1 /*
2 * Copyright (c) 2001, 2020, 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/g1HeapTransition.hpp"
40 #include "gc/g1/g1HeapVerifier.hpp"
41 #include "gc/g1/g1HRPrinter.hpp"
42 #include "gc/g1/g1HeapRegionAttr.hpp"
43 #include "gc/g1/g1MonitoringSupport.hpp"
44 #include "gc/g1/g1NUMA.hpp"
45 #include "gc/g1/g1RedirtyCardsQueue.hpp"
46 #include "gc/g1/g1SurvivorRegions.hpp"
47 #include "gc/g1/g1YCTypes.hpp"
48 #include "gc/g1/heapRegionManager.hpp"
49 #include "gc/g1/heapRegionSet.hpp"
50 #include "gc/g1/heterogeneousHeapRegionManager.hpp"
51 #include "gc/shared/barrierSet.hpp"
52 #include "gc/shared/collectedHeap.hpp"
53 #include "gc/shared/gcHeapSummary.hpp"
54 #include "gc/shared/plab.hpp"
55 #include "gc/shared/preservedMarks.hpp"
56 #include "gc/shared/softRefPolicy.hpp"
57 #include "gc/shared/taskqueue.hpp"
58 #include "memory/memRegion.hpp"
59 #include "utilities/stack.hpp"
60
61 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
62 // It uses the "Garbage First" heap organization and algorithm, which
63 // may combine concurrent marking with parallel, incremental compaction of
64 // heap subsets that will yield large amounts of garbage.
65
66 // Forward declarations
67 class HeapRegion;
68 class GenerationSpec;
69 class G1ParScanThreadState;
70 class G1ParScanThreadStateSet;
71 class G1ParScanThreadState;
72 class MemoryPool;
73 class MemoryManager;
74 class ObjectClosure;
75 class SpaceClosure;
76 class CompactibleSpaceClosure;
77 class Space;
78 class G1CardTableEntryClosure;
79 class G1CollectionSet;
80 class G1Policy;
81 class G1HotCardCache;
82 class G1RemSet;
83 class G1YoungRemSetSamplingThread;
84 class G1ConcurrentMark;
85 class G1ConcurrentMarkThread;
86 class G1ConcurrentRefine;
87 class GenerationCounters;
88 class STWGCTimer;
89 class G1NewTracer;
90 class EvacuationFailedInfo;
91 class nmethod;
92 class WorkGang;
93 class G1Allocator;
94 class G1ArchiveAllocator;
95 class G1FullGCScope;
96 class G1HeapVerifier;
97 class G1HeapSizingPolicy;
98 class G1HeapSummary;
99 class G1EvacSummary;
100
101 typedef OverflowTaskQueue<ScannerTask, mtGC> G1ScannerTasksQueue;
102 typedef GenericTaskQueueSet<G1ScannerTasksQueue, mtGC> G1ScannerTasksQueueSet;
103
104 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
105 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
106
107 // The G1 STW is alive closure.
108 // An instance is embedded into the G1CH and used as the
109 // (optional) _is_alive_non_header closure in the STW
110 // reference processor. It is also extensively used during
111 // reference processing during STW evacuation pauses.
112 class G1STWIsAliveClosure : public BoolObjectClosure {
113 G1CollectedHeap* _g1h;
114 public:
115 G1STWIsAliveClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
116 bool do_object_b(oop p);
117 };
118
119 class G1STWSubjectToDiscoveryClosure : public BoolObjectClosure {
120 G1CollectedHeap* _g1h;
121 public:
122 G1STWSubjectToDiscoveryClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
123 bool do_object_b(oop p);
124 };
125
126 class G1RegionMappingChangedListener : public G1MappingChangedListener {
127 private:
128 void reset_from_card_cache(uint start_idx, size_t num_regions);
129 public:
130 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
131 };
132
133 class G1CollectedHeap : public CollectedHeap {
134 friend class VM_CollectForMetadataAllocation;
135 friend class VM_G1CollectForAllocation;
136 friend class VM_G1CollectFull;
137 friend class VM_G1TryInitiateConcMark;
138 friend class VMStructs;
139 friend class MutatorAllocRegion;
140 friend class G1FullCollector;
141 friend class G1GCAllocRegion;
142 friend class G1HeapVerifier;
143
144 // Closures used in implementation.
145 friend class G1ParScanThreadState;
146 friend class G1ParScanThreadStateSet;
147 friend class G1EvacuateRegionsTask;
148 friend class G1PLABAllocator;
149
150 // Other related classes.
151 friend class HeapRegionClaimer;
152
153 // Testing classes.
154 friend class G1CheckRegionAttrTableClosure;
155
156 private:
157 G1YoungRemSetSamplingThread* _young_gen_sampling_thread;
158
159 WorkGang* _workers;
160 G1CardTable* _card_table;
161
162 Ticks _collection_pause_end;
163
164 SoftRefPolicy _soft_ref_policy;
165
166 static size_t _humongous_object_threshold_in_words;
167
168 // These sets keep track of old, archive and humongous regions respectively.
169 HeapRegionSet _old_set;
170 HeapRegionSet _archive_set;
171 HeapRegionSet _humongous_set;
172
173 void eagerly_reclaim_humongous_regions();
174 // Start a new incremental collection set for the next pause.
175 void start_new_collection_set();
176
177 // The block offset table for the G1 heap.
178 G1BlockOffsetTable* _bot;
179
180 // Tears down the region sets / lists so that they are empty and the
181 // regions on the heap do not belong to a region set / list. The
182 // only exception is the humongous set which we leave unaltered. If
183 // free_list_only is true, it will only tear down the master free
184 // list. It is called before a Full GC (free_list_only == false) or
185 // before heap shrinking (free_list_only == true).
186 void tear_down_region_sets(bool free_list_only);
187
188 // Rebuilds the region sets / lists so that they are repopulated to
189 // reflect the contents of the heap. The only exception is the
190 // humongous set which was not torn down in the first place. If
191 // free_list_only is true, it will only rebuild the master free
192 // list. It is called after a Full GC (free_list_only == false) or
193 // after heap shrinking (free_list_only == true).
194 void rebuild_region_sets(bool free_list_only);
195
196 // Callback for region mapping changed events.
197 G1RegionMappingChangedListener _listener;
198
199 // Handle G1 NUMA support.
200 G1NUMA* _numa;
201
202 // The sequence of all heap regions in the heap.
203 HeapRegionManager* _hrm;
204
205 // Manages all allocations with regions except humongous object allocations.
206 G1Allocator* _allocator;
207
208 // Manages all heap verification.
209 G1HeapVerifier* _verifier;
210
211 // Outside of GC pauses, the number of bytes used in all regions other
212 // than the current allocation region(s).
213 volatile size_t _summary_bytes_used;
214
215 void increase_used(size_t bytes);
216 void decrease_used(size_t bytes);
217
218 void set_used(size_t bytes);
219
220 // Number of bytes used in all regions during GC. Typically changed when
221 // retiring a GC alloc region.
222 size_t _bytes_used_during_gc;
223
224 // Class that handles archive allocation ranges.
225 G1ArchiveAllocator* _archive_allocator;
226
227 // GC allocation statistics policy for survivors.
228 G1EvacStats _survivor_evac_stats;
229
230 // GC allocation statistics policy for tenured objects.
231 G1EvacStats _old_evac_stats;
232
233 // It specifies whether we should attempt to expand the heap after a
234 // region allocation failure. If heap expansion fails we set this to
235 // false so that we don't re-attempt the heap expansion (it's likely
236 // that subsequent expansion attempts will also fail if one fails).
237 // Currently, it is only consulted during GC and it's reset at the
238 // start of each GC.
239 bool _expand_heap_after_alloc_failure;
240
241 // Helper for monitoring and management support.
242 G1MonitoringSupport* _g1mm;
243
244 // Records whether the region at the given index is (still) a
245 // candidate for eager reclaim. Only valid for humongous start
246 // regions; other regions have unspecified values. Humongous start
247 // regions are initialized at start of collection pause, with
248 // candidates removed from the set as they are found reachable from
249 // roots or the young generation.
250 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> {
251 protected:
252 bool default_value() const { return false; }
253 public:
254 void clear() { G1BiasedMappedArray<bool>::clear(); }
255 void set_candidate(uint region, bool value) {
256 set_by_index(region, value);
257 }
258 bool is_candidate(uint region) {
259 return get_by_index(region);
260 }
261 };
262
263 HumongousReclaimCandidates _humongous_reclaim_candidates;
264 // Stores whether during humongous object registration we found candidate regions.
265 // If not, we can skip a few steps.
266 bool _has_humongous_reclaim_candidates;
267
268 G1HRPrinter _hr_printer;
269
270 // Return true if an explicit GC should start a concurrent cycle instead
271 // of doing a STW full GC. A concurrent cycle should be started if:
272 // (a) cause == _g1_humongous_allocation,
273 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent,
274 // (c) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent,
275 // (d) cause == _wb_conc_mark or _wb_breakpoint,
276 // (e) cause == _g1_periodic_collection and +G1PeriodicGCInvokesConcurrent.
277 bool should_do_concurrent_full_gc(GCCause::Cause cause);
278
279 // Attempt to start a concurrent cycle with the indicated cause.
280 // precondition: should_do_concurrent_full_gc(cause)
281 bool try_collect_concurrently(GCCause::Cause cause,
282 uint gc_counter,
283 uint old_marking_started_before);
284
285 // Return true if should upgrade to full gc after an incremental one.
286 bool should_upgrade_to_full_gc(GCCause::Cause cause);
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 const char* young_gc_name() const;
387
388 // The young region list.
389 G1EdenRegions _eden;
390 G1SurvivorRegions _survivor;
391
392 STWGCTimer* _gc_timer_stw;
393
394 G1NewTracer* _gc_tracer_stw;
395
396 // The current policy object for the collector.
397 G1Policy* _policy;
398 G1HeapSizingPolicy* _heap_sizing_policy;
399
400 G1CollectionSet _collection_set;
401
402 // Try to allocate a single non-humongous HeapRegion sufficient for
403 // an allocation of the given word_size. If do_expand is true,
404 // attempt to expand the heap if necessary to satisfy the allocation
405 // request. 'type' takes the type of region to be allocated. (Use constants
406 // Old, Eden, Humongous, Survivor defined in HeapRegionType.)
407 HeapRegion* new_region(size_t word_size,
408 HeapRegionType type,
409 bool do_expand,
410 uint node_index = G1NUMA::AnyNodeIndex);
411
412 // Initialize a contiguous set of free regions of length num_regions
413 // and starting at index first so that they appear as a single
414 // humongous region.
415 HeapWord* humongous_obj_allocate_initialize_regions(HeapRegion* first_hr,
416 uint num_regions,
417 size_t word_size);
418
419 // Attempt to allocate a humongous object of the given size. Return
420 // NULL if unsuccessful.
421 HeapWord* humongous_obj_allocate(size_t word_size);
422
423 // The following two methods, allocate_new_tlab() and
424 // mem_allocate(), are the two main entry points from the runtime
425 // into the G1's allocation routines. They have the following
426 // assumptions:
427 //
428 // * They should both be called outside safepoints.
429 //
430 // * They should both be called without holding the Heap_lock.
431 //
432 // * All allocation requests for new TLABs should go to
433 // allocate_new_tlab().
434 //
435 // * All non-TLAB allocation requests should go to mem_allocate().
436 //
437 // * If either call cannot satisfy the allocation request using the
438 // current allocating region, they will try to get a new one. If
439 // this fails, they will attempt to do an evacuation pause and
440 // retry the allocation.
441 //
442 // * If all allocation attempts fail, even after trying to schedule
443 // an evacuation pause, allocate_new_tlab() will return NULL,
444 // whereas mem_allocate() will attempt a heap expansion and/or
445 // schedule a Full GC.
446 //
447 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
448 // should never be called with word_size being humongous. All
449 // humongous allocation requests should go to mem_allocate() which
450 // will satisfy them with a special path.
451
452 virtual HeapWord* allocate_new_tlab(size_t min_size,
453 size_t requested_size,
454 size_t* actual_size);
455
456 virtual HeapWord* mem_allocate(size_t word_size,
457 bool* gc_overhead_limit_was_exceeded);
458
459 // First-level mutator allocation attempt: try to allocate out of
460 // the mutator alloc region without taking the Heap_lock. This
461 // should only be used for non-humongous allocations.
462 inline HeapWord* attempt_allocation(size_t min_word_size,
463 size_t desired_word_size,
464 size_t* actual_word_size);
465
466 // Second-level mutator allocation attempt: take the Heap_lock and
467 // retry the allocation attempt, potentially scheduling a GC
468 // pause. This should only be used for non-humongous allocations.
469 HeapWord* attempt_allocation_slow(size_t word_size);
470
471 // Takes the Heap_lock and attempts a humongous allocation. It can
472 // potentially schedule a GC pause.
473 HeapWord* attempt_allocation_humongous(size_t word_size);
474
475 // Allocation attempt that should be called during safepoints (e.g.,
476 // at the end of a successful GC). expect_null_mutator_alloc_region
477 // specifies whether the mutator alloc region is expected to be NULL
478 // or not.
479 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
480 bool expect_null_mutator_alloc_region);
481
482 // These methods are the "callbacks" from the G1AllocRegion class.
483
484 // For mutator alloc regions.
485 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force, uint node_index);
486 void retire_mutator_alloc_region(HeapRegion* alloc_region,
487 size_t allocated_bytes);
488
489 // For GC alloc regions.
490 bool has_more_regions(G1HeapRegionAttr dest);
491 HeapRegion* new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index);
492 void retire_gc_alloc_region(HeapRegion* alloc_region,
493 size_t allocated_bytes, G1HeapRegionAttr dest);
494
495 // - if explicit_gc is true, the GC is for a System.gc() etc,
496 // otherwise it's for a failed allocation.
497 // - if clear_all_soft_refs is true, all soft references should be
498 // cleared during the GC.
499 // - it returns false if it is unable to do the collection due to the
500 // GC locker being active, true otherwise.
501 bool do_full_collection(bool explicit_gc,
502 bool clear_all_soft_refs);
503
504 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread.
505 virtual void do_full_collection(bool clear_all_soft_refs);
506
507 // Callback from VM_G1CollectForAllocation operation.
508 // This function does everything necessary/possible to satisfy a
509 // failed allocation request (including collection, expansion, etc.)
510 HeapWord* satisfy_failed_allocation(size_t word_size,
511 bool* succeeded);
512 // Internal helpers used during full GC to split it up to
513 // increase readability.
514 void abort_concurrent_cycle();
515 void verify_before_full_collection(bool explicit_gc);
516 void prepare_heap_for_full_collection();
517 void prepare_heap_for_mutators();
518 void abort_refinement();
519 void verify_after_full_collection();
520 void print_heap_after_full_collection(G1HeapTransition* heap_transition);
521
522 // Helper method for satisfy_failed_allocation()
523 HeapWord* satisfy_failed_allocation_helper(size_t word_size,
524 bool do_gc,
525 bool clear_all_soft_refs,
526 bool expect_null_mutator_alloc_region,
527 bool* gc_succeeded);
528
529 // Attempting to expand the heap sufficiently
530 // to support an allocation of the given "word_size". If
531 // successful, perform the allocation and return the address of the
532 // allocated block, or else "NULL".
533 HeapWord* expand_and_allocate(size_t word_size);
534
535 // Process any reference objects discovered.
536 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states);
537
538 // If during a concurrent start pause we may install a pending list head which is not
539 // otherwise reachable, ensure that it is marked in the bitmap for concurrent marking
540 // to discover.
541 void make_pending_list_reachable();
542
543 // Merges the information gathered on a per-thread basis for all worker threads
544 // during GC into global variables.
545 void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states);
546
547 void verify_numa_regions(const char* desc);
548
549 public:
550 G1YoungRemSetSamplingThread* sampling_thread() const { return _young_gen_sampling_thread; }
551
552 WorkGang* workers() const { return _workers; }
553
554 // Runs the given AbstractGangTask with the current active workers.
555 virtual void run_task(AbstractGangTask* task);
556
557 // Runs the given AbstractGangTask with the current active workers,
558 // returning the total time taken.
559 Tickspan run_task_timed(AbstractGangTask* task);
560
561 G1Allocator* allocator() {
562 return _allocator;
563 }
564
565 G1HeapVerifier* verifier() {
566 return _verifier;
567 }
568
569 G1MonitoringSupport* g1mm() {
570 assert(_g1mm != NULL, "should have been initialized");
571 return _g1mm;
572 }
573
574 void resize_heap_if_necessary();
575
576 G1NUMA* numa() const { return _numa; }
577
578 // Expand the garbage-first heap by at least the given size (in bytes!).
579 // Returns true if the heap was expanded by the requested amount;
580 // false otherwise.
581 // (Rounds up to a HeapRegion boundary.)
582 bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL);
583 bool expand_single_region(uint node_index);
584
585 // Returns the PLAB statistics for a given destination.
586 inline G1EvacStats* alloc_buffer_stats(G1HeapRegionAttr dest);
587
588 // Determines PLAB size for a given destination.
589 inline size_t desired_plab_sz(G1HeapRegionAttr dest);
590
591 // Do anything common to GC's.
592 void gc_prologue(bool full);
593 void gc_epilogue(bool full);
594
595 // Does the given region fulfill remembered set based eager reclaim candidate requirements?
596 bool is_potential_eager_reclaim_candidate(HeapRegion* r) const;
597
598 // Modify the reclaim candidate set and test for presence.
599 // These are only valid for starts_humongous regions.
600 inline void set_humongous_reclaim_candidate(uint region, bool value);
601 inline bool is_humongous_reclaim_candidate(uint region);
602 inline void set_has_humongous_reclaim_candidate(bool value);
603
604 // Remove from the reclaim candidate set. Also remove from the
605 // collection set so that later encounters avoid the slow path.
606 inline void set_humongous_is_live(oop obj);
607
608 // Register the given region to be part of the collection set.
609 inline void register_humongous_region_with_region_attr(uint index);
610
611 // We register a region with the fast "in collection set" test. We
612 // simply set to true the array slot corresponding to this region.
613 void register_young_region_with_region_attr(HeapRegion* r) {
614 _region_attr.set_in_young(r->hrm_index());
615 }
616 inline void register_region_with_region_attr(HeapRegion* r);
617 inline void register_old_region_with_region_attr(HeapRegion* r);
618 inline void register_optional_region_with_region_attr(HeapRegion* r);
619
620 void clear_region_attr(const HeapRegion* hr) {
621 _region_attr.clear(hr);
622 }
623
624 void clear_region_attr() {
625 _region_attr.clear();
626 }
627
628 // Verify that the G1RegionAttr remset tracking corresponds to actual remset tracking
629 // for all regions.
630 void verify_region_attr_remset_update() PRODUCT_RETURN;
631
632 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause);
633
634 // This is called at the start of either a concurrent cycle or a Full
635 // GC to update the number of old marking cycles started.
636 void increment_old_marking_cycles_started();
637
638 // This is called at the end of either a concurrent cycle or a Full
639 // GC to update the number of old marking cycles completed. Those two
640 // can happen in a nested fashion, i.e., we start a concurrent
641 // cycle, a Full GC happens half-way through it which ends first,
642 // and then the cycle notices that a Full GC happened and ends
643 // too. The concurrent parameter is a boolean to help us do a bit
644 // tighter consistency checking in the method. If concurrent is
645 // false, the caller is the inner caller in the nesting (i.e., the
646 // Full GC). If concurrent is true, the caller is the outer caller
647 // in this nesting (i.e., the concurrent cycle). Further nesting is
648 // not currently supported. The end of this call also notifies
649 // the G1OldGCCount_lock in case a Java thread is waiting for a full
650 // GC to happen (e.g., it called System.gc() with
651 // +ExplicitGCInvokesConcurrent).
652 // whole_heap_examined should indicate that during that old marking
653 // cycle the whole heap has been examined for live objects (as opposed
654 // to only parts, or aborted before completion).
655 void increment_old_marking_cycles_completed(bool concurrent, bool whole_heap_examined);
656
657 uint old_marking_cycles_completed() {
658 return _old_marking_cycles_completed;
659 }
660
661 G1HRPrinter* hr_printer() { return &_hr_printer; }
662
663 // Allocates a new heap region instance.
664 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr);
665
666 // Allocate the highest free region in the reserved heap. This will commit
667 // regions as necessary.
668 HeapRegion* alloc_highest_free_region();
669
670 // Frees a region by resetting its metadata and adding it to the free list
671 // passed as a parameter (this is usually a local list which will be appended
672 // to the master free list later or NULL if free list management is handled
673 // in another way).
674 // Callers must ensure they are the only one calling free on the given region
675 // at the same time.
676 void free_region(HeapRegion* hr, FreeRegionList* free_list);
677
678 // It dirties the cards that cover the block so that the post
679 // write barrier never queues anything when updating objects on this
680 // block. It is assumed (and in fact we assert) that the block
681 // belongs to a young region.
682 inline void dirty_young_block(HeapWord* start, size_t word_size);
683
684 // Frees a humongous region by collapsing it into individual regions
685 // and calling free_region() for each of them. The freed regions
686 // will be added to the free list that's passed as a parameter (this
687 // is usually a local list which will be appended to the master free
688 // list later).
689 // The method assumes that only a single thread is ever calling
690 // this for a particular region at once.
691 void free_humongous_region(HeapRegion* hr,
692 FreeRegionList* free_list);
693
694 // Facility for allocating in 'archive' regions in high heap memory and
695 // recording the allocated ranges. These should all be called from the
696 // VM thread at safepoints, without the heap lock held. They can be used
697 // to create and archive a set of heap regions which can be mapped at the
698 // same fixed addresses in a subsequent JVM invocation.
699 void begin_archive_alloc_range(bool open = false);
700
701 // Check if the requested size would be too large for an archive allocation.
702 bool is_archive_alloc_too_large(size_t word_size);
703
704 // Allocate memory of the requested size from the archive region. This will
705 // return NULL if the size is too large or if no memory is available. It
706 // does not trigger a garbage collection.
707 HeapWord* archive_mem_allocate(size_t word_size);
708
709 // Optionally aligns the end address and returns the allocated ranges in
710 // an array of MemRegions in order of ascending addresses.
711 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
712 size_t end_alignment_in_bytes = 0);
713
714 // Facility for allocating a fixed range within the heap and marking
715 // the containing regions as 'archive'. For use at JVM init time, when the
716 // caller may mmap archived heap data at the specified range(s).
717 // Verify that the MemRegions specified in the argument array are within the
718 // reserved heap.
719 bool check_archive_addresses(MemRegion* range, size_t count);
720
721 // Commit the appropriate G1 regions containing the specified MemRegions
722 // and mark them as 'archive' regions. The regions in the array must be
723 // non-overlapping and in order of ascending address.
724 bool alloc_archive_regions(MemRegion* range, size_t count, bool open);
725
726 // Insert any required filler objects in the G1 regions around the specified
727 // ranges to make the regions parseable. This must be called after
728 // alloc_archive_regions, and after class loading has occurred.
729 void fill_archive_regions(MemRegion* range, size_t count);
730
731 // For each of the specified MemRegions, uncommit the containing G1 regions
732 // which had been allocated by alloc_archive_regions. This should be called
733 // rather than fill_archive_regions at JVM init time if the archive file
734 // mapping failed, with the same non-overlapping and sorted MemRegion array.
735 void dealloc_archive_regions(MemRegion* range, size_t count);
736
737 oop materialize_archived_object(oop obj);
738
739 private:
740
741 // Shrink the garbage-first heap by at most the given size (in bytes!).
742 // (Rounds down to a HeapRegion boundary.)
743 void shrink(size_t shrink_bytes);
744 void shrink_helper(size_t expand_bytes);
745
746 #if TASKQUEUE_STATS
747 static void print_taskqueue_stats_hdr(outputStream* const st);
748 void print_taskqueue_stats() const;
749 void reset_taskqueue_stats();
750 #endif // TASKQUEUE_STATS
751
752 // Schedule the VM operation that will do an evacuation pause to
753 // satisfy an allocation request of word_size. *succeeded will
754 // return whether the VM operation was successful (it did do an
755 // evacuation pause) or not (another thread beat us to it or the GC
756 // locker was active). Given that we should not be holding the
757 // Heap_lock when we enter this method, we will pass the
758 // gc_count_before (i.e., total_collections()) as a parameter since
759 // it has to be read while holding the Heap_lock. Currently, both
760 // methods that call do_collection_pause() release the Heap_lock
761 // before the call, so it's easy to read gc_count_before just before.
762 HeapWord* do_collection_pause(size_t word_size,
763 uint gc_count_before,
764 bool* succeeded,
765 GCCause::Cause gc_cause);
766
767 void wait_for_root_region_scanning();
768
769 // Perform an incremental collection at a safepoint, possibly
770 // followed by a by-policy upgrade to a full collection. Returns
771 // false if unable to do the collection due to the GC locker being
772 // active, true otherwise.
773 // precondition: at safepoint on VM thread
774 // precondition: !is_gc_active()
775 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
776
777 // Helper for do_collection_pause_at_safepoint, containing the guts
778 // of the incremental collection pause, executed by the vm thread.
779 void do_collection_pause_at_safepoint_helper(double target_pause_time_ms);
780
781 G1HeapVerifier::G1VerifyType young_collection_verify_type() const;
782 void verify_before_young_collection(G1HeapVerifier::G1VerifyType type);
783 void verify_after_young_collection(G1HeapVerifier::G1VerifyType type);
784
785 void calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms);
786
787 // Actually do the work of evacuating the parts of the collection set.
788 void evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states);
789 void evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states);
790 private:
791 // Evacuate the next set of optional regions.
792 void evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states);
793
794 public:
795 void pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss);
796 void post_evacuate_collection_set(G1EvacuationInfo& evacuation_info,
797 G1RedirtyCardsQueueSet* rdcqs,
798 G1ParScanThreadStateSet* pss);
799
800 void expand_heap_after_young_collection();
801 // Update object copying statistics.
802 void record_obj_copy_mem_stats();
803
804 // The hot card cache for remembered set insertion optimization.
805 G1HotCardCache* _hot_card_cache;
806
807 // The g1 remembered set of the heap.
808 G1RemSet* _rem_set;
809
810 // After a collection pause, convert the regions in the collection set into free
811 // regions.
812 void free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words);
813
814 // Abandon the current collection set without recording policy
815 // statistics or updating free lists.
816 void abandon_collection_set(G1CollectionSet* collection_set);
817
818 // The concurrent marker (and the thread it runs in.)
819 G1ConcurrentMark* _cm;
820 G1ConcurrentMarkThread* _cm_thread;
821
822 // The concurrent refiner.
823 G1ConcurrentRefine* _cr;
824
825 // The parallel task queues
826 G1ScannerTasksQueueSet *_task_queues;
827
828 // True iff a evacuation has failed in the current collection.
829 bool _evacuation_failed;
830
831 EvacuationFailedInfo* _evacuation_failed_info_array;
832
833 // Failed evacuations cause some logical from-space objects to have
834 // forwarding pointers to themselves. Reset them.
835 void remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs);
836
837 // Restore the objects in the regions in the collection set after an
838 // evacuation failure.
839 void restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs);
840
841 PreservedMarksSet _preserved_marks_set;
842
843 // Preserve the mark of "obj", if necessary, in preparation for its mark
844 // word being overwritten with a self-forwarding-pointer.
845 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m);
846
847 #ifndef PRODUCT
848 // Support for forcing evacuation failures. Analogous to
849 // PromotionFailureALot for the other collectors.
850
851 // Records whether G1EvacuationFailureALot should be in effect
852 // for the current GC
853 bool _evacuation_failure_alot_for_current_gc;
854
855 // Used to record the GC number for interval checking when
856 // determining whether G1EvaucationFailureALot is in effect
857 // for the current GC.
858 size_t _evacuation_failure_alot_gc_number;
859
860 // Count of the number of evacuations between failures.
861 volatile size_t _evacuation_failure_alot_count;
862
863 // Set whether G1EvacuationFailureALot should be in effect
864 // for the current GC (based upon the type of GC and which
865 // command line flags are set);
866 inline bool evacuation_failure_alot_for_gc_type(bool for_young_gc,
867 bool during_concurrent_start,
868 bool mark_or_rebuild_in_progress);
869
870 inline void set_evacuation_failure_alot_for_current_gc();
871
872 // Return true if it's time to cause an evacuation failure.
873 inline bool evacuation_should_fail();
874
875 // Reset the G1EvacuationFailureALot counters. Should be called at
876 // the end of an evacuation pause in which an evacuation failure occurred.
877 inline void reset_evacuation_should_fail();
878 #endif // !PRODUCT
879
880 // ("Weak") Reference processing support.
881 //
882 // G1 has 2 instances of the reference processor class. One
883 // (_ref_processor_cm) handles reference object discovery
884 // and subsequent processing during concurrent marking cycles.
885 //
886 // The other (_ref_processor_stw) handles reference object
887 // discovery and processing during full GCs and incremental
888 // evacuation pauses.
889 //
890 // During an incremental pause, reference discovery will be
891 // temporarily disabled for _ref_processor_cm and will be
892 // enabled for _ref_processor_stw. At the end of the evacuation
893 // pause references discovered by _ref_processor_stw will be
894 // processed and discovery will be disabled. The previous
895 // setting for reference object discovery for _ref_processor_cm
896 // will be re-instated.
897 //
898 // At the start of marking:
899 // * Discovery by the CM ref processor is verified to be inactive
900 // and it's discovered lists are empty.
901 // * Discovery by the CM ref processor is then enabled.
902 //
903 // At the end of marking:
904 // * Any references on the CM ref processor's discovered
905 // lists are processed (possibly MT).
906 //
907 // At the start of full GC we:
908 // * Disable discovery by the CM ref processor and
909 // empty CM ref processor's discovered lists
910 // (without processing any entries).
911 // * Verify that the STW ref processor is inactive and it's
912 // discovered lists are empty.
913 // * Temporarily set STW ref processor discovery as single threaded.
914 // * Temporarily clear the STW ref processor's _is_alive_non_header
915 // field.
916 // * Finally enable discovery by the STW ref processor.
917 //
918 // The STW ref processor is used to record any discovered
919 // references during the full GC.
920 //
921 // At the end of a full GC we:
922 // * Enqueue any reference objects discovered by the STW ref processor
923 // that have non-live referents. This has the side-effect of
924 // making the STW ref processor inactive by disabling discovery.
925 // * Verify that the CM ref processor is still inactive
926 // and no references have been placed on it's discovered
927 // lists (also checked as a precondition during concurrent start).
928
929 // The (stw) reference processor...
930 ReferenceProcessor* _ref_processor_stw;
931
932 // During reference object discovery, the _is_alive_non_header
933 // closure (if non-null) is applied to the referent object to
934 // determine whether the referent is live. If so then the
935 // reference object does not need to be 'discovered' and can
936 // be treated as a regular oop. This has the benefit of reducing
937 // the number of 'discovered' reference objects that need to
938 // be processed.
939 //
940 // Instance of the is_alive closure for embedding into the
941 // STW reference processor as the _is_alive_non_header field.
942 // Supplying a value for the _is_alive_non_header field is
943 // optional but doing so prevents unnecessary additions to
944 // the discovered lists during reference discovery.
945 G1STWIsAliveClosure _is_alive_closure_stw;
946
947 G1STWSubjectToDiscoveryClosure _is_subject_to_discovery_stw;
948
949 // The (concurrent marking) reference processor...
950 ReferenceProcessor* _ref_processor_cm;
951
952 // Instance of the concurrent mark is_alive closure for embedding
953 // into the Concurrent Marking reference processor as the
954 // _is_alive_non_header field. Supplying a value for the
955 // _is_alive_non_header field is optional but doing so prevents
956 // unnecessary additions to the discovered lists during reference
957 // discovery.
958 G1CMIsAliveClosure _is_alive_closure_cm;
959
960 G1CMSubjectToDiscoveryClosure _is_subject_to_discovery_cm;
961 public:
962
963 G1ScannerTasksQueue* task_queue(uint i) const;
964
965 uint num_task_queues() const;
966
967 // Create a G1CollectedHeap.
968 // Must call the initialize method afterwards.
969 // May not return if something goes wrong.
970 G1CollectedHeap();
971
972 private:
973 jint initialize_concurrent_refinement();
974 jint initialize_young_gen_sampling_thread();
975 public:
976 // Initialize the G1CollectedHeap to have the initial and
977 // maximum sizes and remembered and barrier sets
978 // specified by the policy object.
979 jint initialize();
980
981 virtual void stop();
982 virtual void safepoint_synchronize_begin();
983 virtual void safepoint_synchronize_end();
984
985 // Does operations required after initialization has been done.
986 void post_initialize();
987
988 // Initialize weak reference processing.
989 void ref_processing_init();
990
991 virtual Name kind() const {
992 return CollectedHeap::G1;
993 }
994
995 virtual const char* name() const {
996 return "G1";
997 }
998
999 const G1CollectorState* collector_state() const { return &_collector_state; }
1000 G1CollectorState* collector_state() { return &_collector_state; }
1001
1002 // The current policy object for the collector.
1003 G1Policy* policy() const { return _policy; }
1004 // The remembered set.
1005 G1RemSet* rem_set() const { return _rem_set; }
1006
1007 inline G1GCPhaseTimes* phase_times() const;
1008
1009 HeapRegionManager* hrm() const { return _hrm; }
1010
1011 const G1CollectionSet* collection_set() const { return &_collection_set; }
1012 G1CollectionSet* collection_set() { return &_collection_set; }
1013
1014 virtual SoftRefPolicy* soft_ref_policy();
1015
1016 virtual void initialize_serviceability();
1017 virtual MemoryUsage memory_usage();
1018 virtual GrowableArray<GCMemoryManager*> memory_managers();
1019 virtual GrowableArray<MemoryPool*> memory_pools();
1020
1021 // Try to minimize the remembered set.
1022 void scrub_rem_set();
1023
1024 // Apply the given closure on all cards in the Hot Card Cache, emptying it.
1025 void iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id);
1026
1027 // The shared block offset table array.
1028 G1BlockOffsetTable* bot() const { return _bot; }
1029
1030 // Reference Processing accessors
1031
1032 // The STW reference processor....
1033 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1034
1035 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; }
1036
1037 // The Concurrent Marking reference processor...
1038 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1039
1040 size_t unused_committed_regions_in_bytes() const;
1041
1042 virtual size_t capacity() const;
1043 virtual size_t used() const;
1044 // This should be called when we're not holding the heap lock. The
1045 // result might be a bit inaccurate.
1046 size_t used_unlocked() const;
1047 size_t recalculate_used() const;
1048
1049 // These virtual functions do the actual allocation.
1050 // Some heaps may offer a contiguous region for shared non-blocking
1051 // allocation, via inlined code (by exporting the address of the top and
1052 // end fields defining the extent of the contiguous allocation region.)
1053 // But G1CollectedHeap doesn't yet support this.
1054
1055 virtual bool is_maximal_no_gc() const {
1056 return _hrm->available() == 0;
1057 }
1058
1059 // Returns whether there are any regions left in the heap for allocation.
1060 bool has_regions_left_for_allocation() const {
1061 return !is_maximal_no_gc() || num_free_regions() != 0;
1062 }
1063
1064 // The current number of regions in the heap.
1065 uint num_regions() const { return _hrm->length(); }
1066
1067 // The max number of regions in the heap.
1068 uint max_regions() const { return _hrm->max_length(); }
1069
1070 // Max number of regions that can be comitted.
1071 uint max_expandable_regions() const { return _hrm->max_expandable_length(); }
1072
1073 // The number of regions that are completely free.
1074 uint num_free_regions() const { return _hrm->num_free_regions(); }
1075
1076 // The number of regions that can be allocated into.
1077 uint num_free_or_available_regions() const { return num_free_regions() + _hrm->available(); }
1078
1079 MemoryUsage get_auxiliary_data_memory_usage() const {
1080 return _hrm->get_auxiliary_data_memory_usage();
1081 }
1082
1083 // The number of regions that are not completely free.
1084 uint num_used_regions() const { return num_regions() - num_free_regions(); }
1085
1086 #ifdef ASSERT
1087 bool is_on_master_free_list(HeapRegion* hr) {
1088 return _hrm->is_free(hr);
1089 }
1090 #endif // ASSERT
1091
1092 inline void old_set_add(HeapRegion* hr);
1093 inline void old_set_remove(HeapRegion* hr);
1094
1095 inline void archive_set_add(HeapRegion* hr);
1096
1097 size_t non_young_capacity_bytes() {
1098 return (old_regions_count() + _archive_set.length() + humongous_regions_count()) * HeapRegion::GrainBytes;
1099 }
1100
1101 // Determine whether the given region is one that we are using as an
1102 // old GC alloc region.
1103 bool is_old_gc_alloc_region(HeapRegion* hr);
1104
1105 // Perform a collection of the heap; intended for use in implementing
1106 // "System.gc". This probably implies as full a collection as the
1107 // "CollectedHeap" supports.
1108 virtual void collect(GCCause::Cause cause);
1109
1110 // Perform a collection of the heap with the given cause.
1111 // Returns whether this collection actually executed.
1112 bool try_collect(GCCause::Cause cause);
1113
1114 // True iff an evacuation has failed in the most-recent collection.
1115 bool evacuation_failed() { return _evacuation_failed; }
1116
1117 void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed);
1118 void prepend_to_freelist(FreeRegionList* list);
1119 void decrement_summary_bytes(size_t bytes);
1120
1121 virtual bool is_in(const void* p) const;
1122 #ifdef ASSERT
1123 // Returns whether p is in one of the available areas of the heap. Slow but
1124 // extensive version.
1125 bool is_in_exact(const void* p) const;
1126 #endif
1127
1128 // Return "TRUE" iff the given object address is within the collection
1129 // set. Assumes that the reference points into the heap.
1130 inline bool is_in_cset(const HeapRegion *hr);
1131 inline bool is_in_cset(oop obj);
1132 inline bool is_in_cset(HeapWord* addr);
1133
1134 inline bool is_in_cset_or_humongous(const oop obj);
1135
1136 private:
1137 // This array is used for a quick test on whether a reference points into
1138 // the collection set or not. Each of the array's elements denotes whether the
1139 // corresponding region is in the collection set or not.
1140 G1HeapRegionAttrBiasedMappedArray _region_attr;
1141
1142 public:
1143
1144 inline G1HeapRegionAttr region_attr(const void* obj) const;
1145 inline G1HeapRegionAttr region_attr(uint idx) const;
1146
1147 // Return "TRUE" iff the given object address is in the reserved
1148 // region of g1.
1149 bool is_in_g1_reserved(const void* p) const {
1150 return _hrm->reserved().contains(p);
1151 }
1152
1153 // Returns a MemRegion that corresponds to the space that has been
1154 // reserved for the heap
1155 MemRegion g1_reserved() const {
1156 return _hrm->reserved();
1157 }
1158
1159 MemRegion reserved_region() const {
1160 return _reserved;
1161 }
1162
1163 HeapWord* base() const {
1164 return _reserved.start();
1165 }
1166
1167 bool is_in_reserved(const void* addr) const {
1168 return _reserved.contains(addr);
1169 }
1170
1171 G1HotCardCache* hot_card_cache() const { return _hot_card_cache; }
1172
1173 G1CardTable* card_table() const {
1174 return _card_table;
1175 }
1176
1177 // Iteration functions.
1178
1179 void object_iterate_parallel(ObjectClosure* cl, uint worker_id, HeapRegionClaimer* claimer);
1180
1181 // Iterate over all objects, calling "cl.do_object" on each.
1182 virtual void object_iterate(ObjectClosure* cl);
1183
1184 virtual ParallelObjectIterator* parallel_object_iterator(uint thread_num);
1185
1186 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
1187 virtual void keep_alive(oop obj);
1188
1189 // Iterate over heap regions, in address order, terminating the
1190 // iteration early if the "do_heap_region" method returns "true".
1191 void heap_region_iterate(HeapRegionClosure* blk) const;
1192
1193 // Return the region with the given index. It assumes the index is valid.
1194 inline HeapRegion* region_at(uint index) const;
1195 inline HeapRegion* region_at_or_null(uint index) const;
1196
1197 // Return the next region (by index) that is part of the same
1198 // humongous object that hr is part of.
1199 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const;
1200
1201 // Calculate the region index of the given address. Given address must be
1202 // within the heap.
1203 inline uint addr_to_region(HeapWord* addr) const;
1204
1205 inline HeapWord* bottom_addr_for_region(uint index) const;
1206
1207 // Two functions to iterate over the heap regions in parallel. Threads
1208 // compete using the HeapRegionClaimer to claim the regions before
1209 // applying the closure on them.
1210 // The _from_worker_offset version uses the HeapRegionClaimer and
1211 // the worker id to calculate a start offset to prevent all workers to
1212 // start from the point.
1213 void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
1214 HeapRegionClaimer* hrclaimer,
1215 uint worker_id) const;
1216
1217 void heap_region_par_iterate_from_start(HeapRegionClosure* cl,
1218 HeapRegionClaimer* hrclaimer) const;
1219
1220 // Iterate over all regions in the collection set in parallel.
1221 void collection_set_par_iterate_all(HeapRegionClosure* cl,
1222 HeapRegionClaimer* hr_claimer,
1223 uint worker_id);
1224
1225 // Iterate over all regions currently in the current collection set.
1226 void collection_set_iterate_all(HeapRegionClosure* blk);
1227
1228 // Iterate over the regions in the current increment of the collection set.
1229 // Starts the iteration so that the start regions of a given worker id over the
1230 // set active_workers are evenly spread across the set of collection set regions
1231 // to be iterated.
1232 // The variant with the HeapRegionClaimer guarantees that the closure will be
1233 // applied to a particular region exactly once.
1234 void collection_set_iterate_increment_from(HeapRegionClosure *blk, uint worker_id) {
1235 collection_set_iterate_increment_from(blk, NULL, worker_id);
1236 }
1237 void collection_set_iterate_increment_from(HeapRegionClosure *blk, HeapRegionClaimer* hr_claimer, uint worker_id);
1238
1239 // Returns the HeapRegion that contains addr. addr must not be NULL.
1240 template <class T>
1241 inline HeapRegion* heap_region_containing(const T addr) const;
1242
1243 // Returns the HeapRegion that contains addr, or NULL if that is an uncommitted
1244 // region. addr must not be NULL.
1245 template <class T>
1246 inline HeapRegion* heap_region_containing_or_null(const T addr) const;
1247
1248 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1249 // each address in the (reserved) heap is a member of exactly
1250 // one block. The defining characteristic of a block is that it is
1251 // possible to find its size, and thus to progress forward to the next
1252 // block. (Blocks may be of different sizes.) Thus, blocks may
1253 // represent Java objects, or they might be free blocks in a
1254 // free-list-based heap (or subheap), as long as the two kinds are
1255 // distinguishable and the size of each is determinable.
1256
1257 // Returns the address of the start of the "block" that contains the
1258 // address "addr". We say "blocks" instead of "object" since some heaps
1259 // may not pack objects densely; a chunk may either be an object or a
1260 // non-object.
1261 HeapWord* block_start(const void* addr) const;
1262
1263 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1264 // the block is an object.
1265 bool block_is_obj(const HeapWord* addr) const;
1266
1267 // Section on thread-local allocation buffers (TLABs)
1268 // See CollectedHeap for semantics.
1269
1270 bool supports_tlab_allocation() const;
1271 size_t tlab_capacity(Thread* ignored) const;
1272 size_t tlab_used(Thread* ignored) const;
1273 size_t max_tlab_size() const;
1274 size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1275
1276 inline bool is_in_young(const oop obj);
1277
1278 // Returns "true" iff the given word_size is "very large".
1279 static bool is_humongous(size_t word_size) {
1280 // Note this has to be strictly greater-than as the TLABs
1281 // are capped at the humongous threshold and we want to
1282 // ensure that we don't try to allocate a TLAB as
1283 // humongous and that we don't allocate a humongous
1284 // object in a TLAB.
1285 return word_size > _humongous_object_threshold_in_words;
1286 }
1287
1288 // Returns the humongous threshold for a specific region size
1289 static size_t humongous_threshold_for(size_t region_size) {
1290 return (region_size / 2);
1291 }
1292
1293 // Returns the number of regions the humongous object of the given word size
1294 // requires.
1295 static size_t humongous_obj_size_in_regions(size_t word_size);
1296
1297 // Print the maximum heap capacity.
1298 virtual size_t max_capacity() const;
1299
1300 // Return the size of reserved memory. Returns different value than max_capacity() when AllocateOldGenAt is used.
1301 virtual size_t max_reserved_capacity() const;
1302
1303 Tickspan time_since_last_collection() const { return Ticks::now() - _collection_pause_end; }
1304
1305 // Convenience function to be used in situations where the heap type can be
1306 // asserted to be this type.
1307 static G1CollectedHeap* heap() {
1308 return named_heap<G1CollectedHeap>(CollectedHeap::G1);
1309 }
1310
1311 void set_region_short_lived_locked(HeapRegion* hr);
1312 // add appropriate methods for any other surv rate groups
1313
1314 const G1SurvivorRegions* survivor() const { return &_survivor; }
1315
1316 uint eden_regions_count() const { return _eden.length(); }
1317 uint eden_regions_count(uint node_index) const { return _eden.regions_on_node(node_index); }
1318 uint survivor_regions_count() const { return _survivor.length(); }
1319 uint survivor_regions_count(uint node_index) const { return _survivor.regions_on_node(node_index); }
1320 size_t eden_regions_used_bytes() const { return _eden.used_bytes(); }
1321 size_t survivor_regions_used_bytes() const { return _survivor.used_bytes(); }
1322 uint young_regions_count() const { return _eden.length() + _survivor.length(); }
1323 uint old_regions_count() const { return _old_set.length(); }
1324 uint archive_regions_count() const { return _archive_set.length(); }
1325 uint humongous_regions_count() const { return _humongous_set.length(); }
1326
1327 #ifdef ASSERT
1328 bool check_young_list_empty();
1329 #endif
1330
1331 // *** Stuff related to concurrent marking. It's not clear to me that so
1332 // many of these need to be public.
1333
1334 // The functions below are helper functions that a subclass of
1335 // "CollectedHeap" can use in the implementation of its virtual
1336 // functions.
1337 // This performs a concurrent marking of the live objects in a
1338 // bitmap off to the side.
1339 void do_concurrent_mark();
1340
1341 bool is_marked_next(oop obj) const;
1342
1343 // Determine if an object is dead, given the object and also
1344 // the region to which the object belongs. An object is dead
1345 // iff a) it was not allocated since the last mark, b) it
1346 // is not marked, and c) it is not in an archive region.
1347 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1348 return
1349 hr->is_obj_dead(obj, _cm->prev_mark_bitmap()) &&
1350 !hr->is_archive();
1351 }
1352
1353 // This function returns true when an object has been
1354 // around since the previous marking and hasn't yet
1355 // been marked during this marking, and is not in an archive region.
1356 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1357 return
1358 !hr->obj_allocated_since_next_marking(obj) &&
1359 !is_marked_next(obj) &&
1360 !hr->is_archive();
1361 }
1362
1363 // Determine if an object is dead, given only the object itself.
1364 // This will find the region to which the object belongs and
1365 // then call the region version of the same function.
1366
1367 // Added if it is NULL it isn't dead.
1368
1369 inline bool is_obj_dead(const oop obj) const;
1370
1371 inline bool is_obj_ill(const oop obj) const;
1372
1373 inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const;
1374 inline bool is_obj_dead_full(const oop obj) const;
1375
1376 G1ConcurrentMark* concurrent_mark() const { return _cm; }
1377
1378 // Refinement
1379
1380 G1ConcurrentRefine* concurrent_refine() const { return _cr; }
1381
1382 // Optimized nmethod scanning support routines
1383
1384 // Register the given nmethod with the G1 heap.
1385 virtual void register_nmethod(nmethod* nm);
1386
1387 // Unregister the given nmethod from the G1 heap.
1388 virtual void unregister_nmethod(nmethod* nm);
1389
1390 // No nmethod flushing needed.
1391 virtual void flush_nmethod(nmethod* nm) {}
1392
1393 // No nmethod verification implemented.
1394 virtual void verify_nmethod(nmethod* nm) {}
1395
1396 // Free up superfluous code root memory.
1397 void purge_code_root_memory();
1398
1399 // Rebuild the strong code root lists for each region
1400 // after a full GC.
1401 void rebuild_strong_code_roots();
1402
1403 // Partial cleaning of VM internal data structures.
1404 void string_dedup_cleaning(BoolObjectClosure* is_alive,
1405 OopClosure* keep_alive,
1406 G1GCPhaseTimes* phase_times = NULL);
1407
1408 // Performs cleaning of data structures after class unloading.
1409 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred);
1410
1411 // Redirty logged cards in the refinement queue.
1412 void redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs);
1413
1414 // Verification
1415
1416 // Deduplicate the string
1417 virtual void deduplicate_string(oop str);
1418
1419 // Perform any cleanup actions necessary before allowing a verification.
1420 virtual void prepare_for_verify();
1421
1422 // Perform verification.
1423
1424 // vo == UsePrevMarking -> use "prev" marking information,
1425 // vo == UseNextMarking -> use "next" marking information
1426 // vo == UseFullMarking -> use "next" marking bitmap but no TAMS
1427 //
1428 // NOTE: Only the "prev" marking information is guaranteed to be
1429 // consistent most of the time, so most calls to this should use
1430 // vo == UsePrevMarking.
1431 // Currently, there is only one case where this is called with
1432 // vo == UseNextMarking, which is to verify the "next" marking
1433 // information at the end of remark.
1434 // Currently there is only one place where this is called with
1435 // vo == UseFullMarking, which is to verify the marking during a
1436 // full GC.
1437 void verify(VerifyOption vo);
1438
1439 // WhiteBox testing support.
1440 virtual bool supports_concurrent_gc_breakpoints() const;
1441 bool is_heterogeneous_heap() const;
1442
1443 virtual WorkGang* get_safepoint_workers() { return _workers; }
1444
1445 // The methods below are here for convenience and dispatch the
1446 // appropriate method depending on value of the given VerifyOption
1447 // parameter. The values for that parameter, and their meanings,
1448 // are the same as those above.
1449
1450 bool is_obj_dead_cond(const oop obj,
1451 const HeapRegion* hr,
1452 const VerifyOption vo) const;
1453
1454 bool is_obj_dead_cond(const oop obj,
1455 const VerifyOption vo) const;
1456
1457 G1HeapSummary create_g1_heap_summary();
1458 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats);
1459
1460 // Printing
1461 private:
1462 void print_heap_regions() const;
1463 void print_regions_on(outputStream* st) const;
1464
1465 public:
1466 virtual void print_on(outputStream* st) const;
1467 virtual void print_extended_on(outputStream* st) const;
1468 virtual void print_on_error(outputStream* st) const;
1469
1470 virtual void gc_threads_do(ThreadClosure* tc) const;
1471
1472 // Override
1473 void print_tracing_info() const;
1474
1475 // The following two methods are helpful for debugging RSet issues.
1476 void print_cset_rsets() PRODUCT_RETURN;
1477 void print_all_rsets() PRODUCT_RETURN;
1478
1479 // Used to print information about locations in the hs_err file.
1480 virtual bool print_location(outputStream* st, void* addr) const;
1481 };
1482
1483 class G1ParEvacuateFollowersClosure : public VoidClosure {
1484 private:
1485 double _start_term;
1486 double _term_time;
1487 size_t _term_attempts;
1488
1489 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
1490 void end_term_time() { _term_time += (os::elapsedTime() - _start_term); }
1491 protected:
1492 G1CollectedHeap* _g1h;
1493 G1ParScanThreadState* _par_scan_state;
1494 G1ScannerTasksQueueSet* _queues;
1495 TaskTerminator* _terminator;
1496 G1GCPhaseTimes::GCParPhases _phase;
1497
1498 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
1499 G1ScannerTasksQueueSet* queues() { return _queues; }
1500 TaskTerminator* terminator() { return _terminator; }
1501
1502 public:
1503 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
1504 G1ParScanThreadState* par_scan_state,
1505 G1ScannerTasksQueueSet* queues,
1506 TaskTerminator* terminator,
1507 G1GCPhaseTimes::GCParPhases phase)
1508 : _start_term(0.0), _term_time(0.0), _term_attempts(0),
1509 _g1h(g1h), _par_scan_state(par_scan_state),
1510 _queues(queues), _terminator(terminator), _phase(phase) {}
1511
1512 void do_void();
1513
1514 double term_time() const { return _term_time; }
1515 size_t term_attempts() const { return _term_attempts; }
1516
1517 private:
1518 inline bool offer_termination();
1519 };
1520
1521 #endif // SHARE_GC_G1_G1COLLECTEDHEAP_HPP