1 /*
2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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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).
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24
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP
27
28 #include "gc_implementation/g1/g1AllocationContext.hpp"
29 #include "gc_implementation/g1/g1Allocator.hpp"
30 #include "gc_implementation/g1/concurrentMark.hpp"
31 #include "gc_implementation/g1/evacuationInfo.hpp"
32 #include "gc_implementation/g1/g1AllocRegion.hpp"
33 #include "gc_implementation/g1/g1BiasedArray.hpp"
34 #include "gc_implementation/g1/g1HRPrinter.hpp"
35 #include "gc_implementation/g1/g1InCSetState.hpp"
36 #include "gc_implementation/g1/g1MonitoringSupport.hpp"
37 #include "gc_implementation/g1/g1SATBCardTableModRefBS.hpp"
38 #include "gc_implementation/g1/g1YCTypes.hpp"
39 #include "gc_implementation/g1/heapRegionManager.hpp"
40 #include "gc_implementation/g1/heapRegionSet.hpp"
41 #include "gc_implementation/shared/hSpaceCounters.hpp"
42 #include "gc_implementation/shared/parGCAllocBuffer.hpp"
43 #include "memory/barrierSet.hpp"
44 #include "memory/memRegion.hpp"
45 #include "memory/sharedHeap.hpp"
46 #include "utilities/stack.hpp"
47
48 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
49 // It uses the "Garbage First" heap organization and algorithm, which
50 // may combine concurrent marking with parallel, incremental compaction of
51 // heap subsets that will yield large amounts of garbage.
52
53 // Forward declarations
54 class HeapRegion;
55 class HRRSCleanupTask;
56 class GenerationSpec;
57 class OopsInHeapRegionClosure;
58 class G1KlassScanClosure;
59 class ObjectClosure;
60 class SpaceClosure;
61 class CompactibleSpaceClosure;
62 class Space;
63 class G1CollectorPolicy;
64 class GenRemSet;
65 class G1RemSet;
66 class HeapRegionRemSetIterator;
67 class ConcurrentMark;
68 class ConcurrentMarkThread;
69 class ConcurrentG1Refine;
70 class ConcurrentGCTimer;
71 class GenerationCounters;
72 class STWGCTimer;
73 class G1NewTracer;
74 class G1OldTracer;
75 class EvacuationFailedInfo;
76 class nmethod;
77 class Ticks;
78
79 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue;
80 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
81
82 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
83 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
84
85 class YoungList : public CHeapObj<mtGC> {
86 private:
87 G1CollectedHeap* _g1h;
88
89 HeapRegion* _head;
90
91 HeapRegion* _survivor_head;
92 HeapRegion* _survivor_tail;
93
94 HeapRegion* _curr;
95
96 uint _length;
97 uint _survivor_length;
98
99 size_t _last_sampled_rs_lengths;
100 size_t _sampled_rs_lengths;
101
102 void empty_list(HeapRegion* list);
103
104 public:
105 YoungList(G1CollectedHeap* g1h);
106
107 void push_region(HeapRegion* hr);
108 void add_survivor_region(HeapRegion* hr);
109
110 void empty_list();
111 bool is_empty() { return _length == 0; }
112 uint length() { return _length; }
113 uint eden_length() { return length() - survivor_length(); }
114 uint survivor_length() { return _survivor_length; }
115
116 // Currently we do not keep track of the used byte sum for the
117 // young list and the survivors and it'd be quite a lot of work to
118 // do so. When we'll eventually replace the young list with
119 // instances of HeapRegionLinkedList we'll get that for free. So,
120 // we'll report the more accurate information then.
121 size_t eden_used_bytes() {
122 assert(length() >= survivor_length(), "invariant");
123 return (size_t) eden_length() * HeapRegion::GrainBytes;
124 }
125 size_t survivor_used_bytes() {
126 return (size_t) survivor_length() * HeapRegion::GrainBytes;
127 }
128
129 void rs_length_sampling_init();
130 bool rs_length_sampling_more();
131 void rs_length_sampling_next();
132
133 void reset_sampled_info() {
134 _last_sampled_rs_lengths = 0;
135 }
136 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }
137
138 // for development purposes
139 void reset_auxilary_lists();
140 void clear() { _head = NULL; _length = 0; }
141
142 void clear_survivors() {
143 _survivor_head = NULL;
144 _survivor_tail = NULL;
145 _survivor_length = 0;
146 }
147
148 HeapRegion* first_region() { return _head; }
149 HeapRegion* first_survivor_region() { return _survivor_head; }
150 HeapRegion* last_survivor_region() { return _survivor_tail; }
151
152 // debugging
153 bool check_list_well_formed();
154 bool check_list_empty(bool check_sample = true);
155 void print();
156 };
157
158 // The G1 STW is alive closure.
159 // An instance is embedded into the G1CH and used as the
160 // (optional) _is_alive_non_header closure in the STW
161 // reference processor. It is also extensively used during
162 // reference processing during STW evacuation pauses.
163 class G1STWIsAliveClosure: public BoolObjectClosure {
164 G1CollectedHeap* _g1;
165 public:
166 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
167 bool do_object_b(oop p);
168 };
169
170 class RefineCardTableEntryClosure;
171
172 class G1RegionMappingChangedListener : public G1MappingChangedListener {
173 private:
174 void reset_from_card_cache(uint start_idx, size_t num_regions);
175 public:
176 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
177 };
178
179 class G1CollectedHeap : public SharedHeap {
180 friend class VM_CollectForMetadataAllocation;
181 friend class VM_G1CollectForAllocation;
182 friend class VM_G1CollectFull;
183 friend class VM_G1IncCollectionPause;
184 friend class VMStructs;
185 friend class MutatorAllocRegion;
186 friend class SurvivorGCAllocRegion;
187 friend class OldGCAllocRegion;
188 friend class G1Allocator;
189
190 // Closures used in implementation.
191 friend class G1ParScanThreadState;
192 friend class G1ParTask;
193 friend class G1ParGCAllocator;
194 friend class G1PrepareCompactClosure;
195
196 // Other related classes.
197 friend class HeapRegionClaimer;
198
199 // Testing classes.
200 friend class G1CheckCSetFastTableClosure;
201
202 private:
203 // The one and only G1CollectedHeap, so static functions can find it.
204 static G1CollectedHeap* _g1h;
205
206 static size_t _humongous_object_threshold_in_words;
207
208 // The secondary free list which contains regions that have been
209 // freed up during the cleanup process. This will be appended to
210 // the master free list when appropriate.
211 FreeRegionList _secondary_free_list;
212
213 // It keeps track of the old regions.
214 HeapRegionSet _old_set;
215
216 // It keeps track of the humongous regions.
217 HeapRegionSet _humongous_set;
218
219 void eagerly_reclaim_humongous_regions();
220
221 // The number of regions we could create by expansion.
222 uint _expansion_regions;
223
224 // The block offset table for the G1 heap.
225 G1BlockOffsetSharedArray* _bot_shared;
226
227 // Tears down the region sets / lists so that they are empty and the
228 // regions on the heap do not belong to a region set / list. The
229 // only exception is the humongous set which we leave unaltered. If
230 // free_list_only is true, it will only tear down the master free
231 // list. It is called before a Full GC (free_list_only == false) or
232 // before heap shrinking (free_list_only == true).
233 void tear_down_region_sets(bool free_list_only);
234
235 // Rebuilds the region sets / lists so that they are repopulated to
236 // reflect the contents of the heap. The only exception is the
237 // humongous set which was not torn down in the first place. If
238 // free_list_only is true, it will only rebuild the master free
239 // list. It is called after a Full GC (free_list_only == false) or
240 // after heap shrinking (free_list_only == true).
241 void rebuild_region_sets(bool free_list_only);
242
243 // Callback for region mapping changed events.
244 G1RegionMappingChangedListener _listener;
245
246 // The sequence of all heap regions in the heap.
247 HeapRegionManager _hrm;
248
249 // Class that handles the different kinds of allocations.
250 G1Allocator* _allocator;
251
252 // Statistics for each allocation context
253 AllocationContextStats _allocation_context_stats;
254
255 // PLAB sizing policy for survivors.
256 PLABStats _survivor_plab_stats;
257
258 // PLAB sizing policy for tenured objects.
259 PLABStats _old_plab_stats;
260
261 // It specifies whether we should attempt to expand the heap after a
262 // region allocation failure. If heap expansion fails we set this to
263 // false so that we don't re-attempt the heap expansion (it's likely
264 // that subsequent expansion attempts will also fail if one fails).
265 // Currently, it is only consulted during GC and it's reset at the
266 // start of each GC.
267 bool _expand_heap_after_alloc_failure;
268
269 // It resets the mutator alloc region before new allocations can take place.
270 void init_mutator_alloc_region();
271
272 // It releases the mutator alloc region.
273 void release_mutator_alloc_region();
274
275 // It initializes the GC alloc regions at the start of a GC.
276 void init_gc_alloc_regions(EvacuationInfo& evacuation_info);
277
278 // It releases the GC alloc regions at the end of a GC.
279 void release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info);
280
281 // It does any cleanup that needs to be done on the GC alloc regions
282 // before a Full GC.
283 void abandon_gc_alloc_regions();
284
285 // Helper for monitoring and management support.
286 G1MonitoringSupport* _g1mm;
287
288 // Records whether the region at the given index is (still) a
289 // candidate for eager reclaim. Only valid for humongous start
290 // regions; other regions have unspecified values. Initialized at
291 // start of collection pause, with candidates removed as they are
292 // found reachable from roots or the young generation.
293 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> {
294 protected:
295 bool default_value() const { return false; }
296 public:
297 void clear() { G1BiasedMappedArray<bool>::clear(); }
298 void add_candidate(uint region) {
299 set_by_index(region, true);
300 }
301 void remove_candidate(uint region) {
302 set_by_index(region, false);
303 }
304 bool is_candidate(uint region) {
305 return get_by_index(region);
306 }
307 };
308
309 HumongousReclaimCandidates _humongous_reclaim_candidates;
310 // Stores whether during humongous object registration we found candidate regions.
311 // If not, we can skip a few steps.
312 bool _has_humongous_reclaim_candidates;
313
314 volatile unsigned _gc_time_stamp;
315
316 size_t* _surviving_young_words;
317
318 G1HRPrinter _hr_printer;
319
320 void setup_surviving_young_words();
321 void update_surviving_young_words(size_t* surv_young_words);
322 void cleanup_surviving_young_words();
323
324 // It decides whether an explicit GC should start a concurrent cycle
325 // instead of doing a STW GC. Currently, a concurrent cycle is
326 // explicitly started if:
327 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
328 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
329 // (c) cause == _g1_humongous_allocation
330 bool should_do_concurrent_full_gc(GCCause::Cause cause);
331
332 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
333 // concurrent cycles) we have started.
334 volatile uint _old_marking_cycles_started;
335
336 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
337 // concurrent cycles) we have completed.
338 volatile uint _old_marking_cycles_completed;
339
340 bool _concurrent_cycle_started;
341 bool _heap_summary_sent;
342
343 // This is a non-product method that is helpful for testing. It is
344 // called at the end of a GC and artificially expands the heap by
345 // allocating a number of dead regions. This way we can induce very
346 // frequent marking cycles and stress the cleanup / concurrent
347 // cleanup code more (as all the regions that will be allocated by
348 // this method will be found dead by the marking cycle).
349 void allocate_dummy_regions() PRODUCT_RETURN;
350
351 // Clear RSets after a compaction. It also resets the GC time stamps.
352 void clear_rsets_post_compaction();
353
354 // If the HR printer is active, dump the state of the regions in the
355 // heap after a compaction.
356 void print_hrm_post_compaction();
357
358 double verify(bool guard, const char* msg);
359 void verify_before_gc();
360 void verify_after_gc();
361
362 void log_gc_header();
363 void log_gc_footer(double pause_time_sec);
364
365 // These are macros so that, if the assert fires, we get the correct
366 // line number, file, etc.
367
368 #define heap_locking_asserts_err_msg(_extra_message_) \
369 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
370 (_extra_message_), \
371 BOOL_TO_STR(Heap_lock->owned_by_self()), \
372 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
373 BOOL_TO_STR(Thread::current()->is_VM_thread()))
374
375 #define assert_heap_locked() \
376 do { \
377 assert(Heap_lock->owned_by_self(), \
378 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
379 } while (0)
380
381 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
382 do { \
383 assert(Heap_lock->owned_by_self() || \
384 (SafepointSynchronize::is_at_safepoint() && \
385 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
386 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
387 "should be at a safepoint")); \
388 } while (0)
389
390 #define assert_heap_locked_and_not_at_safepoint() \
391 do { \
392 assert(Heap_lock->owned_by_self() && \
393 !SafepointSynchronize::is_at_safepoint(), \
394 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
395 "should not be at a safepoint")); \
396 } while (0)
397
398 #define assert_heap_not_locked() \
399 do { \
400 assert(!Heap_lock->owned_by_self(), \
401 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
402 } while (0)
403
404 #define assert_heap_not_locked_and_not_at_safepoint() \
405 do { \
406 assert(!Heap_lock->owned_by_self() && \
407 !SafepointSynchronize::is_at_safepoint(), \
408 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
409 "should not be at a safepoint")); \
410 } while (0)
411
412 #define assert_at_safepoint(_should_be_vm_thread_) \
413 do { \
414 assert(SafepointSynchronize::is_at_safepoint() && \
415 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
416 heap_locking_asserts_err_msg("should be at a safepoint")); \
417 } while (0)
418
419 #define assert_not_at_safepoint() \
420 do { \
421 assert(!SafepointSynchronize::is_at_safepoint(), \
422 heap_locking_asserts_err_msg("should not be at a safepoint")); \
423 } while (0)
424
425 protected:
426
427 // The young region list.
428 YoungList* _young_list;
429
430 // The current policy object for the collector.
431 G1CollectorPolicy* _g1_policy;
432
433 // This is the second level of trying to allocate a new region. If
434 // new_region() didn't find a region on the free_list, this call will
435 // check whether there's anything available on the
436 // secondary_free_list and/or wait for more regions to appear on
437 // that list, if _free_regions_coming is set.
438 HeapRegion* new_region_try_secondary_free_list(bool is_old);
439
440 // Try to allocate a single non-humongous HeapRegion sufficient for
441 // an allocation of the given word_size. If do_expand is true,
442 // attempt to expand the heap if necessary to satisfy the allocation
443 // request. If the region is to be used as an old region or for a
444 // humongous object, set is_old to true. If not, to false.
445 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand);
446
447 // Initialize a contiguous set of free regions of length num_regions
448 // and starting at index first so that they appear as a single
449 // humongous region.
450 HeapWord* humongous_obj_allocate_initialize_regions(uint first,
451 uint num_regions,
452 size_t word_size,
453 AllocationContext_t context);
454
455 // Attempt to allocate a humongous object of the given size. Return
456 // NULL if unsuccessful.
457 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context);
458
459 // The following two methods, allocate_new_tlab() and
460 // mem_allocate(), are the two main entry points from the runtime
461 // into the G1's allocation routines. They have the following
462 // assumptions:
463 //
464 // * They should both be called outside safepoints.
465 //
466 // * They should both be called without holding the Heap_lock.
467 //
468 // * All allocation requests for new TLABs should go to
469 // allocate_new_tlab().
470 //
471 // * All non-TLAB allocation requests should go to mem_allocate().
472 //
473 // * If either call cannot satisfy the allocation request using the
474 // current allocating region, they will try to get a new one. If
475 // this fails, they will attempt to do an evacuation pause and
476 // retry the allocation.
477 //
478 // * If all allocation attempts fail, even after trying to schedule
479 // an evacuation pause, allocate_new_tlab() will return NULL,
480 // whereas mem_allocate() will attempt a heap expansion and/or
481 // schedule a Full GC.
482 //
483 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
484 // should never be called with word_size being humongous. All
485 // humongous allocation requests should go to mem_allocate() which
486 // will satisfy them with a special path.
487
488 virtual HeapWord* allocate_new_tlab(size_t word_size);
489
490 virtual HeapWord* mem_allocate(size_t word_size,
491 bool* gc_overhead_limit_was_exceeded);
492
493 // The following three methods take a gc_count_before_ret
494 // parameter which is used to return the GC count if the method
495 // returns NULL. Given that we are required to read the GC count
496 // while holding the Heap_lock, and these paths will take the
497 // Heap_lock at some point, it's easier to get them to read the GC
498 // count while holding the Heap_lock before they return NULL instead
499 // of the caller (namely: mem_allocate()) having to also take the
500 // Heap_lock just to read the GC count.
501
502 // First-level mutator allocation attempt: try to allocate out of
503 // the mutator alloc region without taking the Heap_lock. This
504 // should only be used for non-humongous allocations.
505 inline HeapWord* attempt_allocation(size_t word_size,
506 uint* gc_count_before_ret,
507 uint* gclocker_retry_count_ret);
508
509 // Second-level mutator allocation attempt: take the Heap_lock and
510 // retry the allocation attempt, potentially scheduling a GC
511 // pause. This should only be used for non-humongous allocations.
512 HeapWord* attempt_allocation_slow(size_t word_size,
513 AllocationContext_t context,
514 uint* gc_count_before_ret,
515 uint* gclocker_retry_count_ret);
516
517 // Takes the Heap_lock and attempts a humongous allocation. It can
518 // potentially schedule a GC pause.
519 HeapWord* attempt_allocation_humongous(size_t word_size,
520 uint* gc_count_before_ret,
521 uint* gclocker_retry_count_ret);
522
523 // Allocation attempt that should be called during safepoints (e.g.,
524 // at the end of a successful GC). expect_null_mutator_alloc_region
525 // specifies whether the mutator alloc region is expected to be NULL
526 // or not.
527 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
528 AllocationContext_t context,
529 bool expect_null_mutator_alloc_region);
530
531 // It dirties the cards that cover the block so that so that the post
532 // write barrier never queues anything when updating objects on this
533 // block. It is assumed (and in fact we assert) that the block
534 // belongs to a young region.
535 inline void dirty_young_block(HeapWord* start, size_t word_size);
536
537 // Allocate blocks during garbage collection. Will ensure an
538 // allocation region, either by picking one or expanding the
539 // heap, and then allocate a block of the given size. The block
540 // may not be a humongous - it must fit into a single heap region.
541 inline HeapWord* par_allocate_during_gc(InCSetState dest,
542 size_t word_size,
543 AllocationContext_t context);
544 // Ensure that no further allocations can happen in "r", bearing in mind
545 // that parallel threads might be attempting allocations.
546 void par_allocate_remaining_space(HeapRegion* r);
547
548 // Allocation attempt during GC for a survivor object / PLAB.
549 inline HeapWord* survivor_attempt_allocation(size_t word_size,
550 AllocationContext_t context);
551
552 // Allocation attempt during GC for an old object / PLAB.
553 inline HeapWord* old_attempt_allocation(size_t word_size,
554 AllocationContext_t context);
555
556 // These methods are the "callbacks" from the G1AllocRegion class.
557
558 // For mutator alloc regions.
559 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
560 void retire_mutator_alloc_region(HeapRegion* alloc_region,
561 size_t allocated_bytes);
562
563 // For GC alloc regions.
564 HeapRegion* new_gc_alloc_region(size_t word_size, uint count,
565 InCSetState dest);
566 void retire_gc_alloc_region(HeapRegion* alloc_region,
567 size_t allocated_bytes, InCSetState dest);
568
569 // - if explicit_gc is true, the GC is for a System.gc() or a heap
570 // inspection request and should collect the entire heap
571 // - if clear_all_soft_refs is true, all soft references should be
572 // cleared during the GC
573 // - if explicit_gc is false, word_size describes the allocation that
574 // the GC should attempt (at least) to satisfy
575 // - it returns false if it is unable to do the collection due to the
576 // GC locker being active, true otherwise
577 bool do_collection(bool explicit_gc,
578 bool clear_all_soft_refs,
579 size_t word_size);
580
581 // Callback from VM_G1CollectFull operation.
582 // Perform a full collection.
583 virtual void do_full_collection(bool clear_all_soft_refs);
584
585 // Resize the heap if necessary after a full collection. If this is
586 // after a collect-for allocation, "word_size" is the allocation size,
587 // and will be considered part of the used portion of the heap.
588 void resize_if_necessary_after_full_collection(size_t word_size);
589
590 // Callback from VM_G1CollectForAllocation operation.
591 // This function does everything necessary/possible to satisfy a
592 // failed allocation request (including collection, expansion, etc.)
593 HeapWord* satisfy_failed_allocation(size_t word_size,
594 AllocationContext_t context,
595 bool* succeeded);
596
597 // Attempting to expand the heap sufficiently
598 // to support an allocation of the given "word_size". If
599 // successful, perform the allocation and return the address of the
600 // allocated block, or else "NULL".
601 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context);
602
603 // Process any reference objects discovered during
604 // an incremental evacuation pause.
605 void process_discovered_references(uint no_of_gc_workers);
606
607 // Enqueue any remaining discovered references
608 // after processing.
609 void enqueue_discovered_references(uint no_of_gc_workers);
610
611 public:
612
613 G1Allocator* allocator() {
614 return _allocator;
615 }
616
617 G1MonitoringSupport* g1mm() {
618 assert(_g1mm != NULL, "should have been initialized");
619 return _g1mm;
620 }
621
622 // Expand the garbage-first heap by at least the given size (in bytes!).
623 // Returns true if the heap was expanded by the requested amount;
624 // false otherwise.
625 // (Rounds up to a HeapRegion boundary.)
626 bool expand(size_t expand_bytes);
627
628 // Returns the PLAB statistics for a given destination.
629 inline PLABStats* alloc_buffer_stats(InCSetState dest);
630
631 // Determines PLAB size for a given destination.
632 inline size_t desired_plab_sz(InCSetState dest);
633
634 inline AllocationContextStats& allocation_context_stats();
635
636 // Do anything common to GC's.
637 virtual void gc_prologue(bool full);
638 virtual void gc_epilogue(bool full);
639
640 inline void set_humongous_is_live(oop obj);
641
642 void add_humongous_reclaim_candidate(uint region) {
643 assert(_hrm.at(region)->is_starts_humongous(), "Must start a humongous object");
644 _humongous_reclaim_candidates.add_candidate(region);
645 }
646
647 void remove_humongous_reclaim_candidate(uint region) {
648 assert(_hrm.at(region)->is_starts_humongous(), "Must start a humongous object");
649 _humongous_reclaim_candidates.remove_candidate(region);
650 }
651
652 bool is_humongous_reclaim_candidate(uint region) {
653 assert(_hrm.at(region)->is_starts_humongous(), "Must start a humongous object");
654 return _humongous_reclaim_candidates.is_candidate(region);
655 }
656
657 // Register the given region to be part of the collection set.
658 inline void register_humongous_region_with_cset(uint index);
659 // Register regions with humongous objects (actually on the start region) in
660 // the in_cset_fast_test table.
661 void register_humongous_regions_with_cset();
662 // We register a region with the fast "in collection set" test. We
663 // simply set to true the array slot corresponding to this region.
664 void register_young_region_with_cset(HeapRegion* r) {
665 _in_cset_fast_test.set_in_young(r->hrm_index());
666 }
667 void register_old_region_with_cset(HeapRegion* r) {
668 _in_cset_fast_test.set_in_old(r->hrm_index());
669 }
670 void clear_in_cset(const HeapRegion* hr) {
671 _in_cset_fast_test.clear(hr);
672 }
673
674 void clear_cset_fast_test() {
675 _in_cset_fast_test.clear();
676 }
677
678 // This is called at the start of either a concurrent cycle or a Full
679 // GC to update the number of old marking cycles started.
680 void increment_old_marking_cycles_started();
681
682 // This is called at the end of either a concurrent cycle or a Full
683 // GC to update the number of old marking cycles completed. Those two
684 // can happen in a nested fashion, i.e., we start a concurrent
685 // cycle, a Full GC happens half-way through it which ends first,
686 // and then the cycle notices that a Full GC happened and ends
687 // too. The concurrent parameter is a boolean to help us do a bit
688 // tighter consistency checking in the method. If concurrent is
689 // false, the caller is the inner caller in the nesting (i.e., the
690 // Full GC). If concurrent is true, the caller is the outer caller
691 // in this nesting (i.e., the concurrent cycle). Further nesting is
692 // not currently supported. The end of this call also notifies
693 // the FullGCCount_lock in case a Java thread is waiting for a full
694 // GC to happen (e.g., it called System.gc() with
695 // +ExplicitGCInvokesConcurrent).
696 void increment_old_marking_cycles_completed(bool concurrent);
697
698 uint old_marking_cycles_completed() {
699 return _old_marking_cycles_completed;
700 }
701
702 void register_concurrent_cycle_start(const Ticks& start_time);
703 void register_concurrent_cycle_end();
704 void trace_heap_after_concurrent_cycle();
705
706 G1YCType yc_type();
707
708 G1HRPrinter* hr_printer() { return &_hr_printer; }
709
710 // Frees a non-humongous region by initializing its contents and
711 // adding it to the free list that's passed as a parameter (this is
712 // usually a local list which will be appended to the master free
713 // list later). The used bytes of freed regions are accumulated in
714 // pre_used. If par is true, the region's RSet will not be freed
715 // up. The assumption is that this will be done later.
716 // The locked parameter indicates if the caller has already taken
717 // care of proper synchronization. This may allow some optimizations.
718 void free_region(HeapRegion* hr,
719 FreeRegionList* free_list,
720 bool par,
721 bool locked = false);
722
723 // Frees a humongous region by collapsing it into individual regions
724 // and calling free_region() for each of them. The freed regions
725 // will be added to the free list that's passed as a parameter (this
726 // is usually a local list which will be appended to the master free
727 // list later). The used bytes of freed regions are accumulated in
728 // pre_used. If par is true, the region's RSet will not be freed
729 // up. The assumption is that this will be done later.
730 void free_humongous_region(HeapRegion* hr,
731 FreeRegionList* free_list,
732 bool par);
733 protected:
734
735 // Shrink the garbage-first heap by at most the given size (in bytes!).
736 // (Rounds down to a HeapRegion boundary.)
737 virtual void shrink(size_t expand_bytes);
738 void shrink_helper(size_t expand_bytes);
739
740 #if TASKQUEUE_STATS
741 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
742 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
743 void reset_taskqueue_stats();
744 #endif // TASKQUEUE_STATS
745
746 // Schedule the VM operation that will do an evacuation pause to
747 // satisfy an allocation request of word_size. *succeeded will
748 // return whether the VM operation was successful (it did do an
749 // evacuation pause) or not (another thread beat us to it or the GC
750 // locker was active). Given that we should not be holding the
751 // Heap_lock when we enter this method, we will pass the
752 // gc_count_before (i.e., total_collections()) as a parameter since
753 // it has to be read while holding the Heap_lock. Currently, both
754 // methods that call do_collection_pause() release the Heap_lock
755 // before the call, so it's easy to read gc_count_before just before.
756 HeapWord* do_collection_pause(size_t word_size,
757 uint gc_count_before,
758 bool* succeeded,
759 GCCause::Cause gc_cause);
760
761 // The guts of the incremental collection pause, executed by the vm
762 // thread. It returns false if it is unable to do the collection due
763 // to the GC locker being active, true otherwise
764 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
765
766 // Actually do the work of evacuating the collection set.
767 void evacuate_collection_set(EvacuationInfo& evacuation_info);
768
769 // The g1 remembered set of the heap.
770 G1RemSet* _g1_rem_set;
771
772 // A set of cards that cover the objects for which the Rsets should be updated
773 // concurrently after the collection.
774 DirtyCardQueueSet _dirty_card_queue_set;
775
776 // The closure used to refine a single card.
777 RefineCardTableEntryClosure* _refine_cte_cl;
778
779 // A DirtyCardQueueSet that is used to hold cards that contain
780 // references into the current collection set. This is used to
781 // update the remembered sets of the regions in the collection
782 // set in the event of an evacuation failure.
783 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
784
785 // After a collection pause, make the regions in the CS into free
786 // regions.
787 void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info);
788
789 // Abandon the current collection set without recording policy
790 // statistics or updating free lists.
791 void abandon_collection_set(HeapRegion* cs_head);
792
793 // Applies "scan_non_heap_roots" to roots outside the heap,
794 // "scan_rs" to roots inside the heap (having done "set_region" to
795 // indicate the region in which the root resides),
796 // and does "scan_metadata" If "scan_rs" is
797 // NULL, then this step is skipped. The "worker_i"
798 // param is for use with parallel roots processing, and should be
799 // the "i" of the calling parallel worker thread's work(i) function.
800 // In the sequential case this param will be ignored.
801 void g1_process_roots(OopClosure* scan_non_heap_roots,
802 OopClosure* scan_non_heap_weak_roots,
803 G1ParPushHeapRSClosure* scan_rs,
804 CLDClosure* scan_strong_clds,
805 CLDClosure* scan_weak_clds,
806 CodeBlobClosure* scan_strong_code,
807 uint worker_i);
808
809 // The concurrent marker (and the thread it runs in.)
810 ConcurrentMark* _cm;
811 ConcurrentMarkThread* _cmThread;
812 bool _mark_in_progress;
813
814 // The concurrent refiner.
815 ConcurrentG1Refine* _cg1r;
816
817 // The parallel task queues
818 RefToScanQueueSet *_task_queues;
819
820 // True iff a evacuation has failed in the current collection.
821 bool _evacuation_failed;
822
823 EvacuationFailedInfo* _evacuation_failed_info_array;
824
825 // Failed evacuations cause some logical from-space objects to have
826 // forwarding pointers to themselves. Reset them.
827 void remove_self_forwarding_pointers();
828
829 // Together, these store an object with a preserved mark, and its mark value.
830 Stack<oop, mtGC> _objs_with_preserved_marks;
831 Stack<markOop, mtGC> _preserved_marks_of_objs;
832
833 // Preserve the mark of "obj", if necessary, in preparation for its mark
834 // word being overwritten with a self-forwarding-pointer.
835 void preserve_mark_if_necessary(oop obj, markOop m);
836
837 // The stack of evac-failure objects left to be scanned.
838 GrowableArray<oop>* _evac_failure_scan_stack;
839 // The closure to apply to evac-failure objects.
840
841 OopsInHeapRegionClosure* _evac_failure_closure;
842 // Set the field above.
843 void
844 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
845 _evac_failure_closure = evac_failure_closure;
846 }
847
848 // Push "obj" on the scan stack.
849 void push_on_evac_failure_scan_stack(oop obj);
850 // Process scan stack entries until the stack is empty.
851 void drain_evac_failure_scan_stack();
852 // True iff an invocation of "drain_scan_stack" is in progress; to
853 // prevent unnecessary recursion.
854 bool _drain_in_progress;
855
856 // Do any necessary initialization for evacuation-failure handling.
857 // "cl" is the closure that will be used to process evac-failure
858 // objects.
859 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
860 // Do any necessary cleanup for evacuation-failure handling data
861 // structures.
862 void finalize_for_evac_failure();
863
864 // An attempt to evacuate "obj" has failed; take necessary steps.
865 oop handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, oop obj);
866 void handle_evacuation_failure_common(oop obj, markOop m);
867
868 #ifndef PRODUCT
869 // Support for forcing evacuation failures. Analogous to
870 // PromotionFailureALot for the other collectors.
871
872 // Records whether G1EvacuationFailureALot should be in effect
873 // for the current GC
874 bool _evacuation_failure_alot_for_current_gc;
875
876 // Used to record the GC number for interval checking when
877 // determining whether G1EvaucationFailureALot is in effect
878 // for the current GC.
879 size_t _evacuation_failure_alot_gc_number;
880
881 // Count of the number of evacuations between failures.
882 volatile size_t _evacuation_failure_alot_count;
883
884 // Set whether G1EvacuationFailureALot should be in effect
885 // for the current GC (based upon the type of GC and which
886 // command line flags are set);
887 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young,
888 bool during_initial_mark,
889 bool during_marking);
890
891 inline void set_evacuation_failure_alot_for_current_gc();
892
893 // Return true if it's time to cause an evacuation failure.
894 inline bool evacuation_should_fail();
895
896 // Reset the G1EvacuationFailureALot counters. Should be called at
897 // the end of an evacuation pause in which an evacuation failure occurred.
898 inline void reset_evacuation_should_fail();
899 #endif // !PRODUCT
900
901 // ("Weak") Reference processing support.
902 //
903 // G1 has 2 instances of the reference processor class. One
904 // (_ref_processor_cm) handles reference object discovery
905 // and subsequent processing during concurrent marking cycles.
906 //
907 // The other (_ref_processor_stw) handles reference object
908 // discovery and processing during full GCs and incremental
909 // evacuation pauses.
910 //
911 // During an incremental pause, reference discovery will be
912 // temporarily disabled for _ref_processor_cm and will be
913 // enabled for _ref_processor_stw. At the end of the evacuation
914 // pause references discovered by _ref_processor_stw will be
915 // processed and discovery will be disabled. The previous
916 // setting for reference object discovery for _ref_processor_cm
917 // will be re-instated.
918 //
919 // At the start of marking:
920 // * Discovery by the CM ref processor is verified to be inactive
921 // and it's discovered lists are empty.
922 // * Discovery by the CM ref processor is then enabled.
923 //
924 // At the end of marking:
925 // * Any references on the CM ref processor's discovered
926 // lists are processed (possibly MT).
927 //
928 // At the start of full GC we:
929 // * Disable discovery by the CM ref processor and
930 // empty CM ref processor's discovered lists
931 // (without processing any entries).
932 // * Verify that the STW ref processor is inactive and it's
933 // discovered lists are empty.
934 // * Temporarily set STW ref processor discovery as single threaded.
935 // * Temporarily clear the STW ref processor's _is_alive_non_header
936 // field.
937 // * Finally enable discovery by the STW ref processor.
938 //
939 // The STW ref processor is used to record any discovered
940 // references during the full GC.
941 //
942 // At the end of a full GC we:
943 // * Enqueue any reference objects discovered by the STW ref processor
944 // that have non-live referents. This has the side-effect of
945 // making the STW ref processor inactive by disabling discovery.
946 // * Verify that the CM ref processor is still inactive
947 // and no references have been placed on it's discovered
948 // lists (also checked as a precondition during initial marking).
949
950 // The (stw) reference processor...
951 ReferenceProcessor* _ref_processor_stw;
952
953 STWGCTimer* _gc_timer_stw;
954 ConcurrentGCTimer* _gc_timer_cm;
955
956 G1OldTracer* _gc_tracer_cm;
957 G1NewTracer* _gc_tracer_stw;
958
959 // During reference object discovery, the _is_alive_non_header
960 // closure (if non-null) is applied to the referent object to
961 // determine whether the referent is live. If so then the
962 // reference object does not need to be 'discovered' and can
963 // be treated as a regular oop. This has the benefit of reducing
964 // the number of 'discovered' reference objects that need to
965 // be processed.
966 //
967 // Instance of the is_alive closure for embedding into the
968 // STW reference processor as the _is_alive_non_header field.
969 // Supplying a value for the _is_alive_non_header field is
970 // optional but doing so prevents unnecessary additions to
971 // the discovered lists during reference discovery.
972 G1STWIsAliveClosure _is_alive_closure_stw;
973
974 // The (concurrent marking) reference processor...
975 ReferenceProcessor* _ref_processor_cm;
976
977 // Instance of the concurrent mark is_alive closure for embedding
978 // into the Concurrent Marking reference processor as the
979 // _is_alive_non_header field. Supplying a value for the
980 // _is_alive_non_header field is optional but doing so prevents
981 // unnecessary additions to the discovered lists during reference
982 // discovery.
983 G1CMIsAliveClosure _is_alive_closure_cm;
984
985 // Cache used by G1CollectedHeap::start_cset_region_for_worker().
986 HeapRegion** _worker_cset_start_region;
987
988 // Time stamp to validate the regions recorded in the cache
989 // used by G1CollectedHeap::start_cset_region_for_worker().
990 // The heap region entry for a given worker is valid iff
991 // the associated time stamp value matches the current value
992 // of G1CollectedHeap::_gc_time_stamp.
993 uint* _worker_cset_start_region_time_stamp;
994
995 enum G1H_process_roots_tasks {
996 G1H_PS_filter_satb_buffers,
997 G1H_PS_refProcessor_oops_do,
998 // Leave this one last.
999 G1H_PS_NumElements
1000 };
1001
1002 SubTasksDone* _process_strong_tasks;
1003
1004 volatile bool _free_regions_coming;
1005
1006 public:
1007
1008 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
1009
1010 void set_refine_cte_cl_concurrency(bool concurrent);
1011
1012 RefToScanQueue *task_queue(int i) const;
1013
1014 // A set of cards where updates happened during the GC
1015 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
1016
1017 // A DirtyCardQueueSet that is used to hold cards that contain
1018 // references into the current collection set. This is used to
1019 // update the remembered sets of the regions in the collection
1020 // set in the event of an evacuation failure.
1021 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
1022 { return _into_cset_dirty_card_queue_set; }
1023
1024 // Create a G1CollectedHeap with the specified policy.
1025 // Must call the initialize method afterwards.
1026 // May not return if something goes wrong.
1027 G1CollectedHeap(G1CollectorPolicy* policy);
1028
1029 // Initialize the G1CollectedHeap to have the initial and
1030 // maximum sizes and remembered and barrier sets
1031 // specified by the policy object.
1032 jint initialize();
1033
1034 virtual void stop();
1035
1036 // Return the (conservative) maximum heap alignment for any G1 heap
1037 static size_t conservative_max_heap_alignment();
1038
1039 // Initialize weak reference processing.
1040 virtual void ref_processing_init();
1041
1042 void set_par_threads(uint t) {
1043 SharedHeap::set_par_threads(t);
1044 // Done in SharedHeap but oddly there are
1045 // two _process_strong_tasks's in a G1CollectedHeap
1046 // so do it here too.
1047 _process_strong_tasks->set_n_threads(t);
1048 }
1049
1050 // Set _n_par_threads according to a policy TBD.
1051 void set_par_threads();
1052
1053 void set_n_termination(int t) {
1054 _process_strong_tasks->set_n_threads(t);
1055 }
1056
1057 virtual CollectedHeap::Name kind() const {
1058 return CollectedHeap::G1CollectedHeap;
1059 }
1060
1061 // The current policy object for the collector.
1062 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
1063
1064 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); }
1065
1066 // Adaptive size policy. No such thing for g1.
1067 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
1068
1069 // The rem set and barrier set.
1070 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
1071
1072 unsigned get_gc_time_stamp() {
1073 return _gc_time_stamp;
1074 }
1075
1076 inline void reset_gc_time_stamp();
1077
1078 void check_gc_time_stamps() PRODUCT_RETURN;
1079
1080 inline void increment_gc_time_stamp();
1081
1082 // Reset the given region's GC timestamp. If it's starts humongous,
1083 // also reset the GC timestamp of its corresponding
1084 // continues humongous regions too.
1085 void reset_gc_time_stamps(HeapRegion* hr);
1086
1087 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
1088 DirtyCardQueue* into_cset_dcq,
1089 bool concurrent, uint worker_i);
1090
1091 // The shared block offset table array.
1092 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
1093
1094 // Reference Processing accessors
1095
1096 // The STW reference processor....
1097 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1098
1099 // The Concurrent Marking reference processor...
1100 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1101
1102 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; }
1103 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; }
1104
1105 virtual size_t capacity() const;
1106 virtual size_t used() const;
1107 // This should be called when we're not holding the heap lock. The
1108 // result might be a bit inaccurate.
1109 size_t used_unlocked() const;
1110 size_t recalculate_used() const;
1111
1112 // These virtual functions do the actual allocation.
1113 // Some heaps may offer a contiguous region for shared non-blocking
1114 // allocation, via inlined code (by exporting the address of the top and
1115 // end fields defining the extent of the contiguous allocation region.)
1116 // But G1CollectedHeap doesn't yet support this.
1117
1118 virtual bool is_maximal_no_gc() const {
1119 return _hrm.available() == 0;
1120 }
1121
1122 // The current number of regions in the heap.
1123 uint num_regions() const { return _hrm.length(); }
1124
1125 // The max number of regions in the heap.
1126 uint max_regions() const { return _hrm.max_length(); }
1127
1128 // The number of regions that are completely free.
1129 uint num_free_regions() const { return _hrm.num_free_regions(); }
1130
1131 MemoryUsage get_auxiliary_data_memory_usage() const {
1132 return _hrm.get_auxiliary_data_memory_usage();
1133 }
1134
1135 // The number of regions that are not completely free.
1136 uint num_used_regions() const { return num_regions() - num_free_regions(); }
1137
1138 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1139 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1140 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
1141 void verify_dirty_young_regions() PRODUCT_RETURN;
1142
1143 #ifndef PRODUCT
1144 // Make sure that the given bitmap has no marked objects in the
1145 // range [from,limit). If it does, print an error message and return
1146 // false. Otherwise, just return true. bitmap_name should be "prev"
1147 // or "next".
1148 bool verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
1149 HeapWord* from, HeapWord* limit);
1150
1151 // Verify that the prev / next bitmap range [tams,end) for the given
1152 // region has no marks. Return true if all is well, false if errors
1153 // are detected.
1154 bool verify_bitmaps(const char* caller, HeapRegion* hr);
1155 #endif // PRODUCT
1156
1157 // If G1VerifyBitmaps is set, verify that the marking bitmaps for
1158 // the given region do not have any spurious marks. If errors are
1159 // detected, print appropriate error messages and crash.
1160 void check_bitmaps(const char* caller, HeapRegion* hr) PRODUCT_RETURN;
1161
1162 // If G1VerifyBitmaps is set, verify that the marking bitmaps do not
1163 // have any spurious marks. If errors are detected, print
1164 // appropriate error messages and crash.
1165 void check_bitmaps(const char* caller) PRODUCT_RETURN;
1166
1167 // Do sanity check on the contents of the in-cset fast test table.
1168 bool check_cset_fast_test() PRODUCT_RETURN_( return true; );
1169
1170 // verify_region_sets() performs verification over the region
1171 // lists. It will be compiled in the product code to be used when
1172 // necessary (i.e., during heap verification).
1173 void verify_region_sets();
1174
1175 // verify_region_sets_optional() is planted in the code for
1176 // list verification in non-product builds (and it can be enabled in
1177 // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1).
1178 #if HEAP_REGION_SET_FORCE_VERIFY
1179 void verify_region_sets_optional() {
1180 verify_region_sets();
1181 }
1182 #else // HEAP_REGION_SET_FORCE_VERIFY
1183 void verify_region_sets_optional() { }
1184 #endif // HEAP_REGION_SET_FORCE_VERIFY
1185
1186 #ifdef ASSERT
1187 bool is_on_master_free_list(HeapRegion* hr) {
1188 return _hrm.is_free(hr);
1189 }
1190 #endif // ASSERT
1191
1192 // Wrapper for the region list operations that can be called from
1193 // methods outside this class.
1194
1195 void secondary_free_list_add(FreeRegionList* list) {
1196 _secondary_free_list.add_ordered(list);
1197 }
1198
1199 void append_secondary_free_list() {
1200 _hrm.insert_list_into_free_list(&_secondary_free_list);
1201 }
1202
1203 void append_secondary_free_list_if_not_empty_with_lock() {
1204 // If the secondary free list looks empty there's no reason to
1205 // take the lock and then try to append it.
1206 if (!_secondary_free_list.is_empty()) {
1207 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1208 append_secondary_free_list();
1209 }
1210 }
1211
1212 inline void old_set_remove(HeapRegion* hr);
1213
1214 size_t non_young_capacity_bytes() {
1215 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes();
1216 }
1217
1218 void set_free_regions_coming();
1219 void reset_free_regions_coming();
1220 bool free_regions_coming() { return _free_regions_coming; }
1221 void wait_while_free_regions_coming();
1222
1223 // Determine whether the given region is one that we are using as an
1224 // old GC alloc region.
1225 bool is_old_gc_alloc_region(HeapRegion* hr) {
1226 return _allocator->is_retained_old_region(hr);
1227 }
1228
1229 // Perform a collection of the heap; intended for use in implementing
1230 // "System.gc". This probably implies as full a collection as the
1231 // "CollectedHeap" supports.
1232 virtual void collect(GCCause::Cause cause);
1233
1234 // The same as above but assume that the caller holds the Heap_lock.
1235 void collect_locked(GCCause::Cause cause);
1236
1237 virtual bool copy_allocation_context_stats(const jint* contexts,
1238 jlong* totals,
1239 jbyte* accuracy,
1240 jint len);
1241
1242 // True iff an evacuation has failed in the most-recent collection.
1243 bool evacuation_failed() { return _evacuation_failed; }
1244
1245 void remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, const HeapRegionSetCount& humongous_regions_removed);
1246 void prepend_to_freelist(FreeRegionList* list);
1247 void decrement_summary_bytes(size_t bytes);
1248
1249 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1250 virtual bool is_in(const void* p) const;
1251 #ifdef ASSERT
1252 // Returns whether p is in one of the available areas of the heap. Slow but
1253 // extensive version.
1254 bool is_in_exact(const void* p) const;
1255 #endif
1256
1257 // Return "TRUE" iff the given object address is within the collection
1258 // set. Slow implementation.
1259 inline bool obj_in_cs(oop obj);
1260
1261 inline bool is_in_cset(const HeapRegion *hr);
1262 inline bool is_in_cset(oop obj);
1263
1264 inline bool is_in_cset_or_humongous(const oop obj);
1265
1266 private:
1267 // This array is used for a quick test on whether a reference points into
1268 // the collection set or not. Each of the array's elements denotes whether the
1269 // corresponding region is in the collection set or not.
1270 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test;
1271
1272 public:
1273
1274 inline InCSetState in_cset_state(const oop obj);
1275
1276 // Return "TRUE" iff the given object address is in the reserved
1277 // region of g1.
1278 bool is_in_g1_reserved(const void* p) const {
1279 return _hrm.reserved().contains(p);
1280 }
1281
1282 // Returns a MemRegion that corresponds to the space that has been
1283 // reserved for the heap
1284 MemRegion g1_reserved() const {
1285 return _hrm.reserved();
1286 }
1287
1288 virtual bool is_in_closed_subset(const void* p) const;
1289
1290 G1SATBCardTableLoggingModRefBS* g1_barrier_set() {
1291 return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set());
1292 }
1293
1294 // This resets the card table to all zeros. It is used after
1295 // a collection pause which used the card table to claim cards.
1296 void cleanUpCardTable();
1297
1298 // Iteration functions.
1299
1300 // Iterate over all the ref-containing fields of all objects, calling
1301 // "cl.do_oop" on each.
1302 virtual void oop_iterate(ExtendedOopClosure* cl);
1303
1304 // Iterate over all objects, calling "cl.do_object" on each.
1305 virtual void object_iterate(ObjectClosure* cl);
1306
1307 virtual void safe_object_iterate(ObjectClosure* cl) {
1308 object_iterate(cl);
1309 }
1310
1311 // Iterate over all spaces in use in the heap, in ascending address order.
1312 virtual void space_iterate(SpaceClosure* cl);
1313
1314 // Iterate over heap regions, in address order, terminating the
1315 // iteration early if the "doHeapRegion" method returns "true".
1316 void heap_region_iterate(HeapRegionClosure* blk) const;
1317
1318 // Return the region with the given index. It assumes the index is valid.
1319 inline HeapRegion* region_at(uint index) const;
1320
1321 // Calculate the region index of the given address. Given address must be
1322 // within the heap.
1323 inline uint addr_to_region(HeapWord* addr) const;
1324
1325 inline HeapWord* bottom_addr_for_region(uint index) const;
1326
1327 // Iterate over the heap regions in parallel. Assumes that this will be called
1328 // in parallel by ParallelGCThreads worker threads with distinct worker ids
1329 // in the range [0..max(ParallelGCThreads-1, 1)]. Applies "blk->doHeapRegion"
1330 // to each of the regions, by attempting to claim the region using the
1331 // HeapRegionClaimer and, if successful, applying the closure to the claimed
1332 // region. The concurrent argument should be set to true if iteration is
1333 // performed concurrently, during which no assumptions are made for consistent
1334 // attributes of the heap regions (as they might be modified while iterating).
1335 void heap_region_par_iterate(HeapRegionClosure* cl,
1336 uint worker_id,
1337 HeapRegionClaimer* hrclaimer,
1338 bool concurrent = false) const;
1339
1340 // Clear the cached cset start regions and (more importantly)
1341 // the time stamps. Called when we reset the GC time stamp.
1342 void clear_cset_start_regions();
1343
1344 // Given the id of a worker, obtain or calculate a suitable
1345 // starting region for iterating over the current collection set.
1346 HeapRegion* start_cset_region_for_worker(uint worker_i);
1347
1348 // Iterate over the regions (if any) in the current collection set.
1349 void collection_set_iterate(HeapRegionClosure* blk);
1350
1351 // As above but starting from region r
1352 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1353
1354 HeapRegion* next_compaction_region(const HeapRegion* from) const;
1355
1356 // A CollectedHeap will contain some number of spaces. This finds the
1357 // space containing a given address, or else returns NULL.
1358 virtual Space* space_containing(const void* addr) const;
1359
1360 // Returns the HeapRegion that contains addr. addr must not be NULL.
1361 template <class T>
1362 inline HeapRegion* heap_region_containing_raw(const T addr) const;
1363
1364 // Returns the HeapRegion that contains addr. addr must not be NULL.
1365 // If addr is within a humongous continues region, it returns its humongous start region.
1366 template <class T>
1367 inline HeapRegion* heap_region_containing(const T addr) const;
1368
1369 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1370 // each address in the (reserved) heap is a member of exactly
1371 // one block. The defining characteristic of a block is that it is
1372 // possible to find its size, and thus to progress forward to the next
1373 // block. (Blocks may be of different sizes.) Thus, blocks may
1374 // represent Java objects, or they might be free blocks in a
1375 // free-list-based heap (or subheap), as long as the two kinds are
1376 // distinguishable and the size of each is determinable.
1377
1378 // Returns the address of the start of the "block" that contains the
1379 // address "addr". We say "blocks" instead of "object" since some heaps
1380 // may not pack objects densely; a chunk may either be an object or a
1381 // non-object.
1382 virtual HeapWord* block_start(const void* addr) const;
1383
1384 // Requires "addr" to be the start of a chunk, and returns its size.
1385 // "addr + size" is required to be the start of a new chunk, or the end
1386 // of the active area of the heap.
1387 virtual size_t block_size(const HeapWord* addr) const;
1388
1389 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1390 // the block is an object.
1391 virtual bool block_is_obj(const HeapWord* addr) const;
1392
1393 // Does this heap support heap inspection? (+PrintClassHistogram)
1394 virtual bool supports_heap_inspection() const { return true; }
1395
1396 // Section on thread-local allocation buffers (TLABs)
1397 // See CollectedHeap for semantics.
1398
1399 bool supports_tlab_allocation() const;
1400 size_t tlab_capacity(Thread* ignored) const;
1401 size_t tlab_used(Thread* ignored) const;
1402 size_t max_tlab_size() const;
1403 size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1404
1405 // Can a compiler initialize a new object without store barriers?
1406 // This permission only extends from the creation of a new object
1407 // via a TLAB up to the first subsequent safepoint. If such permission
1408 // is granted for this heap type, the compiler promises to call
1409 // defer_store_barrier() below on any slow path allocation of
1410 // a new object for which such initializing store barriers will
1411 // have been elided. G1, like CMS, allows this, but should be
1412 // ready to provide a compensating write barrier as necessary
1413 // if that storage came out of a non-young region. The efficiency
1414 // of this implementation depends crucially on being able to
1415 // answer very efficiently in constant time whether a piece of
1416 // storage in the heap comes from a young region or not.
1417 // See ReduceInitialCardMarks.
1418 virtual bool can_elide_tlab_store_barriers() const {
1419 return true;
1420 }
1421
1422 virtual bool card_mark_must_follow_store() const {
1423 return true;
1424 }
1425
1426 inline bool is_in_young(const oop obj);
1427
1428 #ifdef ASSERT
1429 virtual bool is_in_partial_collection(const void* p);
1430 #endif
1431
1432 virtual bool is_scavengable(const void* addr);
1433
1434 // We don't need barriers for initializing stores to objects
1435 // in the young gen: for the SATB pre-barrier, there is no
1436 // pre-value that needs to be remembered; for the remembered-set
1437 // update logging post-barrier, we don't maintain remembered set
1438 // information for young gen objects.
1439 virtual inline bool can_elide_initializing_store_barrier(oop new_obj);
1440
1441 // Returns "true" iff the given word_size is "very large".
1442 static bool is_humongous(size_t word_size) {
1443 // Note this has to be strictly greater-than as the TLABs
1444 // are capped at the humongous threshold and we want to
1445 // ensure that we don't try to allocate a TLAB as
1446 // humongous and that we don't allocate a humongous
1447 // object in a TLAB.
1448 return word_size > _humongous_object_threshold_in_words;
1449 }
1450
1451 // Update mod union table with the set of dirty cards.
1452 void updateModUnion();
1453
1454 // Set the mod union bits corresponding to the given memRegion. Note
1455 // that this is always a safe operation, since it doesn't clear any
1456 // bits.
1457 void markModUnionRange(MemRegion mr);
1458
1459 // Records the fact that a marking phase is no longer in progress.
1460 void set_marking_complete() {
1461 _mark_in_progress = false;
1462 }
1463 void set_marking_started() {
1464 _mark_in_progress = true;
1465 }
1466 bool mark_in_progress() {
1467 return _mark_in_progress;
1468 }
1469
1470 // Print the maximum heap capacity.
1471 virtual size_t max_capacity() const;
1472
1473 virtual jlong millis_since_last_gc();
1474
1475
1476 // Convenience function to be used in situations where the heap type can be
1477 // asserted to be this type.
1478 static G1CollectedHeap* heap();
1479
1480 void set_region_short_lived_locked(HeapRegion* hr);
1481 // add appropriate methods for any other surv rate groups
1482
1483 YoungList* young_list() const { return _young_list; }
1484
1485 // debugging
1486 bool check_young_list_well_formed() {
1487 return _young_list->check_list_well_formed();
1488 }
1489
1490 bool check_young_list_empty(bool check_heap,
1491 bool check_sample = true);
1492
1493 // *** Stuff related to concurrent marking. It's not clear to me that so
1494 // many of these need to be public.
1495
1496 // The functions below are helper functions that a subclass of
1497 // "CollectedHeap" can use in the implementation of its virtual
1498 // functions.
1499 // This performs a concurrent marking of the live objects in a
1500 // bitmap off to the side.
1501 void doConcurrentMark();
1502
1503 bool isMarkedPrev(oop obj) const;
1504 bool isMarkedNext(oop obj) const;
1505
1506 // Determine if an object is dead, given the object and also
1507 // the region to which the object belongs. An object is dead
1508 // iff a) it was not allocated since the last mark and b) it
1509 // is not marked.
1510 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1511 return
1512 !hr->obj_allocated_since_prev_marking(obj) &&
1513 !isMarkedPrev(obj);
1514 }
1515
1516 // This function returns true when an object has been
1517 // around since the previous marking and hasn't yet
1518 // been marked during this marking.
1519 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1520 return
1521 !hr->obj_allocated_since_next_marking(obj) &&
1522 !isMarkedNext(obj);
1523 }
1524
1525 // Determine if an object is dead, given only the object itself.
1526 // This will find the region to which the object belongs and
1527 // then call the region version of the same function.
1528
1529 // Added if it is NULL it isn't dead.
1530
1531 inline bool is_obj_dead(const oop obj) const;
1532
1533 inline bool is_obj_ill(const oop obj) const;
1534
1535 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo);
1536 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo);
1537 bool is_marked(oop obj, VerifyOption vo);
1538 const char* top_at_mark_start_str(VerifyOption vo);
1539
1540 ConcurrentMark* concurrent_mark() const { return _cm; }
1541
1542 // Refinement
1543
1544 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1545
1546 // The dirty cards region list is used to record a subset of regions
1547 // whose cards need clearing. The list if populated during the
1548 // remembered set scanning and drained during the card table
1549 // cleanup. Although the methods are reentrant, population/draining
1550 // phases must not overlap. For synchronization purposes the last
1551 // element on the list points to itself.
1552 HeapRegion* _dirty_cards_region_list;
1553 void push_dirty_cards_region(HeapRegion* hr);
1554 HeapRegion* pop_dirty_cards_region();
1555
1556 // Optimized nmethod scanning support routines
1557
1558 // Register the given nmethod with the G1 heap.
1559 virtual void register_nmethod(nmethod* nm);
1560
1561 // Unregister the given nmethod from the G1 heap.
1562 virtual void unregister_nmethod(nmethod* nm);
1563
1564 // Free up superfluous code root memory.
1565 void purge_code_root_memory();
1566
1567 // Rebuild the strong code root lists for each region
1568 // after a full GC.
1569 void rebuild_strong_code_roots();
1570
1571 // Delete entries for dead interned string and clean up unreferenced symbols
1572 // in symbol table, possibly in parallel.
1573 void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true);
1574
1575 // Parallel phase of unloading/cleaning after G1 concurrent mark.
1576 void parallel_cleaning(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool class_unloading_occurred);
1577
1578 // Redirty logged cards in the refinement queue.
1579 void redirty_logged_cards();
1580 // Verification
1581
1582 // The following is just to alert the verification code
1583 // that a full collection has occurred and that the
1584 // remembered sets are no longer up to date.
1585 bool _full_collection;
1586 void set_full_collection() { _full_collection = true;}
1587 void clear_full_collection() {_full_collection = false;}
1588 bool full_collection() {return _full_collection;}
1589
1590 // Perform any cleanup actions necessary before allowing a verification.
1591 virtual void prepare_for_verify();
1592
1593 // Perform verification.
1594
1595 // vo == UsePrevMarking -> use "prev" marking information,
1596 // vo == UseNextMarking -> use "next" marking information
1597 // vo == UseMarkWord -> use the mark word in the object header
1598 //
1599 // NOTE: Only the "prev" marking information is guaranteed to be
1600 // consistent most of the time, so most calls to this should use
1601 // vo == UsePrevMarking.
1602 // Currently, there is only one case where this is called with
1603 // vo == UseNextMarking, which is to verify the "next" marking
1604 // information at the end of remark.
1605 // Currently there is only one place where this is called with
1606 // vo == UseMarkWord, which is to verify the marking during a
1607 // full GC.
1608 void verify(bool silent, VerifyOption vo);
1609
1610 // Override; it uses the "prev" marking information
1611 virtual void verify(bool silent);
1612
1613 // The methods below are here for convenience and dispatch the
1614 // appropriate method depending on value of the given VerifyOption
1615 // parameter. The values for that parameter, and their meanings,
1616 // are the same as those above.
1617
1618 bool is_obj_dead_cond(const oop obj,
1619 const HeapRegion* hr,
1620 const VerifyOption vo) const;
1621
1622 bool is_obj_dead_cond(const oop obj,
1623 const VerifyOption vo) const;
1624
1625 // Printing
1626
1627 virtual void print_on(outputStream* st) const;
1628 virtual void print_extended_on(outputStream* st) const;
1629 virtual void print_on_error(outputStream* st) const;
1630
1631 virtual void print_gc_threads_on(outputStream* st) const;
1632 virtual void gc_threads_do(ThreadClosure* tc) const;
1633
1634 // Override
1635 void print_tracing_info() const;
1636
1637 // The following two methods are helpful for debugging RSet issues.
1638 void print_cset_rsets() PRODUCT_RETURN;
1639 void print_all_rsets() PRODUCT_RETURN;
1640
1641 public:
1642 size_t pending_card_num();
1643 size_t cards_scanned();
1644
1645 protected:
1646 size_t _max_heap_capacity;
1647 };
1648
1649 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP