Tue, 28 Aug 2012 15:20:08 -0700
7041879: G1: introduce stress testing parameter to cause frequent evacuation failures
Summary: Add the flags G1EvacuationFailureALot flag (and supporting flags) to force trigger evacuation failures. The support flags control how often to trigger an evacuation failure and during which types of evacuation pause. This functionality is analogous to that of PromotionFailureALot for the other collectors.
Reviewed-by: brutisso
1 /*
2 * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP
28 #include "gc_implementation/g1/concurrentMark.hpp"
29 #include "gc_implementation/g1/g1AllocRegion.hpp"
30 #include "gc_implementation/g1/g1HRPrinter.hpp"
31 #include "gc_implementation/g1/g1RemSet.hpp"
32 #include "gc_implementation/g1/g1MonitoringSupport.hpp"
33 #include "gc_implementation/g1/heapRegionSeq.hpp"
34 #include "gc_implementation/g1/heapRegionSets.hpp"
35 #include "gc_implementation/shared/hSpaceCounters.hpp"
36 #include "gc_implementation/shared/parGCAllocBuffer.hpp"
37 #include "memory/barrierSet.hpp"
38 #include "memory/memRegion.hpp"
39 #include "memory/sharedHeap.hpp"
41 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
42 // It uses the "Garbage First" heap organization and algorithm, which
43 // may combine concurrent marking with parallel, incremental compaction of
44 // heap subsets that will yield large amounts of garbage.
46 class HeapRegion;
47 class HRRSCleanupTask;
48 class PermanentGenerationSpec;
49 class GenerationSpec;
50 class OopsInHeapRegionClosure;
51 class G1ScanHeapEvacClosure;
52 class ObjectClosure;
53 class SpaceClosure;
54 class CompactibleSpaceClosure;
55 class Space;
56 class G1CollectorPolicy;
57 class GenRemSet;
58 class G1RemSet;
59 class HeapRegionRemSetIterator;
60 class ConcurrentMark;
61 class ConcurrentMarkThread;
62 class ConcurrentG1Refine;
63 class GenerationCounters;
65 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue;
66 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
68 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
69 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
71 enum GCAllocPurpose {
72 GCAllocForTenured,
73 GCAllocForSurvived,
74 GCAllocPurposeCount
75 };
77 class YoungList : public CHeapObj<mtGC> {
78 private:
79 G1CollectedHeap* _g1h;
81 HeapRegion* _head;
83 HeapRegion* _survivor_head;
84 HeapRegion* _survivor_tail;
86 HeapRegion* _curr;
88 uint _length;
89 uint _survivor_length;
91 size_t _last_sampled_rs_lengths;
92 size_t _sampled_rs_lengths;
94 void empty_list(HeapRegion* list);
96 public:
97 YoungList(G1CollectedHeap* g1h);
99 void push_region(HeapRegion* hr);
100 void add_survivor_region(HeapRegion* hr);
102 void empty_list();
103 bool is_empty() { return _length == 0; }
104 uint length() { return _length; }
105 uint survivor_length() { return _survivor_length; }
107 // Currently we do not keep track of the used byte sum for the
108 // young list and the survivors and it'd be quite a lot of work to
109 // do so. When we'll eventually replace the young list with
110 // instances of HeapRegionLinkedList we'll get that for free. So,
111 // we'll report the more accurate information then.
112 size_t eden_used_bytes() {
113 assert(length() >= survivor_length(), "invariant");
114 return (size_t) (length() - survivor_length()) * HeapRegion::GrainBytes;
115 }
116 size_t survivor_used_bytes() {
117 return (size_t) survivor_length() * HeapRegion::GrainBytes;
118 }
120 void rs_length_sampling_init();
121 bool rs_length_sampling_more();
122 void rs_length_sampling_next();
124 void reset_sampled_info() {
125 _last_sampled_rs_lengths = 0;
126 }
127 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }
129 // for development purposes
130 void reset_auxilary_lists();
131 void clear() { _head = NULL; _length = 0; }
133 void clear_survivors() {
134 _survivor_head = NULL;
135 _survivor_tail = NULL;
136 _survivor_length = 0;
137 }
139 HeapRegion* first_region() { return _head; }
140 HeapRegion* first_survivor_region() { return _survivor_head; }
141 HeapRegion* last_survivor_region() { return _survivor_tail; }
143 // debugging
144 bool check_list_well_formed();
145 bool check_list_empty(bool check_sample = true);
146 void print();
147 };
149 class MutatorAllocRegion : public G1AllocRegion {
150 protected:
151 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
152 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
153 public:
154 MutatorAllocRegion()
155 : G1AllocRegion("Mutator Alloc Region", false /* bot_updates */) { }
156 };
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 // refence processing during STW evacuation pauses.
163 class G1STWIsAliveClosure: public BoolObjectClosure {
164 G1CollectedHeap* _g1;
165 public:
166 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
167 void do_object(oop p) { assert(false, "Do not call."); }
168 bool do_object_b(oop p);
169 };
171 class SurvivorGCAllocRegion : public G1AllocRegion {
172 protected:
173 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
174 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
175 public:
176 SurvivorGCAllocRegion()
177 : G1AllocRegion("Survivor GC Alloc Region", false /* bot_updates */) { }
178 };
180 class OldGCAllocRegion : public G1AllocRegion {
181 protected:
182 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
183 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
184 public:
185 OldGCAllocRegion()
186 : G1AllocRegion("Old GC Alloc Region", true /* bot_updates */) { }
187 };
189 class RefineCardTableEntryClosure;
191 class G1CollectedHeap : public SharedHeap {
192 friend class VM_G1CollectForAllocation;
193 friend class VM_GenCollectForPermanentAllocation;
194 friend class VM_G1CollectFull;
195 friend class VM_G1IncCollectionPause;
196 friend class VMStructs;
197 friend class MutatorAllocRegion;
198 friend class SurvivorGCAllocRegion;
199 friend class OldGCAllocRegion;
201 // Closures used in implementation.
202 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
203 friend class G1ParCopyClosure;
204 friend class G1IsAliveClosure;
205 friend class G1EvacuateFollowersClosure;
206 friend class G1ParScanThreadState;
207 friend class G1ParScanClosureSuper;
208 friend class G1ParEvacuateFollowersClosure;
209 friend class G1ParTask;
210 friend class G1FreeGarbageRegionClosure;
211 friend class RefineCardTableEntryClosure;
212 friend class G1PrepareCompactClosure;
213 friend class RegionSorter;
214 friend class RegionResetter;
215 friend class CountRCClosure;
216 friend class EvacPopObjClosure;
217 friend class G1ParCleanupCTTask;
219 // Other related classes.
220 friend class G1MarkSweep;
222 private:
223 // The one and only G1CollectedHeap, so static functions can find it.
224 static G1CollectedHeap* _g1h;
226 static size_t _humongous_object_threshold_in_words;
228 // Storage for the G1 heap (excludes the permanent generation).
229 VirtualSpace _g1_storage;
230 MemRegion _g1_reserved;
232 // The part of _g1_storage that is currently committed.
233 MemRegion _g1_committed;
235 // The master free list. It will satisfy all new region allocations.
236 MasterFreeRegionList _free_list;
238 // The secondary free list which contains regions that have been
239 // freed up during the cleanup process. This will be appended to the
240 // master free list when appropriate.
241 SecondaryFreeRegionList _secondary_free_list;
243 // It keeps track of the old regions.
244 MasterOldRegionSet _old_set;
246 // It keeps track of the humongous regions.
247 MasterHumongousRegionSet _humongous_set;
249 // The number of regions we could create by expansion.
250 uint _expansion_regions;
252 // The block offset table for the G1 heap.
253 G1BlockOffsetSharedArray* _bot_shared;
255 // Tears down the region sets / lists so that they are empty and the
256 // regions on the heap do not belong to a region set / list. The
257 // only exception is the humongous set which we leave unaltered. If
258 // free_list_only is true, it will only tear down the master free
259 // list. It is called before a Full GC (free_list_only == false) or
260 // before heap shrinking (free_list_only == true).
261 void tear_down_region_sets(bool free_list_only);
263 // Rebuilds the region sets / lists so that they are repopulated to
264 // reflect the contents of the heap. The only exception is the
265 // humongous set which was not torn down in the first place. If
266 // free_list_only is true, it will only rebuild the master free
267 // list. It is called after a Full GC (free_list_only == false) or
268 // after heap shrinking (free_list_only == true).
269 void rebuild_region_sets(bool free_list_only);
271 // The sequence of all heap regions in the heap.
272 HeapRegionSeq _hrs;
274 // Alloc region used to satisfy mutator allocation requests.
275 MutatorAllocRegion _mutator_alloc_region;
277 // Alloc region used to satisfy allocation requests by the GC for
278 // survivor objects.
279 SurvivorGCAllocRegion _survivor_gc_alloc_region;
281 // PLAB sizing policy for survivors.
282 PLABStats _survivor_plab_stats;
284 // Alloc region used to satisfy allocation requests by the GC for
285 // old objects.
286 OldGCAllocRegion _old_gc_alloc_region;
288 // PLAB sizing policy for tenured objects.
289 PLABStats _old_plab_stats;
291 PLABStats* stats_for_purpose(GCAllocPurpose purpose) {
292 PLABStats* stats = NULL;
294 switch (purpose) {
295 case GCAllocForSurvived:
296 stats = &_survivor_plab_stats;
297 break;
298 case GCAllocForTenured:
299 stats = &_old_plab_stats;
300 break;
301 default:
302 assert(false, "unrecognized GCAllocPurpose");
303 }
305 return stats;
306 }
308 // The last old region we allocated to during the last GC.
309 // Typically, it is not full so we should re-use it during the next GC.
310 HeapRegion* _retained_old_gc_alloc_region;
312 // It specifies whether we should attempt to expand the heap after a
313 // region allocation failure. If heap expansion fails we set this to
314 // false so that we don't re-attempt the heap expansion (it's likely
315 // that subsequent expansion attempts will also fail if one fails).
316 // Currently, it is only consulted during GC and it's reset at the
317 // start of each GC.
318 bool _expand_heap_after_alloc_failure;
320 // It resets the mutator alloc region before new allocations can take place.
321 void init_mutator_alloc_region();
323 // It releases the mutator alloc region.
324 void release_mutator_alloc_region();
326 // It initializes the GC alloc regions at the start of a GC.
327 void init_gc_alloc_regions();
329 // It releases the GC alloc regions at the end of a GC.
330 void release_gc_alloc_regions();
332 // It does any cleanup that needs to be done on the GC alloc regions
333 // before a Full GC.
334 void abandon_gc_alloc_regions();
336 // Helper for monitoring and management support.
337 G1MonitoringSupport* _g1mm;
339 // Determines PLAB size for a particular allocation purpose.
340 size_t desired_plab_sz(GCAllocPurpose purpose);
342 // Outside of GC pauses, the number of bytes used in all regions other
343 // than the current allocation region.
344 size_t _summary_bytes_used;
346 // This is used for a quick test on whether a reference points into
347 // the collection set or not. Basically, we have an array, with one
348 // byte per region, and that byte denotes whether the corresponding
349 // region is in the collection set or not. The entry corresponding
350 // the bottom of the heap, i.e., region 0, is pointed to by
351 // _in_cset_fast_test_base. The _in_cset_fast_test field has been
352 // biased so that it actually points to address 0 of the address
353 // space, to make the test as fast as possible (we can simply shift
354 // the address to address into it, instead of having to subtract the
355 // bottom of the heap from the address before shifting it; basically
356 // it works in the same way the card table works).
357 bool* _in_cset_fast_test;
359 // The allocated array used for the fast test on whether a reference
360 // points into the collection set or not. This field is also used to
361 // free the array.
362 bool* _in_cset_fast_test_base;
364 // The length of the _in_cset_fast_test_base array.
365 uint _in_cset_fast_test_length;
367 volatile unsigned _gc_time_stamp;
369 size_t* _surviving_young_words;
371 G1HRPrinter _hr_printer;
373 void setup_surviving_young_words();
374 void update_surviving_young_words(size_t* surv_young_words);
375 void cleanup_surviving_young_words();
377 // It decides whether an explicit GC should start a concurrent cycle
378 // instead of doing a STW GC. Currently, a concurrent cycle is
379 // explicitly started if:
380 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
381 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
382 // (c) cause == _g1_humongous_allocation
383 bool should_do_concurrent_full_gc(GCCause::Cause cause);
385 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
386 // concurrent cycles) we have started.
387 volatile unsigned int _old_marking_cycles_started;
389 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
390 // concurrent cycles) we have completed.
391 volatile unsigned int _old_marking_cycles_completed;
393 // This is a non-product method that is helpful for testing. It is
394 // called at the end of a GC and artificially expands the heap by
395 // allocating a number of dead regions. This way we can induce very
396 // frequent marking cycles and stress the cleanup / concurrent
397 // cleanup code more (as all the regions that will be allocated by
398 // this method will be found dead by the marking cycle).
399 void allocate_dummy_regions() PRODUCT_RETURN;
401 // Clear RSets after a compaction. It also resets the GC time stamps.
402 void clear_rsets_post_compaction();
404 // If the HR printer is active, dump the state of the regions in the
405 // heap after a compaction.
406 void print_hrs_post_compaction();
408 double verify(bool guard, const char* msg);
409 void verify_before_gc();
410 void verify_after_gc();
412 // These are macros so that, if the assert fires, we get the correct
413 // line number, file, etc.
415 #define heap_locking_asserts_err_msg(_extra_message_) \
416 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
417 (_extra_message_), \
418 BOOL_TO_STR(Heap_lock->owned_by_self()), \
419 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
420 BOOL_TO_STR(Thread::current()->is_VM_thread()))
422 #define assert_heap_locked() \
423 do { \
424 assert(Heap_lock->owned_by_self(), \
425 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
426 } while (0)
428 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
429 do { \
430 assert(Heap_lock->owned_by_self() || \
431 (SafepointSynchronize::is_at_safepoint() && \
432 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
433 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
434 "should be at a safepoint")); \
435 } while (0)
437 #define assert_heap_locked_and_not_at_safepoint() \
438 do { \
439 assert(Heap_lock->owned_by_self() && \
440 !SafepointSynchronize::is_at_safepoint(), \
441 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
442 "should not be at a safepoint")); \
443 } while (0)
445 #define assert_heap_not_locked() \
446 do { \
447 assert(!Heap_lock->owned_by_self(), \
448 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
449 } while (0)
451 #define assert_heap_not_locked_and_not_at_safepoint() \
452 do { \
453 assert(!Heap_lock->owned_by_self() && \
454 !SafepointSynchronize::is_at_safepoint(), \
455 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
456 "should not be at a safepoint")); \
457 } while (0)
459 #define assert_at_safepoint(_should_be_vm_thread_) \
460 do { \
461 assert(SafepointSynchronize::is_at_safepoint() && \
462 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
463 heap_locking_asserts_err_msg("should be at a safepoint")); \
464 } while (0)
466 #define assert_not_at_safepoint() \
467 do { \
468 assert(!SafepointSynchronize::is_at_safepoint(), \
469 heap_locking_asserts_err_msg("should not be at a safepoint")); \
470 } while (0)
472 protected:
474 // The young region list.
475 YoungList* _young_list;
477 // The current policy object for the collector.
478 G1CollectorPolicy* _g1_policy;
480 // This is the second level of trying to allocate a new region. If
481 // new_region() didn't find a region on the free_list, this call will
482 // check whether there's anything available on the
483 // secondary_free_list and/or wait for more regions to appear on
484 // that list, if _free_regions_coming is set.
485 HeapRegion* new_region_try_secondary_free_list();
487 // Try to allocate a single non-humongous HeapRegion sufficient for
488 // an allocation of the given word_size. If do_expand is true,
489 // attempt to expand the heap if necessary to satisfy the allocation
490 // request.
491 HeapRegion* new_region(size_t word_size, bool do_expand);
493 // Attempt to satisfy a humongous allocation request of the given
494 // size by finding a contiguous set of free regions of num_regions
495 // length and remove them from the master free list. Return the
496 // index of the first region or G1_NULL_HRS_INDEX if the search
497 // was unsuccessful.
498 uint humongous_obj_allocate_find_first(uint num_regions,
499 size_t word_size);
501 // Initialize a contiguous set of free regions of length num_regions
502 // and starting at index first so that they appear as a single
503 // humongous region.
504 HeapWord* humongous_obj_allocate_initialize_regions(uint first,
505 uint num_regions,
506 size_t word_size);
508 // Attempt to allocate a humongous object of the given size. Return
509 // NULL if unsuccessful.
510 HeapWord* humongous_obj_allocate(size_t word_size);
512 // The following two methods, allocate_new_tlab() and
513 // mem_allocate(), are the two main entry points from the runtime
514 // into the G1's allocation routines. They have the following
515 // assumptions:
516 //
517 // * They should both be called outside safepoints.
518 //
519 // * They should both be called without holding the Heap_lock.
520 //
521 // * All allocation requests for new TLABs should go to
522 // allocate_new_tlab().
523 //
524 // * All non-TLAB allocation requests should go to mem_allocate().
525 //
526 // * If either call cannot satisfy the allocation request using the
527 // current allocating region, they will try to get a new one. If
528 // this fails, they will attempt to do an evacuation pause and
529 // retry the allocation.
530 //
531 // * If all allocation attempts fail, even after trying to schedule
532 // an evacuation pause, allocate_new_tlab() will return NULL,
533 // whereas mem_allocate() will attempt a heap expansion and/or
534 // schedule a Full GC.
535 //
536 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
537 // should never be called with word_size being humongous. All
538 // humongous allocation requests should go to mem_allocate() which
539 // will satisfy them with a special path.
541 virtual HeapWord* allocate_new_tlab(size_t word_size);
543 virtual HeapWord* mem_allocate(size_t word_size,
544 bool* gc_overhead_limit_was_exceeded);
546 // The following three methods take a gc_count_before_ret
547 // parameter which is used to return the GC count if the method
548 // returns NULL. Given that we are required to read the GC count
549 // while holding the Heap_lock, and these paths will take the
550 // Heap_lock at some point, it's easier to get them to read the GC
551 // count while holding the Heap_lock before they return NULL instead
552 // of the caller (namely: mem_allocate()) having to also take the
553 // Heap_lock just to read the GC count.
555 // First-level mutator allocation attempt: try to allocate out of
556 // the mutator alloc region without taking the Heap_lock. This
557 // should only be used for non-humongous allocations.
558 inline HeapWord* attempt_allocation(size_t word_size,
559 unsigned int* gc_count_before_ret);
561 // Second-level mutator allocation attempt: take the Heap_lock and
562 // retry the allocation attempt, potentially scheduling a GC
563 // pause. This should only be used for non-humongous allocations.
564 HeapWord* attempt_allocation_slow(size_t word_size,
565 unsigned int* gc_count_before_ret);
567 // Takes the Heap_lock and attempts a humongous allocation. It can
568 // potentially schedule a GC pause.
569 HeapWord* attempt_allocation_humongous(size_t word_size,
570 unsigned int* gc_count_before_ret);
572 // Allocation attempt that should be called during safepoints (e.g.,
573 // at the end of a successful GC). expect_null_mutator_alloc_region
574 // specifies whether the mutator alloc region is expected to be NULL
575 // or not.
576 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
577 bool expect_null_mutator_alloc_region);
579 // It dirties the cards that cover the block so that so that the post
580 // write barrier never queues anything when updating objects on this
581 // block. It is assumed (and in fact we assert) that the block
582 // belongs to a young region.
583 inline void dirty_young_block(HeapWord* start, size_t word_size);
585 // Allocate blocks during garbage collection. Will ensure an
586 // allocation region, either by picking one or expanding the
587 // heap, and then allocate a block of the given size. The block
588 // may not be a humongous - it must fit into a single heap region.
589 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size);
591 HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose,
592 HeapRegion* alloc_region,
593 bool par,
594 size_t word_size);
596 // Ensure that no further allocations can happen in "r", bearing in mind
597 // that parallel threads might be attempting allocations.
598 void par_allocate_remaining_space(HeapRegion* r);
600 // Allocation attempt during GC for a survivor object / PLAB.
601 inline HeapWord* survivor_attempt_allocation(size_t word_size);
603 // Allocation attempt during GC for an old object / PLAB.
604 inline HeapWord* old_attempt_allocation(size_t word_size);
606 // These methods are the "callbacks" from the G1AllocRegion class.
608 // For mutator alloc regions.
609 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
610 void retire_mutator_alloc_region(HeapRegion* alloc_region,
611 size_t allocated_bytes);
613 // For GC alloc regions.
614 HeapRegion* new_gc_alloc_region(size_t word_size, uint count,
615 GCAllocPurpose ap);
616 void retire_gc_alloc_region(HeapRegion* alloc_region,
617 size_t allocated_bytes, GCAllocPurpose ap);
619 // - if explicit_gc is true, the GC is for a System.gc() or a heap
620 // inspection request and should collect the entire heap
621 // - if clear_all_soft_refs is true, all soft references should be
622 // cleared during the GC
623 // - if explicit_gc is false, word_size describes the allocation that
624 // the GC should attempt (at least) to satisfy
625 // - it returns false if it is unable to do the collection due to the
626 // GC locker being active, true otherwise
627 bool do_collection(bool explicit_gc,
628 bool clear_all_soft_refs,
629 size_t word_size);
631 // Callback from VM_G1CollectFull operation.
632 // Perform a full collection.
633 void do_full_collection(bool clear_all_soft_refs);
635 // Resize the heap if necessary after a full collection. If this is
636 // after a collect-for allocation, "word_size" is the allocation size,
637 // and will be considered part of the used portion of the heap.
638 void resize_if_necessary_after_full_collection(size_t word_size);
640 // Callback from VM_G1CollectForAllocation operation.
641 // This function does everything necessary/possible to satisfy a
642 // failed allocation request (including collection, expansion, etc.)
643 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded);
645 // Attempting to expand the heap sufficiently
646 // to support an allocation of the given "word_size". If
647 // successful, perform the allocation and return the address of the
648 // allocated block, or else "NULL".
649 HeapWord* expand_and_allocate(size_t word_size);
651 // Process any reference objects discovered during
652 // an incremental evacuation pause.
653 void process_discovered_references();
655 // Enqueue any remaining discovered references
656 // after processing.
657 void enqueue_discovered_references();
659 public:
661 G1MonitoringSupport* g1mm() {
662 assert(_g1mm != NULL, "should have been initialized");
663 return _g1mm;
664 }
666 // Expand the garbage-first heap by at least the given size (in bytes!).
667 // Returns true if the heap was expanded by the requested amount;
668 // false otherwise.
669 // (Rounds up to a HeapRegion boundary.)
670 bool expand(size_t expand_bytes);
672 // Do anything common to GC's.
673 virtual void gc_prologue(bool full);
674 virtual void gc_epilogue(bool full);
676 // We register a region with the fast "in collection set" test. We
677 // simply set to true the array slot corresponding to this region.
678 void register_region_with_in_cset_fast_test(HeapRegion* r) {
679 assert(_in_cset_fast_test_base != NULL, "sanity");
680 assert(r->in_collection_set(), "invariant");
681 uint index = r->hrs_index();
682 assert(index < _in_cset_fast_test_length, "invariant");
683 assert(!_in_cset_fast_test_base[index], "invariant");
684 _in_cset_fast_test_base[index] = true;
685 }
687 // This is a fast test on whether a reference points into the
688 // collection set or not. It does not assume that the reference
689 // points into the heap; if it doesn't, it will return false.
690 bool in_cset_fast_test(oop obj) {
691 assert(_in_cset_fast_test != NULL, "sanity");
692 if (_g1_committed.contains((HeapWord*) obj)) {
693 // no need to subtract the bottom of the heap from obj,
694 // _in_cset_fast_test is biased
695 uintx index = (uintx) obj >> HeapRegion::LogOfHRGrainBytes;
696 bool ret = _in_cset_fast_test[index];
697 // let's make sure the result is consistent with what the slower
698 // test returns
699 assert( ret || !obj_in_cs(obj), "sanity");
700 assert(!ret || obj_in_cs(obj), "sanity");
701 return ret;
702 } else {
703 return false;
704 }
705 }
707 void clear_cset_fast_test() {
708 assert(_in_cset_fast_test_base != NULL, "sanity");
709 memset(_in_cset_fast_test_base, false,
710 (size_t) _in_cset_fast_test_length * sizeof(bool));
711 }
713 // This is called at the start of either a concurrent cycle or a Full
714 // GC to update the number of old marking cycles started.
715 void increment_old_marking_cycles_started();
717 // This is called at the end of either a concurrent cycle or a Full
718 // GC to update the number of old marking cycles completed. Those two
719 // can happen in a nested fashion, i.e., we start a concurrent
720 // cycle, a Full GC happens half-way through it which ends first,
721 // and then the cycle notices that a Full GC happened and ends
722 // too. The concurrent parameter is a boolean to help us do a bit
723 // tighter consistency checking in the method. If concurrent is
724 // false, the caller is the inner caller in the nesting (i.e., the
725 // Full GC). If concurrent is true, the caller is the outer caller
726 // in this nesting (i.e., the concurrent cycle). Further nesting is
727 // not currently supported. The end of this call also notifies
728 // the FullGCCount_lock in case a Java thread is waiting for a full
729 // GC to happen (e.g., it called System.gc() with
730 // +ExplicitGCInvokesConcurrent).
731 void increment_old_marking_cycles_completed(bool concurrent);
733 unsigned int old_marking_cycles_completed() {
734 return _old_marking_cycles_completed;
735 }
737 G1HRPrinter* hr_printer() { return &_hr_printer; }
739 protected:
741 // Shrink the garbage-first heap by at most the given size (in bytes!).
742 // (Rounds down to a HeapRegion boundary.)
743 virtual void shrink(size_t expand_bytes);
744 void shrink_helper(size_t expand_bytes);
746 #if TASKQUEUE_STATS
747 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
748 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
749 void reset_taskqueue_stats();
750 #endif // TASKQUEUE_STATS
752 // Schedule the VM operation that will do an evacuation pause to
753 // satisfy an allocation request of word_size. *succeeded will
754 // return whether the VM operation was successful (it did do an
755 // evacuation pause) or not (another thread beat us to it or the GC
756 // locker was active). Given that we should not be holding the
757 // Heap_lock when we enter this method, we will pass the
758 // gc_count_before (i.e., total_collections()) as a parameter since
759 // it has to be read while holding the Heap_lock. Currently, both
760 // methods that call do_collection_pause() release the Heap_lock
761 // before the call, so it's easy to read gc_count_before just before.
762 HeapWord* do_collection_pause(size_t word_size,
763 unsigned int gc_count_before,
764 bool* succeeded);
766 // The guts of the incremental collection pause, executed by the vm
767 // thread. It returns false if it is unable to do the collection due
768 // to the GC locker being active, true otherwise
769 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
771 // Actually do the work of evacuating the collection set.
772 void evacuate_collection_set();
774 // The g1 remembered set of the heap.
775 G1RemSet* _g1_rem_set;
776 // And it's mod ref barrier set, used to track updates for the above.
777 ModRefBarrierSet* _mr_bs;
779 // A set of cards that cover the objects for which the Rsets should be updated
780 // concurrently after the collection.
781 DirtyCardQueueSet _dirty_card_queue_set;
783 // The Heap Region Rem Set Iterator.
784 HeapRegionRemSetIterator** _rem_set_iterator;
786 // The closure used to refine a single card.
787 RefineCardTableEntryClosure* _refine_cte_cl;
789 // A function to check the consistency of dirty card logs.
790 void check_ct_logs_at_safepoint();
792 // A DirtyCardQueueSet that is used to hold cards that contain
793 // references into the current collection set. This is used to
794 // update the remembered sets of the regions in the collection
795 // set in the event of an evacuation failure.
796 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
798 // After a collection pause, make the regions in the CS into free
799 // regions.
800 void free_collection_set(HeapRegion* cs_head);
802 // Abandon the current collection set without recording policy
803 // statistics or updating free lists.
804 void abandon_collection_set(HeapRegion* cs_head);
806 // Applies "scan_non_heap_roots" to roots outside the heap,
807 // "scan_rs" to roots inside the heap (having done "set_region" to
808 // indicate the region in which the root resides), and does "scan_perm"
809 // (setting the generation to the perm generation.) If "scan_rs" is
810 // NULL, then this step is skipped. The "worker_i"
811 // param is for use with parallel roots processing, and should be
812 // the "i" of the calling parallel worker thread's work(i) function.
813 // In the sequential case this param will be ignored.
814 void g1_process_strong_roots(bool collecting_perm_gen,
815 ScanningOption so,
816 OopClosure* scan_non_heap_roots,
817 OopsInHeapRegionClosure* scan_rs,
818 OopsInGenClosure* scan_perm,
819 int worker_i);
821 // Apply "blk" to all the weak roots of the system. These include
822 // JNI weak roots, the code cache, system dictionary, symbol table,
823 // string table, and referents of reachable weak refs.
824 void g1_process_weak_roots(OopClosure* root_closure,
825 OopClosure* non_root_closure);
827 // Frees a non-humongous region by initializing its contents and
828 // adding it to the free list that's passed as a parameter (this is
829 // usually a local list which will be appended to the master free
830 // list later). The used bytes of freed regions are accumulated in
831 // pre_used. If par is true, the region's RSet will not be freed
832 // up. The assumption is that this will be done later.
833 void free_region(HeapRegion* hr,
834 size_t* pre_used,
835 FreeRegionList* free_list,
836 bool par);
838 // Frees a humongous region by collapsing it into individual regions
839 // and calling free_region() for each of them. The freed regions
840 // will be added to the free list that's passed as a parameter (this
841 // is usually a local list which will be appended to the master free
842 // list later). The used bytes of freed regions are accumulated in
843 // pre_used. If par is true, the region's RSet will not be freed
844 // up. The assumption is that this will be done later.
845 void free_humongous_region(HeapRegion* hr,
846 size_t* pre_used,
847 FreeRegionList* free_list,
848 HumongousRegionSet* humongous_proxy_set,
849 bool par);
851 // Notifies all the necessary spaces that the committed space has
852 // been updated (either expanded or shrunk). It should be called
853 // after _g1_storage is updated.
854 void update_committed_space(HeapWord* old_end, HeapWord* new_end);
856 // The concurrent marker (and the thread it runs in.)
857 ConcurrentMark* _cm;
858 ConcurrentMarkThread* _cmThread;
859 bool _mark_in_progress;
861 // The concurrent refiner.
862 ConcurrentG1Refine* _cg1r;
864 // The parallel task queues
865 RefToScanQueueSet *_task_queues;
867 // True iff a evacuation has failed in the current collection.
868 bool _evacuation_failed;
870 // Set the attribute indicating whether evacuation has failed in the
871 // current collection.
872 void set_evacuation_failed(bool b) { _evacuation_failed = b; }
874 // Failed evacuations cause some logical from-space objects to have
875 // forwarding pointers to themselves. Reset them.
876 void remove_self_forwarding_pointers();
878 // When one is non-null, so is the other. Together, they each pair is
879 // an object with a preserved mark, and its mark value.
880 GrowableArray<oop>* _objs_with_preserved_marks;
881 GrowableArray<markOop>* _preserved_marks_of_objs;
883 // Preserve the mark of "obj", if necessary, in preparation for its mark
884 // word being overwritten with a self-forwarding-pointer.
885 void preserve_mark_if_necessary(oop obj, markOop m);
887 // The stack of evac-failure objects left to be scanned.
888 GrowableArray<oop>* _evac_failure_scan_stack;
889 // The closure to apply to evac-failure objects.
891 OopsInHeapRegionClosure* _evac_failure_closure;
892 // Set the field above.
893 void
894 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
895 _evac_failure_closure = evac_failure_closure;
896 }
898 // Push "obj" on the scan stack.
899 void push_on_evac_failure_scan_stack(oop obj);
900 // Process scan stack entries until the stack is empty.
901 void drain_evac_failure_scan_stack();
902 // True iff an invocation of "drain_scan_stack" is in progress; to
903 // prevent unnecessary recursion.
904 bool _drain_in_progress;
906 // Do any necessary initialization for evacuation-failure handling.
907 // "cl" is the closure that will be used to process evac-failure
908 // objects.
909 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
910 // Do any necessary cleanup for evacuation-failure handling data
911 // structures.
912 void finalize_for_evac_failure();
914 // An attempt to evacuate "obj" has failed; take necessary steps.
915 oop handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, oop obj);
916 void handle_evacuation_failure_common(oop obj, markOop m);
918 #ifndef PRODUCT
919 // Support for forcing evacuation failures. Analogous to
920 // PromotionFailureALot for the other collectors.
922 // Records whether G1EvacuationFailureALot should be in effect
923 // for the current GC
924 bool _evacuation_failure_alot_for_current_gc;
926 // Used to record the GC number for interval checking when
927 // determining whether G1EvaucationFailureALot is in effect
928 // for the current GC.
929 size_t _evacuation_failure_alot_gc_number;
931 // Count of the number of evacuations between failures.
932 volatile size_t _evacuation_failure_alot_count;
934 // Set whether G1EvacuationFailureALot should be in effect
935 // for the current GC (based upon the type of GC and which
936 // command line flags are set);
937 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young,
938 bool during_initial_mark,
939 bool during_marking);
941 inline void set_evacuation_failure_alot_for_current_gc();
943 // Return true if it's time to cause an evacuation failure.
944 inline bool evacuation_should_fail();
946 // Reset the G1EvacuationFailureALot counters. Should be called at
947 // the end of an evacuation pause in which an evacuation failure ocurred.
948 inline void reset_evacuation_should_fail();
949 #endif // !PRODUCT
951 // ("Weak") Reference processing support.
952 //
953 // G1 has 2 instances of the referece processor class. One
954 // (_ref_processor_cm) handles reference object discovery
955 // and subsequent processing during concurrent marking cycles.
956 //
957 // The other (_ref_processor_stw) handles reference object
958 // discovery and processing during full GCs and incremental
959 // evacuation pauses.
960 //
961 // During an incremental pause, reference discovery will be
962 // temporarily disabled for _ref_processor_cm and will be
963 // enabled for _ref_processor_stw. At the end of the evacuation
964 // pause references discovered by _ref_processor_stw will be
965 // processed and discovery will be disabled. The previous
966 // setting for reference object discovery for _ref_processor_cm
967 // will be re-instated.
968 //
969 // At the start of marking:
970 // * Discovery by the CM ref processor is verified to be inactive
971 // and it's discovered lists are empty.
972 // * Discovery by the CM ref processor is then enabled.
973 //
974 // At the end of marking:
975 // * Any references on the CM ref processor's discovered
976 // lists are processed (possibly MT).
977 //
978 // At the start of full GC we:
979 // * Disable discovery by the CM ref processor and
980 // empty CM ref processor's discovered lists
981 // (without processing any entries).
982 // * Verify that the STW ref processor is inactive and it's
983 // discovered lists are empty.
984 // * Temporarily set STW ref processor discovery as single threaded.
985 // * Temporarily clear the STW ref processor's _is_alive_non_header
986 // field.
987 // * Finally enable discovery by the STW ref processor.
988 //
989 // The STW ref processor is used to record any discovered
990 // references during the full GC.
991 //
992 // At the end of a full GC we:
993 // * Enqueue any reference objects discovered by the STW ref processor
994 // that have non-live referents. This has the side-effect of
995 // making the STW ref processor inactive by disabling discovery.
996 // * Verify that the CM ref processor is still inactive
997 // and no references have been placed on it's discovered
998 // lists (also checked as a precondition during initial marking).
1000 // The (stw) reference processor...
1001 ReferenceProcessor* _ref_processor_stw;
1003 // During reference object discovery, the _is_alive_non_header
1004 // closure (if non-null) is applied to the referent object to
1005 // determine whether the referent is live. If so then the
1006 // reference object does not need to be 'discovered' and can
1007 // be treated as a regular oop. This has the benefit of reducing
1008 // the number of 'discovered' reference objects that need to
1009 // be processed.
1010 //
1011 // Instance of the is_alive closure for embedding into the
1012 // STW reference processor as the _is_alive_non_header field.
1013 // Supplying a value for the _is_alive_non_header field is
1014 // optional but doing so prevents unnecessary additions to
1015 // the discovered lists during reference discovery.
1016 G1STWIsAliveClosure _is_alive_closure_stw;
1018 // The (concurrent marking) reference processor...
1019 ReferenceProcessor* _ref_processor_cm;
1021 // Instance of the concurrent mark is_alive closure for embedding
1022 // into the Concurrent Marking reference processor as the
1023 // _is_alive_non_header field. Supplying a value for the
1024 // _is_alive_non_header field is optional but doing so prevents
1025 // unnecessary additions to the discovered lists during reference
1026 // discovery.
1027 G1CMIsAliveClosure _is_alive_closure_cm;
1029 // Cache used by G1CollectedHeap::start_cset_region_for_worker().
1030 HeapRegion** _worker_cset_start_region;
1032 // Time stamp to validate the regions recorded in the cache
1033 // used by G1CollectedHeap::start_cset_region_for_worker().
1034 // The heap region entry for a given worker is valid iff
1035 // the associated time stamp value matches the current value
1036 // of G1CollectedHeap::_gc_time_stamp.
1037 unsigned int* _worker_cset_start_region_time_stamp;
1039 enum G1H_process_strong_roots_tasks {
1040 G1H_PS_filter_satb_buffers,
1041 G1H_PS_refProcessor_oops_do,
1042 // Leave this one last.
1043 G1H_PS_NumElements
1044 };
1046 SubTasksDone* _process_strong_tasks;
1048 volatile bool _free_regions_coming;
1050 public:
1052 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
1054 void set_refine_cte_cl_concurrency(bool concurrent);
1056 RefToScanQueue *task_queue(int i) const;
1058 // A set of cards where updates happened during the GC
1059 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
1061 // A DirtyCardQueueSet that is used to hold cards that contain
1062 // references into the current collection set. This is used to
1063 // update the remembered sets of the regions in the collection
1064 // set in the event of an evacuation failure.
1065 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
1066 { return _into_cset_dirty_card_queue_set; }
1068 // Create a G1CollectedHeap with the specified policy.
1069 // Must call the initialize method afterwards.
1070 // May not return if something goes wrong.
1071 G1CollectedHeap(G1CollectorPolicy* policy);
1073 // Initialize the G1CollectedHeap to have the initial and
1074 // maximum sizes, permanent generation, and remembered and barrier sets
1075 // specified by the policy object.
1076 jint initialize();
1078 // Initialize weak reference processing.
1079 virtual void ref_processing_init();
1081 void set_par_threads(uint t) {
1082 SharedHeap::set_par_threads(t);
1083 // Done in SharedHeap but oddly there are
1084 // two _process_strong_tasks's in a G1CollectedHeap
1085 // so do it here too.
1086 _process_strong_tasks->set_n_threads(t);
1087 }
1089 // Set _n_par_threads according to a policy TBD.
1090 void set_par_threads();
1092 void set_n_termination(int t) {
1093 _process_strong_tasks->set_n_threads(t);
1094 }
1096 virtual CollectedHeap::Name kind() const {
1097 return CollectedHeap::G1CollectedHeap;
1098 }
1100 // The current policy object for the collector.
1101 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
1103 // Adaptive size policy. No such thing for g1.
1104 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
1106 // The rem set and barrier set.
1107 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
1108 ModRefBarrierSet* mr_bs() const { return _mr_bs; }
1110 // The rem set iterator.
1111 HeapRegionRemSetIterator* rem_set_iterator(int i) {
1112 return _rem_set_iterator[i];
1113 }
1115 HeapRegionRemSetIterator* rem_set_iterator() {
1116 return _rem_set_iterator[0];
1117 }
1119 unsigned get_gc_time_stamp() {
1120 return _gc_time_stamp;
1121 }
1123 void reset_gc_time_stamp() {
1124 _gc_time_stamp = 0;
1125 OrderAccess::fence();
1126 // Clear the cached CSet starting regions and time stamps.
1127 // Their validity is dependent on the GC timestamp.
1128 clear_cset_start_regions();
1129 }
1131 void check_gc_time_stamps() PRODUCT_RETURN;
1133 void increment_gc_time_stamp() {
1134 ++_gc_time_stamp;
1135 OrderAccess::fence();
1136 }
1138 // Reset the given region's GC timestamp. If it's starts humongous,
1139 // also reset the GC timestamp of its corresponding
1140 // continues humongous regions too.
1141 void reset_gc_time_stamps(HeapRegion* hr);
1143 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
1144 DirtyCardQueue* into_cset_dcq,
1145 bool concurrent, int worker_i);
1147 // The shared block offset table array.
1148 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
1150 // Reference Processing accessors
1152 // The STW reference processor....
1153 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1155 // The Concurent Marking reference processor...
1156 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1158 virtual size_t capacity() const;
1159 virtual size_t used() const;
1160 // This should be called when we're not holding the heap lock. The
1161 // result might be a bit inaccurate.
1162 size_t used_unlocked() const;
1163 size_t recalculate_used() const;
1165 // These virtual functions do the actual allocation.
1166 // Some heaps may offer a contiguous region for shared non-blocking
1167 // allocation, via inlined code (by exporting the address of the top and
1168 // end fields defining the extent of the contiguous allocation region.)
1169 // But G1CollectedHeap doesn't yet support this.
1171 // Return an estimate of the maximum allocation that could be performed
1172 // without triggering any collection or expansion activity. In a
1173 // generational collector, for example, this is probably the largest
1174 // allocation that could be supported (without expansion) in the youngest
1175 // generation. It is "unsafe" because no locks are taken; the result
1176 // should be treated as an approximation, not a guarantee, for use in
1177 // heuristic resizing decisions.
1178 virtual size_t unsafe_max_alloc();
1180 virtual bool is_maximal_no_gc() const {
1181 return _g1_storage.uncommitted_size() == 0;
1182 }
1184 // The total number of regions in the heap.
1185 uint n_regions() { return _hrs.length(); }
1187 // The max number of regions in the heap.
1188 uint max_regions() { return _hrs.max_length(); }
1190 // The number of regions that are completely free.
1191 uint free_regions() { return _free_list.length(); }
1193 // The number of regions that are not completely free.
1194 uint used_regions() { return n_regions() - free_regions(); }
1196 // The number of regions available for "regular" expansion.
1197 uint expansion_regions() { return _expansion_regions; }
1199 // Factory method for HeapRegion instances. It will return NULL if
1200 // the allocation fails.
1201 HeapRegion* new_heap_region(uint hrs_index, HeapWord* bottom);
1203 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1204 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1205 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
1206 void verify_dirty_young_regions() PRODUCT_RETURN;
1208 // verify_region_sets() performs verification over the region
1209 // lists. It will be compiled in the product code to be used when
1210 // necessary (i.e., during heap verification).
1211 void verify_region_sets();
1213 // verify_region_sets_optional() is planted in the code for
1214 // list verification in non-product builds (and it can be enabled in
1215 // product builds by definning HEAP_REGION_SET_FORCE_VERIFY to be 1).
1216 #if HEAP_REGION_SET_FORCE_VERIFY
1217 void verify_region_sets_optional() {
1218 verify_region_sets();
1219 }
1220 #else // HEAP_REGION_SET_FORCE_VERIFY
1221 void verify_region_sets_optional() { }
1222 #endif // HEAP_REGION_SET_FORCE_VERIFY
1224 #ifdef ASSERT
1225 bool is_on_master_free_list(HeapRegion* hr) {
1226 return hr->containing_set() == &_free_list;
1227 }
1229 bool is_in_humongous_set(HeapRegion* hr) {
1230 return hr->containing_set() == &_humongous_set;
1231 }
1232 #endif // ASSERT
1234 // Wrapper for the region list operations that can be called from
1235 // methods outside this class.
1237 void secondary_free_list_add_as_tail(FreeRegionList* list) {
1238 _secondary_free_list.add_as_tail(list);
1239 }
1241 void append_secondary_free_list() {
1242 _free_list.add_as_head(&_secondary_free_list);
1243 }
1245 void append_secondary_free_list_if_not_empty_with_lock() {
1246 // If the secondary free list looks empty there's no reason to
1247 // take the lock and then try to append it.
1248 if (!_secondary_free_list.is_empty()) {
1249 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1250 append_secondary_free_list();
1251 }
1252 }
1254 void old_set_remove(HeapRegion* hr) {
1255 _old_set.remove(hr);
1256 }
1258 size_t non_young_capacity_bytes() {
1259 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes();
1260 }
1262 void set_free_regions_coming();
1263 void reset_free_regions_coming();
1264 bool free_regions_coming() { return _free_regions_coming; }
1265 void wait_while_free_regions_coming();
1267 // Determine whether the given region is one that we are using as an
1268 // old GC alloc region.
1269 bool is_old_gc_alloc_region(HeapRegion* hr) {
1270 return hr == _retained_old_gc_alloc_region;
1271 }
1273 // Perform a collection of the heap; intended for use in implementing
1274 // "System.gc". This probably implies as full a collection as the
1275 // "CollectedHeap" supports.
1276 virtual void collect(GCCause::Cause cause);
1278 // The same as above but assume that the caller holds the Heap_lock.
1279 void collect_locked(GCCause::Cause cause);
1281 // This interface assumes that it's being called by the
1282 // vm thread. It collects the heap assuming that the
1283 // heap lock is already held and that we are executing in
1284 // the context of the vm thread.
1285 virtual void collect_as_vm_thread(GCCause::Cause cause);
1287 // True iff a evacuation has failed in the most-recent collection.
1288 bool evacuation_failed() { return _evacuation_failed; }
1290 // It will free a region if it has allocated objects in it that are
1291 // all dead. It calls either free_region() or
1292 // free_humongous_region() depending on the type of the region that
1293 // is passed to it.
1294 void free_region_if_empty(HeapRegion* hr,
1295 size_t* pre_used,
1296 FreeRegionList* free_list,
1297 OldRegionSet* old_proxy_set,
1298 HumongousRegionSet* humongous_proxy_set,
1299 HRRSCleanupTask* hrrs_cleanup_task,
1300 bool par);
1302 // It appends the free list to the master free list and updates the
1303 // master humongous list according to the contents of the proxy
1304 // list. It also adjusts the total used bytes according to pre_used
1305 // (if par is true, it will do so by taking the ParGCRareEvent_lock).
1306 void update_sets_after_freeing_regions(size_t pre_used,
1307 FreeRegionList* free_list,
1308 OldRegionSet* old_proxy_set,
1309 HumongousRegionSet* humongous_proxy_set,
1310 bool par);
1312 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1313 virtual bool is_in(const void* p) const;
1315 // Return "TRUE" iff the given object address is within the collection
1316 // set.
1317 inline bool obj_in_cs(oop obj);
1319 // Return "TRUE" iff the given object address is in the reserved
1320 // region of g1 (excluding the permanent generation).
1321 bool is_in_g1_reserved(const void* p) const {
1322 return _g1_reserved.contains(p);
1323 }
1325 // Returns a MemRegion that corresponds to the space that has been
1326 // reserved for the heap
1327 MemRegion g1_reserved() {
1328 return _g1_reserved;
1329 }
1331 // Returns a MemRegion that corresponds to the space that has been
1332 // committed in the heap
1333 MemRegion g1_committed() {
1334 return _g1_committed;
1335 }
1337 virtual bool is_in_closed_subset(const void* p) const;
1339 // This resets the card table to all zeros. It is used after
1340 // a collection pause which used the card table to claim cards.
1341 void cleanUpCardTable();
1343 // Iteration functions.
1345 // Iterate over all the ref-containing fields of all objects, calling
1346 // "cl.do_oop" on each.
1347 virtual void oop_iterate(OopClosure* cl) {
1348 oop_iterate(cl, true);
1349 }
1350 void oop_iterate(OopClosure* cl, bool do_perm);
1352 // Same as above, restricted to a memory region.
1353 virtual void oop_iterate(MemRegion mr, OopClosure* cl) {
1354 oop_iterate(mr, cl, true);
1355 }
1356 void oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm);
1358 // Iterate over all objects, calling "cl.do_object" on each.
1359 virtual void object_iterate(ObjectClosure* cl) {
1360 object_iterate(cl, true);
1361 }
1362 virtual void safe_object_iterate(ObjectClosure* cl) {
1363 object_iterate(cl, true);
1364 }
1365 void object_iterate(ObjectClosure* cl, bool do_perm);
1367 // Iterate over all objects allocated since the last collection, calling
1368 // "cl.do_object" on each. The heap must have been initialized properly
1369 // to support this function, or else this call will fail.
1370 virtual void object_iterate_since_last_GC(ObjectClosure* cl);
1372 // Iterate over all spaces in use in the heap, in ascending address order.
1373 virtual void space_iterate(SpaceClosure* cl);
1375 // Iterate over heap regions, in address order, terminating the
1376 // iteration early if the "doHeapRegion" method returns "true".
1377 void heap_region_iterate(HeapRegionClosure* blk) const;
1379 // Return the region with the given index. It assumes the index is valid.
1380 HeapRegion* region_at(uint index) const { return _hrs.at(index); }
1382 // Divide the heap region sequence into "chunks" of some size (the number
1383 // of regions divided by the number of parallel threads times some
1384 // overpartition factor, currently 4). Assumes that this will be called
1385 // in parallel by ParallelGCThreads worker threads with discinct worker
1386 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
1387 // calls will use the same "claim_value", and that that claim value is
1388 // different from the claim_value of any heap region before the start of
1389 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by
1390 // attempting to claim the first region in each chunk, and, if
1391 // successful, applying the closure to each region in the chunk (and
1392 // setting the claim value of the second and subsequent regions of the
1393 // chunk.) For now requires that "doHeapRegion" always returns "false",
1394 // i.e., that a closure never attempt to abort a traversal.
1395 void heap_region_par_iterate_chunked(HeapRegionClosure* blk,
1396 uint worker,
1397 uint no_of_par_workers,
1398 jint claim_value);
1400 // It resets all the region claim values to the default.
1401 void reset_heap_region_claim_values();
1403 // Resets the claim values of regions in the current
1404 // collection set to the default.
1405 void reset_cset_heap_region_claim_values();
1407 #ifdef ASSERT
1408 bool check_heap_region_claim_values(jint claim_value);
1410 // Same as the routine above but only checks regions in the
1411 // current collection set.
1412 bool check_cset_heap_region_claim_values(jint claim_value);
1413 #endif // ASSERT
1415 // Clear the cached cset start regions and (more importantly)
1416 // the time stamps. Called when we reset the GC time stamp.
1417 void clear_cset_start_regions();
1419 // Given the id of a worker, obtain or calculate a suitable
1420 // starting region for iterating over the current collection set.
1421 HeapRegion* start_cset_region_for_worker(int worker_i);
1423 // This is a convenience method that is used by the
1424 // HeapRegionIterator classes to calculate the starting region for
1425 // each worker so that they do not all start from the same region.
1426 HeapRegion* start_region_for_worker(uint worker_i, uint no_of_par_workers);
1428 // Iterate over the regions (if any) in the current collection set.
1429 void collection_set_iterate(HeapRegionClosure* blk);
1431 // As above but starting from region r
1432 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1434 // Returns the first (lowest address) compactible space in the heap.
1435 virtual CompactibleSpace* first_compactible_space();
1437 // A CollectedHeap will contain some number of spaces. This finds the
1438 // space containing a given address, or else returns NULL.
1439 virtual Space* space_containing(const void* addr) const;
1441 // A G1CollectedHeap will contain some number of heap regions. This
1442 // finds the region containing a given address, or else returns NULL.
1443 template <class T>
1444 inline HeapRegion* heap_region_containing(const T addr) const;
1446 // Like the above, but requires "addr" to be in the heap (to avoid a
1447 // null-check), and unlike the above, may return an continuing humongous
1448 // region.
1449 template <class T>
1450 inline HeapRegion* heap_region_containing_raw(const T addr) const;
1452 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1453 // each address in the (reserved) heap is a member of exactly
1454 // one block. The defining characteristic of a block is that it is
1455 // possible to find its size, and thus to progress forward to the next
1456 // block. (Blocks may be of different sizes.) Thus, blocks may
1457 // represent Java objects, or they might be free blocks in a
1458 // free-list-based heap (or subheap), as long as the two kinds are
1459 // distinguishable and the size of each is determinable.
1461 // Returns the address of the start of the "block" that contains the
1462 // address "addr". We say "blocks" instead of "object" since some heaps
1463 // may not pack objects densely; a chunk may either be an object or a
1464 // non-object.
1465 virtual HeapWord* block_start(const void* addr) const;
1467 // Requires "addr" to be the start of a chunk, and returns its size.
1468 // "addr + size" is required to be the start of a new chunk, or the end
1469 // of the active area of the heap.
1470 virtual size_t block_size(const HeapWord* addr) const;
1472 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1473 // the block is an object.
1474 virtual bool block_is_obj(const HeapWord* addr) const;
1476 // Does this heap support heap inspection? (+PrintClassHistogram)
1477 virtual bool supports_heap_inspection() const { return true; }
1479 // Section on thread-local allocation buffers (TLABs)
1480 // See CollectedHeap for semantics.
1482 virtual bool supports_tlab_allocation() const;
1483 virtual size_t tlab_capacity(Thread* thr) const;
1484 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
1486 // Can a compiler initialize a new object without store barriers?
1487 // This permission only extends from the creation of a new object
1488 // via a TLAB up to the first subsequent safepoint. If such permission
1489 // is granted for this heap type, the compiler promises to call
1490 // defer_store_barrier() below on any slow path allocation of
1491 // a new object for which such initializing store barriers will
1492 // have been elided. G1, like CMS, allows this, but should be
1493 // ready to provide a compensating write barrier as necessary
1494 // if that storage came out of a non-young region. The efficiency
1495 // of this implementation depends crucially on being able to
1496 // answer very efficiently in constant time whether a piece of
1497 // storage in the heap comes from a young region or not.
1498 // See ReduceInitialCardMarks.
1499 virtual bool can_elide_tlab_store_barriers() const {
1500 return true;
1501 }
1503 virtual bool card_mark_must_follow_store() const {
1504 return true;
1505 }
1507 bool is_in_young(const oop obj) {
1508 HeapRegion* hr = heap_region_containing(obj);
1509 return hr != NULL && hr->is_young();
1510 }
1512 #ifdef ASSERT
1513 virtual bool is_in_partial_collection(const void* p);
1514 #endif
1516 virtual bool is_scavengable(const void* addr);
1518 // We don't need barriers for initializing stores to objects
1519 // in the young gen: for the SATB pre-barrier, there is no
1520 // pre-value that needs to be remembered; for the remembered-set
1521 // update logging post-barrier, we don't maintain remembered set
1522 // information for young gen objects.
1523 virtual bool can_elide_initializing_store_barrier(oop new_obj) {
1524 return is_in_young(new_obj);
1525 }
1527 // Can a compiler elide a store barrier when it writes
1528 // a permanent oop into the heap? Applies when the compiler
1529 // is storing x to the heap, where x->is_perm() is true.
1530 virtual bool can_elide_permanent_oop_store_barriers() const {
1531 // At least until perm gen collection is also G1-ified, at
1532 // which point this should return false.
1533 return true;
1534 }
1536 // Returns "true" iff the given word_size is "very large".
1537 static bool isHumongous(size_t word_size) {
1538 // Note this has to be strictly greater-than as the TLABs
1539 // are capped at the humongous thresold and we want to
1540 // ensure that we don't try to allocate a TLAB as
1541 // humongous and that we don't allocate a humongous
1542 // object in a TLAB.
1543 return word_size > _humongous_object_threshold_in_words;
1544 }
1546 // Update mod union table with the set of dirty cards.
1547 void updateModUnion();
1549 // Set the mod union bits corresponding to the given memRegion. Note
1550 // that this is always a safe operation, since it doesn't clear any
1551 // bits.
1552 void markModUnionRange(MemRegion mr);
1554 // Records the fact that a marking phase is no longer in progress.
1555 void set_marking_complete() {
1556 _mark_in_progress = false;
1557 }
1558 void set_marking_started() {
1559 _mark_in_progress = true;
1560 }
1561 bool mark_in_progress() {
1562 return _mark_in_progress;
1563 }
1565 // Print the maximum heap capacity.
1566 virtual size_t max_capacity() const;
1568 virtual jlong millis_since_last_gc();
1570 // Perform any cleanup actions necessary before allowing a verification.
1571 virtual void prepare_for_verify();
1573 // Perform verification.
1575 // vo == UsePrevMarking -> use "prev" marking information,
1576 // vo == UseNextMarking -> use "next" marking information
1577 // vo == UseMarkWord -> use the mark word in the object header
1578 //
1579 // NOTE: Only the "prev" marking information is guaranteed to be
1580 // consistent most of the time, so most calls to this should use
1581 // vo == UsePrevMarking.
1582 // Currently, there is only one case where this is called with
1583 // vo == UseNextMarking, which is to verify the "next" marking
1584 // information at the end of remark.
1585 // Currently there is only one place where this is called with
1586 // vo == UseMarkWord, which is to verify the marking during a
1587 // full GC.
1588 void verify(bool silent, VerifyOption vo);
1590 // Override; it uses the "prev" marking information
1591 virtual void verify(bool silent);
1592 virtual void print_on(outputStream* st) const;
1593 virtual void print_extended_on(outputStream* st) const;
1595 virtual void print_gc_threads_on(outputStream* st) const;
1596 virtual void gc_threads_do(ThreadClosure* tc) const;
1598 // Override
1599 void print_tracing_info() const;
1601 // The following two methods are helpful for debugging RSet issues.
1602 void print_cset_rsets() PRODUCT_RETURN;
1603 void print_all_rsets() PRODUCT_RETURN;
1605 // Convenience function to be used in situations where the heap type can be
1606 // asserted to be this type.
1607 static G1CollectedHeap* heap();
1609 void set_region_short_lived_locked(HeapRegion* hr);
1610 // add appropriate methods for any other surv rate groups
1612 YoungList* young_list() { return _young_list; }
1614 // debugging
1615 bool check_young_list_well_formed() {
1616 return _young_list->check_list_well_formed();
1617 }
1619 bool check_young_list_empty(bool check_heap,
1620 bool check_sample = true);
1622 // *** Stuff related to concurrent marking. It's not clear to me that so
1623 // many of these need to be public.
1625 // The functions below are helper functions that a subclass of
1626 // "CollectedHeap" can use in the implementation of its virtual
1627 // functions.
1628 // This performs a concurrent marking of the live objects in a
1629 // bitmap off to the side.
1630 void doConcurrentMark();
1632 bool isMarkedPrev(oop obj) const;
1633 bool isMarkedNext(oop obj) const;
1635 // Determine if an object is dead, given the object and also
1636 // the region to which the object belongs. An object is dead
1637 // iff a) it was not allocated since the last mark and b) it
1638 // is not marked.
1640 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1641 return
1642 !hr->obj_allocated_since_prev_marking(obj) &&
1643 !isMarkedPrev(obj);
1644 }
1646 // This function returns true when an object has been
1647 // around since the previous marking and hasn't yet
1648 // been marked during this marking.
1650 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1651 return
1652 !hr->obj_allocated_since_next_marking(obj) &&
1653 !isMarkedNext(obj);
1654 }
1656 // Determine if an object is dead, given only the object itself.
1657 // This will find the region to which the object belongs and
1658 // then call the region version of the same function.
1660 // Added if it is in permanent gen it isn't dead.
1661 // Added if it is NULL it isn't dead.
1663 bool is_obj_dead(const oop obj) const {
1664 const HeapRegion* hr = heap_region_containing(obj);
1665 if (hr == NULL) {
1666 if (Universe::heap()->is_in_permanent(obj))
1667 return false;
1668 else if (obj == NULL) return false;
1669 else return true;
1670 }
1671 else return is_obj_dead(obj, hr);
1672 }
1674 bool is_obj_ill(const oop obj) const {
1675 const HeapRegion* hr = heap_region_containing(obj);
1676 if (hr == NULL) {
1677 if (Universe::heap()->is_in_permanent(obj))
1678 return false;
1679 else if (obj == NULL) return false;
1680 else return true;
1681 }
1682 else return is_obj_ill(obj, hr);
1683 }
1685 // The methods below are here for convenience and dispatch the
1686 // appropriate method depending on value of the given VerifyOption
1687 // parameter. The options for that parameter are:
1688 //
1689 // vo == UsePrevMarking -> use "prev" marking information,
1690 // vo == UseNextMarking -> use "next" marking information,
1691 // vo == UseMarkWord -> use mark word from object header
1693 bool is_obj_dead_cond(const oop obj,
1694 const HeapRegion* hr,
1695 const VerifyOption vo) const {
1696 switch (vo) {
1697 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
1698 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
1699 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
1700 default: ShouldNotReachHere();
1701 }
1702 return false; // keep some compilers happy
1703 }
1705 bool is_obj_dead_cond(const oop obj,
1706 const VerifyOption vo) const {
1707 switch (vo) {
1708 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
1709 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
1710 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
1711 default: ShouldNotReachHere();
1712 }
1713 return false; // keep some compilers happy
1714 }
1716 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo);
1717 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo);
1718 bool is_marked(oop obj, VerifyOption vo);
1719 const char* top_at_mark_start_str(VerifyOption vo);
1721 // The following is just to alert the verification code
1722 // that a full collection has occurred and that the
1723 // remembered sets are no longer up to date.
1724 bool _full_collection;
1725 void set_full_collection() { _full_collection = true;}
1726 void clear_full_collection() {_full_collection = false;}
1727 bool full_collection() {return _full_collection;}
1729 ConcurrentMark* concurrent_mark() const { return _cm; }
1730 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1732 // The dirty cards region list is used to record a subset of regions
1733 // whose cards need clearing. The list if populated during the
1734 // remembered set scanning and drained during the card table
1735 // cleanup. Although the methods are reentrant, population/draining
1736 // phases must not overlap. For synchronization purposes the last
1737 // element on the list points to itself.
1738 HeapRegion* _dirty_cards_region_list;
1739 void push_dirty_cards_region(HeapRegion* hr);
1740 HeapRegion* pop_dirty_cards_region();
1742 public:
1743 void stop_conc_gc_threads();
1745 size_t pending_card_num();
1746 size_t cards_scanned();
1748 protected:
1749 size_t _max_heap_capacity;
1750 };
1752 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
1753 private:
1754 bool _retired;
1756 public:
1757 G1ParGCAllocBuffer(size_t gclab_word_size);
1759 void set_buf(HeapWord* buf) {
1760 ParGCAllocBuffer::set_buf(buf);
1761 _retired = false;
1762 }
1764 void retire(bool end_of_gc, bool retain) {
1765 if (_retired)
1766 return;
1767 ParGCAllocBuffer::retire(end_of_gc, retain);
1768 _retired = true;
1769 }
1770 };
1772 class G1ParScanThreadState : public StackObj {
1773 protected:
1774 G1CollectedHeap* _g1h;
1775 RefToScanQueue* _refs;
1776 DirtyCardQueue _dcq;
1777 CardTableModRefBS* _ct_bs;
1778 G1RemSet* _g1_rem;
1780 G1ParGCAllocBuffer _surviving_alloc_buffer;
1781 G1ParGCAllocBuffer _tenured_alloc_buffer;
1782 G1ParGCAllocBuffer* _alloc_buffers[GCAllocPurposeCount];
1783 ageTable _age_table;
1785 size_t _alloc_buffer_waste;
1786 size_t _undo_waste;
1788 OopsInHeapRegionClosure* _evac_failure_cl;
1789 G1ParScanHeapEvacClosure* _evac_cl;
1790 G1ParScanPartialArrayClosure* _partial_scan_cl;
1792 int _hash_seed;
1793 uint _queue_num;
1795 size_t _term_attempts;
1797 double _start;
1798 double _start_strong_roots;
1799 double _strong_roots_time;
1800 double _start_term;
1801 double _term_time;
1803 // Map from young-age-index (0 == not young, 1 is youngest) to
1804 // surviving words. base is what we get back from the malloc call
1805 size_t* _surviving_young_words_base;
1806 // this points into the array, as we use the first few entries for padding
1807 size_t* _surviving_young_words;
1809 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t))
1811 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
1813 void add_to_undo_waste(size_t waste) { _undo_waste += waste; }
1815 DirtyCardQueue& dirty_card_queue() { return _dcq; }
1816 CardTableModRefBS* ctbs() { return _ct_bs; }
1818 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) {
1819 if (!from->is_survivor()) {
1820 _g1_rem->par_write_ref(from, p, tid);
1821 }
1822 }
1824 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) {
1825 // If the new value of the field points to the same region or
1826 // is the to-space, we don't need to include it in the Rset updates.
1827 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) {
1828 size_t card_index = ctbs()->index_for(p);
1829 // If the card hasn't been added to the buffer, do it.
1830 if (ctbs()->mark_card_deferred(card_index)) {
1831 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
1832 }
1833 }
1834 }
1836 public:
1837 G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num);
1839 ~G1ParScanThreadState() {
1840 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base, mtGC);
1841 }
1843 RefToScanQueue* refs() { return _refs; }
1844 ageTable* age_table() { return &_age_table; }
1846 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) {
1847 return _alloc_buffers[purpose];
1848 }
1850 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; }
1851 size_t undo_waste() const { return _undo_waste; }
1853 #ifdef ASSERT
1854 bool verify_ref(narrowOop* ref) const;
1855 bool verify_ref(oop* ref) const;
1856 bool verify_task(StarTask ref) const;
1857 #endif // ASSERT
1859 template <class T> void push_on_queue(T* ref) {
1860 assert(verify_ref(ref), "sanity");
1861 refs()->push(ref);
1862 }
1864 template <class T> void update_rs(HeapRegion* from, T* p, int tid) {
1865 if (G1DeferredRSUpdate) {
1866 deferred_rs_update(from, p, tid);
1867 } else {
1868 immediate_rs_update(from, p, tid);
1869 }
1870 }
1872 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
1873 HeapWord* obj = NULL;
1874 size_t gclab_word_size = _g1h->desired_plab_sz(purpose);
1875 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {
1876 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);
1877 add_to_alloc_buffer_waste(alloc_buf->words_remaining());
1878 alloc_buf->flush_stats_and_retire(_g1h->stats_for_purpose(purpose),
1879 false /* end_of_gc */,
1880 false /* retain */);
1882 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size);
1883 if (buf == NULL) return NULL; // Let caller handle allocation failure.
1884 // Otherwise.
1885 alloc_buf->set_word_size(gclab_word_size);
1886 alloc_buf->set_buf(buf);
1888 obj = alloc_buf->allocate(word_sz);
1889 assert(obj != NULL, "buffer was definitely big enough...");
1890 } else {
1891 obj = _g1h->par_allocate_during_gc(purpose, word_sz);
1892 }
1893 return obj;
1894 }
1896 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {
1897 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
1898 if (obj != NULL) return obj;
1899 return allocate_slow(purpose, word_sz);
1900 }
1902 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {
1903 if (alloc_buffer(purpose)->contains(obj)) {
1904 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1),
1905 "should contain whole object");
1906 alloc_buffer(purpose)->undo_allocation(obj, word_sz);
1907 } else {
1908 CollectedHeap::fill_with_object(obj, word_sz);
1909 add_to_undo_waste(word_sz);
1910 }
1911 }
1913 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {
1914 _evac_failure_cl = evac_failure_cl;
1915 }
1916 OopsInHeapRegionClosure* evac_failure_closure() {
1917 return _evac_failure_cl;
1918 }
1920 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) {
1921 _evac_cl = evac_cl;
1922 }
1924 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) {
1925 _partial_scan_cl = partial_scan_cl;
1926 }
1928 int* hash_seed() { return &_hash_seed; }
1929 uint queue_num() { return _queue_num; }
1931 size_t term_attempts() const { return _term_attempts; }
1932 void note_term_attempt() { _term_attempts++; }
1934 void start_strong_roots() {
1935 _start_strong_roots = os::elapsedTime();
1936 }
1937 void end_strong_roots() {
1938 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
1939 }
1940 double strong_roots_time() const { return _strong_roots_time; }
1942 void start_term_time() {
1943 note_term_attempt();
1944 _start_term = os::elapsedTime();
1945 }
1946 void end_term_time() {
1947 _term_time += (os::elapsedTime() - _start_term);
1948 }
1949 double term_time() const { return _term_time; }
1951 double elapsed_time() const {
1952 return os::elapsedTime() - _start;
1953 }
1955 static void
1956 print_termination_stats_hdr(outputStream* const st = gclog_or_tty);
1957 void
1958 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const;
1960 size_t* surviving_young_words() {
1961 // We add on to hide entry 0 which accumulates surviving words for
1962 // age -1 regions (i.e. non-young ones)
1963 return _surviving_young_words;
1964 }
1966 void retire_alloc_buffers() {
1967 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
1968 size_t waste = _alloc_buffers[ap]->words_remaining();
1969 add_to_alloc_buffer_waste(waste);
1970 _alloc_buffers[ap]->flush_stats_and_retire(_g1h->stats_for_purpose((GCAllocPurpose)ap),
1971 true /* end_of_gc */,
1972 false /* retain */);
1973 }
1974 }
1976 template <class T> void deal_with_reference(T* ref_to_scan) {
1977 if (has_partial_array_mask(ref_to_scan)) {
1978 _partial_scan_cl->do_oop_nv(ref_to_scan);
1979 } else {
1980 // Note: we can use "raw" versions of "region_containing" because
1981 // "obj_to_scan" is definitely in the heap, and is not in a
1982 // humongous region.
1983 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
1984 _evac_cl->set_region(r);
1985 _evac_cl->do_oop_nv(ref_to_scan);
1986 }
1987 }
1989 void deal_with_reference(StarTask ref) {
1990 assert(verify_task(ref), "sanity");
1991 if (ref.is_narrow()) {
1992 deal_with_reference((narrowOop*)ref);
1993 } else {
1994 deal_with_reference((oop*)ref);
1995 }
1996 }
1998 public:
1999 void trim_queue();
2000 };
2002 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP