rev 11970 : imported patch 8157952-parallelize-memory-pretouch
1 /*
2 * Copyright (c) 2001, 2016, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
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24
25 #ifndef SHARE_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/g1HeapVerifier.hpp"
38 #include "gc/g1/g1HRPrinter.hpp"
39 #include "gc/g1/g1InCSetState.hpp"
40 #include "gc/g1/g1MonitoringSupport.hpp"
41 #include "gc/g1/g1SATBCardTableModRefBS.hpp"
42 #include "gc/g1/g1SurvivorRegions.hpp"
43 #include "gc/g1/g1YCTypes.hpp"
44 #include "gc/g1/hSpaceCounters.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/plab.hpp"
50 #include "gc/shared/preservedMarks.hpp"
51 #include "memory/memRegion.hpp"
52 #include "utilities/stack.hpp"
53
54 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
55 // It uses the "Garbage First" heap organization and algorithm, which
56 // may combine concurrent marking with parallel, incremental compaction of
57 // heap subsets that will yield large amounts of garbage.
58
59 // Forward declarations
60 class HeapRegion;
61 class HRRSCleanupTask;
62 class GenerationSpec;
63 class OopsInHeapRegionClosure;
64 class G1ParScanThreadState;
65 class G1ParScanThreadStateSet;
66 class G1KlassScanClosure;
67 class G1ParScanThreadState;
68 class ObjectClosure;
69 class SpaceClosure;
70 class CompactibleSpaceClosure;
71 class Space;
72 class G1CollectionSet;
73 class G1CollectorPolicy;
74 class G1Policy;
75 class G1HotCardCache;
76 class G1RemSet;
77 class HeapRegionRemSetIterator;
78 class G1ConcurrentMark;
79 class ConcurrentMarkThread;
80 class ConcurrentG1Refine;
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 G1HeapVerifier;
91 class G1HeapSizingPolicy;
92
93 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue;
94 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
95
96 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
97 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
98
99 // The G1 STW is alive closure.
100 // An instance is embedded into the G1CH and used as the
101 // (optional) _is_alive_non_header closure in the STW
102 // reference processor. It is also extensively used during
103 // reference processing during STW evacuation pauses.
104 class G1STWIsAliveClosure: public BoolObjectClosure {
105 G1CollectedHeap* _g1;
106 public:
107 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
108 bool do_object_b(oop p);
109 };
110
111 class RefineCardTableEntryClosure;
112
113 class G1RegionMappingChangedListener : public G1MappingChangedListener {
114 private:
115 void reset_from_card_cache(uint start_idx, size_t num_regions);
116 public:
117 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
118 };
119
120 class G1CollectedHeap : public CollectedHeap {
121 friend class G1FreeCollectionSetTask;
122 friend class VM_CollectForMetadataAllocation;
123 friend class VM_G1CollectForAllocation;
124 friend class VM_G1CollectFull;
125 friend class VM_G1IncCollectionPause;
126 friend class VMStructs;
127 friend class MutatorAllocRegion;
128 friend class G1GCAllocRegion;
129 friend class G1HeapVerifier;
130
131 // Closures used in implementation.
132 friend class G1ParScanThreadState;
133 friend class G1ParScanThreadStateSet;
134 friend class G1ParTask;
135 friend class G1PLABAllocator;
136 friend class G1PrepareCompactClosure;
137
138 // Other related classes.
139 friend class HeapRegionClaimer;
140
141 // Testing classes.
142 friend class G1CheckCSetFastTableClosure;
143
144 private:
145 WorkGang* _workers;
146 G1CollectorPolicy* _collector_policy;
147
148 static size_t _humongous_object_threshold_in_words;
149
150 // The secondary free list which contains regions that have been
151 // freed up during the cleanup process. This will be appended to
152 // the master free list when appropriate.
153 FreeRegionList _secondary_free_list;
154
155 // It keeps track of the old regions.
156 HeapRegionSet _old_set;
157
158 // It keeps track of the humongous regions.
159 HeapRegionSet _humongous_set;
160
161 void eagerly_reclaim_humongous_regions();
162
163 // The number of regions we could create by expansion.
164 uint _expansion_regions;
165
166 // The block offset table for the G1 heap.
167 G1BlockOffsetTable* _bot;
168
169 // Tears down the region sets / lists so that they are empty and the
170 // regions on the heap do not belong to a region set / list. The
171 // only exception is the humongous set which we leave unaltered. If
172 // free_list_only is true, it will only tear down the master free
173 // list. It is called before a Full GC (free_list_only == false) or
174 // before heap shrinking (free_list_only == true).
175 void tear_down_region_sets(bool free_list_only);
176
177 // Rebuilds the region sets / lists so that they are repopulated to
178 // reflect the contents of the heap. The only exception is the
179 // humongous set which was not torn down in the first place. If
180 // free_list_only is true, it will only rebuild the master free
181 // list. It is called after a Full GC (free_list_only == false) or
182 // after heap shrinking (free_list_only == true).
183 void rebuild_region_sets(bool free_list_only);
184
185 // Callback for region mapping changed events.
186 G1RegionMappingChangedListener _listener;
187
188 // The sequence of all heap regions in the heap.
189 HeapRegionManager _hrm;
190
191 // Manages all allocations with regions except humongous object allocations.
192 G1Allocator* _allocator;
193
194 // Manages all heap verification.
195 G1HeapVerifier* _verifier;
196
197 // Outside of GC pauses, the number of bytes used in all regions other
198 // than the current allocation region(s).
199 size_t _summary_bytes_used;
200
201 void increase_used(size_t bytes);
202 void decrease_used(size_t bytes);
203
204 void set_used(size_t bytes);
205
206 // Class that handles archive allocation ranges.
207 G1ArchiveAllocator* _archive_allocator;
208
209 // Statistics for each allocation context
210 AllocationContextStats _allocation_context_stats;
211
212 // GC allocation statistics policy for survivors.
213 G1EvacStats _survivor_evac_stats;
214
215 // GC allocation statistics policy for tenured objects.
216 G1EvacStats _old_evac_stats;
217
218 // It specifies whether we should attempt to expand the heap after a
219 // region allocation failure. If heap expansion fails we set this to
220 // false so that we don't re-attempt the heap expansion (it's likely
221 // that subsequent expansion attempts will also fail if one fails).
222 // Currently, it is only consulted during GC and it's reset at the
223 // start of each GC.
224 bool _expand_heap_after_alloc_failure;
225
226 // Helper for monitoring and management support.
227 G1MonitoringSupport* _g1mm;
228
229 // Records whether the region at the given index is (still) a
230 // candidate for eager reclaim. Only valid for humongous start
231 // regions; other regions have unspecified values. Humongous start
232 // regions are initialized at start of collection pause, with
233 // candidates removed from the set as they are found reachable from
234 // roots or the young generation.
235 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> {
236 protected:
237 bool default_value() const { return false; }
238 public:
239 void clear() { G1BiasedMappedArray<bool>::clear(); }
240 void set_candidate(uint region, bool value) {
241 set_by_index(region, value);
242 }
243 bool is_candidate(uint region) {
244 return get_by_index(region);
245 }
246 };
247
248 HumongousReclaimCandidates _humongous_reclaim_candidates;
249 // Stores whether during humongous object registration we found candidate regions.
250 // If not, we can skip a few steps.
251 bool _has_humongous_reclaim_candidates;
252
253 volatile uint _gc_time_stamp;
254
255 G1HRPrinter _hr_printer;
256
257 // It decides whether an explicit GC should start a concurrent cycle
258 // instead of doing a STW GC. Currently, a concurrent cycle is
259 // explicitly started if:
260 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
261 // (b) cause == _g1_humongous_allocation
262 // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
263 // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent.
264 // (e) cause == _update_allocation_context_stats_inc
265 // (f) cause == _wb_conc_mark
266 bool should_do_concurrent_full_gc(GCCause::Cause cause);
267
268 // indicates whether we are in young or mixed GC mode
269 G1CollectorState _collector_state;
270
271 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
272 // concurrent cycles) we have started.
273 volatile uint _old_marking_cycles_started;
274
275 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
276 // concurrent cycles) we have completed.
277 volatile uint _old_marking_cycles_completed;
278
279 // This is a non-product method that is helpful for testing. It is
280 // called at the end of a GC and artificially expands the heap by
281 // allocating a number of dead regions. This way we can induce very
282 // frequent marking cycles and stress the cleanup / concurrent
283 // cleanup code more (as all the regions that will be allocated by
284 // this method will be found dead by the marking cycle).
285 void allocate_dummy_regions() PRODUCT_RETURN;
286
287 // Clear RSets after a compaction. It also resets the GC time stamps.
288 void clear_rsets_post_compaction();
289
290 // If the HR printer is active, dump the state of the regions in the
291 // heap after a compaction.
292 void print_hrm_post_compaction();
293
294 // Create a memory mapper for auxiliary data structures of the given size and
295 // translation factor.
296 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description,
297 size_t size,
298 size_t translation_factor);
299
300 static G1Policy* create_g1_policy();
301
302 void trace_heap(GCWhen::Type when, const GCTracer* tracer);
303
304 void process_weak_jni_handles();
305
306 // These are macros so that, if the assert fires, we get the correct
307 // line number, file, etc.
308
309 #define heap_locking_asserts_params(_extra_message_) \
310 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
311 (_extra_message_), \
312 BOOL_TO_STR(Heap_lock->owned_by_self()), \
313 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
314 BOOL_TO_STR(Thread::current()->is_VM_thread())
315
316 #define assert_heap_locked() \
317 do { \
318 assert(Heap_lock->owned_by_self(), \
319 heap_locking_asserts_params("should be holding the Heap_lock")); \
320 } while (0)
321
322 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
323 do { \
324 assert(Heap_lock->owned_by_self() || \
325 (SafepointSynchronize::is_at_safepoint() && \
326 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
327 heap_locking_asserts_params("should be holding the Heap_lock or " \
328 "should be at a safepoint")); \
329 } while (0)
330
331 #define assert_heap_locked_and_not_at_safepoint() \
332 do { \
333 assert(Heap_lock->owned_by_self() && \
334 !SafepointSynchronize::is_at_safepoint(), \
335 heap_locking_asserts_params("should be holding the Heap_lock and " \
336 "should not be at a safepoint")); \
337 } while (0)
338
339 #define assert_heap_not_locked() \
340 do { \
341 assert(!Heap_lock->owned_by_self(), \
342 heap_locking_asserts_params("should not be holding the Heap_lock")); \
343 } while (0)
344
345 #define assert_heap_not_locked_and_not_at_safepoint() \
346 do { \
347 assert(!Heap_lock->owned_by_self() && \
348 !SafepointSynchronize::is_at_safepoint(), \
349 heap_locking_asserts_params("should not be holding the Heap_lock and " \
350 "should not be at a safepoint")); \
351 } while (0)
352
353 #define assert_at_safepoint(_should_be_vm_thread_) \
354 do { \
355 assert(SafepointSynchronize::is_at_safepoint() && \
356 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
357 heap_locking_asserts_params("should be at a safepoint")); \
358 } while (0)
359
360 #define assert_not_at_safepoint() \
361 do { \
362 assert(!SafepointSynchronize::is_at_safepoint(), \
363 heap_locking_asserts_params("should not be at a safepoint")); \
364 } while (0)
365
366 protected:
367
368 // The young region list.
369 G1EdenRegions _eden;
370 G1SurvivorRegions _survivor;
371
372 // The current policy object for the collector.
373 G1Policy* _g1_policy;
374 G1HeapSizingPolicy* _heap_sizing_policy;
375
376 G1CollectionSet _collection_set;
377
378 // This is the second level of trying to allocate a new region. If
379 // new_region() didn't find a region on the free_list, this call will
380 // check whether there's anything available on the
381 // secondary_free_list and/or wait for more regions to appear on
382 // that list, if _free_regions_coming is set.
383 HeapRegion* new_region_try_secondary_free_list(bool is_old);
384
385 // Try to allocate a single non-humongous HeapRegion sufficient for
386 // an allocation of the given word_size. If do_expand is true,
387 // attempt to expand the heap if necessary to satisfy the allocation
388 // request. If the region is to be used as an old region or for a
389 // humongous object, set is_old to true. If not, to false.
390 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand);
391
392 // Initialize a contiguous set of free regions of length num_regions
393 // and starting at index first so that they appear as a single
394 // humongous region.
395 HeapWord* humongous_obj_allocate_initialize_regions(uint first,
396 uint num_regions,
397 size_t word_size,
398 AllocationContext_t context);
399
400 // Attempt to allocate a humongous object of the given size. Return
401 // NULL if unsuccessful.
402 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context);
403
404 // The following two methods, allocate_new_tlab() and
405 // mem_allocate(), are the two main entry points from the runtime
406 // into the G1's allocation routines. They have the following
407 // assumptions:
408 //
409 // * They should both be called outside safepoints.
410 //
411 // * They should both be called without holding the Heap_lock.
412 //
413 // * All allocation requests for new TLABs should go to
414 // allocate_new_tlab().
415 //
416 // * All non-TLAB allocation requests should go to mem_allocate().
417 //
418 // * If either call cannot satisfy the allocation request using the
419 // current allocating region, they will try to get a new one. If
420 // this fails, they will attempt to do an evacuation pause and
421 // retry the allocation.
422 //
423 // * If all allocation attempts fail, even after trying to schedule
424 // an evacuation pause, allocate_new_tlab() will return NULL,
425 // whereas mem_allocate() will attempt a heap expansion and/or
426 // schedule a Full GC.
427 //
428 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
429 // should never be called with word_size being humongous. All
430 // humongous allocation requests should go to mem_allocate() which
431 // will satisfy them with a special path.
432
433 virtual HeapWord* allocate_new_tlab(size_t word_size);
434
435 virtual HeapWord* mem_allocate(size_t word_size,
436 bool* gc_overhead_limit_was_exceeded);
437
438 // The following three methods take a gc_count_before_ret
439 // parameter which is used to return the GC count if the method
440 // returns NULL. Given that we are required to read the GC count
441 // while holding the Heap_lock, and these paths will take the
442 // Heap_lock at some point, it's easier to get them to read the GC
443 // count while holding the Heap_lock before they return NULL instead
444 // of the caller (namely: mem_allocate()) having to also take the
445 // Heap_lock just to read the GC count.
446
447 // First-level mutator allocation attempt: try to allocate out of
448 // the mutator alloc region without taking the Heap_lock. This
449 // should only be used for non-humongous allocations.
450 inline HeapWord* attempt_allocation(size_t word_size,
451 uint* gc_count_before_ret,
452 uint* gclocker_retry_count_ret);
453
454 // Second-level mutator allocation attempt: take the Heap_lock and
455 // retry the allocation attempt, potentially scheduling a GC
456 // pause. This should only be used for non-humongous allocations.
457 HeapWord* attempt_allocation_slow(size_t word_size,
458 AllocationContext_t context,
459 uint* gc_count_before_ret,
460 uint* gclocker_retry_count_ret);
461
462 // Takes the Heap_lock and attempts a humongous allocation. It can
463 // potentially schedule a GC pause.
464 HeapWord* attempt_allocation_humongous(size_t word_size,
465 uint* gc_count_before_ret,
466 uint* gclocker_retry_count_ret);
467
468 // Allocation attempt that should be called during safepoints (e.g.,
469 // at the end of a successful GC). expect_null_mutator_alloc_region
470 // specifies whether the mutator alloc region is expected to be NULL
471 // or not.
472 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
473 AllocationContext_t context,
474 bool expect_null_mutator_alloc_region);
475
476 // These methods are the "callbacks" from the G1AllocRegion class.
477
478 // For mutator alloc regions.
479 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
480 void retire_mutator_alloc_region(HeapRegion* alloc_region,
481 size_t allocated_bytes);
482
483 // For GC alloc regions.
484 bool has_more_regions(InCSetState dest);
485 HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest);
486 void retire_gc_alloc_region(HeapRegion* alloc_region,
487 size_t allocated_bytes, InCSetState dest);
488
489 // - if explicit_gc is true, the GC is for a System.gc() etc,
490 // otherwise it's for a failed allocation.
491 // - if clear_all_soft_refs is true, all soft references should be
492 // cleared during the GC.
493 // - it returns false if it is unable to do the collection due to the
494 // GC locker being active, true otherwise.
495 bool do_full_collection(bool explicit_gc,
496 bool clear_all_soft_refs);
497
498 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread.
499 virtual void do_full_collection(bool clear_all_soft_refs);
500
501 // Resize the heap if necessary after a full collection.
502 void resize_if_necessary_after_full_collection();
503
504 // Callback from VM_G1CollectForAllocation operation.
505 // This function does everything necessary/possible to satisfy a
506 // failed allocation request (including collection, expansion, etc.)
507 HeapWord* satisfy_failed_allocation(size_t word_size,
508 AllocationContext_t context,
509 bool* succeeded);
510 private:
511 // Helper method for satisfy_failed_allocation()
512 HeapWord* satisfy_failed_allocation_helper(size_t word_size,
513 AllocationContext_t context,
514 bool do_gc,
515 bool clear_all_soft_refs,
516 bool expect_null_mutator_alloc_region,
517 bool* gc_succeeded);
518
519 protected:
520 // Attempting to expand the heap sufficiently
521 // to support an allocation of the given "word_size". If
522 // successful, perform the allocation and return the address of the
523 // allocated block, or else "NULL".
524 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context);
525
526 // Preserve any referents discovered by concurrent marking that have not yet been
527 // copied by the STW pause.
528 void preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states);
529 // Process any reference objects discovered during
530 // an incremental evacuation pause.
531 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states);
532
533 // Enqueue any remaining discovered references
534 // after processing.
535 void enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states);
536
537 // Merges the information gathered on a per-thread basis for all worker threads
538 // during GC into global variables.
539 void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states);
540 public:
541 WorkGang* workers() const { return _workers; }
542
543 G1Allocator* allocator() {
544 return _allocator;
545 }
546
547 G1HeapVerifier* verifier() {
548 return _verifier;
549 }
550
551 G1MonitoringSupport* g1mm() {
552 assert(_g1mm != NULL, "should have been initialized");
553 return _g1mm;
554 }
555
556 // Expand the garbage-first heap by at least the given size (in bytes!).
557 // Returns true if the heap was expanded by the requested amount;
558 // false otherwise.
559 // (Rounds up to a HeapRegion boundary.)
560 bool expand(size_t expand_bytes, double* expand_time_ms = NULL);
561
562 // Returns the PLAB statistics for a given destination.
563 inline G1EvacStats* alloc_buffer_stats(InCSetState dest);
564
565 // Determines PLAB size for a given destination.
566 inline size_t desired_plab_sz(InCSetState dest);
567
568 inline AllocationContextStats& allocation_context_stats();
569
570 // Do anything common to GC's.
571 void gc_prologue(bool full);
572 void gc_epilogue(bool full);
573
574 // Modify the reclaim candidate set and test for presence.
575 // These are only valid for starts_humongous regions.
576 inline void set_humongous_reclaim_candidate(uint region, bool value);
577 inline bool is_humongous_reclaim_candidate(uint region);
578
579 // Remove from the reclaim candidate set. Also remove from the
580 // collection set so that later encounters avoid the slow path.
581 inline void set_humongous_is_live(oop obj);
582
583 // Register the given region to be part of the collection set.
584 inline void register_humongous_region_with_cset(uint index);
585 // Register regions with humongous objects (actually on the start region) in
586 // the in_cset_fast_test table.
587 void register_humongous_regions_with_cset();
588 // We register a region with the fast "in collection set" test. We
589 // simply set to true the array slot corresponding to this region.
590 void register_young_region_with_cset(HeapRegion* r) {
591 _in_cset_fast_test.set_in_young(r->hrm_index());
592 }
593 void register_old_region_with_cset(HeapRegion* r) {
594 _in_cset_fast_test.set_in_old(r->hrm_index());
595 }
596 inline void register_ext_region_with_cset(HeapRegion* r) {
597 _in_cset_fast_test.set_ext(r->hrm_index());
598 }
599 void clear_in_cset(const HeapRegion* hr) {
600 _in_cset_fast_test.clear(hr);
601 }
602
603 void clear_cset_fast_test() {
604 _in_cset_fast_test.clear();
605 }
606
607 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause);
608
609 // This is called at the start of either a concurrent cycle or a Full
610 // GC to update the number of old marking cycles started.
611 void increment_old_marking_cycles_started();
612
613 // This is called at the end of either a concurrent cycle or a Full
614 // GC to update the number of old marking cycles completed. Those two
615 // can happen in a nested fashion, i.e., we start a concurrent
616 // cycle, a Full GC happens half-way through it which ends first,
617 // and then the cycle notices that a Full GC happened and ends
618 // too. The concurrent parameter is a boolean to help us do a bit
619 // tighter consistency checking in the method. If concurrent is
620 // false, the caller is the inner caller in the nesting (i.e., the
621 // Full GC). If concurrent is true, the caller is the outer caller
622 // in this nesting (i.e., the concurrent cycle). Further nesting is
623 // not currently supported. The end of this call also notifies
624 // the FullGCCount_lock in case a Java thread is waiting for a full
625 // GC to happen (e.g., it called System.gc() with
626 // +ExplicitGCInvokesConcurrent).
627 void increment_old_marking_cycles_completed(bool concurrent);
628
629 uint old_marking_cycles_completed() {
630 return _old_marking_cycles_completed;
631 }
632
633 G1HRPrinter* hr_printer() { return &_hr_printer; }
634
635 // Allocates a new heap region instance.
636 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr);
637
638 // Allocate the highest free region in the reserved heap. This will commit
639 // regions as necessary.
640 HeapRegion* alloc_highest_free_region();
641
642 // Frees a non-humongous region by initializing its contents and
643 // adding it to the free list that's passed as a parameter (this is
644 // usually a local list which will be appended to the master free
645 // list later). The used bytes of freed regions are accumulated in
646 // pre_used. If skip_remset is true, the region's RSet will not be freed
647 // up. If skip_hot_card_cache is true, the region's hot card cache will not
648 // be freed up. The assumption is that this will be done later.
649 // The locked parameter indicates if the caller has already taken
650 // care of proper synchronization. This may allow some optimizations.
651 void free_region(HeapRegion* hr,
652 FreeRegionList* free_list,
653 bool skip_remset,
654 bool skip_hot_card_cache = false,
655 bool locked = false);
656
657 // It dirties the cards that cover the block so that the post
658 // write barrier never queues anything when updating objects on this
659 // block. It is assumed (and in fact we assert) that the block
660 // belongs to a young region.
661 inline void dirty_young_block(HeapWord* start, size_t word_size);
662
663 // Frees a humongous region by collapsing it into individual regions
664 // and calling free_region() for each of them. The freed regions
665 // will be added to the free list that's passed as a parameter (this
666 // is usually a local list which will be appended to the master free
667 // list later). The used bytes of freed regions are accumulated in
668 // pre_used. If skip_remset is true, the region's RSet will not be freed
669 // up. The assumption is that this will be done later.
670 void free_humongous_region(HeapRegion* hr,
671 FreeRegionList* free_list,
672 bool skip_remset);
673
674 // Facility for allocating in 'archive' regions in high heap memory and
675 // recording the allocated ranges. These should all be called from the
676 // VM thread at safepoints, without the heap lock held. They can be used
677 // to create and archive a set of heap regions which can be mapped at the
678 // same fixed addresses in a subsequent JVM invocation.
679 void begin_archive_alloc_range();
680
681 // Check if the requested size would be too large for an archive allocation.
682 bool is_archive_alloc_too_large(size_t word_size);
683
684 // Allocate memory of the requested size from the archive region. This will
685 // return NULL if the size is too large or if no memory is available. It
686 // does not trigger a garbage collection.
687 HeapWord* archive_mem_allocate(size_t word_size);
688
689 // Optionally aligns the end address and returns the allocated ranges in
690 // an array of MemRegions in order of ascending addresses.
691 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
692 size_t end_alignment_in_bytes = 0);
693
694 // Facility for allocating a fixed range within the heap and marking
695 // the containing regions as 'archive'. For use at JVM init time, when the
696 // caller may mmap archived heap data at the specified range(s).
697 // Verify that the MemRegions specified in the argument array are within the
698 // reserved heap.
699 bool check_archive_addresses(MemRegion* range, size_t count);
700
701 // Commit the appropriate G1 regions containing the specified MemRegions
702 // and mark them as 'archive' regions. The regions in the array must be
703 // non-overlapping and in order of ascending address.
704 bool alloc_archive_regions(MemRegion* range, size_t count);
705
706 // Insert any required filler objects in the G1 regions around the specified
707 // ranges to make the regions parseable. This must be called after
708 // alloc_archive_regions, and after class loading has occurred.
709 void fill_archive_regions(MemRegion* range, size_t count);
710
711 // For each of the specified MemRegions, uncommit the containing G1 regions
712 // which had been allocated by alloc_archive_regions. This should be called
713 // rather than fill_archive_regions at JVM init time if the archive file
714 // mapping failed, with the same non-overlapping and sorted MemRegion array.
715 void dealloc_archive_regions(MemRegion* range, size_t count);
716
717 protected:
718
719 // Shrink the garbage-first heap by at most the given size (in bytes!).
720 // (Rounds down to a HeapRegion boundary.)
721 virtual void shrink(size_t expand_bytes);
722 void shrink_helper(size_t expand_bytes);
723
724 #if TASKQUEUE_STATS
725 static void print_taskqueue_stats_hdr(outputStream* const st);
726 void print_taskqueue_stats() const;
727 void reset_taskqueue_stats();
728 #endif // TASKQUEUE_STATS
729
730 // Schedule the VM operation that will do an evacuation pause to
731 // satisfy an allocation request of word_size. *succeeded will
732 // return whether the VM operation was successful (it did do an
733 // evacuation pause) or not (another thread beat us to it or the GC
734 // locker was active). Given that we should not be holding the
735 // Heap_lock when we enter this method, we will pass the
736 // gc_count_before (i.e., total_collections()) as a parameter since
737 // it has to be read while holding the Heap_lock. Currently, both
738 // methods that call do_collection_pause() release the Heap_lock
739 // before the call, so it's easy to read gc_count_before just before.
740 HeapWord* do_collection_pause(size_t word_size,
741 uint gc_count_before,
742 bool* succeeded,
743 GCCause::Cause gc_cause);
744
745 void wait_for_root_region_scanning();
746
747 // The guts of the incremental collection pause, executed by the vm
748 // thread. It returns false if it is unable to do the collection due
749 // to the GC locker being active, true otherwise
750 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
751
752 // Actually do the work of evacuating the collection set.
753 virtual void evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states);
754
755 void pre_evacuate_collection_set();
756 void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss);
757
758 // Print the header for the per-thread termination statistics.
759 static void print_termination_stats_hdr();
760 // Print actual per-thread termination statistics.
761 void print_termination_stats(uint worker_id,
762 double elapsed_ms,
763 double strong_roots_ms,
764 double term_ms,
765 size_t term_attempts,
766 size_t alloc_buffer_waste,
767 size_t undo_waste) const;
768 // Update object copying statistics.
769 void record_obj_copy_mem_stats();
770
771 // The hot card cache for remembered set insertion optimization.
772 G1HotCardCache* _hot_card_cache;
773
774 // The g1 remembered set of the heap.
775 G1RemSet* _g1_rem_set;
776
777 // A set of cards that cover the objects for which the Rsets should be updated
778 // concurrently after the collection.
779 DirtyCardQueueSet _dirty_card_queue_set;
780
781 // The closure used to refine a single card.
782 RefineCardTableEntryClosure* _refine_cte_cl;
783
784 // After a collection pause, convert the regions in the collection set into free
785 // regions.
786 void free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words);
787
788 // Abandon the current collection set without recording policy
789 // statistics or updating free lists.
790 void abandon_collection_set(G1CollectionSet* collection_set);
791
792 // The concurrent marker (and the thread it runs in.)
793 G1ConcurrentMark* _cm;
794 ConcurrentMarkThread* _cmThread;
795
796 // The concurrent refiner.
797 ConcurrentG1Refine* _cg1r;
798
799 // The parallel task queues
800 RefToScanQueueSet *_task_queues;
801
802 // True iff a evacuation has failed in the current collection.
803 bool _evacuation_failed;
804
805 EvacuationFailedInfo* _evacuation_failed_info_array;
806
807 // Failed evacuations cause some logical from-space objects to have
808 // forwarding pointers to themselves. Reset them.
809 void remove_self_forwarding_pointers();
810
811 // Restore the objects in the regions in the collection set after an
812 // evacuation failure.
813 void restore_after_evac_failure();
814
815 PreservedMarksSet _preserved_marks_set;
816
817 // Preserve the mark of "obj", if necessary, in preparation for its mark
818 // word being overwritten with a self-forwarding-pointer.
819 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m);
820
821 #ifndef PRODUCT
822 // Support for forcing evacuation failures. Analogous to
823 // PromotionFailureALot for the other collectors.
824
825 // Records whether G1EvacuationFailureALot should be in effect
826 // for the current GC
827 bool _evacuation_failure_alot_for_current_gc;
828
829 // Used to record the GC number for interval checking when
830 // determining whether G1EvaucationFailureALot is in effect
831 // for the current GC.
832 size_t _evacuation_failure_alot_gc_number;
833
834 // Count of the number of evacuations between failures.
835 volatile size_t _evacuation_failure_alot_count;
836
837 // Set whether G1EvacuationFailureALot should be in effect
838 // for the current GC (based upon the type of GC and which
839 // command line flags are set);
840 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young,
841 bool during_initial_mark,
842 bool during_marking);
843
844 inline void set_evacuation_failure_alot_for_current_gc();
845
846 // Return true if it's time to cause an evacuation failure.
847 inline bool evacuation_should_fail();
848
849 // Reset the G1EvacuationFailureALot counters. Should be called at
850 // the end of an evacuation pause in which an evacuation failure occurred.
851 inline void reset_evacuation_should_fail();
852 #endif // !PRODUCT
853
854 // ("Weak") Reference processing support.
855 //
856 // G1 has 2 instances of the reference processor class. One
857 // (_ref_processor_cm) handles reference object discovery
858 // and subsequent processing during concurrent marking cycles.
859 //
860 // The other (_ref_processor_stw) handles reference object
861 // discovery and processing during full GCs and incremental
862 // evacuation pauses.
863 //
864 // During an incremental pause, reference discovery will be
865 // temporarily disabled for _ref_processor_cm and will be
866 // enabled for _ref_processor_stw. At the end of the evacuation
867 // pause references discovered by _ref_processor_stw will be
868 // processed and discovery will be disabled. The previous
869 // setting for reference object discovery for _ref_processor_cm
870 // will be re-instated.
871 //
872 // At the start of marking:
873 // * Discovery by the CM ref processor is verified to be inactive
874 // and it's discovered lists are empty.
875 // * Discovery by the CM ref processor is then enabled.
876 //
877 // At the end of marking:
878 // * Any references on the CM ref processor's discovered
879 // lists are processed (possibly MT).
880 //
881 // At the start of full GC we:
882 // * Disable discovery by the CM ref processor and
883 // empty CM ref processor's discovered lists
884 // (without processing any entries).
885 // * Verify that the STW ref processor is inactive and it's
886 // discovered lists are empty.
887 // * Temporarily set STW ref processor discovery as single threaded.
888 // * Temporarily clear the STW ref processor's _is_alive_non_header
889 // field.
890 // * Finally enable discovery by the STW ref processor.
891 //
892 // The STW ref processor is used to record any discovered
893 // references during the full GC.
894 //
895 // At the end of a full GC we:
896 // * Enqueue any reference objects discovered by the STW ref processor
897 // that have non-live referents. This has the side-effect of
898 // making the STW ref processor inactive by disabling discovery.
899 // * Verify that the CM ref processor is still inactive
900 // and no references have been placed on it's discovered
901 // lists (also checked as a precondition during initial marking).
902
903 // The (stw) reference processor...
904 ReferenceProcessor* _ref_processor_stw;
905
906 STWGCTimer* _gc_timer_stw;
907
908 G1NewTracer* _gc_tracer_stw;
909
910 // During reference object discovery, the _is_alive_non_header
911 // closure (if non-null) is applied to the referent object to
912 // determine whether the referent is live. If so then the
913 // reference object does not need to be 'discovered' and can
914 // be treated as a regular oop. This has the benefit of reducing
915 // the number of 'discovered' reference objects that need to
916 // be processed.
917 //
918 // Instance of the is_alive closure for embedding into the
919 // STW reference processor as the _is_alive_non_header field.
920 // Supplying a value for the _is_alive_non_header field is
921 // optional but doing so prevents unnecessary additions to
922 // the discovered lists during reference discovery.
923 G1STWIsAliveClosure _is_alive_closure_stw;
924
925 // The (concurrent marking) reference processor...
926 ReferenceProcessor* _ref_processor_cm;
927
928 // Instance of the concurrent mark is_alive closure for embedding
929 // into the Concurrent Marking reference processor as the
930 // _is_alive_non_header field. Supplying a value for the
931 // _is_alive_non_header field is optional but doing so prevents
932 // unnecessary additions to the discovered lists during reference
933 // discovery.
934 G1CMIsAliveClosure _is_alive_closure_cm;
935
936 volatile bool _free_regions_coming;
937
938 public:
939
940 void set_refine_cte_cl_concurrency(bool concurrent);
941
942 RefToScanQueue *task_queue(uint i) const;
943
944 uint num_task_queues() const;
945
946 // A set of cards where updates happened during the GC
947 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
948
949 // Create a G1CollectedHeap with the specified policy.
950 // Must call the initialize method afterwards.
951 // May not return if something goes wrong.
952 G1CollectedHeap(G1CollectorPolicy* policy);
953
954 // Initialize the G1CollectedHeap to have the initial and
955 // maximum sizes and remembered and barrier sets
956 // specified by the policy object.
957 jint initialize();
958
959 virtual void stop();
960
961 // Return the (conservative) maximum heap alignment for any G1 heap
962 static size_t conservative_max_heap_alignment();
963
964 // Does operations required after initialization has been done.
965 void post_initialize();
966
967 // Initialize weak reference processing.
968 void ref_processing_init();
969
970 virtual Name kind() const {
971 return CollectedHeap::G1CollectedHeap;
972 }
973
974 virtual const char* name() const {
975 return "G1";
976 }
977
978 const G1CollectorState* collector_state() const { return &_collector_state; }
979 G1CollectorState* collector_state() { return &_collector_state; }
980
981 // The current policy object for the collector.
982 G1Policy* g1_policy() const { return _g1_policy; }
983
984 const G1CollectionSet* collection_set() const { return &_collection_set; }
985 G1CollectionSet* collection_set() { return &_collection_set; }
986
987 virtual CollectorPolicy* collector_policy() const;
988
989 // Adaptive size policy. No such thing for g1.
990 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
991
992 // The rem set and barrier set.
993 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
994
995 // Try to minimize the remembered set.
996 void scrub_rem_set();
997
998 uint get_gc_time_stamp() {
999 return _gc_time_stamp;
1000 }
1001
1002 inline void reset_gc_time_stamp();
1003
1004 void check_gc_time_stamps() PRODUCT_RETURN;
1005
1006 inline void increment_gc_time_stamp();
1007
1008 // Reset the given region's GC timestamp. If it's starts humongous,
1009 // also reset the GC timestamp of its corresponding
1010 // continues humongous regions too.
1011 void reset_gc_time_stamps(HeapRegion* hr);
1012
1013 // Apply the given closure on all cards in the Hot Card Cache, emptying it.
1014 void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i);
1015
1016 // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it.
1017 void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i);
1018
1019 // The shared block offset table array.
1020 G1BlockOffsetTable* bot() const { return _bot; }
1021
1022 // Reference Processing accessors
1023
1024 // The STW reference processor....
1025 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1026
1027 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; }
1028
1029 // The Concurrent Marking reference processor...
1030 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1031
1032 virtual size_t capacity() const;
1033 virtual size_t used() const;
1034 // This should be called when we're not holding the heap lock. The
1035 // result might be a bit inaccurate.
1036 size_t used_unlocked() const;
1037 size_t recalculate_used() const;
1038
1039 // These virtual functions do the actual allocation.
1040 // Some heaps may offer a contiguous region for shared non-blocking
1041 // allocation, via inlined code (by exporting the address of the top and
1042 // end fields defining the extent of the contiguous allocation region.)
1043 // But G1CollectedHeap doesn't yet support this.
1044
1045 virtual bool is_maximal_no_gc() const {
1046 return _hrm.available() == 0;
1047 }
1048
1049 // The current number of regions in the heap.
1050 uint num_regions() const { return _hrm.length(); }
1051
1052 // The max number of regions in the heap.
1053 uint max_regions() const { return _hrm.max_length(); }
1054
1055 // The number of regions that are completely free.
1056 uint num_free_regions() const { return _hrm.num_free_regions(); }
1057
1058 MemoryUsage get_auxiliary_data_memory_usage() const {
1059 return _hrm.get_auxiliary_data_memory_usage();
1060 }
1061
1062 // The number of regions that are not completely free.
1063 uint num_used_regions() const { return num_regions() - num_free_regions(); }
1064
1065 #ifdef ASSERT
1066 bool is_on_master_free_list(HeapRegion* hr) {
1067 return _hrm.is_free(hr);
1068 }
1069 #endif // ASSERT
1070
1071 // Wrapper for the region list operations that can be called from
1072 // methods outside this class.
1073
1074 void secondary_free_list_add(FreeRegionList* list) {
1075 _secondary_free_list.add_ordered(list);
1076 }
1077
1078 void append_secondary_free_list() {
1079 _hrm.insert_list_into_free_list(&_secondary_free_list);
1080 }
1081
1082 void append_secondary_free_list_if_not_empty_with_lock() {
1083 // If the secondary free list looks empty there's no reason to
1084 // take the lock and then try to append it.
1085 if (!_secondary_free_list.is_empty()) {
1086 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1087 append_secondary_free_list();
1088 }
1089 }
1090
1091 inline void old_set_add(HeapRegion* hr);
1092 inline void old_set_remove(HeapRegion* hr);
1093
1094 size_t non_young_capacity_bytes() {
1095 return (_old_set.length() + _humongous_set.length()) * HeapRegion::GrainBytes;
1096 }
1097
1098 void set_free_regions_coming();
1099 void reset_free_regions_coming();
1100 bool free_regions_coming() { return _free_regions_coming; }
1101 void wait_while_free_regions_coming();
1102
1103 // Determine whether the given region is one that we are using as an
1104 // old GC alloc region.
1105 bool is_old_gc_alloc_region(HeapRegion* hr);
1106
1107 // Perform a collection of the heap; intended for use in implementing
1108 // "System.gc". This probably implies as full a collection as the
1109 // "CollectedHeap" supports.
1110 virtual void collect(GCCause::Cause cause);
1111
1112 virtual bool copy_allocation_context_stats(const jint* contexts,
1113 jlong* totals,
1114 jbyte* accuracy,
1115 jint len);
1116
1117 // True iff an evacuation has failed in the most-recent collection.
1118 bool evacuation_failed() { return _evacuation_failed; }
1119
1120 void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed);
1121 void prepend_to_freelist(FreeRegionList* list);
1122 void decrement_summary_bytes(size_t bytes);
1123
1124 virtual bool is_in(const void* p) const;
1125 #ifdef ASSERT
1126 // Returns whether p is in one of the available areas of the heap. Slow but
1127 // extensive version.
1128 bool is_in_exact(const void* p) const;
1129 #endif
1130
1131 // Return "TRUE" iff the given object address is within the collection
1132 // set. Slow implementation.
1133 bool obj_in_cs(oop obj);
1134
1135 inline bool is_in_cset(const HeapRegion *hr);
1136 inline bool is_in_cset(oop obj);
1137
1138 inline bool is_in_cset_or_humongous(const oop obj);
1139
1140 private:
1141 // This array is used for a quick test on whether a reference points into
1142 // the collection set or not. Each of the array's elements denotes whether the
1143 // corresponding region is in the collection set or not.
1144 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test;
1145
1146 public:
1147
1148 inline InCSetState in_cset_state(const oop obj);
1149
1150 // Return "TRUE" iff the given object address is in the reserved
1151 // region of g1.
1152 bool is_in_g1_reserved(const void* p) const {
1153 return _hrm.reserved().contains(p);
1154 }
1155
1156 // Returns a MemRegion that corresponds to the space that has been
1157 // reserved for the heap
1158 MemRegion g1_reserved() const {
1159 return _hrm.reserved();
1160 }
1161
1162 virtual bool is_in_closed_subset(const void* p) const;
1163
1164 G1SATBCardTableLoggingModRefBS* g1_barrier_set() {
1165 return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set());
1166 }
1167
1168 // Iteration functions.
1169
1170 // Iterate over all objects, calling "cl.do_object" on each.
1171 virtual void object_iterate(ObjectClosure* cl);
1172
1173 virtual void safe_object_iterate(ObjectClosure* cl) {
1174 object_iterate(cl);
1175 }
1176
1177 // Iterate over heap regions, in address order, terminating the
1178 // iteration early if the "doHeapRegion" method returns "true".
1179 void heap_region_iterate(HeapRegionClosure* blk) const;
1180
1181 // Return the region with the given index. It assumes the index is valid.
1182 inline HeapRegion* region_at(uint index) const;
1183
1184 // Return the next region (by index) that is part of the same
1185 // humongous object that hr is part of.
1186 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const;
1187
1188 // Calculate the region index of the given address. Given address must be
1189 // within the heap.
1190 inline uint addr_to_region(HeapWord* addr) const;
1191
1192 inline HeapWord* bottom_addr_for_region(uint index) const;
1193
1194 // Iterate over the heap regions in parallel. Assumes that this will be called
1195 // in parallel by ParallelGCThreads worker threads with distinct worker ids
1196 // in the range [0..max(ParallelGCThreads-1, 1)]. Applies "blk->doHeapRegion"
1197 // to each of the regions, by attempting to claim the region using the
1198 // HeapRegionClaimer and, if successful, applying the closure to the claimed
1199 // region. The concurrent argument should be set to true if iteration is
1200 // performed concurrently, during which no assumptions are made for consistent
1201 // attributes of the heap regions (as they might be modified while iterating).
1202 void heap_region_par_iterate(HeapRegionClosure* cl,
1203 uint worker_id,
1204 HeapRegionClaimer* hrclaimer,
1205 bool concurrent = false) const;
1206
1207 // Iterate over the regions (if any) in the current collection set.
1208 void collection_set_iterate(HeapRegionClosure* blk);
1209
1210 // Iterate over the regions (if any) in the current collection set. Starts the
1211 // iteration over the entire collection set so that the start regions of a given
1212 // worker id over the set active_workers are evenly spread across the set of
1213 // collection set regions.
1214 void collection_set_iterate_from(HeapRegionClosure *blk, uint worker_id);
1215
1216 HeapRegion* next_compaction_region(const HeapRegion* from) const;
1217
1218 // Returns the HeapRegion that contains addr. addr must not be NULL.
1219 template <class T>
1220 inline HeapRegion* heap_region_containing(const T addr) const;
1221
1222 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1223 // each address in the (reserved) heap is a member of exactly
1224 // one block. The defining characteristic of a block is that it is
1225 // possible to find its size, and thus to progress forward to the next
1226 // block. (Blocks may be of different sizes.) Thus, blocks may
1227 // represent Java objects, or they might be free blocks in a
1228 // free-list-based heap (or subheap), as long as the two kinds are
1229 // distinguishable and the size of each is determinable.
1230
1231 // Returns the address of the start of the "block" that contains the
1232 // address "addr". We say "blocks" instead of "object" since some heaps
1233 // may not pack objects densely; a chunk may either be an object or a
1234 // non-object.
1235 virtual HeapWord* block_start(const void* addr) const;
1236
1237 // Requires "addr" to be the start of a chunk, and returns its size.
1238 // "addr + size" is required to be the start of a new chunk, or the end
1239 // of the active area of the heap.
1240 virtual size_t block_size(const HeapWord* addr) const;
1241
1242 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1243 // the block is an object.
1244 virtual bool block_is_obj(const HeapWord* addr) const;
1245
1246 // Section on thread-local allocation buffers (TLABs)
1247 // See CollectedHeap for semantics.
1248
1249 bool supports_tlab_allocation() const;
1250 size_t tlab_capacity(Thread* ignored) const;
1251 size_t tlab_used(Thread* ignored) const;
1252 size_t max_tlab_size() const;
1253 size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1254
1255 // Can a compiler initialize a new object without store barriers?
1256 // This permission only extends from the creation of a new object
1257 // via a TLAB up to the first subsequent safepoint. If such permission
1258 // is granted for this heap type, the compiler promises to call
1259 // defer_store_barrier() below on any slow path allocation of
1260 // a new object for which such initializing store barriers will
1261 // have been elided. G1, like CMS, allows this, but should be
1262 // ready to provide a compensating write barrier as necessary
1263 // if that storage came out of a non-young region. The efficiency
1264 // of this implementation depends crucially on being able to
1265 // answer very efficiently in constant time whether a piece of
1266 // storage in the heap comes from a young region or not.
1267 // See ReduceInitialCardMarks.
1268 virtual bool can_elide_tlab_store_barriers() const {
1269 return true;
1270 }
1271
1272 virtual bool card_mark_must_follow_store() const {
1273 return true;
1274 }
1275
1276 inline bool is_in_young(const oop obj);
1277
1278 virtual bool is_scavengable(const void* addr);
1279
1280 // We don't need barriers for initializing stores to objects
1281 // in the young gen: for the SATB pre-barrier, there is no
1282 // pre-value that needs to be remembered; for the remembered-set
1283 // update logging post-barrier, we don't maintain remembered set
1284 // information for young gen objects.
1285 virtual inline bool can_elide_initializing_store_barrier(oop new_obj);
1286
1287 // Returns "true" iff the given word_size is "very large".
1288 static bool is_humongous(size_t word_size) {
1289 // Note this has to be strictly greater-than as the TLABs
1290 // are capped at the humongous threshold and we want to
1291 // ensure that we don't try to allocate a TLAB as
1292 // humongous and that we don't allocate a humongous
1293 // object in a TLAB.
1294 return word_size > _humongous_object_threshold_in_words;
1295 }
1296
1297 // Returns the humongous threshold for a specific region size
1298 static size_t humongous_threshold_for(size_t region_size) {
1299 return (region_size / 2);
1300 }
1301
1302 // Returns the number of regions the humongous object of the given word size
1303 // requires.
1304 static size_t humongous_obj_size_in_regions(size_t word_size);
1305
1306 // Print the maximum heap capacity.
1307 virtual size_t max_capacity() const;
1308
1309 virtual jlong millis_since_last_gc();
1310
1311
1312 // Convenience function to be used in situations where the heap type can be
1313 // asserted to be this type.
1314 static G1CollectedHeap* heap();
1315
1316 void set_region_short_lived_locked(HeapRegion* hr);
1317 // add appropriate methods for any other surv rate groups
1318
1319 const G1SurvivorRegions* survivor() const { return &_survivor; }
1320
1321 uint survivor_regions_count() const {
1322 return _survivor.length();
1323 }
1324
1325 uint eden_regions_count() const {
1326 return _eden.length();
1327 }
1328
1329 uint young_regions_count() const {
1330 return _eden.length() + _survivor.length();
1331 }
1332
1333 uint old_regions_count() const { return _old_set.length(); }
1334
1335 uint humongous_regions_count() const { return _humongous_set.length(); }
1336
1337 #ifdef ASSERT
1338 bool check_young_list_empty();
1339 #endif
1340
1341 // *** Stuff related to concurrent marking. It's not clear to me that so
1342 // many of these need to be public.
1343
1344 // The functions below are helper functions that a subclass of
1345 // "CollectedHeap" can use in the implementation of its virtual
1346 // functions.
1347 // This performs a concurrent marking of the live objects in a
1348 // bitmap off to the side.
1349 void doConcurrentMark();
1350
1351 bool isMarkedPrev(oop obj) const;
1352 bool isMarkedNext(oop obj) const;
1353
1354 // Determine if an object is dead, given the object and also
1355 // the region to which the object belongs. An object is dead
1356 // iff a) it was not allocated since the last mark, b) it
1357 // is not marked, and c) it is not in an archive region.
1358 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1359 return
1360 !hr->obj_allocated_since_prev_marking(obj) &&
1361 !isMarkedPrev(obj) &&
1362 !hr->is_archive();
1363 }
1364
1365 // This function returns true when an object has been
1366 // around since the previous marking and hasn't yet
1367 // been marked during this marking, and is not in an archive region.
1368 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1369 return
1370 !hr->obj_allocated_since_next_marking(obj) &&
1371 !isMarkedNext(obj) &&
1372 !hr->is_archive();
1373 }
1374
1375 // Determine if an object is dead, given only the object itself.
1376 // This will find the region to which the object belongs and
1377 // then call the region version of the same function.
1378
1379 // Added if it is NULL it isn't dead.
1380
1381 inline bool is_obj_dead(const oop obj) const;
1382
1383 inline bool is_obj_ill(const oop obj) const;
1384
1385 G1ConcurrentMark* concurrent_mark() const { return _cm; }
1386
1387 // Refinement
1388
1389 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1390
1391 // Optimized nmethod scanning support routines
1392
1393 // Register the given nmethod with the G1 heap.
1394 virtual void register_nmethod(nmethod* nm);
1395
1396 // Unregister the given nmethod from the G1 heap.
1397 virtual void unregister_nmethod(nmethod* nm);
1398
1399 // Free up superfluous code root memory.
1400 void purge_code_root_memory();
1401
1402 // Rebuild the strong code root lists for each region
1403 // after a full GC.
1404 void rebuild_strong_code_roots();
1405
1406 // Delete entries for dead interned string and clean up unreferenced symbols
1407 // in symbol table, possibly in parallel.
1408 void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true);
1409
1410 // Parallel phase of unloading/cleaning after G1 concurrent mark.
1411 void parallel_cleaning(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool class_unloading_occurred);
1412
1413 // Redirty logged cards in the refinement queue.
1414 void redirty_logged_cards();
1415 // Verification
1416
1417 // Perform any cleanup actions necessary before allowing a verification.
1418 virtual void prepare_for_verify();
1419
1420 // Perform verification.
1421
1422 // vo == UsePrevMarking -> use "prev" marking information,
1423 // vo == UseNextMarking -> use "next" marking information
1424 // vo == UseMarkWord -> use the mark word in the object header
1425 //
1426 // NOTE: Only the "prev" marking information is guaranteed to be
1427 // consistent most of the time, so most calls to this should use
1428 // vo == UsePrevMarking.
1429 // Currently, there is only one case where this is called with
1430 // vo == UseNextMarking, which is to verify the "next" marking
1431 // information at the end of remark.
1432 // Currently there is only one place where this is called with
1433 // vo == UseMarkWord, which is to verify the marking during a
1434 // full GC.
1435 void verify(VerifyOption vo);
1436
1437 // The methods below are here for convenience and dispatch the
1438 // appropriate method depending on value of the given VerifyOption
1439 // parameter. The values for that parameter, and their meanings,
1440 // are the same as those above.
1441
1442 bool is_obj_dead_cond(const oop obj,
1443 const HeapRegion* hr,
1444 const VerifyOption vo) const;
1445
1446 bool is_obj_dead_cond(const oop obj,
1447 const VerifyOption vo) const;
1448
1449 G1HeapSummary create_g1_heap_summary();
1450 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats);
1451
1452 // Printing
1453 private:
1454 void print_heap_regions() const;
1455 void print_regions_on(outputStream* st) const;
1456
1457 public:
1458 virtual void print_on(outputStream* st) const;
1459 virtual void print_extended_on(outputStream* st) const;
1460 virtual void print_on_error(outputStream* st) const;
1461
1462 virtual void print_gc_threads_on(outputStream* st) const;
1463 virtual void gc_threads_do(ThreadClosure* tc) const;
1464
1465 // Override
1466 void print_tracing_info() const;
1467
1468 // The following two methods are helpful for debugging RSet issues.
1469 void print_cset_rsets() PRODUCT_RETURN;
1470 void print_all_rsets() PRODUCT_RETURN;
1471
1472 public:
1473 size_t pending_card_num();
1474
1475 protected:
1476 size_t _max_heap_capacity;
1477 };
1478
1479 class G1ParEvacuateFollowersClosure : public VoidClosure {
1480 private:
1481 double _start_term;
1482 double _term_time;
1483 size_t _term_attempts;
1484
1485 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
1486 void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
1487 protected:
1488 G1CollectedHeap* _g1h;
1489 G1ParScanThreadState* _par_scan_state;
1490 RefToScanQueueSet* _queues;
1491 ParallelTaskTerminator* _terminator;
1492
1493 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
1494 RefToScanQueueSet* queues() { return _queues; }
1495 ParallelTaskTerminator* terminator() { return _terminator; }
1496
1497 public:
1498 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
1499 G1ParScanThreadState* par_scan_state,
1500 RefToScanQueueSet* queues,
1501 ParallelTaskTerminator* terminator)
1502 : _g1h(g1h), _par_scan_state(par_scan_state),
1503 _queues(queues), _terminator(terminator),
1504 _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
1505
1506 void do_void();
1507
1508 double term_time() const { return _term_time; }
1509 size_t term_attempts() const { return _term_attempts; }
1510
1511 private:
1512 inline bool offer_termination();
1513 };
1514
1515 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP
--- EOF ---