1 /*
2 * Copyright (c) 2001, 2019, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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24
25 #ifndef SHARE_GC_G1_G1COLLECTEDHEAP_HPP
26 #define SHARE_GC_G1_G1COLLECTEDHEAP_HPP
27
28 #include "gc/g1/g1BarrierSet.hpp"
29 #include "gc/g1/g1BiasedArray.hpp"
30 #include "gc/g1/g1CardTable.hpp"
31 #include "gc/g1/g1CollectionSet.hpp"
32 #include "gc/g1/g1CollectorState.hpp"
33 #include "gc/g1/g1ConcurrentMark.hpp"
34 #include "gc/g1/g1DirtyCardQueue.hpp"
35 #include "gc/g1/g1EdenRegions.hpp"
36 #include "gc/g1/g1EvacFailure.hpp"
37 #include "gc/g1/g1EvacStats.hpp"
38 #include "gc/g1/g1EvacuationInfo.hpp"
39 #include "gc/g1/g1GCPhaseTimes.hpp"
40 #include "gc/g1/g1HeapTransition.hpp"
41 #include "gc/g1/g1HeapVerifier.hpp"
42 #include "gc/g1/g1HRPrinter.hpp"
43 #include "gc/g1/g1InCSetState.hpp"
44 #include "gc/g1/g1MonitoringSupport.hpp"
45 #include "gc/g1/g1SurvivorRegions.hpp"
46 #include "gc/g1/g1YCTypes.hpp"
47 #include "gc/g1/heapRegionManager.hpp"
48 #include "gc/g1/heapRegionSet.hpp"
49 #include "gc/g1/heterogeneousHeapRegionManager.hpp"
50 #include "gc/shared/barrierSet.hpp"
51 #include "gc/shared/collectedHeap.hpp"
52 #include "gc/shared/gcHeapSummary.hpp"
53 #include "gc/shared/plab.hpp"
54 #include "gc/shared/preservedMarks.hpp"
55 #include "gc/shared/softRefPolicy.hpp"
56 #include "memory/memRegion.hpp"
57 #include "utilities/stack.hpp"
58
59 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
60 // It uses the "Garbage First" heap organization and algorithm, which
61 // may combine concurrent marking with parallel, incremental compaction of
62 // heap subsets that will yield large amounts of garbage.
63
64 // Forward declarations
65 class HeapRegion;
66 class GenerationSpec;
67 class G1ParScanThreadState;
68 class G1ParScanThreadStateSet;
69 class G1ParScanThreadState;
70 class MemoryPool;
71 class MemoryManager;
72 class ObjectClosure;
73 class SpaceClosure;
74 class CompactibleSpaceClosure;
75 class Space;
76 class G1CollectionSet;
77 class G1CollectorPolicy;
78 class G1Policy;
79 class G1HotCardCache;
80 class G1RemSet;
81 class G1YoungRemSetSamplingThread;
82 class HeapRegionRemSetIterator;
83 class G1ConcurrentMark;
84 class G1ConcurrentMarkThread;
85 class G1ConcurrentRefine;
86 class GenerationCounters;
87 class STWGCTimer;
88 class G1NewTracer;
89 class EvacuationFailedInfo;
90 class nmethod;
91 class WorkGang;
92 class G1Allocator;
93 class G1ArchiveAllocator;
94 class G1FullGCScope;
95 class G1HeapVerifier;
96 class G1HeapSizingPolicy;
97 class G1HeapSummary;
98 class G1EvacSummary;
99
100 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue;
101 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
102
103 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
104 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
105
106 // The G1 STW is alive closure.
107 // An instance is embedded into the G1CH and used as the
108 // (optional) _is_alive_non_header closure in the STW
109 // reference processor. It is also extensively used during
110 // reference processing during STW evacuation pauses.
111 class G1STWIsAliveClosure : public BoolObjectClosure {
112 G1CollectedHeap* _g1h;
113 public:
114 G1STWIsAliveClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
115 bool do_object_b(oop p);
116 };
117
118 class G1STWSubjectToDiscoveryClosure : public BoolObjectClosure {
119 G1CollectedHeap* _g1h;
120 public:
121 G1STWSubjectToDiscoveryClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
122 bool do_object_b(oop p);
123 };
124
125 class G1RegionMappingChangedListener : public G1MappingChangedListener {
126 private:
127 void reset_from_card_cache(uint start_idx, size_t num_regions);
128 public:
129 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
130 };
131
132 class G1CollectedHeap : public CollectedHeap {
133 friend class G1FreeCollectionSetTask;
134 friend class VM_CollectForMetadataAllocation;
135 friend class VM_G1CollectForAllocation;
136 friend class VM_G1CollectFull;
137 friend class VMStructs;
138 friend class MutatorAllocRegion;
139 friend class G1FullCollector;
140 friend class G1GCAllocRegion;
141 friend class G1HeapVerifier;
142
143 // Closures used in implementation.
144 friend class G1ParScanThreadState;
145 friend class G1ParScanThreadStateSet;
146 friend class G1EvacuateRegionsTask;
147 friend class G1PLABAllocator;
148
149 // Other related classes.
150 friend class HeapRegionClaimer;
151
152 // Testing classes.
153 friend class 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 static size_t _humongous_object_threshold_in_words;
165
166 // These sets keep track of old, archive and humongous regions respectively.
167 HeapRegionSet _old_set;
168 HeapRegionSet _archive_set;
169 HeapRegionSet _humongous_set;
170
171 void eagerly_reclaim_humongous_regions();
172 // Start a new incremental collection set for the next pause.
173 void start_new_collection_set();
174
175 // The block offset table for the G1 heap.
176 G1BlockOffsetTable* _bot;
177
178 // Tears down the region sets / lists so that they are empty and the
179 // regions on the heap do not belong to a region set / list. The
180 // only exception is the humongous set which we leave unaltered. If
181 // free_list_only is true, it will only tear down the master free
182 // list. It is called before a Full GC (free_list_only == false) or
183 // before heap shrinking (free_list_only == true).
184 void tear_down_region_sets(bool free_list_only);
185
186 // Rebuilds the region sets / lists so that they are repopulated to
187 // reflect the contents of the heap. The only exception is the
188 // humongous set which was not torn down in the first place. If
189 // free_list_only is true, it will only rebuild the master free
190 // list. It is called after a Full GC (free_list_only == false) or
191 // after heap shrinking (free_list_only == true).
192 void rebuild_region_sets(bool free_list_only);
193
194 // Callback for region mapping changed events.
195 G1RegionMappingChangedListener _listener;
196
197 // The sequence of all heap regions in the heap.
198 HeapRegionManager* _hrm;
199
200 // Manages all allocations with regions except humongous object allocations.
201 G1Allocator* _allocator;
202
203 // Manages all heap verification.
204 G1HeapVerifier* _verifier;
205
206 // Outside of GC pauses, the number of bytes used in all regions other
207 // than the current allocation region(s).
208 size_t _summary_bytes_used;
209
210 void increase_used(size_t bytes);
211 void decrease_used(size_t bytes);
212
213 void set_used(size_t bytes);
214
215 // Class that handles archive allocation ranges.
216 G1ArchiveAllocator* _archive_allocator;
217
218 // GC allocation statistics policy for survivors.
219 G1EvacStats _survivor_evac_stats;
220
221 // GC allocation statistics policy for tenured objects.
222 G1EvacStats _old_evac_stats;
223
224 // It specifies whether we should attempt to expand the heap after a
225 // region allocation failure. If heap expansion fails we set this to
226 // false so that we don't re-attempt the heap expansion (it's likely
227 // that subsequent expansion attempts will also fail if one fails).
228 // Currently, it is only consulted during GC and it's reset at the
229 // start of each GC.
230 bool _expand_heap_after_alloc_failure;
231
232 // Helper for monitoring and management support.
233 G1MonitoringSupport* _g1mm;
234
235 // Records whether the region at the given index is (still) a
236 // candidate for eager reclaim. Only valid for humongous start
237 // regions; other regions have unspecified values. Humongous start
238 // regions are initialized at start of collection pause, with
239 // candidates removed from the set as they are found reachable from
240 // roots or the young generation.
241 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> {
242 protected:
243 bool default_value() const { return false; }
244 public:
245 void clear() { G1BiasedMappedArray<bool>::clear(); }
246 void set_candidate(uint region, bool value) {
247 set_by_index(region, value);
248 }
249 bool is_candidate(uint region) {
250 return get_by_index(region);
251 }
252 };
253
254 HumongousReclaimCandidates _humongous_reclaim_candidates;
255 // Stores whether during humongous object registration we found candidate regions.
256 // If not, we can skip a few steps.
257 bool _has_humongous_reclaim_candidates;
258
259 G1HRPrinter _hr_printer;
260
261 // It decides whether an explicit GC should start a concurrent cycle
262 // instead of doing a STW GC. Currently, a concurrent cycle is
263 // explicitly started if:
264 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
265 // (b) cause == _g1_humongous_allocation
266 // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
267 // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent.
268 // (e) cause == _wb_conc_mark
269 bool should_do_concurrent_full_gc(GCCause::Cause cause);
270
271 // Return true if should upgrade to full gc after an incremental one.
272 bool should_upgrade_to_full_gc(GCCause::Cause cause);
273
274 // indicates whether we are in young or mixed GC mode
275 G1CollectorState _collector_state;
276
277 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
278 // concurrent cycles) we have started.
279 volatile uint _old_marking_cycles_started;
280
281 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
282 // concurrent cycles) we have completed.
283 volatile uint _old_marking_cycles_completed;
284
285 // This is a non-product method that is helpful for testing. It is
286 // called at the end of a GC and artificially expands the heap by
287 // allocating a number of dead regions. This way we can induce very
288 // frequent marking cycles and stress the cleanup / concurrent
289 // cleanup code more (as all the regions that will be allocated by
290 // this method will be found dead by the marking cycle).
291 void allocate_dummy_regions() PRODUCT_RETURN;
292
293 // If the HR printer is active, dump the state of the regions in the
294 // heap after a compaction.
295 void print_hrm_post_compaction();
296
297 // Create a memory mapper for auxiliary data structures of the given size and
298 // translation factor.
299 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description,
300 size_t size,
301 size_t translation_factor);
302
303 void trace_heap(GCWhen::Type when, const GCTracer* tracer);
304
305 // These are macros so that, if the assert fires, we get the correct
306 // line number, file, etc.
307
308 #define heap_locking_asserts_params(_extra_message_) \
309 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
310 (_extra_message_), \
311 BOOL_TO_STR(Heap_lock->owned_by_self()), \
312 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
313 BOOL_TO_STR(Thread::current()->is_VM_thread())
314
315 #define assert_heap_locked() \
316 do { \
317 assert(Heap_lock->owned_by_self(), \
318 heap_locking_asserts_params("should be holding the Heap_lock")); \
319 } while (0)
320
321 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
322 do { \
323 assert(Heap_lock->owned_by_self() || \
324 (SafepointSynchronize::is_at_safepoint() && \
325 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
326 heap_locking_asserts_params("should be holding the Heap_lock or " \
327 "should be at a safepoint")); \
328 } while (0)
329
330 #define assert_heap_locked_and_not_at_safepoint() \
331 do { \
332 assert(Heap_lock->owned_by_self() && \
333 !SafepointSynchronize::is_at_safepoint(), \
334 heap_locking_asserts_params("should be holding the Heap_lock and " \
335 "should not be at a safepoint")); \
336 } while (0)
337
338 #define assert_heap_not_locked() \
339 do { \
340 assert(!Heap_lock->owned_by_self(), \
341 heap_locking_asserts_params("should not be holding the Heap_lock")); \
342 } while (0)
343
344 #define assert_heap_not_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 not be holding the Heap_lock and " \
349 "should not be at a safepoint")); \
350 } while (0)
351
352 #define assert_at_safepoint_on_vm_thread() \
353 do { \
354 assert_at_safepoint(); \
355 assert(Thread::current_or_null() != NULL, "no current thread"); \
356 assert(Thread::current()->is_VM_thread(), "current thread is not VM thread"); \
357 } while (0)
358
359 const char* young_gc_name() const;
360
361 // The young region list.
362 G1EdenRegions _eden;
363 G1SurvivorRegions _survivor;
364
365 STWGCTimer* _gc_timer_stw;
366
367 G1NewTracer* _gc_tracer_stw;
368
369 // The current policy object for the collector.
370 G1Policy* _policy;
371 G1HeapSizingPolicy* _heap_sizing_policy;
372
373 G1CollectionSet _collection_set;
374
375 // Try to allocate a single non-humongous HeapRegion sufficient for
376 // an allocation of the given word_size. If do_expand is true,
377 // attempt to expand the heap if necessary to satisfy the allocation
378 // request. 'type' takes the type of region to be allocated. (Use constants
379 // Old, Eden, Humongous, Survivor defined in HeapRegionType.)
380 HeapRegion* new_region(size_t word_size, HeapRegionType type, bool do_expand);
381
382 // Initialize a contiguous set of free regions of length num_regions
383 // and starting at index first so that they appear as a single
384 // humongous region.
385 HeapWord* humongous_obj_allocate_initialize_regions(uint first,
386 uint num_regions,
387 size_t word_size);
388
389 // Attempt to allocate a humongous object of the given size. Return
390 // NULL if unsuccessful.
391 HeapWord* humongous_obj_allocate(size_t word_size);
392
393 // The following two methods, allocate_new_tlab() and
394 // mem_allocate(), are the two main entry points from the runtime
395 // into the G1's allocation routines. They have the following
396 // assumptions:
397 //
398 // * They should both be called outside safepoints.
399 //
400 // * They should both be called without holding the Heap_lock.
401 //
402 // * All allocation requests for new TLABs should go to
403 // allocate_new_tlab().
404 //
405 // * All non-TLAB allocation requests should go to mem_allocate().
406 //
407 // * If either call cannot satisfy the allocation request using the
408 // current allocating region, they will try to get a new one. If
409 // this fails, they will attempt to do an evacuation pause and
410 // retry the allocation.
411 //
412 // * If all allocation attempts fail, even after trying to schedule
413 // an evacuation pause, allocate_new_tlab() will return NULL,
414 // whereas mem_allocate() will attempt a heap expansion and/or
415 // schedule a Full GC.
416 //
417 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
418 // should never be called with word_size being humongous. All
419 // humongous allocation requests should go to mem_allocate() which
420 // will satisfy them with a special path.
421
422 virtual HeapWord* allocate_new_tlab(size_t min_size,
423 size_t requested_size,
424 size_t* actual_size);
425
426 virtual HeapWord* mem_allocate(size_t word_size,
427 bool* gc_overhead_limit_was_exceeded);
428
429 // First-level mutator allocation attempt: try to allocate out of
430 // the mutator alloc region without taking the Heap_lock. This
431 // should only be used for non-humongous allocations.
432 inline HeapWord* attempt_allocation(size_t min_word_size,
433 size_t desired_word_size,
434 size_t* actual_word_size);
435
436 // Second-level mutator allocation attempt: take the Heap_lock and
437 // retry the allocation attempt, potentially scheduling a GC
438 // pause. This should only be used for non-humongous allocations.
439 HeapWord* attempt_allocation_slow(size_t word_size);
440
441 // Takes the Heap_lock and attempts a humongous allocation. It can
442 // potentially schedule a GC pause.
443 HeapWord* attempt_allocation_humongous(size_t word_size);
444
445 // Allocation attempt that should be called during safepoints (e.g.,
446 // at the end of a successful GC). expect_null_mutator_alloc_region
447 // specifies whether the mutator alloc region is expected to be NULL
448 // or not.
449 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
450 bool expect_null_mutator_alloc_region);
451
452 // These methods are the "callbacks" from the G1AllocRegion class.
453
454 // For mutator alloc regions.
455 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
456 void retire_mutator_alloc_region(HeapRegion* alloc_region,
457 size_t allocated_bytes);
458
459 // For GC alloc regions.
460 bool has_more_regions(InCSetState dest);
461 HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest);
462 void retire_gc_alloc_region(HeapRegion* alloc_region,
463 size_t allocated_bytes, InCSetState dest);
464
465 // - if explicit_gc is true, the GC is for a System.gc() etc,
466 // otherwise it's for a failed allocation.
467 // - if clear_all_soft_refs is true, all soft references should be
468 // cleared during the GC.
469 // - it returns false if it is unable to do the collection due to the
470 // GC locker being active, true otherwise.
471 bool do_full_collection(bool explicit_gc,
472 bool clear_all_soft_refs);
473
474 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread.
475 virtual void do_full_collection(bool clear_all_soft_refs);
476
477 // Callback from VM_G1CollectForAllocation operation.
478 // This function does everything necessary/possible to satisfy a
479 // failed allocation request (including collection, expansion, etc.)
480 HeapWord* satisfy_failed_allocation(size_t word_size,
481 bool* succeeded);
482 // Internal helpers used during full GC to split it up to
483 // increase readability.
484 void abort_concurrent_cycle();
485 void verify_before_full_collection(bool explicit_gc);
486 void prepare_heap_for_full_collection();
487 void prepare_heap_for_mutators();
488 void abort_refinement();
489 void verify_after_full_collection();
490 void print_heap_after_full_collection(G1HeapTransition* heap_transition);
491
492 // Helper method for satisfy_failed_allocation()
493 HeapWord* satisfy_failed_allocation_helper(size_t word_size,
494 bool do_gc,
495 bool clear_all_soft_refs,
496 bool expect_null_mutator_alloc_region,
497 bool* gc_succeeded);
498
499 // Attempting to expand the heap sufficiently
500 // to support an allocation of the given "word_size". If
501 // successful, perform the allocation and return the address of the
502 // allocated block, or else "NULL".
503 HeapWord* expand_and_allocate(size_t word_size);
504
505 // Process any reference objects discovered.
506 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states);
507
508 // If during an initial mark pause we may install a pending list head which is not
509 // otherwise reachable ensure that it is marked in the bitmap for concurrent marking
510 // to discover.
511 void make_pending_list_reachable();
512
513 // Merges the information gathered on a per-thread basis for all worker threads
514 // during GC into global variables.
515 void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states);
516 public:
517 G1YoungRemSetSamplingThread* sampling_thread() const { return _young_gen_sampling_thread; }
518
519 WorkGang* workers() const { return _workers; }
520
521 Tickspan run_task(AbstractGangTask* task, uint num_workers = 0);
522
523 G1Allocator* allocator() {
524 return _allocator;
525 }
526
527 G1HeapVerifier* verifier() {
528 return _verifier;
529 }
530
531 G1MonitoringSupport* g1mm() {
532 assert(_g1mm != NULL, "should have been initialized");
533 return _g1mm;
534 }
535
536 void resize_heap_if_necessary();
537
538 // Expand the garbage-first heap by at least the given size (in bytes!).
539 // Returns true if the heap was expanded by the requested amount;
540 // false otherwise.
541 // (Rounds up to a HeapRegion boundary.)
542 bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL);
543
544 // Returns the PLAB statistics for a given destination.
545 inline G1EvacStats* alloc_buffer_stats(InCSetState dest);
546
547 // Determines PLAB size for a given destination.
548 inline size_t desired_plab_sz(InCSetState dest);
549
550 // Do anything common to GC's.
551 void gc_prologue(bool full);
552 void gc_epilogue(bool full);
553
554 // Does the given region fulfill remembered set based eager reclaim candidate requirements?
555 bool is_potential_eager_reclaim_candidate(HeapRegion* r) const;
556
557 // Modify the reclaim candidate set and test for presence.
558 // These are only valid for starts_humongous regions.
559 inline void set_humongous_reclaim_candidate(uint region, bool value);
560 inline bool is_humongous_reclaim_candidate(uint region);
561
562 // Remove from the reclaim candidate set. Also remove from the
563 // collection set so that later encounters avoid the slow path.
564 inline void set_humongous_is_live(oop obj);
565
566 // Register the given region to be part of the collection set.
567 inline void register_humongous_region_with_cset(uint index);
568 // Register regions with humongous objects (actually on the start region) in
569 // the in_cset_fast_test table.
570 void register_humongous_regions_with_cset();
571 // We register a region with the fast "in collection set" test. We
572 // simply set to true the array slot corresponding to this region.
573 void register_young_region_with_cset(HeapRegion* r) {
574 _in_cset_fast_test.set_in_young(r->hrm_index());
575 }
576 void register_old_region_with_cset(HeapRegion* r) {
577 _in_cset_fast_test.set_in_old(r->hrm_index());
578 }
579 void register_optional_region_with_cset(HeapRegion* r) {
580 _in_cset_fast_test.set_optional(r->hrm_index());
581 }
582 void clear_in_cset(const HeapRegion* hr) {
583 _in_cset_fast_test.clear(hr);
584 }
585
586 void clear_cset_fast_test() {
587 _in_cset_fast_test.clear();
588 }
589
590 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause);
591
592 // This is called at the start of either a concurrent cycle or a Full
593 // GC to update the number of old marking cycles started.
594 void increment_old_marking_cycles_started();
595
596 // This is called at the end of either a concurrent cycle or a Full
597 // GC to update the number of old marking cycles completed. Those two
598 // can happen in a nested fashion, i.e., we start a concurrent
599 // cycle, a Full GC happens half-way through it which ends first,
600 // and then the cycle notices that a Full GC happened and ends
601 // too. The concurrent parameter is a boolean to help us do a bit
602 // tighter consistency checking in the method. If concurrent is
603 // false, the caller is the inner caller in the nesting (i.e., the
604 // Full GC). If concurrent is true, the caller is the outer caller
605 // in this nesting (i.e., the concurrent cycle). Further nesting is
606 // not currently supported. The end of this call also notifies
607 // the FullGCCount_lock in case a Java thread is waiting for a full
608 // GC to happen (e.g., it called System.gc() with
609 // +ExplicitGCInvokesConcurrent).
610 void increment_old_marking_cycles_completed(bool concurrent);
611
612 uint old_marking_cycles_completed() {
613 return _old_marking_cycles_completed;
614 }
615
616 G1HRPrinter* hr_printer() { return &_hr_printer; }
617
618 // Allocates a new heap region instance.
619 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr);
620
621 // Allocate the highest free region in the reserved heap. This will commit
622 // regions as necessary.
623 HeapRegion* alloc_highest_free_region();
624
625 // Frees a non-humongous region by initializing its contents and
626 // adding it to the free list that's passed as a parameter (this is
627 // usually a local list which will be appended to the master free
628 // list later). The used bytes of freed regions are accumulated in
629 // pre_used. If skip_remset is true, the region's RSet will not be freed
630 // up. If skip_hot_card_cache is true, the region's hot card cache will not
631 // be freed up. The assumption is that this will be done later.
632 // The locked parameter indicates if the caller has already taken
633 // care of proper synchronization. This may allow some optimizations.
634 void free_region(HeapRegion* hr,
635 FreeRegionList* free_list,
636 bool skip_remset,
637 bool skip_hot_card_cache = false,
638 bool locked = false);
639
640 // It dirties the cards that cover the block so that the post
641 // write barrier never queues anything when updating objects on this
642 // block. It is assumed (and in fact we assert) that the block
643 // belongs to a young region.
644 inline void dirty_young_block(HeapWord* start, size_t word_size);
645
646 // Frees a humongous region by collapsing it into individual regions
647 // and calling free_region() for each of them. The freed regions
648 // will be added to the free list that's passed as a parameter (this
649 // is usually a local list which will be appended to the master free
650 // list later).
651 // The method assumes that only a single thread is ever calling
652 // this for a particular region at once.
653 void free_humongous_region(HeapRegion* hr,
654 FreeRegionList* free_list);
655
656 // Facility for allocating in 'archive' regions in high heap memory and
657 // recording the allocated ranges. These should all be called from the
658 // VM thread at safepoints, without the heap lock held. They can be used
659 // to create and archive a set of heap regions which can be mapped at the
660 // same fixed addresses in a subsequent JVM invocation.
661 void begin_archive_alloc_range(bool open = false);
662
663 // Check if the requested size would be too large for an archive allocation.
664 bool is_archive_alloc_too_large(size_t word_size);
665
666 // Allocate memory of the requested size from the archive region. This will
667 // return NULL if the size is too large or if no memory is available. It
668 // does not trigger a garbage collection.
669 HeapWord* archive_mem_allocate(size_t word_size);
670
671 // Optionally aligns the end address and returns the allocated ranges in
672 // an array of MemRegions in order of ascending addresses.
673 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
674 size_t end_alignment_in_bytes = 0);
675
676 // Facility for allocating a fixed range within the heap and marking
677 // the containing regions as 'archive'. For use at JVM init time, when the
678 // caller may mmap archived heap data at the specified range(s).
679 // Verify that the MemRegions specified in the argument array are within the
680 // reserved heap.
681 bool check_archive_addresses(MemRegion* range, size_t count);
682
683 // Commit the appropriate G1 regions containing the specified MemRegions
684 // and mark them as 'archive' regions. The regions in the array must be
685 // non-overlapping and in order of ascending address.
686 bool alloc_archive_regions(MemRegion* range, size_t count, bool open);
687
688 // Insert any required filler objects in the G1 regions around the specified
689 // ranges to make the regions parseable. This must be called after
690 // alloc_archive_regions, and after class loading has occurred.
691 void fill_archive_regions(MemRegion* range, size_t count);
692
693 // For each of the specified MemRegions, uncommit the containing G1 regions
694 // which had been allocated by alloc_archive_regions. This should be called
695 // rather than fill_archive_regions at JVM init time if the archive file
696 // mapping failed, with the same non-overlapping and sorted MemRegion array.
697 void dealloc_archive_regions(MemRegion* range, size_t count, bool is_open);
698
699 oop materialize_archived_object(oop obj);
700
701 private:
702
703 // Shrink the garbage-first heap by at most the given size (in bytes!).
704 // (Rounds down to a HeapRegion boundary.)
705 void shrink(size_t expand_bytes);
706 void shrink_helper(size_t expand_bytes);
707
708 #if TASKQUEUE_STATS
709 static void print_taskqueue_stats_hdr(outputStream* const st);
710 void print_taskqueue_stats() const;
711 void reset_taskqueue_stats();
712 #endif // TASKQUEUE_STATS
713
714 // Schedule the VM operation that will do an evacuation pause to
715 // satisfy an allocation request of word_size. *succeeded will
716 // return whether the VM operation was successful (it did do an
717 // evacuation pause) or not (another thread beat us to it or the GC
718 // locker was active). Given that we should not be holding the
719 // Heap_lock when we enter this method, we will pass the
720 // gc_count_before (i.e., total_collections()) as a parameter since
721 // it has to be read while holding the Heap_lock. Currently, both
722 // methods that call do_collection_pause() release the Heap_lock
723 // before the call, so it's easy to read gc_count_before just before.
724 HeapWord* do_collection_pause(size_t word_size,
725 uint gc_count_before,
726 bool* succeeded,
727 GCCause::Cause gc_cause);
728
729 void wait_for_root_region_scanning();
730
731 // The guts of the incremental collection pause, executed by the vm
732 // thread. It returns false if it is unable to do the collection due
733 // to the GC locker being active, true otherwise
734 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
735
736 G1HeapVerifier::G1VerifyType young_collection_verify_type() const;
737 void verify_before_young_collection(G1HeapVerifier::G1VerifyType type);
738 void verify_after_young_collection(G1HeapVerifier::G1VerifyType type);
739
740 void calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms);
741
742 // Actually do the work of evacuating the parts of the collection set.
743 void evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states);
744 void evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states);
745 // Evacuate the next set of optional regions.
746 void evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states);
747
748 void pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info);
749 void post_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss);
750
751 void expand_heap_after_young_collection();
752 // Update object copying statistics.
753 void record_obj_copy_mem_stats();
754
755 // The hot card cache for remembered set insertion optimization.
756 G1HotCardCache* _hot_card_cache;
757
758 // The g1 remembered set of the heap.
759 G1RemSet* _rem_set;
760
761 // A set of cards that cover the objects for which the Rsets should be updated
762 // concurrently after the collection.
763 G1DirtyCardQueueSet _dirty_card_queue_set;
764
765 // After a collection pause, convert the regions in the collection set into free
766 // regions.
767 void free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words);
768
769 // Abandon the current collection set without recording policy
770 // statistics or updating free lists.
771 void abandon_collection_set(G1CollectionSet* collection_set);
772
773 // The concurrent marker (and the thread it runs in.)
774 G1ConcurrentMark* _cm;
775 G1ConcurrentMarkThread* _cm_thread;
776
777 // The concurrent refiner.
778 G1ConcurrentRefine* _cr;
779
780 // The parallel task queues
781 RefToScanQueueSet *_task_queues;
782
783 // True iff a evacuation has failed in the current collection.
784 bool _evacuation_failed;
785
786 EvacuationFailedInfo* _evacuation_failed_info_array;
787
788 // Failed evacuations cause some logical from-space objects to have
789 // forwarding pointers to themselves. Reset them.
790 void remove_self_forwarding_pointers();
791
792 // Restore the objects in the regions in the collection set after an
793 // evacuation failure.
794 void restore_after_evac_failure();
795
796 PreservedMarksSet _preserved_marks_set;
797
798 // Preserve the mark of "obj", if necessary, in preparation for its mark
799 // word being overwritten with a self-forwarding-pointer.
800 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m);
801
802 #ifndef PRODUCT
803 // Support for forcing evacuation failures. Analogous to
804 // PromotionFailureALot for the other collectors.
805
806 // Records whether G1EvacuationFailureALot should be in effect
807 // for the current GC
808 bool _evacuation_failure_alot_for_current_gc;
809
810 // Used to record the GC number for interval checking when
811 // determining whether G1EvaucationFailureALot is in effect
812 // for the current GC.
813 size_t _evacuation_failure_alot_gc_number;
814
815 // Count of the number of evacuations between failures.
816 volatile size_t _evacuation_failure_alot_count;
817
818 // Set whether G1EvacuationFailureALot should be in effect
819 // for the current GC (based upon the type of GC and which
820 // command line flags are set);
821 inline bool evacuation_failure_alot_for_gc_type(bool for_young_gc,
822 bool during_initial_mark,
823 bool mark_or_rebuild_in_progress);
824
825 inline void set_evacuation_failure_alot_for_current_gc();
826
827 // Return true if it's time to cause an evacuation failure.
828 inline bool evacuation_should_fail();
829
830 // Reset the G1EvacuationFailureALot counters. Should be called at
831 // the end of an evacuation pause in which an evacuation failure occurred.
832 inline void reset_evacuation_should_fail();
833 #endif // !PRODUCT
834
835 // ("Weak") Reference processing support.
836 //
837 // G1 has 2 instances of the reference processor class. One
838 // (_ref_processor_cm) handles reference object discovery
839 // and subsequent processing during concurrent marking cycles.
840 //
841 // The other (_ref_processor_stw) handles reference object
842 // discovery and processing during full GCs and incremental
843 // evacuation pauses.
844 //
845 // During an incremental pause, reference discovery will be
846 // temporarily disabled for _ref_processor_cm and will be
847 // enabled for _ref_processor_stw. At the end of the evacuation
848 // pause references discovered by _ref_processor_stw will be
849 // processed and discovery will be disabled. The previous
850 // setting for reference object discovery for _ref_processor_cm
851 // will be re-instated.
852 //
853 // At the start of marking:
854 // * Discovery by the CM ref processor is verified to be inactive
855 // and it's discovered lists are empty.
856 // * Discovery by the CM ref processor is then enabled.
857 //
858 // At the end of marking:
859 // * Any references on the CM ref processor's discovered
860 // lists are processed (possibly MT).
861 //
862 // At the start of full GC we:
863 // * Disable discovery by the CM ref processor and
864 // empty CM ref processor's discovered lists
865 // (without processing any entries).
866 // * Verify that the STW ref processor is inactive and it's
867 // discovered lists are empty.
868 // * Temporarily set STW ref processor discovery as single threaded.
869 // * Temporarily clear the STW ref processor's _is_alive_non_header
870 // field.
871 // * Finally enable discovery by the STW ref processor.
872 //
873 // The STW ref processor is used to record any discovered
874 // references during the full GC.
875 //
876 // At the end of a full GC we:
877 // * Enqueue any reference objects discovered by the STW ref processor
878 // that have non-live referents. This has the side-effect of
879 // making the STW ref processor inactive by disabling discovery.
880 // * Verify that the CM ref processor is still inactive
881 // and no references have been placed on it's discovered
882 // lists (also checked as a precondition during initial marking).
883
884 // The (stw) reference processor...
885 ReferenceProcessor* _ref_processor_stw;
886
887 // During reference object discovery, the _is_alive_non_header
888 // closure (if non-null) is applied to the referent object to
889 // determine whether the referent is live. If so then the
890 // reference object does not need to be 'discovered' and can
891 // be treated as a regular oop. This has the benefit of reducing
892 // the number of 'discovered' reference objects that need to
893 // be processed.
894 //
895 // Instance of the is_alive closure for embedding into the
896 // STW reference processor as the _is_alive_non_header field.
897 // Supplying a value for the _is_alive_non_header field is
898 // optional but doing so prevents unnecessary additions to
899 // the discovered lists during reference discovery.
900 G1STWIsAliveClosure _is_alive_closure_stw;
901
902 G1STWSubjectToDiscoveryClosure _is_subject_to_discovery_stw;
903
904 // The (concurrent marking) reference processor...
905 ReferenceProcessor* _ref_processor_cm;
906
907 // Instance of the concurrent mark is_alive closure for embedding
908 // into the Concurrent Marking reference processor as the
909 // _is_alive_non_header field. Supplying a value for the
910 // _is_alive_non_header field is optional but doing so prevents
911 // unnecessary additions to the discovered lists during reference
912 // discovery.
913 G1CMIsAliveClosure _is_alive_closure_cm;
914
915 G1CMSubjectToDiscoveryClosure _is_subject_to_discovery_cm;
916 public:
917
918 RefToScanQueue *task_queue(uint i) const;
919
920 uint num_task_queues() const;
921
922 // A set of cards where updates happened during the GC
923 G1DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
924
925 // Create a G1CollectedHeap with the specified policy.
926 // Must call the initialize method afterwards.
927 // May not return if something goes wrong.
928 G1CollectedHeap(G1CollectorPolicy* policy);
929
930 private:
931 jint initialize_concurrent_refinement();
932 jint initialize_young_gen_sampling_thread();
933 public:
934 // Initialize the G1CollectedHeap to have the initial and
935 // maximum sizes and remembered and barrier sets
936 // specified by the policy object.
937 jint initialize();
938
939 virtual void stop();
940 virtual void safepoint_synchronize_begin();
941 virtual void safepoint_synchronize_end();
942
943 // Return the (conservative) maximum heap alignment for any G1 heap
944 static size_t conservative_max_heap_alignment();
945
946 // Does operations required after initialization has been done.
947 void post_initialize();
948
949 // Initialize weak reference processing.
950 void ref_processing_init();
951
952 virtual Name kind() const {
953 return CollectedHeap::G1;
954 }
955
956 virtual const char* name() const {
957 return "G1";
958 }
959
960 const G1CollectorState* collector_state() const { return &_collector_state; }
961 G1CollectorState* collector_state() { return &_collector_state; }
962
963 // The current policy object for the collector.
964 G1Policy* policy() const { return _policy; }
965 // The remembered set.
966 G1RemSet* rem_set() const { return _rem_set; }
967
968 inline G1GCPhaseTimes* phase_times() const;
969
970 HeapRegionManager* hrm() const { return _hrm; }
971
972 const G1CollectionSet* collection_set() const { return &_collection_set; }
973 G1CollectionSet* collection_set() { return &_collection_set; }
974
975 virtual CollectorPolicy* collector_policy() const;
976
977 virtual SoftRefPolicy* soft_ref_policy();
978
979 virtual void initialize_serviceability();
980 virtual MemoryUsage memory_usage();
981 virtual GrowableArray<GCMemoryManager*> memory_managers();
982 virtual GrowableArray<MemoryPool*> memory_pools();
983
984 // Try to minimize the remembered set.
985 void scrub_rem_set();
986
987 // Apply the given closure on all cards in the Hot Card Cache, emptying it.
988 void iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_i);
989
990 // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it.
991 void iterate_dirty_card_closure(G1CardTableEntryClosure* cl, uint worker_i);
992
993 // The shared block offset table array.
994 G1BlockOffsetTable* bot() const { return _bot; }
995
996 // Reference Processing accessors
997
998 // The STW reference processor....
999 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1000
1001 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; }
1002
1003 // The Concurrent Marking reference processor...
1004 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1005
1006 size_t unused_committed_regions_in_bytes() const;
1007 virtual size_t capacity() const;
1008 virtual size_t used() const;
1009 // This should be called when we're not holding the heap lock. The
1010 // result might be a bit inaccurate.
1011 size_t used_unlocked() const;
1012 size_t recalculate_used() const;
1013
1014 // These virtual functions do the actual allocation.
1015 // Some heaps may offer a contiguous region for shared non-blocking
1016 // allocation, via inlined code (by exporting the address of the top and
1017 // end fields defining the extent of the contiguous allocation region.)
1018 // But G1CollectedHeap doesn't yet support this.
1019
1020 virtual bool is_maximal_no_gc() const {
1021 return _hrm->available() == 0;
1022 }
1023
1024 // Returns whether there are any regions left in the heap for allocation.
1025 bool has_regions_left_for_allocation() const {
1026 return !is_maximal_no_gc() || num_free_regions() != 0;
1027 }
1028
1029 // The current number of regions in the heap.
1030 uint num_regions() const { return _hrm->length(); }
1031
1032 // The max number of regions in the heap.
1033 uint max_regions() const { return _hrm->max_length(); }
1034
1035 // Max number of regions that can be comitted.
1036 uint max_expandable_regions() const { return _hrm->max_expandable_length(); }
1037
1038 // The number of regions that are completely free.
1039 uint num_free_regions() const { return _hrm->num_free_regions(); }
1040
1041 // The number of regions that can be allocated into.
1042 uint num_free_or_available_regions() const { return num_free_regions() + _hrm->available(); }
1043
1044 MemoryUsage get_auxiliary_data_memory_usage() const {
1045 return _hrm->get_auxiliary_data_memory_usage();
1046 }
1047
1048 // The number of regions that are not completely free.
1049 uint num_used_regions() const { return num_regions() - num_free_regions(); }
1050
1051 #ifdef ASSERT
1052 bool is_on_master_free_list(HeapRegion* hr) {
1053 return _hrm->is_free(hr);
1054 }
1055 #endif // ASSERT
1056
1057 inline void old_set_add(HeapRegion* hr);
1058 inline void old_set_remove(HeapRegion* hr);
1059
1060 inline void archive_set_add(HeapRegion* hr);
1061
1062 size_t non_young_capacity_bytes() {
1063 return (old_regions_count() + _archive_set.length() + humongous_regions_count()) * HeapRegion::GrainBytes;
1064 }
1065
1066 // Determine whether the given region is one that we are using as an
1067 // old GC alloc region.
1068 bool is_old_gc_alloc_region(HeapRegion* hr);
1069
1070 // Perform a collection of the heap; intended for use in implementing
1071 // "System.gc". This probably implies as full a collection as the
1072 // "CollectedHeap" supports.
1073 virtual void collect(GCCause::Cause cause);
1074
1075 // Perform a collection of the heap with the given cause; if the VM operation
1076 // fails to execute for any reason, retry only if retry_on_gc_failure is set.
1077 // Returns whether this collection actually executed.
1078 bool try_collect(GCCause::Cause cause, bool retry_on_gc_failure);
1079
1080 // True iff an evacuation has failed in the most-recent collection.
1081 bool evacuation_failed() { return _evacuation_failed; }
1082
1083 void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed);
1084 void prepend_to_freelist(FreeRegionList* list);
1085 void decrement_summary_bytes(size_t bytes);
1086
1087 virtual bool is_in(const void* p) const;
1088 #ifdef ASSERT
1089 // Returns whether p is in one of the available areas of the heap. Slow but
1090 // extensive version.
1091 bool is_in_exact(const void* p) const;
1092 #endif
1093
1094 // Return "TRUE" iff the given object address is within the collection
1095 // set. Assumes that the reference points into the heap.
1096 inline bool is_in_cset(const HeapRegion *hr);
1097 inline bool is_in_cset(oop obj);
1098 inline bool is_in_cset(HeapWord* addr);
1099
1100 inline bool is_in_cset_or_humongous(const oop obj);
1101
1102 private:
1103 // This array is used for a quick test on whether a reference points into
1104 // the collection set or not. Each of the array's elements denotes whether the
1105 // corresponding region is in the collection set or not.
1106 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test;
1107
1108 public:
1109
1110 inline InCSetState in_cset_state(const oop obj);
1111
1112 // Return "TRUE" iff the given object address is in the reserved
1113 // region of g1.
1114 bool is_in_g1_reserved(const void* p) const {
1115 return _hrm->reserved().contains(p);
1116 }
1117
1118 // Returns a MemRegion that corresponds to the space that has been
1119 // reserved for the heap
1120 MemRegion g1_reserved() const {
1121 return _hrm->reserved();
1122 }
1123
1124 virtual bool is_in_closed_subset(const void* p) const;
1125
1126 G1HotCardCache* g1_hot_card_cache() const { return _hot_card_cache; }
1127
1128 G1CardTable* card_table() const {
1129 return _card_table;
1130 }
1131
1132 // Iteration functions.
1133
1134 // Iterate over all objects, calling "cl.do_object" on each.
1135 virtual void object_iterate(ObjectClosure* cl);
1136
1137 virtual void safe_object_iterate(ObjectClosure* cl) {
1138 object_iterate(cl);
1139 }
1140
1141 // Iterate over heap regions, in address order, terminating the
1142 // iteration early if the "do_heap_region" method returns "true".
1143 void heap_region_iterate(HeapRegionClosure* blk) const;
1144
1145 // Return the region with the given index. It assumes the index is valid.
1146 inline HeapRegion* region_at(uint index) const;
1147 inline HeapRegion* region_at_or_null(uint index) const;
1148
1149 // Return the next region (by index) that is part of the same
1150 // humongous object that hr is part of.
1151 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const;
1152
1153 // Calculate the region index of the given address. Given address must be
1154 // within the heap.
1155 inline uint addr_to_region(HeapWord* addr) const;
1156
1157 inline HeapWord* bottom_addr_for_region(uint index) const;
1158
1159 // Two functions to iterate over the heap regions in parallel. Threads
1160 // compete using the HeapRegionClaimer to claim the regions before
1161 // applying the closure on them.
1162 // The _from_worker_offset version uses the HeapRegionClaimer and
1163 // the worker id to calculate a start offset to prevent all workers to
1164 // start from the point.
1165 void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
1166 HeapRegionClaimer* hrclaimer,
1167 uint worker_id) const;
1168
1169 void heap_region_par_iterate_from_start(HeapRegionClosure* cl,
1170 HeapRegionClaimer* hrclaimer) const;
1171
1172 // Iterate over the regions (if any) in the current collection set.
1173 void collection_set_iterate(HeapRegionClosure* blk);
1174
1175 // Iterate over the regions (if any) in the current collection set. Starts the
1176 // iteration over the entire collection set so that the start regions of a given
1177 // worker id over the set active_workers are evenly spread across the set of
1178 // collection set regions.
1179 void collection_set_iterate_from(HeapRegionClosure *blk, uint worker_id);
1180
1181 // Returns the HeapRegion that contains addr. addr must not be NULL.
1182 template <class T>
1183 inline HeapRegion* heap_region_containing(const T addr) const;
1184
1185 // Returns the HeapRegion that contains addr, or NULL if that is an uncommitted
1186 // region. addr must not be NULL.
1187 template <class T>
1188 inline HeapRegion* heap_region_containing_or_null(const T addr) const;
1189
1190 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1191 // each address in the (reserved) heap is a member of exactly
1192 // one block. The defining characteristic of a block is that it is
1193 // possible to find its size, and thus to progress forward to the next
1194 // block. (Blocks may be of different sizes.) Thus, blocks may
1195 // represent Java objects, or they might be free blocks in a
1196 // free-list-based heap (or subheap), as long as the two kinds are
1197 // distinguishable and the size of each is determinable.
1198
1199 // Returns the address of the start of the "block" that contains the
1200 // address "addr". We say "blocks" instead of "object" since some heaps
1201 // may not pack objects densely; a chunk may either be an object or a
1202 // non-object.
1203 virtual HeapWord* block_start(const void* addr) const;
1204
1205 // Requires "addr" to be the start of a chunk, and returns its size.
1206 // "addr + size" is required to be the start of a new chunk, or the end
1207 // of the active area of the heap.
1208 virtual size_t block_size(const HeapWord* addr) const;
1209
1210 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1211 // the block is an object.
1212 virtual bool block_is_obj(const HeapWord* addr) const;
1213
1214 // Section on thread-local allocation buffers (TLABs)
1215 // See CollectedHeap for semantics.
1216
1217 bool supports_tlab_allocation() const;
1218 size_t tlab_capacity(Thread* ignored) const;
1219 size_t tlab_used(Thread* ignored) const;
1220 size_t max_tlab_size() const;
1221 size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1222
1223 inline bool is_in_young(const oop obj);
1224
1225 // Returns "true" iff the given word_size is "very large".
1226 static bool is_humongous(size_t word_size) {
1227 // Note this has to be strictly greater-than as the TLABs
1228 // are capped at the humongous threshold and we want to
1229 // ensure that we don't try to allocate a TLAB as
1230 // humongous and that we don't allocate a humongous
1231 // object in a TLAB.
1232 return word_size > _humongous_object_threshold_in_words;
1233 }
1234
1235 // Returns the humongous threshold for a specific region size
1236 static size_t humongous_threshold_for(size_t region_size) {
1237 return (region_size / 2);
1238 }
1239
1240 // Returns the number of regions the humongous object of the given word size
1241 // requires.
1242 static size_t humongous_obj_size_in_regions(size_t word_size);
1243
1244 // Print the maximum heap capacity.
1245 virtual size_t max_capacity() const;
1246
1247 // Return the size of reserved memory. Returns different value than max_capacity() when AllocateOldGenAt is used.
1248 virtual size_t max_reserved_capacity() const;
1249
1250 virtual jlong millis_since_last_gc();
1251
1252
1253 // Convenience function to be used in situations where the heap type can be
1254 // asserted to be this type.
1255 static G1CollectedHeap* heap();
1256
1257 void set_region_short_lived_locked(HeapRegion* hr);
1258 // add appropriate methods for any other surv rate groups
1259
1260 const G1SurvivorRegions* survivor() const { return &_survivor; }
1261
1262 uint eden_regions_count() const { return _eden.length(); }
1263 uint survivor_regions_count() const { return _survivor.length(); }
1264 uint young_regions_count() const { return _eden.length() + _survivor.length(); }
1265 uint old_regions_count() const { return _old_set.length(); }
1266 uint archive_regions_count() const { return _archive_set.length(); }
1267 uint humongous_regions_count() const { return _humongous_set.length(); }
1268
1269 #ifdef ASSERT
1270 bool check_young_list_empty();
1271 #endif
1272
1273 // *** Stuff related to concurrent marking. It's not clear to me that so
1274 // many of these need to be public.
1275
1276 // The functions below are helper functions that a subclass of
1277 // "CollectedHeap" can use in the implementation of its virtual
1278 // functions.
1279 // This performs a concurrent marking of the live objects in a
1280 // bitmap off to the side.
1281 void do_concurrent_mark();
1282
1283 bool is_marked_next(oop obj) const;
1284
1285 // Determine if an object is dead, given the object and also
1286 // the region to which the object belongs. An object is dead
1287 // iff a) it was not allocated since the last mark, b) it
1288 // is not marked, and c) it is not in an archive region.
1289 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1290 return
1291 hr->is_obj_dead(obj, _cm->prev_mark_bitmap()) &&
1292 !hr->is_archive();
1293 }
1294
1295 // This function returns true when an object has been
1296 // around since the previous marking and hasn't yet
1297 // been marked during this marking, and is not in an archive region.
1298 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1299 return
1300 !hr->obj_allocated_since_next_marking(obj) &&
1301 !is_marked_next(obj) &&
1302 !hr->is_archive();
1303 }
1304
1305 // Determine if an object is dead, given only the object itself.
1306 // This will find the region to which the object belongs and
1307 // then call the region version of the same function.
1308
1309 // Added if it is NULL it isn't dead.
1310
1311 inline bool is_obj_dead(const oop obj) const;
1312
1313 inline bool is_obj_ill(const oop obj) const;
1314
1315 inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const;
1316 inline bool is_obj_dead_full(const oop obj) const;
1317
1318 G1ConcurrentMark* concurrent_mark() const { return _cm; }
1319
1320 // Refinement
1321
1322 G1ConcurrentRefine* concurrent_refine() const { return _cr; }
1323
1324 // Optimized nmethod scanning support routines
1325
1326 // Is an oop scavengeable
1327 virtual bool is_scavengable(oop obj);
1328
1329 // Register the given nmethod with the G1 heap.
1330 virtual void register_nmethod(nmethod* nm);
1331
1332 // Unregister the given nmethod from the G1 heap.
1333 virtual void unregister_nmethod(nmethod* nm);
1334
1335 // Free up superfluous code root memory.
1336 void purge_code_root_memory();
1337
1338 // Rebuild the strong code root lists for each region
1339 // after a full GC.
1340 void rebuild_strong_code_roots();
1341
1342 // Partial cleaning of VM internal data structures.
1343 void string_dedup_cleaning(BoolObjectClosure* is_alive,
1344 OopClosure* keep_alive,
1345 G1GCPhaseTimes* phase_times = NULL);
1346
1347 // Performs cleaning of data structures after class unloading.
1348 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred);
1349
1350 // Redirty logged cards in the refinement queue.
1351 void redirty_logged_cards();
1352 // Verification
1353
1354 // Deduplicate the string
1355 virtual void deduplicate_string(oop str);
1356
1357 // Perform any cleanup actions necessary before allowing a verification.
1358 virtual void prepare_for_verify();
1359
1360 // Perform verification.
1361
1362 // vo == UsePrevMarking -> use "prev" marking information,
1363 // vo == UseNextMarking -> use "next" marking information
1364 // vo == UseFullMarking -> use "next" marking bitmap but no TAMS
1365 //
1366 // NOTE: Only the "prev" marking information is guaranteed to be
1367 // consistent most of the time, so most calls to this should use
1368 // vo == UsePrevMarking.
1369 // Currently, there is only one case where this is called with
1370 // vo == UseNextMarking, which is to verify the "next" marking
1371 // information at the end of remark.
1372 // Currently there is only one place where this is called with
1373 // vo == UseFullMarking, which is to verify the marking during a
1374 // full GC.
1375 void verify(VerifyOption vo);
1376
1377 // WhiteBox testing support.
1378 virtual bool supports_concurrent_phase_control() const;
1379 virtual bool request_concurrent_phase(const char* phase);
1380 bool is_heterogeneous_heap() const;
1381
1382 virtual WorkGang* get_safepoint_workers() { return _workers; }
1383
1384 // The methods below are here for convenience and dispatch the
1385 // appropriate method depending on value of the given VerifyOption
1386 // parameter. The values for that parameter, and their meanings,
1387 // are the same as those above.
1388
1389 bool is_obj_dead_cond(const oop obj,
1390 const HeapRegion* hr,
1391 const VerifyOption vo) const;
1392
1393 bool is_obj_dead_cond(const oop obj,
1394 const VerifyOption vo) const;
1395
1396 G1HeapSummary create_g1_heap_summary();
1397 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats);
1398
1399 // Printing
1400 private:
1401 void print_heap_regions() const;
1402 void print_regions_on(outputStream* st) const;
1403
1404 public:
1405 virtual void print_on(outputStream* st) const;
1406 virtual void print_extended_on(outputStream* st) const;
1407 virtual void print_on_error(outputStream* st) const;
1408
1409 virtual void print_gc_threads_on(outputStream* st) const;
1410 virtual void gc_threads_do(ThreadClosure* tc) const;
1411
1412 // Override
1413 void print_tracing_info() const;
1414
1415 // The following two methods are helpful for debugging RSet issues.
1416 void print_cset_rsets() PRODUCT_RETURN;
1417 void print_all_rsets() PRODUCT_RETURN;
1418
1419 size_t pending_card_num();
1420 };
1421
1422 class G1ParEvacuateFollowersClosure : public VoidClosure {
1423 private:
1424 double _start_term;
1425 double _term_time;
1426 size_t _term_attempts;
1427
1428 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
1429 void end_term_time() { _term_time += (os::elapsedTime() - _start_term); }
1430 protected:
1431 G1CollectedHeap* _g1h;
1432 G1ParScanThreadState* _par_scan_state;
1433 RefToScanQueueSet* _queues;
1434 ParallelTaskTerminator* _terminator;
1435 G1GCPhaseTimes::GCParPhases _phase;
1436
1437 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
1438 RefToScanQueueSet* queues() { return _queues; }
1439 ParallelTaskTerminator* terminator() { return _terminator; }
1440
1441 public:
1442 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
1443 G1ParScanThreadState* par_scan_state,
1444 RefToScanQueueSet* queues,
1445 ParallelTaskTerminator* terminator,
1446 G1GCPhaseTimes::GCParPhases phase)
1447 : _start_term(0.0), _term_time(0.0), _term_attempts(0),
1448 _g1h(g1h), _par_scan_state(par_scan_state),
1449 _queues(queues), _terminator(terminator), _phase(phase) {}
1450
1451 void do_void();
1452
1453 double term_time() const { return _term_time; }
1454 size_t term_attempts() const { return _term_attempts; }
1455
1456 private:
1457 inline bool offer_termination();
1458 };
1459
1460 #endif // SHARE_GC_G1_G1COLLECTEDHEAP_HPP