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/g1EdenRegions.hpp"
35 #include "gc/g1/g1EvacFailure.hpp"
36 #include "gc/g1/g1EvacStats.hpp"
37 #include "gc/g1/g1EvacuationInfo.hpp"
38 #include "gc/g1/g1GCPhaseTimes.hpp"
39 #include "gc/g1/g1HeapTransition.hpp"
40 #include "gc/g1/g1HeapVerifier.hpp"
41 #include "gc/g1/g1HRPrinter.hpp"
42 #include "gc/g1/g1HeapRegionAttr.hpp"
43 #include "gc/g1/g1MonitoringSupport.hpp"
44 #include "gc/g1/g1NUMA.hpp"
45 #include "gc/g1/g1RedirtyCardsQueue.hpp"
46 #include "gc/g1/g1SurvivorRegions.hpp"
47 #include "gc/g1/g1YCTypes.hpp"
48 #include "gc/g1/heapRegionManager.hpp"
49 #include "gc/g1/heapRegionSet.hpp"
50 #include "gc/g1/heterogeneousHeapRegionManager.hpp"
51 #include "gc/shared/barrierSet.hpp"
52 #include "gc/shared/collectedHeap.hpp"
53 #include "gc/shared/gcHeapSummary.hpp"
54 #include "gc/shared/plab.hpp"
55 #include "gc/shared/preservedMarks.hpp"
56 #include "gc/shared/softRefPolicy.hpp"
57 #include "memory/memRegion.hpp"
58 #include "utilities/stack.hpp"
59
60 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
61 // It uses the "Garbage First" heap organization and algorithm, which
62 // may combine concurrent marking with parallel, incremental compaction of
63 // heap subsets that will yield large amounts of garbage.
64
65 // Forward declarations
66 class HeapRegion;
67 class GenerationSpec;
68 class G1ParScanThreadState;
69 class G1ParScanThreadStateSet;
70 class G1ParScanThreadState;
71 class MemoryPool;
72 class MemoryManager;
73 class ObjectClosure;
74 class SpaceClosure;
75 class CompactibleSpaceClosure;
76 class Space;
77 class G1CardTableEntryClosure;
78 class G1CollectionSet;
79 class G1Policy;
80 class G1HotCardCache;
81 class G1RemSet;
82 class G1YoungRemSetSamplingThread;
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 G1CheckRegionAttrTableClosure;
154
155 private:
156 G1YoungRemSetSamplingThread* _young_gen_sampling_thread;
157
158 WorkGang* _workers;
159 G1CardTable* _card_table;
160
161 SoftRefPolicy _soft_ref_policy;
162
163 static size_t _humongous_object_threshold_in_words;
164
165 // These sets keep track of old, archive and humongous regions respectively.
166 HeapRegionSet _old_set;
167 HeapRegionSet _archive_set;
168 HeapRegionSet _humongous_set;
169
170 void eagerly_reclaim_humongous_regions();
171 // Start a new incremental collection set for the next pause.
172 void start_new_collection_set();
173
174 // The block offset table for the G1 heap.
175 G1BlockOffsetTable* _bot;
176
177 // Tears down the region sets / lists so that they are empty and the
178 // regions on the heap do not belong to a region set / list. The
179 // only exception is the humongous set which we leave unaltered. If
180 // free_list_only is true, it will only tear down the master free
181 // list. It is called before a Full GC (free_list_only == false) or
182 // before heap shrinking (free_list_only == true).
183 void tear_down_region_sets(bool free_list_only);
184
185 // Rebuilds the region sets / lists so that they are repopulated to
186 // reflect the contents of the heap. The only exception is the
187 // humongous set which was not torn down in the first place. If
188 // free_list_only is true, it will only rebuild the master free
189 // list. It is called after a Full GC (free_list_only == false) or
190 // after heap shrinking (free_list_only == true).
191 void rebuild_region_sets(bool free_list_only);
192
193 // Callback for region mapping changed events.
194 G1RegionMappingChangedListener _listener;
195
196 // Handle G1 NUMA support.
197 G1NUMA* _numa;
198
199 // The sequence of all heap regions in the heap.
200 HeapRegionManager* _hrm;
201
202 // Manages all allocations with regions except humongous object allocations.
203 G1Allocator* _allocator;
204
205 // Manages all heap verification.
206 G1HeapVerifier* _verifier;
207
208 // Outside of GC pauses, the number of bytes used in all regions other
209 // than the current allocation region(s).
210 volatile size_t _summary_bytes_used;
211
212 void increase_used(size_t bytes);
213 void decrease_used(size_t bytes);
214
215 void set_used(size_t bytes);
216
217 // Class that handles archive allocation ranges.
218 G1ArchiveAllocator* _archive_allocator;
219
220 // GC allocation statistics policy for survivors.
221 G1EvacStats _survivor_evac_stats;
222
223 // GC allocation statistics policy for tenured objects.
224 G1EvacStats _old_evac_stats;
225
226 // It specifies whether we should attempt to expand the heap after a
227 // region allocation failure. If heap expansion fails we set this to
228 // false so that we don't re-attempt the heap expansion (it's likely
229 // that subsequent expansion attempts will also fail if one fails).
230 // Currently, it is only consulted during GC and it's reset at the
231 // start of each GC.
232 bool _expand_heap_after_alloc_failure;
233
234 // Helper for monitoring and management support.
235 G1MonitoringSupport* _g1mm;
236
237 // Records whether the region at the given index is (still) a
238 // candidate for eager reclaim. Only valid for humongous start
239 // regions; other regions have unspecified values. Humongous start
240 // regions are initialized at start of collection pause, with
241 // candidates removed from the set as they are found reachable from
242 // roots or the young generation.
243 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> {
244 protected:
245 bool default_value() const { return false; }
246 public:
247 void clear() { G1BiasedMappedArray<bool>::clear(); }
248 void set_candidate(uint region, bool value) {
249 set_by_index(region, value);
250 }
251 bool is_candidate(uint region) {
252 return get_by_index(region);
253 }
254 };
255
256 HumongousReclaimCandidates _humongous_reclaim_candidates;
257 // Stores whether during humongous object registration we found candidate regions.
258 // If not, we can skip a few steps.
259 bool _has_humongous_reclaim_candidates;
260
261 G1HRPrinter _hr_printer;
262
263 // It decides whether an explicit GC should start a concurrent cycle
264 // instead of doing a STW GC. Currently, a concurrent cycle is
265 // explicitly started if:
266 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
267 // (b) cause == _g1_humongous_allocation
268 // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
269 // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent.
270 // (e) cause == _wb_conc_mark
271 bool should_do_concurrent_full_gc(GCCause::Cause cause);
272
273 // Return true if should upgrade to full gc after an incremental one.
274 bool should_upgrade_to_full_gc(GCCause::Cause cause);
275
276 // indicates whether we are in young or mixed GC mode
277 G1CollectorState _collector_state;
278
279 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
280 // concurrent cycles) we have started.
281 volatile uint _old_marking_cycles_started;
282
283 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
284 // concurrent cycles) we have completed.
285 volatile uint _old_marking_cycles_completed;
286
287 // This is a non-product method that is helpful for testing. It is
288 // called at the end of a GC and artificially expands the heap by
289 // allocating a number of dead regions. This way we can induce very
290 // frequent marking cycles and stress the cleanup / concurrent
291 // cleanup code more (as all the regions that will be allocated by
292 // this method will be found dead by the marking cycle).
293 void allocate_dummy_regions() PRODUCT_RETURN;
294
295 // If the HR printer is active, dump the state of the regions in the
296 // heap after a compaction.
297 void print_hrm_post_compaction();
298
299 // Create a memory mapper for auxiliary data structures of the given size and
300 // translation factor.
301 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description,
302 size_t size,
303 size_t translation_factor);
304
305 void trace_heap(GCWhen::Type when, const GCTracer* tracer);
306
307 // These are macros so that, if the assert fires, we get the correct
308 // line number, file, etc.
309
310 #define heap_locking_asserts_params(_extra_message_) \
311 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
312 (_extra_message_), \
313 BOOL_TO_STR(Heap_lock->owned_by_self()), \
314 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
315 BOOL_TO_STR(Thread::current()->is_VM_thread())
316
317 #define assert_heap_locked() \
318 do { \
319 assert(Heap_lock->owned_by_self(), \
320 heap_locking_asserts_params("should be holding the Heap_lock")); \
321 } while (0)
322
323 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
324 do { \
325 assert(Heap_lock->owned_by_self() || \
326 (SafepointSynchronize::is_at_safepoint() && \
327 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
328 heap_locking_asserts_params("should be holding the Heap_lock or " \
329 "should be at a safepoint")); \
330 } while (0)
331
332 #define assert_heap_locked_and_not_at_safepoint() \
333 do { \
334 assert(Heap_lock->owned_by_self() && \
335 !SafepointSynchronize::is_at_safepoint(), \
336 heap_locking_asserts_params("should be holding the Heap_lock and " \
337 "should not be at a safepoint")); \
338 } while (0)
339
340 #define assert_heap_not_locked() \
341 do { \
342 assert(!Heap_lock->owned_by_self(), \
343 heap_locking_asserts_params("should not be holding the Heap_lock")); \
344 } while (0)
345
346 #define assert_heap_not_locked_and_not_at_safepoint() \
347 do { \
348 assert(!Heap_lock->owned_by_self() && \
349 !SafepointSynchronize::is_at_safepoint(), \
350 heap_locking_asserts_params("should not be holding the Heap_lock and " \
351 "should not be at a safepoint")); \
352 } while (0)
353
354 #define assert_at_safepoint_on_vm_thread() \
355 do { \
356 assert_at_safepoint(); \
357 assert(Thread::current_or_null() != NULL, "no current thread"); \
358 assert(Thread::current()->is_VM_thread(), "current thread is not VM thread"); \
359 } while (0)
360
361 #ifdef ASSERT
362 #define assert_used_and_recalculate_used_equal(g1h) \
363 do { \
364 size_t cur_used_bytes = g1h->used(); \
365 size_t recal_used_bytes = g1h->recalculate_used(); \
366 assert(cur_used_bytes == recal_used_bytes, "Used(" SIZE_FORMAT ") is not" \
367 " same as recalculated used(" SIZE_FORMAT ").", \
368 cur_used_bytes, recal_used_bytes); \
369 } while (0)
370 #else
371 #define assert_used_and_recalculate_used_equal(g1h) do {} while(0)
372 #endif
373
374 const char* young_gc_name() const;
375
376 // The young region list.
377 G1EdenRegions _eden;
378 G1SurvivorRegions _survivor;
379
380 STWGCTimer* _gc_timer_stw;
381
382 G1NewTracer* _gc_tracer_stw;
383
384 // The current policy object for the collector.
385 G1Policy* _policy;
386 G1HeapSizingPolicy* _heap_sizing_policy;
387
388 G1CollectionSet _collection_set;
389
390 // Try to allocate a single non-humongous HeapRegion sufficient for
391 // an allocation of the given word_size. If do_expand is true,
392 // attempt to expand the heap if necessary to satisfy the allocation
393 // request. 'type' takes the type of region to be allocated. (Use constants
394 // Old, Eden, Humongous, Survivor defined in HeapRegionType.)
395 HeapRegion* new_region(size_t word_size,
396 HeapRegionType type,
397 bool do_expand,
398 uint node_index = G1NUMA::AnyNodeIndex);
399
400 // Initialize a contiguous set of free regions of length num_regions
401 // and starting at index first so that they appear as a single
402 // humongous region.
403 HeapWord* humongous_obj_allocate_initialize_regions(uint first,
404 uint num_regions,
405 size_t word_size);
406
407 // Attempt to allocate a humongous object of the given size. Return
408 // NULL if unsuccessful.
409 HeapWord* humongous_obj_allocate(size_t word_size);
410
411 // The following two methods, allocate_new_tlab() and
412 // mem_allocate(), are the two main entry points from the runtime
413 // into the G1's allocation routines. They have the following
414 // assumptions:
415 //
416 // * They should both be called outside safepoints.
417 //
418 // * They should both be called without holding the Heap_lock.
419 //
420 // * All allocation requests for new TLABs should go to
421 // allocate_new_tlab().
422 //
423 // * All non-TLAB allocation requests should go to mem_allocate().
424 //
425 // * If either call cannot satisfy the allocation request using the
426 // current allocating region, they will try to get a new one. If
427 // this fails, they will attempt to do an evacuation pause and
428 // retry the allocation.
429 //
430 // * If all allocation attempts fail, even after trying to schedule
431 // an evacuation pause, allocate_new_tlab() will return NULL,
432 // whereas mem_allocate() will attempt a heap expansion and/or
433 // schedule a Full GC.
434 //
435 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
436 // should never be called with word_size being humongous. All
437 // humongous allocation requests should go to mem_allocate() which
438 // will satisfy them with a special path.
439
440 virtual HeapWord* allocate_new_tlab(size_t min_size,
441 size_t requested_size,
442 size_t* actual_size);
443
444 virtual HeapWord* mem_allocate(size_t word_size,
445 bool* gc_overhead_limit_was_exceeded);
446
447 // First-level mutator allocation attempt: try to allocate out of
448 // the mutator alloc region without taking the Heap_lock. This
449 // should only be used for non-humongous allocations.
450 inline HeapWord* attempt_allocation(size_t min_word_size,
451 size_t desired_word_size,
452 size_t* actual_word_size);
453
454 // Second-level mutator allocation attempt: take the Heap_lock and
455 // retry the allocation attempt, potentially scheduling a GC
456 // pause. This should only be used for non-humongous allocations.
457 HeapWord* attempt_allocation_slow(size_t word_size);
458
459 // Takes the Heap_lock and attempts a humongous allocation. It can
460 // potentially schedule a GC pause.
461 HeapWord* attempt_allocation_humongous(size_t word_size);
462
463 // Allocation attempt that should be called during safepoints (e.g.,
464 // at the end of a successful GC). expect_null_mutator_alloc_region
465 // specifies whether the mutator alloc region is expected to be NULL
466 // or not.
467 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
468 bool expect_null_mutator_alloc_region);
469
470 // These methods are the "callbacks" from the G1AllocRegion class.
471
472 // For mutator alloc regions.
473 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force, uint node_index);
474 void retire_mutator_alloc_region(HeapRegion* alloc_region,
475 size_t allocated_bytes);
476
477 // For GC alloc regions.
478 bool has_more_regions(G1HeapRegionAttr dest);
479 HeapRegion* new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index);
480 void retire_gc_alloc_region(HeapRegion* alloc_region,
481 size_t allocated_bytes, G1HeapRegionAttr dest);
482
483 // - if explicit_gc is true, the GC is for a System.gc() etc,
484 // otherwise it's for a failed allocation.
485 // - if clear_all_soft_refs is true, all soft references should be
486 // cleared during the GC.
487 // - it returns false if it is unable to do the collection due to the
488 // GC locker being active, true otherwise.
489 bool do_full_collection(bool explicit_gc,
490 bool clear_all_soft_refs);
491
492 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread.
493 virtual void do_full_collection(bool clear_all_soft_refs);
494
495 // Callback from VM_G1CollectForAllocation operation.
496 // This function does everything necessary/possible to satisfy a
497 // failed allocation request (including collection, expansion, etc.)
498 HeapWord* satisfy_failed_allocation(size_t word_size,
499 bool* succeeded);
500 // Internal helpers used during full GC to split it up to
501 // increase readability.
502 void abort_concurrent_cycle();
503 void verify_before_full_collection(bool explicit_gc);
504 void prepare_heap_for_full_collection();
505 void prepare_heap_for_mutators();
506 void abort_refinement();
507 void verify_after_full_collection();
508 void print_heap_after_full_collection(G1HeapTransition* heap_transition);
509
510 // Helper method for satisfy_failed_allocation()
511 HeapWord* satisfy_failed_allocation_helper(size_t word_size,
512 bool do_gc,
513 bool clear_all_soft_refs,
514 bool expect_null_mutator_alloc_region,
515 bool* gc_succeeded);
516
517 // Attempting to expand the heap sufficiently
518 // to support an allocation of the given "word_size". If
519 // successful, perform the allocation and return the address of the
520 // allocated block, or else "NULL".
521 HeapWord* expand_and_allocate(size_t word_size);
522
523 // Process any reference objects discovered.
524 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states);
525
526 // If during an initial mark pause we may install a pending list head which is not
527 // otherwise reachable ensure that it is marked in the bitmap for concurrent marking
528 // to discover.
529 void make_pending_list_reachable();
530
531 // Merges the information gathered on a per-thread basis for all worker threads
532 // during GC into global variables.
533 void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states);
534 public:
535 G1YoungRemSetSamplingThread* sampling_thread() const { return _young_gen_sampling_thread; }
536
537 WorkGang* workers() const { return _workers; }
538
539 // Runs the given AbstractGangTask with the current active workers, returning the
540 // total time taken.
541 Tickspan run_task(AbstractGangTask* task);
542
543 G1Allocator* allocator() {
544 return _allocator;
545 }
546
547 G1HeapVerifier* verifier() {
548 return _verifier;
549 }
550
551 G1MonitoringSupport* g1mm() {
552 assert(_g1mm != NULL, "should have been initialized");
553 return _g1mm;
554 }
555
556 void resize_heap_if_necessary();
557
558 G1NUMA* numa() const { return _numa; }
559
560 // Expand the garbage-first heap by at least the given size (in bytes!).
561 // Returns true if the heap was expanded by the requested amount;
562 // false otherwise.
563 // (Rounds up to a HeapRegion boundary.)
564 bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL);
565 bool expand_single_region(uint node_index);
566
567 // Returns the PLAB statistics for a given destination.
568 inline G1EvacStats* alloc_buffer_stats(G1HeapRegionAttr dest);
569
570 // Determines PLAB size for a given destination.
571 inline size_t desired_plab_sz(G1HeapRegionAttr dest);
572
573 // Do anything common to GC's.
574 void gc_prologue(bool full);
575 void gc_epilogue(bool full);
576
577 // Does the given region fulfill remembered set based eager reclaim candidate requirements?
578 bool is_potential_eager_reclaim_candidate(HeapRegion* r) const;
579
580 // Modify the reclaim candidate set and test for presence.
581 // These are only valid for starts_humongous regions.
582 inline void set_humongous_reclaim_candidate(uint region, bool value);
583 inline bool is_humongous_reclaim_candidate(uint region);
584
585 // Remove from the reclaim candidate set. Also remove from the
586 // collection set so that later encounters avoid the slow path.
587 inline void set_humongous_is_live(oop obj);
588
589 // Register the given region to be part of the collection set.
590 inline void register_humongous_region_with_region_attr(uint index);
591 // Update region attributes table with information about all regions.
592 void register_regions_with_region_attr();
593 // We register a region with the fast "in collection set" test. We
594 // simply set to true the array slot corresponding to this region.
595 void register_young_region_with_region_attr(HeapRegion* r) {
596 _region_attr.set_in_young(r->hrm_index());
597 }
598 inline void register_region_with_region_attr(HeapRegion* r);
599 inline void register_old_region_with_region_attr(HeapRegion* r);
600 inline void register_optional_region_with_region_attr(HeapRegion* r);
601
602 void clear_region_attr(const HeapRegion* hr) {
603 _region_attr.clear(hr);
604 }
605
606 void clear_region_attr() {
607 _region_attr.clear();
608 }
609
610 // Verify that the G1RegionAttr remset tracking corresponds to actual remset tracking
611 // for all regions.
612 void verify_region_attr_remset_update() PRODUCT_RETURN;
613
614 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause);
615
616 // This is called at the start of either a concurrent cycle or a Full
617 // GC to update the number of old marking cycles started.
618 void increment_old_marking_cycles_started();
619
620 // This is called at the end of either a concurrent cycle or a Full
621 // GC to update the number of old marking cycles completed. Those two
622 // can happen in a nested fashion, i.e., we start a concurrent
623 // cycle, a Full GC happens half-way through it which ends first,
624 // and then the cycle notices that a Full GC happened and ends
625 // too. The concurrent parameter is a boolean to help us do a bit
626 // tighter consistency checking in the method. If concurrent is
627 // false, the caller is the inner caller in the nesting (i.e., the
628 // Full GC). If concurrent is true, the caller is the outer caller
629 // in this nesting (i.e., the concurrent cycle). Further nesting is
630 // not currently supported. The end of this call also notifies
631 // the FullGCCount_lock in case a Java thread is waiting for a full
632 // GC to happen (e.g., it called System.gc() with
633 // +ExplicitGCInvokesConcurrent).
634 void increment_old_marking_cycles_completed(bool concurrent);
635
636 uint old_marking_cycles_completed() {
637 return _old_marking_cycles_completed;
638 }
639
640 G1HRPrinter* hr_printer() { return &_hr_printer; }
641
642 // Allocates a new heap region instance.
643 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr);
644
645 // Allocate the highest free region in the reserved heap. This will commit
646 // regions as necessary.
647 HeapRegion* alloc_highest_free_region();
648
649 // Frees a non-humongous region by initializing its contents and
650 // adding it to the free list that's passed as a parameter (this is
651 // usually a local list which will be appended to the master free
652 // list later). The used bytes of freed regions are accumulated in
653 // pre_used. If skip_remset is true, the region's RSet will not be freed
654 // up. If skip_hot_card_cache is true, the region's hot card cache will not
655 // be freed up. The assumption is that this will be done later.
656 // The locked parameter indicates if the caller has already taken
657 // care of proper synchronization. This may allow some optimizations.
658 void free_region(HeapRegion* hr,
659 FreeRegionList* free_list,
660 bool skip_remset,
661 bool skip_hot_card_cache = false,
662 bool locked = false);
663
664 // It dirties the cards that cover the block so that the post
665 // write barrier never queues anything when updating objects on this
666 // block. It is assumed (and in fact we assert) that the block
667 // belongs to a young region.
668 inline void dirty_young_block(HeapWord* start, size_t word_size);
669
670 // Frees a humongous region by collapsing it into individual regions
671 // and calling free_region() for each of them. The freed regions
672 // will be added to the free list that's passed as a parameter (this
673 // is usually a local list which will be appended to the master free
674 // list later).
675 // The method assumes that only a single thread is ever calling
676 // this for a particular region at once.
677 void free_humongous_region(HeapRegion* hr,
678 FreeRegionList* free_list);
679
680 // Facility for allocating in 'archive' regions in high heap memory and
681 // recording the allocated ranges. These should all be called from the
682 // VM thread at safepoints, without the heap lock held. They can be used
683 // to create and archive a set of heap regions which can be mapped at the
684 // same fixed addresses in a subsequent JVM invocation.
685 void begin_archive_alloc_range(bool open = false);
686
687 // Check if the requested size would be too large for an archive allocation.
688 bool is_archive_alloc_too_large(size_t word_size);
689
690 // Allocate memory of the requested size from the archive region. This will
691 // return NULL if the size is too large or if no memory is available. It
692 // does not trigger a garbage collection.
693 HeapWord* archive_mem_allocate(size_t word_size);
694
695 // Optionally aligns the end address and returns the allocated ranges in
696 // an array of MemRegions in order of ascending addresses.
697 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
698 size_t end_alignment_in_bytes = 0);
699
700 // Facility for allocating a fixed range within the heap and marking
701 // the containing regions as 'archive'. For use at JVM init time, when the
702 // caller may mmap archived heap data at the specified range(s).
703 // Verify that the MemRegions specified in the argument array are within the
704 // reserved heap.
705 bool check_archive_addresses(MemRegion* range, size_t count);
706
707 // Commit the appropriate G1 regions containing the specified MemRegions
708 // and mark them as 'archive' regions. The regions in the array must be
709 // non-overlapping and in order of ascending address.
710 bool alloc_archive_regions(MemRegion* range, size_t count, bool open);
711
712 // Insert any required filler objects in the G1 regions around the specified
713 // ranges to make the regions parseable. This must be called after
714 // alloc_archive_regions, and after class loading has occurred.
715 void fill_archive_regions(MemRegion* range, size_t count);
716
717 // For each of the specified MemRegions, uncommit the containing G1 regions
718 // which had been allocated by alloc_archive_regions. This should be called
719 // rather than fill_archive_regions at JVM init time if the archive file
720 // mapping failed, with the same non-overlapping and sorted MemRegion array.
721 void dealloc_archive_regions(MemRegion* range, size_t count, bool is_open);
722
723 oop materialize_archived_object(oop obj);
724
725 private:
726
727 // Shrink the garbage-first heap by at most the given size (in bytes!).
728 // (Rounds down to a HeapRegion boundary.)
729 void shrink(size_t expand_bytes);
730 void shrink_helper(size_t expand_bytes);
731
732 #if TASKQUEUE_STATS
733 static void print_taskqueue_stats_hdr(outputStream* const st);
734 void print_taskqueue_stats() const;
735 void reset_taskqueue_stats();
736 #endif // TASKQUEUE_STATS
737
738 // Schedule the VM operation that will do an evacuation pause to
739 // satisfy an allocation request of word_size. *succeeded will
740 // return whether the VM operation was successful (it did do an
741 // evacuation pause) or not (another thread beat us to it or the GC
742 // locker was active). Given that we should not be holding the
743 // Heap_lock when we enter this method, we will pass the
744 // gc_count_before (i.e., total_collections()) as a parameter since
745 // it has to be read while holding the Heap_lock. Currently, both
746 // methods that call do_collection_pause() release the Heap_lock
747 // before the call, so it's easy to read gc_count_before just before.
748 HeapWord* do_collection_pause(size_t word_size,
749 uint gc_count_before,
750 bool* succeeded,
751 GCCause::Cause gc_cause);
752
753 void wait_for_root_region_scanning();
754
755 // The guts of the incremental collection pause, executed by the vm
756 // thread. It returns false if it is unable to do the collection due
757 // to the GC locker being active, true otherwise
758 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
759
760 G1HeapVerifier::G1VerifyType young_collection_verify_type() const;
761 void verify_before_young_collection(G1HeapVerifier::G1VerifyType type);
762 void verify_after_young_collection(G1HeapVerifier::G1VerifyType type);
763
764 void calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms);
765
766 // Actually do the work of evacuating the parts of the collection set.
767 void evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states);
768 void evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states);
769 private:
770 // Evacuate the next set of optional regions.
771 void evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states);
772
773 public:
774 void pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss);
775 void post_evacuate_collection_set(G1EvacuationInfo& evacuation_info,
776 G1RedirtyCardsQueueSet* rdcqs,
777 G1ParScanThreadStateSet* pss);
778
779 void expand_heap_after_young_collection();
780 // Update object copying statistics.
781 void record_obj_copy_mem_stats();
782
783 // The hot card cache for remembered set insertion optimization.
784 G1HotCardCache* _hot_card_cache;
785
786 // The g1 remembered set of the heap.
787 G1RemSet* _rem_set;
788
789 // After a collection pause, convert the regions in the collection set into free
790 // regions.
791 void free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words);
792
793 // Abandon the current collection set without recording policy
794 // statistics or updating free lists.
795 void abandon_collection_set(G1CollectionSet* collection_set);
796
797 // The concurrent marker (and the thread it runs in.)
798 G1ConcurrentMark* _cm;
799 G1ConcurrentMarkThread* _cm_thread;
800
801 // The concurrent refiner.
802 G1ConcurrentRefine* _cr;
803
804 // The parallel task queues
805 RefToScanQueueSet *_task_queues;
806
807 // True iff a evacuation has failed in the current collection.
808 bool _evacuation_failed;
809
810 EvacuationFailedInfo* _evacuation_failed_info_array;
811
812 // Failed evacuations cause some logical from-space objects to have
813 // forwarding pointers to themselves. Reset them.
814 void remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs);
815
816 // Restore the objects in the regions in the collection set after an
817 // evacuation failure.
818 void restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs);
819
820 PreservedMarksSet _preserved_marks_set;
821
822 // Preserve the mark of "obj", if necessary, in preparation for its mark
823 // word being overwritten with a self-forwarding-pointer.
824 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m);
825
826 #ifndef PRODUCT
827 // Support for forcing evacuation failures. Analogous to
828 // PromotionFailureALot for the other collectors.
829
830 // Records whether G1EvacuationFailureALot should be in effect
831 // for the current GC
832 bool _evacuation_failure_alot_for_current_gc;
833
834 // Used to record the GC number for interval checking when
835 // determining whether G1EvaucationFailureALot is in effect
836 // for the current GC.
837 size_t _evacuation_failure_alot_gc_number;
838
839 // Count of the number of evacuations between failures.
840 volatile size_t _evacuation_failure_alot_count;
841
842 // Set whether G1EvacuationFailureALot should be in effect
843 // for the current GC (based upon the type of GC and which
844 // command line flags are set);
845 inline bool evacuation_failure_alot_for_gc_type(bool for_young_gc,
846 bool during_initial_mark,
847 bool mark_or_rebuild_in_progress);
848
849 inline void set_evacuation_failure_alot_for_current_gc();
850
851 // Return true if it's time to cause an evacuation failure.
852 inline bool evacuation_should_fail();
853
854 // Reset the G1EvacuationFailureALot counters. Should be called at
855 // the end of an evacuation pause in which an evacuation failure occurred.
856 inline void reset_evacuation_should_fail();
857 #endif // !PRODUCT
858
859 // ("Weak") Reference processing support.
860 //
861 // G1 has 2 instances of the reference processor class. One
862 // (_ref_processor_cm) handles reference object discovery
863 // and subsequent processing during concurrent marking cycles.
864 //
865 // The other (_ref_processor_stw) handles reference object
866 // discovery and processing during full GCs and incremental
867 // evacuation pauses.
868 //
869 // During an incremental pause, reference discovery will be
870 // temporarily disabled for _ref_processor_cm and will be
871 // enabled for _ref_processor_stw. At the end of the evacuation
872 // pause references discovered by _ref_processor_stw will be
873 // processed and discovery will be disabled. The previous
874 // setting for reference object discovery for _ref_processor_cm
875 // will be re-instated.
876 //
877 // At the start of marking:
878 // * Discovery by the CM ref processor is verified to be inactive
879 // and it's discovered lists are empty.
880 // * Discovery by the CM ref processor is then enabled.
881 //
882 // At the end of marking:
883 // * Any references on the CM ref processor's discovered
884 // lists are processed (possibly MT).
885 //
886 // At the start of full GC we:
887 // * Disable discovery by the CM ref processor and
888 // empty CM ref processor's discovered lists
889 // (without processing any entries).
890 // * Verify that the STW ref processor is inactive and it's
891 // discovered lists are empty.
892 // * Temporarily set STW ref processor discovery as single threaded.
893 // * Temporarily clear the STW ref processor's _is_alive_non_header
894 // field.
895 // * Finally enable discovery by the STW ref processor.
896 //
897 // The STW ref processor is used to record any discovered
898 // references during the full GC.
899 //
900 // At the end of a full GC we:
901 // * Enqueue any reference objects discovered by the STW ref processor
902 // that have non-live referents. This has the side-effect of
903 // making the STW ref processor inactive by disabling discovery.
904 // * Verify that the CM ref processor is still inactive
905 // and no references have been placed on it's discovered
906 // lists (also checked as a precondition during initial marking).
907
908 // The (stw) reference processor...
909 ReferenceProcessor* _ref_processor_stw;
910
911 // During reference object discovery, the _is_alive_non_header
912 // closure (if non-null) is applied to the referent object to
913 // determine whether the referent is live. If so then the
914 // reference object does not need to be 'discovered' and can
915 // be treated as a regular oop. This has the benefit of reducing
916 // the number of 'discovered' reference objects that need to
917 // be processed.
918 //
919 // Instance of the is_alive closure for embedding into the
920 // STW reference processor as the _is_alive_non_header field.
921 // Supplying a value for the _is_alive_non_header field is
922 // optional but doing so prevents unnecessary additions to
923 // the discovered lists during reference discovery.
924 G1STWIsAliveClosure _is_alive_closure_stw;
925
926 G1STWSubjectToDiscoveryClosure _is_subject_to_discovery_stw;
927
928 // The (concurrent marking) reference processor...
929 ReferenceProcessor* _ref_processor_cm;
930
931 // Instance of the concurrent mark is_alive closure for embedding
932 // into the Concurrent Marking reference processor as the
933 // _is_alive_non_header field. Supplying a value for the
934 // _is_alive_non_header field is optional but doing so prevents
935 // unnecessary additions to the discovered lists during reference
936 // discovery.
937 G1CMIsAliveClosure _is_alive_closure_cm;
938
939 G1CMSubjectToDiscoveryClosure _is_subject_to_discovery_cm;
940 public:
941
942 RefToScanQueue *task_queue(uint i) const;
943
944 uint num_task_queues() const;
945
946 // Create a G1CollectedHeap.
947 // Must call the initialize method afterwards.
948 // May not return if something goes wrong.
949 G1CollectedHeap();
950
951 private:
952 jint initialize_concurrent_refinement();
953 jint initialize_young_gen_sampling_thread();
954 public:
955 // Initialize the G1CollectedHeap to have the initial and
956 // maximum sizes and remembered and barrier sets
957 // specified by the policy object.
958 jint initialize();
959
960 virtual void stop();
961 virtual void safepoint_synchronize_begin();
962 virtual void safepoint_synchronize_end();
963
964 // Does operations required after initialization has been done.
965 void post_initialize();
966
967 // Initialize weak reference processing.
968 void ref_processing_init();
969
970 virtual Name kind() const {
971 return CollectedHeap::G1;
972 }
973
974 virtual const char* name() const {
975 return "G1";
976 }
977
978 const G1CollectorState* collector_state() const { return &_collector_state; }
979 G1CollectorState* collector_state() { return &_collector_state; }
980
981 // The current policy object for the collector.
982 G1Policy* policy() const { return _policy; }
983 // The remembered set.
984 G1RemSet* rem_set() const { return _rem_set; }
985
986 inline G1GCPhaseTimes* phase_times() const;
987
988 HeapRegionManager* hrm() const { return _hrm; }
989
990 const G1CollectionSet* collection_set() const { return &_collection_set; }
991 G1CollectionSet* collection_set() { return &_collection_set; }
992
993 virtual SoftRefPolicy* soft_ref_policy();
994
995 virtual void initialize_serviceability();
996 virtual MemoryUsage memory_usage();
997 virtual GrowableArray<GCMemoryManager*> memory_managers();
998 virtual GrowableArray<MemoryPool*> memory_pools();
999
1000 // Try to minimize the remembered set.
1001 void scrub_rem_set();
1002
1003 // Apply the given closure on all cards in the Hot Card Cache, emptying it.
1004 void iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id);
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
1021 virtual size_t capacity() const;
1022 virtual size_t used() const;
1023 // This should be called when we're not holding the heap lock. The
1024 // result might be a bit inaccurate.
1025 size_t used_unlocked() const;
1026 size_t recalculate_used() const;
1027
1028 // These virtual functions do the actual allocation.
1029 // Some heaps may offer a contiguous region for shared non-blocking
1030 // allocation, via inlined code (by exporting the address of the top and
1031 // end fields defining the extent of the contiguous allocation region.)
1032 // But G1CollectedHeap doesn't yet support this.
1033
1034 virtual bool is_maximal_no_gc() const {
1035 return _hrm->available() == 0;
1036 }
1037
1038 // Returns whether there are any regions left in the heap for allocation.
1039 bool has_regions_left_for_allocation() const {
1040 return !is_maximal_no_gc() || num_free_regions() != 0;
1041 }
1042
1043 // The current number of regions in the heap.
1044 uint num_regions() const { return _hrm->length(); }
1045
1046 // The max number of regions in the heap.
1047 uint max_regions() const { return _hrm->max_length(); }
1048
1049 // Max number of regions that can be comitted.
1050 uint max_expandable_regions() const { return _hrm->max_expandable_length(); }
1051
1052 // The number of regions that are completely free.
1053 uint num_free_regions() const { return _hrm->num_free_regions(); }
1054
1055 // The number of regions that can be allocated into.
1056 uint num_free_or_available_regions() const { return num_free_regions() + _hrm->available(); }
1057
1058 MemoryUsage get_auxiliary_data_memory_usage() const {
1059 return _hrm->get_auxiliary_data_memory_usage();
1060 }
1061
1062 // The number of regions that are not completely free.
1063 uint num_used_regions() const { return num_regions() - num_free_regions(); }
1064
1065 #ifdef ASSERT
1066 bool is_on_master_free_list(HeapRegion* hr) {
1067 return _hrm->is_free(hr);
1068 }
1069 #endif // ASSERT
1070
1071 inline void old_set_add(HeapRegion* hr);
1072 inline void old_set_remove(HeapRegion* hr);
1073
1074 inline void archive_set_add(HeapRegion* hr);
1075
1076 size_t non_young_capacity_bytes() {
1077 return (old_regions_count() + _archive_set.length() + humongous_regions_count()) * HeapRegion::GrainBytes;
1078 }
1079
1080 // Determine whether the given region is one that we are using as an
1081 // old GC alloc region.
1082 bool is_old_gc_alloc_region(HeapRegion* hr);
1083
1084 // Perform a collection of the heap; intended for use in implementing
1085 // "System.gc". This probably implies as full a collection as the
1086 // "CollectedHeap" supports.
1087 virtual void collect(GCCause::Cause cause);
1088
1089 // Perform a collection of the heap with the given cause; if the VM operation
1090 // fails to execute for any reason, retry only if retry_on_gc_failure is set.
1091 // Returns whether this collection actually executed.
1092 bool try_collect(GCCause::Cause cause, bool retry_on_gc_failure);
1093
1094 // True iff an evacuation has failed in the most-recent collection.
1095 bool evacuation_failed() { return _evacuation_failed; }
1096
1097 void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed);
1098 void prepend_to_freelist(FreeRegionList* list);
1099 void decrement_summary_bytes(size_t bytes);
1100
1101 virtual bool is_in(const void* p) const;
1102 #ifdef ASSERT
1103 // Returns whether p is in one of the available areas of the heap. Slow but
1104 // extensive version.
1105 bool is_in_exact(const void* p) const;
1106 #endif
1107
1108 // Return "TRUE" iff the given object address is within the collection
1109 // set. Assumes that the reference points into the heap.
1110 inline bool is_in_cset(const HeapRegion *hr);
1111 inline bool is_in_cset(oop obj);
1112 inline bool is_in_cset(HeapWord* addr);
1113
1114 inline bool is_in_cset_or_humongous(const oop obj);
1115
1116 private:
1117 // This array is used for a quick test on whether a reference points into
1118 // the collection set or not. Each of the array's elements denotes whether the
1119 // corresponding region is in the collection set or not.
1120 G1HeapRegionAttrBiasedMappedArray _region_attr;
1121
1122 public:
1123
1124 inline G1HeapRegionAttr region_attr(const void* obj) const;
1125 inline G1HeapRegionAttr region_attr(uint idx) const;
1126
1127 // Return "TRUE" iff the given object address is in the reserved
1128 // region of g1.
1129 bool is_in_g1_reserved(const void* p) const {
1130 return _hrm->reserved().contains(p);
1131 }
1132
1133 // Returns a MemRegion that corresponds to the space that has been
1134 // reserved for the heap
1135 MemRegion g1_reserved() const {
1136 return _hrm->reserved();
1137 }
1138
1139 MemRegion reserved_region() const {
1140 return _reserved;
1141 }
1142
1143 HeapWord* base() const {
1144 return _reserved.start();
1145 }
1146
1147 bool is_in_reserved(const void* addr) const {
1148 return _reserved.contains(addr);
1149 }
1150
1151 G1HotCardCache* g1_hot_card_cache() const { return _hot_card_cache; }
1152
1153 G1CardTable* card_table() const {
1154 return _card_table;
1155 }
1156
1157 // Iteration functions.
1158
1159 // Iterate over all objects, calling "cl.do_object" on each.
1160 virtual void object_iterate(ObjectClosure* cl);
1161
1162 virtual void safe_object_iterate(ObjectClosure* cl) {
1163 object_iterate(cl);
1164 }
1165
1166 // Iterate over heap regions, in address order, terminating the
1167 // iteration early if the "do_heap_region" method returns "true".
1168 void heap_region_iterate(HeapRegionClosure* blk) const;
1169
1170 // Return the region with the given index. It assumes the index is valid.
1171 inline HeapRegion* region_at(uint index) const;
1172 inline HeapRegion* region_at_or_null(uint index) const;
1173
1174 // Return the next region (by index) that is part of the same
1175 // humongous object that hr is part of.
1176 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const;
1177
1178 // Calculate the region index of the given address. Given address must be
1179 // within the heap.
1180 inline uint addr_to_region(HeapWord* addr) const;
1181
1182 inline HeapWord* bottom_addr_for_region(uint index) const;
1183
1184 // Two functions to iterate over the heap regions in parallel. Threads
1185 // compete using the HeapRegionClaimer to claim the regions before
1186 // applying the closure on them.
1187 // The _from_worker_offset version uses the HeapRegionClaimer and
1188 // the worker id to calculate a start offset to prevent all workers to
1189 // start from the point.
1190 void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
1191 HeapRegionClaimer* hrclaimer,
1192 uint worker_id) const;
1193
1194 void heap_region_par_iterate_from_start(HeapRegionClosure* cl,
1195 HeapRegionClaimer* hrclaimer) const;
1196
1197 // Iterate over all regions currently in the current collection set.
1198 void collection_set_iterate_all(HeapRegionClosure* blk);
1199
1200 // Iterate over the regions in the current increment of the collection set.
1201 // Starts the iteration so that the start regions of a given worker id over the
1202 // set active_workers are evenly spread across the set of collection set regions
1203 // to be iterated.
1204 // The variant with the HeapRegionClaimer guarantees that the closure will be
1205 // applied to a particular region exactly once.
1206 void collection_set_iterate_increment_from(HeapRegionClosure *blk, uint worker_id) {
1207 collection_set_iterate_increment_from(blk, NULL, worker_id);
1208 }
1209 void collection_set_iterate_increment_from(HeapRegionClosure *blk, HeapRegionClaimer* hr_claimer, uint worker_id);
1210
1211 // Returns the HeapRegion that contains addr. addr must not be NULL.
1212 template <class T>
1213 inline HeapRegion* heap_region_containing(const T addr) const;
1214
1215 // Returns the HeapRegion that contains addr, or NULL if that is an uncommitted
1216 // region. addr must not be NULL.
1217 template <class T>
1218 inline HeapRegion* heap_region_containing_or_null(const T addr) const;
1219
1220 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1221 // each address in the (reserved) heap is a member of exactly
1222 // one block. The defining characteristic of a block is that it is
1223 // possible to find its size, and thus to progress forward to the next
1224 // block. (Blocks may be of different sizes.) Thus, blocks may
1225 // represent Java objects, or they might be free blocks in a
1226 // free-list-based heap (or subheap), as long as the two kinds are
1227 // distinguishable and the size of each is determinable.
1228
1229 // Returns the address of the start of the "block" that contains the
1230 // address "addr". We say "blocks" instead of "object" since some heaps
1231 // may not pack objects densely; a chunk may either be an object or a
1232 // non-object.
1233 HeapWord* block_start(const void* addr) const;
1234
1235 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1236 // the block is an object.
1237 bool block_is_obj(const HeapWord* addr) const;
1238
1239 // Section on thread-local allocation buffers (TLABs)
1240 // See CollectedHeap for semantics.
1241
1242 bool supports_tlab_allocation() const;
1243 size_t tlab_capacity(Thread* ignored) const;
1244 size_t tlab_used(Thread* ignored) const;
1245 size_t max_tlab_size() const;
1246 size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1247
1248 inline bool is_in_young(const oop obj);
1249
1250 // Returns "true" iff the given word_size is "very large".
1251 static bool is_humongous(size_t word_size) {
1252 // Note this has to be strictly greater-than as the TLABs
1253 // are capped at the humongous threshold and we want to
1254 // ensure that we don't try to allocate a TLAB as
1255 // humongous and that we don't allocate a humongous
1256 // object in a TLAB.
1257 return word_size > _humongous_object_threshold_in_words;
1258 }
1259
1260 // Returns the humongous threshold for a specific region size
1261 static size_t humongous_threshold_for(size_t region_size) {
1262 return (region_size / 2);
1263 }
1264
1265 // Returns the number of regions the humongous object of the given word size
1266 // requires.
1267 static size_t humongous_obj_size_in_regions(size_t word_size);
1268
1269 // Print the maximum heap capacity.
1270 virtual size_t max_capacity() const;
1271
1272 // Return the size of reserved memory. Returns different value than max_capacity() when AllocateOldGenAt is used.
1273 virtual size_t max_reserved_capacity() const;
1274
1275 virtual jlong millis_since_last_gc();
1276
1277
1278 // Convenience function to be used in situations where the heap type can be
1279 // asserted to be this type.
1280 static G1CollectedHeap* heap();
1281
1282 void set_region_short_lived_locked(HeapRegion* hr);
1283 // add appropriate methods for any other surv rate groups
1284
1285 const G1SurvivorRegions* survivor() const { return &_survivor; }
1286
1287 uint eden_regions_count() const { return _eden.length(); }
1288 uint survivor_regions_count() const { return _survivor.length(); }
1289 size_t eden_regions_used_bytes() const { return _eden.used_bytes(); }
1290 size_t survivor_regions_used_bytes() const { return _survivor.used_bytes(); }
1291 uint young_regions_count() const { return _eden.length() + _survivor.length(); }
1292 uint old_regions_count() const { return _old_set.length(); }
1293 uint archive_regions_count() const { return _archive_set.length(); }
1294 uint humongous_regions_count() const { return _humongous_set.length(); }
1295
1296 #ifdef ASSERT
1297 bool check_young_list_empty();
1298 #endif
1299
1300 // *** Stuff related to concurrent marking. It's not clear to me that so
1301 // many of these need to be public.
1302
1303 // The functions below are helper functions that a subclass of
1304 // "CollectedHeap" can use in the implementation of its virtual
1305 // functions.
1306 // This performs a concurrent marking of the live objects in a
1307 // bitmap off to the side.
1308 void do_concurrent_mark();
1309
1310 bool is_marked_next(oop obj) const;
1311
1312 // Determine if an object is dead, given the object and also
1313 // the region to which the object belongs. An object is dead
1314 // iff a) it was not allocated since the last mark, b) it
1315 // is not marked, and c) it is not in an archive region.
1316 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1317 return
1318 hr->is_obj_dead(obj, _cm->prev_mark_bitmap()) &&
1319 !hr->is_archive();
1320 }
1321
1322 // This function returns true when an object has been
1323 // around since the previous marking and hasn't yet
1324 // been marked during this marking, and is not in an archive region.
1325 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1326 return
1327 !hr->obj_allocated_since_next_marking(obj) &&
1328 !is_marked_next(obj) &&
1329 !hr->is_archive();
1330 }
1331
1332 // Determine if an object is dead, given only the object itself.
1333 // This will find the region to which the object belongs and
1334 // then call the region version of the same function.
1335
1336 // Added if it is NULL it isn't dead.
1337
1338 inline bool is_obj_dead(const oop obj) const;
1339
1340 inline bool is_obj_ill(const oop obj) const;
1341
1342 inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const;
1343 inline bool is_obj_dead_full(const oop obj) const;
1344
1345 G1ConcurrentMark* concurrent_mark() const { return _cm; }
1346
1347 // Refinement
1348
1349 G1ConcurrentRefine* concurrent_refine() const { return _cr; }
1350
1351 // Optimized nmethod scanning support routines
1352
1353 // Register the given nmethod with the G1 heap.
1354 virtual void register_nmethod(nmethod* nm);
1355
1356 // Unregister the given nmethod from the G1 heap.
1357 virtual void unregister_nmethod(nmethod* nm);
1358
1359 // No nmethod flushing needed.
1360 virtual void flush_nmethod(nmethod* nm) {}
1361
1362 // No nmethod verification implemented.
1363 virtual void verify_nmethod(nmethod* nm) {}
1364
1365 // Free up superfluous code root memory.
1366 void purge_code_root_memory();
1367
1368 // Rebuild the strong code root lists for each region
1369 // after a full GC.
1370 void rebuild_strong_code_roots();
1371
1372 // Partial cleaning of VM internal data structures.
1373 void string_dedup_cleaning(BoolObjectClosure* is_alive,
1374 OopClosure* keep_alive,
1375 G1GCPhaseTimes* phase_times = NULL);
1376
1377 // Performs cleaning of data structures after class unloading.
1378 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred);
1379
1380 // Redirty logged cards in the refinement queue.
1381 void redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs);
1382
1383 // Verification
1384
1385 // Deduplicate the string
1386 virtual void deduplicate_string(oop str);
1387
1388 // Perform any cleanup actions necessary before allowing a verification.
1389 virtual void prepare_for_verify();
1390
1391 // Perform verification.
1392
1393 // vo == UsePrevMarking -> use "prev" marking information,
1394 // vo == UseNextMarking -> use "next" marking information
1395 // vo == UseFullMarking -> use "next" marking bitmap but no TAMS
1396 //
1397 // NOTE: Only the "prev" marking information is guaranteed to be
1398 // consistent most of the time, so most calls to this should use
1399 // vo == UsePrevMarking.
1400 // Currently, there is only one case where this is called with
1401 // vo == UseNextMarking, which is to verify the "next" marking
1402 // information at the end of remark.
1403 // Currently there is only one place where this is called with
1404 // vo == UseFullMarking, which is to verify the marking during a
1405 // full GC.
1406 void verify(VerifyOption vo);
1407
1408 // WhiteBox testing support.
1409 virtual bool supports_concurrent_phase_control() const;
1410 virtual bool request_concurrent_phase(const char* phase);
1411 bool is_heterogeneous_heap() const;
1412
1413 virtual WorkGang* get_safepoint_workers() { return _workers; }
1414
1415 // The methods below are here for convenience and dispatch the
1416 // appropriate method depending on value of the given VerifyOption
1417 // parameter. The values for that parameter, and their meanings,
1418 // are the same as those above.
1419
1420 bool is_obj_dead_cond(const oop obj,
1421 const HeapRegion* hr,
1422 const VerifyOption vo) const;
1423
1424 bool is_obj_dead_cond(const oop obj,
1425 const VerifyOption vo) const;
1426
1427 G1HeapSummary create_g1_heap_summary();
1428 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats);
1429
1430 // Printing
1431 private:
1432 void print_heap_regions() const;
1433 void print_regions_on(outputStream* st) const;
1434
1435 public:
1436 virtual void print_on(outputStream* st) const;
1437 virtual void print_extended_on(outputStream* st) const;
1438 virtual void print_on_error(outputStream* st) const;
1439
1440 virtual void print_gc_threads_on(outputStream* st) const;
1441 virtual void gc_threads_do(ThreadClosure* tc) const;
1442
1443 // Override
1444 void print_tracing_info() const;
1445
1446 // The following two methods are helpful for debugging RSet issues.
1447 void print_cset_rsets() PRODUCT_RETURN;
1448 void print_all_rsets() PRODUCT_RETURN;
1449
1450 // Used to print information about locations in the hs_err file.
1451 virtual bool print_location(outputStream* st, void* addr) const;
1452
1453 size_t pending_card_num();
1454 };
1455
1456 class G1ParEvacuateFollowersClosure : public VoidClosure {
1457 private:
1458 double _start_term;
1459 double _term_time;
1460 size_t _term_attempts;
1461
1462 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
1463 void end_term_time() { _term_time += (os::elapsedTime() - _start_term); }
1464 protected:
1465 G1CollectedHeap* _g1h;
1466 G1ParScanThreadState* _par_scan_state;
1467 RefToScanQueueSet* _queues;
1468 ParallelTaskTerminator* _terminator;
1469 G1GCPhaseTimes::GCParPhases _phase;
1470
1471 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
1472 RefToScanQueueSet* queues() { return _queues; }
1473 ParallelTaskTerminator* terminator() { return _terminator; }
1474
1475 public:
1476 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
1477 G1ParScanThreadState* par_scan_state,
1478 RefToScanQueueSet* queues,
1479 ParallelTaskTerminator* terminator,
1480 G1GCPhaseTimes::GCParPhases phase)
1481 : _start_term(0.0), _term_time(0.0), _term_attempts(0),
1482 _g1h(g1h), _par_scan_state(par_scan_state),
1483 _queues(queues), _terminator(terminator), _phase(phase) {}
1484
1485 void do_void();
1486
1487 double term_time() const { return _term_time; }
1488 size_t term_attempts() const { return _term_attempts; }
1489
1490 private:
1491 inline bool offer_termination();
1492 };
1493
1494 #endif // SHARE_GC_G1_G1COLLECTEDHEAP_HPP