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, bool is_open);
701
702 oop materialize_archived_object(oop obj);
703
704 private:
705
706 // Shrink the garbage-first heap by at most the given size (in bytes!).
707 // (Rounds down to a HeapRegion boundary.)
708 void shrink(size_t expand_bytes);
709 void shrink_helper(size_t expand_bytes);
710
711 #if TASKQUEUE_STATS
712 static void print_taskqueue_stats_hdr(outputStream* const st);
713 void print_taskqueue_stats() const;
714 void reset_taskqueue_stats();
715 #endif // TASKQUEUE_STATS
716
717 // Schedule the VM operation that will do an evacuation pause to
718 // satisfy an allocation request of word_size. *succeeded will
719 // return whether the VM operation was successful (it did do an
720 // evacuation pause) or not (another thread beat us to it or the GC
721 // locker was active). Given that we should not be holding the
722 // Heap_lock when we enter this method, we will pass the
723 // gc_count_before (i.e., total_collections()) as a parameter since
724 // it has to be read while holding the Heap_lock. Currently, both
725 // methods that call do_collection_pause() release the Heap_lock
726 // before the call, so it's easy to read gc_count_before just before.
727 HeapWord* do_collection_pause(size_t word_size,
728 uint gc_count_before,
729 bool* succeeded,
730 GCCause::Cause gc_cause);
731
732 void wait_for_root_region_scanning();
733
734 // The guts of the incremental collection pause, executed by the vm
735 // thread. It returns false if it is unable to do the collection due
736 // to the GC locker being active, true otherwise
737 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
738
739 // Actually do the work of evacuating the collection set.
740 void evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states);
741
742 void pre_evacuate_collection_set();
743 void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss);
744
745 // Print the header for the per-thread termination statistics.
746 static void print_termination_stats_hdr();
747 // Print actual per-thread termination statistics.
748 void print_termination_stats(uint worker_id,
749 double elapsed_ms,
750 double strong_roots_ms,
751 double term_ms,
752 size_t term_attempts,
753 size_t alloc_buffer_waste,
754 size_t undo_waste) const;
755 // Update object copying statistics.
756 void record_obj_copy_mem_stats();
757
758 // The hot card cache for remembered set insertion optimization.
759 G1HotCardCache* _hot_card_cache;
760
761 // The g1 remembered set of the heap.
762 G1RemSet* _g1_rem_set;
763
764 // A set of cards that cover the objects for which the Rsets should be updated
765 // concurrently after the collection.
766 DirtyCardQueueSet _dirty_card_queue_set;
767
768 // After a collection pause, convert the regions in the collection set into free
769 // regions.
770 void free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words);
771
772 // Abandon the current collection set without recording policy
773 // statistics or updating free lists.
774 void abandon_collection_set(G1CollectionSet* collection_set);
775
776 // The concurrent marker (and the thread it runs in.)
777 G1ConcurrentMark* _cm;
778 G1ConcurrentMarkThread* _cm_thread;
779
780 // The concurrent refiner.
781 G1ConcurrentRefine* _cr;
782
783 // The parallel task queues
784 RefToScanQueueSet *_task_queues;
785
786 // True iff a evacuation has failed in the current collection.
787 bool _evacuation_failed;
788
789 EvacuationFailedInfo* _evacuation_failed_info_array;
790
791 // Failed evacuations cause some logical from-space objects to have
792 // forwarding pointers to themselves. Reset them.
793 void remove_self_forwarding_pointers();
794
795 // Restore the objects in the regions in the collection set after an
796 // evacuation failure.
797 void restore_after_evac_failure();
798
799 PreservedMarksSet _preserved_marks_set;
800
801 // Preserve the mark of "obj", if necessary, in preparation for its mark
802 // word being overwritten with a self-forwarding-pointer.
803 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m);
804
805 #ifndef PRODUCT
806 // Support for forcing evacuation failures. Analogous to
807 // PromotionFailureALot for the other collectors.
808
809 // Records whether G1EvacuationFailureALot should be in effect
810 // for the current GC
811 bool _evacuation_failure_alot_for_current_gc;
812
813 // Used to record the GC number for interval checking when
814 // determining whether G1EvaucationFailureALot is in effect
815 // for the current GC.
816 size_t _evacuation_failure_alot_gc_number;
817
818 // Count of the number of evacuations between failures.
819 volatile size_t _evacuation_failure_alot_count;
820
821 // Set whether G1EvacuationFailureALot should be in effect
822 // for the current GC (based upon the type of GC and which
823 // command line flags are set);
824 inline bool evacuation_failure_alot_for_gc_type(bool for_young_gc,
825 bool during_initial_mark,
826 bool mark_or_rebuild_in_progress);
827
828 inline void set_evacuation_failure_alot_for_current_gc();
829
830 // Return true if it's time to cause an evacuation failure.
831 inline bool evacuation_should_fail();
832
833 // Reset the G1EvacuationFailureALot counters. Should be called at
834 // the end of an evacuation pause in which an evacuation failure occurred.
835 inline void reset_evacuation_should_fail();
836 #endif // !PRODUCT
837
838 // ("Weak") Reference processing support.
839 //
840 // G1 has 2 instances of the reference processor class. One
841 // (_ref_processor_cm) handles reference object discovery
842 // and subsequent processing during concurrent marking cycles.
843 //
844 // The other (_ref_processor_stw) handles reference object
845 // discovery and processing during full GCs and incremental
846 // evacuation pauses.
847 //
848 // During an incremental pause, reference discovery will be
849 // temporarily disabled for _ref_processor_cm and will be
850 // enabled for _ref_processor_stw. At the end of the evacuation
851 // pause references discovered by _ref_processor_stw will be
852 // processed and discovery will be disabled. The previous
853 // setting for reference object discovery for _ref_processor_cm
854 // will be re-instated.
855 //
856 // At the start of marking:
857 // * Discovery by the CM ref processor is verified to be inactive
858 // and it's discovered lists are empty.
859 // * Discovery by the CM ref processor is then enabled.
860 //
861 // At the end of marking:
862 // * Any references on the CM ref processor's discovered
863 // lists are processed (possibly MT).
864 //
865 // At the start of full GC we:
866 // * Disable discovery by the CM ref processor and
867 // empty CM ref processor's discovered lists
868 // (without processing any entries).
869 // * Verify that the STW ref processor is inactive and it's
870 // discovered lists are empty.
871 // * Temporarily set STW ref processor discovery as single threaded.
872 // * Temporarily clear the STW ref processor's _is_alive_non_header
873 // field.
874 // * Finally enable discovery by the STW ref processor.
875 //
876 // The STW ref processor is used to record any discovered
877 // references during the full GC.
878 //
879 // At the end of a full GC we:
880 // * Enqueue any reference objects discovered by the STW ref processor
881 // that have non-live referents. This has the side-effect of
882 // making the STW ref processor inactive by disabling discovery.
883 // * Verify that the CM ref processor is still inactive
884 // and no references have been placed on it's discovered
885 // lists (also checked as a precondition during initial marking).
886
887 // The (stw) reference processor...
888 ReferenceProcessor* _ref_processor_stw;
889
890 // During reference object discovery, the _is_alive_non_header
891 // closure (if non-null) is applied to the referent object to
892 // determine whether the referent is live. If so then the
893 // reference object does not need to be 'discovered' and can
894 // be treated as a regular oop. This has the benefit of reducing
895 // the number of 'discovered' reference objects that need to
896 // be processed.
897 //
898 // Instance of the is_alive closure for embedding into the
899 // STW reference processor as the _is_alive_non_header field.
900 // Supplying a value for the _is_alive_non_header field is
901 // optional but doing so prevents unnecessary additions to
902 // the discovered lists during reference discovery.
903 G1STWIsAliveClosure _is_alive_closure_stw;
904
905 G1STWSubjectToDiscoveryClosure _is_subject_to_discovery_stw;
906
907 // The (concurrent marking) reference processor...
908 ReferenceProcessor* _ref_processor_cm;
909
910 // Instance of the concurrent mark is_alive closure for embedding
911 // into the Concurrent Marking reference processor as the
912 // _is_alive_non_header field. Supplying a value for the
913 // _is_alive_non_header field is optional but doing so prevents
914 // unnecessary additions to the discovered lists during reference
915 // discovery.
916 G1CMIsAliveClosure _is_alive_closure_cm;
917
918 G1CMSubjectToDiscoveryClosure _is_subject_to_discovery_cm;
919 public:
920
921 RefToScanQueue *task_queue(uint i) const;
922
923 uint num_task_queues() const;
924
925 // A set of cards where updates happened during the GC
926 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
927
928 // Create a G1CollectedHeap with the specified policy.
929 // Must call the initialize method afterwards.
930 // May not return if something goes wrong.
931 G1CollectedHeap(G1CollectorPolicy* policy);
932
933 private:
934 jint initialize_concurrent_refinement();
935 jint initialize_young_gen_sampling_thread();
936 public:
937 // Initialize the G1CollectedHeap to have the initial and
938 // maximum sizes and remembered and barrier sets
939 // specified by the policy object.
940 jint initialize();
941
942 virtual void stop();
943 virtual void safepoint_synchronize_begin();
944 virtual void safepoint_synchronize_end();
945
946 // Return the (conservative) maximum heap alignment for any G1 heap
947 static size_t conservative_max_heap_alignment();
948
949 // Does operations required after initialization has been done.
950 void post_initialize();
951
952 // Initialize weak reference processing.
953 void ref_processing_init();
954
955 virtual Name kind() const {
956 return CollectedHeap::G1;
957 }
958
959 virtual const char* name() const {
960 return "G1";
961 }
962
963 const G1CollectorState* collector_state() const { return &_collector_state; }
964 G1CollectorState* collector_state() { return &_collector_state; }
965
966 // The current policy object for the collector.
967 G1Policy* g1_policy() const { return _g1_policy; }
968
969 const G1CollectionSet* collection_set() const { return &_collection_set; }
970 G1CollectionSet* collection_set() { return &_collection_set; }
971
972 virtual CollectorPolicy* collector_policy() const;
973
974 virtual SoftRefPolicy* soft_ref_policy();
975
976 virtual GrowableArray<GCMemoryManager*> memory_managers();
977 virtual GrowableArray<MemoryPool*> memory_pools();
978
979 // The rem set and barrier set.
980 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
981
982 // Try to minimize the remembered set.
983 void scrub_rem_set();
984
985 // Apply the given closure on all cards in the Hot Card Cache, emptying it.
986 void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i);
987
988 // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it.
989 void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i);
990
991 // The shared block offset table array.
992 G1BlockOffsetTable* bot() const { return _bot; }
993
994 // Reference Processing accessors
995
996 // The STW reference processor....
997 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
998
999 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; }
1000
1001 // The Concurrent Marking reference processor...
1002 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1003
1004 size_t unused_committed_regions_in_bytes() const;
1005 virtual size_t capacity() const;
1006 virtual size_t used() const;
1007 // This should be called when we're not holding the heap lock. The
1008 // result might be a bit inaccurate.
1009 size_t used_unlocked() const;
1010 size_t recalculate_used() const;
1011
1012 // These virtual functions do the actual allocation.
1013 // Some heaps may offer a contiguous region for shared non-blocking
1014 // allocation, via inlined code (by exporting the address of the top and
1015 // end fields defining the extent of the contiguous allocation region.)
1016 // But G1CollectedHeap doesn't yet support this.
1017
1018 virtual bool is_maximal_no_gc() const {
1019 return _hrm.available() == 0;
1020 }
1021
1022 // Returns whether there are any regions left in the heap for allocation.
1023 bool has_regions_left_for_allocation() const {
1024 return !is_maximal_no_gc() || num_free_regions() != 0;
1025 }
1026
1027 // The current number of regions in the heap.
1028 uint num_regions() const { return _hrm.length(); }
1029
1030 // The max number of regions in the heap.
1031 uint max_regions() const { return _hrm.max_length(); }
1032
1033 // The number of regions that are completely free.
1034 uint num_free_regions() const { return _hrm.num_free_regions(); }
1035
1036 MemoryUsage get_auxiliary_data_memory_usage() const {
1037 return _hrm.get_auxiliary_data_memory_usage();
1038 }
1039
1040 // The number of regions that are not completely free.
1041 uint num_used_regions() const { return num_regions() - num_free_regions(); }
1042
1043 #ifdef ASSERT
1044 bool is_on_master_free_list(HeapRegion* hr) {
1045 return _hrm.is_free(hr);
1046 }
1047 #endif // ASSERT
1048
1049 inline void old_set_add(HeapRegion* hr);
1050 inline void old_set_remove(HeapRegion* hr);
1051
1052 size_t non_young_capacity_bytes() {
1053 return (_old_set.length() + _humongous_set.length()) * HeapRegion::GrainBytes;
1054 }
1055
1056 // Determine whether the given region is one that we are using as an
1057 // old GC alloc region.
1058 bool is_old_gc_alloc_region(HeapRegion* hr);
1059
1060 // Perform a collection of the heap; intended for use in implementing
1061 // "System.gc". This probably implies as full a collection as the
1062 // "CollectedHeap" supports.
1063 virtual void collect(GCCause::Cause cause);
1064
1065 // True iff an evacuation has failed in the most-recent collection.
1066 bool evacuation_failed() { return _evacuation_failed; }
1067
1068 void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed);
1069 void prepend_to_freelist(FreeRegionList* list);
1070 void decrement_summary_bytes(size_t bytes);
1071
1072 virtual bool is_in(const void* p) const;
1073 #ifdef ASSERT
1074 // Returns whether p is in one of the available areas of the heap. Slow but
1075 // extensive version.
1076 bool is_in_exact(const void* p) const;
1077 #endif
1078
1079 // Return "TRUE" iff the given object address is within the collection
1080 // set. Assumes that the reference points into the heap.
1081 inline bool is_in_cset(const HeapRegion *hr);
1082 inline bool is_in_cset(oop obj);
1083 inline bool is_in_cset(HeapWord* addr);
1084
1085 inline bool is_in_cset_or_humongous(const oop obj);
1086
1087 private:
1088 // This array is used for a quick test on whether a reference points into
1089 // the collection set or not. Each of the array's elements denotes whether the
1090 // corresponding region is in the collection set or not.
1091 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test;
1092
1093 public:
1094
1095 inline InCSetState in_cset_state(const oop obj);
1096
1097 // Return "TRUE" iff the given object address is in the reserved
1098 // region of g1.
1099 bool is_in_g1_reserved(const void* p) const {
1100 return _hrm.reserved().contains(p);
1101 }
1102
1103 // Returns a MemRegion that corresponds to the space that has been
1104 // reserved for the heap
1105 MemRegion g1_reserved() const {
1106 return _hrm.reserved();
1107 }
1108
1109 virtual bool is_in_closed_subset(const void* p) const;
1110
1111 G1HotCardCache* g1_hot_card_cache() const { return _hot_card_cache; }
1112
1113 G1CardTable* card_table() const {
1114 return _card_table;
1115 }
1116
1117 // Iteration functions.
1118
1119 // Iterate over all objects, calling "cl.do_object" on each.
1120 virtual void object_iterate(ObjectClosure* cl);
1121
1122 virtual void safe_object_iterate(ObjectClosure* cl) {
1123 object_iterate(cl);
1124 }
1125
1126 // Iterate over heap regions, in address order, terminating the
1127 // iteration early if the "do_heap_region" method returns "true".
1128 void heap_region_iterate(HeapRegionClosure* blk) const;
1129
1130 // Return the region with the given index. It assumes the index is valid.
1131 inline HeapRegion* region_at(uint index) const;
1132
1133 // Return the next region (by index) that is part of the same
1134 // humongous object that hr is part of.
1135 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const;
1136
1137 // Calculate the region index of the given address. Given address must be
1138 // within the heap.
1139 inline uint addr_to_region(HeapWord* addr) const;
1140
1141 inline HeapWord* bottom_addr_for_region(uint index) const;
1142
1143 // Two functions to iterate over the heap regions in parallel. Threads
1144 // compete using the HeapRegionClaimer to claim the regions before
1145 // applying the closure on them.
1146 // The _from_worker_offset version uses the HeapRegionClaimer and
1147 // the worker id to calculate a start offset to prevent all workers to
1148 // start from the point.
1149 void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
1150 HeapRegionClaimer* hrclaimer,
1151 uint worker_id) const;
1152
1153 void heap_region_par_iterate_from_start(HeapRegionClosure* cl,
1154 HeapRegionClaimer* hrclaimer) const;
1155
1156 // Iterate over the regions (if any) in the current collection set.
1157 void collection_set_iterate(HeapRegionClosure* blk);
1158
1159 // Iterate over the regions (if any) in the current collection set. Starts the
1160 // iteration over the entire collection set so that the start regions of a given
1161 // worker id over the set active_workers are evenly spread across the set of
1162 // collection set regions.
1163 void collection_set_iterate_from(HeapRegionClosure *blk, uint worker_id);
1164
1165 // Returns the HeapRegion that contains addr. addr must not be NULL.
1166 template <class T>
1167 inline HeapRegion* heap_region_containing(const T addr) const;
1168
1169 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1170 // each address in the (reserved) heap is a member of exactly
1171 // one block. The defining characteristic of a block is that it is
1172 // possible to find its size, and thus to progress forward to the next
1173 // block. (Blocks may be of different sizes.) Thus, blocks may
1174 // represent Java objects, or they might be free blocks in a
1175 // free-list-based heap (or subheap), as long as the two kinds are
1176 // distinguishable and the size of each is determinable.
1177
1178 // Returns the address of the start of the "block" that contains the
1179 // address "addr". We say "blocks" instead of "object" since some heaps
1180 // may not pack objects densely; a chunk may either be an object or a
1181 // non-object.
1182 virtual HeapWord* block_start(const void* addr) const;
1183
1184 // Requires "addr" to be the start of a chunk, and returns its size.
1185 // "addr + size" is required to be the start of a new chunk, or the end
1186 // of the active area of the heap.
1187 virtual size_t block_size(const HeapWord* addr) const;
1188
1189 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1190 // the block is an object.
1191 virtual bool block_is_obj(const HeapWord* addr) const;
1192
1193 // Section on thread-local allocation buffers (TLABs)
1194 // See CollectedHeap for semantics.
1195
1196 bool supports_tlab_allocation() const;
1197 size_t tlab_capacity(Thread* ignored) const;
1198 size_t tlab_used(Thread* ignored) const;
1199 size_t max_tlab_size() const;
1200 size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1201
1202 inline bool is_in_young(const oop obj);
1203
1204 // Returns "true" iff the given word_size is "very large".
1205 static bool is_humongous(size_t word_size) {
1206 // Note this has to be strictly greater-than as the TLABs
1207 // are capped at the humongous threshold and we want to
1208 // ensure that we don't try to allocate a TLAB as
1209 // humongous and that we don't allocate a humongous
1210 // object in a TLAB.
1211 return word_size > _humongous_object_threshold_in_words;
1212 }
1213
1214 // Returns the humongous threshold for a specific region size
1215 static size_t humongous_threshold_for(size_t region_size) {
1216 return (region_size / 2);
1217 }
1218
1219 // Returns the number of regions the humongous object of the given word size
1220 // requires.
1221 static size_t humongous_obj_size_in_regions(size_t word_size);
1222
1223 // Print the maximum heap capacity.
1224 virtual size_t max_capacity() const;
1225
1226 virtual jlong millis_since_last_gc();
1227
1228
1229 // Convenience function to be used in situations where the heap type can be
1230 // asserted to be this type.
1231 static G1CollectedHeap* heap();
1232
1233 void set_region_short_lived_locked(HeapRegion* hr);
1234 // add appropriate methods for any other surv rate groups
1235
1236 const G1SurvivorRegions* survivor() const { return &_survivor; }
1237
1238 uint survivor_regions_count() const {
1239 return _survivor.length();
1240 }
1241
1242 uint eden_regions_count() const {
1243 return _eden.length();
1244 }
1245
1246 uint young_regions_count() const {
1247 return _eden.length() + _survivor.length();
1248 }
1249
1250 uint old_regions_count() const { return _old_set.length(); }
1251
1252 uint humongous_regions_count() const { return _humongous_set.length(); }
1253
1254 #ifdef ASSERT
1255 bool check_young_list_empty();
1256 #endif
1257
1258 // *** Stuff related to concurrent marking. It's not clear to me that so
1259 // many of these need to be public.
1260
1261 // The functions below are helper functions that a subclass of
1262 // "CollectedHeap" can use in the implementation of its virtual
1263 // functions.
1264 // This performs a concurrent marking of the live objects in a
1265 // bitmap off to the side.
1266 void do_concurrent_mark();
1267
1268 bool is_marked_next(oop obj) const;
1269
1270 // Determine if an object is dead, given the object and also
1271 // the region to which the object belongs. An object is dead
1272 // iff a) it was not allocated since the last mark, b) it
1273 // is not marked, and c) it is not in an archive region.
1274 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1275 return
1276 hr->is_obj_dead(obj, _cm->prev_mark_bitmap()) &&
1277 !hr->is_archive();
1278 }
1279
1280 // This function returns true when an object has been
1281 // around since the previous marking and hasn't yet
1282 // been marked during this marking, and is not in an archive region.
1283 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1284 return
1285 !hr->obj_allocated_since_next_marking(obj) &&
1286 !is_marked_next(obj) &&
1287 !hr->is_archive();
1288 }
1289
1290 // Determine if an object is dead, given only the object itself.
1291 // This will find the region to which the object belongs and
1292 // then call the region version of the same function.
1293
1294 // Added if it is NULL it isn't dead.
1295
1296 inline bool is_obj_dead(const oop obj) const;
1297
1298 inline bool is_obj_ill(const oop obj) const;
1299
1300 inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const;
1301 inline bool is_obj_dead_full(const oop obj) const;
1302
1303 G1ConcurrentMark* concurrent_mark() const { return _cm; }
1304
1305 // Refinement
1306
1307 G1ConcurrentRefine* concurrent_refine() const { return _cr; }
1308
1309 // Optimized nmethod scanning support routines
1310
1311 // Is an oop scavengeable
1312 virtual bool is_scavengable(oop obj);
1313
1314 // Register the given nmethod with the G1 heap.
1315 virtual void register_nmethod(nmethod* nm);
1316
1317 // Unregister the given nmethod from the G1 heap.
1318 virtual void unregister_nmethod(nmethod* nm);
1319
1320 // Free up superfluous code root memory.
1321 void purge_code_root_memory();
1322
1323 // Rebuild the strong code root lists for each region
1324 // after a full GC.
1325 void rebuild_strong_code_roots();
1326
1327 // Partial cleaning used when class unloading is disabled.
1328 // Let the caller choose what structures to clean out:
1329 // - StringTable
1330 // - SymbolTable
1331 // - StringDeduplication structures
1332 void partial_cleaning(BoolObjectClosure* is_alive, bool unlink_strings, bool unlink_symbols, bool unlink_string_dedup);
1333
1334 // Complete cleaning used when class unloading is enabled.
1335 // Cleans out all structures handled by partial_cleaning and also the CodeCache.
1336 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred);
1337
1338 // Redirty logged cards in the refinement queue.
1339 void redirty_logged_cards();
1340 // Verification
1341
1342 // Deduplicate the string
1343 virtual void deduplicate_string(oop str);
1344
1345 // Perform any cleanup actions necessary before allowing a verification.
1346 virtual void prepare_for_verify();
1347
1348 // Perform verification.
1349
1350 // vo == UsePrevMarking -> use "prev" marking information,
1351 // vo == UseNextMarking -> use "next" marking information
1352 // vo == UseFullMarking -> use "next" marking bitmap but no TAMS
1353 //
1354 // NOTE: Only the "prev" marking information is guaranteed to be
1355 // consistent most of the time, so most calls to this should use
1356 // vo == UsePrevMarking.
1357 // Currently, there is only one case where this is called with
1358 // vo == UseNextMarking, which is to verify the "next" marking
1359 // information at the end of remark.
1360 // Currently there is only one place where this is called with
1361 // vo == UseFullMarking, which is to verify the marking during a
1362 // full GC.
1363 void verify(VerifyOption vo);
1364
1365 // WhiteBox testing support.
1366 virtual bool supports_concurrent_phase_control() const;
1367 virtual const char* const* concurrent_phases() const;
1368 virtual bool request_concurrent_phase(const char* phase);
1369
1370 virtual WorkGang* get_safepoint_workers() { return _workers; }
1371
1372 // The methods below are here for convenience and dispatch the
1373 // appropriate method depending on value of the given VerifyOption
1374 // parameter. The values for that parameter, and their meanings,
1375 // are the same as those above.
1376
1377 bool is_obj_dead_cond(const oop obj,
1378 const HeapRegion* hr,
1379 const VerifyOption vo) const;
1380
1381 bool is_obj_dead_cond(const oop obj,
1382 const VerifyOption vo) const;
1383
1384 G1HeapSummary create_g1_heap_summary();
1385 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats);
1386
1387 // Printing
1388 private:
1389 void print_heap_regions() const;
1390 void print_regions_on(outputStream* st) const;
1391
1392 public:
1393 virtual void print_on(outputStream* st) const;
1394 virtual void print_extended_on(outputStream* st) const;
1395 virtual void print_on_error(outputStream* st) const;
1396
1397 virtual void print_gc_threads_on(outputStream* st) const;
1398 virtual void gc_threads_do(ThreadClosure* tc) const;
1399
1400 // Override
1401 void print_tracing_info() const;
1402
1403 // The following two methods are helpful for debugging RSet issues.
1404 void print_cset_rsets() PRODUCT_RETURN;
1405 void print_all_rsets() PRODUCT_RETURN;
1406
1407 public:
1408 size_t pending_card_num();
1409
1410 private:
1411 size_t _max_heap_capacity;
1412 };
1413
1414 class G1ParEvacuateFollowersClosure : public VoidClosure {
1415 private:
1416 double _start_term;
1417 double _term_time;
1418 size_t _term_attempts;
1419
1420 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
1421 void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
1422 protected:
1423 G1CollectedHeap* _g1h;
1424 G1ParScanThreadState* _par_scan_state;
1425 RefToScanQueueSet* _queues;
1426 ParallelTaskTerminator* _terminator;
1427
1428 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
1429 RefToScanQueueSet* queues() { return _queues; }
1430 ParallelTaskTerminator* terminator() { return _terminator; }
1431
1432 public:
1433 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
1434 G1ParScanThreadState* par_scan_state,
1435 RefToScanQueueSet* queues,
1436 ParallelTaskTerminator* terminator)
1437 : _g1h(g1h), _par_scan_state(par_scan_state),
1438 _queues(queues), _terminator(terminator),
1439 _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
1440
1441 void do_void();
1442
1443 double term_time() const { return _term_time; }
1444 size_t term_attempts() const { return _term_attempts; }
1445
1446 private:
1447 inline bool offer_termination();
1448 };
1449
1450 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP