1 /*
2 * Copyright (c) 2001, 2019, 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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24
25 #ifndef SHARE_GC_G1_G1COLLECTEDHEAP_HPP
26 #define SHARE_GC_G1_G1COLLECTEDHEAP_HPP
27
28 #include "gc/g1/g1BarrierSet.hpp"
29 #include "gc/g1/g1BiasedArray.hpp"
30 #include "gc/g1/g1CardTable.hpp"
31 #include "gc/g1/g1CollectionSet.hpp"
32 #include "gc/g1/g1CollectorState.hpp"
33 #include "gc/g1/g1ConcurrentMark.hpp"
34 #include "gc/g1/g1EdenRegions.hpp"
35 #include "gc/g1/g1EvacFailure.hpp"
36 #include "gc/g1/g1EvacStats.hpp"
37 #include "gc/g1/g1EvacuationInfo.hpp"
38 #include "gc/g1/g1GCPhaseTimes.hpp"
39 #include "gc/g1/g1HeapTransition.hpp"
40 #include "gc/g1/g1HeapVerifier.hpp"
41 #include "gc/g1/g1HRPrinter.hpp"
42 #include "gc/g1/g1HeapRegionAttr.hpp"
43 #include "gc/g1/g1MonitoringSupport.hpp"
44 #include "gc/g1/g1RedirtyCardsQueue.hpp"
45 #include "gc/g1/g1SurvivorRegions.hpp"
46 #include "gc/g1/g1YCTypes.hpp"
47 #include "gc/g1/heapRegionManager.hpp"
48 #include "gc/g1/heapRegionSet.hpp"
49 #include "gc/g1/heterogeneousHeapRegionManager.hpp"
50 #include "gc/shared/barrierSet.hpp"
51 #include "gc/shared/collectedHeap.hpp"
52 #include "gc/shared/gcHeapSummary.hpp"
53 #include "gc/shared/plab.hpp"
54 #include "gc/shared/preservedMarks.hpp"
55 #include "gc/shared/softRefPolicy.hpp"
56 #include "memory/memRegion.hpp"
57 #include "utilities/stack.hpp"
58
59 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
60 // It uses the "Garbage First" heap organization and algorithm, which
61 // may combine concurrent marking with parallel, incremental compaction of
62 // heap subsets that will yield large amounts of garbage.
63
64 // Forward declarations
65 class HeapRegion;
66 class GenerationSpec;
67 class G1ParScanThreadState;
68 class G1ParScanThreadStateSet;
69 class G1ParScanThreadState;
70 class MemoryPool;
71 class MemoryManager;
72 class ObjectClosure;
73 class SpaceClosure;
74 class CompactibleSpaceClosure;
75 class Space;
76 class G1CardTableEntryClosure;
77 class G1CollectionSet;
78 class G1Policy;
79 class G1HotCardCache;
80 class G1RemSet;
81 class G1YoungRemSetSamplingThread;
82 class G1ConcurrentMark;
83 class G1ConcurrentMarkThread;
84 class G1ConcurrentRefine;
85 class GenerationCounters;
86 class STWGCTimer;
87 class G1NewTracer;
88 class EvacuationFailedInfo;
89 class nmethod;
90 class WorkGang;
91 class G1Allocator;
92 class G1ArchiveAllocator;
93 class G1FullGCScope;
94 class G1HeapVerifier;
95 class G1HeapSizingPolicy;
96 class G1HeapSummary;
97 class G1EvacSummary;
98
99 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue;
100 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
101
102 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
103 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
104
105 // The G1 STW is alive closure.
106 // An instance is embedded into the G1CH and used as the
107 // (optional) _is_alive_non_header closure in the STW
108 // reference processor. It is also extensively used during
109 // reference processing during STW evacuation pauses.
110 class G1STWIsAliveClosure : public BoolObjectClosure {
111 G1CollectedHeap* _g1h;
112 public:
113 G1STWIsAliveClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
114 bool do_object_b(oop p);
115 };
116
117 class G1STWSubjectToDiscoveryClosure : public BoolObjectClosure {
118 G1CollectedHeap* _g1h;
119 public:
120 G1STWSubjectToDiscoveryClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
121 bool do_object_b(oop p);
122 };
123
124 class G1RegionMappingChangedListener : public G1MappingChangedListener {
125 private:
126 void reset_from_card_cache(uint start_idx, size_t num_regions);
127 public:
128 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
129 };
130
131 class G1CollectedHeap : public CollectedHeap {
132 friend class VM_CollectForMetadataAllocation;
133 friend class VM_G1CollectForAllocation;
134 friend class VM_G1CollectFull;
135 friend class VM_G1TryInitiateConcMark;
136 friend class VMStructs;
137 friend class MutatorAllocRegion;
138 friend class G1FullCollector;
139 friend class G1GCAllocRegion;
140 friend class G1HeapVerifier;
141
142 // Closures used in implementation.
143 friend class G1ParScanThreadState;
144 friend class G1ParScanThreadStateSet;
145 friend class G1EvacuateRegionsTask;
146 friend class G1PLABAllocator;
147
148 // Other related classes.
149 friend class HeapRegionClaimer;
150
151 // Testing classes.
152 friend class G1CheckRegionAttrTableClosure;
153
154 private:
155 G1YoungRemSetSamplingThread* _young_gen_sampling_thread;
156
157 WorkGang* _workers;
158 G1CardTable* _card_table;
159
160 SoftRefPolicy _soft_ref_policy;
161
162 static size_t _humongous_object_threshold_in_words;
163
164 // These sets keep track of old, archive and humongous regions respectively.
165 HeapRegionSet _old_set;
166 HeapRegionSet _archive_set;
167 HeapRegionSet _humongous_set;
168
169 void eagerly_reclaim_humongous_regions();
170 // Start a new incremental collection set for the next pause.
171 void start_new_collection_set();
172
173 // The block offset table for the G1 heap.
174 G1BlockOffsetTable* _bot;
175
176 // Tears down the region sets / lists so that they are empty and the
177 // regions on the heap do not belong to a region set / list. The
178 // only exception is the humongous set which we leave unaltered. If
179 // free_list_only is true, it will only tear down the master free
180 // list. It is called before a Full GC (free_list_only == false) or
181 // before heap shrinking (free_list_only == true).
182 void tear_down_region_sets(bool free_list_only);
183
184 // Rebuilds the region sets / lists so that they are repopulated to
185 // reflect the contents of the heap. The only exception is the
186 // humongous set which was not torn down in the first place. If
187 // free_list_only is true, it will only rebuild the master free
188 // list. It is called after a Full GC (free_list_only == false) or
189 // after heap shrinking (free_list_only == true).
190 void rebuild_region_sets(bool free_list_only);
191
192 // Callback for region mapping changed events.
193 G1RegionMappingChangedListener _listener;
194
195 // The sequence of all heap regions in the heap.
196 HeapRegionManager* _hrm;
197
198 // Manages all allocations with regions except humongous object allocations.
199 G1Allocator* _allocator;
200
201 // Manages all heap verification.
202 G1HeapVerifier* _verifier;
203
204 // Outside of GC pauses, the number of bytes used in all regions other
205 // than the current allocation region(s).
206 volatile size_t _summary_bytes_used;
207
208 void increase_used(size_t bytes);
209 void decrease_used(size_t bytes);
210
211 void set_used(size_t bytes);
212
213 // Class that handles archive allocation ranges.
214 G1ArchiveAllocator* _archive_allocator;
215
216 // GC allocation statistics policy for survivors.
217 G1EvacStats _survivor_evac_stats;
218
219 // GC allocation statistics policy for tenured objects.
220 G1EvacStats _old_evac_stats;
221
222 // It specifies whether we should attempt to expand the heap after a
223 // region allocation failure. If heap expansion fails we set this to
224 // false so that we don't re-attempt the heap expansion (it's likely
225 // that subsequent expansion attempts will also fail if one fails).
226 // Currently, it is only consulted during GC and it's reset at the
227 // start of each GC.
228 bool _expand_heap_after_alloc_failure;
229
230 // Helper for monitoring and management support.
231 G1MonitoringSupport* _g1mm;
232
233 // Records whether the region at the given index is (still) a
234 // candidate for eager reclaim. Only valid for humongous start
235 // regions; other regions have unspecified values. Humongous start
236 // regions are initialized at start of collection pause, with
237 // candidates removed from the set as they are found reachable from
238 // roots or the young generation.
239 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> {
240 protected:
241 bool default_value() const { return false; }
242 public:
243 void clear() { G1BiasedMappedArray<bool>::clear(); }
244 void set_candidate(uint region, bool value) {
245 set_by_index(region, value);
246 }
247 bool is_candidate(uint region) {
248 return get_by_index(region);
249 }
250 };
251
252 HumongousReclaimCandidates _humongous_reclaim_candidates;
253 // Stores whether during humongous object registration we found candidate regions.
254 // If not, we can skip a few steps.
255 bool _has_humongous_reclaim_candidates;
256
257 G1HRPrinter _hr_printer;
258
259 // It decides whether an explicit GC should start a concurrent cycle
260 // instead of doing a STW GC. Currently, a concurrent cycle is
261 // explicitly started if:
262 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
263 // (b) cause == _g1_humongous_allocation
264 // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
265 // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent.
266 // (e) cause == _wb_conc_mark
267 bool should_do_concurrent_full_gc(GCCause::Cause cause);
268
269 // Attempt to start a concurrent cycle with the indicated cause.
270 // precondition: should_do_concurrent_full_gc(cause)
271 bool try_collect_concurrently(GCCause::Cause cause,
272 uint gc_counter,
273 uint old_marking_started_before);
274
275 // Return true if should upgrade to full gc after an incremental one.
276 bool should_upgrade_to_full_gc(GCCause::Cause cause);
277
278 // indicates whether we are in young or mixed GC mode
279 G1CollectorState _collector_state;
280
281 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
282 // concurrent cycles) we have started.
283 volatile uint _old_marking_cycles_started;
284
285 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
286 // concurrent cycles) we have completed.
287 volatile uint _old_marking_cycles_completed;
288
289 // This is a non-product method that is helpful for testing. It is
290 // called at the end of a GC and artificially expands the heap by
291 // allocating a number of dead regions. This way we can induce very
292 // frequent marking cycles and stress the cleanup / concurrent
293 // cleanup code more (as all the regions that will be allocated by
294 // this method will be found dead by the marking cycle).
295 void allocate_dummy_regions() PRODUCT_RETURN;
296
297 // If the HR printer is active, dump the state of the regions in the
298 // heap after a compaction.
299 void print_hrm_post_compaction();
300
301 // Create a memory mapper for auxiliary data structures of the given size and
302 // translation factor.
303 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description,
304 size_t size,
305 size_t translation_factor);
306
307 void trace_heap(GCWhen::Type when, const GCTracer* tracer);
308
309 // These are macros so that, if the assert fires, we get the correct
310 // line number, file, etc.
311
312 #define heap_locking_asserts_params(_extra_message_) \
313 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
314 (_extra_message_), \
315 BOOL_TO_STR(Heap_lock->owned_by_self()), \
316 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
317 BOOL_TO_STR(Thread::current()->is_VM_thread())
318
319 #define assert_heap_locked() \
320 do { \
321 assert(Heap_lock->owned_by_self(), \
322 heap_locking_asserts_params("should be holding the Heap_lock")); \
323 } while (0)
324
325 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
326 do { \
327 assert(Heap_lock->owned_by_self() || \
328 (SafepointSynchronize::is_at_safepoint() && \
329 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
330 heap_locking_asserts_params("should be holding the Heap_lock or " \
331 "should be at a safepoint")); \
332 } while (0)
333
334 #define assert_heap_locked_and_not_at_safepoint() \
335 do { \
336 assert(Heap_lock->owned_by_self() && \
337 !SafepointSynchronize::is_at_safepoint(), \
338 heap_locking_asserts_params("should be holding the Heap_lock and " \
339 "should not be at a safepoint")); \
340 } while (0)
341
342 #define assert_heap_not_locked() \
343 do { \
344 assert(!Heap_lock->owned_by_self(), \
345 heap_locking_asserts_params("should not be holding the Heap_lock")); \
346 } while (0)
347
348 #define assert_heap_not_locked_and_not_at_safepoint() \
349 do { \
350 assert(!Heap_lock->owned_by_self() && \
351 !SafepointSynchronize::is_at_safepoint(), \
352 heap_locking_asserts_params("should not be holding the Heap_lock and " \
353 "should not be at a safepoint")); \
354 } while (0)
355
356 #define assert_at_safepoint_on_vm_thread() \
357 do { \
358 assert_at_safepoint(); \
359 assert(Thread::current_or_null() != NULL, "no current thread"); \
360 assert(Thread::current()->is_VM_thread(), "current thread is not VM thread"); \
361 } while (0)
362
363 #ifdef ASSERT
364 #define assert_used_and_recalculate_used_equal(g1h) \
365 do { \
366 size_t cur_used_bytes = g1h->used(); \
367 size_t recal_used_bytes = g1h->recalculate_used(); \
368 assert(cur_used_bytes == recal_used_bytes, "Used(" SIZE_FORMAT ") is not" \
369 " same as recalculated used(" SIZE_FORMAT ").", \
370 cur_used_bytes, recal_used_bytes); \
371 } while (0)
372 #else
373 #define assert_used_and_recalculate_used_equal(g1h) do {} while(0)
374 #endif
375
376 const char* young_gc_name() const;
377
378 // The young region list.
379 G1EdenRegions _eden;
380 G1SurvivorRegions _survivor;
381
382 STWGCTimer* _gc_timer_stw;
383
384 G1NewTracer* _gc_tracer_stw;
385
386 // The current policy object for the collector.
387 G1Policy* _policy;
388 G1HeapSizingPolicy* _heap_sizing_policy;
389
390 G1CollectionSet _collection_set;
391
392 // Try to allocate a single non-humongous HeapRegion sufficient for
393 // an allocation of the given word_size. If do_expand is true,
394 // attempt to expand the heap if necessary to satisfy the allocation
395 // request. 'type' takes the type of region to be allocated. (Use constants
396 // Old, Eden, Humongous, Survivor defined in HeapRegionType.)
397 HeapRegion* new_region(size_t word_size, HeapRegionType type, bool do_expand);
398
399 // Initialize a contiguous set of free regions of length num_regions
400 // and starting at index first so that they appear as a single
401 // humongous region.
402 HeapWord* humongous_obj_allocate_initialize_regions(uint first,
403 uint num_regions,
404 size_t word_size);
405
406 // Attempt to allocate a humongous object of the given size. Return
407 // NULL if unsuccessful.
408 HeapWord* humongous_obj_allocate(size_t word_size);
409
410 // The following two methods, allocate_new_tlab() and
411 // mem_allocate(), are the two main entry points from the runtime
412 // into the G1's allocation routines. They have the following
413 // assumptions:
414 //
415 // * They should both be called outside safepoints.
416 //
417 // * They should both be called without holding the Heap_lock.
418 //
419 // * All allocation requests for new TLABs should go to
420 // allocate_new_tlab().
421 //
422 // * All non-TLAB allocation requests should go to mem_allocate().
423 //
424 // * If either call cannot satisfy the allocation request using the
425 // current allocating region, they will try to get a new one. If
426 // this fails, they will attempt to do an evacuation pause and
427 // retry the allocation.
428 //
429 // * If all allocation attempts fail, even after trying to schedule
430 // an evacuation pause, allocate_new_tlab() will return NULL,
431 // whereas mem_allocate() will attempt a heap expansion and/or
432 // schedule a Full GC.
433 //
434 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
435 // should never be called with word_size being humongous. All
436 // humongous allocation requests should go to mem_allocate() which
437 // will satisfy them with a special path.
438
439 virtual HeapWord* allocate_new_tlab(size_t min_size,
440 size_t requested_size,
441 size_t* actual_size);
442
443 virtual HeapWord* mem_allocate(size_t word_size,
444 bool* gc_overhead_limit_was_exceeded);
445
446 // First-level mutator allocation attempt: try to allocate out of
447 // the mutator alloc region without taking the Heap_lock. This
448 // should only be used for non-humongous allocations.
449 inline HeapWord* attempt_allocation(size_t min_word_size,
450 size_t desired_word_size,
451 size_t* actual_word_size);
452
453 // Second-level mutator allocation attempt: take the Heap_lock and
454 // retry the allocation attempt, potentially scheduling a GC
455 // pause. This should only be used for non-humongous allocations.
456 HeapWord* attempt_allocation_slow(size_t word_size);
457
458 // Takes the Heap_lock and attempts a humongous allocation. It can
459 // potentially schedule a GC pause.
460 HeapWord* attempt_allocation_humongous(size_t word_size);
461
462 // Allocation attempt that should be called during safepoints (e.g.,
463 // at the end of a successful GC). expect_null_mutator_alloc_region
464 // specifies whether the mutator alloc region is expected to be NULL
465 // or not.
466 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
467 bool expect_null_mutator_alloc_region);
468
469 // These methods are the "callbacks" from the G1AllocRegion class.
470
471 // For mutator alloc regions.
472 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
473 void retire_mutator_alloc_region(HeapRegion* alloc_region,
474 size_t allocated_bytes);
475
476 // For GC alloc regions.
477 bool has_more_regions(G1HeapRegionAttr dest);
478 HeapRegion* new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest);
479 void retire_gc_alloc_region(HeapRegion* alloc_region,
480 size_t allocated_bytes, G1HeapRegionAttr dest);
481
482 // - if explicit_gc is true, the GC is for a System.gc() etc,
483 // otherwise it's for a failed allocation.
484 // - if clear_all_soft_refs is true, all soft references should be
485 // cleared during the GC.
486 // - it returns false if it is unable to do the collection due to the
487 // GC locker being active, true otherwise.
488 bool do_full_collection(bool explicit_gc,
489 bool clear_all_soft_refs);
490
491 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread.
492 virtual void do_full_collection(bool clear_all_soft_refs);
493
494 // Callback from VM_G1CollectForAllocation operation.
495 // This function does everything necessary/possible to satisfy a
496 // failed allocation request (including collection, expansion, etc.)
497 HeapWord* satisfy_failed_allocation(size_t word_size,
498 bool* succeeded);
499 // Internal helpers used during full GC to split it up to
500 // increase readability.
501 void abort_concurrent_cycle();
502 void verify_before_full_collection(bool explicit_gc);
503 void prepare_heap_for_full_collection();
504 void prepare_heap_for_mutators();
505 void abort_refinement();
506 void verify_after_full_collection();
507 void print_heap_after_full_collection(G1HeapTransition* heap_transition);
508
509 // Helper method for satisfy_failed_allocation()
510 HeapWord* satisfy_failed_allocation_helper(size_t word_size,
511 bool do_gc,
512 bool clear_all_soft_refs,
513 bool expect_null_mutator_alloc_region,
514 bool* gc_succeeded);
515
516 // Attempting to expand the heap sufficiently
517 // to support an allocation of the given "word_size". If
518 // successful, perform the allocation and return the address of the
519 // allocated block, or else "NULL".
520 HeapWord* expand_and_allocate(size_t word_size);
521
522 // Process any reference objects discovered.
523 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states);
524
525 // If during an initial mark pause we may install a pending list head which is not
526 // otherwise reachable ensure that it is marked in the bitmap for concurrent marking
527 // to discover.
528 void make_pending_list_reachable();
529
530 // Merges the information gathered on a per-thread basis for all worker threads
531 // during GC into global variables.
532 void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states);
533 public:
534 G1YoungRemSetSamplingThread* sampling_thread() const { return _young_gen_sampling_thread; }
535
536 WorkGang* workers() const { return _workers; }
537
538 // Runs the given AbstractGangTask with the current active workers, returning the
539 // total time taken.
540 Tickspan run_task(AbstractGangTask* task);
541
542 G1Allocator* allocator() {
543 return _allocator;
544 }
545
546 G1HeapVerifier* verifier() {
547 return _verifier;
548 }
549
550 G1MonitoringSupport* g1mm() {
551 assert(_g1mm != NULL, "should have been initialized");
552 return _g1mm;
553 }
554
555 void resize_heap_if_necessary();
556
557 // Expand the garbage-first heap by at least the given size (in bytes!).
558 // Returns true if the heap was expanded by the requested amount;
559 // false otherwise.
560 // (Rounds up to a HeapRegion boundary.)
561 bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL);
562
563 // Returns the PLAB statistics for a given destination.
564 inline G1EvacStats* alloc_buffer_stats(G1HeapRegionAttr dest);
565
566 // Determines PLAB size for a given destination.
567 inline size_t desired_plab_sz(G1HeapRegionAttr dest);
568
569 // Do anything common to GC's.
570 void gc_prologue(bool full);
571 void gc_epilogue(bool full);
572
573 // Does the given region fulfill remembered set based eager reclaim candidate requirements?
574 bool is_potential_eager_reclaim_candidate(HeapRegion* r) const;
575
576 // Modify the reclaim candidate set and test for presence.
577 // These are only valid for starts_humongous regions.
578 inline void set_humongous_reclaim_candidate(uint region, bool value);
579 inline bool is_humongous_reclaim_candidate(uint region);
580
581 // Remove from the reclaim candidate set. Also remove from the
582 // collection set so that later encounters avoid the slow path.
583 inline void set_humongous_is_live(oop obj);
584
585 // Register the given region to be part of the collection set.
586 inline void register_humongous_region_with_region_attr(uint index);
587 // Update region attributes table with information about all regions.
588 void register_regions_with_region_attr();
589 // We register a region with the fast "in collection set" test. We
590 // simply set to true the array slot corresponding to this region.
591 void register_young_region_with_region_attr(HeapRegion* r) {
592 _region_attr.set_in_young(r->hrm_index());
593 }
594 inline void register_region_with_region_attr(HeapRegion* r);
595 inline void register_old_region_with_region_attr(HeapRegion* r);
596 inline void register_optional_region_with_region_attr(HeapRegion* r);
597
598 void clear_region_attr(const HeapRegion* hr) {
599 _region_attr.clear(hr);
600 }
601
602 void clear_region_attr() {
603 _region_attr.clear();
604 }
605
606 // Verify that the G1RegionAttr remset tracking corresponds to actual remset tracking
607 // for all regions.
608 void verify_region_attr_remset_update() PRODUCT_RETURN;
609
610 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause);
611
612 // This is called at the start of either a concurrent cycle or a Full
613 // GC to update the number of old marking cycles started.
614 void increment_old_marking_cycles_started();
615
616 // This is called at the end of either a concurrent cycle or a Full
617 // GC to update the number of old marking cycles completed. Those two
618 // can happen in a nested fashion, i.e., we start a concurrent
619 // cycle, a Full GC happens half-way through it which ends first,
620 // and then the cycle notices that a Full GC happened and ends
621 // too. The concurrent parameter is a boolean to help us do a bit
622 // tighter consistency checking in the method. If concurrent is
623 // false, the caller is the inner caller in the nesting (i.e., the
624 // Full GC). If concurrent is true, the caller is the outer caller
625 // in this nesting (i.e., the concurrent cycle). Further nesting is
626 // not currently supported. The end of this call also notifies
627 // the G1FullGCCount_lock in case a Java thread is waiting for a full
628 // GC to happen (e.g., it called System.gc() with
629 // +ExplicitGCInvokesConcurrent).
630 void increment_old_marking_cycles_completed(bool concurrent);
631
632 uint old_marking_cycles_completed() {
633 return _old_marking_cycles_completed;
634 }
635
636 G1HRPrinter* hr_printer() { return &_hr_printer; }
637
638 // Allocates a new heap region instance.
639 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr);
640
641 // Allocate the highest free region in the reserved heap. This will commit
642 // regions as necessary.
643 HeapRegion* alloc_highest_free_region();
644
645 // Frees a non-humongous region by initializing its contents and
646 // adding it to the free list that's passed as a parameter (this is
647 // usually a local list which will be appended to the master free
648 // list later). The used bytes of freed regions are accumulated in
649 // pre_used. If skip_remset is true, the region's RSet will not be freed
650 // up. If skip_hot_card_cache is true, the region's hot card cache will not
651 // be freed up. The assumption is that this will be done later.
652 // The locked parameter indicates if the caller has already taken
653 // care of proper synchronization. This may allow some optimizations.
654 void free_region(HeapRegion* hr,
655 FreeRegionList* free_list,
656 bool skip_remset,
657 bool skip_hot_card_cache = false,
658 bool locked = false);
659
660 // It dirties the cards that cover the block so that the post
661 // write barrier never queues anything when updating objects on this
662 // block. It is assumed (and in fact we assert) that the block
663 // belongs to a young region.
664 inline void dirty_young_block(HeapWord* start, size_t word_size);
665
666 // Frees a humongous region by collapsing it into individual regions
667 // and calling free_region() for each of them. The freed regions
668 // will be added to the free list that's passed as a parameter (this
669 // is usually a local list which will be appended to the master free
670 // list later).
671 // The method assumes that only a single thread is ever calling
672 // this for a particular region at once.
673 void free_humongous_region(HeapRegion* hr,
674 FreeRegionList* free_list);
675
676 // Facility for allocating in 'archive' regions in high heap memory and
677 // recording the allocated ranges. These should all be called from the
678 // VM thread at safepoints, without the heap lock held. They can be used
679 // to create and archive a set of heap regions which can be mapped at the
680 // same fixed addresses in a subsequent JVM invocation.
681 void begin_archive_alloc_range(bool open = false);
682
683 // Check if the requested size would be too large for an archive allocation.
684 bool is_archive_alloc_too_large(size_t word_size);
685
686 // Allocate memory of the requested size from the archive region. This will
687 // return NULL if the size is too large or if no memory is available. It
688 // does not trigger a garbage collection.
689 HeapWord* archive_mem_allocate(size_t word_size);
690
691 // Optionally aligns the end address and returns the allocated ranges in
692 // an array of MemRegions in order of ascending addresses.
693 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
694 size_t end_alignment_in_bytes = 0);
695
696 // Facility for allocating a fixed range within the heap and marking
697 // the containing regions as 'archive'. For use at JVM init time, when the
698 // caller may mmap archived heap data at the specified range(s).
699 // Verify that the MemRegions specified in the argument array are within the
700 // reserved heap.
701 bool check_archive_addresses(MemRegion* range, size_t count);
702
703 // Commit the appropriate G1 regions containing the specified MemRegions
704 // and mark them as 'archive' regions. The regions in the array must be
705 // non-overlapping and in order of ascending address.
706 bool alloc_archive_regions(MemRegion* range, size_t count, bool open);
707
708 // Insert any required filler objects in the G1 regions around the specified
709 // ranges to make the regions parseable. This must be called after
710 // alloc_archive_regions, and after class loading has occurred.
711 void fill_archive_regions(MemRegion* range, size_t count);
712
713 // For each of the specified MemRegions, uncommit the containing G1 regions
714 // which had been allocated by alloc_archive_regions. This should be called
715 // rather than fill_archive_regions at JVM init time if the archive file
716 // mapping failed, with the same non-overlapping and sorted MemRegion array.
717 void dealloc_archive_regions(MemRegion* range, size_t count, bool is_open);
718
719 oop materialize_archived_object(oop obj);
720
721 private:
722
723 // Shrink the garbage-first heap by at most the given size (in bytes!).
724 // (Rounds down to a HeapRegion boundary.)
725 void shrink(size_t expand_bytes);
726 void shrink_helper(size_t expand_bytes);
727
728 #if TASKQUEUE_STATS
729 static void print_taskqueue_stats_hdr(outputStream* const st);
730 void print_taskqueue_stats() const;
731 void reset_taskqueue_stats();
732 #endif // TASKQUEUE_STATS
733
734 // Schedule the VM operation that will do an evacuation pause to
735 // satisfy an allocation request of word_size. *succeeded will
736 // return whether the VM operation was successful (it did do an
737 // evacuation pause) or not (another thread beat us to it or the GC
738 // locker was active). Given that we should not be holding the
739 // Heap_lock when we enter this method, we will pass the
740 // gc_count_before (i.e., total_collections()) as a parameter since
741 // it has to be read while holding the Heap_lock. Currently, both
742 // methods that call do_collection_pause() release the Heap_lock
743 // before the call, so it's easy to read gc_count_before just before.
744 HeapWord* do_collection_pause(size_t word_size,
745 uint gc_count_before,
746 bool* succeeded,
747 GCCause::Cause gc_cause);
748
749 void wait_for_root_region_scanning();
750
751 // The guts of the incremental collection pause, executed by the vm
752 // thread. It returns false if it is unable to do the collection due
753 // to the GC locker being active, true otherwise
754 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
755
756 G1HeapVerifier::G1VerifyType young_collection_verify_type() const;
757 void verify_before_young_collection(G1HeapVerifier::G1VerifyType type);
758 void verify_after_young_collection(G1HeapVerifier::G1VerifyType type);
759
760 void calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms);
761
762 // Actually do the work of evacuating the parts of the collection set.
763 void evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states);
764 void evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states);
765 private:
766 // Evacuate the next set of optional regions.
767 void evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states);
768
769 public:
770 void pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss);
771 void post_evacuate_collection_set(G1EvacuationInfo& evacuation_info,
772 G1RedirtyCardsQueueSet* rdcqs,
773 G1ParScanThreadStateSet* pss);
774
775 void expand_heap_after_young_collection();
776 // Update object copying statistics.
777 void record_obj_copy_mem_stats();
778
779 // The hot card cache for remembered set insertion optimization.
780 G1HotCardCache* _hot_card_cache;
781
782 // The g1 remembered set of the heap.
783 G1RemSet* _rem_set;
784
785 // After a collection pause, convert the regions in the collection set into free
786 // regions.
787 void free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words);
788
789 // Abandon the current collection set without recording policy
790 // statistics or updating free lists.
791 void abandon_collection_set(G1CollectionSet* collection_set);
792
793 // The concurrent marker (and the thread it runs in.)
794 G1ConcurrentMark* _cm;
795 G1ConcurrentMarkThread* _cm_thread;
796
797 // The concurrent refiner.
798 G1ConcurrentRefine* _cr;
799
800 // The parallel task queues
801 RefToScanQueueSet *_task_queues;
802
803 // True iff a evacuation has failed in the current collection.
804 bool _evacuation_failed;
805
806 EvacuationFailedInfo* _evacuation_failed_info_array;
807
808 // Failed evacuations cause some logical from-space objects to have
809 // forwarding pointers to themselves. Reset them.
810 void remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs);
811
812 // Restore the objects in the regions in the collection set after an
813 // evacuation failure.
814 void restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs);
815
816 PreservedMarksSet _preserved_marks_set;
817
818 // Preserve the mark of "obj", if necessary, in preparation for its mark
819 // word being overwritten with a self-forwarding-pointer.
820 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m);
821
822 #ifndef PRODUCT
823 // Support for forcing evacuation failures. Analogous to
824 // PromotionFailureALot for the other collectors.
825
826 // Records whether G1EvacuationFailureALot should be in effect
827 // for the current GC
828 bool _evacuation_failure_alot_for_current_gc;
829
830 // Used to record the GC number for interval checking when
831 // determining whether G1EvaucationFailureALot is in effect
832 // for the current GC.
833 size_t _evacuation_failure_alot_gc_number;
834
835 // Count of the number of evacuations between failures.
836 volatile size_t _evacuation_failure_alot_count;
837
838 // Set whether G1EvacuationFailureALot should be in effect
839 // for the current GC (based upon the type of GC and which
840 // command line flags are set);
841 inline bool evacuation_failure_alot_for_gc_type(bool for_young_gc,
842 bool during_initial_mark,
843 bool mark_or_rebuild_in_progress);
844
845 inline void set_evacuation_failure_alot_for_current_gc();
846
847 // Return true if it's time to cause an evacuation failure.
848 inline bool evacuation_should_fail();
849
850 // Reset the G1EvacuationFailureALot counters. Should be called at
851 // the end of an evacuation pause in which an evacuation failure occurred.
852 inline void reset_evacuation_should_fail();
853 #endif // !PRODUCT
854
855 // ("Weak") Reference processing support.
856 //
857 // G1 has 2 instances of the reference processor class. One
858 // (_ref_processor_cm) handles reference object discovery
859 // and subsequent processing during concurrent marking cycles.
860 //
861 // The other (_ref_processor_stw) handles reference object
862 // discovery and processing during full GCs and incremental
863 // evacuation pauses.
864 //
865 // During an incremental pause, reference discovery will be
866 // temporarily disabled for _ref_processor_cm and will be
867 // enabled for _ref_processor_stw. At the end of the evacuation
868 // pause references discovered by _ref_processor_stw will be
869 // processed and discovery will be disabled. The previous
870 // setting for reference object discovery for _ref_processor_cm
871 // will be re-instated.
872 //
873 // At the start of marking:
874 // * Discovery by the CM ref processor is verified to be inactive
875 // and it's discovered lists are empty.
876 // * Discovery by the CM ref processor is then enabled.
877 //
878 // At the end of marking:
879 // * Any references on the CM ref processor's discovered
880 // lists are processed (possibly MT).
881 //
882 // At the start of full GC we:
883 // * Disable discovery by the CM ref processor and
884 // empty CM ref processor's discovered lists
885 // (without processing any entries).
886 // * Verify that the STW ref processor is inactive and it's
887 // discovered lists are empty.
888 // * Temporarily set STW ref processor discovery as single threaded.
889 // * Temporarily clear the STW ref processor's _is_alive_non_header
890 // field.
891 // * Finally enable discovery by the STW ref processor.
892 //
893 // The STW ref processor is used to record any discovered
894 // references during the full GC.
895 //
896 // At the end of a full GC we:
897 // * Enqueue any reference objects discovered by the STW ref processor
898 // that have non-live referents. This has the side-effect of
899 // making the STW ref processor inactive by disabling discovery.
900 // * Verify that the CM ref processor is still inactive
901 // and no references have been placed on it's discovered
902 // lists (also checked as a precondition during initial marking).
903
904 // The (stw) reference processor...
905 ReferenceProcessor* _ref_processor_stw;
906
907 // During reference object discovery, the _is_alive_non_header
908 // closure (if non-null) is applied to the referent object to
909 // determine whether the referent is live. If so then the
910 // reference object does not need to be 'discovered' and can
911 // be treated as a regular oop. This has the benefit of reducing
912 // the number of 'discovered' reference objects that need to
913 // be processed.
914 //
915 // Instance of the is_alive closure for embedding into the
916 // STW reference processor as the _is_alive_non_header field.
917 // Supplying a value for the _is_alive_non_header field is
918 // optional but doing so prevents unnecessary additions to
919 // the discovered lists during reference discovery.
920 G1STWIsAliveClosure _is_alive_closure_stw;
921
922 G1STWSubjectToDiscoveryClosure _is_subject_to_discovery_stw;
923
924 // The (concurrent marking) reference processor...
925 ReferenceProcessor* _ref_processor_cm;
926
927 // Instance of the concurrent mark is_alive closure for embedding
928 // into the Concurrent Marking reference processor as the
929 // _is_alive_non_header field. Supplying a value for the
930 // _is_alive_non_header field is optional but doing so prevents
931 // unnecessary additions to the discovered lists during reference
932 // discovery.
933 G1CMIsAliveClosure _is_alive_closure_cm;
934
935 G1CMSubjectToDiscoveryClosure _is_subject_to_discovery_cm;
936 public:
937
938 RefToScanQueue *task_queue(uint i) const;
939
940 uint num_task_queues() const;
941
942 // Create a G1CollectedHeap.
943 // Must call the initialize method afterwards.
944 // May not return if something goes wrong.
945 G1CollectedHeap();
946
947 private:
948 jint initialize_concurrent_refinement();
949 jint initialize_young_gen_sampling_thread();
950 public:
951 // Initialize the G1CollectedHeap to have the initial and
952 // maximum sizes and remembered and barrier sets
953 // specified by the policy object.
954 jint initialize();
955
956 virtual void stop();
957 virtual void safepoint_synchronize_begin();
958 virtual void safepoint_synchronize_end();
959
960 // Does operations required after initialization has been done.
961 void post_initialize();
962
963 // Initialize weak reference processing.
964 void ref_processing_init();
965
966 virtual Name kind() const {
967 return CollectedHeap::G1;
968 }
969
970 virtual const char* name() const {
971 return "G1";
972 }
973
974 const G1CollectorState* collector_state() const { return &_collector_state; }
975 G1CollectorState* collector_state() { return &_collector_state; }
976
977 // The current policy object for the collector.
978 G1Policy* policy() const { return _policy; }
979 // The remembered set.
980 G1RemSet* rem_set() const { return _rem_set; }
981
982 inline G1GCPhaseTimes* phase_times() const;
983
984 HeapRegionManager* hrm() const { return _hrm; }
985
986 const G1CollectionSet* collection_set() const { return &_collection_set; }
987 G1CollectionSet* collection_set() { return &_collection_set; }
988
989 virtual SoftRefPolicy* soft_ref_policy();
990
991 virtual void initialize_serviceability();
992 virtual MemoryUsage memory_usage();
993 virtual GrowableArray<GCMemoryManager*> memory_managers();
994 virtual GrowableArray<MemoryPool*> memory_pools();
995
996 // Try to minimize the remembered set.
997 void scrub_rem_set();
998
999 // Apply the given closure on all cards in the Hot Card Cache, emptying it.
1000 void iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id);
1001
1002 // The shared block offset table array.
1003 G1BlockOffsetTable* bot() const { return _bot; }
1004
1005 // Reference Processing accessors
1006
1007 // The STW reference processor....
1008 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1009
1010 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; }
1011
1012 // The Concurrent Marking reference processor...
1013 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1014
1015 size_t unused_committed_regions_in_bytes() const;
1016
1017 virtual size_t capacity() const;
1018 virtual size_t used() const;
1019 // This should be called when we're not holding the heap lock. The
1020 // result might be a bit inaccurate.
1021 size_t used_unlocked() const;
1022 size_t recalculate_used() const;
1023
1024 // These virtual functions do the actual allocation.
1025 // Some heaps may offer a contiguous region for shared non-blocking
1026 // allocation, via inlined code (by exporting the address of the top and
1027 // end fields defining the extent of the contiguous allocation region.)
1028 // But G1CollectedHeap doesn't yet support this.
1029
1030 virtual bool is_maximal_no_gc() const {
1031 return _hrm->available() == 0;
1032 }
1033
1034 // Returns whether there are any regions left in the heap for allocation.
1035 bool has_regions_left_for_allocation() const {
1036 return !is_maximal_no_gc() || num_free_regions() != 0;
1037 }
1038
1039 // The current number of regions in the heap.
1040 uint num_regions() const { return _hrm->length(); }
1041
1042 // The max number of regions in the heap.
1043 uint max_regions() const { return _hrm->max_length(); }
1044
1045 // Max number of regions that can be comitted.
1046 uint max_expandable_regions() const { return _hrm->max_expandable_length(); }
1047
1048 // The number of regions that are completely free.
1049 uint num_free_regions() const { return _hrm->num_free_regions(); }
1050
1051 // The number of regions that can be allocated into.
1052 uint num_free_or_available_regions() const { return num_free_regions() + _hrm->available(); }
1053
1054 MemoryUsage get_auxiliary_data_memory_usage() const {
1055 return _hrm->get_auxiliary_data_memory_usage();
1056 }
1057
1058 // The number of regions that are not completely free.
1059 uint num_used_regions() const { return num_regions() - num_free_regions(); }
1060
1061 #ifdef ASSERT
1062 bool is_on_master_free_list(HeapRegion* hr) {
1063 return _hrm->is_free(hr);
1064 }
1065 #endif // ASSERT
1066
1067 inline void old_set_add(HeapRegion* hr);
1068 inline void old_set_remove(HeapRegion* hr);
1069
1070 inline void archive_set_add(HeapRegion* hr);
1071
1072 size_t non_young_capacity_bytes() {
1073 return (old_regions_count() + _archive_set.length() + humongous_regions_count()) * HeapRegion::GrainBytes;
1074 }
1075
1076 // Determine whether the given region is one that we are using as an
1077 // old GC alloc region.
1078 bool is_old_gc_alloc_region(HeapRegion* hr);
1079
1080 // Perform a collection of the heap; intended for use in implementing
1081 // "System.gc". This probably implies as full a collection as the
1082 // "CollectedHeap" supports.
1083 virtual void collect(GCCause::Cause cause);
1084
1085 // Perform a collection of the heap with the given cause.
1086 // Returns whether this collection actually executed.
1087 bool try_collect(GCCause::Cause cause);
1088
1089 // True iff an evacuation has failed in the most-recent collection.
1090 bool evacuation_failed() { return _evacuation_failed; }
1091
1092 void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed);
1093 void prepend_to_freelist(FreeRegionList* list);
1094 void decrement_summary_bytes(size_t bytes);
1095
1096 virtual bool is_in(const void* p) const;
1097 #ifdef ASSERT
1098 // Returns whether p is in one of the available areas of the heap. Slow but
1099 // extensive version.
1100 bool is_in_exact(const void* p) const;
1101 #endif
1102
1103 // Return "TRUE" iff the given object address is within the collection
1104 // set. Assumes that the reference points into the heap.
1105 inline bool is_in_cset(const HeapRegion *hr);
1106 inline bool is_in_cset(oop obj);
1107 inline bool is_in_cset(HeapWord* addr);
1108
1109 inline bool is_in_cset_or_humongous(const oop obj);
1110
1111 private:
1112 // This array is used for a quick test on whether a reference points into
1113 // the collection set or not. Each of the array's elements denotes whether the
1114 // corresponding region is in the collection set or not.
1115 G1HeapRegionAttrBiasedMappedArray _region_attr;
1116
1117 public:
1118
1119 inline G1HeapRegionAttr region_attr(const void* obj) const;
1120 inline G1HeapRegionAttr region_attr(uint idx) const;
1121
1122 // Return "TRUE" iff the given object address is in the reserved
1123 // region of g1.
1124 bool is_in_g1_reserved(const void* p) const {
1125 return _hrm->reserved().contains(p);
1126 }
1127
1128 // Returns a MemRegion that corresponds to the space that has been
1129 // reserved for the heap
1130 MemRegion g1_reserved() const {
1131 return _hrm->reserved();
1132 }
1133
1134 MemRegion reserved_region() const {
1135 return _reserved;
1136 }
1137
1138 HeapWord* base() const {
1139 return _reserved.start();
1140 }
1141
1142 bool is_in_reserved(const void* addr) const {
1143 return _reserved.contains(addr);
1144 }
1145
1146 G1HotCardCache* hot_card_cache() const { return _hot_card_cache; }
1147
1148 G1CardTable* card_table() const {
1149 return _card_table;
1150 }
1151
1152 // Iteration functions.
1153
1154 // Iterate over all objects, calling "cl.do_object" on each.
1155 virtual void object_iterate(ObjectClosure* cl);
1156
1157 virtual void safe_object_iterate(ObjectClosure* cl) {
1158 object_iterate(cl);
1159 }
1160
1161 // Iterate over heap regions, in address order, terminating the
1162 // iteration early if the "do_heap_region" method returns "true".
1163 void heap_region_iterate(HeapRegionClosure* blk) const;
1164
1165 // Return the region with the given index. It assumes the index is valid.
1166 inline HeapRegion* region_at(uint index) const;
1167 inline HeapRegion* region_at_or_null(uint index) const;
1168
1169 // Return the next region (by index) that is part of the same
1170 // humongous object that hr is part of.
1171 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const;
1172
1173 // Calculate the region index of the given address. Given address must be
1174 // within the heap.
1175 inline uint addr_to_region(HeapWord* addr) const;
1176
1177 inline HeapWord* bottom_addr_for_region(uint index) const;
1178
1179 // Two functions to iterate over the heap regions in parallel. Threads
1180 // compete using the HeapRegionClaimer to claim the regions before
1181 // applying the closure on them.
1182 // The _from_worker_offset version uses the HeapRegionClaimer and
1183 // the worker id to calculate a start offset to prevent all workers to
1184 // start from the point.
1185 void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
1186 HeapRegionClaimer* hrclaimer,
1187 uint worker_id) const;
1188
1189 void heap_region_par_iterate_from_start(HeapRegionClosure* cl,
1190 HeapRegionClaimer* hrclaimer) const;
1191
1192 // Iterate over all regions currently in the current collection set.
1193 void collection_set_iterate_all(HeapRegionClosure* blk);
1194
1195 // Iterate over the regions in the current increment of the collection set.
1196 // Starts the iteration so that the start regions of a given worker id over the
1197 // set active_workers are evenly spread across the set of collection set regions
1198 // to be iterated.
1199 // The variant with the HeapRegionClaimer guarantees that the closure will be
1200 // applied to a particular region exactly once.
1201 void collection_set_iterate_increment_from(HeapRegionClosure *blk, uint worker_id) {
1202 collection_set_iterate_increment_from(blk, NULL, worker_id);
1203 }
1204 void collection_set_iterate_increment_from(HeapRegionClosure *blk, HeapRegionClaimer* hr_claimer, uint worker_id);
1205
1206 // Returns the HeapRegion that contains addr. addr must not be NULL.
1207 template <class T>
1208 inline HeapRegion* heap_region_containing(const T addr) const;
1209
1210 // Returns the HeapRegion that contains addr, or NULL if that is an uncommitted
1211 // region. addr must not be NULL.
1212 template <class T>
1213 inline HeapRegion* heap_region_containing_or_null(const T addr) const;
1214
1215 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1216 // each address in the (reserved) heap is a member of exactly
1217 // one block. The defining characteristic of a block is that it is
1218 // possible to find its size, and thus to progress forward to the next
1219 // block. (Blocks may be of different sizes.) Thus, blocks may
1220 // represent Java objects, or they might be free blocks in a
1221 // free-list-based heap (or subheap), as long as the two kinds are
1222 // distinguishable and the size of each is determinable.
1223
1224 // Returns the address of the start of the "block" that contains the
1225 // address "addr". We say "blocks" instead of "object" since some heaps
1226 // may not pack objects densely; a chunk may either be an object or a
1227 // non-object.
1228 HeapWord* block_start(const void* addr) const;
1229
1230 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1231 // the block is an object.
1232 bool block_is_obj(const HeapWord* addr) const;
1233
1234 // Section on thread-local allocation buffers (TLABs)
1235 // See CollectedHeap for semantics.
1236
1237 bool supports_tlab_allocation() const;
1238 size_t tlab_capacity(Thread* ignored) const;
1239 size_t tlab_used(Thread* ignored) const;
1240 size_t max_tlab_size() const;
1241 size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1242
1243 inline bool is_in_young(const oop obj);
1244
1245 // Returns "true" iff the given word_size is "very large".
1246 static bool is_humongous(size_t word_size) {
1247 // Note this has to be strictly greater-than as the TLABs
1248 // are capped at the humongous threshold and we want to
1249 // ensure that we don't try to allocate a TLAB as
1250 // humongous and that we don't allocate a humongous
1251 // object in a TLAB.
1252 return word_size > _humongous_object_threshold_in_words;
1253 }
1254
1255 // Returns the humongous threshold for a specific region size
1256 static size_t humongous_threshold_for(size_t region_size) {
1257 return (region_size / 2);
1258 }
1259
1260 // Returns the number of regions the humongous object of the given word size
1261 // requires.
1262 static size_t humongous_obj_size_in_regions(size_t word_size);
1263
1264 // Print the maximum heap capacity.
1265 virtual size_t max_capacity() const;
1266
1267 // Return the size of reserved memory. Returns different value than max_capacity() when AllocateOldGenAt is used.
1268 virtual size_t max_reserved_capacity() const;
1269
1270 virtual jlong millis_since_last_gc();
1271
1272
1273 // Convenience function to be used in situations where the heap type can be
1274 // asserted to be this type.
1275 static G1CollectedHeap* heap();
1276
1277 void set_region_short_lived_locked(HeapRegion* hr);
1278 // add appropriate methods for any other surv rate groups
1279
1280 const G1SurvivorRegions* survivor() const { return &_survivor; }
1281
1282 uint eden_regions_count() const { return _eden.length(); }
1283 uint survivor_regions_count() const { return _survivor.length(); }
1284 size_t eden_regions_used_bytes() const { return _eden.used_bytes(); }
1285 size_t survivor_regions_used_bytes() const { return _survivor.used_bytes(); }
1286 uint young_regions_count() const { return _eden.length() + _survivor.length(); }
1287 uint old_regions_count() const { return _old_set.length(); }
1288 uint archive_regions_count() const { return _archive_set.length(); }
1289 uint humongous_regions_count() const { return _humongous_set.length(); }
1290
1291 #ifdef ASSERT
1292 bool check_young_list_empty();
1293 #endif
1294
1295 // *** Stuff related to concurrent marking. It's not clear to me that so
1296 // many of these need to be public.
1297
1298 // The functions below are helper functions that a subclass of
1299 // "CollectedHeap" can use in the implementation of its virtual
1300 // functions.
1301 // This performs a concurrent marking of the live objects in a
1302 // bitmap off to the side.
1303 void do_concurrent_mark();
1304
1305 bool is_marked_next(oop obj) const;
1306
1307 // Determine if an object is dead, given the object and also
1308 // the region to which the object belongs. An object is dead
1309 // iff a) it was not allocated since the last mark, b) it
1310 // is not marked, and c) it is not in an archive region.
1311 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1312 return
1313 hr->is_obj_dead(obj, _cm->prev_mark_bitmap()) &&
1314 !hr->is_archive();
1315 }
1316
1317 // This function returns true when an object has been
1318 // around since the previous marking and hasn't yet
1319 // been marked during this marking, and is not in an archive region.
1320 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1321 return
1322 !hr->obj_allocated_since_next_marking(obj) &&
1323 !is_marked_next(obj) &&
1324 !hr->is_archive();
1325 }
1326
1327 // Determine if an object is dead, given only the object itself.
1328 // This will find the region to which the object belongs and
1329 // then call the region version of the same function.
1330
1331 // Added if it is NULL it isn't dead.
1332
1333 inline bool is_obj_dead(const oop obj) const;
1334
1335 inline bool is_obj_ill(const oop obj) const;
1336
1337 inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const;
1338 inline bool is_obj_dead_full(const oop obj) const;
1339
1340 G1ConcurrentMark* concurrent_mark() const { return _cm; }
1341
1342 // Refinement
1343
1344 G1ConcurrentRefine* concurrent_refine() const { return _cr; }
1345
1346 // Optimized nmethod scanning support routines
1347
1348 // Register the given nmethod with the G1 heap.
1349 virtual void register_nmethod(nmethod* nm);
1350
1351 // Unregister the given nmethod from the G1 heap.
1352 virtual void unregister_nmethod(nmethod* nm);
1353
1354 // No nmethod flushing needed.
1355 virtual void flush_nmethod(nmethod* nm) {}
1356
1357 // No nmethod verification implemented.
1358 virtual void verify_nmethod(nmethod* nm) {}
1359
1360 // Free up superfluous code root memory.
1361 void purge_code_root_memory();
1362
1363 // Rebuild the strong code root lists for each region
1364 // after a full GC.
1365 void rebuild_strong_code_roots();
1366
1367 // Partial cleaning of VM internal data structures.
1368 void string_dedup_cleaning(BoolObjectClosure* is_alive,
1369 OopClosure* keep_alive,
1370 G1GCPhaseTimes* phase_times = NULL);
1371
1372 // Performs cleaning of data structures after class unloading.
1373 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred);
1374
1375 // Redirty logged cards in the refinement queue.
1376 void redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs);
1377
1378 // Verification
1379
1380 // Deduplicate the string
1381 virtual void deduplicate_string(oop str);
1382
1383 // Perform any cleanup actions necessary before allowing a verification.
1384 virtual void prepare_for_verify();
1385
1386 // Perform verification.
1387
1388 // vo == UsePrevMarking -> use "prev" marking information,
1389 // vo == UseNextMarking -> use "next" marking information
1390 // vo == UseFullMarking -> use "next" marking bitmap but no TAMS
1391 //
1392 // NOTE: Only the "prev" marking information is guaranteed to be
1393 // consistent most of the time, so most calls to this should use
1394 // vo == UsePrevMarking.
1395 // Currently, there is only one case where this is called with
1396 // vo == UseNextMarking, which is to verify the "next" marking
1397 // information at the end of remark.
1398 // Currently there is only one place where this is called with
1399 // vo == UseFullMarking, which is to verify the marking during a
1400 // full GC.
1401 void verify(VerifyOption vo);
1402
1403 // WhiteBox testing support.
1404 virtual bool supports_concurrent_phase_control() const;
1405 virtual bool request_concurrent_phase(const char* phase);
1406 bool is_heterogeneous_heap() const;
1407
1408 virtual WorkGang* get_safepoint_workers() { return _workers; }
1409
1410 // The methods below are here for convenience and dispatch the
1411 // appropriate method depending on value of the given VerifyOption
1412 // parameter. The values for that parameter, and their meanings,
1413 // are the same as those above.
1414
1415 bool is_obj_dead_cond(const oop obj,
1416 const HeapRegion* hr,
1417 const VerifyOption vo) const;
1418
1419 bool is_obj_dead_cond(const oop obj,
1420 const VerifyOption vo) const;
1421
1422 G1HeapSummary create_g1_heap_summary();
1423 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats);
1424
1425 // Printing
1426 private:
1427 void print_heap_regions() const;
1428 void print_regions_on(outputStream* st) const;
1429
1430 public:
1431 virtual void print_on(outputStream* st) const;
1432 virtual void print_extended_on(outputStream* st) const;
1433 virtual void print_on_error(outputStream* st) const;
1434
1435 virtual void print_gc_threads_on(outputStream* st) const;
1436 virtual void gc_threads_do(ThreadClosure* tc) const;
1437
1438 // Override
1439 void print_tracing_info() const;
1440
1441 // The following two methods are helpful for debugging RSet issues.
1442 void print_cset_rsets() PRODUCT_RETURN;
1443 void print_all_rsets() PRODUCT_RETURN;
1444
1445 // Used to print information about locations in the hs_err file.
1446 virtual bool print_location(outputStream* st, void* addr) const;
1447
1448 size_t pending_card_num();
1449 };
1450
1451 class G1ParEvacuateFollowersClosure : public VoidClosure {
1452 private:
1453 double _start_term;
1454 double _term_time;
1455 size_t _term_attempts;
1456
1457 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
1458 void end_term_time() { _term_time += (os::elapsedTime() - _start_term); }
1459 protected:
1460 G1CollectedHeap* _g1h;
1461 G1ParScanThreadState* _par_scan_state;
1462 RefToScanQueueSet* _queues;
1463 ParallelTaskTerminator* _terminator;
1464 G1GCPhaseTimes::GCParPhases _phase;
1465
1466 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
1467 RefToScanQueueSet* queues() { return _queues; }
1468 ParallelTaskTerminator* terminator() { return _terminator; }
1469
1470 public:
1471 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
1472 G1ParScanThreadState* par_scan_state,
1473 RefToScanQueueSet* queues,
1474 ParallelTaskTerminator* terminator,
1475 G1GCPhaseTimes::GCParPhases phase)
1476 : _start_term(0.0), _term_time(0.0), _term_attempts(0),
1477 _g1h(g1h), _par_scan_state(par_scan_state),
1478 _queues(queues), _terminator(terminator), _phase(phase) {}
1479
1480 void do_void();
1481
1482 double term_time() const { return _term_time; }
1483 size_t term_attempts() const { return _term_attempts; }
1484
1485 private:
1486 inline bool offer_termination();
1487 };
1488
1489 #endif // SHARE_GC_G1_G1COLLECTEDHEAP_HPP