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.
4 *
5 * This code is free software; you can redistribute it and/or modify it
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
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24
25 #ifndef SHARE_GC_G1_G1COLLECTEDHEAP_HPP
26 #define SHARE_GC_G1_G1COLLECTEDHEAP_HPP
27
28 #include "gc/g1/g1BarrierSet.hpp"
29 #include "gc/g1/g1BiasedArray.hpp"
30 #include "gc/g1/g1CardTable.hpp"
31 #include "gc/g1/g1CollectionSet.hpp"
32 #include "gc/g1/g1CollectorState.hpp"
33 #include "gc/g1/g1ConcurrentMark.hpp"
34 #include "gc/g1/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 volatile 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 #define assert_used_and_recalculate_used(g1h) \
360 do { \
361 size_t cur_used_bytes = g1h->used(); \
362 size_t recal_used_bytes = g1h->recalculate_used(); \
363 assert(cur_used_bytes == recal_used_bytes, "Used(" SIZE_FORMAT ") is not" \
364 " same as recalculated used(" SIZE_FORMAT ").", \
365 cur_used_bytes, recal_used_bytes); \
366 } while (0)
367
368 const char* young_gc_name() const;
369
370 // The young region list.
371 G1EdenRegions _eden;
372 G1SurvivorRegions _survivor;
373
374 STWGCTimer* _gc_timer_stw;
375
376 G1NewTracer* _gc_tracer_stw;
377
378 // The current policy object for the collector.
379 G1Policy* _policy;
380 G1HeapSizingPolicy* _heap_sizing_policy;
381
382 G1CollectionSet _collection_set;
383
384 // Try to allocate a single non-humongous HeapRegion sufficient for
385 // an allocation of the given word_size. If do_expand is true,
386 // attempt to expand the heap if necessary to satisfy the allocation
387 // request. 'type' takes the type of region to be allocated. (Use constants
388 // Old, Eden, Humongous, Survivor defined in HeapRegionType.)
389 HeapRegion* new_region(size_t word_size, HeapRegionType type, bool do_expand);
390
391 // Initialize a contiguous set of free regions of length num_regions
392 // and starting at index first so that they appear as a single
393 // humongous region.
394 HeapWord* humongous_obj_allocate_initialize_regions(uint first,
395 uint num_regions,
396 size_t word_size);
397
398 // Attempt to allocate a humongous object of the given size. Return
399 // NULL if unsuccessful.
400 HeapWord* humongous_obj_allocate(size_t word_size);
401
402 // The following two methods, allocate_new_tlab() and
403 // mem_allocate(), are the two main entry points from the runtime
404 // into the G1's allocation routines. They have the following
405 // assumptions:
406 //
407 // * They should both be called outside safepoints.
408 //
409 // * They should both be called without holding the Heap_lock.
410 //
411 // * All allocation requests for new TLABs should go to
412 // allocate_new_tlab().
413 //
414 // * All non-TLAB allocation requests should go to mem_allocate().
415 //
416 // * If either call cannot satisfy the allocation request using the
417 // current allocating region, they will try to get a new one. If
418 // this fails, they will attempt to do an evacuation pause and
419 // retry the allocation.
420 //
421 // * If all allocation attempts fail, even after trying to schedule
422 // an evacuation pause, allocate_new_tlab() will return NULL,
423 // whereas mem_allocate() will attempt a heap expansion and/or
424 // schedule a Full GC.
425 //
426 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
427 // should never be called with word_size being humongous. All
428 // humongous allocation requests should go to mem_allocate() which
429 // will satisfy them with a special path.
430
431 virtual HeapWord* allocate_new_tlab(size_t min_size,
432 size_t requested_size,
433 size_t* actual_size);
434
435 virtual HeapWord* mem_allocate(size_t word_size,
436 bool* gc_overhead_limit_was_exceeded);
437
438 // First-level mutator allocation attempt: try to allocate out of
439 // the mutator alloc region without taking the Heap_lock. This
440 // should only be used for non-humongous allocations.
441 inline HeapWord* attempt_allocation(size_t min_word_size,
442 size_t desired_word_size,
443 size_t* actual_word_size);
444
445 // Second-level mutator allocation attempt: take the Heap_lock and
446 // retry the allocation attempt, potentially scheduling a GC
447 // pause. This should only be used for non-humongous allocations.
448 HeapWord* attempt_allocation_slow(size_t word_size);
449
450 // Takes the Heap_lock and attempts a humongous allocation. It can
451 // potentially schedule a GC pause.
452 HeapWord* attempt_allocation_humongous(size_t word_size);
453
454 // Allocation attempt that should be called during safepoints (e.g.,
455 // at the end of a successful GC). expect_null_mutator_alloc_region
456 // specifies whether the mutator alloc region is expected to be NULL
457 // or not.
458 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
459 bool expect_null_mutator_alloc_region);
460
461 // These methods are the "callbacks" from the G1AllocRegion class.
462
463 // For mutator alloc regions.
464 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
465 void retire_mutator_alloc_region(HeapRegion* alloc_region,
466 size_t allocated_bytes);
467
468 // For GC alloc regions.
469 bool has_more_regions(InCSetState dest);
470 HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest);
471 void retire_gc_alloc_region(HeapRegion* alloc_region,
472 size_t allocated_bytes, InCSetState dest);
473
474 // - if explicit_gc is true, the GC is for a System.gc() etc,
475 // otherwise it's for a failed allocation.
476 // - if clear_all_soft_refs is true, all soft references should be
477 // cleared during the GC.
478 // - it returns false if it is unable to do the collection due to the
479 // GC locker being active, true otherwise.
480 bool do_full_collection(bool explicit_gc,
481 bool clear_all_soft_refs);
482
483 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread.
484 virtual void do_full_collection(bool clear_all_soft_refs);
485
486 // Callback from VM_G1CollectForAllocation operation.
487 // This function does everything necessary/possible to satisfy a
488 // failed allocation request (including collection, expansion, etc.)
489 HeapWord* satisfy_failed_allocation(size_t word_size,
490 bool* succeeded);
491 // Internal helpers used during full GC to split it up to
492 // increase readability.
493 void abort_concurrent_cycle();
494 void verify_before_full_collection(bool explicit_gc);
495 void prepare_heap_for_full_collection();
496 void prepare_heap_for_mutators();
497 void abort_refinement();
498 void verify_after_full_collection();
499 void print_heap_after_full_collection(G1HeapTransition* heap_transition);
500
501 // Helper method for satisfy_failed_allocation()
502 HeapWord* satisfy_failed_allocation_helper(size_t word_size,
503 bool do_gc,
504 bool clear_all_soft_refs,
505 bool expect_null_mutator_alloc_region,
506 bool* gc_succeeded);
507
508 // Attempting to expand the heap sufficiently
509 // to support an allocation of the given "word_size". If
510 // successful, perform the allocation and return the address of the
511 // allocated block, or else "NULL".
512 HeapWord* expand_and_allocate(size_t word_size);
513
514 // Process any reference objects discovered.
515 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states);
516
517 // If during an initial mark pause we may install a pending list head which is not
518 // otherwise reachable ensure that it is marked in the bitmap for concurrent marking
519 // to discover.
520 void make_pending_list_reachable();
521
522 // Merges the information gathered on a per-thread basis for all worker threads
523 // during GC into global variables.
524 void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states);
525 public:
526 G1YoungRemSetSamplingThread* sampling_thread() const { return _young_gen_sampling_thread; }
527
528 WorkGang* workers() const { return _workers; }
529
530 // Runs the given AbstractGangTask with the current active workers, returning the
531 // total time taken.
532 Tickspan run_task(AbstractGangTask* task);
533
534 G1Allocator* allocator() {
535 return _allocator;
536 }
537
538 G1HeapVerifier* verifier() {
539 return _verifier;
540 }
541
542 G1MonitoringSupport* g1mm() {
543 assert(_g1mm != NULL, "should have been initialized");
544 return _g1mm;
545 }
546
547 void resize_heap_if_necessary();
548
549 // Expand the garbage-first heap by at least the given size (in bytes!).
550 // Returns true if the heap was expanded by the requested amount;
551 // false otherwise.
552 // (Rounds up to a HeapRegion boundary.)
553 bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL);
554
555 // Returns the PLAB statistics for a given destination.
556 inline G1EvacStats* alloc_buffer_stats(InCSetState dest);
557
558 // Determines PLAB size for a given destination.
559 inline size_t desired_plab_sz(InCSetState dest);
560
561 // Do anything common to GC's.
562 void gc_prologue(bool full);
563 void gc_epilogue(bool full);
564
565 // Does the given region fulfill remembered set based eager reclaim candidate requirements?
566 bool is_potential_eager_reclaim_candidate(HeapRegion* r) const;
567
568 // Modify the reclaim candidate set and test for presence.
569 // These are only valid for starts_humongous regions.
570 inline void set_humongous_reclaim_candidate(uint region, bool value);
571 inline bool is_humongous_reclaim_candidate(uint region);
572
573 // Remove from the reclaim candidate set. Also remove from the
574 // collection set so that later encounters avoid the slow path.
575 inline void set_humongous_is_live(oop obj);
576
577 // Register the given region to be part of the collection set.
578 inline void register_humongous_region_with_cset(uint index);
579 // Register regions with humongous objects (actually on the start region) in
580 // the in_cset_fast_test table.
581 void register_humongous_regions_with_cset();
582 // We register a region with the fast "in collection set" test. We
583 // simply set to true the array slot corresponding to this region.
584 void register_young_region_with_cset(HeapRegion* r) {
585 _in_cset_fast_test.set_in_young(r->hrm_index());
586 }
587 void register_old_region_with_cset(HeapRegion* r) {
588 _in_cset_fast_test.set_in_old(r->hrm_index());
589 }
590 void register_optional_region_with_cset(HeapRegion* r) {
591 _in_cset_fast_test.set_optional(r->hrm_index());
592 }
593 void clear_in_cset(const HeapRegion* hr) {
594 _in_cset_fast_test.clear(hr);
595 }
596
597 void clear_cset_fast_test() {
598 _in_cset_fast_test.clear();
599 }
600
601 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause);
602
603 // This is called at the start of either a concurrent cycle or a Full
604 // GC to update the number of old marking cycles started.
605 void increment_old_marking_cycles_started();
606
607 // This is called at the end of either a concurrent cycle or a Full
608 // GC to update the number of old marking cycles completed. Those two
609 // can happen in a nested fashion, i.e., we start a concurrent
610 // cycle, a Full GC happens half-way through it which ends first,
611 // and then the cycle notices that a Full GC happened and ends
612 // too. The concurrent parameter is a boolean to help us do a bit
613 // tighter consistency checking in the method. If concurrent is
614 // false, the caller is the inner caller in the nesting (i.e., the
615 // Full GC). If concurrent is true, the caller is the outer caller
616 // in this nesting (i.e., the concurrent cycle). Further nesting is
617 // not currently supported. The end of this call also notifies
618 // the FullGCCount_lock in case a Java thread is waiting for a full
619 // GC to happen (e.g., it called System.gc() with
620 // +ExplicitGCInvokesConcurrent).
621 void increment_old_marking_cycles_completed(bool concurrent);
622
623 uint old_marking_cycles_completed() {
624 return _old_marking_cycles_completed;
625 }
626
627 G1HRPrinter* hr_printer() { return &_hr_printer; }
628
629 // Allocates a new heap region instance.
630 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr);
631
632 // Allocate the highest free region in the reserved heap. This will commit
633 // regions as necessary.
634 HeapRegion* alloc_highest_free_region();
635
636 // Frees a non-humongous region by initializing its contents and
637 // adding it to the free list that's passed as a parameter (this is
638 // usually a local list which will be appended to the master free
639 // list later). The used bytes of freed regions are accumulated in
640 // pre_used. If skip_remset is true, the region's RSet will not be freed
641 // up. If skip_hot_card_cache is true, the region's hot card cache will not
642 // be freed up. The assumption is that this will be done later.
643 // The locked parameter indicates if the caller has already taken
644 // care of proper synchronization. This may allow some optimizations.
645 void free_region(HeapRegion* hr,
646 FreeRegionList* free_list,
647 bool skip_remset,
648 bool skip_hot_card_cache = false,
649 bool locked = false);
650
651 // It dirties the cards that cover the block so that the post
652 // write barrier never queues anything when updating objects on this
653 // block. It is assumed (and in fact we assert) that the block
654 // belongs to a young region.
655 inline void dirty_young_block(HeapWord* start, size_t word_size);
656
657 // Frees a humongous region by collapsing it into individual regions
658 // and calling free_region() for each of them. The freed regions
659 // will be added to the free list that's passed as a parameter (this
660 // is usually a local list which will be appended to the master free
661 // list later).
662 // The method assumes that only a single thread is ever calling
663 // this for a particular region at once.
664 void free_humongous_region(HeapRegion* hr,
665 FreeRegionList* free_list);
666
667 // Facility for allocating in 'archive' regions in high heap memory and
668 // recording the allocated ranges. These should all be called from the
669 // VM thread at safepoints, without the heap lock held. They can be used
670 // to create and archive a set of heap regions which can be mapped at the
671 // same fixed addresses in a subsequent JVM invocation.
672 void begin_archive_alloc_range(bool open = false);
673
674 // Check if the requested size would be too large for an archive allocation.
675 bool is_archive_alloc_too_large(size_t word_size);
676
677 // Allocate memory of the requested size from the archive region. This will
678 // return NULL if the size is too large or if no memory is available. It
679 // does not trigger a garbage collection.
680 HeapWord* archive_mem_allocate(size_t word_size);
681
682 // Optionally aligns the end address and returns the allocated ranges in
683 // an array of MemRegions in order of ascending addresses.
684 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
685 size_t end_alignment_in_bytes = 0);
686
687 // Facility for allocating a fixed range within the heap and marking
688 // the containing regions as 'archive'. For use at JVM init time, when the
689 // caller may mmap archived heap data at the specified range(s).
690 // Verify that the MemRegions specified in the argument array are within the
691 // reserved heap.
692 bool check_archive_addresses(MemRegion* range, size_t count);
693
694 // Commit the appropriate G1 regions containing the specified MemRegions
695 // and mark them as 'archive' regions. The regions in the array must be
696 // non-overlapping and in order of ascending address.
697 bool alloc_archive_regions(MemRegion* range, size_t count, bool open);
698
699 // Insert any required filler objects in the G1 regions around the specified
700 // ranges to make the regions parseable. This must be called after
701 // alloc_archive_regions, and after class loading has occurred.
702 void fill_archive_regions(MemRegion* range, size_t count);
703
704 // For each of the specified MemRegions, uncommit the containing G1 regions
705 // which had been allocated by alloc_archive_regions. This should be called
706 // rather than fill_archive_regions at JVM init time if the archive file
707 // mapping failed, with the same non-overlapping and sorted MemRegion array.
708 void dealloc_archive_regions(MemRegion* range, size_t count, bool is_open);
709
710 oop materialize_archived_object(oop obj);
711
712 private:
713
714 // Shrink the garbage-first heap by at most the given size (in bytes!).
715 // (Rounds down to a HeapRegion boundary.)
716 void shrink(size_t expand_bytes);
717 void shrink_helper(size_t expand_bytes);
718
719 #if TASKQUEUE_STATS
720 static void print_taskqueue_stats_hdr(outputStream* const st);
721 void print_taskqueue_stats() const;
722 void reset_taskqueue_stats();
723 #endif // TASKQUEUE_STATS
724
725 // Schedule the VM operation that will do an evacuation pause to
726 // satisfy an allocation request of word_size. *succeeded will
727 // return whether the VM operation was successful (it did do an
728 // evacuation pause) or not (another thread beat us to it or the GC
729 // locker was active). Given that we should not be holding the
730 // Heap_lock when we enter this method, we will pass the
731 // gc_count_before (i.e., total_collections()) as a parameter since
732 // it has to be read while holding the Heap_lock. Currently, both
733 // methods that call do_collection_pause() release the Heap_lock
734 // before the call, so it's easy to read gc_count_before just before.
735 HeapWord* do_collection_pause(size_t word_size,
736 uint gc_count_before,
737 bool* succeeded,
738 GCCause::Cause gc_cause);
739
740 void wait_for_root_region_scanning();
741
742 // The guts of the incremental collection pause, executed by the vm
743 // thread. It returns false if it is unable to do the collection due
744 // to the GC locker being active, true otherwise
745 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
746
747 G1HeapVerifier::G1VerifyType young_collection_verify_type() const;
748 void verify_before_young_collection(G1HeapVerifier::G1VerifyType type);
749 void verify_after_young_collection(G1HeapVerifier::G1VerifyType type);
750
751 void calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms);
752
753 // Actually do the work of evacuating the parts of the collection set.
754 void evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states);
755 void evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states);
756 private:
757 // Evacuate the next set of optional regions.
758 void evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states);
759
760 public:
761 void pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info);
762 void post_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss);
763
764 void expand_heap_after_young_collection();
765 // Update object copying statistics.
766 void record_obj_copy_mem_stats();
767
768 // The hot card cache for remembered set insertion optimization.
769 G1HotCardCache* _hot_card_cache;
770
771 // The g1 remembered set of the heap.
772 G1RemSet* _rem_set;
773
774 // A set of cards that cover the objects for which the Rsets should be updated
775 // concurrently after the collection.
776 G1DirtyCardQueueSet _dirty_card_queue_set;
777
778 // After a collection pause, convert the regions in the collection set into free
779 // regions.
780 void free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words);
781
782 // Abandon the current collection set without recording policy
783 // statistics or updating free lists.
784 void abandon_collection_set(G1CollectionSet* collection_set);
785
786 // The concurrent marker (and the thread it runs in.)
787 G1ConcurrentMark* _cm;
788 G1ConcurrentMarkThread* _cm_thread;
789
790 // The concurrent refiner.
791 G1ConcurrentRefine* _cr;
792
793 // The parallel task queues
794 RefToScanQueueSet *_task_queues;
795
796 // True iff a evacuation has failed in the current collection.
797 bool _evacuation_failed;
798
799 EvacuationFailedInfo* _evacuation_failed_info_array;
800
801 // Failed evacuations cause some logical from-space objects to have
802 // forwarding pointers to themselves. Reset them.
803 void remove_self_forwarding_pointers();
804
805 // Restore the objects in the regions in the collection set after an
806 // evacuation failure.
807 void restore_after_evac_failure();
808
809 PreservedMarksSet _preserved_marks_set;
810
811 // Preserve the mark of "obj", if necessary, in preparation for its mark
812 // word being overwritten with a self-forwarding-pointer.
813 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m);
814
815 #ifndef PRODUCT
816 // Support for forcing evacuation failures. Analogous to
817 // PromotionFailureALot for the other collectors.
818
819 // Records whether G1EvacuationFailureALot should be in effect
820 // for the current GC
821 bool _evacuation_failure_alot_for_current_gc;
822
823 // Used to record the GC number for interval checking when
824 // determining whether G1EvaucationFailureALot is in effect
825 // for the current GC.
826 size_t _evacuation_failure_alot_gc_number;
827
828 // Count of the number of evacuations between failures.
829 volatile size_t _evacuation_failure_alot_count;
830
831 // Set whether G1EvacuationFailureALot should be in effect
832 // for the current GC (based upon the type of GC and which
833 // command line flags are set);
834 inline bool evacuation_failure_alot_for_gc_type(bool for_young_gc,
835 bool during_initial_mark,
836 bool mark_or_rebuild_in_progress);
837
838 inline void set_evacuation_failure_alot_for_current_gc();
839
840 // Return true if it's time to cause an evacuation failure.
841 inline bool evacuation_should_fail();
842
843 // Reset the G1EvacuationFailureALot counters. Should be called at
844 // the end of an evacuation pause in which an evacuation failure occurred.
845 inline void reset_evacuation_should_fail();
846 #endif // !PRODUCT
847
848 // ("Weak") Reference processing support.
849 //
850 // G1 has 2 instances of the reference processor class. One
851 // (_ref_processor_cm) handles reference object discovery
852 // and subsequent processing during concurrent marking cycles.
853 //
854 // The other (_ref_processor_stw) handles reference object
855 // discovery and processing during full GCs and incremental
856 // evacuation pauses.
857 //
858 // During an incremental pause, reference discovery will be
859 // temporarily disabled for _ref_processor_cm and will be
860 // enabled for _ref_processor_stw. At the end of the evacuation
861 // pause references discovered by _ref_processor_stw will be
862 // processed and discovery will be disabled. The previous
863 // setting for reference object discovery for _ref_processor_cm
864 // will be re-instated.
865 //
866 // At the start of marking:
867 // * Discovery by the CM ref processor is verified to be inactive
868 // and it's discovered lists are empty.
869 // * Discovery by the CM ref processor is then enabled.
870 //
871 // At the end of marking:
872 // * Any references on the CM ref processor's discovered
873 // lists are processed (possibly MT).
874 //
875 // At the start of full GC we:
876 // * Disable discovery by the CM ref processor and
877 // empty CM ref processor's discovered lists
878 // (without processing any entries).
879 // * Verify that the STW ref processor is inactive and it's
880 // discovered lists are empty.
881 // * Temporarily set STW ref processor discovery as single threaded.
882 // * Temporarily clear the STW ref processor's _is_alive_non_header
883 // field.
884 // * Finally enable discovery by the STW ref processor.
885 //
886 // The STW ref processor is used to record any discovered
887 // references during the full GC.
888 //
889 // At the end of a full GC we:
890 // * Enqueue any reference objects discovered by the STW ref processor
891 // that have non-live referents. This has the side-effect of
892 // making the STW ref processor inactive by disabling discovery.
893 // * Verify that the CM ref processor is still inactive
894 // and no references have been placed on it's discovered
895 // lists (also checked as a precondition during initial marking).
896
897 // The (stw) reference processor...
898 ReferenceProcessor* _ref_processor_stw;
899
900 // During reference object discovery, the _is_alive_non_header
901 // closure (if non-null) is applied to the referent object to
902 // determine whether the referent is live. If so then the
903 // reference object does not need to be 'discovered' and can
904 // be treated as a regular oop. This has the benefit of reducing
905 // the number of 'discovered' reference objects that need to
906 // be processed.
907 //
908 // Instance of the is_alive closure for embedding into the
909 // STW reference processor as the _is_alive_non_header field.
910 // Supplying a value for the _is_alive_non_header field is
911 // optional but doing so prevents unnecessary additions to
912 // the discovered lists during reference discovery.
913 G1STWIsAliveClosure _is_alive_closure_stw;
914
915 G1STWSubjectToDiscoveryClosure _is_subject_to_discovery_stw;
916
917 // The (concurrent marking) reference processor...
918 ReferenceProcessor* _ref_processor_cm;
919
920 // Instance of the concurrent mark is_alive closure for embedding
921 // into the Concurrent Marking reference processor as the
922 // _is_alive_non_header field. Supplying a value for the
923 // _is_alive_non_header field is optional but doing so prevents
924 // unnecessary additions to the discovered lists during reference
925 // discovery.
926 G1CMIsAliveClosure _is_alive_closure_cm;
927
928 G1CMSubjectToDiscoveryClosure _is_subject_to_discovery_cm;
929 public:
930
931 RefToScanQueue *task_queue(uint i) const;
932
933 uint num_task_queues() const;
934
935 // A set of cards where updates happened during the GC
936 G1DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
937
938 // Create a G1CollectedHeap with the specified policy.
939 // Must call the initialize method afterwards.
940 // May not return if something goes wrong.
941 G1CollectedHeap(G1CollectorPolicy* policy);
942
943 private:
944 jint initialize_concurrent_refinement();
945 jint initialize_young_gen_sampling_thread();
946 public:
947 // Initialize the G1CollectedHeap to have the initial and
948 // maximum sizes and remembered and barrier sets
949 // specified by the policy object.
950 jint initialize();
951
952 virtual void stop();
953 virtual void safepoint_synchronize_begin();
954 virtual void safepoint_synchronize_end();
955
956 // Return the (conservative) maximum heap alignment for any G1 heap
957 static size_t conservative_max_heap_alignment();
958
959 // Does operations required after initialization has been done.
960 void post_initialize();
961
962 // Initialize weak reference processing.
963 void ref_processing_init();
964
965 virtual Name kind() const {
966 return CollectedHeap::G1;
967 }
968
969 virtual const char* name() const {
970 return "G1";
971 }
972
973 const G1CollectorState* collector_state() const { return &_collector_state; }
974 G1CollectorState* collector_state() { return &_collector_state; }
975
976 // The current policy object for the collector.
977 G1Policy* policy() const { return _policy; }
978 // The remembered set.
979 G1RemSet* rem_set() const { return _rem_set; }
980
981 inline G1GCPhaseTimes* phase_times() const;
982
983 HeapRegionManager* hrm() const { return _hrm; }
984
985 const G1CollectionSet* collection_set() const { return &_collection_set; }
986 G1CollectionSet* collection_set() { return &_collection_set; }
987
988 virtual CollectorPolicy* collector_policy() const;
989
990 virtual SoftRefPolicy* soft_ref_policy();
991
992 virtual void initialize_serviceability();
993 virtual MemoryUsage memory_usage();
994 virtual GrowableArray<GCMemoryManager*> memory_managers();
995 virtual GrowableArray<MemoryPool*> memory_pools();
996
997 // Try to minimize the remembered set.
998 void scrub_rem_set();
999
1000 // Apply the given closure on all cards in the Hot Card Cache, emptying it.
1001 void iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_i);
1002
1003 // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it.
1004 void iterate_dirty_card_closure(G1CardTableEntryClosure* cl, uint worker_i);
1005
1006 // The shared block offset table array.
1007 G1BlockOffsetTable* bot() const { return _bot; }
1008
1009 // Reference Processing accessors
1010
1011 // The STW reference processor....
1012 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1013
1014 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; }
1015
1016 // The Concurrent Marking reference processor...
1017 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1018
1019 size_t unused_committed_regions_in_bytes() const;
1020 virtual size_t capacity() const;
1021 virtual size_t used() const;
1022 // This should be called when we're not holding the heap lock. The
1023 // result might be a bit inaccurate.
1024 size_t used_unlocked() const;
1025 size_t recalculate_used() const;
1026
1027 // These virtual functions do the actual allocation.
1028 // Some heaps may offer a contiguous region for shared non-blocking
1029 // allocation, via inlined code (by exporting the address of the top and
1030 // end fields defining the extent of the contiguous allocation region.)
1031 // But G1CollectedHeap doesn't yet support this.
1032
1033 virtual bool is_maximal_no_gc() const {
1034 return _hrm->available() == 0;
1035 }
1036
1037 // Returns whether there are any regions left in the heap for allocation.
1038 bool has_regions_left_for_allocation() const {
1039 return !is_maximal_no_gc() || num_free_regions() != 0;
1040 }
1041
1042 // The current number of regions in the heap.
1043 uint num_regions() const { return _hrm->length(); }
1044
1045 // The max number of regions in the heap.
1046 uint max_regions() const { return _hrm->max_length(); }
1047
1048 // Max number of regions that can be comitted.
1049 uint max_expandable_regions() const { return _hrm->max_expandable_length(); }
1050
1051 // The number of regions that are completely free.
1052 uint num_free_regions() const { return _hrm->num_free_regions(); }
1053
1054 // The number of regions that can be allocated into.
1055 uint num_free_or_available_regions() const { return num_free_regions() + _hrm->available(); }
1056
1057 MemoryUsage get_auxiliary_data_memory_usage() const {
1058 return _hrm->get_auxiliary_data_memory_usage();
1059 }
1060
1061 // The number of regions that are not completely free.
1062 uint num_used_regions() const { return num_regions() - num_free_regions(); }
1063
1064 #ifdef ASSERT
1065 bool is_on_master_free_list(HeapRegion* hr) {
1066 return _hrm->is_free(hr);
1067 }
1068 #endif // ASSERT
1069
1070 inline void old_set_add(HeapRegion* hr);
1071 inline void old_set_remove(HeapRegion* hr);
1072
1073 inline void archive_set_add(HeapRegion* hr);
1074
1075 size_t non_young_capacity_bytes() {
1076 return (old_regions_count() + _archive_set.length() + humongous_regions_count()) * HeapRegion::GrainBytes;
1077 }
1078
1079 // Determine whether the given region is one that we are using as an
1080 // old GC alloc region.
1081 bool is_old_gc_alloc_region(HeapRegion* hr);
1082
1083 // Perform a collection of the heap; intended for use in implementing
1084 // "System.gc". This probably implies as full a collection as the
1085 // "CollectedHeap" supports.
1086 virtual void collect(GCCause::Cause cause);
1087
1088 // Perform a collection of the heap with the given cause; if the VM operation
1089 // fails to execute for any reason, retry only if retry_on_gc_failure is set.
1090 // Returns whether this collection actually executed.
1091 bool try_collect(GCCause::Cause cause, bool retry_on_gc_failure);
1092
1093 // True iff an evacuation has failed in the most-recent collection.
1094 bool evacuation_failed() { return _evacuation_failed; }
1095
1096 void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed);
1097 void prepend_to_freelist(FreeRegionList* list);
1098 void decrement_summary_bytes(size_t bytes);
1099
1100 virtual bool is_in(const void* p) const;
1101 #ifdef ASSERT
1102 // Returns whether p is in one of the available areas of the heap. Slow but
1103 // extensive version.
1104 bool is_in_exact(const void* p) const;
1105 #endif
1106
1107 // Return "TRUE" iff the given object address is within the collection
1108 // set. Assumes that the reference points into the heap.
1109 inline bool is_in_cset(const HeapRegion *hr);
1110 inline bool is_in_cset(oop obj);
1111 inline bool is_in_cset(HeapWord* addr);
1112
1113 inline bool is_in_cset_or_humongous(const oop obj);
1114
1115 private:
1116 // This array is used for a quick test on whether a reference points into
1117 // the collection set or not. Each of the array's elements denotes whether the
1118 // corresponding region is in the collection set or not.
1119 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test;
1120
1121 public:
1122
1123 inline InCSetState in_cset_state(const oop obj);
1124
1125 // Return "TRUE" iff the given object address is in the reserved
1126 // region of g1.
1127 bool is_in_g1_reserved(const void* p) const {
1128 return _hrm->reserved().contains(p);
1129 }
1130
1131 // Returns a MemRegion that corresponds to the space that has been
1132 // reserved for the heap
1133 MemRegion g1_reserved() const {
1134 return _hrm->reserved();
1135 }
1136
1137 G1HotCardCache* g1_hot_card_cache() const { return _hot_card_cache; }
1138
1139 G1CardTable* card_table() const {
1140 return _card_table;
1141 }
1142
1143 // Iteration functions.
1144
1145 // Iterate over all objects, calling "cl.do_object" on each.
1146 virtual void object_iterate(ObjectClosure* cl);
1147
1148 virtual void safe_object_iterate(ObjectClosure* cl) {
1149 object_iterate(cl);
1150 }
1151
1152 // Iterate over heap regions, in address order, terminating the
1153 // iteration early if the "do_heap_region" method returns "true".
1154 void heap_region_iterate(HeapRegionClosure* blk) const;
1155
1156 // Return the region with the given index. It assumes the index is valid.
1157 inline HeapRegion* region_at(uint index) const;
1158 inline HeapRegion* region_at_or_null(uint index) const;
1159
1160 // Return the next region (by index) that is part of the same
1161 // humongous object that hr is part of.
1162 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const;
1163
1164 // Calculate the region index of the given address. Given address must be
1165 // within the heap.
1166 inline uint addr_to_region(HeapWord* addr) const;
1167
1168 inline HeapWord* bottom_addr_for_region(uint index) const;
1169
1170 // Two functions to iterate over the heap regions in parallel. Threads
1171 // compete using the HeapRegionClaimer to claim the regions before
1172 // applying the closure on them.
1173 // The _from_worker_offset version uses the HeapRegionClaimer and
1174 // the worker id to calculate a start offset to prevent all workers to
1175 // start from the point.
1176 void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
1177 HeapRegionClaimer* hrclaimer,
1178 uint worker_id) const;
1179
1180 void heap_region_par_iterate_from_start(HeapRegionClosure* cl,
1181 HeapRegionClaimer* hrclaimer) const;
1182
1183 // Iterate over all regions currently in the current collection set.
1184 void collection_set_iterate_all(HeapRegionClosure* blk);
1185
1186 // Iterate over the regions in the current increment of the collection set.
1187 // Starts the iteration so that the start regions of a given worker id over the
1188 // set active_workers are evenly spread across the set of collection set regions
1189 // to be iterated.
1190 void collection_set_iterate_increment_from(HeapRegionClosure *blk, uint worker_id);
1191
1192 // Returns the HeapRegion that contains addr. addr must not be NULL.
1193 template <class T>
1194 inline HeapRegion* heap_region_containing(const T addr) const;
1195
1196 // Returns the HeapRegion that contains addr, or NULL if that is an uncommitted
1197 // region. addr must not be NULL.
1198 template <class T>
1199 inline HeapRegion* heap_region_containing_or_null(const T addr) const;
1200
1201 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1202 // each address in the (reserved) heap is a member of exactly
1203 // one block. The defining characteristic of a block is that it is
1204 // possible to find its size, and thus to progress forward to the next
1205 // block. (Blocks may be of different sizes.) Thus, blocks may
1206 // represent Java objects, or they might be free blocks in a
1207 // free-list-based heap (or subheap), as long as the two kinds are
1208 // distinguishable and the size of each is determinable.
1209
1210 // Returns the address of the start of the "block" that contains the
1211 // address "addr". We say "blocks" instead of "object" since some heaps
1212 // may not pack objects densely; a chunk may either be an object or a
1213 // non-object.
1214 virtual HeapWord* block_start(const void* addr) const;
1215
1216 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1217 // the block is an object.
1218 virtual bool block_is_obj(const HeapWord* addr) const;
1219
1220 // Section on thread-local allocation buffers (TLABs)
1221 // See CollectedHeap for semantics.
1222
1223 bool supports_tlab_allocation() const;
1224 size_t tlab_capacity(Thread* ignored) const;
1225 size_t tlab_used(Thread* ignored) const;
1226 size_t max_tlab_size() const;
1227 size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1228
1229 inline bool is_in_young(const oop obj);
1230
1231 // Returns "true" iff the given word_size is "very large".
1232 static bool is_humongous(size_t word_size) {
1233 // Note this has to be strictly greater-than as the TLABs
1234 // are capped at the humongous threshold and we want to
1235 // ensure that we don't try to allocate a TLAB as
1236 // humongous and that we don't allocate a humongous
1237 // object in a TLAB.
1238 return word_size > _humongous_object_threshold_in_words;
1239 }
1240
1241 // Returns the humongous threshold for a specific region size
1242 static size_t humongous_threshold_for(size_t region_size) {
1243 return (region_size / 2);
1244 }
1245
1246 // Returns the number of regions the humongous object of the given word size
1247 // requires.
1248 static size_t humongous_obj_size_in_regions(size_t word_size);
1249
1250 // Print the maximum heap capacity.
1251 virtual size_t max_capacity() const;
1252
1253 // Return the size of reserved memory. Returns different value than max_capacity() when AllocateOldGenAt is used.
1254 virtual size_t max_reserved_capacity() const;
1255
1256 virtual jlong millis_since_last_gc();
1257
1258
1259 // Convenience function to be used in situations where the heap type can be
1260 // asserted to be this type.
1261 static G1CollectedHeap* heap();
1262
1263 void set_region_short_lived_locked(HeapRegion* hr);
1264 // add appropriate methods for any other surv rate groups
1265
1266 const G1SurvivorRegions* survivor() const { return &_survivor; }
1267
1268 uint eden_regions_count() const { return _eden.length(); }
1269 uint survivor_regions_count() const { return _survivor.length(); }
1270 size_t eden_regions_used_bytes() const { return _eden.used_bytes(); }
1271 size_t survivor_regions_used_bytes() const { return _survivor.used_bytes(); }
1272 uint young_regions_count() const { return _eden.length() + _survivor.length(); }
1273 uint old_regions_count() const { return _old_set.length(); }
1274 uint archive_regions_count() const { return _archive_set.length(); }
1275 uint humongous_regions_count() const { return _humongous_set.length(); }
1276
1277 #ifdef ASSERT
1278 bool check_young_list_empty();
1279 #endif
1280
1281 // *** Stuff related to concurrent marking. It's not clear to me that so
1282 // many of these need to be public.
1283
1284 // The functions below are helper functions that a subclass of
1285 // "CollectedHeap" can use in the implementation of its virtual
1286 // functions.
1287 // This performs a concurrent marking of the live objects in a
1288 // bitmap off to the side.
1289 void do_concurrent_mark();
1290
1291 bool is_marked_next(oop obj) const;
1292
1293 // Determine if an object is dead, given the object and also
1294 // the region to which the object belongs. An object is dead
1295 // iff a) it was not allocated since the last mark, b) it
1296 // is not marked, and c) it is not in an archive region.
1297 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1298 return
1299 hr->is_obj_dead(obj, _cm->prev_mark_bitmap()) &&
1300 !hr->is_archive();
1301 }
1302
1303 // This function returns true when an object has been
1304 // around since the previous marking and hasn't yet
1305 // been marked during this marking, and is not in an archive region.
1306 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1307 return
1308 !hr->obj_allocated_since_next_marking(obj) &&
1309 !is_marked_next(obj) &&
1310 !hr->is_archive();
1311 }
1312
1313 // Determine if an object is dead, given only the object itself.
1314 // This will find the region to which the object belongs and
1315 // then call the region version of the same function.
1316
1317 // Added if it is NULL it isn't dead.
1318
1319 inline bool is_obj_dead(const oop obj) const;
1320
1321 inline bool is_obj_ill(const oop obj) const;
1322
1323 inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const;
1324 inline bool is_obj_dead_full(const oop obj) const;
1325
1326 G1ConcurrentMark* concurrent_mark() const { return _cm; }
1327
1328 // Refinement
1329
1330 G1ConcurrentRefine* concurrent_refine() const { return _cr; }
1331
1332 // Optimized nmethod scanning support routines
1333
1334 // Register the given nmethod with the G1 heap.
1335 virtual void register_nmethod(nmethod* nm);
1336
1337 // Unregister the given nmethod from the G1 heap.
1338 virtual void unregister_nmethod(nmethod* nm);
1339
1340 // No nmethod flushing needed.
1341 virtual void flush_nmethod(nmethod* nm) {}
1342
1343 // No nmethod verification implemented.
1344 virtual void verify_nmethod(nmethod* nm) {}
1345
1346 // Free up superfluous code root memory.
1347 void purge_code_root_memory();
1348
1349 // Rebuild the strong code root lists for each region
1350 // after a full GC.
1351 void rebuild_strong_code_roots();
1352
1353 // Partial cleaning of VM internal data structures.
1354 void string_dedup_cleaning(BoolObjectClosure* is_alive,
1355 OopClosure* keep_alive,
1356 G1GCPhaseTimes* phase_times = NULL);
1357
1358 // Performs cleaning of data structures after class unloading.
1359 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred);
1360
1361 // Redirty logged cards in the refinement queue.
1362 void redirty_logged_cards();
1363 // Verification
1364
1365 // Deduplicate the string
1366 virtual void deduplicate_string(oop str);
1367
1368 // Perform any cleanup actions necessary before allowing a verification.
1369 virtual void prepare_for_verify();
1370
1371 // Perform verification.
1372
1373 // vo == UsePrevMarking -> use "prev" marking information,
1374 // vo == UseNextMarking -> use "next" marking information
1375 // vo == UseFullMarking -> use "next" marking bitmap but no TAMS
1376 //
1377 // NOTE: Only the "prev" marking information is guaranteed to be
1378 // consistent most of the time, so most calls to this should use
1379 // vo == UsePrevMarking.
1380 // Currently, there is only one case where this is called with
1381 // vo == UseNextMarking, which is to verify the "next" marking
1382 // information at the end of remark.
1383 // Currently there is only one place where this is called with
1384 // vo == UseFullMarking, which is to verify the marking during a
1385 // full GC.
1386 void verify(VerifyOption vo);
1387
1388 // WhiteBox testing support.
1389 virtual bool supports_concurrent_phase_control() const;
1390 virtual bool request_concurrent_phase(const char* phase);
1391 bool is_heterogeneous_heap() const;
1392
1393 virtual WorkGang* get_safepoint_workers() { return _workers; }
1394
1395 // The methods below are here for convenience and dispatch the
1396 // appropriate method depending on value of the given VerifyOption
1397 // parameter. The values for that parameter, and their meanings,
1398 // are the same as those above.
1399
1400 bool is_obj_dead_cond(const oop obj,
1401 const HeapRegion* hr,
1402 const VerifyOption vo) const;
1403
1404 bool is_obj_dead_cond(const oop obj,
1405 const VerifyOption vo) const;
1406
1407 G1HeapSummary create_g1_heap_summary();
1408 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats);
1409
1410 // Printing
1411 private:
1412 void print_heap_regions() const;
1413 void print_regions_on(outputStream* st) const;
1414
1415 public:
1416 virtual void print_on(outputStream* st) const;
1417 virtual void print_extended_on(outputStream* st) const;
1418 virtual void print_on_error(outputStream* st) const;
1419
1420 virtual void print_gc_threads_on(outputStream* st) const;
1421 virtual void gc_threads_do(ThreadClosure* tc) const;
1422
1423 // Override
1424 void print_tracing_info() const;
1425
1426 // The following two methods are helpful for debugging RSet issues.
1427 void print_cset_rsets() PRODUCT_RETURN;
1428 void print_all_rsets() PRODUCT_RETURN;
1429
1430 size_t pending_card_num();
1431 };
1432
1433 class G1ParEvacuateFollowersClosure : public VoidClosure {
1434 private:
1435 double _start_term;
1436 double _term_time;
1437 size_t _term_attempts;
1438
1439 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
1440 void end_term_time() { _term_time += (os::elapsedTime() - _start_term); }
1441 protected:
1442 G1CollectedHeap* _g1h;
1443 G1ParScanThreadState* _par_scan_state;
1444 RefToScanQueueSet* _queues;
1445 ParallelTaskTerminator* _terminator;
1446 G1GCPhaseTimes::GCParPhases _phase;
1447
1448 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
1449 RefToScanQueueSet* queues() { return _queues; }
1450 ParallelTaskTerminator* terminator() { return _terminator; }
1451
1452 public:
1453 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
1454 G1ParScanThreadState* par_scan_state,
1455 RefToScanQueueSet* queues,
1456 ParallelTaskTerminator* terminator,
1457 G1GCPhaseTimes::GCParPhases phase)
1458 : _start_term(0.0), _term_time(0.0), _term_attempts(0),
1459 _g1h(g1h), _par_scan_state(par_scan_state),
1460 _queues(queues), _terminator(terminator), _phase(phase) {}
1461
1462 void do_void();
1463
1464 double term_time() const { return _term_time; }
1465 size_t term_attempts() const { return _term_attempts; }
1466
1467 private:
1468 inline bool offer_termination();
1469 };
1470
1471 #endif // SHARE_GC_G1_G1COLLECTEDHEAP_HPP