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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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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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/hSpaceCounters.hpp"
46 #include "gc/g1/heapRegionManager.hpp"
47 #include "gc/g1/heapRegionSet.hpp"
48 #include "gc/shared/barrierSet.hpp"
49 #include "gc/shared/collectedHeap.hpp"
50 #include "gc/shared/plab.hpp"
51 #include "gc/shared/preservedMarks.hpp"
52 #include "memory/memRegion.hpp"
53 #include "utilities/stack.hpp"
54
55 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
56 // It uses the "Garbage First" heap organization and algorithm, which
57 // may combine concurrent marking with parallel, incremental compaction of
58 // heap subsets that will yield large amounts of garbage.
59
60 // Forward declarations
61 class HeapRegion;
62 class HRRSCleanupTask;
63 class GenerationSpec;
64 class G1ParScanThreadState;
65 class G1ParScanThreadStateSet;
66 class G1ParScanThreadState;
67 class ObjectClosure;
68 class SpaceClosure;
69 class CompactibleSpaceClosure;
70 class Space;
71 class G1CollectionSet;
72 class G1CollectorPolicy;
73 class G1Policy;
74 class G1HotCardCache;
75 class G1RemSet;
76 class G1YoungRemSetSamplingThread;
77 class HeapRegionRemSetIterator;
78 class G1ConcurrentMark;
79 class ConcurrentMarkThread;
80 class G1ConcurrentRefine;
81 class GenerationCounters;
82 class STWGCTimer;
83 class G1NewTracer;
84 class EvacuationFailedInfo;
85 class nmethod;
86 class Ticks;
87 class WorkGang;
88 class G1Allocator;
89 class G1ArchiveAllocator;
90 class G1FullGCScope;
91 class G1HeapVerifier;
92 class G1HeapSizingPolicy;
93 class G1HeapSummary;
94 class G1EvacSummary;
95 class MemoryManager;
96 class MemoryPool;
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 G1GCAllocRegion;
132 friend class G1HeapVerifier;
133
134 // Closures used in implementation.
135 friend class G1ParScanThreadState;
136 friend class G1ParScanThreadStateSet;
137 friend class G1ParTask;
138 friend class G1PLABAllocator;
139 friend class G1PrepareCompactClosure;
140
141 // Other related classes.
142 friend class HeapRegionClaimer;
143
144 // Testing classes.
145 friend class G1CheckCSetFastTableClosure;
146
147 private:
148 G1YoungRemSetSamplingThread* _young_gen_sampling_thread;
149
150 WorkGang* _workers;
151 G1CollectorPolicy* _collector_policy;
152
153 GCMemoryManager* _minor_mgr;
154 GCMemoryManager* _major_mgr;
155
156 static size_t _humongous_object_threshold_in_words;
157
158 // The secondary free list which contains regions that have been
159 // freed up during the cleanup process. This will be appended to
160 // the master free list when appropriate.
161 FreeRegionList _secondary_free_list;
162
163 // It keeps track of the old regions.
164 HeapRegionSet _old_set;
165
166 // It keeps track of the humongous regions.
167 HeapRegionSet _humongous_set;
168
169 void eagerly_reclaim_humongous_regions();
170 // Start a new incremental collection set for the next pause.
171 void start_new_collection_set();
172
173 // The number of regions we could create by expansion.
174 uint _expansion_regions;
175
176 // The block offset table for the G1 heap.
177 G1BlockOffsetTable* _bot;
178
179 // Tears down the region sets / lists so that they are empty and the
180 // regions on the heap do not belong to a region set / list. The
181 // only exception is the humongous set which we leave unaltered. If
182 // free_list_only is true, it will only tear down the master free
183 // list. It is called before a Full GC (free_list_only == false) or
184 // before heap shrinking (free_list_only == true).
185 void tear_down_region_sets(bool free_list_only);
186
187 // Rebuilds the region sets / lists so that they are repopulated to
188 // reflect the contents of the heap. The only exception is the
189 // humongous set which was not torn down in the first place. If
190 // free_list_only is true, it will only rebuild the master free
191 // list. It is called after a Full GC (free_list_only == false) or
192 // after heap shrinking (free_list_only == true).
193 void rebuild_region_sets(bool free_list_only);
194
195 // Callback for region mapping changed events.
196 G1RegionMappingChangedListener _listener;
197
198 // The sequence of all heap regions in the heap.
199 HeapRegionManager _hrm;
200
201 // Manages all allocations with regions except humongous object allocations.
202 G1Allocator* _allocator;
203
204 // Manages all heap verification.
205 G1HeapVerifier* _verifier;
206
207 // Outside of GC pauses, the number of bytes used in all regions other
208 // than the current allocation region(s).
209 size_t _summary_bytes_used;
210
211 void increase_used(size_t bytes);
212 void decrease_used(size_t bytes);
213
214 void set_used(size_t bytes);
215
216 // Class that handles archive allocation ranges.
217 G1ArchiveAllocator* _archive_allocator;
218
219 // Statistics for each allocation context
220 AllocationContextStats _allocation_context_stats;
221
222 // GC allocation statistics policy for survivors.
223 G1EvacStats _survivor_evac_stats;
224
225 // GC allocation statistics policy for tenured objects.
226 G1EvacStats _old_evac_stats;
227
228 // It specifies whether we should attempt to expand the heap after a
229 // region allocation failure. If heap expansion fails we set this to
230 // false so that we don't re-attempt the heap expansion (it's likely
231 // that subsequent expansion attempts will also fail if one fails).
232 // Currently, it is only consulted during GC and it's reset at the
233 // start of each GC.
234 bool _expand_heap_after_alloc_failure;
235
236 // Helper for monitoring and management support.
237 G1MonitoringSupport* _g1mm;
238
239 // Records whether the region at the given index is (still) a
240 // candidate for eager reclaim. Only valid for humongous start
241 // regions; other regions have unspecified values. Humongous start
242 // regions are initialized at start of collection pause, with
243 // candidates removed from the set as they are found reachable from
244 // roots or the young generation.
245 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> {
246 protected:
247 bool default_value() const { return false; }
248 public:
249 void clear() { G1BiasedMappedArray<bool>::clear(); }
250 void set_candidate(uint region, bool value) {
251 set_by_index(region, value);
252 }
253 bool is_candidate(uint region) {
254 return get_by_index(region);
255 }
256 };
257
258 HumongousReclaimCandidates _humongous_reclaim_candidates;
259 // Stores whether during humongous object registration we found candidate regions.
260 // If not, we can skip a few steps.
261 bool _has_humongous_reclaim_candidates;
262
263 volatile uint _gc_time_stamp;
264
265 G1HRPrinter _hr_printer;
266
267 // It decides whether an explicit GC should start a concurrent cycle
268 // instead of doing a STW GC. Currently, a concurrent cycle is
269 // explicitly started if:
270 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
271 // (b) cause == _g1_humongous_allocation
272 // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
273 // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent.
274 // (e) cause == _update_allocation_context_stats_inc
275 // (f) cause == _wb_conc_mark
276 bool should_do_concurrent_full_gc(GCCause::Cause cause);
277
278 // indicates whether we are in young or mixed GC mode
279 G1CollectorState _collector_state;
280
281 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
282 // concurrent cycles) we have started.
283 volatile uint _old_marking_cycles_started;
284
285 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
286 // concurrent cycles) we have completed.
287 volatile uint _old_marking_cycles_completed;
288
289 // This is a non-product method that is helpful for testing. It is
290 // called at the end of a GC and artificially expands the heap by
291 // allocating a number of dead regions. This way we can induce very
292 // frequent marking cycles and stress the cleanup / concurrent
293 // cleanup code more (as all the regions that will be allocated by
294 // this method will be found dead by the marking cycle).
295 void allocate_dummy_regions() PRODUCT_RETURN;
296
297 // Clear RSets after a compaction. It also resets the GC time stamps.
298 void clear_rsets_post_compaction();
299
300 // If the HR printer is active, dump the state of the regions in the
301 // heap after a compaction.
302 void print_hrm_post_compaction();
303
304 // Create a memory mapper for auxiliary data structures of the given size and
305 // translation factor.
306 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description,
307 size_t size,
308 size_t translation_factor);
309
310 static G1Policy* create_g1_policy(STWGCTimer* gc_timer);
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(_should_be_vm_thread_) \
362 do { \
363 assert(SafepointSynchronize::is_at_safepoint() && \
364 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
365 heap_locking_asserts_params("should be at a safepoint")); \
366 } while (0)
367
368 #define assert_not_at_safepoint() \
369 do { \
370 assert(!SafepointSynchronize::is_at_safepoint(), \
371 heap_locking_asserts_params("should not be at a safepoint")); \
372 } while (0)
373
374 protected:
375
376 // The young region list.
377 G1EdenRegions _eden;
378 G1SurvivorRegions _survivor;
379
380 STWGCTimer* _gc_timer_stw;
381
382 G1NewTracer* _gc_tracer_stw;
383
384 // The current policy object for the collector.
385 G1Policy* _g1_policy;
386 G1HeapSizingPolicy* _heap_sizing_policy;
387
388 G1CollectionSet _collection_set;
389
390 // This is the second level of trying to allocate a new region. If
391 // new_region() didn't find a region on the free_list, this call will
392 // check whether there's anything available on the
393 // secondary_free_list and/or wait for more regions to appear on
394 // that list, if _free_regions_coming is set.
395 HeapRegion* new_region_try_secondary_free_list(bool is_old);
396
397 // Try to allocate a single non-humongous HeapRegion sufficient for
398 // an allocation of the given word_size. If do_expand is true,
399 // attempt to expand the heap if necessary to satisfy the allocation
400 // request. If the region is to be used as an old region or for a
401 // humongous object, set is_old to true. If not, to false.
402 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand);
403
404 // Initialize a contiguous set of free regions of length num_regions
405 // and starting at index first so that they appear as a single
406 // humongous region.
407 HeapWord* humongous_obj_allocate_initialize_regions(uint first,
408 uint num_regions,
409 size_t word_size,
410 AllocationContext_t context);
411
412 // Attempt to allocate a humongous object of the given size. Return
413 // NULL if unsuccessful.
414 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context);
415
416 // The following two methods, allocate_new_tlab() and
417 // mem_allocate(), are the two main entry points from the runtime
418 // into the G1's allocation routines. They have the following
419 // assumptions:
420 //
421 // * They should both be called outside safepoints.
422 //
423 // * They should both be called without holding the Heap_lock.
424 //
425 // * All allocation requests for new TLABs should go to
426 // allocate_new_tlab().
427 //
428 // * All non-TLAB allocation requests should go to mem_allocate().
429 //
430 // * If either call cannot satisfy the allocation request using the
431 // current allocating region, they will try to get a new one. If
432 // this fails, they will attempt to do an evacuation pause and
433 // retry the allocation.
434 //
435 // * If all allocation attempts fail, even after trying to schedule
436 // an evacuation pause, allocate_new_tlab() will return NULL,
437 // whereas mem_allocate() will attempt a heap expansion and/or
438 // schedule a Full GC.
439 //
440 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
441 // should never be called with word_size being humongous. All
442 // humongous allocation requests should go to mem_allocate() which
443 // will satisfy them with a special path.
444
445 virtual HeapWord* allocate_new_tlab(size_t word_size);
446
447 virtual HeapWord* mem_allocate(size_t word_size,
448 bool* gc_overhead_limit_was_exceeded);
449
450 // The following three methods take a gc_count_before_ret
451 // parameter which is used to return the GC count if the method
452 // returns NULL. Given that we are required to read the GC count
453 // while holding the Heap_lock, and these paths will take the
454 // Heap_lock at some point, it's easier to get them to read the GC
455 // count while holding the Heap_lock before they return NULL instead
456 // of the caller (namely: mem_allocate()) having to also take the
457 // Heap_lock just to read the GC count.
458
459 // First-level mutator allocation attempt: try to allocate out of
460 // the mutator alloc region without taking the Heap_lock. This
461 // should only be used for non-humongous allocations.
462 inline HeapWord* attempt_allocation(size_t word_size,
463 uint* gc_count_before_ret,
464 uint* gclocker_retry_count_ret);
465
466 // Second-level mutator allocation attempt: take the Heap_lock and
467 // retry the allocation attempt, potentially scheduling a GC
468 // pause. This should only be used for non-humongous allocations.
469 HeapWord* attempt_allocation_slow(size_t word_size,
470 AllocationContext_t context,
471 uint* gc_count_before_ret,
472 uint* gclocker_retry_count_ret);
473
474 // Takes the Heap_lock and attempts a humongous allocation. It can
475 // potentially schedule a GC pause.
476 HeapWord* attempt_allocation_humongous(size_t word_size,
477 uint* gc_count_before_ret,
478 uint* gclocker_retry_count_ret);
479
480 // Allocation attempt that should be called during safepoints (e.g.,
481 // at the end of a successful GC). expect_null_mutator_alloc_region
482 // specifies whether the mutator alloc region is expected to be NULL
483 // or not.
484 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
485 AllocationContext_t context,
486 bool expect_null_mutator_alloc_region);
487
488 // These methods are the "callbacks" from the G1AllocRegion class.
489
490 // For mutator alloc regions.
491 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
492 void retire_mutator_alloc_region(HeapRegion* alloc_region,
493 size_t allocated_bytes);
494
495 // For GC alloc regions.
496 bool has_more_regions(InCSetState dest);
497 HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest);
498 void retire_gc_alloc_region(HeapRegion* alloc_region,
499 size_t allocated_bytes, InCSetState dest);
500
501 // - if explicit_gc is true, the GC is for a System.gc() etc,
502 // otherwise it's for a failed allocation.
503 // - if clear_all_soft_refs is true, all soft references should be
504 // cleared during the GC.
505 // - it returns false if it is unable to do the collection due to the
506 // GC locker being active, true otherwise.
507 bool do_full_collection(bool explicit_gc,
508 bool clear_all_soft_refs);
509
510 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread.
511 virtual void do_full_collection(bool clear_all_soft_refs);
512
513 // Resize the heap if necessary after a full collection.
514 void resize_if_necessary_after_full_collection();
515
516 // Callback from VM_G1CollectForAllocation operation.
517 // This function does everything necessary/possible to satisfy a
518 // failed allocation request (including collection, expansion, etc.)
519 HeapWord* satisfy_failed_allocation(size_t word_size,
520 AllocationContext_t context,
521 bool* succeeded);
522 private:
523 // Internal helpers used during full GC to split it up to
524 // increase readability.
525 void do_full_collection_inner(G1FullGCScope* scope);
526 void abort_concurrent_cycle();
527 void verify_before_full_collection(bool explicit_gc);
528 void prepare_heap_for_full_collection();
529 void prepare_heap_for_mutators();
530 void abort_refinement();
531 void verify_after_full_collection();
532 void print_heap_after_full_collection(G1HeapTransition* heap_transition);
533
534 // Helper method for satisfy_failed_allocation()
535 HeapWord* satisfy_failed_allocation_helper(size_t word_size,
536 AllocationContext_t context,
537 bool do_gc,
538 bool clear_all_soft_refs,
539 bool expect_null_mutator_alloc_region,
540 bool* gc_succeeded);
541
542 protected:
543 // Attempting to expand the heap sufficiently
544 // to support an allocation of the given "word_size". If
545 // successful, perform the allocation and return the address of the
546 // allocated block, or else "NULL".
547 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context);
548
549 // Preserve any referents discovered by concurrent marking that have not yet been
550 // copied by the STW pause.
551 void preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states);
552 // Process any reference objects discovered during
553 // an incremental evacuation pause.
554 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states);
555
556 // Enqueue any remaining discovered references
557 // after processing.
558 void enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states);
559
560 // Merges the information gathered on a per-thread basis for all worker threads
561 // during GC into global variables.
562 void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states);
563 public:
564 G1YoungRemSetSamplingThread* sampling_thread() const { return _young_gen_sampling_thread; }
565
566 WorkGang* workers() const { return _workers; }
567
568 G1Allocator* allocator() {
569 return _allocator;
570 }
571
572 G1HeapVerifier* verifier() {
573 return _verifier;
574 }
575
576 G1MonitoringSupport* g1mm() {
577 assert(_g1mm != NULL, "should have been initialized");
578 return _g1mm;
579 }
580
581 // Expand the garbage-first heap by at least the given size (in bytes!).
582 // Returns true if the heap was expanded by the requested amount;
583 // false otherwise.
584 // (Rounds up to a HeapRegion boundary.)
585 bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL);
586
587 // Returns the PLAB statistics for a given destination.
588 inline G1EvacStats* alloc_buffer_stats(InCSetState dest);
589
590 // Determines PLAB size for a given destination.
591 inline size_t desired_plab_sz(InCSetState dest);
592
593 inline AllocationContextStats& allocation_context_stats();
594
595 // Do anything common to GC's.
596 void gc_prologue(bool full);
597 void gc_epilogue(bool full);
598
599 // Modify the reclaim candidate set and test for presence.
600 // These are only valid for starts_humongous regions.
601 inline void set_humongous_reclaim_candidate(uint region, bool value);
602 inline bool is_humongous_reclaim_candidate(uint region);
603
604 // Remove from the reclaim candidate set. Also remove from the
605 // collection set so that later encounters avoid the slow path.
606 inline void set_humongous_is_live(oop obj);
607
608 // Register the given region to be part of the collection set.
609 inline void register_humongous_region_with_cset(uint index);
610 // Register regions with humongous objects (actually on the start region) in
611 // the in_cset_fast_test table.
612 void register_humongous_regions_with_cset();
613 // We register a region with the fast "in collection set" test. We
614 // simply set to true the array slot corresponding to this region.
615 void register_young_region_with_cset(HeapRegion* r) {
616 _in_cset_fast_test.set_in_young(r->hrm_index());
617 }
618 void register_old_region_with_cset(HeapRegion* r) {
619 _in_cset_fast_test.set_in_old(r->hrm_index());
620 }
621 inline void register_ext_region_with_cset(HeapRegion* r) {
622 _in_cset_fast_test.set_ext(r->hrm_index());
623 }
624 void clear_in_cset(const HeapRegion* hr) {
625 _in_cset_fast_test.clear(hr);
626 }
627
628 void clear_cset_fast_test() {
629 _in_cset_fast_test.clear();
630 }
631
632 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause);
633
634 // This is called at the start of either a concurrent cycle or a Full
635 // GC to update the number of old marking cycles started.
636 void increment_old_marking_cycles_started();
637
638 // This is called at the end of either a concurrent cycle or a Full
639 // GC to update the number of old marking cycles completed. Those two
640 // can happen in a nested fashion, i.e., we start a concurrent
641 // cycle, a Full GC happens half-way through it which ends first,
642 // and then the cycle notices that a Full GC happened and ends
643 // too. The concurrent parameter is a boolean to help us do a bit
644 // tighter consistency checking in the method. If concurrent is
645 // false, the caller is the inner caller in the nesting (i.e., the
646 // Full GC). If concurrent is true, the caller is the outer caller
647 // in this nesting (i.e., the concurrent cycle). Further nesting is
648 // not currently supported. The end of this call also notifies
649 // the FullGCCount_lock in case a Java thread is waiting for a full
650 // GC to happen (e.g., it called System.gc() with
651 // +ExplicitGCInvokesConcurrent).
652 void increment_old_marking_cycles_completed(bool concurrent);
653
654 uint old_marking_cycles_completed() {
655 return _old_marking_cycles_completed;
656 }
657
658 G1HRPrinter* hr_printer() { return &_hr_printer; }
659
660 // Allocates a new heap region instance.
661 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr);
662
663 // Allocate the highest free region in the reserved heap. This will commit
664 // regions as necessary.
665 HeapRegion* alloc_highest_free_region();
666
667 // Frees a non-humongous region by initializing its contents and
668 // adding it to the free list that's passed as a parameter (this is
669 // usually a local list which will be appended to the master free
670 // list later). The used bytes of freed regions are accumulated in
671 // pre_used. If skip_remset is true, the region's RSet will not be freed
672 // up. If skip_hot_card_cache is true, the region's hot card cache will not
673 // be freed up. The assumption is that this will be done later.
674 // The locked parameter indicates if the caller has already taken
675 // care of proper synchronization. This may allow some optimizations.
676 void free_region(HeapRegion* hr,
677 FreeRegionList* free_list,
678 bool skip_remset,
679 bool skip_hot_card_cache = false,
680 bool locked = false);
681
682 // It dirties the cards that cover the block so that the post
683 // write barrier never queues anything when updating objects on this
684 // block. It is assumed (and in fact we assert) that the block
685 // belongs to a young region.
686 inline void dirty_young_block(HeapWord* start, size_t word_size);
687
688 // Frees a humongous region by collapsing it into individual regions
689 // and calling free_region() for each of them. The freed regions
690 // will be added to the free list that's passed as a parameter (this
691 // is usually a local list which will be appended to the master free
692 // list later). The used bytes of freed regions are accumulated in
693 // pre_used. If skip_remset is true, the region's RSet will not be freed
694 // up. The assumption is that this will be done later.
695 void free_humongous_region(HeapRegion* hr,
696 FreeRegionList* free_list,
697 bool skip_remset);
698
699 // Facility for allocating in 'archive' regions in high heap memory and
700 // recording the allocated ranges. These should all be called from the
701 // VM thread at safepoints, without the heap lock held. They can be used
702 // to create and archive a set of heap regions which can be mapped at the
703 // same fixed addresses in a subsequent JVM invocation.
704 void begin_archive_alloc_range(bool open = false);
705
706 // Check if the requested size would be too large for an archive allocation.
707 bool is_archive_alloc_too_large(size_t word_size);
708
709 // Allocate memory of the requested size from the archive region. This will
710 // return NULL if the size is too large or if no memory is available. It
711 // does not trigger a garbage collection.
712 HeapWord* archive_mem_allocate(size_t word_size);
713
714 // Optionally aligns the end address and returns the allocated ranges in
715 // an array of MemRegions in order of ascending addresses.
716 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
717 size_t end_alignment_in_bytes = 0);
718
719 // Facility for allocating a fixed range within the heap and marking
720 // the containing regions as 'archive'. For use at JVM init time, when the
721 // caller may mmap archived heap data at the specified range(s).
722 // Verify that the MemRegions specified in the argument array are within the
723 // reserved heap.
724 bool check_archive_addresses(MemRegion* range, size_t count);
725
726 // Commit the appropriate G1 regions containing the specified MemRegions
727 // and mark them as 'archive' regions. The regions in the array must be
728 // non-overlapping and in order of ascending address.
729 bool alloc_archive_regions(MemRegion* range, size_t count, bool open);
730
731 // Insert any required filler objects in the G1 regions around the specified
732 // ranges to make the regions parseable. This must be called after
733 // alloc_archive_regions, and after class loading has occurred.
734 void fill_archive_regions(MemRegion* range, size_t count);
735
736 // For each of the specified MemRegions, uncommit the containing G1 regions
737 // which had been allocated by alloc_archive_regions. This should be called
738 // rather than fill_archive_regions at JVM init time if the archive file
739 // mapping failed, with the same non-overlapping and sorted MemRegion array.
740 void dealloc_archive_regions(MemRegion* range, size_t count);
741
742 protected:
743
744 // Shrink the garbage-first heap by at most the given size (in bytes!).
745 // (Rounds down to a HeapRegion boundary.)
746 virtual void shrink(size_t expand_bytes);
747 void shrink_helper(size_t expand_bytes);
748
749 #if TASKQUEUE_STATS
750 static void print_taskqueue_stats_hdr(outputStream* const st);
751 void print_taskqueue_stats() const;
752 void reset_taskqueue_stats();
753 #endif // TASKQUEUE_STATS
754
755 // Schedule the VM operation that will do an evacuation pause to
756 // satisfy an allocation request of word_size. *succeeded will
757 // return whether the VM operation was successful (it did do an
758 // evacuation pause) or not (another thread beat us to it or the GC
759 // locker was active). Given that we should not be holding the
760 // Heap_lock when we enter this method, we will pass the
761 // gc_count_before (i.e., total_collections()) as a parameter since
762 // it has to be read while holding the Heap_lock. Currently, both
763 // methods that call do_collection_pause() release the Heap_lock
764 // before the call, so it's easy to read gc_count_before just before.
765 HeapWord* do_collection_pause(size_t word_size,
766 uint gc_count_before,
767 bool* succeeded,
768 GCCause::Cause gc_cause);
769
770 void wait_for_root_region_scanning();
771
772 // The guts of the incremental collection pause, executed by the vm
773 // thread. It returns false if it is unable to do the collection due
774 // to the GC locker being active, true otherwise
775 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
776
777 // Actually do the work of evacuating the collection set.
778 virtual void evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states);
779
780 void pre_evacuate_collection_set();
781 void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss);
782
783 // Print the header for the per-thread termination statistics.
784 static void print_termination_stats_hdr();
785 // Print actual per-thread termination statistics.
786 void print_termination_stats(uint worker_id,
787 double elapsed_ms,
788 double strong_roots_ms,
789 double term_ms,
790 size_t term_attempts,
791 size_t alloc_buffer_waste,
792 size_t undo_waste) const;
793 // Update object copying statistics.
794 void record_obj_copy_mem_stats();
795
796 // The hot card cache for remembered set insertion optimization.
797 G1HotCardCache* _hot_card_cache;
798
799 // The g1 remembered set of the heap.
800 G1RemSet* _g1_rem_set;
801
802 // A set of cards that cover the objects for which the Rsets should be updated
803 // concurrently after the collection.
804 DirtyCardQueueSet _dirty_card_queue_set;
805
806 // After a collection pause, convert the regions in the collection set into free
807 // regions.
808 void free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words);
809
810 // Abandon the current collection set without recording policy
811 // statistics or updating free lists.
812 void abandon_collection_set(G1CollectionSet* collection_set);
813
814 // The concurrent marker (and the thread it runs in.)
815 G1ConcurrentMark* _cm;
816 ConcurrentMarkThread* _cmThread;
817
818 // The concurrent refiner.
819 G1ConcurrentRefine* _cr;
820
821 // The parallel task queues
822 RefToScanQueueSet *_task_queues;
823
824 // True iff a evacuation has failed in the current collection.
825 bool _evacuation_failed;
826
827 EvacuationFailedInfo* _evacuation_failed_info_array;
828
829 // Failed evacuations cause some logical from-space objects to have
830 // forwarding pointers to themselves. Reset them.
831 void remove_self_forwarding_pointers();
832
833 // Restore the objects in the regions in the collection set after an
834 // evacuation failure.
835 void restore_after_evac_failure();
836
837 PreservedMarksSet _preserved_marks_set;
838
839 // Preserve the mark of "obj", if necessary, in preparation for its mark
840 // word being overwritten with a self-forwarding-pointer.
841 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m);
842
843 #ifndef PRODUCT
844 // Support for forcing evacuation failures. Analogous to
845 // PromotionFailureALot for the other collectors.
846
847 // Records whether G1EvacuationFailureALot should be in effect
848 // for the current GC
849 bool _evacuation_failure_alot_for_current_gc;
850
851 // Used to record the GC number for interval checking when
852 // determining whether G1EvaucationFailureALot is in effect
853 // for the current GC.
854 size_t _evacuation_failure_alot_gc_number;
855
856 // Count of the number of evacuations between failures.
857 volatile size_t _evacuation_failure_alot_count;
858
859 // Set whether G1EvacuationFailureALot should be in effect
860 // for the current GC (based upon the type of GC and which
861 // command line flags are set);
862 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young,
863 bool during_initial_mark,
864 bool during_marking);
865
866 inline void set_evacuation_failure_alot_for_current_gc();
867
868 // Return true if it's time to cause an evacuation failure.
869 inline bool evacuation_should_fail();
870
871 // Reset the G1EvacuationFailureALot counters. Should be called at
872 // the end of an evacuation pause in which an evacuation failure occurred.
873 inline void reset_evacuation_should_fail();
874 #endif // !PRODUCT
875
876 // ("Weak") Reference processing support.
877 //
878 // G1 has 2 instances of the reference processor class. One
879 // (_ref_processor_cm) handles reference object discovery
880 // and subsequent processing during concurrent marking cycles.
881 //
882 // The other (_ref_processor_stw) handles reference object
883 // discovery and processing during full GCs and incremental
884 // evacuation pauses.
885 //
886 // During an incremental pause, reference discovery will be
887 // temporarily disabled for _ref_processor_cm and will be
888 // enabled for _ref_processor_stw. At the end of the evacuation
889 // pause references discovered by _ref_processor_stw will be
890 // processed and discovery will be disabled. The previous
891 // setting for reference object discovery for _ref_processor_cm
892 // will be re-instated.
893 //
894 // At the start of marking:
895 // * Discovery by the CM ref processor is verified to be inactive
896 // and it's discovered lists are empty.
897 // * Discovery by the CM ref processor is then enabled.
898 //
899 // At the end of marking:
900 // * Any references on the CM ref processor's discovered
901 // lists are processed (possibly MT).
902 //
903 // At the start of full GC we:
904 // * Disable discovery by the CM ref processor and
905 // empty CM ref processor's discovered lists
906 // (without processing any entries).
907 // * Verify that the STW ref processor is inactive and it's
908 // discovered lists are empty.
909 // * Temporarily set STW ref processor discovery as single threaded.
910 // * Temporarily clear the STW ref processor's _is_alive_non_header
911 // field.
912 // * Finally enable discovery by the STW ref processor.
913 //
914 // The STW ref processor is used to record any discovered
915 // references during the full GC.
916 //
917 // At the end of a full GC we:
918 // * Enqueue any reference objects discovered by the STW ref processor
919 // that have non-live referents. This has the side-effect of
920 // making the STW ref processor inactive by disabling discovery.
921 // * Verify that the CM ref processor is still inactive
922 // and no references have been placed on it's discovered
923 // lists (also checked as a precondition during initial marking).
924
925 // The (stw) reference processor...
926 ReferenceProcessor* _ref_processor_stw;
927
928 // During reference object discovery, the _is_alive_non_header
929 // closure (if non-null) is applied to the referent object to
930 // determine whether the referent is live. If so then the
931 // reference object does not need to be 'discovered' and can
932 // be treated as a regular oop. This has the benefit of reducing
933 // the number of 'discovered' reference objects that need to
934 // be processed.
935 //
936 // Instance of the is_alive closure for embedding into the
937 // STW reference processor as the _is_alive_non_header field.
938 // Supplying a value for the _is_alive_non_header field is
939 // optional but doing so prevents unnecessary additions to
940 // the discovered lists during reference discovery.
941 G1STWIsAliveClosure _is_alive_closure_stw;
942
943 // The (concurrent marking) reference processor...
944 ReferenceProcessor* _ref_processor_cm;
945
946 // Instance of the concurrent mark is_alive closure for embedding
947 // into the Concurrent Marking reference processor as the
948 // _is_alive_non_header field. Supplying a value for the
949 // _is_alive_non_header field is optional but doing so prevents
950 // unnecessary additions to the discovered lists during reference
951 // discovery.
952 G1CMIsAliveClosure _is_alive_closure_cm;
953
954 volatile bool _free_regions_coming;
955
956 public:
957
958 RefToScanQueue *task_queue(uint i) const;
959
960 uint num_task_queues() const;
961
962 // A set of cards where updates happened during the GC
963 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
964
965 // Create a G1CollectedHeap with the specified policy.
966 // Must call the initialize method afterwards.
967 // May not return if something goes wrong.
968 G1CollectedHeap(G1CollectorPolicy* policy);
969
970 private:
971 jint initialize_concurrent_refinement();
972 jint initialize_young_gen_sampling_thread();
973 public:
974 // Initialize the G1CollectedHeap to have the initial and
975 // maximum sizes and remembered and barrier sets
976 // specified by the policy object.
977 jint initialize();
978
979 virtual void stop();
980 virtual void safepoint_synchronize_begin();
981 virtual void safepoint_synchronize_end();
982
983 // Return the (conservative) maximum heap alignment for any G1 heap
984 static size_t conservative_max_heap_alignment();
985
986 // Does operations required after initialization has been done.
987 void post_initialize();
988
989 // Initialize weak reference processing.
990 void ref_processing_init();
991
992 virtual Name kind() const {
993 return CollectedHeap::G1CollectedHeap;
994 }
995
996 virtual const char* name() const {
997 return "G1";
998 }
999
1000 const G1CollectorState* collector_state() const { return &_collector_state; }
1001 G1CollectorState* collector_state() { return &_collector_state; }
1002
1003 // The current policy object for the collector.
1004 G1Policy* g1_policy() const { return _g1_policy; }
1005
1006 const G1CollectionSet* collection_set() const { return &_collection_set; }
1007 G1CollectionSet* collection_set() { return &_collection_set; }
1008
1009 virtual CollectorPolicy* collector_policy() const;
1010
1011 // Adaptive size policy. No such thing for g1.
1012 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
1013
1014 virtual GrowableArray<MemoryManager*> memory_managers();
1015 virtual GrowableArray<MemoryPool*> memory_pools();
1016
1017 GCMemoryManager* minor_mgr();
1018 GCMemoryManager* major_mgr();
1019
1020 // The rem set and barrier set.
1021 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
1022
1023 // Try to minimize the remembered set.
1024 void scrub_rem_set();
1025
1026 uint get_gc_time_stamp() {
1027 return _gc_time_stamp;
1028 }
1029
1030 inline void reset_gc_time_stamp();
1031
1032 void check_gc_time_stamps() PRODUCT_RETURN;
1033
1034 inline void increment_gc_time_stamp();
1035
1036 // Reset the given region's GC timestamp. If it's starts humongous,
1037 // also reset the GC timestamp of its corresponding
1038 // continues humongous regions too.
1039 void reset_gc_time_stamps(HeapRegion* hr);
1040
1041 // Apply the given closure on all cards in the Hot Card Cache, emptying it.
1042 void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i);
1043
1044 // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it.
1045 void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i);
1046
1047 // The shared block offset table array.
1048 G1BlockOffsetTable* bot() const { return _bot; }
1049
1050 // Reference Processing accessors
1051
1052 // The STW reference processor....
1053 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1054
1055 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; }
1056
1057 // The Concurrent Marking reference processor...
1058 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1059
1060 size_t unused_committed_regions_in_bytes() const;
1061 virtual size_t capacity() const;
1062 virtual size_t used() const;
1063 // This should be called when we're not holding the heap lock. The
1064 // result might be a bit inaccurate.
1065 size_t used_unlocked() const;
1066 size_t recalculate_used() const;
1067
1068 // These virtual functions do the actual allocation.
1069 // Some heaps may offer a contiguous region for shared non-blocking
1070 // allocation, via inlined code (by exporting the address of the top and
1071 // end fields defining the extent of the contiguous allocation region.)
1072 // But G1CollectedHeap doesn't yet support this.
1073
1074 virtual bool is_maximal_no_gc() const {
1075 return _hrm.available() == 0;
1076 }
1077
1078 // The current number of regions in the heap.
1079 uint num_regions() const { return _hrm.length(); }
1080
1081 // The max number of regions in the heap.
1082 uint max_regions() const { return _hrm.max_length(); }
1083
1084 // The number of regions that are completely free.
1085 uint num_free_regions() const { return _hrm.num_free_regions(); }
1086
1087 MemoryUsage get_auxiliary_data_memory_usage() const {
1088 return _hrm.get_auxiliary_data_memory_usage();
1089 }
1090
1091 // The number of regions that are not completely free.
1092 uint num_used_regions() const { return num_regions() - num_free_regions(); }
1093
1094 #ifdef ASSERT
1095 bool is_on_master_free_list(HeapRegion* hr) {
1096 return _hrm.is_free(hr);
1097 }
1098 #endif // ASSERT
1099
1100 // Wrapper for the region list operations that can be called from
1101 // methods outside this class.
1102
1103 void secondary_free_list_add(FreeRegionList* list) {
1104 _secondary_free_list.add_ordered(list);
1105 }
1106
1107 void append_secondary_free_list() {
1108 _hrm.insert_list_into_free_list(&_secondary_free_list);
1109 }
1110
1111 void append_secondary_free_list_if_not_empty_with_lock() {
1112 // If the secondary free list looks empty there's no reason to
1113 // take the lock and then try to append it.
1114 if (!_secondary_free_list.is_empty()) {
1115 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1116 append_secondary_free_list();
1117 }
1118 }
1119
1120 inline void old_set_add(HeapRegion* hr);
1121 inline void old_set_remove(HeapRegion* hr);
1122
1123 size_t non_young_capacity_bytes() {
1124 return (_old_set.length() + _humongous_set.length()) * HeapRegion::GrainBytes;
1125 }
1126
1127 void set_free_regions_coming();
1128 void reset_free_regions_coming();
1129 bool free_regions_coming() { return _free_regions_coming; }
1130 void wait_while_free_regions_coming();
1131
1132 // Determine whether the given region is one that we are using as an
1133 // old GC alloc region.
1134 bool is_old_gc_alloc_region(HeapRegion* hr);
1135
1136 // Perform a collection of the heap; intended for use in implementing
1137 // "System.gc". This probably implies as full a collection as the
1138 // "CollectedHeap" supports.
1139 virtual void collect(GCCause::Cause cause);
1140
1141 virtual bool copy_allocation_context_stats(const jint* contexts,
1142 jlong* totals,
1143 jbyte* accuracy,
1144 jint len);
1145
1146 // True iff an evacuation has failed in the most-recent collection.
1147 bool evacuation_failed() { return _evacuation_failed; }
1148
1149 void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed);
1150 void prepend_to_freelist(FreeRegionList* list);
1151 void decrement_summary_bytes(size_t bytes);
1152
1153 virtual bool is_in(const void* p) const;
1154 #ifdef ASSERT
1155 // Returns whether p is in one of the available areas of the heap. Slow but
1156 // extensive version.
1157 bool is_in_exact(const void* p) const;
1158 #endif
1159
1160 // Return "TRUE" iff the given object address is within the collection
1161 // set. Assumes that the reference points into the heap.
1162 inline bool is_in_cset(const HeapRegion *hr);
1163 inline bool is_in_cset(oop obj);
1164 inline bool is_in_cset(HeapWord* addr);
1165
1166 inline bool is_in_cset_or_humongous(const oop obj);
1167
1168 private:
1169 // This array is used for a quick test on whether a reference points into
1170 // the collection set or not. Each of the array's elements denotes whether the
1171 // corresponding region is in the collection set or not.
1172 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test;
1173
1174 public:
1175
1176 inline InCSetState in_cset_state(const oop obj);
1177
1178 // Return "TRUE" iff the given object address is in the reserved
1179 // region of g1.
1180 bool is_in_g1_reserved(const void* p) const {
1181 return _hrm.reserved().contains(p);
1182 }
1183
1184 // Returns a MemRegion that corresponds to the space that has been
1185 // reserved for the heap
1186 MemRegion g1_reserved() const {
1187 return _hrm.reserved();
1188 }
1189
1190 virtual bool is_in_closed_subset(const void* p) const;
1191
1192 G1SATBCardTableLoggingModRefBS* g1_barrier_set() {
1193 return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set());
1194 }
1195
1196 G1HotCardCache* g1_hot_card_cache() const { return _hot_card_cache; }
1197
1198 // Iteration functions.
1199
1200 // Iterate over all objects, calling "cl.do_object" on each.
1201 virtual void object_iterate(ObjectClosure* cl);
1202
1203 virtual void safe_object_iterate(ObjectClosure* cl) {
1204 object_iterate(cl);
1205 }
1206
1207 // Iterate over heap regions, in address order, terminating the
1208 // iteration early if the "doHeapRegion" method returns "true".
1209 void heap_region_iterate(HeapRegionClosure* blk) const;
1210
1211 // Return the region with the given index. It assumes the index is valid.
1212 inline HeapRegion* region_at(uint index) const;
1213
1214 // Return the next region (by index) that is part of the same
1215 // humongous object that hr is part of.
1216 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const;
1217
1218 // Calculate the region index of the given address. Given address must be
1219 // within the heap.
1220 inline uint addr_to_region(HeapWord* addr) const;
1221
1222 inline HeapWord* bottom_addr_for_region(uint index) const;
1223
1224 // Two functions to iterate over the heap regions in parallel. Threads
1225 // compete using the HeapRegionClaimer to claim the regions before
1226 // applying the closure on them.
1227 // The _from_worker_offset version uses the HeapRegionClaimer and
1228 // the worker id to calculate a start offset to prevent all workers to
1229 // start from the point.
1230 void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
1231 HeapRegionClaimer* hrclaimer,
1232 uint worker_id) const;
1233
1234 void heap_region_par_iterate_from_start(HeapRegionClosure* cl,
1235 HeapRegionClaimer* hrclaimer) const;
1236
1237 // Iterate over the regions (if any) in the current collection set.
1238 void collection_set_iterate(HeapRegionClosure* blk);
1239
1240 // Iterate over the regions (if any) in the current collection set. Starts the
1241 // iteration over the entire collection set so that the start regions of a given
1242 // worker id over the set active_workers are evenly spread across the set of
1243 // collection set regions.
1244 void collection_set_iterate_from(HeapRegionClosure *blk, uint worker_id);
1245
1246 // Returns the HeapRegion that contains addr. addr must not be NULL.
1247 template <class T>
1248 inline HeapRegion* heap_region_containing(const T addr) const;
1249
1250 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1251 // each address in the (reserved) heap is a member of exactly
1252 // one block. The defining characteristic of a block is that it is
1253 // possible to find its size, and thus to progress forward to the next
1254 // block. (Blocks may be of different sizes.) Thus, blocks may
1255 // represent Java objects, or they might be free blocks in a
1256 // free-list-based heap (or subheap), as long as the two kinds are
1257 // distinguishable and the size of each is determinable.
1258
1259 // Returns the address of the start of the "block" that contains the
1260 // address "addr". We say "blocks" instead of "object" since some heaps
1261 // may not pack objects densely; a chunk may either be an object or a
1262 // non-object.
1263 virtual HeapWord* block_start(const void* addr) const;
1264
1265 // Requires "addr" to be the start of a chunk, and returns its size.
1266 // "addr + size" is required to be the start of a new chunk, or the end
1267 // of the active area of the heap.
1268 virtual size_t block_size(const HeapWord* addr) const;
1269
1270 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1271 // the block is an object.
1272 virtual bool block_is_obj(const HeapWord* addr) const;
1273
1274 // Section on thread-local allocation buffers (TLABs)
1275 // See CollectedHeap for semantics.
1276
1277 bool supports_tlab_allocation() const;
1278 size_t tlab_capacity(Thread* ignored) const;
1279 size_t tlab_used(Thread* ignored) const;
1280 size_t max_tlab_size() const;
1281 size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1282
1283 // Can a compiler initialize a new object without store barriers?
1284 // This permission only extends from the creation of a new object
1285 // via a TLAB up to the first subsequent safepoint. If such permission
1286 // is granted for this heap type, the compiler promises to call
1287 // defer_store_barrier() below on any slow path allocation of
1288 // a new object for which such initializing store barriers will
1289 // have been elided. G1, like CMS, allows this, but should be
1290 // ready to provide a compensating write barrier as necessary
1291 // if that storage came out of a non-young region. The efficiency
1292 // of this implementation depends crucially on being able to
1293 // answer very efficiently in constant time whether a piece of
1294 // storage in the heap comes from a young region or not.
1295 // See ReduceInitialCardMarks.
1296 virtual bool can_elide_tlab_store_barriers() const {
1297 return true;
1298 }
1299
1300 virtual bool card_mark_must_follow_store() const {
1301 return true;
1302 }
1303
1304 inline bool is_in_young(const oop obj);
1305
1306 // We don't need barriers for initializing stores to objects
1307 // in the young gen: for the SATB pre-barrier, there is no
1308 // pre-value that needs to be remembered; for the remembered-set
1309 // update logging post-barrier, we don't maintain remembered set
1310 // information for young gen objects.
1311 virtual inline bool can_elide_initializing_store_barrier(oop new_obj);
1312
1313 // Returns "true" iff the given word_size is "very large".
1314 static bool is_humongous(size_t word_size) {
1315 // Note this has to be strictly greater-than as the TLABs
1316 // are capped at the humongous threshold and we want to
1317 // ensure that we don't try to allocate a TLAB as
1318 // humongous and that we don't allocate a humongous
1319 // object in a TLAB.
1320 return word_size > _humongous_object_threshold_in_words;
1321 }
1322
1323 // Returns the humongous threshold for a specific region size
1324 static size_t humongous_threshold_for(size_t region_size) {
1325 return (region_size / 2);
1326 }
1327
1328 // Returns the number of regions the humongous object of the given word size
1329 // requires.
1330 static size_t humongous_obj_size_in_regions(size_t word_size);
1331
1332 // Print the maximum heap capacity.
1333 virtual size_t max_capacity() const;
1334
1335 virtual jlong millis_since_last_gc();
1336
1337
1338 // Convenience function to be used in situations where the heap type can be
1339 // asserted to be this type.
1340 static G1CollectedHeap* heap();
1341
1342 void set_region_short_lived_locked(HeapRegion* hr);
1343 // add appropriate methods for any other surv rate groups
1344
1345 const G1SurvivorRegions* survivor() const { return &_survivor; }
1346
1347 uint survivor_regions_count() const {
1348 return _survivor.length();
1349 }
1350
1351 uint eden_regions_count() const {
1352 return _eden.length();
1353 }
1354
1355 uint young_regions_count() const {
1356 return _eden.length() + _survivor.length();
1357 }
1358
1359 uint old_regions_count() const { return _old_set.length(); }
1360
1361 uint humongous_regions_count() const { return _humongous_set.length(); }
1362
1363 #ifdef ASSERT
1364 bool check_young_list_empty();
1365 #endif
1366
1367 // *** Stuff related to concurrent marking. It's not clear to me that so
1368 // many of these need to be public.
1369
1370 // The functions below are helper functions that a subclass of
1371 // "CollectedHeap" can use in the implementation of its virtual
1372 // functions.
1373 // This performs a concurrent marking of the live objects in a
1374 // bitmap off to the side.
1375 void doConcurrentMark();
1376
1377 bool isMarkedNext(oop obj) const;
1378
1379 // Determine if an object is dead, given the object and also
1380 // the region to which the object belongs. An object is dead
1381 // iff a) it was not allocated since the last mark, b) it
1382 // is not marked, and c) it is not in an archive region.
1383 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1384 return
1385 hr->is_obj_dead(obj, _cm->prev_mark_bitmap()) &&
1386 !hr->is_archive();
1387 }
1388
1389 // This function returns true when an object has been
1390 // around since the previous marking and hasn't yet
1391 // been marked during this marking, and is not in an archive region.
1392 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1393 return
1394 !hr->obj_allocated_since_next_marking(obj) &&
1395 !isMarkedNext(obj) &&
1396 !hr->is_archive();
1397 }
1398
1399 // Determine if an object is dead, given only the object itself.
1400 // This will find the region to which the object belongs and
1401 // then call the region version of the same function.
1402
1403 // Added if it is NULL it isn't dead.
1404
1405 inline bool is_obj_dead(const oop obj) const;
1406
1407 inline bool is_obj_ill(const oop obj) const;
1408
1409 inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const;
1410 inline bool is_obj_dead_full(const oop obj) const;
1411
1412 G1ConcurrentMark* concurrent_mark() const { return _cm; }
1413
1414 // Refinement
1415
1416 G1ConcurrentRefine* concurrent_refine() const { return _cr; }
1417
1418 // Optimized nmethod scanning support routines
1419
1420 // Is an oop scavengeable
1421 virtual bool is_scavengable(oop obj);
1422
1423 // Register the given nmethod with the G1 heap.
1424 virtual void register_nmethod(nmethod* nm);
1425
1426 // Unregister the given nmethod from the G1 heap.
1427 virtual void unregister_nmethod(nmethod* nm);
1428
1429 // Free up superfluous code root memory.
1430 void purge_code_root_memory();
1431
1432 // Rebuild the strong code root lists for each region
1433 // after a full GC.
1434 void rebuild_strong_code_roots();
1435
1436 // Partial cleaning used when class unloading is disabled.
1437 // Let the caller choose what structures to clean out:
1438 // - StringTable
1439 // - SymbolTable
1440 // - StringDeduplication structures
1441 void partial_cleaning(BoolObjectClosure* is_alive, bool unlink_strings, bool unlink_symbols, bool unlink_string_dedup);
1442
1443 // Complete cleaning used when class unloading is enabled.
1444 // Cleans out all structures handled by partial_cleaning and also the CodeCache.
1445 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred);
1446
1447 // Redirty logged cards in the refinement queue.
1448 void redirty_logged_cards();
1449 // Verification
1450
1451 // Perform any cleanup actions necessary before allowing a verification.
1452 virtual void prepare_for_verify();
1453
1454 // Perform verification.
1455
1456 // vo == UsePrevMarking -> use "prev" marking information,
1457 // vo == UseNextMarking -> use "next" marking information
1458 // vo == UseFullMarking -> use "next" marking bitmap but no TAMS
1459 //
1460 // NOTE: Only the "prev" marking information is guaranteed to be
1461 // consistent most of the time, so most calls to this should use
1462 // vo == UsePrevMarking.
1463 // Currently, there is only one case where this is called with
1464 // vo == UseNextMarking, which is to verify the "next" marking
1465 // information at the end of remark.
1466 // Currently there is only one place where this is called with
1467 // vo == UseFullMarking, which is to verify the marking during a
1468 // full GC.
1469 void verify(VerifyOption vo);
1470
1471 // WhiteBox testing support.
1472 virtual bool supports_concurrent_phase_control() const;
1473 virtual const char* const* concurrent_phases() const;
1474 virtual bool request_concurrent_phase(const char* phase);
1475
1476 // The methods below are here for convenience and dispatch the
1477 // appropriate method depending on value of the given VerifyOption
1478 // parameter. The values for that parameter, and their meanings,
1479 // are the same as those above.
1480
1481 bool is_obj_dead_cond(const oop obj,
1482 const HeapRegion* hr,
1483 const VerifyOption vo) const;
1484
1485 bool is_obj_dead_cond(const oop obj,
1486 const VerifyOption vo) const;
1487
1488 G1HeapSummary create_g1_heap_summary();
1489 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats);
1490
1491 // Printing
1492 private:
1493 void print_heap_regions() const;
1494 void print_regions_on(outputStream* st) const;
1495
1496 public:
1497 virtual void print_on(outputStream* st) const;
1498 virtual void print_extended_on(outputStream* st) const;
1499 virtual void print_on_error(outputStream* st) const;
1500
1501 virtual void print_gc_threads_on(outputStream* st) const;
1502 virtual void gc_threads_do(ThreadClosure* tc) const;
1503
1504 // Override
1505 void print_tracing_info() const;
1506
1507 // The following two methods are helpful for debugging RSet issues.
1508 void print_cset_rsets() PRODUCT_RETURN;
1509 void print_all_rsets() PRODUCT_RETURN;
1510
1511 public:
1512 size_t pending_card_num();
1513
1514 protected:
1515 size_t _max_heap_capacity;
1516 };
1517
1518 class G1ParEvacuateFollowersClosure : public VoidClosure {
1519 private:
1520 double _start_term;
1521 double _term_time;
1522 size_t _term_attempts;
1523
1524 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
1525 void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
1526 protected:
1527 G1CollectedHeap* _g1h;
1528 G1ParScanThreadState* _par_scan_state;
1529 RefToScanQueueSet* _queues;
1530 ParallelTaskTerminator* _terminator;
1531
1532 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
1533 RefToScanQueueSet* queues() { return _queues; }
1534 ParallelTaskTerminator* terminator() { return _terminator; }
1535
1536 public:
1537 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
1538 G1ParScanThreadState* par_scan_state,
1539 RefToScanQueueSet* queues,
1540 ParallelTaskTerminator* terminator)
1541 : _g1h(g1h), _par_scan_state(par_scan_state),
1542 _queues(queues), _terminator(terminator),
1543 _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
1544
1545 void do_void();
1546
1547 double term_time() const { return _term_time; }
1548 size_t term_attempts() const { return _term_attempts; }
1549
1550 private:
1551 inline bool offer_termination();
1552 };
1553
1554 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP