Thu, 13 Feb 2014 17:44:39 +0100
8034761: Remove the do_code_roots parameter from process_strong_roots
Reviewed-by: tschatzl, mgerdin, jmasa
1 /*
2 * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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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).
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25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP
28 #include "gc_implementation/g1/concurrentMark.hpp"
29 #include "gc_implementation/g1/evacuationInfo.hpp"
30 #include "gc_implementation/g1/g1AllocRegion.hpp"
31 #include "gc_implementation/g1/g1BiasedArray.hpp"
32 #include "gc_implementation/g1/g1HRPrinter.hpp"
33 #include "gc_implementation/g1/g1MonitoringSupport.hpp"
34 #include "gc_implementation/g1/g1SATBCardTableModRefBS.hpp"
35 #include "gc_implementation/g1/g1YCTypes.hpp"
36 #include "gc_implementation/g1/heapRegionSeq.hpp"
37 #include "gc_implementation/g1/heapRegionSet.hpp"
38 #include "gc_implementation/shared/hSpaceCounters.hpp"
39 #include "gc_implementation/shared/parGCAllocBuffer.hpp"
40 #include "memory/barrierSet.hpp"
41 #include "memory/memRegion.hpp"
42 #include "memory/sharedHeap.hpp"
43 #include "utilities/stack.hpp"
45 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
46 // It uses the "Garbage First" heap organization and algorithm, which
47 // may combine concurrent marking with parallel, incremental compaction of
48 // heap subsets that will yield large amounts of garbage.
50 // Forward declarations
51 class HeapRegion;
52 class HRRSCleanupTask;
53 class GenerationSpec;
54 class OopsInHeapRegionClosure;
55 class G1KlassScanClosure;
56 class G1ScanHeapEvacClosure;
57 class ObjectClosure;
58 class SpaceClosure;
59 class CompactibleSpaceClosure;
60 class Space;
61 class G1CollectorPolicy;
62 class GenRemSet;
63 class G1RemSet;
64 class HeapRegionRemSetIterator;
65 class ConcurrentMark;
66 class ConcurrentMarkThread;
67 class ConcurrentG1Refine;
68 class ConcurrentGCTimer;
69 class GenerationCounters;
70 class STWGCTimer;
71 class G1NewTracer;
72 class G1OldTracer;
73 class EvacuationFailedInfo;
74 class nmethod;
75 class Ticks;
77 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue;
78 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
80 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
81 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
83 enum GCAllocPurpose {
84 GCAllocForTenured,
85 GCAllocForSurvived,
86 GCAllocPurposeCount
87 };
89 class YoungList : public CHeapObj<mtGC> {
90 private:
91 G1CollectedHeap* _g1h;
93 HeapRegion* _head;
95 HeapRegion* _survivor_head;
96 HeapRegion* _survivor_tail;
98 HeapRegion* _curr;
100 uint _length;
101 uint _survivor_length;
103 size_t _last_sampled_rs_lengths;
104 size_t _sampled_rs_lengths;
106 void empty_list(HeapRegion* list);
108 public:
109 YoungList(G1CollectedHeap* g1h);
111 void push_region(HeapRegion* hr);
112 void add_survivor_region(HeapRegion* hr);
114 void empty_list();
115 bool is_empty() { return _length == 0; }
116 uint length() { return _length; }
117 uint survivor_length() { return _survivor_length; }
119 // Currently we do not keep track of the used byte sum for the
120 // young list and the survivors and it'd be quite a lot of work to
121 // do so. When we'll eventually replace the young list with
122 // instances of HeapRegionLinkedList we'll get that for free. So,
123 // we'll report the more accurate information then.
124 size_t eden_used_bytes() {
125 assert(length() >= survivor_length(), "invariant");
126 return (size_t) (length() - survivor_length()) * HeapRegion::GrainBytes;
127 }
128 size_t survivor_used_bytes() {
129 return (size_t) survivor_length() * HeapRegion::GrainBytes;
130 }
132 void rs_length_sampling_init();
133 bool rs_length_sampling_more();
134 void rs_length_sampling_next();
136 void reset_sampled_info() {
137 _last_sampled_rs_lengths = 0;
138 }
139 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }
141 // for development purposes
142 void reset_auxilary_lists();
143 void clear() { _head = NULL; _length = 0; }
145 void clear_survivors() {
146 _survivor_head = NULL;
147 _survivor_tail = NULL;
148 _survivor_length = 0;
149 }
151 HeapRegion* first_region() { return _head; }
152 HeapRegion* first_survivor_region() { return _survivor_head; }
153 HeapRegion* last_survivor_region() { return _survivor_tail; }
155 // debugging
156 bool check_list_well_formed();
157 bool check_list_empty(bool check_sample = true);
158 void print();
159 };
161 class MutatorAllocRegion : public G1AllocRegion {
162 protected:
163 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
164 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
165 public:
166 MutatorAllocRegion()
167 : G1AllocRegion("Mutator Alloc Region", false /* bot_updates */) { }
168 };
170 class SurvivorGCAllocRegion : public G1AllocRegion {
171 protected:
172 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
173 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
174 public:
175 SurvivorGCAllocRegion()
176 : G1AllocRegion("Survivor GC Alloc Region", false /* bot_updates */) { }
177 };
179 class OldGCAllocRegion : public G1AllocRegion {
180 protected:
181 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
182 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
183 public:
184 OldGCAllocRegion()
185 : G1AllocRegion("Old GC Alloc Region", true /* bot_updates */) { }
186 };
188 // The G1 STW is alive closure.
189 // An instance is embedded into the G1CH and used as the
190 // (optional) _is_alive_non_header closure in the STW
191 // reference processor. It is also extensively used during
192 // reference processing during STW evacuation pauses.
193 class G1STWIsAliveClosure: public BoolObjectClosure {
194 G1CollectedHeap* _g1;
195 public:
196 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
197 bool do_object_b(oop p);
198 };
200 // Instances of this class are used for quick tests on whether a reference points
201 // into the collection set. Each of the array's elements denotes whether the
202 // corresponding region is in the collection set.
203 class G1FastCSetBiasedMappedArray : public G1BiasedMappedArray<bool> {
204 protected:
205 bool default_value() const { return false; }
206 public:
207 void clear() { G1BiasedMappedArray<bool>::clear(); }
208 };
210 class RefineCardTableEntryClosure;
212 class G1CollectedHeap : public SharedHeap {
213 friend class VM_G1CollectForAllocation;
214 friend class VM_G1CollectFull;
215 friend class VM_G1IncCollectionPause;
216 friend class VMStructs;
217 friend class MutatorAllocRegion;
218 friend class SurvivorGCAllocRegion;
219 friend class OldGCAllocRegion;
221 // Closures used in implementation.
222 template <G1Barrier barrier, bool do_mark_object>
223 friend class G1ParCopyClosure;
224 friend class G1IsAliveClosure;
225 friend class G1EvacuateFollowersClosure;
226 friend class G1ParScanThreadState;
227 friend class G1ParScanClosureSuper;
228 friend class G1ParEvacuateFollowersClosure;
229 friend class G1ParTask;
230 friend class G1FreeGarbageRegionClosure;
231 friend class RefineCardTableEntryClosure;
232 friend class G1PrepareCompactClosure;
233 friend class RegionSorter;
234 friend class RegionResetter;
235 friend class CountRCClosure;
236 friend class EvacPopObjClosure;
237 friend class G1ParCleanupCTTask;
239 // Other related classes.
240 friend class G1MarkSweep;
242 private:
243 // The one and only G1CollectedHeap, so static functions can find it.
244 static G1CollectedHeap* _g1h;
246 static size_t _humongous_object_threshold_in_words;
248 // Storage for the G1 heap.
249 VirtualSpace _g1_storage;
250 MemRegion _g1_reserved;
252 // The part of _g1_storage that is currently committed.
253 MemRegion _g1_committed;
255 // The master free list. It will satisfy all new region allocations.
256 FreeRegionList _free_list;
258 // The secondary free list which contains regions that have been
259 // freed up during the cleanup process. This will be appended to the
260 // master free list when appropriate.
261 FreeRegionList _secondary_free_list;
263 // It keeps track of the old regions.
264 HeapRegionSet _old_set;
266 // It keeps track of the humongous regions.
267 HeapRegionSet _humongous_set;
269 // The number of regions we could create by expansion.
270 uint _expansion_regions;
272 // The block offset table for the G1 heap.
273 G1BlockOffsetSharedArray* _bot_shared;
275 // Tears down the region sets / lists so that they are empty and the
276 // regions on the heap do not belong to a region set / list. The
277 // only exception is the humongous set which we leave unaltered. If
278 // free_list_only is true, it will only tear down the master free
279 // list. It is called before a Full GC (free_list_only == false) or
280 // before heap shrinking (free_list_only == true).
281 void tear_down_region_sets(bool free_list_only);
283 // Rebuilds the region sets / lists so that they are repopulated to
284 // reflect the contents of the heap. The only exception is the
285 // humongous set which was not torn down in the first place. If
286 // free_list_only is true, it will only rebuild the master free
287 // list. It is called after a Full GC (free_list_only == false) or
288 // after heap shrinking (free_list_only == true).
289 void rebuild_region_sets(bool free_list_only);
291 // The sequence of all heap regions in the heap.
292 HeapRegionSeq _hrs;
294 // Alloc region used to satisfy mutator allocation requests.
295 MutatorAllocRegion _mutator_alloc_region;
297 // Alloc region used to satisfy allocation requests by the GC for
298 // survivor objects.
299 SurvivorGCAllocRegion _survivor_gc_alloc_region;
301 // PLAB sizing policy for survivors.
302 PLABStats _survivor_plab_stats;
304 // Alloc region used to satisfy allocation requests by the GC for
305 // old objects.
306 OldGCAllocRegion _old_gc_alloc_region;
308 // PLAB sizing policy for tenured objects.
309 PLABStats _old_plab_stats;
311 PLABStats* stats_for_purpose(GCAllocPurpose purpose) {
312 PLABStats* stats = NULL;
314 switch (purpose) {
315 case GCAllocForSurvived:
316 stats = &_survivor_plab_stats;
317 break;
318 case GCAllocForTenured:
319 stats = &_old_plab_stats;
320 break;
321 default:
322 assert(false, "unrecognized GCAllocPurpose");
323 }
325 return stats;
326 }
328 // The last old region we allocated to during the last GC.
329 // Typically, it is not full so we should re-use it during the next GC.
330 HeapRegion* _retained_old_gc_alloc_region;
332 // It specifies whether we should attempt to expand the heap after a
333 // region allocation failure. If heap expansion fails we set this to
334 // false so that we don't re-attempt the heap expansion (it's likely
335 // that subsequent expansion attempts will also fail if one fails).
336 // Currently, it is only consulted during GC and it's reset at the
337 // start of each GC.
338 bool _expand_heap_after_alloc_failure;
340 // It resets the mutator alloc region before new allocations can take place.
341 void init_mutator_alloc_region();
343 // It releases the mutator alloc region.
344 void release_mutator_alloc_region();
346 // It initializes the GC alloc regions at the start of a GC.
347 void init_gc_alloc_regions(EvacuationInfo& evacuation_info);
349 // It releases the GC alloc regions at the end of a GC.
350 void release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info);
352 // It does any cleanup that needs to be done on the GC alloc regions
353 // before a Full GC.
354 void abandon_gc_alloc_regions();
356 // Helper for monitoring and management support.
357 G1MonitoringSupport* _g1mm;
359 // Determines PLAB size for a particular allocation purpose.
360 size_t desired_plab_sz(GCAllocPurpose purpose);
362 // Outside of GC pauses, the number of bytes used in all regions other
363 // than the current allocation region.
364 size_t _summary_bytes_used;
366 // This array is used for a quick test on whether a reference points into
367 // the collection set or not. Each of the array's elements denotes whether the
368 // corresponding region is in the collection set or not.
369 G1FastCSetBiasedMappedArray _in_cset_fast_test;
371 volatile unsigned _gc_time_stamp;
373 size_t* _surviving_young_words;
375 G1HRPrinter _hr_printer;
377 void setup_surviving_young_words();
378 void update_surviving_young_words(size_t* surv_young_words);
379 void cleanup_surviving_young_words();
381 // It decides whether an explicit GC should start a concurrent cycle
382 // instead of doing a STW GC. Currently, a concurrent cycle is
383 // explicitly started if:
384 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
385 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
386 // (c) cause == _g1_humongous_allocation
387 bool should_do_concurrent_full_gc(GCCause::Cause cause);
389 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
390 // concurrent cycles) we have started.
391 volatile unsigned int _old_marking_cycles_started;
393 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
394 // concurrent cycles) we have completed.
395 volatile unsigned int _old_marking_cycles_completed;
397 bool _concurrent_cycle_started;
399 // This is a non-product method that is helpful for testing. It is
400 // called at the end of a GC and artificially expands the heap by
401 // allocating a number of dead regions. This way we can induce very
402 // frequent marking cycles and stress the cleanup / concurrent
403 // cleanup code more (as all the regions that will be allocated by
404 // this method will be found dead by the marking cycle).
405 void allocate_dummy_regions() PRODUCT_RETURN;
407 // Clear RSets after a compaction. It also resets the GC time stamps.
408 void clear_rsets_post_compaction();
410 // If the HR printer is active, dump the state of the regions in the
411 // heap after a compaction.
412 void print_hrs_post_compaction();
414 double verify(bool guard, const char* msg);
415 void verify_before_gc();
416 void verify_after_gc();
418 void log_gc_header();
419 void log_gc_footer(double pause_time_sec);
421 // These are macros so that, if the assert fires, we get the correct
422 // line number, file, etc.
424 #define heap_locking_asserts_err_msg(_extra_message_) \
425 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
426 (_extra_message_), \
427 BOOL_TO_STR(Heap_lock->owned_by_self()), \
428 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
429 BOOL_TO_STR(Thread::current()->is_VM_thread()))
431 #define assert_heap_locked() \
432 do { \
433 assert(Heap_lock->owned_by_self(), \
434 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
435 } while (0)
437 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
438 do { \
439 assert(Heap_lock->owned_by_self() || \
440 (SafepointSynchronize::is_at_safepoint() && \
441 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
442 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
443 "should be at a safepoint")); \
444 } while (0)
446 #define assert_heap_locked_and_not_at_safepoint() \
447 do { \
448 assert(Heap_lock->owned_by_self() && \
449 !SafepointSynchronize::is_at_safepoint(), \
450 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
451 "should not be at a safepoint")); \
452 } while (0)
454 #define assert_heap_not_locked() \
455 do { \
456 assert(!Heap_lock->owned_by_self(), \
457 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
458 } while (0)
460 #define assert_heap_not_locked_and_not_at_safepoint() \
461 do { \
462 assert(!Heap_lock->owned_by_self() && \
463 !SafepointSynchronize::is_at_safepoint(), \
464 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
465 "should not be at a safepoint")); \
466 } while (0)
468 #define assert_at_safepoint(_should_be_vm_thread_) \
469 do { \
470 assert(SafepointSynchronize::is_at_safepoint() && \
471 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
472 heap_locking_asserts_err_msg("should be at a safepoint")); \
473 } while (0)
475 #define assert_not_at_safepoint() \
476 do { \
477 assert(!SafepointSynchronize::is_at_safepoint(), \
478 heap_locking_asserts_err_msg("should not be at a safepoint")); \
479 } while (0)
481 protected:
483 // The young region list.
484 YoungList* _young_list;
486 // The current policy object for the collector.
487 G1CollectorPolicy* _g1_policy;
489 // This is the second level of trying to allocate a new region. If
490 // new_region() didn't find a region on the free_list, this call will
491 // check whether there's anything available on the
492 // secondary_free_list and/or wait for more regions to appear on
493 // that list, if _free_regions_coming is set.
494 HeapRegion* new_region_try_secondary_free_list(bool is_old);
496 // Try to allocate a single non-humongous HeapRegion sufficient for
497 // an allocation of the given word_size. If do_expand is true,
498 // attempt to expand the heap if necessary to satisfy the allocation
499 // request. If the region is to be used as an old region or for a
500 // humongous object, set is_old to true. If not, to false.
501 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand);
503 // Attempt to satisfy a humongous allocation request of the given
504 // size by finding a contiguous set of free regions of num_regions
505 // length and remove them from the master free list. Return the
506 // index of the first region or G1_NULL_HRS_INDEX if the search
507 // was unsuccessful.
508 uint humongous_obj_allocate_find_first(uint num_regions,
509 size_t word_size);
511 // Initialize a contiguous set of free regions of length num_regions
512 // and starting at index first so that they appear as a single
513 // humongous region.
514 HeapWord* humongous_obj_allocate_initialize_regions(uint first,
515 uint num_regions,
516 size_t word_size);
518 // Attempt to allocate a humongous object of the given size. Return
519 // NULL if unsuccessful.
520 HeapWord* humongous_obj_allocate(size_t word_size);
522 // The following two methods, allocate_new_tlab() and
523 // mem_allocate(), are the two main entry points from the runtime
524 // into the G1's allocation routines. They have the following
525 // assumptions:
526 //
527 // * They should both be called outside safepoints.
528 //
529 // * They should both be called without holding the Heap_lock.
530 //
531 // * All allocation requests for new TLABs should go to
532 // allocate_new_tlab().
533 //
534 // * All non-TLAB allocation requests should go to mem_allocate().
535 //
536 // * If either call cannot satisfy the allocation request using the
537 // current allocating region, they will try to get a new one. If
538 // this fails, they will attempt to do an evacuation pause and
539 // retry the allocation.
540 //
541 // * If all allocation attempts fail, even after trying to schedule
542 // an evacuation pause, allocate_new_tlab() will return NULL,
543 // whereas mem_allocate() will attempt a heap expansion and/or
544 // schedule a Full GC.
545 //
546 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
547 // should never be called with word_size being humongous. All
548 // humongous allocation requests should go to mem_allocate() which
549 // will satisfy them with a special path.
551 virtual HeapWord* allocate_new_tlab(size_t word_size);
553 virtual HeapWord* mem_allocate(size_t word_size,
554 bool* gc_overhead_limit_was_exceeded);
556 // The following three methods take a gc_count_before_ret
557 // parameter which is used to return the GC count if the method
558 // returns NULL. Given that we are required to read the GC count
559 // while holding the Heap_lock, and these paths will take the
560 // Heap_lock at some point, it's easier to get them to read the GC
561 // count while holding the Heap_lock before they return NULL instead
562 // of the caller (namely: mem_allocate()) having to also take the
563 // Heap_lock just to read the GC count.
565 // First-level mutator allocation attempt: try to allocate out of
566 // the mutator alloc region without taking the Heap_lock. This
567 // should only be used for non-humongous allocations.
568 inline HeapWord* attempt_allocation(size_t word_size,
569 unsigned int* gc_count_before_ret,
570 int* gclocker_retry_count_ret);
572 // Second-level mutator allocation attempt: take the Heap_lock and
573 // retry the allocation attempt, potentially scheduling a GC
574 // pause. This should only be used for non-humongous allocations.
575 HeapWord* attempt_allocation_slow(size_t word_size,
576 unsigned int* gc_count_before_ret,
577 int* gclocker_retry_count_ret);
579 // Takes the Heap_lock and attempts a humongous allocation. It can
580 // potentially schedule a GC pause.
581 HeapWord* attempt_allocation_humongous(size_t word_size,
582 unsigned int* gc_count_before_ret,
583 int* gclocker_retry_count_ret);
585 // Allocation attempt that should be called during safepoints (e.g.,
586 // at the end of a successful GC). expect_null_mutator_alloc_region
587 // specifies whether the mutator alloc region is expected to be NULL
588 // or not.
589 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
590 bool expect_null_mutator_alloc_region);
592 // It dirties the cards that cover the block so that so that the post
593 // write barrier never queues anything when updating objects on this
594 // block. It is assumed (and in fact we assert) that the block
595 // belongs to a young region.
596 inline void dirty_young_block(HeapWord* start, size_t word_size);
598 // Allocate blocks during garbage collection. Will ensure an
599 // allocation region, either by picking one or expanding the
600 // heap, and then allocate a block of the given size. The block
601 // may not be a humongous - it must fit into a single heap region.
602 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size);
604 HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose,
605 HeapRegion* alloc_region,
606 bool par,
607 size_t word_size);
609 // Ensure that no further allocations can happen in "r", bearing in mind
610 // that parallel threads might be attempting allocations.
611 void par_allocate_remaining_space(HeapRegion* r);
613 // Allocation attempt during GC for a survivor object / PLAB.
614 inline HeapWord* survivor_attempt_allocation(size_t word_size);
616 // Allocation attempt during GC for an old object / PLAB.
617 inline HeapWord* old_attempt_allocation(size_t word_size);
619 // These methods are the "callbacks" from the G1AllocRegion class.
621 // For mutator alloc regions.
622 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
623 void retire_mutator_alloc_region(HeapRegion* alloc_region,
624 size_t allocated_bytes);
626 // For GC alloc regions.
627 HeapRegion* new_gc_alloc_region(size_t word_size, uint count,
628 GCAllocPurpose ap);
629 void retire_gc_alloc_region(HeapRegion* alloc_region,
630 size_t allocated_bytes, GCAllocPurpose ap);
632 // - if explicit_gc is true, the GC is for a System.gc() or a heap
633 // inspection request and should collect the entire heap
634 // - if clear_all_soft_refs is true, all soft references should be
635 // cleared during the GC
636 // - if explicit_gc is false, word_size describes the allocation that
637 // the GC should attempt (at least) to satisfy
638 // - it returns false if it is unable to do the collection due to the
639 // GC locker being active, true otherwise
640 bool do_collection(bool explicit_gc,
641 bool clear_all_soft_refs,
642 size_t word_size);
644 // Callback from VM_G1CollectFull operation.
645 // Perform a full collection.
646 virtual void do_full_collection(bool clear_all_soft_refs);
648 // Resize the heap if necessary after a full collection. If this is
649 // after a collect-for allocation, "word_size" is the allocation size,
650 // and will be considered part of the used portion of the heap.
651 void resize_if_necessary_after_full_collection(size_t word_size);
653 // Callback from VM_G1CollectForAllocation operation.
654 // This function does everything necessary/possible to satisfy a
655 // failed allocation request (including collection, expansion, etc.)
656 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded);
658 // Attempting to expand the heap sufficiently
659 // to support an allocation of the given "word_size". If
660 // successful, perform the allocation and return the address of the
661 // allocated block, or else "NULL".
662 HeapWord* expand_and_allocate(size_t word_size);
664 // Process any reference objects discovered during
665 // an incremental evacuation pause.
666 void process_discovered_references(uint no_of_gc_workers);
668 // Enqueue any remaining discovered references
669 // after processing.
670 void enqueue_discovered_references(uint no_of_gc_workers);
672 public:
674 G1MonitoringSupport* g1mm() {
675 assert(_g1mm != NULL, "should have been initialized");
676 return _g1mm;
677 }
679 // Expand the garbage-first heap by at least the given size (in bytes!).
680 // Returns true if the heap was expanded by the requested amount;
681 // false otherwise.
682 // (Rounds up to a HeapRegion boundary.)
683 bool expand(size_t expand_bytes);
685 // Do anything common to GC's.
686 virtual void gc_prologue(bool full);
687 virtual void gc_epilogue(bool full);
689 // We register a region with the fast "in collection set" test. We
690 // simply set to true the array slot corresponding to this region.
691 void register_region_with_in_cset_fast_test(HeapRegion* r) {
692 _in_cset_fast_test.set_by_index(r->hrs_index(), true);
693 }
695 // This is a fast test on whether a reference points into the
696 // collection set or not. Assume that the reference
697 // points into the heap.
698 inline bool in_cset_fast_test(oop obj);
700 void clear_cset_fast_test() {
701 _in_cset_fast_test.clear();
702 }
704 // This is called at the start of either a concurrent cycle or a Full
705 // GC to update the number of old marking cycles started.
706 void increment_old_marking_cycles_started();
708 // This is called at the end of either a concurrent cycle or a Full
709 // GC to update the number of old marking cycles completed. Those two
710 // can happen in a nested fashion, i.e., we start a concurrent
711 // cycle, a Full GC happens half-way through it which ends first,
712 // and then the cycle notices that a Full GC happened and ends
713 // too. The concurrent parameter is a boolean to help us do a bit
714 // tighter consistency checking in the method. If concurrent is
715 // false, the caller is the inner caller in the nesting (i.e., the
716 // Full GC). If concurrent is true, the caller is the outer caller
717 // in this nesting (i.e., the concurrent cycle). Further nesting is
718 // not currently supported. The end of this call also notifies
719 // the FullGCCount_lock in case a Java thread is waiting for a full
720 // GC to happen (e.g., it called System.gc() with
721 // +ExplicitGCInvokesConcurrent).
722 void increment_old_marking_cycles_completed(bool concurrent);
724 unsigned int old_marking_cycles_completed() {
725 return _old_marking_cycles_completed;
726 }
728 void register_concurrent_cycle_start(const Ticks& start_time);
729 void register_concurrent_cycle_end();
730 void trace_heap_after_concurrent_cycle();
732 G1YCType yc_type();
734 G1HRPrinter* hr_printer() { return &_hr_printer; }
736 // Frees a non-humongous region by initializing its contents and
737 // adding it to the free list that's passed as a parameter (this is
738 // usually a local list which will be appended to the master free
739 // list later). The used bytes of freed regions are accumulated in
740 // pre_used. If par is true, the region's RSet will not be freed
741 // up. The assumption is that this will be done later.
742 // The locked parameter indicates if the caller has already taken
743 // care of proper synchronization. This may allow some optimizations.
744 void free_region(HeapRegion* hr,
745 FreeRegionList* free_list,
746 bool par,
747 bool locked = false);
749 // Frees a humongous region by collapsing it into individual regions
750 // and calling free_region() for each of them. The freed regions
751 // will be added to the free list that's passed as a parameter (this
752 // is usually a local list which will be appended to the master free
753 // list later). The used bytes of freed regions are accumulated in
754 // pre_used. If par is true, the region's RSet will not be freed
755 // up. The assumption is that this will be done later.
756 void free_humongous_region(HeapRegion* hr,
757 FreeRegionList* free_list,
758 bool par);
759 protected:
761 // Shrink the garbage-first heap by at most the given size (in bytes!).
762 // (Rounds down to a HeapRegion boundary.)
763 virtual void shrink(size_t expand_bytes);
764 void shrink_helper(size_t expand_bytes);
766 #if TASKQUEUE_STATS
767 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
768 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
769 void reset_taskqueue_stats();
770 #endif // TASKQUEUE_STATS
772 // Schedule the VM operation that will do an evacuation pause to
773 // satisfy an allocation request of word_size. *succeeded will
774 // return whether the VM operation was successful (it did do an
775 // evacuation pause) or not (another thread beat us to it or the GC
776 // locker was active). Given that we should not be holding the
777 // Heap_lock when we enter this method, we will pass the
778 // gc_count_before (i.e., total_collections()) as a parameter since
779 // it has to be read while holding the Heap_lock. Currently, both
780 // methods that call do_collection_pause() release the Heap_lock
781 // before the call, so it's easy to read gc_count_before just before.
782 HeapWord* do_collection_pause(size_t word_size,
783 unsigned int gc_count_before,
784 bool* succeeded,
785 GCCause::Cause gc_cause);
787 // The guts of the incremental collection pause, executed by the vm
788 // thread. It returns false if it is unable to do the collection due
789 // to the GC locker being active, true otherwise
790 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
792 // Actually do the work of evacuating the collection set.
793 void evacuate_collection_set(EvacuationInfo& evacuation_info);
795 // The g1 remembered set of the heap.
796 G1RemSet* _g1_rem_set;
798 // A set of cards that cover the objects for which the Rsets should be updated
799 // concurrently after the collection.
800 DirtyCardQueueSet _dirty_card_queue_set;
802 // The closure used to refine a single card.
803 RefineCardTableEntryClosure* _refine_cte_cl;
805 // A function to check the consistency of dirty card logs.
806 void check_ct_logs_at_safepoint();
808 // A DirtyCardQueueSet that is used to hold cards that contain
809 // references into the current collection set. This is used to
810 // update the remembered sets of the regions in the collection
811 // set in the event of an evacuation failure.
812 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
814 // After a collection pause, make the regions in the CS into free
815 // regions.
816 void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info);
818 // Abandon the current collection set without recording policy
819 // statistics or updating free lists.
820 void abandon_collection_set(HeapRegion* cs_head);
822 // Applies "scan_non_heap_roots" to roots outside the heap,
823 // "scan_rs" to roots inside the heap (having done "set_region" to
824 // indicate the region in which the root resides),
825 // and does "scan_metadata" If "scan_rs" is
826 // NULL, then this step is skipped. The "worker_i"
827 // param is for use with parallel roots processing, and should be
828 // the "i" of the calling parallel worker thread's work(i) function.
829 // In the sequential case this param will be ignored.
830 void g1_process_strong_roots(bool is_scavenging,
831 ScanningOption so,
832 OopClosure* scan_non_heap_roots,
833 OopsInHeapRegionClosure* scan_rs,
834 G1KlassScanClosure* scan_klasses,
835 uint worker_i);
837 // Notifies all the necessary spaces that the committed space has
838 // been updated (either expanded or shrunk). It should be called
839 // after _g1_storage is updated.
840 void update_committed_space(HeapWord* old_end, HeapWord* new_end);
842 // The concurrent marker (and the thread it runs in.)
843 ConcurrentMark* _cm;
844 ConcurrentMarkThread* _cmThread;
845 bool _mark_in_progress;
847 // The concurrent refiner.
848 ConcurrentG1Refine* _cg1r;
850 // The parallel task queues
851 RefToScanQueueSet *_task_queues;
853 // True iff a evacuation has failed in the current collection.
854 bool _evacuation_failed;
856 EvacuationFailedInfo* _evacuation_failed_info_array;
858 // Failed evacuations cause some logical from-space objects to have
859 // forwarding pointers to themselves. Reset them.
860 void remove_self_forwarding_pointers();
862 // Together, these store an object with a preserved mark, and its mark value.
863 Stack<oop, mtGC> _objs_with_preserved_marks;
864 Stack<markOop, mtGC> _preserved_marks_of_objs;
866 // Preserve the mark of "obj", if necessary, in preparation for its mark
867 // word being overwritten with a self-forwarding-pointer.
868 void preserve_mark_if_necessary(oop obj, markOop m);
870 // The stack of evac-failure objects left to be scanned.
871 GrowableArray<oop>* _evac_failure_scan_stack;
872 // The closure to apply to evac-failure objects.
874 OopsInHeapRegionClosure* _evac_failure_closure;
875 // Set the field above.
876 void
877 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
878 _evac_failure_closure = evac_failure_closure;
879 }
881 // Push "obj" on the scan stack.
882 void push_on_evac_failure_scan_stack(oop obj);
883 // Process scan stack entries until the stack is empty.
884 void drain_evac_failure_scan_stack();
885 // True iff an invocation of "drain_scan_stack" is in progress; to
886 // prevent unnecessary recursion.
887 bool _drain_in_progress;
889 // Do any necessary initialization for evacuation-failure handling.
890 // "cl" is the closure that will be used to process evac-failure
891 // objects.
892 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
893 // Do any necessary cleanup for evacuation-failure handling data
894 // structures.
895 void finalize_for_evac_failure();
897 // An attempt to evacuate "obj" has failed; take necessary steps.
898 oop handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, oop obj);
899 void handle_evacuation_failure_common(oop obj, markOop m);
901 #ifndef PRODUCT
902 // Support for forcing evacuation failures. Analogous to
903 // PromotionFailureALot for the other collectors.
905 // Records whether G1EvacuationFailureALot should be in effect
906 // for the current GC
907 bool _evacuation_failure_alot_for_current_gc;
909 // Used to record the GC number for interval checking when
910 // determining whether G1EvaucationFailureALot is in effect
911 // for the current GC.
912 size_t _evacuation_failure_alot_gc_number;
914 // Count of the number of evacuations between failures.
915 volatile size_t _evacuation_failure_alot_count;
917 // Set whether G1EvacuationFailureALot should be in effect
918 // for the current GC (based upon the type of GC and which
919 // command line flags are set);
920 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young,
921 bool during_initial_mark,
922 bool during_marking);
924 inline void set_evacuation_failure_alot_for_current_gc();
926 // Return true if it's time to cause an evacuation failure.
927 inline bool evacuation_should_fail();
929 // Reset the G1EvacuationFailureALot counters. Should be called at
930 // the end of an evacuation pause in which an evacuation failure occurred.
931 inline void reset_evacuation_should_fail();
932 #endif // !PRODUCT
934 // ("Weak") Reference processing support.
935 //
936 // G1 has 2 instances of the reference processor class. One
937 // (_ref_processor_cm) handles reference object discovery
938 // and subsequent processing during concurrent marking cycles.
939 //
940 // The other (_ref_processor_stw) handles reference object
941 // discovery and processing during full GCs and incremental
942 // evacuation pauses.
943 //
944 // During an incremental pause, reference discovery will be
945 // temporarily disabled for _ref_processor_cm and will be
946 // enabled for _ref_processor_stw. At the end of the evacuation
947 // pause references discovered by _ref_processor_stw will be
948 // processed and discovery will be disabled. The previous
949 // setting for reference object discovery for _ref_processor_cm
950 // will be re-instated.
951 //
952 // At the start of marking:
953 // * Discovery by the CM ref processor is verified to be inactive
954 // and it's discovered lists are empty.
955 // * Discovery by the CM ref processor is then enabled.
956 //
957 // At the end of marking:
958 // * Any references on the CM ref processor's discovered
959 // lists are processed (possibly MT).
960 //
961 // At the start of full GC we:
962 // * Disable discovery by the CM ref processor and
963 // empty CM ref processor's discovered lists
964 // (without processing any entries).
965 // * Verify that the STW ref processor is inactive and it's
966 // discovered lists are empty.
967 // * Temporarily set STW ref processor discovery as single threaded.
968 // * Temporarily clear the STW ref processor's _is_alive_non_header
969 // field.
970 // * Finally enable discovery by the STW ref processor.
971 //
972 // The STW ref processor is used to record any discovered
973 // references during the full GC.
974 //
975 // At the end of a full GC we:
976 // * Enqueue any reference objects discovered by the STW ref processor
977 // that have non-live referents. This has the side-effect of
978 // making the STW ref processor inactive by disabling discovery.
979 // * Verify that the CM ref processor is still inactive
980 // and no references have been placed on it's discovered
981 // lists (also checked as a precondition during initial marking).
983 // The (stw) reference processor...
984 ReferenceProcessor* _ref_processor_stw;
986 STWGCTimer* _gc_timer_stw;
987 ConcurrentGCTimer* _gc_timer_cm;
989 G1OldTracer* _gc_tracer_cm;
990 G1NewTracer* _gc_tracer_stw;
992 // During reference object discovery, the _is_alive_non_header
993 // closure (if non-null) is applied to the referent object to
994 // determine whether the referent is live. If so then the
995 // reference object does not need to be 'discovered' and can
996 // be treated as a regular oop. This has the benefit of reducing
997 // the number of 'discovered' reference objects that need to
998 // be processed.
999 //
1000 // Instance of the is_alive closure for embedding into the
1001 // STW reference processor as the _is_alive_non_header field.
1002 // Supplying a value for the _is_alive_non_header field is
1003 // optional but doing so prevents unnecessary additions to
1004 // the discovered lists during reference discovery.
1005 G1STWIsAliveClosure _is_alive_closure_stw;
1007 // The (concurrent marking) reference processor...
1008 ReferenceProcessor* _ref_processor_cm;
1010 // Instance of the concurrent mark is_alive closure for embedding
1011 // into the Concurrent Marking reference processor as the
1012 // _is_alive_non_header field. Supplying a value for the
1013 // _is_alive_non_header field is optional but doing so prevents
1014 // unnecessary additions to the discovered lists during reference
1015 // discovery.
1016 G1CMIsAliveClosure _is_alive_closure_cm;
1018 // Cache used by G1CollectedHeap::start_cset_region_for_worker().
1019 HeapRegion** _worker_cset_start_region;
1021 // Time stamp to validate the regions recorded in the cache
1022 // used by G1CollectedHeap::start_cset_region_for_worker().
1023 // The heap region entry for a given worker is valid iff
1024 // the associated time stamp value matches the current value
1025 // of G1CollectedHeap::_gc_time_stamp.
1026 unsigned int* _worker_cset_start_region_time_stamp;
1028 enum G1H_process_strong_roots_tasks {
1029 G1H_PS_filter_satb_buffers,
1030 G1H_PS_refProcessor_oops_do,
1031 // Leave this one last.
1032 G1H_PS_NumElements
1033 };
1035 SubTasksDone* _process_strong_tasks;
1037 volatile bool _free_regions_coming;
1039 public:
1041 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
1043 void set_refine_cte_cl_concurrency(bool concurrent);
1045 RefToScanQueue *task_queue(int i) const;
1047 // A set of cards where updates happened during the GC
1048 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
1050 // A DirtyCardQueueSet that is used to hold cards that contain
1051 // references into the current collection set. This is used to
1052 // update the remembered sets of the regions in the collection
1053 // set in the event of an evacuation failure.
1054 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
1055 { return _into_cset_dirty_card_queue_set; }
1057 // Create a G1CollectedHeap with the specified policy.
1058 // Must call the initialize method afterwards.
1059 // May not return if something goes wrong.
1060 G1CollectedHeap(G1CollectorPolicy* policy);
1062 // Initialize the G1CollectedHeap to have the initial and
1063 // maximum sizes and remembered and barrier sets
1064 // specified by the policy object.
1065 jint initialize();
1067 virtual void stop();
1069 // Return the (conservative) maximum heap alignment for any G1 heap
1070 static size_t conservative_max_heap_alignment();
1072 // Initialize weak reference processing.
1073 virtual void ref_processing_init();
1075 void set_par_threads(uint t) {
1076 SharedHeap::set_par_threads(t);
1077 // Done in SharedHeap but oddly there are
1078 // two _process_strong_tasks's in a G1CollectedHeap
1079 // so do it here too.
1080 _process_strong_tasks->set_n_threads(t);
1081 }
1083 // Set _n_par_threads according to a policy TBD.
1084 void set_par_threads();
1086 void set_n_termination(int t) {
1087 _process_strong_tasks->set_n_threads(t);
1088 }
1090 virtual CollectedHeap::Name kind() const {
1091 return CollectedHeap::G1CollectedHeap;
1092 }
1094 // The current policy object for the collector.
1095 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
1097 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); }
1099 // Adaptive size policy. No such thing for g1.
1100 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
1102 // The rem set and barrier set.
1103 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
1105 unsigned get_gc_time_stamp() {
1106 return _gc_time_stamp;
1107 }
1109 inline void reset_gc_time_stamp();
1111 void check_gc_time_stamps() PRODUCT_RETURN;
1113 inline void increment_gc_time_stamp();
1115 // Reset the given region's GC timestamp. If it's starts humongous,
1116 // also reset the GC timestamp of its corresponding
1117 // continues humongous regions too.
1118 void reset_gc_time_stamps(HeapRegion* hr);
1120 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
1121 DirtyCardQueue* into_cset_dcq,
1122 bool concurrent, uint worker_i);
1124 // The shared block offset table array.
1125 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
1127 // Reference Processing accessors
1129 // The STW reference processor....
1130 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1132 // The Concurrent Marking reference processor...
1133 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1135 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; }
1136 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; }
1138 virtual size_t capacity() const;
1139 virtual size_t used() const;
1140 // This should be called when we're not holding the heap lock. The
1141 // result might be a bit inaccurate.
1142 size_t used_unlocked() const;
1143 size_t recalculate_used() const;
1145 // These virtual functions do the actual allocation.
1146 // Some heaps may offer a contiguous region for shared non-blocking
1147 // allocation, via inlined code (by exporting the address of the top and
1148 // end fields defining the extent of the contiguous allocation region.)
1149 // But G1CollectedHeap doesn't yet support this.
1151 // Return an estimate of the maximum allocation that could be performed
1152 // without triggering any collection or expansion activity. In a
1153 // generational collector, for example, this is probably the largest
1154 // allocation that could be supported (without expansion) in the youngest
1155 // generation. It is "unsafe" because no locks are taken; the result
1156 // should be treated as an approximation, not a guarantee, for use in
1157 // heuristic resizing decisions.
1158 virtual size_t unsafe_max_alloc();
1160 virtual bool is_maximal_no_gc() const {
1161 return _g1_storage.uncommitted_size() == 0;
1162 }
1164 // The total number of regions in the heap.
1165 uint n_regions() { return _hrs.length(); }
1167 // The max number of regions in the heap.
1168 uint max_regions() { return _hrs.max_length(); }
1170 // The number of regions that are completely free.
1171 uint free_regions() { return _free_list.length(); }
1173 // The number of regions that are not completely free.
1174 uint used_regions() { return n_regions() - free_regions(); }
1176 // The number of regions available for "regular" expansion.
1177 uint expansion_regions() { return _expansion_regions; }
1179 // Factory method for HeapRegion instances. It will return NULL if
1180 // the allocation fails.
1181 HeapRegion* new_heap_region(uint hrs_index, HeapWord* bottom);
1183 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1184 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1185 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
1186 void verify_dirty_young_regions() PRODUCT_RETURN;
1188 // verify_region_sets() performs verification over the region
1189 // lists. It will be compiled in the product code to be used when
1190 // necessary (i.e., during heap verification).
1191 void verify_region_sets();
1193 // verify_region_sets_optional() is planted in the code for
1194 // list verification in non-product builds (and it can be enabled in
1195 // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1).
1196 #if HEAP_REGION_SET_FORCE_VERIFY
1197 void verify_region_sets_optional() {
1198 verify_region_sets();
1199 }
1200 #else // HEAP_REGION_SET_FORCE_VERIFY
1201 void verify_region_sets_optional() { }
1202 #endif // HEAP_REGION_SET_FORCE_VERIFY
1204 #ifdef ASSERT
1205 bool is_on_master_free_list(HeapRegion* hr) {
1206 return hr->containing_set() == &_free_list;
1207 }
1208 #endif // ASSERT
1210 // Wrapper for the region list operations that can be called from
1211 // methods outside this class.
1213 void secondary_free_list_add(FreeRegionList* list) {
1214 _secondary_free_list.add_ordered(list);
1215 }
1217 void append_secondary_free_list() {
1218 _free_list.add_ordered(&_secondary_free_list);
1219 }
1221 void append_secondary_free_list_if_not_empty_with_lock() {
1222 // If the secondary free list looks empty there's no reason to
1223 // take the lock and then try to append it.
1224 if (!_secondary_free_list.is_empty()) {
1225 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1226 append_secondary_free_list();
1227 }
1228 }
1230 inline void old_set_remove(HeapRegion* hr);
1232 size_t non_young_capacity_bytes() {
1233 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes();
1234 }
1236 void set_free_regions_coming();
1237 void reset_free_regions_coming();
1238 bool free_regions_coming() { return _free_regions_coming; }
1239 void wait_while_free_regions_coming();
1241 // Determine whether the given region is one that we are using as an
1242 // old GC alloc region.
1243 bool is_old_gc_alloc_region(HeapRegion* hr) {
1244 return hr == _retained_old_gc_alloc_region;
1245 }
1247 // Perform a collection of the heap; intended for use in implementing
1248 // "System.gc". This probably implies as full a collection as the
1249 // "CollectedHeap" supports.
1250 virtual void collect(GCCause::Cause cause);
1252 // The same as above but assume that the caller holds the Heap_lock.
1253 void collect_locked(GCCause::Cause cause);
1255 // True iff an evacuation has failed in the most-recent collection.
1256 bool evacuation_failed() { return _evacuation_failed; }
1258 void remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, const HeapRegionSetCount& humongous_regions_removed);
1259 void prepend_to_freelist(FreeRegionList* list);
1260 void decrement_summary_bytes(size_t bytes);
1262 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1263 virtual bool is_in(const void* p) const;
1265 // Return "TRUE" iff the given object address is within the collection
1266 // set.
1267 inline bool obj_in_cs(oop obj);
1269 // Return "TRUE" iff the given object address is in the reserved
1270 // region of g1.
1271 bool is_in_g1_reserved(const void* p) const {
1272 return _g1_reserved.contains(p);
1273 }
1275 // Returns a MemRegion that corresponds to the space that has been
1276 // reserved for the heap
1277 MemRegion g1_reserved() {
1278 return _g1_reserved;
1279 }
1281 // Returns a MemRegion that corresponds to the space that has been
1282 // committed in the heap
1283 MemRegion g1_committed() {
1284 return _g1_committed;
1285 }
1287 virtual bool is_in_closed_subset(const void* p) const;
1289 G1SATBCardTableModRefBS* g1_barrier_set() {
1290 return (G1SATBCardTableModRefBS*) barrier_set();
1291 }
1293 // This resets the card table to all zeros. It is used after
1294 // a collection pause which used the card table to claim cards.
1295 void cleanUpCardTable();
1297 // Iteration functions.
1299 // Iterate over all the ref-containing fields of all objects, calling
1300 // "cl.do_oop" on each.
1301 virtual void oop_iterate(ExtendedOopClosure* cl);
1303 // Same as above, restricted to a memory region.
1304 void oop_iterate(MemRegion mr, ExtendedOopClosure* cl);
1306 // Iterate over all objects, calling "cl.do_object" on each.
1307 virtual void object_iterate(ObjectClosure* cl);
1309 virtual void safe_object_iterate(ObjectClosure* cl) {
1310 object_iterate(cl);
1311 }
1313 // Iterate over all spaces in use in the heap, in ascending address order.
1314 virtual void space_iterate(SpaceClosure* cl);
1316 // Iterate over heap regions, in address order, terminating the
1317 // iteration early if the "doHeapRegion" method returns "true".
1318 void heap_region_iterate(HeapRegionClosure* blk) const;
1320 // Return the region with the given index. It assumes the index is valid.
1321 inline HeapRegion* region_at(uint index) const;
1323 // Divide the heap region sequence into "chunks" of some size (the number
1324 // of regions divided by the number of parallel threads times some
1325 // overpartition factor, currently 4). Assumes that this will be called
1326 // in parallel by ParallelGCThreads worker threads with discinct worker
1327 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
1328 // calls will use the same "claim_value", and that that claim value is
1329 // different from the claim_value of any heap region before the start of
1330 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by
1331 // attempting to claim the first region in each chunk, and, if
1332 // successful, applying the closure to each region in the chunk (and
1333 // setting the claim value of the second and subsequent regions of the
1334 // chunk.) For now requires that "doHeapRegion" always returns "false",
1335 // i.e., that a closure never attempt to abort a traversal.
1336 void heap_region_par_iterate_chunked(HeapRegionClosure* blk,
1337 uint worker,
1338 uint no_of_par_workers,
1339 jint claim_value);
1341 // It resets all the region claim values to the default.
1342 void reset_heap_region_claim_values();
1344 // Resets the claim values of regions in the current
1345 // collection set to the default.
1346 void reset_cset_heap_region_claim_values();
1348 #ifdef ASSERT
1349 bool check_heap_region_claim_values(jint claim_value);
1351 // Same as the routine above but only checks regions in the
1352 // current collection set.
1353 bool check_cset_heap_region_claim_values(jint claim_value);
1354 #endif // ASSERT
1356 // Clear the cached cset start regions and (more importantly)
1357 // the time stamps. Called when we reset the GC time stamp.
1358 void clear_cset_start_regions();
1360 // Given the id of a worker, obtain or calculate a suitable
1361 // starting region for iterating over the current collection set.
1362 HeapRegion* start_cset_region_for_worker(uint worker_i);
1364 // This is a convenience method that is used by the
1365 // HeapRegionIterator classes to calculate the starting region for
1366 // each worker so that they do not all start from the same region.
1367 HeapRegion* start_region_for_worker(uint worker_i, uint no_of_par_workers);
1369 // Iterate over the regions (if any) in the current collection set.
1370 void collection_set_iterate(HeapRegionClosure* blk);
1372 // As above but starting from region r
1373 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1375 // Returns the first (lowest address) compactible space in the heap.
1376 virtual CompactibleSpace* first_compactible_space();
1378 // A CollectedHeap will contain some number of spaces. This finds the
1379 // space containing a given address, or else returns NULL.
1380 virtual Space* space_containing(const void* addr) const;
1382 // A G1CollectedHeap will contain some number of heap regions. This
1383 // finds the region containing a given address, or else returns NULL.
1384 template <class T>
1385 inline HeapRegion* heap_region_containing(const T addr) const;
1387 // Like the above, but requires "addr" to be in the heap (to avoid a
1388 // null-check), and unlike the above, may return an continuing humongous
1389 // region.
1390 template <class T>
1391 inline HeapRegion* heap_region_containing_raw(const T addr) const;
1393 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1394 // each address in the (reserved) heap is a member of exactly
1395 // one block. The defining characteristic of a block is that it is
1396 // possible to find its size, and thus to progress forward to the next
1397 // block. (Blocks may be of different sizes.) Thus, blocks may
1398 // represent Java objects, or they might be free blocks in a
1399 // free-list-based heap (or subheap), as long as the two kinds are
1400 // distinguishable and the size of each is determinable.
1402 // Returns the address of the start of the "block" that contains the
1403 // address "addr". We say "blocks" instead of "object" since some heaps
1404 // may not pack objects densely; a chunk may either be an object or a
1405 // non-object.
1406 virtual HeapWord* block_start(const void* addr) const;
1408 // Requires "addr" to be the start of a chunk, and returns its size.
1409 // "addr + size" is required to be the start of a new chunk, or the end
1410 // of the active area of the heap.
1411 virtual size_t block_size(const HeapWord* addr) const;
1413 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1414 // the block is an object.
1415 virtual bool block_is_obj(const HeapWord* addr) const;
1417 // Does this heap support heap inspection? (+PrintClassHistogram)
1418 virtual bool supports_heap_inspection() const { return true; }
1420 // Section on thread-local allocation buffers (TLABs)
1421 // See CollectedHeap for semantics.
1423 bool supports_tlab_allocation() const;
1424 size_t tlab_capacity(Thread* ignored) const;
1425 size_t tlab_used(Thread* ignored) const;
1426 size_t max_tlab_size() const;
1427 size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1429 // Can a compiler initialize a new object without store barriers?
1430 // This permission only extends from the creation of a new object
1431 // via a TLAB up to the first subsequent safepoint. If such permission
1432 // is granted for this heap type, the compiler promises to call
1433 // defer_store_barrier() below on any slow path allocation of
1434 // a new object for which such initializing store barriers will
1435 // have been elided. G1, like CMS, allows this, but should be
1436 // ready to provide a compensating write barrier as necessary
1437 // if that storage came out of a non-young region. The efficiency
1438 // of this implementation depends crucially on being able to
1439 // answer very efficiently in constant time whether a piece of
1440 // storage in the heap comes from a young region or not.
1441 // See ReduceInitialCardMarks.
1442 virtual bool can_elide_tlab_store_barriers() const {
1443 return true;
1444 }
1446 virtual bool card_mark_must_follow_store() const {
1447 return true;
1448 }
1450 inline bool is_in_young(const oop obj);
1452 #ifdef ASSERT
1453 virtual bool is_in_partial_collection(const void* p);
1454 #endif
1456 virtual bool is_scavengable(const void* addr);
1458 // We don't need barriers for initializing stores to objects
1459 // in the young gen: for the SATB pre-barrier, there is no
1460 // pre-value that needs to be remembered; for the remembered-set
1461 // update logging post-barrier, we don't maintain remembered set
1462 // information for young gen objects.
1463 virtual inline bool can_elide_initializing_store_barrier(oop new_obj);
1465 // Returns "true" iff the given word_size is "very large".
1466 static bool isHumongous(size_t word_size) {
1467 // Note this has to be strictly greater-than as the TLABs
1468 // are capped at the humongous thresold and we want to
1469 // ensure that we don't try to allocate a TLAB as
1470 // humongous and that we don't allocate a humongous
1471 // object in a TLAB.
1472 return word_size > _humongous_object_threshold_in_words;
1473 }
1475 // Update mod union table with the set of dirty cards.
1476 void updateModUnion();
1478 // Set the mod union bits corresponding to the given memRegion. Note
1479 // that this is always a safe operation, since it doesn't clear any
1480 // bits.
1481 void markModUnionRange(MemRegion mr);
1483 // Records the fact that a marking phase is no longer in progress.
1484 void set_marking_complete() {
1485 _mark_in_progress = false;
1486 }
1487 void set_marking_started() {
1488 _mark_in_progress = true;
1489 }
1490 bool mark_in_progress() {
1491 return _mark_in_progress;
1492 }
1494 // Print the maximum heap capacity.
1495 virtual size_t max_capacity() const;
1497 virtual jlong millis_since_last_gc();
1500 // Convenience function to be used in situations where the heap type can be
1501 // asserted to be this type.
1502 static G1CollectedHeap* heap();
1504 void set_region_short_lived_locked(HeapRegion* hr);
1505 // add appropriate methods for any other surv rate groups
1507 YoungList* young_list() const { return _young_list; }
1509 // debugging
1510 bool check_young_list_well_formed() {
1511 return _young_list->check_list_well_formed();
1512 }
1514 bool check_young_list_empty(bool check_heap,
1515 bool check_sample = true);
1517 // *** Stuff related to concurrent marking. It's not clear to me that so
1518 // many of these need to be public.
1520 // The functions below are helper functions that a subclass of
1521 // "CollectedHeap" can use in the implementation of its virtual
1522 // functions.
1523 // This performs a concurrent marking of the live objects in a
1524 // bitmap off to the side.
1525 void doConcurrentMark();
1527 bool isMarkedPrev(oop obj) const;
1528 bool isMarkedNext(oop obj) const;
1530 // Determine if an object is dead, given the object and also
1531 // the region to which the object belongs. An object is dead
1532 // iff a) it was not allocated since the last mark and b) it
1533 // is not marked.
1535 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1536 return
1537 !hr->obj_allocated_since_prev_marking(obj) &&
1538 !isMarkedPrev(obj);
1539 }
1541 // This function returns true when an object has been
1542 // around since the previous marking and hasn't yet
1543 // been marked during this marking.
1545 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1546 return
1547 !hr->obj_allocated_since_next_marking(obj) &&
1548 !isMarkedNext(obj);
1549 }
1551 // Determine if an object is dead, given only the object itself.
1552 // This will find the region to which the object belongs and
1553 // then call the region version of the same function.
1555 // Added if it is NULL it isn't dead.
1557 inline bool is_obj_dead(const oop obj) const;
1559 inline bool is_obj_ill(const oop obj) const;
1561 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo);
1562 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo);
1563 bool is_marked(oop obj, VerifyOption vo);
1564 const char* top_at_mark_start_str(VerifyOption vo);
1566 ConcurrentMark* concurrent_mark() const { return _cm; }
1568 // Refinement
1570 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1572 // The dirty cards region list is used to record a subset of regions
1573 // whose cards need clearing. The list if populated during the
1574 // remembered set scanning and drained during the card table
1575 // cleanup. Although the methods are reentrant, population/draining
1576 // phases must not overlap. For synchronization purposes the last
1577 // element on the list points to itself.
1578 HeapRegion* _dirty_cards_region_list;
1579 void push_dirty_cards_region(HeapRegion* hr);
1580 HeapRegion* pop_dirty_cards_region();
1582 // Optimized nmethod scanning support routines
1584 // Register the given nmethod with the G1 heap
1585 virtual void register_nmethod(nmethod* nm);
1587 // Unregister the given nmethod from the G1 heap
1588 virtual void unregister_nmethod(nmethod* nm);
1590 // Migrate the nmethods in the code root lists of the regions
1591 // in the collection set to regions in to-space. In the event
1592 // of an evacuation failure, nmethods that reference objects
1593 // that were not successfullly evacuated are not migrated.
1594 void migrate_strong_code_roots();
1596 // Free up superfluous code root memory.
1597 void purge_code_root_memory();
1599 // During an initial mark pause, mark all the code roots that
1600 // point into regions *not* in the collection set.
1601 void mark_strong_code_roots(uint worker_id);
1603 // Rebuild the stong code root lists for each region
1604 // after a full GC
1605 void rebuild_strong_code_roots();
1607 // Delete entries for dead interned string and clean up unreferenced symbols
1608 // in symbol table, possibly in parallel.
1609 void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true);
1611 // Redirty logged cards in the refinement queue.
1612 void redirty_logged_cards();
1613 // Verification
1615 // The following is just to alert the verification code
1616 // that a full collection has occurred and that the
1617 // remembered sets are no longer up to date.
1618 bool _full_collection;
1619 void set_full_collection() { _full_collection = true;}
1620 void clear_full_collection() {_full_collection = false;}
1621 bool full_collection() {return _full_collection;}
1623 // Perform any cleanup actions necessary before allowing a verification.
1624 virtual void prepare_for_verify();
1626 // Perform verification.
1628 // vo == UsePrevMarking -> use "prev" marking information,
1629 // vo == UseNextMarking -> use "next" marking information
1630 // vo == UseMarkWord -> use the mark word in the object header
1631 //
1632 // NOTE: Only the "prev" marking information is guaranteed to be
1633 // consistent most of the time, so most calls to this should use
1634 // vo == UsePrevMarking.
1635 // Currently, there is only one case where this is called with
1636 // vo == UseNextMarking, which is to verify the "next" marking
1637 // information at the end of remark.
1638 // Currently there is only one place where this is called with
1639 // vo == UseMarkWord, which is to verify the marking during a
1640 // full GC.
1641 void verify(bool silent, VerifyOption vo);
1643 // Override; it uses the "prev" marking information
1644 virtual void verify(bool silent);
1646 // The methods below are here for convenience and dispatch the
1647 // appropriate method depending on value of the given VerifyOption
1648 // parameter. The values for that parameter, and their meanings,
1649 // are the same as those above.
1651 bool is_obj_dead_cond(const oop obj,
1652 const HeapRegion* hr,
1653 const VerifyOption vo) const;
1655 bool is_obj_dead_cond(const oop obj,
1656 const VerifyOption vo) const;
1658 // Printing
1660 virtual void print_on(outputStream* st) const;
1661 virtual void print_extended_on(outputStream* st) const;
1662 virtual void print_on_error(outputStream* st) const;
1664 virtual void print_gc_threads_on(outputStream* st) const;
1665 virtual void gc_threads_do(ThreadClosure* tc) const;
1667 // Override
1668 void print_tracing_info() const;
1670 // The following two methods are helpful for debugging RSet issues.
1671 void print_cset_rsets() PRODUCT_RETURN;
1672 void print_all_rsets() PRODUCT_RETURN;
1674 public:
1675 size_t pending_card_num();
1676 size_t cards_scanned();
1678 protected:
1679 size_t _max_heap_capacity;
1680 };
1682 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
1683 private:
1684 bool _retired;
1686 public:
1687 G1ParGCAllocBuffer(size_t gclab_word_size);
1688 virtual ~G1ParGCAllocBuffer() {
1689 guarantee(_retired, "Allocation buffer has not been retired");
1690 }
1692 virtual void set_buf(HeapWord* buf) {
1693 ParGCAllocBuffer::set_buf(buf);
1694 _retired = false;
1695 }
1697 virtual void retire(bool end_of_gc, bool retain) {
1698 if (_retired) {
1699 return;
1700 }
1701 ParGCAllocBuffer::retire(end_of_gc, retain);
1702 _retired = true;
1703 }
1704 };
1706 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP