Tue, 14 Jun 2011 11:01:10 -0700
7004681: G1: Extend marking verification to Full GCs
Summary: Perform a heap verification after the first phase of G1's full GC using objects' mark words to determine liveness. The third parameter of the heap verification routines, which was used in G1 to determine which marking bitmap to use in liveness calculations, has been changed from a boolean to an enum with values defined for using the mark word, and the 'prev' and 'next' bitmaps.
Reviewed-by: tonyp, ysr
1 /*
2 * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
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7 * published by the Free Software Foundation.
8 *
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
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23 */
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/g1RemSet.hpp"
31 #include "gc_implementation/g1/g1MonitoringSupport.hpp"
32 #include "gc_implementation/g1/heapRegionSeq.hpp"
33 #include "gc_implementation/g1/heapRegionSets.hpp"
34 #include "gc_implementation/shared/hSpaceCounters.hpp"
35 #include "gc_implementation/parNew/parGCAllocBuffer.hpp"
36 #include "memory/barrierSet.hpp"
37 #include "memory/memRegion.hpp"
38 #include "memory/sharedHeap.hpp"
40 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
41 // It uses the "Garbage First" heap organization and algorithm, which
42 // may combine concurrent marking with parallel, incremental compaction of
43 // heap subsets that will yield large amounts of garbage.
45 class HeapRegion;
46 class HRRSCleanupTask;
47 class PermanentGenerationSpec;
48 class GenerationSpec;
49 class OopsInHeapRegionClosure;
50 class G1ScanHeapEvacClosure;
51 class ObjectClosure;
52 class SpaceClosure;
53 class CompactibleSpaceClosure;
54 class Space;
55 class G1CollectorPolicy;
56 class GenRemSet;
57 class G1RemSet;
58 class HeapRegionRemSetIterator;
59 class ConcurrentMark;
60 class ConcurrentMarkThread;
61 class ConcurrentG1Refine;
62 class GenerationCounters;
64 typedef OverflowTaskQueue<StarTask> RefToScanQueue;
65 typedef GenericTaskQueueSet<RefToScanQueue> RefToScanQueueSet;
67 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
68 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
70 enum GCAllocPurpose {
71 GCAllocForTenured,
72 GCAllocForSurvived,
73 GCAllocPurposeCount
74 };
76 class YoungList : public CHeapObj {
77 private:
78 G1CollectedHeap* _g1h;
80 HeapRegion* _head;
82 HeapRegion* _survivor_head;
83 HeapRegion* _survivor_tail;
85 HeapRegion* _curr;
87 size_t _length;
88 size_t _survivor_length;
90 size_t _last_sampled_rs_lengths;
91 size_t _sampled_rs_lengths;
93 void empty_list(HeapRegion* list);
95 public:
96 YoungList(G1CollectedHeap* g1h);
98 void push_region(HeapRegion* hr);
99 void add_survivor_region(HeapRegion* hr);
101 void empty_list();
102 bool is_empty() { return _length == 0; }
103 size_t length() { return _length; }
104 size_t survivor_length() { return _survivor_length; }
106 // Currently we do not keep track of the used byte sum for the
107 // young list and the survivors and it'd be quite a lot of work to
108 // do so. When we'll eventually replace the young list with
109 // instances of HeapRegionLinkedList we'll get that for free. So,
110 // we'll report the more accurate information then.
111 size_t eden_used_bytes() {
112 assert(length() >= survivor_length(), "invariant");
113 return (length() - survivor_length()) * HeapRegion::GrainBytes;
114 }
115 size_t survivor_used_bytes() {
116 return survivor_length() * HeapRegion::GrainBytes;
117 }
119 void rs_length_sampling_init();
120 bool rs_length_sampling_more();
121 void rs_length_sampling_next();
123 void reset_sampled_info() {
124 _last_sampled_rs_lengths = 0;
125 }
126 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }
128 // for development purposes
129 void reset_auxilary_lists();
130 void clear() { _head = NULL; _length = 0; }
132 void clear_survivors() {
133 _survivor_head = NULL;
134 _survivor_tail = NULL;
135 _survivor_length = 0;
136 }
138 HeapRegion* first_region() { return _head; }
139 HeapRegion* first_survivor_region() { return _survivor_head; }
140 HeapRegion* last_survivor_region() { return _survivor_tail; }
142 // debugging
143 bool check_list_well_formed();
144 bool check_list_empty(bool check_sample = true);
145 void print();
146 };
148 class MutatorAllocRegion : public G1AllocRegion {
149 protected:
150 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
151 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
152 public:
153 MutatorAllocRegion()
154 : G1AllocRegion("Mutator Alloc Region", false /* bot_updates */) { }
155 };
157 class RefineCardTableEntryClosure;
158 class G1CollectedHeap : public SharedHeap {
159 friend class VM_G1CollectForAllocation;
160 friend class VM_GenCollectForPermanentAllocation;
161 friend class VM_G1CollectFull;
162 friend class VM_G1IncCollectionPause;
163 friend class VMStructs;
164 friend class MutatorAllocRegion;
166 // Closures used in implementation.
167 friend class G1ParCopyHelper;
168 friend class G1IsAliveClosure;
169 friend class G1EvacuateFollowersClosure;
170 friend class G1ParScanThreadState;
171 friend class G1ParScanClosureSuper;
172 friend class G1ParEvacuateFollowersClosure;
173 friend class G1ParTask;
174 friend class G1FreeGarbageRegionClosure;
175 friend class RefineCardTableEntryClosure;
176 friend class G1PrepareCompactClosure;
177 friend class RegionSorter;
178 friend class RegionResetter;
179 friend class CountRCClosure;
180 friend class EvacPopObjClosure;
181 friend class G1ParCleanupCTTask;
183 // Other related classes.
184 friend class G1MarkSweep;
186 private:
187 // The one and only G1CollectedHeap, so static functions can find it.
188 static G1CollectedHeap* _g1h;
190 static size_t _humongous_object_threshold_in_words;
192 // Storage for the G1 heap (excludes the permanent generation).
193 VirtualSpace _g1_storage;
194 MemRegion _g1_reserved;
196 // The part of _g1_storage that is currently committed.
197 MemRegion _g1_committed;
199 // The master free list. It will satisfy all new region allocations.
200 MasterFreeRegionList _free_list;
202 // The secondary free list which contains regions that have been
203 // freed up during the cleanup process. This will be appended to the
204 // master free list when appropriate.
205 SecondaryFreeRegionList _secondary_free_list;
207 // It keeps track of the humongous regions.
208 MasterHumongousRegionSet _humongous_set;
210 // The number of regions we could create by expansion.
211 size_t _expansion_regions;
213 // The block offset table for the G1 heap.
214 G1BlockOffsetSharedArray* _bot_shared;
216 // Move all of the regions off the free lists, then rebuild those free
217 // lists, before and after full GC.
218 void tear_down_region_lists();
219 void rebuild_region_lists();
221 // The sequence of all heap regions in the heap.
222 HeapRegionSeq _hrs;
224 // Alloc region used to satisfy mutator allocation requests.
225 MutatorAllocRegion _mutator_alloc_region;
227 // It resets the mutator alloc region before new allocations can take place.
228 void init_mutator_alloc_region();
230 // It releases the mutator alloc region.
231 void release_mutator_alloc_region();
233 void abandon_gc_alloc_regions();
235 // The to-space memory regions into which objects are being copied during
236 // a GC.
237 HeapRegion* _gc_alloc_regions[GCAllocPurposeCount];
238 size_t _gc_alloc_region_counts[GCAllocPurposeCount];
239 // These are the regions, one per GCAllocPurpose, that are half-full
240 // at the end of a collection and that we want to reuse during the
241 // next collection.
242 HeapRegion* _retained_gc_alloc_regions[GCAllocPurposeCount];
243 // This specifies whether we will keep the last half-full region at
244 // the end of a collection so that it can be reused during the next
245 // collection (this is specified per GCAllocPurpose)
246 bool _retain_gc_alloc_region[GCAllocPurposeCount];
248 // A list of the regions that have been set to be alloc regions in the
249 // current collection.
250 HeapRegion* _gc_alloc_region_list;
252 // Helper for monitoring and management support.
253 G1MonitoringSupport* _g1mm;
255 // Determines PLAB size for a particular allocation purpose.
256 static size_t desired_plab_sz(GCAllocPurpose purpose);
258 // When called by par thread, requires the FreeList_lock to be held.
259 void push_gc_alloc_region(HeapRegion* hr);
261 // This should only be called single-threaded. Undeclares all GC alloc
262 // regions.
263 void forget_alloc_region_list();
265 // Should be used to set an alloc region, because there's other
266 // associated bookkeeping.
267 void set_gc_alloc_region(int purpose, HeapRegion* r);
269 // Check well-formedness of alloc region list.
270 bool check_gc_alloc_regions();
272 // Outside of GC pauses, the number of bytes used in all regions other
273 // than the current allocation region.
274 size_t _summary_bytes_used;
276 // This is used for a quick test on whether a reference points into
277 // the collection set or not. Basically, we have an array, with one
278 // byte per region, and that byte denotes whether the corresponding
279 // region is in the collection set or not. The entry corresponding
280 // the bottom of the heap, i.e., region 0, is pointed to by
281 // _in_cset_fast_test_base. The _in_cset_fast_test field has been
282 // biased so that it actually points to address 0 of the address
283 // space, to make the test as fast as possible (we can simply shift
284 // the address to address into it, instead of having to subtract the
285 // bottom of the heap from the address before shifting it; basically
286 // it works in the same way the card table works).
287 bool* _in_cset_fast_test;
289 // The allocated array used for the fast test on whether a reference
290 // points into the collection set or not. This field is also used to
291 // free the array.
292 bool* _in_cset_fast_test_base;
294 // The length of the _in_cset_fast_test_base array.
295 size_t _in_cset_fast_test_length;
297 volatile unsigned _gc_time_stamp;
299 size_t* _surviving_young_words;
301 void setup_surviving_young_words();
302 void update_surviving_young_words(size_t* surv_young_words);
303 void cleanup_surviving_young_words();
305 // It decides whether an explicit GC should start a concurrent cycle
306 // instead of doing a STW GC. Currently, a concurrent cycle is
307 // explicitly started if:
308 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
309 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
310 bool should_do_concurrent_full_gc(GCCause::Cause cause);
312 // Keeps track of how many "full collections" (i.e., Full GCs or
313 // concurrent cycles) we have completed. The number of them we have
314 // started is maintained in _total_full_collections in CollectedHeap.
315 volatile unsigned int _full_collections_completed;
317 // This is a non-product method that is helpful for testing. It is
318 // called at the end of a GC and artificially expands the heap by
319 // allocating a number of dead regions. This way we can induce very
320 // frequent marking cycles and stress the cleanup / concurrent
321 // cleanup code more (as all the regions that will be allocated by
322 // this method will be found dead by the marking cycle).
323 void allocate_dummy_regions() PRODUCT_RETURN;
325 // These are macros so that, if the assert fires, we get the correct
326 // line number, file, etc.
328 #define heap_locking_asserts_err_msg(_extra_message_) \
329 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
330 (_extra_message_), \
331 BOOL_TO_STR(Heap_lock->owned_by_self()), \
332 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
333 BOOL_TO_STR(Thread::current()->is_VM_thread()))
335 #define assert_heap_locked() \
336 do { \
337 assert(Heap_lock->owned_by_self(), \
338 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
339 } while (0)
341 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
342 do { \
343 assert(Heap_lock->owned_by_self() || \
344 (SafepointSynchronize::is_at_safepoint() && \
345 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
346 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
347 "should be at a safepoint")); \
348 } while (0)
350 #define assert_heap_locked_and_not_at_safepoint() \
351 do { \
352 assert(Heap_lock->owned_by_self() && \
353 !SafepointSynchronize::is_at_safepoint(), \
354 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
355 "should not be at a safepoint")); \
356 } while (0)
358 #define assert_heap_not_locked() \
359 do { \
360 assert(!Heap_lock->owned_by_self(), \
361 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
362 } while (0)
364 #define assert_heap_not_locked_and_not_at_safepoint() \
365 do { \
366 assert(!Heap_lock->owned_by_self() && \
367 !SafepointSynchronize::is_at_safepoint(), \
368 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
369 "should not be at a safepoint")); \
370 } while (0)
372 #define assert_at_safepoint(_should_be_vm_thread_) \
373 do { \
374 assert(SafepointSynchronize::is_at_safepoint() && \
375 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
376 heap_locking_asserts_err_msg("should be at a safepoint")); \
377 } while (0)
379 #define assert_not_at_safepoint() \
380 do { \
381 assert(!SafepointSynchronize::is_at_safepoint(), \
382 heap_locking_asserts_err_msg("should not be at a safepoint")); \
383 } while (0)
385 protected:
387 // Returns "true" iff none of the gc alloc regions have any allocations
388 // since the last call to "save_marks".
389 bool all_alloc_regions_no_allocs_since_save_marks();
390 // Perform finalization stuff on all allocation regions.
391 void retire_all_alloc_regions();
393 // The number of regions allocated to hold humongous objects.
394 int _num_humongous_regions;
395 YoungList* _young_list;
397 // The current policy object for the collector.
398 G1CollectorPolicy* _g1_policy;
400 // This is the second level of trying to allocate a new region. If
401 // new_region() didn't find a region on the free_list, this call will
402 // check whether there's anything available on the
403 // secondary_free_list and/or wait for more regions to appear on
404 // that list, if _free_regions_coming is set.
405 HeapRegion* new_region_try_secondary_free_list();
407 // Try to allocate a single non-humongous HeapRegion sufficient for
408 // an allocation of the given word_size. If do_expand is true,
409 // attempt to expand the heap if necessary to satisfy the allocation
410 // request.
411 HeapRegion* new_region(size_t word_size, bool do_expand);
413 // Try to allocate a new region to be used for allocation by
414 // a GC thread. It will try to expand the heap if no region is
415 // available.
416 HeapRegion* new_gc_alloc_region(int purpose, size_t word_size);
418 // Attempt to satisfy a humongous allocation request of the given
419 // size by finding a contiguous set of free regions of num_regions
420 // length and remove them from the master free list. Return the
421 // index of the first region or G1_NULL_HRS_INDEX if the search
422 // was unsuccessful.
423 size_t humongous_obj_allocate_find_first(size_t num_regions,
424 size_t word_size);
426 // Initialize a contiguous set of free regions of length num_regions
427 // and starting at index first so that they appear as a single
428 // humongous region.
429 HeapWord* humongous_obj_allocate_initialize_regions(size_t first,
430 size_t num_regions,
431 size_t word_size);
433 // Attempt to allocate a humongous object of the given size. Return
434 // NULL if unsuccessful.
435 HeapWord* humongous_obj_allocate(size_t word_size);
437 // The following two methods, allocate_new_tlab() and
438 // mem_allocate(), are the two main entry points from the runtime
439 // into the G1's allocation routines. They have the following
440 // assumptions:
441 //
442 // * They should both be called outside safepoints.
443 //
444 // * They should both be called without holding the Heap_lock.
445 //
446 // * All allocation requests for new TLABs should go to
447 // allocate_new_tlab().
448 //
449 // * All non-TLAB allocation requests should go to mem_allocate()
450 // and mem_allocate() should never be called with is_tlab == true.
451 //
452 // * If either call cannot satisfy the allocation request using the
453 // current allocating region, they will try to get a new one. If
454 // this fails, they will attempt to do an evacuation pause and
455 // retry the allocation.
456 //
457 // * If all allocation attempts fail, even after trying to schedule
458 // an evacuation pause, allocate_new_tlab() will return NULL,
459 // whereas mem_allocate() will attempt a heap expansion and/or
460 // schedule a Full GC.
461 //
462 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
463 // should never be called with word_size being humongous. All
464 // humongous allocation requests should go to mem_allocate() which
465 // will satisfy them with a special path.
467 virtual HeapWord* allocate_new_tlab(size_t word_size);
469 virtual HeapWord* mem_allocate(size_t word_size,
470 bool is_noref,
471 bool is_tlab, /* expected to be false */
472 bool* gc_overhead_limit_was_exceeded);
474 // The following three methods take a gc_count_before_ret
475 // parameter which is used to return the GC count if the method
476 // returns NULL. Given that we are required to read the GC count
477 // while holding the Heap_lock, and these paths will take the
478 // Heap_lock at some point, it's easier to get them to read the GC
479 // count while holding the Heap_lock before they return NULL instead
480 // of the caller (namely: mem_allocate()) having to also take the
481 // Heap_lock just to read the GC count.
483 // First-level mutator allocation attempt: try to allocate out of
484 // the mutator alloc region without taking the Heap_lock. This
485 // should only be used for non-humongous allocations.
486 inline HeapWord* attempt_allocation(size_t word_size,
487 unsigned int* gc_count_before_ret);
489 // Second-level mutator allocation attempt: take the Heap_lock and
490 // retry the allocation attempt, potentially scheduling a GC
491 // pause. This should only be used for non-humongous allocations.
492 HeapWord* attempt_allocation_slow(size_t word_size,
493 unsigned int* gc_count_before_ret);
495 // Takes the Heap_lock and attempts a humongous allocation. It can
496 // potentially schedule a GC pause.
497 HeapWord* attempt_allocation_humongous(size_t word_size,
498 unsigned int* gc_count_before_ret);
500 // Allocation attempt that should be called during safepoints (e.g.,
501 // at the end of a successful GC). expect_null_mutator_alloc_region
502 // specifies whether the mutator alloc region is expected to be NULL
503 // or not.
504 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
505 bool expect_null_mutator_alloc_region);
507 // It dirties the cards that cover the block so that so that the post
508 // write barrier never queues anything when updating objects on this
509 // block. It is assumed (and in fact we assert) that the block
510 // belongs to a young region.
511 inline void dirty_young_block(HeapWord* start, size_t word_size);
513 // Allocate blocks during garbage collection. Will ensure an
514 // allocation region, either by picking one or expanding the
515 // heap, and then allocate a block of the given size. The block
516 // may not be a humongous - it must fit into a single heap region.
517 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size);
519 HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose,
520 HeapRegion* alloc_region,
521 bool par,
522 size_t word_size);
524 // Ensure that no further allocations can happen in "r", bearing in mind
525 // that parallel threads might be attempting allocations.
526 void par_allocate_remaining_space(HeapRegion* r);
528 // Retires an allocation region when it is full or at the end of a
529 // GC pause.
530 void retire_alloc_region(HeapRegion* alloc_region, bool par);
532 // These two methods are the "callbacks" from the G1AllocRegion class.
534 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
535 void retire_mutator_alloc_region(HeapRegion* alloc_region,
536 size_t allocated_bytes);
538 // - if explicit_gc is true, the GC is for a System.gc() or a heap
539 // inspection request and should collect the entire heap
540 // - if clear_all_soft_refs is true, all soft references should be
541 // cleared during the GC
542 // - if explicit_gc is false, word_size describes the allocation that
543 // the GC should attempt (at least) to satisfy
544 // - it returns false if it is unable to do the collection due to the
545 // GC locker being active, true otherwise
546 bool do_collection(bool explicit_gc,
547 bool clear_all_soft_refs,
548 size_t word_size);
550 // Callback from VM_G1CollectFull operation.
551 // Perform a full collection.
552 void do_full_collection(bool clear_all_soft_refs);
554 // Resize the heap if necessary after a full collection. If this is
555 // after a collect-for allocation, "word_size" is the allocation size,
556 // and will be considered part of the used portion of the heap.
557 void resize_if_necessary_after_full_collection(size_t word_size);
559 // Callback from VM_G1CollectForAllocation operation.
560 // This function does everything necessary/possible to satisfy a
561 // failed allocation request (including collection, expansion, etc.)
562 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded);
564 // Attempting to expand the heap sufficiently
565 // to support an allocation of the given "word_size". If
566 // successful, perform the allocation and return the address of the
567 // allocated block, or else "NULL".
568 HeapWord* expand_and_allocate(size_t word_size);
570 public:
572 G1MonitoringSupport* g1mm() { return _g1mm; }
574 // Expand the garbage-first heap by at least the given size (in bytes!).
575 // Returns true if the heap was expanded by the requested amount;
576 // false otherwise.
577 // (Rounds up to a HeapRegion boundary.)
578 bool expand(size_t expand_bytes);
580 // Do anything common to GC's.
581 virtual void gc_prologue(bool full);
582 virtual void gc_epilogue(bool full);
584 // We register a region with the fast "in collection set" test. We
585 // simply set to true the array slot corresponding to this region.
586 void register_region_with_in_cset_fast_test(HeapRegion* r) {
587 assert(_in_cset_fast_test_base != NULL, "sanity");
588 assert(r->in_collection_set(), "invariant");
589 size_t index = r->hrs_index();
590 assert(index < _in_cset_fast_test_length, "invariant");
591 assert(!_in_cset_fast_test_base[index], "invariant");
592 _in_cset_fast_test_base[index] = true;
593 }
595 // This is a fast test on whether a reference points into the
596 // collection set or not. It does not assume that the reference
597 // points into the heap; if it doesn't, it will return false.
598 bool in_cset_fast_test(oop obj) {
599 assert(_in_cset_fast_test != NULL, "sanity");
600 if (_g1_committed.contains((HeapWord*) obj)) {
601 // no need to subtract the bottom of the heap from obj,
602 // _in_cset_fast_test is biased
603 size_t index = ((size_t) obj) >> HeapRegion::LogOfHRGrainBytes;
604 bool ret = _in_cset_fast_test[index];
605 // let's make sure the result is consistent with what the slower
606 // test returns
607 assert( ret || !obj_in_cs(obj), "sanity");
608 assert(!ret || obj_in_cs(obj), "sanity");
609 return ret;
610 } else {
611 return false;
612 }
613 }
615 void clear_cset_fast_test() {
616 assert(_in_cset_fast_test_base != NULL, "sanity");
617 memset(_in_cset_fast_test_base, false,
618 _in_cset_fast_test_length * sizeof(bool));
619 }
621 // This is called at the end of either a concurrent cycle or a Full
622 // GC to update the number of full collections completed. Those two
623 // can happen in a nested fashion, i.e., we start a concurrent
624 // cycle, a Full GC happens half-way through it which ends first,
625 // and then the cycle notices that a Full GC happened and ends
626 // too. The concurrent parameter is a boolean to help us do a bit
627 // tighter consistency checking in the method. If concurrent is
628 // false, the caller is the inner caller in the nesting (i.e., the
629 // Full GC). If concurrent is true, the caller is the outer caller
630 // in this nesting (i.e., the concurrent cycle). Further nesting is
631 // not currently supported. The end of the this call also notifies
632 // the FullGCCount_lock in case a Java thread is waiting for a full
633 // GC to happen (e.g., it called System.gc() with
634 // +ExplicitGCInvokesConcurrent).
635 void increment_full_collections_completed(bool concurrent);
637 unsigned int full_collections_completed() {
638 return _full_collections_completed;
639 }
641 protected:
643 // Shrink the garbage-first heap by at most the given size (in bytes!).
644 // (Rounds down to a HeapRegion boundary.)
645 virtual void shrink(size_t expand_bytes);
646 void shrink_helper(size_t expand_bytes);
648 #if TASKQUEUE_STATS
649 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
650 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
651 void reset_taskqueue_stats();
652 #endif // TASKQUEUE_STATS
654 // Schedule the VM operation that will do an evacuation pause to
655 // satisfy an allocation request of word_size. *succeeded will
656 // return whether the VM operation was successful (it did do an
657 // evacuation pause) or not (another thread beat us to it or the GC
658 // locker was active). Given that we should not be holding the
659 // Heap_lock when we enter this method, we will pass the
660 // gc_count_before (i.e., total_collections()) as a parameter since
661 // it has to be read while holding the Heap_lock. Currently, both
662 // methods that call do_collection_pause() release the Heap_lock
663 // before the call, so it's easy to read gc_count_before just before.
664 HeapWord* do_collection_pause(size_t word_size,
665 unsigned int gc_count_before,
666 bool* succeeded);
668 // The guts of the incremental collection pause, executed by the vm
669 // thread. It returns false if it is unable to do the collection due
670 // to the GC locker being active, true otherwise
671 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
673 // Actually do the work of evacuating the collection set.
674 void evacuate_collection_set();
676 // The g1 remembered set of the heap.
677 G1RemSet* _g1_rem_set;
678 // And it's mod ref barrier set, used to track updates for the above.
679 ModRefBarrierSet* _mr_bs;
681 // A set of cards that cover the objects for which the Rsets should be updated
682 // concurrently after the collection.
683 DirtyCardQueueSet _dirty_card_queue_set;
685 // The Heap Region Rem Set Iterator.
686 HeapRegionRemSetIterator** _rem_set_iterator;
688 // The closure used to refine a single card.
689 RefineCardTableEntryClosure* _refine_cte_cl;
691 // A function to check the consistency of dirty card logs.
692 void check_ct_logs_at_safepoint();
694 // A DirtyCardQueueSet that is used to hold cards that contain
695 // references into the current collection set. This is used to
696 // update the remembered sets of the regions in the collection
697 // set in the event of an evacuation failure.
698 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
700 // After a collection pause, make the regions in the CS into free
701 // regions.
702 void free_collection_set(HeapRegion* cs_head);
704 // Abandon the current collection set without recording policy
705 // statistics or updating free lists.
706 void abandon_collection_set(HeapRegion* cs_head);
708 // Applies "scan_non_heap_roots" to roots outside the heap,
709 // "scan_rs" to roots inside the heap (having done "set_region" to
710 // indicate the region in which the root resides), and does "scan_perm"
711 // (setting the generation to the perm generation.) If "scan_rs" is
712 // NULL, then this step is skipped. The "worker_i"
713 // param is for use with parallel roots processing, and should be
714 // the "i" of the calling parallel worker thread's work(i) function.
715 // In the sequential case this param will be ignored.
716 void g1_process_strong_roots(bool collecting_perm_gen,
717 SharedHeap::ScanningOption so,
718 OopClosure* scan_non_heap_roots,
719 OopsInHeapRegionClosure* scan_rs,
720 OopsInGenClosure* scan_perm,
721 int worker_i);
723 // Apply "blk" to all the weak roots of the system. These include
724 // JNI weak roots, the code cache, system dictionary, symbol table,
725 // string table, and referents of reachable weak refs.
726 void g1_process_weak_roots(OopClosure* root_closure,
727 OopClosure* non_root_closure);
729 // Invoke "save_marks" on all heap regions.
730 void save_marks();
732 // Frees a non-humongous region by initializing its contents and
733 // adding it to the free list that's passed as a parameter (this is
734 // usually a local list which will be appended to the master free
735 // list later). The used bytes of freed regions are accumulated in
736 // pre_used. If par is true, the region's RSet will not be freed
737 // up. The assumption is that this will be done later.
738 void free_region(HeapRegion* hr,
739 size_t* pre_used,
740 FreeRegionList* free_list,
741 bool par);
743 // Frees a humongous region by collapsing it into individual regions
744 // and calling free_region() for each of them. The freed regions
745 // will be added to the free list that's passed as a parameter (this
746 // is usually a local list which will be appended to the master free
747 // list later). The used bytes of freed regions are accumulated in
748 // pre_used. If par is true, the region's RSet will not be freed
749 // up. The assumption is that this will be done later.
750 void free_humongous_region(HeapRegion* hr,
751 size_t* pre_used,
752 FreeRegionList* free_list,
753 HumongousRegionSet* humongous_proxy_set,
754 bool par);
756 // Notifies all the necessary spaces that the committed space has
757 // been updated (either expanded or shrunk). It should be called
758 // after _g1_storage is updated.
759 void update_committed_space(HeapWord* old_end, HeapWord* new_end);
761 // The concurrent marker (and the thread it runs in.)
762 ConcurrentMark* _cm;
763 ConcurrentMarkThread* _cmThread;
764 bool _mark_in_progress;
766 // The concurrent refiner.
767 ConcurrentG1Refine* _cg1r;
769 // The parallel task queues
770 RefToScanQueueSet *_task_queues;
772 // True iff a evacuation has failed in the current collection.
773 bool _evacuation_failed;
775 // Set the attribute indicating whether evacuation has failed in the
776 // current collection.
777 void set_evacuation_failed(bool b) { _evacuation_failed = b; }
779 // Failed evacuations cause some logical from-space objects to have
780 // forwarding pointers to themselves. Reset them.
781 void remove_self_forwarding_pointers();
783 // When one is non-null, so is the other. Together, they each pair is
784 // an object with a preserved mark, and its mark value.
785 GrowableArray<oop>* _objs_with_preserved_marks;
786 GrowableArray<markOop>* _preserved_marks_of_objs;
788 // Preserve the mark of "obj", if necessary, in preparation for its mark
789 // word being overwritten with a self-forwarding-pointer.
790 void preserve_mark_if_necessary(oop obj, markOop m);
792 // The stack of evac-failure objects left to be scanned.
793 GrowableArray<oop>* _evac_failure_scan_stack;
794 // The closure to apply to evac-failure objects.
796 OopsInHeapRegionClosure* _evac_failure_closure;
797 // Set the field above.
798 void
799 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
800 _evac_failure_closure = evac_failure_closure;
801 }
803 // Push "obj" on the scan stack.
804 void push_on_evac_failure_scan_stack(oop obj);
805 // Process scan stack entries until the stack is empty.
806 void drain_evac_failure_scan_stack();
807 // True iff an invocation of "drain_scan_stack" is in progress; to
808 // prevent unnecessary recursion.
809 bool _drain_in_progress;
811 // Do any necessary initialization for evacuation-failure handling.
812 // "cl" is the closure that will be used to process evac-failure
813 // objects.
814 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
815 // Do any necessary cleanup for evacuation-failure handling data
816 // structures.
817 void finalize_for_evac_failure();
819 // An attempt to evacuate "obj" has failed; take necessary steps.
820 oop handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, oop obj);
821 void handle_evacuation_failure_common(oop obj, markOop m);
823 // Ensure that the relevant gc_alloc regions are set.
824 void get_gc_alloc_regions();
825 // We're done with GC alloc regions. We are going to tear down the
826 // gc alloc list and remove the gc alloc tag from all the regions on
827 // that list. However, we will also retain the last (i.e., the one
828 // that is half-full) GC alloc region, per GCAllocPurpose, for
829 // possible reuse during the next collection, provided
830 // _retain_gc_alloc_region[] indicates that it should be the
831 // case. Said regions are kept in the _retained_gc_alloc_regions[]
832 // array. If the parameter totally is set, we will not retain any
833 // regions, irrespective of what _retain_gc_alloc_region[]
834 // indicates.
835 void release_gc_alloc_regions(bool totally);
836 #ifndef PRODUCT
837 // Useful for debugging.
838 void print_gc_alloc_regions();
839 #endif // !PRODUCT
841 // Instance of the concurrent mark is_alive closure for embedding
842 // into the reference processor as the is_alive_non_header. This
843 // prevents unnecessary additions to the discovered lists during
844 // concurrent discovery.
845 G1CMIsAliveClosure _is_alive_closure;
847 // ("Weak") Reference processing support
848 ReferenceProcessor* _ref_processor;
850 enum G1H_process_strong_roots_tasks {
851 G1H_PS_mark_stack_oops_do,
852 G1H_PS_refProcessor_oops_do,
853 // Leave this one last.
854 G1H_PS_NumElements
855 };
857 SubTasksDone* _process_strong_tasks;
859 volatile bool _free_regions_coming;
861 public:
863 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
865 void set_refine_cte_cl_concurrency(bool concurrent);
867 RefToScanQueue *task_queue(int i) const;
869 // A set of cards where updates happened during the GC
870 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
872 // A DirtyCardQueueSet that is used to hold cards that contain
873 // references into the current collection set. This is used to
874 // update the remembered sets of the regions in the collection
875 // set in the event of an evacuation failure.
876 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
877 { return _into_cset_dirty_card_queue_set; }
879 // Create a G1CollectedHeap with the specified policy.
880 // Must call the initialize method afterwards.
881 // May not return if something goes wrong.
882 G1CollectedHeap(G1CollectorPolicy* policy);
884 // Initialize the G1CollectedHeap to have the initial and
885 // maximum sizes, permanent generation, and remembered and barrier sets
886 // specified by the policy object.
887 jint initialize();
889 virtual void ref_processing_init();
891 void set_par_threads(int t) {
892 SharedHeap::set_par_threads(t);
893 _process_strong_tasks->set_n_threads(t);
894 }
896 virtual CollectedHeap::Name kind() const {
897 return CollectedHeap::G1CollectedHeap;
898 }
900 // The current policy object for the collector.
901 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
903 // Adaptive size policy. No such thing for g1.
904 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
906 // The rem set and barrier set.
907 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
908 ModRefBarrierSet* mr_bs() const { return _mr_bs; }
910 // The rem set iterator.
911 HeapRegionRemSetIterator* rem_set_iterator(int i) {
912 return _rem_set_iterator[i];
913 }
915 HeapRegionRemSetIterator* rem_set_iterator() {
916 return _rem_set_iterator[0];
917 }
919 unsigned get_gc_time_stamp() {
920 return _gc_time_stamp;
921 }
923 void reset_gc_time_stamp() {
924 _gc_time_stamp = 0;
925 OrderAccess::fence();
926 }
928 void increment_gc_time_stamp() {
929 ++_gc_time_stamp;
930 OrderAccess::fence();
931 }
933 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
934 DirtyCardQueue* into_cset_dcq,
935 bool concurrent, int worker_i);
937 // The shared block offset table array.
938 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
940 // Reference Processing accessor
941 ReferenceProcessor* ref_processor() { return _ref_processor; }
943 virtual size_t capacity() const;
944 virtual size_t used() const;
945 // This should be called when we're not holding the heap lock. The
946 // result might be a bit inaccurate.
947 size_t used_unlocked() const;
948 size_t recalculate_used() const;
949 #ifndef PRODUCT
950 size_t recalculate_used_regions() const;
951 #endif // PRODUCT
953 // These virtual functions do the actual allocation.
954 // Some heaps may offer a contiguous region for shared non-blocking
955 // allocation, via inlined code (by exporting the address of the top and
956 // end fields defining the extent of the contiguous allocation region.)
957 // But G1CollectedHeap doesn't yet support this.
959 // Return an estimate of the maximum allocation that could be performed
960 // without triggering any collection or expansion activity. In a
961 // generational collector, for example, this is probably the largest
962 // allocation that could be supported (without expansion) in the youngest
963 // generation. It is "unsafe" because no locks are taken; the result
964 // should be treated as an approximation, not a guarantee, for use in
965 // heuristic resizing decisions.
966 virtual size_t unsafe_max_alloc();
968 virtual bool is_maximal_no_gc() const {
969 return _g1_storage.uncommitted_size() == 0;
970 }
972 // The total number of regions in the heap.
973 size_t n_regions() { return _hrs.length(); }
975 // The max number of regions in the heap.
976 size_t max_regions() { return _hrs.max_length(); }
978 // The number of regions that are completely free.
979 size_t free_regions() { return _free_list.length(); }
981 // The number of regions that are not completely free.
982 size_t used_regions() { return n_regions() - free_regions(); }
984 // The number of regions available for "regular" expansion.
985 size_t expansion_regions() { return _expansion_regions; }
987 // Factory method for HeapRegion instances. It will return NULL if
988 // the allocation fails.
989 HeapRegion* new_heap_region(size_t hrs_index, HeapWord* bottom);
991 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
992 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
993 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
994 void verify_dirty_young_regions() PRODUCT_RETURN;
996 // verify_region_sets() performs verification over the region
997 // lists. It will be compiled in the product code to be used when
998 // necessary (i.e., during heap verification).
999 void verify_region_sets();
1001 // verify_region_sets_optional() is planted in the code for
1002 // list verification in non-product builds (and it can be enabled in
1003 // product builds by definning HEAP_REGION_SET_FORCE_VERIFY to be 1).
1004 #if HEAP_REGION_SET_FORCE_VERIFY
1005 void verify_region_sets_optional() {
1006 verify_region_sets();
1007 }
1008 #else // HEAP_REGION_SET_FORCE_VERIFY
1009 void verify_region_sets_optional() { }
1010 #endif // HEAP_REGION_SET_FORCE_VERIFY
1012 #ifdef ASSERT
1013 bool is_on_master_free_list(HeapRegion* hr) {
1014 return hr->containing_set() == &_free_list;
1015 }
1017 bool is_in_humongous_set(HeapRegion* hr) {
1018 return hr->containing_set() == &_humongous_set;
1019 }
1020 #endif // ASSERT
1022 // Wrapper for the region list operations that can be called from
1023 // methods outside this class.
1025 void secondary_free_list_add_as_tail(FreeRegionList* list) {
1026 _secondary_free_list.add_as_tail(list);
1027 }
1029 void append_secondary_free_list() {
1030 _free_list.add_as_head(&_secondary_free_list);
1031 }
1033 void append_secondary_free_list_if_not_empty_with_lock() {
1034 // If the secondary free list looks empty there's no reason to
1035 // take the lock and then try to append it.
1036 if (!_secondary_free_list.is_empty()) {
1037 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1038 append_secondary_free_list();
1039 }
1040 }
1042 void set_free_regions_coming();
1043 void reset_free_regions_coming();
1044 bool free_regions_coming() { return _free_regions_coming; }
1045 void wait_while_free_regions_coming();
1047 // Perform a collection of the heap; intended for use in implementing
1048 // "System.gc". This probably implies as full a collection as the
1049 // "CollectedHeap" supports.
1050 virtual void collect(GCCause::Cause cause);
1052 // The same as above but assume that the caller holds the Heap_lock.
1053 void collect_locked(GCCause::Cause cause);
1055 // This interface assumes that it's being called by the
1056 // vm thread. It collects the heap assuming that the
1057 // heap lock is already held and that we are executing in
1058 // the context of the vm thread.
1059 virtual void collect_as_vm_thread(GCCause::Cause cause);
1061 // True iff a evacuation has failed in the most-recent collection.
1062 bool evacuation_failed() { return _evacuation_failed; }
1064 // It will free a region if it has allocated objects in it that are
1065 // all dead. It calls either free_region() or
1066 // free_humongous_region() depending on the type of the region that
1067 // is passed to it.
1068 void free_region_if_empty(HeapRegion* hr,
1069 size_t* pre_used,
1070 FreeRegionList* free_list,
1071 HumongousRegionSet* humongous_proxy_set,
1072 HRRSCleanupTask* hrrs_cleanup_task,
1073 bool par);
1075 // It appends the free list to the master free list and updates the
1076 // master humongous list according to the contents of the proxy
1077 // list. It also adjusts the total used bytes according to pre_used
1078 // (if par is true, it will do so by taking the ParGCRareEvent_lock).
1079 void update_sets_after_freeing_regions(size_t pre_used,
1080 FreeRegionList* free_list,
1081 HumongousRegionSet* humongous_proxy_set,
1082 bool par);
1084 // Returns "TRUE" iff "p" points into the allocated area of the heap.
1085 virtual bool is_in(const void* p) const;
1087 // Return "TRUE" iff the given object address is within the collection
1088 // set.
1089 inline bool obj_in_cs(oop obj);
1091 // Return "TRUE" iff the given object address is in the reserved
1092 // region of g1 (excluding the permanent generation).
1093 bool is_in_g1_reserved(const void* p) const {
1094 return _g1_reserved.contains(p);
1095 }
1097 // Returns a MemRegion that corresponds to the space that has been
1098 // reserved for the heap
1099 MemRegion g1_reserved() {
1100 return _g1_reserved;
1101 }
1103 // Returns a MemRegion that corresponds to the space that has been
1104 // committed in the heap
1105 MemRegion g1_committed() {
1106 return _g1_committed;
1107 }
1109 virtual bool is_in_closed_subset(const void* p) const;
1111 // Dirty card table entries covering a list of young regions.
1112 void dirtyCardsForYoungRegions(CardTableModRefBS* ct_bs, HeapRegion* list);
1114 // This resets the card table to all zeros. It is used after
1115 // a collection pause which used the card table to claim cards.
1116 void cleanUpCardTable();
1118 // Iteration functions.
1120 // Iterate over all the ref-containing fields of all objects, calling
1121 // "cl.do_oop" on each.
1122 virtual void oop_iterate(OopClosure* cl) {
1123 oop_iterate(cl, true);
1124 }
1125 void oop_iterate(OopClosure* cl, bool do_perm);
1127 // Same as above, restricted to a memory region.
1128 virtual void oop_iterate(MemRegion mr, OopClosure* cl) {
1129 oop_iterate(mr, cl, true);
1130 }
1131 void oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm);
1133 // Iterate over all objects, calling "cl.do_object" on each.
1134 virtual void object_iterate(ObjectClosure* cl) {
1135 object_iterate(cl, true);
1136 }
1137 virtual void safe_object_iterate(ObjectClosure* cl) {
1138 object_iterate(cl, true);
1139 }
1140 void object_iterate(ObjectClosure* cl, bool do_perm);
1142 // Iterate over all objects allocated since the last collection, calling
1143 // "cl.do_object" on each. The heap must have been initialized properly
1144 // to support this function, or else this call will fail.
1145 virtual void object_iterate_since_last_GC(ObjectClosure* cl);
1147 // Iterate over all spaces in use in the heap, in ascending address order.
1148 virtual void space_iterate(SpaceClosure* cl);
1150 // Iterate over heap regions, in address order, terminating the
1151 // iteration early if the "doHeapRegion" method returns "true".
1152 void heap_region_iterate(HeapRegionClosure* blk) const;
1154 // Iterate over heap regions starting with r (or the first region if "r"
1155 // is NULL), in address order, terminating early if the "doHeapRegion"
1156 // method returns "true".
1157 void heap_region_iterate_from(HeapRegion* r, HeapRegionClosure* blk) const;
1159 // Return the region with the given index. It assumes the index is valid.
1160 HeapRegion* region_at(size_t index) const { return _hrs.at(index); }
1162 // Divide the heap region sequence into "chunks" of some size (the number
1163 // of regions divided by the number of parallel threads times some
1164 // overpartition factor, currently 4). Assumes that this will be called
1165 // in parallel by ParallelGCThreads worker threads with discinct worker
1166 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
1167 // calls will use the same "claim_value", and that that claim value is
1168 // different from the claim_value of any heap region before the start of
1169 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by
1170 // attempting to claim the first region in each chunk, and, if
1171 // successful, applying the closure to each region in the chunk (and
1172 // setting the claim value of the second and subsequent regions of the
1173 // chunk.) For now requires that "doHeapRegion" always returns "false",
1174 // i.e., that a closure never attempt to abort a traversal.
1175 void heap_region_par_iterate_chunked(HeapRegionClosure* blk,
1176 int worker,
1177 jint claim_value);
1179 // It resets all the region claim values to the default.
1180 void reset_heap_region_claim_values();
1182 #ifdef ASSERT
1183 bool check_heap_region_claim_values(jint claim_value);
1184 #endif // ASSERT
1186 // Iterate over the regions (if any) in the current collection set.
1187 void collection_set_iterate(HeapRegionClosure* blk);
1189 // As above but starting from region r
1190 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1192 // Returns the first (lowest address) compactible space in the heap.
1193 virtual CompactibleSpace* first_compactible_space();
1195 // A CollectedHeap will contain some number of spaces. This finds the
1196 // space containing a given address, or else returns NULL.
1197 virtual Space* space_containing(const void* addr) const;
1199 // A G1CollectedHeap will contain some number of heap regions. This
1200 // finds the region containing a given address, or else returns NULL.
1201 template <class T>
1202 inline HeapRegion* heap_region_containing(const T addr) const;
1204 // Like the above, but requires "addr" to be in the heap (to avoid a
1205 // null-check), and unlike the above, may return an continuing humongous
1206 // region.
1207 template <class T>
1208 inline HeapRegion* heap_region_containing_raw(const T addr) const;
1210 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1211 // each address in the (reserved) heap is a member of exactly
1212 // one block. The defining characteristic of a block is that it is
1213 // possible to find its size, and thus to progress forward to the next
1214 // block. (Blocks may be of different sizes.) Thus, blocks may
1215 // represent Java objects, or they might be free blocks in a
1216 // free-list-based heap (or subheap), as long as the two kinds are
1217 // distinguishable and the size of each is determinable.
1219 // Returns the address of the start of the "block" that contains the
1220 // address "addr". We say "blocks" instead of "object" since some heaps
1221 // may not pack objects densely; a chunk may either be an object or a
1222 // non-object.
1223 virtual HeapWord* block_start(const void* addr) const;
1225 // Requires "addr" to be the start of a chunk, and returns its size.
1226 // "addr + size" is required to be the start of a new chunk, or the end
1227 // of the active area of the heap.
1228 virtual size_t block_size(const HeapWord* addr) const;
1230 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1231 // the block is an object.
1232 virtual bool block_is_obj(const HeapWord* addr) const;
1234 // Does this heap support heap inspection? (+PrintClassHistogram)
1235 virtual bool supports_heap_inspection() const { return true; }
1237 // Section on thread-local allocation buffers (TLABs)
1238 // See CollectedHeap for semantics.
1240 virtual bool supports_tlab_allocation() const;
1241 virtual size_t tlab_capacity(Thread* thr) const;
1242 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
1244 // Can a compiler initialize a new object without store barriers?
1245 // This permission only extends from the creation of a new object
1246 // via a TLAB up to the first subsequent safepoint. If such permission
1247 // is granted for this heap type, the compiler promises to call
1248 // defer_store_barrier() below on any slow path allocation of
1249 // a new object for which such initializing store barriers will
1250 // have been elided. G1, like CMS, allows this, but should be
1251 // ready to provide a compensating write barrier as necessary
1252 // if that storage came out of a non-young region. The efficiency
1253 // of this implementation depends crucially on being able to
1254 // answer very efficiently in constant time whether a piece of
1255 // storage in the heap comes from a young region or not.
1256 // See ReduceInitialCardMarks.
1257 virtual bool can_elide_tlab_store_barriers() const {
1258 // 6920090: Temporarily disabled, because of lingering
1259 // instabilities related to RICM with G1. In the
1260 // interim, the option ReduceInitialCardMarksForG1
1261 // below is left solely as a debugging device at least
1262 // until 6920109 fixes the instabilities.
1263 return ReduceInitialCardMarksForG1;
1264 }
1266 virtual bool card_mark_must_follow_store() const {
1267 return true;
1268 }
1270 bool is_in_young(const oop obj) {
1271 HeapRegion* hr = heap_region_containing(obj);
1272 return hr != NULL && hr->is_young();
1273 }
1275 #ifdef ASSERT
1276 virtual bool is_in_partial_collection(const void* p);
1277 #endif
1279 virtual bool is_scavengable(const void* addr);
1281 // We don't need barriers for initializing stores to objects
1282 // in the young gen: for the SATB pre-barrier, there is no
1283 // pre-value that needs to be remembered; for the remembered-set
1284 // update logging post-barrier, we don't maintain remembered set
1285 // information for young gen objects. Note that non-generational
1286 // G1 does not have any "young" objects, should not elide
1287 // the rs logging barrier and so should always answer false below.
1288 // However, non-generational G1 (-XX:-G1Gen) appears to have
1289 // bit-rotted so was not tested below.
1290 virtual bool can_elide_initializing_store_barrier(oop new_obj) {
1291 // Re 6920090, 6920109 above.
1292 assert(ReduceInitialCardMarksForG1, "Else cannot be here");
1293 assert(G1Gen || !is_in_young(new_obj),
1294 "Non-generational G1 should never return true below");
1295 return is_in_young(new_obj);
1296 }
1298 // Can a compiler elide a store barrier when it writes
1299 // a permanent oop into the heap? Applies when the compiler
1300 // is storing x to the heap, where x->is_perm() is true.
1301 virtual bool can_elide_permanent_oop_store_barriers() const {
1302 // At least until perm gen collection is also G1-ified, at
1303 // which point this should return false.
1304 return true;
1305 }
1307 // The boundary between a "large" and "small" array of primitives, in
1308 // words.
1309 virtual size_t large_typearray_limit();
1311 // Returns "true" iff the given word_size is "very large".
1312 static bool isHumongous(size_t word_size) {
1313 // Note this has to be strictly greater-than as the TLABs
1314 // are capped at the humongous thresold and we want to
1315 // ensure that we don't try to allocate a TLAB as
1316 // humongous and that we don't allocate a humongous
1317 // object in a TLAB.
1318 return word_size > _humongous_object_threshold_in_words;
1319 }
1321 // Update mod union table with the set of dirty cards.
1322 void updateModUnion();
1324 // Set the mod union bits corresponding to the given memRegion. Note
1325 // that this is always a safe operation, since it doesn't clear any
1326 // bits.
1327 void markModUnionRange(MemRegion mr);
1329 // Records the fact that a marking phase is no longer in progress.
1330 void set_marking_complete() {
1331 _mark_in_progress = false;
1332 }
1333 void set_marking_started() {
1334 _mark_in_progress = true;
1335 }
1336 bool mark_in_progress() {
1337 return _mark_in_progress;
1338 }
1340 // Print the maximum heap capacity.
1341 virtual size_t max_capacity() const;
1343 virtual jlong millis_since_last_gc();
1345 // Perform any cleanup actions necessary before allowing a verification.
1346 virtual void prepare_for_verify();
1348 // Perform verification.
1350 // vo == UsePrevMarking -> use "prev" marking information,
1351 // vo == UseNextMarking -> use "next" marking information
1352 // vo == UseMarkWord -> use the mark word in the object header
1353 //
1354 // NOTE: Only the "prev" marking information is guaranteed to be
1355 // consistent most of the time, so most calls to this should use
1356 // vo == UsePrevMarking.
1357 // Currently, there is only one case where this is called with
1358 // vo == UseNextMarking, which is to verify the "next" marking
1359 // information at the end of remark.
1360 // Currently there is only one place where this is called with
1361 // vo == UseMarkWord, which is to verify the marking during a
1362 // full GC.
1363 void verify(bool allow_dirty, bool silent, VerifyOption vo);
1365 // Override; it uses the "prev" marking information
1366 virtual void verify(bool allow_dirty, bool silent);
1367 // Default behavior by calling print(tty);
1368 virtual void print() const;
1369 // This calls print_on(st, PrintHeapAtGCExtended).
1370 virtual void print_on(outputStream* st) const;
1371 // If extended is true, it will print out information for all
1372 // regions in the heap by calling print_on_extended(st).
1373 virtual void print_on(outputStream* st, bool extended) const;
1374 virtual void print_on_extended(outputStream* st) const;
1376 virtual void print_gc_threads_on(outputStream* st) const;
1377 virtual void gc_threads_do(ThreadClosure* tc) const;
1379 // Override
1380 void print_tracing_info() const;
1382 // Convenience function to be used in situations where the heap type can be
1383 // asserted to be this type.
1384 static G1CollectedHeap* heap();
1386 void empty_young_list();
1388 void set_region_short_lived_locked(HeapRegion* hr);
1389 // add appropriate methods for any other surv rate groups
1391 YoungList* young_list() { return _young_list; }
1393 // debugging
1394 bool check_young_list_well_formed() {
1395 return _young_list->check_list_well_formed();
1396 }
1398 bool check_young_list_empty(bool check_heap,
1399 bool check_sample = true);
1401 // *** Stuff related to concurrent marking. It's not clear to me that so
1402 // many of these need to be public.
1404 // The functions below are helper functions that a subclass of
1405 // "CollectedHeap" can use in the implementation of its virtual
1406 // functions.
1407 // This performs a concurrent marking of the live objects in a
1408 // bitmap off to the side.
1409 void doConcurrentMark();
1411 // Do a full concurrent marking, synchronously.
1412 void do_sync_mark();
1414 bool isMarkedPrev(oop obj) const;
1415 bool isMarkedNext(oop obj) const;
1417 // vo == UsePrevMarking -> use "prev" marking information,
1418 // vo == UseNextMarking -> use "next" marking information,
1419 // vo == UseMarkWord -> use mark word from object header
1420 bool is_obj_dead_cond(const oop obj,
1421 const HeapRegion* hr,
1422 const VerifyOption vo) const {
1424 switch (vo) {
1425 case VerifyOption_G1UsePrevMarking:
1426 return is_obj_dead(obj, hr);
1427 case VerifyOption_G1UseNextMarking:
1428 return is_obj_ill(obj, hr);
1429 default:
1430 assert(vo == VerifyOption_G1UseMarkWord, "must be");
1431 return !obj->is_gc_marked();
1432 }
1433 }
1435 // Determine if an object is dead, given the object and also
1436 // the region to which the object belongs. An object is dead
1437 // iff a) it was not allocated since the last mark and b) it
1438 // is not marked.
1440 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1441 return
1442 !hr->obj_allocated_since_prev_marking(obj) &&
1443 !isMarkedPrev(obj);
1444 }
1446 // This is used when copying an object to survivor space.
1447 // If the object is marked live, then we mark the copy live.
1448 // If the object is allocated since the start of this mark
1449 // cycle, then we mark the copy live.
1450 // If the object has been around since the previous mark
1451 // phase, and hasn't been marked yet during this phase,
1452 // then we don't mark it, we just wait for the
1453 // current marking cycle to get to it.
1455 // This function returns true when an object has been
1456 // around since the previous marking and hasn't yet
1457 // been marked during this marking.
1459 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1460 return
1461 !hr->obj_allocated_since_next_marking(obj) &&
1462 !isMarkedNext(obj);
1463 }
1465 // Determine if an object is dead, given only the object itself.
1466 // This will find the region to which the object belongs and
1467 // then call the region version of the same function.
1469 // Added if it is in permanent gen it isn't dead.
1470 // Added if it is NULL it isn't dead.
1472 // vo == UsePrevMarking -> use "prev" marking information,
1473 // vo == UseNextMarking -> use "next" marking information,
1474 // vo == UseMarkWord -> use mark word from object header
1475 bool is_obj_dead_cond(const oop obj,
1476 const VerifyOption vo) const {
1478 switch (vo) {
1479 case VerifyOption_G1UsePrevMarking:
1480 return is_obj_dead(obj);
1481 case VerifyOption_G1UseNextMarking:
1482 return is_obj_ill(obj);
1483 default:
1484 assert(vo == VerifyOption_G1UseMarkWord, "must be");
1485 return !obj->is_gc_marked();
1486 }
1487 }
1489 bool is_obj_dead(const oop obj) const {
1490 const HeapRegion* hr = heap_region_containing(obj);
1491 if (hr == NULL) {
1492 if (Universe::heap()->is_in_permanent(obj))
1493 return false;
1494 else if (obj == NULL) return false;
1495 else return true;
1496 }
1497 else return is_obj_dead(obj, hr);
1498 }
1500 bool is_obj_ill(const oop obj) const {
1501 const HeapRegion* hr = heap_region_containing(obj);
1502 if (hr == NULL) {
1503 if (Universe::heap()->is_in_permanent(obj))
1504 return false;
1505 else if (obj == NULL) return false;
1506 else return true;
1507 }
1508 else return is_obj_ill(obj, hr);
1509 }
1511 // The following is just to alert the verification code
1512 // that a full collection has occurred and that the
1513 // remembered sets are no longer up to date.
1514 bool _full_collection;
1515 void set_full_collection() { _full_collection = true;}
1516 void clear_full_collection() {_full_collection = false;}
1517 bool full_collection() {return _full_collection;}
1519 ConcurrentMark* concurrent_mark() const { return _cm; }
1520 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1522 // The dirty cards region list is used to record a subset of regions
1523 // whose cards need clearing. The list if populated during the
1524 // remembered set scanning and drained during the card table
1525 // cleanup. Although the methods are reentrant, population/draining
1526 // phases must not overlap. For synchronization purposes the last
1527 // element on the list points to itself.
1528 HeapRegion* _dirty_cards_region_list;
1529 void push_dirty_cards_region(HeapRegion* hr);
1530 HeapRegion* pop_dirty_cards_region();
1532 public:
1533 void stop_conc_gc_threads();
1535 // <NEW PREDICTION>
1537 double predict_region_elapsed_time_ms(HeapRegion* hr, bool young);
1538 void check_if_region_is_too_expensive(double predicted_time_ms);
1539 size_t pending_card_num();
1540 size_t max_pending_card_num();
1541 size_t cards_scanned();
1543 // </NEW PREDICTION>
1545 protected:
1546 size_t _max_heap_capacity;
1547 };
1549 #define use_local_bitmaps 1
1550 #define verify_local_bitmaps 0
1551 #define oop_buffer_length 256
1553 #ifndef PRODUCT
1554 class GCLabBitMap;
1555 class GCLabBitMapClosure: public BitMapClosure {
1556 private:
1557 ConcurrentMark* _cm;
1558 GCLabBitMap* _bitmap;
1560 public:
1561 GCLabBitMapClosure(ConcurrentMark* cm,
1562 GCLabBitMap* bitmap) {
1563 _cm = cm;
1564 _bitmap = bitmap;
1565 }
1567 virtual bool do_bit(size_t offset);
1568 };
1569 #endif // !PRODUCT
1571 class GCLabBitMap: public BitMap {
1572 private:
1573 ConcurrentMark* _cm;
1575 int _shifter;
1576 size_t _bitmap_word_covers_words;
1578 // beginning of the heap
1579 HeapWord* _heap_start;
1581 // this is the actual start of the GCLab
1582 HeapWord* _real_start_word;
1584 // this is the actual end of the GCLab
1585 HeapWord* _real_end_word;
1587 // this is the first word, possibly located before the actual start
1588 // of the GCLab, that corresponds to the first bit of the bitmap
1589 HeapWord* _start_word;
1591 // size of a GCLab in words
1592 size_t _gclab_word_size;
1594 static int shifter() {
1595 return MinObjAlignment - 1;
1596 }
1598 // how many heap words does a single bitmap word corresponds to?
1599 static size_t bitmap_word_covers_words() {
1600 return BitsPerWord << shifter();
1601 }
1603 size_t gclab_word_size() const {
1604 return _gclab_word_size;
1605 }
1607 // Calculates actual GCLab size in words
1608 size_t gclab_real_word_size() const {
1609 return bitmap_size_in_bits(pointer_delta(_real_end_word, _start_word))
1610 / BitsPerWord;
1611 }
1613 static size_t bitmap_size_in_bits(size_t gclab_word_size) {
1614 size_t bits_in_bitmap = gclab_word_size >> shifter();
1615 // We are going to ensure that the beginning of a word in this
1616 // bitmap also corresponds to the beginning of a word in the
1617 // global marking bitmap. To handle the case where a GCLab
1618 // starts from the middle of the bitmap, we need to add enough
1619 // space (i.e. up to a bitmap word) to ensure that we have
1620 // enough bits in the bitmap.
1621 return bits_in_bitmap + BitsPerWord - 1;
1622 }
1623 public:
1624 GCLabBitMap(HeapWord* heap_start, size_t gclab_word_size)
1625 : BitMap(bitmap_size_in_bits(gclab_word_size)),
1626 _cm(G1CollectedHeap::heap()->concurrent_mark()),
1627 _shifter(shifter()),
1628 _bitmap_word_covers_words(bitmap_word_covers_words()),
1629 _heap_start(heap_start),
1630 _gclab_word_size(gclab_word_size),
1631 _real_start_word(NULL),
1632 _real_end_word(NULL),
1633 _start_word(NULL)
1634 {
1635 guarantee( size_in_words() >= bitmap_size_in_words(),
1636 "just making sure");
1637 }
1639 inline unsigned heapWordToOffset(HeapWord* addr) {
1640 unsigned offset = (unsigned) pointer_delta(addr, _start_word) >> _shifter;
1641 assert(offset < size(), "offset should be within bounds");
1642 return offset;
1643 }
1645 inline HeapWord* offsetToHeapWord(size_t offset) {
1646 HeapWord* addr = _start_word + (offset << _shifter);
1647 assert(_real_start_word <= addr && addr < _real_end_word, "invariant");
1648 return addr;
1649 }
1651 bool fields_well_formed() {
1652 bool ret1 = (_real_start_word == NULL) &&
1653 (_real_end_word == NULL) &&
1654 (_start_word == NULL);
1655 if (ret1)
1656 return true;
1658 bool ret2 = _real_start_word >= _start_word &&
1659 _start_word < _real_end_word &&
1660 (_real_start_word + _gclab_word_size) == _real_end_word &&
1661 (_start_word + _gclab_word_size + _bitmap_word_covers_words)
1662 > _real_end_word;
1663 return ret2;
1664 }
1666 inline bool mark(HeapWord* addr) {
1667 guarantee(use_local_bitmaps, "invariant");
1668 assert(fields_well_formed(), "invariant");
1670 if (addr >= _real_start_word && addr < _real_end_word) {
1671 assert(!isMarked(addr), "should not have already been marked");
1673 // first mark it on the bitmap
1674 at_put(heapWordToOffset(addr), true);
1676 return true;
1677 } else {
1678 return false;
1679 }
1680 }
1682 inline bool isMarked(HeapWord* addr) {
1683 guarantee(use_local_bitmaps, "invariant");
1684 assert(fields_well_formed(), "invariant");
1686 return at(heapWordToOffset(addr));
1687 }
1689 void set_buffer(HeapWord* start) {
1690 guarantee(use_local_bitmaps, "invariant");
1691 clear();
1693 assert(start != NULL, "invariant");
1694 _real_start_word = start;
1695 _real_end_word = start + _gclab_word_size;
1697 size_t diff =
1698 pointer_delta(start, _heap_start) % _bitmap_word_covers_words;
1699 _start_word = start - diff;
1701 assert(fields_well_formed(), "invariant");
1702 }
1704 #ifndef PRODUCT
1705 void verify() {
1706 // verify that the marks have been propagated
1707 GCLabBitMapClosure cl(_cm, this);
1708 iterate(&cl);
1709 }
1710 #endif // PRODUCT
1712 void retire() {
1713 guarantee(use_local_bitmaps, "invariant");
1714 assert(fields_well_formed(), "invariant");
1716 if (_start_word != NULL) {
1717 CMBitMap* mark_bitmap = _cm->nextMarkBitMap();
1719 // this means that the bitmap was set up for the GCLab
1720 assert(_real_start_word != NULL && _real_end_word != NULL, "invariant");
1722 mark_bitmap->mostly_disjoint_range_union(this,
1723 0, // always start from the start of the bitmap
1724 _start_word,
1725 gclab_real_word_size());
1726 _cm->grayRegionIfNecessary(MemRegion(_real_start_word, _real_end_word));
1728 #ifndef PRODUCT
1729 if (use_local_bitmaps && verify_local_bitmaps)
1730 verify();
1731 #endif // PRODUCT
1732 } else {
1733 assert(_real_start_word == NULL && _real_end_word == NULL, "invariant");
1734 }
1735 }
1737 size_t bitmap_size_in_words() const {
1738 return (bitmap_size_in_bits(gclab_word_size()) + BitsPerWord - 1) / BitsPerWord;
1739 }
1741 };
1743 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
1744 private:
1745 bool _retired;
1746 bool _during_marking;
1747 GCLabBitMap _bitmap;
1749 public:
1750 G1ParGCAllocBuffer(size_t gclab_word_size) :
1751 ParGCAllocBuffer(gclab_word_size),
1752 _during_marking(G1CollectedHeap::heap()->mark_in_progress()),
1753 _bitmap(G1CollectedHeap::heap()->reserved_region().start(), gclab_word_size),
1754 _retired(false)
1755 { }
1757 inline bool mark(HeapWord* addr) {
1758 guarantee(use_local_bitmaps, "invariant");
1759 assert(_during_marking, "invariant");
1760 return _bitmap.mark(addr);
1761 }
1763 inline void set_buf(HeapWord* buf) {
1764 if (use_local_bitmaps && _during_marking)
1765 _bitmap.set_buffer(buf);
1766 ParGCAllocBuffer::set_buf(buf);
1767 _retired = false;
1768 }
1770 inline void retire(bool end_of_gc, bool retain) {
1771 if (_retired)
1772 return;
1773 if (use_local_bitmaps && _during_marking) {
1774 _bitmap.retire();
1775 }
1776 ParGCAllocBuffer::retire(end_of_gc, retain);
1777 _retired = true;
1778 }
1779 };
1781 class G1ParScanThreadState : public StackObj {
1782 protected:
1783 G1CollectedHeap* _g1h;
1784 RefToScanQueue* _refs;
1785 DirtyCardQueue _dcq;
1786 CardTableModRefBS* _ct_bs;
1787 G1RemSet* _g1_rem;
1789 G1ParGCAllocBuffer _surviving_alloc_buffer;
1790 G1ParGCAllocBuffer _tenured_alloc_buffer;
1791 G1ParGCAllocBuffer* _alloc_buffers[GCAllocPurposeCount];
1792 ageTable _age_table;
1794 size_t _alloc_buffer_waste;
1795 size_t _undo_waste;
1797 OopsInHeapRegionClosure* _evac_failure_cl;
1798 G1ParScanHeapEvacClosure* _evac_cl;
1799 G1ParScanPartialArrayClosure* _partial_scan_cl;
1801 int _hash_seed;
1802 int _queue_num;
1804 size_t _term_attempts;
1806 double _start;
1807 double _start_strong_roots;
1808 double _strong_roots_time;
1809 double _start_term;
1810 double _term_time;
1812 // Map from young-age-index (0 == not young, 1 is youngest) to
1813 // surviving words. base is what we get back from the malloc call
1814 size_t* _surviving_young_words_base;
1815 // this points into the array, as we use the first few entries for padding
1816 size_t* _surviving_young_words;
1818 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t))
1820 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
1822 void add_to_undo_waste(size_t waste) { _undo_waste += waste; }
1824 DirtyCardQueue& dirty_card_queue() { return _dcq; }
1825 CardTableModRefBS* ctbs() { return _ct_bs; }
1827 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) {
1828 if (!from->is_survivor()) {
1829 _g1_rem->par_write_ref(from, p, tid);
1830 }
1831 }
1833 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) {
1834 // If the new value of the field points to the same region or
1835 // is the to-space, we don't need to include it in the Rset updates.
1836 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) {
1837 size_t card_index = ctbs()->index_for(p);
1838 // If the card hasn't been added to the buffer, do it.
1839 if (ctbs()->mark_card_deferred(card_index)) {
1840 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
1841 }
1842 }
1843 }
1845 public:
1846 G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num);
1848 ~G1ParScanThreadState() {
1849 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);
1850 }
1852 RefToScanQueue* refs() { return _refs; }
1853 ageTable* age_table() { return &_age_table; }
1855 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) {
1856 return _alloc_buffers[purpose];
1857 }
1859 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; }
1860 size_t undo_waste() const { return _undo_waste; }
1862 #ifdef ASSERT
1863 bool verify_ref(narrowOop* ref) const;
1864 bool verify_ref(oop* ref) const;
1865 bool verify_task(StarTask ref) const;
1866 #endif // ASSERT
1868 template <class T> void push_on_queue(T* ref) {
1869 assert(verify_ref(ref), "sanity");
1870 refs()->push(ref);
1871 }
1873 template <class T> void update_rs(HeapRegion* from, T* p, int tid) {
1874 if (G1DeferredRSUpdate) {
1875 deferred_rs_update(from, p, tid);
1876 } else {
1877 immediate_rs_update(from, p, tid);
1878 }
1879 }
1881 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
1883 HeapWord* obj = NULL;
1884 size_t gclab_word_size = _g1h->desired_plab_sz(purpose);
1885 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {
1886 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);
1887 assert(gclab_word_size == alloc_buf->word_sz(),
1888 "dynamic resizing is not supported");
1889 add_to_alloc_buffer_waste(alloc_buf->words_remaining());
1890 alloc_buf->retire(false, false);
1892 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size);
1893 if (buf == NULL) return NULL; // Let caller handle allocation failure.
1894 // Otherwise.
1895 alloc_buf->set_buf(buf);
1897 obj = alloc_buf->allocate(word_sz);
1898 assert(obj != NULL, "buffer was definitely big enough...");
1899 } else {
1900 obj = _g1h->par_allocate_during_gc(purpose, word_sz);
1901 }
1902 return obj;
1903 }
1905 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {
1906 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
1907 if (obj != NULL) return obj;
1908 return allocate_slow(purpose, word_sz);
1909 }
1911 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {
1912 if (alloc_buffer(purpose)->contains(obj)) {
1913 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1),
1914 "should contain whole object");
1915 alloc_buffer(purpose)->undo_allocation(obj, word_sz);
1916 } else {
1917 CollectedHeap::fill_with_object(obj, word_sz);
1918 add_to_undo_waste(word_sz);
1919 }
1920 }
1922 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {
1923 _evac_failure_cl = evac_failure_cl;
1924 }
1925 OopsInHeapRegionClosure* evac_failure_closure() {
1926 return _evac_failure_cl;
1927 }
1929 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) {
1930 _evac_cl = evac_cl;
1931 }
1933 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) {
1934 _partial_scan_cl = partial_scan_cl;
1935 }
1937 int* hash_seed() { return &_hash_seed; }
1938 int queue_num() { return _queue_num; }
1940 size_t term_attempts() const { return _term_attempts; }
1941 void note_term_attempt() { _term_attempts++; }
1943 void start_strong_roots() {
1944 _start_strong_roots = os::elapsedTime();
1945 }
1946 void end_strong_roots() {
1947 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
1948 }
1949 double strong_roots_time() const { return _strong_roots_time; }
1951 void start_term_time() {
1952 note_term_attempt();
1953 _start_term = os::elapsedTime();
1954 }
1955 void end_term_time() {
1956 _term_time += (os::elapsedTime() - _start_term);
1957 }
1958 double term_time() const { return _term_time; }
1960 double elapsed_time() const {
1961 return os::elapsedTime() - _start;
1962 }
1964 static void
1965 print_termination_stats_hdr(outputStream* const st = gclog_or_tty);
1966 void
1967 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const;
1969 size_t* surviving_young_words() {
1970 // We add on to hide entry 0 which accumulates surviving words for
1971 // age -1 regions (i.e. non-young ones)
1972 return _surviving_young_words;
1973 }
1975 void retire_alloc_buffers() {
1976 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
1977 size_t waste = _alloc_buffers[ap]->words_remaining();
1978 add_to_alloc_buffer_waste(waste);
1979 _alloc_buffers[ap]->retire(true, false);
1980 }
1981 }
1983 template <class T> void deal_with_reference(T* ref_to_scan) {
1984 if (has_partial_array_mask(ref_to_scan)) {
1985 _partial_scan_cl->do_oop_nv(ref_to_scan);
1986 } else {
1987 // Note: we can use "raw" versions of "region_containing" because
1988 // "obj_to_scan" is definitely in the heap, and is not in a
1989 // humongous region.
1990 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
1991 _evac_cl->set_region(r);
1992 _evac_cl->do_oop_nv(ref_to_scan);
1993 }
1994 }
1996 void deal_with_reference(StarTask ref) {
1997 assert(verify_task(ref), "sanity");
1998 if (ref.is_narrow()) {
1999 deal_with_reference((narrowOop*)ref);
2000 } else {
2001 deal_with_reference((oop*)ref);
2002 }
2003 }
2005 public:
2006 void trim_queue();
2007 };
2009 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP