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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7 * published by the Free Software Foundation.
8 *
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
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23 */
24
25 #ifndef SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP
26 #define SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP
27
28 #include "gc/g1/concurrentMark.hpp"
29 #include "gc/g1/evacuationInfo.hpp"
30 #include "gc/g1/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
190 // Closures used in implementation.
191 friend class G1ParScanThreadState;
192 friend class G1ParTask;
193 friend class G1PLABAllocator;
194 friend class G1PrepareCompactClosure;
195
196 // Other related classes.
197 friend class HeapRegionClaimer;
198
199 // Testing classes.
200 friend class G1CheckCSetFastTableClosure;
201
202 private:
203 FlexibleWorkGang* _workers;
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 eagerly_reclaim_humongous_regions();
219
220 // The number of regions we could create by expansion.
221 uint _expansion_regions;
222
223 // The block offset table for the G1 heap.
224 G1BlockOffsetSharedArray* _bot_shared;
225
226 // Tears down the region sets / lists so that they are empty and the
227 // regions on the heap do not belong to a region set / list. The
228 // only exception is the humongous set which we leave unaltered. If
229 // free_list_only is true, it will only tear down the master free
230 // list. It is called before a Full GC (free_list_only == false) or
231 // before heap shrinking (free_list_only == true).
232 void tear_down_region_sets(bool free_list_only);
233
234 // Rebuilds the region sets / lists so that they are repopulated to
235 // reflect the contents of the heap. The only exception is the
236 // humongous set which was not torn down in the first place. If
237 // free_list_only is true, it will only rebuild the master free
238 // list. It is called after a Full GC (free_list_only == false) or
239 // after heap shrinking (free_list_only == true).
240 void rebuild_region_sets(bool free_list_only);
241
242 // Callback for region mapping changed events.
243 G1RegionMappingChangedListener _listener;
244
245 // The sequence of all heap regions in the heap.
246 HeapRegionManager _hrm;
247
248 // Handles non-humongous allocations in the G1CollectedHeap.
249 G1Allocator* _allocator;
250
251 // Outside of GC pauses, the number of bytes used in all regions other
252 // than the current allocation region(s).
253 size_t _summary_bytes_used;
254
255 void increase_used(size_t bytes);
256 void decrease_used(size_t bytes);
257
258 void set_used(size_t bytes);
259
260 // Class that handles archive allocation ranges.
261 G1ArchiveAllocator* _archive_allocator;
262
263 // Statistics for each allocation context
264 AllocationContextStats _allocation_context_stats;
265
266 // PLAB sizing policy for survivors.
267 PLABStats _survivor_plab_stats;
268
269 // PLAB sizing policy for tenured objects.
270 PLABStats _old_plab_stats;
271
272 // It specifies whether we should attempt to expand the heap after a
273 // region allocation failure. If heap expansion fails we set this to
274 // false so that we don't re-attempt the heap expansion (it's likely
275 // that subsequent expansion attempts will also fail if one fails).
276 // Currently, it is only consulted during GC and it's reset at the
277 // start of each GC.
278 bool _expand_heap_after_alloc_failure;
279
280 // Helper for monitoring and management support.
281 G1MonitoringSupport* _g1mm;
282
283 // Records whether the region at the given index is (still) a
284 // candidate for eager reclaim. Only valid for humongous start
285 // regions; other regions have unspecified values. Humongous start
286 // regions are initialized at start of collection pause, with
287 // candidates removed from the set as they are found reachable from
288 // roots or the young generation.
289 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> {
290 protected:
291 bool default_value() const { return false; }
292 public:
293 void clear() { G1BiasedMappedArray<bool>::clear(); }
294 void set_candidate(uint region, bool value) {
295 set_by_index(region, value);
296 }
297 bool is_candidate(uint region) {
298 return get_by_index(region);
299 }
300 };
301
302 HumongousReclaimCandidates _humongous_reclaim_candidates;
303 // Stores whether during humongous object registration we found candidate regions.
304 // If not, we can skip a few steps.
305 bool _has_humongous_reclaim_candidates;
306
307 volatile unsigned _gc_time_stamp;
308
309 size_t* _surviving_young_words;
310
311 G1HRPrinter _hr_printer;
312
313 void setup_surviving_young_words();
314 void update_surviving_young_words(size_t* surv_young_words);
315 void cleanup_surviving_young_words();
316
317 // It decides whether an explicit GC should start a concurrent cycle
318 // instead of doing a STW GC. Currently, a concurrent cycle is
319 // explicitly started if:
320 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
321 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
322 // (c) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent.
323 // (d) cause == _g1_humongous_allocation
324 bool should_do_concurrent_full_gc(GCCause::Cause cause);
325
326 // indicates whether we are in young or mixed GC mode
327 G1CollectorState _collector_state;
328
329 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
330 // concurrent cycles) we have started.
331 volatile uint _old_marking_cycles_started;
332
333 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
334 // concurrent cycles) we have completed.
335 volatile uint _old_marking_cycles_completed;
336
337 bool _heap_summary_sent;
338
339 // This is a non-product method that is helpful for testing. It is
340 // called at the end of a GC and artificially expands the heap by
341 // allocating a number of dead regions. This way we can induce very
342 // frequent marking cycles and stress the cleanup / concurrent
343 // cleanup code more (as all the regions that will be allocated by
344 // this method will be found dead by the marking cycle).
345 void allocate_dummy_regions() PRODUCT_RETURN;
346
347 // Clear RSets after a compaction. It also resets the GC time stamps.
348 void clear_rsets_post_compaction();
349
350 // If the HR printer is active, dump the state of the regions in the
351 // heap after a compaction.
352 void print_hrm_post_compaction();
353
354 // Create a memory mapper for auxiliary data structures of the given size and
355 // translation factor.
356 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description,
357 size_t size,
358 size_t translation_factor);
359
360 double verify(bool guard, const char* msg);
361 void verify_before_gc();
362 void verify_after_gc();
363
364 void log_gc_header();
365 void log_gc_footer(double pause_time_sec);
366
367 void trace_heap(GCWhen::Type when, const GCTracer* tracer);
368
369 // These are macros so that, if the assert fires, we get the correct
370 // line number, file, etc.
371
372 #define heap_locking_asserts_err_msg(_extra_message_) \
373 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
374 (_extra_message_), \
375 BOOL_TO_STR(Heap_lock->owned_by_self()), \
376 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
377 BOOL_TO_STR(Thread::current()->is_VM_thread()))
378
379 #define assert_heap_locked() \
380 do { \
381 assert(Heap_lock->owned_by_self(), \
382 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
383 } while (0)
384
385 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
386 do { \
387 assert(Heap_lock->owned_by_self() || \
388 (SafepointSynchronize::is_at_safepoint() && \
389 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
390 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
391 "should be at a safepoint")); \
392 } while (0)
393
394 #define assert_heap_locked_and_not_at_safepoint() \
395 do { \
396 assert(Heap_lock->owned_by_self() && \
397 !SafepointSynchronize::is_at_safepoint(), \
398 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
399 "should not be at a safepoint")); \
400 } while (0)
401
402 #define assert_heap_not_locked() \
403 do { \
404 assert(!Heap_lock->owned_by_self(), \
405 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
406 } while (0)
407
408 #define assert_heap_not_locked_and_not_at_safepoint() \
409 do { \
410 assert(!Heap_lock->owned_by_self() && \
411 !SafepointSynchronize::is_at_safepoint(), \
412 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
413 "should not be at a safepoint")); \
414 } while (0)
415
416 #define assert_at_safepoint(_should_be_vm_thread_) \
417 do { \
418 assert(SafepointSynchronize::is_at_safepoint() && \
419 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
420 heap_locking_asserts_err_msg("should be at a safepoint")); \
421 } while (0)
422
423 #define assert_not_at_safepoint() \
424 do { \
425 assert(!SafepointSynchronize::is_at_safepoint(), \
426 heap_locking_asserts_err_msg("should not be at a safepoint")); \
427 } while (0)
428
429 protected:
430
431 // The young region list.
432 YoungList* _young_list;
433
434 // The current policy object for the collector.
435 G1CollectorPolicy* _g1_policy;
436
437 // This is the second level of trying to allocate a new region. If
438 // new_region() didn't find a region on the free_list, this call will
439 // check whether there's anything available on the
440 // secondary_free_list and/or wait for more regions to appear on
441 // that list, if _free_regions_coming is set.
442 HeapRegion* new_region_try_secondary_free_list(bool is_old);
443
444 // Try to allocate a single non-humongous HeapRegion sufficient for
445 // an allocation of the given word_size. If do_expand is true,
446 // attempt to expand the heap if necessary to satisfy the allocation
447 // request. If the region is to be used as an old region or for a
448 // humongous object, set is_old to true. If not, to false.
449 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand);
450
451 // Initialize a contiguous set of free regions of length num_regions
452 // and starting at index first so that they appear as a single
453 // humongous region.
454 HeapWord* humongous_obj_allocate_initialize_regions(uint first,
455 uint num_regions,
456 size_t word_size,
457 AllocationContext_t context);
458
459 // Attempt to allocate a humongous object of the given size. Return
460 // NULL if unsuccessful.
461 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context);
462
463 // The following two methods, allocate_new_tlab() and
464 // mem_allocate(), are the two main entry points from the runtime
465 // into the G1's allocation routines. They have the following
466 // assumptions:
467 //
468 // * They should both be called outside safepoints.
469 //
470 // * They should both be called without holding the Heap_lock.
471 //
472 // * All allocation requests for new TLABs should go to
473 // allocate_new_tlab().
474 //
475 // * All non-TLAB allocation requests should go to mem_allocate().
476 //
477 // * If either call cannot satisfy the allocation request using the
478 // current allocating region, they will try to get a new one. If
479 // this fails, they will attempt to do an evacuation pause and
480 // retry the allocation.
481 //
482 // * If all allocation attempts fail, even after trying to schedule
483 // an evacuation pause, allocate_new_tlab() will return NULL,
484 // whereas mem_allocate() will attempt a heap expansion and/or
485 // schedule a Full GC.
486 //
487 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
488 // should never be called with word_size being humongous. All
489 // humongous allocation requests should go to mem_allocate() which
490 // will satisfy them with a special path.
491
492 virtual HeapWord* allocate_new_tlab(size_t word_size);
493
494 virtual HeapWord* mem_allocate(size_t word_size,
495 bool* gc_overhead_limit_was_exceeded);
496
497 // The following three methods take a gc_count_before_ret
498 // parameter which is used to return the GC count if the method
499 // returns NULL. Given that we are required to read the GC count
500 // while holding the Heap_lock, and these paths will take the
501 // Heap_lock at some point, it's easier to get them to read the GC
502 // count while holding the Heap_lock before they return NULL instead
503 // of the caller (namely: mem_allocate()) having to also take the
504 // Heap_lock just to read the GC count.
505
506 // First-level mutator allocation attempt: try to allocate out of
507 // the mutator alloc region without taking the Heap_lock. This
508 // should only be used for non-humongous allocations.
509 inline HeapWord* attempt_allocation(size_t word_size,
510 uint* gc_count_before_ret,
511 uint* gclocker_retry_count_ret);
512
513 // Second-level mutator allocation attempt: take the Heap_lock and
514 // retry the allocation attempt, potentially scheduling a GC
515 // pause. This should only be used for non-humongous allocations.
516 HeapWord* attempt_allocation_slow(size_t word_size,
517 AllocationContext_t context,
518 uint* gc_count_before_ret,
519 uint* gclocker_retry_count_ret);
520
521 // Takes the Heap_lock and attempts a humongous allocation. It can
522 // potentially schedule a GC pause.
523 HeapWord* attempt_allocation_humongous(size_t word_size,
524 uint* gc_count_before_ret,
525 uint* gclocker_retry_count_ret);
526
527 // Allocation attempt that should be called during safepoints (e.g.,
528 // at the end of a successful GC). expect_null_mutator_alloc_region
529 // specifies whether the mutator alloc region is expected to be NULL
530 // or not.
531 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
532 AllocationContext_t context,
533 bool expect_null_mutator_alloc_region);
534
535 // These methods are the "callbacks" from the G1AllocRegion class.
536
537 // For mutator alloc regions.
538 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
539 void retire_mutator_alloc_region(HeapRegion* alloc_region,
540 size_t allocated_bytes);
541
542 // For GC alloc regions.
543 HeapRegion* new_gc_alloc_region(size_t word_size, uint count,
544 InCSetState dest);
545 void retire_gc_alloc_region(HeapRegion* alloc_region,
546 size_t allocated_bytes, InCSetState dest);
547
548 // - if explicit_gc is true, the GC is for a System.gc() or a heap
549 // inspection request and should collect the entire heap
550 // - if clear_all_soft_refs is true, all soft references should be
551 // cleared during the GC
552 // - if explicit_gc is false, word_size describes the allocation that
553 // the GC should attempt (at least) to satisfy
554 // - it returns false if it is unable to do the collection due to the
555 // GC locker being active, true otherwise
556 bool do_collection(bool explicit_gc,
557 bool clear_all_soft_refs,
558 size_t word_size);
559
560 // Callback from VM_G1CollectFull operation.
561 // Perform a full collection.
562 virtual void do_full_collection(bool clear_all_soft_refs);
563
564 // Resize the heap if necessary after a full collection. If this is
565 // after a collect-for allocation, "word_size" is the allocation size,
566 // and will be considered part of the used portion of the heap.
567 void resize_if_necessary_after_full_collection(size_t word_size);
568
569 // Callback from VM_G1CollectForAllocation operation.
570 // This function does everything necessary/possible to satisfy a
571 // failed allocation request (including collection, expansion, etc.)
572 HeapWord* satisfy_failed_allocation(size_t word_size,
573 AllocationContext_t context,
574 bool* succeeded);
575
576 // Attempting to expand the heap sufficiently
577 // to support an allocation of the given "word_size". If
578 // successful, perform the allocation and return the address of the
579 // allocated block, or else "NULL".
580 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context);
581
582 // Process any reference objects discovered during
583 // an incremental evacuation pause.
584 void process_discovered_references();
585
586 // Enqueue any remaining discovered references
587 // after processing.
588 void enqueue_discovered_references();
589
590 public:
591 FlexibleWorkGang* workers() const { return _workers; }
592
593 G1Allocator* allocator() {
594 return _allocator;
595 }
596
597 G1MonitoringSupport* g1mm() {
598 assert(_g1mm != NULL, "should have been initialized");
599 return _g1mm;
600 }
601
602 // Expand the garbage-first heap by at least the given size (in bytes!).
603 // Returns true if the heap was expanded by the requested amount;
604 // false otherwise.
605 // (Rounds up to a HeapRegion boundary.)
606 bool expand(size_t expand_bytes);
607
608 // Returns the PLAB statistics for a given destination.
609 inline PLABStats* alloc_buffer_stats(InCSetState dest);
610
611 // Determines PLAB size for a given destination.
612 inline size_t desired_plab_sz(InCSetState dest);
613
614 inline AllocationContextStats& allocation_context_stats();
615
616 // Do anything common to GC's.
617 void gc_prologue(bool full);
618 void gc_epilogue(bool full);
619
620 // Modify the reclaim candidate set and test for presence.
621 // These are only valid for starts_humongous regions.
622 inline void set_humongous_reclaim_candidate(uint region, bool value);
623 inline bool is_humongous_reclaim_candidate(uint region);
624
625 // Remove from the reclaim candidate set. Also remove from the
626 // collection set so that later encounters avoid the slow path.
627 inline void set_humongous_is_live(oop obj);
628
629 // Register the given region to be part of the collection set.
630 inline void register_humongous_region_with_cset(uint index);
631 // Register regions with humongous objects (actually on the start region) in
632 // the in_cset_fast_test table.
633 void register_humongous_regions_with_cset();
634 // We register a region with the fast "in collection set" test. We
635 // simply set to true the array slot corresponding to this region.
636 void register_young_region_with_cset(HeapRegion* r) {
637 _in_cset_fast_test.set_in_young(r->hrm_index());
638 }
639 void register_old_region_with_cset(HeapRegion* r) {
640 _in_cset_fast_test.set_in_old(r->hrm_index());
641 }
642 void clear_in_cset(const HeapRegion* hr) {
643 _in_cset_fast_test.clear(hr);
644 }
645
646 void clear_cset_fast_test() {
647 _in_cset_fast_test.clear();
648 }
649
650 // This is called at the start of either a concurrent cycle or a Full
651 // GC to update the number of old marking cycles started.
652 void increment_old_marking_cycles_started();
653
654 // This is called at the end of either a concurrent cycle or a Full
655 // GC to update the number of old marking cycles completed. Those two
656 // can happen in a nested fashion, i.e., we start a concurrent
657 // cycle, a Full GC happens half-way through it which ends first,
658 // and then the cycle notices that a Full GC happened and ends
659 // too. The concurrent parameter is a boolean to help us do a bit
660 // tighter consistency checking in the method. If concurrent is
661 // false, the caller is the inner caller in the nesting (i.e., the
662 // Full GC). If concurrent is true, the caller is the outer caller
663 // in this nesting (i.e., the concurrent cycle). Further nesting is
664 // not currently supported. The end of this call also notifies
665 // the FullGCCount_lock in case a Java thread is waiting for a full
666 // GC to happen (e.g., it called System.gc() with
667 // +ExplicitGCInvokesConcurrent).
668 void increment_old_marking_cycles_completed(bool concurrent);
669
670 uint old_marking_cycles_completed() {
671 return _old_marking_cycles_completed;
672 }
673
674 void register_concurrent_cycle_start(const Ticks& start_time);
675 void register_concurrent_cycle_end();
676 void trace_heap_after_concurrent_cycle();
677
678 G1HRPrinter* hr_printer() { return &_hr_printer; }
679
680 // Allocates a new heap region instance.
681 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr);
682
683 // Allocate the highest free region in the reserved heap. This will commit
684 // regions as necessary.
685 HeapRegion* alloc_highest_free_region();
686
687 // Frees a non-humongous region by initializing its contents and
688 // adding it to the free list that's passed as a parameter (this is
689 // usually a local list which will be appended to the master free
690 // list later). The used bytes of freed regions are accumulated in
691 // pre_used. If par is true, the region's RSet will not be freed
692 // up. The assumption is that this will be done later.
693 // The locked parameter indicates if the caller has already taken
694 // care of proper synchronization. This may allow some optimizations.
695 void free_region(HeapRegion* hr,
696 FreeRegionList* free_list,
697 bool par,
698 bool locked = false);
699
700 // It dirties the cards that cover the block so that the post
701 // write barrier never queues anything when updating objects on this
702 // block. It is assumed (and in fact we assert) that the block
703 // belongs to a young region.
704 inline void dirty_young_block(HeapWord* start, size_t word_size);
705
706 // Frees a humongous region by collapsing it into individual regions
707 // and calling free_region() for each of them. The freed regions
708 // will be added to the free list that's passed as a parameter (this
709 // is usually a local list which will be appended to the master free
710 // list later). The used bytes of freed regions are accumulated in
711 // pre_used. If par is true, the region's RSet will not be freed
712 // up. The assumption is that this will be done later.
713 void free_humongous_region(HeapRegion* hr,
714 FreeRegionList* free_list,
715 bool par);
716
717 // Facility for allocating in 'archive' regions in high heap memory and
718 // recording the allocated ranges. These should all be called from the
719 // VM thread at safepoints, without the heap lock held. They can be used
720 // to create and archive a set of heap regions which can be mapped at the
721 // same fixed addresses in a subsequent JVM invocation.
722 void begin_archive_alloc_range();
723
724 // Check if the requested size would be too large for an archive allocation.
725 bool is_archive_alloc_too_large(size_t word_size);
726
727 // Allocate memory of the requested size from the archive region. This will
728 // return NULL if the size is too large or if no memory is available. It
729 // does not trigger a garbage collection.
730 HeapWord* archive_mem_allocate(size_t word_size);
731
732 // Optionally aligns the end address and returns the allocated ranges in
733 // an array of MemRegions in order of ascending addresses.
734 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
735 size_t end_alignment_in_bytes = 0);
736
737 // Facility for allocating a fixed range within the heap and marking
738 // the containing regions as 'archive'. For use at JVM init time, when the
739 // caller may mmap archived heap data at the specified range(s).
740 // Verify that the MemRegions specified in the argument array are within the
741 // reserved heap.
742 bool check_archive_addresses(MemRegion* range, size_t count);
743
744 // Commit the appropriate G1 regions containing the specified MemRegions
745 // and mark them as 'archive' regions. The regions in the array must be
746 // non-overlapping and in order of ascending address.
747 bool alloc_archive_regions(MemRegion* range, size_t count);
748
749 // Insert any required filler objects in the G1 regions around the specified
750 // ranges to make the regions parseable. This must be called after
751 // alloc_archive_regions, and after class loading has occurred.
752 void fill_archive_regions(MemRegion* range, size_t count);
753
754 // For each of the specified MemRegions, free the containing G1 regions
755 // which had been allocated by alloc_archive_regions. This should be called
756 // rather than fill_archive_regions at JVM init time if the archive file
757 // mapping failed, with the same non-overlapping and sorted MemRegion array.
758 void free_archive_regions(MemRegion* range, size_t count);
759
760 protected:
761
762 // Shrink the garbage-first heap by at most the given size (in bytes!).
763 // (Rounds down to a HeapRegion boundary.)
764 virtual void shrink(size_t expand_bytes);
765 void shrink_helper(size_t expand_bytes);
766
767 #if TASKQUEUE_STATS
768 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
769 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
770 void reset_taskqueue_stats();
771 #endif // TASKQUEUE_STATS
772
773 // Schedule the VM operation that will do an evacuation pause to
774 // satisfy an allocation request of word_size. *succeeded will
775 // return whether the VM operation was successful (it did do an
776 // evacuation pause) or not (another thread beat us to it or the GC
777 // locker was active). Given that we should not be holding the
778 // Heap_lock when we enter this method, we will pass the
779 // gc_count_before (i.e., total_collections()) as a parameter since
780 // it has to be read while holding the Heap_lock. Currently, both
781 // methods that call do_collection_pause() release the Heap_lock
782 // before the call, so it's easy to read gc_count_before just before.
783 HeapWord* do_collection_pause(size_t word_size,
784 uint gc_count_before,
785 bool* succeeded,
786 GCCause::Cause gc_cause);
787
788 void wait_for_root_region_scanning();
789
790 // The guts of the incremental collection pause, executed by the vm
791 // thread. It returns false if it is unable to do the collection due
792 // to the GC locker being active, true otherwise
793 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
794
795 // Actually do the work of evacuating the collection set.
796 void evacuate_collection_set(EvacuationInfo& evacuation_info);
797
798 // The g1 remembered set of the heap.
799 G1RemSet* _g1_rem_set;
800
801 // A set of cards that cover the objects for which the Rsets should be updated
802 // concurrently after the collection.
803 DirtyCardQueueSet _dirty_card_queue_set;
804
805 // The closure used to refine a single card.
806 RefineCardTableEntryClosure* _refine_cte_cl;
807
808 // A DirtyCardQueueSet that is used to hold cards that contain
809 // references into the current collection set. This is used to
810 // update the remembered sets of the regions in the collection
811 // set in the event of an evacuation failure.
812 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
813
814 // After a collection pause, make the regions in the CS into free
815 // regions.
816 void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info);
817
818 // Abandon the current collection set without recording policy
819 // statistics or updating free lists.
820 void abandon_collection_set(HeapRegion* cs_head);
821
822 // The concurrent marker (and the thread it runs in.)
823 ConcurrentMark* _cm;
824 ConcurrentMarkThread* _cmThread;
825
826 // The concurrent refiner.
827 ConcurrentG1Refine* _cg1r;
828
829 // The parallel task queues
830 RefToScanQueueSet *_task_queues;
831
832 // True iff a evacuation has failed in the current collection.
833 bool _evacuation_failed;
834
835 EvacuationFailedInfo* _evacuation_failed_info_array;
836
837 // Failed evacuations cause some logical from-space objects to have
838 // forwarding pointers to themselves. Reset them.
839 void remove_self_forwarding_pointers();
840
841 struct OopAndMarkOop {
842 private:
843 oop _o;
844 markOop _m;
845 public:
846 OopAndMarkOop(oop obj, markOop m) : _o(obj), _m(m) {
847 }
848
849 void set_mark() {
850 _o->set_mark(_m);
851 }
852 };
853
854 typedef Stack<OopAndMarkOop,mtGC> OopAndMarkOopStack;
855 // Stores marks with the corresponding oop that we need to preserve during evacuation
856 // failure.
857 OopAndMarkOopStack* _preserved_objs;
858
859 // Preserve the mark of "obj", if necessary, in preparation for its mark
860 // word being overwritten with a self-forwarding-pointer.
861 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m);
862
863 #ifndef PRODUCT
864 // Support for forcing evacuation failures. Analogous to
865 // PromotionFailureALot for the other collectors.
866
867 // Records whether G1EvacuationFailureALot should be in effect
868 // for the current GC
869 bool _evacuation_failure_alot_for_current_gc;
870
871 // Used to record the GC number for interval checking when
872 // determining whether G1EvaucationFailureALot is in effect
873 // for the current GC.
874 size_t _evacuation_failure_alot_gc_number;
875
876 // Count of the number of evacuations between failures.
877 volatile size_t _evacuation_failure_alot_count;
878
879 // Set whether G1EvacuationFailureALot should be in effect
880 // for the current GC (based upon the type of GC and which
881 // command line flags are set);
882 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young,
883 bool during_initial_mark,
884 bool during_marking);
885
886 inline void set_evacuation_failure_alot_for_current_gc();
887
888 // Return true if it's time to cause an evacuation failure.
889 inline bool evacuation_should_fail();
890
891 // Reset the G1EvacuationFailureALot counters. Should be called at
892 // the end of an evacuation pause in which an evacuation failure occurred.
893 inline void reset_evacuation_should_fail();
894 #endif // !PRODUCT
895
896 // ("Weak") Reference processing support.
897 //
898 // G1 has 2 instances of the reference processor class. One
899 // (_ref_processor_cm) handles reference object discovery
900 // and subsequent processing during concurrent marking cycles.
901 //
902 // The other (_ref_processor_stw) handles reference object
903 // discovery and processing during full GCs and incremental
904 // evacuation pauses.
905 //
906 // During an incremental pause, reference discovery will be
907 // temporarily disabled for _ref_processor_cm and will be
908 // enabled for _ref_processor_stw. At the end of the evacuation
909 // pause references discovered by _ref_processor_stw will be
910 // processed and discovery will be disabled. The previous
911 // setting for reference object discovery for _ref_processor_cm
912 // will be re-instated.
913 //
914 // At the start of marking:
915 // * Discovery by the CM ref processor is verified to be inactive
916 // and it's discovered lists are empty.
917 // * Discovery by the CM ref processor is then enabled.
918 //
919 // At the end of marking:
920 // * Any references on the CM ref processor's discovered
921 // lists are processed (possibly MT).
922 //
923 // At the start of full GC we:
924 // * Disable discovery by the CM ref processor and
925 // empty CM ref processor's discovered lists
926 // (without processing any entries).
927 // * Verify that the STW ref processor is inactive and it's
928 // discovered lists are empty.
929 // * Temporarily set STW ref processor discovery as single threaded.
930 // * Temporarily clear the STW ref processor's _is_alive_non_header
931 // field.
932 // * Finally enable discovery by the STW ref processor.
933 //
934 // The STW ref processor is used to record any discovered
935 // references during the full GC.
936 //
937 // At the end of a full GC we:
938 // * Enqueue any reference objects discovered by the STW ref processor
939 // that have non-live referents. This has the side-effect of
940 // making the STW ref processor inactive by disabling discovery.
941 // * Verify that the CM ref processor is still inactive
942 // and no references have been placed on it's discovered
943 // lists (also checked as a precondition during initial marking).
944
945 // The (stw) reference processor...
946 ReferenceProcessor* _ref_processor_stw;
947
948 STWGCTimer* _gc_timer_stw;
949 ConcurrentGCTimer* _gc_timer_cm;
950
951 G1OldTracer* _gc_tracer_cm;
952 G1NewTracer* _gc_tracer_stw;
953
954 // During reference object discovery, the _is_alive_non_header
955 // closure (if non-null) is applied to the referent object to
956 // determine whether the referent is live. If so then the
957 // reference object does not need to be 'discovered' and can
958 // be treated as a regular oop. This has the benefit of reducing
959 // the number of 'discovered' reference objects that need to
960 // be processed.
961 //
962 // Instance of the is_alive closure for embedding into the
963 // STW reference processor as the _is_alive_non_header field.
964 // Supplying a value for the _is_alive_non_header field is
965 // optional but doing so prevents unnecessary additions to
966 // the discovered lists during reference discovery.
967 G1STWIsAliveClosure _is_alive_closure_stw;
968
969 // The (concurrent marking) reference processor...
970 ReferenceProcessor* _ref_processor_cm;
971
972 // Instance of the concurrent mark is_alive closure for embedding
973 // into the Concurrent Marking reference processor as the
974 // _is_alive_non_header field. Supplying a value for the
975 // _is_alive_non_header field is optional but doing so prevents
976 // unnecessary additions to the discovered lists during reference
977 // discovery.
978 G1CMIsAliveClosure _is_alive_closure_cm;
979
980 // Cache used by G1CollectedHeap::start_cset_region_for_worker().
981 HeapRegion** _worker_cset_start_region;
982
983 // Time stamp to validate the regions recorded in the cache
984 // used by G1CollectedHeap::start_cset_region_for_worker().
985 // The heap region entry for a given worker is valid iff
986 // the associated time stamp value matches the current value
987 // of G1CollectedHeap::_gc_time_stamp.
988 uint* _worker_cset_start_region_time_stamp;
989
990 volatile bool _free_regions_coming;
991
992 public:
993
994 void set_refine_cte_cl_concurrency(bool concurrent);
995
996 RefToScanQueue *task_queue(uint i) const;
997
998 uint num_task_queues() const;
999
1000 // A set of cards where updates happened during the GC
1001 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
1002
1003 // A DirtyCardQueueSet that is used to hold cards that contain
1004 // references into the current collection set. This is used to
1005 // update the remembered sets of the regions in the collection
1006 // set in the event of an evacuation failure.
1007 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
1008 { return _into_cset_dirty_card_queue_set; }
1009
1010 // Create a G1CollectedHeap with the specified policy.
1011 // Must call the initialize method afterwards.
1012 // May not return if something goes wrong.
1013 G1CollectedHeap(G1CollectorPolicy* policy);
1014
1015 // Initialize the G1CollectedHeap to have the initial and
1016 // maximum sizes and remembered and barrier sets
1017 // specified by the policy object.
1018 jint initialize();
1019
1020 virtual void stop();
1021
1022 // Return the (conservative) maximum heap alignment for any G1 heap
1023 static size_t conservative_max_heap_alignment();
1024
1025 // Does operations required after initialization has been done.
1026 void post_initialize();
1027
1028 // Initialize weak reference processing.
1029 void ref_processing_init();
1030
1031 virtual Name kind() const {
1032 return CollectedHeap::G1CollectedHeap;
1033 }
1034
1035 G1CollectorState* collector_state() { return &_collector_state; }
1036
1037 // The current policy object for the collector.
1038 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
1039
1040 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); }
1041
1042 // Adaptive size policy. No such thing for g1.
1043 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
1044
1045 // The rem set and barrier set.
1046 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
1047
1048 unsigned get_gc_time_stamp() {
1049 return _gc_time_stamp;
1050 }
1051
1052 inline void reset_gc_time_stamp();
1053
1054 void check_gc_time_stamps() PRODUCT_RETURN;
1055
1056 inline void increment_gc_time_stamp();
1057
1058 // Reset the given region's GC timestamp. If it's starts humongous,
1059 // also reset the GC timestamp of its corresponding
1060 // continues humongous regions too.
1061 void reset_gc_time_stamps(HeapRegion* hr);
1062
1063 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
1064 DirtyCardQueue* into_cset_dcq,
1065 bool concurrent, uint worker_i);
1066
1067 // The shared block offset table array.
1068 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
1069
1070 // Reference Processing accessors
1071
1072 // The STW reference processor....
1073 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1074
1075 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; }
1076
1077 // The Concurrent Marking reference processor...
1078 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1079
1080 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; }
1081 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; }
1082
1083 virtual size_t capacity() const;
1084 virtual size_t used() const;
1085 // This should be called when we're not holding the heap lock. The
1086 // result might be a bit inaccurate.
1087 size_t used_unlocked() const;
1088 size_t recalculate_used() const;
1089
1090 // These virtual functions do the actual allocation.
1091 // Some heaps may offer a contiguous region for shared non-blocking
1092 // allocation, via inlined code (by exporting the address of the top and
1093 // end fields defining the extent of the contiguous allocation region.)
1094 // But G1CollectedHeap doesn't yet support this.
1095
1096 virtual bool is_maximal_no_gc() const {
1097 return _hrm.available() == 0;
1098 }
1099
1100 // The current number of regions in the heap.
1101 uint num_regions() const { return _hrm.length(); }
1102
1103 // The max number of regions in the heap.
1104 uint max_regions() const { return _hrm.max_length(); }
1105
1106 // The number of regions that are completely free.
1107 uint num_free_regions() const { return _hrm.num_free_regions(); }
1108
1109 MemoryUsage get_auxiliary_data_memory_usage() const {
1110 return _hrm.get_auxiliary_data_memory_usage();
1111 }
1112
1113 // The number of regions that are not completely free.
1114 uint num_used_regions() const { return num_regions() - num_free_regions(); }
1115
1116 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1117 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1118 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
1119 void verify_dirty_young_regions() PRODUCT_RETURN;
1120
1121 #ifndef PRODUCT
1122 // Make sure that the given bitmap has no marked objects in the
1123 // range [from,limit). If it does, print an error message and return
1124 // false. Otherwise, just return true. bitmap_name should be "prev"
1125 // or "next".
1126 bool verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
1127 HeapWord* from, HeapWord* limit);
1128
1129 // Verify that the prev / next bitmap range [tams,end) for the given
1130 // region has no marks. Return true if all is well, false if errors
1131 // are detected.
1132 bool verify_bitmaps(const char* caller, HeapRegion* hr);
1133 #endif // PRODUCT
1134
1135 // If G1VerifyBitmaps is set, verify that the marking bitmaps for
1136 // the given region do not have any spurious marks. If errors are
1137 // detected, print appropriate error messages and crash.
1138 void check_bitmaps(const char* caller, HeapRegion* hr) PRODUCT_RETURN;
1139
1140 // If G1VerifyBitmaps is set, verify that the marking bitmaps do not
1141 // have any spurious marks. If errors are detected, print
1142 // appropriate error messages and crash.
1143 void check_bitmaps(const char* caller) PRODUCT_RETURN;
1144
1145 // Do sanity check on the contents of the in-cset fast test table.
1146 bool check_cset_fast_test() PRODUCT_RETURN_( return true; );
1147
1148 // verify_region_sets() performs verification over the region
1149 // lists. It will be compiled in the product code to be used when
1150 // necessary (i.e., during heap verification).
1151 void verify_region_sets();
1152
1153 // verify_region_sets_optional() is planted in the code for
1154 // list verification in non-product builds (and it can be enabled in
1155 // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1).
1156 #if HEAP_REGION_SET_FORCE_VERIFY
1157 void verify_region_sets_optional() {
1158 verify_region_sets();
1159 }
1160 #else // HEAP_REGION_SET_FORCE_VERIFY
1161 void verify_region_sets_optional() { }
1162 #endif // HEAP_REGION_SET_FORCE_VERIFY
1163
1164 #ifdef ASSERT
1165 bool is_on_master_free_list(HeapRegion* hr) {
1166 return _hrm.is_free(hr);
1167 }
1168 #endif // ASSERT
1169
1170 // Wrapper for the region list operations that can be called from
1171 // methods outside this class.
1172
1173 void secondary_free_list_add(FreeRegionList* list) {
1174 _secondary_free_list.add_ordered(list);
1175 }
1176
1177 void append_secondary_free_list() {
1178 _hrm.insert_list_into_free_list(&_secondary_free_list);
1179 }
1180
1181 void append_secondary_free_list_if_not_empty_with_lock() {
1182 // If the secondary free list looks empty there's no reason to
1183 // take the lock and then try to append it.
1184 if (!_secondary_free_list.is_empty()) {
1185 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1186 append_secondary_free_list();
1187 }
1188 }
1189
1190 inline void old_set_add(HeapRegion* hr);
1191 inline void old_set_remove(HeapRegion* hr);
1192
1193 size_t non_young_capacity_bytes() {
1194 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes();
1195 }
1196
1197 void set_free_regions_coming();
1198 void reset_free_regions_coming();
1199 bool free_regions_coming() { return _free_regions_coming; }
1200 void wait_while_free_regions_coming();
1201
1202 // Determine whether the given region is one that we are using as an
1203 // old GC alloc region.
1204 bool is_old_gc_alloc_region(HeapRegion* hr) {
1205 return _allocator->is_retained_old_region(hr);
1206 }
1207
1208 // Perform a collection of the heap; intended for use in implementing
1209 // "System.gc". This probably implies as full a collection as the
1210 // "CollectedHeap" supports.
1211 virtual void collect(GCCause::Cause cause);
1212
1213 // The same as above but assume that the caller holds the Heap_lock.
1214 void collect_locked(GCCause::Cause cause);
1215
1216 virtual bool copy_allocation_context_stats(const jint* contexts,
1217 jlong* totals,
1218 jbyte* accuracy,
1219 jint len);
1220
1221 // True iff an evacuation has failed in the most-recent collection.
1222 bool evacuation_failed() { return _evacuation_failed; }
1223
1224 void remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, const HeapRegionSetCount& humongous_regions_removed);
1225 void prepend_to_freelist(FreeRegionList* list);
1226 void decrement_summary_bytes(size_t bytes);
1227
1228 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1229 virtual bool is_in(const void* p) const;
1230 #ifdef ASSERT
1231 // Returns whether p is in one of the available areas of the heap. Slow but
1232 // extensive version.
1233 bool is_in_exact(const void* p) const;
1234 #endif
1235
1236 // Return "TRUE" iff the given object address is within the collection
1237 // set. Slow implementation.
1238 bool obj_in_cs(oop obj);
1239
1240 inline bool is_in_cset(const HeapRegion *hr);
1241 inline bool is_in_cset(oop obj);
1242
1243 inline bool is_in_cset_or_humongous(const oop obj);
1244
1245 private:
1246 // This array is used for a quick test on whether a reference points into
1247 // the collection set or not. Each of the array's elements denotes whether the
1248 // corresponding region is in the collection set or not.
1249 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test;
1250
1251 public:
1252
1253 inline InCSetState in_cset_state(const oop obj);
1254
1255 // Return "TRUE" iff the given object address is in the reserved
1256 // region of g1.
1257 bool is_in_g1_reserved(const void* p) const {
1258 return _hrm.reserved().contains(p);
1259 }
1260
1261 // Returns a MemRegion that corresponds to the space that has been
1262 // reserved for the heap
1263 MemRegion g1_reserved() const {
1264 return _hrm.reserved();
1265 }
1266
1267 virtual bool is_in_closed_subset(const void* p) const;
1268
1269 G1SATBCardTableLoggingModRefBS* g1_barrier_set() {
1270 return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set());
1271 }
1272
1273 // This resets the card table to all zeros. It is used after
1274 // a collection pause which used the card table to claim cards.
1275 void cleanUpCardTable();
1276
1277 // Iteration functions.
1278
1279 // Iterate over all objects, calling "cl.do_object" on each.
1280 virtual void object_iterate(ObjectClosure* cl);
1281
1282 virtual void safe_object_iterate(ObjectClosure* cl) {
1283 object_iterate(cl);
1284 }
1285
1286 // Iterate over heap regions, in address order, terminating the
1287 // iteration early if the "doHeapRegion" method returns "true".
1288 void heap_region_iterate(HeapRegionClosure* blk) const;
1289
1290 // Return the region with the given index. It assumes the index is valid.
1291 inline HeapRegion* region_at(uint index) const;
1292
1293 // Calculate the region index of the given address. Given address must be
1294 // within the heap.
1295 inline uint addr_to_region(HeapWord* addr) const;
1296
1297 inline HeapWord* bottom_addr_for_region(uint index) const;
1298
1299 // Iterate over the heap regions in parallel. Assumes that this will be called
1300 // in parallel by ParallelGCThreads worker threads with distinct worker ids
1301 // in the range [0..max(ParallelGCThreads-1, 1)]. Applies "blk->doHeapRegion"
1302 // to each of the regions, by attempting to claim the region using the
1303 // HeapRegionClaimer and, if successful, applying the closure to the claimed
1304 // region. The concurrent argument should be set to true if iteration is
1305 // performed concurrently, during which no assumptions are made for consistent
1306 // attributes of the heap regions (as they might be modified while iterating).
1307 void heap_region_par_iterate(HeapRegionClosure* cl,
1308 uint worker_id,
1309 HeapRegionClaimer* hrclaimer,
1310 bool concurrent = false) const;
1311
1312 // Clear the cached cset start regions and (more importantly)
1313 // the time stamps. Called when we reset the GC time stamp.
1314 void clear_cset_start_regions();
1315
1316 // Given the id of a worker, obtain or calculate a suitable
1317 // starting region for iterating over the current collection set.
1318 HeapRegion* start_cset_region_for_worker(uint worker_i);
1319
1320 // Iterate over the regions (if any) in the current collection set.
1321 void collection_set_iterate(HeapRegionClosure* blk);
1322
1323 // As above but starting from region r
1324 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1325
1326 HeapRegion* next_compaction_region(const HeapRegion* from) const;
1327
1328 // Returns the HeapRegion that contains addr. addr must not be NULL.
1329 template <class T>
1330 inline HeapRegion* heap_region_containing_raw(const T addr) const;
1331
1332 // Returns the HeapRegion that contains addr. addr must not be NULL.
1333 // If addr is within a humongous continues region, it returns its humongous start region.
1334 template <class T>
1335 inline HeapRegion* heap_region_containing(const T addr) const;
1336
1337 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1338 // each address in the (reserved) heap is a member of exactly
1339 // one block. The defining characteristic of a block is that it is
1340 // possible to find its size, and thus to progress forward to the next
1341 // block. (Blocks may be of different sizes.) Thus, blocks may
1342 // represent Java objects, or they might be free blocks in a
1343 // free-list-based heap (or subheap), as long as the two kinds are
1344 // distinguishable and the size of each is determinable.
1345
1346 // Returns the address of the start of the "block" that contains the
1347 // address "addr". We say "blocks" instead of "object" since some heaps
1348 // may not pack objects densely; a chunk may either be an object or a
1349 // non-object.
1350 virtual HeapWord* block_start(const void* addr) const;
1351
1352 // Requires "addr" to be the start of a chunk, and returns its size.
1353 // "addr + size" is required to be the start of a new chunk, or the end
1354 // of the active area of the heap.
1355 virtual size_t block_size(const HeapWord* addr) const;
1356
1357 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1358 // the block is an object.
1359 virtual bool block_is_obj(const HeapWord* addr) const;
1360
1361 // Section on thread-local allocation buffers (TLABs)
1362 // See CollectedHeap for semantics.
1363
1364 bool supports_tlab_allocation() const;
1365 size_t tlab_capacity(Thread* ignored) const;
1366 size_t tlab_used(Thread* ignored) const;
1367 size_t max_tlab_size() const;
1368 size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1369
1370 // Can a compiler initialize a new object without store barriers?
1371 // This permission only extends from the creation of a new object
1372 // via a TLAB up to the first subsequent safepoint. If such permission
1373 // is granted for this heap type, the compiler promises to call
1374 // defer_store_barrier() below on any slow path allocation of
1375 // a new object for which such initializing store barriers will
1376 // have been elided. G1, like CMS, allows this, but should be
1377 // ready to provide a compensating write barrier as necessary
1378 // if that storage came out of a non-young region. The efficiency
1379 // of this implementation depends crucially on being able to
1380 // answer very efficiently in constant time whether a piece of
1381 // storage in the heap comes from a young region or not.
1382 // See ReduceInitialCardMarks.
1383 virtual bool can_elide_tlab_store_barriers() const {
1384 return true;
1385 }
1386
1387 virtual bool card_mark_must_follow_store() const {
1388 return true;
1389 }
1390
1391 inline bool is_in_young(const oop obj);
1392
1393 virtual bool is_scavengable(const void* addr);
1394
1395 // We don't need barriers for initializing stores to objects
1396 // in the young gen: for the SATB pre-barrier, there is no
1397 // pre-value that needs to be remembered; for the remembered-set
1398 // update logging post-barrier, we don't maintain remembered set
1399 // information for young gen objects.
1400 virtual inline bool can_elide_initializing_store_barrier(oop new_obj);
1401
1402 // Returns "true" iff the given word_size is "very large".
1403 static bool is_humongous(size_t word_size) {
1404 // Note this has to be strictly greater-than as the TLABs
1405 // are capped at the humongous threshold and we want to
1406 // ensure that we don't try to allocate a TLAB as
1407 // humongous and that we don't allocate a humongous
1408 // object in a TLAB.
1409 return word_size > _humongous_object_threshold_in_words;
1410 }
1411
1412 // Returns the humongous threshold for a specific region size
1413 static size_t humongous_threshold_for(size_t region_size) {
1414 return (region_size / 2);
1415 }
1416
1417 // Update mod union table with the set of dirty cards.
1418 void updateModUnion();
1419
1420 // Set the mod union bits corresponding to the given memRegion. Note
1421 // that this is always a safe operation, since it doesn't clear any
1422 // bits.
1423 void markModUnionRange(MemRegion mr);
1424
1425 // Print the maximum heap capacity.
1426 virtual size_t max_capacity() const;
1427
1428 virtual jlong millis_since_last_gc();
1429
1430
1431 // Convenience function to be used in situations where the heap type can be
1432 // asserted to be this type.
1433 static G1CollectedHeap* heap();
1434
1435 void set_region_short_lived_locked(HeapRegion* hr);
1436 // add appropriate methods for any other surv rate groups
1437
1438 YoungList* young_list() const { return _young_list; }
1439
1440 // debugging
1441 bool check_young_list_well_formed() {
1442 return _young_list->check_list_well_formed();
1443 }
1444
1445 bool check_young_list_empty(bool check_heap,
1446 bool check_sample = true);
1447
1448 // *** Stuff related to concurrent marking. It's not clear to me that so
1449 // many of these need to be public.
1450
1451 // The functions below are helper functions that a subclass of
1452 // "CollectedHeap" can use in the implementation of its virtual
1453 // functions.
1454 // This performs a concurrent marking of the live objects in a
1455 // bitmap off to the side.
1456 void doConcurrentMark();
1457
1458 bool isMarkedPrev(oop obj) const;
1459 bool isMarkedNext(oop obj) const;
1460
1461 // Determine if an object is dead, given the object and also
1462 // the region to which the object belongs. An object is dead
1463 // iff a) it was not allocated since the last mark, b) it
1464 // is not marked, and c) it is not in an archive region.
1465 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1466 return
1467 !hr->obj_allocated_since_prev_marking(obj) &&
1468 !isMarkedPrev(obj) &&
1469 !hr->is_archive();
1470 }
1471
1472 // This function returns true when an object has been
1473 // around since the previous marking and hasn't yet
1474 // been marked during this marking, and is not in an archive region.
1475 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1476 return
1477 !hr->obj_allocated_since_next_marking(obj) &&
1478 !isMarkedNext(obj) &&
1479 !hr->is_archive();
1480 }
1481
1482 // Determine if an object is dead, given only the object itself.
1483 // This will find the region to which the object belongs and
1484 // then call the region version of the same function.
1485
1486 // Added if it is NULL it isn't dead.
1487
1488 inline bool is_obj_dead(const oop obj) const;
1489
1490 inline bool is_obj_ill(const oop obj) const;
1491
1492 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo);
1493 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo);
1494 bool is_marked(oop obj, VerifyOption vo);
1495 const char* top_at_mark_start_str(VerifyOption vo);
1496
1497 ConcurrentMark* concurrent_mark() const { return _cm; }
1498
1499 // Refinement
1500
1501 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1502
1503 // The dirty cards region list is used to record a subset of regions
1504 // whose cards need clearing. The list if populated during the
1505 // remembered set scanning and drained during the card table
1506 // cleanup. Although the methods are reentrant, population/draining
1507 // phases must not overlap. For synchronization purposes the last
1508 // element on the list points to itself.
1509 HeapRegion* _dirty_cards_region_list;
1510 void push_dirty_cards_region(HeapRegion* hr);
1511 HeapRegion* pop_dirty_cards_region();
1512
1513 // Optimized nmethod scanning support routines
1514
1515 // Register the given nmethod with the G1 heap.
1516 virtual void register_nmethod(nmethod* nm);
1517
1518 // Unregister the given nmethod from the G1 heap.
1519 virtual void unregister_nmethod(nmethod* nm);
1520
1521 // Free up superfluous code root memory.
1522 void purge_code_root_memory();
1523
1524 // Rebuild the strong code root lists for each region
1525 // after a full GC.
1526 void rebuild_strong_code_roots();
1527
1528 // Delete entries for dead interned string and clean up unreferenced symbols
1529 // in symbol table, possibly in parallel.
1530 void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true);
1531
1532 // Parallel phase of unloading/cleaning after G1 concurrent mark.
1533 void parallel_cleaning(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool class_unloading_occurred);
1534
1535 // Redirty logged cards in the refinement queue.
1536 void redirty_logged_cards();
1537 // Verification
1538
1539 // Perform any cleanup actions necessary before allowing a verification.
1540 virtual void prepare_for_verify();
1541
1542 // Perform verification.
1543
1544 // vo == UsePrevMarking -> use "prev" marking information,
1545 // vo == UseNextMarking -> use "next" marking information
1546 // vo == UseMarkWord -> use the mark word in the object header
1547 //
1548 // NOTE: Only the "prev" marking information is guaranteed to be
1549 // consistent most of the time, so most calls to this should use
1550 // vo == UsePrevMarking.
1551 // Currently, there is only one case where this is called with
1552 // vo == UseNextMarking, which is to verify the "next" marking
1553 // information at the end of remark.
1554 // Currently there is only one place where this is called with
1555 // vo == UseMarkWord, which is to verify the marking during a
1556 // full GC.
1557 void verify(bool silent, VerifyOption vo);
1558
1559 // Override; it uses the "prev" marking information
1560 virtual void verify(bool silent);
1561
1562 // The methods below are here for convenience and dispatch the
1563 // appropriate method depending on value of the given VerifyOption
1564 // parameter. The values for that parameter, and their meanings,
1565 // are the same as those above.
1566
1567 bool is_obj_dead_cond(const oop obj,
1568 const HeapRegion* hr,
1569 const VerifyOption vo) const;
1570
1571 bool is_obj_dead_cond(const oop obj,
1572 const VerifyOption vo) const;
1573
1574 G1HeapSummary create_g1_heap_summary();
1575
1576 // Printing
1577
1578 virtual void print_on(outputStream* st) const;
1579 virtual void print_extended_on(outputStream* st) const;
1580 virtual void print_on_error(outputStream* st) const;
1581
1582 virtual void print_gc_threads_on(outputStream* st) const;
1583 virtual void gc_threads_do(ThreadClosure* tc) const;
1584
1585 // Override
1586 void print_tracing_info() const;
1587
1588 // The following two methods are helpful for debugging RSet issues.
1589 void print_cset_rsets() PRODUCT_RETURN;
1590 void print_all_rsets() PRODUCT_RETURN;
1591
1592 public:
1593 size_t pending_card_num();
1594 size_t cards_scanned();
1595
1596 protected:
1597 size_t _max_heap_capacity;
1598 };
1599
1600 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP