1 /*
2 * Copyright (c) 2001, 2014, 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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7 * published by the Free Software Foundation.
8 *
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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_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP
27
28 #include "gc_implementation/g1/g1AllocationContext.hpp"
29 #include "gc_implementation/g1/g1Allocator.hpp"
30 #include "gc_implementation/g1/concurrentMark.hpp"
31 #include "gc_implementation/g1/evacuationInfo.hpp"
32 #include "gc_implementation/g1/g1AllocRegion.hpp"
33 #include "gc_implementation/g1/g1BiasedArray.hpp"
34 #include "gc_implementation/g1/g1HRPrinter.hpp"
35 #include "gc_implementation/g1/g1InCSetState.hpp"
36 #include "gc_implementation/g1/g1MonitoringSupport.hpp"
37 #include "gc_implementation/g1/g1SATBCardTableModRefBS.hpp"
38 #include "gc_implementation/g1/g1YCTypes.hpp"
39 #include "gc_implementation/g1/heapRegionManager.hpp"
40 #include "gc_implementation/g1/heapRegionSet.hpp"
41 #include "gc_implementation/shared/hSpaceCounters.hpp"
42 #include "gc_implementation/shared/parGCAllocBuffer.hpp"
43 #include "memory/barrierSet.hpp"
44 #include "memory/memRegion.hpp"
45 #include "memory/sharedHeap.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 G1ScanHeapEvacClosure;
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
80 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue;
81 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
82
83 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
84 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
85
86 class YoungList : public CHeapObj<mtGC> {
87 private:
88 G1CollectedHeap* _g1h;
89
90 HeapRegion* _head;
91
92 HeapRegion* _survivor_head;
93 HeapRegion* _survivor_tail;
94
95 HeapRegion* _curr;
96
97 uint _length;
98 uint _survivor_length;
99
100 size_t _last_sampled_rs_lengths;
101 size_t _sampled_rs_lengths;
102
103 void empty_list(HeapRegion* list);
104
105 public:
106 YoungList(G1CollectedHeap* g1h);
107
108 void push_region(HeapRegion* hr);
109 void add_survivor_region(HeapRegion* hr);
110
111 void empty_list();
112 bool is_empty() { return _length == 0; }
113 uint length() { return _length; }
114 uint survivor_length() { return _survivor_length; }
115
116 // Currently we do not keep track of the used byte sum for the
117 // young list and the survivors and it'd be quite a lot of work to
118 // do so. When we'll eventually replace the young list with
119 // instances of HeapRegionLinkedList we'll get that for free. So,
120 // we'll report the more accurate information then.
121 size_t eden_used_bytes() {
122 assert(length() >= survivor_length(), "invariant");
123 return (size_t) (length() - survivor_length()) * HeapRegion::GrainBytes;
124 }
125 size_t survivor_used_bytes() {
126 return (size_t) survivor_length() * HeapRegion::GrainBytes;
127 }
128
129 void rs_length_sampling_init();
130 bool rs_length_sampling_more();
131 void rs_length_sampling_next();
132
133 void reset_sampled_info() {
134 _last_sampled_rs_lengths = 0;
135 }
136 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }
137
138 // for development purposes
139 void reset_auxilary_lists();
140 void clear() { _head = NULL; _length = 0; }
141
142 void clear_survivors() {
143 _survivor_head = NULL;
144 _survivor_tail = NULL;
145 _survivor_length = 0;
146 }
147
148 HeapRegion* first_region() { return _head; }
149 HeapRegion* first_survivor_region() { return _survivor_head; }
150 HeapRegion* last_survivor_region() { return _survivor_tail; }
151
152 // debugging
153 bool check_list_well_formed();
154 bool check_list_empty(bool check_sample = true);
155 void print();
156 };
157
158 // The G1 STW is alive closure.
159 // An instance is embedded into the G1CH and used as the
160 // (optional) _is_alive_non_header closure in the STW
161 // reference processor. It is also extensively used during
162 // reference processing during STW evacuation pauses.
163 class G1STWIsAliveClosure: public BoolObjectClosure {
164 G1CollectedHeap* _g1;
165 public:
166 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
167 bool do_object_b(oop p);
168 };
169
170 class RefineCardTableEntryClosure;
171
172 class G1RegionMappingChangedListener : public G1MappingChangedListener {
173 private:
174 void reset_from_card_cache(uint start_idx, size_t num_regions);
175 public:
176 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
177 };
178
179 class G1CollectedHeap : public SharedHeap {
180 friend class VM_CollectForMetadataAllocation;
181 friend class VM_G1CollectForAllocation;
182 friend class VM_G1CollectFull;
183 friend class VM_G1IncCollectionPause;
184 friend class VMStructs;
185 friend class MutatorAllocRegion;
186 friend class SurvivorGCAllocRegion;
187 friend class OldGCAllocRegion;
188 friend class G1Allocator;
189 friend class G1DefaultAllocator;
190 friend class G1ResManAllocator;
191
192 // Closures used in implementation.
193 template <G1Barrier barrier, G1Mark do_mark_object>
194 friend class G1ParCopyClosure;
195 friend class G1IsAliveClosure;
196 friend class G1EvacuateFollowersClosure;
197 friend class G1ParScanThreadState;
198 friend class G1ParScanClosureSuper;
199 friend class G1ParEvacuateFollowersClosure;
200 friend class G1ParTask;
201 friend class G1ParGCAllocator;
202 friend class G1DefaultParGCAllocator;
203 friend class G1FreeGarbageRegionClosure;
204 friend class RefineCardTableEntryClosure;
205 friend class G1PrepareCompactClosure;
206 friend class RegionSorter;
207 friend class RegionResetter;
208 friend class CountRCClosure;
209 friend class EvacPopObjClosure;
210 friend class G1ParCleanupCTTask;
211
212 friend class G1FreeHumongousRegionClosure;
213 // Other related classes.
214 friend class G1MarkSweep;
215
216 private:
217 // The one and only G1CollectedHeap, so static functions can find it.
218 static G1CollectedHeap* _g1h;
219
220 static size_t _humongous_object_threshold_in_words;
221
222 // The secondary free list which contains regions that have been
223 // freed up during the cleanup process. This will be appended to
224 // the master free list when appropriate.
225 FreeRegionList _secondary_free_list;
226
227 // It keeps track of the old regions.
228 HeapRegionSet _old_set;
229
230 // It keeps track of the humongous regions.
231 HeapRegionSet _humongous_set;
232
233 void clear_humongous_is_live_table();
234 void eagerly_reclaim_humongous_regions();
235
236 // The number of regions we could create by expansion.
237 uint _expansion_regions;
238
239 // The block offset table for the G1 heap.
240 G1BlockOffsetSharedArray* _bot_shared;
241
242 // Tears down the region sets / lists so that they are empty and the
243 // regions on the heap do not belong to a region set / list. The
244 // only exception is the humongous set which we leave unaltered. If
245 // free_list_only is true, it will only tear down the master free
246 // list. It is called before a Full GC (free_list_only == false) or
247 // before heap shrinking (free_list_only == true).
248 void tear_down_region_sets(bool free_list_only);
249
250 // Rebuilds the region sets / lists so that they are repopulated to
251 // reflect the contents of the heap. The only exception is the
252 // humongous set which was not torn down in the first place. If
253 // free_list_only is true, it will only rebuild the master free
254 // list. It is called after a Full GC (free_list_only == false) or
255 // after heap shrinking (free_list_only == true).
256 void rebuild_region_sets(bool free_list_only);
257
258 // Callback for region mapping changed events.
259 G1RegionMappingChangedListener _listener;
260
261 // The sequence of all heap regions in the heap.
262 HeapRegionManager _hrm;
263
264 // Class that handles the different kinds of allocations.
265 G1Allocator* _allocator;
266
267 // Statistics for each allocation context
268 AllocationContextStats _allocation_context_stats;
269
270 // PLAB sizing policy for survivors.
271 PLABStats _survivor_plab_stats;
272
273 // PLAB sizing policy for tenured objects.
274 PLABStats _old_plab_stats;
275
276 // It specifies whether we should attempt to expand the heap after a
277 // region allocation failure. If heap expansion fails we set this to
278 // false so that we don't re-attempt the heap expansion (it's likely
279 // that subsequent expansion attempts will also fail if one fails).
280 // Currently, it is only consulted during GC and it's reset at the
281 // start of each GC.
282 bool _expand_heap_after_alloc_failure;
283
284 // It resets the mutator alloc region before new allocations can take place.
285 void init_mutator_alloc_region();
286
287 // It releases the mutator alloc region.
288 void release_mutator_alloc_region();
289
290 // It initializes the GC alloc regions at the start of a GC.
291 void init_gc_alloc_regions(EvacuationInfo& evacuation_info);
292
293 // It releases the GC alloc regions at the end of a GC.
294 void release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info);
295
296 // It does any cleanup that needs to be done on the GC alloc regions
297 // before a Full GC.
298 void abandon_gc_alloc_regions();
299
300 // Helper for monitoring and management support.
301 G1MonitoringSupport* _g1mm;
302
303 // Records whether the region at the given index is kept live by roots or
304 // references from the young generation.
305 class HumongousIsLiveBiasedMappedArray : public G1BiasedMappedArray<bool> {
306 protected:
307 bool default_value() const { return false; }
308 public:
309 void clear() { G1BiasedMappedArray<bool>::clear(); }
310 void set_live(uint region) {
311 set_by_index(region, true);
312 }
313 bool is_live(uint region) {
314 return get_by_index(region);
315 }
316 };
317
318 HumongousIsLiveBiasedMappedArray _humongous_is_live;
319 // Stores whether during humongous object registration we found candidate regions.
320 // If not, we can skip a few steps.
321 bool _has_humongous_reclaim_candidates;
322
323 volatile unsigned _gc_time_stamp;
324
325 size_t* _surviving_young_words;
326
327 G1HRPrinter _hr_printer;
328
329 void setup_surviving_young_words();
330 void update_surviving_young_words(size_t* surv_young_words);
331 void cleanup_surviving_young_words();
332
333 // It decides whether an explicit GC should start a concurrent cycle
334 // instead of doing a STW GC. Currently, a concurrent cycle is
335 // explicitly started if:
336 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
337 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
338 // (c) cause == _g1_humongous_allocation
339 bool should_do_concurrent_full_gc(GCCause::Cause cause);
340
341 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
342 // concurrent cycles) we have started.
343 volatile unsigned int _old_marking_cycles_started;
344
345 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
346 // concurrent cycles) we have completed.
347 volatile unsigned int _old_marking_cycles_completed;
348
349 bool _concurrent_cycle_started;
350
351 // This is a non-product method that is helpful for testing. It is
352 // called at the end of a GC and artificially expands the heap by
353 // allocating a number of dead regions. This way we can induce very
354 // frequent marking cycles and stress the cleanup / concurrent
355 // cleanup code more (as all the regions that will be allocated by
356 // this method will be found dead by the marking cycle).
357 void allocate_dummy_regions() PRODUCT_RETURN;
358
359 // Clear RSets after a compaction. It also resets the GC time stamps.
360 void clear_rsets_post_compaction();
361
362 // If the HR printer is active, dump the state of the regions in the
363 // heap after a compaction.
364 void print_hrm_post_compaction();
365
366 double verify(bool guard, const char* msg);
367 void verify_before_gc();
368 void verify_after_gc();
369
370 void log_gc_header();
371 void log_gc_footer(double pause_time_sec);
372
373 // These are macros so that, if the assert fires, we get the correct
374 // line number, file, etc.
375
376 #define heap_locking_asserts_err_msg(_extra_message_) \
377 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
378 (_extra_message_), \
379 BOOL_TO_STR(Heap_lock->owned_by_self()), \
380 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
381 BOOL_TO_STR(Thread::current()->is_VM_thread()))
382
383 #define assert_heap_locked() \
384 do { \
385 assert(Heap_lock->owned_by_self(), \
386 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
387 } while (0)
388
389 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
390 do { \
391 assert(Heap_lock->owned_by_self() || \
392 (SafepointSynchronize::is_at_safepoint() && \
393 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
394 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
395 "should be at a safepoint")); \
396 } while (0)
397
398 #define assert_heap_locked_and_not_at_safepoint() \
399 do { \
400 assert(Heap_lock->owned_by_self() && \
401 !SafepointSynchronize::is_at_safepoint(), \
402 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
403 "should not be at a safepoint")); \
404 } while (0)
405
406 #define assert_heap_not_locked() \
407 do { \
408 assert(!Heap_lock->owned_by_self(), \
409 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
410 } while (0)
411
412 #define assert_heap_not_locked_and_not_at_safepoint() \
413 do { \
414 assert(!Heap_lock->owned_by_self() && \
415 !SafepointSynchronize::is_at_safepoint(), \
416 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
417 "should not be at a safepoint")); \
418 } while (0)
419
420 #define assert_at_safepoint(_should_be_vm_thread_) \
421 do { \
422 assert(SafepointSynchronize::is_at_safepoint() && \
423 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
424 heap_locking_asserts_err_msg("should be at a safepoint")); \
425 } while (0)
426
427 #define assert_not_at_safepoint() \
428 do { \
429 assert(!SafepointSynchronize::is_at_safepoint(), \
430 heap_locking_asserts_err_msg("should not be at a safepoint")); \
431 } while (0)
432
433 protected:
434
435 // The young region list.
436 YoungList* _young_list;
437
438 // The current policy object for the collector.
439 G1CollectorPolicy* _g1_policy;
440
441 // This is the second level of trying to allocate a new region. If
442 // new_region() didn't find a region on the free_list, this call will
443 // check whether there's anything available on the
444 // secondary_free_list and/or wait for more regions to appear on
445 // that list, if _free_regions_coming is set.
446 HeapRegion* new_region_try_secondary_free_list(bool is_old);
447
448 // Try to allocate a single non-humongous HeapRegion sufficient for
449 // an allocation of the given word_size. If do_expand is true,
450 // attempt to expand the heap if necessary to satisfy the allocation
451 // request. If the region is to be used as an old region or for a
452 // humongous object, set is_old to true. If not, to false.
453 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand);
454
455 // Initialize a contiguous set of free regions of length num_regions
456 // and starting at index first so that they appear as a single
457 // humongous region.
458 HeapWord* humongous_obj_allocate_initialize_regions(uint first,
459 uint num_regions,
460 size_t word_size,
461 AllocationContext_t context);
462
463 // Attempt to allocate a humongous object of the given size. Return
464 // NULL if unsuccessful.
465 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context);
466
467 // The following two methods, allocate_new_tlab() and
468 // mem_allocate(), are the two main entry points from the runtime
469 // into the G1's allocation routines. They have the following
470 // assumptions:
471 //
472 // * They should both be called outside safepoints.
473 //
474 // * They should both be called without holding the Heap_lock.
475 //
476 // * All allocation requests for new TLABs should go to
477 // allocate_new_tlab().
478 //
479 // * All non-TLAB allocation requests should go to mem_allocate().
480 //
481 // * If either call cannot satisfy the allocation request using the
482 // current allocating region, they will try to get a new one. If
483 // this fails, they will attempt to do an evacuation pause and
484 // retry the allocation.
485 //
486 // * If all allocation attempts fail, even after trying to schedule
487 // an evacuation pause, allocate_new_tlab() will return NULL,
488 // whereas mem_allocate() will attempt a heap expansion and/or
489 // schedule a Full GC.
490 //
491 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
492 // should never be called with word_size being humongous. All
493 // humongous allocation requests should go to mem_allocate() which
494 // will satisfy them with a special path.
495
496 virtual HeapWord* allocate_new_tlab(size_t word_size);
497
498 virtual HeapWord* mem_allocate(size_t word_size,
499 bool* gc_overhead_limit_was_exceeded);
500
501 // The following three methods take a gc_count_before_ret
502 // parameter which is used to return the GC count if the method
503 // returns NULL. Given that we are required to read the GC count
504 // while holding the Heap_lock, and these paths will take the
505 // Heap_lock at some point, it's easier to get them to read the GC
506 // count while holding the Heap_lock before they return NULL instead
507 // of the caller (namely: mem_allocate()) having to also take the
508 // Heap_lock just to read the GC count.
509
510 // First-level mutator allocation attempt: try to allocate out of
511 // the mutator alloc region without taking the Heap_lock. This
512 // should only be used for non-humongous allocations.
513 inline HeapWord* attempt_allocation(size_t word_size,
514 unsigned int* gc_count_before_ret,
515 int* gclocker_retry_count_ret);
516
517 // Second-level mutator allocation attempt: take the Heap_lock and
518 // retry the allocation attempt, potentially scheduling a GC
519 // pause. This should only be used for non-humongous allocations.
520 HeapWord* attempt_allocation_slow(size_t word_size,
521 AllocationContext_t context,
522 unsigned int* gc_count_before_ret,
523 int* gclocker_retry_count_ret);
524
525 // Takes the Heap_lock and attempts a humongous allocation. It can
526 // potentially schedule a GC pause.
527 HeapWord* attempt_allocation_humongous(size_t word_size,
528 unsigned int* gc_count_before_ret,
529 int* gclocker_retry_count_ret);
530
531 // Allocation attempt that should be called during safepoints (e.g.,
532 // at the end of a successful GC). expect_null_mutator_alloc_region
533 // specifies whether the mutator alloc region is expected to be NULL
534 // or not.
535 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
536 AllocationContext_t context,
537 bool expect_null_mutator_alloc_region);
538
539 // It dirties the cards that cover the block so that so that the post
540 // write barrier never queues anything when updating objects on this
541 // block. It is assumed (and in fact we assert) that the block
542 // belongs to a young region.
543 inline void dirty_young_block(HeapWord* start, size_t word_size);
544
545 // Allocate blocks during garbage collection. Will ensure an
546 // allocation region, either by picking one or expanding the
547 // heap, and then allocate a block of the given size. The block
548 // may not be a humongous - it must fit into a single heap region.
549 inline HeapWord* par_allocate_during_gc(InCSetState dest,
550 size_t word_size,
551 AllocationContext_t context);
552 // Ensure that no further allocations can happen in "r", bearing in mind
553 // that parallel threads might be attempting allocations.
554 void par_allocate_remaining_space(HeapRegion* r);
555
556 // Allocation attempt during GC for a survivor object / PLAB.
557 inline HeapWord* survivor_attempt_allocation(size_t word_size,
558 AllocationContext_t context);
559
560 // Allocation attempt during GC for an old object / PLAB.
561 inline HeapWord* old_attempt_allocation(size_t word_size,
562 AllocationContext_t context);
563
564 // These methods are the "callbacks" from the G1AllocRegion class.
565
566 // For mutator alloc regions.
567 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
568 void retire_mutator_alloc_region(HeapRegion* alloc_region,
569 size_t allocated_bytes);
570
571 // For GC alloc regions.
572 HeapRegion* new_gc_alloc_region(size_t word_size, uint count,
573 InCSetState dest);
574 void retire_gc_alloc_region(HeapRegion* alloc_region,
575 size_t allocated_bytes, InCSetState dest);
576
577 // - if explicit_gc is true, the GC is for a System.gc() or a heap
578 // inspection request and should collect the entire heap
579 // - if clear_all_soft_refs is true, all soft references should be
580 // cleared during the GC
581 // - if explicit_gc is false, word_size describes the allocation that
582 // the GC should attempt (at least) to satisfy
583 // - it returns false if it is unable to do the collection due to the
584 // GC locker being active, true otherwise
585 bool do_collection(bool explicit_gc,
586 bool clear_all_soft_refs,
587 size_t word_size);
588
589 // Callback from VM_G1CollectFull operation.
590 // Perform a full collection.
591 virtual void do_full_collection(bool clear_all_soft_refs);
592
593 // Resize the heap if necessary after a full collection. If this is
594 // after a collect-for allocation, "word_size" is the allocation size,
595 // and will be considered part of the used portion of the heap.
596 void resize_if_necessary_after_full_collection(size_t word_size);
597
598 // Callback from VM_G1CollectForAllocation operation.
599 // This function does everything necessary/possible to satisfy a
600 // failed allocation request (including collection, expansion, etc.)
601 HeapWord* satisfy_failed_allocation(size_t word_size,
602 AllocationContext_t context,
603 bool* succeeded);
604
605 // Attempting to expand the heap sufficiently
606 // to support an allocation of the given "word_size". If
607 // successful, perform the allocation and return the address of the
608 // allocated block, or else "NULL".
609 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context);
610
611 // Process any reference objects discovered during
612 // an incremental evacuation pause.
613 void process_discovered_references(uint no_of_gc_workers);
614
615 // Enqueue any remaining discovered references
616 // after processing.
617 void enqueue_discovered_references(uint no_of_gc_workers);
618
619 public:
620
621 G1Allocator* allocator() {
622 return _allocator;
623 }
624
625 G1MonitoringSupport* g1mm() {
626 assert(_g1mm != NULL, "should have been initialized");
627 return _g1mm;
628 }
629
630 // Expand the garbage-first heap by at least the given size (in bytes!).
631 // Returns true if the heap was expanded by the requested amount;
632 // false otherwise.
633 // (Rounds up to a HeapRegion boundary.)
634 bool expand(size_t expand_bytes);
635
636 // Returns the PLAB statistics for a given destination.
637 inline PLABStats* alloc_buffer_stats(InCSetState dest);
638
639 // Determines PLAB size for a given destination.
640 inline size_t desired_plab_sz(InCSetState dest);
641
642 inline AllocationContextStats& allocation_context_stats();
643
644 // Do anything common to GC's.
645 virtual void gc_prologue(bool full);
646 virtual void gc_epilogue(bool full);
647
648 inline void set_humongous_is_live(oop obj);
649
650 bool humongous_is_live(uint region) {
651 return _humongous_is_live.is_live(region);
652 }
653
654 // Returns whether the given region (which must be a humongous (start) region)
655 // is to be considered conservatively live regardless of any other conditions.
656 bool humongous_region_is_always_live(uint index);
657 // Register the given region to be part of the collection set.
658 inline void register_humongous_region_with_in_cset_fast_test(uint index);
659 // Register regions with humongous objects (actually on the start region) in
660 // the in_cset_fast_test table.
661 void register_humongous_regions_with_in_cset_fast_test();
662 // We register a region with the fast "in collection set" test. We
663 // simply set to true the array slot corresponding to this region.
664 void register_young_region_with_in_cset_fast_test(HeapRegion* r) {
665 _in_cset_fast_test.set_in_young(r->hrm_index());
666 }
667 void register_old_region_with_in_cset_fast_test(HeapRegion* r) {
668 _in_cset_fast_test.set_in_old(r->hrm_index());
669 }
670
671 // This is a fast test on whether a reference points into the
672 // collection set or not. Assume that the reference
673 // points into the heap.
674 inline bool in_cset_fast_test(oop obj);
675
676 void clear_cset_fast_test() {
677 _in_cset_fast_test.clear();
678 }
679
680 // This is called at the start of either a concurrent cycle or a Full
681 // GC to update the number of old marking cycles started.
682 void increment_old_marking_cycles_started();
683
684 // This is called at the end of either a concurrent cycle or a Full
685 // GC to update the number of old marking cycles completed. Those two
686 // can happen in a nested fashion, i.e., we start a concurrent
687 // cycle, a Full GC happens half-way through it which ends first,
688 // and then the cycle notices that a Full GC happened and ends
689 // too. The concurrent parameter is a boolean to help us do a bit
690 // tighter consistency checking in the method. If concurrent is
691 // false, the caller is the inner caller in the nesting (i.e., the
692 // Full GC). If concurrent is true, the caller is the outer caller
693 // in this nesting (i.e., the concurrent cycle). Further nesting is
694 // not currently supported. The end of this call also notifies
695 // the FullGCCount_lock in case a Java thread is waiting for a full
696 // GC to happen (e.g., it called System.gc() with
697 // +ExplicitGCInvokesConcurrent).
698 void increment_old_marking_cycles_completed(bool concurrent);
699
700 unsigned int old_marking_cycles_completed() {
701 return _old_marking_cycles_completed;
702 }
703
704 void register_concurrent_cycle_start(const Ticks& start_time);
705 void register_concurrent_cycle_end();
706 void trace_heap_after_concurrent_cycle();
707
708 G1YCType yc_type();
709
710 G1HRPrinter* hr_printer() { return &_hr_printer; }
711
712 // Frees a non-humongous region by initializing its contents and
713 // adding it to the free list that's passed as a parameter (this is
714 // usually a local list which will be appended to the master free
715 // list later). The used bytes of freed regions are accumulated in
716 // pre_used. If par is true, the region's RSet will not be freed
717 // up. The assumption is that this will be done later.
718 // The locked parameter indicates if the caller has already taken
719 // care of proper synchronization. This may allow some optimizations.
720 void free_region(HeapRegion* hr,
721 FreeRegionList* free_list,
722 bool par,
723 bool locked = false);
724
725 // Frees a humongous region by collapsing it into individual regions
726 // and calling free_region() for each of them. The freed regions
727 // will be added to the free list that's passed as a parameter (this
728 // is usually a local list which will be appended to the master free
729 // list later). The used bytes of freed regions are accumulated in
730 // pre_used. If par is true, the region's RSet will not be freed
731 // up. The assumption is that this will be done later.
732 void free_humongous_region(HeapRegion* hr,
733 FreeRegionList* free_list,
734 bool par);
735 protected:
736
737 // Shrink the garbage-first heap by at most the given size (in bytes!).
738 // (Rounds down to a HeapRegion boundary.)
739 virtual void shrink(size_t expand_bytes);
740 void shrink_helper(size_t expand_bytes);
741
742 #if TASKQUEUE_STATS
743 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
744 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
745 void reset_taskqueue_stats();
746 #endif // TASKQUEUE_STATS
747
748 // Schedule the VM operation that will do an evacuation pause to
749 // satisfy an allocation request of word_size. *succeeded will
750 // return whether the VM operation was successful (it did do an
751 // evacuation pause) or not (another thread beat us to it or the GC
752 // locker was active). Given that we should not be holding the
753 // Heap_lock when we enter this method, we will pass the
754 // gc_count_before (i.e., total_collections()) as a parameter since
755 // it has to be read while holding the Heap_lock. Currently, both
756 // methods that call do_collection_pause() release the Heap_lock
757 // before the call, so it's easy to read gc_count_before just before.
758 HeapWord* do_collection_pause(size_t word_size,
759 unsigned int gc_count_before,
760 bool* succeeded,
761 GCCause::Cause gc_cause);
762
763 // The guts of the incremental collection pause, executed by the vm
764 // thread. It returns false if it is unable to do the collection due
765 // to the GC locker being active, true otherwise
766 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
767
768 // Actually do the work of evacuating the collection set.
769 void evacuate_collection_set(EvacuationInfo& evacuation_info);
770
771 // The g1 remembered set of the heap.
772 G1RemSet* _g1_rem_set;
773
774 // A set of cards that cover the objects for which the Rsets should be updated
775 // concurrently after the collection.
776 DirtyCardQueueSet _dirty_card_queue_set;
777
778 // The closure used to refine a single card.
779 RefineCardTableEntryClosure* _refine_cte_cl;
780
781 // A function to check the consistency of dirty card logs.
782 void check_ct_logs_at_safepoint();
783
784 // A DirtyCardQueueSet that is used to hold cards that contain
785 // references into the current collection set. This is used to
786 // update the remembered sets of the regions in the collection
787 // set in the event of an evacuation failure.
788 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
789
790 // After a collection pause, make the regions in the CS into free
791 // regions.
792 void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info);
793
794 // Abandon the current collection set without recording policy
795 // statistics or updating free lists.
796 void abandon_collection_set(HeapRegion* cs_head);
797
798 // Applies "scan_non_heap_roots" to roots outside the heap,
799 // "scan_rs" to roots inside the heap (having done "set_region" to
800 // indicate the region in which the root resides),
801 // and does "scan_metadata" If "scan_rs" is
802 // NULL, then this step is skipped. The "worker_i"
803 // param is for use with parallel roots processing, and should be
804 // the "i" of the calling parallel worker thread's work(i) function.
805 // In the sequential case this param will be ignored.
806 void g1_process_roots(OopClosure* scan_non_heap_roots,
807 OopClosure* scan_non_heap_weak_roots,
808 OopsInHeapRegionClosure* scan_rs,
809 CLDClosure* scan_strong_clds,
810 CLDClosure* scan_weak_clds,
811 CodeBlobClosure* scan_strong_code,
812 uint worker_i);
813
814 // The concurrent marker (and the thread it runs in.)
815 ConcurrentMark* _cm;
816 ConcurrentMarkThread* _cmThread;
817 bool _mark_in_progress;
818
819 // The concurrent refiner.
820 ConcurrentG1Refine* _cg1r;
821
822 // The parallel task queues
823 RefToScanQueueSet *_task_queues;
824
825 // True iff a evacuation has failed in the current collection.
826 bool _evacuation_failed;
827
828 EvacuationFailedInfo* _evacuation_failed_info_array;
829
830 // Failed evacuations cause some logical from-space objects to have
831 // forwarding pointers to themselves. Reset them.
832 void remove_self_forwarding_pointers();
833
834 // Together, these store an object with a preserved mark, and its mark value.
835 Stack<oop, mtGC> _objs_with_preserved_marks;
836 Stack<markOop, mtGC> _preserved_marks_of_objs;
837
838 // Preserve the mark of "obj", if necessary, in preparation for its mark
839 // word being overwritten with a self-forwarding-pointer.
840 void preserve_mark_if_necessary(oop obj, markOop m);
841
842 // The stack of evac-failure objects left to be scanned.
843 GrowableArray<oop>* _evac_failure_scan_stack;
844 // The closure to apply to evac-failure objects.
845
846 OopsInHeapRegionClosure* _evac_failure_closure;
847 // Set the field above.
848 void
849 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
850 _evac_failure_closure = evac_failure_closure;
851 }
852
853 // Push "obj" on the scan stack.
854 void push_on_evac_failure_scan_stack(oop obj);
855 // Process scan stack entries until the stack is empty.
856 void drain_evac_failure_scan_stack();
857 // True iff an invocation of "drain_scan_stack" is in progress; to
858 // prevent unnecessary recursion.
859 bool _drain_in_progress;
860
861 // Do any necessary initialization for evacuation-failure handling.
862 // "cl" is the closure that will be used to process evac-failure
863 // objects.
864 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
865 // Do any necessary cleanup for evacuation-failure handling data
866 // structures.
867 void finalize_for_evac_failure();
868
869 // An attempt to evacuate "obj" has failed; take necessary steps.
870 oop handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, oop obj);
871 void handle_evacuation_failure_common(oop obj, markOop m);
872
873 #ifndef PRODUCT
874 // Support for forcing evacuation failures. Analogous to
875 // PromotionFailureALot for the other collectors.
876
877 // Records whether G1EvacuationFailureALot should be in effect
878 // for the current GC
879 bool _evacuation_failure_alot_for_current_gc;
880
881 // Used to record the GC number for interval checking when
882 // determining whether G1EvaucationFailureALot is in effect
883 // for the current GC.
884 size_t _evacuation_failure_alot_gc_number;
885
886 // Count of the number of evacuations between failures.
887 volatile size_t _evacuation_failure_alot_count;
888
889 // Set whether G1EvacuationFailureALot should be in effect
890 // for the current GC (based upon the type of GC and which
891 // command line flags are set);
892 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young,
893 bool during_initial_mark,
894 bool during_marking);
895
896 inline void set_evacuation_failure_alot_for_current_gc();
897
898 // Return true if it's time to cause an evacuation failure.
899 inline bool evacuation_should_fail();
900
901 // Reset the G1EvacuationFailureALot counters. Should be called at
902 // the end of an evacuation pause in which an evacuation failure occurred.
903 inline void reset_evacuation_should_fail();
904 #endif // !PRODUCT
905
906 // ("Weak") Reference processing support.
907 //
908 // G1 has 2 instances of the reference processor class. One
909 // (_ref_processor_cm) handles reference object discovery
910 // and subsequent processing during concurrent marking cycles.
911 //
912 // The other (_ref_processor_stw) handles reference object
913 // discovery and processing during full GCs and incremental
914 // evacuation pauses.
915 //
916 // During an incremental pause, reference discovery will be
917 // temporarily disabled for _ref_processor_cm and will be
918 // enabled for _ref_processor_stw. At the end of the evacuation
919 // pause references discovered by _ref_processor_stw will be
920 // processed and discovery will be disabled. The previous
921 // setting for reference object discovery for _ref_processor_cm
922 // will be re-instated.
923 //
924 // At the start of marking:
925 // * Discovery by the CM ref processor is verified to be inactive
926 // and it's discovered lists are empty.
927 // * Discovery by the CM ref processor is then enabled.
928 //
929 // At the end of marking:
930 // * Any references on the CM ref processor's discovered
931 // lists are processed (possibly MT).
932 //
933 // At the start of full GC we:
934 // * Disable discovery by the CM ref processor and
935 // empty CM ref processor's discovered lists
936 // (without processing any entries).
937 // * Verify that the STW ref processor is inactive and it's
938 // discovered lists are empty.
939 // * Temporarily set STW ref processor discovery as single threaded.
940 // * Temporarily clear the STW ref processor's _is_alive_non_header
941 // field.
942 // * Finally enable discovery by the STW ref processor.
943 //
944 // The STW ref processor is used to record any discovered
945 // references during the full GC.
946 //
947 // At the end of a full GC we:
948 // * Enqueue any reference objects discovered by the STW ref processor
949 // that have non-live referents. This has the side-effect of
950 // making the STW ref processor inactive by disabling discovery.
951 // * Verify that the CM ref processor is still inactive
952 // and no references have been placed on it's discovered
953 // lists (also checked as a precondition during initial marking).
954
955 // The (stw) reference processor...
956 ReferenceProcessor* _ref_processor_stw;
957
958 STWGCTimer* _gc_timer_stw;
959 ConcurrentGCTimer* _gc_timer_cm;
960
961 G1OldTracer* _gc_tracer_cm;
962 G1NewTracer* _gc_tracer_stw;
963
964 // During reference object discovery, the _is_alive_non_header
965 // closure (if non-null) is applied to the referent object to
966 // determine whether the referent is live. If so then the
967 // reference object does not need to be 'discovered' and can
968 // be treated as a regular oop. This has the benefit of reducing
969 // the number of 'discovered' reference objects that need to
970 // be processed.
971 //
972 // Instance of the is_alive closure for embedding into the
973 // STW reference processor as the _is_alive_non_header field.
974 // Supplying a value for the _is_alive_non_header field is
975 // optional but doing so prevents unnecessary additions to
976 // the discovered lists during reference discovery.
977 G1STWIsAliveClosure _is_alive_closure_stw;
978
979 // The (concurrent marking) reference processor...
980 ReferenceProcessor* _ref_processor_cm;
981
982 // Instance of the concurrent mark is_alive closure for embedding
983 // into the Concurrent Marking reference processor as the
984 // _is_alive_non_header field. Supplying a value for the
985 // _is_alive_non_header field is optional but doing so prevents
986 // unnecessary additions to the discovered lists during reference
987 // discovery.
988 G1CMIsAliveClosure _is_alive_closure_cm;
989
990 // Cache used by G1CollectedHeap::start_cset_region_for_worker().
991 HeapRegion** _worker_cset_start_region;
992
993 // Time stamp to validate the regions recorded in the cache
994 // used by G1CollectedHeap::start_cset_region_for_worker().
995 // The heap region entry for a given worker is valid iff
996 // the associated time stamp value matches the current value
997 // of G1CollectedHeap::_gc_time_stamp.
998 unsigned int* _worker_cset_start_region_time_stamp;
999
1000 enum G1H_process_roots_tasks {
1001 G1H_PS_filter_satb_buffers,
1002 G1H_PS_refProcessor_oops_do,
1003 // Leave this one last.
1004 G1H_PS_NumElements
1005 };
1006
1007 SubTasksDone* _process_strong_tasks;
1008
1009 volatile bool _free_regions_coming;
1010
1011 public:
1012
1013 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
1014
1015 void set_refine_cte_cl_concurrency(bool concurrent);
1016
1017 RefToScanQueue *task_queue(int i) const;
1018
1019 // A set of cards where updates happened during the GC
1020 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
1021
1022 // A DirtyCardQueueSet that is used to hold cards that contain
1023 // references into the current collection set. This is used to
1024 // update the remembered sets of the regions in the collection
1025 // set in the event of an evacuation failure.
1026 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
1027 { return _into_cset_dirty_card_queue_set; }
1028
1029 // Create a G1CollectedHeap with the specified policy.
1030 // Must call the initialize method afterwards.
1031 // May not return if something goes wrong.
1032 G1CollectedHeap(G1CollectorPolicy* policy);
1033
1034 // Initialize the G1CollectedHeap to have the initial and
1035 // maximum sizes and remembered and barrier sets
1036 // specified by the policy object.
1037 jint initialize();
1038
1039 virtual void stop();
1040
1041 // Return the (conservative) maximum heap alignment for any G1 heap
1042 static size_t conservative_max_heap_alignment();
1043
1044 // Initialize weak reference processing.
1045 virtual void ref_processing_init();
1046
1047 void set_par_threads(uint t) {
1048 SharedHeap::set_par_threads(t);
1049 // Done in SharedHeap but oddly there are
1050 // two _process_strong_tasks's in a G1CollectedHeap
1051 // so do it here too.
1052 _process_strong_tasks->set_n_threads(t);
1053 }
1054
1055 // Set _n_par_threads according to a policy TBD.
1056 void set_par_threads();
1057
1058 void set_n_termination(int t) {
1059 _process_strong_tasks->set_n_threads(t);
1060 }
1061
1062 virtual CollectedHeap::Name kind() const {
1063 return CollectedHeap::G1CollectedHeap;
1064 }
1065
1066 // The current policy object for the collector.
1067 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
1068
1069 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); }
1070
1071 // Adaptive size policy. No such thing for g1.
1072 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
1073
1074 // The rem set and barrier set.
1075 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
1076
1077 unsigned get_gc_time_stamp() {
1078 return _gc_time_stamp;
1079 }
1080
1081 inline void reset_gc_time_stamp();
1082
1083 void check_gc_time_stamps() PRODUCT_RETURN;
1084
1085 inline void increment_gc_time_stamp();
1086
1087 // Reset the given region's GC timestamp. If it's starts humongous,
1088 // also reset the GC timestamp of its corresponding
1089 // continues humongous regions too.
1090 void reset_gc_time_stamps(HeapRegion* hr);
1091
1092 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
1093 DirtyCardQueue* into_cset_dcq,
1094 bool concurrent, uint worker_i);
1095
1096 // The shared block offset table array.
1097 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
1098
1099 // Reference Processing accessors
1100
1101 // The STW reference processor....
1102 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1103
1104 // The Concurrent Marking reference processor...
1105 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1106
1107 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; }
1108 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; }
1109
1110 virtual size_t capacity() const;
1111 virtual size_t used() const;
1112 // This should be called when we're not holding the heap lock. The
1113 // result might be a bit inaccurate.
1114 size_t used_unlocked() const;
1115 size_t recalculate_used() const;
1116
1117 // These virtual functions do the actual allocation.
1118 // Some heaps may offer a contiguous region for shared non-blocking
1119 // allocation, via inlined code (by exporting the address of the top and
1120 // end fields defining the extent of the contiguous allocation region.)
1121 // But G1CollectedHeap doesn't yet support this.
1122
1123 virtual bool is_maximal_no_gc() const {
1124 return _hrm.available() == 0;
1125 }
1126
1127 // The current number of regions in the heap.
1128 uint num_regions() const { return _hrm.length(); }
1129
1130 // The max number of regions in the heap.
1131 uint max_regions() const { return _hrm.max_length(); }
1132
1133 // The number of regions that are completely free.
1134 uint num_free_regions() const { return _hrm.num_free_regions(); }
1135
1136 // The number of regions that are not completely free.
1137 uint num_used_regions() const { return num_regions() - num_free_regions(); }
1138
1139 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1140 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1141 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
1142 void verify_dirty_young_regions() PRODUCT_RETURN;
1143
1144 #ifndef PRODUCT
1145 // Make sure that the given bitmap has no marked objects in the
1146 // range [from,limit). If it does, print an error message and return
1147 // false. Otherwise, just return true. bitmap_name should be "prev"
1148 // or "next".
1149 bool verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
1150 HeapWord* from, HeapWord* limit);
1151
1152 // Verify that the prev / next bitmap range [tams,end) for the given
1153 // region has no marks. Return true if all is well, false if errors
1154 // are detected.
1155 bool verify_bitmaps(const char* caller, HeapRegion* hr);
1156 #endif // PRODUCT
1157
1158 // If G1VerifyBitmaps is set, verify that the marking bitmaps for
1159 // the given region do not have any spurious marks. If errors are
1160 // detected, print appropriate error messages and crash.
1161 void check_bitmaps(const char* caller, HeapRegion* hr) PRODUCT_RETURN;
1162
1163 // If G1VerifyBitmaps is set, verify that the marking bitmaps do not
1164 // have any spurious marks. If errors are detected, print
1165 // appropriate error messages and crash.
1166 void check_bitmaps(const char* caller) PRODUCT_RETURN;
1167
1168 // Do sanity check on the contents of the in-cset fast test table.
1169 bool check_cset_fast_test() PRODUCT_RETURN_( return true; );
1170
1171 // verify_region_sets() performs verification over the region
1172 // lists. It will be compiled in the product code to be used when
1173 // necessary (i.e., during heap verification).
1174 void verify_region_sets();
1175
1176 // verify_region_sets_optional() is planted in the code for
1177 // list verification in non-product builds (and it can be enabled in
1178 // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1).
1179 #if HEAP_REGION_SET_FORCE_VERIFY
1180 void verify_region_sets_optional() {
1181 verify_region_sets();
1182 }
1183 #else // HEAP_REGION_SET_FORCE_VERIFY
1184 void verify_region_sets_optional() { }
1185 #endif // HEAP_REGION_SET_FORCE_VERIFY
1186
1187 #ifdef ASSERT
1188 bool is_on_master_free_list(HeapRegion* hr) {
1189 return _hrm.is_free(hr);
1190 }
1191 #endif // ASSERT
1192
1193 // Wrapper for the region list operations that can be called from
1194 // methods outside this class.
1195
1196 void secondary_free_list_add(FreeRegionList* list) {
1197 _secondary_free_list.add_ordered(list);
1198 }
1199
1200 void append_secondary_free_list() {
1201 _hrm.insert_list_into_free_list(&_secondary_free_list);
1202 }
1203
1204 void append_secondary_free_list_if_not_empty_with_lock() {
1205 // If the secondary free list looks empty there's no reason to
1206 // take the lock and then try to append it.
1207 if (!_secondary_free_list.is_empty()) {
1208 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1209 append_secondary_free_list();
1210 }
1211 }
1212
1213 inline void old_set_remove(HeapRegion* hr);
1214
1215 size_t non_young_capacity_bytes() {
1216 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes();
1217 }
1218
1219 void set_free_regions_coming();
1220 void reset_free_regions_coming();
1221 bool free_regions_coming() { return _free_regions_coming; }
1222 void wait_while_free_regions_coming();
1223
1224 // Determine whether the given region is one that we are using as an
1225 // old GC alloc region.
1226 bool is_old_gc_alloc_region(HeapRegion* hr) {
1227 return _allocator->is_retained_old_region(hr);
1228 }
1229
1230 // Perform a collection of the heap; intended for use in implementing
1231 // "System.gc". This probably implies as full a collection as the
1232 // "CollectedHeap" supports.
1233 virtual void collect(GCCause::Cause cause);
1234
1235 // The same as above but assume that the caller holds the Heap_lock.
1236 void collect_locked(GCCause::Cause cause);
1237
1238 virtual bool copy_allocation_context_stats(const jint* contexts,
1239 jlong* totals,
1240 jbyte* accuracy,
1241 jint len);
1242
1243 // True iff an evacuation has failed in the most-recent collection.
1244 bool evacuation_failed() { return _evacuation_failed; }
1245
1246 void remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, const HeapRegionSetCount& humongous_regions_removed);
1247 void prepend_to_freelist(FreeRegionList* list);
1248 void decrement_summary_bytes(size_t bytes);
1249
1250 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1251 virtual bool is_in(const void* p) const;
1252 #ifdef ASSERT
1253 // Returns whether p is in one of the available areas of the heap. Slow but
1254 // extensive version.
1255 bool is_in_exact(const void* p) const;
1256 #endif
1257
1258 // Return "TRUE" iff the given object address is within the collection
1259 // set. Slow implementation.
1260 inline bool obj_in_cs(oop obj);
1261
1262 inline bool is_in_cset(oop obj);
1263
1264 inline bool is_in_cset_or_humongous(const oop obj);
1265
1266 private:
1267 // This array is used for a quick test on whether a reference points into
1268 // the collection set or not. Each of the array's elements denotes whether the
1269 // corresponding region is in the collection set or not.
1270 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test;
1271
1272 public:
1273
1274 inline InCSetState in_cset_state(const oop obj);
1275
1276 // Return "TRUE" iff the given object address is in the reserved
1277 // region of g1.
1278 bool is_in_g1_reserved(const void* p) const {
1279 return _hrm.reserved().contains(p);
1280 }
1281
1282 // Returns a MemRegion that corresponds to the space that has been
1283 // reserved for the heap
1284 MemRegion g1_reserved() const {
1285 return _hrm.reserved();
1286 }
1287
1288 virtual bool is_in_closed_subset(const void* p) const;
1289
1290 G1SATBCardTableLoggingModRefBS* g1_barrier_set() {
1291 return (G1SATBCardTableLoggingModRefBS*) barrier_set();
1292 }
1293
1294 // This resets the card table to all zeros. It is used after
1295 // a collection pause which used the card table to claim cards.
1296 void cleanUpCardTable();
1297
1298 // Iteration functions.
1299
1300 // Iterate over all the ref-containing fields of all objects, calling
1301 // "cl.do_oop" on each.
1302 virtual void oop_iterate(ExtendedOopClosure* cl);
1303
1304 // Iterate over all objects, calling "cl.do_object" on each.
1305 virtual void object_iterate(ObjectClosure* cl);
1306
1307 virtual void safe_object_iterate(ObjectClosure* cl) {
1308 object_iterate(cl);
1309 }
1310
1311 // Iterate over all spaces in use in the heap, in ascending address order.
1312 virtual void space_iterate(SpaceClosure* cl);
1313
1314 // Iterate over heap regions, in address order, terminating the
1315 // iteration early if the "doHeapRegion" method returns "true".
1316 void heap_region_iterate(HeapRegionClosure* blk) const;
1317
1318 // Return the region with the given index. It assumes the index is valid.
1319 inline HeapRegion* region_at(uint index) const;
1320
1321 // Calculate the region index of the given address. Given address must be
1322 // within the heap.
1323 inline uint addr_to_region(HeapWord* addr) const;
1324
1325 inline HeapWord* bottom_addr_for_region(uint index) const;
1326
1327 // Divide the heap region sequence into "chunks" of some size (the number
1328 // of regions divided by the number of parallel threads times some
1329 // overpartition factor, currently 4). Assumes that this will be called
1330 // in parallel by ParallelGCThreads worker threads with discinct worker
1331 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
1332 // calls will use the same "claim_value", and that that claim value is
1333 // different from the claim_value of any heap region before the start of
1334 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by
1335 // attempting to claim the first region in each chunk, and, if
1336 // successful, applying the closure to each region in the chunk (and
1337 // setting the claim value of the second and subsequent regions of the
1338 // chunk.) For now requires that "doHeapRegion" always returns "false",
1339 // i.e., that a closure never attempt to abort a traversal.
1340 void heap_region_par_iterate_chunked(HeapRegionClosure* cl,
1341 uint worker_id,
1342 uint num_workers,
1343 jint claim_value) const;
1344
1345 // It resets all the region claim values to the default.
1346 void reset_heap_region_claim_values();
1347
1348 // Resets the claim values of regions in the current
1349 // collection set to the default.
1350 void reset_cset_heap_region_claim_values();
1351
1352 #ifdef ASSERT
1353 bool check_heap_region_claim_values(jint claim_value);
1354
1355 // Same as the routine above but only checks regions in the
1356 // current collection set.
1357 bool check_cset_heap_region_claim_values(jint claim_value);
1358 #endif // ASSERT
1359
1360 // Clear the cached cset start regions and (more importantly)
1361 // the time stamps. Called when we reset the GC time stamp.
1362 void clear_cset_start_regions();
1363
1364 // Given the id of a worker, obtain or calculate a suitable
1365 // starting region for iterating over the current collection set.
1366 HeapRegion* start_cset_region_for_worker(uint worker_i);
1367
1368 // Iterate over the regions (if any) in the current collection set.
1369 void collection_set_iterate(HeapRegionClosure* blk);
1370
1371 // As above but starting from region r
1372 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1373
1374 HeapRegion* next_compaction_region(const HeapRegion* from) const;
1375
1376 // A CollectedHeap will contain some number of spaces. This finds the
1377 // space containing a given address, or else returns NULL.
1378 virtual Space* space_containing(const void* addr) const;
1379
1380 // Returns the HeapRegion that contains addr. addr must not be NULL.
1381 template <class T>
1382 inline HeapRegion* heap_region_containing_raw(const T addr) const;
1383
1384 // Returns the HeapRegion that contains addr. addr must not be NULL.
1385 // If addr is within a humongous continues region, it returns its humongous start region.
1386 template <class T>
1387 inline HeapRegion* heap_region_containing(const T addr) const;
1388
1389 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1390 // each address in the (reserved) heap is a member of exactly
1391 // one block. The defining characteristic of a block is that it is
1392 // possible to find its size, and thus to progress forward to the next
1393 // block. (Blocks may be of different sizes.) Thus, blocks may
1394 // represent Java objects, or they might be free blocks in a
1395 // free-list-based heap (or subheap), as long as the two kinds are
1396 // distinguishable and the size of each is determinable.
1397
1398 // Returns the address of the start of the "block" that contains the
1399 // address "addr". We say "blocks" instead of "object" since some heaps
1400 // may not pack objects densely; a chunk may either be an object or a
1401 // non-object.
1402 virtual HeapWord* block_start(const void* addr) const;
1403
1404 // Requires "addr" to be the start of a chunk, and returns its size.
1405 // "addr + size" is required to be the start of a new chunk, or the end
1406 // of the active area of the heap.
1407 virtual size_t block_size(const HeapWord* addr) const;
1408
1409 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1410 // the block is an object.
1411 virtual bool block_is_obj(const HeapWord* addr) const;
1412
1413 // Does this heap support heap inspection? (+PrintClassHistogram)
1414 virtual bool supports_heap_inspection() const { return true; }
1415
1416 // Section on thread-local allocation buffers (TLABs)
1417 // See CollectedHeap for semantics.
1418
1419 bool supports_tlab_allocation() const;
1420 size_t tlab_capacity(Thread* ignored) const;
1421 size_t tlab_used(Thread* ignored) const;
1422 size_t max_tlab_size() const;
1423 size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1424
1425 // Can a compiler initialize a new object without store barriers?
1426 // This permission only extends from the creation of a new object
1427 // via a TLAB up to the first subsequent safepoint. If such permission
1428 // is granted for this heap type, the compiler promises to call
1429 // defer_store_barrier() below on any slow path allocation of
1430 // a new object for which such initializing store barriers will
1431 // have been elided. G1, like CMS, allows this, but should be
1432 // ready to provide a compensating write barrier as necessary
1433 // if that storage came out of a non-young region. The efficiency
1434 // of this implementation depends crucially on being able to
1435 // answer very efficiently in constant time whether a piece of
1436 // storage in the heap comes from a young region or not.
1437 // See ReduceInitialCardMarks.
1438 virtual bool can_elide_tlab_store_barriers() const {
1439 return true;
1440 }
1441
1442 virtual bool card_mark_must_follow_store() const {
1443 return true;
1444 }
1445
1446 inline bool is_in_young(const oop obj);
1447
1448 #ifdef ASSERT
1449 virtual bool is_in_partial_collection(const void* p);
1450 #endif
1451
1452 virtual bool is_scavengable(const void* addr);
1453
1454 // We don't need barriers for initializing stores to objects
1455 // in the young gen: for the SATB pre-barrier, there is no
1456 // pre-value that needs to be remembered; for the remembered-set
1457 // update logging post-barrier, we don't maintain remembered set
1458 // information for young gen objects.
1459 virtual inline bool can_elide_initializing_store_barrier(oop new_obj);
1460
1461 // Returns "true" iff the given word_size is "very large".
1462 static bool isHumongous(size_t word_size) {
1463 // Note this has to be strictly greater-than as the TLABs
1464 // are capped at the humongous thresold and we want to
1465 // ensure that we don't try to allocate a TLAB as
1466 // humongous and that we don't allocate a humongous
1467 // object in a TLAB.
1468 return word_size > _humongous_object_threshold_in_words;
1469 }
1470
1471 // Update mod union table with the set of dirty cards.
1472 void updateModUnion();
1473
1474 // Set the mod union bits corresponding to the given memRegion. Note
1475 // that this is always a safe operation, since it doesn't clear any
1476 // bits.
1477 void markModUnionRange(MemRegion mr);
1478
1479 // Records the fact that a marking phase is no longer in progress.
1480 void set_marking_complete() {
1481 _mark_in_progress = false;
1482 }
1483 void set_marking_started() {
1484 _mark_in_progress = true;
1485 }
1486 bool mark_in_progress() {
1487 return _mark_in_progress;
1488 }
1489
1490 // Print the maximum heap capacity.
1491 virtual size_t max_capacity() const;
1492
1493 virtual jlong millis_since_last_gc();
1494
1495
1496 // Convenience function to be used in situations where the heap type can be
1497 // asserted to be this type.
1498 static G1CollectedHeap* heap();
1499
1500 void set_region_short_lived_locked(HeapRegion* hr);
1501 // add appropriate methods for any other surv rate groups
1502
1503 YoungList* young_list() const { return _young_list; }
1504
1505 // debugging
1506 bool check_young_list_well_formed() {
1507 return _young_list->check_list_well_formed();
1508 }
1509
1510 bool check_young_list_empty(bool check_heap,
1511 bool check_sample = true);
1512
1513 // *** Stuff related to concurrent marking. It's not clear to me that so
1514 // many of these need to be public.
1515
1516 // The functions below are helper functions that a subclass of
1517 // "CollectedHeap" can use in the implementation of its virtual
1518 // functions.
1519 // This performs a concurrent marking of the live objects in a
1520 // bitmap off to the side.
1521 void doConcurrentMark();
1522
1523 bool isMarkedPrev(oop obj) const;
1524 bool isMarkedNext(oop obj) const;
1525
1526 // Determine if an object is dead, given the object and also
1527 // the region to which the object belongs. An object is dead
1528 // iff a) it was not allocated since the last mark and b) it
1529 // is not marked.
1530 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1531 return
1532 !hr->obj_allocated_since_prev_marking(obj) &&
1533 !isMarkedPrev(obj);
1534 }
1535
1536 // This function returns true when an object has been
1537 // around since the previous marking and hasn't yet
1538 // been marked during this marking.
1539 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1540 return
1541 !hr->obj_allocated_since_next_marking(obj) &&
1542 !isMarkedNext(obj);
1543 }
1544
1545 // Determine if an object is dead, given only the object itself.
1546 // This will find the region to which the object belongs and
1547 // then call the region version of the same function.
1548
1549 // Added if it is NULL it isn't dead.
1550
1551 inline bool is_obj_dead(const oop obj) const;
1552
1553 inline bool is_obj_ill(const oop obj) const;
1554
1555 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo);
1556 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo);
1557 bool is_marked(oop obj, VerifyOption vo);
1558 const char* top_at_mark_start_str(VerifyOption vo);
1559
1560 ConcurrentMark* concurrent_mark() const { return _cm; }
1561
1562 // Refinement
1563
1564 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1565
1566 // The dirty cards region list is used to record a subset of regions
1567 // whose cards need clearing. The list if populated during the
1568 // remembered set scanning and drained during the card table
1569 // cleanup. Although the methods are reentrant, population/draining
1570 // phases must not overlap. For synchronization purposes the last
1571 // element on the list points to itself.
1572 HeapRegion* _dirty_cards_region_list;
1573 void push_dirty_cards_region(HeapRegion* hr);
1574 HeapRegion* pop_dirty_cards_region();
1575
1576 // Optimized nmethod scanning support routines
1577
1578 // Register the given nmethod with the G1 heap
1579 virtual void register_nmethod(nmethod* nm);
1580
1581 // Unregister the given nmethod from the G1 heap
1582 virtual void unregister_nmethod(nmethod* nm);
1583
1584 // Free up superfluous code root memory.
1585 void purge_code_root_memory();
1586
1587 // Rebuild the stong code root lists for each region
1588 // after a full GC
1589 void rebuild_strong_code_roots();
1590
1591 // Delete entries for dead interned string and clean up unreferenced symbols
1592 // in symbol table, possibly in parallel.
1593 void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true);
1594
1595 // Parallel phase of unloading/cleaning after G1 concurrent mark.
1596 void parallel_cleaning(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool class_unloading_occurred);
1597
1598 // Redirty logged cards in the refinement queue.
1599 void redirty_logged_cards();
1600 // Verification
1601
1602 // The following is just to alert the verification code
1603 // that a full collection has occurred and that the
1604 // remembered sets are no longer up to date.
1605 bool _full_collection;
1606 void set_full_collection() { _full_collection = true;}
1607 void clear_full_collection() {_full_collection = false;}
1608 bool full_collection() {return _full_collection;}
1609
1610 // Perform any cleanup actions necessary before allowing a verification.
1611 virtual void prepare_for_verify();
1612
1613 // Perform verification.
1614
1615 // vo == UsePrevMarking -> use "prev" marking information,
1616 // vo == UseNextMarking -> use "next" marking information
1617 // vo == UseMarkWord -> use the mark word in the object header
1618 //
1619 // NOTE: Only the "prev" marking information is guaranteed to be
1620 // consistent most of the time, so most calls to this should use
1621 // vo == UsePrevMarking.
1622 // Currently, there is only one case where this is called with
1623 // vo == UseNextMarking, which is to verify the "next" marking
1624 // information at the end of remark.
1625 // Currently there is only one place where this is called with
1626 // vo == UseMarkWord, which is to verify the marking during a
1627 // full GC.
1628 void verify(bool silent, VerifyOption vo);
1629
1630 // Override; it uses the "prev" marking information
1631 virtual void verify(bool silent);
1632
1633 // The methods below are here for convenience and dispatch the
1634 // appropriate method depending on value of the given VerifyOption
1635 // parameter. The values for that parameter, and their meanings,
1636 // are the same as those above.
1637
1638 bool is_obj_dead_cond(const oop obj,
1639 const HeapRegion* hr,
1640 const VerifyOption vo) const;
1641
1642 bool is_obj_dead_cond(const oop obj,
1643 const VerifyOption vo) const;
1644
1645 // Printing
1646
1647 virtual void print_on(outputStream* st) const;
1648 virtual void print_extended_on(outputStream* st) const;
1649 virtual void print_on_error(outputStream* st) const;
1650
1651 virtual void print_gc_threads_on(outputStream* st) const;
1652 virtual void gc_threads_do(ThreadClosure* tc) const;
1653
1654 // Override
1655 void print_tracing_info() const;
1656
1657 // The following two methods are helpful for debugging RSet issues.
1658 void print_cset_rsets() PRODUCT_RETURN;
1659 void print_all_rsets() PRODUCT_RETURN;
1660
1661 public:
1662 size_t pending_card_num();
1663 size_t cards_scanned();
1664
1665 protected:
1666 size_t _max_heap_capacity;
1667 };
1668
1669 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP