Thu, 19 Jun 2014 13:31:14 +0200
8043607: Add a GC id as a log decoration similar to PrintGCTimeStamps
Reviewed-by: jwilhelm, ehelin, tschatzl
1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTMARK_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTMARK_HPP
28 #include "gc_implementation/g1/heapRegionSet.hpp"
29 #include "gc_implementation/shared/gcId.hpp"
30 #include "utilities/taskqueue.hpp"
32 class G1CollectedHeap;
33 class CMTask;
34 typedef GenericTaskQueue<oop, mtGC> CMTaskQueue;
35 typedef GenericTaskQueueSet<CMTaskQueue, mtGC> CMTaskQueueSet;
37 // Closure used by CM during concurrent reference discovery
38 // and reference processing (during remarking) to determine
39 // if a particular object is alive. It is primarily used
40 // to determine if referents of discovered reference objects
41 // are alive. An instance is also embedded into the
42 // reference processor as the _is_alive_non_header field
43 class G1CMIsAliveClosure: public BoolObjectClosure {
44 G1CollectedHeap* _g1;
45 public:
46 G1CMIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) { }
48 bool do_object_b(oop obj);
49 };
51 // A generic CM bit map. This is essentially a wrapper around the BitMap
52 // class, with one bit per (1<<_shifter) HeapWords.
54 class CMBitMapRO VALUE_OBJ_CLASS_SPEC {
55 protected:
56 HeapWord* _bmStartWord; // base address of range covered by map
57 size_t _bmWordSize; // map size (in #HeapWords covered)
58 const int _shifter; // map to char or bit
59 VirtualSpace _virtual_space; // underlying the bit map
60 BitMap _bm; // the bit map itself
62 public:
63 // constructor
64 CMBitMapRO(int shifter);
66 enum { do_yield = true };
68 // inquiries
69 HeapWord* startWord() const { return _bmStartWord; }
70 size_t sizeInWords() const { return _bmWordSize; }
71 // the following is one past the last word in space
72 HeapWord* endWord() const { return _bmStartWord + _bmWordSize; }
74 // read marks
76 bool isMarked(HeapWord* addr) const {
77 assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),
78 "outside underlying space?");
79 return _bm.at(heapWordToOffset(addr));
80 }
82 // iteration
83 inline bool iterate(BitMapClosure* cl, MemRegion mr);
84 inline bool iterate(BitMapClosure* cl);
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(HeapWord* addr,
90 HeapWord* limit = NULL) const;
91 // Return the address corresponding to the next unmarked bit at or after
92 // "addr", and before "limit", if "limit" is non-NULL. If there is no
93 // such bit, returns "limit" if that is non-NULL, or else "endWord()".
94 HeapWord* getNextUnmarkedWordAddress(HeapWord* addr,
95 HeapWord* limit = NULL) const;
97 // conversion utilities
98 HeapWord* offsetToHeapWord(size_t offset) const {
99 return _bmStartWord + (offset << _shifter);
100 }
101 size_t heapWordToOffset(HeapWord* addr) const {
102 return pointer_delta(addr, _bmStartWord) >> _shifter;
103 }
104 int heapWordDiffToOffsetDiff(size_t diff) const;
106 // The argument addr should be the start address of a valid object
107 HeapWord* nextObject(HeapWord* addr) {
108 oop obj = (oop) addr;
109 HeapWord* res = addr + obj->size();
110 assert(offsetToHeapWord(heapWordToOffset(res)) == res, "sanity");
111 return res;
112 }
114 void print_on_error(outputStream* st, const char* prefix) const;
116 // debugging
117 NOT_PRODUCT(bool covers(ReservedSpace rs) const;)
118 };
120 class CMBitMap : public CMBitMapRO {
122 public:
123 // constructor
124 CMBitMap(int shifter) :
125 CMBitMapRO(shifter) {}
127 // Allocates the back store for the marking bitmap
128 bool allocate(ReservedSpace heap_rs);
130 // write marks
131 void mark(HeapWord* addr) {
132 assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),
133 "outside underlying space?");
134 _bm.set_bit(heapWordToOffset(addr));
135 }
136 void clear(HeapWord* addr) {
137 assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),
138 "outside underlying space?");
139 _bm.clear_bit(heapWordToOffset(addr));
140 }
141 bool parMark(HeapWord* addr) {
142 assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),
143 "outside underlying space?");
144 return _bm.par_set_bit(heapWordToOffset(addr));
145 }
146 bool parClear(HeapWord* addr) {
147 assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),
148 "outside underlying space?");
149 return _bm.par_clear_bit(heapWordToOffset(addr));
150 }
151 void markRange(MemRegion mr);
152 void clearAll();
153 void clearRange(MemRegion mr);
155 // Starting at the bit corresponding to "addr" (inclusive), find the next
156 // "1" bit, if any. This bit starts some run of consecutive "1"'s; find
157 // the end of this run (stopping at "end_addr"). Return the MemRegion
158 // covering from the start of the region corresponding to the first bit
159 // of the run to the end of the region corresponding to the last bit of
160 // the run. If there is no "1" bit at or after "addr", return an empty
161 // MemRegion.
162 MemRegion getAndClearMarkedRegion(HeapWord* addr, HeapWord* end_addr);
163 };
165 // Represents a marking stack used by ConcurrentMarking in the G1 collector.
166 class CMMarkStack VALUE_OBJ_CLASS_SPEC {
167 VirtualSpace _virtual_space; // Underlying backing store for actual stack
168 ConcurrentMark* _cm;
169 oop* _base; // bottom of stack
170 jint _index; // one more than last occupied index
171 jint _capacity; // max #elements
172 jint _saved_index; // value of _index saved at start of GC
173 NOT_PRODUCT(jint _max_depth;) // max depth plumbed during run
175 bool _overflow;
176 bool _should_expand;
177 DEBUG_ONLY(bool _drain_in_progress;)
178 DEBUG_ONLY(bool _drain_in_progress_yields;)
180 public:
181 CMMarkStack(ConcurrentMark* cm);
182 ~CMMarkStack();
184 #ifndef PRODUCT
185 jint max_depth() const {
186 return _max_depth;
187 }
188 #endif
190 bool allocate(size_t capacity);
192 oop pop() {
193 if (!isEmpty()) {
194 return _base[--_index] ;
195 }
196 return NULL;
197 }
199 // If overflow happens, don't do the push, and record the overflow.
200 // *Requires* that "ptr" is already marked.
201 void push(oop ptr) {
202 if (isFull()) {
203 // Record overflow.
204 _overflow = true;
205 return;
206 } else {
207 _base[_index++] = ptr;
208 NOT_PRODUCT(_max_depth = MAX2(_max_depth, _index));
209 }
210 }
211 // Non-block impl. Note: concurrency is allowed only with other
212 // "par_push" operations, not with "pop" or "drain". We would need
213 // parallel versions of them if such concurrency was desired.
214 void par_push(oop ptr);
216 // Pushes the first "n" elements of "ptr_arr" on the stack.
217 // Non-block impl. Note: concurrency is allowed only with other
218 // "par_adjoin_arr" or "push" operations, not with "pop" or "drain".
219 void par_adjoin_arr(oop* ptr_arr, int n);
221 // Pushes the first "n" elements of "ptr_arr" on the stack.
222 // Locking impl: concurrency is allowed only with
223 // "par_push_arr" and/or "par_pop_arr" operations, which use the same
224 // locking strategy.
225 void par_push_arr(oop* ptr_arr, int n);
227 // If returns false, the array was empty. Otherwise, removes up to "max"
228 // elements from the stack, and transfers them to "ptr_arr" in an
229 // unspecified order. The actual number transferred is given in "n" ("n
230 // == 0" is deliberately redundant with the return value.) Locking impl:
231 // concurrency is allowed only with "par_push_arr" and/or "par_pop_arr"
232 // operations, which use the same locking strategy.
233 bool par_pop_arr(oop* ptr_arr, int max, int* n);
235 // Drain the mark stack, applying the given closure to all fields of
236 // objects on the stack. (That is, continue until the stack is empty,
237 // even if closure applications add entries to the stack.) The "bm"
238 // argument, if non-null, may be used to verify that only marked objects
239 // are on the mark stack. If "yield_after" is "true", then the
240 // concurrent marker performing the drain offers to yield after
241 // processing each object. If a yield occurs, stops the drain operation
242 // and returns false. Otherwise, returns true.
243 template<class OopClosureClass>
244 bool drain(OopClosureClass* cl, CMBitMap* bm, bool yield_after = false);
246 bool isEmpty() { return _index == 0; }
247 bool isFull() { return _index == _capacity; }
248 int maxElems() { return _capacity; }
250 bool overflow() { return _overflow; }
251 void clear_overflow() { _overflow = false; }
253 bool should_expand() const { return _should_expand; }
254 void set_should_expand();
256 // Expand the stack, typically in response to an overflow condition
257 void expand();
259 int size() { return _index; }
261 void setEmpty() { _index = 0; clear_overflow(); }
263 // Record the current index.
264 void note_start_of_gc();
266 // Make sure that we have not added any entries to the stack during GC.
267 void note_end_of_gc();
269 // iterate over the oops in the mark stack, up to the bound recorded via
270 // the call above.
271 void oops_do(OopClosure* f);
272 };
274 class ForceOverflowSettings VALUE_OBJ_CLASS_SPEC {
275 private:
276 #ifndef PRODUCT
277 uintx _num_remaining;
278 bool _force;
279 #endif // !defined(PRODUCT)
281 public:
282 void init() PRODUCT_RETURN;
283 void update() PRODUCT_RETURN;
284 bool should_force() PRODUCT_RETURN_( return false; );
285 };
287 // this will enable a variety of different statistics per GC task
288 #define _MARKING_STATS_ 0
289 // this will enable the higher verbose levels
290 #define _MARKING_VERBOSE_ 0
292 #if _MARKING_STATS_
293 #define statsOnly(statement) \
294 do { \
295 statement ; \
296 } while (0)
297 #else // _MARKING_STATS_
298 #define statsOnly(statement) \
299 do { \
300 } while (0)
301 #endif // _MARKING_STATS_
303 typedef enum {
304 no_verbose = 0, // verbose turned off
305 stats_verbose, // only prints stats at the end of marking
306 low_verbose, // low verbose, mostly per region and per major event
307 medium_verbose, // a bit more detailed than low
308 high_verbose // per object verbose
309 } CMVerboseLevel;
311 class YoungList;
313 // Root Regions are regions that are not empty at the beginning of a
314 // marking cycle and which we might collect during an evacuation pause
315 // while the cycle is active. Given that, during evacuation pauses, we
316 // do not copy objects that are explicitly marked, what we have to do
317 // for the root regions is to scan them and mark all objects reachable
318 // from them. According to the SATB assumptions, we only need to visit
319 // each object once during marking. So, as long as we finish this scan
320 // before the next evacuation pause, we can copy the objects from the
321 // root regions without having to mark them or do anything else to them.
322 //
323 // Currently, we only support root region scanning once (at the start
324 // of the marking cycle) and the root regions are all the survivor
325 // regions populated during the initial-mark pause.
326 class CMRootRegions VALUE_OBJ_CLASS_SPEC {
327 private:
328 YoungList* _young_list;
329 ConcurrentMark* _cm;
331 volatile bool _scan_in_progress;
332 volatile bool _should_abort;
333 HeapRegion* volatile _next_survivor;
335 public:
336 CMRootRegions();
337 // We actually do most of the initialization in this method.
338 void init(G1CollectedHeap* g1h, ConcurrentMark* cm);
340 // Reset the claiming / scanning of the root regions.
341 void prepare_for_scan();
343 // Forces get_next() to return NULL so that the iteration aborts early.
344 void abort() { _should_abort = true; }
346 // Return true if the CM thread are actively scanning root regions,
347 // false otherwise.
348 bool scan_in_progress() { return _scan_in_progress; }
350 // Claim the next root region to scan atomically, or return NULL if
351 // all have been claimed.
352 HeapRegion* claim_next();
354 // Flag that we're done with root region scanning and notify anyone
355 // who's waiting on it. If aborted is false, assume that all regions
356 // have been claimed.
357 void scan_finished();
359 // If CM threads are still scanning root regions, wait until they
360 // are done. Return true if we had to wait, false otherwise.
361 bool wait_until_scan_finished();
362 };
364 class ConcurrentMarkThread;
366 class ConcurrentMark: public CHeapObj<mtGC> {
367 friend class CMMarkStack;
368 friend class ConcurrentMarkThread;
369 friend class CMTask;
370 friend class CMBitMapClosure;
371 friend class CMGlobalObjectClosure;
372 friend class CMRemarkTask;
373 friend class CMConcurrentMarkingTask;
374 friend class G1ParNoteEndTask;
375 friend class CalcLiveObjectsClosure;
376 friend class G1CMRefProcTaskProxy;
377 friend class G1CMRefProcTaskExecutor;
378 friend class G1CMKeepAliveAndDrainClosure;
379 friend class G1CMDrainMarkingStackClosure;
381 protected:
382 ConcurrentMarkThread* _cmThread; // the thread doing the work
383 G1CollectedHeap* _g1h; // the heap.
384 uint _parallel_marking_threads; // the number of marking
385 // threads we're use
386 uint _max_parallel_marking_threads; // max number of marking
387 // threads we'll ever use
388 double _sleep_factor; // how much we have to sleep, with
389 // respect to the work we just did, to
390 // meet the marking overhead goal
391 double _marking_task_overhead; // marking target overhead for
392 // a single task
394 // same as the two above, but for the cleanup task
395 double _cleanup_sleep_factor;
396 double _cleanup_task_overhead;
398 FreeRegionList _cleanup_list;
400 // Concurrent marking support structures
401 CMBitMap _markBitMap1;
402 CMBitMap _markBitMap2;
403 CMBitMapRO* _prevMarkBitMap; // completed mark bitmap
404 CMBitMap* _nextMarkBitMap; // under-construction mark bitmap
406 BitMap _region_bm;
407 BitMap _card_bm;
409 // Heap bounds
410 HeapWord* _heap_start;
411 HeapWord* _heap_end;
413 // Root region tracking and claiming.
414 CMRootRegions _root_regions;
416 // For gray objects
417 CMMarkStack _markStack; // Grey objects behind global finger.
418 HeapWord* volatile _finger; // the global finger, region aligned,
419 // always points to the end of the
420 // last claimed region
422 // marking tasks
423 uint _max_worker_id;// maximum worker id
424 uint _active_tasks; // task num currently active
425 CMTask** _tasks; // task queue array (max_worker_id len)
426 CMTaskQueueSet* _task_queues; // task queue set
427 ParallelTaskTerminator _terminator; // for termination
429 // Two sync barriers that are used to synchronise tasks when an
430 // overflow occurs. The algorithm is the following. All tasks enter
431 // the first one to ensure that they have all stopped manipulating
432 // the global data structures. After they exit it, they re-initialise
433 // their data structures and task 0 re-initialises the global data
434 // structures. Then, they enter the second sync barrier. This
435 // ensure, that no task starts doing work before all data
436 // structures (local and global) have been re-initialised. When they
437 // exit it, they are free to start working again.
438 WorkGangBarrierSync _first_overflow_barrier_sync;
439 WorkGangBarrierSync _second_overflow_barrier_sync;
441 // this is set by any task, when an overflow on the global data
442 // structures is detected.
443 volatile bool _has_overflown;
444 // true: marking is concurrent, false: we're in remark
445 volatile bool _concurrent;
446 // set at the end of a Full GC so that marking aborts
447 volatile bool _has_aborted;
448 GCId _aborted_gc_id;
450 // used when remark aborts due to an overflow to indicate that
451 // another concurrent marking phase should start
452 volatile bool _restart_for_overflow;
454 // This is true from the very start of concurrent marking until the
455 // point when all the tasks complete their work. It is really used
456 // to determine the points between the end of concurrent marking and
457 // time of remark.
458 volatile bool _concurrent_marking_in_progress;
460 // verbose level
461 CMVerboseLevel _verbose_level;
463 // All of these times are in ms.
464 NumberSeq _init_times;
465 NumberSeq _remark_times;
466 NumberSeq _remark_mark_times;
467 NumberSeq _remark_weak_ref_times;
468 NumberSeq _cleanup_times;
469 double _total_counting_time;
470 double _total_rs_scrub_time;
472 double* _accum_task_vtime; // accumulated task vtime
474 FlexibleWorkGang* _parallel_workers;
476 ForceOverflowSettings _force_overflow_conc;
477 ForceOverflowSettings _force_overflow_stw;
479 void weakRefsWork(bool clear_all_soft_refs);
481 void swapMarkBitMaps();
483 // It resets the global marking data structures, as well as the
484 // task local ones; should be called during initial mark.
485 void reset();
487 // Resets all the marking data structures. Called when we have to restart
488 // marking or when marking completes (via set_non_marking_state below).
489 void reset_marking_state(bool clear_overflow = true);
491 // We do this after we're done with marking so that the marking data
492 // structures are initialised to a sensible and predictable state.
493 void set_non_marking_state();
495 // Called to indicate how many threads are currently active.
496 void set_concurrency(uint active_tasks);
498 // It should be called to indicate which phase we're in (concurrent
499 // mark or remark) and how many threads are currently active.
500 void set_concurrency_and_phase(uint active_tasks, bool concurrent);
502 // prints all gathered CM-related statistics
503 void print_stats();
505 bool cleanup_list_is_empty() {
506 return _cleanup_list.is_empty();
507 }
509 // accessor methods
510 uint parallel_marking_threads() const { return _parallel_marking_threads; }
511 uint max_parallel_marking_threads() const { return _max_parallel_marking_threads;}
512 double sleep_factor() { return _sleep_factor; }
513 double marking_task_overhead() { return _marking_task_overhead;}
514 double cleanup_sleep_factor() { return _cleanup_sleep_factor; }
515 double cleanup_task_overhead() { return _cleanup_task_overhead;}
517 bool use_parallel_marking_threads() const {
518 assert(parallel_marking_threads() <=
519 max_parallel_marking_threads(), "sanity");
520 assert((_parallel_workers == NULL && parallel_marking_threads() == 0) ||
521 parallel_marking_threads() > 0,
522 "parallel workers not set up correctly");
523 return _parallel_workers != NULL;
524 }
526 HeapWord* finger() { return _finger; }
527 bool concurrent() { return _concurrent; }
528 uint active_tasks() { return _active_tasks; }
529 ParallelTaskTerminator* terminator() { return &_terminator; }
531 // It claims the next available region to be scanned by a marking
532 // task/thread. It might return NULL if the next region is empty or
533 // we have run out of regions. In the latter case, out_of_regions()
534 // determines whether we've really run out of regions or the task
535 // should call claim_region() again. This might seem a bit
536 // awkward. Originally, the code was written so that claim_region()
537 // either successfully returned with a non-empty region or there
538 // were no more regions to be claimed. The problem with this was
539 // that, in certain circumstances, it iterated over large chunks of
540 // the heap finding only empty regions and, while it was working, it
541 // was preventing the calling task to call its regular clock
542 // method. So, this way, each task will spend very little time in
543 // claim_region() and is allowed to call the regular clock method
544 // frequently.
545 HeapRegion* claim_region(uint worker_id);
547 // It determines whether we've run out of regions to scan. Note that
548 // the finger can point past the heap end in case the heap was expanded
549 // to satisfy an allocation without doing a GC. This is fine, because all
550 // objects in those regions will be considered live anyway because of
551 // SATB guarantees (i.e. their TAMS will be equal to bottom).
552 bool out_of_regions() { return _finger >= _heap_end; }
554 // Returns the task with the given id
555 CMTask* task(int id) {
556 assert(0 <= id && id < (int) _active_tasks,
557 "task id not within active bounds");
558 return _tasks[id];
559 }
561 // Returns the task queue with the given id
562 CMTaskQueue* task_queue(int id) {
563 assert(0 <= id && id < (int) _active_tasks,
564 "task queue id not within active bounds");
565 return (CMTaskQueue*) _task_queues->queue(id);
566 }
568 // Returns the task queue set
569 CMTaskQueueSet* task_queues() { return _task_queues; }
571 // Access / manipulation of the overflow flag which is set to
572 // indicate that the global stack has overflown
573 bool has_overflown() { return _has_overflown; }
574 void set_has_overflown() { _has_overflown = true; }
575 void clear_has_overflown() { _has_overflown = false; }
576 bool restart_for_overflow() { return _restart_for_overflow; }
578 // Methods to enter the two overflow sync barriers
579 void enter_first_sync_barrier(uint worker_id);
580 void enter_second_sync_barrier(uint worker_id);
582 ForceOverflowSettings* force_overflow_conc() {
583 return &_force_overflow_conc;
584 }
586 ForceOverflowSettings* force_overflow_stw() {
587 return &_force_overflow_stw;
588 }
590 ForceOverflowSettings* force_overflow() {
591 if (concurrent()) {
592 return force_overflow_conc();
593 } else {
594 return force_overflow_stw();
595 }
596 }
598 // Live Data Counting data structures...
599 // These data structures are initialized at the start of
600 // marking. They are written to while marking is active.
601 // They are aggregated during remark; the aggregated values
602 // are then used to populate the _region_bm, _card_bm, and
603 // the total live bytes, which are then subsequently updated
604 // during cleanup.
606 // An array of bitmaps (one bit map per task). Each bitmap
607 // is used to record the cards spanned by the live objects
608 // marked by that task/worker.
609 BitMap* _count_card_bitmaps;
611 // Used to record the number of marked live bytes
612 // (for each region, by worker thread).
613 size_t** _count_marked_bytes;
615 // Card index of the bottom of the G1 heap. Used for biasing indices into
616 // the card bitmaps.
617 intptr_t _heap_bottom_card_num;
619 // Set to true when initialization is complete
620 bool _completed_initialization;
622 public:
623 // Manipulation of the global mark stack.
624 // Notice that the first mark_stack_push is CAS-based, whereas the
625 // two below are Mutex-based. This is OK since the first one is only
626 // called during evacuation pauses and doesn't compete with the
627 // other two (which are called by the marking tasks during
628 // concurrent marking or remark).
629 bool mark_stack_push(oop p) {
630 _markStack.par_push(p);
631 if (_markStack.overflow()) {
632 set_has_overflown();
633 return false;
634 }
635 return true;
636 }
637 bool mark_stack_push(oop* arr, int n) {
638 _markStack.par_push_arr(arr, n);
639 if (_markStack.overflow()) {
640 set_has_overflown();
641 return false;
642 }
643 return true;
644 }
645 void mark_stack_pop(oop* arr, int max, int* n) {
646 _markStack.par_pop_arr(arr, max, n);
647 }
648 size_t mark_stack_size() { return _markStack.size(); }
649 size_t partial_mark_stack_size_target() { return _markStack.maxElems()/3; }
650 bool mark_stack_overflow() { return _markStack.overflow(); }
651 bool mark_stack_empty() { return _markStack.isEmpty(); }
653 CMRootRegions* root_regions() { return &_root_regions; }
655 bool concurrent_marking_in_progress() {
656 return _concurrent_marking_in_progress;
657 }
658 void set_concurrent_marking_in_progress() {
659 _concurrent_marking_in_progress = true;
660 }
661 void clear_concurrent_marking_in_progress() {
662 _concurrent_marking_in_progress = false;
663 }
665 void update_accum_task_vtime(int i, double vtime) {
666 _accum_task_vtime[i] += vtime;
667 }
669 double all_task_accum_vtime() {
670 double ret = 0.0;
671 for (uint i = 0; i < _max_worker_id; ++i)
672 ret += _accum_task_vtime[i];
673 return ret;
674 }
676 // Attempts to steal an object from the task queues of other tasks
677 bool try_stealing(uint worker_id, int* hash_seed, oop& obj) {
678 return _task_queues->steal(worker_id, hash_seed, obj);
679 }
681 ConcurrentMark(G1CollectedHeap* g1h, ReservedSpace heap_rs);
682 ~ConcurrentMark();
684 ConcurrentMarkThread* cmThread() { return _cmThread; }
686 CMBitMapRO* prevMarkBitMap() const { return _prevMarkBitMap; }
687 CMBitMap* nextMarkBitMap() const { return _nextMarkBitMap; }
689 // Returns the number of GC threads to be used in a concurrent
690 // phase based on the number of GC threads being used in a STW
691 // phase.
692 uint scale_parallel_threads(uint n_par_threads);
694 // Calculates the number of GC threads to be used in a concurrent phase.
695 uint calc_parallel_marking_threads();
697 // The following three are interaction between CM and
698 // G1CollectedHeap
700 // This notifies CM that a root during initial-mark needs to be
701 // grayed. It is MT-safe. word_size is the size of the object in
702 // words. It is passed explicitly as sometimes we cannot calculate
703 // it from the given object because it might be in an inconsistent
704 // state (e.g., in to-space and being copied). So the caller is
705 // responsible for dealing with this issue (e.g., get the size from
706 // the from-space image when the to-space image might be
707 // inconsistent) and always passing the size. hr is the region that
708 // contains the object and it's passed optionally from callers who
709 // might already have it (no point in recalculating it).
710 inline void grayRoot(oop obj, size_t word_size,
711 uint worker_id, HeapRegion* hr = NULL);
713 // It iterates over the heap and for each object it comes across it
714 // will dump the contents of its reference fields, as well as
715 // liveness information for the object and its referents. The dump
716 // will be written to a file with the following name:
717 // G1PrintReachableBaseFile + "." + str.
718 // vo decides whether the prev (vo == UsePrevMarking), the next
719 // (vo == UseNextMarking) marking information, or the mark word
720 // (vo == UseMarkWord) will be used to determine the liveness of
721 // each object / referent.
722 // If all is true, all objects in the heap will be dumped, otherwise
723 // only the live ones. In the dump the following symbols / breviations
724 // are used:
725 // M : an explicitly live object (its bitmap bit is set)
726 // > : an implicitly live object (over tams)
727 // O : an object outside the G1 heap (typically: in the perm gen)
728 // NOT : a reference field whose referent is not live
729 // AND MARKED : indicates that an object is both explicitly and
730 // implicitly live (it should be one or the other, not both)
731 void print_reachable(const char* str,
732 VerifyOption vo, bool all) PRODUCT_RETURN;
734 // Clear the next marking bitmap (will be called concurrently).
735 void clearNextBitmap();
737 // These two do the work that needs to be done before and after the
738 // initial root checkpoint. Since this checkpoint can be done at two
739 // different points (i.e. an explicit pause or piggy-backed on a
740 // young collection), then it's nice to be able to easily share the
741 // pre/post code. It might be the case that we can put everything in
742 // the post method. TP
743 void checkpointRootsInitialPre();
744 void checkpointRootsInitialPost();
746 // Scan all the root regions and mark everything reachable from
747 // them.
748 void scanRootRegions();
750 // Scan a single root region and mark everything reachable from it.
751 void scanRootRegion(HeapRegion* hr, uint worker_id);
753 // Do concurrent phase of marking, to a tentative transitive closure.
754 void markFromRoots();
756 void checkpointRootsFinal(bool clear_all_soft_refs);
757 void checkpointRootsFinalWork();
758 void cleanup();
759 void completeCleanup();
761 // Mark in the previous bitmap. NB: this is usually read-only, so use
762 // this carefully!
763 inline void markPrev(oop p);
765 // Clears marks for all objects in the given range, for the prev,
766 // next, or both bitmaps. NB: the previous bitmap is usually
767 // read-only, so use this carefully!
768 void clearRangePrevBitmap(MemRegion mr);
769 void clearRangeNextBitmap(MemRegion mr);
770 void clearRangeBothBitmaps(MemRegion mr);
772 // Notify data structures that a GC has started.
773 void note_start_of_gc() {
774 _markStack.note_start_of_gc();
775 }
777 // Notify data structures that a GC is finished.
778 void note_end_of_gc() {
779 _markStack.note_end_of_gc();
780 }
782 // Verify that there are no CSet oops on the stacks (taskqueues /
783 // global mark stack), enqueued SATB buffers, per-thread SATB
784 // buffers, and fingers (global / per-task). The boolean parameters
785 // decide which of the above data structures to verify. If marking
786 // is not in progress, it's a no-op.
787 void verify_no_cset_oops(bool verify_stacks,
788 bool verify_enqueued_buffers,
789 bool verify_thread_buffers,
790 bool verify_fingers) PRODUCT_RETURN;
792 // It is called at the end of an evacuation pause during marking so
793 // that CM is notified of where the new end of the heap is. It
794 // doesn't do anything if concurrent_marking_in_progress() is false,
795 // unless the force parameter is true.
796 void update_g1_committed(bool force = false);
798 bool isMarked(oop p) const {
799 assert(p != NULL && p->is_oop(), "expected an oop");
800 HeapWord* addr = (HeapWord*)p;
801 assert(addr >= _nextMarkBitMap->startWord() ||
802 addr < _nextMarkBitMap->endWord(), "in a region");
804 return _nextMarkBitMap->isMarked(addr);
805 }
807 inline bool not_yet_marked(oop p) const;
809 // XXX Debug code
810 bool containing_card_is_marked(void* p);
811 bool containing_cards_are_marked(void* start, void* last);
813 bool isPrevMarked(oop p) const {
814 assert(p != NULL && p->is_oop(), "expected an oop");
815 HeapWord* addr = (HeapWord*)p;
816 assert(addr >= _prevMarkBitMap->startWord() ||
817 addr < _prevMarkBitMap->endWord(), "in a region");
819 return _prevMarkBitMap->isMarked(addr);
820 }
822 inline bool do_yield_check(uint worker_i = 0);
823 inline bool should_yield();
825 // Called to abort the marking cycle after a Full GC takes palce.
826 void abort();
828 bool has_aborted() { return _has_aborted; }
830 const GCId& concurrent_gc_id();
832 // This prints the global/local fingers. It is used for debugging.
833 NOT_PRODUCT(void print_finger();)
835 void print_summary_info();
837 void print_worker_threads_on(outputStream* st) const;
839 void print_on_error(outputStream* st) const;
841 // The following indicate whether a given verbose level has been
842 // set. Notice that anything above stats is conditional to
843 // _MARKING_VERBOSE_ having been set to 1
844 bool verbose_stats() {
845 return _verbose_level >= stats_verbose;
846 }
847 bool verbose_low() {
848 return _MARKING_VERBOSE_ && _verbose_level >= low_verbose;
849 }
850 bool verbose_medium() {
851 return _MARKING_VERBOSE_ && _verbose_level >= medium_verbose;
852 }
853 bool verbose_high() {
854 return _MARKING_VERBOSE_ && _verbose_level >= high_verbose;
855 }
857 // Liveness counting
859 // Utility routine to set an exclusive range of cards on the given
860 // card liveness bitmap
861 inline void set_card_bitmap_range(BitMap* card_bm,
862 BitMap::idx_t start_idx,
863 BitMap::idx_t end_idx,
864 bool is_par);
866 // Returns the card number of the bottom of the G1 heap.
867 // Used in biasing indices into accounting card bitmaps.
868 intptr_t heap_bottom_card_num() const {
869 return _heap_bottom_card_num;
870 }
872 // Returns the card bitmap for a given task or worker id.
873 BitMap* count_card_bitmap_for(uint worker_id) {
874 assert(0 <= worker_id && worker_id < _max_worker_id, "oob");
875 assert(_count_card_bitmaps != NULL, "uninitialized");
876 BitMap* task_card_bm = &_count_card_bitmaps[worker_id];
877 assert(task_card_bm->size() == _card_bm.size(), "size mismatch");
878 return task_card_bm;
879 }
881 // Returns the array containing the marked bytes for each region,
882 // for the given worker or task id.
883 size_t* count_marked_bytes_array_for(uint worker_id) {
884 assert(0 <= worker_id && worker_id < _max_worker_id, "oob");
885 assert(_count_marked_bytes != NULL, "uninitialized");
886 size_t* marked_bytes_array = _count_marked_bytes[worker_id];
887 assert(marked_bytes_array != NULL, "uninitialized");
888 return marked_bytes_array;
889 }
891 // Returns the index in the liveness accounting card table bitmap
892 // for the given address
893 inline BitMap::idx_t card_bitmap_index_for(HeapWord* addr);
895 // Counts the size of the given memory region in the the given
896 // marked_bytes array slot for the given HeapRegion.
897 // Sets the bits in the given card bitmap that are associated with the
898 // cards that are spanned by the memory region.
899 inline void count_region(MemRegion mr, HeapRegion* hr,
900 size_t* marked_bytes_array,
901 BitMap* task_card_bm);
903 // Counts the given memory region in the task/worker counting
904 // data structures for the given worker id.
905 inline void count_region(MemRegion mr, HeapRegion* hr, uint worker_id);
907 // Counts the given memory region in the task/worker counting
908 // data structures for the given worker id.
909 inline void count_region(MemRegion mr, uint worker_id);
911 // Counts the given object in the given task/worker counting
912 // data structures.
913 inline void count_object(oop obj, HeapRegion* hr,
914 size_t* marked_bytes_array,
915 BitMap* task_card_bm);
917 // Counts the given object in the task/worker counting data
918 // structures for the given worker id.
919 inline void count_object(oop obj, HeapRegion* hr, uint worker_id);
921 // Attempts to mark the given object and, if successful, counts
922 // the object in the given task/worker counting structures.
923 inline bool par_mark_and_count(oop obj, HeapRegion* hr,
924 size_t* marked_bytes_array,
925 BitMap* task_card_bm);
927 // Attempts to mark the given object and, if successful, counts
928 // the object in the task/worker counting structures for the
929 // given worker id.
930 inline bool par_mark_and_count(oop obj, size_t word_size,
931 HeapRegion* hr, uint worker_id);
933 // Attempts to mark the given object and, if successful, counts
934 // the object in the task/worker counting structures for the
935 // given worker id.
936 inline bool par_mark_and_count(oop obj, HeapRegion* hr, uint worker_id);
938 // Similar to the above routine but we don't know the heap region that
939 // contains the object to be marked/counted, which this routine looks up.
940 inline bool par_mark_and_count(oop obj, uint worker_id);
942 // Similar to the above routine but there are times when we cannot
943 // safely calculate the size of obj due to races and we, therefore,
944 // pass the size in as a parameter. It is the caller's reponsibility
945 // to ensure that the size passed in for obj is valid.
946 inline bool par_mark_and_count(oop obj, size_t word_size, uint worker_id);
948 // Unconditionally mark the given object, and unconditinally count
949 // the object in the counting structures for worker id 0.
950 // Should *not* be called from parallel code.
951 inline bool mark_and_count(oop obj, HeapRegion* hr);
953 // Similar to the above routine but we don't know the heap region that
954 // contains the object to be marked/counted, which this routine looks up.
955 // Should *not* be called from parallel code.
956 inline bool mark_and_count(oop obj);
958 // Returns true if initialization was successfully completed.
959 bool completed_initialization() const {
960 return _completed_initialization;
961 }
963 protected:
964 // Clear all the per-task bitmaps and arrays used to store the
965 // counting data.
966 void clear_all_count_data();
968 // Aggregates the counting data for each worker/task
969 // that was constructed while marking. Also sets
970 // the amount of marked bytes for each region and
971 // the top at concurrent mark count.
972 void aggregate_count_data();
974 // Verification routine
975 void verify_count_data();
976 };
978 // A class representing a marking task.
979 class CMTask : public TerminatorTerminator {
980 private:
981 enum PrivateConstants {
982 // the regular clock call is called once the scanned words reaches
983 // this limit
984 words_scanned_period = 12*1024,
985 // the regular clock call is called once the number of visited
986 // references reaches this limit
987 refs_reached_period = 384,
988 // initial value for the hash seed, used in the work stealing code
989 init_hash_seed = 17,
990 // how many entries will be transferred between global stack and
991 // local queues
992 global_stack_transfer_size = 16
993 };
995 uint _worker_id;
996 G1CollectedHeap* _g1h;
997 ConcurrentMark* _cm;
998 CMBitMap* _nextMarkBitMap;
999 // the task queue of this task
1000 CMTaskQueue* _task_queue;
1001 private:
1002 // the task queue set---needed for stealing
1003 CMTaskQueueSet* _task_queues;
1004 // indicates whether the task has been claimed---this is only for
1005 // debugging purposes
1006 bool _claimed;
1008 // number of calls to this task
1009 int _calls;
1011 // when the virtual timer reaches this time, the marking step should
1012 // exit
1013 double _time_target_ms;
1014 // the start time of the current marking step
1015 double _start_time_ms;
1017 // the oop closure used for iterations over oops
1018 G1CMOopClosure* _cm_oop_closure;
1020 // the region this task is scanning, NULL if we're not scanning any
1021 HeapRegion* _curr_region;
1022 // the local finger of this task, NULL if we're not scanning a region
1023 HeapWord* _finger;
1024 // limit of the region this task is scanning, NULL if we're not scanning one
1025 HeapWord* _region_limit;
1027 // the number of words this task has scanned
1028 size_t _words_scanned;
1029 // When _words_scanned reaches this limit, the regular clock is
1030 // called. Notice that this might be decreased under certain
1031 // circumstances (i.e. when we believe that we did an expensive
1032 // operation).
1033 size_t _words_scanned_limit;
1034 // the initial value of _words_scanned_limit (i.e. what it was
1035 // before it was decreased).
1036 size_t _real_words_scanned_limit;
1038 // the number of references this task has visited
1039 size_t _refs_reached;
1040 // When _refs_reached reaches this limit, the regular clock is
1041 // called. Notice this this might be decreased under certain
1042 // circumstances (i.e. when we believe that we did an expensive
1043 // operation).
1044 size_t _refs_reached_limit;
1045 // the initial value of _refs_reached_limit (i.e. what it was before
1046 // it was decreased).
1047 size_t _real_refs_reached_limit;
1049 // used by the work stealing stuff
1050 int _hash_seed;
1051 // if this is true, then the task has aborted for some reason
1052 bool _has_aborted;
1053 // set when the task aborts because it has met its time quota
1054 bool _has_timed_out;
1055 // true when we're draining SATB buffers; this avoids the task
1056 // aborting due to SATB buffers being available (as we're already
1057 // dealing with them)
1058 bool _draining_satb_buffers;
1060 // number sequence of past step times
1061 NumberSeq _step_times_ms;
1062 // elapsed time of this task
1063 double _elapsed_time_ms;
1064 // termination time of this task
1065 double _termination_time_ms;
1066 // when this task got into the termination protocol
1067 double _termination_start_time_ms;
1069 // true when the task is during a concurrent phase, false when it is
1070 // in the remark phase (so, in the latter case, we do not have to
1071 // check all the things that we have to check during the concurrent
1072 // phase, i.e. SATB buffer availability...)
1073 bool _concurrent;
1075 TruncatedSeq _marking_step_diffs_ms;
1077 // Counting data structures. Embedding the task's marked_bytes_array
1078 // and card bitmap into the actual task saves having to go through
1079 // the ConcurrentMark object.
1080 size_t* _marked_bytes_array;
1081 BitMap* _card_bm;
1083 // LOTS of statistics related with this task
1084 #if _MARKING_STATS_
1085 NumberSeq _all_clock_intervals_ms;
1086 double _interval_start_time_ms;
1088 int _aborted;
1089 int _aborted_overflow;
1090 int _aborted_cm_aborted;
1091 int _aborted_yield;
1092 int _aborted_timed_out;
1093 int _aborted_satb;
1094 int _aborted_termination;
1096 int _steal_attempts;
1097 int _steals;
1099 int _clock_due_to_marking;
1100 int _clock_due_to_scanning;
1102 int _local_pushes;
1103 int _local_pops;
1104 int _local_max_size;
1105 int _objs_scanned;
1107 int _global_pushes;
1108 int _global_pops;
1109 int _global_max_size;
1111 int _global_transfers_to;
1112 int _global_transfers_from;
1114 int _regions_claimed;
1115 int _objs_found_on_bitmap;
1117 int _satb_buffers_processed;
1118 #endif // _MARKING_STATS_
1120 // it updates the local fields after this task has claimed
1121 // a new region to scan
1122 void setup_for_region(HeapRegion* hr);
1123 // it brings up-to-date the limit of the region
1124 void update_region_limit();
1126 // called when either the words scanned or the refs visited limit
1127 // has been reached
1128 void reached_limit();
1129 // recalculates the words scanned and refs visited limits
1130 void recalculate_limits();
1131 // decreases the words scanned and refs visited limits when we reach
1132 // an expensive operation
1133 void decrease_limits();
1134 // it checks whether the words scanned or refs visited reached their
1135 // respective limit and calls reached_limit() if they have
1136 void check_limits() {
1137 if (_words_scanned >= _words_scanned_limit ||
1138 _refs_reached >= _refs_reached_limit) {
1139 reached_limit();
1140 }
1141 }
1142 // this is supposed to be called regularly during a marking step as
1143 // it checks a bunch of conditions that might cause the marking step
1144 // to abort
1145 void regular_clock_call();
1146 bool concurrent() { return _concurrent; }
1148 public:
1149 // It resets the task; it should be called right at the beginning of
1150 // a marking phase.
1151 void reset(CMBitMap* _nextMarkBitMap);
1152 // it clears all the fields that correspond to a claimed region.
1153 void clear_region_fields();
1155 void set_concurrent(bool concurrent) { _concurrent = concurrent; }
1157 // The main method of this class which performs a marking step
1158 // trying not to exceed the given duration. However, it might exit
1159 // prematurely, according to some conditions (i.e. SATB buffers are
1160 // available for processing).
1161 void do_marking_step(double target_ms,
1162 bool do_termination,
1163 bool is_serial);
1165 // These two calls start and stop the timer
1166 void record_start_time() {
1167 _elapsed_time_ms = os::elapsedTime() * 1000.0;
1168 }
1169 void record_end_time() {
1170 _elapsed_time_ms = os::elapsedTime() * 1000.0 - _elapsed_time_ms;
1171 }
1173 // returns the worker ID associated with this task.
1174 uint worker_id() { return _worker_id; }
1176 // From TerminatorTerminator. It determines whether this task should
1177 // exit the termination protocol after it's entered it.
1178 virtual bool should_exit_termination();
1180 // Resets the local region fields after a task has finished scanning a
1181 // region; or when they have become stale as a result of the region
1182 // being evacuated.
1183 void giveup_current_region();
1185 HeapWord* finger() { return _finger; }
1187 bool has_aborted() { return _has_aborted; }
1188 void set_has_aborted() { _has_aborted = true; }
1189 void clear_has_aborted() { _has_aborted = false; }
1190 bool has_timed_out() { return _has_timed_out; }
1191 bool claimed() { return _claimed; }
1193 void set_cm_oop_closure(G1CMOopClosure* cm_oop_closure);
1195 // It grays the object by marking it and, if necessary, pushing it
1196 // on the local queue
1197 inline void deal_with_reference(oop obj);
1199 // It scans an object and visits its children.
1200 void scan_object(oop obj);
1202 // It pushes an object on the local queue.
1203 inline void push(oop obj);
1205 // These two move entries to/from the global stack.
1206 void move_entries_to_global_stack();
1207 void get_entries_from_global_stack();
1209 // It pops and scans objects from the local queue. If partially is
1210 // true, then it stops when the queue size is of a given limit. If
1211 // partially is false, then it stops when the queue is empty.
1212 void drain_local_queue(bool partially);
1213 // It moves entries from the global stack to the local queue and
1214 // drains the local queue. If partially is true, then it stops when
1215 // both the global stack and the local queue reach a given size. If
1216 // partially if false, it tries to empty them totally.
1217 void drain_global_stack(bool partially);
1218 // It keeps picking SATB buffers and processing them until no SATB
1219 // buffers are available.
1220 void drain_satb_buffers();
1222 // moves the local finger to a new location
1223 inline void move_finger_to(HeapWord* new_finger) {
1224 assert(new_finger >= _finger && new_finger < _region_limit, "invariant");
1225 _finger = new_finger;
1226 }
1228 CMTask(uint worker_id, ConcurrentMark *cm,
1229 size_t* marked_bytes, BitMap* card_bm,
1230 CMTaskQueue* task_queue, CMTaskQueueSet* task_queues);
1232 // it prints statistics associated with this task
1233 void print_stats();
1235 #if _MARKING_STATS_
1236 void increase_objs_found_on_bitmap() { ++_objs_found_on_bitmap; }
1237 #endif // _MARKING_STATS_
1238 };
1240 // Class that's used to to print out per-region liveness
1241 // information. It's currently used at the end of marking and also
1242 // after we sort the old regions at the end of the cleanup operation.
1243 class G1PrintRegionLivenessInfoClosure: public HeapRegionClosure {
1244 private:
1245 outputStream* _out;
1247 // Accumulators for these values.
1248 size_t _total_used_bytes;
1249 size_t _total_capacity_bytes;
1250 size_t _total_prev_live_bytes;
1251 size_t _total_next_live_bytes;
1253 // These are set up when we come across a "stars humongous" region
1254 // (as this is where most of this information is stored, not in the
1255 // subsequent "continues humongous" regions). After that, for every
1256 // region in a given humongous region series we deduce the right
1257 // values for it by simply subtracting the appropriate amount from
1258 // these fields. All these values should reach 0 after we've visited
1259 // the last region in the series.
1260 size_t _hum_used_bytes;
1261 size_t _hum_capacity_bytes;
1262 size_t _hum_prev_live_bytes;
1263 size_t _hum_next_live_bytes;
1265 // Accumulator for the remembered set size
1266 size_t _total_remset_bytes;
1268 // Accumulator for strong code roots memory size
1269 size_t _total_strong_code_roots_bytes;
1271 static double perc(size_t val, size_t total) {
1272 if (total == 0) {
1273 return 0.0;
1274 } else {
1275 return 100.0 * ((double) val / (double) total);
1276 }
1277 }
1279 static double bytes_to_mb(size_t val) {
1280 return (double) val / (double) M;
1281 }
1283 // See the .cpp file.
1284 size_t get_hum_bytes(size_t* hum_bytes);
1285 void get_hum_bytes(size_t* used_bytes, size_t* capacity_bytes,
1286 size_t* prev_live_bytes, size_t* next_live_bytes);
1288 public:
1289 // The header and footer are printed in the constructor and
1290 // destructor respectively.
1291 G1PrintRegionLivenessInfoClosure(outputStream* out, const char* phase_name);
1292 virtual bool doHeapRegion(HeapRegion* r);
1293 ~G1PrintRegionLivenessInfoClosure();
1294 };
1296 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTMARK_HPP