1 /*
2 * Copyright (c) 2001, 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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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/g1AllocationContext.hpp"
30 #include "gc/g1/g1BiasedArray.hpp"
31 #include "gc/g1/g1CollectionSet.hpp"
32 #include "gc/g1/g1CollectorState.hpp"
33 #include "gc/g1/g1ConcurrentMark.hpp"
34 #include "gc/g1/g1EdenRegions.hpp"
35 #include "gc/g1/g1EvacFailure.hpp"
36 #include "gc/g1/g1EvacStats.hpp"
37 #include "gc/g1/g1HeapTransition.hpp"
38 #include "gc/g1/g1HeapVerifier.hpp"
39 #include "gc/g1/g1HRPrinter.hpp"
40 #include "gc/g1/g1InCSetState.hpp"
41 #include "gc/g1/g1MonitoringSupport.hpp"
42 #include "gc/g1/g1SATBCardTableModRefBS.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 "memory/memRegion.hpp"
53 #include "services/memoryManager.hpp"
54 #include "utilities/stack.hpp"
55
56 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
57 // It uses the "Garbage First" heap organization and algorithm, which
58 // may combine concurrent marking with parallel, incremental compaction of
59 // heap subsets that will yield large amounts of garbage.
60
61 // Forward declarations
62 class HeapRegion;
63 class HRRSCleanupTask;
64 class GenerationSpec;
65 class G1ParScanThreadState;
66 class G1ParScanThreadStateSet;
67 class G1ParScanThreadState;
68 class MemoryPool;
69 class ObjectClosure;
70 class SpaceClosure;
71 class CompactibleSpaceClosure;
72 class Space;
73 class G1CollectionSet;
74 class G1CollectorPolicy;
75 class G1Policy;
76 class G1HotCardCache;
77 class G1RemSet;
78 class G1YoungRemSetSamplingThread;
79 class HeapRegionRemSetIterator;
80 class G1ConcurrentMark;
81 class ConcurrentMarkThread;
82 class G1ConcurrentRefine;
83 class GenerationCounters;
84 class STWGCTimer;
85 class G1NewTracer;
86 class EvacuationFailedInfo;
87 class nmethod;
88 class Ticks;
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* _g1;
111 public:
112 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
113 bool do_object_b(oop p);
114 };
115
116 class G1RegionMappingChangedListener : public G1MappingChangedListener {
117 private:
118 void reset_from_card_cache(uint start_idx, size_t num_regions);
119 public:
120 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
121 };
122
123 class G1CollectedHeap : public CollectedHeap {
124 friend class G1FreeCollectionSetTask;
125 friend class VM_CollectForMetadataAllocation;
126 friend class VM_G1CollectForAllocation;
127 friend class VM_G1CollectFull;
128 friend class VM_G1IncCollectionPause;
129 friend class VMStructs;
130 friend class MutatorAllocRegion;
131 friend class G1FullCollector;
132 friend class G1GCAllocRegion;
133 friend class G1HeapVerifier;
134
135 // Closures used in implementation.
136 friend class G1ParScanThreadState;
137 friend class G1ParScanThreadStateSet;
138 friend class G1ParTask;
139 friend class G1PLABAllocator;
140 friend class G1PrepareCompactClosure;
141
142 // Other related classes.
143 friend class HeapRegionClaimer;
144
145 // Testing classes.
146 friend class G1CheckCSetFastTableClosure;
147
148 private:
149 G1YoungRemSetSamplingThread* _young_gen_sampling_thread;
150
151 WorkGang* _workers;
152 G1CollectorPolicy* _collector_policy;
153
154 GCMemoryManager _memory_manager;
155 GCMemoryManager _full_gc_memory_manager;
156
157 MemoryPool* _eden_pool;
158 MemoryPool* _survivor_pool;
159 MemoryPool* _old_pool;
160
161 static size_t _humongous_object_threshold_in_words;
162
163 // The secondary free list which contains regions that have been
164 // freed up during the cleanup process. This will be appended to
165 // the master free list when appropriate.
166 FreeRegionList _secondary_free_list;
167
168 // It keeps track of the old regions.
169 HeapRegionSet _old_set;
170
171 // It keeps track of the humongous regions.
172 HeapRegionSet _humongous_set;
173
174 virtual void initialize_serviceability();
175
176 void eagerly_reclaim_humongous_regions();
177 // Start a new incremental collection set for the next pause.
178 void start_new_collection_set();
179
180 // The number of regions we could create by expansion.
181 uint _expansion_regions;
182
183 // The block offset table for the G1 heap.
184 G1BlockOffsetTable* _bot;
185
186 // Tears down the region sets / lists so that they are empty and the
187 // regions on the heap do not belong to a region set / list. The
188 // only exception is the humongous set which we leave unaltered. If
189 // free_list_only is true, it will only tear down the master free
190 // list. It is called before a Full GC (free_list_only == false) or
191 // before heap shrinking (free_list_only == true).
192 void tear_down_region_sets(bool free_list_only);
193
194 // Rebuilds the region sets / lists so that they are repopulated to
195 // reflect the contents of the heap. The only exception is the
196 // humongous set which was not torn down in the first place. If
197 // free_list_only is true, it will only rebuild the master free
198 // list. It is called after a Full GC (free_list_only == false) or
199 // after heap shrinking (free_list_only == true).
200 void rebuild_region_sets(bool free_list_only);
201
202 // Callback for region mapping changed events.
203 G1RegionMappingChangedListener _listener;
204
205 // The sequence of all heap regions in the heap.
206 HeapRegionManager _hrm;
207
208 // Manages all allocations with regions except humongous object allocations.
209 G1Allocator* _allocator;
210
211 // Manages all heap verification.
212 G1HeapVerifier* _verifier;
213
214 // Outside of GC pauses, the number of bytes used in all regions other
215 // than the current allocation region(s).
216 size_t _summary_bytes_used;
217
218 void increase_used(size_t bytes);
219 void decrease_used(size_t bytes);
220
221 void set_used(size_t bytes);
222
223 // Class that handles archive allocation ranges.
224 G1ArchiveAllocator* _archive_allocator;
225
226 // Statistics for each allocation context
227 AllocationContextStats _allocation_context_stats;
228
229 // GC allocation statistics policy for survivors.
230 G1EvacStats _survivor_evac_stats;
231
232 // GC allocation statistics policy for tenured objects.
233 G1EvacStats _old_evac_stats;
234
235 // It specifies whether we should attempt to expand the heap after a
236 // region allocation failure. If heap expansion fails we set this to
237 // false so that we don't re-attempt the heap expansion (it's likely
238 // that subsequent expansion attempts will also fail if one fails).
239 // Currently, it is only consulted during GC and it's reset at the
240 // start of each GC.
241 bool _expand_heap_after_alloc_failure;
242
243 // Helper for monitoring and management support.
244 G1MonitoringSupport* _g1mm;
245
246 // Records whether the region at the given index is (still) a
247 // candidate for eager reclaim. Only valid for humongous start
248 // regions; other regions have unspecified values. Humongous start
249 // regions are initialized at start of collection pause, with
250 // candidates removed from the set as they are found reachable from
251 // roots or the young generation.
252 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> {
253 protected:
254 bool default_value() const { return false; }
255 public:
256 void clear() { G1BiasedMappedArray<bool>::clear(); }
257 void set_candidate(uint region, bool value) {
258 set_by_index(region, value);
259 }
260 bool is_candidate(uint region) {
261 return get_by_index(region);
262 }
263 };
264
265 HumongousReclaimCandidates _humongous_reclaim_candidates;
266 // Stores whether during humongous object registration we found candidate regions.
267 // If not, we can skip a few steps.
268 bool _has_humongous_reclaim_candidates;
269
270 volatile uint _gc_time_stamp;
271
272 G1HRPrinter _hr_printer;
273
274 // It decides whether an explicit GC should start a concurrent cycle
275 // instead of doing a STW GC. Currently, a concurrent cycle is
276 // explicitly started if:
277 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
278 // (b) cause == _g1_humongous_allocation
279 // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
280 // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent.
281 // (e) cause == _update_allocation_context_stats_inc
282 // (f) cause == _wb_conc_mark
283 bool should_do_concurrent_full_gc(GCCause::Cause cause);
284
285 // indicates whether we are in young or mixed GC mode
286 G1CollectorState _collector_state;
287
288 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
289 // concurrent cycles) we have started.
290 volatile uint _old_marking_cycles_started;
291
292 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
293 // concurrent cycles) we have completed.
294 volatile uint _old_marking_cycles_completed;
295
296 // This is a non-product method that is helpful for testing. It is
297 // called at the end of a GC and artificially expands the heap by
298 // allocating a number of dead regions. This way we can induce very
299 // frequent marking cycles and stress the cleanup / concurrent
300 // cleanup code more (as all the regions that will be allocated by
301 // this method will be found dead by the marking cycle).
302 void allocate_dummy_regions() PRODUCT_RETURN;
303
304 // Clear RSets after a compaction. It also resets the GC time stamps.
305 void clear_rsets_post_compaction();
306
307 // If the HR printer is active, dump the state of the regions in the
308 // heap after a compaction.
309 void print_hrm_post_compaction();
310
311 // Create a memory mapper for auxiliary data structures of the given size and
312 // translation factor.
313 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description,
314 size_t size,
315 size_t translation_factor);
316
317 static G1Policy* create_g1_policy(STWGCTimer* gc_timer);
318
319 void trace_heap(GCWhen::Type when, const GCTracer* tracer);
320
321 // These are macros so that, if the assert fires, we get the correct
322 // line number, file, etc.
323
324 #define heap_locking_asserts_params(_extra_message_) \
325 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
326 (_extra_message_), \
327 BOOL_TO_STR(Heap_lock->owned_by_self()), \
328 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
329 BOOL_TO_STR(Thread::current()->is_VM_thread())
330
331 #define assert_heap_locked() \
332 do { \
333 assert(Heap_lock->owned_by_self(), \
334 heap_locking_asserts_params("should be holding the Heap_lock")); \
335 } while (0)
336
337 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
338 do { \
339 assert(Heap_lock->owned_by_self() || \
340 (SafepointSynchronize::is_at_safepoint() && \
341 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
342 heap_locking_asserts_params("should be holding the Heap_lock or " \
343 "should be at a safepoint")); \
344 } while (0)
345
346 #define assert_heap_locked_and_not_at_safepoint() \
347 do { \
348 assert(Heap_lock->owned_by_self() && \
349 !SafepointSynchronize::is_at_safepoint(), \
350 heap_locking_asserts_params("should be holding the Heap_lock and " \
351 "should not be at a safepoint")); \
352 } while (0)
353
354 #define assert_heap_not_locked() \
355 do { \
356 assert(!Heap_lock->owned_by_self(), \
357 heap_locking_asserts_params("should not be holding the Heap_lock")); \
358 } while (0)
359
360 #define assert_heap_not_locked_and_not_at_safepoint() \
361 do { \
362 assert(!Heap_lock->owned_by_self() && \
363 !SafepointSynchronize::is_at_safepoint(), \
364 heap_locking_asserts_params("should not be holding the Heap_lock and " \
365 "should not be at a safepoint")); \
366 } while (0)
367
368 #define assert_at_safepoint(_should_be_vm_thread_) \
369 do { \
370 assert(SafepointSynchronize::is_at_safepoint() && \
371 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
372 heap_locking_asserts_params("should be at a safepoint")); \
373 } while (0)
374
375 #define assert_not_at_safepoint() \
376 do { \
377 assert(!SafepointSynchronize::is_at_safepoint(), \
378 heap_locking_asserts_params("should not be at a safepoint")); \
379 } while (0)
380
381 protected:
382
383 // The young region list.
384 G1EdenRegions _eden;
385 G1SurvivorRegions _survivor;
386
387 STWGCTimer* _gc_timer_stw;
388
389 G1NewTracer* _gc_tracer_stw;
390
391 // The current policy object for the collector.
392 G1Policy* _g1_policy;
393 G1HeapSizingPolicy* _heap_sizing_policy;
394
395 G1CollectionSet _collection_set;
396
397 // This is the second level of trying to allocate a new region. If
398 // new_region() didn't find a region on the free_list, this call will
399 // check whether there's anything available on the
400 // secondary_free_list and/or wait for more regions to appear on
401 // that list, if _free_regions_coming is set.
402 HeapRegion* new_region_try_secondary_free_list(bool is_old);
403
404 // Try to allocate a single non-humongous HeapRegion sufficient for
405 // an allocation of the given word_size. If do_expand is true,
406 // attempt to expand the heap if necessary to satisfy the allocation
407 // request. If the region is to be used as an old region or for a
408 // humongous object, set is_old to true. If not, to false.
409 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand);
410
411 // Initialize a contiguous set of free regions of length num_regions
412 // and starting at index first so that they appear as a single
413 // humongous region.
414 HeapWord* humongous_obj_allocate_initialize_regions(uint first,
415 uint num_regions,
416 size_t word_size,
417 AllocationContext_t context);
418
419 // Attempt to allocate a humongous object of the given size. Return
420 // NULL if unsuccessful.
421 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context);
422
423 // The following two methods, allocate_new_tlab() and
424 // mem_allocate(), are the two main entry points from the runtime
425 // into the G1's allocation routines. They have the following
426 // assumptions:
427 //
428 // * They should both be called outside safepoints.
429 //
430 // * They should both be called without holding the Heap_lock.
431 //
432 // * All allocation requests for new TLABs should go to
433 // allocate_new_tlab().
434 //
435 // * All non-TLAB allocation requests should go to mem_allocate().
436 //
437 // * If either call cannot satisfy the allocation request using the
438 // current allocating region, they will try to get a new one. If
439 // this fails, they will attempt to do an evacuation pause and
440 // retry the allocation.
441 //
442 // * If all allocation attempts fail, even after trying to schedule
443 // an evacuation pause, allocate_new_tlab() will return NULL,
444 // whereas mem_allocate() will attempt a heap expansion and/or
445 // schedule a Full GC.
446 //
447 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
448 // should never be called with word_size being humongous. All
449 // humongous allocation requests should go to mem_allocate() which
450 // will satisfy them with a special path.
451
452 virtual HeapWord* allocate_new_tlab(size_t word_size);
453
454 virtual HeapWord* mem_allocate(size_t word_size,
455 bool* gc_overhead_limit_was_exceeded);
456
457 // The following three methods take a gc_count_before_ret
458 // parameter which is used to return the GC count if the method
459 // returns NULL. Given that we are required to read the GC count
460 // while holding the Heap_lock, and these paths will take the
461 // Heap_lock at some point, it's easier to get them to read the GC
462 // count while holding the Heap_lock before they return NULL instead
463 // of the caller (namely: mem_allocate()) having to also take the
464 // Heap_lock just to read the GC count.
465
466 // First-level mutator allocation attempt: try to allocate out of
467 // the mutator alloc region without taking the Heap_lock. This
468 // should only be used for non-humongous allocations.
469 inline HeapWord* attempt_allocation(size_t word_size,
470 uint* gc_count_before_ret,
471 uint* gclocker_retry_count_ret);
472
473 // Second-level mutator allocation attempt: take the Heap_lock and
474 // retry the allocation attempt, potentially scheduling a GC
475 // pause. This should only be used for non-humongous allocations.
476 HeapWord* attempt_allocation_slow(size_t word_size,
477 AllocationContext_t context,
478 uint* gc_count_before_ret,
479 uint* gclocker_retry_count_ret);
480
481 // Takes the Heap_lock and attempts a humongous allocation. It can
482 // potentially schedule a GC pause.
483 HeapWord* attempt_allocation_humongous(size_t word_size,
484 uint* gc_count_before_ret,
485 uint* gclocker_retry_count_ret);
486
487 // Allocation attempt that should be called during safepoints (e.g.,
488 // at the end of a successful GC). expect_null_mutator_alloc_region
489 // specifies whether the mutator alloc region is expected to be NULL
490 // or not.
491 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
492 AllocationContext_t context,
493 bool expect_null_mutator_alloc_region);
494
495 // These methods are the "callbacks" from the G1AllocRegion class.
496
497 // For mutator alloc regions.
498 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
499 void retire_mutator_alloc_region(HeapRegion* alloc_region,
500 size_t allocated_bytes);
501
502 // For GC alloc regions.
503 bool has_more_regions(InCSetState dest);
504 HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest);
505 void retire_gc_alloc_region(HeapRegion* alloc_region,
506 size_t allocated_bytes, InCSetState dest);
507
508 // - if explicit_gc is true, the GC is for a System.gc() etc,
509 // otherwise it's for a failed allocation.
510 // - if clear_all_soft_refs is true, all soft references should be
511 // cleared during the GC.
512 // - it returns false if it is unable to do the collection due to the
513 // GC locker being active, true otherwise.
514 bool do_full_collection(bool explicit_gc,
515 bool clear_all_soft_refs);
516
517 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread.
518 virtual void do_full_collection(bool clear_all_soft_refs);
519
520 // Resize the heap if necessary after a full collection.
521 void resize_if_necessary_after_full_collection();
522
523 // Callback from VM_G1CollectForAllocation operation.
524 // This function does everything necessary/possible to satisfy a
525 // failed allocation request (including collection, expansion, etc.)
526 HeapWord* satisfy_failed_allocation(size_t word_size,
527 AllocationContext_t context,
528 bool* succeeded);
529 private:
530 // Internal helpers used during full GC to split it up to
531 // increase readability.
532 void abort_concurrent_cycle();
533 void verify_before_full_collection(bool explicit_gc);
534 void prepare_heap_for_full_collection();
535 void prepare_heap_for_mutators();
536 void abort_refinement();
537 void verify_after_full_collection();
538 void print_heap_after_full_collection(G1HeapTransition* heap_transition);
539
540 // Helper method for satisfy_failed_allocation()
541 HeapWord* satisfy_failed_allocation_helper(size_t word_size,
542 AllocationContext_t context,
543 bool do_gc,
544 bool clear_all_soft_refs,
545 bool expect_null_mutator_alloc_region,
546 bool* gc_succeeded);
547
548 protected:
549 // Attempting to expand the heap sufficiently
550 // to support an allocation of the given "word_size". If
551 // successful, perform the allocation and return the address of the
552 // allocated block, or else "NULL".
553 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context);
554
555 // Preserve any referents discovered by concurrent marking that have not yet been
556 // copied by the STW pause.
557 void preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states);
558 // Process any reference objects discovered during
559 // an incremental evacuation pause.
560 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states);
561
562 // Enqueue any remaining discovered references
563 // after processing.
564 void enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states);
565
566 // Merges the information gathered on a per-thread basis for all worker threads
567 // during GC into global variables.
568 void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states);
569 public:
570 G1YoungRemSetSamplingThread* sampling_thread() const { return _young_gen_sampling_thread; }
571
572 WorkGang* workers() const { return _workers; }
573
574 G1Allocator* allocator() {
575 return _allocator;
576 }
577
578 G1HeapVerifier* verifier() {
579 return _verifier;
580 }
581
582 G1MonitoringSupport* g1mm() {
583 assert(_g1mm != NULL, "should have been initialized");
584 return _g1mm;
585 }
586
587 // Expand the garbage-first heap by at least the given size (in bytes!).
588 // Returns true if the heap was expanded by the requested amount;
589 // false otherwise.
590 // (Rounds up to a HeapRegion boundary.)
591 bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL);
592
593 // Returns the PLAB statistics for a given destination.
594 inline G1EvacStats* alloc_buffer_stats(InCSetState dest);
595
596 // Determines PLAB size for a given destination.
597 inline size_t desired_plab_sz(InCSetState dest);
598
599 inline AllocationContextStats& allocation_context_stats();
600
601 // Do anything common to GC's.
602 void gc_prologue(bool full);
603 void gc_epilogue(bool full);
604
605 // Modify the reclaim candidate set and test for presence.
606 // These are only valid for starts_humongous regions.
607 inline void set_humongous_reclaim_candidate(uint region, bool value);
608 inline bool is_humongous_reclaim_candidate(uint region);
609
610 // Remove from the reclaim candidate set. Also remove from the
611 // collection set so that later encounters avoid the slow path.
612 inline void set_humongous_is_live(oop obj);
613
614 // Register the given region to be part of the collection set.
615 inline void register_humongous_region_with_cset(uint index);
616 // Register regions with humongous objects (actually on the start region) in
617 // the in_cset_fast_test table.
618 void register_humongous_regions_with_cset();
619 // We register a region with the fast "in collection set" test. We
620 // simply set to true the array slot corresponding to this region.
621 void register_young_region_with_cset(HeapRegion* r) {
622 _in_cset_fast_test.set_in_young(r->hrm_index());
623 }
624 void register_old_region_with_cset(HeapRegion* r) {
625 _in_cset_fast_test.set_in_old(r->hrm_index());
626 }
627 inline void register_ext_region_with_cset(HeapRegion* r) {
628 _in_cset_fast_test.set_ext(r->hrm_index());
629 }
630 void clear_in_cset(const HeapRegion* hr) {
631 _in_cset_fast_test.clear(hr);
632 }
633
634 void clear_cset_fast_test() {
635 _in_cset_fast_test.clear();
636 }
637
638 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause);
639
640 // This is called at the start of either a concurrent cycle or a Full
641 // GC to update the number of old marking cycles started.
642 void increment_old_marking_cycles_started();
643
644 // This is called at the end of either a concurrent cycle or a Full
645 // GC to update the number of old marking cycles completed. Those two
646 // can happen in a nested fashion, i.e., we start a concurrent
647 // cycle, a Full GC happens half-way through it which ends first,
648 // and then the cycle notices that a Full GC happened and ends
649 // too. The concurrent parameter is a boolean to help us do a bit
650 // tighter consistency checking in the method. If concurrent is
651 // false, the caller is the inner caller in the nesting (i.e., the
652 // Full GC). If concurrent is true, the caller is the outer caller
653 // in this nesting (i.e., the concurrent cycle). Further nesting is
654 // not currently supported. The end of this call also notifies
655 // the FullGCCount_lock in case a Java thread is waiting for a full
656 // GC to happen (e.g., it called System.gc() with
657 // +ExplicitGCInvokesConcurrent).
658 void increment_old_marking_cycles_completed(bool concurrent);
659
660 uint old_marking_cycles_completed() {
661 return _old_marking_cycles_completed;
662 }
663
664 G1HRPrinter* hr_printer() { return &_hr_printer; }
665
666 // Allocates a new heap region instance.
667 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr);
668
669 // Allocate the highest free region in the reserved heap. This will commit
670 // regions as necessary.
671 HeapRegion* alloc_highest_free_region();
672
673 // Frees a non-humongous region by initializing its contents and
674 // adding it to the free list that's passed as a parameter (this is
675 // usually a local list which will be appended to the master free
676 // list later). The used bytes of freed regions are accumulated in
677 // pre_used. If skip_remset is true, the region's RSet will not be freed
678 // up. If skip_hot_card_cache is true, the region's hot card cache will not
679 // be freed up. The assumption is that this will be done later.
680 // The locked parameter indicates if the caller has already taken
681 // care of proper synchronization. This may allow some optimizations.
682 void free_region(HeapRegion* hr,
683 FreeRegionList* free_list,
684 bool skip_remset,
685 bool skip_hot_card_cache = false,
686 bool locked = false);
687
688 // It dirties the cards that cover the block so that the post
689 // write barrier never queues anything when updating objects on this
690 // block. It is assumed (and in fact we assert) that the block
691 // belongs to a young region.
692 inline void dirty_young_block(HeapWord* start, size_t word_size);
693
694 // Frees a humongous region by collapsing it into individual regions
695 // and calling free_region() for each of them. The freed regions
696 // will be added to the free list that's passed as a parameter (this
697 // is usually a local list which will be appended to the master free
698 // list later). The used bytes of freed regions are accumulated in
699 // pre_used. If skip_remset is true, the region's RSet will not be freed
700 // up. The assumption is that this will be done later.
701 void free_humongous_region(HeapRegion* hr,
702 FreeRegionList* free_list,
703 bool skip_remset);
704
705 // Facility for allocating in 'archive' regions in high heap memory and
706 // recording the allocated ranges. These should all be called from the
707 // VM thread at safepoints, without the heap lock held. They can be used
708 // to create and archive a set of heap regions which can be mapped at the
709 // same fixed addresses in a subsequent JVM invocation.
710 void begin_archive_alloc_range(bool open = false);
711
712 // Check if the requested size would be too large for an archive allocation.
713 bool is_archive_alloc_too_large(size_t word_size);
714
715 // Allocate memory of the requested size from the archive region. This will
716 // return NULL if the size is too large or if no memory is available. It
717 // does not trigger a garbage collection.
718 HeapWord* archive_mem_allocate(size_t word_size);
719
720 // Optionally aligns the end address and returns the allocated ranges in
721 // an array of MemRegions in order of ascending addresses.
722 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
723 size_t end_alignment_in_bytes = 0);
724
725 // Facility for allocating a fixed range within the heap and marking
726 // the containing regions as 'archive'. For use at JVM init time, when the
727 // caller may mmap archived heap data at the specified range(s).
728 // Verify that the MemRegions specified in the argument array are within the
729 // reserved heap.
730 bool check_archive_addresses(MemRegion* range, size_t count);
731
732 // Commit the appropriate G1 regions containing the specified MemRegions
733 // and mark them as 'archive' regions. The regions in the array must be
734 // non-overlapping and in order of ascending address.
735 bool alloc_archive_regions(MemRegion* range, size_t count, bool open);
736
737 // Insert any required filler objects in the G1 regions around the specified
738 // ranges to make the regions parseable. This must be called after
739 // alloc_archive_regions, and after class loading has occurred.
740 void fill_archive_regions(MemRegion* range, size_t count);
741
742 // For each of the specified MemRegions, uncommit the containing G1 regions
743 // which had been allocated by alloc_archive_regions. This should be called
744 // rather than fill_archive_regions at JVM init time if the archive file
745 // mapping failed, with the same non-overlapping and sorted MemRegion array.
746 void dealloc_archive_regions(MemRegion* range, size_t count);
747
748 protected:
749
750 // Shrink the garbage-first heap by at most the given size (in bytes!).
751 // (Rounds down to a HeapRegion boundary.)
752 virtual void shrink(size_t expand_bytes);
753 void shrink_helper(size_t expand_bytes);
754
755 #if TASKQUEUE_STATS
756 static void print_taskqueue_stats_hdr(outputStream* const st);
757 void print_taskqueue_stats() const;
758 void reset_taskqueue_stats();
759 #endif // TASKQUEUE_STATS
760
761 // Schedule the VM operation that will do an evacuation pause to
762 // satisfy an allocation request of word_size. *succeeded will
763 // return whether the VM operation was successful (it did do an
764 // evacuation pause) or not (another thread beat us to it or the GC
765 // locker was active). Given that we should not be holding the
766 // Heap_lock when we enter this method, we will pass the
767 // gc_count_before (i.e., total_collections()) as a parameter since
768 // it has to be read while holding the Heap_lock. Currently, both
769 // methods that call do_collection_pause() release the Heap_lock
770 // before the call, so it's easy to read gc_count_before just before.
771 HeapWord* do_collection_pause(size_t word_size,
772 uint gc_count_before,
773 bool* succeeded,
774 GCCause::Cause gc_cause);
775
776 void wait_for_root_region_scanning();
777
778 // The guts of the incremental collection pause, executed by the vm
779 // thread. It returns false if it is unable to do the collection due
780 // to the GC locker being active, true otherwise
781 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
782
783 // Actually do the work of evacuating the collection set.
784 virtual void evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states);
785
786 void pre_evacuate_collection_set();
787 void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss);
788
789 // Print the header for the per-thread termination statistics.
790 static void print_termination_stats_hdr();
791 // Print actual per-thread termination statistics.
792 void print_termination_stats(uint worker_id,
793 double elapsed_ms,
794 double strong_roots_ms,
795 double term_ms,
796 size_t term_attempts,
797 size_t alloc_buffer_waste,
798 size_t undo_waste) const;
799 // Update object copying statistics.
800 void record_obj_copy_mem_stats();
801
802 // The hot card cache for remembered set insertion optimization.
803 G1HotCardCache* _hot_card_cache;
804
805 // The g1 remembered set of the heap.
806 G1RemSet* _g1_rem_set;
807
808 // A set of cards that cover the objects for which the Rsets should be updated
809 // concurrently after the collection.
810 DirtyCardQueueSet _dirty_card_queue_set;
811
812 // After a collection pause, convert the regions in the collection set into free
813 // regions.
814 void free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words);
815
816 // Abandon the current collection set without recording policy
817 // statistics or updating free lists.
818 void abandon_collection_set(G1CollectionSet* collection_set);
819
820 // The concurrent marker (and the thread it runs in.)
821 G1ConcurrentMark* _cm;
822 ConcurrentMarkThread* _cmThread;
823
824 // The concurrent refiner.
825 G1ConcurrentRefine* _cr;
826
827 // The parallel task queues
828 RefToScanQueueSet *_task_queues;
829
830 // True iff a evacuation has failed in the current collection.
831 bool _evacuation_failed;
832
833 EvacuationFailedInfo* _evacuation_failed_info_array;
834
835 // Failed evacuations cause some logical from-space objects to have
836 // forwarding pointers to themselves. Reset them.
837 void remove_self_forwarding_pointers();
838
839 // Restore the objects in the regions in the collection set after an
840 // evacuation failure.
841 void restore_after_evac_failure();
842
843 PreservedMarksSet _preserved_marks_set;
844
845 // Preserve the mark of "obj", if necessary, in preparation for its mark
846 // word being overwritten with a self-forwarding-pointer.
847 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m);
848
849 #ifndef PRODUCT
850 // Support for forcing evacuation failures. Analogous to
851 // PromotionFailureALot for the other collectors.
852
853 // Records whether G1EvacuationFailureALot should be in effect
854 // for the current GC
855 bool _evacuation_failure_alot_for_current_gc;
856
857 // Used to record the GC number for interval checking when
858 // determining whether G1EvaucationFailureALot is in effect
859 // for the current GC.
860 size_t _evacuation_failure_alot_gc_number;
861
862 // Count of the number of evacuations between failures.
863 volatile size_t _evacuation_failure_alot_count;
864
865 // Set whether G1EvacuationFailureALot should be in effect
866 // for the current GC (based upon the type of GC and which
867 // command line flags are set);
868 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young,
869 bool during_initial_mark,
870 bool during_marking);
871
872 inline void set_evacuation_failure_alot_for_current_gc();
873
874 // Return true if it's time to cause an evacuation failure.
875 inline bool evacuation_should_fail();
876
877 // Reset the G1EvacuationFailureALot counters. Should be called at
878 // the end of an evacuation pause in which an evacuation failure occurred.
879 inline void reset_evacuation_should_fail();
880 #endif // !PRODUCT
881
882 // ("Weak") Reference processing support.
883 //
884 // G1 has 2 instances of the reference processor class. One
885 // (_ref_processor_cm) handles reference object discovery
886 // and subsequent processing during concurrent marking cycles.
887 //
888 // The other (_ref_processor_stw) handles reference object
889 // discovery and processing during full GCs and incremental
890 // evacuation pauses.
891 //
892 // During an incremental pause, reference discovery will be
893 // temporarily disabled for _ref_processor_cm and will be
894 // enabled for _ref_processor_stw. At the end of the evacuation
895 // pause references discovered by _ref_processor_stw will be
896 // processed and discovery will be disabled. The previous
897 // setting for reference object discovery for _ref_processor_cm
898 // will be re-instated.
899 //
900 // At the start of marking:
901 // * Discovery by the CM ref processor is verified to be inactive
902 // and it's discovered lists are empty.
903 // * Discovery by the CM ref processor is then enabled.
904 //
905 // At the end of marking:
906 // * Any references on the CM ref processor's discovered
907 // lists are processed (possibly MT).
908 //
909 // At the start of full GC we:
910 // * Disable discovery by the CM ref processor and
911 // empty CM ref processor's discovered lists
912 // (without processing any entries).
913 // * Verify that the STW ref processor is inactive and it's
914 // discovered lists are empty.
915 // * Temporarily set STW ref processor discovery as single threaded.
916 // * Temporarily clear the STW ref processor's _is_alive_non_header
917 // field.
918 // * Finally enable discovery by the STW ref processor.
919 //
920 // The STW ref processor is used to record any discovered
921 // references during the full GC.
922 //
923 // At the end of a full GC we:
924 // * Enqueue any reference objects discovered by the STW ref processor
925 // that have non-live referents. This has the side-effect of
926 // making the STW ref processor inactive by disabling discovery.
927 // * Verify that the CM ref processor is still inactive
928 // and no references have been placed on it's discovered
929 // lists (also checked as a precondition during initial marking).
930
931 // The (stw) reference processor...
932 ReferenceProcessor* _ref_processor_stw;
933
934 // During reference object discovery, the _is_alive_non_header
935 // closure (if non-null) is applied to the referent object to
936 // determine whether the referent is live. If so then the
937 // reference object does not need to be 'discovered' and can
938 // be treated as a regular oop. This has the benefit of reducing
939 // the number of 'discovered' reference objects that need to
940 // be processed.
941 //
942 // Instance of the is_alive closure for embedding into the
943 // STW reference processor as the _is_alive_non_header field.
944 // Supplying a value for the _is_alive_non_header field is
945 // optional but doing so prevents unnecessary additions to
946 // the discovered lists during reference discovery.
947 G1STWIsAliveClosure _is_alive_closure_stw;
948
949 // The (concurrent marking) reference processor...
950 ReferenceProcessor* _ref_processor_cm;
951
952 // Instance of the concurrent mark is_alive closure for embedding
953 // into the Concurrent Marking reference processor as the
954 // _is_alive_non_header field. Supplying a value for the
955 // _is_alive_non_header field is optional but doing so prevents
956 // unnecessary additions to the discovered lists during reference
957 // discovery.
958 G1CMIsAliveClosure _is_alive_closure_cm;
959
960 volatile bool _free_regions_coming;
961
962 public:
963
964 RefToScanQueue *task_queue(uint i) const;
965
966 uint num_task_queues() const;
967
968 // A set of cards where updates happened during the GC
969 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
970
971 // Create a G1CollectedHeap with the specified policy.
972 // Must call the initialize method afterwards.
973 // May not return if something goes wrong.
974 G1CollectedHeap(G1CollectorPolicy* policy);
975
976 private:
977 jint initialize_concurrent_refinement();
978 jint initialize_young_gen_sampling_thread();
979 public:
980 // Initialize the G1CollectedHeap to have the initial and
981 // maximum sizes and remembered and barrier sets
982 // specified by the policy object.
983 jint initialize();
984
985 virtual void stop();
986 virtual void safepoint_synchronize_begin();
987 virtual void safepoint_synchronize_end();
988
989 // Return the (conservative) maximum heap alignment for any G1 heap
990 static size_t conservative_max_heap_alignment();
991
992 // Does operations required after initialization has been done.
993 void post_initialize();
994
995 // Initialize weak reference processing.
996 void ref_processing_init();
997
998 virtual Name kind() const {
999 return CollectedHeap::G1CollectedHeap;
1000 }
1001
1002 virtual const char* name() const {
1003 return "G1";
1004 }
1005
1006 const G1CollectorState* collector_state() const { return &_collector_state; }
1007 G1CollectorState* collector_state() { return &_collector_state; }
1008
1009 // The current policy object for the collector.
1010 G1Policy* g1_policy() const { return _g1_policy; }
1011
1012 const G1CollectionSet* collection_set() const { return &_collection_set; }
1013 G1CollectionSet* collection_set() { return &_collection_set; }
1014
1015 virtual CollectorPolicy* collector_policy() const;
1016
1017 // Adaptive size policy. No such thing for g1.
1018 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
1019
1020 virtual GrowableArray<GCMemoryManager*> memory_managers();
1021 virtual GrowableArray<MemoryPool*> memory_pools();
1022
1023 // The rem set and barrier set.
1024 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
1025
1026 // Try to minimize the remembered set.
1027 void scrub_rem_set();
1028
1029 uint get_gc_time_stamp() {
1030 return _gc_time_stamp;
1031 }
1032
1033 inline void reset_gc_time_stamp();
1034
1035 void check_gc_time_stamps() PRODUCT_RETURN;
1036
1037 inline void increment_gc_time_stamp();
1038
1039 // Reset the given region's GC timestamp. If it's starts humongous,
1040 // also reset the GC timestamp of its corresponding
1041 // continues humongous regions too.
1042 void reset_gc_time_stamps(HeapRegion* hr);
1043
1044 // Apply the given closure on all cards in the Hot Card Cache, emptying it.
1045 void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i);
1046
1047 // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it.
1048 void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i);
1049
1050 // The shared block offset table array.
1051 G1BlockOffsetTable* bot() const { return _bot; }
1052
1053 // Reference Processing accessors
1054
1055 // The STW reference processor....
1056 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1057
1058 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; }
1059
1060 // The Concurrent Marking reference processor...
1061 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1062
1063 size_t unused_committed_regions_in_bytes() const;
1064 virtual size_t capacity() const;
1065 virtual size_t used() const;
1066 // This should be called when we're not holding the heap lock. The
1067 // result might be a bit inaccurate.
1068 size_t used_unlocked() const;
1069 size_t recalculate_used() const;
1070
1071 // These virtual functions do the actual allocation.
1072 // Some heaps may offer a contiguous region for shared non-blocking
1073 // allocation, via inlined code (by exporting the address of the top and
1074 // end fields defining the extent of the contiguous allocation region.)
1075 // But G1CollectedHeap doesn't yet support this.
1076
1077 virtual bool is_maximal_no_gc() const {
1078 return _hrm.available() == 0;
1079 }
1080
1081 // The current number of regions in the heap.
1082 uint num_regions() const { return _hrm.length(); }
1083
1084 // The max number of regions in the heap.
1085 uint max_regions() const { return _hrm.max_length(); }
1086
1087 // The number of regions that are completely free.
1088 uint num_free_regions() const { return _hrm.num_free_regions(); }
1089
1090 MemoryUsage get_auxiliary_data_memory_usage() const {
1091 return _hrm.get_auxiliary_data_memory_usage();
1092 }
1093
1094 // The number of regions that are not completely free.
1095 uint num_used_regions() const { return num_regions() - num_free_regions(); }
1096
1097 #ifdef ASSERT
1098 bool is_on_master_free_list(HeapRegion* hr) {
1099 return _hrm.is_free(hr);
1100 }
1101 #endif // ASSERT
1102
1103 // Wrapper for the region list operations that can be called from
1104 // methods outside this class.
1105
1106 void secondary_free_list_add(FreeRegionList* list) {
1107 _secondary_free_list.add_ordered(list);
1108 }
1109
1110 void append_secondary_free_list() {
1111 _hrm.insert_list_into_free_list(&_secondary_free_list);
1112 }
1113
1114 void append_secondary_free_list_if_not_empty_with_lock() {
1115 // If the secondary free list looks empty there's no reason to
1116 // take the lock and then try to append it.
1117 if (!_secondary_free_list.is_empty()) {
1118 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1119 append_secondary_free_list();
1120 }
1121 }
1122
1123 inline void old_set_add(HeapRegion* hr);
1124 inline void old_set_remove(HeapRegion* hr);
1125
1126 size_t non_young_capacity_bytes() {
1127 return (_old_set.length() + _humongous_set.length()) * HeapRegion::GrainBytes;
1128 }
1129
1130 void set_free_regions_coming();
1131 void reset_free_regions_coming();
1132 bool free_regions_coming() { return _free_regions_coming; }
1133 void wait_while_free_regions_coming();
1134
1135 // Determine whether the given region is one that we are using as an
1136 // old GC alloc region.
1137 bool is_old_gc_alloc_region(HeapRegion* hr);
1138
1139 // Perform a collection of the heap; intended for use in implementing
1140 // "System.gc". This probably implies as full a collection as the
1141 // "CollectedHeap" supports.
1142 virtual void collect(GCCause::Cause cause);
1143
1144 virtual bool copy_allocation_context_stats(const jint* contexts,
1145 jlong* totals,
1146 jbyte* accuracy,
1147 jint len);
1148
1149 // True iff an evacuation has failed in the most-recent collection.
1150 bool evacuation_failed() { return _evacuation_failed; }
1151
1152 void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed);
1153 void prepend_to_freelist(FreeRegionList* list);
1154 void decrement_summary_bytes(size_t bytes);
1155
1156 virtual bool is_in(const void* p) const;
1157 #ifdef ASSERT
1158 // Returns whether p is in one of the available areas of the heap. Slow but
1159 // extensive version.
1160 bool is_in_exact(const void* p) const;
1161 #endif
1162
1163 // Return "TRUE" iff the given object address is within the collection
1164 // set. Assumes that the reference points into the heap.
1165 inline bool is_in_cset(const HeapRegion *hr);
1166 inline bool is_in_cset(oop obj);
1167 inline bool is_in_cset(HeapWord* addr);
1168
1169 inline bool is_in_cset_or_humongous(const oop obj);
1170
1171 private:
1172 // This array is used for a quick test on whether a reference points into
1173 // the collection set or not. Each of the array's elements denotes whether the
1174 // corresponding region is in the collection set or not.
1175 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test;
1176
1177 public:
1178
1179 inline InCSetState in_cset_state(const oop obj);
1180
1181 // Return "TRUE" iff the given object address is in the reserved
1182 // region of g1.
1183 bool is_in_g1_reserved(const void* p) const {
1184 return _hrm.reserved().contains(p);
1185 }
1186
1187 // Returns a MemRegion that corresponds to the space that has been
1188 // reserved for the heap
1189 MemRegion g1_reserved() const {
1190 return _hrm.reserved();
1191 }
1192
1193 virtual bool is_in_closed_subset(const void* p) const;
1194
1195 G1SATBCardTableLoggingModRefBS* g1_barrier_set() {
1196 return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set());
1197 }
1198
1199 G1HotCardCache* g1_hot_card_cache() const { return _hot_card_cache; }
1200
1201 // Iteration functions.
1202
1203 // Iterate over all objects, calling "cl.do_object" on each.
1204 virtual void object_iterate(ObjectClosure* cl);
1205
1206 virtual void safe_object_iterate(ObjectClosure* cl) {
1207 object_iterate(cl);
1208 }
1209
1210 // Iterate over heap regions, in address order, terminating the
1211 // iteration early if the "doHeapRegion" method returns "true".
1212 void heap_region_iterate(HeapRegionClosure* blk) const;
1213
1214 // Return the region with the given index. It assumes the index is valid.
1215 inline HeapRegion* region_at(uint index) const;
1216
1217 // Return the next region (by index) that is part of the same
1218 // humongous object that hr is part of.
1219 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const;
1220
1221 // Calculate the region index of the given address. Given address must be
1222 // within the heap.
1223 inline uint addr_to_region(HeapWord* addr) const;
1224
1225 inline HeapWord* bottom_addr_for_region(uint index) const;
1226
1227 // Two functions to iterate over the heap regions in parallel. Threads
1228 // compete using the HeapRegionClaimer to claim the regions before
1229 // applying the closure on them.
1230 // The _from_worker_offset version uses the HeapRegionClaimer and
1231 // the worker id to calculate a start offset to prevent all workers to
1232 // start from the point.
1233 void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
1234 HeapRegionClaimer* hrclaimer,
1235 uint worker_id) const;
1236
1237 void heap_region_par_iterate_from_start(HeapRegionClosure* cl,
1238 HeapRegionClaimer* hrclaimer) const;
1239
1240 // Iterate over the regions (if any) in the current collection set.
1241 void collection_set_iterate(HeapRegionClosure* blk);
1242
1243 // Iterate over the regions (if any) in the current collection set. Starts the
1244 // iteration over the entire collection set so that the start regions of a given
1245 // worker id over the set active_workers are evenly spread across the set of
1246 // collection set regions.
1247 void collection_set_iterate_from(HeapRegionClosure *blk, uint worker_id);
1248
1249 // Returns the HeapRegion that contains addr. addr must not be NULL.
1250 template <class T>
1251 inline HeapRegion* heap_region_containing(const T addr) const;
1252
1253 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1254 // each address in the (reserved) heap is a member of exactly
1255 // one block. The defining characteristic of a block is that it is
1256 // possible to find its size, and thus to progress forward to the next
1257 // block. (Blocks may be of different sizes.) Thus, blocks may
1258 // represent Java objects, or they might be free blocks in a
1259 // free-list-based heap (or subheap), as long as the two kinds are
1260 // distinguishable and the size of each is determinable.
1261
1262 // Returns the address of the start of the "block" that contains the
1263 // address "addr". We say "blocks" instead of "object" since some heaps
1264 // may not pack objects densely; a chunk may either be an object or a
1265 // non-object.
1266 virtual HeapWord* block_start(const void* addr) const;
1267
1268 // Requires "addr" to be the start of a chunk, and returns its size.
1269 // "addr + size" is required to be the start of a new chunk, or the end
1270 // of the active area of the heap.
1271 virtual size_t block_size(const HeapWord* addr) const;
1272
1273 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1274 // the block is an object.
1275 virtual bool block_is_obj(const HeapWord* addr) const;
1276
1277 // Section on thread-local allocation buffers (TLABs)
1278 // See CollectedHeap for semantics.
1279
1280 bool supports_tlab_allocation() const;
1281 size_t tlab_capacity(Thread* ignored) const;
1282 size_t tlab_used(Thread* ignored) const;
1283 size_t max_tlab_size() const;
1284 size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1285
1286 // Can a compiler initialize a new object without store barriers?
1287 // This permission only extends from the creation of a new object
1288 // via a TLAB up to the first subsequent safepoint. If such permission
1289 // is granted for this heap type, the compiler promises to call
1290 // defer_store_barrier() below on any slow path allocation of
1291 // a new object for which such initializing store barriers will
1292 // have been elided. G1, like CMS, allows this, but should be
1293 // ready to provide a compensating write barrier as necessary
1294 // if that storage came out of a non-young region. The efficiency
1295 // of this implementation depends crucially on being able to
1296 // answer very efficiently in constant time whether a piece of
1297 // storage in the heap comes from a young region or not.
1298 // See ReduceInitialCardMarks.
1299 virtual bool can_elide_tlab_store_barriers() const {
1300 return true;
1301 }
1302
1303 virtual bool card_mark_must_follow_store() const {
1304 return true;
1305 }
1306
1307 inline bool is_in_young(const oop obj);
1308
1309 // We don't need barriers for initializing stores to objects
1310 // in the young gen: for the SATB pre-barrier, there is no
1311 // pre-value that needs to be remembered; for the remembered-set
1312 // update logging post-barrier, we don't maintain remembered set
1313 // information for young gen objects.
1314 virtual inline bool can_elide_initializing_store_barrier(oop new_obj);
1315
1316 // Returns "true" iff the given word_size is "very large".
1317 static bool is_humongous(size_t word_size) {
1318 // Note this has to be strictly greater-than as the TLABs
1319 // are capped at the humongous threshold and we want to
1320 // ensure that we don't try to allocate a TLAB as
1321 // humongous and that we don't allocate a humongous
1322 // object in a TLAB.
1323 return word_size > _humongous_object_threshold_in_words;
1324 }
1325
1326 // Returns the humongous threshold for a specific region size
1327 static size_t humongous_threshold_for(size_t region_size) {
1328 return (region_size / 2);
1329 }
1330
1331 // Returns the number of regions the humongous object of the given word size
1332 // requires.
1333 static size_t humongous_obj_size_in_regions(size_t word_size);
1334
1335 // Print the maximum heap capacity.
1336 virtual size_t max_capacity() const;
1337
1338 virtual jlong millis_since_last_gc();
1339
1340
1341 // Convenience function to be used in situations where the heap type can be
1342 // asserted to be this type.
1343 static G1CollectedHeap* heap();
1344
1345 void set_region_short_lived_locked(HeapRegion* hr);
1346 // add appropriate methods for any other surv rate groups
1347
1348 const G1SurvivorRegions* survivor() const { return &_survivor; }
1349
1350 uint survivor_regions_count() const {
1351 return _survivor.length();
1352 }
1353
1354 uint eden_regions_count() const {
1355 return _eden.length();
1356 }
1357
1358 uint young_regions_count() const {
1359 return _eden.length() + _survivor.length();
1360 }
1361
1362 uint old_regions_count() const { return _old_set.length(); }
1363
1364 uint humongous_regions_count() const { return _humongous_set.length(); }
1365
1366 #ifdef ASSERT
1367 bool check_young_list_empty();
1368 #endif
1369
1370 // *** Stuff related to concurrent marking. It's not clear to me that so
1371 // many of these need to be public.
1372
1373 // The functions below are helper functions that a subclass of
1374 // "CollectedHeap" can use in the implementation of its virtual
1375 // functions.
1376 // This performs a concurrent marking of the live objects in a
1377 // bitmap off to the side.
1378 void doConcurrentMark();
1379
1380 bool isMarkedNext(oop obj) const;
1381
1382 // Determine if an object is dead, given the object and also
1383 // the region to which the object belongs. An object is dead
1384 // iff a) it was not allocated since the last mark, b) it
1385 // is not marked, and c) it is not in an archive region.
1386 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1387 return
1388 hr->is_obj_dead(obj, _cm->prev_mark_bitmap()) &&
1389 !hr->is_archive();
1390 }
1391
1392 // This function returns true when an object has been
1393 // around since the previous marking and hasn't yet
1394 // been marked during this marking, and is not in an archive region.
1395 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1396 return
1397 !hr->obj_allocated_since_next_marking(obj) &&
1398 !isMarkedNext(obj) &&
1399 !hr->is_archive();
1400 }
1401
1402 // Determine if an object is dead, given only the object itself.
1403 // This will find the region to which the object belongs and
1404 // then call the region version of the same function.
1405
1406 // Added if it is NULL it isn't dead.
1407
1408 inline bool is_obj_dead(const oop obj) const;
1409
1410 inline bool is_obj_ill(const oop obj) const;
1411
1412 inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const;
1413 inline bool is_obj_dead_full(const oop obj) const;
1414
1415 G1ConcurrentMark* concurrent_mark() const { return _cm; }
1416
1417 // Refinement
1418
1419 G1ConcurrentRefine* concurrent_refine() const { return _cr; }
1420
1421 // Optimized nmethod scanning support routines
1422
1423 // Is an oop scavengeable
1424 virtual bool is_scavengable(oop obj);
1425
1426 // Register the given nmethod with the G1 heap.
1427 virtual void register_nmethod(nmethod* nm);
1428
1429 // Unregister the given nmethod from the G1 heap.
1430 virtual void unregister_nmethod(nmethod* nm);
1431
1432 // Free up superfluous code root memory.
1433 void purge_code_root_memory();
1434
1435 // Rebuild the strong code root lists for each region
1436 // after a full GC.
1437 void rebuild_strong_code_roots();
1438
1439 // Partial cleaning used when class unloading is disabled.
1440 // Let the caller choose what structures to clean out:
1441 // - StringTable
1442 // - SymbolTable
1443 // - StringDeduplication structures
1444 void partial_cleaning(BoolObjectClosure* is_alive, bool unlink_strings, bool unlink_symbols, bool unlink_string_dedup);
1445
1446 // Complete cleaning used when class unloading is enabled.
1447 // Cleans out all structures handled by partial_cleaning and also the CodeCache.
1448 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred);
1449
1450 // Redirty logged cards in the refinement queue.
1451 void redirty_logged_cards();
1452 // Verification
1453
1454 // Perform any cleanup actions necessary before allowing a verification.
1455 virtual void prepare_for_verify();
1456
1457 // Perform verification.
1458
1459 // vo == UsePrevMarking -> use "prev" marking information,
1460 // vo == UseNextMarking -> use "next" marking information
1461 // vo == UseFullMarking -> use "next" marking bitmap but no TAMS
1462 //
1463 // NOTE: Only the "prev" marking information is guaranteed to be
1464 // consistent most of the time, so most calls to this should use
1465 // vo == UsePrevMarking.
1466 // Currently, there is only one case where this is called with
1467 // vo == UseNextMarking, which is to verify the "next" marking
1468 // information at the end of remark.
1469 // Currently there is only one place where this is called with
1470 // vo == UseFullMarking, which is to verify the marking during a
1471 // full GC.
1472 void verify(VerifyOption vo);
1473
1474 // WhiteBox testing support.
1475 virtual bool supports_concurrent_phase_control() const;
1476 virtual const char* const* concurrent_phases() const;
1477 virtual bool request_concurrent_phase(const char* phase);
1478
1479 // The methods below are here for convenience and dispatch the
1480 // appropriate method depending on value of the given VerifyOption
1481 // parameter. The values for that parameter, and their meanings,
1482 // are the same as those above.
1483
1484 bool is_obj_dead_cond(const oop obj,
1485 const HeapRegion* hr,
1486 const VerifyOption vo) const;
1487
1488 bool is_obj_dead_cond(const oop obj,
1489 const VerifyOption vo) const;
1490
1491 G1HeapSummary create_g1_heap_summary();
1492 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats);
1493
1494 // Printing
1495 private:
1496 void print_heap_regions() const;
1497 void print_regions_on(outputStream* st) const;
1498
1499 public:
1500 virtual void print_on(outputStream* st) const;
1501 virtual void print_extended_on(outputStream* st) const;
1502 virtual void print_on_error(outputStream* st) const;
1503
1504 virtual void print_gc_threads_on(outputStream* st) const;
1505 virtual void gc_threads_do(ThreadClosure* tc) const;
1506
1507 // Override
1508 void print_tracing_info() const;
1509
1510 // The following two methods are helpful for debugging RSet issues.
1511 void print_cset_rsets() PRODUCT_RETURN;
1512 void print_all_rsets() PRODUCT_RETURN;
1513
1514 public:
1515 size_t pending_card_num();
1516
1517 protected:
1518 size_t _max_heap_capacity;
1519 };
1520
1521 class G1ParEvacuateFollowersClosure : public VoidClosure {
1522 private:
1523 double _start_term;
1524 double _term_time;
1525 size_t _term_attempts;
1526
1527 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
1528 void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
1529 protected:
1530 G1CollectedHeap* _g1h;
1531 G1ParScanThreadState* _par_scan_state;
1532 RefToScanQueueSet* _queues;
1533 ParallelTaskTerminator* _terminator;
1534
1535 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
1536 RefToScanQueueSet* queues() { return _queues; }
1537 ParallelTaskTerminator* terminator() { return _terminator; }
1538
1539 public:
1540 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
1541 G1ParScanThreadState* par_scan_state,
1542 RefToScanQueueSet* queues,
1543 ParallelTaskTerminator* terminator)
1544 : _g1h(g1h), _par_scan_state(par_scan_state),
1545 _queues(queues), _terminator(terminator),
1546 _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
1547
1548 void do_void();
1549
1550 double term_time() const { return _term_time; }
1551 size_t term_attempts() const { return _term_attempts; }
1552
1553 private:
1554 inline bool offer_termination();
1555 };
1556
1557 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP