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/g1NUMA.hpp"
45 #include "gc/g1/g1RedirtyCardsQueue.hpp"
46 #include "gc/g1/g1SurvivorRegions.hpp"
47 #include "gc/g1/g1YCTypes.hpp"
48 #include "gc/g1/heapRegionManager.hpp"
49 #include "gc/g1/heapRegionSet.hpp"
50 #include "gc/g1/heterogeneousHeapRegionManager.hpp"
51 #include "gc/shared/barrierSet.hpp"
52 #include "gc/shared/collectedHeap.hpp"
53 #include "gc/shared/gcHeapSummary.hpp"
54 #include "gc/shared/plab.hpp"
55 #include "gc/shared/preservedMarks.hpp"
56 #include "gc/shared/softRefPolicy.hpp"
57 #include "memory/memRegion.hpp"
58 #include "utilities/stack.hpp"
59
60 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
61 // It uses the "Garbage First" heap organization and algorithm, which
62 // may combine concurrent marking with parallel, incremental compaction of
63 // heap subsets that will yield large amounts of garbage.
64
65 // Forward declarations
66 class HeapRegion;
67 class GenerationSpec;
68 class G1ParScanThreadState;
69 class G1ParScanThreadStateSet;
70 class G1ParScanThreadState;
71 class MemoryPool;
72 class MemoryManager;
73 class ObjectClosure;
74 class SpaceClosure;
75 class CompactibleSpaceClosure;
76 class Space;
77 class G1CardTableEntryClosure;
78 class G1CollectionSet;
79 class G1Policy;
80 class G1HotCardCache;
81 class G1RemSet;
82 class G1YoungRemSetSamplingThread;
83 class G1ConcurrentMark;
84 class G1ConcurrentMarkThread;
85 class G1ConcurrentRefine;
86 class GenerationCounters;
87 class STWGCTimer;
88 class G1NewTracer;
89 class EvacuationFailedInfo;
90 class nmethod;
91 class WorkGang;
92 class G1Allocator;
93 class G1ArchiveAllocator;
94 class G1FullGCScope;
95 class G1HeapVerifier;
96 class G1HeapSizingPolicy;
97 class G1HeapSummary;
98 class G1EvacSummary;
99
100 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue;
101 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
102
103 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
104 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
105
106 // The G1 STW is alive closure.
107 // An instance is embedded into the G1CH and used as the
108 // (optional) _is_alive_non_header closure in the STW
109 // reference processor. It is also extensively used during
110 // reference processing during STW evacuation pauses.
111 class G1STWIsAliveClosure : public BoolObjectClosure {
112 G1CollectedHeap* _g1h;
113 public:
114 G1STWIsAliveClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
115 bool do_object_b(oop p);
116 };
117
118 class G1STWSubjectToDiscoveryClosure : public BoolObjectClosure {
119 G1CollectedHeap* _g1h;
120 public:
121 G1STWSubjectToDiscoveryClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
122 bool do_object_b(oop p);
123 };
124
125 class G1RegionMappingChangedListener : public G1MappingChangedListener {
126 private:
127 void reset_from_card_cache(uint start_idx, size_t num_regions);
128 public:
129 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
130 };
131
132 class G1CollectedHeap : public CollectedHeap {
133 friend class VM_CollectForMetadataAllocation;
134 friend class VM_G1CollectForAllocation;
135 friend class VM_G1CollectFull;
136 friend class VM_G1TryInitiateConcMark;
137 friend class VMStructs;
138 friend class MutatorAllocRegion;
139 friend class G1FullCollector;
140 friend class G1GCAllocRegion;
141 friend class G1HeapVerifier;
142
143 // Closures used in implementation.
144 friend class G1ParScanThreadState;
145 friend class G1ParScanThreadStateSet;
146 friend class G1EvacuateRegionsTask;
147 friend class G1PLABAllocator;
148
149 // Other related classes.
150 friend class HeapRegionClaimer;
151
152 // Testing classes.
153 friend class G1CheckRegionAttrTableClosure;
154
155 private:
156 G1YoungRemSetSamplingThread* _young_gen_sampling_thread;
157
158 WorkGang* _workers;
159 G1CardTable* _card_table;
160
161 SoftRefPolicy _soft_ref_policy;
162
163 static size_t _humongous_object_threshold_in_words;
164
165 // These sets keep track of old, archive and humongous regions respectively.
166 HeapRegionSet _old_set;
167 HeapRegionSet _archive_set;
168 HeapRegionSet _humongous_set;
169
170 void eagerly_reclaim_humongous_regions();
171 // Start a new incremental collection set for the next pause.
172 void start_new_collection_set();
173
174 // The block offset table for the G1 heap.
175 G1BlockOffsetTable* _bot;
176
177 // Tears down the region sets / lists so that they are empty and the
178 // regions on the heap do not belong to a region set / list. The
179 // only exception is the humongous set which we leave unaltered. If
180 // free_list_only is true, it will only tear down the master free
181 // list. It is called before a Full GC (free_list_only == false) or
182 // before heap shrinking (free_list_only == true).
183 void tear_down_region_sets(bool free_list_only);
184
185 // Rebuilds the region sets / lists so that they are repopulated to
186 // reflect the contents of the heap. The only exception is the
187 // humongous set which was not torn down in the first place. If
188 // free_list_only is true, it will only rebuild the master free
189 // list. It is called after a Full GC (free_list_only == false) or
190 // after heap shrinking (free_list_only == true).
191 void rebuild_region_sets(bool free_list_only);
192
193 // Callback for region mapping changed events.
194 G1RegionMappingChangedListener _listener;
195
196 // Handle G1 NUMA support.
197 G1NUMA* _numa;
198
199 // The sequence of all heap regions in the heap.
200 HeapRegionManager* _hrm;
201
202 // Manages all allocations with regions except humongous object allocations.
203 G1Allocator* _allocator;
204
205 // Manages all heap verification.
206 G1HeapVerifier* _verifier;
207
208 // Outside of GC pauses, the number of bytes used in all regions other
209 // than the current allocation region(s).
210 volatile size_t _summary_bytes_used;
211
212 void increase_used(size_t bytes);
213 void decrease_used(size_t bytes);
214
215 void set_used(size_t bytes);
216
217 // Class that handles archive allocation ranges.
218 G1ArchiveAllocator* _archive_allocator;
219
220 // GC allocation statistics policy for survivors.
221 G1EvacStats _survivor_evac_stats;
222
223 // GC allocation statistics policy for tenured objects.
224 G1EvacStats _old_evac_stats;
225
226 // It specifies whether we should attempt to expand the heap after a
227 // region allocation failure. If heap expansion fails we set this to
228 // false so that we don't re-attempt the heap expansion (it's likely
229 // that subsequent expansion attempts will also fail if one fails).
230 // Currently, it is only consulted during GC and it's reset at the
231 // start of each GC.
232 bool _expand_heap_after_alloc_failure;
233
234 // Helper for monitoring and management support.
235 G1MonitoringSupport* _g1mm;
236
237 // Records whether the region at the given index is (still) a
238 // candidate for eager reclaim. Only valid for humongous start
239 // regions; other regions have unspecified values. Humongous start
240 // regions are initialized at start of collection pause, with
241 // candidates removed from the set as they are found reachable from
242 // roots or the young generation.
243 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> {
244 protected:
245 bool default_value() const { return false; }
246 public:
247 void clear() { G1BiasedMappedArray<bool>::clear(); }
248 void set_candidate(uint region, bool value) {
249 set_by_index(region, value);
250 }
251 bool is_candidate(uint region) {
252 return get_by_index(region);
253 }
254 };
255
256 HumongousReclaimCandidates _humongous_reclaim_candidates;
257 // Stores whether during humongous object registration we found candidate regions.
258 // If not, we can skip a few steps.
259 bool _has_humongous_reclaim_candidates;
260
261 G1HRPrinter _hr_printer;
262
263 // Return true if an explicit GC should start a concurrent cycle instead
264 // of doing a STW full GC. A concurrent cycle should be started if:
265 // (a) cause == _g1_humongous_allocation,
266 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent,
267 // (c) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent,
268 // (d) cause == _wb_conc_mark,
269 // (e) cause == _g1_periodic_collection and +G1PeriodicGCInvokesConcurrent.
270 bool should_do_concurrent_full_gc(GCCause::Cause cause);
271
272 // Attempt to start a concurrent cycle with the indicated cause.
273 // precondition: should_do_concurrent_full_gc(cause)
274 bool try_collect_concurrently(GCCause::Cause cause,
275 uint gc_counter,
276 uint old_marking_started_before);
277
278 // Return true if should upgrade to full gc after an incremental one.
279 bool should_upgrade_to_full_gc(GCCause::Cause cause);
280
281 // indicates whether we are in young or mixed GC mode
282 G1CollectorState _collector_state;
283
284 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
285 // concurrent cycles) we have started.
286 volatile uint _old_marking_cycles_started;
287
288 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
289 // concurrent cycles) we have completed.
290 volatile uint _old_marking_cycles_completed;
291
292 // This is a non-product method that is helpful for testing. It is
293 // called at the end of a GC and artificially expands the heap by
294 // allocating a number of dead regions. This way we can induce very
295 // frequent marking cycles and stress the cleanup / concurrent
296 // cleanup code more (as all the regions that will be allocated by
297 // this method will be found dead by the marking cycle).
298 void allocate_dummy_regions() PRODUCT_RETURN;
299
300 // If the HR printer is active, dump the state of the regions in the
301 // heap after a compaction.
302 void print_hrm_post_compaction();
303
304 // Create a memory mapper for auxiliary data structures of the given size and
305 // translation factor.
306 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description,
307 size_t size,
308 size_t translation_factor);
309
310 void trace_heap(GCWhen::Type when, const GCTracer* tracer);
311
312 // These are macros so that, if the assert fires, we get the correct
313 // line number, file, etc.
314
315 #define heap_locking_asserts_params(_extra_message_) \
316 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
317 (_extra_message_), \
318 BOOL_TO_STR(Heap_lock->owned_by_self()), \
319 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
320 BOOL_TO_STR(Thread::current()->is_VM_thread())
321
322 #define assert_heap_locked() \
323 do { \
324 assert(Heap_lock->owned_by_self(), \
325 heap_locking_asserts_params("should be holding the Heap_lock")); \
326 } while (0)
327
328 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
329 do { \
330 assert(Heap_lock->owned_by_self() || \
331 (SafepointSynchronize::is_at_safepoint() && \
332 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
333 heap_locking_asserts_params("should be holding the Heap_lock or " \
334 "should be at a safepoint")); \
335 } while (0)
336
337 #define assert_heap_locked_and_not_at_safepoint() \
338 do { \
339 assert(Heap_lock->owned_by_self() && \
340 !SafepointSynchronize::is_at_safepoint(), \
341 heap_locking_asserts_params("should be holding the Heap_lock and " \
342 "should not be at a safepoint")); \
343 } while (0)
344
345 #define assert_heap_not_locked() \
346 do { \
347 assert(!Heap_lock->owned_by_self(), \
348 heap_locking_asserts_params("should not be holding the Heap_lock")); \
349 } while (0)
350
351 #define assert_heap_not_locked_and_not_at_safepoint() \
352 do { \
353 assert(!Heap_lock->owned_by_self() && \
354 !SafepointSynchronize::is_at_safepoint(), \
355 heap_locking_asserts_params("should not be holding the Heap_lock and " \
356 "should not be at a safepoint")); \
357 } while (0)
358
359 #define assert_at_safepoint_on_vm_thread() \
360 do { \
361 assert_at_safepoint(); \
362 assert(Thread::current_or_null() != NULL, "no current thread"); \
363 assert(Thread::current()->is_VM_thread(), "current thread is not VM thread"); \
364 } while (0)
365
366 #ifdef ASSERT
367 #define assert_used_and_recalculate_used_equal(g1h) \
368 do { \
369 size_t cur_used_bytes = g1h->used(); \
370 size_t recal_used_bytes = g1h->recalculate_used(); \
371 assert(cur_used_bytes == recal_used_bytes, "Used(" SIZE_FORMAT ") is not" \
372 " same as recalculated used(" SIZE_FORMAT ").", \
373 cur_used_bytes, recal_used_bytes); \
374 } while (0)
375 #else
376 #define assert_used_and_recalculate_used_equal(g1h) do {} while(0)
377 #endif
378
379 const char* young_gc_name() const;
380
381 // The young region list.
382 G1EdenRegions _eden;
383 G1SurvivorRegions _survivor;
384
385 STWGCTimer* _gc_timer_stw;
386
387 G1NewTracer* _gc_tracer_stw;
388
389 // The current policy object for the collector.
390 G1Policy* _policy;
391 G1HeapSizingPolicy* _heap_sizing_policy;
392
393 G1CollectionSet _collection_set;
394
395 // Try to allocate a single non-humongous HeapRegion sufficient for
396 // an allocation of the given word_size. If do_expand is true,
397 // attempt to expand the heap if necessary to satisfy the allocation
398 // request. 'type' takes the type of region to be allocated. (Use constants
399 // Old, Eden, Humongous, Survivor defined in HeapRegionType.)
400 HeapRegion* new_region(size_t word_size,
401 HeapRegionType type,
402 bool do_expand,
403 uint node_index = G1NUMA::AnyNodeIndex);
404
405 // Initialize a contiguous set of free regions of length num_regions
406 // and starting at index first so that they appear as a single
407 // humongous region.
408 HeapWord* humongous_obj_allocate_initialize_regions(uint first,
409 uint num_regions,
410 size_t word_size);
411
412 // Attempt to allocate a humongous object of the given size. Return
413 // NULL if unsuccessful.
414 HeapWord* humongous_obj_allocate(size_t word_size);
415
416 // The following two methods, allocate_new_tlab() and
417 // mem_allocate(), are the two main entry points from the runtime
418 // into the G1's allocation routines. They have the following
419 // assumptions:
420 //
421 // * They should both be called outside safepoints.
422 //
423 // * They should both be called without holding the Heap_lock.
424 //
425 // * All allocation requests for new TLABs should go to
426 // allocate_new_tlab().
427 //
428 // * All non-TLAB allocation requests should go to mem_allocate().
429 //
430 // * If either call cannot satisfy the allocation request using the
431 // current allocating region, they will try to get a new one. If
432 // this fails, they will attempt to do an evacuation pause and
433 // retry the allocation.
434 //
435 // * If all allocation attempts fail, even after trying to schedule
436 // an evacuation pause, allocate_new_tlab() will return NULL,
437 // whereas mem_allocate() will attempt a heap expansion and/or
438 // schedule a Full GC.
439 //
440 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
441 // should never be called with word_size being humongous. All
442 // humongous allocation requests should go to mem_allocate() which
443 // will satisfy them with a special path.
444
445 virtual HeapWord* allocate_new_tlab(size_t min_size,
446 size_t requested_size,
447 size_t* actual_size);
448
449 virtual HeapWord* mem_allocate(size_t word_size,
450 bool* gc_overhead_limit_was_exceeded);
451
452 // First-level mutator allocation attempt: try to allocate out of
453 // the mutator alloc region without taking the Heap_lock. This
454 // should only be used for non-humongous allocations.
455 inline HeapWord* attempt_allocation(size_t min_word_size,
456 size_t desired_word_size,
457 size_t* actual_word_size);
458
459 // Second-level mutator allocation attempt: take the Heap_lock and
460 // retry the allocation attempt, potentially scheduling a GC
461 // pause. This should only be used for non-humongous allocations.
462 HeapWord* attempt_allocation_slow(size_t word_size);
463
464 // Takes the Heap_lock and attempts a humongous allocation. It can
465 // potentially schedule a GC pause.
466 HeapWord* attempt_allocation_humongous(size_t word_size);
467
468 // Allocation attempt that should be called during safepoints (e.g.,
469 // at the end of a successful GC). expect_null_mutator_alloc_region
470 // specifies whether the mutator alloc region is expected to be NULL
471 // or not.
472 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
473 bool expect_null_mutator_alloc_region);
474
475 // These methods are the "callbacks" from the G1AllocRegion class.
476
477 // For mutator alloc regions.
478 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force, uint node_index);
479 void retire_mutator_alloc_region(HeapRegion* alloc_region,
480 size_t allocated_bytes);
481
482 // For GC alloc regions.
483 bool has_more_regions(G1HeapRegionAttr dest);
484 HeapRegion* new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index);
485 void retire_gc_alloc_region(HeapRegion* alloc_region,
486 size_t allocated_bytes, G1HeapRegionAttr dest);
487
488 // - if explicit_gc is true, the GC is for a System.gc() etc,
489 // otherwise it's for a failed allocation.
490 // - if clear_all_soft_refs is true, all soft references should be
491 // cleared during the GC.
492 // - it returns false if it is unable to do the collection due to the
493 // GC locker being active, true otherwise.
494 bool do_full_collection(bool explicit_gc,
495 bool clear_all_soft_refs);
496
497 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread.
498 virtual void do_full_collection(bool clear_all_soft_refs);
499
500 // Callback from VM_G1CollectForAllocation operation.
501 // This function does everything necessary/possible to satisfy a
502 // failed allocation request (including collection, expansion, etc.)
503 HeapWord* satisfy_failed_allocation(size_t word_size,
504 bool* succeeded);
505 // Internal helpers used during full GC to split it up to
506 // increase readability.
507 void abort_concurrent_cycle();
508 void verify_before_full_collection(bool explicit_gc);
509 void prepare_heap_for_full_collection();
510 void prepare_heap_for_mutators();
511 void abort_refinement();
512 void verify_after_full_collection();
513 void print_heap_after_full_collection(G1HeapTransition* heap_transition);
514
515 // Helper method for satisfy_failed_allocation()
516 HeapWord* satisfy_failed_allocation_helper(size_t word_size,
517 bool do_gc,
518 bool clear_all_soft_refs,
519 bool expect_null_mutator_alloc_region,
520 bool* gc_succeeded);
521
522 // Attempting to expand the heap sufficiently
523 // to support an allocation of the given "word_size". If
524 // successful, perform the allocation and return the address of the
525 // allocated block, or else "NULL".
526 HeapWord* expand_and_allocate(size_t word_size);
527
528 // Process any reference objects discovered.
529 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states);
530
531 // If during an initial mark pause we may install a pending list head which is not
532 // otherwise reachable ensure that it is marked in the bitmap for concurrent marking
533 // to discover.
534 void make_pending_list_reachable();
535
536 // Merges the information gathered on a per-thread basis for all worker threads
537 // during GC into global variables.
538 void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states);
539
540 void verify_numa_regions(const char* desc);
541
542 public:
543 G1YoungRemSetSamplingThread* sampling_thread() const { return _young_gen_sampling_thread; }
544
545 WorkGang* workers() const { return _workers; }
546
547 // Runs the given AbstractGangTask with the current active workers, returning the
548 // total time taken.
549 Tickspan run_task(AbstractGangTask* task);
550
551 G1Allocator* allocator() {
552 return _allocator;
553 }
554
555 G1HeapVerifier* verifier() {
556 return _verifier;
557 }
558
559 G1MonitoringSupport* g1mm() {
560 assert(_g1mm != NULL, "should have been initialized");
561 return _g1mm;
562 }
563
564 void resize_heap_if_necessary();
565
566 G1NUMA* numa() const { return _numa; }
567
568 // Expand the garbage-first heap by at least the given size (in bytes!).
569 // Returns true if the heap was expanded by the requested amount;
570 // false otherwise.
571 // (Rounds up to a HeapRegion boundary.)
572 bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL);
573 bool expand_single_region(uint node_index);
574
575 // Returns the PLAB statistics for a given destination.
576 inline G1EvacStats* alloc_buffer_stats(G1HeapRegionAttr dest);
577
578 // Determines PLAB size for a given destination.
579 inline size_t desired_plab_sz(G1HeapRegionAttr dest);
580
581 // Do anything common to GC's.
582 void gc_prologue(bool full);
583 void gc_epilogue(bool full);
584
585 // Does the given region fulfill remembered set based eager reclaim candidate requirements?
586 bool is_potential_eager_reclaim_candidate(HeapRegion* r) const;
587
588 // Modify the reclaim candidate set and test for presence.
589 // These are only valid for starts_humongous regions.
590 inline void set_humongous_reclaim_candidate(uint region, bool value);
591 inline bool is_humongous_reclaim_candidate(uint region);
592
593 // Remove from the reclaim candidate set. Also remove from the
594 // collection set so that later encounters avoid the slow path.
595 inline void set_humongous_is_live(oop obj);
596
597 // Register the given region to be part of the collection set.
598 inline void register_humongous_region_with_region_attr(uint index);
599 // Update region attributes table with information about all regions.
600 void register_regions_with_region_attr();
601 // We register a region with the fast "in collection set" test. We
602 // simply set to true the array slot corresponding to this region.
603 void register_young_region_with_region_attr(HeapRegion* r) {
604 _region_attr.set_in_young(r->hrm_index());
605 }
606 inline void register_region_with_region_attr(HeapRegion* r);
607 inline void register_old_region_with_region_attr(HeapRegion* r);
608 inline void register_optional_region_with_region_attr(HeapRegion* r);
609
610 void clear_region_attr(const HeapRegion* hr) {
611 _region_attr.clear(hr);
612 }
613
614 void clear_region_attr() {
615 _region_attr.clear();
616 }
617
618 // Verify that the G1RegionAttr remset tracking corresponds to actual remset tracking
619 // for all regions.
620 void verify_region_attr_remset_update() PRODUCT_RETURN;
621
622 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause);
623
624 // This is called at the start of either a concurrent cycle or a Full
625 // GC to update the number of old marking cycles started.
626 void increment_old_marking_cycles_started();
627
628 // This is called at the end of either a concurrent cycle or a Full
629 // GC to update the number of old marking cycles completed. Those two
630 // can happen in a nested fashion, i.e., we start a concurrent
631 // cycle, a Full GC happens half-way through it which ends first,
632 // and then the cycle notices that a Full GC happened and ends
633 // too. The concurrent parameter is a boolean to help us do a bit
634 // tighter consistency checking in the method. If concurrent is
635 // false, the caller is the inner caller in the nesting (i.e., the
636 // Full GC). If concurrent is true, the caller is the outer caller
637 // in this nesting (i.e., the concurrent cycle). Further nesting is
638 // not currently supported. The end of this call also notifies
639 // the G1OldGCCount_lock in case a Java thread is waiting for a full
640 // GC to happen (e.g., it called System.gc() with
641 // +ExplicitGCInvokesConcurrent).
642 void increment_old_marking_cycles_completed(bool concurrent);
643
644 uint old_marking_cycles_completed() {
645 return _old_marking_cycles_completed;
646 }
647
648 G1HRPrinter* hr_printer() { return &_hr_printer; }
649
650 // Allocates a new heap region instance.
651 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr);
652
653 // Allocate the highest free region in the reserved heap. This will commit
654 // regions as necessary.
655 HeapRegion* alloc_highest_free_region();
656
657 // Frees a non-humongous region by initializing its contents and
658 // adding it to the free list that's passed as a parameter (this is
659 // usually a local list which will be appended to the master free
660 // list later). The used bytes of freed regions are accumulated in
661 // pre_used. If skip_remset is true, the region's RSet will not be freed
662 // up. If skip_hot_card_cache is true, the region's hot card cache will not
663 // be freed up. The assumption is that this will be done later.
664 // The locked parameter indicates if the caller has already taken
665 // care of proper synchronization. This may allow some optimizations.
666 void free_region(HeapRegion* hr,
667 FreeRegionList* free_list,
668 bool skip_remset,
669 bool skip_hot_card_cache = false,
670 bool locked = false);
671
672 // It dirties the cards that cover the block so that the post
673 // write barrier never queues anything when updating objects on this
674 // block. It is assumed (and in fact we assert) that the block
675 // belongs to a young region.
676 inline void dirty_young_block(HeapWord* start, size_t word_size);
677
678 // Frees a humongous region by collapsing it into individual regions
679 // and calling free_region() for each of them. The freed regions
680 // will be added to the free list that's passed as a parameter (this
681 // is usually a local list which will be appended to the master free
682 // list later).
683 // The method assumes that only a single thread is ever calling
684 // this for a particular region at once.
685 void free_humongous_region(HeapRegion* hr,
686 FreeRegionList* free_list);
687
688 // Facility for allocating in 'archive' regions in high heap memory and
689 // recording the allocated ranges. These should all be called from the
690 // VM thread at safepoints, without the heap lock held. They can be used
691 // to create and archive a set of heap regions which can be mapped at the
692 // same fixed addresses in a subsequent JVM invocation.
693 void begin_archive_alloc_range(bool open = false);
694
695 // Check if the requested size would be too large for an archive allocation.
696 bool is_archive_alloc_too_large(size_t word_size);
697
698 // Allocate memory of the requested size from the archive region. This will
699 // return NULL if the size is too large or if no memory is available. It
700 // does not trigger a garbage collection.
701 HeapWord* archive_mem_allocate(size_t word_size);
702
703 // Optionally aligns the end address and returns the allocated ranges in
704 // an array of MemRegions in order of ascending addresses.
705 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
706 size_t end_alignment_in_bytes = 0);
707
708 // Facility for allocating a fixed range within the heap and marking
709 // the containing regions as 'archive'. For use at JVM init time, when the
710 // caller may mmap archived heap data at the specified range(s).
711 // Verify that the MemRegions specified in the argument array are within the
712 // reserved heap.
713 bool check_archive_addresses(MemRegion* range, size_t count);
714
715 // Commit the appropriate G1 regions containing the specified MemRegions
716 // and mark them as 'archive' regions. The regions in the array must be
717 // non-overlapping and in order of ascending address.
718 bool alloc_archive_regions(MemRegion* range, size_t count, bool open);
719
720 // Insert any required filler objects in the G1 regions around the specified
721 // ranges to make the regions parseable. This must be called after
722 // alloc_archive_regions, and after class loading has occurred.
723 void fill_archive_regions(MemRegion* range, size_t count);
724
725 // For each of the specified MemRegions, uncommit the containing G1 regions
726 // which had been allocated by alloc_archive_regions. This should be called
727 // rather than fill_archive_regions at JVM init time if the archive file
728 // mapping failed, with the same non-overlapping and sorted MemRegion array.
729 void dealloc_archive_regions(MemRegion* range, size_t count, bool is_open);
730
731 oop materialize_archived_object(oop obj);
732
733 private:
734
735 // Shrink the garbage-first heap by at most the given size (in bytes!).
736 // (Rounds down to a HeapRegion boundary.)
737 void shrink(size_t expand_bytes);
738 void shrink_helper(size_t expand_bytes);
739
740 #if TASKQUEUE_STATS
741 static void print_taskqueue_stats_hdr(outputStream* const st);
742 void print_taskqueue_stats() const;
743 void reset_taskqueue_stats();
744 #endif // TASKQUEUE_STATS
745
746 // Schedule the VM operation that will do an evacuation pause to
747 // satisfy an allocation request of word_size. *succeeded will
748 // return whether the VM operation was successful (it did do an
749 // evacuation pause) or not (another thread beat us to it or the GC
750 // locker was active). Given that we should not be holding the
751 // Heap_lock when we enter this method, we will pass the
752 // gc_count_before (i.e., total_collections()) as a parameter since
753 // it has to be read while holding the Heap_lock. Currently, both
754 // methods that call do_collection_pause() release the Heap_lock
755 // before the call, so it's easy to read gc_count_before just before.
756 HeapWord* do_collection_pause(size_t word_size,
757 uint gc_count_before,
758 bool* succeeded,
759 GCCause::Cause gc_cause);
760
761 void wait_for_root_region_scanning();
762
763 // The guts of the incremental collection pause, executed by the vm
764 // thread. It returns false if it is unable to do the collection due
765 // to the GC locker being active, true otherwise
766 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
767
768 G1HeapVerifier::G1VerifyType young_collection_verify_type() const;
769 void verify_before_young_collection(G1HeapVerifier::G1VerifyType type);
770 void verify_after_young_collection(G1HeapVerifier::G1VerifyType type);
771
772 void calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms);
773
774 // Actually do the work of evacuating the parts of the collection set.
775 void evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states);
776 void evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states);
777 private:
778 // Evacuate the next set of optional regions.
779 void evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states);
780
781 public:
782 void pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss);
783 void post_evacuate_collection_set(G1EvacuationInfo& evacuation_info,
784 G1RedirtyCardsQueueSet* rdcqs,
785 G1ParScanThreadStateSet* pss);
786
787 void expand_heap_after_young_collection();
788 // Update object copying statistics.
789 void record_obj_copy_mem_stats();
790
791 // The hot card cache for remembered set insertion optimization.
792 G1HotCardCache* _hot_card_cache;
793
794 // The g1 remembered set of the heap.
795 G1RemSet* _rem_set;
796
797 // After a collection pause, convert the regions in the collection set into free
798 // regions.
799 void free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words);
800
801 // Abandon the current collection set without recording policy
802 // statistics or updating free lists.
803 void abandon_collection_set(G1CollectionSet* collection_set);
804
805 // The concurrent marker (and the thread it runs in.)
806 G1ConcurrentMark* _cm;
807 G1ConcurrentMarkThread* _cm_thread;
808
809 // The concurrent refiner.
810 G1ConcurrentRefine* _cr;
811
812 // The parallel task queues
813 RefToScanQueueSet *_task_queues;
814
815 // True iff a evacuation has failed in the current collection.
816 bool _evacuation_failed;
817
818 EvacuationFailedInfo* _evacuation_failed_info_array;
819
820 // Failed evacuations cause some logical from-space objects to have
821 // forwarding pointers to themselves. Reset them.
822 void remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs);
823
824 // Restore the objects in the regions in the collection set after an
825 // evacuation failure.
826 void restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs);
827
828 PreservedMarksSet _preserved_marks_set;
829
830 // Preserve the mark of "obj", if necessary, in preparation for its mark
831 // word being overwritten with a self-forwarding-pointer.
832 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m);
833
834 #ifndef PRODUCT
835 // Support for forcing evacuation failures. Analogous to
836 // PromotionFailureALot for the other collectors.
837
838 // Records whether G1EvacuationFailureALot should be in effect
839 // for the current GC
840 bool _evacuation_failure_alot_for_current_gc;
841
842 // Used to record the GC number for interval checking when
843 // determining whether G1EvaucationFailureALot is in effect
844 // for the current GC.
845 size_t _evacuation_failure_alot_gc_number;
846
847 // Count of the number of evacuations between failures.
848 volatile size_t _evacuation_failure_alot_count;
849
850 // Set whether G1EvacuationFailureALot should be in effect
851 // for the current GC (based upon the type of GC and which
852 // command line flags are set);
853 inline bool evacuation_failure_alot_for_gc_type(bool for_young_gc,
854 bool during_initial_mark,
855 bool mark_or_rebuild_in_progress);
856
857 inline void set_evacuation_failure_alot_for_current_gc();
858
859 // Return true if it's time to cause an evacuation failure.
860 inline bool evacuation_should_fail();
861
862 // Reset the G1EvacuationFailureALot counters. Should be called at
863 // the end of an evacuation pause in which an evacuation failure occurred.
864 inline void reset_evacuation_should_fail();
865 #endif // !PRODUCT
866
867 // ("Weak") Reference processing support.
868 //
869 // G1 has 2 instances of the reference processor class. One
870 // (_ref_processor_cm) handles reference object discovery
871 // and subsequent processing during concurrent marking cycles.
872 //
873 // The other (_ref_processor_stw) handles reference object
874 // discovery and processing during full GCs and incremental
875 // evacuation pauses.
876 //
877 // During an incremental pause, reference discovery will be
878 // temporarily disabled for _ref_processor_cm and will be
879 // enabled for _ref_processor_stw. At the end of the evacuation
880 // pause references discovered by _ref_processor_stw will be
881 // processed and discovery will be disabled. The previous
882 // setting for reference object discovery for _ref_processor_cm
883 // will be re-instated.
884 //
885 // At the start of marking:
886 // * Discovery by the CM ref processor is verified to be inactive
887 // and it's discovered lists are empty.
888 // * Discovery by the CM ref processor is then enabled.
889 //
890 // At the end of marking:
891 // * Any references on the CM ref processor's discovered
892 // lists are processed (possibly MT).
893 //
894 // At the start of full GC we:
895 // * Disable discovery by the CM ref processor and
896 // empty CM ref processor's discovered lists
897 // (without processing any entries).
898 // * Verify that the STW ref processor is inactive and it's
899 // discovered lists are empty.
900 // * Temporarily set STW ref processor discovery as single threaded.
901 // * Temporarily clear the STW ref processor's _is_alive_non_header
902 // field.
903 // * Finally enable discovery by the STW ref processor.
904 //
905 // The STW ref processor is used to record any discovered
906 // references during the full GC.
907 //
908 // At the end of a full GC we:
909 // * Enqueue any reference objects discovered by the STW ref processor
910 // that have non-live referents. This has the side-effect of
911 // making the STW ref processor inactive by disabling discovery.
912 // * Verify that the CM ref processor is still inactive
913 // and no references have been placed on it's discovered
914 // lists (also checked as a precondition during initial marking).
915
916 // The (stw) reference processor...
917 ReferenceProcessor* _ref_processor_stw;
918
919 // During reference object discovery, the _is_alive_non_header
920 // closure (if non-null) is applied to the referent object to
921 // determine whether the referent is live. If so then the
922 // reference object does not need to be 'discovered' and can
923 // be treated as a regular oop. This has the benefit of reducing
924 // the number of 'discovered' reference objects that need to
925 // be processed.
926 //
927 // Instance of the is_alive closure for embedding into the
928 // STW reference processor as the _is_alive_non_header field.
929 // Supplying a value for the _is_alive_non_header field is
930 // optional but doing so prevents unnecessary additions to
931 // the discovered lists during reference discovery.
932 G1STWIsAliveClosure _is_alive_closure_stw;
933
934 G1STWSubjectToDiscoveryClosure _is_subject_to_discovery_stw;
935
936 // The (concurrent marking) reference processor...
937 ReferenceProcessor* _ref_processor_cm;
938
939 // Instance of the concurrent mark is_alive closure for embedding
940 // into the Concurrent Marking reference processor as the
941 // _is_alive_non_header field. Supplying a value for the
942 // _is_alive_non_header field is optional but doing so prevents
943 // unnecessary additions to the discovered lists during reference
944 // discovery.
945 G1CMIsAliveClosure _is_alive_closure_cm;
946
947 G1CMSubjectToDiscoveryClosure _is_subject_to_discovery_cm;
948 public:
949
950 RefToScanQueue *task_queue(uint i) const;
951
952 uint num_task_queues() const;
953
954 // Create a G1CollectedHeap.
955 // Must call the initialize method afterwards.
956 // May not return if something goes wrong.
957 G1CollectedHeap();
958
959 private:
960 jint initialize_concurrent_refinement();
961 jint initialize_young_gen_sampling_thread();
962 public:
963 // Initialize the G1CollectedHeap to have the initial and
964 // maximum sizes and remembered and barrier sets
965 // specified by the policy object.
966 jint initialize();
967
968 virtual void stop();
969 virtual void safepoint_synchronize_begin();
970 virtual void safepoint_synchronize_end();
971
972 // Does operations required after initialization has been done.
973 void post_initialize();
974
975 // Initialize weak reference processing.
976 void ref_processing_init();
977
978 virtual Name kind() const {
979 return CollectedHeap::G1;
980 }
981
982 virtual const char* name() const {
983 return "G1";
984 }
985
986 const G1CollectorState* collector_state() const { return &_collector_state; }
987 G1CollectorState* collector_state() { return &_collector_state; }
988
989 // The current policy object for the collector.
990 G1Policy* policy() const { return _policy; }
991 // The remembered set.
992 G1RemSet* rem_set() const { return _rem_set; }
993
994 inline G1GCPhaseTimes* phase_times() const;
995
996 HeapRegionManager* hrm() const { return _hrm; }
997
998 const G1CollectionSet* collection_set() const { return &_collection_set; }
999 G1CollectionSet* collection_set() { return &_collection_set; }
1000
1001 virtual SoftRefPolicy* soft_ref_policy();
1002
1003 virtual void initialize_serviceability();
1004 virtual MemoryUsage memory_usage();
1005 virtual GrowableArray<GCMemoryManager*> memory_managers();
1006 virtual GrowableArray<MemoryPool*> memory_pools();
1007
1008 // Try to minimize the remembered set.
1009 void scrub_rem_set();
1010
1011 // Apply the given closure on all cards in the Hot Card Cache, emptying it.
1012 void iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id);
1013
1014 // The shared block offset table array.
1015 G1BlockOffsetTable* bot() const { return _bot; }
1016
1017 // Reference Processing accessors
1018
1019 // The STW reference processor....
1020 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1021
1022 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; }
1023
1024 // The Concurrent Marking reference processor...
1025 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1026
1027 size_t unused_committed_regions_in_bytes() const;
1028
1029 virtual size_t capacity() const;
1030 virtual size_t used() const;
1031 // This should be called when we're not holding the heap lock. The
1032 // result might be a bit inaccurate.
1033 size_t used_unlocked() const;
1034 size_t recalculate_used() const;
1035
1036 // These virtual functions do the actual allocation.
1037 // Some heaps may offer a contiguous region for shared non-blocking
1038 // allocation, via inlined code (by exporting the address of the top and
1039 // end fields defining the extent of the contiguous allocation region.)
1040 // But G1CollectedHeap doesn't yet support this.
1041
1042 virtual bool is_maximal_no_gc() const {
1043 return _hrm->available() == 0;
1044 }
1045
1046 // Returns whether there are any regions left in the heap for allocation.
1047 bool has_regions_left_for_allocation() const {
1048 return !is_maximal_no_gc() || num_free_regions() != 0;
1049 }
1050
1051 // The current number of regions in the heap.
1052 uint num_regions() const { return _hrm->length(); }
1053
1054 // The max number of regions in the heap.
1055 uint max_regions() const { return _hrm->max_length(); }
1056
1057 // Max number of regions that can be comitted.
1058 uint max_expandable_regions() const { return _hrm->max_expandable_length(); }
1059
1060 // The number of regions that are completely free.
1061 uint num_free_regions() const { return _hrm->num_free_regions(); }
1062
1063 // The number of regions that can be allocated into.
1064 uint num_free_or_available_regions() const { return num_free_regions() + _hrm->available(); }
1065
1066 MemoryUsage get_auxiliary_data_memory_usage() const {
1067 return _hrm->get_auxiliary_data_memory_usage();
1068 }
1069
1070 // The number of regions that are not completely free.
1071 uint num_used_regions() const { return num_regions() - num_free_regions(); }
1072
1073 #ifdef ASSERT
1074 bool is_on_master_free_list(HeapRegion* hr) {
1075 return _hrm->is_free(hr);
1076 }
1077 #endif // ASSERT
1078
1079 inline void old_set_add(HeapRegion* hr);
1080 inline void old_set_remove(HeapRegion* hr);
1081
1082 inline void archive_set_add(HeapRegion* hr);
1083
1084 size_t non_young_capacity_bytes() {
1085 return (old_regions_count() + _archive_set.length() + humongous_regions_count()) * HeapRegion::GrainBytes;
1086 }
1087
1088 // Determine whether the given region is one that we are using as an
1089 // old GC alloc region.
1090 bool is_old_gc_alloc_region(HeapRegion* hr);
1091
1092 // Perform a collection of the heap; intended for use in implementing
1093 // "System.gc". This probably implies as full a collection as the
1094 // "CollectedHeap" supports.
1095 virtual void collect(GCCause::Cause cause);
1096
1097 // Perform a collection of the heap with the given cause.
1098 // Returns whether this collection actually executed.
1099 bool try_collect(GCCause::Cause cause);
1100
1101 // True iff an evacuation has failed in the most-recent collection.
1102 bool evacuation_failed() { return _evacuation_failed; }
1103
1104 void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed);
1105 void prepend_to_freelist(FreeRegionList* list);
1106 void decrement_summary_bytes(size_t bytes);
1107
1108 virtual bool is_in(const void* p) const;
1109 #ifdef ASSERT
1110 // Returns whether p is in one of the available areas of the heap. Slow but
1111 // extensive version.
1112 bool is_in_exact(const void* p) const;
1113 #endif
1114
1115 // Return "TRUE" iff the given object address is within the collection
1116 // set. Assumes that the reference points into the heap.
1117 inline bool is_in_cset(const HeapRegion *hr);
1118 inline bool is_in_cset(oop obj);
1119 inline bool is_in_cset(HeapWord* addr);
1120
1121 inline bool is_in_cset_or_humongous(const oop obj);
1122
1123 private:
1124 // This array is used for a quick test on whether a reference points into
1125 // the collection set or not. Each of the array's elements denotes whether the
1126 // corresponding region is in the collection set or not.
1127 G1HeapRegionAttrBiasedMappedArray _region_attr;
1128
1129 public:
1130
1131 inline G1HeapRegionAttr region_attr(const void* obj) const;
1132 inline G1HeapRegionAttr region_attr(uint idx) const;
1133
1134 // Return "TRUE" iff the given object address is in the reserved
1135 // region of g1.
1136 bool is_in_g1_reserved(const void* p) const {
1137 return _hrm->reserved().contains(p);
1138 }
1139
1140 // Returns a MemRegion that corresponds to the space that has been
1141 // reserved for the heap
1142 MemRegion g1_reserved() const {
1143 return _hrm->reserved();
1144 }
1145
1146 MemRegion reserved_region() const {
1147 return _reserved;
1148 }
1149
1150 HeapWord* base() const {
1151 return _reserved.start();
1152 }
1153
1154 bool is_in_reserved(const void* addr) const {
1155 return _reserved.contains(addr);
1156 }
1157
1158 G1HotCardCache* hot_card_cache() const { return _hot_card_cache; }
1159
1160 G1CardTable* card_table() const {
1161 return _card_table;
1162 }
1163
1164 // Iteration functions.
1165
1166 // Iterate over all objects, calling "cl.do_object" on each.
1167 virtual void object_iterate(ObjectClosure* cl);
1168
1169 // Iterate over heap regions, in address order, terminating the
1170 // iteration early if the "do_heap_region" method returns "true".
1171 void heap_region_iterate(HeapRegionClosure* blk) const;
1172
1173 // Return the region with the given index. It assumes the index is valid.
1174 inline HeapRegion* region_at(uint index) const;
1175 inline HeapRegion* region_at_or_null(uint index) const;
1176
1177 // Return the next region (by index) that is part of the same
1178 // humongous object that hr is part of.
1179 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const;
1180
1181 // Calculate the region index of the given address. Given address must be
1182 // within the heap.
1183 inline uint addr_to_region(HeapWord* addr) const;
1184
1185 inline HeapWord* bottom_addr_for_region(uint index) const;
1186
1187 // Two functions to iterate over the heap regions in parallel. Threads
1188 // compete using the HeapRegionClaimer to claim the regions before
1189 // applying the closure on them.
1190 // The _from_worker_offset version uses the HeapRegionClaimer and
1191 // the worker id to calculate a start offset to prevent all workers to
1192 // start from the point.
1193 void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
1194 HeapRegionClaimer* hrclaimer,
1195 uint worker_id) const;
1196
1197 void heap_region_par_iterate_from_start(HeapRegionClosure* cl,
1198 HeapRegionClaimer* hrclaimer) const;
1199
1200 // Iterate over all regions currently in the current collection set.
1201 void collection_set_iterate_all(HeapRegionClosure* blk);
1202
1203 // Iterate over the regions in the current increment of the collection set.
1204 // Starts the iteration so that the start regions of a given worker id over the
1205 // set active_workers are evenly spread across the set of collection set regions
1206 // to be iterated.
1207 // The variant with the HeapRegionClaimer guarantees that the closure will be
1208 // applied to a particular region exactly once.
1209 void collection_set_iterate_increment_from(HeapRegionClosure *blk, uint worker_id) {
1210 collection_set_iterate_increment_from(blk, NULL, worker_id);
1211 }
1212 void collection_set_iterate_increment_from(HeapRegionClosure *blk, HeapRegionClaimer* hr_claimer, uint worker_id);
1213
1214 // Returns the HeapRegion that contains addr. addr must not be NULL.
1215 template <class T>
1216 inline HeapRegion* heap_region_containing(const T addr) const;
1217
1218 // Returns the HeapRegion that contains addr, or NULL if that is an uncommitted
1219 // region. addr must not be NULL.
1220 template <class T>
1221 inline HeapRegion* heap_region_containing_or_null(const T addr) const;
1222
1223 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1224 // each address in the (reserved) heap is a member of exactly
1225 // one block. The defining characteristic of a block is that it is
1226 // possible to find its size, and thus to progress forward to the next
1227 // block. (Blocks may be of different sizes.) Thus, blocks may
1228 // represent Java objects, or they might be free blocks in a
1229 // free-list-based heap (or subheap), as long as the two kinds are
1230 // distinguishable and the size of each is determinable.
1231
1232 // Returns the address of the start of the "block" that contains the
1233 // address "addr". We say "blocks" instead of "object" since some heaps
1234 // may not pack objects densely; a chunk may either be an object or a
1235 // non-object.
1236 HeapWord* block_start(const void* addr) const;
1237
1238 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1239 // the block is an object.
1240 bool block_is_obj(const HeapWord* addr) const;
1241
1242 // Section on thread-local allocation buffers (TLABs)
1243 // See CollectedHeap for semantics.
1244
1245 bool supports_tlab_allocation() const;
1246 size_t tlab_capacity(Thread* ignored) const;
1247 size_t tlab_used(Thread* ignored) const;
1248 size_t max_tlab_size() const;
1249 size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1250
1251 inline bool is_in_young(const oop obj);
1252
1253 // Returns "true" iff the given word_size is "very large".
1254 static bool is_humongous(size_t word_size) {
1255 // Note this has to be strictly greater-than as the TLABs
1256 // are capped at the humongous threshold and we want to
1257 // ensure that we don't try to allocate a TLAB as
1258 // humongous and that we don't allocate a humongous
1259 // object in a TLAB.
1260 return word_size > _humongous_object_threshold_in_words;
1261 }
1262
1263 // Returns the humongous threshold for a specific region size
1264 static size_t humongous_threshold_for(size_t region_size) {
1265 return (region_size / 2);
1266 }
1267
1268 // Returns the number of regions the humongous object of the given word size
1269 // requires.
1270 static size_t humongous_obj_size_in_regions(size_t word_size);
1271
1272 // Print the maximum heap capacity.
1273 virtual size_t max_capacity() const;
1274
1275 // Return the size of reserved memory. Returns different value than max_capacity() when AllocateOldGenAt is used.
1276 virtual size_t max_reserved_capacity() const;
1277
1278 virtual jlong millis_since_last_gc();
1279
1280
1281 // Convenience function to be used in situations where the heap type can be
1282 // asserted to be this type.
1283 static G1CollectedHeap* heap();
1284
1285 void set_region_short_lived_locked(HeapRegion* hr);
1286 // add appropriate methods for any other surv rate groups
1287
1288 const G1SurvivorRegions* survivor() const { return &_survivor; }
1289
1290 uint eden_regions_count() const { return _eden.length(); }
1291 uint eden_regions_count(uint node_index) const { return _eden.regions_on_node(node_index); }
1292 uint survivor_regions_count() const { return _survivor.length(); }
1293 uint survivor_regions_count(uint node_index) const { return _survivor.regions_on_node(node_index); }
1294 size_t eden_regions_used_bytes() const { return _eden.used_bytes(); }
1295 size_t survivor_regions_used_bytes() const { return _survivor.used_bytes(); }
1296 uint young_regions_count() const { return _eden.length() + _survivor.length(); }
1297 uint old_regions_count() const { return _old_set.length(); }
1298 uint archive_regions_count() const { return _archive_set.length(); }
1299 uint humongous_regions_count() const { return _humongous_set.length(); }
1300
1301 #ifdef ASSERT
1302 bool check_young_list_empty();
1303 #endif
1304
1305 // *** Stuff related to concurrent marking. It's not clear to me that so
1306 // many of these need to be public.
1307
1308 // The functions below are helper functions that a subclass of
1309 // "CollectedHeap" can use in the implementation of its virtual
1310 // functions.
1311 // This performs a concurrent marking of the live objects in a
1312 // bitmap off to the side.
1313 void do_concurrent_mark();
1314
1315 bool is_marked_next(oop obj) const;
1316
1317 // Determine if an object is dead, given the object and also
1318 // the region to which the object belongs. An object is dead
1319 // iff a) it was not allocated since the last mark, b) it
1320 // is not marked, and c) it is not in an archive region.
1321 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1322 return
1323 hr->is_obj_dead(obj, _cm->prev_mark_bitmap()) &&
1324 !hr->is_archive();
1325 }
1326
1327 // This function returns true when an object has been
1328 // around since the previous marking and hasn't yet
1329 // been marked during this marking, and is not in an archive region.
1330 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1331 return
1332 !hr->obj_allocated_since_next_marking(obj) &&
1333 !is_marked_next(obj) &&
1334 !hr->is_archive();
1335 }
1336
1337 // Determine if an object is dead, given only the object itself.
1338 // This will find the region to which the object belongs and
1339 // then call the region version of the same function.
1340
1341 // Added if it is NULL it isn't dead.
1342
1343 inline bool is_obj_dead(const oop obj) const;
1344
1345 inline bool is_obj_ill(const oop obj) const;
1346
1347 inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const;
1348 inline bool is_obj_dead_full(const oop obj) const;
1349
1350 G1ConcurrentMark* concurrent_mark() const { return _cm; }
1351
1352 // Refinement
1353
1354 G1ConcurrentRefine* concurrent_refine() const { return _cr; }
1355
1356 // Optimized nmethod scanning support routines
1357
1358 // Register the given nmethod with the G1 heap.
1359 virtual void register_nmethod(nmethod* nm);
1360
1361 // Unregister the given nmethod from the G1 heap.
1362 virtual void unregister_nmethod(nmethod* nm);
1363
1364 // No nmethod flushing needed.
1365 virtual void flush_nmethod(nmethod* nm) {}
1366
1367 // No nmethod verification implemented.
1368 virtual void verify_nmethod(nmethod* nm) {}
1369
1370 // Free up superfluous code root memory.
1371 void purge_code_root_memory();
1372
1373 // Rebuild the strong code root lists for each region
1374 // after a full GC.
1375 void rebuild_strong_code_roots();
1376
1377 // Partial cleaning of VM internal data structures.
1378 void string_dedup_cleaning(BoolObjectClosure* is_alive,
1379 OopClosure* keep_alive,
1380 G1GCPhaseTimes* phase_times = NULL);
1381
1382 // Performs cleaning of data structures after class unloading.
1383 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred);
1384
1385 // Redirty logged cards in the refinement queue.
1386 void redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs);
1387
1388 // Verification
1389
1390 // Deduplicate the string
1391 virtual void deduplicate_string(oop str);
1392
1393 // Perform any cleanup actions necessary before allowing a verification.
1394 virtual void prepare_for_verify();
1395
1396 // Perform verification.
1397
1398 // vo == UsePrevMarking -> use "prev" marking information,
1399 // vo == UseNextMarking -> use "next" marking information
1400 // vo == UseFullMarking -> use "next" marking bitmap but no TAMS
1401 //
1402 // NOTE: Only the "prev" marking information is guaranteed to be
1403 // consistent most of the time, so most calls to this should use
1404 // vo == UsePrevMarking.
1405 // Currently, there is only one case where this is called with
1406 // vo == UseNextMarking, which is to verify the "next" marking
1407 // information at the end of remark.
1408 // Currently there is only one place where this is called with
1409 // vo == UseFullMarking, which is to verify the marking during a
1410 // full GC.
1411 void verify(VerifyOption vo);
1412
1413 // WhiteBox testing support.
1414 virtual bool supports_concurrent_phase_control() const;
1415 virtual bool request_concurrent_phase(const char* phase);
1416 bool is_heterogeneous_heap() const;
1417
1418 virtual WorkGang* get_safepoint_workers() { return _workers; }
1419
1420 // The methods below are here for convenience and dispatch the
1421 // appropriate method depending on value of the given VerifyOption
1422 // parameter. The values for that parameter, and their meanings,
1423 // are the same as those above.
1424
1425 bool is_obj_dead_cond(const oop obj,
1426 const HeapRegion* hr,
1427 const VerifyOption vo) const;
1428
1429 bool is_obj_dead_cond(const oop obj,
1430 const VerifyOption vo) const;
1431
1432 G1HeapSummary create_g1_heap_summary();
1433 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats);
1434
1435 // Printing
1436 private:
1437 void print_heap_regions() const;
1438 void print_regions_on(outputStream* st) const;
1439
1440 public:
1441 virtual void print_on(outputStream* st) const;
1442 virtual void print_extended_on(outputStream* st) const;
1443 virtual void print_on_error(outputStream* st) const;
1444
1445 virtual void print_gc_threads_on(outputStream* st) const;
1446 virtual void gc_threads_do(ThreadClosure* tc) const;
1447
1448 // Override
1449 void print_tracing_info() const;
1450
1451 // The following two methods are helpful for debugging RSet issues.
1452 void print_cset_rsets() PRODUCT_RETURN;
1453 void print_all_rsets() PRODUCT_RETURN;
1454
1455 // Used to print information about locations in the hs_err file.
1456 virtual bool print_location(outputStream* st, void* addr) const;
1457
1458 size_t pending_card_num();
1459 };
1460
1461 class G1ParEvacuateFollowersClosure : public VoidClosure {
1462 private:
1463 double _start_term;
1464 double _term_time;
1465 size_t _term_attempts;
1466
1467 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
1468 void end_term_time() { _term_time += (os::elapsedTime() - _start_term); }
1469 protected:
1470 G1CollectedHeap* _g1h;
1471 G1ParScanThreadState* _par_scan_state;
1472 RefToScanQueueSet* _queues;
1473 ParallelTaskTerminator* _terminator;
1474 G1GCPhaseTimes::GCParPhases _phase;
1475
1476 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
1477 RefToScanQueueSet* queues() { return _queues; }
1478 ParallelTaskTerminator* terminator() { return _terminator; }
1479
1480 public:
1481 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
1482 G1ParScanThreadState* par_scan_state,
1483 RefToScanQueueSet* queues,
1484 ParallelTaskTerminator* terminator,
1485 G1GCPhaseTimes::GCParPhases phase)
1486 : _start_term(0.0), _term_time(0.0), _term_attempts(0),
1487 _g1h(g1h), _par_scan_state(par_scan_state),
1488 _queues(queues), _terminator(terminator), _phase(phase) {}
1489
1490 void do_void();
1491
1492 double term_time() const { return _term_time; }
1493 size_t term_attempts() const { return _term_attempts; }
1494
1495 private:
1496 inline bool offer_termination();
1497 };
1498
1499 #endif // SHARE_GC_G1_G1COLLECTEDHEAP_HPP