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
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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_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/g1AllocationContext.hpp"
31 #include "gc/g1/g1Allocator.hpp"
32 #include "gc/g1/g1BiasedArray.hpp"
33 #include "gc/g1/g1CollectorState.hpp"
34 #include "gc/g1/g1HRPrinter.hpp"
35 #include "gc/g1/g1InCSetState.hpp"
36 #include "gc/g1/g1MonitoringSupport.hpp"
37 #include "gc/g1/g1SATBCardTableModRefBS.hpp"
38 #include "gc/g1/g1YCTypes.hpp"
39 #include "gc/g1/hSpaceCounters.hpp"
40 #include "gc/g1/heapRegionManager.hpp"
41 #include "gc/g1/heapRegionSet.hpp"
42 #include "gc/shared/barrierSet.hpp"
43 #include "gc/shared/collectedHeap.hpp"
44 #include "memory/memRegion.hpp"
45 #include "utilities/stack.hpp"
46
47 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
48 // It uses the "Garbage First" heap organization and algorithm, which
49 // may combine concurrent marking with parallel, incremental compaction of
50 // heap subsets that will yield large amounts of garbage.
51
52 // Forward declarations
53 class HeapRegion;
54 class HRRSCleanupTask;
55 class GenerationSpec;
56 class OopsInHeapRegionClosure;
57 class G1KlassScanClosure;
58 class G1ParScanThreadState;
59 class ObjectClosure;
60 class SpaceClosure;
61 class CompactibleSpaceClosure;
62 class Space;
63 class G1CollectorPolicy;
64 class GenRemSet;
65 class G1RemSet;
66 class HeapRegionRemSetIterator;
67 class ConcurrentMark;
68 class ConcurrentMarkThread;
69 class ConcurrentG1Refine;
70 class ConcurrentGCTimer;
71 class GenerationCounters;
72 class STWGCTimer;
73 class G1NewTracer;
74 class G1OldTracer;
75 class EvacuationFailedInfo;
76 class nmethod;
77 class Ticks;
78 class FlexibleWorkGang;
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 eden_length() { return length() - survivor_length(); }
115 uint survivor_length() { return _survivor_length; }
116
117 // Currently we do not keep track of the used byte sum for the
118 // young list and the survivors and it'd be quite a lot of work to
119 // do so. When we'll eventually replace the young list with
120 // instances of HeapRegionLinkedList we'll get that for free. So,
121 // we'll report the more accurate information then.
122 size_t eden_used_bytes() {
123 assert(length() >= survivor_length(), "invariant");
124 return (size_t) eden_length() * HeapRegion::GrainBytes;
125 }
126 size_t survivor_used_bytes() {
127 return (size_t) survivor_length() * HeapRegion::GrainBytes;
128 }
129
130 void rs_length_sampling_init();
131 bool rs_length_sampling_more();
132 void rs_length_sampling_next();
133
134 void reset_sampled_info() {
135 _last_sampled_rs_lengths = 0;
136 }
137 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }
138
139 // for development purposes
140 void reset_auxilary_lists();
141 void clear() { _head = NULL; _length = 0; }
142
143 void clear_survivors() {
144 _survivor_head = NULL;
145 _survivor_tail = NULL;
146 _survivor_length = 0;
147 }
148
149 HeapRegion* first_region() { return _head; }
150 HeapRegion* first_survivor_region() { return _survivor_head; }
151 HeapRegion* last_survivor_region() { return _survivor_tail; }
152
153 // debugging
154 bool check_list_well_formed();
155 bool check_list_empty(bool check_sample = true);
156 void print();
157 };
158
159 // The G1 STW is alive closure.
160 // An instance is embedded into the G1CH and used as the
161 // (optional) _is_alive_non_header closure in the STW
162 // reference processor. It is also extensively used during
163 // reference processing during STW evacuation pauses.
164 class G1STWIsAliveClosure: public BoolObjectClosure {
165 G1CollectedHeap* _g1;
166 public:
167 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
168 bool do_object_b(oop p);
169 };
170
171 class RefineCardTableEntryClosure;
172
173 class G1RegionMappingChangedListener : public G1MappingChangedListener {
174 private:
175 void reset_from_card_cache(uint start_idx, size_t num_regions);
176 public:
177 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
178 };
179
180 class G1CollectedHeap : public CollectedHeap {
181 friend class VM_CollectForMetadataAllocation;
182 friend class VM_G1CollectForAllocation;
183 friend class VM_G1CollectFull;
184 friend class VM_G1IncCollectionPause;
185 friend class VMStructs;
186 friend class MutatorAllocRegion;
187 friend class SurvivorGCAllocRegion;
188 friend class OldGCAllocRegion;
189 friend class G1Allocator;
190 friend class G1ArchiveAllocator;
191
192 // Closures used in implementation.
193 friend class G1ParScanThreadState;
194 friend class G1ParTask;
195 friend class G1PLABAllocator;
196 friend class G1PrepareCompactClosure;
197
198 // Other related classes.
199 friend class HeapRegionClaimer;
200
201 // Testing classes.
202 friend class G1CheckCSetFastTableClosure;
203
204 private:
205 FlexibleWorkGang* _workers;
206
207 static size_t _humongous_object_threshold_in_words;
208
209 // The secondary free list which contains regions that have been
210 // freed up during the cleanup process. This will be appended to
211 // the master free list when appropriate.
212 FreeRegionList _secondary_free_list;
213
214 // It keeps track of the old regions.
215 HeapRegionSet _old_set;
216
217 // It keeps track of the humongous regions.
218 HeapRegionSet _humongous_set;
219
220 void eagerly_reclaim_humongous_regions();
221
222 // The number of regions we could create by expansion.
223 uint _expansion_regions;
224
225 // The block offset table for the G1 heap.
226 G1BlockOffsetSharedArray* _bot_shared;
227
228 // Tears down the region sets / lists so that they are empty and the
229 // regions on the heap do not belong to a region set / list. The
230 // only exception is the humongous set which we leave unaltered. If
231 // free_list_only is true, it will only tear down the master free
232 // list. It is called before a Full GC (free_list_only == false) or
233 // before heap shrinking (free_list_only == true).
234 void tear_down_region_sets(bool free_list_only);
235
236 // Rebuilds the region sets / lists so that they are repopulated to
237 // reflect the contents of the heap. The only exception is the
238 // humongous set which was not torn down in the first place. If
239 // free_list_only is true, it will only rebuild the master free
240 // list. It is called after a Full GC (free_list_only == false) or
241 // after heap shrinking (free_list_only == true).
242 void rebuild_region_sets(bool free_list_only);
243
244 // Callback for region mapping changed events.
245 G1RegionMappingChangedListener _listener;
246
247 // The sequence of all heap regions in the heap.
248 HeapRegionManager _hrm;
249
250 // Handles non-humongous allocations in the G1CollectedHeap.
251 G1Allocator* _allocator;
252
253 // Outside of GC pauses, the number of bytes used in all regions other
254 // than the current allocation region(s).
255 size_t _summary_bytes_used;
256
257 void increase_used(size_t bytes);
258 void decrease_used(size_t bytes);
259
260 void set_used(size_t bytes);
261
262 // Class that handles archive allocation ranges.
263 G1ArchiveAllocator* _archive_allocator;
264
265 // Statistics for each allocation context
266 AllocationContextStats _allocation_context_stats;
267
268 // PLAB sizing policy for survivors.
269 PLABStats _survivor_plab_stats;
270
271 // PLAB sizing policy for tenured objects.
272 PLABStats _old_plab_stats;
273
274 // It specifies whether we should attempt to expand the heap after a
275 // region allocation failure. If heap expansion fails we set this to
276 // false so that we don't re-attempt the heap expansion (it's likely
277 // that subsequent expansion attempts will also fail if one fails).
278 // Currently, it is only consulted during GC and it's reset at the
279 // start of each GC.
280 bool _expand_heap_after_alloc_failure;
281
282 // Helper for monitoring and management support.
283 G1MonitoringSupport* _g1mm;
284
285 // Records whether the region at the given index is (still) a
286 // candidate for eager reclaim. Only valid for humongous start
287 // regions; other regions have unspecified values. Humongous start
288 // regions are initialized at start of collection pause, with
289 // candidates removed from the set as they are found reachable from
290 // roots or the young generation.
291 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> {
292 protected:
293 bool default_value() const { return false; }
294 public:
295 void clear() { G1BiasedMappedArray<bool>::clear(); }
296 void set_candidate(uint region, bool value) {
297 set_by_index(region, value);
298 }
299 bool is_candidate(uint region) {
300 return get_by_index(region);
301 }
302 };
303
304 HumongousReclaimCandidates _humongous_reclaim_candidates;
305 // Stores whether during humongous object registration we found candidate regions.
306 // If not, we can skip a few steps.
307 bool _has_humongous_reclaim_candidates;
308
309 volatile unsigned _gc_time_stamp;
310
311 size_t* _surviving_young_words;
312
313 G1HRPrinter _hr_printer;
314
315 void setup_surviving_young_words();
316 void update_surviving_young_words(size_t* surv_young_words);
317 void cleanup_surviving_young_words();
318
319 // It decides whether an explicit GC should start a concurrent cycle
320 // instead of doing a STW GC. Currently, a concurrent cycle is
321 // explicitly started if:
322 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
323 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
324 // (c) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent.
325 // (d) cause == _g1_humongous_allocation
326 bool should_do_concurrent_full_gc(GCCause::Cause cause);
327
328 // indicates whether we are in young or mixed GC mode
329 G1CollectorState _collector_state;
330
331 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
332 // concurrent cycles) we have started.
333 volatile uint _old_marking_cycles_started;
334
335 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
336 // concurrent cycles) we have completed.
337 volatile uint _old_marking_cycles_completed;
338
339 bool _heap_summary_sent;
340
341 // This is a non-product method that is helpful for testing. It is
342 // called at the end of a GC and artificially expands the heap by
343 // allocating a number of dead regions. This way we can induce very
344 // frequent marking cycles and stress the cleanup / concurrent
345 // cleanup code more (as all the regions that will be allocated by
346 // this method will be found dead by the marking cycle).
347 void allocate_dummy_regions() PRODUCT_RETURN;
348
349 // Clear RSets after a compaction. It also resets the GC time stamps.
350 void clear_rsets_post_compaction();
351
352 // If the HR printer is active, dump the state of the regions in the
353 // heap after a compaction.
354 void print_hrm_post_compaction();
355
356 // Create a memory mapper for auxiliary data structures of the given size and
357 // translation factor.
358 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description,
359 size_t size,
360 size_t translation_factor);
361
362 double verify(bool guard, const char* msg);
363 void verify_before_gc();
364 void verify_after_gc();
365
366 void log_gc_header();
367 void log_gc_footer(double pause_time_sec);
368
369 void trace_heap(GCWhen::Type when, const GCTracer* tracer);
370
371 // These are macros so that, if the assert fires, we get the correct
372 // line number, file, etc.
373
374 #define heap_locking_asserts_err_msg(_extra_message_) \
375 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
376 (_extra_message_), \
377 BOOL_TO_STR(Heap_lock->owned_by_self()), \
378 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
379 BOOL_TO_STR(Thread::current()->is_VM_thread()))
380
381 #define assert_heap_locked() \
382 do { \
383 assert(Heap_lock->owned_by_self(), \
384 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
385 } while (0)
386
387 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
388 do { \
389 assert(Heap_lock->owned_by_self() || \
390 (SafepointSynchronize::is_at_safepoint() && \
391 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
392 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
393 "should be at a safepoint")); \
394 } while (0)
395
396 #define assert_heap_locked_and_not_at_safepoint() \
397 do { \
398 assert(Heap_lock->owned_by_self() && \
399 !SafepointSynchronize::is_at_safepoint(), \
400 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
401 "should not be at a safepoint")); \
402 } while (0)
403
404 #define assert_heap_not_locked() \
405 do { \
406 assert(!Heap_lock->owned_by_self(), \
407 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
408 } while (0)
409
410 #define assert_heap_not_locked_and_not_at_safepoint() \
411 do { \
412 assert(!Heap_lock->owned_by_self() && \
413 !SafepointSynchronize::is_at_safepoint(), \
414 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
415 "should not be at a safepoint")); \
416 } while (0)
417
418 #define assert_at_safepoint(_should_be_vm_thread_) \
419 do { \
420 assert(SafepointSynchronize::is_at_safepoint() && \
421 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
422 heap_locking_asserts_err_msg("should be at a safepoint")); \
423 } while (0)
424
425 #define assert_not_at_safepoint() \
426 do { \
427 assert(!SafepointSynchronize::is_at_safepoint(), \
428 heap_locking_asserts_err_msg("should not be at a safepoint")); \
429 } while (0)
430
431 protected:
432
433 // The young region list.
434 YoungList* _young_list;
435
436 // The current policy object for the collector.
437 G1CollectorPolicy* _g1_policy;
438
439 // This is the second level of trying to allocate a new region. If
440 // new_region() didn't find a region on the free_list, this call will
441 // check whether there's anything available on the
442 // secondary_free_list and/or wait for more regions to appear on
443 // that list, if _free_regions_coming is set.
444 HeapRegion* new_region_try_secondary_free_list(bool is_old);
445
446 // Try to allocate a single non-humongous HeapRegion sufficient for
447 // an allocation of the given word_size. If do_expand is true,
448 // attempt to expand the heap if necessary to satisfy the allocation
449 // request. If the region is to be used as an old region or for a
450 // humongous object, set is_old to true. If not, to false.
451 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand);
452
453 // Initialize a contiguous set of free regions of length num_regions
454 // and starting at index first so that they appear as a single
455 // humongous region.
456 HeapWord* humongous_obj_allocate_initialize_regions(uint first,
457 uint num_regions,
458 size_t word_size,
459 AllocationContext_t context);
460
461 // Attempt to allocate a humongous object of the given size. Return
462 // NULL if unsuccessful.
463 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context);
464
465 // The following two methods, allocate_new_tlab() and
466 // mem_allocate(), are the two main entry points from the runtime
467 // into the G1's allocation routines. They have the following
468 // assumptions:
469 //
470 // * They should both be called outside safepoints.
471 //
472 // * They should both be called without holding the Heap_lock.
473 //
474 // * All allocation requests for new TLABs should go to
475 // allocate_new_tlab().
476 //
477 // * All non-TLAB allocation requests should go to mem_allocate().
478 //
479 // * If either call cannot satisfy the allocation request using the
480 // current allocating region, they will try to get a new one. If
481 // this fails, they will attempt to do an evacuation pause and
482 // retry the allocation.
483 //
484 // * If all allocation attempts fail, even after trying to schedule
485 // an evacuation pause, allocate_new_tlab() will return NULL,
486 // whereas mem_allocate() will attempt a heap expansion and/or
487 // schedule a Full GC.
488 //
489 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
490 // should never be called with word_size being humongous. All
491 // humongous allocation requests should go to mem_allocate() which
492 // will satisfy them with a special path.
493
494 virtual HeapWord* allocate_new_tlab(size_t word_size);
495
496 virtual HeapWord* mem_allocate(size_t word_size,
497 bool* gc_overhead_limit_was_exceeded);
498
499 // The following three methods take a gc_count_before_ret
500 // parameter which is used to return the GC count if the method
501 // returns NULL. Given that we are required to read the GC count
502 // while holding the Heap_lock, and these paths will take the
503 // Heap_lock at some point, it's easier to get them to read the GC
504 // count while holding the Heap_lock before they return NULL instead
505 // of the caller (namely: mem_allocate()) having to also take the
506 // Heap_lock just to read the GC count.
507
508 // First-level mutator allocation attempt: try to allocate out of
509 // the mutator alloc region without taking the Heap_lock. This
510 // should only be used for non-humongous allocations.
511 inline HeapWord* attempt_allocation(size_t word_size,
512 uint* gc_count_before_ret,
513 uint* gclocker_retry_count_ret);
514
515 // Second-level mutator allocation attempt: take the Heap_lock and
516 // retry the allocation attempt, potentially scheduling a GC
517 // pause. This should only be used for non-humongous allocations.
518 HeapWord* attempt_allocation_slow(size_t word_size,
519 AllocationContext_t context,
520 uint* gc_count_before_ret,
521 uint* gclocker_retry_count_ret);
522
523 // Takes the Heap_lock and attempts a humongous allocation. It can
524 // potentially schedule a GC pause.
525 HeapWord* attempt_allocation_humongous(size_t word_size,
526 uint* gc_count_before_ret,
527 uint* gclocker_retry_count_ret);
528
529 // Allocation attempt that should be called during safepoints (e.g.,
530 // at the end of a successful GC). expect_null_mutator_alloc_region
531 // specifies whether the mutator alloc region is expected to be NULL
532 // or not.
533 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
534 AllocationContext_t context,
535 bool expect_null_mutator_alloc_region);
536
537 // It dirties the cards that cover the block so that so that the post
538 // write barrier never queues anything when updating objects on this
539 // block. It is assumed (and in fact we assert) that the block
540 // belongs to a young region.
541 inline void dirty_young_block(HeapWord* start, size_t word_size);
542
543 // Do we have more free regions to allocate into?
544 inline bool has_more_free_regions() const;
545
546 // These methods are the "callbacks" from the G1AllocRegion class.
547
548 // For mutator alloc regions.
549 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
550 void retire_mutator_alloc_region(HeapRegion* alloc_region,
551 size_t allocated_bytes);
552
553 // For GC alloc regions.
554 HeapRegion* new_gc_alloc_region(size_t word_size, uint count,
555 InCSetState dest);
556 void retire_gc_alloc_region(HeapRegion* alloc_region,
557 size_t allocated_bytes, InCSetState dest);
558
559 // Allocate the highest free region in the reserved heap. This will commit
560 // regions as necessary.
561 HeapRegion* alloc_highest_free_region();
562
563 // - if explicit_gc is true, the GC is for a System.gc() or a heap
564 // inspection request and should collect the entire heap
565 // - if clear_all_soft_refs is true, all soft references should be
566 // cleared during the GC
567 // - if explicit_gc is false, word_size describes the allocation that
568 // the GC should attempt (at least) to satisfy
569 // - it returns false if it is unable to do the collection due to the
570 // GC locker being active, true otherwise
571 bool do_collection(bool explicit_gc,
572 bool clear_all_soft_refs,
573 size_t word_size);
574
575 // Callback from VM_G1CollectFull operation.
576 // Perform a full collection.
577 virtual void do_full_collection(bool clear_all_soft_refs);
578
579 // Resize the heap if necessary after a full collection. If this is
580 // after a collect-for allocation, "word_size" is the allocation size,
581 // and will be considered part of the used portion of the heap.
582 void resize_if_necessary_after_full_collection(size_t word_size);
583
584 // Callback from VM_G1CollectForAllocation operation.
585 // This function does everything necessary/possible to satisfy a
586 // failed allocation request (including collection, expansion, etc.)
587 HeapWord* satisfy_failed_allocation(size_t word_size,
588 AllocationContext_t context,
589 bool* succeeded);
590
591 // Attempting to expand the heap sufficiently
592 // to support an allocation of the given "word_size". If
593 // successful, perform the allocation and return the address of the
594 // allocated block, or else "NULL".
595 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context);
596
597 // Process any reference objects discovered during
598 // an incremental evacuation pause.
599 void process_discovered_references();
600
601 // Enqueue any remaining discovered references
602 // after processing.
603 void enqueue_discovered_references();
604
605 public:
606 FlexibleWorkGang* workers() const { return _workers; }
607
608 G1Allocator* allocator() {
609 return _allocator;
610 }
611
612 G1MonitoringSupport* g1mm() {
613 assert(_g1mm != NULL, "should have been initialized");
614 return _g1mm;
615 }
616
617 // Expand the garbage-first heap by at least the given size (in bytes!).
618 // Returns true if the heap was expanded by the requested amount;
619 // false otherwise.
620 // (Rounds up to a HeapRegion boundary.)
621 bool expand(size_t expand_bytes);
622
623 // Returns the PLAB statistics for a given destination.
624 inline PLABStats* alloc_buffer_stats(InCSetState dest);
625
626 // Determines PLAB size for a given destination.
627 inline size_t desired_plab_sz(InCSetState dest);
628
629 inline AllocationContextStats& allocation_context_stats();
630
631 // Do anything common to GC's.
632 void gc_prologue(bool full);
633 void gc_epilogue(bool full);
634
635 // Modify the reclaim candidate set and test for presence.
636 // These are only valid for starts_humongous regions.
637 inline void set_humongous_reclaim_candidate(uint region, bool value);
638 inline bool is_humongous_reclaim_candidate(uint region);
639
640 // Remove from the reclaim candidate set. Also remove from the
641 // collection set so that later encounters avoid the slow path.
642 inline void set_humongous_is_live(oop obj);
643
644 // Register the given region to be part of the collection set.
645 inline void register_humongous_region_with_cset(uint index);
646 // Register regions with humongous objects (actually on the start region) in
647 // the in_cset_fast_test table.
648 void register_humongous_regions_with_cset();
649 // We register a region with the fast "in collection set" test. We
650 // simply set to true the array slot corresponding to this region.
651 void register_young_region_with_cset(HeapRegion* r) {
652 _in_cset_fast_test.set_in_young(r->hrm_index());
653 }
654 void register_old_region_with_cset(HeapRegion* r) {
655 _in_cset_fast_test.set_in_old(r->hrm_index());
656 }
657 void clear_in_cset(const HeapRegion* hr) {
658 _in_cset_fast_test.clear(hr);
659 }
660
661 void clear_cset_fast_test() {
662 _in_cset_fast_test.clear();
663 }
664
665 // This is called at the start of either a concurrent cycle or a Full
666 // GC to update the number of old marking cycles started.
667 void increment_old_marking_cycles_started();
668
669 // This is called at the end of either a concurrent cycle or a Full
670 // GC to update the number of old marking cycles completed. Those two
671 // can happen in a nested fashion, i.e., we start a concurrent
672 // cycle, a Full GC happens half-way through it which ends first,
673 // and then the cycle notices that a Full GC happened and ends
674 // too. The concurrent parameter is a boolean to help us do a bit
675 // tighter consistency checking in the method. If concurrent is
676 // false, the caller is the inner caller in the nesting (i.e., the
677 // Full GC). If concurrent is true, the caller is the outer caller
678 // in this nesting (i.e., the concurrent cycle). Further nesting is
679 // not currently supported. The end of this call also notifies
680 // the FullGCCount_lock in case a Java thread is waiting for a full
681 // GC to happen (e.g., it called System.gc() with
682 // +ExplicitGCInvokesConcurrent).
683 void increment_old_marking_cycles_completed(bool concurrent);
684
685 uint old_marking_cycles_completed() {
686 return _old_marking_cycles_completed;
687 }
688
689 void register_concurrent_cycle_start(const Ticks& start_time);
690 void register_concurrent_cycle_end();
691 void trace_heap_after_concurrent_cycle();
692
693 G1HRPrinter* hr_printer() { return &_hr_printer; }
694
695 // Allocates a new heap region instance.
696 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr);
697
698 // Frees a non-humongous region by initializing its contents and
699 // adding it to the free list that's passed as a parameter (this is
700 // usually a local list which will be appended to the master free
701 // list later). The used bytes of freed regions are accumulated in
702 // pre_used. If par is true, the region's RSet will not be freed
703 // up. The assumption is that this will be done later.
704 // The locked parameter indicates if the caller has already taken
705 // care of proper synchronization. This may allow some optimizations.
706 void free_region(HeapRegion* hr,
707 FreeRegionList* free_list,
708 bool par,
709 bool locked = false);
710
711 // Frees a humongous region by collapsing it into individual regions
712 // and calling free_region() for each of them. The freed regions
713 // will be added to the free list that's passed as a parameter (this
714 // is 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 void free_humongous_region(HeapRegion* hr,
719 FreeRegionList* free_list,
720 bool par);
721
722 // Facility for allocating in 'archive' regions in high heap memory and
723 // recording the allocated ranges. These should all be called from the
724 // VM thread at safepoints, without the heap lock held. They can be used
725 // to create and archive a set of heap regions which can be mapped at the
726 // same fixed addresses in a subsequent JVM invocation.
727 void begin_archive_alloc_range();
728
729 // Check if the requested size would be too large for an archive allocation.
730 bool is_archive_alloc_too_large(size_t word_size);
731
732 // Allocate memory of the requested size from the archive region. This will
733 // return NULL if the size is too large or if no memory is available. It
734 // does not trigger a garbage collection.
735 HeapWord* archive_mem_allocate(size_t word_size);
736
737 // Optionally aligns the end address and returns the allocated ranges in
738 // an array of MemRegions in order of ascending addresses.
739 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
740 size_t end_alignment_in_bytes = 0);
741
742 // Facility for allocating a fixed range within the heap and marking
743 // the containing regions as 'archive'. For use at JVM init time, when the
744 // caller may mmap archived heap data at the specified range(s).
745 // Verify that the MemRegions specified in the argument array are within the
746 // reserved heap.
747 bool check_archive_addresses(MemRegion* range, size_t count);
748
749 // Commit the appropriate G1 regions containing the specified MemRegions
750 // and mark them as 'archive' regions. The regions in the array must be
751 // non-overlapping and in order of ascending address.
752 bool alloc_archive_regions(MemRegion* range, size_t count);
753
754 // Insert any required filler objects in the G1 regions around the specified
755 // ranges to make the regions parseable. This must be called after
756 // alloc_archive_regions, and after class loading has occurred.
757 void fill_archive_regions(MemRegion* range, size_t count);
758
759 protected:
760
761 // Shrink the garbage-first heap by at most the given size (in bytes!).
762 // (Rounds down to a HeapRegion boundary.)
763 virtual void shrink(size_t expand_bytes);
764 void shrink_helper(size_t expand_bytes);
765
766 #if TASKQUEUE_STATS
767 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
768 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
769 void reset_taskqueue_stats();
770 #endif // TASKQUEUE_STATS
771
772 // Schedule the VM operation that will do an evacuation pause to
773 // satisfy an allocation request of word_size. *succeeded will
774 // return whether the VM operation was successful (it did do an
775 // evacuation pause) or not (another thread beat us to it or the GC
776 // locker was active). Given that we should not be holding the
777 // Heap_lock when we enter this method, we will pass the
778 // gc_count_before (i.e., total_collections()) as a parameter since
779 // it has to be read while holding the Heap_lock. Currently, both
780 // methods that call do_collection_pause() release the Heap_lock
781 // before the call, so it's easy to read gc_count_before just before.
782 HeapWord* do_collection_pause(size_t word_size,
783 uint gc_count_before,
784 bool* succeeded,
785 GCCause::Cause gc_cause);
786
787 void wait_for_root_region_scanning();
788
789 // The guts of the incremental collection pause, executed by the vm
790 // thread. It returns false if it is unable to do the collection due
791 // to the GC locker being active, true otherwise
792 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
793
794 // Actually do the work of evacuating the collection set.
795 void evacuate_collection_set(EvacuationInfo& evacuation_info);
796
797 // The g1 remembered set of the heap.
798 G1RemSet* _g1_rem_set;
799
800 // A set of cards that cover the objects for which the Rsets should be updated
801 // concurrently after the collection.
802 DirtyCardQueueSet _dirty_card_queue_set;
803
804 // The closure used to refine a single card.
805 RefineCardTableEntryClosure* _refine_cte_cl;
806
807 // A DirtyCardQueueSet that is used to hold cards that contain
808 // references into the current collection set. This is used to
809 // update the remembered sets of the regions in the collection
810 // set in the event of an evacuation failure.
811 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
812
813 // After a collection pause, make the regions in the CS into free
814 // regions.
815 void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info);
816
817 // Abandon the current collection set without recording policy
818 // statistics or updating free lists.
819 void abandon_collection_set(HeapRegion* cs_head);
820
821 // The concurrent marker (and the thread it runs in.)
822 ConcurrentMark* _cm;
823 ConcurrentMarkThread* _cmThread;
824
825 // The concurrent refiner.
826 ConcurrentG1Refine* _cg1r;
827
828 // The parallel task queues
829 RefToScanQueueSet *_task_queues;
830
831 // True iff a evacuation has failed in the current collection.
832 bool _evacuation_failed;
833
834 EvacuationFailedInfo* _evacuation_failed_info_array;
835
836 // Failed evacuations cause some logical from-space objects to have
837 // forwarding pointers to themselves. Reset them.
838 void remove_self_forwarding_pointers();
839
840 struct OopAndMarkOop {
841 private:
842 oop _o;
843 markOop _m;
844 public:
845 OopAndMarkOop(oop obj, markOop m) : _o(obj), _m(m) {
846 }
847
848 void set_mark() {
849 _o->set_mark(_m);
850 }
851 };
852
853 typedef Stack<OopAndMarkOop,mtGC> OopAndMarkOopStack;
854 // Stores marks with the corresponding oop that we need to preserve during evacuation
855 // failure.
856 OopAndMarkOopStack* _preserved_objs;
857
858 // Preserve the mark of "obj", if necessary, in preparation for its mark
859 // word being overwritten with a self-forwarding-pointer.
860 void preserve_mark_during_evac_failure(uint queue, oop obj, markOop m);
861
862 #ifndef PRODUCT
863 // Support for forcing evacuation failures. Analogous to
864 // PromotionFailureALot for the other collectors.
865
866 // Records whether G1EvacuationFailureALot should be in effect
867 // for the current GC
868 bool _evacuation_failure_alot_for_current_gc;
869
870 // Used to record the GC number for interval checking when
871 // determining whether G1EvaucationFailureALot is in effect
872 // for the current GC.
873 size_t _evacuation_failure_alot_gc_number;
874
875 // Count of the number of evacuations between failures.
876 volatile size_t _evacuation_failure_alot_count;
877
878 // Set whether G1EvacuationFailureALot should be in effect
879 // for the current GC (based upon the type of GC and which
880 // command line flags are set);
881 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young,
882 bool during_initial_mark,
883 bool during_marking);
884
885 inline void set_evacuation_failure_alot_for_current_gc();
886
887 // Return true if it's time to cause an evacuation failure.
888 inline bool evacuation_should_fail();
889
890 // Reset the G1EvacuationFailureALot counters. Should be called at
891 // the end of an evacuation pause in which an evacuation failure occurred.
892 inline void reset_evacuation_should_fail();
893 #endif // !PRODUCT
894
895 // ("Weak") Reference processing support.
896 //
897 // G1 has 2 instances of the reference processor class. One
898 // (_ref_processor_cm) handles reference object discovery
899 // and subsequent processing during concurrent marking cycles.
900 //
901 // The other (_ref_processor_stw) handles reference object
902 // discovery and processing during full GCs and incremental
903 // evacuation pauses.
904 //
905 // During an incremental pause, reference discovery will be
906 // temporarily disabled for _ref_processor_cm and will be
907 // enabled for _ref_processor_stw. At the end of the evacuation
908 // pause references discovered by _ref_processor_stw will be
909 // processed and discovery will be disabled. The previous
910 // setting for reference object discovery for _ref_processor_cm
911 // will be re-instated.
912 //
913 // At the start of marking:
914 // * Discovery by the CM ref processor is verified to be inactive
915 // and it's discovered lists are empty.
916 // * Discovery by the CM ref processor is then enabled.
917 //
918 // At the end of marking:
919 // * Any references on the CM ref processor's discovered
920 // lists are processed (possibly MT).
921 //
922 // At the start of full GC we:
923 // * Disable discovery by the CM ref processor and
924 // empty CM ref processor's discovered lists
925 // (without processing any entries).
926 // * Verify that the STW ref processor is inactive and it's
927 // discovered lists are empty.
928 // * Temporarily set STW ref processor discovery as single threaded.
929 // * Temporarily clear the STW ref processor's _is_alive_non_header
930 // field.
931 // * Finally enable discovery by the STW ref processor.
932 //
933 // The STW ref processor is used to record any discovered
934 // references during the full GC.
935 //
936 // At the end of a full GC we:
937 // * Enqueue any reference objects discovered by the STW ref processor
938 // that have non-live referents. This has the side-effect of
939 // making the STW ref processor inactive by disabling discovery.
940 // * Verify that the CM ref processor is still inactive
941 // and no references have been placed on it's discovered
942 // lists (also checked as a precondition during initial marking).
943
944 // The (stw) reference processor...
945 ReferenceProcessor* _ref_processor_stw;
946
947 STWGCTimer* _gc_timer_stw;
948 ConcurrentGCTimer* _gc_timer_cm;
949
950 G1OldTracer* _gc_tracer_cm;
951 G1NewTracer* _gc_tracer_stw;
952
953 // During reference object discovery, the _is_alive_non_header
954 // closure (if non-null) is applied to the referent object to
955 // determine whether the referent is live. If so then the
956 // reference object does not need to be 'discovered' and can
957 // be treated as a regular oop. This has the benefit of reducing
958 // the number of 'discovered' reference objects that need to
959 // be processed.
960 //
961 // Instance of the is_alive closure for embedding into the
962 // STW reference processor as the _is_alive_non_header field.
963 // Supplying a value for the _is_alive_non_header field is
964 // optional but doing so prevents unnecessary additions to
965 // the discovered lists during reference discovery.
966 G1STWIsAliveClosure _is_alive_closure_stw;
967
968 // The (concurrent marking) reference processor...
969 ReferenceProcessor* _ref_processor_cm;
970
971 // Instance of the concurrent mark is_alive closure for embedding
972 // into the Concurrent Marking reference processor as the
973 // _is_alive_non_header field. Supplying a value for the
974 // _is_alive_non_header field is optional but doing so prevents
975 // unnecessary additions to the discovered lists during reference
976 // discovery.
977 G1CMIsAliveClosure _is_alive_closure_cm;
978
979 // Cache used by G1CollectedHeap::start_cset_region_for_worker().
980 HeapRegion** _worker_cset_start_region;
981
982 // Time stamp to validate the regions recorded in the cache
983 // used by G1CollectedHeap::start_cset_region_for_worker().
984 // The heap region entry for a given worker is valid iff
985 // the associated time stamp value matches the current value
986 // of G1CollectedHeap::_gc_time_stamp.
987 uint* _worker_cset_start_region_time_stamp;
988
989 volatile bool _free_regions_coming;
990
991 public:
992
993 void set_refine_cte_cl_concurrency(bool concurrent);
994
995 RefToScanQueue *task_queue(uint i) const;
996
997 uint num_task_queues() const;
998
999 // A set of cards where updates happened during the GC
1000 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
1001
1002 // A DirtyCardQueueSet that is used to hold cards that contain
1003 // references into the current collection set. This is used to
1004 // update the remembered sets of the regions in the collection
1005 // set in the event of an evacuation failure.
1006 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
1007 { return _into_cset_dirty_card_queue_set; }
1008
1009 // Create a G1CollectedHeap with the specified policy.
1010 // Must call the initialize method afterwards.
1011 // May not return if something goes wrong.
1012 G1CollectedHeap(G1CollectorPolicy* policy);
1013
1014 // Initialize the G1CollectedHeap to have the initial and
1015 // maximum sizes and remembered and barrier sets
1016 // specified by the policy object.
1017 jint initialize();
1018
1019 virtual void stop();
1020
1021 // Return the (conservative) maximum heap alignment for any G1 heap
1022 static size_t conservative_max_heap_alignment();
1023
1024 // Does operations required after initialization has been done.
1025 void post_initialize();
1026
1027 // Initialize weak reference processing.
1028 void ref_processing_init();
1029
1030 virtual Name kind() const {
1031 return CollectedHeap::G1CollectedHeap;
1032 }
1033
1034 G1CollectorState* collector_state() { return &_collector_state; }
1035
1036 // The current policy object for the collector.
1037 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
1038
1039 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); }
1040
1041 // Adaptive size policy. No such thing for g1.
1042 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
1043
1044 // The rem set and barrier set.
1045 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
1046
1047 unsigned get_gc_time_stamp() {
1048 return _gc_time_stamp;
1049 }
1050
1051 inline void reset_gc_time_stamp();
1052
1053 void check_gc_time_stamps() PRODUCT_RETURN;
1054
1055 inline void increment_gc_time_stamp();
1056
1057 // Reset the given region's GC timestamp. If it's starts humongous,
1058 // also reset the GC timestamp of its corresponding
1059 // continues humongous regions too.
1060 void reset_gc_time_stamps(HeapRegion* hr);
1061
1062 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
1063 DirtyCardQueue* into_cset_dcq,
1064 bool concurrent, uint worker_i);
1065
1066 // The shared block offset table array.
1067 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
1068
1069 // Reference Processing accessors
1070
1071 // The STW reference processor....
1072 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1073
1074 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; }
1075
1076 // The Concurrent Marking reference processor...
1077 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1078
1079 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; }
1080 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; }
1081
1082 virtual size_t capacity() const;
1083 virtual size_t used() const;
1084 // This should be called when we're not holding the heap lock. The
1085 // result might be a bit inaccurate.
1086 size_t used_unlocked() const;
1087 size_t recalculate_used() const;
1088
1089 // These virtual functions do the actual allocation.
1090 // Some heaps may offer a contiguous region for shared non-blocking
1091 // allocation, via inlined code (by exporting the address of the top and
1092 // end fields defining the extent of the contiguous allocation region.)
1093 // But G1CollectedHeap doesn't yet support this.
1094
1095 virtual bool is_maximal_no_gc() const {
1096 return _hrm.available() == 0;
1097 }
1098
1099 // The current number of regions in the heap.
1100 uint num_regions() const { return _hrm.length(); }
1101
1102 // The max number of regions in the heap.
1103 uint max_regions() const { return _hrm.max_length(); }
1104
1105 // The number of regions that are completely free.
1106 uint num_free_regions() const { return _hrm.num_free_regions(); }
1107
1108 MemoryUsage get_auxiliary_data_memory_usage() const {
1109 return _hrm.get_auxiliary_data_memory_usage();
1110 }
1111
1112 // The number of regions that are not completely free.
1113 uint num_used_regions() const { return num_regions() - num_free_regions(); }
1114
1115 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1116 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1117 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
1118 void verify_dirty_young_regions() PRODUCT_RETURN;
1119
1120 #ifndef PRODUCT
1121 // Make sure that the given bitmap has no marked objects in the
1122 // range [from,limit). If it does, print an error message and return
1123 // false. Otherwise, just return true. bitmap_name should be "prev"
1124 // or "next".
1125 bool verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
1126 HeapWord* from, HeapWord* limit);
1127
1128 // Verify that the prev / next bitmap range [tams,end) for the given
1129 // region has no marks. Return true if all is well, false if errors
1130 // are detected.
1131 bool verify_bitmaps(const char* caller, HeapRegion* hr);
1132 #endif // PRODUCT
1133
1134 // If G1VerifyBitmaps is set, verify that the marking bitmaps for
1135 // the given region do not have any spurious marks. If errors are
1136 // detected, print appropriate error messages and crash.
1137 void check_bitmaps(const char* caller, HeapRegion* hr) PRODUCT_RETURN;
1138
1139 // If G1VerifyBitmaps is set, verify that the marking bitmaps do not
1140 // have any spurious marks. If errors are detected, print
1141 // appropriate error messages and crash.
1142 void check_bitmaps(const char* caller) PRODUCT_RETURN;
1143
1144 // Do sanity check on the contents of the in-cset fast test table.
1145 bool check_cset_fast_test() PRODUCT_RETURN_( return true; );
1146
1147 // verify_region_sets() performs verification over the region
1148 // lists. It will be compiled in the product code to be used when
1149 // necessary (i.e., during heap verification).
1150 void verify_region_sets();
1151
1152 // verify_region_sets_optional() is planted in the code for
1153 // list verification in non-product builds (and it can be enabled in
1154 // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1).
1155 #if HEAP_REGION_SET_FORCE_VERIFY
1156 void verify_region_sets_optional() {
1157 verify_region_sets();
1158 }
1159 #else // HEAP_REGION_SET_FORCE_VERIFY
1160 void verify_region_sets_optional() { }
1161 #endif // HEAP_REGION_SET_FORCE_VERIFY
1162
1163 #ifdef ASSERT
1164 bool is_on_master_free_list(HeapRegion* hr) {
1165 return _hrm.is_free(hr);
1166 }
1167 #endif // ASSERT
1168
1169 // Wrapper for the region list operations that can be called from
1170 // methods outside this class.
1171
1172 void secondary_free_list_add(FreeRegionList* list) {
1173 _secondary_free_list.add_ordered(list);
1174 }
1175
1176 void append_secondary_free_list() {
1177 _hrm.insert_list_into_free_list(&_secondary_free_list);
1178 }
1179
1180 void append_secondary_free_list_if_not_empty_with_lock() {
1181 // If the secondary free list looks empty there's no reason to
1182 // take the lock and then try to append it.
1183 if (!_secondary_free_list.is_empty()) {
1184 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1185 append_secondary_free_list();
1186 }
1187 }
1188
1189 inline void old_set_remove(HeapRegion* hr);
1190
1191 size_t non_young_capacity_bytes() {
1192 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes();
1193 }
1194
1195 void set_free_regions_coming();
1196 void reset_free_regions_coming();
1197 bool free_regions_coming() { return _free_regions_coming; }
1198 void wait_while_free_regions_coming();
1199
1200 // Determine whether the given region is one that we are using as an
1201 // old GC alloc region.
1202 bool is_old_gc_alloc_region(HeapRegion* hr) {
1203 return _allocator->is_retained_old_region(hr);
1204 }
1205
1206 // Perform a collection of the heap; intended for use in implementing
1207 // "System.gc". This probably implies as full a collection as the
1208 // "CollectedHeap" supports.
1209 virtual void collect(GCCause::Cause cause);
1210
1211 // The same as above but assume that the caller holds the Heap_lock.
1212 void collect_locked(GCCause::Cause cause);
1213
1214 virtual bool copy_allocation_context_stats(const jint* contexts,
1215 jlong* totals,
1216 jbyte* accuracy,
1217 jint len);
1218
1219 // True iff an evacuation has failed in the most-recent collection.
1220 bool evacuation_failed() { return _evacuation_failed; }
1221
1222 void remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, const HeapRegionSetCount& humongous_regions_removed);
1223 void prepend_to_freelist(FreeRegionList* list);
1224 void decrement_summary_bytes(size_t bytes);
1225
1226 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1227 virtual bool is_in(const void* p) const;
1228 #ifdef ASSERT
1229 // Returns whether p is in one of the available areas of the heap. Slow but
1230 // extensive version.
1231 bool is_in_exact(const void* p) const;
1232 #endif
1233
1234 // Return "TRUE" iff the given object address is within the collection
1235 // set. Slow implementation.
1236 bool obj_in_cs(oop obj);
1237
1238 inline bool is_in_cset(const HeapRegion *hr);
1239 inline bool is_in_cset(oop obj);
1240
1241 inline bool is_in_cset_or_humongous(const oop obj);
1242
1243 private:
1244 // This array is used for a quick test on whether a reference points into
1245 // the collection set or not. Each of the array's elements denotes whether the
1246 // corresponding region is in the collection set or not.
1247 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test;
1248
1249 public:
1250
1251 inline InCSetState in_cset_state(const oop obj);
1252
1253 // Return "TRUE" iff the given object address is in the reserved
1254 // region of g1.
1255 bool is_in_g1_reserved(const void* p) const {
1256 return _hrm.reserved().contains(p);
1257 }
1258
1259 // Returns a MemRegion that corresponds to the space that has been
1260 // reserved for the heap
1261 MemRegion g1_reserved() const {
1262 return _hrm.reserved();
1263 }
1264
1265 virtual bool is_in_closed_subset(const void* p) const;
1266
1267 G1SATBCardTableLoggingModRefBS* g1_barrier_set() {
1268 return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set());
1269 }
1270
1271 // This resets the card table to all zeros. It is used after
1272 // a collection pause which used the card table to claim cards.
1273 void cleanUpCardTable();
1274
1275 // Iteration functions.
1276
1277 // Iterate over all objects, calling "cl.do_object" on each.
1278 virtual void object_iterate(ObjectClosure* cl);
1279
1280 virtual void safe_object_iterate(ObjectClosure* cl) {
1281 object_iterate(cl);
1282 }
1283
1284 // Iterate over heap regions, in address order, terminating the
1285 // iteration early if the "doHeapRegion" method returns "true".
1286 void heap_region_iterate(HeapRegionClosure* blk) const;
1287
1288 // Return the region with the given index. It assumes the index is valid.
1289 inline HeapRegion* region_at(uint index) const;
1290
1291 // Calculate the region index of the given address. Given address must be
1292 // within the heap.
1293 inline uint addr_to_region(HeapWord* addr) const;
1294
1295 inline HeapWord* bottom_addr_for_region(uint index) const;
1296
1297 // Iterate over the heap regions in parallel. Assumes that this will be called
1298 // in parallel by ParallelGCThreads worker threads with distinct worker ids
1299 // in the range [0..max(ParallelGCThreads-1, 1)]. Applies "blk->doHeapRegion"
1300 // to each of the regions, by attempting to claim the region using the
1301 // HeapRegionClaimer and, if successful, applying the closure to the claimed
1302 // region. The concurrent argument should be set to true if iteration is
1303 // performed concurrently, during which no assumptions are made for consistent
1304 // attributes of the heap regions (as they might be modified while iterating).
1305 void heap_region_par_iterate(HeapRegionClosure* cl,
1306 uint worker_id,
1307 HeapRegionClaimer* hrclaimer,
1308 bool concurrent = false) const;
1309
1310 // Clear the cached cset start regions and (more importantly)
1311 // the time stamps. Called when we reset the GC time stamp.
1312 void clear_cset_start_regions();
1313
1314 // Given the id of a worker, obtain or calculate a suitable
1315 // starting region for iterating over the current collection set.
1316 HeapRegion* start_cset_region_for_worker(uint worker_i);
1317
1318 // Iterate over the regions (if any) in the current collection set.
1319 void collection_set_iterate(HeapRegionClosure* blk);
1320
1321 // As above but starting from region r
1322 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1323
1324 HeapRegion* next_compaction_region(const HeapRegion* from) const;
1325
1326 // Returns the HeapRegion that contains addr. addr must not be NULL.
1327 template <class T>
1328 inline HeapRegion* heap_region_containing_raw(const T addr) const;
1329
1330 // Returns the HeapRegion that contains addr. addr must not be NULL.
1331 // If addr is within a humongous continues region, it returns its humongous start region.
1332 template <class T>
1333 inline HeapRegion* heap_region_containing(const T addr) const;
1334
1335 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1336 // each address in the (reserved) heap is a member of exactly
1337 // one block. The defining characteristic of a block is that it is
1338 // possible to find its size, and thus to progress forward to the next
1339 // block. (Blocks may be of different sizes.) Thus, blocks may
1340 // represent Java objects, or they might be free blocks in a
1341 // free-list-based heap (or subheap), as long as the two kinds are
1342 // distinguishable and the size of each is determinable.
1343
1344 // Returns the address of the start of the "block" that contains the
1345 // address "addr". We say "blocks" instead of "object" since some heaps
1346 // may not pack objects densely; a chunk may either be an object or a
1347 // non-object.
1348 virtual HeapWord* block_start(const void* addr) const;
1349
1350 // Requires "addr" to be the start of a chunk, and returns its size.
1351 // "addr + size" is required to be the start of a new chunk, or the end
1352 // of the active area of the heap.
1353 virtual size_t block_size(const HeapWord* addr) const;
1354
1355 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1356 // the block is an object.
1357 virtual bool block_is_obj(const HeapWord* addr) const;
1358
1359 // Section on thread-local allocation buffers (TLABs)
1360 // See CollectedHeap for semantics.
1361
1362 bool supports_tlab_allocation() const;
1363 size_t tlab_capacity(Thread* ignored) const;
1364 size_t tlab_used(Thread* ignored) const;
1365 size_t max_tlab_size() const;
1366 size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1367
1368 // Can a compiler initialize a new object without store barriers?
1369 // This permission only extends from the creation of a new object
1370 // via a TLAB up to the first subsequent safepoint. If such permission
1371 // is granted for this heap type, the compiler promises to call
1372 // defer_store_barrier() below on any slow path allocation of
1373 // a new object for which such initializing store barriers will
1374 // have been elided. G1, like CMS, allows this, but should be
1375 // ready to provide a compensating write barrier as necessary
1376 // if that storage came out of a non-young region. The efficiency
1377 // of this implementation depends crucially on being able to
1378 // answer very efficiently in constant time whether a piece of
1379 // storage in the heap comes from a young region or not.
1380 // See ReduceInitialCardMarks.
1381 virtual bool can_elide_tlab_store_barriers() const {
1382 return true;
1383 }
1384
1385 virtual bool card_mark_must_follow_store() const {
1386 return true;
1387 }
1388
1389 inline bool is_in_young(const oop obj);
1390
1391 virtual bool is_scavengable(const void* addr);
1392
1393 // We don't need barriers for initializing stores to objects
1394 // in the young gen: for the SATB pre-barrier, there is no
1395 // pre-value that needs to be remembered; for the remembered-set
1396 // update logging post-barrier, we don't maintain remembered set
1397 // information for young gen objects.
1398 virtual inline bool can_elide_initializing_store_barrier(oop new_obj);
1399
1400 // Returns "true" iff the given word_size is "very large".
1401 static bool is_humongous(size_t word_size) {
1402 // Note this has to be strictly greater-than as the TLABs
1403 // are capped at the humongous threshold and we want to
1404 // ensure that we don't try to allocate a TLAB as
1405 // humongous and that we don't allocate a humongous
1406 // object in a TLAB.
1407 return word_size > _humongous_object_threshold_in_words;
1408 }
1409
1410 // Returns the humongous threshold for a specific region size
1411 static size_t humongous_threshold_for(size_t region_size) {
1412 return (region_size / 2);
1413 }
1414
1415 // Update mod union table with the set of dirty cards.
1416 void updateModUnion();
1417
1418 // Set the mod union bits corresponding to the given memRegion. Note
1419 // that this is always a safe operation, since it doesn't clear any
1420 // bits.
1421 void markModUnionRange(MemRegion mr);
1422
1423 // Print the maximum heap capacity.
1424 virtual size_t max_capacity() const;
1425
1426 virtual jlong millis_since_last_gc();
1427
1428
1429 // Convenience function to be used in situations where the heap type can be
1430 // asserted to be this type.
1431 static G1CollectedHeap* heap();
1432
1433 void set_region_short_lived_locked(HeapRegion* hr);
1434 // add appropriate methods for any other surv rate groups
1435
1436 YoungList* young_list() const { return _young_list; }
1437
1438 // debugging
1439 bool check_young_list_well_formed() {
1440 return _young_list->check_list_well_formed();
1441 }
1442
1443 bool check_young_list_empty(bool check_heap,
1444 bool check_sample = true);
1445
1446 // *** Stuff related to concurrent marking. It's not clear to me that so
1447 // many of these need to be public.
1448
1449 // The functions below are helper functions that a subclass of
1450 // "CollectedHeap" can use in the implementation of its virtual
1451 // functions.
1452 // This performs a concurrent marking of the live objects in a
1453 // bitmap off to the side.
1454 void doConcurrentMark();
1455
1456 bool isMarkedPrev(oop obj) const;
1457 bool isMarkedNext(oop obj) const;
1458
1459 // Determine if an object is dead, given the object and also
1460 // the region to which the object belongs. An object is dead
1461 // iff a) it was not allocated since the last mark, b) it
1462 // is not marked, and c) it is not in an archive region.
1463 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1464 return
1465 !hr->obj_allocated_since_prev_marking(obj) &&
1466 !isMarkedPrev(obj) &&
1467 !hr->is_archive();
1468 }
1469
1470 // This function returns true when an object has been
1471 // around since the previous marking and hasn't yet
1472 // been marked during this marking, and is not in an archive region.
1473 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1474 return
1475 !hr->obj_allocated_since_next_marking(obj) &&
1476 !isMarkedNext(obj) &&
1477 !hr->is_archive();
1478 }
1479
1480 // Determine if an object is dead, given only the object itself.
1481 // This will find the region to which the object belongs and
1482 // then call the region version of the same function.
1483
1484 // Added if it is NULL it isn't dead.
1485
1486 inline bool is_obj_dead(const oop obj) const;
1487
1488 inline bool is_obj_ill(const oop obj) const;
1489
1490 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo);
1491 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo);
1492 bool is_marked(oop obj, VerifyOption vo);
1493 const char* top_at_mark_start_str(VerifyOption vo);
1494
1495 ConcurrentMark* concurrent_mark() const { return _cm; }
1496
1497 // Refinement
1498
1499 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1500
1501 // The dirty cards region list is used to record a subset of regions
1502 // whose cards need clearing. The list if populated during the
1503 // remembered set scanning and drained during the card table
1504 // cleanup. Although the methods are reentrant, population/draining
1505 // phases must not overlap. For synchronization purposes the last
1506 // element on the list points to itself.
1507 HeapRegion* _dirty_cards_region_list;
1508 void push_dirty_cards_region(HeapRegion* hr);
1509 HeapRegion* pop_dirty_cards_region();
1510
1511 // Optimized nmethod scanning support routines
1512
1513 // Register the given nmethod with the G1 heap.
1514 virtual void register_nmethod(nmethod* nm);
1515
1516 // Unregister the given nmethod from the G1 heap.
1517 virtual void unregister_nmethod(nmethod* nm);
1518
1519 // Free up superfluous code root memory.
1520 void purge_code_root_memory();
1521
1522 // Rebuild the strong code root lists for each region
1523 // after a full GC.
1524 void rebuild_strong_code_roots();
1525
1526 // Delete entries for dead interned string and clean up unreferenced symbols
1527 // in symbol table, possibly in parallel.
1528 void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true);
1529
1530 // Parallel phase of unloading/cleaning after G1 concurrent mark.
1531 void parallel_cleaning(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool class_unloading_occurred);
1532
1533 // Redirty logged cards in the refinement queue.
1534 void redirty_logged_cards();
1535 // Verification
1536
1537 // Perform any cleanup actions necessary before allowing a verification.
1538 virtual void prepare_for_verify();
1539
1540 // Perform verification.
1541
1542 // vo == UsePrevMarking -> use "prev" marking information,
1543 // vo == UseNextMarking -> use "next" marking information
1544 // vo == UseMarkWord -> use the mark word in the object header
1545 //
1546 // NOTE: Only the "prev" marking information is guaranteed to be
1547 // consistent most of the time, so most calls to this should use
1548 // vo == UsePrevMarking.
1549 // Currently, there is only one case where this is called with
1550 // vo == UseNextMarking, which is to verify the "next" marking
1551 // information at the end of remark.
1552 // Currently there is only one place where this is called with
1553 // vo == UseMarkWord, which is to verify the marking during a
1554 // full GC.
1555 void verify(bool silent, VerifyOption vo);
1556
1557 // Override; it uses the "prev" marking information
1558 virtual void verify(bool silent);
1559
1560 // The methods below are here for convenience and dispatch the
1561 // appropriate method depending on value of the given VerifyOption
1562 // parameter. The values for that parameter, and their meanings,
1563 // are the same as those above.
1564
1565 bool is_obj_dead_cond(const oop obj,
1566 const HeapRegion* hr,
1567 const VerifyOption vo) const;
1568
1569 bool is_obj_dead_cond(const oop obj,
1570 const VerifyOption vo) const;
1571
1572 G1HeapSummary create_g1_heap_summary();
1573
1574 // Printing
1575
1576 virtual void print_on(outputStream* st) const;
1577 virtual void print_extended_on(outputStream* st) const;
1578 virtual void print_on_error(outputStream* st) const;
1579
1580 virtual void print_gc_threads_on(outputStream* st) const;
1581 virtual void gc_threads_do(ThreadClosure* tc) const;
1582
1583 // Override
1584 void print_tracing_info() const;
1585
1586 // The following two methods are helpful for debugging RSet issues.
1587 void print_cset_rsets() PRODUCT_RETURN;
1588 void print_all_rsets() PRODUCT_RETURN;
1589
1590 public:
1591 size_t pending_card_num();
1592 size_t cards_scanned();
1593
1594 protected:
1595 size_t _max_heap_capacity;
1596 };
1597
1598 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP