Thu, 28 Jun 2012 17:03:16 -0400
6995781: Native Memory Tracking (Phase 1)
7151532: DCmd for hotspot native memory tracking
Summary: Implementation of native memory tracking phase 1, which tracks VM native memory usage, and related DCmd
Reviewed-by: acorn, coleenp, fparain
1 /*
2 * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
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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/g1HRPrinter.hpp"
31 #include "gc_implementation/g1/g1RemSet.hpp"
32 #include "gc_implementation/g1/g1MonitoringSupport.hpp"
33 #include "gc_implementation/g1/heapRegionSeq.hpp"
34 #include "gc_implementation/g1/heapRegionSets.hpp"
35 #include "gc_implementation/shared/hSpaceCounters.hpp"
36 #include "gc_implementation/parNew/parGCAllocBuffer.hpp"
37 #include "memory/barrierSet.hpp"
38 #include "memory/memRegion.hpp"
39 #include "memory/sharedHeap.hpp"
41 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
42 // It uses the "Garbage First" heap organization and algorithm, which
43 // may combine concurrent marking with parallel, incremental compaction of
44 // heap subsets that will yield large amounts of garbage.
46 class HeapRegion;
47 class HRRSCleanupTask;
48 class PermanentGenerationSpec;
49 class GenerationSpec;
50 class OopsInHeapRegionClosure;
51 class G1ScanHeapEvacClosure;
52 class ObjectClosure;
53 class SpaceClosure;
54 class CompactibleSpaceClosure;
55 class Space;
56 class G1CollectorPolicy;
57 class GenRemSet;
58 class G1RemSet;
59 class HeapRegionRemSetIterator;
60 class ConcurrentMark;
61 class ConcurrentMarkThread;
62 class ConcurrentG1Refine;
63 class GenerationCounters;
65 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue;
66 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
68 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
69 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
71 enum GCAllocPurpose {
72 GCAllocForTenured,
73 GCAllocForSurvived,
74 GCAllocPurposeCount
75 };
77 class YoungList : public CHeapObj<mtGC> {
78 private:
79 G1CollectedHeap* _g1h;
81 HeapRegion* _head;
83 HeapRegion* _survivor_head;
84 HeapRegion* _survivor_tail;
86 HeapRegion* _curr;
88 uint _length;
89 uint _survivor_length;
91 size_t _last_sampled_rs_lengths;
92 size_t _sampled_rs_lengths;
94 void empty_list(HeapRegion* list);
96 public:
97 YoungList(G1CollectedHeap* g1h);
99 void push_region(HeapRegion* hr);
100 void add_survivor_region(HeapRegion* hr);
102 void empty_list();
103 bool is_empty() { return _length == 0; }
104 uint length() { return _length; }
105 uint survivor_length() { return _survivor_length; }
107 // Currently we do not keep track of the used byte sum for the
108 // young list and the survivors and it'd be quite a lot of work to
109 // do so. When we'll eventually replace the young list with
110 // instances of HeapRegionLinkedList we'll get that for free. So,
111 // we'll report the more accurate information then.
112 size_t eden_used_bytes() {
113 assert(length() >= survivor_length(), "invariant");
114 return (size_t) (length() - survivor_length()) * HeapRegion::GrainBytes;
115 }
116 size_t survivor_used_bytes() {
117 return (size_t) survivor_length() * HeapRegion::GrainBytes;
118 }
120 void rs_length_sampling_init();
121 bool rs_length_sampling_more();
122 void rs_length_sampling_next();
124 void reset_sampled_info() {
125 _last_sampled_rs_lengths = 0;
126 }
127 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }
129 // for development purposes
130 void reset_auxilary_lists();
131 void clear() { _head = NULL; _length = 0; }
133 void clear_survivors() {
134 _survivor_head = NULL;
135 _survivor_tail = NULL;
136 _survivor_length = 0;
137 }
139 HeapRegion* first_region() { return _head; }
140 HeapRegion* first_survivor_region() { return _survivor_head; }
141 HeapRegion* last_survivor_region() { return _survivor_tail; }
143 // debugging
144 bool check_list_well_formed();
145 bool check_list_empty(bool check_sample = true);
146 void print();
147 };
149 class MutatorAllocRegion : public G1AllocRegion {
150 protected:
151 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
152 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
153 public:
154 MutatorAllocRegion()
155 : G1AllocRegion("Mutator Alloc Region", false /* bot_updates */) { }
156 };
158 // The G1 STW is alive closure.
159 // An instance is embedded into the G1CH and used as the
160 // (optional) _is_alive_non_header closure in the STW
161 // reference processor. It is also extensively used during
162 // refence processing during STW evacuation pauses.
163 class G1STWIsAliveClosure: public BoolObjectClosure {
164 G1CollectedHeap* _g1;
165 public:
166 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
167 void do_object(oop p) { assert(false, "Do not call."); }
168 bool do_object_b(oop p);
169 };
171 class SurvivorGCAllocRegion : public G1AllocRegion {
172 protected:
173 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
174 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
175 public:
176 SurvivorGCAllocRegion()
177 : G1AllocRegion("Survivor GC Alloc Region", false /* bot_updates */) { }
178 };
180 class OldGCAllocRegion : public G1AllocRegion {
181 protected:
182 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
183 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
184 public:
185 OldGCAllocRegion()
186 : G1AllocRegion("Old GC Alloc Region", true /* bot_updates */) { }
187 };
189 class RefineCardTableEntryClosure;
191 class G1CollectedHeap : public SharedHeap {
192 friend class VM_G1CollectForAllocation;
193 friend class VM_GenCollectForPermanentAllocation;
194 friend class VM_G1CollectFull;
195 friend class VM_G1IncCollectionPause;
196 friend class VMStructs;
197 friend class MutatorAllocRegion;
198 friend class SurvivorGCAllocRegion;
199 friend class OldGCAllocRegion;
201 // Closures used in implementation.
202 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
203 friend class G1ParCopyClosure;
204 friend class G1IsAliveClosure;
205 friend class G1EvacuateFollowersClosure;
206 friend class G1ParScanThreadState;
207 friend class G1ParScanClosureSuper;
208 friend class G1ParEvacuateFollowersClosure;
209 friend class G1ParTask;
210 friend class G1FreeGarbageRegionClosure;
211 friend class RefineCardTableEntryClosure;
212 friend class G1PrepareCompactClosure;
213 friend class RegionSorter;
214 friend class RegionResetter;
215 friend class CountRCClosure;
216 friend class EvacPopObjClosure;
217 friend class G1ParCleanupCTTask;
219 // Other related classes.
220 friend class G1MarkSweep;
222 private:
223 // The one and only G1CollectedHeap, so static functions can find it.
224 static G1CollectedHeap* _g1h;
226 static size_t _humongous_object_threshold_in_words;
228 // Storage for the G1 heap (excludes the permanent generation).
229 VirtualSpace _g1_storage;
230 MemRegion _g1_reserved;
232 // The part of _g1_storage that is currently committed.
233 MemRegion _g1_committed;
235 // The master free list. It will satisfy all new region allocations.
236 MasterFreeRegionList _free_list;
238 // The secondary free list which contains regions that have been
239 // freed up during the cleanup process. This will be appended to the
240 // master free list when appropriate.
241 SecondaryFreeRegionList _secondary_free_list;
243 // It keeps track of the old regions.
244 MasterOldRegionSet _old_set;
246 // It keeps track of the humongous regions.
247 MasterHumongousRegionSet _humongous_set;
249 // The number of regions we could create by expansion.
250 uint _expansion_regions;
252 // The block offset table for the G1 heap.
253 G1BlockOffsetSharedArray* _bot_shared;
255 // Tears down the region sets / lists so that they are empty and the
256 // regions on the heap do not belong to a region set / list. The
257 // only exception is the humongous set which we leave unaltered. If
258 // free_list_only is true, it will only tear down the master free
259 // list. It is called before a Full GC (free_list_only == false) or
260 // before heap shrinking (free_list_only == true).
261 void tear_down_region_sets(bool free_list_only);
263 // Rebuilds the region sets / lists so that they are repopulated to
264 // reflect the contents of the heap. The only exception is the
265 // humongous set which was not torn down in the first place. If
266 // free_list_only is true, it will only rebuild the master free
267 // list. It is called after a Full GC (free_list_only == false) or
268 // after heap shrinking (free_list_only == true).
269 void rebuild_region_sets(bool free_list_only);
271 // The sequence of all heap regions in the heap.
272 HeapRegionSeq _hrs;
274 // Alloc region used to satisfy mutator allocation requests.
275 MutatorAllocRegion _mutator_alloc_region;
277 // Alloc region used to satisfy allocation requests by the GC for
278 // survivor objects.
279 SurvivorGCAllocRegion _survivor_gc_alloc_region;
281 // Alloc region used to satisfy allocation requests by the GC for
282 // old objects.
283 OldGCAllocRegion _old_gc_alloc_region;
285 // The last old region we allocated to during the last GC.
286 // Typically, it is not full so we should re-use it during the next GC.
287 HeapRegion* _retained_old_gc_alloc_region;
289 // It specifies whether we should attempt to expand the heap after a
290 // region allocation failure. If heap expansion fails we set this to
291 // false so that we don't re-attempt the heap expansion (it's likely
292 // that subsequent expansion attempts will also fail if one fails).
293 // Currently, it is only consulted during GC and it's reset at the
294 // start of each GC.
295 bool _expand_heap_after_alloc_failure;
297 // It resets the mutator alloc region before new allocations can take place.
298 void init_mutator_alloc_region();
300 // It releases the mutator alloc region.
301 void release_mutator_alloc_region();
303 // It initializes the GC alloc regions at the start of a GC.
304 void init_gc_alloc_regions();
306 // It releases the GC alloc regions at the end of a GC.
307 void release_gc_alloc_regions();
309 // It does any cleanup that needs to be done on the GC alloc regions
310 // before a Full GC.
311 void abandon_gc_alloc_regions();
313 // Helper for monitoring and management support.
314 G1MonitoringSupport* _g1mm;
316 // Determines PLAB size for a particular allocation purpose.
317 static size_t desired_plab_sz(GCAllocPurpose purpose);
319 // Outside of GC pauses, the number of bytes used in all regions other
320 // than the current allocation region.
321 size_t _summary_bytes_used;
323 // This is used for a quick test on whether a reference points into
324 // the collection set or not. Basically, we have an array, with one
325 // byte per region, and that byte denotes whether the corresponding
326 // region is in the collection set or not. The entry corresponding
327 // the bottom of the heap, i.e., region 0, is pointed to by
328 // _in_cset_fast_test_base. The _in_cset_fast_test field has been
329 // biased so that it actually points to address 0 of the address
330 // space, to make the test as fast as possible (we can simply shift
331 // the address to address into it, instead of having to subtract the
332 // bottom of the heap from the address before shifting it; basically
333 // it works in the same way the card table works).
334 bool* _in_cset_fast_test;
336 // The allocated array used for the fast test on whether a reference
337 // points into the collection set or not. This field is also used to
338 // free the array.
339 bool* _in_cset_fast_test_base;
341 // The length of the _in_cset_fast_test_base array.
342 uint _in_cset_fast_test_length;
344 volatile unsigned _gc_time_stamp;
346 size_t* _surviving_young_words;
348 G1HRPrinter _hr_printer;
350 void setup_surviving_young_words();
351 void update_surviving_young_words(size_t* surv_young_words);
352 void cleanup_surviving_young_words();
354 // It decides whether an explicit GC should start a concurrent cycle
355 // instead of doing a STW GC. Currently, a concurrent cycle is
356 // explicitly started if:
357 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
358 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
359 // (c) cause == _g1_humongous_allocation
360 bool should_do_concurrent_full_gc(GCCause::Cause cause);
362 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
363 // concurrent cycles) we have started.
364 volatile unsigned int _old_marking_cycles_started;
366 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
367 // concurrent cycles) we have completed.
368 volatile unsigned int _old_marking_cycles_completed;
370 // This is a non-product method that is helpful for testing. It is
371 // called at the end of a GC and artificially expands the heap by
372 // allocating a number of dead regions. This way we can induce very
373 // frequent marking cycles and stress the cleanup / concurrent
374 // cleanup code more (as all the regions that will be allocated by
375 // this method will be found dead by the marking cycle).
376 void allocate_dummy_regions() PRODUCT_RETURN;
378 // These are macros so that, if the assert fires, we get the correct
379 // line number, file, etc.
381 #define heap_locking_asserts_err_msg(_extra_message_) \
382 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
383 (_extra_message_), \
384 BOOL_TO_STR(Heap_lock->owned_by_self()), \
385 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
386 BOOL_TO_STR(Thread::current()->is_VM_thread()))
388 #define assert_heap_locked() \
389 do { \
390 assert(Heap_lock->owned_by_self(), \
391 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
392 } while (0)
394 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
395 do { \
396 assert(Heap_lock->owned_by_self() || \
397 (SafepointSynchronize::is_at_safepoint() && \
398 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
399 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
400 "should be at a safepoint")); \
401 } while (0)
403 #define assert_heap_locked_and_not_at_safepoint() \
404 do { \
405 assert(Heap_lock->owned_by_self() && \
406 !SafepointSynchronize::is_at_safepoint(), \
407 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
408 "should not be at a safepoint")); \
409 } while (0)
411 #define assert_heap_not_locked() \
412 do { \
413 assert(!Heap_lock->owned_by_self(), \
414 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
415 } while (0)
417 #define assert_heap_not_locked_and_not_at_safepoint() \
418 do { \
419 assert(!Heap_lock->owned_by_self() && \
420 !SafepointSynchronize::is_at_safepoint(), \
421 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
422 "should not be at a safepoint")); \
423 } while (0)
425 #define assert_at_safepoint(_should_be_vm_thread_) \
426 do { \
427 assert(SafepointSynchronize::is_at_safepoint() && \
428 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
429 heap_locking_asserts_err_msg("should be at a safepoint")); \
430 } while (0)
432 #define assert_not_at_safepoint() \
433 do { \
434 assert(!SafepointSynchronize::is_at_safepoint(), \
435 heap_locking_asserts_err_msg("should not be at a safepoint")); \
436 } while (0)
438 protected:
440 // The young region list.
441 YoungList* _young_list;
443 // The current policy object for the collector.
444 G1CollectorPolicy* _g1_policy;
446 // This is the second level of trying to allocate a new region. If
447 // new_region() didn't find a region on the free_list, this call will
448 // check whether there's anything available on the
449 // secondary_free_list and/or wait for more regions to appear on
450 // that list, if _free_regions_coming is set.
451 HeapRegion* new_region_try_secondary_free_list();
453 // Try to allocate a single non-humongous HeapRegion sufficient for
454 // an allocation of the given word_size. If do_expand is true,
455 // attempt to expand the heap if necessary to satisfy the allocation
456 // request.
457 HeapRegion* new_region(size_t word_size, bool do_expand);
459 // Attempt to satisfy a humongous allocation request of the given
460 // size by finding a contiguous set of free regions of num_regions
461 // length and remove them from the master free list. Return the
462 // index of the first region or G1_NULL_HRS_INDEX if the search
463 // was unsuccessful.
464 uint humongous_obj_allocate_find_first(uint num_regions,
465 size_t word_size);
467 // Initialize a contiguous set of free regions of length num_regions
468 // and starting at index first so that they appear as a single
469 // humongous region.
470 HeapWord* humongous_obj_allocate_initialize_regions(uint first,
471 uint num_regions,
472 size_t word_size);
474 // Attempt to allocate a humongous object of the given size. Return
475 // NULL if unsuccessful.
476 HeapWord* humongous_obj_allocate(size_t word_size);
478 // The following two methods, allocate_new_tlab() and
479 // mem_allocate(), are the two main entry points from the runtime
480 // into the G1's allocation routines. They have the following
481 // assumptions:
482 //
483 // * They should both be called outside safepoints.
484 //
485 // * They should both be called without holding the Heap_lock.
486 //
487 // * All allocation requests for new TLABs should go to
488 // allocate_new_tlab().
489 //
490 // * All non-TLAB allocation requests should go to mem_allocate().
491 //
492 // * If either call cannot satisfy the allocation request using the
493 // current allocating region, they will try to get a new one. If
494 // this fails, they will attempt to do an evacuation pause and
495 // retry the allocation.
496 //
497 // * If all allocation attempts fail, even after trying to schedule
498 // an evacuation pause, allocate_new_tlab() will return NULL,
499 // whereas mem_allocate() will attempt a heap expansion and/or
500 // schedule a Full GC.
501 //
502 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
503 // should never be called with word_size being humongous. All
504 // humongous allocation requests should go to mem_allocate() which
505 // will satisfy them with a special path.
507 virtual HeapWord* allocate_new_tlab(size_t word_size);
509 virtual HeapWord* mem_allocate(size_t word_size,
510 bool* gc_overhead_limit_was_exceeded);
512 // The following three methods take a gc_count_before_ret
513 // parameter which is used to return the GC count if the method
514 // returns NULL. Given that we are required to read the GC count
515 // while holding the Heap_lock, and these paths will take the
516 // Heap_lock at some point, it's easier to get them to read the GC
517 // count while holding the Heap_lock before they return NULL instead
518 // of the caller (namely: mem_allocate()) having to also take the
519 // Heap_lock just to read the GC count.
521 // First-level mutator allocation attempt: try to allocate out of
522 // the mutator alloc region without taking the Heap_lock. This
523 // should only be used for non-humongous allocations.
524 inline HeapWord* attempt_allocation(size_t word_size,
525 unsigned int* gc_count_before_ret);
527 // Second-level mutator allocation attempt: take the Heap_lock and
528 // retry the allocation attempt, potentially scheduling a GC
529 // pause. This should only be used for non-humongous allocations.
530 HeapWord* attempt_allocation_slow(size_t word_size,
531 unsigned int* gc_count_before_ret);
533 // Takes the Heap_lock and attempts a humongous allocation. It can
534 // potentially schedule a GC pause.
535 HeapWord* attempt_allocation_humongous(size_t word_size,
536 unsigned int* gc_count_before_ret);
538 // Allocation attempt that should be called during safepoints (e.g.,
539 // at the end of a successful GC). expect_null_mutator_alloc_region
540 // specifies whether the mutator alloc region is expected to be NULL
541 // or not.
542 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
543 bool expect_null_mutator_alloc_region);
545 // It dirties the cards that cover the block so that so that the post
546 // write barrier never queues anything when updating objects on this
547 // block. It is assumed (and in fact we assert) that the block
548 // belongs to a young region.
549 inline void dirty_young_block(HeapWord* start, size_t word_size);
551 // Allocate blocks during garbage collection. Will ensure an
552 // allocation region, either by picking one or expanding the
553 // heap, and then allocate a block of the given size. The block
554 // may not be a humongous - it must fit into a single heap region.
555 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size);
557 HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose,
558 HeapRegion* alloc_region,
559 bool par,
560 size_t word_size);
562 // Ensure that no further allocations can happen in "r", bearing in mind
563 // that parallel threads might be attempting allocations.
564 void par_allocate_remaining_space(HeapRegion* r);
566 // Allocation attempt during GC for a survivor object / PLAB.
567 inline HeapWord* survivor_attempt_allocation(size_t word_size);
569 // Allocation attempt during GC for an old object / PLAB.
570 inline HeapWord* old_attempt_allocation(size_t word_size);
572 // These methods are the "callbacks" from the G1AllocRegion class.
574 // For mutator alloc regions.
575 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
576 void retire_mutator_alloc_region(HeapRegion* alloc_region,
577 size_t allocated_bytes);
579 // For GC alloc regions.
580 HeapRegion* new_gc_alloc_region(size_t word_size, uint count,
581 GCAllocPurpose ap);
582 void retire_gc_alloc_region(HeapRegion* alloc_region,
583 size_t allocated_bytes, GCAllocPurpose ap);
585 // - if explicit_gc is true, the GC is for a System.gc() or a heap
586 // inspection request and should collect the entire heap
587 // - if clear_all_soft_refs is true, all soft references should be
588 // cleared during the GC
589 // - if explicit_gc is false, word_size describes the allocation that
590 // the GC should attempt (at least) to satisfy
591 // - it returns false if it is unable to do the collection due to the
592 // GC locker being active, true otherwise
593 bool do_collection(bool explicit_gc,
594 bool clear_all_soft_refs,
595 size_t word_size);
597 // Callback from VM_G1CollectFull operation.
598 // Perform a full collection.
599 void do_full_collection(bool clear_all_soft_refs);
601 // Resize the heap if necessary after a full collection. If this is
602 // after a collect-for allocation, "word_size" is the allocation size,
603 // and will be considered part of the used portion of the heap.
604 void resize_if_necessary_after_full_collection(size_t word_size);
606 // Callback from VM_G1CollectForAllocation operation.
607 // This function does everything necessary/possible to satisfy a
608 // failed allocation request (including collection, expansion, etc.)
609 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded);
611 // Attempting to expand the heap sufficiently
612 // to support an allocation of the given "word_size". If
613 // successful, perform the allocation and return the address of the
614 // allocated block, or else "NULL".
615 HeapWord* expand_and_allocate(size_t word_size);
617 // Process any reference objects discovered during
618 // an incremental evacuation pause.
619 void process_discovered_references();
621 // Enqueue any remaining discovered references
622 // after processing.
623 void enqueue_discovered_references();
625 public:
627 G1MonitoringSupport* g1mm() {
628 assert(_g1mm != NULL, "should have been initialized");
629 return _g1mm;
630 }
632 // Expand the garbage-first heap by at least the given size (in bytes!).
633 // Returns true if the heap was expanded by the requested amount;
634 // false otherwise.
635 // (Rounds up to a HeapRegion boundary.)
636 bool expand(size_t expand_bytes);
638 // Do anything common to GC's.
639 virtual void gc_prologue(bool full);
640 virtual void gc_epilogue(bool full);
642 // We register a region with the fast "in collection set" test. We
643 // simply set to true the array slot corresponding to this region.
644 void register_region_with_in_cset_fast_test(HeapRegion* r) {
645 assert(_in_cset_fast_test_base != NULL, "sanity");
646 assert(r->in_collection_set(), "invariant");
647 uint index = r->hrs_index();
648 assert(index < _in_cset_fast_test_length, "invariant");
649 assert(!_in_cset_fast_test_base[index], "invariant");
650 _in_cset_fast_test_base[index] = true;
651 }
653 // This is a fast test on whether a reference points into the
654 // collection set or not. It does not assume that the reference
655 // points into the heap; if it doesn't, it will return false.
656 bool in_cset_fast_test(oop obj) {
657 assert(_in_cset_fast_test != NULL, "sanity");
658 if (_g1_committed.contains((HeapWord*) obj)) {
659 // no need to subtract the bottom of the heap from obj,
660 // _in_cset_fast_test is biased
661 uintx index = (uintx) obj >> HeapRegion::LogOfHRGrainBytes;
662 bool ret = _in_cset_fast_test[index];
663 // let's make sure the result is consistent with what the slower
664 // test returns
665 assert( ret || !obj_in_cs(obj), "sanity");
666 assert(!ret || obj_in_cs(obj), "sanity");
667 return ret;
668 } else {
669 return false;
670 }
671 }
673 void clear_cset_fast_test() {
674 assert(_in_cset_fast_test_base != NULL, "sanity");
675 memset(_in_cset_fast_test_base, false,
676 (size_t) _in_cset_fast_test_length * sizeof(bool));
677 }
679 // This is called at the start of either a concurrent cycle or a Full
680 // GC to update the number of old marking cycles started.
681 void increment_old_marking_cycles_started();
683 // This is called at the end of either a concurrent cycle or a Full
684 // GC to update the number of old marking cycles completed. Those two
685 // can happen in a nested fashion, i.e., we start a concurrent
686 // cycle, a Full GC happens half-way through it which ends first,
687 // and then the cycle notices that a Full GC happened and ends
688 // too. The concurrent parameter is a boolean to help us do a bit
689 // tighter consistency checking in the method. If concurrent is
690 // false, the caller is the inner caller in the nesting (i.e., the
691 // Full GC). If concurrent is true, the caller is the outer caller
692 // in this nesting (i.e., the concurrent cycle). Further nesting is
693 // not currently supported. The end of this call also notifies
694 // the FullGCCount_lock in case a Java thread is waiting for a full
695 // GC to happen (e.g., it called System.gc() with
696 // +ExplicitGCInvokesConcurrent).
697 void increment_old_marking_cycles_completed(bool concurrent);
699 unsigned int old_marking_cycles_completed() {
700 return _old_marking_cycles_completed;
701 }
703 G1HRPrinter* hr_printer() { return &_hr_printer; }
705 protected:
707 // Shrink the garbage-first heap by at most the given size (in bytes!).
708 // (Rounds down to a HeapRegion boundary.)
709 virtual void shrink(size_t expand_bytes);
710 void shrink_helper(size_t expand_bytes);
712 #if TASKQUEUE_STATS
713 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
714 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
715 void reset_taskqueue_stats();
716 #endif // TASKQUEUE_STATS
718 // Schedule the VM operation that will do an evacuation pause to
719 // satisfy an allocation request of word_size. *succeeded will
720 // return whether the VM operation was successful (it did do an
721 // evacuation pause) or not (another thread beat us to it or the GC
722 // locker was active). Given that we should not be holding the
723 // Heap_lock when we enter this method, we will pass the
724 // gc_count_before (i.e., total_collections()) as a parameter since
725 // it has to be read while holding the Heap_lock. Currently, both
726 // methods that call do_collection_pause() release the Heap_lock
727 // before the call, so it's easy to read gc_count_before just before.
728 HeapWord* do_collection_pause(size_t word_size,
729 unsigned int gc_count_before,
730 bool* succeeded);
732 // The guts of the incremental collection pause, executed by the vm
733 // thread. It returns false if it is unable to do the collection due
734 // to the GC locker being active, true otherwise
735 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
737 // Actually do the work of evacuating the collection set.
738 void evacuate_collection_set();
740 // The g1 remembered set of the heap.
741 G1RemSet* _g1_rem_set;
742 // And it's mod ref barrier set, used to track updates for the above.
743 ModRefBarrierSet* _mr_bs;
745 // A set of cards that cover the objects for which the Rsets should be updated
746 // concurrently after the collection.
747 DirtyCardQueueSet _dirty_card_queue_set;
749 // The Heap Region Rem Set Iterator.
750 HeapRegionRemSetIterator** _rem_set_iterator;
752 // The closure used to refine a single card.
753 RefineCardTableEntryClosure* _refine_cte_cl;
755 // A function to check the consistency of dirty card logs.
756 void check_ct_logs_at_safepoint();
758 // A DirtyCardQueueSet that is used to hold cards that contain
759 // references into the current collection set. This is used to
760 // update the remembered sets of the regions in the collection
761 // set in the event of an evacuation failure.
762 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
764 // After a collection pause, make the regions in the CS into free
765 // regions.
766 void free_collection_set(HeapRegion* cs_head);
768 // Abandon the current collection set without recording policy
769 // statistics or updating free lists.
770 void abandon_collection_set(HeapRegion* cs_head);
772 // Applies "scan_non_heap_roots" to roots outside the heap,
773 // "scan_rs" to roots inside the heap (having done "set_region" to
774 // indicate the region in which the root resides), and does "scan_perm"
775 // (setting the generation to the perm generation.) If "scan_rs" is
776 // NULL, then this step is skipped. The "worker_i"
777 // param is for use with parallel roots processing, and should be
778 // the "i" of the calling parallel worker thread's work(i) function.
779 // In the sequential case this param will be ignored.
780 void g1_process_strong_roots(bool collecting_perm_gen,
781 ScanningOption so,
782 OopClosure* scan_non_heap_roots,
783 OopsInHeapRegionClosure* scan_rs,
784 OopsInGenClosure* scan_perm,
785 int worker_i);
787 // Apply "blk" to all the weak roots of the system. These include
788 // JNI weak roots, the code cache, system dictionary, symbol table,
789 // string table, and referents of reachable weak refs.
790 void g1_process_weak_roots(OopClosure* root_closure,
791 OopClosure* non_root_closure);
793 // Frees a non-humongous region by initializing its contents and
794 // adding it to the free list that's passed as a parameter (this is
795 // usually a local list which will be appended to the master free
796 // list later). The used bytes of freed regions are accumulated in
797 // pre_used. If par is true, the region's RSet will not be freed
798 // up. The assumption is that this will be done later.
799 void free_region(HeapRegion* hr,
800 size_t* pre_used,
801 FreeRegionList* free_list,
802 bool par);
804 // Frees a humongous region by collapsing it into individual regions
805 // and calling free_region() for each of them. The freed regions
806 // will be added to the free list that's passed as a parameter (this
807 // is usually a local list which will be appended to the master free
808 // list later). The used bytes of freed regions are accumulated in
809 // pre_used. If par is true, the region's RSet will not be freed
810 // up. The assumption is that this will be done later.
811 void free_humongous_region(HeapRegion* hr,
812 size_t* pre_used,
813 FreeRegionList* free_list,
814 HumongousRegionSet* humongous_proxy_set,
815 bool par);
817 // Notifies all the necessary spaces that the committed space has
818 // been updated (either expanded or shrunk). It should be called
819 // after _g1_storage is updated.
820 void update_committed_space(HeapWord* old_end, HeapWord* new_end);
822 // The concurrent marker (and the thread it runs in.)
823 ConcurrentMark* _cm;
824 ConcurrentMarkThread* _cmThread;
825 bool _mark_in_progress;
827 // The concurrent refiner.
828 ConcurrentG1Refine* _cg1r;
830 // The parallel task queues
831 RefToScanQueueSet *_task_queues;
833 // True iff a evacuation has failed in the current collection.
834 bool _evacuation_failed;
836 // Set the attribute indicating whether evacuation has failed in the
837 // current collection.
838 void set_evacuation_failed(bool b) { _evacuation_failed = b; }
840 // Failed evacuations cause some logical from-space objects to have
841 // forwarding pointers to themselves. Reset them.
842 void remove_self_forwarding_pointers();
844 // When one is non-null, so is the other. Together, they each pair is
845 // an object with a preserved mark, and its mark value.
846 GrowableArray<oop>* _objs_with_preserved_marks;
847 GrowableArray<markOop>* _preserved_marks_of_objs;
849 // Preserve the mark of "obj", if necessary, in preparation for its mark
850 // word being overwritten with a self-forwarding-pointer.
851 void preserve_mark_if_necessary(oop obj, markOop m);
853 // The stack of evac-failure objects left to be scanned.
854 GrowableArray<oop>* _evac_failure_scan_stack;
855 // The closure to apply to evac-failure objects.
857 OopsInHeapRegionClosure* _evac_failure_closure;
858 // Set the field above.
859 void
860 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
861 _evac_failure_closure = evac_failure_closure;
862 }
864 // Push "obj" on the scan stack.
865 void push_on_evac_failure_scan_stack(oop obj);
866 // Process scan stack entries until the stack is empty.
867 void drain_evac_failure_scan_stack();
868 // True iff an invocation of "drain_scan_stack" is in progress; to
869 // prevent unnecessary recursion.
870 bool _drain_in_progress;
872 // Do any necessary initialization for evacuation-failure handling.
873 // "cl" is the closure that will be used to process evac-failure
874 // objects.
875 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
876 // Do any necessary cleanup for evacuation-failure handling data
877 // structures.
878 void finalize_for_evac_failure();
880 // An attempt to evacuate "obj" has failed; take necessary steps.
881 oop handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, oop obj);
882 void handle_evacuation_failure_common(oop obj, markOop m);
884 // ("Weak") Reference processing support.
885 //
886 // G1 has 2 instances of the referece processor class. One
887 // (_ref_processor_cm) handles reference object discovery
888 // and subsequent processing during concurrent marking cycles.
889 //
890 // The other (_ref_processor_stw) handles reference object
891 // discovery and processing during full GCs and incremental
892 // evacuation pauses.
893 //
894 // During an incremental pause, reference discovery will be
895 // temporarily disabled for _ref_processor_cm and will be
896 // enabled for _ref_processor_stw. At the end of the evacuation
897 // pause references discovered by _ref_processor_stw will be
898 // processed and discovery will be disabled. The previous
899 // setting for reference object discovery for _ref_processor_cm
900 // will be re-instated.
901 //
902 // At the start of marking:
903 // * Discovery by the CM ref processor is verified to be inactive
904 // and it's discovered lists are empty.
905 // * Discovery by the CM ref processor is then enabled.
906 //
907 // At the end of marking:
908 // * Any references on the CM ref processor's discovered
909 // lists are processed (possibly MT).
910 //
911 // At the start of full GC we:
912 // * Disable discovery by the CM ref processor and
913 // empty CM ref processor's discovered lists
914 // (without processing any entries).
915 // * Verify that the STW ref processor is inactive and it's
916 // discovered lists are empty.
917 // * Temporarily set STW ref processor discovery as single threaded.
918 // * Temporarily clear the STW ref processor's _is_alive_non_header
919 // field.
920 // * Finally enable discovery by the STW ref processor.
921 //
922 // The STW ref processor is used to record any discovered
923 // references during the full GC.
924 //
925 // At the end of a full GC we:
926 // * Enqueue any reference objects discovered by the STW ref processor
927 // that have non-live referents. This has the side-effect of
928 // making the STW ref processor inactive by disabling discovery.
929 // * Verify that the CM ref processor is still inactive
930 // and no references have been placed on it's discovered
931 // lists (also checked as a precondition during initial marking).
933 // The (stw) reference processor...
934 ReferenceProcessor* _ref_processor_stw;
936 // During reference object discovery, the _is_alive_non_header
937 // closure (if non-null) is applied to the referent object to
938 // determine whether the referent is live. If so then the
939 // reference object does not need to be 'discovered' and can
940 // be treated as a regular oop. This has the benefit of reducing
941 // the number of 'discovered' reference objects that need to
942 // be processed.
943 //
944 // Instance of the is_alive closure for embedding into the
945 // STW reference processor as the _is_alive_non_header field.
946 // Supplying a value for the _is_alive_non_header field is
947 // optional but doing so prevents unnecessary additions to
948 // the discovered lists during reference discovery.
949 G1STWIsAliveClosure _is_alive_closure_stw;
951 // The (concurrent marking) reference processor...
952 ReferenceProcessor* _ref_processor_cm;
954 // Instance of the concurrent mark is_alive closure for embedding
955 // into the Concurrent Marking reference processor as the
956 // _is_alive_non_header field. Supplying a value for the
957 // _is_alive_non_header field is optional but doing so prevents
958 // unnecessary additions to the discovered lists during reference
959 // discovery.
960 G1CMIsAliveClosure _is_alive_closure_cm;
962 // Cache used by G1CollectedHeap::start_cset_region_for_worker().
963 HeapRegion** _worker_cset_start_region;
965 // Time stamp to validate the regions recorded in the cache
966 // used by G1CollectedHeap::start_cset_region_for_worker().
967 // The heap region entry for a given worker is valid iff
968 // the associated time stamp value matches the current value
969 // of G1CollectedHeap::_gc_time_stamp.
970 unsigned int* _worker_cset_start_region_time_stamp;
972 enum G1H_process_strong_roots_tasks {
973 G1H_PS_filter_satb_buffers,
974 G1H_PS_refProcessor_oops_do,
975 // Leave this one last.
976 G1H_PS_NumElements
977 };
979 SubTasksDone* _process_strong_tasks;
981 volatile bool _free_regions_coming;
983 public:
985 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
987 void set_refine_cte_cl_concurrency(bool concurrent);
989 RefToScanQueue *task_queue(int i) const;
991 // A set of cards where updates happened during the GC
992 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
994 // A DirtyCardQueueSet that is used to hold cards that contain
995 // references into the current collection set. This is used to
996 // update the remembered sets of the regions in the collection
997 // set in the event of an evacuation failure.
998 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
999 { return _into_cset_dirty_card_queue_set; }
1001 // Create a G1CollectedHeap with the specified policy.
1002 // Must call the initialize method afterwards.
1003 // May not return if something goes wrong.
1004 G1CollectedHeap(G1CollectorPolicy* policy);
1006 // Initialize the G1CollectedHeap to have the initial and
1007 // maximum sizes, permanent generation, and remembered and barrier sets
1008 // specified by the policy object.
1009 jint initialize();
1011 // Initialize weak reference processing.
1012 virtual void ref_processing_init();
1014 void set_par_threads(uint t) {
1015 SharedHeap::set_par_threads(t);
1016 // Done in SharedHeap but oddly there are
1017 // two _process_strong_tasks's in a G1CollectedHeap
1018 // so do it here too.
1019 _process_strong_tasks->set_n_threads(t);
1020 }
1022 // Set _n_par_threads according to a policy TBD.
1023 void set_par_threads();
1025 void set_n_termination(int t) {
1026 _process_strong_tasks->set_n_threads(t);
1027 }
1029 virtual CollectedHeap::Name kind() const {
1030 return CollectedHeap::G1CollectedHeap;
1031 }
1033 // The current policy object for the collector.
1034 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
1036 // Adaptive size policy. No such thing for g1.
1037 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
1039 // The rem set and barrier set.
1040 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
1041 ModRefBarrierSet* mr_bs() const { return _mr_bs; }
1043 // The rem set iterator.
1044 HeapRegionRemSetIterator* rem_set_iterator(int i) {
1045 return _rem_set_iterator[i];
1046 }
1048 HeapRegionRemSetIterator* rem_set_iterator() {
1049 return _rem_set_iterator[0];
1050 }
1052 unsigned get_gc_time_stamp() {
1053 return _gc_time_stamp;
1054 }
1056 void reset_gc_time_stamp() {
1057 _gc_time_stamp = 0;
1058 OrderAccess::fence();
1059 // Clear the cached CSet starting regions and time stamps.
1060 // Their validity is dependent on the GC timestamp.
1061 clear_cset_start_regions();
1062 }
1064 void increment_gc_time_stamp() {
1065 ++_gc_time_stamp;
1066 OrderAccess::fence();
1067 }
1069 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
1070 DirtyCardQueue* into_cset_dcq,
1071 bool concurrent, int worker_i);
1073 // The shared block offset table array.
1074 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
1076 // Reference Processing accessors
1078 // The STW reference processor....
1079 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1081 // The Concurent Marking reference processor...
1082 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1084 virtual size_t capacity() const;
1085 virtual size_t used() const;
1086 // This should be called when we're not holding the heap lock. The
1087 // result might be a bit inaccurate.
1088 size_t used_unlocked() const;
1089 size_t recalculate_used() const;
1091 // These virtual functions do the actual allocation.
1092 // Some heaps may offer a contiguous region for shared non-blocking
1093 // allocation, via inlined code (by exporting the address of the top and
1094 // end fields defining the extent of the contiguous allocation region.)
1095 // But G1CollectedHeap doesn't yet support this.
1097 // Return an estimate of the maximum allocation that could be performed
1098 // without triggering any collection or expansion activity. In a
1099 // generational collector, for example, this is probably the largest
1100 // allocation that could be supported (without expansion) in the youngest
1101 // generation. It is "unsafe" because no locks are taken; the result
1102 // should be treated as an approximation, not a guarantee, for use in
1103 // heuristic resizing decisions.
1104 virtual size_t unsafe_max_alloc();
1106 virtual bool is_maximal_no_gc() const {
1107 return _g1_storage.uncommitted_size() == 0;
1108 }
1110 // The total number of regions in the heap.
1111 uint n_regions() { return _hrs.length(); }
1113 // The max number of regions in the heap.
1114 uint max_regions() { return _hrs.max_length(); }
1116 // The number of regions that are completely free.
1117 uint free_regions() { return _free_list.length(); }
1119 // The number of regions that are not completely free.
1120 uint used_regions() { return n_regions() - free_regions(); }
1122 // The number of regions available for "regular" expansion.
1123 uint expansion_regions() { return _expansion_regions; }
1125 // Factory method for HeapRegion instances. It will return NULL if
1126 // the allocation fails.
1127 HeapRegion* new_heap_region(uint hrs_index, HeapWord* bottom);
1129 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1130 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1131 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
1132 void verify_dirty_young_regions() PRODUCT_RETURN;
1134 // verify_region_sets() performs verification over the region
1135 // lists. It will be compiled in the product code to be used when
1136 // necessary (i.e., during heap verification).
1137 void verify_region_sets();
1139 // verify_region_sets_optional() is planted in the code for
1140 // list verification in non-product builds (and it can be enabled in
1141 // product builds by definning HEAP_REGION_SET_FORCE_VERIFY to be 1).
1142 #if HEAP_REGION_SET_FORCE_VERIFY
1143 void verify_region_sets_optional() {
1144 verify_region_sets();
1145 }
1146 #else // HEAP_REGION_SET_FORCE_VERIFY
1147 void verify_region_sets_optional() { }
1148 #endif // HEAP_REGION_SET_FORCE_VERIFY
1150 #ifdef ASSERT
1151 bool is_on_master_free_list(HeapRegion* hr) {
1152 return hr->containing_set() == &_free_list;
1153 }
1155 bool is_in_humongous_set(HeapRegion* hr) {
1156 return hr->containing_set() == &_humongous_set;
1157 }
1158 #endif // ASSERT
1160 // Wrapper for the region list operations that can be called from
1161 // methods outside this class.
1163 void secondary_free_list_add_as_tail(FreeRegionList* list) {
1164 _secondary_free_list.add_as_tail(list);
1165 }
1167 void append_secondary_free_list() {
1168 _free_list.add_as_head(&_secondary_free_list);
1169 }
1171 void append_secondary_free_list_if_not_empty_with_lock() {
1172 // If the secondary free list looks empty there's no reason to
1173 // take the lock and then try to append it.
1174 if (!_secondary_free_list.is_empty()) {
1175 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1176 append_secondary_free_list();
1177 }
1178 }
1180 void old_set_remove(HeapRegion* hr) {
1181 _old_set.remove(hr);
1182 }
1184 size_t non_young_capacity_bytes() {
1185 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes();
1186 }
1188 void set_free_regions_coming();
1189 void reset_free_regions_coming();
1190 bool free_regions_coming() { return _free_regions_coming; }
1191 void wait_while_free_regions_coming();
1193 // Determine whether the given region is one that we are using as an
1194 // old GC alloc region.
1195 bool is_old_gc_alloc_region(HeapRegion* hr) {
1196 return hr == _retained_old_gc_alloc_region;
1197 }
1199 // Perform a collection of the heap; intended for use in implementing
1200 // "System.gc". This probably implies as full a collection as the
1201 // "CollectedHeap" supports.
1202 virtual void collect(GCCause::Cause cause);
1204 // The same as above but assume that the caller holds the Heap_lock.
1205 void collect_locked(GCCause::Cause cause);
1207 // This interface assumes that it's being called by the
1208 // vm thread. It collects the heap assuming that the
1209 // heap lock is already held and that we are executing in
1210 // the context of the vm thread.
1211 virtual void collect_as_vm_thread(GCCause::Cause cause);
1213 // True iff a evacuation has failed in the most-recent collection.
1214 bool evacuation_failed() { return _evacuation_failed; }
1216 // It will free a region if it has allocated objects in it that are
1217 // all dead. It calls either free_region() or
1218 // free_humongous_region() depending on the type of the region that
1219 // is passed to it.
1220 void free_region_if_empty(HeapRegion* hr,
1221 size_t* pre_used,
1222 FreeRegionList* free_list,
1223 OldRegionSet* old_proxy_set,
1224 HumongousRegionSet* humongous_proxy_set,
1225 HRRSCleanupTask* hrrs_cleanup_task,
1226 bool par);
1228 // It appends the free list to the master free list and updates the
1229 // master humongous list according to the contents of the proxy
1230 // list. It also adjusts the total used bytes according to pre_used
1231 // (if par is true, it will do so by taking the ParGCRareEvent_lock).
1232 void update_sets_after_freeing_regions(size_t pre_used,
1233 FreeRegionList* free_list,
1234 OldRegionSet* old_proxy_set,
1235 HumongousRegionSet* humongous_proxy_set,
1236 bool par);
1238 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1239 virtual bool is_in(const void* p) const;
1241 // Return "TRUE" iff the given object address is within the collection
1242 // set.
1243 inline bool obj_in_cs(oop obj);
1245 // Return "TRUE" iff the given object address is in the reserved
1246 // region of g1 (excluding the permanent generation).
1247 bool is_in_g1_reserved(const void* p) const {
1248 return _g1_reserved.contains(p);
1249 }
1251 // Returns a MemRegion that corresponds to the space that has been
1252 // reserved for the heap
1253 MemRegion g1_reserved() {
1254 return _g1_reserved;
1255 }
1257 // Returns a MemRegion that corresponds to the space that has been
1258 // committed in the heap
1259 MemRegion g1_committed() {
1260 return _g1_committed;
1261 }
1263 virtual bool is_in_closed_subset(const void* p) const;
1265 // This resets the card table to all zeros. It is used after
1266 // a collection pause which used the card table to claim cards.
1267 void cleanUpCardTable();
1269 // Iteration functions.
1271 // Iterate over all the ref-containing fields of all objects, calling
1272 // "cl.do_oop" on each.
1273 virtual void oop_iterate(OopClosure* cl) {
1274 oop_iterate(cl, true);
1275 }
1276 void oop_iterate(OopClosure* cl, bool do_perm);
1278 // Same as above, restricted to a memory region.
1279 virtual void oop_iterate(MemRegion mr, OopClosure* cl) {
1280 oop_iterate(mr, cl, true);
1281 }
1282 void oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm);
1284 // Iterate over all objects, calling "cl.do_object" on each.
1285 virtual void object_iterate(ObjectClosure* cl) {
1286 object_iterate(cl, true);
1287 }
1288 virtual void safe_object_iterate(ObjectClosure* cl) {
1289 object_iterate(cl, true);
1290 }
1291 void object_iterate(ObjectClosure* cl, bool do_perm);
1293 // Iterate over all objects allocated since the last collection, calling
1294 // "cl.do_object" on each. The heap must have been initialized properly
1295 // to support this function, or else this call will fail.
1296 virtual void object_iterate_since_last_GC(ObjectClosure* cl);
1298 // Iterate over all spaces in use in the heap, in ascending address order.
1299 virtual void space_iterate(SpaceClosure* cl);
1301 // Iterate over heap regions, in address order, terminating the
1302 // iteration early if the "doHeapRegion" method returns "true".
1303 void heap_region_iterate(HeapRegionClosure* blk) const;
1305 // Iterate over heap regions starting with r (or the first region if "r"
1306 // is NULL), in address order, terminating early if the "doHeapRegion"
1307 // method returns "true".
1308 void heap_region_iterate_from(HeapRegion* r, HeapRegionClosure* blk) const;
1310 // Return the region with the given index. It assumes the index is valid.
1311 HeapRegion* region_at(uint index) const { return _hrs.at(index); }
1313 // Divide the heap region sequence into "chunks" of some size (the number
1314 // of regions divided by the number of parallel threads times some
1315 // overpartition factor, currently 4). Assumes that this will be called
1316 // in parallel by ParallelGCThreads worker threads with discinct worker
1317 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
1318 // calls will use the same "claim_value", and that that claim value is
1319 // different from the claim_value of any heap region before the start of
1320 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by
1321 // attempting to claim the first region in each chunk, and, if
1322 // successful, applying the closure to each region in the chunk (and
1323 // setting the claim value of the second and subsequent regions of the
1324 // chunk.) For now requires that "doHeapRegion" always returns "false",
1325 // i.e., that a closure never attempt to abort a traversal.
1326 void heap_region_par_iterate_chunked(HeapRegionClosure* blk,
1327 uint worker,
1328 uint no_of_par_workers,
1329 jint claim_value);
1331 // It resets all the region claim values to the default.
1332 void reset_heap_region_claim_values();
1334 // Resets the claim values of regions in the current
1335 // collection set to the default.
1336 void reset_cset_heap_region_claim_values();
1338 #ifdef ASSERT
1339 bool check_heap_region_claim_values(jint claim_value);
1341 // Same as the routine above but only checks regions in the
1342 // current collection set.
1343 bool check_cset_heap_region_claim_values(jint claim_value);
1344 #endif // ASSERT
1346 // Clear the cached cset start regions and (more importantly)
1347 // the time stamps. Called when we reset the GC time stamp.
1348 void clear_cset_start_regions();
1350 // Given the id of a worker, obtain or calculate a suitable
1351 // starting region for iterating over the current collection set.
1352 HeapRegion* start_cset_region_for_worker(int worker_i);
1354 // Iterate over the regions (if any) in the current collection set.
1355 void collection_set_iterate(HeapRegionClosure* blk);
1357 // As above but starting from region r
1358 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1360 // Returns the first (lowest address) compactible space in the heap.
1361 virtual CompactibleSpace* first_compactible_space();
1363 // A CollectedHeap will contain some number of spaces. This finds the
1364 // space containing a given address, or else returns NULL.
1365 virtual Space* space_containing(const void* addr) const;
1367 // A G1CollectedHeap will contain some number of heap regions. This
1368 // finds the region containing a given address, or else returns NULL.
1369 template <class T>
1370 inline HeapRegion* heap_region_containing(const T addr) const;
1372 // Like the above, but requires "addr" to be in the heap (to avoid a
1373 // null-check), and unlike the above, may return an continuing humongous
1374 // region.
1375 template <class T>
1376 inline HeapRegion* heap_region_containing_raw(const T addr) const;
1378 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1379 // each address in the (reserved) heap is a member of exactly
1380 // one block. The defining characteristic of a block is that it is
1381 // possible to find its size, and thus to progress forward to the next
1382 // block. (Blocks may be of different sizes.) Thus, blocks may
1383 // represent Java objects, or they might be free blocks in a
1384 // free-list-based heap (or subheap), as long as the two kinds are
1385 // distinguishable and the size of each is determinable.
1387 // Returns the address of the start of the "block" that contains the
1388 // address "addr". We say "blocks" instead of "object" since some heaps
1389 // may not pack objects densely; a chunk may either be an object or a
1390 // non-object.
1391 virtual HeapWord* block_start(const void* addr) const;
1393 // Requires "addr" to be the start of a chunk, and returns its size.
1394 // "addr + size" is required to be the start of a new chunk, or the end
1395 // of the active area of the heap.
1396 virtual size_t block_size(const HeapWord* addr) const;
1398 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1399 // the block is an object.
1400 virtual bool block_is_obj(const HeapWord* addr) const;
1402 // Does this heap support heap inspection? (+PrintClassHistogram)
1403 virtual bool supports_heap_inspection() const { return true; }
1405 // Section on thread-local allocation buffers (TLABs)
1406 // See CollectedHeap for semantics.
1408 virtual bool supports_tlab_allocation() const;
1409 virtual size_t tlab_capacity(Thread* thr) const;
1410 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
1412 // Can a compiler initialize a new object without store barriers?
1413 // This permission only extends from the creation of a new object
1414 // via a TLAB up to the first subsequent safepoint. If such permission
1415 // is granted for this heap type, the compiler promises to call
1416 // defer_store_barrier() below on any slow path allocation of
1417 // a new object for which such initializing store barriers will
1418 // have been elided. G1, like CMS, allows this, but should be
1419 // ready to provide a compensating write barrier as necessary
1420 // if that storage came out of a non-young region. The efficiency
1421 // of this implementation depends crucially on being able to
1422 // answer very efficiently in constant time whether a piece of
1423 // storage in the heap comes from a young region or not.
1424 // See ReduceInitialCardMarks.
1425 virtual bool can_elide_tlab_store_barriers() const {
1426 return true;
1427 }
1429 virtual bool card_mark_must_follow_store() const {
1430 return true;
1431 }
1433 bool is_in_young(const oop obj) {
1434 HeapRegion* hr = heap_region_containing(obj);
1435 return hr != NULL && hr->is_young();
1436 }
1438 #ifdef ASSERT
1439 virtual bool is_in_partial_collection(const void* p);
1440 #endif
1442 virtual bool is_scavengable(const void* addr);
1444 // We don't need barriers for initializing stores to objects
1445 // in the young gen: for the SATB pre-barrier, there is no
1446 // pre-value that needs to be remembered; for the remembered-set
1447 // update logging post-barrier, we don't maintain remembered set
1448 // information for young gen objects.
1449 virtual bool can_elide_initializing_store_barrier(oop new_obj) {
1450 return is_in_young(new_obj);
1451 }
1453 // Can a compiler elide a store barrier when it writes
1454 // a permanent oop into the heap? Applies when the compiler
1455 // is storing x to the heap, where x->is_perm() is true.
1456 virtual bool can_elide_permanent_oop_store_barriers() const {
1457 // At least until perm gen collection is also G1-ified, at
1458 // which point this should return false.
1459 return true;
1460 }
1462 // Returns "true" iff the given word_size is "very large".
1463 static bool isHumongous(size_t word_size) {
1464 // Note this has to be strictly greater-than as the TLABs
1465 // are capped at the humongous thresold and we want to
1466 // ensure that we don't try to allocate a TLAB as
1467 // humongous and that we don't allocate a humongous
1468 // object in a TLAB.
1469 return word_size > _humongous_object_threshold_in_words;
1470 }
1472 // Update mod union table with the set of dirty cards.
1473 void updateModUnion();
1475 // Set the mod union bits corresponding to the given memRegion. Note
1476 // that this is always a safe operation, since it doesn't clear any
1477 // bits.
1478 void markModUnionRange(MemRegion mr);
1480 // Records the fact that a marking phase is no longer in progress.
1481 void set_marking_complete() {
1482 _mark_in_progress = false;
1483 }
1484 void set_marking_started() {
1485 _mark_in_progress = true;
1486 }
1487 bool mark_in_progress() {
1488 return _mark_in_progress;
1489 }
1491 // Print the maximum heap capacity.
1492 virtual size_t max_capacity() const;
1494 virtual jlong millis_since_last_gc();
1496 // Perform any cleanup actions necessary before allowing a verification.
1497 virtual void prepare_for_verify();
1499 // Perform verification.
1501 // vo == UsePrevMarking -> use "prev" marking information,
1502 // vo == UseNextMarking -> use "next" marking information
1503 // vo == UseMarkWord -> use the mark word in the object header
1504 //
1505 // NOTE: Only the "prev" marking information is guaranteed to be
1506 // consistent most of the time, so most calls to this should use
1507 // vo == UsePrevMarking.
1508 // Currently, there is only one case where this is called with
1509 // vo == UseNextMarking, which is to verify the "next" marking
1510 // information at the end of remark.
1511 // Currently there is only one place where this is called with
1512 // vo == UseMarkWord, which is to verify the marking during a
1513 // full GC.
1514 void verify(bool silent, VerifyOption vo);
1516 // Override; it uses the "prev" marking information
1517 virtual void verify(bool silent);
1518 virtual void print_on(outputStream* st) const;
1519 virtual void print_extended_on(outputStream* st) const;
1521 virtual void print_gc_threads_on(outputStream* st) const;
1522 virtual void gc_threads_do(ThreadClosure* tc) const;
1524 // Override
1525 void print_tracing_info() const;
1527 // The following two methods are helpful for debugging RSet issues.
1528 void print_cset_rsets() PRODUCT_RETURN;
1529 void print_all_rsets() PRODUCT_RETURN;
1531 // Convenience function to be used in situations where the heap type can be
1532 // asserted to be this type.
1533 static G1CollectedHeap* heap();
1535 void set_region_short_lived_locked(HeapRegion* hr);
1536 // add appropriate methods for any other surv rate groups
1538 YoungList* young_list() { return _young_list; }
1540 // debugging
1541 bool check_young_list_well_formed() {
1542 return _young_list->check_list_well_formed();
1543 }
1545 bool check_young_list_empty(bool check_heap,
1546 bool check_sample = true);
1548 // *** Stuff related to concurrent marking. It's not clear to me that so
1549 // many of these need to be public.
1551 // The functions below are helper functions that a subclass of
1552 // "CollectedHeap" can use in the implementation of its virtual
1553 // functions.
1554 // This performs a concurrent marking of the live objects in a
1555 // bitmap off to the side.
1556 void doConcurrentMark();
1558 bool isMarkedPrev(oop obj) const;
1559 bool isMarkedNext(oop obj) const;
1561 // vo == UsePrevMarking -> use "prev" marking information,
1562 // vo == UseNextMarking -> use "next" marking information,
1563 // vo == UseMarkWord -> use mark word from object header
1564 bool is_obj_dead_cond(const oop obj,
1565 const HeapRegion* hr,
1566 const VerifyOption vo) const {
1568 switch (vo) {
1569 case VerifyOption_G1UsePrevMarking:
1570 return is_obj_dead(obj, hr);
1571 case VerifyOption_G1UseNextMarking:
1572 return is_obj_ill(obj, hr);
1573 default:
1574 assert(vo == VerifyOption_G1UseMarkWord, "must be");
1575 return !obj->is_gc_marked();
1576 }
1577 }
1579 // Determine if an object is dead, given the object and also
1580 // the region to which the object belongs. An object is dead
1581 // iff a) it was not allocated since the last mark and b) it
1582 // is not marked.
1584 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1585 return
1586 !hr->obj_allocated_since_prev_marking(obj) &&
1587 !isMarkedPrev(obj);
1588 }
1590 // This is used when copying an object to survivor space.
1591 // If the object is marked live, then we mark the copy live.
1592 // If the object is allocated since the start of this mark
1593 // cycle, then we mark the copy live.
1594 // If the object has been around since the previous mark
1595 // phase, and hasn't been marked yet during this phase,
1596 // then we don't mark it, we just wait for the
1597 // current marking cycle to get to it.
1599 // This function returns true when an object has been
1600 // around since the previous marking and hasn't yet
1601 // been marked during this marking.
1603 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1604 return
1605 !hr->obj_allocated_since_next_marking(obj) &&
1606 !isMarkedNext(obj);
1607 }
1609 // Determine if an object is dead, given only the object itself.
1610 // This will find the region to which the object belongs and
1611 // then call the region version of the same function.
1613 // Added if it is in permanent gen it isn't dead.
1614 // Added if it is NULL it isn't dead.
1616 // vo == UsePrevMarking -> use "prev" marking information,
1617 // vo == UseNextMarking -> use "next" marking information,
1618 // vo == UseMarkWord -> use mark word from object header
1619 bool is_obj_dead_cond(const oop obj,
1620 const VerifyOption vo) const {
1622 switch (vo) {
1623 case VerifyOption_G1UsePrevMarking:
1624 return is_obj_dead(obj);
1625 case VerifyOption_G1UseNextMarking:
1626 return is_obj_ill(obj);
1627 default:
1628 assert(vo == VerifyOption_G1UseMarkWord, "must be");
1629 return !obj->is_gc_marked();
1630 }
1631 }
1633 bool is_obj_dead(const oop obj) const {
1634 const HeapRegion* hr = heap_region_containing(obj);
1635 if (hr == NULL) {
1636 if (Universe::heap()->is_in_permanent(obj))
1637 return false;
1638 else if (obj == NULL) return false;
1639 else return true;
1640 }
1641 else return is_obj_dead(obj, hr);
1642 }
1644 bool is_obj_ill(const oop obj) const {
1645 const HeapRegion* hr = heap_region_containing(obj);
1646 if (hr == NULL) {
1647 if (Universe::heap()->is_in_permanent(obj))
1648 return false;
1649 else if (obj == NULL) return false;
1650 else return true;
1651 }
1652 else return is_obj_ill(obj, hr);
1653 }
1655 // The following is just to alert the verification code
1656 // that a full collection has occurred and that the
1657 // remembered sets are no longer up to date.
1658 bool _full_collection;
1659 void set_full_collection() { _full_collection = true;}
1660 void clear_full_collection() {_full_collection = false;}
1661 bool full_collection() {return _full_collection;}
1663 ConcurrentMark* concurrent_mark() const { return _cm; }
1664 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1666 // The dirty cards region list is used to record a subset of regions
1667 // whose cards need clearing. The list if populated during the
1668 // remembered set scanning and drained during the card table
1669 // cleanup. Although the methods are reentrant, population/draining
1670 // phases must not overlap. For synchronization purposes the last
1671 // element on the list points to itself.
1672 HeapRegion* _dirty_cards_region_list;
1673 void push_dirty_cards_region(HeapRegion* hr);
1674 HeapRegion* pop_dirty_cards_region();
1676 public:
1677 void stop_conc_gc_threads();
1679 size_t pending_card_num();
1680 size_t max_pending_card_num();
1681 size_t cards_scanned();
1683 protected:
1684 size_t _max_heap_capacity;
1685 };
1687 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
1688 private:
1689 bool _retired;
1691 public:
1692 G1ParGCAllocBuffer(size_t gclab_word_size);
1694 void set_buf(HeapWord* buf) {
1695 ParGCAllocBuffer::set_buf(buf);
1696 _retired = false;
1697 }
1699 void retire(bool end_of_gc, bool retain) {
1700 if (_retired)
1701 return;
1702 ParGCAllocBuffer::retire(end_of_gc, retain);
1703 _retired = true;
1704 }
1705 };
1707 class G1ParScanThreadState : public StackObj {
1708 protected:
1709 G1CollectedHeap* _g1h;
1710 RefToScanQueue* _refs;
1711 DirtyCardQueue _dcq;
1712 CardTableModRefBS* _ct_bs;
1713 G1RemSet* _g1_rem;
1715 G1ParGCAllocBuffer _surviving_alloc_buffer;
1716 G1ParGCAllocBuffer _tenured_alloc_buffer;
1717 G1ParGCAllocBuffer* _alloc_buffers[GCAllocPurposeCount];
1718 ageTable _age_table;
1720 size_t _alloc_buffer_waste;
1721 size_t _undo_waste;
1723 OopsInHeapRegionClosure* _evac_failure_cl;
1724 G1ParScanHeapEvacClosure* _evac_cl;
1725 G1ParScanPartialArrayClosure* _partial_scan_cl;
1727 int _hash_seed;
1728 uint _queue_num;
1730 size_t _term_attempts;
1732 double _start;
1733 double _start_strong_roots;
1734 double _strong_roots_time;
1735 double _start_term;
1736 double _term_time;
1738 // Map from young-age-index (0 == not young, 1 is youngest) to
1739 // surviving words. base is what we get back from the malloc call
1740 size_t* _surviving_young_words_base;
1741 // this points into the array, as we use the first few entries for padding
1742 size_t* _surviving_young_words;
1744 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t))
1746 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
1748 void add_to_undo_waste(size_t waste) { _undo_waste += waste; }
1750 DirtyCardQueue& dirty_card_queue() { return _dcq; }
1751 CardTableModRefBS* ctbs() { return _ct_bs; }
1753 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) {
1754 if (!from->is_survivor()) {
1755 _g1_rem->par_write_ref(from, p, tid);
1756 }
1757 }
1759 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) {
1760 // If the new value of the field points to the same region or
1761 // is the to-space, we don't need to include it in the Rset updates.
1762 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) {
1763 size_t card_index = ctbs()->index_for(p);
1764 // If the card hasn't been added to the buffer, do it.
1765 if (ctbs()->mark_card_deferred(card_index)) {
1766 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
1767 }
1768 }
1769 }
1771 public:
1772 G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num);
1774 ~G1ParScanThreadState() {
1775 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base, mtGC);
1776 }
1778 RefToScanQueue* refs() { return _refs; }
1779 ageTable* age_table() { return &_age_table; }
1781 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) {
1782 return _alloc_buffers[purpose];
1783 }
1785 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; }
1786 size_t undo_waste() const { return _undo_waste; }
1788 #ifdef ASSERT
1789 bool verify_ref(narrowOop* ref) const;
1790 bool verify_ref(oop* ref) const;
1791 bool verify_task(StarTask ref) const;
1792 #endif // ASSERT
1794 template <class T> void push_on_queue(T* ref) {
1795 assert(verify_ref(ref), "sanity");
1796 refs()->push(ref);
1797 }
1799 template <class T> void update_rs(HeapRegion* from, T* p, int tid) {
1800 if (G1DeferredRSUpdate) {
1801 deferred_rs_update(from, p, tid);
1802 } else {
1803 immediate_rs_update(from, p, tid);
1804 }
1805 }
1807 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
1809 HeapWord* obj = NULL;
1810 size_t gclab_word_size = _g1h->desired_plab_sz(purpose);
1811 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {
1812 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);
1813 assert(gclab_word_size == alloc_buf->word_sz(),
1814 "dynamic resizing is not supported");
1815 add_to_alloc_buffer_waste(alloc_buf->words_remaining());
1816 alloc_buf->retire(false, false);
1818 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size);
1819 if (buf == NULL) return NULL; // Let caller handle allocation failure.
1820 // Otherwise.
1821 alloc_buf->set_buf(buf);
1823 obj = alloc_buf->allocate(word_sz);
1824 assert(obj != NULL, "buffer was definitely big enough...");
1825 } else {
1826 obj = _g1h->par_allocate_during_gc(purpose, word_sz);
1827 }
1828 return obj;
1829 }
1831 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {
1832 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
1833 if (obj != NULL) return obj;
1834 return allocate_slow(purpose, word_sz);
1835 }
1837 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {
1838 if (alloc_buffer(purpose)->contains(obj)) {
1839 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1),
1840 "should contain whole object");
1841 alloc_buffer(purpose)->undo_allocation(obj, word_sz);
1842 } else {
1843 CollectedHeap::fill_with_object(obj, word_sz);
1844 add_to_undo_waste(word_sz);
1845 }
1846 }
1848 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {
1849 _evac_failure_cl = evac_failure_cl;
1850 }
1851 OopsInHeapRegionClosure* evac_failure_closure() {
1852 return _evac_failure_cl;
1853 }
1855 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) {
1856 _evac_cl = evac_cl;
1857 }
1859 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) {
1860 _partial_scan_cl = partial_scan_cl;
1861 }
1863 int* hash_seed() { return &_hash_seed; }
1864 uint queue_num() { return _queue_num; }
1866 size_t term_attempts() const { return _term_attempts; }
1867 void note_term_attempt() { _term_attempts++; }
1869 void start_strong_roots() {
1870 _start_strong_roots = os::elapsedTime();
1871 }
1872 void end_strong_roots() {
1873 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
1874 }
1875 double strong_roots_time() const { return _strong_roots_time; }
1877 void start_term_time() {
1878 note_term_attempt();
1879 _start_term = os::elapsedTime();
1880 }
1881 void end_term_time() {
1882 _term_time += (os::elapsedTime() - _start_term);
1883 }
1884 double term_time() const { return _term_time; }
1886 double elapsed_time() const {
1887 return os::elapsedTime() - _start;
1888 }
1890 static void
1891 print_termination_stats_hdr(outputStream* const st = gclog_or_tty);
1892 void
1893 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const;
1895 size_t* surviving_young_words() {
1896 // We add on to hide entry 0 which accumulates surviving words for
1897 // age -1 regions (i.e. non-young ones)
1898 return _surviving_young_words;
1899 }
1901 void retire_alloc_buffers() {
1902 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
1903 size_t waste = _alloc_buffers[ap]->words_remaining();
1904 add_to_alloc_buffer_waste(waste);
1905 _alloc_buffers[ap]->retire(true, false);
1906 }
1907 }
1909 template <class T> void deal_with_reference(T* ref_to_scan) {
1910 if (has_partial_array_mask(ref_to_scan)) {
1911 _partial_scan_cl->do_oop_nv(ref_to_scan);
1912 } else {
1913 // Note: we can use "raw" versions of "region_containing" because
1914 // "obj_to_scan" is definitely in the heap, and is not in a
1915 // humongous region.
1916 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
1917 _evac_cl->set_region(r);
1918 _evac_cl->do_oop_nv(ref_to_scan);
1919 }
1920 }
1922 void deal_with_reference(StarTask ref) {
1923 assert(verify_task(ref), "sanity");
1924 if (ref.is_narrow()) {
1925 deal_with_reference((narrowOop*)ref);
1926 } else {
1927 deal_with_reference((oop*)ref);
1928 }
1929 }
1931 public:
1932 void trim_queue();
1933 };
1935 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP