that we can put everything in
586 // the post method. TP
613
614 // Notify data structures that a GC has started.
615 void note_start_of_gc() {
616 _markStack.note_start_of_gc();
617 }
618
619 // Notify data structures that a GC is finished.
620 void note_end_of_gc() {
621 _markStack.note_end_of_gc();
622 }
623
624 // Verify that there are no CSet oops on the stacks (taskqueues /
625 // global mark stack) and fingers (global / per-task).
626 // If marking is not in progress, it's a no-op.
627 void verify_no_cset_oops() PRODUCT_RETURN;
628
629 inline bool isPrevMarked(oop p) const;
630
631 inline bool do_yield_check(uint worker_i = 0);
632
633 // Abandon current marking iteration due to a Full GC.
634 void abort();
635
636 bool has_aborted() { return _has_aborted; }
637
638 void print_summary_info();
639
640 void print_worker_threads_on(outputStream* st) const;
641
642 void print_on_error(outputStream* st) const;
643
644 // Attempts to mark the given object on the next mark bitmap.
645 inline bool par_mark(oop obj);
646
647 // Returns true if initialization was successfully completed.
648 bool completed_initialization() const {
649 return _completed_initialization;
650 }
651
652 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; }
653 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; }
654
655 private:
656 // Clear (Reset) all liveness count data.
657 void clear_all_live_data(WorkGang* workers);
658
659 // Verify all of the above data structures that they are in initial state.
660 void verify_all_live_data();
661
662 // Aggregates the per-card liveness data based on the current marking. Also sets
663 // the amount of marked bytes for each region.
664 void create_live_data();
665
666 // Verification routine
667 void verify_live_data();
668 };
669
670 // A class representing a marking task.
671 class G1CMTask : public TerminatorTerminator {
672 private:
673 enum PrivateConstants {
674 // the regular clock call is called once the scanned words reaches
675 // this limit
676 words_scanned_period = 12*1024,
677 // the regular clock call is called once the number of visited
678 // references reaches this limit
679 refs_reached_period = 384,
680 // initial value for the hash seed, used in the work stealing code
681 init_hash_seed = 17,
682 // how many entries will be transferred between global stack and
683 // local queues
684 global_stack_transfer_size = 16
685 };
686
687 uint _worker_id;
749 // dealing with them)
750 bool _draining_satb_buffers;
751
752 // number sequence of past step times
753 NumberSeq _step_times_ms;
754 // elapsed time of this task
755 double _elapsed_time_ms;
756 // termination time of this task
757 double _termination_time_ms;
758 // when this task got into the termination protocol
759 double _termination_start_time_ms;
760
761 // true when the task is during a concurrent phase, false when it is
762 // in the remark phase (so, in the latter case, we do not have to
763 // check all the things that we have to check during the concurrent
764 // phase, i.e. SATB buffer availability...)
765 bool _concurrent;
766
767 TruncatedSeq _marking_step_diffs_ms;
768
769 // it updates the local fields after this task has claimed
770 // a new region to scan
771 void setup_for_region(HeapRegion* hr);
772 // it brings up-to-date the limit of the region
773 void update_region_limit();
774
775 // called when either the words scanned or the refs visited limit
776 // has been reached
777 void reached_limit();
778 // recalculates the words scanned and refs visited limits
779 void recalculate_limits();
780 // decreases the words scanned and refs visited limits when we reach
781 // an expensive operation
782 void decrease_limits();
783 // it checks whether the words scanned or refs visited reached their
784 // respective limit and calls reached_limit() if they have
785 void check_limits() {
786 if (_words_scanned >= _words_scanned_limit ||
787 _refs_reached >= _refs_reached_limit) {
788 reached_limit();
835 // Resets the local region fields after a task has finished scanning a
836 // region; or when they have become stale as a result of the region
837 // being evacuated.
838 void giveup_current_region();
839
840 HeapWord* finger() { return _finger; }
841
842 bool has_aborted() { return _has_aborted; }
843 void set_has_aborted() { _has_aborted = true; }
844 void clear_has_aborted() { _has_aborted = false; }
845 bool has_timed_out() { return _has_timed_out; }
846 bool claimed() { return _claimed; }
847
848 void set_cm_oop_closure(G1CMOopClosure* cm_oop_closure);
849
850 // Increment the number of references this task has visited.
851 void increment_refs_reached() { ++_refs_reached; }
852
853 // Grey the object by marking it. If not already marked, push it on
854 // the local queue if below the finger.
855 // Precondition: obj is below region's NTAMS.
856 inline void make_reference_grey(oop obj);
857
858 // Grey the object (by calling make_grey_reference) if required,
859 // e.g. obj is below its containing region's NTAMS.
860 // Precondition: obj is a valid heap object.
861 inline void deal_with_reference(oop obj);
862
863 // It scans an object and visits its children.
864 inline void scan_object(oop obj);
865
866 // It pushes an object on the local queue.
867 inline void push(oop obj);
868
869 // These two move entries to/from the global stack.
870 void move_entries_to_global_stack();
871 void get_entries_from_global_stack();
872
873 // It pops and scans objects from the local queue. If partially is
874 // true, then it stops when the queue size is of a given limit. If
875 // partially is false, then it stops when the queue is empty.
876 void drain_local_queue(bool partially);
877 // It moves entries from the global stack to the local queue and
878 // drains the local queue. If partially is true, then it stops when
879 // both the global stack and the local queue reach a given size. If
880 // partially if false, it tries to empty them totally.
881 void drain_global_stack(bool partially);
882 // It keeps picking SATB buffers and processing them until no SATB
883 // buffers are available.
884 void drain_satb_buffers();
885
886 // moves the local finger to a new location
887 inline void move_finger_to(HeapWord* new_finger) {
888 assert(new_finger >= _finger && new_finger < _region_limit, "invariant");
889 _finger = new_finger;
890 }
891
892 G1CMTask(uint worker_id,
893 G1ConcurrentMark *cm,
894 G1CMTaskQueue* task_queue,
895 G1CMTaskQueueSet* task_queues);
896
897 // it prints statistics associated with this task
898 void print_stats();
899 };
900
901 // Class that's used to to print out per-region liveness
902 // information. It's currently used at the end of marking and also
903 // after we sort the old regions at the end of the cleanup operation.
904 class G1PrintRegionLivenessInfoClosure: public HeapRegionClosure {
905 private:
906 // Accumulators for these values.
907 size_t _total_used_bytes;
908 size_t _total_capacity_bytes;
909 size_t _total_prev_live_bytes;
910 size_t _total_next_live_bytes;
911
912 // Accumulator for the remembered set size
913 size_t _total_remset_bytes;
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