1 /*
2 * Copyright (c) 2001, 2015, 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
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
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20 * or visit www.oracle.com if you need additional information or have any
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23 */
24
25 #ifndef SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP
26 #define SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP
27
28 #include "gc/g1/concurrentMark.hpp"
29 #include "gc/g1/evacuationInfo.hpp"
30 #include "gc/g1/g1AllocRegion.hpp"
31 #include "gc/g1/g1AllocationContext.hpp"
32 #include "gc/g1/g1Allocator.hpp"
33 #include "gc/g1/g1BiasedArray.hpp"
34 #include "gc/g1/g1CollectorState.hpp"
35 #include "gc/g1/g1HRPrinter.hpp"
36 #include "gc/g1/g1InCSetState.hpp"
37 #include "gc/g1/g1MonitoringSupport.hpp"
38 #include "gc/g1/g1SATBCardTableModRefBS.hpp"
39 #include "gc/g1/g1YCTypes.hpp"
40 #include "gc/g1/hSpaceCounters.hpp"
41 #include "gc/g1/heapRegionManager.hpp"
42 #include "gc/g1/heapRegionSet.hpp"
43 #include "gc/shared/barrierSet.hpp"
44 #include "gc/shared/collectedHeap.hpp"
45 #include "memory/memRegion.hpp"
46 #include "utilities/stack.hpp"
47
48 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
49 // It uses the "Garbage First" heap organization and algorithm, which
50 // may combine concurrent marking with parallel, incremental compaction of
51 // heap subsets that will yield large amounts of garbage.
52
53 // Forward declarations
54 class HeapRegion;
55 class HRRSCleanupTask;
56 class GenerationSpec;
57 class OopsInHeapRegionClosure;
58 class G1KlassScanClosure;
59 class G1ParScanThreadState;
60 class ObjectClosure;
61 class SpaceClosure;
62 class CompactibleSpaceClosure;
63 class Space;
64 class G1CollectorPolicy;
65 class GenRemSet;
66 class G1RemSet;
67 class HeapRegionRemSetIterator;
68 class ConcurrentMark;
69 class ConcurrentMarkThread;
70 class ConcurrentG1Refine;
71 class ConcurrentGCTimer;
72 class GenerationCounters;
73 class STWGCTimer;
74 class G1NewTracer;
75 class G1OldTracer;
76 class EvacuationFailedInfo;
77 class nmethod;
78 class Ticks;
79 class FlexibleWorkGang;
80
81 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue;
82 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
83
84 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
85 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
86
87 class YoungList : public CHeapObj<mtGC> {
88 private:
89 G1CollectedHeap* _g1h;
90
91 HeapRegion* _head;
92
93 HeapRegion* _survivor_head;
94 HeapRegion* _survivor_tail;
95
96 HeapRegion* _curr;
97
98 uint _length;
99 uint _survivor_length;
100
101 size_t _last_sampled_rs_lengths;
102 size_t _sampled_rs_lengths;
103
104 void empty_list(HeapRegion* list);
105
106 public:
107 YoungList(G1CollectedHeap* g1h);
108
109 void push_region(HeapRegion* hr);
110 void add_survivor_region(HeapRegion* hr);
111
112 void empty_list();
113 bool is_empty() { return _length == 0; }
114 uint length() { return _length; }
115 uint eden_length() { return length() - survivor_length(); }
116 uint survivor_length() { return _survivor_length; }
117
118 // Currently we do not keep track of the used byte sum for the
119 // young list and the survivors and it'd be quite a lot of work to
120 // do so. When we'll eventually replace the young list with
121 // instances of HeapRegionLinkedList we'll get that for free. So,
122 // we'll report the more accurate information then.
123 size_t eden_used_bytes() {
124 assert(length() >= survivor_length(), "invariant");
125 return (size_t) eden_length() * HeapRegion::GrainBytes;
126 }
127 size_t survivor_used_bytes() {
128 return (size_t) survivor_length() * HeapRegion::GrainBytes;
129 }
130
131 void rs_length_sampling_init();
132 bool rs_length_sampling_more();
133 void rs_length_sampling_next();
134
135 void reset_sampled_info() {
136 _last_sampled_rs_lengths = 0;
137 }
138 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }
139
140 // for development purposes
141 void reset_auxilary_lists();
142 void clear() { _head = NULL; _length = 0; }
143
144 void clear_survivors() {
145 _survivor_head = NULL;
146 _survivor_tail = NULL;
147 _survivor_length = 0;
148 }
149
150 HeapRegion* first_region() { return _head; }
151 HeapRegion* first_survivor_region() { return _survivor_head; }
152 HeapRegion* last_survivor_region() { return _survivor_tail; }
153
154 // debugging
155 bool check_list_well_formed();
156 bool check_list_empty(bool check_sample = true);
157 void print();
158 };
159
160 // The G1 STW is alive closure.
161 // An instance is embedded into the G1CH and used as the
162 // (optional) _is_alive_non_header closure in the STW
163 // reference processor. It is also extensively used during
164 // reference processing during STW evacuation pauses.
165 class G1STWIsAliveClosure: public BoolObjectClosure {
166 G1CollectedHeap* _g1;
167 public:
168 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
169 bool do_object_b(oop p);
170 };
171
172 class RefineCardTableEntryClosure;
173
174 class G1RegionMappingChangedListener : public G1MappingChangedListener {
175 private:
176 void reset_from_card_cache(uint start_idx, size_t num_regions);
177 public:
178 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
179 };
180
181 class G1CollectedHeap : public CollectedHeap {
182 friend class VM_CollectForMetadataAllocation;
183 friend class VM_G1CollectForAllocation;
184 friend class VM_G1CollectFull;
185 friend class VM_G1IncCollectionPause;
186 friend class VMStructs;
187 friend class MutatorAllocRegion;
188 friend class SurvivorGCAllocRegion;
189 friend class OldGCAllocRegion;
190 friend class G1Allocator;
191 friend class G1ArchiveAllocator;
192
193 // Closures used in implementation.
194 friend class G1ParScanThreadState;
195 friend class G1ParTask;
196 friend class G1ParGCAllocator;
197 friend class G1PrepareCompactClosure;
198
199 // Other related classes.
200 friend class HeapRegionClaimer;
201
202 // Testing classes.
203 friend class G1CheckCSetFastTableClosure;
204
205 private:
206 FlexibleWorkGang* _workers;
207
208 static size_t _humongous_object_threshold_in_words;
209
210 // The secondary free list which contains regions that have been
211 // freed up during the cleanup process. This will be appended to
212 // the master free list when appropriate.
213 FreeRegionList _secondary_free_list;
214
215 // It keeps track of the old regions.
216 HeapRegionSet _old_set;
217
218 // It keeps track of the humongous regions.
219 HeapRegionSet _humongous_set;
220
221 void eagerly_reclaim_humongous_regions();
222
223 // The number of regions we could create by expansion.
224 uint _expansion_regions;
225
226 // The block offset table for the G1 heap.
227 G1BlockOffsetSharedArray* _bot_shared;
228
229 // Tears down the region sets / lists so that they are empty and the
230 // regions on the heap do not belong to a region set / list. The
231 // only exception is the humongous set which we leave unaltered. If
232 // free_list_only is true, it will only tear down the master free
233 // list. It is called before a Full GC (free_list_only == false) or
234 // before heap shrinking (free_list_only == true).
235 void tear_down_region_sets(bool free_list_only);
236
237 // Rebuilds the region sets / lists so that they are repopulated to
238 // reflect the contents of the heap. The only exception is the
239 // humongous set which was not torn down in the first place. If
240 // free_list_only is true, it will only rebuild the master free
241 // list. It is called after a Full GC (free_list_only == false) or
242 // after heap shrinking (free_list_only == true).
243 void rebuild_region_sets(bool free_list_only);
244
245 // Callback for region mapping changed events.
246 G1RegionMappingChangedListener _listener;
247
248 // The sequence of all heap regions in the heap.
249 HeapRegionManager _hrm;
250
251 // Class that handles the different kinds of allocations.
252 G1Allocator* _allocator;
253
254 // Outside of GC pauses, the number of bytes used in all regions other
255 // than the current allocation region(s).
256 size_t _summary_bytes_used;
257
258 void increase_used(size_t bytes);
259 void decrease_used(size_t bytes);
260
261 void set_used(size_t bytes);
262
263 // Class that handles archive allocation ranges.
264 G1ArchiveAllocator* _archive_allocator;
265
266 // Statistics for each allocation context
267 AllocationContextStats _allocation_context_stats;
268
269 // PLAB sizing policy for survivors.
270 PLABStats _survivor_plab_stats;
271
272 // PLAB sizing policy for tenured objects.
273 PLABStats _old_plab_stats;
274
275 // It specifies whether we should attempt to expand the heap after a
276 // region allocation failure. If heap expansion fails we set this to
277 // false so that we don't re-attempt the heap expansion (it's likely
278 // that subsequent expansion attempts will also fail if one fails).
279 // Currently, it is only consulted during GC and it's reset at the
280 // start of each GC.
281 bool _expand_heap_after_alloc_failure;
282
283 // It resets the mutator alloc region before new allocations can take place.
284 void init_mutator_alloc_region();
285
286 // It releases the mutator alloc region.
287 void release_mutator_alloc_region();
288
289 // It initializes the GC alloc regions at the start of a GC.
290 void init_gc_alloc_regions(EvacuationInfo& evacuation_info);
291
292 // It releases the GC alloc regions at the end of a GC.
293 void release_gc_alloc_regions(EvacuationInfo& evacuation_info);
294
295 // It does any cleanup that needs to be done on the GC alloc regions
296 // before a Full GC.
297 void abandon_gc_alloc_regions();
298
299 // Helper for monitoring and management support.
300 G1MonitoringSupport* _g1mm;
301
302 // Records whether the region at the given index is (still) a
303 // candidate for eager reclaim. Only valid for humongous start
304 // regions; other regions have unspecified values. Humongous start
305 // regions are initialized at start of collection pause, with
306 // candidates removed from the set as they are found reachable from
307 // roots or the young generation.
308 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> {
309 protected:
310 bool default_value() const { return false; }
311 public:
312 void clear() { G1BiasedMappedArray<bool>::clear(); }
313 void set_candidate(uint region, bool value) {
314 set_by_index(region, value);
315 }
316 bool is_candidate(uint region) {
317 return get_by_index(region);
318 }
319 };
320
321 HumongousReclaimCandidates _humongous_reclaim_candidates;
322 // Stores whether during humongous object registration we found candidate regions.
323 // If not, we can skip a few steps.
324 bool _has_humongous_reclaim_candidates;
325
326 volatile unsigned _gc_time_stamp;
327
328 size_t* _surviving_young_words;
329
330 G1HRPrinter _hr_printer;
331
332 void setup_surviving_young_words();
333 void update_surviving_young_words(size_t* surv_young_words);
334 void cleanup_surviving_young_words();
335
336 // It decides whether an explicit GC should start a concurrent cycle
337 // instead of doing a STW GC. Currently, a concurrent cycle is
338 // explicitly started if:
339 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
340 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
341 // (c) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent.
342 // (d) cause == _g1_humongous_allocation
343 bool should_do_concurrent_full_gc(GCCause::Cause cause);
344
345 // indicates whether we are in young or mixed GC mode
346 G1CollectorState _collector_state;
347
348 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
349 // concurrent cycles) we have started.
350 volatile uint _old_marking_cycles_started;
351
352 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
353 // concurrent cycles) we have completed.
354 volatile uint _old_marking_cycles_completed;
355
356 bool _heap_summary_sent;
357
358 // This is a non-product method that is helpful for testing. It is
359 // called at the end of a GC and artificially expands the heap by
360 // allocating a number of dead regions. This way we can induce very
361 // frequent marking cycles and stress the cleanup / concurrent
362 // cleanup code more (as all the regions that will be allocated by
363 // this method will be found dead by the marking cycle).
364 void allocate_dummy_regions() PRODUCT_RETURN;
365
366 // Clear RSets after a compaction. It also resets the GC time stamps.
367 void clear_rsets_post_compaction();
368
369 // If the HR printer is active, dump the state of the regions in the
370 // heap after a compaction.
371 void print_hrm_post_compaction();
372
373 // Create a memory mapper for auxiliary data structures of the given size and
374 // translation factor.
375 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description,
376 size_t size,
377 size_t translation_factor);
378
379 double verify(bool guard, const char* msg);
380 void verify_before_gc();
381 void verify_after_gc();
382
383 void log_gc_header();
384 void log_gc_footer(double pause_time_sec);
385
386 void trace_heap(GCWhen::Type when, const GCTracer* tracer);
387
388 // These are macros so that, if the assert fires, we get the correct
389 // line number, file, etc.
390
391 #define heap_locking_asserts_err_msg(_extra_message_) \
392 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
393 (_extra_message_), \
394 BOOL_TO_STR(Heap_lock->owned_by_self()), \
395 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
396 BOOL_TO_STR(Thread::current()->is_VM_thread()))
397
398 #define assert_heap_locked() \
399 do { \
400 assert(Heap_lock->owned_by_self(), \
401 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
402 } while (0)
403
404 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
405 do { \
406 assert(Heap_lock->owned_by_self() || \
407 (SafepointSynchronize::is_at_safepoint() && \
408 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
409 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
410 "should be at a safepoint")); \
411 } while (0)
412
413 #define assert_heap_locked_and_not_at_safepoint() \
414 do { \
415 assert(Heap_lock->owned_by_self() && \
416 !SafepointSynchronize::is_at_safepoint(), \
417 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
418 "should not be at a safepoint")); \
419 } while (0)
420
421 #define assert_heap_not_locked() \
422 do { \
423 assert(!Heap_lock->owned_by_self(), \
424 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
425 } while (0)
426
427 #define assert_heap_not_locked_and_not_at_safepoint() \
428 do { \
429 assert(!Heap_lock->owned_by_self() && \
430 !SafepointSynchronize::is_at_safepoint(), \
431 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
432 "should not be at a safepoint")); \
433 } while (0)
434
435 #define assert_at_safepoint(_should_be_vm_thread_) \
436 do { \
437 assert(SafepointSynchronize::is_at_safepoint() && \
438 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
439 heap_locking_asserts_err_msg("should be at a safepoint")); \
440 } while (0)
441
442 #define assert_not_at_safepoint() \
443 do { \
444 assert(!SafepointSynchronize::is_at_safepoint(), \
445 heap_locking_asserts_err_msg("should not be at a safepoint")); \
446 } while (0)
447
448 protected:
449
450 // The young region list.
451 YoungList* _young_list;
452
453 // The current policy object for the collector.
454 G1CollectorPolicy* _g1_policy;
455
456 // This is the second level of trying to allocate a new region. If
457 // new_region() didn't find a region on the free_list, this call will
458 // check whether there's anything available on the
459 // secondary_free_list and/or wait for more regions to appear on
460 // that list, if _free_regions_coming is set.
461 HeapRegion* new_region_try_secondary_free_list(bool is_old);
462
463 // Try to allocate a single non-humongous HeapRegion sufficient for
464 // an allocation of the given word_size. If do_expand is true,
465 // attempt to expand the heap if necessary to satisfy the allocation
466 // request. If the region is to be used as an old region or for a
467 // humongous object, set is_old to true. If not, to false.
468 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand);
469
470 // Initialize a contiguous set of free regions of length num_regions
471 // and starting at index first so that they appear as a single
472 // humongous region.
473 HeapWord* humongous_obj_allocate_initialize_regions(uint first,
474 uint num_regions,
475 size_t word_size,
476 AllocationContext_t context);
477
478 // Attempt to allocate a humongous object of the given size. Return
479 // NULL if unsuccessful.
480 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context);
481
482 // The following two methods, allocate_new_tlab() and
483 // mem_allocate(), are the two main entry points from the runtime
484 // into the G1's allocation routines. They have the following
485 // assumptions:
486 //
487 // * They should both be called outside safepoints.
488 //
489 // * They should both be called without holding the Heap_lock.
490 //
491 // * All allocation requests for new TLABs should go to
492 // allocate_new_tlab().
493 //
494 // * All non-TLAB allocation requests should go to mem_allocate().
495 //
496 // * If either call cannot satisfy the allocation request using the
497 // current allocating region, they will try to get a new one. If
498 // this fails, they will attempt to do an evacuation pause and
499 // retry the allocation.
500 //
501 // * If all allocation attempts fail, even after trying to schedule
502 // an evacuation pause, allocate_new_tlab() will return NULL,
503 // whereas mem_allocate() will attempt a heap expansion and/or
504 // schedule a Full GC.
505 //
506 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
507 // should never be called with word_size being humongous. All
508 // humongous allocation requests should go to mem_allocate() which
509 // will satisfy them with a special path.
510
511 virtual HeapWord* allocate_new_tlab(size_t word_size);
512
513 virtual HeapWord* mem_allocate(size_t word_size,
514 bool* gc_overhead_limit_was_exceeded);
515
516 // The following three methods take a gc_count_before_ret
517 // parameter which is used to return the GC count if the method
518 // returns NULL. Given that we are required to read the GC count
519 // while holding the Heap_lock, and these paths will take the
520 // Heap_lock at some point, it's easier to get them to read the GC
521 // count while holding the Heap_lock before they return NULL instead
522 // of the caller (namely: mem_allocate()) having to also take the
523 // Heap_lock just to read the GC count.
524
525 // First-level mutator allocation attempt: try to allocate out of
526 // the mutator alloc region without taking the Heap_lock. This
527 // should only be used for non-humongous allocations.
528 inline HeapWord* attempt_allocation(size_t word_size,
529 uint* gc_count_before_ret,
530 uint* gclocker_retry_count_ret);
531
532 // Second-level mutator allocation attempt: take the Heap_lock and
533 // retry the allocation attempt, potentially scheduling a GC
534 // pause. This should only be used for non-humongous allocations.
535 HeapWord* attempt_allocation_slow(size_t word_size,
536 AllocationContext_t context,
537 uint* gc_count_before_ret,
538 uint* gclocker_retry_count_ret);
539
540 // Takes the Heap_lock and attempts a humongous allocation. It can
541 // potentially schedule a GC pause.
542 HeapWord* attempt_allocation_humongous(size_t word_size,
543 uint* gc_count_before_ret,
544 uint* gclocker_retry_count_ret);
545
546 // Allocation attempt that should be called during safepoints (e.g.,
547 // at the end of a successful GC). expect_null_mutator_alloc_region
548 // specifies whether the mutator alloc region is expected to be NULL
549 // or not.
550 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
551 AllocationContext_t context,
552 bool expect_null_mutator_alloc_region);
553
554 // It dirties the cards that cover the block so that so that the post
555 // write barrier never queues anything when updating objects on this
556 // block. It is assumed (and in fact we assert) that the block
557 // belongs to a young region.
558 inline void dirty_young_block(HeapWord* start, size_t word_size);
559
560 // Allocate blocks during garbage collection. Will ensure an
561 // allocation region, either by picking one or expanding the
562 // heap, and then allocate a block of the given size. The block
563 // may not be a humongous - it must fit into a single heap region.
564 inline HeapWord* par_allocate_during_gc(InCSetState dest,
565 size_t word_size,
566 AllocationContext_t context);
567 // Ensure that no further allocations can happen in "r", bearing in mind
568 // that parallel threads might be attempting allocations.
569 void par_allocate_remaining_space(HeapRegion* r);
570
571 // Allocation attempt during GC for a survivor object / PLAB.
572 inline HeapWord* survivor_attempt_allocation(size_t word_size,
573 AllocationContext_t context);
574
575 // Allocation attempt during GC for an old object / PLAB.
576 inline HeapWord* old_attempt_allocation(size_t word_size,
577 AllocationContext_t context);
578
579 // These methods are the "callbacks" from the G1AllocRegion class.
580
581 // For mutator alloc regions.
582 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
583 void retire_mutator_alloc_region(HeapRegion* alloc_region,
584 size_t allocated_bytes);
585
586 // For GC alloc regions.
587 HeapRegion* new_gc_alloc_region(size_t word_size, uint count,
588 InCSetState dest);
589 void retire_gc_alloc_region(HeapRegion* alloc_region,
590 size_t allocated_bytes, InCSetState dest);
591
592 // Allocate the highest free region in the reserved heap. This will commit
593 // regions as necessary.
594 HeapRegion* alloc_highest_free_region();
595
596 // - if explicit_gc is true, the GC is for a System.gc() or a heap
597 // inspection request and should collect the entire heap
598 // - if clear_all_soft_refs is true, all soft references should be
599 // cleared during the GC
600 // - if explicit_gc is false, word_size describes the allocation that
601 // the GC should attempt (at least) to satisfy
602 // - it returns false if it is unable to do the collection due to the
603 // GC locker being active, true otherwise
604 bool do_collection(bool explicit_gc,
605 bool clear_all_soft_refs,
606 size_t word_size);
607
608 // Callback from VM_G1CollectFull operation.
609 // Perform a full collection.
610 virtual void do_full_collection(bool clear_all_soft_refs);
611
612 // Resize the heap if necessary after a full collection. If this is
613 // after a collect-for allocation, "word_size" is the allocation size,
614 // and will be considered part of the used portion of the heap.
615 void resize_if_necessary_after_full_collection(size_t word_size);
616
617 // Callback from VM_G1CollectForAllocation operation.
618 // This function does everything necessary/possible to satisfy a
619 // failed allocation request (including collection, expansion, etc.)
620 HeapWord* satisfy_failed_allocation(size_t word_size,
621 AllocationContext_t context,
622 bool* succeeded);
623
624 // Attempting to expand the heap sufficiently
625 // to support an allocation of the given "word_size". If
626 // successful, perform the allocation and return the address of the
627 // allocated block, or else "NULL".
628 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context);
629
630 // Process any reference objects discovered during
631 // an incremental evacuation pause.
632 void process_discovered_references();
633
634 // Enqueue any remaining discovered references
635 // after processing.
636 void enqueue_discovered_references();
637
638 public:
639 FlexibleWorkGang* workers() const { return _workers; }
640
641 G1Allocator* allocator() {
642 return _allocator;
643 }
644
645 G1MonitoringSupport* g1mm() {
646 assert(_g1mm != NULL, "should have been initialized");
647 return _g1mm;
648 }
649
650 // Expand the garbage-first heap by at least the given size (in bytes!).
651 // Returns true if the heap was expanded by the requested amount;
652 // false otherwise.
653 // (Rounds up to a HeapRegion boundary.)
654 bool expand(size_t expand_bytes);
655
656 // Returns the PLAB statistics for a given destination.
657 inline PLABStats* alloc_buffer_stats(InCSetState dest);
658
659 // Determines PLAB size for a given destination.
660 inline size_t desired_plab_sz(InCSetState dest);
661
662 inline AllocationContextStats& allocation_context_stats();
663
664 // Do anything common to GC's.
665 void gc_prologue(bool full);
666 void gc_epilogue(bool full);
667
668 // Modify the reclaim candidate set and test for presence.
669 // These are only valid for starts_humongous regions.
670 inline void set_humongous_reclaim_candidate(uint region, bool value);
671 inline bool is_humongous_reclaim_candidate(uint region);
672
673 // Remove from the reclaim candidate set. Also remove from the
674 // collection set so that later encounters avoid the slow path.
675 inline void set_humongous_is_live(oop obj);
676
677 // Register the given region to be part of the collection set.
678 inline void register_humongous_region_with_cset(uint index);
679 // Register regions with humongous objects (actually on the start region) in
680 // the in_cset_fast_test table.
681 void register_humongous_regions_with_cset();
682 // We register a region with the fast "in collection set" test. We
683 // simply set to true the array slot corresponding to this region.
684 void register_young_region_with_cset(HeapRegion* r) {
685 _in_cset_fast_test.set_in_young(r->hrm_index());
686 }
687 void register_old_region_with_cset(HeapRegion* r) {
688 _in_cset_fast_test.set_in_old(r->hrm_index());
689 }
690 void clear_in_cset(const HeapRegion* hr) {
691 _in_cset_fast_test.clear(hr);
692 }
693
694 void clear_cset_fast_test() {
695 _in_cset_fast_test.clear();
696 }
697
698 // This is called at the start of either a concurrent cycle or a Full
699 // GC to update the number of old marking cycles started.
700 void increment_old_marking_cycles_started();
701
702 // This is called at the end of either a concurrent cycle or a Full
703 // GC to update the number of old marking cycles completed. Those two
704 // can happen in a nested fashion, i.e., we start a concurrent
705 // cycle, a Full GC happens half-way through it which ends first,
706 // and then the cycle notices that a Full GC happened and ends
707 // too. The concurrent parameter is a boolean to help us do a bit
708 // tighter consistency checking in the method. If concurrent is
709 // false, the caller is the inner caller in the nesting (i.e., the
710 // Full GC). If concurrent is true, the caller is the outer caller
711 // in this nesting (i.e., the concurrent cycle). Further nesting is
712 // not currently supported. The end of this call also notifies
713 // the FullGCCount_lock in case a Java thread is waiting for a full
714 // GC to happen (e.g., it called System.gc() with
715 // +ExplicitGCInvokesConcurrent).
716 void increment_old_marking_cycles_completed(bool concurrent);
717
718 uint old_marking_cycles_completed() {
719 return _old_marking_cycles_completed;
720 }
721
722 void register_concurrent_cycle_start(const Ticks& start_time);
723 void register_concurrent_cycle_end();
724 void trace_heap_after_concurrent_cycle();
725
726 G1HRPrinter* hr_printer() { return &_hr_printer; }
727
728 // Frees a non-humongous region by initializing its contents and
729 // adding it to the free list that's passed as a parameter (this is
730 // usually a local list which will be appended to the master free
731 // list later). The used bytes of freed regions are accumulated in
732 // pre_used. If par is true, the region's RSet will not be freed
733 // up. The assumption is that this will be done later.
734 // The locked parameter indicates if the caller has already taken
735 // care of proper synchronization. This may allow some optimizations.
736 void free_region(HeapRegion* hr,
737 FreeRegionList* free_list,
738 bool par,
739 bool locked = false);
740
741 // Frees a humongous region by collapsing it into individual regions
742 // and calling free_region() for each of them. The freed regions
743 // will be added to the free list that's passed as a parameter (this
744 // is usually a local list which will be appended to the master free
745 // list later). The used bytes of freed regions are accumulated in
746 // pre_used. If par is true, the region's RSet will not be freed
747 // up. The assumption is that this will be done later.
748 void free_humongous_region(HeapRegion* hr,
749 FreeRegionList* free_list,
750 bool par);
751
752 // Facility for allocating in 'archive' regions in high heap memory and
753 // recording the allocated ranges. These should all be called from the
754 // VM thread at safepoints, without the heap lock held. They can be used
755 // to create and archive a set of heap regions which can be mapped at the
756 // same fixed addresses in a subsequent JVM invocation.
757 void begin_archive_alloc_range();
758
759 // Check if the requested size would be too large for an archive allocation.
760 bool is_archive_alloc_too_large(size_t word_size);
761
762 // Allocate memory of the requested size from the archive region. This will
763 // return NULL if the size is too large or if no memory is available. It
764 // does not trigger a garbage collection.
765 HeapWord* archive_mem_allocate(size_t word_size);
766
767 // Optionally aligns the end address and returns the allocated ranges in
768 // an array of MemRegions in order of ascending addresses.
769 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
770 size_t end_alignment_in_bytes = 0);
771
772 // Facility for allocating a fixed range within the heap and marking
773 // the containing regions as 'archive'. For use at JVM init time, when the
774 // caller may mmap archived heap data at the specified range(s).
775 // Verify that the MemRegions specified in the argument array are within the
776 // reserved heap.
777 bool check_archive_addresses(MemRegion* range, size_t count);
778
779 // Commit the appropriate G1 regions containing the specified MemRegions
780 // and mark them as 'archive' regions. The regions in the array must be
781 // non-overlapping and in order of ascending address.
782 bool alloc_archive_regions(MemRegion* range, size_t count);
783
784 // Insert any required filler objects in the G1 regions around the specified
785 // ranges to make the regions parseable. This must be called after
786 // alloc_archive_regions, and after class loading has occurred.
787 void fill_archive_regions(MemRegion* range, size_t count);
788
789 protected:
790
791 // Shrink the garbage-first heap by at most the given size (in bytes!).
792 // (Rounds down to a HeapRegion boundary.)
793 virtual void shrink(size_t expand_bytes);
794 void shrink_helper(size_t expand_bytes);
795
796 #if TASKQUEUE_STATS
797 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
798 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
799 void reset_taskqueue_stats();
800 #endif // TASKQUEUE_STATS
801
802 // Schedule the VM operation that will do an evacuation pause to
803 // satisfy an allocation request of word_size. *succeeded will
804 // return whether the VM operation was successful (it did do an
805 // evacuation pause) or not (another thread beat us to it or the GC
806 // locker was active). Given that we should not be holding the
807 // Heap_lock when we enter this method, we will pass the
808 // gc_count_before (i.e., total_collections()) as a parameter since
809 // it has to be read while holding the Heap_lock. Currently, both
810 // methods that call do_collection_pause() release the Heap_lock
811 // before the call, so it's easy to read gc_count_before just before.
812 HeapWord* do_collection_pause(size_t word_size,
813 uint gc_count_before,
814 bool* succeeded,
815 GCCause::Cause gc_cause);
816
817 void wait_for_root_region_scanning();
818
819 // The guts of the incremental collection pause, executed by the vm
820 // thread. It returns false if it is unable to do the collection due
821 // to the GC locker being active, true otherwise
822 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
823
824 // Actually do the work of evacuating the collection set.
825 void evacuate_collection_set(EvacuationInfo& evacuation_info);
826
827 // The g1 remembered set of the heap.
828 G1RemSet* _g1_rem_set;
829
830 // A set of cards that cover the objects for which the Rsets should be updated
831 // concurrently after the collection.
832 DirtyCardQueueSet _dirty_card_queue_set;
833
834 // The closure used to refine a single card.
835 RefineCardTableEntryClosure* _refine_cte_cl;
836
837 // A DirtyCardQueueSet that is used to hold cards that contain
838 // references into the current collection set. This is used to
839 // update the remembered sets of the regions in the collection
840 // set in the event of an evacuation failure.
841 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
842
843 // After a collection pause, make the regions in the CS into free
844 // regions.
845 void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info);
846
847 // Abandon the current collection set without recording policy
848 // statistics or updating free lists.
849 void abandon_collection_set(HeapRegion* cs_head);
850
851 // The concurrent marker (and the thread it runs in.)
852 ConcurrentMark* _cm;
853 ConcurrentMarkThread* _cmThread;
854
855 // The concurrent refiner.
856 ConcurrentG1Refine* _cg1r;
857
858 // The parallel task queues
859 RefToScanQueueSet *_task_queues;
860
861 // True iff a evacuation has failed in the current collection.
862 bool _evacuation_failed;
863
864 EvacuationFailedInfo* _evacuation_failed_info_array;
865
866 // Failed evacuations cause some logical from-space objects to have
867 // forwarding pointers to themselves. Reset them.
868 void remove_self_forwarding_pointers();
869
870 // Together, these store an object with a preserved mark, and its mark value.
871 Stack<oop, mtGC> _objs_with_preserved_marks;
872 Stack<markOop, mtGC> _preserved_marks_of_objs;
873
874 // Preserve the mark of "obj", if necessary, in preparation for its mark
875 // word being overwritten with a self-forwarding-pointer.
876 void preserve_mark_if_necessary(oop obj, markOop m);
877
878 // The stack of evac-failure objects left to be scanned.
879 GrowableArray<oop>* _evac_failure_scan_stack;
880 // The closure to apply to evac-failure objects.
881
882 OopsInHeapRegionClosure* _evac_failure_closure;
883 // Set the field above.
884 void
885 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
886 _evac_failure_closure = evac_failure_closure;
887 }
888
889 // Push "obj" on the scan stack.
890 void push_on_evac_failure_scan_stack(oop obj);
891 // Process scan stack entries until the stack is empty.
892 void drain_evac_failure_scan_stack();
893 // True iff an invocation of "drain_scan_stack" is in progress; to
894 // prevent unnecessary recursion.
895 bool _drain_in_progress;
896
897 // Do any necessary initialization for evacuation-failure handling.
898 // "cl" is the closure that will be used to process evac-failure
899 // objects.
900 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
901 // Do any necessary cleanup for evacuation-failure handling data
902 // structures.
903 void finalize_for_evac_failure();
904
905 // An attempt to evacuate "obj" has failed; take necessary steps.
906 oop handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, oop obj);
907 void handle_evacuation_failure_common(oop obj, markOop m);
908
909 #ifndef PRODUCT
910 // Support for forcing evacuation failures. Analogous to
911 // PromotionFailureALot for the other collectors.
912
913 // Records whether G1EvacuationFailureALot should be in effect
914 // for the current GC
915 bool _evacuation_failure_alot_for_current_gc;
916
917 // Used to record the GC number for interval checking when
918 // determining whether G1EvaucationFailureALot is in effect
919 // for the current GC.
920 size_t _evacuation_failure_alot_gc_number;
921
922 // Count of the number of evacuations between failures.
923 volatile size_t _evacuation_failure_alot_count;
924
925 // Set whether G1EvacuationFailureALot should be in effect
926 // for the current GC (based upon the type of GC and which
927 // command line flags are set);
928 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young,
929 bool during_initial_mark,
930 bool during_marking);
931
932 inline void set_evacuation_failure_alot_for_current_gc();
933
934 // Return true if it's time to cause an evacuation failure.
935 inline bool evacuation_should_fail();
936
937 // Reset the G1EvacuationFailureALot counters. Should be called at
938 // the end of an evacuation pause in which an evacuation failure occurred.
939 inline void reset_evacuation_should_fail();
940 #endif // !PRODUCT
941
942 // ("Weak") Reference processing support.
943 //
944 // G1 has 2 instances of the reference processor class. One
945 // (_ref_processor_cm) handles reference object discovery
946 // and subsequent processing during concurrent marking cycles.
947 //
948 // The other (_ref_processor_stw) handles reference object
949 // discovery and processing during full GCs and incremental
950 // evacuation pauses.
951 //
952 // During an incremental pause, reference discovery will be
953 // temporarily disabled for _ref_processor_cm and will be
954 // enabled for _ref_processor_stw. At the end of the evacuation
955 // pause references discovered by _ref_processor_stw will be
956 // processed and discovery will be disabled. The previous
957 // setting for reference object discovery for _ref_processor_cm
958 // will be re-instated.
959 //
960 // At the start of marking:
961 // * Discovery by the CM ref processor is verified to be inactive
962 // and it's discovered lists are empty.
963 // * Discovery by the CM ref processor is then enabled.
964 //
965 // At the end of marking:
966 // * Any references on the CM ref processor's discovered
967 // lists are processed (possibly MT).
968 //
969 // At the start of full GC we:
970 // * Disable discovery by the CM ref processor and
971 // empty CM ref processor's discovered lists
972 // (without processing any entries).
973 // * Verify that the STW ref processor is inactive and it's
974 // discovered lists are empty.
975 // * Temporarily set STW ref processor discovery as single threaded.
976 // * Temporarily clear the STW ref processor's _is_alive_non_header
977 // field.
978 // * Finally enable discovery by the STW ref processor.
979 //
980 // The STW ref processor is used to record any discovered
981 // references during the full GC.
982 //
983 // At the end of a full GC we:
984 // * Enqueue any reference objects discovered by the STW ref processor
985 // that have non-live referents. This has the side-effect of
986 // making the STW ref processor inactive by disabling discovery.
987 // * Verify that the CM ref processor is still inactive
988 // and no references have been placed on it's discovered
989 // lists (also checked as a precondition during initial marking).
990
991 // The (stw) reference processor...
992 ReferenceProcessor* _ref_processor_stw;
993
994 STWGCTimer* _gc_timer_stw;
995 ConcurrentGCTimer* _gc_timer_cm;
996
997 G1OldTracer* _gc_tracer_cm;
998 G1NewTracer* _gc_tracer_stw;
999
1000 // During reference object discovery, the _is_alive_non_header
1001 // closure (if non-null) is applied to the referent object to
1002 // determine whether the referent is live. If so then the
1003 // reference object does not need to be 'discovered' and can
1004 // be treated as a regular oop. This has the benefit of reducing
1005 // the number of 'discovered' reference objects that need to
1006 // be processed.
1007 //
1008 // Instance of the is_alive closure for embedding into the
1009 // STW reference processor as the _is_alive_non_header field.
1010 // Supplying a value for the _is_alive_non_header field is
1011 // optional but doing so prevents unnecessary additions to
1012 // the discovered lists during reference discovery.
1013 G1STWIsAliveClosure _is_alive_closure_stw;
1014
1015 // The (concurrent marking) reference processor...
1016 ReferenceProcessor* _ref_processor_cm;
1017
1018 // Instance of the concurrent mark is_alive closure for embedding
1019 // into the Concurrent Marking reference processor as the
1020 // _is_alive_non_header field. Supplying a value for the
1021 // _is_alive_non_header field is optional but doing so prevents
1022 // unnecessary additions to the discovered lists during reference
1023 // discovery.
1024 G1CMIsAliveClosure _is_alive_closure_cm;
1025
1026 // Cache used by G1CollectedHeap::start_cset_region_for_worker().
1027 HeapRegion** _worker_cset_start_region;
1028
1029 // Time stamp to validate the regions recorded in the cache
1030 // used by G1CollectedHeap::start_cset_region_for_worker().
1031 // The heap region entry for a given worker is valid iff
1032 // the associated time stamp value matches the current value
1033 // of G1CollectedHeap::_gc_time_stamp.
1034 uint* _worker_cset_start_region_time_stamp;
1035
1036 volatile bool _free_regions_coming;
1037
1038 public:
1039
1040 void set_refine_cte_cl_concurrency(bool concurrent);
1041
1042 RefToScanQueue *task_queue(uint i) const;
1043
1044 uint num_task_queues() const;
1045
1046 // A set of cards where updates happened during the GC
1047 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
1048
1049 // A DirtyCardQueueSet that is used to hold cards that contain
1050 // references into the current collection set. This is used to
1051 // update the remembered sets of the regions in the collection
1052 // set in the event of an evacuation failure.
1053 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
1054 { return _into_cset_dirty_card_queue_set; }
1055
1056 // Create a G1CollectedHeap with the specified policy.
1057 // Must call the initialize method afterwards.
1058 // May not return if something goes wrong.
1059 G1CollectedHeap(G1CollectorPolicy* policy);
1060
1061 // Initialize the G1CollectedHeap to have the initial and
1062 // maximum sizes and remembered and barrier sets
1063 // specified by the policy object.
1064 jint initialize();
1065
1066 virtual void stop();
1067
1068 // Return the (conservative) maximum heap alignment for any G1 heap
1069 static size_t conservative_max_heap_alignment();
1070
1071 // Does operations required after initialization has been done.
1072 void post_initialize();
1073
1074 // Initialize weak reference processing.
1075 void ref_processing_init();
1076
1077 virtual Name kind() const {
1078 return CollectedHeap::G1CollectedHeap;
1079 }
1080
1081 G1CollectorState* collector_state() { return &_collector_state; }
1082
1083 // The current policy object for the collector.
1084 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
1085
1086 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); }
1087
1088 // Adaptive size policy. No such thing for g1.
1089 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
1090
1091 // The rem set and barrier set.
1092 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
1093
1094 unsigned get_gc_time_stamp() {
1095 return _gc_time_stamp;
1096 }
1097
1098 inline void reset_gc_time_stamp();
1099
1100 void check_gc_time_stamps() PRODUCT_RETURN;
1101
1102 inline void increment_gc_time_stamp();
1103
1104 // Reset the given region's GC timestamp. If it's starts humongous,
1105 // also reset the GC timestamp of its corresponding
1106 // continues humongous regions too.
1107 void reset_gc_time_stamps(HeapRegion* hr);
1108
1109 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
1110 DirtyCardQueue* into_cset_dcq,
1111 bool concurrent, uint worker_i);
1112
1113 // The shared block offset table array.
1114 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
1115
1116 // Reference Processing accessors
1117
1118 // The STW reference processor....
1119 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1120
1121 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; }
1122
1123 // The Concurrent Marking reference processor...
1124 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1125
1126 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; }
1127 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; }
1128
1129 virtual size_t capacity() const;
1130 virtual size_t used() const;
1131 // This should be called when we're not holding the heap lock. The
1132 // result might be a bit inaccurate.
1133 size_t used_unlocked() const;
1134 size_t recalculate_used() const;
1135
1136 // These virtual functions do the actual allocation.
1137 // Some heaps may offer a contiguous region for shared non-blocking
1138 // allocation, via inlined code (by exporting the address of the top and
1139 // end fields defining the extent of the contiguous allocation region.)
1140 // But G1CollectedHeap doesn't yet support this.
1141
1142 virtual bool is_maximal_no_gc() const {
1143 return _hrm.available() == 0;
1144 }
1145
1146 // The current number of regions in the heap.
1147 uint num_regions() const { return _hrm.length(); }
1148
1149 // The max number of regions in the heap.
1150 uint max_regions() const { return _hrm.max_length(); }
1151
1152 // The number of regions that are completely free.
1153 uint num_free_regions() const { return _hrm.num_free_regions(); }
1154
1155 MemoryUsage get_auxiliary_data_memory_usage() const {
1156 return _hrm.get_auxiliary_data_memory_usage();
1157 }
1158
1159 // The number of regions that are not completely free.
1160 uint num_used_regions() const { return num_regions() - num_free_regions(); }
1161
1162 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1163 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1164 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
1165 void verify_dirty_young_regions() PRODUCT_RETURN;
1166
1167 #ifndef PRODUCT
1168 // Make sure that the given bitmap has no marked objects in the
1169 // range [from,limit). If it does, print an error message and return
1170 // false. Otherwise, just return true. bitmap_name should be "prev"
1171 // or "next".
1172 bool verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
1173 HeapWord* from, HeapWord* limit);
1174
1175 // Verify that the prev / next bitmap range [tams,end) for the given
1176 // region has no marks. Return true if all is well, false if errors
1177 // are detected.
1178 bool verify_bitmaps(const char* caller, HeapRegion* hr);
1179 #endif // PRODUCT
1180
1181 // If G1VerifyBitmaps is set, verify that the marking bitmaps for
1182 // the given region do not have any spurious marks. If errors are
1183 // detected, print appropriate error messages and crash.
1184 void check_bitmaps(const char* caller, HeapRegion* hr) PRODUCT_RETURN;
1185
1186 // If G1VerifyBitmaps is set, verify that the marking bitmaps do not
1187 // have any spurious marks. If errors are detected, print
1188 // appropriate error messages and crash.
1189 void check_bitmaps(const char* caller) PRODUCT_RETURN;
1190
1191 // Do sanity check on the contents of the in-cset fast test table.
1192 bool check_cset_fast_test() PRODUCT_RETURN_( return true; );
1193
1194 // verify_region_sets() performs verification over the region
1195 // lists. It will be compiled in the product code to be used when
1196 // necessary (i.e., during heap verification).
1197 void verify_region_sets();
1198
1199 // verify_region_sets_optional() is planted in the code for
1200 // list verification in non-product builds (and it can be enabled in
1201 // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1).
1202 #if HEAP_REGION_SET_FORCE_VERIFY
1203 void verify_region_sets_optional() {
1204 verify_region_sets();
1205 }
1206 #else // HEAP_REGION_SET_FORCE_VERIFY
1207 void verify_region_sets_optional() { }
1208 #endif // HEAP_REGION_SET_FORCE_VERIFY
1209
1210 #ifdef ASSERT
1211 bool is_on_master_free_list(HeapRegion* hr) {
1212 return _hrm.is_free(hr);
1213 }
1214 #endif // ASSERT
1215
1216 // Wrapper for the region list operations that can be called from
1217 // methods outside this class.
1218
1219 void secondary_free_list_add(FreeRegionList* list) {
1220 _secondary_free_list.add_ordered(list);
1221 }
1222
1223 void append_secondary_free_list() {
1224 _hrm.insert_list_into_free_list(&_secondary_free_list);
1225 }
1226
1227 void append_secondary_free_list_if_not_empty_with_lock() {
1228 // If the secondary free list looks empty there's no reason to
1229 // take the lock and then try to append it.
1230 if (!_secondary_free_list.is_empty()) {
1231 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1232 append_secondary_free_list();
1233 }
1234 }
1235
1236 inline void old_set_remove(HeapRegion* hr);
1237
1238 size_t non_young_capacity_bytes() {
1239 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes();
1240 }
1241
1242 void set_free_regions_coming();
1243 void reset_free_regions_coming();
1244 bool free_regions_coming() { return _free_regions_coming; }
1245 void wait_while_free_regions_coming();
1246
1247 // Determine whether the given region is one that we are using as an
1248 // old GC alloc region.
1249 bool is_old_gc_alloc_region(HeapRegion* hr) {
1250 return _allocator->is_retained_old_region(hr);
1251 }
1252
1253 // Perform a collection of the heap; intended for use in implementing
1254 // "System.gc". This probably implies as full a collection as the
1255 // "CollectedHeap" supports.
1256 virtual void collect(GCCause::Cause cause);
1257
1258 // The same as above but assume that the caller holds the Heap_lock.
1259 void collect_locked(GCCause::Cause cause);
1260
1261 virtual bool copy_allocation_context_stats(const jint* contexts,
1262 jlong* totals,
1263 jbyte* accuracy,
1264 jint len);
1265
1266 // True iff an evacuation has failed in the most-recent collection.
1267 bool evacuation_failed() { return _evacuation_failed; }
1268
1269 void remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, const HeapRegionSetCount& humongous_regions_removed);
1270 void prepend_to_freelist(FreeRegionList* list);
1271 void decrement_summary_bytes(size_t bytes);
1272
1273 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1274 virtual bool is_in(const void* p) const;
1275 #ifdef ASSERT
1276 // Returns whether p is in one of the available areas of the heap. Slow but
1277 // extensive version.
1278 bool is_in_exact(const void* p) const;
1279 #endif
1280
1281 // Return "TRUE" iff the given object address is within the collection
1282 // set. Slow implementation.
1283 inline bool obj_in_cs(oop obj);
1284
1285 inline bool is_in_cset(const HeapRegion *hr);
1286 inline bool is_in_cset(oop obj);
1287
1288 inline bool is_in_cset_or_humongous(const oop obj);
1289
1290 private:
1291 // This array is used for a quick test on whether a reference points into
1292 // the collection set or not. Each of the array's elements denotes whether the
1293 // corresponding region is in the collection set or not.
1294 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test;
1295
1296 public:
1297
1298 inline InCSetState in_cset_state(const oop obj);
1299
1300 // Return "TRUE" iff the given object address is in the reserved
1301 // region of g1.
1302 bool is_in_g1_reserved(const void* p) const {
1303 return _hrm.reserved().contains(p);
1304 }
1305
1306 // Returns a MemRegion that corresponds to the space that has been
1307 // reserved for the heap
1308 MemRegion g1_reserved() const {
1309 return _hrm.reserved();
1310 }
1311
1312 virtual bool is_in_closed_subset(const void* p) const;
1313
1314 G1SATBCardTableLoggingModRefBS* g1_barrier_set() {
1315 return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set());
1316 }
1317
1318 // This resets the card table to all zeros. It is used after
1319 // a collection pause which used the card table to claim cards.
1320 void cleanUpCardTable();
1321
1322 // Iteration functions.
1323
1324 // Iterate over all objects, calling "cl.do_object" on each.
1325 virtual void object_iterate(ObjectClosure* cl);
1326
1327 virtual void safe_object_iterate(ObjectClosure* cl) {
1328 object_iterate(cl);
1329 }
1330
1331 // Iterate over heap regions, in address order, terminating the
1332 // iteration early if the "doHeapRegion" method returns "true".
1333 void heap_region_iterate(HeapRegionClosure* blk) const;
1334
1335 // Return the region with the given index. It assumes the index is valid.
1336 inline HeapRegion* region_at(uint index) const;
1337
1338 // Calculate the region index of the given address. Given address must be
1339 // within the heap.
1340 inline uint addr_to_region(HeapWord* addr) const;
1341
1342 inline HeapWord* bottom_addr_for_region(uint index) const;
1343
1344 // Iterate over the heap regions in parallel. Assumes that this will be called
1345 // in parallel by ParallelGCThreads worker threads with distinct worker ids
1346 // in the range [0..max(ParallelGCThreads-1, 1)]. Applies "blk->doHeapRegion"
1347 // to each of the regions, by attempting to claim the region using the
1348 // HeapRegionClaimer and, if successful, applying the closure to the claimed
1349 // region. The concurrent argument should be set to true if iteration is
1350 // performed concurrently, during which no assumptions are made for consistent
1351 // attributes of the heap regions (as they might be modified while iterating).
1352 void heap_region_par_iterate(HeapRegionClosure* cl,
1353 uint worker_id,
1354 HeapRegionClaimer* hrclaimer,
1355 bool concurrent = false) const;
1356
1357 // Clear the cached cset start regions and (more importantly)
1358 // the time stamps. Called when we reset the GC time stamp.
1359 void clear_cset_start_regions();
1360
1361 // Given the id of a worker, obtain or calculate a suitable
1362 // starting region for iterating over the current collection set.
1363 HeapRegion* start_cset_region_for_worker(uint worker_i);
1364
1365 // Iterate over the regions (if any) in the current collection set.
1366 void collection_set_iterate(HeapRegionClosure* blk);
1367
1368 // As above but starting from region r
1369 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1370
1371 HeapRegion* next_compaction_region(const HeapRegion* from) const;
1372
1373 // Returns the HeapRegion that contains addr. addr must not be NULL.
1374 template <class T>
1375 inline HeapRegion* heap_region_containing_raw(const T addr) const;
1376
1377 // Returns the HeapRegion that contains addr. addr must not be NULL.
1378 // If addr is within a humongous continues region, it returns its humongous start region.
1379 template <class T>
1380 inline HeapRegion* heap_region_containing(const T addr) const;
1381
1382 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1383 // each address in the (reserved) heap is a member of exactly
1384 // one block. The defining characteristic of a block is that it is
1385 // possible to find its size, and thus to progress forward to the next
1386 // block. (Blocks may be of different sizes.) Thus, blocks may
1387 // represent Java objects, or they might be free blocks in a
1388 // free-list-based heap (or subheap), as long as the two kinds are
1389 // distinguishable and the size of each is determinable.
1390
1391 // Returns the address of the start of the "block" that contains the
1392 // address "addr". We say "blocks" instead of "object" since some heaps
1393 // may not pack objects densely; a chunk may either be an object or a
1394 // non-object.
1395 virtual HeapWord* block_start(const void* addr) const;
1396
1397 // Requires "addr" to be the start of a chunk, and returns its size.
1398 // "addr + size" is required to be the start of a new chunk, or the end
1399 // of the active area of the heap.
1400 virtual size_t block_size(const HeapWord* addr) const;
1401
1402 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1403 // the block is an object.
1404 virtual bool block_is_obj(const HeapWord* addr) const;
1405
1406 // Section on thread-local allocation buffers (TLABs)
1407 // See CollectedHeap for semantics.
1408
1409 bool supports_tlab_allocation() const;
1410 size_t tlab_capacity(Thread* ignored) const;
1411 size_t tlab_used(Thread* ignored) const;
1412 size_t max_tlab_size() const;
1413 size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1414
1415 // Can a compiler initialize a new object without store barriers?
1416 // This permission only extends from the creation of a new object
1417 // via a TLAB up to the first subsequent safepoint. If such permission
1418 // is granted for this heap type, the compiler promises to call
1419 // defer_store_barrier() below on any slow path allocation of
1420 // a new object for which such initializing store barriers will
1421 // have been elided. G1, like CMS, allows this, but should be
1422 // ready to provide a compensating write barrier as necessary
1423 // if that storage came out of a non-young region. The efficiency
1424 // of this implementation depends crucially on being able to
1425 // answer very efficiently in constant time whether a piece of
1426 // storage in the heap comes from a young region or not.
1427 // See ReduceInitialCardMarks.
1428 virtual bool can_elide_tlab_store_barriers() const {
1429 return true;
1430 }
1431
1432 virtual bool card_mark_must_follow_store() const {
1433 return true;
1434 }
1435
1436 inline bool is_in_young(const oop obj);
1437
1438 virtual bool is_scavengable(const void* addr);
1439
1440 // We don't need barriers for initializing stores to objects
1441 // in the young gen: for the SATB pre-barrier, there is no
1442 // pre-value that needs to be remembered; for the remembered-set
1443 // update logging post-barrier, we don't maintain remembered set
1444 // information for young gen objects.
1445 virtual inline bool can_elide_initializing_store_barrier(oop new_obj);
1446
1447 // Returns "true" iff the given word_size is "very large".
1448 static bool is_humongous(size_t word_size) {
1449 // Note this has to be strictly greater-than as the TLABs
1450 // are capped at the humongous threshold and we want to
1451 // ensure that we don't try to allocate a TLAB as
1452 // humongous and that we don't allocate a humongous
1453 // object in a TLAB.
1454 return word_size > _humongous_object_threshold_in_words;
1455 }
1456
1457 // Returns the humongous threshold for a specific region size
1458 static size_t humongous_threshold_for(size_t region_size) {
1459 return (region_size / 2);
1460 }
1461
1462 // Update mod union table with the set of dirty cards.
1463 void updateModUnion();
1464
1465 // Set the mod union bits corresponding to the given memRegion. Note
1466 // that this is always a safe operation, since it doesn't clear any
1467 // bits.
1468 void markModUnionRange(MemRegion mr);
1469
1470 // Print the maximum heap capacity.
1471 virtual size_t max_capacity() const;
1472
1473 virtual jlong millis_since_last_gc();
1474
1475
1476 // Convenience function to be used in situations where the heap type can be
1477 // asserted to be this type.
1478 static G1CollectedHeap* heap();
1479
1480 void set_region_short_lived_locked(HeapRegion* hr);
1481 // add appropriate methods for any other surv rate groups
1482
1483 YoungList* young_list() const { return _young_list; }
1484
1485 // debugging
1486 bool check_young_list_well_formed() {
1487 return _young_list->check_list_well_formed();
1488 }
1489
1490 bool check_young_list_empty(bool check_heap,
1491 bool check_sample = true);
1492
1493 // *** Stuff related to concurrent marking. It's not clear to me that so
1494 // many of these need to be public.
1495
1496 // The functions below are helper functions that a subclass of
1497 // "CollectedHeap" can use in the implementation of its virtual
1498 // functions.
1499 // This performs a concurrent marking of the live objects in a
1500 // bitmap off to the side.
1501 void doConcurrentMark();
1502
1503 bool isMarkedPrev(oop obj) const;
1504 bool isMarkedNext(oop obj) const;
1505
1506 // Determine if an object is dead, given the object and also
1507 // the region to which the object belongs. An object is dead
1508 // iff a) it was not allocated since the last mark, b) it
1509 // is not marked, and c) it is not in an archive region.
1510 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1511 return
1512 !hr->obj_allocated_since_prev_marking(obj) &&
1513 !isMarkedPrev(obj) &&
1514 !hr->is_archive();
1515 }
1516
1517 // This function returns true when an object has been
1518 // around since the previous marking and hasn't yet
1519 // been marked during this marking, and is not in an archive region.
1520 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1521 return
1522 !hr->obj_allocated_since_next_marking(obj) &&
1523 !isMarkedNext(obj) &&
1524 !hr->is_archive();
1525 }
1526
1527 // Determine if an object is dead, given only the object itself.
1528 // This will find the region to which the object belongs and
1529 // then call the region version of the same function.
1530
1531 // Added if it is NULL it isn't dead.
1532
1533 inline bool is_obj_dead(const oop obj) const;
1534
1535 inline bool is_obj_ill(const oop obj) const;
1536
1537 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo);
1538 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo);
1539 bool is_marked(oop obj, VerifyOption vo);
1540 const char* top_at_mark_start_str(VerifyOption vo);
1541
1542 ConcurrentMark* concurrent_mark() const { return _cm; }
1543
1544 // Refinement
1545
1546 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1547
1548 // The dirty cards region list is used to record a subset of regions
1549 // whose cards need clearing. The list if populated during the
1550 // remembered set scanning and drained during the card table
1551 // cleanup. Although the methods are reentrant, population/draining
1552 // phases must not overlap. For synchronization purposes the last
1553 // element on the list points to itself.
1554 HeapRegion* _dirty_cards_region_list;
1555 void push_dirty_cards_region(HeapRegion* hr);
1556 HeapRegion* pop_dirty_cards_region();
1557
1558 // Optimized nmethod scanning support routines
1559
1560 // Register the given nmethod with the G1 heap.
1561 virtual void register_nmethod(nmethod* nm);
1562
1563 // Unregister the given nmethod from the G1 heap.
1564 virtual void unregister_nmethod(nmethod* nm);
1565
1566 // Free up superfluous code root memory.
1567 void purge_code_root_memory();
1568
1569 // Rebuild the strong code root lists for each region
1570 // after a full GC.
1571 void rebuild_strong_code_roots();
1572
1573 // Delete entries for dead interned string and clean up unreferenced symbols
1574 // in symbol table, possibly in parallel.
1575 void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true);
1576
1577 // Parallel phase of unloading/cleaning after G1 concurrent mark.
1578 void parallel_cleaning(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool class_unloading_occurred);
1579
1580 // Redirty logged cards in the refinement queue.
1581 void redirty_logged_cards();
1582 // Verification
1583
1584 // Perform any cleanup actions necessary before allowing a verification.
1585 virtual void prepare_for_verify();
1586
1587 // Perform verification.
1588
1589 // vo == UsePrevMarking -> use "prev" marking information,
1590 // vo == UseNextMarking -> use "next" marking information
1591 // vo == UseMarkWord -> use the mark word in the object header
1592 //
1593 // NOTE: Only the "prev" marking information is guaranteed to be
1594 // consistent most of the time, so most calls to this should use
1595 // vo == UsePrevMarking.
1596 // Currently, there is only one case where this is called with
1597 // vo == UseNextMarking, which is to verify the "next" marking
1598 // information at the end of remark.
1599 // Currently there is only one place where this is called with
1600 // vo == UseMarkWord, which is to verify the marking during a
1601 // full GC.
1602 void verify(bool silent, VerifyOption vo);
1603
1604 // Override; it uses the "prev" marking information
1605 virtual void verify(bool silent);
1606
1607 // The methods below are here for convenience and dispatch the
1608 // appropriate method depending on value of the given VerifyOption
1609 // parameter. The values for that parameter, and their meanings,
1610 // are the same as those above.
1611
1612 bool is_obj_dead_cond(const oop obj,
1613 const HeapRegion* hr,
1614 const VerifyOption vo) const;
1615
1616 bool is_obj_dead_cond(const oop obj,
1617 const VerifyOption vo) const;
1618
1619 G1HeapSummary create_g1_heap_summary();
1620
1621 // Printing
1622
1623 virtual void print_on(outputStream* st) const;
1624 virtual void print_extended_on(outputStream* st) const;
1625 virtual void print_on_error(outputStream* st) const;
1626
1627 virtual void print_gc_threads_on(outputStream* st) const;
1628 virtual void gc_threads_do(ThreadClosure* tc) const;
1629
1630 // Override
1631 void print_tracing_info() const;
1632
1633 // The following two methods are helpful for debugging RSet issues.
1634 void print_cset_rsets() PRODUCT_RETURN;
1635 void print_all_rsets() PRODUCT_RETURN;
1636
1637 public:
1638 size_t pending_card_num();
1639 size_t cards_scanned();
1640
1641 protected:
1642 size_t _max_heap_capacity;
1643 };
1644
1645 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP