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
13 * accompanied this code).
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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/g1HeapRegionAttr.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 G1Policy;
78 class G1HotCardCache;
79 class G1RemSet;
80 class G1YoungRemSetSamplingThread;
81 class HeapRegionRemSetIterator;
82 class G1ConcurrentMark;
83 class G1ConcurrentMarkThread;
84 class G1ConcurrentRefine;
85 class GenerationCounters;
86 class STWGCTimer;
87 class G1NewTracer;
88 class EvacuationFailedInfo;
89 class nmethod;
90 class WorkGang;
91 class G1Allocator;
92 class G1ArchiveAllocator;
93 class G1FullGCScope;
94 class G1HeapVerifier;
95 class G1HeapSizingPolicy;
96 class G1HeapSummary;
97 class G1EvacSummary;
98
99 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue;
100 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
101
102 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
103 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
104
105 // The G1 STW is alive closure.
106 // An instance is embedded into the G1CH and used as the
107 // (optional) _is_alive_non_header closure in the STW
108 // reference processor. It is also extensively used during
109 // reference processing during STW evacuation pauses.
110 class G1STWIsAliveClosure : public BoolObjectClosure {
111 G1CollectedHeap* _g1h;
112 public:
113 G1STWIsAliveClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
114 bool do_object_b(oop p);
115 };
116
117 class G1STWSubjectToDiscoveryClosure : public BoolObjectClosure {
118 G1CollectedHeap* _g1h;
119 public:
120 G1STWSubjectToDiscoveryClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
121 bool do_object_b(oop p);
122 };
123
124 class G1RegionMappingChangedListener : public G1MappingChangedListener {
125 private:
126 void reset_from_card_cache(uint start_idx, size_t num_regions);
127 public:
128 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
129 };
130
131 class G1CollectedHeap : public CollectedHeap {
132 friend class G1FreeCollectionSetTask;
133 friend class VM_CollectForMetadataAllocation;
134 friend class VM_G1CollectForAllocation;
135 friend class VM_G1CollectFull;
136 friend class VMStructs;
137 friend class MutatorAllocRegion;
138 friend class G1FullCollector;
139 friend class G1GCAllocRegion;
140 friend class G1HeapVerifier;
141
142 // Closures used in implementation.
143 friend class G1ParScanThreadState;
144 friend class G1ParScanThreadStateSet;
145 friend class G1EvacuateRegionsTask;
146 friend class G1PLABAllocator;
147
148 // Other related classes.
149 friend class HeapRegionClaimer;
150
151 // Testing classes.
152 friend class G1CheckRegionAttrTableClosure;
153
154 private:
155 G1YoungRemSetSamplingThread* _young_gen_sampling_thread;
156
157 WorkGang* _workers;
158 G1CardTable* _card_table;
159
160 SoftRefPolicy _soft_ref_policy;
161
162 static size_t _humongous_object_threshold_in_words;
163
164 // These sets keep track of old, archive and humongous regions respectively.
165 HeapRegionSet _old_set;
166 HeapRegionSet _archive_set;
167 HeapRegionSet _humongous_set;
168
169 void eagerly_reclaim_humongous_regions();
170 // Start a new incremental collection set for the next pause.
171 void start_new_collection_set();
172
173 // The block offset table for the G1 heap.
174 G1BlockOffsetTable* _bot;
175
176 // Tears down the region sets / lists so that they are empty and the
177 // regions on the heap do not belong to a region set / list. The
178 // only exception is the humongous set which we leave unaltered. If
179 // free_list_only is true, it will only tear down the master free
180 // list. It is called before a Full GC (free_list_only == false) or
181 // before heap shrinking (free_list_only == true).
182 void tear_down_region_sets(bool free_list_only);
183
184 // Rebuilds the region sets / lists so that they are repopulated to
185 // reflect the contents of the heap. The only exception is the
186 // humongous set which was not torn down in the first place. If
187 // free_list_only is true, it will only rebuild the master free
188 // list. It is called after a Full GC (free_list_only == false) or
189 // after heap shrinking (free_list_only == true).
190 void rebuild_region_sets(bool free_list_only);
191
192 // Callback for region mapping changed events.
193 G1RegionMappingChangedListener _listener;
194
195 // The sequence of all heap regions in the heap.
196 HeapRegionManager* _hrm;
197
198 // Manages all allocations with regions except humongous object allocations.
199 G1Allocator* _allocator;
200
201 // Manages all heap verification.
202 G1HeapVerifier* _verifier;
203
204 // Outside of GC pauses, the number of bytes used in all regions other
205 // than the current allocation region(s).
206 volatile size_t _summary_bytes_used;
207
208 void increase_used(size_t bytes);
209 void decrease_used(size_t bytes);
210
211 void set_used(size_t bytes);
212
213 // Class that handles archive allocation ranges.
214 G1ArchiveAllocator* _archive_allocator;
215
216 // GC allocation statistics policy for survivors.
217 G1EvacStats _survivor_evac_stats;
218
219 // GC allocation statistics policy for tenured objects.
220 G1EvacStats _old_evac_stats;
221
222 // It specifies whether we should attempt to expand the heap after a
223 // region allocation failure. If heap expansion fails we set this to
224 // false so that we don't re-attempt the heap expansion (it's likely
225 // that subsequent expansion attempts will also fail if one fails).
226 // Currently, it is only consulted during GC and it's reset at the
227 // start of each GC.
228 bool _expand_heap_after_alloc_failure;
229
230 // Helper for monitoring and management support.
231 G1MonitoringSupport* _g1mm;
232
233 // Records whether the region at the given index is (still) a
234 // candidate for eager reclaim. Only valid for humongous start
235 // regions; other regions have unspecified values. Humongous start
236 // regions are initialized at start of collection pause, with
237 // candidates removed from the set as they are found reachable from
238 // roots or the young generation.
239 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> {
240 protected:
241 bool default_value() const { return false; }
242 public:
243 void clear() { G1BiasedMappedArray<bool>::clear(); }
244 void set_candidate(uint region, bool value) {
245 set_by_index(region, value);
246 }
247 bool is_candidate(uint region) {
248 return get_by_index(region);
249 }
250 };
251
252 HumongousReclaimCandidates _humongous_reclaim_candidates;
253 // Stores whether during humongous object registration we found candidate regions.
254 // If not, we can skip a few steps.
255 bool _has_humongous_reclaim_candidates;
256
257 G1HRPrinter _hr_printer;
258
259 // It decides whether an explicit GC should start a concurrent cycle
260 // instead of doing a STW GC. Currently, a concurrent cycle is
261 // explicitly started if:
262 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
263 // (b) cause == _g1_humongous_allocation
264 // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
265 // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent.
266 // (e) cause == _wb_conc_mark
267 bool should_do_concurrent_full_gc(GCCause::Cause cause);
268
269 // Return true if should upgrade to full gc after an incremental one.
270 bool should_upgrade_to_full_gc(GCCause::Cause cause);
271
272 // indicates whether we are in young or mixed GC mode
273 G1CollectorState _collector_state;
274
275 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
276 // concurrent cycles) we have started.
277 volatile uint _old_marking_cycles_started;
278
279 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
280 // concurrent cycles) we have completed.
281 volatile uint _old_marking_cycles_completed;
282
283 // This is a non-product method that is helpful for testing. It is
284 // called at the end of a GC and artificially expands the heap by
285 // allocating a number of dead regions. This way we can induce very
286 // frequent marking cycles and stress the cleanup / concurrent
287 // cleanup code more (as all the regions that will be allocated by
288 // this method will be found dead by the marking cycle).
289 void allocate_dummy_regions() PRODUCT_RETURN;
290
291 // If the HR printer is active, dump the state of the regions in the
292 // heap after a compaction.
293 void print_hrm_post_compaction();
294
295 // Create a memory mapper for auxiliary data structures of the given size and
296 // translation factor.
297 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description,
298 size_t size,
299 size_t translation_factor);
300
301 void trace_heap(GCWhen::Type when, const GCTracer* tracer);
302
303 // These are macros so that, if the assert fires, we get the correct
304 // line number, file, etc.
305
306 #define heap_locking_asserts_params(_extra_message_) \
307 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
308 (_extra_message_), \
309 BOOL_TO_STR(Heap_lock->owned_by_self()), \
310 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
311 BOOL_TO_STR(Thread::current()->is_VM_thread())
312
313 #define assert_heap_locked() \
314 do { \
315 assert(Heap_lock->owned_by_self(), \
316 heap_locking_asserts_params("should be holding the Heap_lock")); \
317 } while (0)
318
319 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
320 do { \
321 assert(Heap_lock->owned_by_self() || \
322 (SafepointSynchronize::is_at_safepoint() && \
323 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
324 heap_locking_asserts_params("should be holding the Heap_lock or " \
325 "should be at a safepoint")); \
326 } while (0)
327
328 #define assert_heap_locked_and_not_at_safepoint() \
329 do { \
330 assert(Heap_lock->owned_by_self() && \
331 !SafepointSynchronize::is_at_safepoint(), \
332 heap_locking_asserts_params("should be holding the Heap_lock and " \
333 "should not be at a safepoint")); \
334 } while (0)
335
336 #define assert_heap_not_locked() \
337 do { \
338 assert(!Heap_lock->owned_by_self(), \
339 heap_locking_asserts_params("should not be holding the Heap_lock")); \
340 } while (0)
341
342 #define assert_heap_not_locked_and_not_at_safepoint() \
343 do { \
344 assert(!Heap_lock->owned_by_self() && \
345 !SafepointSynchronize::is_at_safepoint(), \
346 heap_locking_asserts_params("should not be holding the Heap_lock and " \
347 "should not be at a safepoint")); \
348 } while (0)
349
350 #define assert_at_safepoint_on_vm_thread() \
351 do { \
352 assert_at_safepoint(); \
353 assert(Thread::current_or_null() != NULL, "no current thread"); \
354 assert(Thread::current()->is_VM_thread(), "current thread is not VM thread"); \
355 } while (0)
356
357 #define assert_used_and_recalculate_used_equal(g1h) \
358 do { \
359 size_t cur_used_bytes = g1h->used(); \
360 size_t recal_used_bytes = g1h->recalculate_used(); \
361 assert(cur_used_bytes == recal_used_bytes, "Used(" SIZE_FORMAT ") is not" \
362 " same as recalculated used(" SIZE_FORMAT ").", \
363 cur_used_bytes, recal_used_bytes); \
364 } while (0)
365
366 const char* young_gc_name() const;
367
368 // The young region list.
369 G1EdenRegions _eden;
370 G1SurvivorRegions _survivor;
371
372 STWGCTimer* _gc_timer_stw;
373
374 G1NewTracer* _gc_tracer_stw;
375
376 // The current policy object for the collector.
377 G1Policy* _policy;
378 G1HeapSizingPolicy* _heap_sizing_policy;
379
380 G1CollectionSet _collection_set;
381
382 // Try to allocate a single non-humongous HeapRegion sufficient for
383 // an allocation of the given word_size. If do_expand is true,
384 // attempt to expand the heap if necessary to satisfy the allocation
385 // request. 'type' takes the type of region to be allocated. (Use constants
386 // Old, Eden, Humongous, Survivor defined in HeapRegionType.)
387 HeapRegion* new_region(size_t word_size, HeapRegionType type, bool do_expand);
388
389 // Initialize a contiguous set of free regions of length num_regions
390 // and starting at index first so that they appear as a single
391 // humongous region.
392 HeapWord* humongous_obj_allocate_initialize_regions(uint first,
393 uint num_regions,
394 size_t word_size);
395
396 // Attempt to allocate a humongous object of the given size. Return
397 // NULL if unsuccessful.
398 HeapWord* humongous_obj_allocate(size_t word_size);
399
400 // The following two methods, allocate_new_tlab() and
401 // mem_allocate(), are the two main entry points from the runtime
402 // into the G1's allocation routines. They have the following
403 // assumptions:
404 //
405 // * They should both be called outside safepoints.
406 //
407 // * They should both be called without holding the Heap_lock.
408 //
409 // * All allocation requests for new TLABs should go to
410 // allocate_new_tlab().
411 //
412 // * All non-TLAB allocation requests should go to mem_allocate().
413 //
414 // * If either call cannot satisfy the allocation request using the
415 // current allocating region, they will try to get a new one. If
416 // this fails, they will attempt to do an evacuation pause and
417 // retry the allocation.
418 //
419 // * If all allocation attempts fail, even after trying to schedule
420 // an evacuation pause, allocate_new_tlab() will return NULL,
421 // whereas mem_allocate() will attempt a heap expansion and/or
422 // schedule a Full GC.
423 //
424 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
425 // should never be called with word_size being humongous. All
426 // humongous allocation requests should go to mem_allocate() which
427 // will satisfy them with a special path.
428
429 virtual HeapWord* allocate_new_tlab(size_t min_size,
430 size_t requested_size,
431 size_t* actual_size);
432
433 virtual HeapWord* mem_allocate(size_t word_size,
434 bool* gc_overhead_limit_was_exceeded);
435
436 // First-level mutator allocation attempt: try to allocate out of
437 // the mutator alloc region without taking the Heap_lock. This
438 // should only be used for non-humongous allocations.
439 inline HeapWord* attempt_allocation(size_t min_word_size,
440 size_t desired_word_size,
441 size_t* actual_word_size);
442
443 // Second-level mutator allocation attempt: take the Heap_lock and
444 // retry the allocation attempt, potentially scheduling a GC
445 // pause. This should only be used for non-humongous allocations.
446 HeapWord* attempt_allocation_slow(size_t word_size);
447
448 // Takes the Heap_lock and attempts a humongous allocation. It can
449 // potentially schedule a GC pause.
450 HeapWord* attempt_allocation_humongous(size_t word_size);
451
452 // Allocation attempt that should be called during safepoints (e.g.,
453 // at the end of a successful GC). expect_null_mutator_alloc_region
454 // specifies whether the mutator alloc region is expected to be NULL
455 // or not.
456 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
457 bool expect_null_mutator_alloc_region);
458
459 // These methods are the "callbacks" from the G1AllocRegion class.
460
461 // For mutator alloc regions.
462 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
463 void retire_mutator_alloc_region(HeapRegion* alloc_region,
464 size_t allocated_bytes);
465
466 // For GC alloc regions.
467 bool has_more_regions(G1HeapRegionAttr dest);
468 HeapRegion* new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest);
469 void retire_gc_alloc_region(HeapRegion* alloc_region,
470 size_t allocated_bytes, G1HeapRegionAttr dest);
471
472 // - if explicit_gc is true, the GC is for a System.gc() etc,
473 // otherwise it's for a failed allocation.
474 // - if clear_all_soft_refs is true, all soft references should be
475 // cleared during the GC.
476 // - it returns false if it is unable to do the collection due to the
477 // GC locker being active, true otherwise.
478 bool do_full_collection(bool explicit_gc,
479 bool clear_all_soft_refs);
480
481 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread.
482 virtual void do_full_collection(bool clear_all_soft_refs);
483
484 // Callback from VM_G1CollectForAllocation operation.
485 // This function does everything necessary/possible to satisfy a
486 // failed allocation request (including collection, expansion, etc.)
487 HeapWord* satisfy_failed_allocation(size_t word_size,
488 bool* succeeded);
489 // Internal helpers used during full GC to split it up to
490 // increase readability.
491 void abort_concurrent_cycle();
492 void verify_before_full_collection(bool explicit_gc);
493 void prepare_heap_for_full_collection();
494 void prepare_heap_for_mutators();
495 void abort_refinement();
496 void verify_after_full_collection();
497 void print_heap_after_full_collection(G1HeapTransition* heap_transition);
498
499 // Helper method for satisfy_failed_allocation()
500 HeapWord* satisfy_failed_allocation_helper(size_t word_size,
501 bool do_gc,
502 bool clear_all_soft_refs,
503 bool expect_null_mutator_alloc_region,
504 bool* gc_succeeded);
505
506 // Attempting to expand the heap sufficiently
507 // to support an allocation of the given "word_size". If
508 // successful, perform the allocation and return the address of the
509 // allocated block, or else "NULL".
510 HeapWord* expand_and_allocate(size_t word_size);
511
512 // Process any reference objects discovered.
513 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states);
514
515 // If during an initial mark pause we may install a pending list head which is not
516 // otherwise reachable ensure that it is marked in the bitmap for concurrent marking
517 // to discover.
518 void make_pending_list_reachable();
519
520 // Merges the information gathered on a per-thread basis for all worker threads
521 // during GC into global variables.
522 void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states);
523 public:
524 G1YoungRemSetSamplingThread* sampling_thread() const { return _young_gen_sampling_thread; }
525
526 WorkGang* workers() const { return _workers; }
527
528 // Runs the given AbstractGangTask with the current active workers, returning the
529 // total time taken.
530 Tickspan run_task(AbstractGangTask* task);
531
532 G1Allocator* allocator() {
533 return _allocator;
534 }
535
536 G1HeapVerifier* verifier() {
537 return _verifier;
538 }
539
540 G1MonitoringSupport* g1mm() {
541 assert(_g1mm != NULL, "should have been initialized");
542 return _g1mm;
543 }
544
545 void resize_heap_if_necessary();
546
547 // Expand the garbage-first heap by at least the given size (in bytes!).
548 // Returns true if the heap was expanded by the requested amount;
549 // false otherwise.
550 // (Rounds up to a HeapRegion boundary.)
551 bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL);
552
553 // Returns the PLAB statistics for a given destination.
554 inline G1EvacStats* alloc_buffer_stats(G1HeapRegionAttr dest);
555
556 // Determines PLAB size for a given destination.
557 inline size_t desired_plab_sz(G1HeapRegionAttr dest);
558
559 // Do anything common to GC's.
560 void gc_prologue(bool full);
561 void gc_epilogue(bool full);
562
563 // Does the given region fulfill remembered set based eager reclaim candidate requirements?
564 bool is_potential_eager_reclaim_candidate(HeapRegion* r) const;
565
566 // Modify the reclaim candidate set and test for presence.
567 // These are only valid for starts_humongous regions.
568 inline void set_humongous_reclaim_candidate(uint region, bool value);
569 inline bool is_humongous_reclaim_candidate(uint region);
570
571 // Remove from the reclaim candidate set. Also remove from the
572 // collection set so that later encounters avoid the slow path.
573 inline void set_humongous_is_live(oop obj);
574
575 // Register the given region to be part of the collection set.
576 inline void register_humongous_region_with_region_attr(uint index);
577 // Update region attributes table with information about all regions.
578 void register_regions_with_region_attr();
579 // We register a region with the fast "in collection set" test. We
580 // simply set to true the array slot corresponding to this region.
581 void register_young_region_with_region_attr(HeapRegion* r) {
582 _region_attr.set_in_young(r->hrm_index());
583 }
584 inline void register_region_with_region_attr(HeapRegion* r);
585 inline void register_old_region_with_region_attr(HeapRegion* r);
586 inline void register_optional_region_with_region_attr(HeapRegion* r);
587
588 void clear_region_attr(const HeapRegion* hr) {
589 _region_attr.clear(hr);
590 }
591
592 void clear_region_attr() {
593 _region_attr.clear();
594 }
595
596 // Verify that the G1RegionAttr remset tracking corresponds to actual remset tracking
597 // for all regions.
598 void verify_region_attr_remset_update() PRODUCT_RETURN;
599
600 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause);
601
602 // This is called at the start of either a concurrent cycle or a Full
603 // GC to update the number of old marking cycles started.
604 void increment_old_marking_cycles_started();
605
606 // This is called at the end of either a concurrent cycle or a Full
607 // GC to update the number of old marking cycles completed. Those two
608 // can happen in a nested fashion, i.e., we start a concurrent
609 // cycle, a Full GC happens half-way through it which ends first,
610 // and then the cycle notices that a Full GC happened and ends
611 // too. The concurrent parameter is a boolean to help us do a bit
612 // tighter consistency checking in the method. If concurrent is
613 // false, the caller is the inner caller in the nesting (i.e., the
614 // Full GC). If concurrent is true, the caller is the outer caller
615 // in this nesting (i.e., the concurrent cycle). Further nesting is
616 // not currently supported. The end of this call also notifies
617 // the FullGCCount_lock in case a Java thread is waiting for a full
618 // GC to happen (e.g., it called System.gc() with
619 // +ExplicitGCInvokesConcurrent).
620 void increment_old_marking_cycles_completed(bool concurrent);
621
622 uint old_marking_cycles_completed() {
623 return _old_marking_cycles_completed;
624 }
625
626 G1HRPrinter* hr_printer() { return &_hr_printer; }
627
628 // Allocates a new heap region instance.
629 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr);
630
631 // Allocate the highest free region in the reserved heap. This will commit
632 // regions as necessary.
633 HeapRegion* alloc_highest_free_region();
634
635 // Frees a non-humongous region by initializing its contents and
636 // adding it to the free list that's passed as a parameter (this is
637 // usually a local list which will be appended to the master free
638 // list later). The used bytes of freed regions are accumulated in
639 // pre_used. If skip_remset is true, the region's RSet will not be freed
640 // up. If skip_hot_card_cache is true, the region's hot card cache will not
641 // be freed up. The assumption is that this will be done later.
642 // The locked parameter indicates if the caller has already taken
643 // care of proper synchronization. This may allow some optimizations.
644 void free_region(HeapRegion* hr,
645 FreeRegionList* free_list,
646 bool skip_remset,
647 bool skip_hot_card_cache = false,
648 bool locked = false);
649
650 // It dirties the cards that cover the block so that the post
651 // write barrier never queues anything when updating objects on this
652 // block. It is assumed (and in fact we assert) that the block
653 // belongs to a young region.
654 inline void dirty_young_block(HeapWord* start, size_t word_size);
655
656 // Frees a humongous region by collapsing it into individual regions
657 // and calling free_region() for each of them. The freed regions
658 // will be added to the free list that's passed as a parameter (this
659 // is usually a local list which will be appended to the master free
660 // list later).
661 // The method assumes that only a single thread is ever calling
662 // this for a particular region at once.
663 void free_humongous_region(HeapRegion* hr,
664 FreeRegionList* free_list);
665
666 // Facility for allocating in 'archive' regions in high heap memory and
667 // recording the allocated ranges. These should all be called from the
668 // VM thread at safepoints, without the heap lock held. They can be used
669 // to create and archive a set of heap regions which can be mapped at the
670 // same fixed addresses in a subsequent JVM invocation.
671 void begin_archive_alloc_range(bool open = false);
672
673 // Check if the requested size would be too large for an archive allocation.
674 bool is_archive_alloc_too_large(size_t word_size);
675
676 // Allocate memory of the requested size from the archive region. This will
677 // return NULL if the size is too large or if no memory is available. It
678 // does not trigger a garbage collection.
679 HeapWord* archive_mem_allocate(size_t word_size);
680
681 // Optionally aligns the end address and returns the allocated ranges in
682 // an array of MemRegions in order of ascending addresses.
683 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
684 size_t end_alignment_in_bytes = 0);
685
686 // Facility for allocating a fixed range within the heap and marking
687 // the containing regions as 'archive'. For use at JVM init time, when the
688 // caller may mmap archived heap data at the specified range(s).
689 // Verify that the MemRegions specified in the argument array are within the
690 // reserved heap.
691 bool check_archive_addresses(MemRegion* range, size_t count);
692
693 // Commit the appropriate G1 regions containing the specified MemRegions
694 // and mark them as 'archive' regions. The regions in the array must be
695 // non-overlapping and in order of ascending address.
696 bool alloc_archive_regions(MemRegion* range, size_t count, bool open);
697
698 // Insert any required filler objects in the G1 regions around the specified
699 // ranges to make the regions parseable. This must be called after
700 // alloc_archive_regions, and after class loading has occurred.
701 void fill_archive_regions(MemRegion* range, size_t count);
702
703 // For each of the specified MemRegions, uncommit the containing G1 regions
704 // which had been allocated by alloc_archive_regions. This should be called
705 // rather than fill_archive_regions at JVM init time if the archive file
706 // mapping failed, with the same non-overlapping and sorted MemRegion array.
707 void dealloc_archive_regions(MemRegion* range, size_t count, bool is_open);
708
709 oop materialize_archived_object(oop obj);
710
711 private:
712
713 // Shrink the garbage-first heap by at most the given size (in bytes!).
714 // (Rounds down to a HeapRegion boundary.)
715 void shrink(size_t expand_bytes);
716 void shrink_helper(size_t expand_bytes);
717
718 #if TASKQUEUE_STATS
719 static void print_taskqueue_stats_hdr(outputStream* const st);
720 void print_taskqueue_stats() const;
721 void reset_taskqueue_stats();
722 #endif // TASKQUEUE_STATS
723
724 // Schedule the VM operation that will do an evacuation pause to
725 // satisfy an allocation request of word_size. *succeeded will
726 // return whether the VM operation was successful (it did do an
727 // evacuation pause) or not (another thread beat us to it or the GC
728 // locker was active). Given that we should not be holding the
729 // Heap_lock when we enter this method, we will pass the
730 // gc_count_before (i.e., total_collections()) as a parameter since
731 // it has to be read while holding the Heap_lock. Currently, both
732 // methods that call do_collection_pause() release the Heap_lock
733 // before the call, so it's easy to read gc_count_before just before.
734 HeapWord* do_collection_pause(size_t word_size,
735 uint gc_count_before,
736 bool* succeeded,
737 GCCause::Cause gc_cause);
738
739 void wait_for_root_region_scanning();
740
741 // The guts of the incremental collection pause, executed by the vm
742 // thread. It returns false if it is unable to do the collection due
743 // to the GC locker being active, true otherwise
744 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
745
746 G1HeapVerifier::G1VerifyType young_collection_verify_type() const;
747 void verify_before_young_collection(G1HeapVerifier::G1VerifyType type);
748 void verify_after_young_collection(G1HeapVerifier::G1VerifyType type);
749
750 void calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms);
751
752 // Actually do the work of evacuating the parts of the collection set.
753 void evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states);
754 void evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states);
755 private:
756 // Evacuate the next set of optional regions.
757 void evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states);
758
759 public:
760 void pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info);
761 void post_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss);
762
763 void expand_heap_after_young_collection();
764 // Update object copying statistics.
765 void record_obj_copy_mem_stats();
766
767 // The hot card cache for remembered set insertion optimization.
768 G1HotCardCache* _hot_card_cache;
769
770 // The g1 remembered set of the heap.
771 G1RemSet* _rem_set;
772
773 // A set of cards that cover the objects for which the Rsets should be updated
774 // concurrently after the collection.
775 G1DirtyCardQueueSet _dirty_card_queue_set;
776
777 // After a collection pause, convert the regions in the collection set into free
778 // regions.
779 void free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words);
780
781 // Abandon the current collection set without recording policy
782 // statistics or updating free lists.
783 void abandon_collection_set(G1CollectionSet* collection_set);
784
785 // The concurrent marker (and the thread it runs in.)
786 G1ConcurrentMark* _cm;
787 G1ConcurrentMarkThread* _cm_thread;
788
789 // The concurrent refiner.
790 G1ConcurrentRefine* _cr;
791
792 // The parallel task queues
793 RefToScanQueueSet *_task_queues;
794
795 // True iff a evacuation has failed in the current collection.
796 bool _evacuation_failed;
797
798 EvacuationFailedInfo* _evacuation_failed_info_array;
799
800 // Failed evacuations cause some logical from-space objects to have
801 // forwarding pointers to themselves. Reset them.
802 void remove_self_forwarding_pointers();
803
804 // Restore the objects in the regions in the collection set after an
805 // evacuation failure.
806 void restore_after_evac_failure();
807
808 PreservedMarksSet _preserved_marks_set;
809
810 // Preserve the mark of "obj", if necessary, in preparation for its mark
811 // word being overwritten with a self-forwarding-pointer.
812 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m);
813
814 #ifndef PRODUCT
815 // Support for forcing evacuation failures. Analogous to
816 // PromotionFailureALot for the other collectors.
817
818 // Records whether G1EvacuationFailureALot should be in effect
819 // for the current GC
820 bool _evacuation_failure_alot_for_current_gc;
821
822 // Used to record the GC number for interval checking when
823 // determining whether G1EvaucationFailureALot is in effect
824 // for the current GC.
825 size_t _evacuation_failure_alot_gc_number;
826
827 // Count of the number of evacuations between failures.
828 volatile size_t _evacuation_failure_alot_count;
829
830 // Set whether G1EvacuationFailureALot should be in effect
831 // for the current GC (based upon the type of GC and which
832 // command line flags are set);
833 inline bool evacuation_failure_alot_for_gc_type(bool for_young_gc,
834 bool during_initial_mark,
835 bool mark_or_rebuild_in_progress);
836
837 inline void set_evacuation_failure_alot_for_current_gc();
838
839 // Return true if it's time to cause an evacuation failure.
840 inline bool evacuation_should_fail();
841
842 // Reset the G1EvacuationFailureALot counters. Should be called at
843 // the end of an evacuation pause in which an evacuation failure occurred.
844 inline void reset_evacuation_should_fail();
845 #endif // !PRODUCT
846
847 // ("Weak") Reference processing support.
848 //
849 // G1 has 2 instances of the reference processor class. One
850 // (_ref_processor_cm) handles reference object discovery
851 // and subsequent processing during concurrent marking cycles.
852 //
853 // The other (_ref_processor_stw) handles reference object
854 // discovery and processing during full GCs and incremental
855 // evacuation pauses.
856 //
857 // During an incremental pause, reference discovery will be
858 // temporarily disabled for _ref_processor_cm and will be
859 // enabled for _ref_processor_stw. At the end of the evacuation
860 // pause references discovered by _ref_processor_stw will be
861 // processed and discovery will be disabled. The previous
862 // setting for reference object discovery for _ref_processor_cm
863 // will be re-instated.
864 //
865 // At the start of marking:
866 // * Discovery by the CM ref processor is verified to be inactive
867 // and it's discovered lists are empty.
868 // * Discovery by the CM ref processor is then enabled.
869 //
870 // At the end of marking:
871 // * Any references on the CM ref processor's discovered
872 // lists are processed (possibly MT).
873 //
874 // At the start of full GC we:
875 // * Disable discovery by the CM ref processor and
876 // empty CM ref processor's discovered lists
877 // (without processing any entries).
878 // * Verify that the STW ref processor is inactive and it's
879 // discovered lists are empty.
880 // * Temporarily set STW ref processor discovery as single threaded.
881 // * Temporarily clear the STW ref processor's _is_alive_non_header
882 // field.
883 // * Finally enable discovery by the STW ref processor.
884 //
885 // The STW ref processor is used to record any discovered
886 // references during the full GC.
887 //
888 // At the end of a full GC we:
889 // * Enqueue any reference objects discovered by the STW ref processor
890 // that have non-live referents. This has the side-effect of
891 // making the STW ref processor inactive by disabling discovery.
892 // * Verify that the CM ref processor is still inactive
893 // and no references have been placed on it's discovered
894 // lists (also checked as a precondition during initial marking).
895
896 // The (stw) reference processor...
897 ReferenceProcessor* _ref_processor_stw;
898
899 // During reference object discovery, the _is_alive_non_header
900 // closure (if non-null) is applied to the referent object to
901 // determine whether the referent is live. If so then the
902 // reference object does not need to be 'discovered' and can
903 // be treated as a regular oop. This has the benefit of reducing
904 // the number of 'discovered' reference objects that need to
905 // be processed.
906 //
907 // Instance of the is_alive closure for embedding into the
908 // STW reference processor as the _is_alive_non_header field.
909 // Supplying a value for the _is_alive_non_header field is
910 // optional but doing so prevents unnecessary additions to
911 // the discovered lists during reference discovery.
912 G1STWIsAliveClosure _is_alive_closure_stw;
913
914 G1STWSubjectToDiscoveryClosure _is_subject_to_discovery_stw;
915
916 // The (concurrent marking) reference processor...
917 ReferenceProcessor* _ref_processor_cm;
918
919 // Instance of the concurrent mark is_alive closure for embedding
920 // into the Concurrent Marking reference processor as the
921 // _is_alive_non_header field. Supplying a value for the
922 // _is_alive_non_header field is optional but doing so prevents
923 // unnecessary additions to the discovered lists during reference
924 // discovery.
925 G1CMIsAliveClosure _is_alive_closure_cm;
926
927 G1CMSubjectToDiscoveryClosure _is_subject_to_discovery_cm;
928 public:
929
930 RefToScanQueue *task_queue(uint i) const;
931
932 uint num_task_queues() const;
933
934 // A set of cards where updates happened during the GC
935 G1DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
936
937 // Create a G1CollectedHeap.
938 // Must call the initialize method afterwards.
939 // May not return if something goes wrong.
940 G1CollectedHeap();
941
942 private:
943 jint initialize_concurrent_refinement();
944 jint initialize_young_gen_sampling_thread();
945 public:
946 // Initialize the G1CollectedHeap to have the initial and
947 // maximum sizes and remembered and barrier sets
948 // specified by the policy object.
949 jint initialize();
950
951 virtual void stop();
952 virtual void safepoint_synchronize_begin();
953 virtual void safepoint_synchronize_end();
954
955 // Does operations required after initialization has been done.
956 void post_initialize();
957
958 // Initialize weak reference processing.
959 void ref_processing_init();
960
961 virtual Name kind() const {
962 return CollectedHeap::G1;
963 }
964
965 virtual const char* name() const {
966 return "G1";
967 }
968
969 const G1CollectorState* collector_state() const { return &_collector_state; }
970 G1CollectorState* collector_state() { return &_collector_state; }
971
972 // The current policy object for the collector.
973 G1Policy* policy() const { return _policy; }
974 // The remembered set.
975 G1RemSet* rem_set() const { return _rem_set; }
976
977 inline G1GCPhaseTimes* phase_times() const;
978
979 HeapRegionManager* hrm() const { return _hrm; }
980
981 const G1CollectionSet* collection_set() const { return &_collection_set; }
982 G1CollectionSet* collection_set() { return &_collection_set; }
983
984 virtual SoftRefPolicy* soft_ref_policy();
985
986 virtual void initialize_serviceability();
987 virtual MemoryUsage memory_usage();
988 virtual GrowableArray<GCMemoryManager*> memory_managers();
989 virtual GrowableArray<MemoryPool*> memory_pools();
990
991 // Try to minimize the remembered set.
992 void scrub_rem_set();
993
994 // Apply the given closure on all cards in the Hot Card Cache, emptying it.
995 void iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_i);
996
997 // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it.
998 void iterate_dirty_card_closure(G1CardTableEntryClosure* cl, uint worker_i);
999
1000 // The shared block offset table array.
1001 G1BlockOffsetTable* bot() const { return _bot; }
1002
1003 // Reference Processing accessors
1004
1005 // The STW reference processor....
1006 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1007
1008 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; }
1009
1010 // The Concurrent Marking reference processor...
1011 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1012
1013 size_t unused_committed_regions_in_bytes() const;
1014
1015 virtual size_t capacity() const;
1016 virtual size_t used() const;
1017 // This should be called when we're not holding the heap lock. The
1018 // result might be a bit inaccurate.
1019 size_t used_unlocked() const;
1020 size_t recalculate_used() const;
1021
1022 // These virtual functions do the actual allocation.
1023 // Some heaps may offer a contiguous region for shared non-blocking
1024 // allocation, via inlined code (by exporting the address of the top and
1025 // end fields defining the extent of the contiguous allocation region.)
1026 // But G1CollectedHeap doesn't yet support this.
1027
1028 virtual bool is_maximal_no_gc() const {
1029 return _hrm->available() == 0;
1030 }
1031
1032 // Returns whether there are any regions left in the heap for allocation.
1033 bool has_regions_left_for_allocation() const {
1034 return !is_maximal_no_gc() || num_free_regions() != 0;
1035 }
1036
1037 // The current number of regions in the heap.
1038 uint num_regions() const { return _hrm->length(); }
1039
1040 // The max number of regions in the heap.
1041 uint max_regions() const { return _hrm->max_length(); }
1042
1043 // Max number of regions that can be comitted.
1044 uint max_expandable_regions() const { return _hrm->max_expandable_length(); }
1045
1046 // The number of regions that are completely free.
1047 uint num_free_regions() const { return _hrm->num_free_regions(); }
1048
1049 // The number of regions that can be allocated into.
1050 uint num_free_or_available_regions() const { return num_free_regions() + _hrm->available(); }
1051
1052 MemoryUsage get_auxiliary_data_memory_usage() const {
1053 return _hrm->get_auxiliary_data_memory_usage();
1054 }
1055
1056 // The number of regions that are not completely free.
1057 uint num_used_regions() const { return num_regions() - num_free_regions(); }
1058
1059 #ifdef ASSERT
1060 bool is_on_master_free_list(HeapRegion* hr) {
1061 return _hrm->is_free(hr);
1062 }
1063 #endif // ASSERT
1064
1065 inline void old_set_add(HeapRegion* hr);
1066 inline void old_set_remove(HeapRegion* hr);
1067
1068 inline void archive_set_add(HeapRegion* hr);
1069
1070 size_t non_young_capacity_bytes() {
1071 return (old_regions_count() + _archive_set.length() + humongous_regions_count()) * HeapRegion::GrainBytes;
1072 }
1073
1074 // Determine whether the given region is one that we are using as an
1075 // old GC alloc region.
1076 bool is_old_gc_alloc_region(HeapRegion* hr);
1077
1078 // Perform a collection of the heap; intended for use in implementing
1079 // "System.gc". This probably implies as full a collection as the
1080 // "CollectedHeap" supports.
1081 virtual void collect(GCCause::Cause cause);
1082
1083 // Perform a collection of the heap with the given cause; if the VM operation
1084 // fails to execute for any reason, retry only if retry_on_gc_failure is set.
1085 // Returns whether this collection actually executed.
1086 bool try_collect(GCCause::Cause cause, bool retry_on_gc_failure);
1087
1088 // True iff an evacuation has failed in the most-recent collection.
1089 bool evacuation_failed() { return _evacuation_failed; }
1090
1091 void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed);
1092 void prepend_to_freelist(FreeRegionList* list);
1093 void decrement_summary_bytes(size_t bytes);
1094
1095 virtual bool is_in(const void* p) const;
1096 #ifdef ASSERT
1097 // Returns whether p is in one of the available areas of the heap. Slow but
1098 // extensive version.
1099 bool is_in_exact(const void* p) const;
1100 #endif
1101
1102 // Return "TRUE" iff the given object address is within the collection
1103 // set. Assumes that the reference points into the heap.
1104 inline bool is_in_cset(const HeapRegion *hr);
1105 inline bool is_in_cset(oop obj);
1106 inline bool is_in_cset(HeapWord* addr);
1107
1108 inline bool is_in_cset_or_humongous(const oop obj);
1109
1110 private:
1111 // This array is used for a quick test on whether a reference points into
1112 // the collection set or not. Each of the array's elements denotes whether the
1113 // corresponding region is in the collection set or not.
1114 G1HeapRegionAttrBiasedMappedArray _region_attr;
1115
1116 public:
1117
1118 inline G1HeapRegionAttr region_attr(const void* obj);
1119
1120 // Return "TRUE" iff the given object address is in the reserved
1121 // region of g1.
1122 bool is_in_g1_reserved(const void* p) const {
1123 return _hrm->reserved().contains(p);
1124 }
1125
1126 // Returns a MemRegion that corresponds to the space that has been
1127 // reserved for the heap
1128 MemRegion g1_reserved() const {
1129 return _hrm->reserved();
1130 }
1131
1132 G1HotCardCache* g1_hot_card_cache() const { return _hot_card_cache; }
1133
1134 G1CardTable* card_table() const {
1135 return _card_table;
1136 }
1137
1138 // Iteration functions.
1139
1140 // Iterate over all objects, calling "cl.do_object" on each.
1141 virtual void object_iterate(ObjectClosure* cl);
1142
1143 virtual void safe_object_iterate(ObjectClosure* cl) {
1144 object_iterate(cl);
1145 }
1146
1147 // Iterate over heap regions, in address order, terminating the
1148 // iteration early if the "do_heap_region" method returns "true".
1149 void heap_region_iterate(HeapRegionClosure* blk) const;
1150
1151 // Return the region with the given index. It assumes the index is valid.
1152 inline HeapRegion* region_at(uint index) const;
1153 inline HeapRegion* region_at_or_null(uint index) const;
1154
1155 // Return the next region (by index) that is part of the same
1156 // humongous object that hr is part of.
1157 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const;
1158
1159 // Calculate the region index of the given address. Given address must be
1160 // within the heap.
1161 inline uint addr_to_region(HeapWord* addr) const;
1162
1163 inline HeapWord* bottom_addr_for_region(uint index) const;
1164
1165 // Two functions to iterate over the heap regions in parallel. Threads
1166 // compete using the HeapRegionClaimer to claim the regions before
1167 // applying the closure on them.
1168 // The _from_worker_offset version uses the HeapRegionClaimer and
1169 // the worker id to calculate a start offset to prevent all workers to
1170 // start from the point.
1171 void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
1172 HeapRegionClaimer* hrclaimer,
1173 uint worker_id) const;
1174
1175 void heap_region_par_iterate_from_start(HeapRegionClosure* cl,
1176 HeapRegionClaimer* hrclaimer) const;
1177
1178 // Iterate over all regions currently in the current collection set.
1179 void collection_set_iterate_all(HeapRegionClosure* blk);
1180
1181 // Iterate over the regions in the current increment of the collection set.
1182 // Starts the iteration so that the start regions of a given worker id over the
1183 // set active_workers are evenly spread across the set of collection set regions
1184 // to be iterated.
1185 void collection_set_iterate_increment_from(HeapRegionClosure *blk, uint worker_id);
1186
1187 // Returns the HeapRegion that contains addr. addr must not be NULL.
1188 template <class T>
1189 inline HeapRegion* heap_region_containing(const T addr) const;
1190
1191 // Returns the HeapRegion that contains addr, or NULL if that is an uncommitted
1192 // region. addr must not be NULL.
1193 template <class T>
1194 inline HeapRegion* heap_region_containing_or_null(const T addr) const;
1195
1196 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1197 // each address in the (reserved) heap is a member of exactly
1198 // one block. The defining characteristic of a block is that it is
1199 // possible to find its size, and thus to progress forward to the next
1200 // block. (Blocks may be of different sizes.) Thus, blocks may
1201 // represent Java objects, or they might be free blocks in a
1202 // free-list-based heap (or subheap), as long as the two kinds are
1203 // distinguishable and the size of each is determinable.
1204
1205 // Returns the address of the start of the "block" that contains the
1206 // address "addr". We say "blocks" instead of "object" since some heaps
1207 // may not pack objects densely; a chunk may either be an object or a
1208 // non-object.
1209 virtual HeapWord* block_start(const void* addr) const;
1210
1211 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1212 // the block is an object.
1213 virtual bool block_is_obj(const HeapWord* addr) const;
1214
1215 // Section on thread-local allocation buffers (TLABs)
1216 // See CollectedHeap for semantics.
1217
1218 bool supports_tlab_allocation() const;
1219 size_t tlab_capacity(Thread* ignored) const;
1220 size_t tlab_used(Thread* ignored) const;
1221 size_t max_tlab_size() const;
1222 size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1223
1224 inline bool is_in_young(const oop obj);
1225
1226 // Returns "true" iff the given word_size is "very large".
1227 static bool is_humongous(size_t word_size) {
1228 // Note this has to be strictly greater-than as the TLABs
1229 // are capped at the humongous threshold and we want to
1230 // ensure that we don't try to allocate a TLAB as
1231 // humongous and that we don't allocate a humongous
1232 // object in a TLAB.
1233 return word_size > _humongous_object_threshold_in_words;
1234 }
1235
1236 // Returns the humongous threshold for a specific region size
1237 static size_t humongous_threshold_for(size_t region_size) {
1238 return (region_size / 2);
1239 }
1240
1241 // Returns the number of regions the humongous object of the given word size
1242 // requires.
1243 static size_t humongous_obj_size_in_regions(size_t word_size);
1244
1245 // Print the maximum heap capacity.
1246 virtual size_t max_capacity() const;
1247
1248 // Return the size of reserved memory. Returns different value than max_capacity() when AllocateOldGenAt is used.
1249 virtual size_t max_reserved_capacity() const;
1250
1251 virtual jlong millis_since_last_gc();
1252
1253
1254 // Convenience function to be used in situations where the heap type can be
1255 // asserted to be this type.
1256 static G1CollectedHeap* heap();
1257
1258 void set_region_short_lived_locked(HeapRegion* hr);
1259 // add appropriate methods for any other surv rate groups
1260
1261 const G1SurvivorRegions* survivor() const { return &_survivor; }
1262
1263 uint eden_regions_count() const { return _eden.length(); }
1264 uint survivor_regions_count() const { return _survivor.length(); }
1265 size_t eden_regions_used_bytes() const { return _eden.used_bytes(); }
1266 size_t survivor_regions_used_bytes() const { return _survivor.used_bytes(); }
1267 uint young_regions_count() const { return _eden.length() + _survivor.length(); }
1268 uint old_regions_count() const { return _old_set.length(); }
1269 uint archive_regions_count() const { return _archive_set.length(); }
1270 uint humongous_regions_count() const { return _humongous_set.length(); }
1271
1272 #ifdef ASSERT
1273 bool check_young_list_empty();
1274 #endif
1275
1276 // *** Stuff related to concurrent marking. It's not clear to me that so
1277 // many of these need to be public.
1278
1279 // The functions below are helper functions that a subclass of
1280 // "CollectedHeap" can use in the implementation of its virtual
1281 // functions.
1282 // This performs a concurrent marking of the live objects in a
1283 // bitmap off to the side.
1284 void do_concurrent_mark();
1285
1286 bool is_marked_next(oop obj) const;
1287
1288 // Determine if an object is dead, given the object and also
1289 // the region to which the object belongs. An object is dead
1290 // iff a) it was not allocated since the last mark, b) it
1291 // is not marked, and c) it is not in an archive region.
1292 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1293 return
1294 hr->is_obj_dead(obj, _cm->prev_mark_bitmap()) &&
1295 !hr->is_archive();
1296 }
1297
1298 // This function returns true when an object has been
1299 // around since the previous marking and hasn't yet
1300 // been marked during this marking, and is not in an archive region.
1301 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1302 return
1303 !hr->obj_allocated_since_next_marking(obj) &&
1304 !is_marked_next(obj) &&
1305 !hr->is_archive();
1306 }
1307
1308 // Determine if an object is dead, given only the object itself.
1309 // This will find the region to which the object belongs and
1310 // then call the region version of the same function.
1311
1312 // Added if it is NULL it isn't dead.
1313
1314 inline bool is_obj_dead(const oop obj) const;
1315
1316 inline bool is_obj_ill(const oop obj) const;
1317
1318 inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const;
1319 inline bool is_obj_dead_full(const oop obj) const;
1320
1321 G1ConcurrentMark* concurrent_mark() const { return _cm; }
1322
1323 // Refinement
1324
1325 G1ConcurrentRefine* concurrent_refine() const { return _cr; }
1326
1327 // Optimized nmethod scanning support routines
1328
1329 // Register the given nmethod with the G1 heap.
1330 virtual void register_nmethod(nmethod* nm);
1331
1332 // Unregister the given nmethod from the G1 heap.
1333 virtual void unregister_nmethod(nmethod* nm);
1334
1335 // No nmethod flushing needed.
1336 virtual void flush_nmethod(nmethod* nm) {}
1337
1338 // No nmethod verification implemented.
1339 virtual void verify_nmethod(nmethod* nm) {}
1340
1341 // Free up superfluous code root memory.
1342 void purge_code_root_memory();
1343
1344 // Rebuild the strong code root lists for each region
1345 // after a full GC.
1346 void rebuild_strong_code_roots();
1347
1348 // Partial cleaning of VM internal data structures.
1349 void string_dedup_cleaning(BoolObjectClosure* is_alive,
1350 OopClosure* keep_alive,
1351 G1GCPhaseTimes* phase_times = NULL);
1352
1353 // Performs cleaning of data structures after class unloading.
1354 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred);
1355
1356 // Redirty logged cards in the refinement queue.
1357 void redirty_logged_cards();
1358 // Verification
1359
1360 // Deduplicate the string
1361 virtual void deduplicate_string(oop str);
1362
1363 // Perform any cleanup actions necessary before allowing a verification.
1364 virtual void prepare_for_verify();
1365
1366 // Perform verification.
1367
1368 // vo == UsePrevMarking -> use "prev" marking information,
1369 // vo == UseNextMarking -> use "next" marking information
1370 // vo == UseFullMarking -> use "next" marking bitmap but no TAMS
1371 //
1372 // NOTE: Only the "prev" marking information is guaranteed to be
1373 // consistent most of the time, so most calls to this should use
1374 // vo == UsePrevMarking.
1375 // Currently, there is only one case where this is called with
1376 // vo == UseNextMarking, which is to verify the "next" marking
1377 // information at the end of remark.
1378 // Currently there is only one place where this is called with
1379 // vo == UseFullMarking, which is to verify the marking during a
1380 // full GC.
1381 void verify(VerifyOption vo);
1382
1383 // WhiteBox testing support.
1384 virtual bool supports_concurrent_phase_control() const;
1385 virtual bool request_concurrent_phase(const char* phase);
1386 bool is_heterogeneous_heap() const;
1387
1388 virtual WorkGang* get_safepoint_workers() { return _workers; }
1389
1390 // The methods below are here for convenience and dispatch the
1391 // appropriate method depending on value of the given VerifyOption
1392 // parameter. The values for that parameter, and their meanings,
1393 // are the same as those above.
1394
1395 bool is_obj_dead_cond(const oop obj,
1396 const HeapRegion* hr,
1397 const VerifyOption vo) const;
1398
1399 bool is_obj_dead_cond(const oop obj,
1400 const VerifyOption vo) const;
1401
1402 G1HeapSummary create_g1_heap_summary();
1403 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats);
1404
1405 // Printing
1406 private:
1407 void print_heap_regions() const;
1408 void print_regions_on(outputStream* st) const;
1409
1410 public:
1411 virtual void print_on(outputStream* st) const;
1412 virtual void print_extended_on(outputStream* st) const;
1413 virtual void print_on_error(outputStream* st) const;
1414
1415 virtual void print_gc_threads_on(outputStream* st) const;
1416 virtual void gc_threads_do(ThreadClosure* tc) const;
1417
1418 // Override
1419 void print_tracing_info() const;
1420
1421 // The following two methods are helpful for debugging RSet issues.
1422 void print_cset_rsets() PRODUCT_RETURN;
1423 void print_all_rsets() PRODUCT_RETURN;
1424
1425 size_t pending_card_num();
1426 };
1427
1428 class G1ParEvacuateFollowersClosure : public VoidClosure {
1429 private:
1430 double _start_term;
1431 double _term_time;
1432 size_t _term_attempts;
1433
1434 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
1435 void end_term_time() { _term_time += (os::elapsedTime() - _start_term); }
1436 protected:
1437 G1CollectedHeap* _g1h;
1438 G1ParScanThreadState* _par_scan_state;
1439 RefToScanQueueSet* _queues;
1440 ParallelTaskTerminator* _terminator;
1441 G1GCPhaseTimes::GCParPhases _phase;
1442
1443 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
1444 RefToScanQueueSet* queues() { return _queues; }
1445 ParallelTaskTerminator* terminator() { return _terminator; }
1446
1447 public:
1448 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
1449 G1ParScanThreadState* par_scan_state,
1450 RefToScanQueueSet* queues,
1451 ParallelTaskTerminator* terminator,
1452 G1GCPhaseTimes::GCParPhases phase)
1453 : _start_term(0.0), _term_time(0.0), _term_attempts(0),
1454 _g1h(g1h), _par_scan_state(par_scan_state),
1455 _queues(queues), _terminator(terminator), _phase(phase) {}
1456
1457 void do_void();
1458
1459 double term_time() const { return _term_time; }
1460 size_t term_attempts() const { return _term_attempts; }
1461
1462 private:
1463 inline bool offer_termination();
1464 };
1465
1466 #endif // SHARE_GC_G1_G1COLLECTEDHEAP_HPP