Fri, 29 Apr 2011 14:59:04 -0400
7035144: G1: nightly failure: Non-dirty cards in region that should be dirty (failures still exist...)
Summary: We should only undirty cards after we decide that they are not on a young region, not before. The fix also includes improvements to the verify_dirty_region() method which print out which cards were not found dirty.
Reviewed-by: johnc, brutisso
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
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
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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/heapRegionSets.hpp"
33 #include "gc_implementation/shared/hSpaceCounters.hpp"
34 #include "gc_implementation/parNew/parGCAllocBuffer.hpp"
35 #include "memory/barrierSet.hpp"
36 #include "memory/memRegion.hpp"
37 #include "memory/sharedHeap.hpp"
39 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
40 // It uses the "Garbage First" heap organization and algorithm, which
41 // may combine concurrent marking with parallel, incremental compaction of
42 // heap subsets that will yield large amounts of garbage.
44 class HeapRegion;
45 class HeapRegionSeq;
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 void rs_length_sampling_init();
107 bool rs_length_sampling_more();
108 void rs_length_sampling_next();
110 void reset_sampled_info() {
111 _last_sampled_rs_lengths = 0;
112 }
113 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }
115 // for development purposes
116 void reset_auxilary_lists();
117 void clear() { _head = NULL; _length = 0; }
119 void clear_survivors() {
120 _survivor_head = NULL;
121 _survivor_tail = NULL;
122 _survivor_length = 0;
123 }
125 HeapRegion* first_region() { return _head; }
126 HeapRegion* first_survivor_region() { return _survivor_head; }
127 HeapRegion* last_survivor_region() { return _survivor_tail; }
129 // debugging
130 bool check_list_well_formed();
131 bool check_list_empty(bool check_sample = true);
132 void print();
133 };
135 class MutatorAllocRegion : public G1AllocRegion {
136 protected:
137 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
138 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
139 public:
140 MutatorAllocRegion()
141 : G1AllocRegion("Mutator Alloc Region", false /* bot_updates */) { }
142 };
144 class RefineCardTableEntryClosure;
145 class G1CollectedHeap : public SharedHeap {
146 friend class VM_G1CollectForAllocation;
147 friend class VM_GenCollectForPermanentAllocation;
148 friend class VM_G1CollectFull;
149 friend class VM_G1IncCollectionPause;
150 friend class VMStructs;
151 friend class MutatorAllocRegion;
153 // Closures used in implementation.
154 friend class G1ParCopyHelper;
155 friend class G1IsAliveClosure;
156 friend class G1EvacuateFollowersClosure;
157 friend class G1ParScanThreadState;
158 friend class G1ParScanClosureSuper;
159 friend class G1ParEvacuateFollowersClosure;
160 friend class G1ParTask;
161 friend class G1FreeGarbageRegionClosure;
162 friend class RefineCardTableEntryClosure;
163 friend class G1PrepareCompactClosure;
164 friend class RegionSorter;
165 friend class RegionResetter;
166 friend class CountRCClosure;
167 friend class EvacPopObjClosure;
168 friend class G1ParCleanupCTTask;
170 // Other related classes.
171 friend class G1MarkSweep;
173 private:
174 // The one and only G1CollectedHeap, so static functions can find it.
175 static G1CollectedHeap* _g1h;
177 static size_t _humongous_object_threshold_in_words;
179 // Storage for the G1 heap (excludes the permanent generation).
180 VirtualSpace _g1_storage;
181 MemRegion _g1_reserved;
183 // The part of _g1_storage that is currently committed.
184 MemRegion _g1_committed;
186 // The maximum part of _g1_storage that has ever been committed.
187 MemRegion _g1_max_committed;
189 // The master free list. It will satisfy all new region allocations.
190 MasterFreeRegionList _free_list;
192 // The secondary free list which contains regions that have been
193 // freed up during the cleanup process. This will be appended to the
194 // master free list when appropriate.
195 SecondaryFreeRegionList _secondary_free_list;
197 // It keeps track of the humongous regions.
198 MasterHumongousRegionSet _humongous_set;
200 // The number of regions we could create by expansion.
201 size_t _expansion_regions;
203 // The block offset table for the G1 heap.
204 G1BlockOffsetSharedArray* _bot_shared;
206 // Move all of the regions off the free lists, then rebuild those free
207 // lists, before and after full GC.
208 void tear_down_region_lists();
209 void rebuild_region_lists();
211 // The sequence of all heap regions in the heap.
212 HeapRegionSeq* _hrs;
214 // Alloc region used to satisfy mutator allocation requests.
215 MutatorAllocRegion _mutator_alloc_region;
217 // It resets the mutator alloc region before new allocations can take place.
218 void init_mutator_alloc_region();
220 // It releases the mutator alloc region.
221 void release_mutator_alloc_region();
223 void abandon_gc_alloc_regions();
225 // The to-space memory regions into which objects are being copied during
226 // a GC.
227 HeapRegion* _gc_alloc_regions[GCAllocPurposeCount];
228 size_t _gc_alloc_region_counts[GCAllocPurposeCount];
229 // These are the regions, one per GCAllocPurpose, that are half-full
230 // at the end of a collection and that we want to reuse during the
231 // next collection.
232 HeapRegion* _retained_gc_alloc_regions[GCAllocPurposeCount];
233 // This specifies whether we will keep the last half-full region at
234 // the end of a collection so that it can be reused during the next
235 // collection (this is specified per GCAllocPurpose)
236 bool _retain_gc_alloc_region[GCAllocPurposeCount];
238 // A list of the regions that have been set to be alloc regions in the
239 // current collection.
240 HeapRegion* _gc_alloc_region_list;
242 // Helper for monitoring and management support.
243 G1MonitoringSupport* _g1mm;
245 // Determines PLAB size for a particular allocation purpose.
246 static size_t desired_plab_sz(GCAllocPurpose purpose);
248 // When called by par thread, requires the FreeList_lock to be held.
249 void push_gc_alloc_region(HeapRegion* hr);
251 // This should only be called single-threaded. Undeclares all GC alloc
252 // regions.
253 void forget_alloc_region_list();
255 // Should be used to set an alloc region, because there's other
256 // associated bookkeeping.
257 void set_gc_alloc_region(int purpose, HeapRegion* r);
259 // Check well-formedness of alloc region list.
260 bool check_gc_alloc_regions();
262 // Outside of GC pauses, the number of bytes used in all regions other
263 // than the current allocation region.
264 size_t _summary_bytes_used;
266 // This is used for a quick test on whether a reference points into
267 // the collection set or not. Basically, we have an array, with one
268 // byte per region, and that byte denotes whether the corresponding
269 // region is in the collection set or not. The entry corresponding
270 // the bottom of the heap, i.e., region 0, is pointed to by
271 // _in_cset_fast_test_base. The _in_cset_fast_test field has been
272 // biased so that it actually points to address 0 of the address
273 // space, to make the test as fast as possible (we can simply shift
274 // the address to address into it, instead of having to subtract the
275 // bottom of the heap from the address before shifting it; basically
276 // it works in the same way the card table works).
277 bool* _in_cset_fast_test;
279 // The allocated array used for the fast test on whether a reference
280 // points into the collection set or not. This field is also used to
281 // free the array.
282 bool* _in_cset_fast_test_base;
284 // The length of the _in_cset_fast_test_base array.
285 size_t _in_cset_fast_test_length;
287 volatile unsigned _gc_time_stamp;
289 size_t* _surviving_young_words;
291 void setup_surviving_young_words();
292 void update_surviving_young_words(size_t* surv_young_words);
293 void cleanup_surviving_young_words();
295 // It decides whether an explicit GC should start a concurrent cycle
296 // instead of doing a STW GC. Currently, a concurrent cycle is
297 // explicitly started if:
298 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
299 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
300 bool should_do_concurrent_full_gc(GCCause::Cause cause);
302 // Keeps track of how many "full collections" (i.e., Full GCs or
303 // concurrent cycles) we have completed. The number of them we have
304 // started is maintained in _total_full_collections in CollectedHeap.
305 volatile unsigned int _full_collections_completed;
307 // This is a non-product method that is helpful for testing. It is
308 // called at the end of a GC and artificially expands the heap by
309 // allocating a number of dead regions. This way we can induce very
310 // frequent marking cycles and stress the cleanup / concurrent
311 // cleanup code more (as all the regions that will be allocated by
312 // this method will be found dead by the marking cycle).
313 void allocate_dummy_regions() PRODUCT_RETURN;
315 // These are macros so that, if the assert fires, we get the correct
316 // line number, file, etc.
318 #define heap_locking_asserts_err_msg(_extra_message_) \
319 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
320 (_extra_message_), \
321 BOOL_TO_STR(Heap_lock->owned_by_self()), \
322 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
323 BOOL_TO_STR(Thread::current()->is_VM_thread()))
325 #define assert_heap_locked() \
326 do { \
327 assert(Heap_lock->owned_by_self(), \
328 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
329 } while (0)
331 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
332 do { \
333 assert(Heap_lock->owned_by_self() || \
334 (SafepointSynchronize::is_at_safepoint() && \
335 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
336 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
337 "should be at a safepoint")); \
338 } while (0)
340 #define assert_heap_locked_and_not_at_safepoint() \
341 do { \
342 assert(Heap_lock->owned_by_self() && \
343 !SafepointSynchronize::is_at_safepoint(), \
344 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
345 "should not be at a safepoint")); \
346 } while (0)
348 #define assert_heap_not_locked() \
349 do { \
350 assert(!Heap_lock->owned_by_self(), \
351 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
352 } while (0)
354 #define assert_heap_not_locked_and_not_at_safepoint() \
355 do { \
356 assert(!Heap_lock->owned_by_self() && \
357 !SafepointSynchronize::is_at_safepoint(), \
358 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
359 "should not be at a safepoint")); \
360 } while (0)
362 #define assert_at_safepoint(_should_be_vm_thread_) \
363 do { \
364 assert(SafepointSynchronize::is_at_safepoint() && \
365 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
366 heap_locking_asserts_err_msg("should be at a safepoint")); \
367 } while (0)
369 #define assert_not_at_safepoint() \
370 do { \
371 assert(!SafepointSynchronize::is_at_safepoint(), \
372 heap_locking_asserts_err_msg("should not be at a safepoint")); \
373 } while (0)
375 protected:
377 // Returns "true" iff none of the gc alloc regions have any allocations
378 // since the last call to "save_marks".
379 bool all_alloc_regions_no_allocs_since_save_marks();
380 // Perform finalization stuff on all allocation regions.
381 void retire_all_alloc_regions();
383 // The number of regions allocated to hold humongous objects.
384 int _num_humongous_regions;
385 YoungList* _young_list;
387 // The current policy object for the collector.
388 G1CollectorPolicy* _g1_policy;
390 // This is the second level of trying to allocate a new region. If
391 // new_region() didn't find a region on the free_list, this call will
392 // check whether there's anything available on the
393 // secondary_free_list and/or wait for more regions to appear on
394 // that list, if _free_regions_coming is set.
395 HeapRegion* new_region_try_secondary_free_list();
397 // Try to allocate a single non-humongous HeapRegion sufficient for
398 // an allocation of the given word_size. If do_expand is true,
399 // attempt to expand the heap if necessary to satisfy the allocation
400 // request.
401 HeapRegion* new_region(size_t word_size, bool do_expand);
403 // Try to allocate a new region to be used for allocation by
404 // a GC thread. It will try to expand the heap if no region is
405 // available.
406 HeapRegion* new_gc_alloc_region(int purpose, size_t word_size);
408 // Attempt to satisfy a humongous allocation request of the given
409 // size by finding a contiguous set of free regions of num_regions
410 // length and remove them from the master free list. Return the
411 // index of the first region or -1 if the search was unsuccessful.
412 int humongous_obj_allocate_find_first(size_t num_regions, size_t word_size);
414 // Initialize a contiguous set of free regions of length num_regions
415 // and starting at index first so that they appear as a single
416 // humongous region.
417 HeapWord* humongous_obj_allocate_initialize_regions(int first,
418 size_t num_regions,
419 size_t word_size);
421 // Attempt to allocate a humongous object of the given size. Return
422 // NULL if unsuccessful.
423 HeapWord* humongous_obj_allocate(size_t word_size);
425 // The following two methods, allocate_new_tlab() and
426 // mem_allocate(), are the two main entry points from the runtime
427 // into the G1's allocation routines. They have the following
428 // assumptions:
429 //
430 // * They should both be called outside safepoints.
431 //
432 // * They should both be called without holding the Heap_lock.
433 //
434 // * All allocation requests for new TLABs should go to
435 // allocate_new_tlab().
436 //
437 // * All non-TLAB allocation requests should go to mem_allocate()
438 // and mem_allocate() should never be called with is_tlab == true.
439 //
440 // * If either call cannot satisfy the allocation request using the
441 // current allocating region, they will try to get a new one. If
442 // this fails, they will attempt to do an evacuation pause and
443 // retry the allocation.
444 //
445 // * If all allocation attempts fail, even after trying to schedule
446 // an evacuation pause, allocate_new_tlab() will return NULL,
447 // whereas mem_allocate() will attempt a heap expansion and/or
448 // schedule a Full GC.
449 //
450 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
451 // should never be called with word_size being humongous. All
452 // humongous allocation requests should go to mem_allocate() which
453 // will satisfy them with a special path.
455 virtual HeapWord* allocate_new_tlab(size_t word_size);
457 virtual HeapWord* mem_allocate(size_t word_size,
458 bool is_noref,
459 bool is_tlab, /* expected to be false */
460 bool* gc_overhead_limit_was_exceeded);
462 // The following three methods take a gc_count_before_ret
463 // parameter which is used to return the GC count if the method
464 // returns NULL. Given that we are required to read the GC count
465 // while holding the Heap_lock, and these paths will take the
466 // Heap_lock at some point, it's easier to get them to read the GC
467 // count while holding the Heap_lock before they return NULL instead
468 // of the caller (namely: mem_allocate()) having to also take the
469 // Heap_lock just to read the GC count.
471 // First-level mutator allocation attempt: try to allocate out of
472 // the mutator alloc region without taking the Heap_lock. This
473 // should only be used for non-humongous allocations.
474 inline HeapWord* attempt_allocation(size_t word_size,
475 unsigned int* gc_count_before_ret);
477 // Second-level mutator allocation attempt: take the Heap_lock and
478 // retry the allocation attempt, potentially scheduling a GC
479 // pause. This should only be used for non-humongous allocations.
480 HeapWord* attempt_allocation_slow(size_t word_size,
481 unsigned int* gc_count_before_ret);
483 // Takes the Heap_lock and attempts a humongous allocation. It can
484 // potentially schedule a GC pause.
485 HeapWord* attempt_allocation_humongous(size_t word_size,
486 unsigned int* gc_count_before_ret);
488 // Allocation attempt that should be called during safepoints (e.g.,
489 // at the end of a successful GC). expect_null_mutator_alloc_region
490 // specifies whether the mutator alloc region is expected to be NULL
491 // or not.
492 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
493 bool expect_null_mutator_alloc_region);
495 // It dirties the cards that cover the block so that so that the post
496 // write barrier never queues anything when updating objects on this
497 // block. It is assumed (and in fact we assert) that the block
498 // belongs to a young region.
499 inline void dirty_young_block(HeapWord* start, size_t word_size);
501 // Allocate blocks during garbage collection. Will ensure an
502 // allocation region, either by picking one or expanding the
503 // heap, and then allocate a block of the given size. The block
504 // may not be a humongous - it must fit into a single heap region.
505 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size);
507 HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose,
508 HeapRegion* alloc_region,
509 bool par,
510 size_t word_size);
512 // Ensure that no further allocations can happen in "r", bearing in mind
513 // that parallel threads might be attempting allocations.
514 void par_allocate_remaining_space(HeapRegion* r);
516 // Retires an allocation region when it is full or at the end of a
517 // GC pause.
518 void retire_alloc_region(HeapRegion* alloc_region, bool par);
520 // These two methods are the "callbacks" from the G1AllocRegion class.
522 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
523 void retire_mutator_alloc_region(HeapRegion* alloc_region,
524 size_t allocated_bytes);
526 // - if explicit_gc is true, the GC is for a System.gc() or a heap
527 // inspection request and should collect the entire heap
528 // - if clear_all_soft_refs is true, all soft references should be
529 // cleared during the GC
530 // - if explicit_gc is false, word_size describes the allocation that
531 // the GC should attempt (at least) to satisfy
532 // - it returns false if it is unable to do the collection due to the
533 // GC locker being active, true otherwise
534 bool do_collection(bool explicit_gc,
535 bool clear_all_soft_refs,
536 size_t word_size);
538 // Callback from VM_G1CollectFull operation.
539 // Perform a full collection.
540 void do_full_collection(bool clear_all_soft_refs);
542 // Resize the heap if necessary after a full collection. If this is
543 // after a collect-for allocation, "word_size" is the allocation size,
544 // and will be considered part of the used portion of the heap.
545 void resize_if_necessary_after_full_collection(size_t word_size);
547 // Callback from VM_G1CollectForAllocation operation.
548 // This function does everything necessary/possible to satisfy a
549 // failed allocation request (including collection, expansion, etc.)
550 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded);
552 // Attempting to expand the heap sufficiently
553 // to support an allocation of the given "word_size". If
554 // successful, perform the allocation and return the address of the
555 // allocated block, or else "NULL".
556 HeapWord* expand_and_allocate(size_t word_size);
558 public:
560 G1MonitoringSupport* g1mm() { return _g1mm; }
562 // Expand the garbage-first heap by at least the given size (in bytes!).
563 // Returns true if the heap was expanded by the requested amount;
564 // false otherwise.
565 // (Rounds up to a HeapRegion boundary.)
566 bool expand(size_t expand_bytes);
568 // Do anything common to GC's.
569 virtual void gc_prologue(bool full);
570 virtual void gc_epilogue(bool full);
572 // We register a region with the fast "in collection set" test. We
573 // simply set to true the array slot corresponding to this region.
574 void register_region_with_in_cset_fast_test(HeapRegion* r) {
575 assert(_in_cset_fast_test_base != NULL, "sanity");
576 assert(r->in_collection_set(), "invariant");
577 int index = r->hrs_index();
578 assert(0 <= index && (size_t) index < _in_cset_fast_test_length, "invariant");
579 assert(!_in_cset_fast_test_base[index], "invariant");
580 _in_cset_fast_test_base[index] = true;
581 }
583 // This is a fast test on whether a reference points into the
584 // collection set or not. It does not assume that the reference
585 // points into the heap; if it doesn't, it will return false.
586 bool in_cset_fast_test(oop obj) {
587 assert(_in_cset_fast_test != NULL, "sanity");
588 if (_g1_committed.contains((HeapWord*) obj)) {
589 // no need to subtract the bottom of the heap from obj,
590 // _in_cset_fast_test is biased
591 size_t index = ((size_t) obj) >> HeapRegion::LogOfHRGrainBytes;
592 bool ret = _in_cset_fast_test[index];
593 // let's make sure the result is consistent with what the slower
594 // test returns
595 assert( ret || !obj_in_cs(obj), "sanity");
596 assert(!ret || obj_in_cs(obj), "sanity");
597 return ret;
598 } else {
599 return false;
600 }
601 }
603 void clear_cset_fast_test() {
604 assert(_in_cset_fast_test_base != NULL, "sanity");
605 memset(_in_cset_fast_test_base, false,
606 _in_cset_fast_test_length * sizeof(bool));
607 }
609 // This is called at the end of either a concurrent cycle or a Full
610 // GC to update the number of full collections completed. Those two
611 // can happen in a nested fashion, i.e., we start a concurrent
612 // cycle, a Full GC happens half-way through it which ends first,
613 // and then the cycle notices that a Full GC happened and ends
614 // too. The concurrent parameter is a boolean to help us do a bit
615 // tighter consistency checking in the method. If concurrent is
616 // false, the caller is the inner caller in the nesting (i.e., the
617 // Full GC). If concurrent is true, the caller is the outer caller
618 // in this nesting (i.e., the concurrent cycle). Further nesting is
619 // not currently supported. The end of the this call also notifies
620 // the FullGCCount_lock in case a Java thread is waiting for a full
621 // GC to happen (e.g., it called System.gc() with
622 // +ExplicitGCInvokesConcurrent).
623 void increment_full_collections_completed(bool concurrent);
625 unsigned int full_collections_completed() {
626 return _full_collections_completed;
627 }
629 protected:
631 // Shrink the garbage-first heap by at most the given size (in bytes!).
632 // (Rounds down to a HeapRegion boundary.)
633 virtual void shrink(size_t expand_bytes);
634 void shrink_helper(size_t expand_bytes);
636 #if TASKQUEUE_STATS
637 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
638 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
639 void reset_taskqueue_stats();
640 #endif // TASKQUEUE_STATS
642 // Schedule the VM operation that will do an evacuation pause to
643 // satisfy an allocation request of word_size. *succeeded will
644 // return whether the VM operation was successful (it did do an
645 // evacuation pause) or not (another thread beat us to it or the GC
646 // locker was active). Given that we should not be holding the
647 // Heap_lock when we enter this method, we will pass the
648 // gc_count_before (i.e., total_collections()) as a parameter since
649 // it has to be read while holding the Heap_lock. Currently, both
650 // methods that call do_collection_pause() release the Heap_lock
651 // before the call, so it's easy to read gc_count_before just before.
652 HeapWord* do_collection_pause(size_t word_size,
653 unsigned int gc_count_before,
654 bool* succeeded);
656 // The guts of the incremental collection pause, executed by the vm
657 // thread. It returns false if it is unable to do the collection due
658 // to the GC locker being active, true otherwise
659 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
661 // Actually do the work of evacuating the collection set.
662 void evacuate_collection_set();
664 // The g1 remembered set of the heap.
665 G1RemSet* _g1_rem_set;
666 // And it's mod ref barrier set, used to track updates for the above.
667 ModRefBarrierSet* _mr_bs;
669 // A set of cards that cover the objects for which the Rsets should be updated
670 // concurrently after the collection.
671 DirtyCardQueueSet _dirty_card_queue_set;
673 // The Heap Region Rem Set Iterator.
674 HeapRegionRemSetIterator** _rem_set_iterator;
676 // The closure used to refine a single card.
677 RefineCardTableEntryClosure* _refine_cte_cl;
679 // A function to check the consistency of dirty card logs.
680 void check_ct_logs_at_safepoint();
682 // A DirtyCardQueueSet that is used to hold cards that contain
683 // references into the current collection set. This is used to
684 // update the remembered sets of the regions in the collection
685 // set in the event of an evacuation failure.
686 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
688 // After a collection pause, make the regions in the CS into free
689 // regions.
690 void free_collection_set(HeapRegion* cs_head);
692 // Abandon the current collection set without recording policy
693 // statistics or updating free lists.
694 void abandon_collection_set(HeapRegion* cs_head);
696 // Applies "scan_non_heap_roots" to roots outside the heap,
697 // "scan_rs" to roots inside the heap (having done "set_region" to
698 // indicate the region in which the root resides), and does "scan_perm"
699 // (setting the generation to the perm generation.) If "scan_rs" is
700 // NULL, then this step is skipped. The "worker_i"
701 // param is for use with parallel roots processing, and should be
702 // the "i" of the calling parallel worker thread's work(i) function.
703 // In the sequential case this param will be ignored.
704 void g1_process_strong_roots(bool collecting_perm_gen,
705 SharedHeap::ScanningOption so,
706 OopClosure* scan_non_heap_roots,
707 OopsInHeapRegionClosure* scan_rs,
708 OopsInGenClosure* scan_perm,
709 int worker_i);
711 // Apply "blk" to all the weak roots of the system. These include
712 // JNI weak roots, the code cache, system dictionary, symbol table,
713 // string table, and referents of reachable weak refs.
714 void g1_process_weak_roots(OopClosure* root_closure,
715 OopClosure* non_root_closure);
717 // Invoke "save_marks" on all heap regions.
718 void save_marks();
720 // Frees a non-humongous region by initializing its contents and
721 // adding it to the free list that's passed as a parameter (this is
722 // usually a local list which will be appended to the master free
723 // list later). The used bytes of freed regions are accumulated in
724 // pre_used. If par is true, the region's RSet will not be freed
725 // up. The assumption is that this will be done later.
726 void free_region(HeapRegion* hr,
727 size_t* pre_used,
728 FreeRegionList* free_list,
729 bool par);
731 // Frees a humongous region by collapsing it into individual regions
732 // and calling free_region() for each of them. The freed regions
733 // will be added to the free list that's passed as a parameter (this
734 // is 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_humongous_region(HeapRegion* hr,
739 size_t* pre_used,
740 FreeRegionList* free_list,
741 HumongousRegionSet* humongous_proxy_set,
742 bool par);
744 // The concurrent marker (and the thread it runs in.)
745 ConcurrentMark* _cm;
746 ConcurrentMarkThread* _cmThread;
747 bool _mark_in_progress;
749 // The concurrent refiner.
750 ConcurrentG1Refine* _cg1r;
752 // The parallel task queues
753 RefToScanQueueSet *_task_queues;
755 // True iff a evacuation has failed in the current collection.
756 bool _evacuation_failed;
758 // Set the attribute indicating whether evacuation has failed in the
759 // current collection.
760 void set_evacuation_failed(bool b) { _evacuation_failed = b; }
762 // Failed evacuations cause some logical from-space objects to have
763 // forwarding pointers to themselves. Reset them.
764 void remove_self_forwarding_pointers();
766 // When one is non-null, so is the other. Together, they each pair is
767 // an object with a preserved mark, and its mark value.
768 GrowableArray<oop>* _objs_with_preserved_marks;
769 GrowableArray<markOop>* _preserved_marks_of_objs;
771 // Preserve the mark of "obj", if necessary, in preparation for its mark
772 // word being overwritten with a self-forwarding-pointer.
773 void preserve_mark_if_necessary(oop obj, markOop m);
775 // The stack of evac-failure objects left to be scanned.
776 GrowableArray<oop>* _evac_failure_scan_stack;
777 // The closure to apply to evac-failure objects.
779 OopsInHeapRegionClosure* _evac_failure_closure;
780 // Set the field above.
781 void
782 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
783 _evac_failure_closure = evac_failure_closure;
784 }
786 // Push "obj" on the scan stack.
787 void push_on_evac_failure_scan_stack(oop obj);
788 // Process scan stack entries until the stack is empty.
789 void drain_evac_failure_scan_stack();
790 // True iff an invocation of "drain_scan_stack" is in progress; to
791 // prevent unnecessary recursion.
792 bool _drain_in_progress;
794 // Do any necessary initialization for evacuation-failure handling.
795 // "cl" is the closure that will be used to process evac-failure
796 // objects.
797 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
798 // Do any necessary cleanup for evacuation-failure handling data
799 // structures.
800 void finalize_for_evac_failure();
802 // An attempt to evacuate "obj" has failed; take necessary steps.
803 oop handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, oop obj);
804 void handle_evacuation_failure_common(oop obj, markOop m);
807 // Ensure that the relevant gc_alloc regions are set.
808 void get_gc_alloc_regions();
809 // We're done with GC alloc regions. We are going to tear down the
810 // gc alloc list and remove the gc alloc tag from all the regions on
811 // that list. However, we will also retain the last (i.e., the one
812 // that is half-full) GC alloc region, per GCAllocPurpose, for
813 // possible reuse during the next collection, provided
814 // _retain_gc_alloc_region[] indicates that it should be the
815 // case. Said regions are kept in the _retained_gc_alloc_regions[]
816 // array. If the parameter totally is set, we will not retain any
817 // regions, irrespective of what _retain_gc_alloc_region[]
818 // indicates.
819 void release_gc_alloc_regions(bool totally);
820 #ifndef PRODUCT
821 // Useful for debugging.
822 void print_gc_alloc_regions();
823 #endif // !PRODUCT
825 // Instance of the concurrent mark is_alive closure for embedding
826 // into the reference processor as the is_alive_non_header. This
827 // prevents unnecessary additions to the discovered lists during
828 // concurrent discovery.
829 G1CMIsAliveClosure _is_alive_closure;
831 // ("Weak") Reference processing support
832 ReferenceProcessor* _ref_processor;
834 enum G1H_process_strong_roots_tasks {
835 G1H_PS_mark_stack_oops_do,
836 G1H_PS_refProcessor_oops_do,
837 // Leave this one last.
838 G1H_PS_NumElements
839 };
841 SubTasksDone* _process_strong_tasks;
843 volatile bool _free_regions_coming;
845 public:
847 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
849 void set_refine_cte_cl_concurrency(bool concurrent);
851 RefToScanQueue *task_queue(int i) const;
853 // A set of cards where updates happened during the GC
854 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
856 // A DirtyCardQueueSet that is used to hold cards that contain
857 // references into the current collection set. This is used to
858 // update the remembered sets of the regions in the collection
859 // set in the event of an evacuation failure.
860 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
861 { return _into_cset_dirty_card_queue_set; }
863 // Create a G1CollectedHeap with the specified policy.
864 // Must call the initialize method afterwards.
865 // May not return if something goes wrong.
866 G1CollectedHeap(G1CollectorPolicy* policy);
868 // Initialize the G1CollectedHeap to have the initial and
869 // maximum sizes, permanent generation, and remembered and barrier sets
870 // specified by the policy object.
871 jint initialize();
873 virtual void ref_processing_init();
875 void set_par_threads(int t) {
876 SharedHeap::set_par_threads(t);
877 _process_strong_tasks->set_n_threads(t);
878 }
880 virtual CollectedHeap::Name kind() const {
881 return CollectedHeap::G1CollectedHeap;
882 }
884 // The current policy object for the collector.
885 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
887 // Adaptive size policy. No such thing for g1.
888 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
890 // The rem set and barrier set.
891 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
892 ModRefBarrierSet* mr_bs() const { return _mr_bs; }
894 // The rem set iterator.
895 HeapRegionRemSetIterator* rem_set_iterator(int i) {
896 return _rem_set_iterator[i];
897 }
899 HeapRegionRemSetIterator* rem_set_iterator() {
900 return _rem_set_iterator[0];
901 }
903 unsigned get_gc_time_stamp() {
904 return _gc_time_stamp;
905 }
907 void reset_gc_time_stamp() {
908 _gc_time_stamp = 0;
909 OrderAccess::fence();
910 }
912 void increment_gc_time_stamp() {
913 ++_gc_time_stamp;
914 OrderAccess::fence();
915 }
917 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
918 DirtyCardQueue* into_cset_dcq,
919 bool concurrent, int worker_i);
921 // The shared block offset table array.
922 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
924 // Reference Processing accessor
925 ReferenceProcessor* ref_processor() { return _ref_processor; }
927 virtual size_t capacity() const;
928 virtual size_t used() const;
929 // This should be called when we're not holding the heap lock. The
930 // result might be a bit inaccurate.
931 size_t used_unlocked() const;
932 size_t recalculate_used() const;
933 #ifndef PRODUCT
934 size_t recalculate_used_regions() const;
935 #endif // PRODUCT
937 // These virtual functions do the actual allocation.
938 // Some heaps may offer a contiguous region for shared non-blocking
939 // allocation, via inlined code (by exporting the address of the top and
940 // end fields defining the extent of the contiguous allocation region.)
941 // But G1CollectedHeap doesn't yet support this.
943 // Return an estimate of the maximum allocation that could be performed
944 // without triggering any collection or expansion activity. In a
945 // generational collector, for example, this is probably the largest
946 // allocation that could be supported (without expansion) in the youngest
947 // generation. It is "unsafe" because no locks are taken; the result
948 // should be treated as an approximation, not a guarantee, for use in
949 // heuristic resizing decisions.
950 virtual size_t unsafe_max_alloc();
952 virtual bool is_maximal_no_gc() const {
953 return _g1_storage.uncommitted_size() == 0;
954 }
956 // The total number of regions in the heap.
957 size_t n_regions();
959 // The number of regions that are completely free.
960 size_t max_regions();
962 // The number of regions that are completely free.
963 size_t free_regions() {
964 return _free_list.length();
965 }
967 // The number of regions that are not completely free.
968 size_t used_regions() { return n_regions() - free_regions(); }
970 // The number of regions available for "regular" expansion.
971 size_t expansion_regions() { return _expansion_regions; }
973 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
974 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
975 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
976 void verify_dirty_young_regions() PRODUCT_RETURN;
978 // verify_region_sets() performs verification over the region
979 // lists. It will be compiled in the product code to be used when
980 // necessary (i.e., during heap verification).
981 void verify_region_sets();
983 // verify_region_sets_optional() is planted in the code for
984 // list verification in non-product builds (and it can be enabled in
985 // product builds by definning HEAP_REGION_SET_FORCE_VERIFY to be 1).
986 #if HEAP_REGION_SET_FORCE_VERIFY
987 void verify_region_sets_optional() {
988 verify_region_sets();
989 }
990 #else // HEAP_REGION_SET_FORCE_VERIFY
991 void verify_region_sets_optional() { }
992 #endif // HEAP_REGION_SET_FORCE_VERIFY
994 #ifdef ASSERT
995 bool is_on_master_free_list(HeapRegion* hr) {
996 return hr->containing_set() == &_free_list;
997 }
999 bool is_in_humongous_set(HeapRegion* hr) {
1000 return hr->containing_set() == &_humongous_set;
1001 }
1002 #endif // ASSERT
1004 // Wrapper for the region list operations that can be called from
1005 // methods outside this class.
1007 void secondary_free_list_add_as_tail(FreeRegionList* list) {
1008 _secondary_free_list.add_as_tail(list);
1009 }
1011 void append_secondary_free_list() {
1012 _free_list.add_as_head(&_secondary_free_list);
1013 }
1015 void append_secondary_free_list_if_not_empty_with_lock() {
1016 // If the secondary free list looks empty there's no reason to
1017 // take the lock and then try to append it.
1018 if (!_secondary_free_list.is_empty()) {
1019 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1020 append_secondary_free_list();
1021 }
1022 }
1024 void set_free_regions_coming();
1025 void reset_free_regions_coming();
1026 bool free_regions_coming() { return _free_regions_coming; }
1027 void wait_while_free_regions_coming();
1029 // Perform a collection of the heap; intended for use in implementing
1030 // "System.gc". This probably implies as full a collection as the
1031 // "CollectedHeap" supports.
1032 virtual void collect(GCCause::Cause cause);
1034 // The same as above but assume that the caller holds the Heap_lock.
1035 void collect_locked(GCCause::Cause cause);
1037 // This interface assumes that it's being called by the
1038 // vm thread. It collects the heap assuming that the
1039 // heap lock is already held and that we are executing in
1040 // the context of the vm thread.
1041 virtual void collect_as_vm_thread(GCCause::Cause cause);
1043 // True iff a evacuation has failed in the most-recent collection.
1044 bool evacuation_failed() { return _evacuation_failed; }
1046 // It will free a region if it has allocated objects in it that are
1047 // all dead. It calls either free_region() or
1048 // free_humongous_region() depending on the type of the region that
1049 // is passed to it.
1050 void free_region_if_empty(HeapRegion* hr,
1051 size_t* pre_used,
1052 FreeRegionList* free_list,
1053 HumongousRegionSet* humongous_proxy_set,
1054 HRRSCleanupTask* hrrs_cleanup_task,
1055 bool par);
1057 // It appends the free list to the master free list and updates the
1058 // master humongous list according to the contents of the proxy
1059 // list. It also adjusts the total used bytes according to pre_used
1060 // (if par is true, it will do so by taking the ParGCRareEvent_lock).
1061 void update_sets_after_freeing_regions(size_t pre_used,
1062 FreeRegionList* free_list,
1063 HumongousRegionSet* humongous_proxy_set,
1064 bool par);
1066 // Returns "TRUE" iff "p" points into the allocated area of the heap.
1067 virtual bool is_in(const void* p) const;
1069 // Return "TRUE" iff the given object address is within the collection
1070 // set.
1071 inline bool obj_in_cs(oop obj);
1073 // Return "TRUE" iff the given object address is in the reserved
1074 // region of g1 (excluding the permanent generation).
1075 bool is_in_g1_reserved(const void* p) const {
1076 return _g1_reserved.contains(p);
1077 }
1079 // Returns a MemRegion that corresponds to the space that has been
1080 // reserved for the heap
1081 MemRegion g1_reserved() {
1082 return _g1_reserved;
1083 }
1085 // Returns a MemRegion that corresponds to the space that has been
1086 // committed in the heap
1087 MemRegion g1_committed() {
1088 return _g1_committed;
1089 }
1091 virtual bool is_in_closed_subset(const void* p) const;
1093 // Dirty card table entries covering a list of young regions.
1094 void dirtyCardsForYoungRegions(CardTableModRefBS* ct_bs, HeapRegion* list);
1096 // This resets the card table to all zeros. It is used after
1097 // a collection pause which used the card table to claim cards.
1098 void cleanUpCardTable();
1100 // Iteration functions.
1102 // Iterate over all the ref-containing fields of all objects, calling
1103 // "cl.do_oop" on each.
1104 virtual void oop_iterate(OopClosure* cl) {
1105 oop_iterate(cl, true);
1106 }
1107 void oop_iterate(OopClosure* cl, bool do_perm);
1109 // Same as above, restricted to a memory region.
1110 virtual void oop_iterate(MemRegion mr, OopClosure* cl) {
1111 oop_iterate(mr, cl, true);
1112 }
1113 void oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm);
1115 // Iterate over all objects, calling "cl.do_object" on each.
1116 virtual void object_iterate(ObjectClosure* cl) {
1117 object_iterate(cl, true);
1118 }
1119 virtual void safe_object_iterate(ObjectClosure* cl) {
1120 object_iterate(cl, true);
1121 }
1122 void object_iterate(ObjectClosure* cl, bool do_perm);
1124 // Iterate over all objects allocated since the last collection, calling
1125 // "cl.do_object" on each. The heap must have been initialized properly
1126 // to support this function, or else this call will fail.
1127 virtual void object_iterate_since_last_GC(ObjectClosure* cl);
1129 // Iterate over all spaces in use in the heap, in ascending address order.
1130 virtual void space_iterate(SpaceClosure* cl);
1132 // Iterate over heap regions, in address order, terminating the
1133 // iteration early if the "doHeapRegion" method returns "true".
1134 void heap_region_iterate(HeapRegionClosure* blk);
1136 // Iterate over heap regions starting with r (or the first region if "r"
1137 // is NULL), in address order, terminating early if the "doHeapRegion"
1138 // method returns "true".
1139 void heap_region_iterate_from(HeapRegion* r, HeapRegionClosure* blk);
1141 // As above but starting from the region at index idx.
1142 void heap_region_iterate_from(int idx, HeapRegionClosure* blk);
1144 HeapRegion* region_at(size_t idx);
1146 // Divide the heap region sequence into "chunks" of some size (the number
1147 // of regions divided by the number of parallel threads times some
1148 // overpartition factor, currently 4). Assumes that this will be called
1149 // in parallel by ParallelGCThreads worker threads with discinct worker
1150 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
1151 // calls will use the same "claim_value", and that that claim value is
1152 // different from the claim_value of any heap region before the start of
1153 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by
1154 // attempting to claim the first region in each chunk, and, if
1155 // successful, applying the closure to each region in the chunk (and
1156 // setting the claim value of the second and subsequent regions of the
1157 // chunk.) For now requires that "doHeapRegion" always returns "false",
1158 // i.e., that a closure never attempt to abort a traversal.
1159 void heap_region_par_iterate_chunked(HeapRegionClosure* blk,
1160 int worker,
1161 jint claim_value);
1163 // It resets all the region claim values to the default.
1164 void reset_heap_region_claim_values();
1166 #ifdef ASSERT
1167 bool check_heap_region_claim_values(jint claim_value);
1168 #endif // ASSERT
1170 // Iterate over the regions (if any) in the current collection set.
1171 void collection_set_iterate(HeapRegionClosure* blk);
1173 // As above but starting from region r
1174 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1176 // Returns the first (lowest address) compactible space in the heap.
1177 virtual CompactibleSpace* first_compactible_space();
1179 // A CollectedHeap will contain some number of spaces. This finds the
1180 // space containing a given address, or else returns NULL.
1181 virtual Space* space_containing(const void* addr) const;
1183 // A G1CollectedHeap will contain some number of heap regions. This
1184 // finds the region containing a given address, or else returns NULL.
1185 HeapRegion* heap_region_containing(const void* addr) const;
1187 // Like the above, but requires "addr" to be in the heap (to avoid a
1188 // null-check), and unlike the above, may return an continuing humongous
1189 // region.
1190 HeapRegion* heap_region_containing_raw(const void* addr) const;
1192 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1193 // each address in the (reserved) heap is a member of exactly
1194 // one block. The defining characteristic of a block is that it is
1195 // possible to find its size, and thus to progress forward to the next
1196 // block. (Blocks may be of different sizes.) Thus, blocks may
1197 // represent Java objects, or they might be free blocks in a
1198 // free-list-based heap (or subheap), as long as the two kinds are
1199 // distinguishable and the size of each is determinable.
1201 // Returns the address of the start of the "block" that contains the
1202 // address "addr". We say "blocks" instead of "object" since some heaps
1203 // may not pack objects densely; a chunk may either be an object or a
1204 // non-object.
1205 virtual HeapWord* block_start(const void* addr) const;
1207 // Requires "addr" to be the start of a chunk, and returns its size.
1208 // "addr + size" is required to be the start of a new chunk, or the end
1209 // of the active area of the heap.
1210 virtual size_t block_size(const HeapWord* addr) const;
1212 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1213 // the block is an object.
1214 virtual bool block_is_obj(const HeapWord* addr) const;
1216 // Does this heap support heap inspection? (+PrintClassHistogram)
1217 virtual bool supports_heap_inspection() const { return true; }
1219 // Section on thread-local allocation buffers (TLABs)
1220 // See CollectedHeap for semantics.
1222 virtual bool supports_tlab_allocation() const;
1223 virtual size_t tlab_capacity(Thread* thr) const;
1224 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
1226 // Can a compiler initialize a new object without store barriers?
1227 // This permission only extends from the creation of a new object
1228 // via a TLAB up to the first subsequent safepoint. If such permission
1229 // is granted for this heap type, the compiler promises to call
1230 // defer_store_barrier() below on any slow path allocation of
1231 // a new object for which such initializing store barriers will
1232 // have been elided. G1, like CMS, allows this, but should be
1233 // ready to provide a compensating write barrier as necessary
1234 // if that storage came out of a non-young region. The efficiency
1235 // of this implementation depends crucially on being able to
1236 // answer very efficiently in constant time whether a piece of
1237 // storage in the heap comes from a young region or not.
1238 // See ReduceInitialCardMarks.
1239 virtual bool can_elide_tlab_store_barriers() const {
1240 // 6920090: Temporarily disabled, because of lingering
1241 // instabilities related to RICM with G1. In the
1242 // interim, the option ReduceInitialCardMarksForG1
1243 // below is left solely as a debugging device at least
1244 // until 6920109 fixes the instabilities.
1245 return ReduceInitialCardMarksForG1;
1246 }
1248 virtual bool card_mark_must_follow_store() const {
1249 return true;
1250 }
1252 bool is_in_young(oop obj) {
1253 HeapRegion* hr = heap_region_containing(obj);
1254 return hr != NULL && hr->is_young();
1255 }
1257 // We don't need barriers for initializing stores to objects
1258 // in the young gen: for the SATB pre-barrier, there is no
1259 // pre-value that needs to be remembered; for the remembered-set
1260 // update logging post-barrier, we don't maintain remembered set
1261 // information for young gen objects. Note that non-generational
1262 // G1 does not have any "young" objects, should not elide
1263 // the rs logging barrier and so should always answer false below.
1264 // However, non-generational G1 (-XX:-G1Gen) appears to have
1265 // bit-rotted so was not tested below.
1266 virtual bool can_elide_initializing_store_barrier(oop new_obj) {
1267 // Re 6920090, 6920109 above.
1268 assert(ReduceInitialCardMarksForG1, "Else cannot be here");
1269 assert(G1Gen || !is_in_young(new_obj),
1270 "Non-generational G1 should never return true below");
1271 return is_in_young(new_obj);
1272 }
1274 // Can a compiler elide a store barrier when it writes
1275 // a permanent oop into the heap? Applies when the compiler
1276 // is storing x to the heap, where x->is_perm() is true.
1277 virtual bool can_elide_permanent_oop_store_barriers() const {
1278 // At least until perm gen collection is also G1-ified, at
1279 // which point this should return false.
1280 return true;
1281 }
1283 // The boundary between a "large" and "small" array of primitives, in
1284 // words.
1285 virtual size_t large_typearray_limit();
1287 // Returns "true" iff the given word_size is "very large".
1288 static bool isHumongous(size_t word_size) {
1289 // Note this has to be strictly greater-than as the TLABs
1290 // are capped at the humongous thresold and we want to
1291 // ensure that we don't try to allocate a TLAB as
1292 // humongous and that we don't allocate a humongous
1293 // object in a TLAB.
1294 return word_size > _humongous_object_threshold_in_words;
1295 }
1297 // Update mod union table with the set of dirty cards.
1298 void updateModUnion();
1300 // Set the mod union bits corresponding to the given memRegion. Note
1301 // that this is always a safe operation, since it doesn't clear any
1302 // bits.
1303 void markModUnionRange(MemRegion mr);
1305 // Records the fact that a marking phase is no longer in progress.
1306 void set_marking_complete() {
1307 _mark_in_progress = false;
1308 }
1309 void set_marking_started() {
1310 _mark_in_progress = true;
1311 }
1312 bool mark_in_progress() {
1313 return _mark_in_progress;
1314 }
1316 // Print the maximum heap capacity.
1317 virtual size_t max_capacity() const;
1319 virtual jlong millis_since_last_gc();
1321 // Perform any cleanup actions necessary before allowing a verification.
1322 virtual void prepare_for_verify();
1324 // Perform verification.
1326 // use_prev_marking == true -> use "prev" marking information,
1327 // use_prev_marking == false -> use "next" marking information
1328 // NOTE: Only the "prev" marking information is guaranteed to be
1329 // consistent most of the time, so most calls to this should use
1330 // use_prev_marking == true. Currently, there is only one case where
1331 // this is called with use_prev_marking == false, which is to verify
1332 // the "next" marking information at the end of remark.
1333 void verify(bool allow_dirty, bool silent, bool use_prev_marking);
1335 // Override; it uses the "prev" marking information
1336 virtual void verify(bool allow_dirty, bool silent);
1337 // Default behavior by calling print(tty);
1338 virtual void print() const;
1339 // This calls print_on(st, PrintHeapAtGCExtended).
1340 virtual void print_on(outputStream* st) const;
1341 // If extended is true, it will print out information for all
1342 // regions in the heap by calling print_on_extended(st).
1343 virtual void print_on(outputStream* st, bool extended) const;
1344 virtual void print_on_extended(outputStream* st) const;
1346 virtual void print_gc_threads_on(outputStream* st) const;
1347 virtual void gc_threads_do(ThreadClosure* tc) const;
1349 // Override
1350 void print_tracing_info() const;
1352 // If "addr" is a pointer into the (reserved?) heap, returns a positive
1353 // number indicating the "arena" within the heap in which "addr" falls.
1354 // Or else returns 0.
1355 virtual int addr_to_arena_id(void* addr) const;
1357 // Convenience function to be used in situations where the heap type can be
1358 // asserted to be this type.
1359 static G1CollectedHeap* heap();
1361 void empty_young_list();
1363 void set_region_short_lived_locked(HeapRegion* hr);
1364 // add appropriate methods for any other surv rate groups
1366 YoungList* young_list() { return _young_list; }
1368 // debugging
1369 bool check_young_list_well_formed() {
1370 return _young_list->check_list_well_formed();
1371 }
1373 bool check_young_list_empty(bool check_heap,
1374 bool check_sample = true);
1376 // *** Stuff related to concurrent marking. It's not clear to me that so
1377 // many of these need to be public.
1379 // The functions below are helper functions that a subclass of
1380 // "CollectedHeap" can use in the implementation of its virtual
1381 // functions.
1382 // This performs a concurrent marking of the live objects in a
1383 // bitmap off to the side.
1384 void doConcurrentMark();
1386 // This is called from the marksweep collector which then does
1387 // a concurrent mark and verifies that the results agree with
1388 // the stop the world marking.
1389 void checkConcurrentMark();
1390 void do_sync_mark();
1392 bool isMarkedPrev(oop obj) const;
1393 bool isMarkedNext(oop obj) const;
1395 // use_prev_marking == true -> use "prev" marking information,
1396 // use_prev_marking == false -> use "next" marking information
1397 bool is_obj_dead_cond(const oop obj,
1398 const HeapRegion* hr,
1399 const bool use_prev_marking) const {
1400 if (use_prev_marking) {
1401 return is_obj_dead(obj, hr);
1402 } else {
1403 return is_obj_ill(obj, hr);
1404 }
1405 }
1407 // Determine if an object is dead, given the object and also
1408 // the region to which the object belongs. An object is dead
1409 // iff a) it was not allocated since the last mark and b) it
1410 // is not marked.
1412 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1413 return
1414 !hr->obj_allocated_since_prev_marking(obj) &&
1415 !isMarkedPrev(obj);
1416 }
1418 // This is used when copying an object to survivor space.
1419 // If the object is marked live, then we mark the copy live.
1420 // If the object is allocated since the start of this mark
1421 // cycle, then we mark the copy live.
1422 // If the object has been around since the previous mark
1423 // phase, and hasn't been marked yet during this phase,
1424 // then we don't mark it, we just wait for the
1425 // current marking cycle to get to it.
1427 // This function returns true when an object has been
1428 // around since the previous marking and hasn't yet
1429 // been marked during this marking.
1431 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1432 return
1433 !hr->obj_allocated_since_next_marking(obj) &&
1434 !isMarkedNext(obj);
1435 }
1437 // Determine if an object is dead, given only the object itself.
1438 // This will find the region to which the object belongs and
1439 // then call the region version of the same function.
1441 // Added if it is in permanent gen it isn't dead.
1442 // Added if it is NULL it isn't dead.
1444 // use_prev_marking == true -> use "prev" marking information,
1445 // use_prev_marking == false -> use "next" marking information
1446 bool is_obj_dead_cond(const oop obj,
1447 const bool use_prev_marking) {
1448 if (use_prev_marking) {
1449 return is_obj_dead(obj);
1450 } else {
1451 return is_obj_ill(obj);
1452 }
1453 }
1455 bool is_obj_dead(const oop obj) {
1456 const HeapRegion* hr = heap_region_containing(obj);
1457 if (hr == NULL) {
1458 if (Universe::heap()->is_in_permanent(obj))
1459 return false;
1460 else if (obj == NULL) return false;
1461 else return true;
1462 }
1463 else return is_obj_dead(obj, hr);
1464 }
1466 bool is_obj_ill(const oop obj) {
1467 const HeapRegion* hr = heap_region_containing(obj);
1468 if (hr == NULL) {
1469 if (Universe::heap()->is_in_permanent(obj))
1470 return false;
1471 else if (obj == NULL) return false;
1472 else return true;
1473 }
1474 else return is_obj_ill(obj, hr);
1475 }
1477 // The following is just to alert the verification code
1478 // that a full collection has occurred and that the
1479 // remembered sets are no longer up to date.
1480 bool _full_collection;
1481 void set_full_collection() { _full_collection = true;}
1482 void clear_full_collection() {_full_collection = false;}
1483 bool full_collection() {return _full_collection;}
1485 ConcurrentMark* concurrent_mark() const { return _cm; }
1486 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1488 // The dirty cards region list is used to record a subset of regions
1489 // whose cards need clearing. The list if populated during the
1490 // remembered set scanning and drained during the card table
1491 // cleanup. Although the methods are reentrant, population/draining
1492 // phases must not overlap. For synchronization purposes the last
1493 // element on the list points to itself.
1494 HeapRegion* _dirty_cards_region_list;
1495 void push_dirty_cards_region(HeapRegion* hr);
1496 HeapRegion* pop_dirty_cards_region();
1498 public:
1499 void stop_conc_gc_threads();
1501 // <NEW PREDICTION>
1503 double predict_region_elapsed_time_ms(HeapRegion* hr, bool young);
1504 void check_if_region_is_too_expensive(double predicted_time_ms);
1505 size_t pending_card_num();
1506 size_t max_pending_card_num();
1507 size_t cards_scanned();
1509 // </NEW PREDICTION>
1511 protected:
1512 size_t _max_heap_capacity;
1513 };
1515 #define use_local_bitmaps 1
1516 #define verify_local_bitmaps 0
1517 #define oop_buffer_length 256
1519 #ifndef PRODUCT
1520 class GCLabBitMap;
1521 class GCLabBitMapClosure: public BitMapClosure {
1522 private:
1523 ConcurrentMark* _cm;
1524 GCLabBitMap* _bitmap;
1526 public:
1527 GCLabBitMapClosure(ConcurrentMark* cm,
1528 GCLabBitMap* bitmap) {
1529 _cm = cm;
1530 _bitmap = bitmap;
1531 }
1533 virtual bool do_bit(size_t offset);
1534 };
1535 #endif // !PRODUCT
1537 class GCLabBitMap: public BitMap {
1538 private:
1539 ConcurrentMark* _cm;
1541 int _shifter;
1542 size_t _bitmap_word_covers_words;
1544 // beginning of the heap
1545 HeapWord* _heap_start;
1547 // this is the actual start of the GCLab
1548 HeapWord* _real_start_word;
1550 // this is the actual end of the GCLab
1551 HeapWord* _real_end_word;
1553 // this is the first word, possibly located before the actual start
1554 // of the GCLab, that corresponds to the first bit of the bitmap
1555 HeapWord* _start_word;
1557 // size of a GCLab in words
1558 size_t _gclab_word_size;
1560 static int shifter() {
1561 return MinObjAlignment - 1;
1562 }
1564 // how many heap words does a single bitmap word corresponds to?
1565 static size_t bitmap_word_covers_words() {
1566 return BitsPerWord << shifter();
1567 }
1569 size_t gclab_word_size() const {
1570 return _gclab_word_size;
1571 }
1573 // Calculates actual GCLab size in words
1574 size_t gclab_real_word_size() const {
1575 return bitmap_size_in_bits(pointer_delta(_real_end_word, _start_word))
1576 / BitsPerWord;
1577 }
1579 static size_t bitmap_size_in_bits(size_t gclab_word_size) {
1580 size_t bits_in_bitmap = gclab_word_size >> shifter();
1581 // We are going to ensure that the beginning of a word in this
1582 // bitmap also corresponds to the beginning of a word in the
1583 // global marking bitmap. To handle the case where a GCLab
1584 // starts from the middle of the bitmap, we need to add enough
1585 // space (i.e. up to a bitmap word) to ensure that we have
1586 // enough bits in the bitmap.
1587 return bits_in_bitmap + BitsPerWord - 1;
1588 }
1589 public:
1590 GCLabBitMap(HeapWord* heap_start, size_t gclab_word_size)
1591 : BitMap(bitmap_size_in_bits(gclab_word_size)),
1592 _cm(G1CollectedHeap::heap()->concurrent_mark()),
1593 _shifter(shifter()),
1594 _bitmap_word_covers_words(bitmap_word_covers_words()),
1595 _heap_start(heap_start),
1596 _gclab_word_size(gclab_word_size),
1597 _real_start_word(NULL),
1598 _real_end_word(NULL),
1599 _start_word(NULL)
1600 {
1601 guarantee( size_in_words() >= bitmap_size_in_words(),
1602 "just making sure");
1603 }
1605 inline unsigned heapWordToOffset(HeapWord* addr) {
1606 unsigned offset = (unsigned) pointer_delta(addr, _start_word) >> _shifter;
1607 assert(offset < size(), "offset should be within bounds");
1608 return offset;
1609 }
1611 inline HeapWord* offsetToHeapWord(size_t offset) {
1612 HeapWord* addr = _start_word + (offset << _shifter);
1613 assert(_real_start_word <= addr && addr < _real_end_word, "invariant");
1614 return addr;
1615 }
1617 bool fields_well_formed() {
1618 bool ret1 = (_real_start_word == NULL) &&
1619 (_real_end_word == NULL) &&
1620 (_start_word == NULL);
1621 if (ret1)
1622 return true;
1624 bool ret2 = _real_start_word >= _start_word &&
1625 _start_word < _real_end_word &&
1626 (_real_start_word + _gclab_word_size) == _real_end_word &&
1627 (_start_word + _gclab_word_size + _bitmap_word_covers_words)
1628 > _real_end_word;
1629 return ret2;
1630 }
1632 inline bool mark(HeapWord* addr) {
1633 guarantee(use_local_bitmaps, "invariant");
1634 assert(fields_well_formed(), "invariant");
1636 if (addr >= _real_start_word && addr < _real_end_word) {
1637 assert(!isMarked(addr), "should not have already been marked");
1639 // first mark it on the bitmap
1640 at_put(heapWordToOffset(addr), true);
1642 return true;
1643 } else {
1644 return false;
1645 }
1646 }
1648 inline bool isMarked(HeapWord* addr) {
1649 guarantee(use_local_bitmaps, "invariant");
1650 assert(fields_well_formed(), "invariant");
1652 return at(heapWordToOffset(addr));
1653 }
1655 void set_buffer(HeapWord* start) {
1656 guarantee(use_local_bitmaps, "invariant");
1657 clear();
1659 assert(start != NULL, "invariant");
1660 _real_start_word = start;
1661 _real_end_word = start + _gclab_word_size;
1663 size_t diff =
1664 pointer_delta(start, _heap_start) % _bitmap_word_covers_words;
1665 _start_word = start - diff;
1667 assert(fields_well_formed(), "invariant");
1668 }
1670 #ifndef PRODUCT
1671 void verify() {
1672 // verify that the marks have been propagated
1673 GCLabBitMapClosure cl(_cm, this);
1674 iterate(&cl);
1675 }
1676 #endif // PRODUCT
1678 void retire() {
1679 guarantee(use_local_bitmaps, "invariant");
1680 assert(fields_well_formed(), "invariant");
1682 if (_start_word != NULL) {
1683 CMBitMap* mark_bitmap = _cm->nextMarkBitMap();
1685 // this means that the bitmap was set up for the GCLab
1686 assert(_real_start_word != NULL && _real_end_word != NULL, "invariant");
1688 mark_bitmap->mostly_disjoint_range_union(this,
1689 0, // always start from the start of the bitmap
1690 _start_word,
1691 gclab_real_word_size());
1692 _cm->grayRegionIfNecessary(MemRegion(_real_start_word, _real_end_word));
1694 #ifndef PRODUCT
1695 if (use_local_bitmaps && verify_local_bitmaps)
1696 verify();
1697 #endif // PRODUCT
1698 } else {
1699 assert(_real_start_word == NULL && _real_end_word == NULL, "invariant");
1700 }
1701 }
1703 size_t bitmap_size_in_words() const {
1704 return (bitmap_size_in_bits(gclab_word_size()) + BitsPerWord - 1) / BitsPerWord;
1705 }
1707 };
1709 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
1710 private:
1711 bool _retired;
1712 bool _during_marking;
1713 GCLabBitMap _bitmap;
1715 public:
1716 G1ParGCAllocBuffer(size_t gclab_word_size) :
1717 ParGCAllocBuffer(gclab_word_size),
1718 _during_marking(G1CollectedHeap::heap()->mark_in_progress()),
1719 _bitmap(G1CollectedHeap::heap()->reserved_region().start(), gclab_word_size),
1720 _retired(false)
1721 { }
1723 inline bool mark(HeapWord* addr) {
1724 guarantee(use_local_bitmaps, "invariant");
1725 assert(_during_marking, "invariant");
1726 return _bitmap.mark(addr);
1727 }
1729 inline void set_buf(HeapWord* buf) {
1730 if (use_local_bitmaps && _during_marking)
1731 _bitmap.set_buffer(buf);
1732 ParGCAllocBuffer::set_buf(buf);
1733 _retired = false;
1734 }
1736 inline void retire(bool end_of_gc, bool retain) {
1737 if (_retired)
1738 return;
1739 if (use_local_bitmaps && _during_marking) {
1740 _bitmap.retire();
1741 }
1742 ParGCAllocBuffer::retire(end_of_gc, retain);
1743 _retired = true;
1744 }
1745 };
1747 class G1ParScanThreadState : public StackObj {
1748 protected:
1749 G1CollectedHeap* _g1h;
1750 RefToScanQueue* _refs;
1751 DirtyCardQueue _dcq;
1752 CardTableModRefBS* _ct_bs;
1753 G1RemSet* _g1_rem;
1755 G1ParGCAllocBuffer _surviving_alloc_buffer;
1756 G1ParGCAllocBuffer _tenured_alloc_buffer;
1757 G1ParGCAllocBuffer* _alloc_buffers[GCAllocPurposeCount];
1758 ageTable _age_table;
1760 size_t _alloc_buffer_waste;
1761 size_t _undo_waste;
1763 OopsInHeapRegionClosure* _evac_failure_cl;
1764 G1ParScanHeapEvacClosure* _evac_cl;
1765 G1ParScanPartialArrayClosure* _partial_scan_cl;
1767 int _hash_seed;
1768 int _queue_num;
1770 size_t _term_attempts;
1772 double _start;
1773 double _start_strong_roots;
1774 double _strong_roots_time;
1775 double _start_term;
1776 double _term_time;
1778 // Map from young-age-index (0 == not young, 1 is youngest) to
1779 // surviving words. base is what we get back from the malloc call
1780 size_t* _surviving_young_words_base;
1781 // this points into the array, as we use the first few entries for padding
1782 size_t* _surviving_young_words;
1784 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t))
1786 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
1788 void add_to_undo_waste(size_t waste) { _undo_waste += waste; }
1790 DirtyCardQueue& dirty_card_queue() { return _dcq; }
1791 CardTableModRefBS* ctbs() { return _ct_bs; }
1793 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) {
1794 if (!from->is_survivor()) {
1795 _g1_rem->par_write_ref(from, p, tid);
1796 }
1797 }
1799 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) {
1800 // If the new value of the field points to the same region or
1801 // is the to-space, we don't need to include it in the Rset updates.
1802 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) {
1803 size_t card_index = ctbs()->index_for(p);
1804 // If the card hasn't been added to the buffer, do it.
1805 if (ctbs()->mark_card_deferred(card_index)) {
1806 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
1807 }
1808 }
1809 }
1811 public:
1812 G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num);
1814 ~G1ParScanThreadState() {
1815 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);
1816 }
1818 RefToScanQueue* refs() { return _refs; }
1819 ageTable* age_table() { return &_age_table; }
1821 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) {
1822 return _alloc_buffers[purpose];
1823 }
1825 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; }
1826 size_t undo_waste() const { return _undo_waste; }
1828 #ifdef ASSERT
1829 bool verify_ref(narrowOop* ref) const;
1830 bool verify_ref(oop* ref) const;
1831 bool verify_task(StarTask ref) const;
1832 #endif // ASSERT
1834 template <class T> void push_on_queue(T* ref) {
1835 assert(verify_ref(ref), "sanity");
1836 refs()->push(ref);
1837 }
1839 template <class T> void update_rs(HeapRegion* from, T* p, int tid) {
1840 if (G1DeferredRSUpdate) {
1841 deferred_rs_update(from, p, tid);
1842 } else {
1843 immediate_rs_update(from, p, tid);
1844 }
1845 }
1847 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
1849 HeapWord* obj = NULL;
1850 size_t gclab_word_size = _g1h->desired_plab_sz(purpose);
1851 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {
1852 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);
1853 assert(gclab_word_size == alloc_buf->word_sz(),
1854 "dynamic resizing is not supported");
1855 add_to_alloc_buffer_waste(alloc_buf->words_remaining());
1856 alloc_buf->retire(false, false);
1858 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size);
1859 if (buf == NULL) return NULL; // Let caller handle allocation failure.
1860 // Otherwise.
1861 alloc_buf->set_buf(buf);
1863 obj = alloc_buf->allocate(word_sz);
1864 assert(obj != NULL, "buffer was definitely big enough...");
1865 } else {
1866 obj = _g1h->par_allocate_during_gc(purpose, word_sz);
1867 }
1868 return obj;
1869 }
1871 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {
1872 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
1873 if (obj != NULL) return obj;
1874 return allocate_slow(purpose, word_sz);
1875 }
1877 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {
1878 if (alloc_buffer(purpose)->contains(obj)) {
1879 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1),
1880 "should contain whole object");
1881 alloc_buffer(purpose)->undo_allocation(obj, word_sz);
1882 } else {
1883 CollectedHeap::fill_with_object(obj, word_sz);
1884 add_to_undo_waste(word_sz);
1885 }
1886 }
1888 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {
1889 _evac_failure_cl = evac_failure_cl;
1890 }
1891 OopsInHeapRegionClosure* evac_failure_closure() {
1892 return _evac_failure_cl;
1893 }
1895 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) {
1896 _evac_cl = evac_cl;
1897 }
1899 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) {
1900 _partial_scan_cl = partial_scan_cl;
1901 }
1903 int* hash_seed() { return &_hash_seed; }
1904 int queue_num() { return _queue_num; }
1906 size_t term_attempts() const { return _term_attempts; }
1907 void note_term_attempt() { _term_attempts++; }
1909 void start_strong_roots() {
1910 _start_strong_roots = os::elapsedTime();
1911 }
1912 void end_strong_roots() {
1913 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
1914 }
1915 double strong_roots_time() const { return _strong_roots_time; }
1917 void start_term_time() {
1918 note_term_attempt();
1919 _start_term = os::elapsedTime();
1920 }
1921 void end_term_time() {
1922 _term_time += (os::elapsedTime() - _start_term);
1923 }
1924 double term_time() const { return _term_time; }
1926 double elapsed_time() const {
1927 return os::elapsedTime() - _start;
1928 }
1930 static void
1931 print_termination_stats_hdr(outputStream* const st = gclog_or_tty);
1932 void
1933 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const;
1935 size_t* surviving_young_words() {
1936 // We add on to hide entry 0 which accumulates surviving words for
1937 // age -1 regions (i.e. non-young ones)
1938 return _surviving_young_words;
1939 }
1941 void retire_alloc_buffers() {
1942 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
1943 size_t waste = _alloc_buffers[ap]->words_remaining();
1944 add_to_alloc_buffer_waste(waste);
1945 _alloc_buffers[ap]->retire(true, false);
1946 }
1947 }
1949 template <class T> void deal_with_reference(T* ref_to_scan) {
1950 if (has_partial_array_mask(ref_to_scan)) {
1951 _partial_scan_cl->do_oop_nv(ref_to_scan);
1952 } else {
1953 // Note: we can use "raw" versions of "region_containing" because
1954 // "obj_to_scan" is definitely in the heap, and is not in a
1955 // humongous region.
1956 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
1957 _evac_cl->set_region(r);
1958 _evac_cl->do_oop_nv(ref_to_scan);
1959 }
1960 }
1962 void deal_with_reference(StarTask ref) {
1963 assert(verify_task(ref), "sanity");
1964 if (ref.is_narrow()) {
1965 deal_with_reference((narrowOop*)ref);
1966 } else {
1967 deal_with_reference((oop*)ref);
1968 }
1969 }
1971 public:
1972 void trim_queue();
1973 };
1975 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP