1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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24
25 #ifndef SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP
26 #define SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP
27
28 #include "gc/g1/evacuationInfo.hpp"
29 #include "gc/g1/g1BarrierSet.hpp"
30 #include "gc/g1/g1BiasedArray.hpp"
31 #include "gc/g1/g1CardTable.hpp"
32 #include "gc/g1/g1CollectionSet.hpp"
33 #include "gc/g1/g1CollectorState.hpp"
34 #include "gc/g1/g1ConcurrentMark.hpp"
35 #include "gc/g1/g1EdenRegions.hpp"
36 #include "gc/g1/g1EvacFailure.hpp"
37 #include "gc/g1/g1EvacStats.hpp"
38 #include "gc/g1/g1HeapTransition.hpp"
39 #include "gc/g1/g1HeapVerifier.hpp"
40 #include "gc/g1/g1HRPrinter.hpp"
41 #include "gc/g1/g1InCSetState.hpp"
42 #include "gc/g1/g1MonitoringSupport.hpp"
43 #include "gc/g1/g1SurvivorRegions.hpp"
44 #include "gc/g1/g1YCTypes.hpp"
45 #include "gc/g1/heapRegionManager.hpp"
46 #include "gc/g1/heapRegionSet.hpp"
47 #include "gc/shared/barrierSet.hpp"
48 #include "gc/shared/collectedHeap.hpp"
49 #include "gc/shared/gcHeapSummary.hpp"
50 #include "gc/shared/plab.hpp"
51 #include "gc/shared/preservedMarks.hpp"
52 #include "gc/shared/softRefPolicy.hpp"
53 #include "memory/memRegion.hpp"
54 #include "services/memoryManager.hpp"
55 #include "utilities/stack.hpp"
56
57 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
58 // It uses the "Garbage First" heap organization and algorithm, which
59 // may combine concurrent marking with parallel, incremental compaction of
60 // heap subsets that will yield large amounts of garbage.
61
62 // Forward declarations
63 class HeapRegion;
64 class HRRSCleanupTask;
65 class GenerationSpec;
66 class G1ParScanThreadState;
67 class G1ParScanThreadStateSet;
68 class G1ParScanThreadState;
69 class MemoryPool;
70 class ObjectClosure;
71 class SpaceClosure;
72 class CompactibleSpaceClosure;
73 class Space;
74 class G1CollectionSet;
75 class G1CollectorPolicy;
76 class G1Policy;
77 class G1HotCardCache;
78 class G1RemSet;
79 class G1YoungRemSetSamplingThread;
80 class HeapRegionRemSetIterator;
81 class G1ConcurrentMark;
82 class G1ConcurrentMarkThread;
83 class G1ConcurrentRefine;
84 class GenerationCounters;
85 class STWGCTimer;
86 class G1NewTracer;
87 class EvacuationFailedInfo;
88 class nmethod;
89 class WorkGang;
90 class G1Allocator;
91 class G1ArchiveAllocator;
92 class G1FullGCScope;
93 class G1HeapVerifier;
94 class G1HeapSizingPolicy;
95 class G1HeapSummary;
96 class G1EvacSummary;
97
98 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue;
99 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
100
101 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
102 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
103
104 // The G1 STW is alive closure.
105 // An instance is embedded into the G1CH and used as the
106 // (optional) _is_alive_non_header closure in the STW
107 // reference processor. It is also extensively used during
108 // reference processing during STW evacuation pauses.
109 class G1STWIsAliveClosure : public BoolObjectClosure {
110 G1CollectedHeap* _g1h;
111 public:
112 G1STWIsAliveClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
113 bool do_object_b(oop p);
114 };
115
116 class G1STWSubjectToDiscoveryClosure : public BoolObjectClosure {
117 G1CollectedHeap* _g1h;
118 public:
119 G1STWSubjectToDiscoveryClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
120 bool do_object_b(oop p);
121 };
122
123 class G1RegionMappingChangedListener : public G1MappingChangedListener {
124 private:
125 void reset_from_card_cache(uint start_idx, size_t num_regions);
126 public:
127 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
128 };
129
130 class G1CollectedHeap : public CollectedHeap {
131 friend class G1FreeCollectionSetTask;
132 friend class VM_CollectForMetadataAllocation;
133 friend class VM_G1CollectForAllocation;
134 friend class VM_G1CollectFull;
135 friend class VMStructs;
136 friend class MutatorAllocRegion;
137 friend class G1FullCollector;
138 friend class G1GCAllocRegion;
139 friend class G1HeapVerifier;
140
141 // Closures used in implementation.
142 friend class G1ParScanThreadState;
143 friend class G1ParScanThreadStateSet;
144 friend class G1ParTask;
145 friend class G1PLABAllocator;
146 friend class G1PrepareCompactClosure;
147
148 // Other related classes.
149 friend class HeapRegionClaimer;
150
151 // Testing classes.
152 friend class G1CheckCSetFastTableClosure;
153
154 private:
155 G1YoungRemSetSamplingThread* _young_gen_sampling_thread;
156
157 WorkGang* _workers;
158 G1CollectorPolicy* _collector_policy;
159 G1CardTable* _card_table;
160
161 SoftRefPolicy _soft_ref_policy;
162
163 GCMemoryManager _memory_manager;
164 GCMemoryManager _full_gc_memory_manager;
165
166 MemoryPool* _eden_pool;
167 MemoryPool* _survivor_pool;
168 MemoryPool* _old_pool;
169
170 static size_t _humongous_object_threshold_in_words;
171
172 // It keeps track of the old regions.
173 HeapRegionSet _old_set;
174
175 // It keeps track of the humongous regions.
176 HeapRegionSet _humongous_set;
177
178 virtual void initialize_serviceability();
179
180 void eagerly_reclaim_humongous_regions();
181 // Start a new incremental collection set for the next pause.
182 void start_new_collection_set();
183
184 // The number of regions we could create by expansion.
185 uint _expansion_regions;
186
187 // The block offset table for the G1 heap.
188 G1BlockOffsetTable* _bot;
189
190 // Tears down the region sets / lists so that they are empty and the
191 // regions on the heap do not belong to a region set / list. The
192 // only exception is the humongous set which we leave unaltered. If
193 // free_list_only is true, it will only tear down the master free
194 // list. It is called before a Full GC (free_list_only == false) or
195 // before heap shrinking (free_list_only == true).
196 void tear_down_region_sets(bool free_list_only);
197
198 // Rebuilds the region sets / lists so that they are repopulated to
199 // reflect the contents of the heap. The only exception is the
200 // humongous set which was not torn down in the first place. If
201 // free_list_only is true, it will only rebuild the master free
202 // list. It is called after a Full GC (free_list_only == false) or
203 // after heap shrinking (free_list_only == true).
204 void rebuild_region_sets(bool free_list_only);
205
206 // Callback for region mapping changed events.
207 G1RegionMappingChangedListener _listener;
208
209 // The sequence of all heap regions in the heap.
210 HeapRegionManager _hrm;
211
212 // Manages all allocations with regions except humongous object allocations.
213 G1Allocator* _allocator;
214
215 // Manages all heap verification.
216 G1HeapVerifier* _verifier;
217
218 // Outside of GC pauses, the number of bytes used in all regions other
219 // than the current allocation region(s).
220 size_t _summary_bytes_used;
221
222 void increase_used(size_t bytes);
223 void decrease_used(size_t bytes);
224
225 void set_used(size_t bytes);
226
227 // Class that handles archive allocation ranges.
228 G1ArchiveAllocator* _archive_allocator;
229
230 // GC allocation statistics policy for survivors.
231 G1EvacStats _survivor_evac_stats;
232
233 // GC allocation statistics policy for tenured objects.
234 G1EvacStats _old_evac_stats;
235
236 // It specifies whether we should attempt to expand the heap after a
237 // region allocation failure. If heap expansion fails we set this to
238 // false so that we don't re-attempt the heap expansion (it's likely
239 // that subsequent expansion attempts will also fail if one fails).
240 // Currently, it is only consulted during GC and it's reset at the
241 // start of each GC.
242 bool _expand_heap_after_alloc_failure;
243
244 // Helper for monitoring and management support.
245 G1MonitoringSupport* _g1mm;
246
247 // Records whether the region at the given index is (still) a
248 // candidate for eager reclaim. Only valid for humongous start
249 // regions; other regions have unspecified values. Humongous start
250 // regions are initialized at start of collection pause, with
251 // candidates removed from the set as they are found reachable from
252 // roots or the young generation.
253 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> {
254 protected:
255 bool default_value() const { return false; }
256 public:
257 void clear() { G1BiasedMappedArray<bool>::clear(); }
258 void set_candidate(uint region, bool value) {
259 set_by_index(region, value);
260 }
261 bool is_candidate(uint region) {
262 return get_by_index(region);
263 }
264 };
265
266 HumongousReclaimCandidates _humongous_reclaim_candidates;
267 // Stores whether during humongous object registration we found candidate regions.
268 // If not, we can skip a few steps.
269 bool _has_humongous_reclaim_candidates;
270
271 G1HRPrinter _hr_printer;
272
273 // It decides whether an explicit GC should start a concurrent cycle
274 // instead of doing a STW GC. Currently, a concurrent cycle is
275 // explicitly started if:
276 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
277 // (b) cause == _g1_humongous_allocation
278 // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
279 // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent.
280 // (e) cause == _wb_conc_mark
281 bool should_do_concurrent_full_gc(GCCause::Cause cause);
282
283 // indicates whether we are in young or mixed GC mode
284 G1CollectorState _collector_state;
285
286 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
287 // concurrent cycles) we have started.
288 volatile uint _old_marking_cycles_started;
289
290 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
291 // concurrent cycles) we have completed.
292 volatile uint _old_marking_cycles_completed;
293
294 // This is a non-product method that is helpful for testing. It is
295 // called at the end of a GC and artificially expands the heap by
296 // allocating a number of dead regions. This way we can induce very
297 // frequent marking cycles and stress the cleanup / concurrent
298 // cleanup code more (as all the regions that will be allocated by
299 // this method will be found dead by the marking cycle).
300 void allocate_dummy_regions() PRODUCT_RETURN;
301
302 // If the HR printer is active, dump the state of the regions in the
303 // heap after a compaction.
304 void print_hrm_post_compaction();
305
306 // Create a memory mapper for auxiliary data structures of the given size and
307 // translation factor.
308 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description,
309 size_t size,
310 size_t translation_factor);
311
312 void trace_heap(GCWhen::Type when, const GCTracer* tracer);
313
314 // These are macros so that, if the assert fires, we get the correct
315 // line number, file, etc.
316
317 #define heap_locking_asserts_params(_extra_message_) \
318 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
319 (_extra_message_), \
320 BOOL_TO_STR(Heap_lock->owned_by_self()), \
321 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
322 BOOL_TO_STR(Thread::current()->is_VM_thread())
323
324 #define assert_heap_locked() \
325 do { \
326 assert(Heap_lock->owned_by_self(), \
327 heap_locking_asserts_params("should be holding the Heap_lock")); \
328 } while (0)
329
330 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
331 do { \
332 assert(Heap_lock->owned_by_self() || \
333 (SafepointSynchronize::is_at_safepoint() && \
334 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
335 heap_locking_asserts_params("should be holding the Heap_lock or " \
336 "should be at a safepoint")); \
337 } while (0)
338
339 #define assert_heap_locked_and_not_at_safepoint() \
340 do { \
341 assert(Heap_lock->owned_by_self() && \
342 !SafepointSynchronize::is_at_safepoint(), \
343 heap_locking_asserts_params("should be holding the Heap_lock and " \
344 "should not be at a safepoint")); \
345 } while (0)
346
347 #define assert_heap_not_locked() \
348 do { \
349 assert(!Heap_lock->owned_by_self(), \
350 heap_locking_asserts_params("should not be holding the Heap_lock")); \
351 } while (0)
352
353 #define assert_heap_not_locked_and_not_at_safepoint() \
354 do { \
355 assert(!Heap_lock->owned_by_self() && \
356 !SafepointSynchronize::is_at_safepoint(), \
357 heap_locking_asserts_params("should not be holding the Heap_lock and " \
358 "should not be at a safepoint")); \
359 } while (0)
360
361 #define assert_at_safepoint_on_vm_thread() \
362 do { \
363 assert_at_safepoint(); \
364 assert(Thread::current_or_null() != NULL, "no current thread"); \
365 assert(Thread::current()->is_VM_thread(), "current thread is not VM thread"); \
366 } while (0)
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* _g1_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. If the region is to be used as an old region or for a
386 // humongous object, set is_old to true. If not, to false.
387 HeapRegion* new_region(size_t word_size, bool is_old, 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(InCSetState dest);
468 HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest);
469 void retire_gc_alloc_region(HeapRegion* alloc_region,
470 size_t allocated_bytes, InCSetState 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 // Resize the heap if necessary after a full collection.
485 void resize_if_necessary_after_full_collection();
486
487 // Callback from VM_G1CollectForAllocation operation.
488 // This function does everything necessary/possible to satisfy a
489 // failed allocation request (including collection, expansion, etc.)
490 HeapWord* satisfy_failed_allocation(size_t word_size,
491 bool* succeeded);
492 // Internal helpers used during full GC to split it up to
493 // increase readability.
494 void abort_concurrent_cycle();
495 void verify_before_full_collection(bool explicit_gc);
496 void prepare_heap_for_full_collection();
497 void prepare_heap_for_mutators();
498 void abort_refinement();
499 void verify_after_full_collection();
500 void print_heap_after_full_collection(G1HeapTransition* heap_transition);
501
502 // Helper method for satisfy_failed_allocation()
503 HeapWord* satisfy_failed_allocation_helper(size_t word_size,
504 bool do_gc,
505 bool clear_all_soft_refs,
506 bool expect_null_mutator_alloc_region,
507 bool* gc_succeeded);
508
509 // Attempting to expand the heap sufficiently
510 // to support an allocation of the given "word_size". If
511 // successful, perform the allocation and return the address of the
512 // allocated block, or else "NULL".
513 HeapWord* expand_and_allocate(size_t word_size);
514
515 // Process any reference objects discovered.
516 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states);
517
518 // If during an initial mark pause we may install a pending list head which is not
519 // otherwise reachable ensure that it is marked in the bitmap for concurrent marking
520 // to discover.
521 void make_pending_list_reachable();
522
523 // Merges the information gathered on a per-thread basis for all worker threads
524 // during GC into global variables.
525 void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states);
526 public:
527 G1YoungRemSetSamplingThread* sampling_thread() const { return _young_gen_sampling_thread; }
528
529 WorkGang* workers() const { return _workers; }
530
531 G1Allocator* allocator() {
532 return _allocator;
533 }
534
535 G1HeapVerifier* verifier() {
536 return _verifier;
537 }
538
539 G1MonitoringSupport* g1mm() {
540 assert(_g1mm != NULL, "should have been initialized");
541 return _g1mm;
542 }
543
544 // Expand the garbage-first heap by at least the given size (in bytes!).
545 // Returns true if the heap was expanded by the requested amount;
546 // false otherwise.
547 // (Rounds up to a HeapRegion boundary.)
548 bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL);
549
550 // Returns the PLAB statistics for a given destination.
551 inline G1EvacStats* alloc_buffer_stats(InCSetState dest);
552
553 // Determines PLAB size for a given destination.
554 inline size_t desired_plab_sz(InCSetState dest);
555
556 // Do anything common to GC's.
557 void gc_prologue(bool full);
558 void gc_epilogue(bool full);
559
560 // Does the given region fulfill remembered set based eager reclaim candidate requirements?
561 bool is_potential_eager_reclaim_candidate(HeapRegion* r) const;
562
563 // Modify the reclaim candidate set and test for presence.
564 // These are only valid for starts_humongous regions.
565 inline void set_humongous_reclaim_candidate(uint region, bool value);
566 inline bool is_humongous_reclaim_candidate(uint region);
567
568 // Remove from the reclaim candidate set. Also remove from the
569 // collection set so that later encounters avoid the slow path.
570 inline void set_humongous_is_live(oop obj);
571
572 // Register the given region to be part of the collection set.
573 inline void register_humongous_region_with_cset(uint index);
574 // Register regions with humongous objects (actually on the start region) in
575 // the in_cset_fast_test table.
576 void register_humongous_regions_with_cset();
577 // We register a region with the fast "in collection set" test. We
578 // simply set to true the array slot corresponding to this region.
579 void register_young_region_with_cset(HeapRegion* r) {
580 _in_cset_fast_test.set_in_young(r->hrm_index());
581 }
582 void register_old_region_with_cset(HeapRegion* r) {
583 _in_cset_fast_test.set_in_old(r->hrm_index());
584 }
585 void clear_in_cset(const HeapRegion* hr) {
586 _in_cset_fast_test.clear(hr);
587 }
588
589 void clear_cset_fast_test() {
590 _in_cset_fast_test.clear();
591 }
592
593 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause);
594
595 // This is called at the start of either a concurrent cycle or a Full
596 // GC to update the number of old marking cycles started.
597 void increment_old_marking_cycles_started();
598
599 // This is called at the end of either a concurrent cycle or a Full
600 // GC to update the number of old marking cycles completed. Those two
601 // can happen in a nested fashion, i.e., we start a concurrent
602 // cycle, a Full GC happens half-way through it which ends first,
603 // and then the cycle notices that a Full GC happened and ends
604 // too. The concurrent parameter is a boolean to help us do a bit
605 // tighter consistency checking in the method. If concurrent is
606 // false, the caller is the inner caller in the nesting (i.e., the
607 // Full GC). If concurrent is true, the caller is the outer caller
608 // in this nesting (i.e., the concurrent cycle). Further nesting is
609 // not currently supported. The end of this call also notifies
610 // the FullGCCount_lock in case a Java thread is waiting for a full
611 // GC to happen (e.g., it called System.gc() with
612 // +ExplicitGCInvokesConcurrent).
613 void increment_old_marking_cycles_completed(bool concurrent);
614
615 uint old_marking_cycles_completed() {
616 return _old_marking_cycles_completed;
617 }
618
619 G1HRPrinter* hr_printer() { return &_hr_printer; }
620
621 // Allocates a new heap region instance.
622 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr);
623
624 // Allocate the highest free region in the reserved heap. This will commit
625 // regions as necessary.
626 HeapRegion* alloc_highest_free_region();
627
628 // Frees a non-humongous region by initializing its contents and
629 // adding it to the free list that's passed as a parameter (this is
630 // usually a local list which will be appended to the master free
631 // list later). The used bytes of freed regions are accumulated in
632 // pre_used. If skip_remset is true, the region's RSet will not be freed
633 // up. If skip_hot_card_cache is true, the region's hot card cache will not
634 // be freed up. The assumption is that this will be done later.
635 // The locked parameter indicates if the caller has already taken
636 // care of proper synchronization. This may allow some optimizations.
637 void free_region(HeapRegion* hr,
638 FreeRegionList* free_list,
639 bool skip_remset,
640 bool skip_hot_card_cache = false,
641 bool locked = false);
642
643 // It dirties the cards that cover the block so that the post
644 // write barrier never queues anything when updating objects on this
645 // block. It is assumed (and in fact we assert) that the block
646 // belongs to a young region.
647 inline void dirty_young_block(HeapWord* start, size_t word_size);
648
649 // Frees a humongous region by collapsing it into individual regions
650 // and calling free_region() for each of them. The freed regions
651 // will be added to the free list that's passed as a parameter (this
652 // is usually a local list which will be appended to the master free
653 // list later).
654 // The method assumes that only a single thread is ever calling
655 // this for a particular region at once.
656 void free_humongous_region(HeapRegion* hr,
657 FreeRegionList* free_list);
658
659 // Facility for allocating in 'archive' regions in high heap memory and
660 // recording the allocated ranges. These should all be called from the
661 // VM thread at safepoints, without the heap lock held. They can be used
662 // to create and archive a set of heap regions which can be mapped at the
663 // same fixed addresses in a subsequent JVM invocation.
664 void begin_archive_alloc_range(bool open = false);
665
666 // Check if the requested size would be too large for an archive allocation.
667 bool is_archive_alloc_too_large(size_t word_size);
668
669 // Allocate memory of the requested size from the archive region. This will
670 // return NULL if the size is too large or if no memory is available. It
671 // does not trigger a garbage collection.
672 HeapWord* archive_mem_allocate(size_t word_size);
673
674 // Optionally aligns the end address and returns the allocated ranges in
675 // an array of MemRegions in order of ascending addresses.
676 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
677 size_t end_alignment_in_bytes = 0);
678
679 // Facility for allocating a fixed range within the heap and marking
680 // the containing regions as 'archive'. For use at JVM init time, when the
681 // caller may mmap archived heap data at the specified range(s).
682 // Verify that the MemRegions specified in the argument array are within the
683 // reserved heap.
684 bool check_archive_addresses(MemRegion* range, size_t count);
685
686 // Commit the appropriate G1 regions containing the specified MemRegions
687 // and mark them as 'archive' regions. The regions in the array must be
688 // non-overlapping and in order of ascending address.
689 bool alloc_archive_regions(MemRegion* range, size_t count, bool open);
690
691 // Insert any required filler objects in the G1 regions around the specified
692 // ranges to make the regions parseable. This must be called after
693 // alloc_archive_regions, and after class loading has occurred.
694 void fill_archive_regions(MemRegion* range, size_t count);
695
696 // For each of the specified MemRegions, uncommit the containing G1 regions
697 // which had been allocated by alloc_archive_regions. This should be called
698 // rather than fill_archive_regions at JVM init time if the archive file
699 // mapping failed, with the same non-overlapping and sorted MemRegion array.
700 void dealloc_archive_regions(MemRegion* range, size_t count);
701
702 private:
703
704 // Shrink the garbage-first heap by at most the given size (in bytes!).
705 // (Rounds down to a HeapRegion boundary.)
706 void shrink(size_t expand_bytes);
707 void shrink_helper(size_t expand_bytes);
708
709 #if TASKQUEUE_STATS
710 static void print_taskqueue_stats_hdr(outputStream* const st);
711 void print_taskqueue_stats() const;
712 void reset_taskqueue_stats();
713 #endif // TASKQUEUE_STATS
714
715 // Schedule the VM operation that will do an evacuation pause to
716 // satisfy an allocation request of word_size. *succeeded will
717 // return whether the VM operation was successful (it did do an
718 // evacuation pause) or not (another thread beat us to it or the GC
719 // locker was active). Given that we should not be holding the
720 // Heap_lock when we enter this method, we will pass the
721 // gc_count_before (i.e., total_collections()) as a parameter since
722 // it has to be read while holding the Heap_lock. Currently, both
723 // methods that call do_collection_pause() release the Heap_lock
724 // before the call, so it's easy to read gc_count_before just before.
725 HeapWord* do_collection_pause(size_t word_size,
726 uint gc_count_before,
727 bool* succeeded,
728 GCCause::Cause gc_cause);
729
730 void wait_for_root_region_scanning();
731
732 // The guts of the incremental collection pause, executed by the vm
733 // thread. It returns false if it is unable to do the collection due
734 // to the GC locker being active, true otherwise
735 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
736
737 // Actually do the work of evacuating the collection set.
738 void evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states);
739
740 void pre_evacuate_collection_set();
741 void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss);
742
743 // Print the header for the per-thread termination statistics.
744 static void print_termination_stats_hdr();
745 // Print actual per-thread termination statistics.
746 void print_termination_stats(uint worker_id,
747 double elapsed_ms,
748 double strong_roots_ms,
749 double term_ms,
750 size_t term_attempts,
751 size_t alloc_buffer_waste,
752 size_t undo_waste) const;
753 // Update object copying statistics.
754 void record_obj_copy_mem_stats();
755
756 // The hot card cache for remembered set insertion optimization.
757 G1HotCardCache* _hot_card_cache;
758
759 // The g1 remembered set of the heap.
760 G1RemSet* _g1_rem_set;
761
762 // A set of cards that cover the objects for which the Rsets should be updated
763 // concurrently after the collection.
764 DirtyCardQueueSet _dirty_card_queue_set;
765
766 // After a collection pause, convert the regions in the collection set into free
767 // regions.
768 void free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words);
769
770 // Abandon the current collection set without recording policy
771 // statistics or updating free lists.
772 void abandon_collection_set(G1CollectionSet* collection_set);
773
774 // The concurrent marker (and the thread it runs in.)
775 G1ConcurrentMark* _cm;
776 G1ConcurrentMarkThread* _cm_thread;
777
778 // The concurrent refiner.
779 G1ConcurrentRefine* _cr;
780
781 // The parallel task queues
782 RefToScanQueueSet *_task_queues;
783
784 // True iff a evacuation has failed in the current collection.
785 bool _evacuation_failed;
786
787 EvacuationFailedInfo* _evacuation_failed_info_array;
788
789 // Failed evacuations cause some logical from-space objects to have
790 // forwarding pointers to themselves. Reset them.
791 void remove_self_forwarding_pointers();
792
793 // Restore the objects in the regions in the collection set after an
794 // evacuation failure.
795 void restore_after_evac_failure();
796
797 PreservedMarksSet _preserved_marks_set;
798
799 // Preserve the mark of "obj", if necessary, in preparation for its mark
800 // word being overwritten with a self-forwarding-pointer.
801 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m);
802
803 #ifndef PRODUCT
804 // Support for forcing evacuation failures. Analogous to
805 // PromotionFailureALot for the other collectors.
806
807 // Records whether G1EvacuationFailureALot should be in effect
808 // for the current GC
809 bool _evacuation_failure_alot_for_current_gc;
810
811 // Used to record the GC number for interval checking when
812 // determining whether G1EvaucationFailureALot is in effect
813 // for the current GC.
814 size_t _evacuation_failure_alot_gc_number;
815
816 // Count of the number of evacuations between failures.
817 volatile size_t _evacuation_failure_alot_count;
818
819 // Set whether G1EvacuationFailureALot should be in effect
820 // for the current GC (based upon the type of GC and which
821 // command line flags are set);
822 inline bool evacuation_failure_alot_for_gc_type(bool for_young_gc,
823 bool during_initial_mark,
824 bool mark_or_rebuild_in_progress);
825
826 inline void set_evacuation_failure_alot_for_current_gc();
827
828 // Return true if it's time to cause an evacuation failure.
829 inline bool evacuation_should_fail();
830
831 // Reset the G1EvacuationFailureALot counters. Should be called at
832 // the end of an evacuation pause in which an evacuation failure occurred.
833 inline void reset_evacuation_should_fail();
834 #endif // !PRODUCT
835
836 // ("Weak") Reference processing support.
837 //
838 // G1 has 2 instances of the reference processor class. One
839 // (_ref_processor_cm) handles reference object discovery
840 // and subsequent processing during concurrent marking cycles.
841 //
842 // The other (_ref_processor_stw) handles reference object
843 // discovery and processing during full GCs and incremental
844 // evacuation pauses.
845 //
846 // During an incremental pause, reference discovery will be
847 // temporarily disabled for _ref_processor_cm and will be
848 // enabled for _ref_processor_stw. At the end of the evacuation
849 // pause references discovered by _ref_processor_stw will be
850 // processed and discovery will be disabled. The previous
851 // setting for reference object discovery for _ref_processor_cm
852 // will be re-instated.
853 //
854 // At the start of marking:
855 // * Discovery by the CM ref processor is verified to be inactive
856 // and it's discovered lists are empty.
857 // * Discovery by the CM ref processor is then enabled.
858 //
859 // At the end of marking:
860 // * Any references on the CM ref processor's discovered
861 // lists are processed (possibly MT).
862 //
863 // At the start of full GC we:
864 // * Disable discovery by the CM ref processor and
865 // empty CM ref processor's discovered lists
866 // (without processing any entries).
867 // * Verify that the STW ref processor is inactive and it's
868 // discovered lists are empty.
869 // * Temporarily set STW ref processor discovery as single threaded.
870 // * Temporarily clear the STW ref processor's _is_alive_non_header
871 // field.
872 // * Finally enable discovery by the STW ref processor.
873 //
874 // The STW ref processor is used to record any discovered
875 // references during the full GC.
876 //
877 // At the end of a full GC we:
878 // * Enqueue any reference objects discovered by the STW ref processor
879 // that have non-live referents. This has the side-effect of
880 // making the STW ref processor inactive by disabling discovery.
881 // * Verify that the CM ref processor is still inactive
882 // and no references have been placed on it's discovered
883 // lists (also checked as a precondition during initial marking).
884
885 // The (stw) reference processor...
886 ReferenceProcessor* _ref_processor_stw;
887
888 // During reference object discovery, the _is_alive_non_header
889 // closure (if non-null) is applied to the referent object to
890 // determine whether the referent is live. If so then the
891 // reference object does not need to be 'discovered' and can
892 // be treated as a regular oop. This has the benefit of reducing
893 // the number of 'discovered' reference objects that need to
894 // be processed.
895 //
896 // Instance of the is_alive closure for embedding into the
897 // STW reference processor as the _is_alive_non_header field.
898 // Supplying a value for the _is_alive_non_header field is
899 // optional but doing so prevents unnecessary additions to
900 // the discovered lists during reference discovery.
901 G1STWIsAliveClosure _is_alive_closure_stw;
902
903 G1STWSubjectToDiscoveryClosure _is_subject_to_discovery_stw;
904
905 // The (concurrent marking) reference processor...
906 ReferenceProcessor* _ref_processor_cm;
907
908 // Instance of the concurrent mark is_alive closure for embedding
909 // into the Concurrent Marking reference processor as the
910 // _is_alive_non_header field. Supplying a value for the
911 // _is_alive_non_header field is optional but doing so prevents
912 // unnecessary additions to the discovered lists during reference
913 // discovery.
914 G1CMIsAliveClosure _is_alive_closure_cm;
915
916 G1CMSubjectToDiscoveryClosure _is_subject_to_discovery_cm;
917 public:
918
919 RefToScanQueue *task_queue(uint i) const;
920
921 uint num_task_queues() const;
922
923 // A set of cards where updates happened during the GC
924 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
925
926 // Create a G1CollectedHeap with the specified policy.
927 // Must call the initialize method afterwards.
928 // May not return if something goes wrong.
929 G1CollectedHeap(G1CollectorPolicy* policy);
930
931 private:
932 jint initialize_concurrent_refinement();
933 jint initialize_young_gen_sampling_thread();
934 public:
935 // Initialize the G1CollectedHeap to have the initial and
936 // maximum sizes and remembered and barrier sets
937 // specified by the policy object.
938 jint initialize();
939
940 virtual void stop();
941 virtual void safepoint_synchronize_begin();
942 virtual void safepoint_synchronize_end();
943
944 // Return the (conservative) maximum heap alignment for any G1 heap
945 static size_t conservative_max_heap_alignment();
946
947 // Does operations required after initialization has been done.
948 void post_initialize();
949
950 // Initialize weak reference processing.
951 void ref_processing_init();
952
953 virtual Name kind() const {
954 return CollectedHeap::G1;
955 }
956
957 virtual const char* name() const {
958 return "G1";
959 }
960
961 const G1CollectorState* collector_state() const { return &_collector_state; }
962 G1CollectorState* collector_state() { return &_collector_state; }
963
964 // The current policy object for the collector.
965 G1Policy* g1_policy() const { return _g1_policy; }
966
967 const G1CollectionSet* collection_set() const { return &_collection_set; }
968 G1CollectionSet* collection_set() { return &_collection_set; }
969
970 virtual CollectorPolicy* collector_policy() const;
971
972 virtual SoftRefPolicy* soft_ref_policy();
973
974 virtual GrowableArray<GCMemoryManager*> memory_managers();
975 virtual GrowableArray<MemoryPool*> memory_pools();
976
977 // The rem set and barrier set.
978 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
979
980 // Try to minimize the remembered set.
981 void scrub_rem_set();
982
983 // Apply the given closure on all cards in the Hot Card Cache, emptying it.
984 void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i);
985
986 // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it.
987 void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i);
988
989 // The shared block offset table array.
990 G1BlockOffsetTable* bot() const { return _bot; }
991
992 // Reference Processing accessors
993
994 // The STW reference processor....
995 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
996
997 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; }
998
999 // The Concurrent Marking reference processor...
1000 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1001
1002 size_t unused_committed_regions_in_bytes() const;
1003 virtual size_t capacity() const;
1004 virtual size_t used() const;
1005 // This should be called when we're not holding the heap lock. The
1006 // result might be a bit inaccurate.
1007 size_t used_unlocked() const;
1008 size_t recalculate_used() const;
1009
1010 // These virtual functions do the actual allocation.
1011 // Some heaps may offer a contiguous region for shared non-blocking
1012 // allocation, via inlined code (by exporting the address of the top and
1013 // end fields defining the extent of the contiguous allocation region.)
1014 // But G1CollectedHeap doesn't yet support this.
1015
1016 virtual bool is_maximal_no_gc() const {
1017 return _hrm.available() == 0;
1018 }
1019
1020 // Returns whether there are any regions left in the heap for allocation.
1021 bool has_regions_left_for_allocation() const {
1022 return !is_maximal_no_gc() || num_free_regions() != 0;
1023 }
1024
1025 // The current number of regions in the heap.
1026 uint num_regions() const { return _hrm.length(); }
1027
1028 // The max number of regions in the heap.
1029 uint max_regions() const { return _hrm.max_length(); }
1030
1031 // The number of regions that are completely free.
1032 uint num_free_regions() const { return _hrm.num_free_regions(); }
1033
1034 MemoryUsage get_auxiliary_data_memory_usage() const {
1035 return _hrm.get_auxiliary_data_memory_usage();
1036 }
1037
1038 // The number of regions that are not completely free.
1039 uint num_used_regions() const { return num_regions() - num_free_regions(); }
1040
1041 #ifdef ASSERT
1042 bool is_on_master_free_list(HeapRegion* hr) {
1043 return _hrm.is_free(hr);
1044 }
1045 #endif // ASSERT
1046
1047 inline void old_set_add(HeapRegion* hr);
1048 inline void old_set_remove(HeapRegion* hr);
1049
1050 size_t non_young_capacity_bytes() {
1051 return (_old_set.length() + _humongous_set.length()) * HeapRegion::GrainBytes;
1052 }
1053
1054 // Determine whether the given region is one that we are using as an
1055 // old GC alloc region.
1056 bool is_old_gc_alloc_region(HeapRegion* hr);
1057
1058 // Perform a collection of the heap; intended for use in implementing
1059 // "System.gc". This probably implies as full a collection as the
1060 // "CollectedHeap" supports.
1061 virtual void collect(GCCause::Cause cause);
1062
1063 // True iff an evacuation has failed in the most-recent collection.
1064 bool evacuation_failed() { return _evacuation_failed; }
1065
1066 void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed);
1067 void prepend_to_freelist(FreeRegionList* list);
1068 void decrement_summary_bytes(size_t bytes);
1069
1070 virtual bool is_in(const void* p) const;
1071 #ifdef ASSERT
1072 // Returns whether p is in one of the available areas of the heap. Slow but
1073 // extensive version.
1074 bool is_in_exact(const void* p) const;
1075 #endif
1076
1077 // Return "TRUE" iff the given object address is within the collection
1078 // set. Assumes that the reference points into the heap.
1079 inline bool is_in_cset(const HeapRegion *hr);
1080 inline bool is_in_cset(oop obj);
1081 inline bool is_in_cset(HeapWord* addr);
1082
1083 inline bool is_in_cset_or_humongous(const oop obj);
1084
1085 private:
1086 // This array is used for a quick test on whether a reference points into
1087 // the collection set or not. Each of the array's elements denotes whether the
1088 // corresponding region is in the collection set or not.
1089 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test;
1090
1091 public:
1092
1093 inline InCSetState in_cset_state(const oop obj);
1094
1095 // Return "TRUE" iff the given object address is in the reserved
1096 // region of g1.
1097 bool is_in_g1_reserved(const void* p) const {
1098 return _hrm.reserved().contains(p);
1099 }
1100
1101 // Returns a MemRegion that corresponds to the space that has been
1102 // reserved for the heap
1103 MemRegion g1_reserved() const {
1104 return _hrm.reserved();
1105 }
1106
1107 virtual bool is_in_closed_subset(const void* p) const;
1108
1109 G1HotCardCache* g1_hot_card_cache() const { return _hot_card_cache; }
1110
1111 G1CardTable* card_table() const {
1112 return _card_table;
1113 }
1114
1115 // Iteration functions.
1116
1117 // Iterate over all objects, calling "cl.do_object" on each.
1118 virtual void object_iterate(ObjectClosure* cl);
1119
1120 virtual void safe_object_iterate(ObjectClosure* cl) {
1121 object_iterate(cl);
1122 }
1123
1124 // Iterate over heap regions, in address order, terminating the
1125 // iteration early if the "do_heap_region" method returns "true".
1126 void heap_region_iterate(HeapRegionClosure* blk) const;
1127
1128 // Return the region with the given index. It assumes the index is valid.
1129 inline HeapRegion* region_at(uint index) const;
1130
1131 // Return the next region (by index) that is part of the same
1132 // humongous object that hr is part of.
1133 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const;
1134
1135 // Calculate the region index of the given address. Given address must be
1136 // within the heap.
1137 inline uint addr_to_region(HeapWord* addr) const;
1138
1139 inline HeapWord* bottom_addr_for_region(uint index) const;
1140
1141 // Two functions to iterate over the heap regions in parallel. Threads
1142 // compete using the HeapRegionClaimer to claim the regions before
1143 // applying the closure on them.
1144 // The _from_worker_offset version uses the HeapRegionClaimer and
1145 // the worker id to calculate a start offset to prevent all workers to
1146 // start from the point.
1147 void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
1148 HeapRegionClaimer* hrclaimer,
1149 uint worker_id) const;
1150
1151 void heap_region_par_iterate_from_start(HeapRegionClosure* cl,
1152 HeapRegionClaimer* hrclaimer) const;
1153
1154 // Iterate over the regions (if any) in the current collection set.
1155 void collection_set_iterate(HeapRegionClosure* blk);
1156
1157 // Iterate over the regions (if any) in the current collection set. Starts the
1158 // iteration over the entire collection set so that the start regions of a given
1159 // worker id over the set active_workers are evenly spread across the set of
1160 // collection set regions.
1161 void collection_set_iterate_from(HeapRegionClosure *blk, uint worker_id);
1162
1163 // Returns the HeapRegion that contains addr. addr must not be NULL.
1164 template <class T>
1165 inline HeapRegion* heap_region_containing(const T addr) const;
1166
1167 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1168 // each address in the (reserved) heap is a member of exactly
1169 // one block. The defining characteristic of a block is that it is
1170 // possible to find its size, and thus to progress forward to the next
1171 // block. (Blocks may be of different sizes.) Thus, blocks may
1172 // represent Java objects, or they might be free blocks in a
1173 // free-list-based heap (or subheap), as long as the two kinds are
1174 // distinguishable and the size of each is determinable.
1175
1176 // Returns the address of the start of the "block" that contains the
1177 // address "addr". We say "blocks" instead of "object" since some heaps
1178 // may not pack objects densely; a chunk may either be an object or a
1179 // non-object.
1180 virtual HeapWord* block_start(const void* addr) const;
1181
1182 // Requires "addr" to be the start of a chunk, and returns its size.
1183 // "addr + size" is required to be the start of a new chunk, or the end
1184 // of the active area of the heap.
1185 virtual size_t block_size(const HeapWord* addr) const;
1186
1187 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1188 // the block is an object.
1189 virtual bool block_is_obj(const HeapWord* addr) const;
1190
1191 // Section on thread-local allocation buffers (TLABs)
1192 // See CollectedHeap for semantics.
1193
1194 bool supports_tlab_allocation() const;
1195 size_t tlab_capacity(Thread* ignored) const;
1196 size_t tlab_used(Thread* ignored) const;
1197 size_t max_tlab_size() const;
1198 size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1199
1200 inline bool is_in_young(const oop obj);
1201
1202 // Returns "true" iff the given word_size is "very large".
1203 static bool is_humongous(size_t word_size) {
1204 // Note this has to be strictly greater-than as the TLABs
1205 // are capped at the humongous threshold and we want to
1206 // ensure that we don't try to allocate a TLAB as
1207 // humongous and that we don't allocate a humongous
1208 // object in a TLAB.
1209 return word_size > _humongous_object_threshold_in_words;
1210 }
1211
1212 // Returns the humongous threshold for a specific region size
1213 static size_t humongous_threshold_for(size_t region_size) {
1214 return (region_size / 2);
1215 }
1216
1217 // Returns the number of regions the humongous object of the given word size
1218 // requires.
1219 static size_t humongous_obj_size_in_regions(size_t word_size);
1220
1221 // Print the maximum heap capacity.
1222 virtual size_t max_capacity() const;
1223
1224 virtual jlong millis_since_last_gc();
1225
1226
1227 // Convenience function to be used in situations where the heap type can be
1228 // asserted to be this type.
1229 static G1CollectedHeap* heap();
1230
1231 void set_region_short_lived_locked(HeapRegion* hr);
1232 // add appropriate methods for any other surv rate groups
1233
1234 const G1SurvivorRegions* survivor() const { return &_survivor; }
1235
1236 uint survivor_regions_count() const {
1237 return _survivor.length();
1238 }
1239
1240 uint eden_regions_count() const {
1241 return _eden.length();
1242 }
1243
1244 uint young_regions_count() const {
1245 return _eden.length() + _survivor.length();
1246 }
1247
1248 uint old_regions_count() const { return _old_set.length(); }
1249
1250 uint humongous_regions_count() const { return _humongous_set.length(); }
1251
1252 #ifdef ASSERT
1253 bool check_young_list_empty();
1254 #endif
1255
1256 // *** Stuff related to concurrent marking. It's not clear to me that so
1257 // many of these need to be public.
1258
1259 // The functions below are helper functions that a subclass of
1260 // "CollectedHeap" can use in the implementation of its virtual
1261 // functions.
1262 // This performs a concurrent marking of the live objects in a
1263 // bitmap off to the side.
1264 void do_concurrent_mark();
1265
1266 bool is_marked_next(oop obj) const;
1267
1268 // Determine if an object is dead, given the object and also
1269 // the region to which the object belongs. An object is dead
1270 // iff a) it was not allocated since the last mark, b) it
1271 // is not marked, and c) it is not in an archive region.
1272 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1273 return
1274 hr->is_obj_dead(obj, _cm->prev_mark_bitmap()) &&
1275 !hr->is_archive();
1276 }
1277
1278 // This function returns true when an object has been
1279 // around since the previous marking and hasn't yet
1280 // been marked during this marking, and is not in an archive region.
1281 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1282 return
1283 !hr->obj_allocated_since_next_marking(obj) &&
1284 !is_marked_next(obj) &&
1285 !hr->is_archive();
1286 }
1287
1288 // Determine if an object is dead, given only the object itself.
1289 // This will find the region to which the object belongs and
1290 // then call the region version of the same function.
1291
1292 // Added if it is NULL it isn't dead.
1293
1294 inline bool is_obj_dead(const oop obj) const;
1295
1296 inline bool is_obj_ill(const oop obj) const;
1297
1298 inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const;
1299 inline bool is_obj_dead_full(const oop obj) const;
1300
1301 G1ConcurrentMark* concurrent_mark() const { return _cm; }
1302
1303 // Refinement
1304
1305 G1ConcurrentRefine* concurrent_refine() const { return _cr; }
1306
1307 // Optimized nmethod scanning support routines
1308
1309 // Is an oop scavengeable
1310 virtual bool is_scavengable(oop obj);
1311
1312 // Register the given nmethod with the G1 heap.
1313 virtual void register_nmethod(nmethod* nm);
1314
1315 // Unregister the given nmethod from the G1 heap.
1316 virtual void unregister_nmethod(nmethod* nm);
1317
1318 // Free up superfluous code root memory.
1319 void purge_code_root_memory();
1320
1321 // Rebuild the strong code root lists for each region
1322 // after a full GC.
1323 void rebuild_strong_code_roots();
1324
1325 // Partial cleaning used when class unloading is disabled.
1326 // Let the caller choose what structures to clean out:
1327 // - StringTable
1328 // - SymbolTable
1329 // - StringDeduplication structures
1330 void partial_cleaning(BoolObjectClosure* is_alive, bool unlink_strings, bool unlink_symbols, bool unlink_string_dedup);
1331
1332 // Complete cleaning used when class unloading is enabled.
1333 // Cleans out all structures handled by partial_cleaning and also the CodeCache.
1334 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred);
1335
1336 // Redirty logged cards in the refinement queue.
1337 void redirty_logged_cards();
1338 // Verification
1339
1340 // Deduplicate the string
1341 virtual void deduplicate_string(oop str);
1342
1343 // Perform any cleanup actions necessary before allowing a verification.
1344 virtual void prepare_for_verify();
1345
1346 // Perform verification.
1347
1348 // vo == UsePrevMarking -> use "prev" marking information,
1349 // vo == UseNextMarking -> use "next" marking information
1350 // vo == UseFullMarking -> use "next" marking bitmap but no TAMS
1351 //
1352 // NOTE: Only the "prev" marking information is guaranteed to be
1353 // consistent most of the time, so most calls to this should use
1354 // vo == UsePrevMarking.
1355 // Currently, there is only one case where this is called with
1356 // vo == UseNextMarking, which is to verify the "next" marking
1357 // information at the end of remark.
1358 // Currently there is only one place where this is called with
1359 // vo == UseFullMarking, which is to verify the marking during a
1360 // full GC.
1361 void verify(VerifyOption vo);
1362
1363 // WhiteBox testing support.
1364 virtual bool supports_concurrent_phase_control() const;
1365 virtual const char* const* concurrent_phases() const;
1366 virtual bool request_concurrent_phase(const char* phase);
1367
1368 virtual WorkGang* get_safepoint_workers() { return _workers; }
1369
1370 // The methods below are here for convenience and dispatch the
1371 // appropriate method depending on value of the given VerifyOption
1372 // parameter. The values for that parameter, and their meanings,
1373 // are the same as those above.
1374
1375 bool is_obj_dead_cond(const oop obj,
1376 const HeapRegion* hr,
1377 const VerifyOption vo) const;
1378
1379 bool is_obj_dead_cond(const oop obj,
1380 const VerifyOption vo) const;
1381
1382 G1HeapSummary create_g1_heap_summary();
1383 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats);
1384
1385 // Printing
1386 private:
1387 void print_heap_regions() const;
1388 void print_regions_on(outputStream* st) const;
1389
1390 public:
1391 virtual void print_on(outputStream* st) const;
1392 virtual void print_extended_on(outputStream* st) const;
1393 virtual void print_on_error(outputStream* st) const;
1394
1395 virtual void print_gc_threads_on(outputStream* st) const;
1396 virtual void gc_threads_do(ThreadClosure* tc) const;
1397
1398 // Override
1399 void print_tracing_info() const;
1400
1401 // The following two methods are helpful for debugging RSet issues.
1402 void print_cset_rsets() PRODUCT_RETURN;
1403 void print_all_rsets() PRODUCT_RETURN;
1404
1405 public:
1406 size_t pending_card_num();
1407
1408 private:
1409 size_t _max_heap_capacity;
1410 };
1411
1412 class G1ParEvacuateFollowersClosure : public VoidClosure {
1413 private:
1414 double _start_term;
1415 double _term_time;
1416 size_t _term_attempts;
1417
1418 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
1419 void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
1420 protected:
1421 G1CollectedHeap* _g1h;
1422 G1ParScanThreadState* _par_scan_state;
1423 RefToScanQueueSet* _queues;
1424 ParallelTaskTerminator* _terminator;
1425
1426 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
1427 RefToScanQueueSet* queues() { return _queues; }
1428 ParallelTaskTerminator* terminator() { return _terminator; }
1429
1430 public:
1431 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
1432 G1ParScanThreadState* par_scan_state,
1433 RefToScanQueueSet* queues,
1434 ParallelTaskTerminator* terminator)
1435 : _g1h(g1h), _par_scan_state(par_scan_state),
1436 _queues(queues), _terminator(terminator),
1437 _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
1438
1439 void do_void();
1440
1441 double term_time() const { return _term_time; }
1442 size_t term_attempts() const { return _term_attempts; }
1443
1444 private:
1445 inline bool offer_termination();
1446 };
1447
1448 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP