1 /*
2 * Copyright (c) 2001, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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24
25 #ifndef SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP
26 #define SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP
27
28 #include "gc/g1/evacuationInfo.hpp"
29 #include "gc/g1/g1BarrierSet.hpp"
30 #include "gc/g1/g1BiasedArray.hpp"
31 #include "gc/g1/g1CardTable.hpp"
32 #include "gc/g1/g1CollectionSet.hpp"
33 #include "gc/g1/g1CollectorState.hpp"
34 #include "gc/g1/g1ConcurrentMark.hpp"
35 #include "gc/g1/g1EdenRegions.hpp"
36 #include "gc/g1/g1EvacFailure.hpp"
37 #include "gc/g1/g1EvacStats.hpp"
38 #include "gc/g1/g1HeapTransition.hpp"
39 #include "gc/g1/g1HeapVerifier.hpp"
40 #include "gc/g1/g1HRPrinter.hpp"
41 #include "gc/g1/g1InCSetState.hpp"
42 #include "gc/g1/g1MonitoringSupport.hpp"
43 #include "gc/g1/g1SurvivorRegions.hpp"
44 #include "gc/g1/g1YCTypes.hpp"
45 #include "gc/g1/heapRegionManager.hpp"
46 #include "gc/g1/heapRegionSet.hpp"
47 #include "gc/shared/barrierSet.hpp"
48 #include "gc/shared/collectedHeap.hpp"
49 #include "gc/shared/gcHeapSummary.hpp"
50 #include "gc/shared/plab.hpp"
51 #include "gc/shared/preservedMarks.hpp"
52 #include "gc/shared/softRefPolicy.hpp"
53 #include "memory/memRegion.hpp"
54 #include "services/memoryManager.hpp"
55 #include "utilities/stack.hpp"
56
57 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
58 // It uses the "Garbage First" heap organization and algorithm, which
59 // may combine concurrent marking with parallel, incremental compaction of
60 // heap subsets that will yield large amounts of garbage.
61
62 // Forward declarations
63 class HeapRegion;
64 class HRRSCleanupTask;
65 class GenerationSpec;
66 class G1ParScanThreadState;
67 class G1ParScanThreadStateSet;
68 class G1ParScanThreadState;
69 class MemoryPool;
70 class ObjectClosure;
71 class SpaceClosure;
72 class CompactibleSpaceClosure;
73 class Space;
74 class G1CollectionSet;
75 class G1CollectorPolicy;
76 class G1Policy;
77 class G1HotCardCache;
78 class G1RemSet;
79 class G1YoungRemSetSamplingThread;
80 class HeapRegionRemSetIterator;
81 class G1ConcurrentMark;
82 class G1ConcurrentMarkThread;
83 class G1ConcurrentRefine;
84 class GenerationCounters;
85 class STWGCTimer;
86 class G1NewTracer;
87 class EvacuationFailedInfo;
88 class nmethod;
89 class WorkGang;
90 class G1Allocator;
91 class G1ArchiveAllocator;
92 class G1FullGCScope;
93 class G1HeapVerifier;
94 class G1HeapSizingPolicy;
95 class G1HeapSummary;
96 class G1EvacSummary;
97
98 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue;
99 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
100
101 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
102 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
103
104 // The G1 STW is alive closure.
105 // An instance is embedded into the G1CH and used as the
106 // (optional) _is_alive_non_header closure in the STW
107 // reference processor. It is also extensively used during
108 // reference processing during STW evacuation pauses.
109 class G1STWIsAliveClosure : public BoolObjectClosure {
110 G1CollectedHeap* _g1h;
111 public:
112 G1STWIsAliveClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
113 bool do_object_b(oop p);
114 };
115
116 class G1STWSubjectToDiscoveryClosure : public BoolObjectClosure {
117 G1CollectedHeap* _g1h;
118 public:
119 G1STWSubjectToDiscoveryClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
120 bool do_object_b(oop p);
121 };
122
123 class G1RegionMappingChangedListener : public G1MappingChangedListener {
124 private:
125 void reset_from_card_cache(uint start_idx, size_t num_regions);
126 public:
127 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
128 };
129
130 class G1CollectedHeap : public CollectedHeap {
131 friend class G1FreeCollectionSetTask;
132 friend class VM_CollectForMetadataAllocation;
133 friend class VM_G1CollectForAllocation;
134 friend class VM_G1CollectFull;
135 friend class VM_G1IdleCompaction;
136 friend class VMStructs;
137 friend class MutatorAllocRegion;
138 friend class G1FullCollector;
139 friend class G1GCAllocRegion;
140 friend class G1HeapVerifier;
141
142 // Closures used in implementation.
143 friend class G1ParScanThreadState;
144 friend class G1ParScanThreadStateSet;
145 friend class G1ParTask;
146 friend class G1PLABAllocator;
147 friend class G1PrepareCompactClosure;
148
149 // Other related classes.
150 friend class HeapRegionClaimer;
151
152 // Testing classes.
153 friend class G1CheckCSetFastTableClosure;
154
155 private:
156 G1YoungRemSetSamplingThread* _young_gen_sampling_thread;
157
158 WorkGang* _workers;
159 G1CollectorPolicy* _collector_policy;
160 G1CardTable* _card_table;
161
162 SoftRefPolicy _soft_ref_policy;
163
164 GCMemoryManager _memory_manager;
165 GCMemoryManager _full_gc_memory_manager;
166
167 MemoryPool* _eden_pool;
168 MemoryPool* _survivor_pool;
169 MemoryPool* _old_pool;
170
171 static size_t _humongous_object_threshold_in_words;
172
173 // It keeps track of the old regions.
174 HeapRegionSet _old_set;
175
176 // It keeps track of the humongous regions.
177 HeapRegionSet _humongous_set;
178
179 virtual void initialize_serviceability();
180
181 void eagerly_reclaim_humongous_regions();
182 // Start a new incremental collection set for the next pause.
183 void start_new_collection_set();
184
185 // The number of regions we could create by expansion.
186 uint _expansion_regions;
187
188 // The block offset table for the G1 heap.
189 G1BlockOffsetTable* _bot;
190
191 // Tears down the region sets / lists so that they are empty and the
192 // regions on the heap do not belong to a region set / list. The
193 // only exception is the humongous set which we leave unaltered. If
194 // free_list_only is true, it will only tear down the master free
195 // list. It is called before a Full GC (free_list_only == false) or
196 // before heap shrinking (free_list_only == true).
197 void tear_down_region_sets(bool free_list_only);
198
199 // Rebuilds the region sets / lists so that they are repopulated to
200 // reflect the contents of the heap. The only exception is the
201 // humongous set which was not torn down in the first place. If
202 // free_list_only is true, it will only rebuild the master free
203 // list. It is called after a Full GC (free_list_only == false) or
204 // after heap shrinking (free_list_only == true).
205 void rebuild_region_sets(bool free_list_only);
206
207 // Callback for region mapping changed events.
208 G1RegionMappingChangedListener _listener;
209
210 // The sequence of all heap regions in the heap.
211 HeapRegionManager _hrm;
212
213 // Manages all allocations with regions except humongous object allocations.
214 G1Allocator* _allocator;
215
216 // Manages all heap verification.
217 G1HeapVerifier* _verifier;
218
219 // Outside of GC pauses, the number of bytes used in all regions other
220 // than the current allocation region(s).
221 size_t _summary_bytes_used;
222
223 void increase_used(size_t bytes);
224 void decrease_used(size_t bytes);
225
226 void set_used(size_t bytes);
227
228 // Class that handles archive allocation ranges.
229 G1ArchiveAllocator* _archive_allocator;
230
231 // GC allocation statistics policy for survivors.
232 G1EvacStats _survivor_evac_stats;
233
234 // GC allocation statistics policy for tenured objects.
235 G1EvacStats _old_evac_stats;
236
237 // It specifies whether we should attempt to expand the heap after a
238 // region allocation failure. If heap expansion fails we set this to
239 // false so that we don't re-attempt the heap expansion (it's likely
240 // that subsequent expansion attempts will also fail if one fails).
241 // Currently, it is only consulted during GC and it's reset at the
242 // start of each GC.
243 bool _expand_heap_after_alloc_failure;
244
245 // Helper for monitoring and management support.
246 G1MonitoringSupport* _g1mm;
247
248 // Records whether the region at the given index is (still) a
249 // candidate for eager reclaim. Only valid for humongous start
250 // regions; other regions have unspecified values. Humongous start
251 // regions are initialized at start of collection pause, with
252 // candidates removed from the set as they are found reachable from
253 // roots or the young generation.
254 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> {
255 protected:
256 bool default_value() const { return false; }
257 public:
258 void clear() { G1BiasedMappedArray<bool>::clear(); }
259 void set_candidate(uint region, bool value) {
260 set_by_index(region, value);
261 }
262 bool is_candidate(uint region) {
263 return get_by_index(region);
264 }
265 };
266
267 HumongousReclaimCandidates _humongous_reclaim_candidates;
268 // Stores whether during humongous object registration we found candidate regions.
269 // If not, we can skip a few steps.
270 bool _has_humongous_reclaim_candidates;
271
272 G1HRPrinter _hr_printer;
273
274 // It decides whether an explicit GC should start a concurrent cycle
275 // instead of doing a STW GC. Currently, a concurrent cycle is
276 // explicitly started if:
277 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
278 // (b) cause == _g1_humongous_allocation
279 // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
280 // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent.
281 // (e) cause == _wb_conc_mark
282 bool should_do_concurrent_full_gc(GCCause::Cause cause);
283
284 // indicates whether we are in young or mixed GC mode
285 G1CollectorState _collector_state;
286
287 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
288 // concurrent cycles) we have started.
289 volatile uint _old_marking_cycles_started;
290
291 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
292 // concurrent cycles) we have completed.
293 volatile uint _old_marking_cycles_completed;
294
295 // This is a non-product method that is helpful for testing. It is
296 // called at the end of a GC and artificially expands the heap by
297 // allocating a number of dead regions. This way we can induce very
298 // frequent marking cycles and stress the cleanup / concurrent
299 // cleanup code more (as all the regions that will be allocated by
300 // this method will be found dead by the marking cycle).
301 void allocate_dummy_regions() PRODUCT_RETURN;
302
303 // If the HR printer is active, dump the state of the regions in the
304 // heap after a compaction.
305 void print_hrm_post_compaction();
306
307 // Create a memory mapper for auxiliary data structures of the given size and
308 // translation factor.
309 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description,
310 size_t size,
311 size_t translation_factor);
312
313 void trace_heap(GCWhen::Type when, const GCTracer* tracer);
314
315 // These are macros so that, if the assert fires, we get the correct
316 // line number, file, etc.
317
318 #define heap_locking_asserts_params(_extra_message_) \
319 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
320 (_extra_message_), \
321 BOOL_TO_STR(Heap_lock->owned_by_self()), \
322 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
323 BOOL_TO_STR(Thread::current()->is_VM_thread())
324
325 #define assert_heap_locked() \
326 do { \
327 assert(Heap_lock->owned_by_self(), \
328 heap_locking_asserts_params("should be holding the Heap_lock")); \
329 } while (0)
330
331 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
332 do { \
333 assert(Heap_lock->owned_by_self() || \
334 (SafepointSynchronize::is_at_safepoint() && \
335 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
336 heap_locking_asserts_params("should be holding the Heap_lock or " \
337 "should be at a safepoint")); \
338 } while (0)
339
340 #define assert_heap_locked_and_not_at_safepoint() \
341 do { \
342 assert(Heap_lock->owned_by_self() && \
343 !SafepointSynchronize::is_at_safepoint(), \
344 heap_locking_asserts_params("should be holding the Heap_lock and " \
345 "should not be at a safepoint")); \
346 } while (0)
347
348 #define assert_heap_not_locked() \
349 do { \
350 assert(!Heap_lock->owned_by_self(), \
351 heap_locking_asserts_params("should not be holding the Heap_lock")); \
352 } while (0)
353
354 #define assert_heap_not_locked_and_not_at_safepoint() \
355 do { \
356 assert(!Heap_lock->owned_by_self() && \
357 !SafepointSynchronize::is_at_safepoint(), \
358 heap_locking_asserts_params("should not be holding the Heap_lock and " \
359 "should not be at a safepoint")); \
360 } while (0)
361
362 #define assert_at_safepoint_on_vm_thread() \
363 do { \
364 assert_at_safepoint(); \
365 assert(Thread::current_or_null() != NULL, "no current thread"); \
366 assert(Thread::current()->is_VM_thread(), "current thread is not VM thread"); \
367 } while (0)
368
369 // The young region list.
370 G1EdenRegions _eden;
371 G1SurvivorRegions _survivor;
372
373 STWGCTimer* _gc_timer_stw;
374
375 G1NewTracer* _gc_tracer_stw;
376
377 // The current policy object for the collector.
378 G1Policy* _g1_policy;
379 G1HeapSizingPolicy* _heap_sizing_policy;
380
381 G1CollectionSet _collection_set;
382
383 // Try to allocate a single non-humongous HeapRegion sufficient for
384 // an allocation of the given word_size. If do_expand is true,
385 // attempt to expand the heap if necessary to satisfy the allocation
386 // request. If the region is to be used as an old region or for a
387 // humongous object, set is_old to true. If not, to false.
388 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand);
389
390 // Initialize a contiguous set of free regions of length num_regions
391 // and starting at index first so that they appear as a single
392 // humongous region.
393 HeapWord* humongous_obj_allocate_initialize_regions(uint first,
394 uint num_regions,
395 size_t word_size);
396
397 // Attempt to allocate a humongous object of the given size. Return
398 // NULL if unsuccessful.
399 HeapWord* humongous_obj_allocate(size_t word_size);
400
401 // The following two methods, allocate_new_tlab() and
402 // mem_allocate(), are the two main entry points from the runtime
403 // into the G1's allocation routines. They have the following
404 // assumptions:
405 //
406 // * They should both be called outside safepoints.
407 //
408 // * They should both be called without holding the Heap_lock.
409 //
410 // * All allocation requests for new TLABs should go to
411 // allocate_new_tlab().
412 //
413 // * All non-TLAB allocation requests should go to mem_allocate().
414 //
415 // * If either call cannot satisfy the allocation request using the
416 // current allocating region, they will try to get a new one. If
417 // this fails, they will attempt to do an evacuation pause and
418 // retry the allocation.
419 //
420 // * If all allocation attempts fail, even after trying to schedule
421 // an evacuation pause, allocate_new_tlab() will return NULL,
422 // whereas mem_allocate() will attempt a heap expansion and/or
423 // schedule a Full GC.
424 //
425 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
426 // should never be called with word_size being humongous. All
427 // humongous allocation requests should go to mem_allocate() which
428 // will satisfy them with a special path.
429
430 virtual HeapWord* allocate_new_tlab(size_t min_size,
431 size_t requested_size,
432 size_t* actual_size);
433
434 virtual HeapWord* mem_allocate(size_t word_size,
435 bool* gc_overhead_limit_was_exceeded);
436
437 // First-level mutator allocation attempt: try to allocate out of
438 // the mutator alloc region without taking the Heap_lock. This
439 // should only be used for non-humongous allocations.
440 inline HeapWord* attempt_allocation(size_t min_word_size,
441 size_t desired_word_size,
442 size_t* actual_word_size);
443
444 // Second-level mutator allocation attempt: take the Heap_lock and
445 // retry the allocation attempt, potentially scheduling a GC
446 // pause. This should only be used for non-humongous allocations.
447 HeapWord* attempt_allocation_slow(size_t word_size);
448
449 // Takes the Heap_lock and attempts a humongous allocation. It can
450 // potentially schedule a GC pause.
451 HeapWord* attempt_allocation_humongous(size_t word_size);
452
453 // Allocation attempt that should be called during safepoints (e.g.,
454 // at the end of a successful GC). expect_null_mutator_alloc_region
455 // specifies whether the mutator alloc region is expected to be NULL
456 // or not.
457 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
458 bool expect_null_mutator_alloc_region);
459
460 // These methods are the "callbacks" from the G1AllocRegion class.
461
462 // For mutator alloc regions.
463 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
464 void retire_mutator_alloc_region(HeapRegion* alloc_region,
465 size_t allocated_bytes);
466
467 // For GC alloc regions.
468 bool has_more_regions(InCSetState dest);
469 HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest);
470 void retire_gc_alloc_region(HeapRegion* alloc_region,
471 size_t allocated_bytes, InCSetState dest);
472
473 // - if explicit_gc is true, the GC is for a System.gc() etc,
474 // otherwise it's for a failed allocation.
475 // - if clear_all_soft_refs is true, all soft references should be
476 // cleared during the GC.
477 // - it returns false if it is unable to do the collection due to the
478 // GC locker being active, true otherwise.
479 bool do_full_collection(bool explicit_gc,
480 bool clear_all_soft_refs);
481
482 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread.
483 virtual void do_full_collection(bool clear_all_soft_refs);
484
485 // Resize the heap if necessary after a full collection.
486 void resize_if_necessary_after_full_collection();
487
488 // Callback from VM_G1CollectForAllocation operation.
489 // This function does everything necessary/possible to satisfy a
490 // failed allocation request (including collection, expansion, etc.)
491 HeapWord* satisfy_failed_allocation(size_t word_size,
492 bool* succeeded);
493 // Internal helpers used during full GC to split it up to
494 // increase readability.
495 void abort_concurrent_cycle();
496 void verify_before_full_collection(bool explicit_gc);
497 void prepare_heap_for_full_collection();
498 void prepare_heap_for_mutators();
499 void abort_refinement();
500 void verify_after_full_collection();
501 void print_heap_after_full_collection(G1HeapTransition* heap_transition);
502
503 // Helper method for satisfy_failed_allocation()
504 HeapWord* satisfy_failed_allocation_helper(size_t word_size,
505 bool do_gc,
506 bool clear_all_soft_refs,
507 bool expect_null_mutator_alloc_region,
508 bool* gc_succeeded);
509
510 // Attempting to expand the heap sufficiently
511 // to support an allocation of the given "word_size". If
512 // successful, perform the allocation and return the address of the
513 // allocated block, or else "NULL".
514 HeapWord* expand_and_allocate(size_t word_size);
515
516 // Process any reference objects discovered.
517 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states);
518
519 // If during an initial mark pause we may install a pending list head which is not
520 // otherwise reachable ensure that it is marked in the bitmap for concurrent marking
521 // to discover.
522 void make_pending_list_reachable();
523
524 // Merges the information gathered on a per-thread basis for all worker threads
525 // during GC into global variables.
526 void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states);
527 public:
528 G1YoungRemSetSamplingThread* sampling_thread() const { return _young_gen_sampling_thread; }
529
530 WorkGang* workers() const { return _workers; }
531
532 G1Allocator* allocator() {
533 return _allocator;
534 }
535
536 G1HeapVerifier* verifier() {
537 return _verifier;
538 }
539
540 G1MonitoringSupport* g1mm() {
541 assert(_g1mm != NULL, "should have been initialized");
542 return _g1mm;
543 }
544
545 // Expand the garbage-first heap by at least the given size (in bytes!).
546 // Returns true if the heap was expanded by the requested amount;
547 // false otherwise.
548 // (Rounds up to a HeapRegion boundary.)
549 bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL);
550
551 // Returns the PLAB statistics for a given destination.
552 inline G1EvacStats* alloc_buffer_stats(InCSetState dest);
553
554 // Determines PLAB size for a given destination.
555 inline size_t desired_plab_sz(InCSetState dest);
556
557 // Do anything common to GC's.
558 void gc_prologue(bool full);
559 void gc_epilogue(bool full);
560
561 // Does the given region fulfill remembered set based eager reclaim candidate requirements?
562 bool is_potential_eager_reclaim_candidate(HeapRegion* r) const;
563
564 // Modify the reclaim candidate set and test for presence.
565 // These are only valid for starts_humongous regions.
566 inline void set_humongous_reclaim_candidate(uint region, bool value);
567 inline bool is_humongous_reclaim_candidate(uint region);
568
569 // Remove from the reclaim candidate set. Also remove from the
570 // collection set so that later encounters avoid the slow path.
571 inline void set_humongous_is_live(oop obj);
572
573 // Register the given region to be part of the collection set.
574 inline void register_humongous_region_with_cset(uint index);
575 // Register regions with humongous objects (actually on the start region) in
576 // the in_cset_fast_test table.
577 void register_humongous_regions_with_cset();
578 // We register a region with the fast "in collection set" test. We
579 // simply set to true the array slot corresponding to this region.
580 void register_young_region_with_cset(HeapRegion* r) {
581 _in_cset_fast_test.set_in_young(r->hrm_index());
582 }
583 void register_old_region_with_cset(HeapRegion* r) {
584 _in_cset_fast_test.set_in_old(r->hrm_index());
585 }
586 void clear_in_cset(const HeapRegion* hr) {
587 _in_cset_fast_test.clear(hr);
588 }
589
590 void clear_cset_fast_test() {
591 _in_cset_fast_test.clear();
592 }
593
594 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause);
595
596 // This is called at the start of either a concurrent cycle or a Full
597 // GC to update the number of old marking cycles started.
598 void increment_old_marking_cycles_started();
599
600 // This is called at the end of either a concurrent cycle or a Full
601 // GC to update the number of old marking cycles completed. Those two
602 // can happen in a nested fashion, i.e., we start a concurrent
603 // cycle, a Full GC happens half-way through it which ends first,
604 // and then the cycle notices that a Full GC happened and ends
605 // too. The concurrent parameter is a boolean to help us do a bit
606 // tighter consistency checking in the method. If concurrent is
607 // false, the caller is the inner caller in the nesting (i.e., the
608 // Full GC). If concurrent is true, the caller is the outer caller
609 // in this nesting (i.e., the concurrent cycle). Further nesting is
610 // not currently supported. The end of this call also notifies
611 // the FullGCCount_lock in case a Java thread is waiting for a full
612 // GC to happen (e.g., it called System.gc() with
613 // +ExplicitGCInvokesConcurrent).
614 void increment_old_marking_cycles_completed(bool concurrent);
615
616 uint old_marking_cycles_completed() {
617 return _old_marking_cycles_completed;
618 }
619
620 G1HRPrinter* hr_printer() { return &_hr_printer; }
621
622 // Allocates a new heap region instance.
623 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr);
624
625 // Allocate the highest free region in the reserved heap. This will commit
626 // regions as necessary.
627 HeapRegion* alloc_highest_free_region();
628
629 // Frees a non-humongous region by initializing its contents and
630 // adding it to the free list that's passed as a parameter (this is
631 // usually a local list which will be appended to the master free
632 // list later). The used bytes of freed regions are accumulated in
633 // pre_used. If skip_remset is true, the region's RSet will not be freed
634 // up. If skip_hot_card_cache is true, the region's hot card cache will not
635 // be freed up. The assumption is that this will be done later.
636 // The locked parameter indicates if the caller has already taken
637 // care of proper synchronization. This may allow some optimizations.
638 void free_region(HeapRegion* hr,
639 FreeRegionList* free_list,
640 bool skip_remset,
641 bool skip_hot_card_cache = false,
642 bool locked = false);
643
644 // It dirties the cards that cover the block so that the post
645 // write barrier never queues anything when updating objects on this
646 // block. It is assumed (and in fact we assert) that the block
647 // belongs to a young region.
648 inline void dirty_young_block(HeapWord* start, size_t word_size);
649
650 // Frees a humongous region by collapsing it into individual regions
651 // and calling free_region() for each of them. The freed regions
652 // will be added to the free list that's passed as a parameter (this
653 // is usually a local list which will be appended to the master free
654 // list later).
655 // The method assumes that only a single thread is ever calling
656 // this for a particular region at once.
657 void free_humongous_region(HeapRegion* hr,
658 FreeRegionList* free_list);
659
660 // Facility for allocating in 'archive' regions in high heap memory and
661 // recording the allocated ranges. These should all be called from the
662 // VM thread at safepoints, without the heap lock held. They can be used
663 // to create and archive a set of heap regions which can be mapped at the
664 // same fixed addresses in a subsequent JVM invocation.
665 void begin_archive_alloc_range(bool open = false);
666
667 // Check if the requested size would be too large for an archive allocation.
668 bool is_archive_alloc_too_large(size_t word_size);
669
670 // Allocate memory of the requested size from the archive region. This will
671 // return NULL if the size is too large or if no memory is available. It
672 // does not trigger a garbage collection.
673 HeapWord* archive_mem_allocate(size_t word_size);
674
675 // Optionally aligns the end address and returns the allocated ranges in
676 // an array of MemRegions in order of ascending addresses.
677 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
678 size_t end_alignment_in_bytes = 0);
679
680 // Facility for allocating a fixed range within the heap and marking
681 // the containing regions as 'archive'. For use at JVM init time, when the
682 // caller may mmap archived heap data at the specified range(s).
683 // Verify that the MemRegions specified in the argument array are within the
684 // reserved heap.
685 bool check_archive_addresses(MemRegion* range, size_t count);
686
687 // Commit the appropriate G1 regions containing the specified MemRegions
688 // and mark them as 'archive' regions. The regions in the array must be
689 // non-overlapping and in order of ascending address.
690 bool alloc_archive_regions(MemRegion* range, size_t count, bool open);
691
692 // Insert any required filler objects in the G1 regions around the specified
693 // ranges to make the regions parseable. This must be called after
694 // alloc_archive_regions, and after class loading has occurred.
695 void fill_archive_regions(MemRegion* range, size_t count);
696
697 // For each of the specified MemRegions, uncommit the containing G1 regions
698 // which had been allocated by alloc_archive_regions. This should be called
699 // rather than fill_archive_regions at JVM init time if the archive file
700 // mapping failed, with the same non-overlapping and sorted MemRegion array.
701 void dealloc_archive_regions(MemRegion* range, size_t count);
702
703 oop materialize_archived_object(oop obj);
704
705 private:
706
707 // Shrink the garbage-first heap by at most the given size (in bytes!).
708 // (Rounds down to a HeapRegion boundary.)
709 void shrink(size_t expand_bytes);
710 void shrink_helper(size_t expand_bytes);
711
712 #if TASKQUEUE_STATS
713 static void print_taskqueue_stats_hdr(outputStream* const st);
714 void print_taskqueue_stats() const;
715 void reset_taskqueue_stats();
716 #endif // TASKQUEUE_STATS
717
718 // Schedule the VM operation that will do an evacuation pause to
719 // satisfy an allocation request of word_size. *succeeded will
720 // return whether the VM operation was successful (it did do an
721 // evacuation pause) or not (another thread beat us to it or the GC
722 // locker was active). Given that we should not be holding the
723 // Heap_lock when we enter this method, we will pass the
724 // gc_count_before (i.e., total_collections()) as a parameter since
725 // it has to be read while holding the Heap_lock. Currently, both
726 // methods that call do_collection_pause() release the Heap_lock
727 // before the call, so it's easy to read gc_count_before just before.
728 HeapWord* do_collection_pause(size_t word_size,
729 uint gc_count_before,
730 bool* succeeded,
731 GCCause::Cause gc_cause);
732
733 void wait_for_root_region_scanning();
734
735 // The guts of the incremental collection pause, executed by the vm
736 // thread. It returns false if it is unable to do the collection due
737 // to the GC locker being active, true otherwise
738 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
739
740 // Actually do the work of evacuating the collection set.
741 void evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states);
742
743 void pre_evacuate_collection_set();
744 void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss);
745
746 // Print the header for the per-thread termination statistics.
747 static void print_termination_stats_hdr();
748 // Print actual per-thread termination statistics.
749 void print_termination_stats(uint worker_id,
750 double elapsed_ms,
751 double strong_roots_ms,
752 double term_ms,
753 size_t term_attempts,
754 size_t alloc_buffer_waste,
755 size_t undo_waste) const;
756 // Update object copying statistics.
757 void record_obj_copy_mem_stats();
758
759 // The hot card cache for remembered set insertion optimization.
760 G1HotCardCache* _hot_card_cache;
761
762 // The g1 remembered set of the heap.
763 G1RemSet* _g1_rem_set;
764
765 // A set of cards that cover the objects for which the Rsets should be updated
766 // concurrently after the collection.
767 DirtyCardQueueSet _dirty_card_queue_set;
768
769 // After a collection pause, convert the regions in the collection set into free
770 // regions.
771 void free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words);
772
773 // Abandon the current collection set without recording policy
774 // statistics or updating free lists.
775 void abandon_collection_set(G1CollectionSet* collection_set);
776
777 // The concurrent marker (and the thread it runs in.)
778 G1ConcurrentMark* _cm;
779 G1ConcurrentMarkThread* _cm_thread;
780
781 // The concurrent refiner.
782 G1ConcurrentRefine* _cr;
783
784 // The parallel task queues
785 RefToScanQueueSet *_task_queues;
786
787 // True iff a evacuation has failed in the current collection.
788 bool _evacuation_failed;
789
790 EvacuationFailedInfo* _evacuation_failed_info_array;
791
792 // Failed evacuations cause some logical from-space objects to have
793 // forwarding pointers to themselves. Reset them.
794 void remove_self_forwarding_pointers();
795
796 // Restore the objects in the regions in the collection set after an
797 // evacuation failure.
798 void restore_after_evac_failure();
799
800 PreservedMarksSet _preserved_marks_set;
801
802 // Preserve the mark of "obj", if necessary, in preparation for its mark
803 // word being overwritten with a self-forwarding-pointer.
804 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m);
805
806 #ifndef PRODUCT
807 // Support for forcing evacuation failures. Analogous to
808 // PromotionFailureALot for the other collectors.
809
810 // Records whether G1EvacuationFailureALot should be in effect
811 // for the current GC
812 bool _evacuation_failure_alot_for_current_gc;
813
814 // Used to record the GC number for interval checking when
815 // determining whether G1EvaucationFailureALot is in effect
816 // for the current GC.
817 size_t _evacuation_failure_alot_gc_number;
818
819 // Count of the number of evacuations between failures.
820 volatile size_t _evacuation_failure_alot_count;
821
822 // Set whether G1EvacuationFailureALot should be in effect
823 // for the current GC (based upon the type of GC and which
824 // command line flags are set);
825 inline bool evacuation_failure_alot_for_gc_type(bool for_young_gc,
826 bool during_initial_mark,
827 bool mark_or_rebuild_in_progress);
828
829 inline void set_evacuation_failure_alot_for_current_gc();
830
831 // Return true if it's time to cause an evacuation failure.
832 inline bool evacuation_should_fail();
833
834 // Reset the G1EvacuationFailureALot counters. Should be called at
835 // the end of an evacuation pause in which an evacuation failure occurred.
836 inline void reset_evacuation_should_fail();
837 #endif // !PRODUCT
838
839 // ("Weak") Reference processing support.
840 //
841 // G1 has 2 instances of the reference processor class. One
842 // (_ref_processor_cm) handles reference object discovery
843 // and subsequent processing during concurrent marking cycles.
844 //
845 // The other (_ref_processor_stw) handles reference object
846 // discovery and processing during full GCs and incremental
847 // evacuation pauses.
848 //
849 // During an incremental pause, reference discovery will be
850 // temporarily disabled for _ref_processor_cm and will be
851 // enabled for _ref_processor_stw. At the end of the evacuation
852 // pause references discovered by _ref_processor_stw will be
853 // processed and discovery will be disabled. The previous
854 // setting for reference object discovery for _ref_processor_cm
855 // will be re-instated.
856 //
857 // At the start of marking:
858 // * Discovery by the CM ref processor is verified to be inactive
859 // and it's discovered lists are empty.
860 // * Discovery by the CM ref processor is then enabled.
861 //
862 // At the end of marking:
863 // * Any references on the CM ref processor's discovered
864 // lists are processed (possibly MT).
865 //
866 // At the start of full GC we:
867 // * Disable discovery by the CM ref processor and
868 // empty CM ref processor's discovered lists
869 // (without processing any entries).
870 // * Verify that the STW ref processor is inactive and it's
871 // discovered lists are empty.
872 // * Temporarily set STW ref processor discovery as single threaded.
873 // * Temporarily clear the STW ref processor's _is_alive_non_header
874 // field.
875 // * Finally enable discovery by the STW ref processor.
876 //
877 // The STW ref processor is used to record any discovered
878 // references during the full GC.
879 //
880 // At the end of a full GC we:
881 // * Enqueue any reference objects discovered by the STW ref processor
882 // that have non-live referents. This has the side-effect of
883 // making the STW ref processor inactive by disabling discovery.
884 // * Verify that the CM ref processor is still inactive
885 // and no references have been placed on it's discovered
886 // lists (also checked as a precondition during initial marking).
887
888 // The (stw) reference processor...
889 ReferenceProcessor* _ref_processor_stw;
890
891 // During reference object discovery, the _is_alive_non_header
892 // closure (if non-null) is applied to the referent object to
893 // determine whether the referent is live. If so then the
894 // reference object does not need to be 'discovered' and can
895 // be treated as a regular oop. This has the benefit of reducing
896 // the number of 'discovered' reference objects that need to
897 // be processed.
898 //
899 // Instance of the is_alive closure for embedding into the
900 // STW reference processor as the _is_alive_non_header field.
901 // Supplying a value for the _is_alive_non_header field is
902 // optional but doing so prevents unnecessary additions to
903 // the discovered lists during reference discovery.
904 G1STWIsAliveClosure _is_alive_closure_stw;
905
906 G1STWSubjectToDiscoveryClosure _is_subject_to_discovery_stw;
907
908 // The (concurrent marking) reference processor...
909 ReferenceProcessor* _ref_processor_cm;
910
911 // Instance of the concurrent mark is_alive closure for embedding
912 // into the Concurrent Marking reference processor as the
913 // _is_alive_non_header field. Supplying a value for the
914 // _is_alive_non_header field is optional but doing so prevents
915 // unnecessary additions to the discovered lists during reference
916 // discovery.
917 G1CMIsAliveClosure _is_alive_closure_cm;
918
919 G1CMSubjectToDiscoveryClosure _is_subject_to_discovery_cm;
920 public:
921
922 RefToScanQueue *task_queue(uint i) const;
923
924 uint num_task_queues() const;
925
926 // A set of cards where updates happened during the GC
927 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
928
929 // Create a G1CollectedHeap with the specified policy.
930 // Must call the initialize method afterwards.
931 // May not return if something goes wrong.
932 G1CollectedHeap(G1CollectorPolicy* policy);
933
934 private:
935 jint initialize_concurrent_refinement();
936 jint initialize_young_gen_sampling_thread();
937 public:
938 // Initialize the G1CollectedHeap to have the initial and
939 // maximum sizes and remembered and barrier sets
940 // specified by the policy object.
941 jint initialize();
942
943 virtual void stop();
944 virtual void safepoint_synchronize_begin();
945 virtual void safepoint_synchronize_end();
946
947 // Return the (conservative) maximum heap alignment for any G1 heap
948 static size_t conservative_max_heap_alignment();
949
950 // Does operations required after initialization has been done.
951 void post_initialize();
952
953 // Initialize weak reference processing.
954 void ref_processing_init();
955
956 virtual Name kind() const {
957 return CollectedHeap::G1;
958 }
959
960 virtual const char* name() const {
961 return "G1";
962 }
963
964 const G1CollectorState* collector_state() const { return &_collector_state; }
965 G1CollectorState* collector_state() { return &_collector_state; }
966
967 // The current policy object for the collector.
968 G1Policy* g1_policy() const { return _g1_policy; }
969
970 const G1CollectionSet* collection_set() const { return &_collection_set; }
971 G1CollectionSet* collection_set() { return &_collection_set; }
972
973 virtual CollectorPolicy* collector_policy() const;
974
975 virtual SoftRefPolicy* soft_ref_policy();
976
977 virtual GrowableArray<GCMemoryManager*> memory_managers();
978 virtual GrowableArray<MemoryPool*> memory_pools();
979
980 // The rem set and barrier set.
981 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
982
983 // Try to minimize the remembered set.
984 void scrub_rem_set();
985
986 // Apply the given closure on all cards in the Hot Card Cache, emptying it.
987 void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i);
988
989 // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it.
990 void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i);
991
992 // The shared block offset table array.
993 G1BlockOffsetTable* bot() const { return _bot; }
994
995 // Reference Processing accessors
996
997 // The STW reference processor....
998 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
999
1000 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; }
1001
1002 // The Concurrent Marking reference processor...
1003 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1004
1005 size_t unused_committed_regions_in_bytes() const;
1006 virtual size_t capacity() const;
1007 virtual size_t used() const;
1008 // This should be called when we're not holding the heap lock. The
1009 // result might be a bit inaccurate.
1010 size_t used_unlocked() const;
1011 size_t recalculate_used() const;
1012
1013 // These virtual functions do the actual allocation.
1014 // Some heaps may offer a contiguous region for shared non-blocking
1015 // allocation, via inlined code (by exporting the address of the top and
1016 // end fields defining the extent of the contiguous allocation region.)
1017 // But G1CollectedHeap doesn't yet support this.
1018
1019 virtual bool is_maximal_no_gc() const {
1020 return _hrm.available() == 0;
1021 }
1022
1023 // Returns whether there are any regions left in the heap for allocation.
1024 bool has_regions_left_for_allocation() const {
1025 return !is_maximal_no_gc() || num_free_regions() != 0;
1026 }
1027
1028 // The current number of regions in the heap.
1029 uint num_regions() const { return _hrm.length(); }
1030
1031 // The max number of regions in the heap.
1032 uint max_regions() const { return _hrm.max_length(); }
1033
1034 // The number of regions that are completely free.
1035 uint num_free_regions() const { return _hrm.num_free_regions(); }
1036
1037 MemoryUsage get_auxiliary_data_memory_usage() const {
1038 return _hrm.get_auxiliary_data_memory_usage();
1039 }
1040
1041 // The number of regions that are not completely free.
1042 uint num_used_regions() const { return num_regions() - num_free_regions(); }
1043
1044 #ifdef ASSERT
1045 bool is_on_master_free_list(HeapRegion* hr) {
1046 return _hrm.is_free(hr);
1047 }
1048 #endif // ASSERT
1049
1050 inline void old_set_add(HeapRegion* hr);
1051 inline void old_set_remove(HeapRegion* hr);
1052
1053 size_t non_young_capacity_bytes() {
1054 return (_old_set.length() + _humongous_set.length()) * HeapRegion::GrainBytes;
1055 }
1056
1057 // Determine whether the given region is one that we are using as an
1058 // old GC alloc region.
1059 bool is_old_gc_alloc_region(HeapRegion* hr);
1060
1061 // Perform a collection of the heap; intended for use in implementing
1062 // "System.gc". This probably implies as full a collection as the
1063 // "CollectedHeap" supports.
1064 virtual void collect(GCCause::Cause cause);
1065
1066 // True iff an evacuation has failed in the most-recent collection.
1067 bool evacuation_failed() { return _evacuation_failed; }
1068
1069 void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed);
1070 void prepend_to_freelist(FreeRegionList* list);
1071 void decrement_summary_bytes(size_t bytes);
1072
1073 virtual bool is_in(const void* p) const;
1074 #ifdef ASSERT
1075 // Returns whether p is in one of the available areas of the heap. Slow but
1076 // extensive version.
1077 bool is_in_exact(const void* p) const;
1078 #endif
1079
1080 // Return "TRUE" iff the given object address is within the collection
1081 // set. Assumes that the reference points into the heap.
1082 inline bool is_in_cset(const HeapRegion *hr);
1083 inline bool is_in_cset(oop obj);
1084 inline bool is_in_cset(HeapWord* addr);
1085
1086 inline bool is_in_cset_or_humongous(const oop obj);
1087
1088 private:
1089 // This array is used for a quick test on whether a reference points into
1090 // the collection set or not. Each of the array's elements denotes whether the
1091 // corresponding region is in the collection set or not.
1092 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test;
1093
1094 public:
1095
1096 inline InCSetState in_cset_state(const oop obj);
1097
1098 // Return "TRUE" iff the given object address is in the reserved
1099 // region of g1.
1100 bool is_in_g1_reserved(const void* p) const {
1101 return _hrm.reserved().contains(p);
1102 }
1103
1104 // Returns a MemRegion that corresponds to the space that has been
1105 // reserved for the heap
1106 MemRegion g1_reserved() const {
1107 return _hrm.reserved();
1108 }
1109
1110 virtual bool is_in_closed_subset(const void* p) const;
1111
1112 G1HotCardCache* g1_hot_card_cache() const { return _hot_card_cache; }
1113
1114 G1CardTable* card_table() const {
1115 return _card_table;
1116 }
1117
1118 // Iteration functions.
1119
1120 // Iterate over all objects, calling "cl.do_object" on each.
1121 virtual void object_iterate(ObjectClosure* cl);
1122
1123 virtual void safe_object_iterate(ObjectClosure* cl) {
1124 object_iterate(cl);
1125 }
1126
1127 // Iterate over heap regions, in address order, terminating the
1128 // iteration early if the "do_heap_region" method returns "true".
1129 void heap_region_iterate(HeapRegionClosure* blk) const;
1130
1131 // Return the region with the given index. It assumes the index is valid.
1132 inline HeapRegion* region_at(uint index) const;
1133
1134 // Return the next region (by index) that is part of the same
1135 // humongous object that hr is part of.
1136 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const;
1137
1138 // Calculate the region index of the given address. Given address must be
1139 // within the heap.
1140 inline uint addr_to_region(HeapWord* addr) const;
1141
1142 inline HeapWord* bottom_addr_for_region(uint index) const;
1143
1144 // Two functions to iterate over the heap regions in parallel. Threads
1145 // compete using the HeapRegionClaimer to claim the regions before
1146 // applying the closure on them.
1147 // The _from_worker_offset version uses the HeapRegionClaimer and
1148 // the worker id to calculate a start offset to prevent all workers to
1149 // start from the point.
1150 void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
1151 HeapRegionClaimer* hrclaimer,
1152 uint worker_id) const;
1153
1154 void heap_region_par_iterate_from_start(HeapRegionClosure* cl,
1155 HeapRegionClaimer* hrclaimer) const;
1156
1157 // Iterate over the regions (if any) in the current collection set.
1158 void collection_set_iterate(HeapRegionClosure* blk);
1159
1160 // Iterate over the regions (if any) in the current collection set. Starts the
1161 // iteration over the entire collection set so that the start regions of a given
1162 // worker id over the set active_workers are evenly spread across the set of
1163 // collection set regions.
1164 void collection_set_iterate_from(HeapRegionClosure *blk, uint worker_id);
1165
1166 // Returns the HeapRegion that contains addr. addr must not be NULL.
1167 template <class T>
1168 inline HeapRegion* heap_region_containing(const T addr) const;
1169
1170 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1171 // each address in the (reserved) heap is a member of exactly
1172 // one block. The defining characteristic of a block is that it is
1173 // possible to find its size, and thus to progress forward to the next
1174 // block. (Blocks may be of different sizes.) Thus, blocks may
1175 // represent Java objects, or they might be free blocks in a
1176 // free-list-based heap (or subheap), as long as the two kinds are
1177 // distinguishable and the size of each is determinable.
1178
1179 // Returns the address of the start of the "block" that contains the
1180 // address "addr". We say "blocks" instead of "object" since some heaps
1181 // may not pack objects densely; a chunk may either be an object or a
1182 // non-object.
1183 virtual HeapWord* block_start(const void* addr) const;
1184
1185 // Requires "addr" to be the start of a chunk, and returns its size.
1186 // "addr + size" is required to be the start of a new chunk, or the end
1187 // of the active area of the heap.
1188 virtual size_t block_size(const HeapWord* addr) const;
1189
1190 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1191 // the block is an object.
1192 virtual bool block_is_obj(const HeapWord* addr) const;
1193
1194 // Section on thread-local allocation buffers (TLABs)
1195 // See CollectedHeap for semantics.
1196
1197 bool supports_tlab_allocation() const;
1198 size_t tlab_capacity(Thread* ignored) const;
1199 size_t tlab_used(Thread* ignored) const;
1200 size_t max_tlab_size() const;
1201 size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1202
1203 inline bool is_in_young(const oop obj);
1204
1205 // Returns "true" iff the given word_size is "very large".
1206 static bool is_humongous(size_t word_size) {
1207 // Note this has to be strictly greater-than as the TLABs
1208 // are capped at the humongous threshold and we want to
1209 // ensure that we don't try to allocate a TLAB as
1210 // humongous and that we don't allocate a humongous
1211 // object in a TLAB.
1212 return word_size > _humongous_object_threshold_in_words;
1213 }
1214
1215 // Returns the humongous threshold for a specific region size
1216 static size_t humongous_threshold_for(size_t region_size) {
1217 return (region_size / 2);
1218 }
1219
1220 // Returns the number of regions the humongous object of the given word size
1221 // requires.
1222 static size_t humongous_obj_size_in_regions(size_t word_size);
1223
1224 // Print the maximum heap capacity.
1225 virtual size_t max_capacity() const;
1226
1227 virtual jlong millis_since_last_gc();
1228
1229
1230 // Convenience function to be used in situations where the heap type can be
1231 // asserted to be this type.
1232 static G1CollectedHeap* heap();
1233
1234 void set_region_short_lived_locked(HeapRegion* hr);
1235 // add appropriate methods for any other surv rate groups
1236
1237 const G1SurvivorRegions* survivor() const { return &_survivor; }
1238
1239 uint survivor_regions_count() const {
1240 return _survivor.length();
1241 }
1242
1243 uint eden_regions_count() const {
1244 return _eden.length();
1245 }
1246
1247 uint young_regions_count() const {
1248 return _eden.length() + _survivor.length();
1249 }
1250
1251 uint old_regions_count() const { return _old_set.length(); }
1252
1253 uint humongous_regions_count() const { return _humongous_set.length(); }
1254
1255 #ifdef ASSERT
1256 bool check_young_list_empty();
1257 #endif
1258
1259 // *** Stuff related to concurrent marking. It's not clear to me that so
1260 // many of these need to be public.
1261
1262 // The functions below are helper functions that a subclass of
1263 // "CollectedHeap" can use in the implementation of its virtual
1264 // functions.
1265 // This performs a concurrent marking of the live objects in a
1266 // bitmap off to the side.
1267 void do_concurrent_mark();
1268
1269 bool is_marked_next(oop obj) const;
1270
1271 // Determine if an object is dead, given the object and also
1272 // the region to which the object belongs. An object is dead
1273 // iff a) it was not allocated since the last mark, b) it
1274 // is not marked, and c) it is not in an archive region.
1275 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1276 return
1277 hr->is_obj_dead(obj, _cm->prev_mark_bitmap()) &&
1278 !hr->is_archive();
1279 }
1280
1281 // This function returns true when an object has been
1282 // around since the previous marking and hasn't yet
1283 // been marked during this marking, and is not in an archive region.
1284 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1285 return
1286 !hr->obj_allocated_since_next_marking(obj) &&
1287 !is_marked_next(obj) &&
1288 !hr->is_archive();
1289 }
1290
1291 // Determine if an object is dead, given only the object itself.
1292 // This will find the region to which the object belongs and
1293 // then call the region version of the same function.
1294
1295 // Added if it is NULL it isn't dead.
1296
1297 inline bool is_obj_dead(const oop obj) const;
1298
1299 inline bool is_obj_ill(const oop obj) const;
1300
1301 inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const;
1302 inline bool is_obj_dead_full(const oop obj) const;
1303
1304 G1ConcurrentMark* concurrent_mark() const { return _cm; }
1305
1306 // Refinement
1307
1308 G1ConcurrentRefine* concurrent_refine() const { return _cr; }
1309
1310 // Optimized nmethod scanning support routines
1311
1312 // Is an oop scavengeable
1313 virtual bool is_scavengable(oop obj);
1314
1315 // Register the given nmethod with the G1 heap.
1316 virtual void register_nmethod(nmethod* nm);
1317
1318 // Unregister the given nmethod from the G1 heap.
1319 virtual void unregister_nmethod(nmethod* nm);
1320
1321 // Free up superfluous code root memory.
1322 void purge_code_root_memory();
1323
1324 // Rebuild the strong code root lists for each region
1325 // after a full GC.
1326 void rebuild_strong_code_roots();
1327
1328 // Partial cleaning used when class unloading is disabled.
1329 // Let the caller choose what structures to clean out:
1330 // - StringTable
1331 // - SymbolTable
1332 // - StringDeduplication structures
1333 void partial_cleaning(BoolObjectClosure* is_alive, bool unlink_strings, bool unlink_symbols, bool unlink_string_dedup);
1334
1335 // Complete cleaning used when class unloading is enabled.
1336 // Cleans out all structures handled by partial_cleaning and also the CodeCache.
1337 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred);
1338
1339 // Redirty logged cards in the refinement queue.
1340 void redirty_logged_cards();
1341 // Verification
1342
1343 // Deduplicate the string
1344 virtual void deduplicate_string(oop str);
1345
1346 // Perform any cleanup actions necessary before allowing a verification.
1347 virtual void prepare_for_verify();
1348
1349 // Perform verification.
1350
1351 // vo == UsePrevMarking -> use "prev" marking information,
1352 // vo == UseNextMarking -> use "next" marking information
1353 // vo == UseFullMarking -> use "next" marking bitmap but no TAMS
1354 //
1355 // NOTE: Only the "prev" marking information is guaranteed to be
1356 // consistent most of the time, so most calls to this should use
1357 // vo == UsePrevMarking.
1358 // Currently, there is only one case where this is called with
1359 // vo == UseNextMarking, which is to verify the "next" marking
1360 // information at the end of remark.
1361 // Currently there is only one place where this is called with
1362 // vo == UseFullMarking, which is to verify the marking during a
1363 // full GC.
1364 void verify(VerifyOption vo);
1365
1366 // WhiteBox testing support.
1367 virtual bool supports_concurrent_phase_control() const;
1368 virtual const char* const* concurrent_phases() const;
1369 virtual bool request_concurrent_phase(const char* phase);
1370
1371 virtual WorkGang* get_safepoint_workers() { return _workers; }
1372
1373 // The methods below are here for convenience and dispatch the
1374 // appropriate method depending on value of the given VerifyOption
1375 // parameter. The values for that parameter, and their meanings,
1376 // are the same as those above.
1377
1378 bool is_obj_dead_cond(const oop obj,
1379 const HeapRegion* hr,
1380 const VerifyOption vo) const;
1381
1382 bool is_obj_dead_cond(const oop obj,
1383 const VerifyOption vo) const;
1384
1385 G1HeapSummary create_g1_heap_summary();
1386 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats);
1387
1388 // Printing
1389 private:
1390 void print_heap_regions() const;
1391 void print_regions_on(outputStream* st) const;
1392
1393 public:
1394 virtual void print_on(outputStream* st) const;
1395 virtual void print_extended_on(outputStream* st) const;
1396 virtual void print_on_error(outputStream* st) const;
1397
1398 virtual void print_gc_threads_on(outputStream* st) const;
1399 virtual void gc_threads_do(ThreadClosure* tc) const;
1400
1401 // Override
1402 void print_tracing_info() const;
1403
1404 // The following two methods are helpful for debugging RSet issues.
1405 void print_cset_rsets() PRODUCT_RETURN;
1406 void print_all_rsets() PRODUCT_RETURN;
1407
1408 public:
1409 size_t pending_card_num();
1410
1411 private:
1412 // Elapsed time since last call to resize_if_necessary_after_full_collection
1413 double _last_heap_resize;
1414 public:
1415 double last_heap_resize() { return _last_heap_resize; }
1416
1417 private:
1418 size_t _max_heap_capacity;
1419 };
1420
1421 class G1ParEvacuateFollowersClosure : public VoidClosure {
1422 private:
1423 double _start_term;
1424 double _term_time;
1425 size_t _term_attempts;
1426
1427 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
1428 void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
1429 protected:
1430 G1CollectedHeap* _g1h;
1431 G1ParScanThreadState* _par_scan_state;
1432 RefToScanQueueSet* _queues;
1433 ParallelTaskTerminator* _terminator;
1434
1435 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
1436 RefToScanQueueSet* queues() { return _queues; }
1437 ParallelTaskTerminator* terminator() { return _terminator; }
1438
1439 public:
1440 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
1441 G1ParScanThreadState* par_scan_state,
1442 RefToScanQueueSet* queues,
1443 ParallelTaskTerminator* terminator)
1444 : _g1h(g1h), _par_scan_state(par_scan_state),
1445 _queues(queues), _terminator(terminator),
1446 _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
1447
1448 void do_void();
1449
1450 double term_time() const { return _term_time; }
1451 size_t term_attempts() const { return _term_attempts; }
1452
1453 private:
1454 inline bool offer_termination();
1455 };
1456
1457 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP