1 /*
2 * Copyright (c) 2001, 2016, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #ifndef SHARE_VM_GC_G1_G1CONCURRENTMARK_HPP
26 #define SHARE_VM_GC_G1_G1CONCURRENTMARK_HPP
27
28 #include "classfile/javaClasses.hpp"
29 #include "gc/g1/g1RegionToSpaceMapper.hpp"
30 #include "gc/g1/heapRegionSet.hpp"
31 #include "gc/shared/taskqueue.hpp"
32
33 class G1CollectedHeap;
34 class G1CMBitMap;
35 class G1CMTask;
36 class G1ConcurrentMark;
37 class ConcurrentGCTimer;
38 class G1OldTracer;
39 typedef GenericTaskQueue<oop, mtGC> G1CMTaskQueue;
40 typedef GenericTaskQueueSet<G1CMTaskQueue, mtGC> G1CMTaskQueueSet;
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 // A generic CM bit map. This is essentially a wrapper around the BitMap
57 // class, with one bit per (1<<_shifter) HeapWords.
58
59 class G1CMBitMapRO VALUE_OBJ_CLASS_SPEC {
60 protected:
61 HeapWord* _bmStartWord; // base address of range covered by map
62 size_t _bmWordSize; // map size (in #HeapWords covered)
63 const int _shifter; // map to char or bit
64 BitMap _bm; // the bit map itself
65
66 public:
67 // constructor
68 G1CMBitMapRO(int shifter);
69
70 // inquiries
71 HeapWord* startWord() const { return _bmStartWord; }
72 // the following is one past the last word in space
73 HeapWord* endWord() const { return _bmStartWord + _bmWordSize; }
74
75 // read marks
76
77 bool isMarked(HeapWord* addr) const {
78 assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),
79 "outside underlying space?");
80 return _bm.at(heapWordToOffset(addr));
81 }
82
83 // iteration
84 inline bool iterate(BitMapClosure* cl, MemRegion mr);
85
86 // Return the address corresponding to the next marked bit at or after
87 // "addr", and before "limit", if "limit" is non-NULL. If there is no
88 // such bit, returns "limit" if that is non-NULL, or else "endWord()".
89 HeapWord* getNextMarkedWordAddress(const HeapWord* addr,
90 const HeapWord* limit = NULL) const;
91
92 // conversion utilities
93 HeapWord* offsetToHeapWord(size_t offset) const {
94 return _bmStartWord + (offset << _shifter);
95 }
96 size_t heapWordToOffset(const HeapWord* addr) const {
97 return pointer_delta(addr, _bmStartWord) >> _shifter;
98 }
99
100 // The argument addr should be the start address of a valid object
101 inline HeapWord* nextObject(HeapWord* addr);
102
103 void print_on_error(outputStream* st, const char* prefix) const;
104
105 // debugging
106 NOT_PRODUCT(bool covers(MemRegion rs) const;)
107 };
108
109 class G1CMBitMapMappingChangedListener : public G1MappingChangedListener {
110 private:
111 G1CMBitMap* _bm;
112 public:
113 G1CMBitMapMappingChangedListener() : _bm(NULL) {}
114
115 void set_bitmap(G1CMBitMap* bm) { _bm = bm; }
116
117 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
118 };
119
120 class G1CMBitMap : public G1CMBitMapRO {
121 private:
122 G1CMBitMapMappingChangedListener _listener;
123
124 public:
125 static size_t compute_size(size_t heap_size);
126 // Returns the amount of bytes on the heap between two marks in the bitmap.
127 static size_t mark_distance();
128 // Returns how many bytes (or bits) of the heap a single byte (or bit) of the
129 // mark bitmap corresponds to. This is the same as the mark distance above.
130 static size_t heap_map_factor() {
131 return mark_distance();
132 }
133
134 G1CMBitMap() : G1CMBitMapRO(LogMinObjAlignment), _listener() { _listener.set_bitmap(this); }
135
136 // Initializes the underlying BitMap to cover the given area.
137 void initialize(MemRegion heap, G1RegionToSpaceMapper* storage);
138
139 // Write marks.
140 inline void mark(HeapWord* addr);
141 inline void clear(HeapWord* addr);
142 inline bool parMark(HeapWord* addr);
143
144 void clear_range(MemRegion mr);
145 };
146
147 // Represents a marking stack used by ConcurrentMarking in the G1 collector.
148 class G1CMMarkStack VALUE_OBJ_CLASS_SPEC {
149 VirtualSpace _virtual_space; // Underlying backing store for actual stack
150 G1ConcurrentMark* _cm;
151 oop* _base; // bottom of stack
152 jint _index; // one more than last occupied index
153 jint _capacity; // max #elements
154 jint _saved_index; // value of _index saved at start of GC
155
156 bool _overflow;
157 bool _should_expand;
158
159 public:
160 G1CMMarkStack(G1ConcurrentMark* cm);
161 ~G1CMMarkStack();
162
163 bool allocate(size_t capacity);
164
165 // Pushes the first "n" elements of "ptr_arr" on the stack.
166 // Locking impl: concurrency is allowed only with
167 // "par_push_arr" and/or "par_pop_arr" operations, which use the same
168 // locking strategy.
169 void par_push_arr(oop* ptr_arr, int n);
170
171 // If returns false, the array was empty. Otherwise, removes up to "max"
172 // elements from the stack, and transfers them to "ptr_arr" in an
173 // unspecified order. The actual number transferred is given in "n" ("n
174 // == 0" is deliberately redundant with the return value.) Locking impl:
175 // concurrency is allowed only with "par_push_arr" and/or "par_pop_arr"
176 // operations, which use the same locking strategy.
177 bool par_pop_arr(oop* ptr_arr, int max, int* n);
178
179 bool isEmpty() { return _index == 0; }
180 int maxElems() { return _capacity; }
181
182 bool overflow() { return _overflow; }
183 void clear_overflow() { _overflow = false; }
184
185 bool should_expand() const { return _should_expand; }
186 void set_should_expand();
187
188 // Expand the stack, typically in response to an overflow condition
189 void expand();
190
191 int size() { return _index; }
192
193 void setEmpty() { _index = 0; clear_overflow(); }
194
195 // Record the current index.
196 void note_start_of_gc();
197
198 // Make sure that we have not added any entries to the stack during GC.
199 void note_end_of_gc();
200
201 // Apply fn to each oop in the mark stack, up to the bound recorded
202 // via one of the above "note" functions. The mark stack must not
203 // be modified while iterating.
204 template<typename Fn> void iterate(Fn fn);
205 };
206
207 class YoungList;
208
209 // Root Regions are regions that are not empty at the beginning of a
210 // marking cycle and which we might collect during an evacuation pause
211 // while the cycle is active. Given that, during evacuation pauses, we
212 // do not copy objects that are explicitly marked, what we have to do
213 // for the root regions is to scan them and mark all objects reachable
214 // from them. According to the SATB assumptions, we only need to visit
215 // each object once during marking. So, as long as we finish this scan
216 // before the next evacuation pause, we can copy the objects from the
217 // root regions without having to mark them or do anything else to them.
218 //
219 // Currently, we only support root region scanning once (at the start
220 // of the marking cycle) and the root regions are all the survivor
221 // regions populated during the initial-mark pause.
222 class G1CMRootRegions VALUE_OBJ_CLASS_SPEC {
223 private:
224 YoungList* _young_list;
225 G1ConcurrentMark* _cm;
226
227 volatile bool _scan_in_progress;
228 volatile bool _should_abort;
229 HeapRegion* volatile _next_survivor;
230
231 void notify_scan_done();
232
233 public:
234 G1CMRootRegions();
235 // We actually do most of the initialization in this method.
236 void init(G1CollectedHeap* g1h, G1ConcurrentMark* cm);
237
238 // Reset the claiming / scanning of the root regions.
239 void prepare_for_scan();
240
241 // Forces get_next() to return NULL so that the iteration aborts early.
242 void abort() { _should_abort = true; }
243
244 // Return true if the CM thread are actively scanning root regions,
245 // false otherwise.
246 bool scan_in_progress() { return _scan_in_progress; }
247
248 // Claim the next root region to scan atomically, or return NULL if
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
329
330 // Two sync barriers that are used to synchronize tasks when an
331 // overflow occurs. The algorithm is the following. All tasks enter
332 // the first one to ensure that they have all stopped manipulating
333 // the global data structures. After they exit it, they re-initialize
334 // their data structures and task 0 re-initializes the global data
335 // structures. Then, they enter the second sync barrier. This
336 // ensure, that no task starts doing work before all data
337 // structures (local and global) have been re-initialized. When they
338 // exit it, they are free to start working again.
339 WorkGangBarrierSync _first_overflow_barrier_sync;
340 WorkGangBarrierSync _second_overflow_barrier_sync;
341
342 // This is set by any task, when an overflow on the global data
343 // structures is detected
344 volatile bool _has_overflown;
345 // True: marking is concurrent, false: we're in remark
346 volatile bool _concurrent;
347 // Set at the end of a Full GC so that marking aborts
348 volatile bool _has_aborted;
349
350 // Used when remark aborts due to an overflow to indicate that
351 // another concurrent marking phase should start
352 volatile bool _restart_for_overflow;
353
354 // This is true from the very start of concurrent marking until the
355 // point when all the tasks complete their work. It is really used
356 // to determine the points between the end of concurrent marking and
357 // time of remark.
358 volatile bool _concurrent_marking_in_progress;
359
360 ConcurrentGCTimer* _gc_timer_cm;
361
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
410 void print_stats();
411
412 bool cleanup_list_is_empty() {
413 return _cleanup_list.is_empty();
414 }
415
416 // Accessor methods
417 uint parallel_marking_threads() const { return _parallel_marking_threads; }
418 uint max_parallel_marking_threads() const { return _max_parallel_marking_threads;}
419 double sleep_factor() { return _sleep_factor; }
420 double marking_task_overhead() { return _marking_task_overhead;}
421
422 HeapWord* finger() { return _finger; }
423 bool concurrent() { return _concurrent; }
424 uint active_tasks() { return _active_tasks; }
425 ParallelTaskTerminator* terminator() { return &_terminator; }
426
427 // It claims the next available region to be scanned by a marking
428 // task/thread. It might return NULL if the next region is empty or
429 // we have run out of regions. In the latter case, out_of_regions()
430 // determines whether we've really run out of regions or the task
431 // should call claim_region() again. This might seem a bit
432 // awkward. Originally, the code was written so that claim_region()
433 // either successfully returned with a non-empty region or there
434 // were no more regions to be claimed. The problem with this was
435 // that, in certain circumstances, it iterated over large chunks of
436 // the heap finding only empty regions and, while it was working, it
437 // was preventing the calling task to call its regular clock
438 // method. So, this way, each task will spend very little time in
439 // claim_region() and is allowed to call the regular clock method
440 // frequently.
441 HeapRegion* claim_region(uint worker_id);
442
443 // It determines whether we've run out of regions to scan. Note that
444 // the finger can point past the heap end in case the heap was expanded
445 // to satisfy an allocation without doing a GC. This is fine, because all
446 // objects in those regions will be considered live anyway because of
447 // SATB guarantees (i.e. their TAMS will be equal to bottom).
448 bool out_of_regions() { return _finger >= _heap_end; }
449
450 // Returns the task with the given id
451 G1CMTask* task(int id) {
452 assert(0 <= id && id < (int) _active_tasks,
453 "task id not within active bounds");
454 return _tasks[id];
455 }
456
457 // Returns the task queue with the given id
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);
498 if (_markStack.overflow()) {
499 set_has_overflown();
500 return false;
501 }
502 return true;
503 }
504 void mark_stack_pop(oop* arr, int max, int* n) {
505 _markStack.par_pop_arr(arr, max, n);
506 }
507 size_t mark_stack_size() { return _markStack.size(); }
508 size_t partial_mark_stack_size_target() { return _markStack.maxElems()/3; }
509 bool mark_stack_overflow() { return _markStack.overflow(); }
510 bool mark_stack_empty() { return _markStack.isEmpty(); }
511
512 G1CMRootRegions* root_regions() { return &_root_regions; }
513
514 bool concurrent_marking_in_progress() {
515 return _concurrent_marking_in_progress;
516 }
517 void set_concurrent_marking_in_progress() {
518 _concurrent_marking_in_progress = true;
519 }
520 void clear_concurrent_marking_in_progress() {
521 _concurrent_marking_in_progress = false;
522 }
523
524 void concurrent_cycle_start();
525 void concurrent_cycle_end();
526
527 void update_accum_task_vtime(int i, double vtime) {
528 _accum_task_vtime[i] += vtime;
529 }
530
531 double all_task_accum_vtime() {
532 double ret = 0.0;
533 for (uint i = 0; i < _max_worker_id; ++i)
534 ret += _accum_task_vtime[i];
535 return ret;
536 }
537
538 // Attempts to steal an object from the task queues of other tasks
539 bool try_stealing(uint worker_id, int* hash_seed, oop& obj);
540
541 G1ConcurrentMark(G1CollectedHeap* g1h,
542 G1RegionToSpaceMapper* prev_bitmap_storage,
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
587 void checkpointRootsInitialPre();
588 void checkpointRootsInitialPost();
589
590 // Scan all the root regions and mark everything reachable from
591 // them.
592 void scan_root_regions();
593
594 // Scan a single root region and mark everything reachable from it.
595 void scanRootRegion(HeapRegion* hr, uint worker_id);
596
597 // Do concurrent phase of marking, to a tentative transitive closure.
598 void mark_from_roots();
599
600 void checkpointRootsFinal(bool clear_all_soft_refs);
601 void checkpointRootsFinalWork();
602 void cleanup();
603 void complete_cleanup();
604
605 // Mark in the previous bitmap. NB: this is usually read-only, so use
606 // this carefully!
607 inline void markPrev(oop p);
608
609 // Clears marks for all objects in the given range, for the prev or
610 // next bitmaps. NB: the previous bitmap is usually
611 // read-only, so use this carefully!
612 void clearRangePrevBitmap(MemRegion mr);
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;
688 G1CollectedHeap* _g1h;
689 G1ConcurrentMark* _cm;
690 G1CMBitMap* _nextMarkBitMap;
691 // the task queue of this task
692 G1CMTaskQueue* _task_queue;
693 private:
694 // the task queue set---needed for stealing
695 G1CMTaskQueueSet* _task_queues;
696 // indicates whether the task has been claimed---this is only for
697 // debugging purposes
698 bool _claimed;
699
700 // number of calls to this task
701 int _calls;
702
703 // when the virtual timer reaches this time, the marking step should
704 // exit
705 double _time_target_ms;
706 // the start time of the current marking step
707 double _start_time_ms;
708
709 // the oop closure used for iterations over oops
710 G1CMOopClosure* _cm_oop_closure;
711
712 // the region this task is scanning, NULL if we're not scanning any
713 HeapRegion* _curr_region;
714 // the local finger of this task, NULL if we're not scanning a region
715 HeapWord* _finger;
716 // limit of the region this task is scanning, NULL if we're not scanning one
717 HeapWord* _region_limit;
718
719 // the number of words this task has scanned
720 size_t _words_scanned;
721 // When _words_scanned reaches this limit, the regular clock is
722 // called. Notice that this might be decreased under certain
723 // circumstances (i.e. when we believe that we did an expensive
724 // operation).
725 size_t _words_scanned_limit;
726 // the initial value of _words_scanned_limit (i.e. what it was
727 // before it was decreased).
728 size_t _real_words_scanned_limit;
729
730 // the number of references this task has visited
731 size_t _refs_reached;
732 // When _refs_reached reaches this limit, the regular clock is
733 // called. Notice this this might be decreased under certain
734 // circumstances (i.e. when we believe that we did an expensive
735 // operation).
736 size_t _refs_reached_limit;
737 // the initial value of _refs_reached_limit (i.e. what it was before
738 // it was decreased).
739 size_t _real_refs_reached_limit;
740
741 // used by the work stealing stuff
742 int _hash_seed;
743 // if this is true, then the task has aborted for some reason
744 bool _has_aborted;
745 // set when the task aborts because it has met its time quota
746 bool _has_timed_out;
747 // true when we're draining SATB buffers; this avoids the task
748 // aborting due to SATB buffers being available (as we're already
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();
789 }
790 }
791 // this is supposed to be called regularly during a marking step as
792 // it checks a bunch of conditions that might cause the marking step
793 // to abort
794 void regular_clock_call();
795 bool concurrent() { return _concurrent; }
796
797 // Test whether obj might have already been passed over by the
798 // mark bitmap scan, and so needs to be pushed onto the mark stack.
799 bool is_below_finger(oop obj, HeapWord* global_finger) const;
800
801 template<bool scan> void process_grey_object(oop obj);
802
803 public:
804 // It resets the task; it should be called right at the beginning of
805 // a marking phase.
806 void reset(G1CMBitMap* _nextMarkBitMap);
807 // it clears all the fields that correspond to a claimed region.
808 void clear_region_fields();
809
810 void set_concurrent(bool concurrent) { _concurrent = concurrent; }
811
812 // The main method of this class which performs a marking step
813 // trying not to exceed the given duration. However, it might exit
814 // prematurely, according to some conditions (i.e. SATB buffers are
815 // available for processing).
816 void do_marking_step(double target_ms,
817 bool do_termination,
818 bool is_serial);
819
820 // These two calls start and stop the timer
821 void record_start_time() {
822 _elapsed_time_ms = os::elapsedTime() * 1000.0;
823 }
824 void record_end_time() {
825 _elapsed_time_ms = os::elapsedTime() * 1000.0 - _elapsed_time_ms;
826 }
827
828 // returns the worker ID associated with this task.
829 uint worker_id() { return _worker_id; }
830
831 // From TerminatorTerminator. It determines whether this task should
832 // exit the termination protocol after it's entered it.
833 virtual bool should_exit_termination();
834
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;
914
915 // Accumulator for strong code roots memory size
916 size_t _total_strong_code_roots_bytes;
917
918 static double perc(size_t val, size_t total) {
919 if (total == 0) {
920 return 0.0;
921 } else {
922 return 100.0 * ((double) val / (double) total);
923 }
924 }
925
926 static double bytes_to_mb(size_t val) {
927 return (double) val / (double) M;
928 }
929
930 public:
931 // The header and footer are printed in the constructor and
932 // destructor respectively.
933 G1PrintRegionLivenessInfoClosure(const char* phase_name);
934 virtual bool doHeapRegion(HeapRegion* r);
935 ~G1PrintRegionLivenessInfoClosure();
936 };
937
938 #endif // SHARE_VM_GC_G1_G1CONCURRENTMARK_HPP