Tue, 31 Mar 2015 11:36:37 +0200
8068036: assert(is_available(index)) failed in G1 cset
Summary: Some verification code iterated over the heap using the region mapping array. This is not allowed. Changed to use the regular iteration method with closure.
Reviewed-by: jwilhelm, brutisso
1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP
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"
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.
53 // Forward declarations
54 class HeapRegion;
55 class HRRSCleanupTask;
56 class GenerationSpec;
57 class OopsInHeapRegionClosure;
58 class G1KlassScanClosure;
59 class G1ScanHeapEvacClosure;
60 class ObjectClosure;
61 class SpaceClosure;
62 class CompactibleSpaceClosure;
63 class Space;
64 class G1CollectorPolicy;
65 class GenRemSet;
66 class G1RemSet;
67 class HeapRegionRemSetIterator;
68 class ConcurrentMark;
69 class ConcurrentMarkThread;
70 class ConcurrentG1Refine;
71 class ConcurrentGCTimer;
72 class GenerationCounters;
73 class STWGCTimer;
74 class G1NewTracer;
75 class G1OldTracer;
76 class EvacuationFailedInfo;
77 class nmethod;
78 class Ticks;
80 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue;
81 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
83 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
84 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
86 class YoungList : public CHeapObj<mtGC> {
87 private:
88 G1CollectedHeap* _g1h;
90 HeapRegion* _head;
92 HeapRegion* _survivor_head;
93 HeapRegion* _survivor_tail;
95 HeapRegion* _curr;
97 uint _length;
98 uint _survivor_length;
100 size_t _last_sampled_rs_lengths;
101 size_t _sampled_rs_lengths;
103 void empty_list(HeapRegion* list);
105 public:
106 YoungList(G1CollectedHeap* g1h);
108 void push_region(HeapRegion* hr);
109 void add_survivor_region(HeapRegion* hr);
111 void empty_list();
112 bool is_empty() { return _length == 0; }
113 uint length() { return _length; }
114 uint survivor_length() { return _survivor_length; }
116 // Currently we do not keep track of the used byte sum for the
117 // young list and the survivors and it'd be quite a lot of work to
118 // do so. When we'll eventually replace the young list with
119 // instances of HeapRegionLinkedList we'll get that for free. So,
120 // we'll report the more accurate information then.
121 size_t eden_used_bytes() {
122 assert(length() >= survivor_length(), "invariant");
123 return (size_t) (length() - survivor_length()) * HeapRegion::GrainBytes;
124 }
125 size_t survivor_used_bytes() {
126 return (size_t) survivor_length() * HeapRegion::GrainBytes;
127 }
129 void rs_length_sampling_init();
130 bool rs_length_sampling_more();
131 void rs_length_sampling_next();
133 void reset_sampled_info() {
134 _last_sampled_rs_lengths = 0;
135 }
136 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }
138 // for development purposes
139 void reset_auxilary_lists();
140 void clear() { _head = NULL; _length = 0; }
142 void clear_survivors() {
143 _survivor_head = NULL;
144 _survivor_tail = NULL;
145 _survivor_length = 0;
146 }
148 HeapRegion* first_region() { return _head; }
149 HeapRegion* first_survivor_region() { return _survivor_head; }
150 HeapRegion* last_survivor_region() { return _survivor_tail; }
152 // debugging
153 bool check_list_well_formed();
154 bool check_list_empty(bool check_sample = true);
155 void print();
156 };
158 // The G1 STW is alive closure.
159 // An instance is embedded into the G1CH and used as the
160 // (optional) _is_alive_non_header closure in the STW
161 // reference processor. It is also extensively used during
162 // reference processing during STW evacuation pauses.
163 class G1STWIsAliveClosure: public BoolObjectClosure {
164 G1CollectedHeap* _g1;
165 public:
166 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
167 bool do_object_b(oop p);
168 };
170 class RefineCardTableEntryClosure;
172 class G1RegionMappingChangedListener : public G1MappingChangedListener {
173 private:
174 void reset_from_card_cache(uint start_idx, size_t num_regions);
175 public:
176 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
177 };
179 class G1CollectedHeap : public SharedHeap {
180 friend class VM_CollectForMetadataAllocation;
181 friend class VM_G1CollectForAllocation;
182 friend class VM_G1CollectFull;
183 friend class VM_G1IncCollectionPause;
184 friend class VMStructs;
185 friend class MutatorAllocRegion;
186 friend class SurvivorGCAllocRegion;
187 friend class OldGCAllocRegion;
188 friend class G1Allocator;
189 friend class G1DefaultAllocator;
190 friend class G1ResManAllocator;
192 // Closures used in implementation.
193 template <G1Barrier barrier, G1Mark do_mark_object>
194 friend class G1ParCopyClosure;
195 friend class G1IsAliveClosure;
196 friend class G1EvacuateFollowersClosure;
197 friend class G1ParScanThreadState;
198 friend class G1ParScanClosureSuper;
199 friend class G1ParEvacuateFollowersClosure;
200 friend class G1ParTask;
201 friend class G1ParGCAllocator;
202 friend class G1DefaultParGCAllocator;
203 friend class G1FreeGarbageRegionClosure;
204 friend class RefineCardTableEntryClosure;
205 friend class G1PrepareCompactClosure;
206 friend class RegionSorter;
207 friend class RegionResetter;
208 friend class CountRCClosure;
209 friend class EvacPopObjClosure;
210 friend class G1ParCleanupCTTask;
212 friend class G1FreeHumongousRegionClosure;
213 // Other related classes.
214 friend class G1MarkSweep;
216 // Testing classes.
217 friend class G1CheckCSetFastTableClosure;
219 private:
220 // The one and only G1CollectedHeap, so static functions can find it.
221 static G1CollectedHeap* _g1h;
223 static size_t _humongous_object_threshold_in_words;
225 // The secondary free list which contains regions that have been
226 // freed up during the cleanup process. This will be appended to
227 // the master free list when appropriate.
228 FreeRegionList _secondary_free_list;
230 // It keeps track of the old regions.
231 HeapRegionSet _old_set;
233 // It keeps track of the humongous regions.
234 HeapRegionSet _humongous_set;
236 void clear_humongous_is_live_table();
237 void eagerly_reclaim_humongous_regions();
239 // The number of regions we could create by expansion.
240 uint _expansion_regions;
242 // The block offset table for the G1 heap.
243 G1BlockOffsetSharedArray* _bot_shared;
245 // Tears down the region sets / lists so that they are empty and the
246 // regions on the heap do not belong to a region set / list. The
247 // only exception is the humongous set which we leave unaltered. If
248 // free_list_only is true, it will only tear down the master free
249 // list. It is called before a Full GC (free_list_only == false) or
250 // before heap shrinking (free_list_only == true).
251 void tear_down_region_sets(bool free_list_only);
253 // Rebuilds the region sets / lists so that they are repopulated to
254 // reflect the contents of the heap. The only exception is the
255 // humongous set which was not torn down in the first place. If
256 // free_list_only is true, it will only rebuild the master free
257 // list. It is called after a Full GC (free_list_only == false) or
258 // after heap shrinking (free_list_only == true).
259 void rebuild_region_sets(bool free_list_only);
261 // Callback for region mapping changed events.
262 G1RegionMappingChangedListener _listener;
264 // The sequence of all heap regions in the heap.
265 HeapRegionManager _hrm;
267 // Class that handles the different kinds of allocations.
268 G1Allocator* _allocator;
270 // Statistics for each allocation context
271 AllocationContextStats _allocation_context_stats;
273 // PLAB sizing policy for survivors.
274 PLABStats _survivor_plab_stats;
276 // PLAB sizing policy for tenured objects.
277 PLABStats _old_plab_stats;
279 // It specifies whether we should attempt to expand the heap after a
280 // region allocation failure. If heap expansion fails we set this to
281 // false so that we don't re-attempt the heap expansion (it's likely
282 // that subsequent expansion attempts will also fail if one fails).
283 // Currently, it is only consulted during GC and it's reset at the
284 // start of each GC.
285 bool _expand_heap_after_alloc_failure;
287 // It resets the mutator alloc region before new allocations can take place.
288 void init_mutator_alloc_region();
290 // It releases the mutator alloc region.
291 void release_mutator_alloc_region();
293 // It initializes the GC alloc regions at the start of a GC.
294 void init_gc_alloc_regions(EvacuationInfo& evacuation_info);
296 // It releases the GC alloc regions at the end of a GC.
297 void release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info);
299 // It does any cleanup that needs to be done on the GC alloc regions
300 // before a Full GC.
301 void abandon_gc_alloc_regions();
303 // Helper for monitoring and management support.
304 G1MonitoringSupport* _g1mm;
306 // Records whether the region at the given index is kept live by roots or
307 // references from the young generation.
308 class HumongousIsLiveBiasedMappedArray : public G1BiasedMappedArray<bool> {
309 protected:
310 bool default_value() const { return false; }
311 public:
312 void clear() { G1BiasedMappedArray<bool>::clear(); }
313 void set_live(uint region) {
314 set_by_index(region, true);
315 }
316 bool is_live(uint region) {
317 return get_by_index(region);
318 }
319 };
321 HumongousIsLiveBiasedMappedArray _humongous_is_live;
322 // Stores whether during humongous object registration we found candidate regions.
323 // If not, we can skip a few steps.
324 bool _has_humongous_reclaim_candidates;
326 volatile unsigned _gc_time_stamp;
328 size_t* _surviving_young_words;
330 G1HRPrinter _hr_printer;
332 void setup_surviving_young_words();
333 void update_surviving_young_words(size_t* surv_young_words);
334 void cleanup_surviving_young_words();
336 // It decides whether an explicit GC should start a concurrent cycle
337 // instead of doing a STW GC. Currently, a concurrent cycle is
338 // explicitly started if:
339 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
340 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
341 // (c) cause == _g1_humongous_allocation
342 bool should_do_concurrent_full_gc(GCCause::Cause cause);
344 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
345 // concurrent cycles) we have started.
346 volatile unsigned int _old_marking_cycles_started;
348 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
349 // concurrent cycles) we have completed.
350 volatile unsigned int _old_marking_cycles_completed;
352 bool _concurrent_cycle_started;
353 bool _heap_summary_sent;
355 // This is a non-product method that is helpful for testing. It is
356 // called at the end of a GC and artificially expands the heap by
357 // allocating a number of dead regions. This way we can induce very
358 // frequent marking cycles and stress the cleanup / concurrent
359 // cleanup code more (as all the regions that will be allocated by
360 // this method will be found dead by the marking cycle).
361 void allocate_dummy_regions() PRODUCT_RETURN;
363 // Clear RSets after a compaction. It also resets the GC time stamps.
364 void clear_rsets_post_compaction();
366 // If the HR printer is active, dump the state of the regions in the
367 // heap after a compaction.
368 void print_hrm_post_compaction();
370 double verify(bool guard, const char* msg);
371 void verify_before_gc();
372 void verify_after_gc();
374 void log_gc_header();
375 void log_gc_footer(double pause_time_sec);
377 // These are macros so that, if the assert fires, we get the correct
378 // line number, file, etc.
380 #define heap_locking_asserts_err_msg(_extra_message_) \
381 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
382 (_extra_message_), \
383 BOOL_TO_STR(Heap_lock->owned_by_self()), \
384 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
385 BOOL_TO_STR(Thread::current()->is_VM_thread()))
387 #define assert_heap_locked() \
388 do { \
389 assert(Heap_lock->owned_by_self(), \
390 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
391 } while (0)
393 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
394 do { \
395 assert(Heap_lock->owned_by_self() || \
396 (SafepointSynchronize::is_at_safepoint() && \
397 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
398 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
399 "should be at a safepoint")); \
400 } while (0)
402 #define assert_heap_locked_and_not_at_safepoint() \
403 do { \
404 assert(Heap_lock->owned_by_self() && \
405 !SafepointSynchronize::is_at_safepoint(), \
406 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
407 "should not be at a safepoint")); \
408 } while (0)
410 #define assert_heap_not_locked() \
411 do { \
412 assert(!Heap_lock->owned_by_self(), \
413 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
414 } while (0)
416 #define assert_heap_not_locked_and_not_at_safepoint() \
417 do { \
418 assert(!Heap_lock->owned_by_self() && \
419 !SafepointSynchronize::is_at_safepoint(), \
420 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
421 "should not be at a safepoint")); \
422 } while (0)
424 #define assert_at_safepoint(_should_be_vm_thread_) \
425 do { \
426 assert(SafepointSynchronize::is_at_safepoint() && \
427 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
428 heap_locking_asserts_err_msg("should be at a safepoint")); \
429 } while (0)
431 #define assert_not_at_safepoint() \
432 do { \
433 assert(!SafepointSynchronize::is_at_safepoint(), \
434 heap_locking_asserts_err_msg("should not be at a safepoint")); \
435 } while (0)
437 protected:
439 // The young region list.
440 YoungList* _young_list;
442 // The current policy object for the collector.
443 G1CollectorPolicy* _g1_policy;
445 // This is the second level of trying to allocate a new region. If
446 // new_region() didn't find a region on the free_list, this call will
447 // check whether there's anything available on the
448 // secondary_free_list and/or wait for more regions to appear on
449 // that list, if _free_regions_coming is set.
450 HeapRegion* new_region_try_secondary_free_list(bool is_old);
452 // Try to allocate a single non-humongous HeapRegion sufficient for
453 // an allocation of the given word_size. If do_expand is true,
454 // attempt to expand the heap if necessary to satisfy the allocation
455 // request. If the region is to be used as an old region or for a
456 // humongous object, set is_old to true. If not, to false.
457 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand);
459 // Initialize a contiguous set of free regions of length num_regions
460 // and starting at index first so that they appear as a single
461 // humongous region.
462 HeapWord* humongous_obj_allocate_initialize_regions(uint first,
463 uint num_regions,
464 size_t word_size,
465 AllocationContext_t context);
467 // Attempt to allocate a humongous object of the given size. Return
468 // NULL if unsuccessful.
469 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context);
471 // The following two methods, allocate_new_tlab() and
472 // mem_allocate(), are the two main entry points from the runtime
473 // into the G1's allocation routines. They have the following
474 // assumptions:
475 //
476 // * They should both be called outside safepoints.
477 //
478 // * They should both be called without holding the Heap_lock.
479 //
480 // * All allocation requests for new TLABs should go to
481 // allocate_new_tlab().
482 //
483 // * All non-TLAB allocation requests should go to mem_allocate().
484 //
485 // * If either call cannot satisfy the allocation request using the
486 // current allocating region, they will try to get a new one. If
487 // this fails, they will attempt to do an evacuation pause and
488 // retry the allocation.
489 //
490 // * If all allocation attempts fail, even after trying to schedule
491 // an evacuation pause, allocate_new_tlab() will return NULL,
492 // whereas mem_allocate() will attempt a heap expansion and/or
493 // schedule a Full GC.
494 //
495 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
496 // should never be called with word_size being humongous. All
497 // humongous allocation requests should go to mem_allocate() which
498 // will satisfy them with a special path.
500 virtual HeapWord* allocate_new_tlab(size_t word_size);
502 virtual HeapWord* mem_allocate(size_t word_size,
503 bool* gc_overhead_limit_was_exceeded);
505 // The following three methods take a gc_count_before_ret
506 // parameter which is used to return the GC count if the method
507 // returns NULL. Given that we are required to read the GC count
508 // while holding the Heap_lock, and these paths will take the
509 // Heap_lock at some point, it's easier to get them to read the GC
510 // count while holding the Heap_lock before they return NULL instead
511 // of the caller (namely: mem_allocate()) having to also take the
512 // Heap_lock just to read the GC count.
514 // First-level mutator allocation attempt: try to allocate out of
515 // the mutator alloc region without taking the Heap_lock. This
516 // should only be used for non-humongous allocations.
517 inline HeapWord* attempt_allocation(size_t word_size,
518 unsigned int* gc_count_before_ret,
519 int* gclocker_retry_count_ret);
521 // Second-level mutator allocation attempt: take the Heap_lock and
522 // retry the allocation attempt, potentially scheduling a GC
523 // pause. This should only be used for non-humongous allocations.
524 HeapWord* attempt_allocation_slow(size_t word_size,
525 AllocationContext_t context,
526 unsigned int* gc_count_before_ret,
527 int* gclocker_retry_count_ret);
529 // Takes the Heap_lock and attempts a humongous allocation. It can
530 // potentially schedule a GC pause.
531 HeapWord* attempt_allocation_humongous(size_t word_size,
532 unsigned int* gc_count_before_ret,
533 int* gclocker_retry_count_ret);
535 // Allocation attempt that should be called during safepoints (e.g.,
536 // at the end of a successful GC). expect_null_mutator_alloc_region
537 // specifies whether the mutator alloc region is expected to be NULL
538 // or not.
539 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
540 AllocationContext_t context,
541 bool expect_null_mutator_alloc_region);
543 // It dirties the cards that cover the block so that so that the post
544 // write barrier never queues anything when updating objects on this
545 // block. It is assumed (and in fact we assert) that the block
546 // belongs to a young region.
547 inline void dirty_young_block(HeapWord* start, size_t word_size);
549 // Allocate blocks during garbage collection. Will ensure an
550 // allocation region, either by picking one or expanding the
551 // heap, and then allocate a block of the given size. The block
552 // may not be a humongous - it must fit into a single heap region.
553 inline HeapWord* par_allocate_during_gc(InCSetState dest,
554 size_t word_size,
555 AllocationContext_t context);
556 // Ensure that no further allocations can happen in "r", bearing in mind
557 // that parallel threads might be attempting allocations.
558 void par_allocate_remaining_space(HeapRegion* r);
560 // Allocation attempt during GC for a survivor object / PLAB.
561 inline HeapWord* survivor_attempt_allocation(size_t word_size,
562 AllocationContext_t context);
564 // Allocation attempt during GC for an old object / PLAB.
565 inline HeapWord* old_attempt_allocation(size_t word_size,
566 AllocationContext_t context);
568 // These methods are the "callbacks" from the G1AllocRegion class.
570 // For mutator alloc regions.
571 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
572 void retire_mutator_alloc_region(HeapRegion* alloc_region,
573 size_t allocated_bytes);
575 // For GC alloc regions.
576 HeapRegion* new_gc_alloc_region(size_t word_size, uint count,
577 InCSetState dest);
578 void retire_gc_alloc_region(HeapRegion* alloc_region,
579 size_t allocated_bytes, InCSetState dest);
581 // - if explicit_gc is true, the GC is for a System.gc() or a heap
582 // inspection request and should collect the entire heap
583 // - if clear_all_soft_refs is true, all soft references should be
584 // cleared during the GC
585 // - if explicit_gc is false, word_size describes the allocation that
586 // the GC should attempt (at least) to satisfy
587 // - it returns false if it is unable to do the collection due to the
588 // GC locker being active, true otherwise
589 bool do_collection(bool explicit_gc,
590 bool clear_all_soft_refs,
591 size_t word_size);
593 // Callback from VM_G1CollectFull operation.
594 // Perform a full collection.
595 virtual void do_full_collection(bool clear_all_soft_refs);
597 // Resize the heap if necessary after a full collection. If this is
598 // after a collect-for allocation, "word_size" is the allocation size,
599 // and will be considered part of the used portion of the heap.
600 void resize_if_necessary_after_full_collection(size_t word_size);
602 // Callback from VM_G1CollectForAllocation operation.
603 // This function does everything necessary/possible to satisfy a
604 // failed allocation request (including collection, expansion, etc.)
605 HeapWord* satisfy_failed_allocation(size_t word_size,
606 AllocationContext_t context,
607 bool* succeeded);
609 // Attempting to expand the heap sufficiently
610 // to support an allocation of the given "word_size". If
611 // successful, perform the allocation and return the address of the
612 // allocated block, or else "NULL".
613 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context);
615 // Process any reference objects discovered during
616 // an incremental evacuation pause.
617 void process_discovered_references(uint no_of_gc_workers);
619 // Enqueue any remaining discovered references
620 // after processing.
621 void enqueue_discovered_references(uint no_of_gc_workers);
623 public:
625 G1Allocator* allocator() {
626 return _allocator;
627 }
629 G1MonitoringSupport* g1mm() {
630 assert(_g1mm != NULL, "should have been initialized");
631 return _g1mm;
632 }
634 // Expand the garbage-first heap by at least the given size (in bytes!).
635 // Returns true if the heap was expanded by the requested amount;
636 // false otherwise.
637 // (Rounds up to a HeapRegion boundary.)
638 bool expand(size_t expand_bytes);
640 // Returns the PLAB statistics for a given destination.
641 inline PLABStats* alloc_buffer_stats(InCSetState dest);
643 // Determines PLAB size for a given destination.
644 inline size_t desired_plab_sz(InCSetState dest);
646 inline AllocationContextStats& allocation_context_stats();
648 // Do anything common to GC's.
649 virtual void gc_prologue(bool full);
650 virtual void gc_epilogue(bool full);
652 inline void set_humongous_is_live(oop obj);
654 bool humongous_is_live(uint region) {
655 return _humongous_is_live.is_live(region);
656 }
658 // Returns whether the given region (which must be a humongous (start) region)
659 // is to be considered conservatively live regardless of any other conditions.
660 bool humongous_region_is_always_live(uint index);
661 // Register the given region to be part of the collection set.
662 inline void register_humongous_region_with_in_cset_fast_test(uint index);
663 // Register regions with humongous objects (actually on the start region) in
664 // the in_cset_fast_test table.
665 void register_humongous_regions_with_in_cset_fast_test();
666 // We register a region with the fast "in collection set" test. We
667 // simply set to true the array slot corresponding to this region.
668 void register_young_region_with_in_cset_fast_test(HeapRegion* r) {
669 _in_cset_fast_test.set_in_young(r->hrm_index());
670 }
671 void register_old_region_with_in_cset_fast_test(HeapRegion* r) {
672 _in_cset_fast_test.set_in_old(r->hrm_index());
673 }
675 // This is a fast test on whether a reference points into the
676 // collection set or not. Assume that the reference
677 // points into the heap.
678 inline bool in_cset_fast_test(oop obj);
680 void clear_cset_fast_test() {
681 _in_cset_fast_test.clear();
682 }
684 // This is called at the start of either a concurrent cycle or a Full
685 // GC to update the number of old marking cycles started.
686 void increment_old_marking_cycles_started();
688 // This is called at the end of either a concurrent cycle or a Full
689 // GC to update the number of old marking cycles completed. Those two
690 // can happen in a nested fashion, i.e., we start a concurrent
691 // cycle, a Full GC happens half-way through it which ends first,
692 // and then the cycle notices that a Full GC happened and ends
693 // too. The concurrent parameter is a boolean to help us do a bit
694 // tighter consistency checking in the method. If concurrent is
695 // false, the caller is the inner caller in the nesting (i.e., the
696 // Full GC). If concurrent is true, the caller is the outer caller
697 // in this nesting (i.e., the concurrent cycle). Further nesting is
698 // not currently supported. The end of this call also notifies
699 // the FullGCCount_lock in case a Java thread is waiting for a full
700 // GC to happen (e.g., it called System.gc() with
701 // +ExplicitGCInvokesConcurrent).
702 void increment_old_marking_cycles_completed(bool concurrent);
704 unsigned int old_marking_cycles_completed() {
705 return _old_marking_cycles_completed;
706 }
708 void register_concurrent_cycle_start(const Ticks& start_time);
709 void register_concurrent_cycle_end();
710 void trace_heap_after_concurrent_cycle();
712 G1YCType yc_type();
714 G1HRPrinter* hr_printer() { return &_hr_printer; }
716 // Frees a non-humongous region by initializing its contents and
717 // adding it to the free list that's passed as a parameter (this is
718 // usually a local list which will be appended to the master free
719 // list later). The used bytes of freed regions are accumulated in
720 // pre_used. If par is true, the region's RSet will not be freed
721 // up. The assumption is that this will be done later.
722 // The locked parameter indicates if the caller has already taken
723 // care of proper synchronization. This may allow some optimizations.
724 void free_region(HeapRegion* hr,
725 FreeRegionList* free_list,
726 bool par,
727 bool locked = false);
729 // Frees a humongous region by collapsing it into individual regions
730 // and calling free_region() for each of them. The freed regions
731 // will be added to the free list that's passed as a parameter (this
732 // is usually a local list which will be appended to the master free
733 // list later). The used bytes of freed regions are accumulated in
734 // pre_used. If par is true, the region's RSet will not be freed
735 // up. The assumption is that this will be done later.
736 void free_humongous_region(HeapRegion* hr,
737 FreeRegionList* free_list,
738 bool par);
739 protected:
741 // Shrink the garbage-first heap by at most the given size (in bytes!).
742 // (Rounds down to a HeapRegion boundary.)
743 virtual void shrink(size_t expand_bytes);
744 void shrink_helper(size_t expand_bytes);
746 #if TASKQUEUE_STATS
747 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
748 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
749 void reset_taskqueue_stats();
750 #endif // TASKQUEUE_STATS
752 // Schedule the VM operation that will do an evacuation pause to
753 // satisfy an allocation request of word_size. *succeeded will
754 // return whether the VM operation was successful (it did do an
755 // evacuation pause) or not (another thread beat us to it or the GC
756 // locker was active). Given that we should not be holding the
757 // Heap_lock when we enter this method, we will pass the
758 // gc_count_before (i.e., total_collections()) as a parameter since
759 // it has to be read while holding the Heap_lock. Currently, both
760 // methods that call do_collection_pause() release the Heap_lock
761 // before the call, so it's easy to read gc_count_before just before.
762 HeapWord* do_collection_pause(size_t word_size,
763 unsigned int gc_count_before,
764 bool* succeeded,
765 GCCause::Cause gc_cause);
767 // The guts of the incremental collection pause, executed by the vm
768 // thread. It returns false if it is unable to do the collection due
769 // to the GC locker being active, true otherwise
770 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
772 // Actually do the work of evacuating the collection set.
773 void evacuate_collection_set(EvacuationInfo& evacuation_info);
775 // The g1 remembered set of the heap.
776 G1RemSet* _g1_rem_set;
778 // A set of cards that cover the objects for which the Rsets should be updated
779 // concurrently after the collection.
780 DirtyCardQueueSet _dirty_card_queue_set;
782 // The closure used to refine a single card.
783 RefineCardTableEntryClosure* _refine_cte_cl;
785 // A function to check the consistency of dirty card logs.
786 void check_ct_logs_at_safepoint();
788 // A DirtyCardQueueSet that is used to hold cards that contain
789 // references into the current collection set. This is used to
790 // update the remembered sets of the regions in the collection
791 // set in the event of an evacuation failure.
792 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
794 // After a collection pause, make the regions in the CS into free
795 // regions.
796 void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info);
798 // Abandon the current collection set without recording policy
799 // statistics or updating free lists.
800 void abandon_collection_set(HeapRegion* cs_head);
802 // The concurrent marker (and the thread it runs in.)
803 ConcurrentMark* _cm;
804 ConcurrentMarkThread* _cmThread;
805 bool _mark_in_progress;
807 // The concurrent refiner.
808 ConcurrentG1Refine* _cg1r;
810 // The parallel task queues
811 RefToScanQueueSet *_task_queues;
813 // True iff a evacuation has failed in the current collection.
814 bool _evacuation_failed;
816 EvacuationFailedInfo* _evacuation_failed_info_array;
818 // Failed evacuations cause some logical from-space objects to have
819 // forwarding pointers to themselves. Reset them.
820 void remove_self_forwarding_pointers();
822 // Together, these store an object with a preserved mark, and its mark value.
823 Stack<oop, mtGC> _objs_with_preserved_marks;
824 Stack<markOop, mtGC> _preserved_marks_of_objs;
826 // Preserve the mark of "obj", if necessary, in preparation for its mark
827 // word being overwritten with a self-forwarding-pointer.
828 void preserve_mark_if_necessary(oop obj, markOop m);
830 // The stack of evac-failure objects left to be scanned.
831 GrowableArray<oop>* _evac_failure_scan_stack;
832 // The closure to apply to evac-failure objects.
834 OopsInHeapRegionClosure* _evac_failure_closure;
835 // Set the field above.
836 void
837 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
838 _evac_failure_closure = evac_failure_closure;
839 }
841 // Push "obj" on the scan stack.
842 void push_on_evac_failure_scan_stack(oop obj);
843 // Process scan stack entries until the stack is empty.
844 void drain_evac_failure_scan_stack();
845 // True iff an invocation of "drain_scan_stack" is in progress; to
846 // prevent unnecessary recursion.
847 bool _drain_in_progress;
849 // Do any necessary initialization for evacuation-failure handling.
850 // "cl" is the closure that will be used to process evac-failure
851 // objects.
852 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
853 // Do any necessary cleanup for evacuation-failure handling data
854 // structures.
855 void finalize_for_evac_failure();
857 // An attempt to evacuate "obj" has failed; take necessary steps.
858 oop handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, oop obj);
859 void handle_evacuation_failure_common(oop obj, markOop m);
861 #ifndef PRODUCT
862 // Support for forcing evacuation failures. Analogous to
863 // PromotionFailureALot for the other collectors.
865 // Records whether G1EvacuationFailureALot should be in effect
866 // for the current GC
867 bool _evacuation_failure_alot_for_current_gc;
869 // Used to record the GC number for interval checking when
870 // determining whether G1EvaucationFailureALot is in effect
871 // for the current GC.
872 size_t _evacuation_failure_alot_gc_number;
874 // Count of the number of evacuations between failures.
875 volatile size_t _evacuation_failure_alot_count;
877 // Set whether G1EvacuationFailureALot should be in effect
878 // for the current GC (based upon the type of GC and which
879 // command line flags are set);
880 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young,
881 bool during_initial_mark,
882 bool during_marking);
884 inline void set_evacuation_failure_alot_for_current_gc();
886 // Return true if it's time to cause an evacuation failure.
887 inline bool evacuation_should_fail();
889 // Reset the G1EvacuationFailureALot counters. Should be called at
890 // the end of an evacuation pause in which an evacuation failure occurred.
891 inline void reset_evacuation_should_fail();
892 #endif // !PRODUCT
894 // ("Weak") Reference processing support.
895 //
896 // G1 has 2 instances of the reference processor class. One
897 // (_ref_processor_cm) handles reference object discovery
898 // and subsequent processing during concurrent marking cycles.
899 //
900 // The other (_ref_processor_stw) handles reference object
901 // discovery and processing during full GCs and incremental
902 // evacuation pauses.
903 //
904 // During an incremental pause, reference discovery will be
905 // temporarily disabled for _ref_processor_cm and will be
906 // enabled for _ref_processor_stw. At the end of the evacuation
907 // pause references discovered by _ref_processor_stw will be
908 // processed and discovery will be disabled. The previous
909 // setting for reference object discovery for _ref_processor_cm
910 // will be re-instated.
911 //
912 // At the start of marking:
913 // * Discovery by the CM ref processor is verified to be inactive
914 // and it's discovered lists are empty.
915 // * Discovery by the CM ref processor is then enabled.
916 //
917 // At the end of marking:
918 // * Any references on the CM ref processor's discovered
919 // lists are processed (possibly MT).
920 //
921 // At the start of full GC we:
922 // * Disable discovery by the CM ref processor and
923 // empty CM ref processor's discovered lists
924 // (without processing any entries).
925 // * Verify that the STW ref processor is inactive and it's
926 // discovered lists are empty.
927 // * Temporarily set STW ref processor discovery as single threaded.
928 // * Temporarily clear the STW ref processor's _is_alive_non_header
929 // field.
930 // * Finally enable discovery by the STW ref processor.
931 //
932 // The STW ref processor is used to record any discovered
933 // references during the full GC.
934 //
935 // At the end of a full GC we:
936 // * Enqueue any reference objects discovered by the STW ref processor
937 // that have non-live referents. This has the side-effect of
938 // making the STW ref processor inactive by disabling discovery.
939 // * Verify that the CM ref processor is still inactive
940 // and no references have been placed on it's discovered
941 // lists (also checked as a precondition during initial marking).
943 // The (stw) reference processor...
944 ReferenceProcessor* _ref_processor_stw;
946 STWGCTimer* _gc_timer_stw;
947 ConcurrentGCTimer* _gc_timer_cm;
949 G1OldTracer* _gc_tracer_cm;
950 G1NewTracer* _gc_tracer_stw;
952 // During reference object discovery, the _is_alive_non_header
953 // closure (if non-null) is applied to the referent object to
954 // determine whether the referent is live. If so then the
955 // reference object does not need to be 'discovered' and can
956 // be treated as a regular oop. This has the benefit of reducing
957 // the number of 'discovered' reference objects that need to
958 // be processed.
959 //
960 // Instance of the is_alive closure for embedding into the
961 // STW reference processor as the _is_alive_non_header field.
962 // Supplying a value for the _is_alive_non_header field is
963 // optional but doing so prevents unnecessary additions to
964 // the discovered lists during reference discovery.
965 G1STWIsAliveClosure _is_alive_closure_stw;
967 // The (concurrent marking) reference processor...
968 ReferenceProcessor* _ref_processor_cm;
970 // Instance of the concurrent mark is_alive closure for embedding
971 // into the Concurrent Marking reference processor as the
972 // _is_alive_non_header field. Supplying a value for the
973 // _is_alive_non_header field is optional but doing so prevents
974 // unnecessary additions to the discovered lists during reference
975 // discovery.
976 G1CMIsAliveClosure _is_alive_closure_cm;
978 // Cache used by G1CollectedHeap::start_cset_region_for_worker().
979 HeapRegion** _worker_cset_start_region;
981 // Time stamp to validate the regions recorded in the cache
982 // used by G1CollectedHeap::start_cset_region_for_worker().
983 // The heap region entry for a given worker is valid iff
984 // the associated time stamp value matches the current value
985 // of G1CollectedHeap::_gc_time_stamp.
986 unsigned int* _worker_cset_start_region_time_stamp;
988 volatile bool _free_regions_coming;
990 public:
992 void set_refine_cte_cl_concurrency(bool concurrent);
994 RefToScanQueue *task_queue(int i) const;
996 // A set of cards where updates happened during the GC
997 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
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; }
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);
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();
1016 virtual void stop();
1018 // Return the (conservative) maximum heap alignment for any G1 heap
1019 static size_t conservative_max_heap_alignment();
1021 // Initialize weak reference processing.
1022 virtual void ref_processing_init();
1024 // Explicitly import set_par_threads into this scope
1025 using SharedHeap::set_par_threads;
1026 // Set _n_par_threads according to a policy TBD.
1027 void set_par_threads();
1029 virtual CollectedHeap::Name kind() const {
1030 return CollectedHeap::G1CollectedHeap;
1031 }
1033 // The current policy object for the collector.
1034 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
1036 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); }
1038 // Adaptive size policy. No such thing for g1.
1039 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
1041 // The rem set and barrier set.
1042 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
1044 unsigned get_gc_time_stamp() {
1045 return _gc_time_stamp;
1046 }
1048 inline void reset_gc_time_stamp();
1050 void check_gc_time_stamps() PRODUCT_RETURN;
1052 inline void increment_gc_time_stamp();
1054 // Reset the given region's GC timestamp. If it's starts humongous,
1055 // also reset the GC timestamp of its corresponding
1056 // continues humongous regions too.
1057 void reset_gc_time_stamps(HeapRegion* hr);
1059 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
1060 DirtyCardQueue* into_cset_dcq,
1061 bool concurrent, uint worker_i);
1063 // The shared block offset table array.
1064 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
1066 // Reference Processing accessors
1068 // The STW reference processor....
1069 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1071 // The Concurrent Marking reference processor...
1072 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1074 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; }
1075 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; }
1077 virtual size_t capacity() const;
1078 virtual size_t used() const;
1079 // This should be called when we're not holding the heap lock. The
1080 // result might be a bit inaccurate.
1081 size_t used_unlocked() const;
1082 size_t recalculate_used() const;
1084 // These virtual functions do the actual allocation.
1085 // Some heaps may offer a contiguous region for shared non-blocking
1086 // allocation, via inlined code (by exporting the address of the top and
1087 // end fields defining the extent of the contiguous allocation region.)
1088 // But G1CollectedHeap doesn't yet support this.
1090 virtual bool is_maximal_no_gc() const {
1091 return _hrm.available() == 0;
1092 }
1094 // The current number of regions in the heap.
1095 uint num_regions() const { return _hrm.length(); }
1097 // The max number of regions in the heap.
1098 uint max_regions() const { return _hrm.max_length(); }
1100 // The number of regions that are completely free.
1101 uint num_free_regions() const { return _hrm.num_free_regions(); }
1103 // The number of regions that are not completely free.
1104 uint num_used_regions() const { return num_regions() - num_free_regions(); }
1106 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1107 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1108 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
1109 void verify_dirty_young_regions() PRODUCT_RETURN;
1111 #ifndef PRODUCT
1112 // Make sure that the given bitmap has no marked objects in the
1113 // range [from,limit). If it does, print an error message and return
1114 // false. Otherwise, just return true. bitmap_name should be "prev"
1115 // or "next".
1116 bool verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
1117 HeapWord* from, HeapWord* limit);
1119 // Verify that the prev / next bitmap range [tams,end) for the given
1120 // region has no marks. Return true if all is well, false if errors
1121 // are detected.
1122 bool verify_bitmaps(const char* caller, HeapRegion* hr);
1123 #endif // PRODUCT
1125 // If G1VerifyBitmaps is set, verify that the marking bitmaps for
1126 // the given region do not have any spurious marks. If errors are
1127 // detected, print appropriate error messages and crash.
1128 void check_bitmaps(const char* caller, HeapRegion* hr) PRODUCT_RETURN;
1130 // If G1VerifyBitmaps is set, verify that the marking bitmaps do not
1131 // have any spurious marks. If errors are detected, print
1132 // appropriate error messages and crash.
1133 void check_bitmaps(const char* caller) PRODUCT_RETURN;
1135 // Do sanity check on the contents of the in-cset fast test table.
1136 bool check_cset_fast_test() PRODUCT_RETURN_( return true; );
1138 // verify_region_sets() performs verification over the region
1139 // lists. It will be compiled in the product code to be used when
1140 // necessary (i.e., during heap verification).
1141 void verify_region_sets();
1143 // verify_region_sets_optional() is planted in the code for
1144 // list verification in non-product builds (and it can be enabled in
1145 // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1).
1146 #if HEAP_REGION_SET_FORCE_VERIFY
1147 void verify_region_sets_optional() {
1148 verify_region_sets();
1149 }
1150 #else // HEAP_REGION_SET_FORCE_VERIFY
1151 void verify_region_sets_optional() { }
1152 #endif // HEAP_REGION_SET_FORCE_VERIFY
1154 #ifdef ASSERT
1155 bool is_on_master_free_list(HeapRegion* hr) {
1156 return _hrm.is_free(hr);
1157 }
1158 #endif // ASSERT
1160 // Wrapper for the region list operations that can be called from
1161 // methods outside this class.
1163 void secondary_free_list_add(FreeRegionList* list) {
1164 _secondary_free_list.add_ordered(list);
1165 }
1167 void append_secondary_free_list() {
1168 _hrm.insert_list_into_free_list(&_secondary_free_list);
1169 }
1171 void append_secondary_free_list_if_not_empty_with_lock() {
1172 // If the secondary free list looks empty there's no reason to
1173 // take the lock and then try to append it.
1174 if (!_secondary_free_list.is_empty()) {
1175 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1176 append_secondary_free_list();
1177 }
1178 }
1180 inline void old_set_remove(HeapRegion* hr);
1182 size_t non_young_capacity_bytes() {
1183 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes();
1184 }
1186 void set_free_regions_coming();
1187 void reset_free_regions_coming();
1188 bool free_regions_coming() { return _free_regions_coming; }
1189 void wait_while_free_regions_coming();
1191 // Determine whether the given region is one that we are using as an
1192 // old GC alloc region.
1193 bool is_old_gc_alloc_region(HeapRegion* hr) {
1194 return _allocator->is_retained_old_region(hr);
1195 }
1197 // Perform a collection of the heap; intended for use in implementing
1198 // "System.gc". This probably implies as full a collection as the
1199 // "CollectedHeap" supports.
1200 virtual void collect(GCCause::Cause cause);
1202 // The same as above but assume that the caller holds the Heap_lock.
1203 void collect_locked(GCCause::Cause cause);
1205 virtual bool copy_allocation_context_stats(const jint* contexts,
1206 jlong* totals,
1207 jbyte* accuracy,
1208 jint len);
1210 // True iff an evacuation has failed in the most-recent collection.
1211 bool evacuation_failed() { return _evacuation_failed; }
1213 void remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, const HeapRegionSetCount& humongous_regions_removed);
1214 void prepend_to_freelist(FreeRegionList* list);
1215 void decrement_summary_bytes(size_t bytes);
1217 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1218 virtual bool is_in(const void* p) const;
1219 #ifdef ASSERT
1220 // Returns whether p is in one of the available areas of the heap. Slow but
1221 // extensive version.
1222 bool is_in_exact(const void* p) const;
1223 #endif
1225 // Return "TRUE" iff the given object address is within the collection
1226 // set. Slow implementation.
1227 inline bool obj_in_cs(oop obj);
1229 inline bool is_in_cset(oop obj);
1231 inline bool is_in_cset_or_humongous(const oop obj);
1233 private:
1234 // This array is used for a quick test on whether a reference points into
1235 // the collection set or not. Each of the array's elements denotes whether the
1236 // corresponding region is in the collection set or not.
1237 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test;
1239 public:
1241 inline InCSetState in_cset_state(const oop obj);
1243 // Return "TRUE" iff the given object address is in the reserved
1244 // region of g1.
1245 bool is_in_g1_reserved(const void* p) const {
1246 return _hrm.reserved().contains(p);
1247 }
1249 // Returns a MemRegion that corresponds to the space that has been
1250 // reserved for the heap
1251 MemRegion g1_reserved() const {
1252 return _hrm.reserved();
1253 }
1255 virtual bool is_in_closed_subset(const void* p) const;
1257 G1SATBCardTableLoggingModRefBS* g1_barrier_set() {
1258 return (G1SATBCardTableLoggingModRefBS*) barrier_set();
1259 }
1261 // This resets the card table to all zeros. It is used after
1262 // a collection pause which used the card table to claim cards.
1263 void cleanUpCardTable();
1265 // Iteration functions.
1267 // Iterate over all the ref-containing fields of all objects, calling
1268 // "cl.do_oop" on each.
1269 virtual void oop_iterate(ExtendedOopClosure* cl);
1271 // Iterate over all objects, calling "cl.do_object" on each.
1272 virtual void object_iterate(ObjectClosure* cl);
1274 virtual void safe_object_iterate(ObjectClosure* cl) {
1275 object_iterate(cl);
1276 }
1278 // Iterate over all spaces in use in the heap, in ascending address order.
1279 virtual void space_iterate(SpaceClosure* cl);
1281 // Iterate over heap regions, in address order, terminating the
1282 // iteration early if the "doHeapRegion" method returns "true".
1283 void heap_region_iterate(HeapRegionClosure* blk) const;
1285 // Return the region with the given index. It assumes the index is valid.
1286 inline HeapRegion* region_at(uint index) const;
1288 // Calculate the region index of the given address. Given address must be
1289 // within the heap.
1290 inline uint addr_to_region(HeapWord* addr) const;
1292 inline HeapWord* bottom_addr_for_region(uint index) const;
1294 // Divide the heap region sequence into "chunks" of some size (the number
1295 // of regions divided by the number of parallel threads times some
1296 // overpartition factor, currently 4). Assumes that this will be called
1297 // in parallel by ParallelGCThreads worker threads with discinct worker
1298 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
1299 // calls will use the same "claim_value", and that that claim value is
1300 // different from the claim_value of any heap region before the start of
1301 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by
1302 // attempting to claim the first region in each chunk, and, if
1303 // successful, applying the closure to each region in the chunk (and
1304 // setting the claim value of the second and subsequent regions of the
1305 // chunk.) For now requires that "doHeapRegion" always returns "false",
1306 // i.e., that a closure never attempt to abort a traversal.
1307 void heap_region_par_iterate_chunked(HeapRegionClosure* cl,
1308 uint worker_id,
1309 uint num_workers,
1310 jint claim_value) const;
1312 // It resets all the region claim values to the default.
1313 void reset_heap_region_claim_values();
1315 // Resets the claim values of regions in the current
1316 // collection set to the default.
1317 void reset_cset_heap_region_claim_values();
1319 #ifdef ASSERT
1320 bool check_heap_region_claim_values(jint claim_value);
1322 // Same as the routine above but only checks regions in the
1323 // current collection set.
1324 bool check_cset_heap_region_claim_values(jint claim_value);
1325 #endif // ASSERT
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();
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);
1335 // Iterate over the regions (if any) in the current collection set.
1336 void collection_set_iterate(HeapRegionClosure* blk);
1338 // As above but starting from region r
1339 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1341 HeapRegion* next_compaction_region(const HeapRegion* from) const;
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;
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;
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;
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.
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;
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;
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;
1380 // Does this heap support heap inspection? (+PrintClassHistogram)
1381 virtual bool supports_heap_inspection() const { return true; }
1383 // Section on thread-local allocation buffers (TLABs)
1384 // See CollectedHeap for semantics.
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;
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 }
1409 virtual bool card_mark_must_follow_store() const {
1410 return true;
1411 }
1413 inline bool is_in_young(const oop obj);
1415 #ifdef ASSERT
1416 virtual bool is_in_partial_collection(const void* p);
1417 #endif
1419 virtual bool is_scavengable(const void* addr);
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);
1428 // Returns "true" iff the given word_size is "very large".
1429 static bool isHumongous(size_t word_size) {
1430 // Note this has to be strictly greater-than as the TLABs
1431 // are capped at the humongous thresold 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 }
1438 // Update mod union table with the set of dirty cards.
1439 void updateModUnion();
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);
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 }
1457 // Print the maximum heap capacity.
1458 virtual size_t max_capacity() const;
1460 virtual jlong millis_since_last_gc();
1463 // Convenience function to be used in situations where the heap type can be
1464 // asserted to be this type.
1465 static G1CollectedHeap* heap();
1467 void set_region_short_lived_locked(HeapRegion* hr);
1468 // add appropriate methods for any other surv rate groups
1470 YoungList* young_list() const { return _young_list; }
1472 // debugging
1473 bool check_young_list_well_formed() {
1474 return _young_list->check_list_well_formed();
1475 }
1477 bool check_young_list_empty(bool check_heap,
1478 bool check_sample = true);
1480 // *** Stuff related to concurrent marking. It's not clear to me that so
1481 // many of these need to be public.
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();
1490 bool isMarkedPrev(oop obj) const;
1491 bool isMarkedNext(oop obj) const;
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 }
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 }
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.
1516 // Added if it is NULL it isn't dead.
1518 inline bool is_obj_dead(const oop obj) const;
1520 inline bool is_obj_ill(const oop obj) const;
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);
1527 ConcurrentMark* concurrent_mark() const { return _cm; }
1529 // Refinement
1531 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
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();
1543 // Optimized nmethod scanning support routines
1545 // Register the given nmethod with the G1 heap
1546 virtual void register_nmethod(nmethod* nm);
1548 // Unregister the given nmethod from the G1 heap
1549 virtual void unregister_nmethod(nmethod* nm);
1551 // Free up superfluous code root memory.
1552 void purge_code_root_memory();
1554 // Rebuild the stong code root lists for each region
1555 // after a full GC
1556 void rebuild_strong_code_roots();
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);
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);
1565 // Redirty logged cards in the refinement queue.
1566 void redirty_logged_cards();
1567 // Verification
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;}
1577 // Perform any cleanup actions necessary before allowing a verification.
1578 virtual void prepare_for_verify();
1580 // Perform verification.
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);
1597 // Override; it uses the "prev" marking information
1598 virtual void verify(bool silent);
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.
1605 bool is_obj_dead_cond(const oop obj,
1606 const HeapRegion* hr,
1607 const VerifyOption vo) const;
1609 bool is_obj_dead_cond(const oop obj,
1610 const VerifyOption vo) const;
1612 // Printing
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;
1618 virtual void print_gc_threads_on(outputStream* st) const;
1619 virtual void gc_threads_do(ThreadClosure* tc) const;
1621 // Override
1622 void print_tracing_info() const;
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;
1628 public:
1629 size_t pending_card_num();
1630 size_t cards_scanned();
1632 protected:
1633 size_t _max_heap_capacity;
1634 };
1636 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP