1 /*
2 * Copyright (c) 2001, 2021, 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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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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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/g1GCPauseType.hpp"
40 #include "gc/g1/g1HeapTransition.hpp"
41 #include "gc/g1/g1HeapVerifier.hpp"
42 #include "gc/g1/g1HRPrinter.hpp"
43 #include "gc/g1/g1HeapRegionAttr.hpp"
44 #include "gc/g1/g1MonitoringSupport.hpp"
45 #include "gc/g1/g1NUMA.hpp"
46 #include "gc/g1/g1RedirtyCardsQueue.hpp"
47 #include "gc/g1/g1SurvivorRegions.hpp"
48 #include "gc/g1/heapRegionManager.hpp"
49 #include "gc/g1/heapRegionSet.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 "gc/shared/taskqueue.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 G1BatchedGangTask;
78 class G1CardTableEntryClosure;
79 class G1CollectionSet;
80 class G1Policy;
81 class G1HotCardCache;
82 class G1RemSet;
83 class G1ServiceTask;
84 class G1ServiceThread;
85 class G1ConcurrentMark;
86 class G1ConcurrentMarkThread;
87 class G1ConcurrentRefine;
88 class GenerationCounters;
89 class STWGCTimer;
90 class SlidingForwarding;
91 class G1NewTracer;
92 class EvacuationFailedInfo;
93 class nmethod;
94 class WorkGang;
95 class G1Allocator;
96 class G1ArchiveAllocator;
97 class G1FullGCScope;
98 class G1HeapVerifier;
99 class G1HeapSizingPolicy;
100 class G1HeapSummary;
101 class G1EvacSummary;
102
103 typedef OverflowTaskQueue<ScannerTask, mtGC> G1ScannerTasksQueue;
104 typedef GenericTaskQueueSet<G1ScannerTasksQueue, mtGC> G1ScannerTasksQueueSet;
105
106 typedef int RegionIdx_t; // needs to hold [ 0..max_reserved_regions() )
107 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
108
109 // The G1 STW is alive closure.
110 // An instance is embedded into the G1CH and used as the
111 // (optional) _is_alive_non_header closure in the STW
112 // reference processor. It is also extensively used during
113 // reference processing during STW evacuation pauses.
114 class G1STWIsAliveClosure : public BoolObjectClosure {
115 G1CollectedHeap* _g1h;
116 public:
117 G1STWIsAliveClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
118 bool do_object_b(oop p);
119 };
120
121 class G1STWSubjectToDiscoveryClosure : public BoolObjectClosure {
122 G1CollectedHeap* _g1h;
123 public:
124 G1STWSubjectToDiscoveryClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
125 bool do_object_b(oop p);
126 };
127
128 class G1RegionMappingChangedListener : public G1MappingChangedListener {
129 private:
130 void reset_from_card_cache(uint start_idx, size_t num_regions);
131 public:
132 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
133 };
134
135 class G1CollectedHeap : public CollectedHeap {
136 friend class VM_CollectForMetadataAllocation;
137 friend class VM_G1CollectForAllocation;
138 friend class VM_G1CollectFull;
139 friend class VM_G1TryInitiateConcMark;
140 friend class VMStructs;
141 friend class MutatorAllocRegion;
142 friend class G1FullCollector;
143 friend class G1GCAllocRegion;
144 friend class G1HeapVerifier;
145
146 // Closures used in implementation.
147 friend class G1ParScanThreadState;
148 friend class G1ParScanThreadStateSet;
149 friend class G1EvacuateRegionsTask;
150 friend class G1PLABAllocator;
151
152 // Other related classes.
153 friend class HeapRegionClaimer;
154
155 // Testing classes.
156 friend class G1CheckRegionAttrTableClosure;
157
158 private:
159 G1ServiceThread* _service_thread;
160 G1ServiceTask* _periodic_gc_task;
161
162 WorkGang* _workers;
163 G1CardTable* _card_table;
164
165 Ticks _collection_pause_end;
166
167 SoftRefPolicy _soft_ref_policy;
168
169 static size_t _humongous_object_threshold_in_words;
170
171 // These sets keep track of old, archive and humongous regions respectively.
172 HeapRegionSet _old_set;
173 HeapRegionSet _archive_set;
174 HeapRegionSet _humongous_set;
175
176 void rebuild_free_region_list();
177 // Start a new incremental collection set for the next pause.
178 void start_new_collection_set();
179
180 // The block offset table for the G1 heap.
181 G1BlockOffsetTable* _bot;
182
183 public:
184 void prepare_region_for_full_compaction(HeapRegion* hr);
185
186 private:
187 // Rebuilds the region sets / lists so that they are repopulated to
188 // reflect the contents of the heap. The only exception is the
189 // humongous set which was not torn down in the first place. If
190 // free_list_only is true, it will only rebuild the free list.
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 // Number of bytes used in all regions during GC. Typically changed when
218 // retiring a GC alloc region.
219 size_t _bytes_used_during_gc;
220
221 // Class that handles archive allocation ranges.
222 G1ArchiveAllocator* _archive_allocator;
223
224 // GC allocation statistics policy for survivors.
225 G1EvacStats _survivor_evac_stats;
226
227 // GC allocation statistics policy for tenured objects.
228 G1EvacStats _old_evac_stats;
229
230 // It specifies whether we should attempt to expand the heap after a
231 // region allocation failure. If heap expansion fails we set this to
232 // false so that we don't re-attempt the heap expansion (it's likely
233 // that subsequent expansion attempts will also fail if one fails).
234 // Currently, it is only consulted during GC and it's reset at the
235 // start of each GC.
236 bool _expand_heap_after_alloc_failure;
237
238 // Helper for monitoring and management support.
239 G1MonitoringSupport* _g1mm;
240
241 SlidingForwarding* _forwarding;
242
243 // Records whether the region at the given index is (still) a
244 // candidate for eager reclaim. Only valid for humongous start
245 // regions; other regions have unspecified values. Humongous start
246 // regions are initialized at start of collection pause, with
247 // candidates removed from the set as they are found reachable from
248 // roots or the young generation.
249 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> {
250 protected:
251 bool default_value() const { return false; }
252 public:
253 void clear() { G1BiasedMappedArray<bool>::clear(); }
254 void set_candidate(uint region, bool value) {
255 set_by_index(region, value);
256 }
257 bool is_candidate(uint region) {
258 return get_by_index(region);
259 }
260 };
261
262 HumongousReclaimCandidates _humongous_reclaim_candidates;
263 uint _num_humongous_objects; // Current amount of (all) humongous objects found in the heap.
264 uint _num_humongous_reclaim_candidates; // Number of humongous object eager reclaim candidates.
265 public:
266 uint num_humongous_objects() const { return _num_humongous_objects; }
267 uint num_humongous_reclaim_candidates() const { return _num_humongous_reclaim_candidates; }
268 bool has_humongous_reclaim_candidates() const { return _num_humongous_reclaim_candidates > 0; }
269
270 bool should_do_eager_reclaim() const;
271
272 SlidingForwarding* forwarding() const {
273 return _forwarding;
274 }
275
276 private:
277
278 G1HRPrinter _hr_printer;
279
280 // Return true if an explicit GC should start a concurrent cycle instead
281 // of doing a STW full GC. A concurrent cycle should be started if:
282 // (a) cause == _g1_humongous_allocation,
283 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent,
284 // (c) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent,
285 // (d) cause == _wb_conc_mark or _wb_breakpoint,
286 // (e) cause == _g1_periodic_collection and +G1PeriodicGCInvokesConcurrent.
287 bool should_do_concurrent_full_gc(GCCause::Cause cause);
288
289 // Attempt to start a concurrent cycle with the indicated cause.
290 // precondition: should_do_concurrent_full_gc(cause)
291 bool try_collect_concurrently(GCCause::Cause cause,
292 uint gc_counter,
293 uint old_marking_started_before);
294
295 // indicates whether we are in young or mixed GC mode
296 G1CollectorState _collector_state;
297
298 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
299 // concurrent cycles) we have started.
300 volatile uint _old_marking_cycles_started;
301
302 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
303 // concurrent cycles) we have completed.
304 volatile uint _old_marking_cycles_completed;
305
306 // This is a non-product method that is helpful for testing. It is
307 // called at the end of a GC and artificially expands the heap by
308 // allocating a number of dead regions. This way we can induce very
309 // frequent marking cycles and stress the cleanup / concurrent
310 // cleanup code more (as all the regions that will be allocated by
311 // this method will be found dead by the marking cycle).
312 void allocate_dummy_regions() PRODUCT_RETURN;
313
314 // If the HR printer is active, dump the state of the regions in the
315 // heap after a compaction.
316 void print_hrm_post_compaction();
317
318 // Create a memory mapper for auxiliary data structures of the given size and
319 // translation factor.
320 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description,
321 size_t size,
322 size_t translation_factor);
323
324 void trace_heap(GCWhen::Type when, const GCTracer* tracer);
325
326 // These are macros so that, if the assert fires, we get the correct
327 // line number, file, etc.
328
329 #define heap_locking_asserts_params(_extra_message_) \
330 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
331 (_extra_message_), \
332 BOOL_TO_STR(Heap_lock->owned_by_self()), \
333 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
334 BOOL_TO_STR(Thread::current()->is_VM_thread())
335
336 #define assert_heap_locked() \
337 do { \
338 assert(Heap_lock->owned_by_self(), \
339 heap_locking_asserts_params("should be holding the Heap_lock")); \
340 } while (0)
341
342 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
343 do { \
344 assert(Heap_lock->owned_by_self() || \
345 (SafepointSynchronize::is_at_safepoint() && \
346 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
347 heap_locking_asserts_params("should be holding the Heap_lock or " \
348 "should be at a safepoint")); \
349 } while (0)
350
351 #define assert_heap_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 be holding the Heap_lock and " \
356 "should not be at a safepoint")); \
357 } while (0)
358
359 #define assert_heap_not_locked() \
360 do { \
361 assert(!Heap_lock->owned_by_self(), \
362 heap_locking_asserts_params("should not be holding the Heap_lock")); \
363 } while (0)
364
365 #define assert_heap_not_locked_and_not_at_safepoint() \
366 do { \
367 assert(!Heap_lock->owned_by_self() && \
368 !SafepointSynchronize::is_at_safepoint(), \
369 heap_locking_asserts_params("should not be holding the Heap_lock and " \
370 "should not be at a safepoint")); \
371 } while (0)
372
373 #define assert_at_safepoint_on_vm_thread() \
374 do { \
375 assert_at_safepoint(); \
376 assert(Thread::current_or_null() != NULL, "no current thread"); \
377 assert(Thread::current()->is_VM_thread(), "current thread is not VM thread"); \
378 } while (0)
379
380 #ifdef ASSERT
381 #define assert_used_and_recalculate_used_equal(g1h) \
382 do { \
383 size_t cur_used_bytes = g1h->used(); \
384 size_t recal_used_bytes = g1h->recalculate_used(); \
385 assert(cur_used_bytes == recal_used_bytes, "Used(" SIZE_FORMAT ") is not" \
386 " same as recalculated used(" SIZE_FORMAT ").", \
387 cur_used_bytes, recal_used_bytes); \
388 } while (0)
389 #else
390 #define assert_used_and_recalculate_used_equal(g1h) do {} while(0)
391 #endif
392
393 static const uint MaxYoungGCNameLength = 128;
394 // Sets given young_gc_name to the canonical young gc pause string. Young_gc_name
395 // must be at least of length MaxYoungGCNameLength.
396 void set_young_gc_name(char* young_gc_name);
397
398 // The young region list.
399 G1EdenRegions _eden;
400 G1SurvivorRegions _survivor;
401
402 STWGCTimer* _gc_timer_stw;
403
404 G1NewTracer* _gc_tracer_stw;
405
406 void gc_tracer_report_gc_start();
407 void gc_tracer_report_gc_end(bool concurrent_operation_is_full_mark, G1EvacuationInfo& evacuation_info);
408
409 // The current policy object for the collector.
410 G1Policy* _policy;
411 G1HeapSizingPolicy* _heap_sizing_policy;
412
413 G1CollectionSet _collection_set;
414
415 // Try to allocate a single non-humongous HeapRegion sufficient for
416 // an allocation of the given word_size. If do_expand is true,
417 // attempt to expand the heap if necessary to satisfy the allocation
418 // request. 'type' takes the type of region to be allocated. (Use constants
419 // Old, Eden, Humongous, Survivor defined in HeapRegionType.)
420 HeapRegion* new_region(size_t word_size,
421 HeapRegionType type,
422 bool do_expand,
423 uint node_index = G1NUMA::AnyNodeIndex);
424
425 // Initialize a contiguous set of free regions of length num_regions
426 // and starting at index first so that they appear as a single
427 // humongous region.
428 HeapWord* humongous_obj_allocate_initialize_regions(HeapRegion* first_hr,
429 uint num_regions,
430 size_t word_size);
431
432 // Attempt to allocate a humongous object of the given size. Return
433 // NULL if unsuccessful.
434 HeapWord* humongous_obj_allocate(size_t word_size);
435
436 // The following two methods, allocate_new_tlab() and
437 // mem_allocate(), are the two main entry points from the runtime
438 // into the G1's allocation routines. They have the following
439 // assumptions:
440 //
441 // * They should both be called outside safepoints.
442 //
443 // * They should both be called without holding the Heap_lock.
444 //
445 // * All allocation requests for new TLABs should go to
446 // allocate_new_tlab().
447 //
448 // * All non-TLAB allocation requests should go to mem_allocate().
449 //
450 // * If either call cannot satisfy the allocation request using the
451 // current allocating region, they will try to get a new one. If
452 // this fails, they will attempt to do an evacuation pause and
453 // retry the allocation.
454 //
455 // * If all allocation attempts fail, even after trying to schedule
456 // an evacuation pause, allocate_new_tlab() will return NULL,
457 // whereas mem_allocate() will attempt a heap expansion and/or
458 // schedule a Full GC.
459 //
460 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
461 // should never be called with word_size being humongous. All
462 // humongous allocation requests should go to mem_allocate() which
463 // will satisfy them with a special path.
464
465 virtual HeapWord* allocate_new_tlab(size_t min_size,
466 size_t requested_size,
467 size_t* actual_size);
468
469 virtual HeapWord* mem_allocate(size_t word_size,
470 bool* gc_overhead_limit_was_exceeded);
471
472 // First-level mutator allocation attempt: try to allocate out of
473 // the mutator alloc region without taking the Heap_lock. This
474 // should only be used for non-humongous allocations.
475 inline HeapWord* attempt_allocation(size_t min_word_size,
476 size_t desired_word_size,
477 size_t* actual_word_size);
478
479 // Second-level mutator allocation attempt: take the Heap_lock and
480 // retry the allocation attempt, potentially scheduling a GC
481 // pause. This should only be used for non-humongous allocations.
482 HeapWord* attempt_allocation_slow(size_t word_size);
483
484 // Takes the Heap_lock and attempts a humongous allocation. It can
485 // potentially schedule a GC pause.
486 HeapWord* attempt_allocation_humongous(size_t word_size);
487
488 // Allocation attempt that should be called during safepoints (e.g.,
489 // at the end of a successful GC). expect_null_mutator_alloc_region
490 // specifies whether the mutator alloc region is expected to be NULL
491 // or not.
492 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
493 bool expect_null_mutator_alloc_region);
494
495 // These methods are the "callbacks" from the G1AllocRegion class.
496
497 // For mutator alloc regions.
498 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force, uint node_index);
499 void retire_mutator_alloc_region(HeapRegion* alloc_region,
500 size_t allocated_bytes);
501
502 // For GC alloc regions.
503 bool has_more_regions(G1HeapRegionAttr dest);
504 HeapRegion* new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index);
505 void retire_gc_alloc_region(HeapRegion* alloc_region,
506 size_t allocated_bytes, G1HeapRegionAttr dest);
507
508 // - if explicit_gc is true, the GC is for a System.gc() etc,
509 // otherwise it's for a failed allocation.
510 // - if clear_all_soft_refs is true, all soft references should be
511 // cleared during the GC.
512 // - if do_maximum_compaction is true, full gc will do a maximally
513 // compacting collection, leaving no dead wood.
514 // - it returns false if it is unable to do the collection due to the
515 // GC locker being active, true otherwise.
516 bool do_full_collection(bool explicit_gc,
517 bool clear_all_soft_refs,
518 bool do_maximum_compaction);
519
520 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread.
521 virtual void do_full_collection(bool clear_all_soft_refs);
522
523 // Helper to do a full collection that clears soft references.
524 bool upgrade_to_full_collection();
525
526 // Callback from VM_G1CollectForAllocation operation.
527 // This function does everything necessary/possible to satisfy a
528 // failed allocation request (including collection, expansion, etc.)
529 HeapWord* satisfy_failed_allocation(size_t word_size,
530 bool* succeeded);
531 // Internal helpers used during full GC to split it up to
532 // increase readability.
533 void abort_concurrent_cycle();
534 void verify_before_full_collection(bool explicit_gc);
535 void prepare_heap_for_full_collection();
536 void prepare_heap_for_mutators();
537 void abort_refinement();
538 void verify_after_full_collection();
539 void print_heap_after_full_collection(G1HeapTransition* heap_transition);
540
541 // Helper method for satisfy_failed_allocation()
542 HeapWord* satisfy_failed_allocation_helper(size_t word_size,
543 bool do_gc,
544 bool maximum_compaction,
545 bool expect_null_mutator_alloc_region,
546 bool* gc_succeeded);
547
548 // Attempting to expand the heap sufficiently
549 // to support an allocation of the given "word_size". If
550 // successful, perform the allocation and return the address of the
551 // allocated block, or else "NULL".
552 HeapWord* expand_and_allocate(size_t word_size);
553
554 // Process any reference objects discovered.
555 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states);
556
557 // If during a concurrent start pause we may install a pending list head which is not
558 // otherwise reachable, ensure that it is marked in the bitmap for concurrent marking
559 // to discover.
560 void make_pending_list_reachable();
561
562 void verify_numa_regions(const char* desc);
563
564 public:
565 G1ServiceThread* service_thread() const { return _service_thread; }
566
567 WorkGang* workers() const { return _workers; }
568
569 // Runs the given AbstractGangTask with the current active workers,
570 // returning the total time taken.
571 Tickspan run_task_timed(AbstractGangTask* task);
572 // Run the given batch task using the work gang.
573 void run_batch_task(G1BatchedGangTask* cl);
574
575 G1Allocator* allocator() {
576 return _allocator;
577 }
578
579 G1HeapVerifier* verifier() {
580 return _verifier;
581 }
582
583 G1MonitoringSupport* g1mm() {
584 assert(_g1mm != NULL, "should have been initialized");
585 return _g1mm;
586 }
587
588 void resize_heap_if_necessary();
589
590 // Check if there is memory to uncommit and if so schedule a task to do it.
591 void uncommit_regions_if_necessary();
592 // Immediately uncommit uncommittable regions.
593 uint uncommit_regions(uint region_limit);
594 bool has_uncommittable_regions();
595
596 G1NUMA* numa() const { return _numa; }
597
598 // Expand the garbage-first heap by at least the given size (in bytes!).
599 // Returns true if the heap was expanded by the requested amount;
600 // false otherwise.
601 // (Rounds up to a HeapRegion boundary.)
602 bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL);
603 bool expand_single_region(uint node_index);
604
605 // Returns the PLAB statistics for a given destination.
606 inline G1EvacStats* alloc_buffer_stats(G1HeapRegionAttr dest);
607
608 // Determines PLAB size for a given destination.
609 inline size_t desired_plab_sz(G1HeapRegionAttr dest);
610
611 // Do anything common to GC's.
612 void gc_prologue(bool full);
613 void gc_epilogue(bool full);
614
615 // Does the given region fulfill remembered set based eager reclaim candidate requirements?
616 bool is_potential_eager_reclaim_candidate(HeapRegion* r) const;
617
618 // Modify the reclaim candidate set and test for presence.
619 // These are only valid for starts_humongous regions.
620 inline void set_humongous_reclaim_candidate(uint region, bool value);
621 inline bool is_humongous_reclaim_candidate(uint region);
622
623 // Remove from the reclaim candidate set. Also remove from the
624 // collection set so that later encounters avoid the slow path.
625 inline void set_humongous_is_live(oop obj);
626
627 // Register the given region to be part of the collection set.
628 inline void register_humongous_region_with_region_attr(uint index);
629
630 // We register a region with the fast "in collection set" test. We
631 // simply set to true the array slot corresponding to this region.
632 void register_young_region_with_region_attr(HeapRegion* r) {
633 _region_attr.set_in_young(r->hrm_index());
634 }
635 inline void register_region_with_region_attr(HeapRegion* r);
636 inline void register_old_region_with_region_attr(HeapRegion* r);
637 inline void register_optional_region_with_region_attr(HeapRegion* r);
638
639 void clear_region_attr(const HeapRegion* hr) {
640 _region_attr.clear(hr);
641 }
642
643 void clear_region_attr() {
644 _region_attr.clear();
645 }
646
647 // Verify that the G1RegionAttr remset tracking corresponds to actual remset tracking
648 // for all regions.
649 void verify_region_attr_remset_update() PRODUCT_RETURN;
650
651 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause);
652
653 // This is called at the start of either a concurrent cycle or a Full
654 // GC to update the number of old marking cycles started.
655 void increment_old_marking_cycles_started();
656
657 // This is called at the end of either a concurrent cycle or a Full
658 // GC to update the number of old marking cycles completed. Those two
659 // can happen in a nested fashion, i.e., we start a concurrent
660 // cycle, a Full GC happens half-way through it which ends first,
661 // and then the cycle notices that a Full GC happened and ends
662 // too. The concurrent parameter is a boolean to help us do a bit
663 // tighter consistency checking in the method. If concurrent is
664 // false, the caller is the inner caller in the nesting (i.e., the
665 // Full GC). If concurrent is true, the caller is the outer caller
666 // in this nesting (i.e., the concurrent cycle). Further nesting is
667 // not currently supported. The end of this call also notifies
668 // the G1OldGCCount_lock in case a Java thread is waiting for a full
669 // GC to happen (e.g., it called System.gc() with
670 // +ExplicitGCInvokesConcurrent).
671 // whole_heap_examined should indicate that during that old marking
672 // cycle the whole heap has been examined for live objects (as opposed
673 // to only parts, or aborted before completion).
674 void increment_old_marking_cycles_completed(bool concurrent, bool whole_heap_examined);
675
676 uint old_marking_cycles_completed() {
677 return _old_marking_cycles_completed;
678 }
679
680 G1HRPrinter* hr_printer() { return &_hr_printer; }
681
682 // Allocates a new heap region instance.
683 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr);
684
685 // Allocate the highest free region in the reserved heap. This will commit
686 // regions as necessary.
687 HeapRegion* alloc_highest_free_region();
688
689 // Frees a region by resetting its metadata and adding it to the free list
690 // passed as a parameter (this is usually a local list which will be appended
691 // to the master free list later or NULL if free list management is handled
692 // in another way).
693 // Callers must ensure they are the only one calling free on the given region
694 // at the same time.
695 void free_region(HeapRegion* hr, FreeRegionList* free_list);
696
697 // It dirties the cards that cover the block so that the post
698 // write barrier never queues anything when updating objects on this
699 // block. It is assumed (and in fact we assert) that the block
700 // belongs to a young region.
701 inline void dirty_young_block(HeapWord* start, size_t word_size);
702
703 // Frees a humongous region by collapsing it into individual regions
704 // and calling free_region() for each of them. The freed regions
705 // will be added to the free list that's passed as a parameter (this
706 // is usually a local list which will be appended to the master free
707 // list later).
708 // The method assumes that only a single thread is ever calling
709 // this for a particular region at once.
710 void free_humongous_region(HeapRegion* hr,
711 FreeRegionList* free_list);
712
713 // Facility for allocating in 'archive' regions in high heap memory and
714 // recording the allocated ranges. These should all be called from the
715 // VM thread at safepoints, without the heap lock held. They can be used
716 // to create and archive a set of heap regions which can be mapped at the
717 // same fixed addresses in a subsequent JVM invocation.
718 void begin_archive_alloc_range(bool open = false);
719
720 // Check if the requested size would be too large for an archive allocation.
721 bool is_archive_alloc_too_large(size_t word_size);
722
723 // Allocate memory of the requested size from the archive region. This will
724 // return NULL if the size is too large or if no memory is available. It
725 // does not trigger a garbage collection.
726 HeapWord* archive_mem_allocate(size_t word_size);
727
728 // Optionally aligns the end address and returns the allocated ranges in
729 // an array of MemRegions in order of ascending addresses.
730 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
731 size_t end_alignment_in_bytes = 0);
732
733 // Facility for allocating a fixed range within the heap and marking
734 // the containing regions as 'archive'. For use at JVM init time, when the
735 // caller may mmap archived heap data at the specified range(s).
736 // Verify that the MemRegions specified in the argument array are within the
737 // reserved heap.
738 bool check_archive_addresses(MemRegion* range, size_t count);
739
740 // Commit the appropriate G1 regions containing the specified MemRegions
741 // and mark them as 'archive' regions. The regions in the array must be
742 // non-overlapping and in order of ascending address.
743 bool alloc_archive_regions(MemRegion* range, size_t count, bool open);
744
745 // Insert any required filler objects in the G1 regions around the specified
746 // ranges to make the regions parseable. This must be called after
747 // alloc_archive_regions, and after class loading has occurred.
748 void fill_archive_regions(MemRegion* range, size_t count);
749
750 // Populate the G1BlockOffsetTablePart for archived regions with the given
751 // memory ranges.
752 void populate_archive_regions_bot_part(MemRegion* range, size_t count);
753
754 // For each of the specified MemRegions, uncommit the containing G1 regions
755 // which had been allocated by alloc_archive_regions. This should be called
756 // rather than fill_archive_regions at JVM init time if the archive file
757 // mapping failed, with the same non-overlapping and sorted MemRegion array.
758 void dealloc_archive_regions(MemRegion* range, size_t count);
759
760 private:
761
762 // Shrink the garbage-first heap by at most the given size (in bytes!).
763 // (Rounds down to a HeapRegion boundary.)
764 void shrink(size_t shrink_bytes);
765 void shrink_helper(size_t expand_bytes);
766
767 #if TASKQUEUE_STATS
768 static void print_taskqueue_stats_hdr(outputStream* const st);
769 void print_taskqueue_stats() const;
770 void reset_taskqueue_stats();
771 #endif // TASKQUEUE_STATS
772
773 // Start a concurrent cycle.
774 void start_concurrent_cycle(bool concurrent_operation_is_full_mark);
775
776 // Schedule the VM operation that will do an evacuation pause to
777 // satisfy an allocation request of word_size. *succeeded will
778 // return whether the VM operation was successful (it did do an
779 // evacuation pause) or not (another thread beat us to it or the GC
780 // locker was active). Given that we should not be holding the
781 // Heap_lock when we enter this method, we will pass the
782 // gc_count_before (i.e., total_collections()) as a parameter since
783 // it has to be read while holding the Heap_lock. Currently, both
784 // methods that call do_collection_pause() release the Heap_lock
785 // before the call, so it's easy to read gc_count_before just before.
786 HeapWord* do_collection_pause(size_t word_size,
787 uint gc_count_before,
788 bool* succeeded,
789 GCCause::Cause gc_cause);
790
791 void wait_for_root_region_scanning();
792
793 // Perform an incremental collection at a safepoint, possibly
794 // followed by a by-policy upgrade to a full collection. Returns
795 // false if unable to do the collection due to the GC locker being
796 // active, true otherwise.
797 // precondition: at safepoint on VM thread
798 // precondition: !is_gc_active()
799 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
800
801 // Helper for do_collection_pause_at_safepoint, containing the guts
802 // of the incremental collection pause, executed by the vm thread.
803 void do_collection_pause_at_safepoint_helper(double target_pause_time_ms);
804
805 G1HeapVerifier::G1VerifyType young_collection_verify_type() const;
806 void verify_before_young_collection(G1HeapVerifier::G1VerifyType type);
807 void verify_after_young_collection(G1HeapVerifier::G1VerifyType type);
808
809 void calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms);
810
811 // Actually do the work of evacuating the parts of the collection set.
812 // The has_optional_evacuation_work flag for the initial collection set
813 // evacuation indicates whether one or more optional evacuation steps may
814 // follow.
815 // If not set, G1 can avoid clearing the card tables of regions that we scan
816 // for roots from the heap: when scanning the card table for dirty cards after
817 // all remembered sets have been dumped onto it, for optional evacuation we
818 // mark these cards as "Scanned" to know that we do not need to re-scan them
819 // in the additional optional evacuation passes. This means that in the "Clear
820 // Card Table" phase we need to clear those marks. However, if there is no
821 // optional evacuation, g1 can immediately clean the dirty cards it encounters
822 // as nobody else will be looking at them again, saving the clear card table
823 // work later.
824 // This case is very common (young only collections and most mixed gcs), so
825 // depending on the ratio between scanned and evacuated regions (which g1 always
826 // needs to clear), this is a big win.
827 void evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states,
828 bool has_optional_evacuation_work);
829 void evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states);
830 private:
831 // Evacuate the next set of optional regions.
832 void evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states);
833
834 public:
835 void pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss);
836 void post_evacuate_collection_set(G1EvacuationInfo& evacuation_info,
837 G1RedirtyCardsQueueSet* rdcqs,
838 G1ParScanThreadStateSet* pss);
839
840 void expand_heap_after_young_collection();
841 // Update object copying statistics.
842 void record_obj_copy_mem_stats();
843
844 // The hot card cache for remembered set insertion optimization.
845 G1HotCardCache* _hot_card_cache;
846
847 // The g1 remembered set of the heap.
848 G1RemSet* _rem_set;
849
850 void post_evacuate_cleanup_1(G1ParScanThreadStateSet* per_thread_states,
851 G1RedirtyCardsQueueSet* rdcqs);
852 void post_evacuate_cleanup_2(PreservedMarksSet* preserved_marks,
853 G1RedirtyCardsQueueSet* rdcqs,
854 G1EvacuationInfo* evacuation_info,
855 const size_t* surviving_young_words);
856
857 // After a collection pause, reset eden and the collection set.
858 void clear_eden();
859 void clear_collection_set();
860
861 // Abandon the current collection set without recording policy
862 // statistics or updating free lists.
863 void abandon_collection_set(G1CollectionSet* collection_set);
864
865 // The concurrent marker (and the thread it runs in.)
866 G1ConcurrentMark* _cm;
867 G1ConcurrentMarkThread* _cm_thread;
868
869 // The concurrent refiner.
870 G1ConcurrentRefine* _cr;
871
872 // The parallel task queues
873 G1ScannerTasksQueueSet *_task_queues;
874
875 // Number of regions evacuation failed in the current collection.
876 volatile uint _num_regions_failed_evacuation;
877 // Records for every region on the heap whether evacuation failed for it.
878 volatile bool* _regions_failed_evacuation;
879
880 EvacuationFailedInfo* _evacuation_failed_info_array;
881
882 PreservedMarksSet _preserved_marks_set;
883
884 // Preserve the mark of "obj", if necessary, in preparation for its mark
885 // word being overwritten with a self-forwarding-pointer.
886 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m);
887
888 #ifndef PRODUCT
889 // Support for forcing evacuation failures. Analogous to
890 // PromotionFailureALot for the other collectors.
891
892 // Records whether G1EvacuationFailureALot should be in effect
893 // for the current GC
894 bool _evacuation_failure_alot_for_current_gc;
895
896 // Used to record the GC number for interval checking when
897 // determining whether G1EvaucationFailureALot is in effect
898 // for the current GC.
899 size_t _evacuation_failure_alot_gc_number;
900
901 // Count of the number of evacuations between failures.
902 volatile size_t _evacuation_failure_alot_count;
903
904 // Set whether G1EvacuationFailureALot should be in effect
905 // for the current GC (based upon the type of GC and which
906 // command line flags are set);
907 inline bool evacuation_failure_alot_for_gc_type(bool for_young_gc,
908 bool during_concurrent_start,
909 bool mark_or_rebuild_in_progress);
910
911 inline void set_evacuation_failure_alot_for_current_gc();
912
913 // Return true if it's time to cause an evacuation failure.
914 inline bool evacuation_should_fail();
915
916 // Reset the G1EvacuationFailureALot counters. Should be called at
917 // the end of an evacuation pause in which an evacuation failure occurred.
918 inline void reset_evacuation_should_fail();
919 #endif // !PRODUCT
920
921 // ("Weak") Reference processing support.
922 //
923 // G1 has 2 instances of the reference processor class. One
924 // (_ref_processor_cm) handles reference object discovery
925 // and subsequent processing during concurrent marking cycles.
926 //
927 // The other (_ref_processor_stw) handles reference object
928 // discovery and processing during full GCs and incremental
929 // evacuation pauses.
930 //
931 // During an incremental pause, reference discovery will be
932 // temporarily disabled for _ref_processor_cm and will be
933 // enabled for _ref_processor_stw. At the end of the evacuation
934 // pause references discovered by _ref_processor_stw will be
935 // processed and discovery will be disabled. The previous
936 // setting for reference object discovery for _ref_processor_cm
937 // will be re-instated.
938 //
939 // At the start of marking:
940 // * Discovery by the CM ref processor is verified to be inactive
941 // and it's discovered lists are empty.
942 // * Discovery by the CM ref processor is then enabled.
943 //
944 // At the end of marking:
945 // * Any references on the CM ref processor's discovered
946 // lists are processed (possibly MT).
947 //
948 // At the start of full GC we:
949 // * Disable discovery by the CM ref processor and
950 // empty CM ref processor's discovered lists
951 // (without processing any entries).
952 // * Verify that the STW ref processor is inactive and it's
953 // discovered lists are empty.
954 // * Temporarily set STW ref processor discovery as single threaded.
955 // * Temporarily clear the STW ref processor's _is_alive_non_header
956 // field.
957 // * Finally enable discovery by the STW ref processor.
958 //
959 // The STW ref processor is used to record any discovered
960 // references during the full GC.
961 //
962 // At the end of a full GC we:
963 // * Enqueue any reference objects discovered by the STW ref processor
964 // that have non-live referents. This has the side-effect of
965 // making the STW ref processor inactive by disabling discovery.
966 // * Verify that the CM ref processor is still inactive
967 // and no references have been placed on it's discovered
968 // lists (also checked as a precondition during concurrent start).
969
970 // The (stw) reference processor...
971 ReferenceProcessor* _ref_processor_stw;
972
973 // During reference object discovery, the _is_alive_non_header
974 // closure (if non-null) is applied to the referent object to
975 // determine whether the referent is live. If so then the
976 // reference object does not need to be 'discovered' and can
977 // be treated as a regular oop. This has the benefit of reducing
978 // the number of 'discovered' reference objects that need to
979 // be processed.
980 //
981 // Instance of the is_alive closure for embedding into the
982 // STW reference processor as the _is_alive_non_header field.
983 // Supplying a value for the _is_alive_non_header field is
984 // optional but doing so prevents unnecessary additions to
985 // the discovered lists during reference discovery.
986 G1STWIsAliveClosure _is_alive_closure_stw;
987
988 G1STWSubjectToDiscoveryClosure _is_subject_to_discovery_stw;
989
990 // The (concurrent marking) reference processor...
991 ReferenceProcessor* _ref_processor_cm;
992
993 // Instance of the concurrent mark is_alive closure for embedding
994 // into the Concurrent Marking reference processor as the
995 // _is_alive_non_header field. Supplying a value for the
996 // _is_alive_non_header field is optional but doing so prevents
997 // unnecessary additions to the discovered lists during reference
998 // discovery.
999 G1CMIsAliveClosure _is_alive_closure_cm;
1000
1001 G1CMSubjectToDiscoveryClosure _is_subject_to_discovery_cm;
1002 public:
1003
1004 G1ScannerTasksQueue* task_queue(uint i) const;
1005
1006 uint num_task_queues() const;
1007
1008 // Create a G1CollectedHeap.
1009 // Must call the initialize method afterwards.
1010 // May not return if something goes wrong.
1011 G1CollectedHeap();
1012
1013 private:
1014 jint initialize_concurrent_refinement();
1015 jint initialize_service_thread();
1016 public:
1017 // Initialize the G1CollectedHeap to have the initial and
1018 // maximum sizes and remembered and barrier sets
1019 // specified by the policy object.
1020 jint initialize();
1021
1022 virtual void stop();
1023 virtual void safepoint_synchronize_begin();
1024 virtual void safepoint_synchronize_end();
1025
1026 // Does operations required after initialization has been done.
1027 void post_initialize();
1028
1029 // Initialize weak reference processing.
1030 void ref_processing_init();
1031
1032 virtual Name kind() const {
1033 return CollectedHeap::G1;
1034 }
1035
1036 virtual const char* name() const {
1037 return "G1";
1038 }
1039
1040 const G1CollectorState* collector_state() const { return &_collector_state; }
1041 G1CollectorState* collector_state() { return &_collector_state; }
1042
1043 // The current policy object for the collector.
1044 G1Policy* policy() const { return _policy; }
1045 // The remembered set.
1046 G1RemSet* rem_set() const { return _rem_set; }
1047
1048 inline G1GCPhaseTimes* phase_times() const;
1049
1050 const G1CollectionSet* collection_set() const { return &_collection_set; }
1051 G1CollectionSet* collection_set() { return &_collection_set; }
1052
1053 virtual SoftRefPolicy* soft_ref_policy();
1054
1055 virtual void initialize_serviceability();
1056 virtual MemoryUsage memory_usage();
1057 virtual GrowableArray<GCMemoryManager*> memory_managers();
1058 virtual GrowableArray<MemoryPool*> memory_pools();
1059
1060 // Try to minimize the remembered set.
1061 void scrub_rem_set();
1062
1063 // Apply the given closure on all cards in the Hot Card Cache, emptying it.
1064 void iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id);
1065
1066 // The shared block offset table array.
1067 G1BlockOffsetTable* bot() const { return _bot; }
1068
1069 // Reference Processing accessors
1070
1071 // The STW reference processor....
1072 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1073
1074 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; }
1075
1076 // The Concurrent Marking reference processor...
1077 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1078
1079 size_t unused_committed_regions_in_bytes() const;
1080
1081 virtual size_t capacity() const;
1082 virtual size_t used() const;
1083 // This should be called when we're not holding the heap lock. The
1084 // result might be a bit inaccurate.
1085 size_t used_unlocked() const;
1086 size_t recalculate_used() const;
1087
1088 // These virtual functions do the actual allocation.
1089 // Some heaps may offer a contiguous region for shared non-blocking
1090 // allocation, via inlined code (by exporting the address of the top and
1091 // end fields defining the extent of the contiguous allocation region.)
1092 // But G1CollectedHeap doesn't yet support this.
1093
1094 virtual bool is_maximal_no_gc() const {
1095 return _hrm.available() == 0;
1096 }
1097
1098 // Returns true if an incremental GC should be upgrade to a full gc. This
1099 // is done when there are no free regions and the heap can't be expanded.
1100 bool should_upgrade_to_full_gc() const {
1101 return is_maximal_no_gc() && num_free_regions() == 0;
1102 }
1103
1104 // The current number of regions in the heap.
1105 uint num_regions() const { return _hrm.length(); }
1106
1107 // The max number of regions reserved for the heap. Except for static array
1108 // sizing purposes you probably want to use max_regions().
1109 uint max_reserved_regions() const { return _hrm.reserved_length(); }
1110
1111 // Max number of regions that can be committed.
1112 uint max_regions() const { return _hrm.max_length(); }
1113
1114 // The number of regions that are completely free.
1115 uint num_free_regions() const { return _hrm.num_free_regions(); }
1116
1117 // The number of regions that can be allocated into.
1118 uint num_free_or_available_regions() const { return num_free_regions() + _hrm.available(); }
1119
1120 MemoryUsage get_auxiliary_data_memory_usage() const {
1121 return _hrm.get_auxiliary_data_memory_usage();
1122 }
1123
1124 // The number of regions that are not completely free.
1125 uint num_used_regions() const { return num_regions() - num_free_regions(); }
1126
1127 #ifdef ASSERT
1128 bool is_on_master_free_list(HeapRegion* hr) {
1129 return _hrm.is_free(hr);
1130 }
1131 #endif // ASSERT
1132
1133 inline void old_set_add(HeapRegion* hr);
1134 inline void old_set_remove(HeapRegion* hr);
1135
1136 inline void archive_set_add(HeapRegion* hr);
1137
1138 size_t non_young_capacity_bytes() {
1139 return (old_regions_count() + _archive_set.length() + humongous_regions_count()) * HeapRegion::GrainBytes;
1140 }
1141
1142 // Determine whether the given region is one that we are using as an
1143 // old GC alloc region.
1144 bool is_old_gc_alloc_region(HeapRegion* hr);
1145
1146 // Perform a collection of the heap; intended for use in implementing
1147 // "System.gc". This probably implies as full a collection as the
1148 // "CollectedHeap" supports.
1149 virtual void collect(GCCause::Cause cause);
1150
1151 // Perform a collection of the heap with the given cause.
1152 // Returns whether this collection actually executed.
1153 bool try_collect(GCCause::Cause cause);
1154
1155 // True iff an evacuation has failed in the most-recent collection.
1156 inline bool evacuation_failed() const;
1157 // True iff the given region encountered an evacuation failure in the most-recent
1158 // collection.
1159 inline bool evacuation_failed(uint region_idx) const;
1160
1161 inline uint num_regions_failed_evacuation() const;
1162 // Notify that the garbage collection encountered an evacuation failure in the
1163 // given region. Returns whether this has been the first occurrence of an evacuation
1164 // failure in that region.
1165 inline bool notify_region_failed_evacuation(uint const region_idx);
1166
1167 void remove_from_old_gen_sets(const uint old_regions_removed,
1168 const uint archive_regions_removed,
1169 const uint humongous_regions_removed);
1170 void prepend_to_freelist(FreeRegionList* list);
1171 void decrement_summary_bytes(size_t bytes);
1172
1173 virtual bool is_in(const void* p) const;
1174
1175 // Return "TRUE" iff the given object address is within the collection
1176 // set. Assumes that the reference points into the heap.
1177 inline bool is_in_cset(const HeapRegion *hr);
1178 inline bool is_in_cset(oop obj);
1179 inline bool is_in_cset(HeapWord* addr);
1180
1181 inline bool is_in_cset_or_humongous(const oop obj);
1182
1183 private:
1184 // This array is used for a quick test on whether a reference points into
1185 // the collection set or not. Each of the array's elements denotes whether the
1186 // corresponding region is in the collection set or not.
1187 G1HeapRegionAttrBiasedMappedArray _region_attr;
1188
1189 public:
1190
1191 inline G1HeapRegionAttr region_attr(const void* obj) const;
1192 inline G1HeapRegionAttr region_attr(uint idx) const;
1193
1194 MemRegion reserved() const {
1195 return _hrm.reserved();
1196 }
1197
1198 bool is_in_reserved(const void* addr) const {
1199 return reserved().contains(addr);
1200 }
1201
1202 G1HotCardCache* hot_card_cache() const { return _hot_card_cache; }
1203
1204 G1CardTable* card_table() const {
1205 return _card_table;
1206 }
1207
1208 // Iteration functions.
1209
1210 void object_iterate_parallel(ObjectClosure* cl, uint worker_id, HeapRegionClaimer* claimer);
1211
1212 // Iterate over all objects, calling "cl.do_object" on each.
1213 virtual void object_iterate(ObjectClosure* cl);
1214
1215 virtual ParallelObjectIterator* parallel_object_iterator(uint thread_num);
1216
1217 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
1218 virtual void keep_alive(oop obj);
1219
1220 // Iterate over heap regions, in address order, terminating the
1221 // iteration early if the "do_heap_region" method returns "true".
1222 void heap_region_iterate(HeapRegionClosure* blk) const;
1223
1224 // Return the region with the given index. It assumes the index is valid.
1225 inline HeapRegion* region_at(uint index) const;
1226 inline HeapRegion* region_at_or_null(uint index) const;
1227
1228 // Return the next region (by index) that is part of the same
1229 // humongous object that hr is part of.
1230 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const;
1231
1232 // Calculate the region index of the given address. Given address must be
1233 // within the heap.
1234 inline uint addr_to_region(HeapWord* addr) const;
1235
1236 inline HeapWord* bottom_addr_for_region(uint index) const;
1237
1238 // Two functions to iterate over the heap regions in parallel. Threads
1239 // compete using the HeapRegionClaimer to claim the regions before
1240 // applying the closure on them.
1241 // The _from_worker_offset version uses the HeapRegionClaimer and
1242 // the worker id to calculate a start offset to prevent all workers to
1243 // start from the point.
1244 void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
1245 HeapRegionClaimer* hrclaimer,
1246 uint worker_id) const;
1247
1248 void heap_region_par_iterate_from_start(HeapRegionClosure* cl,
1249 HeapRegionClaimer* hrclaimer) const;
1250
1251 // Iterate over all regions in the collection set in parallel.
1252 void collection_set_par_iterate_all(HeapRegionClosure* cl,
1253 HeapRegionClaimer* hr_claimer,
1254 uint worker_id);
1255
1256 // Iterate over all regions currently in the current collection set.
1257 void collection_set_iterate_all(HeapRegionClosure* blk);
1258
1259 // Iterate over the regions in the current increment of the collection set.
1260 // Starts the iteration so that the start regions of a given worker id over the
1261 // set active_workers are evenly spread across the set of collection set regions
1262 // to be iterated.
1263 // The variant with the HeapRegionClaimer guarantees that the closure will be
1264 // applied to a particular region exactly once.
1265 void collection_set_iterate_increment_from(HeapRegionClosure *blk, uint worker_id) {
1266 collection_set_iterate_increment_from(blk, NULL, worker_id);
1267 }
1268 void collection_set_iterate_increment_from(HeapRegionClosure *blk, HeapRegionClaimer* hr_claimer, uint worker_id);
1269
1270 // Returns the HeapRegion that contains addr. addr must not be NULL.
1271 template <class T>
1272 inline HeapRegion* heap_region_containing(const T addr) const;
1273
1274 // Returns the HeapRegion that contains addr, or NULL if that is an uncommitted
1275 // region. addr must not be NULL.
1276 template <class T>
1277 inline HeapRegion* heap_region_containing_or_null(const T addr) const;
1278
1279 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1280 // each address in the (reserved) heap is a member of exactly
1281 // one block. The defining characteristic of a block is that it is
1282 // possible to find its size, and thus to progress forward to the next
1283 // block. (Blocks may be of different sizes.) Thus, blocks may
1284 // represent Java objects, or they might be free blocks in a
1285 // free-list-based heap (or subheap), as long as the two kinds are
1286 // distinguishable and the size of each is determinable.
1287
1288 // Returns the address of the start of the "block" that contains the
1289 // address "addr". We say "blocks" instead of "object" since some heaps
1290 // may not pack objects densely; a chunk may either be an object or a
1291 // non-object.
1292 HeapWord* block_start(const void* addr) const;
1293
1294 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1295 // the block is an object.
1296 bool block_is_obj(const HeapWord* addr) const;
1297
1298 // Section on thread-local allocation buffers (TLABs)
1299 // See CollectedHeap for semantics.
1300
1301 size_t tlab_capacity(Thread* ignored) const;
1302 size_t tlab_used(Thread* ignored) const;
1303 size_t max_tlab_size() const;
1304 size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1305
1306 inline bool is_in_young(const oop obj);
1307
1308 // Returns "true" iff the given word_size is "very large".
1309 static bool is_humongous(size_t word_size) {
1310 // Note this has to be strictly greater-than as the TLABs
1311 // are capped at the humongous threshold and we want to
1312 // ensure that we don't try to allocate a TLAB as
1313 // humongous and that we don't allocate a humongous
1314 // object in a TLAB.
1315 return word_size > _humongous_object_threshold_in_words;
1316 }
1317
1318 // Returns the humongous threshold for a specific region size
1319 static size_t humongous_threshold_for(size_t region_size) {
1320 return (region_size / 2);
1321 }
1322
1323 // Returns the number of regions the humongous object of the given word size
1324 // requires.
1325 static size_t humongous_obj_size_in_regions(size_t word_size);
1326
1327 // Print the maximum heap capacity.
1328 virtual size_t max_capacity() const;
1329
1330 Tickspan time_since_last_collection() const { return Ticks::now() - _collection_pause_end; }
1331
1332 // Convenience function to be used in situations where the heap type can be
1333 // asserted to be this type.
1334 static G1CollectedHeap* heap() {
1335 return named_heap<G1CollectedHeap>(CollectedHeap::G1);
1336 }
1337
1338 void set_region_short_lived_locked(HeapRegion* hr);
1339 // add appropriate methods for any other surv rate groups
1340
1341 const G1SurvivorRegions* survivor() const { return &_survivor; }
1342
1343 uint eden_regions_count() const { return _eden.length(); }
1344 uint eden_regions_count(uint node_index) const { return _eden.regions_on_node(node_index); }
1345 uint survivor_regions_count() const { return _survivor.length(); }
1346 uint survivor_regions_count(uint node_index) const { return _survivor.regions_on_node(node_index); }
1347 size_t eden_regions_used_bytes() const { return _eden.used_bytes(); }
1348 size_t survivor_regions_used_bytes() const { return _survivor.used_bytes(); }
1349 uint young_regions_count() const { return _eden.length() + _survivor.length(); }
1350 uint old_regions_count() const { return _old_set.length(); }
1351 uint archive_regions_count() const { return _archive_set.length(); }
1352 uint humongous_regions_count() const { return _humongous_set.length(); }
1353
1354 #ifdef ASSERT
1355 bool check_young_list_empty();
1356 #endif
1357
1358 bool is_marked_next(oop obj) const;
1359
1360 // Determine if an object is dead, given the object and also
1361 // the region to which the object belongs.
1362 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1363 return hr->is_obj_dead(obj, _cm->prev_mark_bitmap());
1364 }
1365
1366 // This function returns true when an object has been
1367 // around since the previous marking and hasn't yet
1368 // been marked during this marking, and is not in a closed archive region.
1369 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1370 return
1371 !hr->obj_allocated_since_next_marking(obj) &&
1372 !is_marked_next(obj) &&
1373 !hr->is_closed_archive();
1374 }
1375
1376 // Determine if an object is dead, given only the object itself.
1377 // This will find the region to which the object belongs and
1378 // then call the region version of the same function.
1379
1380 // Added if it is NULL it isn't dead.
1381
1382 inline bool is_obj_dead(const oop obj) const;
1383
1384 inline bool is_obj_ill(const oop obj) const;
1385
1386 inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const;
1387 inline bool is_obj_dead_full(const oop obj) const;
1388
1389 G1ConcurrentMark* concurrent_mark() const { return _cm; }
1390
1391 // Refinement
1392
1393 G1ConcurrentRefine* concurrent_refine() const { return _cr; }
1394
1395 // Optimized nmethod scanning support routines
1396
1397 // Register the given nmethod with the G1 heap.
1398 virtual void register_nmethod(nmethod* nm);
1399
1400 // Unregister the given nmethod from the G1 heap.
1401 virtual void unregister_nmethod(nmethod* nm);
1402
1403 // No nmethod flushing needed.
1404 virtual void flush_nmethod(nmethod* nm) {}
1405
1406 // No nmethod verification implemented.
1407 virtual void verify_nmethod(nmethod* nm) {}
1408
1409 // Recalculate amount of used memory after GC. Must be called after all allocation
1410 // has finished.
1411 void update_used_after_gc();
1412 // Reset and re-enable the hot card cache.
1413 // Note the counts for the cards in the regions in the
1414 // collection set are reset when the collection set is freed.
1415 void reset_hot_card_cache();
1416 // Free up superfluous code root memory.
1417 void purge_code_root_memory();
1418
1419 // Rebuild the strong code root lists for each region
1420 // after a full GC.
1421 void rebuild_strong_code_roots();
1422
1423 // Performs cleaning of data structures after class unloading.
1424 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred);
1425
1426 // Verification
1427
1428 // Perform any cleanup actions necessary before allowing a verification.
1429 virtual void prepare_for_verify();
1430
1431 // Perform verification.
1432
1433 // vo == UsePrevMarking -> use "prev" marking information,
1434 // vo == UseNextMarking -> use "next" marking information
1435 // vo == UseFullMarking -> use "next" marking bitmap but no TAMS
1436 //
1437 // NOTE: Only the "prev" marking information is guaranteed to be
1438 // consistent most of the time, so most calls to this should use
1439 // vo == UsePrevMarking.
1440 // Currently, there is only one case where this is called with
1441 // vo == UseNextMarking, which is to verify the "next" marking
1442 // information at the end of remark.
1443 // Currently there is only one place where this is called with
1444 // vo == UseFullMarking, which is to verify the marking during a
1445 // full GC.
1446 void verify(VerifyOption vo);
1447
1448 // WhiteBox testing support.
1449 virtual bool supports_concurrent_gc_breakpoints() const;
1450
1451 virtual WorkGang* safepoint_workers() { return _workers; }
1452
1453 virtual bool is_archived_object(oop object) const;
1454
1455 // The methods below are here for convenience and dispatch the
1456 // appropriate method depending on value of the given VerifyOption
1457 // parameter. The values for that parameter, and their meanings,
1458 // are the same as those above.
1459
1460 bool is_obj_dead_cond(const oop obj,
1461 const HeapRegion* hr,
1462 const VerifyOption vo) const;
1463
1464 bool is_obj_dead_cond(const oop obj,
1465 const VerifyOption vo) const;
1466
1467 G1HeapSummary create_g1_heap_summary();
1468 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats);
1469
1470 // Printing
1471 private:
1472 void print_heap_regions() const;
1473 void print_regions_on(outputStream* st) const;
1474
1475 public:
1476 virtual void print_on(outputStream* st) const;
1477 virtual void print_extended_on(outputStream* st) const;
1478 virtual void print_on_error(outputStream* st) const;
1479
1480 virtual void gc_threads_do(ThreadClosure* tc) const;
1481
1482 // Override
1483 void print_tracing_info() const;
1484
1485 // The following two methods are helpful for debugging RSet issues.
1486 void print_cset_rsets() PRODUCT_RETURN;
1487 void print_all_rsets() PRODUCT_RETURN;
1488
1489 // Used to print information about locations in the hs_err file.
1490 virtual bool print_location(outputStream* st, void* addr) const;
1491 };
1492
1493 class G1ParEvacuateFollowersClosure : public VoidClosure {
1494 private:
1495 double _start_term;
1496 double _term_time;
1497 size_t _term_attempts;
1498
1499 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
1500 void end_term_time() { _term_time += (os::elapsedTime() - _start_term); }
1501 protected:
1502 G1CollectedHeap* _g1h;
1503 G1ParScanThreadState* _par_scan_state;
1504 G1ScannerTasksQueueSet* _queues;
1505 TaskTerminator* _terminator;
1506 G1GCPhaseTimes::GCParPhases _phase;
1507
1508 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
1509 G1ScannerTasksQueueSet* queues() { return _queues; }
1510 TaskTerminator* terminator() { return _terminator; }
1511
1512 public:
1513 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
1514 G1ParScanThreadState* par_scan_state,
1515 G1ScannerTasksQueueSet* queues,
1516 TaskTerminator* terminator,
1517 G1GCPhaseTimes::GCParPhases phase)
1518 : _start_term(0.0), _term_time(0.0), _term_attempts(0),
1519 _g1h(g1h), _par_scan_state(par_scan_state),
1520 _queues(queues), _terminator(terminator), _phase(phase) {}
1521
1522 void do_void();
1523
1524 double term_time() const { return _term_time; }
1525 size_t term_attempts() const { return _term_attempts; }
1526
1527 private:
1528 inline bool offer_termination();
1529 };
1530
1531 #endif // SHARE_GC_G1_G1COLLECTEDHEAP_HPP