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.
4 *
5 * This code is free software; you can redistribute it and/or modify it
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
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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 G1NewTracer;
91 class EvacuationFailedInfo;
92 class nmethod;
93 class WorkGang;
94 class G1Allocator;
95 class G1ArchiveAllocator;
96 class G1FullGCScope;
97 class G1HeapVerifier;
98 class G1HeapSizingPolicy;
99 class G1HeapSummary;
100 class G1EvacSummary;
101
102 typedef OverflowTaskQueue<ScannerTask, mtGC> G1ScannerTasksQueue;
103 typedef GenericTaskQueueSet<G1ScannerTasksQueue, mtGC> G1ScannerTasksQueueSet;
104
105 typedef int RegionIdx_t; // needs to hold [ 0..max_reserved_regions() )
106 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
107
108 // The G1 STW is alive closure.
109 // An instance is embedded into the G1CH and used as the
110 // (optional) _is_alive_non_header closure in the STW
111 // reference processor. It is also extensively used during
112 // reference processing during STW evacuation pauses.
113 class G1STWIsAliveClosure : public BoolObjectClosure {
114 G1CollectedHeap* _g1h;
115 public:
116 G1STWIsAliveClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
117 bool do_object_b(oop p);
118 };
119
120 class G1STWSubjectToDiscoveryClosure : public BoolObjectClosure {
121 G1CollectedHeap* _g1h;
122 public:
123 G1STWSubjectToDiscoveryClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
124 bool do_object_b(oop p);
125 };
126
127 class G1RegionMappingChangedListener : public G1MappingChangedListener {
128 private:
129 void reset_from_card_cache(uint start_idx, size_t num_regions);
130 public:
131 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
132 };
133
134 class G1CollectedHeap : public CollectedHeap {
135 friend class VM_CollectForMetadataAllocation;
136 friend class VM_G1CollectForAllocation;
137 friend class VM_G1CollectFull;
138 friend class VM_G1TryInitiateConcMark;
139 friend class VMStructs;
140 friend class MutatorAllocRegion;
141 friend class G1FullCollector;
142 friend class G1GCAllocRegion;
143 friend class G1HeapVerifier;
144
145 // Closures used in implementation.
146 friend class G1ParScanThreadState;
147 friend class G1ParScanThreadStateSet;
148 friend class G1EvacuateRegionsTask;
149 friend class G1PLABAllocator;
150
151 // Other related classes.
152 friend class HeapRegionClaimer;
153
154 // Testing classes.
155 friend class G1CheckRegionAttrTableClosure;
156
157 private:
158 G1ServiceThread* _service_thread;
159 G1ServiceTask* _periodic_gc_task;
160
161 WorkGang* _workers;
162 G1CardTable* _card_table;
163
164 Ticks _collection_pause_end;
165
166 SoftRefPolicy _soft_ref_policy;
167
168 static size_t _humongous_object_threshold_in_words;
169
170 // These sets keep track of old, archive and humongous regions respectively.
171 HeapRegionSet _old_set;
172 HeapRegionSet _archive_set;
173 HeapRegionSet _humongous_set;
174
175 void rebuild_free_region_list();
176 // Start a new incremental collection set for the next pause.
177 void start_new_collection_set();
178
179 // The block offset table for the G1 heap.
180 G1BlockOffsetTable* _bot;
181
182 public:
183 void prepare_region_for_full_compaction(HeapRegion* hr);
184
185 private:
186 // Rebuilds the region sets / lists so that they are repopulated to
187 // reflect the contents of the heap. The only exception is the
188 // humongous set which was not torn down in the first place. If
189 // free_list_only is true, it will only rebuild the free list.
190 void rebuild_region_sets(bool free_list_only);
191
192 // Callback for region mapping changed events.
193 G1RegionMappingChangedListener _listener;
194
195 // Handle G1 NUMA support.
196 G1NUMA* _numa;
197
198 // The sequence of all heap regions in the heap.
199 HeapRegionManager _hrm;
200
201 // Manages all allocations with regions except humongous object allocations.
202 G1Allocator* _allocator;
203
204 // Manages all heap verification.
205 G1HeapVerifier* _verifier;
206
207 // Outside of GC pauses, the number of bytes used in all regions other
208 // than the current allocation region(s).
209 volatile size_t _summary_bytes_used;
210
211 void increase_used(size_t bytes);
212 void decrease_used(size_t bytes);
213
214 void set_used(size_t bytes);
215
216 // Number of bytes used in all regions during GC. Typically changed when
217 // retiring a GC alloc region.
218 size_t _bytes_used_during_gc;
219
220 // Class that handles archive allocation ranges.
221 G1ArchiveAllocator* _archive_allocator;
222
223 // GC allocation statistics policy for survivors.
224 G1EvacStats _survivor_evac_stats;
225
226 // GC allocation statistics policy for tenured objects.
227 G1EvacStats _old_evac_stats;
228
229 // It specifies whether we should attempt to expand the heap after a
230 // region allocation failure. If heap expansion fails we set this to
231 // false so that we don't re-attempt the heap expansion (it's likely
232 // that subsequent expansion attempts will also fail if one fails).
233 // Currently, it is only consulted during GC and it's reset at the
234 // start of each GC.
235 bool _expand_heap_after_alloc_failure;
236
237 // Helper for monitoring and management support.
238 G1MonitoringSupport* _g1mm;
239
240 // Records whether the region at the given index is (still) a
241 // candidate for eager reclaim. Only valid for humongous start
242 // regions; other regions have unspecified values. Humongous start
243 // regions are initialized at start of collection pause, with
244 // candidates removed from the set as they are found reachable from
245 // roots or the young generation.
246 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> {
247 protected:
248 bool default_value() const { return false; }
249 public:
250 void clear() { G1BiasedMappedArray<bool>::clear(); }
251 void set_candidate(uint region, bool value) {
252 set_by_index(region, value);
253 }
254 bool is_candidate(uint region) {
255 return get_by_index(region);
256 }
257 };
258
259 HumongousReclaimCandidates _humongous_reclaim_candidates;
260 uint _num_humongous_objects; // Current amount of (all) humongous objects found in the heap.
261 uint _num_humongous_reclaim_candidates; // Number of humongous object eager reclaim candidates.
262 public:
263 uint num_humongous_objects() const { return _num_humongous_objects; }
264 uint num_humongous_reclaim_candidates() const { return _num_humongous_reclaim_candidates; }
265 bool has_humongous_reclaim_candidates() const { return _num_humongous_reclaim_candidates > 0; }
266
267 bool should_do_eager_reclaim() const;
268
269 private:
270
271 G1HRPrinter _hr_printer;
272
273 // Return true if an explicit GC should start a concurrent cycle instead
274 // of doing a STW full GC. A concurrent cycle should be started if:
275 // (a) cause == _g1_humongous_allocation,
276 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent,
277 // (c) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent,
278 // (d) cause == _wb_conc_mark or _wb_breakpoint,
279 // (e) cause == _g1_periodic_collection and +G1PeriodicGCInvokesConcurrent.
280 bool should_do_concurrent_full_gc(GCCause::Cause cause);
281
282 // Attempt to start a concurrent cycle with the indicated cause.
283 // precondition: should_do_concurrent_full_gc(cause)
284 bool try_collect_concurrently(GCCause::Cause cause,
285 uint gc_counter,
286 uint old_marking_started_before);
287
288 // indicates whether we are in young or mixed GC mode
289 G1CollectorState _collector_state;
290
291 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
292 // concurrent cycles) we have started.
293 volatile uint _old_marking_cycles_started;
294
295 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
296 // concurrent cycles) we have completed.
297 volatile uint _old_marking_cycles_completed;
298
299 // This is a non-product method that is helpful for testing. It is
300 // called at the end of a GC and artificially expands the heap by
301 // allocating a number of dead regions. This way we can induce very
302 // frequent marking cycles and stress the cleanup / concurrent
303 // cleanup code more (as all the regions that will be allocated by
304 // this method will be found dead by the marking cycle).
305 void allocate_dummy_regions() PRODUCT_RETURN;
306
307 // If the HR printer is active, dump the state of the regions in the
308 // heap after a compaction.
309 void print_hrm_post_compaction();
310
311 // Create a memory mapper for auxiliary data structures of the given size and
312 // translation factor.
313 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description,
314 size_t size,
315 size_t translation_factor);
316
317 void trace_heap(GCWhen::Type when, const GCTracer* tracer);
318
319 // These are macros so that, if the assert fires, we get the correct
320 // line number, file, etc.
321
322 #define heap_locking_asserts_params(_extra_message_) \
323 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
324 (_extra_message_), \
325 BOOL_TO_STR(Heap_lock->owned_by_self()), \
326 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
327 BOOL_TO_STR(Thread::current()->is_VM_thread())
328
329 #define assert_heap_locked() \
330 do { \
331 assert(Heap_lock->owned_by_self(), \
332 heap_locking_asserts_params("should be holding the Heap_lock")); \
333 } while (0)
334
335 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
336 do { \
337 assert(Heap_lock->owned_by_self() || \
338 (SafepointSynchronize::is_at_safepoint() && \
339 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
340 heap_locking_asserts_params("should be holding the Heap_lock or " \
341 "should be at a safepoint")); \
342 } while (0)
343
344 #define assert_heap_locked_and_not_at_safepoint() \
345 do { \
346 assert(Heap_lock->owned_by_self() && \
347 !SafepointSynchronize::is_at_safepoint(), \
348 heap_locking_asserts_params("should be holding the Heap_lock and " \
349 "should not be at a safepoint")); \
350 } while (0)
351
352 #define assert_heap_not_locked() \
353 do { \
354 assert(!Heap_lock->owned_by_self(), \
355 heap_locking_asserts_params("should not be holding the Heap_lock")); \
356 } while (0)
357
358 #define assert_heap_not_locked_and_not_at_safepoint() \
359 do { \
360 assert(!Heap_lock->owned_by_self() && \
361 !SafepointSynchronize::is_at_safepoint(), \
362 heap_locking_asserts_params("should not be holding the Heap_lock and " \
363 "should not be at a safepoint")); \
364 } while (0)
365
366 #define assert_at_safepoint_on_vm_thread() \
367 do { \
368 assert_at_safepoint(); \
369 assert(Thread::current_or_null() != NULL, "no current thread"); \
370 assert(Thread::current()->is_VM_thread(), "current thread is not VM thread"); \
371 } while (0)
372
373 #ifdef ASSERT
374 #define assert_used_and_recalculate_used_equal(g1h) \
375 do { \
376 size_t cur_used_bytes = g1h->used(); \
377 size_t recal_used_bytes = g1h->recalculate_used(); \
378 assert(cur_used_bytes == recal_used_bytes, "Used(" SIZE_FORMAT ") is not" \
379 " same as recalculated used(" SIZE_FORMAT ").", \
380 cur_used_bytes, recal_used_bytes); \
381 } while (0)
382 #else
383 #define assert_used_and_recalculate_used_equal(g1h) do {} while(0)
384 #endif
385
386 static const uint MaxYoungGCNameLength = 128;
387 // Sets given young_gc_name to the canonical young gc pause string. Young_gc_name
388 // must be at least of length MaxYoungGCNameLength.
389 void set_young_gc_name(char* young_gc_name);
390
391 // The young region list.
392 G1EdenRegions _eden;
393 G1SurvivorRegions _survivor;
394
395 STWGCTimer* _gc_timer_stw;
396
397 G1NewTracer* _gc_tracer_stw;
398
399 void gc_tracer_report_gc_start();
400 void gc_tracer_report_gc_end(bool concurrent_operation_is_full_mark, G1EvacuationInfo& evacuation_info);
401
402 // The current policy object for the collector.
403 G1Policy* _policy;
404 G1HeapSizingPolicy* _heap_sizing_policy;
405
406 G1CollectionSet _collection_set;
407
408 // Try to allocate a single non-humongous HeapRegion sufficient for
409 // an allocation of the given word_size. If do_expand is true,
410 // attempt to expand the heap if necessary to satisfy the allocation
411 // request. 'type' takes the type of region to be allocated. (Use constants
412 // Old, Eden, Humongous, Survivor defined in HeapRegionType.)
413 HeapRegion* new_region(size_t word_size,
414 HeapRegionType type,
415 bool do_expand,
416 uint node_index = G1NUMA::AnyNodeIndex);
417
418 // Initialize a contiguous set of free regions of length num_regions
419 // and starting at index first so that they appear as a single
420 // humongous region.
421 HeapWord* humongous_obj_allocate_initialize_regions(HeapRegion* first_hr,
422 uint num_regions,
423 size_t word_size);
424
425 // Attempt to allocate a humongous object of the given size. Return
426 // NULL if unsuccessful.
427 HeapWord* humongous_obj_allocate(size_t word_size);
428
429 // The following two methods, allocate_new_tlab() and
430 // mem_allocate(), are the two main entry points from the runtime
431 // into the G1's allocation routines. They have the following
432 // assumptions:
433 //
434 // * They should both be called outside safepoints.
435 //
436 // * They should both be called without holding the Heap_lock.
437 //
438 // * All allocation requests for new TLABs should go to
439 // allocate_new_tlab().
440 //
441 // * All non-TLAB allocation requests should go to mem_allocate().
442 //
443 // * If either call cannot satisfy the allocation request using the
444 // current allocating region, they will try to get a new one. If
445 // this fails, they will attempt to do an evacuation pause and
446 // retry the allocation.
447 //
448 // * If all allocation attempts fail, even after trying to schedule
449 // an evacuation pause, allocate_new_tlab() will return NULL,
450 // whereas mem_allocate() will attempt a heap expansion and/or
451 // schedule a Full GC.
452 //
453 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
454 // should never be called with word_size being humongous. All
455 // humongous allocation requests should go to mem_allocate() which
456 // will satisfy them with a special path.
457
458 virtual HeapWord* allocate_new_tlab(size_t min_size,
459 size_t requested_size,
460 size_t* actual_size);
461
462 virtual HeapWord* mem_allocate(size_t word_size,
463 bool* gc_overhead_limit_was_exceeded);
464
465 // First-level mutator allocation attempt: try to allocate out of
466 // the mutator alloc region without taking the Heap_lock. This
467 // should only be used for non-humongous allocations.
468 inline HeapWord* attempt_allocation(size_t min_word_size,
469 size_t desired_word_size,
470 size_t* actual_word_size);
471
472 // Second-level mutator allocation attempt: take the Heap_lock and
473 // retry the allocation attempt, potentially scheduling a GC
474 // pause. This should only be used for non-humongous allocations.
475 HeapWord* attempt_allocation_slow(size_t word_size);
476
477 // Takes the Heap_lock and attempts a humongous allocation. It can
478 // potentially schedule a GC pause.
479 HeapWord* attempt_allocation_humongous(size_t word_size);
480
481 // Allocation attempt that should be called during safepoints (e.g.,
482 // at the end of a successful GC). expect_null_mutator_alloc_region
483 // specifies whether the mutator alloc region is expected to be NULL
484 // or not.
485 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
486 bool expect_null_mutator_alloc_region);
487
488 // These methods are the "callbacks" from the G1AllocRegion class.
489
490 // For mutator alloc regions.
491 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force, uint node_index);
492 void retire_mutator_alloc_region(HeapRegion* alloc_region,
493 size_t allocated_bytes);
494
495 // For GC alloc regions.
496 bool has_more_regions(G1HeapRegionAttr dest);
497 HeapRegion* new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index);
498 void retire_gc_alloc_region(HeapRegion* alloc_region,
499 size_t allocated_bytes, G1HeapRegionAttr dest);
500
501 // - if explicit_gc is true, the GC is for a System.gc() etc,
502 // otherwise it's for a failed allocation.
503 // - if clear_all_soft_refs is true, all soft references should be
504 // cleared during the GC.
505 // - if do_maximum_compaction is true, full gc will do a maximally
506 // compacting collection, leaving no dead wood.
507 // - it returns false if it is unable to do the collection due to the
508 // GC locker being active, true otherwise.
509 bool do_full_collection(bool explicit_gc,
510 bool clear_all_soft_refs,
511 bool do_maximum_compaction);
512
513 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread.
514 virtual void do_full_collection(bool clear_all_soft_refs);
515
516 // Helper to do a full collection that clears soft references.
517 bool upgrade_to_full_collection();
518
519 // Callback from VM_G1CollectForAllocation operation.
520 // This function does everything necessary/possible to satisfy a
521 // failed allocation request (including collection, expansion, etc.)
522 HeapWord* satisfy_failed_allocation(size_t word_size,
523 bool* succeeded);
524 // Internal helpers used during full GC to split it up to
525 // increase readability.
526 void abort_concurrent_cycle();
527 void verify_before_full_collection(bool explicit_gc);
528 void prepare_heap_for_full_collection();
529 void prepare_heap_for_mutators();
530 void abort_refinement();
531 void verify_after_full_collection();
532 void print_heap_after_full_collection(G1HeapTransition* heap_transition);
533
534 // Helper method for satisfy_failed_allocation()
535 HeapWord* satisfy_failed_allocation_helper(size_t word_size,
536 bool do_gc,
537 bool maximum_compaction,
538 bool expect_null_mutator_alloc_region,
539 bool* gc_succeeded);
540
541 // Attempting to expand the heap sufficiently
542 // to support an allocation of the given "word_size". If
543 // successful, perform the allocation and return the address of the
544 // allocated block, or else "NULL".
545 HeapWord* expand_and_allocate(size_t word_size);
546
547 // Process any reference objects discovered.
548 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states);
549
550 // If during a concurrent start pause we may install a pending list head which is not
551 // otherwise reachable, ensure that it is marked in the bitmap for concurrent marking
552 // to discover.
553 void make_pending_list_reachable();
554
555 void verify_numa_regions(const char* desc);
556
557 public:
558 G1ServiceThread* service_thread() const { return _service_thread; }
559
560 WorkGang* workers() const { return _workers; }
561
562 // Runs the given AbstractGangTask with the current active workers,
563 // returning the total time taken.
564 Tickspan run_task_timed(AbstractGangTask* task);
565 // Run the given batch task using the work gang.
566 void run_batch_task(G1BatchedGangTask* cl);
567
568 G1Allocator* allocator() {
569 return _allocator;
570 }
571
572 G1HeapVerifier* verifier() {
573 return _verifier;
574 }
575
576 G1MonitoringSupport* g1mm() {
577 assert(_g1mm != NULL, "should have been initialized");
578 return _g1mm;
579 }
580
581 void resize_heap_if_necessary();
582
583 // Check if there is memory to uncommit and if so schedule a task to do it.
584 void uncommit_regions_if_necessary();
585 // Immediately uncommit uncommittable regions.
586 uint uncommit_regions(uint region_limit);
587 bool has_uncommittable_regions();
588
589 G1NUMA* numa() const { return _numa; }
590
591 // Expand the garbage-first heap by at least the given size (in bytes!).
592 // Returns true if the heap was expanded by the requested amount;
593 // false otherwise.
594 // (Rounds up to a HeapRegion boundary.)
595 bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL);
596 bool expand_single_region(uint node_index);
597
598 // Returns the PLAB statistics for a given destination.
599 inline G1EvacStats* alloc_buffer_stats(G1HeapRegionAttr dest);
600
601 // Determines PLAB size for a given destination.
602 inline size_t desired_plab_sz(G1HeapRegionAttr dest);
603
604 // Do anything common to GC's.
605 void gc_prologue(bool full);
606 void gc_epilogue(bool full);
607
608 // Does the given region fulfill remembered set based eager reclaim candidate requirements?
609 bool is_potential_eager_reclaim_candidate(HeapRegion* r) const;
610
611 // Modify the reclaim candidate set and test for presence.
612 // These are only valid for starts_humongous regions.
613 inline void set_humongous_reclaim_candidate(uint region, bool value);
614 inline bool is_humongous_reclaim_candidate(uint region);
615
616 // Remove from the reclaim candidate set. Also remove from the
617 // collection set so that later encounters avoid the slow path.
618 inline void set_humongous_is_live(oop obj);
619
620 // Register the given region to be part of the collection set.
621 inline void register_humongous_region_with_region_attr(uint index);
622
623 // We register a region with the fast "in collection set" test. We
624 // simply set to true the array slot corresponding to this region.
625 void register_young_region_with_region_attr(HeapRegion* r) {
626 _region_attr.set_in_young(r->hrm_index());
627 }
628 inline void register_region_with_region_attr(HeapRegion* r);
629 inline void register_old_region_with_region_attr(HeapRegion* r);
630 inline void register_optional_region_with_region_attr(HeapRegion* r);
631
632 void clear_region_attr(const HeapRegion* hr) {
633 _region_attr.clear(hr);
634 }
635
636 void clear_region_attr() {
637 _region_attr.clear();
638 }
639
640 // Verify that the G1RegionAttr remset tracking corresponds to actual remset tracking
641 // for all regions.
642 void verify_region_attr_remset_update() PRODUCT_RETURN;
643
644 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause);
645
646 // This is called at the start of either a concurrent cycle or a Full
647 // GC to update the number of old marking cycles started.
648 void increment_old_marking_cycles_started();
649
650 // This is called at the end of either a concurrent cycle or a Full
651 // GC to update the number of old marking cycles completed. Those two
652 // can happen in a nested fashion, i.e., we start a concurrent
653 // cycle, a Full GC happens half-way through it which ends first,
654 // and then the cycle notices that a Full GC happened and ends
655 // too. The concurrent parameter is a boolean to help us do a bit
656 // tighter consistency checking in the method. If concurrent is
657 // false, the caller is the inner caller in the nesting (i.e., the
658 // Full GC). If concurrent is true, the caller is the outer caller
659 // in this nesting (i.e., the concurrent cycle). Further nesting is
660 // not currently supported. The end of this call also notifies
661 // the G1OldGCCount_lock in case a Java thread is waiting for a full
662 // GC to happen (e.g., it called System.gc() with
663 // +ExplicitGCInvokesConcurrent).
664 // whole_heap_examined should indicate that during that old marking
665 // cycle the whole heap has been examined for live objects (as opposed
666 // to only parts, or aborted before completion).
667 void increment_old_marking_cycles_completed(bool concurrent, bool whole_heap_examined);
668
669 uint old_marking_cycles_completed() {
670 return _old_marking_cycles_completed;
671 }
672
673 G1HRPrinter* hr_printer() { return &_hr_printer; }
674
675 // Allocates a new heap region instance.
676 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr);
677
678 // Allocate the highest free region in the reserved heap. This will commit
679 // regions as necessary.
680 HeapRegion* alloc_highest_free_region();
681
682 // Frees a region by resetting its metadata and adding it to the free list
683 // passed as a parameter (this is usually a local list which will be appended
684 // to the master free list later or NULL if free list management is handled
685 // in another way).
686 // Callers must ensure they are the only one calling free on the given region
687 // at the same time.
688 void free_region(HeapRegion* hr, FreeRegionList* free_list);
689
690 // It dirties the cards that cover the block so that the post
691 // write barrier never queues anything when updating objects on this
692 // block. It is assumed (and in fact we assert) that the block
693 // belongs to a young region.
694 inline void dirty_young_block(HeapWord* start, size_t word_size);
695
696 // Frees a humongous region by collapsing it into individual regions
697 // and calling free_region() for each of them. The freed regions
698 // will be added to the free list that's passed as a parameter (this
699 // is usually a local list which will be appended to the master free
700 // list later).
701 // The method assumes that only a single thread is ever calling
702 // this for a particular region at once.
703 void free_humongous_region(HeapRegion* hr,
704 FreeRegionList* free_list);
705
706 // Facility for allocating in 'archive' regions in high heap memory and
707 // recording the allocated ranges. These should all be called from the
708 // VM thread at safepoints, without the heap lock held. They can be used
709 // to create and archive a set of heap regions which can be mapped at the
710 // same fixed addresses in a subsequent JVM invocation.
711 void begin_archive_alloc_range(bool open = false);
712
713 // Check if the requested size would be too large for an archive allocation.
714 bool is_archive_alloc_too_large(size_t word_size);
715
716 // Allocate memory of the requested size from the archive region. This will
717 // return NULL if the size is too large or if no memory is available. It
718 // does not trigger a garbage collection.
719 HeapWord* archive_mem_allocate(size_t word_size);
720
721 // Optionally aligns the end address and returns the allocated ranges in
722 // an array of MemRegions in order of ascending addresses.
723 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
724 size_t end_alignment_in_bytes = 0);
725
726 // Facility for allocating a fixed range within the heap and marking
727 // the containing regions as 'archive'. For use at JVM init time, when the
728 // caller may mmap archived heap data at the specified range(s).
729 // Verify that the MemRegions specified in the argument array are within the
730 // reserved heap.
731 bool check_archive_addresses(MemRegion* range, size_t count);
732
733 // Commit the appropriate G1 regions containing the specified MemRegions
734 // and mark them as 'archive' regions. The regions in the array must be
735 // non-overlapping and in order of ascending address.
736 bool alloc_archive_regions(MemRegion* range, size_t count, bool open);
737
738 // Insert any required filler objects in the G1 regions around the specified
739 // ranges to make the regions parseable. This must be called after
740 // alloc_archive_regions, and after class loading has occurred.
741 void fill_archive_regions(MemRegion* range, size_t count);
742
743 // Populate the G1BlockOffsetTablePart for archived regions with the given
744 // memory ranges.
745 void populate_archive_regions_bot_part(MemRegion* range, size_t count);
746
747 // For each of the specified MemRegions, uncommit the containing G1 regions
748 // which had been allocated by alloc_archive_regions. This should be called
749 // rather than fill_archive_regions at JVM init time if the archive file
750 // mapping failed, with the same non-overlapping and sorted MemRegion array.
751 void dealloc_archive_regions(MemRegion* range, size_t count);
752
753 private:
754
755 // Shrink the garbage-first heap by at most the given size (in bytes!).
756 // (Rounds down to a HeapRegion boundary.)
757 void shrink(size_t shrink_bytes);
758 void shrink_helper(size_t expand_bytes);
759
760 #if TASKQUEUE_STATS
761 static void print_taskqueue_stats_hdr(outputStream* const st);
762 void print_taskqueue_stats() const;
763 void reset_taskqueue_stats();
764 #endif // TASKQUEUE_STATS
765
766 // Start a concurrent cycle.
767 void start_concurrent_cycle(bool concurrent_operation_is_full_mark);
768
769 // Schedule the VM operation that will do an evacuation pause to
770 // satisfy an allocation request of word_size. *succeeded will
771 // return whether the VM operation was successful (it did do an
772 // evacuation pause) or not (another thread beat us to it or the GC
773 // locker was active). Given that we should not be holding the
774 // Heap_lock when we enter this method, we will pass the
775 // gc_count_before (i.e., total_collections()) as a parameter since
776 // it has to be read while holding the Heap_lock. Currently, both
777 // methods that call do_collection_pause() release the Heap_lock
778 // before the call, so it's easy to read gc_count_before just before.
779 HeapWord* do_collection_pause(size_t word_size,
780 uint gc_count_before,
781 bool* succeeded,
782 GCCause::Cause gc_cause);
783
784 void wait_for_root_region_scanning();
785
786 // Perform an incremental collection at a safepoint, possibly
787 // followed by a by-policy upgrade to a full collection. Returns
788 // false if unable to do the collection due to the GC locker being
789 // active, true otherwise.
790 // precondition: at safepoint on VM thread
791 // precondition: !is_gc_active()
792 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
793
794 // Helper for do_collection_pause_at_safepoint, containing the guts
795 // of the incremental collection pause, executed by the vm thread.
796 void do_collection_pause_at_safepoint_helper(double target_pause_time_ms);
797
798 G1HeapVerifier::G1VerifyType young_collection_verify_type() const;
799 void verify_before_young_collection(G1HeapVerifier::G1VerifyType type);
800 void verify_after_young_collection(G1HeapVerifier::G1VerifyType type);
801
802 void calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms);
803
804 // Actually do the work of evacuating the parts of the collection set.
805 // The has_optional_evacuation_work flag for the initial collection set
806 // evacuation indicates whether one or more optional evacuation steps may
807 // follow.
808 // If not set, G1 can avoid clearing the card tables of regions that we scan
809 // for roots from the heap: when scanning the card table for dirty cards after
810 // all remembered sets have been dumped onto it, for optional evacuation we
811 // mark these cards as "Scanned" to know that we do not need to re-scan them
812 // in the additional optional evacuation passes. This means that in the "Clear
813 // Card Table" phase we need to clear those marks. However, if there is no
814 // optional evacuation, g1 can immediately clean the dirty cards it encounters
815 // as nobody else will be looking at them again, saving the clear card table
816 // work later.
817 // This case is very common (young only collections and most mixed gcs), so
818 // depending on the ratio between scanned and evacuated regions (which g1 always
819 // needs to clear), this is a big win.
820 void evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states,
821 bool has_optional_evacuation_work);
822 void evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states);
823 private:
824 // Evacuate the next set of optional regions.
825 void evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states);
826
827 public:
828 void pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss);
829 void post_evacuate_collection_set(G1EvacuationInfo& evacuation_info,
830 G1RedirtyCardsQueueSet* rdcqs,
831 G1ParScanThreadStateSet* pss);
832
833 void expand_heap_after_young_collection();
834 // Update object copying statistics.
835 void record_obj_copy_mem_stats();
836
837 // The hot card cache for remembered set insertion optimization.
838 G1HotCardCache* _hot_card_cache;
839
840 // The g1 remembered set of the heap.
841 G1RemSet* _rem_set;
842
843 void post_evacuate_cleanup_1(G1ParScanThreadStateSet* per_thread_states,
844 G1RedirtyCardsQueueSet* rdcqs);
845 void post_evacuate_cleanup_2(PreservedMarksSet* preserved_marks,
846 G1RedirtyCardsQueueSet* rdcqs,
847 G1EvacuationInfo* evacuation_info,
848 const size_t* surviving_young_words);
849
850 // After a collection pause, reset eden and the collection set.
851 void clear_eden();
852 void clear_collection_set();
853
854 // Abandon the current collection set without recording policy
855 // statistics or updating free lists.
856 void abandon_collection_set(G1CollectionSet* collection_set);
857
858 // The concurrent marker (and the thread it runs in.)
859 G1ConcurrentMark* _cm;
860 G1ConcurrentMarkThread* _cm_thread;
861
862 // The concurrent refiner.
863 G1ConcurrentRefine* _cr;
864
865 // The parallel task queues
866 G1ScannerTasksQueueSet *_task_queues;
867
868 // Number of regions evacuation failed in the current collection.
869 volatile uint _num_regions_failed_evacuation;
870 // Records for every region on the heap whether evacuation failed for it.
871 volatile bool* _regions_failed_evacuation;
872
873 EvacuationFailedInfo* _evacuation_failed_info_array;
874
875 PreservedMarksSet _preserved_marks_set;
876
877 // Preserve the mark of "obj", if necessary, in preparation for its mark
878 // word being overwritten with a self-forwarding-pointer.
879 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m);
880
881 #ifndef PRODUCT
882 // Support for forcing evacuation failures. Analogous to
883 // PromotionFailureALot for the other collectors.
884
885 // Records whether G1EvacuationFailureALot should be in effect
886 // for the current GC
887 bool _evacuation_failure_alot_for_current_gc;
888
889 // Used to record the GC number for interval checking when
890 // determining whether G1EvaucationFailureALot is in effect
891 // for the current GC.
892 size_t _evacuation_failure_alot_gc_number;
893
894 // Count of the number of evacuations between failures.
895 volatile size_t _evacuation_failure_alot_count;
896
897 // Set whether G1EvacuationFailureALot should be in effect
898 // for the current GC (based upon the type of GC and which
899 // command line flags are set);
900 inline bool evacuation_failure_alot_for_gc_type(bool for_young_gc,
901 bool during_concurrent_start,
902 bool mark_or_rebuild_in_progress);
903
904 inline void set_evacuation_failure_alot_for_current_gc();
905
906 // Return true if it's time to cause an evacuation failure.
907 inline bool evacuation_should_fail();
908
909 // Reset the G1EvacuationFailureALot counters. Should be called at
910 // the end of an evacuation pause in which an evacuation failure occurred.
911 inline void reset_evacuation_should_fail();
912 #endif // !PRODUCT
913
914 // ("Weak") Reference processing support.
915 //
916 // G1 has 2 instances of the reference processor class. One
917 // (_ref_processor_cm) handles reference object discovery
918 // and subsequent processing during concurrent marking cycles.
919 //
920 // The other (_ref_processor_stw) handles reference object
921 // discovery and processing during full GCs and incremental
922 // evacuation pauses.
923 //
924 // During an incremental pause, reference discovery will be
925 // temporarily disabled for _ref_processor_cm and will be
926 // enabled for _ref_processor_stw. At the end of the evacuation
927 // pause references discovered by _ref_processor_stw will be
928 // processed and discovery will be disabled. The previous
929 // setting for reference object discovery for _ref_processor_cm
930 // will be re-instated.
931 //
932 // At the start of marking:
933 // * Discovery by the CM ref processor is verified to be inactive
934 // and it's discovered lists are empty.
935 // * Discovery by the CM ref processor is then enabled.
936 //
937 // At the end of marking:
938 // * Any references on the CM ref processor's discovered
939 // lists are processed (possibly MT).
940 //
941 // At the start of full GC we:
942 // * Disable discovery by the CM ref processor and
943 // empty CM ref processor's discovered lists
944 // (without processing any entries).
945 // * Verify that the STW ref processor is inactive and it's
946 // discovered lists are empty.
947 // * Temporarily set STW ref processor discovery as single threaded.
948 // * Temporarily clear the STW ref processor's _is_alive_non_header
949 // field.
950 // * Finally enable discovery by the STW ref processor.
951 //
952 // The STW ref processor is used to record any discovered
953 // references during the full GC.
954 //
955 // At the end of a full GC we:
956 // * Enqueue any reference objects discovered by the STW ref processor
957 // that have non-live referents. This has the side-effect of
958 // making the STW ref processor inactive by disabling discovery.
959 // * Verify that the CM ref processor is still inactive
960 // and no references have been placed on it's discovered
961 // lists (also checked as a precondition during concurrent start).
962
963 // The (stw) reference processor...
964 ReferenceProcessor* _ref_processor_stw;
965
966 // During reference object discovery, the _is_alive_non_header
967 // closure (if non-null) is applied to the referent object to
968 // determine whether the referent is live. If so then the
969 // reference object does not need to be 'discovered' and can
970 // be treated as a regular oop. This has the benefit of reducing
971 // the number of 'discovered' reference objects that need to
972 // be processed.
973 //
974 // Instance of the is_alive closure for embedding into the
975 // STW reference processor as the _is_alive_non_header field.
976 // Supplying a value for the _is_alive_non_header field is
977 // optional but doing so prevents unnecessary additions to
978 // the discovered lists during reference discovery.
979 G1STWIsAliveClosure _is_alive_closure_stw;
980
981 G1STWSubjectToDiscoveryClosure _is_subject_to_discovery_stw;
982
983 // The (concurrent marking) reference processor...
984 ReferenceProcessor* _ref_processor_cm;
985
986 // Instance of the concurrent mark is_alive closure for embedding
987 // into the Concurrent Marking reference processor as the
988 // _is_alive_non_header field. Supplying a value for the
989 // _is_alive_non_header field is optional but doing so prevents
990 // unnecessary additions to the discovered lists during reference
991 // discovery.
992 G1CMIsAliveClosure _is_alive_closure_cm;
993
994 G1CMSubjectToDiscoveryClosure _is_subject_to_discovery_cm;
995 public:
996
997 G1ScannerTasksQueue* task_queue(uint i) const;
998
999 uint num_task_queues() const;
1000
1001 // Create a G1CollectedHeap.
1002 // Must call the initialize method afterwards.
1003 // May not return if something goes wrong.
1004 G1CollectedHeap();
1005
1006 private:
1007 jint initialize_concurrent_refinement();
1008 jint initialize_service_thread();
1009 public:
1010 // Initialize the G1CollectedHeap to have the initial and
1011 // maximum sizes and remembered and barrier sets
1012 // specified by the policy object.
1013 jint initialize();
1014
1015 virtual void stop();
1016 virtual void safepoint_synchronize_begin();
1017 virtual void safepoint_synchronize_end();
1018
1019 // Does operations required after initialization has been done.
1020 void post_initialize();
1021
1022 // Initialize weak reference processing.
1023 void ref_processing_init();
1024
1025 virtual Name kind() const {
1026 return CollectedHeap::G1;
1027 }
1028
1029 virtual const char* name() const {
1030 return "G1";
1031 }
1032
1033 const G1CollectorState* collector_state() const { return &_collector_state; }
1034 G1CollectorState* collector_state() { return &_collector_state; }
1035
1036 // The current policy object for the collector.
1037 G1Policy* policy() const { return _policy; }
1038 // The remembered set.
1039 G1RemSet* rem_set() const { return _rem_set; }
1040
1041 inline G1GCPhaseTimes* phase_times() const;
1042
1043 const G1CollectionSet* collection_set() const { return &_collection_set; }
1044 G1CollectionSet* collection_set() { return &_collection_set; }
1045
1046 virtual SoftRefPolicy* soft_ref_policy();
1047
1048 virtual void initialize_serviceability();
1049 virtual MemoryUsage memory_usage();
1050 virtual GrowableArray<GCMemoryManager*> memory_managers();
1051 virtual GrowableArray<MemoryPool*> memory_pools();
1052
1053 // Try to minimize the remembered set.
1054 void scrub_rem_set();
1055
1056 // Apply the given closure on all cards in the Hot Card Cache, emptying it.
1057 void iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id);
1058
1059 // The shared block offset table array.
1060 G1BlockOffsetTable* bot() const { return _bot; }
1061
1062 // Reference Processing accessors
1063
1064 // The STW reference processor....
1065 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1066
1067 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; }
1068
1069 // The Concurrent Marking reference processor...
1070 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1071
1072 size_t unused_committed_regions_in_bytes() const;
1073
1074 virtual size_t capacity() const;
1075 virtual size_t used() const;
1076 // This should be called when we're not holding the heap lock. The
1077 // result might be a bit inaccurate.
1078 size_t used_unlocked() const;
1079 size_t recalculate_used() const;
1080
1081 // These virtual functions do the actual allocation.
1082 // Some heaps may offer a contiguous region for shared non-blocking
1083 // allocation, via inlined code (by exporting the address of the top and
1084 // end fields defining the extent of the contiguous allocation region.)
1085 // But G1CollectedHeap doesn't yet support this.
1086
1087 virtual bool is_maximal_no_gc() const {
1088 return _hrm.available() == 0;
1089 }
1090
1091 // Returns true if an incremental GC should be upgrade to a full gc. This
1092 // is done when there are no free regions and the heap can't be expanded.
1093 bool should_upgrade_to_full_gc() const {
1094 return is_maximal_no_gc() && num_free_regions() == 0;
1095 }
1096
1097 // The current number of regions in the heap.
1098 uint num_regions() const { return _hrm.length(); }
1099
1100 // The max number of regions reserved for the heap. Except for static array
1101 // sizing purposes you probably want to use max_regions().
1102 uint max_reserved_regions() const { return _hrm.reserved_length(); }
1103
1104 // Max number of regions that can be committed.
1105 uint max_regions() const { return _hrm.max_length(); }
1106
1107 // The number of regions that are completely free.
1108 uint num_free_regions() const { return _hrm.num_free_regions(); }
1109
1110 // The number of regions that can be allocated into.
1111 uint num_free_or_available_regions() const { return num_free_regions() + _hrm.available(); }
1112
1113 MemoryUsage get_auxiliary_data_memory_usage() const {
1114 return _hrm.get_auxiliary_data_memory_usage();
1115 }
1116
1117 // The number of regions that are not completely free.
1118 uint num_used_regions() const { return num_regions() - num_free_regions(); }
1119
1120 #ifdef ASSERT
1121 bool is_on_master_free_list(HeapRegion* hr) {
1122 return _hrm.is_free(hr);
1123 }
1124 #endif // ASSERT
1125
1126 inline void old_set_add(HeapRegion* hr);
1127 inline void old_set_remove(HeapRegion* hr);
1128
1129 inline void archive_set_add(HeapRegion* hr);
1130
1131 size_t non_young_capacity_bytes() {
1132 return (old_regions_count() + _archive_set.length() + humongous_regions_count()) * HeapRegion::GrainBytes;
1133 }
1134
1135 // Determine whether the given region is one that we are using as an
1136 // old GC alloc region.
1137 bool is_old_gc_alloc_region(HeapRegion* hr);
1138
1139 // Perform a collection of the heap; intended for use in implementing
1140 // "System.gc". This probably implies as full a collection as the
1141 // "CollectedHeap" supports.
1142 virtual void collect(GCCause::Cause cause);
1143
1144 // Perform a collection of the heap with the given cause.
1145 // Returns whether this collection actually executed.
1146 bool try_collect(GCCause::Cause cause);
1147
1148 // True iff an evacuation has failed in the most-recent collection.
1149 inline bool evacuation_failed() const;
1150 // True iff the given region encountered an evacuation failure in the most-recent
1151 // collection.
1152 inline bool evacuation_failed(uint region_idx) const;
1153
1154 inline uint num_regions_failed_evacuation() const;
1155 // Notify that the garbage collection encountered an evacuation failure in the
1156 // given region. Returns whether this has been the first occurrence of an evacuation
1157 // failure in that region.
1158 inline bool notify_region_failed_evacuation(uint const region_idx);
1159
1160 void remove_from_old_gen_sets(const uint old_regions_removed,
1161 const uint archive_regions_removed,
1162 const uint humongous_regions_removed);
1163 void prepend_to_freelist(FreeRegionList* list);
1164 void decrement_summary_bytes(size_t bytes);
1165
1166 virtual bool is_in(const void* p) const;
1167
1168 // Return "TRUE" iff the given object address is within the collection
1169 // set. Assumes that the reference points into the heap.
1170 inline bool is_in_cset(const HeapRegion *hr);
1171 inline bool is_in_cset(oop obj);
1172 inline bool is_in_cset(HeapWord* addr);
1173
1174 inline bool is_in_cset_or_humongous(const oop obj);
1175
1176 private:
1177 // This array is used for a quick test on whether a reference points into
1178 // the collection set or not. Each of the array's elements denotes whether the
1179 // corresponding region is in the collection set or not.
1180 G1HeapRegionAttrBiasedMappedArray _region_attr;
1181
1182 public:
1183
1184 inline G1HeapRegionAttr region_attr(const void* obj) const;
1185 inline G1HeapRegionAttr region_attr(uint idx) const;
1186
1187 MemRegion reserved() const {
1188 return _hrm.reserved();
1189 }
1190
1191 bool is_in_reserved(const void* addr) const {
1192 return reserved().contains(addr);
1193 }
1194
1195 G1HotCardCache* hot_card_cache() const { return _hot_card_cache; }
1196
1197 G1CardTable* card_table() const {
1198 return _card_table;
1199 }
1200
1201 // Iteration functions.
1202
1203 void object_iterate_parallel(ObjectClosure* cl, uint worker_id, HeapRegionClaimer* claimer);
1204
1205 // Iterate over all objects, calling "cl.do_object" on each.
1206 virtual void object_iterate(ObjectClosure* cl);
1207
1208 virtual ParallelObjectIterator* parallel_object_iterator(uint thread_num);
1209
1210 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
1211 virtual void keep_alive(oop obj);
1212
1213 // Iterate over heap regions, in address order, terminating the
1214 // iteration early if the "do_heap_region" method returns "true".
1215 void heap_region_iterate(HeapRegionClosure* blk) const;
1216
1217 // Return the region with the given index. It assumes the index is valid.
1218 inline HeapRegion* region_at(uint index) const;
1219 inline HeapRegion* region_at_or_null(uint index) const;
1220
1221 // Return the next region (by index) that is part of the same
1222 // humongous object that hr is part of.
1223 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const;
1224
1225 // Calculate the region index of the given address. Given address must be
1226 // within the heap.
1227 inline uint addr_to_region(HeapWord* addr) const;
1228
1229 inline HeapWord* bottom_addr_for_region(uint index) const;
1230
1231 // Two functions to iterate over the heap regions in parallel. Threads
1232 // compete using the HeapRegionClaimer to claim the regions before
1233 // applying the closure on them.
1234 // The _from_worker_offset version uses the HeapRegionClaimer and
1235 // the worker id to calculate a start offset to prevent all workers to
1236 // start from the point.
1237 void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
1238 HeapRegionClaimer* hrclaimer,
1239 uint worker_id) const;
1240
1241 void heap_region_par_iterate_from_start(HeapRegionClosure* cl,
1242 HeapRegionClaimer* hrclaimer) const;
1243
1244 // Iterate over all regions in the collection set in parallel.
1245 void collection_set_par_iterate_all(HeapRegionClosure* cl,
1246 HeapRegionClaimer* hr_claimer,
1247 uint worker_id);
1248
1249 // Iterate over all regions currently in the current collection set.
1250 void collection_set_iterate_all(HeapRegionClosure* blk);
1251
1252 // Iterate over the regions in the current increment of the collection set.
1253 // Starts the iteration so that the start regions of a given worker id over the
1254 // set active_workers are evenly spread across the set of collection set regions
1255 // to be iterated.
1256 // The variant with the HeapRegionClaimer guarantees that the closure will be
1257 // applied to a particular region exactly once.
1258 void collection_set_iterate_increment_from(HeapRegionClosure *blk, uint worker_id) {
1259 collection_set_iterate_increment_from(blk, NULL, worker_id);
1260 }
1261 void collection_set_iterate_increment_from(HeapRegionClosure *blk, HeapRegionClaimer* hr_claimer, uint worker_id);
1262
1263 // Returns the HeapRegion that contains addr. addr must not be NULL.
1264 template <class T>
1265 inline HeapRegion* heap_region_containing(const T addr) const;
1266
1267 // Returns the HeapRegion that contains addr, or NULL if that is an uncommitted
1268 // region. addr must not be NULL.
1269 template <class T>
1270 inline HeapRegion* heap_region_containing_or_null(const T addr) const;
1271
1272 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1273 // each address in the (reserved) heap is a member of exactly
1274 // one block. The defining characteristic of a block is that it is
1275 // possible to find its size, and thus to progress forward to the next
1276 // block. (Blocks may be of different sizes.) Thus, blocks may
1277 // represent Java objects, or they might be free blocks in a
1278 // free-list-based heap (or subheap), as long as the two kinds are
1279 // distinguishable and the size of each is determinable.
1280
1281 // Returns the address of the start of the "block" that contains the
1282 // address "addr". We say "blocks" instead of "object" since some heaps
1283 // may not pack objects densely; a chunk may either be an object or a
1284 // non-object.
1285 HeapWord* block_start(const void* addr) const;
1286
1287 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1288 // the block is an object.
1289 bool block_is_obj(const HeapWord* addr) const;
1290
1291 // Section on thread-local allocation buffers (TLABs)
1292 // See CollectedHeap for semantics.
1293
1294 size_t tlab_capacity(Thread* ignored) const;
1295 size_t tlab_used(Thread* ignored) const;
1296 size_t max_tlab_size() const;
1297 size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1298
1299 inline bool is_in_young(const oop obj);
1300
1301 // Returns "true" iff the given word_size is "very large".
1302 static bool is_humongous(size_t word_size) {
1303 // Note this has to be strictly greater-than as the TLABs
1304 // are capped at the humongous threshold and we want to
1305 // ensure that we don't try to allocate a TLAB as
1306 // humongous and that we don't allocate a humongous
1307 // object in a TLAB.
1308 return word_size > _humongous_object_threshold_in_words;
1309 }
1310
1311 // Returns the humongous threshold for a specific region size
1312 static size_t humongous_threshold_for(size_t region_size) {
1313 return (region_size / 2);
1314 }
1315
1316 // Returns the number of regions the humongous object of the given word size
1317 // requires.
1318 static size_t humongous_obj_size_in_regions(size_t word_size);
1319
1320 // Print the maximum heap capacity.
1321 virtual size_t max_capacity() const;
1322
1323 Tickspan time_since_last_collection() const { return Ticks::now() - _collection_pause_end; }
1324
1325 // Convenience function to be used in situations where the heap type can be
1326 // asserted to be this type.
1327 static G1CollectedHeap* heap() {
1328 return named_heap<G1CollectedHeap>(CollectedHeap::G1);
1329 }
1330
1331 void set_region_short_lived_locked(HeapRegion* hr);
1332 // add appropriate methods for any other surv rate groups
1333
1334 const G1SurvivorRegions* survivor() const { return &_survivor; }
1335
1336 uint eden_regions_count() const { return _eden.length(); }
1337 uint eden_regions_count(uint node_index) const { return _eden.regions_on_node(node_index); }
1338 uint survivor_regions_count() const { return _survivor.length(); }
1339 uint survivor_regions_count(uint node_index) const { return _survivor.regions_on_node(node_index); }
1340 size_t eden_regions_used_bytes() const { return _eden.used_bytes(); }
1341 size_t survivor_regions_used_bytes() const { return _survivor.used_bytes(); }
1342 uint young_regions_count() const { return _eden.length() + _survivor.length(); }
1343 uint old_regions_count() const { return _old_set.length(); }
1344 uint archive_regions_count() const { return _archive_set.length(); }
1345 uint humongous_regions_count() const { return _humongous_set.length(); }
1346
1347 #ifdef ASSERT
1348 bool check_young_list_empty();
1349 #endif
1350
1351 bool is_marked_next(oop obj) const;
1352
1353 // Determine if an object is dead, given the object and also
1354 // the region to which the object belongs.
1355 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1356 return hr->is_obj_dead(obj, _cm->prev_mark_bitmap());
1357 }
1358
1359 // This function returns true when an object has been
1360 // around since the previous marking and hasn't yet
1361 // been marked during this marking, and is not in a closed archive region.
1362 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1363 return
1364 !hr->obj_allocated_since_next_marking(obj) &&
1365 !is_marked_next(obj) &&
1366 !hr->is_closed_archive();
1367 }
1368
1369 // Determine if an object is dead, given only the object itself.
1370 // This will find the region to which the object belongs and
1371 // then call the region version of the same function.
1372
1373 // Added if it is NULL it isn't dead.
1374
1375 inline bool is_obj_dead(const oop obj) const;
1376
1377 inline bool is_obj_ill(const oop obj) const;
1378
1379 inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const;
1380 inline bool is_obj_dead_full(const oop obj) const;
1381
1382 G1ConcurrentMark* concurrent_mark() const { return _cm; }
1383
1384 // Refinement
1385
1386 G1ConcurrentRefine* concurrent_refine() const { return _cr; }
1387
1388 // Optimized nmethod scanning support routines
1389
1390 // Register the given nmethod with the G1 heap.
1391 virtual void register_nmethod(nmethod* nm);
1392
1393 // Unregister the given nmethod from the G1 heap.
1394 virtual void unregister_nmethod(nmethod* nm);
1395
1396 // No nmethod flushing needed.
1397 virtual void flush_nmethod(nmethod* nm) {}
1398
1399 // No nmethod verification implemented.
1400 virtual void verify_nmethod(nmethod* nm) {}
1401
1402 // Recalculate amount of used memory after GC. Must be called after all allocation
1403 // has finished.
1404 void update_used_after_gc();
1405 // Reset and re-enable the hot card cache.
1406 // Note the counts for the cards in the regions in the
1407 // collection set are reset when the collection set is freed.
1408 void reset_hot_card_cache();
1409 // Free up superfluous code root memory.
1410 void purge_code_root_memory();
1411
1412 // Rebuild the strong code root lists for each region
1413 // after a full GC.
1414 void rebuild_strong_code_roots();
1415
1416 // Performs cleaning of data structures after class unloading.
1417 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred);
1418
1419 // Verification
1420
1421 // Perform any cleanup actions necessary before allowing a verification.
1422 virtual void prepare_for_verify();
1423
1424 // Perform verification.
1425
1426 // vo == UsePrevMarking -> use "prev" marking information,
1427 // vo == UseNextMarking -> use "next" marking information
1428 // vo == UseFullMarking -> use "next" marking bitmap but no TAMS
1429 //
1430 // NOTE: Only the "prev" marking information is guaranteed to be
1431 // consistent most of the time, so most calls to this should use
1432 // vo == UsePrevMarking.
1433 // Currently, there is only one case where this is called with
1434 // vo == UseNextMarking, which is to verify the "next" marking
1435 // information at the end of remark.
1436 // Currently there is only one place where this is called with
1437 // vo == UseFullMarking, which is to verify the marking during a
1438 // full GC.
1439 void verify(VerifyOption vo);
1440
1441 // WhiteBox testing support.
1442 virtual bool supports_concurrent_gc_breakpoints() const;
1443
1444 virtual WorkGang* safepoint_workers() { return _workers; }
1445
1446 virtual bool is_archived_object(oop object) const;
1447
1448 // The methods below are here for convenience and dispatch the
1449 // appropriate method depending on value of the given VerifyOption
1450 // parameter. The values for that parameter, and their meanings,
1451 // are the same as those above.
1452
1453 bool is_obj_dead_cond(const oop obj,
1454 const HeapRegion* hr,
1455 const VerifyOption vo) const;
1456
1457 bool is_obj_dead_cond(const oop obj,
1458 const VerifyOption vo) const;
1459
1460 G1HeapSummary create_g1_heap_summary();
1461 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats);
1462
1463 // Printing
1464 private:
1465 void print_heap_regions() const;
1466 void print_regions_on(outputStream* st) const;
1467
1468 public:
1469 virtual void print_on(outputStream* st) const;
1470 virtual void print_extended_on(outputStream* st) const;
1471 virtual void print_on_error(outputStream* st) const;
1472
1473 virtual void gc_threads_do(ThreadClosure* tc) const;
1474
1475 // Override
1476 void print_tracing_info() const;
1477
1478 // The following two methods are helpful for debugging RSet issues.
1479 void print_cset_rsets() PRODUCT_RETURN;
1480 void print_all_rsets() PRODUCT_RETURN;
1481
1482 // Used to print information about locations in the hs_err file.
1483 virtual bool print_location(outputStream* st, void* addr) const;
1484 };
1485
1486 class G1ParEvacuateFollowersClosure : public VoidClosure {
1487 private:
1488 double _start_term;
1489 double _term_time;
1490 size_t _term_attempts;
1491
1492 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
1493 void end_term_time() { _term_time += (os::elapsedTime() - _start_term); }
1494 protected:
1495 G1CollectedHeap* _g1h;
1496 G1ParScanThreadState* _par_scan_state;
1497 G1ScannerTasksQueueSet* _queues;
1498 TaskTerminator* _terminator;
1499 G1GCPhaseTimes::GCParPhases _phase;
1500
1501 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
1502 G1ScannerTasksQueueSet* queues() { return _queues; }
1503 TaskTerminator* terminator() { return _terminator; }
1504
1505 public:
1506 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
1507 G1ParScanThreadState* par_scan_state,
1508 G1ScannerTasksQueueSet* queues,
1509 TaskTerminator* terminator,
1510 G1GCPhaseTimes::GCParPhases phase)
1511 : _start_term(0.0), _term_time(0.0), _term_attempts(0),
1512 _g1h(g1h), _par_scan_state(par_scan_state),
1513 _queues(queues), _terminator(terminator), _phase(phase) {}
1514
1515 void do_void();
1516
1517 double term_time() const { return _term_time; }
1518 size_t term_attempts() const { return _term_attempts; }
1519
1520 private:
1521 inline bool offer_termination();
1522 };
1523
1524 #endif // SHARE_GC_G1_G1COLLECTEDHEAP_HPP