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.
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5 * This code is free software; you can redistribute it and/or modify it
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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24
25 #ifndef SHARE_VM_GC_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 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
79 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue;
80 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
81
82 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
83 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
84
85 class YoungList : public CHeapObj<mtGC> {
86 private:
87 G1CollectedHeap* _g1h;
88
89 HeapRegion* _head;
90
91 HeapRegion* _survivor_head;
92 HeapRegion* _survivor_tail;
93
94 HeapRegion* _curr;
95
96 uint _length;
97 uint _survivor_length;
98
99 size_t _last_sampled_rs_lengths;
100 size_t _sampled_rs_lengths;
101
102 void empty_list(HeapRegion* list);
103
104 public:
105 YoungList(G1CollectedHeap* g1h);
106
107 void push_region(HeapRegion* hr);
108 void add_survivor_region(HeapRegion* hr);
109
110 void empty_list();
111 bool is_empty() { return _length == 0; }
112 uint length() { return _length; }
113 uint survivor_length() { return _survivor_length; }
114
115 // Currently we do not keep track of the used byte sum for the
116 // young list and the survivors and it'd be quite a lot of work to
117 // do so. When we'll eventually replace the young list with
118 // instances of HeapRegionLinkedList we'll get that for free. So,
119 // we'll report the more accurate information then.
120 size_t eden_used_bytes() {
121 assert(length() >= survivor_length(), "invariant");
122 return (size_t) (length() - survivor_length()) * HeapRegion::GrainBytes;
123 }
124 size_t survivor_used_bytes() {
125 return (size_t) survivor_length() * HeapRegion::GrainBytes;
126 }
127
128 void rs_length_sampling_init();
129 bool rs_length_sampling_more();
130 void rs_length_sampling_next();
131
132 void reset_sampled_info() {
133 _last_sampled_rs_lengths = 0;
134 }
135 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }
136
137 // for development purposes
138 void reset_auxilary_lists();
139 void clear() { _head = NULL; _length = 0; }
140
141 void clear_survivors() {
142 _survivor_head = NULL;
143 _survivor_tail = NULL;
144 _survivor_length = 0;
145 }
146
147 HeapRegion* first_region() { return _head; }
148 HeapRegion* first_survivor_region() { return _survivor_head; }
149 HeapRegion* last_survivor_region() { return _survivor_tail; }
150
151 // debugging
152 bool check_list_well_formed();
153 bool check_list_empty(bool check_sample = true);
154 void print();
155 };
156
157 // The G1 STW is alive closure.
158 // An instance is embedded into the G1CH and used as the
159 // (optional) _is_alive_non_header closure in the STW
160 // reference processor. It is also extensively used during
161 // reference processing during STW evacuation pauses.
162 class G1STWIsAliveClosure: public BoolObjectClosure {
163 G1CollectedHeap* _g1;
164 public:
165 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
166 bool do_object_b(oop p);
167 };
168
169 class RefineCardTableEntryClosure;
170
171 class G1RegionMappingChangedListener : public G1MappingChangedListener {
172 private:
173 void reset_from_card_cache(uint start_idx, size_t num_regions);
174 public:
175 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
176 };
177
178 class G1CollectedHeap : public SharedHeap {
179 friend class VM_CollectForMetadataAllocation;
180 friend class VM_G1CollectForAllocation;
181 friend class VM_G1CollectFull;
182 friend class VM_G1IncCollectionPause;
183 friend class VMStructs;
184 friend class MutatorAllocRegion;
185 friend class SurvivorGCAllocRegion;
186 friend class OldGCAllocRegion;
187 friend class G1Allocator;
188
189 // Closures used in implementation.
190 friend class G1ParScanThreadState;
191 friend class G1ParTask;
192 friend class G1PLABAllocator;
193 friend class G1PrepareCompactClosure;
194
195 // Other related classes.
196 friend class HeapRegionClaimer;
197
198 // Testing classes.
199 friend class G1CheckCSetFastTableClosure;
200
201 private:
202 // The one and only G1CollectedHeap, so static functions can find it.
203 static G1CollectedHeap* _g1h;
204
205 static size_t _humongous_object_threshold_in_words;
206
207 // The secondary free list which contains regions that have been
208 // freed up during the cleanup process. This will be appended to
209 // the master free list when appropriate.
210 FreeRegionList _secondary_free_list;
211
212 // It keeps track of the old regions.
213 HeapRegionSet _old_set;
214
215 // It keeps track of the humongous regions.
216 HeapRegionSet _humongous_set;
217
218 void clear_humongous_is_live_table();
219 void eagerly_reclaim_humongous_regions();
220
221 // The number of regions we could create by expansion.
222 uint _expansion_regions;
223
224 // The block offset table for the G1 heap.
225 G1BlockOffsetSharedArray* _bot_shared;
226
227 // Tears down the region sets / lists so that they are empty and the
228 // regions on the heap do not belong to a region set / list. The
229 // only exception is the humongous set which we leave unaltered. If
230 // free_list_only is true, it will only tear down the master free
231 // list. It is called before a Full GC (free_list_only == false) or
232 // before heap shrinking (free_list_only == true).
233 void tear_down_region_sets(bool free_list_only);
234
235 // Rebuilds the region sets / lists so that they are repopulated to
236 // reflect the contents of the heap. The only exception is the
237 // humongous set which was not torn down in the first place. If
238 // free_list_only is true, it will only rebuild the master free
239 // list. It is called after a Full GC (free_list_only == false) or
240 // after heap shrinking (free_list_only == true).
241 void rebuild_region_sets(bool free_list_only);
242
243 // Callback for region mapping changed events.
244 G1RegionMappingChangedListener _listener;
245
246 // The sequence of all heap regions in the heap.
247 HeapRegionManager _hrm;
248
249 // Handles the different kinds of allocations within a region.
250 G1Allocator* _allocator;
251
252 // Outside of GC pauses, the number of bytes used in all regions other
253 // than the current allocation region(s).
254 size_t _summary_bytes_used;
255
256 // Statistics for each allocation context
257 AllocationContextStats _allocation_context_stats;
258
259 // PLAB sizing policy for survivors.
260 PLABStats _survivor_plab_stats;
261
262 // PLAB sizing policy for tenured objects.
263 PLABStats _old_plab_stats;
264
265 // It specifies whether we should attempt to expand the heap after a
266 // region allocation failure. If heap expansion fails we set this to
267 // false so that we don't re-attempt the heap expansion (it's likely
268 // that subsequent expansion attempts will also fail if one fails).
269 // Currently, it is only consulted during GC and it's reset at the
270 // start of each GC.
271 bool _expand_heap_after_alloc_failure;
272
273 // Helper for monitoring and management support.
274 G1MonitoringSupport* _g1mm;
275
276 // Records whether the region at the given index is kept live by roots or
277 // references from the young generation.
278 class HumongousIsLiveBiasedMappedArray : public G1BiasedMappedArray<bool> {
279 protected:
280 bool default_value() const { return false; }
281 public:
282 void clear() { G1BiasedMappedArray<bool>::clear(); }
283 void set_live(uint region) {
284 set_by_index(region, true);
285 }
286 bool is_live(uint region) {
287 return get_by_index(region);
288 }
289 };
290
291 HumongousIsLiveBiasedMappedArray _humongous_is_live;
292 // Stores whether during humongous object registration we found candidate regions.
293 // If not, we can skip a few steps.
294 bool _has_humongous_reclaim_candidates;
295
296 volatile unsigned _gc_time_stamp;
297
298 size_t* _surviving_young_words;
299
300 G1HRPrinter _hr_printer;
301
302 void setup_surviving_young_words();
303 void update_surviving_young_words(size_t* surv_young_words);
304 void cleanup_surviving_young_words();
305
306 // It decides whether an explicit GC should start a concurrent cycle
307 // instead of doing a STW GC. Currently, a concurrent cycle is
308 // explicitly started if:
309 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
310 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
311 // (c) cause == _g1_humongous_allocation
312 bool should_do_concurrent_full_gc(GCCause::Cause cause);
313
314 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
315 // concurrent cycles) we have started.
316 volatile uint _old_marking_cycles_started;
317
318 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
319 // concurrent cycles) we have completed.
320 volatile uint _old_marking_cycles_completed;
321
322 bool _concurrent_cycle_started;
323 bool _heap_summary_sent;
324
325 // This is a non-product method that is helpful for testing. It is
326 // called at the end of a GC and artificially expands the heap by
327 // allocating a number of dead regions. This way we can induce very
328 // frequent marking cycles and stress the cleanup / concurrent
329 // cleanup code more (as all the regions that will be allocated by
330 // this method will be found dead by the marking cycle).
331 void allocate_dummy_regions() PRODUCT_RETURN;
332
333 // Clear RSets after a compaction. It also resets the GC time stamps.
334 void clear_rsets_post_compaction();
335
336 // If the HR printer is active, dump the state of the regions in the
337 // heap after a compaction.
338 void print_hrm_post_compaction();
339
340 double verify(bool guard, const char* msg);
341 void verify_before_gc();
342 void verify_after_gc();
343
344 void log_gc_header();
345 void log_gc_footer(double pause_time_sec);
346
347 // These are macros so that, if the assert fires, we get the correct
348 // line number, file, etc.
349
350 #define heap_locking_asserts_err_msg(_extra_message_) \
351 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
352 (_extra_message_), \
353 BOOL_TO_STR(Heap_lock->owned_by_self()), \
354 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
355 BOOL_TO_STR(Thread::current()->is_VM_thread()))
356
357 #define assert_heap_locked() \
358 do { \
359 assert(Heap_lock->owned_by_self(), \
360 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
361 } while (0)
362
363 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
364 do { \
365 assert(Heap_lock->owned_by_self() || \
366 (SafepointSynchronize::is_at_safepoint() && \
367 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
368 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
369 "should be at a safepoint")); \
370 } while (0)
371
372 #define assert_heap_locked_and_not_at_safepoint() \
373 do { \
374 assert(Heap_lock->owned_by_self() && \
375 !SafepointSynchronize::is_at_safepoint(), \
376 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
377 "should not be at a safepoint")); \
378 } while (0)
379
380 #define assert_heap_not_locked() \
381 do { \
382 assert(!Heap_lock->owned_by_self(), \
383 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
384 } while (0)
385
386 #define assert_heap_not_locked_and_not_at_safepoint() \
387 do { \
388 assert(!Heap_lock->owned_by_self() && \
389 !SafepointSynchronize::is_at_safepoint(), \
390 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
391 "should not be at a safepoint")); \
392 } while (0)
393
394 #define assert_at_safepoint(_should_be_vm_thread_) \
395 do { \
396 assert(SafepointSynchronize::is_at_safepoint() && \
397 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
398 heap_locking_asserts_err_msg("should be at a safepoint")); \
399 } while (0)
400
401 #define assert_not_at_safepoint() \
402 do { \
403 assert(!SafepointSynchronize::is_at_safepoint(), \
404 heap_locking_asserts_err_msg("should not be at a safepoint")); \
405 } while (0)
406
407 protected:
408
409 // The young region list.
410 YoungList* _young_list;
411
412 // The current policy object for the collector.
413 G1CollectorPolicy* _g1_policy;
414
415 // This is the second level of trying to allocate a new region. If
416 // new_region() didn't find a region on the free_list, this call will
417 // check whether there's anything available on the
418 // secondary_free_list and/or wait for more regions to appear on
419 // that list, if _free_regions_coming is set.
420 HeapRegion* new_region_try_secondary_free_list(bool is_old);
421
422 // Try to allocate a single non-humongous HeapRegion sufficient for
423 // an allocation of the given word_size. If do_expand is true,
424 // attempt to expand the heap if necessary to satisfy the allocation
425 // request. If the region is to be used as an old region or for a
426 // humongous object, set is_old to true. If not, to false.
427 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand);
428
429 // Initialize a contiguous set of free regions of length num_regions
430 // and starting at index first so that they appear as a single
431 // humongous region.
432 HeapWord* humongous_obj_allocate_initialize_regions(uint first,
433 uint num_regions,
434 size_t word_size,
435 AllocationContext_t context);
436
437 // Attempt to allocate a humongous object of the given size. Return
438 // NULL if unsuccessful.
439 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context);
440
441 // The following two methods, allocate_new_tlab() and
442 // mem_allocate(), are the two main entry points from the runtime
443 // into the G1's allocation routines. They have the following
444 // assumptions:
445 //
446 // * They should both be called outside safepoints.
447 //
448 // * They should both be called without holding the Heap_lock.
449 //
450 // * All allocation requests for new TLABs should go to
451 // allocate_new_tlab().
452 //
453 // * All non-TLAB allocation requests should go to mem_allocate().
454 //
455 // * If either call cannot satisfy the allocation request using the
456 // current allocating region, they will try to get a new one. If
457 // this fails, they will attempt to do an evacuation pause and
458 // retry the allocation.
459 //
460 // * If all allocation attempts fail, even after trying to schedule
461 // an evacuation pause, allocate_new_tlab() will return NULL,
462 // whereas mem_allocate() will attempt a heap expansion and/or
463 // schedule a Full GC.
464 //
465 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
466 // should never be called with word_size being humongous. All
467 // humongous allocation requests should go to mem_allocate() which
468 // will satisfy them with a special path.
469
470 virtual HeapWord* allocate_new_tlab(size_t word_size);
471
472 virtual HeapWord* mem_allocate(size_t word_size,
473 bool* gc_overhead_limit_was_exceeded);
474
475 // The following three methods take a gc_count_before_ret
476 // parameter which is used to return the GC count if the method
477 // returns NULL. Given that we are required to read the GC count
478 // while holding the Heap_lock, and these paths will take the
479 // Heap_lock at some point, it's easier to get them to read the GC
480 // count while holding the Heap_lock before they return NULL instead
481 // of the caller (namely: mem_allocate()) having to also take the
482 // Heap_lock just to read the GC count.
483
484 // First-level mutator allocation attempt: try to allocate out of
485 // the mutator alloc region without taking the Heap_lock. This
486 // should only be used for non-humongous allocations.
487 inline HeapWord* attempt_allocation(size_t word_size,
488 uint* gc_count_before_ret,
489 uint* gclocker_retry_count_ret);
490
491 // Second-level mutator allocation attempt: take the Heap_lock and
492 // retry the allocation attempt, potentially scheduling a GC
493 // pause. This should only be used for non-humongous allocations.
494 HeapWord* attempt_allocation_slow(size_t word_size,
495 AllocationContext_t context,
496 uint* gc_count_before_ret,
497 uint* gclocker_retry_count_ret);
498
499 // Takes the Heap_lock and attempts a humongous allocation. It can
500 // potentially schedule a GC pause.
501 HeapWord* attempt_allocation_humongous(size_t word_size,
502 uint* gc_count_before_ret,
503 uint* gclocker_retry_count_ret);
504
505 // Allocation attempt that should be called during safepoints (e.g.,
506 // at the end of a successful GC). expect_null_mutator_alloc_region
507 // specifies whether the mutator alloc region is expected to be NULL
508 // or not.
509 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
510 AllocationContext_t context,
511 bool expect_null_mutator_alloc_region);
512
513 // It dirties the cards that cover the block so that so that the post
514 // write barrier never queues anything when updating objects on this
515 // block. It is assumed (and in fact we assert) that the block
516 // belongs to a young region.
517 inline void dirty_young_block(HeapWord* start, size_t word_size);
518
519 // Allocate blocks during garbage collection. Will ensure an
520 // allocation region, either by picking one or expanding the
521 // heap, and then allocate a block of the given size. The block
522 // may not be a humongous - it must fit into a single heap region.
523 inline HeapWord* par_allocate_during_gc(InCSetState dest,
524 size_t word_size,
525 AllocationContext_t context);
526 // Ensure that no further allocations can happen in "r", bearing in mind
527 // that parallel threads might be attempting allocations.
528 void par_allocate_remaining_space(HeapRegion* r);
529
530 // Allocation attempt during GC for a survivor object / PLAB.
531 inline HeapWord* survivor_attempt_allocation(size_t word_size,
532 AllocationContext_t context);
533
534 // Allocation attempt during GC for an old object / PLAB.
535 inline HeapWord* old_attempt_allocation(size_t word_size,
536 AllocationContext_t context);
537
538 // These methods are the "callbacks" from the G1AllocRegion class.
539
540 // For mutator alloc regions.
541 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
542 void retire_mutator_alloc_region(HeapRegion* alloc_region,
543 size_t allocated_bytes);
544
545 // For GC alloc regions.
546 HeapRegion* new_gc_alloc_region(size_t word_size, uint count,
547 InCSetState dest);
548 void retire_gc_alloc_region(HeapRegion* alloc_region,
549 size_t allocated_bytes, InCSetState dest);
550
551 // - if explicit_gc is true, the GC is for a System.gc() or a heap
552 // inspection request and should collect the entire heap
553 // - if clear_all_soft_refs is true, all soft references should be
554 // cleared during the GC
555 // - if explicit_gc is false, word_size describes the allocation that
556 // the GC should attempt (at least) to satisfy
557 // - it returns false if it is unable to do the collection due to the
558 // GC locker being active, true otherwise
559 bool do_collection(bool explicit_gc,
560 bool clear_all_soft_refs,
561 size_t word_size);
562
563 // Callback from VM_G1CollectFull operation.
564 // Perform a full collection.
565 virtual void do_full_collection(bool clear_all_soft_refs);
566
567 // Resize the heap if necessary after a full collection. If this is
568 // after a collect-for allocation, "word_size" is the allocation size,
569 // and will be considered part of the used portion of the heap.
570 void resize_if_necessary_after_full_collection(size_t word_size);
571
572 // Callback from VM_G1CollectForAllocation operation.
573 // This function does everything necessary/possible to satisfy a
574 // failed allocation request (including collection, expansion, etc.)
575 HeapWord* satisfy_failed_allocation(size_t word_size,
576 AllocationContext_t context,
577 bool* succeeded);
578
579 // Attempting to expand the heap sufficiently
580 // to support an allocation of the given "word_size". If
581 // successful, perform the allocation and return the address of the
582 // allocated block, or else "NULL".
583 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context);
584
585 // Process any reference objects discovered during
586 // an incremental evacuation pause.
587 void process_discovered_references(uint no_of_gc_workers);
588
589 // Enqueue any remaining discovered references
590 // after processing.
591 void enqueue_discovered_references(uint no_of_gc_workers);
592
593 public:
594
595 G1Allocator* allocator() {
596 return _allocator;
597 }
598
599 G1MonitoringSupport* g1mm() {
600 assert(_g1mm != NULL, "should have been initialized");
601 return _g1mm;
602 }
603
604 // Expand the garbage-first heap by at least the given size (in bytes!).
605 // Returns true if the heap was expanded by the requested amount;
606 // false otherwise.
607 // (Rounds up to a HeapRegion boundary.)
608 bool expand(size_t expand_bytes);
609
610 // Returns the PLAB statistics for a given destination.
611 inline PLABStats* alloc_buffer_stats(InCSetState dest);
612
613 // Determines PLAB size for a given destination.
614 inline size_t desired_plab_sz(InCSetState dest);
615
616 inline AllocationContextStats& allocation_context_stats();
617
618 // Do anything common to GC's.
619 virtual void gc_prologue(bool full);
620 virtual void gc_epilogue(bool full);
621
622 inline void set_humongous_is_live(oop obj);
623
624 bool humongous_is_live(uint region) {
625 return _humongous_is_live.is_live(region);
626 }
627
628 // Returns whether the given region (which must be a humongous (start) region)
629 // is to be considered conservatively live regardless of any other conditions.
630 bool humongous_region_is_always_live(uint index);
631 // Returns whether the given region (which must be a humongous (start) region)
632 // is considered a candidate for eager reclamation.
633 bool humongous_region_is_candidate(uint index);
634 // Register the given region to be part of the collection set.
635 inline void register_humongous_region_with_in_cset_fast_test(uint index);
636 // Register regions with humongous objects (actually on the start region) in
637 // the in_cset_fast_test table.
638 void register_humongous_regions_with_in_cset_fast_test();
639 // We register a region with the fast "in collection set" test. We
640 // simply set to true the array slot corresponding to this region.
641 void register_young_region_with_in_cset_fast_test(HeapRegion* r) {
642 _in_cset_fast_test.set_in_young(r->hrm_index());
643 }
644 void register_old_region_with_in_cset_fast_test(HeapRegion* r) {
645 _in_cset_fast_test.set_in_old(r->hrm_index());
646 }
647
648 // This is a fast test on whether a reference points into the
649 // collection set or not. Assume that the reference
650 // points into the heap.
651 inline bool in_cset_fast_test(oop obj);
652
653 void clear_cset_fast_test() {
654 _in_cset_fast_test.clear();
655 }
656
657 // This is called at the start of either a concurrent cycle or a Full
658 // GC to update the number of old marking cycles started.
659 void increment_old_marking_cycles_started();
660
661 // This is called at the end of either a concurrent cycle or a Full
662 // GC to update the number of old marking cycles completed. Those two
663 // can happen in a nested fashion, i.e., we start a concurrent
664 // cycle, a Full GC happens half-way through it which ends first,
665 // and then the cycle notices that a Full GC happened and ends
666 // too. The concurrent parameter is a boolean to help us do a bit
667 // tighter consistency checking in the method. If concurrent is
668 // false, the caller is the inner caller in the nesting (i.e., the
669 // Full GC). If concurrent is true, the caller is the outer caller
670 // in this nesting (i.e., the concurrent cycle). Further nesting is
671 // not currently supported. The end of this call also notifies
672 // the FullGCCount_lock in case a Java thread is waiting for a full
673 // GC to happen (e.g., it called System.gc() with
674 // +ExplicitGCInvokesConcurrent).
675 void increment_old_marking_cycles_completed(bool concurrent);
676
677 uint old_marking_cycles_completed() {
678 return _old_marking_cycles_completed;
679 }
680
681 void register_concurrent_cycle_start(const Ticks& start_time);
682 void register_concurrent_cycle_end();
683 void trace_heap_after_concurrent_cycle();
684
685 G1YCType yc_type();
686
687 G1HRPrinter* hr_printer() { return &_hr_printer; }
688
689 // Allocates a new heap region instance.
690 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr);
691
692 // Frees a non-humongous region by initializing its contents and
693 // adding it to the free list that's passed as a parameter (this is
694 // usually a local list which will be appended to the master free
695 // list later). The used bytes of freed regions are accumulated in
696 // pre_used. If par is true, the region's RSet will not be freed
697 // up. The assumption is that this will be done later.
698 // The locked parameter indicates if the caller has already taken
699 // care of proper synchronization. This may allow some optimizations.
700 void free_region(HeapRegion* hr,
701 FreeRegionList* free_list,
702 bool par,
703 bool locked = false);
704
705 // Frees a humongous region by collapsing it into individual regions
706 // and calling free_region() for each of them. The freed regions
707 // will be added to the free list that's passed as a parameter (this
708 // is usually a local list which will be appended to the master free
709 // list later). The used bytes of freed regions are accumulated in
710 // pre_used. If par is true, the region's RSet will not be freed
711 // up. The assumption is that this will be done later.
712 void free_humongous_region(HeapRegion* hr,
713 FreeRegionList* free_list,
714 bool par);
715 protected:
716
717 // Shrink the garbage-first heap by at most the given size (in bytes!).
718 // (Rounds down to a HeapRegion boundary.)
719 virtual void shrink(size_t expand_bytes);
720 void shrink_helper(size_t expand_bytes);
721
722 #if TASKQUEUE_STATS
723 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
724 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
725 void reset_taskqueue_stats();
726 #endif // TASKQUEUE_STATS
727
728 // Schedule the VM operation that will do an evacuation pause to
729 // satisfy an allocation request of word_size. *succeeded will
730 // return whether the VM operation was successful (it did do an
731 // evacuation pause) or not (another thread beat us to it or the GC
732 // locker was active). Given that we should not be holding the
733 // Heap_lock when we enter this method, we will pass the
734 // gc_count_before (i.e., total_collections()) as a parameter since
735 // it has to be read while holding the Heap_lock. Currently, both
736 // methods that call do_collection_pause() release the Heap_lock
737 // before the call, so it's easy to read gc_count_before just before.
738 HeapWord* do_collection_pause(size_t word_size,
739 uint gc_count_before,
740 bool* succeeded,
741 GCCause::Cause gc_cause);
742
743 // The guts of the incremental collection pause, executed by the vm
744 // thread. It returns false if it is unable to do the collection due
745 // to the GC locker being active, true otherwise
746 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
747
748 // Actually do the work of evacuating the collection set.
749 void evacuate_collection_set(EvacuationInfo& evacuation_info);
750
751 // The g1 remembered set of the heap.
752 G1RemSet* _g1_rem_set;
753
754 // A set of cards that cover the objects for which the Rsets should be updated
755 // concurrently after the collection.
756 DirtyCardQueueSet _dirty_card_queue_set;
757
758 // The closure used to refine a single card.
759 RefineCardTableEntryClosure* _refine_cte_cl;
760
761 // A DirtyCardQueueSet that is used to hold cards that contain
762 // references into the current collection set. This is used to
763 // update the remembered sets of the regions in the collection
764 // set in the event of an evacuation failure.
765 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
766
767 // After a collection pause, make the regions in the CS into free
768 // regions.
769 void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info);
770
771 // Abandon the current collection set without recording policy
772 // statistics or updating free lists.
773 void abandon_collection_set(HeapRegion* cs_head);
774
775 // Applies "scan_non_heap_roots" to roots outside the heap,
776 // "scan_rs" to roots inside the heap (having done "set_region" to
777 // indicate the region in which the root resides),
778 // and does "scan_metadata" If "scan_rs" is
779 // NULL, then this step is skipped. The "worker_i"
780 // param is for use with parallel roots processing, and should be
781 // the "i" of the calling parallel worker thread's work(i) function.
782 // In the sequential case this param will be ignored.
783 void g1_process_roots(OopClosure* scan_non_heap_roots,
784 OopClosure* scan_non_heap_weak_roots,
785 G1ParPushHeapRSClosure* scan_rs,
786 CLDClosure* scan_strong_clds,
787 CLDClosure* scan_weak_clds,
788 CodeBlobClosure* scan_strong_code,
789 uint worker_i);
790
791 // The concurrent marker (and the thread it runs in.)
792 ConcurrentMark* _cm;
793 ConcurrentMarkThread* _cmThread;
794 bool _mark_in_progress;
795
796 // The concurrent refiner.
797 ConcurrentG1Refine* _cg1r;
798
799 // The parallel task queues
800 RefToScanQueueSet *_task_queues;
801
802 // True iff a evacuation has failed in the current collection.
803 bool _evacuation_failed;
804
805 EvacuationFailedInfo* _evacuation_failed_info_array;
806
807 // Failed evacuations cause some logical from-space objects to have
808 // forwarding pointers to themselves. Reset them.
809 void remove_self_forwarding_pointers();
810
811 // Together, these store an object with a preserved mark, and its mark value.
812 Stack<oop, mtGC> _objs_with_preserved_marks;
813 Stack<markOop, mtGC> _preserved_marks_of_objs;
814
815 // Preserve the mark of "obj", if necessary, in preparation for its mark
816 // word being overwritten with a self-forwarding-pointer.
817 void preserve_mark_if_necessary(oop obj, markOop m);
818
819 // The stack of evac-failure objects left to be scanned.
820 GrowableArray<oop>* _evac_failure_scan_stack;
821 // The closure to apply to evac-failure objects.
822
823 OopsInHeapRegionClosure* _evac_failure_closure;
824 // Set the field above.
825 void
826 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
827 _evac_failure_closure = evac_failure_closure;
828 }
829
830 // Push "obj" on the scan stack.
831 void push_on_evac_failure_scan_stack(oop obj);
832 // Process scan stack entries until the stack is empty.
833 void drain_evac_failure_scan_stack();
834 // True iff an invocation of "drain_scan_stack" is in progress; to
835 // prevent unnecessary recursion.
836 bool _drain_in_progress;
837
838 // Do any necessary initialization for evacuation-failure handling.
839 // "cl" is the closure that will be used to process evac-failure
840 // objects.
841 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
842 // Do any necessary cleanup for evacuation-failure handling data
843 // structures.
844 void finalize_for_evac_failure();
845
846 // An attempt to evacuate "obj" has failed; take necessary steps.
847 oop handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, oop obj);
848 void handle_evacuation_failure_common(oop obj, markOop m);
849
850 #ifndef PRODUCT
851 // Support for forcing evacuation failures. Analogous to
852 // PromotionFailureALot for the other collectors.
853
854 // Records whether G1EvacuationFailureALot should be in effect
855 // for the current GC
856 bool _evacuation_failure_alot_for_current_gc;
857
858 // Used to record the GC number for interval checking when
859 // determining whether G1EvaucationFailureALot is in effect
860 // for the current GC.
861 size_t _evacuation_failure_alot_gc_number;
862
863 // Count of the number of evacuations between failures.
864 volatile size_t _evacuation_failure_alot_count;
865
866 // Set whether G1EvacuationFailureALot should be in effect
867 // for the current GC (based upon the type of GC and which
868 // command line flags are set);
869 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young,
870 bool during_initial_mark,
871 bool during_marking);
872
873 inline void set_evacuation_failure_alot_for_current_gc();
874
875 // Return true if it's time to cause an evacuation failure.
876 inline bool evacuation_should_fail();
877
878 // Reset the G1EvacuationFailureALot counters. Should be called at
879 // the end of an evacuation pause in which an evacuation failure occurred.
880 inline void reset_evacuation_should_fail();
881 #endif // !PRODUCT
882
883 // ("Weak") Reference processing support.
884 //
885 // G1 has 2 instances of the reference processor class. One
886 // (_ref_processor_cm) handles reference object discovery
887 // and subsequent processing during concurrent marking cycles.
888 //
889 // The other (_ref_processor_stw) handles reference object
890 // discovery and processing during full GCs and incremental
891 // evacuation pauses.
892 //
893 // During an incremental pause, reference discovery will be
894 // temporarily disabled for _ref_processor_cm and will be
895 // enabled for _ref_processor_stw. At the end of the evacuation
896 // pause references discovered by _ref_processor_stw will be
897 // processed and discovery will be disabled. The previous
898 // setting for reference object discovery for _ref_processor_cm
899 // will be re-instated.
900 //
901 // At the start of marking:
902 // * Discovery by the CM ref processor is verified to be inactive
903 // and it's discovered lists are empty.
904 // * Discovery by the CM ref processor is then enabled.
905 //
906 // At the end of marking:
907 // * Any references on the CM ref processor's discovered
908 // lists are processed (possibly MT).
909 //
910 // At the start of full GC we:
911 // * Disable discovery by the CM ref processor and
912 // empty CM ref processor's discovered lists
913 // (without processing any entries).
914 // * Verify that the STW ref processor is inactive and it's
915 // discovered lists are empty.
916 // * Temporarily set STW ref processor discovery as single threaded.
917 // * Temporarily clear the STW ref processor's _is_alive_non_header
918 // field.
919 // * Finally enable discovery by the STW ref processor.
920 //
921 // The STW ref processor is used to record any discovered
922 // references during the full GC.
923 //
924 // At the end of a full GC we:
925 // * Enqueue any reference objects discovered by the STW ref processor
926 // that have non-live referents. This has the side-effect of
927 // making the STW ref processor inactive by disabling discovery.
928 // * Verify that the CM ref processor is still inactive
929 // and no references have been placed on it's discovered
930 // lists (also checked as a precondition during initial marking).
931
932 // The (stw) reference processor...
933 ReferenceProcessor* _ref_processor_stw;
934
935 STWGCTimer* _gc_timer_stw;
936 ConcurrentGCTimer* _gc_timer_cm;
937
938 G1OldTracer* _gc_tracer_cm;
939 G1NewTracer* _gc_tracer_stw;
940
941 // During reference object discovery, the _is_alive_non_header
942 // closure (if non-null) is applied to the referent object to
943 // determine whether the referent is live. If so then the
944 // reference object does not need to be 'discovered' and can
945 // be treated as a regular oop. This has the benefit of reducing
946 // the number of 'discovered' reference objects that need to
947 // be processed.
948 //
949 // Instance of the is_alive closure for embedding into the
950 // STW reference processor as the _is_alive_non_header field.
951 // Supplying a value for the _is_alive_non_header field is
952 // optional but doing so prevents unnecessary additions to
953 // the discovered lists during reference discovery.
954 G1STWIsAliveClosure _is_alive_closure_stw;
955
956 // The (concurrent marking) reference processor...
957 ReferenceProcessor* _ref_processor_cm;
958
959 // Instance of the concurrent mark is_alive closure for embedding
960 // into the Concurrent Marking reference processor as the
961 // _is_alive_non_header field. Supplying a value for the
962 // _is_alive_non_header field is optional but doing so prevents
963 // unnecessary additions to the discovered lists during reference
964 // discovery.
965 G1CMIsAliveClosure _is_alive_closure_cm;
966
967 // Cache used by G1CollectedHeap::start_cset_region_for_worker().
968 HeapRegion** _worker_cset_start_region;
969
970 // Time stamp to validate the regions recorded in the cache
971 // used by G1CollectedHeap::start_cset_region_for_worker().
972 // The heap region entry for a given worker is valid iff
973 // the associated time stamp value matches the current value
974 // of G1CollectedHeap::_gc_time_stamp.
975 uint* _worker_cset_start_region_time_stamp;
976
977 enum G1H_process_roots_tasks {
978 G1H_PS_filter_satb_buffers,
979 G1H_PS_refProcessor_oops_do,
980 // Leave this one last.
981 G1H_PS_NumElements
982 };
983
984 SubTasksDone* _process_strong_tasks;
985
986 volatile bool _free_regions_coming;
987
988 public:
989
990 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
991
992 void set_refine_cte_cl_concurrency(bool concurrent);
993
994 RefToScanQueue *task_queue(int i) const;
995
996 // A set of cards where updates happened during the GC
997 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
998
999 // A DirtyCardQueueSet that is used to hold cards that contain
1000 // references into the current collection set. This is used to
1001 // update the remembered sets of the regions in the collection
1002 // set in the event of an evacuation failure.
1003 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
1004 { return _into_cset_dirty_card_queue_set; }
1005
1006 // Create a G1CollectedHeap with the specified policy.
1007 // Must call the initialize method afterwards.
1008 // May not return if something goes wrong.
1009 G1CollectedHeap(G1CollectorPolicy* policy);
1010
1011 // Initialize the G1CollectedHeap to have the initial and
1012 // maximum sizes and remembered and barrier sets
1013 // specified by the policy object.
1014 jint initialize();
1015
1016 virtual void stop();
1017
1018 // Return the (conservative) maximum heap alignment for any G1 heap
1019 static size_t conservative_max_heap_alignment();
1020
1021 // Initialize weak reference processing.
1022 virtual void ref_processing_init();
1023
1024 void set_par_threads(uint t) {
1025 SharedHeap::set_par_threads(t);
1026 // Done in SharedHeap but oddly there are
1027 // two _process_strong_tasks's in a G1CollectedHeap
1028 // so do it here too.
1029 _process_strong_tasks->set_n_threads(t);
1030 }
1031
1032 // Set _n_par_threads according to a policy TBD.
1033 void set_par_threads();
1034
1035 void set_n_termination(int t) {
1036 _process_strong_tasks->set_n_threads(t);
1037 }
1038
1039 virtual CollectedHeap::Name kind() const {
1040 return CollectedHeap::G1CollectedHeap;
1041 }
1042
1043 // The current policy object for the collector.
1044 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
1045
1046 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); }
1047
1048 // Adaptive size policy. No such thing for g1.
1049 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
1050
1051 // The rem set and barrier set.
1052 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
1053
1054 unsigned get_gc_time_stamp() {
1055 return _gc_time_stamp;
1056 }
1057
1058 inline void reset_gc_time_stamp();
1059
1060 void check_gc_time_stamps() PRODUCT_RETURN;
1061
1062 inline void increment_gc_time_stamp();
1063
1064 // Reset the given region's GC timestamp. If it's starts humongous,
1065 // also reset the GC timestamp of its corresponding
1066 // continues humongous regions too.
1067 void reset_gc_time_stamps(HeapRegion* hr);
1068
1069 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
1070 DirtyCardQueue* into_cset_dcq,
1071 bool concurrent, uint worker_i);
1072
1073 // The shared block offset table array.
1074 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
1075
1076 // Reference Processing accessors
1077
1078 // The STW reference processor....
1079 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1080
1081 // The Concurrent Marking reference processor...
1082 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1083
1084 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; }
1085 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; }
1086
1087 virtual size_t capacity() const;
1088 virtual size_t used() const;
1089 // This should be called when we're not holding the heap lock. The
1090 // result might be a bit inaccurate.
1091 size_t used_unlocked() const;
1092 size_t recalculate_used() const;
1093
1094 void increase_used(size_t bytes) { _summary_bytes_used += bytes; }
1095 void set_used(size_t bytes) { _summary_bytes_used = bytes; }
1096
1097 void decrease_used(size_t bytes) {
1098 assert(_summary_bytes_used >= bytes,
1099 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" should be >= bytes: "SIZE_FORMAT,
1100 _summary_bytes_used, bytes));
1101 _summary_bytes_used -= bytes;
1102 }
1103
1104 // These virtual functions do the actual allocation.
1105 // Some heaps may offer a contiguous region for shared non-blocking
1106 // allocation, via inlined code (by exporting the address of the top and
1107 // end fields defining the extent of the contiguous allocation region.)
1108 // But G1CollectedHeap doesn't yet support this.
1109
1110 virtual bool is_maximal_no_gc() const {
1111 return _hrm.available() == 0;
1112 }
1113
1114 // The current number of regions in the heap.
1115 uint num_regions() const { return _hrm.length(); }
1116
1117 // The max number of regions in the heap.
1118 uint max_regions() const { return _hrm.max_length(); }
1119
1120 // The number of regions that are completely free.
1121 uint num_free_regions() const { return _hrm.num_free_regions(); }
1122
1123 // The number of regions that are not completely free.
1124 uint num_used_regions() const { return num_regions() - num_free_regions(); }
1125
1126 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1127 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1128 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
1129 void verify_dirty_young_regions() PRODUCT_RETURN;
1130
1131 #ifndef PRODUCT
1132 // Make sure that the given bitmap has no marked objects in the
1133 // range [from,limit). If it does, print an error message and return
1134 // false. Otherwise, just return true. bitmap_name should be "prev"
1135 // or "next".
1136 bool verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
1137 HeapWord* from, HeapWord* limit);
1138
1139 // Verify that the prev / next bitmap range [tams,end) for the given
1140 // region has no marks. Return true if all is well, false if errors
1141 // are detected.
1142 bool verify_bitmaps(const char* caller, HeapRegion* hr);
1143 #endif // PRODUCT
1144
1145 // If G1VerifyBitmaps is set, verify that the marking bitmaps for
1146 // the given region do not have any spurious marks. If errors are
1147 // detected, print appropriate error messages and crash.
1148 void check_bitmaps(const char* caller, HeapRegion* hr) PRODUCT_RETURN;
1149
1150 // If G1VerifyBitmaps is set, verify that the marking bitmaps do not
1151 // have any spurious marks. If errors are detected, print
1152 // appropriate error messages and crash.
1153 void check_bitmaps(const char* caller) PRODUCT_RETURN;
1154
1155 // Do sanity check on the contents of the in-cset fast test table.
1156 bool check_cset_fast_test() PRODUCT_RETURN_( return true; );
1157
1158 // verify_region_sets() performs verification over the region
1159 // lists. It will be compiled in the product code to be used when
1160 // necessary (i.e., during heap verification).
1161 void verify_region_sets();
1162
1163 // verify_region_sets_optional() is planted in the code for
1164 // list verification in non-product builds (and it can be enabled in
1165 // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1).
1166 #if HEAP_REGION_SET_FORCE_VERIFY
1167 void verify_region_sets_optional() {
1168 verify_region_sets();
1169 }
1170 #else // HEAP_REGION_SET_FORCE_VERIFY
1171 void verify_region_sets_optional() { }
1172 #endif // HEAP_REGION_SET_FORCE_VERIFY
1173
1174 #ifdef ASSERT
1175 bool is_on_master_free_list(HeapRegion* hr) {
1176 return _hrm.is_free(hr);
1177 }
1178 #endif // ASSERT
1179
1180 // Wrapper for the region list operations that can be called from
1181 // methods outside this class.
1182
1183 void secondary_free_list_add(FreeRegionList* list) {
1184 _secondary_free_list.add_ordered(list);
1185 }
1186
1187 void append_secondary_free_list() {
1188 _hrm.insert_list_into_free_list(&_secondary_free_list);
1189 }
1190
1191 void append_secondary_free_list_if_not_empty_with_lock() {
1192 // If the secondary free list looks empty there's no reason to
1193 // take the lock and then try to append it.
1194 if (!_secondary_free_list.is_empty()) {
1195 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1196 append_secondary_free_list();
1197 }
1198 }
1199
1200 inline void old_set_remove(HeapRegion* hr);
1201
1202 size_t non_young_capacity_bytes() {
1203 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes();
1204 }
1205
1206 void set_free_regions_coming();
1207 void reset_free_regions_coming();
1208 bool free_regions_coming() { return _free_regions_coming; }
1209 void wait_while_free_regions_coming();
1210
1211 // Determine whether the given region is one that we are using as an
1212 // old GC alloc region.
1213 bool is_old_gc_alloc_region(HeapRegion* hr) {
1214 return _allocator->is_retained_old_region(hr);
1215 }
1216
1217 // Perform a collection of the heap; intended for use in implementing
1218 // "System.gc". This probably implies as full a collection as the
1219 // "CollectedHeap" supports.
1220 virtual void collect(GCCause::Cause cause);
1221
1222 // The same as above but assume that the caller holds the Heap_lock.
1223 void collect_locked(GCCause::Cause cause);
1224
1225 virtual bool copy_allocation_context_stats(const jint* contexts,
1226 jlong* totals,
1227 jbyte* accuracy,
1228 jint len);
1229
1230 // True iff an evacuation has failed in the most-recent collection.
1231 bool evacuation_failed() { return _evacuation_failed; }
1232
1233 void remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, const HeapRegionSetCount& humongous_regions_removed);
1234 void prepend_to_freelist(FreeRegionList* list);
1235 void decrement_summary_bytes(size_t bytes);
1236
1237 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1238 virtual bool is_in(const void* p) const;
1239 #ifdef ASSERT
1240 // Returns whether p is in one of the available areas of the heap. Slow but
1241 // extensive version.
1242 bool is_in_exact(const void* p) const;
1243 #endif
1244
1245 // Return "TRUE" iff the given object address is within the collection
1246 // set. Slow implementation.
1247 inline bool obj_in_cs(oop obj);
1248
1249 inline bool is_in_cset(oop obj);
1250
1251 inline bool is_in_cset_or_humongous(const oop obj);
1252
1253 private:
1254 // This array is used for a quick test on whether a reference points into
1255 // the collection set or not. Each of the array's elements denotes whether the
1256 // corresponding region is in the collection set or not.
1257 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test;
1258
1259 public:
1260
1261 inline InCSetState in_cset_state(const oop obj);
1262
1263 // Return "TRUE" iff the given object address is in the reserved
1264 // region of g1.
1265 bool is_in_g1_reserved(const void* p) const {
1266 return _hrm.reserved().contains(p);
1267 }
1268
1269 // Returns a MemRegion that corresponds to the space that has been
1270 // reserved for the heap
1271 MemRegion g1_reserved() const {
1272 return _hrm.reserved();
1273 }
1274
1275 virtual bool is_in_closed_subset(const void* p) const;
1276
1277 G1SATBCardTableLoggingModRefBS* g1_barrier_set() {
1278 return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set());
1279 }
1280
1281 // This resets the card table to all zeros. It is used after
1282 // a collection pause which used the card table to claim cards.
1283 void cleanUpCardTable();
1284
1285 // Iteration functions.
1286
1287 // Iterate over all the ref-containing fields of all objects, calling
1288 // "cl.do_oop" on each.
1289 virtual void oop_iterate(ExtendedOopClosure* cl);
1290
1291 // Iterate over all objects, calling "cl.do_object" on each.
1292 virtual void object_iterate(ObjectClosure* cl);
1293
1294 virtual void safe_object_iterate(ObjectClosure* cl) {
1295 object_iterate(cl);
1296 }
1297
1298 // Iterate over all spaces in use in the heap, in ascending address order.
1299 virtual void space_iterate(SpaceClosure* cl);
1300
1301 // Iterate over heap regions, in address order, terminating the
1302 // iteration early if the "doHeapRegion" method returns "true".
1303 void heap_region_iterate(HeapRegionClosure* blk) const;
1304
1305 // Return the region with the given index. It assumes the index is valid.
1306 inline HeapRegion* region_at(uint index) const;
1307
1308 // Calculate the region index of the given address. Given address must be
1309 // within the heap.
1310 inline uint addr_to_region(HeapWord* addr) const;
1311
1312 inline HeapWord* bottom_addr_for_region(uint index) const;
1313
1314 // Iterate over the heap regions in parallel. Assumes that this will be called
1315 // in parallel by ParallelGCThreads worker threads with distinct worker ids
1316 // in the range [0..max(ParallelGCThreads-1, 1)]. Applies "blk->doHeapRegion"
1317 // to each of the regions, by attempting to claim the region using the
1318 // HeapRegionClaimer and, if successful, applying the closure to the claimed
1319 // region. The concurrent argument should be set to true if iteration is
1320 // performed concurrently, during which no assumptions are made for consistent
1321 // attributes of the heap regions (as they might be modified while iterating).
1322 void heap_region_par_iterate(HeapRegionClosure* cl,
1323 uint worker_id,
1324 HeapRegionClaimer* hrclaimer,
1325 bool concurrent = false) const;
1326
1327 // Clear the cached cset start regions and (more importantly)
1328 // the time stamps. Called when we reset the GC time stamp.
1329 void clear_cset_start_regions();
1330
1331 // Given the id of a worker, obtain or calculate a suitable
1332 // starting region for iterating over the current collection set.
1333 HeapRegion* start_cset_region_for_worker(uint worker_i);
1334
1335 // Iterate over the regions (if any) in the current collection set.
1336 void collection_set_iterate(HeapRegionClosure* blk);
1337
1338 // As above but starting from region r
1339 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1340
1341 HeapRegion* next_compaction_region(const HeapRegion* from) const;
1342
1343 // A CollectedHeap will contain some number of spaces. This finds the
1344 // space containing a given address, or else returns NULL.
1345 virtual Space* space_containing(const void* addr) const;
1346
1347 // Returns the HeapRegion that contains addr. addr must not be NULL.
1348 template <class T>
1349 inline HeapRegion* heap_region_containing_raw(const T addr) const;
1350
1351 // Returns the HeapRegion that contains addr. addr must not be NULL.
1352 // If addr is within a humongous continues region, it returns its humongous start region.
1353 template <class T>
1354 inline HeapRegion* heap_region_containing(const T addr) const;
1355
1356 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1357 // each address in the (reserved) heap is a member of exactly
1358 // one block. The defining characteristic of a block is that it is
1359 // possible to find its size, and thus to progress forward to the next
1360 // block. (Blocks may be of different sizes.) Thus, blocks may
1361 // represent Java objects, or they might be free blocks in a
1362 // free-list-based heap (or subheap), as long as the two kinds are
1363 // distinguishable and the size of each is determinable.
1364
1365 // Returns the address of the start of the "block" that contains the
1366 // address "addr". We say "blocks" instead of "object" since some heaps
1367 // may not pack objects densely; a chunk may either be an object or a
1368 // non-object.
1369 virtual HeapWord* block_start(const void* addr) const;
1370
1371 // Requires "addr" to be the start of a chunk, and returns its size.
1372 // "addr + size" is required to be the start of a new chunk, or the end
1373 // of the active area of the heap.
1374 virtual size_t block_size(const HeapWord* addr) const;
1375
1376 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1377 // the block is an object.
1378 virtual bool block_is_obj(const HeapWord* addr) const;
1379
1380 // Does this heap support heap inspection? (+PrintClassHistogram)
1381 virtual bool supports_heap_inspection() const { return true; }
1382
1383 // Section on thread-local allocation buffers (TLABs)
1384 // See CollectedHeap for semantics.
1385
1386 bool supports_tlab_allocation() const;
1387 size_t tlab_capacity(Thread* ignored) const;
1388 size_t tlab_used(Thread* ignored) const;
1389 size_t max_tlab_size() const;
1390 size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1391
1392 // Can a compiler initialize a new object without store barriers?
1393 // This permission only extends from the creation of a new object
1394 // via a TLAB up to the first subsequent safepoint. If such permission
1395 // is granted for this heap type, the compiler promises to call
1396 // defer_store_barrier() below on any slow path allocation of
1397 // a new object for which such initializing store barriers will
1398 // have been elided. G1, like CMS, allows this, but should be
1399 // ready to provide a compensating write barrier as necessary
1400 // if that storage came out of a non-young region. The efficiency
1401 // of this implementation depends crucially on being able to
1402 // answer very efficiently in constant time whether a piece of
1403 // storage in the heap comes from a young region or not.
1404 // See ReduceInitialCardMarks.
1405 virtual bool can_elide_tlab_store_barriers() const {
1406 return true;
1407 }
1408
1409 virtual bool card_mark_must_follow_store() const {
1410 return true;
1411 }
1412
1413 inline bool is_in_young(const oop obj);
1414
1415 #ifdef ASSERT
1416 virtual bool is_in_partial_collection(const void* p);
1417 #endif
1418
1419 virtual bool is_scavengable(const void* addr);
1420
1421 // We don't need barriers for initializing stores to objects
1422 // in the young gen: for the SATB pre-barrier, there is no
1423 // pre-value that needs to be remembered; for the remembered-set
1424 // update logging post-barrier, we don't maintain remembered set
1425 // information for young gen objects.
1426 virtual inline bool can_elide_initializing_store_barrier(oop new_obj);
1427
1428 // Returns "true" iff the given word_size is "very large".
1429 static bool is_humongous(size_t word_size) {
1430 // Note this has to be strictly greater-than as the TLABs
1431 // are capped at the humongous threshold and we want to
1432 // ensure that we don't try to allocate a TLAB as
1433 // humongous and that we don't allocate a humongous
1434 // object in a TLAB.
1435 return word_size > _humongous_object_threshold_in_words;
1436 }
1437
1438 // Update mod union table with the set of dirty cards.
1439 void updateModUnion();
1440
1441 // Set the mod union bits corresponding to the given memRegion. Note
1442 // that this is always a safe operation, since it doesn't clear any
1443 // bits.
1444 void markModUnionRange(MemRegion mr);
1445
1446 // Records the fact that a marking phase is no longer in progress.
1447 void set_marking_complete() {
1448 _mark_in_progress = false;
1449 }
1450 void set_marking_started() {
1451 _mark_in_progress = true;
1452 }
1453 bool mark_in_progress() {
1454 return _mark_in_progress;
1455 }
1456
1457 // Print the maximum heap capacity.
1458 virtual size_t max_capacity() const;
1459
1460 virtual jlong millis_since_last_gc();
1461
1462
1463 // Convenience function to be used in situations where the heap type can be
1464 // asserted to be this type.
1465 static G1CollectedHeap* heap();
1466
1467 void set_region_short_lived_locked(HeapRegion* hr);
1468 // add appropriate methods for any other surv rate groups
1469
1470 YoungList* young_list() const { return _young_list; }
1471
1472 // debugging
1473 bool check_young_list_well_formed() {
1474 return _young_list->check_list_well_formed();
1475 }
1476
1477 bool check_young_list_empty(bool check_heap,
1478 bool check_sample = true);
1479
1480 // *** Stuff related to concurrent marking. It's not clear to me that so
1481 // many of these need to be public.
1482
1483 // The functions below are helper functions that a subclass of
1484 // "CollectedHeap" can use in the implementation of its virtual
1485 // functions.
1486 // This performs a concurrent marking of the live objects in a
1487 // bitmap off to the side.
1488 void doConcurrentMark();
1489
1490 bool isMarkedPrev(oop obj) const;
1491 bool isMarkedNext(oop obj) const;
1492
1493 // Determine if an object is dead, given the object and also
1494 // the region to which the object belongs. An object is dead
1495 // iff a) it was not allocated since the last mark and b) it
1496 // is not marked.
1497 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1498 return
1499 !hr->obj_allocated_since_prev_marking(obj) &&
1500 !isMarkedPrev(obj);
1501 }
1502
1503 // This function returns true when an object has been
1504 // around since the previous marking and hasn't yet
1505 // been marked during this marking.
1506 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1507 return
1508 !hr->obj_allocated_since_next_marking(obj) &&
1509 !isMarkedNext(obj);
1510 }
1511
1512 // Determine if an object is dead, given only the object itself.
1513 // This will find the region to which the object belongs and
1514 // then call the region version of the same function.
1515
1516 // Added if it is NULL it isn't dead.
1517
1518 inline bool is_obj_dead(const oop obj) const;
1519
1520 inline bool is_obj_ill(const oop obj) const;
1521
1522 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo);
1523 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo);
1524 bool is_marked(oop obj, VerifyOption vo);
1525 const char* top_at_mark_start_str(VerifyOption vo);
1526
1527 ConcurrentMark* concurrent_mark() const { return _cm; }
1528
1529 // Refinement
1530
1531 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1532
1533 // The dirty cards region list is used to record a subset of regions
1534 // whose cards need clearing. The list if populated during the
1535 // remembered set scanning and drained during the card table
1536 // cleanup. Although the methods are reentrant, population/draining
1537 // phases must not overlap. For synchronization purposes the last
1538 // element on the list points to itself.
1539 HeapRegion* _dirty_cards_region_list;
1540 void push_dirty_cards_region(HeapRegion* hr);
1541 HeapRegion* pop_dirty_cards_region();
1542
1543 // Optimized nmethod scanning support routines
1544
1545 // Register the given nmethod with the G1 heap.
1546 virtual void register_nmethod(nmethod* nm);
1547
1548 // Unregister the given nmethod from the G1 heap.
1549 virtual void unregister_nmethod(nmethod* nm);
1550
1551 // Free up superfluous code root memory.
1552 void purge_code_root_memory();
1553
1554 // Rebuild the strong code root lists for each region
1555 // after a full GC.
1556 void rebuild_strong_code_roots();
1557
1558 // Delete entries for dead interned string and clean up unreferenced symbols
1559 // in symbol table, possibly in parallel.
1560 void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true);
1561
1562 // Parallel phase of unloading/cleaning after G1 concurrent mark.
1563 void parallel_cleaning(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool class_unloading_occurred);
1564
1565 // Redirty logged cards in the refinement queue.
1566 void redirty_logged_cards();
1567 // Verification
1568
1569 // The following is just to alert the verification code
1570 // that a full collection has occurred and that the
1571 // remembered sets are no longer up to date.
1572 bool _full_collection;
1573 void set_full_collection() { _full_collection = true;}
1574 void clear_full_collection() {_full_collection = false;}
1575 bool full_collection() {return _full_collection;}
1576
1577 // Perform any cleanup actions necessary before allowing a verification.
1578 virtual void prepare_for_verify();
1579
1580 // Perform verification.
1581
1582 // vo == UsePrevMarking -> use "prev" marking information,
1583 // vo == UseNextMarking -> use "next" marking information
1584 // vo == UseMarkWord -> use the mark word in the object header
1585 //
1586 // NOTE: Only the "prev" marking information is guaranteed to be
1587 // consistent most of the time, so most calls to this should use
1588 // vo == UsePrevMarking.
1589 // Currently, there is only one case where this is called with
1590 // vo == UseNextMarking, which is to verify the "next" marking
1591 // information at the end of remark.
1592 // Currently there is only one place where this is called with
1593 // vo == UseMarkWord, which is to verify the marking during a
1594 // full GC.
1595 void verify(bool silent, VerifyOption vo);
1596
1597 // Override; it uses the "prev" marking information
1598 virtual void verify(bool silent);
1599
1600 // The methods below are here for convenience and dispatch the
1601 // appropriate method depending on value of the given VerifyOption
1602 // parameter. The values for that parameter, and their meanings,
1603 // are the same as those above.
1604
1605 bool is_obj_dead_cond(const oop obj,
1606 const HeapRegion* hr,
1607 const VerifyOption vo) const;
1608
1609 bool is_obj_dead_cond(const oop obj,
1610 const VerifyOption vo) const;
1611
1612 // Printing
1613
1614 virtual void print_on(outputStream* st) const;
1615 virtual void print_extended_on(outputStream* st) const;
1616 virtual void print_on_error(outputStream* st) const;
1617
1618 virtual void print_gc_threads_on(outputStream* st) const;
1619 virtual void gc_threads_do(ThreadClosure* tc) const;
1620
1621 // Override
1622 void print_tracing_info() const;
1623
1624 // The following two methods are helpful for debugging RSet issues.
1625 void print_cset_rsets() PRODUCT_RETURN;
1626 void print_all_rsets() PRODUCT_RETURN;
1627
1628 public:
1629 size_t pending_card_num();
1630 size_t cards_scanned();
1631
1632 protected:
1633 size_t _max_heap_capacity;
1634 };
1635
1636 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP